KR101567618B1 - Method for production of acrylic film, and acrylic film produced by the method - Google Patents

Abstract

A method for producing an acrylic film having excellent flexibility and surface property with high productivity and an acrylic film produced by the method are provided below.
A process for producing an acrylic film containing an acrylic resin (A) and an acrylic particle (C) of less than 5% by mass as a solvent, wherein the solvent A satisfies the following relationships (1) and (2) B and a residual solvent in an amount of 5 to 50 mass%, and a step of removing the glass transition temperature of the acrylic film from the glass transition temperature + 10 占 폚 to the glass transition temperature + 40 < 0 > C.
(1) boiling point of solvent A + 35 DEG C <boiling point of solvent B
(2) Mass ratio of solvent A to solvent B in the mixed solution A: B = 98: 2 to 70:30

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an acrylic film and an acrylic film produced by the method,

The present invention relates to a process for producing an acrylic film for optical applications having excellent flexibility and surface properties.

BACKGROUND ART An acrylic film typified by a polymethyl methacrylate film has been expected as an optical film because its transmittance in a visible light region, intrinsic birefringence, and photoelastic coefficient are small.

However, acrylic films are liable to cause cracking and have poor handling properties, which has prevented their use.

As a countermeasure against breakage, a method of stretching an acrylic film has been proposed (JP-A-2001-3258).

Further, there is also known a method in which elastic particles are added to a specific acrylic film and then subjected to a heat treatment to make them flexible (Japanese Patent Application Laid-Open No. H06-32836).

A technique of mixing a flexible resin having a glass transition temperature of 10 占 폚 or less instead of elastic particles has been proposed (Patent Document 3 below)

Since the method of Patent Document 1 is applied to an acrylic film which is likely to be cracked originally, it is difficult to establish the production conditions, and the versatility is insufficient.

In the method of Patent Document 2, there is a problem that the time required for the heat treatment is very long and the surface property of the produced acrylic film is also deteriorated. Further, when the acrylic film is used, for example, in a liquid crystal display device or the like, the film is deformed by continuous use for a long time, and a clear image can not be displayed in some cases.

The method of Patent Document 3 is effective for a specific acrylic resin having a lactone ring structure and is based on melting flexibility. Therefore, the surface property does not exceed that of Patent Document 2. As in Patent Document 2, there was also a problem that the heat resistance remarkably decreased.

Japanese Patent Application Laid-Open No. 2005-162835 International Publication No. 2005/105918 Japanese Patent Application Laid-Open No. 2007-100044

The present invention provides a method for producing an acrylic film having excellent flexibility and surface properties with high productivity and an acrylic film produced by the method.

The above object of the present invention is solved by the following means.

1. A process for producing an acrylic film containing an acrylic resin (A) and an acrylic particle (C) of less than 5 mass% as a solvent, wherein a solvent which satisfies the following relationships (1) and (2) The step of drying the mixed solvent of A and B until the amount of the residual solvent is 5 to 50 mass% and the step of removing the residual solvent by 5 to 50 mass%, wherein the apparent glass transition temperature (hereinafter, Tg) + 10 占 폚 to apparent Tg + 90 占 폚.

(1) boiling point of solvent A + 35 DEG C <boiling point of solvent B

(2) Mass ratio of solvent A to solvent B in the mixed solution A: B = 98: 2 to 70:30

2. The acrylic film produced by the production method according to the above 1, wherein no ductile fracture occurs in an atmosphere at 23 占 폚 and 55% RH, a tensile softening point is 105 to 145 占 폚, and a haze value is less than 1.0%.

3. The acrylic film according to claim 1, wherein the acrylic film is a resin film containing the acrylic resin (A) and the cellulose ester resin (B) in a mass ratio of 95: 5 to 30:70 and in a commercial state, (B) having a weight average molecular weight Mw of 75,000 or more and 280,000 or less, a total substitution degree (T) of an acyl group of 2.0 or more and 3.0 or less, a carbon number of 3 or more and 7 or less, a molecular weight Mw of 80000 or more and 1,000,000 or less, The acrylic film according to 2 above, wherein the substitution degree of the actual group is 1.2 or more and 3.0 or less.

According to the present invention, an acrylic film having excellent flexibility and surface properties can be produced with high productivity.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing a dope manufacturing process, a softening process and a drying process of a solution casting film-forming method;

The present invention relates to a process for producing an acrylic film containing an acrylic resin (A) and an acrylic particle (C) of less than 5 mass% as a solvent by a solution casting film-forming method and satisfying the following relations (1) and A step of using a mixed solvent of the solvents A and B and drying until the residual solvent becomes 5 to 50 mass% and a step of heating the acrylic film at an apparent Tg + 10 deg. C to Tg + 90 &lt; [deg.] &Gt; C.

(1) boiling point of solvent A + 35 DEG C <boiling point of solvent B

(2) Mass ratio of solvent A to solvent B in the mixed solution A: B = 98: 2 to 70:30

In other words, in the present invention, when the acrylic film is subjected to solution casting, the time required for the heat treatment can be shortened by using a mixed solution satisfying the relations (1) and (2) And the surface of the finished acrylic film is also excellent.

The acrylic film of the present invention is formed by dissolving at least an acrylic resin (A) and acrylic particles (C) of less than 5 mass% in a mixed solvent of Solvent A and Solvent B, and plied on a support such as a belt or a drum.

<Mixed solvent of solvent A and solvent B>

The mixed solvent of the solvent A and the solvent B in the present invention is a mixed solvent consisting of at least the solvent A and the solvent B and the total of the solvents A and B is 70% by mass or more of the total mixed solvent.

Solvent A and Solvent B satisfy the following relationship.

(1) boiling point of solvent A + 35 DEG C <boiling point of solvent B

(2) Mass ratio of solvent A to solvent B in the mixed solution A: B = 98: 2 to 70:30

Solvent A has a boiling point of 40 to 95 캜, preferably 50 to 90 캜. The boiling point of the solvent B is more than 75 DEG C but not more than 155 DEG C, preferably 85 DEG C or more and 150 DEG C or less.

As solvent A, methanol (MeOH, 64 DEG C), ethanol (EtOH, 77 DEG C), methyl acetate (MeAc, 55 DEG C), ethyl acetate (EtAc, 75 DEG C), methylene chloride , 55 ° C), methyl ethyl ketone (MEK, 77 ° C), and the like. In (), abbreviations and boiling points are indicated (abbreviation, boiling point).

Butyl alcohol (nBuOH, 118 占 폚), isoamyl alcohol (iAmOH, 126 占 폚), cyclohexanol (CHOH, 152 占 폚) , Ethylene glycol monomethyl ether (EGMME, 124 DEG C), ethylene glycol monoethyl ether (EGMEE, 132 DEG C), and cyclohexanone (CHNO, 150 DEG C).

Two or more solvents A and B may be used.

Solvent A has a solubility of 10% by mass or more with respect to the acrylic resin (A) alone. The mixed solvent may be mixed with a solvent other than the solvents A and B in a range of less than 30 mass% of the mixed solvent.

Process of heat-treating the acrylic film in the range of Tg + 10 占 폚 to Tg + 90 占 폚 in the state where the residual solvent is 5 to 50 mass%

In the present invention, heat treatment is performed in the range of apparent Tg + 10 ° C to Tg + 90 ° C of the acrylic film in a state where the residual solvent is 5 to 50 mass% of the acrylic film. Therefore, in the drying step, the residual solvent is adjusted to be 5 to 50% by mass.

The heat treatment is performed in the range of apparent Tg + 10 ° C to Tg + 90 ° C of the acrylic film. It is preferably from Tg + 50 to Tg + 90 占 폚.

The time for the heat treatment is 15 to 90 seconds, preferably 30 to 60 seconds.

In the present invention, by using a mixed solvent, rapid evaporation of the solvent at the initial stage of drying in the drying step can be prevented, and as a result, the surface shape of the film can be kept good.

Further, since the boiling point of the solvent B is relatively high, the content ratio of the solvent B is higher than the initial solvent ratio in the state where the residual solvent amount is 5 to 50 mass%, and the solvent B has an absolutely high boiling point. It is considered that the Tg of the acrylic film is apparently lowered and the effect of the heat treatment is amplified and the effect of the heat treatment is efficiently expressed in a portion where the residual solvent is as much as 5 to 50 mass% have.

The apparent Tg of the acrylic film in the present invention indicates a state in which a phenomenon such as softening occurs at a temperature lower than an actual glass transition temperature by including a solvent. Specifically, it can be measured by the following procedure.

In a sufficiently dry acrylic film (residual solvent amount of less than 1%) of the present invention, the film was preliminarily heated for 24 hours under an atmosphere of 23 ° C and 55% RH using a differential scanning calorimeter (DSC-7 type, manufactured by Perkin Elmer) One sample is measured in a nitrogen stream at a heating rate of 20 占 폚 / min and a glass transition temperature (Tg) is determined according to JIS K7121 (1987).

Next, the elastic modulus of the film is measured at a temperature of at least 5 points (intervals of 10 占 폚 or more) from 30 占 폚 to 100 占 폚 to prepare an approximate curve (calibration curve). Further, the elasticity of the acrylic film including the residual solvent is measured at 30 占 폚, and the value at this time is referred to as Ea (GPa). A temperature corresponding to Ea (GPa) is calculated from a previously prepared calibration curve, and this value is referred to as Ta (占 폚).

Finally, the apparent Tg

Apparent Tg (占 폚) = Tg-Ta (占 폚) -30 (占 폚)

.

<Configuration of Acrylic Film>

The acrylic film of the present invention is composed of at least an acrylic resin (A) and acrylic particles (C) of less than 5 mass%, and includes other additives.

And, in an atmosphere of 23 占 폚 and 55% RH, soft tensile softening point is 105 to 145 占 폚 and haze value is less than 1.0% without causing soft fracture.

The acrylic film is a resin film containing an acrylic resin (A) and a cellulose ester resin (B) in a mass ratio of 95: 5 to 30:70 in a commercial state, and the weight average molecular weight Mw (B) having a weight average molecular weight Mw of not less than 75000 and not more than 280,000, a total degree of substitution (T) of an acyl group of not less than 2.0 and not more than 3.0, and a carbon number of not less than 3 and not more than 7, Is not less than 1.2 and not more than 3.0.

In the present invention, it is preferable that the acrylic film is in a form containing 0.1 to 5 mass% of acrylic particles (C) based on the total mass of the resin constituting the acrylic film.

&Lt; Acrylic resin (A) >

The acrylic resin (A) used in the present invention also includes methacrylic resin. The resin is preferably composed of 50 to 100 mass% of methyl methacrylate units and 0 to 50 mass% of other monomer units copolymerizable therewith.

