CN117295987A

CN117295987A - Optical film, method for producing optical film, optical member, and image display device

Info

Publication number: CN117295987A
Application number: CN202280031207.8A
Authority: CN
Inventors: 平间进
Original assignee: Nippon Shokubai Co Ltd
Current assignee: Nippon Shokubai Co Ltd
Priority date: 2021-05-31
Filing date: 2022-05-31
Publication date: 2023-12-26
Also published as: KR20240006695A; WO2022255391A1; JPWO2022255391A1; TW202306780A

Abstract

An optical film comprising a resin film and an easy-to-adhere layer formed on the surface of the resin film, wherein the easy-to-adhere layer comprises a binder resin, a polyamine and fine particles, wherein the polyamine is a polymer having 2 or more amino groups, wherein the 2 or more amino groups comprise at least 1 selected from the group consisting of secondary amino groups and tertiary amino groups, and wherein the content of the polyamine in the easy-to-adhere layer is 0.0090 to 1.4100 wt%.

Description

Optical film, method for producing optical film, optical member, and image display device

Technical Field

The invention relates to an optical film, a method for manufacturing the optical film, an optical member, and an image display device.

Background

Liquid crystal display devices and organic EL display devices are used for various image display applications such as monitors and televisions. Polarizing plates are used in liquid crystal display devices. In the organic EL display device, a polarizing plate and a 1/4 wavelength plate are used in order to prevent reflection of external light. The polarizing plate generally includes a polarizing element and a polarizing element protective film attached to at least one surface of the polarizing element via an adhesive layer.

As a protective film for a polarizing element, a cellulose film has been widely used. In recent years, films made of acrylic, polyester, polycarbonate, cyclic polyolefin, and the like have also been used. These films have lower moisture permeability and excellent durability than cellulose films, but the adhesion of these films to PVA-based polarizing elements is inferior to cellulose films. Therefore, a method of providing an easy-to-adhere layer on the surface of these films to improve the adhesion between the films and the polarizing element has been proposed. For example, patent document 1 describes: by providing the surface of the acrylic film with the adhesive layer containing the fine particles and the binder resin, not only the adhesion between the acrylic film and the polarizing element can be improved, but also blocking can be suppressed.

Patent document 2 describes that: the easy-to-adhere layer contains alkali components such as ammonia, amine and the like; although an excessive amount of the alkali component remaining in the adhesive layer may deteriorate the polarizing element, the alkali component may also function as a catalyst for promoting the reaction of the binder resin (precursor); the alkali component improves the dispersibility of the inorganic fine particles in the adhesive layer. The description is: by applying the composition for easy adhesion to the film substrate and then heating the composition, the alkali component can be volatilized and removed, and the residual alkali component in the easy-to-adhere layer can be reduced.

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2010-55052

Patent document 2: japanese patent laid-open No. 2020-16872

Disclosure of Invention

Problems to be solved by the invention

However, for example, the adhesion between the film and the easy-to-adhere layer and the uniformity of the easy-to-adhere layer have not been sufficiently studied. In addition, for example, in the technique described in patent document 2, it is difficult to adjust the amount of the residual alkali component.

Means for solving the problems

In view of the above, the present inventors have conducted intensive studies and as a result, completed the inventions shown in the following [1] to [9 ].

[1] An optical film comprising a resin film and an easily adhesive layer formed on the surface of the resin film, wherein the easily adhesive layer contains a binder resin, a polyamine and fine particles, the polyamine is a polymer having 2 or more amino groups, the 2 or more amino groups contain at least 1 selected from the group consisting of secondary amino groups and tertiary amino groups, and the content of the polyamine in the easily adhesive layer is 0.0090 to 1.4100 wt%.

[2] The optical film according to [1], wherein the binder resin comprises a polyurethane resin.

[3] The optical film according to [1] or [2], wherein the 2 or more amino groups include a primary amino group, the secondary amino group, and the tertiary amino group.

[4] The optical film according to any one of [1] to [3], wherein the polyamine comprises a polyalkyleneimine.

[5] The optical film according to [4], wherein the polyalkyleneimine contains a primary amino group, the secondary amino group and the tertiary amino group, and has a branched structure.

[6] The optical film according to any one of [1] to [5], wherein the resin film contains a (meth) acrylic polymer.

[7] An optical member comprising the optical film of any one of [1] to [6 ].

[8] An image display device comprising the optical film of any one of [1] to [6 ].

[9] A method for producing an optical film according to any one of [1] to [6], wherein a coating film of the composition is formed by coating an adhesive composition containing a binder resin, a polyamine and fine particles on a surface of a resin film, and the coating film is dried to form an adhesive layer containing the binder resin, the polyamine and the fine particles on the surface of the resin film, wherein the polyamine is a polymer having 2 or more amino groups, and the 2 or more amino groups contain at least 1 selected from the group consisting of secondary amino groups and tertiary amino groups.

ADVANTAGEOUS EFFECTS OF INVENTION

The optical film of the present invention has a resin film and an easy-to-adhere layer, and is excellent in adhesion. In addition, the alkali component contained in the easy-to-adhere layer of the optical film of the present invention is a polymer that is not easily volatilized during the production of the optical film, and thus the amount of the alkali component contained in the easy-to-adhere layer can be easily controlled.

Detailed Description

Unless otherwise specified, the term "resin" in the present specification is a broader concept than "polymer". The resin may be composed of, for example, 1 or 2 or more kinds of polymers, or may contain materials other than polymers, for example, an ultraviolet absorber, an antioxidant, an additive such as a filler, a compatibilizer, a stabilizer, and the like, as required.

[ optical film ]

The optical film of the present embodiment includes a resin film and an easy-to-adhere layer formed on the surface of the resin film.

[ resin film ]

The resin film is not particularly limited, and is, for example, a film made of a material such as a (meth) acrylic polymer, polyester, polycarbonate, or cyclic polyolefin. Among them, an acrylic resin film obtained by molding an acrylic resin containing a (meth) acrylic polymer is preferable. The content of the (meth) acrylic polymer in the acrylic resin is usually 30% by weight or more, preferably 50% by weight or more, more preferably 70% by weight or more, particularly preferably 90% by weight or more, and most preferably 95% by weight or more.

The (meth) acrylic polymer is a polymer having structural units ((meth) acrylate units) derived from a (meth) acrylate monomer. The content of the (meth) acrylate unit in the (meth) acrylic polymer is usually 10% by weight or more, preferably 30% by weight or more, more preferably 50% by weight or more, and particularly preferably 70% by weight or more. The weight average molecular weight of the (meth) acrylic polymer is preferably 1 to 50 tens of thousands, more preferably 5 to 30 tens of thousands.

The (meth) acrylate unit is, for example, a structural unit derived from each monomer of methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2,3,4,5, 6-pentahydroxyhexyl (meth) acrylate, and 2,3,4, 5-tetrahydroxypentyl (meth) acrylate. The (meth) acrylic polymer preferably has a structural unit derived from methyl (meth) acrylate, in which case the optical properties and thermal stability of the finally obtained optical film are improved. The (meth) acrylic polymer may have 2 or more (meth) acrylate units.

The (meth) acrylic polymer may have a structural unit other than the (meth) acrylate unit. Such structural units are, for example, structural units derived from monomers of styrene, vinyltoluene, α -methylstyrene, α -hydroxymethylstyrene, α -hydroxyethylstyrene, acrylonitrile, methacrylonitrile, ethylene, propylene, 4-methyl-1-pentene, vinyl acetate, 2-hydroxymethyl-1-butene, methyl vinyl ketone, N-vinylpyrrolidone, N-vinylcarbazole. The (meth) acrylic polymer may have 2 or more of these structural units. When the (meth) acrylic polymer has an N-vinyl pyrrolidone unit or an N-vinyl carbazole unit, the degree of freedom in controlling the wavelength dispersion of birefringence in the optical film is improved. For example, in the visible light region, a retardation film exhibiting wavelength dispersion (so-called inverse wavelength dispersion) in which birefringence is smaller (the absolute value of the phase difference is smaller) as the wavelength of light is shorter can be obtained. The retardation film is suitable as a positive retardation film.

The (meth) acrylic polymer may have a ring structure in the main chain. Such a (meth) acrylic polymer is obtained, for example, by copolymerizing a (meth) acrylic acid ester monomer with a monomer having a ring structure, or polymerizing a monomer group containing a (meth) acrylic acid ester monomer and then performing a cyclization reaction. When the main chain of the (meth) acrylic polymer has a ring structure, the total content of the (meth) acrylic acid ester unit and the ring structure may be 50% by weight or more.

When the ring structure is introduced into the main chain by the cyclization reaction after the polymerization, the (meth) acrylic polymer is preferably formed by copolymerization of a monomer group including a monomer having a hydroxyl group and/or a carboxylic acid group. Examples of the monomer having a hydroxyl group include methyl 2- (hydroxymethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, isopropyl 2- (hydroxymethyl) acrylate, butyl 2- (hydroxymethyl) acrylate, methyl 2- (hydroxyethyl) acrylate, methallyl alcohol and allyl alcohol. Examples of the monomer having a carboxylic acid group include acrylic acid, methacrylic acid, crotonic acid, 2- (hydroxymethyl) acrylic acid, and 2- (hydroxyethyl) acrylic acid. More than 2 kinds of these monomers can be used. The monomer need not be changed to a ring structure at the time of the cyclization reaction, and the (meth) acrylic polymer after the cyclization reaction may have a structural unit derived from these monomers.

The (meth) acrylic polymer preferably has a ring structure in the main chain. Thus, the acrylic resin film is excellent in heat resistance and hardness. In addition, since a stretched film exhibits a large retardation when produced, it is suitable for use as a retardation film or a polarizing element protective film having the function of a retardation film.

The ring structure is, for example, at least 1 selected from the group consisting of an N-substituted maleimide structure, a maleic anhydride structure, a glutarimide structure, a glutaric anhydride structure and a lactone ring structure. The N-substituted maleimide structure is, for example, a cyclohexylmaleimide structure, a methylmaleimide structure, a phenylmaleimide structure, a benzylmaleimide structure. From the viewpoint of heat resistance of the optical film, the ring structure is preferably a lactone ring structure, a cyclic imide structure (e.g., an N-alkyl substituted maleimide structure, a glutarimide structure), a cyclic anhydride structure (e.g., a maleic anhydride structure and a glutarimide structure). The optical film of the present embodiment can be used as a retardation film. The ring structure is preferably a lactone ring structure, a glutarimide structure, or a glutarimide structure, from the viewpoint of imparting a positive retardation to an optical film as a retardation film. The ring structure is preferably a lactone ring structure in view of improving the wavelength dispersion of birefringence in the retardation film.

The following general formula (1) shows a glutaric anhydride structure and a glutarimide structure.

[ chemical 1]

R in the above general formula (1) ¹ 、R ² Each independently is a hydrogen atom or a methyl group, X ¹ Is an oxygen atom or a nitrogen atom. X is X ¹ R is an oxygen atom ³ Absence, X ¹ R is a nitrogen atom ³ Is a hydrogen atom, a straight-chain alkyl group having 1 to 6 carbon atoms, a cyclopentyl group, a cyclohexyl group, a benzyl group or a phenyl group.

X ¹ When the oxygen atom is an oxygen atom, the ring structure represented by the general formula (1) is a glutaric anhydride structure. The glutaric anhydride structure can be formed, for example, by dealcoholizing and cyclized condensing a copolymer of (meth) acrylic acid ester and (meth) acrylic acid in a molecule. X is X ¹ When the nitrogen atom is a nitrogen atom, the ring structure represented by the general formula (1) is a glutarimide structure. The glutarimide structure can be formed, for example, by imidizing a (meth) acrylate polymer with an imidizing agent such as methylamine.

The following general formula (2) shows a maleic anhydride structure and an N-substituted maleimide structure.

[ chemical 2]

R in the above general formula (2) ⁴ 、R ⁵ Each independently is a hydrogen atom or a methyl group, X ² Is an oxygen atom or a nitrogen atom. X is X ² R is an oxygen atom ⁶ Absence, X ² R is a nitrogen atom ⁶ Is a hydrogen atom, a straight-chain alkyl group having 1 to 6 carbon atoms, a cyclopentyl group, a cyclohexyl group, a benzyl group or a phenyl group.

