TW202039232A - Optical layered film having adhesive layer and image display device - Google Patents

Abstract

This optical layered film having an adhesive layer includes a protective film, an optical film, an adhesive layer, and a separator layered in the given order, wherein: the optical film has a thickness of 80[mu]m or less; the protective film has a thickness of 30[mu]m or more; and the protective film has a tensile modulus of elasticity of 1GPa or more. According to this optical layered film having an adhesive layer, the degree of dents that may occur at the time of storing can be controlled.

Description

Optical laminated film with adhesive layer and image display device

The invention relates to an optical laminated film with an adhesive layer and an image display device.

Various thin image display devices such as liquid crystal displays and organic EL displays generally have a laminated structure including image forming layers such as a liquid crystal layer and an organic EL light emitting layer, and one or more optical films. The bonding of the layers constituting the image display device generally uses an adhesive layer, and a method of manufacturing an image display device by adhering an optical film with an adhesive layer provided with an adhesive layer on at least one side to the image forming layer is widely used (refer to the patent Literature 1). And when supplying optical films with adhesive layers, they are sometimes supplied in the form of optical laminate films with adhesive layers that are further equipped with a separator for protecting the adhesive layer and/or a protective film for protecting the optical film. . In addition, the separator may be peeled off when the optical laminated film is used, for example, when it is adhered to the image forming layer.

Prior art literature Patent literature Patent Document 1: Japanese Patent Laid-Open No. 2018-28573

Problems to be solved by the invention The optical laminated film with the adhesive layer is usually stored in the state of being wound into a roll or in the state of being laminated in sheets before being combined with the image forming layer to manufacture the image display device. However, it has been discovered through research by the inventors that the above-mentioned storage has a tendency to generate minute dents in the adhesive layer, and when a thinned optical film is provided, this tendency is enhanced. The dent may become an optical defect. Moreover, after the image display device is manufactured, the same dent may also be generated during the storage of the device. In Patent Document 1, these points are not considered.

The object of the present invention is to provide an optical laminated film with an adhesive layer that can suppress the dents that may occur during storage.

Means to solve the problem The present invention provides an optical laminated film with an adhesive layer, which is laminated with a protective film, an optical film, an adhesive layer and a separator in sequence; Wherein, the thickness of the aforementioned optical film is 80μm or less, The thickness of the protective film is 30 μm or more, and the tensile modulus of the protective film is 1 GPa or more.

In another aspect, the present invention provides an image display device, It is provided with the above-mentioned part of the optical laminated film with an adhesive layer of the present invention except for the aforementioned separator.

Invention effect In the optical laminate film with an adhesive layer of the present invention, although a thinned optical film with a thickness of 80μm or less is provided, by setting both the thickness of the protective film and the tensile modulus of elasticity to a predetermined value or more, it can be dispersed The pressure generated by the entrapment of foreign objects can suppress the progress of dents that may be generated in the adhesive layer caused by the entrapment of foreign objects. Therefore, in the optical laminated film with an adhesive layer of the present invention, the degree of dents that may be generated during storage can be suppressed.

The following describes the embodiments of the present invention with reference to the drawings. The present invention is not limited by the embodiments shown below.

An example of the optical laminated film with adhesive layer of the present invention is shown in FIG. 1. The optical laminated film 1 with an adhesive layer in FIG. 1 includes a protective film 2, an optical film 3, an adhesive layer 4, and a separator 5. And the protective film 2, the optical film 3, the adhesive layer 4 and the separator 5 are laminated in sequence. The thickness of the optical film 3 is 80 μm or less. The thickness of the protective film 2 is 30 μm or more. In addition, the tensile modulus of elasticity of the protective film 2 is 1 GPa or more. In addition, the tensile elastic modulus of the protective film 2 is a value at normal temperature (23°C).

[Optical Film] The optical film 3 is, for example, a polarizing film or a retardation film. The optical film 3 may also be a laminated film or an optical laminated body including a polarizing film and/or a retardation film. However, the optical film 3 is not limited to the above examples. The optical film 3 may include a glass film.

The thickness of the optical film 3 is 80 μm or less. According to the study by the inventors, when the optical laminate film 1 has a thinned optical film 3 having a thickness of 80 μm or less, the degree of dents in the adhesive layer 4 that may occur during storage tends to increase. However, in the optical laminated film 1, even if the thinned optical film 3 is provided, the degree of dents in the adhesive layer 4 that may be generated during storage can be suppressed. The thickness of the optical film 3 may be 70 μm or less, 60 μm or less, 50 μm or less, 40 μm or less, and more preferably 35 μm or less. The lower limit of the thickness of the optical film 3 is, for example, 1 μm or more.

The polarizing film includes a polarizing member. A polarizer protective film may also be bonded to at least one surface of the polarizer. Any adhesive or bonding agent can be used for joining the polarizer and the polarizer protective film. The polarizer is typically a polyvinyl alcohol (PVA) film in which iodine has been oriented by stretching in the air (dry stretching), boric acid water stretching, or the like.

The retardation film is a film having birefringence in the in-plane direction and/or the thickness direction. The retardation film is, for example, a film obtained by aligning and fixing a stretched resin film and a liquid crystal material.

The retardation film is, for example, a λ/4 plate, a λ/2 plate, an anti-reflection retardation film (for example, refer to paragraphs 0221, 0222, 0228 of Japanese Patent Laid-Open No. 2012-133303), and a retardation film for viewing angle compensation ( For example, refer to paragraphs 0225 and 0226 of Japanese Patent Laid-Open No. 2012-133303) and oblique orientation retardation films for viewing angle compensation (for example, refer to paragraph 0227 of Japanese Patent Laid-Open No. 2012-13303). However, as long as the retardation film has birefringence in the in-plane direction and/or the thickness direction, it is not limited to the above examples. There are also no restrictions on the retardation value, arrangement angle, three-dimensional birefringence, single-layer or multi-layer etc. of the retardation film. As the retardation film, a well-known film can be used.

The thickness of the retardation film is, for example, 50 μm or less.

The optical film 3 may be a single-layer film, or a multilayer film composed of two or more layers.

[Protective Film] The protective film 2 has a function of protecting the optical film 2 during the circulation and storage of the optical laminated film 1 and when the optical laminated film 1 is installed in an image display device. When the protective film 2 is installed in the image display device, it can also be a film that functions as a window to the external space. The protective film 2 is typically a resin film. The resin constituting the protective film 2 is, for example, polyester such as polyethylene terephthalate (PET), polyolefin such as polyethylene and polypropylene, acrylic acid, cycloolefin, polyimide, polyamide, and polyester Better. In other words, the protective film 2 may also be a polyester film. However, the protective film 2 is not limited to the above examples. The protective film may be a glass film, or may be a laminated film including a glass film. The protective film 2 can also be treated with anti-glare, anti-reflection, anti-static and other surface treatments.

The thickness of the protective film 2 is 30 μm or more. The thickness of the protective film 2 is 35 μm or more, 40 μm or more, 45 μm or more, and more preferably 50 μm or more. The upper limit of the thickness of the protective film 2 is, for example, 100 μm or less.

The tensile modulus of elasticity of the protective film 2 is 1 GPa or more. The tensile modulus of elasticity of the protective film 2 may also be 2 GPa or more, 3 GPa or more, and more preferably 4 GPa or more. The upper limit of the tensile modulus of the protective film 2 is, for example, 100 GPa or less.

The protective film 2 may be bonded to the optical film 3 by any adhesive layer. The adhesive layer joining the protective film 2 and the optical film 3 may also have the structure described in the description of the adhesive layer 4 below.

[Adhesive layer] The adhesive layer 4 can be made of, for example, acrylic adhesives, rubber adhesives, vinyl alkyl ether adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, etc. Various adhesive compositions including adhesives, fluorine-based adhesives, epoxy-based adhesives, and polyether-based adhesives. From the viewpoint of excellent various characteristics such as optical transparency, processability, durability, and adhesion, the adhesive layer 4 is preferably composed of an acrylic adhesive composition containing a (meth)acrylic polymer. In addition, in this specification, "(meth)acrylic acid" means acrylic acid and methacrylic acid. In addition, "(meth)acrylate" means acrylate and methacrylate.

