Resin polarization beam splitter

Abstract

To provide a resin polarization beam splitter in which an optical performance is inhibited from deteriorating under a high-temperature and humidification environment and which obtains clear video.SOLUTION: The resin polarization beam splitter comprises: a first resin base material; a second resin base material facing the first resin base material; a reflection type polarization element disposed between the first resin base material and the second resin base material; a first adhesion layer disposed between the first resin base material and the reflection type polarization element; and a second adhesion layer between the second resin base material and the reflection type polarization element; and a silane coupling agent layer disposed between at least one of between the first resin base material and the first adhesion layer, between the first adhesion layer and the reflection type polarization element, between the reflection type polarization element and the second adhesion layer, and between the second adhesion layer and the second resin base material.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin polarizing beam splitter. [Background technology]

[0002] In recent years, various electronic technologies known as VR (Virtual Reality) and AR (Augmented Reality) have rapidly developed, and head-mounted display (HMD) products have begun to spread as image display devices for these technologies. An optical system has been proposed in which a polarizing beam splitter (PBS) is placed in the image projection unit or image display unit of the HMD (Patent Document 1). Since head-mounted displays are image display devices worn on the head, they are required to be small, lightweight, and comfortable to wear, and attempts have been made to manufacture polarizing beam splitters using resin prisms to reduce weight.Since resins generally tend to exhibit birefringence during molding, resin prisms have been proposed that reduce birefringence by using low-birefringence resins that are less likely to exhibit birefringence (Patent Documents 2 and 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-101424 [Patent Document 2] Patent Publication No. 2021-157158 [Patent Document 3] Patent No. 7312546 Summary of the Invention [Problem to be solved by the invention]

[0004] When manufacturing a polarizing beam splitter using resin, it is often done by bonding a resin substrate and a polarization separation film together using an adhesive. Resin polarizing beam splitters are superior to glass polarizing beam splitters in terms of reducing the weight of image display devices, but they have the issue of being highly water-absorbent. In high-temperature, humid environments, the resin substrate and the polarization separation film can deform due to moisture absorption, and the difference in dimensional change caused by moisture absorption can sometimes cause delamination at the adhesive layer interface. Polarizing beam splitters that experience this delamination have the problem of significantly reduced optical performance (polarization separation ability and transmittance). In particular, when a polarizing beam splitter is manufactured using a molded body such as a resin rectangular prism, which has a different thickness (non-uniform thickness) between the edges and the center, the inventors' investigations have revealed that peeling is likely to occur between the resin rectangular prism and the polarizing separation film in a high-temperature, humid environment because the shape changes non-uniformly when the body absorbs moisture.

[0005] The present invention has been made in consideration of the above problems, and aims to provide a resin polarizing beam splitter that suppresses deterioration of optical performance in a high-temperature and humid environment and provides clear images. [Means for solving the problem]

[0006] As a result of extensive research, the present inventors have completed the invention described below. That is, the present invention is as follows. [1] a first resin substrate; a second resin base material facing the first resin base material; a reflective polarizing element disposed between the first resin base material and the second resin base material; a first adhesive layer disposed between the first resin substrate and the reflective polarizing element; a second adhesive layer disposed between the second resin substrate and the reflective polarizing element; a silane coupling agent layer disposed between at least one of the first resin substrate and the first adhesive layer, the first adhesive layer and the reflective polarizing element, the reflective polarizing element and the second adhesive layer, and the second adhesive layer and the second resin substrate; A resin polarizing beam splitter comprising: [2] The resin polarizing beam splitter according to [1], which has a glass transition temperature (Tg) of 115°C to 160°C. [3] The absolute value of the photoelastic coefficient is 10 × 10 -12 Pa -1 The resin polarizing beam splitter according to [1] or [2], which is: [4] The resin polarizing beam splitter according to any one of [1] to [3], wherein the first resin base material and the second resin base material contain a methacrylic resin. [5] The resin polarizing beam splitter according to [4], wherein the methacrylic resin includes a methacrylic resin having a structural unit with a ring structure. [6] The resin polarizing beam splitter according to [5], wherein the structural unit contains at least one structural unit selected from the group consisting of a structural unit derived from an N-substituted maleimide monomer, a glutarimide structural unit, an aromatic vinyl structural unit, an alicyclic vinyl structural unit, and a lactone ring structural unit. [7] The resin polarizing beam splitter according to [5] or [6], wherein the structural unit includes a structural unit derived from an N-substituted maleimide monomer. [8] The resin polarizing beam splitter according to any one of [1] to [7], wherein the reflective polarizing element contains a cyclic olefin resin. [9] The resin polarizing beam splitter according to any one of [1] to [8], wherein the first adhesive layer and / or the second adhesive layer contains a photocurable acrylic adhesive.

[10] A polarization conversion element comprising the resin polarization beam splitter according to any one of [1] to [9]. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a resin polarizing beam splitter that can suppress deterioration of optical performance in a high-temperature and humid environment and can provide a clear image. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of an experimental system prepared for evaluating the characteristics of the resin polarizing beam splitter of the present invention in the examples. [Figure 2] FIG. 2 is a schematic cross-sectional view of a wire grid reflective polarizing element. [Figure 3] 3 is a schematic diagram of an experimental system constructed to measure the polarization retention. (a) shows an experimental system in which S-polarized light is emitted from a light source 41, and the amount of light that is reflected by a polarizing beam splitter 40 and then transmitted through a second linear polarizer 43 is measured with a power meter 44. (b) shows an experimental system in which P-polarized light is emitted from a light source 41, and the amount of light that is transmitted through a polarizing beam splitter 40 and then transmitted through a second linear polarizer 43 is measured with a power meter 44. DETAILED DESCRIPTION OF THE INVENTION

[0009] Below, we will explain in detail the form for implementing the present invention (hereinafter referred to as the ``present embodiment''), but the present invention is not limited to the following description and can be implemented in various modifications within the scope of the paper.

[0010] <Resin polarized beam splitter> The resin polarizing beam splitter of this embodiment (hereinafter also simply referred to as "polarizing beam splitter") is characterized by comprising a first resin substrate, a second resin substrate facing the first resin substrate, a reflective polarizing element arranged between the first resin substrate and the second resin substrate, a first adhesive layer arranged between the first resin substrate and the reflective polarizing element, a second adhesive layer arranged between the second resin substrate and the reflective polarizing element, and a silane coupling agent layer arranged between at least one of the following: between the first resin substrate and the first adhesive layer, between the first adhesive layer and the reflective polarizing element, between the reflective polarizing element and the second adhesive layer, and between the second adhesive layer and the second resin substrate. That is, in the resin polarizing beam splitter of this embodiment, the structure between the first resin substrate and the reflective polarizing element may be, for example, first resin substrate / silane coupling agent layer / first adhesive layer / silane coupling agent layer / reflective polarizing element, or first resin substrate / first adhesive layer / silane coupling agent layer / reflective polarizing element, or first resin substrate / silane coupling agent layer / first adhesive layer / reflective polarizing element. Furthermore, the structure between the second resin substrate and the reflective polarizing element may be, for example, second resin substrate / silane coupling agent layer / second adhesive layer / silane coupling agent layer / reflective polarizing element, or second resin substrate / second adhesive layer / silane coupling agent layer / reflective polarizing element, or second resin substrate / silane coupling agent layer / second adhesive layer / reflective polarizing element.

[0011] The polarizing beam splitter of this embodiment may have one or more transparent layers disposed between the first resin substrate and the silane coupling agent layer and / or between the second resin substrate and the silane coupling agent layer, i.e., may have a structure of first resin substrate / transparent layer / silane coupling agent and / or a structure of second resin substrate / transparent layer / silane coupling agent. Examples of the transparent layer include a hard coat layer, an anchor coat layer, etc. The thickness of these transparent layers is not particularly limited, but may be in the range of 0.01 to 10 μm, for example.

[0012] The surface of the polarizing beam splitter of this embodiment may be further subjected to a surface functionalization treatment such as hard coating, anti-reflection treatment, transparent conductive treatment, electromagnetic wave shielding treatment, gas barrier treatment, etc., to provide a functional layer (hard coating layer, anti-glare layer, anti-reflection layer, etc.) There are no particular restrictions on the thickness of these functional layers, but they may be in the range of 0.01 to 10 μm, for example.

[0013] The hard coat layer applied to the surface of the polarizing beam splitter can be formed by applying a coating liquid, for example, obtained by dissolving or dispersing an acrylate such as a silicone-based curable resin, an organic polymer composite inorganic particle-containing curable resin, urethane acrylate, epoxy acrylate, or polyfunctional acrylate, and a photopolymerization initiator in an organic solvent, onto the first resin substrate and / or the second resin substrate that form the polarizing beam splitter of this embodiment using a conventionally known coating method, drying the coating, and photo-curing the coating. Furthermore, in order to improve adhesion before applying the hard coat layer, a method can also be used in which, for example, an easy-adhesion layer containing inorganic fine particles, a primer layer, an anchor layer, or the like is previously provided, and then the hard coat layer is formed. The antiglare layer to be applied to the surface of the polarizing beam splitter can be formed by forming fine particles of silica, melamine resin, acrylic resin, etc. into an ink, applying it onto other functional layers by a conventionally known application method, and then heat-curing or photo-curing it. Examples of antireflection layers to be applied to the surface of the polarizing beam splitter include those made of thin films of inorganic materials such as metal oxides, fluorides, silicides, borides, nitrides, and sulfides, and those made by laminating single or multiple layers of resins with different refractive indices such as acrylic resins and fluororesins.Furthermore, those made by laminating thin layers containing composite fine particles of inorganic compounds and organic compounds can also be used.

[0014] The polarization beam splitter of this embodiment preferably has a polarization retention of 95% or more, more preferably 98% or more, and even more preferably 99% or more. When the polarization retention is within the above range, the polarization state of light transmitted through the polarization beam splitter tends to be maintained constant before and after incidence, and optical properties are less likely to be adversely affected. From the viewpoint of suppressing in-plane retardation, the material constituting the polarization beam splitter is preferably a methacrylic resin composition. The polarization retention can be measured by the method described in the examples below.

[0015] The polarizing beam splitter of this embodiment preferably has a birefringence value, expressed as the average absolute value of the in-plane retardation, of 10 nm or less, more preferably 5 nm or less, and even more preferably 3 nm or less. When the in-plane retardation is in the above range, the polarization of light transmitted through the polarizing beam splitter tends to be maintained constant, and the optical properties are less likely to be adversely affected. The in-plane retardation can be measured by the method described in the examples below.

[0016] The polarizing beam splitter of this embodiment preferably has a glass transition temperature (Tg) of 115 to 160°C, as measured by the midpoint method in accordance with JIS-K7121. A glass transition temperature (Tg) of 115°C or higher reduces the occurrence of shape deformation such as warping in reliability tests such as high-temperature aging tests, and tends to prevent adverse effects on optical properties. On the other hand, a glass transition temperature (Tg) of 160°C or lower tends to avoid melt processing at extremely high temperatures, suppress thermal decomposition of resins, etc., and produce a good product. From the viewpoint of further achieving the above-mentioned effects, the glass transition temperature (Tg) is preferably 115 to 150°C, more preferably 120 to 145°C, and particularly preferably 125 to 140°C. The glass transition temperature is measured using a differential scanning calorimeter for the resin compositions constituting the first resin substrate and the second resin substrate, and specifically, can be measured by the method described in the examples below.

[0017] The photoelastic coefficient (C R ) absolute value of |C R | is 10 x 10 -12 Pa -1 It is preferably equal to or less than 5.0 × 10 -12 Pa -1 or less, and more preferably 3.0 × 10 -12 Pa -1 and even more preferably 1.0×10 -12 Pa -1 The photoelastic coefficient (C R ) absolute value of |C R | is 10 x 10 -12 Pa -1 If the photoelastic coefficient (C R ) absolute value of |C R The lower limit of | is not particularly limited. In addition, the photoelastic coefficient (C R ) is measured by pressing the resin compositions constituting the first resin substrate and the second resin substrate into a film using a vacuum compression molding machine. When the polarizing beam splitter has functional layers such as a hard coat layer or an anti-reflection layer on its surface, the functional layers are removed before the measurement. Specifically, it can be determined by the method described in the Examples below.

[0018] The total light transmittance of the polarizing beam splitter of this embodiment is preferably 85% to 100%, more preferably 87.5% to 99%, and even more preferably 90% to 99%. If the total light transmittance is within the above range, it can be more suitably used as a polarizing beam splitter. The total light transmittance is a value measured in accordance with JIS K 7361 for the resin compositions constituting the first resin substrate and the second resin substrate, and specifically, can be measured by the method described in the examples below.

[0019] The resin composition contained in the polarizing beam splitter of this embodiment preferably has a low viscosity corresponding to the time of injection and a high fluidity in consideration of processability during injection molding. -1 In this case, the melt 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. When the melt viscosity is 20 Pa·sec or higher, it is easy to control the flow of the resin during injection, and it tends to be easy to mold the desired shape. On the other hand, when the melt viscosity is 235 Pa·sec or lower, the resin has good fluidity and good processability, and molding defects such as poor filling tend to be less likely to occur. The melt viscosity is a value measured in accordance with JIS-K7199, and specifically, can be measured by the method described in the examples below.

[0020] <First resin substrate and second resin substrate> The polarizing beam splitter of this embodiment includes a first resin base material and a second resin base material facing each other. The size and shape of the first resin base material and the second resin base material are not particularly limited and may be adjusted appropriately depending on the size and shape of the desired polarizing beam splitter. Typically, both the first resin base material and the second resin base material are triangular prisms (prisms) whose base surfaces are right-angled isosceles triangles. In this case, the first resin base material and the second resin base material are arranged so that the faces of the triangular prisms containing the hypotenuses of the base surfaces face each other, and a reflective polarizing element is arranged between the opposing faces. The first resin base material and the second resin base material may be the same or different in size and shape, but it is preferable that they are both the same in size and shape.

