Optical laminate and image display device

Abstract

The present invention provides an optical laminate in which crack formation and propagation caused by exposure to temperature changes are suppressed. An optical laminate according to an embodiment of the present invention includes a polarizing film, a first pressure-sensitive adhesive sheet, and a retardation film in this order. The ratio G1'(25°C) / T1 of a storage modulus G1'(25°C) of the first pressure-sensitive adhesive sheet at 25°C to a thickness T1 of the first pressure-sensitive adhesive sheet is 20.0 kPa / μm or more. The ratio G1'(85°C) / T1 of the storage modulus G1'(85°C) of the first pressure-sensitive adhesive sheet at 85°C to the thickness T1 is 15.0 kPa / μm or less.

Description

Optical laminates and image display devices

[0001] This invention relates to an optical laminate and an image display device.

[0002] In recent years, image display devices, such as liquid crystal displays and electroluminescent (EL) displays (e.g., organic EL displays and inorganic EL displays), have become rapidly widespread. Image display devices generally comprise an optical laminate containing optical substrates such as polarizing films and phase difference films. In an optical laminate containing multiple optical substrates, a bonding layer is usually placed between adjacent optical substrates to join them together. An example of a bonding layer is an adhesive sheet formed from an adhesive composition. Patent Document 1 discloses an example of an optical laminate comprising an adhesive sheet and optical substrates.

[0003] Japanese Patent Publication No. 2020-140212

[0004] According to the inventors' research, in an optical laminate in which an adhesive sheet is placed between a polarizing film and a phase difference film, cracks tend to occur and elongate when exposed to temperature changes.

[0005] The present invention aims to provide an optical laminate in which the occurrence and elongation of cracks when exposed to temperature changes are suppressed.

[0006] [1] An optical laminate according to an embodiment of the present invention comprises a polarizing film, a first adhesive sheet, and a phase difference film in this order, wherein the ratio G1'(25°C) / T1 of the storage modulus of the first adhesive sheet at 25°C to the thickness T1 of the first adhesive sheet is 20.0 kPa / μm or more, and the ratio G1'(85°C) / T1 of the storage modulus of the first adhesive sheet at 85°C to the thickness T1 is 15.0 kPa / μm or less. [2] In the optical laminate described in [1] above, the ratio G1'(25°C) / T1 may be between 40.0 kPa / μm and 100.0 kPa / μm. [3] In the optical laminate described in [1] or [2] above, the ratio G1'(85°C) / T1 may be 10.0 kPa / μm or less. [4] In the optical laminate described in any of [1] to [3] above, the thickness T1 may be less than 10 μm. [5] The optical laminate described in any of [1] to [4] above may further include a second adhesive sheet located on the opposite side of the polarizing film from the phase difference film, and the ratio of the storage modulus G2'(85°C) of the second adhesive sheet at 85°C to the thickness T2 of the second adhesive sheet, G2'(85°C) / T2, may be 2.0 kPa / μm or more. [6] In the optical laminate described in any of [1] to [5] above, the polarizing film may include a polarizer, and the thickness of the polarizer may be 10 μm or less. [7] In the optical laminate described in [6] above, the polarizing film may further include a protective film. [8] In the optical laminate described in any of [1] to [7] above, the phase difference film may include a first liquid crystal alignment solidification layer and a second liquid crystal alignment solidification layer. [9] In the optical laminate described in [8] above, the thickness of at least one layer selected from the group consisting of the first liquid crystal alignment solidification layer and the second liquid crystal alignment solidification layer may be 10 μm or less.

[10] In the optical laminate described in any of [1] to [9] above, the first adhesive sheet may include a crosslinked base polymer.

[11] In the optical laminate described in

[10] above, the base polymer may be a (meth)acrylic polymer.

[12] In the optical laminate described in

[10] or

[11] above, the monomer component constituting the base polymer may include an aromatic ring-containing monomer.

[13] In the optical laminate described in

[12] above, the aromatic ring-containing monomer may include phenoxybenzyl acrylate.

[14] In the optical laminate described in

[12] or

[13] above, the content of the aromatic ring-containing monomer in the monomer component may be 80% by weight or more.

[15] The optical laminate described in any of [1] to

[14] above may have a shape other than rectangular.

[16] An image display device according to an embodiment of the present invention comprises an optical laminate described in any of [1] to

[15] above.

[0007] According to embodiments of the present invention, it is possible to provide an optical laminate in which the occurrence and elongation of cracks when exposed to temperature changes is suppressed.

[0008] This is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. This is a schematic plan view of an optical laminate according to one embodiment of the present invention. This is a schematic plan view of an optical laminate according to one embodiment of the present invention. This is a schematic plan view of an optical laminate according to one embodiment of the present invention. This is a schematic plan view of an optical laminate according to one embodiment of the present invention. This is a schematic plan view of an optical laminate according to one embodiment of the present invention. This is a schematic cross-sectional view of an image display device according to one embodiment of the present invention. This is a graph showing the relationship between ratio G1' (25°C) / T1 and ratio G1' (85°C) / T1 for the first adhesive sheet used in the examples and comparative examples.

[0009] [Regarding Terminology] In this specification, where the term "weight" appears, it may be interpreted as "mass," which is the commonly used SI unit for weight. The reverse is also true.

[0010] In this specification, the expression "(meth)acrylic" means "acrylic and / or methacrylic," the expression "(meth)acrylate" means "acrylate and / or methacrylate," the expression "(meth)allyl" means "allyl and / or methallyl," and the expression "(meth)acrolein" means "acrolein and / or metacrolein."

[0011] In this specification, the term "liquid crystal alignment solidification layer" includes both the first liquid crystal alignment solidification layer and the second liquid crystal alignment solidification layer. Similarly, the term "protective film" includes both the first protective film and the second protective film.

[0012] In this specification, with respect to the refractive index (nx, ny, nz), "nx" is the refractive index in the direction in which the refractive index is maximum in the plane (i.e., in the direction of the slow axis), "ny" is the refractive index in the direction perpendicular to the slow axis in the plane (i.e., in the direction of the fast axis), and "nz" is the refractive index in the thickness direction. In this specification, nx, ny, and nz are values ​​for light with a wavelength of 550 nm. In this specification, the average refractive index is calculated by (nx + ny + nz) / 3.

[0013] In this specification, with respect to the in-plane phase difference (Re), "Re(λ)" is the in-plane phase difference of the film measured with light of wavelength λ nm at 23°C. For example, "Re(550)" is the in-plane phase difference of the film measured with light of wavelength 550 nm at 23°C. Re(λ) can be calculated by the formula: Re = (nx - ny) × d, where d (nm) is the thickness of the film.

[0014] In this specification, with respect to the phase difference in the thickness direction (Rth), "Rth(λ)" is the phase difference in the thickness direction of the film measured with light of wavelength λ nm at 23°C. For example, "Rth(550)" is the phase difference in the thickness direction of the film measured with light of wavelength 550 nm at 23°C. Rth(λ) can be calculated by the formula: Rth = (nx - nz) × d, where the thickness of the film is d (nm).

[0015] In this specification, the "Nz coefficient" is determined by Nz = Rth / Re.

[0016] In this specification, when an angle is mentioned, unless otherwise specified, that angle includes angles in both clockwise and counterclockwise directions.

[0017] ≪≪1. Optical Laminate≫≫ An optical laminate according to an embodiment of the present invention comprises a polarizing film, a first adhesive sheet, and a phase difference film in this order. The ratio of the storage modulus G1'(25°C) of the first adhesive sheet at 25°C to the thickness T1 of the first adhesive sheet, G1'(25°C) / T1, is 20.0 kPa / μm or more. Furthermore, the ratio of the storage modulus G1'(85°C) of the first adhesive sheet at 85°C to the thickness T1 of the first adhesive sheet, G1'(85°C) / T1, is 15.0 kPa / μm or less.

[0018] Conventionally, optical laminates are known in which a polarizing film and a phase difference film are bonded together via an adhesive layer. In these optical laminates, when the polarizing film (specifically, the polarizers in the polarizing film) shrinks under high-temperature conditions, the shrinkage stress is easily transmitted to the phase difference film, which tends to cause a shift in the phase difference value.

[0019] According to the inventors' studies, using an adhesive sheet instead of an adhesive layer tends to suppress the shift in phase difference values ​​under high-temperature conditions. However, optical laminates using adhesive sheets tend to develop and expand cracks when exposed to temperature changes. In particular, cracks can occur significantly at the position of the phase difference film in the irregularly shaped portions of optical laminates that have undergone irregular shaping.

[0020] In the optical laminate of this embodiment, a first adhesive sheet whose ratio G1' (25°C) / T1 and ratio G1' (85°C) / T1 satisfy the above numerical range is placed between the polarizing film and the phase difference film. In an optical laminate having this configuration, the occurrence and elongation of cracks when exposed to temperature changes tend to be suppressed.

[0021] In detail, when the ratio G1' (25°C) / T1 of the first adhesive sheet is 20.0 kPa / μm or higher, the phase difference film is less likely to be damaged during the processing of optical laminates, and crack initiation points tend to be less likely to occur.

[0022] Furthermore, because the ratio G1' (85°C) / T1 of the first adhesive sheet is 15.0 kPa / μm or less, even if the polarizing film expands and contracts due to exposure to temperature changes, the stress is less likely to be transmitted to the phase difference film, and the occurrence and elongation of cracks in the phase difference film tend to be suppressed.

[0023] As mentioned above, the ratio G1' (25°C) / T1 is 20.0 kPa / μm or higher, 23.0 kPa / μm or higher, 25.0 kPa / μm or higher, 28.0 kPa / μm or higher, 30.0 kPa / μm or higher, 33.0 kPa / μm or higher, 35.0 kPa / μm or higher, 38.0 kPa / μm or higher, 40.0 kPa / μm or higher, and 42.0 kPa / μm. a / μm or higher, 43.0 kPa / μm or higher, 45.0 kPa / μm or higher, 48.0 kPa / μm or higher, 50.0 kPa / μm or higher, 53.0 kPa / μm or higher, 55.0 kPa / μm or higher, 58.0 kPa / μm or higher, 60.0 kPa / μm or higher, 63.0 kPa / μm or higher, and even 65.0 kPa / μm or higher. The upper limit of ratio G1'(25°C) / T1 is, for example, 150.0 kPa / μm or less, and may also be 130.0 kPa / μm or less, 120.0 kPa / μm or less, 110.0 kPa / μm or less, 100.0 kPa / μm or less, 95.0 kPa / μm or less, 90.0 kPa / μm or less, 85.0 kPa / μm or less, 80.0 kPa / μm or less, 75.0 kPa / μm or less, and even 70.0 kPa / μm or less. In particular, when the ratio G1'(25°C) / T1 of the first adhesive sheet is 100.0 kPa / μm or less, peeling between components in a high-temperature environment tends to be suppressed. The ratio G1' (25°C) / T1 may be between 20.0 kPa / μm and 100.0 kPa / μm, or between 40.0 kPa / μm and 100.0 kPa / μm, or even between 40.0 kPa / μm and 80.0 kPa / μm.

[0024] The ratio G1'(85°C) / T1 is, as described above, 15.0 kPa / μm or less, and may also be 13.0 kPa / μm or less, 12.0 kPa / μm or less, 11.0 kPa / μm or less, 10.0 kPa / μm or less, 9.0 kPa / μm or less, 8.0 kPa / μm or less, 7.5 kPa / μm or less, and even 7.0 kPa / μm or less. The lower limit of the ratio G1'(85°C) / T1 is, for example, 1.0 kPa / μm or more, and may also be 2.0 kPa / μm or more, 3.0 kPa / μm or more, 4.0 kPa / μm or more, 5.0 kPa / μm or more, and even 6.0 kPa / μm or more. The ratio G1' (85°C) / T1 may be between 1.0 kPa / μm and 15.0 kPa / μm, or between 1.0 kPa / μm and 10.0 kPa / μm, or even between 1.0 kPa / μm and 9.0 kPa / μm.