The type of the adhesive composition constituting the adhesive layer 4 may be, for example, an emulsion type, a solvent type (solution type), an active energy ray hardening type, a hot melt type (hot melt type), and the like. Among them, a solvent-based or active energy-ray-curable adhesive composition is preferred. From the viewpoints of productivity and easy formation of a thick adhesive layer 4, the active-energy-ray-curable adhesive composition Appropriate. However, the type of adhesive composition is not limited by the above examples.

The acrylic adhesive composition that can constitute the adhesive layer 4 is explained below.

[(Meth) acrylic polymer] The (meth)acrylic polymer preferably has, as a main unit, a structural unit derived from a (meth)acrylic monomer (A) having an alkyl group with 1 to 30 carbon atoms in the side chain. The alkyl group may be linear or branched. The (meth)acrylic polymer may have one or more structural units derived from the (meth)acrylic monomer (A). The (meth)acrylic monomer (A) is, for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, second butyl (meth)acrylate, ( Tertiary butyl meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isoamyl (meth)acrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate Ester, isoheptyl (meth)acrylate, 2-ethylhexyl (meth)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), (meth) ) N-tridecyl acrylate, n-tetradecyl (meth)acrylate. In addition, the "main unit" in this specification means, for example, a unit that occupies 50% by mass or more of the total structural units of the polymer, preferably a unit that occupies 80% by mass or more, and more preferably 90% by mass. The above units are more preferably units that account for more than 94% by mass.

The (meth)acrylic polymer may have a structural unit derived from a (meth)acrylic monomer (A) having a long-chain alkyl group in the side chain. This structural unit is, for example, n-dodecyl (meth)acrylate (lauryl (meth)acrylate). In addition, in this specification, the "long-chain alkyl group" means an alkyl group with 6 to 30 carbon atoms.

When the (meth)acrylic polymer is a homopolymer, it may also have a structural unit derived from the (meth)acrylic monomer (A) with a glass transition temperature (Tg) in the range of -70~-20℃ . The structural unit is, for example, 2-ethylhexyl acrylate.

The (meth)acrylic polymer may have structural units other than those derived from the (meth)acrylic monomer (A). This structural unit is derived from the monomer (B) copolymerizable with the (meth)acrylic monomer (A). The (meth)acrylic polymer may have one or two or more of these structural units.

The monomer (B) is, for example, a (meth)acrylic monomer (C) having a hydroxyl group. The (meth)acrylic monomer (C) is, for example, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, (Meth) 6-hydroxyhexyl acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, etc. Hydroxyalkyl meth)acrylate, or (4-hydroxymethylcyclohexyl)methyl acrylate, etc. From the viewpoint of improving the durability and adhesion of the adhesive layer 4, the (meth)acrylic monomer (C) is preferably 2-hydroxyethyl (meth)acrylate or 4-(meth)acrylic acid. Hydroxybutyl ester.

The monomer (B) may also be a carboxyl group-containing monomer, an amine group-containing monomer, or an amine group-containing monomer. By using these monomers (B), the adhesion of the adhesive layer 4 can be improved. The carboxyl group-containing monomer is, for example, (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and the like. The amine group-containing monomer is, for example, N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, and the like. The amine group-containing monomers are, for example: (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-iso Propyl acrylamide, N-methyl (meth) acrylamide, N-butyl (meth) acrylamide, N-hexyl (meth) acrylamide, N-methylol (methyl) Acrylamide, N-hydroxymethyl-N-propane (meth)acrylamide, aminomethyl (meth)acrylamide, aminoethyl (meth)acrylamide, mercaptomethyl (meth) Acrylic amine monomers such as acrylamide and mercaptoethyl (meth)acrylamide; N-(meth)acryloyl mopholin, N-(meth)acryloyl piperidine, N-( (Meth)acryloylpyrrolidine and other N-acryloyl heterocyclic monomers; N-vinylpyrrolidone, N-vinyl-ε-caprolactam and other N-vinyl lactam-containing monomers Wait.

The monomer (B) may also be a polyfunctional monomer. By using a multifunctional monomer, the gel fraction of the adhesive layer 4 can be adjusted or the cohesive force can be controlled. Multifunctional monomers are, for example, hexanediol di(meth)acrylate (1,6-hexanediol di(meth)acrylate), butanediol di(meth)acrylate, (poly)ethylene Glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, neopentyl erythritol di(meth)acrylate, neopentyl erythritol Tri(meth)acrylate, dineopentol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, (meth) Multifunctional acrylates such as allyl acrylate, vinyl (meth)acrylate, epoxy acrylate, polyester acrylate, and urethane acrylate; and divinylbenzene. The multifunctional acrylates are preferably 1,6-hexanediol diacrylate and dineopentaerythritol hexa(meth)acrylate.

Other monomers (B) other than the above are, for example: 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, ( (Meth) 3-methoxypropyl acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, 4-ethoxybutyl (meth)acrylate, etc. ) Alkoxyalkyl acrylate; epoxy group-containing monomers such as glycidyl (meth)acrylate and methylglycidyl (meth)acrylate; sulfonic acid group-containing monomers such as sodium vinyl sulfonate ; Phosphoric acid group-containing monomers; (meth)acrylates with alicyclic hydrocarbon groups such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, etc.; (meth) ) (Meth)acrylates with aromatic hydrocarbon groups such as phenyl acrylate, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate; vinyl esters such as vinyl acetate and vinyl propionate; styrene , Aromatic vinyl compounds such as vinyl toluene; olefins or dienes such as ethylene, propylene, butadiene, isoprene, isobutylene, etc.; vinyl ethers such as vinyl alkyl ethers; vinyl chloride.

The (meth)acrylic polymer is derived from (meth)acrylic monomers (C) having hydroxyl groups, carboxyl group-containing monomers, amine group-containing monomers, amide group-containing monomers, and multifunctional monomers The total content of the constituent units should be 20% by mass or less, more preferably 10% by mass or less, more preferably 8% by mass or less, and particularly preferably 5% by mass or less. When the (meth)acrylic polymer has the structural unit, the total content of the structural unit is, for example, 0.01% by mass or more, or 0.05% by mass or more.

The total content of constituent units derived from other monomers (B) in the (meth)acrylic polymer is, for example, 30% by mass or less, or 10% by mass or less, and preferably 0% by mass (not including the constituent unit).

The (meth)acrylic polymer can be formed by polymerizing one or more of the above-mentioned monomers by a known method. The monomer can also be polymerized with a partial polymer of the monomer. The polymerization can be carried out by, for example, solution polymerization, emulsion polymerization, bulk polymerization, thermal polymerization, or active energy ray polymerization. From the viewpoint that the adhesive layer 4 having excellent optical transparency can be formed, solution polymerization and active energy ray polymerization are preferable. The polymerization should be carried out without contacting the monomer and/or part of the polymer with oxygen. Therefore, polymerization in an inert gas atmosphere such as nitrogen or polymerization in a state where oxygen is blocked by a resin film can be used. The formed (meth)acrylic polymer can be any type of random copolymer, block copolymer, graft copolymer and the like.

The polymerization system forming the (meth)acrylic polymer may include one or more polymerization initiators. The type of polymerization initiator can be selected according to the polymerization reaction, and for example, it can be a photopolymerization initiator or a thermal polymerization initiator.

Solvents used in solution polymerization are, for example, esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; cyclohexane and methylcyclohexane Alicyclic hydrocarbons such as alkanes; ketones such as methyl ethyl ketone and methyl isobutyl ketone. However, the solvent is not limited to the above examples. The solvent may also be a mixed solvent of two or more solvents.

The polymerization initiator used for solution polymerization is, for example, an azo-based polymerization initiator, a peroxide-based polymerization initiator, and an oxygen-reduced polymerization initiator. The peroxide-based polymerization initiator is, for example, dibenzoyl peroxide and t-butyl permaleate. Among them, the azo polymerization initiator disclosed in Japanese Patent Laid-Open No. 2002-69411 is suitable. This azo polymerization initiator is, for example, 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2 -Methylpropionic acid) dimethyl ester, 4,4'-azobis-4-cyanovaleric acid. However, the polymerization initiator is not limited to the above examples. The amount of the azo polymerization initiator used is, for example, 0.05 to 0.5 parts by weight relative to 100 parts by weight of the total amount of monomers, or 0.1 to 0.3 parts by weight.

