JP2012032768A - Optical film and method for producing the same, optical member and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical film and a method for producing the film comprising an acrylic resin film having an easy-to-adhere layer formed on the surface thereof, the film achieving both of antiblocking property and transparency.SOLUTION: The optical film comprises an acrylic resin film having an easy-to-adhere layer formed on the surface thereof, in which the easy-to-adhere layer contains fine particles and the fine particles included in the easy-to-adhere layer have an average primary particle diameter of over 200 nm and a grain size distribution of 1.0 to 1.4. The optical film is suitably used for various kinds of protective films such as a protective film of a polarizer, retardation films and polarization films used for an image display device such as a liquid crystal display device (LCD).

Description

  The present invention relates to an optical film composed of an acrylic resin film having an easy-adhesion layer formed on the surface, and a method for producing the same. Furthermore, this invention relates to an optical member provided with the said optical film, and an image display apparatus.

  An acrylic resin containing a (meth) acrylic polymer typified by polymethyl methacrylate (PMMA) is excellent in optical properties such as light transmittance and excellent in balance between mechanical strength, molding processability and surface hardness. For this reason, acrylic resins are widely used as transparent materials in various industrial products such as automobiles and home appliances. In recent years, there are an increasing number of cases in which acrylic resins are used for optical applications. In particular, the application of acrylic resin to an optical film incorporated in an image display device such as a liquid crystal display device (LCD), a plasma display panel (PDP), or an organic EL display device (OELD) has been promoted.

  An optical film may be used in the state laminated | stacked with the other functional film. For example, a polarizer protective film which is a kind of optical film is usually used in an image display device in a state of a polarizing plate laminated with a polarizer. A polarizing plate usually has a configuration including a polarizer and a polarizer protective film bonded to at least one surface of the polarizer via an adhesive layer.

  When an acrylic resin is used for an optical film, an easy-adhesion layer may be formed on the surface of the optical film in consideration of lamination with other functional films. The easy-adhesion layer is a layer that improves the adhesiveness of the optical film and ensures lamination with another film via the adhesive layer. Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2007-127893) discloses a polarizing plate including a polarizer and a polarizer protective film bonded to at least one surface of the polarizer via an adhesive. In addition to this, Patent Document 1 discloses that an easy-adhesion layer containing a polyurethane resin and / or an amino group-containing polymer is formed on the surface of the polarizer protective film facing the polarizer. Patent Document 2 (Japanese Patent Application Laid-Open No. 2010-55062) discloses a polarizer protective film having an acrylic resin film and an easy-adhesion layer formed from an easy-adhesion composition containing a urethane resin and fine particles. Patent Document 2 describes that by forming an easy-adhesion layer from an easy-adhesion composition containing a urethane resin and fine particles, blocking when the polarizer protective film is wound around a roll is suppressed.

JP 2007-127893 JP JP 2010-55062 A

  However, simply adding fine particles to the easy-adhesion layer does not necessarily achieve good blocking resistance. If the content of the fine particles in the easy-adhesion layer is increased for the purpose of realizing good blocking resistance, the strength and easy-adhesion property of the easy-adhesion layer are lowered. When the particle size of the fine particles contained in the easy-adhesion layer is increased, the easy-adhesion layer becomes cloudy, and the transparency of the optical film having the layer decreases, making it unsuitable for use in optical applications.

  An object of the present invention is to provide an optical film composed of an acrylic resin film having an easy-adhesion layer formed on the surface thereof, which has both blocking resistance and transparency, and a method for producing the same.

  The optical film of this invention is comprised from the acrylic resin film in which the easily bonding layer was formed in the surface. The easy adhesion layer includes fine particles. The average primary particle diameter of the fine particles contained in the easy adhesion layer exceeds 200 nm. The particle size distribution of the fine particles contained in the easy adhesion layer is 1.0 to 1.4.

  The optical member of the present invention includes the optical film of the present invention.

  The image display device of the present invention includes the optical film of the present invention.

  In the method for producing an optical film of the present invention, on the surface of the acrylic resin film, an easy-adhesive composition containing fine particles is applied to form a coating film of the composition (application process), and the coating film is dried, An easy adhesion layer containing the fine particles is formed on the surface (drying step). Here, the average primary particle diameter of the fine particles contained in the easy-adhesion composition exceeds 200 nm. The particle size distribution of the fine particles is 1.0 to 1.4. Thereby, the optical film of the present invention is formed.

  ADVANTAGE OF THE INVENTION According to this invention, it is an optical film comprised from the acrylic resin film in which the easily bonding layer was formed in the surface, Comprising: The optical film which was compatible with blocking resistance and transparency is obtained.

It is sectional drawing which shows an example of the optical film of this invention typically. It is sectional drawing which shows typically an example of the structure of the image display part in the image display apparatus of this invention.

  Unless otherwise specified, “resin” in this specification is a broader concept than “polymer”. The resin may be composed of, for example, one type or two or more types of polymers, and if necessary, materials other than the polymer, for example, additives such as ultraviolet absorbers, antioxidants, fillers, and compatibilizing agents. Further, it may contain a stabilizer and the like.

[Acrylic resin film]
An acrylic resin film is a film comprised from the acrylic resin containing a (meth) acrylic polymer. The acrylic resin film is obtained by molding an acrylic resin. 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. That's it. The (meth) acrylic polymer has excellent optical properties such as high light transmittance and low wavelength dependency of refractive index. For this reason, the acrylic resin containing a (meth) acrylic polymer is suitable for use for an optical film.

  The (meth) acrylic polymer is a polymer having a structural unit ((meth) acrylic acid ester unit) derived from a (meth) acrylic acid ester monomer. The content of the (meth) acrylic acid ester 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 (meth) acrylic polymer may have a ring structure in the main chain. The ring structure is obtained by, for example, copolymerizing a (meth) acrylate monomer and a monomer having a ring structure, or polymerizing a monomer group including a (meth) acrylate monomer. By proceeding with the cyclization reaction, it is introduced into the main chain of the (meth) acrylic polymer. When the polymer has a ring structure in the main chain, the polymer is a (meth) acrylic polymer if the total content of the (meth) acrylic acid ester unit and the ring structure is 50% by weight or more.

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

  The (meth) acrylic polymer may have a structural unit other than the (meth) acrylic acid ester unit. Such structural units include, for example, styrene, vinyl toluene, α-methylstyrene, α-hydroxymethylstyrene, α-hydroxyethylstyrene, acrylonitrile, methacrylonitrile, ethylene, propylene, 4-methyl-1-pentene, acetic acid. It is a structural unit derived from each monomer of vinyl, 2-hydroxymethyl-1-butene, methyl vinyl ketone, N-vinyl pyrrolidone, and N-vinyl carbazole. The (meth) acrylic polymer may have two or more of these structural units. When the (meth) acrylic polymer has N-vinylpyrrolidone units or N-vinylcarbazole units, the degree of freedom in controlling the birefringence wavelength dispersibility in the optical film is improved. For example, in the visible light region, a retardation film exhibiting wavelength dispersibility (so-called reverse wavelength dispersibility) can be obtained as the birefringence decreases (the absolute value of the phase difference decreases) as the wavelength of light decreases. The retardation film can be a positive retardation film.

  When a cyclic structure is introduced into the main chain by a cyclization reaction after polymerization, the (meth) acrylic polymer is formed by copolymerization of a monomer group including a monomer having a hydroxyl group and / or a carboxylic acid group. Is preferred. 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, These are 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. Two or more of these monomers may be used. These monomers become a ring structure located in the main chain of the (meth) acrylic polymer by a cyclization reaction, but it is not necessary that all of the monomers change into a ring structure during the cyclization reaction. The (meth) acrylic polymer after the cyclization reaction may have a structural unit derived from these monomers.

  The weight average molecular weight of the (meth) acrylic polymer is preferably 10,000 to 500,000, more preferably 50,000 to 300,000.

  The (meth) acrylic polymer preferably has a ring structure in the main chain. The acrylic resin film preferably contains a (meth) acrylic polymer having a ring structure in the main chain. In this case, the heat resistance and hardness of the optical film are improved. In addition to this, the ring structure of the main chain contributes to the development of a large retardation in the acrylic resin film by stretching. This feature enables the use of the optical film of the present invention as a polarizer protective film having a retardation film or retardation film function.

  The ring structure that the (meth) acrylic polymer may have in the main chain is, for example, at least one selected from an N-substituted maleimide structure, a maleic anhydride structure, a glutarimide structure, a glutaric anhydride structure, and a lactone ring structure. It is a seed. The N-substituted maleimide structure is, for example, a cyclohexylmaleimide structure, a methylmaleimide structure, a phenylmaleimide structure, or a benzylmaleimide structure. From the viewpoint of the heat resistance of the optical film, the ring structure includes a lactone ring structure, a cyclic imide structure (for example, an N-alkyl-substituted maleimide structure, a glutarimide structure), and a cyclic anhydride structure (for example, a maleic anhydride structure and an anhydrous structure). Glutaric acid structure) is preferred. When the optical film of the present invention is a retardation film, the ring structure is preferably a lactone ring structure, a glutarimide structure, or a glutaric anhydride structure from the viewpoint of imparting a positive retardation to the film. From the viewpoint of improving the birefringence wavelength dispersibility in the retardation film, the structure is preferably a lactone ring structure.

  The lactone ring structure is usually a 4- to 8-membered ring, preferably a 5- to 6-membered ring, more preferably a 6-membered ring from the viewpoint of structural stability. The 6-membered lactone ring structure is preferably a structure represented by the following formula (1). The structure represented by formula (1) has the following advantages: the polymerization yield of the precursor before introducing the lactone ring structure into the main chain by a cyclization reaction is high; the content of the ring structure is high (meta) Easy to obtain acrylic polymer; high copolymerization with (meth) acrylic acid ester monomers such as methyl methacrylate (MMA).

In the formula (1), R ¹ , R ² and R ³ are each independently a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue may contain an oxygen atom.

  The organic residue is, for example, an alkyl group having 1 to 20 carbon atoms such as a methyl group, an ethyl group, or a propyl group; an unsaturated aliphatic carbonization having 1 to 20 carbon atoms such as an ethenyl group or a propenyl group. A hydrogen group; an aromatic hydrocarbon group having 1 to 20 carbon atoms such as a phenyl group or a naphthyl group; one of the hydrogen atoms in the alkyl group, the unsaturated aliphatic hydrocarbon group or the aromatic hydrocarbon group; The above is a group substituted with at least one group selected from a hydroxyl group, a carboxyl group, an ether group and an ester group.

The lactone ring structure represented by the formula (1) is adjacent to each other in the obtained copolymer after copolymerization of a monomer group including, for example, MMA and methyl 2- (hydroxymethyl) acrylate (MHMA). It can be formed by dealcoholization cyclocondensation of MMA units and MHMA units. At this time, R ¹ is H, R ² is CH ₃ , and R ³ is CH ₃ .

  When the (meth) acrylic polymer has a ring structure in the main chain, 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, and more. Preferably it is 10 to 60 weight%, More preferably, it is 10 to 50 weight%. When the content of the ring structure is excessively large, the stretchability and handling properties of the acrylic resin film are lowered. If the content of the ring structure is excessively small, the effect resulting from the ring structure cannot be obtained.