Examples of other copolymerizable monomers that can be copolymerized include alkyl methacrylates having 2 to 18 carbon atoms in the alkyl group, alkyl acrylates having 1 to 18 carbon atoms in the alkyl group, alpha, beta -unsaturated acids such as acrylic acid and methacrylic acid, Aromatic vinyl compounds such as unsaturated dicarboxylic acids such as fumaric acid and itaconic acid, styrene,? -Methylstyrene and nuclear substituted styrene,?,? -Unsaturated nitriles such as acrylonitrile and methacrylonitrile, Acid, maleimide, N-substituted maleimide, and glutaric anhydride. These may be used alone or in combination of two or more.

Of these, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, and 2-ethylhexyl acrylate are preferable from the viewpoint of thermal decomposition resistance and fluidity of the copolymer , Methyl acrylate or n-butyl acrylate are particularly preferably used.

The acrylic resin (A) used in the acrylic film of the present invention has a weight average molecular weight (Mw) of from 80000 to 1000000, preferably from 150000 to 400000 in terms of mechanical strength as a film and fluidity in producing a film.

The weight average molecular weight of the acrylic resin (A) of the present invention can be measured by gel permeation chromatography. The measurement conditions are as follows.

Solvent: methylene chloride

Column: Shodex K806, K805, K803G (connected to three parts manufactured by Showa Denko K.K.)

Column temperature: 25 ° C

Sample concentration: 0.1 mass%

Detector: RI Model 504 (manufactured by GL Science)

Pump: L6000 (manufactured by Hitachi Seisakusho Co., Ltd.)

Flow rate: 1.0 ml / min

Calibration curves: Standard polystyrene STK standard A calibration curve with 13 samples of polystyrene (manufactured by TOSOH CORPORATION) Mw = 2,800,000 to 500 was used. 13 samples are preferably used at substantially equal intervals.

The method for producing the acrylic resin (A) in the present invention is not particularly limited, and any known method such as suspension polymerization, emulsion polymerization, bulk polymerization, or solution polymerization may be used. As the polymerization initiator, conventional peroxide-based or azo-based ones can be used, and redox systems can also be used.

The polymerization temperature may be 30 to 100 占 폚 for suspension or emulsion polymerization and 80 to 160 占 폚 for bulk polymerization or solution polymerization. Further, in order to control the reduced viscosity of the produced copolymer, polymerization may be carried out using alkyl mercaptan or the like as a chain transfer agent.

By making this molecular weight, compatibility between heat resistance and brittleness can be achieved.

Commercially available acrylic resin (A) of the present invention can also be used. (Manufactured by Asahi Kasei Chemicals Corporation), Dianal BR52, BR80, BR83, BR85 and BR88 (manufactured by Mitsubishi Rayon Co., Ltd.) and KT75 (manufactured by Denki Kagaku Kogyo Co., Ltd.) And the like.

&Lt; Acrylic particles (C) >

The acrylic particles (C) of the present invention are present in the form of particles in the acrylic film containing the acrylic resin (A).

Here, for example, a predetermined amount of the prepared acrylic film is taken, dissolved in a solvent, and stirred, and the resultant mixture is sufficiently dissolved and dispersed, and a membrane made of PTFE having a pore diameter smaller than the average particle diameter of the acrylic particles (C) Filter, and the weight of the insoluble matter collected by filtration is preferably 90% by mass or more of the acrylic particles (C) added to the acrylic film.

The acrylic particles (C) used in the present invention are preferably acrylic particles (C) having a layer structure of two or more layers, particularly preferably the following multi-layer structure acrylic granular composite.

The multi-layered acrylic granular composite refers to a particulate acrylic polymer having a structure in which the innermost hard layer polymer, the crosslinked soft layer polymer exhibiting rubber elasticity, and the outermost hard layer polymer are laminated in layers from the center toward the outer periphery .

Preferred examples of the multi-layered acrylic particulate composite used in the acrylic resin composition of the present invention include the following. (a) a monomer mixture comprising 80 to 98.9 mass% of methyl methacrylate, 1 to 20 mass% of an alkyl acrylate having an alkyl group of 1 to 8 carbon atoms, and 0.01 to 0.3 mass% of a multi-functional graft, (B) from 75 to 98.5% by weight of an alkyl acrylate having from 4 to 8 carbon atoms in the alkyl group, from 0.01 to 5% by weight of a polyfunctional crosslinking agent and from 0.5 to 5% by weight of a polyfunctional grafting agent in the presence of the innermost hard layer polymer, (C) a polymer comprising 80 to 99% by mass of methyl methacrylate and 1 to 8% by number of alkyl groups having 1 to 8 carbon atoms in the alkyl group in the presence of the polymer comprising the innermost hard layer and the crosslinked soft layer, Acrylate and 1 to 20% by mass of an acrylate, and has a three-layer structure composed of an outermost layer polymer obtained by polymerizing a monomer mixture composed of The obtained three-layer structure polymer is composed of 5 to 40 mass% of the innermost hard layer polymer (a), 30 to 60 mass% of the soft layer polymer (b), and 20 to 50 mass% of the outermost hard layer polymer An acrylic granular complex having an insoluble portion when fractionated and a swelling degree of methyl ethyl ketone in an insoluble portion of 1.5 to 4.0.

Furthermore, as disclosed in Japanese Patent Publication No. 60-17406 or Japanese Patent Publication No. 3-39095, not only the composition and the particle diameter of each layer of the multi-layered acrylic particulate composite are specified, but also the multi- By setting the tensile modulus of elasticity of the composite or the methyl ethyl ketone swelling degree of the acetone insoluble portion within a specific range, it is possible to realize a balance of sufficient impact resistance and stress relaxation whitening resistance.

Here, the innermost hard layer polymer (a) constituting the multi-layer structure acrylic granular composite contains 80 to 98.9% by mass of methyl methacrylate, 1 to 20% by mass of an alkyl acrylate having an alkyl group of 1 to 8 carbon atoms and a multi- By mass to 0.3% by mass of the monomer mixture.

Examples of the alkyl acrylate having 1 to 8 carbon atoms in the alkyl group include methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, And methyl acrylate or n-butyl acrylate is preferably used.

The proportion of the alkyl acrylate units in the innermost hard layer polymer (a) is from 1 to 20% by mass, and when the above units are less than 1% by mass, the thermal decomposition property of the polymer is increased. On the other hand, The glass transition temperature of the innermost hard layer polymer (c) is lowered, and the impact resistance imparting effect of the three-layer structure acrylic granular composite is lowered.

Examples of the multifunctional grafting agent include multifunctional monomers having other polymerizable functional groups such as acrylic acid, methacrylic acid, maleic acid, and allyl esters of fumaric acid, and allyl methacrylate is preferably used. The multifunctional grafting agent is used for chemically bonding the innermost hard layer polymer and the soft layer polymer, and the ratio used for polymerization in the innermost hard layer is 0.01 to 0.3 mass%.

The crosslinked soft polymer layer (b) constituting the acrylic granular composite is produced by polymerizing, in the presence of the innermost hard layer polymer (a), from 75 to 98.5% by mass of alkyl acrylate having 1 to 8 carbon atoms in the alkyl group, 0.01 to 5% % And a polyfunctional grafting agent in an amount of 0.5 to 5% by mass.

As the alkyl acrylate having 4 to 8 carbon atoms in the alkyl group, n-butyl acrylate and 2-ethylhexyl acrylate are preferably used.

It is also possible to copolymerize other monofunctional monomers copolymerizable with these polymerizable monomers at 25 mass% or less.

Examples of other monofunctional monomers capable of copolymerization include styrene and substituted styrene derivatives. The ratio of the alkyl acrylate having a carbon number of 4 to 8 in the alkyl group to the styrene is such that the larger the number of electrons, the lower the glass transition temperature of the produced polymer (b), that is, the softened.

On the other hand, from the viewpoint of transparency of the resin composition, it is preferable that the refractive index of the soft layer polymer (b) at room temperature is higher than the refractive index of the innermost hard layer polymer (a), the outermost hard layer polymer (c), and the hard thermoplastic acrylic resin And the ratio of the two is selected in consideration of these.

For example, in applications where the coating layer thickness is small, styrene may not necessarily be copolymerized.

As the multifunctional grafting agent, those exemplified in the paragraph of the innermost hard layer polymer (a) can be used. Here, the polyfunctional grafting agent to be used is used for chemically bonding the soft layer polymer (b) and the outermost hard layer polymer (c), and the ratio used in the polymerization of the innermost hard layer is 0.5 By mass to 5% by mass.

As the polyfunctional crosslinking agent, generally known crosslinking agents such as a divinyl compound, a diallyl compound, a diacryl compound and a dimethacryl compound can be used, but polyethylene glycol diacrylate (molecular weight: 200 to 600) is preferably used.

The multifunctional crosslinking agent used here is used for producing a crosslinked structure at the time of polymerization of the soft layer (b) and exhibiting the effect of imparting impact resistance. However, when the above-mentioned multifunctional grafting agent is used at the time of polymerization of the soft layer, a cross-linking structure of the soft layer (b) is generated to a certain extent. Therefore, a polyfunctional crosslinking agent is not an essential component, Is preferably from 0.01 to 5% by mass from the viewpoint of the impact-imparting effect.

The outermost hard layer polymer (c) constituting the multi-layer structure acrylic granular composite contains 80 to 99 mass% of methyl methacrylate and 1 to 5 carbon atoms of the alkyl group in the presence of the innermost hard layer polymer (a) and the soft layer polymer And 1 to 20% by mass of an alkyl acrylate having an alkyl group of 1 to 8 carbon atoms.

Here, the above-mentioned alkyl acrylate is used, but methyl acrylate and ethyl acrylate are preferably used. The ratio of the alkyl acrylate units in the outermost hard layer (c) is preferably from 1 to 20% by mass.

In order to improve the compatibility with the acrylic resin (A), it is also possible to use alkyl mercaptan or the like as a chain transfer agent for controlling the molecular weight at the time of polymerization of the outermost hard layer (c).

Particularly, it is preferable to form a gradient in which the molecular weight of the outermost hard layer gradually decreases from the inside toward the outside, in terms of improving the balance between elongation and impact resistance. As a specific method, it is possible to reduce the molecular weight from the inside toward the outside by dividing the monomer mixture for forming the outermost hard layer into two or more and sequentially increasing the amount of the chain transfer agent added at each time .

The molecular weight to be formed at this time can also be examined by polymerizing the monomer mixture used for each cycle alone under the same conditions and measuring the molecular weight of the obtained polymer.

The particle diameter of the acrylic particulate composite which is preferably used in the present invention is not particularly limited, but is preferably 10 nm or more and 1000 nm or less, more preferably 20 nm or more and 500 nm or less, And most preferably 50 nm or more and 400 nm or less.