[0021] (Resin composition) The resin composition constituting the first resin substrate and the second resin substrate of this embodiment is not particularly limited as long as it contains a resin that has transparency, low birefringence, and heat resistance that does not impair the function of the polarizing beam splitter, and known resin compositions can be used without any particular restrictions. The first resin base material and the second resin base material may be made of the same material or different materials. The first resin substrate and the second resin substrate preferably contain a methacrylic resin composition, and more preferably consist of a methacrylic resin composition, because this allows for highly low birefringence characteristics to be achieved.

[0022] ((Methacrylic resin composition)) The methacrylic resin composition contains a methacrylic resin. In addition to the methacrylic resin, the methacrylic resin composition may optionally contain additives, or may contain a thermoplastic resin other than the methacrylic resin, a rubbery polymer, or the like.

[0023] -Methacrylic resin- The methacrylic resin contained in the methacrylic resin composition will be described below. The methacrylic resin is not particularly limited, and examples thereof include resins primarily composed of structural units derived from methyl methacrylate, such as homopolymers of methyl methacrylate and copolymers of methyl methacrylate with one or more copolymerizable monomers such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, butyl acrylate, acrylonitrile, acrylic acid, methacrylic acid, vinylpyridine, vinylmorpholine, vinylpyridone tetrahydrofurfuryl acrylate, N,N-dimethylaminoethyl acrylate, N,N-dimethylacrylamide, 2-hydroxyacrylate, 2-(hydroxymethyl)ethyl acrylate, ethylene glycol monoacrylate, glycerin monoacrylate, maleic anhydride, N-cyclohexylmaleimide, N-phenylmaleimide, styrene, and α-methylstyrene. Other examples include heat-resistant methacrylic resins having a structural unit derived from methyl methacrylate and a lactone ring or glutarimide in the main chain, and methyl methacrylate and low-moisture-absorbing methacrylic resins. These may be used alone or in a blend of two or more. The phrase "mainly composed of structural units derived from methyl methacrylate" means that structural units derived from methyl methacrylate account for 50% by mass or more of the structural units in the methacrylic resin.

[0024] In view of transparency and heat resistance, the methacrylic resin in this embodiment is preferably a methacrylic resin having a structural unit with a ring structure. The structural unit having a ring structure preferably contains at least one structural unit selected from the group consisting of a structural unit derived from an N-substituted maleimide monomer, a glutarimide structural unit, an aromatic vinyl structural unit, an alicyclic vinyl structural unit, and a lactone ring structural unit. Furthermore, it is particularly preferred that the structural unit having a ring structure contains a structural unit derived from an N-substituted maleimide monomer, since this makes it easy to highly control optical properties such as intrinsic birefringence and photoelastic coefficient without blending with other thermoplastic resins.

[0025] --Structural units derived from N-substituted maleimide monomers-- Next, the structural unit derived from the N-substituted maleimide monomer will be described. The structural unit derived from the N-substituted maleimide monomer may be at least one structural unit selected from the group consisting of structural units represented by the following formula (1) and structural units represented by the following formula (2), and is preferably formed from both structural units represented by the following formula (1) and the following formula (2).

[0026] [ka] In formula (1), R 1 represents an arylalkyl group having 7 to 14 carbon atoms or an aryl group having 6 to 14 carbon atoms, and R 2 and R 3 each independently represents 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, R 2 or R 3 When is an aryl group, R 2 or R 3may contain a halogen atom as a substituent. Also, R 1 may be substituted with a substituent such as a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a nitro group, or a benzyl group. [ka] In formula (2), R 4 represents a hydrogen atom, a cycloalkyl group having 3 to 12 carbon atoms, or an alkyl group having 1 to 12 carbon atoms; R 5 and R 6 each independently represents 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.

[0027] In the above formula (1), the arylalkyl group having 7 to 14 carbon atoms is not limited, but examples thereof include a benzyl group, a phenylethyl group, a phenylpropyl group, a naphthylmethyl group, a naphthylethyl group, and a naphthylpropyl group.

[0028] In the above formulas (1) and (2), the aryl group having 6 to 14 carbon atoms is not limited, but examples thereof include a phenyl group, a tolyl group, a xylyl group, a naphthyl group, a biphenyl group, an anthracenyl group, and a phenanthryl group.

[0029] In the above formulas (1) and (2), the alkyl group having 1 to 12 carbon atoms may be linear or branched and is not particularly limited, but examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, a 2-methylbutyl group, an n-pentyl group, a 2-pentyl group, a 3-pentyl group, a 2,2-dimethylpropyl group, an n-hexyl group, a heptyl group, an n-octyl group, a 1,1,3,3-tetramethylbutyl group, a 2-ethylhexyl group, a nonyl group, a decyl group, an undecyl group, and a dodecyl group.

[0030] In the above formula (1), examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0031] In the above formula (1), the alkoxy group having 1 to 6 carbon atoms is not limited, but examples thereof include a methoxy group, an ethoxy group, an n-butoxy group, and a methoxyethoxy group.

[0032] In the above formula (1), examples of the cycloalkyl group having 3 to 12 carbon atoms include, but are not limited to, a cyclopropyl group, a cyclopropylmethyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cyclohexylmethyl group, a trimethylcyclohexyl group, a thujyl group, a norbornyl group, a bornyl group, a norcaryl group, a caryl group, a menthyl group, a norpinyl group, a pinyl group, a 1-adamantyl group, and a 2-adamantyl group.

[0033] Specific examples are given below. Examples of the monomers (N-arylmaleimides, N-aromatic substituted maleimides, etc.) that form the structural unit represented by formula (1) 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)maleimide, N-phenyl ... 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, 1,3,4-triphenyl-1H-pyrrole-2,5-dione, and the like. Among these monomers, N-phenylmaleimide and N-benzylmaleimide are preferred because they have excellent heat resistance and optical properties such as birefringence. These monomers may be used alone or in combination of two or more.

[0034] Examples of the monomer that forms the structural unit represented by 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 thereof include laurylmaleimide, N-cyclopentylmaleimide, N-cyclohexylmaleimide, 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. Among these monomers, N-methylmaleimide, N-ethylmaleimide, N-isopropylmaleimide, and N-cyclohexylmaleimide are preferred because they provide excellent weather resistance to the methacrylic resin, and N-cyclohexylmaleimide is particularly preferred because it has excellent low moisture absorption, which is a requirement for optical materials in recent years. These monomers may be used alone or in combination of two or more.

[0035] In the methacrylic resin in the methacrylic resin composition, it is particularly preferable to use a structural unit represented by formula (1) and a structural unit represented by formula (2) in combination, in order to develop highly controlled birefringence characteristics. The molar ratio (X1 / X2) of the content (X1) of the structural unit represented by formula (1) to the content (X2) of the structural unit represented by formula (2) is preferably more than 0 and not more than 15, more preferably more than 0 and not more than 10. When the molar ratio (X1 / X2) is within this range, the polarizing beam splitter of this embodiment maintains its transparency, does not yellow, and exhibits good heat resistance and good photoelastic properties without impairing environmental resistance.

[0036] The content of the structural units derived from the N-substituted maleimide monomer is preferably in the range of 5 to 40% by mass, and more preferably in the range of 5 to 35% by mass, based on 100% by mass of the methacrylic resin. When the content of the structural units derived from the N-substituted maleimide monomer is within this range, the methacrylic resin exhibits a more sufficient improvement in heat resistance, and also exhibits more favorable improvements in weather resistance, low water absorption, and optical properties. Note that keeping the content of the structural units derived from the N-substituted maleimide monomer to 40% by mass or less is effective in preventing a decrease in the physical properties of the methacrylic resin due to a decrease in the reactivity of the monomer components during the polymerization reaction and an increase in the amount of unreacted remaining monomer. Furthermore, by appropriately adjusting the content of structural units derived from N-substituted maleimide monomers within this range, birefringence caused by orientation or residual stress during molding can be reduced, resulting in a polarizing beam splitter with an average absolute value of in-plane retardation of 10 nm or less. The optimal content of structural units derived from N-substituted maleimide monomers varies depending on the type of N-substituted maleimide. For example, when methyl methacrylate is used as the methacrylic acid 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 ranges of 79 to 83 mass% of structural units derived from methyl methacrylate, 6 to 8 mass% of structural units derived from N-phenylmaleimide, and 11 to 13 mass% of structural units derived from N-cyclohexylmaleimide.

[0037] The methacrylic resin having a structural unit derived from an N-substituted maleimide monomer may contain a structural unit derived from another monomer copolymerizable with the methacrylic acid ester monomer and the N-substituted maleimide monomer, as long as the object of the present invention is not impaired. For example, the other copolymerizable monomers include aromatic vinyls; unsaturated nitriles; acrylic esters having a cyclohexyl group, a benzyl group, or an alkyl group having 1 to 18 carbon atoms; glycidyl compounds; and unsaturated carboxylic acids. Examples of the aromatic vinyl include styrene, α-methylstyrene, and divinylbenzene. Examples of the unsaturated nitrile include acrylonitrile, methacrylonitrile, and ethacrylonitrile. Examples of the acrylic ester include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, and butyl acrylate. Examples of the glycidyl compound include glycidyl (meth)acrylate. Examples of the unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and half-esters or anhydrides of these acids. The structural unit derived from the other copolymerizable monomer may be of only one type, or may be of two or more types.

[0038] The content of structural units derived from these other 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, based on 100% by mass of the methacrylic resin. If the content of the structural units derived from other monomers is within this range, the molding processability and mechanical properties of the resin can be improved without impairing the inherent effect of introducing a ring structure, which is preferable.

[0039] The content of the structural unit derived from the N-substituted maleimide monomer and the content of the structural unit derived from other copolymerizable monomers are as follows: 1 H-NMR measurement and 13It can be determined by C-NMR measurement. 1 H-NMR measurement and 13 C-NMR measurement can be carried out, for example, using CDCl3 or DMSO-d6 as a measurement solvent at a measurement temperature of 40°C.

[0040] --Glutarimide structural unit-- Examples of methacrylic resins having glutarimide structural units include those described in JP 2006-249202 A, JP 2007-009182 A, JP 2007-009191 A, JP 2011-186482 A, and Republished Patent Publication No. 2012 / 114718, and can be formed by the methods described in these publications. The glutarimide structural units constituting the methacrylic resin may be formed after polymerization of the resin. Specifically, the glutarimide structural unit may be represented by the following general formula (3).

[0041] [ka] In the above general formula (3), preferably R 7 and R 8 are each independently a hydrogen atom or a methyl group, and R 9 is a hydrogen atom, a methyl group, a butyl group, or a cyclohexyl group, and more preferably, R 7 is a methyl group, and R 8 is a hydrogen atom, and R 9 is a methyl group. The glutarimide-based structural unit may contain only one type, or may contain multiple types.

[0042] In the methacrylic resin having glutarimide structural units, the content of the glutarimide 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 the glutarimide structural unit is within the above range, a resin having good moldability, heat resistance, and optical properties can be obtained, which is preferable. Furthermore, by appropriately adjusting the content of glutarimide-based structural units within this range, it is possible to reduce birefringence caused by orientation during molding or residual stress, and obtain a polarizing beam splitter with an average absolute value of in-plane retardation of 5 nm or less. 7 ~R 9 The optimum content of glutarimide structural units varies depending on the type of substituent of R. 7 and R 8 is a hydrogen atom, R 9 When is a methyl group, if the content of glutarimide structural units is in the range of 3 to 10 mass %, birefringence caused by orientation or residual stress during molding can be reduced, and a polarizing beam splitter with an average absolute value of in-plane retardation of 10 nm or less can be obtained. The content of glutarimide structural units in the methacrylic resin can be determined using the method described in the aforementioned patent document.

[0043] The methacrylic resin having glutarimide structural units may further contain aromatic vinyl monomer units, if necessary. The aromatic vinyl monomer is not particularly limited, but examples thereof include styrene and α-methylstyrene, with styrene being preferred.

[0044] The content of aromatic vinyl units in the methacrylic resin having glutarimide structural units is not particularly limited, but is preferably 0 to 20% by mass, with the methacrylic resin having glutarimide structural units being 100% by mass. When the content of the aromatic vinyl unit is within the above range, it is possible to achieve both heat resistance and excellent photoelasticity, which is preferable. For example, when a resin is obtained by glutarimidating a methyl methacrylate-styrene copolymer obtained by copolymerizing methyl methacrylate as the methacrylic acid ester monomer and styrene as the aromatic vinyl monomer, by adjusting the ranges of 65 to 90 mass% of structural units derived from methyl methacrylate, 5 to 15 mass% of structural units derived from styrene, and 5 to 20 mass% of glutarimide-based structural units, it is possible to reduce birefringence caused by orientation and residual stress during molding and to obtain a polarizing beam splitter with an average absolute value of in-plane retardation of 10 nm or less.

[0045] --Aromatic vinyl structural unit-- The aromatic vinyl structural unit is not particularly limited, but examples thereof include structural units derived from styrene and α-methylstyrene, with styrene-derived structural units being preferred.

[0046] --Alicyclic vinyl structural unit-- The alicyclic vinyl structural unit can be formed by the methods described in, for example, JP-A Nos. 2006-291184, 2006-291184, 2014-77043, and 2014-77044.

[0047] --Lactone ring structural unit-- Methacrylic resins having lactone ring structural units can be formed by the methods described in, for example, JP-A Nos. 2001-151814, 2004-168882, 2005-146084, 2006-96960, 2006-171464, 2007-63541, 2007-297620, and 2010-180305.

[0048] The lactone ring structural unit constituting the methacrylic resin may be formed after polymerization of the resin. The lactone ring structural unit in this embodiment is preferably a six-membered ring because it has excellent stability of the ring structure. As the 6-membered lactone ring structural unit, for example, a structure represented by the following general formula (4) is particularly preferred.

[0049] [ka]

[0050] In the above general formula (4), R 10 , R 11 and R 12 are each independently a hydrogen atom or an organic residue having 1 to 20 carbon atoms. Examples of organic residues include saturated aliphatic hydrocarbon groups (e.g., alkyl groups) having 1 to 20 carbon atoms, such as a methyl group, an ethyl group, or a propyl group; unsaturated aliphatic hydrocarbon groups (e.g., alkenyl groups) having 2 to 20 carbon atoms, such as an ethenyl group or a propenyl group; aromatic hydrocarbon groups (e.g., aryl groups) having 6 to 20 carbon atoms, such as a phenyl group or a naphthyl group; and groups in which one or more hydrogen atoms in these saturated aliphatic hydrocarbon groups, unsaturated aliphatic hydrocarbon groups, or aromatic hydrocarbon groups have been substituted with at least one group selected from the group consisting of a hydroxy group, a carboxyl group, an ether group, and an ester group.

