JP6776553B2 - Polarizing plate protective film - Google Patents

Description

The present invention relates to a polarizing plate protective film, and more particularly to a thin polarizing plate protective film having excellent scratch resistance and winding shape when a long-shaped polarizing plate protective film is wound as a roll.

In order to reduce the thickness of the polarizing plate, a thinner polarizing plate protective film is required.

In particular, from the viewpoint of the durability of the polarizing plate, the use of a polarizing plate protective film made of norbornene-based resin is increasing.

However, since the rigidity of a polarizing plate protective film using a norbornene-based resin having a thickness of 10 μm or less is lowered, there is a problem that when a long film is wound as a roll, scratches due to the winding are likely to occur. It was.

Further, the polarizing plate protective film using the norbornene-based resin having a film thickness of 10 μm or less has a problem that the winding shape is deformed when the roll body is formed.

On the other hand, as a method for producing a thin-film polarizing plate protective film, Patent Document 1 discloses a method for forming a cycloolefin-based polymer film with a thin film by applying a cycloolefin-based polymer on a temporary support to form a film. ing.

However, even this method is insufficient to solve the problems of scratch resistance and deformation of the wound shape when the long film is made into a roll.

International Publication No. 2014/199934

The present invention has been made in view of the above problems and situations, and the problem to be solved is a thin film having excellent scratch resistance and winding shape when a long polarizing plate protective film is wound as a roll body. It is to provide a polarizing plate protective film.

In the process of examining the cause of the above problem in order to solve the above problems, the present inventor has a thin film containing a norbornene-based resin having a specific norbornan skeleton, a silicone-based additive, and a residual solvent on the support. The polarizing plate protective film having a polymer layer and the polymer layer having a specific retardation value reduces the occurrence of scratches when the thin and long polarizing plate protective film is wound as a roll. It has been found that a polarizing plate protective film having an excellent winding shape can be obtained.

That is, the above problem according to the present invention is solved by the following means.

1. 1. A polarizing plate protective film obtained by winding a long film having a polymer layer containing a norbornene resin on a support as a roll.
The layer thickness of the polymer layer is in the range of 1 to 10 μm.
The norbornene-based resin is a norbornene-based resin having a norbornane skeleton represented by the following general formula (1).
The retardation value Ro defined by the following formula (i) of the polymer layer is in the range of 0 to 10 nm, and the retardation value Rt defined by the following formula (ii) is in the range of -20 to 20 nm. And
The polymer layer contains a silicone-based additive in the range of 0.01 to 5.0% by mass with respect to all the components excluding the solvent in the material constituting the polymer layer, and
A polarizing plate protective film, wherein the polymer layer contains a residual solvent containing an aromatic solvent, and the mass of the residual solvent is in the range of 500 to 10000 ppm.

〔式中、Ｒは、炭素数が１〜３の直鎖又は分岐アルキル基を表す。〕
式（ｉ）
Ｒｏ＝（ｎ_ｘ−ｎ_ｙ）×ｄ
式（ii）
Ｒｔ＝｛（ｎ_ｘ＋ｎ_ｙ）／２−ｎ_ｚ｝×ｄ
〔式中、Ｒｏはポリマー層の面内方向のリターデーション値、Ｒｔはポリマー層の厚さ方向のリターデーション値、ｎ_ｘはポリマー層の遅相軸方向の屈折率、ｎ_ｙはポリマー層の面内の進相軸方向の屈折率、ｎ_ｚはポリマー層の厚さ方向の屈折率（屈折率は２３℃、５５％ＲＨの環境下、波長５９０ｎｍで測定）、ｄはポリマー層の厚さ（ｎｍ）を表す。〕
２．前記ポリマー層が、マット剤を当該ポリマー層全質量の０．１〜０．５質量％の範囲内で含有することを特徴とする第１項に記載の偏光板保護フィルム。

[In the formula, R represents a linear or branched alkyl group having 1 to 3 carbon atoms. ]
Equation (i)
Ro = (n _{x −} n _y ) × d
Equation (ii)
Rt = {(n _x + n _y ) /2- _nz } × d
Wherein, Ro-plane direction of the retardation value of the polymer layer, Rt is the thickness direction of the retardation value of the polymer layer, n _x is a refractive index in a slow axis direction of the polymer layer, n _y is the polymer layer In-plane refractive index in the phase-advancing axis direction, _nz is the refractive index in the thickness direction of the polymer layer (refractive index is measured at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH), and d is the thickness of the polymer layer. Represents (nm). ]
2. The polarizing plate protective film according to Item 1, wherein the polymer layer contains a matting agent in the range of 0.1 to 0.5% by mass of the total mass of the polymer layer.

3. 3. The polarizing plate protective film according to Item 2, wherein the matting agent is silica particles, and the silica particles have a mixing ratio of methanol of 45% by volume or more in a hydrophobicity test by a methanol wettability method. ..

4. The polarizing plate protective film according to any one of items 1 to 3, wherein the polymer layer further contains a polyester-based plasticizer.

5 . The polarizing plate protective film according to any one of items 1 to 4 , wherein the support is a polyester resin film.

According to the above means of the present invention, it is possible to provide a thin polarizing plate protective film having excellent scratch resistance and winding shape when a long polarizing plate protective film is wound as a roll body.

Although the mechanism of expression or mechanism of action of the effects of the present invention has not been clarified, it is inferred as follows.

In the present invention, a thin polymer layer containing a norbornene-based resin having a specific structure is integrated with a support to form a polarizing plate protective film, whereby scratches when the polarizing plate protective film is wound as a roll body. Can be suppressed. It is presumed that this is because the rigidity of the polymer layer is increased by the norbornene-based resin having a specific structure, and the rigidity of the film is increased by integrating with the support, so that the occurrence of scratches is suppressed. ..

Further, by incorporating the silicone-based additive in the polymer layer containing the norbornene-based resin, it is possible to suppress the deformation of the wound shape when the long polarizing plate protective film is made into a roll. It is presumed that the norbornene-based resin film containing the silicone-based additive can suppress the deformation of the wound shape because the squeak value is lowered by the action of the silicone.

Further, the inclusion of the matting agent improves the slipperiness of the surface and lowers the squeak value, so that the occurrence of scratches and the deformation of the wound shape can be further suppressed.

As the support according to the present invention, it is preferable to use a polyester resin film. Since the polyester resin film has good flatness, when it is used as a support, the flatness of the polarizing plate protective film is improved, and the deformation of the winding shape can be further suppressed.

Further, the use of a polyester plasticizer and an aromatic solvent has an effect of reducing the retardation value, and is suitable as a polarizing plate protective film having a low retardation value and as a retardation film for an IPS type liquid crystal display device. Is.

Schematic diagram showing the structure of the polarizing plate protective film of the present invention Schematic diagram of a coating apparatus for producing the polarizing plate protective film of the present invention

The polarizing plate protective film of the present invention is a polarizing plate protective film obtained by winding a long film having a polymer layer containing a norbornene-based resin on a support as a roll, and the layer thickness of the polymer layer is high. The norbornene-based resin in the range of 1 to 10 μm is a norbornene-based resin having a norbornene skeleton represented by the general formula (1), and the retardation defined by the formula (i) of the polymer layer. The value Ro is in the range of 0 to 10 nm, the retardation value Rt defined by the above formula (ii) is in the range of -20 to 20 nm, and the polymer layer is a material constituting the polymer layer. A silicone-based additive in the range of 0.01 to 5.0% by mass is contained with respect to all the components except the solvent inside, and the polymer layer contains a residual solvent containing an aromatic solvent. The residual solvent mass is in the range of 500 to 10000 ppm. This feature is a technical feature common to or corresponding to the invention according to each claim.

As an embodiment of the present invention, from the viewpoint of exhibiting the effect of the present invention, it is preferable that the polymer layer contains the matting agent within the range of 0.1 to 0.5% by mass of the total mass of the polymer layer. When the matting agent is silica particles and the silica particles have a methanol mixing ratio of 45% by mass or more in a hydrophobicity test by the methanol wettability method, the effect of reducing the squeak value of the film is high. Deformation of the winding shape of the roll body of the polarizing plate protective film can be further suppressed, which is preferable.

Further, when the polymer layer further contains a polyester-based plasticizer and the residual solvent contains an aromatic solvent, the effect of lowering the retardation value is exhibited, and the IPS type liquid crystal display device can be used. This is a preferred embodiment as the polarizing plate protective film to be used.

From the viewpoint of flatness, it is preferable that the support is a polyester resin film.
By using it as the support according to the present invention, it is possible to further suppress the deformation of the rolled shape of the roll body of the polarizing plate protective film, which is preferable.

Hereinafter, the present invention, its constituent elements, and modes and modes for carrying out the present invention will be described in detail. In the present application, "~" is used to mean that the numerical values described before and after the value are included as the lower limit value and the upper limit value.

