KR20160119215A - Polarizing plate protective film, method for producing same, polarizing plate and liquid crystal display device - Google Patents

Abstract

Disclosure of the Invention An object of the present invention is to provide a polarizing plate having a high water resistance and heat resistance and suppressing occurrence of bend unevenness of a liquid crystal display device and having good adhesion with polarizers in combination with water- A protective film, a production method thereof, a polarizing plate and a liquid crystal display device. The polarizing plate protective film of the present invention comprises a copolymer (A) obtained by polymerizing an aromatic vinyl monomer and an unsaturated nitrile monomer as a main component of a thermoplastic resin and a copolymer (B) having an imide ring structure in a mass ratio of A: B = 100: 0 to 50:50.

Description

TECHNICAL FIELD [0001] The present invention relates to a polarizing plate protective film, a polarizing plate protective film, a polarizing plate protective film, a polarizing plate protective film, a polarizing plate protective film,

The present invention relates to a polarizing plate protective film, a production method thereof, a polarizing plate and a liquid crystal display device. More specifically, the present invention relates to a polarizing plate protective film having a high water resistance and suppressing the occurrence of bend unevenness of a liquid crystal display device and having good adhesion with a polarizer even when used in combination with water-soluble and active energy ray- A polarizing plate, and a liquid crystal display device.

The polarizing plate provided in the liquid crystal display device generally has a polarizer and a pair of polarizing plate protective films for supporting the polarizer.

As the polarizing plate protective film, a cellulose ester film having high transparency and saponification treatment with an aqueous alkaline solution and having good adhesiveness to a polarizer can be obtained by using a polyvinyl alcohol-based adhesive (also referred to as a water-repellent film in the present application) Has come.

In addition, the cellulose ester film is easy to exhibit desired retardation by an additive or a stretching treatment, and is also used as a retardation film disposed on the liquid crystal cell side.

However, the cellulose ester film has high moisture permeability, for example, when the film thickness is reduced, the amount of water permeation is increased.

In recent years, a liquid crystal display panel (laminate of a polarizing plate / liquid crystal cell / polarizing plate) including a glass substrate having a thin thickness has been demanded with the thinness of a liquid crystal display device. However, when a thin glass substrate is used, There is a problem that the glass substrate tends to bend due to heat or the like.

As a result of studying this cause, it has been found that the moisture contained in the polarizing plate protective film or polarizer constituting the polarizing plate due to the heat of the backlight or the like is lost and is liable to shrink, and by the contracting force of the polarizing plate, The display panel is curved (bent), and as a result, display irregularity (bend unevenness) occurs in the liquid crystal display device.

Therefore, the polarizing plate protective film on the viewer side or the backlight side is required to have water resistance in order to suppress changes in the environment such as temperature and humidity and evaporation of water due to the influence of heat of the backlight.

As a polarizing plate protective film having a high water resistance, it is known to use an acrylic resin film, for example, an optical film using a polymethyl methacrylate film or the like as a polarizing plate protective film (for example, see Patent Document 1).

However, the acrylic resin film is certainly water-resistant. However, as compared with the cellulose ester film, the adhesiveness with the polarizer, which is a polyvinyl alcohol-based resin, is deteriorated, Resulting in problems such as thinning of the polarizing plate and production problems. Further, the brittleness was insufficient, and cracking occurred when bonding with the polarizer.

On the other hand, as the adhesive, there has been disclosed a technique of using an active energy ray-curable adhesive in addition to the above water-soluble resin (for example, see Patent Documents 2 to 4), and the adhesive is considered to be useful for bonding an acrylic resin film to a polarizer . However, the polarizing plate in which the acrylic resin film is bonded to the polarizer using an active energy radiation curable adhesive is still not sufficient as an adhesive force, and film peeling is likely to occur.

As described above, various kinds of resin films have been used for the polarizer protective film in accordance with the required quality such as the polarizer protective function and the retardation function. Since the film and the adhesive to be used have mutuality, for example, In the process of producing polarizing plates, it is necessary to prepare a bonding apparatus or equipment for corresponding to each of the water-soluble resin and the active energy ray-curable adhesive, resulting in complicated production.

Therefore, it is possible to suppress the occurrence of display unevenness (bend unevenness) of the liquid crystal display device with high water resistance, and also to have good adhesion with the polarizer by combination with water and active energy ray curable adhesive, A polarizing plate protective film is required.

Japanese Patent Laid-Open Publication No. 180422/2004 Japanese Patent Application Laid-Open No. 2010-230806 Japanese Patent Application Laid-Open No. 2010-077199 Japanese Patent Application Laid-Open No. 2011-123169

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems and circumstances. It is an object of the present invention to provide a liquid crystal display device which has a high water resistance, suppresses occurrence of display unevenness (bend unevenness) A polarizing plate protective film having good adhesion with a polarizer, a production method thereof, a polarizing plate provided with the polarizing plate protective film, and a liquid crystal display device.

In order to solve the above-described problems, the present inventors have found that, in the process of examining the cause of the above problems, the present inventors have found that a copolymer obtained by polymerizing an aromatic vinyl monomer and an unsaturated nitrile monomer as a main component of a thermoplastic resin, Of a polarizing plate protective film having a high water resistance and heat resistance and a polarizing plate protective film having an excellent adhesive property to a polarizer can be obtained by a combination of a water-soluble polymer and an active energy ray-curable adhesive And reached the present invention.

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

1. A thermoplastic resin composition comprising a copolymer (A) obtained by polymerizing an aromatic vinyl monomer and an unsaturated nitrile monomer and a copolymer (B) having an imide ring structure in a mass ratio of 100: 0 to 50: Lt; RTI ID = 0.0 > 50. ≪ / RTI >

2. The copolymer (A) obtained by polymerizing the aromatic vinyl monomer and the unsaturated nitrile monomer, wherein the aromatic vinyl monomer unit is contained in an amount of 50 to 75 mass% and the unsaturated nitrile monomer unit is contained in a ratio of 25 to 50 mass% The polarizing plate protective film according to claim 1,

3. The polarizing plate protective film according to claim 1 or 2, wherein the aromatic vinyl monomer is styrene and the unsaturated nitrile monomer is acrylonitrile.

4. The polarizer protective film according to any one of claims 1 to 3, wherein the imide ring structure is a maleimide structure or a glutarimide structure.

(5) A process for producing a copolymer (A), which comprises reacting at least one of an acid, an alcohol, a metal salt, a nonionic surfactant or a non-reactive quaternary ammonium salt type surfactant having a linear or branched alkyl group having from 8 to 22 carbon atoms, And 0.1 to 1.0% by mass based on the total mass of the polarizing plate protective film (B).

6. The polarizing plate according to any one of claims 1 to 5, further comprising at least one of core-shell type acrylic fine particles, styrene-conjugated dienic compound or butyl acrylate compound Protective film.

7. The aromatic vinyl monomer composition according to any one of claims 1 to 6, wherein the aromatic vinyl monomer and the unreacted monomer of the unsaturated nitrile monomer contained in the copolymer (A) are each 0.1 mass% or less with respect to the total mass of the copolymer (A) Wherein the polarizer protective film is a polarizer protective film.

8. The polarizer protective film according to any one of claims 1 to 7, wherein the haze is 1.0% or less and the yellow index (YI) is 1.0 or less.

9. The polarizing plate protective film according to any one of claims 1 to 8, which can be bonded to the polyvinyl alcohol polarizer using any of a polyvinyl alcohol adhesive or an active energy ray curable adhesive .

10. A process for producing a polarizing plate protective film for producing the polarizing plate protective film according to any one of claims 1 to 9, wherein the polarizing plate protective film is produced by a solution casting method Way.

11. A polarizing plate characterized in that the polarizing plate protective film according to any one of claims 1 to 9 and a polarizer are bonded by using a polyvinyl alcohol-based adhesive.

12. A polarizing plate characterized in that the polarizing plate protective film according to any one of claims 1 to 9 and a polarizer are bonded using an active energy ray curable adhesive.

13. The polarizing plate according to claim 11 or 12, wherein the polarizing plate protective film on the opposite side between the polarizing plate protective film and the polarizer according to any one of claims 1 to 9 is a cellulose ester film.

14. The polarizing plate according to any one of claims 11 to 13, characterized in that the adhesive on both sides of the polarizer is the same kind of adhesive.

15. The liquid crystal display device according to any one of claims 1 to 9, wherein the polarizing plate protective film is disposed on the visual side of the viewer-side polarizing plate and the backlight side of the backlight-side polarizing plate.

By the above-mentioned means of the present invention, it is possible to suppress the occurrence of uneven display (bend unevenness) of the liquid crystal display device with high water resistance and heat resistance, and to prevent the occurrence of display unevenness A polarizing plate protective film having good adhesion, a production method thereof, a polarizing plate provided with the polarizing plate protective film, and a liquid crystal display device can be provided.

The mechanism and mechanism for manifesting the effects of the present invention are not clarified, but are estimated as follows.

The reason why the polarizing plate protective film of the present invention exhibits excellent adhesion to the polyvinyl alcohol polarizer with either the polyvinyl alcohol adhesive or the active energy ray curable adhesive is that the copolymer (A) The imide ring constituting the acrylonitrile monomer or the copolymer (B) has a high polarity because it has a CN group, and therefore it is presumed that the adhesiveness is good due to the interaction with a water-borne having a hydrophilic group.

Further, since the copolymer (A) has an aromatic vinyl monomer such as styrene, the tertiary carbon generates radicals by corona treatment or plasma treatment, so that the adhesiveness with the active energy ray curable adhesive becomes good .

Further, regarding the display unevenness (bend unevenness) of the liquid crystal display device, since the aromatic vinyl monomers such as styrene constituting the copolymer (A) are hydrophobic, the water resistance is improved and the film dimensions due to omission of moisture from the film It is presumed that the bending of the panel is hardly caused, thereby improving the display unevenness (bend unevenness).

1 is a schematic view showing an example of a solution casting film forming process flow applicable to the production of the polarizing plate protective film of the present invention.
2 is a schematic diagram showing an example of the configuration of the polarizing plate of the present invention.
3 is a cross-sectional view showing an example of the configuration of the liquid crystal display device of the present invention.

The polarizing plate protective film of the present invention comprises a copolymer (A) obtained by polymerizing an aromatic vinyl monomer and an unsaturated nitrile monomer as main components of a thermoplastic resin and a copolymer (B) having an imide ring structure in a mass ratio of A: B = Is in the range of 100: 0 to 50:50. This feature is a technical feature that is common to the invention according to claims 1 to 15.

As an embodiment of the present invention, it is preferable that the copolymer (A) obtained by polymerizing the aromatic vinyl monomer and the unsaturated nitrile monomer in the range of 50 to 75 mol% and the unsaturated It is preferable that the composition contains nitrile monomer units in a proportion within a range of 25 to 50 mol% from the viewpoint of imparting good adhesiveness to a polarizer by using either a water-soluble resin or an active energy ray-curable adhesive, .

It is also preferable that the aromatic vinyl monomer is styrene and the unsaturated nitrile monomer is acrylonitrile because compatibility with a compound having an imide ring structure in addition to the effect of the present invention can be obtained.

In addition, when the imide ring structure is a maleimide structure or a glutarimide structure, the heat resistance is improved by increasing the Tg of the copolymer, thereby suppressing the warping of the panel due to heat and further improving the display unevenness (bend unevenness) .

Further, in order to easily peel off the dope from the metal support when forming the polarizing plate protective film, and to suppress the rise of the haze and the occurrence of the crossing, an acid, alcohol or metal salt having a linear or branched alkyl group having 8 to 22 carbon atoms , At least one of a nonionic surfactant and a non-reactive quaternary ammonium salt type surfactant is contained in an amount of 0.1 to 1.0 mass% with respect to the total mass of the copolymers (A) and (B).

Further, it is preferable to use a core / shell type acrylic fine particle, a styrene-conjugated diene compound or a butyl acrylate compound in order to obtain a film having excellent toughness.

The aromatic vinyl monomer and the unreacted monomer of the unsaturated nitrile monomer contained in the copolymer (A) are each 0.1 mass% or less based on the total mass of the copolymer (A) From the viewpoint of preventing deterioration in toughness of the film.

The polarizing plate protective film of the present invention has a haze of 1.0% or less and a yellow index (YI) of 1.0 or less, which is a preferable characteristic for use in optical films requiring transparency.

In addition, the polarizing plate protective film of the present invention can be bonded to a polyvinyl alcohol polarizer using either a polyvinyl alcohol-based adhesive or an active energy ray-curable adhesive, thereby simplifying the polarizing plate manufacturing process and improving productivity .

The production method of the polarizing plate protective film of the present invention is a preferable production method in which production by the solution softening method is capable of reducing the haze and yellow index (YI) and imparting good physical and optical properties to optical film applications .

From the viewpoint that the polarizing plate protective film on the opposite side of the polarizing plate protective film and polarizer of the present invention is a cellulose ester film, it is possible to provide a polarizing plate having excellent optical properties such as handleability, reworkability and visibility, It is a preferred form.

In addition, it is preferable that the adhesive on both sides of the polarizer is the same kind of adhesive, because the joining process is simplified and the advantage is obtained in terms of cost.

The polarizing plate protective film of the present invention is preferably arranged on the viewer side of the viewing side polarizing plate and the backlight side of the backlight side polarizing plate of the liquid crystal display device in view of suppressing display unevenness (bend unevenness) of the liquid crystal display device due to high water resistance and heat resistance Lt; / RTI >

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In the present application, " to " is used to mean that the numerical values described before and after the lower limit and the upper limit are included.

≪ Outline of polarizing plate protective film of the present invention &

The polarizing plate protective film of the present invention comprises a copolymer (A) obtained by polymerizing an aromatic vinyl monomer and an unsaturated nitrile monomer as a main component of a thermoplastic resin and a copolymer (B) having an imide ring structure in a mass ratio of A: B = 100: 0 to 50:50. By such a constitution, it is possible to suppress the occurrence of display unevenness (or bend unevenness) of liquid crystal display devices with high water resistance and heat resistance, And the active energy ray-curable adhesive, a polarizing plate protective film having good adhesiveness to the polarizer can be obtained.

It is necessary for the polarizing plate protective film of the present invention to contain the copolymer (A) and the copolymer (B) as a main component of the thermoplastic resin used for the film to achieve the object of the present invention. Refers to the total amount of the copolymer (A) and the copolymer (B) in an amount of at least 60 mass% of the thermoplastic resin constituting the polarizing plate protective film, preferably at least 80 mass% Preferably 90 mass% or more, and particularly preferably 95 mass% or more.

Further, it is preferable that the method for producing a polarizing plate protective film of the present invention is produced by a solution casting method because it can reduce haze and coloring (yellow index; YI).

The polarizing plate protective film of the present invention is preferably arranged on the viewer side of the viewing side polarizing plate and the backlight side of the backlight side polarizing plate of the liquid crystal display device to impart high water resistance and heat resistance to the polarizing plate and suppress occurrence of bend unevenness of the liquid crystal display . In addition, it is preferable to use a cellulose ester film as a retardation film on the cell side of the liquid crystal display device from the viewpoints of handleability, reworkability, and optical characteristics. Therefore, the polarizing plate of the present invention is a constitution in which the polarizer is sandwiched between the polarizing plate protective film of the present invention and the cellulose ester type retardation film, the bend unevenness can be suppressed and excellent visibility can be imparted to the liquid crystal display device, to be.

Since the polarizing plate protective film of the present invention has good adhesion with the polarizer even when used in combination with either a water-soluble resin or an active energy ray-curable adhesive, the polarizing plate protective film of either the water- An adhesive or a bonding apparatus can be prepared, so that the bonding process is not complicated and the cost is also advantageous.

≪ Configuration of polarizing plate protective film of the present invention &

<Copolymer>

The polarizing plate protective film of the present invention comprises a copolymer (A) obtained by polymerizing an aromatic vinyl monomer and an unsaturated nitrile monomer as a main component of a thermoplastic resin and a copolymer (B) having an imide ring structure in a mass ratio of A: B = 100: 0 to 50:50.

The monomer constituting the copolymer is referred to as &quot; unit &quot;.

&Lt; Copolymer (A) obtained by polymerizing an aromatic vinyl monomer and an unsaturated nitrile monomer >

[Aromatic vinyl monomer; Component (a)]

The aromatic vinyl monomer has a function of improving the water resistance of the copolymer (A). The aromatic vinyl monomer is preferably a styrene compound. Specific examples of the styrene compound include styrene; alkyl-substituted styrenes such as? -methylstyrene,? -methylstyrene and p-methylstyrene; Halogen-substituted styrenes such as 4-chlorostyrene and 4-bromostyrene; hydroxystyrenes such as p-hydroxystyrene,? -methyl-p-hydroxystyrene, 2-methyl-4-hydroxystyrene and 3,4-dihydroxystyrene; Vinylbenzyl alcohols; alkoxy-substituted styrenes such as p-methoxystyrene, p-tert-butoxystyrene and m-tert-butoxystyrene; Vinylbenzoic acids such as 3-vinylbenzoic acid and 4-vinylbenzoic acid; 4-vinylbenzyl acetate; 4-acetoxystyrene; Amide styrenes such as 2-butyl amide styrene, 4-methyl amide styrene and p-sulfonamide styrene; Aminostyrenes such as 3-aminostyrene, 4-aminostyrene, 2-isopropenyl aniline and vinyl benzyl dimethyl amine; Nitrostyrenes such as 3-nitrostyrene and 4-nitrostyrene; Cyanostyrenes such as 3-cyanostyrene and 4-cyanostyrene; Vinylphenylacetonitrile; Aryl styrenes such as phenylstyrene, and indenes.

