Optical laminate, optical laminate with polarizing film, image display device, and adhesive sheet

Abstract

This invention provides an optical laminate including a liquid crystal alignment fixing layer capable of suppressing the generation of linear non-uniformity and reducing depressions caused by localized loads. Furthermore, this invention provides an optical laminate with a polarizing film, comprising such an optical laminate and a polarizing film. Additionally, this invention provides an image display device including such an optical laminate. Furthermore, this invention provides an adhesive sheet preferably used for bonding the liquid crystal alignment fixing layer. The optical laminate of an embodiment of this invention sequentially comprises a first liquid crystal alignment fixing layer, an adhesive sheet, and a second liquid crystal alignment fixing layer. The thickness of the adhesive sheet is less than 20 μm. When the average refractive index of the adhesive sheet is set to n, the average refractive index of the first liquid crystal alignment fixing layer is set to n1, and the average refractive index of the second liquid crystal alignment fixing layer is set to n2, the largest average refractive index difference selected from the average refractive index difference calculated using |n-n1| and the average refractive index difference calculated using |n-n2| is less than 0.11. The indentation hardness of the adhesive sheet at 25°C is greater than 0.019 MPa.

Description

Technical Field

[0001] This invention relates to optical laminates, optical laminates with polarizing films, image display devices, and adhesive sheets. Background Technology

[0002] In recent years, image display devices, represented by liquid crystal display devices and electroluminescent (EL) display devices (e.g., organic EL display devices and inorganic EL display devices), have been rapidly gaining popularity.

[0003] Image display devices typically incorporate optical stacks that include a retardation layer. In recent years, the urgent need for thinner image display devices has increased, as has the need for thinner optical stacks containing retardation layers. Therefore, there is a demand for thinner retardation layers, which significantly contribute to the overall thickness.

[0004] As a thin retardation layer, an optical laminate formed by bonding two liquid crystal alignment fixing layers together using an interlayer adhesive is known. For example, a polarizer with a retardation layer has been reported (Patent Document 1), which sequentially comprises: a polarizer, a first retardation layer (typically a liquid crystal alignment fixing layer) and a second retardation layer (typically a liquid crystal alignment fixing layer), wherein the first retardation layer (typically a liquid crystal alignment fixing layer) and the second retardation layer (typically a liquid crystal alignment fixing layer) are bonded together via an adhesive layer. The laminate of the first retardation layer (typically a liquid crystal alignment fixing layer), the adhesive layer and the second retardation layer (typically a liquid crystal alignment fixing layer) in this polarizer with a retardation layer is equivalent to an optical laminate formed by bonding two liquid crystal alignment fixing layers together using an interlayer adhesive.

[0005] However, conventional image display devices containing optical laminates with liquid crystal alignment fixing layers are prone to linear non-uniformity (typically, a noticeable pink line can be observed along the absorption axis of the polarizer when viewed under a three-wavelength tube). Furthermore, conventional devices have also experienced issues with localized stress, such as indentations in the OCA caused by bonding pressure applied during the manufacturing of the image display device.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2019-204111 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] The objective of this invention is to provide an optical laminate including a liquid crystal alignment fixing layer that can suppress the generation of linear unevenness and reduce depressions caused by localized loads. Furthermore, it aims to provide an optical laminate with a polarizing film, comprising such an optical laminate and a polarizing film. Additionally, it aims to provide an image display device including such an optical laminate. Furthermore, it aims to provide an adhesive sheet, preferably for bonding the liquid crystal alignment fixing layer.

[0011] Methods for solving problems

[0012] [1] The optical laminate of the embodiments of the present invention sequentially comprises: a first liquid crystal alignment fixing layer, an adhesive sheet, and a second liquid crystal alignment fixing layer.

[0013] The thickness of the adhesive sheet is less than 20 μm.

[0014] When the average refractive index of the adhesive sheet is set to n, the average refractive index of the first liquid crystal alignment fixing layer is set to n1, and the average refractive index of the second liquid crystal alignment fixing layer is set to n2, the largest average refractive index difference selected from the average refractive index difference calculated using |n-n1| and the average refractive index difference calculated using |n-n2| is less than 0.11.

[0015] The adhesive sheet has an indentation hardness greater than 0.019 MPa at 25°C.

[0016] [2] In the optical laminate described in [1] above, the adhesive sheet may be composed of an acrylic adhesive formed from an acrylic adhesive composition comprising an acrylic polymer obtained by polymerizing monomer components.

[0017] [3] In the optical laminate described in [2] above, the Tg of the acrylic polymer can be lower than 13°C.

[0018] [4] In any one of the optical laminates described in [1] to [3] above, the indentation hardness may be less than 0.157 MPa.

[0019] [5] In any of the optical laminates described in [1] to [4] above, the thickness of the adhesive sheet may be 4 μm or more.

[0020] [6] In any one of the optical laminates described in [1] to [5] above, the average refractive index n of the adhesive sheet may be 1.52 or higher.

[0021] [7] In any of the optical laminates described in [1] to [6] above, a polarizing film may be provided on at least one side selected from the first liquid crystal alignment fixing layer side and the second liquid crystal alignment fixing layer side as viewed from the adhesive sheet.

[0022] [8] The optical laminate with polarizing film of the embodiment of the present invention has a polarizing film on the first liquid crystal alignment fixing layer side as viewed from the adhesive sheet of the optical laminate described in any one of [1] to [6].

[0023] [9] The optical laminate with polarizing film of the embodiment of the present invention has a polarizing film on the side of the second liquid crystal alignment fixing layer as viewed from the adhesive sheet of the optical laminate described in any one of [1] to [6].

[0024]

[10] The image display device according to the embodiments of the present invention includes the optical laminate described in any one of [1] to [7] above.

[0025]

[11] The adhesive sheet of the embodiment of the present invention has a thickness of less than 20 μm, an average refractive index n of 1.50 or more, and an indentation hardness of more than 0.019 MPa at 25°C.

[0026]

[12] The adhesive sheet described above in

[11] may be made of an acrylic adhesive, which is formed from an acrylic adhesive composition comprising an acrylic polymer obtained by polymerizing monomer components.

[0027]

[13] In the adhesive sheet described in

[12] above, the Tg of the acrylic polymer can be lower than 13°C.

[0028]

[14] In any of the adhesive sheets described in

[11] to

[13] above, the indentation hardness may be less than 0.157 MPa.

[0029]

[15] In any of the adhesive sheets described in

[11] to

[14] above, the average refractive index n may be 1.54 or higher.

[0030]

[16] The adhesive sheet described in any one of

[11] to

[15] above can be used for bonding liquid crystal alignment fixing layers.

[0031] The effects of the invention

[0032] According to embodiments of the present invention, an optical laminate including a liquid crystal alignment fixing layer can be provided, which can suppress the generation of linear non-uniformity and reduce depressions caused by localized loads. Additionally, an optical laminate with a polarizing film, comprising such an optical laminate and a polarizing film, can be provided. Furthermore, an image display device including such an optical laminate can be provided. Furthermore, an adhesive sheet preferably used for bonding the liquid crystal alignment fixing layer can be provided. Attached Figure Description

[0033] Figure 1 This is a cross-sectional schematic diagram of an optical laminate according to one embodiment of the present invention.

[0034] Figure 2 This is a cross-sectional schematic diagram of an optical laminate with a polarizing film according to one embodiment of the present invention.

[0035] Figure 3 This is a cross-sectional schematic diagram showing an embodiment of an optical laminate with a polarizing film in which an adhesive layer is provided on the side opposite to the adhesive sheet of the second liquid crystal alignment fixing layer. Detailed Implementation

[0036] [Regarding terminology]

[0037] In this specification, the term "weight" can be replaced with "mass," which is the SI unit conventionally used to express weight. The reverse is also true.

[0038] In this specification, when referred to as "(meth)acrylic acid", it means "acrylic acid and / or methacrylic acid"; when referred to as "(meth)acrylate", it means "acrylate and / or methacrylate"; when referred to as "(meth)allyl", it means "allyl and / or methylallyl"; and when referred to as "(meth)acrylaldehyde", it means "acrylaldehyde and / or methacrolein".

[0039] In this specification, the term "liquid crystal alignment layer" is used to refer to either the first liquid crystal alignment layer or the second liquid crystal alignment layer.

[0040] In this specification, regarding refractive indices (nx, ny, nz), "nx" is the refractive index in the direction where the refractive index reaches its maximum (i.e., the slow axis direction), "ny" is the refractive index in the direction orthogonal to the slow axis (i.e., the fast axis direction), and "nz" is the refractive index in the thickness direction. In this specification, nx, ny, and nz are values ​​relative to a wavelength of 550 nm. In this specification, the average refractive index is calculated as (nx + ny + nz) / 3.

[0041] In this specification, regarding the in-plane phase difference (Re), "Re(λ)" refers to the in-plane phase difference of the film measured using light with a wavelength of λnm at 23°C. For example, "Re(550)" refers to the in-plane phase difference of the film measured using light with a wavelength of 550nm at 23°C. When the thickness of the film is set to d (nm), Re(λ) can be obtained using the formula: Re=(nx-ny)×d.

[0042] In this specification, regarding the phase difference (Rth) in the thickness direction, "Rth(λ)" refers to the phase difference in the thickness direction of the film measured using light with a wavelength of λnm at 23°C. For example, "Rth(550)" refers to the phase difference in the thickness direction of the film measured using light with a wavelength of 550nm at 23°C. When the thickness of the film is set to d (nm), Rth(λ) can be obtained using the formula: Rth=(nx-nz)×d.

[0043] In this specification, the "Nz coefficient" can be obtained by Nz=Rth / Re.

[0044] 《1. Optical Laminates》

[0045] The optical laminate of an embodiment of the present invention sequentially comprises a first liquid crystal alignment fixing layer, an adhesive sheet, and a second liquid crystal alignment fixing layer. If the optical laminate of an embodiment of the present invention sequentially comprises a first liquid crystal alignment fixing layer, an adhesive sheet, and a second liquid crystal alignment fixing layer, any suitable other components may be included without impairing the effects of the present invention. Examples of such other components include, for example, the substrate used in forming the first liquid crystal alignment fixing layer and the second liquid crystal alignment fixing layer, and a release liner. In a preferred embodiment of the present invention, the first liquid crystal alignment fixing layer and the second liquid crystal alignment fixing layer constitute the outermost layer.

[0046] In addition to the first liquid crystal alignment fixing layer, the adhesive sheet, and the second liquid crystal alignment fixing layer, the optical laminate of the embodiments of the present invention may further include a positive C-plate. The positive C-plate exhibits the refractive index characteristic nz>nx=ny. The phase difference Rth(550) in the thickness direction of the positive C-plate is preferably -20nm to -300nm, more preferably -30nm to -250nm, even more preferably -40nm to -200nm, and particularly preferably -50nm to -150nm. Here, "nx=ny" includes not only the case where nx and ny are strictly equal, but also the case where nx and ny are substantially equal. That is, the in-plane phase difference Re(550) of the positive C-plate can be less than 10nm.

[0047] The positive C-plate can be formed, for example, using a liquid crystal composition comprising a side-chain type liquid crystal polymer described later. As a method for forming the positive C-plate, the method described in paragraphs

[0020] to

[0028] of Japanese Patent Application Publication No. 2002-333642 can be cited as an example. In this case, the thickness of the positive C-plate is preferably 0.5 μm to 10 μm, more preferably 0.5 μm to 8 μm, and even more preferably 0.5 μm to 5 μm.

[0048] Figure 1 This is a cross-sectional schematic diagram of an optical laminate according to one embodiment of the present invention. Figure 1The optical laminate 100 shown has a first liquid crystal alignment fixing layer 11, an adhesive sheet 20 and a second liquid crystal alignment fixing layer 12 in sequence. The first liquid crystal alignment fixing layer 11 and the adhesive sheet 20 are directly laminated together, and the adhesive sheet 20 and the second liquid crystal alignment fixing layer 12 are directly laminated together.

[0049] The optical laminate of the present invention can be used by providing a polarizing film on at least one side selected from the first liquid crystal alignment fixing layer side and the second liquid crystal alignment fixing layer side as viewed from the adhesive sheet. That is, the optical laminate of the present invention can be an optical laminate for laminating a polarizing film, and is used by providing a polarizing film on at least one side selected from the first liquid crystal alignment fixing layer side and the second liquid crystal alignment fixing layer side as viewed from the adhesive sheet. As such an embodiment, for example, as described below... Figure 2 The diagram shows an embodiment in which the polarizing film 200 is laminated onto the optical laminate 100 via an adhesive layer 30. It should be noted that... Figure 2 An embodiment is shown in which the polarizing film 200 is disposed on the side of the first liquid crystal alignment fixing layer 11 as viewed from the adhesive sheet 20 in the optical laminate 100, but the polarizing film 200 may also be disposed on the side of the second liquid crystal alignment fixing layer 12 as viewed from the adhesive sheet 20 in the optical laminate 100.

[0050] Without compromising the effectiveness of the invention, the total thickness of the optical laminate in the embodiments of the invention can be any suitable total thickness. Such a total thickness is preferably 20 μm or less, more preferably 1 μm to 20 μm, even more preferably 2 μm to 15 μm, and particularly preferably 3 μm to 10 μm.