<< Outline of the polarizing plate protective film of the present invention >>
The polarizing plate protective film of the present invention is a polarizing plate protective film obtained by winding a long film having a polymer layer containing a norbornene-based resin on a support as a roll, and the layer thickness of the polymer layer is high. The norbornene-based resin in the range of 1 to 10 μm is a norbornene-based resin having a norbornene skeleton represented by the following general formula (1), and the retardation defined by the following formula (i) of the polymer layer. The value Ro is in the range of 0 to 10 nm, the retardation value Rt defined by the following formula (ii) is in the range of -20 to 20 nm, and the polymer layer is a material constituting the polymer layer. A silicone-based additive in the range of 0.01 to 5.0% by mass is contained with respect to all the components except the solvent inside, and the polymer layer contains a residual solvent containing an aromatic solvent. The residual solvent mass is in the range of 500 to 10000 ppm.

The residual solvent contained in the cycloolefin-based film of the present invention refers to the mass of the solvent contained in the film after the film is produced. The solvent mass can be quantified by the head space gas chromatography method described later, and the measurement is a value measured in the period from the film production to the film processing. Normally, the film is manufactured, wound up, wrapped in a protective sheet or the like, stored in a semi-sealed state, and is in that state until it is processed, so that the amount of residual solvent fluctuates little. Therefore, it can be determined whether or not the amount of the residual solvent is the constitution of the present invention based on the value measured in the period from the film production to the film processing.

Protective film for polarizing plate of the present invention, Ri elongated der, specifically, it is preferably a length of about 100～10000M, more preferably from approximately 3000～10000M, into a roll Take up. The width of the polarizing plate protective film of the present invention is preferably 1 m or more, more preferably 1.3 m or more, and particularly preferably 1.3 to 4 m.

The structure of the polarizing plate protective film of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view showing an example of the polarizing plate protective film of the present invention.

The polarizing plate protective film F of the present invention has a configuration in which a polymer layer 2 containing a norbornene-based resin is provided on a support 1. The polymer layer 2 is preferably formed by applying a coating composition containing a norbornene-based resin onto the support 1. Further, as an embodiment of the present invention, a composition containing a norbornene-based resin is cast on a metal support, then peeled off to form a film, and the film is adhered to the support as a polymer layer according to the present invention. Although it also includes an embodiment of integration, it is usually difficult to uniformly produce a thin film of about 1 to 10 μm without any trouble such as breakage. Therefore, a coating composition containing a norbornene-based resin is applied on the support 1. It is preferable to adopt the method of forming the polymer layer 2 by applying to.

A blocking prevention layer, a curl prevention layer, or the like can be provided on the surface of the support 1 opposite to the polymer layer, and a functional layer such as a hard coat layer or an optical compensation layer can be provided on the polymer layer. Can be provided as appropriate.

Hereinafter, the components of the present invention will be described in detail.

[1] Norbornene-based resin having a norbornane skeleton represented by the general formula (1) The polarizing plate protective film of the present invention is a norbornene-based resin having a norbornane skeleton represented by the following general formula (1) as a film constituent material. It is characterized by containing.

In the above general formula (1), R represents a linear or branched alkyl group having 1 to 3 carbon atoms. Specific examples represent a methyl group, an ethyl group, an n-propyl group, or an i-propyl group.

The preferable molecular weight of the norbornene-based resin having a norbornane skeleton represented by the general formula (1) according to the present invention is within the range of 0.2 to ⁵ cm ³ / g in intrinsic viscosity [η] inh measured at 30 ° C. It is preferably in the range of 0.3 to ³ cm ³ / g, and particularly preferably in the range of 0.4 to 1.5 cm ³ / g.

The number average molecular weight (Mn) is in the range of 8,000 to 100,000, more preferably in the range of 1,000 to 80,000, and particularly preferably in the range of 12,000 to 50,000.

The weight average molecular weight (Mw) is preferably in the range of 100,000 to 180,000, and more preferably in the range of 11,000 to 140000.

When the intrinsic viscosity [η] inh, number average molecular weight (Mn) and weight average molecular weight (Mw) are within the above ranges, the heat resistance and water resistance of the norbornene-based resin having a norbornane skeleton represented by the general formula (1). The properties, chemical resistance, mechanical properties, and moldability of the polarizing plate protective film of the present invention are improved.

The intrinsic viscosity [η] inh is measured by using a Ubbelohde viscometer (measurement temperature: 30 ° C.) for a resin solution in which a norbornene-based resin having a norbornane skeleton represented by the general formula (1) is dissolved in chloroform. Can be done.

The number average molecular weight (Mn) and weight average molecular weight (Mw) are gel permeation chromatography (HLC8220GPC manufactured by Tosoh Corporation) and column (TSK-GEL G6000HXL-G5000HXL-G5000HXL-G4000HXL-G3000HXL manufactured by Tosoh Corporation.
In series) is used for measurement. 20 mg ± 0.5 mg of the sample is dissolved in 10 mL of tetrahydrofuran and filtered through a 0.45 mm filter. 100 mL of this solution is injected into a column (temperature 40 ° C.), measured at a detector RI temperature of 40 ° C., and a styrene-converted value is used.

[2] Silicone-based additive Examples of the silicone-based additive include a silicone-based surfactant and the like. Here, the silicone-based additive means an oligomer or polymer having a siloxane skeleton as a repeating unit, and this siloxane repeating structure may have a main chain or a grafted side chain. You may do it.

Examples of the silicone-based surfactant include polyether-modified silicone and acrylic-modified silicone, and the GL series manufactured by Kyoeisha Chemical Co., Ltd. (for example, GL-01, GL-02R, GL-03, GL-) can be mentioned. 04R, etc.) and the Silface series manufactured by Nisshin Kagaku Kogyo Co., Ltd. (for example, Silface SAG002, Silface SAG005, Silface SAG008, Silface SAG503A, etc.) and the like.

The content of the silicone-based additive, the total components except solvent in the material constituting the polymer layer is in the range of 0.01 to 5.0 mass%, 0.05 to 3.0 wt% The range of is more preferable. When the content is 0.01% by mass or more, the effect of the present invention can be sufficiently exhibited, and when it is 5.0% by mass or less, the haze of the polymer layer is suppressed to a low level and the slipperiness is more reliably performed. Can be granted.

Further, as long as the effects of the present invention are not impaired, for example, a fluorine-based material such as a fluorine-based surfactant, a fluorine-siloxane graft compound or a fluorine-based compound, for example, a vinyl-based material such as a vinyl copolymer or a vinyl-siloxane graft compound. A material, for example, an acrylic material such as an acrylic-silicone graft compound or an acrylic copolymer can be appropriately used as a surface conditioner.

[3] Matting agent The polymer layer according to the present invention preferably contains a matting agent.

The matting agent applicable to the polymer layer according to the present invention is usually used as an additive for a film, and it is effective to impart irregularities to the surface of the polymer layer in order to improve the poor slipperiness of the surface. It is used to increase the roughness of the surface of the polymer layer by containing organic fine particles or inorganic fine particles to make it so-called matte, thereby reducing the adhesiveness and improving the scratch resistance. ..

However, the rougher the surface, the higher the haze and the lower the transparency, so that the average particle size and content of the applicable matting agent are limited. The matting agent used in the present invention preferably has an average particle size in the range of 1 to 1000 nm, more preferably in the range of 1 to 100 nm, and particularly preferably in the range of 3 to 500 nm.

<Measuring method of average particle size of matting agent>
The measurement of the particle size of the matting agent in the polymer layer according to the present invention is included in a tomographic cut photograph obtained by photographing a layer cross section tomographically cut with a microtome with a scanning electron microscope (SEM) at an appropriate magnification. The particle size of 100 particles is measured, and the average value is calculated and used as the average particle size. When the cross section of the particle is circular, the particle diameter is the diameter, and when the cross section is not circular, the area is calculated and converted to the circular shape.

SEM: JSM-6060LA (JEOL Ltd.)
Microtome: Leica EM UC6
The amount of the matting agent added is 0.1 to 0.5% by mass with respect to 100% by mass of the film from the viewpoint of balancing the slippery effect and haze regardless of whether it is spherical or amorphous fine particles. It is preferably within the range.

In the present invention, the haze value of the polymer layer containing the matting agent is 2.0% or less, more preferably 1.2% or less, and particularly preferably 0.5% or less.

The coefficient of static friction of the polymer layer to which the matting agent is added is 1.5 or less, and 1.0 or less is particularly preferable. The coefficient of dynamic friction can be measured according to "JIS K7125 Plastic-Film and Sheet Friction Coefficient Test Method".

