Optical functional films, optical laminates, functional glass, and head-up display systems for head-up displays

Abstract

The present invention aims to provide an optical functional film, optical laminate, functional glass, and head-up display system that can suppress the occurrence of double images at low cost and have excellent interlayer adhesion after high-temperature processing. [Solution] An optical functional film in which a phase difference layer and a transparent substrate are bonded together by an adhesive layer, The adhesive layer contains (A) a bifunctional (meth)acrylate, (B) a nitrogen-containing monofunctional vinyl monomer, and (C) a hydroxyl-containing monofunctional (meth)acrylic monomer. An optical functional film for a head-up display, wherein the (A) bifunctional (meth)acrylate is contained in an amount of 0.2 mol% to 6 mol% of the total acrylate components.

Description

[Technical Field]

[0001] The present invention relates to optically functional films, optical laminates, and functional glass suitable for application, for example, to head-up displays, and also to head-up displays using these. [Background technology]

[0002] Navigation systems, head-up displays (hereinafter also referred to as "HUDs"), and the like are used as methods to display information to drivers of automobiles, aircraft, etc. A HUD is a system that projects images from an image projection means such as a liquid crystal display (hereinafter also referred to as "LCD") onto, for example, the windshield of an automobile.

[0003] Light emitted from the image display device is reflected by a reflector, then reflected again by the windshield, and finally reaches the observer. The observer is viewing the image projected onto the windshield, but the image appears to be located at a position further away from the windshield. With this method, the driver can obtain various information with little to no movement of their gaze while keeping their eyes fixed on the road ahead on the windshield, making it safer than conventional car navigation systems that required shifting one's gaze.

[0004] In HUD systems, the displayed information is projected onto the actual view seen through the windshield. However, because the display light is reflected by both the interior and exterior surfaces of the windshield, the reflected image becomes a double image, making the displayed information difficult to see.

[0005] To address this problem, it is known that the issue of reflected images becoming double images can be improved by using a phase difference element that can change the polarization direction by 90° in an automobile windshield. For example, Patent Document 1 discloses that when S-polarized display light is incident at a Brewster angle on an automobile windshield equipped with a film-like photorotator, a portion of the S-polarized light is reflected at the surface of the windshield on the inside of the vehicle, the S-polarized light transmitted through that surface is converted to P-polarized light by the photorotator, and then all of the P-polarized light is emitted outside the vehicle at the surface of the windshield on the outside of the vehicle to prevent double images.

[0006] Another known method for suppressing double images involves using a light-controlled film, which consists of a circularly polarized reflective film made from a cholesteric liquid crystal layer sandwiched between two quarter-wave plates, to incident P-polarized light (Patent Document 2). In this technique, the incident linearly polarized light is converted to circularly polarized light by the quarter-wave plates, and the circularly polarized light converted by the light-reflective film made from a cholesteric liquid crystal layer is reflected, making it visible to the observer. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 6-40271 [Patent Document 2] Re-tabled publication 2016 / 056617 [Overview of the project] [Problems that the invention aims to solve]

[0008] These optical films are expensive due to the large number of optical functional layers, and when sandwiched between glass with an interlayer such as polyvinyl butyral and pressed at high temperatures of 120°C or higher, they can develop wrinkles and undulations in the film, and problems such as delamination can occur during impact resistance tests of laminated glass, which can impair the aesthetics and visibility of the windshield.

[0009] Therefore, the present invention aims to provide an optical functional film, optical laminate, functional glass, and head-up display system that can suppress the occurrence of double images at low cost and have excellent interlayer adhesion after high-temperature processing. [Means for solving the problem]

[0010] As a result of diligent research to solve the above problems, the inventors of the present invention have found that in an optical functional film in which a phase difference layer and two transparent substrates are bonded together with an adhesive layer, the ratio of the difunctional components of the adhesive layer is within a certain range, thereby achieving excellent results and completing the present invention.

[0011] In other words, the present invention relates to the following [1] to

[13] . [1] An optical functional film in which a phase difference layer and a transparent substrate are bonded together by an adhesive layer, The adhesive layer contains (A) a bifunctional (meth)acrylate, (B) a nitrogen-containing monofunctional vinyl monomer, and (C) a hydroxyl-containing monofunctional (meth)acrylic monomer. An optical functional film for head-up displays, containing the aforementioned (A) bifunctional (meth)acrylate in an amount of 0.2 mol% to 6 mol% of the total acrylate components. [2] The optical functional film for a head-up display according to item [1] above, comprising (B) nitrogen-containing monofunctional vinyl monomer in an amount of 10% by mass or more relative to the total mass of the adhesive layer. [3] The optical functional film for a head-up display according to the preceding paragraph [1], wherein the (B) nitrogen-containing monofunctional vinyl monomer is a nitrogen-containing monofunctional (meth)acrylamide monomer. [4] The optical functional film for a head-up display according to the previous item [3], wherein the nitrogen-containing monofunctional (meth)acrylamide monomer is at least one selected from the group consisting of (meth)acrylamide, N-alkyl (meth)acrylamide, N,N-dialkyl (meth)acrylamide, N-hydroxyalkyl (meth)acrylamide, 3-(meth)acryloyl-2-oxazolidinone, 4-(meth)acryloylmorpholine, and N-(meth)acryloylpiperidine. [5] The optical functional film for a head-up display according to the previous item [1], wherein the nitrogen-containing monofunctional vinyl monomer is a nitrogen-containing heterocyclic monofunctional vinyl monomer. [6] The optical functional film for a head-up display according to the previous item [5], wherein the nitrogen-containing heterocyclic monofunctional vinyl monomer is at least one selected from the group consisting of N-vinyl-2-pyrrolidone, vinylpyridine, N-vinylcarbazole, N-(meth)acryloylpyrrolidine, 3-(meth)acryloyl-2-oxazolidinone, 4-(meth)acryloylmorpholine, and N-(meth)acryloylpiperidine. [7] The optical functional film for a head-up display according to the previous item [1], wherein the (C) hydroxyl group-containing monofunctional (meth)acrylic monomer is contained in an amount of 20% by mass or more based on the total mass of the adhesive layer. [8] The optical functional film for a head-up display according to the previous item [1], wherein the retardation layer is a polymerizable liquid crystal layer having a polymerizable liquid crystal compound. [9] The optical functional film for a head-up display according to the previous item [1], wherein the retardation layer is a half-wave plate.

[10] An optical laminate for a head-up display, comprising the optical functional film for a head-up display according to any one of the previous items [1] to [9] and an intermediate film.

[11] The functional glass for a head-up display, comprising the optical functional film for a head-up display according to any one of the preceding items [1] to [9], or the optical laminate for a head-up display according to the preceding item

[10] , between two glass plates.

[12] A head-up display system, comprising a display device and the functional glass for a head-up display according to the preceding item

[11] as a display medium.

[13] The head-up display system according to the preceding item

[12] , wherein the light emitted from the display device is S-polarized light. [Effects of the Invention]

[0012] Since the optical functional film of the present invention has polarization conversion ability when a virtual image is projected onto the front glass, in a head-up system using this film, the generation of double images of the display medium can be suppressed, and the viewer can reduce stress. Furthermore, since the optical functional film of the present invention has good interlayer adhesion after laminated glass processing at a high temperature of 120 °C or higher, it also has excellent appearance and visibility of the front glass. [Brief Description of the Drawings]

[0013] [Figure 1] It is a schematic diagram showing an embodiment of a head-up display system according to the present invention. [Figure 2] It is a schematic diagram showing another embodiment of a head-up display system according to the present invention. [Figure 3] It is a side cross-sectional view showing an embodiment of an optical functional film for a head-up display according to the present invention. [Figure 4] It is a side cross-sectional view showing an embodiment of an optical laminate for a head-up display according to the present invention. [Figure 5] It is a side cross-sectional view showing an embodiment of the functional glass for a head-up display according to the present invention. [Modes for Carrying Out the Invention]

[0014] Embodiments according to the present invention will be described below with reference to the drawings. Note that the embodiments described below are merely examples of some representative embodiments of the present invention, and various modifications can be made within the scope of the present invention. Furthermore, in the following, the expression "for head-up displays" may be omitted, and the terms optical functional film, optical laminate, and functional glass may be used instead. Also, terms such as "(meth)acryloyl" and "(meth)acrylate" mean "acryloyl" or "methacryloyl" and "acrylate" or "methacrylate," respectively. Additionally, "head-up displays" are sometimes referred to as HUDs, and the film used in the phase difference layer is sometimes called a phase difference film.

[0015] [Optical Functional Film] The optical functional film of the present invention is characterized in that a phase difference layer and a transparent substrate are bonded together by an adhesive layer, the adhesive layer contains (A) a bifunctional (meth)acrylate, (B) a nitrogen-containing monofunctional vinyl monomer, and (C) a hydroxyl group-containing monofunctional (meth)acrylic monomer, and the (A) bifunctional (meth)acrylate is contained in an amount of 0.2 mol% to 6 mol% of the total acrylate components.

[0016] [Phase difference layer] The phase difference layer in the optical functional film of the present invention is a layer that has the function of changing the polarization axis of incident light, and examples include a half-wave plate, a quarter-wave plate, a laminate of a half-wave plate and a circularly polarized reflective layer, a laminate of a quarter-wave plate and a circularly polarized reflective layer, and other layers having any arbitrary phase difference. A half-wave plate is preferred.

[0017] <1 / 2 wavelength plate> When a half-wave plate is used as the phase difference layer, the half-wave plate is a phase difference element that has the function of converting P-polarized light to S-polarized light, or S-polarized light to P-polarized light, that is, converting the polarization axis. For example, it can be obtained by uniaxially stretching a film made of polycarbonate or cycloolefin polymer so that the phase difference is half the wavelength, or by aligning a horizontally oriented polymerizable liquid crystal to a thickness such that the phase difference is half the wavelength. Generally, a half-wave plate using horizontally oriented polymerizable liquid crystal consists of a polymerizable liquid crystal layer that has the effect of changing the polarization axis, and a support substrate to which a coating liquid that forms the polymerizable liquid crystal layer is applied. However, the support substrate is not an essential component of the optical functional film of the present invention, and the polymerizable liquid crystal layer can also be transferred to other substrates (e.g., interlayers or glass plates) for use. The upper limit of the thickness of such a half-wave plate is preferably 10 μm or less, and more preferably 5 μm or less, from the viewpoint of liquid crystal orientation. On the other hand, the lower limit of the thickness of the half-wave plate is preferably 0.3 μm or more, and more preferably 0.5 μm or more, from the viewpoint of liquid crystal polymerizability. When light is incident on the main surface of the half-wave plate from an oblique position, the phase difference may change depending on the angle of incidence of the light. In such cases, in order to more precisely match the phase difference, for example, by using a phase difference element with an adjusted refractive index, the change in phase difference with respect to the angle of incidence can be suppressed. For example, when the refractive index in the direction of the slow axis within the plane of the phase difference element is nx, the refractive index in the direction perpendicular to nx within the plane of the phase difference element is ny, and the refractive index in the thickness direction of the phase difference element is nz, the coefficient Nz shown in the following equation (1) is controlled to be preferably 0.3 or more and 1.0 or less, more preferably 0.5 or more and 0.8 or less.