[0051] In the optical laminate of the embodiments of the present invention, typically, the thickness of the adhesive sheet is less than 20 μm, and can be 17 μm or less, 15 μm or less, 13 μm or less, or 10 μm or less. In the optical laminate of the embodiments of the present invention, typically, the lower limit of the thickness of the adhesive sheet is 1 μm or more, and can be 2 μm or more, 3 μm or more, or 4 μm or more. In the optical laminate of the embodiments of the present invention, the thickness of the adhesive sheet is preferably 1 μm to 20 μm, more preferably 2 μm to 17 μm, further preferably 3 μm to 15 μm, and particularly preferably 4 μm to 13 μm. By adjusting the thickness of the adhesive sheet to the above ranges, the effects of the present invention can be further demonstrated. If the thickness of the adhesive sheet is too large, there is a risk that the effects of the present invention cannot be demonstrated, and in particular, there is a risk that depressions may occur due to localized load.

[0052] In the optical laminate of the embodiments of the present invention, when the average refractive index of the adhesive sheet is set to n, the average refractive index of the first liquid crystal alignment fixing layer is set to n1, and the average refractive index of the second liquid crystal alignment fixing layer is set to n2, typically, the largest average refractive index difference selected from the average refractive index difference calculated with |n-n1| and the average refractive index difference calculated with |n-n2| (i.e., the value of |n-n1| when |n-n1|>|n-n2|, the value of |n-n2| when |n-n1|<|n-n2|, and the values ​​of both |n-n1| and |n-n2| when |n-n1|=|n-n2|) is less than 0.11, preferably 0.10 or less, more preferably 0.09 or less, further preferably 0.07 or less, particularly preferably 0.06 or less, and most preferably 0.05 or less. The smaller the lower limit of the above-mentioned largest average refractive index difference, the more preferred, and preferably 0 or more. By adjusting the maximum average refractive index difference to the aforementioned range, the effects of the present invention can be further demonstrated, particularly by effectively suppressing the generation of linear inhomogeneities. If the maximum average refractive index difference is too large, there is a risk that the effects of the present invention will not be demonstrated, particularly the risk of generating linear inhomogeneities. It should be noted that |n-n1| represents the absolute value of n-n1, and |n-n2| represents the absolute value of n-n2.

[0053] In the optical laminate of the embodiments of the present invention, the indentation hardness of the adhesive sheet at 25°C is typically greater than 0.019 MPa, preferably greater than 0.019 MPa and less than 0.157 MPa, more preferably 0.020 MPa to 0.130 MPa, further preferably 0.030 MPa to 0.100 MPa, particularly preferably 0.040 MPa to 0.090 MPa, and most preferably 0.045 MPa to 0.080 MPa. By adjusting the indentation hardness to the above range, the effects of the present invention can be further demonstrated, especially by effectively reducing indentations caused by localized loads. If the indentation hardness is too low, the adhesive sheet may become too soft, posing a risk of indentations caused by localized loads. On the other hand, if the indentation hardness is too high, the adhesive sheet may become too hard, posing a risk of decreased adhesion between the adhesive sheet and the liquid crystal alignment fixing layer.

[0054] An optical laminate according to one embodiment of the present invention is an optical laminate comprising a first liquid crystal alignment fixing layer, an adhesive sheet, and a second liquid crystal alignment fixing layer in sequence. The effects of the present invention can be manifested by: (i) adjusting the thickness of the adhesive sheet to less than 20 μm; (ii) when the average refractive index of the adhesive sheet is set to n, the average refractive index of the first liquid crystal alignment fixing layer is set to n1, and the average refractive index of the second liquid crystal alignment fixing layer is set to n2, adjusting the largest average refractive index difference selected from the average refractive index difference calculated by |n-n1| and the average refractive index difference calculated by |n-n2| to less than 0.11; (iii) adjusting the adhesive sheet to have an indentation hardness greater than 0.019 MPa at 25°C. In the optical laminate of the above embodiment, the first liquid crystal alignment fixing layer and the second liquid crystal alignment fixing layer can be any suitable liquid crystal alignment fixing layer without impairing the effects of the present invention. Representative embodiments will be described in the following section "1-1. Liquid Crystal Alignment Fixing Layer". Furthermore, in the optical laminate of the above embodiments, any suitable adhesive sheet may be used without impairing the effect of the present invention. For representative embodiments, the following section "1-2. Adhesive Sheet" will be described.

[0055] 1-1. Liquid Crystal Alignment Fixing Layer

[0056] The optical laminate of the embodiments of the present invention includes a first liquid crystal alignment fixing layer and a second liquid crystal alignment fixing layer. The optical laminate of the embodiments of the present invention can be made thinner by using the liquid crystal alignment fixing layer in this way.

[0057] It should be noted that the liquid crystal alignment fixing layer can be a layer in which the liquid crystal compound is oriented in a given direction and its orientation state is fixed.

[0058] Examples of liquid crystal compounds used in liquid crystal alignment fixing layers include liquid crystal polymers and liquid crystal monomers. The liquid crystal compound is preferably a polymerizable liquid crystal compound, i.e., a liquid crystal monomer. If the liquid crystal compound is polymerizable, its alignment state can be fixed by polymerization after alignment. The polymer formed by polymerization can be non-liquid crystal. Therefore, the formed liquid crystal alignment fixing layer does not undergo the temperature-induced phase transitions characteristic of liquid crystal compounds, such as those to liquid crystal phases, glass phases, or crystalline phases. As a result, the liquid crystal alignment fixing layer is unaffected by temperature changes and exhibits extremely excellent stability.

[0059] In one embodiment of the liquid crystal alignment fixing layer, it can be formed using a liquid crystal composition containing liquid crystal monomers. In this specification, the liquid crystal monomers included in the liquid crystal composition refer to compounds having polymerizable groups and liquid crystal properties. Polymerizable groups refer to groups that participate in polymerization reactions, preferably photopolymerizable groups. Here, photopolymerizable groups refer to groups that can participate in polymerization reactions through active free radicals, acids, etc., generated by a photopolymerization initiator. As such liquid crystal monomers, polymerizable mesocrystalline compounds described, for example, in Japanese Patent Application Publication No. 2002-533742 (WO00 / 37585), EP358208 (US5211877), EP66137 (US4388453), WO93 / 22397, EP0261712, DE19504224, DE4408171, and GB2280445 can be used. Examples of such polymeric mesocrystalline compounds include BASF's LC242, Merck's E7, and Wacker-Chem's LC-Sillicon-CC3767.

[0060] The liquid crystal properties of a liquid crystal monomer can be exhibited by either thermal or lyotropic mechanisms. Furthermore, the liquid crystal phase can be either nematic or smectic. From the viewpoint of ease of manufacture, thermally induced nematic liquid crystals are preferred.

[0061] The temperature range in which liquid crystal monomers exhibit liquid crystal properties varies depending on the type. Specifically, such a temperature range is preferably 40°C to 120°C, more preferably 50°C to 100°C, and even more preferably 60°C to 90°C.

[0062] The birefringence Δn of the liquid crystal alignment fixing layer is preferably 0.06 or more, more preferably 0.08 or more, even more preferably 0.09 or more, and particularly preferably 0.10 or more. The upper limit of Δn can be, for example, 0.13, and also, for example, 0.12. If Δn is within such a range, the desired in-plane phase difference can be achieved with a very thin thickness. As a result, the liquid crystal alignment fixing layer and the optical laminate can be further thinned, ultimately contributing to a significant reduction in the thinness of the image display device.

[0063] For liquid crystal alignment fixing layers, it is possible to exhibit reverse wavelength dispersion characteristics where the phase difference increases with the wavelength of the measurement light, positive wavelength dispersion characteristics where the phase difference decreases with the wavelength of the measurement light, and flat wavelength dispersion characteristics where the phase difference does not change with the wavelength of the measurement light.

[0064] Typically, the first liquid crystal alignment fixing layer and the second liquid crystal alignment fixing layer can function as a λ / 2 plate or a λ / 4 plate, respectively. Typically, the first liquid crystal alignment fixing layer can function as a λ / 2 plate, and typically, the second liquid crystal alignment fixing layer can function as a λ / 4 plate.

[0065] Specifically, the Re(550) of the first liquid crystal alignment fixing layer is preferably 150nm~300nm, more preferably 200nm~270nm, and even more preferably 220nm~260nm.

[0066] Specifically, the Re(550) of the second liquid crystal alignment fixing layer is preferably 100nm~200nm, more preferably 110nm~160nm, and even more preferably 120nm~140nm.

[0067] Typically, the thickness of the first liquid crystal alignment fixing layer can be adjusted in a way that achieves the desired in-plane phase difference of the λ / 2 plate. In one embodiment, the thickness of the first liquid crystal alignment fixing layer is, for example, 0.5 μm to 5.0 μm, preferably 0.8 μm to 4.0 μm, more preferably 1.0 μm to 3.0 μm, further preferably 1.2 μm to 2.5 μm, and most preferably 1.3 μm to 2.0 μm. In another embodiment, the thickness of the first liquid crystal alignment fixing layer is preferably 0.3 μm to 1.7 μm, more preferably 0.7 μm to 1.6 μm, further preferably 1.0 μm to 1.5 μm, and particularly preferably 1.3 μm to 1.5 μm. Thus, according to embodiments of the present invention, the thickness of the first liquid crystal alignment fixing layer can be made thinner than before, and linear non-uniformity can be suppressed.

[0068] Typically, the thickness of the second liquid crystal alignment fixing layer can be adjusted in a way that yields the desired in-plane phase difference for a λ / 4 plate. In one embodiment, the thickness of the second liquid crystal alignment fixing layer is, for example, 0.5 μm to 2.5 μm, preferably 0.6 μm to 2.0 μm, more preferably 0.7 μm to 1.5 μm, further preferably 0.7 μm to 1.2 μm, and most preferably 0.7 μm to 1.1 μm.

[0069] The angle between the slow axis of the first liquid crystal alignment fixing layer and the transmission axis of the polarizer is preferably 10°~20°, more preferably 12°~18°, and even more preferably 14°~16°. The angle between the slow axis of the second liquid crystal alignment fixing layer and the transmission axis of the polarizer is preferably 70°~80°, more preferably 72°~78°, and even more preferably 74°~76°. It should be noted that the arrangement order of the first liquid crystal alignment fixing layer and the second liquid crystal alignment fixing layer can be reversed, and the angles between the slow axis of the first liquid crystal alignment fixing layer and the transmission axis of the polarizer and the angles between the slow axis of the second liquid crystal alignment fixing layer and the transmission axis of the polarizer can be reversed.

[0070] The average refractive index of the liquid crystal alignment fixing layer varies depending on the composition forming the liquid crystal alignment fixing layer (essentially the type of liquid crystal compound, the type, quantity, combination, and amount of additives, etc.). The average refractive index n1 of the first liquid crystal alignment fixing layer and the average refractive index n2 of the second liquid crystal alignment fixing layer can be the same or different (the average refractive index n1 of the first liquid crystal alignment fixing layer can be larger, or the average refractive index n2 of the second liquid crystal alignment fixing layer can be larger).

[0071] The average refractive index n1 of the first liquid crystal alignment fixing layer is preferably 1.55 to 1.75, more preferably 1.60 to 1.70.

[0072] The average refractive index n2 of the second liquid crystal alignment fixing layer is preferably 1.45 to 1.65, more preferably 1.50 to 1.60.

[0073] The average refractive index n1 of the first liquid crystal alignment fixing layer and the average refractive index n2 of the second liquid crystal alignment fixing layer can be opposite. The absolute value of the difference between the average refractive index n1 of the first liquid crystal alignment fixing layer and the average refractive index n2 of the second liquid crystal alignment fixing layer can, for example, be 0.00 to 0.20. Typically, the average refractive index of the liquid crystal alignment fixing layer depends on the composition of the composition in which the liquid crystal alignment fixing layer is formed to obtain the desired optical properties. As a result, in cases where linear non-uniformity may sometimes occur, according to embodiments of the present invention, such linear non-uniformity can be suppressed.

[0074] Side-chain thermotropic liquid crystal polymers can be introduced into the first and / or second liquid crystal alignment layers (essentially the liquid crystal composition forming them). By introducing the side-chain thermotropic liquid crystal polymers, an effect can be achieved that aligns the liquid crystal monomers vertically. As a result, the nz of the first and / or second liquid crystal alignment layers can be increased. Consequently, the Nz coefficient of the first and / or second liquid crystal alignment layers can be appropriately adjusted, ultimately, for example, setting the Nz coefficient of the phase retardation layer to a range of 0.30 to 0.70 without a positive C-plate.

[0075] Representative examples of side-chain thermotropic liquid crystal polymers include copolymers having monomer units containing thermotropic liquid crystallization segment side chains and monomer units containing non-liquid crystallization segment side chains. By incorporating thermotropic liquid crystallization segments in the side chains of the polymer, the side-chain type liquid crystal polymer will align when the liquid crystal composition containing liquid crystal monomers is heated to a given temperature. Furthermore, by incorporating non-liquid crystallization segments in the side chains of the side-chain type polymer, the interaction between the non-liquid crystallization segments and the photopolymerizable liquid crystal monomers can induce vertical orientation of the photopolymerizable liquid crystal monomers.

[0076] As a side-chain type thermotropic liquid crystal polymer, copolymers having liquid crystal monomer units represented by general formula (I) and non-liquid crystal monomer units represented by general formula (II) are preferred.

[0077] [Chemical Formula 1]

[0078]

[0079] [Chemical Formula 2]

[0080]

[0081] In equation (I), R 1 R is a hydrogen atom or a methyl group. 2 It is a cyano group, a fluorine group, an alkyl group with 1 to 6 carbon atoms, or an alkoxy group with 1 to 6 carbon atoms, X 1 It is either -CO2- or -OCO-, a is an integer from 1 to 6, and b and c are each independently 1 or 2.

[0082] In equation (II), R 3 For hydrogen atoms or methyl groups, R 4 It 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).

[0083] [Chemical Formula 3]

[0084]

[0085] In equation (III), R 5 It is an alkyl group with 1 to 5 carbon atoms, and d is an integer from 1 to 6.