[0051] The lactone ring structural unit can be formed, for example, by copolymerizing an acrylic acid monomer having a hydroxy group with a methacrylic acid ester monomer such as methyl methacrylate to introduce a hydroxy group and an ester group or a carboxyl group into the molecular chain, and then causing dealcoholization (esterification) or dehydration condensation (hereinafter also referred to as a "cyclization condensation reaction") between the hydroxy group and the ester group or the carboxyl group.

[0052] Examples of the acrylic acid monomer having a hydroxy group used in the polymerization include 2-(hydroxymethyl)acrylic acid, 2-(hydroxyethyl)acrylic acid, alkyl 2-(hydroxymethyl)acrylates (e.g., methyl 2-(hydroxymethyl)acrylate, ethyl 2-(hydroxymethyl)acrylate, isopropyl 2-(hydroxymethyl)acrylate, n-butyl 2-(hydroxymethyl)acrylate, t-butyl 2-(hydroxymethyl)acrylate), alkyl 2-(hydroxyethyl)acrylates, and the like. Preferred are 2-(hydroxymethyl)acrylic acid and alkyl 2-(hydroxymethyl)acrylates, which are monomers having a hydroxyalkyl moiety, and particularly preferred are methyl 2-(hydroxymethyl)acrylate and ethyl 2-(hydroxymethyl)acrylate.

[0053] The content of the lactone ring structural unit in the methacrylic resin having the lactone ring structural unit is preferably 5 to 40 mass %, more preferably 5 to 35 mass %, relative to 100 mass % of the methacrylic resin. When the content of the lactone ring structural unit is within this range, the effects of introducing the ring structure, such as improved solvent resistance and surface hardness, can be achieved while maintaining moldability. Furthermore, by appropriately adjusting the content of the lactone ring structural unit within this range, it is possible to reduce birefringence caused by orientation and residual stress during molding, and to obtain a polarizing beam splitter with an average absolute value of in-plane retardation of 10 nm or less. The content of the lactone ring structure in the methacrylic resin can be determined by the method described in the aforementioned patent document.

[0054] The methacrylic resin having a lactone ring structural unit may have a structural unit derived from another monomer copolymerizable with the above-mentioned methacrylic acid ester monomer and acrylic acid monomer having a hydroxy group. Examples of such copolymerizable other monomers include monomers having a polymerizable double bond, such as styrene, vinyltoluene, α-methylstyrene, α-hydroxymethylstyrene, α-hydroxyethylstyrene, acrylonitrile, methacrylonitrile, methallyl alcohol, ethylene, propylene, 4-methyl-1-pentene, vinyl acetate, 2-hydroxymethyl-1-butene, methyl vinyl ketone, N-vinylpyrrolidone, and N-vinylcarbazole. The copolymer may contain only one type of these other monomers (structural units), or may contain two or more types.

[0055] The content of structural units derived from these other copolymerizable monomers is preferably 0 to 20% by mass relative to 100% by mass of the methacrylic resin, and from the viewpoint of weather resistance, it is more preferably less than 10% by mass, and even more preferably less than 7% by mass. The methacrylic resin in the present embodiment may have only one type of structural unit derived from the other copolymerizable monomer, or may have two or more types.

[0056] -Methacrylic resin manufacturing method- The method for producing the methacrylic resin of this embodiment will be described below. In the method for producing methacrylic resins, the polymerization method can be a batch method, a semi-batch method, or a continuous method. Here, the batch method is a process in which the reaction is initiated and progressed after the entire amount of raw materials is charged into a reactor, and the product is recovered after completion. The semi-batch method is a process in which either the raw materials are charged or the product is recovered simultaneously while the reaction is in progress. Furthermore, the continuous method is a process in which both the raw materials are charged and the product is recovered simultaneously while the reaction is in progress. As a method for producing methacrylic resins, a semi-batch method in which some of the raw materials are charged after the reaction has started is preferred from the viewpoint of precisely controlling the copolymer composition. Although a continuous system can be used, it is preferable not to use it as a method for producing a methacrylic resin for the following reasons. Carrying out a polymerization reaction in a single complete mixing reactor has the advantage of reducing the difference in monomer composition between fractions with different molecular weights in the methacrylic resin, but this tends to have an adverse effect on color tone because a large amount of unreacted monomer remains after polymerization. On the other hand, when a plug flow reactor is used, the amount of unreacted monomer can be reduced, but the difference in monomer composition between fractions with different molecular weights in the methacrylic resin tends to be large. When multiple complete mixing reactors or a complete mixing reactor and a plug flow reactor are combined in series, the amount of unreacted monomer can also be reduced, but the difference in monomer composition between the fractions tends to be large.

[0057] The polymerization method for the methacrylic resin is not particularly limited, but examples thereof include emulsion polymerization, solution polymerization, radical polymerization, anionic polymerization, and cationic polymerization.

[0058] The polymerization solvent is not particularly limited, and examples thereof include 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. Furthermore, alcohols such as methanol, ethanol, and isopropanol may be used in combination as a polymerization solvent to the extent that they do not inhibit the dissolution of the polymerization product during polymerization. The amount of solvent used during polymerization is not particularly limited as long as it allows the polymerization to proceed, does not cause precipitation of the copolymer or the monomers used during production, and can be easily removed. For example, when the total amount of the monomers to be blended is 100 parts by mass, the amount of solvent is preferably 10 to 200 parts by mass, more preferably 25 to 200 parts by mass, even more preferably 50 to 200 parts by mass, and still more preferably 50 to 150 parts by mass.

[0059] As the polymerization initiator, any initiator generally used in radical polymerization can be used, and examples thereof include organic peroxides such as cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, benzoyl peroxide, t-butylperoxyisopropyl carbonate, t-amylperoxy-2-ethylhexanoate, t-amylperoxyisononanoate, and 1,1-di(t-butylperoxy)cyclohexane; and azo compounds such as 2,2'-azobis(isobutyronitrile), 1,1'-azobis(cyclohexanecarbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and dimethyl-2,2'-azobisisobutyrate. These 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 amount of the polymerization initiator added may be 0.01 to 1 part by mass, and preferably 0.05 to 0.5 part by mass, when the total amount of the monomers used in the polymerization is 100 parts by mass.

[0060] As the chain transfer agent, any chain transfer agent used in general radical polymerization can be used, and examples thereof include mercaptan compounds such as n-butyl mercaptan, n-octyl mercaptan, n-decyl mercaptan, n-dodecyl mercaptan, and 2-ethylhexyl thioglycolate; halogen compounds such as carbon tetrachloride, methylene chloride, and bromoform; and unsaturated hydrocarbon compounds such as α-methylstyrene dimer, α-terpinene, dipentene, and terpinolene. 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 there are no particular limitations on the addition stage. The amount of the chain transfer agent added may be 0.01 to 1 part by mass, and preferably 0.05 to 0.5 part by mass, when the total amount of the monomers used in the polymerization is 100 parts by mass.

[0061] The method for recovering a polymer from a polymerization solution obtained by solution polymerization is not particularly limited, and examples thereof include a method in which the polymerization solution is added to an excess amount of a poor solvent, such as a hydrocarbon solvent or an alcohol solvent, in which the polymerization product obtained by polymerization is not soluble, followed by treatment with a homogenizer (emulsification dispersion), and unreacted monomers are separated from the polymerization solution by pretreatment such as liquid-liquid extraction or solid-liquid extraction; or a method in which the polymerization solvent and unreacted monomers are separated via a step called a devolatilization step, and the polymerization product is recovered. Here, the devolatilization step refers to a step of removing volatile components such as the polymerization solvent, residual monomers, and reaction by-products under heated and reduced pressure conditions.

[0062] Examples of equipment used in the devolatilization step include a devolatilizer consisting of a tubular heat exchanger and a devolatilization tank; thin-film evaporators such as Wiblen and Exeba manufactured by Kobelco Environmental Solutions Co., Ltd., and Contra and tilted blade Contra manufactured by Hitachi, Ltd.; and a vented extruder having a residence time and surface area sufficient to exhibit devolatilization performance. A devolatilization step using a devolatilization apparatus that combines two or more of these devices can also be used.

[0063] From the viewpoint of improving the color tone, it is preferable to use a devolatilizer that is mainly composed of a heat exchanger and a reduced pressure vessel and does not have a rotating part in its structure. Specifically, a devolatilization apparatus can be used which comprises a devolatilization tank having a structure in which a heat exchanger is disposed at the top of the tank and a pressure reduction unit is attached to a pressure reduction container having a size sufficient for devolatilization, and a discharge device such as a gear pump for discharging the polymer after devolatilization. In the volatilizing apparatus, the polymerization solution is preheated by being fed to a heated heat exchanger, such as a multi-tube heat exchanger, a plate-fin heat exchanger, or a flat-plate heat exchanger having a flat-plate flow path and a heater, which is disposed above the reduced-pressure vessel, and then fed to a volatilizing tank which is heated and under reduced pressure, to separate and remove the polymerization solvent, unreacted raw material mixture, polymerization by-products, and the copolymer. Use of a volatilizing apparatus having no rotating part as described above is preferred because it allows the production of a methacrylic resin having a good color tone.

[0064] The treatment temperature in the devolatilizer is preferably 150 to 350° C., more preferably 170 to 300° C., and even more preferably 200 to 280° C. By setting the temperature at or above the lower limit temperature, the remaining volatile content can be suppressed, and by setting the temperature at or below the upper limit temperature, coloration and decomposition of the resulting methacrylic resin can be suppressed.

[0065] -Additives- The resin compositions constituting the first resin substrate and the second resin substrate of the present embodiment may contain various additives within the range that does not significantly impair the effects of the present invention. The additives are not particularly limited, and examples thereof include antioxidants, light stabilizers such as hindered amine light stabilizers, ultraviolet absorbers, release agents, thermoplastic resins other than methacrylic resins, softeners / plasticizers such as paraffinic process oil, naphthenic process oil, aromatic process oil, paraffin, organic polysiloxane, and mineral oil, flame retardants, antistatic agents, inorganic fillers such as organic fibers and pigments such as iron oxide, reinforcing agents such as glass fibers, carbon fibers, and metal whiskers, colorants, organic phosphorus compounds such as phosphites, phosphonites, and phosphate esters, and mixtures thereof.

[0066] --Antioxidants-- The resin compositions constituting the first resin substrate and the second resin substrate of this embodiment preferably contain an antioxidant that suppresses deterioration and discoloration during molding or use. Examples of the antioxidant include, but are not limited to, hindered phenol-based antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants. In order to precisely control the distortion and warpage of the surface of the molded article, it is essential that the resin composition of this embodiment be maintained at a high temperature in the mold cavity and allowed to cool for an appropriate period of time. When subjected to a long-term thermal history, the amount of heat stabilizer added must be increased to achieve the desired thermal stability. However, from the viewpoints of suppressing bleed-out of the heat stabilizer and preventing it from sticking to the mold, it is preferable to use multiple types of heat stabilizers in combination. For example, it is preferable to use a hindered phenol-based antioxidant in combination with at least one selected from a phosphorus-based antioxidant and a sulfur-based antioxidant. These antioxidants may be used alone or in combination of two or more.

[0067] Examples of the hindered phenol antioxidant include, but are not limited to, 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, ethylene bis(oxyethylene) bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate], hexamethylene bis[ 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-xylin)methyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 2 ,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazin-2-ylamine)phenol, 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate, 2-tert-butyl-4-methyl-6-(2-hydroxy-3-tert-butyl-5-methylbenzyl)phenyl acrylate, etc. Particularly preferred are 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.

[0068] Furthermore, as the hindered phenol-based antioxidant, a commercially available phenol-based antioxidant may be used. Examples of such commercially available phenol-based antioxidants include, but are not limited to, Irganox 1010 (Irganox 1010: pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], manufactured by BASF), Irganox 1076 (Irganox 1076: pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], manufactured by BASF), and the like. 1076: octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, BASF), Irganox 1330 (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 (Irganox 3114: 1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, BASF) manufactured by ADEKA CORPORATION), Irganox 3125 (Irganox 3125, manufactured by BASF), Adeka STAB AO-60 (pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], manufactured by ADEKA CORPORATION), Adeka STAB AO-80 (3,9-bis{2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane, manufactured by ADEKA CORPORATION), Sumilizer BHT (Sumilizer BHT, manufactured by Sumitomo Chemical), Cyanox 1790 (manufactured by Cytec), Sumilizer GA-80 (manufactured by Sumitomo Chemical), Sumilizer GS (Sumilizer GS: 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate, manufactured by Sumitomo Chemical), Sumilizer GM (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, Adekastab AO-60, Adekastab AO-80, Irganox 1076, Sumilizer GS, etc. are preferred from the viewpoint of the effect of imparting thermal stability to the resin. These may be used alone or in combination of two or more.

