Optical laminate and image display device

Abstract

Provided is an optical laminate comprising a first liquid crystal layer and a first adhesive sheet adjacent to the first liquid crystal layer. The glass transition temperature (Tg) of the first adhesive sheet is -10°C or higher. Although the optical laminate comprises the liquid crystal layer and the adhesive sheet adjacent to the liquid crystal layer, the optical laminate is suitable for use in an image display device that can be exposed to a temperature change to an extremely low temperature. The optical laminate may have a ratio [G'(-40°C) / G'(-10°C)] of the storage elastic modulus G'(-40°C) of the first adhesive sheet at -40°C to the storage elastic modulus G'(-10°C) of the first adhesive sheet at -10°C of 50 or less.

Description

Optical laminates and image display devices

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

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

[0003] Japanese Patent Publication No. 2020-140212

[0004] According to the inventors' research, in an optical laminate comprising a liquid crystal layer and an adjacent adhesive sheet, cracks tend to occur and expand when exposed to extremely low temperature changes.

[0005] The present invention aims to provide an optical laminate that comprises a liquid crystal layer and an adjacent adhesive sheet, yet is suitable for use in image display devices that may be exposed to extremely low temperature changes.

[0006] [1] An optical laminate according to an embodiment of the present invention comprises a first liquid crystal layer and a first adhesive sheet adjacent to the first liquid crystal layer, wherein the glass transition temperature (Tg) of the first adhesive sheet is -10°C or higher. [2] In the optical laminate described in [1] above, the ratio of the storage modulus of the first adhesive sheet at -40°C G'(-40°C) to the storage modulus of the first adhesive sheet at -10°C G'(-10°C) [G'(-40°C) / G'(-10°C)] may be 50 or less. [3] In the optical laminate described in [1] or [2] above, the first adhesive sheet has a first main surface in contact with the first liquid crystal layer and a second main surface opposite to the first main surface, and the optical laminate comprises a further layer in contact with the second main surface of the first adhesive sheet, and when the average refractive index of the first adhesive sheet is n, the average refractive index of the first liquid crystal layer is n1, and the average refractive index of the further layer is n2, the absolute value of the value calculated by the formula: {(n1 + n2) / 2 - n} may be 0.08 or less. [4] The optical laminate described in any of [1] to [3] above may further comprise a polarizing film located on the opposite side of the first liquid crystal layer from the first adhesive sheet. [5] The optical laminate described in [4] above may further comprise a second liquid crystal layer located on the opposite side of the first adhesive sheet from the first liquid crystal layer. [6] In the optical laminate described in [5] above, the first liquid crystal layer and the second liquid crystal layer may be joined together via an adhesive. [7] The optical laminate described in [5] or [6] above may further include a second adhesive sheet located on the opposite side of the first liquid crystal layer from the second liquid crystal layer. [8] The optical laminate described in any of [1] to [3] above may further include a second liquid crystal layer located on the opposite side of the first liquid crystal layer from the first adhesive sheet, and the first liquid crystal layer and the second liquid crystal layer may be joined via the first adhesive sheet. [9] The optical laminate described in [8] above may further include a polarizing film located on the opposite side of the first adhesive sheet from the first liquid crystal layer.

[10] The optical laminate described in [8] or [9] above may further include a second adhesive sheet located on the opposite side of the first liquid crystal layer from the second liquid crystal layer.

[11] In the optical laminate described in any of [1] to

[10] above, the first adhesive sheet may include a crosslinked base polymer.

[12] In the optical laminate described in

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

[13] In the optical laminate described in

[11] or

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

[14] In the optical laminate described in

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

[15] In the optical laminate described in

[13] or

[14] above, the content of the aromatic ring-containing monomer in the monomer component may be 60% by weight or more.

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

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

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

[16] above.

[0007] According to embodiments of the present invention, an optical laminate is provided that comprises a liquid crystal layer and an adjacent adhesive sheet, yet is suitable for use in image display devices that may be exposed to extremely low temperature changes.

[0008] This is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. This is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. This is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. This is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. This is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. This is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. This is a schematic plan view of an optical laminate according to one embodiment of the present invention. This is a schematic plan view of an optical laminate according to one embodiment of the present invention. This is a schematic plan view of an optical laminate according to one embodiment of the present invention. This is a schematic plan view of an optical laminate according to one embodiment of the present invention. This is a schematic plan view of an optical laminate according to one embodiment of the present invention. This is a schematic plan view of an optical laminate according to one embodiment of the present invention. This is a schematic cross-sectional view of an image display device according to one embodiment of the present invention.

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

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

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

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

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

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

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

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

[0017] ≪≪1. Optical Laminate≫≫ An optical laminate according to an embodiment of the present invention comprises a first liquid crystal layer and a first adhesive sheet adjacent to the first liquid crystal layer. The glass transition temperature (Tg) of the first adhesive sheet is -10°C or higher. According to the inventors' studies, the liquid crystal layer has a larger coefficient of linear expansion than a general resin film and tends to be brittle against shrinkage stress generated when cooled to an extremely low temperature of about -40°C. It is presumed that having a Tg of -10°C or higher for the first adhesive sheet adjacent to the first liquid crystal layer suppresses the shrinkage of the first liquid crystal layer when cooled to an extremely low temperature, thereby contributing to the suppression of crack generation and their elongation in the first liquid crystal layer.

[0018] The Tg of the first adhesive sheet may be -9°C or higher, -7°C or higher, -5°C or higher, -4°C or higher, -2°C or higher, -1°C or higher, 0°C or higher, 1°C or higher, 2°C or higher, 3°C or higher, 4°C or higher, 5°C or higher, 6°C or higher, 7°C or higher, 8°C or higher, 9°C or higher, and even 10°C or higher. The upper limit of Tg is, for example, 30°C or lower, and may be 25°C or lower, 22°C or lower, 20°C or lower, 19°C or lower, 17°C or lower, 15°C or lower, 14°C or lower, 13°C or lower, 12°C or lower, 11°C or lower, and even 10°C or lower.

[0019] The Tg of the first adhesive sheet is determined by dynamic viscoelasticity measurement. More specifically, the Tg of the first adhesive sheet can be measured as follows: Prepare a measurement sample made of the material constituting the first adhesive sheet. The shape of the measurement sample is disc-shaped. The measurement sample has a base diameter of 8 mm and a thickness of 1 mm. The measurement sample may also be a disc-shaped cutout of a laminate of multiple first adhesive sheets. Next, perform dynamic viscoelasticity measurement on the measurement sample. For dynamic viscoelasticity measurement, for example, TA Instruments' "ARES-G2" can be used. From the results of the dynamic viscoelasticity measurement, the temperature at which the loss tangent (tanδ) is maximum (peak top temperature) can be determined as Tg. The conditions for dynamic viscoelasticity measurement are as follows: Measurement conditions Frequency: 1 Hz Deformation mode: Torsion Measurement temperature: -70°C to 150°C Heating rate: 5°C / min

[0020] The Tg of the first adhesive sheet may be measured as follows. Prepare a measurement sample made of the material constituting the first adhesive sheet. The shape of the measurement sample is a strip with a width of 10 mm, a length of 40 mm, and a thickness of 20 μm. The measurement sample may also be made by punching out a strip from a laminate in which multiple first adhesive sheets are stacked. Next, perform dynamic viscoelasticity measurement on the measurement sample. For dynamic viscoelasticity measurement, for example, TA Instruments' "RSA-G2" can be used. From the results of the dynamic viscoelasticity measurement, the temperature at which the loss tangent (tanδ) is maximum (peak top temperature) can be identified as Tg. The conditions for dynamic viscoelasticity measurement are as follows: Measurement conditions Chuck distance: 15 mm Frequency: 1 Hz Deformation mode: Tensile Measurement temperature: -70°C to 150°C Heating rate: 5°C / min

[0021] Further investigations by the inventors have shown that the small change in the storage modulus of the first adhesive sheet during cooling to extremely low temperatures may be particularly suitable for suppressing the elongation of cracks in the first liquid crystal layer. From the above perspective, the ratio of the storage modulus of the first adhesive sheet G'(-40°C) at -40°C to the storage modulus of the first adhesive sheet G'(-10°C) at -10°C [G'(-40°C) / G'(-10°C)] may be 50 or less, and may be 45 or less, 40 or less, 35 or less, 30 or less, 25 or less, 22 or less, 20 or less, 17 or less, 15 or less, 14 or less, 13 or less, 12 or less, 11 or less, 10 or less, 9 or less, 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, 3 or less, 2.5 or less, 2 or less, 1.5 or less, and even 1.2 or less. The lower limit of the ratio [G'(-40°C) / G'(-10°C)] is, for example, 1.

[0022] Furthermore, the ratio of the storage modulus G'(-40°C) of the first adhesive sheet at -40°C to the storage modulus G'(0°C) of the first adhesive sheet at 0°C [G'(-40°C) / G'(0°C)] may be 150 or less, and may be 140 or less, 130 or less, 120 or less, 110 or less, 100 or less, 90 or less, 80 or less, 70 or less, 60 or less, 50 or less, 45 or less, 40 or less, 35 or less, 30 or less, 25 or less, 20 or less, 19 or less, 17 or less, 15 or less, 14 or less, 12 or less, 10 or less, 9 or less, 7 or less, 5 or less, 4 or less, 3 or less, 2.5 or less, 2 or less, and even 1.5 or less. The lower limit of the ratio [G'(-40°C) / G'(0°C)] is, for example, 1.

[0023] The storage modulus G' (-40°C) of the first adhesive sheet at -40°C is, for example, 375 MPa or more, and may be 400 MPa or more, 425 MPa or more, 450 MPa or more, 475 MPa or more, 500 MPa or more, 525 MPa or more, 550 MPa or more, 575 MPa or more, 600 MPa or more, 625 MPa or more, 650 MPa or more, 675 MPa or more, 700 MPa or more, 725 MPa or more, 750 MPa or more, 775 MPa or more, 800 MPa or more, 825 MPa or more, 850 MPa or more, 875 MPa or more, 900 MPa or more, 925 MPa or more, 950 MPa or more, 975 MPa or more, 1000 MPa or more, 1050 MPa or more, and even 1100 MPa or more. The upper limit of G' (-40°C) is, for example, 2000 MPa or less, but may also be 1900 MPa or less, 1800 MPa or less, 1700 MPa or less, 1600 MPa or less, or even 1500 MPa or less.

[0024] The storage modulus G' (-10°C) of the first adhesive sheet at -10°C is, for example, 200 MPa or more, and may be 225 MPa or more, 250 MPa or more, 275 MPa or more, 300 MPa or more, 325 MPa or more, 350 MPa or more, 375 MPa or more, 400 MPa or more, 425 MPa or more, 450 MPa or more, 475 MPa or more, 500 MPa or more, 525 MPa or more, 550 MPa or more, 575 MPa or more, 600 MPa or more, 625 MPa or more, 650 MPa or more, 675 MPa or more, 700 MPa or more, 725 MPa or more, 750 MPa or more, 775 MPa or more, 800 MPa or more, 850 MPa or more, 900 MPa or more, 950 MPa or more, and even 1000 MPa or more. The upper limit of G' (-10°C) is, for example, 1800 MPa or less, but may also be 1700 MPa or less, 1600 MPa or less, 1500 MPa or less, 1450 MPa or less, or even 1400 MPa or less.

[0025] The storage modulus G'(0°C) of the first adhesive sheet at 0°C is, for example, 1 MPa or more, and may be 5 MPa or more, 10 MPa or more, 30 MPa or more, 50 MPa or more, 100 MPa or more, 150 MPa or more, 200 MPa or more, 250 MPa or more, 300 MPa or more, 350 MPa or more, 400 MPa or more, 450 MPa or more, 500 MPa or more, 550 MPa or more, 600 MPa or more, 650 MPa or more, 700 MPa or more, 750 MPa or more, and even 800 MPa or more. The upper limit of G'(0°C) is, for example, 1500 MPa or less, and may be 1250 MPa or less, 1000 MPa or less, 900 MPa or less, 800 MPa or less, and even 700 MPa or less.

[0026] In one embodiment, which is not limited thereto, the storage modulus G'(85°C) of the first adhesive sheet at 85°C is, for example, 100 kPa or less, and may be 80 kPa or less, 60 kPa or less, 55 kPa or less, 50 kPa or less, 45 kPa or less, 43 kPa or less, 40 kPa or less, 38 kPa or less, and even 35 kPa or less. In this embodiment, the lower limit of the storage modulus G'(85°C) is, for example, 10 kPa or more, and may be 15 kPa or more, 20 kPa or more, 25 kPa or more, 28 kPa or more, 30 kPa or more, 33 kPa or more, and even 34 kPa or more. In this embodiment, the storage modulus G'(85°C) is preferably 10 kPa to 100 kPa, and more preferably 30 kPa to 55 kPa.

[0027] In a different embodiment, which is not limited to the above, the storage modulus G'(85°C) of the first adhesive sheet at 85°C is, for example, greater than 0.1 MPa, and may be 0.3 MPa or more, 0.5 MPa or more, 0.7 MPa or more, or even 1 MPa or more. In this embodiment, the upper limit of the storage modulus G'(85°C) is, for example, 10 MPa or less. The optical laminate may further include a polarizing film located on the opposite side of the first liquid crystal layer from the first adhesive sheet, but having the storage modulus G'(85°C) of the first adhesive sheet within the above range may suppress the transmission of shrinkage stress to the first liquid crystal layer when shrinkage occurs in the polarizing film (specifically, the polarizer in the polarizing film) in a high-temperature environment. Note that shrinkage of the first liquid crystal layer in a high-temperature environment may cause changes in the characteristics of the first liquid crystal layer (e.g., phase difference value).

[0028] The storage modulus G' (-40°C), storage modulus G' (-10°C), storage modulus G' (0°C), and storage modulus G' (85°C) can be determined by the dynamic viscoelasticity measurement described above.

[0029] The first adhesive sheet has a first main surface in contact with the first liquid crystal layer and a second main surface opposite to the first main surface. The optical laminate according to an embodiment of the present invention may include a further layer in contact with the second main surface of the first adhesive sheet. In this case, when the average refractive index of the first adhesive sheet is n, the average refractive index of the first liquid crystal layer is n1, and the average refractive index of the further layer is n2, the absolute value of the value calculated by the formula {(n1 + n2) / 2 - n} may be 0.08 or less, 0.07 or less, 0.06 or less, 0.05 or less, 0.04 or less, 0.03 or less, 0.02 or less, and even 0.01 or less. The lower limit of the above absolute value may be 0. Having the above absolute value of 0.08 or less can contribute to suppressing the occurrence of display unevenness in an image display device to which the optical laminate is applied. Examples of further layers include the polarizing film 3 (if the polarizing film 3 is multilayered, the layer included in the polarizing film 3 that is closest to the first liquid crystal layer, for example, the protective film) and the second liquid crystal layer 4, which will be described later.