[0086] The ratio of liquid crystal monomer units to non-liquid crystal monomer units in a side-chain type liquid crystal monomer can be appropriately set according to the purpose. The molar ratio (molar ratio) of non-liquid crystal monomers to the total of liquid crystal monomer units and non-liquid crystal monomer units is preferably 0.05 to 0.80, more preferably 0.10 to 0.60, and even more preferably 0.15 to 0.50.

[0087] The ratio of liquid crystal monomers to side-chain liquid crystal polymers in the liquid crystal composition can be appropriately set according to the purpose. The content of liquid crystal monomers is preferably 1.2 to 20 times that of side-chain liquid crystal polymers, more preferably 1.3 to 10 times, even more preferably 1.4 to 9 times, and particularly preferably 1.5 to 8 times.

[0088] Methods for forming side-chain liquid crystal polymers and liquid crystal alignment fixing layers are described, for example, in Japanese Patent No. 6769921, which may be referenced in this specification.

[0089] 1-2. Adhesive Sheets

[0090] The optical laminate of the present invention has an adhesive sheet between the first liquid crystal alignment fixing layer and the second liquid crystal alignment fixing layer.

[0091] The thickness of the adhesive sheet is as described above.

[0092] The average refractive index n of the adhesive sheet is, for example, 1.45 or more, preferably 1.50 or more, more preferably 1.52 or more, even more preferably 1.54 or more, particularly preferably 1.56 or more, and most preferably 1.57 or more. The upper limit of the average refractive index n of the adhesive sheet is preferably 1.70 or less.

[0093] The indentation hardness of the adhesive sheet at 25°C is as described above.

[0094] As an adhesive sheet, any suitable adhesive sheet can be used without impairing the effects of the present invention. Typically, the adhesive sheet is composed of an adhesive. Examples of such adhesives include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. From the viewpoint of further demonstrating the effects of the present invention, the adhesive sheet is preferably composed of an acrylic adhesive, which is formed from an acrylic adhesive composition comprising an acrylic polymer obtained by polymerizing monomer components. Sometimes, the main polymer component contained in such an acrylic polymer adhesive composition is referred to as the base polymer. The content of the base polymer contained in the adhesive composition is, for example, 50% by weight or more, 60% by weight or more, 70% by weight or more, 80% by weight or more, or 90% by weight or more. The upper limit of the content of the base polymer contained in the adhesive composition is, for example, 99.9% by weight or less, 99% by weight or less, or 95% by weight or less.

[0095] Without impairing the effects of the present invention, the adhesive sheet can be formed by any suitable method. For example, the adhesive sheet can be formed by drying a coating of adhesive composition disposed on a substrate. As a drying method, heating can be used, for example. As a substrate, a release film can be used, for example. As a release film, a known film that can be used when forming solvent-based adhesive sheets can be used. The adhesive sheet formed on the substrate can be transferred to other layers included in the optical laminate of embodiments of the present invention, such as a first liquid crystal alignment fixing layer and a second liquid crystal alignment fixing layer. The substrate can be other layers that may be included in the optical laminate of embodiments of the present invention.

[0096] Within the scope of not impairing the effects of the present invention, the drying temperature of the coating film can be any suitable drying temperature. Such a drying temperature may be, for example, below 130°C, below 125°C, below 120°C, below 110°C, or below 100°C. The drying temperature may be, for example, above 60°C, or above 80°C. Within the scope of not impairing the effects of the present invention, the drying time of the coating film can be any suitable drying time. Such a drying time may be, for example, 30 seconds to 300 seconds, 40 seconds to 240 seconds, or 60 seconds to 180 seconds.

[0097] In the optical laminate of the embodiments of the present invention, as the adhesive constituting the adhesive sheet, examples of adhesives that can be cited above include: acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. Hereinafter, as a representative embodiment, an adhesive sheet made of an acrylic adhesive will be described in detail, wherein the acrylic adhesive is formed from an acrylic adhesive composition containing an acrylic polymer.

[0098] <1-2-a. Acrylic polymers>

[0099] The acrylic polymer content in the acrylic adhesive composition is preferably 50% by weight or more, more preferably 70% by weight or more, and even more preferably 90% by weight or more, calculated as solids.

[0100] The acrylic polymer in an acrylic adhesive composition may be one type or two or more types.

[0101] For acrylic polymers, the Tg is preferably below 20°C, more preferably below 15°C, even more preferably below 13°C, further preferably above -15°C and below 13°C, even more preferably above -10°C and below 13°C, particularly preferably above -5°C and below 13°C, and most preferably above -3°C and below 13°C. By adjusting the Tg of the acrylic polymer to the above range, the effects of the present invention can be further demonstrated. If the Tg of the acrylic polymer is too high, the adhesive sheet will become too rigid, posing a risk of decreased adhesion between the adhesive sheet and the liquid crystal alignment fixing layer.

[0102] Acrylic polymers can be obtained by polymerizing monomer components. The monomer components preferably include aromatic ring monomers (m1).

[0103] The content of aromatic ring monomers (m1) in the monomer component is, for example, 30% by weight or more, 50% by weight or more, 60% by weight or more, 70% by weight or more, 75% by weight or more, 80% by weight or more, 85% by weight or more, 90% by weight or more, or 95% by weight or more. The upper limit of the content of aromatic ring monomers (m1) in the monomer component is, for example, 100% by weight, but can be 98% by weight or less, 96% by weight or less, 94% by weight or less, 92% by weight or less, 90% by weight or less, 85% by weight or less, or 75% by weight or less. From the viewpoint of further demonstrating the effects of the present invention, the content of aromatic ring monomers (m1) in the monomer component is preferably 50% by weight to 100% by weight, more preferably 60% by weight to 95% by weight, further preferably 65% ​​by weight to 90% by weight, and particularly preferably 67% by weight to 88% by weight.

[0104] As an aromatic ring monomer (m1), a compound containing at least one aromatic ring and at least one olefinic unsaturated group in one molecule can be used. The aromatic ring monomer (m1) can be only one type or two or more types.

[0105] Examples of olefinic unsaturated groups include (meth)acryloyl, vinyl, and (meth)allyl. From the viewpoint of further demonstrating the effects of the present invention, (meth)acryloyl and vinyl groups are preferred as olefinic unsaturated groups, more preferably (meth)acryloyl, and even more preferably acryloyl. Therefore, as preferred embodiments of the aromatic ring-containing monomer (m1), examples include (meth)acrylates containing aromatic rings and vinyl compounds containing aromatic rings.

[0106] From the viewpoint of being able to suppress the decrease in the softness of the adhesive, the aromatic ring monomer (m1) is preferably a compound containing one olefinic unsaturated group per molecule (i.e., a monofunctional monomer).

[0107] A single molecule of an aromatic ring monomer (m1) may contain one or more aromatic rings. There is no particular limit to the number of aromatic rings contained in an aromatic ring monomer (m1), for example, it may be less than 16, less than 12, less than 8, less than 6, less than 4, less than 3, or less than 2.

[0108] The aromatic ring contained in the aromatic ring monomer (m1) can be, for example, a benzene ring (which can be a benzene ring that forms part of a biphenyl structure or a fluorene structure); a hydrocarbon ring such as a condensed ring of a naphthalene ring, an indene ring, azulene ring, anthracene ring, or a phenanthrene ring; or it can be a pyridine ring, a pyrimidine ring, a pyridazine ring, a pyrazine ring, a triazine ring, a pyrrole ring, a pyrazole ring, an imidazole ring, or a triazole ring. azole ring, iso- Heterocyclic rings such as azole rings, thiazole rings, and thiophene rings. Examples of heteroatoms contained in such heterocyclic rings include nitrogen, sulfur, and oxygen, with nitrogen and sulfur being preferred. Aromatic ring monomers (m1) may, for example, have a structure formed by the condensation of one or more carbon rings and one or more heterocyclic rings, such as the dinaphthothiophene structure.

[0109] The aromatic ring contained in the aromatic ring monomer (m1) may have substituents on the ring-forming atoms. There may be only one substituent or two or more. Examples of substituents include: alkyl, alkoxy, aryloxy, hydroxy, halogen atom, hydroxyalkyl, hydroxyalkyloxy, and glycidyloxy.

[0110] The aromatic ring contained in the aromatic ring monomer (m1) can be directly bonded to the olefinic unsaturated group or bonded via a linking group. Such a linking group can be, for example, a group containing at least one structure selected from alkylene, oxoalkylene, poly(oxoalkylene), phenyl, alkylphenyl, alkoxyphenyl, where one or more hydrogen atoms of these groups are replaced by hydroxyl groups (e.g., hydroxyalkylene), oxy (-O-), or thioether (-S-). From the viewpoint of further demonstrating the effects of the invention, such a linking group is preferably a group containing at least one structure selected from alkylene, oxoalkylene, and poly(oxoalkylene). The number of carbon atoms in the alkylene and oxoalkylene groups is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 to 2. The number of repetitions of the oxoalkylene unit in the poly(oxoalkylene) group is preferably 2 to 3.

[0111] From the viewpoint of further demonstrating the effects of the present invention, the monomer (m1) may comprise a monomer having two or more aromatic rings in one molecule (hereinafter sometimes referred to as "monomer (m2) containing multiple aromatic rings"). Examples of monomers (m2) containing multiple aromatic rings include: monomers having a structure in which two or more non-fused aromatic rings are bonded together via a linking group; monomers having a structure in which two or more non-fused aromatic rings are directly chemically bonded together; monomers having a fused aromatic ring structure; monomers having a fluorene structure; monomers having a dinaphthothiophene structure; and monomers having a dibenzothiophene structure.

[0112] As one embodiment of the aromatic ring-containing monomer (m1), the content ratio of the monomer (m2) containing multiple aromatic rings in the aromatic ring-containing monomer (m1) can be, for example, 50% by weight or more, 70% by weight or more, 80% by weight or more, 85% by weight or more, 90% by weight or more, 95% by weight or more, or 98% by weight or more. The upper limit of the content ratio of the monomer (m2) containing multiple aromatic rings in the aromatic ring-containing monomer (m1) is 100% by weight. From the viewpoint of further demonstrating the effects of the present invention, the content ratio of the monomer (m2) containing multiple aromatic rings in the aromatic ring-containing monomer (m1) is preferably 80% by weight to 100% by weight, more preferably 85% by weight to 100% by weight, further preferably 90% by weight to 100% by weight, particularly preferably 95% by weight to 100% by weight, and most preferably 98% by weight to 100% by weight.

[0113] As another embodiment of the aromatic ring-containing monomer (m1), the proportion of the monomer (m2) containing multiple aromatic rings in the aromatic ring-containing monomer (m1) can be, for example, less than 50% by weight, less than 40% by weight, less than 30% by weight, less than 20% by weight, less than 10% by weight, or less than 5% by weight. In this embodiment, the aromatic ring-containing monomer (m1) preferably includes the monomer (m3) having one aromatic ring per molecule, as described later.

[0114] Linking groups that may be present in a monomer (m2) containing multiple aromatic rings include, for example: oxy group (-O-), thioether group (-S-), oxoalkylene group (-O-(CH2)). n - group, wherein n is 1 to 3, preferably 1), thionyl (-S-(CH2)) n - group, wherein n is 1 to 3, preferably 1), straight-chain alkylene (-(CH2) n -A group consisting of n, where n is 1 to 6, preferably 1 to 3), or an alkylene group, a alkylene group consisting of oxoalkylene, thioalkylene, or straight-chain alkylene, which is partially or completely halogenated.

[0115] Monomers having a structure consisting of two or more non-fused aromatic rings bonded together by a linking group include, for example, phenoxybenzyl (meth)acrylate (e.g., m-phenoxybenzyl (meth)acrylate), phenylthiobenzyl (meth)acrylate, and benzyl (meth)acrylate.

[0116] Monomers having a structure consisting of two or more non-fused aromatic rings directly chemically bonded together include, for example, (meth)acrylates containing a biphenyl structure, (meth)acrylates containing a terphenyl structure, and vinyl-containing biphenyls. Specific examples include o-phenylphenol methacrylate and methyl biphenyl methacrylate.

[0117] Examples of monomers having a fused aromatic ring structure include: (meth)acrylates containing a naphthyl ring, (meth)acrylates containing anthracene ring, vinyl naphthalene, and vinyl anthracene. Specific examples include: 1-naphthyl methyl (meth)acrylate (also known as 1-naphthyl methyl (meth)acrylate), hydroxyethylated β-naphthol acrylate, 2-naphthyl ethyl (meth)acrylate, 2-naphthoxyethyl acrylate, and 2-(4-methoxy-1-naphthoxy)ethyl (meth)acrylate.

[0118] Examples of monomers with a fluorene structure include 9,9-bis(4-hydroxyphenyl)fluorene(meth)acrylate and 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene(meth)acrylate. It should be noted that monomers with a fluorene structure comprise a structural moiety formed by the direct chemical bonding of two benzene rings, and therefore can be included in the concept of monomers with structures formed by the direct chemical bonding of two or more non-fused aromatic rings.

