KR102382903B1 - Highly-adhesive composition, optical film using same, and production method therefor - Google Patents

Abstract

While suppressing the fall of the initial stage performance in use for a long time under high temperature, high humidity, it aims at providing the easily bonding composition which can also satisfy the heat-and-moisture resistance in a harsher environment, and the optical film using this. [Solutions] A water-dispersible urethane resin (A) having a glass transition temperature of less than 60°C, and a water-dispersible urethane resin (B) having a glass transition temperature of 60°C or more and 120°C or less and a weight increase rate in a hot water resistance test of 20% or less An easy-to-adhesive composition comprising a. The optical film which formed the easily bonding layer which consists of this easily bonding composition in the at least one surface of a thermoplastic resin film.

Description

A composition for easy adhesion, an optical film using the same, and a manufacturing method thereof {HIGHLY-ADHESIVE COMPOSITION, OPTICAL FILM USING SAME, AND PRODUCTION METHOD THEREFOR}

The present invention relates to an easily bonding composition and an optical film having an easily bonding layer composed of the easily bonding composition. Moreover, this invention relates to the manufacturing method of this optical film, and the polarizing plate and image display apparatus provided with this optical film.

It is known that the acrylic resin film formed of the (meth)acrylic polymer represented by polymethyl methacrylate is excellent in optical properties, such as light transmittance, and is excellent in the balance of mechanical strength and moldability. For this reason, an acrylic resin film is applied to the optical film inserted in image display apparatuses, such as a liquid crystal display device (LCD), a plasma display panel (PDP), and an organic electroluminescent display (OLED).

An optical film is normally used in the state laminated|stacked with other functional films. For example, when used as a polarizer protective film, an optical film is laminated|stacked on the at least one surface of a polarizer via a hydrophilic adhesive bond layer. The obtained polarizing plate is used for an image display apparatus etc. In this case, it is important that the adhesiveness of an optical film and a polarizer is good.

However, an acrylic resin film is inferior in adhesiveness with a hydrophilic adhesive agent, and there exists a problem that adhesiveness with a polarizer is not enough. Therefore, there has been proposed a method of forming an easy-to-adhesive layer mainly comprising a rough-adhesive resin such as polyester, acrylic, or urethane on the surface of the acrylic resin film, and imparting easy adhesion to the acrylic resin film.

On the other hand, portable devices using image display devices, such as LCDs, are used in various environments in recent years regardless of indoors and outdoors, and heat-and-moisture resistance which can withstand a high-temperature, high-humidity environment may be requested|required. The polarizing plate used for such a use is calculated|required by high adhesiveness that delamination does not occur even under high temperature and high humidity.

Therefore, in Japanese Patent Application Laid-Open No. 2009-274390, a laminated film with good adhesion to a polarizer even with a heat history exposed to high temperatures, a part of an acid structure contained in an acid structure-containing aqueous urethane resin on the surface of an acrylic resin film It is described to form an easy-to-adhesive layer containing a water-based urethane resin formed by neutralizing with a nonvolatile base. Japanese Patent Application Laid-Open No. 2009-205135 discloses, as a polarizer protective film excellent in adhesion to a polarizer under high temperature and high humidity, emulsion polymerization of a monomer composition containing polyalkylene glycol (meth) acrylate on the surface of an acrylic resin film, It is described that an easy-to-adhesive layer is formed with an aqueous (meth)acrylic resin dispersion formed therein.

However, the optical film having an easy-to-adhesive layer disclosed in the above document initially exhibits good adhesion, but in the case of long-term use under high temperature and high humidity, a decrease in adhesion to the polarizer is unavoidable, and initial performance (initial adhesion) is reduced for a long time. The problem is that it is not maintained. In addition, the optical film having an easy-to-adhesive layer disclosed in the above document is used for a long time under high temperature (eg, 80°C) or under high temperature and high humidity (eg, 40 to 60°C, 60 to 95%RH). Although the heat-and-moisture resistance was satisfactory, the heat-and-moisture resistance under a harsher environment (eg, 80°C, 90%RH) was not satisfactory.

This invention was made in view of such a problem, While suppressing the fall of the initial stage performance in long-time use under high temperature and high humidity, and also being able to satisfy the heat-and-moisture resistance in a harsher environment, the composition for easy adhesion, and optics using the same It makes it a subject to provide a film.

According to the present invention,

(1) A water-dispersible urethane resin (A) having a glass transition temperature of less than 60°C, and a water-dispersible urethane resin (B) having a glass transition temperature of 60°C or more and 120°C or less and a weight increase rate in a hot water resistance test of 20% or less An easy-to-adhesive composition comprising:

(2) The easily-adhesive composition according to (1) is provided, wherein the weight ratio of the water-dispersible urethane resin (A) to the water-dispersible urethane resin (B) is in the range of 95:5 to 40:60,

(3) The glass transition temperature of the water-dispersible urethane resin (A) is -25 ° C. or higher (1) or (2) is provided, the composition for easy adhesion as described in (2),

(4) The easily-adhesive composition according to any one of (1) to (3), wherein the elongation at break of the water-dispersible urethane resin (A) is 300% or less,

(5) The easily-adhesive composition according to any one of (1) to (4), wherein the elongation at break of the water-dispersible urethane resin (B) is 100% or less,

