Optical laminate and image display device including the same

Abstract

The present invention provides an optical laminate in which decoloring of an end portion is suppressed, and an image display device having the optical laminate. An optical laminate according to the present invention comprises, in the following order: a cover glass having a transmittance of 7-50% at a wavelength of 243 nm; a first adhesive layer comprising a first adhesive composition as an ultraviolet curable adhesive; a polarizing plate including a polarizer and a protective layer laminated on at least one surface of the polarizer; and a second adhesive layer comprising a second adhesive composition.

Description

Technical Field

[0001] The present invention relates to an optical layered body and an image display device having the optical layered body. Background Art

[0002] Polarizers are typically manufactured by dyeing a polyvinyl alcohol (PVA) resin film with a dichroic substance such as iodine (for example, Patent Documents 1 and 2). It is known that the iodine complex of a polarizer is destroyed due to moisture absorption, and iodine is dissolved, thereby reducing the degree of polarization and increasing the transmittance (decolorization). Since water invades the polarizer from the end, there is a tendency for decolorization to become significant at the end. In addition, in recent years, the image display device using a polarizer has been thinned, and sometimes a protective layer is used on only one side of the polarizer. For a polarizer having a protective layer on only one side, decolorization of the polarizer may become more problematic.

[0003] In image display devices such as mobile phones and notebook personal computers, polarizers are widely used to realize image display and / or improve the performance of the image display. In recent years, due to the rapid popularization of smart phones and touch panel information processing devices, image display devices equipped with cameras have been widely used. Correspondingly, polarizers having through holes at positions corresponding to the camera parts are also widely used. In polarizers having such through holes, various research items exist in the through holes or in the vicinity thereof. In addition, in order to impart surface hardness and impact resistance, image display devices sometimes have a cover glass laminated on the outermost surface. Representatively, in an image display device, an optical laminate is laminated with a cover glass via an adhesive composition. In an optical laminate laminated with a cover glass via an adhesive composition, excessive discoloration of the end portion is sometimes produced that is different from the case where a polarizer (for example, a polarizer comprising a polarizer and a protective layer) is alone.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 5048120

[0007] Patent Document 2: Japanese Patent Application Publication No. 2013-156391 Summary of the invention

[0008] Problems to be solved by the invention

[0009] The present invention has been made to solve the above-mentioned conventional problems, and a main object of the present invention is to provide an optical layered body in which end portion discoloration is suppressed.

[0010] Means for solving problems

[0011] 1. An optical laminate according to an embodiment of the present invention comprises, in order: a cover glass having a transmittance of 7% to 50% at a wavelength of 243 nm; a first adhesive layer composed of a first adhesive composition as an ultraviolet curable adhesive; a polarizing plate comprising a polarizer and a protective layer laminated on at least one surface of the polarizer; and a second adhesive layer composed of a second adhesive composition.

[0012] 2. The optical laminate according to 1 above, wherein the polarizer may have a through hole, and the through hole is filled with the first adhesive composition.

[0013] 3. In the optical laminate according to 1 or 2 above, the protective layer may be laminated only on the surface of the polarizer on the cover glass side.

[0014] 4. The optical layered body according to any one of 1 to 3 above, wherein the first adhesive composition may contain a base polymer having an amide skeleton and an acylphosphine oxide-based photopolymerization initiator.

[0015] 5. The optical layered body according to any one of 1 to 4 above, wherein the cover glass contains a metal oxide of an alkaline earth metal.

[0016] 6. In the optical layered body according to 5 above, the content of the metal oxide of the alkaline earth metal in the cover glass may be 2% by weight to 12% by weight.

[0017] 7. In the optical layered body according to any one of 1 to 6 above, the polarizer may have a thickness of 15 μm or less.

[0018] 8. According to another aspect of the embodiment of the present invention, an image display device is provided. The image display device includes the optical layered body according to any one of 1 to 7 above.

[0019] 9. The image display device described in 8 above may include the optical layered body described in 2 above, and may include a camera unit at a position corresponding to the through hole.

[0020] Effects of the Invention

[0021] According to an embodiment of the present invention, an optical layered body having an edge portion discoloration suppressed even when a cover glass is laminated can be provided. The optical layered body according to an embodiment of the present invention can suppress edge portion discoloration even when placed under more severe conditions such as a humidity reliability evaluation test. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic cross-sectional view of an optical layered body according to one embodiment of the present invention.

[0023] Explanation of symbols

[0024] 10 Polarizer

[0025] 11 Polarizer

[0026] 12. Protective layer

[0027] 13. Protective layer

[0028] 15 Through hole

[0029] 20 1st adhesive layer

[0030] 30 coverslips

[0031] 40 2nd adhesive layer

[0032] 100 Optical laminate

[0033] 200 LCD Panel DETAILED DESCRIPTION

[0034] (Definition of Terms and Symbols)

[0035] The definitions of terms and symbols in this specification are as follows.

[0036] (1) Refractive index (nx, ny, nz)

[0037] “nx” is the refractive index in the direction where the refractive index in the plane is maximum (ie, the slow axis direction), “ny” is the refractive index in the direction orthogonal to the slow axis in the plane (ie, the fast axis direction), and “nz” is the refractive index in the thickness direction.

[0038] (2) In-plane phase difference (Re)

[0039] "Re(λ)" is the in-plane phase difference measured by light of wavelength λnm at 23°C. For example, "Re(550)" is the in-plane phase difference measured by light of wavelength 550nm at 23°C. When the thickness of the layer (film) is set to d(nm), Re(λ) is calculated by the formula: Re(λ) = (nx-ny)×d.

[0040] (3) Retardation in the thickness direction (Rth)

[0041] "Rth(λ)" is the phase difference in the thickness direction measured by light of wavelength λnm at 23°C. For example, "Rth(550)" is the phase difference in the thickness direction measured by light of wavelength 550nm at 23°C. When the thickness of the layer (film) is set to d(nm), Rth(λ) is calculated by the formula: Rth(λ) = (nx-nz)×d.

[0042] (4) Nz coefficient

[0043] The Nz coefficient is obtained by Nz=Rth / Re.

[0044] (5) Angle

[0045] When an angle is mentioned in this specification, the angle includes both clockwise and counterclockwise relative to a reference direction. Therefore, for example, "45°" means ±45°.

[0046] A. Overall structure of optical laminate

[0047] Figure 1 1 is a schematic cross-sectional view of an optical laminate according to an embodiment of the present invention. The optical laminate 100 shown in the figure has a cover glass 30, a first adhesive layer 20, a polarizer 10, and a second adhesive layer 40 in sequence. Representatively, the optical laminate 100 is laminated on a liquid crystal panel 200 via the second adhesive layer 40. The optical laminate 100 shown in the figure has a through hole 15 that passes through the polarizer 10 and the second adhesive layer 40. In the example shown in the figure, the through hole 15 is filled with the first adhesive composition constituting the first adhesive layer 20. In the example shown in the figure, the polarizer 10 has a polarizer 11 and protective layers 12 and 13 laminated on both sides of the polarizer 11. Either of the protective layers 12 and 13 may be omitted. In one embodiment, the polarizer 10 has only a protective layer 12 laminated on the cover glass side of the polarizer 11. By omitting one protective layer, a thin optical laminate can be made. In a thin optical layered body, discoloration at the edge becomes conspicuous. However, according to the embodiment of the present invention, discoloration at the edge can be suppressed even when one protective layer is omitted.

[0048] As described above, in one embodiment, the optical laminate has a through hole. The through hole is arranged at any suitable position according to the purpose. Representatively, the through hole is arranged at the end of the optical laminate or near it. If it is such a structure, the influence on the image display can be set to the minimum limit. Only one through hole can be provided, or multiple through holes can be provided. For example, more than two through holes can also be provided. Even if the optical laminate of the embodiment of the present invention is provided with a through hole in the image display part, excessive discoloration of the end can be suppressed, and the reduction of image display performance can be suppressed.