[0119] Examples of monomers having a dinaphthothiophene structure include: dinaphthothiophenes containing (meth)acryloyl groups, dinaphthothiophenes containing vinyl groups, and dinaphthothiophenes containing (meth)allyl groups. Specific examples include: (meth)acryloyloxymethyl dinaphthothiophene (for example, with CH2CH(R) bonded at the 5th or 6th position of the dinaphthothiophene ring). 1 Compounds with the structure )C(O)OCH2-, R 1 (Hydrogen atom or methyl group), (meth)acryloyloxyethyl dinaphthothiophene (for example, CH2CH(R) bonded at the 5 or 6 position of the dinaphthothiophene ring). 1 )C(O)OCH(CH3)- or CH2CH(R 1 Compounds with the structure )C(O)OCH2CH2-, R 1These include (a hydrogen atom or methyl group), vinyl dinaphthothiophene (e.g., compounds with a vinyl group bonded to the 5 or 6 position of the dinaphthothiophene ring), and (methyl)allyloxy dinaphthothiophene. It should be noted that monomers with a dinaphthothiophene structure can also be included in the concept of monomers with a fused aromatic ring structure because they contain a naphthalene structure and have a structure formed by the condensation of a thiophene ring with two naphthalene structures.

[0120] Examples of monomers with a dibenzothiophene structure include dibenzothiophene containing a (meth)acryloyl group and dibenzothiophene containing a vinyl group. It should be noted that monomers with a dibenzothiophene structure have a structure formed by the condensation of a thiophene ring and two benzene rings, and therefore can be included in the concept of monomers with fused aromatic ring structures. It should also be noted that neither dinaphthothiophene nor dibenzothiophene structures belong to structures formed by the direct chemical bonding of two or more non-fused aromatic rings.

[0121] As an aromatic ring monomer (m1), a monomer (m3) having one aromatic ring in one molecule can be used. A monomer (m3) having one aromatic ring in one molecule can, for example, help to improve the softness of the adhesive, adjust the adhesive properties, and improve the transparency.

[0122] Examples of monomers (m3) containing one aromatic ring per molecule include: benzyl (meth)acrylate, methoxybenzyl (meth)acrylate, phenyl (meth)acrylate, ethoxylated phenolic (meth)acrylate, phenoxypropyl (meth)acrylate, phenoxybutyl (meth)acrylate, cresol (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, and benzyl chloro(meth)acrylate, all containing a carbon-containing aromatic ring; 2-(4,6-dibromo-2-sec-butylphenoxy)ethyl (meth)acrylate, 2-(4,6-dibromo-2-sec-butylphenoxy)ethyl (meth)acrylate, etc. 2-Isopropylphenoxy)ethyl ester, 6-(4,6-dibromo-2-sec-butylphenoxy)hexyl acrylate, 6-(4,6-dibromo-2-isopropylphenoxy)hexyl acrylate, 2,6-dibromo-4-nonylphenyl acrylate, 2,6-dibromo-4-dodecylphenyl acrylate, and other (meth)acrylates containing bromine-substituted aromatic rings; vinyl compounds containing carbon aromatic rings such as styrene, α-methylstyrene, vinyltoluene, and tert-butylstyrene; N-vinylpyridine, N-vinylpyrimidine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazolium, and N-vinylpyrrolidone. Compounds such as azoles that have vinyl substituents on aromatic heterocycles.

[0123] As one embodiment of the aromatic ring monomer (m1), the proportion of monomer (m3) having one aromatic ring in one molecule of the aromatic ring monomer (m1) can be, for example, less than 50% by weight, less than 30% by weight, less than 20% by weight, less than 15% by weight, less than 10% by weight, less than 5% by weight, or less than 2% by weight. The lower limit of the proportion of monomer (m3) having one aromatic ring in one molecule of the aromatic ring monomer (m1) is 0% by weight.

[0124] In another embodiment of the aromatic ring-containing monomer (m1), the proportion of monomer (m3) having one aromatic ring in one molecule of the aromatic ring-containing monomer (m1) can be, for example, 50% by weight or more, 60% by weight or more, 70% by weight or more, 80% by weight or more, 90% by weight or more, or 95% by weight or more. In this embodiment, the aromatic ring-containing monomer (m1) may not contain monomer (m2) containing multiple aromatic rings.

[0125] From the viewpoint of further demonstrating the effects of the present invention, the following monomers (m1) containing aromatic rings are preferably specifically mentioned above: o-phenoxybenzyl acrylate, 1-naphthyl methyl acrylate, ethoxylated o-phenylphenol acrylate, benzyl acrylate, phenoxyethyl acrylate, phenoxydiethylene glycol acrylate, 6-acryloyloxymethyl dinaphthiophene, 6-methacryloyloxymethyl dinaphthiophene, 5-acryloyloxyethyl dinaphthiophene, 6-acryloyloxyethyl dinaphthiophene, 6-vinyl dinaphthiophene, and 5-vinyl dinaphthiophene.

[0126] The monomer component may include monomers capable of copolymerizing with aromatic ring monomers (m1) (hereinafter sometimes referred to as "comonomers (m4)"). Comonomers (m4) may be one or more. Examples of comonomers (m4) include: alkyl (meth)acrylates, hydroxyl-containing monomers, carboxyl-containing monomers, and amide-containing monomers.

[0127] The alkyl group in (meth)acrylates has, for example, 1 to 30 carbon atoms. The alkyl group can be linear, branched, or cyclic. Examples of alkyl groups include: methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, hexyl, cyclohexyl, heptyl, 2-ethylhexyl, isooctyl, nonyl, decyl, isodecyl, dodecyl, isomyristyl, lauryl, tridecyl, pentadecyl, hexadecyl, heptadecanyl, and octadecyl. Alkyl (meth)acrylates can be of only one type or two or more types. From the viewpoint of further demonstrating the effects of the present invention, butyl acrylate is preferably an example of an alkyl (meth)acrylate.

[0128] The content of alkyl (meth)acrylate in the monomer component can be, for example, less than 50% by weight, less than 40% by weight, less than 35% by weight, less than 30% by weight, less than 25% by weight, less than 22% by weight, less than 20% by weight, less than 17% by weight, less than 15% by weight, or less than 13% by weight. The lower limit of the content of alkyl (meth)acrylate in the monomer component is, for example, more than 1% by weight, more than 3% by weight, or more than 5% by weight. Alternatively, the monomer component may not contain alkyl (meth)acrylate.

[0129] Hydroxyl-containing monomers are compounds whose structures contain hydroxyl groups and polymerizable unsaturated double bonds such as (meth)acryloyl groups and vinyl groups. Hydroxyl-containing monomers can be hydroxyl-containing (meth)acrylates. Examples of hydroxyl-containing (meth)acrylates include: 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylaurate (meth)acrylate, and other alkyl hydroxy(meth)acrylates; and cycloalkyl hydroxy(meth)acrylates such as (4-hydroxymethylcyclohexyl)acrylate. Preferably, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred.

[0130] The proportion of hydroxyl-containing monomers in the monomer component can be, for example, 0.5% by weight or more, 1% by weight or more, or 1.5% by weight or more. The upper limit for the proportion of hydroxyl-containing monomers in the monomer component can be, for example, 10% by weight or less, 7% by weight or less, 5% by weight or less, 4.5% by weight or less, 4% by weight or less, 3.5% by weight or less, 3% by weight or less, or 2.5% by weight or less. Alternatively, the monomer component may not contain hydroxyl-containing monomers.

[0131] Carboxyl-containing monomers are compounds whose structures contain a carboxyl group and polymerizable unsaturated double bonds such as (meth)acryloyl groups and vinyl groups. Carboxyl-containing monomers can be carboxyl-containing (meth)acrylates. Examples of carboxyl-containing (meth)acrylates include: (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid.

[0132] The proportion of carboxyl-containing monomers in the monomer component can be, for example, less than 10% by weight, less than 7% by weight, less than 5% by weight, or less than 3% by weight. The lower limit of the proportion of carboxyl-containing monomers in the monomer component can be, for example, more than 0.5% by weight or more than 1% by weight. In addition, the monomer component may not contain carboxyl-containing monomers.

[0133] Amide monomers are compounds whose structures contain amide groups and polymerizable unsaturated double bonds such as (meth)acryloyl groups and vinyl groups. Amide monomers can be amide-containing (meth)acrylates. Examples of amide-containing (meth)acrylates include: (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N-isopropylacrylamide, N-methyl (meth)acrylamide, N-butyl (meth)acrylamide, N-hexyl (meth)acrylamide, N-hydroxymethyl (meth)acrylamide, N-hydroxymethyl-N-propane (meth)acrylamide, aminomethyl (meth)acrylamide, aminoethyl (meth)acrylamide, mercaptomethyl (meth)acrylamide, mercaptoethyl (meth)acrylamide, and other acrylamide monomers; N-(meth)acryloylmorpholine, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, and other N-acryloyl heterocyclic monomers; and N-vinylpyrrolidone, N-vinyl-ε-caprolactam, and other N-vinyl lactam monomers.

[0134] The proportion of amide-containing monomers in the monomer component can be, for example, less than 10% by weight, less than 7% by weight, less than 5% by weight, or less than 3% by weight. The lower limit of the proportion of amide-containing monomers in the monomer component can be, for example, more than 0.5% by weight or more than 1% by weight. In addition, the monomer component may not contain amide-containing monomers.

[0135] In addition to the above, other comonomers (m4) include, for example: maleic anhydride, itaconic anhydride, and other anhydride-containing monomers; caprolactone adducts of acrylic acid; allyl sulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamide propanesulfonic acid, sulfopropyl (meth)acrylate, and other sulfonic acid-containing monomers; 2-hydroxyethyl acryloyl phosphate, and other phosphate-containing monomers; aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, tert-butylaminoethyl (meth)acrylate, and other alkylaminoalkyl (meth)acrylates; methoxy (meth)acrylates... alkyl methacrylates such as ethoxyethyl methacrylate; succinic acid imide monomers such as N-(meth)acryloyloxymethylenesuccinate imide, N-(meth)acryloyl-6-oxohexamethylenesuccinate imide, and N-(meth)acryloyl-8-oxooctamethylenesuccinate imide; maleimide monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, and N-phenylmaleimide; and maleimide monomers such as N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, and N-2-ethylhexylitaconimide. Itaconitum monomers such as imides, N-cyclohexylitaconimide, and N-laurylitaconimide; vinyl monomers such as vinyl acetate and vinyl propionate; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; epoxy-containing (meth)acrylates such as glycidyl acrylate; diol (meth)acrylates such as carbitol (meth)acrylate, ethyl carbitol (meth)acrylate, polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate; tetrahydrofurfuryl (meth)acrylate. Fluorinated (meth)acrylates, organosilicon (meth)acrylates, etc.; silane monomers containing silicon atoms, such as 3-acryloyloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8-vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, 10-acryloyloxydecyltriethoxysilane, etc.

[0136] The proportion of other comonomers in the monomer component can be, for example, less than 5% by weight, less than 3% by weight, or less than 1% by weight. Alternatively, the monomer component may not contain any other comonomers.

[0137] Acrylic polymers can serve as the base polymers in acrylic adhesive compositions. Acrylic polymers can be formed through various known polymerization methods, including solution polymerization, radiation polymerization using electron beams, ultraviolet (UV) light, bulk polymerization, and emulsion polymerization. Typically, the polymerization is free radical polymerization. Acrylic polymers can be any of the following: random copolymers, block copolymers, graft copolymers, etc.

[0138] The polymerization solvent used in solution polymerization can be known polymerization solvents such as ethyl acetate and toluene. Solution polymerization can be carried out, for example, using a polymerization initiator and under a gas stream of inert gas such as nitrogen. The polymerization conditions can be any suitable conditions without impairing the effects of the present invention. Examples of such polymerization conditions include a polymerization temperature of 50°C to 70°C and a polymerization time of 5 hours to 30 hours.

[0139] As polymerization initiators, chain transfer agents, and emulsifiers that can be used in free radical polymerization, any suitable compound can be used without compromising the effects of the present invention.

[0140] Examples of azo initiators used in polymerization include: 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-amidinylpropane)dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane]dihydrochloride, 2,2'-azobis(2-methylpropanedisulfate), 2,2'-azobis(N,N'-dimethyleneisobutylamidine), 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropanedisulfate] hydrate (e.g., Wako Pure Chemical Industries, Ltd. VA-057), etc.; persulfates such as potassium persulfate and ammonium persulfate; and di(2-ethylhexyl) peroxide dicarbonate, etc. Peroxide initiators include di(4-tert-butylcyclohexyl) dicarbonate, disec-butyl percarbonate, tert-butyl peroxynedecanoate, tert-hexyl peroxynepentanoate, tert-butyl peroxynepentanoate, dilauroyl peroxide, dioctanoyl peroxide, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, di(4-methylbenzoyl) peroxide, dibenzoyl peroxide, tert-butyl peroxyisobutyrate, 1,1-di(tert-hexylperoxy)cyclohexane, tert-butyl hydroperoxide, and hydroperoxide. Redox initiators are combinations of persulfates and reducing agents, such as combinations of persulfates and sodium bisulfite, and combinations of peroxides and sodium ascorbate. The polymerization initiator can be only one type or two or more. The amount of polymerization initiator used can be any appropriate amount without impairing the effects of the invention. As such, the total amount relative to 100 parts by weight of the monomer component is, for example, 0.005 parts by weight to 1 part by weight, or 0.02 parts by weight to 0.5 parts by weight.

[0141] Examples of chain transfer agents include lauryl thiol, glycidyl thiol, mercaptoacetic acid, 2-mercaptoethanol, mercaptoacetic acid, 2-ethylhexyl mercaptoacetic acid, and 2,3-dimercapto-1-propanol. There may be only one chain transfer agent or two or more. The amount of chain transfer agent used can be any suitable amount without impairing the effects of the invention. Such an amount, in total, is, for example, 0.1 parts by weight or less relative to 100 parts by weight of the monomer components.

[0142] In radiation polymerization, monomers are polymerized by irradiating them with radiation such as electron beams or ultraviolet (UV) light to form a basic polymer. In electron beam radiation polymerization, the use of a photoinitiator is not particularly necessary. However, in UV radiation polymerization, a photoinitiator can be used due to advantages such as shortening polymerization time. A single photoinitiator or two or more photoinitiators can be used.