Of these, styrene and? -Methylstyrene are preferable, and styrene is particularly preferable in terms of compatibility with other styrenic resins and (meth) acrylic resins. These aromatic vinyl monomers may be used singly or two or more of them may be used in combination.

[Unsaturated nitrile monomer; Component (b)]

Specific examples of the unsaturated nitrile monomer include vinyl cyanide compounds such as acrylonitrile, methacrylonitrile, ethacrylonitrile, and fumaronitrile, and among them, acrylonitrile is preferable. The acrylonitrile monomer has a high polarity because it has a CN group, and thus has good adhesiveness by interaction with a water-repellent having a hydrophilic group.

The unsaturated nitrile monomer may be used singly or in combination of two or more.

[Other monomers; Component (c)]

Further, the copolymer (A) according to the present invention may contain other monomer copolymerizable with the component (a) and / or the component (b). Examples of the copolymerizable monomer (c) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2- Alkyl (meth) acrylates such as methacrylate; (Meth) acrylic acid such as acrylic acid and methacrylic acid; ?,? - unsaturated carboxylic acids such as maleic anhydride; Maleimides such as N-phenylmaleimide, N-methylmaleimide and N-cyclohexylmaleimide; And glycidyl group-containing monomers such as glycidyl methacrylate. Of these, alkyl (meth) acrylates such as methyl acrylate are preferred. The other monomer (c) may be used alone or in combination of two or more.

[Percent monomer unit constituting the copolymer (A)]

The copolymer (A) according to the present invention is obtained by copolymerizing an aromatic vinyl monomer unit in an amount of 50 to 75 mol% and an unsaturated nitrile monomer unit in a ratio of 25 to 50 mol% (B) having an imidazole ring structure in view of compatibility with the copolymer (B). When other monomer units are used, they are preferably copolymerized at a ratio within a range of 0 to 25 mass%.

More preferably, the aromatic vinyl monomer unit is used in the range of 65 to 75 mol%, the unsaturated nitrile monomer unit is in the range of 25 to 35 mol%, and the other monomer units are used in the range of 0 to 25 mol% .

When the content of the aromatic vinyl monomer unit is in the range of 50 to 75 mol%, a high water resistance can be imparted to the polarizing plate protective film, and if the unsaturated nitrile monomer unit is within the range of 25 to 50 mol% Is excellent.

[Synthesis of Copolymer (A)]

As a method for obtaining the copolymer according to the present invention, for example, a monomer, an initiator, a solvent and the like are continuously fed into a complete stirring mixing tank and continuously withdrawn from the reaction tank to remove volatile components from the degassing system And removing it. It is preferable that the polymer stagnation in the degassing system is minimized.

For example, while styrene-acrylonitrile copolymers are generally produced by emulsion polymerization, suspension polymerization and bulk polymerization, a method of narrowing the composition distribution is to use a fully mixed type reactor in bulk polymerization A manufacturing method to be used, and the like.

As the polymerization initiator, conventional peroxide-based and azo-based ones can be used, and also redox-based ones can be used. The polymerization temperature may be in the range of 30 to 100 占 폚 in suspension or emulsion polymerization and in the temperature range of 80 to 160 占 폚 in mass or solution polymerization. In order to control the reduced viscosity of the obtained copolymer, polymerization may also be carried out using alkylmercaptan or the like as a chain transfer agent.

For example, it is preferable that the polymerization is carried out in a fully mixed type reactor and in a full liquid state in which the base layer portion is not present, and the unreacted monomer after polymerization is rapidly removed. The removal of unreacted monomers can be performed in a single-stage or multi-stage decompression apparatus or the like.

In the present invention, it is preferable that the unreacted monomer of the aromatic vinyl monomer and the unsaturated nitrile monomer contained in the copolymer (A) is 0.1% by mass or less based on the total mass of the copolymer (A) From the viewpoint of prevention of deterioration of film toughness and prevention of deterioration of toughness of the film.

Although the value of the unreacted monomer ratio varies depending on the constitution ratio of the copolymer (A), for example, the unreacted unsaturated nitrile monomer unit is preferably in the range of 0.001 to 0.005%, and the unreacted aromatic vinyl monomer unit If it is within the range of 0.05 to 0.1%, the above effect can be exhibited, which is preferable.

The control of the content of unreacted monomers can be carried out by controlling the polymerization temperature or the polymerization time in the polymerization reactor, the heating temperature in the heater, the melting temperature in the devolatilizing extruder, the amount of volatiles discharged from the vent of the devolatilizing extruder . In order to reduce the content of the unreacted monomer, for example, it is preferable to increase the polymerization time in the polymerization reactor or to increase the amount of discharged volatile components from the vent of the devolatilizing extruder.

The content of the unreacted monomer is adjusted by the polymerization temperature or the polymerization time in the polymerization reactor, the heating temperature in the heater, the melting temperature in the devolatilizing extruder, the displacement amount of volatile components (including unreacted monomers) from the vent of the devolatilizing extruder . In order to reduce the content of unreacted monomers, for example, the polymerization time in the polymerization reactor may be lengthened or the amount of volatile components discharged from the vent of the devolatilizing extruder may be increased.

Unreacted monomers can be measured by the following methods.

<Measurement method of unreacted monomers>

The content of the unreacted monomers contained in the copolymer according to the present invention can be measured by the following method.

1) Copolymer (0.1 g) is dissolved in 2 ml of acetone and subjected to ultrasonic treatment for 30 minutes. To this solution, 50 ppm of ethylene glycol monomethyl ether as an internal standard component is added, and then hexane is made up to 10 ml to obtain a sample solution.

2) The content (mass%) of unreacted monomers relative to the total mass of the copolymer contained in the sample solution is measured by GC / MS. The GC / MS measurement apparatus and measurement conditions are as follows.

Device: HP 6890GC / HP5973MSD (manufactured by Hewlett-Packard Company)

Column: DB-624 (0.25 mm id. X 30 ml) manufactured by J &

Oven program: 40 캜 (3 min) -20 캜 / min-230 캜 (8 min)

Inj: 160 ° C

AUX: 250 ° C

The weight average molecular weight (Mw) of the copolymer according to the present invention is preferably in the range of 1,000 to 2,000,000, more preferably in the range of 5,000 to 1,000,000, and more preferably in the range of 10,000 to 500,000 Particularly preferably within the range of 50,000 to 500,000.

The weight average molecular weight is measured by gel permeation chromatography (HLC8220GPC manufactured by Tosoh Corporation), and a column (TSK-GEL G6000HXL-G5000HXL-G5000HXL-G4000HXL-G3000HXL series manufactured by Tosoh Corporation). 20 mg ± 0.5 mg of the sample was dissolved in 10 ml of tetrahydrofuran, and the solution was filtered through a 0.45 mm filter. 100 ml of this solution is injected at a column temperature of 40 占 폚, and the value measured at a detector RI temperature of 40 占 폚 and converted to styrene is used.

&Lt; Copolymer (B) having an imide ring structure >

The polarizing plate protective film of the present invention contains a copolymer (B) having an imide ring structure in its structure together with the copolymer (A) from the viewpoint of improving the heat resistance of the film.

The copolymer (B) having an imide ring structure is preferably an acrylic resin having an imide ring structure in the structure.

As the acrylic resin having an imide structure, there can be mentioned acrylic resins having an imide ring structure (for example, a methacrylic acid ester, a methacrylic acid ester and a methacrylic acid ester), which are described in, for example, Japanese Patent Application Laid-Open Nos. 2009-270021, 2010-117451 and 2013-109285 ) Acrylic resin.

In the present invention, as the (meth) acrylic resin having an imide ring structure, an acrylic resin having a maleimide structure represented by the following formula (1) or a glutarimide structure represented by the following formula (2) is preferable.

[Chemical Formula 1]

R ¹ and R ² in the above formula (1) are independently of each other a hydrogen atom or a methyl group. R ³ represents a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, a cyclopentyl group, a cyclohexyl group, a benzyl group, a phenyl group, a methoxyphenyl group, a trichlorophenyl group, an ethylphenyl group, a tolyl group, a naphthyl group, A decyl group, a furfuryl group, and a thienyl group.

The ring structure represented by the formula (1) has an N-substituted maleimide structure. The N-substituted maleimide structure can be formed, for example, by polymerizing N-substituted maleimide such as phenyl maleimide and (meth) acrylic acid ester.

Specific examples of the monomer include N-phenylmaleimide, N-benzylmaleimide, N- (2-chlorophenyl) maleimide, N- (4- chlorophenyl) maleimide, N- Maleimide, N- (2-methylphenyl) maleimide, N- (2-methylphenyl) maleimide, N- (2,4,6-tribromophenyl) maleimide, N-naphthylmaleimide, N-anthraquinone, N- Methyl-1-phenyl-1H-pyrrole-2,5-dione, 3,4-dimethyl-1-phenyl-1H-pyrrole-2,5-dione, 1,3- Pyrrole-2,5-dione, 1,3,4-triphenyl-1H-pyrrole-2,5-dione, and the like. Among these monomers, N-phenylmaleimide, N-benzylmaleimide, N-cyclohexylmaleimide and N-methylmaleimide are preferable because of excellent heat resistance of acrylic resin. These second monomers may be used singly or in combination of two or more kinds.

Examples of the (meth) acrylic esters include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, methacryl T-butyl acrylate, 2-ethylhexyl methacrylate; Acrylonitrile, cyclopentyl methacrylate, cyclohexyl methacrylate, cyclooctyl methacrylate, tricyclodecyl methacrylate, bicyclooctyl methacrylate, tricyclododecyl methacrylate, isobornyl methacrylate, phenyl methacrylate , Benzyl methacrylate, 1-phenylethyl methacrylate, 2-phenoxyethyl methacrylate, 3-phenylpropyl methacrylate, 2,4,6-tribromophenyl methacrylate and the like. These monomers may be used singly or in combination of two or more. Of the methacrylic acid esters, methyl methacrylate is preferable because the obtained acrylic resin is excellent in transparency and weather resistance.

It is also preferable that the acrylic resin is made into a copolymer by further using another monomer. Examples of the other monomer include styrene, vinyltoluene,? -Methylstyrene,? -Hydroxymethylstyrene,? -Hydroxyethylstyrene, Allyl such as chlorostyrene, acrylonitrile, methacrylonitrile, methylvinyl ketone, ethylene, propylene, 4-methyl-1-pentene, vinyl acetate, methallyl alcohol, allyl alcohol and 2-hydroxymethyl- 2- (hydroxyalkyl) acrylic acid esters such as (meth) acrylic acid, 2- (hydroxymethyl) acrylate and ethyl 2- (hydroxymethyl) acrylate such as alcohol, acrylic acid, methacrylic acid and crotonic acid, 2- (Hydroxyalkyl) acrylic acid such as (hydroxyethyl) acrylic acid, N-vinylpyrrolidone, N-vinylcarbazole and the like. Of these, styrene,? -Methylstyrene, acrylonitrile, methacrylonitrile and the like are preferable, and styrene is more preferable. These other units may be copolymerized directly in the maleimide acrylic resin, or graft copolymerized.

The acrylic resin having a maleimide ring structure can be produced, for example, by the method described in JP-A-57-153008 and JP-A-2007-31537.

In the present invention, it is also preferable to use a copolymer of the monomer having the N-substituted maleimide structure and the other monomer. For example, in order to improve the adhesiveness with a water-repellent agent, acrylonitrile and methacrylate It is preferable to use a copolymer with an aromatic vinyl unit such as styrene or? -Methylstyrene from the viewpoint of adhesion to a nitrile-based unit such as acrylonitrile, or an adhesive with an active energy ray-curable adhesive, and specific examples include N-phenyl Maleimide-styrene copolymers, N-phenylmaleimide-styrene-acrylonitrile copolymers, and the like.

(2)

R ⁴ and R ⁵ in the formula (2) are independently of each other a hydrogen atom or a methyl group, and R ⁶ is a hydrogen atom, a straight chain alkyl group having 1 to 6 carbon atoms, a cyclopentyl group, a cyclohexyl group, to be.

The ring structure represented by the formula (2) is a glutarimide structure, and the glutarimide structure can be formed, for example, by imidizing a (meth) acrylic acid ester polymer with an imidizing agent such as methylamine.

The acrylic resin having a glutarimide ring structure preferably contains an aromatic vinyl unit such as styrene and? -Methylstyrene from the viewpoint of obtaining the effect of the present invention, and in order to improve the adhesion, And nitrile-based units such as nitrile and methacrylonitrile.

These other units may be copolymerized directly in the glutarimide resin, or graft copolymerized.

The (meth) acrylic resin having a cyclic structure of a glutarimide structure can be produced, for example, by the method described in International Publication No. 2007/26659, International Publication No. 2005/108438.

The content ratio of the imide ring structure of the acrylic resin having an imide ring structure is preferably within a range of 5 to 90 mass%, and more preferably within a range of 10 to 70 mass%. When the content of the imide ring structure in the structure of the acrylic resin having an imide ring structure is 5 mass% or more, sufficient heat resistance, solvent resistance, and surface hardness can be obtained. When the content ratio of the imide ring structure of the acrylic resin having an imide ring structure is 90 mass% or less, transparency and good film formability can be obtained.

The acrylic resin having an imide ring structure has a weight average molecular weight of preferably within the range of 1,000 to 2,000,000, more preferably within the range of 5,000 to 1,000,000, more preferably within the range of 10,000 to 500,000, Is in the range of 50,000 to 500,000. When the weight average molecular weight is within the above range, it is preferable from the viewpoint of moldability. The weight average molecular weight can be determined by gel permeation chromatography (GPC system, manufactured by Tosoh Corporation) using tetrahydrofuran as a solvent and by polystyrene conversion.

The acrylic resin having an imide structure preferably has a Tg (glass transition temperature) of preferably 115 占 폚 or higher, more preferably 125 占 폚 or higher, further preferably 130 占 폚 or higher, particularly preferably 135 占 폚 or higher, Gt; 140 C &lt; / RTI &gt; Setting the Tg within the above range is preferable from the viewpoint of obtaining a polarizing plate having small dimensional changes and small optical property changes even under a high temperature environment. The upper limit value of the Tg of the acrylic resin having an imide ring structure is not particularly limited, but is preferably 170 占 폚 or less from the viewpoint of moldability and the like.

<Other Resins>

The copolymers (A) and (B) according to the present invention can be used in combination with other resins within a range not to impair the effects of the present invention. As the other resin, other styrenic resin or (meth) acrylic resin can be preferably used.

The other styrene type resin may be a copolymer of a styrene type monomer and an unsaturated carboxylic acid monomer and / or an unsaturated dicarboxylic acid anhydride monomer with other monomer components. Examples of other copolymerizable monomers include alkyl methacrylates such as methyl methacrylate, cyclohexyl methacrylate, methylphenyl methacrylate and isopropyl methacrylate, and alkyl methacrylates such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl Unsaturated carboxylic acid alkyl ester monomers such as alkyl acrylates such as acrylate and cyclohexyl acrylate; Maleimide monomers such as N-phenylmaleimide and N-cyclohexylmaleimide; 1,3-butadiene, 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl- And two or more kinds of these may be copolymerized.

The (meth) acrylic resin includes a structural unit derived from a (meth) acrylate. Examples of (meth) acrylic esters include acrylic acid alkyl esters having 4 to 18 carbon atoms such as methyl acrylate, ethyl acrylate and butyl acrylate; And methacrylic acid alkyl esters having 5 to 18 carbon atoms such as methyl methacrylate, ethyl methacrylate and butyl methacrylate. Of these, methyl methacrylate is preferable in terms of easy polymerization and the like. The other monomers may be used singly or in combination of two or more kinds.

The (meth) acrylic resin may further contain a structural unit derived from another monomer, if necessary. Examples of other monomers include?,? - unsaturated acids such as acrylic acid and methacrylic acid; Cyclic acid anhydride monomers such as maleic anhydride, itaconic anhydride, glutaric anhydride, citraconic anhydride, and aconitic anhydride; Vinyl esters such as vinyl acetate and vinyl benzoate; Vinyl ether compounds such as methyl vinyl ether, ethyl vinyl ether and propyl vinyl ether; And the like. The other monomers may be used singly or in combination of two or more kinds.