X ² When the ring structure is an oxygen atom, the ring structure represented by the general formula (2) is a maleic anhydride structure. The maleic anhydride structure can be obtained, for example, by copolymerizing maleic anhydride with a (meth) acrylate And (5) forming. X is X ² When the compound is a nitrogen atom, the ring structure represented by the general formula (2) is an N-substituted maleimide structure.

In the method of forming the ring structures illustrated in the descriptions of the general formulae (1) and (2), the polymers for forming the respective ring structures all have (meth) acrylate units as structural units, and thus the resulting resin is an acrylic resin.

The following general formula (3) shows a lactone ring structure.

[ chemical 3]

In the above general formula (3), R ⁷ 、R ⁸ And R is ⁹ Each independently is a hydrogen atom or an organic residue having a carbon number in the range of 1 to 20. The organic residue may comprise an oxygen atom.

The organic residue in the general formula (3) is, for example, an unsaturated aliphatic hydrocarbon group having 2 to 20 carbon atoms such as an alkyl group having 1 to 20 carbon atoms such as a methyl group, an ethyl group, and a propyl group, an aromatic hydrocarbon group having 6 to 20 carbon atoms such as a phenyl group, and a naphthyl group, and one or more hydrogen atoms in the alkyl group, the unsaturated aliphatic hydrocarbon group, and the aromatic hydrocarbon group may be substituted with at least 1 group selected from a hydroxyl group, a carboxyl group, an ether group, and an ester group.

The general formula (3) shows a lactone ring structure of a 6-membered ring, but the lactone ring structure is not limited thereto. For example, a 4 to 8 membered ring is possible. The ring structure is excellent in stability, and is preferably a 5-membered ring or a 6-membered ring, more preferably a 6-membered ring.

When the main chain of the (meth) acrylic polymer has a ring structure, the content of the ring structure in the polymer is not particularly limited, but is usually 5 to 90% by weight, preferably 10 to 70% by weight, more preferably 10 to 60% by weight, and still more preferably 10 to 50% by weight. When the content of the ring structure is large (for example, 10 wt% or more), the heat resistance, solvent resistance and surface hardness of the film are particularly excellent. When the content of the ring structure is small (for example, 70 wt% or less), the acrylic resin film is particularly excellent in ease of stretching and operability in production.

When the ring structure of the main chain is other than a lactone ring structure (for example, an N-substituted maleimide structure, a maleic anhydride structure, a glutarimide structure, and a glutarimide structure), the content of the ring structure is not particularly limited, but is, for example, 5 to 90% by mass, preferably 10 to 70% by mass, more preferably 10 to 60% by mass, and still more preferably 10 to 50% by mass.

When the ring structure of the main chain is a lactone ring structure, the content of the ring structure is not particularly limited, and is, for example, 5 to 90% by mass, preferably 10 to 80% by mass, more preferably 10 to 70% by mass, and still more preferably 10 to 60% by mass.

The (meth) acrylic polymer having a main chain with a ring structure can be formed by a known method. The (meth) acrylic polymer having a lactone ring structure in the main chain is, for example, a polymer described in JP-A-2000-230016, JP-A-2001-151814, JP-A-2002-120326, JP-A-2002-254544, and JP-A-2005-146084, and can be formed by the method described in the above-mentioned publications.

The (meth) acrylic polymer having a glutaric anhydride structure in the main chain is, for example, a polymer described in Japanese patent application laid-open No. 2006-283013, japanese patent application laid-open No. 2006-335902, and Japanese patent application laid-open No. 2006-274118, and can be formed by the method described in the above publication.

The (meth) acrylic polymer having a main chain with a glutarimide structure is, for example, a polymer described in Japanese patent application laid-open No. 2006-309033, japanese patent application laid-open No. 2006-317560, japanese patent application laid-open No. 2006-328329, japanese patent application laid-open No. 2006-328334, japanese patent application laid-open No. 2006-337491, japanese patent application laid-open No. 2006-337492, japanese patent application laid-open No. 2006-337493, japanese patent application laid-open No. 2006-337569, and Japanese patent application laid-open No. 2007-009182, and can be formed by the method described in the above publication.

In the case of forming various polymers in the acrylic resin, the monomer raw material, the polymerization initiator, the auxiliary raw material such as the catalyst, and the solvent used in the polymerization are preferably used after filtration as much as possible in terms of reducing foreign matters in the polymer and in terms of filtering at a stage of low viscosity as compared with the filtration after the polymerization. The filtration may be carried out by directly filtering the solution in the case of a liquid or by dissolving the solution in a solvent or the like used in the polymerization and passing the solution through various filters such as a membrane filter or a hollow fiber membrane filter, or by filtering the solution alone or by preparing a mixture and then filtering the mixture. The filtration accuracy in this case is preferably 5.0 μm or less, more preferably 1.0 μm or less, and still more preferably 0.5 μm or less.

The acrylic resin may be formed by combining a (meth) acrylic polymer with other polymers according to desired physical properties, uses, and the like. The other polymer is not particularly limited, and may be a thermoplastic polymer, a curable polymer, or a combination thereof. Other polymers may be used alone or in combination of 2 or more.

As a specific example of the other polymer(s), examples thereof include other (meth) acrylic polymers having a different composition ratio to (meth) acrylic polymers, a different molecular weight, or a different copolymerization composition, olefinic polymers (e.g., polyethylene, polypropylene, ethylene-propylene copolymer, poly (4-methyl-1-pentene), etc.), halogen polymers (e.g., polyvinyl chloride, polyvinylidene chloride, halogenated vinyl polymers such as polyvinyl chloride), etc.), styrene polymers [ e.g., polystyrene, styrene copolymers (e.g., styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene block copolymer (ABS resin), acrylate-styrene-acrylonitrile copolymer (ASA resin), etc. ], and the like polyester polymer (for example, aromatic polyester such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate), polyamide polymer (for example, aliphatic polyamide polymer such as polyamide 6, polyamide 66, and polyamide 610), polyacetal polymer, polycarbonate polymer, polyphenylene ether polymer, polyphenylene sulfide polymer, polyether ether ketone polymer, polysulfone polymer, polyether sulfone polymer, and copolymer comprising a polymer block having a unit derived from diene and/or olefin and a polymer block having a unit derived from an aromatic vinyl monomer [ for example, styrene-ethylene/butylene-styrene block copolymer (SEBS) ], styrene-ethylene/butylene-styrene block copolymer (SEBS), styrene-butadiene/butylene-styrene block copolymers (SBS) and the like ], cellulose-based polymers (cellulose derivatives), thermoplastic elastomers (styrene-based elastomers and the like), and the like.

In the case where the acrylic resin contains a polymer other than the (meth) acrylic polymer, the form of the (meth) acrylic polymer and the other polymer may be a polymer blend, and the (meth) acrylic polymer and the other polymer may be chemically bonded. In this case, a block copolymer, a graft copolymer, or the like may be formed from the (meth) acrylic polymer and other polymers.

When the acrylic resin contains other polymers in addition to the (meth) acrylic polymer, the content of the other polymers may be, for example, 90 mass% or less (for example, 0.1 to 85 mass%), 80 mass% or less (for example, 0.5 to 70 mass%), preferably 60 mass% or less (for example, 1 to 55 mass%), 50 mass% or less (for example, 2 to 45 mass%), 30 mass% or less (for example, 2 to 25 mass%), 20 mass% or less (for example, 2 to 15 mass%), or the like.

For example, when the acrylic resin contains a styrene-based polymer, the positive retardation exhibited by a (meth) acrylic polymer having a ring structure in the main chain can be offset by the negative retardation exhibited by the styrene-based polymer by using an acrylic resin film made of the acrylic resin as a stretched film. By adjusting the content of the styrene polymer in the acrylic resin film, a negative retardation film and a low retardation polarizing element protective film can be produced. In the case where the acrylic resin film contains a styrene-based polymer, the styrene-based polymer is preferably a styrene-acrylonitrile copolymer from the viewpoint of compatibility with the (meth) acrylic polymer. When the acrylic resin film contains an ABS resin or an ASA resin, the acrylic resin film can be made a negative retardation film or a film with a low retardation by adjusting the content of the ABS resin or the ASA resin in the acrylic resin film, and the flexibility can be improved.

The acrylic resin may contain materials other than polymers, for example, additives. Additives are, for example: antioxidants such as hindered phenols, phosphorus, sulfur, etc.; stabilizers such as a light stabilizer, a weather stabilizer, and a heat stabilizer; reinforcing materials such as glass fibers and carbon fibers; ultraviolet absorbers such as phenyl salicylate, (2, 2' -hydroxy-5-methylphenyl) benzotriazole, and 2-hydroxybenzophenone; a near infrared ray absorber; flame retardants such as tris (dibromopropyl) phosphate, triallyl phosphate, antimony oxide, and the like; antistatic agents comprising anionic, cationic and nonionic surfactants; colorants such as inorganic pigments, organic pigments, dyes, and the like; an organic filler and an inorganic filler; an anti-blocking agent; a resin modifier; an organic filler and an inorganic filler; a plasticizer; a lubricant; a phase difference reducing agent.

The content of the additive in the acrylic resin is preferably 0 to 5% by weight, more preferably 0 to 2% by weight, and still more preferably 0 to 0.5% by weight.

The Tg (glass transition temperature) of the acrylic resin is preferably 100 ℃ or higher, more preferably 110 ℃ or higher, still more preferably 115 ℃ or higher, particularly preferably 120 ℃ or higher. The upper limit of Tg of the acrylic resin is not particularly limited, but is preferably 170 ℃ or less in view of stretchability when the acrylic resin film is formed.

The acrylic resin film is obtained by molding an acrylic resin. The thickness of the acrylic resin film is not particularly limited, but is preferably 5 to 200. Mu.m, more preferably 10 to 100. Mu.m. When the thickness is 5 μm or more, the strength is excellent. When the thickness is 200 μm or less, the transparency is excellent.

The wetting tension of the surface of the acrylic resin film is preferably 40mN/m or more, more preferably 50mN/m or more, and still more preferably 55mN/m or more. When the wetting tension of the surface is 40mN/m or more, the adhesiveness between the optical film of the present embodiment and other members is further improved. In order to adjust the wetting tension of the surface, the surface of the acrylic resin film may be subjected to any appropriate surface treatment. The surface treatment may be, for example, corona discharge treatment, plasma treatment, ozone blowing, ultraviolet irradiation, flame treatment, or chemical treatment. Among them, corona discharge treatment and plasma treatment are preferable.

[ (acrylic) resin film production method ]

The acrylic resin film can be formed by a known film forming method using an acrylic resin. The film forming method is, for example, a solution casting method, a melt extrusion method, a calendaring method, or a compression molding method. Among them, the solution casting method and the melt extrusion method are preferable.

The acrylic resin used for film formation can be formed by a known method. For example, a (meth) acrylic polymer, other thermoplastic polymer, additives, and the like blended according to the composition of the acrylic resin desired to be obtained are thoroughly mixed by an appropriate mixing method, thereby forming an acrylic resin. The mixing method is, for example, extrusion kneading or mixing in a solution state. The film may be formed using a commercially available acrylic resin. Commercially available acrylic resins are, for example, acrypet VH and Acrypet VRL20A (both manufactured by Mitsubishi Yang). Any suitable Mixer may be used for extrusion kneading, for example, a universal Mixer (Omni Mixer), a single screw extruder, a twin screw extruder, or a pressure kneader.

The apparatus for carrying out the solution casting method is, for example, a drum casting machine, a belt casting machine, a spin coater. The solvent used in the solution casting method is not limited as long as the acrylic resin is dissolved. The solvent is, for example: aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic hydrocarbons such as cyclohexane and decalin; esters such as ethyl acetate and butyl acetate; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.; alcohols such as methanol, ethanol, isopropanol, butanol, isobutanol, methyl cellosolve, ethyl cellosolve, and butyl cellosolve; ethers such as tetrahydrofuran and dioxane; halogenated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride, etc.; dimethylformamide; dimethyl sulfoxide. It is also possible to use 2 or more of these solvents in combination.