  The (meth) acrylic polymer having a ring structure in the main chain can be formed by a known method.

  Examples of the (meth) acrylic polymer having a lactone ring structure in the main chain include, for example, JP 2000-230016, JP 2001-151814, JP 2002-120326, JP 2002-254544, It is a polymer described in JP 2005-146084 A, and can be formed by the method described in the publication.

  The (meth) acrylic polymer having a glutaric anhydride structure in the main chain is, for example, a polymer described in JP 2006-283013 A, JP 2006-335902 A, or JP 2006-274118 A. Yes, it can be formed by the method described in the publication.

  Examples of the (meth) acrylic polymer having a glutarimide structure in the main chain include, for example, JP-A-2006-309033, JP-A-2006-317560, JP-A-2006-328329, JP-A-2006-328334, JP-A-2006-337491, JP-A-2006-337492, JP-A-2006-337493, JP-A-2006-337569, JP-A-2007-009182 It can be formed by the method described in the publication.

  When the optical film of the present invention is a retardation film or a functional film exhibiting a retardation, the acrylic resin film has a composition that expresses the retardation by stretching.

  The acrylic resin film may contain a thermoplastic polymer other than the (meth) acrylic polymer as long as the effect of the present invention is obtained. Other thermoplastic polymers include, for example, polyethylene, polypropylene, ethylene-propylene copolymers, olefin polymers such as poly (4-methyl-1-pentene); polyvinyl chloride, polyvinylidene chloride, polychlorinated vinyl, etc. Styrene polymers such as polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene block copolymer; polyethylene terephthalate, polybutylene terephthalate, polyethylene Polyester such as phthalate; Polyamide such as nylon 6, nylon 66, nylon 610; Polyacetal; Polycarbonate; Polyphenylene oxide; Polyphenylene sulfide; Polyether ether ketone; Sulfone; polyethersulfones; polyoxyethylene benzylidene alkylene; polyamideimide; polybutadiene rubber or ABS resin containing an acrylic rubber, rubber-like polymer such as ASA resin; a.

  When the acrylic resin film is a stretched film containing a styrenic polymer, the positive phase difference exhibited by the (meth) acrylic polymer having a ring structure in the main chain is canceled by the negative phase difference exhibited by the styrenic polymer. be able to. Depending on the content of the styrenic polymer in the acrylic resin film, the optical film of the present invention which is a stretched film can be a negative retardation film or a low retardation polarizer protective film. When the acrylic resin film contains a styrene polymer, the styrene polymer is preferably a styrene-acrylonitrile copolymer from the viewpoint of compatibility with the (meth) acrylic polymer. When the acrylic resin film contains ABS resin or ASA resin, depending on the content of the resin in the acrylic resin film, the optical film of the present invention which is a stretched film may be a negative retardation film or a low retardation film, Flexibility is improved.

  The content of the other thermoplastic polymer in the acrylic resin film is preferably 0 to 50% by weight, more preferably 0 to 40% by weight, further preferably 0 to 30% by weight, particularly preferably 0 to 20% by weight. is there.

  The acrylic resin film may contain materials other than the polymer, for example, additives. Additives include, for example, hindered phenol-based, phosphorus-based, sulfur-based antioxidants; light-resistant stabilizers, weather-resistant stabilizers, thermal stabilizers, and other stabilizers; reinforcing materials such as glass fibers and carbon fibers; UV absorbers such as tyrates, (2,2′-hydroxy-5-methylphenyl) benzotriazole, 2-hydroxybenzophenone; near infrared absorbers; difficulties such as tris (dibromopropyl) phosphate, triallyl phosphate, antimony oxide Antistatic agent composed of anionic, cationic and nonionic surfactants; Colorants such as inorganic pigments, organic pigments and dyes; Organic fillers, inorganic fillers; Antiblocking agents; Resin modifiers; Organic Fillers, inorganic fillers; plasticizers; lubricants; retardation reducing agents.

  The content of the additive in the acrylic resin film 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 film is preferably 100 ° C. or higher, more preferably 110 ° C. or higher, still more preferably 115 ° C. or higher, and particularly preferably 120 ° C. or higher. Although the upper limit of Tg of an acrylic resin film is not specifically limited, From a viewpoint of the drawability of the said film, Preferably it is 170 degrees C or less.

  The (meth) acrylic polymer having a ring structure in the main chain increases the Tg of an acrylic resin film and an optical film composed of the film, and improves heat resistance.

  The thickness of an acrylic resin film is not specifically limited, Preferably it is 5-200 micrometers, More preferably, it is 10-100 micrometers. If the thickness is less than 5 μm, sufficient strength as an optical film may not be maintained. If the thickness exceeds 200 μm, the transparency of the film may be reduced, making it unsuitable for use as an optical film. In addition to this, the thickness of the excessively large acrylic resin film allows the adhesive composition used for the adhesive layer to be dried when the optical film of the present invention is bonded to another member (for example, a functional film). Inhibit. In particular, when using a water-based adhesive composition, the quality and production of an optical member having a laminated structure of the optical film of the present invention and other members is slowed by drying of water as a solvent or dispersion medium. It tends to cause a decline in sex.

  The wetting tension on the surface of the acrylic resin film is preferably 40 mN / m or more, more preferably 50 mN / m or more, and further preferably 55 mN / m or more. When the surface wetting tension is 40 mN / m or more, the adhesion between the optical film of the present invention and other members is further improved. In order to adjust the surface wetting tension, any appropriate surface treatment may be applied to the surface of the acrylic resin film. The surface treatment is, for example, corona discharge treatment, plasma treatment, ozone spraying, ultraviolet irradiation, flame treatment, or chemical treatment. Of these, corona discharge treatment and plasma treatment are preferred.

  The acrylic resin film may be an unstretched film or a stretched film. The stretched film may be a uniaxially stretched film or a biaxially stretched film. The biaxially stretched film may be a simultaneous biaxially stretched film or a sequential biaxially stretched film. When the acrylic resin film is a biaxially stretched film, the mechanical strength of the optical film of the present invention is improved. Depending on the composition of the acrylic resin, the development of retardation due to stretching can be suppressed, and an optically isotropic optical film can be obtained. When the optical film of the present invention is a retardation film, the acrylic resin film is a stretched film.

  The acrylic resin film can be formed by a known film deposition method. Examples of the film forming method include a solution casting method (solution casting method), a melt extrusion method, a calendar method, and a compression molding method. Of these, 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, an acrylic resin is formed by sufficiently mixing (meth) acrylic polymer, other thermoplastic polymer and additives blended according to the composition of the acrylic resin to be obtained by an appropriate mixing method. . The mixing method is, for example, extrusion kneading or mixing in a solution state. A commercially available acrylic resin may be used for film formation. Commercially available acrylic resins are, for example, Acrypet VH and Acrypet VRL20A (both manufactured by Mitsubishi Rayon). Any suitable mixer such as an omni mixer, a single screw extruder, a twin screw extruder, or a pressure kneader can be used for the extrusion kneading.

  An apparatus for performing the solution casting method is, for example, a drum type casting machine, a band type casting machine, or a spin coater.

  The solvent used for the solution casting method is not limited as long as the acrylic resin is dissolved. Examples of the solvent include 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, and methyl isobutyl ketone. Alcohols such as methanol, ethanol, isopropanol, butanol, isobutanol, methyl cellosolve, ethyl cellosolve, butyl cellosolve; ethers such as tetrahydrofuran and dioxane; halogenated hydrocarbons such as dichloromethane, chloroform and carbon tetrachloride; dimethylformamide; dimethyl sulfoxide is there. Two or more of these solvents may be used in combination.

  Examples of the melt extrusion method include a T-die method and an inflation method. The molding temperature during melt extrusion is preferably 150 to 350 ° C, more preferably 200 to 300 ° C. When the T-die method is selected, for example, a belt-like acrylic resin film can be formed by attaching a T-die to the tip of a known extruder. The formed strip-shaped acrylic resin film may be wound on a roll to form a film roll. In the melt extrusion method, from the formation of an acrylic resin by mixing materials to the formation of an acrylic resin film using the resin can be continuously performed. A band-shaped optical film may be obtained by forming an easy-adhesion layer on the band-shaped acrylic resin film.

  The acrylic resin film which is a stretched film can be formed by stretching the acrylic resin film obtained as described above. The stretching method is not particularly limited, and a known stretching machine can be used for stretching. When the acrylic resin film is formed by the T-die method, the temperature of the roll for winding the formed film can be adjusted to simultaneously perform uniaxial stretching and film winding.

  When the acrylic resin film is formed by melt extrusion, steps from the formation of the acrylic resin by mixing the materials to the formation of the optical film as the stretched film through the formation of the acrylic resin film can be performed continuously.

  After stretching, heat treatment (annealing) of the film may be performed in order to stabilize the optical isotropy and mechanical properties of the film. The heat treatment method and conditions can be selected as appropriate.

[Easily adhesive layer]
In the optical film of the present invention, an easy adhesion layer is formed on the surface of the acrylic resin film. The easy adhesion layer contains fine particles. The average primary particle diameter of the fine particles contained in the easy-adhesion layer exceeds 200 nm, and the particle size distribution of the fine particles is 1.0 to 1.4. In the optical film of the present invention, this easy-adhesion layer achieves both blocking resistance and transparency while achieving an effect of improving adhesion to other members such as a functional film. Conventionally, when adding fine particles to an easy-adhesion layer for the purpose of improving the blocking resistance of an optical film, it has been considered that the fine particles should have a smaller particle size. Patent Document 2 (Japanese Patent Laid-Open No. 2010-55062) discloses that the average primary particle diameter of the fine particles added to the easy-adhesion layer is preferably 10 to 200 nm and more preferably 20 to 60 nm. However, according to the study by the present inventors, it is actually difficult to ensure blocking resistance with such fine particles having a small particle diameter. On the other hand, in the easy-adhesion layer of the optical film, the particle size of the fine particles contained in the layer cannot be simply increased. This is because if the particle diameter of the fine particles is increased, a scattering phenomenon in the visible light region occurs, the film becomes cloudy and cannot be used as an optical film. The inventors of the present invention realized an optical film having both blocking resistance and transparency by making the particle size distribution a specific range in addition to the average primary particle size of the fine particles.

  The average primary particle size and particle size distribution of the fine particles can be determined by a laser diffraction / scattering particle size distribution measuring apparatus (for example, Submicron Particle Sizer NICOMP380 manufactured by Particle Sizing Systems). Specifically, the equivalent spherical distribution of the fine particles dispersed in the medium is obtained by the measuring device. The distribution determines a range where the primary particle diameter of the particles is 100 nm or more. Fine particles having an average primary particle diameter exceeding 200 nm and a particle size distribution of 1.0 to 1.4 usually do not include particles having a primary particle diameter of less than 100 nm, or the distribution is negligible. There are only a few. Therefore, in evaluating the average primary particle size and particle size distribution of the fine particles, it is not necessary to consider particles having a primary particle size of less than 100 nm. Even if there is a particle group having the most frequent primary particle diameter of less than 100 nm, the particle group has the effect of the present invention, that is, both the transparency and blocking resistance of the optical film. There is no need to consider it because it has no effect. Next, in the obtained distribution, the particle diameter of particles with an integrated volume fraction of 50% accumulated from the large particle side is obtained, and this is used as the average primary particle diameter (d50) of the fine particles. Separately from this, the particle diameter (d25) of particles with an integrated volume fraction of 25% and the particle diameter (d75) of 75% of particles accumulated from the large particle side in the distribution are obtained, and the ratio (d25 / d75) Is the particle size distribution of the fine particles. In addition, although a medium can be suitably selected according to the structure and capability of a particle size distribution apparatus, for example, it is water, it is not restricted to a liquid.