[0018]

number

[0019] While the wavelength dispersion of the half-wave plate described above is not particularly limited as long as it is suitable for head-up display applications, it is desirable to have inverse wavelength dispersion in order to accurately convert polarization over a wide wavelength range in the visible light region. Generally, polymers exhibit normal dispersion, where the absolute value of birefringence is larger on the shorter wavelength side. However, inverse wavelength dispersion can be obtained by controlling the birefringence Δn value for each wavelength of visible light, thereby obtaining a liquid crystal compound that exhibits greater birefringence on the longer wavelength side. Inverse wavelength dispersion can also be obtained by stacking multiple phase difference plates with appropriate phase difference values ​​according to the wavelength dispersion characteristics of the compound, using an appropriate combination of slow axes.

[0020] When the half-wave plate includes a polymerizable liquid crystal layer, the liquid crystal composition constituting the polymerizable liquid crystal layer is coated onto a support substrate. When the half-wave plate is used in a HUD, such a support substrate is preferably transparent in the visible light region in order to maintain the visibility of the displayed image. Specifically, the visible light transmittance at wavelengths of 380 to 780 nm should be 50% or more, preferably 70% or more, and more preferably 85% or more. The support substrate may also be colored, but it is preferable that it be uncolored or lightly colored. Furthermore, the refractive index of the support substrate is preferably 1.2 to 2.0, and more preferably 1.4 to 1.8. The thickness of the support substrate can be appropriately selected depending on the application, preferably 5 μm to 1000 μm, more preferably 10 μm to 250 μm, and particularly preferably 15 μm to 150 μm.

[0021] Examples of support substrates include cellulose acetate-based triacetylcellulose (TAC), acrylic, polycarbonate, polyvinyl chloride, polyolefin, and polyethylene terephthalate (PET). Among these, triacetylcellulose (TAC), polyolefin, and acrylic, which have low birefringence, are preferred. From the viewpoint of optical properties, a thin film thickness of the support substrate is preferred, but if it is too thin, the strength decreases and the processability is poor. An appropriate film thickness is 5 μm to 100 μm, preferably 10 μm to 80 μm, and more preferably 15 μm to 70 μm. Furthermore, the in-plane phase difference of the support substrate is preferably within ±60 nm, and more preferably within ±10 nm, from the viewpoint of optical properties. In addition, the phase difference in the thickness direction of the support substrate is also preferably within ±60 nm, and more preferably within ±10 nm, from the viewpoint of optical properties.

[0022] Next, a method for producing a half-wave plate using the above-mentioned nematic liquid crystal monomer having polymerizable groups will be described. In such a method, for example, the nematic liquid crystal monomer having polymerizable groups is dissolved in a solvent, and then a photopolymerization initiator is added. The solvent is not particularly limited as long as it can dissolve the liquid crystal monomer to be used, but examples include cyclopentanone, toluene, methyl ethyl ketone, methyl isobutyl ketone, etc., with cyclopentanone and toluene being preferred. After that, this solution is applied to a plastic substrate such as a PET film or TAC film to be used as a support substrate so as to be as uniform in thickness as possible, and the solution is removed by heating, and the substrate is left for a certain period of time under temperature conditions that cause the liquid crystals to align on the support substrate. At this time, the orientation of the liquid crystals can be made more uniform by performing an orientation treatment on the surface of the plastic film before application, such as rubbing in the desired orientation direction, or by forming a photo-alignment material (hereinafter referred to as an alignment film coating solution) on the surface of the plastic film that exhibits photo-alignment properties when exposed to polarized light and then irradiating it with polarized light. This makes it possible to control the slow axis of the half-wave plate to a desired angle and reduce the haze value of the half-wave plate. Then, while maintaining this orientation, the nematic liquid crystal monomer is irradiated with ultraviolet light using a high-pressure mercury lamp or the like to fix the orientation of the liquid crystal, thereby obtaining a half-wave plate having the desired slow axis.

[0023] The main role of a half-wave plate is to convert S-polarized or P-polarized light that is transmitted without being reflected at the surface into P-polarized or S-polarized light. This reduces reflection from the support substrate located on the outside, making it possible to suppress double images.

[0024] <1 / 4 wavelength plate> A quarter-wave plate can also be used as the phase difference layer. A quarter-wave plate is a phase difference element that has the function of converting circularly polarized light to linearly polarized light. For example, it can be obtained by uniaxially stretching a film made of polycarbonate or cycloolefin polymer so that the phase difference is 1 / 4 of the wavelength, or by oriented a horizontally oriented polymerizable liquid crystal to a thickness such that the phase difference is 1 / 4 of the wavelength. In addition, it is preferable that the quarter-wave plate also includes a polymerizable liquid crystal layer, similar to the half-wave plate. In such a case, the quarter-wave plate is composed of a polymerizable liquid crystal layer that has the effect of converting the polarization axis, and a support substrate to which a coating liquid that forms the polymerizable liquid crystal layer is applied. The polymerizable liquid crystal layer and the support substrate can be made of the same materials as the nematic liquid crystal monomer and support substrate used in the half-wave plate described above. When the phase difference shift due to wavelength dispersion is large when using a quarter-wave plate, a phase difference element called a broadband quarter-wave plate may be used. A broadband quarter-wave plate is a phase difference element in which the wavelength dependence of the phase difference is reduced. Examples include a phase difference element in which a half-wave plate and a quarter-wave plate with the same wavelength dispersion are stacked so that the angle between their respective slow axes is 60°, and a polycarbonate-based phase difference element with reduced wavelength dependence of the phase difference (Teijin Corporation: PureAce WR-S). Furthermore, in cases where the angle of incidence of light is oblique to the quarter-wave plate, such as in a HUD, the phase difference may change depending on the angle of incidence of the light, depending on the phase difference element. In such cases, as a method to more precisely match the phase difference, for example, by using a phase difference element with an adjusted refractive index, the change in phase difference due to the angle of incidence can be suppressed. As an example of this, when the refractive index in the direction of the slow axis within the plane of the phase difference element is nx, the refractive index in the direction perpendicular to nx within the plane of the phase difference element is ny, and the refractive index in the thickness direction of the phase difference element is nz, the coefficient Nz shown in equation (1) above is preferably controlled to be 0.3 or more and 1.0 or less, more preferably 0.5 or more and 0.8 or less. The upper limit of the thickness of the quarter-wave plate is preferably 10 μm or less, and more preferably 5 μm or less, from the viewpoint of liquid crystal orientation. On the other hand, the lower limit of the thickness of the quarter-wave plate is preferably 0.3 μm or more, and more preferably 0.5 μm or more. Furthermore, the upper limit of the thickness of the circularly polarized reflective layer is preferably 10 μm or less, and more preferably 5 μm or less, from the viewpoint of liquid crystal orientation. On the other hand, the lower limit of the thickness of the circularly polarized reflective layer is preferably 0.3 μm or more, and more preferably 0.5 μm or more, from the viewpoint of liquid crystal polymerization.

[0025] The half-wave plate or quarter-wave plate used as a phase difference layer preferably contains a polymerizable liquid crystal layer having a polymerizable liquid crystal compound. A polymerizable liquid crystal compound is a nematic liquid crystal monomer that has polymerizable groups in its molecule and exhibits liquid crystallinity within a certain temperature or concentration range. Examples of polymerizable groups include (meth)acryloyl groups, vinyl groups, chalconyl groups, cinnamoyl groups, and epoxy groups. Furthermore, for the polymerizable liquid crystal to exhibit liquid crystallinity, it is preferable that it contains a mesogenic group in its molecule. A mesogenic group refers to a rod-shaped or plate-shaped substituent such as a biphenyl group, terphenyl group, (poly)benzoate phenyl ester group, (poly)ether group, benzylideneaniline group, or acenaphthoquinoxaline group, or a disc-shaped substituent such as a triphenylene group, phthalocyanine group, or azacrown group, that is, a group that has the ability to induce liquid crystal phase behavior. Liquid crystal compounds having rod-shaped or plate-shaped substituents are known in the art as calamistic liquid crystals. Examples of nematic liquid crystal monomers having such polymerizable groups include polymerizable liquid crystals described in Japanese Patent Publication No. 2003-315556 and Japanese Patent Publication No. 2004-29824, as well as polymerizable liquid crystals such as the PALIOCOLOR series (manufactured by BASF) and the RMM series (manufactured by Merck). These nematic liquid crystal monomers having polymerizable groups may be used individually or in combination.