[0030] The average refractive indices n and n2 (excluding n2, which is the average refractive index of the liquid crystal layer) can be measured using an Abbe refractometer under the conditions of a measurement temperature of 25°C and a measurement wavelength of 589 nm.

[0031] The average refractive indices n1 and n2 (n2 being the average refractive index of the liquid crystal layer) can be calculated from the average refractive index in the transmission axis direction, Re(550) and Rth(550) of the liquid crystal layer. Specifically, it is as follows. Note that Re(550) and Rth(550) of the liquid crystal layer can be measured using a phase difference measuring device (for example, Axometers, Axoscan series). ・Calculate nx, ny, and nz from the following system of equations. Re(550) = (nx - ny) × d Nz = Rth(550) / Re(550) = (nx - nz) / (nx - ny) Next, in the equation of the ellipse (x² / a²) + (y² / b²) = 1, let a be nx and b be ny, and let x and y be the refractive indices in the x and y directions at the angle θ on the ellipse. Solve the simultaneous equations from y = tanθ and the above nx and ny to calculate the average refractive indices n1 and n2 in the transmission axis direction.

[0032] ≪1-1. Overall Configuration of the Optical Laminate≫ Figure 1 is a schematic cross-sectional view showing an example of an optical laminate according to an embodiment of the present invention. The optical laminate 10 (10A) shown in Figure 1 comprises a first liquid crystal layer 1 and a first adhesive sheet 2. The first liquid crystal layer 1 and the first adhesive sheet 2 are adjacent to each other. In other words, the first liquid crystal layer 1 is bonded to the first adhesive sheet 2. The optical laminate 10 may be used such that the first adhesive sheet 2 is on the viewing side of the first liquid crystal layer 1, or the first liquid crystal layer 1 is on the viewing side of the first adhesive sheet 2. In other words, the first adhesive sheet 2 may be located on the viewing side of the first liquid crystal layer 1, or the first liquid crystal layer 1 may be located on the viewing side of the first adhesive sheet 2.

[0033] The optical laminate 10 according to an embodiment of the present invention may further include other layers besides the first liquid crystal layer 1 and the first adhesive sheet 2, as long as it includes the first liquid crystal layer 1 and the first adhesive sheet 2 adjacent to the first liquid crystal layer 1.

[0034] Fig. 2A is a schematic cross-sectional view showing another example of an optical laminate according to an embodiment of the present invention. The optical laminate 10 (10B) shown in Fig. 2A further comprises a polarizing film 3 located on the opposite side of the first liquid crystal layer 1 with respect to the first pressure-sensitive adhesive sheet 2. The optical laminate 10B comprises the polarizing film 3, the first pressure-sensitive adhesive sheet 2, and the first liquid crystal layer 1 in this order. In the optical laminate 10B, the first pressure-sensitive adhesive sheet 2 is sandwiched between the polarizing film 3 and the first liquid crystal layer 1. In other words, the polarizing film 3 and the first liquid crystal layer 1 are bonded via the first pressure-sensitive adhesive sheet 2. Another layer may be present between the polarizing film 3 and the first pressure-sensitive adhesive sheet 2, but it is preferable that no other layer is present, in other words, the polarizing film 3 and the first pressure-sensitive adhesive sheet 2 are adjacent to each other. The polarizing film 3 is located on the viewing side closer than the first liquid crystal layer 1, for example.

[0035] Fig. 2B is a schematic cross-sectional view showing another example of an optical laminate according to an embodiment of the present invention. The optical laminate 10 (10C) shown in Fig. 2B further comprises a second liquid crystal layer 4 located on the opposite side of the first pressure-sensitive adhesive sheet 2 with respect to the first liquid crystal layer 1. The other configuration is the same as that of the optical laminate 10B shown in Fig. 2A. The optical laminate 10C comprises the polarizing film 3, the first pressure-sensitive adhesive sheet 2, the first liquid crystal layer 1, and the second liquid crystal layer 4 in this order. The first liquid crystal layer 1 and the second liquid crystal layer 4 may be bonded via any pressure-sensitive adhesive sheet disposed between the first liquid crystal layer 1 and the second liquid crystal layer 4, but are preferably bonded via an adhesive. The first liquid crystal layer 1 is located on the viewing side closer than the second liquid crystal layer 4, for example.

[0036] Figure 2C is a schematic cross-sectional view showing another example of an optical laminate according to an embodiment of the present invention. The optical laminate 10 (10D) shown in Figure 2C further comprises a second adhesive sheet 5 located on the opposite side of the first liquid crystal layer 1 from the second liquid crystal layer 4. The other configurations are the same as those of the optical laminate 10C shown in Figure 2B. The optical laminate 10D comprises a polarizing film 3, a first adhesive sheet 2, a first liquid crystal layer 1, a second liquid crystal layer 4, and a second adhesive sheet 5 in this order. Other layers may exist between the second liquid crystal layer 4 and the second adhesive sheet 5, but it is preferable that no other layers exist, in other words, that the second liquid crystal layer 4 and the second adhesive sheet 5 are adjacent to each other. The second adhesive sheet 5 can function, for example, as a panel-side adhesive sheet that allows the optical laminate 10D to be attached to an image display cell.

[0037] The optical laminate 10D may further include a release liner (not shown) placed on the second adhesive sheet 5. When using the optical laminate 10D, for example when attaching it to an image display cell, the release liner may be peeled off.

[0038] Figure 3A is a schematic cross-sectional view showing another example of an optical laminate according to an embodiment of the present invention. The optical laminate 10 (10E) shown in Figure 3A further comprises a second liquid crystal layer 4 located on the opposite side of the first liquid crystal layer 1 from the first adhesive sheet 2. The first liquid crystal layer 1 and the second liquid crystal layer 4 are joined via the first adhesive sheet 2. The optical laminate 10E comprises the first liquid crystal layer 1, the first adhesive sheet 2, and the second liquid crystal layer 4 in this order. In the optical laminate 10E, the first adhesive sheet 2 is sandwiched between the first liquid crystal layer 1 and the second liquid crystal layer 4. In other words, the first liquid crystal layer 1 and the second liquid crystal layer 4 are joined via the first adhesive sheet 2. The first liquid crystal layer 1 is located, for example, on the viewing side of the second liquid crystal layer 4.

[0039] FIG. 3B is a schematic cross-sectional view showing another example of the optical laminate according to an embodiment of the present invention. The optical laminate 10 (10F) shown in FIG. 3B further includes a polarizing film 3 located on the opposite side of the first pressure-sensitive adhesive sheet 2 with respect to the first liquid crystal layer 1. The optical laminate 10F includes the polarizing film 3, the first liquid crystal layer 1, the first pressure-sensitive adhesive sheet 2, and the second liquid crystal layer 4 in this order. The polarizing film 3 and the first liquid crystal layer 1 are bonded to each other via, for example, an adhesive or a pressure-sensitive adhesive. The polarizing film 3 and the first liquid crystal layer 1 may be bonded via any pressure-sensitive adhesive sheet disposed between the polarizing film 3 and the first liquid crystal layer 1. The polarizing film 3 is located closer to the viewing side than the first liquid crystal layer 1, for example. The configuration of the optical laminate 10F is the same as that of the optical laminate 10E shown in FIG. 3A, except that it further includes the polarizing film 3 located on the opposite side of the first pressure-sensitive adhesive sheet 2 with respect to the first liquid crystal layer 1.

[0040] FIG. 3C is a schematic cross-sectional view showing another example of the optical laminate according to an embodiment of the present invention. The optical laminate 10 (10G) shown in FIG. 3C further includes a second pressure-sensitive adhesive sheet 5 located on the opposite side of the first liquid crystal layer 1 with respect to the second liquid crystal layer 4. Other configurations are the same as those of the optical laminate 10F shown in FIG. 3B. The optical laminate 10G includes the polarizing film 3, the first liquid crystal layer 1, the first pressure-sensitive adhesive sheet 2, the second liquid crystal layer 4, and the second pressure-sensitive adhesive sheet 5 in this order. Another layer may be present between the second liquid crystal layer 4 and the second pressure-sensitive adhesive sheet 5, but it is preferable that no other layer is present, in other words, the second liquid crystal layer 4 and the second pressure-sensitive adhesive sheet 5 are adjacent to each other. The second pressure-sensitive adhesive sheet 5 can function, for example, as a panel-side pressure-sensitive adhesive sheet that enables bonding of the optical laminate 10G to an image display cell.

[0041] The optical laminate 10G may further include a release liner (not shown) disposed on the second pressure-sensitive adhesive sheet 5. When the optical laminate 10G is used, for example, when it is bonded to an image display cell, the release liner may be peeled off.

[0042] The optical laminate 10 according to an embodiment of the present invention can have any configuration other than those described above, as long as it includes the first liquid crystal layer 1 and the first pressure-sensitive adhesive sheet 2 adjacent to the first liquid crystal layer 1.

[0043] The components of the optical laminate 10 will be described below.

[0044] ≪1-1. First Liquid Crystal Layer and Second Liquid Crystal Layer≫ The first liquid crystal layer 1 and the second liquid crystal layer 4 may be layers in which liquid crystal compounds are oriented in a predetermined direction within the layer and the orientation state is fixed (hereinafter referred to as the "liquid crystal orientation solidification layer").

[0045] Examples of liquid crystal compounds used in the liquid crystal alignment solidification layer include liquid crystal polymers and liquid crystal monomers. Preferably, the liquid crystal compound is a polymerizable liquid crystal compound, i.e., a liquid crystal monomer. If the liquid crystal compound is polymerizable, the orientation of the liquid crystal compound can be fixed by polymerizing it after orientation. The polymer formed by polymerization may be non-liquid crystallinity. Therefore, the formed liquid crystal alignment solidification layer does not undergo transitions to the liquid crystal phase, glass phase, or crystalline phase due to temperature changes, which are characteristic of liquid crystal compounds. As a result, the liquid crystal alignment solidification layer is unaffected by temperature changes and exhibits excellent stability.

[0046] In one embodiment, the liquid crystal alignment solidified layer may be formed using a liquid crystal composition containing a liquid crystal monomer. In this specification, a liquid crystal monomer contained in a liquid crystal composition means a compound having a polymerizable group and being liquid crystallinity. A polymerizable group means a group that participates in the polymerization reaction, and preferably a photopolymerizable group. Here, a photopolymerizable group means a group that can participate in the polymerization reaction by active radicals or acids generated from a photopolymerization initiator. Examples of such liquid crystal monomers include polymerizable mesogenic compounds described in JP 2002-533742 (WO00 / 37585), EP358208 (US5211877), EP66137 (US4388453), WO93 / 22397, EP0261712, DE19504224, DE4408171, and GB2280445. Examples of such polymerizable mesogenic compounds include BASF's trade name LC242, Merck's trade name E7, and Wacker-Chem's trade name LC-Silicon-CC3767.

[0047] The mechanism by which the liquid crystalline properties of a liquid crystal monomer are manifested may be thermotropic or lyotropic. Furthermore, the liquid crystal phase may be composed of a nematic liquid crystal or a smectic liquid crystal. From the viewpoint of ease of manufacturing, a thermotropic nematic liquid crystal is preferred.

[0048] The temperature range in which liquid crystal monomers exhibit liquid crystalline properties varies depending on the type. Specifically, this temperature range is, for example, 40°C to 120°C, but may also be 50°C to 100°C or 60°C to 90°C.

[0049] The liquid crystal alignment solidification layer may have a phase difference. In other words, at least one layer selected from the group consisting of a first liquid crystal layer 1 and a second liquid crystal layer 4 may be a phase difference layer, and either the first liquid crystal layer 1 or the second liquid crystal layer 4 may be a phase difference layer. A laminated structure including the first liquid crystal layer 1 and the second liquid crystal layer 4 may constitute a phase difference layer. The phase difference layer may include the first liquid crystal layer 1 and the second liquid crystal layer 4 joined to each other via an adhesive, or it may include the first liquid crystal layer 1 and the second liquid crystal layer 4 joined to each other via a first adhesive sheet 2. In this case, the first liquid crystal layer 1 may be located on the viewing side of the second liquid crystal layer 4.

[0050] The birefringence Δn of the liquid crystal alignment solidification layer is, for example, 0.06 or more, may be 0.08 or more, may be 0.09 or more, or may be 0.10 or more. The upper limit of Δn is, for example, 0.13 or less, and may be 0.12 or less. If Δn is within this range, the desired in-plane phase difference can be achieved with a very thin thickness. As a result, it becomes possible to make the liquid crystal alignment solidification layer and the optical laminate thinner, which can, for example, ultimately contribute to a significant reduction in the thinness of the image display device.

[0051] The liquid crystal alignment solidification layer may exhibit inverse dispersion wavelength characteristics in which the phase difference value increases with the wavelength of the measurement light, or it may exhibit positive wavelength dispersion characteristics in which the phase difference value decreases with the wavelength of the measurement light, or it may exhibit flat wavelength dispersion characteristics in which the phase difference value hardly changes with the wavelength of the measurement light.

[0052] The first liquid crystal layer 1 (first liquid crystal alignment solidification layer) and the second liquid crystal layer 4 (second liquid crystal alignment solidification layer), both of which are liquid crystal alignment solidification layers, can typically function as a λ / 2 plate or a λ / 4 plate, respectively. The first liquid crystal alignment solidification layer can typically function as a λ / 2 plate, and the second liquid crystal alignment solidification layer can typically function as a λ / 4 plate.

[0053] Specifically, Re(550) of the first liquid crystal alignment solidification layer is, for example, 150 nm to 300 nm, but may also be 200 nm to 270 nm, or 220 nm to 260 nm.

[0054] Specifically, Re(550) of the second liquid crystal alignment solidification layer is, for example, 100 nm to 200 nm, but may also be 110 nm to 160 nm, or 120 nm to 140 nm.

[0055] The thickness of at least one layer selected from the group consisting of a first liquid crystal alignment solidification layer and a second liquid crystal alignment solidification layer is, for example, 10 μm or less, and may be 8 μm or less, 5 μm or less, 4 μm or less, or even 3 μm or less. The lower limit of the thickness is, for example, 0.5 μm or more, and may be 1 μm or more. The thicknesses of the first liquid crystal alignment solidification layer and the second liquid crystal alignment solidification layer may be the same or different from each other.

[0056] The thickness of the first liquid crystal alignment solidification layer can typically be adjusted to obtain a desired in-plane phase difference of the λ / 2 plate. In one embodiment, the thickness of the first liquid crystal alignment solidification layer is, for example, 0.5 μm to 5.0 μm, but may also be 0.8 μm to 4.0 μm, 1.0 μm to 3.0 μm, 1.2 μm to 2.5 μm, or 1.3 μm to 2.0 μm. In another embodiment, the thickness of the first liquid crystal alignment solidification layer is, for example, 0.3 μm to 1.7 μm, but may also be 0.7 μm to 1.6 μm, 1.0 μm to 1.5 μm, or 1.3 μm to 1.5 μm.