The active energy rays used for the polymerization of active energy rays are, for example, ionizing radiation such as alpha rays, beta rays, gamma rays, neutron rays, and electron rays, and ultraviolet rays. The active energy rays are preferably ultraviolet rays. Polymerization using ultraviolet radiation is also called photopolymerization. The polymerization system of active energy ray polymerization typically contains a photopolymerization initiator. The polymerization conditions of the living energy polymerization are not limited as long as the (meth)acrylic polymer can be formed.

系光聚合引發劑。惟，光聚合引發劑不受上述例限定。The photopolymerization initiators are, for example, benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, and photoactive oximes Photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, 9-oxysulfur

Department of photopolymerization initiator. However, the photopolymerization initiator is not limited to the above examples.

系光聚合引發劑例如為：9-氧硫

、2-氯9-氧硫

、2-甲基9-氧硫

、2,4-二甲基9-氧硫

、異丙基9-氧硫

、2,4-二異丙基9-氧硫

、十二烷基9-氧硫

。Benzoin ether-based photopolymerization initiators are, for example, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy -1,2-Diphenylethyl-1-one, anisole methyl ether. The acetophenone-based photopolymerization initiator is, for example, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4 -Phenoxydichloroacetophenone, 4-(tert-butyl)dichloroacetophenone. The α-ketol-based photopolymerization initiator is, for example, 2-methyl-2-hydroxypropiophenone and 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one. The aromatic sulfonyl chloride-based photopolymerization initiator is, for example, 2-naphthalenesulfonyl chloride. The photoactive oxime-based photopolymerization initiator is, for example, 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime. The benzoin-based photopolymerization initiator is, for example, benzoin. The benzyl-based photopolymerization initiator is, for example, benzyl. The benzophenone-based photopolymerization initiator is, for example, benzophenone, benzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinyl benzophenone, α-Hydroxycyclohexyl phenyl ketone. The ketal-based photopolymerization initiator is, for example, benzyl dimethyl ketal. 9-oxysulfur

The photopolymerization initiator is for example: 9-oxysulfur

, 2-Chloro 9-oxysulfur

, 2-Methyl 9-oxysulfur

, 2,4-Dimethyl 9-oxysulfur

, Isopropyl 9-oxysulfur

, 2,4-Diisopropyl 9-oxysulfur

, Dodecyl 9-oxysulfur

.

The amount of the photopolymerization initiator used is, for example, 0.01 to 1 part by weight, or 0.05 to 0.5 part by weight, relative to 100 parts by weight of the total amount of monomers.

In addition, the multifunctional monomer (multifunctional acrylate, etc.) of the monomer (B) can also be used in any type of adhesive composition of solvent type and active energy ray hardening type. When using both a polyfunctional monomer and a photopolymerization initiator, for example, after removing the solvent by thermal drying, the adhesive composition can be cured by irradiating active energy rays.

The weight average molecular weight (Mw) of the (meth)acrylic polymer is, for example, 1 million to 2.5 million. From the viewpoint of durability and heat resistance of the adhesive layer 4, it is preferably 1.2 million to 2 million, and more preferably 1.4 million to 1.8 million. In addition, the weight average molecular weight (Mw) of polymers and oligomers in this specification is a value (in terms of polystyrene) measured by GPC (Gel Permeation Chromatography).

The content of the (meth)acrylic polymer in the acrylic adhesive composition is, in terms of solid content ratio, for example, 50% by mass or more, 60% by mass or more, or 70% by mass or more.

[(Meth) acrylic oligomer] The acrylic adhesive composition may further contain a (meth)acrylic oligomer. By containing the (meth)acrylic oligomer, the molecular chains of the (meth)acrylic polymer can be entangled with each other, and the stress relaxation of the adhesive layer 4 can be improved.

The (meth)acrylic oligomer may have the same composition as the above-mentioned (meth)acrylic polymer except that the weight average molecular weight (Mw) is different. The weight average molecular weight (Mw) of the (meth)acrylic oligomer is, for example, 1000 or more, or 2000 or more, 3000 or more, and more preferably 4000 or more. The upper limit of the weight average molecular weight (Mw) of the (meth)acrylic oligomer is, for example, 30,000 or less, and may be 15,000 or less, 10,000 or less, and more preferably 7,000 or less. The (meth)acrylic oligomer having a weight average molecular weight (Mw) in these ranges can further improve the stress relaxation properties of the adhesive layer 4.

The (meth)acrylic oligomer has, for example, one or more structural units derived from the following monomers: methyl (meth)acrylate, ethyl (meth)acrylate, and propyl (meth)acrylate , Isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, second butyl (meth)acrylate, third butyl (meth)acrylate, (meth) ) Amyl acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, Isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate Alkyl esters, dodecyl (meth)acrylate and other alkyl (meth)acrylates; cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentyl (meth)acrylate, etc. (Meth) acrylic acid and alicyclic alcohol ester; (meth) phenyl acrylate, benzyl (meth) acrylate and other (meth) aryl acrylates; (former)基)acrylate.

The (meth)acrylic oligomer preferably has a structural unit derived from an acrylic monomer having a relatively bulky structure. In this case, the adhesiveness of the adhesive layer 4 can be further improved. The acrylic monomer is, for example: (meth)acrylic acid isobutyl (meth)acrylate, (meth)acrylic acid tert-butyl (meth)acrylate and other branched alkyl (meth)acrylate alkyl esters; (meth)acrylic acid Cyclohexyl ester, isobornyl (meth)acrylate, dicyclopentyl (meth)acrylate, etc. (meth)acrylic acid and alicyclic alcohol esters; phenyl (meth)acrylate, benzyl (meth)acrylate Esters and other (meth)acrylate aryl esters. The acrylic monomer preferably has a cyclic structure, and more preferably has 2 or more cyclic structures. In addition, when the (meth)acrylic oligomer is polymerized, and/or is irradiated with ultraviolet light when the adhesive layer 4 is formed, the acrylic monomer should preferably not have unsaturated bonds, because it is unlikely to hinder the polymerization and/or Or the formation can be performed, for example, an alkyl (meth)acrylate having a branched structure and an alkyl (meth)acrylate, an ester of (meth)acrylic acid and alicyclic alcohol can be used.

Specific examples of (meth)acrylic oligomers are: copolymer of butyl acrylate and methyl acrylate and acrylic acid, copolymer of cyclohexyl methacrylate and isobutyl methacrylate, cyclohexyl methacrylate Copolymer with isobornyl methacrylate, copolymer of cyclohexyl methacrylate and methacrylate, copolymer of cyclohexyl methacrylate and diethyl acrylamide, 1-adamantyl acrylate Copolymer with methyl methacrylate, copolymer of dicyclopentyl methacrylate and isobornyl methacrylate, selected from dicyclopentyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate Copolymer of at least one of acrylate, isobornyl acrylate and cyclopentyl methacrylate with methyl methacrylate, homopolymer of dicyclopentyl acrylate, homopolymer of 1-adamantyl methacrylate , Homopolymer of 1-adamantyl acrylate.

The polymerization method of the (meth)acrylic oligomer can be the above-mentioned polymerization method of the (meth)acrylic polymer.

When the adhesive composition contains a (meth)acrylic oligomer, the blending amount is, for example, 70 parts by weight or less, or 50 parts by weight or less, relative to 100 parts by weight of the (meth)acrylic polymer. It may be 40 parts by weight or less. The lower limit of the blending amount relative to 100 parts by weight of the (meth)acrylic polymer is, for example, 1 part by weight or more, or 2 parts by weight or more, and more preferably 3 parts by weight or more.

The (meth)acrylic oligomer can also be used in adhesive compositions of either solvent type or active energy ray hardening type. However, when the active energy ray-curable adhesive composition is used and the (meth)acrylic oligomer has been dissolved in a solvent, the mixture with the (meth)acrylic oligomer can be heated, for example, After drying and removing the solvent, curing can proceed by irradiation with active energy rays.