  As long as the average primary particle diameter is 200 nm or more and the particle size distribution is 1.0 to 1.4, the fine particles contained in the easy-adhesion layer are not limited. Any microparticle can be used.

  The average primary particle diameter of the fine particles is preferably 220 nm or more, more preferably 250 nm or more, and further preferably 280 nm or more. The upper limit of the average primary particle diameter of the fine particles is, for example, 1000 nm or less, preferably 500 nm or less, more preferably 400 nm or less, and further preferably 350 nm or less. The particle size distribution of the fine particles is preferably 1.0 to 1.2. When the fine particles have such an average primary particle size and particle size distribution, good blocking resistance is realized even with a small amount of fine particles added while maintaining transparency as an optical film.

  One preferable form of the fine particles is water-dispersible fine particles. The fine particles may be either inorganic fine particles or organic fine particles. Examples of inorganic fine particles include inorganic oxides such as silica, titania, alumina, and zirconia; fine particles such as calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate. It is. The organic fine particles are, for example, fine particles of silicone resin, fluorine resin, or acrylic resin.

  The fine particles are preferably silica fine particles. Silica fine particles have a high effect of improving blocking resistance. Moreover, since it is excellent in transparency, coloring of an optical film and an increase in the haze rate hardly occur. In addition to this, the silica fine particles have good dispersibility and dispersion stability in the easy-adhesion composition, and have high adhesion to the acrylic resin film.

  When the easy-adhesion composition is aqueous, the fine particles are preferably blended as an aqueous dispersion such as colloidal silica. As long as the ranges described above for the average primary particle size and particle size distribution are satisfied, the colloidal silica may be a commercial product.

  The upper limit of the content of fine particles in the easy-adhesion layer is preferably less than 1% by weight, more preferably less than 0.5% by weight, and even more preferably less than 0.3% by weight. If the content of the fine particles exceeds 1% by weight, the coating strength of the easy adhesion layer may be lowered. The lower limit of the content of fine particles in the easy-adhesion layer is preferably 0.1% by weight or more, more preferably 0.15% by weight or more, and further preferably 0.2% by weight or more. When the content of the fine particles is less than 0.1% by weight, the blocking resistance of the optical film may be lowered.

  Although the thickness of an easily bonding layer is not limited and changes with thickness of an acrylic resin film, 100 nm-10 micrometers are preferable, 100 nm-5 micrometers are more preferable, 200 nm-1.5 micrometers are more preferable. In this range, the effect of improving the adhesiveness of the optical film by the easy adhesion layer is good. In addition to this, it is possible to suppress the development of a phase difference in the easy-adhesion layer itself.

  The ratio r / d between the thickness d of the easy adhesion layer and the average primary particle diameter r of the fine particles contained in the easy adhesion layer is preferably 0.3 to 1.4, more preferably 0.4 to 1.1. 0.6 to 1.0 is more preferable. Within this range, the compatibility of blocking resistance and transparency in the optical film of the present invention is further ensured. If the average primary particle diameter r of the fine particles is smaller than the ratio r / d compared to the thickness d of the easy adhesion layer, the fine particles are included in the easy adhesion layer but are not exposed on the surface of the easy adhesion layer, that is, The proportion of fine particles that do not contribute to the improvement of blocking resistance but increase the haze ratio of the optical film increases, making it difficult to achieve both blocking resistance and transparency in the optical film. When the average primary particle diameter r of the fine particles is larger than the ratio r / d compared to the thickness d of the easy-adhesive layer, the strength of the easy-adhesive layer is reduced, and the fine particles easily fall off the easy-adhesive layer. Become.

  The resin constituting the easy-adhesion layer is not limited. The resin may be a known resin having easy adhesion, and examples thereof include a urethane resin, a cellulose resin, a polyol resin, a polycarboxylic acid resin, a polyester resin, and an acrylic resin.

  The number average molecular weight of the resin constituting the easy adhesion layer is preferably from 50,000 to 600,000, more preferably from 10,000 to 400,000.

  The resin constituting the easy-adhesion layer is preferably a urethane resin. That is, the easy adhesion layer is preferably a urethane resin layer containing fine particles. In this case, the adhesion of the easy adhesion layer to the acrylic resin film is improved and the easy adhesion of the optical film is improved as compared with the case where the easy adhesion layer is another resin layer.

  The urethane resin is not particularly limited, and is typically a resin obtained by reacting a polyol and a polyisocyanate. Any polyol having two or more hydroxyl groups in the molecule can be adopted as the polyol. The polyol is, for example, a polyacryl polyol, a polyester polyol, or a polyether polyol. Two or more polyols may be combined.

  The polyacryl polyol is typically a copolymer of a (meth) acrylic acid ester monomer and a monomer having a hydroxyl group. The (meth) acrylic acid ester monomer is, for example, methyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, or cyclohexyl (meth) acrylate. Examples of the monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, (Meth) acrylic acid hydroxyalkyl esters such as (meth) acrylic acid 4-hydroxybutyl and (meth) acrylic acid 2-hydroxypentyl; (meth) acrylic acid monoesters of polyhydric alcohols such as glycerin and trimethylolpropane; N -Methylol (meth) acrylamide.

  The polyacryl polyol may be a copolymer with further other monomers. The other monomer is not limited as long as it can be copolymerized with the (meth) acrylic acid ester monomer and the monomer having a hydroxyl group. Such other monomers include, for example, unsaturated monocarboxylic acids such as (meth) acrylic acid; unsaturated dicarboxylic acids such as maleic acid and anhydrides and mono- 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; α-olefins such as ethylene and propylene; Halogenated α, β-unsaturated aliphatic monomers such as vinyl chloride and vinylidene chloride; α, β-unsaturated aromatic monomers such as styrene and α-methylstyrene.

  The polyester polyol is typically obtained by reacting a polybasic acid component with a polyol component. Examples of the polybasic acid component include orthophthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, and tetrahydrophthalic acid. Aromatic dicarboxylic acids; 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, Aliphatic dicarboxylic acids such as linolenic acid, maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid; hexahydrophthalic acid, tetrahydrophthalic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, etc. Alicyclic dicarbo Acid; or their acid anhydrides are reactive derivative such as an alkyl ester, acid halide.

  Examples of the polyol component include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, and 1,6-hexanediol. 1,8-octanediol, 1,10-decanediol, 1-methyl-1,3-butylene glycol, 2-methyl-1,3-butylene glycol, 1-methyl-1,4-pentylene glycol, 2 -Methyl-1,4-pentylene glycol, 1,2-dimethyl-neopentyl glycol, 2,3-dimethyl-neopentyl glycol, 1-methyl-1,5-pentylene glycol, 2-methyl-1,5 -Pentylene glycol, 3-methyl-1,5-pentylene glycol, 1,2-dimethylbutylene Coal, 1,3-dimethylbutylene glycol, 2,3-dimethylbutylene glycol, 1,4-dimethylbutylene glycol, 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.

  The polyether polyol is typically obtained by adding an alkylene oxide to a polyhydric alcohol by ring-opening polymerization. The polyhydric alcohol is, for example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerin, or trimethylolpropane. The alkylene oxide is, for example, ethylene oxide, propylene oxide, butylene oxide, styrene oxide, tetrahydrofuran.

  Examples of the polyisocyanate include tetramethylene diisocyanate, dodecamethylene diisocyanate, 1,4-butane diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, Aliphatic diisocyanates such as 2-methylpentane-1,5-diisocyanate and 3-methylpentane-1,5-diisocyanate; isophorone diisocyanate, hydrogenated xylylene diisocyanate, 4,4'-cyclohexylmethane diisocyanate, 1,4-cyclohexane Alicyclic diisodies such as diisocyanate, methylcyclohexylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane Anate; tolylene diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyl diisocyanate, 1 , 5-naphthylene diisocyanate, xylylene diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate and other aromatic diisocyanates; dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, α, α, α, α-tetramethylxylylene An aromatic aliphatic diisocyanate such as range isocyanate.

  The urethane resin preferably has a carboxyl group. By having a carboxyl group, the performance (easy adhesion) of the easy adhesion layer is improved. This effect is particularly remarkable in a high temperature and high humidity environment. The urethane resin having a carboxyl group can be obtained, for example, by reacting a chain extender having a free carboxyl group in addition to a polyol and a polyisocyanate. Examples of the chain extender having a free carboxyl group are dihydroxycarboxylic acid and dihydroxysuccinic acid. The dihydroxycarboxylic acid is a dialkylol alkanoic acid such as dimethylol alkanoic acid (for example, dimethylol acetic acid, dimethylol butanoic acid, dimethylol propionic acid, dimethylol butyric acid, dimethylol pentanoic acid).

  The acid value of the urethane resin is preferably 10 or more, more preferably 10 to 50, and particularly preferably 20 to 45. In these cases, the performance of the easy-adhesion layer (for example, adhesion with other functional films such as a polarizer) is further improved.

  The urethane resin may be obtained by reaction with other polyols or other chain extenders in addition to the components described above. Other polyols include, for example, sorbitol, 1,2,3,6-hexanetetraol, 1,4-sorbitan, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerin, trimethylolethane , Trimethylolpropane, pentaerythritol, and other polyols having three or more hydroxyl groups. Other chain extenders include, for example, ethylene glycol, diethylene glycol, triethylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 1,6- Glycols such as hexanediol and propylene glycol; Aliphatic diamines such as ethylenediamine, propylenediamine, hexamethylenediamine, 1,4-butanediamine, and aminoethylethanolamine; Fats such as isophorone diamine and 4,4'-dicyclohexylmethanediamine Cyclic diamines; aromatic diamines such as xylylenediamine and tolylenediamine.

  The urethane resin can be formed by applying a known method. This method is, for example, a one-shot method in which each component is reacted at once, or a multi-stage method in which the components are reacted stepwise. The urethane resin having a carboxyl group is preferably formed by a multistage method since the introduction of the carboxyl group is easy. The catalyst used for forming the urethane resin is not particularly limited.

  The formation method of the easily bonding layer with respect to the surface of an acrylic resin film is not limited, What is necessary is just to follow a well-known method. The easy-adhesion layer is formed by applying an easy-adhesive composition containing an easy-adhesive resin and fine particles to the surface of the acrylic resin film to form a coating film of the composition, and then drying the formed coating film. It is preferable to form. The easy-adhesion composition is preferably an aqueous composition. The water-based composition has a smaller work load on the environment when forming the easy-adhesion layer than the organic solvent-based composition, and is excellent in workability. The aqueous composition is, for example, a resin dispersion having easy adhesion. The dispersion is typically an emulsion of resin having easy adhesion. The resin emulsion becomes a resin layer by drying. The fine particles contained in the emulsion remain in the resin layer as they are.

