Injection-molded light guide member and head-mounted display

Abstract

The present invention aims to provide an injection-molded light guide member that can provide high-resolution images without distortion, while suppressing defects such as brightness unevenness, color unevenness, and rainbow appearance, even when partial mirrors with polarization-selective reflectivity characteristics are configured in the input coupler, waveguide section, and output coupler. [Solution] The light guide comprises a base material, an input coupler for injecting light from an image display device into the light guide member, two opposing light guide sections that guide the incident light through multiple repeated reflections, and an output coupler for extracting the guided light from the light guide towards the observer's eye through one of the functions of bending, diffraction, or reflection, with an absolute value of the photoelastic coefficient of 10 × 10 -12 Pa -1 The following describes an injection-molded light guide member, in which at least one of the three surfaces (two waveguide surfaces and the output coupler surface) has a partial mirror that transmits a portion of the light and reflects the remaining portion.

Description

[Technical Field]

[0001] The present invention relates to an injection-molded light guide member and a head-mounted display. [Background technology]

[0002] In recent years, there has been a surge in the development of devices for virtual reality (VR), augmented reality (AR), and extended reality (XR), which encompasses both.

[0003] While the boundaries between these frameworks are becoming increasingly blurred, devices that allow the viewer to see through the real world via a lens in front of their eyes (eyepoint) are generally classified as AR head-mounted displays. Figure 1 illustrates the basic configuration of an AR head-mounted display, specifically its optical system. Referring to Figure 1, the basic configuration of an AR head-mounted display is as follows: After image light is generated by an image display device 12, this image light is introduced into the transparent light guide member 11 using a prism, mirror, diffraction grating, or holographic element as an input coupler installed in the light incident section 111 of the transparent light guide member 11. After the waveguide section (outside-side waveguide section 113 and eye-side waveguide section 112) inside the light guide member 11 is guided by total internal reflection, the image light is output towards the user's eye by an output coupler 114, which is a mirror, diffraction grating, or holographic element positioned in a way that disrupts total internal reflection, and the light is extracted from the light extraction section 115. As a result, the real world (external light 14) can be observed as see-through through the transparent waveguide to the observer's pupil 13, while the image light is superimposed on the real world and observed by the observer's pupil 13 through the optical system. Such devices are disclosed in Patent Documents 1 and 2.

[0004] These devices require a comfortable fit for the observer and a display that is natural and unobtrusive when viewing images. To achieve large-screen displays of diverse information while miniaturizing, reducing the overall weight, size, and thickness of the device, an optical system with a wide field of view is required. Furthermore, an optical system characterized by guiding image light within a thin-walled light guide element is an essential technology for realizing thin and lightweight devices, and its advanced implementation is expected to enable its use as a post-smartphone device.

[0005] As an example of such an optical system, Patent Document 1 shows an example in which image light is collimated and incident into a waveguide, and diffraction by a volume hologram formed as an input coupler, which is recorded as interference fringes with a sloped refractive index distribution, is used to guide the waveguide by total internal reflection, and the light is diffracted by a volume hologram formed as an output coupler on the eye side and extracted on the observer's eye side. Patent Document 2 also shows a configuration in which multiple wire grid mirrors are arranged in the output coupler with their reflection axes alternately perpendicular. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication No. 2018 / 012108 [Patent Document 2] Japanese Patent Publication No. 2019-101370 [Patent Document 3] Japanese Patent Publication No. 2021-162621 [Patent Document 4] International Publication No. 2021 / 182598 [Patent Document 5] Japanese Patent Publication No. 2023-059010 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, in such optical systems, if the prisms, mirrors, diffraction gratings, and holographic elements used in the input and output couplers have polarization selectivity, there is a concern that the polarization of the image light may be distorted or localized as the image light is guided through the optical guide material, adversely affecting the image light extracted by the output coupler. When using glass optical guide materials, the effect of polarization selectivity is small, and the image light can be extracted as designed. However, high refractive index and high flatness glass for waveguides is extremely expensive, which is a factor hindering the widespread adoption of AR headsets aimed at the post-smartphone era. Therefore, the use of resin waveguides and resin optical guide materials is required, but the effect of polarization selectivity has not been sufficiently investigated.

[0008] Furthermore, when using resin light guide members, if the goal is to guide the image light to the waveguide using total internal reflection, as in the configuration disclosed in Patent Document 3, there is no choice of material with a high refractive index like glass in the resin composition, and the refractive index of the substrate is low, resulting in a problem where the critical angle becomes large. In addition, in order to maintain total internal reflection, it is necessary to guide the light at an incident angle greater than the critical angle, which means that it is not possible to guide the image at a fine pitch, making it impossible to design a fine eye box, and furthermore, the field of view (angle of view of the virtual image), which is related to the size of the virtual image, cannot be wide.

[0009] Furthermore, when using resin-based light guide members, there was a problem in obtaining molded pieces with high flatness (parallelism). Conventional techniques have included the production of cast plates obtained by pouring methyl methacrylate (MMA) monomer into synthetic quartz cells with high mirror-like surface properties and a thickness tolerance of 1 μm and curing them by radical polymerization, and the production of transparent plates with high flatness by chemical mechanical polishing of these cast plates (Patent Documents 3 and 4). However, due to the durability of the molds and the length of the processing process, mass production is difficult. Also, when considered as eyeglass lenses, it is not possible to give them a curved surface for vision correction, and it is difficult to give them a shape for fixing to the housing, so there has been a strong demand for light guide members that can be obtained by injection molding. Furthermore, while Patent Document 4 describes the fabrication of a light guide plate with a diffraction grating by injection molding and specifies desirable flatness and parallelism, the examples provided do not include evaluation results for these characteristics, merely indicating an ideal public range. Therefore, it basically assumes polishing to achieve high surface accuracy, and sufficient consideration has not been given to techniques that can be implemented even when the light guide plate is curved, for example.

[0010] The present invention has been made in view of the above circumstances, and aims to provide an injection-molded light guide member and a head-mounted display equipped with the light guide member that can provide an image without distortion due to surface deformation, while suppressing defects such as brightness unevenness, color unevenness and rainbow appearance, even if the light guide member has a partial mirror having polarization-selective reflectivity characteristics on at least one surface of the input coupler, waveguide section and output coupler. [Means for solving the problem]

[0011] This invention was made as a result of the inventors' diligent consideration in light of the above-mentioned problems. The inventors have found that a light guide member formed from a thermoplastic resin composition with sufficiently high heat resistance, a low photoelastic coefficient, and a ring structure in the main chain or side chain, exhibiting low anisotropy of residual stress during molding and excellent surface accuracy, can suppress birefringence after molding and provide a clear image with minimal changes in surface accuracy and dimensions due to environmental changes. Furthermore, they have found that by utilizing a partial mirror that transmits a portion of the light and reflects the remaining portion, it is possible to obtain a light guide member that solves the critical angle problem mentioned above while also providing new functions.

[0012] In other words, the present invention is as follows. [1] An injection-molded light guide member for use in an image display device having an eyepiece optical system that guides light from an image display element toward the observer's eyeball, The base material and, An input coupler for directing light from the image display device into the light guide body, Two opposing waveguide sections guide the incident light through multiple repeated reflections, It comprises an output coupler for extracting light from a light guide member towards the observer's eye by bending, diffraction, or reflection, The absolute value of the photoelastic coefficient is 10 × 10 -12 Pa -1 The following: Of the three surfaces in total—the two waveguide surfaces and the output coupler surface—at least one surface has a partial mirror formed on it that transmits a portion of the light and reflects the other portion. The partial mirror has a reflectivity difference of 10% or more and less than 40% between a first polarization that becomes S-polarized and a second polarization that is orthogonal to the first polarization when reflected by the partial mirror at an incident angle of 30°, and P-polarized. The waveguide portion has an in-plane phase difference of 20 nm or less within its effective area. The aforementioned base portion is made of a thermoplastic resin composition having a ring structure in the main chain or side chain, and is characterized by having a glass transition temperature (Tg) of 115 to 150°C, wherein the injection-molded light guide member is characterized by this composition.

[0013] [2] The shortest distance between the two waveguide sections is 0.6 mm or more and 25 mm or less. The projection length of the light guide member in the wave guiding direction is 10 mm or more and 50 mm or less. The injection-molded light guide member according to [1], characterized in that the two wave-guiding portions on the two surfaces each have a PV value of 10.0 μm or less in the effective area where light is guided.

[0014] [3] One of the two waveguide sections is the external waveguide section, The injection-molded light guide member according to [1] or [2], characterized in that the external-side wave guide portion is formed with the partial mirror which transmits a portion of the light and reflects the remaining portion.

[0015] [4] An injection-molded light guide member according to any one of [1] to [3], characterized in that when a first polarization of 500 to 600 nm with a wavelength that becomes S-polarized upon reflection in the waveguide is incident from the light incident part, the light is guided in the waveguide part, and then the light is taken out from the light extraction part via the output coupler, the ratio (Tp / Tc) of the amount of light taken out via a polarizer arranged so that the axis of the first polarization coincides with the transmission axis and the amount of light taken out via a polarizer arranged so that the axis of the first polarization coincides with the transmission axis is 5 or more when the ratio (Rs / Rp) of the part of the partial mirror with the largest ratio of S-polarized reflectance to P-polarized reflectance (Rs / Rp) is divided by the ratio (Rs / Rp) of the surface with the largest ratio of S-polarized reflectance to P-polarized reflectance (Rs / Rp).

[0016] [5] The injection-molded light guide member according to [4], characterized in that the value obtained by dividing the ratio (Tp / Tc) by the ratio (Rs / Rp) of the surface with the largest ratio (Rs / Rp) is 10 or more.

[0017] [6] The injection-molded light guide member according to any one of [1] to [5], characterized in that the output coupler has a partial mirror formed therein that transmits a portion of the light and reflects the remaining portion.

[0018] [7] The injection-molded light guide member according to any one of [1] to [6], characterized in that the thermoplastic resin composition contains 0.5 to 2.8% by mass of a higher fatty acid ester.

[0019] [8] The injection-molded light guide member according to any one of [1] to [7], characterized in that the thermoplastic resin composition is a methacrylic resin composition.

[0020] A head-mounted display characterized by comprising an injection-molded light guide member as described in any one of [9] [1] to [8].

[0021]

[10] [9] A head-mounted display as described above, A head-mounted display characterized in that, in at least one of the optical output section and the eye-side waveguide section, the reflectance of S-polarized light at an incident angle of 5° is greater than the reflectance of P-polarized light, and the difference between the reflectance of S-polarized light and P-polarized light is 5% or more.

[0022]

[11] [9] or

[10] a head-mounted display, Partial mirrors are formed on both sides of the two waveguide sections, either partially or entirely, which transmit a portion of the light and reflect the remaining portion. A head-mounted display characterized by guiding light at an incident angle smaller than the critical angle of the substrate portion.

[0023]

[12] A head-mounted display as described in any one of [9] to

[11] , A head-mounted display characterized by having a linear polarizing plate on a straight line extending outwards from the observer's eyeball to the output coupler of the light guide member.

[0024]

[13] A head-mounted display as described in any one of [9] to

[12] , A head-mounted display characterized by having a linear polarizer and a half-wave plate or a phase difference layer that imparts a phase difference of half a wavelength, in order from the outside side, on a straight line extending to the outside world, connecting the observer's eyeball and the output coupler of the light guide member. [Effects of the Invention]

[0025] According to the present invention, even when partial mirrors having polarization-selective reflectivity characteristics are configured in the input coupler, waveguide section, and output coupler, it is possible to provide an injection-molded light guide member and a head-mounted display equipped therewith that can provide images while suppressing defects such as brightness unevenness, color unevenness, and rainbow appearance. [Brief explanation of the drawing]

[0026] [Figure 1]Figure 1 is a conceptual diagram of the optical system used to explain the basic configuration of an AR head-mounted display. [Figure 2A] Figure 2A is a conceptual diagram of an optical system that simulates an AR head-mounted display equipped with a light guide member according to one embodiment of the present invention. [Figure 2B] Figure 2B is a conceptual diagram of an optical system simulating an AR head-mounted display equipped with a light guide member according to one embodiment of the present invention. [Figure 2C] Figure 2C is a conceptual diagram of an optical system simulating an AR head-mounted display equipped with a light guide member according to one embodiment of the present invention. [Figure 3] Figure 3 is a conceptual diagram illustrating the measurement of polarization retention characteristics in an optical system with multiple eye points. [Figure 4] Figure 4 illustrates the vibration axes of S-polarized and P-polarized light during reflection within the light guide member. [Figure 5] Figure 5 illustrates the vibration axes of S-polarized and P-polarized light during reflection from surfaces such as the ground and water. [Figure 6] Figure 6 is a conceptual diagram illustrating a configuration in which a linear polarizer is provided to block the polarization of strongly reflected ambient light. [Figure 7] Figure 7 is a conceptual diagram illustrating a configuration that enhances the utilization efficiency of light guided within a light guide member while incorporating a linear polarizer and a phase difference plate to shield the polarization of strongly reflected ambient light. [Figure 8] Figure 8 is a conceptual diagram showing the measurement of PV values ​​on the substrate surfaces of the light incident section, waveguide section, input coupler, and output coupler. [Figure 9] Figure 9 shows an example of the polarization reflectance characteristics of the partial mirror in this embodiment. [Figure 10A] Figure 10A is a conceptual diagram showing the schematic of the experimental setup used to evaluate the polarization retention characteristics when the waveguide is incident at an incident angle of 45°. [Figure 10B] Figure 10B is a conceptual diagram showing the schematic of the experimental setup used to evaluate the polarization retention characteristics when the waveguide is incident at an incident angle of 40°. [Figure 11]Figure 11 is a conceptual diagram of image evaluation using the light guide member of this embodiment, set and combined with an AR head. [Figure 12] Figure 12 is a conceptual diagram of a molded product holding method implemented in Example 2 as an example of a method for holding a molded product in the air after molding. [Figure 13] Figure 13 is a conceptual diagram of the AR headset shown in Example 16, which is one embodiment of this model. [Modes for carrying out the invention]

[0027] The following describes in detail an embodiment for carrying out the present invention (hereinafter referred to as "this embodiment"), but the present invention is not limited to the following description and can be implemented in various modifications within the scope of its gist. In descriptions of the polarization state and phase difference of light, concepts such as linear polarization, circular polarization, elliptic polarization, and phase differences of 1 / 4λ (1 / 4 wavelength) and 1 / 2λ (1 / 2 wavelength) generally represent a broad range of states. Therefore, errors in these states do not hinder the essential effects of the present invention. Furthermore, the phase difference generated in each optical element is the phase difference with respect to light of wavelength λ, and the wavelength λ can be selected from any wavelength in the visible light range, for example, λ = 587.6 nm, but is not limited to this.

[0028] [Explanation of terms] In this specification, "hydrocarbon group" refers to a monovalent group and includes linear, branched, or cyclic saturated hydrocarbon groups, unsaturated hydrocarbon groups, or aromatic groups. For example, "hydrocarbon group" is one group selected from the group consisting of alkyl groups (e.g., the alkyl groups above), alkenyl groups (e.g., the alkenyl groups above), aryl groups (e.g., the aryl groups above), aryloxy groups (e.g., the aryloxy groups above), aralkyl groups (e.g., the aralkyl groups above), and alkoxy groups (e.g., the alkoxy groups above).

[0029] In this specification, "aliphatic hydrocarbon group" refers to a group from which one or more hydrogen atoms bonded to an aliphatic carbon of an aliphatic compound have been removed. More specifically, a monovalent aliphatic hydrocarbon group refers to a group from which one hydrogen atom bonded to an aliphatic carbon of an aliphatic compound has been removed, and a divalent aliphatic hydrocarbon group refers to a group from which two hydrogen atoms bonded to an aliphatic carbon of an aliphatic compound have been removed. Furthermore, in this specification, "aliphatic hydrocarbon group" refers to a group whose main chain is an aliphatic hydrocarbon, and which may have an aromatic ring or the like in part. Examples of divalent aliphatic hydrocarbon groups include optionally substituted alkylene groups, optionally substituted cycloalkylene groups, optionally substituted alkenylene groups, optionally substituted cycloalkenylene groups, and optionally substituted alkapolienylene groups (preferably 2 to 10, more preferably 2 to 6, even more preferably 2 to 4, and even more preferably 2 double bonds).

[0030] In this specification, "aromatic hydrocarbon group" refers to a group obtained by removing one hydrogen atom from the aromatic ring of an aromatic hydrocarbon compound. Specific examples include the phenyl group, biphenyl group, tolyl group, indenyl group, naphthyl group, anthryl group, fluorenyl group, pyrenyl group, phenanthnyl group, and mestyl group.

[0031] Examples of arylalkyl groups used herein include benzyl groups, phenylethyl groups, phenylpropyl groups, naphthylmethyl groups, naphthylethyl groups, and naphthylpropyl groups.

[0032] In this specification, examples of aryl groups include phenyl, tolyl, xylyl, naphthyl, biphenyl, anthracenyl, and phenanthryl groups.

[0033] In this specification, alkyl groups may be linear or branched, and examples include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, isobutyl group, tert-butyl group, 2-methylbutyl group, n-pentyl group, 2-pentyl group, 3-pentyl group, 2,2-dimethylpropyl group, n-hexyl group, heptyl group, n-octyl group, 1,1,3,3-tetramethylbutyl group, 2-ethylhexyl group, nonyl group, decyl group, undecyl group, dodecyl group, and the like.

[0034] In this specification, examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

[0035] In this specification, examples of alkoxy groups include methoxy groups, ethoxy groups, n-butoxy groups, and methoxyethoxy groups.

[0036] Examples of cycloalkyl groups used herein include cyclopropyl group, cyclopropylmethyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cyclohexylmethyl group, trimethylcyclohexyl group, thuzyl group, norbornyl group, bornyl group, norcalyl group, calyl group, menthyl group, norpinyl group, pinyl group, 1-adamantyl group, and 2-adamantyl group.

[0037] [Injection-molded light guide component] The injection-molded light guide member of this embodiment is An injection-molded light guide member (hereinafter sometimes simply referred to as "light guide member") used in an image display device having an eyepiece optical system that guides light from an image display element toward the observer's eyeball, The base material and, An input coupler for directing light from an image display device into a light guide, Two opposing light guide sections guide the incident light through multiple repeated reflections, It comprises an output coupler for extracting light from a light guide towards the observer's eye by bending, diffraction, or reflection, The absolute value of the photoelastic coefficient is 10 × 10 -12 Pa -1 The following: Of the three surfaces in total—the two waveguide surfaces and the output coupler surface—at least one surface has a partial mirror formed on it that transmits a portion of the light and reflects the other portion. The partial mirror has a reflectivity difference of 10% or more and less than 40% between a first polarization that becomes S-polarized and a second polarization that is orthogonal to the first polarization when reflected by the partial mirror at an incident angle of 30°, and P-polarized. The waveguide portion has an in-plane phase difference of 20 nm or less within its effective area. The base material is composed of a thermoplastic resin composition having a ring structure in the main chain or side chain, and is characterized by having a glass transition temperature (Tg) of 115 to 150°C. According to the above injection-molded light guide member, even when partial mirrors with polarization-selective reflectivity characteristics are configured in the input coupler, waveguide section, and output coupler, it is possible to provide images while suppressing defects such as brightness unevenness, color unevenness, and rainbow appearance.

[0038] The inventors have discovered that by forming a light guide member from a thermoplastic resin composition with sufficiently high heat resistance, a low photoelastic coefficient, and a ring structure in the main chain or side chain, and having low residual stress anisotropy, it is possible to obtain a light guide member that can suppress birefringence after molding and provide a clear image with little change in surface accuracy and dimensions due to environmental changes. Furthermore, they have discovered that by using a partial mirror that transmits a portion of the light and reflects the remaining portion, it is possible to obtain a light guide member that can solve the critical angle problem mentioned above while also providing new functions.

[0039] Specifically, by using a partial mirror that transmits some of the light and reflects the other half (for example, one designed with a reflectivity of 30% and transmittance of 70%), it becomes possible to force the light to be guided by reflection within the substrate of the light guide member, regardless of the critical angle. Furthermore, if the incident angle is designed to be sufficiently large, we have found a light guide member that can guide the image light without loss by total internal reflection. In conventional technology, partial mirrors were not actively used in the waveguide section. However, the inventor noticed that another characteristic of partial mirrors is that their reflectivity exhibits polarization dependence depending on the mirror's configuration, and furthermore, that their characteristics change depending on the angle of incidence. For example, if a partial mirror is used in which the difference in reflectivity between the first polarization and the second polarization orthogonal to the first polarization at an incidence angle of 30° is 10% or more, even if the design reflectivity is 30% for unpolarized light, if a partial mirror with, for example, an S-polarization reflectivity of 50% and a P-polarization reflectivity of 10% is used, and the input image light is incident with S-polarization, it becomes possible to improve the efficiency of image light utilization by a proportion corresponding to the number of reflections in the waveguide section. However, the inventors have discovered that when such a waveguide and output coupler have polarization-selective reflectivity (or transmittance) characteristics, the polarization of the guided image light is disturbed by the birefringence of the resin substrate, causing uneven brightness, rainbows, and color variations in the image. By using a light guide member made of the low birefringence resin composition of the present invention, it is possible to provide a light guide member that does not cause uneven brightness, triple rainbows, color variations, etc. in the image.

[0040] The injection-molded light guide member of this embodiment (hereinafter sometimes simply referred to as "light guide member") may also include other members (for example, polarizers, waveplates, phase difference coatings, metal mirror coatings, anti-reflective coatings, hard coatings, and other functional coating layers) as long as the effects of the present invention are not impaired. The above-mentioned other members may be one or multiple.

[0041] -composition- The shape of the light guide member is not particularly limited, but it must include an input coupler for inducing light into the light guide, a waveguide section for guiding light through repeated reflection, and an output coupler for extracting light. The light guide member also includes a light incidence section into which light is incident and a light extraction section for extracting the guided light to the outside. The emission section may have the same configuration as the output coupler. The input and output couplers are not particularly limited, but they can be diffraction gratings made of gratings, volume holograms, diffraction gratings made of liquid crystals, as well as mirrors made of thin metal films or partial mirrors made of dielectric multilayer films. When the input coupler is constructed using a reflective surface, it is preferable to use a mirror with high reflectivity that does not cause light loss. Furthermore, when the input coupler is constructed using a diffracting surface, it is preferable to use a diffracting element that does not cause light loss and has high diffraction efficiency. When the input coupler is configured as a transparent surface, it is preferable to apply an anti-reflective coating that suppresses reflectivity.

[0042] Furthermore, the input coupler and output coupler do not need to be parallel to the two surfaces that constitute the waveguide section; they may be formed as inclined surfaces that constitute the prism section for bending the image light by reflection.

[0043] The waveguide section is preferably configured to utilize total internal reflection. However, if the critical angle is limited due to the need to expand the field of view of the image or the design of the eyebox, it is preferable to use a partial mirror. However, when using a partial mirror, the amount of light is attenuated by repeated reflection. Therefore, it is preferable to set the reflectivity of the image light to a high level by adjusting the reflectivity of the partial mirror and utilizing the polarization reflectivity characteristics, taking into account the brightness of the image light visible to the observer. Even when using a partial mirror, it is preferable to satisfy the total internal reflection conditions, as this allows for waveguide without light loss.

[0044] Furthermore, the waveguide section has two surfaces in the light guide member. One surface is referred to as the external-side waveguide section, and the other surface is referred to as the eye-side waveguide section. The eye-side waveguide section is the waveguide section closest to the observer's eyeball, while the other waveguide section is the external-side waveguide section.

[0045] Here, with reference to Figures 2A to 2C, an example of the configuration of the light guide member in this embodiment will be described. Light from the image display element is introduced into the light guide member using an input coupler installed at the light incidence part of the light guide member. In Figure 2A, a prism; in Figure 2B, a diffraction grating, a holographic element (hologram), and a liquid crystal diffraction element; and in Figure 2C, a mirror, a partial mirror, and a polarizing beam splitter (reflective polarizing element). After the light is guided through the waveguide section (outside-side waveguide section and eye-side waveguide section) within the light guide member by total internal reflection, the image light is output towards the user's pupil by an output coupler (mirror, diffraction grating, or holographic element) positioned to disrupt the total internal reflection, and the light that has passed through the light guide member is observed by the observer's pupil. In Figures 2A to 2C, a linear polarizing element is placed between the image display element and the light guide member. A collimating optical system (not shown) may also be placed separately between the image display element and the light guide member. Additionally, a correction prism is attached to the output coupler.

[0046] The surface of the light guide member according to this embodiment may be further subjected to surface functionalization treatments such as hard coating, anti-reflective coating, metal mirror coating, phase difference layer application, transparent conductive coating, electromagnetic wave shielding coating, or gas barrier coating, to the extent that the effects of the present invention are not impaired. The thickness of these functional layers is not particularly limited, but is usually in the range of 0.01 to 10 μm. If reflection at the interface due to the refractive index difference between the substrate and the functional layer is undesirable, it is desirable to keep the refractive index difference between the substrate and the functional layer within ±0.05. Alternatively, by making the layer thin, it is possible to reduce the appearance of double images due to reflection at the interface between the substrate and the functional layer and reflection at the interface between the functional layer and the air.

[0047] The hard coat layer to be applied to the surface of the light guide member is formed by applying a coating solution, obtained by dissolving or dispersing an acrylate such as a silicone-based curable resin, an organic polymer composite inorganic fine particle-containing curable resin, urethane acrylate, epoxy acrylate, or polyfunctional acrylate, along with a photopolymerization initiator or thermal polymerization initiator, in an organic solvent using a conventionally known coating method, then drying and curing it with light or heat. Before applying the hard coat layer, a method can be used in which, for example, an easy-adhesion layer, primer layer, or anchor layer containing inorganic fine particles is provided in advance to improve adhesion, and then the hard coat layer is formed.

[0048] The anti-glare layer applied to the surface of the light guide member is formed by infusing fine particles of silica, melamine resin, acrylic resin, etc., into an ink, applying it onto other functional layers using a conventionally known coating method, and then curing it with heat or light.

[0049] Examples of anti-reflective layers applied to the surface of a light guide member (which may include functional layers such as a hard coat layer) include those consisting of thin films of inorganic materials such as metal oxides, fluorides, silicides, borides, nitrides, and sulfides, and those made by laminating single or multilayer resins with different refractive indices, such as acrylic resins and fluororesins. Furthermore, a thin layer containing composite fine particles of inorganic and organic compounds can also be used.

[0050] A mirror, half-mirror, or partial mirror (a partial mirror with a reflectance-to-transmittance ratio other than 50:50, for example, a transmittance of 15% and a reflectance of 85%, is also acceptable. Furthermore, a mirror is defined as having a reflectance higher than the surface reflectance of the substrate itself) can be applied to the surface of the light guide member (which may include a functional layer such as a hard coat layer). Any suitable material can be used, but for example, it can be constructed by coating a thin layer of metal (for example, silver or aluminum) onto the light guide member. When coating a thin layer of metal, light absorption by the metal occurs, so it is preferable to form a mirror by depositing a thin film dielectric coating on the surface of the light guide member. Alternatively, a combination of the metal coating method and the dielectric coating method may be used. In addition, an SiO2 film, SiO film, or MgF film may be added to the surface of the mirror as a protective film, to the extent that it does not impair its function. The reflectivity and transmittance of light can be controlled by the thickness and number of coating layers, and in dielectric deposition methods, it is possible to design a material that reflects only light of a specific wavelength.

[0051] -size- The size of the injection-molded light guide member in this embodiment is not particularly limited, but it is preferably the same size as that of corrective eyeglasses. Referring to the exemplified light guide members in Figures 2A to 2C, for example, the length of the injection-molded light guide member in the x-axis direction is preferably 10 mm to 80 mm, more preferably 20 mm to 60 mm, and even more preferably 35 mm to 55 mm. If the length in the x-direction is short, there is a risk that the image display element of the eyewear will come into contact with the face. At this distance, by using the light guide member of the present invention, it is possible to guide waves while maintaining the polarization state, suppress the influence of the partial mirror of the present invention which has a reflectance difference of 10% or more between P-polarized and S-polarized light, and present a clear image to the observer. Furthermore, the length of the injection-molded light guide member in the y-axis direction is preferably 10 mm or more and 80 mm or less, more preferably 10 mm or more and 50 mm or less, and even more preferably 25 mm or more and 45 mm or less.

[0052] When using the light guide member of this embodiment in an AR headset, a corrective prism may be provided on the opposite side to allow for a see-through, distortion-free view of the outside world when viewing it through the output coupler. In this case, it is desirable that the difference between the refractive index of the light guide member and the refractive index of the adhesive used to bond the corrective prism to the light guide member be kept within ±0.05. In this case, distortion caused by the difference in refractive index at the joint between the light guide member and the corrective prism can be sufficiently suppressed. Furthermore, optical elements such as a linear polarizer, a linear polarizer and a 1 / 2 wavelength phase difference plate, and a phase difference layer that imparts a 1 / 2 wavelength phase difference may be further installed on the outside side of the corrective prism.

[0053] (Wave guide section) The injection-molded light guide member of this embodiment comprises two opposing waveguide surfaces that guide light from an image display element through multiple repeated reflections. The two waveguide surfaces may be an eye-side waveguide surface on the observer's eye side, and an external-side waveguide surface facing the external environment.

[0054] The shortest distance between the external-side waveguide and the eye-side waveguide, i.e., the shortest distance between the two waveguide surfaces, is preferably 0.6 mm to 25 mm, more preferably 1 mm to 20 mm, and even more preferably 1.2 mm to 20 mm. In other preferred embodiments, the shortest distance between the two waveguide surfaces is preferably 1 mm to 8 mm. A thickness of 8 mm or less is preferred from the viewpoint of weight reduction, as it is difficult to maintain the strength of the light guide member with a thickness of less than 0.6 mm. Furthermore, the thinner the wall, the more warping occurs due to molding distortion and thermal deformation in the case of a resin light guide member, making it difficult to reproduce a flat or accurately curved surface. For this reason, the shortest distance between the two waveguide surfaces is more preferably 1.2 mm to 15 mm, even more preferably 1.5 mm to 7 mm, and particularly preferably 2 mm to 6 mm.

[0055] In the injection-molded light guide member of this embodiment, the waveguide portion can be a flat or curved surface. When the waveguide portion is curved, in order to avoid a change in the incident angle during waveguide operation, it is preferable to design the waveguide portion to have a radius of curvature of R+tmm, which is the radius of curvature Rmm on the eye side, with the radius of curvature being increased by the thickness t, when the distance between the waveguide portions of the two surfaces of the light guide member is the thickness t.

[0056] The waveguide portion preferably has a projected length of 10 mm or more in the direction of guidance. The direction of guidance refers to the direction in which light is guided. Furthermore, the projected length in the direction of guidance is preferably 10 mm to 50 mm, more preferably 12 mm to 45 mm, and even more preferably 15 mm to 40 mm. By using the light guide member of the present invention, it is possible to guide light while maintaining its polarization state, suppress the influence of the partial mirror of the present invention which has a reflectance difference of 10% or more between P-polarized and S-polarized light, and present a clear image to the observer.