[0025] The ratios G1'(25°C) / T1 and G1'(85°C) / T1 may satisfy the following relation (1), and may also satisfy the following relation (2). In relation (1) and (2), x represents the ratio G1'(25°C) / T1, and y represents the ratio G1'(85°C) / T1. Relations (1) and (2) correspond to the dashed lines (1) and (2) in Figure 10, respectively. y ≤ 0.25x - 2.5 (1) y ≤ 0.25x - 7.5 (2)

[0026] The ratios G1'(25°C) / T1 and G1'(85°C) / T1 may satisfy the following relation (3). In relation (3), x represents the ratio G1'(25°C) / T1, and y represents the ratio G1'(85°C) / T1. Relation (3) corresponds to the dashed line (3) in Figure 10. y ≥ 0.25x - 15 (3)

[0027] Furthermore, as long as the ratio G1'(25°C) / T1 and the ratio G1'(85°C) / T1 satisfy the above-mentioned numerical ranges, the thickness T1, storage modulus G1'(25°C), and storage modulus G1'(85°C) of the first adhesive sheet are not particularly limited.

[0028] The thickness T1 of the first adhesive sheet is, for example, 50 μm or less, and may be 30 μm or less, 20 μm or less, 15 μm or less, 10 μm or less, less than 10 μm, 8 μm or less, 6 μm or less, and even 5 μm or less. The lower limit of the thickness T1 is, for example, 1 μm or more, and may be 2 μm or more, 3 μm or more, and even 4 μm or more. The thickness T1 is preferably 3 μm or more and less than 10 μm, and particularly preferably 4 μm to 6 μm.

[0029] The storage modulus G1' (25°C) of the first adhesive sheet at 25°C is, for example, 100 kPa or more, and may be 130 kPa or more, 150 kPa or more, 180 kPa or more, 200 kPa or more, 230 kPa or more, 250 kPa or more, 280 kPa or more, 300 kPa or more, and even 330 kPa or more. The storage modulus G1' (25°C) is, for example, 700 kPa or less, and may be 650 kPa or less, 600 kPa or less, 550 kPa or less, 530 kPa or less, 500 kPa or less, 480 kPa or less, 450 kPa or less, 430 kPa or less, 400 kPa or less, 380 kPa or less, and even 350 kPa or less. The storage modulus G1' (at 25°C) may be 100 kPa to 600 kPa, 200 kPa to 550 kPa, or even 300 kPa to 500 kPa.

[0030] The storage modulus G1' (85°C) of the first adhesive sheet at 85°C is, for example, 100 kPa or less, and may be 80 kPa or less, 60 kPa or less, 55 kPa or less, 50 kPa or less, 45 kPa or less, 43 kPa or less, 40 kPa or less, 38 kPa or less, and even 35 kPa or less. The storage modulus G1' (85°C) is, for example, 10 kPa or more, and may be 15 kPa or more, 20 kPa or more, 25 kPa or more, 28 kPa or more, 30 kPa or more, 33 kPa or more, and even 34 kPa or more. The above storage modulus G1' (85°C) is preferably between 10 kPa and 100 kPa, and more preferably between 30 kPa and 50 kPa.

[0031] The storage modulus G1' (25°C) and storage modulus G1' (85°C) mentioned above can be determined by the following method. First, a measurement sample made of the material constituting the first adhesive sheet is prepared. The shape of the measurement sample is disc-shaped. The measurement sample has a base diameter of 8 mm and a thickness of 1 mm. The measurement sample may also be a disc-shaped cutout of a laminate in which multiple first adhesive sheets are stacked. Next, dynamic viscoelasticity measurement is performed on the measurement sample. For dynamic viscoelasticity measurement, for example, TA Instruments' "ARES-G2" can be used. From the results of the dynamic viscoelasticity measurement, the storage modulus G1' (25°C) at 25°C and the storage modulus G1' (85°C) at 85°C can be determined. The conditions for dynamic viscoelasticity measurement are as follows: Measurement conditions Frequency: 1 Hz Deformation mode: Torsion Measurement temperature: -70°C to 150°C Heating rate: 5°C / min

[0032] ≪1-1. Overall Structure of the Optical Laminate≫ Figure 1 is a typical schematic cross-sectional view of an optical laminate according to an embodiment of the present invention. The optical laminate 100 shown in Figure 1 comprises a polarizing film 20, a first adhesive sheet 10, and a phase difference film 30 in this order. The polarizing film 20 is located, for example, on the viewing side of the phase difference film 30. Preferably, the polarizing film 20 and the phase difference film 30 are bonded together via the first adhesive sheet 10.

[0033] The polarizing film 20 preferably includes a polarizer and further includes a protective film. In the example shown in Figure 1, the polarizing film 20 includes a first protective film 22 and a second protective film 23, with the polarizer 21 positioned between these protective films 22 and 23. The polarizing film 20 shown in Figure 1 is a so-called double-protection polarizing film. However, the polarizing film 20 does not necessarily have to include one of the first protective film 22 and the second protective film 23 (especially the second protective film 23), and may be a so-called single-protection polarizing film. The polarizing film 20 may not include a protective film and may consist of the polarizer 21 alone.

[0034] In the polarizing film 20, the first protective film 22 is located closer to the viewing side than the second protective film 23, for example. The second protective film 23 is in contact with the first pressure-sensitive adhesive sheet 10, for example.

[0035] As shown in Figure 1, the retardation film 30 preferably includes a first liquid crystal alignment solidified layer 31 and a second liquid crystal alignment solidified layer 32. The first liquid crystal alignment solidified layer 31 is located closer to the viewing side than the second liquid crystal alignment solidified layer 32, for example, and is in contact with the first pressure-sensitive adhesive sheet 10.

[0036] As shown in Figure 1, the optical laminate 100 may further include a second pressure-sensitive adhesive sheet (panel-side pressure-sensitive adhesive sheet) 40. The second pressure-sensitive adhesive sheet 40 is located on the opposite side of the polarizing film 20 relative to the retardation film 30. For example, the second pressure-sensitive adhesive sheet 40 is in contact with the second liquid crystal alignment solidified layer 32 of the retardation film 30. When the optical laminate 100 includes the second pressure-sensitive adhesive sheet 40, the optical laminate 100 can be attached to an image display cell via the second pressure-sensitive adhesive sheet 40. The optical laminate 100 shown in Figure 1 typically has a configuration in order from the viewing side: first protective film 22 / polarizer 21 / second protective film 23 / first pressure-sensitive adhesive sheet 10 / first liquid crystal alignment solidified layer 31 / second liquid crystal alignment solidified layer 32 / second pressure-sensitive adhesive sheet 40.

[0037] The optical laminate 100 may further include a release liner (not shown) disposed on the second pressure-sensitive adhesive sheet 40. In this case, the optical laminate 100 can be bonded to the image display cell by peeling the release liner off the optical laminate 100 and placing the image display cell on the exposed surface of the second pressure-sensitive adhesive sheet 40.

[0038] The optical laminate according to the embodiment of the present invention can adopt any appropriate configuration as long as it includes a polarizing film, a first pressure-sensitive adhesive sheet, and a retardation film in this order, and is typically the configuration shown in FIG. 1 above.

[0039] Hereinafter, the constituent elements of the optical laminate will be described.

[0040] ≪1-2. First Adhesive Sheet≫ The first adhesive sheet is usually composed of an adhesive. The first adhesive sheet may contain a crosslinked base polymer and is typically formed by curing an adhesive composition containing a base polymer.

[0041] <1-2-1. Adhesive Composition> (1-2-1-a. Base Polymer) The base polymer contained in the adhesive composition may be a (meth)acrylic polymer. In this case, the first adhesive sheet will be a (meth)acrylic adhesive sheet. A (meth)acrylic polymer means a polymer in which the main constituent unit of the base polymer is a (meth)acrylate unit. The main constituent unit means the constituent unit that has the largest weight percentage among all constituent units of the base polymer. The weight percentage of the main constituent unit may be, for example, 50% or more, 60% or more, 65% or more, 70% or more, 75% or more, 80% or more, 85% or more, 90% or more, and even 92% or more. The upper limit of this percentage may be, for example, 100% or less, and 99% or less.

[0042] The polymer structure of the base polymer may be any of the following: random copolymer structure, block copolymer structure, graft copolymer structure, etc. The base polymer is obtained by polymerization of monomer components.

[0043] The monomer component preferably includes an aromatic ring-containing monomer. The aromatic ring-containing monomer may be one type or two or more types.

[0044] As aromatic ring-containing monomers, compounds containing at least one aromatic ring and at least one ethylenically unsaturated group in one molecule can be used.

[0045] Examples of ethylenically unsaturated groups include (meth)acryloyl groups, vinyl groups, and (meth)allyl groups. From the viewpoint of better exhibiting the effects of the present invention, (meth)acryloyl groups are preferred as ethylenically unsaturated groups, and acryloyl groups are more preferred. Therefore, a preferred embodiment of the aromatic ring-containing monomer is an aromatic ring-containing (meth)acrylate.

[0046] From the viewpoint of suppressing a decrease in the flexibility of the adhesive, the aromatic ring-containing monomer is preferably a compound in which the number of ethylenically unsaturated groups in one molecule is 1 (i.e., a monofunctional monomer).

[0047] The number of aromatic rings contained in one molecule of aromatic ring-containing monomer is, for example, 1 to 16, but may also be 2 to 12, 2 to 8, 2 to 6, 2 to 4, 2 to 3, or 2.

[0048] The aromatic ring contained in the aromatic ring-containing monomer may be a hydrocarbon ring such as a benzene ring (which may be a benzene ring that constitutes part of a biphenyl or fluorene structure); a condensed ring of a naphthalene ring, indene ring, azulene ring, anthracene ring, or phenanthrene ring; or a heterocycle such as a pyridine ring, pyrimidine ring, pyridazine ring, pyrazine ring, triazine ring, pyrrole ring, pyrazole ring, imidazole ring, triazole ring, oxazole ring, isoxazole ring, thiazole ring, or thiophene ring. Examples of heteroatoms contained in such heterocycles include nitrogen, sulfur, and oxygen, with nitrogen and sulfur being preferred. The aromatic ring-containing monomer may have a structure in which one or more carbon rings and one or more heterocycles are fused, such as a dinaphthothiophene structure.

[0049] The aromatic ring contained in the aromatic ring-containing monomer may have substituents on its ring constituent atoms. There may be only one substituent or two or more substituents. Examples of substituents include alkyl groups, alkoxy groups, aryloxy groups, hydroxyl groups, halogen atoms, hydroxyalkyl groups, hydroxyalkyloxy groups, and glycidyloxy groups.

[0050] The aromatic ring and the ethylenically unsaturated group in the aromatic ring-containing monomer may be directly bonded or bonded via a linking group. Examples of such linking groups include groups containing at least one structure selected from the group consisting of alkylene groups, oxyalkylene groups, poly(oxyalkylene) groups, phenyl groups, alkylphenyl groups, alkoxyphenyl groups, groups in which one or more hydrogen atoms are substituted with hydroxyl groups (e.g., hydroxyalkylene groups), oxy groups (-O- groups), and thiooxy groups (-S- groups). In terms of being able to better express the effects of the present invention, such linking groups preferably include groups containing at least one structure selected from the group consisting of alkylene groups, oxyalkylene groups, and poly(oxyalkylene) groups. The number of carbon atoms in the alkylene group and oxyalkylene group is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 to 2. The number of repeating oxyalkylene units in the poly(oxyalkylene) group is preferably 2 to 3.