The mass ratio of the core to the shell in the acrylic particulate composite which is preferably used in the present invention is not particularly limited, but when the total amount of the multi-layered polymer is 100 parts by mass, the core layer contains 50 parts by mass or more and 90 parts by mass By mass or less, more preferably 60 parts by mass or more and 80 parts by mass or less.

Specific examples of the acrylic particles which are graft copolymerization suitably used as the acrylic particles (C) to be used in the present invention include unsaturated carboxylic acid ester-based monomers, unsaturated carboxylic acid-based monomers, aromatic vinyls And a graft copolymer obtained by copolymerizing a monomer mixture composed of a vinyl monomer and a vinyl monomer copolymerizable therewith, if necessary.

The rubber polymer used for the acrylic particle (C) as the graft copolymer is not particularly limited, but a diene rubber, an acrylic rubber, an ethylene rubber, or the like can be used. Specific examples include polybutadiene, styrene-butadiene copolymer, block copolymer of styrene-butadiene, acrylonitrile-butadiene copolymer, acrylic acid butyl-butadiene copolymer, polyisoprene, butadiene-methyl methacrylate copolymer, Ethylene-methyl acrylate copolymer, methyl methacrylate copolymer, butadiene-ethyl acrylate copolymer, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, ethylene-isoprene copolymer and ethylene-methyl acrylate copolymer. These rubbery polymers may be used alone or in a mixture of two or more.

When the refractive index of each of the acrylic resin (A) and the acrylic resin (C) is approximate, transparency of the acrylic film of the present invention can be obtained.

Specifically, the difference in refractive index between the acrylic particles (C) and the acrylic resin (A) is preferably 0.05 or less, more preferably 0.02 or less, particularly 0.01 or less.

In order to satisfy such a refractive index condition, it is necessary to adjust the composition ratio of each monomer unit of the acrylic resin (A), or to adjust the composition ratio of the rubber polymer or monomer used for the acrylic particle (C) And an acrylic film excellent in transparency can be obtained.

Here, the difference in refractive index means that the acrylic resin (A) sufficiently dissolves the acrylic film of the present invention in an available solvent to obtain a cloudy solution, which is then subjected to centrifugal separation or the like to remove the solvent- (23 ° C, measured wavelength: 550 nm) after separating the insoluble portion (acrylic resin (A)) and insoluble portion (acrylic particle) from the insoluble portion.

In the present invention, the method of blending the acrylic resin (A) with the acrylic resin (C) is not particularly limited. The acrylic resin (A) and other optional components are blended in advance, A method of homogeneously melt-kneading by a single-screw or twin-screw extruder while adding particles is preferably used.

A solution prepared by preliminarily dispersing acrylic particles is added to a solution (dope) in which an acrylic resin (A) is dissolved, and a solution obtained by dissolving and mixing acrylic particles (C) and other optional additives is mixed with a solution Or the like may be used.

Commercially available acrylic particles (C) of the present invention may be used. For example, Metablen W-341 (C2), Chemisnow MR-2G (C3), MS-300X , "Palaloid" (manufactured by Kureha Chemical Industry Co., Ltd.), "Acryloid" (manufactured by Rohm and Haas Company), "Styphiloid" (manufactured by Gansu Kasei Kagaku Kogyo Co., Ltd.), and " "Parapet SA" manufactured by Kuraray Co., Ltd. These may be used alone or in combination of two or more.

In the acrylic film of the present invention, it is preferable to contain the acrylic particles (C) in an amount of 0.1 to 5 mass% with respect to the total mass of the resin constituting the film.

&Lt; Cellulose ester resin (B) >

The acrylic film of the present invention preferably contains a cellulose ester resin (B), particularly from the viewpoints of improvement in brittleness and improvement in heat resistance and further transparency when mixed with the acrylic resin (A), and the cellulose ester resin B), the substitution degree (T) of the acyl group having an acyl group with a total degree of substitution (T) of 2.0 to 3.0 and a carbon number of 3 to 7 is preferably 1.2 to 3.0. That is, the cellulose ester resin (B) is a cellulose ester resin substituted by an acyl group having 3 to 7 carbon atoms. Specifically, propionyl, butyryl and the like are preferably used, and a propionyl group is particularly preferably used.

When the total degree of substitution of the acyl group of the cellulose ester resin (B) is less than 2.0, that is, when the residues of the hydroxyl groups at the 2, 3 and 6 positions of the cellulose ester molecule exceed 1.0, And haze is a problem.

When the substitution degree of the acyl group having 3 to 7 carbon atoms is less than 1.2 even when the total substitution degree of the acyl group is 2.0 or more, sufficient compatibility is not obtained or the brittleness is lowered. For example, even when the total substitution degree of the acyl group is 2.0 or more, when the substitution degree of the acyl group having 2 carbon atoms, that is, the acetyl group is high and the degree of substitution of the acyl group having 3 to 7 carbon atoms is less than 1.2, And the haze is increased. Even when the total substitution degree of the acyl group is 2.0 or more, when the substitution degree of the acyl group having 8 or more carbon atoms is high and the degree of substitution of the acyl group having 3 to 7 carbon atoms is less than 1.2, the brittleness is lowered, I can not get it.

The acyl substitution degree of the cellulose ester resin (B) of the present invention is not particularly limited when the degree of substitution (T) is 2.0 to 3.0 and the substitution degree of the acyl group having 3 to 7 carbon atoms is 1.2 to 3.0, The sum of the acetyl groups and the substitution degrees of the acyl groups having 8 or more carbon atoms is preferably 1.3 or less.

In the present application, the term "acyl group" also includes those having a substituent. Provided that the carbon number of the acyl group includes a substituent of an acyl group.

When the cellulose ester resin (B) has an aromatic acyl group as a substituent, the number of the substituent X to be substituted with an aromatic ring is preferably 0 to 5. Also in this case, it is necessary to ensure that the substitution degree of the acyl group having 3 to 7 carbon atoms including the substituent is 1.2 to 3.0. For example, when the benzyl group has a carbon number of 7, the benzyl group has a carbon number of 8 or more when it has a substituent group containing carbon, and is not included in the acyl group having 3 to 7 carbon atoms.

When the number of the substituents to be substituted with aromatic rings is two or more, they may be the same or different, and they may also be connected to each other to form a condensed polycyclic compound (for example, naphthalene, indene, indane, phenanthrene, quinoline, isoquinoline, , Chroman, phthalazine, acridine, indole, indoline, etc.) may be formed.

In the cellulose ester resin (B), a structure having at least one substituted or unsubstituted aliphatic acyl group having 3 to 7 carbon atoms is used as the structure used in the cellulose resin of the present invention.

The substitution degree of the cellulose ester resin (B) of the present invention is such that the degree of substitution (T) of the acyl group is from 2.00 to 3.00 and the substitution degree of the acyl group having from 3 to 7 carbon atoms is from 1.2 to 3.0.

The sum of the degree of substitution of an acetyl group and an acyl group having 8 or more carbon atoms other than an acyl group having 3 to 7 carbon atoms is preferably 1.3 or less.

The cellulose ester resin (B) of the present invention is preferably at least one selected from among cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate benzoate, cellulose propionate and cellulose butyrate, and particularly preferably cellulose acetate propionate , And cellulose propionate are more preferable.

Among these, particularly preferred cellulose ester resin (B) is cellulose acetate propionate or cellulose acetate butyrate and preferably has an acyl group having 3 or 4 carbon atoms as a substituent.

The part which is not substituted with an acyl group usually exists as a hydroxyl group. These can be synthesized by a known method.

The substitution degree of the acetyl group and the substitution degree of the other acyl group were obtained by the method defined in ASTM-D817-96.

The weight average molecular weight (Mw) of the cellulose ester resin (B) of the present invention is preferably in the range of from 75000 to 28000, particularly preferably in the range of from 100000 to 240000 from the viewpoint of improving the compatibility with the acrylic resin (A) , And particularly preferably from 160,000 to 24,000.

<Commercial State>

In the acrylic film of the present invention, the acrylic resin (A) and the cellulose ester resin (B) are preferably contained in a commercial state at a mass ratio of 100: 0 to 30:70.

Preferably from 95: 5 to 50:50, and more preferably from 90:10 to 60:40.

In the acrylic film of the present invention, it is necessary that the acrylic resin (A) and the cellulose ester resin (B) are contained in a commercial state. The physical properties and quality required for an acrylic film are achieved by making other resins compatible with each other.

Whether or not the acrylic resin (A) and the cellulose ester resin (B) are in a commercial state is determined by the glass transition temperature Tg.

In the case of simple mixing of the two resins, there are two glass transition temperatures of the mixture because the glass transition temperature of each resin is present. However, when both resins are common, the inherent glass transition temperature is lost , One glass transition temperature is obtained and the glass transition temperature of the commonly used resin is obtained.

It is known that the glass transition temperature T _g1,2 of the mixture in this commercial state can be _approximated by the Gordon-Taylor equation (M. Gordon and JS Taylor, 2 J. Of Applied Chem. 493-500 (1952)) have.

_{T g1, 2 = (w 1} T g1 + Kw 2 T g2) / (w 1 + Kw 2)

Where w ₁ and w ₂ are mass fractions of component 1 (acrylic resin (A)) and 2 (cellulose ester resin (B)); T _g1 and T _g2 are the glass transition temperature (Kelvin temperature) of components 1 and 2, respectively; T _g1 , ₂ is the glass transition temperature of the mixture of constituents 1 and 2; K is a constant relating to the free volume of the two resins.

The acrylic resin (A) and the cellulose ester resin (B) are preferably amorphous resins, and either one of them may be a crystalline polymer or a polymer having partial crystallinity. In the present invention, The cellulose ester resin (B) is preferably used as the amorphous resin.

A mixed resin obtained by polymerizing a precursor of an acrylic resin (A) such as a monomer, a dimer, or an oligomer after mixing it with a cellulose ester resin (B) often undergoes graft polymerization, cross-linking reaction or cyclization reaction, And often can not be melted by heating, and this does not apply to resins contained in the commercial state of the present invention.

The total mass of the acrylic resin (A) and the cellulose ester resin (B) in the acrylic film of the present invention is preferably 55% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% Mass% or more.

When resins other than the acrylic resin (A), the cellulose ester resin (B) and the acrylic particles (C) are used, it is preferable to adjust the addition amount within a range that does not impair the function of the acrylic film of the present invention.

Examples of the resin other than the acrylic resin (A), the cellulose ester resin (B) and the acrylic particle (C) include polystyrene, polyvinyl acetate, polyolefin, polycarbonate and the like.

<Other additives>

As the other additives, the acrylic film of the present invention may contain an ultraviolet absorber, a retardation control agent, a matting agent, and an antioxidant.

<Ultraviolet absorber>

In the present invention, the ultraviolet absorbing system may be used alone or in combination.

