WO2015098539A1

WO2015098539A1 - Optical film and manufacturing method therefor

Info

Publication number: WO2015098539A1
Application number: PCT/JP2014/082777
Authority: WO
Inventors: 正浩吉澤; 匡弘松本; 洋介喜多
Original assignee: 大倉工業株式会社
Priority date: 2013-12-28
Filing date: 2014-12-11
Publication date: 2015-07-02
Also published as: KR20160105390A; CN105765426B; JPWO2015098539A1; TWI629170B; JP6163564B2; KR102303580B1; TW201536548A; CN105765426A

Abstract

[Problem] To provide an optical film that adheres well to another functional film while minimizing blocking during take-up of said optical film. [Solution] An optical film characterized by having, on at least one surface of a (meth)acrylic resin film, a readily adhering layer containing both (meth)acrylonitrile-based microparticles and a urethane resin obtained by reacting a polyol with a polyisocyanate. Said optical film can be used as a polarizer-protecting film.

Description

Optical film and manufacturing method thereof

This invention relates to the optical film which has an easily bonding layer on the surface of a (meth) acrylic-type resin film, and its manufacturing method.

An acrylic resin containing a (meth) acrylic polymer typified by polymethyl methacrylate is known to have excellent optical properties such as light transmittance and excellent balance between mechanical strength and moldability. For this reason, acrylic resin is used for optical related applications in recent years, and acrylic resin is being applied to optical films incorporated in image display devices such as liquid crystal display devices, plasma display panels, and organic EL display devices. .

Optical films are often used in a state of being laminated with other functional films. For example, a polarizer protective film which is a kind of optical film is usually used in an image display device in the state of a polarizer and a polarizing plate laminated on at least one surface of the polarizer via an adhesive layer. .

When an acrylic resin is used for such 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. However, an optical film made of an acrylic resin provided with an easy-adhesion layer has a problem that blocking occurs in the step of winding on a roll.

Therefore, JP 2010-55062 A includes acrylic resin film and fine particles such as urethane resin and colloidal silica fine particles for the purpose of suppressing blocking when the optical film made of acrylic resin is wound around a roll. A polarizer protective film having an easy adhesion layer formed from an easy adhesion composition has been proposed. The surface of this easy-adhesion layer is described as being capable of reducing the frictional force at the contact surface between the acrylic resin film and the easy-adhesion layer because minute irregularities are formed on the surface.

However, an acrylic resin film formed with an easy-adhesion layer containing fine particles such as colloidal silica has unevenness on the surface of the easy-adhesion layer due to the fine particles, so that the frictional force at the contact surface between the acrylic resin film and the easy-adhesion layer is reduced. Although it can reduce and can suppress the blocking which arises at the time of winding of a film, it turned out that there exists a problem that the intensity | strength and easy adhesiveness of an easily bonding layer fall by mix | blending microparticles | fine-particles.

The present invention has been made in view of such problems, and it is an object to improve the strength and easy adhesion of an optical film composed of an acrylic resin film having an easy adhesion layer containing fine particles, It aims at providing the optical film which is excellent in adhesiveness with another functional film, suppressing the blocking produced at the time of winding of a film.

According to the present invention,
(1) It has an easy-adhesion layer containing a urethane resin obtained by reacting a polyol and a polyisocyanate and (meth) acrylonitrile-based fine particles on at least one surface of a (meth) acrylic resin film. An optical film is provided.

The present invention also provides
(2) The optical film according to (1), wherein the easy adhesion layer contains 0.1 to 15 parts by weight of the fine particles with respect to 100 parts by weight of the urethane resin.
(3) The optical film according to (1) or (2), wherein the urethane resin has an anionic functional group in the molecule,
(4) The optical film according to any one of (1) to (3), wherein the polyol is at least one selected from polyester polyol, polyacryl polyol, polyether polyol, and polycarbonate polyol,
(5) The optical film according to any one of (1) to (4), wherein the fine particles have a particle size of 50 to 350 nm.

The present invention further provides:
(6) The method for producing an optical film according to any one of (1) to (5), wherein a urethane resin and (meth) acrylonitrile-based fine particles are included on at least one surface of the (meth) acrylic resin film. Provided is a method for producing an optical film, wherein an easy-adhesive composition is applied to form a coating film, and the coating film is dried to form an easy-adhesion layer.

The optical film of the present invention has an easy-adhesion layer containing a urethane resin and (meth) acrylonitrile-based fine particles, thereby effectively suppressing blocking that occurs during winding, and the strength and easy adhesion of the easy-adhesion layer. Improved, and excellent adhesion to other functional films. In the present specification, the term “(meth) acryl” is used as a general term for methacryl, acryl or a mixture thereof. The term “(meth) acrylonitrile” is also used as a general term for methacrylonitrile, acrylonitrile, or a mixture thereof.

