TWI698477B - Thermoplastic resin film - Google Patents

Abstract

An object of the present invention is to provide a thermoplastic resin film, which is excellent in heat resistance, less likely to contract under a high temperature condition and less likely to rupture during stretching, as well as suitable for a polarizer protective film.

Solving means of the present invention is a thermoplastic resin film formed from a resin composition that comprises: a resin (A) which contains methacrylate monomer units and aromatic vinyl monomer units, and a resin (B) which contains methacrylate monomer units and doesn’t contain aromatic vinyl monomer units, wherein the resin A is a resin that the content of aromatic vinyl monomer units is 50 wt% or more relative to 100 wt% of total monomer units constituting the resin A; the resin B is a resin that the content of metharcylate monomer units is 50 wt% or more relative to 100 wt% of total monomer units constituting the resin B; and the ratio (W_b/W_a) of the weight of resin B (W_b) to the content of metharcylate monomer units of resin A (W_a) is larger than 1.

Description

Thermoplastic resin film

The present invention relates to a thermoplastic resin film, and also relates to a stretched film formed by stretching it and a polarizer protective film.

Liquid crystal display devices usually have a polarizing plate. As far as the polarizing plate is concerned, the following polarizing plate is usually used: at least one side of the polarizing plate made of polyvinyl alcohol resin with dichroic dye adsorption and alignment is arranged for protection It is made of polarizer protective film of polarizer.

Liquid crystal display devices, for example, are often used in high-temperature environments such as the interior of automobiles. Because the polarizer has the property of being easy to shrink in high-temperature environments, it is required to have excellent heat resistance and try to suppress polarized light. The film shrinks, and the polarizer protective film is not easy to shrink under high temperature environment.

Generally, as a polarizer protective film, a thermoplastic resin film can be used directly, or a stretched film obtained by stretching a thermoplastic resin film can be used. Patent Document 1 describes a stretched thermoplastic resin film composed of an acrylic copolymer having (meth)acrylic monomer units, vinyl aromatic monomer units, and lactone ring monomer units The stretched film is used as a polarizer protective film. The thermoplastic resin film described in Patent Document 1 may be easily broken due to stretching, and there is room for improvement in workability during stretching.

Prior art literature

Patent literature

[Patent Document 1] JP 2007-63541 A

In order to provide a thermoplastic resin film that is excellent in heat resistance, does not easily shrink in a high-temperature environment, and does not easily break due to stretching, the inventors have devoted themselves to research and completed the present invention.

The present invention includes the following.

[1] A thermoplastic resin film consisting of a resin composition containing resin (A) and resin (B), wherein the resin (A) contains methacrylate monomer units and aromatic vinyl monomers Units; The resin (B) contains methacrylate monomer units and does not contain aromatic vinyl monomer units; relative to 100% by weight of all monomer units constituting the resin (A), the resin (A) is aromatic A resin with a group vinyl monomer unit content ratio of 50% by weight or more, relative to 100% by weight of all monomer units constituting the resin (B), the resin (B) type methacrylate monomer unit content ratio is 50 For resins with a weight% or more, the ratio (W _B /W _A ) of the weight (W _B ) of the resin ( _B ) to the content (W _A ) of the methacrylate monomer unit in the resin ( _A ) is greater than 1.

[2] The thermoplastic resin film according to [1], wherein the resin composition system further contains rubber elastomer particles.

[3] The thermoplastic resin film according to [1] or [2], wherein the resin (A) further contains a cyclic acid anhydride monomer unit, and the melt mass flow rate of the resin composition is 1.2 g/10 min the above.

[4] A stretched film obtained by stretching the thermoplastic resin film described in any one of [1] to [3].

[5] A polarizer protective film composed of the thermoplastic resin film described in any one of [1] to [3] or the stretched film described in [4].

[6] A polarizing plate in which the polarizer protective film described in [5] is arranged on at least one surface of the polarizer.