[0057] Furthermore, the two waveguide surfaces may have partial mirrors formed on them that transmit a portion of the light and reflect the remaining portion. The partial mirrors may be formed on only one of the two waveguide surfaces, or on both. That is, partial mirrors that transmit a portion of the light and reflect the remaining portion may be formed on part or all of both sides of the two waveguide surfaces. When the partial mirrors are formed on only one of the two waveguide surfaces, it is preferable that the partial mirror that transmits a portion of the light and reflects the remaining portion is formed on the external waveguide surface.

[0058] (Input coupler) The input coupler according to this embodiment is not particularly limited as long as it is an element capable of guiding light into the light guide member without impairing the effects of the present invention. Examples of input couplers include surface relief type diffraction gratings, volume holograms, liquid crystal diffraction gratings, prism-shaped elements with an anti-reflective coating on some surfaces, and prism-shaped elements with partial mirrors, mirrors, polarizing beam splitters (including reflective polarizing elements) on some surfaces. By setting the angle of incidence in the reflection at the waveguide to be greater than or equal to the critical angle of the substrate portion of the light guide member or the outermost layer of the light guide member, light can be guided by total internal reflection, thereby reducing light loss. Furthermore, even when light is incident on the waveguide at an angle of incidence smaller than the critical angle, guidance that does not depend on the critical angle is possible by using the aforementioned optical elements or partial mirrors or mirrors. In particular, it is preferable to use an optical element with polarization selectivity that can maintain the polarization state as the input coupler for purposes such as improving light utilization efficiency and shielding some of the light. Here, polarization selectivity means that the polarization state of the light incident on the aforementioned optical element (the wavelength range used) has a diffraction efficiency, transmittance, or reflectance of 5% or more for either S-waves or P-waves compared to the other polarization.

[0059] (Output coupler) The output coupler according to this embodiment is not particularly limited as long as it is an element capable of guiding light within the light guide member without impairing the effects of the present invention. Examples of output couplers include surface relief type diffraction gratings, volume holograms, liquid crystal diffraction gratings, prism-shaped elements with an anti-reflective coating on some surfaces, and prism-shaped elements with a partial mirror, mirror, or polarizing beam splitter (including a reflective polarizing element) on some surfaces. Furthermore, the output coupler only needs to be configured to deliver some or all of the light guided through the waveguide to the observer's eyeball (eye point) by refraction, diffraction, or reflection. The shape of the output coupler is not limited to a flat surface, but may also have a curved surface, the functions of a convex or concave lens, and even a free-form surface. By adopting such a free-form surface, it is possible to construct a retinal direct-drawing optical system. In particular, for purposes such as improving light utilization efficiency or providing a function to shield some light, it is preferable to use an optical element with polarization selectivity that can maintain the polarization state in the output coupler. Furthermore, it is preferable that the output coupler has a partial mirror that transmits some of the light and reflects the remaining part.

[0060] [Characteristics of injection-molded light guide components] -Polarization retention properties- The polarization retention characteristics of the injection-molded light guide member in this embodiment can be evaluated by the following method. As a specific indicator, the ratio (Tp / Tc) of the light intensity (Tp) obtained by a power meter when light parallel to the optical axis of the light guide member and first polarized light is incident, and a polarizing plate positioned in front of the light extraction section to transmit the first polarized light, to the light intensity (Tc) obtained by a power meter under the condition that the polarizing plate positioned in front of the light emission section is rotated 90 degrees so that the first polarized light is blocked, is used as the standard. If there are multiple eye points, as shown in Figure 3, power meters are placed at multiple locations and the total light intensity is taken.

[0061] The following describes the preferred ratio (Tp / Tc) for each wavelength. Since this ratio (Tp / Tc) varies depending on the magnitude of (Rs / Rp), which is the ratio of the reflectance Rs for S-polarized light and the reflectance Rp for P-polarized light of the partial mirror, it is normalized by dividing it by the ratio (Rs / Rp) and used as an index. If there are multiple reflectance designs for the partial mirror, the value obtained by dividing (Tp / Tc) by the ratio (Rs / Rp) of the surface with the largest ratio of polarization reflectance (Rs / Rp) is used. When using a blue laser that emits light with a dominant wavelength of 450 nm, (Tp / Tc) / (Rs / Rp)(450 nm) is preferably 6 or greater. More preferably (Tp / Tc) / (Rs / Rp)(450 nm) is 12 or greater, even more preferably 18 or greater, and particularly preferably 30 or greater. Furthermore, when the polarization of the incident blue laser is S-polarized light, which vibrates on an axis perpendicular to the incident plane including the incident and reflected light, is incident on the light guide member, (Tp / Tc) / (Rs / Rp)(450nm) is preferably 7 or more, more preferably 10 or more, even more preferably 25 or more, and particularly preferably 40 or more. When the polarization of the incident blue laser is P-polarized light, which vibrates within the incident plane including the incident and reflected light, is incident on the light guide member, (Tp / Tc) / (Rs / Rp)(450nm) is preferably 5 or more, more preferably 7 or more, even more preferably 10 or more, and particularly preferably 15 or more.

[0062] When using a green laser that emits light with a dominant wavelength of 530 nm, (Tp / Tc) / (Rs / Rp)(530 nm) is preferably 10 or more. More preferably (Tp / Tc) / (Rs / Rp)(530 nm) is 15 or more, next preferably 20 or more, even more preferably 30 or more, and particularly preferably 40 or more. Furthermore, when the polarization of the incident green laser is S-polarized light, which vibrates on an axis perpendicular to the incident plane including the incident and reflected light, is incident on the light guide member, (Tp / Tc) / (Rs / Rp)(530nm) is preferably 10 or more, more preferably 50 or more, even more preferably 100 or more, and particularly preferably 300 or more. When the polarization of the incident green laser is P-polarized light that vibrates at the incident plane including the incident and reflected light is incident on the light guide member, (Tp / Tc) / (Rs / Rp)(530nm) is preferably 5 or more, more preferably 10 or more, even more preferably 20 or more, and particularly preferably 40 or more.

[0063] When using a red laser that emits light with a dominant wavelength of 630 nm, (Tp / Tc) / (Rs / Rp)(630 nm) is preferably 10 or more. More preferably (Tp / Tc) / (Rs / Rp)(630 nm) is 15 or more, even more preferably 20 or more, and particularly preferably 25 or more. Furthermore, when the polarization of the incident red laser is S-polarized light, which vibrates on an axis orthogonal to the incident plane including the incident and reflected light, is incident on the light guide member, (Tp / Tc) / (Rs / Rp)(630nm) is preferably 10 or more, more preferably 50 or more, even more preferably 100 or more, and particularly preferably 150 or more. When the polarization of the incident red laser is P-polarized light, which vibrates on an axis perpendicular to the incident plane including the incident and reflected light, is incident on the light guide member, (Tp / Tc) / (Rs / Rp)(630nm) is preferably 5 or more, more preferably 7 or more, even more preferably 10 or more, and particularly preferably 20 or more. By creating a light guide member with a high (Tp / Tc) ratio in this way, it becomes possible to display clear images without brightness unevenness, color unevenness, or rainbow effects. A light guide member with a high (Tp / Tc) ratio can be obtained by using a resin composition with excellent low birefringence properties, as described later, and manufacturing the light guide member by injection molding as described in the present invention.

[0064] - Reflectance difference between P-polarized and S-polarized light in a partial mirror - As one embodiment of the present invention, by using a light guide member with high polarization retention performance, for example, when a partial mirror having high reflectivity for S-polarized light is used in the waveguide and / or output coupler, it is possible to improve the light utilization efficiency by using a polarization light source element in the incident image and incident S-polarized image light on the reflective surface of the light guide member. In this case, the ratio (Rs / Rp) of the reflectance Rs of the first polarization, which is S-polarized at an incident angle of 30°, to the reflectance Rp of the second polarization, which is P-polarized and orthogonal to the first polarization, of the partial mirror formed in the waveguide and / or output coupler is preferably 1.2 or more, more preferably 1.4 or more, even more preferably 1.8 or more, and particularly preferably 3.0 or more. On the other hand, a ratio (Rs / Rp) of 9.0 or more is undesirable because it impairs the adhesion of the mirror. Therefore, it is preferable that the ratio (Rs / Rp) be less than 9.0.

[0065] Furthermore, for the partial mirror, it is preferable that the difference in reflectivity between the first polarization, which is S-polarized, and the second polarization, which is P-polarized, which is orthogonal to the first polarization, when reflected by the partial mirror at an incident angle of 30°, is 10% or more, more preferably 15% or more. Even more preferably it is 20% or more, and preferably 30% or more. However, if the difference in reflectivity is 40% or more, the adhesion of the mirror will deteriorate, which is undesirable, so it is preferable that it be less than 40%.

[0066] In a preferred embodiment of the present invention, one of the two waveguide surfaces is an external waveguide surface, and the external waveguide surface has a partial mirror formed thereon that transmits a portion of the light and reflects the remaining portion, wherein the difference in reflectance between a first polarization that becomes S polarization when reflected by the partial mirror at an incident angle of 30° and a second polarization that is P polarization, which is orthogonal to the first polarization, is 10% or more.

[0067] In another preferred embodiment, the output coupler has a partial mirror that transmits a portion of the light and reflects the remaining portion, wherein the difference in reflectivity between a first polarization that becomes S-polarized when reflected by the partial mirror at an incident angle of 30° and a second polarization that is P-polarized, which is orthogonal to the first polarization, is 10% or more.

[0068] Furthermore, if the output coupler is provided in a single stage, that is, if only one row of eye points is formed in the X-axis direction (multiple eye points may be present in the Y-axis direction), using a mirror with high S-polarization reflectivity in the light extraction section will prevent light from being extracted towards the eye. Therefore, it is preferable to use a mirror with low S-polarization and P-polarization reflectivity characteristics in either the light extraction section only, or in both the eye-side waveguide section and the light extraction section. Also, since light is often incident perpendicularly to the light extraction section when extracted towards the eye, it is preferable to use a partial mirror that has appropriate reflectivity at the incident angle when guiding the waveguide section, but low reflectivity at an incident angle of 0° when extracting light. Furthermore, in configurations where multiple output couplers are provided and multiple eye points are provided, this rule does not apply, and mirrors with a reflectivity higher than that of P-polarized light may be used in the eye-side waveguide and light extraction sections. In this case, it is preferable to appropriately adjust the reflectivity of the output coupler and the light extraction section so that the amount of light at each eye point is equal.

[0069] When the plane containing the incident and reflecting surfaces of the waveguide is horizontal to the ground, S-polarized light perpendicular to the incident / reflecting surfaces of the waveguide (polarized light vibrating in the Y-axis direction in Figure 4) becomes P-polarized light in the reflection of light from the ground (polarized light vibrating in the XY plane in Figure 5). Therefore, to reduce reflected light from objects or water surfaces, S-polarized light vibrating horizontally to the ground (on the incident / reflecting surfaces of the waveguide) In contrast, with the aim of shielding P-polarized light, S-polarized light from the ground is shielded in order from the outside. By arranging the polarizing plate in a straight line connecting the eye point (i.e., the observer's eyeball), the output coupler, and the outside world, the function of polarizing sunglasses can be provided (see Figure 6). In addition to the linear polarizer, a half-wavelength element or a phase difference layer that imparts a half-wavelength phase difference may also be used. In this case, by adjusting the reflectivity characteristics of the partial mirror and using a partial mirror with high S-polarization reflectivity relative to the waveguide in the output coupler or the external waveguide, and by using an image display element that emits S-polarized light (relative to the waveguide), it becomes possible to design a configuration that exhibits high transmittance for light incident from the outside through the linear polarizer and half-wavelength element (P-polarization relative to the incident / reflection surface of the waveguide), while exhibiting high reflectivity for image light guided within the light guide member (see Figure 7). As a phase difference layer that imparts a phase difference of half a wavelength, a thin film obtained by aligning and curing liquid crystal at a predetermined angle can be used.

[0070] In this embodiment, the injection-molded light guide member receives first polarization light with a wavelength of 500-600 nm, which becomes S-polarized upon reflection in the waveguide section, from the light incident section. After guiding the light in the waveguide section, when the light is extracted from the light output section via the output coupler, the ratio (Tp / Tc) of the transmittance Tp extracted through a polarizer arranged so that the axis of the first polarization coincides with the transmission axis, and the transmittance Tc extracted through a polarizer arranged so that the axis of the first polarization coincides with the transmission axis, divided by the ratio (Rs / Rp), which is the ratio of the reflectance Rs of the S-polarized light and the reflectance Rp of the P-polarized light of the partial mirror, is preferably 5 or more. Furthermore, the ratio (Tp / Tc) is preferably 10 or more, more preferably 15 or more, and even more preferably 20 or more. If there are multiple reflectance designs for the partial mirror, the value obtained by dividing (Tp / Tc) by the ratio (Rs / Rp) of the surface with the largest polarization reflectance ratio (Rs / Rp) is used.

[0071] -Evaluation based on video observation- The light guide member according to this embodiment can be used to evaluate the image being observed in the video using the method described in the embodiments below. For the evaluation of image observation, it is desirable to observe an image free from brightness unevenness, color unevenness, rainbows, and double images. By using the light guide member preferred in the present invention, as described later, it is possible to display an image free from brightness unevenness, color unevenness, rainbows, and double images.

[0072] -Phase difference within the effective area- In this embodiment, the light guide member has an average absolute value of the phase difference within the effective area when light is passed through the two waveguide surfaces from a vertical direction, i.e., the in-plane phase difference within the effective area guided by the waveguide is 20 nm or less, preferably 10 nm or less, more preferably 5 nm or less, and even more preferably 3 nm or less. By using a light guide member in which the average absolute value of the phase difference within the effective area is within this range, brightness unevenness, color unevenness, rainbow appearance, and ghosting (double image) in the case of long optical paths are suppressed, making it possible to view a clear and high-resolution image. Here, the effective area of ​​the light guide member refers to the region through which visible image light is transmitted (including wave guidance) when the light guide member is incorporated into the housing of the head-mounted display and an observer wearing the head-mounted display places their eyes within the designed eye box. This area is set as appropriate by the optical designer. Therefore, for components with protrusions or fitting mechanisms for integration into the housing, the parts of such protrusions and fitting mechanisms are excluded. If there is no clear effective area, the area including 80% or more of the projected area on the target surface is considered, excluding the areas of protrusions and fitting mechanisms. The projected area refers to the area of ​​the entire or partial region of the waveguide projected onto the horizontal plane when the surface under test of the light guide member is considered the upper surface, and parallel light rays parallel to the direction of gravity are irradiated from a point vertically above at infinity. Regarding methods for obtaining a light guide member with the effective area described above, a light guide member with an in-plane phase difference within the above range can be obtained by applying the preferred resin composition and preferred molding conditions described later. In addition, other methods include removing the gate and its surrounding region, which have large birefringences, from the light guide member and using it, or manufacturing it using a molded body that has been solidified by a photocuring or thermocuring reaction of monomer poured into a mold. However, the method of removing the gate and its surrounding region is undesirable because it results in large material losses and reduces the adjustment range during optical system assembly. Furthermore, the method of manufacturing a light guide member by a curing reaction has the problem of the long cycle time required to obtain one light guide member, and it is difficult to obtain a cured product without residual strain. For this reason, it is preferable to obtain the light guide member by injection molding.

[0073] -Surface accuracy- In this embodiment, the light guide member must accurately reproduce the surface shape specified in the optical design. If the surface shape deviates from the design, aberrations such as spherical aberration and astigmatism will occur, resulting in display image defects such as image distortion, overall image blurring, and localized image blurring. Preferred surface accuracy can be expressed by the PV value, which is the difference between the maximum and minimum values ​​representing the degree of deviation from the design shape. Preferably, the PV value in the effective area where light is guided is less than 15.0 μm for both waveguide surfaces. More preferably, the PV value is 10.0 μm, even more preferably 5.0 μm, and particularly preferably less than 3.0 μm. Furthermore, the surface shape is not limited to a flat surface; it can be a concave curved surface, a convex curved surface, a sphere, a free-form surface, or any other shape. Regardless of the type of curved surface, a light guide member with good surface accuracy can be obtained by using the suitable materials and molding methods shown in the present invention.

[0074] In a preferred embodiment of the present invention, the shortest distance between the two waveguide surfaces is 0.6 mm or more and 25 mm or less, the projected length of the light guide member in the direction of guidance is 10 mm or more and 50 mm or less, and the PV in the effective area where light is guided is 10.0 μm or less for both of the two waveguide surfaces.

[0075] -Glass transition temperature- In this embodiment, the light guide member preferably has a glass transition temperature (Tg) of 115°C to 150°C. A glass transition temperature of 115°C or higher for the light guide member is preferable because it ensures heat resistance against heat generated from the electronic components of the head-mounted display. Furthermore, a lower heat resistance temperature would result in larger dimensional changes in high-temperature environments, and when an optical film such as a polarizing film is laminated to the light guide member, there is a concern that peeling may occur due to differences in dimensional changes. In contrast, a higher heat resistance temperature is preferable because it also has the effect of suppressing photoelastic birefringence that occurs due to tension at the lamination interface with the optical film. The glass transition temperature (Tg) is more preferably 120°C or higher, even more preferably 125°C or higher, and most preferably 130°C or higher. In the injection molding process described later, the mold temperature during molding needs to be kept high, close to the glass transition temperature, in order to reduce the birefringence of the resin lens. Furthermore, when removing the resin light guide member, a long cooling time is necessary to suppress deformation such as sink marks. As a result, the cycle time becomes longer, and due to the rapid cooling caused by the temperature difference with room temperature, distortion tends to remain in the resin light guide member. Therefore, from the viewpoint of sufficiently reducing the birefringence of the light guide member, it is undesirable for the glass transition temperature of the light guide member to exceed 150°C in this embodiment. On the other hand, when the glass transition temperature (Tg) is 150°C or lower, melting processes at extremely high temperatures can be avoided, thermal decomposition of resins and other materials can be suppressed, and a good product can be obtained. From the viewpoint of obtaining the above-mentioned effects even more effectively, the glass transition temperature (Tg) is preferably 145°C or lower, and more preferably 140°C or lower. The glass transition temperature (Tg) can be determined by measurement in accordance with JIS-K7121. Specifically, it can be determined by the method described in the examples below. The glass transition temperature of the light guide member can be adjusted to the above range, for example, by producing the base material from the resin composition preferred in the present invention, as described later. The glass transition temperature can be increased by providing a ring structure to the main chain in the resin composition.

[0076] - Photoelastic coefficient CR- The light guiding member of this embodiment has an absolute value |CR| of the photoelastic coefficient CR of 10.0×10 -12 Pa -1 or less, preferably 5.0×10 -12 Pa -1 or less, more preferably 3.0×10 -12 Pa -1 or less, and even more preferably 1.0×10 -12 Pa -1 or less. There are descriptions in various documents regarding the photoelastic coefficient (see, for example, Chemistry Review, No. 39, 1998 (published by the Academic Publishing Center)), and it is defined by the following formulas (i-a) and (i-b). It can be seen that the closer the absolute value of the photoelastic coefficient CR is to zero, the smaller the change in birefringence due to an external force. |CR| = |Δn| / σR ···(i-a) |Δn| = |nx - ny| ···(i-b) (In the formula, CR represents the photoelastic coefficient, σR represents the tensile stress, |Δn| represents the absolute value of birefringence, nx represents the refractive index in the stretching direction, and ny represents the refractive index in the direction perpendicular to the stretching direction in the plane.) If the absolute value |CR| of the photoelastic coefficient CR of the light guiding member of this embodiment is 10.0×10 -12 Pa -1 or less, birefringence caused by internal strain generated during the molding of the light guiding member can be reduced, and furthermore, stress birefringence generated due to the stress generated when the light guiding member is fixed and adhered to a lens barrel or a jig is sufficiently small. In an optical device that uses polarized light, a resin lens can be obtained that suppresses the generation of ghosts and deterioration of contrast and provides a clear image. On the other hand, if the absolute value |CR| of the photoelastic coefficient CR is large, it causes birefringence and is not preferable because it causes uneven brightness, color unevenness, and rainbow appearance as described above. Note that after the light guiding member is cut into small pieces, the photoelastic coefficient CR can be measured by using a vacuum compression molding machine to form a press film. Specifically, it can be obtained by the method described in the examples below.

[0077] The absolute value of the photoelastic coefficient of the light guide member can be adjusted to the above range by, for example, producing the base portion of the light guide member from the resin composition preferred in this embodiment described later. When a homopolymer is formed, it is preferable to adjust the copolymerization composition ratio of monomers with a positive photoelastic coefficient and monomers with a negative photoelastic coefficient to an appropriate range. In the case of cyclic olefin copolymers, a cyclic olefin copolymer resin composition with a small absolute value of the photoelastic coefficient can be obtained by adjusting the copolymerization composition ratio of constituent units derived from α-olefins and constituent units derived from cyclic olefins to an appropriate range. It is also possible to relieve stress strain by annealing, but in order to sufficiently relieve the stress, it is necessary to perform heat treatment at a temperature from the glass transition temperature of the resin to a temperature close to the glass transition temperature, which is undesirable because the surface shape changes during this process and causes focal shifts, etc. Therefore, it is desirable to mold the light guide member from a resin composition with a small photoelastic coefficient.

[0078] -Light transmittance- The light guide member of this embodiment allows light to pass through the two waveguide surfaces from a vertical direction, and can be measured using a spectrophotometer in a D65 light source 2° field of view. Regarding light transmittance, the ratio of the transmittance at a wavelength of 450 nm (T450 / T680) to the transmittance at a wavelength of 680 nm (T680) is preferably 0.95 to 1.03, more preferably 0.97 to 1.01, and even more preferably 0.98 to 1.00. When the ratio (T450 / T680) is within the above range, an image with good color tone can be obtained. The light transmittance can be measured specifically by the method described in the examples below.

[0079] <Resin composition> In the light guide member of this embodiment, the base material is made of a resin composition. More specifically, the base material is made of a thermoplastic resin composition having a ring structure in the main chain or side chain. The resin composition is not particularly limited as long as it contains a thermoplastic resin that possesses both low birefringence and heat resistance properties so as to prevent rainbow-like appearance due to differences in the polarization reflectance of the partial mirror. However, it is preferable that the resin contains a methacrylic resin as it can achieve highly low birefringence properties. That is, the thermoplastic resin composition having a ring structure in the main chain or side chain is preferably a methacrylic resin composition, i.e., a methacrylic resin composition having a ring structure in the main chain or side chain. Furthermore, the thermoplastic resin composition having a ring structure in the main chain or side chain is also preferably a cyclic olefin copolymer resin composition containing a cyclic olefin copolymer. In summary, a thermoplastic resin composition having a ring structure in the main chain or side chain preferably contains a methacrylic resin or cyclic olefin copolymer having a ring structure in the main chain or side chain; that is, it is preferably a methacrylic resin composition or cyclic olefin copolymer resin composition containing a methacrylic resin having a ring structure in the main chain or side chain.

[0080] (Methacrylic resin) As a methacrylic resin, in order to ensure sufficient heat resistance, it is preferable to include a methacrylic resin having structural units (X) with a ring structure in the main chain and structural units derived from methacrylic acid ester monomers. By including a methacrylic resin, particularly a methacrylic resin containing structural units (X) with a ring structure in the main chain and methacrylic acid ester monomer units, it is possible to obtain a light guide member with high heat resistance, sufficiently small in-plane phase difference within the effective area, and sufficiently small photoelastic coefficient.

[0081] [Methacrylic resin having a ring structure in the main chain] The following describes the structural units of methacrylic resins, which have a ring structure in the main chain (X) and structural units derived from methacrylic acid ester monomers.

[0082] -Structural units derived from methacrylate monomers- Structural units derived from methacrylic acid ester monomers include, for example, structural units derived from monomers selected from the following methacrylic acid esters. Examples of methacrylic acid esters include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, cyclopentyl methacrylate, cyclohexyl methacrylate, cyclooctyl methacrylate, tricyclodecyl methacrylate, dicyclooctyl methacrylate, tricyclododecyl methacrylate, isobornyl methacrylate, phenyl methacrylate, benzyl methacrylate, 1-phenylethyl methacrylate, 2-phenoxyethyl methacrylate, 3-phenylpropyl methacrylate, and 2,4,6-tribromophenyl methacrylate. These monomers may be used individually or in combination of two or more. As for the structural units derived from the above-mentioned methacrylic acid ester monomers, it is preferable that they are structural units derived from methyl methacrylate and benzyl methacrylate, as these have excellent transparency and weather resistance in the resulting methacrylic resin. The structural unit derived from the methacrylate monomer may contain only one type, or two or more types.

[0083] By appropriately adjusting the ratio of structural units (X) having a ring structure in the main chain to structural units derived from methacrylic acid ester monomers in the methacrylic resin contained in the resin composition, it is possible to reduce birefringence caused by orientation and residual stress during molding, and to obtain a light guide member in which the absolute value of the in-plane phase difference within the effective area is 20 nm or less. Furthermore, by appropriately adjusting the above ratio, sufficient heat resistance can be imparted to the methacrylic resin. From these viewpoints, the content of structural units derived from methacrylic acid ester monomers is preferably 50 to 97% by mass, more preferably 55 to 97% by mass, even more preferably 55 to 95% by mass, even more preferably 60 to 93% by mass, and particularly preferably 60 to 90% by mass, with the methacrylic resin being 100% by mass. Furthermore, the content of structural units derived from methacrylate monomers is, 1 H-NMR measurement and 13 This can be determined by 13C-NMR measurement. 1 H-NMR measurement and 13 1C-NMR measurements can be performed, for example, using CDCl3 or DMSO-d6 as the measurement solvent and at a measurement temperature of 40°C.

[0084] -Structural unit (X) having a ring structure in the main chain- The following describes structural units (X) that have a ring structure in the main chain. The structural unit (X) having a ring structure in the main chain preferably includes at least one structural unit selected from the group consisting of structural units derived from N-substituted maleimide monomers, glutarimide-based structural units, and lactone ring structural units, and more preferably consists only of at least one structural unit selected from the group consisting of structural units derived from N-substituted maleimide monomers, glutarimide-based structural units, and lactone ring structural units. The structural unit (X) having a ring structure in the main chain may be one type or a combination of multiple types.

[0085] Furthermore, in other preferred application methods, the methacrylic resin preferably has at least one structural unit selected from the group consisting of structural units derived from N-substituted maleimide monomers, glutarimide-based structural units, lactone ring structural units, and aromatic ring hydrogenation structural units. In the case of methacrylic resins that undergo a cyclization process to introduce a ring structure into the main chain, there is a possibility that carboxylic acid side chains remain, which can cause a very high water absorption rate and adversely affect the adhesion of anti-reflective coatings and mirror coatings, as well as the adhesion when bonding with reflective polarizing elements. Therefore, methacrylic resins having structural units derived from N-substituted maleimide monomers or aromatic ring hydrogenation structural units are more preferable. In particular, having structural units derived from N-substituted maleimide monomers is especially preferable because it allows for a high degree of control over optical properties such as the photoelastic coefficient without blending with other thermoplastic resins. Furthermore, having an N-substituted maleimide monomer unit structure is particularly preferable because it allows for the acquisition of a ring structure that enhances heat resistance and controls low birefringence without going through a cyclization process that involves adding acids or bases that may inhibit adhesion to reflective polarizing elements.

[0086] --Structural units derived from N-substituted maleimide monomers-- Next, we will describe the structural units derived from N-substituted maleimide monomers. The structural unit derived from the N-substituted maleimide monomer may be at least one structural unit selected from the group consisting of the structural unit represented by the following general formula (1) and the structural unit represented by the following general formula (2), and preferably is formed from both the structural unit represented by the following general formula (1) and the following general formula (2).

[0087] [ka] In general formula (1), R 1 R represents either an arylalkyl group having 7 to 14 carbon atoms, or an aryl group having 6 to 14 carbon atoms. 2 and R 3 Each of these independently represents one of the following: a hydrogen atom, an oxygen atom, a sulfur atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 14 carbon atoms. Also, in general formula (1), R 2 or R 3 If it is an aryl group, R 2 or R 3 It may contain a halogen atom as a substituent. Also, in general formula (1), R 1 This may be substituted with substituents such as halogen atoms, C1-C6 alkyl groups, C1-C6 alkoxy groups, nitro groups, and benzyl groups.

[0088] [ka] In general formula (2), R 4 R represents a hydrogen atom, a cycloalkyl group having 3 to 12 carbon atoms, or an alkyl group having 1 to 12 carbon atoms. 5 and R 6 Each of these independently represents one of the following: a hydrogen atom, an oxygen atom, a sulfur atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 14 carbon atoms.

[0089] The following are specific examples of monomers that form structural units represented by general formulas (1) and (2). Examples of monomers that form the structural unit represented by general formula (1) (N-arylmaleimides, N-aromatically substituted maleimides, etc.) include N-phenylmaleimide, N-benzylmaleimide, N-(2-chlorophenyl)maleimide, N-(4-chlorophenyl)maleimide, N-(4-bromophenyl)maleimide, N-(2-methylphenyl)maleimide, N-(2,6-dimethylphenyl)maleimide, N-(2-ethylphenyl)maleimide, N-(2-methoxyphenyl)maleimide, N-(2-nitrophenyl) Examples include phenyl maleimide, N-(2,4,6-trimethylphenyl)maleimide, N-(4-benzylphenyl)maleimide, N-(2,4,6-tribromophenyl)maleimide, N-naphthylmaleimide, N-anthracenylmaleimide, 3-methyl-1-phenyl-1H-pyrrole-2,5-dione, 3,4-dimethyl-1-phenyl-1H-pyrrole-2,5-dione, 1,3-diphenyl-1H-pyrrole-2,5-dione, and 1,3,4-triphenyl-1H-pyrrole-2,5-dione. Among these monomers, N-phenylmaleimide and N-benzylmaleimide are preferred because the resulting methacrylic resin exhibits excellent heat resistance and optical properties such as birefringence. These monomers may be used individually or in combination of two or more.

[0090] Examples of monomers that form the structural unit represented by general formula (2) include N-methylmaleimide, N-ethylmaleimide, Nn-propylmaleimide, N-isopropylmaleimide, Nn-butylmaleimide, N-isobutylmaleimide, Ns-butylmaleimide, Nt-butylmaleimide, Nn-pentylmaleimide, Nn-hexylmaleimide, Nn-heptylmaleimide, Nn-octylmaleimide, and N Examples include lauryl maleimide, N-cyclopentyl maleimide, N-cyclohexyl maleimide, 1-cyclohexyl-3-methyl-1H-pyrrole-2,5-dione, 1-cyclohexyl-3,4-dimethyl-1H-pyrrole-2,5-dione, 1-cyclohexyl-3-phenyl-1H-pyrrole-2,5-dione, and 1-cyclohexyl-3,4-diphenyl-1H-pyrrole-2,5-dione. Of these monomers, N-methylmaleimide, N-ethylmaleimide, N-isopropylmaleimide, and N-cyclohexylmaleimide are preferred due to their excellent weather resistance as methacrylic resins, and N-cyclohexylmaleimide, which has an alicyclic group in its side chain, is particularly preferred because it exhibits excellent low hygroscopicity, which is required for optical materials in recent years. These monomers can be used individually or in combination of two or more types.