When the static friction coefficient is 1.5 or less, the polarizing plate protective film having the polymer layer does not cause creases or wrinkles during winding, and therefore the creases or creases impair the winding shape, or the creases or wrinkles Non-uniform tension is not applied to the polarizing plate protective film, and there is no problem that unintended non-uniform optical characteristics are exhibited on the film surface.

The matting agent applicable in the present invention is not particularly limited as long as it is used for a general polarizing plate protective film, and two or more kinds of these matting agents can be mixed and used. Examples of the matting agent according to the present invention include inorganic fine particles and organic fine particles containing a polymer compound.

Examples of the inorganic fine particles include inorganic fine particles such as barium sulfate, manganese colloid, titanium dioxide, strontium sulfate barium sulfate, and silicon dioxide. Further, for example, synthetic silica obtained by a wet method or gelation of silicic acid and the like. Examples thereof include silicon dioxide and titanium dioxide produced by titanium slug and sulfuric acid (rutile type and anatas type). As the inorganic fine particles, those containing silicon are preferable because they can reduce turbidity and haze of the film. Many of the fine particles such as silicon dioxide are surface-modified with an organic substance, but such fine particles are preferable because they can reduce the surface haze of the film. Preferred organic substances for surface modification include halosilanes, alkoxysilanes, silazane, and siloxane.

Further, examples of the polymer compound constituting the organic fine particles include polytetrafluoroethylene, cellulose acetate, polystyrene, polymethyl methacrylate, polypropyl methacrylate, polymethyl acrylate, polyethylene carbonate, starch and the like, and pulverized grades thereof. Can also be mentioned. Alternatively, a polymer compound synthesized by a suspension polymerization method, a polymer compound made spherical by a spray-drying method, a dispersion method, or the like, or an inorganic compound can be used.

Among the above matting agents, silicon dioxide particles (silica particles) are preferable.

In particular, the silica particles are surface-modified with at least one compound selected from alkylsilanes having an alkyl group having 4 to 21 carbon atoms, dimethylsiloxane, dimethylsiloxane cyclic bodies, methacryloxysilanes, and aminosilanes. Is preferable.

By containing silica particles whose surface is modified with a compound having such a long-chain functional group or a cyclic functional group, entanglement and interaction with the norbornene-based resin are improved, and secondary aggregates are easily formed. By doing so, the matte effect of the norbornene-based resin film itself is exhibited.

Further, it is preferable that the surface of the silica particles is hydrophobized because the dispersibility in the solvent is good and the generation of foreign substances can be suppressed.

The degree of hydrophobization of the surface of silica particles can be quantified by the following methanol wettability method.

<Methanol wettability method>
In a mixed solution of methanol and pure water, the same amount (same volume) of silica particles is added to each solution while changing the mixing ratio of methanol to pure water, and the mixture is stirred and mixed, and each of the mixed solutions is centrifuged. The volume of the sediment of the silica particles is determined by separating them, and the mixture ratio of methanol in the solution in which the volume of the sediment of the silica particles in the solution is 50%.

When the mixing ratio of methanol is 45% by volume or more, it can be said that the silica particles are preferable for the present invention.

For example, a plurality of solutions in which the mixing ratio of methanol to pure water is changed are prepared, and the volume of the sediment of silica fine particles to be measured is 2.5 mL, and the volume of the silica particles added first is 5 mL. When the ratio is 45% by volume or more, the silica particles can be said to be hydrophobized silica particles having surface modification preferable to the present invention.

As the silica particles according to the present invention, commercially available products can be preferably used, and the following product Aerosil series of Nippon Aerosil Co., Ltd. is suitable (the surface modifiers in parentheses).

R812 (trimethylsilane), R805 (octylsilane), R816 (hexadecylsilane), NKC130 (dimethylsiloxane), R711, R7200 (above, methacryloxysilane), R202, RY200, RY200S, RY300 (above, dimethylsiloxane), It is commercially available under the trade names of R104, R105 (above, dimethylsiloxane cyclic body), RA200H, RA200HS (above, aminosilane) (above, hydrophobic Aerosil manufactured by Nippon Aerosil Co., Ltd.) and can be used.

Among these, Aerosil R812, R805, R816, NKC130, and RY300 are preferable because they can improve the handleability at the time of handling and keep the haze of the polymer layer low.

(Organic solvent used for matting agent dispersion)
The matting agent is preferably dispersed in an organic solvent and added to the coating composition of the polymer layer.

The organic solvent used in the preparation of the matting agent dispersion is not particularly limited as long as the matting agent is dispersed and the dispersion can be prepared. The organic solvent used in the present invention is, for example, a solvent selected from chlorine-based solvents such as dichloromethane and chloroform, chain hydrocarbons having 3 to 12 carbon atoms, cyclic hydrocarbons, aromatic hydrocarbons, esters, ketones, and ethers. Is preferable. Esters, ketones and ethers may have a cyclic structure.

In the present invention, as the organic solvent used in the method for preparing the matting agent dispersion liquid, one kind of organic solvent may be used alone, or two or more kinds of organic solvents may be mixed and used in an arbitrary ratio.

When the above-mentioned matting agent is dispersed, if the amount of the above-mentioned organic solvent is small, sufficient dispersion cannot be performed, aggregates are generated, and it causes a foreign matter failure. On the contrary, when the amount of the organic solvent is large, the dispersibility of the fine particles is excellent, but a large amount of the dispersion liquid is prepared, which is not preferable in terms of handling in production. Therefore, the amount of the organic solvent used is preferably in the range of 1000 to 100,000 parts by mass, more preferably in the range of 1500 to 40,000 parts by mass, and 2000 to 40,000 parts by mass with respect to 100 parts by mass of the matting agent. It is particularly preferably within the range of 20000 parts by mass.

[4] Polyester-based plasticizer In the polarizing plate protective film of the present invention, applying a polyester-based plasticizer to the polymer layer has the effect of reducing the retardation value, as well as the film elastic modulus, slipperiness, and film. It is preferable in that the film surface hardness is improved, and as a result, high-quality surface quality can be obtained.

The polyester-based plasticizer has a structure represented by the following general formula (2).

General formula (2)
B- (GA) _n -GB
In the above general formula (2), B represents a group derived from a hydroxy group-containing monocarboxylic acid having a ring structure. The ring structure refers to a structure having an aliphatic hydrocarbon ring, an aliphatic hetero ring, an aromatic hydrocarbon ring or an aromatic hetero ring, and preferably a structure having an aliphatic hydrocarbon ring or an aromatic hydrocarbon ring. .. The hydroxy group-containing monocarboxylic acid having a ring structure can be an alicyclic monocarboxylic acid having 5 to 20 carbon atoms, an aromatic monocarboxylic acid having 7 to 20 carbon atoms, or a mixture thereof.

The alicyclic monocarboxylic acid having 5 to 20 carbon atoms can be preferably an alicyclic monocarboxylic acid having 6 to 15 carbon atoms. Examples of alicyclic monocarboxylic acids include 4-hydroxycyclohexylacetic acid, 3-hydroxycyclohexylacetic acid, 2-hydroxycyclohexylacetic acid, 4-hydroxycyclohexylpropionic acid, 4-hydroxycyclohexylbutyric acid, 4-hydroxycyclohexylglycolic acid, 4 -Hydroxy-o-methylcyclohexylacetic acid, 4-hydroxy-m-methylcyclohexylacetic acid, 4-hydroxy-p-methylcyclohexylacetic acid, 5-hydroxy-m-methylcyclohexylacetic acid, 6-hydroxy-o-methylcyclohexylacetic acid, 2 , 4-Dihydroxycyclohexylacetic acid, 2,5-dihydroxycyclohexylacetic acid, 2- (hydroxymethyl) cyclohexylacetic acid, 3- (hydroxymethyl)cyclohexylacetic acid, 4- (hydroxymethyl)cyclohexylacetic acid, 2- (1-hydroxy-1) -Methylethyl) cyclohexyl acetic acid, 3- (1-hydroxy-1-methylethyl) cyclohexyl acetic acid, 4- (1-hydroxy-1-methylethyl) cyclohexyl acetic acid and the like are included.

The aromatic monocarboxylic acid having 7 to 20 carbon atoms can be preferably an aromatic monocarboxylic acid having 7 to 15 carbon atoms. Examples of aromatic monocarboxylic acids include 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 2-hydroxybenzoic acid, 4-hydroxy-o-toluic acid, 3-hydroxy-p-toluic acid, 5-hydroxy-. m-toluic acid, 6-hydroxy-o-toluic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 2- (hydroxymethyl) benzoic acid, 3- (hydroxymethyl) benzoic acid, 4- (Hydroxymethyl) benzoic acid, 2- (1-hydroxy-1-methylethyl) benzoic acid, 3- (1-hydroxy-1-methylethyl) benzoic acid, 4- (1-hydroxy-1-methylethyl) benzoic acid Contains acids and the like.

