Optical film stack and optical laminate

Abstract

This optical film stack includes: a first optical film having a first adhesive layer and disposed on the viewing side of the optical element through the first adhesive layer; and a second optical film having a second adhesive layer and disposed on the back side of the optical element through the second adhesive layer. A first glass film with a thickness of 50 μm or more and 150 μm or less is provided on the surface of the viewing side of the first optical film, and the thickness of the second adhesive layer is 50 μm or more and 200 μm or less.

Description

Technical Field

[0001] The present invention relates to an optical film stack and an optical laminate. Background Art

[0002] In recent years, liquid crystal cells equipped with a touch sensor function on the screen have been widely used in various fields from mobile phones to information displays.

[0003] As an example, a display panel can be cited in which a film or glass having a sensor function is laminated on a polarizing plate, and tempered glass called a "front plate" is disposed on the outermost layer through an adhesive layer for filling the step difference (step) on the sensor surface. In addition, recently, a liquid crystal panel called an "in-cell unit" has emerged in which a touch sensor is buried in a glass substrate of a liquid crystal cell from the viewpoints of thinning and weight reduction.

[0004] On the other hand, the thinning of tempered glass is also in progress. However, if the tempered glass is 300 μm or less, self-damage occurs due to the compressive stress of the glass, so the thinning is limited. In this case, although the use of resin has been studied to increase the hardness of the front plate, sufficient hardness cannot actually be obtained.

[0005] Therefore, a thin glass film has attracted attention as a front plate of a liquid crystal cell. This glass film is integrated with a polarizing plate through an adhesive layer, for example.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: International Publication No. 2013 / 175767 Summary of the Invention

[0009] Problems to be Solved by the Invention

[0010] However, in the case of a glass film disposed on the viewing side surface of an optical element such as a liquid crystal cell, the thickness is about 50 μm to 150 μm, which is very thin, so there is a problem that it is easily damaged when impacted.

[0011] The present invention has been made in view of the above problems, and an object thereof is to provide an optical film stack that can improve the breakage resistance of a glass film disposed on the viewing side of an optical element.

[0012] Means for Solving the Problems

[0013] This optical film stack includes: a first optical film having a first adhesive layer and disposed on the viewing side of the optical element through the first adhesive layer; and a second optical film having a second adhesive layer and disposed on the back side of the optical element through the second adhesive layer. A first glass film with a thickness of 50 μm or more and 150 μm or less is provided on the surface of the viewing side of the first optical film, and the thickness of the second adhesive layer is 50 μm or more and 200 μm or less.

[0014] Effects of the Invention

[0015] According to the disclosed technology, an optical film stack capable of improving the breakage resistance of the glass film disposed on the viewing side of the optical element can be provided. Description of the Drawings

[0016] Figure 1 It is an exemplary cross-sectional view of the optical film stack of the first embodiment.

[0017] Figure 2 It is an exemplary cross-sectional view of the optical film stack of the second embodiment.

[0018] Figure 3 It is an exemplary cross-sectional view of the optical laminate of the third embodiment.

[0019] Figure 4 It is an exemplary cross-sectional view of the optical laminate of the fourth embodiment.

[0020] Figure 5 It is an explanatory diagram of the ball drop test.

[0021] Figure 6 It is an explanatory diagram of the example.

[0022] Figure 7 It is an explanatory diagram of the comparative example.

[0023] Symbol Explanation

[0024] 1, 2 Optical film stack

[0025] 3, 4 Optical laminate

[0026] 10 First optical film

[0027] 11 First glass film

[0028] 12 First adhesive layer

[0029] 13 First polarizing plate

[0030] 14 First retardation layer

[0031] 18 First adhesive layer

[0032] 19. The first release film

[0033] 20, 20A. The second optical film

[0034] 21. The second glass film

[0035] 22. The second adhesive layer

[0036] 23. The second polarizer

[0037] 24. The second retardation layer

[0038] 25. The optical layer

[0039] 28. The second adhesive layer

[0040] 29. The second release film

[0041] 30. The liquid crystal cell

[0042] 131. The first polarizer

[0043] 132. The first protective film

[0044] 231. The second polarizer

[0045] 232. The second protective film Detailed implementation manners

[0046] Hereinafter, the embodiments (modes) for implementing the invention will be described with reference to the drawings. In each figure, the same reference numerals are given to the same components, and repeated descriptions are omitted.

[0047] 〈The first embodiment〉

[0048] Figure 1 It is an exemplary cross-sectional view of the optical film stack of the first embodiment. Refer to Figure 1 , the optical film stack 1 includes the first optical film 10 and the second optical film 20.

[0049] The first optical film 10 sequentially includes the first glass film 11, the first adhesive layer 12, the first polarizer 13, the first retardation layer 14, the first adhesive layer 18, and the first release film 19. It should be noted that the first retardation layer 14 is not necessarily configured and can be provided as needed.

[0050] It should also be noted that in this specification, the adhesive layer refers to a layer that has adhesiveness at room temperature and can be adhered to the adherend with a relatively light pressure. Therefore, even when the adherend adhered to the adhesive layer is peeled off, the adhesive layer can still maintain a practical adhesive force. On the other hand, the binder layer refers to a layer that can bond substances by existing between substances. Therefore, when the adherend adhered to the binder layer is peeled off, the binder layer does not have a practical adhesive force.

[0051] The first polarizing plate 13 has a first polarizing film 131 and a first protective film 132. The first protective film 132 is disposed on at least one side of the first polarizing film 131. The first protective film 132 is preferably disposed on at least the side of the first binder layer 12 of the first polarizing film 131, but may be disposed on both sides of the first polarizing film as needed.

[0052] The first retardation layer 14 is disposed on the side of the first polarizing plate 13 opposite to the first binder layer 12. The first retardation layer 14 can be laminated on the first polarizing plate 13 by an appropriate arbitrary adhesive layer or binder layer (not shown).

[0053] The first release film 19 is disposed on the side of the first retardation layer 14 opposite to the first polarizing plate 13 through the first adhesive layer 18.

[0054] The second optical film 20 sequentially includes a second release film 29, a second adhesive layer 28, a second retardation layer 24, a second polarizing plate 23, and an optical layer 25. It should be noted that the second retardation layer 24 and the optical layer 25 are not necessarily formed and can be provided as needed.

[0055] The second polarizing plate 23 has a second polarizing film 231. The second polarizing plate 23 may include a second protective film 232 disposed on one or both sides of the second polarizing film 231 as needed.

[0056] The second retardation layer 24 can be laminated on the second polarizing plate 23 by an appropriate arbitrary adhesive layer or binder layer (not shown).

[0057] The optical layer 25 can be disposed on both sides of the second polarizing plate 23 as needed. When the second polarizing plate 23 has the second protective film 232, the optical layer 25 is preferably disposed on the side of the second protective film 232 opposite to the second polarizing film 231. The optical layer 25 can be laminated on the second polarizing plate 23 by an appropriate arbitrary adhesive layer or binder layer (not shown).