According to the present invention, it is possible to provide a thermoplastic resin film that is excellent in heat resistance, does not easily shrink in a high-temperature environment, and is not easily broken due to stretching, and a stretched film formed by stretching the same. In addition, it is possible to provide a polarizer protective film composed of such a thermoplastic resin film or stretched film, and also to provide a polarizer in which the polarizer protective film is further arranged on one side of the polarizer.

1‧‧‧Extrusion machine

2‧‧‧Plastic mold

3‧‧‧Film-like molten resin

4‧‧‧Cooling device

5‧‧‧The first cooling roll

6‧‧‧Second cooling roll

7‧‧‧The third cooling roll

A‧‧‧Thermoplastic resin film

Figure 1 shows the thermoplastic resin thin film of an embodiment of the present invention A schematic explanatory diagram of the film manufacturing method.

(Form to implement the invention) [Resin composition]

The thermoplastic resin film of the present invention is composed of a resin composition containing resin (A) and resin (B), wherein the resin (A) contains methacrylate monomer units and aromatic Vinyl monomer unit; this resin (B) contains methacrylate monomer unit and does not contain aromatic vinyl monomer unit.

[Resin (A)]

The resin (A) constituting the resin composition is a resin containing methacrylate monomer units and aromatic vinyl monomer units.

The methacrylate monomer unit is a monomer unit introduced from a methacrylate monomer. Examples of methacrylate monomers include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, and isobutyl methacrylate. C1-C8 alkyl or cycloalkyl methacrylate monomers such as ester, tert-butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, etc. Two or more types of methacrylate monomers can also be used in combination. In particular, alkyl ester monomers having 1 to 7 carbon atoms of methacrylic acid are preferred, and in terms of heat resistance and transparency of the resin (A), methyl methacrylate is more preferred.

Relative to 100% by weight of all monomer units constituting the resin (A), the content ratio of the methacrylate monomer unit in the resin (A) is preferably from 5 to 40% by weight. For resin (A) In terms of transparency, 5 wt% to 35 wt% is more preferred, 10 wt% to 30 wt% is even more preferred, and 15 wt% to 25 wt% is particularly preferred.

(式中，R¹及R²係各自獨立地表示氫原子、鹵素原子、羥基、烷氧基、硝基或碳數1至12的烷基，n係表示1至3的整數)。 The aromatic vinyl monomer unit is a monomer unit introduced from an aromatic vinyl monomer. In this specification, the aromatic vinyl monosystem means a monomer having a structure in which an unsubstituted vinyl group or a substituted vinyl group is bonded to an aromatic ring. As a specific example of the aromatic vinyl monomer unit, a monomer unit represented by the following formula (1) can be given,

(In the formula, R ¹ and R ² each independently represent a hydrogen atom, a halogen atom, a hydroxyl group, an alkoxy group, a nitro group, or an alkyl group having 1 to 12 carbons, and n represents an integer of 1 to 3).

As the halogen atom in the formula (1), a fluorine atom, a chlorine atom, and a bromine atom can be mentioned. Examples of alkyl groups having 1 to 12 carbon atoms include straight-chain methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, 2-ethylhexyl, etc. The alkyl or branched chain is preferably an alkyl having 1 to 4 carbon atoms, and more preferably a methyl group.

R ¹ is preferably a hydrogen atom or a methyl group. R ² is preferably a hydrogen atom, and n is preferably 1. The R ¹ and R ² systems may be the same or different from each other.