[0057] The thickness of the second liquid crystal alignment solidification layer can typically be adjusted to obtain a desired in-plane phase difference for the λ / 4 plate. In one embodiment, the thickness of the second liquid crystal alignment solidification layer is, for example, 0.5 μm to 2.5 μm, but may also be 0.6 μm to 2.0 μm, 0.7 μm to 1.5 μm, 0.7 μm to 1.2 μm, or 0.7 μm to 1.1 μm.

[0058] When the optical laminate 10 includes a polarizing film 3, the angle between the slow axis of the first liquid crystal alignment solidification layer and the transmission axis of the polarizer contained in the polarizing film 3 is, for example, 10° to 20°, may be 12° to 18°, or 14° to 16°. The angle between the slow axis of the second liquid crystal alignment solidification layer and the transmission axis of the polarizer is, for example, 70° to 80°, may be 72° to 78°, or 74° to 76°. The arrangement order of the first liquid crystal alignment solidification layer and the second liquid crystal alignment solidification layer may be reversed, and the angle between the slow axis of the first liquid crystal alignment solidification layer and the transmission axis of the polarizer and the angle between the slow axis of the second liquid crystal alignment solidification layer and the transmission axis of the polarizer may be reversed.

[0059] The average refractive index of the liquid crystal alignment solidification layer may vary depending on the composition forming the liquid crystal alignment solidification layer (essentially, the type of liquid crystal compound, the type, number, combination, and amount of additives). The average refractive index of the first liquid crystal alignment solidification layer and the average refractive index of the second liquid crystal alignment solidification layer may be the same or different (the average refractive index of the first liquid crystal alignment solidification layer may be higher, or the average refractive index of the second liquid crystal alignment solidification layer may be higher).

[0060] The average refractive index of the first liquid crystal alignment solidification layer is, for example, 1.55 to 1.75, and may also be 1.60 to 1.70.

[0061] The average refractive index of the second liquid crystal alignment solidification layer is, for example, 1.45 to 1.65, and may also be 1.50 to 1.60.

[0062] The average refractive index of the first liquid crystal alignment solidification layer and the average refractive index of the second liquid crystal alignment solidification layer may be reversed from the above. The absolute value of the difference between the average refractive index of the first liquid crystal alignment solidification layer and the average refractive index of the second liquid crystal alignment solidification layer may be, for example, 0.00 to 0.20. The average refractive index of the liquid crystal alignment solidification layer will typically correspond to the composition of the composition in which the liquid crystal alignment solidification layer is formed in order to obtain the desired optical properties.

[0063] A side-chain type thermotropic liquid crystal polymer may be introduced into the first liquid crystal alignment solidification layer and / or the second liquid crystal alignment solidification layer (substantially, the liquid crystal composition forming them). By introducing a side-chain type thermotropic liquid crystal polymer, the effect of homeotropic alignment (vertical alignment) of the liquid crystal monomer can be produced. As a result, the nz of the first liquid crystal alignment solidification layer and / or the second liquid crystal alignment solidification layer can be increased, and as a result, the Nz coefficient of the first liquid crystal alignment solidification layer and / or the second liquid crystal alignment solidification layer can be appropriately adjusted, and ultimately, for example, the Nz coefficient of the phase difference layer can be set to a range of, for example, 0.30 to 0.70 without providing a positive C plate.

[0064] Typical examples of side-chain type thermotropic liquid crystal polymers include copolymers having monomer units containing thermotropic liquid crystal fragment side chains and monomer units containing non-liquivalent fragment side chains. Because the polymer has thermotropic liquid crystal fragments in its side chains, the side-chain type liquid crystal polymer can be oriented when a liquid crystal composition containing liquid crystal monomers is heated to a predetermined temperature. Furthermore, because the side-chain type polymer has non-liquivalent fragments in its side chains, these non-liquivalent fragments can interact with photopolymerizable liquid crystal monomers, resulting in homeotropic orientation of the photopolymerizable liquid crystal monomers.

[0065] As the side-chain type thermotropic liquid crystal polymer, a copolymer having a liquid crystalline monomer unit represented by general formula (I) and a non-liquid crystalline monomer unit represented by general formula (II) is preferably used.

[0066] In equation (I), R 1 R is a hydrogen atom or a methyl group,2 X is a cyano group, a fluoro group, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. 1 is -CO2- or -OCO-. a is an integer from 1 to 6, and b and c are independently 1 or 2.

[0067] In equation (II), R 3 R is a hydrogen atom or a methyl group, 4 This 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).

[0068] In equation (III), R 5 is an alkyl group having 1 to 5 carbon atoms, and d is an integer from 1 to 6.

[0069] The ratio of liquid crystalline monomer units to non-liquid crystalline monomer units in side-chain liquid crystal monomers can be appropriately set depending on the purpose. The ratio (molar ratio) of non-liquid crystalline monomers to the total of liquid crystalline monomer units is, for example, 0.05 to 0.80, but may also be 0.10 to 0.60 or 0.15 to 0.50.

[0070] The ratio of liquid crystal monomer to side-chain liquid crystal polymer in the liquid crystal composition can be appropriately set depending on the purpose. The liquid crystal monomer content may be, for example, 1.2 to 20 times, 1.3 to 10 times, 1.4 to 9 times, or 1.5 to 8 times the content of the side-chain liquid crystal polymer.

[0071] A method for forming a side-chain type liquid crystal polymer and a liquid crystal alignment solidification layer is described, for example, in Japanese Patent No. 6769921, which may be incorporated herein by reference.

[0072] Any suitable adhesive can be used to bond the first liquid crystal layer 1 and the second liquid crystal layer 4, as long as it does not impair the effects of the present invention. UV-curing adhesives or water-based adhesives are preferred. Examples of water-based adhesives include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl latex-based adhesives, water-based polyurethanes, and water-based polyesters. In addition to the above, electron beam-curing adhesives and the like can also be used as the adhesive layer. The adhesive layer may contain metal compound fillers.

[0073] The surface of at least one layer selected from the group consisting of the first liquid crystal layer 1 and the second liquid crystal layer 4 may be surface-treated. An example of surface treatment is an easy-adhesion treatment. The easy-adhesion treatment can be carried out by physical treatment such as corona treatment or plasma treatment, or by chemical treatment such as primer treatment. For example, the surface of the first liquid crystal layer 1 that is in contact with the first adhesive sheet 2 may be surface-treated.

[0074] ≪1-2. First Adhesive Sheet≫ The first adhesive sheet 2 is usually composed of an adhesive. The first adhesive sheet 2 may contain a crosslinked base polymer and is typically formed by curing an adhesive composition containing a base polymer.

[0075] <1-2-1. Adhesive Composition> (1-2-1-a. Base Polymer) The base polymer contained in the adhesive composition may be a (meth)acrylic polymer. In this case, the first adhesive sheet 2 will be a (meth)acrylic adhesive sheet. A (meth)acrylic polymer means a polymer in which the main constituent unit of the base polymer is a (meth)acrylate unit. The main constituent unit means the constituent unit that has the largest weight percentage among all constituent units of the base polymer. The weight percentage of the main constituent unit may be, for example, 50% or more, 60% or more, 65% or more, 70% or more, 75% or more, 80% or more, 85% or more, 90% or more, and even 92% or more. The upper limit of this percentage may be, for example, 100% or less, and 99% or less.

[0076] The polymer structure of the base polymer may be any of the following: random copolymer structure, block copolymer structure, graft copolymer structure, etc. The base polymer is obtained by polymerization of monomer components.

[0077] The monomer component preferably includes an aromatic ring-containing monomer. The aromatic ring-containing monomer may be one type or two or more types.

[0078] As aromatic ring-containing monomers, compounds containing at least one aromatic ring and at least one ethylenically unsaturated group in one molecule can be used.

[0079] Examples of ethylenically unsaturated groups include (meth)acryloyl groups, vinyl groups, and (meth)allyl groups. (Meth)acryloyl groups are preferred as the ethylenically unsaturated group, and acryloyl groups are more preferred. Therefore, a preferred embodiment of the aromatic ring-containing monomer is an aromatic ring-containing (meth)acrylate.

[0080] From the viewpoint of suppressing a decrease in the flexibility of the adhesive, a compound having one ethylenically unsaturated group in one molecule (i.e., a monofunctional monomer) is preferred as the aromatic ring-containing monomer.

[0081] The number of aromatic rings contained in one molecule of aromatic ring-containing monomer is, for example, 1 to 16, but may also be 2 to 12, 2 to 8, 2 to 6, 2 to 4, 2 to 3, or 2.

[0082] The aromatic ring contained in the aromatic ring-containing monomer may be a hydrocarbon ring such as a benzene ring (which may be a benzene ring that constitutes part of a biphenyl or fluorene structure); a condensed ring of a naphthalene ring, indene ring, azulene ring, anthracene ring, or phenanthrene ring; or a heterocycle such as a pyridine ring, pyrimidine ring, pyridazine ring, pyrazine ring, triazine ring, pyrrole ring, pyrazole ring, imidazole ring, triazole ring, oxazole ring, isoxazole ring, thiazole ring, or thiophene ring. Examples of heteroatoms contained in such heterocycles include nitrogen, sulfur, and oxygen, with nitrogen and sulfur being preferred. The aromatic ring-containing monomer may have a structure in which one or more carbon rings and one or more heterocycles are fused, such as a dinaphthothiophene structure.

[0083] The aromatic ring contained in the aromatic ring-containing monomer may have substituents on its ring constituent atoms. There may be only one substituent or two or more substituents. Examples of substituents include alkyl groups, alkoxy groups, aryloxy groups, hydroxyl groups, halogen atoms, hydroxyalkyl groups, hydroxyalkyloxy groups, and glycidyloxy groups.

[0084] The aromatic ring and the ethylenically unsaturated group contained in the aromatic ring-containing monomer may be directly bonded or may be bonded via a linking group. Examples of such a linking group include an alkylene group, an oxyalkylene group, a poly(oxyalkylene) group, a phenyl group, an alkylphenyl group, an alkoxyphenyl group, and a group having a structure in which one or two or more hydrogen atoms in these groups are substituted with a hydroxyl group (e.g., a hydroxyalkylene group), an oxy group (-O- group), and a thiooxy group (-S- group), and the linking group may be a group comprising at least one structure selected from the group consisting of the foregoing. Preferred examples of such a linking group include a group comprising at least one structure selected from the group consisting of an alkylene group, an oxyalkylene group, and a poly(oxyalkylene) group. The number of carbon atoms in the alkylene group and the oxyalkylene group is preferably 1 to 4, more preferably 1 to 3, and still more preferably 1 to 2. The number of repetitions of oxyalkylene units in the poly(oxyalkylene) group is preferably 2 to 3.

[0085] The aromatic ring-containing monomer may include a monomer having two or more aromatic rings in one molecule (hereinafter may be referred to as "multiple aromatic ring-containing monomer"). Examples of the multiple aromatic ring-containing monomer include a monomer having a structure in which two or more non-fused aromatic rings are bonded via a linking group, a monomer having a structure in which two or more non-fused aromatic rings are directly chemically bonded, a monomer having a fused aromatic ring structure, a monomer having a fluorene structure, a monomer having a dinaphthothiophene structure, and a monomer having a dibenzothiophene structure.

[0086] Examples of the linking group that can be included in the multiple aromatic ring-containing monomer include an oxy group (-O-), a thiooxy group (-S-), an oxyalkylene group (-O-(CH2) n - group, wherein n is 1 to 3, preferably 1), a thiooxyalkylene group (-S-(CH2) n - group, wherein n is 1 to 3, preferably 1), a linear alkylene group (-(CH2) n- Groups, where n is 1 to 6, preferably 1 to 3), oxyalkylene groups, thiooxyalkylene groups, and linear alkylene groups in which the alkylene group is partially halogenated or fully halogenated are examples.

[0087] Examples of monomers having a structure in which two or more non-condensed aromatic rings are linked via linking groups include phenoxybenzyl (meth)acrylate (e.g., m-phenoxybenzyl (meth)acrylate), thiophenoxybenzyl (meth)acrylate, and benzylbenzyl (meth)acrylate.

[0088] Examples of monomers having a structure in which two or more non-condensed aromatic rings are directly chemically bonded include biphenyl structure-containing (meth)acrylates, triphenyl structure-containing (meth)acrylates, and vinyl group-containing biphenyls. Specific examples include o-phenylphenol (meth)acrylate and biphenylmethyl (meth)acrylate.

[0089] Examples of monomers having a condensed aromatic ring structure include naphthalene ring-containing (meth)acrylate, anthracene ring-containing (meth)acrylate, vinyl group-containing naphthalene, and vinyl group-containing anthracene. Specific examples include 1-naphthylmethyl (meth)acrylate (also known as 1-naphthalenemethyl (meth)acrylate), hydroxyethylated β-naphthol acrylate, 2-naphthoethyl (meth)acrylate, 2-naphthoxyethyl acrylate, and 2-(4-methoxy-1-naphthoxy)ethyl (meth)acrylate.

[0090] Examples of monomers having a fluorene structure include 9,9-bis(4-hydroxyphenyl)fluorene (meth)acrylate and 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene (meth)acrylate. It should be noted that monomers having a fluorene structure include a structural portion in which two benzene rings are directly chemically bonded, and therefore can be included in the concept of monomers having a structure in which two or more non-condensed aromatic rings are directly chemically bonded.

[0091] Examples of monomers having a dinaphthothiophene structure include (meth)acryloyl group-containing dinaphthothiophene, vinyl group-containing dinaphthothiophene, and (meth)allyl group-containing dinaphthothiophene. A specific example is (meth)acryloyloxymethyl dinaphthothiophene (for example, CH2CH(R) at the 5th or 6th position of the dinaphthothiophene ring). 1 ) Compounds with a structure in which C(O)OCH2- is bonded, R 1 (R) is a hydrogen atom or a methyl group. ) (meth)acryloyloxyethyl dinaphthothiophene (for example, CH2CH(R) at the 5th or 6th position of the dinaphthothiophene ring) 1 )C(O)OCH(CH3)- or CH2CH(R 1 Compounds with a structure in which C(O)OCH2CH2- is bonded, R 1 The group is a hydrogen atom or a methyl group. Examples include vinyl dinaphthothiophene (for example, a compound in which a vinyl group is bonded to the 5th or 6th position of the naphthothiophene ring) and (meth)allyloxydinaphthothiophene. Note that monomers having a dinaphthothiophene structure can also be included in the concept of monomers having a condensed aromatic ring structure by including a naphthalene structure or by having a structure in which a thiophene ring and two naphthalene structures are condensed.

[0092] Examples of monomers having a dibenzothiophene structure include (meth)acryloyl group-containing dibenzothiophene and vinyl group-containing dibenzothiophene. Since monomers having a dibenzothiophene structure have a structure in which a thiophene ring and two benzene rings are condensed, they can be included in the concept of monomers having a condensed aromatic ring structure. Neither the dinaphthothiophene structure nor the dibenzothiophene structure corresponds to a structure in which two or more non-condensed aromatic rings are directly chemically bonded.

