Adhesive composition, adhesive sheet, optical film with adhesive sheet, method for producing adhesive sheet and optical film with adhesive sheet

Abstract

To provide an adhesive composition capable of producing an adhesive sheet with a low environmental load by reducing a waste amount of a release liner required for the production of an adhesive sheet.SOLUTION: There is provided an adhesive composition which is a photocurable adhesive composition comprising a monomer group including a (meth)acrylic monomer and / or a partial polymerization product of the monomer group and a photopolymerization initiator. The adhesive composition further comprises an antioxidant. The adhesive composition has a peeling force PS1 of 1.0 N / 50 mm or less as determined by a test. The adhesive sheet is formed from the adhesive composition.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet, an optical film with a pressure-sensitive adhesive sheet, and a method for producing the pressure-sensitive adhesive sheet and the optical film with a pressure-sensitive adhesive sheet. [Background technology]

[0002] Various image display devices, such as liquid crystal display devices and electroluminescence (EL) display devices, generally include an optical laminate including an optical film such as a polarizing film and an adhesive sheet. An adhesive sheet is usually used for bonding between the optical films included in the optical laminate and for bonding between the optical laminate and an image display panel. A typical adhesive sheet is a sheet obtained by polymerizing and crosslinking a monomer group including an acrylic monomer, a silicone monomer, and the like to harden the monomer group.

[0003] Patent Document 1 discloses an example of a pressure-sensitive adhesive sheet, which is produced by irradiating a coating layer of a pressure-sensitive adhesive composition disposed between two release liners with light. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6688054 Summary of the Invention [Problem to be solved by the invention]

[0005] Formation of an adhesive sheet by curing usually requires energy such as heat or light. According to a method that utilizes light (photocuring method), the amount of energy required to form an adhesive sheet can be reduced compared to, for example, a method (thermal curing method) in which a coating layer containing an adhesive composition and a solvent is thermally cured in an oven. However, from the viewpoint of reducing the environmental load during the production of an adhesive sheet, it is not sufficient to only focus on the amount of energy required to cure the coating layer.

[0006] Therefore, an object of the present invention is to provide a pressure-sensitive adhesive composition that enables the production of pressure-sensitive adhesive sheets with low environmental impact by reducing the amount of release liners that are discarded in the production of pressure-sensitive adhesive sheets. [Means for solving the problem]

[0007] The present invention relates to A photocurable pressure-sensitive adhesive composition comprising a monomer group including a (meth)acrylic monomer and / or a partial polymer of the monomer group, and a photopolymerization initiator, The pressure-sensitive adhesive composition further comprises an antioxidant, The adhesive composition has a peel strength PS1 of 1.0 N / 50 mm or less, as determined by the following test. provide. Test: A laminate including, in this order, a base sheet, a coating layer including the pressure-sensitive adhesive composition, and a release liner having a release layer with a thickness of 120 nm was subjected to an illuminance of 2.42 mW / cm 2 , irradiation time 10 The present invention performs two steps: step A, in which an adhesive sheet is formed from the coating layer by irradiating the coating layer with ultraviolet light under conditions of 1000 nm to 2000 nm, and step B, in which the release liner is peeled off from the adhesive sheet. Steps A and B are repeatedly performed using the release liner peeled off in step B to reuse the release liner. The peel force PS1 between the reused release liner obtained in step B, which has been peeled off once from the adhesive sheet counting from an unused state, and the adhesive sheet obtained in step A by repeated execution is specified.

[0008] Further, the present invention relates to A pressure-sensitive adhesive sheet formed from the above pressure-sensitive adhesive composition is provided.

[0009] Further, the present invention relates to The above adhesive sheet, An optical film; The present invention provides an optical film with a pressure-sensitive adhesive sheet.

[0010] Further, the present invention relates to A step A of irradiating a laminate including, in this order, a base sheet, a coating layer including the above-mentioned pressure-sensitive adhesive composition, and a release liner with light to form a pressure-sensitive adhesive sheet from the coating layer; A step B of peeling the release liner from the pressure-sensitive adhesive sheet; Including, The method for producing a pressure-sensitive adhesive sheet includes repeatedly carrying out steps A and B using the release liner peeled off in step B, thereby reusing the release liner.

[0011] Further, the present invention relates to The present invention provides a method for producing an optical film with a pressure-sensitive adhesive sheet, the method including laminating an optical film and the pressure-sensitive adhesive sheet formed by the above-mentioned production method to form an optical film with the pressure-sensitive adhesive sheet. Effect of the Invention

[0012] According to the present invention, by reducing the amount of release liners that are discarded in the production of pressure-sensitive adhesive sheets, a pressure-sensitive adhesive composition that enables the production of pressure-sensitive adhesive sheets with low environmental impact can be provided. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a diagram for explaining a test method using the pressure-sensitive adhesive composition of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view showing a schematic diagram of a release liner used in the test method of FIG. 1. [Diagram 3] 1 is a cross-sectional view illustrating a schematic example of a pressure-sensitive adhesive sheet of the present invention. [Figure 4A] FIG. 2 is a schematic diagram for explaining a method for measuring the amount of creep for a pressure-sensitive adhesive sheet. [Figure 4B] FIG. 2 is a schematic diagram for explaining a method for measuring the amount of creep for a pressure-sensitive adhesive sheet. [Diagram 5] 1A to 1C are schematic diagrams illustrating an example of a method for producing a pressure-sensitive adhesive sheet of the present invention. [Figure 6] 1A to 1C are schematic diagrams illustrating an example of a method for producing a pressure-sensitive adhesive sheet of the present invention. [Figure 7]FIG. 1 is a cross-sectional view illustrating a schematic example of an optical film with a pressure-sensitive adhesive sheet of the present invention. [Figure 8] FIG. 1 is a cross-sectional view illustrating a schematic example of an optical film with a pressure-sensitive adhesive sheet of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The pressure-sensitive adhesive composition according to the first aspect of the present invention comprises: A photocurable pressure-sensitive adhesive composition comprising a monomer group including a (meth)acrylic monomer and / or a partial polymer of the monomer group, and a photopolymerization initiator, The pressure-sensitive adhesive composition further comprises an antioxidant, The peel strength PS1 determined by the following test is 1.0 N / 50 mm or less. Test: A laminate including, in this order, a base sheet, a coating layer including the pressure-sensitive adhesive composition, and a release liner having a release layer with a thickness of 120 nm was subjected to an illuminance of 2.42 mW / cm 2 , irradiation time 10 The adhesive sheet is formed from the coating layer in step A by irradiating the coating layer with ultraviolet light for 10 minutes, and the release liner is peeled off from the adhesive sheet in step B. The release liner is peeled off in step B, and steps A and B are repeatedly carried out to remove the release liner. The release liner is reused. The peel force PS1 between the reused release liner obtained by step B, which has been peeled off from the PSA sheet once, counting from an unused state, and the PSA sheet obtained by repeatedly performing step A is specified.

[0015] In a second aspect of the present invention, for example, in the pressure-sensitive adhesive composition according to the first aspect, the peel strength PS1 is 0.5 N / 50 mm or less.

[0016] In a third aspect of the present invention, for example, in the pressure-sensitive adhesive composition according to the first or second aspect, the peel strength PS0 between the release liner and the pressure-sensitive adhesive sheet in an unused state is 0.01 N / 50. mm or more.

[0017] In a fourth aspect of the present invention, for example in the pressure-sensitive adhesive composition according to any one of the first to third aspects, the antioxidant includes at least one selected from the group consisting of hindered phenol compounds and hindered amine compounds.

[0018] In a fifth aspect of the present invention, for example, in the pressure-sensitive adhesive composition according to any one of the first to fourth aspects, the antioxidant has a molecular weight of 1,500 or less.

[0019] In a sixth aspect of the present invention, for example, in the pressure-sensitive adhesive composition according to any one of the first to fifth aspects, the monomer group includes a carboxyl group-containing monomer.

[0020] In a seventh aspect of the present invention, for example, in the pressure-sensitive adhesive composition according to any one of the first to sixth aspects, the solvent content is 5 wt % or less.

[0021] The pressure-sensitive adhesive sheet according to the eighth aspect of the present invention is formed from the pressure-sensitive adhesive composition according to any one of the first to seventh aspects.

[0022] In a ninth aspect of the present invention, for example, the pressure-sensitive adhesive sheet according to the eighth aspect has a thickness of 5 to 40 μm.