Examples of the melt extrusion method include a T-die method and an inflation method. The molding temperature at the time of melt extrusion is preferably 150 to 350 ℃, more preferably 200 to 300 ℃. In the T-die method, for example, a tape-shaped acrylic resin film can be formed by attaching a T-die to the tip end of a known extruder. The formed belt-shaped acrylic resin film may be wound into a roll to form a film roll.

The resulting acrylic resin film may be stretched. The stretching direction may be any one of a longitudinal direction (MD direction) of the acrylic resin film, a width direction (TD direction) orthogonal to the longitudinal direction, and an oblique direction with respect to the longitudinal direction. In the case of stretching in the biaxial direction, stretching in the MD direction (longitudinal stretching) and stretching in the TD direction (transverse stretching) may be sequentially performed, or stretching in the MD direction and stretching in the TD direction may be simultaneously performed. When the glass transition temperature of the acrylic resin film is Tg, the temperature at the time of stretching is preferably in the range of (Tg-30) to (Tg+100) DEG C, more preferably in the range of (Tg-20) to (Tg+80) DEG C, and still more preferably in the range of (Tg-5) to (Tg+20) DEG C. The stretching ratio is not particularly limited, and may be, for example, about 1.1 to 25 times (for example, 1.3 to 10 times) as large as the stretching ratio defined by the area ratio. The stretching speed (one direction) is not particularly limited, and may be, for example, about 10 to 20000%/min (for example, 100 to 10000%/min). The stretched acrylic resin film is suitable as a retardation film. The stretching method is not particularly limited, and a known stretching machine can be used for stretching. The description of the stretching machine is as follows.

In the case of forming an acrylic resin film by melt extrusion, formation/stretching from formation of an acrylic resin by material-based mixing to formation/stretching of an acrylic resin film may be continuously performed. In the case of forming an acrylic resin film by the T-die method, the temperature of a roll for winding the formed film may be adjusted, and unidirectional stretching in the MD direction and winding of the film may be performed at the same time.

For example, after stretching, the acrylic resin film may be subjected to heat treatment (annealing) in order to stabilize the optical isotropy and mechanical properties of the acrylic resin film. The method and conditions of the heat treatment may be appropriately selected.

[ easy adhesive layer ]

The easy-to-adhere layer contains a binder resin, a polyamine, and fine particles. Polyamines are polymers having more than 2 amino groups. The 2 or more amino groups include at least 1 selected from the group consisting of secondary amino groups and tertiary amino groups. The polyamine content in the adhesive layer is 0.0090 to 1.4100 wt%. The polyamine promotes the dispersion of the fine particles in the easy-to-adhere layer, and improves the adhesion between the resin film and the easy-to-adhere layer, the blocking resistance of the optical film, and the uniformity of the easy-to-adhere layer.

The physical properties required for the optical film include retardation, tear resistance, folding resistance, and the like. In order to obtain a biaxially stretched optical film satisfying the required physical properties, the stretching temperature needs to be strictly controlled. The stretching temperature varies depending on subtle differences in physical properties of each batch of the resin, for example, molecular weight, composition ratio, and the like. In the production of the optical film, the drying of the adhesive layer is often performed simultaneously with the lateral stretching step. Therefore, changing the stretching temperature means changing the drying temperature of the easy-to-adhere layer. When the alkali component contained in the easy-to-adhere layer is a low molecular weight compound, the amount of the alkali component volatilized changes and the content of the alkali component in the easy-to-adhere layer also changes when the drying temperature of the easy-to-adhere layer is changed. In this case, the desired effect due to the alkali component may not be sufficiently obtained. It is difficult to change the stretching temperature in order to control the content of the alkali component within a desired range. In particular, when an optical film is produced using a resin having a high Tg such as an acrylic resin having a ring structure, it is necessary to raise the stretching temperature. The alkali component having a low molecular weight and high volatility is easily released to the outside in the stretching step at a high temperature. In this case, the effect of promoting the dispersion of fine particles by the alkali component becomes insufficient.

On the other hand, the polyamine of the polymer is less volatile and can be reliably left in the adhesive layer. Even if the stretching temperature is changed, the polyamine content in the adhesive layer is not easily changed. Therefore, the polyamine of the polymer is suitable for controlling the content of the alkali component in the easy-to-adhere layer to a desired range, and the dispersion of the fine particles can be reliably promoted. As a result, further improvement in blocking resistance of the optical film can be expected.

In addition, it is also presumed that the cationic nature of polyamine acts on the ester moiety of the acrylic resin. Namely, it is presumed that: the adhesion between the adhesive layer and the resin film is improved by the interaction between the amino group of the polyamine and the ester moiety of the acrylic resin.

In addition, when an acrylic resin having a ring structure in the main chain is used as a material of the resin film, the stretching temperature of the resin film (≡the drying temperature of the easy-to-adhere layer) is set high. The binder resin of the easy-to-adhere layer is considered to easily penetrate to the surface of the resin film which becomes a temperature higher than Tg. As a result, the adhesion between the adhesive layer and the resin film can be further improved.

The binder resin may be any known resin having an easy adhesiveness, and examples thereof include polyurethane resin, cellulose resin, polyol resin, polycarboxylic acid resin, polyester resin, and acrylic resin. At least 1 selected from these resins may be used as the binder resin.

The number average molecular weight of the binder resin is preferably 0.5 to 60 tens of thousands, more preferably 1 to 40 tens of thousands.

The binder resin includes, for example, a polyurethane resin. The binder resin is preferably a polyurethane resin. In this way, the adhesion of the easy-to-adhere layer to the acrylic resin film is improved, and the easy-to-adhere property of the optical film to other members is improved.

The polyurethane resin is not particularly limited, and is typically a resin obtained by reacting a polyol with a polyisocyanate. The polyol may be any polyol having 2 or more hydroxyl groups in the molecule. The polyol is, for example, a polyacrylic polyol, a polyester polyol, a polyether polyol. More than 2 kinds of polyols may be combined.

The polyacrylic polyol is typically a copolymer of a (meth) acrylate monomer and a monomer having a hydroxyl group. The (meth) acrylate monomer is, for example, methyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate. Examples of the monomer having a hydroxyl group include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 2-hydroxypentanyl (meth) acrylate; (meth) acrylic acid monoesters of polyhydric alcohols such as glycerin and trimethylolpropane; n-methylol (meth) acrylamides.

The polyacrylic polyol may be a copolymer with other monomers. The other monomer is not limited as long as it can be copolymerized with the (meth) acrylate monomer and the monomer having a hydroxyl group. The other monomers are, for example: unsaturated monocarboxylic acids such as (meth) acrylic acid; unsaturated dicarboxylic acids such as maleic acid, anhydrides thereof, and monoesters or diesters thereof; unsaturated nitriles such as (meth) acrylonitrile; unsaturated amides such as (meth) acrylamide and N-methylol (meth) acrylamide; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as methyl vinyl ether; alpha-olefins such as ethylene and propylene; halogenated alpha, beta-unsaturated aliphatic monomers such as vinyl chloride and vinylidene chloride; and alpha, beta-unsaturated aromatic monomers such as styrene and alpha-methylstyrene.

Polyester polyols are typically obtained by the reaction of a polyacid component with a polyol component. Examples of the polybasic acid component include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, 1, 4-naphthalene dicarboxylic acid, 2, 5-naphthalene dicarboxylic acid, 2, 6-naphthalene dicarboxylic acid, biphenyl dicarboxylic acid, and tetrahydrophthalic acid; aliphatic dicarboxylic acids such as oxalic acid, succinic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, octadecanedicarboxylic acid, tartaric acid, alkylsuccinic acid, linolenic acid, maleic acid, fumaric acid, mesaconic acid, citraconic acid, and itaconic acid; alicyclic dicarboxylic acids such as hexahydrophthalic acid, tetrahydrophthalic acid, 1, 3-cyclohexanedicarboxylic acid, and 1, 4-cyclohexanedicarboxylic acid; or reactive derivatives thereof such as acid anhydrides, alkyl esters, acid halides, and the like.

Examples of the polyhydric alcohol component include ethylene glycol, 1, 2-propylene glycol, 1, 3-butylene glycol, 1, 4-butylene glycol, neopentyl glycol, pentanediol, 1, 6-hexanediol, 1, 8-octanediol, 1, 10-decanediol, 1-methyl-1, 3-butanediol, 2-methyl-1, 3-butanediol, 1-methyl-1, 4-pentanediol, 2-methyl-1, 4-pentanediol, 1, 2-dimethyl-neopentyl glycol, 2, 3-dimethyl-neopentyl glycol, 1-methyl-1, 5-pentanediol, 2-methyl-1, 5-pentanediol, 3-methyl-1, 5-pentanediol, 1, 2-dimethylbutanediol, 1, 3-dimethylbutanol, 2, 3-dimethylbutanol, 1, 4-dimethylbutanol, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, 1, 4-cyclohexanedimethanol, 1, 4-cyclohexanediol, bisphenol A, bisphenol F, hydrogenated bisphenol A, and hydrogenated bisphenol F.

Polyether polyols are typically obtained by ring-opening polymerization of alkylene oxides and addition to polyols. The polyhydric alcohol is, for example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerol, trimethylolpropane. Alkylene oxides are, for example, ethylene oxide, propylene oxide, butylene oxide, styrene oxide, tetrahydrofuran.

Polyisocyanates are, for example: aliphatic diisocyanates such as tetramethylene diisocyanate, dodecamethylene diisocyanate, 1, 4-butane diisocyanate, hexamethylene diisocyanate, 2, 4-trimethylhexamethylene diisocyanate, 2, 4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2-methylpentane-1, 5-diisocyanate, 3-methylpentane-1, 5-diisocyanate and the like; alicyclic diisocyanates such as isophorone diisocyanate, hydrogenated xylylene diisocyanate, 4' -cyclohexylmethane diisocyanate, 1, 4-cyclohexane diisocyanate, methylcyclohexylene diisocyanate, and 1, 3-bis (isocyanatomethyl) cyclohexane; aromatic diisocyanates such as toluene diisocyanate, 2' -diphenylmethane diisocyanate, 2,4' -diphenylmethane diisocyanate, 4' -dibenzyl diisocyanate, 1, 5-naphthalene diisocyanate, xylylene diisocyanate, 1, 3-xylylene diisocyanate, and 1, 4-xylylene diisocyanate; aromatic aliphatic diisocyanates such as dialkyl diphenylmethane diisocyanate, tetraalkyl diphenylmethane diisocyanate, and α, α, α, α -tetramethyl xylylene diisocyanate.

The polyurethane resin preferably has a carboxyl group. By having a carboxyl group, the performance (adhesiveness) of the easy-to-adhere layer is improved. The effect is particularly remarkable in a high-temperature and high-humidity environment. The polyurethane resin having a carboxyl group is obtained, for example, by reacting a polyol and a polyisocyanate with a chain extender having a free carboxyl group. Chain extenders having free carboxyl groups are, for example, dihydroxycarboxylic acids and dihydroxysuccinic acids. Examples of the dihydroxycarboxylic acid include dialkanol alkanoic acids such as dimethylol alkanoic acids (e.g., dimethylol acetic acid, dimethylol butyric acid, dimethylol propionic acid, dimethylol butyric acid, and dimethylol valeric acid).

The acid value of the urethane resin is preferably 10 or more, more preferably 10 to 50, particularly preferably 20 to 45. In these cases, the performance of the adhesive layer (e.g., the adhesion to other functional films such as polarizing elements) is further improved.

The polyurethane resin can be obtained by reacting with other polyols or other chain extenders in addition to the above components. Examples of the other polyols include polyols having 3 or more hydroxyl groups such as sorbitol, 1,2,3, 6-hexyltetraol, 1, 4-sorbitan, 1,2, 4-butanetriol, 1,2, 5-pentanetriol, glycerol, trimethylolethane, trimethylolpropane, pentaerythritol and the like. Other chain extenders are, for example: glycols such as ethylene glycol, diethylene glycol, triethylene glycol, 1, 3-propanediol, 1, 3-butanediol, 1, 4-butanediol, neopentyl glycol, pentanediol, 1, 6-hexanediol, and propylene glycol; aliphatic diamines such as ethylenediamine, propylenediamine, hexamethylenediamine, 1, 4-butanediamine, and aminoethylethanolamine; alicyclic diamines such as isophorone diamine and 4,4' -dicyclohexylmethane diamine; aromatic diamines such as xylylenediamine and toluenediamine.