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 polarizing plate of this invention.

[(Meth) acrylic resin film]
The (meth) acrylic resin film used for the optical film of the present invention contains a (meth) acrylic resin (hereinafter sometimes abbreviated as MAR). The MAR film can be obtained, for example, by molding a molding material containing a resin component containing MAR as a main component by extrusion molding.

The glass transition temperature (Tg) of the MAR is preferably 115 ° C. or higher, more preferably 120 ° C. or higher, still more preferably 125 ° C. or higher, and particularly preferably 130 ° C. or higher. The MAR film can be excellent in durability by containing MAR having a glass transition temperature (Tg) of 115 ° C. or higher as a main component. The upper limit of the glass transition temperature (Tg) of the MAR is not particularly limited, but is preferably 170 ° C. or lower from the viewpoint of moldability and the like.

As the MAR, any appropriate MAR conventionally used can be adopted. For example, poly (meth) acrylate such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer Polymer, methyl methacrylate- (meth) acrylic acid ester copolymer, methyl methacrylate-acrylic acid ester- (meth) acrylic acid copolymer, (meth) methyl acrylate-styrene copolymer (MS resin, etc.), And polymers having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer resistance, methyl methacrylate-norbornyl (meth) acrylate copolymer). Among these, poly (meth) acrylate C _1-6 alkyl such as poly (meth) acrylate is preferable, and methyl methacrylate is the main component (50 to 100% by weight, preferably 70 to 100% by weight). A methyl methacrylate resin is more preferable.

Specific examples of the MAR include, for example, Acrypet VH and Acrypet VRL20A manufactured by Mitsubishi Rayon Co., and high Tg MAR obtained by intramolecular crosslinking and intramolecular cyclization reaction.

Further, since the MAR is excellent in terms of heat resistance, transparency, and mechanical strength, it may be a MAR having a ring structure in the main chain. As the MAR having a ring structure in the main chain, a MAR having a glutaric anhydride structure or a glutarimide structure (WO2007 / 26659, WO2005 / 108438), a MAR having a maleic anhydride structure or an N-substituted maleimide structure ( JP-A-57-153008 and JP-A-2007-31537), MARs having a lactone ring structure (JP-A-2006-96960, JP-A-2006-171464, JP-A-2007-63541, No. 2008-191426).

The MAR content in the MAR film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. When the MAR content in the MAR film is less than 50% by weight, the high heat resistance and high transparency inherent in MAR may not be sufficiently reflected.

The MAR film may contain other thermoplastic resins in addition to the MAR. Other thermoplastic resins include, for example, olefin polymers such as polyethylene, polypropylene, ethylene-propylene copolymer, poly (4-methyl-1-pentene); vinyl chloride, vinylidene chloride, chlorinated vinyl resins, etc. Vinyl halide polymers; acrylic polymers such as polymethyl methacrylate; styrene polymers such as polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene block copolymer Polyesters such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate; polyamides such as nylon 6, nylon 66 and nylon 610; polyacetals; polycarbonates; polyphenylene oxides; ; Polyether ether ketone; polysulfones; polyethersulfones; polyoxyethylene benzylidene alkylene; polyamideimide; polybutadiene rubber, rubber-like polymer such as ABS resin or ASA resin containing an acrylic rubber.

The content ratio of the other thermoplastic resin in the MAR film is preferably 0 to 50% by weight, more preferably 0 to 40% by weight, still more preferably 0 to 30% by weight, and particularly preferably 0 to 20% by weight.

MAR film may contain an additive. Examples of additives include hindered phenol-based, phosphorus-based and sulfur-based antioxidants; light-resistant stabilizers, weather-resistant stabilizers, heat stabilizers and other stabilizers; reinforcing materials such as glass fibers and carbon fibers; phenyls UV absorbers such as salicylate, (2,2′-hydroxy-5-methylphenyl) benzotriazole, 2-hydroxybenzophenone; near infrared absorbers; tris (dibromopropyl) phosphate, triallyl phosphate, antimony oxide, etc. Flame retardants; Antistatic agents such as anionic, cationic and nonionic surfactants; Colorants such as inorganic pigments, organic pigments and dyes; Organic fillers and inorganic fillers; Resin modifiers; Organic fillers and inorganic fillers Plasticizer; Lubricant; Antistatic agent; Flame retardant; Retardation reducing agent and the like.

The content of the additive in the MAR 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 method for producing the MAR film is not particularly limited. For example, MAR and other polymers and additives are sufficiently mixed by any appropriate mixing method, and the thermoplastic resin composition is previously prepared. Then, this can be formed into a film. Alternatively, the MAR and other polymers, additives, and the like may be made into separate solutions and mixed to form a uniform mixed solution, and then formed into a film.