Among ultraviolet absorbers, an ultraviolet absorber having a molecular weight of 400 or more is hardly volatilized at a high boiling point, and it is difficult to scatter even at a high temperature molding, so that the addition of a relatively small amount can effectively improve weather resistance. In addition, the transition from a thin coating layer to a substrate layer is particularly small, and it is difficult to precipitate on the surface of the laminated plate, so that the amount of the ultraviolet absorber contained is maintained for a long time, and the durability improvement effect is preferable.

Among these compounds, preferred are 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2-benzotriazole, 2,2- -Tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol] is particularly preferred.

In the present invention, conventionally known ultraviolet absorbent polymers may also be used. Examples of conventionally known ultraviolet absorbent polymers include, but are not limited to, polymers obtained by homopolymerizing RUVA-93 (Otsuka Chemical) and polymers obtained by copolymerizing RUVA-93 and other monomers.

Specifically, PUVA-30M, which is a copolymer of RUVA-93 and methyl methacrylate in a ratio of 3: 7 (by mass ratio), and PUVA-50M, which is copolymerized in a ratio of 5: 5 by mass.

(Phase difference control agent)

In the present invention, as the retardation control agent, compounds described in JP-A-2002-296421 and various ester plasticizers can be used. Hereinafter, the preferred ester compounds will be described in detail.

In the present invention, among the various compounds to be described later, a compound having a structure in which an aromatic ring is arranged in a plane is particularly preferable when it is added as an additive and stretched.

For this reason, a compound in which an aromatic ring is contained as a block in the main chain or at the terminal is preferable.

<Polyester Polyol>

Examples of the polyester polyol used in the present invention include a dehydration condensation reaction of a glycol having an average carbon number of 2 to 3.5 with a dibasic acid having an average carbon number of 4 to 5.5 or a dehydration condensation reaction of the glycol with an anhydrous dibasic salt having an average carbon number of 4 to 5.5 Addition of a base and dehydration condensation reaction are preferred.

As the glycol and dibasic acid constituting the polyester polyol used in the present invention, a combination in which the average of the average number of carbon atoms in glycol and the average number of carbon atoms in dibasic acid is 6 to 7.5 is preferable.

The polyester polyol obtained from the glycol and the dibasic acid may have a number average molecular weight in the range of 1000 to 200000, more preferably 1000 to 5000, basically a hydroxyl-terminated polyester, and a polyester having a number average molecular weight of 1200 to 4000 Is particularly preferably used.

By using a polyester polyol having a number average molecular weight within this range, a phase difference control agent (modifier for cellulose ester) having excellent compatibility with cellulose ester can be obtained in the solid phase reaction.

From the viewpoint of achieving the effects of the present invention, it is preferable that the polyester polyol having a number average molecular weight of 1,000 or more is contained in the film in an amount of 2 to 30 mass% from the viewpoint of retardation development, compatibility, moisture permeability and the like. More preferably 10 to 20% by mass.

In practice, the content of the polymer in the film is determined depending on the kind of the polymer and the weight average molecular weight depending on the performance such as dimensional stability, retentivity and transmittance in the range of not dying in the dope, on the web, and after the film formation .

On the other hand, from the viewpoint of the effect of the present invention, the content of the carboxyl group end in the polyester polyol used in the present invention is preferably 1/20 or less of the hydroxyl group terminal end, and more preferably 1/40 or less desirable.

&Lt; Aromatic terminal ester plasticizer >

As the retardation control agent of the present invention, an aromatic terminal ester plasticizer represented by the following formula (I) may be used.

(I)

G is an alkylene glycol residue having 2 to 12 carbon atoms or an aryl glycol residue having 6 to 12 carbon atoms or an oxyalkylene glycol residue having 4 to 12 carbon atoms, A is an alkylene glycol residue having 4 to 12 carbon atoms, An alkylene dicarboxylic acid residue of 12 to 12 carbon atoms or an aryl dicarboxylic acid residue of 6 to 12 carbon atoms, and n represents an integer of 1 or more.

In formula (I), an alkylene glycol residue or an oxyalkylene glycol residue or an aryl glycol residue represented by G, a benzene monocarboxylic acid residue represented by B, an alkylenedicarboxylic acid residue represented by A, or an aryldicarboxylate residue An acid residue, and is obtained by a reaction such as a conventional polyester-based plasticizer.

Examples of the benzene monocarboxylic acid component of the aromatic terminal ester plasticizer of the present invention include benzoic acid, benzoic acid, para-tert-butylbenzoic acid, orthotoluenic acid, Aminobenzoic acid, and acetoxybenzoic acid. These may be used alone or in combination of two or more.

Hereinafter, specific compounds of the aromatic terminal ester plasticizer of the present invention are shown, but the present invention is not limited thereto.

The content of the aromatic terminal ester plasticizer of the present invention is preferably 1 to 20 mass%, more preferably 3 to 11 mass%, in the cellulose ester film.

<Polyvalent alcohol ester>

In the present invention, a polyvalent alcohol ester plasticizer can also be used as the retardation control agent.

The polyhydric alcohol ester used in the present invention is preferably an ester of a divalent or higher aliphatic polyhydric alcohol and a monocarboxylic acid and having an aromatic ring or a cycloalkyl ring in the molecule.

The polyhydric alcohol used in the present invention is represented by the following formula (1).

Wherein n is an integer of 2 or more, and the OH group represents an alcoholic or phenolic hydroxyl group.

Examples of preferred polyhydric alcohols include, for example, the following.

Propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,2-butanediol, 1,2-butanediol, 1,3-propanediol, Butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, galactitol, mannitol, 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylol propane, trimethylol ethane, xylitol and the like.

Among them, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylol propane and xylitol are preferable.

The monocarboxylic acid used in the polyhydric alcohol ester of the present invention is not particularly limited, and known aliphatic monocarboxylic acids, alicyclic monocarboxylic acids, aromatic monocarboxylic acids, and the like can be used.

The use of an alicyclic monocarboxylic acid or an aromatic monocarboxylic acid is preferable in terms of improving moisture permeability and retention. Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto.

As the aliphatic monocarboxylic acid, a straight chain or branched chain fatty acid having 1 to 32 carbon atoms can be preferably used.

More preferably from 1 to 20 carbon atoms, and particularly preferably from 1 to 10 carbon atoms. Use of acetic acid increases the compatibility with the cellulose ester, and it is also preferable to use acetic acid and other monocarboxylic acids in combination.

Preferred aliphatic monocarboxylic acids are acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethylhexanecarboxylic acid, undecylic acid, lauric acid But are not limited to, trimellitic acid, trimellitic acid, trimellitic acid, tridecylic acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, Unsaturated fatty acids such as malic acid, melissic acid and lactic acid, and unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid and arachidonic acid.

Examples of preferred alicyclic monocarboxylic acids include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid and derivatives thereof.

Examples of preferred aromatic monocarboxylic acids include those obtained by introducing an alkyl group into a benzene ring of a benzoic acid such as benzoic acid or toluic acid, a benzene ring such as biphenylcarboxylic acid, naphthalenecarboxylic acid or tetralinecarboxylic acid, Or an aromatic monocarboxylic acid having at least two or more aromatic monocarboxylic acids or derivatives thereof. In particular, benzoic acid is preferred.

The molecular weight of the polyhydric alcohol ester is not particularly limited, but is preferably in the range of 300 to 1500, more preferably in the range of 350 to 750.

The larger molecular weight is preferable because it is less likely to be volatilized. The smaller the molecular weight is, the better the moisture permeability and the compatibility with the cellulose ester are.

The carboxylic acid used for the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. Further, the OH group in the polyhydric alcohol may be all esterified, or a part thereof may be left in the OH group state.

Specific compounds of polyhydric alcohol esters are shown below.

&Lt; Diester compound &

The retardation control agent of the present invention is preferably an acrylic film containing a sugar ester compound obtained by esterifying a hydroxyl group of a sugar compound having 1 to 12 of at least one kind of structures selected from a furanose structure and a pyranose structure.

Examples of the sugar compound of the present invention include glucose, galactose, mannose, fructose, xylose, arabinose, lactose, sucrose, cellobiose, cellulose, maltotriose and raffinose. It is preferable to have both a furanose structure and a pyranose structure.

Wherein the ester compound is a benzoic acid ester of a monosaccharide (? -Glucose,? -Fructose), or an arbitrary 2 of a monosaccharide -OR ₁₂ , -OR ₁₅ , -OR ₂₂ or -OR ₂₅ represented by the following formula Is preferably a benzoic acid ester of a polysaccharide having m + n = 2 to 12 produced by dehydration condensation of at least two sites.

The sugar ester compound of the present invention is one in which some or all of the hydroxyl groups of the sugar compound are esterified or a mixture thereof.

The benzoic acid in the above formula may also have a substituent, and examples thereof include an alkyl group, an alkenyl group, an alkoxyl group and a phenyl group, and the alkyl group, alkenyl group and phenyl group may have a substituent.

In order to suppress the fluctuation of the retardation value and to stabilize the display quality, the acrylic film of the present invention preferably contains the ester compound in an amount of 1 to 30 mass% of the total amount of the resins constituting the acrylic film.

The sugar ester compound of the present invention is commercially available as Monopet SB (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.).

&Lt; Other retardation controller >

As the retardation control agent of the present invention, it is also preferable that bisphenol A is contained in the molecule. A compound obtained by adding ethylene oxide or propylene oxide to both ends of bisphenol A, and the like can be used.

For example, BP series BPE-20 (F), BPE-20NK, BPE-20T, BPE-40, BPE-60 and BPE-100 such as Newpol BP-2P, BP-3P, BP- BPE series such as BPE-180 (manufactured by Sanyo Chemical Industries, Ltd.) and BPX series such as Adeka polyether BPX-11, BPX-33 and BPX-55 (manufactured by ADEKA CORPORATION).

Bisphenol A bisphenol A, dimetalyl bisphenol A, tetrabromobisphenol A substituted with bisphenol A by bromine or the like, oligomer or polymer thereof, bisphenol A bis (diphenylphosphate) substituted with diphenylphosphate, etc. may also be used .

A polycarboxylate obtained by polymerizing bisphenol A, a polyarylate obtained by polymerizing bisphenol A with a dibasic acid such as terephthalic acid, an epoxy oligomer or polymer obtained by polymerization with a monomer containing an epoxy, and the like.

Modifer CL130D or L440-G, in which bisphenol A is graft-polymerized with styrene or styrene acryl, can also be used.

The acrylic film of the present invention may contain two or more kinds of retardation control agents. In this case, the elution of the retardation control agent may be reduced by optimizing the combination.

The reason for this is not clear, but it is considered that the addition amount per one kind can be reduced and the elution is inhibited by the interaction between the two kinds of retardation control agents and the composition containing the acrylic resin (A).