(6) The easy-to-adhesive composition according to any one of (1) to (5), further comprising 0.1 to 15 parts by weight of fine particles with respect to 100 parts by weight in total of the water-dispersible urethane resins (A) and (B), provided,

(7) An optical film provided with a thermoplastic resin film and an easily bonding layer formed on at least one surface of the thermoplastic resin film, wherein the easily bonding layer is the composition for easy bonding according to any one of (1) to (6). An optical film is provided, characterized in that it is formed with

(8) The optical film according to (7), wherein the resin film is made of a (meth)acrylic resin,

(9) The optical film according to (7) or (8), the adhesive layer, and the polarizer are provided such that the easily bonding layer is in contact with the adhesive layer, and a polarizing plate configured by laminating in this order is provided,

(10) Water-dispersible urethane resin (A) having a glass transition temperature of less than 60°C, diluted with an aqueous solvent, and a glass transition temperature of 60°C or more and 120°C or less, and a weight increase rate in a hot water resistance test of 20% or less A method for manufacturing an optical film comprising a step of applying an easily bonding composition containing a urethane resin (B) to at least one surface of a thermoplastic resin film to form a coating film, and a step of drying the coating film to form an easily bonding layer this is provided

The easily bonding composition of this invention which has said structure is excellent in heat-and-moisture resistance in a harsher environment while suppressing the fall of the initial stage performance in high temperature, high humidity. In addition, in this specification, the term of "(meth)acryl" is used as methacryl, acryl, or both these generic names. The term "(meth)acrylonitrile" is also the same.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows typically an example of the optical film of this invention.
It is sectional drawing which shows typically an example of the polarizing plate of this invention.

[Composition for easy adhesion]

The composition for easy adhesion of the present invention has a glass transition point (hereinafter referred to as Tg) of a water-dispersible urethane resin (A) of less than 60°C, and a Tg of 60°C or more and 120°C or less, and the weight increase rate in the hot water resistance test is 20 % or less of the water-dispersible urethane resin (B) is contained. The easily bonding composition of this invention is excellent in the adhesiveness in long-time use under high temperature, high humidity by mix|blending the urethane resin which satisfy|fills such a characteristic.

Tg of a water-dispersible urethane resin (A) is less than 60 degreeC. It is preferable that Tg is -25 degreeC or more and less than 60 degreeC, More preferably, it is -15 degreeC or more and less than 50 degreeC, More preferably, it is -15 degreeC or more and less than 45 degreeC. When Tg of a water-dispersible urethane resin (A) is the said range, it is excellent in initial stage adhesiveness with a thermoplastic resin film.

In this specification, Tg means the temperature at which the loss elastic modulus (E') shows the maximum in dynamic viscoelasticity measurement. In more detail, using a dynamic viscoelasticity measuring apparatus (Rheogel-E4000 manufactured by UBM Co., Ltd.), the temperature dependence of the loss elastic modulus E˝ was measured under the conditions of a frequency of 10 Hz and a temperature increase rate of 3°C/min, and the obtained E˝ curve Let this maximum temperature be a glass transition temperature (degreeC).

The water-dispersible urethane resin (A) preferably has an elongation at break of 300% or less. As for elongation at break, it is more preferable that it is 100 % or less, and it is still more preferable that it is 50 % or less. When the breaking elongation of a water-dispersible urethane resin (A) is the said range, it is excellent in adhesiveness with a thermoplastic resin film.

About breaking elongation, it measures with the following method. First, an aqueous dispersion of a water-dispersible urethane resin is prepared to have a solid content of 35% by weight, divided into a container such as a petri dish so that the film thickness of the urethane resin after drying is about 500 µm, dried at room temperature for 15 hours, and then dried at 80°C for 6 Time, it is made to dry at 120 degreeC for 20 minutes again, and a urethane resin film is produced. Next, the urethane resin film is cut to a size of 15 mm x 200 mm to cut the sample, and then a sample in which the target point is described at an interval of 50 mm in the center is prepared. Then, the sample is mounted on a tensile tester, the distance between the clamps of the tester is set to 100 mm, and the sample is measured until fracture at a rate of 200 mm/min, and is calculated by the following calculation method. The measurement temperature is 23°C.

Elongation at break (%) = ((Distance between target points at break - Distance between target points before test)/(Distance between target points before test)) × 100

As for the water-dispersible urethane resin (B), Tg is 60 degreeC or more and 120 degrees C or less, and the weight increase rate in a hot water resistance test is 20 % or less. It is preferable that Tg of a water-dispersible urethane resin (B) is 65 degreeC or more and 115 degrees C or less, More preferably, they are 70 degreeC or more and 110 degrees C or less, More preferably, they are 75 degrees C or more and 105 degrees C or less. Moreover, it is preferable that the weight increase rate in a hot water resistance test is 15 % or less, More preferably, it is 10 % or less. If Tg and weight increase rate of a water-dispersible urethane resin (B) are the said range, it is excellent in the adhesiveness in long-time use under high temperature, high humidity.