[0023] The optical film with a pressure-sensitive adhesive sheet according to the tenth aspect of the present invention is A pressure-sensitive adhesive sheet according to the eighth or ninth aspect, An optical film; Equipped with.

[0024] In an eleventh aspect of the present invention, for example, in the pressure-sensitive adhesive sheet-attached optical film according to the tenth aspect, the optical film is a film including at least one selected from the group consisting of a polarizing film and a retardation film.

[0025] A method for producing a pressure-sensitive adhesive sheet according to a twelfth aspect of the present invention comprises the steps of: A step A of irradiating light to a laminate including, in this order, a base sheet, a coating layer including a pressure-sensitive adhesive composition according to any one of the first to seventh aspects, and a release liner to form a pressure-sensitive adhesive sheet from the coating layer; A step B of peeling the release liner from the pressure-sensitive adhesive sheet; Including, The release liner peeled off in the step B is used to repeatedly carry out the steps A and B, thereby reusing the release liner.

[0026] A method for producing an optical film with a pressure-sensitive adhesive sheet according to a thirteenth aspect of the present invention comprises the steps of: A pressure-sensitive adhesive sheet formed by the manufacturing method according to the twelfth embodiment and an optical film are laminated together. and forming an optical film with a pressure-sensitive adhesive sheet.

[0027] The present invention will be described in detail below, but the present invention is not limited to the following embodiments and can be modified in any manner without departing from the gist of the present invention.

[0028] The inventors came up with the idea of ​​further reducing the environmental impact of the PSA sheet manufacturing process by reusing release liners that were previously discarded immediately after peeling, and continued their research based on this idea, resulting in the completion of the present invention.

[0029] [Embodiment of Pressure-Sensitive Adhesive Composition] The pressure-sensitive adhesive composition of the present embodiment contains a monomer group containing a (meth)acrylic monomer and / or a partial polymer of the monomer group, and a photopolymerization initiator. The pressure-sensitive adhesive composition further contains an antioxidant. The pressure-sensitive adhesive composition is a photocurable pressure-sensitive adhesive composition that is cured by irradiation with light. In this specification, the photocurable pressure-sensitive adhesive composition may be referred to as a photocurable composition.

[0030] In one embodiment of the present invention, the pressure-sensitive adhesive composition has a peel strength PS1 determined by the following test of 1. 0N / 50mm or less. Test: A laminate including, in this order, a base sheet, a coating layer including a pressure-sensitive adhesive composition, and a release liner having a release layer with a thickness of 120 nm was subjected to an illuminance of 2.42 mW / cm 2 , 10 minutes of exposure time The method includes process A, in which an adhesive sheet is formed from the coating layer by irradiating the coating layer with ultraviolet light under certain conditions, and process B, in which the release liner is peeled off from the adhesive sheet. Processes A and B are repeated using the release liner peeled off in process B to reuse the release liner. The peel force PS1 between the reused release liner obtained in process B, which has been peeled off once from the adhesive sheet counting from an unused state, and the adhesive sheet obtained in process A by repeated application is specified. An example of a method for preparing a release liner suitable for the test is described in the Examples section.

[0031] The above test method will be described in detail below with reference to Fig. 1. First, a first laminate 10 is prepared, which includes a base sheet 11, a coating layer 12, and a release liner 13 in this order. The coating layer 12 is formed by coating an adhesive composition. The release liner 13 is disposed so that the release layer 132 (see Fig. 2) is in contact with the coating layer 12. There are no particular limitations on the base sheet 11, so long as the peel strength between the base sheet 11 and the adhesive sheet 1 formed from the coating layer 12 is greater than the peel strength between the release liner 13 and the adhesive sheet 1. Details of the base sheet 11 will be described later.

[0032] 2, the release liner 13 includes a liner substrate 131 and a release layer 132 formed on one surface of the liner substrate 131. The liner substrate 131 is, for example, a polyester film (Lumirror XD500P, thickness 75 μm). The release layer 132 is a cured layer of a release agent composition containing a silicone-based release agent as a main component. The release liner 13 is used such that the release layer 132 is on the coating layer 12 side.

[0033] The first laminate 10 can be formed, for example, by forming a coating layer 12 on a base sheet 11 (or a release liner 13), and then arranging the release liner 13 (or base sheet 11) on the formed coating layer 12. Alternatively, the first laminate 10 may be formed by applying the PSA composition in a pouring manner into the space between the base sheet 11 and the release liner 13, which are held at a predetermined distance such that their main surfaces face each other. The thickness of the coating layer 12 is typically 20 μm.

[0034] Next, the first laminate 10 is irradiated with light (ultraviolet light) 14 to form the adhesive sheet 1 from the coating layer 12 (step A). ​​As described above, the light 14 has an illuminance of 2.42 mW / cm 2 , irradiation time The first laminate 10 is irradiated with light 14 for 10 minutes. Irradiation with light 14 is typically performed from the side of the base sheet 11. The pressure-sensitive adhesive sheet 1 thus formed is left in the state where the release liner 13 is peeled off. In the illustrated embodiment, the laminate is sandwiched between the base sheet 11 and the release liner 13 to form a part of the second laminate 17.

[0035] Next, the release liner 13 is peeled off from the pressure-sensitive adhesive sheet 1 (step B). Steps A and B are repeated using the release liner 13 peeled off in step B. This allows the release liner 13 to be reused. Step A using the peeled release liner 13 is performed by forming a first laminate 10 including, in this order, a base sheet 11, a coating layer 12, and the peeled release liner 13, and irradiating the formed first laminate 10 with light 14.

[0036] Next, the peel force PS1 between the release liner 13 and the adhesive sheet 1 after it has been peeled off once from the adhesive sheet 1, counting from the unused state, is specified. In detail, the peel force PS1 is measured by the following method. First, steps A and B are performed once using an unused release liner 13. Step A is then performed a second time using the reused release liner 13 obtained in step B to obtain a second laminate 17. The second laminate 17 is cut to a width of 50 mm to prepare a test piece, and a 180° peel test is performed in which only the release liner 13 is peeled off from the prepared test piece, so that the peel force PS1 can be evaluated. The peel test is performed by peeling off the adhesive sheet 1 once. The peel test is carried out about 0.5 to 1 hour after the formation of the adhesive sheet 1. From the formation of the adhesive sheet 1 to the implementation of the peel test, the second laminate 17 and the test piece are placed in an air atmosphere at 23°C ± 5°C. The peel test is carried out at a peel speed of 300 mm / min and at a test temperature of 23°C ± 5°C. If the width of the second laminate 17 is less than 50 mm, the measured value in the original width may be converted to a value per 50 mm width. If the formation direction of the coating layer 12 can be determined, the TD perpendicular to the plane of the MD, which is the formation direction, can be determined as the width direction of the test piece. If the base sheet 11 and the release liner 13 are long, the width direction of the test piece can be determined as the width direction of the test piece.

[0037] The peeling force PS1 is, for example, 0.9 N / 50 mm or less, 0.8 N / 50 mm or less, 0 The lower limit of the peeling force PS1 may be, for example, 0.01 N / 50 mm or less, 0.02 N / 50 mm or less, 0.05 N / 50 mm or less, 0.06 N / 50 mm or less, 0.5 N / 50 mm or less, 0.4 N / 50 mm or less, 0.3 N / 50 mm or less, 0.2 N / 50 mm or less, or even 0.15 N / 50 mm or less. or more, and may be 0.03N / 50mm or more, 0.05N / 50mm or more, 0.08N / 50mm or more, or even 0.1N / 50mm or more.

[0038] In particular, in the adhesive composition of this embodiment, the peel strength PS between the release liner 13 and the adhesive sheet 1 after being peeled from the adhesive sheet 1 n times, counting from an unused state, is n(n is the number of peels An integer of 0 or more corresponding to n; when n = 0, the peel force (PS0) in the unused state is 1.0 N / 5 It is preferable that the peel strength is 0 mm or less. n using the release liner 13 described above. The step A and the step B are carried out n times, and then the step A is carried out the (n+1)th time to form a second laminate 17, which can be evaluated by carrying out the above-mentioned peel test.

[0039] As an example, the peel force PS0 between the release liner 13 and the adhesive sheet 1 in an unused state is: For example, it may be 1.0 N / 50 mm or less, 0.5 N / 50 mm or less, 0.2 N / 50 mm or less, 0.15 N / 50 mm or less, 0.12 N / 50 mm or less, 0.1 N / 50 mm or less, 0.08 N / 50 mm or less, or even 0.05 N / 50 mm or less. The peeling force PS0 may be 0.01 N / 50 mm or more, 0.02 N / 50 mm or more, or even 0.05 N / 50 mm or less. may be 0.03N / 50mm or more.