[Crosslinking agent] The acrylic adhesive composition may further contain a crosslinking agent. By using a crosslinking agent, the cohesive force of the adhesive layer 4 can be improved.

The crosslinking agent is, for example, an organic crosslinking agent and a polyfunctional metal chelate compound. The organic crosslinking agent is, for example, an isocyanate-based crosslinking agent, a peroxide-based crosslinking agent, an epoxy-based crosslinking agent, and an imine-based crosslinking agent. The multifunctional metal chelate has a structure in which a multivalent metal and an organic compound are covalently bonded or coordinately bonded. The polyvalent metal is, for example, Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, Ti. The atom in an organic compound in which a polyvalent metal can be covalently bonded or coordinately bonded is typically an oxygen atom. Examples of organic compounds include alkyl esters, alcohol compounds, carboxylic acid compounds, ether compounds, and ketone compounds. In addition, organic crosslinking agents and multifunctional metal chelate compounds can also be used in adhesive compositions of either solvent type or active energy ray hardening type.

When the adhesive composition is solvent-based, the cross-linking agent is preferably a peroxide-based cross-linking agent, an isocyanate-based cross-linking agent, and more preferably a peroxide-based cross-linking agent. In addition, since the peroxide-based crosslinking agent is used to crosslink between the side chains of the (meth)acrylic polymer, the peroxide-based crosslinking agent is used instead of the crosslinking with the isocyanate-based crosslinking agent. For cross-linking, the degree of freedom of the molecular chain after cross-linking will become higher. Therefore, the cohesive force of the adhesive layer 4 can be increased, and at the same time, the stress relaxation properties can be ensured more reliably. On the other hand, compared with the crosslinking with the peroxide-based crosslinking agent, the crosslinking with the isocyanate-based crosslinking agent can improve the durability of the adhesive layer 4. However, cross-linking with a bifunctional isocyanate cross-linking agent will form a two-dimensional cross-linked structure, so although it is not as good as the cross-linking with a peroxide-based cross-linking agent, it can still more reliably ensure the adhesive layer 4 Stress relaxation. When an isocyanate-based crosslinking agent is used, a trifunctional crosslinking agent that forms a strong three-dimensional crosslinking structure and the above-mentioned difunctional crosslinking agent can also be used in combination to improve the balance between durability and stress relaxation. In addition, in order to further improve this balance, a peroxide-based crosslinking agent and an isocyanate-based crosslinking agent may be used in combination. In addition, the polyfunctional monomer of the above-mentioned monomer (B) and a crosslinking agent may be used in combination.

When the adhesive composition contains a crosslinking agent, the blending amount is, for example, 0.1 to 10 parts by weight, or 0.2 to 5 parts by weight, or even 0.3 to 100 parts by weight of the (meth)acrylic polymer. 3 parts by weight.

When the peroxide-based crosslinking agent is used alone, the blending amount is, for example, 0.2 to 5 parts by weight, or 1 to 3 parts by weight relative to 100 parts by weight of the (meth)acrylic polymer.

When a peroxide-based crosslinking agent and an isocyanate-based crosslinking agent are used in combination, the weight ratio of the peroxide-based crosslinking agent to the isocyanate-based crosslinking agent is preferably 1.2 or more, more preferably 1.5 or more, and more preferably 3 or more. In addition, the upper limit of the weight ratio is, for example, 500 or less, may also be 300 or less, and may even be 200 or less.

[additive] The acrylic adhesive composition may also contain other additives. Examples of additives include: silane coupling agents, polyether compounds (polyalkylene glycol represented by polypropylene glycol, etc.), colorants such as pigments and dyes, surfactants, plasticizers, tackifiers, surface lubricants, Levelers, softeners, antioxidants, anti-aging agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors, antistatic agents (alkali metal salts of ionic compounds, ionic liquids, ionic solids, etc.), inorganic fillers, Organic fillers, metal powders and other powders, particles, and foils.

[Formation of Adhesive Layer 4] The adhesive layer 4 composed of an acrylic adhesive composition can be formed as follows. When the adhesive composition is solvent-based, for example, a mixture of (meth)acrylic polymer and solvent and optionally (meth)acrylic oligomer, crosslinking agent, additives, etc. can be applied to the base film And dry it to form the adhesive layer 4. When the adhesive composition is an active energy ray-curable type, for example, it can be polymerized to become a monomer (group) of the (meth)acrylic polymer and a partial polymer of the monomer (group) as needed, and a polymerization initiator A mixture of (meth)acrylic oligomers, crosslinking agents, additives, solvents, etc. is coated on the substrate film, and the solvent is removed by drying as needed, and then irradiated with active energy rays to form the adhesive layer 4. The substrate film may also be a film whose surface has been peeled off. The adhesive layer 4 formed on the base film can be transferred to any layer. Furthermore, the base film may also be an optical film. In this case, by further disposing the protective film 2 and the separator 5, an adhesive layer-attached optical laminate film with the adhesive layer 4 can be obtained. In addition, the base film may also be the separator 5. In this case, by further disposing the optical film 3 and the protective film 2, an adhesive layer-attached optical laminated film with the adhesive layer 4 can be obtained.

A well-known method can be used to coat the above-mentioned mixture on the base film. Coating can be performed, for example, by roll coating, touch roll coating, gravure coating, reverse coating, roll brushing, spray cloth, dip roll coating, bar coating, knife coating, air knife coating, curtain coating Coating, lip coating, and extrusion coating using a die coater etc. are implemented.

The mixture coated on the substrate film should have a viscosity suitable for handling and coating. Therefore, when the adhesive composition is an active energy ray hardening type, the mixture should preferably include a part of the polymer of the monomer (group).

The release film that can be used for the base film is, for example, a resin film that has been subjected to surface release treatment with polysiloxane.

The drying temperature of the mixture is, for example, 40 to 200°C, may also be 50 to 180°C, or even 70 to 170°C. The drying time of the mixture is, for example, 5 seconds to 20 minutes, may also be 5 seconds to 10 minutes, or even 10 seconds to 5 minutes.

When the adhesive layer 4 has a thickness of 25 μm or more, the degree of dents that may be generated during storage as the optical laminate film 1 tends to increase. Therefore, when the adhesive layer 4 has a thickness of 25 μm or more, the effect of the present invention is more significant. The thickness of the adhesive layer 4 may also be 30 μm or more, 40 μm or more, and more preferably 50 μm or more. The upper limit of the thickness of the adhesive layer 4 is, for example, 150 μm or less. However, the thickness of the adhesive layer 4 is not limited by the above examples, and may be 1 to 200 μm, 5 to 150 μm, and more preferably 10 to 100 μm.

The gel fraction of the adhesive layer 4 is preferably 60% or more, 65% or more, or more than 70%. The upper limit of the gel fraction of the adhesive layer 4 is, for example, 95% or less, or 90% or less. When the gel fraction of the adhesive layer 4 is within these ranges, the above-mentioned suppression effect of the degree of dents can be obtained more reliably.

The weight average molecular weight (Mw) of the sol part in the adhesive layer 4 is, for example, 50,000 or more, and may be 80,000 or more, 100,000 or more, or 150,000 or more, and more preferably 200,000 or more. The upper limit of the weight average molecular weight (Mw) of the sol part is, for example, 1.2 million or less. When the weight average molecular weight (Mw) of the sol part in the adhesive layer 4 is within these ranges, if it is ideally 150,000 or more, the suppression effect of the above-mentioned dent level can be obtained more reliably.

When the indentation hardness of the adhesive layer 4 is 3.0×10 ⁴ Pa or less, the degree of dents that may occur during storage as the optical laminated film 1 tends to increase. Therefore, when the indentation hardness of the adhesive layer 4 is 3.0×10 ⁴ Pa or less, the effect of the present invention is more significant. The indentation hardness of the adhesive layer 4 may also be 1.4×10 ⁴ Pa or less, 1.2×10 ⁴ Pa or less, 1.0×10 ⁴ Pa or less, 8×10 ³ Pa or less, and may be 5×10 ³ Pa or less. The lower limit of the indentation hardness is, for example, 1×10 ² Pa or more.