[0049] The optical laminate may also be provided with an optical functional layer (not shown) other than the polarizer 10. As the optical functional layer, for example, a phase difference layer may be cited. The type, number, combination, configuration position, and characteristics of the optical functional layer may be appropriately set according to the purpose. In the case where the optical laminate has a phase difference layer, the phase difference layer may be configured, for example, between the polarizer 10 and the second adhesive layer 40.

[0050] The thickness of the optical laminate 100 can be set to any appropriate value. The total thickness of the polarizer 10 and the second adhesive layer 40 is preferably 120 μm to 400 μm, more preferably 130 μm to 300 μm, and further preferably 150 μm to 250 μm. If the total thickness of the polarizer 10 and the second adhesive layer 40 is within the above range, even if it is an optical laminate with a through hole, it is easy to fill the adhesive composition in the through hole. When the total thickness of the polarizer 10 and the second adhesive layer 40 is too thin, the operability is reduced during the manufacturing process of the image display device.

[0051] The thickness of the polarizer 10 can be set to any appropriate value. The thickness of the polarizer is preferably 45μm to 100μm, more preferably 45μm to 70μm, and further preferably 45μm to 60μm. As described above, in the case where the optical laminate has a through hole, the first adhesive layer can be provided in a manner to fill the through hole. In the case where the thickness of the first adhesive layer is desired to be thinned (the result is to thin the thickness of the optical laminate obtained), it is necessary to make the depth of the through hole shallower. Therefore, a thinner polarizer can be used as described above. As a polarizer of the thickness described above, a representative polarizer with a protective layer laminated only on one side of the polarizer is known. In the case of a polarizer with a protective layer laminated only on one side, the discoloration of the polarizer may be more problematic than that of a polarizer with a protective layer laminated on both sides of the polarizer. If the optical laminate of the embodiment of the present invention is used, even a polarizer of the thickness described above can suppress end discoloration.

[0052] Hereinafter, the components of the optical layered body will be described in detail.

[0053] B. Cover glass

[0054] The transmittance of the cover glass 30 at a wavelength of 243 nm is 7% to 50%. The transmittance of the cover glass at a wavelength of 243 nm is preferably 8% to 40%, more preferably 9% to 30%, and further preferably 10% to 25%. If the transmittance at a wavelength of 243 nm is within the above range, an optical laminate with suppressed end discoloration can be provided. When the transmittance at a wavelength of 243 nm exceeds 50%, the damage to the polarizer and the panel caused by sunlight may increase and the quality may be reduced. The transmittance of the cover glass at a wavelength of 243 nm can be measured by a spectrophotometer (for example, manufactured by Hitachi High-Tech Science Corporation, product name: U-4100). As long as the transmittance at a wavelength of 243 nm of the cover glass is 7% to 50%, any suitable thickness of the cover glass can be used.

[0055] The cover glass typically comprises silicon oxide (e.g., SiO 2) and aluminum oxide (Al 2 O 3 ), boron oxide (B 2 O 3 ), magnesium oxide (MgO), calcium oxide (CaO), strontium oxide (SrO), sodium oxide (Na 2 O), potassium oxide (K 2 O), iron oxide (Fe 2 O 3 ), titanium oxide (TiO 2 ) and other metal oxides. Any appropriate metal oxide can be used as the metal oxide other than silicon oxide according to the purpose. Only one metal oxide other than silicon oxide can be used alone or in combination of two or more metal oxides.

[0056] The cover glass preferably has a magnesium content of less than 0.5 atomic %, more preferably less than 0.4 atomic %, further preferably less than 0.3 atomic %, and particularly preferably less than 0.1 atomic %. By having a magnesium content of the cover glass in the above range, an optical laminate with suppressed end discoloration can be provided. The cover glass may also be substantially free of magnesium (for example, the element content is below the detection limit of the analysis device). The magnesium content of the cover glass can be measured using an X-ray photoelectron analyzer (ESCA (for example, manufactured by ULVAC-PHI, product name: Quantum 2000)).

[0057] In one embodiment, the cover glass preferably contains a metal oxide of an alkaline earth metal (hereinafter, also referred to as an alkaline earth metal oxide. When the alkaline earth metal oxide is contained, the durability of the cover glass is improved, and the devitrification temperature and viscosity during glass molding can be adjusted. In addition, the thermal expansion coefficient of the cover glass can be adjusted. Examples of the metal oxide of the alkaline earth metal include MgO, CaO, and SrO. The alkaline earth metal oxide may be used alone or in combination of two or more.

[0058] The alkaline earth metal oxide can be used in any suitable content. The content of the alkaline earth metal oxide in the cover glass (for example, the total content of MgO, CaO and SrO) is preferably 2% to 12% by weight. If the content of the alkaline earth metal oxide exceeds 12% by weight, the ultraviolet transmittance may decrease due to the increase in the devitrification temperature during molding and the increase in the strain of the Si-O bond contained in the glass.

[0059] The content of MgO is preferably 10% by weight or less in one embodiment, and preferably 0% by weight to 4% by weight in one embodiment. The content of CaO is preferably 10% by weight or less in one embodiment, and preferably 0% by weight to 9% by weight in one embodiment. The content of SrO is preferably 15% by weight or less in one embodiment, and preferably 0% by weight to 5% by weight in one embodiment. In an embodiment including alkaline earth metal oxides, it can be used as long as the total content of alkaline earth metal oxides is within the above range. In this specification, a content of 0% by weight includes a content below the detection limit of an analysis device.

[0060] The coverslip may also further contain TiO 2 and / or Fe 2 O 3 It is known that by including TiO 2 and / or Fe 2 O 3 , it is possible to adjust the ultraviolet transmittance (for example, the transmittance in the deep ultraviolet region). TiO 2 and Fe 2 O 3 The total content of is, for example, 0.0010 wt % or less. 2 and Fe 2 O 3 When the total content of is too large, there is a tendency for the ultraviolet transmittance to decrease.

[0061] C. Polarizer

[0062] C-1. Polarizer

[0063] The polarizer is typically composed of a resin film containing a dichroic substance (typically, iodine). As the resin film, any suitable resin film that can be used as a polarizer can be used. The resin film is typically a polyvinyl alcohol-based resin (hereinafter referred to as "PVA-based resin") film. The resin film can be a single-layer resin film or a laminate of two or more layers.

[0064] As a specific example of a polarizer composed of a single-layer resin film, a polarizer obtained by subjecting a PVA resin film to a dyeing treatment using iodine and a stretching treatment (representatively, uniaxial stretching) can be cited. The above-mentioned dyeing using iodine is performed, for example, by immersing the PVA resin film in an iodine aqueous solution. The stretching ratio of the above-mentioned uniaxial stretching is preferably 3 to 7 times. Stretching can be performed after the dyeing treatment, or it can be performed while dyeing. In addition, dyeing can also be performed after stretching. As needed, the PVA resin film is subjected to swelling treatment, cross-linking treatment, washing treatment, drying treatment, etc. For example, by immersing the PVA resin film in water for washing before dyeing, not only can the stains and anti-blocking agents on the surface of the PVA resin film be washed away, but the PVA resin film can also be swelled to prevent uneven dyeing.