[0143] Examples of photopolymerization initiators include: benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-keto alcohol-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzoyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, and thioxanone-based photopolymerization initiators. The amount of photopolymerization initiator used can be any suitable amount without impairing the effects of the present invention. For example, such an amount is 0.05 to 1.5 parts by weight relative to 100 parts by weight of the monomer component, and can be 0.1 to 1 part by weight.

[0144] <1-2-b. Acrylic Adhesive Compositions>

[0145] In one embodiment of the invention, the adhesive sheet is composed of an acrylic adhesive formed from an acrylic adhesive composition comprising an acrylic polymer obtained by polymerizing monomer components.

[0146] As mentioned above, based on solid content, the acrylic polymer content in the acrylic adhesive composition is preferably 50% by weight or more, more preferably 70% by weight or more, and even more preferably 90% by weight or more.

[0147] Acrylic adhesive compositions may contain crosslinking agents. There may be only one type of crosslinking agent, or there may be two or more.

[0148] Examples of crosslinking agents that may be included in acrylic adhesive compositions include: isocyanate crosslinking agents, peroxide crosslinking agents, epoxy crosslinking agents, imine crosslinking agents, and multifunctional metal chelates. Preferably, the crosslinking agent included in the acrylic adhesive composition is selected from at least one of isocyanate crosslinking agents, epoxy crosslinking agents, and peroxide crosslinking agents; more preferably, it is selected from at least one of isocyanate crosslinking agents and peroxide crosslinking agents; and even more preferably, it is an isocyanate crosslinking agent.

[0149] The individual types of crosslinking agents that can be selected as crosslinking agents (e.g., isocyanate crosslinking agents) can be only one or more.

[0150] As isocyanate crosslinking agents, compounds having at least two isocyanate groups (isocyanate compounds) can be used. The number of isocyanate groups in the isocyanate compound is preferably three or more. There is no particular upper limit to the number of isocyanate groups, but for example, five. Examples of isocyanate compounds include aromatic isocyanate compounds, alicyclic isocyanate compounds, and aliphatic isocyanate compounds.

[0151] Examples of aromatic isocyanate compounds include: phenyl diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, and phenyldimethyl diisocyanate.

[0152] Examples of alicyclic isocyanate compounds include: 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated phenylenedimethylene diisocyanate, hydrogenated toluene diisocyanate, and hydrogenated tetramethylphenylenedimethylene diisocyanate.

[0153] Examples of aliphatic isocyanate compounds include: trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propene diisocyanate, 1,3-butene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

[0154] Examples of isocyanate crosslinking agents include: polymers (dimers, trimers, pentamers, etc.) of the aforementioned isocyanate compounds, adducts obtained by addition reactions with polyols such as trimethylolpropane, urea modifiers, biuret modifiers, urethane modifiers, isocyanurate modifiers, carbodiimide modifiers, and urethane prepolymers obtained by addition reactions with polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, polyisoprene polyols, etc.

[0155] Isocyanate crosslinking agents are preferably aromatic isocyanate compounds and their derivatives, more preferably toluene diisocyanate and its derivatives, in other words, toluene diisocyanate (TDI) crosslinking agents. From a reactivity point of view, TDI crosslinking agents are more suitable than dimethylolpropane diisocyanate and its derivatives, in other words, than dimethylolpropane diisocyanate (XDI) crosslinking agents. Isocyanate crosslinking agents may include adducts of polyols and toluene diisocyanate as TDI crosslinking agents. Specific examples of adducts are trimethylolpropane / toluene diisocyanate trimer adducts.

[0156] Commercially available isocyanate crosslinking agents can 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 Co., Ltd.). Among these, Takenate D-101E and Takenate D110N are preferred.

[0157] The amount of isocyanate crosslinking agent in the acrylic adhesive composition, relative to 100 parts by weight of the acrylic polymer, is, for example, 0.01 parts by weight to 20 parts by weight. The lower limit of the amount can be 0.02 parts by weight or more, 0.03 parts by weight or more, 0.04 parts by weight or more, or 0.05 parts by weight or more. The upper limit of the amount can 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, 0.5 parts by weight or less, 0.3 parts by weight or less, 0.1 parts by weight or less, or 0.08 parts by weight or less. A representative amount can be 0.03 parts by weight to 1 part by weight, or 0.05 parts by weight to 0.5 parts by weight.

[0158] Relative to 100 parts by weight of the base polymer, the amount of crosslinking agent (e.g., peroxide crosslinking agent) in the acrylic adhesive composition, excluding isocyanate crosslinking agents, is, for example, 2 parts by weight or less, 1 part by weight or less, or 0.5 parts by weight or less. The lower limit of the amount is, for example, 0.1 parts by weight or more, 0.2 parts by weight or more, or 0.3 parts by weight or more. A representative amount is 0.1 parts by weight to 1 part by weight, or 0.3 parts by weight to 0.5 parts by weight. The acrylic adhesive composition may also not contain crosslinking agents other than isocyanate crosslinking agents.

[0159] Acrylic adhesive compositions may further include known additives. Any suitable additive may be used without impairing the effects of the 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. Furthermore, redox systems containing reducing agents may be used within controllable limits. Any suitable amount of additive may be used without impairing the effects of the invention. For example, such an amount may be 10 parts by weight or less, 5 parts by weight or less, or even 1 part by weight or less, relative to 100 parts by weight of the acrylic polymer.

[0160] 2. Optical Laminates with Polarizing Films

[0161] In the optical laminate with polarizing film according to the embodiments of the present invention, a polarizing film is provided on the side of the first liquid crystal alignment fixing layer as viewed from the adhesive sheet included in the optical laminate according to the embodiments of the present invention.

[0162] The polarizing film can be directly laminated onto the first liquid crystal alignment fixing layer included in the optical laminate of the embodiments of the present invention, or it can be laminated via an interlayer adhesive (typically an adhesive).

[0163] Figure 2 This is a cross-sectional schematic diagram of an optical laminate with a polarizing film according to one embodiment of the present invention. Figure 2 The optical laminate 500 with polarizing film shown has a polarizing film 200, an adhesive layer 30 and an optical laminate 100 in sequence. The polarizing film 200 and the adhesive layer 30 are directly laminated together. The adhesive layer 30 is directly laminated together with the first liquid crystal alignment fixing layer 11. The first liquid crystal alignment fixing layer 11 is directly laminated together with the adhesive sheet 20. The adhesive sheet 20 is directly laminated together with the second liquid crystal alignment fixing layer 12.

[0164] 2-1. Polarizing Film

[0165] Typically, the polarizing film 200 includes a polarizer 40 and protective layers 51 and 52 disposed on both sides of the polarizer 40. At least one of the protective layers 51 and 52 may be omitted depending on the purpose. Therefore, the polarizing film can be a so-called double-protected polarizing film, a so-called single-protected polarizing film, or it can be composed solely of the polarizer.

[0166] <2-1-a. Polarizing Filter>

[0167] Typically, a polarizer is made of a film formed from 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 copolymers, and partially saponified ethylene-vinyl acetate copolymers.

[0168] The PVA-type resin preferably includes PVA-type resin modified with acetyl groups. When the total PVA-type resin is set at 100% by weight, the amount of the acetyl-modified PVA-type resin is preferably 5% to 20% by weight, more preferably 8% to 12% by weight.

[0169] The polarizer preferably contains iodides or sodium chloride (sometimes collectively referred to as halides). Examples of iodides include potassium iodide, sodium iodide, and lithium iodide. The content of halide in the polarizer is preferably 5 to 20 parts by weight, more preferably 10 to 15 parts by weight, relative to 100 parts by weight of PVA resin. In the manufacturing method described later, the halide can be incorporated into a coating solution forming a PVA resin layer as a precursor for the polarizer, and then finally introduced into the polarizer. By introducing the halide into the polarizer, the orientation of PVA molecules in the polarizer can be improved, thus enabling the realization of a polarizer with excellent optical properties (typically combining high polarization and high monomer transmittance).

[0170] The polarizer preferably exhibits absorption dichroism at any wavelength from 380 nm to 780 nm. The single-unit transmittance of the polarizer is preferably 41.0% to 46.0%, more preferably 42.0% to 45.0%. The polarization degree of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and even more preferably 99.9% or more.

[0171] The thickness of the polarizer is, for example, 12 μm or less, preferably 10 μm or less, more preferably 1 μm to 8 μm, and even more preferably 3 μm to 7 μm. By combining such a thin polarizer with a liquid crystal alignment fixing layer, a significant reduction in the thinness of the optical laminate can be achieved.

[0172] Polarizers can be manufactured using any suitable method. For example, the resin film forming the polarizer can be a single layer or a laminate of two or more layers.

[0173] Specific examples of polarizers composed of single-layer resin films include: films obtained by dyeing and stretching hydrophilic polymer films such as PVA films, partially methyl acetalized PVA films, and partially saponified ethylene / vinyl acetate copolymer films using dichroic substances such as iodine and dichroic dyes; and polyene-oriented films such as dehydrated PVA products and dehydrochlorinated polyvinyl chloride products. From the viewpoint of superior optical properties, polarizers obtained by dyeing PVA films with iodine and uniaxially stretching them are preferred.

[0174] The aforementioned iodine-based dyeing can be performed, for example, by immersing a PVA film in an aqueous iodine solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. Stretching can be performed after dyeing or during dyeing. Alternatively, dyeing can be performed after stretching. The PVA film can be subjected to swelling treatment, crosslinking treatment, cleaning treatment, drying treatment, etc., as needed. For example, by immersing the PVA film in water for washing before dyeing, not only can stains and anti-blocking agents on the surface of the PVA film be removed, but the PVA film can also swell to prevent uneven dyeing.

[0175] Specific examples of polarizing lenses made from laminated structures include those using a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or those using a resin substrate and a PVA-based resin layer coated on the resin substrate. A polarizing lens obtained using a resin substrate and a PVA-based resin layer coated on the resin substrate can be manufactured, for example, by coating a PVA-based resin solution onto a resin substrate, allowing it to dry, forming a PVA-based resin layer on the resin substrate, thus obtaining a laminate of the resin substrate and the PVA-based resin layer; stretching and dyeing the laminate to form a polarizing lens from the PVA-based resin layer. Preferably, a polyvinyl alcohol resin layer comprising a halide and a polyvinyl alcohol resin is formed on one side of the resin substrate.

[0176] Stretching typically involves immersing the polarizer of the laminate in an aqueous boric acid solution for stretching. Further stretching may be required, including stretching the laminate in a gas atmosphere at a high temperature (e.g., above 95°C) prior to stretching in the aqueous boric acid solution. Preferably, the laminate is subjected to a drying shrinkage treatment, where it shrinks by more than 2% in the width direction by heating while being transported along its length. Typical examples include sequentially performing assisted stretching in a gas atmosphere, dyeing, stretching in an aqueous solution, and drying shrinkage on the laminate. By introducing assisted stretching, even when PVA is coated on a thermoplastic resin, the crystallinity of PVA can be improved, resulting in high optical properties. Furthermore, by simultaneously improving the orientation of PVA beforehand, problems such as decreased orientation and dissolution of PVA during subsequent dyeing and stretching processes and immersion in water can be prevented, further achieving high optical properties. Moreover, when the PVA resin layer is immersed in a liquid, compared to the case where the PVA resin layer does not contain halides, the orientation disorder of polyvinyl alcohol molecules and the reduction of orientation can be suppressed. Therefore, the optical properties of the polarizer obtained by immersing the laminate in a liquid through processes such as dyeing and stretching in an aqueous solution can be improved. Furthermore, by shrinking the laminate in the width direction through a drying shrinkage process, optical properties can be further improved. The resulting resin substrate / polarizer laminate can be used directly (i.e., the resin substrate can be used as a protective layer for the polarizer), or the resin substrate can be peeled off from the resin substrate / polarizer laminate, and any suitable protective layer corresponding to the purpose can be laminated on the peeled surface or on the side opposite to the peeled surface. Detailed descriptions of such a method for manufacturing a polarizer are provided, 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.

[0177] <2-1-b. Protective Layer>

[0178] Typically, the protective layers disposed on both sides of the polarizer can be composed of any suitable resin film. Representative materials constituting such resin films include: cellulose resins such as cellulose triacetate (TAC), cyclic olefin 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. Representative examples of (meth)acrylic resins include (meth)acrylic resins having a lactone ring structure. (Meth)acrylic resins having a lactone ring structure are described, for example, in Japanese Patent Application Publication Nos. 2000-230016, 2001-151814, 2002-120326, 2002-254544, and 2005-146084. These publications are incorporated herein by reference. From the viewpoint of ease of processing irregular shapes, cellulose-based resins are preferred, and TAC is more preferred. From the viewpoint of obtaining polarizers with low moisture permeability and excellent durability, cyclic olefin resins and (meth)acrylic resins are preferred.

[0179] The protective layer can be surface-treated as needed. Examples of surface treatments include: hard coating, anti-reflective treatment, anti-adhesion treatment, and anti-glare treatment. The protective layer can also be treated to improve visual legibility when viewed through polarized sunglasses (typically, to impart (ellipsoidally) polarized light or to provide an ultra-high phase difference). By implementing such treatments, excellent visual legibility can be achieved even when viewing the display image through polarizing crystals such as polarized sunglasses.

[0180] The protective layer can be optically isotropic. For example, the in-plane phase difference Re(550) can be 0 nm to 10 nm, and the phase difference Rth(550) in the thickness direction can be -10 nm to +10 nm.