The weight increase rate in the hot water resistance test is measured by the following method. First, an aqueous dispersion of a water-dispersible urethane resin is prepared to have a solid content of 35% by weight, divided into a container such as a petri dish so that the film thickness of the urethane resin after drying is about 500 µm, dried at room temperature for 15 hours, and then dried at 80°C for 6 Time, it is made to dry at 120 degreeC for 20 minutes again, and a urethane resin film is produced. Next, this urethane resin film is cut|disconnected to the size of 20 mm x 40 mm, the sample is cut out, and the weight (W0) of the sample is measured. Then, the said sample is immersed in 40 degreeC warm water for 24 hours, the sample weight (W1) after immersion is measured, and it computes with the following calculation method.

Weight increase rate (%) = ((W1 - W0)/W0) × 100

It is preferable that the breaking elongation of a water-dispersible urethane resin (B) is 100 % or less. As for elongation at break, it is more preferable that it is 50 % or less, and it is still more preferable that it is 20 % or less. When the breaking elongation of a water-dispersible urethane resin (B) is the said range, it is excellent in adhesiveness with a thermoplastic resin film. In addition, it is as above-mentioned about the measuring method of breaking elongation.

The weight ratio (A/B) of the water-dispersible urethane resin (A) and the water-dispersible urethane resin (B) constituting the easily-adhesive layer in order to exhibit the excellent initial adhesion of the easily-adhesive layer and the excellent adhesion in long-term use under high temperature and high humidity ) is preferably 95:5 to 40:60. Since the further excellent adhesiveness is obtained, weight ratio (A/B) becomes like this. More preferably, it is 85:15-50:50, More preferably, it is 80:20-60:40.

The water-dispersible urethane resins (A) and (B) are not particularly limited as long as they are water-dispersible urethane resins having the above-described properties. For example, in an organic solvent that is inert to isocyanate and compatible with water, polyisocyanate and A linear urethane prepolymer obtained by reacting a polyol to form an isocyanate group-terminated prepolymer and then reacting with a chain extender having a free carboxyl group in water in the presence of a neutralizing agent It can be obtained by chain extension with water and at the same time making it aqueous . In addition, water-based here refers to dispersing or emulsifying resin stably in water. Moreover, it is preferable that water-dispersible urethane resins (A) and (B) have a carboxyl group in a molecule|numerator, and by having a carboxyl group, it is excellent in the adhesiveness in long-time use under high temperature, high humidity.

As polyisocyanate, for example, tetramethylene diisocyanate, dodecamethylene diisocyanate, 1,4-butane diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethyl hexamethylene diisocyanate, 2,4,4- Aliphatic diisocyanates, such as trimethylhexamethylene diisocyanate, lysine diisocyanate, 2-methylpentane-1,5-diisocyanate, and 3-methylpentane-1,5-diisocyanate; Isophorone diisocyanate, hydrogenated xylylene di Alicyclic diisocyanate, such as isocyanate, 4,4'- cyclohexylmethane diisocyanate, 1, 4- cyclohexane diisocyanate, methylcyclohexylene diisocyanate, and 1, 3-bis (isocyanate methyl) cyclohexane; Tolylene diisocyanate , 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4' - Aromatic diisocyanate, such as dibenzyl diisocyanate, 1, 5- naphthylene diisocyanate, xylylene diisocyanate, 1, 3- phenylene diisocyanate, and 1, 4- phenylene diisocyanate; Dialkyldiphenylmethane diisocyanate, tetra and aromatic aliphatic diisocyanates such as alkyldiphenylmethane diisocyanate and α,α,α,α-tetramethylxylylene diisocyanate. These can be used individually or in combination of 2 or more type.

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 employed. For example, polyalkylene glycol, polyacryl polyol, polyester polyol, polyether polyol, polyether ester polyol, polycarbonate polyol, etc. are mentioned. These can be used individually or in combination of 2 or more type.

Examples of the chain extender having a free carboxyl group include dihydroxycarboxylic acid and dihydroxysuccinic acid. Examples of the dihydroxycarboxylic acid include dialkylol alkanoic acids such as dimethylolalkanoic acid (eg, dimethylolacetic acid, dimethylolbutanoic acid, dimethylolpropionic acid, dimethylolbutyric acid, and dimethylolpentanoic acid). can These can be used individually or in combination of 2 or more type.

Examples of the neutralizing agent include ammonia, N-methylmorpholine, triethylamine, dimethyl ethanolamine, methyldiethanolamine, triethanolamine, morpholine, tripropylamine, ethanolamine, triisopropanolamine, 2-amino-2 -methyl-1-propanol etc. are mentioned. These can be used individually or in combination of 2 or more type.

In addition, other usable chain extenders include low molecular weight diol compounds such as ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, furandimethanol, diethylene glycol, triethylene glycol, tetraethylene glycol, and these Polyetherdiol compound obtained by addition polymerization of ethylene oxide, propylene oxide, tetrahydrofuran, etc.; obtained from the low molecular weight diol compound and dicarboxylic acids such as (anhydride) succinic acid, adipic acid, (anhydride) phthalic acid, and anhydrides thereof polyesterdiol having a hydroxyl group at the terminal; polyhydric alcohols such as trimethylolethane and trimethylolpropane; amino alcohols such as monoethanolamine, diethanolamine, and triethanolamine; ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine; Diamine compounds, such as phenylenediamine, toluenediamine, xylene diamine, and isophorone diamine; Water, ammonia, hydrazine, dibasic acid hydrazide, etc. are mentioned. These can be used individually or in combination of 2 or more type.