[0058] Hereinafter, each component of the optical film group 1 will be described in more detail.

[0059] (First Optical Film)

[0060] Figure 1 Glass film

[0061] Regarding the first glass film 11, there is no particular limitation on it, and a suitable glass film can be adopted according to the purpose of use. When the first glass film 11 is classified according to its composition (components), for example, soda-lime glass, boric acid glass, aluminosilicate glass, quartz glass, etc. can be listed. In addition, when classified according to the alkali component, non-alkali glass and low-alkali glass can be listed. The content of the alkali metal component (e.g., Na 2 O, K 2 O, Li 2 O) of the glass is preferably 15% by weight or less, more preferably 10% by weight or less.

[0062] The thickness of the first glass film 11 is preferably 50 μm to 150 μm, more preferably 60 μm to 140 μm, still more preferably 70 μm to 130 μm, and particularly preferably 80 μm to 120 μm. Within such a range, processing with relatively high flexibility based on the roll-to-roll process can be carried out, and the first optical film 10 with excellent glass film breakage resistance and productivity can be obtained.

[0063] The light transmittance of the first glass film 11 at a wavelength of 550 nm is preferably 85% or more. The refractive index of the first glass film 11 at a wavelength of 550 nm is preferably 1.4 to 1.65.

[0064] The density of the first glass film 11 is preferably 2.3 g / cm 3 to 3.0 g / cm 3 , more preferably 2.3 g / cm 3 to 2.7 g / cm 3 . As long as the glass film is within this range, it can provide an optical film group 1 that contributes to the weight reduction of image display.

[0065] Regarding the forming method of the first glass film 11, there is no particular limitation on it, and a suitable glass film can be adopted according to the purpose of use. Generally, the first glass film 11 can be produced by the following method, that is, melting a mixture containing main raw materials such as silica and alumina, defoaming agents such as sodium sulfate and antimony oxide, and reducing agents such as carbon at a temperature of about 1400 °C to 1600 °C, forming it into a thin plate shape, and then cooling it, whereby the first glass film 11 can be produced. As the forming method of the first glass film 11, for example, the slot-draw method, the melting method, the floating method, etc. can be listed. For the glass film formed into a plate shape by these methods, in order to thin it or improve the smoothness, if necessary, it can also be chemically polished with a solvent such as hydrofluoric acid.

[0066] Figure 1 Adhesive layer ​​

[0067] Regarding the first adhesive layer 12, there are no particular limitations, and a suitable adhesive can be adopted according to the purpose of use. As the adhesive, for example, polyester adhesives, polyurethane adhesives, polyvinyl alcohol adhesives, and epoxy adhesives can be cited. Among them, epoxy adhesives that can obtain particularly good adhesion (close adhesion) are preferred.

[0068] When the first adhesive layer 12 is a thermosetting adhesive, heat resistance to peeling can be exhibited by heat curing (hardening). In addition, when the first adhesive layer 12 is a photo-curing adhesive such as an ultraviolet-curing adhesive, heat resistance to peeling can be exhibited by irradiating light such as ultraviolet light for hardening. Further, when the first adhesive layer 12 is a moisture-curing adhesive, since it can react with moisture in the air and so on to cause hardening, hardening can also be carried out by leaving it standing, and thus heat resistance to peeling can be exhibited.

[0069] The first adhesive layer 12 can use, for example, commercially available adhesives, or various curable resins can be dissolved or dispersed in a solvent to prepare an adhesive solution (or dispersion).

[0070] The thickness of the first adhesive layer 12 is preferably 10 μm or less, more preferably 0.1 μm to 10 μm, still more preferably 0.5 μm to 8 μm, and particularly preferably 1 μm to 6 μm. Within such a range, the first optical film 10 with better flexibility and excellent puncture resistance can be obtained.

[0071] The elastic modulus of the first adhesive layer 12 is preferably 0.5 GPa to 15 GPa, more preferably 0.8 GPa to 10 GPa, still more preferably 1 GPa to 5 GPa. Within such a range, the first optical film 10 with excellent flexibility and better puncture resistance can be obtained. In this specification, the elastic modulus can be measured by a precision universal testing machine (Autograph) under the following conditions.

[0072] [Elastic Modulus Measurement Method]

[0073] Measurement temperature: 23 °C

[0074] Sample size: 2 cm in width and 15 cm in length

[0075] Distance between chucks: 10 cm

[0076] Tensile speed: 10 mm / min.

[0077] [The First Polarizing Plate]

[0078] The thickness of the first polarizing plate 13 is preferably 5 μm to 300 μm, more preferably 10 μm to 250 μm, still more preferably 25 μm to 200 μm, and particularly preferably 25 μm to 100 μm.

[0079] The elastic modulus of the first polarizing plate 13 is preferably 1 GPa or more, more preferably 1 GPa to 10 GPa, still more preferably 2 GPa to 7 GPa, and particularly preferably 2 GPa to 5 GPa. Within such a range, the first optical film 10 with excellent puncture resistance can be obtained.

[0080] Regarding the shape of the first polarizing plate 13, there is no particular limitation thereto, and a suitable shape can be adopted according to the use purpose. As an example, a rectangular shape having a long side and a short side can be cited. In the case where the first polarizing plate 13 is in a rectangular shape, preferably, the absorption axis direction of the first polarizing film 131 included in the first polarizing plate 13 is substantially parallel to the long side or the short side of the first polarizing plate 13. It should be noted that in this specification, the concept of "substantially parallel" means that not only the case of strict parallelism is included, but also the case where the included angle between two lines is ±10° (preferably ±5°).

[0081] [First polarizing film]

[0082] Regarding the thickness of the first polarizing film 131, there is no particular limitation thereto, and a suitable thickness can be adopted according to the use purpose. The thickness of the first polarizing film 131 is generally about 1 μm to 80 μm. As the first polarizing film 131, a thinner polarizing film can be used. In this case, the thickness of the first polarizing film 131 is preferably 20 μm or less, more preferably 15 μm or less, still more preferably 10 μm or less, and particularly preferably 6 μm or less.

[0083] The first polarizing film 131 preferably exhibits absorption dichroism at any wavelength within the wavelength range of 380 nm to 780 nm. The monomer transmittance of the polarizing film is preferably 40.0% or more, more preferably 41.0% or more, still more preferably 42.0% or more, and particularly preferably 43.0% or more. The degree of polarization of the first polarizing film 131 is preferably 99.8% or more, more preferably 99.9% or more, still more preferably 99.95% or more.

[0084] The first polarizing film 131 is preferably an iodine-based polarizing film. Specifically, the polarizing film may be composed of a polyvinyl alcohol-based resin (hereinafter referred to as "PVA-based resin") film containing iodine.

[0085] As the PVA-based resin for forming the PVA-based resin film, there is no particular limitation thereto, and an appropriate resin can be adopted according to the use purpose. For example, polyvinyl alcohol and ethylene-vinyl alcohol copolymer can be cited.