[0051] From the viewpoint of better expressing the effects of the present invention, the aromatic ring-containing monomer may include monomers having two or more aromatic rings in one molecule (hereinafter sometimes referred to as "multiple aromatic ring-containing monomers"). Examples of multiple aromatic ring-containing monomers include monomers having a structure in which two or more non-condensed aromatic rings are linked via linking groups, monomers having a structure in which two or more non-condensed aromatic rings are directly chemically bonded, monomers having a condensed aromatic ring structure, monomers having a fluorene structure, monomers having a dinaphthothiophene structure, and monomers having a dibenzothiophene structure.

[0052] Examples of linking groups that a monomer containing multiple aromatic rings may have include an oxy group (-O-), a thiooxy group (-S-), and an oxyalkylene group (-O-(CH2)). n - group, where n is 1 to 3, preferably 1), thiooxyalkylene group (-S-(CH2) n - group, where n is 1 to 3, preferably 1), linear alkylene group (-(CH2) n- Groups, where n is 1 to 6, preferably 1 to 3), oxyalkylene groups, thiooxyalkylene groups, and linear alkylene groups in which the alkylene group is partially halogenated or fully halogenated are examples.

[0053] Examples of monomers having a structure in which two or more non-condensed aromatic rings are linked via linking groups include phenoxybenzyl (meth)acrylate (e.g., m-phenoxybenzyl (meth)acrylate), thiophenoxybenzyl (meth)acrylate, and benzylbenzyl (meth)acrylate.

[0054] Examples of monomers having a structure in which two or more non-condensed aromatic rings are directly chemically bonded include biphenyl structure-containing (meth)acrylates, triphenyl structure-containing (meth)acrylates, and vinyl group-containing biphenyls. Specific examples include o-phenylphenol (meth)acrylate and biphenylmethyl (meth)acrylate.

[0055] Examples of monomers having a condensed aromatic ring structure include naphthalene ring-containing (meth)acrylate, anthracene ring-containing (meth)acrylate, vinyl group-containing naphthalene, and vinyl group-containing anthracene. Specific examples include 1-naphthylmethyl (meth)acrylate (also known as 1-naphthalenemethyl (meth)acrylate), hydroxyethylated β-naphthol acrylate, 2-naphthoethyl (meth)acrylate, 2-naphthoxyethyl acrylate, and 2-(4-methoxy-1-naphthoxy)ethyl (meth)acrylate.

[0056] Examples of monomers having a fluorene structure include 9,9-bis(4-hydroxyphenyl)fluorene (meth)acrylate and 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene (meth)acrylate. Since monomers having a fluorene structure include a structural portion in which two benzene rings are directly chemically bonded, they can be included in the concept of monomers having a structure in which two or more non-condensed aromatic rings are directly chemically bonded.

[0057] Examples of monomers having a dinaphthothiophene structure include (meth)acryloyl group-containing dinaphthothiophene, vinyl group-containing dinaphthothiophene, and (meth)allyl group-containing dinaphthothiophene. A specific example is (meth)acryloyloxymethyl dinaphthothiophene (for example, CH2CH(R) at the 5th or 6th position of the dinaphthothiophene ring). 1 ) Compounds with a structure in which C(O)OCH2- is bonded, R 1 (R) is a hydrogen atom or a methyl group. ) (meth)acryloyloxyethyl dinaphthothiophene (for example, CH2CH(R) at the 5th or 6th position of the dinaphthothiophene ring) 1 )C(O)OCH(CH3)- or CH2CH(R 1 Compounds with a structure in which C(O)OCH2CH2- is bonded, R 1 The group is a hydrogen atom or a methyl group. Examples include vinyl dinaphthothiophene (for example, a compound in which a vinyl group is bonded to the 5th or 6th position of the naphthothiophene ring) and (meth)allyloxydinaphthothiophene. Note that monomers having a dinaphthothiophene structure can also be included in the concept of monomers having a condensed aromatic ring structure by including a naphthalene structure or by having a structure in which a thiophene ring and two naphthalene structures are condensed.

[0058] Examples of monomers having a dibenzothiophene structure include (meth)acryloyl group-containing dibenzothiophene and vinyl group-containing dibenzothiophene. Since monomers having a dibenzothiophene structure have a structure in which a thiophene ring and two benzene rings are condensed, they can be included in the concept of monomers having a condensed aromatic ring structure. Note that neither the dinaphthothiophene structure nor the dibenzothiophene structure corresponds to a structure in which two or more non-condensed aromatic rings are directly chemically bonded.

[0059] As the aromatic ring-containing monomer, a monomer having one aromatic ring in one molecule may be used. Monomers having one aromatic ring in one molecule can be useful, for example, for adjusting the flexibility and adhesive properties of adhesives, and improving transparency.

[0060] Examples of monomers having one aromatic ring in one molecule include carbon aromatic ring-containing (meth)acrylates such as benzyl (meth)acrylate, methoxybenzyl (meth)acrylate, phenyl (meth)acrylate, ethoxylated phenol (meth)acrylate, phenoxypropyl (meth)acrylate, phenoxybutyl (meth)acrylate, cresyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, chlorobenzyl (meth)acrylate, etc.; 2-(4,6-dibromo-2-s-butylphenoxy)ethyl (meth)acrylate, 2-(4,6-dibromo-2-isopropylphenoxy)ethyl (meth)acrylate, Examples include bromine-substituted aromatic ring-containing (meth)acrylates such as 6-(4,6-dibromo-2-s-butylphenoxy)hexyl (meth)acrylate, 6-(4,6-dibromo-2-isopropylphenoxy)hexyl (meth)acrylate, 2,6-dibromo-4-nonylphenyl acrylate, and 2,6-dibromo-4-dodecylphenyl acrylate; carbon aromatic ring-containing vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, and tert-butylstyrene; and compounds having vinyl substituents on heteroaromatic rings such as N-vinylpyridine, N-vinylpyrimidine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, and N-vinyloxazole.

[0061] From the viewpoint of better expressing the effects of the present invention, among the above, phenoxybenzyl (meth)acrylate, 1-naphthylmethyl (meth)acrylate, ethoxylated o-phenylphenol (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, 6-(meth)acryloyloxymethyl dinaphthothiophene, 5-(meth)acryloyloxyethyl dinaphthothiophene, 6-(meth)acryloyloxyethyl dinaphthothiophene, 6-vinyl dinaphthothiophene, and 5-vinyl dinaphthothiophene are particularly preferred as aromatic ring-containing monomers. The aromatic ring-containing monomer preferably contains phenoxybenzyl (meth)acrylate, and more preferably contains phenoxybenzyl acrylate. Aromatic ring-containing monomers such as phenoxybenzyl (meth)acrylate are suitable for adjusting the ratio G1' (25°C) / T1 and ratio G1' (85°C) / T1 of the first adhesive sheet to appropriate values.

[0062] The content of aromatic ring-containing monomers in the monomer component is, for example, 30% by weight or more, and may be 50% by weight or more, 60% by weight or more, 70% by weight or more, 75% by weight or more, 78% by weight or more, 80% by weight or more, 83% by weight or more, 85% by weight or more, 86% by weight or more, and even 87% by weight or more. The above content is, for example, 99% by weight or less, and may be 98% by weight or less, 95% by weight or less, 93% by weight or less, 92% by weight or less, 91% by weight or less, and even 90% by weight or less. The above content is preferably 78% by weight to 92% by weight, more preferably 80% by weight to 91% by weight, and even more preferably 86% by weight to 90% by weight.

[0063] The monomer component may include monomers copolymerizable with aromatic ring-containing monomers (hereinafter sometimes referred to as "copolymerized monomers"). There may be only one copolymerized monomer or two or more copolymerized monomers. Examples of copolymerized monomers include alkyl (meth)acrylates, hydroxyl group-containing monomers, carboxyl group-containing monomers, and amide group-containing monomers.

[0064] The number of carbon atoms in the alkyl group in alkyl (meth)acrylate is, for example, 1 to 30. The alkyl group may be linear, branched, or cyclic. Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl, hexyl, cyclohexyl, heptyl, 2-ethylhexyl, isooctyl, nonyl, decyl, isodecyl, dodecyl, isomiristyl, lauryl, tridecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl groups. There may be only one alkyl (meth)acrylate or two or more alkyl (meth)acrylates. From the viewpoint of better exhibiting the effects of the present invention, butyl acrylate is preferred as the alkyl (meth)acrylate.

[0065] The content of alkyl (meth)acrylate in the monomer component is, for example, 70% by weight or less, and may be 50% by weight or less, 40% by weight or less, 30% by weight or less, 25% by weight or less, 22% by weight or less, 20% by weight or less, 17% by weight or less, 15% by weight or less, 14% by weight or less, 13% by weight or less, and even 12% by weight or less. The above content may be, for example, 1% by weight or more, 2% by weight or more, 5% by weight or more, 6% by weight or more, 7% by weight or more, and even 8% by weight or more. The above content is preferably 7% by weight to 20% by weight, more preferably 8% by weight to 15% by weight, and even more preferably 8% by weight to 12% by weight. The monomer component does not have to contain alkyl (meth)acrylate.

[0066] Hydroxyl group-containing monomers are compounds that contain a hydroxyl group in their structure and also contain a polymerizable unsaturated double bond such as a (meth)acryloyl group or a vinyl group. Hydroxyl group-containing monomers may also be hydroxyl group-containing (meth)acrylates. Examples of hydroxyl group-containing (meth)acrylates include hydroxyl group-containing alkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate; and hydroxyl group-containing cycloalkyl (meth)acrylates such as (4-hydroxymethylcyclohexyl)-methyl acrylate. Among these, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred.

[0067] The content of hydroxyl group-containing monomers in the monomer component is, for example, 0.1% by weight or more, and may be 0.5% by weight or more, 0.8% by weight or more, 1.0% by weight or more, 1.1% by weight or more, 1.2% by weight or more, and even 1.3% by weight or more. The above content is, for example, 10% by weight or less, and may be 7% by weight or less, 5% by weight or less, 4% by weight or less, 3% by weight or less, 2% by weight or less, and even 1.8% by weight or less. The monomer component does not have to contain hydroxyl group-containing monomers.

[0068] A carboxyl group-containing monomer is a compound that contains a carboxyl group in its structure and also contains a polymerizable unsaturated double bond such as a (meth)acryloyl group or a vinyl group. A carboxyl group-containing monomer may also be a carboxyl group-containing (meth)acrylate. Examples of carboxyl group-containing (meth)acrylates include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid.

[0069] The content of carboxyl group-containing monomers in the monomer component may be, for example, 10% by weight or less, 7% by weight or less, 5% by weight or less, or even 3% by weight or less. The above content may be, for example, 0.1% by weight or more, or 0.5% by weight or more. The monomer component does not have to contain carboxyl group-containing monomers.

[0070] Amide group-containing monomers are compounds that contain an amide group in their structure and also contain polymerizable unsaturated double bonds such as (meth)acryloyl groups and vinyl groups. Amide group-containing monomers may also be amide group-containing (meth)acrylates. Examples of amide group-containing (meth)acrylates include acrylamide monomers such as (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, and mercaptoethyl(meth)acrylamide; N-acryloyl heterocyclic monomers such as N-(meth)acryloylmorpholin, N-(meth)acryloylpiperidine, and N-(meth)acryloylpyrrolidine; and N-vinyl group-containing lactam monomers such as N-vinylpyrrolidone and N-vinyl-ε-caprolactam.

[0071] The content of amide group-containing monomers in the monomer component may be, for example, 10% by weight or less, 7% by weight or less, 5% by weight or less, or even 3% by weight or less. The above content may be, for example, 0.1% by weight or more, or 0.5% by weight or more. The monomer component does not have to contain amide group-containing monomers.