[0040] The ratio PS1 / PS0 of the peel force PS1 to the peel force PS0 may be 10 or less, 8 or less, 6 or less, or even 5 or less. The lower limit of the ratio PS1 / PS0 is, for example, 1.1 or more, and may be 2.0 or more.

[0041] As described above, the pressure-sensitive adhesive composition of the present embodiment contains a monomer group containing a (meth)acrylic monomer and / or a partial polymer of the monomer group. The content of the (meth)acrylic component in the pressure-sensitive adhesive composition, i.e., the (meth)acrylic monomer and its partial polymer, may be 50% by weight or more, 60% by weight or more, 70% by weight or more, or even 80% by weight or more. In this case, an acrylic pressure-sensitive adhesive sheet containing a (meth)acrylic polymer and its crosslinked product as the main components can be formed. In this specification, (meth)acrylic means acrylic and methacrylic. (Meth)acrylate means acrylate and methacrylate.

[0042] An example of the (meth)acrylic monomer is a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms on the side chain. The number of carbon atoms in the alkyl group may be 7 or less, 6 or less, 5 or less, or even 4 or less. The alkyl group may be linear or branched. Examples of the (meth)acrylic acid alkyl ester are 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 the like. acrylate, 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. The (meth)acrylic acid alkyl ester may be n-butyl (meth)acrylate.

[0043] The content of the (meth)acrylic acid alkyl ester in the monomer group is, for example, 40% by weight or more, and may be 50% by weight or more, 60% by weight or more, 70% by weight or more, 80% by weight or more, 85% by weight or more, 90% by weight or more, or even 95% by weight or more. In calculating the content, the weight of the partially polymerized product is converted into the weight of each monomer before polymerization.

[0044] The monomer group may contain a carboxyl group-containing monomer. The carboxyl group-containing monomer may be a (meth)acrylic monomer, in other words, the (meth)acrylic monomer may contain a carboxyl group-containing monomer. Examples of the carboxyl group-containing monomer are (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. The content of the carboxyl group-containing monomer in the monomer group may be, for example, 10% by weight or less, 9% by weight or less, 8% by weight or less, 7% by weight or less, 6% by weight or less, 5.5% by weight or less, or even 5% by weight or less. The lower limit of the content may be, for example, 0.1% by weight or more, 0.5% by weight or more, or even 1% by weight or more. The monomer group may not contain a carboxyl group-containing monomer.

[0045] The monomer group may contain a hydroxy group-containing monomer. The hydroxy group-containing monomer may be a (meth)acrylic monomer, in other words, the (meth)acrylic monomer may contain a hydroxy group-containing monomer. The hydroxy group-containing monomer may contribute to improving the cohesive strength of the pressure-sensitive adhesive sheet. Examples of the hydroxy group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 1-hydroxypropyl (meth)acrylate. 2-hydroxylauryl and (4-hydroxymethylcyclohexyl)-methyl acrylate. The hydroxy group-containing monomer is preferably 2-hydroxyethyl (meth)acrylate or 4-hydroxybutyl (meth)acrylate. The content of the hydroxy group-containing monomer in the monomer group is, for example, 10% by weight or less, and may be 5% by weight or less, 4% by weight or less, 3% by weight or less, 2% by weight or less, 1% by weight or less, 0.8% by weight or less, 0.5% by weight or less, 0.3% by weight or less, 0.2% by weight or less, or even 0.1% by weight or less. The lower limit of the content is, for example, 0.01% by weight or more, 0.03% by weight or more, or even 0.05% by weight or more. The monomer group may not contain a hydroxy group-containing monomer.

[0046] In the pressure-sensitive adhesive composition, each of the above-mentioned monomers may be contained as a partial polymer. The partial polymer may be either a homopolymer or a copolymer. The partial polymer can contribute to the stable formation of a coating layer by appropriately increasing the viscosity of the pressure-sensitive adhesive composition.

[0047] As described above, the pressure-sensitive adhesive composition further contains a photopolymerization initiator. An example of the photopolymerization initiator is a photoradical generator that generates radicals when exposed to visible light and / or ultraviolet light having a wavelength shorter than 450 nm.

[0048] Examples of photopolymerization initiators include benzoin ethers such as benzoin methyl ether, benzoin isopropyl ether, and benzil dimethyl ketal; substituted benzoin ethers such as anisole methyl ether; substituted acetophenones such as 2,2-diethoxyacetophenone and 2,2-dimethoxy-2-phenylacetophenone; α-hydroxyalkylphenones such as 1-hydroxycyclohexyl-phenyl ketone; substituted alpha-ketol such as 2-methyl-2-hydroxypropiophenone; aromatic sulfonyl chlorides such as 2-naphthalenesulfonyl chloride; photoactive oximes such as 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime; and benzophenone compounds such as benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, acrylated benzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, and 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone. Thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, 2,4-diethylthioxanthone and other thioxanthone compounds; 2,4,6-trichloro-s-triazine, 2-phenyl-4,6-bis(trichloromethyl)-s-triazine, 2-(p-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(p-tolyl)-4,6-bis(trichloromethyl)-s-triazine , 2-piperonyl-4,6-bis(trichloromethyl)-s-triazine, 2,4-bis(trichloromethyl)-6-styryl-s-triazine, 2-(naphth-1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4-methoxy-naphth-1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2,4-trichloromethyl-(piperonyl)-6-triazine, 2,4-trichloromethyl-(4'-methoxystyryl)-6-triazine and other triazine-based compounds;Oxime ester compounds such as 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyloxime)], O-(acetyl)-N-(1-phenyl-2-oxo-2-(4'-methoxy-naphthyl)ethylidene)hydroxylamine; phosphine compounds such as bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide; quinone compounds such as 9,10-phenanthrenequinone, camphorquinone, ethylanthraquinone; borate compounds; carbazole compounds; imidazole compounds; and titanocene compounds. The pressure-sensitive adhesive composition may contain one or more photopolymerization initiators.

[0049] The amount of the photopolymerization initiator in the pressure-sensitive adhesive composition is, for example, 0.02 to 10 parts by weight, and may be 0.05 to 5 parts by weight, based on 100 parts by weight in total of the monomer group and its partial polymer.

[0050] As described above, the pressure-sensitive adhesive composition further contains an antioxidant. The antioxidant is a component suitable for adjusting the peel force PS1 to a small value. In detail, in step A of the above test, In this case, a chemical bond is formed between the release liner 13 and the adhesive sheet 1 by irradiation with light 14, and a part of this bond or a functional group formed by decomposition of the bond may remain on the surface of the release liner 13 even after the adhesive sheet 1 is peeled off. As a result, the peeling force of the release liner 13 from the adhesive sheet 1 tends to be greater after step A is performed than before step A. The antioxidant tends to suppress the formation of a chemical bond between the release liner 13 and the adhesive sheet 1. Furthermore, the antioxidant also tends to suppress the surface of the release liner from being contaminated by the material of the adhesive sheet, regardless of the manufacturing conditions of the adhesive sheet (such as the light irradiation time).

[0051] Examples of the antioxidant include phenolic compounds (particularly hindered phenolic compounds), amine compounds (particularly hindered amine compounds), and phosphorus compounds. The antioxidant preferably contains at least one selected from the group consisting of hindered phenolic compounds and hindered amine compounds, and more preferably contains a hindered phenolic compound. The compound contained in the antioxidant may not contain a sulfur atom. The pressure-sensitive adhesive composition may contain one or more antioxidants.

[0052] Examples of the hindered phenol compounds include dibutylhydroxytoluene (BHT), pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (BASF "Irganox 1010"), octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (BASF "Irganox 1076"), isooctyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (BASF "Irganox 1135"), 3,3',3'',5,5',5''-hexa-tert-butyl-a,a',a''-(mesitylene-2,4,6-triyl)tri-p-cresol (BASF "Irganox 1135"). 1330"), 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (BASF "Irganox 3114"), tris[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxyethyl]isocyanurate (BASF "Irganox 3125"), pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] (ADEKA "ADEKA STAB AO-60"), 3,9-bis{2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane (ADEKA "ADEKA STAB AO-80"), 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate (Sumitomo Chemical "Sumilizer GS"), 2-tert-butyl-4-methyl-6-(2-hydroxy-3-tert-butyl-5-methylbenzyl)phenyl acrylate (Sumitomo Chemical "Sumilizer GM"), 2,2'-dimethyl-2,2'-(2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diyl)dipropane-1,1'-diyl=bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propanoate] (Sumitomo Chemical's "Sumilizer GA-80"), 1,3,5-tris(3-hydroxy-4-tert-butyl-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (Cyanox 1790) manufactured by Cytec, etc. The hindered phenol compound is preferably Irga. Nox 1010, Irganox 1135, and more preferably Irganox 1135.