[0086] Polyvinyl alcohol can be obtained by saponifying polyvinyl acetate. Ethylene-vinyl alcohol copolymer can be obtained by saponifying ethylene-vinyl acetate copolymer. The saponification degree of PVA-based resins is usually 85 mol% to 100 mol%, preferably 95.0 mol% to 99.95 mol%, more preferably 99.0 mol% to 99.93 mol%. The saponification degree can be determined based on JIS K 6726-1994. By using PVA-based resins with such a saponification degree, a polarizing plate with better durability can be obtained. However, if the saponification degree is too high, gelation may also occur.

[0087] Regarding the average degree of polymerization of PVA-based resins, there is no particular limitation, and it can be appropriately selected according to the intended use. The average degree of polymerization of PVA-based resins is, for example, 1000 to 10,000, preferably 1200 to 5000, more preferably 1500 to 4500. It should be noted that the average degree of polymerization can be determined based on JIS K6726-1994.

[0088] As a method for manufacturing the first polarizing plate 131, for example, a method (I) of stretching and dyeing a PVA-based resin film monomer, a method (II) of stretching and dyeing a laminate (i) having a resin substrate and a polyvinyl alcohol-based resin layer, etc. can be cited. Method (I) is a well-known conventional method in the industry, so its detailed description is omitted.

[0089] Method (II) preferably includes a step of stretching and dyeing a laminate (i) having a resin substrate and a polyvinyl alcohol-based resin layer formed on one side of the resin substrate, thereby manufacturing a polarizing plate on the resin substrate. The laminate (i) can be formed by coating a coating liquid containing a polyvinyl alcohol-based resin on the resin substrate and drying it. In addition, the laminate (i) can also be formed by transcribing (transferring) the polyvinyl alcohol-based resin layer onto the resin substrate. The detailed content of this manufacturing method (II) is described, for example, in Japanese Patent Laid-Open No. 2012-73580, which is incorporated herein by reference.

[0090] [First protective film]

[0091] As the first protective film 132, there is no particular limitation, and a suitable resin film can be adopted according to the usage purpose. As the material for forming the first protective film 132, for example, polyester resins such as polyethylene terephthalate (PET), cellulose resins such as triacetyl cellulose (TAC), cycloolefin resins such as norbornene resins, olefin resins such as polyethylene and polypropylene, (meth)acrylic resins, etc. can be cited. Among these, polyethylene terephthalate (PET) is preferred. It should be noted that the “(meth)acrylic resin” refers to acrylic resin and / or methacrylic resin.

[0092] As the (meth)acrylic resin, for example, a (meth)acrylic resin having a glutarimide structure can be used. The (meth)acrylic resin having a glutarimide structure (hereinafter also referred to as glutarimide resin) is described, for example, in Japanese Patent Application Laid-Open No. 2006-309033, Japanese Patent Application Laid-Open No. 2006-317560, Japanese Patent Application Laid-Open No. 2006-328329, Japanese Patent Application Laid-Open No. 2006-328334, Japanese Patent Application Laid-Open No. 2006-337491, Japanese Patent Application Laid-Open No. 2006-337492, Japanese Patent Application Laid-Open No. 2006-337493, Japanese Patent Application Laid-Open No. 2006-337569, Japanese Patent Application Laid-Open No. 2007-009182, Japanese Patent Application Laid-Open No. 2009-161744, and Japanese Patent Application Laid-Open No. 2010-284840. The contents of these descriptions are incorporated herein by reference.

[0093] The first protective film 132 and the first polarizing plate 131 can be laminated by an appropriate optional adhesive layer. Regarding the resin substrate used in the production of the first polarizing plate 131, it can be peeled off before or after the lamination of the first protective film 132 and the first polarizing plate 131.

[0094] The thickness of the first protective film 132 is preferably 4 μm to 250 μm, more preferably 5 μm to 150 μm, still more preferably 10 μm to 100 μm, and particularly preferably 10 μm to 50 μm.

[0095] The elastic modulus of the first protective film 132 is 1 GPa or more, preferably 1 GPa to 10 GPa, more preferably 1.8 GPa to 7 GPa, and still more preferably 2 GPa to 5 GPa. Within such a range, the first optical film 10 with excellent puncture resistance can be obtained.

[0096] [First retardation layer]

[0097] Regarding the first retardation layer 14, there is no particular limitation, and it may have appropriate arbitrary optical properties and / or mechanical properties according to the purpose of use. The first retardation layer 14 usually has a slow axis. The optical properties and / or mechanical properties of the first retardation layer 14 can be appropriately selected according to the alignment mode of the liquid crystal cell.

[0098] The first retardation layer 14 may have an inverse dispersion wavelength characteristic in which the retardation value increases with the wavelength of the measurement light, a positive wavelength dispersion characteristic in which the retardation value decreases with the wavelength of the measurement light, or a relatively flat wavelength dispersion characteristic in which the retardation value basically does not change with the wavelength of the measurement light.

[0099] The thickness of the first retardation layer 14 is preferably 60 μm or less, more preferably 30 μm to 55 μm, and even more preferably 30 μm or less.

[0100] The first retardation layer 14 may be composed of an appropriate arbitrary resin film that can satisfy the above characteristics. As typical examples of such resins, cycloolefin resins, polycarbonate resins, cellulose resins, polyester resins, polyvinyl alcohol resins, polyamide resins, polyimide resins, polyether resins, polystyrene resins, acrylic resins, and liquid crystal polymers can be cited.

[0101] [First Adhesive Layer]

[0102] The first adhesive layer 18 can be formed by an appropriate arbitrary adhesive. As the adhesive, for example, an adhesive based on a polymer such as an acrylic polymer, a silicone resin polymer, a polyester, a polyurethane, a polyamide, a polyether, or a fluororubber can be used. An acrylic adhesive is preferably used. The reason is that the acrylic adhesive has excellent optical transparency, shows adhesive characteristics of moderate wettability, cohesion, and adhesiveness, and has excellent weather resistance, heat resistance, etc. In particular, an acrylic adhesive made of an acrylic polymer having 4 to 12 carbon atoms is even better.

[0103] The first adhesive layer 18 is formed of the adhesive. There is no particular limitation on the thickness of the first adhesive layer 18, for example, it is about 1 to 400 μm. In addition, regarding the thickness of the first adhesive layer 18, the appropriate preferred range of this thickness can be set by the manufacturing method of the (meth)acrylic polymer used in the adhesive. For example, in the case of manufacturing the (meth)acrylic polymer by solution polymerization or the like, the thickness of the first adhesive layer 18 is preferably 1 to 100 μm, more preferably 2 to 50 μm, still more preferably 2 to 40 μm, and particularly preferably 5 to 35 μm. In addition, in the case of manufacturing the (meth)acrylic polymer by radiation polymerization or the like, the thickness of the first adhesive layer 18 is preferably 50 to 400 μm, more preferably 75 to 300 μm, still more preferably 100 to 200 μm.