<Antioxidant>

In the present invention, a commonly known antioxidant may be used.

In particular, lactone, sulfur, phenol, double bond, hindered amine and phosphorous compounds can be preferably used.

For example, those commercially available from Shiba Japan Ltd. under the trade names of "IrgafosXP40" and "IrgafosXP60".

As the phenolic compound, those having a structure of 2,6-dialkylphenol are preferable, and examples thereof include " Irganox1076 ", "Irganox1010 ", ADEKA" Adekastab AO- Quot; under the trade name "

ADK STAB PEP-24G "," ADK STAB PEP-36 ", and" ADK STAB 3010 "from ADEKA, "IRGAFOS P-EPQ" from Kabushiki Kaisha, and "GSY-P101" from Sakaikagaku Kogyo Co., Ltd. are preferable.

The hindered amine compound is preferably commercially available from, for example, Shiba Japan Ltd. under the trade name of "Tinuvin 144" and "Tinuvin 770" from ADEKA, "ADK STAB LA-52" from Kabushiki Kaisha.

The sulfur-containing compound is preferably commercially available from Sumitomo Chemical Co., Ltd. under the trade names "Sumilizer TPL-R" and "Sumilizer TP-D".

The double bond compound is preferably commercially available from Sumitomo Chemical Co. under the trade name of "Sumilizer GM" and "Sumilizer GS".

It is also possible to incorporate a compound having an epoxy group as described in U.S. Patent No. 4,137,201 as an acid capturing agent.

These antioxidants and the like are appropriately added in accordance with the process used in the regeneration, but are generally added in the range of 0.05 to 20% by mass, preferably 0.1 to 1% by mass, based on the resin as the main raw material of the film do.

These antioxidants can obtain a synergistic effect by using a combination of several different system compounds rather than only one kind of antioxidant. For example, a combination of a lactone system, phosphorus system, phenol system system and double bond system system is preferable.

<Mat>

The acrylic film of the present invention preferably contains fine particles as a matting agent.

Examples of the inorganic compound used in the present invention include inorganic fine particles such as silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, Magnesium silicate and calcium phosphate. Further, fine particles of an organic compound can also be preferably used.

Examples of the organic compound include polytetrafluoroethylene, cellulose acetate, polystyrene, polymethyl methacrylate, polypropyl methacrylate, polymethyl acrylate, polyethylene carbonate, acryl styrene resin, silicone resin, polycarbonate resin , And organic polymer compounds such as benzoguanamine type resin, melamine type resin, polyolefin type powder, polyester type resin, polyamide type resin, polyimide type resin, polyfluorinated ethylene type resin and starch .

A polymer compound synthesized by a suspension polymerization method, a polymer compound formed into a spherical shape by a spray drying method or a dispersion method, or an inorganic compound can be used.

The fine particles include silicon, which is preferable in that turbidity is low, and silicon dioxide is particularly preferable.

The average particle diameter of the primary particles of the fine particles is preferably 5 to 400 nm, more preferably 10 to 300 nm.

These particles may be mainly contained as secondary aggregates having a particle diameter of 0.05 to 0.3 탆, and particles having an average particle diameter of 100 to 400 nm are preferably contained as primary particles without aggregation.

The content of these fine particles in the film is preferably 0.01 to 1% by mass, more preferably 0.05 to 0.5% by mass. In the case of a polarizing plate protective film having a multi-layer structure formed by a covalent bonding method, it is preferable that the surface contains fine particles in the added amount.

Examples of the silicon dioxide fine particles include those commercially available under the trade names AEROSIL R972, R972V, R974, R812, 200, 200V, 300, R202, OX50 and TT600 (manufactured by Nippon Aerosil Co., Ltd.) Can be used.

As the fine particles of zirconium oxide, for example, those commercially available under the trade names AEROSIL R976 and R811 (available from NIPPON AEROSIL CO., LTD.) Can be used.

Examples of the polymer include a silicone resin, a fluororesin, and an acrylic resin. Silicone resin is preferable, and it is particularly preferable to have a three-dimensional network structure. For example, it is preferable to use a silicone resin having a three-dimensional network structure such as Tosperp 103, Tospel 105, Tospel 108, Tospel 120, Tospel 145, Tospel 3120, (Trade name) available from Toshiba Silicone Co., Ltd. may be used.

Among them, Aerosil 200V and Aerosil R972V are particularly preferably used because they have a low effect of lowering the friction coefficient while keeping the turbidity of the polarizing plate protective film low. In the polarizing plate protective film used in the present invention, it is preferable that the coefficient of dynamic friction of at least one surface is 0.2 to 1.0.

Various additives may be added to the dope, which is a solution before the film formation, or an additive solution may be separately prepared and added in-line.

Particularly, in order to reduce the load on the filter medium, particulates are preferably added in in-line to a part or the whole amount.

In order to perform inline addition and mixing in the present invention, for example, an inline mixer such as a static mixer (manufactured by TORAY ENGINEERING) or an SWJ (Toray stationary type in-line mixer Hi-Mixer) is preferably used.

<Other additives>

In the acrylic film of the present invention, a plasticizer may be used in combination to improve the fluidity and flexibility of the composition. Examples of the plasticizer include a phthalate ester, a fatty acid ester, a trimellitate ester, a phosphate ester, a polyester, and an epoxy.

Examples of the phosphate ester plasticizer include triphenyl phosphate, tricresyl phosphate, cresyldiphenyl phosphate, octyldiphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate and the like. Examples of the phthalate ester plasticizer include diethyl phthalate, Dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate and di-2-ethylhexyl phthalate.

Of these, polyester-based and phthalate ester-based plasticizers are preferably used. The polyester-based plasticizer is superior to the phthalate ester-based plasticizer such as dioctyl phthalate in non-planarity and extrusion resistance, but the plasticizing effect and compatibility are somewhat deteriorated.

Therefore, these plasticizers may be selected or used in combination according to the application, so that they can be applied to a wide variety of uses.

The polyester plasticizer is a reaction product of a mono- to tetravalent carboxylic acid and a mono- to hexavalent alcohol, but mainly one obtained by reacting a divalent carboxylic acid with a glycol is used. Representative divalent carboxylic acids include glutaric acid, itaconic acid, adipic acid, phthalic acid, azelaic acid, sebacic acid, and the like.

Particularly, when adipic acid, phthalic acid or the like is used, excellent plasticizability can be obtained. Examples of glycols include glycols such as ethylene, propylene, 1,3-butylene, 1,4-butylene, 1,6-hexamethylene, neopentylene, diethylene, triethylene and dipropylene. These dicarboxylic acids and glycols may be used singly or in combination.

The ester-based plasticizer may be any of esters, oligoesters, and polyesters. The molecular weight is preferably in the range of 100 to 10000, but preferably in the range of 600 to 3000, the plasticizing effect is significant.

The viscosity of the plasticizer is related to the molecular structure and the molecular weight, but in the case of the adipic acid-based plasticizer, the range of 200-5000 mPa ((25 캜) is preferable from the viewpoint of compatibility and plasticization efficiency. In addition, several polyester plasticizers may be used in combination.

The plasticizer is preferably added in an amount of 0.5 to 30 parts by mass based on 100 parts by mass of the composition containing the acrylic resin (A). When the addition amount of the plasticizer exceeds 30 parts by mass, the surface is sticky, which is not preferable for practical use. These plasticizers may be used alone or in combination of two or more.

In addition, various kinds of antioxidants may be added to the acrylic resin (A) used in the acrylic film of the present invention in order to improve the thermal decomposition property and heat coloring property during molding. It is also possible to add an antistatic agent to impart an antistatic property to the acrylic film.

As the acrylic resin (A) composition of the present invention, a flame retardant acrylic resin composition containing a phosphorus flame retardant may be used.

Examples of the phosphorus-based flame retardant used herein include triaryl phosphoric acid esters, diaryl phosphoric acid esters, monoaryl phosphoric acid esters, arylphosphonic acid compounds, arylphosphine oxide compounds, condensed aryl phosphoric acid esters, halogenated alkyl phosphoric acid esters, halogen-containing condensed phosphoric acid esters , A halogen-containing condensed phosphonic acid ester, a halogen-containing phosphorous acid ester, and the like, or a mixture of two or more thereof.

Specific examples thereof include triphenyl phosphate, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, phenylphosphonic acid, tris (β-chloroethyl) phosphate, tris (dichloropropyl) Tris (tribromoneopentyl) phosphate, and the like.

<Formation of Acrylic Film>

A preferred example of the production method by the solution casting film-forming method of the acrylic film of the present invention will be described.

(Organic solvent)

The organic solvents useful for forming the dope when the acrylic film of the present invention is prepared by the solution casting method are the mixed solvents containing the solvents A and B.

A dope composition is prepared by dissolving at least a total of 15 to 45 mass% of three kinds of acrylic resin (A), acrylic particle (C), and optionally cellulose ester resin (B) in the mixed solvent.

1) Dissolution Process

The dissolution may be carried out at atmospheric pressure, at a temperature not higher than the boiling point of the main solvent, by pressurizing at a temperature higher than the boiling point of the main solvent, in JP-A 9-95544, JP-A 9-95557, Various methods such as a method of carrying out by a cooling dissolution method as disclosed in JP-A-9-95538 and a method of carrying out at a high pressure as described in JP-A-11-21379 can be used. In particular, It is preferable to perform the method by pressing.

Additives are added to the dope during or after dissolution, dissolved and dispersed, filtered with a filter, defoamed, and sent to the next process with a pump.

It is preferable to use a filtration material having a collection particle diameter of 0.5 to 5 占 퐉 and a filtration time of 10 to 25 sec / 100 ml.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a view schematically showing a dope producing process, a softening process and a drying process of a solution casting film-forming method preferable in the present invention.

If necessary, large aggregate is removed from the acrylic particle charging kiln 41 by the filter 44, and is sent to the storage kiln 42. Thereafter, the acrylic particle addition liquid is added to the main dope melting furnace (1) from the storage kiln (42).

Thereafter, the main dope liquid is filtered in the main filter 3, and the ultraviolet absorbent added liquid is added inline from the conduit 16.

In most cases, the main dope may contain about 10 to 50 mass% of a return material. The recycled material may contain acrylic particles. In this case, it is preferable to control the addition amount of the acrylic particle addition liquid in accordance with the addition amount of the semi-solid material.

The semi-finished product is a product obtained by finely grinding an acrylic film. The acrylic film raw material is produced by cutting out both side portions of the film, which is generated when an acrylic film is formed, or by speckling or the like.

It is also preferable to preliminarily knead the acrylic resin (A), the acrylic particles (C) and, if necessary, the cellulose ester resin (B) into pellets.