The polyurethane resin can be formed by a known method. The method is, for example, a one-step method in which each component is reacted at one time, a multistage method in which each component is reacted stepwise. The polyurethane resin having a carboxyl group is preferably formed by a multi-step method from the viewpoint of easy introduction of the carboxyl group. The catalyst used for forming the polyurethane resin is not particularly limited.

The polyamine may contain primary, secondary and tertiary amino groups. Such a polyamine also has an effect of improving the adhesion between the resin film and the adhesive layer.

The polyamine may comprise a polyalkyleneimine. The polyalkyleneimine is suitable as an alkali component of the easy-to-adhere layer. The polyalkyleneimine may be linear or branched.

The polyamine is preferably a polyalkylene imine. Examples of the polyalkyleneimines include polyalkyleneimines obtained by polymerizing 1 or more of the alkyleneimines having 2 to 6 carbon atoms, and derivatives obtained by adding an unsaturated carboxylic acid or an alkylene oxide to the polyalkyleneimines. Examples of the alkylene imine having 2 to 6 carbon atoms include: ethyleneimine, propyleneimine, 1, 2-butyleneimine, 2, 3-butyleneimine, 1-dimethylethyleneimine, and the like. The polyalkyleneimines are preferably polyethyleneimine, polypropyleneimine, polyethyleneimine derivatives, and polypropyleneimine derivatives, and more preferably polyethyleneimine and polyethyleneimine derivatives. Examples of the polyethyleneimine and polyethyleneimine derivative include EPOMIN series manufactured by japan catalyst, commercially available from co; EPOMIN SP-003, EPOMIN SP-006, EPOMIN SP-012, EPOMIN SP-018, EPOMIN SP-103, EPOMIN SP-110, EPOMIN SP-200, EPOMIN SP-300, EPOMIN SP-1000, EPOMIN SP-1020 (all trade names), etc.

The polyalkyleneimines may contain primary, secondary and tertiary amino groups and have a branched structure. The polyalkyleneimine having such a structure is suitable as an alkali component of the easy-to-adhere layer.

By adjusting the polyamine content in the easy-to-adhere layer to the above range, the adhesion between the resin film and the easy-to-adhere layer can be improved. The polyamine content in the easy-to-adhere layer may be 0.0098 wt% to 1.4098 wt%.

The presence and content of polyamine in the adhesive layer can be examined by a known analysis method such as NMR.

The fine particles may be any of inorganic fine particles and organic fine particles. The inorganic fine particles are, for example: inorganic oxides such as silica, titania, alumina, and zirconia; particles of calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, calcium phosphate, and the like. The organic fine particles are fine particles of, for example, silicone resin, fluorine resin, and acrylic resin. Among them, silica fine particles are preferable. The silica particles provide improved blocking resistance. Further, since the silica fine particles are excellent in transparency, the optical film is less likely to be colored and the haze ratio is less likely to increase.

The particle diameter (average particle diameter) of the fine particles is preferably 10 to 1000nm. By using fine particles having such a particle diameter, appropriate irregularities are formed on the surface of the easy-to-adhere layer, and adhesion between the acrylic resin film and the easy-to-adhere layer or between the easy-to-adhere layers can be effectively reduced. The smaller the average particle diameter of the fine particles is, the better the smaller the wavelength of visible light is, from the viewpoint of suppressing light scattering by the particles, but the larger the average particle diameter is, from the viewpoint of blocking property. Therefore, the upper limit of the average particle diameter is, for example, 900nm or less, 800nm or less, 700nm or less, 600nm or less, more preferably 500nm or less, still more preferably 400nm or less, and still more preferably 350nm or less. The lower limit is 20nm or more, 40nm or more, 60nm or more, 80nm or more, 100nm or more, more preferably 120nm or more, 140nm or more, 160nm or more, 180nm or more, 200nm or more, still more preferably 220nm or more, 240nm or more, 260nm or more, 280nm or more, 300nm or more, 320nm or more, 340nm or more in this order. The particle size distribution of the fine particles is preferably 1.0 to 1.2.

The content of the fine particles in the adhesive layer is not particularly limited, but the upper limit of the content is preferably less than 30 parts by weight, more preferably less than 20 parts by weight, and even more preferably less than 5 parts by weight, relative to 100 parts by weight of the binder resin (solid component: the solid component including the crosslinking agent in the case of containing the crosslinking agent). If the content of the fine particles is less than 30 parts by weight, the strength of the adhesive layer is excellent. The lower limit of the content is preferably 0.1 part by weight or more, more preferably 0.2 part by weight or more, and still more preferably 0.5 part by weight or more. When the content of the fine particles is 0.1 part by weight or more, the blocking resistance of the optical film is excellent. When the average particle diameter is small (for example, less than 100 nm), the content of fine particles is more preferable in order to obtain the effect of improving the blocking resistance, and the lower limit of the content is preferably 0.5 parts by weight or more, 1.0 parts by weight or more, 5.0 parts by weight or more, or 10.0 parts by weight or more. In the case where the average particle diameter is large (for example, 200nm or more), the content of fine particles is preferably small, and the upper limit of the content is preferably less than 2.0 parts by weight or less than 1.0 part by weight, from the viewpoint of suppressing light scattering.

The thickness of the adhesive layer is not limited, but is preferably 100nm to 10. Mu.m, more preferably 100nm to 5. Mu.m, still more preferably 200nm to 1.5. Mu.m, depending on the thickness of the film. Within this range, the adhesion of the adhesive layer to other members of the optical film is good. In addition, the easy-to-adhere layer itself can be suppressed from exhibiting a phase difference.

The ratio r/d of the thickness d of the easy-to-adhere layer to the average particle diameter r of the fine particles contained in the easy-to-adhere layer is preferably 0.3 to 1.4, more preferably 0.4 to 1.1, and still more preferably 0.6 to 1.0. Within this range, the blocking resistance and transparency of the optical film of the present embodiment can be more reliably combined.

The method for forming the adhesive layer on the surface of the optical film is not limited, and may be a known method. The easy-to-adhere layer is preferably formed as follows: the adhesive composition containing a binder resin, a polyamine and fine particles is applied to the surface of the resin film to form a coating film of the adhesive composition, and the coating film is dried to form the adhesive composition. The easy-to-adhere composition is preferably an aqueous composition. The aqueous composition has less burden on the environment when forming the easy-to-adhere layer than the organic solvent composition, and is excellent in handleability. The aqueous composition is, for example, a dispersion of a binder resin. The dispersion is typically an emulsion of the binder resin. The emulsion of the binder resin becomes a resin layer by drying. The fine particles contained in the emulsion directly remain in the resin layer.

When the adhesive composition is aqueous, the fine particles are preferably mixed in the form of an aqueous dispersion such as colloidal silica. The colloidal silica may be commercially available as long as the average particle diameter and the particle size distribution satisfy the above ranges.

When the easy-to-adhere composition is an aqueous composition containing a polyurethane resin, an organic solvent which is inactive to polyisocyanate and compatible with water is preferably used in forming the polyurethane resin. The organic solvents are, for example: ester solvents such as ethyl acetate, butyl acetate, and ethyl cellosolve; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ether solvents such as dioxane, tetrahydrofuran, and propylene glycol monomethyl ether.

When the easy-to-adhere composition contains a polyurethane resin, the performance of the easy-to-adhere layer is improved if the composition further contains a crosslinking agent. The crosslinking agent is not particularly limited. In the case where the polyurethane resin has a carboxyl group, the crosslinking agent is preferably a polymer having a group capable of reacting with the carboxyl group. Examples of the group capable of reacting with the carboxyl group include an organic amino group, an oxazoline group, an epoxy group and a carbodiimide group, and an oxazoline group is preferable. The oxazoline group-containing crosslinking agent has a long pot life at room temperature when mixed with the polyurethane resin, and is carried out by a heat crosslinking reaction, and therefore has good handleability. Examples of the polymer include (meth) acrylic polymers and styrene-acrylic polymers, and (meth) acrylic polymers are preferable. When the crosslinking agent is a (meth) acrylic polymer, the performance of the adhesive layer is further improved. In addition, the (meth) acrylic polymer is stably compatible with the aqueous easy-to-adhere composition, and the polyurethane resin is favorably crosslinked.

When the adhesive composition contains a polyurethane resin, the content of the polyurethane resin is preferably 1.5 to 15% by weight, more preferably 2 to 10% by weight. When the content is within these ranges, the coating property is high when the adhesive composition is applied to the surface of an optical film, particularly an acrylic resin film. When the composition further contains a crosslinking agent, the content of the crosslinking agent is preferably 1 to 30 parts by weight, more preferably 3 to 20 parts by weight, based on 100 parts by weight of the polyurethane resin (solid content).

In the case where the easy-to-adhere composition contains a polyurethane resin, it is preferable to contain a neutralizing agent. In this case, the stability of the polyurethane resin in the adhesive composition is improved. Examples of neutralizing agents are ammonia, N-methylmorpholine, triethylamine, dimethylethanolamine, methyldiethanolamine, triethanolamine, morpholine, tripropylamine, ethanolamine, triisopropanolamine, 2-amino-2-methyl-1-propanol.

The easy-to-adhere composition may contain additives. Additives are, for example, dispersion stabilizers, thixotropic agents, antioxidants, ultraviolet absorbers, defoamers, thickeners, dispersants, surfactants, catalysts, antistatics.

[ Properties and uses of optical film ]

The optical film of the present embodiment is excellent in adhesion to other members and blocking resistance. In addition, the transparency is also excellent, and the haze ratio is generally 1.5% or less. According to the configuration of the optical film of the present embodiment, the haze ratio is 1.0% or less, and further 0.5% or less.

The optical film of the present embodiment is, for example, a polarizing element protective film, a phase difference film, a viewing angle compensation film, a light diffusion film, a reflection film, an antireflection film, an antiglare film, a brightness enhancement film, or a conductive film for a touch panel. The retardation exhibited by the optical film of the present embodiment can be controlled by the composition and stretching state of the film. The optical film of the present embodiment may be an optically isotropic film or a film having optical anisotropy (for example, exhibiting birefringence such as retardation).

When the optical film of the present embodiment is used as a retardation film, the film is suitably used for an image display device such as an LCD. The retardation film can be used for color tone compensation and viewing angle compensation of an LCD, for example.

Since the retardation film has an easily adhesive layer, the retardation film may be used in a manner other than that generally used for retardation films. Specifically, for example, a mode of bonding with a polarizing element provided in an LCD can be considered. In this case, the retardation film has both a function as a normal retardation film for color tone compensation or viewing angle compensation and a function as a polarizing element protective film for protecting the polarizing element. This embodiment can eliminate a polarizing element protective film having no retardation, which has been conventionally used separately from a retardation film, and is therefore advantageous for the reduction in thickness and the improvement in functionality of an LCD.

In the case where the easy-to-adhere layer is formed on only one surface of the optical film, various functional coatings may be formed on the surface on the opposite side as needed. Examples of the functional coating layer include an antistatic layer, an adhesive layer, an easy-to-adhere layer, an antiglare (non-glare) layer, an antifouling layer such as a photocatalyst layer, an antireflection layer, a hard coat layer, an ultraviolet ray shielding layer, a heat ray shielding layer, an electromagnetic wave shielding layer, and a gas barrier layer.

[ optical Member ]

The optical film of the present embodiment is suitable for an optical member such as a polarizing plate, a diffusion plate, a light guide, or a prism sheet, for example.

As an example of the optical member of the present embodiment, a polarizing plate will be described. In an LCD, a pair of polarizing plates are arranged so as to sandwich a liquid crystal cell based on the image display principle thereof. The polarizing plate has a structure in which an optical film (polarizing element protective film) according to the present embodiment is laminated on at least one surface of a polarizing element via an easy-to-adhere layer, for example.