The weight average molecular weight of the resin is preferably within a range of 100,000 or more, preferably 150,000 or more, more preferably 200,000 to 1,500,000 in order to further improve the brittleness of the resulting film. The weight average molecular weight (Mw) of the resin is measured in the same manner as described above.

&Lt; Mixing Ratio of Copolymer and Copolymer (B) >

The polarizing plate protective film of the present invention comprises a copolymer (A) obtained by polymerizing an aromatic vinyl monomer and an unsaturated nitrile monomer and a copolymer (B) having an imide ring structure in a mass ratio of 100: 0 to 50: (Bend unevenness) of the liquid crystal display device is suppressed, and the water-soluble and active energy ray-curable adhesive is contained in the range of 50 to 50% A polarizing plate protective film having good adhesion with a polarizer can be obtained.

If the content by mass of the copolymer (A) is less than 50, the water resistance, heat resistance and toughness deteriorate. Therefore, in manifesting the effects of the present invention, the content of the copolymer (A) should be within the above range.

Preferably, A: B is in the range of 90:10 to 55:45, and more preferably in the range of 80:20 to 60:40.

<Additives>

The polarizing plate protective film of the present invention may further contain various additives such as a release auxiliary, an antistatic agent, an antioxidant, an ultraviolet absorber, a fine particle (matting agent) for imparting slidability and an impact reinforcement for increasing toughness have.

(Peeling aid, antistatic agent)

The film-like material comprising a copolymer of an aromatic vinyl monomer and an unsaturated nitrile monomer according to the present invention has a high adhesion with a metal support, so that it can be easily peeled from a metal support and the elongation at peeling can be suppressed. It is preferable to include a release auxiliary or an antistatic agent.

The release auxiliary is preferably at least one selected from the group consisting of an acid having a linear or branched alkyl group of 8 to 22 carbon atoms, an alcohol, a metal salt, a nonionic surfactant or a non-reactive quaternary ammonium salt type surfactant, In the range of 0.1 to 1.0 mass% with respect to the total mass of the components (A) and (B).

Examples of the compound include an alkylsulfonate and an alkylbenzenesulfonate. Examples of the salt include sodium salt, potassium salt, amine salt, ammonium salt, and phosphonium salt.

Specific examples thereof include sodium decylsulfonate, sodium decylbenzenesulfonate, potassium decylbenzenesulfonate, sodium dodecylsulfonate, potassium dodecylsulfonate, sodium dodecylbenzenesulfonate, potassium dodecylbenzenesulfonate, dodecylbenzenesulfonate tetrabutylammonium, Sodium tetradecylbenzenesulfonate, potassium tetradecylbenzenesulfonate, sodium hexadecylsulfonate, sodium hexadecylbenzenesulfonate, potassium hexadecylbenzenesulfonate, and the like can be given.

Examples of commercially available products include Hostastat HS-1 manufactured by Clariant Japan KK, Elecut S-412-2, Elecut S-418 manufactured by Takemoto Oil Co., Ltd., Neopelex G65 manufactured by Kao Corporation .

Examples of the alcohols include octane-1-ol, nonane-1-ol, decane-1-ol, undecane-1-ol, dodecane-1-ol, tridecane- 1-ol, hexadecan-1-ol, heptadecan-1-ol, octadecan-1-ol, nonadecan- And docosanoic-1-ol, and octadecan-1-ol (stearyl alcohol) is preferable.

Further, it is also effective to use a nonionic surfactant as a release aid. Examples thereof include polyoxyalkylene glycols such as polyoxyethylene polyoxypropylene glycol and polyoxyalkylene styrenated phenyl Polyoxyethylene sorbitan monococoate, polyoxyethylene sorbitan monostearate, and polyoxyethylene hydrogenated castor oil, such as polyoxyethylene sorbitan monocoumarate, polyoxyethylene sorbitan monococoate, polyoxyethylene sorbitan monococoate, polyoxyethylene sorbitan monostearate and polyoxyethylene hydrogenated castor oil, And oxyalkylene fatty acid esters. These surfactants may be used alone or in combination of two or more. As these commercially available products, there can be mentioned, for example, ethers manufactured by Dai-ichi Kogyo Seiyaku Co.,

In addition, it is also preferable to use a non-reactive quaternary ammonium salt type surfactant as a release auxiliary, and among these, a non-reactive quaternary ammonium salt type surfactant having not more than two methyl groups is useful. The surfactant is not particularly limited, and examples of the non-reactive quaternary ammonium salt type surfactant having one methyl group include polyoxypropylene methyldiethylammonium chloride, methyldiethyl (2-methoxyethyl) ammonium chloride, Octyl bis polyoxyethylene methyl ammonium chloride, lauryl bis polyoxyethylene methyl ammonium chloride, oleyl bis polyoxyethylene methyl ammonium chloride, polyoxyethylene dodecyl monomethyl ammonium chloride, Examples of the reactive quaternary ammonium salt type surfactant include aliphatic alkyl quaternary ammonium salts such as octyldimethylethylammonium ethylsulfate, lauryldimethylethylammonium ethylsulfate, palmityldimethylethylammonium ethylsulfate, didecyldimethylammonium chloride , Distearyldimethylammonium chloride, lauryldime T-butylbenzylammonium chloride, stearyldimethylhydroxyethylammonium para-toluenesulfonate, alkylbenzyldimethylammonium chloride, ethyldimethyl (2-methoxyethyl) ammonium chloride and the like are suitably used. In particular, it is particularly preferred that the surfactant contains an alkylene oxide (AO) group. The alkylene oxide group may be contained in either or both of the anion component and the cation component of the surfactant. Examples of the alkylene oxide (AO) group include polyoxypropylene methyldiethylammonium chloride, methyldiethyl (2-methoxyethyl) ammonium chloride, octylbispolyoxyethylenemethylammonium chloride, laurylbis It is also a more preferable form to use polyoxyethylene methyl ammonium chloride, oleyl bis polyoxyethylene methyl ammonium chloride, polyoxyethylene dodecyl monomethyl ammonium chloride and ethyl dimethyl (2-methoxyethyl) ammonium chloride. These surfactants may be used singly or in combination of two or more kinds.

As the non-reactive quaternary ammonium salt type surfactants, commercially available products can be used. Examples thereof include trade names "ADEKARCOL CC-36" (number of methyl groups: 1, manufactured by ADEKA) Cation L-207 "(number of methyl groups: 1, manufactured by Nippon Express Co., Ltd.), trade name" CATHIOL L-207 " (Trade name, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), trade name "Catogens ES-O" (number of methyl groups: 2, number of methyl groups: 2, (Trade name: CATHIOGEN ES-WS-L-9 (number of methyl groups: 2, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) (Trade name, manufactured by Seiyaku Co., Ltd.), trade name "Catiogen ES-P" (number of methyl groups: 2, manufactured by Daiichi Kogyo Seiyaku Co., , Manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), trade name "Catiogen S" ( (Number of methyl groups: 2, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), trade name "Catiogen D2" (number of methyl groups: (Number of methyl groups: 2, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) may be used.

(Antioxidant)

In the present invention, a commonly known antioxidant may be used. In particular, compounds of the lactone system, sulfur system, phenol system, double bond system, hindered amine system and phosphorus system can be preferably used.

For example, "Irgafos XP40, Irgafos XP60" commercially available from BASF Japan Ltd. can be mentioned.

As the phenolic compound, those having a structure of 2,6-dialkylphenol are preferable, and examples thereof include &quot; Irganox 1076 &quot;, &quot; Irganox 1010 &quot;, available from BASF Japan Co., "ADEKA STAP AO-50" commercially available from ADEKA.

Examples of the phosphorus compound include "Sumilizer GP" commercially available from Sumitomo Chemical Co., Ltd., "ADK STAB PEP-24G", "ADK STAB PEP-36" commercially available from ADEKA And "ADK STAB 3010", "IRGAFOS P-EPQ" commercially available from BASF Japan Ltd., and "GSY-P101" commercially available from Sakaikogaku Kogyo Co., Ltd.

Examples of the hindered amine compound include "Tinuvin 144" and "Tinuvin 770" available from BASF Japan Co., Ltd., "ADK STAB (trade name)" available from ADEKA, LA-52 &quot;.

Examples of the sulfur-based compounds include "Sumilizer TPL-R" and "Sumilizer TP-D" commercially available from Sumitomo Chemical Co., Ltd.

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

(Ultraviolet absorber)

The polarizing plate protective film according to the present invention preferably contains an ultraviolet absorber. Examples of applicable ultraviolet absorbers include ultraviolet absorbers such as benzotriazole-based, 2-hydroxybenzophenone-based, salicylic acid phenyl ester-based and triazine- have. For example, there can be mentioned 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5- , Triazole compounds such as 2- (3,5-di-t-butyl-2-hydroxyphenyl) benzotriazole, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy- Phenone, and 2,2'-dihydroxy-4-methoxybenzophenone.

These ultraviolet absorbers may be commercially available products. For example, TINUVIN 109, TINUVIN 171, TINUVIN 234, TINUVIN 326, TINUVIN 327, TINUVIN 328, TINUVIN 928 (manufactured by BASF Japan) Or 2,2'-methylenebis [6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol] (molecular weight 659; As an example of a commercially available product, LA31 manufactured by Adeka Co., Ltd.) can be preferably used.

(Made by Matt)

In the present invention, it is preferable to add a matting agent in order to impart slipperiness to the polarizing plate protective film.

As the matting agent used in the present invention, either the inorganic compound or the organic compound may be used if the transparency of the obtained film is not deteriorated and the heat resistance in the film forming step is sufficient. These matting agents may be used alone or in combination of two or more.

By using particles having different particle sizes or shapes (for example, needle shape and spherical shape), it is possible to achieve both high transparency and slidability.

Of these, silicon dioxide is particularly preferably used from the viewpoint of excellent transparency (haze).

Specific examples of silicon dioxide include Aerosil 200V, Aerosil R972V, Aerosil R972, R974, R812, 200, 300, R202, OX50, TT600, NAX50 (manufactured by Nippon Aerosil Co., (Manufactured by Nippon Shokubai Co., Ltd.), Silo Fobik 100 (manufactured by Fuji Silicia), Nipil E220A (manufactured by Nippon Silica Kogyo Co., Ltd.), Admapine SO Tex), and the like can be preferably used.

As the shape of the matte-made particles, it is possible to use them without particular limitation, such as irregular shape, needle shape, flattened shape, spherical shape and the like, and spherical particles are particularly preferable because transparency of the resulting film can be improved.

When the particle diameter of the matte particle is close to the wavelength of visible light, the light is scattered and the transparency is lowered. Therefore, the particle size of the matte particle is preferably smaller than the wavelength of visible light and is preferably 1/2 or less of the wavelength of visible light. However, if the size of the matte-made particles is too small, the effect of improving the slipping property may not be exhibited. Therefore, it is particularly preferable that the particle size is within the range of 80 to 180 nm.

The particle size means the size of the aggregate when the particles are aggregates of primary particles. When the particle is not spherical, it means the diameter of the circle corresponding to the projected area.

(Impact stiffener)

The polarizing plate protective film according to the present invention preferably contains at least one of core-shell type acrylic fine particles, styrene-conjugated dienic compound or butyl acrylate compound as an impact reinforcing material in order to increase impact resistance.

In particular, a core / shell type graft copolymer in which a (meth) acrylic resin is grafted to a copolymer of a (meth) acrylic rubber and an aromatic vinyl compound disclosed in Japanese Patent Laid-Open Publication No. 2009-84574, Acrylic styrene-butadiene-based elastic fine particles described in Japanese Patent Laid-Open Publication No. 2013-83907, and the like.

For example, the core-shell type acrylic fine particles are obtained by polymerizing a mixture of 80 to 98.9 mass% of methyl methacrylate, 1 to 20 mass% of alkyl acrylate and 0.01 to 0.3 mass% of a multi-functional graft, and; A soft layer obtained by polymerizing a mixture of 75 to 98.5 mass% of an alkyl acrylate, 0.01 to 5 mass% of a polyfunctional crosslinking agent, and 0.5 to 5 mass% of a polyfunctional grafting agent; An extreme hard layer obtained by polymerizing a mixture of 80 to 99 mass% of methyl methacrylate and 1 to 20 mass% of alkyl acrylate.

The styrene-conjugated diene-based compound is preferably a styrene-butadiene-based copolymer. The copolymer may be a rubber-like elastic material or an elastic organic fine particle. Specifically, the elastic organic fine particles are preferably core-shell type particles. The core portion is composed of a soft polymer; It is preferable that the shell portion covering the periphery of the core portion is composed of the copolymer according to the present invention or another polymer having high compatibility with other resins.

The soft polymer includes a structural unit derived from a conjugated diene monomer and, if necessary, a structural unit derived from another monomer. Examples of the conjugated diene monomer include 1,3-butadiene (hereinafter may be simply referred to as "butadiene"), isoprene, 1,3-pentadiene, 2,3-dimethyl- 1,3-butadiene, myrcene and the like, preferably butadiene and isoprene. Examples of other monomers include styrene components such as styrene and? -Methylstyrene. The content of the structural unit derived from the conjugated diene monomer in the soft polymer is usually 50% by mass or more, preferably 70% by mass or more, and more preferably 90% by mass or more.

Examples of other polymers include copolymers of acrylonitrile and styrene, polymers containing methacrylic acid esters such as methyl methacrylate as a main component, and the like.

The volume average particle diameter of the elastic organic fine particles is preferably 0.35 占 퐉 or less, more preferably 0.01 to 0.35 占 퐉, and still more preferably 0.05 to 0.30 占 퐉. If the particle diameter is more than the predetermined value, sufficient shock absorbing property can be imparted to the film; If the particle diameter is less than a certain value, it is difficult to impair the transparency of the resulting film.

As commercial products, for example, Metablen C-140A, C-215A (manufactured by Mitsubishi Rayon Co., Ltd.), Toughprene 126, Asaflex 800, Asaflex 825 (manufactured by Asahi Kasei Chemicals Co., Ltd.) TR2000, and TR2250 (manufactured by JSR Corporation).

The other rubber-like elastomer is an acrylic ester-based rubber-like polymer, and a rubber-like polymer mainly composed of an acrylic ester-based polymer containing butyl acrylate as a main component is preferable.

The rubber-like elastomer using butyl acrylate may be an elastomer particle, or two kinds of polymers may be layered. As a representative example thereof, a hard resin layer comprising a copolymer of a grafted rubber elastic component of an alkyl acrylate such as butyl acrylate and styrene, and a copolymer of polymethyl methacrylate and / or methyl methacrylate and an alkyl acrylate, And elastomer particles forming a layer with a shell structure.

The content of the shock absorber is preferably 0.1 to 10% by mass, more preferably 1 to 5% by mass, based on the total amount of the copolymer and the other resin according to the present invention.

When the impact stiffener used in the present invention is an acrylic fine particle, it is preferable that the styrene-acrylonitrile-based copolymer used in the present invention has a refractive index equal to or less than ± 0.01, .

&Lt; Polarizing plate protective film production method &gt;

As the method for producing the polarizing plate protective film of the present invention, it is possible to use a production method such as a general inflation method, a T-die method, a calendar method, a cutting method, a soft method, an emulsion method and a hot press method. The solution casting method and the melt casting film forming method can be selected from the viewpoint of suppression of optical defects such as cracking, dying and the like. In particular, the solution casting method is a method of controlling the distribution state of the resin to suppress the panel bend In addition to the effect, it is preferable from the viewpoint of obtaining a uniform and smooth surface and also reducing the haze and the yellow index (YI).

&Lt; Solution &lt;

Hereinafter, a production example of producing the polarizing plate protective film of the present invention by the solution casting method will be described.

The polarizing plate protective film of the present invention can be produced by dissolving at least a compound such as a copolymer, a resin and an additive according to the present invention in a solvent to prepare a dope and filtering the dope, A step of forming a web by pliability on a support, a step of peeling the formed web from a metal support to form a film, a step of stretching and drying the film, and a step of winding the dried film into a roll form after cooling Loses.

Hereinafter, each step will be described.

(1) Dissolution Process

A step of dissolving the resin and, if necessary, other compounds in an organic solvent mainly containing a good solvent for the resin in a dissolving oven while stirring to form a dope; or a step of mixing and mixing the above- Thereby forming an impregnated dope.

When the polarizing plate protective film of the present invention is prepared by the solution casting method, the organic solvent useful for forming the dope can be used without limitation as long as it dissolves the resin and other compounds at the same time.

Examples of the chlorinated organic solvent include methylene chloride and examples of the non-chlorinated organic solvent include methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, , Ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3 , 3,3-hexafluoro-2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro Propanol, and nitroethane. As the main solvent, for example, methylene chloride, methyl acetate, ethyl acetate and acetone can be preferably used, and methylene chloride or ethyl acetate is particularly preferable.