[0053] Examples of hindered amine compounds include bis-(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate (BASF's "Tinuvin 123"), tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylate (ADEKA's "Adeka STAB LA-52"), tetrakis(2,2,6,6-tetramethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylate (ADEKA's "Adeka STAB LA-57"), 1,2,3,4-butane tetracarboxylic acid tetramethyl ester 1,2,2,6,6-pentamethyl-4-piperidinol β,β,β',β'-Tetramethyl-2,4,8,10-tetraoxaspiro[5,5]undecane-3,9-diethanol (ADEKA "ADEKA STAB LA-63P"), 1,2,3,4-butanetetracarboxylic acid tetramethyl ester 2,2,6,6-pentamethyl-4-piperidinol β,β,β',β'-Tetramethyl-2,4,8,10-tetraoxaspiro[5,5]undecane-3,9-diethanol (ADEKA Corp. "ADEKA STAB LA-68"), bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate (ADEKA Corp. "ADEKA STAB LA-72"), bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate (ADEKA Corp. "ADEKA STAB LA-77Y"), bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate (ADEKA Corp. "ADEKA STAB LA-77G"), bis(1-undecanoxy-2,2,6,6-tetramethyl-4-piperidyl)sebacate (ADEKA Corp. "ADEKA STAB LA-77G"), tetramethylpiperidin-4-yl) carbonate (ADEKA "ADEKA STAB LA-81"), 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate (ADEKA "ADEKA STAB LA-82"), 2,2,6,6-tetramethyl-4-piperidyl methacrylate (ADEKA "ADEKA STAB LA-87"), SONGLIGHT1190 (SONGWON), SONGLIGHT1230 (SONGWON), bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate (SONGWON "SONGLIGHT2920"), bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate (SONGWON "SONGLIGHT7700"), poly(4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol-ortho-1,4-butanediic acid) (BASF "Uvinul5062H"), Uvinul5050H (BASF), N,N'-bisformyl-N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-hexamethylenediamine (BASF "Uvinul4050H"), bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate (BASF "Uvinul4077H"), etc. are included. The hindered amine compound is preferably Adeka STAB LA-52.

[0054] Examples of phosphorus compounds include trioctyl phosphite, trilauryl phosphite, tris tridecyl phosphite, tris isodecyl phosphite, phenyl diisooctyl phosphite, phenyl diisodecyl phosphite, phenyl di(tridecyl)phosphite, diphenyl isooctyl phosphite, diphenyl isodecyl phosphite, diphenyl tridecyl phosphite, triphenyl phosphite, tris(nonylphenyl)phosphite, tris(2,4-di-t-butylphenyl)phosphite, tris(butoxyethyl)phosphite, and tetratridecyl -4,4'-butylidenebis(3-methyl-6-t-butylphenol)-diphosphite, 4,4'-isopropylidene-diphenol alkyl phosphite (where the alkyl has 12 to 15 carbon atoms), 4,4'-isopropylidenebis(2-t-butylphenol)·di(nonylphenyl)phosphite, tris(biphenyl)phosphite, tetra(tridecyl)-1,1,3-tris(2-methyl-5-t-butyl-4-hydroxyphenyl)butane diphosphite, tris(3,5-di-t-butyl-4-hydroxyphenyl)phosphite, hydrogenated-4,4'- Isopropylidenediphenol polyphosphite, bis(octylphenyl)·bis[4,4'-butylidenebis(3-methyl-6-t-butylphenol)]·1,6-hexanediol diphosphite, hexatridecyl-1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenol) diphosphite, tris[4,4'-isopropylidenebis(2-t-butylphenol)] phosphite, tris(1,3-distearoyloxyisopropyl)phosphite, 9,10-dihydro-9-phosphaphenanthrene-10-oxide, tetrahydrofuran Examples of such diphosphite include rakis(2,4-di-t-butylphenyl)-4,4'-biphenylene diphosphonite, distearyl pentaerythritol diphosphite, di(nonylphenyl)pentaerythritol diphosphite, phenyl-4,4'-isopropylidenediphenol-pentaerythritol diphosphite, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite, and phenylbisphenol-A-pentaerythritol diphosphite.

[0055] The antioxidant preferably has a small molecular weight. By using an antioxidant with a small molecular weight, it is easy to adjust the peeling force PS1 to a smaller value. It is preferable that the antioxidant is a liquid at room temperature (25° C.) because the antioxidant has a molecular weight of, for example, 1500 or less, and may be 1000 or less, 800 or less, 500 or less, or even 400 or less. The lower limit of the molecular weight of the antioxidant is not particularly limited, and may be, for example, 100 or more, 200 or more, or even 300 or more.

[0056] The amount of the antioxidant is, for example, 0.01 parts by weight or more, and may be 0.05 parts by weight or more, 0.1 parts by weight or more, or even 0.3 parts by weight or more, based on 100 parts by weight in total of the monomer group and its partial polymer. The upper limit of the amount of the antioxidant is, for example, 5 parts by weight or less, and may be 3 parts by weight or less, 2 parts by weight or less, 1 part by weight or less, or even 0.5 parts by weight or less.

[0057] The pressure-sensitive adhesive composition may contain a crosslinking agent. An example of the crosslinking agent is a polyfunctional monomer having two or more polymerizable functional groups in one molecule. The polyfunctional monomer may be a (meth)acrylic monomer. An example of the polyfunctional monomer is a monomer having two or more C=C bonds in one molecule, and a monomer having one or more C=C bonds and one or more polymerizable functional groups such as epoxy groups, aziridine groups, oxazoline groups, hydrazine groups, methylol groups, etc. in one molecule. The polyfunctional monomer is preferably a monomer having two or more C=C bonds in one molecule.

[0058] Examples of crosslinking agents include (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,2-ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol diacrylate (NDD A), polyfunctional acrylates such as 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and tetramethylolmethane tri(meth)acrylate (such as ester compounds of polyhydric alcohols and (meth)acrylic acid); allyl (meth)acrylate, vinyl (meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butyl di(meth)acrylate, and hexyl di(meth)acrylate. The polyfunctional monomer is preferably a polyfunctional acrylate, and more preferably trimethylolpropane tri(meth)acrylate, hexanediol di(meth)acrylate, and dipentaerythritol hexa(meth)acrylate.

[0059] The amount of crosslinking agent used varies depending on the molecular weight and number of functional groups, but it is generally For example, the amount is 5 parts by weight or less, 3 parts by weight or less, 2 parts by weight or less, 1 part by weight or less, or even 0.5 parts by weight or less, relative to 100 parts by weight of the total of the above. The lower limit of the blending amount is, for example, 0.01 parts by weight or more, or even 0.05 parts by weight or more.

[0060] The pressure-sensitive adhesive composition may contain additives other than those described above. Examples of the additives include a chain transfer agent, a silane coupling agent, a viscosity modifier, a tackifier, a plasticizer, a softener, an antiaging agent, a filler, a colorant, a surfactant, an antistatic agent, and an ultraviolet absorbing agent.

[0061] The content of the solvent in the pressure-sensitive adhesive composition is, for example, 5% by weight or less, and may be 4% by weight or less, 3% by weight or less, 2% by weight or less, 1% by weight or less, or even 0.5% by weight or less. The pressure-sensitive adhesive composition may be substantially free of a solvent. The phrase "substantially free of a solvent" means that the solvent derived from additives or the like is allowed to be present at a content of, for example, 0.1% by weight or less, preferably 0.05% by weight or less, more preferably 0.01% by weight or less.

[0062] The viscosity of the pressure-sensitive adhesive composition is preferably 5 to 100 poise. A pressure-sensitive adhesive composition having a viscosity in the above range is particularly suitable for forming a coating layer.