[0091] In the methacrylic resin of this embodiment, using both the structural unit represented by general formula (1) and the structural unit represented by general formula (2) in combination is particularly preferable for achieving highly controlled birefringence characteristics. The molar ratio (X1 / X2) of the content of structural units represented by formula (1) (X1) to the content of structural units represented by general formula (2) (X2) is preferably greater than 0 and less than or equal to 15, more preferably greater than 0 and less than or equal to 10. When the molar ratio (X1 / X2) is within this range, the light guide member of this embodiment maintains transparency, does not yellow, and exhibits good heat resistance and good photoelastic properties without impairing environmental resistance.

[0092] The content of structural units derived from N-substituted maleimide monomers is preferably in the range of 5 to 40% by mass, and more preferably in the range of 5 to 35% by mass, with the methacrylic resin being 100% by mass. When within this range, methacrylic resins exhibit more significant improvements in heat resistance, as well as more favorable improvements in weather resistance, low water absorption, and optical properties. Furthermore, limiting the content of structural units derived from N-substituted maleimide monomers to 40% by mass or less is effective in preventing a decrease in the physical properties of methacrylic resins due to reduced reactivity of monomer components during polymerization, resulting in a larger amount of unreacted monomers remaining. Furthermore, by appropriately adjusting the content of structural units derived from N-substituted maleimide monomers within this range, birefringence caused by orientation during molding and residual stress can be reduced, and a light guide member with an absolute value of in-plane phase difference of 20 nm or less within the effective area can be obtained. The optimal content of structural units derived from N-substituted maleimide monomers differs depending on the type of N-substituted maleimide, but for example, when methyl methacrylate is used as the methacrylate ester monomer and N-phenylmaleimide and N-cyclohexylmaleimide are used as the N-substituted maleimide monomers, it is preferable to adjust the content within the range of 79-83% by mass of structural units derived from methyl methacrylate, 6-8% by mass of structural units derived from N-phenylmaleimide, and 11-13% by mass of structural units derived from N-cyclohexylmaleimide.

[0093] N-substituted maleimides retain acidic components such as maleic acid and fumaric acid as by-products during the manufacturing process, but these acidic components can be sufficiently reduced during the purification process. Similarly, under high temperature and high humidity conditions during storage, hydrolysis occurs, generating acidic components such as maleic acid and fumaric acid as by-products. However, storing them in a cool, dark, and humidity-controlled environment suppresses the generation of these acidic components. Furthermore, methacrylic resins with N-substituted maleimides as the main chain do not require a cyclization process using acids or bases, offering the advantage of easier control over the residual amounts of acidic and alkaline components. Therefore, resins with controlled acidic content can be obtained.

[0094] In a resin composition, a methacrylic resin having structural units derived from an N-substituted maleimide monomer may contain structural units derived from a methacrylate monomer and structural units derived from other monomers copolymerizable with structural units derived from an N-substituted maleimide monomer, to the extent that it does not impair the objectives of the present invention. For example, other monomers that can be copolymerized include aromatic vinyls; unsaturated nitriles; acrylic acid esters having a cyclohexyl group, a benzyl group, or an alkyl group having 1 to 18 carbon atoms; glycidyl compounds; unsaturated carboxylic acids; and the like. Examples of the above-mentioned aromatic vinyls include styrene, α-methylstyrene, and divinylbenzene. Examples of the unsaturated nitriles mentioned above include acrylonitrile, methacrylonitrile, ethacrylonitrile, and the like. Examples of the above-mentioned acrylic acid esters include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, and butyl acrylate. Examples of the glycidyl compounds mentioned above include glycidyl (meth)acrylate. Examples of the above-mentioned unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and their semi-esterified or anhydrides. The structural units derived from the above copolymerizable monomers may consist of only one type, or two or more types.

[0095] The content of structural units derived from these copolymerizable monomers is preferably 0 to 10% by mass, more preferably 0 to 9% by mass, and even more preferably 0 to 8% by mass, with methacrylic resin being 100% by mass. Having structural units derived from other monomers within this range is preferable because it improves the moldability and mechanical properties of the resin without impairing the original effect of introducing ring structures into the main chain.

[0096] Furthermore, the content of structural units derived from N-substituted maleimide monomers, as well as the content of structural units derived from other copolymerizable monomers, 1H-NMR measurement and 13 This can be determined by 13C-NMR measurement. 1 H-NMR measurement and 13 1C-NMR measurements can be performed, for example, using CDCl3 or DMSO-d6 as the measurement solvent and at a measurement temperature of 40°C.

[0097] --Glutarimide structural units-- Examples of methacrylic resins having glutarimide-based structural units in the main chain include those described in Japanese Patent Publication No. 2006-249202, Japanese Patent Publication No. 2007-009182, Japanese Patent Publication No. 2007-009191, Japanese Patent Publication No. 2011-186482, and the republished Japanese Patent Publication No. 2012 / 114718, and can be formed by the methods described in said publications. The glutarimide-based structural units constituting the methacrylic resin of this embodiment may be formed after resin polymerization. Specifically, glutarimide structural units may be represented by the following general formula (3).

[0098] [ka] In the above general formula (3), preferably R 7 and R 8 Each is independently a hydrogen atom or a methyl group, and R 9 is one of a hydrogen atom, a methyl group, a butyl group, or a cyclohexyl group, and more preferably R 7 It is a methyl group, and R 8 R is a hydrogen atom, 9 This is a methyl group. The glutarimide structural unit may contain only one type or may contain multiple types.

[0099] In a methacrylic resin having glutarimide-based structural units, the content of glutarimide-based structural units is preferably in the range of 3 to 70% by mass, and more preferably in the range of 3 to 60% by mass, with the methacrylic resin being 100% by mass. When the content of glutarimide-based structural units is within the above range, it is preferable because a resin with good moldability, heat resistance, and optical properties can be obtained. Furthermore, by appropriately adjusting the content of glutarimide-based structural units within this range, it is possible to reduce birefringence caused by orientation and residual stress during molding, and obtain a light guide member with an absolute value of 20 nm or less in-plane phase difference within the effective area. R of general formula (3) 7 ~R 9 The optimal content of glutarimide-based structural units varies depending on the type of substituent, but for example, R 7 and R 8 is a hydrogen atom, R 9 When the group is a methyl group, if the glutarimide-based structural unit content is in the range of 3 to 10% by mass, it is possible to reduce birefringence caused by orientation or residual stress during molding and obtain a light guide member in which the absolute value of the in-plane phase difference within the effective area is 20 nm or less. Furthermore, the content of glutarimide-based structural units in methacrylic resins can be determined using the method described in the aforementioned patent document.

[0100] The methacrylic resin having glutarimide-based structural units may further contain aromatic vinyl monomer units as needed. The aromatic vinyl monomer is not particularly limited, but examples include styrene and α-methylstyrene, with styrene being preferred.

[0101] The content of aromatic vinyl units in the methacrylic resin having glutarimide-based structural units is not particularly limited, but is preferably 0 to 20% by mass, with the methacrylic resin having glutarimide-based structural units being 100% by mass. When the aromatic vinyl unit content is within the above range, it is preferable that both heat resistance and excellent photoelastic properties can be achieved. For example, when obtaining a resin by glutarimidating a methyl methacrylate-styrene copolymer obtained by copolymerizing methyl methacrylate as a methacrylate monomer and styrene as an aromatic vinyl monomer, adjusting the structural units within the range of 25-90% by mass derived from methyl methacrylate, 5-15% by mass derived from styrene, and 5-70% by mass derived from glutarimide-based structural units reduces birefringence caused by orientation and residual stress during molding, and makes it possible to obtain a light guide member with an absolute value of in-plane phase difference of 20 nm or less within the effective area. Furthermore, another effect is that by copolymerizing low-water-absorbing monomers such as styrene, it is possible to reduce the water absorption rate of the resulting methacrylic resin and the resin composition of said resin. This makes it possible to prevent delamination of reflective polarizing elements and suppress deterioration of lens surface accuracy after reliability tests in high-humidity environments.

[0102] --Lactone ring structural unit-- Methacrylic resins having lactone ring structural units in the main chain can be formed by methods described in, for example, Japanese Patent Publication No. 2001-151814, Japanese Patent Publication No. 2004-168882, Japanese Patent Publication No. 2005-146084, Japanese Patent Publication No. 2006-96960, Japanese Patent Publication No. 2006-171464, Japanese Patent Publication No. 2007-63541, Japanese Patent Publication No. 2007-297620, Japanese Patent Publication No. 2010-180305, etc.

[0103] The lactone ring structural units constituting the methacrylic resin of this embodiment may be formed after resin polymerization. In this embodiment, the lactone ring structural unit is preferably a 6-membered ring because it exhibits excellent stability in the ring structure. As a lactone ring structural unit having six members, the structure shown in the following general formula (4) is particularly preferred.

[0104] [ka] In the above general formula (4), R 10 , R 11 and R 12These are, independently of each other, a hydrogen atom or an organic residue having 1 to 20 carbon atoms. Examples of organic residues include saturated aliphatic hydrocarbon groups (alkyl groups, etc.) having 1 to 20 carbon atoms, such as methyl, ethyl, and propyl groups; unsaturated aliphatic hydrocarbon groups (alkenyl groups, etc.) having 2 to 20 carbon atoms, such as ethenyl and propenyl groups; aromatic hydrocarbon groups (aryl groups, etc.) having 6 to 20 carbon atoms, such as phenyl and naphthyl groups; and groups in which one or more hydrogen atoms in these saturated aliphatic, unsaturated aliphatic, or aromatic hydrocarbon groups are substituted with at least one group selected from the group consisting of hydroxyl, carboxyl, ether, and ester groups.

[0105] Lactone ring structural units can be formed, for example, by copolymerizing an acrylic acid monomer having a hydroxyl group with a methacrylic acid ester monomer such as methyl methacrylate to introduce a hydroxyl group and an ester group or carboxyl group into the molecular chain, and then causing de-alcoholization (esterification) or dehydration condensation (hereinafter also referred to as "cyclization condensation reaction") between these hydroxyl groups and the ester group or carboxyl group.

[0106] Examples of acrylic acid monomers having a hydroxyl group used in polymerization include 2-(hydroxymethyl)acrylic acid, 2-(hydroxyethyl)acrylic acid, alkyl 2-(hydroxymethyl)acrylate (e.g., methyl 2-(hydroxymethyl)acrylate, ethyl 2-(hydroxymethyl)acrylate, isopropyl 2-(hydroxymethyl)acrylate, n-butyl 2-(hydroxymethyl)acrylate, t-butyl 2-(hydroxymethyl)acrylate), and alkyl 2-(hydroxyethyl)acrylate. Preferably, the monomers having a hydroxyalkyl moiety are 2-(hydroxymethyl)acrylic acid or alkyl 2-(hydroxymethyl)acrylate, and particularly preferably methyl 2-(hydroxymethyl)acrylate and ethyl 2-(hydroxymethyl)acrylate.

[0107] In a methacrylic resin having lactone ring structural units in the main chain, the content of lactone ring structural units is preferably 5 to 40% by mass, and more preferably 5 to 35% by mass, based on 100% by mass of the methacrylic resin. When the lactone ring structural unit content is within this range, the ring structure introduction effect, such as improved solvent resistance and increased surface hardness, can be achieved while maintaining moldability. Furthermore, by appropriately adjusting the lactone ring structural unit content within this range, birefringence caused by orientation or residual stress during molding can be reduced, and a light guide member with an absolute value of 20 nm or less in-plane phase difference within the effective area can be obtained. The content of lactone ring structures in methacrylic resins can be determined using the method described in the aforementioned patent document.

[0108] A methacrylic resin having a lactone ring structural unit in its main chain may also have structural units derived from other monomers that can copolymerize with the structural units derived from the methacrylic acid ester monomers and the structural units derived from acrylic acid monomers having a hydroxyl group. Other monomers that can be copolymerized in this way include, for example, monomers having polymerizable double bonds such as styrene, vinyltoluene, α-methylstyrene, α-hydroxymethylstyrene, α-hydroxyethylstyrene, acrylonitrile, methacrylonitrile, metharyl alcohol, ethylene, propylene, 4-methyl-1-pentene, vinyl acetate, 2-hydroxymethyl-1-butene, methyl vinyl ketone, N-vinylpyrrolidone, and N-vinylcarbazole. These other monomers (constituent units) may consist of only one type or two or more types. In particular, by copolymerizing low-water-absorbing monomers such as styrene, it is possible to reduce the water absorption rate of the resulting methacrylic resin and the resin composition of said resin.

[0109] The content of these copolymerizable structural units derived from other monomers is preferably 0 to 20% by mass per 100% by mass of the methacrylic resin, more preferably less than 10% by mass, and even more preferably less than 7% by mass, from the viewpoint of weather resistance. The methacrylic resin in this embodiment may have only one structural unit derived from the above copolymerizable monomers, or it may have two or more.

[0110] --Methacrylic resin containing aromatic ring hydrogenation structural units-- Furthermore, as a methacrylic resin, methacrylic resins containing aromatic ring hydrogenation structural units are also preferred.

[0111] As a method for producing methacrylic resins having aromatic ring hydrogenation structural units, a method is used in which a copolymer of an aromatic vinyl compound and (meth)acrylate is hydrogenated in the presence of a hydrogenation catalyst and a reaction solvent to produce a nuclear hydrogenation polymer.

[0112] The following describes in detail an example of a method for producing a methacrylic resin containing aromatic ring hydrogenated structural units obtained by hydrogenating a copolymer of an aromatic vinyl compound and (meth)acrylate.

[0113] Examples of aromatic vinyl compounds used in polymerization include styrene, α-methylstyrene, vinyltoluene, α-hydroxymethylstyrene, α-hydroxyethylstyrene, p-hydroxystyrene, alkoxystyrene, and chlorostyrene, but styrene is preferred. It is also possible to copolymerize two or more aromatic vinyl compounds. Styrene with substituents at the α-position is particularly preferred because it can improve the heat resistance of the resin.

[0114] In the case of copolymers of aromatic vinyl compounds and (meth)acrylates, the composition of the copolymer's constituent units does not necessarily match the composition of the monomers used in the polymerization reaction. Instead, it is determined by the amount of monomer actually incorporated into the copolymer through the polymerization reaction. While the ratio of the copolymer's constituent units matches the composition ratio of the monomers used in the polymerization reaction if the polymerization rate is 100%, in reality, polymerization rates are often between 50% and 80%. Since more reactive monomers are more easily incorporated into the copolymer, a discrepancy arises between the composition of the monomers used in the polymerization reaction and the composition of the copolymer's constituent units. Therefore, it is necessary to adjust the composition ratio of the monomers used in the polymerization reaction as appropriate.

[0115] In the constituent units of the copolymer of an aromatic vinyl compound and (meth)acrylate used in the hydrogenation reaction of the present invention, the molar ratio (A / B) of constituent units derived from the (meth)acrylate monomer to constituent units (B moles) of the aromatic vinyl compound monomer is preferably 0.25 or more and 4.0 or less. If the molar ratio (A / B) is less than 0.25, the mechanical strength will be poor and it may not be practical. If the molar ratio (A / B) exceeds 4.0, there will be fewer aromatic rings to be hydrogenated, so the performance improvement effect, such as the improvement of the glass transition temperature due to the hydrogenation reaction, may be insufficient.

[0116] Furthermore, the methacrylic resin containing the aromatic ring hydrogenation structural unit may also contain structural units derived from other monomers copolymerizable with the aromatic ring hydrogenation structural unit, to the extent that it does not impair the objectives of the present invention. The content of these copolymerizable structural units derived from other monomers is preferably 0 to 20% by mass per 100% by mass of the methacrylic resin, more preferably less than 10% by mass, and even more preferably less than 7% by mass, from the viewpoint of weather resistance. The methacrylic resin in this embodiment may have only one structural unit derived from the above copolymerizable monomers, or it may have two or more.

[0117] -Methacrylic resin manufacturing method- The method for producing the methacrylic resin of this embodiment is described below.

[0118] --A method for producing methacrylic resins containing structural units derived from N-substituted maleimide monomers-- As a method for producing a methacrylic resin having structural units derived from N-substituted maleimide monomers in the main chain (hereinafter sometimes referred to as "maleimide copolymer"), any of the polymerization methods such as bulk polymerization, solution polymerization, suspension polymerization, precipitation polymerization, or emulsion polymerization can be used. From the viewpoint of reducing the amount of residual monomers and impurities contained in the light guide member, suspension polymerization, bulk polymerization, and solution polymerization are preferred, and solution polymerization is more preferred.

[0119] Regarding the method of adding the polymerization initiator, there are no particular restrictions as long as the addition rate is variable and adjusted to the concentration of monomers remaining in the polymerization solution, rather than being constant. It can be added continuously or intermittently. When adding the polymerization initiator intermittently, the amount added per unit time should not be considered for the time when no addition is being made.

[0120] In the manufacturing method of this embodiment, batch, semi-batch, and continuous polymerization methods can be used. Here, a batch method is a process in which the reaction is started and carried out after the entire amount of raw materials is added to the reactor, and the product is recovered after completion. A semi-batch method is a process in which either the addition of raw materials or the recovery of product is carried out simultaneously while the reaction is in progress, and a continuous method is a process in which both the addition of raw materials and the recovery of product are carried out simultaneously while the reaction is in progress. In this embodiment, it is preferable to use a method called semi-batch polymerization, in which a portion of the monomer is charged into the reactor before the start of polymerization, polymerization is started by adding a polymerization initiator, and then the remainder of the monomer is supplied, from the viewpoint of being able to precisely control the copolymer composition, reduce the amount of residual N-substituted maleimide at the end of polymerization, and reduce by-products of color and fluorescence emission. The continuous process is undesirable as a manufacturing method in this embodiment for the following reasons. When the polymerization reaction is carried out in a single complete mixing reactor, there is an advantage in that the difference in monomer composition between fractions with different molecular weights in the methacrylic resin can be reduced, but a large amount of unreacted monomers remain after polymerization, which tends to adversely affect the color. On the other hand, when a plug flow reactor is used, the amount of unreacted monomers can be reduced, but the difference in monomer composition between fractions with different molecular weights in the methacrylic resin tends to be larger. When multiple complete mixing reactors or a complete mixing reactor and a plug flow reactor are combined in series, the amount of unreacted monomers can be reduced, but the difference in monomer composition between each fraction tends to be larger.

[0121] In order to maintain good color tone and transmittance of light guide members obtained using methacrylic resins and compositions of said resins, and to reduce the content of fluorescent substances, it is preferable that the total mass of unreacted N-substituted maleimide remaining after polymerization is 1000 ppm by mass or less, and more preferably 10 ppm by mass or more and 500 ppm by mass or less, based on 100% by mass of the polymerization solution at the end of polymerization. Furthermore, when using N-arylmaleimides such as N-phenylmaleimide as the N-substituted maleimide, the total mass of unreacted N-arylmaleimides remaining after polymerization is preferably 500 ppm by mass or less, more preferably 10 ppm by mass or more and 500 ppm by mass or less, relative to 100% by mass of the polymerization solution at the end of polymerization. When the content is within these ranges, it is preferable because the content of fluorescent substances in the methacrylic resin and the resulting light guide member can be suppressed. Furthermore, in order to keep the amount of unreacted N-substituted maleimide below 10 ppm by mass, it is necessary to increase the polymerization temperature or increase the amount of polymerization initiator, which increases maleimide thermally modified products and active radicals, causing deterioration of the color tone of the methacrylic resin, and is therefore undesirable. One means of controlling the amount of unreacted N-substituted maleimide after polymerization to the above range is the semi-batch polymerization method. In the semi-batch polymerization method, in the polymerization process, it is preferable to add 5 to 35% by mass of methacrylic ester monomers, with the total mass of all monomers donated to polymerization (e.g., methacrylic acid ester, N-substituted maleimide, and any other monomers) being 100% by mass, 30 minutes or more after the start of addition of the polymerization initiator. In other words, it is preferable to charge 65 to 95% by mass of the total mass of all monomers to be donated to polymerization into the reactor before adding the polymerization initiator, and to add the remaining 5 to 35% by mass of methacrylate monomers 30 minutes or more after the start of addition of the polymerization initiator. The amount of methacrylate monomer to be added is more preferably 10 to 30% by mass, with the total mass of all monomers to be donated to polymerization being 100% by mass. It is preferable that the amount of methacrylate monomer to be added is within the above range because the unreacted N-substituted maleimide reacts with the added methacrylate monomer, and the amount of unreacted N-substituted maleimide after polymerization is controlled to be within the above range.

[0122] The starting point and speed of monomer addition can be appropriately selected according to the polymerization conversion rate. Furthermore, within a range that does not hinder the effects of the present invention and the reduction of unreacted N-substituted maleimide, a monomer mixture containing N-substituted maleimide monomers or other monomers may be added in addition to the methacrylate monomer. By employing the semi-batch polymerization method described above, it is possible to reduce the amount of unreacted N-substituted maleimide monomers in the latter half of polymerization, minimize the generation of fluorescent substances in the defoliation step described later, and obtain methacrylic resins and compositions of said resins that have good color tones even in light guide members with long optical path lengths, which is preferable.

[0123] The following describes in detail an example of a method for producing methacrylic resins having structural units derived from N-substituted maleimide monomers, specifically focusing on a semi-batch radical polymerization method using solution polymerization.

[0124] In the semi-batch polymerization method, it is preferable to add 5 to 35% by mass of methacrylate monomers, with the total mass of all monomers donated to polymerization (methacrylate ester, N-substituted maleimide, and any other monomers) being 100% by mass, 30 minutes or more after the start of polymerization initiator addition. In other words, it is preferable to charge 65 to 95% by mass of the total mass of all monomers donated to polymerization (100% by mass) into the reactor before polymerization starts, and to add the remaining 5 to 35% by mass of methacrylate monomers 30 minutes or more after the start of polymerization initiator addition. The amount of methacrylate monomer to be added is more preferably 10 to 30% by mass, with the total mass of all monomers donated to polymerization being 100% by mass.

[0125] The starting point and speed of monomer addition should be appropriately selected according to the polymerization conversion rate. Furthermore, insofar as it does not hinder the effects of the present invention and the conversion rate of the N-substituted maleimide monomer, a monomer mixture containing the N-substituted maleimide monomer or other monomers may be added in addition to the methacrylate monomer.

[0126] By employing the semi-batch polymerization method described above, it is possible to increase the conversion rate of N-substituted maleimide monomers in the later stages of polymerization, thereby reducing the content of fluorescent substances, resulting in a resin and a composition of the resin that exhibit excellent light transmittance in lenses with long optical path lengths, allow for easy control of the molecular weight distribution of the resulting polymer, and have particularly suitable fluidity for injection molding.

[0127] (Polymerization solvent) The polymerization solvent is not particularly limited as long as it provides high solubility for the maleimide copolymer obtained by polymerization and can appropriately maintain the viscosity of the reaction solution for purposes such as preventing gelation. Specific polymerization solvents that can be used include, for example, aromatic hydrocarbons such as toluene, xylene, ethylbenzene, and isopropylbenzene; esters such as methyl isobutyrate; ketones such as methyl isobutyl ketone, butyl cellosolve, methyl ethyl ketone, and cyclohexanone; and polar solvents such as dimethylformamide and 2-methylpyrrolidone. These can be used individually or in combination of two or more types. Furthermore, alcohols such as methanol, ethanol, and isopropanol may be used as polymerization solvents in combination, provided that they do not inhibit the dissolution of the polymerization product during polymerization.

[0128] The amount of solvent used during polymerization is not particularly limited as long as polymerization proceeds, and the copolymer and monomers used do not precipitate during production and can be easily removed. However, for example, if the total amount of monomers blended is 100% by mass, the amount of solvent is preferably 10 to 200% by mass, more preferably 25 to 200% by mass, even more preferably 50 to 200% by mass, and even more preferably 50 to 150% by mass. In this embodiment, a method of polymerization in which the amount of solvent during polymerization is appropriately changed during polymerization, within a range of 100% by mass or less when the total amount of monomers to be blended is 100% by mass, can also be preferably used. More specifically, one example of such a method is to incorporate 40-60% by mass in the initial stages of polymerization, then incorporate the remaining 60-40% by mass during polymerization, so that when the total amount of monomers incorporated is 100% by mass, the amount of solvent is within the range of 100% by mass or less. This method is preferable because it allows for an increase in polymerization conversion rate, further control of the molecular weight distribution, and the acquisition of resins and resin compositions with excellent injection moldability.

[0129] In solution polymerization, it is important to reduce the dissolved oxygen concentration in the polymerization solution as much as possible. For example, a dissolved oxygen concentration of 10 ppm or less is preferable. The dissolved oxygen concentration can be measured using, for example, a dissolved oxygen meter DO meter B-505 (manufactured by Iijima Electronics Industry Co., Ltd.). Methods to reduce the dissolved oxygen concentration can be appropriately selected from methods such as bubbling an inert gas into the polymerization solution, repeatedly pressurizing a container containing the polymerization solution with an inert gas to about 0.2 MPa before polymerization and then releasing the pressure, or passing an inert gas through a container containing the polymerization solution.

[0130] The polymerization temperature is not particularly limited as long as polymerization proceeds at that temperature, but it is preferably 70 to 180°C, more preferably 80 to 160°C, even more preferably 90 to 150°C, and even more preferably 100 to 150°C. From the viewpoint of productivity, it is preferable to set it to 70°C or higher, and to suppress side reactions during polymerization and to obtain a polymer with the desired molecular weight and quality, it is preferable to set it to 180°C or lower.

[0131] Furthermore, while there are no particular limitations on the polymerization time as long as it is sufficient to obtain the required degree of polymerization at the required conversion rate, from the viewpoint of productivity, it is preferably 2 to 15 hours, more preferably 3 to 12 hours, and even more preferably 4 to 10 hours.

[0132] (Polymerization initiator) As polymerization initiators, any initiator commonly used in radical polymerization can be used, such as organic peroxides including cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, benzoyl peroxide, t-butyl peroxyisopropyl carbonate, t-amyl peroxy-2-ethylhexanoate, t-amyl peroxyisononanoate, and 1,1-di(t-butylperoxy)cyclohexane; and azo compounds such as 2,2'-azobis(isobutyronitrile), 1,1'-azobis(cyclohexanecarbonile), 2,2'-azobis(2,4-dimethylvaleronitrile), and dimethyl-2,2'-azobisisobutyrate. These can be used individually or in combination of two or more types. These polymerization initiators may be added at any stage while the polymerization reaction is in progress. The amount of polymerization initiator added may be 0.01 to 1% by mass, preferably 0.05 to 0.5% by mass, when the total amount of monomers used for polymerization is considered to be 100% by mass. Regarding the method of adding the polymerization initiator, there are no particular restrictions as long as the addition rate is variable and adjusted to the concentration of monomers remaining in the polymerization solution, rather than being constant. It can be added continuously or intermittently. When adding the polymerization initiator intermittently, the amount added per unit time should not be considered for the time when no addition is being made.

[0133] In this embodiment, it is preferable to appropriately select the type and amount of polymerization initiator, as well as the polymerization temperature, so that the ratio of the total amount of radicals generated from the polymerization initiator to the total amount of unreacted monomers remaining in the reaction system is always below a certain value. By employing these methods, it is possible to suppress the generation of oligomers and low molecular weight products in the later stages of polymerization, and to improve the stability of polymerization by suppressing overheating during polymerization.

[0134] (Chain transfer agent) During the polymerization reaction, a chain transfer agent may be added as needed. As chain transfer agents, chain transfer agents commonly used in radical polymerization can be used, such as mercaptan compounds like n-butyl mercaptan, n-octyl mercaptan, n-decyl mercaptan, n-dodecyl mercaptan, and 2-ethylhexyl thioglycolate; halogen compounds like carbon tetrachloride, methylene chloride, and bromoform; and unsaturated hydrocarbon compounds like α-methylstyrene dimer, α-terpinene, dipentene, and terpinolene. These can be used individually or in combination of two or more types. These chain transfer agents can be added at any stage while the polymerization reaction is in progress, and are not particularly limited. The amount of chain transfer agent to add is preferably 0.05 to 0.5 parts by mass, based on a total amount of monomers used in polymerization of 100 parts by mass.

[0135] There are no particular limitations on the method for recovering polymers from a polymerization solution obtained by solution polymerization. For example, one method involves adding the polymerization solution to a poor solvent, such as a hydrocarbon or alcohol-based solvent, in which the polymerization product obtained by polymerization does not dissolve, followed by homogenization (emulsification and dispersion), and then separating the unreacted monomers from the polymerization solution by pretreatment such as liquid-liquid extraction or solid-liquid extraction. Alternatively, one method involves separating the polymerization solvent and unreacted monomers via a process called defoliation and recovering the polymerization product. Here, the defoliation process refers to the process of removing volatile components such as polymerization solvent, residual monomers, and reaction by-products under heating and reduced pressure conditions.

[0136] Examples of equipment used in the above devolatilization process include a devolatilization apparatus consisting of a tubular heat exchanger and a devolatilization tank. Other examples of equipment having rotating parts include thin-film evaporators such as the Wibren and Exceva manufactured by Kobe Steel Environmental Solutions Co., Ltd., and the Contra and Inclined-Blade Contra manufactured by Hitachi, Ltd., as well as vented extruders having sufficient residence time and surface area to exhibit devolatilization performance. A thawing process using a thawing apparatus that combines two or more of these devices can also be utilized.

[0137] For resin compositions constituting light guide members used in applications where high image contrast is important, it is crucial to suppress the generation of fluorescent reaction by-products. To suppress the generation of these by-products and obtain a methacrylic resin with good color tone, methods such as extending the polymerization time as much as possible to increase the monomer conversion rate, or changing the rate of addition of the polymerization initiator to match the concentration of unreacted monomers in the polymerization solution, can be used; polymerizing while appropriately changing the solvent concentration during polymerization; adding other monomers that are highly reactive with the remaining N-substituted maleimide monomers in the latter half of polymerization; or adding compounds that are highly reactive with N-substituted maleimide, such as α-terpinene, at the end of polymerization can be used.

[0138] From the standpoint of improving the color tone, it is preferable to use a davoltaic device that mainly consists of a heat exchanger and a vacuum vessel, and whose structure does not have a rotating part. Specifically, a devolatilization apparatus can be employed that consists of a devolatilization tank having a vacuum chamber with a heat exchanger positioned on top and a vacuum unit attached to a vacuum container large enough to perform devolatilization, and a discharge device such as a gear pump for discharging the polymer after devolatilization. The above-described devolatilization apparatus preheats the polymerization solution by subjecting it to a heated heat exchanger located at the top of a reduced-pressure vessel, such as a multi-tube heat exchanger, a plate-fin heat exchanger, or a plate-type heat exchanger having a plate-type channel and heater. After preheating, the solution is supplied to a devolatilization tank under heated and reduced pressure to separate and remove the polymerization solvent, unreacted raw material mixture, polymerization by-products, etc., from the copolymer. Using a devolatilization apparatus without a rotating part as described above is preferable because it allows for the acquisition of a methacrylic resin with a good color tone.

[0139] In this embodiment, it is preferable to use a flat-plate heat exchanger having a flat-plate channel and a heater as the heat exchanger to be placed at the top of the vacuum container. More preferably, it is a flat-plate heat exchanger having a stacked structure with a plurality of slit-shaped channels having a rectangular cross-section on the same plane and a heater.