In order to produce the thermoplastic resin composition, for example, the film raw material is pre-blended with any suitable mixer such as an omni mixer, and then the obtained mixture is extruded and kneaded. In this case, the kneader used for extrusion kneading is not particularly limited. For example, any suitable mixer such as an extruder such as a single screw extruder or a twin screw extruder or a pressure kneader may be used. Can do.

Examples of the film forming method include any appropriate film forming methods such as a solution casting method (solution casting method), a melt extrusion method, a calendar method, and a compression molding method. Among these film forming methods, the solution casting method (solution casting method) and the melt extrusion method are preferable.

Examples of the apparatus for performing the solution casting method (solution casting method) include a drum casting machine, a band casting machine, and a spin coater.

Examples of the melt extrusion method include a T-die method and an inflation method. The molding temperature is preferably 150 to 350 ° C., more preferably 200 to 300 ° C.

When forming a film by the T-die method, a roll is formed by attaching a T-die to the tip of a known single-screw extruder or twin-screw extruder, forming a film with the T-die, and then winding the film. Film can be obtained.

The MAR film may be either an unstretched film or a stretched film. In the case of a stretched film, either a uniaxially stretched film or a biaxially stretched film may be used. In the case of a biaxially stretched film, either a simultaneous biaxially stretched film or a sequential biaxially stretched film may be used. In the case of biaxial stretching, the mechanical strength is improved and the film performance is improved.

The stretching temperature is preferably in the vicinity of the glass transition temperature of the thermoplastic resin composition as the film raw material, and specifically, preferably (glass transition temperature−30 ° C.) to (glass transition temperature + 100 ° C.), more preferably Is in the range of (glass transition temperature−20 ° C.) to (glass transition temperature + 80 ° C.). If the stretching temperature is less than (glass transition temperature-30 ° C.), a sufficient stretching ratio may not be obtained. On the other hand, if the stretching temperature exceeds (glass transition temperature + 100 ° C.), the resin composition 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. There exists a possibility that it may not lead to the improvement of the toughness accompanying extending | stretching that a draw ratio is less than 1.1 times. When the draw ratio exceeds 25 times, there is a possibility that the effect of only increasing the draw ratio (improvement of toughness) is not recognized.

The stretching speed is unidirectional, preferably 10 to 20,000% / min, more preferably 100 to 10,000% / min. When the stretching speed is less than 10% / min, it takes time to obtain a sufficient stretching ratio, and the production cost may increase. If the stretching speed exceeds 20,000% / min, the stretched film may be broken.

The MAR film can be subjected to a heat treatment (annealing) or the like after the stretching treatment in order to stabilize its optical isotropy and mechanical properties. Arbitrary appropriate conditions can be employ | adopted for the conditions of heat processing.

The thickness of the MAR film is preferably 5 to 200 μm, more preferably 10 to 100 μm. If the thickness is less than 5 μm, sufficient strength as an optical film may not be obtained. When the thickness exceeds 200 μm, the transparency is lowered and there is a possibility that it is not suitable for use as an optical film.

The surface tension of the MAR film is preferably 40 mN / m or more, more preferably 50 mN / m or more, and further preferably 55 mN / m or more. By setting the surface wetting tension to at least 40 mN / m or more, the adhesive strength between the MAR film and the easy adhesion layer is further improved. Any suitable surface treatment can be applied to adjust the surface wetting tension. Examples of the surface treatment include corona discharge treatment, plasma treatment, ozone spraying, ultraviolet irradiation, flame treatment, and chemical treatment. Of these, corona discharge treatment and plasma treatment are preferable.

[Easily adhesive layer]
The easy-adhesion layer includes a urethane resin obtained by reacting a polyol and polyisocyanate and (meth) acrylonitrile-based fine particles. The fine particles are excellent in transparency, do not cause haze, and are not colored. For example, when used as a polarizer protective film, the fine particles have an advantage that the optical properties of the polarizer are small.

Generally, the strength and easy adhesion of the easy-adhesion layer are reduced by adding fine particles. However, the easy-adhesion layer of this invention can improve the intensity | strength and easy-adhesiveness of an easy-adhesion layer by including a urethane resin and (meth) acrylonitrile type microparticles | fine-particles. The reason for this is not clear, but the present inventors have inferred that there is an electrostatic charge between the nitrile group, which is an electron-withdrawing functional group of (meth) acrylonitrile, and the carbonyl group or carboxyl group in the urethane resin. The strength of the easy-adhesion layer is improved by the action of a strong force, and further, an electrostatic force works between the nitrile group and the layer adjacent to the easy-adhesion layer, thereby improving the easy adhesion property. Think.