Conventionally, a triacetyl cellulose (TAC) film has been used as a protective film for a polarizing element. However, the wet heat resistance of the TAC film is insufficient, and when the TAC film is used as a protective film for a polarizing element, the characteristics of the polarizing plate may deteriorate under high temperature or high humidity conditions. The TAC film has a phase difference in the thickness direction, and this phase difference adversely affects viewing angle characteristics of an image display device such as an LCD, particularly an image display device with a large screen. In contrast, when an acrylic resin film is used for the polarizing element protective film, the wet heat resistance and optical characteristics can be improved as compared with those of the TAC film, which is preferable.

Typically, a polarizing plate is manufactured by laminating an optical film and a polarizing element via an adhesive layer. When the optical film has an easy-to-adhere layer, the two layers are laminated so that the easy-to-adhere layer is on the polarizing element side. Specifically, for example, an adhesive composition that becomes an adhesive layer after drying is applied to a surface of one selected from the polarizing element and the optical film, and then both are bonded and dried. The adhesive composition may be applied by, for example, a roll method, a spray method, or an immersion method. When the adhesive composition contains a metal compound colloid, the adhesive composition is applied such that the thickness of the dried adhesive layer is larger than the average particle diameter of the metal compound colloid particles. The drying temperature is typically 5 to 150℃and preferably 30 to 120 ℃. The drying time is typically 120 seconds or more, preferably 300 seconds or more.

The polarizing element is not limited, and any appropriate polarizing element may be used according to the function required as a polarizing plate. The polarizing element is, for example, a film obtained by unidirectionally stretching a hydrophilic polymer film such as a polyvinyl alcohol (PVA) film, a partially formalized PVA film, or a partially saponified film of an ethylene-vinyl acetate copolymer (EVA) by adsorbing a dichroic material such as iodine or a dichroic dye; a multi-functional oriented film using a dehydrated PVA or a desalted polyvinyl chloride material. Among them, a film in which a dichroic material is adsorbed on a PVA-based film and uniaxially stretched is preferable as a polarizing element. The polarizing element exhibits a high polarization dichroic ratio. The thickness of the polarizing element is not limited, and is usually about 1 to 80. Mu.m. For example, a polarizing element in which iodine is adsorbed onto a PVA-based film and uniaxially stretched can be produced by immersing the PVA-based film in an aqueous solution containing iodine, dyeing the film, and uniaxially stretching the film at a stretching ratio of 3 to 7 times. The aqueous solution used for dyeing may contain boric acid, zinc sulfate, zinc chloride, and the like, as required. As the aqueous solution containing iodine, an aqueous solution of iodide such as potassium iodide can be used. The PVA-based film may be immersed in water for water washing before dyeing. The dirt, the anti-blocking agent, and the like present on the surface of the PVA-based film can be removed by washing the film with water. Further, since the PVA-based film swells by water washing, unevenness in dyeing is suppressed. Stretching may be performed before dyeing, after dyeing, or simultaneously with dyeing.

The adhesive composition to be an adhesive layer after drying is not limited. The bonding method is not limited, and may be aqueous paste or UV bonding. The adhesive composition preferably contains a PVA-based resin. The PVA-based resin contains, for example, the following polymers: saponified polyvinyl acetate and derivatives thereof; saponified products of copolymers of vinyl acetate with other monomers; modified PVA obtained by acetalization, urethanization, etherification, grafting or phosphorylation of PVA. Examples of the other monomer include unsaturated carboxylic acids such as maleic acid (anhydride), fumaric acid, crotonic acid, itaconic acid, and (meth) acrylic acid, and esters thereof; alpha-olefins such as ethylene and propylene; (meth) allylsulfonic acid (sodium), sodium sulfonate (mono alkyl malate), sodium disulfonate alkyl malate, N-methylolacrylamide, alkali metal salts of acrylamide alkyl sulfonic acid, N-vinylpyrrolidone derivatives. The PVA-based resin preferably contains PVA containing an acetoacetyl group. In this case, the adhesiveness between the polarizing element and the optical film (particularly, the acrylic resin film) is improved, and the durability of the polarizing plate is improved.

The average polymerization degree of the PVA-based resin is preferably about 100 to 5000, more preferably 1000 to 4000, from the viewpoint of the adhesiveness of the adhesive composition. The average saponification degree of the PVA-based resin is preferably about 85 to 100 mol%, more preferably 90 to 100 mol%, from the viewpoint of the adhesiveness of the adhesive composition.

The acetoacetyl group-containing PVA can be obtained, for example, by reacting PVA with diketene by any method. Specific examples are: a method of adding diketene to a dispersion obtained by dispersing PVA in a solvent such as acetic acid; a method of adding diketene to a solution obtained by dissolving PVA in a solvent such as dimethylformamide or dioxane; a method of directly contacting PVA with diketene gas or liquid diketene.

The degree of acetoacetyl modification in the acetoacetyl-containing PVA is typically 0.1 mol% or more, preferably 0.1 to 40 mol%, more preferably 1 to 20 mol%, still more preferably 2 to 7 mol%. By properly adjusting the degree of modification, the effect of modification (for example, improvement of water resistance) can be sufficiently obtained. The degree of acetoacetyl modification of PVA can be determined by NMR.

The adhesive composition may include a cross-linking agent. The crosslinking agent is not limited, and is a compound having at least 2 functional groups exhibiting reactivity to the PVA-based resin. Examples of the crosslinking agent include alkylene diamines having an alkylene group and 2 amino groups such as ethylenediamine, triethylenediamine and 1, 6-hexamethylenediamine; isocyanates such as toluene diisocyanate, hydrogenated toluene diisocyanate, trimethylolpropane toluene diisocyanate adduct, triphenylmethane triisocyanate, methylenebis (4-phenylmethane triisocyanate), isophorone diisocyanate, and ketoxime blocks or phenol blocks thereof; epoxides such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol triglycidyl ether, 1, 6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, and diglycidyl amine; monoaldehydes such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, and the like; dialdehydes such as glyoxal, malondialdehyde, succindialdehyde, glutaraldehyde, maledialdehyde, phthaldialdehyde, and the like; amino-formaldehyde resins such as methylol urea, methylol melamine, alkylated methylol urea, alkylated methylol melamine, acetoguanamine, and condensates of benzoguanamine and formaldehyde; salts and oxides of monovalent to trivalent metals such as sodium, potassium, magnesium, calcium, aluminum, iron, nickel, and the like. Among these, amino-formaldehyde resins and dialdehydes are preferred as crosslinking agents. The amino-formaldehyde resin preferably has a methylol group, with methylolmelamine being preferred. Among the dialdehydes, glyoxal is preferred.

The blending amount of the crosslinking agent in the adhesive composition can be appropriately set according to the type of PVA-based resin. Typically, the amount is about 10 to 60 parts by weight, preferably 20 to 50 parts by weight, based on 100 parts by weight of the PVA-based resin. Within this range, good adhesion can be obtained. By properly adjusting the mixing amount of the crosslinking agent, gelation of the adhesive composition can be suppressed. In this case, the usable time (pot life) of the adhesive composition is prolonged, and industrial use is facilitated.

The adhesive composition may comprise a metal compound colloid. The metal compound colloid may be a colloid in which particles of the metal compound are dispersed in a dispersion medium. The metal compound colloid can be a colloid having long-lasting stability due to electrostatic stabilization by mutual repulsion of the same charges of particles. By including the metal compound colloid in the adhesive composition, for example, even when the amount of the crosslinking agent to be mixed is large, the stability of the adhesive composition is improved.

The average particle diameter of the colloidal particles in the metal compound colloid may be set within a range that does not adversely affect the optical characteristics (e.g., polarized light characteristics) of the polarizing plate. The average particle diameter of the colloidal particles is preferably 1 to 100nm, more preferably 1 to 50nm. In this range, the colloidal particles can be uniformly dispersed in the adhesive layer. This ensures adhesion and suppresses occurrence of kink (kineck) defects. If kink defects occur, light leakage occurs in, for example, an image display device incorporating the polarizing plate.

The metal compound is not limited, and is, for example, an oxide such as alumina, silica, zirconia, or titania; metal salts such as aluminum silicate, calcium carbonate, magnesium silicate, zinc carbonate, barium carbonate, and calcium phosphate; diatomaceous earth, talc, clay, kaolin, and other minerals. Metal compound colloids having positive charges are preferred. The metal compound to be a colloid having a positive charge is preferably alumina or titania, and particularly preferably alumina.

The metal compound colloid is typically a colloidal solution dispersed in a dispersion medium. The dispersion medium is, for example, water or alcohol. The concentration of the solid content in the colloidal solution is typically about 1 to 50% by weight, preferably 1 to 30% by weight. The colloidal solution may contain an acid such as nitric acid, hydrochloric acid, acetic acid, or the like as a stabilizer.

The amount of the metal compound colloid to be blended (in terms of solid content) in the adhesive composition is preferably 200 parts by weight or less, more preferably 10 to 200 parts by weight, still more preferably 20 to 175 parts by weight, and particularly preferably 30 to 150 parts by weight, based on 100 parts by weight of the PVA-based resin. Within these ranges, the adhesiveness of the adhesive composition becomes more reliable, and the occurrence of kink defects is further suppressed.

The adhesive composition may contain a coupling agent such as a silane coupling agent and a titanium coupling agent; various adhesion promoters; an ultraviolet absorber; an antioxidant; stabilizers such as heat stabilizer and hydrolysis-resistant stabilizer.

The adhesive composition is preferably an aqueous solution (resin solution). The concentration of the resin in the aqueous solution is preferably 0.1 to 15% by weight, more preferably 0.5 to 10% by weight, from the viewpoints of coatability and storage stability of the composition. The viscosity of the aqueous solution is preferably 1 to 50 mPas. When the adhesive composition contains a metal compound colloid, the occurrence of kink defects can be effectively suppressed even at a low viscosity of 1 to 20mpa·s. The pH of the aqueous solution is preferably 2 to 6, more preferably 2.5 to 5, still more preferably 3 to 5, particularly preferably 3.5 to 4.5. The surface charge of the metal compound colloid is generally adjusted by adjusting the pH of the aqueous solution. The surface charge is preferably a positive charge. The occurrence of kink defects can be further suppressed by being positively charged. The surface charge of the metal compound colloid can be confirmed by measuring the zeta potential using a zeta potential measuring machine, for example.

The adhesive composition as an aqueous solution (resin solution) can be formed by a known method. In the case where the adhesive composition contains the crosslinking agent and the metal compound colloid, for example, a method of mixing the metal compound colloid into a solution in which the PVA-based resin and the crosslinking agent are mixed and adjusted to have an appropriate concentration may be employed. The crosslinking agent may be mixed under the condition that the use period of the adhesive composition is taken into consideration after the PVA-based resin and the metal compound colloid are mixed. The concentration of the aqueous solution may be adjusted after the aqueous solution is prepared.

The thickness of the adhesive layer formed of the adhesive composition may be appropriately set according to the composition of the composition. The thickness is preferably 10 to 300nm, more preferably 10 to 200nm, particularly preferably 20 to 150nm. Within this range, the adhesive layer exhibits sufficient adhesive force.

[ image display device ]

The optical film of the present embodiment is suitable for an image display device such as an Electroluminescence (EL) display panel, a Plasma Display Panel (PDP), a field emission display (FED: field Emission Display), or an LCD. The configuration of the image display device including the optical film of the present embodiment is not particularly limited, and may include a power source, a backlight unit, an operation unit, and the like as appropriate as necessary.

[ method for producing optical film ]

The method for manufacturing the optical film comprises the following steps: a step (coating step) of forming a coating film of an easy-to-adhere composition containing a binder resin, a polyamine and fine particles by coating the surface of a resin film; and a step (drying step) of drying the formed coating film to form an easily adhesive layer on the surface of the resin film. The method for producing the resin film is as described above.

In the coating step, a coating film of the composition that is easy to adhere is formed on at least one surface of the resin film. Typically, the coating film is formed on one surface of the optical film. The method of applying the adhesive composition in the application step may be a known method.