[0026] Furthermore, it is possible to add polymerizable compounds that do not possess liquid crystalline properties but can react with nematic liquid crystal monomers having polymerizable groups. Examples of such compounds include UV-curable resins. Examples of UV-curable resins include dipentaerythritol hexa(meth)acrylate, reaction products of dipentaerythritol penta(meth)acrylate and 1,6-hexamethylene-di-isocyanate, reaction products of isocyanuric ring-containing triisocyanate and pentaerythritol tri(meth)acrylate, reaction products of pentaerythritol tri(meth)acrylate and isophorone-di-isocyanate, dipentaerythritol penta(meth)acrylate, dipentaerythritol tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, tris(acryloxyethyl) isocyanurate, and tris(methacryloxyethyl) (Tyl) isocyanurate, reaction product of glycerol triglycidyl ether and (meth)acrylic acid, caprolactone-modified tris(acryloxyethyl) isocyanurate, reaction product of trimethylolpropane triglycidyl ether and (meth)acrylic acid, triglycerol-di-(meth)acrylate, reaction product of propylene glycol-diglycidyl ether and (meth)acrylic acid, polypropylene glycol-di-(meth)acrylate, tripropylene glycol-di-(meth)acrylate, polyethylene glycol-di-(meth)acrylate, tetraethylene glycol-di-(meth)acrylate, triethylene glycol-di-(meth)acrylate, pentaerythritol-di-(meth)acrylate, reaction product of 1,6-hexanediol-diglycidyl ether and (meth)acrylic acid, 1,6-Hexanediol-di-(meth)acrylate, glycerol-di-(meth)acrylate, reaction product of ethylene glycol-di-glycidyl ether and (meth)acrylic acid, reaction product of diethylene glycol-di-glycidyl ether and (meth)acrylic acid, bis(acryloxyethyl)hydroxyethyl isocyanurate, bis(methacryloxyethyl)hydroxyethyl isocyanurate, reaction product of bisphenol A-di-glycidyl ether and (meth)acrylic acid, tetrahydrofurfuryl(meth)acrylate, caprolactone-modified tetrahydrofurfuryl(meth)acrylate, 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, polypropylene glycol(meth)acrylate, polyethylene glycol(meth)acrylate, phenoxyhydroxypropyl Examples include pyr(meth)acrylate, acryloylmorpholine, methoxypolyethylene glycol(meth)acrylate, methoxytetraethylene glycol(meth)acrylate, methoxytriethylene glycol(meth)acrylate, methoxyethylene glycol(meth)acrylate, methoxyethyl(meth)acrylate, glycidyl(meth)acrylate, glycerol(meth)acrylate, ethyl carbitol(meth)acrylate, 2-ethoxyethyl(meth)acrylate, N,N-dimethylaminoethyl(meth)acrylate, 2-cyanoethyl(meth)acrylate, reaction products of butyl glycidyl ether and (meth)acrylic acid, butoxytriethylene glycol(meth)acrylate, and butanediol mono(meth)acrylate, which may be used individually or in combination. These non-crystalline UV-curable resins must be added in an amount that does not cause the composition containing the nematic liquid crystal monomer to lose its crystalline properties. Preferably, the amount is 0.1 parts by mass to 20 parts by mass, more preferably 1.0 part by mass to 10 parts by mass, per 100 parts by mass of the polymerizable nematic liquid crystal monomer.

[0027] When the nematic liquid crystal monomer having polymerizable groups and the polymerizable compound that does not have liquid crystallinity are UV-curable, a photopolymerization initiator is added to cure the composition containing them by ultraviolet light. Examples of photopolymerization initiators include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1 (Omnirad 907, IGM Resins BV), 1-hydroxycyclohexylphenyl ketone (Omnirad 184, IGM Resins BV), 4-(2-hydroxyethoxy)-phenyl(2-hydroxy-2-propyl)ketone (Omnirad 2959, IGM Resins BV), 1-(4-dodecylphenyl)-2-hydroxy-2-methylpropane-1-one (Darocure 953, Merck), 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one (Darocure 1116, Merck), and 2-hydroxy-2-methyl-1-phenylpropane-1-one (Omnirad, IGM Resins BV). Acetophenone compounds such as 1173) and diethoxyacetophenone; benzoin compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether and 2,2-dimethoxy-2-phenylacetophenone (BASF Irgacure 651); benzoylbenzoic acid, benzoylbenzoate methyl, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 3,3'-dimethyl-4-methoxybenzophenone (Nippon Chemical Co., Ltd.) Examples include benzophenone compounds such as Kayacure MBP (manufactured by Nippon Kayaku Co., Ltd.), as well as thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone (Kayacure CTX, manufactured by Nippon Kayaku Co., Ltd.), 2-methylthioxanthone, 2,4-dimethylthioxanthone (Kayacure RTX, manufactured by Nippon Kayaku Co., Ltd.), isopropylthioxanthone, 2,4-dichlorothioxanthone (Kayacure CTX, manufactured by Nippon Kayaku Co., Ltd.), 2,4-diethylthioxanthone (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.), and 2,4-diisopropylthioxanthone (Kayacure DITX, manufactured by Nippon Kayaku Co., Ltd.).Preferably, the photopolymerization initiators include, for example, Irgacure OXE01, Irgacure OXE02, Irgacure OXE03, Irgacure OXE04 (all manufactured by BASF), Omnirad TPO₄H, Omnirad 1300, Omnirad 184, Omnirad 369, Omnirad 379, Omnirad 819, Omnirad 127, Omnirad 907, and Omnirad 1173 (all manufactured by IGM Resins BV), with Omnirad TPO₄H, Irgacure OXE01, Irgacure OXE02, Omnirad 1300, and Omnirad 907 being particularly preferred. These photopolymerization initiators can be used individually or in any proportion when mixed.

[0028] When using benzophenone-based or thioxanthone-based compounds as photopolymerization initiators, it is possible to use auxiliary agents in combination to promote the photopolymerization reaction. Examples of such auxiliary agents include amine compounds such as triethanolamine, methyldiethanolamine, triisopropanolamine, n-butylamine, N-methyldiethanolamine, diethylaminoethyl methacrylate, Michler ketone, 4,4'-diethylaminophenone, ethyl 4-dimethylaminobenzoate, (n-butoxy)ethyl 4-dimethylaminobenzoate, and isoamyl 4-dimethylaminobenzoate. The amounts of the photopolymerization initiator and auxiliary agent described above are preferably used within a range that does not affect the liquid crystalline properties of the composition. The amount is preferably 0.5 parts by mass to 10 parts by mass, and more preferably 2 parts by mass to 8 parts by mass, per 100 parts by mass of the ultraviolet-curable compound in the composition. Furthermore, the amount of the auxiliary agent is preferably 0.5 to 2 times the amount of the photopolymerization initiator.

[0029] <Transparent base material> As an example of two transparent substrates, the example of the support substrate used in the phase difference layer formation described above can be directly applied. Furthermore, it is preferable that the transparent substrate is composed of a support substrate.

[0030] <Adhesive layer> The optical functional film of the present invention is characterized in that a phase difference layer and at least one of two transparent substrates are bonded together by an adhesive layer, the adhesive layer containing (A) a bifunctional (meth)acrylate, (B) a nitrogen-containing monofunctional vinyl monomer, and (C) a hydroxyl group-containing monofunctional (meth)acrylic monomer, and the (A) bifunctional (meth)acrylate is contained in an amount of 0.2 mol% to 6 mol% of the total acrylate components.

[0031] Before forming the adhesive coating layer, one or both of the bonding surfaces may be subjected to an easy-adhesion treatment such as corona discharge treatment, plasma treatment, saponification treatment, flame treatment, primer treatment, or anchor coating treatment.

[0032] The adhesive layer is formed from an active energy ray-curing adhesive. An active energy ray-curing adhesive is an adhesive that hardens when irradiated with active energy rays.

[0033] The active energy ray may be ultraviolet light, visible light, electron beams, X-rays, etc. Any suitable irradiation conditions for the active energy ray can be adopted, as long as they allow the active energy ray-curable adhesive to cure. For example, for electron beam irradiation, the acceleration voltage is preferably 5kV to 300kV, and more preferably 10kV to 250kV. In the case of ultraviolet curing, the light irradiation intensity to the active energy ray-curable adhesive is, for example, 10 to 1000 mJ / cm². 2 This may be the case. The irradiation intensity is preferably in the wavelength range of 400 nm or less. The light is irradiated once or multiple times with such light irradiation intensity, and the integrated light amount is preferably 10 mJ / cm². 2 More preferably, 100 to 1000 mJ / cm² 2 Set it so that it becomes like this.

[0034] The light source used for polymerization curing of the adhesive is not particularly limited, but examples include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, halogen lamps, carbon arc lamps, tungsten lamps, gallium lamps, excimer lasers, LED light sources emitting in the wavelength range of 380-440 nm, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps. From the viewpoint of energy stability and simplicity of equipment, an ultraviolet light source having an emission distribution with a wavelength of 400 nm or less is preferred. Even when using an active energy ray curable composition, heat treatment may be performed simultaneously with or after irradiation with active energy rays.

[0035] Examples of active energy ray curing adhesives include cationic active energy ray curing adhesives containing a cationic polymerizable compound and a cationic polymerization initiator, radical polymerizable active energy ray curing adhesives containing a radical polymerizable compound and a radical polymerization initiator, active energy ray curing adhesives containing both a cationic polymerizable compound and a radical polymerizable compound, and further containing a cationic polymerization initiator and a radical polymerization initiator, and electron beam curing adhesives that do not contain an initiator and are cured by irradiation with an electron beam. From the viewpoint of material cost, equipment, and process simplicity, radical polymerizable active energy ray curing adhesives containing a radical polymerizable compound and a radical polymerization initiator are preferred.

[0036] Examples of radical polymerizable compounds include compounds having ethylenically unsaturated bonds. Such compounds include (meth)acrylic compounds having one or more (meth)acryloyl groups in the molecule, as well as vinyl compounds such as styrene, styrene sulfonic acid, vinyl acetate, vinyl propionate, and N-vinyl-2-pyrrolidone. The radical polymerizable compound is preferably a (meth)acrylic compound. The adhesive may contain one or more radical polymerizable compounds.

[0037] Examples of (meth)acrylic compounds include (meth)acrylate monomers having at least one (meth)acryloyloxy group in the molecule, (meth)acrylamide monomers, and (meth)acryloyl group-containing compounds such as (meth)acrylic oligomers obtained by reacting two or more functional group-containing compounds and having at least two (meth)acryloyl groups in the molecule. The (meth)acrylic oligomer is preferably a (meth)acrylate oligomer having at least two (meth)acryloyloxy groups in the molecule. The (meth)acrylic compounds may be used individually or in combination of two or more.

[0038] Examples of (meth)acrylate monomers include monofunctional (meth)acrylate monomers having one (meth)acryloyloxy group in the molecule, difunctional (meth)acrylate monomers having two (meth)acryloyloxy groups in the molecule, and polyfunctional (meth)acrylate monomers having three or more (meth)acryloyloxy groups in the molecule.