[0072] In addition to the above, other copolymer monomers include, for example, acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride; caprolactone adducts of acrylic acid; sulfonic acid group-containing monomers such as allyl sulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidepropanesulfonic acid, and sulfopropyl (meth)acrylate; phosphate group-containing monomers such as 2-hydroxyethyl acryloyl phosphate; aminoethyl (meth)acrylate and N,N-dimethylamino Alkylaminoalkyl (meth)acrylates such as ethyl (meth)acrylate and t-butylaminoethyl (meth)acrylate; alkoxyalkyl (meth)acrylates such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate; succinimide monomers such as N-(meth)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, and N-(meth)acryloyl-8-oxyoctamethylenesuccinimide; N-cyclohexylmaleimide, N - Maleimide monomers such as isopropylmaleimide, N-laurylmaleimide, and N-phenylmaleimide; itaconimide monomers such as N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, and N-laurylitaconimide; vinyl monomers such as vinyl acetate and vinyl propionate; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; glycidyl (meth)acrylate Epoxy group-containing (meth)acrylates such as rilate; glycol-based (meth)acrylates such as carbitol (meth)acrylate, ethyl carbitol (meth)acrylate, polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, etc.; (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, silicone (meth)acrylate, etc.Examples of silane monomers containing silicon atoms include 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8-vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, and 10-acryloyloxydecyltriethoxysilane.

[0073] The content of other copolymer monomers in the monomer component may be, for example, 5% by weight or less, 3% by weight or less, or even 1% by weight or less. The monomer component may not contain other copolymer monomers.

[0074] The base polymer is obtained by polymerizing monomer components. The base polymer can be formed by various known polymerization methods, such as solution polymerization, radiation polymerization using electron beams or ultraviolet (UV) light, bulk polymerization, and emulsion polymerization. Polymerization is typically radical polymerization.

[0075] For solution polymerization, known polymerization solvents such as ethyl acetate and toluene can be used as the polymerization solvent. Solution polymerization can be carried out, for example, using a polymerization initiator and under an inert gas stream such as nitrogen. Any suitable polymerization conditions can be adopted as long as they do not impair the effects of the present invention. Such polymerization conditions include, for example, a polymerization temperature of 50°C to 70°C and a polymerization time of 5 to 30 hours.

[0076] Any suitable compound can be used as a polymerization initiator, chain transfer agent, or emulsifier for radical polymerization, as long as it does not impair the effects of the present invention.

[0077] Examples of polymerization initiators include azo-based initiators such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-amidinopropane)dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane]dihydrochloride, 2,2'-azobis(2-methylpropionamidine)disulfate, 2,2'-azobis(N,N'-dimethyleneisobutylamidine), and 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]hydrate (e.g., VA-057 manufactured by Wako Pure Chemical Industries, Ltd.); persulfates such as potassium persulfate and ammonium persulfate; di(2-ethylhexyl)peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, di- Examples of peroxide initiators include sec-butyl peroxydicarbonate, t-butyl peroxyneodecanoate, t-hexyl peroxypivalate, t-butyl peroxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, di(4-methylbenzoyl) peroxide, dibenzoyl peroxide, t-butyl peroxyisobutyrate, 1,1-di(t-hexyl peroxy)cyclohexane, t-butyl hydroperoxide, and hydrogen peroxide; and redox initiators combining peroxides and reducing agents, such as combinations of persulfates and sodium bisulfite, or combinations of peroxides and sodium ascorbate. The polymerization initiator may be one type or two or more types. The amount of polymerization initiator used can be any appropriate amount, as long as it does not impair the effects of the present invention. Such usage amounts are, for example, 0.005 parts by weight to 1 part by weight, or 0.02 parts by weight to 0.5 parts by weight, per 100 parts by weight of the monomer component.

[0078] Examples of chain transfer agents include lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, and 2,3-dimercapto-1-propanol. The chain transfer agent may be used alone or in combination of two or more. The amount of chain transfer agent used can be any appropriate amount, as long as it does not impair the effects of the present invention. For example, such an amount is 0.1 parts by weight or less per 100 parts by weight of the monomer component.

[0079] In radiation polymerization, a base polymer is formed by irradiating monomer components with radiation such as electron beams or ultraviolet (UV) light to promote polymerization. When radiation polymerization is performed using electron beams, the use of a photoinitiator is not particularly necessary. When radiation polymerization is performed using UV light, a photoinitiator may be used due to advantages such as shortening the polymerization time. One type of photoinitiator may be used, or two or more types may be used.

[0080] Examples of photopolymerization initiators include benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, and thioxanthone-based photopolymerization initiators. The amount of photopolymerization initiator used can be any appropriate amount within a range that does not impair the effects of the present invention. Such an amount may be, for example, 0.05 to 1.5 parts by weight, or 0.1 to 1 part by weight, per 100 parts by weight of the monomer component.

[0081] (1-2-1-b. Crosslinking agent) The adhesive composition may contain a crosslinking agent. There may be only one type of crosslinking agent, or there may be two or more types.

[0082] Examples of crosslinking agents that the adhesive composition may contain include isocyanate-based crosslinking agents, peroxide-based crosslinking agents, epoxy-based crosslinking agents, imine-based crosslinking agents, and polyfunctional metal chelates. The adhesive composition preferably contains an isocyanate-based crosslinking agent and / or a peroxide-based crosslinking agent, and more preferably contains an isocyanate-based crosslinking agent.

[0083] As an isocyanate crosslinking agent, a compound having at least two isocyanate groups (isocyanate compound) can be used. Preferably, the number of isocyanate groups in the isocyanate compound is three or more. The upper limit of the number of isocyanate groups is not particularly limited, but is, for example, five. Examples of isocyanate compounds include aromatic isocyanate compounds, alicyclic isocyanate compounds, and aliphatic isocyanate compounds.

[0084] Examples of aromatic isocyanate compounds include phenylenediisocyanate, 2,4-tolylenediisocyanate, 2,6-tolylenediisocyanate, 2,2'-diphenylmethanediisocyanate, 4,4'-diphenylmethanediisocyanate, 4,4'-toluidinediisocyanate, 4,4'-diphenyletherdiisocyanate, 4,4'-diphenyldiisocyanate, 1,5-naphthalenediisocyanate, and xylylenediisocyanate.

[0085] Examples of alicyclic isocyanate compounds include 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated tetramethylxylylene diisocyanate.

[0086] Examples of aliphatic isocyanate compounds include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

[0087] Examples of isocyanate-based crosslinking agents include polymers (dimers, trimers, pentamers, etc.) of the above-mentioned isocyanate compounds, adducts obtained by adding them to polyhydric alcohols such as trimethylolpropane, urea-modified compounds, biuret-modified compounds, allophanate-modified compounds, isocyanurate-modified compounds, carbodiimide-modified compounds, polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, polyisoprene polyols, and urethane prepolymers obtained by adding them to these materials.

[0088] The isocyanate crosslinking agent is preferably an aromatic isocyanate compound and its derivatives, more preferably tolylene diisocyanate and its derivatives, in other words, a tolylene diisocyanate-based (TDI) crosslinking agent. From the viewpoint of reactivity, TDI crosslinking agents are more suitable than xylylene diisocyanate and its derivatives, in other words, xylylene diisocyanate-based (XDI) crosslinking agents. The isocyanate crosslinking agent may also contain polyhydric alcohols and adducts of tolylene diisocyanate as TDI crosslinking agents. A specific example of an adduct is a trimethylolpropane / tolylene diisocyanate trimer adduct.

[0089] Commercially available isocyanate crosslinking agents may be used. Examples of such commercially available products include Millionate MT, Millionate MTL, Millionate MR-200, Millionate MR-400, Coronate L, Coronate HL, Coronate HX (all manufactured by Tosoh Corporation), Takenate D-101E, Takenate D-110N, Takenate D-120N, Takenate D-140N, Takenate D-160N, Takenate D-165N, Takenate D-170HN, Takenate D-178N, Takenate 500, and Takenate 600 (all manufactured by Mitsui Chemicals). Among these, Takenate D-101E and Takenate D110N are preferred.

[0090] The content of isocyanate-based crosslinking agent in the adhesive composition is, for example, 0.01 to 20 parts by weight per 100 parts by weight of the base polymer. The above content may be 0.05 parts by weight or more, 0.10 parts by weight or more, 0.15 parts by weight or more, 0.20 parts by weight or more, 0.25 parts by weight or more, and even 0.30 parts by weight or more. The above content may be 15 parts by weight or less, 13 parts by weight or less, 10 parts by weight or less, 8 parts by weight or less, 5 parts by weight or less, 3 parts by weight or less, 2 parts by weight or less, 1 part by weight or less, and even 0.5 parts by weight or less. The above content may be 0.03 to 1 part by weight, and even 0.05 to 0.5 parts by weight.

[0091] The content of crosslinking agents other than isocyanate-based crosslinking agents (e.g., peroxide-based crosslinking agents) in the adhesive composition is, for example, 2 parts by weight or less, 1 part by weight or less, and even 0.5 parts by weight or less, per 100 parts by weight of the base polymer. The above content is, for example, 0.01 parts by weight or more, and may be 0.05 parts by weight or more, 0.1 parts by weight or more, 0.15 parts by weight or more, and even 0.2 parts by weight or more. The above content may be 0.05 to 1 part by weight, and may be 0.1 to 0.5 parts by weight. The adhesive composition may not contain crosslinking agents other than isocyanate-based crosslinking agents.

[0092] (1-2-1-c. Other Components) The adhesive composition may contain known additives as other components. Any suitable additive can be used as such, as long as it does not impair the effects of the present invention. Examples of such additives include silane coupling agents, solvents, colorants, pigments, powders, dyes, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, softeners, antioxidants, anti-aging agents, light stabilizers, UV absorbers, polymerization inhibitors, inorganic fillers, organic fillers, metal powders, particles, and foils. In addition, a redox system with a reducing agent may be used within a controllable range. The total content of additives is, for example, 10 parts by weight or less, 5 parts by weight or less, or even 1 part by weight or less, per 100 parts by weight of the base polymer.

[0093] <1-2-2. Method for Manufacturing the First Adhesive Sheet> The first adhesive sheet can be formed, for example, by drying a coating film of an adhesive composition provided on a substrate. Heating can be used as a means of drying. A release liner may be used as the substrate. The first adhesive sheet formed on the release liner can be transferred, for example, to other layers that the optical laminate may contain (e.g., a polarizing film or a phase difference film). The substrate may also be other layers that the optical laminate may contain.

[0094] As the release liner, a known film usable when forming an adhesive sheet from an adhesive composition may be used. Examples of release liners include films, paper, woven fabrics, nonwoven fabrics, porous materials, nets, foams, foils, or laminates thereof, composed of resins, paper, fibers, metals, or composite materials thereof. Examples of resins include polyethylene, polypropylene, polybutene, polybutadiene, polymethylpentene, polyvinyl chloride, vinyl chloride copolymer, polyethylene terephthalate, polybutylene terephthalate, polyurethane, and ethylene-vinyl acetate copolymer.

[0095] The thickness of the release liner is, for example, 5 μm to 200 μm, and may be 5 μm to 100 μm. The surface of the release liner may be subjected to various surface treatments as needed, such as mold release treatment, antifouling treatment, and antistatic treatment.

[0096] The drying temperature of the coated film is, for example, 100°C or higher, and may be 110°C or higher, 120°C or higher, 130°C or higher, or even 140°C or higher. The above drying temperature is, for example, 170°C or lower, 160°C or lower, or even 150°C or lower. The drying time of the coated film can be appropriately adjusted according to the composition of the adhesive composition, and may be, for example, 30 seconds to 300 seconds, 40 seconds to 240 seconds, or even 60 seconds to 180 seconds.