Examples of aromatic vinyl monomers include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4-dimethylstyrene, 2,5- Dimethylstyrene, 2-methyl-4-chlorostyrene, 2,4,6-trimethylstyrene, α-methylstyrene, cis-β-methylstyrene, trans-β -Methylstyrene, 4-methyl-α-methylstyrene, 4-fluoro-α-methylstyrene, 4-chloro-α-methylstyrene, 4-bromo-α-methylstyrene , 4-tert-butylstyrene, 2-fluorostyrene, 3-fluorostyrene, 4-fluorostyrene, 2,4-difluorostyrene, 2-chlorostyrene, 3-chlorostyrene, 4 -Chlorostyrene, 2,4-dichlorostyrene, 2,6-dichlorostyrene, 2-bromostyrene, 3-bromostyrene, 4-bromostyrene, 2,4-dibromostyrene, α-bromostyrene, β-bromostyrene, 2-hydroxystyrene and 4-hydroxystyrene, etc., preferably styrene and α-methylstyrene. Two or more kinds of aromatic vinyl monomers can also be used in combination.

The content ratio of the aromatic vinyl monomer unit in the resin (A) is 50% by weight or more relative to 100% by weight of all monomer units constituting the resin (A). Since the thermoplastic resin film of the present invention contains such resin (A), it is an excellent thermoplastic resin film in terms of dimensional stability in a high-temperature environment. The content of the aromatic vinyl monomer unit in the resin (A) is 50% to 80% by weight in terms of the transparency, heat resistance and dimensional stability of the thermoplastic resin film of the present invention in a high temperature environment Preferably, it is more preferably 55% to 75% by weight, and even more preferably 60% to 70% by weight.

(式中，R³及R⁴係各自獨立地表示氫原子、鹵素原子、碳數1至12的烷基或苯基)。 A preferable resin (A) contains a cyclic acid anhydride monomer unit. The cyclic acid anhydride monomer unit is introduced from the cyclic acid anhydride monomer. As a specific example of the cyclic acid anhydride monomer unit, a cyclic acid anhydride monomer unit represented by the following formula (2) can be given,

(In the formula, R ³ and R ⁴ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbons, or a phenyl group).

As the halogen atom in the formula (2) and the alkyl group having 1 to 12 carbons, the same as the above in the formula (1) can be exemplified.

R ³ and R ⁴ are preferably hydrogen atoms. The R ³ and R ⁴ series may be the same or different from each other.

Examples of the cyclic acid anhydride monomer include maleic anhydride, citraconic anhydride, dimethyl maleic anhydride, dichloromaleic anhydride, bromomaleic anhydride, and dibromomaleic anhydride. Diacid anhydride, phenyl maleic anhydride and diphenyl maleic anhydride are preferably maleic anhydride. Two or more types of cyclic acid anhydride monomers can also be used in combination.

With respect to 100% by weight of all monomer units constituting the resin (A), the content ratio of the cyclic anhydride monomer unit in the resin (A) is preferably 5 weight in terms of the transparency and heat resistance of the resin (A) % To 30% by weight, more preferably 10% to 25% by weight, particularly preferably 10% to 20% by weight.

As long as the effect of the present invention is not impaired, the resin (A) may also contain monomer units other than the above-mentioned monomer units, that is, methacrylate monomer units, aromatic vinyl monomer units, and cyclic anhydride monomer units. . The monomer units other than the above monomer units are introduced from the following monomers The monomer unit only needs to be a monomer that can be copolymerized with at least one monomer among the monomers introduced into the above monomer unit, preferably a monomer unit introduced from the following monomers: can be combined with the introduction of the above three monomers All the monomers of the monomer unit are copolymerized. Relative to 100% by weight of all monomer units constituting the resin (A), the content of monomer units other than the above-mentioned monomer units is preferably 50% by weight or less, more preferably 30% by weight or less, and 10% by weight % Or less is better.

The weight average molecular weight of the resin (A) is preferably 90,000 to 300,000, preferably 100,000, in terms of film handling properties during the molding of the thermoplastic resin film of the present invention or the stretching of the thermoplastic resin film of the present invention. To 250,000, more preferably 110,000 to 200,000.

The resin (A) can be produced by polymerizing the respective monomers using well-known methods such as block polymerization, solution polymerization, emulsion polymerization, suspension polymerization, and casting polymerization. By changing the use of monomers The amount of each monomer unit in the resin (A) can be adjusted.