  The easy-adhesion composition may contain additives in addition to the fine particles and the resin having easy adhesion. Additives are, for example, dispersion stabilizers, thixotropic agents, antioxidants, ultraviolet absorbers, antifoaming agents, thickeners, dispersants, surfactants, catalysts, and antistatic agents.

  The water-based easy-adhesion composition used for forming the easy-adhesion layer that is a urethane resin layer preferably contains a neutralizing agent in addition to the fine particles and the urethane resin. In this case, the stability of the urethane resin in the easy-adhesion composition is improved. Examples of the neutralizing agent include ammonia, N-methylmorpholine, triethylamine, dimethylethanolamine, methyldiethanolamine, triethanolamine, morpholine, tripropylamine, ethanolamine, triisopropanolamine, 2-amino-2-methyl-1- Propanol.

  When the easy-adhesion composition containing a urethane resin is aqueous, it is preferable to use an organic solvent that is inactive with respect to the polyisocyanate and is compatible with water when forming the urethane resin. Examples of organic solvents include ester solvents such as ethyl acetate, butyl acetate, and ethyl cellosolve acetate; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ether solvents such as dioxane, tetrahydrofuran, and propylene glycol monomethyl ether. is there.

  It is preferable that the easily bonding composition containing a urethane resin contains a crosslinking agent, and in this case, the performance of the easily bonding layer is improved. The crosslinking agent is not particularly limited. When the urethane 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 a carboxyl group are an organic amino group, an oxazoline group, an epoxy group, and a carbodiimide group, and an oxazoline group is preferable. The crosslinking agent having an oxazoline group has a long pot life at room temperature when mixed with a urethane resin, and has a good workability because the crosslinking reaction proceeds by heating. The polymer is, for example, a (meth) acrylic polymer or a styrene / acrylic polymer, and a (meth) acrylic polymer is preferable. When the crosslinking agent is a (meth) acrylic polymer, the performance of the easy adhesion layer is further improved. In addition to this, the (meth) acrylic polymer is stably compatible with the water-based easy-adhesive composition and crosslinks the urethane resin well.

  In the easily bonding composition containing a urethane resin, the content of the urethane resin in the composition is preferably 1.5 to 15% by weight, and more preferably 2 to 10% by weight. When content rate exists in these ranges, the applicability | paintability at the time of apply | coating an easily bonding composition to the surface of an acrylic resin film is high. When this composition further contains a crosslinking agent, the content of the crosslinking agent is preferably 1 to 30 parts by weight and more preferably 3 to 20 parts by weight with respect to 100 parts by weight of the urethane resin (solid content). The content of fine particles in the easy-adhesion composition containing a urethane resin is preferably 0.3 to 10 parts by weight, and more preferably 0.5 to 1 part by weight with respect to 100 parts by weight of the urethane resin (solid content).

[Optical film, optical member]
FIG. 1 shows an example of the optical film of the present invention. An optical film 1 shown in FIG. 1 has a structure in which an easy adhesion layer 3 is formed on one surface of an acrylic resin film 2. Specific configurations of the acrylic resin film 2 and the easy-adhesion layer 3 are as described above.

  In the optical film of the present invention, an easy adhesion layer may be formed on both surfaces of the acrylic resin film.

  The optical film of the present invention is a film having an easy adhesion layer in which blocking resistance and transparency are compatible. Regarding transparency, the optical film of the present invention usually has a haze ratio of 0.5% or less. Depending on the configuration of the optical film of the present invention, the haze ratio is 0.4% or less, and further 0.2% or less. A haze rate is measured based on the prescription | regulation of JISK7136.

  The optical film of the present invention is, for example, a polarizer protective film, a retardation film, a viewing angle compensation film, a light diffusion film, a reflective film, an antireflection film, an antiglare film, a brightness enhancement film, and a conductive film for a touch panel. The retardation exhibited by the optical film of the present invention can be controlled by the composition and stretched state of the acrylic resin film. The optical film of the present invention may be an optically isotropic film or a film having optical anisotropy (for example, expressing birefringence such as retardation).

  The optical film of the present invention which is a retardation film is suitable for use in an image display device such as an LCD. The retardation film can be used, for example, for LCD color tone compensation and viewing angle compensation.

  Since the optical film of the present invention which is a retardation film has an easy-adhesion layer, it can be used in a form other than the form normally used as a retardation film. Specifically, for example, a form that is used by being bonded to a polarizer included 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 polarizer protective film for protecting the polarizer. This form is advantageous for making the LCD thinner and more functional because the polarizer protective film having no retardation which has been conventionally used separately from the retardation film can be omitted.

  The optical film of the present invention may be wound around a roll (may be a film roll). Since the optical film of the present invention is excellent in blocking resistance, it is suitable for a film roll.

  Various functional coating layers may be formed on the surface opposite to the surface on which the easy-adhesion layer in the optical film of the present invention is formed, if necessary. Functional coating layers include, for example, antistatic layers, adhesive layers, adhesive layers, easy adhesion layers, antiglare (non-glare) layers, antifouling layers such as photocatalyst layers, antireflection layers, hard coat layers, and UV shielding layers. Layers, heat ray shielding layers, electromagnetic wave shielding layers, gas barrier layers, and the like.

  The optical film of the present invention can be produced, for example, by the production method of the present invention.

  The optical film of the present invention can be bonded to other members such as a functional film to become an optical member. The optical member of the present invention includes the optical film of the present invention. At this time, it is preferable that the surface of the optical film of the present invention on the side of the easy adhesion layer is bonded to another member via the easy adhesion layer. Furthermore, the surface on the opposite side to the easy-adhesion layer side in the optical film of the present invention may be bonded to another member. Other members are not limited and are, for example, functional films.

  The optical film and optical member of the present invention are suitable for use in an image display device. The image display device is, for example, an electroluminescence (EL) display panel, a plasma display panel (PDP), a field emission display (FED), or an LCD. The LCD has a liquid crystal cell and a polarizing plate disposed on at least one main surface of the liquid crystal cell.

  The optical member of the present invention includes, for example, a polarizing plate, a retardation film (laminated retardation film), a light diffusion film, a reflection film, an antireflection film, an antiglare film, a brightness enhancement film, a conductive film for a touch panel, a diffusion plate, and a conductive plate. It is a light body and a prism sheet.

  A polarizing plate will be described as an example of the optical member of the present invention. A pair of polarizing plates is arranged in the LCD so as to sandwich the liquid crystal cell based on the principle of image display. The polarizing plate has, for example, a structure in which the optical film (polarizer protective film) of the present invention is laminated on at least one surface of a polarizer via an easy adhesion layer.

  Conventionally, a triacetyl cellulose (TAC) film has been used as the polarizer protective film. However, the TAC film does not have sufficient moisture and heat resistance, and when the TAC film is used as a polarizer protective film, the characteristics of the polarizing plate may be deteriorated under a high temperature or high humidity environment. Further, the TAC film has a retardation in the thickness direction, and this retardation adversely affects the viewing angle characteristics of an image display device such as an LCD, particularly a large screen image display device. On the other hand, since the optical film of the present invention, which is a polarizer protective film, is composed of an acrylic resin film, it can improve heat and moisture resistance and optical characteristics as compared to a TAC film.

  The polarizing plate is typically produced by laminating an optical film and a polarizer via an adhesive layer. When an optical film has an easily bonding layer, both are laminated | stacked so that an easily bonding layer may become a polarizer side. Specifically, for example, an adhesive composition that becomes an adhesive layer after drying is applied to one surface selected from a polarizer or an optical film, and then both are bonded and dried. Examples of the method for applying the adhesive composition include a roll method, a spray method, and a dipping method. When the adhesive composition contains a metal compound colloid, the adhesive composition is applied so that the thickness of the adhesive layer after drying is larger than the average particle diameter of the metal compound colloid particles. The drying temperature is typically 5 to 150 ° C, preferably 30 to 120 ° C. The drying time is typically 120 seconds or longer, preferably 300 seconds or longer.

  The polarizer is not limited, and any appropriate polarizer can be adopted depending on the function required for the polarizing plate. For example, a polarizer is made of 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). A film uniaxially stretched by adsorbing a dichroic substance such as a reactive dye; a polyene-based oriented film using a dehydrated PVA product or a dehydrochlorinated polyvinyl chloride product. Especially, the film which made the PVA-type film adsorb | suck a dichroic substance and was uniaxially stretched is preferable as a polarizer. This polarizer exhibits a high polarization dichroic ratio. The thickness of the polarizer is not limited and is generally about 1 to 80 μm.

  A polarizer uniaxially stretched by adsorbing iodine to a PVA-based film can be produced, for example, by dyeing a PVA-based film by immersing it in an aqueous solution containing iodine and uniaxially stretching at a stretch ratio of 3 to 7 times. The aqueous solution used for dyeing may contain boric acid, zinc sulfate, zinc chloride and the like as necessary. As an aqueous solution containing iodine, an aqueous solution of iodide such as potassium iodide may be used. The PVA film may be immersed in water and washed before dyeing. By washing the PVA-based film with water, dirt, an anti-blocking agent and the like present on the surface of the film can be removed. Furthermore, since the PVA film swells by washing with water, unevenness during dyeing is suppressed. Stretching may be performed before dyeing, after dyeing, or simultaneously with dyeing.

  The adhesive composition that becomes the adhesive layer after drying is not limited. The adhesive composition preferably contains a PVA-based resin.

  The PVA resin includes, for example, the following polymers: saponified products of polyvinyl acetate and derivatives thereof; saponified products of copolymers of vinyl acetate and other monomers; acetalization, urethanization, ether of PVA Modified, grafted or phosphate ester modified PVA. Examples of the other monomers include unsaturated carboxylic acids such as (anhydrous) maleic acid, fumaric acid, crotonic acid, itaconic acid and (meth) acrylic acid and esters thereof; α-olefins such as ethylene and propylene; Meta) allylsulfonic acid (soda), sulfonic acid soda (monoalkylmalate), disulfonic acid soda alkylmalate, N-methylolacrylamide, acrylamide alkylsulfonic acid alkali salt, N-vinylpyrrolidone, N-vinylpyrrolidone derivative . The PVA resin preferably contains acetoacetyl group-containing PVA. In this case, the adhesion between the polarizer and the optical film (acrylic resin film) is improved, and the durability of the polarizing plate is improved.

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

  The acetoacetyl group-containing PVA can be obtained, for example, by reacting PVA and diketene by an arbitrary method. A specific example is a method of adding diketene to a dispersion in which PVA is dispersed in a solvent such as acetic acid; a method of adding diketene to a solution in which PVA is dissolved in a solvent such as dimethylformamide or dioxane; and diketene gas to PVA. Or it is the method of making liquid diketene contact directly.

  The degree of acetoacetyl group modification in the acetoacetyl group-containing PVA is typically 0.1 mol% or more, preferably 0.1 to 40 mol%, more preferably 1 to 20%, and still more preferably 2 to 2 mol%. 7 mol%. When the degree of modification is less than 0.1 mol%, the effect of modification (for example, improvement in water resistance) may be insufficient. If the degree of modification exceeds 40 mol%, the water resistance is not improved further. The degree of acetoacetyl modification of PVA can be measured by NMR.