[0069] Furthermore, examples of the phosphorus-based antioxidant include, but are not limited to, 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'-diylbisphosphonite, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-t-butyl-4-methyl phenyl)pentaerythritol diphosphite, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, tetrakis(2,4-t-butylphenyl)(1,1-biphenyl)-4,4'-diylbisphosphonite, di-t-butyl-m-cresylphosphonite, 4-[3-[(2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2]dioxaphosphepin)-6-yloxy]propyl]-2-methyl-6-tert-butylphenol, and the like. Furthermore, commercially available phosphorus-based antioxidants may be used as the phosphorus-based antioxidant. Examples of such commercially available phosphorus-based antioxidants include, but are not limited to, Irgafos 168 (Irgafos 168: tris(2,4-di-t-butylphenyl)phosphite, manufactured by BASF), Irgafos 12 (Irgafos 12: tris[2-[[2,4,8,10-tetra-t-butyldibenzo[d,f][1,3,2]dioxaphosphen-6-yl]oxy]ethyl]amine, manufactured by BASF), Irgafos 38 (Irgafos 38: bis(2,4-bis(1,1-dimethylethyl)-6-methylphenyl)ethyl ester phosphorous acid, manufactured by BASF), Adeka STAB 329K (ADK STAB-229K, manufactured by ADEKA), Adeka STAB PEP-36 (ADK STAB PEP-36 (ADEKA), ADK STAB PEP-36A (ADEKA), ADK STAB PEP-8 (ADEKA), ADK STAB HP-10 (ADEKA), ADK STAB HP-10 (ADEKA), ADK STAB 2112 (ADK STAB 2112, ADEKA Corporation), ADK STAB 1178 (ADEKA STAB 1178, ADEKA), ADK STAB 1500 (ADEKA), Sandstab P-EPQ (Clariant), Weston 618 (GE), Weston 619G (GE), Ultranox 626 (GE), Sumilizer GP GP: 4-[3-[(2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2]dioxaphosphepin)-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.), and the like. Among these commercially available phosphorus-based antioxidants, from the viewpoint of the effect of imparting thermal stability to the resin and the effect of using them in combination with various other antioxidants, Irgafos 168, ADK STAB PEP-36, ADK STAB PEP-36A, ADK STAB HP-10, and ADK STAB 1178 are preferred, with ADK STAB PEP-36A and ADK STAB PEP-36 being particularly preferred. These phosphorus-based antioxidants may be used alone or in combination of two or more.

[0070] Furthermore, examples of the sulfur-based antioxidant include, but are not limited to, 2,4-bis(dodecylthiomethyl)-6-methylphenol (Irganox 1726, manufactured by BASF), 2,4-bis(octylthiomethyl)-6-methylphenol (Irganox 1520L, manufactured by BASF), 2,2-bis{[3-(dodecylthio)-1-oxoporopoxy]methyl}propane-1,3-diol, and the like. 2,2-bis{[3-(dodecylthio)-1-oxoporopoxy]methyl}propane-1,3-diylbis[3-dodecylthio]propionate] (ADEKA STAB AO-412S, manufactured by ADEKA Corporation), 2,2-bis{[3-(dodecylthio)-1-oxoporopoxy]methyl}propane-1,3-diylbis[3-dodecylthio]propionate] (CHEMINOX PLS, manufactured by Chemipro Chemical Co., Ltd.), and di(tridecyl) 3,3′-thiodipropionate (AO-503, manufactured by ADEKA Corporation). Among these commercially available sulfur antioxidants, Adekastab AO-412S and Cheminox PLS are preferred from the viewpoints of their effect of imparting thermal stability to the resin, their effect in combination with various antioxidants, and ease of handling. These sulfur-based antioxidants may be used alone or in combination of two or more.

[0071] The content of the antioxidant may be any amount that is effective in improving thermal stability. If the content is excessive, problems such as bleeding out during processing may occur. Therefore, the content is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, even more preferably 1 part by mass or less, still more preferably 0.8 parts by mass or less, still more preferably 0.01 to 0.8 parts by mass, and particularly preferably 0.01 to 0.5 parts by mass, relative to 100 parts by mass of the methacrylic resin.

[0072] --Hindered amine light stabilizers-- The resin composition constituting the first resin substrate and the second resin substrate of this embodiment may contain a hindered amine-based light stabilizer. The hindered amine light stabilizer is not particularly limited, but is preferably a compound containing three or more ring structures. Here, the ring structure is preferably at least one selected from the group consisting of an aromatic ring, an aliphatic ring, an aromatic heterocycle, and a non-aromatic heterocycle, and when one compound has two or more ring structures, they may be the same or different. Examples of the hindered amine light stabilizer include, but are not limited to, bis(1,2,2,6,6-pentamethyl-4-piperidyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butyl malonate, a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidylsebacate, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, N ,N'-Bis(2,2,6,6-tetramethyl-4-piperidyl)-N,N'-diformylhexamethylenediamine, polycondensate of 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, poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethylbutyl)amino] -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 Examples of suitable bis(1-undecanoxy-2,2,6,6-tetramethylpiperidin-4-yl)carbonate include 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate and 2,2,6,6-tetramethyl-4-piperidyl methacrylate. Among these, bis(1,2,2,6,6-pentamethyl-4-piperidyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate, a polycondensate of 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, and 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}], the reaction product of 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 content of the hindered amine light stabilizer may be any amount that is effective in improving light stability, and if the content is excessive, problems such as bleeding out during processing may occur. Therefore, the content is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, still more preferably 0.8% by mass or less, still more preferably 0.01 to 0.8% by mass, and particularly preferably 0.01 to 0.5% by mass, relative to 100% by mass of the methacrylic resin.

[0073] --UV absorber-- The resin compositions constituting the first resin substrate and the second resin substrate of this embodiment may contain an ultraviolet absorber. The ultraviolet absorber is not particularly limited, but is preferably an ultraviolet absorber having a maximum absorption wavelength of 280 to 380 nm, and examples thereof include benzotriazole-based compounds, benzotriazine-based compounds, benzophenone-based compounds, oxybenzophenone-based compounds, benzoate-based compounds, phenol-based compounds, oxazole-based compounds, cyanoacrylate-based compounds, and benzoxazinone-based compounds. These ultraviolet absorbents may be used alone or in combination of two or more.

[0074] As the ultraviolet absorber, benzotriazole-based compounds and benzotriazine-based compounds having a molecular weight of 400 or more are preferred, particularly from the viewpoints of compatibility with the resin and volatility upon heating, and benzotriazine-based compounds are particularly preferred from the viewpoint of suppressing decomposition of the ultraviolet absorber itself due to heating during extrusion processing.

[0075] The content of the ultraviolet absorber is not particularly limited as long as it does not impair heat resistance, moist heat resistance, thermal stability, and moldability and exhibits the effects of the present invention, but 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, relative to 100 parts by mass of the methacrylic resin. Within this range, an excellent balance of ultraviolet absorption performance, moldability, etc. is achieved.

[0076] --Mold release agent-- The resin compositions constituting the first and second resin substrates of this embodiment may contain a release agent, including, but not limited to, fatty acid esters, fatty acid amides, fatty acid metal salts, hydrocarbon-based lubricants, alcohol-based lubricants, polyalkylene glycols, carboxylic acid esters, and hydrocarbon paraffin-based mineral oils. These release agents may be used alone or in combination of two or more.

[0077] The fatty acid ester that can be used as the release agent is not particularly limited, and any of the conventionally known fatty acid esters can be used. Examples of fatty acid esters that can be used include ester compounds of fatty acids having 12 to 32 carbon atoms, such as lauric acid, palmitic acid, heptadecanoic acid, stearic acid, oleic acid, arachic acid, and behenic acid, with monohydric aliphatic alcohols, such as palmityl alcohol, stearyl alcohol, and behenyl alcohol, and polyhydric aliphatic alcohols, such as glycerin, pentaerythritol, dipentaerythritol, and sorbitan; and complex ester compounds of fatty acids, polybasic organic acids, and monohydric aliphatic alcohols or polyhydric aliphatic alcohols. Examples of such fatty acid esters 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. , glycerin monobehenate, glycerin mono-12-hydroxystearate, glycerin di-12-hydroxystearate, glycerin tri-12-hydroxystearate, glycerin diacetomonostearate, glycerin citrate fatty acid ester, pentaerythritol adipate stearate, partially saponified montanic acid ester, pentaerythritol tetrastearate, dipentaerythritol hexastearate, sorbitan tristearate, and the like. These fatty acid esters can be used alone or in combination of two or more. Examples of commercially available products include the Rikemal series, Poem series, Rikestar series, and Rikemaster series manufactured by Riken Vitamin Co., Ltd., and the Excel series, Leodor series, Excelpearl series, and Coconard series manufactured by Kao Corporation, and more specific examples include Rikemal S-100, Rikemal H-100, Poem V-100, Rikemal B-100, Rikemal HC-100, Rikemal S-200, Poem B-200, Rikestar EW-200, Rikestar EW-400, Excel S-95, and Leodor MS-50.

[0078] The content of the release agent may be an amount sufficient to obtain the effect as a release agent, and since an excessive content may cause problems such as bleed-out during processing or poor extrusion due to screw slippage, the content is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, even more preferably 1 part by mass or less, still more preferably 0.8 parts by mass or less, still 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 the methacrylic resin. Addition in the above ranges inhibits the decrease in transparency due to the addition of the release agent and also tends to inhibit poor release during injection molding.

[0079] --Other thermoplastic resins-- The resin compositions constituting the first resin substrate and the second resin substrate of this embodiment may contain thermoplastic resins other than methacrylic resins for the purposes of adjusting birefringence and improving flexibility without impairing the object of the present invention. Other thermoplastic resins include, for example, polyacrylates such as polybutyl acrylate; styrene-based polymers such as polystyrene, styrene-methyl methacrylate copolymer, styrene-butyl acrylate copolymer, styrene-acrylonitrile copolymer, and acrylonitrile-butadiene-styrene block copolymer; and acrylic rubber particles having a three- to four-layer structure, as described in, for example, JP-A-59-202213, JP-A-63-27516, JP-A-51-129449, and JP-A-52-56150; rubbery polymers disclosed in JP-B-60-17406 and JP-A-8-245854; and methacrylic rubber-containing graft copolymer particles obtained by multistage polymerization, as described in WO 2014-002491. Among these, from the viewpoint of obtaining good optical properties and mechanical properties, rubber-containing graft copolymer particles having, on their surface layer, a graft portion made of a composition compatible with a styrene-acrylonitrile copolymer or a methacrylic resin containing a structural unit (X) having a ring structure are preferred. The average particle size of the acrylic rubber particles, methacrylic rubber-containing graft copolymer particles, and rubbery polymer described above is preferably 0.03 to 1 μm, 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.

[0080] The content of the other thermoplastic resin is preferably 0 to 50 parts by mass, and more preferably 0 to 25 parts by mass, based on 100 parts by mass of the methacrylic resin.

[0081] (Method of producing resin composition) The method for producing the resin composition constituting the first resin substrate and the second resin substrate of this embodiment is not particularly limited, as long as it can produce a composition that satisfies the requirements of the present invention. Examples include kneading methods using kneaders such as an extruder, a heated roll, a kneader, a roller mixer, or a Banbury mixer. Among these, kneading using an extruder is preferred in terms of productivity. The kneading temperature may be determined according to the preferred processing temperature of the polymer constituting the methacrylic resin and the other resins to be mixed, and is generally in the range of 140 to 300°C, preferably 180 to 280°C. It is also preferable to provide a vent port in the extruder to reduce volatile content.

[0082] Here, in the resin compositions constituting the first resin substrate and the second resin substrate of this embodiment, the amount of remaining solvent (residual solvent amount) is preferably 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 (excluding alcohols) used during polymerization and the solvent used when redissolving and dissolving the resin obtained by polymerization. Specific examples of the polymerization solvent include aromatic hydrocarbons such as toluene, xylene, ethylbenzene, and isopropylbenzene; ketones such as methyl isobutyl ketone, butyl cellosolve, methyl ethyl ketone, and cyclohexanone; and polar solvents such as dimethylformamide and 2-methylpyrrolidone. Examples of the solvent used for redissolution include toluene, methyl ethyl ketone, and methylene chloride.

[0083] The resin compositions constituting the first resin substrate and the second resin substrate of this embodiment preferably have a residual alcohol amount (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 an alcohol by-produced in the cyclization condensation reaction, and specific examples thereof include aliphatic alcohols such as methanol, ethanol, and isopropanol.

[0084] The amount of the remaining solvent and the amount of the remaining alcohol can be measured by gas chromatography.

[0085] Whichever method is selected, it is preferable to prepare the composition after reducing oxygen and water as much as possible. For example, the dissolved oxygen concentration in the polymerization solution in solution polymerization is preferably less than 300 ppm in the polymerization step, and in a preparation method using an extruder or the like, the oxygen concentration in the extruder is preferably less than 1% by volume, more preferably less than 0.8% by volume. The water 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 is advantageous since it is relatively easy to prepare a composition that satisfies the requirements of the present invention.

[0086] <Method for producing the first resin substrate and the second resin substrate> The method for producing the first resin base material and the second resin base material of this embodiment will be described below. The first resin substrate and the second resin substrate of this embodiment are preferably produced by injection molding the above-described resin composition. For example, they can be produced by injection molding or injection compression molding using an injection molding machine. When producing the first resin substrate or the second resin substrate using an injection molding machine, the temperature setting from the nozzle tip to the center of the injection molding machine cylinder is preferably set to a temperature 120 to 180°C higher than the glass transition temperature (Tg) of the resin composition used. This allows the molten resin to flow sufficiently, enabling molding while suppressing deterioration due to thermal decomposition of the resin. Thermal decomposition of the resin not only adversely affects color tone, transmittance, and haze, but also generates gas during injection molding. The generated gas fills the mold, preventing the gas from being expelled during resin filling, thereby hindering resin filling and reducing mold transfer efficiency. The temperature from the nozzle tip to the center of the injection molding machine cylinder is more preferably set to a temperature 130 to 170°C higher than the glass transition temperature (Tg) of the resin composition used.

[0087] The mold temperature when injection molding the first resin substrate and the second resin substrate of this embodiment is preferably set in the range of (Tg-70)°C to Tg, and more preferably (Tg-50)°C to (Tg-20)°C, relative to the glass transition temperature (Tg) of the resin composition used.

[0088] The injection speed can be appropriately selected depending on the thickness and dimensions of the first and second resin substrates to be obtained, for example, from a range of 10 to 1000 mm / sec. The pressure for holding can be appropriately selected depending on the shapes of the first and second resin substrates to be obtained, for example, from a range of 30 to 150 MPa. Here, the pressure for holding pressure is the pressure maintained by a screw for further feeding the molten resin from the gate after filling the mold with the molten resin.

[0089] The conditions (e.g., mold clamping force and cooling time) for producing the first resin substrate and the second resin substrate of this embodiment by injection molding may be appropriately set and are not particularly limited. The cooling time during injection molding can also be appropriately set, but the longer the better. By cooling slowly, the distortion caused by molding is alleviated by the annealing effect, and birefringence tends to be reduced.