2) Flexible process

An endless metal belt 31 that feeds the dope to the pressure die 30 through a feed pump (for example, a pressurized metering gear pump) and feeds the endlessly, for example, a stainless steel belt or a rotating metal drum In a flexible position on a metal support of a press die slit.

It is preferable to use a press die which can adjust the slit shape of the nipping portion of the die and make the film thickness uniform. The pressure die includes a coat hanger die and a T die, all of which are preferably used. The surface of the metal support is mirror-finished.

Two or more pressure dies may be provided on the metal support to increase the film forming speed, and the doping amount may be divided into two or more layers. Alternatively, it is also preferable to obtain a laminated film by a covalent bonding method in which a plurality of doughs are simultaneously flexible.

3) Solvent evaporation process

A web (a dope film formed by softly dope a dope on a flexible support is called a web) is heated on a flexible support to evaporate the solvent to produce a film shape.

In order to evaporate the solvent, there are a method of blowing air from the web side or a method of transferring heat from the back surface of the support by liquid, a method of transferring heat from the front and back by radiant heat, desirable. Also, a method of combining them is also preferably used.

It is preferable to dry the web on the supporter after the softening on the support in an atmosphere of 40 to 100 캜. In order to maintain the temperature at 40 to 100 DEG C, it is preferable to warm the warm air at this temperature to the upper surface of the web or to heat it by means of infrared rays or the like.

From the standpoint of surface quality, moisture permeability and releasability, it is preferable to peel the web from the support within 30 to 120 seconds.

4) Peeling process

And peeling the web from which the solvent has evaporated on the metal support at the peeling position. The stripped web is sent to the next process.

The temperature at the peeling position on the metal support is preferably 10 to 40 占 폚, more preferably 11 to 30 占 폚.

The amount of residual solvent at the time of peeling the web on the metal support at the time of peeling is desirably peeled in the range of 50 to 120 mass% depending on the strength of the drying condition, the length of the metal support, etc. However, The amount of the residual solvent at the time of peeling is determined in accordance with the balance between the economical speed and the quality, since the flatness is deteriorated when peeling off or the peeling tension or dragging or vertical wrinkling is likely to occur.

The residual solvent amount of the web which is the residual solvent of the present invention is defined by the following formula.

Residual solvent amount (%) = (mass before heat treatment of web-mass after heat treatment of web) / (mass after heat treatment of web) 占 100

The heat treatment at the time of measuring the residual solvent amount means that the heat treatment is performed at 140 占 폚 for 2 hours.

When the metal support and the film are peeled off, the peeling tension is usually 196 to 245 N / m. In the case where wrinkles are likely to occur at peeling, peeling is preferably carried out with a tension of 190 N / m or less, To 166.6 N / m, and subsequently to the lowest tension to 137.2 N / m, particularly preferably to the lowest tension to 100 N / m.

In the present invention, the temperature at the peeling position on the metal support is preferably -50 to 40 占 폚, more preferably 10 to 40 占 폚, and most preferably 15 to 30 占 폚.

5) Drying process

After peeling, a drying device 35 for conveying the web alternately in a plurality of rolls arranged in a drying apparatus and conveying the web, and / or a tenter stretching device 34 for clipping and conveying both ends of the web with clips, Dry.

Drying means generally blows hot air on both sides of the web, but there is also a means of heating the microwave instead of the wind. Too rapid drying tends to impair the planarity of the finished film.

It is preferable to dry it at 40 to 160 캜 throughout the entire process, and the residual solvent is adjusted to 5 to 50% by mass in this process.

6) Heat treatment process

It is preferable to heat-treat the film with the residual solvent adjusted to 5 to 50 mass% in the drying process at an apparent Tg + 10 to 90 占 폚, and more preferably perform the treatment at an apparent Tg + 40 to 90 占 폚 . Specifically, it is 80 to 160 ° C.

As a method of treatment, steps may be performed separately, for example, by first carrying out treatment at about 120 캜 and finally heating at 140 캜.

The heat treatment time is preferably 15 minutes to 60 minutes, and particularly preferably 20 minutes to 40 minutes.

In this heat treatment step, drying is also carried out at the same time, and it is preferable that the residual solvent amount of the acrylic film coming out of the present step is less than 1.0% by mass.

7) Stretching process

In the present invention, a stretching step may be provided after the heat treatment.

When the tenter stretching device is used, it is preferable to use a device capable of independently controlling the gripping length of the film (the distance from the start of gripping to the end of gripping) by the left and right gripping means of the tenter. In addition, in the tenter process, it is also preferable to make a compartment having a different temperature intentionally to improve the planarity.

It is also preferable to provide a neutral band so that the respective compartments do not cause interference between different temperature compartments.

Further, the stretching operation may be divided into multiple steps, or biaxial stretching in the machine direction and the width direction is preferably performed. In the case of biaxial stretching, simultaneous biaxial stretching may be performed, or may be performed stepwise.

In this case, the term "stepwise" means that, for example, other stretching in the stretching direction can be carried out sequentially, stretching in the same direction can be divided into multiple steps, and stretching in another direction can be applied to either of the steps . That is, for example, the following stretching step is also possible.

- Stretching in the flexible direction - Stretching in the width direction - Stretching in the flexible direction - Stretching in the flexible direction

- stretching in the width direction - stretching in the width direction - stretching in the softening direction - stretching in the softening direction

Also, simultaneous biaxial stretching may include stretching in one direction and shrinking the other by relaxing the tension. The preferred stretching magnification of the simultaneous biaxial stretching can be in the range of 1.01 times to 1.5 times in both the width direction and the longitudinal direction.

The temperature condition at the time of stretching is preferably performed at an apparent Tg of the acrylic film of 10 to 50 캜. Concretely, it is preferably carried out at 80 to 160 ° C.

In the tenter process, it is preferable that the temperature distribution in the width direction of the atmosphere is small from the viewpoint of enhancing the uniformity of the film. The temperature distribution in the width direction in the tenter process is preferably within ± 5 ° C, More preferably within ± 1 ° C.

8) Winding Process

After the amount of the residual solvent in the web becomes 2 mass% or less, the film is wound up as an acrylic film by a winder 37. When the residual solvent amount is 0.4 mass% or less, a film having good dimensional stability can be obtained.

As the winding method, those generally used may be used, and examples thereof include a static torque method, a constant tension method, a taper tension method, and an internal stress constant program tension control method, and they may be used separately.

The acrylic film of the present invention is preferably a long film, specifically about 100 m to 5000 m, and is usually provided in a roll shape. Further, the width of the film is preferably 1.3 to 4 m, more preferably 1.4 to 2 m.

The film thickness of the acrylic-containing film of the present invention is not particularly limited, but it is preferably 20 to 200 占 퐉, more preferably 25 to 100 占 퐉, and more preferably 30 to 80 占 퐉 in the case of the polarizing plate protective film to be described later Particularly preferred.

<Physical Properties of Acrylic Film>

Hereinafter, the characteristics of the acrylic film of the present invention will be described.

<Photoelastic Coefficient>

The acrylic film of the present invention is preferably adjusted to have a photoelastic coefficient of -6.0 x 10 ^-12 to 6.0 x 10 ^-12 / Pa, and is controlled to be in the range of -2.0 x 10 ^-12 to 2.0 x 10 ^-12 / Is particularly preferable.

In the present invention, in order to adjust the photoelastic coefficient to the above-mentioned range, the ratio of the acrylic resin (A) to the cellulose ester resin (B) and other resins is adjusted and the combination of the retardation control agent and the And adjusting the amount of addition to optimize the composition of the acrylic film.

By adjusting the photoelastic coefficient to such a range, even when stress is applied to the retardation film when the panel is heated to a high temperature or when the ambient atmosphere is high temperature and high humidity, the retardation is hardly expressed and image unevenness is reduced . It is also possible to reduce the image unevenness that occurs in a long-term use.

<Water vapor permeability>

The acrylic film of the present invention is measured under the conditions of a temperature of 40 占 폚 and a humidity of 90% RH on the basis of JIS Z 0208, and the value of the moisture permeability in terms of the film thickness ratio of 60 占 퐉 is preferably 50 to 600 g / m2 占 24 h , And particularly preferably 200 to 450 g / m 2 24 h.

When the acrylic film of the present invention is used on at least one side of the polarizing plate, by setting the moisture permeability within the above range, light leakage and image quality deterioration due to deterioration of the polarizer do not occur even when the liquid crystal display device is used under a high humidity environment, Is used under a high temperature environment and is used outdoors at a high illuminance to increase the luminance of the backlight, so that deterioration or deformation of the polarizer due to vapor generated even when exposed to high temperature can be suppressed.

<Others>

The acrylic film of the present invention has one defect per square of 10 cm in diameter with a defect of 5 m or more in diameter in the film plane. More preferably not more than 0.5 per square of a 10 cm side, and even more preferably not more than 0.1 per square of a side of 10 cm.

Here, the diameter of the defect refers to the diameter of the defect when the defect is circular, and when the defect is not circular, the range of defect is determined by observing with a microscope by the following method, and its maximum diameter (diameter of the circumscribed circle) is determined.

The range of the defect is the size of the shadow when the defect is observed as the transmitted light of the differential interference microscope when the defect is bubble or foreign matter. When the defect is a change in surface shape such as transfer of roll damage or scratches, the size is confirmed by observing the defect as reflected light of a differential interference microscope.

In the case of observing with reflected light, if the size of the defect is unclear, aluminum or platinum is deposited on the surface and observed.

In order to obtain a film having excellent durability exhibited by such defect frequency with high productivity, it is necessary to precisely filter the polymer solution just before bending, to increase the cleanliness around the bubble, and to set the drying conditions after bending stepwise It is also effective to suppress the foaming and dry it.

If the number of defects is more than one per square of 10 cm on one side, for example, if a tensile force is applied to the film at the time of processing in a later process, etc., the film breaks from the defect as a starting point, have. When the diameter of the defect is 5 mu m or more, it can be visually confirmed by observation of the polarizing plate or the like, and a bright spot may be generated when the defect is used as an optical member.

In addition, even when the film can not be visually confirmed, when a hard coat layer or the like is formed on the film, the coating agent can not be formed uniformly, resulting in a defect (coating missing). Here, the defect refers to a defect in the film due to cavitation (foaming defect) in the film caused by the rapid evaporation of the solvent in the step of drying the solution film formation, a foreign substance in the film forming solution and foreign substances contained in the film Defects).

Further, the acrylic film of the present invention preferably has a tensile elongation at least in one direction of 10% or more, more preferably 20% or more, in the measurement according to JIS-K7127-1999.

The upper limit of the elongation at break is not particularly limited, but it is practically about 250%. In order to increase the elongation at break, it is effective to suppress defects in the film due to foreign substances or foaming.

The thickness of the acrylic film of the present invention is preferably 20 占 퐉 or more. More preferably 30 mu m or more.