[0039] Alkyl(meth)acrylates are an example of monofunctional (meth)acrylate monomers. In alkyl(meth)acrylates, the alkyl group may be linear or branched as long as it has 3 or more carbon atoms. Specific examples of alkyl(meth)acrylates include methyl(meth)acrylate, ethyl(meth)acrylate, isopropyl(meth)acrylate, butyl(meth)acrylate, isobutyl(meth)acrylate, t-butyl(meth)acrylate, and 2-ethylhexyl(meth)acrylate. Furthermore, aralkyl(meth)acrylates such as benzyl(meth)acrylate; terpene alcohol(meth)acrylates such as isobornyl(meth)acrylate; (meth)acrylates having a tetrahydrofurfuryl structure such as tetrahydrofurfuryl(meth)acrylate; (meth)acrylates that form a tetrahydrofurfuryl structure through cyclization polymerization such as 2-(allyloxymethyl)methyl acrylate, cyclohexylmethyl methacrylate, cyclohexyl(meth)acrylate, dicyclopentanyl acrylate, and dicyclopentenyl(meth)acrylate. Monofunctional (meth)acrylate monomers can also be used, including (meth)acrylates having a cycloalkyl group in the alkyl group, such as 1,4-cyclohexanedimethanol monoacrylate; aminoalkyl (meth)acrylates such as N,N-dimethylaminoethyl (meth)acrylate; and (meth)acrylates having an ether linkage in the alkyl group, such as 2-phenoxyethyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, ethyl carbitol (meth)acrylate, and phenoxypolyethylene glycol (meth)acrylate. It is preferable to include (meth)acrylates having a tetrahydrofurfuryl structure.

[0040] <(C) Hydroxyl group-containing monofunctional (meth)acrylic monomer> It is preferable that the adhesive layer contains 20% by mass or more of a monofunctional (meth)acrylate having a hydroxyl group in the alkyl moiety, relative to the total mass. Alternatively, a monofunctional (meth)acrylate having a carboxyl group in the alkyl moiety may be used. Specific examples of monofunctional (meth)acrylates having a hydroxyl group in the alkyl moiety include 2-hydroxyethyl (meth)acrylate, 2- or 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, trimethylolpropane mono(meth)acrylate, and pentaerythritol mono(meth)acrylate. Specific examples of monofunctional (meth)acrylates having a carboxyl group in the alkyl portion include 2-carboxyethyl (meth)acrylate, ω-carboxy-polycaprolactone (n≒2) mono(meth)acrylate, 1-[2-(meth)acryloyloxyethyl]phthalic acid, 1-[2-(meth)acryloyloxyethyl]hexahydrophthalic acid, 1-[2-(meth)acryloyloxyethyl]succinic acid, 4-[2-(meth)acryloyloxyethyl]trimellitic acid, and N-(meth)acryloyloxy-N',N'-dicarboxymethyl-p-phenylenediamine.

[0041] <(B) Nitrogen-containing monofunctional vinyl monomer> Preferably, the adhesive layer contains 10% by mass or more of nitrogen-containing monofunctional vinyl monomer relative to its total mass; more preferably, 20% by mass or more; particularly preferably 30% by mass or more; and even more preferably 40% by mass or more. The nitrogen-containing monofunctional vinyl monomer is preferably a nitrogen-containing monofunctional (meth)acrylamide monomer or a nitrogen-based heterocyclic monofunctional vinyl monomer. Examples of nitrogen-containing monofunctional (meth)acrylamide monomers include (meth)acrylamides having a substituent at the N-position, where a typical example of the N-position substituent is an alkyl group. Specific examples include N-alkyl(meth)acrylamides such as (meth)acrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, Nn-butyl(meth)acrylamide, Nt-butyl(meth)acrylamide, and N-hexyl(meth)acrylamide; and N,N-dialkyl(methacrylamides such as N,N-dimethyl(meth)acrylamide and N,N-diethyl(meth)acrylamide. Furthermore, the N-substituent may be an alkyl group having a hydroxyl group, and examples include N-hydroxyalkyl(meth)acrylamides such as N-hydroxymethyl(meth)acrylamide, N-(2-hydroxyethyl)(meth)acrylamide, and N-(2-hydroxypropyl)(meth)acrylamide. In addition, it is preferable that the nitrogen-containing monofunctional (meth)acrylamide monomer forms a ring together with the nitrogen atom of (meth)acrylamide. This ring may have an oxygen atom as a ring member in addition to the carbon atom and the nitrogen atom of (meth)acrylamide. Furthermore, substituents such as alkyl or oxo (=O) may be attached to the carbon atoms constituting the ring. Specific examples include 3-(meth)acryloyl-2-oxazolidinone, 4-(meth)acryloylmorpholine, and N-(meth)acryloylpiperidine. Among these, 4-(meth)acryloylmorpholine is preferred. Specific examples of nitrogen-based heterocyclic monofunctional vinyl monomers include N-vinyl-2-pyrrolidone, vinylpyridine, N-vinylcarbazole, N-(meth)acryloylpyrrolidine, 3-(meth)acryloyl-2-oxazolidinone, 4-(meth)acryloylmorpholine, and N-(meth)acryloylpiperidine. Nitrogen-based heterocyclic monofunctional vinyl monomers are preferably nitrogen-based heterocyclic monofunctional (meth)acrylamide monomers, and 4-(meth)acryloylmorpholine is particularly preferred.

[0042] <(A)2 Functional (meth)acrylate> It is preferable that the difunctional acrylate component be contained in an amount of 0.2 mol% to 6 mol% of the total (meth)acrylate component. More preferably, it is preferable that it be contained in an amount of 0.3 mol% to 5.5 mol%. Particularly preferably, it is preferable that it be contained in an amount of 0.4 mol% to 5 mol%. Examples of difunctional (meth)acrylate monomers include alkylene glycol di(meth)acrylate, polyoxyalkylene glycol di(meth)acrylate, halogen-substituted alkylene glycol di(meth)acrylate, aliphatic polyol di(meth)acrylate, hydrogenated dicyclopentadiene or tricyclodecanedialkanol di(meth)acrylate, dioxane glycol or dioxanedialkanol di(meth)acrylate, di(meth)acrylate of alkylene oxide adducts of bisphenol A or bisphenol F, and epoxy di(meth)acrylate of bisphenol A or bisphenol F.

[0043] More specific examples of difunctional (meth)acrylate monomers include ethylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane di(meth)acrylate, pentaerythritol di(meth)acrylate, ditrimethylolpropane di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and polytetramethylene glycol di(meth)acrylate. Examples include acrylate, silicone di(meth)acrylate, di(meth)acrylate of neopentyl glycol hydroxypivalate, 2,2-bis[4-(meth)acryloyloxyethoxyethoxyphenyl]propane, 2,2-bis[4-(meth)acryloyloxyethoxyethoxycyclohexyl]propane, hydrogenated dicyclopentadienyl di(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate, 1,3-dioxane-2,5-diyldi(meth)acrylate (also known as dioxane glycol di(meth)acrylate), di(meth)acrylate of an acetal compound of hydroxypivalaldehyde and trimethylolpropane (chemical name: 2-(2-hydroxy-1,1-dimethylethyl)-5-ethyl-5-hydroxymethyl-1,3-dioxane), tris(hydroxyethyl)isocyanurate di(meth)acrylate, etc.

[0044] Difunctional (meth)acrylates include (meth)acrylic oligomers. Examples of (meth)acrylic oligomers include urethane (meth)acrylic oligomers, polyester (meth)acrylic oligomers, and epoxy (meth)acrylic oligomers.

[0045] A urethane (meth)acrylic oligomer is a compound having a urethane bond (-NHCOO-) and at least two (meth)acryloyl groups in its molecule. Specifically, it can be a urethane reaction product of a hydroxyl group-containing (meth)acrylic monomer having at least one (meth)acryloyl group and at least one hydroxyl group in its molecule, and a polyisocyanate, or a urethane reaction product of a terminal isocyanate group-containing urethane compound obtained by reacting a polyol with a polyisocyanate, and a (meth)acrylic monomer having at least one (meth)acryloyl group and at least one hydroxyl group in its molecule.

[0046] The hydroxyl group-containing (meth)acrylic monomer used in the above urethane reaction can be, for example, a hydroxyl group-containing (meth)acrylate monomer. Specific examples include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, glycerin di(meth)acrylate, trimethylolpropane di(meth)acrylate, pentaerythritol tri(meth)acrylate, and dipentaerythritol penta(meth)acrylate. Specific examples other than hydroxyl group-containing (meth)acrylate monomers include N-hydroxyalkyl (meth)acrylamide monomers such as N-hydroxyethyl (meth)acrylamide and N-methylol (meth)acrylamide.

[0047] Examples of polyisocyanates used in the urethane reaction with hydroxyl group-containing (meth)acrylic monomers include hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, diisocyanates obtained by hydrogenating aromatic isocyanates from among these diisocyanates (e.g., hydrogenated tolylene diisocyanate, hydrogenated xylylene diisocyanate, etc.), di- or tri-isocyanates such as triphenylmethane triisocyanate and dibenzylbenzene triisocyanate, and polyisocyanates obtained by increasing the amount of the above diisocyanates.

[0048] Polyols used to produce terminal isocyanate group-containing urethane compounds by reaction with polyisocyanates include aromatic, aliphatic, or alicyclic polyols, as well as polyester polyols, polyether polyols, and the like. Examples of aliphatic and alicyclic polyols include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, trimethylolethane, trimethylolpropane, ditrimethylolpropane, pentaerythritol, dipentaerythritol, dimethylolheptane, dimethylolpropionic acid, dimethylolbutanoic acid, glycerin, and hydrogenated bisphenol A.

[0049] Polyester polyols are obtained by a dehydration condensation reaction between the polyol described above and a polybasic carboxylic acid or its anhydride. Examples of polybasic carboxylic acids or their anhydrides, indicated by "(anhydride)" if they may be anhydrides, include succinic anhydride, adipic acid, maleic anhydride, itaconic anhydride, trimellitic anhydride, pyromellitic anhydride, phthalic anhydride, isophthalic acid, terephthalic acid, hexahydro(anhydride)phthalic acid, etc.

[0050] Polyether polyols may include polyalkylene glycols, as well as polyoxyalkylene-modified polyols obtained by the reaction of the above-mentioned polyols or dihydroxybenzenes with alkylene oxides.