  The adhesive composition may contain a crosslinking agent. Although a crosslinking agent is not limited, It is a compound which has at least two functional groups which show the reactivity with respect to PVA-type resin. Crosslinking agents include, for example, ethylenediamine, triethylenediamine, hexamethylenediamine and other alkylenediamines having an alkylene group and two amino groups; tolylene diisocyanate, hydrogenated tolylene diisocyanate, trimethylolpropane tolylene diisocyanate adduct, triphenylmethane Isocyanates such as triisocyanate, methylenebis (4-phenylmethane triisocyanate), isophorone diisocyanate, and ketoxime block or phenol block thereof; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin Triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylo Epoxy such as rupropane triglycidyl ether, diglycidyl aniline, diglycidyl amine; monoaldehyde such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde; glyoxal, malondialdehyde, succindialdehyde, glutardialdehyde, maleindialdehyde, phthalate Dialdehydes such as dialdehyde; amino-formaldehyde resins such as methylol urea, methylol melamine, alkylated methylol urea, alkylated methylol melamine, acetoguanamine, condensate of benzoguanamine and formaldehyde; sodium, potassium, magnesium, calcium, aluminum, Salts and oxides of monovalent to trivalent metals such as iron and nickel. Of these, amino-formaldehyde resin and dialdehyde are preferable as the crosslinking agent. The amino-formaldehyde resin preferably has a methylol group, and methylol melamine is preferred. The dialdehyde is preferably glyoxal.

  The compounding quantity of the crosslinking agent in an adhesive composition can be suitably set according to the kind of PVA-type resin. Typically, it is about 10 to 60 parts by weight with respect to 100 parts by weight of the PVA resin, and preferably 20 to 50 parts by weight. In this range, good adhesion can be obtained. When the amount of the crosslinking agent is excessively large, the reaction via the crosslinking agent proceeds in a short time, and thus the adhesive composition tends to gel. For this reason, the pot life (pot life) as an adhesive composition becomes extremely short, and industrial use may become difficult.

  The adhesive composition may contain a metal compound colloid. The metal compound colloid may be a colloid in which particles of a metal compound are dispersed in a dispersion medium. The metal compound colloid can be a permanent colloid due to electrostatic stabilization due to mutual repulsion of the same type of charge that the particles have. By including the metal compound colloid in the adhesive composition, for example, the stability of the adhesive composition is improved even when the amount of the crosslinking agent is large.

  The average particle diameter of the colloidal particles in the metal compound colloid can be set within a range that does not adversely affect the optical characteristics (for example, polarization characteristics) of the polarizing plate. The average particle size of the colloidal particles is preferably 1 to 100 nm, and more preferably 1 to 50 nm. In these ranges, the colloidal particles can be uniformly dispersed in the adhesive layer. Thereby, adhesiveness is ensured and occurrence of knick defects is suppressed. When a knick defect occurs, for example, light leakage occurs in an image display device incorporating the polarizing plate.

  The metal compound is not limited, for example, oxides such as alumina, silica, zirconia, and titania; metal salts such as aluminum silicate, calcium carbonate, magnesium silicate, zinc carbonate, barium carbonate, calcium phosphate; celite, talc, clay, It is a mineral such as kaolin. A metal compound colloid having a positive charge is preferred. The metal compound that becomes a positively charged colloid 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 solid content concentration in the colloidal solution is typically about 1 to 50% by weight, and preferably 1 to 30% by weight. The colloidal solution may contain an acid such as nitric acid, hydrochloric acid or acetic acid as a stabilizer.

  The compounding amount of the metal compound colloid in the adhesive composition (in terms of solid content) is preferably 200 parts by weight or less, more preferably 10 to 200 parts by weight, and further preferably 20 to 175 parts by weight with respect to 100 parts by weight of the PVA resin. Preferably, 30 to 150 parts by weight are particularly preferable. In these ranges, the occurrence of nick defects is further suppressed while the adhesiveness of the adhesive composition is more reliable.

  The adhesive composition includes a coupling agent such as a silane coupling agent and a titanium coupling agent; various tackifiers; an ultraviolet absorber; an antioxidant; a stabilizer such as a heat stabilizer and a hydrolysis stabilizer. You may go out.

  The adhesive composition is preferably an aqueous solution (resin solution). The concentration of the resin in the aqueous solution is preferably from 0.1 to 15% by weight, and more preferably from 0.5 to 10% by weight, from the viewpoint of the coating property and the standing stability of the composition. The viscosity of the aqueous solution is preferably 1 to 50 mPa · s. When the adhesive composition contains a metal compound colloid, even if the viscosity is as low as 1 to 20 mPa · s, generation of nick defects is effectively suppressed. 2-6 are preferable, as for pH of aqueous solution, 2.5-5 are more preferable, 3-5 are more preferable, and 3.5-4.5 are especially preferable. In general, the surface charge of the metal compound colloid is adjusted by adjusting the pH of the aqueous solution. The surface charge is preferably a positive charge. Due to the positive charge, the occurrence of knick defects is further suppressed. The surface charge of the metal compound colloid can be confirmed, for example, by measuring the zeta potential with a zeta potential measuring device.

  The adhesive composition which is an aqueous solution (resin solution) can be formed by a known method. When the adhesive composition contains a cross-linking agent and a metal compound colloid, for example, a method of mixing the metal compound colloid in a solution in which a PVA resin and a cross-linking agent are mixed and adjusted to an appropriate concentration can be used. After mixing the PVA-based resin and the metal compound colloid, the cross-linking agent may be mixed in consideration of the use time of the adhesive composition. The concentration of the aqueous solution can be adjusted after preparing the aqueous solution.

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

[Image display device]
The image display device of the present invention includes the optical film of the present invention and / or the optical member of the present invention. The image display device is, for example, an electroluminescence (EL) display panel, a plasma display panel (PDP), a field emission display (FED), or an LCD.

  The configuration of the image display device including the optical film of the present invention (image display device of the present invention) is not particularly limited, and members such as a power source, a backlight unit, and an operation unit may be appropriately provided as necessary.

  FIG. 2 shows an example of the structure of the image display unit in the image display apparatus of the present invention. An image display unit 11 shown in FIG. 2 is an image display unit of an LCD, and includes a liquid crystal cell 4, a pair of polarizing plates 9a and 9b arranged so as to sandwich the liquid crystal cell 4, and the liquid crystal cell 4 and the polarizing plate 9a. , 9b, and a backlight 8 arranged on one surface of the laminate. Each polarizing plate 9a, 9b includes a polarizer 6a, 6b and a pair of polarizer protective films 5a, 5b, 5c, 5d arranged so as to sandwich the polarizer. The liquid crystal cell 4 has a known structure, and includes, for example, a liquid crystal layer, a glass substrate, a transparent electrode, an alignment film, and the like. The backlight 8 has a known structure, and includes, for example, a light source, a reflection sheet, a light guide plate, a diffusion plate, a diffusion sheet, a prism sheet, and a brightness enhancement film.

  In the image display unit 11, for example, at least one selected from four polarizer protective films 5a to 5d is the optical film of the present invention. All the polarizer protective films may be the optical film of the present invention. The image display unit 11 may further include an arbitrary optical film such as a retardation film or an optical compensation film and an optical member as necessary, and the optical film is the optical film of the present invention. The member may include the optical film of the present invention.

[Method for producing optical film]
In the production method of the present invention, the surface of the acrylic resin film is coated with an easy-adhesion composition containing fine particles to form a coating film of the composition (coating process), and the formed coating film is dried, Forming an easy-adhesion layer containing the fine particles on the surface (drying step). The average primary particle size of the fine particles contained in the easy-adhesion composition exceeds 200 nm, and the particle size distribution is 1.0 to 1.4. In the manufacturing method of this invention, the optical film (optical film of this invention) comprised from the acrylic resin film in which the easily bonding layer containing the said microparticles | fine-particles was formed on the surface is formed. The easy adhesion layer contains the resin contained in the easy adhesion composition.

  In the coating step, a coating film of the easy adhesion composition is formed on at least one surface of the acrylic resin film. Typically, the coating film is formed on one surface of the acrylic resin film.

  A known method can be applied to the method of applying the easy-adhesion composition in the application step. Examples of the method include a bar coating method, a roll coating method, a gravure coating method, a rod coating method, a slot orifice coating method, a curtain coating method, and a fountain coating method. The thickness of the coating film formed in the coating step can be appropriately adjusted according to the thickness required when the coating film becomes an easy-adhesion layer.

It is preferable that the surface to which the easily bonding composition in an acrylic resin film is apply | coated is surface-treated. The surface treatment is as described above, but corona discharge treatment and plasma treatment are preferred. The conditions for the corona discharge treatment are not limited. Electron irradiation amount of the corona discharge treatment is preferably 50~150W / m ² / min, 70~100W / m ² / min is more preferred.

  What is necessary is just to follow a well-known method for a drying process. The drying temperature is typically 50 ° C. or higher, preferably 90 ° C. or higher, and more preferably 110 ° C. or higher. By setting the drying temperature within these ranges, for example, an optical film excellent in color resistance (particularly in an environment of high temperature and high humidity) can be obtained. The upper limit of the drying temperature is preferably 200 ° C. or lower, and more preferably 180 ° C. or lower.

  When producing an optical film that is a stretched film from an unstretched acrylic resin film by the production method of the present invention, and when producing an optical film that is a biaxially stretched film from a uniaxially stretched acrylic resin film, these acrylics are used. It is necessary to stretch the resin film at some point. The acrylic resin film may be stretched before the easy-adhesion layer is formed or after the easy-adhesion layer is formed. The formation of the easy-adhesion layer and the stretching of the acrylic resin film can be performed simultaneously.

  The acrylic resin film may be stretched according to a known method. Stretching is, for example, uniaxial stretching or biaxial stretching. The uniaxial stretching is typically free end uniaxial stretching in which the change in the width direction (TD direction) of the acrylic resin film is free. The fixed end uniaxial stretching which fixed the change of the width direction of the acrylic resin film may be sufficient. The biaxial stretching is typically sequential biaxial stretching, but simultaneous biaxial stretching in which longitudinal and transverse stretching are simultaneously performed can also be suitably used. Furthermore, the film roll may be stretched in an oblique direction. In the present specification, stretching in the flow direction (MD direction) of the acrylic resin film is referred to as longitudinal stretching, and stretching in the width direction (TD direction) is referred to as lateral stretching. In the case of a strip-shaped acrylic resin film, the MD direction is the longitudinal direction of the film.

