Adhesive sheet, optical laminate, and image display device

Abstract

The present invention provides an adhesive sheet that is suitable for suppressing the breakage of an image display panel due to a localized load. An adhesive sheet according to an embodiment of the present invention conforms to at least one requirement selected from the group consisting of requirements (i)-(iii), below. (i) The coloration ratio X1 specified in test 1 satisfies X1 ≤ 1.1%. (ii) The coloration ratio X2 specified in test 2 satisfies X2 ≤ 1.8%. (iii) The coloration ratio X3 specified in test 3 satisfies X3 ≤ 4.6%.

Description

Pressure-sensitive adhesive sheet, optical laminate and image display device

[0001] The present invention relates to a pressure-sensitive adhesive sheet, an optical laminate, and an image display device.

[0002] Due to their image formation methods, image display devices (such as liquid crystal display devices, organic EL display devices, and quantum dot display devices) often have an optical laminate including an optical element such as a polarizing film disposed on at least one side of the display cell. Widely known optical elements include anti-reflection layers and anti-glare layers for preventing reflection of external light and glare on the display screen (Patent Document 1). Pressure-sensitive adhesive sheets are typically used to bond optical elements together or to bond the optical laminate to an image display panel.

[0003] Japanese Patent Application Laid-Open No. 2018-155998

[0004] Lighter weight and greater flexibility are being sought for image display devices, and in order to meet this demand, measures such as reducing the thickness of the optical members included in the optical laminate or omitting some of the optical members have been considered. However, when these measures are taken, the image display panel tends to be more susceptible to damage due to the application of a local load (for example, a load due to contact with a touch pen) to the image display device.

[0005] An object of the present invention is to provide a pressure-sensitive adhesive sheet that is suitable for suppressing damage to an image display panel due to a local load.

[0006] [1] In a pressure-sensitive adhesive sheet according to an embodiment of the present invention, at least one selected from the group consisting of the following requirements (i) to (iii) is satisfied: (i) The coloring ratio X1 determined by Test 1 below satisfies X1≦1.1%. (ii) The coloring ratio X2 determined by Test 2 below satisfies X2≦1.8%. (iii) The coloring ratio X3 determined by Test 3 below satisfies X3≦4.6%. Test 1: A laminate S1 is prepared in which a glass plate, a press scale (manufactured by Fujifilm Corporation, for medium pressure (MS)), and the pressure-sensitive adhesive sheet are laminated in this order. A piercing test T1 is performed in which a piercing jig with a tip curvature radius R of 550 μm is used to pierce the laminate S1 from the pressure-sensitive adhesive sheet side at a piercing speed of 0.9 mm / min until a load of 0.2 kgf is reached. After the piercing test T1, the surface of the prescale is observed using an optical microscope under the conditions of a magnification of 300 times and a field of view of 840 μm × 1120 μm. 2 ) relative to the area A1 (μm 2 ) is specified as the coloring ratio X1 (%). Test 2: A laminate S2 is prepared by laminating a glass plate, a prescale (manufactured by Fujifilm Corporation, for medium pressure (MS)), the pressure-sensitive adhesive sheet, and an antireflection laminate having a thickness of 85 μm in this order. A piercing test T2 is performed in which a piercing jig with a tip curvature radius R of 550 μm is used to pierce the laminate S2 from the antireflection laminate side at a piercing speed of 0.9 mm / min until a load of 0.5 kgf is reached. After the piercing test T2, the surface of the prescale is observed using an optical microscope at a magnification of 300 times and a field of view of 840 μm x 1120 μm. The area A (μm 2 ) to the area A2 (μm 2) is specified as the coloring ratio X2 (%). Test 3: A laminate S3 is prepared by laminating a glass plate, a prescale (manufactured by Fujifilm Corporation, for medium pressure (MS)), a polarizing film with a 104 μm thick retardation film, the pressure-sensitive adhesive sheet, and an antireflection laminate with a thickness of 85 μm in this order. A piercing test T3 is performed in which a piercing jig with a tip curvature radius R of 550 μm is used to pierce the laminate S3 from the antireflection laminate side at a piercing speed of 0.9 mm / min until the load reaches 1.0 kgf. After the piercing test T3, the surface of the prescale is observed using an optical microscope at a magnification of 300 times and a field of view of 840 μm x 1120 μm. The area A (μm 2 ) to the area A3 (μm 2) is specified as the coloring ratio X3 (%). [2] The pressure-sensitive adhesive sheet described in [1] above may include a polymer P1 formed from a photocurable composition (I) and a polymer P2 formed from a photocurable composition (II) different from the photocurable composition (I). [3] In the pressure-sensitive adhesive sheet described in [2] above, the photocurable composition (I) may include a monomer component. [4] In the pressure-sensitive adhesive sheet described in [3] above, the monomer component may include at least one selected from the group consisting of an acidic group-containing monomer and a nitrogen atom-containing monomer. [5] In the pressure-sensitive adhesive sheet described in [3] or [4] above, the photocurable composition (I) may further include a crosslinking agent. [6] In the pressure-sensitive adhesive sheet described in any of [2] to [5] above, the photocurable composition (II) may include a polyfunctional (meth)acrylate. [7] In the pressure-sensitive adhesive sheet described in any of [2] to [6] above, the photocurable composition (I) and the photocurable composition (II) may be free of an ultraviolet absorber. [8] The pressure-sensitive adhesive sheet according to any one of [2] to [7] above may be obtained by adding the photocurable composition (II) to a cured material layer formed from the photocurable composition (I) and curing the resulting mixture. [9] A method for producing a pressure-sensitive adhesive sheet according to an embodiment of the present invention is a method for producing a pressure-sensitive adhesive sheet according to any one of [2] to [8] above, the method comprising adding the photocurable composition (II) to a cured material layer formed from the photocurable composition (I) and curing the resulting mixture.

[10] An optical laminate according to an embodiment of the present invention comprises the pressure-sensitive adhesive sheet according to any one of [1] to [8] above and an optical member.

[11] An image display device according to an embodiment of the present invention comprises the optical laminate according to

[10] above.

[0007] According to an embodiment of the present invention, it is possible to provide a pressure-sensitive adhesive sheet that is suitable for suppressing damage to an image display panel due to a local load.

[0008] FIG. 1 is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention. FIG. 2 is a schematic view for explaining Test 1. FIG. 3 is a schematic view for explaining Test 2. FIG. 4 is a schematic view for explaining Test 3. FIG. 5 is a schematic view for explaining an example of a method for producing a pressure-sensitive adhesive sheet according to the present invention. FIG. 6 is a schematic view for explaining an example of a method for producing a pressure-sensitive adhesive sheet according to the present invention. FIG. 7 is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention. FIG. 8 is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention. FIG. 9 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. FIG. 10 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention.

[0009] [Terminology] In this specification, when the expression "weight" appears, it may be read as "mass," which is commonly used as an SI unit indicating weight, and vice versa.

[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 methacrolein".

[0011] In this specification, the term "monomer component" as a criterion for the content of various components in the photocurable composition means the sum of the monomer component that is not partially polymerized and that is contained in the photocurable composition, and the monomer component that is consumed in forming a partially polymerized product that can be contained in the photocurable composition.

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

[0013] In this specification, with regard to the in-plane retardation (Re), "Re(λ)" is the in-plane retardation of a film measured with light having a wavelength of λ nm at 23° C. For example, "Re(550)" is the in-plane retardation of a film measured with light having a wavelength of 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 regard to the thickness direction retardation (Rth), "Rth(λ)" is the retardation in the thickness direction of a film measured with light having a wavelength of λ nm at 23° C. For example, "Rth(550)" is the retardation in the thickness direction of a film measured with light having a wavelength of 550 nm at 23° C. Rth(λ) is calculated by the formula: Rth=(nx-nz)×d, where d (nm) is the thickness of the film.

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

[0016] When angles are referred to herein, unless otherwise specified, the angles include angles in both clockwise and counterclockwise directions.

[0017] <<1. Pressure-Sensitive Adhesive Sheet>> An example of a pressure-sensitive adhesive sheet according to an embodiment of the present invention is shown in FIG. 1 . The pressure-sensitive adhesive sheet 10 satisfies at least one of the following requirements (i) to (iii): (i) The coloring ratio X1 determined by Test 1 below satisfies X1≦1.1%. (ii) The coloring ratio X2 determined by Test 2 below satisfies X2≦1.8%. (iii) The coloring ratio X3 determined by Test 3 below satisfies X3≦4.6%. Test 1: A laminate S1 is prepared in which a glass plate, a press scale (manufactured by Fujifilm Corporation, for medium pressure (MS)), and a pressure-sensitive adhesive sheet 10 are laminated in this order. A piercing test T1 is performed using a piercing jig with a tip curvature radius R of 550 μm, in which the laminate S1 is pierced from the pressure-sensitive adhesive sheet 10 side at a piercing speed of 0.9 mm / min until a load of 0.2 kgf is reached. After the piercing test T1, the surface of the prescale is observed using an optical microscope under the conditions of a magnification of 300 times and a field of view of 840 μm × 1120 μm. 2 ) to the area A1 (μm 2 ) is specified as the coloring ratio X1 (%). Test 2: A laminate S2 is prepared by laminating a glass plate, a prescale (manufactured by Fujifilm Corporation, for medium pressure (MS)), an adhesive sheet 10, and an antireflection laminate having a thickness of 85 μm in this order. A piercing test T2 is performed in which a piercing jig with a tip curvature radius R of 550 μm is used to pierce the laminate S2 from the antireflection laminate side at a piercing speed of 0.9 mm / min until the load reaches 0.5 kgf. After the piercing test T2, the surface of the prescale is observed using an optical microscope at a magnification of 300 times and a field of view of 840 μm x 1120 μm. The area A (μm 2 ) to the area A2 (μm 2) is specified as the coloring ratio X2 (%). Test 3: A laminate S3 is prepared by laminating a glass plate, a prescale (manufactured by Fujifilm Corporation, for medium pressure (MS)), a polarizing film with a 104 μm thick retardation film, an adhesive sheet 10, and an antireflection laminate with a thickness of 85 μm in this order. A piercing test T3 is performed in which a piercing jig with a tip curvature radius R of 550 μm is used to pierce the laminate S3 from the antireflection laminate side at a piercing speed of 0.9 mm / min until the load reaches 1.0 kgf. After the piercing test T3, the surface of the prescale is observed using an optical microscope at a magnification of 300 times and a field of view of 840 μm x 1120 μm. The area A (μm 2 ) to the area A3 (μm 2 ) is specified as the coloring ratio X3 (%).

[0018] The coloring ratios X1 to X3 of the requirements (i) to (iii) can be indicators of the degree of stress dispersion by the pressure-sensitive adhesive sheet 10 when a local load is applied. A pressure-sensitive adhesive sheet 10 that satisfies at least one selected from the group consisting of the above requirements (i) to (iii) can be said to be suitable for dispersing stress when a local load is applied. Of the requirements (i) to (iii), it is particularly preferable that the pressure-sensitive adhesive sheet 10 satisfies requirement (i). The pressure-sensitive adhesive sheet 10 may also satisfy all of requirements (i) to (iii).

[0019] Requirement (i) is explained in detail below. Test 1 for determining the coloring ratio X1 can be performed by the following method. First, as shown in FIG. 2A, adhesive sheet 10 is attached to prescale 1 (manufactured by Fujifilm Corporation, for medium pressure (MS)). The thickness of prescale 1 is 100 μm. The prescale is a pressure measurement film configured to color the area where a specific pressure (10 to 50 MPa) is applied. Next, prescale 1 is brought into contact with glass plate 5 to obtain a laminate S1 composed of glass plate 5 / prescale 1 / adhesive sheet 10. The thickness of glass plate 5 is, for example, 0.5 mm or more.

[0020] Next, the laminate S1 is placed on the stage of a measuring device equipped with a piercing jig 6. The radius of curvature R of the tip of the piercing jig 6 is 550 μm. Next, a piercing test T1 is performed using the piercing jig 6 to pierce the laminate S1 from the pressure-sensitive adhesive sheet 10 side at a piercing speed of 0.9 mm / min until the load reaches 0.2 kgf. The piercing test T1 is performed, for example, in a room temperature (23°C ± 3°C) environment. In the piercing test T1, the piercing jig 6 continues to pierce the laminate S1 for 20 seconds after the load reaches 0.2 kgf, so that the load is maintained.

[0021] After the piercing test T1, the prescale 1 is removed from the laminate S1, and the surface of the prescale 1 at the position where the load was applied by the piercing jig 6 is observed with an optical microscope. Observation with the optical microscope is performed under conditions of a magnification of 300x and a field of view of 840 μm × 1120 μm. Next, the microscope image showing the field of view is converted into an HSB Stack image type using software (e.g., ImageJ), and binarized. In the binarization process, the minimum value of darkness is set to 0, the maximum value of darkness to 255, and the darkness threshold value to 30. In detail, areas of the microscope image with a darkness of less than 30 are converted into white areas (darkness 0), and areas with a darkness of 30 or more are converted into black areas (darkness 255). In this way, the areas (black areas) that were colored by the load applied to the prescale 1 in the piercing test T1 are identified, and their area (colored area) A1 (μm 2 The area A of the field of view (940800 μm 2 ) to area A1 (μm 2 ) is specified as the coloring ratio X1 (%).

[0022] The coloring ratio X1 is preferably X1≦1.1%, and may be X1≦1.0%, X1≦0.8%, X1≦0.5%, X1≦0.3%, or even X1≦0.2%. The lower limit of the coloring ratio X1 is not particularly limited, and may be, for example, X1≧0%, or X1≧0.01%.

[0023] Next, requirement (ii) will be described in detail. Test 2 for determining the coloring ratio X2 can be performed by the following method. First, as shown in FIG. 2B , one surface of the adhesive sheet 10 is bonded to a prescale 1 (manufactured by Fujifilm Corporation, for medium pressure (MS)). The thickness of the prescale 1 is 100 μm. Next, the other surface of the adhesive sheet 10 is bonded to an antireflection laminate 2 having a thickness of 85 μm. The antireflection laminate 2 is typically an AR film (AR+HC thickness: 4 μm, substrate thickness: 80 μm, total thickness: 85 μm) manufactured by Dexerials Corporation. Next, the prescale 1 is brought into contact with a glass plate 5 to obtain a laminate S2 composed of the glass plate 5 / prescale 1 / adhesive sheet 10 / antireflection laminate 2. The thickness of the glass plate 5 is, for example, 0.5 mm or more.

[0024] Next, the laminate S2 is placed on the stage of a measuring device equipped with a piercing jig 6. The radius of curvature R of the tip of the piercing jig 6 is 550 μm. Next, a piercing test T2 is performed using the piercing jig 6 to pierce the laminate S2 from the antireflection laminate 2 side at a piercing speed of 0.9 mm / min until a load of 0.5 kgf is reached. The piercing test T2 is performed, for example, in a room temperature (23°C ± 3°C) environment. In the piercing test T2, the piercing jig 6 continues to pierce the laminate S2 for 20 seconds after the load reaches 0.5 kgf, so that the load is maintained.

[0025] After the piercing test T2, the prescale 1 is removed from the laminate S2, and the surface of the prescale 1 at the position where the load was applied by the piercing jig 6 is observed with an optical microscope. Observation with the optical microscope is performed under conditions of a magnification of 300x and a field of view of 840 μm × 1120 μm. Next, the microscope image showing the field of view is converted into an HSB Stack image type using software (e.g., ImageJ), and a binarization process is performed. In the binarization process, the minimum value of darkness is set to 0, the maximum value of darkness is set to 255, and the darkness threshold is set to 30. In detail, areas of the microscope image with a darkness of less than 30 are converted into white areas (darkness 0), and areas with a darkness of 30 or more are converted into black areas (darkness 255). In this way, the areas (black areas) that were colored by the load applied to the prescale 1 in the piercing test T2 are identified, and their area (colored area) A2 (μm 2 The area A of the field of view (940800 μm 2 ) to area A2 (μm 2 ) is specified as the coloring ratio X2 (%).

[0026] The coloring ratio X2 is preferably X2≦1.8%, and may be X2≦1.5%, X2≦1.0%, X2≦0.8%, X2≦0.5%, X2≦0.3%, or even X2≦0.1%. The lower limit of the coloring ratio X2 is not particularly limited, and may be, for example, X2≧0%, or X2≧0.01%.

[0027] Next, requirement (iii) will be described in detail. Test 3 for determining the coloring ratio X3 can be performed by the following method. First, as shown in FIG. 2C , one surface of the pressure-sensitive adhesive sheet 10 is bonded to a polarizing film 3 with a retardation film having a thickness of 104 μm. A representative example of the polarizing film 3 with a retardation film is the film used in the Examples. Next, the other surface of the pressure-sensitive adhesive sheet 10 is bonded to an antireflection laminate 2 with a thickness of 85 μm. A representative example of the antireflection laminate 2 is an AR film manufactured by Dexerials Corporation (AR+HC thickness: 4 μm, substrate thickness: 80 μm, total thickness: 85 μm).