[0093] As the aromatic ring-containing monomer, a monomer having one aromatic ring in one molecule may be used. Monomers having one aromatic ring in one molecule can be useful, for example, for adjusting the adhesive properties of adhesives and improving transparency.

[0094] Examples of monomers having one aromatic ring in one molecule include carbon aromatic ring-containing (meth)acrylates such as benzyl (meth)acrylate, methoxybenzyl (meth)acrylate, phenyl (meth)acrylate, ethoxylated phenol (meth)acrylate, phenoxypropyl (meth)acrylate, phenoxybutyl (meth)acrylate, cresyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, chlorobenzyl (meth)acrylate, etc.; 2-(4,6-dibromo-2-s-butylphenoxy)ethyl (meth)acrylate, 2-(4,6-dibromo-2-isopropylphenoxy)ethyl (meth)acrylate, Examples include bromine-substituted aromatic ring-containing (meth)acrylates such as 6-(4,6-dibromo-2-s-butylphenoxy)hexyl (meth)acrylate, 6-(4,6-dibromo-2-isopropylphenoxy)hexyl (meth)acrylate, 2,6-dibromo-4-nonylphenyl acrylate, and 2,6-dibromo-4-dodecylphenyl acrylate; carbon aromatic ring-containing vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, and tert-butylstyrene; and compounds having vinyl substituents on heteroaromatic rings such as N-vinylpyridine, N-vinylpyrimidine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, and N-vinyloxazole.

[0095] Among the above, preferred aromatic ring-containing monomers include phenoxybenzyl (meth)acrylate, 1-naphthylmethyl (meth)acrylate, ethoxylated o-phenylphenol (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, 6-(meth)acryloyloxymethyl dinaphthothiophene, 5-(meth)acryloyloxyethyl dinaphthothiophene, 6-(meth)acryloyloxyethyl dinaphthothiophene, 6-vinyl dinaphthothiophene, and 5-vinyl dinaphthothiophene. The aromatic ring-containing monomer preferably contains phenoxybenzyl (meth)acrylate, and more preferably contains phenoxybenzyl acrylate.

[0096] The content of aromatic ring-containing monomers in the monomer component is, for example, 10% by weight or more, and may be 20% by weight or more, 30% by weight or more, 40% by weight or more, 50% by weight or more, 55% by weight or more, 60% by weight or more, 65% by weight or more, 68% by weight or more, 70% by weight or more, 73% by weight or more, 75% by weight or more, 78% by weight or more, 80% by weight or more, 83% by weight or more, 85% by weight or more, 87% by weight or more, 89% by weight or more, and even 90% by weight or more. The above content is, for example, 99% by weight or less, and may be 98% by weight or less, 95% by weight or less, 93% by weight or less, 90% by weight or less, 88% by weight or less, 85% by weight or less, 83% by weight or less, 80% by weight or less, 78% by weight or less, 75% by weight or less, 73% by weight or less, 70% by weight or less, 68% by weight or less, and even 65% by weight or less. The monomer component does not need to contain aromatic ring-containing monomers.

[0097] The monomer component may include a non-aromatic ring-containing monomer. In this case, the monomer component may or may not include an aromatic ring-containing monomer. There may be only one non-aromatic ring-containing monomer or two or more non-aromatic ring-containing monomers.

[0098] Non-aromatic ring-containing monomers are compounds that contain a non-aromatic ring in their structure and also contain polymerizable unsaturated double bonds such as (meth)acryloyl groups and vinyl groups. Non-aromatic ring-containing monomers may also be non-aromatic ring-containing (meth)acrylates.

[0099] Examples of non-aromatic rings include non-aromatic aliphatic rings (non-aromatic alicyclic rings) [e.g., cycloalkane rings such as cyclopentane, cyclohexane, cycloheptane, and cyclooctane rings; cycloalkene rings such as cyclohexene rings, etc.], non-aromatic bridged rings [e.g., bicyclic hydrocarbon rings in pinane, pinene, bornane, isobornyl, norbornane, norbornene, etc.; triplicate or more aliphatic hydrocarbon rings (bridged hydrocarbon rings) in adamantane, etc.], and non-aromatic heterocycles [e.g., epoxy rings, oxolane rings, oxetane rings, etc.].

[0100] Examples of the above-mentioned aliphatic hydrocarbon rings with three or more rings (cross-linked hydrocarbon rings with three or more rings) include dicyclopentanyl group, dicyclopentenyl group, adamantyl group, tricyclopentanyl group, and tricyclopentenyl group.

[0101] Examples of non-aromatic ring-containing (meth)acrylates include cycloalkyl (meth)acrylates such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, and cyclooctyl (meth)acrylate; (meth)acrylates having a bicyclic aliphatic hydrocarbon ring such as isobornyl (meth)acrylate; and (meth)acrylates having three or more aliphatic hydrocarbon rings such as dicyclopentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, tricyclopentanyl (meth)acrylate, 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, and 2-ethyl-2-adamantyl (meth)acrylate. Non-aromatic ring-containing (meth)acrylates may be used alone or in combination of two or more types.

[0102] The content of non-aromatic ring-containing monomers in the monomer component is, for example, 10% by weight or more, and may be 20% by weight or more, 30% by weight or more, 40% by weight or more, 50% by weight or more, 55% by weight or more, 60% by weight or more, 65% by weight or more, 68% by weight or more, 70% by weight or more, 73% by weight or more, 75% by weight or more, 78% by weight or more, 80% by weight or more, 83% by weight or more, 85% by weight or more, 87% by weight or more, 89% by weight or more, and even 90% by weight or more. The above content is, for example, 99% by weight or less, and may be 98% by weight or less, 95% by weight or less, 93% by weight or less, 90% by weight or less, 88% by weight or less, 85% by weight or less, 83% by weight or less, 80% by weight or less, 78% by weight or less, 75% by weight or less, 73% by weight or less, 70% by weight or less, 68% by weight or less, and even 65% by weight or less. The monomer component does not need to contain non-aromatic ring-containing monomers.

[0103] The monomer component may include monomers copolymerizable with aromatic ring-containing monomers and / or non-aromatic ring-containing monomers (hereinafter sometimes referred to as "copolymer monomers"). There may be only one copolymer monomer or two or more copolymer monomers. Examples of copolymer monomers include alkyl (meth)acrylates, hydroxyl group-containing monomers, carboxyl group-containing monomers, amide group-containing monomers, and the like.

[0104] The number of carbon atoms in the alkyl group in alkyl (meth)acrylate is, for example, 1 to 30. The alkyl group may be linear, branched, or cyclic. Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl, hexyl, cyclohexyl, heptyl, 2-ethylhexyl, isooctyl, nonyl, decyl, isodecyl, dodecyl, isomyristyl, lauryl, tridecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl groups. There may be only one alkyl (meth)acrylate or two or more alkyl (meth)acrylates. Butyl acrylate is preferred as the alkyl (meth)acrylate.

[0105] The content of alkyl (meth)acrylate in the monomer component may be, for example, 70% by weight or less, and may be 60% by weight or less, 50% by weight or less, 45% by weight or less, 40% by weight or less, 35% by weight or less, 30% by weight or less, 25% by weight or less, 22% by weight or less, 20% by weight or less, 17% by weight or less, 15% by weight or less, 14% by weight or less, 13% by weight or less, 12% by weight or less, 11% by weight or less, and even 10% by weight or less. The above content may be, for example, 1% by weight or more, 2% by weight or more, 3% by weight or more, 4% by weight or more, and even 5% by weight or more. The monomer component does not have to contain alkyl (meth)acrylate.

[0106] Hydroxyl group-containing monomers are compounds that contain a hydroxyl group in their structure and also contain a polymerizable unsaturated double bond such as a (meth)acryloyl group or a vinyl group. Hydroxyl group-containing monomers may also be hydroxyl group-containing (meth)acrylates. Examples of hydroxyl group-containing (meth)acrylates include hydroxyl group-containing alkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate; and hydroxyl group-containing cycloalkyl (meth)acrylates such as (4-hydroxymethylcyclohexyl)-methyl acrylate. Among these, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred.

[0107] The content of hydroxyl group-containing monomers in the monomer component is, for example, 0.1% by weight or more, and may be 0.2% by weight or more, 0.4% by weight or more, 0.5% by weight or more, 0.6% by weight or more, 0.8% by weight or more, and even 1% by weight or more. The above content is, for example, 10% by weight or less, and may be 7% by weight or less, 5% by weight or less, 4% by weight or less, 3% by weight or less, 2.5% by weight or less, 2% by weight or less, 1.5% by weight or less, and even 1% by weight or less. The monomer component does not have to contain hydroxyl group-containing monomers.

[0108] A carboxyl group-containing monomer is a compound that contains a carboxyl group in its structure and also contains a polymerizable unsaturated double bond such as a (meth)acryloyl group or a vinyl group. A carboxyl group-containing monomer may also be a carboxyl group-containing (meth)acrylate. Examples of carboxyl group-containing (meth)acrylates include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid.

[0109] The content of carboxyl group-containing monomers in the monomer component may be, for example, 10% by weight or less, and may be 7% by weight or less, 5% by weight or less, 3% by weight or less, 2% by weight or less, or even 1% by weight or less. The above content may be, for example, 0.1% by weight or more, and may be 0.5% by weight or more. The monomer component does not have to contain carboxyl group-containing monomers.

[0110] Amide group-containing monomers are compounds that contain an amide group in their structure and also contain polymerizable unsaturated double bonds such as (meth)acryloyl groups and vinyl groups. Amide group-containing monomers may also be amide group-containing (meth)acrylates. Examples of amide group-containing (meth)acrylates include acrylamide monomers such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropylacrylamide, N-methyl(meth)acrylamide, N-butyl(meth)acrylamide, N-hexyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methylol-N-propane(meth)acrylamide, aminomethyl(meth)acrylamide, aminoethyl(meth)acrylamide, mercaptomethyl(meth)acrylamide, and mercaptoethyl(meth)acrylamide; N-acryloyl heterocyclic monomers such as N-(meth)acryloylmorpholin, N-(meth)acryloylpiperidine, and N-(meth)acryloylpyrrolidine; and N-vinyl group-containing lactam monomers such as N-vinylpyrrolidone and N-vinyl-ε-caprolactam.

[0111] The content of amide group-containing monomers in the monomer component may be, for example, 10% by weight or less, 7% by weight or less, 5% by weight or less, or even 3% by weight or less. The above content may be, for example, 0.1% by weight or more, or 0.5% by weight or more. The monomer component does not have to contain amide group-containing monomers.

[0112] In one embodiment, which is not limited thereto, the content of the amide group-containing monomer in the monomer component may be 10% by weight or more, 20% by weight or more, 30% by weight or more, 40% by weight or more, 50% by weight or more, and even 60% by weight or more. In this embodiment, the upper limit of the above content is 90% by weight or less.

[0113] In addition to the above, copolymer monomers include, for example, acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride; caprolactone adducts of acrylic acid; sulfonic acid group-containing monomers such as allyl sulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidepropanesulfonic acid, and sulfopropyl (meth)acrylate; phosphate group-containing monomers such as 2-hydroxyethyl acryloyl phosphate; aminoethyl (meth)acrylate and N,N-dimethylaminoethyl (meth)acrylate. Alkylaminoalkyl (meth)acrylates such as t-butylaminoethyl (meth)acrylate; alkoxyalkyl (meth)acrylates such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate; succinimide monomers such as N-(meth)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, and N-(meth)acryloyl-8-oxyoctamethylenesuccinimide; N-cyclohexylmaleimide, N-isopropyl Maleimide monomers such as maleimide, N-laurylmaleimide, and N-phenylmaleimide; itaconimide monomers such as N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, and N-laurylitaconimide; vinyl monomers such as vinyl acetate and vinyl propionate; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; glycidyl (meth)acrylate Epoxy group-containing (meth)acrylates such as; glycol-based (meth)acrylates such as carbitol (meth)acrylate, ethyl carbitol (meth)acrylate, polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, etc.; (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, silicone (meth)acrylate, etc.Examples of silane monomers containing silicon atoms include 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8-vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, and 10-acryloyloxydecyltriethoxysilane.

[0114] The content of other copolymer monomers in the monomer component may be, for example, 5% by weight or less, 3% by weight or less, or even 1% by weight or less. The monomer component may not contain other copolymer monomers.

[0115] The base polymer is obtained by polymerizing monomer components. The base polymer can be formed by various known polymerization methods, such as solution polymerization, radiation polymerization using electron beams or ultraviolet (UV) light, bulk polymerization, and emulsion polymerization. Polymerization is typically radical polymerization.

[0116] For solution polymerization, known polymerization solvents such as ethyl acetate and toluene can be used as the polymerization solvent. Solution polymerization can be carried out, for example, using a polymerization initiator and under an inert gas stream such as nitrogen. Any suitable polymerization conditions can be adopted as long as they do not impair the effects of the present invention. Such polymerization conditions include, for example, a polymerization temperature of 50°C to 70°C and a polymerization time of 5 to 30 hours.

[0117] Any suitable compound can be used as a polymerization initiator, chain transfer agent, or emulsifier for radical polymerization, as long as it does not impair the effects of the present invention.

[0118] Examples of polymerization initiators include azo-based initiators such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-amidinopropane)dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane]dihydrochloride, 2,2'-azobis(2-methylpropionamidine)disulfate, 2,2'-azobis(N,N'-dimethyleneisobutylamidine), and 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]hydrate (e.g., VA-057 manufactured by Wako Pure Chemical Industries, Ltd.); persulfates such as potassium persulfate and ammonium persulfate; di(2-ethylhexyl)peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, di- Examples of peroxide initiators include sec-butyl peroxydicarbonate, t-butyl peroxyneodecanoate, t-hexyl peroxypivalate, t-butyl peroxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, di(4-methylbenzoyl) peroxide, dibenzoyl peroxide, t-butyl peroxyisobutyrate, 1,1-di(t-hexyl peroxy)cyclohexane, t-butyl hydroperoxide, and hydrogen peroxide; and redox initiators combining peroxides and reducing agents, such as combinations of persulfates and sodium bisulfite, or combinations of peroxides and sodium ascorbate. The polymerization initiator may be one type or two or more types. The amount of polymerization initiator used can be any appropriate amount, as long as it does not impair the effects of the present invention. Such usage amounts are, for example, 0.005 parts by weight to 1 part by weight, or 0.02 parts by weight to 0.5 parts by weight, per 100 parts by weight of the monomer component.

[0119] Examples of chain transfer agents include lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, and 2,3-dimercapto-1-propanol. The chain transfer agent may be used alone or in combination of two or more. The amount of chain transfer agent used can be any appropriate amount, as long as it does not impair the effects of the present invention. For example, such an amount is 0.1 parts by weight or less per 100 parts by weight of the monomer component.