[0051] Polyester (meth)acrylic oligomers are compounds having an ester bond and at least two (meth)acryloyl groups (typically (meth)acryloyloxy groups) within their molecule. Specifically, they can be obtained by a dehydration condensation reaction using (meth)acrylic acid, a polybasic carboxylic acid or its anhydride, and a polyol. Examples of polybasic carboxylic acids or their anhydrides used in the dehydration condensation reaction, indicated by "(anhydride)" if they can be anhydrides, include (anhydride) succinic acid, adipic acid, (anhydride) maleic acid, (anhydride) itaconic acid, (anhydride) trimellitic acid, (anhydride) pyromellitic acid, hexahydro(anhydride)phthalic acid, (anhydride) phthalic acid, isophthalic acid, terephthalic acid, etc. Furthermore, examples of polyols used in the dehydration condensation reaction include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, trimethylolethane, trimethylolpropane, ditrimethylolpropane, pentaerythritol, dipentaerythritol, dimethylolheptane, dimethylolpropionic acid, dimethylolbutanoic acid, glycerin, and hydrogenated bisphenol A.

[0052] Epoxy (meth)acrylic oligomers can be obtained, for example, by the addition reaction of a polyglycidyl ether with (meth)acrylic acid, and have at least two (meth)acryloyloxy groups in their molecule. Examples of polyglycidyl ethers used in the addition reaction include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and bisphenol A diglycidyl ether.

[0053] The adhesive may further contain a polyfunctional (meth)acrylate monomer with three or more functions. Examples of polyfunctional (meth)acrylate monomers with three or more functions include glycerin tri(meth)acrylate, alkoxylated glycerin tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, and dipentaerythritol penta(meth)acrylate. Typical examples include poly(meth)acrylates of trifunctional or more aliphatic polyols such as erythritol hexa(meth)acrylate, as well as poly(meth)acrylates of trifunctional or more halogen-substituted polyols, tri(meth)acrylates of alkylene oxide adducts of glycerin, tri(meth)acrylates of alkylene oxide adducts of trimethylolpropane, 1,1,1-tris[(meth)acryloyloxyethoxyethoxy]propane, and tris(hydroxyethyl)isocyanurate tri(meth)acrylate.

[0054] The adhesive may consist solely of radical polymerizable compounds, but may also further contain cationic polymerizable compounds.

[0055] <Radical polymerization initiator> When the adhesive contains a radical polymerizable compound, it is preferable to further contain a radical polymerization initiator. The radical polymerization initiator is preferably a photoradical polymerization initiator. One type of photoradical polymerization initiator may be used alone, or two or more types may be used in combination. However, since photocurable compounds have functional groups that undergo chain polymerization reactions by radicals such as double bonds, the use of thermal radical initiators that generate radicals by heat, for example, is not excluded. Photoradical polymerization initiators are not particularly limited as long as they are compounds that generate radicals and initiate a chain polymerization reaction upon irradiation with ultraviolet or visible light, but examples include benzyldimethyl ketal, 1-hydroxycyclohexylphenyl ketone, diethylthioxanthone, benzophenone, 2-ethylanthraquinone, 2-hydroxy-2-methylpropiophenone, 2-methyl-[4-(methylthio)phenyl]-2-morpholino-1-propane, 2,4,6-trimethylbenzoyldiphenylphosphate, camphorquinone, 9-fluorenone, and diphenyl disulfide. Specifically, IRGACURE RTM 651, 184, 2959, 127, 907, 369, 379EG, 819, 784, 754, 500, OXE01, OXE02, DAROCURE RTM 1173, LUCIRIN RTM TPO (both manufactured by BASF), Sequall RTM Examples include Z, BZ, BEE, BIP, and BBI (all manufactured by Seiko Chemical Co., Ltd.). Furthermore, it is preferable that the maximum absorption wavelength λmax of the photoradical polymerization initiator (the longer wavelength if there are two or more) is 340 nm or less. If the wavelength is longer than 340 nm, the storage stability of the adhesive decreases, and deterioration such as gelation may occur depending on the environment. Photopolymerization initiators with a maximum absorption wavelength λmax of 340 nm or less include IRGACURE RTM Examples include 651, 184, 2959, 500, etc., but are not limited to these. When a photoradical polymerization initiator is used, its content is preferably 0.01 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the total amount of the binder resin. A preferred upper limit for this content is 7 parts by mass, more preferably 5 parts by mass, and particularly preferably 4 parts by mass. A preferred lower limit is 0.01 parts by mass, more preferably 0.1 parts by mass, particularly preferably 1 part by mass, and most preferably 1.5 parts by mass. By blending a photoinitiator, the radically polymerizable compound can be sufficiently cured, and the resulting laminate can be given high mechanical strength and adhesive strength. On the other hand, if the amount is excessively large, there is a possibility that the durability may decrease, such as yellowing over time.

[0056] When a thermal radical initiator is used for the photocurable compound, the thermal radical initiator is not particularly limited as long as it is a compound that generates radicals by heating and initiates a chain polymerization reaction. Examples include organic peroxides, azo compounds, benzoin compounds, benzoin ether compounds, acetophenone compounds, benzopinacol, etc., and benzopinacol is preferably used. For example, as the organic peroxide, Kayamec (registered trademark) A, M, R, L, LH, SP-30C, Percadox CH-50L, BC-FF, Cadox B-40ES, Percadox 14, Trigonox RTM 22-70E, 23-C70, 121, 121-50E, 121-LS50E, 21-LS50E, 42, 42LS, Kayaster RTM P-70, TMPO-70, CND-C70, OO-50E, AN, Kayabutil RTM B, Percadox 16, Kayacarbox (registered trademark) BIC-75, AIC-75 (manufactured by Kayaku Akzo Corporation), Permec (registered trademark) N, H, S, F, D, G, Perhexa (registered trademark) H, HC, TMH, C, V, 22, MC, Perkure (registered trademark) AH, AL, HB, Perbutyl (registered trademark) H, C, ND, L, Parkmill (registered trademark) H, D, Peroyl (registered trademark) IB, IPP, Perocta (registered trademark) ND (manufactured by NOF Corporation), etc. are available as commercial products. Further, as the azo compound, VA-044, V-070, VPE-0201, VSP-1001 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), etc. are available as commercial products. When a thermal radical initiator is used, its content is preferably 0.01 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the total amount of the binder resin. The preferable upper limit of this content is 7 parts by mass, more preferably 5 parts by mass, particularly preferably 4 parts by mass, and most preferably 3 parts by mass. A preferred lower limit is 0.01 parts by mass, more preferably 0.1 parts by mass, particularly preferably 1 part by mass, and most preferably 1.5 parts by mass. The most preferred content in the adhesive layer is 1.5 parts by mass or more and 3 parts by mass or less.

[0057] The optical functional film of the present invention is characterized in that a phase difference layer and at least one of two transparent substrates are bonded together by the adhesive layer, and the adhesive strength between the substrate and the adhesive layer is 5N / 25mm or more.

[0058] <Interlayer> The optical laminate of the present invention has an interlayer laminated on the optical functional film described above. The interlayer is preferably a thermoplastic resin film, and particularly preferably a polyvinyl butyral film. The interlayer may be one or more films, but an optical laminate having a structure in which the optical functional film is sandwiched between two interlayer films is preferred.

[0059] Figures 3, 4, and 5 show embodiments of the optical functional film, optical laminate, and functional glass of the present invention, respectively. The optical functional film 10 has a structure in which a phase difference layer 102 formed on a transparent substrate 103 is bonded to another transparent substrate 103 with an adhesive layer 101. The optical laminate 20 has a structure in which the optical functional film 10 is sandwiched between two interlayer films 201. The functional glass 30 has a structure in which the optical laminate 20 is sandwiched between two glass plates 301.

[0060] As the interlayer, a thermoplastic resin can be used, and it is preferable to use an automotive interlayer that is commonly used. Examples of such automotive interlayers include polyvinyl butyral resin (PVB), polyvinyl alcohol resin (PVA), ethylene-vinyl acetate copolymer resin (EVA), or cycloolefin polymer (COP). Interlayers made from these resins are preferred because they are versatile as interlayers for laminated glass. Furthermore, the thickness of the interlayer is not particularly limited as long as it does not affect the reflection of the display light when applying the optical laminate to the HUD system described later, and can be appropriately designed according to the application.

[0061] The interlayer used in the present invention may contain appropriate additives such as ultraviolet absorbers, antioxidants, antistatic agents, heat stabilizers, colorants, and adhesion modifiers. In particular, an interlayer in which infrared-absorbing fine particles are dispersed is important for producing high-performance heat-shielding laminated glass. The infrared-absorbing fine particles used are fine particles of conductive materials such as metals Sn, Ti, Zn, Fe, Al, Co, Ce, Cs, In, Ni, Ag, Cu, Pt, Mn, Ta, W, V, and Mo, oxides of the said metals, said metal nitrides, or composites containing at least two of these. These materials may also be doped with Sn, Sb, F, etc. In particular, tin-doped indium oxide (ITO), antimond-doped tin oxide (ATO), and fluorine-doped tin oxide, which are transparent in the visible light region, are preferred when used as windows for buildings and automobiles where transparency is required. The particle size of the infrared-absorbing fine particles dispersed in the interlayer is preferably 0.2 μm or less. If the particle size of the fine particles is 0.2 μm or less, it is possible to absorb infrared rays while suppressing light scattering in the visible light region, without generating haze, ensuring radio wave transmittance and transparency, while maintaining physical properties such as adhesion, transparency, and durability at the same level as an unadded interlayer, and furthermore, the lamination process can be carried out using a normal laminated glass manufacturing line. When PVB is used as the interlayer, the lamination process is carried out in a room with constant temperature and humidity to maintain the moisture content of the interlayer at an optimal level. In addition, interlayers that are partially colored, sandwich layers with sound insulation properties, or interlayers with a gradient in thickness (wedge shape) to reduce ghosting (double image) in HUDs can be used. There are no particular restrictions on the method of laminating the interlayer and the optical functional film, but one example is to use a nip roll to simultaneously press and laminate the interlayer and the optical functional film. If the nip roll can be heated during lamination, it is also possible to press while heating. Furthermore, if the adhesion between the interlayer and the optical functional film is poor, surface treatment such as corona treatment or plasma treatment may be performed beforehand before lamination.