[0028] Next, a prescale 1 (manufactured by Fujifilm Corporation, for medium pressure (MS)) is placed on the opposite side of the adhesive sheet 10 to the polarizing film 3 with retardation film. The thickness of the prescale 1 is 100 μm. The polarizing film 3 with retardation film may have an adhesive sheet for bonding the polarizing film 3 with retardation film to the prescale 1. Next, the prescale 1 is brought into contact with the glass plate 5 to obtain a laminate S3 composed of the glass plate 5 / prescale 1 / polarizing film 3 with retardation film / adhesive sheet 10 / anti-reflection laminate 2. The thickness of the glass plate 5 is, for example, 0.5 mm or more.

[0029] Next, the laminate S3 is placed on the stage of a measuring device equipped with a piercing jig 6. The radius of curvature R of the tip of the piercing jig 6 is 550 μm. Next, a piercing test T3 is performed using the piercing jig 6 to pierce the laminate S3 from the antireflection laminate 2 side at a piercing speed of 0.9 mm / min until a load of 1.0 kgf is reached. The piercing test T3 is performed, for example, in a room temperature (23°C ± 3°C) environment. In the piercing test T3, the piercing jig 6 continues to pierce the laminate S3 for 20 seconds after the load reaches 1.0 kgf, so that the load is maintained.

[0030] After the piercing test T3, the prescale 1 is removed from the laminate S3, and the surface of the prescale 1 at the position where the load was applied by the piercing jig 6 is observed with an optical microscope. Observation with the optical microscope is performed under conditions of a magnification of 300x and a field of view of 840 μm × 1120 μm. Next, the microscope image showing the field of view is converted into an HSB Stack image type using software (e.g., ImageJ), and a binarization process is performed. In the binarization process, the minimum value of darkness is set to 0, the maximum value of darkness is set to 255, and the darkness threshold is set to 30. In detail, areas of the microscope image with a darkness of less than 30 are converted into white areas (darkness 0), and areas with a darkness of 30 or more are converted into black areas (darkness 255). In this way, the areas (black areas) that were colored by the load applied to the prescale 1 in the piercing test T3 are identified, and their area (colored area) A3 (μm 2 The area A of the field of view (940800 μm 2) to area A3 (μm 2 ) is specified as the coloring ratio X3 (%).

[0031] The coloring ratio X3 is preferably X3≦4.6%, and may be X3≦4.5%, X3≦4.0%, X3≦3.5%, X3≦3.0%, X3≦2.5%, X3≦2.0%, X3≦1.5%, or even X3≦1.3%. The lower limit of the coloring ratio X3 is not particularly limited, and may be, for example, X3≧0%, X3≧0.1%, or even X3≧0.5%.

[0032] The pressure-sensitive adhesive sheet 10 preferably includes a polymer P1 formed from a photocurable composition (I) and a polymer P2 formed from a photocurable composition (II) different from the photocurable composition (I). The combination of polymers P1 and P2 makes it easy to adjust the coloring ratios X1 to X3 to low values.

[0033] <1-1. Photocurable composition (I)> The photocurable composition (I) is typically a photocurable pressure-sensitive adhesive composition that cures when irradiated with light. The photocurable composition (I) cures to form a polymer P1. Note that being a photocurable composition is particularly preferred in terms of environmental protection and sustainability, since it can reduce the amount of energy required to form a pressure-sensitive adhesive sheet compared to a thermosetting composition that cures mainly using heat.

[0034] The photocurable composition (I) preferably contains a monomer component. A part of the monomer component may be a partially polymerized product. The monomer component preferably contains a (meth)acrylic monomer. That is, the photocurable composition (I) preferably contains at least one selected from the group consisting of a (meth)acrylic monomer and a partially polymerized product of the (meth)acrylic monomer.

[0035] The content of the monomer component in the photocurable composition (I) is preferably 50% by weight or more, more preferably 60% by weight or more, even more preferably 70% by weight or more, and particularly preferably 80% by weight or more.

[0036] Examples of (meth)acrylic monomers include (meth)acrylic acid alkyl esters. The (meth)acrylic acid alkyl esters may be of only one type, or may be of two or more types. The (meth)acrylic acid alkyl ester is typically a (meth)acrylic acid alkyl ester in which the alkyl group in the alkyl ester moiety has 1 to 20 carbon atoms. The number of carbon atoms in the alkyl group is preferably 1 to 12, more preferably 1 to 10, even more preferably 1 to 8, and particularly preferably 2 to 6. The alkyl group may be linear or branched. Specific examples of (meth)acrylic acid alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate, isoheptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. Examples of the (meth)acrylic acid alkyl ester include n-octyl(meth)acrylate, isooctyl(meth)acrylate, n-nonyl(meth)acrylate, isononyl(meth)acrylate, n-decyl(meth)acrylate, isodecyl(meth)acrylate, n-dodecyl(meth)acrylate (lauryl(meth)acrylate), n-tridecyl(meth)acrylate, n-tetradecyl(meth)acrylate, pentadecyl(meth)acrylate, hexadecyl(meth)acrylate, heptadecyl(meth)acrylate, and octadecyl(meth)acrylate. Among these, n-butyl(meth)acrylate is preferred as the (meth)acrylic acid alkyl ester, and n-butyl acrylate is more preferred, in terms of being able to further exhibit the effects of the present invention.

[0037] The content of the (meth)acrylic acid alkyl ester in the monomer components is preferably 40% by weight to 100% by weight, more preferably 50% by weight to 99.9% by weight, even more preferably 55% by weight to 99% by weight, and particularly preferably 60% by weight to 99% by weight. This content may be 60% by weight to 95% by weight, 65% by weight to 90% by weight, 68% by weight to 88% by weight, or 70% by weight to 85% by weight.

[0038] The monomer component preferably contains at least one selected from the group consisting of an acidic group-containing monomer and a nitrogen atom-containing monomer, and more preferably contains both an acidic group-containing monomer and a nitrogen atom-containing monomer.

[0039] The acidic group-containing monomer refers to a monomer having at least one acidic group in its structure. Examples of the acidic group-containing monomer include carboxyl group-containing monomers.

[0040] The carboxyl group-containing monomer may be one type only, or two or more types. The carboxyl group-containing monomer is a compound that contains a carboxyl group in its structure and a polymerizable unsaturated double bond such as a (meth)acryloyl group or a vinyl group. Examples of the carboxyl group-containing monomer include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid, and preferably (meth)acrylic acid, and more preferably acrylic acid.

[0041] Other examples of the acidic group-containing monomer include sulfonic acid group-containing monomers such as allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, and sulfopropyl (meth)acrylate; and phosphoric acid group-containing monomers such as 2-hydroxyethylacryloylphosphate.

[0042] The content of the acidic group-containing monomer (particularly, the carboxyl group-containing monomer) in the monomer components is preferably 0 to 10% by weight, more preferably 0.1 to 10% by weight, even more preferably 1 to 9% by weight, particularly preferably 2 to 8% by weight, and most preferably 3 to 7% by weight.

[0043] The nitrogen atom-containing monomer refers to a monomer having at least one nitrogen atom in its structure. Examples of the nitrogen atom-containing monomer include amide group-containing monomers.

[0044] The amide group-containing monomer may be one type only or two or more types. The amide group-containing monomer is a compound that contains an amide group in its structure and a polymerizable unsaturated double bond such as a (meth)acryloyl group or a vinyl group. The amide group-containing monomer is preferably an amide group-containing (meth)acrylate.

[0045] Examples of the amide group-containing monomer include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropylacrylamide, N-methyl(meth)acrylamide, N-butyl(meth)acrylamide, N-hexyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methylol-N-propane(meth)acrylamide, aminomethyl(meth)acrylamide, aminoethyl(meth)acrylamide, mercaptopropylacrylamide, methylpropane-N-propane(meth) ... Examples thereof include acrylamide-based monomers such as butylmethyl(meth)acrylamide and mercaptoethyl(meth)acrylamide; N-acryloyl heterocyclic monomers such as N-(meth)acryloylmorpholine, N-(meth)acryloylpiperidine and N-(meth)acryloylpyrrolidine; and N-vinyl group-containing lactam-based monomers such as N-vinylpyrrolidone and N-vinyl-ε-caprolactam, of which N-(meth)acryloylmorpholine is preferred, and N-acryloylmorpholine is more preferred.

[0046] Other examples of the nitrogen atom-containing monomer include alkylaminoalkyl (meth)acrylates such as aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and t-butylaminoethyl (meth)acrylate; succinimide-based monomers such as N-(meth)acryloyloxymethylene succinimide, N-(meth)acryloyl-6-oxyhexamethylene succinimide, and N-(meth)acryloyl-8-oxyoctamethylene succinimide; maleimide-based monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, and N-phenylmaleimide; and itaconimide-based monomers such as N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, and N-laurylitaconimide.

[0047] The content of the nitrogen atom-containing monomer (particularly the amide group-containing monomer) in the monomer components is, for example, 0% by weight to 50% by weight, optionally 0.1% by weight to 45% by weight, optionally 0.1% by weight to 40% by weight, optionally 0.1% by weight to 35% by weight, optionally 0.1% by weight to 30% by weight, optionally 0.1% by weight to 25% by weight, optionally 1% by weight to 20% by weight, or optionally 5% by weight to 15% by weight.

[0048] The monomer component may or may not contain a hydroxy group-containing monomer. The hydroxy group-containing monomer may be of only one type, or two or more types. Examples of the hydroxy group-containing monomer include hydroxy group-containing (meth)acrylates having 1 to 20 carbon atoms, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)-methyl acrylate. The content of the hydroxy group-containing monomer in the monomer component is preferably 0% to 20% by weight. This content may be 0% to 15% by weight, 0% to 10% by weight, 0% to 7% by weight, or 0% to 5% by weight.

[0049] The monomer component may contain an ether group-containing monomer. The ether group-containing monomer may be of only one type or of two or more types. Examples of the ether group-containing monomer include alkoxy group-containing monomers. Examples of the alkoxy group-containing monomer include alkylene oxide adducts represented by the following chemical formula (1). In chemical formula (1), R 1 is a hydrogen atom or a methyl group, and R 2 is an alkyl group. 2 R may be linear or branched, and is preferably linear. 2 Specific examples of the group are typically a methyl group and an ethyl group. n in chemical formula (1) is an integer of 1 to 30, preferably an integer of 1 to 12, and more preferably an integer of 1 to 5.

[0050] Specific examples of the alkylene oxide adduct represented by chemical formula (1) include 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, and methoxypolyethylene glycol (meth)acrylate.

[0051] The ether group-containing monomer is not limited to the alkylene oxide adduct. The ether group-containing monomer may have a ring structure, and the ring structure may have an ether group. Examples of the ring structure having an ether group include a tetrahydrofuran ring and a dioxane ring. Specific examples of the ether group-containing monomer having a ring structure include cyclic trimethylolpropane formal (meth)acrylate and tetrahydrofurfuryl (meth)acrylate.

[0052] The content of the ether group-containing monomer in the monomer component is, for example, 0 to 20% by weight, or alternatively, 0 to 15% by weight, 0 to 10% by weight, 0 to 7% by weight, or 0 to 5% by weight.

[0053] The monomer component may contain other copolymerizable monomers. The other copolymerizable monomers may be of only one type or of two or more types. Examples of the other copolymerizable monomers include acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride; caprolactone adducts of acrylic acid; vinyl-based monomers such as vinyl acetate and vinyl propionate; cyanoacrylate-based monomers such as acrylonitrile and methacrylonitrile; epoxy group-containing (meth)acrylates such as glycidyl (meth)acrylate; 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, and methoxypolypropylene glycol (meth)acrylate; Examples of the monomer include (meth)acrylates such as trihydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, and silicone (meth)acrylate; and silane monomers containing silicon atoms such as 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8-vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, and 10-acryloyloxydecyltriethoxysilane.

[0054] The content of other copolymerizable monomers in the monomer component is, for example, 0 to 10% by weight, may be 0 to 5% by weight, or may be 0 to 3% by weight.

[0055] The photocurable composition (I) may contain a partial polymer of the above-mentioned monomer component. The partial polymer may be either a homopolymer or a copolymer. The partial polymer can appropriately increase the viscosity of the photocurable composition (I), thereby contributing to the stable formation of a coating layer, which will be described later.

[0056] The photocurable composition (I) may contain a photopolymerization initiator. Any appropriate photopolymerization initiator may be used as the photopolymerization initiator as long as the effects of the present invention are not impaired. Examples of the photopolymerization initiator include photoradical generators that generate radicals when exposed to visible light and / or ultraviolet light having a wavelength shorter than 450 nm. The photopolymerization initiator may be one type or two or more types.

[0057] Examples of the photopolymerization initiator include α-ketol compounds such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, and 1-hydroxycyclohexylphenyl ketone; acetophenone compounds such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, and 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane-1; benzoin ether compounds such as benzoin ethyl ether, benzoin isopropyl ether, and anisoin methyl ether; and ketal compounds such as benzyl dimethyl ketal. aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; photoactive oxime compounds such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; benzophenone compounds such as benzophenone, benzoylbenzoic acid, and 3,3'-dimethyl-4-methoxybenzophenone; thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone; camphorquinone; halogenated ketones; acylphosphinoxides; and acylphosphonates.

[0058] The photopolymerization initiator may be a photopolymerization initiator having two or more (preferably 2 to 5) photodegradable groups. The photodegradable group refers to a functional group that absorbs irradiated active energy rays and generates radicals, and specific examples thereof include a ketone group, a halogenated alkyl group, an ester group, a sulfone group, and a peroxy group.

[0059] Examples of the photopolymerization initiator having two or more photodegradable groups include 2-hydroxy-1-[4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl]-2-methylpropan-1-one (commercially available products include, for example, the trade name "Omnirad 127D" manufactured by IGM Resins B.V.), 1-[4-(4-benzoxylphenylsulfanyl)phenyl]-2-methyl-2-(4-methylphenylsulfonyl)propan-1-one (commercially available products include, for example, the trade name "ESACURE 1001M" manufactured by IGM Resins B.V.), methyl benzoyl formate (commercially available products include, for example, the trade name "SPEEDCURE MBF" manufactured by ARKEMA), and methyl benzoyl formate (commercially available products include, for example, the trade name "SPEEDCURE MBF" manufactured by ARKEMA). Examples of commercially available products include O-ethoxyimino-1-phenylpropan-1-one (for example, a commercially available product under the trade name "SPEEDCURE PDO" manufactured by ARKEMA Sartomer), and oligo[2-hydroxy-2-methyl-4-(1-methylvinyl)phenyl]propanone (for example, a commercially available product under the trade name "ESACURE KIP150" manufactured by IGM Resins B.V.).

[0060] As the photopolymerization initiator, a compound containing a phosphorus atom and / or a nitrogen atom may be used. Examples of such photopolymerization initiators include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (commercially available products include, for example, the trade name "Omnirad 907" manufactured by IGM Resins B.V.), 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone (commercially available products include, for example, the trade name "Omnirad 369" manufactured by IGM Resins B.V.), and 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)butan-1-one (commercially available products include, for example, the trade name "Omnirad 379" manufactured by IGM Resins B.V.). B.V.), bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (a commercially available product is, for example, the trade name "Omnirad 819" manufactured by IGM Resins B.V.), 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (a commercially available product is, for example, the trade name "Omnirad TPO" manufactured by IGM Resins B.V.), 1,2-octanedione-1-[4-(phenylthio)phenyl-2-(O-benzoyloxime)] (a commercially available product is, for example, the trade name "Omnirad OXE01" manufactured by IGM Resins B.V.), B.V.), ethanone-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime) (a commercially available product is, for example, the trade name "OmniradOXE02", manufactured by IGM Resins B.V.).

[0061] The content of the photopolymerization initiator in the photocurable composition (I) may be any appropriate content as long as the effects of the present invention are not impaired. The content of such a photopolymerization initiator may be, for example, 0.02 to 10 parts by weight, 0.05 to 5 parts by weight, or even 0.1 to 1 part by weight, relative to 100 parts by weight of the monomer components.

[0062] The photocurable composition (I) may or may not contain a crosslinking agent. The crosslinking agent may be one kind or two or more kinds.

[0063] Examples of crosslinking agents include polyfunctional (meth)acrylates (such as ester compounds of polyhydric alcohols and (meth)acrylic acid), allyl (meth)acrylate, vinyl (meth)acrylate, divinylbenzene, epoxy (meth)acrylate, polyester (meth)acrylate, urethane (meth)acrylate, butyl di(meth)acrylate, and hexyl di(meth)acrylate.