[0090] An annealing step may be performed to relieve residual stress caused by injection molding and reduce the retardation between the first and second resin substrates. The annealing temperature is preferably in the range of (Tg-50)°C to Tg, and more preferably in the range of (Tg-30)°C to (Tg-10)°C, where Tg is the glass transition temperature of the resin composition.

[0091] <Reflective polarizing element> The reflective polarizing element disposed between the first and second resin substrates in the polarizing beam splitter of this embodiment is not particularly limited, and examples include a polarizing element formed by laminating thin films with different birefringence, a structural birefringent wire-grid polarizing element using a subwavelength structure, and an element made of cholesteric liquid crystal that separates right- and left-handed circularly polarized light. Industrially, examples of polarizing elements formed by laminating thin films with different birefringence include multilayer birefringent films APF and DBEF manufactured by 3M. Examples of wire-grid polarizing elements that can be used include a wire-grid reflective polarizing element (WGF (registered trademark) manufactured by Asahi Kasei Corporation) and ProFlux PPL02 (manufactured by Moxtek). Examples of cholesteric liquid crystal plates that can be used include Nipox APCF (manufactured by Nitto Denko Corporation).

[0092] A wire grid reflective polarizing element (WGF (registered trademark), manufactured by Asahi Kasei Corporation) is suitable for the reflective polarizing element. WGF has polarization separation properties that are not dependent on stretching, so its polarization properties are unlikely to be disrupted even when tension is applied to the base film when it is attached to a resin substrate. Furthermore, because there is only one reflective surface involved in polarization separation, it has excellent resolution performance when reflecting an image, unlike polarization separation using multilayer reflection, and therefore can be suitably used in this embodiment.

[0093] A wire grid reflective polarizing element is configured with a holding substrate (described below) (for example, a film is used as the base) and metal wires (for example, aluminum) held on a number of resin protrusions arranged on the surface of the holding substrate at a pitch equal to or less than the wavelength of visible light (approximately 100 nm). Wire grid reflective polarizers have the property of reflecting light that vibrates parallel to the metal wires and transmitting light that vibrates perpendicular to the wires, allowing the polarization direction of reflection / transmission to be selected by changing the orientation of the metal wires.

[0094] The wire grid reflective polarizing element will be described below: Fig. 2 is a schematic cross-sectional view of the wire grid reflective polarizing element.

[0095] The wire grid reflective polarizing element is configured to include a support substrate (base film) 21 and a resin substrate 22 provided on a surface 21a of the support substrate 21 with a bonding layer 29 interposed therebetween. As shown in Fig. 2, a plurality of grid-shaped protrusions 23 are provided on the resin substrate 22. Also, as shown in Fig. 2, the resin substrate 22 has a base layer 24 having a predetermined thickness and the grid-shaped protrusions 23 integrally formed therewith.

[0096] The holding substrate 21 need only be substantially transparent in the target wavelength region, and can be made of, for example, an inorganic material such as glass or a resin material, but it is preferable to use a film (resin material) because a roll process can be used as a manufacturing method and it has high conformability to curved surfaces.

[0097] Resins that can be used for the support substrate 21 include amorphous thermoplastic resins such as polymethyl methacrylate resin, polycarbonate resin, polystyrene resin, cyclic olefin resin (COP), cross-linked polyethylene resin, polyvinyl chloride resin, polyarylate resin, polyphenylene ether resin, modified polyphenylene ether resin, polyetherimide resin, polyethersulfone resin, polysulfone resin, and polyetherketone resin, as well as crystalline thermoplastic resins such as polyethylene terephthalate (PET) resin, polyethylene naphthalate resin, polyethylene resin, polypropylene resin, polybutylene terephthalate resin, aromatic polyester resin, polyacetal resin, and polyamide resin, and also triacetate resin (TAC).Specific examples of suitable resins include TD80UL and ZRD60SL manufactured by Fujifilm Corporation and KC6UA manufactured by Konica Minolta, Inc. Among these, it is preferable to use cyclic olefin resin (COP) because of its low water absorption and high heat resistance.

[0098] The resin substrate 22 can be made of, for example, the same thermoplastic resin as that used for the support substrate 21, or an ultraviolet (UV) curable resin or a thermosetting resin such as an acrylic, epoxy, or urethane resin. The substrate can also be made of a combination of a UV curable resin or a thermosetting resin with the above-mentioned thermoplastic resin or triacetate resin, or of the above-mentioned resin alone. Examples of methods for applying the UV curable resin include a gravure method using a gravure roll, a slot die method, and a knife coating method, as well as an inkjet method and a spray coating method using a potential difference. For curing, a light source emitting UV light or visible light of about 405 nm, which takes into account absorption by an added UV absorber, or a light source emitting an electron beam can also be used.

[0099] The uneven structure having the grid-like protrusions 23 formed on the surface of the resin substrate 22 preferably has a rectangular shape in a cross section perpendicular to the extending direction of the uneven structure. A rectangular shape is formed by repeating recesses and protrusions, and includes trapezoidal, rectangular, and square shapes. Furthermore, when the outline of the uneven structure in a cross section is considered as a function, the area around the inflection point may have a curved portion whose curvature changes smoothly like a parabola, and may also include a shape with a constriction in the protrusion. The shape of the uneven structure makes it easy to form metal wires that are continuous in the vertical direction while being spaced apart on the side surfaces of the convex portions of the uneven structure on the substrate surface and on the bottom surfaces of the concave portions by the oblique deposition method described below. When the metal wires are formed by the oblique deposition method, the metal wires 27 are provided so as to be unevenly distributed on one side surface of the convex portions 23. Therefore, the period of the uneven structure and the period (pitch P) of the metal wires 27 are approximately the same interval.

[0100] The period of the uneven structure (the pitch P between the grid-shaped protrusions 23) (see FIG. 2) is not particularly limited, but is preferably set to a period that can exhibit polarization separation characteristics. Generally, a wire grid polarizer exhibits better polarization separation characteristics over a broader band as the period of the metal wires 27 becomes smaller. When the metal wires 27 are in contact with air (refractive index 1.0), practically sufficient polarization separation characteristics are exhibited by setting the period of the metal wires 27 to 1 / 3 to 1 / 4 of the wavelength of the target light. Therefore, when considering the use of light in the visible light range, the period of the metal wires 27 and the period of the uneven structure of the substrate 22 are preferably 150 nm or less, more preferably 130 nm or less, even more preferably 120 nm or less, and most preferably 100 nm or less. There is no particular lower limit to the period of the metal wires 27 and the period of the uneven structure of the substrate 22, but from the viewpoint of ease of manufacture, it is preferably 50 nm or more, more preferably 60 nm or more, and even more preferably 80 nm or more.

[0101] In this wire grid reflective polarizing element, it is preferable to provide metal wires 27 so that they are unevenly distributed on one side of grid-like convex portions 23 of the concave-convex structure. Therefore, the extending direction of the concave-convex structure and the extending direction of metal wires 27 are substantially parallel. Furthermore, it is sufficient that the concave-convex structure and metal wires 27 extend substantially in a predetermined direction, and it is not necessary for the concave and convex portions of the concave-convex structure and the metal wires to extend strictly parallel to each other.

[0102] 2, a metal layer (metal wire) 27 is formed on at least a part of the surface of each grid-shaped protrusion 23 via a dielectric layer 26. The dielectric layer 26 does not have to be formed. In such a case, the metal layer 27 is formed directly on the surface of the grid-shaped protrusion 23.

[0103] In order to improve the adhesion between the material constituting the resin base material 22 and the metal wire 27, a dielectric layer 26 that has high adhesion to both can be interposed between them. This improves the adhesion between the resin base material 22 and the metal wire 27, thereby preventing the metal wire 27 from peeling off. The dielectric layer 26 may be substantially transparent in the visible region, and examples of suitable dielectrics include oxides, nitrides, halides, and carbides of silicon (Si) alone or in combination (dielectrics in which other elements, elements, or compounds are mixed with a single dielectric), and oxides, nitrides, halides, and carbides of metals such as aluminum (Al), chromium (Cr), yttrium (Y), zirconium (Zr), tantalum (Ta), titanium (Ti), barium (Ba), indium (In), tin (Sn), zinc (Zn), magnesium (Mg), calcium (Ca), cerium (Ce), and copper (Cu), or combinations thereof. The method for laminating the dielectric material is not particularly limited, and suitable examples include physical vapor deposition methods such as vacuum deposition, sputtering, and ion plating.

[0104] The metal constituting the metal layer (metal wire) 27 preferably has high reflectivity in the visible light region and high adhesion to the material constituting the dielectric layer 26. The metal wire 27 can be formed using a conductive material such as aluminum, silver, copper, platinum, gold, or an alloy mainly composed of any of these metals, and is preferably composed of aluminum, silver, or an alloy thereof. From the viewpoint of cost, it is more preferable that the metal wire 27 be composed of aluminum or an alloy thereof. In particular, aluminum is preferable because it can reduce absorption loss in the visible region. There are no limitations on the method for producing the metal wire 27. For example, it can be formed using electron beam lithography or a method using mask patterning by interference exposure and dry etching, or a method using oblique deposition. From the viewpoint of productivity, oblique deposition is preferable.

[0105] The oblique deposition method is a method in which, in a cross section perpendicular to the extension direction of the concave-convex structure (hereinafter abbreviated as "cross-sectional view"), a deposition source is positioned at an angle relative to the perpendicular direction to the surface of the substrate, and a metal is deposited and stacked on the substrate while maintaining a predetermined angle. The preferred range of the deposition angle is determined based on the convex portions of the concave-convex structure and the cross-sectional shape of the metal wire to be fabricated. Generally, a range of 5 to 45 degrees is preferred, and a range of 5 to 35 degrees is more preferred. Furthermore, gradually decreasing or increasing the deposition angle while taking into account the projection effect of the deposited metal during deposition is advantageous for controlling the cross-sectional shape, such as the height, of the metal wire 27. If the surface of the support substrate 22 is curved, deposition may be performed from a direction oblique to the normal direction to the surface of the resin substrate 22. The shape of the deposition source is not limited as long as it can sufficiently deposit the deposited area, and it can be in the form of intermittent dots or continuous lines. When the deposition source is point-like, deposition can be performed from an oblique direction relative to the extending direction of the concave-convex structure, and the spacing between the concave-convex structure appears to be wider, allowing deposition to reach the bottom of the recesses, which is preferable.

[0106] Specifically, the resin substrate 22 has a surface with a concave-convex structure extending generally parallel to one another at a predetermined pitch in a specific direction. The center of the vapor deposition source is positioned at an angle of 5 degrees or more and less than 45 degrees relative to the vertical direction at the center of the region to be vapor deposited on the surface of the resin substrate 22, and the metal wire 27 is formed on the concave-convex structure. More preferably, the center of the vapor deposition source is positioned at an angle of 5 degrees or more and less than 35 degrees relative to the vertical direction at the center of the region to be vapor deposited on the surface of the resin substrate 22. This allows the metal wire 27 to be selectively provided on either side of the convex portions 23 of the concave-convex structure on the surface of the resin substrate 22. When vapor deposition is performed while the substrate is being transported, vapor deposition may be performed so that the center of the region to be vapor deposited and the center of the vapor deposition source at a given moment satisfy the above-described conditions.

[0107] The amount of metal deposition (average thickness) is preferably about 50 to 300 nm. The average thickness here refers to the thickness of the deposited material when it is assumed that the material is deposited on a smooth glass substrate from a direction perpendicular to the glass surface, and is used as a guide for the amount of metal deposition.

[0108] 2, the holding substrate 21 and the resin substrate 22 may be bonded via a bonding layer 29, which may be an adhesive layer or a pressure-sensitive adhesive layer, for the purpose of improving adhesion or adjusting the refractive index. For example, a thin dielectric layer of silica, alumina, or the like may be formed between the holding substrate 21 and the resin substrate 22, or a modified layer may be formed by subjecting the surface 21a of the holding substrate 21 to corona discharge treatment, atmospheric pressure plasma treatment, vacuum plasma treatment, or ultraviolet treatment to impart functional groups or a finely textured shape.

[0109] The thickness of the reflective polarizing element is not particularly limited and may be, for example, about 50 μm to 200 μm, specifically preferably 50 to 150 μm or less, more preferably 50 to 130 μm or less.

[0110] In order to improve the adhesion between the reflective polarizing element and the first and second resin substrates, the reflective polarizing element can be subjected to corona discharge treatment, atmospheric pressure plasma treatment, vacuum plasma treatment, or ultraviolet treatment to form a modified layer that imparts functional groups or a finely textured shape.

[0111] <First adhesive layer and second adhesive layer> The polarizing beam splitter of this embodiment includes a first adhesive layer between the first resin substrate and the reflective polarizing element, and a second adhesive layer between the second resin substrate and the reflective polarizing element. The size and shape of the first adhesive layer and the second adhesive layer are not particularly limited, but from the viewpoint of obtaining a uniform in-plane thickness and sufficient adhesive strength, for example, the average thickness of each is preferably 0.01 to 500 μm, more preferably 0.5 to 100 μm, and even more preferably 1.0 to 10 μm. The first adhesive layer and the second adhesive layer may be the same or different in size and shape. The first adhesive layer may cover the entire adhesive surface (surface facing the reflective polarizing element) of the first resin substrate, or may cover only a portion thereof. Also, the first adhesive layer may cover the entire adhesive surface (surface facing the first resin substrate) of the reflective polarizing element, or may cover only a portion thereof. The second adhesive layer may cover the entire or only a part of the adhesive surface of the second resin substrate (the surface facing the reflective polarizing element). Also, the second adhesive layer may cover the entire or only a part of the adhesive surface of the reflective polarizing element (the surface facing the second resin substrate).