The indentation hardness of the adhesive layer 4 can be measured by an indentation test according to the nanoindentation method. The details are as follows. The adhesive layer 4 of the evaluation object is cut into a size of about 1 cm×1 cm, and the cut adhesive layer 4 is fixed on the surface of the support as a sample for measurement. The support has a smooth surface as the surface on which the adhesive layer 4 is fixed, and is made of a material having sufficient hardness that does not affect the measurement result, such as glass or metal. The support is, for example, a plate. Next, the above-mentioned measurement sample was mounted on a nanoindenter, and a spherical indenter with a radius of curvature of 10 μm was used to indent the indenter from the surface of the adhesive layer 4 to a depth of 5000 nm at a constant speed at room temperature. Press-in test. The indentation speed of the indenter is set to 1000nm/sec. The value obtained by dividing the maximum load obtained at this time by the projected area of the part of the indenter that is in contact with the sample for measurement when the maximum load is obtained can be used as the indentation hardness of the adhesive layer 4.

The latent variable ΔCr of the adhesive layer 4 at 70°C calculated by the following test is, for example, 65 μm or less, and may also be 50 μm or less, 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, and more It can be 15μm or less. The lower limit of the latent variable ΔCr is, for example, 0.5 μm. Test: To the adhesive layer adhered to the stainless steel test plate on the joint surface of length 20mm×width 20mm, a load of 500gf is applied vertically downward while the test plate is fixed. After starting to apply the load, at each time point after 100 seconds and after 3600 seconds, the latent amount (displacement) of the adhesive layer was measured on the test plate, and they were called Cr ₁₀₀ and Cr _{3600 respectively} . From the measured Cr ₁₀₀ and Cr ₃₆₀₀ , the latent variable ΔCr is calculated using the formula ΔCr=Cr ₃₆₀₀ -Cr ₁₀₀ .

When the latent variable ΔCr of the adhesive layer 4 at 70° C. is within these ranges, the suppression effect of the above-mentioned dent level can be obtained more reliably.

The latent variable ΔCr of the adhesive layer 4 can be evaluated in the following manner (refer to FIGS. 2A and 2B). The laminated body of the adhesive layer 4 and the support film 51 of the evaluation object is cut into a short label shape of 20 mm×30 mm to form a test piece 52. The purpose of the supporting film 51 is to suppress the deformation of the load-applied part of the loaded adhesive layer 4 during the test, so as to more accurately measure the latent variable ΔCr. For the supporting film 51, for example, a resin film such as a polyethylene terephthalate (PET) film can be used. The support film 51 may also be an optical film bonded (bonded) with the adhesive layer 4 in the image display device. The thickness of the support film 51 may be a thickness that does not automatically deform due to the aforementioned load, and is, for example, 20 to 200 μm. The supporting film 51 may be an optical film 3 or a laminated film including the optical film 3. The laminated film is, for example, a laminated body of the optical film 3 and the protective film 2. Next, as shown in FIGS. 2A and 2B, the test piece 52 is adhered to the surface of the stainless steel test plate 53 through the adhesive layer 4 on the joint surface of length 20 mm×width 20 mm. In addition, FIG. 2B is the section BB of FIG. 2A. The adhesion of the test piece 52 to the test plate 53 is implemented so that no air bubbles are mixed between the test plate 53 and the adhesive layer 4. And after sticking by hand, store it in an autoclave at 50°C and 5 atmospheres (absolute pressure) for 15 minutes to homogenize the bonding between the test plate 53 and the adhesive layer 4, and then place it in an atmosphere at 60°C for 2 hours. The maturation is completed. Next, hold the test plate 53 and the test piece 52 vertically with the test plate 53 on top, and place them in a gas environment at 70°C for at least 5 minutes, and then place the test plate 53 at the lower end of the test piece 52 A weight of 500g is fixed in the center, and a load 54 of 500gf is added vertically below. After starting to apply the load 54, at each time point after 100 seconds and 3600 seconds, the drop amount of the weight at each time point is used to measure the latent variable (displacement amount) of the adhesive layer 4 on the test plate 53, They were named Cr ₁₀₀ and Cr _{3600 respectively} . From the measured Cr ₁₀₀ and Cr ₃₆₀₀ , the latent variable ΔCr can be obtained using the formula ΔCr=Cr ₃₆₀₀ -Cr ₁₀₀ . When measuring the falling amount of the weight, a laser displacement meter can be used. In addition, when calculating the latent variable ΔCr, Cr ₁₀₀ is used as the reference, because even if it is the same test piece, when the load 54 is just applied, the drop amount of the weight varies greatly. In order to eliminate as much as possible the inevitable in the initial stage The uneven influence to improve the accuracy of the measurement.

In order to control the latent variable ΔCr of the adhesive layer 4 at 70° C., for example, the following methods can be used alone or in combination. In order to more reliably control the latent variable ΔCr of the adhesive layer 4 at 70°C, the following methods should be combined. However, the control method is not limited by the following examples. ・Method 1 Control the composition of the (meth)acrylic monomer contained in the adhesive composition. For example, when the (meth)acrylic monomer system has a structural unit derived from a (meth)acrylic monomer (C) having a hydroxyl group, and/or a monomer derived from a crosslinkable monomer In the case of the constituent unit of (B), the latent variable ΔCr of the adhesive layer 4 at 70° C. generally shows a tendency to decrease. ・Method 2 Control the type and blending amount of crosslinking agent added to the adhesive composition. By increasing the blending amount of the crosslinking agent, the latent variable ΔCr of the adhesive layer 4 at 70° C. generally shows a tendency to decrease. Moreover, the tendency differs depending on the system of the crosslinking agent, so by combining crosslinking agents of different systems, the latent variable ΔCr of the adhesive layer 4 at 70° C. can be more carefully controlled. For example, when the adhesive composition is solvent-based, the peroxide-based crosslinking agent can inhibit the increase in the elastic modulus of the adhesive layer 4 better than the trifunctional crosslinking agent, maintain stress relaxation, and make it easier to The latent variable ΔCr at 70°C decreases. In addition, the active energy ray-curable adhesive composition hardened by a photopolymerization initiator and a polyfunctional monomer can reduce the latent variable ΔCr at 70°C more easily than a solvent-based adhesive composition. The degree of dents mentioned above is more surely suppressed. ・Method 3 Add (meth)acrylic oligomer to the adhesive composition. By blending (meth)acrylic oligomers, the latent variable ΔCr of the adhesive layer 4 at 70° C. generally shows a tendency to increase.

[Separated Piece] The separator 5 is typically a resin film. The resin constituting the separator 5 is, for example, polyester such as PET, polyolefin such as polyethylene and polypropylene, polycarbonate, acrylic, polystyrene, polyamide, and polyimide. The surface of the separator 5 that is in contact with the adhesive layer 4 may also be peeled off. The peeling treatment can be performed by, for example, polysiloxane. However, the separator 5 is not limited to the above example. The separator 5 is peeled off when the optical laminated film 1 is used, for example, when it is adhered to the image forming layer.

The thickness of the separator 5 is, for example, 20 μm or more, and may be 30 μm or more, 35 μm or more, 40 μm or more, 45 μm or more, 50 μm or more, and more preferably 75 μm or more. When the thickness of the separator 5 is 45 μm or more, especially 75 μm or more, it is possible to more reliably suppress the above-mentioned degree of dents that may be generated in the adhesive layer 4 during storage of the optical laminated film 1. Because the thickness of the separating member 5 can be used to disperse the pressure generated by the trapped foreign matter.

The optical laminated film with adhesive of the present invention may include other layers than the above.

The adhesive layer-attached optical laminated film 1 can be distributed and stored, for example, in the form of a roll formed by winding the film 1 in a strip shape, or in the form of a laminated body of the film 1 in a sheet form.

The optical laminated film 1 with an adhesive layer is typically used in an image display device. The image display device is, for example, a liquid crystal display or an organic EL display. The type and composition of the image display device are not limited.