[0064] Examples of the polyfunctional (meth)acrylate include difunctional (meth)acrylate, trifunctional (meth)acrylate, and polyfunctional (meth)acrylate having tetrafunctional or more.

[0065] Examples of bifunctional (meth)acrylates include (poly)ethylene glycol di(meth)acrylates such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and tetraethylene glycol di(meth)acrylate; (poly)propylene glycol di(meth)acrylates such as propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, and tetrapropylene glycol di(meth)acrylate; 1,6-hexanediol di(meth)acrylate; 1,9-nonanediol diacrylate (NDDA); 1,12-dodecanediol di(meth)acrylate; glycerin di(meth)acrylate; stearic acid-modified pentaerythritol di(meth)acrylate; dicyclopentadienyl di(meth)acrylate; di(meth)acryloyl isocyanurate; and ethoxylated bisphenol A di(meth)acrylate.

[0066] Examples of trifunctional (meth)acrylates include pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, and tris((meth)acryloyloxyethyl)isocyanurate.

[0067] Examples of tetrafunctional or higher polyfunctional (meth)acrylates include di(trimethylolpropane)tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, and alkyl-modified dipentaerythritol penta(meth)acrylate.

[0068] One preferred embodiment of the polyfunctional (meth)acrylate is 1,9-nonanediol di(meth)acrylate (for example, 1,9-nonanediol diacrylate (NDDA)) or di(trimethylolpropane)tetra(meth)acrylate. As the di(trimethylolpropane)tetra(meth)acrylate, for example, a commercially available product under the trade name "PHOTOMER 4306" (manufactured by IGM Resins B.V.) can be used.

[0069] As the epoxy (meth)acrylate, a commercially available product such as "EBECRYL3700" (manufactured by Daicel Allnex Co., Ltd.) can be used.

[0070] As the polyester (meth)acrylate, a commercially available product such as "PHOTOMER 5429" (manufactured by IGM Resins B.V.) can be used.

[0071] As the urethane (meth)acrylate, a commercially available product such as "EBECRYL4859" (manufactured by Daicel Allnex Co., Ltd.) can be used.

[0072] A polyfunctional oligomer may be used as the crosslinking agent. Only one type of polyfunctional oligomer may be used, or two or more types may be used. Examples of polyfunctional oligomers include urethane (meth)acrylate oligomers (oligomers having a urethane skeleton and two or more (meth)acryloyl groups), epoxy (meth)acrylate oligomers (oligomers having an epoxy skeleton and two or more (meth)acryloyl groups), and silicone (meth)acrylate oligomers (oligomers having a siloxane skeleton and two or more (meth)acryloyl groups). Preferably, the polyfunctional oligomer is urethane (meth)acrylate oligomer. Commercially available urethane (meth)acrylate oligomers include, for example, products manufactured by Negami Chemical Industrial Co., Ltd. under the trade names "Art Resin PMH-401B," "Art Resin UN-333," "Art Resin UN-350," "Art Resin UN-353," "Art Resin UN-5500," and "Art Resin UN-5590."

[0073] The weight average molecular weight (Mw) of the polyfunctional oligomer is, for example, 1,000 to 50,000, 5,000 to 40,000, 8,000 to 30,000, 11,000 to 25,000, 14,000 to 23,000, or 16,000 to 22,000. Such a configuration is preferable from the viewpoint of appropriately adjusting the viscoelasticity (e.g., shear storage modulus and loss tangent) of the polymer P1. The weight average molecular weight (Mw) in this specification is a value (polystyrene equivalent) based on measurement by GPC (gel permeation chromatography).

[0074] In terms of being able to further exhibit the effects of the present invention, it is preferable to select at least one crosslinking agent selected from the group consisting of polyfunctional (meth)acrylates, epoxy (meth)acrylates, polyester (meth)acrylates, urethane (meth)acrylates, and polyfunctional oligomers.

[0075] As the crosslinking agent, an isocyanate-based crosslinking agent may be used in combination with the above crosslinking agent. Such an isocyanate-based crosslinking agent may be used alone or in combination of two or more types. The content of the isocyanate-based crosslinking agent in the total amount of crosslinking agents is preferably 0% by weight to 50% by weight, more preferably 0% by weight to 30% by weight, even more preferably 0% by weight to 10% by weight, particularly preferably 0% by weight to 5% by weight, and most preferably 0% by weight to 1% by weight.

[0076] As the isocyanate-based crosslinking agent, any suitable conventionally known isocyanate-based crosslinking agent can be used. As the isocyanate-based crosslinking agent, a compound having at least two isocyanate groups (isocyanate compound) can be used. The number of isocyanate groups contained in the isocyanate compound is preferably 3 or more. The upper limit of the number of isocyanate groups is not particularly limited, and is, for example, 5. Examples of the isocyanate compound include aromatic isocyanate compounds, alicyclic isocyanate compounds, and aliphatic isocyanate compounds.

[0077] Examples of aromatic isocyanate compounds include phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, and xylylene diisocyanate.

[0078] 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.

[0079] Examples of the aliphatic isocyanate compound include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), pentamethylene diisocyanate (PDI), 1,2-propylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

[0080] Examples of the isocyanate-based crosslinking agent 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 products, biuret-modified products, allophanate-modified products, isocyanurate-modified products, carbodiimide-modified products, and urethane prepolymers obtained by adding them to polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, polyisoprene polyols, and the like.

[0081] The isocyanate-based crosslinking agent may contain at least one derivative selected from an alicyclic isocyanate compound and an aliphatic isocyanate compound. It is particularly preferable that the isocyanate-based crosslinking agent be at least one selected from the group consisting of pentamethylene diisocyanate (PDI)-based crosslinking agents (PDI and its derivatives) and hexamethylene diisocyanate (HDI)-based crosslinking agents (HDI and its derivatives). Specific examples of PDI-based crosslinking agents include isocyanurate-modified PDI. Specific examples of HDI-based crosslinking agents include isocyanurate-modified HDI and biuret-modified HDI.

[0082] The content of the crosslinking agent in the photocurable composition (I) may be appropriately set depending on the molecular weight, the number of functional groups, etc. In order to further exhibit the effects of the present invention, the content of the crosslinking agent (particularly the polyfunctional (meth)acrylate) per 100 parts by weight of the monomer component is preferably 0 to 20 parts by weight. This content may be 0.01 to 10 parts by weight, 0.01 to 7 parts by weight, 0.01 to 5 parts by weight, 0.05 to 3 parts by weight, 0.05 to 1 part by weight, or 0.05 to 0.5 parts by weight.

[0083] The photocurable composition (I) may contain any other appropriate additives as long as the effects of the present invention are not impaired. The other additives may be one kind or two or more kinds. Examples of such other additives include chain transfer agents, silane coupling agents, viscosity modifiers, tackifiers, plasticizers, softeners, antioxidants, fillers, colorants, rust inhibitors, antioxidants, antistatic agents, UV absorbers, and solvents.

[0084] In one embodiment of the photocurable composition (I), the content of the ultraviolet absorber in the photocurable composition (I) relative to 100 parts by weight of the monomer component is preferably 0 to 5 parts by weight, may be 0 to 3 parts by weight, may be 0 to 2 parts by weight, may be 0 to 1 part by weight, or may be substantially 0 part by weight.

[0085] The photocurable composition (I) may contain a solvent, and the content of the solvent in the photocurable composition (I) is preferably 5% by weight or less.

[0086] The viscosity of the photocurable composition (I) is, for example, 5 to 150 poise.

[0087] The photocurable composition (I) has a gel fraction G1 of X (%) after curing. The gel fraction G1 is preferably X≦90%, and may be X≦85%, X≦80%, X≦75%, X≦70%, or even X≦65%. The lower limit of the gel fraction G1 is not particularly limited, and may be, for example, X≧0%, X≧0.1%, X≧1.0%, X≧10%, X≧30%, X≧50%, or even X≧60%. The gel fraction G1 preferably satisfies 1.0%≦X≦90%.

[0088] The gel fraction G1 can be an index of the crosslink density of the polymer P1 in the pressure-sensitive adhesive sheet 10. In other words, the gel fraction G1 can be regarded as the gel fraction of the polymer P1 in the pressure-sensitive adhesive sheet 10. The gel fraction G1 can be measured by the following method. First, the photocurable composition (I) is sufficiently cured to form a cured product layer. Examples of the curing conditions for the photocurable composition (I) include the conditions described below in Section <1-4. Method for producing a pressure-sensitive adhesive sheet>. The curing conditions for the photocurable composition (I) are set, for example, so that the total content of the monomer component and the crosslinking agent remaining in the obtained cured product layer is 1000 wtppm or less, preferably 500 wtppm or less.

[0089] Next, a portion of the cured material layer is scraped off to obtain a small piece. The obtained small piece is then wrapped in a stretched porous polytetrafluoroethylene membrane and tied with kite string. This results in a test piece. Next, the total weight (weight A) of the cured material layer piece, the stretched porous membrane, and the kite string is measured. The total weight of the stretched porous membrane and the kite string used is defined as weight B. Next, the test piece is immersed in a container filled with ethyl acetate and left to stand at 23°C for one week. After standing, the test piece is removed from the container and dried for two hours in a dryer set at 130°C, after which the weight C of the test piece is measured. The gel fraction of the cured material layer is calculated from weight A, weight B, and weight C using the following formula. The calculated value can be considered as the gel fraction G1 of the photocurable composition (I) after curing. Gel fraction (wt%) = (C - B) / (A - B) x 100

[0090] <1-2. Photocurable composition (II)> The photocurable composition (II) is a photocurable composition that is cured by irradiation with light. When the photocurable composition (II) is cured, a polymer P2 is formed.

[0091] The photocurable composition (II) preferably contains at least one selected from the group consisting of a monomer component and a crosslinking agent. The monomer component and the crosslinking agent described in Section 1-1. Photocurable composition (I) may be used. The photocurable composition (II) preferably contains only the crosslinking agent among the monomer component and the crosslinking agent. In this embodiment, the crosslinking agent can function as a photopolymerizable compound.

[0092] When the photocurable composition (II) contains a monomer component, the monomer component may be one kind or two or more kinds. The photocurable composition (II) may contain a partial polymer of the monomer component.

[0093] The monomer component preferably contains a nitrogen atom-containing monomer (particularly an amide group-containing monomer). In the photocurable composition (II), the monomer component may contain a monomer other than the monomers described in Section 1-1. Photocurable composition (I). Examples of the other monomer include a monomer having a cyclic structure in the molecule.

[0094] Examples of monomers having a cyclic structure in the molecule include (meth)acrylic acid cycloalkyl esters such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, and cyclooctyl (meth)acrylate; (meth)acrylic acid esters having a bicyclic aliphatic hydrocarbon ring such as isobornyl (meth)acrylate; dicyclopentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, tricyclopentanyl (meth)acrylate, and 1-adamantyl (meth)acrylic acid esters having three or more aliphatic hydrocarbon rings such as (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, and 2-ethyl-2-adamantyl (meth)acrylate; (meth)acrylic acid esters having an aromatic ring such as (meth)acrylic acid aryl esters such as phenyl (meth)acrylate, (meth)acrylic acid aryloxyalkyl esters such as phenoxyethyl (meth)acrylate, and (meth)acrylic acid arylalkyl esters such as benzyl (meth)acrylate.

[0095] The content of the monomer component in the photocurable composition (II) (particularly, the content of the monomer component in the total solid content excluding the solvent) is, for example, 90% by weight or less, and may be 75% by weight or less, 50% by weight or less, 30% by weight or less, 10% by weight or less, 5% by weight or less, or even 1% by weight or less. The photocurable composition (II) may not contain a monomer component.

[0096] When the photocurable composition (II) contains a crosslinking agent, the crosslinking agent may be one kind or two or more kinds. The crosslinking agent preferably contains a polyfunctional (meth)acrylate (particularly a bifunctional (meth)acrylate).

[0097] The content of the crosslinking agent in the photocurable composition (II) (particularly, the content of the crosslinking agent in the total solid content excluding the solvent) is, for example, 10% by weight or more, and may be 25% by weight or more, 50% by weight or more, 70% by weight or more, 80% by weight or more, 90% by weight or more, or even 95% by weight or more. The upper limit of this content is not particularly limited, and may be, for example, 99% by weight or less.

[0098] The photocurable composition (II) may contain a photopolymerization initiator. As the photopolymerization initiator, those described in the section <<1-1. Photocurable composition (I)>> may be used. The photopolymerization initiator may be one type or two or more types.

[0099] The content of the photopolymerization initiator in the photocurable composition (II) may be any appropriate content within a range that does not impair the effects of the present invention. The content of such a photopolymerization initiator is, for example, 0.02 to 10 parts by weight, preferably 0.05 to 5 parts by weight, per 100 parts by weight of the total of the monomer components and the crosslinking agent.

[0100] The photocurable composition (II) may contain any other appropriate additives as long as the effects of the present invention are not impaired. Examples of the other additives include those described in Section 1-1. Photocurable composition (I). The other additives may be one type or two or more types.

[0101] In one embodiment of the photocurable composition (II), the content of the ultraviolet absorber relative to 100 parts by weight of the total of the monomer components and the crosslinking agent is preferably 0 to 5 parts by weight, may be 0 to 3 parts by weight, may be 0 to 2 parts by weight, may be 0 to 1 part by weight, or may be substantially 0 part by weight. In particular, it is preferable that the photocurable composition (I) and the photocurable composition (II) do not contain an ultraviolet absorber.

[0102] The photocurable composition (II) may contain a solvent. The solvent may be one type only, or two or more types may be used. Examples of the solvent include esters such as methyl acetate, ethyl acetate, isopropyl acetate, and butyl acetate; aromatic hydrocarbons such as toluene, xylene, and ethylbenzene; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone; aliphatic hydrocarbons such as hexane, heptane, and octane; alicyclic hydrocarbons such as cyclohexane; halogenated hydrocarbons such as chloroform, dichloromethane, and 1,2-dichloroethane; ethers such as diethyl ether, dimethoxyethane, tetrahydrofuran, and dioxane; amides such as N,N-dimethylformamide and N,N-dimethylacetamide; nitriles such as acetonitrile, propionitrile, and benzonitrile; and alcohols such as methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, sec-butanol, and tert-butanol.

[0103] The amount of the solvent may be any appropriate amount as long as it does not impair the effects of the present invention.

[0104] The total amount of the photocurable composition (II) (particularly, the total solid content excluding the solvent) relative to 100 parts by weight of the total amount of the photocurable composition (I) is, for example, 1 part by weight to 100 parts by weight, or alternatively, 3 parts by weight to 70 parts by weight, 5 parts by weight to 50 parts by weight, 7 parts by weight to 40 parts by weight, or 10 parts by weight to 30 parts by weight.

[0105] The viscosity of the photocurable composition (II) is, for example, 0.01 to 150 poise.

[0106] The photocurable composition (II) has a gel fraction G2 of Y (%) after curing. The gel fractions G1 and G2 preferably satisfy X<Y. The gel fraction G2 is preferably Y≧60%, and may be Y≧70%, Y≧80%, Y≧90%, Y≧93%, or even Y≧95%. The gel fraction G2 may be, for example, Y≦100%, or Y≦99.9%. The gel fraction G2 preferably satisfies 60%≦Y≦99.9%.

[0107] The gel fraction G2 can be an index of the crosslink density of the polymer P2 in the pressure-sensitive adhesive sheet 10. In other words, the gel fraction G2 can be regarded as the gel fraction of the polymer P2 in the pressure-sensitive adhesive sheet 10. The gel fraction G2 can be measured by the same method as the gel fraction G1, except that the photocurable composition (II) is used instead of the photocurable composition (I). Note that when the photocurable composition (II) contains a solvent, a composition having the same composition as the photocurable composition (II) except that it does not contain a solvent may be separately prepared, and the gel fraction measured using this composition may be regarded as the gel fraction G2.

[0108] <1-3. Polymers P1 and P2> As described above, the PSA sheet 10 preferably includes a polymer P1 formed from the photocurable composition (I) and a polymer P2 formed from the photocurable composition (II). In particular, the polymer P1 includes structural units derived from the monomer components and crosslinking agent contained in the photocurable composition (I). The polymer P2 includes structural units derived from the monomer components and crosslinking agent contained in the photocurable composition (II).

[0109] In the PSA sheet 10, the polymers P1 and P2 preferably exist independently of each other and may form an interpenetrating polymer network (IPN) structure or a semi-interpenetrating network (semi-IPN) structure. The interpenetrating network structure is also sometimes called a double network structure.