[0104] When manufacturing an acrylic polymer with such a thickness, solution polymerization is preferred.

[0105] [First release film]

[0106] The first release film 19 can be formed of a resin such as polyethylene terephthalate (PET), for example. The thickness of the first release film 19 is preferably 5 μm to 200 μm, more preferably 10 μm to 100 μm, still more preferably 30 μm to 50 μm. Regarding the first release film 19, it is peeled off from the interface with the first adhesive layer 18 before attaching the first optical film 10 to an optical element such as a liquid crystal cell.

[0107] (Second optical film)

[0108] The dimensional change of the second optical film 20 is preferably 0.5% or less, more preferably 0% to 0.2%. The optical film set 1 combines the first optical film 10 having the first glass film 11 and the second optical film 20 having the dimensional change as described above. Therefore, by disposing the first optical film 10 and the second optical film 20 on both sides of the liquid crystal cell respectively, an optical laminate (first optical film / liquid crystal cell / second optical film) with less warpage can be obtained.

[0109] It should be noted that the dimensional change means the dimensional change rate when a rectangular sample having a length X (for example, 20 cm) along the absorption axis direction of the second polarizer 231 is allowed to stand in an environment at a temperature of 80°C for 150 hours, that is, (|the length X of the absorption axis direction before the test - the length X1 of the absorption axis direction after the test| / the length X of the absorption axis direction before the test) × 100. The dimensional change can be measured by a planar biaxial measuring machine, for example, Quick Vision (manufactured by Mitutoyo Corporation). 0 of the absorption axis direction of the absorption axis direction before the test 0 - the length X1 of the absorption axis direction after the test | / the length X of the absorption axis direction before the test 0 ).

[0110] [Second release film]

[0111] The second release film 29 can be formed of a resin such as polyethylene terephthalate (PET), for example. The thickness of the second release film 29 is preferably 5 μm to 200 μm, more preferably 10 μm to 100 μm, and even more preferably 30 μm to 50 μm. With respect to the second release film 29, it can be peeled off from the interface with the second adhesive layer 28 before the second optical film 20 is attached to an optical element such as a liquid crystal cell.

[0112] [Second Adhesive Layer]

[0113] The second adhesive layer 28 can be formed of an appropriate arbitrary adhesive. As the adhesive, other than the thickness of the first adhesive layer 18, the others can be the same.

[0114] The thickness of the second adhesive layer 28 is 50 μm or more and 200 μm or less. If the thickness of the second adhesive layer 28 is 50 μm or more and 200 μm or less, then when the optical laminate 3 described later is formed, the damage resistance of the first glass film 11 can be improved. Especially when the thickness of the first glass film 11 is 50 μm or more and 150 μm or less, the first glass film 11 is thin and easily damaged. Therefore, it is very meaningful to make the thickness of the second adhesive layer 28 50 μm or more and 200 μm or less to improve the damage resistance of the first glass film 11.

[0115] When manufacturing an acrylic polymer with such a thickness, radiation polymerization is preferred.

[0116] [Second Polarizer]

[0117] The thickness of the second polarizer 23 is preferably 5 μm to 250 μm, more preferably 10 μm to 200 μm, even more preferably 25 μm to 200 μm, and particularly preferably 25 μm to 100 μm.

[0118] Regarding the shape of the second polarizer 23, there is no particular limitation, and a suitable shape is adopted according to the use purpose. As an example, a rectangular shape having a long side and a short side can be cited. When the second polarizer 23 is in a rectangular shape, preferably, the absorption axis direction of the second polarizing film 231 included in the second polarizer 23 is substantially parallel to the long side or the short side of the second polarizer 23.

[0119] Regarding the relationship between the second polarizer 23 and the first polarizer 13, as an example, the absorption axis direction of the first polarizing film 131 is substantially parallel to the short side of the first polarizer 13, and the absorption axis of the second polarizing film 231 is substantially parallel to the long side of the second polarizer 23.

[0120] Regarding the relationship between the second polarizing plate 23 and the first polarizing plate 13, as another example, the absorption axis direction of the first polarizing film 131 is substantially parallel to the long side of the first polarizing plate 13, and the absorption axis of the second polarizing film 231 is substantially parallel to the short side of the second polarizing plate 23.

[0121] [Second polarizing film]

[0122] The thickness of the second polarizing film 231 is 1 μm to 10 μm, preferably 2 μm to 7 μm. Within such a range, the second optical film 20 with less dimensional change can be obtained. By disposing the first optical film 10 and the second optical film 20 on both sides of the liquid crystal cell respectively, an optical laminate (first optical film / liquid crystal cell / second optical film) with less warping can be obtained.

[0123] Regarding the monomer transmittance, material, manufacturing method, etc. of the second polarizing film 231, the same description as that of the aforementioned first polarizing film 131 can be exemplified.

[0124] [Second protective film]

[0125] As the second protective film 232, for example, the same protective film as the aforementioned first protective film 132 can be used.

[0126] [Second retardation layer]

[0127] As the second retardation layer 24, for example, the same retardation layer as the aforementioned first retardation layer 14 can be used.

[0128] [Optical layer]

[0129] As the optical layer 25, for example, an antireflection layer, an antiglare layer, etc. can be cited. The thickness of the optical layer is, for example, 1 μm to 200 μm.

[0130] In the optical film group 1, since the first optical film 10 is a polarizing plate integrated with a thin glass having the first glass film 11, it has a high hardness. In addition, the first optical film 10 has the first polarizing plate 13 on one side of the first glass film 11, whereby the breakage of the first glass film 11 can be prevented and the puncture resistance is also excellent. Since the point compressive energy applied to the surfaces of the first optical film 10 and the first glass film 11 can be effectively escaped to the first polarizing plate 13 side, as described above, the puncture resistance is excellent.

[0131] Although the first optical film 10 can function as described above, when forming a liquid crystal panel, when the first optical film 10 is used as the viewing side polarizing plate and the previous polarizing plate is used for the back side, the laminate composed of the liquid crystal cell and the polarizing plate (first optical film 10 / liquid crystal cell / previous polarizing plate) also tends to warp easily.

[0132] On the other hand, by using the optical film group 1 including the first optical film 10 and the second optical film 20, and disposing the first optical film 10 and the second optical film 20 on both sides of the liquid crystal cell respectively, an optical laminate (the first optical film 10 / liquid crystal cell / second optical film 20) with less warpage can be obtained.

[0133] This is the effect obtained by using the second optical film 20 as an optical film combined with the first optical film 10 having less dimensional change caused by damp heat, and making the difference in dimensional change between the first optical film 10 and the second optical film 20 small by providing the first glass film 11.

[0134] It should be noted that, as described later, the first optical film 10 can be disposed and used on the viewing side of the liquid crystal cell, and functions as the front plate of the liquid crystal panel. On the other hand, the second optical film 20 can be disposed and used on the back side of the liquid crystal cell. It should be noted that the viewing side (observation side) means the side facing the person who views (observes) when a predetermined component is applied to the image display device. In addition, the back side means the opposite side of the viewing side.