The urethane resin can be obtained by reacting polyol and polyisocyanate. The polyol is not particularly limited as long as it has two or more hydroxyl groups in the molecule, and any appropriate polyol can be adopted. For example, polyacryl polyol, polyester polyol, polyether polyol, polycarbonate polyol and the like can be mentioned. These can be used alone or in combination of two or more.

The urethane resin is preferably obtained by reacting one or two or more polyols selected from polyacryl polyol, polyester polyol and polycarbonate polyol with polyisocyanate. The urethane resin obtained by reacting the above polyol and polyisocyanate has a large polarity and has many carbonyl groups in the molecule, so that it can more effectively improve the strength and easy adhesion of the easy adhesion layer. it can. Of these, urethane resins obtained by reacting polyester polyols with polyisocyanates are preferred because of their particularly high polarity.

The urethane resin preferably has an anionic functional group in the molecule. Examples of the anionic functional group include a carboxyl group, a sulfonic acid group, a phosphoric acid group, and a phenolic hydroxyl group. The urethane resin having an anionic functional group can be obtained, for example, by reacting a diol having an anionic functional group as a chain extender in addition to the polyol and the isocyanate.

The urethane resin particularly preferably has a carboxyl group as an anionic functional group in the molecule. By having a carboxyl group, it is possible to provide an optical film that is excellent in adhesion to other functional films (particularly under high temperature and high humidity). 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 the polyol and the polyisocyanate. Examples of the chain extender having a free carboxyl group include dihydroxycarboxylic acid and dihydroxysuccinic acid. Examples of the dihydroxycarboxylic acid include dialkylolalkanoic acids such as dimethylolalkanoic acid (for example, dimethylolacetic acid, dimethylolbutanoic acid, dimethylolpropionic acid, dimethylolbutyric acid, dimethylolpentanoic acid). These can be used alone or in combination of two or more.

The number average molecular weight of the urethane resin is preferably 5,000 to 600,000, more preferably 10,000 to 400,000. The acid value of the urethane resin is preferably 10 or more, more preferably 10 to 50, and particularly preferably 20 to 45. When the acid value is within such a range, the adhesiveness with other functional films is excellent.

Any appropriate method can be adopted as a method for producing the urethane resin. Specific examples include a one-shot method in which the above components are reacted at once and a multi-stage method in which the components are reacted in stages. When the urethane resin has a carboxyl group, it is preferable to use a multistage method. By using a multistage method, a carboxyl group can be easily introduced. In the production of the urethane resin, any suitable urethane reaction catalyst can be used.

The (meth) acrylonitrile-based fine particles are obtained by polymerizing monomer (meth) acrylonitrile or copolymerizing (meth) acrylonitrile and another monomer. As the other monomer, any appropriate monomer can be adopted as long as copolymerization is possible. Specifically, unsaturated monocarboxylic acids such as (meth) acrylic acid esters and (meth) acrylic acids; unsaturated dicarboxylic acids such as maleic acid and anhydrides and mono- or diesters thereof; (meth) acrylamide, N- Unsaturated amides such as 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; Halogenation such as vinyl chloride and vinylidene chloride α, β-unsaturated aliphatic monomers; α, β-unsaturated aromatic monomers such as styrene and α-methylstyrene; These can be used alone or in combination of two or more. When the (meth) acrylonitrile-based fine particles are a copolymer of (meth) acrylonitrile and another monomer, it is preferable that (meth) acrylonitrile is a main component.

The average particle size of the fine particles is preferably 50 to 350 nm, more preferably 75 to 300 nm, and still more preferably 100 to 250 nm. By using fine particles having such a particle size, irregularities are appropriately formed on the surface of the easy-adhesion layer, and the frictional force at the contact surface between the MAR film and the easy-adhesion layer and / or the easy-adhesion layer is effectively reduced. And blocking can be suppressed.

The method for forming the easy-adhesion layer on the surface of the MAR film is not particularly limited, and a known method can be used. For example, the easy-adhesion layer is formed by applying an easy-adhesive composition containing urethane resin and (meth) acrylonitrile-based fine particles to the surface of an acrylic resin film to form a coating film of the composition, and then forming the formed coating film. It is preferable to form by drying.

The easy-adhesion composition is preferably a water-based composition, and the water-based composition has a smaller work load on the environment when forming the easy-adhesion layer than an organic solvent, and is excellent in workability. . The aqueous composition is, for example, a urethane resin dispersion. The dispersion of urethane resin is typically an emulsion of urethane resin. The urethane resin emulsion becomes a resin layer by drying. The fine particles contained in the emulsion remain in the resin layer as they are.