[0110] <<1-4. Method for producing pressure-sensitive adhesive sheet>> The pressure-sensitive adhesive sheet 10 can be produced, for example, by the following method. First, as shown in FIG. 3A , a laminate is produced that includes, in this order, a base sheet 20, a coating layer 11 containing the photocurable composition (I), and a release liner 21. This laminate can be formed, for example, by forming the coating layer 11 on the base sheet 20 (or release liner 21), and then placing the release liner 21 (or base sheet 20) on the formed coating layer 11. Alternatively, the laminate may be formed by applying the photocurable composition (I) in a poured manner into the space between the base sheet 20 and the release liner 21, which are held at a predetermined distance so that their main surfaces face each other. After forming the coating layer 11, heating and drying may be performed, if necessary.

[0111] The coating layer 11 can be formed by various coating methods such as roll coating, kiss roll coating, gravure coating, reverse coating, roll brush, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, and die coating.

[0112] The thickness of the coating layer 11 can be adjusted depending on the desired thickness of the pressure-sensitive adhesive sheet 10, and may be, for example, 500 μm or less, 250 μm or less, 150 μm or less, or even 100 μm or less. The lower limit of the thickness of the coating layer 11 may be, for example, 5 μm or more, 10 μm or more, or even 50 μm or more.

[0113] The base sheet 20 may be in the form of a sheet or a continuous sheet. Examples of the base sheet 20 include a resin film. Examples of resins constituting the resin film include polyesters such as polyethylene terephthalate, acetate resins, polyethersulfone, polycarbonate, polyamide, polyimide, polyolefin, (meth)acrylic resins, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl alcohol, polyarylate, and polyphenylene sulfide. The resin constituting the resin film is preferably a polyester such as polyethylene terephthalate.

[0114] Any appropriate thickness can be adopted as the thickness of the base sheet 20 as long as it does not impair the effects of the present invention. Such a thickness is, for example, 10 μm to 200 μm, and preferably 25 μm to 150 μm.

[0115] The substrate sheet 20 may have a release layer on the surface on the coating layer 11 side. Any appropriate release layer may be used as the release layer as long as the effects of the present invention are not impaired. For example, a commonly known release layer may be used as such a release layer. Such a release layer is typically a cured layer of a release agent composition containing a release agent. Examples of the release agent that can be used include silicone-based release agents, fluorine-based release agents, long-chain alkyl-based release agents, fatty acid amide-based release agents, and silica powder. Any appropriate thickness may be used as the release layer as long as the effects of the present invention are not impaired. Examples of such a thickness are 10 nm to 300 nm.

[0116] The substrate of the release liner 21 (hereinafter referred to as "liner substrate") can be, for example, a resin film. Examples of resins that make up the resin film include polyesters such as polyethylene terephthalate, acetate resins, polyethersulfone, polycarbonate, polyamide, polyimide, polyolefin, (meth)acrylic resins, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl alcohol, polyarylate, and polyphenylene sulfide. The resin that makes up the resin film is preferably polyesters such as polyethylene terephthalate. The thickness of the release liner 21 is, for example, 10 μm to 200 μm.

[0117] The release liner 21 may include a layer other than the liner substrate. The release liner 21 may include a release layer. The release liner 21 may include, for example, a liner substrate and a release layer formed on one surface of the liner substrate. The release layer of the release liner 21 may be on the coating layer 11 side.

[0118] Next, the laminate is irradiated with light L1. The coating layer 11 is irradiated with light L1 and cured to form a cured product layer 12 (FIG. 3B). Irradiation with light L1 is typically carried out from the side of the base sheet 20. In this case, light L1 passes through the base sheet 20 and reaches the coating layer 11, curing the coating layer 11. However, irradiation with light L1 may also be carried out from the side of the release liner 21, or from both the side of the release liner 21 and the side of the base sheet 20.

[0119] The light L1 to be irradiated may be any appropriate light under any appropriate conditions as long as the effects of the present invention are not impaired. The light L1 is, for example, visible light or ultraviolet light having a wavelength shorter than 450 nm. The light source of the light L1 may, for example, be 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, and two or more ultraviolet irradiation lamps may be combined. The illuminance of the irradiated light L1 is, for example, 1 mW / cm 2 ~20mW / cm 2 The irradiation time of the irradiated light L1 is, for example, 5 minutes to 5 hours. The integrated light amount of the irradiated light L1 is, for example, 100 mJ / cm 2 ~5000mJ / cm 2 is.

[0120] The irradiation conditions of the light L1 are not limited to those described above. For example, when a gallium-filled metal halide lamp or an LED that emits light with a wavelength of 405 nm is used as the light source of the light L1, the illuminance of the light L1 is 100 mW / cm 2 ~2000mW / cm 2 The irradiation time of the light L1 may be 1 to 2 seconds.

[0121] The cured material layer 12 contains a polymer P1 formed from the photocurable composition (I). The total content of the monomer component derived from the photocurable composition (I) and the crosslinking agent remaining in the cured material layer 12 is, for example, 1000 wtppm or less, and may be 500 wtppm or less, or even 100 wtppm or less. It is preferable that the cured material layer 12 is substantially free of the monomer component derived from the photocurable composition (I) or the crosslinking agent.

[0122] Next, as shown in Figure 3B, the release liner 21 is peeled off from the laminate to expose the surface of the cured material layer 12. A photocurable composition (II) is applied to the exposed surface of the cured material layer 12. At this time, the applied photocurable composition (II) penetrates into the cured material layer 12. This results in a precursor layer 13 of the pressure-sensitive adhesive sheet 10 (Figure 3C). Within the precursor layer 13, monomer components and crosslinking agents derived from the photocurable composition (II) are dispersed. In the manufacturing method of this embodiment, the photocurable composition (II) can be considered an additive added to the cured material layer 12.

[0123] Next, if necessary, the cured product layer 12 (precursor layer 13) coated with the photocurable composition (II) is dried. The drying of the precursor layer 13 may be carried out under any appropriate conditions as long as the effects of the present invention are not impaired. The drying temperature of the precursor layer 13 is, for example, 30°C to 200°C. The drying time of the precursor layer 13 is, for example, 1 minute to 1 hour.

[0124] 3C, a release liner 22 is then attached to the exposed surface of the precursor layer 13. This results in a laminate comprising, in this order, the base sheet 20, the precursor layer 13, and the release liner 22. As the release liner 22, the same ones as those described above for the release liner 21 can be used, and the release liner 21 itself may also be reused.

[0125] Next, the obtained laminate is irradiated with light L2. The precursor layer 13 is cured upon irradiation with the light L2 and becomes the adhesive sheet 10. Specifically, when the precursor layer 13 is irradiated with the light L2, the monomer components and crosslinking agents derived from the photocurable composition (II) react within the precursor layer 13, and the polymer P2 is formed. The irradiation with the light L2 is typically performed from the side of the base sheet 20. At this time, the light L2 passes through the base sheet 20 and reaches the precursor layer 13. However, the irradiation with the light L2 may be performed from the side of the release liner 22, or may be performed from both the side of the release liner 22 and the side of the base sheet 20. Examples of the irradiation conditions of the irradiated light L2 include those described above for the light L1.

[0126] As described above, the adhesive sheet 10 of the present embodiment is obtained, for example, by adding the photocurable composition (II) to the cured product layer 12 formed from the photocurable composition (I) and curing it. In other words, the manufacturing method of the adhesive sheet 10 of the present embodiment includes, for example, a step of adding the photocurable composition (II) to the cured product layer 12 formed from the photocurable composition (I) and curing it. However, the manufacturing method of the adhesive sheet 10 is not limited to the above. For example, the adhesive sheet 10 may be produced by adding the photocurable composition (I) to the cured product layer formed by previously curing the photocurable composition (II) and curing it.

[0127] Further, instead of the release liner 22 used in FIG. 3C, an optical member (for example, the first optical member 30 described later) may be used. In this case, an optical laminate including the adhesive sheet 10 and the optical member can be easily produced by irradiating the laminate including the base sheet 20, the precursor layer 13, and the optical member in this order with the light L2. According to this manufacturing method, the anchoring force of the adhesive sheet 10 and the optical member can be improved, and the reliability in a high-temperature environment can be improved. Similarly, instead of the base sheet 20 used in FIGS. 3A to 3C, an optical member (for example, the polarizing film 40, the second optical member 31, or the laminate of the second optical member 31 and the third optical member 3, described later) may be used

[0128] 1-5. Physical Properties of the Adhesive Sheet The gel fraction of the adhesive sheet 10 is, for example, 50% or more, and may be 75% or more, 80% or more, 85% or more, or even 90% or more.

[0129] The thickness of the pressure-sensitive adhesive sheet 10 is, for example, 500 μm or less, and may be 250 μm or less, 150 μm or less, or even 100 μm or less. The lower limit of the thickness of the pressure-sensitive adhesive sheet 10 is, for example, 1 μm or more, and may be 5 μm or more, 10 μm or more, or even 50 μm or more.

[0130] The Young's modulus of the pressure-sensitive adhesive sheet 10 is, for example, 0.2 MPa or more, and may be 0.3 MPa or more, 0.4 MPa or more, 0.6 MPa or more, 0.8 MPa or more, 1.0 MPa or more, 1.2 MPa or more, 1.5 MPa or more, 2.0 MPa or more, 5.0 MPa or more, 10 MPa or more, 15 MPa or more, or even 20 MPa or more. The upper limit of the Young's modulus of the pressure-sensitive adhesive sheet 10 is, for example, 2 GPa or less, and may be 1 GPa or less, 100 MPa or less, or even 50 MPa or less. The Young's modulus of the pressure-sensitive adhesive sheet 10 can be calculated from the stress-strain curve measured when a string-shaped sample of the pressure-sensitive adhesive sheet 10 is prepared and pulled at a rate of 50 mm / min using a tensile tester.

[0131] <<1-6. Modified Examples of Adhesive Sheets>> The adhesive sheet 10 according to the embodiment of the present invention is not limited to the single-layer adhesive sheet (adhesive sheet 10a) shown in Fig. 1. As shown in Fig. 4A, the adhesive sheet 10 according to the modified example (adhesive sheet 10b) may be a double-sided adhesive sheet including, in this order, a first adhesive portion 16, a substrate (substrate A) 15, and a second adhesive portion 17. As shown in Fig. 4B, the adhesive sheet 10 according to another modified example (adhesive sheet 10c) may be a double-sided adhesive sheet including, in this order, a first adhesive portion 16, a substrate (substrate A) 15, a second adhesive portion 17, a substrate (substrate B) 19, and a third adhesive portion 18.

[0132] The first adhesive portion 16 is preferably in a sheet form, and the description of the adhesive sheet 10a may be applied thereto. However, the first adhesive portion 16 may use a known adhesive. Similarly, the second adhesive portion 17 and the third adhesive portion 18 are preferably in a sheet form, and the description of the adhesive sheet 10a may be applied thereto. However, the second adhesive portion 17 and the third adhesive portion 18 may use a known adhesive.

[0133] Specific examples of the material that forms the main component of the substrate (substrate A) 15 include, for example, the same materials that form the main component of the protective layer described below in Section <2-9-b. Protective Layer> (transparent resins, thermosetting resins or UV-curable resins, glassy polymers, and resin compositions). Similarly, specific examples of the material that forms the main component of the substrate (substrate B) 19 include, for example, the same materials that form the main component of the protective layer described below in Section <2-9-b. Protective Layer>. In one embodiment of the present invention, at least one of the substrate (substrate A) 15 and the substrate (substrate B) 19 contains a (meth)acrylic resin, preferably a (meth)acrylic resin having a glutarimide structure. Both the substrate (substrate A) 15 and the substrate (substrate B) 19 may contain a (meth)acrylic resin, or may contain a (meth)acrylic resin having a glutarimide structure.

[0134] Optical Laminate An optical laminate according to an embodiment of the present invention includes, for example, the above-described pressure-sensitive adhesive sheet 10 and an optical member. The optical laminate is used by being attached to, for example, an image display panel. The optical laminate may be disposed on the viewing side of the image display panel, or on the light source side of the image display panel (opposite the viewing side).

[0135] <2-1. Overall configuration of optical laminate> Fig. 5 is a schematic cross-sectional view of a representative optical laminate according to an embodiment of the present invention. The optical laminate 100 shown in Fig. 5 includes a first optical member 30 and a first adhesive sheet 10A. The optical laminate 100 can be attached to an image display panel by the first adhesive sheet 10A. The optical laminate 100 can correspond to the laminate in Fig. 1 in which the adhesive sheet 10a is attached to the first optical member 30.

[0136]

[0033] Fig. 6 is a schematic cross-sectional view of another representative optical laminate according to an embodiment of the present invention. The optical laminate 110 shown in Fig. 6 includes a first optical member 30, a first adhesive sheet 10A, a second optical member 31, and a second adhesive sheet 10B, in this order. In the optical laminate 110, the first optical member 30 and the second optical member 31 are bonded together via the first adhesive sheet 10A. The optical laminate 110 can be attached to an image display panel via the second adhesive sheet 10B. The optical laminate 110 may correspond to the laminate in Fig. 4A in which the adhesive sheet 10b is bonded to the first optical member 30. Specifically, the first adhesive sheet 10A may correspond to the first adhesive portion 16 of the adhesive sheet 10b, the second optical member 31 may correspond to the substrate (substrate A) 15 of the adhesive sheet 10b, and the second adhesive sheet 10B may correspond to the second adhesive portion 17 of the adhesive sheet 10b.

[0137] FIG. 7 is a schematic cross-sectional view of another representative optical laminate according to an embodiment of the present invention. The optical laminate 120 shown in FIG. 7 includes a first optical member 30, a first adhesive sheet 10A, a second optical member 31, a second adhesive sheet 10B, a third optical member 32, and a third adhesive sheet 10C, in this order. In the optical laminate 120, the first optical member 30 and the second optical member 31 are bonded together via the first adhesive sheet 10A. The second optical member 31 and the third optical member 32 are bonded together via the second adhesive sheet 10B. The optical laminate 120 can be attached to an image display panel using the third adhesive sheet 10C. Note that in the optical laminate 120, any appropriate adhesive layer may be used instead of the second adhesive sheet 10B. The optical laminate 120 may correspond to the laminate in which the adhesive sheet 10c in FIG. 4B is bonded to the first optical member 30. Specifically, the first adhesive sheet 10A may correspond to the first adhesive portion 16 of the adhesive sheet 10c, the second optical member 31 may correspond to the base material (base material A) 15 of the adhesive sheet 10c, the second adhesive sheet 10B may correspond to the second adhesive portion 17 of the adhesive sheet 10c, the third optical member 32 may correspond to the base material (base material B) 19 of the adhesive sheet 10c, and the third adhesive sheet 10C may correspond to the third adhesive portion 18 of the adhesive sheet 10c.

[0138] 8 is a schematic cross-sectional view of another representative optical laminate according to an embodiment of the present invention. The optical laminate 130 shown in FIG. 8 includes a first optical member 30, a first adhesive sheet 10A, and a polarizing film 40, in this order. The first optical member 30 and the polarizing film 40 are bonded together via the first adhesive sheet 10A. The optical laminate 130 may further include a first retardation film 50 and a second retardation film 60, in this order from the polarizing film 40 side, on the opposite side of the first optical member 30 with respect to the polarizing film 40. The optical laminate 130 may further include a fourth adhesive sheet 10D arranged on the opposite side of the first retardation film 50 with respect to the second retardation film 60. The optical laminate 130 can be attached to an image display panel by the fourth adhesive sheet 10D. 8 includes, in this order, a first optical member 30, a first adhesive sheet 10A, a polarizing film 40, a first retardation film 50, a second retardation film 60, and a fourth adhesive sheet 10D. For convenience, the polarizing film and the retardation film are described in this specification as being distinct from the first optical member, but these are also types of optical members.

[0139] In the optical laminate 130, the configurations of the first optical member 30 and the first adhesive sheet 10A are the same as those of the optical laminate 100 in Fig. 5. Instead of the above configuration (configuration of the first optical member 30 / first adhesive sheet 10A), the optical laminate 130 may have the configuration of the optical laminate 110 in Fig. 6 (configuration of the first optical member 30 / first adhesive sheet 10A / second optical member 31 / second adhesive sheet 10B), or the configuration of the optical laminate 120 in Fig. 7 (configuration of the first optical member 30 / first adhesive sheet 10A / second optical member 31 / second adhesive sheet 10B / third optical member 32 / third adhesive sheet 10C).

[0140] The optical laminate according to an embodiment of the present invention may have any suitable configuration as long as it includes an optical member and the pressure-sensitive adhesive sheet 10 described in the section <<1. Pressure-sensitive adhesive sheet>>. Representative examples include the configurations shown in FIGS. 5 to 8, with the configuration shown in FIG. 5 being particularly preferred. The configuration shown in FIG. 5 (the configuration of the first optical member 30 / first pressure-sensitive adhesive sheet 10A) can reduce the number of components, which can be advantageous from the standpoint of cost and the environment. For example, the configuration shown in FIG. 5 is preferred because it requires fewer lamination steps for the optical laminate.