[0063] [Embodiment of the adhesive sheet] An example of the pressure-sensitive adhesive sheet 1 of the present embodiment is shown in Fig. 3. The pressure-sensitive adhesive sheet 1 is formed from the pressure-sensitive adhesive composition described above. The pressure-sensitive adhesive sheet 1 may be laminated with the base sheet and release liner used in the production thereof.

[0064] The polymerization rate of the monomer group in the pressure-sensitive adhesive sheet 1 is preferably 90% or more. The polymerization rate may be 95% or more, 98% or more, or even 99% or more.

[0065] The gel fraction of the pressure-sensitive adhesive sheet 1 is, for example, 50% or more, and may be 75% or more, 80% or more, or even 85% or more.

[0066] The creep amount of the pressure-sensitive adhesive sheet 1 is, for example, 180 μm or less, and may be 160 μm or less. The lower limit of the creep amount is, for example, 5 μm or more, and may be 10 μm or more.

[0067] The creep amount of the adhesive sheet 1 can be evaluated as follows (see FIG. 4A and FIG. 4B). First, a laminate of the adhesive sheet 1 to be evaluated and the support film 51 is cut into a rectangular shape of 10 mm×50 mm to prepare a test piece 52. The support film 51 is arranged for the purpose of suppressing deformation of the portion of the adhesive sheet 1 to which the load is applied during the test, thereby enabling more accurate measurement of the creep amount. For the support film 51, for example, a resin film such as a polyethylene terephthalate (PET) film can be used. The support film 51 may be an optical film or a laminate including an optical film. The thickness of the support film 51 may be any thickness that does not deform itself under the load, and is, for example, 20 to 200 μm. Next, as shown in FIG. 4A and FIG. 4B, the test piece 52 is attached to the surface of a stainless steel test plate 53 by the adhesive sheet 1 at a joint surface of 10 mm long×10 mm wide. FIG. 4B shows the cross section BB of FIG. 4A. The test piece 52 is attached to the test plate 53 so that no air bubbles are mixed between the test plate 53 and the adhesive sheet 1. After attachment, the test plate 53 and the adhesive sheet 1 are placed in an autoclave at 50°C and 5 atm (absolute pressure) for 15 minutes to homogenize the bond between the test plate 53 and the adhesive sheet 1. Next, the test plate 53 and the test piece 52 are held vertically with the test plate 53 facing upward and left in an atmosphere at 25°C for at least 5 minutes, and then a weight of 500g is fixed to the center of the lower end of the test piece 52 with the test plate 53 fixed, and a load 54 of 500gf is applied vertically downward. The creep amount (displacement amount) of the adhesive sheet 1 relative to the test plate 53 at a time 3600 seconds after the load 54 is started to be applied is measured as the fall amount of the weight. A laser displacement meter can be used to measure the fall amount of the weight.

[0068] The thickness of the pressure-sensitive adhesive sheet 1 is, for example, 2 to 70 μm, and may be 2 to 50 μm, 5 to 40 μm, 10 to 30 μm, 10 to 25 μm, or even 10 to 20 μm.

[0069] The pressure-sensitive adhesive sheet 1 is, for example, a pressure-sensitive adhesive composition for determining the above-mentioned peel force PS1. It can be prepared by the same method as that described for the test. In detail, as shown in FIG. 1, first, a first laminate 10 including a base sheet 11, a coating layer 12 containing a pressure-sensitive adhesive composition, and a release liner 13 in this order is irradiated with light 14 to form a pressure-sensitive adhesive sheet 1 from the coating layer 12 (step A). ​​Irradiation with light 14 is typically performed from the side of the base sheet 11. The light 14 penetrates the base sheet 11 to reach the coating layer 12, and hardens the coating layer 12. However, irradiation with light 14 may be performed from the side of the release liner 13, or from both the side of the release liner 13 and the base sheet 11. The formed pressure-sensitive adhesive sheet 1 is sandwiched between the base sheet 11 and the release liner 13 until the release liner 13 is peeled off, constituting a part of the second laminate 17. After step A, the release liner 13 is peeled off from the pressure-sensitive adhesive sheet 1 (step B). 1, steps A and B are repeatedly performed using the release liner 13 peeled off in step B. This allows the release liner 13 to be reused. Step A using the peeled release liner 13 is performed by forming a first laminate 10 including, in this order, a base sheet 11, a coating layer 12, and the peeled release liner 13, and irradiating the formed first laminate 10 with light 14.

[0070] As described above, the pressure-sensitive adhesive composition of the present embodiment has a peel strength PS1 of 1.0 N / 50 m m or less. With such a pressure-sensitive adhesive composition, even when steps A and B are repeatedly performed using the release liner 13 peeled off in step B during the production of the pressure-sensitive adhesive sheet 1, there is a tendency for an increase in the peel force of the release liner 13 with respect to the pressure-sensitive adhesive sheet 1 to be suppressed. Because the release liner 13 can be reused repeatedly, the amount of release liner 13 that is discarded can be reduced, and the pressure-sensitive adhesive sheet 1 can be produced with low environmental impact.

[0071] <Process A> (Release liner) An example of the liner substrate of the release liner 13 is a resin film. Examples of resins that can be contained in the liner substrate are polyesters such as polyethylene terephthalate and polyethylene naphthalate, acetate resins, polyethersulfone, polycarbonate, polyamide, polyimide, polyolefin, (meth)acrylic resins, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl alcohol, polyarylate, and polyphenylene sulfide. The resin is preferably a polyester such as polyethylene terephthalate.

[0072] The release liner 13 may have a transmittance for the light 14 irradiated in step A, or may have the same degree of transmittance for the light 14 as the base sheet 11 .

[0073] The thickness of the release liner 13 is, for example, 10 to 200 μm, and may be 25 to 150 μm.

[0074] The release liner 13 may include a layer other than the liner substrate. The release liner 13 may include a release layer. The release liner 13 in Fig. 2 includes a liner substrate 131 and a release layer 132 formed on one surface of the liner substrate 131. The release liner 13 in Fig. 2 can be used such that the release layer 132 is on the coating layer 12 side.

[0075] The release layer 132 is typically a cured layer of a release agent composition containing a release agent. Examples of the release agent include silicone-based release agents, fluorine-based release agents, long-chain alkyl-based release agents, and fatty acid amide-based release agents. Various release agents such as silica powder can be used. The release liner 13 may be provided with a cured layer of a release agent composition containing a silicone-based release agent as a main component (hereinafter referred to as "silicone release layer"). The silicone release layer is particularly suitable for achieving both good adhesion to the pressure-sensitive adhesive sheet 1 and good releasability. In this specification, the term "main component" refers to the component with the largest content.

[0076] The silicone-based release agent is, for example, various curable silicone materials such as addition reaction type, condensation reaction type, ultraviolet curable type, electron beam curable type, and solventless type, and an addition reaction curable silicone material is preferred. An addition reaction curable silicone material is particularly suitable for forming a release layer that has both adhesion and releasability to the pressure-sensitive adhesive sheet 1. The curable silicone material may be a silicone-modified resin in which reactive silicone is introduced into an organic resin such as urethane, epoxy, or alkyd resin by graft polymerization or the like.

[0077] An example of the addition reaction curing silicone material is a polyorganosiloxane having a vinyl group or an alkenyl group in the molecule. The addition reaction curing silicone material may not have a hydrosilyl group. Examples of the alkenyl group are 3-butenyl, 4-pentenyl, 5-hexenyl, 6-heptenyl, 7-octenyl, 8-nonenyl, 9-decenyl, 10-undecenyl, and 11-dodecenyl. Examples of the polyorganosiloxane are polyalkylalkylsiloxanes such as polydimethylsiloxane, polydiethylsiloxane, and polymethylethylsiloxane, polyalkylarylsiloxane, and copolymers of multiple types of Si atom-containing monomers such as poly(dimethylsiloxane-diethylsiloxane). The polyorganosiloxane is preferably polydimethylsiloxane.

[0078] A release agent composition containing a silicone-based release agent as a main component (hereinafter referred to as "silicone release agent composition") usually contains a crosslinking agent. An example of the crosslinking agent is polyorganosiloxane having a hydrosilyl group. The crosslinking agent may have two or more hydrosilyl groups in one molecule.

[0079] The silicone release agent composition may contain a curing catalyst. An example of the curing catalyst is a platinum catalyst. An example of the platinum catalyst is chloroplatinic acid, an olefin complex of platinum, or an olefin complex of chloroplatinic acid. The amount of the platinum catalyst used is, for example, 10 to 1000 ppm (weight basis, platinum equivalent) based on the total solid content of the composition.