[0065] As a specific example of a polarizer obtained using a laminate, there can be cited a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate. The polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate can be made, for example, in the following manner: a PVA-based resin solution is applied to a resin substrate, dried to form a PVA-based resin layer on the resin substrate, and a laminate of the resin substrate and the PVA-based resin layer is obtained; the laminate is stretched and dyed to make the PVA-based resin layer into a polarizer. In this embodiment, it is preferred to form a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin on one side of the resin substrate. Stretching typically includes immersing the laminate in a boric acid aqueous solution for stretching. Furthermore, stretching may further include stretching the laminate in the air at a high temperature (for example, above 95°C) before stretching in a boric acid aqueous solution as required. In addition, in the present embodiment, it is preferred that the laminate is provided with a drying shrinkage treatment in which the laminate shrinks by more than 2% in the width direction by heating while conveying in the length direction. Representatively, the manufacturing method of the present embodiment includes sequentially performing an air auxiliary stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment on the laminate. By introducing auxiliary stretching, even when PVA is coated on a thermoplastic resin, the crystallinity of PVA can be improved, and high optical properties can be achieved. In addition, by simultaneously improving the orientation of PVA in advance, when immersed in water in a subsequent dyeing process or a stretching process, problems such as a decrease in the orientation of PVA and dissolution can be prevented, and high optical properties can be achieved. Furthermore, when the PVA-based resin layer is immersed in a liquid, the disorder of the orientation of the polyvinyl alcohol molecules and the decrease in the orientation can be suppressed compared to the case where the PVA-based resin layer does not contain a halide. Thus, the optical properties of the polarizer obtained by the treatment process of immersing the laminate in a liquid such as a dyeing treatment and an underwater stretching treatment can be improved. Furthermore, by shrinking the laminate in the width direction using a drying shrinkage treatment, the optical properties can be improved. The obtained laminate of resin substrate / polarizer can be used directly (that is, resin substrate can also be used as a protective layer of polarizer), or resin substrate can be peeled off from the laminate of resin substrate / polarizer, and any suitable protective layer corresponding to the purpose can be stacked on the peeling surface. The details of the manufacture method of such polarizer are, for example, recorded in Japanese Patent Publication No. 2012-73580 (Japanese Patent No. 5414738) and Japanese Patent No. 6470455. The overall records of these publications are cited in this specification as a reference.

[0066] In one embodiment, the polarizer further comprises boric acid. The boric acid content of the polarizer is preferably 10% by weight or more, more preferably 13% by weight to 25% by weight. If the boric acid content of the polarizer is in such a range, the ease of curling adjustment during lamination can be well maintained through a synergistic effect with the iodine content described later, and the curling during heating can be well suppressed, while improving the durability of the appearance during heating. The boric acid content can be calculated, for example, by the neutralization method using the following formula as the amount of boric acid contained in the polarizer per unit weight.

[0067] [Mathematical formula 1]

[0068]

[0069] The iodine content of the polarizer is preferably 2% by weight or more, more preferably 2% to 10% by weight. If the iodine content of the polarizer is within this range, the synergistic effect with the boric acid content can well maintain the ease of curling adjustment during lamination, well suppress curling during heating, and improve the durability of the appearance during heating. In this specification, "iodine content" refers to the total amount of iodine contained in the polarizer (PVA-based resin film). More specifically, iodine is present in the polarizer in the form of iodide ions (I - ), iodine molecule (I 2 ), polyiodide ion (I 3 - ,I 5 - ) and other forms, and the iodine content in this specification refers to the amount of iodine including all of these forms. The iodine content can be calculated, for example, by the standard curve method of fluorescent X-ray analysis. It should be noted that the polyiodide ion exists in the polarizer in the form of a PVA-iodine complex. By forming such a complex, absorption dichroism can be exhibited in the wavelength range of visible light. Specifically, the complex of PVA and triiodide ion (PVA·I 3 - ) has an absorption peak near 470nm, and the complex of PVA and pentaiodide ion (PVA·I 5 - ) has an absorption peak near 600nm. As a result, polyiodide ions can absorb light in a wide range of visible light depending on their form. On the other hand, iodide ions (I - ) has an absorption peak near 230nm and does not substantially participate in the absorption of visible light. Therefore, the polyiodide ion existing in the state of a complex with PVA can mainly participate in the absorption performance of the polarizer.

[0070] The polarizer preferably shows absorption dichroism at any wavelength of 380nm to 780nm. The single transmittance Ts of the polarizer is preferably 40% to 48%, more preferably 41% to 46%. The polarization degree P of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and further preferably 99.9% or more. The above-mentioned single transmittance is representatively a Y value measured using an ultraviolet visible spectrophotometer and corrected for visibility. The above-mentioned polarization degree is representatively obtained by the following formula based on the parallel transmittance Tp and the orthogonal transmittance Tc obtained by measuring using an ultraviolet visible spectrophotometer and correcting for visibility.

[0071] Polarization degree (%) = {(Tp-Tc) / (Tp+Tc)} 1 / 2 ×100

[0072] The thickness of the polarizer can be set to any appropriate value. For example, the thickness of the polarizer is preferably 15 μm or less, more preferably 1 μm to 12 μm, further preferably 2 μm to 10 μm, and particularly preferably 3 μm to 8 μm.

[0073] C-2. Protective layer

[0074] The protective layer is formed by any suitable film that can be used as the protective layer of the polarizer. As the specific example of the material that becomes the main component of this film, cellulose resins such as triacetyl cellulose (TAC), polyester, polyvinyl alcohol, polycarbonate, polyamide, polyimide, polyether sulfone, polysulfone, polystyrene, polynorbornene, polyolefin, (methyl) acrylic acid, acetate and other transparent resins can be listed. In addition, thermosetting resins or ultraviolet curing resins such as (methyl) acrylic acid, carbamate, (methyl) acrylic acid carbamate, epoxy, silicone can also be listed. In addition, glassy polymers such as siloxane polymers can also be listed. In addition, the polymer film recorded in Japanese Patent Publication No. 2001-343529 (WO01 / 37007) can also be used. As the material of the film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group on the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group on the side chain can be used, for example, a resin composition containing an alternating copolymer formed by isobutylene and N-methylmaleimide and an acrylonitrile-styrene copolymer can be cited. The polymer film can be, for example, an extrusion molding of the above resin composition.

[0075] The outer protective layer (protective layer 12 in the example shown in the figure) may be subjected to surface treatment such as hard coating treatment, anti-reflection treatment, anti-blocking treatment, anti-glare treatment, etc. as required.

[0076] The inner protective layer is preferably optically isotropic. In the present specification, “optically isotropic” means that the in-plane retardation Re(550) is 0 nm to 10 nm, and the thickness direction retardation Rth(550) is -10 nm to +10 nm.

[0077] The thickness of the protective layer may be any appropriate thickness. The thickness of the protective layer is, for example, 15 μm to 45 μm, preferably 20 μm to 40 μm. It should be noted that, when surface treatment is performed, the thickness of the protective layer includes the thickness of the surface treatment layer.

[0078] The phase difference layer is typically provided to impart anti-reflection properties to the polarizing plate, and can function as a λ / 4 plate when the phase difference layer is a single layer. The phase difference layer is preferably an orientation fixing layer of a liquid crystal compound. The in-plane phase difference Re (550) of the phase difference layer is preferably greater than 100 nm and less than 160 nm, more preferably 110 nm to 155 nm, and further preferably 130 nm to less than 150 nm.

[0079] When the retardation layer is composed of a single layer, the thickness is preferably 0.5 μm to 7 μm, more preferably 1 μm to 5 μm. By using a liquid crystal compound, an in-plane retardation equivalent to that of a resin film can be achieved with a thickness significantly thinner than that of a resin film.

[0080] The Nz coefficient of the retardation layer is preferably 0.9 to 1.5, and more preferably 0.9 to 1.3. When such a relationship is satisfied, when the obtained optical layered body is used in an image display device, a very excellent reflection hue can be achieved.

[0081] The phase difference layer can show a reverse dispersion wavelength characteristic in which the phase difference value increases correspondingly with the wavelength of the measuring light, or a positive wavelength dispersion characteristic in which the phase difference value decreases correspondingly with the wavelength of the measuring light, or a flat wavelength dispersion characteristic in which the phase difference value does not change substantially according to the wavelength of the measuring light. In one embodiment, the phase difference layer shows a reverse dispersion wavelength characteristic. In this case, the Re(450) / Re(550) of the phase difference layer is preferably less than 1, more preferably greater than 0.8 and less than 1, and further preferably greater than 0.8 and less than 0.95. In addition, the Re(550) / Re(650) of the phase difference layer is preferably greater than 1, more preferably greater than 1 and less than 1.2, and further preferably 1.01 to 1.15. If it is such a structure, it is possible to achieve very excellent anti-reflection properties.