[Image display device] An example of the image display device of the present invention is shown in FIG. 3. The image display device 6 shown in FIG. 3 has an optical laminate in which a substrate 8, an image forming layer (for example, an organic EL layer) 7, an adhesive layer 4, an optical film 3, and a protective film 2 are sequentially laminated. The image display device 6 includes a portion except for the separator 5 in the optical laminated film 1. The substrate 8 and the image forming layer 7 may have the same structure as the substrate and the image forming layer provided in a known image display device. The image display device 6 has suppressed the above-mentioned degree of dents that can be generated in the adhesive layer 4, and therefore has the advantages of high reliability and fewer optical defects.

The image display device 6 in FIG. 3 is an organic EL display. However, the type and structure of the image display device 6 are not limited.

The image display device of the present invention may have any configuration as long as it includes a portion other than the separator 5 in the optical laminate film 1 with an adhesive layer. Example

The following examples illustrate the present invention in more detail. The present invention is not limited by the examples shown below.

First, the evaluation methods of the optical laminate films and adhesive layers prepared in the examples and comparative examples are shown.

[Weight average molecular weight (Mw)] The measurement of the weight average molecular weight (Mw) of the (meth)acrylic polymer and (meth)acrylic oligomer was performed by GPC under the following measurement conditions. ・Analysis device: Acquity APC manufactured by Waters ・Column: Tosoh, G7000HXL+GMHXL+GMHXL ・Column temperature: 40℃ ・Eluent: Tetrahydrofuran (addition of acid) ・Flow rate: 0.8mL/min ・Injection volume: 100μL ・Detector: Differential Refractometer (RI) ・Standard sample: made by Agilent, polystyrene (PS)

[Latent variable ΔCr at 70℃] The evaluation of the latent variable ΔCr of the prepared adhesive layer at 70°C is implemented by the above method. The support film 51 is a separator used in the production of an optical laminate film. The test board 53 uses a SUS304 board (30mm×75mm, thickness 2.5mm). The laser displacement meter is LK-H057/LK-HD500 manufactured by KEYENCE. In addition, after keeping the test plate 53 upright, place the test plate 53 in a gas atmosphere at 70°C for 5 minutes before starting the test.

[Gel fraction] The evaluation of the gel fraction of the prepared adhesive layer was implemented as follows. First, scrape about 0.2 g from the prepared adhesive layer to obtain a small piece. Next, the obtained small piece was covered with a stretched porous film of polytetrafluoroethylene (NTF1122 manufactured by Nitto Denko, with an average pore diameter of 0.2 μm) and tied with a kite string to obtain a test piece. Next, the weight A of the obtained test piece was measured. The weight A is the total weight of the small pieces of the adhesive layer, the stretched porous film and the kite string. In addition, the total weight B of the stretched porous film and the kite string used is measured in advance. Next, the test piece was immersed in a container filled with ethyl acetate with an inner volume of 50 mL, and left to stand at 23°C for 1 week. After standing, the test piece was taken out from the container and dried in a dryer set at 130°C for 2 hours, and then the weight C of the test piece was measured. Then, from the measured weight A, weight B and weight C, the gel fraction of the adhesive layer is calculated by the formula: gel fraction (weight%)=(CB)/(AB)×100(%) .

[Weight average molecular weight (Mw) of the sol in the adhesive layer] After dissolving the adhesive layer in tetrahydrofuran to form a solution with a concentration of 0.2% by weight, it was allowed to stand at room temperature for 20 hours. Then, after filtering the solution through a membrane filter with a filtration accuracy of 0.45 μm, the obtained filtrate was measured by GPC by measuring the weight average molecular weight (Mw) as the weight average molecular weight of the sol part in the adhesive layer ( Mw). In addition, the measurement conditions of GPC are the same as the conditions when the weight average molecular weight (Mw) is measured for (meth)acrylic polymer and (meth)acrylic oligomer.

[Tensile elastic modulus] The tensile elastic modulus of the protective film was evaluated by a tensile test using a tensile testing machine (AG-IS manufactured by Shimadzu Corporation). The shape of the sample is a short sign with a width of 15 mm × a length of 50 mm, and the initial distance between the clamps is set to 30 mm, and the stretching speed is set to 20 mm/min. In addition, the measurement was performed at 23°C.

[Dent Amount] In the prepared optical laminated film, the degree of dents that can be formed in the adhesive layer is evaluated as the "dent amount" as follows. Prepare a digital thickness gauge with a measuring stand (digital vertical gauge DG-205 manufactured by Ozaki Manufacturing Co., Ltd.), and fix a 5.5mm diameter iron ball with double-sided adhesive tape (No. 500 manufactured by Nitto Denko) on the tip of the measuring hammer. Then, start the thickness gauge to move the measuring hammer up and down, make the iron ball fixed at the front end of the measuring hammer abut the measuring table and release and repeat this action 10 times, then lower the measuring hammer and continue to load the measuring table with a constant load of 100gf By contacting the iron ball for 3 minutes, the double-sided adhesive tape is fully compressed in the thickness direction, and at the same time, the fixed state of the measuring weight and the iron ball is stabilized, thereby enabling high-precision measurement. Next, the contact position of the iron ball with the measuring table after the above treatment is set to the zero point. Next, the prepared optical laminate film was placed on a measuring table with a protective film as an exposed surface. Then start the thickness gauge, lower the measuring weight, and abut the iron ball against the protective film with a constant load of 100gf. The pressure applied to the protective film by abutting the iron ball is about 2 MPa. Measure the displacement of the iron ball from zero at the point in time when the iron ball touches the protective film (0 seconds after contact) with a thickness gauge, and the time point after 60 seconds has passed since that point (60 seconds after contact) ) The displacement of the iron ball from the zero point at this point in time, and the absolute value of the difference is used as the indentation amount of the adhesive layer in the thickness direction, that is, the dent amount. The setting of the zero point and the evaluation of the amount of dents are implemented at 23°C.

Next, the manufacturing method of each adhesive layer of an Example and a comparative example is demonstrated.

The abbreviations or names shown in the following description correspond to the compounds as follows. BA: n-butyl acrylate LA: Lauryl Acrylate MA: methyl acrylate NVP: N-vinylpyrrolidone AA: Acrylic HBA: 4-hydroxybutyl acrylate DCPMA: Dicyclopentyl methacrylate (manufactured by Hitachi Chemical, FA-513M) HEA: 2-hydroxyethyl acrylate 2EHA: 2-ethylhexyl acrylate MMA: methyl methacrylate AIBN: 2,2’-Azobisisobutyronitrile Omnirad651: 2,2-Dimethoxy-2-phenylacetophenone (manufactured by IGM Resins B.V.) Omnirad184: 1-hydroxycyclohexyl phenyl ketone (manufactured by IGM Resins B.V.) D110N: Trimethylolpropane/diisocyanate ester adduct (TAKENATE D110N manufactured by Mitsui Chemicals) C/L: Trimethylolpropane/Toluene diisocyanate (CORONATE L manufactured by Polyurethane Industries, Japan) A-HD-N: Hexanediol diacrylate (manufactured by Shin Nakamura Chemical) Peroxide: Benzyl peroxide (NYPER BMT manufactured by Nippon Oil & Fats) Irganox1010: neopentylerythritol four [3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (made by BASF)

[Production of (meth)acrylic polymer] (Synthesis example 1) 99 parts by weight of BA and 1 part by weight of HBA were fed into a 4-necked flask equipped with a stirring blade, a thermometer, a nitrogen introduction tube, and a cooler. Next, 0.1 parts by weight of AIBN as a polymerization initiator was added to 100 parts by weight of the mixture of BA and HBA, and nitrogen was introduced while stirring slowly to replace nitrogen in the flask, and then the liquid temperature in the flask was maintained at around 55°C The polymerization reaction was carried out for 7 hours. Then, ethyl acetate was added to the obtained reaction liquid to adjust the solid content concentration to 30% by weight, thereby obtaining a solution of (meth)acrylic polymer A1. The weight average molecular weight (Mw) of the (meth)acrylic polymer A1 is 1.6 million.

(Synthesis example 2, 3) The (meth)acrylic polymers A2 and A3 were obtained in the same manner as in Synthesis Example 1, except that the types and amounts of monomers and polymerization initiators shown in Table 1 below were fed into the flask.