[0062] The interlayer may be dissolved in a solvent and directly laminated to one or both sides of the optical functional film. When using polyvinyl butyral resin (PVB), the lower limit of the degree of butyralization is preferably 40 mol%, more preferably 55 mol%, and particularly preferably 60 mol%. On the other hand, the upper limit of the degree of butyralization is preferably 85 mol%, more preferably 80 mol%, and particularly preferably 75 mol%. The degree of butyralization can be measured by infrared absorption spectroscopy (IR), for example, using FT-IR.

[0063] The lower limit of the hydroxyl group content of polyvinyl butyral resin is preferably 15 mol%, and the upper limit is preferably 35 mol%. If the hydroxyl group content is less than 15 mol%, the adhesion between the interlayer for laminated glass and the glass may decrease, or the puncture resistance of the laminated glass may decrease. On the other hand, if the hydroxyl group content exceeds 35 mol%, the interlayer may become hard.

[0064] Polyvinyl butyral resins can be prepared by acetalizing polyvinyl alcohol with an aldehyde. Polyvinyl alcohol is usually obtained by saponifying polyvinyl acetate, and polyvinyl alcohol with a saponification degree of 80 mol% to 99.8 mol% is generally used. Furthermore, the upper limit of the degree of polymerization of polyvinyl alcohol is preferably 4000, more preferably 3000, and particularly preferably 2500. If the degree of polymerization exceeds 4000, it may become difficult to form the interlayer film.

[0065] <glass plate> The functional glass of the present invention has a glass plate laminated with the above-mentioned optical functional film or optical laminate. The glass plate may be one or multiple plates, but a functional glass having a structure in which the above-mentioned optical functional film or optical laminate is sandwiched between two glass plates is preferred. Such a functional glass is suitably used as a display medium in a HUD system.

[0066] Functional glass is manufactured, for example, by laminating the above-mentioned optical functional film or optical laminate onto a glass plate. One example of a method for laminating an optical functional film or optical laminate onto a glass plate is to apply an adhesive or bonding agent to one or both sides of the optical functional film or optical laminate, and then laminate the glass plate onto it. There are no particular restrictions on the adhesive or bonding agent, but if it is necessary to peel it off later, a material with good adhesion and excellent reworkability, such as a silicone adhesive or an acrylic adhesive, is preferred.

[0067] The glass plate is not particularly limited as long as it has sufficient transparency to allow for a clear view of the scenery ahead, even when using the functional glass of the present invention as a windshield. Furthermore, the refractive index of the glass plate is preferably 1.2 to 2.0, and more preferably 1.4 to 1.8. The thickness, shape, etc., of the glass plate are also not particularly limited as long as they do not affect the reflection of the displayed light, and can be appropriately designed according to the application. These glass plates may also be provided with a multilayer reflective coating and a thin metal film layer that also serves as a heat shield on the reflective surface. These coatings can improve the reflectance of incident polarized light, but when using the functional glass of the present invention as an automobile windshield, for example, it is preferable to adjust the reflectance so that the visible light transmittance of the functional glass is 70% or more.

[0068] When using the optical functional film or optical laminate of the present invention, a functional glass in which the optical laminate is arranged within laminated glass can be obtained by placing the optical functional film or optical laminate between two glass plates and bonding them under high temperature and high pressure. Figure 5 shows one embodiment of a functional glass according to the present invention. The functional glass 30 shown in Figure 5 has a configuration in which an optical laminate 20 is sandwiched between two glass plates 301, and the optical laminate 20 has an optical film 10 sandwiched between two interlayer films 102. As shown in Figure 5, when the optical laminate 20 constitutes the functional glass 30, the interlayer film 201 also functions as an adhesive or bonding agent to maintain adhesion between the two glass plates 301 and the optical laminate 20.

[0069] An example of a method for producing functional glass using the optical functional film or optical laminate of the present invention will be specifically described. First, two glass plates are prepared. When used as laminated glass for automobile windshields, soda-lime glass produced by the float process is used. The glass can be transparent or colored green, and there are no particular restrictions. The thickness of these glass plates is usually about 2 mm, but in response to the recent demand for lighter glass, glass plates with a slightly thinner thickness can also be used. The glass plates are cut into a predetermined shape, the glass edges are chamfered and cleaned. If a black frame or dot pattern print is required, it is printed onto the glass plate. If a curved shape is required, such as for a windshield, the glass plates are heated to 650°C or higher, and then shaped so that the two plates have the same surface shape by pressing with a mold or bending by their own weight, and the glass is cooled. At this time, if the cooling rate is increased too much, stress distribution will occur in the glass plate and it will become tempered glass, so it is cooled slowly. One of the glass plates prepared in this way is placed horizontally, the optical functional film or optical laminate of the present invention is placed on top of it, and then the other glass plate is placed on top of that. Next, the optical functional film and interlayer that protrude from the edges of the glass are cut and removed with a cutter. After that, the glass plate, optical functional film or optical laminate, which are stacked in a sandwich-like manner, are heated to a temperature of 80°C to 100°C while degassing the air present between them to perform preliminary bonding. There are two methods for degassing the air: the bag method, in which the glass plate / optical functional film or optical laminate / glass plate laminate is wrapped in a rubber bag made of heat-resistant rubber or the like, and the ring method, in which only the edges of the glass plate are covered and sealed with rubber rings. Either method may be used. After preliminary bonding is complete, the glass plate / optical functional film or optical laminate / glass plate laminate removed from the rubber bag, or the laminate with the rubber rings removed, is placed in an autoclave at 10-15 kg / cm³. 2Under high pressure, the material is heated to 120°C to 150°C and subjected to heating and pressurizing treatment for 20 to 40 minutes. After treatment, it is cooled to below 50°C, the pressure is released, and the functional glass of the present invention, consisting of a glass plate / optical functional film or an optical laminate / glass plate, is removed from the autoclave.

[0070] The functional glass obtained in this way can be used as windshields, side windows, rear windows, and roof windows for regular cars, compact cars, and light vehicles, as well as for large and small special-purpose vehicles. Furthermore, it can be used as windows for railway cars, ships, and aircraft, as well as for building materials and industrial window materials. In terms of usage, it can be used by laminating or bonding it with components that have UV-cutting or light-adjusting functions.

[0071] <Head-Up Display System> Figure 1 is a schematic diagram of one embodiment of the HUD system of the present invention. The HUD system shown in Figure 1 comprises a display image projection means (display) 2 that emits display light that shows a display image in S-polarized or P-polarized form, a reflector 3 that reflects the display light emitted from the display image projection means 2, and a functional glass for a head-up display of the present invention into which the S-polarized or P-polarized light emitted from the display image projection means 2 is incident. By reflecting the S-polarized or P-polarized light emitted from the display image projection means 2 with the reflector 3 and irradiating this reflected display light onto the functional glass 4 which functions as a windshield, the S-polarized or P-polarized light reaches the observer 1 via the optical path 5, and the virtual image 6 of the display image can be seen. In the HUD system shown in Figure 1, the display light emitted from the display image projection means 2 is incident on the functional glass 4 via the reflector 3, but it may also be incident directly on the functional glass 4 from the display image projection means 2. Alternatively, the display image projection means 2 may emit display light representing the display image as random light, reflect it with the reflector 3, and pass this reflected light through a polarizing plate before it reaches the functional glass 4, thereby adjusting the polarization emitted from the display image projection means 2 and irradiating the functional glass 4 with a desired polarization. When the incident light is S-polarized, a portion of the light incident on the functional glass 4 at the Brewster angle is reflected directly from the surface of the functional glass 4 and is visible to observer 1. On the other hand, the incident light that has passed through the functional glass 4 is converted to P-polarized by a half-wave plate inside. Subsequently, when the light is emitted from the functional glass 4 into the air, it is at the Brewster angle, so the reflection of P-polarized light is suppressed, and ghosting is less likely to occur. Also, when the incident light is P-polarized, by causing it to be incident on the functional glass 4 at the Brewster angle, reflection at the glass surface is suppressed, and ghosting is less likely to occur. On the other hand, the incident light that has passed through the functional glass 4 is converted to S-polarized by a half-wave plate inside. Subsequently, when the light is emitted from the functional glass 4 into the air, it is reflected directly and is visible to observer 1. As described above, regardless of the type of polarized light, by using the head-up display system in the manner of the present invention, ghosting is suppressed, and a head-up display with excellent visibility can be provided.

[0072] <Display image projection means> The display image projection means 2 is not particularly limited as long as it can emit the desired P-polarized or S-polarized light before finally reaching the functional glass 4, but examples include liquid crystal display devices (LCDs) and organic light-emitting diode (OLEDs). When the display image projection means 2 is a liquid crystal display device, the emitted light is usually linearly polarized, so it can be used as is. On the other hand, when the display image projection means 2 is an organic EL display, for example, the display image projection means 2 may consist of a light source and a polarizer capable of emitting P-polarized or S-polarized light. Furthermore, when the HUD system is used in an automobile, the liquid crystal display device and organic EL display can be adjusted so that P-polarized or S-polarized light is emitted from the display image projection means 2 by placing optical elements such as polarizers and half-wave plates at a light output opening, such as a dashboard. Furthermore, the light source used for the display image projection means 2 is not particularly limited, and laser light sources, LED light sources, etc., can be used. In addition, by setting the central reflection wavelength of the phase difference element constituting the optical functional layer to correspond to the emission spectrum of the above light source, the displayed image can be made sharper more effectively.

[0073] The HUD system of the present invention may optionally include a reflector 3. The reflector 3 is not particularly limited as long as it can reflect the display light from the display image projection means 2 toward the functional glass 4, and can be composed of, for example, a planar mirror or a concave mirror. When a concave mirror is used as the reflector 3, the concave mirror can also magnify the display light from the display at a predetermined magnification.

[0074] In the HUD system according to the present invention, when the Brewster angle of S-polarized or P-polarized light with respect to the functional glass 4 is α, the incident angle at which the light emitted from the display image projection means 2 enters the functional glass 4 as a display medium is preferably in the range of α-10° to α+10°, and more preferably in the range of α-5° to α+5°. The incident angle refers to the angle between an axis perpendicular to the surface of the display medium (functional glass 4) and the light incident on the surface of the display medium (hereinafter, this incident angle will also be referred to as "incident angle X").