Among these, a hydroxy group-containing monocarboxylic acid containing an aromatic ring (aromatic monocarboxylic acid containing a hydroxy group) is provided with sufficient hydrophobicity to the polarizing plate protective film and easily suppresses deterioration of the polarizer due to moisture. ) Is preferable.

In the formula, G is a group consisting of an alkylene diol having 2 to 12 carbon atoms, a cycloalkylene diol having 6 to 12 carbon atoms, an oxyalkylene diol having 4 to 12 carbon atoms, and an arylene diol having 6 to 12 carbon atoms. Represents a group derived from at least one selected from.

Examples of alkylene diols having 2 to 12 carbon atoms include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,2-propane. Diol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2,2-diol -1,3-Propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3propanediol (3,3-dimethylolheptan), 3-Methyl-1,5- Pentandiol 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9- Nonandiol, 1,10-decanediol, 1,12-octadecanediol and the like are included.

Examples of cycloalkylene diols having 6 to 12 carbon atoms include hydrogenated bisphenol A (2,2-bis (4-hydroxycyclohexyl) propane) and hydrogenated bisphenol B (2,2-bis (4-hydroxycyclohexyl)). Butan etc. are included.

Examples of oxyalkylene diols having 4 to 12 carbon atoms include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol and the like.

Examples of arylene diols having 6 to 12 carbon atoms include bisphenol A, bisphenol B and the like.

Diols are used as one or a mixture of two or more. Of these, an alkylene glycol having 2 to 12 carbon atoms is preferable because it has excellent compatibility with a norbornene-based resin.

In the formula, A is selected from at least one selected from the group consisting of an alkylene dicarboxylic acid having 4 to 12 carbon atoms, a cycloalkylene dicarboxylic acid having 6 to 12 carbon atoms, and an allylene dicarboxylic acid having 8 to 16 carbon atoms. Represents the group to be derived.

Examples of alkylenedicarboxylic acids having 4 to 12 carbon atoms include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecandicarboxylic acid and the like.

Examples of cycloalkylenedicarboxylic acids having 6 to 16 carbon atoms include 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,5-decahydronaphthalenedicarboxylic acid, Includes 1,4-decahydronaphthalenedicarboxylic acid and the like.

Examples of allylenedicarboxylic acids having 8 to 16 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid and the like.

The dicarboxylic acid is used as one or a mixture of two or more. The dicarboxylic acid is preferably a mixture of an alkylenedicarboxylic acid and an allylene carboxylic acid. The content ratio of the alkylenedicarboxylic acid to the allylenedicarboxylic acid is preferably alkylenedicarboxylic acid: allylenedicarboxylic acid = 40: 60 to 99: 1, and more preferably 50:50 to 90:10.

In the formula, n represents an integer greater than or equal to 0.

The number average molecular weight of the polyester plasticizer is preferably in the range of 300 to 30,000, more preferably 300 to 700, and more preferably 300 to 600. When the number average molecular weight is above a certain level, bleed-out is likely to be suppressed. When the number average molecular weight is below a certain level, the compatibility with the norbornene-based resin is not easily impaired and the haze increase is easily suppressed.

The number average molecular weight of the polyester plasticizer can be measured by gel permeation chromatography. Specifically, using a gel permeation chromatography (GPC) measuring device (“HLC-8330” manufactured by Tosoh Corporation), the number average molecular weight (Mn) of the ester compound in terms of standard polystyrene under the following measurement conditions. Can be measured.

(Measurement condition)
Columns: "TSK gel SuperHZM-M" x 2 and "TSK gel SuperHZ-2000" x 2 Guard columns: "TSK SuperH-H"
Developing solvent: tetrahydrofuran Flow velocity: 0.35 mL / min The number average molecular weight of the polyester plasticizer can be adjusted by the reaction time of condensation or polycondensation.

The acid value of the polyester plasticizer is preferably 0.5 mgKOH / g or less, more preferably 0.3 mgKOH / g or less. The hydroxy group value of the polyester plasticizer is preferably 25 mgKOH / g or less, more preferably 15 mgKOH / g or less.

The polyester-based plasticizer is synthesized by a conventional method of esterification reaction of dicarboxylic acid, diol, and monocarboxylic acid for end sealing, or thermal melt condensation method by transesterification reaction, or dicarboxylic acid and monocarboxylic acid for end sealing. It can be carried out by any method of intercondensation of acid chloride and diol. The charging ratio of diol to dicarboxylic acid is adjusted so that the molecular end is diol.

The amount of the polyester plasticizer having the structure represented by the general formula (2) added to the norbornene resin is preferably in the range of 1 to 10% by mass. More preferably, it is in the range of 3 to 7% by mass. When the addition amount is 1% by mass or more, the effect of increasing the hardness of the polymer layer is recognized, and when it is 10% by mass or less, it is preferable from the viewpoint of enhancing dimensional stability and haze stability in a high temperature environment.

[5] Other Additives The polymer layer according to the present invention can contain various additives. Among them, the following ultraviolet absorbers, antioxidants, impact reinforcing agents and the like can be appropriately used.

(UV absorber)
The ultraviolet absorber applicable to the present invention is not particularly limited, and for example, an oxybenzophenone compound, a benzotriazole compound, a salicylate ester compound, a benzophenone compound, a cyanoacrylate compound, a triazine compound, a nickel complex salt compound, etc. Examples include inorganic powder.

Examples of the ultraviolet absorber applicable to the present invention include 5-chloro-2- (3,5-di-sec-butyl-2-hydroxylphenyl) -2H-benzotriazole and (2-2H-benzotriazole-). 2-yl) -6- (straight chain and side chain dodecyl) -4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone, etc., as well as chinubin 109, chinubin 171 and There are chinubins such as chinubin 234, chinubin 326, chinubin 327, chinubin 328, and chinubin 928, all of which are commercially available products manufactured by BASF Japan and can be preferably used.

The amount of the ultraviolet absorber used is not uniform depending on the type of the ultraviolet absorber, the conditions of use, etc., but is preferably 0.5 to 10% by mass, more preferably 0.6 to 4% by mass, based on the polymer layer. ..

(Antioxidant)
An antioxidant can be applied to the polymer layer according to the present invention.

In the present invention, commonly known antioxidants can be used. In particular, lactone-based, sulfur-based, phenol-based, double-bonded, hindered amine-based, and phosphorus-based compounds can be preferably used.

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

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

The phenolic compound preferably has a structure of 2,6-dialkylphenol, and is, for example, commercially available from "Irganox 1076", "Irganox 1010", and ADEKA Corporation, which are commercially available from BASF Japan Ltd. "ADEKA STAB AO-50" and the like can be mentioned.

The double bond compounds are commercially available from Sumitomo Chemical Co., Ltd. under the trade names of "Sumilizer GM" and "Sumilizer GS".

Examples of the hindered amine compound include "Tinuvin 144" and "Tinuvin 770" commercially available from BASF Japan Ltd. and "ADK STAB LA-52" commercially available from ADEKA Corporation.

Examples of the phosphorus-based compound include "Sumilizer GP" commercially available from Sumitomo Chemical Co., Ltd., "ADK STAB PEP-24G" commercially available from ADEKA Corporation, "ADK STAB PEP-36" and "ADK STAB 3010". , "Irgafos P-EPQ" commercially available from BASF Japan Ltd., and "GSY-P101" commercially available from Sakai Chemical Industry Co., Ltd.

(Impact reinforcement)
The polymer layer according to the present invention may contain at least one of core-shell type acrylic fine particles, a styrene-conjugated diene compound or a butyl acrylate compound as an impact reinforcing material in order to enhance 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 described in Japanese Patent Application Laid-Open No. 2009-84574, and internationally It is preferable to contain a core-shell type acrylic fine particle described in Publication No. 2009/0479224, and an impact reinforcing material such as a styrene-butadiene-based elastic organic fine particle described in JP2013-83907. ..

For example, the core-shell type acrylic fine particles are methyl methacrylate 80-98.
The innermost hard layer obtained by polymerizing a mixture of 9% by mass, 1 to 20% by mass of alkyl acrylate and 0.01 to 0.3% by mass of a polyfunctional graft agent, and 75 to 98.5% by mass of alkyl acrylate. A soft layer obtained by polymerizing a mixture of 0.01 to 5% by mass of a polyfunctional cross-linking agent and 0.5 to 5% by mass of a polyfunctional grafting agent, and 80 to 99% by mass of methyl methacrylate and 1 to 20% of alkyl acrylate. It has an outermost hard layer obtained by polymerizing a mass% mixture.

The styrene-conjugated diene compound is preferably a styrene-butadiene copolymer. The copolymer may be a rubber-like elastic body or elastic organic fine particles, and specifically, the elastic organic fine particles are preferably core-shell type particles.