[0140] The polymerization solution supplied to the defoliation device is sent from the center of the heat exchanger to the slit-shaped channel and heated. The heated polymerization solution is then supplied from the slit-shaped channel into a reduced-pressure container integrated with the heat exchanger, where it is flash-evaporated. This type of defoliation method is sometimes called flash defoliation, and in this invention, it will also be referred to as flash defoliation.

[0141] The polymerization solution supplied to the defoliation device is sent from the center of the heat exchanger to the slit-shaped channel and heated. The heated polymerization solution is then supplied from the slit-shaped channel into a reduced-pressure container integrated with the heat exchanger, where it is flash-evaporated. This type of defoliation method is sometimes called flash defoliation, and in this invention, it will also be referred to as flash defoliation.

[0142] The processing temperature in the defoliation apparatus is between the glass transition temperature (Tg) of the methacrylic resin + 100°C and the glass transition temperature (Tg) + 160°C. Specifically, the processing temperature is preferably 150 to 350°C, more preferably 180 to 310°C, and even more preferably 200 to 290°C. Setting the temperature above the lower limit suppresses residual volatile components, while setting it below the upper limit suppresses discoloration and decomposition of the resulting methacrylic resin.

[0143] The vacuum level in the defoliation tank can be in the range of 5 to 300 Torr, with a range of 10 to 200 Torr being preferable. A vacuum level of 300 Torr or less allows for efficient separation and removal of unreacted monomers or mixtures of unreacted monomers and polymerization solvent, without degrading the thermal stability and quality of the resulting thermoplastic copolymer. A vacuum level of 5 Torr or higher facilitates industrial implementation.

[0144] The average residence time in the defoliation tank is 5 to 60 minutes, preferably 5 to 45 minutes. A residence time within this range is preferable because it allows for efficient defoliation and suppresses discoloration and decomposition of polymers due to thermal denaturation.

[0145] The polymer recovered after the devolatilization process is processed into pellets in a process called granulation. In the granulation process, the molten resin is extruded into strands using at least one type of discharge granulation device selected from gear pumps, single-screw extruders, and twin-screw extruders, which have porous dies as ancillary equipment, and then processed into pellets using the cold-cut method, air-hot-cut method, underwater strand-cut method, and underwater-cut method.

[0146] In this embodiment, in order to obtain a highly controlled resin composition, it is preferable to employ a granulation method that allows for rapid cooling and solidification of the resin composition, which is in a molten state at high temperatures, while minimizing contact with air. In that case, it is preferable to perform granulation under conditions that allow for the lowest possible temperature of the molten resin, the shortest possible residence time from the porous die outlet to the cooling water surface, and the highest possible temperature of the cooling water. For example, the molten resin temperature is preferably 220 to 280°C, more preferably 230 to 270°C; the residence time from the porous die outlet to the cooling water surface is preferably 5 seconds or less, more preferably 3 seconds or less; and the cooling water temperature is preferably in the range of 30 to 80°C, more preferably 40 to 60°C.

[0147] By carrying out the process within these ranges of molten resin temperature and cooling water temperature, it is preferable to obtain methacrylic resins and compositions thereof that have less discoloration and a lower moisture content.

[0148] The amount of monomers remaining in the methacrylic resin after the defoliation process is preferable as it is lower, from the viewpoint of thermal stability and product quality. Specifically, the content of methacrylic acid ester monomers is preferably 3000 ppm by mass or less, and more preferably 2000 ppm by mass or less. The total content of N-substituted maleimide monomers is preferably 200 ppm by mass or less, and more preferably 100 ppm by mass or less. Furthermore, the residual polymerization solvent content is preferably 500 ppm by mass or less, and more preferably 300 ppm by mass or less.

[0149] --Methacrylic resin manufacturing method containing glutarimide structural units-- As a method for producing methacrylic resins having glutarimide-based structural units in the main chain, any of the polymerization methods such as bulk polymerization, solution polymerization, suspension polymerization, precipitation polymerization, or emulsion polymerization can be used, with suspension polymerization, bulk polymerization, or solution polymerization being preferred, and solution polymerization being even more preferred. In the manufacturing method of this embodiment, any of the following polymerization methods can be used: batch polymerization, semi-batch polymerization, or continuous polymerization. In the manufacturing method of this embodiment, it is preferable to polymerize the monomer by radical polymerization.

[0150] Methacrylic resins having glutarimide-based structural units in the main chain are, for example, those described in Japanese Patent Publication No. 2006-249202, Japanese Patent Publication No. 2007-009182, Japanese Patent Publication No. 2007-009191, Japanese Patent Publication No. 2011-186482, International Publication No. 2012 / 114718, etc., and can be formed by the methods described in said publications. The following describes in detail an example of a method for producing methacrylic resins having glutarimide-based structural units, specifically focusing on a batch-type radical polymerization method using solution polymerization.

[0151] First, a (meth)acrylic acid polymer is produced by polymerizing (meth)acrylic acid esters such as methyl methacrylate. When a methacrylic resin having glutarimide-based structural units contains aromatic vinyl units, a (meth)acrylic acid copolymer is produced by copolymerizing the (meth)acrylic acid ester with aromatic vinyl (e.g., styrene).

[0152] Examples of solvents used in polymerization include aromatic hydrocarbons such as toluene, xylene, and ethylbenzene; and ketones such as methyl ethyl ketone and methyl isobutyl ketone. These solvents may be used individually or in combination of two or more. The amount of solvent during polymerization is not particularly limited as long as polymerization proceeds, and the copolymer and monomers used do not precipitate during production and can be easily removed. However, for example, if the total amount of monomers blended is 100% by mass, the amount of solvent is preferably 10 to 200% by mass. The amount of solvent during polymerization is more preferably 25 to 200% by mass, even more preferably 50 to 200% by mass, and even more preferably 50 to 150% by mass.

[0153] The polymerization temperature is not particularly limited as long as polymerization proceeds at that temperature, but it is preferably 50 to 200°C, and more preferably 80 to 200°C. The polymerization temperature is even more preferably 90 to 150°C, even more preferably 100 to 140°C, and even more preferably 100 to 130°C. From the viewpoint of productivity, the polymerization temperature is preferably 50°C or higher, and it is preferable to keep it below 200°C to suppress side reactions during polymerization and to obtain a polymer with the desired molecular weight and quality. The polymerization time is not particularly limited as long as the desired conversion rate is achieved, but from the viewpoint of productivity, it is preferably 0.5 to 15 hours, more preferably 2 to 12 hours, and even more preferably 4 to 10 hours.

[0154] During the polymerization reaction, polymerization initiators or chain transfer agents may be added as needed.

[0155] The polymerization initiator is not particularly limited. For example, the polymerization initiators disclosed in the method for preparing a methacrylic resin having a structural unit derived from the above N-substituted maleimide monomer can be used. These polymerization initiators may be used alone or in combination of two or more. These polymerization initiators may be added at any stage as long as the polymerization reaction is in progress. The addition amount of the polymerization initiator may be appropriately set according to the monomer combination, reaction conditions, etc., and is not particularly limited. However, when the total amount of the monomers used for polymerization is 100% by mass, it may be 0.01 to 1% by mass, preferably 0.05 to 0.5% by mass.

[0156] As the chain transfer agent, a chain transfer agent used in general radical polymerization can be used. For example, the chain transfer agents disclosed in the column of the method for producing a methacrylic resin having a structural unit derived from the above N-substituted maleimide monomer can be used. These may be used alone or in combination of two or more. These chain transfer agents may be added at any stage as long as the polymerization reaction is in progress and are not particularly limited. The addition amount of the chain transfer agent is not particularly limited as long as the desired degree of polymerization can be obtained under the polymerization conditions used. However, preferably, when the total amount of the monomers used for polymerization is 100% by mass, it may be 0.01 to 1% by mass, preferably 0.05 to 0.5% by mass.

[0157] A suitable method for adding the polymerization initiator and the chain transfer agent in the polymerization step may be, for example, the method described in the method for preparing a methacrylic resin having a structural unit derived from the above N-substituted maleimide monomer. The dissolved oxygen concentration in the polymerization solution may be, for example, the value disclosed in the method for preparing a methacrylic resin having a structural unit derived from the above N-substituted maleimide monomer.

[0158] Next, an imidization reaction is carried out (imidization step) by reacting the above (meth)acrylate polymer or the above methacrylate-aromatic vinyl copolymer with an imidizing agent. Thereby, a methacrylic resin having a glutarimide-based structural unit can be produced.

[0159] The imidizing agent is not particularly limited as long as it can generate the glutarimide-based structural unit represented by the above general formula (3). Specifically, ammonia or a primary amine can be used as the imidizing agent. Examples of the primary amine include aliphatic hydrocarbon group-containing primary amines such as methylamine, ethylamine, n-propylamine, i-propylamine, n-butylamine, i-butylamine, tert-butylamine, and n-hexylamine; alicyclic hydrocarbon group-containing primary amines such as cyclohexylamine; and the like. Among the above imidizing agents, it is preferable to use ammonia, methylamine, or cyclohexylamine from the viewpoints of cost and physical properties, and it is particularly preferable to use methylamine.

[0160] In this imidization step, the content of the glutarimide-based structural unit in the obtained methacrylic resin having a glutarimide-based structural unit can be adjusted by adjusting the addition ratio of the imidizing agent.

[0161] The method for carrying out the above imidization reaction is not particularly limited, and a conventionally known method can be used. For example, the imidization reaction can be advanced by using an extruder or a batch-type reaction tank.

[0162] The extruder is not particularly limited. For example, a single-screw extruder, a twin-screw extruder, a multi-screw extruder, etc. can be used. Among them, it is preferable to use a twin-screw extruder. According to the twin-screw extruder, the mixing of the raw material polymer and the imidizing agent can be promoted. Examples of the twin-screw extruder include a non-intermeshing type co-rotating type, an intermeshing type co-rotating type, a non-intermeshing type counter-rotating type, an intermeshing type counter-rotating type, etc. The extruders exemplified above may be used individually or in series. Furthermore, it is particularly preferable to equip the extruder used with a vent that can reduce the pressure to below atmospheric pressure, as this allows for the removal of by-products such as the imidizing agent, methanol, or monomers from the reaction.

[0163] In producing methacrylic resins having glutarimide-based structural units, in addition to the imidation step described above, an esterification step may be included in which the carboxyl groups of the resin are treated with an esterifying agent such as dimethyl carbonate. In this case, catalysts such as trimethylamine, triethylamine, and tributylamine may also be used in combination. The esterification process can be carried out, similar to the imidation process described above, for example, by using an extruder or a batch-type reactor. Furthermore, to remove excess esterifying agents, by-products such as methanol, or monomers, it is preferable to equip the apparatus with a vent that can reduce the pressure to below atmospheric pressure. In this case, if the carboxyl groups are not esterified, the remaining carboxyl groups will increase the water absorption rate of the resin, leading to a deterioration of the surface accuracy of the light guide member in reliability tests under high humidity conditions. Also, if esterifying agents such as dimethyl carbonate or amines are not sufficiently defoliated, acidic or alkaline substances will remain, which is undesirable.

[0164] The methacrylic resin, after undergoing an imidization process and, if necessary, an esterification process, is melted and extruded in strand form from an extruder equipped with a porous die, and then processed into pellets using methods such as cold cutting, air hot cutting, underwater strand cutting, or underwater cutting. Furthermore, in order to reduce the number of foreign substances in the resin, it is also preferable to use a method in which the methacrylic resin is dissolved in an organic solvent such as toluene, methyl ethyl ketone, or methylene chloride, the resulting methacrylic resin solution is filtered, and then the organic solvent is devolved.

[0165] From the viewpoint of reducing fluorescence intensity (content of fluorescent substance), it is preferable to imidize the polymerization solution after polymerization is completed in a batch-type reaction vessel and to avoid using a twin-screw extruder that is subjected to shear force. The imidation reaction is preferably carried out at 130-250°C, more preferably at 150-230°C, and even more preferably at 170-190°C. The reaction time is preferably 10 minutes to 5 hours, and more preferably 30 minutes to 2 hours. After the imidization step, if necessary, an esterification step is performed, followed by defoliation using the defoliation method described in the method for preparing a methacrylic resin having structural units derived from the N-substituted maleimide monomer, and then pelletization, which is preferable from the viewpoint of reducing fluorescence intensity.

[0166] --Methacrylic resin manufacturing method containing lactone ring structural units-- As a method for producing methacrylic resins having lactone ring structural units in the main chain, a method is used in which the lactone ring structure is formed by a cyclization reaction after polymerization. In order to promote the cyclization reaction, it is preferable to polymerize the monomer by radical polymerization using a solution polymerization method with a solvent. In the manufacturing method of this embodiment, any of the following polymerization methods can be used: batch polymerization, semi-batch polymerization, or continuous polymerization. Methacrylic resins having lactone ring structural units in the main chain can be formed by methods described in, for example, Japanese Patent Publication No. 2001-151814, Japanese Patent Publication No. 2004-168882, Japanese Patent Publication No. 2005-146084, Japanese Patent Publication No. 2006-96960, Japanese Patent Publication No. 2006-171464, Japanese Patent Publication No. 2007-63541, Japanese Patent Publication No. 2007-297620, Japanese Patent Publication No. 2010-180305, etc.

[0167] Below, we will specifically describe an example of a method for producing methacrylic resins having lactone ring structural units, specifically a batch-type radical polymerization method using solution polymerization. As a method for producing methacrylic resins having lactone ring structural units, a method is used in which the lactone ring structure is formed by a cyclization reaction after polymerization. In order to promote the cyclization reaction, solution polymerization using a solvent is preferred.

[0168] Examples of solvents used in polymerization include aromatic hydrocarbons such as toluene, xylene, and ethylbenzene; and ketones such as methyl ethyl ketone and methyl isobutyl ketone. These solvents may be used individually or in combination of two or more.

[0169] There are no particular restrictions on the amount of solvent during polymerization, as long as the conditions allow polymerization to proceed and gelation to be suppressed. However, for example, if the total amount of monomers to be blended is 100% by mass, it is preferable to use 50 to 200% by mass, and more preferably 100 to 200% by mass.

[0170] To sufficiently suppress the gelation of the polymerization solution and promote the cyclization reaction after polymerization, it is preferable to carry out polymerization so that the concentration of the polymer produced in the reaction mixture obtained after polymerization is 50% by mass or less. Furthermore, it is preferable to appropriately add the polymerization solvent to the reaction mixture to control the concentration to 50% by mass or less.

[0171] The method of adding the polymerization solvent to the reaction mixture is not particularly limited; for example, the polymerization solvent may be added continuously or intermittently. The polymerization solvent added may be a single solvent or a mixture of two or more solvents. While there are no particular restrictions on the polymerization temperature as long as polymerization proceeds, from the viewpoint of productivity, it is preferably 50 to 200°C, and more preferably 80 to 180°C. The polymerization time is not particularly limited as long as the desired conversion rate is achieved, but from the viewpoint of productivity, it is preferably 0.5 to 10 hours, and more preferably 1 to 8 hours.

[0172] At the time of the polymerization reaction, a polymerization initiator or a chain transfer agent may be added as necessary to carry out the polymerization. The polymerization initiator is not particularly limited. For example, the polymerization initiators disclosed in the method for preparing a methacrylic resin having a structural unit derived from the above N-substituted maleimide monomer can be used. These polymerization initiators may be used alone or in combination of two or more. These polymerization initiators may be added at any stage as long as the polymerization reaction is in progress. The addition amount of the polymerization initiator may be appropriately set according to the monomer combination, reaction conditions, etc., and is not particularly limited. However, when the total amount of the monomers used for the polymerization is 100% by mass, it may be 0.05 to 1% by mass.

[0173] As the chain transfer agent, a chain transfer agent used in general radical polymerization can be used. For example, the chain transfer agents disclosed in the column of the method for producing a methacrylic resin having a structural unit derived from the above N-substituted maleimide monomer can be used. These may be used alone or in combination of two or more. These chain transfer agents may be added at any stage as long as the polymerization reaction is in progress, and are not particularly limited. The addition amount of the chain transfer agent is not particularly limited as long as the desired degree of polymerization can be obtained under the polymerization conditions used. However, preferably, when the total amount of the monomers used for the polymerization is 100% by mass, it may be 0.05 to 1% by mass.

[0174] A suitable method for adding the polymerization initiator and the chain transfer agent in the polymerization step may be, for example, the method described in the method for producing a methacrylic resin having a structural unit derived from the above N-substituted maleimide monomer.

[0175] The dissolved oxygen concentration in the polymerization solution may be, for example, the value disclosed in the method for producing a methacrylic resin having a structural unit derived from the above N-substituted maleimide monomer.

[0176] The methacrylic resin having a lactone ring structural unit in this embodiment can be obtained by carrying out a cyclization reaction after the polymerization reaction is completed. Therefore, it is preferable to carry out the lactone cyclization reaction with the polymerization solvent still present in the polymerization reaction solution, without removing the polymerization solvent. The copolymer obtained by polymerization undergoes a cyclization condensation reaction between the hydroxyl groups and ester groups present in the copolymer's molecular chains when heated, forming a lactone ring structure. During the heat treatment for lactone ring structure formation, a reaction apparatus equipped with a vacuum device or defoliation device to remove alcohols that may be produced as by-products by cyclization condensation, or an extruder equipped with a defoliation device, can also be used.

[0177] During lactone ring structure formation, if necessary, heat treatment using a cyclization condensation catalyst may be performed to promote the cyclization condensation reaction. Specific examples of cyclization condensation catalysts include, for example, monoalkyl esters, dialkyl esters, or triesters of phosphates such as methyl phosphite, ethyl phosphite, phenyl phosphite, dimethyl phosphite, diethyl phosphite, diphenyl phosphite, trimethyl phosphite, and triethyl phosphite; monoalkyl esters, dialkyl esters, or trialkyl esters of phosphates such as methyl phosphate, ethyl phosphate, 2-ethylhexyl phosphate, octyl phosphate, isodecyl phosphate, lauryl phosphate, stearyl phosphate, isostearyl phosphate, dimethyl phosphate, diethyl phosphate, di-2-ethylhexyl phosphate, diisodecyl phosphate, dilauryl phosphate, distearyl phosphate, diisostearyl phosphate, trimethyl phosphate, triethyl phosphate, triisodecyl phosphate, trilauryl phosphate, tristearyl phosphate, and triisostearyl phosphate; and organozinc compounds such as zinc acetate, zinc propionate, and zinc octyl. These can be used individually or in combination of two or more.

[0178] The amount of cyclization condensation catalyst used is not particularly limited, but for example, it is preferably 0.01 to 3% by mass, and more preferably 0.05 to 1% by mass, relative to 100% by mass of the methacrylic resin. Using 0.01% by mass or more of the catalyst is effective in improving the reaction rate of the cyclization condensation reaction, while using 3% by mass or less of the catalyst is effective in preventing the resulting polymer from becoming discolored or the polymer from becoming crosslinked, which would make melt molding difficult.

[0179] The timing of adding the cyclization condensation catalyst is not particularly limited; for example, it may be added at the beginning of the cyclization condensation reaction, during the reaction, or both. When carrying out a cyclization condensation reaction in the presence of a solvent, defoliation can also be performed simultaneously.

[0180] The apparatus used when carrying out the cyclization condensation reaction and the devolatilization process simultaneously is not particularly limited, but a devolatilization apparatus consisting of a heat exchanger and a devolatilization tank or a vented extruder is preferred, and a devolatilization apparatus and an extruder arranged in series is preferred, with a vented twin-screw extruder being more preferred. As the twin-screw extruder with vents to be used, a vented extruder having multiple vent ports is preferred.

[0181] When using a vented extruder, the reaction temperature is preferably 150 to 350°C, more preferably 200 to 300°C. If the reaction temperature is below 150°C, the cyclization condensation reaction may be insufficient, resulting in a large amount of residual volatile matter. Conversely, if the reaction temperature exceeds 350°C, discoloration and decomposition of the resulting polymer may occur. When using a vented extruder, the vacuum level is preferably 10 to 500 Torr, more preferably 10 to 300 Torr. If the vacuum level exceeds 500 Torr, volatile components may remain. Conversely, if the vacuum level is less than 10 Torr, industrial implementation may become difficult.

[0182] When carrying out the above cyclization condensation reaction, it is also preferable to add an alkaline earth metal and / or amphoteric metal salt of the organic acid during granulation in order to deactivate any remaining cyclization condensation catalyst. Examples of alkaline earth metal and / or amphoteric metal salts of organic acids include calcium acetylacetate, calcium stearate, zinc acetate, zinc octoate, and zinc 2-ethylhexylate.

[0183] After undergoing a cyclization condensation reaction, the methacrylic resin is melted and extruded in strand form from an extruder equipped with a porous die, and then processed into pellets using the cold cut method, air hot cut method, underwater strand cut method, and underwater cut method. Furthermore, the lactonization process for forming the aforementioned lactone ring structural units may be performed after the resin is manufactured but before the resin composition is manufactured (described later), or it may be performed during the manufacturing of the resin composition in conjunction with the melt-kneading of the resin with components other than the resin.

[0184] From the viewpoint of reducing fluorescence intensity (content of fluorescent substance), it is preferable to lactone cyclize the polymerization solution after polymerization in a batch-type reaction vessel and not to use a twin-screw extruder that is subjected to shear force. After the lactone cyclization step, it is preferable to defoliate using the defoliation method described in the method for preparing a methacrylic resin having structural units derived from the N-substituted maleimide monomer, and then pelletize, from the viewpoint of reducing fluorescence intensity.

[0185] --Methacrylic resin manufacturing method containing aromatic ring hydrogenation structural units-- As a method for producing methacrylic resins having aromatic ring hydrogenation structural units, a method is used in which a copolymer of an aromatic vinyl compound and (meth)acrylate is hydrogenated in the presence of a hydrogenation catalyst and a reaction solvent to produce a nuclear hydrogenation polymer. While known methods can be used to polymerize monomers containing aromatic vinyl compounds and (meth)acrylates, radical polymerization is industrially convenient and preferable. Radical polymerization can be carried out using known methods such as bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization, but it is preferable to produce the product by bulk polymerization or solution polymerization in order to avoid the inclusion of water during the hydrogenation reaction. In the production method of this embodiment, any of the polymerization methods, such as batch polymerization, semi-batch polymerization, or continuous polymerization, can be used. For example, a methacrylic resin containing aromatic ring hydrogenation structural units can be formed by the method described in Japanese Patent Publication No. 2006-291184, Japanese Patent Publication No. 2014-77043, Japanese Patent Publication No. 2014-77044, etc.

[0186] The following describes in detail an example of a method for producing a methacrylic resin containing aromatic ring hydrogenated structural units obtained by hydrogenating a copolymer of an aromatic vinyl compound and (meth)acrylate.

[0187] When selecting a solvent for polymerization, it is necessary to consider that the solvent itself is stable under the reaction conditions, and that the solubility of the copolymer (a copolymer of an aromatic vinyl compound and (meth)acrylate, and a nuclear hydrogenated polymer with a hydrogenated aromatic ring) and hydrogen before and after the hydrogenation reaction are good, as well as that the reaction proceeds rapidly. Furthermore, considering the defoliation of the solvent components after the reaction, a high flash point of the solvent is also important. Solvents that satisfy these requirements include hydrocarbon compounds such as n-pentane, n-hexane, n-octane, and cyclohexane; ether compounds such as 1,4-dioxane, tetrahydrofuran, ethylene glycol dimethyl ether, and diethylene glycol dimethyl ether; amide compounds such as dimethylformamide and dimethylacetamide; and ester compounds, but ether compounds and ester compounds are particularly preferred. Among ether compounds, tetrahydrofuran is particularly preferred. These solvents may be used individually or in combination of two or more.

[0188] Carboxylic acid ester compounds are preferred as ester compounds. Aliphatic ester compounds are used as carboxylic acid ester compounds, and compounds represented by the following general formula (5) are preferred. R 51 -COO-R 52 ...(5) In general formula (5), R 51 R is an alkyl group having 1 to 6 carbon atoms. 52 R is an alkyl group having 1 to 6 carbon atoms. 51 and R 52 Examples of these groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, hexyl, and cyclohexyl groups. Examples of ester compounds include methyl acetate, ethyl acetate, n-butyl acetate, pentyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, n-butyl propionate, methyl n-butyrate, methyl isobutyrate, n-butyrate-n-butyl, methyl n-valerate, and methyl n-hexanoate, but methyl acetate, ethyl acetate, methyl propionate, methyl isobutyrate, and methyl n-butyrate are particularly preferred.

[0189] The concentration of the copolymer (a copolymer of an aromatic vinyl compound and (meth)acrylate, and a nuclear hydrogenated polymer with a hydrogenated aromatic ring) in the solution during the hydrogenation reaction is usually 1 to 50% by weight, preferably 3 to 30% by weight, and more preferably 5 to 25% by weight. If the copolymer concentration is too high, it is undesirable in terms of a decrease in reaction rate and inconvenience of handling due to increased solution viscosity, while if the concentration is too low, it is undesirable in terms of productivity and economics.

[0190] The water content in the polymer solution before the hydrogenation reaction is 0.5% by weight or less, preferably 0.2% by weight or less, and more preferably 0.05% by weight or less. If the limit is exceeded, the manufactured nuclear hydrogenated polymer (pellets, powder) may become discolored, which is undesirable as an optical material.

[0191] During the polymerization reaction, polymerization initiators and chain transfer agents can be added as needed, but since sulfur inhibits the hydrogenation reaction, it is desirable to minimize sulfur content. The polymerization initiator is not particularly limited as long as it does not have a sulfur functional group, but for example, the polymerization initiator disclosed in the method for producing a methacrylic resin having structural units derived from the above-mentioned N-substituted maleimide monomer can be used. These polymerization initiators may be used individually or in combination of two or more. These polymerization initiators may be added at any stage while the polymerization reaction is in progress. The amount of polymerization initiator added can be set appropriately according to the combination of monomers and reaction conditions, and is not particularly limited, but it may be 0.05 to 1% by mass when the total amount of monomers used in polymerization is 100% by mass.

[0192] A suitable method for adding polymerization initiators and chain transfer agents in the polymerization process may be, for example, the method described in the method for preparing methacrylic resins having structural units derived from N-substituted maleimide monomers.

[0193] The dissolved oxygen concentration in the polymerization solution may be, for example, the value disclosed in the method for producing a methacrylic resin having structural units derived from the above-mentioned N-substituted maleimide monomer.

[0194] Chain transfer agents are not always necessary. If used, it is preferable to use tetrahalogenated carbons such as carbon tetrachloride, carbon tetrabromide, or carbon tetraiodide, or styrene dimers such as 2,4-diphenyl-4-methyl-1-pentene. Commonly used mercaptan compound-based chain transfer agents are undesirable because they introduce sulfur functional groups to the polymer ends, inhibiting the hydrogenation reaction of aromatic rings. These can be used individually or in combination of two or more types. These chain transfer agents can be added at any stage of the polymerization reaction, as long as the reaction is in progress, and are not particularly limited to any specific stage. The amount of chain transfer agent added is not particularly limited as long as it is within the range in which the desired degree of polymerization can be obtained under the polymerization conditions used. Preferably, it is 0.05 to 1% by mass when the total amount of monomers used for polymerization is 100% by mass. Generally, when mercaptan compound-based chain transfer agents are not used, the thermal decomposition properties of the raw polymer decrease. However, in methacrylic resins containing aromatic ring hydrogenation structural units, physical properties such as decomposition temperature depend solely on the hydrogenation rate, and if the hydrogenation rate is the same, the use of sulfur-based chain transfer agents does not affect the decomposition temperature.

[0195] Any catalyst with hydrogenation activity can be used as the catalyst (hydrogenation catalyst) in the hydrogenation reaction, and there are no particular restrictions. Specifically, examples include nickel, ruthenium, rhodium, palladium, and platinum. Among these, palladium supported on a carrier is particularly preferred because it has a high reaction rate and the solvent is retained before and after the reaction without undergoing side reactions. Generally, activated carbon, alumina (Al2O3), silica (SiO2), silica-alumina (SiO2-Al2O3), diatomaceous earth, and zirconium oxide are used as catalyst carriers. There are no restrictions on the catalyst carrier in the present invention, but activated carbon, alumina, or zirconium oxide is preferred.

[0196] The amount of palladium metal loaded onto the support is typically in the range of 0.01 to 50% by weight, preferably 0.05 to 20% by weight, and more preferably 0.1 to 10% by weight. Economically, it is preferable to use as little palladium as possible, as it is an expensive metal. However, when activated carbon or zirconium oxide is used as the support, it is possible to load palladium with high dispersion, and because the reaction rate per unit of palladium is very high, a sufficient reaction rate can be maintained even when the amount of palladium loaded is 0.1 to 1.0% by weight. When measuring the dispersion of palladium, known methods such as pulsed adsorption of carbon monoxide are used.

[0197] As palladium precursors, known salts or complexes of palladium chloride, palladium nitrate, palladium acetate, etc., can be used. When impregnating and supporting the precursor on a support, the precursor is prepared as a solution. Examples of precursor solution combinations (precursor / solvent) include palladium chloride / hydrochloric acid solution, palladium chloride / sodium chloride solution, palladium nitrate / water, palladium nitrate / hydrochloric acid solution, palladium acetate / hydrochloric acid solution, and palladium acetate / organic solvent.

[0198] The preferred conditions for hydrogenation reactions are a temperature of 60-250°C, a hydrogen pressure of 3-30 MPa, and a reaction time of 3-20 hours. If the reaction temperature is too low, the reaction rate will be slow, and if the reaction temperature is too high, side reactions such as polymer decomposition and solvent hydrolysis will occur, which is undesirable. Also, if the hydrogen pressure is too low, the reaction rate will be slow, and conversely, if the hydrogen pressure is increased further, a high-pressure reactor will be required, which is not economically desirable.

[0199] A nuclear hydrogenated polymer can be obtained by separating the hydrogenation catalyst and volatile components (solvent, etc.) from the polymer solution after the hydrogenation reaction. The catalyst can be separated by known methods such as filtration or centrifugation. Considering the effects on discoloration and mechanical properties, the residual catalyst metal concentration in the polymer should be kept as low as possible, preferably 10 ppm or less, and more preferably 1 ppm or less.

[0200] As a method for purifying the polymer by separating volatile components such as solvents from the nuclear hydrogenated polymer solution after separating the catalyst, it is preferable to defoliate it using the defoliation method described in the method for preparing methacrylic resins having structural units derived from N-substituted maleimide monomers, and then pelletize it.

[0201] <<Additives>> The resin composition constituting the light guide member of this embodiment may contain various additives, as long as they do not significantly impair the effects of the present invention. There are no particular restrictions on additives, but examples include antioxidants, light stabilizers such as hindered amine-based light stabilizers, ultraviolet absorbers, mold release agents, thermoplastic resins other than methacrylic resins, paraffinic process oils, naphthenic process oils, aromatic process oils, paraffin, organic polysiloxanes, mineral oils and other softeners / plasticizers, flame retardants, antistatic agents, organic fibers, inorganic fillers such as pigments such as iron oxide, reinforcing agents such as glass fibers, carbon fibers, and metal whiskers, colorants, organophosphorus compounds such as phosphite esters, phosphonites, and phosphate esters, and other additives or mixtures thereof.