[0120] In radiation polymerization, a base polymer is formed by irradiating monomer components with radiation such as electron beams or ultraviolet (UV) light to promote polymerization. When radiation polymerization is performed using electron beams, the use of a photoinitiator is not particularly necessary. When radiation polymerization is performed using UV light, a photoinitiator may be used due to advantages such as shortening the polymerization time. One type of photoinitiator may be used, or two or more types may be used.

[0121] Examples of photopolymerization initiators include benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, and thioxanthone-based photopolymerization initiators. The amount of photopolymerization initiator used can be any appropriate amount within a range that does not impair the effects of the present invention. Such an amount may be, for example, 0.05 to 1.5 parts by weight, or 0.1 to 1 part by weight, per 100 parts by weight of the monomer component.

[0122] (1-2-1-b. Crosslinking agent) The adhesive composition may contain a crosslinking agent. There may be only one type of crosslinking agent, or there may be two or more types.

[0123] Examples of crosslinking agents that the adhesive composition may contain include isocyanate-based crosslinking agents, peroxide-based crosslinking agents, epoxy-based crosslinking agents, imine-based crosslinking agents, and polyfunctional metal chelates. The adhesive composition preferably contains an isocyanate-based crosslinking agent and / or a peroxide-based crosslinking agent, and more preferably contains an isocyanate-based crosslinking agent.

[0124] As an isocyanate crosslinking agent, a compound having at least two isocyanate groups (isocyanate compound) can be used. Preferably, the number of isocyanate groups in the isocyanate compound is three or more. The upper limit of the number of isocyanate groups is not particularly limited, but is, for example, five. Examples of isocyanate compounds include aromatic isocyanate compounds, alicyclic isocyanate compounds, and aliphatic isocyanate compounds.

[0125] Examples of aromatic isocyanate compounds include phenylenediisocyanate, 2,4-tolylenediisocyanate, 2,6-tolylenediisocyanate, 2,2'-diphenylmethanediisocyanate, 4,4'-diphenylmethanediisocyanate, 4,4'-toluidinediisocyanate, 4,4'-diphenyletherdiisocyanate, 4,4'-diphenyldiisocyanate, 1,5-naphthalenediisocyanate, and xylylenediisocyanate.

[0126] Examples of alicyclic isocyanate compounds include 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated tetramethylxylylene diisocyanate.

[0127] Examples of aliphatic isocyanate compounds include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

[0128] Examples of isocyanate-based crosslinking agents include polymers (dimers, trimers, pentamers, etc.) of the above-mentioned isocyanate compounds, adducts obtained by adding them to polyhydric alcohols such as trimethylolpropane, urea-modified compounds, biuret-modified compounds, allophanate-modified compounds, isocyanurate-modified compounds, carbodiimide-modified compounds, polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, polyisoprene polyols, and urethane prepolymers obtained by adding them to these materials.

[0129] The isocyanate crosslinking agent is preferably an aromatic isocyanate compound and its derivatives, more preferably tolylene diisocyanate and its derivatives, in other words, a tolylene diisocyanate-based (TDI) crosslinking agent. From the viewpoint of reactivity, TDI crosslinking agents are more suitable than xylylene diisocyanate and its derivatives, in other words, xylylene diisocyanate-based (XDI) crosslinking agents. The isocyanate crosslinking agent may also contain polyhydric alcohols and adducts of tolylene diisocyanate as TDI crosslinking agents. A specific example of an adduct is a trimethylolpropane / tolylene diisocyanate trimer adduct.

[0130] Commercially available isocyanate crosslinking agents may be used. Examples of such commercially available products include Millionate MT, Millionate MTL, Millionate MR-200, Millionate MR-400, Coronate HL, Coronate HX (all manufactured by Tosoh Corporation), Takenate D-101E, Takenate D-110N, Takenate D-120N, Takenate D-140N, Takenate D-160N, Takenate D-165N, Takenate D-170HN, Takenate D-178N, Takenate 500, and Takenate 600 (all manufactured by Mitsui Chemicals). Among these, Takenate D-101E and Takenate D-110N are preferred.

[0131] The content of isocyanate-based crosslinking agent in the adhesive composition is, for example, 0.01 to 20 parts by weight per 100 parts by weight of the base polymer. The above content may be 0.05 parts by weight or more, 0.10 parts by weight or more, 0.15 parts by weight or more, 0.20 parts by weight or more, 0.25 parts by weight or more, and even 0.30 parts by weight or more. The above content may be 15 parts by weight or less, 13 parts by weight or less, 10 parts by weight or less, 8 parts by weight or less, 5 parts by weight or less, 3 parts by weight or less, 2 parts by weight or less, 1 part by weight or less, and even 0.5 parts by weight or less. The above content may be 0.03 to 1 part by weight, and even 0.05 to 0.5 parts by weight.

[0132] The content of crosslinking agents other than isocyanate-based crosslinking agents (e.g., peroxide-based crosslinking agents) in the adhesive composition is, for example, 2 parts by weight or less, 1 part by weight or less, and even 0.5 parts by weight or less, per 100 parts by weight of the base polymer. The above content is, for example, 0.01 parts by weight or more, and may be 0.05 parts by weight or more, 0.1 parts by weight or more, 0.15 parts by weight or more, and even 0.2 parts by weight or more. The above content may be 0.05 to 1 part by weight, and may be 0.1 to 0.5 parts by weight. The adhesive composition may not contain crosslinking agents other than isocyanate-based crosslinking agents.

[0133] (1-2-1-c. Other Components) The adhesive composition may contain known additives as other components. Any suitable additive can be used as such, as long as it does not impair the effects of the present invention. Examples of such additives include silane coupling agents, solvents, colorants, pigments, powders, dyes, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, softeners, antioxidants, anti-aging agents, light stabilizers, UV absorbers, polymerization inhibitors, inorganic fillers, organic fillers, metal powders, particles, and foils. In addition, a redox system with a reducing agent may be used within a controllable range. The total content of additives is, for example, 10 parts by weight or less, 5 parts by weight or less, or even 1 part by weight or less, per 100 parts by weight of the base polymer.

[0134] <1-2-2. Method for Manufacturing the First Adhesive Sheet> The first adhesive sheet 2 can be formed, for example, by drying a coating film of an adhesive composition provided on a substrate. Heating can be used as a means of drying. A release liner may be used as the substrate. The first adhesive sheet 2 formed on the release liner can be transferred, for example, to other layers that the optical laminate may contain (e.g., a polarizing film or a phase difference layer). The substrate may be other layers that the optical laminate may contain.

[0135] As the release liner, known films usable when forming an adhesive sheet from an adhesive composition may be used. Examples of release liners include films, paper, woven fabrics, nonwoven fabrics, porous materials, nets, foams, foils, or laminates thereof, composed of resins, paper, fibers, metals, or composite materials thereof. Examples of resins include polyethylene, polypropylene, polybutene, polybutadiene, polymethylpentene, polyvinyl chloride, vinyl chloride copolymer, polyethylene terephthalate, polybutylene terephthalate, polyurethane, and ethylene-vinyl acetate copolymer.

[0136] The thickness of the release liner is, for example, 5 μm to 200 μm, and may be 5 μm to 100 μm. The surface of the release liner may be subjected to various surface treatments as needed, such as mold release treatment, antifouling treatment, and antistatic treatment.

[0137] The drying temperature of the coated film is, for example, 100°C or higher, and may be 110°C or higher, 120°C or higher, 130°C or higher, or even 140°C or higher. The above drying temperature is, for example, 170°C or lower, 160°C or lower, or even 150°C or lower. The drying time of the coated film can be appropriately adjusted according to the composition of the adhesive composition, and may be, for example, 30 seconds to 300 seconds, 40 seconds to 240 seconds, or even 60 seconds to 180 seconds.

[0138] The method for forming the first adhesive sheet 2 from the adhesive composition is not limited to the above example. For example, the first adhesive sheet 2 may be formed by the following method I or II.

[0139] [Method I] In Method I, a first adhesive sheet 2 is formed by irradiating a coating film of an adhesive composition provided on a substrate with active energy rays. Alternatively, the active energy rays may be irradiated onto a laminate containing the substrate, the coating layer, and the release liner in this order. The coating layer hardens upon irradiation with active energy rays and becomes the first adhesive sheet 2. The adhesive composition to which Method I is applied usually contains a photopolymerization initiator. The adhesive composition to which Method I is applied may also contain partially polymerized monomer components.

[0140] Examples of photopolymerization initiators include benzoin ethers such as benzoin methyl ether, benzoin isopropyl ether, and benzyldimethyl ketal; substituted benzoin ethers such as anisole methyl ether; substituted acetophenones such as 2,2-diethoxyacetophenone and 2,2-dimethoxy-2-phenylacetophenone; α-hydroxyalkylphenones such as 1-hydroxycyclohexyl-phenyl ketone; substituted alpha ketols such as 2-methyl-2-hydroxypropiophenone; aromatic sulfonyl chlorides such as 2-naphthalenesulfonyl chloride; photoactive oximes such as 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime; and benzophenone compounds such as benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, acrylic benzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, and 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone. Thioxanthone compounds such as thioxanthone, 2-chlorthioxanthone, 2-methylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, and 2,4-diethylthioxanthone; 2,4,6-trichloro-s-triazine, 2-phenyl-4,6-bis(trichloromethyl)-s-triazine, 2-(p-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, and 2-(p-tolyl)-4,6-bis(trichloromethyl)-s-triazine Triazine compounds such as 2-piperonyl-4,6-bis(trichloromethyl)-s-triazine, 2,4-bis(trichloromethyl)-6-styryl-s-triazine, 2-(naphtho-1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4-methoxynaphtho-1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2,4-trichloromethyl-(piperonyl)-6-triazine, and 2,4-trichloromethyl-(4'-methoxystyryl)-6-triazine;These include oxime ester compounds such as 1,2-octanedione, 1-[4-(phenylthio)-,2-(O-benzoyl oxime)], and O-(acetyl)-N-(1-phenyl-2-oxo-2-(4'-methoxynaphthyl)ethylidene)hydroxylamine; phosphine compounds such as bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; quinone compounds such as 9,10-phenanthrenequinone, camphorquinone, and ethylanthraquinone; borate compounds; carbazole compounds; imidazole compounds; and titanocene compounds. The adhesive composition may contain one or more photopolymerization initiators.

[0141] Specific examples of photopolymerization initiators include 2,2-dimethoxy-1,2-diphenylethane-1-one (Omnirad 651, IGM Resins), bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (Omnirad 819, IGM Resins), 1-hydroxycyclohexylphenyl ketone (Omnirad 184, IGM Resins), and 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)2-methylpropan-1-one (Omnirad 127D, IGM Resins). However, photopolymerization initiators are not limited to the above examples.

[0142] The amount of photopolymerization initiator in the adhesive composition is, for example, 0.02 to 10 parts by weight, and may be 0.05 to 5 parts by weight, 0.1 to 3 parts by weight, or even 0.2 to 2 parts by weight, per 100 parts by weight of monomer components.

[0143] An example of a release liner is a resin film. Examples of resins include polyesters such as polyethylene terephthalate and polyethylene naphthalate, acetate resins, polyethersulfones, polycarbonates, polyamides, polyimides, polyolefins, (meth)acrylic resins, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl alcohol, polyarylate, and polyphenylene sulfide. The resin is preferably a polyester such as polyethylene terephthalate.

[0144] An example of a substrate is a resin film. The example of the resin is the same as the example of the resin used in the release liner.

[0145] The release liner and / or substrate may have a release layer. The release layer is typically a cured layer of a release agent composition containing a release agent. Various release agents can be used, such as silicone-based release agents, fluorine-based release agents, long-chain alkyl-based release agents, fatty acid amide-based release agents, and silica powder.

[0146] Various coating methods can be applied to form the coated layer, including roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, and die coating.

[0147] Examples of active energy rays include ionizing radiation such as alpha rays, beta rays, gamma rays, neutron rays, and electron beams, as well as visible light and ultraviolet light. The active energy rays are preferably visible light or ultraviolet light having a wavelength shorter than 450 nm, and more preferably ultraviolet light.

[0148] The light source for the active energy rays is, for example, a light irradiation device equipped with an ultraviolet irradiation lamp. Examples of ultraviolet irradiation lamps include ultraviolet LEDs, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, xenon lamps, microwave-excited mercury lamps, black light lamps, chemical lamps, germicidal lamps, low-pressure discharge mercury lamps, and excimer lasers. Two or more ultraviolet irradiation lamps may be combined.

[0149] [Method II] First, a coating film of the adhesive composition is formed on the substrate. However, in addition to the base polymer, the adhesive composition contains a thermal crosslinking agent, a photopolymerization initiator, and a polyfunctional monomer. The thermal crosslinking agent and photopolymerization initiator described above can be used. Next, the coating film is dried to form an adhesive sheet precursor. Heating can be used in combination with drying. Examples of drying temperature and drying time are as described above, but the conditions should not completely cure the coating film. The adhesive sheet precursor may also be formed by adjusting the amount of crosslinking agent incorporated into the adhesive composition. Next, the adhesive sheet precursor is irradiated with light to carry out a photocuring reaction in which the polyfunctional monomer is used as a photocrosslinking agent, thereby forming the first adhesive sheet 2. The light is, for example, visible light or ultraviolet light with a wavelength shorter than 450 nm. The formed first adhesive sheet 2 is a layer formed by curing an adhesive composition containing a base polymer, a polyfunctional monomer, a thermal crosslinking agent, and a photopolymerization initiator. Depending on the photocuring conditions and the type and conditions of the process carried out after curing, some photopolymerization initiator may remain in the formed first adhesive sheet 2. The hardness of the adhesive sheet precursor is usually lower than that of the first adhesive sheet 2. However, a certain level of tackiness can be obtained even in the state of the adhesive sheet precursor. For example, it is possible to form the first adhesive sheet 2 by adhering the adhesive sheet precursor to the object and then proceeding with the photocuring reaction. This method can contribute to improving the anchoring power of the first adhesive sheet 2 to the object.

[0150] A polyfunctional monomer is a compound containing two or more polymerizable functional groups. A polyfunctional monomer may also be a (meth)acrylic monomer. Examples of polyfunctional monomers are monomers having two or more C=C bonds in one molecule, and monomers having one or more C=C bonds and one or more polymerizable functional groups such as epoxy groups, aziridine groups, oxazoline groups, hydrazine groups, or methylol groups in one molecule. Preferably, a polyfunctional monomer is a monomer having two or more C=C bonds in one molecule.