[0141] The total thickness of the optical laminate according to the embodiment of the present invention is preferably 50 μm or more, more preferably 100 μm to 500 μm, even more preferably 150 μm to 400 μm, and particularly preferably 150 μm to 300 μm.

[0142] The components of the optical laminate will be described below.

[0143] <<2-2. First Pressure-Sensitive Adhesive Sheet>> The first pressure-sensitive adhesive sheet is preferably the pressure-sensitive adhesive sheet 10 described in the section <<1. Pressure-Sensitive Adhesive Sheet>>. The thickness of the first pressure-sensitive adhesive sheet is preferably 5 μm to 400 μm, 5 μm to 300 μm, or 5 μm to 200 μm, more preferably 5 μm to 170 μm, even more preferably 5 μm to 150 μm, particularly preferably 5 μm to 130 μm, and most preferably 5 μm to 110 μm. In some cases, the thickness of the first pressure-sensitive adhesive sheet may be 5 μm to 20 μm, 5 μm to 17 μm, 5 μm to 16 μm, 5 μm to 15 μm, or even 5 μm to 14 μm.

[0144] <<2-3. Second Adhesive Sheet>> As the second adhesive sheet, any appropriate adhesive sheet can be adopted as long as the effects of the present invention are not impaired. The second adhesive sheet may be the adhesive sheet 10 described in the section <<1. Adhesive Sheet>>>, or may be one using a known adhesive.

[0145] The thickness of the second pressure-sensitive adhesive sheet is preferably 5 μm to 20 μm, more preferably 5 μm to 17 μm, even more preferably 5 μm to 16 μm, particularly preferably 5 μm to 15 μm, and most preferably 5 μm to 14 μm. In some cases, the thickness of the second pressure-sensitive adhesive sheet may be 5 μm to 400 μm, 5 μm to 300 μm, 5 μm to 200 μm, 5 μm to 170 μm, 5 μm to 150 μm, 5 μm to 130 μm, 5 μm to 110 μm, or even 40 μm to 100 μm.

[0146] <<2-4. Third Adhesive Sheet>> As the third adhesive sheet, any appropriate adhesive sheet can be adopted as long as the effects of the present invention are not impaired. The third adhesive sheet may be the adhesive sheet 10 described in the section <<1. Adhesive Sheet>>>, or may be one using a known adhesive.

[0147] The thickness of the third pressure-sensitive adhesive sheet is preferably 5 μm to 20 μm, more preferably 5 μm to 17 μm, even more preferably 5 μm to 16 μm, particularly preferably 5 μm to 15 μm, and most preferably 5 μm to 14 μm. In some cases, the thickness of the third pressure-sensitive adhesive sheet may be 5 μm to 400 μm, 5 μm to 300 μm, 5 μm to 200 μm, 5 μm to 170 μm, 5 μm to 150 μm, 5 μm to 130 μm, 5 μm to 110 μm, or even 40 μm to 100 μm.

[0148] <<2-5. Fourth Adhesive Sheet>> As the fourth adhesive sheet, any appropriate adhesive sheet can be adopted as long as the effects of the present invention are not impaired. The fourth adhesive sheet may be the adhesive sheet 10 described in the section <<1. Adhesive Sheet>>>, or may be one using a known adhesive.

[0149] The thickness of the fourth pressure-sensitive adhesive sheet is preferably 1 μm to 60 μm, and more preferably 5 μm to 30 μm. In some cases, the thickness of the fourth pressure-sensitive adhesive sheet may be 5 μm to 400 μm, 5 μm to 300 μm, 5 μm to 200 μm, 5 μm to 170 μm, 5 μm to 150 μm, 5 μm to 130 μm, 5 μm to 110 μm, or even 40 μm to 100 μm. In one embodiment of the present invention ( FIG. 8 ), the optical laminate includes a fourth pressure-sensitive adhesive sheet, but the optical laminate does not necessarily include a fourth pressure-sensitive adhesive sheet.

[0150] 2-6. First Optical Member Any appropriate optical member can be used as the first optical member as long as the effects of the present invention are not impaired. Examples of the first optical member include a cover glass, a thin glass, a protective film, an anti-reflection laminate, and a laminate for preventing sunglasses.

[0151] The thickness of the first optical member is, for example, 1 μm to 1000 μm, and may be 10 μm to 500 μm, 20 μm to 200 μm, 40 μm to 120 μm, or even 70 μm to 100 μm.

[0152] One embodiment of the first optical member is thin glass. In this specification, thin glass refers to an extremely thin glass film having a thickness of 200 μm or less. Thin glass obtained by any appropriate manufacturing method can be used. Typically, thin glass is produced by melting a mixture containing a main raw material such as silica or alumina, an antifoaming agent such as mirabilite or antimony oxide, and a reducing agent such as carbon at a temperature of 1400°C to 1600°C, forming the mixture into a thin plate, and then cooling it.

[0153] Examples of methods for forming thin glass include the slot downdraw method, the fusion method, and the float method. Among these, thin glass formed by the fusion method does not require polishing treatment because the surface is not contaminated with tin or the like as in the case of glass formed by the float method, and it is possible to ensure surface smoothness and thinness. From these viewpoints, it is preferable to use the fusion method.

[0154] The thickness of the thin glass is preferably 10 μm to 200 μm, more preferably 20 μm to 150 μm, and particularly preferably 30 μm to 100 μm.

[0155] Another embodiment of the first optical member is a protective film. Specific examples of the material that serves as the main component of the protective film include the same materials that serve as the main components of the protective layer described below in Section <2-9-b. Protective Layer> (transparent resins, thermosetting or ultraviolet-curing resins, glassy polymers, and resin compositions). In one embodiment of the present invention, the protective film contains a polyester resin such as polyethylene terephthalate (PET). The protective film may be subjected to a surface treatment described below in Section <2-9-b. Protective Layer>.

[0156] Another embodiment of the first optical member is an antireflection laminate. The antireflection laminate typically includes a first substrate, a hard coat layer disposed on the first substrate, and an antireflection layer disposed on the hard coat layer. The hard coat layer may be formed directly on the viewer-side surface of the first substrate. The antireflection layer may be formed directly on the viewer-side surface of the hard coat layer. The antireflection laminate may be a member having a laminated structure of antireflection layer / hard coat layer / first substrate. The antireflection laminate has a first substrate laminated with a first pressure-sensitive adhesive sheet.

[0157] <2-6-a. First Substrate> The first substrate is typically used to form a hard coat layer and an anti-reflection layer. Any appropriate resin film can be used as the first substrate. Examples of materials for forming the first substrate include polyester-based resins such as polyethylene terephthalate (PET), cycloolefin-based resins such as norbornene-based resins, resins (COC) obtained by addition polymerization of cycloolefins (e.g., norbornene) and α-olefins (e.g., ethylene), and cellulose-based resins such as triacetyl cellulose (TAC). One embodiment of the first substrate includes a cellulose-based resin such as TAC.

[0158] The thickness of the first substrate can be appropriately set depending on the purpose. The thickness of the first substrate is typically 20 μm to 200 μm, preferably 50 μm to 150 μm, and more preferably 70 μm to 90 μm.

[0159] <2-6-b. Hard Coat Layer> The hard coat layer can impart, for example, excellent pencil hardness to the optical laminate. Furthermore, by appropriately adjusting the difference in refractive index between the hard coat layer and the antireflection layer, the reflectance of the optical laminate can be further reduced.

[0160] The hard coat layer preferably has sufficient surface hardness, excellent mechanical strength, and excellent light transmittance. The hard coat layer can be formed from any appropriate resin as long as it has such desired properties. Specific examples of the resin include thermosetting resins, thermoplastic resins, ultraviolet curing resins, electron beam curing resins, and two-component mixed resins. Among the resins that form the hard coat layer, ultraviolet curing resins are preferred. When the resin is an ultraviolet curing resin, the hard coat layer can be formed with simple operation and high efficiency.

[0161] Specific examples of UV-curable resins include polyester-based, acrylic-based, urethane-based, amide-based, silicone-based, and epoxy-based UV-curable resins. UV-curable resins include UV-curable monomers, oligomers, and polymers. Preferred UV-curable resins include resin compositions containing acrylic monomer or oligomer components having preferably two or more, and more preferably three to six, UV-polymerizable functional groups. Typically, UV-curable resins contain a photopolymerization initiator.

[0162] The hard coat layer can be formed by any appropriate method. For example, the hard coat layer can be formed by coating a resin composition for forming a hard coat layer on a first substrate, drying the coating, and curing the dried coating film by irradiating it with ultraviolet light.

[0163] The thickness of the hard coat layer is, for example, 0.5 μm to 20 μm, and preferably 1 μm to 15 μm.

[0164] Details of the hard coat layer and the adhesion structure between the hard coat layer and the antireflection layer are described in, for example, JP 2016-224443 A, the disclosure of which is incorporated herein by reference.

[0165] <2-6-c. Antireflection Layer> The antireflection layer is provided to prevent reflection of external light (e.g., fluorescent light) and the like. Any appropriate configuration can be adopted as the configuration of the antireflection layer. Typical configurations of the antireflection layer include, for example, (1) a single layer of a low refractive index layer having an optical film thickness of 120 nm to 140 nm and a refractive index of about 1.35 to 1.55; (2) a laminate having, from the first substrate, a medium refractive index layer, a high refractive index layer, and a low refractive index layer in this order; and (3) an alternating multilayer laminate of a high refractive index layer and a low refractive index layer.

[0166] Materials that can form the low-refractive-index layer include, for example, silicon oxide (SiO2) and magnesium fluoride (MgF2). The refractive index of the low-refractive-index layer is typically approximately 1.35 to 1.55. Materials that can form the high-refractive-index layer include, for example, titanium oxide (TiO2), niobium oxide (Nb2O3 or Nb2O5), tin-doped indium oxide (ITO), antimony-doped tin oxide (ATO), and ZrO2-TiO2. The refractive index of the high-refractive-index layer is typically approximately 1.60 to 2.20. Materials that can form the medium-refractive-index layer include, for example, titanium oxide (TiO2) and a mixture of a material that can form a low-refractive-index layer and a material that can form a high-refractive-index layer (e.g., a mixture of titanium oxide and silicon oxide). The refractive index of the medium-refractive-index layer is typically approximately 1.50 to 1.85. The thicknesses of the low-refractive-index layer, medium-refractive-index layer, and high-refractive-index layer can be set to achieve an appropriate optical film thickness depending on the layer structure of the anti-reflection layer, the desired anti-reflection performance, etc.

[0167] The antireflection layer is typically formed by a dry process. Specific examples of the dry process include PVD (Physical Vapor Deposition) and CVD (Chemical Vapor Deposition). PVD methods include vacuum deposition, reactive vapor deposition, ion beam assisted deposition, sputtering, and ion plating. CVD methods include plasma CVD. The dry process for forming the antireflection layer is preferably sputtering.

[0168] The thickness of the antireflection layer is, for example, about 20 nm to 300 nm.

[0169] The difference between the maximum reflectance and the minimum reflectance of the antireflection layer in the wavelength range of 400 nm to 700 nm is preferably 2.0% or less, more preferably 1.9% or less, and even more preferably 1.8% or less. If the difference between the maximum reflectance and the minimum reflectance is in this range, coloring of reflected light can be effectively prevented.

[0170] The antireflection layer is typically located on the outermost surface of the optical laminate on the viewing side. The moisture permeability of the antireflection layer is typically 1.0 g / mm 2 or less, preferably 0.01 g / mm 2 ~0.1g / mm 2 The moisture permeability is measured in accordance with the moisture permeability test (cup method) of JIS Z0208 (for example, JIS Z0208:1976) in an atmosphere at a temperature of 40°C and a humidity of 92% RH, over an area of ​​1 m 2 When the moisture permeability of the antireflection layer located on the outermost surface is equal to or less than the upper limit, warping of the optical layered body in a high-humidity environment can be stably suppressed.

[0171] The antireflection layer does not have to be located on the outermost surface of the optical laminate. The antireflection laminate may have an outermost layer on the viewing side of the antireflection layer, if necessary. That is, the antireflection laminate may be composed of a first substrate, a hard coat layer, an antireflection layer, and an outermost layer. The moisture permeability range of the outermost layer is the same as that of the antireflection layer described above. Examples of the outermost layer include an antifouling layer. The antifouling layer contains, for example, a fluorine group-containing silane-based compound (e.g., an alkoxysilane compound having a perfluoropolyether group) or a fluorine group-containing organic compound. The antifouling layer preferably exhibits water repellency with a water contact angle of 110 degrees or more.

[0172] 2-7. Second Optical Member Any appropriate optical member can be used as the second optical member as long as the effects of the present invention are not impaired. Examples of the second optical member include thin glass, protective films, functional films, and laminates thereof.

[0173] The thickness of the second optical member is, for example, 10 μm to 500 μm, and may be 10 μm to 400 μm, 10 μm to 300 μm, 10 μm to 200 μm, 20 μm to 70 μm, or even 30 μm to 50 μm.

[0174] One embodiment of the second optical member is thin glass. Examples of thin glass include those described in the section <<2-6. First Optical Member>>.

[0175] Another embodiment of the second optical member is a protective film. Examples of the protective film include those described in Section 2-6. First Optical Member. In one embodiment of the present invention, the protective film serving as the second optical member contains a (meth)acrylic resin, and preferably contains a (meth)acrylic resin having a glutarimide structure.

[0176] Another embodiment of the second optical member is a functional film, such as a brightness enhancement film or a touch sensor film.

[0177] <2-8. Third Optical Member> Any appropriate optical member can be used as the third optical member as long as the effects of the present invention are not impaired. Examples of the third optical member include an anti-glare laminate and an anti-sunglasses laminate.

[0178] The thickness of the third optical member is typically 20 μm to 60 μm, and preferably 30 μm to 50 μm.

[0179] One embodiment of the third optical member is an anti-glare laminate. The anti-glare laminate includes an anti-glare layer and a second substrate arranged on the viewing side of the anti-glare layer. The anti-glare layer is supported on the second substrate. The anti-glare layer is in contact with a third pressure-sensitive adhesive sheet and is pressure-sensitively adhered to the third pressure-sensitive adhesive sheet. The second substrate is located on the opposite side of the anti-glare layer from the third pressure-sensitive adhesive sheet. The second substrate is in contact with the second pressure-sensitive adhesive sheet and is pressure-sensitively adhered to the second pressure-sensitive adhesive sheet.

[0180] <2-8-a. Anti-glare Layer> The anti-glare layer is provided to prevent reflections of the face of a user of the image display device, the keyboard of the image display device, external light (e.g., fluorescent light), etc. In one embodiment of the present invention, the anti-glare layer is a layer of a liquid crystal compound with a fixed orientation. In this specification, the term "fixed orientation layer" refers to a layer in which the liquid crystal compound is oriented in a predetermined direction within the layer and the orientation state is fixed. The term "fixed orientation layer" encompasses a concept that includes a hardened orientation layer obtained by hardening a liquid crystal monomer. The liquid crystal compound may be a rod-shaped liquid crystal compound, a discotic (discotic) liquid crystal compound, or a combination thereof.

[0181] In one embodiment of the present invention, the anti-glare layer contains a discotic liquid crystal compound. More specifically, the anti-glare layer is a layer in which a discotic liquid crystal compound is fixed in a state where it is aligned in a predetermined direction. A discotic liquid crystal compound generally refers to a liquid crystal compound having a discotic molecular structure in which a cyclic mother nucleus such as benzene, 1,3,5-triazine, or calixarene is located at the center of the molecule and linear alkyl groups, alkoxy groups, substituted benzoyloxy groups, or the like are radially substituted as side chains. Representative examples of discotic liquid crystals include benzene derivatives, triphenylene derivatives, truxene derivatives, and phthalocyanine derivatives described in the research report by C. Destrade et al., Mol. Cryst. Liq. Cryst., Vol. 71, p. 111 (1981), and compounds described in the research report by B. Kohne et al., Angew. Chem. 96, p. 70 (1984), and azacrown-based and phenylacetylene-based macrocycles described in the research report by J. M. Lehn et al., J. Chem. Soc. Chem. Commun., p. 1794 (1985), and the research report by J. Zhang et al., J. Am. Chem. Soc., vol. 116, p. 2655 (1994). Further specific examples of discotic liquid crystal compounds include compounds described in JP-A-2006-133652, JP-A-2007-108732, JP-A-2010-244038, and JP-A-2014-214177. The descriptions in the above-mentioned documents and publications are incorporated herein by reference. The anti-glare layer containing a discotic liquid crystal compound can typically be a so-called negative A plate having refractive index characteristics of nx=nz>ny.