The flexible polymer contains structural units derived from conjugated diene monomers and, optionally, structural units derived from other monomers. Examples of conjugated diene monomers include 1,3-butadiene (hereinafter, also referred to simply as "butadiene"), isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-Chloro-1,3-butadiene, milsen and the like are included, and butadiene and isoprene are preferable. Examples of other monomers include styrene components such as styrene and α-methylstyrene. The content ratio 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 a copolymer of acrylonitrile and styrene, a polymer containing a methacrylic acid ester such as methyl methacrylate as a main component, and the like.

Commercially available products include, for example, Metabrene C-140A, C-215A (above, manufactured by Mitsubishi Rayon Co., Ltd.), Toughpren 126, Asaflex 800, Asaflex 825 (above, manufactured by Asahi Kasei Chemicals Co., Ltd.), TR2000, TR2250. (The above is manufactured by JSR Corporation) and the like.

Examples of other rubber-like elastic bodies include acrylic acid ester-based rubber-like polymers, and rubber-like polymers containing an acrylic acid ester-based polymer containing butyl acrylate as a main component are preferable.

[6] Optical Properties of Polymer Layer The polymer layer according to the present invention has a retardation value Ro defined by the following formula (i) in the range of 0 to 10 nm, and the litter defined by the following formula (ii). The definition value Rt is in the range of -20 to 20 nm.

Equation (i)
Ro = (n _{x −} n _y ) × d
Equation (ii)
Rt = {(n _x + n _y ) /2- _nz } × d
In the above formulas (i) and (ii), Ro is the in-plane retardation value of the polymer layer, Rt is the retardation value in the thickness direction of the polymer layer, and n _x is the in-plane slow axis direction of the polymer layer. The refractive index of, _ny is the refractive index in the in-plane phase-advancing axis direction of the polymer layer, and _nz is the refractive index in the thickness direction of the polymer layer (refractive index is 23 ° C., under an environment of 55% RH, at a wavelength of 590 nm). Measurement), d represents the thickness (nm) of the polymer layer.

The retardation value is obtained by peeling the polymer layer from the support in the polarizing plate protective film of the present invention, and measuring the retardation value as the polymer layer by the following method and apparatus.

The retardation value Ro in the in-plane direction and the retardation value Rt in the thickness direction are set in an environment of 23 ° C. and 55% RH using an automatic birefringence meter Axoscan (Axo Scan Mueller Matrix Polarimeter: manufactured by Axometrics). Below, a three-dimensional refractive index measurement is performed at a wavelength of 590 nm, and it can be calculated from the obtained refractive indexes n _x , _ny , and n _z .

The retardation value Ro defined by the formula (i) defined above is in the range of 0 to 10 nm, and the retardation value Rt represented by the formula (ii) is in the range of -20 to 20 nm. It means that the polymer layer has a retardation value Ro (nm) in the direction and a retardation value Rt (nm) in the thickness direction of the film of almost zero.

An IPS-type liquid crystal display device obtained when the polymer layer side is bonded to an IPS-type liquid crystal cell by setting the in-plane retardation value Ro and the retardation value Rt in the thickness direction to almost zero. It is possible to effectively prevent light leakage when displaying black in. Further, since the thickness of the polymer layer is thin, it is possible to further reduce the thickness and weight of the polarizing plate and the liquid crystal display device.

The retardation value can be adjusted by adjusting the type of norbornene-based resin, the type and amount of polyester-based plasticizer, the mass of residual solvent, in particular, the use of aromatic organic solvent, coating conditions, and drying conditions.

[7] Support The support may be transparent or opaque and is not particularly limited, but a transparent resin film is preferable from the viewpoint of easily detecting coating failure or scratches. The term "transparent" as used in the present invention means that the total light transmittance is 60% or more, more preferably 70% or more, and particularly preferably 80% or more. The total light transmittance (%) is determined by, for example, a spectrophotometer (U-3300 manufactured by Hitachi High-Technologies Co., Ltd.), JIS K 7361-1: 1997 (a method for testing the total light transmittance of a plastic-transparent material). ) Is used to measure the total light transmittance (%) in the light wavelength range of 400 to 700 nm, and the value is averaged.

The material of the film used as the support is not particularly limited, and for example, a cellulose ester film, a polyester film, a polycarbonate film, a polyarylate film, a polysulfone (including polyether sulfone) film, and a polyethylene film. , Polypropylene film and other polyolefin films, cellophane, polyvinylidene chloride film, polyvinyl alcohol film, ethylene vinyl alcohol film, syndiotactic polystyrene film, norbornene resin film, polymethylpentene film, polyether ketone film, polyether ketone Examples thereof include imide film, polyamide film, fluororesin film, nylon film, polymethylmethacrylate film, acrylic film and the like. Among them, for the purpose of inspecting the optical characteristics in the manufacturing process, the support is preferably made of a transparent material, and it is also preferable that the support is inexpensive. Therefore, a polycarbonate film, a polyester film, or the like is preferable, and the support is made flat. A polyester film is preferably used because of its excellent properties.

The thickness of the support according to the present invention is preferably 10 to 100 μm, more preferably 15 to 50 μm. When the support is 10 μm or more, it is less likely to wrinkle when wound, and when it is 100 μm or less, the winding size of the polarizing plate protective film roll can be reduced and the weight can be reduced, so that it can be stored or stored. In terms of transportation, handling is unlikely to be hindered.

Further, the support may be a non-stretched film or a stretched film. When a stretched film is used, the stretching may be uniaxial stretching or biaxial stretching. The uniaxial stretching is preferably vertical uniaxial stretching utilizing the difference in rotation between two or more rolls, or tenter stretching in which both ends of the film are gripped and stretched in the width direction. Further, the film may be stretched in the vertical and horizontal directions.

[8] Method of Applying Polymer Layer The polymer layer containing the norbornene-based resin can be formed by coating the composition containing the norbornene-based resin on the support, and further heating and drying the coated layer.

The composition containing the norbornene-based resin can be applied by a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, a gravure coating method, a die coating method, or the like.

Of these, the microgravure coating method, the wire bar coating method, and the die coating method (see US Pat. No. 2,681294 and JP-A-2006-122889) are more preferable for forming the polymer layer containing the norbornene-based resin, and the die coating method is particularly preferable. The method is particularly preferred.

By forming a polymer layer containing a norbornene-based resin by using a coating method, it is possible to form a thin film that cannot be achieved by a method of forming a film by using a solution casting method or a melt casting method.

<Applying process>
FIG. 2 shows a diagram showing an example of a coating process that can be used in the present invention.

The support 12 (temporary support, etc.) sent out from the delivery machine 11 or the previous step is subjected to the coating step in the coating device 10. The coating device 10 is provided with a coating liquid supply unit (hereinafter, referred to as a coating head) 14 for applying the coating liquid sent from the coating liquid tank by a pump or the like to the support 12, and facing the coating head 14. , It is composed of a cylindrical backup roller 15 that supports the support 12 at the time of coating on the outer peripheral surface. The coating head 14 is arranged so as to face the support 12 in which the tip of the coating head travels continuously and in a non-contact state. The distance between the coating head 14 and the support 12 is adjustable. The coating head 14 is pumped from the coating liquid tank, and the coating amount for obtaining the required coating layer thickness can be controlled by adjusting the coating liquid delivery amount of the pump. Although not shown, it is preferable to use a metering pump as the pump because the supply flow rate of the coating liquid is stabilized. As the metering pump, various pumps such as a gear pump and a roller pump are used.

The coating step is preferably carried out in an environment of good dust-freeness and optimum temperature and humidity. It is preferable that the drying step after coating is also carried out in an environment of good dust-freeness and optimum temperature and humidity. The coating step and the like are preferably performed in a clean room, and in particular, the coating device 10 is preferably installed in an environment with a high degree of cleanliness. For this purpose, a form in which a downflow clean room or a clean bench is used together can be adopted.

After the coating step, it is preferably subjected to a drying step of drying the coating layer. As the drying device 16 used in the drying step, a general drying device can be used without limitation. For example, a convection drying method using hot air, a radiant drying method using radiant heat such as infrared rays, or the like can be used. When hot air is used, the temperature and speed of the hot air are adjusted to control the drying of the coating film. Further, as a method of applying hot air, a slit nozzle (a nozzle having a slit-shaped opening shape in the width direction of the strip-shaped support) or a punching nozzle (a porous flat plate nozzle) can be used.

In the method of the present invention, an organic solvent is preferably used as the solvent used for preparing the coating liquid when the polymer layer containing the norbornene-based resin is formed by coating. Examples of organic solvents include amides (eg, N, N-dimethylformamide), sulfoxides (eg, dimethyl sulfoxide), heterocyclic compounds (eg, pyridine), hydrocarbons (eg, benzene, hexane, toluene), alkyl halides. (Eg, chloroform, dichloromethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane), alkyl alcohols. (Example, methanol, ethanol, propanol). Further, two or more kinds of solvents may be mixed and used. Among the above, hydrocarbons, alkyl halides, esters, ketones and mixed solvents thereof are preferable. Above all, it is preferable to use an aromatic organic solvent because it has an effect of reducing the retardation value of the polymer layer.