[0151] Examples of polyfunctional monomers include (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,2-ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol diacrylate (NDDA), 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri( Polyfunctional acrylates such as meth)acrylate (TMPTA), tetramethylolmethane tri(meth)acrylate (ester compounds of polyhydric alcohols and (meth)acrylic acid, etc.); allyl (meth)acrylate, vinyl (meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butyl di(meth)acrylate, hexyl di(meth)acrylate, isocyanuric acid EO-modified diacrylate (e.g., Aronics M-923 from Toagosei Co., Ltd.), isocyanuric acid EO-modified di and triacrylates (e.g., Aronics M-315 from Toagosei Co., Ltd.). The polyfunctional monomer is preferably a polyfunctional acrylate, and more preferably trimethylolpropane tri(meth)acrylate, hexanediol di(meth)acrylate, or dipentaerythritol hexa(meth)acrylate.

[0152] <1-2-3. Characteristics, etc.> The thickness of the first adhesive sheet 2 is, for example, 50 μm or less, and may be 30 μm or less, 20 μm or less, 15 μm or less, 10 μm or less, less than 10 μm, 8 μm or less, 6 μm or less, and even 5 μm or less. The lower limit of the above thickness is, for example, 1 μm or more, and may be 2 μm or more, 3 μm or more, and even 4 μm or more. The above thickness is preferably 3 μm or more and less than 10 μm, and is particularly preferably 4 μm to 6 μm.

[0153] The average refractive index n of the first adhesive sheet 2 is, for example, 1.45 or higher, and may be 1.46 or higher, 1.47 or higher, 1.48 or higher, 1.49 or higher, 1.5 or higher, 1.51 or higher, 1.52 or higher, 1.53 or higher, 1.54 or higher, 1.55 or higher, 1.56 or higher, and even 1.57 or higher. The upper limit of the average refractive index n of the first adhesive sheet 2 is, for example, 1.7 or lower, and may be 1.65 or lower, and even 1.6 or lower.

[0154] The gel fraction of the first adhesive sheet 2 is, for example, 50% or more, and may be 55% or more, 60% or more, 65% or more, 70% or more, 75% or more, 80% or more, 82% or more, 84% or more, and even 85% or more. The upper limit of the gel fraction is, for example, 95% or less, and may be 92% or less, and even 90% or less. The gel fraction may be between 85% and 95%.

[0155] The surface of the first adhesive sheet 2 may be surface-treated. An example of surface treatment is an easy-adhesion treatment. This easy-adhesion treatment can be carried out by physical treatments such as corona treatment or plasma treatment, or by chemical treatments such as primer treatment. For example, the surface of the first adhesive sheet 2 that is in contact with the first liquid crystal layer 1 may be surface-treated.

[0156] ≪1-3. Polarizing Film≫ Polarizing film 3 usually includes a polarizer. Preferably, polarizing film 3 further includes a protective film. Polarizing film 3 may further include a first protective film and a second protective film, and may have a laminated structure in which a polarizer is arranged between the first protective film and the second protective film. Polarizing film 3 having such a laminated structure is a so-called double-protection polarizing film. Polarizing film 3 does not necessarily include one of the protective films selected from the group consisting of the first protective film and the second protective film; in other words, it may be a so-called single-protection polarizing film. Polarizing film 3 may also consist of a polarizer alone without including a protective film.

[0157] <1-3-1. Polarizers> Polarizers are typically composed of a film made of a polyvinyl alcohol (PVA) resin containing a dichroic substance (e.g., iodine). Examples of PVA resins include polyvinyl alcohol, partially formalized polyvinyl alcohol, ethylene-vinyl alcohol copolymer, and partially saponified ethylene-vinyl acetate copolymer.

[0158] The PVA resin preferably includes an acetoacetyl-modified PVA resin. The amount of acetoacetyl-modified PVA resin included is, for example, 5% to 20% by weight, and may be 8% to 12% by weight, when the total PVA resin is considered to be 100% by weight.

[0159] The polarizer preferably contains iodide or sodium chloride (sometimes collectively referred to as halide). Examples of iodide include potassium iodide, sodium iodide, and lithium iodide. The halide content in the polarizer is preferably 5 to 20 parts by weight, and more preferably 10 to 15 parts by weight, per 100 parts by weight of PVA resin. In the manufacturing method described later, the halide can be incorporated into the coating solution that forms the PVA resin layer, which is a precursor of the polarizer, and finally introduced into the polarizer. By introducing a halide into the polarizer, the orientation of PVA molecules in the polarizer can be increased, making it possible to realize a polarizer with excellent optical properties (typically, a combination of high polarization degree and high single-element transmittance).

[0160] The polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. The transmittance of the polarizer alone is, for example, 41.0% to 46.0%, and may be 42.0% to 45.0%. The degree of polarization of the polarizer is, for example, 97.0% or higher, and may be 99.0% or higher, and may be 99.9% or higher.

[0161] The thickness of the polarizer is, for example, 12 μm or less, may be 10 μm or less, 1 μm to 8 μm, or 3 μm to 7 μm. Combining such a thin polarizer with a liquid crystal alignment solidification layer can contribute to the thinning of the optical laminate.

[0162] Polarizers can be manufactured by any suitable method. For example, the resin film forming the polarizer may be a single layer of resin film or a laminate of two or more layers.

[0163] Specific examples of polarizers composed of a single layer of resin film include hydrophilic polymer films such as PVA-based films, partially formalized PVA-based films, and partially saponified ethylene-vinyl acetate copolymer films that have been dyed with dichroic substances such as iodine or dichroic dyes and stretched, as well as polyene-based oriented films such as dehydrated PVA or dehydrochlorinated polyvinyl chloride. Preferably, polarizers obtained by dyeing a PVA-based film with iodine and uniaxially stretching it are used because they have excellent optical properties.

[0164] The above-mentioned iodine dyeing is carried out, for example, by immersing the PVA-based film in an iodine aqueous solution. The stretching ratio for the above-mentioned uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment, or during the dyeing process. Alternatively, dyeing may be performed after stretching. If necessary, the PVA-based film may be subjected to swelling treatment, crosslinking treatment, washing treatment, drying treatment, etc. For example, by immersing the PVA-based film in water and washing it before dyeing, not only can dirt and anti-blocking agents on the surface of the PVA-based film be washed away, but the PVA-based film can also be swollen to prevent uneven dyeing.

[0165] Specific examples of laminated polarizers include polarizers obtained using a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate. Polarizers obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be manufactured, for example, by applying a PVA-based resin solution to a resin substrate, drying it to form a PVA-based resin layer on the resin substrate, and obtaining a laminate of the resin substrate and the PVA-based resin layer; or by stretching and dyeing the laminate to make the PVA-based resin layer a polarizer. Preferably, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is formed on one side of the resin substrate.

[0166] Stretching typically involves immersing the polarizer of the laminate in a boric acid aqueous solution for stretching. Furthermore, stretching may further include, if necessary, air-stretching the laminate at a high temperature (e.g., 95°C or higher) before stretching in the boric acid aqueous solution. Preferably, the laminate is subjected to a drying shrinkage treatment in which it shrinks by 2% or more in the width direction by heating while being transported in the longitudinal direction. Typically, this involves applying the following treatments to the laminate in this order: auxiliary air stretching, dyeing, water stretching, and drying shrinkage. By introducing auxiliary stretching, it becomes possible to increase the crystallinity of PVA even when PVA is coated on a thermoplastic resin, making it possible to achieve high optical properties. At the same time, by increasing the orientation of PVA in advance, it is possible to prevent problems such as a decrease in the orientation of PVA or dissolution when immersed in water in the subsequent dyeing and stretching processes, making it possible to achieve high optical properties. Furthermore, when the PVA-based resin layer is immersed in a liquid, the disorder of the orientation of polyvinyl alcohol molecules and the decrease in orientation can be suppressed compared to when the PVA-based resin layer does not contain halides. As a result, the optical properties of the polarizer obtained through processing steps that involve immersing the laminate in a liquid, such as dyeing and underwater stretching, can be improved. Furthermore, the optical properties can be improved by shrinking the laminate in the width direction through a drying shrinkage treatment. The obtained resin substrate / polarizer laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the polarizer), or an appropriate protective layer may be laminated on the peeled surface obtained by removing the resin substrate from the resin substrate / polarizer laminate, or on the surface opposite to the peeled surface, depending on the purpose. Details of such a polarizer manufacturing method are described, for example, in Japanese Patent Application Publication No. 2012-73580 and Japanese Patent No. 6470455. The entire contents of these publications are incorporated herein by reference.

[0167] <1-3-2. Protective Film> The protective film that may be placed on both sides of the polarizer is typically composed of any suitable resin film. Typical materials that make up such a resin film include cellulosic resins such as triacetylcellulose (TAC), cycloolefin resins such as polynorbornene, (meth)acrylic resins, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin resins such as polyethylene, and polycarbonate resins. A typical example of a (meth)acrylic resin is a (meth)acrylic resin having a lactone ring structure. A (meth)acrylic resin having a lactone ring structure is described, for example, in Japanese Patent Publication No. 2000-230016, Japanese Patent Publication No. 2001-151814, Japanese Patent Publication No. 2002-120326, Japanese Patent Publication No. 2002-254544, and Japanese Patent Publication No. 2005-146084. These publications are incorporated herein by reference. From the viewpoint of ease of shaping, cellulose resins are preferred, and TAC is more preferred. From the viewpoint of obtaining polarizing plates with low moisture permeability and excellent durability, cycloolefin resins and (meth)acrylic resins are preferred.

[0168] The protective film may be surface-treated as needed. Examples of surface treatments include hard coating, anti-reflective coating, anti-sticking coating, and anti-glare coating. The protective film may also be treated as needed to improve visibility when viewed through polarized sunglasses (typically by providing (elliptic) polarization functionality or providing ultra-high phase difference). By applying such treatments, excellent visibility can be achieved even when viewing the display screen through polarized lenses such as polarized sunglasses.

[0169] The protective film may be optically isotropic. For example, the in-plane phase difference Re(550) may be 0 nm to 10 nm, and the phase difference Rth(550) in the thickness direction may be -10 nm to +10 nm.

[0170] The thickness of the protective film is, for example, 10 μm to 80 μm, but may also be 12 μm to 40 μm, or 15 μm to 35 μm. If the protective film has a surface treatment, the thickness of the protective film includes the thickness of the surface treatment layer.

[0171] ≪1-4. Second Adhesive Sheet≫ The second adhesive sheet 5 may be a known adhesive sheet that can be used in optical laminates or image display devices. The adhesive sheet described above in the description of the first adhesive sheet 2 may be used as the second adhesive sheet 5. However, in this case, the configuration of the first adhesive sheet 2 and the configuration of the second adhesive sheet 5 may be the same or different.

[0172] The second adhesive sheet 5 can typically be formed by curing an adhesive composition containing a base polymer. The base polymer contained in the adhesive composition may be a (meth)acrylic polymer. In this case, the second adhesive sheet 5 becomes a (meth)acrylic adhesive sheet.

[0173] The base polymer is obtained by polymerization of monomer components. The monomer components preferably include alkyl (meth)acrylate. Specific examples of alkyl (meth)acrylate can be found in the explanation in section 1-2. First Adhesive Sheet.

[0174] The content of alkyl (meth)acrylate in the monomer component is, for example, 10% by weight or more, and may be 25% by weight or more, 50% by weight or more, 75% by weight or more, 80% by weight or more, 85% by weight or more, 90% by weight or more, and even 93% by weight or more. The above content is, for example, 99% by weight or less, 98% by weight or less, and even 95% by weight or less.

[0175] The monomer component may include monomers copolymerizable with alkyl (meth)acrylates (hereinafter sometimes referred to as "copolymer monomers"). Examples of copolymer monomers include hydroxyl group-containing monomers and carboxyl group-containing monomers. For specific examples of copolymer monomers and their content, refer to the explanation in section ≪1-2. First Adhesive Sheet≫.

[0176] The explanation in section 1-2. First Adhesive Sheet can also be applied to the method for forming the base polymer, other components that the adhesive composition may contain, and the method for manufacturing the second adhesive sheet.

[0177] The thickness of the second adhesive sheet 5 is, for example, 100 μm or less, and may be 80 μm or less, 50 μm or less, 40 μm or less, 30 μm or less, or even 20 μm or less. The lower limit of the above thickness is, for example, 1 μm or more, and may be 2 μm or more, 5 μm or more, or even 10 μm or more. The above thickness is preferably 5 μm to 30 μm, and more preferably 10 μm to 20 μm.

[0178] ≪1-5. Shape of Optical Laminate≫ The shape of the optical laminate according to the embodiments of the present invention is not limited. The optical laminate can be distributed and stored, for example, as a wound body formed by winding a strip-shaped optical laminate, or as a single-wafer optical laminate.

[0179] The optical laminate may be rectangular or have an irregular shape. In optical laminates with irregular shapes, the application of stress due to temperature changes tends to be more complex compared to rectangular optical laminates, and the cracks described above tend to occur particularly in the irregularly shaped portions. In this embodiment, even when the optical laminate has an irregular shape, the occurrence and propagation of cracks tend to be suppressed.

[0180] In this specification, "rectangle" refers to the rectangle, which is the most common shape for a display surface in an image display device. Rectangles include squares. On the other hand, "irregular shape" refers to a shape other than a rectangle, and includes, for example, circles, ellipses, shapes that combine circles and / or ellipses, polygons other than rectangles, shapes that include curves on the outer perimeter, shapes with U-shaped, V-shaped, or irregular cutouts (sometimes called "notches") on the outer perimeter, shapes with depressions or through holes in the surface, and irregular shapes. Optical laminates with irregular shapes are often applied to image display devices in automotive meters, smartphones, smartwatches, and other portable information devices. Examples of optical laminates with irregular shapes are shown in Figures 4 to 10. Figures 4 to 10 show optical laminates with irregular shapes in a plan view. In Figures 4 to 10, reference numeral 21 denotes a notch, and reference numeral 22 denotes a through hole. Optical laminates with irregular shapes are not limited to those shown in Figures 4 to 10.

[0181] ≪1-6. Applications of Optical Laminates≫ Optical laminates according to embodiments of the present invention are typically used in image display devices. In other words, optical laminates may be used for image display devices. Image display devices include, for example, EL displays such as liquid crystal displays, organic EL displays, and inorganic EL displays. The applications of optical laminates are not limited to the above examples. Furthermore, the applications of optical laminates do not have to be for use in extremely low temperature environments. Image display devices that may use optical laminates according to embodiments of the present invention are not limited to the above examples.

[0182] ≪≪2. Image Display Device≫≫ Figure 11 is a typical schematic cross-sectional view of an image display device according to an embodiment of the present invention. The image display device 20 in Figure 11 comprises an optical laminate 10 (more specifically, an optical laminate 10D shown in Figure 2C), and further comprises, for example, an image forming layer 6 and a substrate 7. The optical laminate 10, the image forming layer 6 and the substrate 7 are stacked in this order, for example. The image forming layer 6 and the substrate 7 may have the same configuration as the image forming layer and substrate of known image display devices. Examples of the image forming layer 6 include an organic EL layer and a liquid crystal layer.