[0112] The first adhesive layer and the second adhesive layer can be made of known adhesives and pressure-sensitive adhesives, and the first adhesive layer and the second adhesive layer can be made of the same material or different materials. It is preferable to use an adhesive because of its high adhesive strength and heat resistance. Examples of adhesives include adhesives such as acrylic resins, epoxy resins, and silicone resins, and the curing system thereof includes photocurable and thermosetting types. The photocurable type is preferred, and among these, ultraviolet curable types are more preferred. By using a photocurable type, damage to the resin substrate due to heat during production is not caused, and product characteristics can be well maintained. Note that it is preferable to use an acrylic resin adhesive because of its good adhesion to the first resin substrate and the second resin substrate made of a methacrylic resin composition.

[0113] Examples of materials for the acrylic resin adhesive include (meth)acrylic monomers, photopolymerization initiators, photosensitizers, and additives.

[0114] Examples of (meth)acrylic monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 4-hydroxycyclohexyl (meth)acrylate, 5-hydroxycyclooctyl (meth)acrylate, 1,3-butanediol (meth)acrylate, 1,4-butanediol (meth)acrylate, 1,6-hexanediol (meth)acrylate, 3-methylpentanediol (meth)acrylate, dicyclopentenyl acrylate, isobornyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-isocyanateethyl (meth)acrylate, and 1,1-bis(acryloyloxymethyl)ethyl isocyanate. These may be used alone or in combination of two or more.

[0115] Examples of the photopolymerization initiator include a benzoin compound, an acetophenone compound, an acylphosphine oxide compound, a titanocene compound, a thioxanthone compound, and an oxime ester compound. Examples of the photosensitizer include amine compounds and quinone compounds. Examples of additives include silane coupling agents such as 3-glycidoxypropyltrimethoxysilane, vinylpropyltrimethoxysilane, and 3-methacryloxypropyltrimethoxysilane, and oligomers such as an ester of a maleic anhydride adduct of an isoprene polymer with 2-hydroxyethyl methacrylate.

[0116] The method for forming the first adhesive layer and the second adhesive layer is not particularly limited, and examples include a method in which an adhesive is applied so as to cover all or part of the adhesive surfaces of the first resin substrate, the second resin substrate, and the reflective polarizing element, and then light is irradiated to harden the adhesive.

[0117] The method for applying the adhesive is not particularly limited, and any conventionally known method can be used, specifically, spraying, spin coating, wire bar coating, dip coating, air knife coating, roll coating, blade coating, inkjet coating, etc.

[0118] Examples of light sources used for light irradiation when curing the adhesive include light sources that emit ultraviolet rays, such as ultra-high pressure mercury lamps, high pressure mercury lamps, carbon arc lamps, xenon arc lamps, and metal halide lamps. The amount of irradiation energy when irradiating ultraviolet rays is 100 to 8000 mJ / cm. 2 is preferred.

[0119] In the polarizing beam splitter of this embodiment, the peeling area ratio of both the first adhesive layer and the second adhesive layer when exposed to an environment at a temperature of 60°C and a relative humidity of 90% for 1000 hours is preferably 15% or less, more preferably 10% or less, and even more preferably 5% or less. If the peeling area ratio of the adhesive layer when exposed to an environment at a temperature of 60°C and a relative humidity of 90% for 1000 hours is within the above range, deterioration of optical performance in a high-temperature and humid environment tends to be further suppressed, and a clearer image tends to be obtained. The peeled area can be measured by the method described in the examples below.

[0120] <Silane coupling agent layer> The polarizing beam splitter of this embodiment is characterized by including a silane coupling agent layer between at least one of the following: between the first resin substrate and the first adhesive layer, between the first adhesive layer and the reflective polarizing element, between the reflective polarizing element and the second adhesive layer, and between the second adhesive layer and the second resin substrate. When a plurality of silane coupling agent layers are provided, they may all be formed of the same type of material, or may be formed of different materials. The polarizing beam splitter of this embodiment is provided with at least one silane coupling agent layer, which allows the resin substrate and adhesive layer to be firmly bonded, suppressing deterioration of optical performance in high-temperature and humid environments and enabling clear images to be obtained.

[0121] The silane coupling agent layer can be formed by chemical vapor deposition of a silane coupling agent on the first resin substrate, the second resin substrate, and / or the reflective polarizing element. For example, a vacuum plasma device is used to supply water, oxygen gas, or the like into a reaction chamber to hydrophilize the surfaces of the first resin substrate, the second resin substrate, and / or the reflective polarizing element, and then the surfaces are reacted with the silane coupling agent to form the silane coupling agent layer.

[0122] Silane coupling agents are compounds containing an organic functional group that reacts with organic substances and a hydrolyzable group (e.g., an alkoxy group) that reacts with inorganic substances. They are used to improve the interaction between organic and inorganic materials at their interfaces. However, when using silane coupling agents to improve interfacial interactions between organic materials, the organic material must react with the hydrolyzable group of the silane coupling agent, which often limits the treatment conditions. For example, Japanese Patent Publication Nos. 4065962 and 5733392 describe examples of treating epoxy resins and cyclic olefin resins with silane coupling agents. However, these methods involve heating the resin substrate at high temperatures and irradiating it with short-wavelength vacuum ultraviolet light, limiting the range of resins to which they can be applied. In particular, methacrylic resin compositions generally have poor heat resistance and are prone to decomposition due to ultraviolet light. Therefore, it is preferable to treat methacrylic resin compositions with silane coupling agents under mild conditions.

[0123] As the silane coupling agent for forming the silane coupling agent layer, known silane coupling agents can be used, but it is preferable to use an alkoxysilane having at least one alkoxy group. The number of alkoxy groups is preferably 2 or 3 (i.e., dialkoxysilane or trialkoxysilane), and those having three alkoxy groups are particularly preferred. The number of carbon atoms in the alkoxy group is preferably 1 to 4, more preferably 1 to 3.

[0124] Specific examples of silane coupling agents that form the silane coupling agent layer include 3-(trimethoxysilyl)propyl methacrylate, 3-[tris(trimethylsilyloxy)silyl]propyl methacrylate, 3-[diethoxy(methyl)silyl]propyl methacrylate, 3-[dimethoxy(methyl)silyl]propyl methacrylate, (triethoxysilyl)methyl methacrylate, 3-[dimethoxy(methyl)silyl]propyl acrylate, 3-(methoxydimethylsilyl)propyl acrylate, 3-(trimethoxysilyl)propyl acrylate, [dimethoxy(methyl)silyl]methyl methacrylate, vinyltrimethoxysilane, triethoxyvinylsilane, dimethylethoxyvinylsilane, allyltrimethoxysilane, allyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, dimethoxymethylvinylsilane, trimethoxy(7-octen-1-yl) )silane, 3-aminopropyltriethoxysilane, trimethoxy[3-(phenylamino)propyl]silane, 3-(2-aminoethylamino)propyltrimethoxysilane, 3-(2-aminoethylamino)propyldimethoxymethylsilane, 3-aminopropyldimethoxymethylsilane, 3-(ethoxydimethylsilyl)propan-1-amine, [3-(6-aminohexylamino)propyl]trimethoxysilane, 3-aminopropyldiethoxymethylsilane, 3-(methylamino)propyltriethoxysilane, 3-aminopropyltrimethoxysilane, trimethoxy[3-(methylamino)propyl]silane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyl(dimethoxy)methylsilane, triethoxy(3-glycidyloxypropyl)silane, diethoxy(3-glycidyloxypropyl)methylsilane, etc. These may be used alone or in combination of two or more. From the viewpoint of good reactivity with the acrylic adhesive, it is preferable to use a silane coupling agent having a (meth)acryloyl group.

[0125] The silane coupling agent layer of this embodiment can be formed by a conventional liquid-phase method or a gas-phase method. For example, the liquid-phase method is a method of forming a silane coupling agent layer by contacting a substrate with an organic solution containing a silane coupling agent for a certain period of time. On the other hand, the gas-phase method is a method of forming a silane coupling agent layer by contacting a substrate with vapor containing a silane coupling agent for a certain period of time without using a solvent. For example, a vacuum plasma device is used to supply water or oxygen gas into the reaction chamber to introduce hydrophilic functional groups onto the substrate surface, which are then reacted with the silane coupling agent to form a silane coupling agent layer. Unlike the liquid-phase method, the gas-phase method does not use a solvent, so damage to the substrate, such as dissolution by the solvent, can be suppressed. Furthermore, forming a silane coupling agent layer by the gas-phase method is preferable because it can reduce the amount of waste liquid and has a low environmental impact.

[0126] The plasma treatment for forming the silane coupling layer can be carried out using a conventionally known treatment method. For example, atmospheric pressure plasma treatment can be used, in which plasma is generated by applying a voltage between a dielectric and a metal electrode facing each other via a space, and the generated plasma is irradiated with a process gas such as oxygen or nitrogen, thereby irradiating the substrate with the plasma. Alternatively, vacuum plasma treatment can be used, in which the substrate is placed between metal electrodes facing each other via a dielectric in a sealed chamber, and the substrate surface is directly exposed to the plasma. Resins such as methacrylic resin compositions, whose molecular chains are easily scissed by plasma irradiation, can be treated with minimal damage to the substrate by using a remote plasma method, such as atmospheric pressure plasma treatment, in which a plasma-containing process gas is irradiated onto the substrate. On the other hand, direct plasma methods, such as vacuum plasma treatment, in which the substrate is directly exposed to plasma, offer higher treatment efficiency and can be performed in a sealed environment, reducing the risk of impurities being introduced during treatment. Furthermore, the vacuum plasma method is preferred for forming the silane coupling agent layer, as it allows the substrate hydrophilization process and the formation of the silane coupling agent layer to be carried out in a single reactor.

[0127] The gas used for the plasma treatment is not particularly limited as long as it is a gas that can introduce hydroxyl groups onto the surface of the substrate to be treated, and conventionally known gases such as nitrogen, argon, oxygen, and water vapor can be used.

[0128] The power consumption during the discharge treatment during the plasma treatment is preferably 60 W·min to 1500 W·min, more preferably 100 W·min to 1000 W·min, and even more preferably 120 W·min to 800 W·min. When the power consumption during the discharge treatment is 60 W·min or more, the hydrophilization treatment of the substrate is sufficiently carried out, and the silane coupling agent layer tends to be efficiently formed. As a result, the durability of the first or second adhesive layer of the polarizing beam splitter tends to be improved in a high-temperature, humid environment. On the other hand, when the power consumption during the discharge treatment is 1500 W·min or less, the formation of an embrittlement layer near the surface due to deterioration of the first resin substrate or the second resin substrate by the plasma treatment is reduced, and the durability of the first or second adhesive layer of the polarizing beam splitter tends to be improved in a high-temperature, humid environment. Therefore, it is preferable to carry out the discharge treatment with a power consumption within the above range.

[0129] The conditions for forming the silane coupling agent layer (for example, the pressure and gas flow rate during the vacuum plasma treatment) may be set appropriately and are not particularly limited.

[0130] The formation of a silane coupling agent layer can be confirmed by known methods such as measuring the contact angle of water before and after the formation of the silane coupling agent layer, X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (TOF-SIMS), infrared spectroscopy, etc. When confirming the presence or absence of a silane coupling agent layer after forming a first or second adhesive layer on the silane coupling agent layer, surface analysis can be performed by exposing the adhesive interface using methods such as mechanical peeling such as polishing or etching, chemical peeling using a solvent, or physical peeling that deteriorates the adhesive by heating or cooling.

[0131] <Method for manufacturing a polarizing beam splitter> The manufacturing method of the polarizing beam splitter of this embodiment is not particularly limited as long as the above-mentioned configuration is obtained. For example, a silane coupling agent layer may be formed on the adhesive surfaces of the first resin substrate, the second resin substrate, and / or the reflective polarizing element according to the above-mentioned method for forming a silane coupling agent layer, and then the first adhesive layer and the second adhesive layer may be formed sequentially according to the above-mentioned method for forming an adhesive layer, i.e., a method in which the first resin substrate and the reflective polarizing element, and the second resin substrate and the reflective polarizing element are sequentially bonded together, may be mentioned.

[0132] <Polarization conversion element> The polarization conversion element of this embodiment is characterized by including the polarization beam splitter of this embodiment described above. Since the polarization conversion element of this embodiment is equipped with the polarization beam splitter of this embodiment, deterioration of optical performance in a high-temperature and humid environment is suppressed, and clear images can be obtained when used as a component of an image display device.

[0133] The polarization conversion element of this embodiment can be produced by a conventionally known method, for example, the method described in JP-A-2012-118430. [Example]

[0134] The present invention will be explained below by way of specific examples and comparative examples, but is not limited to these.

[0135] [Raw materials] The raw materials used in the examples and comparative examples described later are shown below.

[0136] [[Monomers that make up methacrylic resins]] Methyl methacrylate (MMA): manufactured by Asahi Kasei Corporation N-phenylmaleimide (PMI): Nippon Shokubai Co., Ltd. N-Cyclohexylmaleimide (CMI): Nippon Shokubai Co., Ltd. Styrene: Fujifilm Wako Pure Chemical Industries, Ltd. Methyl 2-(hydroxymethyl)acrylate (MHMA): Combi-Blocks

[0137] [[Organic solvents]] Meta-xylene (mXy): Mitsubishi Gas Chemical Company, Ltd. Methyl isobutyrate: manufactured by Kanto Chemical Co., Ltd. Toluene: Fujifilm Wako Pure Chemical Industries, Ltd.

[0138] [[Polymerization initiator]] 1,1-Di(t-butylperoxy)cyclohexane: NOF Corporation t-Amylperoxy-2-ethylhexanoate: "Luperox 575" manufactured by Arkema Yoshitomi Co., Ltd. t-Amyl peroxyisononanoate: Arkema Yoshitomi Co., Ltd.

[0139] [[Chain transfer agent]] n-Octyl mercaptan: Chevron Phillips Chemical Company n-Dodecyl mercaptan: Fujifilm Wako Pure Chemical Industries, Ltd.

[0140] [[Additives]] Pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]: BASF "Irganox 1010" Tris(2,4-di-t-butylphenyl)phosphite: BASF "Irgafos168" Rikemal H-100: manufactured by Riken Vitamin Co., Ltd. Stearyl phosphate / distearyl phosphate mixture: Sakai Chemical Industry Co., Ltd. Monomethylamine: Mitsubishi Gas Chemical Company, Inc.