  A known stretching machine can be used for stretching the acrylic resin film. The longitudinal stretching machine is not particularly limited, but an oven stretching machine is preferable. The oven vertical stretching machine is generally composed of an oven and transport rolls provided on the inlet side and the outlet side of the oven, respectively. The resin film is stretched in the transport direction by giving a peripheral speed difference between the transport roll on the entrance side of the oven and the transport roll on the exit side. The transverse stretching machine is not particularly limited, but a tenter stretching machine is preferable. The tenter stretching machine may be either a grip type or a pin type, but the grip type is preferable because the resin film hardly tears. A grip-type tenter stretching machine is generally composed of a clip traveling device for transverse stretching and an oven. In the clip traveling device, the resin film is conveyed in a state where the lateral end of the resin film is sandwiched between the clips. At this time, the resin rail is stretched laterally by opening the guide rail of the clip traveling device and widening the distance between the left and right two rows of clips. In the grip-type tenter stretching machine, simultaneous biaxial stretching is also possible by providing a clip expansion / contraction function with respect to the transport direction of the resin film. Moreover, the diagonal stretcher | stretcher which carries out the tension | pulling stretching in the conveyance direction of the said film at a different speed on the right and left of the extending direction of the resin film may be used.

  The stretching temperature is preferably in the vicinity of Tg of the acrylic resin constituting the acrylic resin film. Specifically, the range of Tg-30 ° C to Tg + 100 ° C is preferable, and the range of Tg-20 ° C to Tg + 80 ° C is more preferable. When the stretching temperature is lower than Tg-30 ° C, a sufficient stretching ratio may not be ensured. If the stretching temperature exceeds Tg + 100 ° C., the resin constituting the film may flow and stable stretching may not be performed.

  The draw ratio defined by the area ratio is preferably 1.1 to 25 times, more preferably 1.3 to 10 times. When the draw ratio is less than 1.1 times, the optical film characteristics expected by stretching, for example, toughness, may not be realized. On the other hand, when the draw ratio exceeds 25 times, the effect of improving the properties of the optical film is usually not obtained any more.

  The stretching speed is preferably 10 to 20,000% / min, more preferably 100 to 10,000% / min for stretching in one direction. When the stretching speed is less than 10% / min, the time required for stretching the film becomes excessively long, and the production cost of the optical film may increase. If the stretching speed exceeds 20,000% / min, the film may break.

  When forming an easily bonding layer and extending | stretching an acrylic resin film simultaneously, what is necessary is just to extend | stretch the acrylic resin film in which the coating film of the easily bonding composition was formed in a heating atmosphere after an application | coating process, for example. Due to the heat applied to the film for stretching, the coating film of the easy-adhesive composition formed on the surface of the acrylic resin film is dried to form an easy-adhesive layer. In addition, since Tg of an acrylic resin film is 100 degreeC or more normally, the extending | stretching temperature mentioned above is high enough for an easily bonding layer to be formed from the coating film of an easily bonding composition.

  The acrylic resin film that forms the coating film of the easy-adhesive composition in the coating step may be an unstretched film or a stretched film that has already been stretched. When the acrylic resin film that forms the coating film is a strip-shaped uniaxially stretched film and an optical film that is a biaxially stretched film is manufactured, the direction of uniaxial stretching is the MD direction of the film, and after the coating film is formed The stretching direction is preferably the TD direction. Thereby, an efficient optical film can be manufactured.

  When forming an acrylic resin film by melt extrusion, the process from formation of an acrylic resin film to obtaining an optical film which is a stretched film can be continuously performed. In this case, it is preferable to perform continuously the process of apply | coating an easily bonding composition to the surface of an acrylic resin film, and the process of extending | stretching the acrylic resin film which apply | coated the easily bonding composition in a heating atmosphere. Such an easy-adhesion composition coating step that is continuously performed is referred to as in-line coating. When producing an optical film that is a biaxially stretched film by the production method of the present invention, a step of stretching an unstretched film to make an acrylic resin film that is a uniaxially stretched film, an easily adhesive composition on the surface of the acrylic resin film It is particularly preferable to continuously perform the step of coating and the step of stretching the acrylic resin film coated with the easy-adhesive composition in a heated atmosphere. Furthermore, when performing surface treatments such as corona discharge treatment and plasma treatment on the acrylic resin film, a step of drawing an unstretched film to obtain an acrylic resin film that is a uniaxially stretched film, the surface of the acrylic resin film being a surface The process of processing, the process of apply | coating an easily bonding composition to the said surface of the surface-treated acrylic resin film, and the process of extending | stretching the acrylic resin film which apply | coated the easily bonding composition in a heating atmosphere are performed continuously. preferable.

  The production method of the present invention may include any step other than the steps described above as long as the effect of the present invention is obtained. This step is, for example, a step of laminating a further layer (for example, a resin layer) on the formed optical film, or a step of performing post-processing such as coating treatment or surface treatment on the formed optical film.

  Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to the following examples.

  Initially, the evaluation method of the polymer, the optical film, and the optical film roll which were produced in the present Example is shown.

[Weight average molecular weight]
The weight average molecular weight of the polymer was determined in terms of polystyrene using gel permeation chromatography (GPC). The apparatus and measurement conditions used for the measurement are as follows.
System: Tosoh GPC system HLC-8220
Measurement side column configuration ・ Guard column: Tosoh, TSKguardcolumn SuperHZ-L
・ Separation column: Tosoh, TSKgel SuperHZM-M 2 series connection Reference column configuration ・ Reference column: Tosoh, TSKgel SuperH-RC
Developing solvent: Chloroform (Wako Pure Chemical Industries, special grade)
Flow rate of developing solvent: 0.6 mL / min Standard sample: TSK standard polystyrene (manufactured by Tosoh, PS-oligomer kit)
Column temperature: 40 ° C

[Glass transition temperature (Tg)]
The Tg of the polymer was determined by the starting point method in accordance with JIS K7121 regulations. Specifically, a differential scanning calorimeter (manufactured by Rigaku, DSC-8230) is used, and a sample of about 10 mg is heated from normal temperature to 200 ° C. (temperature increase rate: 20 ° C./min) in a nitrogen gas atmosphere. The DSC curve was evaluated. Α-alumina was used as a reference.

[Film thickness]
The thickness of the film was measured using a Digimatic micrometer (manufactured by Mitutoyo Corporation). Thereafter, a sample for measuring and evaluating the physical properties of the film including the physical properties indicating the evaluation method was obtained from the central portion in the width direction of the film.

[Average particle size and particle size distribution of fine particles]
The average particle size and particle size distribution of the fine particles were evaluated using a particle size distribution measuring device (Submicron Particle Sizer NICOMP380, manufactured by Particle Sizing Systems). Specifically, for the fine particles in a state dispersed in water, the equivalent spherical distribution in the range of 100 nm or more in terms of the primary particle diameter is measured by the measuring device, and the obtained distribution is integrated from the large particle side. The particle diameter of the particles having an integrated volume fraction of 50% was determined and used as the average primary particle diameter (d50) of the fine particles. Separately from this, the particle diameter (d25) of particles having an integrated volume fraction of 25% and the particle diameter (d75) of 75% accumulated from the large particle side in the distribution are obtained, and the ratio (d25 / d75) Was the particle size distribution of the fine particles.

[Haze ratio]
The haze ratio of the produced optical film was evaluated by a haze meter (Nippon Denshoku Industries Co., Ltd., NDH-1001DP).

[Stability of roll quality (blocking resistance of optical film)]
The blocking resistance of the produced optical film was evaluated as follows. The produced optical film was wound around a roll to form a film roll, which was then left for 24 hours. After leaving, the film roll was visually confirmed, and the optical film was fed out from the film roll, and the surface was visually confirmed over the entire length of the film to evaluate blocking resistance. The evaluation criteria are as follows.
○: Deformation of the film roll and wrinkle of the film were not observed.
X: Deformation of the film roll or wrinkle of the film was confirmed.

(Production Example 1)
In a 1000 L reaction kettle equipped with a stirrer, temperature sensor, cooling pipe and nitrogen introduction pipe, 40 parts by weight of methyl methacrylate (MMA), 10 parts by weight of 2- (hydroxymethyl) methyl acrylate (MHMA), polymerization As solvents, 50 parts by weight of toluene and 0.025 parts by weight of an antioxidant (ADK STAB 2112, manufactured by ADEKA) were charged, and the temperature was raised to 105 ° C. while nitrogen was passed through the solvent. When the reflux accompanying the temperature rise began, 0.05 parts by weight of t-amylperoxyisononanoate (Arkema Yoshitomi, trade name: Luperox 570) was added as a polymerization initiator, and the t-amylperoxyisononoate was added. While 0.10 parts by weight of nanoate was added dropwise over 3 hours, solution polymerization was allowed to proceed under reflux at about 105 to 110 ° C., followed by further aging for 4 hours.

  Next, 0.05 parts by weight of 2-ethylhexyl phosphate (Phoslex A-8, manufactured by Sakai Chemical Industry Co., Ltd.) is added to the resulting polymerization solution as a catalyst for the cyclization condensation reaction (cyclization catalyst). The cyclization condensation reaction for forming a lactone ring structure was allowed to proceed for 2 hours under reflux at 110 ° C. Next, the obtained polymerization solution was heated to 240 ° C. using an autoclave, and the cyclization condensation reaction was further advanced at the temperature.

Next, the obtained polymerization solution was subjected to a barrel temperature of 240 ° C., a rotation speed of 100 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1 and a forevent number of 4 (first and 2, a third and a fourth vent), a side feeder is provided between the third vent and the fourth vent, and a leaf disk type polymer filter (filtration accuracy 5 μm, filtration area 1.5 m at the tip) ² ) was introduced into a vent type screw twin screw extruder (φ = 50.0 mm, L / D = 30) at a processing rate of 45 kg / hour (resin amount conversion) to perform devolatilization. At that time, a separately prepared mixed solution of antioxidant / cyclization catalyst deactivator was charged at a rate of 0.68 kg / hour after the first vent, and then ion-exchanged water was charged at 0.22 kg / hour. After the second and third vents at the speed, respectively, was charged. In the mixed solution of the antioxidant / cyclization catalyst deactivator, 50 parts by weight of an antioxidant (manufactured by Ciba Specialty Chemicals, Irganox 1010) and 35 parts by weight of zinc octylate (Nippon Chemical Industry Co., Ltd.) Manufactured by Nikka Octics Zinc (3.6% by weight) was dissolved in 200 parts by weight of toluene. In addition, at the time of devolatilization, pellets of styrene-acrylonitrile copolymer (AS resin: ratio of styrene unit / acrylonitrile unit is 73% by weight / 27% by weight, weight average molecular weight is 220,000) from the side feeder. And 15 kg / hour.

  After completion of devolatilization, the resin in the molten state remaining in the extruder is discharged while filtering through a polymer filter from the tip of the extruder, pelletized by a pelletizer, and has a lactone ring structure in the main chain (meta) An acrylic resin transparent pellet (1A) containing an acrylic polymer as a main component (content: 75% by weight) and further containing a styrene-acrylonitrile copolymer at a content of 25% by weight was obtained. The acrylic resin constituting the pellet (1A) had a Tg of 122 ° C. and a weight average molecular weight of 151,000.

  Next, the produced pellet (1A) was melt-extruded at 280 ° C. using a single screw extruder (φ = 20.0 mm, L / D = 25) and a coat hanger type T die (width 150 mm). A 100 μm acrylic resin film was formed. At the time of melt extrusion, the resin film was discharged from the T die onto a cooling roll maintained at 110 ° C.