Although the upper limit of the thickness is not particularly limited, when the film is formed by a solution casting method, the upper limit is about 250 탆 from the viewpoint of coatability, foaming, solvent drying and the like. The thickness of the film can be appropriately selected depending on the application.

The acrylic film of the present invention preferably has a total light transmittance of 90% or more, and more preferably 93% or more.

The practical upper limit is about 99%. In order to achieve excellent transparency expressed by the total light transmittance, it is necessary to prevent the addition of an additive or a copolymerizable component that absorbs visible light, or to remove foreign matter in the polymer by high-precision filtration to reduce diffusion or absorption of light inside the film Valid.

It is also possible to reduce the surface roughness of the film contacting portion (the cooling roll, the calender roll, the drum, the belt, the coating base in the solution film formation, the conveying roll, etc.) during film formation to reduce the surface roughness of the film surface, It is effective to reduce the diffusion and reflection of light on the surface of the film.

The acrylic film of the present invention is characterized by having a haze value (turbidity) of 1.0% or less, which is one of indexes showing transparency. However, it is preferably 0.5% or less in terms of brightness and contrast when assembled in a liquid crystal display.

In order to achieve such a haze value, it is effective to remove foreign substances in the polymer by high-precision filtration to reduce the diffusion of light inside the film.

It is also effective to suppress the surface diameter of the acrylic particles or the addition amount to within the above range, or to reduce the surface roughness of the film contacting portion at the time of film formation, because the surface smoothness is represented by surface haze.

The total light transmittance and the haze value of the acrylic film are values measured according to JIS-K7361-1-1997 and JIS-K7136-2000.

The acrylic film of the present invention can be suitably used as an optical acrylic film provided that the above properties are satisfied.

(Polarizer)

The acrylic film of the present invention can be used as a polarizer protective film. The polarizing plate can be manufactured by a general method.

It is preferable that an adhesive layer is formed on the back side of the acrylic film of the present invention and is bonded to at least one side of the polarizer produced by immersion stretching in an iodine solution.

The above film may be used for the other side, or another polarizing plate protective film may be used. For example, commercially available cellulose ester films (for example, Konica Minolta Tact KC8UX, KC4UX, KC5UX, KC8UY, KC4UY, KC12UR, KC8UCR-3, (Manufactured by Konica Minolta Opto Co., Ltd.) or the like is preferably used.

A polarizer, which is a main component of the polarizer, is a device that allows only light of a polarization plane in a certain direction to pass. A currently known polarizer film is a polyvinyl alcohol polarizer film, which is obtained by dyeing a polyvinyl alcohol film with iodine And dyed dichromatic dyes.

Polarizers are prepared by forming a polyvinyl alcohol aqueous solution, uniaxially stretching it, dyeing it, uniaxially stretching it, and preferably durability treatment with a boron compound.

As the pressure-sensitive adhesive used for the pressure-sensitive adhesive layer, it is preferable that at least a part of the pressure-sensitive adhesive layer has a pressure-sensitive adhesive having a storage elastic modulus at 25 ° C in the range of 1.0 × 10 ⁴ Pa to 1.0 × 10 ⁹ Pa, A curing type pressure-sensitive adhesive which forms a high molecular weight or crosslinked structure by various chemical reactions after bonding is suitably used.

Specific examples thereof include curable pressure sensitive adhesives such as urethane pressure sensitive adhesives, epoxy pressure sensitive adhesives, water based polymer-isocyanate pressure sensitive adhesives, thermosetting acrylic pressure sensitive adhesives, moisture cured urethane pressure sensitive adhesives, polyether methacrylate type, ester methacrylate type, An anaerobic tackifier such as polyether methacrylate, a cyanoacrylate type instantaneous tackifier, and an acrylate and a peroxide type two-component type instant tackifier.

The pressure-sensitive adhesive may be a one-component type, or two or more liquids may be mixed before use.

The pressure-sensitive adhesive may be a solvent based on an organic solvent, or may be a water-based medium such as an emulsion type, a colloidal dispersion type or an aqueous solution type, which is a medium containing water as a main component. The concentration of the pressure-sensitive adhesive liquid may be appropriately determined depending on the thickness of the pressure-sensitive adhesive film, the application method, the application conditions, and the like, and is usually 0.1 to 50 mass%.

(Liquid crystal display device)

The liquid crystal display device having excellent visibility can be manufactured by assembling the polarizing plate bonded with the acrylic film of the present invention on at least one surface of the liquid crystal cell and assembling the liquid crystal display device. The polarizing plate of the present invention is bonded to the liquid crystal cell through the adhesive layer or the like.

The polarizing plate of the present invention is preferably used in LCDs of various driving types such as reflection type, transmission type, transflective type LCD or TN type, STN type, OCB type, HAN type, VA type (PVA type, MVA type) .

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.

&Lt; Example 1 >

(Acrylic resin (A))

The following acrylic resins A1-A7 and MS1 and MS2 were prepared by a known method.

A1: monomer mass ratio (MMA: MA = 98: 2), Tg 103 DEG C, Mw 70000

A2: monomer mass ratio (MMA: MA = 97: 3), Tg 102 DEG C, Mw 160000

A3: monomer mass ratio (MMA: MA = 97: 3), Tg 102 DEG C, Mw350000

A4: monomer mass ratio (MMA: MA = 97: 3), Tg 102 DEG C, Mw 550000

A5: monomer mass ratio (MMA: MA = 97: 3), Tg 102 DEG C, Mw800000

A6: monomer mass ratio (MMA: MA = 97: 3), Tg 102 DEG C, Mw930000

A7: monomer mass ratio (MMA: MA = 94: 6), Tg 99 DEG C, Mw 1100000

MS1: monomer mass ratio (MMA: ST = 60: 40) Tg 103 deg. C, Mw100000

MS2: monomer mass ratio (MMA: ST = 40: 60) Tg 102 deg. C, Mw100000

In addition, the following commercially available products were used.

Dianal BR50 (manufactured by Mitsubishi Rayon Co., Ltd.) Tg 100 占 폚 Mw100000

Dianal BR52 (manufactured by Mitsubishi Rayon Co., Ltd.) Tg 105 deg. C Mw85000

Dianal BR80 (manufactured by Mitsubishi Rayon Co., Ltd.) Tg 105 deg. C Mw95000

Dianal BR83 (manufactured by Mitsubishi Rayon Co., Ltd.) Tg 105 占 폚 Mw40000

Dianal BR85 (manufactured by Mitsubishi Rayon Co., Ltd.) Tg 105 DEG C Mw 280000

Dianal BR88 (manufactured by Mitsubishi Rayon Co., Ltd.) Tg 105 占 폚 Mw480000

80N (manufactured by Asahi Kasei Chemicals Co., Ltd.) Tg 110 占 폚 Mw100000

The ratio of MMA units in the molecule of the commercially available acrylic resin (A) is about 30 mass% for DIANAL BR50, about 70 mass% for DIANAL BR52, and 90 mass% or more and 99 mass% for DIANAL BR80 to 80N %.

(Synthesis of A8)

First, a methyl methacrylate / acrylamide copolymerization system suspension was adjusted as follows.

20 parts by mass of methyl methacrylate

Acrylamide 80 parts by mass

0.3 parts by mass of potassium persulfate

Ion-exchanged water 1500 parts by mass

The reaction was carried out while maintaining the temperature at 70 캜 until the monomer was completely converted into a polymer while the reactor was charged with nitrogen gas and the reactor was replaced with nitrogen gas. The obtained aqueous solution was used as a suspending agent. A solution prepared by dissolving 0.05 parts by mass of the suspension in 165 parts by mass of ion exchanged water into a stainless steel autoclave having a capacity of 5 liters and a baffle and a Fauldler type stirring wing was supplied, Lt; / RTI &gt;

Then, the following mixed materials of the following composition were added while stirring the reaction system.

Methacrylic acid 27 parts by mass

73 parts by mass of methyl methacrylate

t-dodecyl mercaptan 1.2 parts by mass

0.4 parts by mass of 2,2'-azobisisobutyronitrile

After the addition, the temperature was raised to 70 占 폚, and the point of time when the internal temperature reached 70 占 폚 was regarded as the polymerization start point, and the polymerization was continued for 180 minutes.

Thereafter, cooling of the reaction system, separation of the polymer, washing and drying were carried out according to a conventional method to obtain a bead-shaped copolymer. The polymerization rate of the copolymer was 97%, and the weight average molecular weight was 130,000.

0.2% by mass of an additive (NaOCH ₃ ) was added to the copolymer, and nitrogen was purged from the hopper part at a rate of 10 L / min using a twin-screw extruder (TEX 30, L / D = 44.5, A cycling reaction was carried out at a revolution rate of 100 rpm, a feed rate of 5 kg / hr, and a cylinder temperature of 290 DEG C to prepare pellets, which were then vacuum-dried at 80 DEG C for 8 hours to obtain an acrylic resin A8. The weight average molecular weight (Mw) of the acrylic resin A8 was 1,30000 and the Tg was 140 deg.

&Lt; Production of acrylic particles (C1) >

38.2 liters of ion-exchanged water and 111.6 g of sodium dioctylsulfosuccinate were charged into a reactor having an internal volume of 60 liters of a reflux condenser and the temperature was raised to 75 DEG C under a nitrogen atmosphere while stirring at a rotational speed of 250 rpm, It was virtually absent. After stirring for 5 minutes, a monomer mixture consisting of 1657 g of MMA, 21.6 g of BA and 1.68 g of ALMA was added in a batch, and the exothermic peak was detected again for 20 minutes to complete the polymerization of the innermost hard layer.

Subsequently, 3.48 g of APS was added, and after stirring for 5 minutes, a monomer mixture composed of 8105 g of BA, 31.9 g of PEGDA (200) and 264.0 g of ALMA was continuously added over 120 minutes, and the addition was continued for 120 minutes , The polymerization of the soft layer was completed.

Next, 1.32 g of APS was added, and after stirring for 5 minutes, a monomer mixture containing 2106 g of MMA and 201.6 g of BA was continuously added over 20 minutes, and after completion of the addition, the polymerization was further continued for 20 minutes to polymerize the outermost hard layer 1 Completed.

Subsequently, 1.32 g of APS was added, and after 5 minutes, a monomer mixture consisting of 3148 g of MMA, 201.6 g of BA and 10.1 g of n-OM was continuously added over 20 minutes, and the addition was continued for another 20 minutes after completion of the addition. Subsequently, the temperature was raised to 95 캜 and maintained for 60 minutes to complete the polymerization of the outermost hard layer 2.

A small amount of the polymer latex thus obtained was sampled and the average particle diameter was determined by the absorbance method. As a result, it was found to be 0.10 탆 and 100 nm. The remaining latex was added to a 3 mass% sodium sulfate aqueous solution to cause salting and solidification, followed by dehydration and washing repeatedly, followed by drying to obtain acrylic particles (C1) having a three-layer structure.