Examples of the method include bar coating (roll coating), gravure coating, rod coating (rod coating), slit nozzle coating, curtain coating, and spray coating (fountain coating). The thickness of the coating film formed in the coating step may be appropriately adjusted according to the thickness required when the coating film is formed into an easy-to-adhere layer.

The surface of the resin film coated with the easy-to-adhere composition is preferably subjected to a surface treatment. The surface treatment is as described above, and corona discharge treatment and plasma treatment are preferable. The conditions of the corona discharge treatment are not limited. The electron irradiation amount in the corona discharge treatment is preferably 50 to 150W/m ² Preferably 70 to 100W/m per minute ² /min.

The drying step may be performed by a known method. The drying temperature is typically 50 ℃ or higher, preferably 90 ℃ or higher, more preferably 110 ℃ or higher. By setting the drying temperature in these ranges, an optical film excellent in corrosion resistance (particularly in a high-temperature and high-humidity environment) is obtained, for example. The upper limit of the drying temperature is preferably 200℃or less, more preferably 180℃or less.

The resin film may be stretched between the coating step and the drying step, simultaneously with the drying step, or after the drying step. The stretching of the resin film after the application of the easy-to-adhere composition may be performed by a known method, and may be performed in a unidirectional or bidirectional manner in the same manner as the stretching method of the resin film (before the application of the easy-to-adhere layer).

The resin film forming the coating film of the composition that is easy to adhere in the coating step may be an unstretched resin film or a stretched resin film. When the resin film before the coating step is an unstretched film and the optical film to be finally produced is a biaxially oriented film, biaxially oriented film may be performed after the coating step. When the resin film before the coating step is a uniaxially stretched film and the optical film to be finally produced is a biaxially stretched film, the direction of the uniaxially stretching is set to the MD direction, and the film is stretched in the TD direction after the coating step.

The stretching of the resin film may be performed using a known stretching machine. The longitudinal stretching machine is not particularly limited, and an oven stretching machine is preferable. The oven longitudinal stretcher is generally composed of an oven and conveying rollers provided at an inlet side and an outlet side of the oven, respectively. By imparting a peripheral speed difference between the conveying roller on the inlet side and the conveying roller on the outlet side of the oven, the resin film is stretched in the conveying direction. The transverse stretching machine is not particularly limited, and a tenter stretching machine is preferable. The tenter stretcher may be a clamp type or a pin plate type, but is preferably a clamp type because tearing of the resin film is less likely to occur. The clamp type tenter stretcher is generally composed of a clamp operating device for transverse stretching and an oven. In the clamp operation device, the resin film is conveyed in a state that the lateral end portion of the resin film is clamped by the clamp. At this time, the resin film is stretched in the lateral direction by widening the distance between the left and right 2 rows of grippers by opening the guide rail of the gripper operation device. In the clip type tenter, the clip can also simultaneously perform biaxial stretching by having an expansion/contraction function with respect to the conveying direction of the resin film. In addition, the inclined stretcher may be: the resin film is drawn and stretched in the film conveyance direction at different speeds in the stretching direction.

The stretching temperature is preferably around Tg of the resin constituting the resin film. Specifically, it is preferably in the range of Tg-30℃to Tg+100℃, more preferably in the range of Tg-20℃to Tg+80℃. By properly adjusting the stretching temperature, a sufficient stretching ratio can be stably achieved.

The stretch ratio defined in terms of area ratio is preferably 1.1 to 25 times, more preferably 1.3 to 10 times. By appropriately adjusting the stretching ratio, the characteristics (e.g., toughness) of the optical film can be improved. The stretching speed is preferably 10 to 20000%/min, more preferably 100 to 10000%/min, in one direction of stretching. By properly adjusting the stretching speed, breakage of the optical film can be prevented, and the time required for stretching can be shortened.

In the case where the formation of the easy-to-adhere layer and the stretching of the resin film are performed simultaneously, for example, the resin film on which the coating film of the easy-to-adhere composition is formed may be stretched in a heated atmosphere after the coating step. The adhesive layer is formed by drying a coating film of the adhesive composition formed on the surface of the resin film by heat applied to the resin film for stretching. Since the Tg of the resin film is usually 100 ℃ or higher, the stretching temperature is a temperature high enough for forming the easy-to-adhere layer from the coating film of the easy-to-adhere composition.

In the case of forming a resin film by melt extrusion, the steps from the formation of the resin film to the obtaining of an optical film as a stretched film may be continuously performed. In this case, it is preferable that the step of applying the adhesive composition to the surface of the resin film and the step of stretching the film coated with the adhesive composition under a heated atmosphere are performed continuously. The coating step of the adhesive composition continuously performed in this way is called in-line (inline) coating. In the case of producing an optical film as a biaxially stretched film by the production method of the present embodiment, it is particularly preferable to continuously perform a process of stretching an unstretched film to obtain a film as a biaxially stretched film, a process of applying an easy-to-adhere composition to the surface of the film, and a process of stretching the film coated with the easy-to-adhere composition under a heated atmosphere. Further, in the case of subjecting the film to surface treatment such as corona discharge treatment and plasma treatment, it is preferable that the process of stretching an unstretched film to obtain a film as a unidirectional stretched film, the process of subjecting the surface of the film to surface treatment, the process of applying the composition for easy adhesion to the surface of the film after surface treatment, and the process of stretching the film coated with the composition for easy adhesion under a heating atmosphere are continuously performed.

The manufacturing method of the present embodiment may include any steps other than the above steps. This step is, for example, a step of laminating an additional layer (for example, a resin layer) on the formed optical film, or a step of applying a post-treatment such as a coating treatment or a surface treatment to the formed optical film.

Examples

The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to the following examples.

(1) Analysis method

(1-1) weight average molecular weight (Mw)

The weight average molecular weight was determined by polystyrene conversion using Gel Permeation Chromatography (GPC). The apparatus used for the measurement and the measurement conditions are as follows.

-a system: GPC System HLC-8220 manufactured by Tosoh corporation

-measuring jamb formation

Protective column: manufactured by Tosoh Co., ltd., TSKguardcolumn SuperHZ-L

Separation column: TSKgel SuperHZM-M2 root series connection manufactured by Tosoh Corp

Reference jamb formation

Reference column: TSKgel SuperH-RC manufactured by Tosoh Corp

-developing solvent: chloroform (Special grade manufactured by Heguang pure medicine industry Co., ltd.)

Flow rate of developing solvent: 0.6 mL/min

Standard sample: TSK standard polystyrene (PS-oligomer kit manufactured by Tosoh Corp.)

Column temperature: 40 DEG C

(1-2) glass transition temperature (Tg)

The glass transition temperature was determined in accordance with the regulation of JIS K7121. Specifically, about 10mg of the sample was heated from room temperature to 200℃under a nitrogen atmosphere using a differential scanning calorimeter (manufactured by Rigaku corporation, thermo plus EVO DSC-8230), and the obtained DSC curve was evaluated by a starting point method. The reference used was alpha-alumina.

(1-3) thickness of optical film

The thickness of the optical film was measured using a digital micrometer (manufactured by Mitutoyo corporation). The sample for measuring and evaluating the physical properties of the optical film (including the physical properties of the evaluation method described below) was obtained from the center portion in the width direction of the film.

(1-4) average particle diameter and particle size distribution of the microparticles

The silica particles were placed in methanol so as to have a concentration of 1 mass%, and the silica particles were dispersed for 10 minutes by an ultrasonic disperser to prepare a measurement sample. The sample was measured using a laser diffraction/scattering particle size distribution measuring apparatus (LA-920, manufactured by horiba corporation). The arithmetic average value of the obtained volume-based particle size distribution was used as the average particle size, and the arithmetic maximum value was used as the maximum particle size.

(1-5) Total light transmittance, haze

The total light transmittance, haze (total haze) and internal haze of the produced optical film were measured by using a haze meter (manufactured by japan electric color industry, NDH 5000) in accordance with the specifications of JIS K7136. The internal haze was measured in a state where a film as an object to be measured was immersed in tetralin in a quartz cell.

(1-6) adhesion of resin film to adhesive layer

The adhesion between the produced resin film and the adhesive layer was evaluated by the following procedure, by performing a checkerboard test in accordance with JIS K5400.3.5. At 3 of the easy-to-adhere layer of the test specimen, a 1mm square checkered cut was made with a sharp knife. A scotch tape (24 mm wide, JIS Z1522) was adhered to the slit with a wooden spatula. Then, the transparent adhesive tape was peeled off, and whether or not the easy-to-adhere layer was peeled off was confirmed. When the adhesive layer was not peeled off, a new scotch tape was adhered to the incision with a wood blade again, and the scotch tape was peeled off to evaluate the adhesion. The evaluation was performed at 3. The evaluation criteria are as follows.

And (3) the following materials: at 3 out of 3, the easy-to-adhere layer was not peeled off even if 5 peeling tests were performed.

O: at 1 or 2 of the 3 s, the easy-to-adhere layer was not peeled off even if the peeling test was performed 5 times.

X: at 3 of the 3 parts, the adhesive layer was easily peeled off in 1 to 4 peeling tests.

(1-7) blocking resistance of optical films

The blocking resistance of the produced optical film was evaluated as follows. The optical film thus produced was wound into a roll to form a film roll, and then left to stand for 24 hours. After the placement, the film roll was visually confirmed, and the surface was visually confirmed in the entire length direction of the optical film while the optical film was paid out from the film roll, and the blocking resistance was evaluated. The evaluation criteria are as follows.

O: deformation of the film roll and wrinkles of the released optical film were not confirmed.

X: deformation of the film roll or wrinkles of the released optical film were confirmed.

(1-8) uniformity of easy-to-bond layer

The prepared easy-to-adhere composition (coating liquid) was applied to a resin film and dried, and the obtained easy-to-adhere layer (coating film) was visually observed to evaluate the uniformity of the easy-to-adhere composition and the uniformity of the easy-to-adhere layer. The evaluation criteria are shown as (evaluation of the adhesive composition)/(evaluation of the adhesive layer) below.

With respect to the evaluation of the easy-to-adhere composition,

a: it is easy to obtain a uniform composition which is easy to adhere.

B: non-uniform substances such as gel components are observed when the easy-to-adhere composition is produced, but a uniform easy-to-adhere composition can be obtained only by stirring for less than 6 hours.

C: non-uniform substances such as gel components are observed when the easy-to-adhere composition is produced, but a uniform easy-to-adhere composition cannot be obtained without filtration.

Regarding the evaluation of the easy-to-adhere layer,

a: the uneven coating, streak, and uneven thickness could not be visually confirmed, and a uniform coating film could be obtained.

B: at least 1 of uneven coating, streaking, and uneven thickness was visually confirmed, and a uniform coating film could not be obtained.

(2) Production example

Production example 1

40 parts by weight of Methyl Methacrylate (MMA), 10 parts by weight of methyl 2- (hydroxymethyl) acrylate (MHMA), 50 parts by weight of toluene as a polymerization solvent and 0.025 parts by weight of an antioxidant (manufactured by ADK STAB 2112, ADEKA) were charged into a reaction vessel having an internal volume of 1000L and provided with a stirring device, a temperature sensor, a cooling tube and a nitrogen gas introduction tube, and nitrogen gas was introduced thereinto and the temperature was raised to 105 ℃. At the beginning of the reflux accompanied by the temperature rise, 0.05 part by weight of t-amyl isononanoate (trade name: luperox 570, manufactured by ARKEMA Jifu) was added as a polymerization initiator, and 0.10 part by weight of t-amyl isononanoate was added dropwise over 3 hours, and at the same time, solution polymerization was carried out at a reflux temperature of about 105 to 110℃and further curing was carried out for 4 hours.

Next, 0.05 parts by weight of 2-ethylhexyl phosphate (manufactured by Sakai chemical industry, phoslex A-8) as a catalyst (cyclization catalyst) for the cyclized condensation reaction was added to the obtained polymerization solution, and the cyclized condensation reaction was carried out at a reflux temperature of about 90 to 110℃for 2 hours to form a lactone ring structure. Subsequently, the resulting polymerization solution was heated to 240℃with an autoclave, and a cyclized condensation reaction was further carried out at this temperature.