The dope preferably contains, in addition to the organic solvent, a linear or branched aliphatic alcohol having 1 to 4 carbon atoms in the range of 1 to 40 mass%. When the proportion of alcohol in the dope is high, the web gels to facilitate peeling from the metal support. When the proportion of alcohol is small, it also has a role of promoting dissolution of resins and other compounds in the non-chlorinated organic solvent system. In the film formation of the polarizing plate protective film of the present invention, a film forming method using a dope in which the alcohol concentration is in the range of 0.5 to 15.0 mass% can be applied in order to enhance the planarity of the obtained polarizing plate protective film.

In particular, the dope composition is preferably a dope composition obtained by dissolving a resin and other compounds in a total amount of 15 to 45 mass% in a solvent containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 4 carbon atoms.

Examples of the straight chain or branched aliphatic alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol and tert-butanol. Of these, methanol and ethanol are preferable in that the dope has a relatively low stability, a relatively low boiling point, and good drying property.

The dissolution of the resin or other compound can be carried out at a normal pressure, a method in which the main solvent is boiling or lower, a method in which the solvent is pressurized at a boiling point or more of the main solvent, JP-A 9-95544, JP-A 9-95557 Various methods such as a method of performing a cooling dissolution method as disclosed in JP-A-9-95538 and a method of operating at a high pressure as disclosed in JP-A-11-21379 can be used. A method in which the solvent is pressurized at a boiling point or more of the main solvent is preferable.

The concentration of the resin in the dope is preferably in the range of 10 to 40 mass%. A compound is added to the dope during or after dissolution, dissolved and dispersed, filtered with a filter, defoamed, and sent to the next process with a liquid-feeding pump.

For the filtration of the dope, it is preferable to filter the dope with, for example, a filtration material having a 90% trapped particle diameter of 10 to 100 times the average particle diameter of the fine particles, preferably with a main filter 3 having a leaf disc filter Do.

In the present invention, it is preferable that the filtration material used for filtration has a small absolute filtration accuracy. However, if the absolute filtration precision is too small, clogging of the filtration material tends to occur easily and the replacement of the filter material must be frequently performed, There is a problem.

Therefore, in the present invention, the filter medium used in the dope preferably has an absolute filtration accuracy of 0.008 mm or less, more preferably 0.001 to 0.008 mm, and even more preferably 0.003 to 0.006 mm.

The material of the filter medium is not particularly limited and a usual filter medium can be used. However, a filter material made of plastic fibers such as polypropylene or Teflon (registered trademark), or a metal filter material made of stainless steel fiber or the like is preferable.

In the present invention, it is preferable that the flow rate of the dope at the time of filtration is 10 to 80 kg / (h · m ² ), preferably 20 to 60 kg / (h · m ² ). If the flow rate of the dope during filtration is 10 kg / (hm ² ) or more, efficient productivity is obtained. If the flow rate of the dope during filtration is within 80 kg / (hm ² ) So that the filter medium is not damaged.

The filtration pressure is preferably 3500 kPa or less, more preferably 3000 kPa or less, and further preferably 2500 kPa or less. The filtration pressure can be controlled by appropriately selecting the filtration flow rate and the filtration area.

1 is a schematic view showing an example of a solution casting film forming process flow applicable to the production of the polarizing plate protective film of the present invention.

The dope produced by the charging kiln 41 is removed by the filter 44 to remove large aggregates and is sent to the stock kiln 42. Thereafter, various additive liquids are added to the main dope melting furnace (1) from the stock kiln (42).

Thereafter, the main dope is filtered with a main filter 3, and a matting liquid dispersion, a liquid added with an ultraviolet absorber, and the like are added inline from the conduit 16 to the main filter.

In most cases, the main dope may contain about 10 to 50% by mass of recovered scrap.

The recovered scraps are obtained by finely pulverizing the polarizing plate protective film of the present invention. For example, the recovered scraps are obtained by cutting both side portions of the film, which are generated when the polarizing plate protective film is formed, A protective film fabric is used.

As the raw material of the resin used in the preparation of the dope, pellets of resins and other compounds may be preferably used.

(2) Flexible process

(2-1) Dope flexing

An endless metal supporting body 31 for feeding the dope to the pressurizing die 30 through a feed pump (for example, a pressurized metering gear pump) and infinitely feeding it, for example, a stainless steel belt or a rotating metal drum In a flexible position on a metal support of a press die slit.

The metal support in the casting step is preferably mirror-finished on the surface, and as the metal support, a stainless steel belt or a drum finished with plating on the cast iron surface is preferably used. The width of the cast may be in the range of 1 to 4 m, preferably in the range of 1.5 to 3 m, more preferably in the range of 2 to 2.8 m. The surface temperature of the metal support in the softening step is set to a temperature of -50 ° C to a temperature at which the solvent does not foam by boiling, more preferably -30 to 100 ° C. A higher temperature is preferable because the drying speed of the web can be made faster, but an excessively high temperature may cause the web to foam or deteriorate in planarity. A suitable support temperature is appropriately determined at 0 to 100 캜, more preferably in the range of 5 to 30 캜. Alternatively, it is preferable that the web be gelled by cooling to peel off the drum in a state containing a large amount of residual solvent. A method of controlling the temperature of the metal support is not particularly limited, but there is a method of blowing hot air or cold air, or a method of bringing hot water to the side of the metal support. The use of hot water is preferable because the time required for the temperature of the metal support to become constant is short since the heat transfer is performed more efficiently. In the case of using hot wind, in consideration of the temperature drop of the web due to the latent heat of evaporation of the solvent, the hot wind above the boiling point of the solvent may be used, while the foaming is also prevented while using wind at a temperature higher than the target temperature. Particularly, it is preferable to change the temperature of the support and the temperature of the drying wind during the period from the time of pouring to the time of peeling, thereby efficiently performing drying.

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 coated 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 and laminated.

(3) Solvent Evaporation Process

A web (a dope is formed on a flexible support and the formed dope is referred to as a web) is heated on a flexible support to evaporate the solvent.

In order to evaporate the solvent, there are a method of blowing air from the web side, 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, and the like. . 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 占 폚, it is preferable to apply warm air at this temperature to the upper surface of the web or 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 the range of 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 peeled web is sent to the next process as a film.

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

The amount of the 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, In case of peeling at a large number of points of view, if the web is too soft, the flatness is deteriorated in peeling, and the peeling tension and the streaks tend to occur, so that the amount of the residual solvent at the time of peeling is determined from the balance of economical speed and quality .

The amount of residual solvent in the web is defined by the following formula (Z).

The formula (Z)

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 115 캜 for one hour.

The peeling tension when peeling the film from the metal support is usually in the range of 196 to 245 N / m, and it is preferable to peel off with a tensile force of 190 N / m or less when wrinkles tend to occur at peeling.

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

(5) Drying and drawing process

The drying process may be divided into a preliminary drying process and a main drying process.

<Preliminary drying step>

The web obtained by peeling from the metal support is dried. The web may be dried while conveying the web by a plurality of rollers disposed on upper and lower sides, or both ends of the web may be fixed with a clip such as a tenter dryer and dried while being conveyed.

The means for drying the web is not particularly limited and can generally be carried out by hot air, infrared rays, heating rollers, microwaves or the like, but from the viewpoint of simplicity, it is preferable to conduct it by hot air.

The drying temperature in the drying step of the web is preferably -5 DEG C or lower of the glass transition point of the film, and it is effective to carry out the heat treatment within a range of 10 minutes to 60 minutes at a temperature of 100 DEG C or higher. The drying is carried out at a temperature in the range of 100 to 200 ° C, more preferably in the range of 110 to 160 ° C.

<Stretching Step>

The polarizing plate protective film of the present invention can control the orientation of molecules in the film by stretching treatment, and can improve planarity or toughness.

The polarizing plate protective film of the present invention is preferably stretched in the longitudinal direction (also referred to as the MD direction) and / or the transverse direction (also referred to as the TD direction) and is preferably stretched in the longitudinal direction or the transverse direction in the range of 1.01 to 10 times It is preferable to stretch it.

The stretching operation may be performed in multiple steps. In the case of biaxial stretching, simultaneous biaxial stretching may be performed, or may be performed stepwise. In this case, the stepwise means that, for example, the stretching in which the stretching direction is different can be performed sequentially, the stretching in the same direction can be divided into multiple steps, and the stretching in different directions can be added to any one of the steps.

That is, for example, the following stretching steps are 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 flexible direction Stretching in the flexible direction

The simultaneous biaxial stretching may include stretching in one direction and shrinking the other by relaxing the tension.

The amount of the residual solvent at the start of the stretching is preferably within a range of 2 to 10 mass%.

If the amount of the residual solvent is 2% by mass or more, the film thickness deviation becomes small and is preferable from the viewpoint of planarity, and if it is within 10% by mass, the unevenness of the surface is reduced and planarity is improved.

The polarizing plate protective film of the present invention preferably has a Tg of from (Tg + 15) to (Tg + 15) when the glass transition temperature of the film is taken as Tg in the MD direction and / or the TD direction, preferably the TD direction, (Tg + 50) &lt; 0 &gt; C. When stretched in the above temperature range, the stretching stress can be lowered and the haze is lowered. In addition, the occurrence of breakage can be suppressed, and a polarizing plate protective film excellent in planarity can be obtained. The stretching temperature is preferably in the range of (Tg + 20) to (Tg + 40) deg.

In the polarizing plate protective film of the present invention, it is preferable to stretch the web at least in the MD or TD direction within the range of 1.01 to 10 times. The stretching range is preferably 1.1 to 10 times the original width , And more preferably in the range of 1.2 to 8 times. Within the above range, the film becomes strong, and the film can be thinned, and the planarity of the film can be improved.

In order to stretch in the MD direction, the peel tension is desirably peeled to 130 N / m or more, and particularly preferably 150 to 170 N / m. Since the web after peeling is in a state of a high residual solvent, stretching in the MD direction can be performed by maintaining the same tensile force as the peeling tension. As the web dries and the amount of the residual solvent decreases, the elongation in the MD direction decreases.

Further, in the MD direction stretching, a roller stretcher using the peripheral speed difference of the roller can be used, and the stretching magnification can be calculated from the rotational speed of the belt support and the running speed of the roller stretcher.

In order to stretch in the TD direction, for example, a method of drying the entire drying step or a part of the steps as disclosed in Japanese Patent Application Laid-Open No. 62-46625 while keeping the both ends of the web width wide (Called a tenter system). Among them, a tenter system using a clip and a pin tenter system using a pin are preferably used.

In the stretching in the TD direction, stretching at a stretching speed of 250 to 500% / min in the film width direction is preferable from the viewpoint of improving the planarity of the film.

When the stretching speed is 250% / min or more, the flatness is improved and the film can be processed at a high speed. Therefore, it is preferable from the viewpoint of production suitability. If the stretching speed is 500% / min or less, desirable.

The preferred stretching speed is in the range of 300 to 400% / min. The stretching speed is defined by the following formula (E).

(E) elongation speed (% / min) = [(d ₁ / d ₂ ) -1] × 100 (%) / t

In (formula (E), d ₁ is the width of the stretching direction of the resin film after the stretching, d ₂ is the width of the stretching direction of the resin film before stretching, t is time (min required for stretching) being)

The in-plane retardation value Ro and the retardation value Rt in the thickness direction of the polarizing plate protective film of the present invention were measured using an automatic birefringence index liquid scan (Axo Scan Mueller Matrix Polarimeter: manufactured by Liquid Matrix Co., Ltd.) The three-dimensional refractive index is measured at a wavelength of 590 nm under an environment of 55% RH, and the refractive indices n _x , n _y , and n _z can be calculated.

The polarizing plate protective film of the present invention is characterized in that the retardation value Ro defined by the following formula (i) is in the range of 0 to 70 nm and the retardation value Rt defined by the following formula (ii) is -50 To 10 nm is particularly preferable in the case of being provided as a polarizing plate protective film which does not require retardation. The polarizing plate protective film may be stretched while adjusting the stretching magnification in at least the MD direction or the TD direction.

Formula (i): Ro = (n x -n y) × d (nm)

Formula (ii): Rt = {( n x + n y) / 2-n z} × d (nm)

[In the formulas (i) and (ii), n _x represents the refractive index in the direction x at which the refractive index becomes maximum in the in-plane direction of the film. n _y represents the refractive index in the direction y perpendicular to the direction x in the in-plane direction of the film. and n _z represents the refractive index in the thickness direction z of the film. d represents the thickness (nm) of the film]

<Knurling>

It is preferable to provide a slitter after the predetermined heat treatment or cooling treatment to cut the end portion before winding to obtain a good winding state. It is preferable to perform knurling on both ends of the width.

The knurling can be formed by pushing the heated embossing roller. The embossing rollers are formed with fine irregularities, and by pressing them, irregularities can be formed on the film, so that the ends can be bulged.

The height of the knurling at both ends of the width of the polarizing plate protective film of the present invention is preferably 4 to 20 占 퐉 and the width is 5 to 20 mm.

Further, in the present invention, it is preferable that the knurling is provided before winding and after drying in the film-forming step of the film.

(6) Coiling process

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

As the winding method, a generally used one may be used, and examples thereof include a constant 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.

<Melting and Foaming Method>

The polarizing plate protective film of the present invention may be formed by the melt-blowing method. The melt-blowing process refers to heating and melting a composition including a copolymer and other compounds according to the present invention to a temperature at which the fluidity is exhibited, and then, the melt of the fluidity is softened.

In the melt-extrusion method, a melt-extrusion method is preferable in terms of mechanical strength and surface precision. It is preferable that a plurality of raw materials used for melt extrusion are usually previously kneaded and pelletized.

The pelletization may be carried out by known methods. For example, a copolymer or other compound according to the present invention is fed to an extruder as a feeder, kneaded using a single- or twin-screw extruder, extruded from a die into a strand shape, Or by air cooling and cutting.

The additives may be mixed before being supplied to the extruder, or they may be supplied to individual feeders.

Small amounts of additives such as particles and antioxidants are preferably mixed in advance in order to mix them uniformly.

The extruder is preferably processed at a low temperature as low as possible so as to reduce the shearing force and to make the resin pellet so that the resin does not deteriorate (decrease in molecular weight, coloration, gel formation, etc.). For example, in the case of a twin-screw extruder, it is preferable to use a deep groove-type screw to rotate in the same direction. In terms of kneading uniformity, an engaging type is preferable.

Film formation is carried out using the pellets obtained as described above. Of course, it is also possible to feed the powder of the raw material directly to the extruder by using a feeder, without forming pellets, and to form the film as it is.

The above pellets are extruded by using a uniaxial or biaxial type extruder and the extruded product is filtered at a temperature of about 200 to 300 DEG C by using a filter such as a leaf disc type to remove foreign matter. The film is nipped with a cooling roller and an elastic touch roller, and is solidified on a cooling roller to form a polarizing plate protective film.

When introduced into the extruder from the feed hopper, it is preferable to prevent the oxidative decomposition or the like under vacuum or in an inert gas atmosphere under reduced pressure.

The extrusion flow rate is preferably adjusted stably by introducing a gear pump. In addition, a stainless steel fiber sintered filter is preferably used as the filter used for removing the foreign matter. The stainless steel fiber sintering filter is formed by integrally forming a stainless steel fiber body in an entangled state and then pressing and sintering the contact portions. The filtration accuracy can be adjusted by changing the density depending on the thickness of the fiber and the amount of compression.

Additives such as antioxidants and particles may be mixed with the resin in advance, or may be mixed in the extruder. In order to uniformly add it, it is preferable to use a mixing device such as a static mixer.

It is preferable that the polarizing plate protective film temperature on the touch roller side when nipping the polarizing plate protective film with the cooling roller and the elastic touch roller is equal to or higher than Tg (Tg + 110 deg. C) of the film. For the roller having the surface of the elastic body used for such a purpose, known rollers can be used.

The elastic touch roller is also referred to as a tightly closed rotating body. As the elastic touch roller, a commercially available one may be used.

When the film is peeled from the chill roller, it is preferable to control the tensile force to prevent deformation of the film.

The film obtained as described above is preferably stretched by the stretching operation after passing through a process in contact with the cooling roller.

As the stretching method, a known roller stretching machine, a tenter or the like can be preferably used. The stretching temperature is preferably in the range of Tg to (Tg + 60) 占 폚 of the resin constituting the film.

Before winding, the end portion may be slit and cut at a width corresponding to the product, and knurling (embossing) may be performed at both ends in order to prevent adhesion and scratching during winding. The knurling process can be performed by heating or pressing using a metal ring having a concavo-convex pattern on its side surface. Further, since the polarizing plate protective film is deformed and can not be used as a product, the grip portion of the clip at both end portions of the film is normally cut and reused.

&Lt; Physical properties of polarizing plate protective film &

<Hayes>

The polarizing plate protective film of the present invention preferably has a haze of 1.0% or less, more preferably 0.5% or less. By setting the haze to 1.0% or less, the transparency of the film becomes higher and it is advantageous that it becomes easier to use as a film for optical use.

Haze is measured by a haze meter (turbidity meter) (model: NDH 2000, manufactured by Nippon Denshoku Kogyo Co., Ltd.) in accordance with JIS K-7136.