[0097] The method for forming the first adhesive sheet from the adhesive composition is not limited to the above examples. For example, the first adhesive sheet may be formed by the following method.

[0098] First, a coating film of the adhesive composition is formed on the substrate. However, the adhesive composition contains a thermal crosslinking agent, a photopolymerization initiator, and a polyfunctional monomer in addition to the base polymer. The thermal crosslinking agent and photopolymerization initiator can be those mentioned above. Next, the coating film is dried to form an adhesive sheet precursor. Heating can be used in combination with drying. Examples of drying temperature and drying time are as described above, but the conditions should not completely cure the coating film. The adhesive sheet precursor may also be formed by adjusting the amount of crosslinking agent incorporated into the adhesive composition. Next, the adhesive sheet precursor is irradiated with light to proceed with a photocuring reaction in which the polyfunctional monomer is used as a photocrosslinking agent, thereby forming a first adhesive sheet. The light is, for example, visible light or ultraviolet light with a wavelength shorter than 450 nm. The formed first adhesive sheet is a layer formed by curing an adhesive composition containing a base polymer, a polyfunctional monomer, a thermal crosslinking agent, and a photopolymerization initiator. Depending on the photocuring conditions and the type and conditions of the process carried out after curing, some photopolymerization initiator may remain in the formed first adhesive sheet. The hardness of the adhesive sheet precursor is usually lower than that of the first adhesive sheet. However, a certain degree of tackiness can be obtained even in the adhesive sheet precursor state. For example, it is possible to form the first adhesive sheet by attaching the adhesive sheet precursor to the object and then proceeding with the photocuring reaction. This method can contribute to improving the anchoring power of the first adhesive sheet to the object.

[0099] A polyfunctional monomer is a compound containing two or more polymerizable functional groups. A polyfunctional monomer may also be a (meth)acrylic monomer. Examples of polyfunctional monomers are monomers having two or more C=C bonds in one molecule, and monomers having one or more C=C bonds and one or more polymerizable functional groups such as epoxy groups, aziridine groups, oxazoline groups, hydrazine groups, or methylol groups in one molecule. Preferably, a polyfunctional monomer is a monomer having two or more C=C bonds in one molecule.

[0100] Examples of polyfunctional monomers include (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, 1,2-ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and 1,9-nonanediol diacrylate (N Polyfunctional acrylates such as DDA, 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate (ester compounds of polyhydric alcohols and (meth)acrylic acid, etc.); allyl(meth)acrylate, vinyl(meth)acrylate, divinylbenzene, epoxyacrylate, polyester acrylate, urethane acrylate, butyldi(meth)acrylate, and hexyldi(meth)acrylate. The polyfunctional monomer is preferably a polyfunctional acrylate, and more preferably trimethylolpropane tri(meth)acrylate, hexanediol di(meth)acrylate, and dipentaerythritol hexa(meth)acrylate.

[0101] ≪1-3. Polarizing Film≫ As described above, a polarizing film typically includes a polarizer and a first protective film and a second protective film positioned on both sides of the polarizer.

[0102] <1-3-1. Polarizers> Polarizers are typically composed of a film made of a polyvinyl alcohol (PVA) resin containing a dichroic substance (e.g., iodine). Examples of PVA resins include polyvinyl alcohol, partially formalized polyvinyl alcohol, ethylene-vinyl alcohol copolymer, and partially saponified ethylene-vinyl acetate copolymer.

[0103] The PVA resin preferably includes an acetoacetyl-modified PVA resin. The amount of acetoacetyl-modified PVA resin included is, for example, 5% to 20% by weight, and may be 8% to 12% by weight, when the total PVA resin is considered to be 100% by weight.

[0104] The polarizer preferably contains iodide or sodium chloride (sometimes collectively referred to as halide). Examples of iodide include potassium iodide, sodium iodide, and lithium iodide. The halide content in the polarizer is preferably 5 to 20 parts by weight, and more preferably 10 to 15 parts by weight, per 100 parts by weight of PVA resin. In the manufacturing method described later, the halide can be incorporated into the coating solution that forms the PVA resin layer, which is a precursor of the polarizer, and finally introduced into the polarizer. By introducing a halide into the polarizer, the orientation of PVA molecules in the polarizer can be increased, making it possible to realize a polarizer with excellent optical properties (typically, a combination of high polarization degree and high single-element transmittance).

[0105] The polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. The transmittance of the polarizer alone is, for example, 41.0% to 46.0%, and may be 42.0% to 45.0%. The degree of polarization of the polarizer is, for example, 97.0% or higher, and may be 99.0% or higher, and may be 99.9% or higher.

[0106] The thickness of the polarizer is, for example, 12 μm or less, may be 10 μm or less, 1 μm to 8 μm, or 3 μm to 7 μm. By combining such a thin polarizer with a liquid crystal alignment solidification layer, a significant reduction in the thickness of the optical laminate becomes possible.

[0107] Polarizers can be manufactured by any suitable method. For example, the resin film forming the polarizer may be a single layer of resin film or a laminate of two or more layers.

[0108] Specific examples of polarizers composed of a single layer of resin film include hydrophilic polymer films such as PVA-based films, partially formalized PVA-based films, and partially saponified ethylene-vinyl acetate copolymer films that have been dyed with dichroic substances such as iodine or dichroic dyes and stretched, as well as polyene-based oriented films such as dehydrated PVA or dehydrochlorinated polyvinyl chloride. Preferably, polarizers obtained by dyeing a PVA-based film with iodine and uniaxially stretching it are used because they have excellent optical properties.

[0109] The above-mentioned iodine dyeing is carried out, for example, by immersing the PVA-based film in an iodine aqueous solution. The stretching ratio for the above-mentioned uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment, or during the dyeing process. Alternatively, dyeing may be performed after stretching. If necessary, the PVA-based film may be subjected to swelling treatment, crosslinking treatment, washing treatment, drying treatment, etc. For example, by immersing the PVA-based film in water and washing it before dyeing, not only can dirt and anti-blocking agents on the surface of the PVA-based film be washed away, but the PVA-based film can also be swollen to prevent uneven dyeing.

[0110] Specific examples of laminated polarizers include polarizers obtained using 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 coated on the resin substrate. A polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be produced, for example, by applying a PVA-based resin solution to a resin substrate, drying it to form a PVA-based resin layer on the resin substrate, and obtaining a laminate of the resin substrate and the PVA-based resin layer; or by stretching and dyeing the laminate to make the PVA-based resin layer a polarizer. Preferably, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is formed on one side of the resin substrate.

[0111] Stretching typically involves immersing the polarizer of the laminate in a boric acid aqueous solution for stretching. Furthermore, stretching may further include, if necessary, air-stretching the laminate at a high temperature (e.g., 95°C or higher) before stretching in the boric acid aqueous solution. Preferably, the laminate is subjected to a drying shrinkage treatment in which it shrinks by 2% or more in the width direction by heating while being transported in the longitudinal direction. Typically, this involves applying auxiliary air stretching, dyeing, water stretching, and drying shrinkage treatment to the laminate in this order. By introducing auxiliary stretching, it becomes possible to increase the crystallinity of PVA even when PVA is coated on a thermoplastic resin, making it possible to achieve high optical properties. At the same time, by increasing the orientation of PVA in advance, it is possible to prevent problems such as a decrease in the orientation of PVA or dissolution when immersed in water in the subsequent dyeing and stretching processes, making it possible to achieve high optical properties. Furthermore, when the PVA-based resin layer is immersed in a liquid, the disorder of the orientation of polyvinyl alcohol molecules and the decrease in orientation can be suppressed compared to when the PVA-based resin layer does not contain halides. As a result, the optical properties of the polarizer obtained through processing steps that involve immersing the laminate in a liquid, such as dyeing and underwater stretching, can be improved. Furthermore, the optical properties can be improved by shrinking the laminate in the width direction through a drying shrinkage treatment. The obtained resin substrate / polarizer laminate may be used as is (i.e., the resin substrate may also be used as a protective layer for the polarizer), or an appropriate protective layer may be laminated on the peeled surface obtained by removing the resin substrate from the resin substrate / polarizer laminate, or on the surface opposite to the peeled surface, depending on the purpose. Details of such polarizer manufacturing methods are described, for example, in Japanese Patent Application Publication No. 2012-73580 and Japanese Patent No. 6470455. The entire contents of these publications are incorporated herein by reference.

[0112] <1-3-2. Protective Film> The protective film that may be placed on both sides of the polarizer is typically composed of any suitable resin film. Typical materials that make up such a resin film include cellulosic resins such as triacetylcellulose (TAC), cycloolefin resins such as polynorbornene, (meth)acrylic resins, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin resins such as polyethylene, and polycarbonate resins. A typical example of a (meth)acrylic resin is a (meth)acrylic resin having a lactone ring structure. (Meth)acrylic resins having a lactone ring structure are described, for example, in Japanese Patent Publication No. 2000-230016, Japanese Patent Publication No. 2001-151814, Japanese Patent Publication No. 2002-120326, Japanese Patent Publication No. 2002-254544, and Japanese Patent Publication No. 2005-146084. These publications are incorporated herein by reference. Cellulose resins are preferred, and TAC is more preferred, from the viewpoint of ease of shaping. Cycloolefin resins and (meth)acrylic resins are preferred from the viewpoint of obtaining polarizing plates with low moisture permeability and excellent durability.

[0113] The protective film may be surface-treated as needed. Examples of surface treatments include hard coating, anti-reflective coating, anti-sticking coating, and anti-glare coating. The protective film may also be treated as needed to improve visibility when viewed through polarized sunglasses (typically by providing (elliptic) polarization functionality or providing ultra-high phase difference). By applying such treatments, excellent visibility can be achieved even when viewing the display screen through polarized lenses such as polarized sunglasses.

[0114] The protective film may be optically isotropic. For example, the in-plane phase difference Re(550) may be 0 nm to 10 nm, and the phase difference Rth(550) in the thickness direction may be -10 nm to +10 nm.

[0115] The thickness of the protective film is, for example, 10 μm to 80 μm, but may also be 12 μm to 40 μm, or 15 μm to 35 μm. If the protective film has a surface treatment, the thickness of the protective film includes the thickness of the surface treatment layer.

[0116] ≪1-4. Phase Difference Film≫ As described above, the phase difference film typically includes a first liquid crystal alignment solidification layer and a second liquid crystal alignment solidification layer. The optical laminate according to the embodiment of the present invention can be made thinner by using the liquid crystal alignment solidification layer in this way.

[0117] <1-4-1. Liquid Crystal Alignment Solidification Layer> A liquid crystal alignment solidification layer may be a layer in which liquid crystal compounds are aligned in a predetermined direction within the layer, and this alignment state is fixed.

[0118] Examples of liquid crystal compounds used in the liquid crystal alignment solidification layer include liquid crystal polymers and liquid crystal monomers. Preferably, the liquid crystal compound is a polymerizable liquid crystal compound, i.e., a liquid crystal monomer. If the liquid crystal compound is polymerizable, the orientation of the liquid crystal compound can be fixed by polymerizing it after orientation. The polymer formed by polymerization may be non-liquid crystal. Therefore, the formed liquid crystal alignment solidification layer does not undergo transitions to the liquid crystal phase, glass phase, or crystalline phase due to temperature changes, which are characteristic of liquid crystal compounds. As a result, the liquid crystal alignment solidification layer is unaffected by temperature changes and exhibits excellent stability.