[0202] -Antioxidant- The resin composition constituting the light guide member in this embodiment preferably contains an antioxidant that suppresses deterioration and discoloration during molding or use. The aforementioned antioxidants are not limited to the following, but examples include hindered phenol antioxidants, phosphorus antioxidants, sulfur antioxidants, etc. These antioxidants may be used individually or in combination of two or more types. Furthermore, from the viewpoint of improving thermal stability and suppressing molding defects, it is preferable to use multiple types of thermal stabilizers in combination. For example, it is preferable to use at least one selected from phosphorus-based antioxidants and sulfur-based antioxidants in combination with a hindered phenol-based antioxidant.

[0203] Hindered phenol antioxidants are not limited to the following, but include, for example, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], thiodiethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 3,3',3'',5,5',5''-hexa-tert-butyl-a,a',a''-(mesitylene-2,4,6-triyl)tri-p-cresol, 4,6-bis(octylthiomethyl)-o-cresol, 4,6-bis(dodecylthiomethyl)-o-cresol, ethylenebis(oxyethylene)bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate], hexamethylenebis[ 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1,3,5-tris[(4-tert-butyl-3-hydroxy-2,6-xyline)methyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 2 Examples include 6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazine-2-ylamine)phenol, 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate, and 2-tert-butyl-4-methyl-6-(2-hydroxy-3-tert-butyl-5-methylbenzyl)phenyl acrylate. In particular, pentaerythritol terakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, and 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate are preferred.

[0204] Furthermore, commercially available phenolic antioxidants may be used instead of hindered phenolic antioxidants. Such commercially available phenolic antioxidants are not limited to the following, but include, for example, Irganox 1010 (pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], manufactured by BASF) and Irganox 1076 (Irganox 1076: Octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate (BASF), Irganox 1330 (3,3',3'',5,5',5''-hexa-t-butyl-a,a',a''-(mesitylene-2,4,6-triyl)tri-p-cresol (BASF), Irganox 3114 (1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, B (Manufactured by ASF), Irganox 3125 (Manufactured by BASF), Adekastab AO-60 (Pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], Adekastab AO-80 (3,9-bis{2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionylxyoxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane, ADEKA), Sumilizer BHT Examples include BHT (manufactured by Sumitomo Chemical), Cyanox 1790 (manufactured by Cytec), Sumilizer GA-80 (manufactured by Sumitomo Chemical), Sumilizer GS (2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl acrylate]-4,6-di-tert-pentylphenyl acrylate, manufactured by Sumitomo Chemical), Sumilizer GM (2-tert-butyl-4-methyl-6-(2-hydroxy-3-tert-butyl-5-methylbenzyl)phenyl acrylate, manufactured by Sumitomo Chemical), and Vitamin E (manufactured by Eisai). Among these commercially available phenolic antioxidants, Irganox 1010, Adeka Stab AO-60, Adeka Stab AO-80, Irganox 1076, and Smirizer GS are preferred from the viewpoint of providing thermal stability to the resin. These can be used individually or in combination of two or more types.

[0205] Furthermore, the phosphorus-based antioxidants used as antioxidants are not limited to the following, but include, for example, tris(2,4-di-t-butylphenyl) phosphite, bis(2,4-bis(1,1-dimethylethyl)-6-methylphenyl) ethyl ester phosphorous acid, tetrakis(2,4-di-t-butylphenyl)(1,1-biphenyl)-4,4'-diylbisphosphonate, bis(2,4-di-t-butylphenyl) pentaerythritol diphosphite, and bis(2,6-di-t-butyl-4-methyl Examples include phenyl)pentaerythritol diphosphite, bis(2,4-dicumylphenyl)pentaerythritol-diphosphite, tetrakis(2,4-t-butylphenyl)(1,1-biphenyl)-4,4'-diylbisphosphonate, di-t-butyl-m-cresyl-phosphonate, and 4-[3-[(2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2]dioxaphosfepin)-6-yloxy]propyl]-2-methyl-6-tert-butylphenol.

[0206] Furthermore, commercially available phosphorus-based antioxidants may be used as phosphorus-based antioxidants. Such commercially available phosphorus-based antioxidants are not limited to the following, but include, for example, Irgafos 168 (tris(2,4-di-t-butylphenyl) phosphite, manufactured by BASF), Irgafos 12 (tris[2-[[2,4,8,10-tetra-t-butyldibenzo[d,f][1,3,2]dioxaphosphephine-6-yl]oxy]ethyl]amine, manufactured by BASF), Irgafos 38 (bis(2,4-bis(1,1-dimethylethyl)-6-methylphenyl) ethyl ester phosphorous acid, manufactured by BASF), Adekastab 329K (ADK STAB-229K, manufactured by ADEKA), and Adekastab PEP-36 (ADK STAB Sandstab P-EP-36 (made by ADEKA), ADK STAB PEP-36A (made by ADEKA), ADK STAB PEP-8 (made by ADEKA), ADK STAB HP-10 (made by ADEKA), ADK STAB 2112 (made by ADEKA), ADK STAB 1178 (made by ADEKA), ADK STAB 1500 (made by ADEKA), Sandstab P-EPQ (made by Clariant), Weston 618 (made by GE), Weston 619G (made by GE), Ultranox 626 (made by GE), Sumilizer GP Examples include GP:4-[3-[(2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2]dioxaphosfepine)-6-yloxy]propyl]-2-methyl-6-tert-butylphenol (manufactured by Sumitomo Chemical Co., Ltd.), HCA (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (manufactured by Sanko Co., Ltd.)). Among these commercially available phosphorus-based antioxidants, Irgaphos 168, Adekastab PEP-36, Adekastab PEP-36A, Adekastab HP-10, and Adekastab 1178 are preferred from the viewpoint of their effect in providing thermal stability to the resin and their effect in combination with various antioxidants, with Adekastab PEP-36A and Adekastab PEP-36 being particularly preferred. These phosphorus-based antioxidants may be used individually or in combination of two or more.

[0207] Furthermore, while not limited to the following, sulfur-based antioxidants include, for example, 2,4-bis(dodecylthiomethyl)-6-methylphenol (Irganox 1726, manufactured by BASF), 2,4-bis(octylthiomethyl)-6-methylphenol (Irganox 1520L, manufactured by BASF), and 2,2-bis{[3-(dodecylthio)-1-oxoporopoxy]methyl}propane-1,3-diyl Examples include bis[3-dodecylthio]propionate (ADEKA AO-412S), 2,2-bis{[3-(dodecylthio)-1-oxoporopoxy]methyl}propane-1,3-diylbis[3-dodecylthio]propionate (CHEMINOX PLS, CHEMINOX KASON COLOR), and di(tridecyl)3,3'-thiodipropionate (AO-503, ADEKA). Among these commercially available sulfur antioxidants, Adeka Stab AO-412S and Cheminox PLS are preferred from the viewpoint of their effect in providing thermal stability to the resin, their effectiveness in combination with various antioxidants, and their ease of handling. These sulfur-based antioxidants may be used individually or in combination of two or more.

[0208] The amount of antioxidant should be such that it provides an effect of improving thermal stability. If the amount is excessive, problems such as bleed-out may occur during processing. Therefore, it is preferable that the amount be 5 parts by mass or less, more preferably 3 parts by mass or less, even more preferably 1 part by mass or less, even more preferably 0.8 parts by mass or less, even more preferably 0.01 to 0.8 parts by mass, and particularly preferably 0.01 to 0.5 parts by mass per 100 parts by mass of methacrylic resin.

[0209] The antioxidant content should be such that it provides an effect of improving thermal stability. If the content is excessive, problems such as bleed-out may occur during processing. Therefore, it is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, even more preferably 0.8% by mass or less, even more preferably 0.01 to 0.8% by mass, and particularly preferably 0.01 to 0.5% by mass, based on 100% by mass of the methacrylic resin.

[0210] There are no particular limitations on the timing of adding the antioxidant. Examples include adding it to the monomer solution before polymerization and then starting the polymerization process, adding and mixing it to the polymer solution after polymerization and then subjecting it to the defoliation process, adding and mixing it to the molten polymer after defoliation and then pelletizing it, and adding and mixing it when the pellets are melted and extruded again after defoliation and pelletizing. Among these methods, it is preferable to add the antioxidant to the polymer solution after polymerization, mix it, and then add it before the defoliation process, in order to prevent thermal degradation and discoloration during the defoliation process.

[0211] -Hindered amine-based light stabilizers- The resin composition constituting the light guide member of this embodiment may contain a hindered amine-based light stabilizer. Hindered amine-based light stabilizers are not particularly limited, but are preferably compounds containing three or more ring structures. Here, the ring structures are preferably at least one selected from the group consisting of aromatic rings, aliphatic rings, aromatic heterocycles, and non-aromatic heterocycles, and if a compound has two or more ring structures, they may be the same or different from each other. Hindered amine-based light stabilizers are not limited to the following, but specifically include, for example, bis(1,2,2,6,6-pentamethyl-4-piperidyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate, a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, N ,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)-N,N'-diformylhexamethylenediamine, dibutylamine·1,3,5-triazine·N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)-1,6-hexamethylenediamine and N-(2,2,6,6-tetramethyl-4-piperidyl)butylamine polycondensate, poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl [-4-piperidyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidyl)imino}], tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylate, tetrakis(2,2,6,6-tetramethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylate, 1,2,2,6,6-pentamethyl-4-piperidiol and β,β,β',β'-tetramethyl-2,4,8,10-tetraoxaspiro[5 Reaction products of [5]undecane-3,9-diethanol, reaction products of 2,2,6,6-tetramethyl-4-piperidiol and β,β,β',β'-tetramethyl-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diethanol, bis(1-undecanoxy-2,2,6,6-tetramethylpiperidine-4-yl) carbonate, 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate, 2,2,6,6-tetramethyl-4-piperidyl methacrylate, etc. Among them, compounds containing three or more ring structures include bis(1,2,2,6,6-pentamethyl-4-piperidyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate, dibutylamine·1,3,5-triazine·N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)-1,6-hexamethylenediamine and N-(2,2,6,6-tetramethyl-4-piperidyl)butylamine polycondensate, poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4- The reaction product of diyl}{(2,2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidyl)imino}], 1,2,2,6,6-pentamethyl-4-piperidiol and β,β,β',β'-tetramethyl-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diethanol, and the reaction product of 2,2,6,6-tetramethyl-4-piperidiol and β,β,β',β'-tetramethyl-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diethanol are preferred. The amount of hindered amine-based light stabilizer should be such that it is effective in improving light stability. If the amount is excessive, problems such as bleed-out may occur during processing. Therefore, it is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, even more preferably 0.8% by mass or less, even more preferably 0.01 to 0.8% by mass, and particularly preferably 0.01 to 0.5% by mass, based on 100% by mass of the methacrylic resin.

[0212] - UV absorber - The resin composition may contain an ultraviolet absorber. While the ultraviolet absorber is not particularly limited, it is preferably an ultraviolet absorber having a maximum absorption wavelength of 280 to 380 nm. Examples of ultraviolet absorbers include benzotriazole compounds, benzotriazine compounds, benzophenone compounds, oxybenzophenone compounds, benzoate compounds, phenol compounds, oxazole compounds, cyanoacrylate compounds, and benzoxazinon compounds.

[0213] Examples of benzotriazole compounds include 2,2'-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazole-2-yl)phenol], 2-(3,5-di-tert-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole, 2-(2H-benzotriazole-2-yl)-p-cresol, 2-(2H-benzotriazole-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2-benzotriazole-2-yl-4,6-di-tert-butylphenol, 2-[5-chloro(2H)-benzotriazole-2-yl]-4-methyl-6-t-butylphenol, 2-(2H-benzotriazole-2-yl)-4,6-di-t-butylphenol, and 2-(2H-benzotriazole-2-yl)-4-(1,1 Examples include ,3,3-tetramethylbutyl)phenol, 2-(2H-benzotriazol-2-yl)-4-methyl-6-(3,4,5,6-tetrahydrophthalimidylmethyl)phenol, reaction products of methyl 3-(3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl)propionate / polyethylene glycol 300, 2-(2H-benzotriazol-2-yl)-6-(linear and side-chain dodecyl)-4-methylphenol, 2-(5-methyl-2-hydroxyphenyl)benzotriazole, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole, and 3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy-C7-9 side-chain and linear alkyl esters. Among these, benzotriazole compounds with a molecular weight of 400 or more are preferred. Examples of commercially available products include Kemisorb® 2792 (manufactured by Chemipro Chemical Co., Ltd.), Adeka Stab® LA31 (manufactured by ADEKA Corporation), and Chinuvin® 234 (manufactured by BASF). Examples of benzotriazine compounds include 2-mono(hydroxyphenyl)-1,3,5-triazine compounds, 2,4-bis(hydroxyphenyl)-1,3,5-triazine compounds, and 2,4,6-tris(hydroxyphenyl)-1,3,5-triazine compounds, specifically 2,4-diphenyl-6-(2-hydroxy-4-methoxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-ethoxyphenyl)-1,3,5-triazine, and 2,4-diphenyl-(2-hydroxy-4-propoxyphenyl) )-1,3,5-triazine, 2,4-diphenyl-(2-hydroxy-4-butoxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-butoxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-hexyloxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-octyloxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-dodecyloxyphenyl)-1,3,5-triazine, 2,4 -Diphenyl-6-(2-hydroxy-4-benzyloxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-butoxyethoxy)-1,3,5-triazine, 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-dibutoxyphenyl)-1,3-5-triazine, 2,4,6-tris(2-hydroxy-4-methoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-ethoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy(hydroxy) -4-propoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-butoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-butoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-hexyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-octyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-dodecyloxyphenyl)-1,3,5-triazine, 2,4,6-Tris(2-hydroxy-4-benzyloxyphenyl)-1,3,5-triazine, 2,4,6-Tris(2-hydroxy-4-ethoxyethoxyphenyl)-1,3,5-triazine, 2,4,6-Tris(2-hydroxy-4-butoxyethoxyphenyl)-1,3,5-triazine, 2,4,6-Tris(2-hydroxy-4-propoxyethoxyphenyl)-1,3,5-triazine, 2,4,6-Tris(2-hydroxy-4-methoxycarbonylpropyloxyphenyl)-1,3,5-triazine, 2,4,6-tri Tris(2-hydroxy-4-ethoxycarbonylethyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-(1-(2-ethoxyhexyloxy)-1-oxopropan-2-yloxy)phenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-methoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-ethoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4- (Propoxyphenyl)-1,3,5-triazine, 2,4,6-Tris(2-hydroxy-3-methyl-4-butoxyphenyl)-1,3,5-triazine, 2,4,6-Tris(2-hydroxy-3-methyl-4-butoxyphenyl)-1,3,5-triazine, 2,4,6-Tris(2-hydroxy-3-methyl-4-hexyloxyphenyl)-1,3,5-triazine, 2,4,6-Tris(2-hydroxy-3-methyl-4-octyloxyphenyl)-1,3,5-triazine, 2,4,6-Tris(2-hydroxy-3-methyl-4- Tris(2-hydroxy-3-methyl-4-benzyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-benzyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-ethoxyethoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-butoxyethoxyphenyl)-1,3,5-triazine, 2,4,Examples include 6-tris(2-hydroxy-3-methyl-4-methoxycarbonylpropyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-ethoxycarbonylethyloxyphenyl)-1,3,5-triazine, and 2,4,6-tris(2-hydroxy-3-methyl-4-(1-(2-ethoxyhexyloxy)-1-oxopropan-2-yloxy)phenyl)-1,3,5-triazine. As the benzotriazine compound, commercially available products may be used, such as Kemisorb 102 (manufactured by Chemipro Chemical Co., Ltd.), LA-F70 (manufactured by ADEKA Corporation), LA-46 (manufactured by ADEKA Corporation), Chinuvin 405 (manufactured by BASF), Chinuvin 460 (manufactured by BASF), Chinuvin 479 (manufactured by BASF), Chinuvin 1577FF (manufactured by BASF), etc. Among these, UV absorbers having a 2,4-bis(2,4-dimethylphenyl)-6-[2-hydroxy-4-(3-alkyloxy-2-hydroxypropyloxy)-5-α-cumylphenyl]-s-triazine skeleton (where "alkyloxy" refers to long-chain alkyloxy groups such as octyloxy, nonyloxy, and decyloxy) are even more preferably used due to their high compatibility with acrylic resins and excellent UV absorption properties.

[0214] As for ultraviolet absorbers, benzotriazole compounds and benzotriazine compounds with a molecular weight of 400 or more are particularly preferred from the viewpoint of compatibility with resins and volatility during heating, and benzotriazine compounds are particularly preferred from the viewpoint of suppressing decomposition of the ultraviolet absorber itself due to heating during extrusion processing.

[0215] Furthermore, the melting point (Tm) of the ultraviolet absorber is preferably 80°C or higher, more preferably 100°C or higher, even more preferably 130°C or higher, and even more preferably 160°C or higher. The UV absorber preferably has a weight loss rate of 50% or less when heated from 23°C to 260°C at a rate of 20°C / min, more preferably 30% or less, even more preferably 15% or less, even more preferably 10% or less, and even more preferably 5% or less. These UV absorbers may be used individually or in combination of two or more. By using two UV absorbers with different structures in combination, it is possible to absorb ultraviolet light across a wide wavelength range.

[0216] The amount of the UV absorber is not particularly limited as long as it does not impair heat resistance, heat and humidity resistance, thermal stability, and moldability, and exhibits the effects of the present invention. However, it is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 4 parts by mass, more preferably 0.25 to 3 parts by mass, and even more preferably 0.3 to 3 parts by mass, per 100 parts by mass of methacrylic resin. Within this range, an excellent balance of UV absorption performance, moldability, etc., is achieved.

[0217] -Release agent- The resin composition may contain a mold release agent. Examples of the mold release agent include, but are not limited to, fatty acid esters, fatty acid amides, fatty acid metal salts, hydrocarbon lubricants, alcohol lubricants, polyalkylene glycols, carboxylic acid esters, and hydrocarbon paraffinic mineral oils.

[0218] There are no particular restrictions on the fatty acid ester that can be used as the mold release agent; conventionally known ones can be used. Examples of fatty acid esters that can be used include ester compounds of fatty acids with 12 to 32 carbon atoms, such as lauric acid, palmitic acid, heptadecanoic acid, stearic acid, oleic acid, arachinic acid, and behenic acid, with monohydric aliphatic alcohols such as palmityl alcohol, stearyl alcohol, and behenyl alcohol, or polyhydric aliphatic alcohols such as glycerin, pentaerythritol, dipentaerythritol, and sorbitan; and complex ester compounds of fatty acids, polybasic organic acids, and monohydric or polyhydric aliphatic alcohols.

[0219] Examples of such fatty acid ester-based lubricants include cetyl palmitate, butyl stearate, stearyl stearate, stearyl citrate, glycerin monocaprylate, glycerin monocaprate, glycerin monolaurate, glycerin monopalmitate, glycerin dipalmitate, glycerin monostearate, glycerin distearate, glycerin tristearate, glycerin monooleate, glycerin dioleate, glycerin trioleate, and glycerin monolinoleate. Examples include glycerin monobehenate, glycerin mono-12-hydroxystearate, glycerin di-12-hydroxystearate, glycerin tri-12-hydroxystearate, glycerin diacetomostearate, glycerin triceto fatty acid ester, pentaerythritol adipate stearate, montanic acid partially saponified ester, pentaerythritol tetrastearate, dipentaerythritol hexastearate, sorbitan tristearate, etc. These fatty acid ester lubricants can be used individually or in combination of two or more. Examples of commercially available products include the Rikemar series, Poem series, Rikestar series, and Rikemaster series from Riken Vitamin Co., Ltd., and the Excel series, Leodor series, Excelpearl series, and Coconard series from Kao Corporation. More specifically, examples include Rikemar S-100, Rikemar H-100, Poem V-100, Rikemar B-100, Rikemar HC-100, Rikemar S-200, Poem B-200, Rikestar EW-200, Rikestar EW-400, Excel S-95, and Leodor MS-50.

[0220] There are no particular restrictions on fatty acid amides, and conventionally known types can be used. Examples of fatty acid amides include saturated fatty acid amides such as lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide; unsaturated fatty acid amides such as oleic acid amide, erucic acid amide, and ricinoleic acid amide; substituted amides such as N-stearyl stearate amide, N-oleyl oleic acid amide, N-stearyl oleic acid amide, N-oleyl stearate amide, N-stearyl erucic acid amide, and N-oleyl palmitic acid amide; methylol amides such as methylol stearate amide and methylol behenic acid amide; methylenebis-stearate amide, ethylene biscapric acid amide, ethylene bis-laurate amide, and ethylenebis-stearate amide (ethylene bis Examples include saturated fatty acid bisamides such as stearylamide, ethylenebisisostearate, ethylenebishydroxystearamide, ethylenebisbehenamide, hexamethylenebisstearate, hexamethylenebisbehenamide, hexamethylenebishydroxystearamide, N,N'-distearyladipamide, and N,N'-distearylsebacinamide; unsaturated fatty acid bisamides such as ethylenebisoleamide, hexamethylenebisoleamide, N,N'-dioleyladipamide, and N,N'-dioleylsebacinamide; and aromatic bisamides such as m-xylylenebisstearate and N,N'-distearylisophthalamide. These fatty acid amides can be used individually or in combination of two or more. Examples of commercially available products include the Diamid series (manufactured by Nippon Kasei Co., Ltd.), Amid series (manufactured by Nippon Kasei Co., Ltd.), Nikka Amid series (manufactured by Nippon Kasei Co., Ltd.), Methylol Amid series, Bis Amid series, Slipax series (manufactured by Nippon Kasei Co., Ltd.), Kaowax series (manufactured by Kao Corporation), Fatty Acid Amid series (manufactured by Kao Corporation), and Ethylene Bis-Stearic Acid Amides (manufactured by Dainichi Chemical Industry Co., Ltd.).

[0221] Fatty acid metal salts refer to metal salts of higher fatty acids, such as lithium stearate, magnesium stearate, calcium stearate, calcium laurate, calcium ricinoleate, strontium stearate, barium stearate, barium laurate, barium ricinoleate, zinc stearate, zinc laurate, zinc ricinoleate, zinc 2-ethylhexoate, lead stearate, dibasic lead stearate, lead naphthenate, calcium 12-hydroxystearate, and lithium 12-hydroxystearate. Among these, calcium stearate, magnesium stearate, and zinc stearate are particularly preferred because they produce transparent resin compositions with excellent processability and extremely high transparency. Examples of commercially available products include the SZ series, SC series, SM series, and SA series manufactured by Sakai Chemical Industry Co., Ltd. When using the above fatty acid metal salt, the content is preferably 0.2% by mass or less per 100% by mass of the resin composition, from the viewpoint of maintaining transparency.

[0222] The above-mentioned release agents may be used individually or in combination of two or more types.

[0223] The release agent used is preferably one with a decomposition initiation temperature of 200°C or higher. Here, the decomposition initiation temperature can be measured by the 1% mass loss temperature using TGA.

[0224] The amount of release agent should be such that it is effective as a release agent. If the amount is excessive, problems such as bleed-out and extrusion defects due to screw slippage may occur during processing. Therefore, it is preferable that the amount is 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, even more preferably 0.8% by mass or less, even more preferably 0.01 to 0.8% by mass, and particularly preferably 0.01 to 0.5% by mass, based on 100% by mass of the methacrylic resin. Adding the release agent in the above range is preferable because it suppresses the decrease in transparency due to the addition of the release agent and tends to suppress release defects during injection molding.

[0225] The amount of release agent should be such that it is effective as a release agent. If the amount is excessive, problems such as bleed-out and extrusion defects due to screw slippage may occur during processing. Therefore, it is preferable that the amount is 5 parts by mass or less per 100 parts by mass of methacrylic resin, more preferably 3 parts by mass or less, even more preferably 1 part by mass or less, even more preferably 0.8 parts by mass or less, even more preferably 0.01 to 0.8 parts by mass, and particularly preferably 0.01 to 0.5 parts by mass. Adding the release agent in the above range tends to suppress the decrease in transparency due to the addition of the release agent and to suppress mold release defects during injection molding.

[0226] In the case of mold release agents in which concerns such as bleed-out and screw slippage during processing are not observed even when the mold release agent content is increased, the amount added can be increased to allow it to act as a plasticizer. Specifically, it is possible to prepare a resin composition that contributes to improved fluidity during molding and has excellent moldability and transferability of fine shapes of thin-walled molded pieces. Furthermore, when performing an annealing process to reduce residual stress in molded products after molding, if the melting point Tm of the mold release agent is in the range of 30 to 80°C lower than the Tg of the resin composition, performing annealing at a temperature of about Tg-35 to 50°C allows the mold release agent to move in the same temperature range to promote stress relaxation, thereby reducing residual stress. Moreover, by performing the annealing process at a temperature range sufficiently lower than the Tg of the resin composition, it is possible to suppress deformation of the molded body, maintain surface accuracy after molding, and obtain a light guide member with good surface accuracy.

[0227] (Other thermoplastic resins) The resin composition constituting the light guide member of this embodiment may also contain other thermoplastic resins other than methacrylic resins for the purpose of adjusting birefringence and improving flexibility, without impairing the objectives of the present invention.

[0228] Other thermoplastic resins include, for example, polyacrylates such as polybutyl acrylate; styrene-based polymers such as polystyrene, styrene-butyl acrylate copolymer, styrene-acrylonitrile copolymer, and acrylonitrile-butadiene-styrene block copolymer; and, for example, acrylic rubber particles with a 3-4 layer structure as described in Japanese Patent Publication No. 59-202213, Japanese Patent Publication No. 63-27516, Japanese Patent Publication No. 51-129449, Japanese Patent Publication No. 52-56150, etc.; rubbery polymers disclosed in Japanese Patent Publication No. 60-17406 and Japanese Patent Publication No. 8-245854; and methacrylic rubber-containing graphite copolymer particles obtained by multi-stage polymerization as described in International Publication No. 2014-002491. Among these, from the viewpoint of obtaining good optical and mechanical properties, rubber-containing graft copolymer particles having a graft portion on their surface layer that is compatible with styrene-acrylonitrile copolymer or methacrylic resin containing a structural unit (X) having a ring structure in the main chain are preferred.

[0229] The average particle size of the aforementioned acrylic rubber particles, methacrylic rubber-containing graphite copolymer particles, and rubbery polymer is preferably 0.03 to 1 μm, and more preferably 0.05 to 0.5 μm, from the viewpoint of improving the impact strength and optical properties of the molded article obtained from the composition of this embodiment.

[0230] The content of other thermoplastic resins is preferably 0 to 50 parts by mass, and more preferably 0 to 25 parts by mass, when the methacrylic resin is 100 parts by mass.

[0231] (High-grade fatty acid esters) The resin composition preferably contains higher fatty acid esters.

[0232] By adding a specific amount of higher fatty acid ester to the resin composition, the desired function of the present invention can be achieved. Furthermore, it is preferable to use higher fatty acid esters that have two or fewer hydroxyl groups in their molecule. This is because it is possible to obtain optical components with low haze and good optical properties.

[0233] Furthermore, the content of higher fatty acid esters in the resin composition is preferably 0.5% by mass or more and 2.8% by mass or less, more preferably 0.6% by mass or more and 2.5% by mass or less, even more preferably 0.7% by mass or more and 1.7% by mass or less, and still more preferably 0.8% by mass or more and 1.3% by mass or less. By mixing the aforementioned higher fatty acid esters within the above range, the fluidity of the resin is dramatically improved, mitigating orientation birefringence. At the same time, the higher fatty acids move only at temperatures near their melting points, promoting relaxation of the resin side chains and contributing to the reduction of internal strain. Even in the annealing process, internal strain can be significantly reduced without degrading the surface shape. In addition, by controlling the formulation amount of the aforementioned higher fatty acid ester within the above range, foreign matter such as white haze and appearance defects during molding can be suppressed, and the shape accuracy of the molded product can be maintained at a high level. Furthermore, the occurrence of contamination of the mold insert mirror surface and clogging of the gas vent during molding can also be suppressed. For further information on higher fatty acid esters, please refer to the section on (higher fatty acid esters) described below.

[0234] <Cyclic Olefin Copolymer Resin Composition> The resin composition constituting the light guide member in this embodiment is also preferably a cyclic olefin copolymer resin composition. A cyclic olefin copolymer resin composition is a resin composition containing a cyclic olefin copolymer (hereinafter sometimes referred to as "cyclic olefin copolymer resin") which is a copolymer of ethylene or α-olefin and a cyclic olefin.

[0235] (Cyclic olefin copolymer) In this embodiment, the cyclic olefin copolymer, which includes a cyclic olefin as the ring structure of the main chain, includes a copolymer in which structural units derived from the cyclic olefin are essential constituent units. The cyclic olefin copolymer is preferably a copolymer of ethylene or α-olefin and a cyclic olefin.

[0236] The cyclic olefin copolymer contained in the cyclic olefin copolymer resin composition of this embodiment preferably contains at least one structural unit (b) derived from a cyclic olefin, selected from the group consisting of structural units represented by the following general formula (II), structural units represented by the following general formula (III), and structural units represented by the following general formula (IV). More preferably, from the viewpoint of further improving heat resistance and moldability while maintaining a good balance of transparency and refractive index performance of the resulting molded article, it contains at least one structural unit (a) derived from an olefin, represented by the following general formula (I), and at least one structural unit (b) derived from a cyclic olefin, selected from the group consisting of structural units represented by the following general formula (II), structural units represented by the following general formula (III), and structural units represented by the following general formula (IV).

[0237] [ka] In the above general formula (I), R 300 This represents a hydrogen atom or a linear or branched hydrocarbon group having 1 to 29 carbon atoms.

[0238] [ka] In the above general formula (II), u is 0 or 1, v is 0 or a positive integer, preferably an integer between 0 and 2, more preferably 0 or 1, w is 0 or 1, R 61 ~R 78 Furthermore, R a1 and R b1 These may be the same or different from each other, and are a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, a halogenated alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 15 carbon atoms, or an aromatic hydrocarbon group having 6 to 20 carbon atoms, R 75 ~R 78 These elements may be bonded to each other to form a monocycle or polycycle.

[0239] [ka] In the above general formula (III), x and d are integers of 0 or 1 or more, preferably integers of 0 or more and 2 or less, more preferably 0 or 1, and y and z are 0, 1 or 2, R 81 ~R 99 These may be the same or different from each other, and are a hydrogen atom, a halogen atom, an aliphatic hydrocarbon group which is an alkyl group having 1 to 20 carbon atoms or a cycloalkyl group having 3 to 15 carbon atoms, an aromatic hydrocarbon group which is an aromatic hydrocarbon group which is a 6 to 20 carbon atom or an alkoxy group, R 89 and R 90 The carbon atom to which it is bonded, and R 93 The carbon atom or R to which it is bonded 91 The carbon atom to which it is bonded may be directly bonded or bonded via an alkylene group having 1 to 3 carbon atoms, and when y=z=0, R 95 and R 92 or R 95 and R 99 These elements may be bonded to each other to form a monocyclic or polycyclic aromatic ring.

[0240] [ka] In the above general formula (IV), R 100 , R 101 These elements may be the same or different from each other, and represent a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms, where f is 1 ≤ f ≤ 18.