[0141] The measurement and evaluation methods for each characteristic are described below.

[0142] (1) Measurement of glass transition temperature The glass transition temperature of the methacrylic resin composition was measured in accordance with JIS-K7121. Using a differential scanning calorimeter (Perkin-Lumer Japan, DSC8000) under conditions of a 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 (first 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 heated again under the same heating conditions (second heating). Of the DSC curves drawn during this period, the glass transition temperature (Tg) (°C) was measured as the intersection (midpoint glass transition temperature) of the step-like change part curve during the second heating with a straight line equidistant in the vertical direction from each extended baseline line.

[0143] (2) Analysis of structural units Regarding the methacrylic resin composition, 1 H-NMR measurement and 13 Each structural unit in the methacrylic resin was identified by C-NMR measurement, and its abundance was calculated. 1 H-NMR measurement and 13 The measurement conditions for C-NMR measurement are as follows: Measuring equipment: JEOL Ltd., JNM-ECZ400S Measurement solvent: CDCl3 or d6-DMSO ·Measurement temperature: 40℃

[0144] (3) Measurement of photoelastic coefficient The methacrylic resin composition was pressed into a film using a vacuum compression molding machine to prepare a measurement sample. Specifically, the sample was prepared using a vacuum compression molding machine (manufactured by Shinto Metal Industries, Ltd., SFV-30 model). The resin composition was preheated at 260°C under reduced pressure (approximately 10 kPa) for 10 minutes, compressed at 260°C and approximately 10 MPa for 5 minutes, and then transferred to a cooling compression molding machine for cooling and solidification. The resulting pressed film was aged for at least 24 hours in a constant temperature and humidity chamber adjusted to 23°C and 60% humidity, after which a measurement specimen (approximately 150 μm thick and 6 mm wide) was cut out. The photoelastic coefficient C was measured using a birefringence measuring device described in detail in Polymer Engineering and Science 1999, 39, 2349-2357. R (Pa -1 ) was measured. The film-like test piece was placed in a film tensioning device (manufactured by Imoto Machinery Co., Ltd.) similarly installed in a constant temperature and humidity chamber so that the distance between the chucks was 50 mm. Next, a birefringence measurement device (manufactured by Otsuka Electronics Co., Ltd., RETS-100) was positioned so that the laser light path of the device was located at the center of the film, and the birefringence of the test piece was measured while applying a tensile stress at a strain rate of 50% / min (distance between chucks: 50 mm, chuck movement speed: 5 mm / min). The absolute value of birefringence (|Δn|) and the tensile stress (σ R ) relationship, the slope of the line is calculated by least squares approximation, and the photoelastic coefficient (C R )(Pa -1 ) was calculated. For the calculation, the tensile stress was 2.5 MPa ≤ σ R Data between ≦10 MPa was used. C R =|Δn| / σ R Here, the absolute value of birefringence (|Δn|) is the value shown below. |Δn|=|nx-ny| (nx: refractive index in the stretching direction, ny: refractive index in the in-plane direction perpendicular to the stretching direction)

[0145] (4) Measurement of total light transmittance The total light transmittance was measured using a turbidity meter COH7700 (manufactured by Nippon Denshoku Industries Co., Ltd.) using a molded article with a thickness of 3 mm in accordance with the provisions of JIS K 7361. The molded article was produced by drying pellets of the methacrylic resin composition at 90°C for 12 hours or more, and then using an injection molding machine (manufactured by Sumitomo Heavy Industries, Ltd., SE180EV-A) to prepare a mold with a size of 100 mm × 100 mm × thickness of 3 mm.

[0146] (5) Measurement of melt viscosity Under conditions conforming to JIS-K7199, a twin capillary rheometer (manufactured by ROSAND) was used at a temperature of 270°C and a shear rate of 1000 sec -1 The melt viscosity (Pa·sec) of the methacrylic resin composition was measured using a capillary die with a diameter of 1 mm.

[0147] (6) Measurement of in-plane retardation between the first resin substrate and the second resin substrate The first resin substrate or the second resin substrate was placed on the measurement stage of a PA-300-L (manufactured by Photonic Lattice Co., Ltd.), and the in-plane retardation distribution was measured at a wavelength of 520 nm. The average absolute value of the in-plane retardation (Re) in the measurement area was calculated, and this was used as the measured value of the in-plane retardation (nm). The birefringence value is preferably in a range where the in-plane retardation is 10 nm or less, which is less likely to adversely affect the optical properties. In addition, if the first resin substrate or the second resin substrate reflected light and the phase difference could not be measured accurately, a low-viscosity liquid (contact liquid manufactured by Shimadzu Corporation) that had a refractive index close to that of the methacrylic resin that formed the first resin substrate or the second resin substrate and did not corrode the methacrylic resin was added to a petri dish, and the first resin substrate or the second resin substrate was immersed in it and placed so that the substrate and the liquid surface were flat with no height difference, and the in-plane phase difference distribution at a wavelength of 520 nm was measured in this state.

[0148] (7) Evaluation of image clarity after high-temperature and humidity testing The polarizing beam splitters obtained in the examples and comparative examples were left in an environment of 60°C temperature and 90% relative humidity for 1000 hours (high temperature and humidity test), and then the clarity of the displayed image was evaluated using the evaluation system shown in Figure 1. As shown in Figure 1, the evaluation system was formed by combining a blue LED (peak wavelength: approximately 465 nm) 1, a collimator lens 2, a polarizing beam splitter 3 (comprising a first resin substrate 31, a second resin substrate 32, and a reflective polarizing element 33; the silane coupling agent layer is not shown), a reflective liquid crystal panel (LCOS: Liquid Crystal On Silicon) 4, a projection lens 5, and a screen 6. Light from the blue LED 1 is collimated by the collimator lens 2, enters the polarizing beam splitter 3, passes through the first resin substrate 31, and is split into P-polarized light and S-polarized light by the reflective polarizing element 33. The S-polarized light is reflected 90 degrees by the reflective polarizing element 33 and enters the reflective liquid crystal panel 4. In the reflective liquid crystal panel 4, the incident S-polarized light is converted to P-polarized light and reflected at pixels that receive an ON signal, and is reflected as S-polarized light at pixels that receive an OFF signal, enters the first resin substrate 31, and reaches the reflective polarizing element 33. In the reflective polarizing element 33 , the P-polarized light is transmitted through the second resin base material 32 , and is then magnified by the projection lens 5 and projected onto the screen 6 . A still image displayed on the screen 6 was observed through the simulator, and the clarity of the displayed image was evaluated according to the following evaluation criteria. [Evaluation criteria] Display image clarity A: The displayed image is free of blurring or smearing. B: The displayed image is slightly unclear due to bleeding and blurring, and there is unevenness or a decrease in brightness. However, it is possible to distinguish what is being displayed. C: The displayed image is unclear due to bleeding and blurring, making it impossible to distinguish what is being displayed, and uneven or reduced brightness is observed.

[0149] (8) Measurement of peeled area ratio of adhesive layer The polarizing beam splitters obtained in the examples and comparative examples were exposed to an environment of 60°C and 90% relative humidity for 1000 hours (high-temperature humidification test), and then the adhesive layer was observed at 100x magnification using a digital microscope VHX-7000 (manufactured by Keyence Corporation), and the areas of the normally adhered and peeled portions were measured. When photographing the observed images, the lighting method and photographing conditions were adjusted arbitrarily so that the adhesive layer was in focus and the image was clear. When observing an object with depth to the adhesive layer, photographs were taken while performing depth stacking. The areas of the normally adhered portions and the peeled portions were measured from the photographed images, and the peeled area ratio (%) was calculated. When the area of ​​the normally adhered portions was measured, the peeled area was calculated by subtracting the area of ​​the normally adhered portions from the area of ​​the entire adhesive layer, and the area ratio was calculated.

[0150] (9) Measurement of polarization retention In the experimental system shown in Figure 3, a polarizing beam splitter was used to measure the polarization retention (%). As shown in Figure 3, a light source 41 (a laser light source with a wavelength of 532 nm), a first linear polarizer 42, a second linear polarizer 43, a polarizing beam splitter 40, and a power meter 44 were combined to measure the polarization maintenance of the polarizing beam splitter 40. In Figure 3(a), S-polarized light was emitted from the light source 41, and the amount of light that was reflected by the polarizing beam splitter 40 and then transmitted through the second linear polarizer 43 was measured using the power meter 44. On the other hand, in Figure 3(b), P-polarized light was emitted from the light source 41, and the amount of light that was transmitted through the polarizing beam splitter 40 and then transmitted through the second linear polarizer 43 was measured using the power meter 44. The average value of the polarization maintenance of the S-polarized light and the P-polarized light obtained by the measurement was taken as the value of the polarization maintenance of the polarizing beam splitter 40. The polarization retention (%) of S-polarized light and P-polarized light was calculated from the formula Tp / (Tc+Tp), where Tp (parallel) is the amount of light measured when the second linear polarizer and the first linear polarizer are arranged in parallel, and Tc (cross) is the amount of light measured when the second linear polarizer and the first linear polarizer are arranged in cross. In Fig. 3, the parallel arrangement is when the transmission axes of the second linear polarizer 43 and the first linear polarizer 42 are parallel, and the cross arrangement is when the transmission axes of the second linear polarizer 43 and the first linear polarizer 42 are orthogonal.

[0151] (Preparation of methacrylic resin composition) -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 as a chain transfer agent, and 225.1 kg of meta-xylene (hereinafter referred to as mXy) ​​were weighed and placed in a 1.25 m 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 MMA solution for further addition. The liquid in the reactor was bubbled with nitrogen at a rate of 30 L / min for 1 hour, and the liquid in Tank 1 and Tank 2 was bubbled with nitrogen at a rate of 10 L / min for 30 minutes each to remove dissolved oxygen. Steam was then blown into the jacket to raise the solution temperature in the reactor to 125°C. While stirring at 50 rpm, a polymerization initiator solution (0.457 kg of 1,1-di(t-butylperoxy)cyclohexane in 2.67 kg of mXy) ​​was added at a rate of 1 kg / h to initiate polymerization. During polymerization, the solution temperature in the reactor was controlled at 125±2°C using the temperature control in the jacket. Thirty minutes after the start of polymerization, the rate of addition of the polymerization initiator solution was reduced to 0.25 kg / h, and mXy was added from Tank 1 at a rate of 29.24 kg / h for 3.5 hours. Then, 4 hours after the initiation of polymerization, the rate of addition of the polymerization initiator solution was increased to 0.75 kg / hour, and additional MMA solution was added from Tank 2 at a rate of 95 kg / hour for 2 hours. Further, 6 hours after the start of polymerization, the addition rate of the polymerization initiator solution was reduced to 0.25 kg / hour, and 7 hours after the start of polymerization, the addition was stopped. Eight hours after the start of polymerization, a polymerization solution containing a methacrylic resin was obtained, to which were added 100.261 kg of Irganox 10 and 0.784 kg of Irgafos 168 as antioxidants, and 0.784 kg of Rikemal H-100 as a mold release agent. Next, the obtained polymerization solution was fed to a concentrator consisting of a tubular heat exchanger and a vaporizer preheated to 250°C for devolatilization. The degree of vacuum in the vaporizer was set to 10 to 15 Torr. The resin flowing down the vaporizer was discharged with a screw pump, extruded through a strand die, cooled with water, and pelletized to obtain a methacrylic resin composition A having N-substituted maleimide structural units. The resulting methacrylic resin composition A had a Tg of 133°C and a melt viscosity of 131 Pa·sec. The composition of methacrylic resin composition A determined by NMR was as follows: MMA units: 81 mass %, PMI units: 7 mass %, and CMI units: 12 mass %.

[0152] -Synthesis Example 2 [Methacrylic Resin Composition B]- A monomer composition consisting of 60.000 mol% methyl methacrylate, 39.998 mol% styrene, and 0.002 mol% t-amylperoxy-2-ethylhexanoate as a polymerization initiator was continuously fed into a 10 L incomplete mixing vessel equipped with a helical ribbon impeller at a rate of 1 kg / h. 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 to maintain a constant liquid level in the vessel, and fed to a concentrator consisting of a tubular heat exchanger and a vaporizer for devolatilization. The vacuum in the vaporizer was maintained at 10-15 Torr. The resin flowing down the vaporizer was discharged using a screw pump, extruded through a strand die, water-cooled, pelletized, and introduced into a solvent removal apparatus to obtain pelletized methyl methacrylate-styrene copolymer. The composition of the methyl methacrylate-styrene copolymer determined by NMR was 60% by mass of MMA units and 40% by mass of styrene units. This copolymer was dissolved in methyl isobutyrate to prepare a 10% by weight methyl isobutyrate solution. A 1000 mL autoclave was charged with 500 parts by weight of this 10% by weight methyl isobutyrate solution of the copolymer and 1 part by weight of 10% by weight Pd / C (manufactured by NE Chemcat Corporation) as a hydrogenation catalyst. The mixture was maintained at 200°C under a hydrogen pressure of 9 MPa for 15 hours to hydrogenate the aromatic double bonds in the styrene moieties of the copolymer. The hydrogenation catalyst was removed using a filter, and 0.05 parts by weight of Rikemal H-100 was added to the polymer solution and mixed. The mixture was then fed to a concentrator consisting of a tubular heat exchanger and a vaporizer for devolatilization. The vacuum in the vaporizer was maintained at 10-15 Torr. The resin flowing down the vaporizer was discharged using a gear pump, extruded through a strand die, cooled with water, and pelletized to obtain methacrylic resin composition B with a hydrogenation conversion of 96%. The resulting methacrylic resin composition B had a Tg of 118°C and a melt viscosity of 67 Pa·sec.