The number average molecular weights of water-dispersible urethane resins (A) and (B) become like this. Preferably it is 5000-600000, More preferably, it is 10000-40000. The acid value of the water-dispersible urethane resin is preferably 10 or more, more preferably 10 to 50, particularly preferably 20 to 45.

The composition for easy adhesion may be diluted with an aqueous solvent in view of the workability at the time of formation of the easy adhesion layer. Examples of the aqueous solvent include water or an organic solvent having a hydrophilicity with water (e.g., alcohol solvents such as methanol, ethanol, isopropyl alcohol, ethylene glycol and propylene glycol; esters such as ethyl acetate, butyl acetate, and γ-butyrolactone) solvents; ketone solvents such as acetone; ether solvents such as tetrahydrofuran and dioxane; aprotic polar solvents such as N-methylpyrrolidone) can be used, but water is particularly preferred.

The content of the water-dispersible urethane resins (A) and (B) in the easily-adhesive composition is not particularly limited, and may be appropriately set in consideration of coating workability and the like, for example, 1 to 25% by weight is preferable, , More preferably, it is 3 to 20 weight%, More preferably, it is 5 to 15 weight%. If the water-dispersible urethane resins (A) and (B) in the composition for easy bonding are the above ranges, it is preferable at the point excellent in workability at the time of formation of an easily bonding layer. Moreover, although what is necessary is just to set suitably the solid content of an easily bonding composition in consideration of application|coating workability etc., 1 to 30 weight% is preferable, More preferably, 2 to 25 weight%, More preferably, it is 3 to 20 weight%. am.

The easily-adhesive composition may contain any suitable fine particles, preferably water-dispersible fine particles according to a desired function. As the fine particles, both inorganic fine particles and organic fine particles can be used. Examples of the inorganic fine particles include inorganic oxides such as silica, titania, alumina and zirconia, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate. there is. As organic microparticles|fine-particles, silicone resin, a fluorine-type resin, (meth)acrylic-type resin, (meth)acrylonitrile-type resin, etc. are mentioned, for example. Among these, silica or (meth)acrylonitrile-type resin is preferable. The fine particles made of silica or (meth)acrylonitrile-based resin have excellent blocking inhibitory ability, and also have excellent transparency, do not generate haze, and do not cause coloration. small. In addition, the strength and adhesiveness of the easily bonding layer is reduced by blending fine particles, but the easily bonding layer containing fine particles made of a (meth)acrylonitrile-based resin can suppress the decrease in strength and adhesion of the easily bonding layer. It is especially preferable from the point of being able to.

Although the average particle diameter of microparticles|fine-particles is not specifically limited, From a viewpoint of maintaining transparency of an easily bonding layer, Preferably it is 1-500 nm, More preferably, it is 50-350 nm, More preferably, it is 100-300 nm. By using fine particles of such a particle size, irregularities are appropriately formed on the surface of the easily bonding layer, and the frictional force in the contact surface between the thermoplastic resin film and the easily bonding layer and/or the easily bonding layer can be effectively reduced, and blocking is suppressed. can do. The above average particle diameter means a median diameter (d50) measured by laser diffraction/scattering particle size distribution measurement.

It is preferable that content of microparticles|fine-particles is 0.1-15 weight part with respect to a total of 100 weight part of water-dispersible urethane resins (A) and (B) in conversion of solid content. More preferably, it is 0.3-5 weight part, More preferably, it is 0.5-3 weight part. In addition, when other components other than a water-dispersible urethane resin (A) and (B) are included, what is necessary is just to mix|blend microparticles|fine-particles with respect to the solid content which also contained other components.

The easy-to-adhere composition may mix|blend a crosslinking agent in order to improve the heat-and-moisture resistance in high temperature, high humidity. As a crosslinking agent, arbitrary suitable crosslinking agents can be employ|adopted, For example, a urea type, an epoxy type, a melamine type, an isocyanate type, an oxazoline type, a silanol type, carbodiimide type, etc. are mentioned. Moreover, in order to accelerate|stimulate a crosslinking reaction, you may use a catalyst etc. suitably as needed.

The composition for easy adhesion may further include any suitable additives. As an additive, a dispersion stabilizer, a thixotropic agent, antioxidant, a ultraviolet absorber, an antifoamer, a thickener, a dispersing agent, surfactant, a catalyst, a lubricant, an antistatic agent, etc. are mentioned, for example.

[optical film]

An example of the optical film of this invention is shown in FIG. The optical film 1 shown in FIG. 1 has the easily bonding layer 3 formed in one surface of the thermoplastic resin film 2 from the easily bonding composition mentioned above. Moreover, as for the optical film of this invention, the easily bonding layer may be formed in both surfaces of a thermoplastic resin film.

Examples of the thermoplastic resin constituting the thermoplastic resin film include cellulose-based resins such as triacetyl cellulose, polyester-based resins, polyethersulfone-based resins, polycarbonate-based resins, polyamide-based resins, polyimide-based resins, and polyolefins. system resin, cyclic polyolefin resin, (meth)acrylic resin, polyarylate resin, polystyrene resin, polyvinyl alcohol resin, etc. are mentioned. These can be used individually or in combination of 2 or more type. Among these, (meth)acrylic resins (hereinafter, sometimes abbreviated as ACR) have inferior adhesive properties with hydrophilic adhesives, so that the effect of the present invention is particularly remarkable when ACR is used.