[0241] ((olefin monomer)) One of the copolymerization raw materials for the cyclic olefin copolymer according to this embodiment is an olefin monomer that undergoes addition copolymerization to form a structural unit represented by the above general formula (I). Specifically, olefin monomers represented by the following general formula (Ia), which corresponds to the above general formula (I), are used.

[0242] [ka] In the above general formula (Ia), R 300This represents a hydrogen atom or a linear or branched hydrocarbon group having 1 to 29 carbon atoms. Examples of olefin monomers represented by the above general formula (Ia) include ethylene or α-olefins, specifically ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, etc. Among these, it is preferable to use ethylene or propylene, and particularly preferable to use ethylene, from the viewpoint of obtaining a molded article with superior heat resistance, mechanical properties, and optical properties. Two or more types of olefin monomers represented by the above general formula (Ia) may be used.

[0243] In this embodiment, when the total amount of constituent units constituting the cyclic olefin copolymer is set to 100 mol%, the proportion of structural units derived from olefins is preferably 5 mol% to 95 mol%, more preferably 40 mol% to 85 mol%, even more preferably 50 mol% to 64 mol%, and particularly preferably 50 mol% to 62 mol%. Furthermore, the proportion of structural units derived from olefins is, 13 It can be measured by 13C-NMR.

[0244] ((Cyclic olefin monomer)) The cyclic olefin monomers constituting the cyclic olefin copolymer resin are not particularly limited. For example, the cyclic olefin monomers described in paragraphs

[0037] to

[0063] of International Publication No. 2006 / 0118261 can be cited.

[0245] The cyclic olefin monomer, which is one of the copolymerization raw materials for the cyclic olefin copolymer according to this embodiment, is preferably one that undergoes addition copolymerization to form a structural unit (b) derived from a cyclic olefin represented by the above general formula (II), the above general formula (III), or the above general formula (IV). Specifically, cyclic olefin monomers represented by general formulas (IIa), (IIIa), and (IVa), which correspond to the above general formulas (II), (III), and (IV), respectively, are used.

[0246] [ka]

[0247] In the above general formula (IIa), u is 0 or 1, v is 0 or a positive integer, preferably an integer between 0 and 2, more preferably 0 or 1, w is 0 or 1, R 61 ~R 78 Furthermore, R a1 and R b1 These may be the same or different from each other, and are a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, a halogenated alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 15 carbon atoms, or an aromatic hydrocarbon group having 6 to 20 carbon atoms, R 75 ~R 78 These elements may be bonded to each other to form a monocycle or polycycle.

[0248] [ka]

[0249] In the above general formula (IIIa), x and d are integers of 0 or 1 or more, preferably integers of 0 or more and 2 or less, more preferably 0 or 1, and y and z are 0, 1 or 2, R 81 ~R 99may be the same as or different from each other, and is a hydrogen atom, a halogen atom, an aliphatic hydrocarbon group that is an alkyl group having 1 to 20 carbon atoms or a cycloalkyl group having 3 to 15 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms or an alkoxy group, R 89 and R 90 The carbon atom to which is bonded, R 93 The carbon atom to which is bonded or R 91 The carbon atom to which is bonded may be bonded directly or via an alkylene group having 1 to 3 carbon atoms, and when y = z = 0, R 95 and R 92 or R 95 and R 99 and may be bonded to each other to form a monocyclic or polycyclic aromatic ring.

[0250]

Chemical formula

[0251] In the above general formula (IVa), R 100 , and R 101 may be the same as or different from each other, and represent a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms, and f satisfies 1 ≦ f ≦ 18.

[0252] As the copolymerization component, by using the olefin monomer represented by the above general formula (Ia) and the cyclic olefin monomer represented by the general formula (IIa), (IIIa) or (IVa), the solubility of the cyclic olefin copolymer (A) in a solvent is further improved, so that the moldability becomes good and the product yield is improved.

[0253] Regarding specific examples of the cyclic olefin monomer represented by the general formula (IIa), (IIIa) or (IVa), the compounds described in paragraphs

[0037] to

[0063] of International Publication No. 2006 / 0118261 can be used.

[0254] Specifically, bicyclo-2-heptene derivatives (bicyclohept-2-ene derivatives), tricyclo-3-decene derivatives, tricyclo-3-undecene derivatives, tetracyclo-3-dodecene derivatives, pentacyclo-4-pentadecene derivatives, pentacyclopentadecadiene derivatives, pentacyclo-3-pentadecene derivatives, pentacyclo-4-hexadecene derivatives, pentacyclo-3-hexadecene derivatives, hexacyclo-4-heptadecene derivatives, heptacyclo-5-eicosene Examples include derivatives, heptacyclo-4-eicosene derivatives, heptacyclo-5-heneicosene derivatives, octacyclo-5-docosene derivatives, nonacyclo-5-pentacosene derivatives, nonacyclo-6-hexacosene derivatives, cyclopentadiene-acenaphthylene adducts, 1,4-methano-1,4,4a,9a-tetrahydrofluorene derivatives, 1,4-methano-1,4,4a,5,10,10a-hexahydroanthracene derivatives, and cycloalkylene derivatives having 3 to 20 carbon atoms.

[0255] Furthermore, among the cyclic olefin monomers represented by general formulas (IIa), (IIIa), or (IVa), the cyclic olefin monomer represented by general formula (IIa) is preferred. Examples of cyclic olefin monomers represented by the above general formula (IIa) include bicyclo[2.2.1]-2-heptene (also called "norbornene") and tetracyclo[4.4.0.1 2,5 .1 7,10 It is preferable to use ]-3-dodecene (also called tetracyclododecene), and tetracyclo[4.4.0.1 2,5 .1 7,10 It is more preferable to use ]-3-dodecene. These cyclic olefins have a rigid ring structure, which has the advantage of making it easier to maintain the elastic modulus of the copolymer and molded article.

[0256] When the total amount of structural units constituting the main chain of the cyclic olefin copolymer is taken as 100 mol%, the proportion of structural units (ring skeleton structural units) derived from the cyclic olefin monomer is preferably 5 mol% to 95 mol%, more preferably 15 mol% to 60 mol%, even more preferably 36 mol% to 50 mol%, and particularly preferably 38 mol% to 50 mol%. By keeping the structural units derived from cyclic olefin monomers within the above range, high heat resistance is achieved, and a high modulus of elasticity is maintained, especially in high-temperature regions. This suppresses shape deformation during the annealing process and minimizes surface deformation of the light guide member of the present invention.

[0257] The molecular weight of the cyclic olefin copolymer according to this embodiment is not particularly limited, but is preferably such that the intrinsic viscosity [η] measured in decalin at 135°C is 0.03 dl / g to 10 dl / g, more preferably 0.05 dl / g to 5 dl / g, and even more preferably 0.10 dl / g to 2 dl / g. If the molecular weight of the cyclic olefin copolymer is above the lower limit mentioned above, the mechanical strength of the molded article can be improved. Furthermore, if the molecular weight is below the upper limit mentioned above, the moldability can be improved.

[0258] (High-grade fatty acid esters) The cyclic olefin copolymer resin composition according to this embodiment preferably contains a higher fatty acid ester in addition to the cyclic olefin copolymer described above.

[0259] By adding a specific amount of higher fatty acid ester to the cyclic olefin copolymer resin composition according to this embodiment, the desired function of the present invention can be achieved. Furthermore, it is preferable to use higher fatty acid esters that have two or fewer hydroxyl groups in their molecule. This is because it is possible to obtain optical components with low haze and good optical properties.

[0260] Furthermore, the content of higher fatty acid esters in the cyclic olefin copolymer resin composition according to this embodiment is preferably 0.5% by mass or more and 2.8% by mass or less, more preferably 0.6% by mass or more and 2.5% by mass or less, even more preferably 0.7% by mass or more and 1.7% by mass or less, and still more preferably 0.8% by mass or more and 1.3% by mass or less. By mixing the aforementioned higher fatty acid esters within the above range, the fluidity of the resin is dramatically improved, mitigating orientation birefringence. At the same time, the higher fatty acids move only at temperatures near their melting points, promoting relaxation of the resin side chains and contributing to the reduction of internal strain. Even in the annealing process, internal strain can be significantly reduced without degrading the surface shape. In addition, by controlling the formulation amount of the aforementioned higher fatty acid ester within the above range, foreign matter such as white haze and appearance defects during molding can be suppressed, and the shape accuracy of the molded product can be maintained at a high level. Furthermore, the occurrence of contamination of the mold insert mirror surface and clogging of the gas vent during molding can also be suppressed.

[0261] Here, the higher fatty acid ester is an ester compound consisting of a fatty acid having 6 or more carbon atoms and an alcohol. The higher fatty acid ester according to this embodiment consists of the following polyhydric alcohol and fatty acid. The aforementioned polyhydric alcohols include glycerin, pentaerythritol, diglycerin, triglycerin, polyglycerin, 1,2-ethanediol, dipentaerythritol, sorbitan, polyethylene glycol, polypropylene glycol, polybutylene glycol, α,α'-[(isopropylidene)di-4,1-phenylene]bis{ω-hydroxy-poly[oxy(methylethylene)]}, polyoxyethylene-laurylamine, polyoxyethylene-stearylamine, polyoxyethylene-oleylamine, polyoxyethylene-polyoxypropylene-pentaerythritol ether, polyethylene glycol-polybutylene glycol-pentaerythritol ether, polyoxytetramethylene-polyoxyethylene glycol, polyoxytetramethylene-polyoxypropylene glycol, trimethylolpropane-tris(polyoxytetramethylene-polyoxypropylene) ether Examples include ether, polyoxyethylene-bisphenol A ether, polyoxypropylene-bisphenol A ether, polyoxyethylene-polyoxypropylene-bisphenol A ether, 1-thioglycerol, polyoxypropylene diglyceryl ether, polyoxypropylene sorbitol, polyoxybutylene polyoxyethylene pentaerythritol ether, polyoxyethylene methyl glucoside, polyoxypropylene methyl glucoside, and the like. Examples of the aforementioned fatty acids include saturated fatty acids such as hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, capric acid, lauric acid, myristic acid, palmitic acid, and stearic acid; monounsaturated fatty acids such as crotonic acid, myristoleic acid, palmitoleic acid, sapienic acid, oleic acid, elaidic acid, gadolic acid, and eicosenoic acid; diunsaturated fatty acids such as linoleic acid, eicosadienoic acid, and docosadenoic acid; triunsaturated fatty acids such as linolenic acid, pinolenic acid, eleostearic acid, and eicosatrienoic acid; and tetraunsaturated fatty acids such as stearidonic acid, arachidonic acid, and eicosatetraenoic acid. Furthermore, considering the industrial uniformity required when synthesizing or obtaining higher fatty acid esters, polyhydric alcohols with high symmetry are preferred among polyhydric alcohols. Specifically, polyhydric alcohols with higher symmetry than C2 or C3 symmetry are preferred, more preferably polyhydric alcohols with higher symmetry than C2 or C3 symmetry that do not have stereoisomers, even more preferably polyhydric alcohols with higher symmetry than C2 or C3 symmetry that do not have stereoisomers and all hydroxyl groups are equivalent, and pentaerythritol is particularly preferred.

[0262] As described above, it is preferable that the higher fatty acid ester has two or fewer OH groups (hydroxyl groups) in its molecule. Using a higher fatty acid ester with such a molecular structure helps maintain good dispersion in the resin composition and reduces the likelihood of clouding, which can worsen haze. In addition, it can suppress mold contamination due to bleed-out during molding.

[0263] Furthermore, the aforementioned higher fatty acid ester preferably has a melting point of 0°C or higher, more preferably 10°C or higher, even more preferably 25°C or higher, and particularly preferably 35°C or higher. Being in this temperature range makes relaxation less likely to occur in a room temperature environment, which helps to suppress mold contamination due to bleed-out during molding and a decrease in mechanical strength.

[0264] Furthermore, the melting point of the higher fatty acid ester is preferably 10°C or more lower than the glass transition temperature (Tg) of the resin composition of this embodiment (Tg-10°C or lower), more preferably Tg-20°C, and particularly preferably Tg-30°C or lower. Because the melting point of the aforementioned higher fatty acid ester is in this temperature range, it is less likely to cause shape changes in the molded article in the high-temperature region where the main chain of the resin relaxes, and mold contamination due to bleed-out during molding can be suppressed. Furthermore, while annealing processes at temperatures approximately 40°C lower than the glass transition temperature of the resin composition can suppress deformation of the molded article, the effect of reducing birefringence is usually small. However, by using higher fatty acid esters with melting points within the above temperature range, they can move freely because they are above their melting point at that temperature. This promotes relaxation of the ring skeleton and side chains extending from the resin's main chain, thereby effectively reducing birefringence.

[0265] (Other additives) The cyclic olefin copolymer resin composition according to this embodiment may contain various additives as needed, within a range that does not significantly impair the effects of the present invention. There are no particular limitations on the aforementioned additives, but in addition to the higher fatty acid esters, examples include weather stabilizers, heat stabilizers, antioxidants, light stabilizers such as hindered amine-based light stabilizers, ultraviolet absorbers, mold release agents, lubricants, thermoplastic resins other than cyclic olefin copolymers, metal deactivators, hydrochloric acid absorbers, slip agents, antiblocking agents, antifogging agents, synthetic oils, paraffin, organic polysiloxanes, mineral oils and other softeners, plasticizers, flame retardants, antistatic agents, organic fibers, inorganic fillers such as pigments such as iron oxide, reinforcing materials such as glass fibers, carbon fibers, metal whiskers, colorants, organophosphorus compounds such as phosphites, phosphonites, and phosphate esters, and other additives, or mixtures thereof.

[0266] <Method for producing resin compositions> The method for producing the resin composition is not particularly limited, as long as it can produce a resin composition that satisfies the requirements of the present invention. For example, a method of kneading using a kneader such as an extruder, heated roll, kneader, roller mixer, or Banbury mixer can be used. Among these, kneading with an extruder is preferred in terms of productivity. The kneading temperature should follow the preferred processing temperature of the polymer constituting the methacrylic resin and the other resins being mixed, and as a guideline, it is in the range of 140 to 300°C, preferably in the range of 180 to 280°C. Furthermore, it is preferable to provide a vent in the extruder in order to reduce volatile matter.

[0267] In this embodiment, the resin composition constituting the base material portion of the light guide member preferably has a residual solvent amount of less than 1000 ppm by mass, more preferably less than 800 ppm by mass, and even more preferably less than 700 ppm by mass. Here, the remaining solvent refers to the polymerization solvent used during polymerization (excluding alcohols), and the solvent used to redissolve and hydrate the resin obtained by polymerization. Specifically, examples of polymerization solvents include aromatic hydrocarbons such as toluene, xylene, ethylbenzene, and isopropylbenzene; ketones such as methyl isobutyl ketone, butyl cellosolve, methyl ethyl ketone, and cyclohexanone; polar solvents such as dimethylformamide and 2-methylpyrrolidone; and examples of solvents used for redissolution include toluene, methyl ethyl ketone, and methylene chloride.

[0268] The resin composition preferably has a residual alcohol content of less than 500 ppm by mass, more preferably less than 400 ppm by mass, and even more preferably less than 350 ppm by mass. Here, the remaining alcohol refers to the alcohol produced as a by-product of the cyclization condensation reaction, and specific examples include methanol, ethanol, isopropanol, and other aliphatic alcohols.

[0269] The amount of residual solvent and the amount of residual alcohol can be measured by gas chromatography.

[0270] In any method chosen, it is preferable to prepare the composition while minimizing oxygen and water content as much as possible. For example, in solution polymerization, the dissolved oxygen concentration in the polymerization solution is preferably less than 300 ppm during the polymerization process, and in preparation methods using an extruder, the oxygen concentration in the extruder is preferably less than 1% by volume, and more preferably less than 0.8% by volume. The moisture content of the methacrylic resin is preferably adjusted to 1000 ppm by mass or less, more preferably 500 ppm by mass or less. Within these ranges, it becomes relatively easy and advantageous to prepare compositions that satisfy the requirements of the present invention.

[0271] <Properties of resin compositions> -Glass transition temperature- The glass transition temperature (Tg) of the resin composition is preferably 105°C to 160°C. The glass transition temperature of the resin composition is more preferably 110 to 155°C, still more preferably 115 to 150°C, and most preferably 120 to 150°C. Incidentally, the glass transition temperature can be measured by the midpoint method in accordance with JIS-K7121. When the glass transition temperature of the resin composition is 105°C or higher, heat resistance is ensured even in the heat generated from the electronic devices of the head-mounted display and in high-temperature environments in some outdoor and in-vehicle environments, and the shape is maintained even at high temperatures. Therefore, it is also preferable from the viewpoint of improving the adhesion in the lamination with various optical films. On the other hand, when the glass transition temperature (Tg) is 160°C or lower, extreme high-temperature melt processing can be avoided, thermal decomposition of the resin and the like can be suppressed, and good products can be obtained. The glass transition temperature (Tg) is preferably 155°C or lower, more preferably 150°C or lower, and still more preferably 140°C or lower in terms of further obtaining the above-described effects. Also, when the glass transition temperature exceeds 150°C, in the injection molding process described later, the mold temperature needs to be kept high to reduce the birefringence of the resin light guide member. However, when taking out the light guide member, in order to suppress deformation such as sink marks, it is necessary to take a long cooling time, which increases the cycle time. In addition, due to the temperature difference from room temperature, distortion easily remains in the light guide member due to rapid cooling, which is not preferable from the viewpoint of sufficiently reducing the birefringence of the light guide member.

[0272] - Photoelastic coefficient CR- The resin composition has an absolute value |CR| of the photoelastic coefficient CR of 10.0×10 -12 Pa -1 or less, more preferably 5.0×10 -12 Pa -1 or less, still more preferably 3.0×10 -12 Pa -1 or less, and even more preferably 1.0×10 -12 Pa -1The following is the explanation. The photoelastic coefficient is described in various literatures (for example, see Chemistry Review, No. 39, 1998 (published by Gakkai Shuppan Center)), and is defined by the following equations (ia) and (ib). It can be seen that the closer the value of the photoelastic coefficient CR is to zero, the smaller the change in birefringence due to external force. |CR|=|Δn| / σR ···(ia) |Δn|=|nx-ny| ···(ib) (In the formula, CR represents the photoelastic coefficient, σR represents the tensile stress, |Δn| represents the absolute value of the birefringence, nx represents the refractive index in the direction of extension, and ny represents the refractive index in the direction perpendicular to the direction of extension within the plane.) The absolute value of the photoelastic coefficient CR of the above resin composition is 3.0 × 10⁻⁶. -12 Pa -1 If the following conditions are met, a light guide member can be obtained in which the stress generated when fixing and bonding the lens to the lens barrel or jig, as well as the photoelastic birefringence caused by dimensional and temperature changes, are sufficiently small, resulting in a clear image.

[0273] -Molecular weight and molecular weight distribution- The resin composition has a weight-average molecular weight (Mw) in terms of polymethyl methacrylate, as measured by gel permeation chromatography (GPC), preferably in the range of 80,000 to 170,000, more preferably in the range of 90,000 to 170,000, even more preferably in the range of 100,000 to 150,000, and even more preferably in the range of 110,000 to 150,000. When the weight-average molecular weight (Mw) is within the above range, it also exhibits an excellent balance between mechanical strength and fluidity.

[0274] The weight-average molecular weight (Mw), number-average molecular weight (Mn), and Z-average molecular weight (Mz) of the above resin composition can be measured using the following apparatus and under the following conditions. • Measuring device: Gel permeation chromatography (HLC-8320GPC) manufactured by Tosoh Corporation • Measurement conditions: The columns used are: one TSKguardcolumn SuperH-H, two TSKgel SuperHM-M, and one TSKgel SuperH2500, connected in series in that order. Column temperature: 40℃ Developing solvent: tetrahydrofuran, flow rate: 0.6 mL / min, 2,6-di-t-butyl-4-methylphenol (BHT) is added as an internal standard at a concentration of 0.1 g / L. Detector: RI (Differential Refraction) detector Detection sensitivity: 3.0 mV / min Sample: 0.02 g of light guide material in a 20 mL solution of tetrahydrofuran. Injection volume: 10μL Standard samples for calibration curve: The following 10 polymethyl methacrylates (Polymer Laboratories; PMMA Calibration Kit MM-10) with known monodisperse weight peak molecular weights and different molecular weights will be used. Weight-peak molecular weight (Mp) Standard sample 1: 1,916,000 Standard sample 2 625,500 Standard sample 3: 298,900 Standard sample 4 138,600 Standard sample 5 60,150 Standard sample 6 27,600 Standard sample 7 10,290 Standard sample 8 5,000 Standard sample 9 2,810 Standard sample 10 850 Under the above conditions, the RI detection intensity is measured in relation to the elution time of the light guide member. Based on the calibration curves obtained by measuring the above-mentioned standard samples for calibration, the weight-average molecular weight (Mw), number-average molecular weight (Mn), and Z-average molecular weight (Mz) of the light guide member are determined, and these values ​​are used to determine the molecular weight distribution (Mw / Mn) and (Mz / Mw).

[0275] -Saturated water absorption rate- The resin composition can be measured for its saturated water absorption rate using the measurement method described in the examples below. The saturated water absorption rate is preferably in the range of 0.005% to 3%, more preferably in the range of 0.007% to 2.5%, and even more preferably in the range of 0.01% to 2.0%. By using a resin composition in this range to constitute the base material portion of the light guide member, good adhesion with the anti-reflective coating and mirror coating can be maintained, and high surface accuracy can be maintained even after high temperature and high humidity testing.

[0276] -Melting viscosity- The resin composition preferably has low viscosity and high fluidity in the state equivalent to that at injection to enhance the transferability of the lens shape. Therefore, the melt viscosity is 270°C, 1000 sec. -1 In this regard, the viscosity is preferably 20 to 235 Pa·sec, more preferably 20 to 230 Pa·sec, even more preferably 30 to 180 Pa·sec, and particularly preferably 50 to 150 Pa·sec. If the melt viscosity is less than 20 Pa·sec, it becomes difficult to control the flow of the resin during injection, resulting in poor holding pressure and poor surface accuracy of the lens (deviation from the design value or reference radius of curvature), as well as deterioration of surface accuracy due to sink marks on the lens after molding. On the other hand, if the melt viscosity is greater than 235 Pa·sec, the fluidity of the resin decreases, resulting in poor transferability of the lens shape, making molding extremely difficult, especially for thin-walled lenses. If the resin is forcibly pushed into the mold, the light guide member will stick to the mold, leading to problems such as chipping and cracking during demolding, and discoloration and burnt foreign matter due to burning of the resin during troubleshooting. The melt viscosity is a value measured in accordance with JIS-K7199.

[0277] [Manufacturing method for light guide members] The light guide member of this embodiment is formed by molding the above-mentioned resin composition and bonding various components to it. From the viewpoint of productivity, injection molding or injection compression molding is preferred as the manufacturing method for the light guide member of this embodiment.

[0278] Typically, injection molding consists of (1) an injection step in which resin is melted and the molten resin is filled into the cavity of a temperature-controlled mold; (2) a holding pressure step in which pressure is applied to the cavity until the gate seal is reached, and resin equivalent to the amount of resin lost when the molten resin filled in the injection step comes into contact with the mold and cools and shrinks is injected; (3) a cooling step in which the molded product is held in place after the holding pressure is released until the resin cools; and (4) a step in which the mold is opened and the cooled molded product is removed.

[0279] In this embodiment, the temperature setting from the nozzle tip to the center of the injection molding machine cylinder is preferably in the range of Tg+120 to Tg+180°C, more preferably Tg+100°C to Tg+160°C, and more preferably Tg+110°C to Tg+150°C, based on the glass transition temperature (Tg) of the methacrylic resin composition used. Here, the molding temperature refers to the control temperature of the band heater wrapped around the injection nozzle. By setting the temperature within the above range, molding becomes possible in a state where the molten resin flows sufficiently and degradation due to thermal decomposition of the resin is suppressed. Higher molding temperatures increase the fluidity of the resin and make orientational birefringence less likely to occur. However, at high temperatures, thermal decomposition of the resin negatively affects the color tone, transmittance, and haze. In addition, gas is generated during injection molding, and the generated gas fills the mold. When the resin is filled, the gas that is pushed into the uneven parts cannot be released, hindering resin filling and resulting in a poor mold transfer rate. The molding temperature should be selected appropriately while observing the condition of the light guide member.

[0280] By raising the mold temperature to a temperature near Tg, the birefringence of the light guide member can be reduced. Furthermore, it is preferable to set the actual surface temperature to the desired temperature, rather than the set mold temperature. Specifically, when injection molding the light guide member of this embodiment, it is preferable to set the mold temperature in the range of (Tg-30)°C to (Tg+10)°C with respect to the glass transition temperature (Tg) of the resin composition used. More preferably, it is (Tg-25)°C to (Tg+5)°C, and even more preferably, (Tg-20)°C to (Tg)°C. By setting the mold temperature in the above range, the birefringence of the resin composition can be reduced, and furthermore, warping can be suppressed, and a light guide member with good surface accuracy can be obtained. If the mold temperature is below (Tg-30)°C, the degree of orientation increases, and birefringence tends to increase. In addition, the fluidity of the resin in the mold decreases, so thickness unevenness occurs in the light guide member and surface accuracy tends to deteriorate. On the other hand, if the temperature is higher than (Tg+10)℃, surface accuracy deteriorates due to adhesion to the mold, thermal shrinkage, and warping. Therefore, it is preferable that the mold temperature be within the above range.

[0281] The cooling time during injection molding can be set as needed, but it is generally better to make it as long as possible. Slow cooling tends to reduce birefringence because the distortion caused by molding is alleviated by the annealing effect. In the manufacturing of the light guide member of this embodiment, an annealing process may be performed to alleviate residual stress generated by injection molding and reduce birefringence of the light guide. The temperature during annealing is preferably in the range of (Tg-50)°C to (Tg)°C, more preferably (Tg-40)°C to (Tg-5)°C, and even more preferably in the range of (Tg-30)°C to (Tg-10)°C, based on the glass transition temperature (Tg) of the resin composition. If the annealing temperature is within the above range, residual stress can be removed without deformation of the light guide. Alternatively, after annealing at a high temperature once, slow cooling to a low temperature of about Tg-50°C may be performed, followed by additional annealing. Some resin compositions exhibit strong birefringence due to internal strain generated when rapidly cooled from a high temperature. Furthermore, for annealing in the temperature range of about Tg-50°C, the photoelastic coefficient is 3 × 10⁻⁶. -12 Pa -1Furthermore, this method is particularly effective for resin compositions in which a large amount of plasticizer is added (0.5 parts by mass or more per 100 parts by mass of resin), as the plasticizer moves within the same temperature range, promoting the relaxation of internal strain in the resin and reducing birefringence. Furthermore, for resin compositions in which a large amount of plasticizer is added (0.5 parts by mass or more per 100 parts by mass of resin), annealing at a temperature near the melting point of the plasticizer, approximately (Tg-50)°C to (Tg-20)°C, is also effective. In this case, as mentioned above, the plasticizer acts in a way that promotes the relaxation of internal strain in the resin at this temperature range, suppressing changes in surface shape at high temperatures while enabling a reduction in birefringence due to annealing.

[0282] Furthermore, the injection speed can be appropriately selected depending on the thickness and dimensions of the light guide member to be obtained, but for example, it can be appropriately selected from the range of 2 to 1000 mm / second. When the thinnest part has a thickness of about 1 mm, it is preferable to set the injection speed to be fast in order to complete the injection before the skin layer is formed, and when the thinnest part has a thickness of 4 mm or more, it is preferable to set the injection speed to 1 to 20 mm / second. In addition, in order to suppress abrupt changes in the flow rate of the resin composition into the mold at thin-walled parts such as the gate of the mold, it is preferable to appropriately change the injection speed when passing through the gate and thereafter. Furthermore, the pressure for holding pressure can be appropriately selected depending on the desired shape of the light guide member, but for example, it can be appropriately selected within the range of 30 to 120 MPa. Here, the pressure for holding pressure is the pressure held by the screw that further delivers molten resin from the gate after the molten resin has been filled.

[0283] When molding light guide members by injection molding, even when the molded body has cooled to room temperature, if the contact temperature of each surface is not uniform, the surface shape of the molded body changes due to the temperature difference, resulting in anisotropic changes. In particular, when the surface shape is complex, the residual stress from molding relaxes over time, causing dimensional changes with strong anisotropy, making it difficult to obtain a light guide member that can guide images without distortion. Therefore, after injection molding and removing the light guide member from the mold, it is preferable to keep each surface involved in the optical design from contact with metal or other heat-conductive objects for a certain period of time, for example, one day. Specifically, by keeping the optically effective surface exposed to air for one day, such as by not cutting the gate and holding the runner and sprue, inserting and holding the sprue in a test tube rack, or taping the sprue to a tray, the temperature distribution of each surface becomes uniform, making it less likely for the surface shape to change even after several days have passed since molding, and enabling the production of a molded product with good surface accuracy.

[0284] [Head-mounted display] The head-mounted display of this embodiment is characterized by comprising the light guide member of this embodiment. The light guide member of this embodiment can provide images while suppressing defects such as brightness unevenness, color unevenness, and rainbow appearance. Therefore, a head-mounted display equipped with this light guide member can provide images while suppressing defects such as brightness unevenness, color unevenness, and rainbow appearance.

[0285] In this embodiment, the head-mounted display preferably has, at least one of the optical output section and the eye-side waveguide section, a reflectance of S-polarized light at an incident angle of 30° greater than the reflectance of P-polarized light, and a difference of 5% or more between the reflectance of S-polarized light and P-polarized light. More preferably, the difference between the reflectance of S-polarized light and P-polarized light at an incident angle of 30° is 10% or more, and more preferably 15% or more.

[0286] In the head-mounted display of this embodiment, it is preferable that partial mirrors are formed on part or all of both sides of the waveguide portion of the two surfaces of the light guide member, which transmit a portion of the light and reflect the remaining portion. Furthermore, the partial mirrors may be formed on part or all of one of the two waveguide portions, or on all of the waveguide portions of both surfaces.

[0287] In the head-mounted display of this embodiment, it is preferable to guide the light at an incident angle larger than that of the substrate portion, and if sufficient light utilization efficiency can be ensured, it is preferable to guide the light at an incident angle smaller than the critical angle of the substrate portion of the light guide member.

[0288] In the head-mounted display of this embodiment, as shown in Figure 6, it is preferable to have a linear polarizing plate on a straight line extending outwards from the observer's eyeball to the output coupler of the light guide member. A head-mounted display with such a configuration functions as polarized sunglasses. Furthermore, in a head-mounted display with the above configuration, the head-mounted display may have, in addition to a linear polarizer, a half-wavelength element or a phase difference layer that imparts a half-wavelength phase difference. Preferably, as shown in Figure 7, the head-mounted display has a linear polarizer and a half-wavelength plate or a phase difference layer that imparts a half-wavelength phase difference, in order from the outside, on a straight line extending from the outside to the outside, connecting the observer's eyeball to the output coupler of the light guide member. By adjusting the reflectivity characteristics of the partial mirror and using a partial mirror with high polarization reflectivity for S-polarized light relative to the waveguide for the output coupler and the outside-side waveguide, and by using an image display element that emits S-polarized light (relative to the waveguide), it is possible to design a configuration that exhibits high transmittance to light incident from the outside, while exhibiting high reflectivity to the image light guided within the light guide member.