[0135] The optical film group 1 is preferably applied to, for example, an in-cell liquid crystal element. The in-cell liquid crystal element is a liquid crystal element including a liquid crystal cell, and this liquid crystal element has a substrate in which a touch sensor is embedded. The first optical film 10 is disposed, for example, on the viewing side of the liquid crystal cell, and the second optical film 20 is disposed, for example, on the back side of the liquid crystal cell. In addition, the optical film group 1 is preferably applied to an image display device that requires chemical resistance. In this case, in the optical film group 1, the first optical film 10 is used, for example, with the first glass film 11 on the outside.

[0136] <Second Embodiment>

[0137] In the second embodiment, an example of an optical film group having a layer structure different from that of the first embodiment is shown. It should be noted that in the second embodiment, there are cases where the description of the same constituent parts as those in the already described embodiments is omitted.

[0138] Figure 2 is an exemplary cross-sectional view of the optical film group of the second embodiment. Refer to Figure 2 , the optical film group 2 includes the first optical film 10 and the second optical film 20A. That is, the optical film group 2 is different from the optical film group 1 (refer to Figure 1 ) in that the second optical film 20 is replaced with the second optical film 20A.

[0139] The second optical film 20A sequentially includes a second release film 29, a second adhesive layer 28, a second retardation layer 24, a second polarizing plate 23, a second adhesive layer 22, a second glass film 21, and an optical layer 25. It should be noted that the second retardation layer 24 and the optical layer 25 are not necessarily formed and can be provided as needed.

[0140] The elastic modulus of the second adhesive layer 22 is preferably 1 GPa or more, more preferably 1 GPa to 10 GPa, still more preferably 2 GPa to 8 GPa, and particularly preferably 2 GPa to 5 GPa. Within such a range, not only can the flexibility be maintained, but also the dimensional change can be suppressed.

[0141] Regarding the material, thickness, etc. of the second adhesive layer 22, the same description as that of the aforementioned first adhesive layer 12 can be exemplified.

[0142] The thickness of the second glass film 21 is preferably 20 μm to 150 μm, more preferably 40 μm to 130 μm, still more preferably 60 μm to 110 μm. Within such a range, a second optical film 20A with relatively excellent flexibility can be obtained.

[0143] The second glass film 21 is, for example, thinner than the first glass film 11. The reason is that for the first glass film 11, since it will be in direct contact with the outside, a certain degree of strength is required. However, for the second glass film 21, as long as it can suppress the dimensional change of the resin and can be processed by a roll-to-roll process.

[0144] Regarding the material, transmittance, refractive index, density, forming method, etc. of the second glass film 21, the same description as that of the aforementioned first glass film 11 can be exemplified.

[0145] Thus, in the optical film group 2, the second optical film 20A further includes a second adhesive layer 22 and a second glass film 21 in addition to the configuration of the second optical film 20. By using the optical film group 2 including the first optical film 10 and the second optical film 20A and disposing the first optical film 10 and the second optical film 20A on both sides of the liquid crystal cell, an optical laminate (first optical film 10 / liquid crystal cell / second optical film 20A) with less warpage can be obtained.

[0146] In addition, the optical film group 2 is preferably applied to a liquid crystal cell, an image display device requiring chemical resistance, etc. in the same manner as the optical film group 1.

[0147] <Third Embodiment>

[0148] In the third embodiment, an example of an optical laminate having the optical film group of the first embodiment is shown. It should be noted that in the third embodiment, there are cases where the description of the same components as those in the already described embodiments is omitted.

[0149] Figure 3 is an exemplary cross-sectional view of the optical laminate of the third embodiment. Refer to Figure 3 , the optical laminate 3 includes, in order from the viewing side, a first optical film 10 after peeling off the first release film 19, a liquid crystal cell 30, and a second optical film 20 after peeling off the second release film 29.

[0150] That is, in the optical laminate 3, the first optical film 10 is laminated on the viewing side of the liquid crystal cell 30, and the second optical film 20 is laminated on the side of the liquid crystal cell 30 opposite to the viewing side (back side).

[0151] The first optical film 10 can be configured, for example, to be composed of a first glass film 11, a first adhesive layer 12, a first polarizing plate 13, a first retardation layer 14, and a first adhesive layer 18 in order from the viewing side. In addition, the second optical film 20 can be configured, for example, to be composed of a second adhesive layer 28, a second retardation layer 24, a second polarizing plate 23, and an optical layer 25 in order from the viewing side. It should be noted that, as described above, the first retardation layer 14, the second retardation layer 24, and the optical layer 25 can be provided as needed.

[0152] In this way, by disposing the first optical film 10 and the second optical film 20 on both sides of the liquid crystal cell 30 respectively, the optical laminate 3 can be obtained.

[0153] As described above, the thickness of the second adhesive layer 28 is 50 μm or more and 200 μm or less. Accordingly, the damage resistance of the first glass film 11 in the optical laminate 3 can be improved. In particular, when the thickness of the first glass film 11 is 50 μm or more and 150 μm or less, the first glass film 11 is relatively thin and is likely to break. Therefore, it is very meaningful to make the thickness of the second adhesive layer 28 50 μm or more and 200 μm or less to improve the damage resistance of the first glass film 11.

[0154] It should be noted that the optical laminate 3 is preferably configured such that the absorption axes of the first polarizer 131 and the second polarizer 231 are substantially orthogonal (perpendicular). If it is such a configuration, an optical laminate 3 that is less likely to warp can be obtained. It should be noted that the concept of "substantially orthogonal" means not only the case of strict orthogonality, but also the case where the included angle between the two lines is 90° ± 10° (preferably 90° ± 5°).

[0155] <Fourth Embodiment>

[0156] In the fourth embodiment, an example of an optical laminate having the optical film group of the second embodiment is shown. It should be noted that in the fourth embodiment, there are cases where the description of the same components as those in the already described embodiments is omitted.

[0157] Figure 4 is an exemplary cross-sectional view of the optical laminate of the fourth embodiment. Refer to Figure 4 , the optical laminate 4 sequentially includes, from the viewing side, a first optical film 10 after peeling off the first release film 19, a liquid crystal cell 30, and a second optical film 20A after peeling off the second release film 29.

[0158] That is, the optical laminate 4 is different from the optical laminate 3 (refer to Figure 3 ) in that the second optical film 20 is replaced by the second optical film 20A.

[0159] The first optical film 10 can be configured, for example, to be composed of a first glass film 11, a first adhesive layer 12, a first polarizing plate 13, a first retardation layer 14, and a first adhesive layer 18 in this order from the viewing side. In addition, the second optical film 20A can be configured, for example, to be composed of a second adhesive layer 28, a second retardation layer 24, a second polarizing plate 23, a second adhesive layer 22, a second glass film 21, and an optical layer 25 in this order from the viewing side. It should be noted that, as described above, the first retardation layer 14, the second retardation layer 24, and the optical layer 25 can be provided as needed.