[0182] In another embodiment, the anti-glare layer contains a rod-shaped liquid crystal compound. More specifically, the anti-glare layer is oriented (homogeneous orientation) in a state where the rod-shaped liquid crystal compound is aligned in a predetermined direction (typically, the slow axis direction). Examples of rod-shaped liquid crystal compounds include liquid crystal compounds having a nematic liquid crystal phase (nematic liquid crystals). Examples of such liquid crystal compounds that can be used include liquid crystal polymers and liquid crystal monomers. The mechanism by which the liquid crystal compound exhibits liquid crystallinity may be either lyotropic or thermotropic. The liquid crystal polymer and liquid crystal monomer may be used alone or in combination. Any appropriate liquid crystal monomer may be used as the liquid crystal monomer. For example, polymerizable mesogenic compounds described in JP-A-2002-533742 (WO 00 / 37585), EP 358208 (US Pat. No. 5,211,877), EP 66137 (US Pat. No. 4,388,453), WO 93 / 22397, EP 0,261,712, DE 19,504,224, DE 4,408,171, and GB 2,280,445 can be used. Specific examples of such polymerizable mesogenic compounds include LC242 (product name) from BASF, E7 (product name) from Merck, and LC-Silicon-CC3767 (product name) from Wacker-Chem. Nematic liquid crystal monomers are preferred as liquid crystal monomers. Specific examples of liquid crystal compounds are described in JP-A-2006-163343, for example. The disclosures of these publications are incorporated herein by reference. The anti-glare layer containing a rod-like liquid crystal compound can be typically a so-called positive A plate having refractive index characteristics of nx>ny=nz.

[0183] The anti-glare layer can typically function as a λ / 2 plate. When the anti-glare layer functions as a λ / 2 plate, glare can be effectively prevented by controlling its orientation angle (or slow axis direction). The in-plane retardation Re(550) of such an anti-glare layer is 220 nm to 320 nm, more preferably 240 nm to 300 nm, and even more preferably 250 nm to 280 nm.

[0184] The angle formed by the slow axis of the anti-glare layer and the absorption axis of the polarizer is preferably 35° to 55°, more preferably 40° to 50°, and even more preferably about 45°. By arranging the anti-glare layer, which functions as a λ / 2 plate, at such an axial angle, it is possible to effectively prevent glare.

[0185] The thickness of the anti-glare layer is preferably 1 μm to 5 μm, and more preferably 1 μm to 3 μm.

[0186] When an alignment film is used to align the liquid crystal compound, the anti-glare laminate further includes an alignment film between the anti-glare layer and the second substrate. That is, the anti-glare laminate may be composed of an anti-glare layer, an alignment film, and a second substrate. The alignment film generally contains a polymer material as a main component. Typical examples of polymer materials include polyvinyl alcohol, polyimide, and derivatives thereof. In one embodiment of the present invention, modified or unmodified polyvinyl alcohol is preferred. For example, modified polyvinyl alcohols described in WO 01 / 88574 A1 and Japanese Patent No. 3907735 can be used as the alignment film. The alignment film is typically subjected to an alignment treatment. Typical examples of alignment treatments include rubbing treatment and photoalignment treatment. Since rubbing treatments are well known in the art, a detailed description thereof will be omitted. Examples of the photo-aligned alignment film (photo-alignment film) that can be used include those described in WO2005 / 096041 and a product manufactured by Rolic Technologies under the trade name LPP-JP265CP. The thickness of the alignment film is, for example, 0.01 μm to 10 μm, preferably 0.01 μm to 1 μm, and more preferably 0.01 μm to 0.5 μm.

[0187] The anti-glare layer can be formed, for example, by the following procedure. First, a coating liquid for forming an alignment film is applied to a second substrate and dried to form a coating film. This coating film is rubbed in a predetermined direction to form an alignment film on the second substrate. This predetermined direction may correspond to the slow axis direction of the resulting anti-glare layer. Next, a coating liquid for forming an anti-glare layer (e.g., a solution containing a liquid crystal compound and, if necessary, a crosslinkable monomer) is applied to the formed alignment film and heated. Heating removes the solvent from the coating liquid and promotes alignment of the liquid crystal compound. Heating can be performed in a single step or in multiple steps at different temperatures. Next, ultraviolet light is irradiated to crosslink (or polymerize) the crosslinkable (or polymerizable) monomer, thereby fixing the alignment of the liquid crystal compound. In this way, an anti-glare layer is formed on the second substrate (essentially, on the alignment film). A method for aligning discotic liquid crystal compounds is described, for example, in JP 2014-214177 A, and a method for aligning rod-shaped liquid crystal compounds is described, for example, in JP 2006-163343 A. The descriptions in these publications are incorporated herein by reference. The alignment film may be omitted depending on the desired alignment state, the type of liquid crystal compound, and the like.

[0188] <2-8-b. Second Substrate> The second substrate can be used to form an anti-glare layer.

[0189] Any appropriate resin film can be used as the second substrate. Examples of materials for forming the resin film include polyester-based resins such as polyethylene terephthalate (PET), cycloolefin-based resins such as norbornene-based resins, resins (COC) obtained by addition polymerization of cycloolefins (e.g., norbornene) and α-olefins (e.g., ethylene), and cellulose-based resins such as triacetyl cellulose (TAC). In one embodiment of the present invention, the second substrate includes a cellulose-based resin such as TAC.

[0190] The thickness of the second substrate can be appropriately set depending on the purpose. The thickness of the second substrate is typically 20 μm to 200 μm, preferably 25 μm to 100 μm, and more preferably 30 μm to 50 μm.

[0191] <2-9. Polarizing Film> A polarizing film typically includes a polarizer and a protective layer disposed on the viewing side of the polarizer. The protective layer is typically attached to the polarizer via any appropriate pressure-sensitive adhesive layer. That is, the polarizing film may be composed of a polarizer, a pressure-sensitive adhesive layer, and a protective layer.

[0192] 8, the protective layer is located between the polarizer and the first adhesive sheet 10A and is in contact with the first adhesive sheet 10A. The protective layer may be pressure-sensitively adhered to the first adhesive sheet 10A. The polarizing film may further include a second protective layer, and the polarizer may be located between the protective layer and the second protective layer.

[0193] <2-9-a. Polarizer> Any appropriate polarizer can be used as the polarizer. For example, the resin film forming the polarizer may be a single-layer resin film or a laminate of two or more layers.

[0194] A specific example of a polarizer composed of a single-layer resin film is a PVA-based resin film that has been subjected to a dyeing treatment with iodine and a stretching treatment (typically, uniaxial stretching). Dyeing with iodine is performed, for example, by immersing the PVA-based resin film in an iodine aqueous solution. The stretching ratio is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment or while dyeing. Alternatively, the film may be dyed after stretching. If necessary, the PVA-based resin film may be subjected to a swelling treatment, a crosslinking treatment, a washing treatment, a drying treatment, or the like. For example, by immersing the PVA-based resin film in water and washing it before dyeing, it is possible to clean off stains and antiblocking agents on the surface of the PVA-based resin film and also to swell the PVA-based resin film, thereby preventing uneven dyeing and the like.

[0195] Specific examples of polarizers composed of a laminate of two or more layers include a polarizer composed of a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a polarizer composed of a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate. A polarizer composed of a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be produced, for example, by applying a PVA-based resin solution to the resin substrate and drying the solution to form a PVA-based resin layer on the resin substrate, thereby obtaining a laminate of the resin substrate and the PVA-based resin layer, and then stretching and dyeing the laminate to form the PVA-based resin layer into a polarizer. In a preferred embodiment, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is formed on one side of the resin substrate. Stretching typically involves immersing the laminate in an aqueous boric acid solution to stretch it. Furthermore, the stretching may further include, if necessary, in-air stretching of the laminate at a high temperature (e.g., 95°C or higher) before stretching in the boric acid aqueous solution. In addition, in a preferred embodiment, the laminate is subjected to a drying shrinkage treatment in which the laminate is heated while being transported in the longitudinal direction, thereby shrinking the laminate by 2% or more in the width direction. Typically, the laminate is subjected to an in-air auxiliary stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment, in this order. By introducing auxiliary stretching, it is possible to increase the crystallinity of the PVA, even when the PVA is coated on a thermoplastic resin, thereby achieving high optical properties. Furthermore, by simultaneously increasing the orientation of the PVA in advance, problems such as a decrease in orientation or dissolution of the PVA when immersed in water in the subsequent dyeing or stretching steps can be prevented, thereby achieving high optical properties. Furthermore, when the PVA-based resin layer is immersed in a liquid, the disordering of the polyvinyl alcohol molecules and the decrease in orientation can be suppressed compared to when the PVA-based resin layer does not contain a halide. This can improve the optical properties of a polarizer obtained through a treatment step in which the laminate is immersed in a liquid, such as a dyeing treatment and an underwater stretching treatment.Furthermore, by shrinking the laminate in the width direction through a drying shrinkage treatment, the optical properties can be improved.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 the resin substrate may be peeled off from the resin substrate / polarizer laminate, and any appropriate protective layer depending on the purpose may be laminated on the peeled surface. Details of such a method for producing a polarizer are described in, for example, JP-A-2012-73580 and Japanese Patent No. 6,470,455. The entire disclosures of these publications are incorporated herein by reference.

[0196] The polarizer is preferably composed of a laminate of two or more layers, and more preferably composed of a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate.

[0197] The thickness of the polarizer may be any appropriate thickness as long as the effects of the present invention are not impaired. In terms of further exhibiting the effects of the present invention, the thickness of the polarizer is preferably 1 μm to 15 μm, more preferably 2 μm to 12 μm, even more preferably 3 μm to 10 μm, and particularly preferably 3 μm to 8 μm.

[0198] The polarizer preferably exhibits absorptive dichroism at any wavelength between 380 nm and 780 nm. The single transmittance of the polarizer is, for example, 41.5% to 46.0%, preferably 43.0% to 46.0%, and more preferably 44.5% to 46.0%. The degree of polarization of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and even more preferably 99.9% or more.

[0199] <2-9-b. Protective Layer> The protective layer may be formed of any suitable film that can be used as a protective layer for a polarizer. Examples of materials that form the main component of the film include transparent resins such as cellulose-based resins such as triacetyl cellulose (TAC), polyester-based resins, polyvinyl alcohol-based resins, polycarbonate-based resins, polyamide-based resins, polyimide-based resins, polyethersulfone-based resins, polysulfone-based resins, polystyrene-based resins, polynorbornene-based resins, polyolefin-based resins, (meth)acrylic resins, and acetate-based resins. Examples of materials that form the main component of the film include thermosetting resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, and silicone-based resins, thermoplastic resins (particularly thermoplastic elastomers), and ultraviolet-curable resins. Other examples of materials that can be used as the main component of the film include glassy polymers such as siloxane-based polymers and the polymer films described in Japanese Patent Laid-Open No. 2001-343529 (WO 01 / 37007). Examples of materials that can be used as the main component of the film include resin compositions containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain, such as a resin composition containing an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile-styrene copolymer. The film can be, for example, an extrusion molded product of such a resin composition.

[0200] One embodiment of the protective layer contains a (meth)acrylic resin. Examples of the (meth)acrylic resin include a (meth)acrylic resin having a glutarimide structure. Examples of (meth)acrylic resins having a glutarimide structure are described in, for example, JP 2006-309033 A, JP 2006-317560 A, JP 2006-328329 A, JP 2006-328334 A, JP 2006-337491 A, JP 2006-337492 A, JP 2006-337493 A, JP 2006-337569 A, JP 2007-009182 A, JP 2009-161744 A, and JP 2010-284840 A. These descriptions are incorporated herein by reference.

[0201] The thickness of the protective layer may be any appropriate thickness as long as it does not impair the effects of the present invention. In order to further exhibit the effects of the present invention, the thickness of the protective layer is typically 300 μm or less, preferably 3 μm to 100 μm, more preferably 5 μm to 80 μm, and even more preferably 10 μm to 60 μm. In addition, when the protective layer has been subjected to a surface treatment, the thickness of the protective layer includes the thickness of the layer formed by the surface treatment (surface treatment layer).

[0202] <2-10. First Retardation Film> The first retardation film may be a retardation film having any appropriate optical and / or mechanical properties depending on the purpose. The first retardation film is located on the side opposite the viewing side of the polarizing film. The first retardation film is typically attached to the side opposite the viewing side of the polarizing film via any appropriate adhesive layer. The first retardation film may also serve as a protective layer on the side opposite the viewing side of the polarizer.

[0203] The thickness of the first retardation film is preferably 10 μm to 60 μm, and more preferably 30 μm to 50 μm.

[0204] The in-plane retardation Re(550) of the first retardation film is preferably 80 nm to 150 nm, more preferably 90 nm to 140 nm, and further preferably 100 nm to 130 nm.

[0205] The first retardation film preferably has refractive index characteristics that satisfy the relationship nx>ny>nz. The Nz coefficient of the first retardation film is preferably 1.1 to 3.0, and more preferably 1.3 to 2.7.

[0206] The first retardation film can preferably be arranged so that its slow axis is substantially parallel to the absorption axis of the polarizer. In this specification, the expressions "substantially parallel" and "almost parallel" include the case where the angle between the two directions is 0°±7°, preferably 0°±5°, and more preferably 0°±3°. The expressions "substantially orthogonal" and "almost orthogonal" include the case where the angle between the two directions is 90°±7°, preferably 90°±5°, and more preferably 90°±3°. Furthermore, in this specification, when simply referring to "orthogonal" or "parallel," it can include the substantially orthogonal or substantially parallel state.

[0207] The first retardation film preferably has an absolute value of the photoelastic coefficient of 2×10 -11 m 2 The absolute value of the photoelastic coefficient is more preferably 2.0×10 -13 m 2 / N ~ 1.5 x 10 -11 m 2 / N, and more preferably 1.0 × 10 -12 m 2 / N ~ 1.2 × 10 -11 m 2 / N. By appropriately adjusting the photoelastic coefficient of the first retardation film, an optical laminate suitable for suppressing display defects can be obtained even when a small object collides with or presses the screen over a small contact area. If the absolute value of the photoelastic coefficient is within this range, phase difference change is unlikely to occur when shrinkage stress occurs during heating. Therefore, by forming the first retardation film using a resin having such an absolute value of the photoelastic coefficient, thermal unevenness can be effectively prevented when the optical laminate is applied to an image display device.

[0208] The first retardation film may exhibit a reverse wavelength dispersion characteristic in which the retardation value increases with the wavelength of the measurement light, a positive wavelength dispersion characteristic in which the retardation value decreases with the wavelength of the measurement light, or a flat wavelength dispersion characteristic in which the retardation value changes little with the wavelength of the measurement light. The first retardation film preferably exhibits a flat wavelength dispersion characteristic. Specifically, the Re(450) / Re(550) of the first retardation film is preferably 0.99 to 1.03, and the Re(650) / Re(550) is preferably 0.98 to 1.02. By arranging a λ / 2 plate (first retardation film) and a λ / 4 plate (second retardation film) having flat wavelength dispersion characteristics at a predetermined axial angle, it is possible to obtain characteristics close to ideal reverse wavelength dispersion characteristics, and as a result, it is possible to realize excellent antireflection properties.

[0209] The first retardation film may be composed of any appropriate resin film that can satisfy the above-mentioned characteristics. Representative examples of such resins include cyclic olefin-based resins, polycarbonate-based resins, cellulose-based resins, polyester-based resins, polyvinyl alcohol-based resins, polyamide-based resins, polyimide-based resins, polyether-based resins, polystyrene-based resins, and acrylic-based resins. Among these, cyclic olefin-based resins may be preferably used. The first retardation film may be obtained, for example, by stretching a film formed from the above-mentioned resin. Details of the cyclic olefin-based resin and the stretching method of the resin film (method of forming the retardation film) are described, for example, in JP 2015-210459 A and JP 2016-105166 A. The disclosures in these publications are incorporated herein by reference.

[0210] <<2-11. Second Retardation Film>> The second retardation film may be a retardation film having any suitable optical and / or mechanical properties depending on the purpose. The second retardation film is located on the side opposite the viewing side of the first retardation film. The second retardation film is typically attached to the side opposite the viewing side of the first retardation film via any suitable adhesive layer.

[0211] The thickness of the second retardation film is preferably 10 μm to 50 μm, and more preferably 20 μm to 40 μm.

[0212] The in-plane retardation Re(550) of the second retardation film is preferably 10 nm to 60 nm, more preferably 20 nm to 50 nm, and even more preferably 30 nm to 40 nm.

[0213] The second retardation film preferably has refractive index characteristics that satisfy the relationship nz>nx>ny. The Nz coefficient of the second retardation film is preferably −10 to −0.1, and more preferably −5 to −1.