It is preferable that Tg of ACR is 115 degreeC or more, More preferably, it is 120 degreeC or more, More preferably, it is 125 degreeC or more. The thermoplastic resin film can be made excellent in durability when Tg contains ACR of 115 degreeC or more as a main component. In addition, the upper limit of Tg is not particularly limited, but is preferably 170° C. or less from the viewpoint of moldability and the like.

Examples of ACR include poly(meth)acrylic acid esters such as polymethyl methacrylate, methyl methacrylate-(meth)acrylic acid copolymer, methyl methacrylate-(meth)acrylic acid ester copolymer, and methyl methacrylate. -Acrylic acid ester-(meth)acrylic acid copolymer, (meth)methylacrylate-styrene copolymer (MS resin, etc.), a polymer having an alicyclic hydrocarbon group, (eg, methyl methacrylate-cyclohexyl methacrylate copolymer) , methyl methacrylate- (meth) acrylate norbornyl copolymer etc.) are mentioned. Among the above, poly(meth)acrylic acid C1-6 alkyl such as poly(meth)methyl acrylate is preferable, and methacryl containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight) is preferable. A methyl acid-type resin is more preferable.

As a specific example of ACR, for example, Mitsubishi Rayon Co., Ltd. "Acripet (registered trademark) VH", "Acripet (registered trademark) VRL20A", high Tg obtained by intramolecular crosslinking or intramolecular cyclization reaction ( and meth)acrylic resins.

It is preferable that ACR has a ring structure in a principal chain at the point which has high heat resistance, high transparency, and high mechanical strength. Examples of the ACR having a ring structure in the main chain include a resin having a glutaric anhydride structure or a glutarimide structure (WO2007/26659 publications, WO2005/108438 publications), maleic anhydride structure, or N-substituted maleic anhydride structure. Resin having a mid structure (Japanese Patent Application Laid-Open No. 57-153008, Japanese Patent Application Laid-Open No. 2007-31537), a resin having a lactone ring structure (Japanese Patent Application Laid-Open No. 2006-96960, Japanese Patent Application Laid-Open No. 2006-171464) , Japanese Patent Application Laid-Open No. 2007-63541, and Japanese Patent Application Laid-Open No. 2008-191426) are mentioned.

The thermoplastic resin film may contain an additive. As an additive, For example, antioxidant, such as hindered phenol type, phosphorus type, sulfur type; Stabilizers, such as a light stabilizer, a weathering stabilizer, a heat stabilizer; Reinforcing materials, such as glass fiber and carbon fiber; Ultraviolet absorber; Near-infrared absorber; Flame retardant; No Antistatic agents such as thermal, 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; Plasticizers; Lubricants; Antistatic agents; Flame retardants ; A phase difference reducing agent, etc. are mentioned.

Although it does not specifically limit as a manufacturing method of a thermoplastic resin film, For example, after fully mixing a thermoplastic resin and another polymer, an additive by arbitrary suitable mixing methods, and setting it as a thermoplastic resin composition beforehand, this film can be molded. Or, after making a thermoplastic resin and another polymer, an additive, etc. into different solutions, mixing and setting it as a uniform liquid mixture, you may film-molding.

In order to manufacture a thermoplastic resin composition, after pre-blending the said film raw material with arbitrary suitable mixers, such as an omni mixer, for example, the obtained mixture is extrusion-kneaded. In this case, the kneader used for extrusion kneading is not specifically limited, For example, arbitrary suitable mixers, such as extruders, such as a single screw extruder and a twin screw extruder, and a pressure kneader, can be used.

As a method of film shaping|molding, arbitrary appropriate film shaping|molding methods, such as a solution casting method (solution casting method), a melt extrusion method, a calendering method, a compression molding method, are mentioned, for example. Among these film forming methods, the melt extrusion method is preferable.

As a melt extrusion method, the T-die method, the inflation method, etc. are mentioned, for example. Molding temperature becomes like this. Preferably it is 150-350 degreeC, More preferably, it is 200-300 degreeC.

In the case of film forming by the T-die method, a T-die is attached to the tip of a known single-screw extruder or twin-screw extruder, a film is formed with the T-die, and then the film is wound to obtain a roll-shaped film.

The thermoplastic resin 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 sufficient. In the case of a biaxially stretched film, either a simultaneous biaxially stretched film or a sequentially biaxially stretched film may be sufficient. When it biaxially stretches, mechanical strength improves and film performance improves.

The stretching temperature is preferably in the vicinity of the glass transition temperature of the thermoplastic resin composition as a raw material for the film, specifically, preferably (Tg-30°C) to (Tg+100°C), more preferably (Tg-20°C) ) to (Tg+80°C). When the stretching temperature is less than (Tg-30°C), there is a possibility that a sufficient stretching ratio cannot be obtained. Conversely, when extending|stretching temperature exceeds (Tg+100 degreeC), the flow (flow) of a resin composition occurs and there exists a possibility that stable extending|stretching cannot be performed.