[0080] The silicone release agent composition may contain additives. Examples of additives are release control agents and adhesion promoters. Examples of release control agents are unreactive silicone resins, and more specific examples are organosiloxanes such as octamethylcyclotetrasiloxane, and MQ resins. The amount of the release control agent and adhesion promoter used is, for example, 1 to 30% by weight in total based on the total solid content of the composition. Further examples of additives are fillers, antistatic agents, antioxidants, ultraviolet absorbers, plasticizers, and colorants. The amount of the further additives used is, for example, 10% by weight or less in total based on the total solid content of the composition.

[0081] The silicone release agent composition may contain an organic solvent. Examples of the organic solvent include hydrocarbon solvents such as cyclohexane, n-hexane, and n-heptane; aromatic solvents such as toluene and xylene; ester solvents such as ethyl acetate and methyl acetate; ketone solvents such as acetone and methyl ethyl ketone; and alcohol solvents such as methanol, ethanol, and butanol. Two or more organic solvents may be contained. The amount of the organic solvent used is preferably 80 to 99.9% by weight of the silicone release agent composition.

[0082] The release layer 132 can be formed, for example, by heating and drying a coating film containing a release agent composition formed on the liner substrate 131. The release agent composition can be applied by 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, etc. Various coating methods such as precoating and die coating can be applied. For heating and drying, for example, hot air drying can be applied. The heating temperature and time vary depending on the heat resistance of the liner substrate, but are usually about 80 to 150°C and 10 seconds to 10 minutes. If necessary, irradiation with active energy rays such as ultraviolet rays may be used in combination.

[0083] The thickness of the release layer 132 is, for example, 10 to 300 nm. The upper limit of the thickness may be 200 nm or less, 150 nm or less, 120 nm or less, 110 nm or less, 100 nm or less, less than 100 nm, 90 nm or less, 80 nm or less, 70 nm or less, less than 70 nm, or even 65 nm or less. The lower limit of the thickness may be 15 nm or more, 20 nm or more, 25 nm or more, 30 nm or more, 35 nm or more, 40 nm or more, 45 nm or more, or even 50 nm or more. The thickness of the release layer 132 may be 110 nm or less, in other words, the release liner 13 may have the release layer 132 on the surface on the side of the coating layer 12, and the thickness of the release layer 132 may be 110 nm or less.

[0084] The release liner 13 may be in the form of a sheet or a continuous piece.

[0085] (Base sheet) An example of the base sheet 11 is a resin film. Examples of the resin contained in the base sheet 11 are the same as the examples of the resin that can be contained in the liner base material.

[0086] The base sheet 11 preferably has excellent transmittance for the light 14 irradiated in the step A.

[0087] The thickness of the base sheet 11 is, for example, 10 to 200 μm, and may be 25 to 150 μm.

[0088] The base sheet 11 may have a release layer on the surface on the side of the coating layer 12. Examples of the release layer that the base sheet 11 may have and the manufacturing method thereof are the same as the examples of the release layer that the release liner 13 may have and the manufacturing method thereof. Both the release liner 13 and the base sheet 11 may have a release layer. In this case, both release layers may be formed from a release agent composition containing the same release agent as a main component. In addition, the thicknesses of both release layers may be different, and for example, the release layer provided on the base sheet 11 may be thicker.

[0089] For the base sheet 11, a sheet having a greater peeling strength from the adhesive sheet 1 than the release liner 13 can usually be selected.

[0090] The base sheet 11 may be in the form of a sheet or a continuous length.

[0091] (First laminate and its formation) The first laminate 10 may include an additional layer other than the base sheet 11, the coating layer 12, and the release liner 13. The additional layer may be disposed on the side of the base sheet 11 and / or the release liner 13 opposite to the side of the coating layer 12. The coating layer 12 is preferably in contact with the base sheet 11 and the release liner 13.

[0092] The first laminate 10 can be formed, for example, by forming a coating layer 12 on a base sheet 11 (or a release liner 13) and then arranging a release liner 13 (or a base sheet 11) on the formed coating layer 12. Alternatively, the first laminate 10 may be formed by applying a pressure-sensitive adhesive composition by pouring it into the space between the base sheet 11 and the release liner 13 that are held at a predetermined distance so that their main surfaces face each other. The peeled release liner 13 may be used such that the surface that was on the side of the coating layer 12 in step A immediately before peeling, for example the surface on the release layer 132 side, becomes the side of the coating layer 12 again.

[0093] The coating layer 12 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.

[0094] The thickness of coating layer 12 can be adjusted depending on the intended thickness of pressure-sensitive adhesive sheet 1, and may be, for example, 5 to 100 μm, 5 to 50 μm, 5 to 25 μm, or even 5 to 20 μm.

[0095] The first laminate 10 may include a long base sheet 11, a long coating layer 12, and a long release liner 13, in other words, may be long. The long first laminate 10 can be obtained, for example, by forming the coating layer 12 between the base sheet 11 and the release liner 13 while conveying them, the base sheet 11 and the release liner 13 being unwound from a roll.

[0096] (Light irradiation) The light 14 irradiated to the first laminate 10 is, for example, visible light or ultraviolet light having a wavelength shorter than 450 nm. The light 14 may contain light having a wavelength in the same region as the absorption wavelength of the photopolymerization initiator contained in the pressure-sensitive adhesive composition. The light 14 may be irradiated with light having a short wavelength of 300 nm or less cut by a filter or the like, and cutting the short wavelength light is suitable for suppressing deterioration of the base sheet 11 caused by the light 14. The light source of the light 14 is, for example, a light irradiation device equipped with an ultraviolet irradiation lamp. Examples of the ultraviolet irradiation lamp are ultraviolet LED, low pressure mercury lamp, medium pressure mercury lamp, high pressure mercury lamp, ultra-high pressure mercury lamp, metal halide lamp, xenon lamp, microwave excited mercury lamp, black light lamp, chemical lamp, germicidal lamp, low pressure discharge mercury lamp, and excimer laser. Two or more ultraviolet irradiation lamps may be combined.

[0097] The illumination with light 14 may be continuous or intermittent.

[0098] The illuminance of the light 14 is, for example, 1 to 20 mW / cm 2 The irradiation time of the light 14 is, for example, 5 The integrated amount of light 14 on the first laminate 10 is, for example, 100 to 5000 mJ / cm 2 It is.

[0099] <Process B> In step B, the release liner 13 is peeled off from the cured second laminate 17. The second laminate 17 includes, in this order, a base sheet 11, an adhesive sheet 1, and a release liner 13. By the above peeling, a third laminate 15 including the release liner 13, and the base sheet 11 and the adhesive sheet 1 is obtained.

[0100] The peel strength between release liner 13 and adhesive sheet 1 is smaller than, for example, the peel strength between base sheet 11 and adhesive sheet 1. The peel strength of base sheet 11 from adhesive sheet 1 is, for example, 0.1 to 10 N / 50 mm, and may be 1 to 8 N / 50 mm, 2 to 7 N / 50 mm, or even 3 to 5 N / 50 mm.

[0101] The number of times that release liner 13 is peeled off and reused in the production of pressure sensitive adhesive sheet 1 is not particularly limited, and may be, for example, 3 or more times, 5 or more times, or even 7 or more times.

[0102] The peeled release liner 13 may be wound into a roll and then reused.

[0103] Next, another example of a method for producing the adhesive sheet 1 will be described with reference to Fig. 5. In this example, a coating device 32 applies a coating agent to one side of the long base sheet 11 unwound from a roll 31. A coating layer 12 of the pressure-sensitive adhesive composition is formed. Next, a long release liner 13 unwound from a roll 33 is placed on the coating layer 12 to form a long first laminate 10. Next, light 14 is irradiated from a light irradiation device 34 to the first laminate 10 to form a long adhesive sheet 1. Next, the release liner 13 is peeled from a second laminate 17 containing the adhesive sheet 1 and wound up into a roll 35. The above steps are performed while the base sheet 11 and the release liner 13 are being transported. The wound up release liner 13 is reused. The method of FIG. 5 is particularly suitable for mass production of adhesive sheets 1.

[0104] Another example of the method for producing the adhesive sheet 1 will be described with reference to Fig. 6. This example is the same as the example of Fig. 5, except that the release liner 13 peeled off from the second laminate 17 is reused in the production of the adhesive sheet 1 without being wound up into a roll 35. The method of Fig. 6 is particularly suitable for mass production of the adhesive sheet 1.