[0181] The thickness of the protective layer is preferably 10 μm to 80 μm, more preferably 12 μm to 40 μm, and even more preferably 15 μm to 35 μm. It should be noted that when the protective layer has undergone surface treatment, the thickness of the protective layer includes the thickness of the surface treatment layer.

[0182] <2-2. Adhesive Layer>

[0183] In an optical laminate with a polarizing film according to one embodiment of the present invention, any suitable adhesive layer can be used as an adhesive layer that can be disposed between the polarizing film and the optical laminate, without impairing the effects of the present invention. Such an adhesive layer is typically bonded using ultraviolet-curable adhesives or water-based adhesives. Examples of water-based adhesives include isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl latex adhesives, waterborne polyurethane, and waterborne polyester. In addition to the above, electron beam-curable adhesives can also be used as adhesive layers. The adhesive layer may contain a metal compound filler.

[0184] 《3. Other embodiments including optical laminates》

[0185] In the optical laminate of the present invention, and in the optical laminate with polarizing film of the present invention, an adhesive layer may be provided on the side of the second liquid crystal alignment fixing layer opposite to the adhesive sheet.

[0186] Figure 3 This is a cross-sectional schematic diagram illustrating an embodiment of the present invention in which an adhesive layer is provided on the side of the second liquid crystal alignment fixing layer of the optical laminate with a polarizing film opposite to the adhesive sheet. Figure 3 The laminate 600 shown has a polarizing film 200, an adhesive layer 30, an optical laminate 100, and an adhesive layer 60 in sequence. The polarizing film 200 is directly laminated with the adhesive layer 30, the adhesive layer 30 is directly laminated with the first liquid crystal alignment fixing layer 11, the first liquid crystal alignment fixing layer 11 is directly laminated with the adhesive sheet 20, the adhesive sheet 20 is directly laminated with the second liquid crystal alignment fixing layer 12, and the second liquid crystal alignment fixing layer 12 is directly laminated with the adhesive layer 60.

[0187] As an adhesive layer, any suitable adhesive layer can be used without impairing the effects of the present invention. For example, an adhesive layer formed from a known adhesive used in the bonding of optical components can be used. Preferably, an adhesive layer composed of a known acrylic adhesive is an example of such an adhesive layer.

[0188] A release liner can be provided on the surface of the adhesive layer. Examples of release liners include films, papers, fabrics, nonwovens, porous materials, meshes, foams, foils, or laminates thereof made of resins, paper, fibers, metals, or composites thereof. Examples of resins include: polyethylene, polypropylene, polybutene, polybutadiene, polymethylpentene, polyvinyl chloride, vinyl chloride copolymers, polyethylene terephthalate, polybutylene terephthalate, polyurethane, and ethylene-vinyl acetate copolymers.

[0189] The thickness of the release liner can be, for example, 5μm to 200μm, or 5 to 100μm. Various surface treatments, such as demolding treatment, anti-fouling treatment, and anti-static treatment, can be applied to the surface of the release liner as needed.

[0190] 4. Image Display Devices

[0191] The image display device according to an embodiment of the present invention includes the optical laminate according to an embodiment of the present invention.

[0192] Representative examples of image display devices include liquid crystal displays and organic EL displays. Typically, the image display device according to an embodiment of the present invention includes an optical laminate according to an embodiment of the present invention on its visual recognition side.

[0193] 5. Adhesive Sheets

[0194] In the adhesive sheet described in section 1-2, "Adhesive Sheet," adhesive sheets with a thickness of less than 20 μm, an average refractive index n of 1.50 or higher, and an indentation hardness greater than 0.010 MPa at 25°C, when used in optical laminates, exhibit a very high effect in suppressing the generation of linear non-uniformity and a very high effect in reducing depressions caused by localized loads. Such adhesive sheets can be used as embodiments of the present invention. Specifically, the adhesive sheet of the embodiments of the present invention has a thickness of less than 20 μm, an average refractive index n of 1.50 or higher, and an indentation hardness greater than 0.010 MPa at 25°C.

[0195] The adhesive sheet according to embodiments of the present invention may be useful not only in its use in the optical laminate of the present invention, i.e., in its use between the first liquid crystal alignment fixing layer and the second liquid crystal alignment fixing layer, but also in other uses. The adhesive sheet according to embodiments of the present invention is preferably used for bonding liquid crystal alignment fixing layers.

[0196] For the thickness of the adhesive sheet in the embodiments of the present invention, the description in the preceding section "1. Optical Laminates" can be referenced.

[0197] Typically, the average refractive index n of the adhesive sheet in embodiments of the present invention is 1.50 or more, preferably 1.52 or more, more preferably 1.54 or more, even more preferably 1.56 or more, and particularly preferably 1.57 or more. The upper limit of the average refractive index n of the adhesive sheet is preferably 1.70 or less.

[0198] Typically, the indentation hardness of the adhesive sheet in embodiments of the present invention at 25°C is greater than 0.010 MPa, preferably greater than 0.010 MPa and less than 0.157 MPa, more preferably 0.020 MPa to 0.130 MPa, further preferably 0.030 MPa to 0.100 MPa, particularly preferably 0.040 MPa to 0.090 MPa, and most preferably 0.045 MPa to 0.080 MPa. By adjusting the indentation hardness to the above range, the effects of the present invention can be further demonstrated, in particular, indentations caused by localized loads can be effectively reduced. If the indentation hardness is too low, the adhesive sheet is too soft, posing a risk of indentations caused by localized loads. On the other hand, if the indentation hardness is too high, the adhesive sheet is too hard, posing a risk of reduced adhesion between the adhesive sheet and adjacent optical components (e.g., liquid crystal alignment fixing layers).

[0199] It should be noted that, as the method for measuring the indentation hardness described above, a method capable of appropriately measuring the indentation hardness of the adhesive sheet according to the embodiments of the present invention can be used. For example, such a method can be performed using the method described in the embodiments, using a laminate having a structure of polarizing film / adhesive / first liquid crystal alignment fixing layer / adhesive sheet / second liquid crystal alignment fixing layer / adhesive sheet / release liner as the evaluation sample, or using a laminate having a structure of adhesive sheet / release liner as the evaluation sample.

[0200] As described below, the measurement method in the above-mentioned indentation hardness examples is as follows: A laminate consisting of a polarizing film / adhesive / first liquid crystal alignment fixing layer / adhesive sheet / second liquid crystal alignment fixing layer / adhesive sheet / release liner obtained in the examples / comparative examples is used as an evaluation sample. It is cut into 3mm×5mm pieces, and a cross-section is made using an ultramicrotome (LEICA, device name: Leica EM UC7) under freezing conditions at -60°C. It is then fixed to a given support (a brass base block of about 10mm×8mm×6mm). Under a gas atmosphere at 25°C, a micro-indentation hardness tester (nano-indenter) (Hysitron Inc. Triboindenter) is used, and a Berkovich (triangular pyramid) indenter is used to measure the indentation hardness when the adhesive sheet is indented to 1000nm.

[0201] Typically, the adhesive sheet in embodiments of the present invention is composed of an adhesive. Examples of such adhesives include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. From the viewpoint of further demonstrating the effects of the present invention, the adhesive sheet is preferably composed of an acrylic adhesive, which is formed from an acrylic adhesive composition comprising an acrylic polymer obtained by polymerizing monomer components. Sometimes, the main polymer component contained in such an acrylic polymer adhesive composition is referred to as the base polymer. The content of the base polymer in the adhesive composition is, for example, 50% by weight or more, 60% by weight or more, 70% by weight or more, 80% by weight or more, or 90% by weight or more. The upper limit of the content of the base polymer in the adhesive composition is, for example, 99.9% by weight or less, 99% by weight or less, or 95% by weight or less.

[0202] Without impairing the effects of the present invention, the adhesive sheet of the embodiments of the present invention can be formed by any suitable method. As such a forming method, the description in section 1-2, "Adhesive Sheet", above can be referenced.

[0203] A representative embodiment of the adhesive sheet of the present invention is an adhesive sheet made of an acrylic adhesive, which is formed from an acrylic adhesive composition comprising an acrylic polymer. Regarding such acrylic polymers and acrylic adhesive compositions, the descriptions in <1-2-a. Acrylic Polymers> and <1-2-b. Acrylic Adhesive Compositions> above can be referenced.

[0204] A release liner can be provided on the surface of the adhesive sheet. Examples of release liners include films, papers, fabrics, nonwovens, porous materials, meshes, foams, foils, or laminates thereof, made of resin, paper, fiber, metal, or composites thereof. Examples of resins include: polyethylene, polypropylene, polybutene, polybutadiene, polymethylpentene, polyvinyl chloride, vinyl chloride copolymers, polyethylene terephthalate, polybutylene terephthalate, polyurethane, and ethylene-vinyl acetate copolymers.

[0205] The thickness of the release liner can be, for example, 5μm to 200μm, or 5 to 100μm. Various surface treatments, such as demolding treatment, anti-fouling treatment, and antistatic treatment, can be applied to the surface of the release liner as needed.

[0206] Example

[0207] The present invention will now be specifically described through embodiments, but the present invention is not limited to these embodiments in any way. It should be noted that the testing and evaluation methods in the embodiments are as described below. It should be noted that, unless otherwise stated, when "parts" is used, it refers to "parts by weight," and when "%" is used, it refers to "% by weight."

[0208] <Thickness Measurement>

[0209] The measurements were performed using an interferometric film thickness gauge (manufactured by Otsuka Electronics Co., Ltd., "MCPD9800").

[0210] <Determination of Refractive Index>

[0211] [Refractive index of the adhesive sheet]

[0212] The refractive index of the adhesive sheet was measured using an Abbe refractometer (ATAGO, product name "DR-M2 / 1550"). The measurement wavelength was 589 nm and the measurement temperature was 25 °C.

[0213] [Refractive index of the liquid crystal alignment fixing layer]

[0214] Regarding the refractive index of the liquid crystal alignment fixing layer, the refractive index along the transmission axis was determined as follows. The in-plane phase difference Re(550°) and the thickness-direction phase difference Rth(550°) were measured using an Axoscan (manufactured by Axometrics). nx, ny, and nz were calculated using the following simultaneous equations.

[0215] Re(550)=(nx-ny)×d

[0216] Nz=Rth(550) / Re(550)=(nx-nz) / (nx-ny)

[0217] Furthermore, in the equation (x² / a²) + (y² / b²) = 1 for the ellipse, let a be nx, let b be ny, and let x and y be the refractive indices in the x and y directions along the angle θ on the ellipse. Solve the simultaneous equations based on y = tanθ and the aforementioned nx and ny to calculate the refractive index along the transmission axis.

[0218] <Determination of Indentation Hardness>

[0219] The laminate having the structure of a polarizing film / adhesive / first liquid crystal alignment fixing layer / adhesive sheet / release liner obtained from the examples and comparative examples, after removing the release liner, was used as an evaluation sample, cut into 3 mm × 5 mm, and a cross-section was prepared using an ultramicrotome (manufactured by LEICA, device name: Leica EM UC7) under freezing conditions at -60°C, and then fixed to a given support (a brass base block of about 10 mm × 8 mm × 6 mm).

[0220] Under a 25°C gas atmosphere, using a micro-indentation hardness tester (nanoindentation) (Triboindenter manufactured by Hysitron Inc.), the indentation hardness was measured when the adhesive surface was indented by 1000 nm using a Berkovich (triangular pyramid) indenter.

[0221] <Measurement of Tg>

[0222] A laminate with a thickness of about 1 mm was prepared by laminating adhesive sheets, and used as a measurement sample. Dynamic viscoelasticity was measured using ARES-G2 (manufactured by TA Instruments) under the following conditions, and the temperature (peak temperature) at which the loss tangent (tanδ) reached the maximum was taken as the glass transition temperature (Tg) of the adhesive sheet.

[0223] (Measurement conditions)

[0224] Deformation mode: Torsion

[0225] Measurement frequency: 1 Hz

[0226] Heating rate: 5°C / min

[0227] Shape: Parallel plates, 8 mm Φ

[0228] <Evaluation of linear unevenness>

[0229] The acrylic adhesive manufactured in Production Example 12 was disposed on the second liquid crystal alignment fixing layer side of the optical laminate obtained in the examples and comparative examples, and bonded to a V3 reflector (manufactured by NEODIS) through this acrylic adhesive to prepare a test sample. The test sample obtained was visually observed under a 3-wavelength fluorescent lamp and evaluated according to the following criteria.

[0230] ◎: No linear unevenness was observed

[0231] ○: Slight linear unevenness was observed

[0232] △: Although linear unevenness was observed, it was at an acceptable level for practical use

[0233] ×: Obvious linear unevenness

[0234] <Determination of Injection Load>

[0235] The laminate consisting of polarizing film / adhesive / first liquid crystal alignment fixing layer / adhesive sheet / second liquid crystal alignment fixing layer / adhesive sheet / release liner obtained in the examples and comparative examples was used as the evaluation sample. It was cut into 1 cm squares, and the outermost adhesive layer was fixed to a given support (Matsunami Glass Industry Co., Ltd., Slide Glass) and used as the test sample.

[0236] In a gas atmosphere at 25°C, the indentation load when indented to 40 μm from the outermost layer of the polarizing film was determined using a micro-indentation hardness tester (nano-indentation) (ELIONIX ENT-NEXUS) and a Berkovich (triangular pyramid) indenter.