[0214] The second retardation film can be preferably disposed so that its slow axis is substantially perpendicular to the absorption axis of the polarizer.

[0215] The second retardation film may be composed of any appropriate resin film that can satisfy the above-mentioned characteristics. Such a resin may typically be a polymer having negative intrinsic birefringence. A polymer having negative intrinsic birefringence refers to a polymer in which, when oriented by stretching or the like, the refractive index in the orientation direction becomes relatively small. Examples of polymers having negative intrinsic birefringence include those in which chemical bonds or functional groups with large polarization anisotropy, such as aromatic or carbonyl groups, are introduced into the side chains of the polymer. Specific examples include modified polyolefin-based resins (e.g., modified polyethylene-based resins), acrylic-based resins, styrene-based resins, maleimide-based resins, fumaric acid ester-based resins, etc. The second retardation film may be obtained, for example, by appropriately stretching a film formed from the above-mentioned resin.

[0216] In one embodiment of the present invention, the optical stack includes a first retardation film and a second retardation film, but the optical stack does not necessarily include the first retardation film and / or the second retardation film.

[0217] <<3. Image display device>> The optical laminate according to an embodiment of the present invention can be applied to an image display device. Accordingly, one embodiment of the present invention also encompasses an image display device using such an optical laminate. Representative examples of image display devices include liquid crystal display devices and organic EL display devices. The image display device according to an embodiment of the present invention is preferably an organic EL display device. In other words, the pressure-sensitive adhesive sheet or optical laminate according to an embodiment of the present invention is preferably a component used in an organic EL display device.

[0218] An image display device according to an embodiment of the present invention typically includes an optical laminate according to an embodiment of the present invention on its viewing side. The image display device includes an image display panel. The image display panel includes an image display cell. Note that the image display device may be referred to as an optical display device, the image display panel may be referred to as an optical display panel, and the image display cell may be referred to as an optical display cell.

[0219] The present invention will be specifically described below using examples, but the present invention is not limited to these examples. The test and evaluation methods used in the examples are as follows. The term "parts" means "parts by weight" unless otherwise specified, and the term "%" means "% by weight" unless otherwise specified.

[0220] <Production of Photocurable Composition (I-1)> 83.3 parts by weight of n-butyl acrylate (BA), 4.2 parts by weight of acrylic acid (AA), 12.5 parts by weight of N-acryloylmorpholine (ACMO), and 0.2 parts by weight of 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropan-1-one (trade name "Omnirad 127D", manufactured by IGM Resins B.V.) as a photopolymerization initiator were placed in a four-neck flask and irradiated with ultraviolet light under a nitrogen atmosphere to obtain a partially photopolymerized monomer syrup. The ultraviolet light irradiation was continued until the viscosity of the liquid in the flask reached approximately 20 Pa s. The viscosity was measured using a BH viscometer No. The measurement was carried out using a No. 5 rotor at 10 rpm and a measurement temperature of 30°C.

[0221] The resulting monomer syrup was mixed with 0.05 parts by weight of 1,9-nonanediol diacrylate (NDDA) as a crosslinking agent to obtain a photocurable composition (I-1).

[0222] <Preparation of Photocurable Composition (I-2)> Photocurable composition (I-2) was prepared in the same manner as for photocurable composition (I-1), except that the types and contents of the monomer and crosslinking agent were changed as shown in Table 1.

[0223]

[0224] The abbreviations in Table 1 are as follows: BA: n-butyl acrylate AA: acrylic acid ACMO: acryloylmorpholine NDDA: 1,9-nonanediol diacrylate Omnirad127D: 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropan-1-one (trade name "Omnirad127D", manufactured by IGM Resins B.V.)

[0225] <Production of Photocurable Composition (II)> A photocurable composition (II) was produced by mixing 100 parts by weight of 1,9-nonanediol diacrylate (NDDA) as a crosslinking agent (photopolymerizable compound), 3.0 parts by weight of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (trade name "Omnirad 819", manufactured by IGM Resins B.V.) as a photopolymerization initiator, and 103 parts by weight of ethyl acetate as a solvent.

[0226] Example 1 First, a photocurable composition (I-1) was applied with an applicator to the release-treated surface of a first release liner (trade name "Diafoil MRF", thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) having a release-treated surface on one side, to form a coating layer. Next, the release-treated surface of a second release liner (trade name "Diafoil MRE", thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) having a release-treated surface on one side was bonded to the coating layer formed on the first release liner (see FIG. 3A). Next, an LED (peak wavelength 340 nm, illuminance 9 mW / cm) was irradiated onto the coating layer between the release liners from the first release liner side. 2, cumulative light intensity 2700 mJ / cm 2 ) was irradiated with light. As a result, the coating layer was photocured, and a laminate composed of the first release liner / cured product layer (thickness: 80 μm) / second release liner was formed.

[0227] Next, the second release liner was peeled off from the obtained laminate (see FIG. 3B ), and the photocurable composition (II) was applied to the exposed surface of the cured material layer. The amount of photocurable composition (II) applied was determined so that the total solids content excluding the solvent in the photocurable composition (II) was 20 parts by weight relative to 80 parts by weight of the photocurable composition (I-1) used to form the cured material layer, resulting in a coating thickness of approximately 40 μm. Next, a drying treatment was performed in a dryer at 110°C for 3 minutes. The coating and drying treatments allowed the photocurable composition (II) to penetrate into the cured material layer, and also evaporated the solvent. This resulted in a precursor layer of a pressure-sensitive adhesive sheet.

[0228] Next, the release-treated surface of a third release liner (trade name "Diafoil MRE", thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) having a release-treated surface on one side was bonded to the precursor layer on the first release liner. Next, a black light (manufactured by Toshiba, wavelength 320 nm to 400 nm, illuminance 2.5 mW / cm) was irradiated onto the precursor layer between the release liners from the first release liner side. 2 , cumulative light intensity 2400 mJ / cm 2 ) was irradiated with light (see FIG. 3C). As a result, the precursor layer was photocured, and the PSA sheet (thickness: 100 μm) of Example 1 was formed (see FIG. 1). In detail, a laminate composed of the first release liner / the PSA sheet (thickness: 100 μm) / the third release liner was formed.

[0229] (Example 2) A pressure-sensitive adhesive sheet (thickness 64 μm) of Example 2 was obtained in the same manner as in Example 1, except that the thickness of the cured product layer was changed to 51 μm and the coating thickness of the photocurable composition (II) was changed to approximately 26 μm (see FIG. 1).

[0230] (Example 3) First, a pressure-sensitive adhesive sheet (a first pressure-sensitive adhesive portion having a thickness of 40 μm) was obtained in the same manner as in Example 1, except that the thickness of the cured product layer was changed to 32 μm and the photocurable composition (II) was applied to a coating thickness of approximately 16 μm.

[0231] Next, a pressure-sensitive adhesive sheet (a second adhesive portion having a thickness of 12 μm) was obtained in the same manner as in Example 1, except that photocurable composition (I-2) was used instead of photocurable composition (I-1), the thickness of the cured product layer was changed to 12 μm, and photocurable composition (II) was not applied to the cured product layer.

[0232] Next, an acrylic resin film having a glutarimide structure (manufactured by Kaneka Corporation, product name "HTX", thickness 40 μm) was prepared as substrate A. A first adhesive portion was bonded to one surface of substrate A, and a second adhesive portion was bonded to the other surface of substrate A, thereby obtaining a pressure-sensitive adhesive sheet of Example 3 configured as the first adhesive portion (thickness 40 μm) / substrate A (thickness 40 μm) / second adhesive portion (thickness 12 μm) (see FIG. 4A ).

[0233] (Example 4) First, a pressure-sensitive adhesive sheet (a first pressure-sensitive adhesive portion having a thickness of 20 μm) was obtained in the same manner as in Example 1, except that the thickness of the cured product layer was changed to 16 μm and the photocurable composition (II) was applied to a coating thickness of approximately 8 μm.

[0234] Next, a pressure-sensitive adhesive sheet (a second adhesive portion having a thickness of 140 μm) was obtained in the same manner as in Example 1, except that the thickness of the cured product layer was changed to 112 μm and the photocurable composition (II) was applied to a coating thickness of approximately 56 μm.

[0235] Finally, the first adhesive portion was bonded to one surface of the substrate A, and the second adhesive portion was bonded to the other surface of the substrate A, thereby obtaining an adhesive sheet of Example 4 composed of the first adhesive portion (thickness 20 μm) / substrate A (thickness 40 μm) / second adhesive portion (thickness 140 μm) (see FIG. 4A ).

[0236] (Example 5) In producing the second adhesive portion, the thickness of the cured product layer was changed to 192 μm, and the photocurable composition (II) was applied to a coating thickness of approximately 96 μm. The same method as in Example 4 was used to obtain an adhesive sheet of Example 5 composed of a first adhesive portion (thickness 20 μm) / substrate A (thickness 40 μm) / second adhesive portion (thickness 240 μm) (see FIG. 4A ).

[0237] Example 6 An adhesive sheet of Example 6 composed of a first adhesive portion (thickness 20 μm) / substrate A (thickness 80 μm) / second adhesive portion (thickness 200 μm) was obtained by the same method as in Example 4, except that a TAC film (manufactured by Fujifilm Corporation, product name "Fujitac", thickness 80 μm) was used as substrate A instead of an acrylic resin film, and that the thickness of the cured product layer was changed to 160 μm in producing the second adhesive portion, and that photocurable composition (II) was applied to a coating thickness of approximately 80 μm (see FIG. 4A ).

[0238] (Example 7) First, a pressure-sensitive adhesive sheet (first pressure-sensitive adhesive portion having a thickness of 20 μm) was obtained by the same method as in Example 1, except that the thickness of the cured product layer was changed to 16 μm and the photocurable composition (II) was applied to a coating thickness of approximately 8 μm.

[0239] Next, an acrylic resin film having a glutarimide structure (manufactured by Kaneka Corporation, product name "HTX", thickness 40 μm) was prepared as substrate A. As substrate B, the same acrylic resin film as substrate A was prepared.

[0240] Next, a pressure-sensitive adhesive sheet (a second pressure-sensitive adhesive portion having a thickness of 100 μm) was obtained by the same method as in Example 1, except that the thickness of the cured product layer was changed to 80 μm and the photocurable composition (II) was applied to a coating thickness of approximately 40 μm. A third pressure-sensitive adhesive portion was obtained by the same method.

[0241] Finally, the first adhesive portion, substrate A, second adhesive portion, substrate B, and third adhesive portion were bonded together in this order to obtain an adhesive sheet of Example 7 configured as first adhesive portion (thickness 20 μm) / substrate A (thickness 40 μm) / second adhesive portion (thickness 100 μm) / substrate B (thickness 40 μm) / third adhesive portion (thickness 100 μm) (see FIG. 4B ).

[0242] Comparative Example 1 A pressure-sensitive adhesive sheet (thickness 100 μm) of Comparative Example 1 was obtained in the same manner as in Example 1, except that photocurable composition (I-2) was used instead of photocurable composition (I-1), the thickness of the cured product layer was changed to 100 μm, and photocurable composition (II) was not applied to the cured product layer (see FIG. 1 ).

[0243] Comparative Example 2 A pressure-sensitive adhesive sheet (thickness 70 μm) of Comparative Example 2 was obtained in the same manner as in Comparative Example 1, except that the thickness of the cured product layer was changed to 70 μm (see FIG. 1).

[0244] (Comparative Example 3) First, except that the thickness of the cured product layer was changed to 40 μm, a pressure-sensitive adhesive sheet (first adhesive portion having a thickness of 40 μm) was obtained by the same method as in Comparative Example 1. Except that this first adhesive portion was used, a pressure-sensitive adhesive sheet of Comparative Example 3 configured as first adhesive portion (thickness 40 μm) / substrate A (thickness 40 μm) / second adhesive portion (thickness 12 μm) was obtained by the same method as in Example 3 (see FIG. 4A ).

[0245] Table 2 shows the configurations of the pressure-sensitive adhesive sheets of the examples and comparative examples.

[0246]

[0247] <Test 1> Test 1 was performed on the prepared pressure-sensitive adhesive sheet using the method described above, and the coloring ratio X1 was determined. In Test 1, a glass plate with a thickness of 1.2 mm was used. The piercing test T1 was performed at room temperature (23°C ± 3°C) using an Instron product named "5581." The optical microscope used was a VHX-8000 manufactured by Keyence Corporation. In Examples 3 to 6 and Comparative Example 3, the pressure-sensitive adhesive sheet was positioned so that the first adhesive portion was located closer to the piercing jig than the second adhesive portion. In Example 7, the pressure-sensitive adhesive sheet was positioned so that the first adhesive portion was located closer to the piercing jig than the third adhesive portion.

[0248] <Test 2> Test 2 was performed on the prepared pressure-sensitive adhesive sheet using the method described above, and the coloring ratio X2 was determined. In Test 2, a 1.2 mm thick glass plate was used. An AR film (AR + HC thickness: 4 μm, substrate thickness: 80 μm, total thickness: 85 μm) manufactured by Dexerials Corporation was used as the antireflection laminate. The antireflection laminate was positioned so that the substrate contained in the antireflection laminate was in contact with the surface of the pressure-sensitive adhesive sheet. Puncture test T2 was performed using an Instron product named "5581" at room temperature (23°C ± 3°C). A VHX-8000 manufactured by Keyence Corporation was used as the optical microscope. In Examples 3 to 6 and Comparative Example 3, the pressure-sensitive adhesive sheet was positioned so that the first adhesive portion was located closer to the piercing jig than the second adhesive portion. In Example 7, the pressure-sensitive adhesive sheet was positioned so that the first adhesive portion was located closer to the piercing jig than the third adhesive portion.

[0249] <Test 3> Test 3 was performed on the prepared pressure-sensitive adhesive sheet using the method described above, and the coloring ratio X3 was determined. In Test 3, a glass plate with a thickness of 1.2 mm was used. As the antireflection laminate, an AR film (AR + HC thickness: 4 μm, substrate thickness: 80 μm, total thickness: 85 μm) manufactured by Dexerials Corporation was used. The antireflection laminate was positioned so that the substrate contained in the antireflection laminate was in contact with the surface of the pressure-sensitive adhesive sheet. As the polarizing film with retardation film, one prepared by the manufacturing method described below was used. As the polarizing film with retardation film, a polarizing film contained in the polarizing film with retardation film was positioned so that the polarizing film in contact with the surface of the pressure-sensitive adhesive sheet. The piercing test T3 was performed under room temperature (23°C ± 3°C) using an Instron product name "5581". As the optical microscope, a VHX-8000 manufactured by Keyence Corporation was used. In Examples 3 to 6 and Comparative Example 3, the pressure-sensitive adhesive sheet was arranged so that the first adhesive portion was located closer to the piercing jig than the second adhesive portion. In Example 7, the pressure-sensitive adhesive sheet was arranged so that the first adhesive portion was located closer to the piercing jig than the third adhesive portion.

[0250] [Method for Producing Polarizing Film with Retardation Film] (Producing Polarizing Film) A long, amorphous isophthalic copolymerized 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. A PVA-based resin (100 parts by weight) containing 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 "GOHSEFIRM") in a 9:1 ratio was prepared. 13 parts by weight of potassium iodide was added to 100 parts by weight of the resulting PVA-based resin, and the resulting solution was dissolved in water to prepare an aqueous PVA solution (coating solution). The PVA-based resin layer was coated on the corona-treated surface of the resin substrate and dried at 60°C to form a 13 μm-thick PVA-based resin layer, producing a laminate.

[0251] The obtained laminate was uniaxially stretched 2.4 times in the longitudinal direction (machine direction) in an oven at 130°C (auxiliary in-air stretching treatment). Next, the laminate was immersed for 30 seconds in an insolubilizing bath (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40°C (insolubilizing treatment). Next, the laminate was immersed for 60 seconds in a dyeing bath (an iodine aqueous solution obtained by blending iodine and potassium iodide in a weight ratio of 1:7 with 100 parts by weight of water) at a liquid temperature of 30°C while adjusting the concentration so that the single transmittance (Ts) of the finally obtained polarizer would be a desired value (dyeing treatment).

[0252] Next, the laminate was immersed for 30 seconds in a crosslinking bath (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 40° C. (crosslinking treatment). Thereafter, while being 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., the laminate was uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls operating at different peripheral speeds so that the total stretch ratio was 5.5 times (underwater stretching treatment).

[0253] Thereafter, the laminate was immersed in a cleaning bath (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 20°C (cleaning treatment), and then brought into contact with a SUS heated roll whose surface temperature was maintained at about 75°C while being dried in an oven maintained at about 90°C (drying shrinkage treatment).