<Yellow index; YI>

The polarizing plate protective film of the present invention preferably has YI of 1.0 or less, more preferably 0.5 or less. By setting the YI to 1.0 or less, the transparency of the film becomes higher and it is advantageous to be more easily used as a film for optical use. In particular, the production of the polarizing plate protective film of the present invention by the solution casting method is a preferable production method from the viewpoint of reducing YI.

The yellow index (YI) referred to in the present invention can be obtained by the method described in JIS K7105-6.3. As a specific method of measuring the yellow index value, the tristimulus values X, Y and Z of the color are obtained using a spectrophotometer U-3200 manufactured by Hitachi Seisakusho Co., Ltd. and a saturation calculation program, and the yellow index value .

Yellow index (%) = 100 (1.28X-1.06Z) / Y

&Lt; Total light transmittance >

The total light transmittance of the polarizing plate protective film is preferably 90% or more, and more preferably 93% or more. The total light transmittance can be measured according to JIS 7573 &quot; Plastics - Method for obtaining total light transmittance and total light reflectance &quot;.

<Equilibrium moisture content>

The polarizing plate protective film of the present invention preferably has an equilibrium moisture content of 3% or less at 25 캜 and 55% relative humidity, and more preferably 2% or less. By setting the equilibrium moisture content to 3% or less, it is preferable because it is easy to cope with humidity change and optical properties and dimensions are hardly changed.

&Lt; Film length, width, film thickness >

The polarizing plate protective film of the present invention is preferably long, and more specifically, preferably has a length of about 100 to 10000 m, and is wound in a roll shape. The width of the polarizing plate protective film of the present invention is preferably 1 m or more, more preferably 1.4 m or more, and particularly preferably 1.4 to 4 m.

The film thickness of the film is preferably in the range of 10 to 100 mu m, more preferably in the range of 10 to 60 mu m, from the viewpoints of reduction in thickness of the display device and productivity. If the film thickness is 10 mu m or more, a film strength or phase difference of a certain level or more can be produced. When the film thickness is 100 mu m or less, a desired retardation is provided, and the present invention can be applied to thinning of polarizing plates and display devices. In order to balance the bend unevenness and the thin film, it is preferably in the range of 20 to 50 mu m.

<Water vapor permeability>

The water vapor permeability is, 300g / m ² · day is preferably less than or equal to, 200g / m ² · more preferably not more than day, and the range of 10 to 100g / m ² · day in the 40 ℃ 90% RH of the polarizing plate protective film, This is particularly preferable in suppressing bend unevenness. This is for suppressing the dimensional change of the polarizer due to the moisture permeated in a high temperature and high humidity environment. The water vapor permeability is measured under the conditions of 40 DEG C and 90% RH in accordance with the method described in JIS Z 0208.

The moisture permeability of the polarizing plate protective film can be adjusted by, for example, the content ratio of the structural units derived from an aromatic vinyl monomer in the copolymer. In order to lower the moisture permeability, for example, the content ratio of the structural units derived from an aromatic vinyl monomer in these polymers may be increased.

<Tear strength>

The tear strength of the polarizing plate protective film under 23 캜 and 55% RH is preferably 15 mN or more, more preferably 20 mN or more, and still more preferably 30 mN or more. The upper limit of the tear strength is, for example, about 50 mN.

The tear strength of the polarizing plate protective film can be measured by the following method. That is, the polarizing plate protective film is cut out to obtain a sample film having a width of 50 mm and a length of 64 mm. The sample film is subjected to a humidity control at 23 ° C and 55% RH for 24 hours, and then Elmendorf tear strength is measured according to ISO6383 / 2-1983. The elemendorf tear strength can be measured using a weight tear tester manufactured by Toyo Seiki Co., Ltd. The tear strength can be obtained as an average value of the tear strength in the longitudinal direction (MD direction) of the film under 23 ° C and 55% RH and in the transverse direction in the film width direction (TD direction).

The tear strength of the polarizing plate protective film can be adjusted by, for example, the molecular weight of the copolymer or other resin. In order to increase the tear strength, for example, the molecular weight of the copolymer or other resin may be increased.

«Polarizer»

The polarizing plate protective film of the present invention is characterized in that it can be bonded to a polarizer using either a polyvinyl alcohol-based adhesive or an active energy ray-curable adhesive.

Therefore, in the polarizing plate of the present invention, it is preferable that the polarizing plate protective film of the present invention is bonded to at least one surface of the polarizer using a water-soluble or UV-curable adhesive.

It is more preferable that the cellulose ester type retardation film is bonded to the polarizer using a water-soluble or active energy ray-curable adhesive on the surface of the polarizer opposite to the surface to which the polarizing plate protective film is bonded, From the viewpoints of optical properties and optical properties.

Further, in the present invention, when the outer film (polarizing plate protective film) is a film having low moisture permeability and the inner film (retardation film) is made of a cellulose ester film, the influence of moisture from the outside can be reduced, The moisture of the polarizing plate can be easily released, and the durability against the humidity fluctuation of the polarizing plate can be improved.

Accordingly, the polarizing plate of the present invention is a polarizing plate protective film of the present invention and a structure in which a polarizer is sandwiched between the cellulose ester type retardation film of the present invention to improve durability, suppress bend unevenness, and impart excellent visibility to the liquid crystal display Which is a preferable form.

When the polarizing plate of the present invention is used as a polarizing plate on the viewer side, it is preferable that the film on the viewer side of the polarizing plate forms a functional layer such as an antiglare layer or a clear hard coating layer, an antireflection layer, an antistatic layer, .

<Polarizer>

The polarizer, which is a main component of the polarizing plate of the present invention, is a device that allows only light of a polarization plane in a certain direction to pass. A typical polarizer currently known is a polyvinyl alcohol polarizing film. The polyvinyl alcohol polarizing film includes a polyvinyl alcohol film stained with iodine and a dichroic dye stained.

As the polarizer, a polarizer in which a polyvinyl alcohol aqueous solution is formed, uniaxially stretched, dyed, uniaxially stretched, and preferably subjected to a durability treatment with a boron compound can be used. The film thickness of the polarizer is preferably in the range of 5 to 15 mu m, particularly preferably in the range of 5 to 10 mu m.

Further, an ethylene-modified polyvinyl alcohol having an ethylene unit content of 1 to 4 mol%, a degree of polymerization of 2000 to 4000 and a saponification degree of 99.0 to 99.99 mol% described in JP-A-2003-248123 and JP-A-2003-342322 Alcohol is also preferably used. Among them, an ethylene-modified polyvinyl alcohol film having a hot water cutting temperature of 66 to 73 占 폚 is preferably used. The polarizer using the ethylene-modified polyvinyl alcohol film is excellent in polarization performance and durability, and has less color unevenness and is particularly preferably used in a large-sized liquid crystal display device.

&Lt; Polarizer of laminated film type &

The polarizing plate of the present invention is preferably made of a thin film, and the thickness of the polarizer is preferably in the range of 2 to 15 탆 from the viewpoint of achieving both strength and thinning of the polarizing plate.

As such a polarizer of a thin film, it is preferable to produce a laminated film-type polarizer by the method described in Japanese Patent Laid-Open Nos. H11-100161, 4691205, 4751481, and 4804589 Do.

&Quot; Method for producing polarizer &quot;

[Production of polarizing plate using watercolor]

The polarizing plate of the present invention can be manufactured by a general method. A polarizing plate protective film of the present invention is subjected to a surface treatment such as corona treatment, plasma treatment or excimer light treatment on the polarizer side, and at least one surface of the polarizer produced by immersion stretching in an iodine solution is coated with a completely saponified polyvinyl alcohol aqueous solution (Watercolor).

In this case, similarly, it is preferable that the following retardation film and the polarizer are bonded together by a completely saponified polyvinyl alcohol aqueous solution (watercolor). When the retardation film is a cellulose ester film, it is preferable that the surface is saponified.

It is preferable that the direction of bonding with the polarizer is such that, for example, the absorption axis of the polarizer and the slow axis of the polarizing plate protective film are orthogonal to each other.

Another polarizing plate protective film can be bonded to the other surface of the polarizer. For example, as a conventional polarizing plate protective film, commercially available cellulose ester films (for example, Konica Minolta Tact KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC4FR, KC4KR, KC4DR, KC4SR, KC8UY, KC6UY, KC6UA, KC4UY KC4UXW-RHA-NC, KC8UXW-RHA-NC, KC8UXW-RHA, KC8UXW-RHA-C, KC8UXW-RHA-K, KC8UY-HA, KC8UY-HA and KC8UY-HA.

<Retardation film>

It is preferable to dispose a retardation film on one surface of the polarizer in order to improve visibility such as enlargement of viewing angle and improvement of contrast, etc. in a VA type liquid crystal display device.

The retardation film is not particularly limited and may be, for example, a cellulose ester film. Examples of the cellulose ester contained in the cellulose ester film include cellulose triacetate, cellulose diacetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate benzoate, cellulose acetate propionate benzoate, cellulose propionate, cellulose butyrate , Cellulose acetate biphenylate, cellulose acetate propionate biphenylate, and the like.

The cellulose ester preferably has a total acyl group substitution degree in the range of 1.5 to 2.5, more preferably both of the following formulas (a) and (b).

(A) 2.0? X + Y? 2.5

(B) 0? Y? 1.5

(Wherein X represents the substitution degree of the acetyl group and Y represents the degree of substitution of the propionyl group or the butyryl group, or a mixture thereof)

The weight average molecular weight (Mw) of the cellulose ester is preferably 75,000 or more, more preferably 100,000 to 1,000,000, and particularly preferably 100,000 to 500,000 from the viewpoints of film strength and appropriate viscosity at the time of film formation .

The cellulose ester film may be a single layer film; Or a laminated film. When the cellulose ester film is a laminated film, it is preferable that the cellulose ester film is a laminate of a core layer comprising a cellulose ester as a main component having a low degree of substitution and a skin layer having a cellulose ester as a main component arranged on both sides thereof. The cellulose ester having a low substitution degree preferably satisfies the above-mentioned formulas (a) and (b), and the cellulose ester having a high conversion degree preferably has a total acyl group substitution degree of more than 2.5, more preferably in a range of 2.7 to 2.98 , And it is preferable that all the acyl groups contained in the cellulose ester are acetyl groups.

The retardation of the retardation film can be set according to the type of the liquid crystal cell to be combined. For example, the retardation value Ro in the in-plane direction measured at a wavelength of 590 nm at 23 占 폚 RH and 55% RH is preferably in the range of 30 to 150 nm, and the retardation value Rt in the thickness direction And preferably in the range of 70 to 300 nm. The retardation film having a retardation value within the above range can be preferably used as a retardation film such as a VA type liquid crystal cell. Ro and Rt are defined as described above.

The thickness of the retardation film is not particularly limited, but is preferably in the range of 10 to 250 mu m, more preferably in the range of 10 to 100 mu m, and particularly preferably in the range of 30 to 60 mu m.

[Production of polarizing plate using active energy ray-curable adhesive]

In the polarizing plate of the present invention, it is preferable that at least one of the above-described polarizing plate protective film and polarizer of the present invention is bonded by an active energy ray curable adhesive. In this case, it is preferable that the retardation film and the polarizer are similarly bonded by an active energy ray-curable adhesive. It is also preferable that they are bonded by the same kind of active energy ray-curable adhesive.

In the present invention, application of the active energy ray-curable adhesive to the polarizing plate protective film of the present invention and the polarizer, or to the bonding of the retardation film and the polarizer, is advantageous in high productivity and easy to suppress deformation of the polarizing plate, Can be obtained.

(Composition of active energy ray curable adhesive)

As the active energy ray curable adhesive composition applicable to the production of the polarizing plate, there can be cited an optical radiation polymerization type composition using photo radical polymerization, a photo cationic polymerization type composition using photo cation polymerization and a hybrid type composition using photo radical polymerization and photo cation polymerization Is known.

Examples of the photo-radical polymerization type composition include compositions containing a radical polymerizing compound containing a polar group such as a hydroxyl group or a carboxyl group and a radically polymerizable compound containing no polar group in a specific ratio described in JP-A-2008-009329 Is known. In particular, the radical polymerizing compound is preferably a compound having a radically polymerizable ethylenic unsaturated bond. Preferable examples of the compound having a radically polymerizable ethylenically unsaturated bond include a compound having a (meth) acryloyl group. Examples of the compound having a (meth) acryloyl group include N-substituted (meth) acrylamide-based compounds, (meth) acrylate-based compounds and the like. (Meth) acrylamide means acrylamide or methacrylamide.

As the photo cationic polymerization type composition, there may be mentioned (a) a cationic polymerizable compound, (?) A photo cationic polymerization initiator, (?) A photoacid generator having a wavelength longer than 380 nm (隆) naphthalene-based photo-sensitization assistant, and the active energy ray-curable adhesive composition containing the components of the photo-sensitization assistant (隆). However, other active energy ray-curable adhesives may be used.

As the active ray curable adhesive for use in the present invention, it is preferable to use an ultraviolet curable adhesive as described in the above publication.

Hereinafter, an example of a method for producing a polarizing plate using an active energy ray-curable adhesive will be described.

As the polarizer production process of the present invention,

1) an adhesive applying step of applying the following active energy ray-curable adhesive to at least one of the bonding surfaces of the polarizer and the polarizing plate protective film of the present invention;

2) a polarizer and a polarizing plate protective film are bonded to each other with an adhesive layer interposed therebetween;

3) a curing step of curing the adhesive layer in a state in which the polarizer and the polarizing plate protective film are adhered via the adhesive layer,

. Further, the surface to which the polarizer of the polarizing plate protective film is adhered may be subjected to the following pre-treatment step facilitating the adhesion.

(Pre-processing step)

In the preprocessing step, the surface of the polarizing plate protective film adhered to the polarizer is subjected to the adhesion facilitating treatment. When the polarizing plate protective film 102 and the retardation film 105 are bonded to both surfaces of the polarizer 104 via the active energy ray curable adhesives 103A and 103B as shown in Fig. 2, The adhesion facilitating treatment is performed on the adhesion surfaces of the polarizing plate protective film 102 and the retardation film 105.

In the adhesive coating step, which is the next step, the surface subjected to the adhesion facilitating treatment is treated as a bonding surface with the polarizer. Therefore, among the surfaces of both surfaces of the polarizing plate protective film, the surface bonding to the active energy ray curable resin layer 103A Processing is performed. Examples of the adhesion facilitating treatment include corona treatment, plasma treatment, excimer light treatment, and the like.

(Adhesive application step)

In the adhesive applying step, the active energy ray-curable adhesive is applied to at least one side of the bonding surface between the polarizer and the polarizing plate protective film. When the active energy ray-curable adhesive is applied directly to the surface of the polarizer or the polarizing plate protective film, the application method is not particularly limited. For example, various wet coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used. Also, a method may be employed in which an active energy ray-curable adhesive is poured between the polarizer and the polarizing plate protective film, and then the film is uniformly spread by pressing with a roller or the like.

(Bonding step)

After the active energy ray-curable adhesive is applied by the above method, it is treated in the bonding step. In this bonding step, for example, when the active energy ray-curable adhesive is applied to the surface of the polarizer in the previous coating step, the polarizing plate protective film is superimposed on the adhesive. When the active energy ray-curable adhesive is applied to the surface of the polarizing plate protective film in the previous coating step, the polarizer is superimposed thereon. When the active energy ray-curable adhesive is softened between the polarizer and the polarizing plate protective film, the polarizing plate and the polarizing plate protective film are superimposed in this state. A polarizing plate protective film and a retardation film are adhered to both sides of a polarizer via an active energy ray curable adhesive in the case where an active energy ray curable adhesive is used on both sides, Overlap. Normally, when the polarizing plate protective film is superimposed on one side of the polarizer (in the case of superimposing the polarizing plate protective film and the retardation film on both the polarizer side and the polarizing plate protective film side and also on the polarizer side) The polarizing plate protective film and the retardation film side) with a roller or the like. As for the material of the roller, metal or rubber can be used. The rollers disposed on both sides may be the same material or different materials.

(Curing Process)

In the curing step, an active energy ray is irradiated to an uncured active energy ray-curable adhesive to form a cationic polymerizable compound (for example, an epoxy compound or an oxetane compound) or a radical polymerizable compound (for example, an acrylate compound , An acrylamide-based compound, and the like) is cured, and the polarizer and the polarizing plate protective film or the polarizer and the retardation film are bonded to each other via the active energy ray-curable adhesive. When the polarizing plate protective film is bonded to one surface of the polarizer, the active energy ray may be irradiated from either the polarizer side or the polarizing plate protective film side. When the polarizing plate protective film and the retardation film are bonded to both surfaces of the polarizer, the active energy rays are irradiated on the both surfaces of the polarizer with the polarizing plate protective film and the retardation film superimposed on each other through the active energy ray curable adhesive, It is advantageous to simultaneously cure the active energy ray-curable adhesive.

As the active energy ray to be applied for curing, visible ray, ultraviolet ray, X ray, electron ray and the like can be used, but electron beam and ultraviolet ray are preferably used because they are easy to handle and have a sufficient curing speed.