When the easy-adhesion composition is water-based, a neutralizing agent is preferably used in the production of the urethane resin. By using a neutralizing agent, the stability of the urethane resin in water can be improved. Examples of the neutralizing agent include ammonia, N-methylmorpholine, triethylamine, dimethylethanolamine, methyldiethanolamine, triethanolamine, morpholine, tripropylamine, ethanolamine, triisopropanolamine, 2-amino-2-methyl-1 -Propanol and the like. These can be used alone or in combination of two or more.

When the easy-adhesion composition is water-based, an organic solvent which is preferably inert to the polyisocyanate and compatible with water can be used in the production of the urethane resin. Examples of the organic solvent 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. A solvent etc. are mentioned. These can be used alone or in combination of two or more.

When the easy-adhesion composition is aqueous, the fine particles are preferably blended as an aqueous dispersion. An aqueous easy-adhesion composition containing an aqueous dispersion of fine particles can be more excellent in workability when forming an easy-adhesion layer.

The above easy-adhesive composition preferably contains a crosslinking agent. Arbitrary appropriate crosslinking agents can be employ | adopted for the said crosslinking agent. Specifically, when the urethane resin has a carboxyl group, the crosslinking agent preferably includes a polymer having a group capable of reacting with the carboxyl group. Examples of the group that can react with a carboxyl group include an organic amino group, an oxazoline group, an epoxy group, and a carbodiimide group. Preferably, the crosslinking agent has an oxazoline group. Among these, the crosslinking agent having an oxazoline group has a long pot life at room temperature when mixed with the urethane resin, and the crosslinking reaction proceeds by heating, so that workability is improved.

The above easy-adhesion composition may further contain any appropriate additive. Examples of the additive include a dispersion stabilizer, a thixotropic agent, an antioxidant, an ultraviolet absorber, an antifoaming agent, a thickener, a dispersant, a surfactant, a catalyst, a filler, a lubricant, and an antistatic agent. It is done.

As described above, the easy-adhesion composition is preferably aqueous. The concentration of the urethane resin in the easy-adhesion composition is preferably 1.5 to 15% by weight, more preferably 2 to 10% by weight. If the density | concentration of the urethane resin in an easily bonding composition is the said range, it is preferable from being excellent in the workability | operativity at the time of easily bonding layer formation. When the easy-adhesion composition contains a crosslinking agent, the content of the crosslinking agent (solid content) in the easy-adhesion composition is preferably 1 to 30 parts by weight with respect to 100 parts by weight of the urethane resin (solid content). More preferably, it is 3 to 20 parts by weight. By setting it as 1 weight part or more, it is excellent in adhesiveness with a polarizer, and it can suppress that a phase difference expresses in an easily bonding layer by setting it as 30 weight part or less. The content of the fine particles (solid content) in the easy-adhesion composition is preferably 0.1 to 100 parts by weight with respect to 100 parts by weight of the urethane resin (solid content: solid content including the crosslinking agent if a crosslinking agent is included). The amount is 15 parts by weight, more preferably 0.3 to 5 parts by weight, still more preferably 0.5 to 3 parts by weight. Specifically, the content of the fine particles in the easy-adhesion layer is preferably 0.1 to 15 parts by weight, more preferably 0.3 to 5 parts by weight, and still more preferably 0 to 100 parts by weight of the resin solid content. .5-3 parts by weight. By setting in such a range, the unevenness is appropriately formed on the surface of the easy-adhesion layer, the frictional force on the contact surface between the MAR film and the easy-adhesion layer and / or the easy-adhesion layer is effectively reduced, and blocking is achieved. While being excellent in suppression ability, the intensity | strength and easy adhesiveness of an easily bonding layer improve, and adhesive force with another functional film can fully be ensured. Moreover, when it uses as a polarizer protective film, the influence which it has on the optical characteristic of a polarizing plate can be suppressed more.

The thickness of the easy-adhesion layer can be set to any appropriate value. The thickness is preferably 0.1 to 10 μm, more preferably 0.1 to 5 μm, and particularly preferably 0.2 to 1.0 μm. By setting to such a range, it is excellent in adhesiveness with another functional film, and it can suppress that a phase difference expresses in an easily bonding layer.

The ratio r / d between the thickness d of the easy adhesion layer and the average 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, 0.5 to 1.0 is more preferable. By setting to such a range, blocking resistance in the optical film of the present invention can be ensured. When the 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, blocking resistance. Although it does not contribute to the improvement of the property, there is a risk of increasing the haze ratio of the optical film. When the average 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 lowered and the fine particles are easily removed from the easy-adhesive layer. There is a fear.

[Optical film]
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 a MAR film 2. Specific configurations of the MAR 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 MAR film.