[0254] In this way, a polarizer with a thickness of approximately 5 μm was formed on the resin substrate. An HC-TAC film (first protective film) was bonded to the surface of the obtained polarizer (the surface opposite to the resin substrate) via a UV-curable adhesive. Specifically, the curable adhesive was applied to a thickness of 1.0 μm, and the films were bonded using a rolling mill. The adhesive was then cured by irradiation with UV light from the protective film side. The HC-TAC film was a film in which a hard coat (HC) layer (7 μm thick) was formed on a triacetyl cellulose (TAC) film (25 μm thick), and the TAC film was bonded to the polarizer side.

[0255] 97.0 parts by weight of methyl methacrylate (MMA, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name "Methyl Methacrylate Monomer"), 3.0 parts by weight of a copolymerizable monomer represented by the following formula (1e), and 0.2 parts by weight of a polymerization initiator (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name "2,2'-azobis(isobutyronitrile)") were dissolved in 200 parts by weight of toluene. Next, a polymerization reaction was carried out for 5.5 hours while heating to 70°C under a nitrogen atmosphere, yielding a boron-containing acrylic resin solution (solids concentration: 33%). The resulting boron-containing acrylic polymer had a Tg of 110°C and an Mw of 80,000. 20 parts by weight of the resulting boron-containing acrylic resin was dissolved in 80 parts by weight of methyl ethyl ketone to obtain a resin solution (20%).

[0256] The resin substrate was peeled from the polarizer, and a resin solution was applied to the peeled surface using a wire bar. The resulting coating was then dried at 60° C. for 5 minutes to form a second protective film (thickness: 400 nm) composed of a solidified coating of the organic solvent solution of the resin. This resulted in a polarized film having a configuration of [TAC film with HC layer (first protective film) / polarizer / solidified layer of boron-containing acrylic resin (second protective film)].

[0257] (Preparation of First Retardation Film) In a batch polymerization apparatus consisting of two vertical reactors equipped with stirring blades and reflux condensers controlled at 100°C, 29.60 parts by weight (0.046 mol) of bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane, 29.21 parts by weight (0.200 mol) of isosorbide (ISB), 42.28 parts by weight (0.139 mol) of spiroglycol (SPG), 63.77 parts by weight (0.298 mol) of diphenyl carbonate (DPC), and 1.19 × 10 mol of calcium acetate monohydrate as a catalyst were added. -2 Part by weight (6.78 x 10 -5 mol) was charged. After purging the reactor with nitrogen under reduced pressure, heating was performed with a heat medium, and stirring was initiated when the internal temperature reached 100°C. 40 minutes after the start of the temperature increase, the internal temperature reached 220°C, and while controlling to maintain this temperature, pressure reduction was initiated. 90 minutes after reaching 220°C, the pressure was reduced to 13.3 kPa. Phenol vapor by-produced during the polymerization reaction was introduced into a reflux condenser at 100°C, and a small amount of monomer components contained in the phenol vapor were returned to the reactor, while uncondensed phenol vapor was introduced into a condenser at 45°C and recovered. Nitrogen was introduced into the first reactor, and the pressure was temporarily restored to atmospheric pressure. The oligomerized reaction liquid in the first reactor was then transferred to the second reactor. Next, heating and pressure reduction in the second reactor were initiated, and the internal temperature reached 240°C and the pressure reached 0.2 kPa in 50 minutes. Polymerization was then allowed to proceed until the predetermined stirring power was achieved. When the predetermined power was reached, nitrogen was introduced into the reactor to restore the pressure, and 100 parts by weight of the produced polyester carbonate resin was melt-kneaded with 0.7 parts by mass of PMMA, and the mixture was extruded into water, and the strands were cut to obtain pellets.

[0258] The obtained polyester carbonate resin (pellets) was vacuum dried at 80 ° C. for 5 hours, and then a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder set temperature: 250 ° C.), a T-die (width 200 mm, set temperature: 250 ° C.), a chill roll (set temperature: 120-130 ° C.) and a film-forming device equipped with a winder were used to produce a long resin film having a thickness of 105 μm. The obtained long resin film was stretched 2.8 times in the width direction at 138 ° C. while adjusting to obtain a predetermined retardation, to obtain a first retardation film having a thickness of 37 μm. The Re (550) of the obtained first retardation film was 144 nm, and Re (450) / Re (550) was 0.86.

[0259] (Preparation of second retardation film) 20 parts by weight of a side-chain liquid crystal polymer represented by the following chemical formula (I) (the numbers 65 and 35 in the formula indicate the mol% of the monomer unit, and are conveniently represented as a block polymer: weight average molecular weight 5000), 80 parts by weight of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF: trade name Paliocolor LC242) and 5 parts by weight of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals: trade name Irgacure 907) were dissolved in 200 parts by weight of cyclopentanone to prepare a liquid crystal coating solution. Then, the coating solution was applied to a PET substrate that had been subjected to vertical alignment treatment using a bar coater, and the liquid crystal was aligned by heating and drying at 80 ° C. for 4 minutes. This liquid crystal layer was irradiated with ultraviolet light, and the liquid crystal layer was cured, thereby forming a liquid crystal alignment solidified layer (second retardation film, thickness 3 μm) exhibiting a refractive index characteristic of nz > nx = ny on the substrate.

[0260] (Preparation of adhesive) 5 parts by weight of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-303"), 35 parts by weight of 4-hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.), 24 parts by weight of neopentyl glycol diacrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Light Acrylate NP-A"), 10 parts by weight of isocyanuric acid EO-modified triacrylate (manufactured by Toagosei Co., Ltd., trade name "Aronix M-315"), 5 parts by weight of pentaerythritol triacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name "A-TMM-3LM-N"), 15 parts by weight of polyurethane-based acrylic oligomer (manufactured by Mitsubishi Chemical Corporation, trade name "UV3000B"), 3 parts by weight of photopolymerization initiator (manufactured by IGM Resins, trade name "Omnirad" 184"), 2 parts by weight of a photopolymerization initiator (manufactured by San-Apro Co., Ltd., trade name "CPI-100P"), and 1 part by weight of boric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were mixed and stirred for 3 hours to obtain an active energy ray-curable adhesive.

[0261] (Preparation of Pressure-Sensitive Adhesive Sheet D1) 91 parts by weight of n-butyl acrylate (BA), 2.7 parts by weight of acrylic acid (AA), 0.3 parts by weight of 4-hydroxybutyl acrylate (4HBA), 6 parts by weight of acryloylmorpholine (ACMO), and 0.2 parts by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator were charged into a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser. Nitrogen gas was introduced while gently stirring to replace the atmosphere in the flask with nitrogen, and the liquid temperature in the flask was maintained at around 55°C, and the polymerization reaction was allowed to proceed for 7 hours. Next, ethyl acetate was added to the resulting reaction liquid to adjust the solids concentration to 12% by weight, thereby obtaining a (meth)acrylic polymer solution.

[0262] A pressure-sensitive adhesive was obtained by mixing 0.15 parts by weight of trimethylolpropane / tolylene diisocyanate trimer adduct (Coronate L, manufactured by Tosoh Corporation), 0.25 parts by weight of benzoyl peroxide (Niper BMT, manufactured by NOF Corporation) and 0.075 parts by weight of 3-glycidoxypropyltrimethoxysilane (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) with a solution of the (meth)acrylic polymer so that the contents per 100 parts by weight of the solid content of the (meth)acrylic polymer were the same.

[0263] The above adhesive was applied to the release surface of a 38 μm thick PET film (Mitsubishi Chemical Polyester Film Corporation, MRF38), a release liner with a silicone treatment on the release surface, and then dried in an air-circulating constant temperature oven set to a predetermined temperature to form adhesive sheet D1 (thickness 5 μm).

[0264] (Preparation of Pressure-Sensitive Adhesive Sheet D2) A four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser was charged with 80.3 parts by weight of n-butyl acrylate (BA), 16 parts by weight of 2-phenoxyethyl acrylate (PEA), 0.2 parts by weight of acrylic acid (AA), 0.5 parts by weight of 4-hydroxybutyl acrylate (HBA), 3 parts by weight of N-vinylpyrrolidone (NVP), and 0.2 parts by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator. Nitrogen gas was introduced into the flask with gentle stirring to replace the atmosphere with nitrogen, and the liquid temperature in the flask was maintained at around 55°C, allowing the polymerization reaction to proceed for 7 hours. Next, ethyl acetate was added to the resulting reaction liquid to adjust the solids concentration to 12% by weight, thereby obtaining a (meth)acrylic polymer solution.

[0265] These were mixed into a solution of the (meth)acrylic polymer so that the contents per 100 parts by weight of the solid content of the (meth)acrylic polymer were 0.17 parts by weight of trimethylolpropane hexamethylene diisocyanate (Takenate D160N, manufactured by Mitsui Chemicals, Inc.), 0.25 parts by weight of benzoyl peroxide (Niper BMT, manufactured by NOF Corporation), 0.2 parts by weight of an acetoacetyl group-containing silane coupling agent (A100, manufactured by Soken Chemical & Engineering Co., Ltd.), 0.2 parts by weight of an epoxy group-containing oligomer type silane coupling agent (X-41-1056, manufactured by Shin-Etsu Chemical Co., Ltd.), and 0.3 parts by weight of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), to obtain a pressure-sensitive adhesive.

[0266] The above adhesive was applied to the release surface of a 38 μm thick PET film (Mitsubishi Chemical Polyester Film Corporation, MRF38), a release liner with a silicone treatment on the release surface, and then dried in an air-circulating constant temperature oven set to a predetermined temperature to form adhesive sheet D2 (thickness 20 μm).

[0267] (Preparation of Polarizing Film with Retardation Film) A pressure-sensitive adhesive sheet D1 (thickness: 5 μm) was transferred from a release liner to the surface of the second protective film of the polarizing film, and a first retardation film was attached to the polarizing film via the pressure-sensitive adhesive sheet D1 to obtain a laminate. At this time, the slow axis of the first retardation film was arranged at an angle of 45° with respect to the absorption axis of the polarizer.

[0268] An active energy ray curable adhesive was applied to one side of the second retardation film using an MCD coater (manufactured by Fuji Machine Co., Ltd.) so that the thickness after curing would be 1 μm, and the laminate was then attached to the surface of the first retardation film using a roller. Thereafter, the adhesive was cured by irradiating it with ultraviolet light from the second retardation film side using an active energy ray irradiation device, and then dried with hot air at 70° C. for 3 minutes.

[0269] Onto the surface of the second retardation film of the laminate obtained as described above, an adhesive sheet D2 (thickness 20 μm) was transferred from the release liner to obtain a polarizing film (thickness 104 μm) with a retardation film having a configuration of polarizing film (thickness 38 μm) / adhesive sheet D1 (thickness 5 μm) / first retardation film (thickness 37 μm) / adhesive layer (thickness 1 μm) / second retardation film (thickness 3 μm) / adhesive sheet D2 (thickness 20 μm).

[0270] <Pressure Test> The pressure-sensitive adhesive sheets obtained in the Examples and Comparative Examples were cut into 5 cm x 5 cm pieces to serve as test samples, which were then bonded to a 1.2 mm thick glass plate. The test samples bonded to the glass plate were placed on the stage of a measuring device (Instron, product name "5581") equipped with a piercing jig. In Examples 3 to 6 and Comparative Example 3, the pressure-sensitive adhesive sheet was positioned so that the first adhesive portion was located closer to the piercing jig than the second adhesive portion. In Example 7, the pressure-sensitive adhesive sheet was positioned so that the first adhesive portion was located closer to the piercing jig than the third adhesive portion. The radius of curvature R of the tip of the piercing jig was 9 mm. At room temperature (23°C ± 3°C), the piercing jig was pierced into the test sample on the stage at a piercing speed of 0.9 mm / min, and the displacement L (μm) was measured after reaching 8 kgf and maintaining the pressure for 20 seconds. Based on the displacement L (μm) and the total thickness T (μm) of the pressure-sensitive adhesive sheet, the distortion ΔL of the pressure-sensitive adhesive sheet was calculated using the following formula: ΔL=(L / T)×100

[0271] The results of Tests 1 to 3 and the compression test are shown in Table 3.

[0272]

[0273] As can be seen from Table 3, the pressure-sensitive adhesive sheets of the examples met at least one selected from the group consisting of the above-mentioned requirements (i) to (iii). The pressure-sensitive adhesive sheets of the examples exhibited small amounts of distortion in the compression test. From these results, it can be assumed that the pressure-sensitive adhesive sheets of the examples are suitable for dispersing stress when a localized load is applied. In other words, it can be said that the pressure-sensitive adhesive sheets of the examples are suitable for suppressing damage to image display panels due to localized loads.

[0274] The pressure-sensitive adhesive sheet according to the embodiment of the present invention can be suitably used in image display devices (typically, liquid crystal display devices and organic EL display devices).

Claims

1. A pressure-sensitive adhesive sheet that satisfies at least one selected from the group consisting of the following requirements (i) to (iii): (i) The coloring ratio X1 specified by Test 1 below satisfies X1≦1.1%. (ii) The coloring ratio X2 specified by Test 2 below satisfies X2≦1.8%. (iii) The coloring ratio X3 specified by Test 3 below satisfies X3≦4.6%. Test 1: A laminate S1 is prepared in which a glass plate, a press scale (manufactured by Fujifilm Corporation, for medium pressure (MS)), and the pressure-sensitive adhesive sheet are laminated in this order. A piercing test T1 is performed in which a piercing jig with a tip curvature radius R of 550 μm is used to pierce the laminate S1 from the pressure-sensitive adhesive sheet side at a piercing speed of 0.9 mm / min until a load of 0.2 kgf is reached. After the piercing test T1, the surface of the prescale is observed using an optical microscope under the conditions of a magnification of 300 times and a field of view of 840 μm × 1120 μm. 2 ) to the area A1 (μm 2 ) is specified as the coloring ratio X1 (%). Test 2: A laminate S2 is prepared by laminating a glass plate, a prescale (manufactured by Fujifilm Corporation, for medium pressure (MS)), the pressure-sensitive adhesive sheet, and an antireflection laminate having a thickness of 85 μm in this order. A piercing test T2 is performed in which a piercing jig with a tip curvature radius R of 550 μm is used to pierce the laminate S2 from the antireflection laminate side at a piercing speed of 0.9 mm / min until a load of 0.5 kgf is reached. After the piercing test T2, the surface of the prescale is observed using an optical microscope at a magnification of 300 times and a field of view of 840 μm x 1120 μm. The area A (μm 2 ) to the area A2 (μm 2 ) is specified as the coloring ratio X2 (%). Test 3: A laminate S3 is prepared by laminating a glass plate, a prescale (manufactured by Fujifilm Corporation, for medium pressure (MS)), a polarizing film with a 104 μm thick retardation film, the pressure-sensitive adhesive sheet, and an antireflection laminate with a thickness of 85 μm in this order. A piercing test T3 is performed in which a piercing jig with a tip curvature radius R of 550 μm is used to pierce the laminate S3 from the antireflection laminate side at a piercing speed of 0.9 mm / min until the load reaches 1.0 kgf. After the piercing test T3, the surface of the prescale is observed using an optical microscope at a magnification of 300 times and a field of view of 840 μm x 1120 μm. The area A (μm 2 ) to the area A3 (μm 2 ) is specified as the coloring ratio X3 (%).

2. The pressure-sensitive adhesive sheet according to claim 1, comprising: a polymer P1 formed from a photocurable composition (I); and a polymer P2 formed from a photocurable composition (II) different from the photocurable composition (I).

3. The pressure-sensitive adhesive sheet according to claim 2, wherein the photocurable composition (I) contains a monomer component.

4. The pressure-sensitive adhesive sheet according to claim 3, wherein the monomer component comprises at least one selected from the group consisting of an acidic group-containing monomer and a nitrogen atom-containing monomer.

5. The pressure-sensitive adhesive sheet according to claim 3, wherein the photocurable composition (I) further contains a crosslinking agent.

6. The pressure-sensitive adhesive sheet according to claim 2, wherein the photocurable composition (II) contains a polyfunctional (meth)acrylate.

7. The pressure-sensitive adhesive sheet according to claim 2, wherein the photocurable composition (I) and the photocurable composition (II) do not contain an ultraviolet absorber.

8. The pressure-sensitive adhesive sheet according to claim 2, obtained by adding the photocurable composition (II) to a cured layer formed from the photocurable composition (I) and curing the resulting layer.

9. A method for producing a pressure-sensitive adhesive sheet according to any one of claims 2 to 8, comprising the steps of adding the photocurable composition (II) to a cured layer formed from the photocurable composition (I) and curing the composition.

10. An optical laminate comprising the pressure-sensitive adhesive sheet according to any one of claims 1 to 8 and an optical member.

11. An image display device comprising the optical laminate according to claim 10.

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