Since the inclusion of the residual solvent in the polymer layer according to the present invention has the effect of facilitating the polar groups of the norbornene-based resin toward the surface side and improving the adhesion to the support, the residual solvent mass of the polymer layer Must be in the range of 500 to 10000 ppm.

In particular, the aromatic solvent is preferably contained in the range of 50 to 1000 ppm because it has the effect of reducing the retardation value.

Further, from the viewpoint of improving coatability, the alkyl halide-based solvent should be contained in the range of 300 to 5000 ppm, or the non-aromatic solvent (excluding the halide-based solvent) should be contained in the range of 300 to 6000 ppm. Is preferable.

[Method for quantifying solvent content]
The residual solvent content in the polymer layer can be quantified by headspace gas chromatography.

Quantification of residual solvent can be performed by headspace gas chromatography. That is, the measurement sample (the polymer layer) is sealed in a container, heated at the following temperature setting, for example, and the gas in the container is promptly injected into a gas chromatograph with the container filled with volatile components, and mass spectrometry is performed. The volatile components were quantified while identifying the compounds. The quantification of volatile components was performed by preparing a calibration curve in advance using a sample having a known concentration and collating the peak area of the volatile components obtained by the measurement with the calibration curve (the unit of residual solvent mass is Expressed as "ppm").
<Measurement conditions>
Headspace device: 7649 Headspace Sampler (manufactured by Agilent Technologies)
Temperature conditions: Transfer line 200 ° C, loop temperature 200 ° C
Sample volume: 0.8 g / 20 mL vial GC: 5890 (manufactured by Agilent Technologies)
MS: 5971 (manufactured by Agilent Technologies)
Column: DB-624 (30 m x inner diameter 0.25 mm)
Oven temperature: Initial temperature 40 ° C (holding time 3 minutes), heating rate 10 ° C / min, reaching temperature 200 ° C (holding time 5 minutes)
Measurement mode: SIM (select ion monitor) mode [9] Polarizing plate In the method for producing a polarizing plate to which the polarizing plate protective film of the present invention is applied, the polymer layer is peeled off from the support to form a film containing a polarizer. It may be laminated, or the polymer layer may be laminated on a film containing a polarizer, and then the support may be peeled off.

When laminating after peeling off the support, the polymer layer may be on the film side surface containing the polarizer, or the surface of the layer other than the polymer layer may be on the film side surface containing the polarizer. Good.

When the support is peeled off after laminating, the support is laminated so that the surface on the polymer-containing layer side of the support becomes the surface on the film side containing the polarizer. Lamination may be performed via an adhesive layer. The adhesive layer may be an adhesive or a layer containing an adhesive. That is, the polymer layer and the film containing the polarizer may be adhered or adhered with an adhesive or an adhesive. The adhesive is not particularly limited, but is a curable adhesive of an epoxy compound that does not contain an aromatic ring in the molecule as shown in JP-A-2004-245925, 360 to JP-A-2008-174667. An active energy ray-curable adhesive containing a photopolymerization initiator having a molar absorption coefficient of 400 or more at a wavelength of 450 nm and an ultraviolet curable compound as essential components, a (meth) acrylic compound described in JP-A-2008-174667. (A) A (meth) acrylic compound having two or more (meth) acryloyl groups in the molecule and (b) having a hydroxy group in the molecule and having a polymerizable double bond in 100 parts by mass of the total amount of Examples thereof include an active energy ray-curable adhesive containing one (meth) acrylic compound and (c) phenolethylene oxide-modified acrylate or nonylphenolethylene oxide-modified acrylate.

Polarizers include iodine-based polarizers, dye-based polarizers using dichroic dyes, and polyene-based polarizers. Iodine-based polarizers and dye-based polarizers are generally produced by using a polyvinyl alcohol-based film. Any polarizer may be used in the present invention. For example, the polarizer is preferably composed of polyvinyl alcohol (PVA) and a dichroic molecule. For a polarizer composed of polyvinyl alcohol (PVA) and a dichroic molecule, for example, the description in JP-A-2009-237376 can be referred to. The film thickness of the polarizer may be 50 μm or less, preferably 30 μm or less, more preferably 20 μm or less, and particularly preferably 10 μm or less.

The polymer layer according to the present invention may be bonded to the other surface of the polarizer, but another polarizing plate protective film may also be bonded. For example, as a conventional polarizing plate protective film, commercially available cellulose ester films (for example, Konica Minolta Tack KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC4FR, KC4KR, KC4DR, KC4SR, KC8UY, KC6UY, KC6UK, KC6UK KC8UE, KC8UY-HA, KC8UX-RHA, KC8UXW-RHA-C, KC8UXW-RHA-NC, KC4UXW-RHA-NC, and above, manufactured by Konica Minolta Co., Ltd. are preferably used.

[10] Liquid crystal display device By using the polarizing plate to which the polarizing plate protective film of the present invention is attached for the liquid crystal display device, various liquid crystal display devices having excellent visibility can be produced.

The above-mentioned polarizing plate can be used for liquid crystal display devices of various drive methods such as STN, TN, OCB, HAN, VA (MVA, PVA), IPS, OCB and the like. Preferably, it is an IPS type liquid crystal display device that requires a thin-film polarizing plate.

Normally, two polarizing plates, a polarizing plate on the viewing side and a polarizing plate on the backlight side, are used in the liquid crystal display device, but it is preferable to use the polymer layer side of the polarizing plate on the liquid crystal cell side, and both polarizations are used. It is also preferable to use it as a plate, and it is also preferable to use it as a polarizing plate on one side.

The orientation of the polarizing plate in the IPS type liquid crystal display device can be determined by referring to Japanese Patent Application Laid-Open No. 2005-234431.

The liquid crystal cell used in the present invention is a glass substrate including a liquid crystal layer and a pair of substrates sandwiching the liquid crystal layer, and the thickness of the pair of substrates is in the range of 0.3 to 0.7 mm. , Preferable from the viewpoint of thinning and weight reduction of the liquid crystal display device.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the examples, the indication of "parts" or "%" is used, but unless otherwise specified, it indicates "parts by mass" or "% by mass".

First, the following materials were prepared as the materials used in the examples.

<Norbornene resin>
As a norbornene-based resin having a norbornane skeleton represented by the general formula (1), the following a to d were prepared as the types of R of −COOR (weight average molecular weight Mw = 140000 in each case).

a: R = -CH ₃ , b: R = -C ₂ H ₅ , c: R = -C ₃ H ₇ (n or iso), d: R = -C ₄ H ₉
<Silicone additive>
(Silicone manufactured by Kyoeisha Chemical Co., Ltd.)
GL-01: Acrylic modified silicone (manufactured by Kyoeisha Chemical Co., Ltd.), weight average molecular weight Mw = 5200
GL-03: Acrylic modified silicone (manufactured by Kyoeisha Chemical Co., Ltd.), weight average molecular weight Mw = 4100
GL-04R: Acrylic modified silicone (manufactured by Kyoeisha Chemical Co., Ltd.), weight average molecular weight Mw = 4700
(Silicone manufactured by Nissin Chemical Industry Co., Ltd.)
Silface SAG005: Polyether-modified silicone (manufactured by Nisshin Kagaku Kogyo Co., Ltd., Silface SAG005), weight average molecular weight Mw = 2800
Silface SAG008: Polyether-modified silicone (manufactured by Nissin Chemical Co., Ltd., Silface SAG008), weight average molecular weight Mw = 7900
<Support>
Polyethylene terephthalate film Lumirror (registered trademark) (U403) manufactured by Toray Industries, Inc., film thickness 50 μm
KC4UY (TAC film) manufactured by Konica Minolta Co., Ltd., film thickness 40 μm
<Mat agent>
The following silica particles manufactured by Nippon Aerosil Co., Ltd. were prepared.

(Product name) (Surface modifier) (Degree of hydrophobization by MW method)
R972: Dimethylsilane: Methanol 42% by volume
R812: Trimethylsilane: Methanol 48% by volume
R805: Octylsilane: Methanol 50% by volume
R816: Hexadecylsilane: 54% by volume of methanol
NKC130: Didimethylsiloxane: Methanol 67% by volume
R711: Methacryloxysilane: Methanol 55% by volume
RY300: Didimethylsiloxane: Methanol 69% by volume
R104: Dimethylsiloxane cyclic body: 60% by volume of methanol
RA200H: Aminosilane: Methanol 51% by volume
200V: No surface modifier added: Methanol 15% by volume
<Methanol wettability (MW) method>
In a mixed solution of methanol and pure water, the same amount (same volume) of silica particles is added to each solution while changing the mixing ratio of methanol to pure water, and the mixture is stirred and mixed, and each of the mixed solutions is centrifuged. The volume of the sediment of the silica particles is determined by separating them, and the mixture ratio of methanol in the solution in which the volume of the sediment of the silica particles in the solution is 50%.