[0082] The angle between the slow axis of the phase difference layer and the absorption axis of the polarizer is preferably 40° to 50°, more preferably 42° to 48°, and further preferably about 45°. If the angle is in such a range, an optical laminate having very excellent circular polarization properties (and, as a result, very excellent anti-reflection properties) can be obtained by setting the phase difference layer to a λ / 4 plate as described above.

[0083] The phase difference layer is preferably an orientation fixed layer of a liquid crystal compound. By using a liquid crystal compound, the difference between nx and ny of the obtained phase difference layer can be made particularly large compared to non-liquid crystal materials, so the thickness of the phase difference layer used to obtain the desired in-plane phase difference can be particularly reduced. As a result, it is possible to further thin the polarizer with a phase difference layer. In this specification, the "liquid crystal orientation fixed layer" refers to a layer in which the liquid crystal compound is oriented in a specified direction within the layer and its orientation state is fixed. It should be noted that the "orientation fixed layer" is a concept that includes an orientation solidified layer obtained by solidifying the liquid crystal monomer as described below.

[0084] The optical laminate 100 may further include other phase difference layers. The other phase difference layers may be so-called positive C plates whose refractive index characteristics show the relationship of nz>nx=ny. By using a positive C plate as the other phase difference layer, reflection in the inclined direction can be well prevented, and a wide viewing angle of the anti-reflection function becomes possible. In this case, the phase difference Rth(550) in the thickness direction of the other phase difference layer is preferably -50nm to -300nm, more preferably -70nm to -250nm, further preferably -90nm to -200nm, and particularly preferably -100nm to -180nm. Here, "nx=ny" includes not only the case where nx and ny are strictly equal, but also the case where nx and ny are substantially equal. That is, the in-plane phase difference Re(550) of the other phase difference layer may be less than 10nm.

[0085] Other phase difference layers having a refractive index characteristic of nz>nx=ny can be formed by any suitable material. Other phase difference layers are preferably formed by a film containing a liquid crystal material fixed in a vertical orientation. The vertically oriented liquid crystal material (liquid crystal compound) can be a liquid crystal monomer or a liquid crystal polymer. As specific examples of the liquid crystal compound and the method for forming the phase difference layer, the liquid crystal compound and the method for forming the phase difference layer described in

[0020] to

[0028] of Japanese Patent Gazette No. 2002-333642 can be cited. In this case, the thickness of the other phase difference layer is preferably 0.5μm to 10μm, more preferably 0.5μm to 8μm, and further preferably 0.5μm to 5μm.

[0086] D. 1st adhesive layer

[0087] The first adhesive layer is composed of a first adhesive composition as an ultraviolet curing adhesive. Since the first adhesive layer is composed of an ultraviolet curing adhesive, even when the thickness of the first adhesive layer is thin, the cover glass and the polarizer can be fully adhered. The ultraviolet curing adhesive typically includes a base polymer and a photopolymerization initiator. As the first adhesive composition, any suitable ultraviolet curing adhesive can be used.

[0088] The storage elastic modulus of the first adhesive composition at 60°C before curing is preferably 1.0×10 5 Pa or less, more preferably 1.0×10 3 Pa~1.0×10 5 Pa, more preferably 5.0×10 3 Pa~8.0×10 4 Pa, particularly preferably 7.5×10 3 Pa~6.0×10 4 Pa. If the storage elastic modulus of the first adhesive composition before curing is within such a range, the first adhesive composition exhibits suitable deformation behavior (viscoelastic behavior), and even when the polarizer has a through hole, it can flow well into the end of the through hole, and the gap between the adhesive layer and the through hole can be suppressed. The storage elastic modulus of the first adhesive composition at 60°C after curing is preferably 5.0×10 3 Pa~5.0×10 5 Pa, more preferably 7.5×10 3 Pa~4.0×10 5 Pa, more preferably 8.0×10 3 Pa~3.0×10 5 Pa.

[0089] The total light transmittance of the first pressure-sensitive adhesive layer is preferably 85% or more, and more preferably 90% or more. The haze value of the first pressure-sensitive adhesive layer is preferably 1.5% or less, and more preferably 1.0% or less.

[0090] The thickness of the first adhesive layer can be set to any appropriate value. The thickness of the first adhesive layer is preferably 50 μm to 500 μm, more preferably 50 μm to 300 μm, and even more preferably 75 μm to 200 μm.

[0091] D-1. Base polymer

[0092] As the base polymer of the first adhesive composition, any suitable polymer can be used. For example, rubber polymers such as (meth) acrylic acid polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, vinyl acetate / vinyl chloride copolymers, modified polyolefins, epoxy polymers, fluorine polymers, natural rubber, synthetic rubbers can be listed. It is preferred to use a (meth) acrylic acid adhesive composition comprising a (meth) acrylic acid polymer as a base polymer. Because the optical transparency is excellent, it demonstrates the bonding characteristics such as appropriate wettability, cohesiveness and adhesion, and weather resistance and heat resistance are also excellent. In this specification, "(meth) acrylic acid" refers to acrylic acid and / or methacrylic acid.

[0093] D-1-1. (Meth)acrylic base polymer

[0094] The (meth) acrylic base polymer is obtained by polymerizing any suitable monomer component. The acrylic base polymer preferably uses an amide-containing monomer as a monomer component. By using an amide-containing monomer as a monomer component, a base polymer having an amide skeleton can be obtained. By the first adhesive composition comprising an amide-containing monomer and a base polymer having an amide skeleton, the adhesion between the cover glass and the polarizer can be improved. As the amide-containing monomer, any suitable monomer can be used. Examples of the amide group-containing monomer include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropylacrylamide, N-methyl(meth)acrylamide, N-butyl(meth)acrylamide, N-hexyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methylol-N-propane(meth)acrylamide, aminomethyl(meth)acrylamide, aminoethyl(meth)acrylamide, mercaptomethyl(meth)acrylamide, mercaptoethyl(meth)acrylamide, and other acrylamide monomers; N-(meth)acryloylmorpholine, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, and other N-vinyl lactam-containing monomers. The amide group-containing monomer may be used alone or in combination of two or more.

[0095] The content of the amide group-containing monomer relative to the total amount of the monomer components constituting the (meth)acrylic base polymer is preferably 1 wt% to 10 wt%, more preferably 2 wt% to 5 wt%. When the content of the amide group-containing monomer is within the above range, the adhesion between the cover glass and the polarizer can be improved.

[0096] The first adhesive composition contains an alkyl (meth)acrylate as a main monomer component. As the alkyl (meth)acrylate, an alkyl (meth)acrylate having an alkyl group with a carbon number of 1 to 20 is preferably used. The alkyl group of the alkyl (meth)acrylate may be linear, branched, or cyclic. The amount of the alkyl (meth)acrylate is preferably 40% by weight or more, more preferably 50% by weight or more, and further preferably 60% by weight or more relative to the total amount of the monomer components constituting the (meth)acrylic base polymer. The alkyl (meth)acrylate is used, for example, in such a manner that the total amount of the monomer components is 100% by weight. From the viewpoint of setting the glass transition temperature (Tg) of the polymer chain to an appropriate range, the amount of the alkyl (meth)acrylate having a linear alkyl group with a carbon number of 4 to 10 is preferably 30% by weight or more, more preferably 40% by weight or more, and further preferably 45% by weight or more relative to the total amount of the monomer components constituting the (meth)acrylic base polymer.