[0183] The image display device 20 may be an organic EL display or a liquid crystal display. However, the image display device 20 is not limited to the above examples. The image display device 20 may be an electroluminescent (EL) display, a plasma display (PD), a field emission display (FED), etc. The image display device 20 can be used for home appliance applications, automotive applications, public information display (PID) applications, etc.

[0184] The image display device according to an embodiment of the present invention may employ any suitable configuration as its structure, provided that it includes an optical laminate according to an embodiment of the present invention.

[0185] The present invention will be specifically described below with reference to examples, but the present invention is not limited in any way to these examples. Where "parts" is mentioned, it means "parts by weight" unless otherwise specified, and where "%" is mentioned, it means "percent by weight" unless otherwise specified.

[0186] <Preparation of Liquid Crystal Layer> [First Liquid Crystal Alignment Solidification Layer] A photopolymerizable liquid crystal compound exhibiting a nematic liquid crystal phase (BASF, "Paliocolor LC242") was dissolved in cyclopentanone to prepare a solution with a solid content of 30% by weight. A surfactant (BYK-361N, BIC Chemie Co., Ltd.) and a photopolymerization initiator (Omnirad907, IGM Resins) were added to this solution to prepare a liquid crystal composition solution. The amounts of surfactant and polymerization initiator added were 0.01 parts by weight and 3 parts by weight, respectively, per 100 parts by weight of the photopolymerizable liquid crystal compound. A biaxially oriented norbornene-based film (Zeonor Film, 33 μm thick, Re(550) = 135 nm, manufactured by Nippon Zeon Co., Ltd.) was prepared as a substrate. The above liquid crystal composition was applied to this substrate using a bar coater so that Re(550) was 240 nm, and the liquid crystal was oriented by heating at 100°C for 3 minutes. After cooling to room temperature, the substrate was exposed to a nitrogen atmosphere with an integrated light intensity of 400 mJ / cm². 2The material was photocured by irradiation with ultraviolet light to obtain a laminate having a substrate / first liquid crystal alignment solidified layer configuration. The first liquid crystal alignment solidified layer was homogeneously oriented, with a thickness of 1.7 μm and an average refractive index of 1.590.

[0187] [Second Liquid Crystal Alignment Solidification Layer] A laminate having the configuration of substrate / second liquid crystal alignment solidification layer (Re(550) = 130 nm) was obtained in the same manner as the first liquid crystal alignment solidification layer, except that the coating thickness was changed. The second liquid crystal alignment solidification layer was homogeneously oriented, with a thickness of 0.92 μm and an average refractive index of 1.590.

[0188] <Preparation of a phase difference layer including a liquid crystal alignment solidification layer> [Adhesive composition] Acryloylmorpholine (ACMO) (manufactured by KJ Chemicals, trade name "ACMO") 20 parts by weight, unsaturated fatty acid hydroxyalkyl ester modified epsilon-caprolactone (manufactured by Daicel Corporation, trade name "PLACCEL FA1DDM") 10 parts by weight, mixture of fluorene-based acrylate and reactive acrylate (manufactured by Osaka Gas Chemical Co., Ltd., trade name "Ogusol EA-F5710") 60 parts by weight, acrylic acid polymer (manufactured by Toagosei Co., Ltd., trade name "ARUFON UP-1190") 5 parts by weight, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one (IGM Three parts by weight of Resins (product name "Omnirad907") and two parts by weight of 2,4-diethylthioxanthone (product name "KAYACRE DETX-S") were mixed at 25°C for 1 hour to obtain an adhesive composition.

[0189] [Phase Difference Layer] The first liquid crystal alignment solidified layer and the second liquid crystal alignment solidified layer were bonded together via an adhesive composition. Specifically, the adhesive composition was applied so that the total thickness of the adhesive was 1.0 μm, and the two liquid crystal alignment solidified layers were bonded together using a roll laminating machine. Subsequently, the adhesive composition was cured by irradiating it with UV light from the side of the second liquid crystal alignment solidified layer. This obtained a phase difference layer. The UV light irradiation was performed using an irradiation device equipped with a gallium-filled metal halide lamp (Fusion UV Systems, "Light HAMMER10", bulb: V-bulb) with a peak illuminance of 1600 mW / cm². 2 Total irradiation dose: 1000 mJ / cm²2 The experiment was conducted under conditions of wavelength 380–440 nm.

[0190] <Preparation of Polarizing Film> [Polarizer] A long, amorphous isophthalic copolymer polyethylene terephthalate film (thickness 100 μm) with a Tg of approximately 75°C was used as the thermoplastic resin substrate, and one side of the resin substrate was subjected to corona treatment. 100 parts by weight of a PVA-based resin, which was a mixture of polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosephymer") in a 9:1 ratio, was mixed with 13 parts by weight of potassium iodide, and this mixture was dissolved in water to prepare a PVA aqueous solution (coating solution). The above PVA aqueous solution was applied to the corona-treated surface of the resin substrate and dried at 60°C to form a PVA-based resin layer with a thickness of 13 μm, thereby producing a laminate. The obtained laminate was uniaxially stretched 2.4 times in the longitudinal direction (longitudinal direction) in an oven at 130°C (air-assisted stretching treatment). Next, the laminate was immersed for 30 seconds in an insolubilization bath at a liquid temperature of 40°C (a boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) (insolubilization treatment). Next, it was immersed for 60 seconds in a staining bath at a liquid temperature of 30°C (a iodine aqueous solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with 100 parts by weight of water) while adjusting the concentration so that the final transmittance (Ts) of the polarizer obtained would be the desired value (staining treatment). Next, it was immersed for 30 seconds in a crosslinking bath at a liquid temperature of 40°C (a boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) (crosslinking treatment). Subsequently, the laminate was immersed in a boric acid aqueous solution (boric acid concentration 4% by weight, potassium iodide concentration 5% by weight) at a liquid temperature of 70°C and uniaxially stretched between rolls with different peripheral speeds to achieve a total stretch ratio of 5.5 times in the longitudinal direction (water stretching treatment). After that, the laminate was immersed in a washing bath at a liquid temperature of 20°C (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) (washing treatment). After that, while drying in an oven maintained at approximately 90°C, it was brought into contact with a heated roll made of stainless steel with a surface temperature maintained at approximately 75°C (drying shrinkage treatment). In this way, a polarizer with a thickness of approximately 5 μm was formed on the resin substrate, and a laminate having a resin substrate / polarizer configuration was obtained. The transmittance Ts of the polarizer alone was 43.3%.

[0191] [Polarizing Film] An HC-COP film was bonded to the surface of the polarizer (the side opposite to the resin substrate) via an ultraviolet-curing adhesive. The HC-COP film is a cycloolefin resin (COP) film (25 μm thick) with an HC layer (4 μm thick) formed on it, and it was bonded so that the COP film was on the polarizer side. The COP film had a Re(550) of 135 nm. Next, the resin substrate was peeled off, and a triacetylcellulose (TAC) film (25 μm thick) was bonded to the peeled surface via an ultraviolet-curing adhesive. In this way, a polarizing film having the structure of HC layer / COP film (protective film) / polarizer / TAC film (protective film) was obtained.

[0192] <Preparation of Adhesive Composition> [(Meth)acrylic Polymer P1] 69 parts by weight of phenoxybenzyl acrylate (POB-A), 1 part by weight of 4-hydroxybutyl acrylate (4HBA), and 30 parts by weight of n-butyl acrylate (BA) were charged into a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and condenser. Furthermore, 0.1 parts by weight of 2,2'-azobisisobutyronitrile (AIBN) was added to 100 parts by weight of the monomer mixture as a polymerization initiator along with ethyl acetate. After introducing nitrogen gas and purging with nitrogen while gently stirring, the polymerization reaction was carried out for 7 hours while maintaining the liquid temperature in the flask at around 55°C. Subsequently, ethyl acetate was added to the resulting reaction solution to adjust the solid content concentration to 30% by weight to obtain a solution of (meth)acrylic polymer P1.

[0193] [Preparation of (meth)acrylic polymers P2 to P7] Solutions of (meth)acrylic polymers P2 to P7 were obtained in the same manner as for (meth)acrylic polymer P1, except that the type and amount of monomer were changed as shown in Table 1 below. The weight-average molecular weight (Mw) of (meth)acrylic polymers P2 to P7 was evaluated by gel permeation chromatography (GPC) under the following conditions: • Analytical instrument: Waters, Acquity APC • Column: Tosoh, G7000HXL + GMHXL + GMHXL • Column temperature: 40°C • Eluent: Tetrahydrofuran (acid added) • Flow rate: 0.8 mL / min • Injection volume: 100 μL • Detector: Differential refractometer (RI) • Standard sample: Agilent, polystyrene (PS)

[0194]

[0195] The abbreviations in Table 1 are as follows: POB-A: Phenoxybenzyl acrylate BA: n-butyl acrylate 4HBA: 4-hydroxybutyl acrylate BzA: Benzyl acrylate ACMO: Acryloylmorpholine AA: Acrylic acid

[0196] [Adhesive Composition A1] Adhesive composition A1 was obtained by blending 0.3 parts by weight of an isocyanate crosslinking agent (trimethylolpropane / xylylene diisocyanate trimer adduct, manufactured by Mitsui Chemicals, trade name "Takenate D-110N") with 100 parts by weight of the solid content of the solution of the above (meth)acrylic polymer P1.

[0197] [Adhesive Compositions A2 to A8] Adhesive compositions A2 to A8 were obtained by the same method as adhesive composition A1, except that the types and amounts of (meth)acrylic polymer, monomer, crosslinking agent, and additives were changed as shown in Table 2.

[0198]

[0199] The abbreviations in Table 2 are as follows: (Monomer) TMPTA: Trimethylolpropane triacrylate (Crosslinking agent) D110N: Trimethylolpropane / xylylene diisocyanate trimer adduct (manufactured by Mitsui Chemicals, trade name "Takenate D-110N") C / L: Trimethylolpropane / tolylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name "Coronate L") Peroxide: Benzoyl peroxide (manufactured by Nippon Oil & Fats, Naiper BMT) (Photopolymerization initiator) Omnirad184: 1-Hydroxycyclohexylphenyl ketone (manufactured by IGM Resins, Omnirad184) (Additive) KBM-403: Silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-403")

[0200] <Preparation of the First Adhesive Sheet> [First Adhesive Sheet S1] Adhesive composition A1 was applied to a release liner (Mitsubishi Chemical Corporation, MRF38-NS2) to create a coating film. A fountain coater was used to apply the adhesive composition A1. The coating film formed by the application was dried in an air-circulating constant-temperature oven at 120°C for 2 minutes to produce the first adhesive sheet S1 (thickness 5 μm).

[0201] [First Adhesive Sheets S2-S4] First adhesive sheets S2-S4 (thickness 5 μm) were prepared in the same manner as the first adhesive sheet S1, except that adhesive compositions A2-A4 were used instead of adhesive composition A1.

[0202] [First Adhesive Sheet S5] Adhesive composition A5 was applied to a release liner (Mitsubishi Chemical Corporation, MRF38-NS2) to create a coating film. A fountain coater was used to apply adhesive composition A5. The coating film formed by the application was dried in an air-circulating constant-temperature oven at 110°C for 2 minutes to form an adhesive sheet precursor. Next, the polarizing film prepared above was bonded to the exposed surface of the adhesive sheet precursor to obtain a laminate having the configuration of polarizing film / adhesive sheet precursor / release liner. Next, the release liner was peeled off from the adhesive sheet precursor, and the phase difference layer prepared above was bonded to the exposed surface of the adhesive sheet precursor to obtain a laminate having the configuration of polarizing film / adhesive sheet precursor / phase difference layer. When bonding the phase difference layer, the exposed surface of the first liquid crystal alignment solidification layer was corona treated, and then the exposed surface and the adhesive sheet precursor were bonded together. Next, ultraviolet light (cumulative light intensity 1000 mJ / cm²) was applied to the adhesive sheet precursor from a high-pressure mercury lamp. 2 The material was photocured by irradiating it with a light source to produce a first adhesive sheet S5 (thickness 20 μm) and a laminate containing the first adhesive sheet S5. In this laminate, the first adhesive sheet was in contact with the first liquid crystal alignment solidification layer (average refractive index 1.59) contained in the phase difference layer.

[0203] [First Adhesive Sheets S6-S7] First adhesive sheets S6-S7 (thickness 5 μm) were prepared in the same manner as the first adhesive sheet S1, except that adhesive compositions A6 and A7 were used instead of adhesive composition A1.

[0204] [First Adhesive Sheet S8] The first adhesive sheet S8 (thickness 5 μm) was prepared in the same manner as the first adhesive sheet S1, except that adhesive composition A8 was used instead of adhesive composition A1 and the drying conditions for the coating film were set to 155°C for 2 minutes.

[0205] <Evaluation of the First Adhesive Sheet> [Glass Transition Temperature (Tg)] (First Adhesive Sheets S1-S4, S6-S8) The Tg of the first adhesive sheets S1-S4 and S6-S8 was measured by the following method. The release liner was peeled off from the first adhesive sheet to be evaluated, and a laminate (1 mm thick) was created by stacking multiple sheets. A disc with a diameter of 8 mm was cut out to be used as a sample for measurement. Next, dynamic viscoelasticity measurements were performed using a dynamic viscoelasticity measuring device (TA Instruments, ARES-G2) under the following measurement conditions. The peak top temperature of tanδ obtained from the measurement was identified as Tg. Measurement conditions Frequency: 1 Hz Deformation mode: Torsion Measurement temperature: -70°C to 150°C Heating rate: 5°C / min

[0206] (First Adhesive Sheet S5) The Tg of the first adhesive sheet S5 was measured by the following method. The adhesive sheet (thickness 20 μm) was exposed by peeling off the release liner from the first adhesive sheet to be evaluated, and a strip 10 mm wide and 50 mm long was cut out to be used as a sample for measurement. Next, dynamic viscoelasticity measurement was performed using a dynamic viscoelasticity measuring device (TA Instruments, RSA-G2) under the following measurement conditions. The peak top temperature of tanδ (= tensile storage modulus E' / tensile loss modulus E'') obtained from the measurement was identified as Tg. Measurement conditions Chuck distance: 15 mm Frequency: 1 Hz Deformation mode: tensile Measurement temperature: -70°C to 150°C Heating rate: 5°C / min

[0207] [Storage Modulus G'] For each of the first adhesive sheets prepared, the storage modulus G'(-40°C), storage modulus G'(-10°C), storage modulus G'(0°C), and storage modulus G'(85°C) were determined from the dynamic viscoelasticity measurement results when measuring Tg. Furthermore, the ratio G'(-40°C) / G'(-10°C) was determined from the determined G'(-40°C) and G'(-10°C), and the ratio G'(-40°C) / G'(0°C) was determined from the determined G'(-40°C) and G'(0°C). For the first adhesive sheet S5, 1 / 3 of the value of the tensile storage modulus E' obtained by dynamic viscoelasticity measurement was determined as the storage modulus G'.