[Making (meth)acrylic monomer syrup] (Synthesis example 4) Feed 40 parts by weight of 2EHA, 50 parts by weight of LA, 9 parts by weight of NVP, 1 part by weight of HBA, and 0.05 parts by weight of Ominirad 651 and Omnirad 184, which are photopolymerization initiators, into a nitrogen inlet tube and connected to a B-type viscometer (rotating viscometer). Rotor in a 4-necked flask. Then, the rotor was rotated and nitrogen was introduced to replace the flask with nitrogen, and then irradiated with ultraviolet rays until the viscosity of the polymerization system measured by the viscometer reached about 15 Pa·s, and photopolymerization was performed to obtain a partial polymer containing the monomer group. (Meth) acrylic monomer syrup A4. In addition, the viscometer uses Toki Sangyo's BH model, and the rotation speed of the rotor (rotator No. 5) is set to 10 rpm. In addition, the liquid temperature in the flask was maintained at 30°C.

(Synthesis example 5) A (meth)acrylic monomer syrup A5 was obtained in the same manner as in Synthesis Example 4 except that the types and amounts of monomers and photopolymerization initiators shown in Table 1 below were fed into the flask.

[Making (meth)acrylic oligomers] (Synthesis Example 6) 95 parts by weight of BA, 3 parts by weight of MA, 2 parts by weight of AA, 0.1 parts by weight of AIBN as a polymerization initiator, and 140 parts by weight of toluene were fed into a 4-necked flask equipped with a stirring blade, a thermometer, a nitrogen introduction tube, and a cooler. Then, while slowly stirring, nitrogen was introduced into the flask to replace nitrogen in the flask, and then the liquid temperature in the flask was maintained at around 70°C for 8 hours to perform a polymerization reaction to obtain a solution of (meth)acrylic oligomer B1. The weight average molecular weight of the (meth)acrylic oligomer B1 is 4500.

(Synthesis Example 7) 60 parts by weight of DCPMA and 40 parts by weight of MMA as monomer components, 3.5 parts by weight of α-thioglycerin as a chain transfer agent, and 100 parts by weight of toluene as a polymerization solvent were mixed, and stirred at 70° C. for 1 hour in a nitrogen atmosphere. Next, 0.2 parts by weight of AIBN as a thermal polymerization initiator was added, and after reacting at 70°C for 2 hours, the temperature was raised to 80°C and reacted for 2 hours. Then, the reaction liquid was heated to 130° C., toluene, chain transfer agent, and unreacted monomer were dried and removed to obtain (meth)acrylic oligomer B2.

Table 1 below shows the composition of the (meth)acrylic polymer, (meth)acrylic monomer syrup, and (meth)acrylic oligomer prepared in each synthesis example (monomer feed Ratio) and weight average molecular weight (Mw).

[Table 1]

[Making adhesive layer] (Manufacturing examples 1 to 8, 11) The (meth)acrylic polymer, (meth)acrylic oligomer, crosslinking agent, and additives were mixed so as to have the composition shown in Table 2 below to obtain a solvent-based adhesive composition. Next, the obtained adhesive composition was coated on the surface of a PET film (thickness 38μm, 50μm or 75μm) belonging to a separator, and then dried in an air circulation constant temperature oven set at 155°C for 2 minutes to form a manufacturing example 1~8,11 adhesive layer (thickness 50μm). The adhesive composition is coated with a fountain-type coating machine.

(Production Examples 9, 10) The (meth)acrylic monomer syrup, crosslinking agent, and additives were mixed so as to have the composition shown in Table 2 below to obtain a mixture. Next, after coating the above mixture on the surface of a PET film (thickness 38 μm) that is a separator, another layer of the above PET film is placed on the coating film of the mixture, and the coating film is sandwiched by a pair of PET films. Furthermore, ultraviolet rays were irradiated under irradiation conditions of an illuminance of 4 mW/cm ² and a light quantity of 1200 mJ/cm ^{2 to} harden the coating film to form an adhesive layer (thickness 50 μm). After the adhesive layer is formed, the other PET film is peeled off to expose the adhesive layer.

[Table 2]

Table 3 below shows the evaluation results of each adhesive layer prepared in Manufacturing Examples 1-11.

[table 3]

[Making optical laminate film] According to the combinations shown in Table 4 below, the separators and adhesive layers, optical films, and protective films prepared in Manufacturing Examples 1 to 11 were sequentially laminated to obtain Examples 1 to 12 and Comparative Examples 1 to 3 Optical multilayer film. However, in Comparative Example 1, no protective film was provided. The optical film uses a polarizer protective film (thickness 20μm), polarizer (thickness 5μm), λ/2 plate (1/2 wavelength plate, thickness 3μm) and λ/4 plate laminated in order from the side where it is joined to the protective film (1/4 wavelength plate, thickness 3μm) 31μm thick polarizing plate. The protective film used a PET film (thickness 25 μm, 38 μm, or 50 μm) in Examples 1 to 12 and Comparative Example 3, and a polyethylene film (thickness 30 μm) in Comparative Example 2. The protective film is bonded to the optical film through the acrylic adhesive layer (thickness 10 μm). In addition, the layers and optical films constituting the optical film are prepared as follows.

(λ/4 plate and λ/2 plate) The retardation film, which is a laminate of λ/4 plate (1/4 wavelength plate) and λ/2 plate (1/2 wavelength plate), uses a polymerizable liquid crystal material that displays a nematic liquid crystal phase after forming an alignment film (BASF company System, PaliocolorLC242). The details are as follows. After dissolving the above polymerizable liquid crystal material and photopolymerization initiator (made by BASF, IRGACURE 907) in toluene, for the purpose of improving coating properties, a fluorine-based surfactant (made by DIC) is further added at 0.1 to 0.5% by weight according to the thickness of the liquid crystal. MEGAFACE), and a coating liquid L was prepared. The solid content concentration of the coating liquid L was 25% by weight.

Next, the manufacturing apparatus 200 of the retardation film shown in FIG. 4 is prepared. The manufacturing apparatus 200 includes a supply turntable 221 for supplying a strip-shaped PET substrate 214, pressure rollers 224, 234, shaping rollers 230, 240, peeling rollers 226, 236, conveying rollers 231, molds 222, 229, 232, 239, and borrowing Ultraviolet irradiation devices 225, 227, 235, 237 that irradiate ultraviolet rays from high-pressure mercury lamps. Next, the mold 222 is used to apply the ultraviolet curable resin solution 210 to one surface of the PET substrate 214 unwound from the supply turntable 221. Then, the coating film is brought into contact with the shaping roller 230 by the pressure roller 224, and the PET substrate 214 is transported along the shaping roller 230 while the two are in contact with each other. The side of the PET substrate 214 is irradiated with ultraviolet rays to harden the coating film. Formed on the conveying surface of the PET substrate 214 in the shaping roller 230 are linear concavities and convexities that can form a λ/4 plate when the orientation film of the polymerizable liquid crystal material is further formed (relative to the MD direction of the PET substrate 75 ° direction extension), by the above curing, a cured film of ultraviolet curable resin having a shape corresponding to the unevenness on the exposed surface can be formed. Next, after peeling the PET substrate 214 with the cured film formed on the forming roller 230 by the peeling roller 226, the coating liquid L is applied to the exposed surface of the cured film by the mold 229, and the ultraviolet irradiation device 227 is used to irradiate ultraviolet rays. , Make the coating film directionally harden. In this way, a λ/4 plate (thickness 3 μm) composed of a cured film of ultraviolet curable resin and a oriented cured film of polymerizable liquid crystal material can be formed on the PET substrate 214.