[0237] Evaluation of indentations caused by localized loads

[0238] A laminate consisting of a polarizing film / adhesive / first liquid crystal alignment fixing layer / adhesive sheet / second liquid crystal alignment fixing layer / adhesive sheet / release liner obtained in the examples and comparative examples was cut into 1 cm long and 1 cm wide pieces to prepare a sample. The release liner was peeled off, and the exposed adhesive sheet was attached to an aluminum reflector (manufactured by Toray Advanced Film, trade name: CerapeelDMS-X42, total light reflectivity: 86%). Next, the sample was placed on a glass plate (manufactured by Matsunami Glass Industry Co., Ltd., thickness = 0.7 mm) with the polarizing film side of the sample in contact with the glass plate. Then, a weight was placed on a conical indenter (diameter 1.5 mm, height 0.8 mm) with a PET sheet (manufactured by TORAY, thickness = 80 μm) sandwiched between the aluminum reflector side and pressed in for 30 seconds. The weight (load) of the weight was set to 400 g (2.2 MPa) and measured. Then, remove the weights and indenter. For the surface of the sample in contact with the glass plate, visually observe the reflection around the azimuth angle at a polar angle of 30°~60° to confirm the presence of an indentation. It should be noted that when the surface of the sample is set as the X-axis and Y-axis, and the axis perpendicular to the XY plane is set as the Z-axis, the angle tilted from the Z-axis towards the XY plane is set as the polar angle (θ), the MD direction of the polarizing film is set as 0°, and the measured angle along the direction of counterclockwise rotation relative to the MD direction of the polarizing film is evaluated as the azimuth angle (φ).

[0239] It should be noted that the visual recognizability of a depression depends not only on the actual amount of depression, but also on the greater the difference in refractive index between the liquid crystal alignment fixing layer and the adhesive layer, the easier it is to visually recognize.

[0240] The depression was evaluated according to the following criteria.

[0241] ◎: There are no visually recognizable depressions.

[0242] ○: Slight dents are visually identifiable, but the level does not pose a problem in actual use.

[0243] △: The dent is visually identifiable, but there is no problem in actual use.

[0244] ×: Visually identifiable dents (indentations) indicate a level of problem in actual use.

[0245] <Evaluation of Fit>

[0246] The second liquid crystal alignment fixing layer of the optical laminate with polarizing film obtained in the examples and comparative examples was bonded to a polyethylene terephthalate (PET) film (manufactured by TORAY, trade name: Lumirror, thickness = 125 μm). An adhesive (manufactured by Monotaro, trade name: Motto Kuttsuke Taro) was used for bonding. Bonding was performed in a gas atmosphere at 25°C using a 2 kg pressing roller as specified in JIS Z0237:2009, ensuring that no air bubbles were present between the second liquid crystal alignment fixing layer and the PET film during bonding.

[0247] After being left to stand for 2 days after bonding, a 25mm x 150mm shape was cut out and bonded to the surface of a stainless steel (SUS) plate used as a test board using an adhesive sheet (manufactured by Nitto Denko Corporation, trade name: No. 500). Bonding was carried out in a gas atmosphere at 25°C using a 2kg pressing roller as specified in JIS Z0237:2009.

[0248] Next, in a gas atmosphere at 25±5°C, using a tensile testing machine (manufactured by Shimadzu Corporation, trade name: Autograph AG-X), with a peel angle of 90° and a peel speed of 300 mm / min, the laminated portion (laminated portion P) of the polarizing film / adhesive / first liquid crystal alignment fixing layer / adhesive sheet was peeled from the laminated portion (laminated portion Q) of the second liquid crystal alignment fixing layer / adhesive / PET film / adhesive sheet / SUS board along the long side direction.

[0249] The evaluation was conducted according to the following criteria.

[0250] ○: During the peeling process, the first liquid crystal alignment fixing layer and the second liquid crystal alignment fixing layer are fully bonded together.

[0251] △: When performing the peeling, although the peeling is slightly lighter, it is at a level that does not pose a problem in actual use.

[0252] ×: When peeling, it peels off easily, resulting in insufficient adhesion.

[0253] [Manufacturing Example 1] Fabrication of the First Liquid Crystal Alignment Fixing Layer

[0254] A photopolymerizable liquid crystal compound exhibiting a nematic liquid crystal phase (Paliocolor LC242, manufactured by BASF, hereinafter chemical formula) was dissolved in cyclopentanone to prepare a solution with a solid content concentration of 30% by weight. A surfactant (BYK-Chemie, "BYK-360") and a photopolymerization initiator (IGM Resins, "Omnirad 907") were added to this solution to prepare a liquid crystal composition solution. The amounts of surfactant and polymerization initiator added were set to 0.01 parts by weight and 3 parts by weight, respectively, relative to 100 parts by weight of the photopolymerizable liquid crystal compound. A biaxially stretched norbornene film (ZEONOR film, manufactured by Zeon Corporation, Japan, 33 μm thick, Re(550) = 135 nm) was prepared as a substrate. The above liquid crystal composition was coated onto the substrate using a bar coater to achieve a Re(550) of 240 nm, and the liquid crystal was oriented by heating at 100°C for 3 minutes. After cooling to room temperature, the cumulative light intensity was 400 mJ / cm under a nitrogen atmosphere. 2 UV light was used for photocuring to obtain a laminate consisting of a substrate and a first liquid crystal alignment fixing layer. The first liquid crystal alignment fixing layer is homogeneous aligned, has a thickness of 1.7 μm, and an average refractive index of 1.590.

[0255] [Manufacturing Example 2]: Fabrication of the Second Liquid Crystal Alignment Fixing Layer

[0256] Except for changing the coating thickness, a laminate with a substrate / second liquid crystal alignment fixing layer (Re(550)=130nm) was obtained in the same manner as the fabrication of the first liquid crystal alignment fixing layer in Manufacturing Example 1. The second liquid crystal alignment fixing layer is surface-oriented, has a thickness of 0.92μm, and an average refractive index of 1.590.

[0257] [Manufacturing Example 3]: Fabrication of a Polarizing Filter

[0258] As a thermoplastic resin substrate, a strip-shaped amorphous polyethylene terephthalate copolymer (100 μm thickness) with a Tg of approximately 75 °C was used, and one side of the resin substrate was subjected to corona treatment. A PVA aqueous solution (coating solution) was prepared by adding 13 parts by weight of potassium iodide to 100 parts by weight of a PVA-based resin prepared by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER") in a 9:1 ratio, and dissolving the resulting mixture in water. The above PVA aqueous solution was coated onto the corona-treated side of the resin substrate and dried at 60 °C, thereby forming a 13 μm thick PVA-based resin layer, thus creating a laminate. The resulting laminate was then unidirectionally stretched to 2.4 times its original length in an oven at 130 °C (assisted stretching treatment in a gas atmosphere). Next, the laminate was immersed in an insoluble bath (a boric acid aqueous solution prepared by adding 4 parts by weight of boric acid to 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (insoluble treatment). Then, it was immersed in a dyeing bath (an iodine aqueous solution prepared by adding iodine and potassium iodide in a 1:7 weight ratio to 100 parts by weight of water) at a liquid temperature of 30°C for 60 seconds while adjusting the concentration (dyeing treatment) to achieve the desired monomer transmittance (Ts) of the final polarizer. Next, it was immersed in a crosslinking bath (a boric acid aqueous solution prepared by adding 3 parts by weight of potassium iodide and 5 parts by weight of boric acid to 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (crosslinking treatment). Then, while immersing the laminate in a boric acid aqueous solution (4 wt% boric acid and 5 wt% potassium iodide) at a liquid temperature of 70°C, it was unidirectionally stretched between rollers at different circumferential speeds along the longitudinal direction (length direction) to achieve a total stretch ratio of 5.5 times (stretching treatment in aqueous solution). The laminate was then immersed in a cleaning bath at a liquid temperature of 20°C (an aqueous solution of 100 parts by weight of water and 4 parts by weight of potassium iodide) (cleaning treatment). It was then dried in an oven maintained at approximately 90°C while its contact surface temperature was maintained at approximately 75°C using SUS heated rollers (drying shrinkage treatment). This resulted in the formation of a polarizer with a thickness of approximately 5 μm on the resin substrate, yielding a laminate with a resin substrate / polarizer configuration. The polarizer's single-unit transmittance Ts was 43.3%.

[0259] [Manufacturing Example 4]: Fabrication of Polarizing Film

[0260] An HC-COP film was bonded to the surface of the polarizer obtained in Manufacturing Example 3 (the side opposite to the resin substrate) using a UV-curable adhesive. It should be noted that the HC-COP film is a film with an HC layer (4 μm thick) formed on a cyclic olefin resin (COP) film (25 μm thick), and the COP film was bonded with the polarizer side facing out. The Re(550) of the COP film is 135 nm. Next, the resin substrate was peeled off, and a cellulose triacetate (TAC) film (25 μm thick) was bonded to the peeled surface using a UV-curable adhesive. Thus, a polarizing film having the structure of an HC layer / COP film (protective layer) / polarizer / TAC film (protective layer) was obtained.

[0261] [Manufacturing Example 5]: Adhesive for the laminated polarizing film and the first liquid crystal alignment fixing layer

[0262] The following ingredients were prepared: 10 parts by weight of hydroxyethyl acrylamide (trade name "HEAA", manufactured by KJ Chemicals), 4 parts by weight of 2-acetylacetoxyethyl methacrylate (trade name "AAEM", manufactured by Mitsubishi Chemical Corporation), 60 parts by weight of acrylmorpholine (trade name "ACMO", manufactured by KJ Chemicals), 11 parts by weight of tripropylene glycol diacrylate (trade name "ARONIX M-220"), 1 part by weight of 4-vinylphenylboronic acid (manufactured by Fuji Film & Kouichi Chemical Co., Ltd., manufactured by Toa Synthetic Co., Ltd.), 10 parts by weight of acrylic oligomer (trade name "ARUFON UP-1190", manufactured by Toa Synthetic Co., Ltd.), 1 part by weight of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (trade name "Omnirad819", manufactured by IGM Resins BV), and 1 part by weight of 1-hydroxycyclohexyl benzophenone (trade name "Omnirad184", manufactured by IGM Resins). An adhesive was prepared by stirring 2 parts by weight of BV (manufactured by BV) and 1 part by weight of diethylthioxanthone (trade name "KAYACUREDETX-S", manufactured by Nippon Kayaku Co., Ltd.) at 50°C for 1 hour.

[0263] [Manufacturing Example 6]: Acrylic polymer (1) and acrylic adhesive composition (1)

[0264] In a four-necked flask equipped with a stirrer, thermometer, nitrogen inlet pipe, and cooler, 85 parts by weight of phenoxybenzyl acrylate (POB-A), 2 parts by weight of 4-hydroxybutyl acrylate (4HBA), and 13 parts by weight of butyl acrylate (BA) were added. 0.1 parts by weight of 2,2'-azobisisobutyronitrile (AIBN), acting as a polymerization initiator, were added along with ethyl acetate, relative to 100 parts by weight of the monomer mixture. Nitrogen purging was performed by slowly stirring and introducing nitrogen gas. The liquid temperature in the flask was then maintained at approximately 55°C, and the polymerization reaction was carried out for 7 hours. The monomer concentration during polymerization was set to 40% by weight. Then, ethyl acetate was added to the resulting reaction solution to adjust the solid content concentration to 30%, thus preparing a solution of acrylic polymer (1).

[0265] Acrylic adhesive composition (1) was prepared by adding 0.2 parts by weight of isocyanate crosslinking agent (trimethylolpropane / phenylenedimethyl diisocyanate trimer adduct, manufactured by Mitsui Chemicals Co., Ltd., Takenate D-110N) to 100 parts by weight of the solid component of acrylic polymer (1), and adding ethyl acetate as a diluent to achieve a solid component content of 15%.

[0266] [Manufacturing Example 7]: Acrylic polymer (2) and acrylic adhesive composition (2)

[0267] In addition to 70 parts by weight of phenoxybenzyl acrylate (POB-A), 1 part by weight of 4-hydroxybutyl acrylate (4HBA), and 29 parts by weight of butyl acrylate (BA), 85 parts by weight of phenoxybenzyl acrylate (POB-A), 2 parts by weight of 4-hydroxybutyl acrylate (4HBA), and 13 parts by weight of butyl acrylate (BA) were added, the same procedure as in Manufacturing Example 6 was followed to prepare a solution of acrylic polymer (2) and an acrylic adhesive composition (2).

[0268] [Manufacturing Example 8]: Acrylic polymer (3) and acrylic adhesive composition (3)

[0269] 80 parts by weight of benzyl acrylate (BzA), 1 part by weight of 4-hydroxybutyl acrylate (4HBA), and 19 parts by weight of butyl acrylate (BA) were added instead of 85 parts by weight of phenoxybenzyl acrylate (POB-A), 2 parts by weight of 4-hydroxybutyl acrylate (4HBA), and 13 parts by weight of butyl acrylate (BA). Otherwise, the same procedure as in Manufacturing Example 6 was followed to prepare a solution of acrylic polymer (3) and an acrylic adhesive composition (3).

[0270] [Manufacturing Example 9]: Acrylic polymer (4) and acrylic adhesive composition (4)

[0271] In addition to 95 parts by weight of phenoxybenzyl acrylate (POB-A) and 5 parts by weight of 4-hydroxybutyl acrylate (4HBA), 85 parts by weight of phenoxybenzyl acrylate (POB-A), 2 parts by weight of 4-hydroxybutyl acrylate (4HBA), and 13 parts by weight of butyl acrylate (BA), the same procedure as in Manufacturing Example 6 was followed to prepare a solution of acrylic polymer (4) and an acrylic adhesive composition (4).