The haze ratio of the optical film of the present invention is preferably 1.0% or less. Note that the haze ratio is measured based on the provisions of JISK7105.

The static friction coefficient on the surface of the easily adhesive layer of the optical film of the present invention is preferably 0.1 to 0.60, more preferably 0.1 to 0.55, and more preferably 0.1 to 0.50. More preferably. If a static friction coefficient is the said range, it can be excellent in the blocking capability which arises at the time of winding of a film.

Since the optical film of the present invention is excellent in blocking resistance when wound on a roll, it may be wound on a roll (may be a film roll). Since the film roll of the optical film of the present invention is excellent in blocking resistance, the film can be excellent in handling properties at the time of winding up the optical film and at the time of unwinding the post-processing.

Various functional coating layers may be formed on the surface of the optical film of the present invention opposite to the surface on which the easy adhesion layer 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. Layer, heat ray shielding layer, electromagnetic wave shielding layer, gas barrier layer and the like.

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 reflection film, an antireflection film, an antiglare film, a brightness enhancement film, and a conductive film for a touch panel. Moreover, among these, it is particularly preferable to use it as a polarizer protective film. 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 an optically anisotropic film (for example, exhibiting birefringence such as retardation).

[Polarizer]
FIG. 2 shows an example of the polarizing plate of the present invention. The polarizing plate 10 shown in FIG. 2 has a structure in which a polarizer 6 is laminated on the surface of the polarizer protective film 4 having the easy adhesion layer 3 on one surface of the MAR film 2 via the adhesive 5. Have Although not shown, the polarizing plate 10 may have a second polarizer protective film laminated on the opposite side of the polarizer 6 from the polarizer protective film 4 via an adhesive layer.

The polarizing plate has a structure in which a polarizer is laminated on an easy-adhesive layer surface of a polarizer protective film having an easy-adhesive layer on the surface of the MAR film via an adhesive layer. Since the easy-adhesion layer formed on the polarizer protective film is excellent in the strength and easy adhesion of the easy-adhesion layer, it can be a polarizing plate excellent in adhesion and durability between the polarizer and the polarizer protective film. . Moreover, since the average particle diameter of the organic fine particles contained in the easy-adhesion layer of the polarizer protective film is smaller than the visible light wavelength, light scattering by the particles can be suppressed, and a polarizing plate having excellent optical properties can be obtained.

As the polarizer, any appropriate polarizer can be adopted depending on the purpose. For example, dichroic substances such as iodine and dichroic dyes are adsorbed on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene-vinyl acetate copolymer partially saponified films. And polyene-based oriented films such as a uniaxially stretched product, a polyvinyl alcohol dehydrated product and a polyvinyl chloride dehydrochlorinated product. Among these, a polarizer obtained by adsorbing a dichroic substance such as iodine on a polyvinyl alcohol film and uniaxially stretching is particularly preferable because of its high polarization dichroic ratio. The thickness of these polarizers is not particularly limited, but is generally about 1 to 80 μm.

Any appropriate adhesive can be adopted as the adhesive forming the adhesive layer. Preferably, the adhesive layer is formed from an adhesive composition containing a polyvinyl alcohol-based resin.

Any appropriate protective film can be adopted as the second polarizer protective film. Typical examples of the material forming the second polarizer protective film include cellulose polymers such as diacetyl cellulose and triacetyl cellulose. The second polarizer protective film may be formed of the same material as the above-described MAR film.

[Image display device]
The image display device of the present invention includes the polarizing plate of the present invention. Specific examples of the image display device can be used for a self-luminous display device such as an electroluminescence (EL) display, a plasma display (PD), and a field emission display (FED), and a liquid crystal display (LCD). A liquid crystal display (LCD) has a liquid crystal cell and the polarizing plate disposed on at least one side of the liquid crystal cell.

[Method for producing optical film]
The method for producing the optical film of the present invention is not particularly limited and can be produced by a known method. For example, a urethane resin and a (meth) acrylonitrile-based material are formed on at least one surface of the MAR film. An easy-adhesion composition containing fine particles is applied to form a coating film of the easy-adhesion composition (application process), and the formed coating film is dried to form an easy-adhesion layer containing the fine particles on the surface ( It is preferable to perform a drying step).

Any appropriate method can be adopted as a method of applying the easy-adhesion composition in the application step. Examples thereof 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 process can be appropriately adjusted according to the thickness required when the coating film becomes an easy-adhesion layer.

The surface to which the easy-adhesion composition in the (meth) acrylic resin film is applied is preferably subjected to a surface treatment. The surface treatment is preferably corona discharge treatment or plasma treatment. By performing the corona discharge treatment, the adhesion between the MAR film and the easy adhesion layer can be improved. The corona discharge treatment can be performed under any appropriate conditions. The amount of corona discharge electron irradiation is, for example, preferably 10 to 150 W / m ² / min, and more preferably 10 to 100 W / m ² / min.