[0105] [Embodiment of Optical Film with Adhesive Sheet] An example of the optical film with an adhesive sheet of this embodiment is shown in Fig. 7. The optical film with an adhesive sheet 20A in Fig. 7 includes an adhesive sheet 1 and an optical film 2. The adhesive sheet 1 may be in direct contact with the optical film 2, or indirect contact with the optical film 2. The optical film with an adhesive sheet 20A may have a structure in which the base sheet used in producing the adhesive sheet 1 is laminated on the adhesive sheet 1.

[0106] The optical film 2 is, for example, a film including at least one selected from the group consisting of a polarizing film and a retardation film. The optical film 2 may be a laminated film including a polarizing film and / or a retardation film. The optical film 2 may include a glass film. However, the optical film 2 is not limited to the above examples.

[0107] The polarizing film includes a polarizer. The polarizing film typically includes a polarizer and a protective film (transparent protective film). The protective film is disposed, for example, in contact with the main surface (surface having the widest area) of the polarizer. The polarizer may be disposed between two protective films. The protective film may be disposed on at least one surface of the polarizer.

[0108] The polarizer is not particularly limited, and examples thereof include hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and partially saponified ethylene-vinyl acetate copolymer films, which are uniaxially stretched after adsorbing dichroic substances such as iodine and dichroic dyes; polyene-based oriented films such as dehydrated polyvinyl alcohol and dehydrochlorinated polyvinyl chloride; etc. Polarizers are typically made of polyvinyl alcohol films (polyvinyl alcohol films include partially saponified ethylene-vinyl acetate copolymer films) and dichroic substances such as iodine.

[0109] The thickness of the polarizer is not particularly limited, and may be, for example, 80 μm or less, 50 μm or less, 30 μm or less, 25 μm or less, or even 20 μm or less. The lower limit of the thickness of the polarizer is not particularly limited, and may be, for example, 1 μm or more, 5 μm or more, 10 μm or more, or even 15 μm or more. A thin polarizer (for example, a thickness of 20 μm or less) is suppressed in dimensional change, and can contribute to improving the durability of the optical laminate, particularly the durability at high temperatures.

[0110] As the material for the protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture blocking property, isotropy, etc. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, cyclic polyolefin resins (norbornene-based resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and the like. Examples of the material of the protective film include a mixture of these. The material of the protective film may be a thermosetting resin or an ultraviolet-curing resin such as a (meth)acrylic resin, a urethane resin, an acrylic urethane resin, an epoxy resin, or a silicone resin. When the polarizing film has two protective films, the materials of the two protective films may be the same as each other or different from each other. For example, a protective film made of a thermoplastic resin may be attached to one main surface of the polarizer via an adhesive, and a protective film made of a thermosetting resin or an ultraviolet-curing resin may be attached to the other main surface of the polarizer. The protective film may contain one or more types of optional additives. Examples of the additives include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a release agent, a coloring inhibitor, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a colorant.

[0111] The thickness of the protective film can be appropriately determined, but is generally about 10 to 200 μm in terms of strength, workability such as handleability, thinness, and the like.

[0112] The polarizer and the protective film are usually adhered to each other via a water-based adhesive or the like. Examples of the water-based adhesive include an isocyanate-based adhesive, a polyvinyl alcohol-based adhesive, a gelatin-based adhesive, a vinyl-based latex, a water-based polyurethane, and a water-based polyester. Examples of adhesives other than the above-mentioned adhesives include an ultraviolet-curable adhesive and an electron beam-curable adhesive. The electron beam-curable polarizing plate adhesive exhibits suitable adhesion to various protective films. The adhesive may contain a metal compound filler.

[0113] In the polarizing film, a retardation film or the like can be formed on the polarizer instead of the protective film. Another protective film or a retardation film or the like can be further provided on the protective film.

[0114] The protective film may have a hard coat layer on the surface opposite to the surface bonded to the polarizer, and may also be subjected to treatments for the purposes of anti-reflection, anti-sticking, diffusion, anti-glare, etc.

[0115] The polarizing film may be a circular polarizing film.

[0116] The retardation film may be one obtained by stretching a polymer film or one obtained by aligning and fixing a liquid crystal material. The retardation film has birefringence, for example, in the in-plane and / or thickness direction.

[0117] Retardation films include anti-reflection retardation films (see JP 2012-133303 A,

[0221] ,

[0222] ,

[0228] ), viewing angle compensation retardation films (see JP 2012-133303 A,

[0225] ,

[0226] ), and tilted orientation retardation films for viewing angle compensation (see JP 2012-133303 A,

[0227] ).

[0118] The specific configuration of the retardation film, for example, the retardation value, arrangement angle, three-dimensional birefringence, whether it is a single layer or a multilayer, and the like, are not particularly limited, and any known retardation film can be used.

[0119] The thickness of the retardation film is preferably 20 μm or less, more preferably 10 μm or less, further preferably 1 to 9 μm, and particularly preferably 3 to 8 μm.

[0120] The retardation film may include, for example, a quarter wave plate and / or a half wave plate in which a liquid crystal material is aligned and fixed.

[0121] The optical film 20A with a pressure-sensitive adhesive sheet includes, for example, a base sheet 11, a pressure-sensitive adhesive sheet 1, and The second laminate 17 includes the release liner 13 in this order, and the optical film 2 is placed on the exposed surface of the pressure-sensitive adhesive sheet 1 formed by peeling the release liner 13 from the second laminate 17, and the pressure-sensitive adhesive sheet 1 and the optical film 2 are laminated together to form the second laminate 17. The second laminate 17 can be formed by the above-mentioned step A. The peeling of the release liner 13 may be performed as the above-mentioned step B.

[0122] Another example of the optical film with an adhesive sheet of the present embodiment is shown in Fig. 8. The optical film with an adhesive sheet 20B in Fig. 8 has a laminated structure in which an adhesive sheet 1A, an optical film 2A, an adhesive sheet 1B, and an optical film 2B are laminated in this order. The optical film with an adhesive sheet 20B may have a structure in which the base sheet used in producing the adhesive sheet 1A is laminated on the adhesive sheet 1A.

[0123] In the optical film 20B with adhesive sheet, typically, the optical film 2A is a retardation film, and the optical film 2B is a polarizing film. The adhesive sheet 1B functions as an interlayer adhesive between the optical films 2A and 2B. The adhesive sheet 1B may be made of a known adhesive.

[0124] The optical film with a pressure-sensitive adhesive sheet of this embodiment can be distributed and stored, for example, as a roll of a strip-shaped optical film with a pressure-sensitive adhesive sheet that is rolled up, or as a sheet-shaped optical film with a pressure-sensitive adhesive sheet.

[0125] The optical film with adhesive sheet of this embodiment is typically used in an image display device. The image display device can be formed, for example, by bonding the optical film with adhesive sheet 20A or 20B to an image display panel. The bonding is performed, for example, by an adhesive sheet 1. The image display device may be an organic EL display or a liquid crystal display. However, the image display device is not limited to the above examples. The image display device may be an electroluminescence (EL) display, a plasma display (PD), a field emission display (FED: Field Emission Display), or the like. The image display device can be used for home appliances, in-vehicle applications, public information displays (PID), and the like. EXAMPLES

[0126] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the examples shown below.

[0127] [Preparation of release liner A] Addition reaction curing type silicone (LTC761 containing hexenyl group-containing polyorganosiloxane, 30 wt% toluene solution, manufactured by Dow Corning Toray) 30 parts by weight, release control agent (BY24-850 containing unreactive silicone resin, manufactured by Dow Corning Toray) 0.9 parts by weight, and curing catalyst (SRX212 containing platinum catalyst, manufactured by Dow Corning Toray) 2 parts by weight, and toluene / hexane mixed solvent (volume ratio 1: 1) as a dilution solvent were mixed to obtain a silicone-based release agent composition A. The concentration of silicone solids in the release agent composition A was 1.0 wt%. Next, the release agent composition A was applied to one side of a liner substrate (Lumirror XD500P, a polyester film, thickness 75 μm) with a wire bar and heated at 130 ° C for 1 minute to prepare a release liner A having a release layer (thickness 120 nm) on one side.