[0075] In one embodiment of the HUD system of the present invention, when a half-wave plate is used as the optical functional film, the display medium is functional glass 4, and the display light emitted from the display image projection means 2 is S-polarized, by incidenting the S-polarized light emitted from the display image projection means 2 through the reflector 3 at an incident angle in the range of α-10° to α+10°, that is, near the Brewster angle with respect to an axis perpendicular to the surface of the functional glass 4, preferably at the Brewster angle α, the reflection of the P-polarized light converted by the functional glass 4 by the glass plate on the outside of the vehicle can be suppressed, thereby preventing the occurrence of double images. That is, when the incident angle of the S-polarized light is less than α-10° or greater than α+10°, the incident angle of the S-polarized light deviates from near the Brewster angle, which can increase the reflection of the P-polarized light converted by the half-wave plate, potentially causing double images.

[0076] In the head-up display system of the present invention, when a functional glass including an optical functional film equipped with a half-wave plate is provided, for example, in order to efficiently perform polarization conversion (for example, converting P-polarized light to S-polarized light, or S-polarized light to P-polarized light), it is preferable to control the angle θ between the polarization axis of S-polarized light or P-polarized light incident from a position inclined at 45° to 65° from an axis perpendicular to the surface of the functional glass, and the slow axis of the optical functional film to 35° to 47°. By setting the incident angle of S-polarized light or P-polarized light incident on the functional glass to a range of 45° to 65°, when P-polarized light is incident on the functional glass, the reflectance on the surface of the functional glass can be theoretically suppressed to 2% or less. The transmitted P-polarized light is converted to S-polarized light by the half-wave plate, and the converted S-polarized light is reflected at the interface between the functional glass and air on the opposite side of the incident side. The reflected S-polarized light is converted back to P-polarized light by the half-wave plate, and this P-polarized light reaches the observer. Furthermore, when S-polarized light is incident on functional glass, it is reflected by the surface of the functional glass, and this S-polarized light reaches the observer. Some of the transmitted S-polarized light is converted to P-polarized light by the half-wave plate, and the converted P-polarized light is not reflected by the functional glass on the opposite side of the incident side or by the interface between the functional glass and the air, but passes through. In this way, by controlling the incident angle X of the S-polarized or P-polarized light incident on the functional glass, the occurrence of double images can be suppressed. Also, if the angle θ is less than 35° or greater than 47°, the polarization axis conversion performance of the functional glass, which converts P-polarized light to S-polarized light or S-polarized light to P-polarized light, is low, and as a result, double images may occur. By appropriately controlling this angle θ, the half-wave plate exhibits good polarization axis conversion performance, and as a result, the displayed image becomes clearer.

[0077] When an optical functional film is equipped with a half-wave plate, the angle θ is preferably a value calculated from the following equations (2) and (3) in order to appropriately control the polarization axis conversion performance. Here, the technical significance of the following equations (2) and (3) is explained. When S-polarized or P-polarized light incident on functional glass passes through a half-wave plate, which is a medium having a refractive index different from that of air, the incident angle X incident on the half-wave plate changes. Here, the incident angle X of the S-polarized or P-polarized light on the functional glass is α, the incident angle X actually incident on the half-wave plate, i.e., the refraction angle of the half-wave plate is β, and the refractive index of air is n α The refractive index of the half-wave plate is n β Therefore, according to Snell's Law, sinα / sinβ = n β / n αThe following equation holds true, and by simplifying this equation to one in which β can be found, equation (3) is derived. On the other hand, if the polarization axis of the S-polarized light incident on the functional glass is the x-axis, the polarization axis of the P-polarized light is the y-axis, and the angle between the y-axis and the slow axis of the half-wave plate is θ, then the phase difference value is Re, and by vector analysis, the y-axis is expressed as Re·cosθ and the x-axis as Re·sinθ. Here, it is known that the polarization axis conversion performance of the half-wave plate is maximized when light is incident at 45° with respect to the slow axis of the half-wave plate, so theoretically, it is desirable that the angle θ between the polarization axis of the S-polarized light or the polarization axis of the P-polarized light and the slow axis of the optical functional film be 45°. However, as mentioned above, even if the angle between the polarization axis of the S-polarized light or the polarization axis of the P-polarized light incident on the functional glass and the slow axis of the optical functional film is θ, in reality, the angle at which the light is incident on the half-wave plate is β. Therefore, when the y-axis of Re·cosθ (theoretical y-axis) is tilted at an angle β around the x-axis, the y-axis (effective y-axis) is found to be Re·cosθ / effective y-axis = sin(90°-β), and the effective y-axis is expressed as Re·cosθcosβ. As mentioned above, it is desirable that the angle between the slow axis of the half-wave plate and the polarization axis of S-polarized or P-polarized light is 45°. In order to make the angle between the polarization axis of S-polarized or P-polarized light incident on the functional glass and the slow axis of the half-wave plate 45°, it is necessary to make the x-axis (Re·sinθ) and the effective y-axis (Re·cosθcosβ) equal, so Re·sinθ = Re·cosθcosβ is obtained. By simplifying this equation, equation (2) is derived. Thus, by precisely controlling the angle θ in relation to the angle β at which light actually enters the half-wave polarizer, based on the values ​​calculated from equations (2) and (3) below, the polarization axis conversion performance exhibited by the half-wave plate can be maximized.

[0078]

number

[0079] The range of angle θ is preferably controlled within ±5° of the value of the angle θ, and more preferably within ±3°. If the angle θ is outside the ±5° range of the angle that satisfies the value calculated from equations (2) and (3) above, the polarization conversion efficiency exhibited by the half-wave plate will be low. By controlling the range of angle θ based on the value calculated from equations (2) and (3) above, the decrease in polarization conversion efficiency by the half-wave plate can be suppressed.

[0080] The refractive index of the half-wave plate substituted into equation (3) is obtained by taking the average of the sum of the refractive index in the slow axis direction of the half-wave plate, nx, the refractive index in the direction perpendicular to nx within the plane of the half-wave plate (ny), and the refractive index in the thickness direction of the half-wave plate (nz). When using a commercially available half-wave plate, the average refractive index can be the value listed in the catalog, etc. Furthermore, when using a polymerizable liquid crystal as the material for the half-wave plate, the average refractive index can be expressed as (nx + ny + nz) / 3 = (no + no + ne) / 3, using the liquid crystal's intrinsic ordinary refractive index no and extraordinary refractive index ne. To give specific examples of θ calculated from equations (2) and (3), for example, if the refractive index of air is 1.00, a half-wave plate with a refractive index of 1.55 is used, and the incident angle X of S-polarized or P-polarized light is 45°, then based on equations (2) and (3), the value of θ is 42°, so the range of θ is preferably 37° to 47°, and more preferably 39° to 45°. If the incident angle X of S-polarized or P-polarized light is 50°, then based on equations (2) and (3), the value of θ is 41°, so the range of θ is preferably 36° to 46°, and more preferably 38° to 44°. Also, if the incident angle X of S-polarized or P-polarized light is 56° or 60°, then based on equations (2) and (3), the value of θ is 40°, so the range of θ is preferably 35° to 45°, and more preferably 37° to 43°. Furthermore, when the incident angle X of S-polarized or P-polarized light is 65°, based on equations (2) and (3), the value of θ is 39°, so the range of θ is preferably 34° or more and 44° or less, and more preferably 36° or more and 42° or less.

[0081] As described above, in the present invention, the polarization axis conversion performance exhibited by the half-wave plate can be further enhanced by controlling the angle θ between the polarization axis of S-polarized or P-polarized light incident on the optical functional film and the slow axis of the half-wave plate. In such cases, from the viewpoint of controllability of the slow axis of the half-wave plate and production cost, it is particularly preferable to use a half-wave plate that includes a polymerizable liquid crystal layer as the layer that has the effect of converting the polarization axis. The wavelength dispersion of the half-wave plate as described above is not particularly limited as long as it is suitable for head-up display applications, but it is desirable to have inverse wavelength dispersion in order to accurately convert polarization over a wide wavelength range in the visible light region. Generally, polymers exhibit normal dispersion in which the absolute value of birefringence is larger on the shorter wavelength side, but inverse wavelength dispersion can be obtained if the liquid crystal compound is such that the birefringence is larger on the longer wavelength side by controlling the value of the birefringence Δn for each wavelength of visible light. Inverse wavelength dispersion can also be obtained by lamination of multiple phase difference plates with appropriate phase difference values ​​according to the wavelength dispersion characteristics of the compound and appropriate combinations of slow axes. Even when using a half-wave plate formed by laminating multiple phase difference plates in this manner, by appropriately controlling the angle θ between the polarization axis of the S-polarized or P-polarized light incident on the optical functional film and the slow axis of the half-wave plate, as described above, the half-wave plate exhibits good polarization axis conversion performance, and as a result, the displayed image becomes even clearer. [Examples]

[0082] The present invention will be described in detail below with reference to examples. In the examples, "parts" means parts by mass. The present invention is not limited to the following examples unless it exceeds the spirit of the invention. Unless otherwise specified, room temperature is defined as being within the range of 20°C ± 5°C.

[0083] [Example 1] <Preparation of coating solution (adhesive)> The components A to I listed below were mixed in the compositional ratios shown in Table 1 to prepare the coating solutions (adhesives 1 to 13). Note that the component amounts in Table 1 are in parts by mass. A: Urethane acrylate (UX-0937, manufactured by Nippon Kayaku Co., Ltd.) B: Bisphenol A type epoxy acrylate (VISCOAT700HV, manufactured by Osaka Organic Chemical Industry Co., Ltd.) C: Acryloylmorpholine (manufactured by ACMO KJ Chemicals) D: 4-Hydroxybutyl acrylate (4-HBA, manufactured by Osaka Organic Chemical Industry Co., Ltd.) E: Tetrahydrofurfuryl acrylate (Viscote #150, manufactured by Osaka Organic Chemical Industry Co., Ltd.) F: Hydroxycyclohexyl phenyl ketone (Irgacure 184, BASF) G: 2,4,6-Trimethylbenzoyldiphenylphosphine oxide (Speedcure TPO, manufactured by Lambson Japan Co., Ltd.) [Table 1]

[0084] <Preparation of coating solution (liquid crystal composition)> A coating solution Z with the composition shown in Table 2 was prepared.