The drying process is not particularly limited, and a conventionally known method can be used. The drying temperature is typically 50 ° C. or higher, preferably 90 ° C. or higher, more preferably 110 ° C. or higher. By setting the drying temperature in such a range, an optical film excellent in color resistance (particularly under high temperature and high humidity) can be obtained. The upper limit of the drying temperature is preferably 200 ° C. or lower, more preferably 180 ° C. or lower.

When producing an optical film that is a stretched film from an unstretched MAR film, and when producing an optical film that is a biaxially stretched film from a uniaxially stretched MAR film by the method for producing an optical film of the present invention, these The MAR film needs to be stretched at some point. The MAR film may be stretched before the easy-adhesion layer is formed or after the easy-adhesion layer is formed. Moreover, you may perform formation of an easily bonding layer and extending | stretching of a MAR film simultaneously.

When forming the easy-adhesion layer and stretching the MAR film at the same time, for example, after the coating process, the MAR film on which the coating film of the easy-adhesion composition is formed may be stretched in a heated atmosphere. Due to the heat applied to the film for stretching, the coating film of the easy-adhesive composition formed on the surface of the MAR film is dried to form an easy-adhesive layer. If it does in this way, since the extending | stretching process of a film and drying of an easily bonding composition can be implemented simultaneously, it is preferable from being excellent in productivity. Usually, the MAR used for the optical film often has a glass transition temperature (Tg) of 100 ° C. or higher, and the above-described stretching temperature forms an easy-adhesion layer from the coating film of the easy-adhesive composition. The temperature is high enough.

The polarizing plate of the present invention is typically produced by laminating the optical film and the polarizer through an adhesive layer. Here, the optical film is laminated so that the easy-adhesion layer is on the polarizer side. Specifically, there is a method of applying the adhesive composition on one side of either a polarizer or an optical film, and then bonding the polarizer and the optical film to dry.

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

Production Example 1
Pellets of methacrylic resin [Tg: 135 ° C] were melt extruded at 280 ° C using a single screw extruder (φ = 20.0mm, L / D = 25) and a coat hanger type T die (width 150mm). The product was cooled using a cooling roll maintained at 110 ° C. to form a methacrylic resin film having a thickness of 100 μm.

Production Example 2
Urethane resin [Daiichi Kogyo Seiyaku, Superflex 210, solid content 35% by weight] 10 g, emulsion containing acrylonitrile-based fine particles (fine particles A) [manufactured by Sekisui Chemical Co., Ltd., ADVANCEL NS K-001, average particle size 150 nm, solid content 20 wt%] 0.22 g and 30 g of pure water were mixed to obtain an easy-adhesion composition (1) as an emulsion dispersion.

Production Example 3
An easy-adhesive composition (2) was obtained in the same manner as in Production Example 2, except that the amount of the emulsion containing the fine particles A was increased to 0.44 g.

Production Example 4
An easy-adhesive composition (3) was obtained in the same manner as in Production Example 2, except that the amount of the emulsion containing the fine particles A was increased to 1.09 g.

Production Example 5
An easy-adhesive composition (4) was obtained in the same manner as in Production Example 2 except that the amount of the emulsion containing the fine particles A was increased to 2.19 g.

Production Example 6
Similar to Production Example 2, except that urethane resin [manufactured by DIC, Hydran AP-40N, solid content 35% by weight] was used instead of urethane resin [Daiichi Kogyo Seiyaku, Superflex 210, solid content 35% by weight]. Thus, an easy-adhesion composition (5) was obtained.

Production Example 7
Instead of the emulsion containing the fine particles A, an emulsion containing acrylonitrile-based fine particles (fine particles B) [Toyobo, Tuftic F-120, average particle size 200 nm, solid content 20 wt%] was used in the same manner as in Production Example 2. Thus, an easy-adhesion composition (6) was obtained.

Production Example 8
Instead of 0.22 g of the emulsion containing fine particles A, 0.88 g of an emulsion containing colloidal silica fine particles (fine particles C) [manufactured by Fuso Chemical Industry, Quartron PL-7, average primary particle size 75 nm, solid content 25 wt%] is used. An easy-adhesive composition (7) was obtained in the same manner as in Production Example 2 except that

Production Example 9
An easy-adhesive composition (8) was obtained in the same manner as in Production Example 8, except that the amount of the emulsion containing the fine particles C was increased to 1.75 g.