It can be said that the higher the mixing ratio of methanol, the higher the degree of hydrophobicity of the silica particles.

<Polyester plasticizer>
Polyester plasticizers A and B having the following structures were prepared.

[Example 1]
<Preparation of polarizing plate protective film 101>
<Formation of norbornene-based resin-containing polymer layer>
As a support, a coating liquid for forming a norbornene-based resin-containing polymer layer having the following composition was applied on a polyethylene terephthalate film Lumirror (registered trademark) (U403 / film thickness 50 μm) manufactured by Toray Industries, Inc. using the coating apparatus shown in FIG. 70 mL / m ² was continuously applied. The transport speed of the support was 30 m / min, and the polymer layer was dried with warm air at 80 ° C. for 60 seconds, and the film thickness of the polymer layer after drying was 0.5 μm. The film was applied with a width of 1.6 m and a length of 5000 m, heat-treated at 130 ° C. for 60 seconds in order to dry and reduce the retardation value Rt, and then wound around a roll to prepare a polarizing plate protective film 101. ..

(Composition of coating liquid for forming a polymer layer containing norbornene resin)
Norbornen-based resin a 100 parts by mass Silicone additive GL-03 1.0 part by mass Dichloromethane 330 parts by mass Ethanol 20 parts by mass or more is put into a closed container, heated and completely dissolved while stirring, Azumi Filter Paper Co., Ltd. ) Azumi filter paper No. 24 was used for filtration to prepare a coating solution.

<Preparation of polarizing plate protective films 102 to 123 and 125 to 129>
In the production of the polarizing plate protective film 101, the type of norbornene-based resin used for the polymer layer, the drying conditions of the polymer layer (control of the residual solvent mass), the film thickness after drying, the presence or absence of a support, the type of silicone-based additive, and Polarizing plate protective films 102 to 123 and 125 to 129 were prepared in the same manner except that the amounts were changed as shown in Table 1.

The polarizing plate protective films 108 to 115 were coated with a polymer layer, dried, and then stretched together with the support in the longitudinal direction or the width direction using a tenter stretching device, and controlled so as to have the retardation values shown in Table 1. ..

<Preparation of polarizing plate protective film 124>
<Formation of norbornene-based resin-containing polymer layer by melt casting>
[Resin composition]
Norbornene resin a 100 parts by mass Silicone additive GL-03 1.0 part by mass The obtained resin composition was melt-kneaded at 230 ° C. with a twin-screw extruder and extruded into a strand shape. The resin composition extruded into a strand shape was cooled with water and then cut to obtain pellets.

Dehumidified air having a temperature of 70 ° C. was circulated through the obtained pellets for 5 hours or more to dry them, and then the pellets were put into a uniaxial extruder while maintaining the temperature of 100 ° C. The water content of the pellets charged into the uniaxial extruder was 120 ppm.

The obtained pellets were melt-kneaded at 230 ° C. with a uniaxial extruder and then extruded from a T-die onto a support to bring the polymer layer into a dry film thickness of 5 μm. A polarizing plate protective film 124 was prepared by winding it around a roll body having a width of 1.6 m and a length of 5000 m.

≪Evaluation≫
(1) Measurement of retardation value of polymer layer The polymer layer of the polarizing plate protective film was peeled off from the support, and the retardation values Ro and Rt were measured by the following methods.

Equation (i)
Ro = (n _{x −} n _y ) × d
Equation (ii)
Rt = {(n _x + n _y ) /2- _nz } × d
In the above formulas (i) and (ii), Ro is the in-plane retardation value of the polymer layer, Rt is the retardation value in the thickness direction of the polymer layer, and n _x is the in-plane slow axis direction of the polymer layer. The refractive index of, _ny is the refractive index in the in-plane phase-advancing axis direction of the polymer layer, and _nz is the refractive index in the thickness direction of the polymer layer (refractive index is 23 ° C., under an environment of 55% RH, at a wavelength of 590 nm). Measurement), d represents the thickness (nm) of the polymer layer.

The retardation value Ro in the in-plane direction and the retardation value Rt in the thickness direction are set in an environment of 23 ° C. and 55% RH using an automatic birefringence meter Axoscan (Axo Scan Mueller Matrix Polarimeter: manufactured by Axometrics). Below, a three-dimensional refractive index measurement was performed at a wavelength of 590 nm, and it was calculated from the obtained refractive indexes n _x , n _y , and n _z .

(2) Residual solvent mass The polymer layer of the polarizing plate protective film was peeled off from the support, and the residual solvent mass of the polymer layer was quantified by the following method.

[Method for quantifying residual solvent]
The solvent content in the polymer layer was quantified by headspace gas chromatography under the following equipment and conditions.

The measurement sample (the above polymer layer) is sealed in a container, heated in the following temperature range, and the gas in the container is promptly injected into a gas chromatograph with the container filled with volatile components, and mass spectrometry is performed to perform mass spectrometry. The volatile components were quantified while identifying the above. The quantification of volatile components was performed by preparing a calibration curve in advance using a sample having a known concentration and collating the peak area of the volatile components obtained by the measurement with the calibration curve (the unit of residual solvent mass is Expressed as "ppm").

<Measurement conditions>
Headspace device: 7649 Headspace Sampler (manufactured by Agilent Technologies)
Temperature conditions: Transfer line 200 ° C, loop temperature 200 ° C
Sample volume: 0.8 g / 20 mL vial GC: 5890 (manufactured by Agilent Technologies)
MS: 5971 (manufactured by Agilent Technologies)
Column: DB-624 (30 m x inner diameter 0.25 mm)
Oven temperature: Initial temperature 40 ° C (holding time 3 minutes), heating rate 10 ° C / min, reaching temperature 200 ° C (holding time 5 minutes)
Measurement mode: SIM (select ion monitor) mode (3) Scratch resistance evaluation The wound polarizing plate protective film was unwound, and the presence or absence of scratches (scratch resistance) was visually evaluated by the following method.

Irradiate light from the polymer layer side of the polarizing plate protective film using a sodium lamp (KNL-35D, manufactured by Lytest Co., Ltd.) and a commercially available three-wavelength fluorescent lamp to prevent unevenness and scratches on the surface of the polymer layer in a dark room. Evaluated. The evaluated site is the inner surface excluding the end 5 cm.

◎: No scratches ○: Slight scratches but no practical problem △: Slight scratches and practical problems ×: Scratches are apparent and practical problems ( 4) Evaluation of winding shape The winding shape of the rolled body was visually evaluated according to the following criteria.

◎: No winding wrinkles or winding deformation ○: There are slight winding wrinkles and winding deformation, but there is no practical problem △: There are some winding wrinkles and winding deformation, and there is a practical problem ×: Winding wrinkles and winding deformation Obviously, there is a problem in practical use. As described above, Table 1 shows the composition and evaluation results of the polarizing plate protective film.

From Table 1, the polarizing plate protective films 102 to 105, 107, 108, 111 to 114, 118 to 123, and 126 to 128 of the present invention are thin films having low retardation values and excellent scratch resistance and winding shape. It can be seen that the polarizing plate protective film has a norbornene-based resin-containing polymer layer.

The polarizing plate protective film 106, which is a comparative example, was insufficient for thinning the polarizing plate.

Since the retardation values of the polarizing plate protective films 109, 110 and 115 as comparative examples were outside the range of the present invention, when a polarizing plate was produced as the polarizing plate protective film and then attached to the IPS type liquid crystal display device, the field of view The angular characteristics were inferior.

In the polarizing plate protective film 124, which is a comparative example, when a polymer layer was formed by melt casting, a uniform thin film could not be formed.

Since the polarizing plate protective film 125, which is a comparative example, has a large residual solvent mass, the rigidity of the polymer layer is lowered and the scratch resistance is inferior.

In the polarizing plate protective film 129, which is a comparative example, the strength of the polymer layer was lowered due to the long side chain of the norbornene-based resin, and the scratch resistance was inferior.

[Example 2]
<Preparation of polarizing plate protective film 201>.
In the production of the polarizing plate protective film 103, the polarizing plate protective film 201 was produced in the same manner except that the following silica particles were added to the coating liquid for forming the polymer layer.