[0119] In one embodiment, the liquid crystal alignment solidified layer can be formed using a liquid crystal composition containing a liquid crystal monomer. In this specification, a liquid crystal monomer contained in a liquid crystal composition means a compound having a polymerizable group and being liquid crystallinity. A polymerizable group means a group that participates in the polymerization reaction, and preferably a photopolymerizable group. Here, a photopolymerizable group means a group that can participate in the polymerization reaction by active radicals or acids generated from a photopolymerization initiator. As such a liquid crystal monomer, for example, polymerizable mesogenic compounds described in JP 2002-533742 (WO00 / 37585), EP358208 (US5211877), EP66137 (US4388453), WO93 / 22397, EP0261712, DE19504224, DE4408171, and GB2280445 can be used. Examples of such polymerizable mesogenic compounds include BASF's trade name LC242, Merck's trade name E7, and Wacker-Chem's trade name LC-Silicon-CC3767.

[0120] The mechanism by which the liquid crystalline properties of a liquid crystal monomer are manifested may be thermotropic or lyotropic. Furthermore, the liquid crystal phase may be composed of a nematic liquid crystal or a smectic liquid crystal. From the viewpoint of ease of manufacturing, a thermotropic nematic liquid crystal is preferred.

[0121] The temperature range in which liquid crystal monomers exhibit liquid crystalline properties varies depending on the type. Specifically, this temperature range is, for example, 40°C to 120°C, but may also be 50°C to 100°C or 60°C to 90°C.

[0122] The birefringence Δn of the liquid crystal alignment solidification layer is, for example, 0.06 or more, may be 0.08 or more, may be 0.09 or more, or may be 0.10 or more. The upper limit of Δn is, for example, 0.13 or less, and may be 0.12 or less. If Δn is within this range, the desired in-plane phase difference can be achieved with a very thin thickness. As a result, the liquid crystal alignment solidification layer and the optical laminate can be made even thinner, which can, for example, ultimately contribute to a significant reduction in the thinness of the image display device.

[0123] The liquid crystal alignment solidification layer may exhibit inverse dispersion wavelength characteristics in which the phase difference value increases with the wavelength of the measurement light, or it may exhibit positive wavelength dispersion characteristics in which the phase difference value decreases with the wavelength of the measurement light, or it may exhibit flat wavelength dispersion characteristics in which the phase difference value hardly changes with the wavelength of the measurement light.

[0124] The first liquid crystal alignment solidification layer and the second liquid crystal alignment solidification layer can typically function as a λ / 2 plate or a λ / 4 plate, respectively.

[0125] Specifically, Re(550) of the first liquid crystal alignment solidification layer is, for example, 150 nm to 300 nm, but may also be 200 nm to 270 nm, or 220 nm to 260 nm.

[0126] Specifically, Re(550) of the second liquid crystal alignment solidification layer is, for example, 100 nm to 200 nm, but may also be 110 nm to 160 nm, or 120 nm to 140 nm.

[0127] The thickness of at least one layer selected from the group consisting of a first liquid crystal alignment solidification layer and a second liquid crystal alignment solidification layer is, for example, 10 μm or less, and may be 8 μm or less, 5 μm or less, 4 μm or less, or even 3 μm or less. The lower limit of the thickness is, for example, 0.5 μm or more, and may be 1 μm or more. The thicknesses of the first liquid crystal alignment solidification layer and the second liquid crystal alignment solidification layer may be the same or different from each other.

[0128] The thickness of the first liquid crystal alignment solidification layer can typically be adjusted to obtain a desired in-plane phase difference of the λ / 2 plate. In one embodiment, the thickness of the first liquid crystal alignment solidification layer is, for example, 0.5 μm to 5.0 μm, but may also be 0.8 μm to 4.0 μm, 1.0 μm to 3.0 μm, 1.2 μm to 2.5 μm, or 1.3 μm to 2.0 μm. In another embodiment, the thickness of the first liquid crystal alignment solidification layer is, for example, 0.3 μm to 1.7 μm, but may also be 0.7 μm to 1.6 μm, 1.0 μm to 1.5 μm, or 1.3 μm to 1.5 μm.

[0129] The thickness of the second liquid crystal alignment solidification layer can typically be adjusted to obtain a desired in-plane phase difference for the λ / 4 plate. In one embodiment, the thickness of the second liquid crystal alignment solidification layer is, for example, 0.5 μm to 2.5 μm, but may also be 0.6 μm to 2.0 μm, 0.7 μm to 1.5 μm, 0.7 μm to 1.2 μm, or 0.7 μm to 1.1 μm.

[0130] The angle between the slow axis of the first liquid crystal alignment solidification layer and the transmission axis of the polarizer is, for example, 10° to 20°, but may also be 12° to 18° or 14° to 16°. The angle between the slow axis of the second liquid crystal alignment solidification layer and the transmission axis of the polarizer is, for example, 70° to 80°, but may also be 72° to 78° or 74° to 76°. The arrangement order of the first liquid crystal alignment solidification layer and the second liquid crystal alignment solidification layer may be reversed, and the angles between the slow axis of the first liquid crystal alignment solidification layer and the transmission axis of the polarizer and the angles between the slow axis of the second liquid crystal alignment solidification layer and the transmission axis of the polarizer may be reversed.

[0131] The average refractive index of the liquid crystal alignment solidification layer may vary depending on the composition forming the liquid crystal alignment solidification layer (essentially, the type of liquid crystal compound, the type, number, combination, and amount of additives). The average refractive index n1 of the first liquid crystal alignment solidification layer and the average refractive index n2 of the second liquid crystal alignment solidification layer may be the same or different (the average refractive index n1 of the first liquid crystal alignment solidification layer may be larger, and the average refractive index n2 of the second liquid crystal alignment solidification layer may be larger).

[0132] The average refractive index n1 of the first liquid crystal alignment solidification layer is, for example, 1.55 to 1.75, and may also be 1.60 to 1.70.

[0133] The average refractive index n2 of the second liquid crystal alignment solidification layer is, for example, 1.45 to 1.65, and may also be 1.50 to 1.60.

[0134] The average refractive index n1 of the first cured liquid crystal alignment layer and the average refractive index n2 of the second cured liquid crystal alignment layer may be reversed. The absolute value of the difference between the average refractive index n1 of the first cured liquid crystal alignment layer and the average refractive index n2 of the second cured liquid crystal alignment layer may be, for example, 0.00 to 0.20. Typically, the average refractive index of a cured liquid crystal alignment layer depends on the composition of the composition for forming the cured liquid crystal alignment layer in order to obtain desired optical properties.

[0135] A side-chain type thermotropic liquid crystal polymer may be introduced into the first cured liquid crystal alignment layer and / or the second cured liquid crystal alignment layer (substantially, the liquid crystal composition forming these layers). By introducing the side-chain type thermotropic liquid crystal polymer, an effect of homeotropic alignment (vertical alignment) of liquid crystal monomers can be achieved. As a result, nz of the first cured liquid crystal alignment layer and / or the second cured liquid crystal alignment layer can be increased, consequently the Nz coefficient of the first cured liquid crystal alignment layer and / or the second cured liquid crystal alignment layer can be appropriately adjusted, and finally, for example, the Nz coefficient of the retardation layer can be set in the range of 0.30 to 0.70 without providing a positive C plate.

[0136] Typical examples of the side-chain type thermotropic liquid crystal polymer include copolymers having a monomer unit containing a thermotropic liquid crystalline fragment side chain and a monomer unit containing a non-liquid crystalline fragment side chain. When the polymer has a thermotropic liquid crystalline fragment in a side chain, the side-chain type liquid crystal polymer can be aligned when a liquid crystal composition containing liquid crystal monomers is heated to a predetermined temperature. Further, when the side-chain type polymer has a non-liquid crystalline fragment in a side chain, the non-liquid crystalline fragment can interact with the photopolymerizable liquid crystal monomer, thereby producing an effect of causing homeotropic alignment of the photopolymerizable liquid crystal monomer.

[0137] As the side-chain type thermotropic liquid crystal polymer, a copolymer having a liquid crystalline monomer unit represented by general formula (I) and a non-liquid crystalline monomer unit represented by general formula (II) is preferably used.

[0138] In formula (I), R 1R is a hydrogen atom or a methyl group, 2 X is a cyano group, a fluoro group, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. 1 is -CO2- or -OCO-. a is an integer from 1 to 6, and b and c are independently 1 or 2.

[0139] In equation (II), R 3 R is a hydrogen atom or a methyl group, 4 This group is an alkyl group having 7 to 22 carbon atoms, a fluoroalkyl group having 1 to 22 carbon atoms, or a group represented by the following general formula (III).

[0140] In equation (III), R 5 is an alkyl group having 1 to 5 carbon atoms, and d is an integer from 1 to 6.

[0141] The ratio of liquid crystalline monomer units to non-liquid crystalline monomer units in side-chain liquid crystal monomers can be appropriately set depending on the purpose. The ratio (molar ratio) of non-liquid crystalline monomers to the total of liquid crystalline monomer units is, for example, 0.05 to 0.80, but may also be 0.10 to 0.60 or 0.15 to 0.50.

[0142] The ratio of liquid crystal monomer to side-chain liquid crystal polymer in the liquid crystal composition can be appropriately set depending on the purpose. The liquid crystal monomer content may be, for example, 1.2 to 20 times, 1.3 to 10 times, 1.4 to 9 times, or 1.5 to 8 times the content of the side-chain liquid crystal polymer.

[0143] A method for forming a side-chain type liquid crystal polymer and a liquid crystal alignment solidification layer is described, for example, in Japanese Patent No. 6769921, which may be incorporated herein by reference.

[0144] <1-4-2. Interlayer Bonding Agent> The first liquid crystal alignment solidification layer and the second liquid crystal alignment solidification layer may be laminated with an interlayer bonding agent (typically an adhesive). That is, the phase difference film may further include an adhesive layer located between the first liquid crystal alignment solidification layer and the second liquid crystal alignment solidification layer. However, the phase difference film may include an adhesive sheet instead of the adhesive layer.

[0145] As the adhesive layer that can be provided between the first liquid crystal alignment solidification layer and the second liquid crystal alignment solidification layer, any suitable adhesive layer can be used as long as it does not impair the effects of the present invention. Such an adhesive layer is usually adhered via an ultraviolet-curing adhesive or a water-based adhesive. Examples of water-based adhesives include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl latex-based adhesives, water-based polyurethanes, and water-based polyesters. In addition to the above, electron beam-curing adhesives can also be used as adhesive layers. The adhesive layer may contain a metal compound filler.

[0146] ≪1-5. Second Adhesive Sheet≫ The second adhesive sheet may be a known adhesive sheet that can be used in optical laminates or image display devices. The adhesive sheet described above in the description of the first adhesive sheet may be used as the second adhesive sheet. However, in this case, the configuration of the first adhesive sheet and the configuration of the second adhesive sheet may be the same or different.

[0147] The second adhesive sheet can typically be formed by curing an adhesive composition containing a base polymer. The base polymer in the adhesive composition may be a (meth)acrylic polymer. In this case, the second adhesive sheet becomes a (meth)acrylic adhesive sheet.

[0148] The base polymer is obtained by polymerization of monomer components. The monomer components preferably include alkyl (meth)acrylate. Specific examples of alkyl (meth)acrylate can be found in the explanation in section 1-2. First Adhesive Sheet.

[0149] The content of alkyl (meth)acrylate in the monomer component is, for example, 10% by weight or more, and may be 25% by weight or more, 50% by weight or more, 75% by weight or more, 80% by weight or more, 85% by weight or more, 90% by weight or more, and even 93% by weight or more. The above content is, for example, 99% by weight or less, 98% by weight or less, and even 95% by weight or less.

[0150] The monomer component may include monomers copolymerizable with alkyl (meth)acrylates (hereinafter sometimes referred to as "copolymer monomers"). Examples of copolymer monomers include hydroxyl group-containing monomers and carboxyl group-containing monomers. For specific examples of copolymer monomers and their content, refer to the explanation in section ≪1-2. First Adhesive Sheet≫.