[0289] The head-mounted display of this embodiment can be manufactured using the light guide member of this embodiment by a known method. [Examples]

[0290] The present invention will be described below with reference to specific examples and comparative examples, but it is not limited to these.

[0291] (Evaluation of resin composition and light guide member) The following describes the measurement methods for the properties of the resin composition and the light guide member composed of the resin composition.

[0292] <Measurement of flexural strength and flexural modulus> The resin composition pellets produced in the synthesis examples described later were dried at 80-100°C for 24 hours. For the methacrylic resin composition, a 4.0 mm thick ISO 3167 Type A dumbbell test specimen was prepared by injection molding using an injection molding machine (Toshiba Machine Co., Ltd., EX-100SX) in accordance with JIS-K6717. For the cyclic olefin copolymer resin composition, a 4.0 mm thick ISO 3167 Type A dumbbell test specimen was prepared by injection molding using an injection molding machine (Japan Steel Works Ltd., J100ADS-110U) in accordance with JIS-K7152-1. A molded piece measuring 80 mm in length, 10 mm in width, and 4.0 mm in thickness was prepared by cutting out the central portion of this test specimen. A bending test was performed using a low-load universal material testing machine (manufactured by Instron) in accordance with ISO 178, at a measurement temperature of 23°C, a test speed of 2 mm / min, and a support distance of 64 mm. Six measurements were taken, and the bending strength (MPa) was calculated as the average value.

[0293] <Analysis of structural units> In the light guide members manufactured in the examples and comparative examples described below, each structural unit of the substrate portion that has been shredded is, unless otherwise specified. 1 H-NMR measurement and 13 By using 1C-NMR measurements, each structural unit of the resin composition was identified, and its abundance was calculated. 1 H-NMR measurement and 13 The measurement conditions for 1C-NMR are as follows: • Measuring instrument: JEOL Ltd. JNM-ECZ400S • Measurement solvent: CDCl3 or d6-DMSO ·Measurement temperature: 40℃ Furthermore, if the ring structure contained in the main chain of the methacrylic resin is a lactone ring structure, this was confirmed by the method described in Japanese Patent Publication No. 2001-151814 and Japanese Patent Publication No. 2007-297620.

[0294] <Identification of the ring structure ratio of cyclic olefin copolymers> In the light guide members manufactured in the examples and comparative examples described below, each structural unit of the substrate portion that has been shredded is: 13 By using 1C-NMR measurements, each structural unit of the resin composition was identified, and its abundance was calculated. First, 5.0 grams of the cyclic olefin resin composition was dissolved in 50 mL of cyclohexane, then reprecipitation was performed by adding 300 mL of methanol, and the methanol-insoluble portion was separated by filtration. The solvent was evaporated, and the solid content was separated. The solid content was quantified so that the sample concentration was 5.0 wt / vol%, and 1.0 mL of o-dichlorobenzene-d4 was added. The sample was left at room temperature for 16 hours or more to completely dissolve it. 13 1C-NMR measurements were performed. For quantification, the ratio of CH to CH2 is calculated from the ratio of the sum of the integral values ​​k of all peaks observed in the range of 51.2 ppm to 36.8 ppm and the sum of the integral values ​​l of all peaks observed in the range of 36.8 ppm to 29.3 ppm, respectively. Using the following formula (i), a predetermined amount of olefin and cyclotetracyclo[4.4.0.12,5.17,10]-3-dodecene are found to be in a molar ratio of n% for olefin and ((100-n)%) for cyclotetracyclo[4.4.0.1 2,5 .1 7,10 We confirmed that ]-3-dodecene was copolymerized. n(%)=(4×l-2×k) / (4×lk)×100 ···(i) In addition, 13 The measurement conditions for 1C-NMR are as follows: • Measuring instrument: Bruker Biospin AVANCE3 500HD Prodigy • Solvent used for measurement: o-dichlorobenzene-d4 ·Measurement temperature: 25℃ Observation frequency: 125MHz • Pulse sequence: 13 C quantitative • Total number of times: 700 • Relaxation time: 10 seconds • Sample concentration: 5.0 wt / vol%

[0295] <Measurement of plasticizer content in resin compositions> The amount of additives in the light guide members manufactured in the examples and comparative examples described below was analyzed by the following procedure. First, the base material portion of the light guide member was cut out, and 5.0 g of the resin composition constituting the base material was added to 100 mL of chloroform (50 mL of cyclohexane in the case of cyclic olefin copolymer) and stirred at 40°C for more than 1 hour to dissolve. Then, the solution was placed in a dropping funnel and added dropwise over approximately 0.5 to 1 hour to 1 L of methanol being stirred with a stirring bar to reprecipitation. After the entire volume had been added, it was allowed to stand for 1 hour, and then suction filtration was performed using a membrane filter (T05A090C, manufactured by Advantec Toyo Co., Ltd.) as the filter. The filtrate was removed using a rotary evaporator with a bath temperature of 40°C and the vacuum gradually reduced from the initial setting of 390 Torr to a final vacuum of 30 Torr. After removing the solvent, the soluble matter remaining in the round-bottom flask was collected and identified as methanol-soluble matter. The solid content was weighed to achieve a sample concentration of 5.0 wt / vol%, 1.0 mL of CDCl3 was added, and the sample was allowed to dissolve completely at room temperature for at least 30 minutes. 1000 ppm of DMSO was added as an internal standard (with a weight of (w) mg). 1 1H-NMR measurements were performed. For the final volume, the integral value for 6H of DMSO alone (ab) was obtained by subtracting the same value (b) as the integral value from components such as pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]: BASF's "Irganox 1010" and tris(2,4-di-t-butylphenyl) phosphite: BASF's "Irgafos 168", which is observed at 2.79-2.88 ppm, from the integral value (a) derived from DMSO at 2.56-2.65 ppm. Furthermore, the percentage content (x) of each compound was quantified using the following equation (ii) by utilizing the integral value (y) of the peak observed within the following chemical shift range, the molecular weight (M) of the additive, and the number of equivalent proton peaks (z). x(%)=(w / 78.1×y / (ab)×6 / z×M) / 5000×100···(ii) In particular, for additives containing higher fatty acid esters, the integral value of the α-hydrogen-derived peak in the higher fatty acid portion observed at 2.0–2.5 ppm was quantified using equation (II) with y, molecular weight M, and the number of equivalent α-hydrogen-derived hydrogens z. The integration range, M, and z for the additives applicable to the examples are shown below. Pentaerythritol distearate Integration range: 2.27 ppm to 2.38 ppm M=669.09 z=4 Pentaerythritol tetrastearate Integration range: 2.27 ppm to 2.38 ppm M=1201.99 z=8 In addition, 1 The measurement conditions for H-NMR are as follows: • Measuring instrument: Bruker Biospin AVANCE3 500HD Prodigy • Measurement solvent: CDCl3 ·Measurement temperature: 25℃ Observation frequency: 500MHz • Total number of times: 128 • Sample concentration: 5.0 wt / vol%

[0296] <Molecular weight and molecular weight distribution (1)> The weight-average molecular weight (Mw), number-average molecular weight (Mn), and Z-average molecular weight (Mz) of the light guide members excised from the light guide members produced in the examples and comparative examples described below were measured using the following apparatus and conditions. In cases where the light guide members were produced using a resin composition containing a cyclic olefin copolymer, which is a copolymer of ethylene or α-olefin and a cyclic olefin, with the ring structure in the main chain consisting of a cyclic olefin, the measurements were performed under the conditions described in <Molecular Weight and Molecular Weight Distribution (2)> below. • Measuring device: Gel permeation chromatography (HLC-8320GPC) manufactured by Tosoh Corporation • Measurement conditions: The following columns were used, connected in series: one TSKguardcolumn SuperH-H, two TSKgel SuperHM-M, and one TSKgel SuperH2500. Column temperature: 40℃ The developing solvent was tetrahydrofuran, the flow rate was 0.6 mL / min, and 2,6-di-t-butyl-4-methylphenol (BHT) was added as an internal standard at a concentration of 0.1 g / L. Detector: RI (Differential Refraction) detector Detection sensitivity: 3.0 mV / min Sample: 0.02 g of methacrylic resin composition in a 20 mL solution of tetrahydrofuran. Injection volume: 10μL Standard samples for the calibration curve: The following 10 polymethyl methacrylates (Polymer Laboratories; PMMA Calibration Kit MM-10) with known monodisperse weight peak molecular weights and different molecular weights were used. Weight-peak molecular weight (Mp) Standard sample 1: 1,916,000 Standard sample 2 625,500 Standard sample 3: 298,900 Standard sample 4 138,600 Standard sample 5 60,150 Standard sample 6 27,600 Standard sample 7 10,290 Standard sample 8 5,000 Standard sample 9 2,810 Standard sample 10 850 Under the above conditions, the RI detection intensity was measured as a function of the elution time of the methacrylic resin composition. Based on the calibration curves obtained by measuring the above-mentioned standard samples, the weight-average molecular weight (Mw), number-average molecular weight (Mn), and Z-average molecular weight (Mz) of the methacrylic resin composition were determined, and the molecular weight distribution (Mw / Mn) and (Mz / Mw) were determined using these values.

[0297] <Molecular weight and molecular weight distribution (2)> In the light guide members produced in the examples and comparative examples described below, if the resin composition used is a resin composition in which the ring structure contained in the main chain consists of a cyclic olefin and includes a cyclic olefin copolymer which is a copolymer of ethylene or α-olefin and a cyclic olefin, the weight-average molecular weight (Mw), number-average molecular weight (Mn), and Z-average molecular weight (Mz) of the portion of the light guide member that was cut out were measured using the following apparatus and conditions. • Measuring device: Agilent (PL-GPC220) • Measurement conditions: Two TSKguardcolumn GMHHR-H(20)HT columns (7.8mm I.D. × 30cm) were used, connected in series. Column temperature: 145℃ Developing solvent: o-dichlorobenzene. However, it contains 0.05% 2,6-di-t-butyl-4-methylphenol (BHT). Detector: RI (Differential Refraction) detector Detection sensitivity: 3.0 mV / min Sample: The sample was weighed into a high-temperature filter to achieve a solution concentration of 1 mg / mL, 5 mL of eluent was added, and the mixture was heated at 145°C for 30 minutes and then shaken for 1 hour to dissolve. Injection volume: 500μL Flow rate: 0.7mL / min Standard samples for calibration curve: The following 10 types of polystyrene with different molecular weights and known monodisperse weight peak molecular weights were used. Weight-peak molecular weight (Mw) Standard sample 1: 6,570,000 Standard sample 2: 2,703,000 Standard sample 3: 729,500 Standard sample 4 301,600 Standard sample 5 133,500 Standard sample 6 70,500 Standard sample 7 27,810 Standard sample 8 9,570 Standard sample 9 3,090 Standard sample 10 580 Under the above conditions, the RI detection intensity was measured in relation to the elution time of the resin lens. Based on the calibration curves obtained from the measurements of the standard samples used for calibration, the weight-average molecular weight (Mw), number-average molecular weight (Mn), and Z-average molecular weight (Mz) of the resin were determined, and the molecular weight distributions (Mw / Mn) and (Mz / Mw) were determined using these values.

[0298] <Measurement of glass transition temperature> The glass transition temperature (Tg) (°C) was measured in accordance with JIS-K7121. First, after conditioning the light guide members produced in the examples and comparative examples described below under standard conditions (23°C, 50%RH) (leaving them at 23°C for one week), four test pieces (approximately 10 mg each) were cut from the light guide member portion. Next, a differential scanning calorimeter (Diamond DSC, manufactured by PerkinElmer Japan Co., Ltd.) was used under nitrogen gas flow rate of 25 mL / min. Here, the temperature was increased from room temperature (23°C) to 200°C at 10°C / min (primary heating), held at 200°C for 5 minutes to completely melt the sample, then cooled from 200°C to 40°C at 10°C / min, held at 40°C for 5 minutes, and then heated again under the same heating conditions (secondary heating). The intersection point of the stepped change portion of the DSC curve drawn during the secondary heating and the straight line equidistant in the vertical direction from each baseline extension line was measured (the glass transition temperature of the methacrylic resin composition was measured in accordance with JIS-K7121). A differential scanning calorimeter (DSC8000, manufactured by PerkinElmer Japan Co., Ltd.) was used under nitrogen gas flow rate of 25 mL / min. The sample was heated from room temperature (23°C) to 200°C at a rate of 10°C / min (primary heating), held at 200°C for 5 minutes to completely melt the sample, then cooled from 200°C to 40°C at a rate of 10°C / min, held at 40°C for 5 minutes, and then heated again under the same heating conditions (secondary heating). The glass transition temperature (Tg) (°C) was measured at the intersection point (midpoint glass transition temperature) of the DSC curve drawn during the step-like change portion of the curve during the secondary heating and a straight line equidistant in the vertical direction from each baseline extension. Four measurements were taken per sample, and the arithmetic mean of the four points (rounded to the nearest whole number) was used as the measured value.

[0299] <Measurement of the absolute value of the photoelastic coefficient (CR)> Of the light guide members manufactured in the examples and comparative examples described later, the base material portion of the light guide member was shredded and pressed into a film using a vacuum compression molding machine to prepare a sample for measurement. The specific sample preparation conditions involved using a vacuum compression molding machine (SFV-30 model, manufactured by Shinto Metal Industries Co., Ltd.) to preheat the machine at 260°C under reduced pressure (approximately 10 kPa) for 10 minutes. After cutting the material from the light guide member, it was compressed at 260°C at approximately 10 MPa for 5 minutes. After releasing the reduced pressure and press pressure, it was transferred to a cooling compression molding machine for cooling and solidification. The resulting pressed film was cured for more than 24 hours in a constant temperature and humidity chamber adjusted to 23°C and 60% humidity, after which a test piece for measurement (approximately 150 μm thick, 6 mm wide) was cut out. Using a birefringence measuring device described in detail in Polymer Engineering and Science 1999, 39, 2349-2357, the photoelastic coefficient CR (Pa) was measured. -1 ) was measured. A film-like test specimen was placed in a film tensile device (manufactured by Imoto Seisakusho) installed in a temperature and humidity-controlled chamber, with a chuck spacing of 50 mm. Next, the birefringence measuring device (manufactured by Otsuka Denshi, RETS-100) was positioned so that the laser beam path was located at the center of the film, and the birefringence of the test specimen was measured while applying tensile stress at a strain rate of 50% / min (chuck spacing: 50 mm, chuck movement speed: 5 mm / min). From the relationship between the birefringence (Δn) and tensile stress (σR) obtained by measurement, the slope of the line is determined by least squares approximation, and the photoelastic coefficient (CR) (Pa) is calculated. -1 The calculation was performed using data where the tensile stress was between 2.5 MPa and σR (10 MPa). CR = Δn / σR Here, the birefringence (Δn) is the value shown below. Δn = nx - ny (nx: refractive index in the stretching direction, ny: refractive index in the direction perpendicular to the stretching direction in the plane)

[0300] <Phase difference within the effective area of ​​the light guide member> The light guide members obtained in the examples and comparative examples were subjected to a birefringence evaluation system PA-300-L manufactured by Photonic Lattice Co., Ltd., with one of the two surfaces constituting the waveguide portion facing downwards. The surface distribution of the phase difference within the effective area was measured at a wavelength of 520 nm, and the average value (nm) of the absolute value of the phase difference was determined by specifying a region within the effective area.

[0301] <Measurement of surface accuracy PV value of light guide material> A non-contact three-dimensional measuring machine NH-3SPs (manufactured by Mitaka Kohki Co., Ltd.) was used, and the surface to be measured was positioned with a fixing jig so that the surface to be measured faced the objective lens side of the NH-3SPs, and the surface accuracy was measured. A 100x magnification objective lens was used. If the shape of the light guide member had a protrusion that interfered with the objective lens and made shape measurement difficult, the protrusion was either removed before measurement or a rotating stage was used. In the configuration shown in Figure 8, measurements were taken in the x-axis and z-axis directions, with the light guide folded back at a length of 1 / 50 of the z-axis length (short side) from the outer circumference. PV values ​​were measured on all surfaces involved in guiding the image light, and the value of the surface with the highest PV value was taken as the PV value of the light guide. During measurement, the measurement pitch m in the x-axis direction is 1 / 1 of the longest part of the length of the light guide in the x-axis direction. Set to 000, the measurement pitch in the z direction is 1 / 1 of the longest part of the z-axis length of the light guide. The setting was set to 0, and measurements were taken. If the light guide surface had a diffracting portion, the PV value was determined by measuring the surface excluding that portion. A smaller PV value indicates higher flatness of the light guide, suppression of warping and thickness unevenness, resulting in a better appearance and superior image quality. Furthermore, if the area of ​​the light guide is large, for example, if its length in the z-axis direction is 50 mm and it falls outside the operating range in the z-axis direction of the stage, the measurement range is divided into equal sections of 25 mm in the z-axis direction, and measurements are performed in each section. The average of the measurement results from each section is taken as the PV value.

[0302] <Polarization reflectivity characteristics of partial mirrors in light guide components> The polarization reflectance of the partial mirrors formed on the light guide members obtained in the examples and comparative examples was measured using a Shimadzu UV-2600 spectrophotometer equipped with a large sample chamber, a variable incidence angle device, a light guide member mounting axis, and a large polarizer assembly. A 5mm rectangular aperture mask was used for the incident light, and the angle of incidence was adjusted to be between 15 and 60 degrees relative to the partial mirror surface. An angle-adjustable integrating sphere was positioned at the angle where the reflected light entered, and the reflectance was measured. To prevent reflected light from other surfaces of the sample from interfering, the surfaces other than the measurement surface were sanded with sandpaper, painted black, and then measured. Figure 9 shows an example of measurement results for a partial mirror coated with a reflectivity set to 35%. It can be seen that the reflectivity of polarization differs depending on the angle of incidence at each wavelength: blue (450nm), green (530nm), and red (630nm). At an incident angle of 30 degrees, the reflectance showed a difference of approximately 17% between Rs and Rp, and the Rs / Rp ratio was 1.8.

[0303] <Polarization retention characteristics (Tp / Tc) of the light guide material> The polarization retention characteristics (Tp / Tc) of the light guide members obtained in the examples and comparative examples were measured by arranging each member in the positional relationship shown in Figure 10A or Figure 10B. A Grant-Thomson prism type polarizing element 72 (a polarizing element that transmits linearly polarized light with a specific vibration and does not transmit linearly polarized light vibrating on an axis perpendicular to the vibration axis of the said linearly polarized light) is placed perpendicular to the axis of the light ray of the laser light source 71 (a blue, green, or red laser light source is used depending on the measurement wavelength; hereinafter, these may be abbreviated as blue LD, green LD, and red LD). The laser light is then incident into the light guide member 733 by positioning the laser light source 71 so as to be incident from a direction perpendicular to the light incident part 731 of the light guide member. After the laser light is guided through the external-side waveguide part 732 and the eye-side waveguide part 733 of the light guide member, the light extracted by the output coupler 734 is directed to the linearly polarizing plate 74 (manufactured by Sigma Koki Co., Ltd., SPF-50C-32, extinction ratio of 10 at 500 nm). 4The optical output was measured using a power meter 75 positioned via the above configuration. When the linear polarizer 72 is positioned so that the incident polarization is S-polarized light with an oscillation axis perpendicular to the incident plane in the waveguide portion of the light guide, the optical output when the transmission axis of the linear polarizer 74 is also positioned to transmit the same S-polarized light is defined as Tp, and the optical output when the linear polarizer 74 is rotated 90 degrees to transmit P-polarized light is defined as Tc, and the polarization retention characteristic of S-polarized light (Tp / Tc) is determined. Then, in order to evaluate the effect of the difference between the reflectance of S-polarized light and P-polarized light at an incident angle of 30° of the partial mirror, the measured value was obtained by dividing the obtained polarization retention characteristic of S-polarized light (Tp / Tc) by the ratio of polarization reflectance (Rs / Rp). If there are multiple reflectance designs for the partial mirror, the measured value was obtained by dividing (Tp / Tc) by the value with the largest ratio of polarization reflectance (Rs / Rp). Similarly, when the linear polarizer 72 is positioned so that the incident polarization is P-polarized light with an oscillation axis parallel to the incident plane in the waveguide portion of the light guide, the optical output when the transmission axis of the linear polarizer 74 is also positioned to transmit the same P-polarized light is defined as Tp, and the optical output when the linear polarizer 74 is rotated 90 degrees to transmit S-polarized light is defined as Tc, and the polarization retention characteristic of P-polarized light (Tp / Tc) is determined. Then, in order to evaluate the value while excluding the effect of the difference in reflectance between S-polarized light and P-polarized light at an incident angle of 30° of the partial mirror, the measured value was obtained by multiplying the obtained polarization retention characteristic of S-polarized light (Tp / Tc) by the ratio of polarization reflectance (Rs / Rp). If there are multiple reflectance designs for the partial mirror, the measured value was obtained by multiplying the above (Tp / Tc) by the value with the largest ratio of polarization reflectance (Rs / Rp). Measurements were performed using lasers of blue, green, and red wavelengths.

[0304] <Light extraction efficiency of light guide components> The light utilization efficiency of the light guide members obtained in the examples and comparative examples was measured in the positional relationship shown in Figure 10A or Figure 10B, where the polarization retention characteristics (Tp / Tc) described above were measured. First, in the configuration shown in Figure 10A or Figure 10B, a laser light source 71 emitting green light and a power meter 75 were placed at the end of the beam from the Glenthomson prism-type polarizing element 72, and just before it entered the light guide member, to measure the light output T0. Subsequently, the components were arranged in the same positional relationship as shown in Figure 10A or Figure 10B, similar to the measurement of the polarization retention characteristics (Tp / Tc) described above. Light from a green laser light source was incident on the waveguide component, and the light intensity of the laser light emitted from the light extraction section was measured using a power meter 75 via a linear polarizer 74. The optical extraction efficiency was measured from the ratio of the optical output Tp measured at the optical extraction section to the initial optical output T0 incident on the waveguide member. The S-polarized Tp / T0 was measured under the condition that S-polarized light was incident on the reflective surface of the waveguide, and the P-polarized Tp / T0 was measured under the condition that P-polarized light was incident on the reflective surface of the waveguide.

[0305] <Evaluation of Observed Images> The images were evaluated using the light guide members obtained in the examples and comparative examples. As shown in Figure 11, a simulated device based on the principle of an AR head-mounted display was fabricated in a darkroom. In this simulated device, a micro OLED panel 111 (Seeya, SY103WAM13-00) was placed to output an image. The image displayed was a white screen. Image light was introduced into the light guide member 115 from the light incidence section 1151 via an aperture mask 112, a collimating optical system 113, and a linear polarizing plate 114. Next, after guiding the wave guide section, the image light output from the light guide member via the light output section using an output coupler was captured by an imaging camera. The captured images were evaluated under Condition 1, based on the following criteria, in terms of brightness uniformity, color uniformity, and the appearance of rainbows. • No unevenness in brightness, unevenness in color, or rainbows are observed: A • Slight brightness unevenness is observed: B • Brightness and color unevenness are observed: C • Brightness unevenness, color unevenness, and rainbow appearance are observed: D Next, the captured images were examined for distortion according to the following criteria as Condition 2. • No distortion is observed in the image: A • Slight distortion of the image is visible: B • Image distortion is visible: C • Strong image distortion is observed: D

[0306] [Raw materials] The raw materials used in the examples and comparative examples described later are shown below.

[0307] [[Monomers that make up methacrylic resins]] • Methyl methacrylate (MMA): Manufactured by Asahi Kasei Corporation • N-phenylmaleimide (PMI): Manufactured by Nippon Shokubai Co., Ltd. • N-cyclohexylmaleimide (CMI): Manufactured by Nippon Shokubai Co., Ltd. • Styrene: Manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. • α-methylstyrene: Manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. • Methyl 2-(hydroxymethyl)acrylate (MHMA): Manufactured by Combi-Blocks.

[0308] [[organic solvent]] • Metaxylene (mXy): Manufactured by Mitsubishi Gas Chemical Company, Ltd. • Methyl isobutyrate: Manufactured by Kanto Chemical Co., Ltd. • Toluene: Manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

[0309] [[polymerization initiator]] • 1,1-di(t-butylperoxy)cyclohexane: Manufactured by NOF Corporation • t-Amyl peroxy-2-ethylhexanoate: Luperox 575, manufactured by Arkema Yoshitomi Co., Ltd. t-Amil peroxyisononanoate: Manufactured by Arkema Yoshitomi Co., Ltd.

[0310] [[Chain Transfer Agent]] n-Octyl mercaptan: Manufactured by Chevron Philips Chemicals. n-dodecyl mercaptan: Manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

[0311] [[additives]] • Pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]: BASF "Irganox 1010" • Tris(2,4-di-t-butylphenyl) phosphite: BASF "Irgafos168" • Rikemar H-100: Manufactured by Riken Vitamin Co., Ltd. • ADEKA Stub 2112: Manufactured by ADEKA Corporation • Stearyl phosphate / distearyl phosphate mixture: Manufactured by Sakai Chemical Industry Co., Ltd. • ADEKA Stub PEP-36: Manufactured by ADEKA Corporation Octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate: BASF "Irganox 1076" • Monomethylamine: Manufactured by Mitsubishi Gas Chemical Company, Inc. • Dimethyl carbonate: Manufactured by Fujifilm Wako Pure Chemical Corporation Triethylamine: Manufactured by Fujifilm Wako Pure Chemical Corporation • Pentaerythritol distearate: "Unistar H-476D" manufactured by NOF Corporation • Pentaerythritol tetrastearate: "Unistar H-476" manufactured by NOF Corporation

[0312] (Synthesis Example 1 [Methacrylic Resin Composition A]) 318.7 kg of methyl methacrylate (hereinafter referred to as MMA), 35.5 g of N-phenylmaleimide (hereinafter referred to as PMI), 63.7 kg of N-cyclohexylmaleimide (hereinafter referred to as CMI), 0.341 kg of n-octyl mercaptan (a chain transfer agent), and 225.1 kg of metaxylene (hereinafter referred to as mXy) ​​were weighed out and heated in a 1.25 m² tank equipped with a jacketed temperature control device and stirring blades. 3 The mixture was added to the reactor and stirred to obtain a mixed monomer solution. Next, 116.9 kg of mXy was weighed and added to tank 1 to prepare the additional solvent. Furthermore, 104.5 kg of MMA and 85.5 kg of mXy were weighed into tank 2 and stirred to obtain an additional MMA solution. The contents of the reactor were bubbling with nitrogen at a rate of 30 L / min for 1 hour, and dissolved oxygen was removed from both Tank 1 and Tank 2 by bubbling with nitrogen at a rate of 10 L / min for 30 minutes. Subsequently, steam was blown into the jacket to raise the solution temperature in the reactor to 125°C, and polymerization was started by adding a polymerization initiator solution (0.457 kg of 1,1-di(t-butylperoxy)cyclohexane dissolved in 2.67 kg of mXy) ​​at a rate of 1 kg / hour while stirring at 50 rpm. During polymerization, the solution temperature in the reactor was controlled to 125 ± 2°C by temperature regulation using the jacket. Thirty minutes after the start of polymerization, the rate of addition of the polymerization initiator solution was reduced to 0.25 kg / hour, and mXy was further added from tank 1 at a rate of 29.24 kg / hour for 3.5 hours. Next, four hours after the start of polymerization, the addition rate of the polymerization initiator solution was increased to 0.75 kg / hour, and the additional MMA solution was added from tank 2 at a rate of 95 kg / hour for two hours. Furthermore, six hours after the start of polymerization, the rate of addition of the polymerization initiator solution was reduced to 0.25 kg / hour, and the addition was stopped seven hours after the start of polymerization. Eight hours after the start of polymerization, a polymerization solution containing a methacrylic resin was obtained. To this solution, 0.261 kg of Irganox 1010 and 0.784 kg of Irgafos 168 were added as antioxidants, and 0.784 kg of Rikemar H-100 was added as a release agent. Next, the obtained polymerization solution was supplied to a concentration apparatus consisting of a tubular heat exchanger and a vaporization tank, which had been preheated to 250°C, for defoliation. The vacuum level in the vaporization tank was set to 10-15 Torr. The resin flowing down the vaporization tank was discharged with a screw pump, extruded from a strand die, and after water cooling, was pelletized to obtain pellets of methacrylic resin composition A having N-substituted maleimide structural units. The obtained pellets had a glass transition temperature (Tg) of 133°C and a flexural strength of 66 MPa. Other properties are summarized in the table. 1The oxygen weight percentage, determined from the monomer composition ratio obtained from the 1H-NMR composition, was 29% by weight.

[0313] (Synthesis Example 2 [Methacrylic Resin Composition B]) A monomer composition consisting of 75.000 mol% MMA, 24.998 mol% styrene, and 0.002 mol% t-amyl peroxy-2-ethylhexanoate as a polymerization initiator was continuously supplied at 1 kg / h to a 10 L complete mixing tank equipped with helical ribbon blades, and continuous polymerization was carried out at an average residence time of 2.5 hours and a polymerization temperature of 150°C. The liquid was continuously withdrawn from the bottom of the polymerization tank to maintain a constant liquid level and supplied to a concentration device consisting of a tubular heat exchanger and a vaporization tank for defoliation. The vacuum level in the vaporization tank was set to 10-15 Torr. The resin flowing down the vaporization tank was discharged with a screw pump, extruded from a strand die, water-cooled, pelletized, and introduced into a solvent removal device to obtain pelletized methyl methacrylate-styrene copolymer. This copolymer was dissolved in methyl isobutyrate to prepare a 10% by mass methyl isobutyrate solution. 500 parts by mass of this copolymer 10% by mass methyl isobutyrate solution and 1 part by mass of 10% by mass Pd / C (manufactured by NE Chemcat) as a hydrogenation catalyst were charged into a 1000 mL autoclave. The mixture was maintained at a hydrogen pressure of 9 MPa and 200°C for 15 hours to hydrogenate the aromatic double bonds of the styrene moiety of the copolymer. The hydrogenation catalyst was removed by filtration, and 0.04 parts by mass of Rikemar H-100 was added and mixed to the polymer solution. The solution was then supplied to a concentration apparatus consisting of a tubular heat exchanger and a vaporization tank for defoliation. The vacuum level in the vaporization tank was set to 10-15 Torr. The resin flowing down the vaporization tank was discharged with a gear pump, extruded from a strand die, water-cooled, and pelletized to obtain pellets of methacrylic resin composition B. The obtained pellets had a glass transition temperature (Tg) of 119°C and a flexural strength of 95 MPa. Other properties are summarized in the table. 1 The oxygen weight percentage, determined from the monomer composition ratio obtained from the 1H-NMR composition, was 24% by weight.