  Next, using the biaxial stretching machine (TYPE EX4, manufactured by Toyo Seiki Seisakusho Co., Ltd.), the produced acrylic resin film is freely stretched in the MD direction (flow direction, extrusion direction) at a stretching ratio of 2.0 times and a stretching temperature of 140 ° C. End-uniaxial stretching was performed to obtain a stretched acrylic resin film (F1).

(Production Example 2)
In a 100 L stainless steel polymerization tank equipped with a submerged tank and a stirrer, 42.5 parts by weight of MMA, 5 parts by weight of N-phenylmaleimide (PMI), 0.5 part by weight of styrene (St), toluene as a polymerization solvent 50 parts by weight, 0.2 part by weight of acetic anhydride as an organic acid, and 0.06 part by weight of n-dodecyl mercaptan were charged as a chain transfer agent, and nitrogen gas was bubbled for 10 minutes while stirring at 100 rpm. . Next, the temperature was raised while keeping the inside of the tank in a nitrogen atmosphere, and when the temperature in the tank reached 100 ° C., 0.075 parts by weight of t-butylperoxyisopropyl carbonate was added. Nitrogen bubbling was started in the bath. Next, a mixture of 2 parts by weight of styrene and 0.075 part by weight of t-butyl peroxyisopropyl carbonate was added to the tank at a constant rate over 5 hours while refluxing at a polymerization temperature of 105 to 110 ° C. The polymerization reaction was allowed to proceed for 15 hours.

  Next, 9,10-dihydro-9-oxa-10-phosphanenanthrene-10-oxide (manufactured by Sanko Co., Ltd., HCA) and phenol as a phosphoric acid-based antioxidant were added to the obtained polymerization solution. 0.1 wt. Of pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] (AO-60, manufactured by Asahi Denka Co., Ltd.) as a system antioxidant Parts and 0.02 parts by weight were added.

  Next, the polymerization solution to which the antioxidant was added was converted into a vent type screw having a barrel temperature of 240 ° C., a rotation speed of 100 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1, and a forevent number of 4. It introduce | transduced into the axial extruder ((PHI) = 29.75mm, L / D = 30) at the processing speed of 2.0 kg / hour (resin amount conversion). Next, the resin in the hot melt state in the extruder is discharged from the tip of the extruder, pelletized by a pelletizer, and a transparent acrylic resin made of a (meth) acrylic polymer having an N-substituted maleimide structure in the main chain. A pellet (2A) was obtained. The acrylic resin constituting the pellet (2A) had a Tg of 138 ° C. and a weight average molecular weight of 20 million.

  Next, the produced pellet (2A) was melt-extruded at 280 ° C. using a single screw extruder (φ = 20.0 mm, L / D = 25) and a coat hanger type T die (width 150 mm). A 100 μm acrylic resin film was formed. At the time of melt extrusion, the resin film was discharged from the T die onto a cooling roll maintained at 110 ° C.

  Next, using the biaxial stretching machine (TYPE EX4, manufactured by Toyo Seiki Seisakusho Co., Ltd.), the produced acrylic resin film is freely stretched at a stretching ratio of 2.0 times and a stretching temperature of 155 ° C. in the MD direction (flow direction, extrusion direction). End-uniaxial stretching was performed to obtain a stretched acrylic resin film (F2).

(Production Example 3)
Single-screw extruder (φ = 20 mm, L / D = 25) and coat with acrylic resin (Rohm and Haas, KAMAX T-240) mainly composed of (meth) acrylic polymer having glutarimide structure in the main chain An acrylic resin film having a thickness of 100 μm was formed by melt extrusion at 280 ° C. using a hanger type T die (width 150 mm). At the time of melt extrusion, the resin film was discharged from the T die onto a cooling roll maintained at 110 ° C.

  Next, using the biaxial stretching machine (TYPE EX4, manufactured by Toyo Seiki Seisakusho Co., Ltd.), the produced acrylic resin film is freely stretched in the MD direction (flow direction, extrusion direction) at a stretching ratio of 2.0 times and a stretching temperature of 140 ° C. End-uniaxial stretching was performed to obtain a stretched acrylic resin film (F3).

(Production Example 4)
The same as Production Example 3 except that an acrylic resin (Sumitex B-TR, Sumitomo Chemical Co., Ltd.) mainly composed of a (meth) acrylic polymer having a glutaric anhydride structure in the main chain was used instead of KAMAX T-240. Thus, a stretched acrylic resin film (F4) was obtained.

(Production Example 5)
Instead of KAMAX T-240, the same procedure as in Production Example 3 was used except that an acrylic resin (manufactured by Asahi Kasei Chemicals, Delpet 980N) having a (meth) acrylic polymer having a maleic anhydride structure in the main chain as a main component was used. Thus, a stretched acrylic resin film (F5) was obtained.

(Production Example 6)
In a pressure-resistant reaction vessel equipped with a stirrer, 70 parts by weight of deionized water, 0.5 parts by weight of sodium pyrophosphate, 0.2 parts by weight of potassium oleate, 0.005 parts by weight of ferrous sulfate, 0.2 parts by weight of dextrose A reaction mixture consisting of 0.1 parts by weight of p-menthane hydroperoxide and 28 parts by weight of 1,3-butadiene was charged, and the temperature was raised to 65 ° C. to advance the polymerization reaction. When 2 hours have elapsed from the start of polymerization, 0.2 parts by weight of p-hydroperoxide is further added to the mixture, and 72 parts by weight of 1,3-butadiene, 1.33 parts by weight of potassium oleate and deionized water are added. 75 parts by weight were continuously added dropwise over 2 hours. Thereafter, the polymerization reaction was continued, and a latex of a butadiene rubber polymer having an average particle diameter of 0.240 μm was obtained by polymerization for 21 hours from the start of polymerization.

  Next, in a polymerization vessel equipped with a cooler and a stirrer, 120 parts by weight of deionized water, 50 parts by weight (solid content) of the prepared butadiene rubber polymer latex, 1.5 parts by weight of potassium oleate and sodium formaldehyde 0.6 parts by weight of sulfoxylate (SFS) was added, and the inside of the container was sufficiently replaced with nitrogen gas. Next, after raising the temperature in the container to 70 ° C., a mixed monomer solution composed of 36.5 parts by weight of styrene and 13.5 parts by weight of acrylonitrile, 0.27 parts by weight of cumene hydroxyperoxide and 20 deionized water. The polymerization reaction was allowed to proceed while continuously dropping the polymerization initiator solution consisting of parts by weight into the container over 2 hours. After completion of the dropping, the temperature in the container was raised to 80 ° C., and the polymerization reaction was continued for another 2 hours. Next, after the temperature in the container was lowered to 40 ° C., the contents were passed through a 300-mesh wire mesh to obtain an emulsion polymerization liquid of elastic organic fine particles.

  The obtained emulsion polymer solution of elastic organic fine particles is salted out and coagulated with calcium chloride, and the solidified product is washed with water and dried to obtain powdered elastic organic fine particles (G1: average particle size 0.260 μm, soft polymer). A refractive index of the layer of 1.516) was obtained.

  Next, an acrylic resin (manufactured by Asahi Kasei Chemicals Corp., Delpet 980N) having a maleic anhydride structure in the main chain as a main component and the produced elastic organic fine particles (G1) are acrylic resin. The mixture was kneaded using a twin-screw extruder so that / elastic organic fine particles = 90/10 (weight ratio) to produce pellets (3A). Next, the produced pellet (3A) was melt-extruded at 280 ° C. using a single screw extruder (φ = 20.0 mm, L / D = 25) and a coat hanger type T die (width 150 mm). A 100 μm acrylic resin film was formed. At the time of melt extrusion, the resin film was discharged from the T die onto a cooling roll maintained at 110 ° C.

  Next, using the biaxial stretching machine (TYPE EX4, manufactured by Toyo Seiki Seisakusho Co., Ltd.), the produced acrylic resin film is freely stretched in the MD direction (flow direction, extrusion direction) at a stretching ratio of 2.0 times and a stretching temperature of 140 ° C. End-uniaxial stretching was performed to obtain a stretched acrylic resin film (F6).

(Production Example 7)
Urethane resin (Daiichi Kogyo Seiyaku Co., Ltd., Superflex 210, solid content 35% by weight), emulsion containing amorphous silica fine particles (Nippon Shokubai Co., Ltd., Seahoster KE-W30, average particle size (primary particle size) 0.28 μm 0.09 part by weight, particle size distribution 1.1, solid content 20% by weight) and 80 parts by weight of pure water were mixed to obtain an easy-adhesion composition (1B) which is an emulsion-like dispersion.

(Production Example 8)
Emulsion containing urethane resin (Mitsui Chemical Polyurethane, Takelac W-5030, solid content 30% by weight) 18 parts by weight, amorphous silica fine particles (Nippon Shokubai Co., Ltd., Seahoster KE-W30, average particle size (primary particle size) 0.28 μm , Particle size distribution 1.1, solid content 20% by weight) 0.08 part by weight and 72 parts by weight of pure water were mixed to obtain an easy-adhesion composition (2B) which is an emulsion-like dispersion.

(Production Example 9)
14 parts by weight of urethane resin (made by DIC, Hydran CP-7020, solid content 40% by weight), emulsion containing amorphous silica fine particles (manufactured by Nippon Shokubai Co., Ltd., Seahoster KE-W30, average particle size (primary particle size) 0.28 μm, particle size (Distribution 1.1, solid content 20% by weight) 0.07 part by weight and 66 parts by weight of pure water were mixed to obtain an easy-adhesion composition (3B) as an emulsion-like dispersion.

(Production Example 10)
Urethane resin (Daiichi Kogyo Seiyaku Co., Ltd., Superflex 620, solid content 30% by weight), emulsion containing amorphous silica fine particles (Nippon Shokubai Co., Ltd., Seahoster KE-W30, average particle size (primary particle size) 0.28 μm , Particle size distribution 1.1, solid content 20% by weight) 0.30 part by weight and 66 parts by weight of pure water were mixed to obtain an easy-adhesion composition (4B) as an emulsion dispersion.

(Production Example 11)
20 parts by weight of urethane resin (Daiichi Kogyo Seiyaku Co., Ltd., Superflex 210, solid content 35% by weight), emulsion containing amorphous silica fine particles (average particle size (primary particle size) 0.28 μm, particle size distribution 1.7, solid content 19% by weight) 0.09 part by weight and 80 parts by weight of pure water were mixed to obtain an easy-adhesion composition (5B) as an emulsion dispersion.

(Production Example 12)
Urethane resin (Daiichi Kogyo Seiyaku Co., Ltd., Superflex 210, solid content 35% by weight), emulsion containing amorphous silica fine particles (Nippon Shokubai Co., Ltd., Seahoster KE-W10, average particle size (primary particle size) 0.11 μm , Particle size distribution 1.1, solid content 15% by weight) 0.12 parts by weight and 80 parts by weight of pure water were mixed to obtain an easy-adhesion composition (6B) as an emulsion-like dispersion.