Next, the PET substrate 214 formed with the λ/4 plate is transported by the transport roller 231, and the exposed surface of the λ/4 plate is coated with the ultraviolet curable resin solution 212 with the mold 232 to form a coating film. Then, the coating film is brought into contact with the shaping roller 240 by the pressure roller 234, and the PET substrate 214 is transported along the shaping roller 240 in the state in which the two are in contact, and the ultraviolet irradiation device 235 removes The side of the PET substrate 214 is irradiated with ultraviolet rays to harden the coating film. On the conveying surface of the PET substrate 214 in the shaping roller 240, there are formed linear asperities that can form a λ/2 plate when the alignment film of the polymerizable liquid crystal material is further formed (relative to the MD direction of the PET substrate 15 ° direction extension), by the above curing, a cured film of ultraviolet curable resin having a shape corresponding to the unevenness on the exposed surface can be formed. Next, after peeling the PET substrate 214 with the cured film formed on the forming roller 240 by the peeling roller 236, the coating liquid L is applied to the exposed surface of the cured film by the mold 239, and the ultraviolet irradiation device 237 is used to irradiate ultraviolet rays. , Make the coating film directionally harden. In this way, a λ/2 plate (thickness 3μm) composed of a cured film of ultraviolet curable resin and a oriented cured film of polymerizable liquid crystal material can be further formed on the λ/4 plate of the PET substrate 214 to obtain Layered body (b).

(Polarizing film) The polarizing film is produced in the following manner, and the polarizing film is a laminate of a polarizer and a polarizer protective film.

An amorphous IPA copolymer PET film (thickness 100 μm) with 7 mol% isophthalic acid (IPA) units was prepared as a thermoplastic resin substrate, and the surface was subjected to corona treatment (58 W/m ² /min). In addition, 1% by weight of acetyl acetyl modified PVA (manufactured by Nippon Synthetic Chemical Industry, GOHSEFIMER Z200, average polymerization degree 1200, saponification degree 98.5 mol%, acetylation degree 5 mol%) will be added here. The PVA (polymerization degree 4200, saponification degree 99.2%) was dissolved in water to obtain a PVA coating solution with a concentration of 5.5% by weight. Next, the corona-treated surface of the IPA copolymer PET film was coated with the above-mentioned PVA coating solution so that the film thickness after drying became 12μm, and the coating film was dried by hot air drying at 60°C for 10 minutes to obtain A laminate composed of a substrate and a PVA layer on the substrate.

Next, the obtained laminate was subjected to free end extension (air-assisted extension) at 130°C at a stretch magnification of 1.8 times in air to obtain a stretched laminate. Next, the stretched laminate was immersed in a boric acid insoluble aqueous solution with a liquid temperature of 30°C for 30 seconds to insolubilize the PVA layer. The content of boric acid in the boric acid insoluble aqueous solution is 3 parts by weight with respect to 100 parts by weight of water. Next, the stretched laminate in which the PVA layer has been insolubilized is dyed to obtain a colored laminate. Dyeing is performed by immersing the stretched laminate in a dyeing solution containing iodine and potassium iodide at a temperature of 30°C. In the above dyeing, the PVA layer contained in the stretch laminate is dyed with iodine. The dyeing time is adjusted within the range of 40~44% of the monomer transmittance of the PVA layer constituting the polarizer finally obtained. The dyeing solution is an aqueous solution with an iodine concentration of 0.1 to 0.4% by weight and a potassium iodide concentration of 0.7 to 2.8% by weight. The ratio of potassium iodide concentration to iodine concentration in the dyeing solution is 7. Next, the colored laminate was immersed in a boric acid cross-linking aqueous solution at a liquid temperature of 30° C. for 60 seconds to form a cross-linked structure between PVA molecules in the iodine-adsorbed PVA layer, and cross-linking treatment was performed. Both the boric acid content and the potassium iodide content in the boric acid crosslinking aqueous solution are set to 3 parts by weight relative to 100 parts by weight of water.

Next, the colored layered body after the crosslinking treatment was stretched in a boric acid aqueous solution at a stretching temperature of 70° C. and a stretching ratio of 3.05 times (boric acid water stretching) to obtain a stretched layered body with a final stretching ratio of 5.50 times. The extension direction of the boric acid water extension is consistent with the extension direction of the air auxiliary extension implemented at the beginning. Next, the stretched laminate after stretching is taken out from the boric acid aqueous solution, and the boric acid adhering to the surface of the PVA layer is washed with a potassium iodide solution (potassium iodide content is 4 parts by weight relative to 100 parts by weight of water). Then, the washed stretched laminate was dried with hot air at 60° C. to obtain a laminate of a substrate and a polarizer (thickness 5 μm) formed on the substrate.

Next, a stretched film of methacrylic resin (thickness 20 μm, moisture permeability 160 g/m ² ) having glutarimide ring units was prepared as a polarizer protective film. Next, the prepared polarizer protective film is bonded to the exposed surface of the polarizer in the laminate produced above to obtain a laminate (c) of the substrate and the polarizer film having the polarizer and the polarizer protective film. When joining the polarizer and the polarizer protective film, a well-known acrylic adhesive is used.

Next, using the laminate (b) and the laminate (c) prepared above, an optical film was produced in the following manner. First, the base material is peeled off from the laminate (c) to expose the polarizer. Next, the exposed polarizer and the λ/2 plate of the laminate (b) were joined with a well-known acrylic adhesive to obtain an optical film. In addition, the bonding of the optical film and the adhesive layer was performed after peeling the PET substrate 214 from the laminate (b) to expose the λ/4 plate.

Table 4 below shows the composition and evaluation results of each optical laminated film of the Examples and Comparative Examples.

[Table 4]

As shown in Table 4, the amount of dents has been reduced in the optical laminated film of the example.

Industrial availability The optical laminated film with adhesive layer of the present invention can be used to manufacture image display devices.

1: Optical laminated film with adhesive layer 2: Protective film 3: Optical film 4: Adhesive layer 5: Separate parts 6: Video display device 7: image cambium 8: substrate 51: Support film 52: Test strip 53: test board 54: Load 200: Manufacturing device 210,212: solution 214: PET substrate 221: Supply Carousel 222,229,232,239: Mould 224,234: pressure roller 225,227,235,237: UV irradiation device 226,236: Peel roller 230,240: shaping roller 231: conveyor roller B-B: cross section L: Coating liquid

Fig. 1 is a cross-sectional view schematically showing an example of the optical laminate film with an adhesive layer of the present invention. FIG. 2A is a schematic diagram for explaining the method of measuring the latent variable ΔCr of the adhesive layer. Fig. 2B is a schematic diagram for explaining the method of measuring the latent variable ΔCr of the adhesive layer. 3 is a cross-sectional view schematically showing an example of the image display device of the present invention. FIG. 4 is a schematic diagram for explaining the method of manufacturing the λ/4 plate and the λ/2 plate used in the embodiment.

1: Optical laminated film with adhesive layer

2: Protective film

3: Optical film

4: Adhesive layer

5: Separate parts

Claims (8)

An optical laminated film with an adhesive layer, which is laminated with a protective film, an optical film, an adhesive layer, and a separator in sequence; Among them, the thickness of the aforementioned optical film is 80μm or less, The thickness of the protective film is 30 μm or more, and the tensile modulus of the protective film is 1 GPa or more. The optical laminated film with an adhesive layer of claim 1, wherein the protective film is a polyester film. The optical laminated film with an adhesive layer of claim 1 or 2, wherein the thickness of the adhesive layer is 25 μm or more. The optical laminate film with an adhesive layer according to any one of claims 1 to 3, wherein the thickness of the aforementioned separator is 45 μm or more. The optical laminate film with an adhesive layer according to any one of claims 1 to 4, wherein the gel fraction of the adhesive layer is 60% or more. The optical laminated film with an adhesive layer according to any one of claims 1 to 5, wherein the weight average molecular weight (Mw) of the sol in the adhesive layer is 50,000 or more. For the optical laminated film with adhesive layer of any one of claims 1 to 6, the latent variable ΔCr of the adhesive layer at 70°C calculated by the following test is 50 μm or less; test: The bonding surface of 20mm×width 20mm is adhered to the adhesive layer of the stainless steel test plate, and a load of 500gf is applied vertically below the test plate in the state where the test plate has been fixed; after the load is started, after 100 seconds, it will reach 3600 At each time point after seconds, the latent variable (displacement) of the adhesive layer was measured on the test board, and set to Cr ₁₀₀ and Cr _{3600 respectively} ; from the measured Cr ₁₀₀ and Cr ₃₆₀₀ , use the formula ΔCr=Cr ₃₆₀₀ -Cr ₁₀₀ Find the latent variable ΔCr. An image display device having a portion other than the aforementioned separator in the optical laminated film with an adhesive layer as claimed in any one of claims 1 to 7.

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