Next, the obtained polymerization solution was introduced into a vented twin screw extruder at a treatment rate of 45 kg/hr (resin amount conversion)L/d=30), in which devolatilization was performed, the barrel temperature was 240 ℃, the rotational speed was 100rpm, the vacuum degree was 13.3 to 400hPa (10 to 300 mmHg), the number of rear vents was 1 and the number of front vents was 4 (referred to as 1 st, 2 nd, 3 rd, 4 th vents from the upstream side), side feeders were provided between the 3 rd vent and the 4 th vent, and a leaf disc type polymer filter was arranged at the front end (filtration accuracy was 5 μm, filtration area was 1.5 m) ² ). At this time, the separately prepared mixed solution of the antioxidant/the cyclization catalyst deactivator was fed from the rear of the 1 st vent at a feed rate of 0.68 kg/hr, and the ion-exchanged water was fed from the rear of the 2 nd and 3 rd vents at a feed rate of 0.22 kg/hr, respectively. For the mixed solution of antioxidant/cyclization catalyst deactivator, use is made of 50 parts by weight of an antioxidant (manufactured by Ciba Specialty Chemicals, IRGANOX 1010) and 35 parts by weight of zinc octoate (manufactured by Nikka Octhix zinc 3.6% by weight) as a deactivator were dissolved in 200 parts by weight of toluene. In addition, pellets of a styrene-acrylonitrile copolymer (AS resin: styrene unit/acrylonitrile unit ratio: 73 wt.%/27 wt.%, weight average molecular weight: 22 ten thousand) were fed from a side feeder at a feeding rate of 15 kg/hr during devolatilization.

After the completion of the devolatilization, the resin in a hot-melt state remaining in the extruder was discharged from the front end of the extruder while being filtered by a polymer filter, and pelletized by a pelletizer to obtain transparent pellets (1A) of an acrylic resin, wherein the transparent pellets (1A) contain a (meth) acrylic polymer having a lactone ring structure in the main chain as a main component (content: 75% by weight) and further contain a styrene-acrylonitrile copolymer at a content of 25% by weight. The Tg of the acrylic resin constituting the pellet (1A) was 122℃and the weight-average molecular weight was 15.1 ten thousand.

Next, a single screw extruder is utilizedThe pellets (1A) thus produced were melt-extruded at 280℃with a coat hanger type T-die (width: 150 mm) to form an acrylic resin film having a thickness of 100. Mu.m. At the time of melt extrusion, the resin film was discharged from the T die onto a cooling roll maintained at 110 ℃.

Next, the produced acrylic resin film was subjected to free-end unidirectional stretching in the MD direction (flow direction, extrusion direction) at a stretching ratio of 2.0 times and a stretching temperature of 140 ℃ by a biaxial stretching machine (TYPE EX4, manufactured by eastern jejunum), to obtain a stretched acrylic resin film (F1).

Production example 2

42.5 parts by weight of MMA, 5 parts by weight of N-Phenylmaleimide (PMI), 0.5 part by weight of styrene (St), 50 parts by weight of toluene as a polymerization solvent, 0.2 part by weight of acetic anhydride as an organic acid, and 0.06 part by weight of N-dodecylmercaptan as a chain transfer agent were charged into a stainless steel polymerization vessel having an internal volume of 100L and provided with a submerged vessel and a stirring device, and stirred at a rotation speed of 100rpm while being purged with nitrogen for 10 minutes. Next, the temperature was raised while keeping the inside of the tank under a nitrogen atmosphere, and 0.075 parts by weight of t-butyl peroxyisopropyl carbonate was added at the point when the temperature in the tank reached 100℃and at the same time, nitrogen bubbling was started in the submerged tank. Subsequently, a mixed solution of 2 parts by weight of styrene and 0.075 parts by weight of t-butyl peroxyisopropyl carbonate was added to the tank at a constant speed over a period of 5 hours while the polymerization was carried out at a reflux temperature of 105 to 110℃for 15 hours.

Next, 0.1 parts by weight of 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (HCA, manufactured by Sanguang Co., ltd.) as a phosphoric acid antioxidant and 0.02 parts by weight of pentaerythrityl-tetrakis [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate ] (manufactured by Asahi electro-chemical Co., ltd., AO-60) as a phenol antioxidant were added to the obtained polymerization solution, respectively.

Next, the polymerization solution to which the antioxidant was added was introduced into a vented type screw twin-screw extruder (Φ=29.75 mm, L/d=30) having a barrel temperature of 240 ℃, a rotation speed of 100rpm, a vacuum of 13.3 to 400hPa (10 to 300 mmHg), a number of rear vents of 1, and a number of front vents of 4 at a processing rate of 2.0 kg/hour (resin amount conversion). Next, the resin in the hot-melt state in the extruder was discharged from the front end of the extruder, and pelletized by a pelletizer to obtain transparent pellets (2A) of the acrylic resin, the transparent pellets (2A) being composed of a (meth) acrylic polymer having an N-substituted maleimide structure in the main chain. The Tg of the acrylic resin constituting the pellet (2A) was 138℃and the weight-average molecular weight was 20.0 ten thousand.

Next, a single screw extruder is utilizedThe pellets (2A) thus produced were melt-extruded at 280℃with a coat hanger type T-die (width: 150 mm) to form an acrylic resin film having a thickness of 100. Mu.m. During melt extrusion, acrylic is used as the materialThe resin film was discharged from the T-die onto a cooling roll maintained at 110 ℃.

Next, the produced acrylic resin film was subjected to free-end unidirectional stretching in the MD direction (flow direction, extrusion direction) by a biaxial stretching machine (TYPE EX4, manufactured by eastern jejunum), at a stretching ratio of 2.0 times and a stretching temperature of 155 ℃.

Production example 3

Using single screw extruderL/d=25) and a coat hanger type T-die (150 mm wide) at 280 ℃ for an acrylic resin (Rohm) having a main chain of a (meth) acrylic polymer having a glutarimide structure as a main component&Haas, KAMAX T-240) (this resin was melt-extruded as 3A) to form an acrylic resin film having a thickness of 100. Mu.m. At the time of melt extrusion, the resin film was discharged from the T die onto a cooling roll maintained at 110 ℃.

Next, the produced acrylic resin film was subjected to free-end unidirectional stretching in the MD direction (flow direction, extrusion direction) at a stretching ratio of 2.0 times and a stretching temperature of 140 ℃ by a biaxial stretching machine (manufactured by eastern jejunum, TYPE EX 4), to obtain a stretched acrylic resin film (F3).

Production example 4

A stretched acrylic resin film (F4) was obtained in the same manner as in production example 3, except that an acrylic resin (Sumipex B-TR) comprising a (meth) acrylic polymer having a glutaric anhydride structure in the main chain as a main component was used in place of KAMAX T-240.

Production example 5

A stretched acrylic resin film (F5) was obtained in the same manner as in production example 3, except that an acrylic resin (Delpet 980N, manufactured by asahi chemical industry) containing a (meth) acrylic polymer having a maleic anhydride structure as a main chain was used instead of KAMAX T-240.

Production example 6

A reaction mixture of 70 parts by weight of deionized water, 0.5 part by weight of sodium pyrophosphate, 0.2 part by weight of potassium oleate, 0.005 part by weight of ferrous sulfate, 0.2 part by weight of dextrose, 0.1 part by weight of terpene hydroperoxide and 28 parts by weight of 1, 3-butadiene was charged into a pressure-resistant reaction vessel equipped with a stirrer, and the temperature was raised to 65℃to carry out polymerization reaction. To this mixture, 0.2 parts by weight of p-hydroperoxide was further added at a time when 2 hours passed from the start of polymerization, while 72 parts by weight of 1, 3-butadiene, 1.33 parts by weight of potassium oleate and 75 parts by weight of deionized water were continuously added dropwise over a period of 2 hours. Thereafter, the polymerization reaction was continued, and an emulsion of butadiene-based rubber polymer having an average particle diameter of 0.240 μm was obtained by polymerization for 21 hours from the start of the polymerization.

Next, 120 parts by weight of deionized water, 50 parts by weight (solid content) of the butadiene rubber polymer emulsion prepared above, 1.5 parts by weight of potassium oleate, and 0.6 parts by weight of Sodium Formaldehyde Sulfoxylate (SFS) were charged into a polymerization vessel equipped with a cooler and a stirrer, and the inside of the vessel was sufficiently replaced with nitrogen gas. Then, after the temperature in the vessel was raised to 70 ℃, a mixed monomer solution composed of 36.5 parts by weight of styrene and 13.5 parts by weight of acrylonitrile and a polymerization initiator solution composed of 0.27 parts by weight of cumene hydroperoxide and 20 parts by weight of deionized water were continuously added dropwise to the vessel over a period of 2 hours, respectively, to carry out polymerization. After the termination of the dropwise addition, the temperature in the vessel was raised to 80℃and the polymerization was further continued for 2 hours. Next, after the temperature in the vessel was lowered to 40 ℃, the content was passed through a 300 mesh wire mesh to obtain an emulsion polymerization liquid of elastic organic fine particles.

The emulsion polymerization solution of the obtained elastic organic fine particles was salted out and coagulated with calcium chloride, and the coagulated material was washed with water and dried to obtain elastic organic fine particles (G1: average particle diameter 0.260 μm, refractive index of soft polymer layer 1.516) in the form of powder.

Next, an acrylic resin (Delpet 980N manufactured by Asahi chemical Co., ltd.) containing a (meth) acrylic polymer having a maleic anhydride structure as a main component in its main chain and the elastic organic fine particles (G1) produced as described above were kneaded by a twin screw extruderThe acrylic resin/elastic organic fine particles=90/10 (weight ratio) was used to prepare pellets (3A). Next, a single screw extruder is utilizedThe pellets (3A) thus produced were melt-extruded at 280℃with a coat hanger type T-die (width: 150 mm) to form an acrylic resin film having a thickness of 100. Mu.m. At the time of melt extrusion, the resin film was discharged from the T die onto a cooling roll maintained at 110 ℃.

Next, the produced acrylic resin film was subjected to free-end unidirectional stretching in the MD direction (flow direction, extrusion direction) by a biaxial stretching machine (TYPE EX4, manufactured by eastern jejunum), at a stretching ratio of 2.0 times and a stretching temperature of 140 ℃.

Production example 7

229.6 parts by weight of Methyl Methacrylate (MMA), 33 parts by weight of methyl 2- (hydroxymethyl) acrylate (MHMA), 0.138 part by weight of antioxidant (ADK STAB (registered trademark) 2112 manufactured by ADEKA corporation), 248.6 parts by weight of toluene as a non-polymerizable organic solvent, and 0.1925 parts by weight of n-dodecyl mercaptan were charged into a reaction vessel provided with a stirring device, a temperature sensor, a cooling tube, and a nitrogen gas was introduced thereinto, and the temperature was raised to 105 ℃. At the beginning of the reflux accompanied by the temperature rise, 0.2838 parts by weight of t-amyl isononanoate (manufactured by ARKEMA Jifu Co., ltd. "Luperox (registered trademark)") as a polymerization initiator was added, and 0.5646 parts by weight of t-amyl isononanoate and 12.375 parts by weight of styrene (St) were added dropwise over 2 hours, while solution polymerization was carried out at a reflux of about 105 to 110℃and after the completion of the addition, further curing was carried out at the same temperature for 4 hours.