Production Example 10
Instead of 0.22 g of the emulsion containing fine particles A, 1.09 g of an emulsion containing colloidal silica fine particles (fine particles D) [manufactured by Fuso Chemical Industries, Quartron PL-20, average primary particle size 220 nm, solid content 20 wt%] is used. An easy-adhesive composition (9) was obtained in the same manner as in Production Example 2 except that

Manufacturability 11
An easy-adhesive composition (10) was obtained in the same manner as in Production Example 10 except that the amount of the emulsion containing the fine particles D was increased to 2.19 g.

Manufacturability 12
An easy-adhesion composition (11), which is an emulsion-like dispersion, was obtained in the same manner as in Production Example 10 except that the emulsion containing the fine particles D was not used.

Example 1
The easy-adhesion composition (1) created in Production Example 2 was applied to one surface of the methacrylic resin film produced in Production Example 1 using a bar coater, and then charged into a hot air dryer at 100 ° C. Dry for 90 seconds. Next, the film is uniaxially stretched using a table stretching machine (stretching ratio: 2.5 times), and the surface of a methacrylic resin film having a thickness of 40 μm has a thickness of 0.3 μm including urethane resin and fine particles. An optical film having an easy adhesion layer was obtained. Content of the microparticles | fine-particles in an easily bonding layer was 1.25 weight part with respect to 100 weight part of urethane resins.

Examples 2 to 6 and Comparative Examples 1 to 5
An optical film was obtained in the same manner as in Example 1 except that the easy-adhesive composition shown in Table 1 was used instead of the easy-adhesive composition (1). Table 1 shows the content (parts by weight) of fine particles with respect to 100 parts by weight of the urethane resin in the easy adhesion layer.

The following evaluation was performed about the optical film obtained by each Example and the comparative example. The evaluation results are shown in Table 1.
(1) Coefficient of static friction (between easy adhesion layer and MAR film)
Measuring device: Tribogear TYPE14 [made by Shinto Kagaku]
The acrylic film fixed in the disk by bringing the optical film obtained in each Example and Comparative Example fixed on a glass plate into close contact with the methacrylic resin film obtained in Production Example 1 fixed in a 10 mmφ stainless steel disk. The static friction coefficient was determined from the maximum load at the start of movement when a load of 200 g was applied from the top of the resin film and moved horizontally at a speed of 6.0 mm / min.
(2) Adhesion A polyvinyl alcohol-based adhesive composition is applied to the easy-adhesion layer side of the optical films obtained in the respective Examples and Comparative Examples, and an iodine-based polarized light having a thickness of 30 μm is interposed through the adhesive composition. After laminating with the polarizer, it was put into a hot air dryer (70 ° C.) and dried for 5 minutes to obtain a laminate bonded with the polarizer. A sample piece having a size of 25 mm × 250 mm was cut out from the laminate obtained above, subjected to adhesion processing on the surface of the optical film, and attached to a glass plate. Thereafter, the polarizer of the laminate was grasped, and the peel adhesion strength at 90 degrees was measured according to the floating roller method of Japan Adhesive Industry Standard JAI 13-1996. The unit of peel adhesion strength was expressed as (N / 25 mm).

As shown in Table 1, the optical films of Examples 1 to 6 having an easy-adhesion layer containing a urethane resin and acrylonitrile-based fine particles are excellent in blocking resistance and compared with the optical film of Comparative Example 5 that does not contain fine particles. The results showed high adhesion to other functional films. On the other hand, the optical films of Comparative Examples 1 to 4 in which an easy-adhesion layer containing urethane resin and colloidal silica fine particles are formed are excellent in blocking resistance, but other functionalities than Comparative Example 5 in which no fine particles are blended. The results showed low adhesion to the film.

Claims

An optical film comprising an easy-adhesion layer containing a urethane resin obtained by reacting polyol and polyisocyanate and (meth) acrylonitrile fine particles on at least one surface of a (meth) acrylic resin film.
2. The optical film according to claim 1, wherein the easy adhesion layer contains 0.1 to 15 parts by weight of the fine particles with respect to 100 parts by weight of the urethane resin.
3. The optical film according to claim 1, wherein the urethane resin has an anionic functional group in the molecule.
3. The optical film according to claim 1, wherein the polyol is at least one selected from polyester polyol, polyacryl polyol, polyether polyol, and polycarbonate polyol.
3. The optical film according to claim 1, wherein the fine particles have a particle size of 50 to 350 nm.
It is a manufacturing method of the optical film of Claim 1 or 2, Comprising: The easily bonding composition containing a urethane resin and (meth) acrylonitrile type microparticles | fine-particles is apply | coated to the at least one surface of a (meth) acrylic-type resin film. A method for producing an optical film, comprising forming a coating film and drying the coating film to form an easy-adhesion layer.