[0097] The (meth) acrylic acid base polymer preferably further comprises a monomer component with a crosslinkable functional group. As the monomer component with a crosslinkable functional group, for example, a hydroxyl-containing monomer and a carboxyl-containing monomer can be cited. When a crosslinking structure is introduced by an isocyanate-based crosslinking agent, the hydroxyl group becomes a reaction point with an isocyanate group, and when a crosslinking structure is introduced by an epoxy-based crosslinking agent, the carboxyl group becomes a reaction point with an epoxy group. It is preferred to use a hydroxyl-containing monomer as a monomer component with a crosslinkable functional group, and to introduce a crosslinking structure by an isocyanate-based crosslinking agent. If it is such a structure, the crosslinking property of the base polymer is improved, and a high transparency adhesive layer can be formed. And then, if it is such a structure, a so-called acid-free adhesive can be achieved.

[0098] The amount of the hydroxyl-containing monomer is preferably 5% to 30% by weight, more preferably 8% to 25% by weight, and further preferably 10% to 20% by weight relative to the total amount of the monomer components constituting the (meth) acrylic base polymer. If the amount of the hydroxyl-containing monomer is within such a range, the degree of crosslinking (gel fraction) can be increased with a small amount of crosslinking, and as a result, the filling property and operability of the first adhesive composition before curing into the through-hole can be improved.

[0099] The (meth)acrylic base polymer may further contain any suitable monomer component according to the purpose. Specific examples include anhydride-containing monomers, caprolactone adducts of (meth)acrylic acid, sulfonic acid-containing monomers, phosphoric acid-containing monomers, vinyl acetate, vinyl propionate, styrene, α-methylstyrene and other vinyl monomers; acrylonitrile, methacrylonitrile and other cyano-containing acrylic monomers; (meth)glycidyl acrylate and other epoxy-containing monomers; (meth)polyethylene glycol, (meth)polypropylene glycol, (meth)methoxyethylene glycol, (meth)methoxypolypropylene glycol and other glycol-based acrylate monomers; (meth)tetrahydrofurfuryl acrylate, fluoro(meth)acrylate, silicone (meth)acrylate, 2-methoxyethyl (meth)acrylate and other acrylate monomers.

[0100] By polymerizing the above-mentioned monomer components by any appropriate method, a (meth)acrylic base polymer can be obtained. For example, various free radical polymerizations such as solution polymerization, UV polymerization and other active energy ray polymerization, bulk polymerization, emulsion polymerization, etc. can be listed. As polymerization conditions, any appropriate polymerization conditions can be adopted within the scope that does not damage the effect of the present invention. When the monomer components are polymerized, any other appropriate components other than the monomer components can also be included. As other components, for example, polymerization initiators, chain transfer agents, solvents, etc. can be listed. The content of these other components can adopt any appropriate content within the scope that does not damage the effect of the present invention.

[0101] The polymerization initiator used for polymerization of the base polymer may be a thermal polymerization initiator, a photopolymerization initiator (photoinitiator), or the like, depending on the type of polymerization reaction. The polymerization initiator may be one type or two or more types.

[0102] In one embodiment, as a polymerization initiator, for example, an azo polymerization initiator, a peroxide polymerization initiator (for example, dibenzoyl peroxide, tert-butyl permaleate, etc.), a redox polymerization initiator, etc. are used. Preferably, an azo polymerization initiator is used. By using an azo polymerization initiator, it is possible to prevent the decomposition product of the polymerization initiator from remaining in the (meth) acrylic acid base polymer as a part of the generation cause of the heating generated gas (exhaust). As an azo polymerization initiator, 2,2'-azobis(2,4-dimethylvaleronitrile) (ADVN), 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis-2-methylbutyronitrile (AMBN), 2,2'-azobis(2-methylpropionic acid) dimethyl ester, 4,4'-azobis-4-cyanovaleric acid, etc. can be listed.

[0103] In one embodiment, the first adhesive composition preferably includes a base polymer into which a cross-linked structure is introduced as a (meth)acrylic base polymer. The polymer into which a cross-linked structure is introduced in the (meth)acrylic base polymer can be obtained, for example, by the following methods: (1) a method of polymerizing a (meth)acrylic polymer having a functional group that can react with a cross-linking agent, adding a cross-linking agent, and reacting the (meth)acrylic polymer with the cross-linking agent; and (2) a method of introducing a branched structure (cross-linked structure) in a polymer chain by including a multifunctional compound in the polymer component. These can also be used in combination.

[0104] As the specific example of the crosslinking agent in the method for reacting the base polymer with the crosslinking agent of the above-mentioned (1), isocyanate crosslinking agents, epoxy crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, carbodiimide crosslinking agents, metal chelate crosslinking agents, etc. can be listed. Among them, from the aspect of high reactivity with the hydroxyl and carboxyl of the base polymer and easy introduction of the crosslinked structure, isocyanate crosslinking agents and epoxy crosslinking agents are preferred. These crosslinking agents react with the functional groups such as the hydroxyl and carboxyl introduced into the base polymer to form a crosslinked structure. As mentioned above, in the case where the base polymer adopts an acid-free adhesive that does not contain a carboxyl group, it is preferred to introduce the crosslinked structure through the hydroxyl and isocyanate crosslinking agents in the base polymer.

[0105] The crosslinking agent is preferably used in an amount of 0.03 to 0.5 parts by weight, more preferably 0.05 to 0.3 parts by weight, further preferably 0.06 to 0.25 parts by weight, and particularly preferably 0.07 to 0.2 parts by weight relative to 100 parts by weight of the base polymer. By setting the amount of the crosslinking agent used to such a range, the gel fraction can be set to the above-described desired range.

[0106] In the method of (2) above in which a polyfunctional compound is included in the polymerization components of the base polymer, the total amount of the monomer components constituting the (meth)acrylic base polymer and the polyfunctional compound used to introduce the cross-linking structure can be reacted at once, or the polymerization can be carried out in multiple stages. As a method of carrying out polymerization in multiple stages, the following method is preferred: the monofunctional monomers constituting the (meth)acrylic base polymer are polymerized (prepolymerized) to prepare a partial polymer (prepolymer composition), a polyfunctional compound such as a polyfunctional (meth)acrylate is added to the prepolymer composition, and the prepolymer composition and the polyfunctional monomer are polymerized (formal polymerization). The prepolymer composition is a partial polymer containing a polymer with a low degree of polymerization and unreacted monomers.

[0107] By prepolymerizing the constituents of the (meth) acrylic acid base polymer, the branching points (crosslinking points) based on the multifunctional compound can be uniformly introduced into the (meth) acrylic acid base polymer. In addition, after a mixture of a low molecular weight polymer or a partial polymer and an unpolymerized monomer component (adhesive composition) is applied to a substrate, formal polymerization is performed on the substrate to form an adhesive layer. Low polymer compositions such as prepolymer compositions are low in viscosity and excellent in coating properties. Therefore, if a method of performing formal polymerization on a substrate after applying a mixture of a prepolymer composition and a multifunctional compound, i.e., an adhesive composition, is utilized, the productivity of the adhesive layer can be improved, and the thickness of the adhesive layer can be made uniform.

[0108] As the multifunctional compound for introducing the cross-linked structure, there can be cited compounds containing two or more polymerizable functional groups (ethylenically unsaturated groups) having unsaturated double bonds in one molecule. The multifunctional compound is typically a photopolymerizable multifunctional compound. As the multifunctional compound, multifunctional (meth)acrylates are preferred from the perspective of easy copolymerization with the monomer components of the (meth)acrylic polymer. Any suitable multifunctional (meth)acrylate can be used as the multifunctional (meth)acrylate. For example, 1,6-hexanediol di(meth)acrylate, butanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, allyl (meth)acrylate, and vinyl (meth)acrylate are mentioned. When a branched (crosslinked) structure is introduced by active energy ray polymerization (photopolymerization), a polyfunctional (meth)acrylate is preferred.