[0085] [Table 2]

[0086] <Fabrication of phase difference layer> Half-wave plates were fabricated using the prepared coating solution Z according to the following procedure. An orientation treatment was performed by applying the photo-alignment coating solution to a 60 μm thick TAC film (manufactured by Fujifilm Corporation) as a transparent resin substrate, and then drying and curing it. The orientation angle was set so that the angle between the longitudinal direction of the film and the slow axis of the half-wave plate (hereinafter also referred to as the "slow axis angle") was 50°.

[0087] (i) The coating solution Z was applied at room temperature to the orientation-treated surface of the TAC film using a wire bar so that the thickness of the half-wave plate obtained after drying was approximately 2 μm. (ii) The obtained coated film was heated at 50°C for 2 minutes to remove the solvent and form a liquid crystal phase. Next, the liquid crystal phase was irradiated with UV light from a high-pressure mercury lamp (Harrison Toshiba Lighting Co., Ltd.) at an output of 120W for 5 to 10 seconds to fix the liquid crystal phase, and a polymerizable liquid crystal layer was laminated on the TAC film to fabricate a half-wave plate. The phase difference value of the half-wave plate was measured with an automatic birefringence meter (KOBRA-21ADH, Oji Instruments Co., Ltd.), and the phase difference value at 546 nm was 275 nm (lagging axis angle 50°).

[0088] <Fabrication of optical functional films> As described above, the phase difference layer surface and a 60 μm thick TAC film (manufactured by Fujifilm Corporation) used as a transparent resin substrate were subjected to corona treatment (conditions: 0.3 kW, 3 m / min). Then, using a PI-1210 automatic coating device manufactured by Tester Industries Co., Ltd., adhesive 1 was applied to the phase difference layer surface and laminated with a laminator to bond with the corona-treated surface of the TAC film. Next, the laminated structure was UV-irradiated with a high-pressure mercury lamp (manufactured by Harrison Toshiba Lighting Corporation) at 120 W output for 5 to 10 seconds to cure the adhesive and obtain laminated film 1. The thickness of the adhesive layer was adjusted to approximately 8 μm. Subsequently, laminated film 1 was immersed in a 2 mol / L potassium hydroxide aqueous solution heated to 40°C for 5 minutes, washed with water, and then dried at 70°C for 5 minutes to produce the optical functional film 1 of the present invention.

[0089] <Evaluation of Adhesion> The optical functional film was heated at 140°C for 30 minutes, allowed to return to room temperature, cut into strips 25 mm wide and 100 mm long, attached to a flat glass plate with double-sided tape, and subjected to a 180° peel test at a peeling speed of 300 mm / min. The results are shown in Table 3. The peel interface was between the TAC film and the adhesive layer.

[0090] <Fabrication of optical laminates> A transparent polyvinyl butyral interlayer with a thickness of 0.38 mm and containing triethylene glycol-di-2-ethylhexanoate as a plasticizer, along with an optical functional film, were cut to a size of 150 cm square. The optical functional film was placed between two polyvinyl butyral interlayers, and then pressed together using a laminator to obtain the optical laminate 1 of the present invention.

[0091] <Fabrication of functional glass> The functional glass of the present invention was obtained by placing the optical laminate between two glass plates, each the same size as the optical laminate (15 cm square) and 2 mm thick, and then applying pressure and heating. First, the optical laminate and the transparent glass plate were stacked on top of a transparent glass plate. This was wrapped in a rubber bag and degassed in an autoclave heated to 90°C for 10 minutes to pre-bond the layers. After cooling to room temperature, it was removed from the rubber bag and again heated in an autoclave at 140°C and 12 kg / cm². 2 Functional glass 1 with a good appearance was produced by heating and pressurizing under high pressure for 30 minutes.

[0092] <Evaluation of interlayer adhesion in functional glass> Functional glass was cooled at -20°C for more than 4 hours. The glass surface was tilted 5° upward from the base, starting from one edge, and fixed in place so that there was space beneath the glass surface. Next, a 1-pound hammer was used to strike the glass surface five times at equal intervals in the horizontal direction from the corner up to 7 cm, and then the same five times in the vertical direction from the corner up to 7 cm, shifting vertically at equal intervals. This process was repeated five times for a total of 25 blows. This was repeated once more for a total of 50 blows. After that, the glass was turned over, and the 7 cm square area on the back, diagonally opposite the areas struck on the front, was struck 50 times in the same manner. After all the blows, the adhesion between layers in the unstruck areas was evaluated after the glass had cooled to room temperature. ◎ was used to indicate that 90% or more of the adhesion between the TAC film and the adhesive layer, and between the phase difference layer and the adhesive layer was maintained; ○ was used to indicate that 80% or more of the adhesion was maintained; △ was used to indicate that 20% to 50% of the interface between the TAC film and the adhesive layer, and between the phase difference layer and the adhesive layer had peeled off; and × was used to indicate that more than 50% had peeled off. The results are shown in Table 3.

[0093] [Examples 2-9] Optical functional films 2-9 and functional glass 2-9 were obtained in the same manner as in Example 1, except that adhesives 2-9 were used instead of adhesive 1. The adhesion of the optical functional films and the interlayer adhesion of the functional glass were evaluated in the same manner. The results are shown in Table 3.

[0094] [Comparative Examples 1-4] Optical functional films 12-17 and functional glasses 10-13 were obtained in the same manner as in Example 1, except that adhesives 10-13 were used instead of adhesive 1. The adhesion of the optical functional films and the interlayer adhesion of the functional glasses were evaluated in the same manner. The results are shown in Table 3.

[0095] [Table 3]

[0096] As shown in Table 3, in Examples 1 to 9, the nitrogen-based heterocyclic monofunctional monomer and difunctional component were present in 0.2 to 6 mol% amounts, and the hydroxyl group-containing acrylate was also present, resulting in an adhesive strength of 5 N / 25 mm or more with the TAC film, and good interlayer adhesion in laminated glass. On the other hand, Comparative Example 1, which had a difunctional component ratio of 6 mol% or more, exhibited an adhesion strength lower than 5 N / 25 mm to the TAC film, resulting in insufficient interlayer adhesion in the laminated glass. Comparative Example 2 did not contain nitrogen-based heterocyclic monofunctional monomers (ACMO), resulting in an adhesion strength lower than 5 N / 25 mm to the TAC film, resulting in insufficient interlayer adhesion in the laminated glass. Comparative Example 3 had a difunctional component ratio of 6 mol% or more and did not contain nitrogen-based heterocyclic monofunctional monomers (ACMO), resulting in an adhesion strength lower than 5 N / 25 mm to the TAC film, resulting in insufficient interlayer adhesion in the laminated glass. Comparative Example 4 did not contain hydroxyl group-containing monofunctional monomers, resulting in an adhesion strength lower than 5 N / 25 mm to the phase difference layer, resulting in insufficient interlayer adhesion in the laminated glass. [Industrial applicability]

[0097] The head-up display system equipped with the optical functional film of the present invention has the ability to convert polarization when a virtual image is projected onto the windshield, can suppress the occurrence of double images, allows the viewer to use the head-up display system without stress, and has good interlayer adhesion after laminated glass processing at high temperatures, resulting in superior windshield safety. [Explanation of Symbols]

[0098] 1 Observer 2. Image display means 2A light source 2B Polarizing plate 3 Reflector 4. Windshield 5 light path 6 Display Images 10 Optical Functional Films 101 Adhesive layer 102 Retardation layer 103 Transparent base material 20 Optical laminate 201 Interlayer 30 Functional Glass 301 Glass plate

Claims

1. An optical functional film in which a phase difference layer and a transparent substrate are bonded together by an adhesive layer, The adhesive layer contains (A) a bifunctional (meth)acrylate, (B) a nitrogen-containing monofunctional vinyl monomer, and (C) a hydroxyl-containing monofunctional (meth)acrylic monomer. An optical functional film for a head-up display, containing the aforementioned (A) bifunctional (meth)acrylate in an amount of 0.2 mol% to 6 mol% of the total acrylate components.

2. The optical functional film for a head-up display according to claim 1, wherein the (B) nitrogen-containing monofunctional vinyl monomer is contained in an amount of 10% by mass or more relative to the total mass of the adhesive layer.

3. The optical functional film for a head-up display according to claim 1, wherein the (B) nitrogen-containing monofunctional vinyl monomer is a nitrogen-containing monofunctional (meth)acrylamide monomer.

4. The optical functional film for a head-up display according to claim 3, wherein the nitrogen-containing monofunctional (meth)acrylamide monomer is at least one selected from the group consisting of (meth)acrylamide, N-alkyl(meth)acrylamide, N,N-dialkyl(meth)acrylamide, N-hydroxyalkyl(meth)acrylamide, 3-(meth)acryloyl-2-oxazolidinone, 4-(meth)acryloylmorpholin, and N-(meth)acryloylpiperidine.

5. The optical functional film for a head-up display according to claim 1, wherein the nitrogen-containing monofunctional vinyl monomer is a nitrogen-based heterocyclic monofunctional vinyl monomer.

6. The optical functional film for a head-up display according to claim 5, wherein the nitrogen-based heterocyclic monofunctional vinyl monomer is at least one selected from the group consisting of N-vinyl-2-pyrrolidone, vinylpyridine, N-vinylcarbazole, N-(meth)acryloylpyrrolidine, 3-(meth)acryloyl-2-oxazolidinone, 4-(meth)acryloylmorpholin, and N-(meth)acryloylpiperidine.

7. The optical functional film for a head-up display according to claim 1, wherein the (C) hydroxyl group-containing monofunctional (meth)acrylic monomer is contained in an amount of 20% by mass or more relative to the total mass of the adhesive layer.

8. The optical functional film for a head-up display according to claim 1, wherein the phase difference layer is a polymerizable liquid crystal layer having a polymerizable liquid crystal compound.

9. The optical functional film for a head-up display according to claim 1, wherein the phase difference layer is a half-wave plate.

10. An optical laminate for a head-up display comprising an optical functional film for a head-up display according to any one of claims 1 to 9 and an interlayer.

11. A functional glass for a head-up display, comprising an optical functional film for a head-up display according to any one of claims 1 to 9, or an optical laminate for a head-up display according to claim 10, between two glass plates.

12. A display device and a head-up display system using the functional glass for head-up displays described in claim 11 as a display medium.

13. The head-up display system according to claim 12, wherein the light emitted from the display device is S-polarized.

Images