Examples of the ultraviolet light source include a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, a super high pressure mercury lamp, a carbon arc lamp, a metal halide lamp, and a xenon lamp. An ArF excimer laser, a KrF excimer laser, an excimer lamp, or a synchrotron radiation can also be used. Among these, ultrahigh pressure mercury lamps, high pressure mercury lamps, low pressure mercury lamps, xenon arc lamps, and metal halide lamps are preferably used.

The electron beam may be 50 to 1000 keV, preferably 100 to 1000 keV, emitted from various kinds of electron beam accelerators such as a Cocraft Walton type, a Bandegraph type, a resonance type, an insulating core type, a straight type, a dynamictron type, And an electron beam having an energy in the range of 300 keV.

Irradiation conditions of the electron beam may be any suitable condition provided that the adhesive can be cured. For example, in the electron beam irradiation, the acceleration voltage is preferably in the range of 5 to 300 kV, more preferably in the range of 10 to 250 kV. If the acceleration voltage is 5 kV or more, the electron beam sufficiently reaches the adhesive and desired curing conditions can be obtained. If the acceleration voltage is 300 kV or less, the penetration force passing through the adhesion unit is not excessively strengthened. It is possible to suppress damage.

The irradiation dose is in the range of 5 to 100 kGy, more preferably in the range of 10 to 75 kGy. When the radiation dose is 5 kGy or more, curing of the active energy ray curable adhesive becomes sufficient, and when it is 100 kGy or less, the polarizing plate protective film and the polarizer are not damaged, Can be obtained.

The irradiation condition of the ultraviolet ray may be any appropriate condition as long as it is a condition capable of curing the active energy ray curable adhesive. Dose of ultraviolet rays is, the accumulated light quantity preferably in the range of 50 to 1500mJ / cm ^2, more preferably in a range of 100 to 500mJ / cm ^2.

When the above production method is carried out in a continuous line, the line speed varies depending on the curing time of the active energy ray-curable adhesive, but is preferably in the range of 1 to 500 m / min, more preferably in the range of 5 to 300 m / min And preferably in the range of 10 to 100 m / min. When the line speed is 1 m / min or more, appropriate productivity can be ensured, damage to the transparent polarizing plate protective film can be suppressed, and a polarizing plate capable of enduring durability test and the like can be manufactured. When the line speed is 500 m / min or less, the curing of the resulting adhesive is sufficient, and the desired adhesive property can be obtained.

In the polarizing plate thus obtained, the thickness of the active energy ray-curable adhesive layer is not particularly limited, but is usually in the range of 0.01 to 10 탆, preferably in the range of 0.5 to 5 탆.

&Quot; Liquid crystal display device &

In the liquid crystal display device of the present invention, at least a first polarizing plate (A), a liquid crystal cell and a second polarizing plate (B) are arranged in this order from the viewing side, and both the polarizing plate (A) The first polarizing plate A is composed of a polarizing plate protective film T1, a polarizer and a retardation film T2 from the viewing side, and the second polarizing plate B is composed of a retardation film T3, It is preferable that the polarizing plate protective film Tl and the polarizing plate protective film T4 are constituted by a polarizer and a polarizing plate protective film T4 and that the polarizing plate protective film T1 and the polarizing plate protective film T4 are polarizing plate protective films comprising the constitution specified in the present invention.

It is preferable that the polarizing plate protective film (T1) has a functional layer such as a hard coating layer, an antireflection layer, or an antiglare layer on the viewing side.

Since the polarizing plate protective film of the present invention is excellent in water resistance, heat resistance and planarity, the glass substrate constituting the liquid crystal cell can be made thin by providing the polarizing plate of the present invention in the liquid crystal display, and as a result, Can be obtained.

As the glass substrate that can be used for the liquid crystal cell, for example, soda lime glass, silicate glass, and the like are preferable, and silicate glass is preferable. Specifically, silica glass or borosilicate glass is more preferable.

The glass constituting the glass base material is preferably an alkali-free glass substantially containing no alkali component, specifically, a glass having an alkali component content of not more than 1000 ppm. The content of the alkali component in the glass base material is preferably 500 ppm or less, and more preferably 300 ppm or less. In the glass base material containing an alkali component, cation exchange occurs at the surface of the film, and the white turbidity phenomenon is likely to occur. As a result, the density of the surface layer of the film is likely to be lowered, and the glass base material is liable to be broken.

The thickness of the glass base material of the liquid crystal cell constituting the liquid crystal display device is preferably in the range of 0.4 to 0.6 mm. Such a thickness is preferable in that it can contribute to the formation of a thin liquid crystal display device.

The glass substrate can be formed by a known method, for example, a float method, a down-draw method, an overflow down-draw method, or the like. Above all, the overflow down draw method is preferable in that the surface of the glass substrate does not contact the molded member at the time of molding and scratches are not easily formed on the surface of the obtained glass substrate.

Such a glass substrate is also available as a commercial product. For example, an alkali-free glass AN100 (thickness 500 mu m) manufactured by Asahi Glass Co., a glass substrate EAGLE XG (r) Slim (thickness 300 mu m, Etc.), a glass substrate (thickness: 100 to 200 mu m) manufactured by Nippon Denshikagaras Co., Ltd., and the like.

By using the polarizing plate of the present invention, it is possible to provide a liquid crystal display device which suppresses display irregularity (bend unevenness) and has excellent visibility such as front contrast even when the thin film glass substrate is used for a liquid crystal cell, Can be obtained.

Hereinafter, the outline of the configuration of a liquid crystal display device having a polarizing plate of the present invention will be described.

3 is a schematic cross-sectional view showing an example of the configuration of the liquid crystal display device 106 having the polarizing plate 101 of the present invention described above.

3, the liquid crystal cell 107 is sandwiched between the retardation film 105 constituting the polarizing plate 101A described in Fig. 2 and the retardation film 105 constituting the polarizing plate 101B, 106).

3, in the polarizing plate 101A on the liquid crystal cell 107, a polarizing plate protective film 102 is disposed on the surface portion as an optical film, which is referred to as a polarizing plate protective film T1, A retardation film 105 is disposed on the lower portion of the retardation film 104, which is referred to as a retardation film T2.

It is preferable that the above-described functional layer is formed on the viewer side of the polarizing plate protective film 102 which is T1.

A polarizing plate 101B is disposed on the opposite side of the liquid crystal cell 107 and a polarizing plate protective film 102 is disposed as an optical film from the outermost surface. In the present invention, this is referred to as a polarizing plate protective film T4, A retardation film 105 is disposed under the polarizer 104 (liquid crystal cell side) and is called a retardation film T3.

In the liquid crystal display device having such a constitution, in the polarizing plate protective film of the present invention, the polarizing plate protective film 102 (polarizing plate protective film T1) of the polarizing plate 101A and the polarizing plate protective film 102 ( Polarizing plate protective film T4).

The bonding of the surface of the polarizing plate on the retardation film side and the surface of at least one of the liquid crystal cells can be performed by a known method. In some cases, they may be bonded via an adhesive layer or an adhesive layer.

A liquid crystal display device of various driving modes such as STN, TN, OCB, HAN, VA (MVA, PVA), IPS and OCB can be used for the mode (driving method) of the liquid crystal display device. In particular, it is preferably a VA (MVA, PVA) type liquid crystal display.

The joining direction of the polarizing plate in the VA mode liquid crystal display device can be performed with reference to Japanese Patent Application Laid-Open No. 2005-234431.

By using the polarizing plate according to the present invention in these liquid crystal display devices, it is possible to obtain a liquid crystal display device having excellent visibility such as non-uniformity of the liquid crystal display device even in the case of a liquid crystal display device of a 30 screen type or larger.

Example

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto. In the examples, "part" or "%" is used, and unless otherwise stated, "part by mass" or "% by mass"

1. Material of polarizing plate protective film

(1) Synthesis and blending of copolymers

&Lt; Preparation of Copolymer 1 >

&Lt; Copolymer (A) >

(Styrene-acrylonitrile copolymer)

In a fully mixed continuous reactor equipped with a stirrer, a monomer mixture containing styrene and acrylonitrile in a predetermined mixing ratio was mixed with ethylbenzene as a solvent, and the reaction rate was kept constant at a constant rate, Polymerization was carried out for 2 hours.

The obtained polymerization solution was continuously fed to an extruder and subjected to extrusion molding, and unreacted monomers and solvent were recovered from the extruder to obtain pellets of a styrene-acrylonitrile copolymer.

The obtained copolymer was colorless and transparent. As a result of the composition analysis by the following method, the content of the styrene unit was 70 mol% and the content of the acrylonitrile unit was 30 mol%. As a result of measurement of the weight average molecular weight by GPC (in terms of polystyrene of GPC system manufactured by Doso Co., Ltd.), the weight average molecular weight was 200,000.

The content ratio of the constituent units of the obtained copolymer (A) was measured by the following method.

In the total ion chromatogram, the ratios of the areas of the peaks derived from "styrene" and "acrylonitrile" to the "total sum of the areas of all the peaks detected from the polymer to be measured" And the content of nitrile units was determined.

&Lt; Preparation of Copolymer 2 >

A styrene-acrylonitrile copolymer having a styrene unit content of 60 mol% and an acrylonitrile unit content of 40 mol% was prepared in the production of the copolymer 1, and a copolymer having a weight average molecular weight of 200,000 as shown in Table 1 2.

&Lt; Preparation of Copolymer 3 >

A copolymer having a styrene unit content of 45 mol%, an acrylonitrile unit content of 30 mol%, and an N-phenylmaleimide unit content of 25 mol% was produced in the production of the copolymer 1, Thereby preparing Copolymer 3 having a weight average molecular weight of 200,000.

&Lt; Preparation of copolymer 4 >

A copolymer having a styrene unit content of 55 mol%, an acrylonitrile unit content of 20 mol%, and an N-phenylmaleimide unit content of 25 mol% was prepared in the production of the copolymer 3, To prepare Copolymer 4 having a weight average molecular weight of 200,000.

&Lt; Preparation of copolymer 5 >

A copolymer having a styrene unit content of 50 mol%, an acrylonitrile unit content of 25 mol%, and a cyclohexyl maleimide unit content of 25 mol% was produced in the production of the copolymer 3, Thereby preparing Copolymer 5 having a weight average molecular weight of 200,000.

&Lt; Preparation of Copolymer 6 >

A copolymer having a styrene unit content of 55 mol%, an acrylonitrile unit content of 25 mol%, and a benzyl maleimide unit content of 20 mol% was produced in the production of the copolymer 3, and the weight Copolymer 6 having an average molecular weight of 200,000 was prepared.

&Lt; Preparation of copolymer 7 >

In the production of the copolymer 1, a copolymer having an α-methylstyrene unit content of 70 mol% and an acrylonitrile unit content of 30 mol% was prepared by using α-methylstyrene instead of styrene, To obtain Copolymer 7 having a weight average molecular weight of 150,000.

&Lt; Preparation of Copolymer 8 >

A copolymer having a styrene unit content of 70 mol% and methacrylonitrile in place of acrylonitrile and a methacrylonitrile unit content of 30 mol% was prepared in the preparation of the copolymer 1, To prepare Copolymer 8 having a weight average molecular weight of 200,000.

&Lt; Preparation of Copolymer 9 >

&Lt; Copolymer (A) >

A styrene-acrylonitrile copolymer having a styrene unit content of 70 mol% and an acrylonitrile unit content of 30 mol% was prepared in the same manner as in the copolymer 1. In the same way, a copolymer (A) having a weight average molecular weight of 200,000 as shown in Table 1 was prepared in the same manner.

&Lt; Copolymer (B) >

52 parts by mass of N-phenylmaleimide, 73 parts by mass of styrene, 0.01 part by mass of n-dodecylmercaptan as a polymerization chain transfer agent, and 50 parts by mass of a polymerization initiator were added to a reaction apparatus equipped with a stirrer, a temperature sensor, 100 parts by mass of methyl isobutyl ketone was added as a solvent, and the mixture was heated to 80 DEG C while passing nitrogen through it. Azobis (2-methylisobutyronitrile) was added as a polymerization initiator at a point of time when the reflux accompanied by the elevated temperature was started, solution polymerization was carried out for 7 hours under reflux at about 80 to 85 ° C I made it.

Subsequently, the polymerization solution thus obtained was dried under reduced pressure at 240 ° C for 1 hour to obtain a transparent, transparent and transparent resin having a N-phenylmaleimide unit content of 30 mol% and a styrene unit content of 70 mol% To obtain a copolymer (B).

&Lt; Mixing Ratio of Copolymer (A) and Copolymer (B) >

The copolymer (A) and the copolymer (B) thus prepared were mixed at a mass ratio of 70:30 as shown in Table 1 to prepare Copolymer 9 shown in Table 1.

&Lt; Preparation of Copolymer 10 >

Copolymer 10 was prepared in the same manner as in Table 1 except that the mixing ratio of copolymer (A) and copolymer (B) was changed to 30:70 in the preparation of copolymer 9.

&Lt; Production of Copolymer 11 >

Except that the copolymer (B) alone (the mixing ratio of the copolymer (A) and the copolymer (B) was 0: 100) in the production of the copolymer 9, 11 was prepared.

&Lt; Preparation of Copolymer 12 >

&Lt; Copolymer (B) >

A copolymer (B) having a cyclohexylmaleimide unit content of 20 mol% and a methyl methacrylate content of 80 mol% and a weight average molecular weight of 150,000 was obtained in the same manner as in the copolymer 9.

&Lt; Mixing Ratio of Copolymer (A) and Copolymer (B) >

Except that the copolymer (B) alone (the mixing ratio of the copolymer (A) and the copolymer (B) was 0: 100) in the production of the copolymer 9, 12.

&Lt; Production of Copolymer 13 >

&Lt; Copolymer (A) >

A styrene-acrylonitrile copolymer having a styrene unit content of 70 mol% and an acrylonitrile unit content of 30 mol% was prepared in the same manner as in the copolymer 1. In the same way, a copolymer (A) having a weight average molecular weight of 200,000 as shown in Table 1 was prepared in the same manner.

&Lt; Copolymer (B) >

A copolymer (B) having a cyclohexylmaleimide unit content of 30 mol%, a styrene unit content of 70 mol%, and a weight average molecular weight of 150,000 was obtained in the same manner as in the copolymer 9.

&Lt; Mixing Ratio of Copolymer (A) and Copolymer (B) >

The copolymer (A) and the copolymer (B) thus prepared were mixed at a mass ratio of 70:30 as shown in Table 1 to prepare Copolymer 13 shown in Table 1.

&Lt; Preparation of Copolymer 14 >

&Lt; Copolymer (A) >

A styrene-acrylonitrile copolymer having a styrene unit content of 55 mol% and an acrylonitrile unit content of 45 mol% was prepared in the same manner as in the copolymer 1. In the same way, a copolymer (A) having a weight average molecular weight of 200,000 as shown in Table 1 was prepared in the same manner.

&Lt; Copolymer (B) >

(B) having a weight average molecular weight of 150,000, an N-phenylmaleimide unit content of 25 mol%, a styrene unit content of 55 mol%, an acrylonitrile unit content of 20 mol% ).

&Lt; Mixing Ratio of Copolymer (A) and Copolymer (B) >

The copolymer (A) and the copolymer (B) thus prepared were mixed at a mass ratio of 70:30 as shown in Table 1 to prepare the copolymer 14 shown in Table 1.

&Lt; Production of Copolymer 15 >

&Lt; Copolymer (A) >

A styrene-acrylonitrile copolymer having a styrene unit content of 55 mol% and an acrylonitrile unit content of 45 mol% was prepared in the same manner as in the copolymer 14. In the same way, a copolymer (A) having a weight average molecular weight of 200,000 as shown in Table 1 was prepared in the same manner.

&Lt; Copolymer (B) >

A copolymer (B) having a weight average molecular weight of 150,000, an N-phenylmaleimide unit content of 25 mol%, a styrene unit content of 55 mol%, an acrylonitrile unit content of 20 mol% ).

&Lt; Mixing Ratio of Copolymer (A) and Copolymer (B) >

The copolymer (A) and the copolymer (B) prepared above were mixed at a mass ratio of 90:10 as shown in Table 1 to prepare the copolymer 15 shown in Table 1.

&Lt; Preparation of Copolymer 16 >

&Lt; Copolymer (A) >

A styrene-acrylonitrile copolymer having a styrene unit content of 70 mol% and an acrylonitrile unit content of 30 mol% was prepared in the same manner as in the copolymer 1. In the same way, a copolymer (A) having a weight average molecular weight of 200,000 as shown in Table 1 was prepared in the same manner.

&Lt; Copolymer (B) >

A copolymer having a weight average molecular weight of 200,000 and an N-phenylmaleimide unit content of 20 mol%, a styrene unit content of 20 mol%, and a methyl methacrylate unit content of 60 mol% was obtained in the same manner as the copolymer ( B).