[0109] The molecular weight of the polyfunctional compound is preferably 1500 or less, more preferably 1000 or less. The lower limit of the molecular weight may be, for example, 500. The functional group equivalent (g / eq) of the polyfunctional compound is preferably 50 to 500, more preferably 70 to 300, and further preferably 80 to 200. With such a configuration, the viscoelasticity of the first adhesive composition can be appropriately adjusted.

[0110] The polyfunctional compound is preferably used in a ratio of 1 to 6 parts by weight, more preferably 2 to 5 parts by weight, and further preferably 2.5 to 4 parts by weight relative to 100 parts by weight of the base polymer. If the amount used is too little, the adhesion retention of the first adhesive composition (the result is the first adhesive layer) sometimes becomes insufficient. If the amount used is too much, the first adhesive layer formed sometimes becomes too hard, and the impact resistance becomes insufficient. And then, the processability and / or processing dimensional stability of the first adhesive composition sometimes become insufficient.

[0111] In one embodiment, the polyfunctional compound is preferably a compound containing three or more photopolymerizable functional groups in one molecule, and more preferably a (meth)acrylate containing three or more photopolymerizable functional groups in one molecule. By using a trifunctional or higher photopolymerizable compound, the adhesive retention of the first adhesive composition (as a result, the first adhesive layer) can be further improved. A bifunctional photopolymerizable compound and a trifunctional or higher photopolymerizable compound can also be used in combination. The trifunctional or higher photopolymerizable compound is preferably used in a ratio of 0.5 to 5 parts by weight, more preferably 1 to 4.5 parts by weight, and further preferably 2 to 4 parts by weight relative to 100 parts by weight of the base polymer.

[0112] The adhesive composition (first adhesive composition) may contain a photopolymerization initiator, a silane coupling agent, and any appropriate additives depending on the purpose, in addition to the above-mentioned base polymer, crosslinking agent, and polyfunctional compound.

[0113] As the photopolymerization initiator, for example, acylphosphine oxide photopolymerization initiator, alkylphenone photopolymerization initiator, benzoin ether photopolymerization initiator, acetophenone photopolymerization initiator, α-ketol photopolymerization initiator, aromatic sulfonyl chloride photopolymerization initiator, photoactive oxime photopolymerization initiator, benzoin photopolymerization initiator, benzyl photopolymerization initiator, benzophenone photopolymerization initiator, ketal photopolymerization initiator, thioxanthone photopolymerization initiator, etc. can be listed. Preferably, acylphosphine oxide photopolymerization initiator is used. By using acylphosphine oxide photopolymerization initiator as the photopolymerization initiator, it is possible to provide an ultraviolet curable adhesive composition having excellent internal curability even in the case of a thick adhesive layer with a photobleaching effect that disappears after absorption by light reaction. In addition, since it is not easy to cause yellowing, it is possible to provide an adhesive composition that can form an adhesive layer with excellent transparency. Photopolymerization initiator can be used only one kind, or two or more kinds can be used in combination.

[0114] Examples of the acylphosphine oxide-based photopolymerization initiator include bis(2,6-dimethoxybenzoyl)phenylphosphine oxide, bis(2,6-dimethoxybenzoyl) (2,4,4-trimethylpentyl) phosphine oxide, bis(2,6-dimethoxybenzoyl)-n-butylphosphine oxide, bis(2,6-dimethoxybenzoyl)-(2-methylpropane-1-yl) phosphine oxide, bis(2,6-dimethoxybenzoyl)-(1-methylpropane-1-yl) phosphine oxide, bis(2,6-dimethoxybenzoyl)-tert-butylphosphine oxide, bis(2,6-dimethoxybenzoyl)cyclohexylphosphine oxide, bis(2,6-dimethoxybenzoyl)octylphosphine oxide, bis(2-methoxybenzoyl) (2-methylpropane-1-yl) phosphine oxide, bis(2,6-dimethoxybenzoyl)(1-methylpropane-1-yl)phosphine oxide, bis(2-methoxybenzoyl)(1-methylpropane-1-yl)phosphine oxide, bis(2,6-diethoxybenzoyl)(2-methylpropane-1-yl)phosphine oxide, bis(2,6-diethoxybenzoyl)(1-methylpropane-1-yl)phosphine oxide, bis(2,6-dibutoxybenzoyl)(2-methylpropane-1-yl)phosphine oxide, bis(2,4-dimethoxybenzoyl)(2-methylpropane-1-yl)phosphine oxide, bis(2,4,6-trimethylbenzoyl)(2,4-dipentyloxyphenyl)phosphine oxide, bis(2,6-dimethoxybenzoyl)benzylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2-phenylpropylphosphine oxide, bis(2, bis(2,6-dimethoxybenzoyl)-2-phenylethylphosphine oxide, bis(2,6-dimethoxybenzoyl)benzylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2-phenylpropylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2-phenylethylphosphine oxide, 2,6-dimethoxybenzoylbenzylbutylphosphine oxide, 2,6-dimethoxybenzoylbenzyloctylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,5-diisopropylphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2-methylphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-4-methylphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,5-diethylphenylphosphine oxide 2,4,6-trimethylbenzoyl)-2,3,5,6-tetramethylphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,4-di-n-butoxyphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, bis(2,4,6-trimethylbenzoyl)isobutylphosphine oxide, 2,6-dimethoxybenzoyl-2,4,6-trimethylbenzoyl-n-butylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,4-di-butoxyphenylphosphine oxide, 1,10-bis[bis(2,4,6-trimethylbenzoyl)phosphine oxide] decane, tri(2-methylbenzoyl)phosphine oxide, etc.

[0115] Examples of commercially available acylphosphine oxide-based photopolymerization initiators include Omnirad 819 (bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, manufactured by IGM RESINS BV) and Omnirad TPO (2,4,6-trimethylbenzoyldiphenylphosphine oxide, manufactured by IG RESINS BV).

[0116] The content of the photopolymerization initiator in the first adhesive composition is preferably 0.01 to 5 parts by weight, more preferably 0.05 to 3 parts by weight, based on 100 parts by weight of the base polymer.

[0117] As the silane coupling agent, any suitable silane coupling agent can be used. By using a silane coupling agent, the adhesive force of the first adhesive composition can be adjusted. The content of the silane coupling agent in the adhesive composition is preferably 0.01 to 5 parts by weight, more preferably 0.03 to 2 parts by weight, relative to 100 parts by weight of the base polymer.

[0118] As additives, any suitable additives can be used. As specific examples of additives, antioxidants, antistatic agents, rework enhancers, colorants, pigments, dyes, surfactants, plasticizers, adhesive agents, surface lubricants, leveling agents, softeners, anti-aging agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors, conductive agents, inorganic or organic fillers, metal powders, particles, foils can be listed. In addition, a redox system with a reducing agent can also be used within a controllable range. The type, number, combination, and amount of additives can be appropriately set according to the purpose.

[0119] In one embodiment, the first adhesive composition comprises an amide-containing monomer as a monomer component, and an acylphosphine oxide-based photopolymerization initiator is used as a photopolymerization initiator. The first adhesive composition of this embodiment can further improve the adhesion between the cover glass and the polarizer. On the other hand, in the case of a photochemical laminated body for a polarizer having a through hole, excessive discoloration sometimes occurs at the end of the polarizer (particularly the end of the through hole). This excessive discoloration is different from the discoloration of a conventional polarizer, and can be caused by absorption in the high wavelength region (by I 5 - The optical laminate of the embodiment of the present invention uses a cover glass with a transmittance of 7% to 50% at a wavelength of 243nm as a cover glass. By using such a cover glass in combination, it is possible to prevent end discoloration, especially excessive discoloration at the end of the through hole of the polarizing plate having a through hole.

[0120] E. Second adhesive layer

[0121] The second adhesive layer is typically used for laminating the optical laminate with other components of the image display device such as the liquid crystal cell. As the adhesive composition forming the second adhesive layer, any suitable adhesive can be used. Typically, an acrylic adhesive is used. For example, by adjusting the monomer composition of the base polymer, the adhesive can also adjust the properties.