Next, 0.206 parts by weight of stearyl phosphate (Phoslex A-18, manufactured by Saikovia chemical Co., ltd.) as a catalyst (cyclization catalyst) for the cyclized condensation reaction was added to the obtained polymerization solution, and the cyclized condensation reaction was carried out at a reflux temperature of about 90 to 110℃for 2 hours to form a lactone ring structure. Then, after the cyclized condensation reaction of the obtained polymerization solution was completed by passing through a multitube heat exchanger heated to 240 ℃, the polymerization solution was introduced into a vented screw twin-screw extruder (L/d=52) having a barrel temperature of 250 ℃ and having 1 rear vent and 4 front vents (referred to as the 1 st, 2 nd, 3 rd and 4 th vents from the upstream side), and having a side feeder between the 3 rd vent and the 4 th vent, and a polymer filter (having a filtration accuracy of 5 μm) having a leaf disk type disposed at the front end, and the vacuum degree of each vent was set to 27hPa for each of the rear vent 798hPa, the 1 st vent 266hPa, and the 2 nd vent to the 4 th vent, to perform devolatilization. At this time, ion-exchanged water was poured from the rear of the 2 nd and 4 th vents at a pouring rate of 0.47 parts/hour, and a toluene solution of zinc octoate (manufactured by Nikka Octhix Zinc 18% ", irganox 1010 (manufactured by Ciba Specialty Chemicals)) and ADK STAB AO-412S (manufactured by ADEKA) was poured so that the mass ratio of zinc octoate was 160ppm, irganox 1010 and ADK STAB AO-412S was 50ppm, respectively, relative to the obtained thermoplastic resin composition.

After completion of devolatilization, the resin composition in a hot-melt state remaining in the extruder was discharged from the front end of the extruder while being filtered by the above polymer filter, passed through a die provided therein, and then filtered by a filter having a pore size of 1 μm (product name: microporous filter 1EU manufactured by Organo corporation), cooled in a water tank filled with cooling water maintained at a temperature in the range of 30.+ -. 10 ℃ and then introduced into a cutter (granulator), whereby pellets composed of a resin composition (7A) containing a lactone ring-type polymer having a lactone ring structure in its main chain were obtained. The weight average molecular weight of the obtained resin composition (7A) was 13.2 ten thousand, the number average molecular weight was 5.9 ten thousand, the glass transition temperature was 121℃and the thermal decomposition initiation temperature was 335℃and the refractive index was 1.501.

Then, the produced pellets (7A) were formed into films in the same manner as in production example 1, to obtain stretched acrylic resin films (F7).

Production example 11

To the stirred pure water, 0.09 wt% of an emulsion containing fine amorphous silica particles (Japanese catalyst manufacture, seahostar KE-W30, average particle diameter (primary particle diameter) 0.28 μm, particle size distribution 1.1, solid content 20 wt%), 20 wt% of a urethane resin (first Industrial pharmaceutical manufacture, super Flex 210, solid content 35 wt%) and 0.0007 wt% of a polyamine (Japanese catalyst manufacture, EPOMIN SP-006) were added in this order and thoroughly mixed, and the mixture was passed through a 1 μm filter to obtain an easily adhesive composition (1B) as an emulsion-like dispersion. The remainder after removing the polyurethane resin, silica particles and polyamine from the easy-to-adhere composition is pure water.

Production examples 12 to 83

Using the raw materials shown in Table 1A, table 1B and Table 1C below, adhesive compositions (2B to 73B) as emulsion-like dispersions were obtained in the same manner as in production example 11. The crosslinking agent is added after the polyurethane resin and before the polyamine is added.

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SF210: first Industrial pharmaceutical manufacture, super Flex 210, 35 wt% solids

W-5030: triplex chemical polyurethane production, takelac W-5030, solid content 30 wt%

CP-7020: DIC, hydroan CP-7020, 40% by weight of solid content

SF620: first Industrial pharmaceutical manufacture, super Flex 620, solid content 30 wt%

AP-40N: DIC, hydroan AP-40N, solid content 35 wt%

KE-W30: japanese catalyst manufacture, seahostar KE-W30, average particle diameter (primary particle diameter) of 0.28 μm, particle size distribution of 1.1, solid content of 20 wt%

KE-W10: japanese catalyst manufacture, seahostar KE-W10, average particle diameter (primary particle diameter) of 0.11 μm, particle size distribution of 1.1, solid content of 15 wt%

SP-006: japanese catalyst manufacture, EPOMIN SP-006

WS-700: japanese catalyst manufacture, epocros WS-700, solid content 25 wt%

(3) Examples

Example 1

One surface of the acrylic resin film (F1) produced in production example 1 was coated with the adhesive composition (1B) produced in production example 11 so that the thickness of the dried coating film was 270nm, and then the whole was dried at 100℃for 2 minutes. Thus, an optical film having an easily adhesive layer formed on one surface was obtained. The fine particles contained in the formed easy-adhesion layer maintain the shape in the easy-adhesion composition (1B).

Examples 2 to 58 and comparative examples 1 to 16

As shown in tables 2A to 2C below, the combination of the acrylic resin film and the adhesive composition was changed, and an optical film having an adhesive layer formed on one surface was obtained in the same manner as in example 1.

The evaluation results of the optical films produced in each of the examples and comparative examples are summarized in tables 2A, 2B and 2C below.

[ Table 2A ]

[ Table 2B ]

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[ Table 2C ]

Example 59

One surface of the acrylic resin film (F1) produced in production example 1 was coated with the composition (1B) produced in production example 11 by using a coating machine so that the thickness of the dried coating film was 600nm, and then the whole was dried at 100℃for 2 minutes. Next, the film thus obtained was subjected to free-end unidirectional stretching in the TD direction (direction orthogonal to the MD direction in the film plane, width direction in extrusion molding) at a stretching ratio of 1.5 times and a stretching temperature of 140 ℃ using a biaxial stretching machine (TYPE EX4 manufactured by eastern jejunum), to obtain an optical film composed of an acrylic resin film as a biaxially stretched film, in which an easily adhesive layer containing a polyurethane resin and fine particles was formed on one surface.

Comparative example 17

As shown in table 3 below, the combination of the acrylic resin film and the easy-to-adhere composition was changed, and an optical film having an easy-to-adhere layer formed on one surface was obtained in the same manner as in example 11.

The evaluation results of the optical films produced in the examples and comparative examples are summarized in table 3 below.

TABLE 3

Example 60

A single screw extruder equipped with a polymer filter (filtration accuracy: 5 μm) and a T-die at the front end was usedL/d=32), and the pellets (1A) of the acrylic resin produced in production example 1 were melt-extruded at a processing rate of 200 kg/hour (resin amount conversion) and a temperature of 270 ℃ to produce a belt-like acrylic resin film having a thickness of 220 μm. Subsequently, the produced acrylic resin film was continuously fed to an oven longitudinal stretching machine after melt extrusion, and was stretched (longitudinal stretching) by the stretching machine at a stretching temperature of 142 ℃ and a stretching ratio of 1.5 times in the longitudinal direction (flow direction and MD direction in melt extrusion) of the acrylic resin film.

Further, the composition (11B) for easy adhesion produced in production example 21 was applied to one surface of the acrylic resin film after longitudinal stretching by gravure coating so that the thickness of the dried coating film became 1050nm (in-line coating), and then the acrylic resin film was directly fed to a transverse tenter to be stretched (transverse stretching) at a stretching temperature of 132 ℃ and a stretching ratio of 3.0 times in the width direction. An optical film (thickness: 58 μm) comprising an acrylic resin film as a biaxially oriented film, in which an easy-to-adhere layer (thickness: 350 nm) comprising a urethane resin and fine particles was formed on one main surface, was thus obtained.

Examples 61 to 79 and comparative examples 18 to 20

As shown in table 4 below, the combination of the resin pellets and the easy-to-adhere composition was changed, and an optical film having an easy-to-adhere layer formed on one surface was obtained in the same manner as in example 57.

The evaluation results of the optical films produced in the examples and comparative examples are summarized in table 4 below.

TABLE 4

Example 80

A single screw extruder equipped with a polymer filter (filtration accuracy: 5 μm) and a T-die at the front end was usedL/d=32), and the pellets (1A) of the acrylic resin produced in production example 1 were melt-extruded at a processing rate of 200 kg/hour (resin amount conversion) and a temperature of 270 ℃ to produce a film in the form of a belt having a thickness of 220 μm. Subsequently, the produced film was continuously fed to an oven machine direction stretcher after melt extrusion, and the film was stretched (machine direction stretching) at a stretching temperature of 142 ℃ and a stretching ratio of 1.5 times in the machine direction (flow direction and MD direction in melt extrusion) by the stretcher.

Further, after corona treatment was performed on one main surface of the acrylic resin film after longitudinal stretching, the adhesive composition (11B) produced in production example 21 was applied to the treated surface by a gravure coating method so that the thickness of the dried coating film was 1050nm (in-line coating). Subsequently, the acrylic resin film was directly fed to a transverse tenter stretching machine, and stretched (transverse stretching) at a stretching temperature of 132 ℃ and a stretching ratio of 3.0 times in the width direction thereof. An optical film (thickness: 58 μm) comprising an acrylic resin film as a biaxially oriented film, in which an easy-to-adhere layer (thickness: 350 nm) comprising a urethane resin and fine particles was formed on one main surface, was thus obtained.

Examples 81 to 82 and comparative example 21

As shown in table 5 below, the combination of the resin pellets and the easy-to-adhere composition was changed, and an optical film having an easy-to-adhere layer formed on one main surface was obtained in the same manner as in example 13.

The evaluation results of the optical films produced in the examples and comparative examples are summarized in table 5 below.

TABLE 5

As shown in tables 2A to 5, the adhesive layer contains a binder resin, polyamine, and fine particles, and the polyamine content in the adhesive layer is set to 0.0090 wt% to 1.4100 wt%, whereby the adhesive layer having excellent adhesion between the resin film and the adhesive layer and being uniform can be formed. Speculation: if a polyamine of a polymer is used, the adhesion between the resin film and the adhesive layer is further improved by the interaction between the polyamine and the substrate film. In addition, it can be seen that: the polyamine content of 0.0489 mass% or more can ensure blocking resistance. This is presumably because the addition of the polyamine increases the tackiness of the adhesive composition and increases the retention of fine particles. Speculation: by adding polyamine, the tackiness of the substrate portion of the adhesive layer is improved, and the particles are prevented from being buried in the coating liquid during drying. Furthermore, it is presumed that: the polyamine also provides an effect of inhibiting the falling-off of fine particles. In contrast, comparative examples 1 to 11, 13, 15, 17 to 20 using the easy-to-adhere composition (14B to 23B, 39B, 57B) having a polyamine content of less than 0.0090% by weight failed to satisfy the adhesion. In addition, comparative examples 12, 14, and 16 using the easy-to-adhere composition (37B, 56B, and 73B) having a polyamine content exceeding 1.4100 wt% failed to satisfy uniformity of the easy-to-adhere composition or the easy-to-adhere layer. This is presumably because the viscosity of the adhesive composition becomes excessively high by adding polyamine in an excessive amount.

Industrial applicability

The optical film of the present invention is suitable for various protective films such as a polarizing element protective film, a retardation film, and a polarizing film, for use in an image display device such as an LCD.

Claims

1. An optical film comprising a resin film and an easily adhesive layer formed on the surface of the resin film, wherein,

the easy-to-adhere layer contains a binder resin, polyamine and fine particles,

the polyamine is a polymer having more than 2 amino groups,

the 2 or more amino groups include at least 1 selected from the group consisting of secondary amino groups and tertiary amino groups,

the polyamine content in the adhesive layer is 0.0090 to 1.4100 wt%.

2. The optical film of claim 1 wherein the binder resin comprises a polyurethane resin.

3. The optical film of claim 1 or 2, wherein the 2 or more amino groups comprise a primary amino group, the secondary amino group, and the tertiary amino group.

4. An optical film according to any one of claims 1 to 3, wherein the polyamine comprises a polyalkyleneimine.

5. The optical film according to claim 4, wherein the polyalkyleneimine contains a primary amino group, the secondary amino group and the tertiary amino group, and has a branched structure.

6. The optical film according to any one of claims 1 to 5, wherein the resin film comprises a (meth) acrylic polymer.

7. An optical member comprising the optical film according to any one of claims 1 to 6.

8. An image display device provided with the optical film according to any one of claims 1 to 6.

9. A method for producing an optical film according to any one of claims 1 to 6, wherein,

a coating film of an easy-to-adhere composition comprising a binder resin, a polyamine and fine particles is formed by coating the surface of a resin film,

drying the coating film to form an easy-to-adhere layer containing the binder resin, the polyamine and the fine particles on the surface of the resin film,

the polyamine is a polymer having more than 2 amino groups,

the 2 or more amino groups include at least 1 selected from the group consisting of secondary amino groups and tertiary amino groups.