(Preparation of fine particle dispersion)
Silica particles (Aerosil R812 manufactured by Nippon Aerosil Co., Ltd.) 11% by mass
Dichloromethane 89% by mass
The above was stirred and mixed with a dissolver for 50 minutes, and then dispersed using a menton-gorin disperser to prepare a fine particle dispersion.
(Preparation of fine particle additive solution 1)
Dichloromethane was placed in a dissolution tank, and the fine particle dispersion prepared above was slowly added to 50% by mass while stirring the dichloromethane sufficiently. Further, the particles were dispersed by an attritor so that the particle size of the secondary particles became a predetermined size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution 1.

(Composition of coating liquid for forming a polymer layer containing norbornene resin)
Norbornen resin a 100 parts by mass Silicone additive GL-03 1.0 part by mass Fine particle addition liquid Add an amount of 0.10% by mass in the film dichloromethane 330 parts by mass Ethanol 20 parts by mass or more is put into a closed container. Azumi Filter Paper No. 1 manufactured by Azumi Filter Paper Co., Ltd. was completely dissolved while heating and stirring. 24 was used for filtration to prepare a coating solution.

<Preparation of polarizing plate protective films 202 to 214>
In the production of the polarizing plate protective film 201, the polarization was carried out in the same manner except that the amount of silica particles R812 added and the types of silica particles (R972, R805, R816, NKC130, R711, RY300, R104, RA200H, 200V) were changed. Plate protective films 202 to 214 were produced.

Using the produced polarizing plate protective films 201 to 214, the retardation value of the polymer layer was measured, the scratch resistance was evaluated, and the winding shape was evaluated in the same manner as in Example 1. The results are shown in Table 2.

By adding the matting agent, the slipperiness was improved, and the result was that the winding shape was excellent. Further, the polarizing plate protective film using silica particles having a degree of hydrophobicity of 45% by volume or more in the hydrophobicity test by the MW method is likely to have a large amount of matting agent oriented on the surface of the polymer layer, and thus has scratch resistance. Was also a good result.

However, the polarizing plate protective film 204 to which 0.70% by mass of the matting agent was added had a slightly high haze.

[Example 3]
<Preparation of polarizing plate protective film 301>.
In the production of the polarizing plate protective film 103, the polarizing plate protective film 301 was produced in the same manner except that polyester A was added to the coating liquid for forming the polymer layer.

(Composition of coating liquid for forming a polymer layer containing norbornene resin)
Norbornen resin a 100 parts by mass Silicone additive GL-03 1.0 part by mass Polyester A 1.0 part by mass dichloromethane 330 parts by mass Ethanol 20 parts by mass <Preparation of polarizing plate protective films 302 to 309>
In the preparation of the polarizing plate protective film 301, the polarizing plate protective films 302 to 309 were prepared in the same manner except that polyester A and polyester B were added to the coating liquid for forming the polymer layer in different amounts.

Using the produced polarizing plate protective films 301 to 309, the retardation value measurement of the polymer layer, the scratch resistance evaluation, the winding shape evaluation, and the following durable winding shape evaluation were performed in the same manner as in Example 1. The results are shown in Table 3.

(5) Evaluation of durable winding shape After storing the produced polarizing plate protective film roll body in an environmental test room at 60 ° C. and 80% RH for one month, the rolled body is visually evaluated according to the following criteria. did.

⊚: No winding deformation ○: There is slight winding deformation but no problem in practical use △: There is some winding deformation and there is a practical problem as it is ×: There is obvious winding deformation and there is a practical problem

From Table 3, it can be seen that by adding the polyester-based plasticizer, excellent effects are exhibited not only in the scratch resistance and the winding shape but also in the durable winding shape.

[Example 4]
<Preparation of polarizing plate protective films 401 to 403>.
In the production of the polarizing plate protective film 202, the amount of the matting agent added, the polyester-based plasticizing agent A added, and as a support, a polyethylene terephthalate film Lumirror (registered trademark) manufactured by Toray Co., Ltd. (U403 / 50 μm, abbreviated as PET), KC4UY manufactured by Konica Minolta Co., Ltd. (TAC film / 40 μm, abbreviated as TAC), polyethylene film R7832C manufactured by Toray Processing Film Co., Ltd., film thickness 50 μm, abbreviated as PE) and a polymer layer formed without a support. , Plate plate protective films 401 to 404 were prepared.

Using the produced polarizing plate protective films 401 to 404, the retardation value measurement of the polymer layer, the scratch resistance evaluation, the winding shape evaluation, and the following flatness evaluation were performed in the same manner as in Example 1. Table 4 shows the structure of the polarizing plate protective film and the evaluation results.

(6) Evaluation of flatness A sample is cut into 1 m squares, and light is irradiated from the polymer layer side of the polarizing plate protective film using a commercially available three-wavelength fluorescent lamp to obtain foreign matter, scratches, pressed marks, streaks, and streaks on the surface. The degree of distortion of the reflected image of the fluorescent lamp reflected on the surface of the polymer layer due to unevenness was evaluated in a dark room.

⊚: No distortion of the reflected image of the fluorescent lamp and excellent flatness ○: Slight distortion of the reflected image of the fluorescent lamp is not a problem in practical use △: Distortion of the reflected image of the fluorescent lamp is generated Somewhat inferior in flatness ×: There is a clear distortion of the reflected image of the fluorescent lamp, and there is a practical problem in flatness.

From Table 4, it can be seen that the use of the polyester resin film as the support is excellent in scratch resistance, winding shape and flatness.

[Example 5]
<Preparation of polarizing plate protective film 501>
In the production of the polarizing plate protective film 103, the polarizing plate protective film 501 was produced in the same manner except that the solvent type in the coating liquid for forming the polymer layer was changed and no heat treatment was performed to reduce the retardation value Rt. ..

(Composition of coating liquid for forming a polymer layer containing norbornene resin)
Norbornene resin a 100 parts by mass Silicone additive GL-03 1.0 part by mass Dichloromethane 330 parts by mass <Preparation of polarizing plate protective film 502>
In the production of the polarizing plate protective film 501, the polarizing plate protective film 502 was produced in the same manner except that the solvent type in the coating liquid for forming the polymer layer was changed.

(Composition of coating liquid for forming a polymer layer containing norbornene resin)
Norbornene resin a 100 parts by mass Silicone additive GL-03 1.0 part by mass Toluene 50 parts by mass dichloromethane 280 parts by mass Using the prepared polarizing plate protective films 501 and 502, the litter of the polymer layer is the same as in Example 4. The foundation value was measured, the scratch resistance was evaluated, the winding shape was evaluated, and the flatness was evaluated. Table 5 shows the structure of the polarizing plate protective film and the evaluation results.

From Table 5, it can be seen that the retardation value is further reduced when the residual solvent of the polymer layer contains an aromatic solvent.

F Polarizing plate protective film 1 Support 2 Polymer layer 10 Coating device 11 Feeder 12 Support 13 Conveying roller 14 Coating head 15 Backup roller 16 Dryer

Claims (5)

A polarizing plate protective film obtained by winding a long film having a polymer layer containing a norbornene resin on a support as a roll.
The layer thickness of the polymer layer is in the range of 1 to 10 μm.
The norbornene-based resin is a norbornene-based resin having a norbornane skeleton represented by the following general formula (1).
The retardation value Ro defined by the following formula (i) of the polymer layer is in the range of 0 to 10 nm, and the retardation value Rt defined by the following formula (ii) is in the range of -20 to 20 nm. And
The polymer layer contains a silicone-based additive in the range of 0.01 to 5.0% by mass with respect to all the components excluding the solvent in the material constituting the polymer layer, and
A polarizing plate protective film, wherein the polymer layer contains a residual solvent containing an aromatic solvent, and the mass of the residual solvent is in the range of 500 to 10000 ppm.

[In the formula, R represents a linear or branched alkyl group having 1 to 3 carbon atoms. ]
Equation (i)
Ro = (n _{x −} n _y ) × d
Equation (ii)
Rt = {(n _x + n _y ) /2- _nz } × d
Wherein, Ro-plane direction of the retardation value of the polymer layer, Rt is the thickness direction of the retardation value of the polymer layer, n _x is a refractive index in a slow axis direction of the polymer layer, n _y is the polymer layer In-plane refractive index in the phase-advancing axis direction, _nz is the refractive index in the thickness direction of the polymer layer (refractive index is measured at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH), and d is the thickness of the polymer layer. Represents (nm). ] The polarizing plate protective film according to claim 1, wherein the polymer layer contains a matting agent within a range of 0.1 to 0.5% by mass of the total mass of the polymer layer. The polarizing plate protective film according to claim 2, wherein the matting agent is silica particles, and the mixing ratio of methanol is 45% by volume or more in the hydrophobicity test by the methanol wettability method. The polarizing plate protective film according to any one of claims 1 to 3, wherein the polymer layer further contains a polyester-based plasticizer. The polarizing plate protective film according to any one of claims 1 to 4 , wherein the support is a polyester resin film.

Images