[0122] The thickness of the second adhesive layer is preferably 50 μm or less, more preferably 40 μm or less, further preferably 30 μm or less, and particularly preferably 25 μm or less. The thickness of the second adhesive layer can be, for example, 2 μm or more. If the thickness of the second adhesive layer is in such a range, it can contribute to the thinning of the image display device. If the thickness of the second adhesive layer is in such a range, it becomes easy to fill the through hole with the adhesive composition constituting the first adhesive layer. More specifically, since the depth of the through hole becomes smaller, it becomes easy to fill with an adhesive. As a result, the gap in the through hole can be reduced.

[0123] F. Method for producing an optical laminate

[0124] The optical laminate of the embodiment of the present invention can be made by any suitable manufacturing method. For example, the second adhesive layer is formed by applying the second adhesive composition on one side of the polarizer, and then the first adhesive layer is formed by applying the first adhesive composition on the other side of the polarizer, and then the cover glass is laminated on the polarizer via the first adhesive layer to obtain the optical laminate. The first adhesive layer and the second adhesive layer can also be transferred to a material having an adhesive layer formed on a release liner.

[0125] In one embodiment, the optical laminate has a through hole. In this embodiment, the first adhesive layer can be formed by applying the first adhesive layer so that the first adhesive composition flows into the through hole. In addition, the cover glass having the adhesive layer forming the first adhesive layer transferred thereto can be laminated to a polarizer, for example, by vacuum lamination to produce the optical laminate.

[0126] G. Image display device

[0127] The image display device of an embodiment of the present invention includes the above-mentioned optical laminate. In one embodiment, the optical laminate includes a polarizer having a through hole. In one embodiment, the through hole corresponds to the camera portion of the image display device. As described above, the optical laminate of an embodiment of the present invention can prevent excessive discoloration of the end portion even when it has a through hole. In the image display device, the camera portion is sometimes provided in the image display portion. If the image display device of an embodiment of the present invention is utilized, even when there is a through hole in the image display portion, an adverse effect on the display performance of the image display device can be prevented.

[0128] Example

[0129] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. The measuring methods of the various properties in the examples are as follows.

[0130] (1) Thickness

[0131] The thickness of 10 μm or less was measured using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd., product name "MCPD-3000"), and the thickness exceeding 10 μm was measured using a digital micrometer (manufactured by ANRITSU Co., Ltd., product name "KC-351C").

[0132] (2) Transmittance at a wavelength of 243 nm

[0133] The transmittance of the cover glass used in Examples and Comparative Examples at a wavelength of 243 nm was measured using a spectrophotometer (manufactured by Hitachi High-Tech Science Corporation, product name: U-4100). The transmittance was measured in the thickness direction of the cover glass.

[0134] (3) Element determination of cover glass

[0135] The element contents of the cover glasses used in Examples and Comparative Examples were measured using an X-ray photoelectron analyzer (ESCA (manufactured by ULVAC, trade name: Quantum 2000)).

[0136] (4) Excessive decolorization

[0137] The optical laminate obtained in the embodiment and the comparative example was placed under the conditions of 60°C and 90% RH for 240 hours and subjected to a humidification reliability test. Afterwards, a spectrophotometer (manufactured by Hitachi High-Tech Science Corporation, product name: U-4100) was used to measure the orthogonal transmittance at a wavelength of 505nm and the orthogonal transmittance at a wavelength of 610nm for the portion of the optical laminate that was 150μm away from the end of the through hole. The case where the bleached portion had an orthogonal transmittance at a wavelength of 610nm greater than the orthogonal transmittance at a wavelength of 505nm was set as having excessive bleaching, and the case where there was no bleached portion where the orthogonal transmittance at a wavelength of 610nm around the end of the through hole was greater than the orthogonal transmittance at a wavelength of 505nm was set as having no excessive bleaching.

[0138] <Manufacturing Example 1: Preparation of Adhesive Constituting Second Adhesive Layer>

[0139] A monomer mixture containing 99 parts by weight of butyl acrylate (BA) and 1 part by weight of 4-hydroxybutyl acrylate (4HBA) was added to a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet tube, and a cooler. Furthermore, 0.1 parts by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator was added together with 100 parts by weight of ethyl acetate relative to 100 parts by weight of the monomer mixture (solid content), and nitrogen was introduced while slowly stirring to replace the nitrogen, and then the liquid temperature in the flask was maintained at around 55°C and a polymerization reaction was performed for 8 hours to prepare a solution of an acrylic polymer. With respect to 100 parts by weight of the solid content of the obtained acrylic polymer solution, 0.3 parts by weight of benzoyl peroxide (trade name “NYPER BMT 40SV” manufactured by NOF Corporation) as a crosslinking agent, 0.2 parts by weight of an isocyanate crosslinking agent (trade name “Takenate D110N” manufactured by Mitsui Chemicals, Inc.), 0.03 parts by weight of a rework enhancing agent (trade name “SILYL SAT10” manufactured by KANEKA Corporation), 7 parts by weight of an antistatic agent (trade name “LiTFSi30EA” manufactured by Mitsubishi Materials Co., Ltd.), 0.3 parts by weight of an antioxidant (trade name “Irganox 1010” manufactured by BASF Japan, a hindered phenol-based agent), and 0.2 parts by weight of a silane coupling agent (trade name: A-100, manufactured by Soken Chemical Co., Ltd., an acetoacetyl group-containing silane coupling agent) were added to obtain an adhesive composition A.

[0140] <Manufacturing Example 2: Preparation of Adhesive Sheet B Having First Adhesive Layer>

[0141] Add 2-ethylhexyl acrylate (2EHA), 2-hydroxyethyl acrylate (HEA), and methacrylamide to a 2L volumetric flask, dilute with a diluent solvent containing methyl ethyl ketone and ethyl acrylate, and adjust in a manner that the total weight becomes 1110 parts by weight. Each material is added in a manner that becomes the composition ratio described in Table 1. The flask was purged with nitrogen at 0.5MPa for 40 minutes, and then an azo polymerization initiator 2,2'-azobis(2,4-dimethylvaleronitrile) (ADVN) was added as a thermal initiator. Including the exothermic heat generated by the chemical reaction, the flask was kept at 65°C while stirring for 2 and a half hours. In order to react the residual monomers, ADVN was further added as a recovery agent and stirred at 80°C for 2 hours. After stirring, the flask was water-cooled and taken out when it reached below 40°C to obtain a polymer dilution.

[0142] To 100 parts by weight of the polymer diluent, 0.3 parts by weight of a photopolymerization initiator (Omnirad 819, manufactured by IGM Resins Co., Ltd.) and 3 parts by weight of trimethylolpropane triacrylate (TMPTA) were added based on solid content ratio to 100 parts by weight of the polymer to prepare an adhesive composition.

[0143] The adhesive composition was applied to a release liner to a thickness of 150 μm, and heated at 70°C for 5 minutes and then at 130°C for 2 minutes. Two identical adhesive layers were prepared and bonded together to obtain an adhesive sheet B having an adhesive layer with a thickness of 200 μm.

[0144] <Production Example 3: Preparation of Adhesive Sheet C Having First Adhesive Layer>

[0145] A pressure-sensitive adhesive sheet C was obtained in the same manner as in Production Example 2 except that the composition ratio of the materials used in the synthesis of the base polymer was changed to the composition ratio described in Table 1.

[0146] Table 1

[0147] Production Example 2 Production Example 3 2-Ethylhexyl acrylate (2EHA) 94％ 98％ 2-Hydroxyethyl Acrylate(HEA) 2％ 2％ Methacrylamide 4％ 2,2'-Azobis(2,4-dimethylvaleronitrile)(ADVN) 0.1％ 0.1％ Methyl Ethyl Ketone 61％ 61％ Ethyl acrylate 61％ 61％

[0148] <Example 1>

[0149] 1. Preparation of polarizer

[0150] As the thermoplastic resin substrate, a long amorphous polyethylene terephthalate copolymer film (thickness: 100 μm) having a Tg of about 75° C. was used. One surface of the resin substrate was subjected to a corona treatment.