[0314] (Synthesis Example 3 [Methacrylic Resin Composition C]) In a 30L reaction vessel equipped with a paddle blade agitator, temperature sensor, cooling tube, and nitrogen inlet tube, 2.25 kg of methyl methacrylate, 0.32 kg of methyl 2-(hydroxymethyl)acrylate, 0.024 kg of styrene, and as a chain transfer agent, 0.025 parts by mass of n-dodecyl mercaptan, 0.025 parts of Adekastab 2112, and 5.39 kg of toluene were charged per 100 parts by mass of the total monomers to be charged into the reaction vessel. The mixture was then heated to 105°C while nitrogen was passed through and the mixture was stirred. As an initial initiator, a solution consisting of 0.20 kg of toluene and 0.014 kg of t-amyl peroxyisononanoate was added dropwise to the polymerization tank over 10 minutes while polymerization was carried out at 105°C to 110°C. Ten minutes later, a solution consisting of 0.26 kg of toluene and 0.017 kg of t-amyl peroxyisononanoate was added dropwise over 3 hours. Simultaneously with the addition of this initiator solution, a solution consisting of 2.75 kg of methyl methacrylate, 0.40 kg of methyl 2-(hydroxymethyl)acrylate, and 0.24 kg of styrene was added dropwise over 3 hours while polymerization was carried out at a polymerization temperature of 105°C to 110°C, followed by a 2-hour maturation period. To the obtained polymer solution, a mixed solution of 4.5 g of stearyl phosphate / distearyl phosphate and 72 g of toluene was added, and a cyclization condensation reaction was carried out at 90-110°C for 1.5 hours. Subsequently, 0.10 parts by mass of Rikemar H-100 was added to 100 parts by mass of the total monomers to be charged into the final reaction vessel, and the mixture was stirred. The obtained polymerization solution was subjected to a cyclocondensation reaction and defoliation treatment using a φ42 mm defoliation extruder with 4 fore vents and 1 back vent at a barrel temperature of 220°C, 120 rpm, and a resin volume of 5 kg / hour to obtain pellets of methacrylic resin composition C. The obtained pellets had a glass transition temperature (Tg) of 127°C and a flexural strength of 98 MPa. 1 The oxygen weight percentage, determined from the monomer composition ratio obtained from the 1H-NMR composition, was 31% by weight.

[0315] (Synthesis Example 4 [Methacrylic Resin Composition D]) A twin-screw extruder with a screw diameter of 40 mm and rotating in the same direction was used. The extruder cylinder temperature was set to 275°C and the screw rotation speed to 150 rpm. Polymethyl methacrylate with a weight-average molecular weight of 108,000, including 0.1 parts by mass for every 100 parts by mass of Likemar H-100, was supplied from the hopper at a rate of 20 kg / hour, while nitrogen was flowed into the extruder at a flow rate of 200 mL / min. After the resin was melted and filled using a kneading block, 1.8 parts by mass of monomethylamine per 100 parts by mass of the raw resin was injected from the nozzle to carry out the imidation reaction. A reverse flight was placed at the end of the reaction zone (before the vent port) to fill it with resin. By-products and excess monomethylamine after the reaction were removed by reducing the pressure at the vent port to 50 Torr. The resin that came out as strands from the die provided at the extruder outlet was cooled in a water bath and then pelletized in a pelletizer to obtain imide resin. Next, using a twin-screw extruder with a screw diameter of 40 mm and rotating in the same direction, the extruder cylinder temperature was set to 255°C and the screw rotation speed to 150 rpm. The obtained imide resin was supplied at a rate of 20 kg / hr, and after the resin was melted and filled by a kneading block, a mixture of dimethyl carbonate and triethylamine was injected from the nozzle as an esterifying agent to reduce the carboxylic acid groups in the resin. The amount of dimethyl carbonate was 3.2 parts by mass and triethylamine was 0.8 parts by mass per 100 parts by mass of imide resin. By-products and excess dimethyl carbonate after the reaction were removed by reducing the pressure at the vent port to 50 Torr. The resin that came out as strands from the die provided at the extruder outlet was cooled in a water bath and then pelletized in a pelletizer to obtain pellets of methacrylic resin composition D having a glutarimide structure. The obtained pellets had a glass transition temperature (Tg) of 122°C and a flexural strength of 127 MPa. 1 The oxygen weight percentage, determined from the monomer composition ratio obtained from the 1H-NMR composition, was 31% by weight.

[0316] (Synthesis Example 5 [Methacrylic Resin Composition E]) 298.5 kg of MMA, 37.0 kg of PMI, 104.5 kg of CMI, 0.23 kg of n-octyl mercaptan (a chain transfer agent), and 247.0 kg of mXy were weighed out and placed in a 1.25 m² tank equipped with a jacketed temperature control device and stirring blades. 3 The mixture was added to the reactor and stirred to obtain a mixed monomer solution. Next, 123.0 kg of mXy was weighed and added to tank 1. Furthermore, 110.0 kg of MMA and 80.0 kg of mXy were weighed into tank 2 and stirred to prepare the monomer solution for supplementation. The contents of the reactor were bubbling with nitrogen at a rate of 30 L / min for 1 hour, and dissolved oxygen was removed from both Tank 1 and Tank 2 by bubbling with nitrogen at a rate of 10 L / min for 30 minutes. Subsequently, steam was blown into the jacket to raise the solution temperature in the reactor to 124°C. Polymerization was started by adding a polymerization initiator solution, which consisted of 0.35 kg of 1,1-di(t-butylperoxy)cyclohexane dissolved in 4.652 kg of mXy, at a rate of 1 kg / hour while stirring at 50 rpm. At the same time, mXy was added from tank 1 at a rate of 30.75 kg / hour for 4 hours. During polymerization, the solution temperature in the reactor was controlled to 124±2°C using a jacket for temperature regulation. Next, between 4 and 6 hours later, a monomer solution containing MMA was added from tank 2 at a rate of 95 kg / hour. Furthermore, the addition rate of the polymerization initiator solution was reduced to 0.25 kg / hour after 0.5 hours, 0.75 kg / hour after 4 hours, and 0.5 kg / hour after 6 hours. The addition of the polymerization initiator solution was stopped after 7 hours, and polymerization was continued for another 3 hours to obtain a polymerization solution containing a methacrylic resin having ring structural units in the main chain. To this polymerization solution, 0.83 kg of Adekastab PEP-36, 0.28 kg of Irgafos168, 0.44 kg of Irganox1076, and 1.10 kg of Rikemar H-100 were added under stirring. Next, the obtained polymerization solution was supplied to a concentration apparatus consisting of a tubular heat exchanger and a vaporization tank, which had been preheated to 260°C, for defoliation. The vacuum level in the vaporization tank was set to 10-15 Torr. The resin flowing down the vaporization tank was discharged with a screw pump, extruded from a strand die, and after water cooling, was pelletized to obtain pellets of methacrylic resin E having N-substituted maleimide structural units. The obtained pellets had a glass transition temperature (Tg) of 146°C, a melt viscosity of 210 Pa·sec, and a flexural strength of 59 MPa. 1 The oxygen weight percentage, determined from the monomer composition ratio obtained from the 1H-NMR composition, was 28% by weight.

[0317] (Synthesis Example 6 [Resin Composition F of Cyclic Olefin Copolymer]) First, VO(OC2H5)Cl2 was diluted with cyclohexane to prepare a vanadium catalyst with a vanadium concentration of 6.7 mmol / L-cyclohexane. Ethyl aluminum sesquichloride (Al(C2H5) 1.5 Cl 1.5 The solution was diluted with cyclohexane to prepare an organoaluminum compound catalyst with an aluminum concentration of 107 mmol / L-hexane. Next, using a stirred polymerizer (inner diameter 500 mm, reaction volume 100 L), ethylene and tetracyclo[4.4.0.1 2,5 .1 7,10 A copolymerization reaction with ]-3-dodecene was carried out. Here, ethylene was supplied into the polymerizer along with hydrogen gas. The flow rate of hydrogen gas was adjusted to achieve the desired molecular weight. During this copolymerization reaction, the vanadium catalyst prepared by the above method was supplied into the polymerizer in an amount such that the vanadium catalyst concentration relative to the cyclohexane used as the polymerization solvent in the polymerizer was 0.6 mmol / L. In addition, ethylaluminum sesquichloride, an organoaluminum compound, was supplied into the polymerizer in an amount such that Al / V = 18.0. The copolymerization reaction was carried out continuously at a polymerization temperature of 8°C and a polymerization pressure of 1.8 kg / cm²G. Ethylene and tetracyclo[4.4.0.1] extracted from the polymerizer 2,5 .1 7,10To the copolymer solution with ]-3-dodecene, water and a 25% by mass aqueous sodium hydroxide solution were added as a pH adjuster to stop the polymerization reaction. Furthermore, catalyst residue present in the copolymer was removed (decalcified) from this copolymer solution. The above decalcified solution of ethylene and tetracyclo[4.4.0.1 2,5 .1 7,10 A cyclohexane solution (polymer concentration 7.7% by mass) of the copolymer with ]-3-dodecene was prepared by adding Irganox1010 as a stabilizer at a ratio of 0.4 parts by mass per 100 parts by mass of copolymer. Then, before proceeding to the flash drying process, the solution was temporarily dried to an effective volume of 1.0 m³. 3 The mixture was stirred for 1 hour using a stirring tank. As a heat source: 20 kg / cm³ 2 A double-tube heater (outer tube diameter 2B, inner tube diameter 3 / 4B, length 21m) using steam G was supplied with a cyclohexane solution of the copolymer, with a copolymer concentration of 5% by mass, at a rate of 150 kg / h and heated to 180°C. As a heat source: 25 kg / cm³ 2 Using a double-tube flash dryer (outer tube diameter 2B, inner tube diameter 3 / 4B, length 27m) and a flash hopper (volume 200L) with steam G, the majority of unreacted monomers are removed from the cyclohexane solution of the copolymer after the above heating step, along with the polymerization solvent cyclohexane, thereby flash-drying the molten ethylene and tetracyclo[4.4.0.1 2,5 .1 7,10 A random copolymer (cyclic olefin copolymer) with ]-3-dodecene was obtained. The cyclic olefin copolymer was extruded using a twin-screw compounding extruder with vents, pelletized using an underwater pelletizer attached to the extruder outlet, and the resulting pellets were dried with hot air at 100°C for 4 hours to obtain the cyclic olefin copolymer resin composition F. The composition ratio of cyclic olefin copolymers 13 Confirmed by 13C-NMR measurement, the ratio of CH to CH2 indicated that the predetermined amount of olefin was 62 mol% and tetracyclo[4.4.0.1 2,5 .17,10 It was confirmed that ]-3-dodecene was copolymerized at a ratio of 38 mol%. The glass transition temperature (Tg) was 142°C, and the flexural strength was 78 MPa. Furthermore, the oxygen weight percentage, calculated from the monomer composition ratio, was 0% by weight. Other properties are listed in the table.

[0318] (Synthesis Example 7 [Methacrylic Resin Composition G]) In a 30L reaction vessel equipped with a paddle blade agitator, temperature sensor, condenser, and nitrogen inlet, 2.25 kg of methyl methacrylate, 1.25 kg of methyl 2-(hydroxymethyl)acrylate, 0.025 parts by mass of n-dodecyl mercaptan and 0.025 parts of Adekastab 2112 per 100 parts by mass of the total monomers as chain transfer agents, and 6.25 kg of toluene were charged, and the mixture was heated to 105°C while passing nitrogen through it and stirring. While refluxing, 0.05 parts by mass of t-amyl peroxyisononanoate were added to the polymerization vessel per 100 parts by mass of the total amount of monomers. Then, 0.1 parts by mass of t-amyl peroxyisononanoate were added dropwise over 2 hours, and polymerization was carried out under reflux at a polymerization temperature of 105-110°C, and the polymerization reaction was continued for a further 6 hours. To the obtained polymer solution, 6.3 g of stearyl phosphate / distearyl phosphate mixture was added, and a cyclization condensation reaction was carried out at 90-110°C for 5 hours. Subsequently, 0.15 parts by mass of Rikemar H-100 was added per 100 parts by mass of the total monomer amount, and the mixture was stirred and mixed. The obtained polymerization solution was subjected to a cyclization condensation reaction and defoliation treatment using a φ42 mm defoliation extruder with 4 fore vents and 1 back vent at 120 rpm and a resin volume equivalent to 2.2 kg / hour, to obtain pellets of methacrylic resin composition H. The obtained pellets had a glass transition temperature (Tg) of 133°C and a flexural strength of 71 MPa. 1 The oxygen weight percentage, determined from the monomer composition ratio obtained from the 1H-NMR composition, was 33% by weight.

[0319] (Synthesis Example 8 [Methacrylic Resin Composition J]) 381 kg of MMA, 0 kg of PMI, 37 kg of CMI, 0.38 kg of n-octyl mercaptan (a chain transfer agent), and 25.1 kg of mXy were weighed out and placed in a 1.25 m² tank equipped with a jacketed temperature control device and stirring blades. 3 The mixture was added to the reactor and stirred to obtain a mixed monomer solution. Then, pellets of resin composition J were obtained in the same manner as in Synthesis Example 1. The obtained pellets had a glass transition temperature (Tg) of 124°C and a flexural strength of 110 MPa. 1 The oxygen weight percentage, determined from the monomer composition ratio obtained from the 1H-NMR composition, was 30.9% by weight.

[0320] (Example 1) [Shaping of light guide components] The methacrylic resin composition A obtained in Synthesis Example 1 was used for injection molding using an injection molding machine (FANUC S-2000i50B, screw diameter φ26 mm). A mold was used to obtain a light guide member with the shape shown in Figure 10A (thickness between the waveguide sections is 2.9 mm, the waveguide distance of the main ray within the light guide member is 21 mm, and the projected length in the waveguide direction is 18 mm). The light incident section, the external-side waveguide section, the eye-side waveguide section (including the light emission section), and the output coupler are all planar. The cylinder temperature was set to Tg + 120°C of the resin composition used, and the mold temperature was set to the actual temperature of Tg - 15°C of the resin composition used, and the base material portion of the light guide member was molded. The holding pressure was set to 105 MPa for 5 seconds in the first stage, and then to 70 MPa for 3 seconds in the second holding stage to relieve stress strain inside the molded product. The injection speed was set to an initial speed of 5 mm / s, reduced to 1 mm / s at the gate, and filled at 4 mm / s after passing the gate, and injection molding was performed to obtain the light guide member according to Example 1. The surface shape of the obtained molded piece was measured and placed on a metal tray. The shape of each surface of the light guide member was measured using NH-3SPs (manufactured by Mitaka Kohki Co., Ltd.), and the molding conditions were adjusted as appropriate to obtain the desired shape, thereby obtaining a light guide member of the predetermined shape.

[0321] Next, the waveguide members were cleaned using a cleaning solution containing water and a surfactant by ultrasonic treatment. After vacuum drying at 70°C for 6 hours, an anti-reflective coating was applied to the light incident section, and partial mirrors with a reflectivity of 35% in the unpolarized state were deposited on the external-side and eye-side waveguide sections and the output coupler. At a wavelength of 530 nm and an incident angle of 30 degrees, the Rs / Rp ratio of the partial mirror was 1.8, and the reflectivity difference between Rs and Rp was 17%. Furthermore, the in-plane phase difference within the effective area of ​​the waveguide (the projected area of ​​the measurement area relative to the total projected area of ​​the measurement surface was 90%) was 13 nm. The PV values ​​for each surface were 2 μm for the light incident area, 7.1 μm for the external waveguide, 12.3 μm for the eye-side waveguide, and 10.4 μm for the output coupler. Table 1 shows the results of other evaluations conducted on the light guide material. The PV values ​​for each surface the day after molding were 1.3 μm for the light incident area, 4.5 μm for the external waveguide area, 5.6 μm for the eye-side waveguide area, and 4.6 μm for the output coupler. However, after 5 days, the PV values ​​for each surface were 2.2 μm for the light incident area, 6.7 μm for the external waveguide area, 11.5 μm for the eye-side waveguide area, and 10.5 μm for the output coupler.

[0322] (Example 2) After injection molding in Example 1, the molded piece, with the gate not cut and the runner and sprue remaining, was placed on a plastic tray with the sprue, and the runner portion was secured with cellophane tape so that the light guide member was suspended in mid-air as shown in Figure 12. The piece was then left to stand for one day in a room where the temperature was controlled to 23°C. After that, vapor deposition was performed in the same manner as in Example 1, and various measurements were carried out. Furthermore, the PV values ​​for each surface were 0.9 μm for the light incident area, 1.4 μm for the external waveguide area, 3.6 μm for the eye-side waveguide area, and 4.2 μm for the output coupler. Table 1 shows the results of other evaluations conducted on the light guide material.

[0323] (Example 3) The light guide member was fabricated in the same manner as in Example 2, except that partial mirrors were used to set the reflectivity of the external-side waveguide, the eye-side waveguide, and the output coupler to 40%. At a wavelength of 530 nm, the Rs / Rp ratio of the partial mirror at an incident angle of 30 degrees was 1.4, and the reflectivity difference between Rs and Rp was 13%. Table 1 shows the results of other evaluations conducted on the light guide material.

[0324] (Example 4) The light guide member was fabricated in the same manner as in Example 2, except that partial mirrors were used to set the reflectivity of the external-side waveguide, the eye-side waveguide, and the output coupler to 50%. At a wavelength of 530 nm, the Rs / Rp ratio of the partial mirror at an incident angle of 30 degrees was 1.3, and the reflectivity difference between Rs and Rp was 15%. Table 1 shows the results of other evaluations conducted on the light guide material.

[0325] (Example 5) A light guide member was fabricated in the same manner as in Example 2, except that a mold was used to obtain a light guide member with the shape of Figure 10B (thickness between waveguide sections is 5.0 mm, waveguide distance of the main ray within the light guide member is approximately 21 mm, and projection length in the waveguide direction is 30 mm), and a partial mirror was applied with a reflectivity of 50% for the external-side waveguide section, the eye-side waveguide section and the output coupler, Rs / Rp = 3.0 at an incident angle of 30 degrees at a wavelength of 530 nm, a reflectivity difference between Rs and Rp of 50%, and a reflectivity difference between Rs and Rp of 30% at an incident angle of 5 degrees. Table 1 shows the results of other evaluations conducted on the light guide material.

[0326] (Example 6) The light guide members were manufactured in the same manner as in Example 2, except that the light guide members obtained after injection molding were annealed at 115°C for 1 hour before proceeding to the process of applying vapor deposition to each surface. The PV values ​​for each surface were 2.1 μm for the light incident area, 3.2 μm for the external waveguide, 8.5 μm for the eye-side waveguide, and 8.1 μm for the output coupler. Table 1 shows the results of other evaluations conducted on the light guide material.

[0327] (Example 7) The light guide members were manufactured in the same manner as in Example 2, except that the light guide members obtained after injection molding were annealed at 85°C for 4 hours before proceeding to the process of applying vapor deposition to each surface. The PV values ​​for each surface were 1.0 μm for the light incident area, 2.2 μm for the external waveguide, 5.1 μm for the eye-side waveguide, and 4.5 μm for the output coupler. Table 1 shows the results of other evaluations conducted on the light guide material.

[0328] (Example 8) 100 parts by mass of methacrylic resin composition A obtained in Synthesis Example 1 was dry-blended with 1.3 parts by mass of pentaerythritol tetrastearate (Unistar H-476, manufactured by NOF Corporation), a fatty acid ester consisting of a tetrahydric alcohol and a fatty acid. Using a twin-screw extruder with a vent (screw diameter 30 mm, L / D = 60, Omega30H, manufactured by STEER JAPAN), the resulting blend pellets were supplied to a hopper under a nitrogen atmosphere and melt-kneaded at a cylinder temperature of 250°C and a resin pressure of 10 kg / h. After water cooling in a water bath, the mixture was pelletized using a pelletizer to obtain resin composition H. The weight-average molecular weight of the obtained pellets was 123,000, and the residual amount of pentaerythritol tetrastearate was 0.8% by weight. The light guide member was fabricated under the same conditions as in Example 2, except that the resin composition obtained in this way was used. Table 1 shows the results of other evaluations conducted on the light guide material.

[0329] (Example 9) The light guide members were manufactured in the same manner as in Example 8, except that the light guide members obtained after injection molding were annealed at 85°C for 4 hours before proceeding to the process of vapor deposition on each surface. Table 1 shows the results of other evaluations conducted on the light guide material.

[0330] (Examples 10-13) The light guide members were fabricated under the same conditions as in Example 1, except that resin compositions B to E obtained in each synthesis example were used. Table 2 shows the evaluation results for the light guide component.

[0331] (Example 14) 100 parts by mass of the methacrylic resin composition F obtained in Synthesis Example 6 was dry-blended with 1.2 parts by mass of pentaerythritol distearate (Unistar H-476D, manufactured by NOF Corporation), a fatty acid ester consisting of a tetrahydric alcohol and a fatty acid. The resulting blend pellets were supplied to a hopper under a nitrogen atmosphere using a twin-screw extruder with a vent (screw diameter 30 mm, L / D = 60, Omega30H, manufactured by STEER JAPAN), and melt-kneaded at a cylinder temperature of 250°C and a resin pressure of 10 kg / h. After water cooling in a water bath, the mixture was pelletized using a pelletizer to obtain resin composition I. The weight-average molecular weight of the obtained pellets was 90,000, and the residual amount of pentaerythritol distearate was 0.9% by weight. Other characteristics are described in Table 2. The cyclic olefin copolymer obtained in the pellets contained a predetermined amount of olefin, which was 62 mol% and cyclotetracyclo[4.4.0.1 2,5 .1 7,10 It was confirmed that ]-3-dodecene was copolymerized at a ratio of 38 mol%. The glass transition temperature (Tg) was 137°C and the flexural strength was 77 MPa. The oxygen weight percentage, calculated from the monomer composition ratio, was 0% by weight.

[0332] The resin composition I obtained in this manner was used for injection molding using an injection molding machine (FANUC S-2000i50B, screw diameter φ26 mm). A light guide member with the shape shown in Figure 10A was used as the mold. The light incident section, the external field side waveguide section, the eye side waveguide section (including the light emission section), and the output coupler are all planar. The cylinder temperature was set to Tg + 120°C of the resin composition used, and the mold temperature was set to the actual temperature of the resin composition Tg - 15°C, and the light guide member was molded. The holding pressure was set to 125 MPa for 5 seconds in the first stage, and then to 90 MPa for 3 seconds in the second stage to relieve stress strain inside the molded product. The injection speed was set to an initial speed of 5 mm / s, reduced to 1 mm / s at the gate, and then filled at 4 mm / s after passing the gate to perform injection molding. The resulting molded pieces were left undisturbed for one day, with the gates left intact and the runners and sprues still attached. The sprue portion was hung on a test tube rack, and the light guide portion was suspended in the air. Subsequently, deposition was carried out in the same manner as in Example 1, and various measurements were performed.

[0333] The obtained molded pieces were cleaned by ultrasonic treatment using a cleaning solution containing water and a surfactant. After vacuum drying at 80°C for 6 hours, they were annealed. They were held in an oven at 130°C for 2 hours, then slowly cooled to 90°C over 1 hour, and held for 1 hour after reaching 90°C before being removed. An anti-reflective coating was applied to the incident surface, and a partial mirror with a reflectivity of 35% in the unpolarized state was deposited on the external and eye-side waveguides and the output coupler. At a wavelength of 530 nm and an incident angle of 30 degrees, the Rs / Rp of the partial mirror was 1.8, and the reflectivity difference between Rs and Rp was 17%. The PV values ​​for each surface were 1.8 μm for the light incident surface, 3.3 μm for the external waveguide, 6.5 μm for the eye-side waveguide, and 6.2 μm for the output coupler. Table 2 shows the results of other evaluations conducted on the light guide material.

[0334] (Example 15) A light guide member was obtained in the same manner as in Example 14, except that the annealing process was changed to holding at 90°C for 4 hours. The in-plane phase difference within the effective area of ​​the waveguide (the projected area of ​​the measurement area relative to the total projected area of ​​the measurement surface was 90%) was 5 nm. The PV values ​​for each surface were 1.0 μm for the light incident area, 1.2 μm for the external waveguide, 3.6 μm for the eye-side waveguide, and 4.5 μm for the output coupler. Table 2 shows the results of other evaluations conducted on the light guide material.

[0335] (Example 16) The light guide members were fabricated under the same conditions as in Example 1, except that the resin composition J obtained in Synthesis Example 8 was used. The evaluation results of the light guide members are shown in Table 2.

[0336] (Comparative Example 1) The light guide member was fabricated in the same manner as in Example 2, except that the resin composition G obtained in Synthesis Example 7 was used. The evaluation results are shown in Table 2.

[0337] (Comparative Example 2) The light guide member was prepared in the same manner as in Example 14, except that the resin composition F obtained in Synthesis Example 6 was used as is without compounding with pentaerythritol distearate, and the annealing process was not performed. The evaluation results for the light guide component are shown in Table 2.

[0338] (Comparative Example 3) The light guide member was fabricated in the same manner as in Example 2, except that ZEONEX K22R manufactured by Nippon Zeon Corporation was used as the resin composition. The evaluation results for the light guide component are shown in Table 2.

[0339] [Table 1]

[0340] [Table 2]

[0341] Tables 1 and 2 show that, even when partial mirrors with polarization-selective reflectivity characteristics are configured in the input coupler, waveguide section, and output coupler, the light guide member of this embodiment can provide high-resolution images without distortion while suppressing defects such as brightness unevenness, color unevenness, and rainbow appearance.

[0342] (Example 17) The methacrylic resin composition A obtained in Synthesis Example 1 was used for injection molding using an injection molding machine (FANUC S-2000i50B, screw diameter φ26 mm). A mold was used to obtain a light guide member (thickness between waveguide sections is 2.0 mm, projected length in the waveguide direction of the light guide member is 26 mm) and a correction member with the shape shown in Figure 13. The light incident section, the external-side waveguide section, the eye-side waveguide section (including the light emission section), and the output coupler are all planar. The cylinder temperature was set to Tg + 125°C of the resin composition used, and the mold temperature was set to the actual temperature of the resin composition Tg - 15°C for molding. The holding pressure was set to 105 MPa for 5 seconds in the first stage, and then to 70 MPa for 3 seconds in the second stage to relieve stress strain inside the molded product. The injection speed was set to an initial speed of 5 mm / s, reduced to 1 mm / s at the gate, and filled at 4 mm / s after passing the gate, and injection molding was performed to obtain the desired light guide member and correction member. The gate of the obtained molded piece was not cut, and the molded piece with the runner and sprue remaining was placed on a plastic tray with the sprue, and the runner portion was fixed with cellophane tape so that the light guide member was suspended in the air as shown in Figure 12, and left to stand for 1 day in a room where the temperature was controlled to 23°C. The shapes of each surface of the light guide member and the correction member were measured using NH-3SPs (manufactured by Mitaka Kohki Co., Ltd.), and the molding conditions were adjusted as appropriate to obtain the predetermined shape of the light guide member.

[0343] Next, the waveguide members were cleaned using a cleaning solution containing water and a surfactant by ultrasonic treatment. After vacuum drying at 70°C for 6 hours, an anti-reflective coating was applied to the light incident portion of the light guide member, and a partial mirror with a reflectivity of 35% in the unpolarized state was deposited on the external-side waveguide portion, the eye-side waveguide portion, and the output coupler of the light guide member. At a wavelength of 530 nm and an incident angle of 30°, the Rs / Rp ratio of the partial mirror was 1.8, and the reflectivity difference between Rs and Rp was 17%. The light guide and correction members were bonded together using adhesive. After arranging the image display eleme...

Claims

1. An injection-molded light guide member for use in an image display device having an eyepiece optical system that guides light from an image display element toward the observer's eyeball, The base material and, An input coupler for causing light from the image display element to enter the light guide body, Two opposing waveguide sections guide the incident light through multiple repeated reflections, It comprises an output coupler for extracting light from a light guide member towards the observer's eye by bending, diffraction, or reflection, The absolute value of the photoelastic coefficient is 10 × 10 －１２ Pa －１ The following: Of the three surfaces in total—the two waveguide surfaces and the output coupler surface—at least one surface has a partial mirror that transmits a portion of the light and reflects the remaining portion. The partial mirror has a reflectivity difference of 10% or more and less than 40% between a first polarization that becomes S-polarized and a second polarization that is orthogonal to the first polarization when reflected by the partial mirror at an incident angle of 30°, and P-polarized. The waveguide portion has an in-plane phase difference of 20 nm or less within its effective area. The aforementioned base material is composed of a thermoplastic resin composition having a ring structure in the main chain or side chain, and is characterized by having a glass transition temperature (Tg) of 115 to 150°C, wherein the injection-molded light guide member is characterized by this composition.

2. The shortest distance between the two waveguide sections is 0.6 mm or more and 25 mm or less. The projection length of the light guide member in the direction of wave guidance is 10 mm or more and 50 mm or less. The injection-molded light guide member according to claim 1, characterized in that the PV value in the effective area where light is guided is 10.0 μm or less for both of the two wave-guiding surfaces.

3. One of the two waveguide sections is the external-side waveguide section. The injection-molded light guide member according to claim 1 or 2, characterized in that the external-side wave guide portion is formed with a partial mirror that transmits a portion of the light and reflects the remaining portion.

4. An injection-molded light guide member according to claim 1 or 2, characterized in that when a first polarization of 500 to 600 nm with a wavelength that becomes S-polarized upon reflection in the waveguide section is incident, and after the light is guided in the waveguide section, and the light is extracted from the light extraction section via an output coupler, the ratio (Tp / Tc) of the amount of light extracted via a polarizer arranged so that the axis of the first polarization coincides with the transmission axis and the amount of light extracted via a polarizer arranged so that the axis of the first polarization coincides with the transmission axis is 5 or more when the ratio (Rs / Rp) of the part of the partial mirror with the largest ratio of S-polarized reflectance to P-polarized reflectance (Rs / Rp) is divided by the ratio (Rs / Rp) of the surface with the largest ratio (Rs / Rp) of S-polarized reflectance to P-polarized reflectance.

5. The injection-molded light guide member according to claim 4, characterized in that the value obtained by dividing the ratio (Tp / Tc) by the ratio (Rs / Rp) of the surface with the largest ratio (Rs / Rp) is 10 or more.

6. The injection-molded light guide member according to claim 1 or 2, characterized in that the output coupler has a partial mirror formed therein that transmits a portion of the light and reflects the remaining portion.

7. The injection-molded light guide member according to claim 1 or 2, characterized in that the thermoplastic resin composition contains 0.5 to 2.8% by mass of a higher fatty acid ester.

8. The injection-molded light guide member according to claim 1 or 2, characterized in that the thermoplastic resin composition is a methacrylic resin composition.

9. A head-mounted display characterized by comprising an injection-molded light guide member as described in claim 1 or 2.

10. A head-mounted display according to claim 9, A head-mounted display characterized in that, in at least one of the optical output section and the eye-side waveguide section, the reflectance of S-polarized light at an incident angle of 5° is greater than the reflectance of P-polarized light, and the difference between the reflectance of S-polarized light and P-polarized light is 5% or more.

11. A head-mounted display according to claim 9, Partial mirrors are formed on both sides of the two waveguide sections, either partially or entirely, which transmit a portion of the light and reflect the remaining portion. A head-mounted display characterized by guiding light at an incident angle smaller than the critical angle of the substrate portion.

12. A head-mounted display according to claim 9, A head-mounted display characterized by having a linear polarizing plate on a straight line extending outwards from the observer's eyeball to the output coupler of the light guide member.

13. A head-mounted display according to claim 9, A head-mounted display characterized in that it has a linear polarizing plate and a half-wave plate or a phase difference layer that imparts a half-wave phase difference, in order from the outside side along a straight line extending to the outside world, connecting the observer's eyeball and the output coupler of the light guide member.

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