[0128] Example 1 [Preparation of Adhesive Composition] The mixture consisted of 95.1 parts by weight of n-butyl acrylate (BA), 4.8 parts by weight of acrylic acid (AA), and 0.1 parts by weight of 4-hydroxybutyl acrylate (HBA), and 2,2-dimethoxy-1,2-diphenylethan-1-one (Omnirad 651, IGM Resins BV) 0.05 parts by weight, and bis(2,4,6-trimethylbenzoyl ) Phenylphosphine oxide (Omnirad819, IGM Resins BV) 0.0 The monomer syrup was charged into a four-bottom flask and irradiated with ultraviolet light under a nitrogen atmosphere to obtain a partially photopolymerized monomer syrup. The ultraviolet light was irradiated until the viscosity of the liquid in the flask (measurement conditions: BH viscometer No. 5 rotor, 10 rpm, measurement temperature 30°C) reached about 20 Pa·s. Next, 0.09 parts by weight of 1,9-nonanediol diacrylate (NDDA) as a crosslinking agent and 0.3 parts by weight of isooctyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (BASF's "Irganox 1135") as an antioxidant were added to 100 parts by weight of the monomer syrup and mixed uniformly to obtain a pressure-sensitive adhesive composition of Example 1.

[0129] [Evaluation of peel strength PS0] The pressure-sensitive adhesive composition of Example 1 was applied to one side of a base sheet (Lumirror XD500P, a polyester film with no release layer, thickness 75 μm) using an applicator to form a coating layer (thickness 20 μm). Next, release liner A was placed on the formed coating layer to obtain a first laminate. Release liner A was placed so that the release layer was in contact with the coating layer. Next, a light source with an illuminance of 2.42 mW / cm was applied from the side of the base sheet in the first laminate. 2 , Irradiation time 1 The coating layer was photocured by irradiating it with ultraviolet light (black light source) under the condition of 10 minutes, thereby forming a second laminate composed of the base sheet, the adhesive sheet (thickness 20 μm) and the release liner A.

[0130] A test piece having a length of 220 mm and a width of 50 mm (the length direction is the coating direction of the pressure-sensitive adhesive composition) was cut out from the formed second laminate. A 180° peel test was performed on the test piece using a tensile tester to peel only the release liner A in the length direction, and the peel strength PS0 was evaluated. The peel test conditions were as described above.

[0131] [Evaluation of peel strength PS1] A second laminate was prepared using the same method as in the evaluation of the peel strength PS0 above, and the adhesive sheet was peeled off. Then, the release liner A was peeled off. Next, using the peeled release liner A, the formation of the first laminate, the formation of the second laminate by irradiation with ultraviolet light, the cutting out of the test piece, and the evaluation of the release force were carried out in the same manner as above. In this way, the release force PS1 was evaluated.

[0132] (Examples 2 to 4) Except for using the compounds shown in Table 1 as antioxidants, pressure-sensitive adhesive compositions of Examples 2 to 4 were obtained in the same manner as in Example 1. The peel strengths PS0 and PS1 of these pressure-sensitive adhesive compositions were evaluated in the same manner as in Example 1.

[0133] Comparative Example 1 Except for not using the antioxidant, a pressure-sensitive adhesive composition of Comparative Example 1 was obtained by the same method as in Example 1. For this pressure-sensitive adhesive composition, the peel strengths PS0 and PS1 were evaluated by the same method as in Example 1.

[0134] [Table 1]

[0135] The abbreviations in Table 1 are as follows. Irg1135: Isooctyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (BASF "Irganox 1135", molecular weight 390) Irg1010: Pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (BASF "Irganox 1010", molecular weight 1178) LA-52: Tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylate (ADEKA "ADEKA STAB LA-52", molecular weight 847) 2112: Tris(2,4-di-t-butylphenyl)phosphite (ADEKA "ADEKA STAB 2112", molecular weight 647)

[0136] As can be seen from Table 1, the adhesive compositions of the Examples had a peel strength PS1 of 1.0 N / 50 mm or less as determined by the above test. Even if the release liner is repeatedly used during production, there is a tendency for the increase in the peel strength of the release liner with respect to the PSA sheet to be suppressed, which reduces the amount of release liner that is discarded and enables the production of PSA sheets with low environmental impact.

[0137] (Reference example 1) [Preparation of release liner B] Release liner B having a release layer (thickness 60 nm) on one side was prepared using the same method as the release liner A described above, except that the thickness of the release agent composition A applied to the liner substrate was changed.

[0138] The release forces PS0 and PS1 were evaluated in the same manner as in Example 1, except that the release liner B was used.

[0139] (Reference examples 2~4) The peel strengths PS0 and PS1 were evaluated in the same manner as in Example 1, except that the ultraviolet irradiation conditions were changed as shown in Table 2.

[0140] [Table 2]

[0141] As can be seen from Table 2, the adhesive composition of this embodiment was subjected to a test to determine the peel strength PS1. Even when the experimental conditions (the thickness of the release layer in the release liner and the ultraviolet irradiation conditions) were changed, the peel force PS1 was maintained at a small value. [Industrial Applicability]

[0142] The pressure-sensitive adhesive composition of the present invention can be used, for example, in optical laminates and image display devices. [Explanation of symbols]

[0143] 1 Adhesive sheet 2. Optical Film 10 (First) Laminate 11 Base sheet 12 Coating layer 13 Release Liner 20A, 20B Optical film with adhesive sheet

Claims

1. A photocurable pressure-sensitive adhesive composition comprising a monomer group including a (meth)acrylic monomer and / or a partial polymer of the monomer group, and a photopolymerization initiator, The pressure-sensitive adhesive composition further comprises an antioxidant, Peel strength PS obtained by the following test 1 The pressure-sensitive adhesive composition has a compressive strength of 1.0 N / 50 mm or less. Test: A laminate including, in this order, a base sheet, a coating layer including the pressure-sensitive adhesive composition, and a release liner having a release layer with a thickness of 120 nm was subjected to an illuminance of 2.42 mW / cm 2 , irradiation time 10 The adhesive sheet is formed from the coating layer by irradiating the coating layer with ultraviolet light for 10 minutes, and the release liner is peeled off from the adhesive sheet in step A. Step A and step B are performed repeatedly using the release liner peeled off in step B to reuse the release liner. The peel strength PS between the reused release liner obtained in step B, which has been peeled off once from the adhesive sheet counting from an unused state, and the adhesive sheet obtained in step A by repeated execution is 1 Identify.

2. The peeling force P.S. 1 The pressure-sensitive adhesive composition according to claim 1, wherein the compressive strength is 0.5 N / 50 mm or less.

3. Peel strength PS between the release liner and the pressure-sensitive adhesive sheet in an unused state 0 is 0.01N / The pressure-sensitive adhesive composition according to claim 1 , which has a thickness of 50 mm or more.

4. The pressure-sensitive adhesive composition according to claim 1 , wherein the antioxidant comprises at least one selected from the group consisting of hindered phenol compounds and hindered amine compounds.

5. The pressure-sensitive adhesive composition according to claim 1 , wherein the antioxidant has a molecular weight of 1,500 or less.

6. The pressure-sensitive adhesive composition according to claim 1 , wherein the monomer group includes a carboxyl group-containing monomer.

7. The pressure-sensitive adhesive composition according to claim 1 , wherein the solvent content is 5% by weight or less.

8. A pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition according to any one of claims 1 to 7.

9. The pressure-sensitive adhesive sheet according to claim 8, having a thickness of 5 to 40 μm.

10. The pressure-sensitive adhesive sheet according to claim 8 ; An optical film; The optical film with adhesive sheet is provided.

11. The optical film with a pressure-sensitive adhesive sheet according to claim 10 , wherein the optical film is a film including at least one selected from the group consisting of a polarizing film and a retardation film.

12. A step A of irradiating a laminate including, in this order, a base sheet, a coating layer including the pressure-sensitive adhesive composition according to any one of claims 1 to 7, and a release liner with light to form a pressure-sensitive adhesive sheet from the coating layer; Step B of peeling the release liner from the pressure-sensitive adhesive sheet; Including, A method for producing a pressure-sensitive adhesive sheet, comprising repeatedly carrying out steps A and B using the release liner peeled off in step B, thereby reusing the release liner.

13. A method for producing an optical film with a pressure-sensitive adhesive sheet, comprising laminating the pressure-sensitive adhesive sheet formed by the method for producing the optical film with a pressure-sensitive adhesive sheet according to claim 12 and an optical film to form an optical film with a pressure-sensitive adhesive sheet. Manufacturing method.

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