The draw ratio defined by area ratio becomes like this. Preferably it is 1.1 to 25 times, More preferably, it is 1.3 to 10 times. When the draw ratio is less than 1.1 times, there is a fear that it may not lead to the improvement of toughness accompanying drawing. When a draw ratio exceeds 25 times, there exists a possibility that the effect (toughness improvement) of only raising a draw ratio may not be recognized.

The stretching rate is in one direction, preferably 10 to 20,000%/min, more preferably 100 to 10,000%/min. When the draw rate is less than 10%/min, it takes time to obtain a sufficient draw ratio, and there is a fear that the manufacturing cost becomes high. When the stretching rate exceeds 20,000 %/min, there is a fear that the stretched film may break or the like may occur.

The thermoplastic resin film may be subjected to heat treatment (annealing) or the like after the stretching treatment in order to stabilize the optical isotropy and mechanical properties thereof. Any suitable conditions can be employ|adopted for the conditions of heat processing.

The thickness of a thermoplastic resin film becomes like this. Preferably it is 5-200 micrometers, More preferably, it is 10-100 micrometers. When thickness is less than 5 micrometers, there exists a possibility that sufficient intensity|strength as an optical film may not be acquired. When thickness exceeds 200 micrometers, transparency may fall and there exists a possibility that it may become unsuitable for use as an optical film.

The thickness of the easily bonding layer can be set to arbitrary appropriate values. Preferably it is 0.1-10 micrometers, More preferably, it is 0.1-5 micrometers, Especially preferably, it is 0.2-1 micrometer. By setting in such a range, it is excellent in adhesiveness with another functional film, and it can suppress that retardation is expressed in an easily bonding layer.

Various functional layers may be formed in the surface on the opposite side to the surface in which the easily bonding layer in an optical film is formed as needed. The functional layer is, for example, an antistatic layer, an adhesive layer, an adhesive layer, an easy adhesion layer, an anti-glare (non-glare) layer, an antifouling layer such as a photocatalyst layer, an antireflection layer, a hard coat layer, an ultraviolet shielding layer, a heat ray shielding layer, An electromagnetic wave shielding layer, a gas barrier layer, etc. are mentioned.

An optical film can be used as a polarizer protective film, retardation film, a viewing angle compensation film, a light-diffusion film, a reflective film, an antireflection film, an anti-glare film, a brightness improvement film, and the conductive film for touch panels, for example. Moreover, it is especially preferable to use as a polarizer protective film among these.

[Polarizer]

Next, an example of the polarizing plate of this invention is demonstrated. The polarizing plate 10 shown in FIG. 2 has the easily bonding layer 3 formed from the easily bonding composition mentioned above on one surface of the thermoplastic resin film 2 On the surface of the easily bonding layer side of the optical film 1 which has it It has a structure in which the polarizer 6 was laminated|stacked via the adhesive agent 5. In addition, although not shown in figure, the polarizing plate 10 may have the protective film laminated|stacked through the adhesive bond layer on the opposite side to the optical film 1 of the polarizer 6 .

As a polarizer, arbitrary appropriate polarizers can be employ|adopted according to the objective. For example, a dichroic substance such as iodine or a dichroic dye is adsorbed to a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, or an ethylene-vinyl acetate copolymer-based partially saponified film, and uniaxial and polyene-based oriented films such as the stretched product, a dehydration treatment product of polyvinyl alcohol, and a dehydrochloric acid treatment product of polyvinyl chloride. Among these, the polarizer which made polyvinyl alcohol-type film adsorb|suck dichroism substances, such as an iodine, and carried out uniaxial stretching is especially preferable with a high polarization dichroism ratio. Although the thickness in particular of these polarizers is not restrict|limited, Generally, it is about 1-80 micrometers.

Any suitable adhesive agent can be employ|adopted as an adhesive agent which forms an adhesive bond layer. Preferably, the adhesive layer is formed of an adhesive composition containing a polyvinyl alcohol-based resin.

As a protective film provided on the opposite side of the optical film 1 of the polarizer 6, arbitrary appropriate protective films can be employ|adopted, and it may be formed with the same material as the above-mentioned thermoplastic resin.

[Image display device]

The image display apparatus of this invention is equipped with the above-mentioned polarizing plate. Specific examples of the image display device include self-luminous display devices such as an electroluminescence (EL) display, a plasma display (PD), a field emission display (FED: Field Emission Display), and a liquid crystal display device (LCD). .

[Manufacturing method of optical film]

In the preferable manufacturing method of the optical film of this invention, a water-dispersible urethane resin (A) which is diluted with an aqueous solvent and has a glass transition temperature (Tg) of less than 60 degreeC, and a glass transition temperature (Tg) is 60 degreeC or more and 120 degrees C or less In addition, an easily bonding composition containing a water-dispersible urethane resin (B) having a weight increase rate of 20% or less in the hot water resistance test is applied to at least one surface of a thermoplastic resin film to form a coating film (application step), followed by a coating film is dried to form an easy-to-adhesive layer (drying process).

Any suitable method can be employ|adopted as a method of apply|coating an easily bonding composition in an application|coating process. For example, the bar coat method, the roll coat method, the gravure coat method, the rod coat method, the slot orifice coat method, the curtain coat method, the fountain coat method etc. are mentioned. The thickness of the coating film formed in an application|coating process can be suitably adjusted according to the thickness required when the said coating film becomes an easily bonding layer.