[0160] In this way, by disposing the first optical film 10 and the second optical film 20A on both sides of the liquid crystal cell 30 respectively, the optical laminate 4 can be obtained.

[0161] As described above, the thickness of the second adhesive layer 28 is 50 μm or more and 200 μm or less. Accordingly, the damage resistance of the first glass film 11 in the optical laminate 4 can be improved. In particular, when the thickness of the first glass film 11 is 50 μm or more and 150 μm or less, the first glass film 11 is relatively thin and easily broken. Therefore, it is very meaningful to make the thickness of the second adhesive layer 28 50 μm or more and 200 μm or less to improve the damage resistance of the first glass film 11.

[0162] It should be noted that the optical laminate 4 is preferably configured such that the absorption axes of the first polarizer 131 and the second polarizer 231 are substantially orthogonal (perpendicular). If configured in this way, an optical laminate 4 that is less likely to warp can be obtained.

[0163] [Examples]

[0164] Hereinafter, examples and comparative examples are listed to more specifically illustrate the optical film group and the optical laminate, but the present invention is not limited to these examples. In addition, in the examples, unless otherwise specified, "parts" and "%" are based on weight.

[0165] [Production Example 1] Preparation of Polarizing Plate A

[0166] For a polyvinyl alcohol film (PVA) with a thickness of 100 μm, it was dyed for 1 minute at 30 °C in an iodine solution with a concentration of 0.3% between rollers with different speed ratios while being stretched to 3 times. Then, it was immersed for 0.5 minute at 60 °C in an aqueous solution containing boric acid with a concentration of 4% and potassium iodide with a concentration of 10% while being stretched to a total elongation ratio of 6 times. Next, it was immersed in an aqueous solution containing potassium iodide with a concentration of 1.5% at 30 °C for 10 seconds for washing and then dried at 50 °C for 4 minutes, thereby obtaining a polarizing plate with a thickness of 28 μm. A triacetyl cellulose film (TAC) with a thickness of 40 μm and an elastic modulus of 3.6 GPa after saponification was adhered to one surface of the polarizing plate with a polyvinyl alcohol-based adhesive, and an acrylic resin film with a thickness of 30 μm and an elastic modulus of 2.5 GPa was adhered to the other surface with a polyvinyl alcohol-based adhesive, thereby obtaining polarizing plate A (thickness: 98 μm).

[0167] [Production Example 2] Preparation of Polarizing Plate B

[0168] (Preparation of Polarizing Film)

[0169] First, for a laminate in which a PVA layer with a thickness of 9 μm was formed on an amorphous PET substrate, it was subjected to air-assisted stretching with an elongation temperature of 130 °C, thereby generating a stretched laminate. Next, the stretched laminate was dyed to generate a colored laminate, and then the colored laminate was stretched in boric acid water with an elongation temperature of 65 °C, thereby generating an optical film laminate including a 4-μm-thick PVA layer that was stretched integrally with the amorphous PET substrate at a total elongation ratio of 5.94 times.

[0170] By such two-stage stretching, an optical film laminate including a 4-μm-thick PVA layer for constituting a high-functional polarizing film can be generated. For this high-functional polarizing film, the PVA molecules of the PVA layer formed on the amorphous PET substrate are highly (higher-order) oriented, and the iodine adsorbed by dyeing is highly oriented in one direction as a polyiodide ion complex.

[0171] (Preparation of Acrylic Film)

[0172] The methacrylic resin particles having glutarimide ring units were dried at 100.5 kPa and 100 °C for 12 hours, and then extruded from a T-die by a single-screw extruder at a die temperature of 270 °C to be formed into a film. For this film, it was stretched in the conveying direction (MD direction) in an atmosphere 10 °C higher than the Tg of the resin, and then, it was stretched in the direction orthogonal to the conveying direction of the film (TD direction) in an atmosphere 7 °C higher than the Tg of the resin, thereby obtaining an acrylic film with a thickness of 40 μm and an elastic modulus of 2.5 GPa.

[0173] (Preparation of curable adhesive)

[0174] 35 parts by weight of N-hydroxyethyl acrylamide (HEAA, manufactured by Kojin Co., Ltd.), 45 parts by weight of N-acryloylmorpholine (ACMO, manufactured by Kojin Co., Ltd.), 25 parts by weight of tripropylene glycol diacrylate (TPGDA, manufactured by Toagosei Co., Ltd., "trade name" ARONIX M-220), 3 parts by weight of a photoinitiator (manufactured by Ciba Japan K.K., trade name "IRGACURE184"), and 1.5 parts by weight of another photoinitiator (manufactured by Nippon Kayaku Co., Ltd., trade name "KAYACURE DETX-S") were mixed to obtain a curable adhesive.

[0175] (Manufacture of polarizing plate)

[0176] The curable adhesive was coated on the polarizing film formed on a PET film, and the coating thickness was about 1 μm. Next, the 40-μm acrylic film was adhered to the adhesive layer. Then, from the PET film side, ultraviolet rays with a peak UV illuminance of 1600 mW / cm 2 and a total UV light amount of 1000 mJ / cm 2 (wavelength 380 - 440 nm) were irradiated by a conveyor-type UV irradiation device (manufactured by Fusion Co., Ltd.) to cure the adhesive, and then dried at 70 °C for 2 minutes. Finally, the PET film was peeled off from the laminate of the acrylic film, the polarizing film, and the PET film, thereby obtaining a laminate of the acrylic film (protective film) and the polarizing film (polarizing plate B with a thickness of 44 μm).

[0177] [Production Example 3] Preparation of adhesive

[0178] (Preparation of acrylic polymer)

[0179] In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet tube, and a cooler, 100 parts by weight of butyl acrylate, 5 parts by weight of acrylic acid, 0.075 parts by weight of 2-hydroxyethyl acrylate, 0.2 parts by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator, and 200 parts by weight of ethyl acetate as a polymerization solvent were prepared. After sufficient nitrogen replacement, while stirring under a nitrogen gas stream, the liquid temperature in the flask was maintained at around 55°C and a polymerization reaction was carried out for 10 hours, thereby preparing an acrylic polymer solution. The weight average molecular weight of the acrylic polymer was 2.2 million.

[0180] (Preparation of Adhesive Composition)

[0181] 0.2 parts by weight of benzoyl peroxide (NYPER BMT, manufactured by NOF Corporation) as a peroxide, 0.05 parts by weight of diglycidylaminomethylcyclohexane (TETRAD C, manufactured by Mitsubishi Gas Chemical Company) as an epoxy crosslinking agent, 0.1 parts by weight of an adduct of trimethylolpropane / toluene diisocyanate (CORONATE L, manufactured by Nippon Polyurethane Industry Co., Ltd.) as an isocyanate crosslinking agent, and 0.075 parts by weight of a silane coupling agent (KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.) were uniformly mixed and stirred into 100 parts by weight of the acrylic polymer solution in terms of solid content, thereby preparing an acrylic adhesive (solid content: 10.9% by weight).