&Lt; Mixing Ratio of Copolymer (A) and Copolymer (B) >

The copolymer (A) and the copolymer (B) thus prepared were mixed at a mass ratio of 70:30 as shown in Table 1 to prepare a copolymer 16 shown in Table 1.

&Lt; Preparation of Copolymer 17 >

Copolymer (A) and copolymer (B) were prepared in the same manner as in the preparation of Copolymer 16.

&Lt; Mixing Ratio of Copolymer (A) and Copolymer (B) >

The copolymer (A) and the copolymer (B) thus prepared were mixed at a mass ratio of 50:50 as shown in Table 1 to prepare Copolymer 17 shown in Table 1.

&Lt; Preparation of copolymer 18 >

&Lt; Copolymer (A) >

A styrene-acrylonitrile copolymer having a styrene unit content of 70 mol% and an acrylonitrile unit content of 30 mol% was prepared in the same manner as in the copolymer 1. In the same way, a copolymer (A) having a weight average molecular weight of 200,000 as shown in Table 1 was prepared in the same manner.

&Lt; Copolymer (B) >

A copolymer (B (weight average molecular weight: 150,000) having a cyclohexylmaleimide unit content of 20 mol%, a styrene unit content of 20 mol% and a methyl methacrylate unit content of 60 mol% was obtained in the same manner as the copolymer ).

&Lt; Mixing Ratio of Copolymer (A) and Copolymer (B) >

The copolymer (A) and the copolymer (B) thus prepared were mixed at a mass ratio of 70:30 as shown in Table 1 to prepare a copolymer 18 shown in Table 1.

&Lt; Preparation of copolymer 19 >

A styrene-acrylonitrile copolymer having a styrene unit content of 90 mol% and an acrylonitrile unit content of 10 mol% was prepared in the production of the copolymer 1, and a copolymer of a weight average molecular weight of 250,000 shown in Table 1 19.

&Lt; Preparation of Copolymer 20 >

Copolymer 20, which is polymethyl methacrylate having a methyl methacrylate unit content of 95 mol% and a methacrylic acid unit content of 5 mol%, was prepared by a conventional method. The weight average molecular weight was 200,000, and used alone as shown in Table 1.

The constituent contents of the copolymers 1 to 20 thus prepared are shown in Table 1. The following abbreviations are used in the following tables.

St: Styrene

? -MSt:? -methyl styrene

AN: acrylonitrile

MN: methacrylonitrile

PMI: N-phenylmaleimide

CHMI: cyclohexylmaleimide

BzMI: Benzylmaleimide

MMA: methyl methacrylate

MA: methyl acrylate

<Measurement method of unreacted monomers>

The content of unreacted monomers contained in the copolymer (A) synthesized in the synthesized Copolymers 1 to 10, 13 to 19 was measured by the following method.

1) 0.1 g of the copolymer (A) is dissolved in 2 ml of acetone and sonicated for 30 minutes. To this solution, 50 ppm of ethylene glycol monomethyl ether as an internal standard component is added, and the solution is made up to 10 ml with hexane to prepare a sample solution.

2) The content (mass%) of unreacted monomers relative to the total mass of the copolymer (A) contained in the sample solution is measured by GC / MS. The GC / MS measurement apparatus and measurement conditions are as follows.

Device: HP 6890GC / HP 5973MSD (manufactured by Hewlett-Packard Company)

Column: DB-624 (0.25 mm id. X 30 ml) manufactured by J &

Oven program: 40 캜 (3 min) -20 캜 / min-230 캜 (8 min)

Inj: 160 ° C

AUX: 250 ° C

The composition of Copolymers 1 to 20 and the measurement results of the unreacted monomers of Copolymers 1 to 10 and 13 to 19 are shown in Table 1.

(2) Release aid (Compound 1)

1-1: Elecut S-412-2 (manufactured by Takemoto Oil & Fat Co., Ltd.): Sodium dodecylbenzenesulfonate

1-2: EPC 750 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.): Nonionic surfactant

1-3: Stearyl alcohol

(3) Rubber particles (Compound 2)

2-1: Toughprene 126S (manufactured by Asahi Kasei Chemicals Co., Ltd.) Styrene-butadiene copolymer

2-2: TR2003 (manufactured by JSR Corporation) Styrene-butadiene copolymer

2-3: Substrate 1

2-4: Substrate 2

<Particle 1: Acrylic particles synthesized by the following method>

(Acrylic Particles C1)

38.2 liters of ion-exchanged water and 111.6 g of sodium dioctylsulfosuccinate were charged into a reactor equipped with a reflux condenser with an internal volume of 60 liters and heated to 75 DEG C under a nitrogen atmosphere while stirring at a rotational speed of 250 rpm, I was left without. And 0.36 g of ammonium persulfate (APS) were added and stirred for 5 minutes. After stirring for 5 minutes, 1657 g of methyl methacrylate (MMA), 21.6 g of n-butyl acrylate (BA) and 1.68 g of allyl methacrylate After the exothermic peak was detected, the mixture was held 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 mixture of 8105 g of BA, 31.9 g of polyethylene glycol diacrylate (PEGDA, molecular weight 200) and 264.0 g of ALMA was continuously added over 120 minutes, After completion of the polymerization, the polymerization was continued for 120 minutes to complete the polymerization of the soft layer.

Subsequently, 1.32 g of APS was added, and after stirring for 5 minutes, a mixture of monomers including 2106 g of MMA and 201.6 g of BA was continuously added over 20 minutes, and after completion of addition, polymerization was continued for 20 minutes to polymerize the outermost hard layer 1 It was completed.

Subsequently, 1.32 g of APS was introduced and after 5 minutes, a mixture of monomers containing 3148 g of MMA, 201.6 g of BA and 10.1 g of n-octylmercaptan (n-OM) was continuously added over a period of 20 minutes, And maintained for 20 minutes. Subsequently, the temperature was raised to 95 占 폚 and held for 60 minutes to complete the polymerization of the outermost hard layer 2.

The polymer latex thus obtained was put into an aqueous solution of 3 mass% sodium sulfate and subjected to salting out and solidification, followed by dehydration and washing, followed by drying to obtain acrylic particles having a three-layer structure. The average particle diameter determined by the absorbance method was found to be 100 nm.

<Particle 2: Elastomeric organic fine particles synthesized by the following method>

(Elastic organic fine particles (B1))

70 parts of deionized water, 0.5 part of sodium pyrophosphate, 0.2 part of potassium oleate, 0.005 part of ferrous sulfate, 0.2 part of dextrose, 0.1 part of p-mentholhydroperoxide, And 28 parts of 3-butadiene were added, and the mixture was heated to 65 占 폚 and polymerized for 2 hours. Subsequently, 0.2 part of p-mentholhydroperoxide was added to the obtained reaction mixture, and then a mixture of 72 parts of 1,3-butadiene, 1.33 parts of potassium oleate and 75 parts of deionized water was continuously added dropwise over 2 hours. The reaction was initiated for 21 hours from the start of polymerization to obtain a butadiene rubber polymer latex having a volume average particle diameter of 0.240 탆.

Next, 120 parts of deionized water, 50 parts of the butadiene rubber polymer latex as solid components, 1.5 parts of potassium oleate and 0.6 parts of sodium formaldehyde sulfoxylate (SFS) were fed into a polymerization vessel equipped with a condenser and a stirrer, The inside was sufficiently replaced with nitrogen gas. Subsequently, the internal temperature was raised to 70 占 폚, and then a mixed monomer solution containing 36.5 parts of styrene and 13.5 parts of acrylonitrile, 0.27 parts of cumene hydroperoxide and 20 parts of deionized water was separately treated for 2 hours And the polymerization was carried out while continuously dropping. After completion of the dropwise addition, the internal temperature was raised to 80 DEG C and polymerization was continued for 2 hours. Subsequently, the mixture was cooled until the internal temperature became 40 DEG C, and then passed through a 300-mesh netting network to obtain an emulsion-polymerized liquid of elastic organic fine particles. The emulsion-polymerized liquid of the obtained elastic organic fine particles was salted and coagulated with calcium chloride, washed with water and dried to obtain elastomeric fine particles in the form of powder. The volume average particle diameter of the elastic organic fine particles was 0.260 mu m.

2. Fabrication of Polarizer Protective Film

(Production of polarizing plate protective film 101)

The following components were sufficiently dissolved while stirring and heating to prepare Dope 1.

(Composition of Dope 1)

Copolymer 1 100 parts by mass

(UV-absorbing agent) of 2- (2H-benzotriazol-2-yl) -6- (1 -methyl- 1 -phenylethyl) -4- (1,1,3,3-tetramethylbutyl) phenol (BASF) Ti928 manufactured by Japan) 3.0 parts by mass

Matrigel R812 (manufactured by Nippon Aerosil Co., silica particles, average particle diameter 8 nm) 0.30 parts by mass

Separation aid Elecut S-412-2 (sodium dodecylbenzenesulfonate, manufactured by Takemoto Yushi) 0.20 parts by mass

Rubber particles Toughprene 126S (manufactured by Asahi Kasei Chemicals Co., Ltd.) Styrene-butadiene copolymer       1 part by mass

Dichloromethane  150 parts by mass

ethanol    5 parts by mass

The prepared dope 1 was uniformly plied to a stainless steel band support at a temperature of 22 캜 and a width of 2 m by using a belt softener. In the stainless steel band support, the solvent was evaporated until the amount of the residual solvent became 50%, and the obtained film was peeled off on a stainless steel band support at a peeling tension of 162 N / m.

Subsequently, the peeled film material was evaporated at 35 캜 and dried at a drying temperature of 135 캜 while being stretched by 1.25 times in the transverse direction (TD direction) by tenter stretching. The amount of the residual solvent when the stretching by the stretching by the zone was started was 20.0%, and the amount of the residual solvent when the stretching by the tenter was started was 8.0%.

After stretching with a tenter, the film was subjected to a relaxation treatment at 130 占 폚 for 5 minutes, and the drying was then carried out while conveying the drying zone at 120 占 폚 and 140 占 폚 by a plurality of rollers. The resulting film was slit to a width of 1.5 m, knurled at both ends of the film by 10 mm in width and 5 탆 in height, and then wound around a core to prepare a polarizing plate protective film 101. The thickness of the produced protective film 101 was 40 μm and the winding length was 4000 m.

(Production of polarizing plate protective films 102 to 125, 129 and 130)

The polarizing plate protective film 101 was prepared in the same manner as in the production of the polarizing plate protective film 101 except that the types (1 to 20) of the copolymer, the kind and amount of the compound 1 and the compound 2, and the film thickness were changed as shown in Table 3, respectively Films 102 to 125, 129 and 130 were produced.

(Production of polarizing plate protective film 126)

(Production of pellets)

Copolymer 1 100 parts by mass

UV absorber 2,2'-methylenebis [6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol] (Adeka, LA31, molecular weight 659)

3.0 parts by mass

Matte R972V (manufactured by Nippon Aerosil Co., Ltd., silica particles, average particle diameter 16 nm)

0.30 parts by mass

Separation aid Elecut S-412-2 (sodium dodecylbenzenesulfonate, manufactured by Takemoto Yushi) 0.20 parts by mass

Rubber particles Toughprene 126S (manufactured by Asahi Kasei Chemicals Co., Ltd.) Styrene-butadiene copolymer    1 part by mass

The material was dried in a vacuum Nauta mixer at 70 캜 under reduced pressure for 3 hours, and then cooled to room temperature. The obtained mixture was melted and kneaded at 235 DEG C with a twin-screw extruder, and extruded into a strand shape. The resin composition extruded into a strand shape was water-cooled and then cut to obtain pellets.

The resulting pellets were put into a single screw extruder and melted and kneaded at 250 캜 in a nitrogen atmosphere. Then, it was extruded from the die onto a first cooling roll having a surface temperature of 90 占 폚. Then, the resin extruded onto the first cooling roll was pressed by a touch roll. The surface temperature of the touch roll was set at 80 캜. Thereafter, the obtained resin was further cooled and solidified on the second and third cooling rolls to obtain a polarizing plate protective film 126 having a film thickness of 40 m.

(Production of polarizing plate protective films 127 and 128)

A polarizing plate protective film 127 having a film thickness of 40 占 퐉 was obtained in the same manner as the polarizing plate protective film 126 except that the copolymer 9 was used. Similarly, Polymeric protective film 128 was obtained using Copolymer 20.

&Lt; Evaluation of polarizing plate protective film &

The polarizing plate protective films 101 to 130 thus prepared were subjected to the following evaluations, and the results are shown in Table 2. &lt; tb &gt; &lt; TABLE &gt;

(1) Heat resistance

The heat resistance is evaluated by the glass transition temperature (Tg (占 폚) of the polarizing plate protective film, and the higher the Tg (占 폚), the better the heat resistance. The glass transition temperature (Tg (占 폚)) is measured using a differential scanning calorimeter DSC220 manufactured by Seiko Instruments Inc. according to JIS K-7121.

The sample film was set to about 10 mg and heated from room temperature to 250 캜 at a rate of 20 캜 / min under a nitrogen flow rate of 50 ml / min, held for 10 minutes (1st scan), then heated to 30 캜 at a rate of 20 캜 / The glass transition temperature (Tg) is obtained from the DSC curve of the obtained 3rd scan by holding the temperature for 10 minutes (2nd scan), raising the temperature to 20 占 폚 / min to 250 占 폚 (3rd scan)

The glass transition temperature (Tg) of each polarizing plate protective film measured as described above was evaluated according to the following criteria.

?: Glass transition temperature of 120 占 폚 or higher

?: Glass transition temperature is in the range of 110 占 폚 to 120 占

DELTA: Glass transition temperature is in the range of 100 DEG C or more and less than 110 DEG C

X: Glass transition temperature is less than 100 占 폚

(2) Hayes

Haze is measured with a haze meter (turbidity meter) (model: NDH 2000, manufactured by Nippon Denshoku Kogyo Co., Ltd.) in accordance with JIS K-7136.

(3) Yellow index (YI)

The yellow index (YI) is obtained by the method described in JIS K-7105-6.3. As a specific method of measuring the yellow index value, the tristimulus values X, Y and Z of the color are obtained using a spectrophotometry program or the like attached to a spectrophotometer U-3200 manufactured by Hitachi Seisakusho, and the yellow index value .

Yellow index = 100 (1.28X-1.06Z) / Y

(4) Bending resistance

[Evaluation of bending strength]

The polarizing plate protective film was cut into 100 mm (TD) x 10 mm (MD), and left for 1 hour under an environment of 23 캜 and 55% RH. Then, This evaluation was measured three times and evaluated as follows. Herein, the collapse of the evaluation means that it is broken and divided into two or more pieces.

◎: No occurrence of breakage in all three times

○: In all three times, there is no occurrence of bending, but the stripe of the bending part is slightly strong

△: At least one of three times, breakage occurred

X: All three times occurred.

The structures of the polarizing plate protective films 101 to 130 and the evaluation results are shown in Table 2 below.

From the results shown in Table 2, it is clear that the polarizing plate protective films 101 to 109 and 113 to 127 of the present invention are excellent in heat resistance, haze, yellow index (YI) and bending resistance. In addition, the polarizing plate protective film 130 to which the rubber particles (compound 2) was not added showed a slight decrease in bending resistance.

In addition, the polarizing plate protective films 126 and 127 produced by the melt-softening method are colored slightly because the yellow index (YI) value is slightly high, and the method of producing the polarizing plate protective film of the present invention is preferably a solution casting method Able to know.

In the comparative polarizing plate protective films 110 to 112, since the blending ratio of the copolymer (B) is high, or only the copolymer (B) is used, the polarizing plate protective films 110 to 112 have poor bending resistance and are difficult to use for practical use. In addition, the polarizing plate protective film 128 using polymethyl methacrylate alone had poor heat resistance and bending resistance.

3. Fabrication of phase difference film

(Production of retardation film A)

The following components were put into a mixing tank and stirred to dissolve each component. The components were then filtered through filter paper having an average pore diameter of 34 탆 and a sintered metal filter having an average pore diameter of 10 탆 to prepare a core layer dope for the following layer, And a dope for the skin A layer were respectively prepared.

(Composition of Dope for Core Layer)

Cellulose acetate (total degree of substitution: 2.45, acetyl group degree of substitution: 2.45, weight average molecular weight: 180,000) 100 parts by mass

Compound C (retardation increasing agent)   3 parts by mass

Compound D (obtained by sealing both ends of a condensate of terephthalic acid / succinic acid / ethanediol / propanediol (80/20/50/50 molar ratio) with an acetyl ester group)   10 parts by mass

Dichloromethane   406 parts by mass

Methanol    61 parts by mass

(3)

(Composition of Dope for Skin B Layer)

Cellulose acetate (total degree of substitution: 2.93, acetyl group degree of substitution: 2.93, weight average molecular weight: 280,000) 100 parts by mass

Compound E (terephthalic acid / succinic acid / ethylene glycol copolymer (50/50/100 molar ratio), molecular weight 2000, retardation agent)   4 parts by mass

Aerosil R972 (manufactured by Nippon Aerosil Co., Ltd., silicon dioxide fine particles (average particle diameter: 15 nm, Matte)  0.12 parts by mass

Citric acid half ethyl ester (exfoliation accelerator, manufactured by Fuso Chemical Industry Co., Ltd.)