[0151] The explanation in section 1-2. First Adhesive Sheet can also be applied to the method of forming the base polymer, other components that the adhesive composition may contain, and the method of manufacturing the second adhesive sheet.

[0152] The second adhesive sheet is preferably appropriately adjusted in terms of its thickness T2 and its storage modulus G2'(85°C). For example, the ratio G2'(85°C) / T2 of the storage modulus G2'(85°C) of the second adhesive sheet to its thickness T2 is preferably 1.0 kPa / μm or more, and may be 1.5 kPa / μm or more, 2.0 kPa / μm or more, 2.5 kPa / μm or more, 2.8 kPa / μm or more, 3.0 kPa / μm or more, 3.3 kPa / μm or more, 3.5 kPa / μm or more, 3.8 kPa / μm or more, and even 4.0 kPa / μm or more. The higher the ratio G2'(85°C) / T2, the more likely it is that the occurrence and elongation of cracks in the optical laminate when exposed to temperature changes will be suppressed. The upper limit of the ratio G2'(85°C) / T2 is, for example, 10.0 kPa / μm or less, and may also be 9.0 kPa / μm or less, 8.0 kPa / μm or less, 7.5 kPa / μm or less, and even 7.0 kPa / μm or less. The ratio G2'(85°C) / T2 may be between 1.0 kPa / μm and 10.0 kPa / μm, and may also be between 2.0 kPa / μm and 8.0 kPa / μm, and even between 4.0 kPa / μm and 7.0 kPa / μm.

[0153] The thickness T2 of the second adhesive sheet is, for example, 100 μm or less, and may be 80 μm or less, 50 μm or less, 40 μm or less, 30 μm or less, or even 20 μm or less. The lower limit of the thickness T2 is, for example, 1 μm or more, and may be 2 μm or more, 5 μm or more, or even 10 μm or more. The thickness T2 is preferably 5 μm to 30 μm, and more preferably 10 μm to 20 μm.

[0154] The storage modulus G2' (85°C) of the second adhesive sheet at 85°C is, for example, 200 kPa or less, and may be 150 kPa or less, 100 kPa or less, 90 kPa or less, and even 85 kPa or less. The storage modulus G2' (85°C) is, for example, 10 kPa or more, and may be 20 kPa or more, 30 kPa or more, 40 kPa or more, 50 kPa or more, 60 kPa or more, and even 70 kPa or more. The storage modulus G2' (85°C) is preferably 10 kPa to 200 kPa, and more preferably 50 kPa to 100 kPa.

[0155] The storage modulus G2' (25°C) of the second adhesive sheet at 25°C is not particularly limited and may be, for example, 50 kPa to 500 kPa, 60 kPa to 200 kPa, or even 70 kPa to 150 kPa.

[0156] The storage modulus G2' (25°C) and storage modulus G2' (85°C) mentioned above can be determined for the first adhesive sheet by the method described above.

[0157] ≪1-6. Shape of Optical Laminate≫ The shape of the optical laminate according to the embodiments of the present invention is not limited. The optical laminate can be distributed and stored, for example, as a wound body formed by winding a strip-shaped optical laminate, or as a single-wafer optical laminate.

[0158] The optical laminate may be rectangular or have an irregular shape. In optical laminates with irregular shapes, the application of stress due to temperature changes tends to be more complex compared to rectangular optical laminates, and the cracks described above tend to occur particularly in the irregularly shaped portions. In this embodiment, even when the optical laminate has an irregular shape, the occurrence and propagation of cracks tend to be suppressed.

[0159] In this specification, "rectangle" refers to the rectangle, which is the most common shape for a display surface in an image display device. Rectangles include squares. On the other hand, "irregular shape" refers to a shape other than a rectangle, and includes, for example, circles, ellipses, shapes that combine circles and / or ellipses, polygons other than rectangles, shapes that include curves on the outer perimeter, shapes with U-shaped, V-shaped, or irregular cutouts (sometimes called "notches") on the outer perimeter, shapes with depressions or through holes in the surface, and irregular shapes. Optical laminates with irregular shapes are often applied to image display devices in automotive meters, smartphones, smartwatches, and other portable information devices. Examples of optical laminates with irregular shapes are shown in Figures 2 to 8. Figures 2 to 8 show optical laminates with irregular shapes in a plan view. In Figures 2 to 8, reference numeral 1 denotes a notch, and reference numeral 2 denotes a through hole. Optical laminates with irregular shapes are not limited to those shown in Figures 2 to 8.

[0160] ≪1-7. Applications of Optical Laminates≫ Optical laminates according to embodiments of the present invention are typically used in image display devices. In other words, optical laminates may be used for image display devices. Image display devices include, for example, EL displays such as liquid crystal displays, organic EL displays, and inorganic EL displays. The applications of optical laminates are not limited to the above examples. Furthermore, image display devices that can use optical laminates are not limited to the above examples.

[0161] ≪≪2. Image Display Device≫≫ Figure 9 is a typical schematic cross-sectional view of an image display device according to an embodiment of the present invention. The image display device 200 in Figure 9 comprises an optical laminate 100, which further comprises, for example, an image forming layer 50 and a substrate 60. The optical laminate 100, the image forming layer 50 and the substrate 60 are stacked in this order, for example. The image forming layer 50 and the substrate 60 may have the same configuration as the image forming layer and substrate of known image display devices. Examples of the image forming layer 50 include an organic EL layer and a liquid crystal layer.

[0162] The image display device 200 may be an organic EL display or a liquid crystal display. However, the image display device 200 is not limited to the above examples. The image display device 200 may be an electroluminescent (EL) display, a plasma display (PD), a field emission display (FED), etc. The image display device 200 can be used for home appliance applications, automotive applications, public information display (PID) applications, etc.

[0163] The image display device according to the embodiment of the present invention can adopt any suitable configuration as long as it includes the optical laminate described in section 1. Optical Laminate, but typically the configuration is as shown in Figure 9 above.

[0164] The present invention will be specifically described below with reference to examples, but the present invention is not limited in any way to these examples. Where "parts" is mentioned, it means "parts by weight" unless otherwise specified, and where "%" is mentioned, it means "percent by weight" unless otherwise specified.

[0165] <Preparation of Phase Difference Film> [First Liquid Crystal Alignment Solidification Layer] A photopolymerizable liquid crystal compound exhibiting a nematic liquid crystal phase (BASF, "Paliocolor LC242") was dissolved in cyclopentanone to prepare a solution with a solid content of 30% by weight. A surfactant (BYK-361N, BIC Chemie Co., Ltd.) and a photopolymerization initiator (Omnirad907, IGM Resins) were added to this solution to prepare a liquid crystal composition solution. The amounts of surfactant and polymerization initiator added were 0.01 parts by weight and 3 parts by weight, respectively, per 100 parts by weight of the photopolymerizable liquid crystal compound. A biaxially oriented norbornene-based film (Zeonor Film, 33 μm thick, Re(550) = 135 nm, manufactured by Nippon Zeon Co., Ltd.) was prepared as the substrate. The above liquid crystal composition was applied to this substrate using a bar coater so that Re(550) was 240 nm, and the liquid crystal was oriented by heating at 100°C for 3 minutes. After cooling to room temperature, the substrate was exposed to a nitrogen atmosphere with an integrated light intensity of 400 mJ / cm². 2 The material was photocured by irradiation with ultraviolet light to obtain a laminate having a substrate / first liquid crystal alignment solidified layer configuration. The first liquid crystal alignment solidified layer was homogeneously oriented, with a thickness of 1.7 μm and an average refractive index of 1.590.

[0166] [Second Liquid Crystal Alignment Solidification Layer] A laminate having the configuration of substrate / second liquid crystal alignment solidification layer (Re(550) = 130 nm) was obtained in the same manner as the first liquid crystal alignment solidification layer, except that the coating thickness was changed. The second liquid crystal alignment solidification layer was homogeneously oriented, with a thickness of 0.92 μm and an average refractive index of 1.590.

[0167] [Adhesive Composition] Acryloylmorpholine (ACMO) (manufactured by KJ Chemicals, trade name "ACMO") 20 parts by weight, unsaturated fatty acid hydroxyalkyl ester modified epsilon-caprolactone (manufactured by Daicel Corporation, trade name "PLACCEL FA1DDM") 10 parts by weight, mixture of fluorene-based acrylate and reactive acrylate (manufactured by Osaka Gas Chemical Co., Ltd., trade name "Ogusol EA-F5710") 60 parts by weight, acrylic acid polymer (manufactured by Toagosei Co., Ltd., trade name "ARUFON UP-1190") 5 parts by weight, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one (manufactured by IGM Resins, trade name "Omnirad907") 3 parts by weight, 2,4-diethylthioxanthone (manufactured by Nippon Kayaku Co., Ltd., trade name "KAYACRE") Two parts by weight of DETX-S were mixed at 25°C for one hour to obtain an adhesive composition.

[0168] [Phase Difference Film] A first liquid crystal alignment solidified layer and a second liquid crystal alignment solidified layer were bonded together via an adhesive composition. Specifically, the adhesive composition was applied so that the total thickness of the adhesive was 1.0 μm, and the two liquid crystal alignment solidified layers were bonded together using a roll laminating machine. Subsequently, the adhesive composition was cured by irradiating it with UV light from the side of the second liquid crystal alignment solidified layer. This resulted in obtaining a phase difference film. The UV light irradiation was performed using an irradiation device equipped with a gallium-filled metal halide lamp (Fusion UV Systems, "Light HAMMER10", bulb: V-bulb) with a peak illuminance of 1600 mW / cm². 2 Total irradiation dose: 1000 / mJ / cm² 2 The experiment was conducted under conditions of wavelength 380–440 nm.

[0169] <Preparation of Polarizing Film> [Polarizer] A long, amorphous isophthalic copolymer polyethylene terephthalate film (thickness 100 μm) with a Tg of approximately 75°C was used as the thermoplastic resin substrate, and one side of the resin substrate was subjected to corona treatment. 100 parts by weight of a PVA-based resin, which was a mixture of polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosephymer") in a 9:1 ratio, was mixed with 13 parts by weight of potassium iodide, and this mixture was dissolved in water to prepare a PVA aqueous solution (coating solution). The above 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 with a thickness of 13 μm, thereby producing a laminate. The obtained laminate was uniaxially stretched 2.4 times in the longitudinal direction (longitudinal direction) in an oven at 130°C (air-assisted stretching treatment). Next, the laminate was immersed for 30 seconds in an insolubilization bath at a liquid temperature of 40°C (a boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) (insolubilization treatment). Next, it was immersed for 60 seconds in a staining bath at a liquid temperature of 30°C (a iodine aqueous solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with 100 parts by weight of water) while adjusting the concentration so that the final transmittance (Ts) of the polarizer obtained would be the desired value (staining treatment). Next, it was immersed for 30 seconds in a crosslinking bath at a liquid temperature of 40°C (a boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) (crosslinking treatment). Subsequently, the laminate was immersed in a boric acid aqueous solution (boric acid concentration 4% by weight, potassium iodide concentration 5% by weight) at a liquid temperature of 70°C and uniaxially stretched between rolls with different peripheral speeds to achieve a total stretch ratio of 5.5 times in the longitudinal direction (water stretching treatment). After that, the laminate was immersed in a washing bath at a liquid temperature of 20°C (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) (washing treatment). After that, while drying in an oven maintained at approximately 90°C, it was brought into contact with a heated roll made of stainless steel with a surface temperature maintained at approximately 75°C (drying shrinkage treatment). In this way, a polarizer with a thickness of approximately 5 μm was formed on the resin substrate, and a laminate having a resin substrate / polarizer configuration was obtained. The transmittance Ts of the polarizer alone was 43.3%.