[0182] [Production Example 4] Preparation of Adhesive

[0183] (Preparation of Monomer Components for UV Polymerization)

[0184] 61 parts by weight of 2-ethylhexyl acrylate (2EHA), 14 parts by weight of N-vinyl-2-pyrrolidone (NVP), 0.05 parts by weight of two photoinitiators (trade name: IRGACURE184, manufactured by BASF), and 0.05 parts by weight of a photoinitiator (trade name: IRGACURE651, manufactured by BASF) were put into a four-necked flask, thereby preparing a monomer mixture. Next, the monomer mixture was exposed to ultraviolet light in a nitrogen atmosphere to carry out partial photopolymerization, thereby obtaining a partial polymer (acrylic polymer syrup) with a polymerization rate of approximately 10% by weight.

[0185] To 75.1 parts by weight of the total amount of the obtained acrylic polymer syrup, 3 parts by weight of 2-hydroxyethyl acrylate (2HEA), 22 parts by weight of butyl 4-hydroxyacrylate (HBA), and 0.06 parts by weight of dipentaerythritol pentaacrylate (trade name "KAYARAD DPHA", manufactured by Nippon Kayaku Co., Ltd.) were added, and they were uniformly mixed to prepare a monomer component.

[0186] [Production Example 5] Preparation of Adhesive

[0187] (Preparation of Epoxy Adhesive)

[0188] 70 parts by weight of CELLOXIDE 2021P (manufactured by Daicel Chemical Industries, Ltd.), 5 parts by weight of EHPE3150, 19 parts by weight of RONE OXETANEOXT-221 (manufactured by Toagosei Co., Ltd.), 4 parts by weight of KBM-403 (manufactured by Shin-Etsu Chemical Co., Ltd.), and 2 parts by weight of CPI101A (manufactured by SANAPRO Co., Ltd.) were mixed to prepare an epoxy adhesive.

[0189] [Example 1]

[0190] (Production of the First Optical Film A)

[0191] For a glass film (manufactured by Nippon Electric Glass Co., Ltd., trade name "OA-10G", thickness: 100 μm) and the polarizing plate A produced in Production Example 1, they were bonded using an adhesive layer composed of the adhesive prepared in Production Example 5. At this time, the polarizing plate A was arranged such that the acrylic film was on the glass film side. Then, ultraviolet rays (500 mJ / cm 2 ) were irradiated onto the adhesive layer using a high-pressure mercury lamp to harden the adhesive layer, thereby obtaining the first optical film A. The thickness of the adhesive layer was 5 μm, and the elastic modulus was 1.8 GPa.

[0192] (Preparation of the Second Optical Film A)

[0193] The polarizing plate B produced in Production Example 2 was prepared as the second optical film B.

[0194] (Production of the Evaluation Laminate A)

[0195] A glass plate (13.3 inches, 296 mm × 168 mm, thickness: 0.4 mm) similar to a glass cell was prepared.

[0196] The first optical film A was cut into a size of 295 mm × 163 mm such that the absorption axis direction of the polarizing sheet was parallel to the short side.

[0197] The second optical film B was cut into a size of 295 mm × 163 mm such that the absorption axis direction of the polarizing plate is parallel to the long side.

[0198] On one surface of the glass plate, the first optical film A was laminated in such a manner that the short sides of the glass plate and the first optical film A are parallel to each other and the polarizing plate A (polarizing film) is on the glass plate side.

[0199] On the other surface of the glass plate, the second optical film B was laminated in such a manner that the short sides of the glass plate and the second optical film A are parallel to each other and the polarizing film is on the glass plate side.

[0200] The first optical film A was laminated on the glass plate using an adhesive layer (thickness: 20 μm) composed of the adhesive prepared in Production Example 3. It should be noted that the adhesive layer was formed as follows. That is, (i) it was coated on a polyethylene terephthalate film (manufactured by Mitsubishi Chemical POLYESTER FILM Co., thickness: 38 μm) that had been subjected to a silicone resin treatment and heated at 155°C for 1 minute, thereby forming an adhesive layer with a dried thickness of 20 μm, and (ii) the adhesive layer was transferred (transcribed) from the polyethylene terephthalate film to the polarizing plate A, thereby forming the adhesive layer.

[0201] The second optical film B was laminated on the glass plate using an adhesive layer (thickness 50 μm) composed of the adhesive prepared in Production Example 4. It should be noted that for this adhesive layer, the monomer components adjusted in Production Example 4 were coated on the release-treated surface of a 38-μm-thick POLYESTER FILM (trade name: DIAFOIL MRF, manufactured by Mitsubishi Resin Co., Ltd.) that had been release-treated on one side with silicone resin in such a manner that the final thickness became 100 μm, thereby forming a coating layer. Next, on the surface coated with the monomer components, a 38-μm-thick POLYESTER FILM (trade name: DIAFOILMRE, manufactured by Mitsubishi Resin Co., Ltd.) that had been release-treated on one side with silicone resin was covered in such a manner that the release-treated surface of this film (POLYESTER FILM) was on the coating layer side. Thereby, the coating layer of the monomer components was blocked (isolated) from oxygen. On the sheet having the coating layer thus obtained, using CHEMIMCAL LIGHT (manufactured by Toshiba Corporation), irradiation was carried out for 360 seconds at an illuminance of 5 mW / cm 2Irradiation with ultraviolet rays (when measured by TOPCON UVR-T1 having the maximum sensitivity at approximately 350 nm) cures the coating layer to form an adhesive layer, and thus an adhesive sheet was produced. The polyester films (POLYESTER FILM) covering both surfaces of the adhesive layer function as release films.

[0202] Next, the polyester film (POLYESTER FILM) on one surface was peeled off and laminated on the optical film B, and then the polyester film on the other surface was also peeled off.

[0203] Through the above, the evaluation laminate A was produced.

[0204] [Example 2]

[0205] An evaluation laminate B was produced in the same manner as in Example 1, except that the thickness of the adhesive layer composed of the adhesive prepared in Production Example 4 was 150 μm.

[0206] [Example 3]

[0207] An evaluation laminate C was produced in the same manner as in Example 1, except that the thickness of the adhesive layer composed of the adhesive prepared in Production Example 4 was 200 μm.

[0208] [Example 4]

[0209] An evaluation laminate D was produced in the same manner as in Example 1, except that the thickness of the glass film was 50 μm.

[0210] [Example 5]

[0211] An evaluation laminate E was produced in the same manner as in Example 1, except that the thickness of the glass film was 50 μm and the thickness of the adhesive layer composed of the adhesive prepared in Production Example 4 was 150 μm.

[0212] [Example 6]

[0213] An evaluation laminate F was produced in the same manner as in Example 1, except that the thickness of the glass film was 50 μm and the thickness of the adhesive layer composed of the adhesive prepared in Production Example 4 was 200 μm.