[0153] -Synthesis Example 3 [Methacrylic Resin Composition C]- A 200 L reactor equipped with a paddle-type stirrer, a temperature sensor, a cooling tube, and a nitrogen inlet tube was charged with 41.0 kg of methyl methacrylate (MMA), 10.0 kg of methyl 2-(hydroxymethyl)acrylate (manufactured by Combi Bloks), and 50.0 kg of toluene to prepare a raw material solution. While nitrogen was passed through the solution, the solution was stirred and the temperature was raised to 107°C. Separately, an initiator feed solution was prepared by mixing 0.05 kg of 1,1-di(t-butylperoxy)cyclohexane and 0.36 kg of toluene. When the temperature of the raw material solution reached 107°C, feeding of the initiator feed solution was started according to the profiles (1) to (6). (1) 0.0 to 0.5 hours: Feed rate 0.20 kg / hour (2) 0.5 to 1.0 hours: Feed rate 0.10 kg / hour (3) 1.0 to 2.0 hours: Feed rate 0.08 kg / hour (4) 2.0 to 3.0 hours: Feed rate 0.07 kg / hour (5) 3.0 to 4.0 hours: Feed rate 0.028 kg / hour (6) 4.0 to 7.0 hours: Feed rate 0.026 kg / hour After the initiator was fed over a total of 7 hours, the reaction was continued for another 1 hour, and the polymerization reaction was completed over a total of 8 hours. During the polymerization reaction, the internal temperature was controlled at 107±2° C. To the obtained polymer solution, 51 g of a stearyl phosphate / distearyl phosphate mixture was added, and a cyclization condensation reaction was carried out under reflux (about 90 to 110° C.) for 5 hours. The resulting polymerization liquid was subjected to a cyclocondensation reaction and devolatilization treatment using a φ42 mm twin-screw devolatilizing extruder equipped with four front vents and one back vent, at 140 rpm and a resin equivalent of 10 kg / h, to obtain methacrylic resin composition C. The resulting methacrylic resin composition C had a Tg of 129°C and a melt viscosity of 72 Pa sec. The composition of methacrylic resin composition C determined by NMR was 82 mass% MMA units, 17 mass% lactone ring structural units, and 1 mass% MHMA units.

[0154] -Synthesis Example 4 [Methacrylic Resin Composition D]- A 1.25 m3 reactor equipped with a paddle-equipped stirrer, a temperature sensor, a cooling tube, and a nitrogen inlet tube was charged with 550 kg of methyl methacrylate (MMA), 450 kg of meta-xylene, and 0.18 g of n-octyl mercaptan, and dissolved to prepare a raw material solution. Nitrogen was passed through the mixture, and the temperature was raised to 125°C with stirring. Separately, an initiator feed solution was prepared by mixing 0.23 kg of 1,1-di(t-butylperoxy)cyclohexane and 1.82 kg of meta-xylene. When the temperature of the raw material solution reached 127°C, feeding of the initiator feed solution was started according to the profiles (1) to (6). (1) 0.0 to 0.5 hours: Feed rate 1.00 kg / hour (2) 0.5 to 1.0 hours: Feed rate 0.50 kg / hour (3) 1.0 to 2.0 hours: Feed rate 0.42 kg / hour (4) 2.0 to 3.0 hours: Feed rate 0.35 kg / hour (5) 3.0 to 4.0 hours: Feed rate 0.20 kg / hour (6) 4.0 to 7.0 hours: Feed rate 0.13 kg / hour After the initiator was fed over a total of 7 hours, the reaction was continued for another 1 hour, and the polymerization reaction was completed over a total of 8 hours. The resulting polymer solution was extruded using a 42 mm diameter devolatilizing extruder equipped with four front vents and one back vent. The devolatilization treatment was carried out at 140 rpm at a rate of 10 kg / hour in terms of resin amount to obtain resin pellets. Five parts by mass of monomethylamine (40% by mass aqueous monomethylamine solution) per 100 parts by mass of the resulting resin pellets was introduced into a vented twin-screw extruder via a side feeder at a barrel temperature of 250°C, and an imidization reaction was carried out. Excess methylamine and water were removed appropriately from a vent port installed downstream of the extruder, yielding methacrylic resin composition D. The resulting methacrylic resin composition D had a Tg of 122°C and a melt viscosity of 158 Pa sec. The composition of methacrylic resin composition D determined by NMR was 95% by mass of MMA units and 5% by mass of glutarimide structural units.

[0155] Example 1 Methacrylic resin composition A was used as the material for the first resin base material and the second resin base material.

[0156] [Step of preparing first resin substrate and second resin substrate] Using the methacrylic resin composition A obtained in Synthesis Example 1, a first resin substrate and a second resin substrate were produced by injection molding in an injection molding machine (FANUC Corporation, α-S50iA) using a triangular prism mold 15 mm high with a base that was a right-angled isosceles triangle with sides of 12 mm. The first resin substrate and the second resin substrate were produced under the following conditions: resin temperature 245°C, mold temperature 117°C, injection speed 6 mm / s, pressure hold at 95 MPa for 6 seconds, and cooling time 800 seconds. The obtained first resin substrate and second resin substrate were subjected to ultrasonic cleaning with pure water for 5 minutes, air-dried, and then dried in an oven at 80°C for 1 hour.

[0157] [Silane coupling agent layer formation process] In the silane coupling agent layer forming step, a silane coupling agent layer was formed on each adhesive surface of the first resin substrate, the second resin substrate, and the wire grid reflective polarizing element HC12N (manufactured by Asahi Kasei Corporation).

[0158] The formation of the silane coupling agent layer on the first and second resin substrates was performed using a capacitively coupled high-frequency plasma device, followed by plasma treatment. First, the pressure inside the reaction chamber was reduced to 5-10 Pa using a pressure reducing device. Then, water vapor gas was introduced into the chamber to bring the chamber pressure to 100 Pa. Plasma was generated using a 13.56 MHz high-frequency wave and 50 W of power for 3 minutes. Subsequently, 3-(trimethoxysilyl)propyl methacrylate vapor was introduced into the chamber, and the silane coupling agent layer was formed by reacting the 3-(trimethoxysilyl)propyl methacrylate with the adhesive surfaces of the first and second resin substrates. The water contact angles of the first and second resin substrates before and after the formation of the silane coupling agent layer were measured using a contact angle meter DMs-401 (manufactured by Kyowa Interface Science Co., Ltd.). The water contact angles changed before and after the formation of the silane coupling agent layer, confirming the formation of a silane coupling agent layer on the adhesive surfaces of the first and second resin substrates.

[0159] For the wire grid reflective polarizing element, a silane coupling agent layer was formed on both the surface facing the support substrate (support substrate surface) and the surface facing the resin substrate (wire grid surface). First, a capacitively coupled high-frequency plasma device was used to perform plasma treatment on the support substrate side, followed by the formation of a silane coupling agent layer. After reducing the pressure inside the reaction chamber to 5-10 Pa using a pressure reducing device, water vapor gas was introduced into the chamber so that the pressure inside the chamber reached 100 Pa. For plasma generation, water vapor plasma irradiation was performed for 3 minutes at a power of 50 W using a 13.56 MHz high-frequency wave. Subsequently, 3-(trimethoxysilyl)propyl methacrylate vapor was introduced into the chamber, and the silane coupling agent layer was formed by reacting the 3-(trimethoxysilyl)propyl methacrylate with the protective substrate surface of the wire grid reflective polarizing element. The same treatment was also performed on the wire grid surface.

[0160] [Adhesive layer formation process] In the adhesive layer forming process, a first adhesive layer and a second adhesive layer were formed between the silane coupling agent layer on the first resin substrate and the silane coupling agent layer on the wire grid reflective polarizing element, and between the silane coupling agent layer on the second resin substrate and the silane coupling agent layer on the wire grid reflective polarizing element, respectively. First, the adhesive PHOTOBOND300 (manufactured by Sunrise Co., Ltd.) was applied using a dispenser to the silane coupling agent layer on the hypotenuse of the first resin substrate and the silane coupling agent layer on the support substrate side of the wire grid reflective polarizing element, and then the adhesive was applied with a light intensity of 3000 mJ / cm using a built-in UV curing device HLR400 (manufactured by Sen Special Light Sources Co., Ltd.). 2 Next, a second adhesive layer was formed under the same conditions as above on the silane coupling agent layer on the hypotenuse of the second resin substrate and on the silane coupling agent layer on the wire grid surface side of the wire grid reflective polarizing element, thereby producing a cube-shaped polarizing beam splitter.

[0161] Example 2 A polarizing beam splitter was produced under the same conditions as in Example 1, except that the silane coupling agent layer was formed by changing the silane coupling agent from 3-(trimethoxysilyl)propyl methacrylate to trimethoxy(7-octen-1-yl)silane. The evaluation results are shown in Table 1.

[0162] Example 3 Polarizing beam splitters were produced under the same conditions as in Example 1, except that Resin substrate 1 and Resin substrate 2 were produced using the methacrylic resin composition B obtained in Synthesis Example 2 and at a mold temperature of 100° C. The evaluation results are shown in Table 1.

[0163] Example 4 Polarizing beam splitters were produced under the same conditions as in Example 1, except that Resin substrate 1 and Resin substrate 2 were produced using the methacrylic resin composition C obtained in Synthesis Example 3 and at a mold temperature of 110° C. The evaluation results are shown in Table 1.

[0164] Example 5 Polarizing beam splitters were produced under the same conditions as in Example 1, except that Resin substrate 1 and Resin substrate 2 were produced using the methacrylic resin composition D obtained in Synthesis Example 4 and at a mold temperature of 110° C. The evaluation results are shown in Table 1.

[0165] Example 6 A polarizing beam splitter was produced under the same conditions as in Example 1, except that a silane coupling agent layer was not formed on the wire grid surface of the reflective polarizing element. The evaluation results are shown in Table 1.

[0166] Example 7 A polarizing beam splitter was produced under the same conditions as in Example 1, except that a water vapor plasma treatment was performed for 3 minutes at a power of 500 W when forming the silane coupling agent layer on the first resin substrate and the second resin substrate. The evaluation results are shown in Table 1.

[0167] Example 8 A polarizing beam splitter was fabricated under the same conditions as in Example 1, except that the wire grid reflective polarizing element HC12N (manufactured by Asahi Kasei Corporation) was replaced with a wire grid reflective polarizing element HC12A (manufactured by Asahi Kasei Corporation), and a silane coupling agent layer was not formed on the wire grid surface, but a second adhesive layer was formed using the adhesive that had been previously attached to the wire grid reflective polarizing element HC12A. The evaluation results are shown in Table 1.

[0168] Example 9 The adhesive was changed to OG198-54 (manufactured by Epoxy Technology, Inc.), and the light intensity was 3060 mJ / cm 2 A polarizing beam splitter was produced under the same conditions as in Example 1, except that the first and second adhesive layers were formed by UV irradiation at 1000 kJ / cm 2 . The evaluation results are shown in Table 1.

[0169] (Comparative Example 1) Except for not forming the silane coupling agent layer, a polarizing beam splitter was produced under the same conditions as in Example 1. The evaluation results are shown in Table 1.

[0170] (Comparative Example 2) The silane coupling agent layer was not formed, and the adhesive was changed to OG198-54 (manufactured by Epoxy Technology, Inc.). The light intensity was 3060 mJ / cm. 2 A polarizing beam splitter was produced under the same conditions as in Example 1, except that the first and second adhesive layers were formed by UV irradiation at 1000 kJ / cm 2 . The evaluation results are shown in Table 1.

[0171] (Comparative Example 3) Except for not forming the silane coupling agent layer, a polarizing beam splitter was produced under the same conditions as in Example 8. The evaluation results are shown in Table 1.

[0172] [Table 1] [Industrial Applicability]

[0173] The polarizing beam splitter provided by the present invention suppresses deterioration of optical performance in a high-temperature and humid environment and can provide clear images, and therefore can be suitably used as a display component for head-mounted displays, wearable displays, etc. [Explanation of symbols]

[0174] 1: Blue LED 2: Collimator lens 3: Polarizing beam splitter 31: First resin base material 32: Second resin base material 33: Reflective polarizing element 4: Reflective LCD panel (LCOS) 5: Projection lens 6: Screen 20: Wire grid polarizer 21: Holding base material 21a: Surface 22: Resin substrate 22a: Surface 23: Lattice-shaped convex part 24: Base material layer 26: Dielectric layer 27: Metal layer (metal wire) 29: Bonding layer 40: Polarizing beam splitter 41:Light source 42: Power meter 43: First linear polarizer 44: Second linear polarizer

Claims

1. a first resin substrate; a second resin base material facing the first resin base material; a reflective polarizing element disposed between the first resin base material and the second resin base material; a first adhesive layer disposed between the first resin substrate and the reflective polarizing element; a second adhesive layer disposed between the second resin substrate and the reflective polarizing element; A resin polarizing beam splitter, characterized by comprising a silane coupling agent layer disposed between at least one of the following: between the first resin substrate and the first adhesive layer, between the first adhesive layer and the reflective polarizing element, between the reflective polarizing element and the second adhesive layer, and between the second adhesive layer and the second resin substrate.

2. 2. The resin polarizing beam splitter according to claim 1, wherein the resin polarizing beam splitter has a glass transition temperature (Tg) of 115°C to 160°C.

3. The absolute value of the photoelastic coefficient is 10 × 10 －１２ Pa －１ 3. The resin polarizing beam splitter according to claim 1, wherein:

4. 3. The resin polarizing beam splitter according to claim 1, wherein the first resin base material and the second resin base material contain a methacrylic resin.

5. 5. The resin polarizing beam splitter according to claim 4, wherein the methacrylic resin includes a methacrylic resin having a structural unit with a ring structure.

6. 6. The resin polarizing beam splitter according to claim 5, wherein the structural unit comprises at least one structural unit selected from the group consisting of a structural unit derived from an N-substituted maleimide monomer, a glutarimide structural unit, an aromatic vinyl structural unit, an alicyclic vinyl structural unit, and a lactone ring structural unit.

7. 6. The resin polarizing beam splitter according to claim 5, wherein the structural unit comprises a structural unit derived from an N-substituted maleimide monomer.

8. 3. The resin polarizing beam splitter according to claim 1, wherein the reflective polarizing element comprises a cyclic olefin resin.

9. 3. The resin polarizing beam splitter according to claim 1, wherein the first adhesive layer and / or the second adhesive layer contains a photo-curable acrylic adhesive.

10. A polarization conversion element comprising the resin polarization beam splitter according to claim 1 or 2.

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