It is preferable that the surface to which the easily bonding composition in a thermoplastic resin film is apply|coated is surface-treated. As surface treatment, it is preferable that they are corona discharge treatment and plasma treatment. By performing corona discharge treatment or plasma treatment, the adhesiveness of a thermoplastic resin film and an easily bonding layer can be improved.

A drying process is not restrict|limited in particular, A conventionally well-known method can be used. As a drying temperature, it is 50 degreeC or more typically, Preferably it is 90 degreeC or more, More preferably, it is 110 degreeC or more. By making drying temperature into such a range, it can be set as the optical film excellent in color resistance (in particular, under high temperature, high humidity). The upper limit of the drying temperature is preferably 200°C or less, more preferably 180°C or less.

When extending|stretching a thermoplastic resin film, extending|stretching may be performed before formation of an easily bonding layer, and may be performed after formation of an easily bonding layer. Moreover, you may perform formation of an easily bonding layer, and extending|stretching of a thermoplastic resin film simultaneously.

When forming an easily bonding layer and extending|stretching of a thermoplastic resin film simultaneously, what is necessary is just to extend|stretch the thermoplastic resin film in which the coating film of the easily bonding composition was formed, for example in a heating atmosphere after an application|coating process. The coating film of the easily bonding composition formed on the surface of a thermoplastic resin film is dried by the heat applied to the said film for extending|stretching, and it becomes an easily bonding layer. In this way, it is preferable at the point which the extending|stretching process of a film and drying of an easily bonding composition can be performed simultaneously, and is excellent in productivity.

Example

Hereinafter, the present invention will be described in more detail by way of Examples. In addition, this invention is not limited to a following example.

The following was used as a raw material. In addition, with respect to the characteristic values of the water-dispersible urethane resins (A) and (B), the glass transition temperature, the elongation at break, and the weight increase rate in the hot water resistance test are shown in Table 1.

<Water-dispersible urethane resin (A)>

- Emulsion of water-dispersible urethane resin (A-1) [manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., Superflex (trademark) 210, solid content 35 wt%]

- Emulsion of water-dispersible urethane resin (A-2) [manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., Super Flex (trademark) 150, solid content 30 wt%]

- Emulsion of water-dispersible urethane resin (A-3) [manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., Superflex (registered trademark) 420, solid content: 32 wt%]

- Emulsion of water-dispersible urethane resin (A-4) [manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., Superflex (registered trademark) 460, solid content 38 wt%]

<Water-dispersible urethane resin (B)>

- Emulsion of water-dispersible urethane resin (B-1) [manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., Superflex (registered trademark) 130, solid content 35 wt%]

- Emulsion of water-dispersible urethane resin (B-2) [manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., Superflex (registered trademark) 870, solid content: 30 wt%]

<fine particles>

Emulsion containing acrylonitrile fine particles (PAN fine particles) [manufactured by Sekisui Chemical Industry Co., Ltd., ADVANCELL NS K-001, average particle diameter 150 nm, solid content 20 wt%]

Examples 1 to 4 and Comparative Examples 1 to 8

1. Preparation of composition for easy adhesion

Each component shown in Table 2 selected and mixed the said raw material emulsion so that the solid content (unit is weight part) shown in Table 2 might be contained, and the easy adhesion composition was manufactured. Moreover, ion-exchange water was used as an aqueous solvent, and it prepared so that the solid content of an easily bonding composition might be finally set to 8 weight%.

2. Preparation of optical films

Pellets of methacrylic resin [Tg: 135 ° C., melt viscosity: 700 Pa s (temperature 270 ° C., shear rate 100 (1/sec))] were cut by a single screw extruder (φ = 20.0 mm, L/D = 25) And melt-extruded at 280 ° C. using a coat hanger type T die (width 150 mm), and the resin in the molten state was discharged to a cooling roll maintained at 110 ° C. to form a methacrylic resin film with a thickness of 100 µm. . Next, on one surface of the methacrylic resin film, the easily-adhesive composition obtained above was applied using a bar coater, and then put into a hot air dryer and dried at 100°C for 90 seconds. Then, the film was uniaxially stretched using a table stretching machine (stretch ratio: 2.5 times), and on the surface of a 40 μm thick methacrylic resin film, an optical film having an easily adhesive layer with a thickness of 0.3 μm was produced.

3. Preparation of Polarizer

The polyvinyl alcohol-type adhesive composition was apply|coated to the easily bonding layer side of the optical film obtained above. Moreover, the polyvinyl alcohol-type adhesive composition was apply|coated to the one side of the 40-micrometer-thick triacetyl cellulose film (protective film) which performed the saponification process. Next, an optical film and a protective film are laminated on each side of a polarizer having a thickness of 30 µm via a polyvinyl alcohol-based adhesive coating layer, and the resulting laminate is placed in a hot air dryer (70 ° C.) and dried for 5 minutes, a polarizing plate was manufactured Moreover, the reference polarizing plate for evaluation in which both sides of the polarizer formed the triacetyl cellulose protective film was manufactured similarly.

Evaluation shown below was performed about the polarizing plate obtained above. Table 2 shows the evaluation results.