[0208] [Average refractive index n] The average refractive index of the first adhesive sheet was measured using an Abbe refractometer under the conditions of a measurement temperature of 25°C and a measurement wavelength of 589 nm. An ATAGO DR-4M Abbe refractometer was used. When measuring the refractive index, only the first adhesive sheet was set on a prism of the Abbe refractive index diameter (the release liner was removed).

[0209] The evaluation results for the first adhesive sheet are shown in Table 3 below.

[0210]

[0211] [Fabrication of Optical Laminates] (Example 1) The polarizing film prepared above was bonded to the exposed surface of the first adhesive sheet S1 to obtain a laminate having the configuration of polarizing film / first adhesive sheet / release liner. In this laminate, the first adhesive sheet was in contact with the TAC film (average refractive index 1.49) contained in the polarizing film. Next, the release liner was peeled off from the first adhesive sheet, and the phase difference layer prepared above was bonded to the exposed surface of the first adhesive sheet. When bonding the phase difference layer, the exposed surface of the first liquid crystal alignment solidification layer was corona treated, and then the exposed surface was bonded to the first adhesive sheet. This resulted in obtaining a laminate having the configuration of polarizing film / first adhesive sheet / phase difference layer. In this laminate, the first adhesive sheet was in contact with the first liquid crystal alignment solidification layer (average refractive index 1.59) contained in the phase difference layer. Next, the exposed surface of the second liquid crystal alignment solidification layer of the laminate was plasma-treated, and then the exposed surface and the exposed surface of the second adhesive sheet were bonded together to obtain a laminate having the configuration of polarizing film / first adhesive sheet / phase difference layer / second adhesive sheet / release liner (this configuration will be referred to as "Configuration A"). For the second adhesive sheet, a commercially available (meth)acrylic adhesive sheet (thickness 30 μm) formed on a release liner (thickness 38 μm) was used.

[0212] A through-hole (a circle with a diameter of 2 mm in plan view) was created in the obtained laminate by end milling, passing through the laminate vertically, to obtain the optical laminate of Example 1 having an irregular shape. The size of this optical laminate was 160 mm in length and 80 mm in width, with one of the through-holes located near the center of the short side and at a distance of 2 mm from the short side. In addition, the absorption axis of the polarizing film in the optical laminate was 0° with respect to the long side. The size, the position of the through-hole, and the absorption axis of the polarizing film were the same in the other examples and comparative examples.

[0213] (Examples 2-4 and Comparative Examples 1-3) Optical laminates of Examples 2-4 and Comparative Examples 1-3 were obtained by the same method as in Example 1, except that the first adhesive sheet S1 was changed as shown in Table 4 below.

[0214] (Example 5) In the preparation of the first adhesive sheet S5, a laminate having the configuration of polarizing film / first adhesive sheet / phase difference layer was formed. After plasma treatment of the exposed surface of the second liquid crystal alignment solidification layer, the exposed surface and the exposed surface of the second adhesive sheet were bonded together to obtain a laminate having the configuration of polarizing film / first adhesive sheet / phase difference layer / second adhesive sheet / release liner (having configuration A). For the second adhesive sheet, a commercially available (meth)acrylic adhesive sheet (thickness 30 μm) formed on a release liner (thickness 38 μm) was used. The obtained laminate was subjected to end milling in the same manner as in Example 1 to obtain the optical laminate of Example 5 having an irregular shape.

[0215]

[0216] (Example 6) <Preparation of adhesive for bonding polarizing film and first liquid crystal alignment solidification layer> 10 parts by weight of hydroxyethyl acrylamide (trade name "HEAA", manufactured by KJ Chemicals), 4 parts by weight of 2-acetoacetoxyethyl methacrylate (trade name "AAEM", manufactured by Mitsubishi Chemicals), 60 parts by weight of acryloylmorpholine (trade name "ACMO", manufactured by KJ Chemicals), 11 parts by weight of tripropylene glycol diacrylate (trade name "Aronics M-220", manufactured by Toagosei Co., Ltd.), 1 part by weight of 4-vinylphenylboronic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 10 parts by weight of acrylic oligomer (trade name "ARUFON UP-1190", manufactured by Toagosei Co., Ltd.), bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (trade name "Omnirad819", IGM An adhesive was prepared by stirring 1 part by weight of (manufactured by Resins), 2 parts by weight of 1-hydroxycyclohexylphenyl ketone (trade name "Omnirad 184", manufactured by IGM Resins), and 1 part by weight of diethylthioxanthone (trade name "KAYACUREDETX-S", manufactured by Nippon Kayaku Co., Ltd.) at 50°C for 1 hour.

[0217] <Fabrication of Optical Laminate> The first liquid crystal alignment solidification layer side of the laminate having the above-prepared substrate / first liquid crystal alignment solidification layer configuration was bonded to the protective film of the above-prepared polarizing film (thickness 61 μm) via the above-prepared adhesive (thickness 1 μm). Then the substrate was peeled off to obtain a laminate having the configuration of polarizing film / adhesive / first liquid crystal alignment solidification layer. Next, the exposed surface of the first liquid crystal alignment solidification layer was plasma treated, and then the exposed surface was bonded to the exposed surface of the first adhesive sheet S3 formed on the release liner to obtain a laminate having the configuration of polarizing film / adhesive / first liquid crystal alignment solidification layer / first adhesive sheet / release liner. Next, the release liner was peeled off from the first adhesive sheet, and the second liquid crystal alignment solidification layer side of the above-prepared substrate / second liquid crystal alignment solidification layer configuration was bonded to the exposed surface of the first adhesive sheet exposed by peeling. Before bonding, the exposed surface of the second liquid crystal alignment solidification layer in the laminate was corona treated. Next, the substrate was peeled off to obtain a laminate having the configuration of polarizing film / adhesive / first liquid crystal alignment solidification layer / first adhesive sheet / second liquid crystal alignment solidification layer. Next, the exposed surface of the second liquid crystal alignment solidification layer was plasma treated, and then the exposed surface and the exposed surface of the second adhesive sheet were bonded together to obtain a laminate having the configuration of polarizing film / adhesive / first liquid crystal alignment solidification layer / first adhesive sheet / second liquid crystal alignment solidification layer / second adhesive sheet / release liner (this configuration will be referred to as "Configuration B").

[0218] A through-hole (a circle with a diameter of 2 mm in plan view) was created in the obtained laminate by end milling, passing through the laminate vertically, to obtain the optical laminate of Example 6 having an irregular shape. The size of this optical laminate was 160 mm in length and 80 mm in width, with one of the through-holes located near the center of the short side and at a distance of 2 mm from the short side. In addition, the absorption axis of the polarizing film in the optical laminate was 0° with respect to the long side.

[0219] <Evaluation of Optical Laminates> [HC Test] The fabricated optical laminates were subjected to a heat cycle (HC) test using the following method. First, the optical laminate was fixed to the surface of a glass plate (Corning Eagle XG) using an acrylic adhesive sheet (thickness 25 μm) with a polarizing film as the bonding surface. Fixation was carried out in an atmosphere of 23°C and 50% RH. Next, the optical laminate, together with the glass plate, was placed in a heat cycle tester, and an HC test of 100 or 300 cycles was performed under the following test conditions. After the test, the optical laminate was observed as a transmitted image using an optical microscope (magnification 10x), and cracks were confirmed near the through holes, which are irregular parts. Ten optical laminates were prepared for each example and comparative example, and the percentage of optical laminates in which cracks were confirmed in the HC test (crack frequency) was determined from the ten prepared optical laminates. HC test conditions: Hold at -40°C for 30 minutes, raise to 85°C and hold for 30 minutes, then cool down to -40°C. Repeat this cycle 100 or 300 times. However, the heating rate and cooling rate shall be 10°C / min.

[0220] [Durability Test] (80°C Durability) The fabricated optical laminate was subjected to an 80°C durability test using the following method. First, the release liner was peeled off, and the exposed second adhesive sheet was bonded to the surface of a glass plate (Corning Eagle XG) using a hand roller. The bonding was performed in an atmosphere of 23°C and 50% RH humidity. Next, it was treated in an autoclave at 50°C and 5 atmospheres (absolute pressure) for 15 minutes, and then left to cool to 23°C to stabilize the bond of the laminate to the glass plate. Next, the entire structure was left in a heated atmosphere of 80°C for 500 hours. After the period, it was returned to an atmosphere of 23°C and 50% RH humidity, and the first adhesive sheet portion was visually inspected to check for peeling. High-temperature durability was evaluated according to the following criteria: A: No peeling was observed. B: Minute bubbles were observed at the edges, but this is at a level that does not pose a practical problem.

[0221] (65°C 90% durability) The fabricated optical laminates were evaluated for their durability at high temperature and high humidity, except that the heating atmosphere in which the optical laminates bonded to the glass plate were left was set to a temperature of 65% and a relative humidity of 90%, the same conditions as for the 80°C durability test. The evaluation criteria were the same as for the 80°C durability test.

[0222] [Anchoring Force] (Examples 1-5, Comparative Examples 1-3) For the optical laminates (having configuration A) prepared in Examples 1-5 and Comparative Examples 1-3, the anchoring force between the first adhesive sheet and the polarizing film was measured by the following method. First, the laminate having the configuration of polarizing film / first adhesive sheet / release liner prepared above was cut to a width of 25 mm x length of 150 mm to make a test piece. Next, the release liner was peeled off the test piece to expose the first adhesive sheet, and an evaluation sheet (manufactured by Oike Kogyo Co., Ltd., 125 Tetrilite OES, width 30 mm x length 150 mm) was placed on top of it, and a 2 kg roller was passed back and forth once to press them together. Next, the entire surface of the polarizing film on the test piece was placed on a stainless steel test plate (made of SUS304, width 40 mm x length 120 mm) via double-sided tape (manufactured by Nitto Denko Co., Ltd., No. 531), and a 2 kg roller was passed back and forth once to press them together. Next, using a tensile testing machine (Shimadzu Corporation, Autograph SHIMAZU AG-I 10KN), the evaluation sheet was held in place, and the first adhesive sheet and polarizing film were delaminated at a peeling angle of 180° and a peeling speed of 50 mm / min. The average value of the peeling force measured during delamination was identified as the anchoring force. The test was conducted at 23°C.

[0223] (Example 6) The anchoring force between the first adhesive sheet and the first liquid crystal alignment solidification layer was measured for the optical laminate (having structure B) prepared in Example 6 by the following method. First, the optical laminate was cut to a size of 25 mm wide x 150 mm long to make a test piece. Next, the entire surface of the polarizing film on the test piece was placed on a stainless steel test plate (SUS304, 40 mm wide x 120 mm long) via double-sided tape (Nitto Denko Corporation, No. 531), and a 2 kg roller was passed back and forth once to press them together. Next, the release liner was peeled off the test piece to expose the second adhesive sheet, and an evaluation sheet (Oike Kogyo Co., Ltd., 125 Tetrilite OES, 30 mm wide x 150 mm long) was placed on top of it, and a 2 kg roller was passed back and forth once to press them together. Next, using a tensile testing machine (Shimadzu Corporation, Autograph SHIMAZU AG-I 10KN), the evaluation sheet was held in place and delamination was performed between the first adhesive sheet and the first liquid crystal alignment solidification layer under conditions of a delamination angle of 180° and a delamination speed of 50 mm / min. The average value of the delamination force measured during delamination was identified as the anchoring force. The test was conducted at 23°C.

[0224] Based on the measured anchoring force, each optical laminate was evaluated according to the following criteria: A: Anching force of 1.5 N or more; B: Anching force between 0.5 N and less than 1.5 N; C: Anching force less than 0.5 N.

[0225] [Appearance (Linear Irregularities, a Type of Display Irregularity)] Linear irregularities, a type of display irregularity, were evaluated for the fabricated optical laminate using the following method. First, the release liner was peeled off to expose the second adhesive sheet, which was then attached to a V3 reflector (manufactured by NEODIS Co., Ltd.) and used as a test sample. The obtained test sample was observed visually under a three-wavelength fluorescent lamp and evaluated according to the following criteria. A: No linear irregularities were observed. B: Slight linear irregularities were observed. C: Linear irregularities were observed, but were to a degree that was practically acceptable. D: Linear irregularities were significant.

[0226] The evaluation results are shown in Table 5 below.

[0227]

[0228] As shown in Table 5, in the optical laminates of the examples where the Tg of the first adhesive sheet was -10°C or higher, the frequency of cracks measured by HC testing was suppressed compared to the comparative example.

[0229] The optical laminate of the present invention can be used in image display devices such as EL displays and liquid crystal displays.

Claims

1. An optical laminate comprising a first liquid crystal layer and a first adhesive sheet adjacent to the first liquid crystal layer, wherein the glass transition temperature (Tg) of the first adhesive sheet is -10°C or higher.

2. The optical laminate according to claim 1, wherein the ratio of the storage modulus G'(-40°C) of the first adhesive sheet at -40°C to the storage modulus G'(-10°C) of the first adhesive sheet at -10°C [G'(-40°C) / G'(-10°C)] is 50 or less.

3. The optical laminate according to claim 1, wherein the first adhesive sheet has a first main surface in contact with the first liquid crystal layer and a second main surface opposite to the first main surface, and the optical laminate comprises a further layer in contact with the second main surface of the first adhesive sheet, and when the average refractive index of the first adhesive sheet is n, the average refractive index of the first liquid crystal layer is n1, and the average refractive index of the further layer is n2, the absolute value of the value calculated by the formula: {(n1 + n2) / 2 - n} is 0.08 or less.

4. The optical laminate according to claim 1, further comprising a polarizing film located on the opposite side of the first liquid crystal layer from the first adhesive sheet.

5. The optical laminate according to claim 4, further comprising a second liquid crystal layer located on the opposite side of the first adhesive sheet from the first liquid crystal layer.

6. The optical laminate according to claim 5, wherein the first liquid crystal layer and the second liquid crystal layer are joined together via an adhesive.

7. The optical laminate according to claim 5, further comprising a second adhesive sheet located on the opposite side of the first liquid crystal layer from the second liquid crystal layer.

8. The optical laminate according to claim 1, further comprising a second liquid crystal layer located on the opposite side of the first liquid crystal layer from the first adhesive sheet, wherein the first liquid crystal layer and the second liquid crystal layer are joined via the first adhesive sheet.

9. The optical laminate according to claim 8, further comprising a polarizing film located on the opposite side of the first adhesive sheet from the first liquid crystal layer.

10. The optical laminate according to claim 8, further comprising a second adhesive sheet located on the opposite side of the first liquid crystal layer from the second liquid crystal layer.

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

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

13. The optical laminate according to claim 11, wherein the monomer component constituting the base polymer includes an aromatic ring-containing monomer.

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

15. The optical laminate according to claim 13, wherein the content of the aromatic ring-containing monomer in the monomer component is 60% by weight or more.

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

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

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