[0214] [Comparative Example 1]

[0215] The second optical film B is laminated on the glass plate using (via) an adhesive layer (thickness: 20 μm) composed of the adhesive prepared in Production Example 3. It should be noted that the adhesive layer can be formed in the following manner. That is, (i) it is coated on a silicone resin-treated polyethylene terephthalate film (manufactured by Mitsubishi Chemical POLYESTER FILM Co., thickness: 38 μm) and heated at 155 °C for 1 minute to form an adhesive layer with a dried thickness of 20 μm, and (ii) this adhesive layer is transcribed (transferred) from the polyethylene terephthalate film to the optical film B, thereby forming the adhesive layer. The evaluation laminate G was produced in the same manner as in Example 1 except for the above.

[0216] [Comparative Example 2]

[0217] An evaluation laminate H was produced in the same manner as in Example 1 except that the thickness of the glass film was 50 μm and the adhesive layer used in the second optical film B was an adhesive layer (thickness: 20 μm) composed of the adhesive prepared in Production Example 3.

[0218] [Comparative Example 3]

[0219] An evaluation laminate I was produced in the same manner as in Example 1 except that the thickness of the adhesive layer composed of the adhesive prepared in Production Example 4 was 250 μm.

[0220] (Evaluation)

[0221] The drop ball test was conducted on the evaluation laminates obtained in Examples 1 to 6 and Comparative Examples 1 to 3.

[0222] The drop ball test means that, as Figure 5 shown, on a glass plate 820 with a thickness of 10 mm disposed on the measurement table 810, the evaluation laminate S (collective name for evaluation laminates A to I) is disposed, and a 130 g iron ball B is vertically dropped from a height L onto the evaluation laminate S to measure the height L at which the glass film of the evaluation laminate S breaks. The evaluation laminate S is disposed on the glass plate 820 with the second optical film B on the side of the glass plate 820.

[0223] The drop ball test was conducted 3 times for each of the evaluation laminates A to I, and then the average value of the 3 heights L at which the glass film broke was obtained. In addition, a case where the average value of the 3 times was less than 17 mm was judged as × (unqualified), a case where it was 17 mm or more and less than 34 mm was judged as 〇 (qualified), and a case where it was 34 mm or more was judged as ◎ (qualified). This reference value was set based on the inventor's empirical values. The results of the drop ball test are shown in Figure 6 and Figure 7It should be noted that the maximum value of the height L is 100 mm, and no tests have been conducted at a higher height.

[0224] As Figure 6 and Figure 7 shown, whether the ball drop test is qualified depends to a large extent on the thickness of the adhesive layer on the B side of the second optical film (the adhesive layer composed of the adhesive prepared in Production Example 4), and the influence of the thickness of other layers is relatively small. It can also be known that if the adhesive layer on the B side of the second optical film is too thin or too thick, the result is poor, and there is an optimal value (50 μm or more and 200 μm or less). These are all facts unknown before and are new knowledge obtained by the inventor.

[0225] In this way, it can be confirmed that if the thickness of the adhesive layer on the B side of the second optical film is 50 μm or more and 200 μm or less, the glass film can be prevented from cracking regardless of whether the thickness of the glass film is 50 μm or 100 μm.

[0226] As mentioned above, although the preferred embodiments and the like have been described in detail, it is not limited to the above-described embodiments and the like. Various modifications and substitutions can be made to the above-described embodiments as long as they do not deviate from the scope described in the claims for patent application.

[0227] For example, in the case of the optical laminate 3 and the like, the liquid crystal cell 30 is illustrated. However, instead of the liquid crystal cell 30, an organic EL (Organic Electro-Luminescence) cell, a micro LED (Light Emitting Diode) cell, or the like can also be used. For example, in the case of an optical laminate including an organic EL cell, an antireflection film (for antiglare, anti-reflection, etc.) can be provided instead of the first polarizing plate 13, and a substrate made of resin can be provided instead of the second polarizing plate 23.

[0228] This international application claims priority based on Japanese Patent Application No. 2019-066163 filed on March 29, 2019, and incorporates the entire content of Japanese Patent Application No. 2019-066163 into this international application.

Claims

1. An optical film stack, comprising: a first optical film having a first adhesive layer and disposed on the viewing side of an optical element through the first adhesive layer; and a second optical film having a second adhesive layer and disposed on the back side of the optical element through the second adhesive layer, wherein a first glass film with a thickness of 50 μm or more and 150 μm or less is provided on the surface of the viewing side of the first optical film, the thickness of the second adhesive layer is 50 μm or more and 200 μm or less, and the thickness of the second adhesive layer is different from the thickness of the first adhesive layer.

2. The optical film stack according to claim 1, wherein the first optical film has a first adhesive layer sequentially disposed on the optical element side of the first glass film and a first polarizing plate having a first polarizer and a first protective film, the second optical film includes a second polarizing plate having a second polarizer.

3. The optical film stack according to claim 2, wherein the first protective film is disposed on the first adhesive layer side of the first polarizer.

4. The optical film stack according to claim 2 or 3, wherein the first optical film further includes a first retardation layer.

5. The optical film stack according to claim 4, wherein the first retardation layer is disposed on the side of the first polarizing plate opposite to the first adhesive layer.

6. The optical film stack according to claim 2 or 3, wherein the second optical film includes a second adhesive layer and a second glass film sequentially disposed on the side of the second polarizing plate opposite to the optical element.

7. The optical film stack according to claim 6, wherein the second optical film includes an optical layer disposed on the side of the second glass film opposite to the second adhesive layer.

8. The optical film stack according to claim 2 or 3, wherein the second optical film further includes a second retardation layer.

9. The optical film stack according to claim 2 or 3, wherein the second optical film further includes an optical layer disposed on at least one side of the second polarizing plate.

10. The optical film stack according to claim 2 or 3, wherein the first polarizing plate has a rectangular shape having a long side and a short side, the absorption axis direction of the first polarizer is substantially parallel to the short side.

11. The optical film stack according to claim 10, wherein the second polarizing plate has a rectangular shape having a long side and a short side, the absorption axis direction of the second polarizer is substantially parallel to the long side.

12. The optical film stack according to claim 2 or 3, wherein the first polarizing plate has a rectangular shape having a long side and a short side, the absorption axis direction of the first polarizer is substantially parallel to the long side.

13. The optical film stack according to claim 12, wherein the second polarizing plate has a rectangular shape having a long side and a short side, the absorption axis direction of the second polarizer is substantially parallel to the short side.

14. An optical laminate, sequentially comprising from the viewing side: the first optical film of the optical film stack according to any one of claims 1 to 13; an optical element; and The second optical film of the optical film stack according to any one of claims 1 to 13.

15. The optical laminate according to claim 14, wherein, the optical element is an inlaid liquid crystal element.

16. The optical laminate according to claim 14, wherein, the optical laminate is applied to an image display device that requires drug resistance.

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