[0170] [Polarizing Film] An HC-COP film was bonded to the surface of the polarizer (the side opposite to the resin substrate) via an ultraviolet-curing adhesive. The HC-COP film is a cycloolefin resin (COP) film (25 μm thick) with an HC layer (4 μm thick) formed on it, and it was bonded so that the COP film was on the polarizer side. The COP film had a Re(550) of 135 nm. Next, the resin substrate was peeled off, and a triacetylcellulose (TAC) film (25 μm thick) was bonded to the peeled surface via an ultraviolet-curing adhesive. In this way, a polarizing film having the structure of HC layer / COP film (protective film) / polarizer / TAC film (protective film) was obtained.

[0171] <Preparation of Adhesive Composition> [(Meth)acrylic Polymer P1] 88.5 parts by weight of phenoxybenzyl acrylate (POB-A), 1.5 parts by weight of 4-hydroxybutyl acrylate (4HBA), and 10.0 parts by weight of n-butyl acrylate (BA) were charged into a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and condenser. Furthermore, 0.1 parts by weight of 2,2'-azobisisobutyronitrile (AIBN) was added to 100 parts by weight of the monomer mixture as a polymerization initiator along with ethyl acetate. After introducing nitrogen gas and purging with nitrogen while gently stirring, the polymerization reaction was carried out for 7 hours while maintaining the liquid temperature in the flask at around 55°C. Subsequently, ethyl acetate was added to the resulting reaction solution to adjust the solid content concentration to 30% by weight to obtain a solution of (meth)acrylic polymer P1.

[0172] [Preparation of (meth)acrylic polymers P2 to P9] Solutions of (meth)acrylic polymers P2 to P9 were obtained in the same manner as for (meth)acrylic polymer P1, except that the type and amount of monomer were changed as shown in Table 1 below.

[0173] [Weight-average molecular weight of (meth)acrylic polymers] The weight-average molecular weight (Mw) of (meth)acrylic polymers P1 to P9 was evaluated by gel permeation chromatography (GPC) under the following conditions: • Analytical instrument: Waters, Acquity APC • Column: Tosoh, G7000HXL + GMHXL + GMHXL • Column temperature: 40°C • Eluent: Tetrahydrofuran (acid added) • Flow rate: 0.8 mL / min • Injection volume: 100 μL • Detector: Differential refractometer (RI) • Standard sample: Agilent, polystyrene (PS)

[0174]

[0175] The abbreviations in Table 1 are as follows: POB-A: Phenoxybenzyl acrylate 4HBA: 4-Hydroxybutyl acrylate 2HEA: 2-Hydroxyethyl acrylate AA: Acrylic acid ACMO: Acryloylmorpholine BA: n-Butyl acrylate

[0176] [Adhesive Composition A1] Adhesive composition A1 was obtained by blending 0.3 parts by weight of an isocyanate crosslinking agent (trimethylolpropane / xylylene diisocyanate trimer adduct, manufactured by Mitsui Chemicals, trade name "Takenate D-110N") with 100 parts by weight of the solid content of the solution of the above (meth)acrylic polymer P1.

[0177] [Adhesive Compositions A2 to A9] Adhesive compositions A2 to A9 were obtained by the same method as adhesive composition A1, except that the types and amounts of (meth)acrylic polymer, crosslinking agent, and additives were changed as shown in Table 2.

[0178]

[0179] The abbreviations in Table 2 are as follows: D110N: Trimethylolpropane / xylylene diisocyanate trimer adduct (manufactured by Mitsui Chemicals, trade name "Takenate D-110N") C / L: Trimethylolpropane / tolylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name "Coronate L") Peroxide: Benzoyl peroxide (manufactured by Nippon Oil & Fats Co., Ltd., Naiper BMT) KBM403: Silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM403")

[0180] (Example 1) First, adhesive composition A1 was applied to a release liner (Mitsubishi Chemical Corporation, MRF38-NS2) to create a coating film. A fountain coater was used to apply the adhesive composition A1. The coating film formed by the application was dried in an air-circulating constant-temperature oven at 120°C for 1 minute to produce a first adhesive sheet (thickness 5 μm).

[0181] A second adhesive sheet (thickness 30 μm) was prepared using the same method as the first adhesive sheet, except that adhesive composition A8 was used and the thickness of the coating film was changed.

[0182] Next, a polarizing film was bonded to the exposed surface of the first adhesive sheet to obtain a laminate having the configuration of polarizing film / first adhesive sheet / release liner. In this laminate, the first adhesive sheet was in contact with the TAC film contained in the polarizing film. Next, the release liner was peeled off from the first adhesive sheet, and a phase difference film was bonded to the exposed surface of the first adhesive sheet. This obtained a laminate having the configuration of polarizing film / first adhesive sheet / phase difference film. In this laminate, the first adhesive sheet was in contact with the first liquid crystal alignment solidification layer contained in the phase difference film. Next, the exposed surface of the second liquid crystal alignment solidification layer of the above laminate was plasma treated, and then this exposed surface was bonded to the exposed surface of the second adhesive sheet formed on the release liner to obtain a laminate having the configuration of polarized polarizing film / first adhesive sheet / phase difference film / second adhesive sheet / release liner.

[0183] A through-hole (a circle with a diameter of 2 mm in plan view) was created in the obtained laminate by end milling, passing through the laminate vertically, to obtain the optical laminate of Example 1 having an irregular shape. The size of this optical laminate was 160 mm in length and 80 mm in width, with one of the through-holes located near the center of the short side and at a distance of 2 mm from the short side. In addition, the absorption axis of the polarizing film in the optical laminate was 0° with respect to the long side.

[0184] (Examples 2-11 and Comparative Examples 1-4) Optical laminates of Examples 2-11 and Comparative Examples 1-4 were obtained by the same method as in Example 1, except that the type and thickness of the adhesive composition for producing the first and second adhesive sheets were changed as shown in Table 3.

[0185] <Evaluation> [Storage modulus of adhesive sheet] Dynamic viscoelasticity measurements were performed on the adhesive sheets used to fabricate the optical laminate described above under the measurement conditions described above. The "ARES-G2" manufactured by TA Instruments was used for the dynamic viscoelasticity measurements. From the results of the dynamic viscoelasticity measurements, the storage modulus G1' (25°C) at 25°C and the storage modulus G1' (85°C) at 85°C were determined for the first adhesive sheet. Similarly, the storage modulus G2' (25°C) at 25°C and the storage modulus G2' (85°C) at 85°C were determined for the second adhesive sheet.

[0186] Furthermore, based on the above results and the thickness T1 of the first adhesive sheet, the ratio of the storage modulus G1' (25°C) to the thickness T1, G1' (25°C) / T1, and the ratio of the storage modulus G1' (85°C) to the thickness T1, G1' (85°C) / T1, were calculated. Similarly, based on the thickness T2 of the second adhesive sheet, the ratio of the storage modulus G2' (85°C) to the thickness T2, G2' (85°C) / T2, was calculated. The relationship between the ratio G1' (25°C) / T1 and the ratio G1' (85°C) / T1 for the first adhesive sheet is shown in Figure 10.

[0187] [HC Test] The fabricated optical laminate was subjected to a heat cycle (HC) test using the following method. First, the optical laminate was fixed to the surface of a glass plate (Corning Eagle XG) using an acrylic adhesive sheet (25 μm thick) with a polarizing film as the bonding surface. Fixation was carried out in an atmosphere of 23°C and 50% RH. Next, the optical laminate, along with the glass plate, was placed in a heat cycle tester, and a 200-cycle HC test was performed under the following test conditions. After the test, the optical laminate was observed as a transmitted image using an optical microscope (10x magnification), and cracks were confirmed near the through-holes, which are irregular shapes, and the length of the largest crack was measured. ・HC test conditions Hold at -40°C for 30 minutes ⇒ Heat increase to 85°C and hold for 30 minutes ⇒ Cool down to -40°C. This is repeated 200 times as one cycle. However, the heating rate and cooling rate are set to 10°C / min.

[0188] [Durability Test] The fabricated optical laminate was subjected to a durability test using the following method. First, the release liner was peeled off, and the exposed second adhesive sheet was bonded to the surface of a glass plate (Corning Eagle XG) using a hand roller. The bonding was performed in an atmosphere of 23°C and 50% RH humidity. Next, it was treated in an autoclave at 50°C and 5 atmospheres (absolute pressure) for 15 minutes, and then left to cool to 23°C to stabilize the bond of the laminate to the glass plate. Next, the entire structure was left in a heated atmosphere of 85°C for 500 hours. After the period, it was returned to an atmosphere of 23°C and 50% RH humidity, and it was visually inspected to see if the laminate had peeled off from the glass plate. The high-temperature durability was evaluated according to the following criteria: A: No peeling observed. B: Peeling observed.

[0189]

[0190]

[0191] As can be seen from Tables 3 and 4, the optical laminate of the example, which had a first adhesive sheet with a ratio G1' (25°C) / T1 of 20.0 kPa / μm or higher and a ratio G1' (85°C) / T1 of 15.0 kPa / μm or lower, showed better HC test results compared to the comparative example. From these results, it can be said that the optical laminate of the example suppresses the occurrence and elongation of cracks when exposed to temperature changes.

[0192] The optical laminate of the present invention can be used in image display devices such as EL displays and liquid crystal displays.

Claims

1. An optical laminate comprising a polarizing film, a first adhesive sheet, and a phase difference film in this order, wherein the ratio of the storage modulus G1'(25°C) of the first adhesive sheet at 25°C to the thickness T1 of the first adhesive sheet, G1'(25°C) / T1, is 20.0 kPa / μm or more, and the ratio of the storage modulus G1'(85°C) of the first adhesive sheet at 85°C to the thickness T1, G1'(85°C) / T1, is 15.0 kPa / μm or less.

2. The optical laminate according to claim 1, wherein the ratio G1' (25°C) / T1 is 40.0 kPa / μm to 100.0 kPa / μm.

3. The optical laminate according to claim 1, wherein the ratio G1' (85°C) / T1 is 10.0 kPa / μm or less.

4. The optical laminate according to claim 1, wherein the thickness T1 is less than 10 μm.

5. The optical laminate according to claim 1, further comprising a second adhesive sheet located on the opposite side of the polarizing film from the phase difference film, wherein the ratio of the storage modulus G2'(85°C) of the second adhesive sheet at 85°C to the thickness T2 of the second adhesive sheet, G2'(85°C) / T2, is 2.0 kPa / μm or more.

6. The optical laminate according to claim 1, wherein the polarizing film includes a polarizer, and the thickness of the polarizer is 10 μm or less.

7. The optical laminate according to claim 6, wherein the polarizing film further includes a protective film.

8. The optical laminate according to claim 1, wherein the phase difference film includes a first liquid crystal alignment solidification layer and a second liquid crystal alignment solidification layer.

9. The optical laminate according to claim 8, wherein the thickness of at least one layer selected from the group consisting of the first liquid crystal alignment solidification layer and the second liquid crystal alignment solidification layer is 10 μm or less.

10. The optical laminate according to claim 1, wherein the first adhesive sheet comprises a crosslinked base polymer.

11. The optical laminate according to claim 10, wherein the base polymer is a (meth)acrylic polymer.

12. The optical laminate according to claim 10, wherein the monomer component constituting the base polymer includes an aromatic ring-containing monomer.

13. The optical laminate according to claim 12, wherein the aromatic ring-containing monomer comprises phenoxybenzyl acrylate.

14. The optical laminate according to claim 12, wherein the content of the aromatic ring-containing monomer in the monomer component is 80% by weight or more.

15. The optical laminate according to claim 1, having a shape other than a rectangle.

16. An image display device comprising an optical laminate according to any one of claims 1 to 15.

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