[0151] 13 parts by weight of potassium iodide was added to 100 parts by weight of a PVA-based resin prepared by mixing polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMERZ410") in a ratio of 9:1 to prepare a PVA aqueous solution (coating solution).

[0152] The PVA aqueous solution was applied to the corona-treated surface of the resin substrate and dried at 60° C. to form a PVA-based resin layer having a thickness of 13 μm, thereby producing a laminate.

[0153] The obtained laminate was uniaxially stretched to 2.4 times at the free end in the longitudinal direction (length direction) between rolls having different peripheral speeds in an oven at 130° C. (in-air auxiliary stretching treatment).

[0154] Next, the laminate was immersed in an insolubilization bath (boric acid aqueous solution prepared by mixing 4 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 40° C. for 30 seconds (insolubilization treatment).

[0155] Next, the film was immersed in a dyeing bath (an iodine aqueous solution obtained by mixing iodine and potassium iodide at a weight ratio of 1:7 per 100 parts by weight of water) at a liquid temperature of 30° C. for 60 seconds (dyeing treatment) while adjusting the concentration so that the single body transmittance (Ts) of the polarizer finally obtained would be 43%.

[0156] Next, the sample was immersed in a crosslinking bath (boric acid aqueous solution prepared by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 40° C. for 30 seconds (crosslinking treatment).

[0157] Thereafter, the laminate was immersed in an aqueous boric acid solution (boric acid concentration: 4.0 wt %, potassium iodide: 5.0 wt %) at a liquid temperature of 70°C, and was uniaxially stretched (underwater stretching treatment) in the longitudinal direction (length direction) between rollers with different peripheral speeds so that the total stretching ratio became 5.5 times.

[0158] Thereafter, the laminate was immersed in a washing bath (an aqueous solution prepared by mixing 4 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 20° C. (washing treatment).

[0159] Thereafter, the laminate was dried in an oven maintained at 90° C. and brought into contact with a SUS heating roll maintained at a surface temperature of 75° C. for about 2 seconds (drying shrinkage treatment). The shrinkage rate in the width direction of the laminate due to the drying shrinkage treatment was 2%.

[0160] In this manner, a polarizer having a thickness of 5.0 μm was formed on the resin substrate.

[0161] 2. Preparation of polarizer

[0162] The HC-TAC film was bonded to the polarizer surface of the laminate of the resin substrate / polarizer obtained above via an ultraviolet curing adhesive. It should be noted that the HC-TAC film is a film having a hard coating (HC) layer (7 μm thick) formed on a triacetylcellulose (TAC) film (25 μm thick), and the film was bonded so that the TAC film became the polarizer side.

[0163] 3. Preparation of polarizing plate with second adhesive layer

[0164] Next, the resin substrate was peeled off, and the second adhesive layer (thickness 15 μm) was formed on the peeled surface using the adhesive composition A obtained in Manufacturing Example 1, to obtain a polarizing plate having a structure of an outer protective layer (HC-TAC film) / polarizer / second adhesive layer. The polarizing plate was punched into a size of 150 mm in length and 70 mm in width, and a through hole (diameter 3.8 mm) was formed at a position where the distance from the center of the through hole to the short side was 5 mm, so as to integrally penetrate from the outer protective layer to the second adhesive layer.

[0165] 4. Fabrication of optical laminates

[0166] A 150 μm thick adhesive sheet A was obtained, which was formed from an adhesive composition containing a base polymer obtained by polymerizing a monomer composition containing acrylamide and a photopolymerization initiator (product name: “Lucirin TPO”).

[0167] The polarizer obtained in 2. above is bonded to one surface of a glass plate (corresponding to the image display unit) via the second adhesive layer. Next, one release liner of the adhesive sheet obtained in Manufacturing Example 2 is peeled off, and a cover glass (manufactured by Nippon Electric Glass Co., Ltd., thickness 0.7 mm) is bonded thereto using a roll laminator. Next, the other release liner of the adhesive sheet is peeled off, and a vacuum laminator is used to adhere the surface of the outer protective layer of the polarizer, and the through-holes are filled with the adhesive sheet. The conditions for vacuum lamination are as follows: heating and pressing at 0.2 MPa and 60°C (standby time 90 seconds), followed by vacuum lamination at 100 Pa for 10 seconds. Next, a metal halide lamp (300 mW / cm 2 ) Accumulated light intensity 3000mJ / cm 2 ~3500mJ / cm 2 The adhesive sheet (first adhesive layer) was cured by ultraviolet light to produce an optical laminate. The obtained optical laminate was subjected to the evaluations of (4) to (6) above. The results are shown in Table 2.

[0168] <Examples 2 to 3 and Comparative Examples 1 to 3>

[0169] An optical layered body was produced in the same manner as in Example 1 except that the cover glass described in Table 1 was used as the cover glass. The obtained optical layered body was subjected to the same evaluation as in Example 1. Table 2 shows the results.

[0170] <Comparative Example 4>

[0171] An optical layered body was produced in the same manner as in Comparative Example 3 except that the adhesive sheet B was used instead of the adhesive sheet A. The obtained optical layered body was subjected to the same evaluation as in Example 1. Table 2 shows the results.

[0172] <Reference example>

[0173] An optical layered body was produced in the same manner as in Comparative Example 3 except that the adhesive sheet C was used instead of the adhesive sheet A. The obtained optical layered body was subjected to the same evaluation as in Example 1. Table 2 shows the results.

[0174] Table 2

[0175]

[0176] <Evaluation>

[0177] As shown in Table 2, when the embodiment of the present invention is used, excessive discoloration can be prevented in the periphery of the through hole. 2 ) Accumulated light intensity 3000mJ / cm 2 ~3500mJ / cm 2 The optical laminate was prepared in the same manner as in Comparative Examples 1 to 3 except for the ultraviolet rays. The prepared optical laminate was subjected to excessive discoloration evaluation, and as a result, excessive discoloration did not occur. On the other hand, since the first adhesive layer was not cured, the cover glass and the polarizing plate could not be sufficiently adhered to each other compared with the optical laminate obtained in the Examples and Comparative Examples, and it was difficult to maintain the laminated state, and it was difficult to actually use it for purposes such as image display devices.

[0178] Industrial Applicability

[0179] The image display device of the present invention can be suitably used as an image display device having a through hole (for example, a through hole corresponding to a camera portion) such as a smartphone, a tablet PC, or a smart watch.

Claims

1. An optical laminate, comprising: a cover glass having a transmittance of 7% to 50% at a wavelength of 243 nm; a first adhesive layer composed of a first adhesive composition which is an ultraviolet curable adhesive; A polarizing plate comprising a polarizer and a protective layer laminated on at least one surface of the polarizer; and A second adhesive layer composed of a second adhesive composition.

2. The optical layered body according to claim 1, wherein: The polarizer has a through hole, and the through hole is filled with the first adhesive composition.

3. The optical layered body according to claim 1, wherein: The protective layer is laminated only on the cover glass side surface of the polarizer.

4. The optical laminate according to claim 1, wherein: The first adhesive composition includes a base polymer having an amide skeleton and an acylphosphine oxide-based photopolymerization initiator.

5. The optical layered body according to claim 1, wherein: The cover glass comprises a metal oxide of an alkaline earth metal.

6. The optical layered body according to claim 5, wherein: The content of the metal oxide of the alkaline earth metal in the cover glass is 2 wt % to 12 wt %.

7. The optical layered body according to claim 1, wherein: The polarizer has a thickness of 15 μm or less. 8 . An image display device comprising the optical layered body according to claim 1 . 9 . An image display device comprising the optical layered body according to claim 2 , further comprising a camera unit at a position corresponding to the through hole.

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