(1) Initial adhesion

After cutting out the test piece of the dimension of 25 mm x 250 mm from the polarizing plate obtained above, and giving adhesion processing to the surface of the optical film of a test piece, it affixed on the glass plate, and the sample for a measurement was obtained. Thereafter, a cut was placed between the polarizer and the optical film of the sample, the polarizer and the protective film were held, and the peel adhesive strength at 90 degrees was measured according to the floating roller method of Japanese Adhesive Industry Standard JAI 13-1996. In addition, also in the reference polarizing plate, peel adhesive strength was measured on the same conditions. From the measurement result, the following reference|standard evaluated peel adhesive strength.

◎: Excellent peel adhesive strength than a reference polarizing plate

○: Same peel adhesive strength as the reference polarizing plate

(triangle|delta): peel adhesive strength inferior to a reference|standard polarizing plate

× : Measurement is not possible because it is not in close contact.

(2) Heat-and-moisture resistance (60 ℃, 90 %RH)

Peel adhesive strength was measured in the same manner as in evaluation of initial adhesion, except that the measurement sample obtained in the same manner as above was placed in a constant temperature and humidity chamber at a temperature of 60 ° C. and humidity of 90% RH and subjected to heat treatment leaving it to stand for 250 hours and 500 hours. measured. From the measurement result, the following reference|standard evaluated peel adhesive strength.

◎: Excellent peel adhesive strength than a reference polarizing plate

○: Same peel adhesive strength as the reference polarizing plate

(triangle|delta): peel adhesive strength inferior to a reference|standard polarizing plate

× : Measurement is not possible because it is not in close contact.

(3) Heat-and-moisture resistance (80 ℃, 90 %RH)

Peel adhesive strength was measured in the same manner as in evaluation of initial adhesiveness, except that the sample for measurement obtained in the same manner as described above was put into a constant temperature and humidity chamber with a temperature of 80°C and a humidity of 90% RH and subjected to heat treatment of leaving it to stand for 100 hours. From the measurement result, the following reference|standard evaluated peel adhesive strength.

◎: Excellent peel adhesive strength than a reference polarizing plate

○: Same peel adhesive strength as the reference polarizing plate

(triangle|delta): peel adhesive strength inferior to a reference|standard polarizing plate

× : Measurement is not possible because it is not in close contact.

As shown in Table 2, a water-dispersible urethane resin (A) having a Tg of less than 60°C and a water-dispersible urethane resin (B) having a Tg of 60°C or more and 120°C or less and a weight increase rate in the hot water resistance test of 20% or less The optical films of Examples 1-4 using the easily bonding layer to contain were excellent in initial stage adhesiveness, and showed the result excellent also in the adhesiveness in long-time use under high temperature, high humidity. On the other hand, as shown in Table 2, the optical films of Comparative Examples 1 to 6 containing only the water-dispersible urethane resin (A) having a Tg of less than 60° C. showed poor adhesion in long-term use under high temperature and high humidity. Moreover, the optical film of Comparative Examples 7 and 8 containing only the water-dispersible urethane resin (B) whose Tg is 60 degreeC or more and 120 degrees C or less and the weight increase rate in a hot water resistance test is 20% or less, the adhesiveness after a high temperature, high humidity process Although improved, it showed the result inferior to initial stage adhesiveness.

Claims (10)

An optical film comprising a thermoplastic resin film and an easily bonding layer formed on at least one surface of the thermoplastic resin film,
The easy-to-adhesive layer has a glass transition temperature of less than 60°C and a water-dispersible urethane resin (A) having a breaking elongation of 300% or less, and a glass transition temperature of 60°C or more and 120°C or less, and the weight increase rate in the hot water resistance test is An optical film formed of an easily bonding composition containing 20% or less of a water-dispersible urethane resin (B), wherein the weight ratio of the water-dispersible urethane resin (A) to the water-dispersible urethane resin (B) is 85:15-50: An optical film, characterized in that in the range of 50. The method of claim 1,
The optical film whose weight ratio of the said water-dispersible urethane resin (A) and the said water-dispersible urethane resin (B) is the range of 70:30-80:20. The method of claim 1,
The optical film whose glass transition temperature of the said water-dispersible urethane resin (A) is -25 degreeC or more. The method of claim 1,
The optical film whose breaking elongation of the said water-dispersible urethane resin (A) is 100 % or less. The method of claim 1,
The said thermoplastic resin film is an optical film which consists of (meth)acrylic-type resin. The polarizing plate comprised by the optical film in any one of Claims 1-5, an adhesive bond layer, and a polarizer laminated|stacking in this order, making the said easily bonding layer contact this adhesive bond layer. A water-dispersible urethane resin (A) having a glass transition temperature of less than 60°C and an elongation at break of 300% or less, diluted with an aqueous solvent, and a glass transition temperature of 60°C or more and 120°C or less, and weight increase rate in a hot water resistance test A step of forming a coating film by applying an easily bonding composition containing 20% or less water-dispersible urethane resin (B) to at least one surface of a thermoplastic resin film, and drying the coating film to form an easily bonding layer. A method for producing an optical film comprising:
A method for producing an optical film, wherein a polymerization ratio of the water-dispersible urethane resin (A) to the water-dispersible urethane resin (B) is in the range of 85:15 to 50:50. delete delete delete

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