    2 parts by mass

Dichloromethane   406 parts by mass

Methanol    61 parts by mass

(Composition of Dope for Skin A Layer)

The composition was the same as that of the dope for the skin B layer except that no partial ethyl ester of citric acid (release promoter) was added.

The resultant dope for the core layer, the dope for the skin A layer and the dope for the skin B layer were jointly opened (simultaneously multilayered) from the flexible die on the running flexible band. Shared streaks were made so that the dope for the skin B layer was in contact with the flexible band. The flexible film was peeled off from the flexible band, and then dried with a tenter to obtain a film-like material. The amount of the residual solvent in the film material immediately after peeling was about 30 mass%. The film-like material was stretched by a tenter in the transverse direction at an elongation of 30% and relaxed at 140 캜 for 60 seconds to obtain a retardation film A having a three-layer structure of a skin B layer / a core layer / a skin layer A .

(Retardation film B)

The following components were put into a mixing tank and stirred to dissolve each component. The components were then filtered through filter paper having an average pore diameter of 34 탆 and a sintered metal filter having an average pore diameter of 10 탆 to prepare a core layer dope for the following layer, And a dope for the skin A layer were respectively prepared.

(Doping for core layer)

Cellulose acetate (total degree of substitution: 2.45, acetyl group degree of substitution: 2.45, weight average molecular weight: 180,000) 100 parts by mass

Compound F (retardation increasing agent)   3 parts by mass

Compound G (succinic acid / adipic acid / ethylene glycol copolymer (copolymerization ratio = 3: 2: 5, molecular weight 2000), retardation reducing agent)   10 parts by mass

Dichloromethane   406 parts by mass

Methanol   61 parts by mass

[Chemical Formula 4]

(Dopant for Skin B layer)

Cellulose acetate (total degree of substitution: 2.93, acetyl group degree of substitution: 2.93, weight average molecular weight: 280,000) 100 parts by mass

Compound E (terephthalic acid / succinic acid / ethylene glycol copolymer (50/50/100 molar ratio), molecular weight 2000, retardation agent)   4 parts by mass

Aerosil R972 (manufactured by Nippon Aerosil Co., Ltd., silicon dioxide fine particles (average particle diameter: 15 nm, Matte) 0.12 parts by mass

N- (2,6-diethylphenylcarbamoylmethyl) iminodiacetic acid (exfoliation accelerator)

         2 parts by mass

Dichloromethane   406 parts by mass

Methanol    61 parts by mass

(Dope for skin A layer)

Except that no N- (2,6-diethylphenylcarbamoylmethyl) iminodiacetic acid (exfoliation promoter) was contained in the preparation of the dope for the skin B layer, and a dope for the skin A layer was obtained .

Layer film having a three-layer structure of skin B layer / core layer / skin A layer was prepared in the same manner as in the production of the above-mentioned retardation film A except that the obtained dope for core layer, the dope for skin A layer and the dope for skin B layer were used. Of the retardation film B was obtained.

(Retardation film C)

The following components were mixed with a dissolver for 50 minutes with stirring, and then dispersed with mannitol diluent to obtain a fine particle dispersion 1.

(Fine particle dispersion 1)

Fine particles (Aerosil R812, manufactured by Nippon Aerosil Co., Ltd.): 11 parts by mass

ethanol 89 parts by mass

To the dissolution tank containing methylene chloride, the prepared fine particle dispersion 1 was slowly added while stirring sufficiently. The resulting solution was dispersed in an attritor so that the particle size of the secondary particles became a predetermined size, and then filtered with Fine Mat NF manufactured by Nippon Seisen Kabushiki Kaisha to prepare a fine particle addition liquid 1.

(Fine particle addition liquid 1)

Methylene chloride 99 parts by mass

Fine Particle Dispersion 1  5 parts by mass

The main doping of the following composition was prepared. First, methylene chloride and ethanol were added to a pressurizing and dissolving tank, and then cellulose acetate having an acetyl group substitution degree of 2.40, a sugar ester compound, a polycondensation ester, a retardation increasing agent and a fine particle addition liquid 1 were added with stirring. This was heated and completely dissolved while stirring. The obtained solution was filtered using Azumi-no. 244 manufactured by Azumi Co., Ltd. to prepare a main dope.

(Composition of main doping)

Methylene chloride 365 parts by mass

ethanol 50 parts by mass

Cellulose acetate (acetyl substitution degree: 2.40, weight average molecular weight: 280,000)

84 parts by mass

Sugar ester 1: sucrose benzoate having an average degree of substitution of 5.5 10 parts by mass

Polycondensation ester: (condensation product of phthalic acid / adipic acid / 1,2-propanediol = 25/75/100 molar ratio at both ends with a benzoate ester group, molecular weight 440)   3 parts by mass

The retardation adjusting agent (compound A)   3 parts by mass

Particle addition liquid 1   1 part by mass

[Chemical Formula 5]

The solvent was evaporated on the stainless steel belt support until the amount of residual solvent in the cast (cast) film was 75%. The obtained film-like material was peeled off from the stainless belt support with a peel tension of 130 N / m. The film-like material obtained by peeling was stretched by 30% in the width direction using a tenter while applying heat at 150 캜. The residual solvent at the start of the stretching was 15%.

Subsequently, drying was completed while conveying the drying zone to a plurality of rolls. The drying temperature was 130 占 폚, and the conveying tension was 100 N / m. Thus, a retardation film (C) having a dried film thickness of 35 mu m was obtained.

4. Production of Polarizer

(Production of polarizing plate 101P and polarizing plate 101U)

1) Production of polarizer

A polyvinyl alcohol film having a thickness of 30 占 퐉 was swelled with water at 35 占 폚. The obtained film was immersed in an aqueous solution containing 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds and immersed in an aqueous solution at 45 캜 containing 3 g of potassium iodide, 7.5 g of boric acid and 100 g of water. The obtained film was uniaxially stretched under the conditions of a stretching temperature of 55 캜 and a draw ratio of 2. The uniaxially stretched film was washed with water and then dried to obtain a polarizer having a thickness of 15 mu m. Similarly, the stretching magnification was changed to produce a polarizer having a thickness of 10 mu m.

2) Preparation of water pollen

As a completely saponified polyvinyl alcohol adhesive, a 3% aqueous solution of polyvinyl alcohol (PVA-117H manufactured by Kurara) was prepared.

3) Preparation of active energy ray-curable adhesive liquid

The following components were mixed and defoamed to prepare an active energy ray curable adhesive liquid. Further, triarylsulfonium hexafluorophosphate was formulated as a 50% propylene carbonate solution, and the solid content of triarylsulfonium hexafluorophosphate was shown below.

3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate    45 parts by mass

40 parts by mass of Polyd GT-301 (alicyclic epoxy resin manufactured by Daicel Chemical Industries, Ltd.)

1,4-butanediol diglycidyl ether    15 parts by mass

Triarylsulfonium hexafluorophosphate   2.3 parts by mass

9,10-dibutoxyanthracene         0.1 parts by mass

1,4-diethoxynaphthalene   2.0 parts by mass

4) Production of polarizer

First, the retardation film (C) was prepared as a retardation film, and its surface was subjected to a corona discharge treatment. The conditions of the corona discharge treatment were a corona output power of 2.0 kW and a line speed of 18 m / min. Subsequently, the water-borne or active energy ray-curable adhesive liquid prepared above was coated on the corona discharge treated surface of the retardation film (C) by a bar coater so as to have a film thickness after curing of about 3 mu m, Thereby forming a curable adhesive layer. The thus-prepared water-soluble or active energy ray-curable adhesive layer was bonded with a polarizer having a thickness of 15 탆 as described above.

Subsequently, a polarizing plate protective film 101 was prepared as a polarizing plate protective film, and the surface of the polarizing plate protective film 101 was corona discharge treated. The conditions of the corona discharge treatment were a corona output power of 2.0 kW and a line speed of 18 m / min. Subsequently, the water-borne or active energy ray-curable adhesive liquid prepared above was coated on the corona discharge treated surface of the polarizing plate protective film 101 with a bar coater so as to have a film thickness of about 3 mu m after curing, Thereby forming a curable adhesive layer.

A polarizer bonded to one side of the retardation film (C) is bonded to the water-repellent layer of the polarizing plate protective film or the active energy ray-curable adhesive layer to form a laminate of the polarizing plate protective film 101, the watery / polarizer / Polarizing plate 101P. The obtained polarizing plate 101P was dried at 80 占 폚.

The laminate was formed so that the slow axis of the retardation film (C) and the absorption axis of the polarizer were orthogonal to each other.

Similarly, a polarizing plate 101U as a laminate of the polarizing plate protective film 101 / active energy ray curable adhesive layer / polarizer / active energy ray curable adhesive layer / retardation film (C) was obtained.

Polarizing plate 101U is, from the phase difference film (C) side, the belt conveyor equipped with an ultraviolet irradiation apparatus using a (lamp, using a D-bulb of a Fusion UV Systems, Inc.), the accumulated light quantity is irradiated with ultraviolet rays so that 750mJ / cm ² , And the active energy ray-curable adhesive layer was cured.

(Production of polarizing plates 102P to 130P and 102U to 130U)

Except that polarizers (10 탆 and 15 탆 in thickness), polarizing plate protective films 102 to 130, and retardation films A, B and C were combined as described in Table 3 in the preparation of the polarizing plate 101P and the polarizing plate 101U , And polarizers 102P to 130P and 102U to 130U were produced.

The interfacial adhesion of the polarizing plate protective film / polarizer thus obtained was evaluated by the following methods, and the results are shown in Table 3 together.

(4) Adhesiveness

Each prepared polarizing plate was cut into a square having a size of 50 mm x 50 mm and allowed to stand for 24 hours under an atmosphere of 23 ° C and 55% RH. Then, the polarizing plate was peeled from the edge portion at the interface between the polarizer and the protective film. This operation was evaluated with respect to each of the polarizing plates, and whether or not peeling occurred between the polarizer and the protective film was visually observed, and the adhesiveness was evaluated according to the following criteria.

&Amp; cir &amp;: no peeling occurred at all over the entire surface

O: Film peeling occurred almost over the entire surface

?: Part of the four corners of the polarizer shows extremely weak peeling, but practically acceptable quality

X: Clear film peeling occurred, which is a problematic quality in practical use

5. Fabrication of Liquid Crystal Display

As a liquid crystal cell, a VA type liquid crystal cell having two glass substrates with a thickness of 0.5 mm and a liquid crystal layer disposed therebetween was prepared. The prepared polarizing plates 101U were bonded to both surfaces of the liquid crystal cell prepared above via a double-faced tape (inorganic tape MO-3005C) of 25 m in thickness manufactured by Lintec Corp. to obtain a liquid crystal display panel. The bonding was performed so that the retardation film (C) of the polarizing plate 101U was in contact with the glass substrate of the liquid crystal cell.

Then, the liquid crystal display panel (laminate of viewer-side polarizing plate / liquid crystal cell / backlight side polarizing plate) was removed from a 40-inch display BRAVIA KLV-40J3000 (VA system) manufactured by SONY, The display device 101 was obtained. The absorption axis of the polarizing plate of the installed liquid crystal display panel was set in the same direction as the absorption axis of the polarizing plate attached in advance.

Similarly, the liquid crystal display devices 102 to 130 were produced using the polarizing plates 102U to 130U.

Bend unevenness of the obtained liquid crystal display device was measured by the following method.

(Bend unevenness)

The prepared liquid crystal display was allowed to stand under the environment of 40 캜 and 95% RH for 24 hours. Subsequently, the difference between the luminance near the four vertexes of the display screen and the luminance near the central portion of the display screen (image unevenness with respect to the central portion and the peripheral portion) was visually observed in a black display state of the liquid crystal display device under an environment of 40 캜 dry .

Then, bend unevenness was evaluated based on the following criteria.

○: No bend unevenness appears at all

B: Bend unevenness slightly appears, but practically acceptable quality is acceptable.

X: Apparent bend unevenness appears

The structures of the polarizers 101P to 128P and the polarizers 101U to 128U and the evaluation results are collectively shown in Table 3 below.

From the results shown in Table 3, it can be seen that the polarizing plate protective films 101 to 109 and 113 to 127, 129, and 130 of the present invention are excellent in adhesiveness to polarizers of the water-soluble and active energy ray- have. It is also clear that the polarizing plate in which the polarizer is sandwiched between the polarizing plate protective film and the cellulose ester type retardation film of the present invention is excellent in bend unevenness when provided in a liquid crystal display device.

From the results of the above Tables 2 and 3, it can be seen that the polarizing plate protective film of the present invention has a high water resistance and suppresses occurrence of bend unevenness of the liquid crystal display device, It was found that an excellent excellent polarizing plate protective film having good adhesion with a polarizer can be obtained even in combination.

[Industrial applicability]

The polarizing plate protective film of the present invention has a high water resistance and heat resistance and suppresses the occurrence of bend unevenness of the liquid crystal display device and also exhibits good adhesion with polarizers in combination with water- Therefore, it is suitably used for a polarizing plate and a liquid crystal display device.

1: melting furnace 3, 6, 12, 15: filter
4, 13: Storage tank 5, 14: Pump pump
8, 16: conduit 10: ultraviolet absorber input kiln
20: confluent tube 21: mixer
30: die 31: metal support
32: Web 33: Peeling position
34: tenter device 35: roller drying device
41: Feeding kiln 42: Stock kiln
43: Pump 44: Filter
101: polarizer 102: polarizer protective film
103A and 103B: an active energy ray-curable adhesive layer
104: polarizer 105: phase difference film
106: liquid crystal display device 107: liquid crystal cell

Claims (15)

(A) obtained by polymerizing an aromatic vinyl monomer and an unsaturated nitrile monomer as a main component of a thermoplastic resin and a copolymer (B) having an imide ring structure in a mass ratio of A: B = 100: 0 to 50:50 Wherein the polarizer protective film is contained in a range of from 0.1 to 10% by mass. The method according to claim 1,
Wherein the copolymer (A) obtained by polymerizing the aromatic vinyl monomer and the unsaturated nitrile monomer contains an aromatic vinyl monomer unit in an amount of 50 to 75 mol% and an unsaturated nitrile monomer unit in a ratio of 25 to 50 mol% Wherein the polarizer protective film is a polarizer protective film. 3. The method according to claim 1 or 2,
Wherein the aromatic vinyl monomer is styrene, and the unsaturated nitrile monomer is acrylonitrile. 4. The method according to any one of claims 1 to 3,
Wherein the imide ring structure is a maleimide structure or a glutarimide structure. 5. The method according to any one of claims 1 to 4,
Further, at least one of an acid, an alcohol, a metal salt, a nonionic surfactant or a non-reactive quaternary ammonium salt type surfactant having a linear or branched alkyl group having 8 to 22 carbon atoms is added to the copolymer (A) and the (B) in the range of 0.1 to 1.0 mass% with respect to the total mass of the polarizing plate protective film. 6. The method according to any one of claims 1 to 5,
The polarizing plate protective film further comprises at least one of a core-shell type acrylic fine particle, a styrene-conjugated dienic compound or a butyl acrylate-based compound. 7. The method according to any one of claims 1 to 6,
Wherein the aromatic vinyl monomer and the unreacted monomer of the unsaturated nitrile monomer contained in the copolymer (A) are each 0.1 mass% or less based on the total mass of the copolymer (A). 8. The method according to any one of claims 1 to 7,
A haze of 1.0% or less, and a yellow index (YI) of 1.0 or less. 9. The method according to any one of claims 1 to 8,
Wherein the polarizing plate protective film can be bonded to the polyvinyl alcohol polarizer using any of a polyvinyl alcohol adhesive or an active energy ray curable adhesive. A process for producing a polarizing plate protective film for producing the polarizing plate protective film according to any one of claims 1 to 9, wherein the polarizing plate protective film is produced by a solution casting method. A polarizing plate characterized in that the polarizing plate protective film according to any one of claims 1 to 9 and a polarizer are bonded by using a polyvinyl alcohol-based adhesive. A polarizing plate characterized in that the polarizing plate protective film according to any one of claims 1 to 9 and a polarizer are bonded to each other using an active energy ray curable adhesive. 13. The method according to claim 11 or 12,
A polarizing plate characterized in that the polarizing plate protective film on the opposite side between the polarizing plate protective film and the polarizer according to any one of claims 1 to 9 is a cellulose ester film. 14. The method according to any one of claims 11 to 13,
Wherein the double-sided adhesive of the polarizer is the same type of adhesive. A liquid crystal display device characterized in that the polarizing plate protective film according to any one of claims 1 to 9 is arranged on the viewer side of the viewer side polarizing plate and the backlight side of the backlight side polarizing plate.

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