The above abbreviations are respectively the following materials.

MMA: methyl methacrylate

MA: methyl acrylate

BA: n-butyl acrylate

ALMA: Allyl methacrylate

PEGDA: polyethylene glycol diacrylate (molecular weight 200)

n-OM: n-octyl mercaptan

APS: Ammonium persulfate

<Production of Acrylic Film 1>

(Dope solution composition 1)

Acrylic resin (A) 70 parts by mass of Dianal BR85 (manufactured by Mitsubishi Rayon Co., Ltd.)

Cellulose ester resin (B) CE1 30 parts by mass

Acrylic particles (C) C2 3 parts by mass

Ultraviolet absorber (D) 2 parts by mass of Tinuvin 928 (manufactured by Shiba Japan K.K.)

300 parts by mass of methylene chloride

40 parts by mass of ethanol

The composition was sufficiently dissolved while heating to prepare a dope solution.

(Formation of Acrylic Film 1)

The prepared dope liquid was uniformly plied to a stainless steel band support at a temperature of 22 DEG C and a width of 2 m by using a belt softening device. In the stainless steel band support, the solvent was evaporated until the amount of residual solvent reached 100%, and peeled off on the stainless steel band support with a peel tension of 162 N / m.

The web of the peeled acrylic resin was slit with a width of 1.6 m and then conveyed to a drying step having a tenter function and dried at 135 캜 while being stretched 1.1 times in the width direction.

At that time, the amount of the residual solvent when the stretching was started with the tenter was 30 mass%.

The amount of the residual solvent after the stretching with the tenter was 20 mass%. In this state, the film was transported to the heat treatment step, followed by heat treatment at 120 占 폚 for 15 minutes and then at 140 占 폚 for 15 minutes.

Thereafter, the film was slit to a width of 1.5 m, knurled to 10 mm in width and 5 m in height at both ends of the film, and wound around a core of 15.24 cm in inner diameter at an initial tension of 220 N / m and a final tension of 110 N / m, .

Further, the drawing magnification in the MD direction calculated from the rotating speed of the stainless steel band support and the running speed of the tenter was 1.1 times.

The residual solvent amount of the acrylic film 1 shown in the following Table 2 was 0.1 mass%, the film thickness was 60 탆, and the winding length was 4000 m.

<Production of Acrylic Films 2 to 17 and 15-1 to 15-47>

The types and composition ratios of the acrylic resin (A), the acrylic particles (C), and the cellulose ester resin (B), if any, were changed as shown in Tables 2 and 3 below Similarly, acrylic films 2 to 17 and 15-1 to 15-47 were prepared.

15-2 to 15-47 were prepared with the same solvent composition and amount as in 15-1 (88 parts by mass of methylene chloride, 6 parts by mass of n-butanol and 6 parts by mass of ethanol).

In the cellulose ester resin (B) shown in Table 1, ac represents acetyl group, pr represents propionyl group, bu represents butyryl group, pen represents pentanoyl group, bz represents benzoyl group, hep represents heptanoyl group, oct represents octanoyl group , and ph represents phthalyl group. The &quot; amount &quot; in Table 2 indicates the mass part.

In addition, as comparative examples, a film based on the film described in Example 1 of 1-A and WO 2005/105918 Example 1 of JP-A-2007-10044 was prepared.

"Assessment Methods"

(Total haze: transparency evaluation)

Each of the thus-prepared film samples was subjected to a 24-hour humidity control in an air conditioner at 23 占 폚 and 55% RH in accordance with JIS K-7136 using a haze meter (NDH2000 type, manufactured by Nippon Denshoku Kogyo Co., Ltd.) Lt; / RTI &gt;

(Surface haze%: surface property evaluation)

The surface haze of the acrylic film of the present invention was measured by the following procedure.

(1) The total haze (H) is measured as described above.

(2) On the surface of the acrylic film of the present invention, an adhesive pressure polyethylene terephthalate film coated with an acrylic pressure-sensitive adhesive on one side is attached, and the total haze value H0 is measured with respect to the entirety.

(3) Separately, the total haze value Ht of only the polyethylene terephthalate film having the pressure-sensitive adhesive coated with the acrylic pressure-sensitive adhesive was measured, and the value obtained by subtracting Ht from H0 measured before was taken as the internal haze value Hi (Hi = H0-Ht) .

(4) The value obtained by subtracting the internal haze (Hi) calculated in (3) from the total haze (H) measured in the above (1) is calculated as the surface haze (Hs) of the film (Hs = H-Hi).

(Tensile softening point: heat resistance evaluation)

A sample having a humidity of 24 hours in an air conditioner at 23 DEG C and 55% RH was cut into 120 mm (length) x 10 mm (width) under the same conditions and subjected to tensile test using a tensilon tester (RTC-1225A manufactured by ORIENTEC Co., The temperature was kept at a heating rate of 30 DEG C / min while being stretched by the tensile force of the thermocouple, and the temperature (DEG C) at the point of 9 N was measured three times, and the average thereof was obtained.

(Ductile fracture: brittleness evaluation)

(Width) of 100 mm (length) × 10 mm (width) under the same conditions in a 23 ° C., 55% RH air conditioning room for 24 hours and a curvature radius of 0 mm and a bending angle of 180 And the film was folded and folded once into two with a folding line and a folding line, respectively, and the evaluation was measured five times and evaluated as follows. In addition, the breaking of the evaluation here means that the evaluation is divided into two or more pieces.

○: Not broken at all 5 times

△: Break once in 5 times

X: At least 2 of 5 breaks

(Cutting property: evaluation of manufacturing aptitude)

Each of the acrylic films was touched with a light load tester (manufactured by Toyo Sekisui Co., Ltd.) under the same conditions and subjected to a humidity control in an air conditioner of 23 ° C and 60% RH for 24 hours, and evaluated as follows.

○: The opening surface is very smooth and also torn in a straight line.

△: There is a slight burr on the open side, but it is torn straight.

X: There is a considerable burr on the open side, and it is not torn straight

(Characteristic Evaluation as a Liquid Crystal Display)

<Production of polarizing plate>

A polarizing plate in which each acrylic film was used as a polarizing plate protective film was produced as follows.

A long roll polyvinyl alcohol film having a thickness of 120 占 퐉 was immersed in 100 parts by mass of an aqueous solution containing 1 part by mass of iodine and 4 parts by mass of boric acid and stretched at 50 占 폚 in the carrying direction by 5 times to prepare a polarizer.

Next, the acrylic film 1 produced in Example 1 was subjected to corona treatment using an acrylic adhesive on one side of the polarizer, followed by bonding.

Further, KC8UCR-5 made by Konica Minolta Opto, which is an alkali saponified phase difference film, was bonded to the other side of the polarizer and dried to prepare a polarizing plate P1. Similarly, the polarizing plates P2 to P to 17, 15-1 to 15-47 were produced using the acrylic films 2 to 17, 15-1 to 15-47.

The polarizing plate using the acrylic film of the present invention was excellent in film cutting property and easy to be processed.

<Fabrication of Liquid Crystal Display Device>

Using each of the polarizing plates thus prepared, evaluation of the display characteristics of the acrylic film was carried out.

The polarizing plates on both sides of the 32-type TV AQ-32AD5 manufactured by Sharp Corporation were peeled off, and the polarizing plate thus prepared was placed so that KC8UCR-5 was on the glass surface side of the liquid crystal cell and in the same direction as the previously polarized polarizing plate And an absorption axis was directed so as to produce liquid crystal display devices.

(Variation of viewing angle: Evaluation of heat resistance and moisture resistance as a polarizing plate protective film)

The following evaluations were carried out using the liquid crystal display devices 1 to 17 and 15-1 to 15-47 manufactured as described above.

The viewing angle of the liquid crystal display was measured using an EZ-Contrast 160D manufactured by ELDIM under the environment of 23 占 폚 and 55% RH. Subsequently, the polarizing plate treated at 60 DEG C and 90% RH for 500 hours was similarly measured, and evaluated in three stages according to the following criteria.

?: No change in viewing angle

△: slight change in viewing angle was confirmed

×: Large variation in viewing angle

(Color shift: evaluation of heat resistant moisture resistance as a polarizing plate protective film)

With respect to the liquid crystal display devices 1 to 1, the display was changed to black display in an environment of 23 ° C and 55% RH, and the angle was observed at an angle of 45 °. Subsequently, the polarizing plate treated at 60 DEG C and 90% RH for 500 hours was similarly observed, and color change was evaluated based on the following criteria.

○: No color change at all

△: Color change slightly confirmed

×: Large change in color

The results of the above evaluation are shown in Tables 4 and 5 below.

As shown in Tables 4 and 5, the acrylic film of the present invention exhibited properties of low hygroscopicity, transparency, high heat resistance, and excellent improvement in brittleness. In addition, the polarizing plate and the liquid crystal display manufactured using the acrylic film of the present invention exhibited excellent visibility and color shift.

1: melting pot
3, 6, 12, 15: filter
4, 13: Storage tank
5, 14: Pump pump
8, 16: conduit
10: Ultraviolet absorber input kiln
20: junction pipe
21: Mixer
30: Die
31: metal support
32: Web
33: Peeling position
34: tenter device
35: Roll dryer
41: Particle charging kiln
42: Storage tank
43: pump
44: Filter

Claims (3)

A method for producing an acrylic film containing an acrylic resin (A) and 0.1 to 5 mass% of acrylic particles (C) by a solution casting film forming method, wherein a solvent A (1) And B in an amount of 5 to 50 mass%, and a step of drying the acrylic film at an apparent glass transition temperature of from + 10 ° C. to + 10 ° C. in a state where the residual solvent is 5 to 50 mass% And a step of performing heat treatment in a range of glass transition temperature + 90 占 폚.
(1) boiling point of solvent A + 35 DEG C <boiling point of solvent B
(2) Mass ratio of solvent A to solvent B in the mixed solution A: B = 98: 2 to 70:30 The acrylic film produced by the manufacturing method according to claim 1, wherein no ductile fracture occurs in an atmosphere at 23 占 폚 and 55% RH, and a tensile softening point is 105 to 145 占 폚 and a haze value is less than 1.0%. The acrylic resin composition according to claim 2, wherein the acrylic film is a resin film containing an acrylic resin (A) and a cellulose ester resin (B) in a mass ratio of 95: 5 to 30:70 in a commercial state, (B) has a weight average molecular weight Mw of 75000 or more and 280000 or less, a total substitution degree (T) of an acyl group of 2.0 or more and 3.0 or less, and a carbon number of 3 or less And a degree of substitution of an acyl group of 7 or more is 1.2 or more and 3.0 or less.

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