[0272] [Manufacturing Example 10]: Acrylic polymer (5) and acrylic adhesive composition (5)

[0273] A monomer mixture containing 91 parts by weight of butyl acrylate (BA), 6 parts by weight of acrylamide (trade name "ACMO", manufactured by KJ Chemicals), 2.7 parts by weight of acrylic acid (AA), and 0.3 parts by weight of 4-hydroxybutyl acrylate (4HBA) was added to a four-necked flask equipped with a stirring blade, thermometer, nitrogen inlet pipe, and cooler.

[0274] Relative to 100 parts by weight of the monomer mixture, 0.1 parts by weight of 2,2'-azobisisobutyronitrile (2,2'-azobisisobutyronitrile) as a polymerization initiator and 100 parts by weight of ethyl acetate were added together. Nitrogen gas was introduced while stirring slowly to perform nitrogen purging. Then, the liquid temperature in the flask was maintained at around 55°C for 8 hours to carry out the polymerization reaction and prepare a solution of acrylic polymer (5).

[0275] An acrylic adhesive composition (5) was prepared by combining 0.1 parts by weight of an isocyanate crosslinking agent (trimethylolpropane / toluene diisocyanate adduct, manufactured by Tosoh Corporation, trade name "Coronate L"), 0.3 parts by weight of a peroxide crosslinking agent (benzoyl peroxide, manufactured by Nippon Yushi Co., Ltd., trade name "Nyper BMT"), and 0.2 parts by weight of an epoxy-containing silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-403"). The polymer concentration of the acrylic adhesive composition (5) was adjusted to 5 parts by weight.

[0276] [Manufacturing Example 11]: Acrylic polymer (6) and acrylic adhesive composition (6)

[0277] A solution of acrylic polymer (6) was prepared by replacing 85 parts by weight of phenoxybenzyl acrylate (POB-A), 2 parts by weight of 4-hydroxybutyl acrylate (4HBA), and 13 parts by weight of butyl acrylate (BA) with 19 parts by weight of benzyl acrylate (BzA), 0.1 parts by weight of 4-hydroxybutyl acrylate (4HBA), 5 parts by weight of acrylic acid (AA), and 75.9 parts by weight of butyl acrylate (BA). Otherwise, the preparation was carried out in the same manner as in manufacturing example 6.

[0278] An acrylic adhesive composition (6) was prepared by mixing 0.45 parts by weight of an isocyanate crosslinking agent (trimethylolpropane / toluene diisocyanate adduct, manufactured by Tosoh Corporation, trade name "Coronate L"), 0.1 parts by weight of a peroxide crosslinking agent (benzoyl peroxide, manufactured by Nippon Oils & Fats Co., Ltd., trade name "Nyper BMT"), and 0.2 parts by weight of an epoxy-containing silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-403"). The polymer concentration of the acrylic adhesive composition (6) was adjusted to 5% by weight.

[0279] [Manufacturing Example 12]: Acrylic polymer (A) and acrylic adhesive composition (A)

[0280] A monomer mixture containing 94.9 parts by weight of butyl acrylate (BA), 5 parts by weight of acrylic acid, and 0.1 parts by weight of 2-hydroxyethyl acrylate (HEA) was added to a four-necked flask equipped with a stirrer, thermometer, nitrogen inlet pipe, and cooler. Further, relative to 100 parts by weight of this monomer mixture, 0.1 parts by weight of 2,2'-azobisisobutyronitrile (2,2'-Azobisisobutyronitrile) as a polymerization initiator and 100 parts by weight of ethyl acetate were added together. Nitrogen purging was performed by slowly stirring and introducing nitrogen gas. Then, the liquid temperature in the flask was maintained at approximately 55°C, and the polymerization reaction was carried out for 8 hours to prepare a solution of an acrylic polymer (A) with a weight-average molecular weight (Mw) of 2.2 million.

[0281] An acrylic adhesive composition (A) was prepared by combining 100 parts by weight of the solid component of the acrylic polymer (A) solution with 0.6 parts by weight of an isocyanate crosslinking agent (trimethylolpropane / toluene diisocyanate adduct: manufactured by Tosoh Corporation, trade name "Coronate L"), 0.2 parts by weight of a peroxide crosslinking agent (benzoyl peroxide: manufactured by Nippon Yushi Co., Ltd., trade name "Nyper BMT"), and 0.2 parts by weight of an epoxy-containing silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-403").

[0282] [Example 1]

[0283] Using the adhesive (1 μm thick) obtained in Manufacturing Example 5, the first liquid crystal alignment fixing layer side of the laminate having the substrate / first liquid crystal alignment fixing layer structure obtained in Manufacturing Example 1 is bonded to the TAC film side of the polarizing film. Then the substrate is peeled off to obtain a laminate having the structure of polarizing film / adhesive / first liquid crystal alignment fixing layer.

[0284] Next, the acrylic adhesive composition (1) obtained in Manufacturing Example 6 was coated onto the release liner (Mitsubishi Chemical Corporation, MRF38-NS2) to achieve a thickness of 5 μm after drying. It was then cured and dried at a drying temperature of 120°C and a drying time of 90 seconds, and then bonded to the plasma-irradiated first liquid crystal alignment fixing layer side of the above-mentioned laminate to obtain a laminate consisting of a polarizing film / adhesive / first liquid crystal alignment fixing layer / adhesive sheet (1) / release liner.

[0285] After peeling off the release liner, the second liquid crystal alignment layer side of the laminate having the substrate / second liquid crystal alignment layer obtained in manufacturing example 2 is corona irradiated and then attached to the adhesive sheet (1) side of the laminate. The substrate is then peeled off to obtain an optical laminate with a polarizing film having the structure of polarizing film / adhesive / first liquid crystal alignment layer / adhesive sheet (1) / second liquid crystal alignment layer.

[0286] The acrylic adhesive composition (A) obtained in Manufacturing Example 12 was coated onto a release liner (Mitsubishi Chemical Corporation, MRF38-NS2) to achieve a thickness of 25 μm after drying. The liner was then cured and dried at a drying temperature of 155°C for 90 seconds to obtain a laminate of adhesive sheet (A) / release liner.

[0287] The surface of the second liquid crystal alignment fixing layer of the optical laminate with polarizing film, which is composed of polarizing film / adhesive / first liquid crystal alignment fixing layer / adhesive sheet (1) / second liquid crystal alignment fixing layer, is corona irradiated, and the adhesive sheet (A) side of the laminate with adhesive sheet (A) / release liner is attached to the corona-treated surface.

[0288] Thus, an optical laminate (1) with a polarizing film is obtained, consisting of a polarizing film, an adhesive, a first liquid crystal alignment fixing layer, an adhesive sheet (1), a second liquid crystal alignment fixing layer, an adhesive sheet (A), and a release liner.

[0289] In the optical laminate (1) with a polarizing film, the angle between the transmission axis of the polarizing mirror of the polarizing film and the slow axis of the first liquid crystal alignment fixing layer is 15°, and the angle between the transmission axis of the polarizing mirror of the polarizing film and the slow axis of the second liquid crystal alignment fixing layer is 75°.

[0290] The average refractive index of the first liquid crystal alignment fixing layer and the second liquid crystal alignment fixing layer is 1.59. The refractive index nLC1 of the first liquid crystal alignment fixing layer in the transmission axis direction of the polarizer is 1.66, and the refractive index nLC2 of the second liquid crystal alignment fixing layer in the transmission axis direction of the polarizer is 1.56.

[0291] The results are shown in Table 1.

[0292] [Example 2]

[0293] The acrylic adhesive composition (1) obtained in Manufacturing Example 6 was coated with a thickness of 10 μm after drying. Otherwise, the process was carried out in the same manner as in Example 1, and an optical laminate (2) with a polarizing film was obtained, consisting of a polarizing film / adhesive / first liquid crystal alignment fixing layer / adhesive sheet (2) / second liquid crystal alignment fixing layer / adhesive sheet (A) / release liner.

[0294] The results are shown in Table 1.

[0295] [Example 3]

[0296] The acrylic adhesive composition (2) obtained in Manufacturing Example 7 was used instead of the acrylic adhesive composition (1) obtained in Manufacturing Example 6. Otherwise, the process was carried out in the same manner as in Example 1, and an optical laminate (3) consisting of polarizing film / adhesive / first liquid crystal alignment fixing layer / adhesive sheet (3) / second liquid crystal alignment fixing layer / adhesive sheet (A) / release liner was obtained.

[0297] The results are shown in Table 1.

[0298] [Example 4]

[0299] The acrylic adhesive composition (3) obtained in Manufacturing Example 8 was used instead of the acrylic adhesive composition (1) obtained in Manufacturing Example 6. Otherwise, the process was carried out in the same manner as in Example 1, and an optical laminate (4) consisting of polarizing film / adhesive / first liquid crystal alignment fixing layer / adhesive sheet (4) / second liquid crystal alignment fixing layer / adhesive sheet (A) / release liner was obtained.

[0300] The results are shown in Table 1.

[0301] [Example 5]

[0302] The acrylic adhesive composition (4) obtained in Manufacturing Example 9 was used instead of the acrylic adhesive composition (1) obtained in Manufacturing Example 6. Otherwise, the process was carried out in the same manner as in Example 1, and an optical laminate (5) with a polarizing film was obtained, consisting of a polarizing film / adhesive / first liquid crystal alignment fixing layer / adhesive sheet (5) / second liquid crystal alignment fixing layer / adhesive sheet (A) / release liner.

[0303] The results are shown in Table 1.

[0304] [Comparative Example 1]

[0305] The acrylic adhesive composition (5) obtained in Manufacturing Example 10 was used instead of the acrylic adhesive composition (1) obtained in Manufacturing Example 6. Otherwise, the process was carried out in the same manner as in Example 1, and an optical laminate (C1) with a polarizing film consisting of polarizing film / adhesive / first liquid crystal alignment fixing layer / adhesive sheet (C1) / second liquid crystal alignment fixing layer / adhesive sheet (A) / release liner was obtained.

[0306] The results are shown in Table 1.

[0307] [Comparative Example 2]

[0308] The acrylic adhesive composition (6) obtained in Manufacturing Example 11 was used instead of the acrylic adhesive composition (1) obtained in Manufacturing Example 6. Otherwise, the process was carried out in the same manner as in Example 1, and an optical laminate (C2) with a polarizing film consisting of polarizing film / adhesive / first liquid crystal alignment fixing layer / adhesive sheet (C2) / second liquid crystal alignment fixing layer / adhesive sheet (A) / release liner was obtained.

[0309] The results are shown in Table 1.

[0310] [Comparative Example 3]

[0311] The acrylic adhesive composition (1) obtained in Manufacturing Example 6 was coated with a thickness of 20 μm after drying. Otherwise, the process was carried out in the same manner as in Example 1, and an optical laminate (C3) with a polarizing film was obtained, consisting of a polarizing film / adhesive / first liquid crystal alignment fixing layer / adhesive sheet (C3) / second liquid crystal alignment fixing layer / adhesive sheet (A) / release liner.

[0312] The results are shown in Table 1.

[0313] [Table 1]

[0314]

[0315] Industrial applicability

[0316] The optical laminate of the embodiments of the present invention can be suitably used in image display devices (typically liquid crystal display devices and organic EL display devices).

Claims

1. An optical laminate, comprising, in sequence: a first liquid crystal alignment fixing layer, an adhesive sheet, and a second liquid crystal alignment fixing layer, The thickness of the adhesive sheet is less than 20 μm. When the average refractive index of the adhesive sheet is set to n, the average refractive index of the first liquid crystal alignment fixing layer is set to n1, and the average refractive index of the second liquid crystal alignment fixing layer is set to n2, the largest average refractive index difference selected from the average refractive index difference calculated using |n-n1| and the average refractive index difference calculated using |n-n2| is less than 0.

11. The adhesive sheet has an indentation hardness greater than 0.019 MPa at 25°C.

2. The optical laminate according to claim 1, wherein, The adhesive sheet is made of an acrylic adhesive, which is formed from an acrylic adhesive composition comprising an acrylic polymer obtained by polymerizing monomer components.

3. The optical laminate according to claim 2, wherein, The Tg of the acrylic polymer is below 13°C.

4. The optical laminate according to claim 1, wherein, The indentation hardness is less than 0.157 MPa.

5. The optical laminate according to claim 1, wherein, The thickness of the adhesive sheet is 4 μm or more.

6. The optical laminate according to claim 1, wherein, The average refractive index n of the adhesive sheet is 1.52 or higher.

7. The optical laminate according to claim 1, wherein, A polarizing film is provided on at least one side selected from the first liquid crystal alignment fixing layer side and the second liquid crystal alignment fixing layer side as viewed from the adhesive sheet.

8. An optical laminate with a polarizing film, wherein the polarizing film is provided on the side of the first liquid crystal alignment fixing layer as viewed from the adhesive sheet of the optical laminate according to any one of claims 1 to 6.

9. An optical laminate with a polarizing film, wherein the polarizing film is provided on the side of the second liquid crystal alignment fixing layer as viewed from the adhesive sheet of the optical laminate according to any one of claims 1 to 6.

10. An image display device comprising an optical laminate according to any one of claims 1 to 7.

11. An adhesive sheet having a thickness of less than 20 μm, The average refractive index n is above 1.

50. The indentation hardness at 25℃ is greater than 0.019MPa.

12. The adhesive sheet of claim 11, comprising an acrylic adhesive formed from an acrylic adhesive composition comprising an acrylic polymer obtained by polymerizing monomer components.

13. The adhesive sheet according to claim 12, wherein, The Tg of the acrylic polymer is below 13°C.

14. The adhesive sheet according to claim 11, wherein, The indentation hardness is less than 0.157 MPa.

15. The adhesive sheet according to claim 11, wherein, The average refractive index n is 1.54 or higher.

16. The adhesive sheet according to any one of claims 11 to 15, used for bonding liquid crystal alignment fixing layers.

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