(Production Example 13)
19 parts by weight of urethane resin (Daiichi Kogyo Seiyaku Co., Ltd., Superflex 210, solid content 35% by weight), 1.3 parts by weight of cross-linking agent (manufactured by Nippon Shokubai, Epocross WS-700, solid content 25% by weight), amorphous silica fine particles 0.09 part by weight of an emulsion (Nippon Shokubai Co., Ltd., Seahoster KE-W30, average particle size (primary particle size) 0.28 μm, particle size distribution 1.1, solid content 20% by weight) and 79 parts by weight of pure water Thus, an easy-adhesion composition (7B) which is an emulsion-like dispersion was obtained.

(Production Example 14)
Includes 19 parts by weight of urethane resin (manufactured by DIC, Hydran AP-40N, solid content 35% by weight), 1.3 parts by weight of cross-linking agent (manufactured by Nippon Shokubai, Epocross WS-700, solid content 25% by weight), and amorphous silica fine particles Mixing 0.09 part by weight of emulsion (Nippon Shokubai Co., Ltd., Seahoster KE-W30, average particle size (primary particle size) 0.28 μm, particle size distribution 1.1, solid content 20% by weight) and 79 parts by weight of pure water The easy-adhesion composition (8B) which is an emulsion-like dispersion was obtained.

Example 1
The easy-adhesive composition (1B) produced in Production Example 7 is applied to one main surface of the stretched acrylic resin film (F1) produced in Production Example 1 so that the thickness of the coating film after drying is 270 nm. After coating using an engineering tester, the whole was dried at 100 ° C. for 2 minutes. Thus, the optical film comprised from the acrylic resin film in which the easily bonding layer containing a urethane resin and microparticles | fine-particles was formed in one main surface was obtained. The fine particles contained in the formed easy-adhesion layer retained the shape in the easy-adhesion composition (1B).

(Example 2)
Instead of the easy-adhesive composition (1B), an easy-adhesive layer containing urethane resin and fine particles is one of the main components in the same manner as in Example 1 except that the easy-adhesive composition (2B) prepared in Production Example 8 was used. An optical film composed of an acrylic resin film formed on the surface was obtained.

(Example 3)
Instead of the stretched acrylic resin film (F1), an easy-adhesion layer containing a urethane resin and fine particles is one of the main components in the same manner as in Example 1 except that the stretched acrylic resin film (F2) produced in Production Example 2 was used. An optical film composed of an acrylic resin film formed on the surface was obtained.

Example 4
Instead of the stretched acrylic resin film (F1), an easy-adhesion layer containing a urethane resin and fine particles is one of the main components in the same manner as in Example 1 except that the stretched acrylic resin film (F3) produced in Production Example 3 was used. An optical film composed of an acrylic resin film formed on the surface was obtained.

(Example 5)
Instead of the stretched acrylic resin film (F1), the stretched acrylic resin film (F4) produced in Production Example 4 was used, and instead of the easy adhesion composition (1B), the easy adhesion composition produced in Production Example 9 ( An optical film composed of an acrylic resin film in which an easy-adhesion layer containing a urethane resin and fine particles was formed on one main surface was obtained in the same manner as in Example 1 except that 3B) was used.

(Example 6)
Instead of the stretched acrylic resin film (F1), the stretched acrylic resin film (F5) produced in Production Example 5 was used, and instead of the easy adhesion composition (1B), the easy adhesion composition produced in Production Example 10 ( An optical film composed of an acrylic resin film in which an easy-adhesion layer containing a urethane resin and fine particles was formed on one main surface was obtained in the same manner as in Example 1 except that 4B) was used.

(Example 7)
The easy-adhesion composition (1B) produced in Production Example 7 is applied to one main surface of the stretched acrylic resin film (F1) produced in Production Example 1 so that the thickness of the coating film after drying is 600 nm. After coating using an engineering tester, the whole was dried at 100 ° C. for 2 minutes. Next, the film obtained in this way is TD direction (direction perpendicular to MD direction in the film plane, width direction at the time of extrusion molding) using a biaxial stretching machine (manufactured by Toyo Seiki Seisakusho, TYPE EX4). It is composed of an acrylic resin film, which is a biaxially stretched film, in which an easy-adhesion layer containing a urethane resin and fine particles is formed on one main surface by uniaxial stretching at a stretching ratio of 1.5 times and a stretching temperature of 140 ° C. An optical film was obtained.

(Example 8)
Instead of the stretched acrylic resin film (F1), an easy-adhesion layer containing a urethane resin and fine particles is one of the main components in the same manner as in Example 1 except that the stretched acrylic resin film (F6) produced in Production Example 6 was used. An optical film composed of an acrylic resin film formed on the surface was obtained.

(Comparative Example 1)
In the same manner as in Example 1 except that the easy-adhesive composition (5B) produced in Production Example 11 was used instead of the easy-adhesive composition (1B), an easy-adhesive layer containing a urethane resin and fine particles was one of the main components. An optical film composed of an acrylic resin film formed on the surface was obtained.

(Comparative Example 2)
Instead of the easy-adhesive composition (1B), an easy-adhesive layer containing urethane resin and fine particles is one of the main components in the same manner as in Example 1 except that the easy-adhesive composition (6B) prepared in Production Example 12 was used. An optical film composed of an acrylic resin film formed on the surface was obtained.

Example 9
The acrylic resin pellet (1A) produced in Production Example 1 was used with a single-screw extruder (φ = 90.0 mm, L / D = 32) equipped with a polymer filter (filtration accuracy: 5 μm) and a T-die at the tip. The film was melt extruded at a processing speed of 200 kg / hour (resin amount conversion) and a temperature of 270 ° C. to form a 220 μm-thick belt-like film. Next, the formed film is continuously supplied to an oven longitudinal stretching machine following melt extrusion, and the stretching temperature 142 in the longitudinal direction of the film (flow direction at the time of melt extrusion, MD direction) by the stretching machine. The film was stretched (longitudinal stretching) at 1.5 ° C. and a stretching ratio of 1.5 times.

  Furthermore, the thickness of the coating film after drying the easy-adhesive composition (7B) produced in Production Example 13 on the one main surface of the acrylic resin film after longitudinal stretching by the gravure coating method is 1050 nm. After being applied (in-line coating), the acrylic resin film was supplied as it was to a tenter transverse stretching machine, and stretched in the width direction (lateral stretching) at a stretching temperature of 132 ° C. and a stretching ratio of 3.0 times. In this way, an optical film (thickness: 58 μm) composed of an acrylic resin film, which is a biaxially stretched film, has an easy-adhesion layer (thickness: 350 nm) containing a urethane resin and fine particles formed on one main surface. Obtained.

(Example 10)
Instead of the acrylic resin pellet (1A), an easy-adhesion layer containing a urethane resin and fine particles is one of the main components in the same manner as in Example 9, except that the acrylic resin pellet (2A) prepared in Production Example 2 was used. The optical film comprised from the acrylic resin film which is a biaxially stretched film formed in the surface was obtained.

(Example 11)
Implementation was carried out except that an acrylic resin (Rohm and Haas, KAMAX T-240) mainly composed of a (meth) acrylic polymer having a glutarimide structure in the main chain was used instead of the acrylic resin pellet (1A). In the same manner as in Example 9, an optical film composed of an acrylic resin film, which is a biaxially stretched film, having an easy-adhesion layer containing a urethane resin and fine particles formed on one main surface was obtained.

(Example 12)
The acrylic resin pellet (1A) produced in Production Example 1 was used with a single-screw extruder (φ = 90.0 mm, L / D = 32) equipped with a polymer filter (filtration accuracy: 5 μm) and a T-die at the tip. The film was melt extruded at a processing speed of 200 kg / hour (resin amount conversion) and a temperature of 270 ° C. to form a 220 μm-thick belt-like film. Next, the formed film is continuously supplied to an oven longitudinal stretching machine following melt extrusion, and the stretching temperature 142 in the longitudinal direction of the film (flow direction at the time of melt extrusion, MD direction) by the stretching machine. The film was stretched (longitudinal stretching) at 1.5 ° C. and a stretching ratio of 1.5 times.

  Further, after continuously subjecting one main surface of the longitudinally stretched acrylic resin film to corona treatment, the easily adhesive composition (7B) produced in Production Example 13 was dried on the treated surface by a gravure coating method. The coating film was applied so that the thickness of the coating film was 1050 nm (in-line coating). Subsequently, the acrylic resin film was supplied to the tenter transverse stretching machine as it was, and stretched in the width direction (lateral stretching) at a stretching temperature of 132 ° C. and a stretching ratio of 3.0 times. In this way, an optical film (thickness: 58 μm) composed of an acrylic resin film, which is a biaxially stretched film, has an easy-adhesion layer (thickness: 350 nm) containing a urethane resin and fine particles formed on one main surface. Obtained.

(Example 13)
Instead of the easy-adhesive composition (7B), an easy-adhesive layer containing a urethane resin and fine particles is one of the main components in the same manner as in Example 12 except that the easy-adhesive composition (8B) produced in Production Example 14 was used. The optical film comprised from the acrylic resin film which is a biaxially stretched film formed in the surface was obtained.

  The evaluation results of the optical films prepared in each example and comparative example are summarized in Table 1 below.

  As shown in Table 1, in Examples 1 to 13, optical films having high blocking resistance and high transparency were obtained. On the other hand, in Comparative Example 1, the particle size distribution of fine particles contained in the easy-adhesion composition and the easy-adhesion layer formed from the composition is 1.7, which is larger than that of the example, and the haze ratio is high (inferior in transparency). An optical film was formed. Further, in Comparative Example 2, an optical film having an average primary particle diameter of 110 nm, which is smaller than that of the example, is included in the easy-adhesion composition and the easy-adhesion layer formed from the composition, and is inferior in blocking resistance. It was. In the optical film of Comparative Example 2, when the film was wound on a film roll, wrinkles of the film and roll deformation occurred over time.

  The optical film of the present invention is suitable for use in various protective films such as polarizer protective films, retardation films and polarizing films used in image display devices such as LCDs.

DESCRIPTION OF SYMBOLS 1 Optical film 2 Acrylic resin film 3 Easy-adhesion layer 4 Liquid crystal cell 5a, 5b, 5c, 5d Polarizer protective film 6a, 6b Polarizer 8 Backlight 9a, 9b Polarizing plate 11 Image display part

Claims (6)

Consists of an acrylic resin film with an easy-adhesion layer formed on the surface,
The easy-adhesion layer contains fine particles;
The optical film whose average primary particle diameter of microparticles | fine-particles contained in the said easily bonding layer exceeds 200 nm, and a particle size distribution is 1.0-1.4.   The optical film according to claim 1, wherein the easy adhesion layer is a urethane resin layer.   The optical film according to claim 1, wherein the acrylic resin film contains a (meth) acrylic polymer having a ring structure in the main chain.   An optical member provided with the optical film in any one of Claims 1-3.   An image display apparatus provided with the optical film in any one of Claims 1-3. It is a manufacturing method of the optical film according to claim 1,
On the surface of the acrylic resin film, an easy-adhesion composition containing fine particles is applied to form a coating film of the composition,
Drying the coating film to form an easy-adhesion layer containing the fine particles on the surface;
The manufacturing method of the optical film whose average primary particle diameter of the microparticles | fine-particles contained in the said composition exceeds 200 nm, and a particle size distribution is 1.0-1.4.

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