[Resin (B)]

The resin (B) constituting the resin composition is a resin containing methacrylate monomer units and not containing aromatic vinyl monomer units.

Examples of the methacrylate monomer to which the methacrylate monomer unit is introduced include the same as the aforementioned resin (A), and methyl methacrylate is preferred. It may contain two or more types of methacrylate monomer units.

The methacrylate monomer unit in the resin (A) and the methacrylate monomer unit in the resin (B) are preferably the same.

Relative to 100% by weight of all monomer units constituting resin (B), the content of methacrylate monomer units in resin (B) is 50% by weight or more, preferably 70% by weight or more, and 90% by weight The above is more preferable, and even more preferably 95% by weight.

Resin (B) is a resin that does not contain aromatic vinyl monomer units, that is, a resin with an aromatic vinyl monomer unit content of 0 (zero)% by weight, and may also contain monomer units other than methacrylate And other monomer units of aromatic vinyl monomer units. Examples of other monomers include methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, etc. Acrylic monomers; unsubstituted or substituted styrene monomers such as styrene, vinyl toluene, α-methylstyrene, chlorostyrene, and bromostyrene; unsaturated carboxylic acid monomers such as methacrylic acid and acrylic acid ; Unsaturated nitrile monomers such as acrylonitrile and methacrylonitrile; cyclic anhydride monomers such as maleic anhydride; phenyl maleimide, cyclohexyl maleimide, etc. The cyclic imine monomer is preferably an acrylate monomer.

In terms of film handling properties during the molding of the thermoplastic resin film of the present invention or the stretching of the thermoplastic resin film of the present invention, the weight average molecular weight of the resin (B) is preferably 90,000 to 300,000, and more preferably 100,000 to 250,000. Good, even more preferably from 110,000 to 200,000.

Resin (B) can be obtained by using well-known methods such as block polymerization, solution polymerization, emulsion polymerization, suspension polymerization, casting polymerization, etc. The method polymerizes methacrylate monomer and other monomers as necessary.

[The thermoplastic film of the present invention]

The thermoplastic resin film of the present invention is composed of a resin composition containing resin (A) and resin (B).

The thermoplastic resin film of the present invention has a ratio (W _B /W _A ) greater than the weight (W _B ) of the resin ( _B ) to the content (W _A ) of the methacrylate monomer unit in the resin (A) When constituted by the resin composition of 1, since W _B /W _{A is} greater than 1, it is less likely to be broken during stretching and becomes a thermoplastic resin film with good handleability. The ratio (W _B /W _A ) is more preferably 1.5 or more, usually 30 or less.

The content of resin (A) and resin (B) in the resin composition constituting the thermoplastic resin film of the present invention can be based on the content (W _A ) of the methacrylate monomer unit in the resin ( _A ) and The method to satisfy the above ratio (W _B /W _A ) is appropriately selected. For example, the content of resin (A) is usually 10 parts by weight to 80 parts by weight relative to 100 parts by weight of the total amount of resin (A) and resin (B) , Preferably 20 parts by weight to 75 parts by weight, and the content of resin (B) is usually 20 parts by weight to 90 parts by weight, preferably 25 parts by weight to 80 parts by weight.

In addition to resin (A) and resin (B), the resin composition system may contain rubber elastomer particles. As the rubber elastomer particles, commercially available rubber elastomer particles can be used, for example, the "PARALOID ^TM " EXL series sold by Dow Chemical, and the "KANE ACE (registered trademark)" series sold by Kaneka (Stock). "METABLEN" C series, E series, W series, S series, etc. sold by Mitsubishi Rayon (stock).

The particle size of the rubber elastomer particles is, for example, 50 nm to 0.8 μm, preferably 0.1 μm to 0.5 μm. When the particle diameter of the rubber elastomer particles is less than 50 nm, the fluidity of the resin composition is likely to decrease when the resin composition is processed into a film. When the particle size is larger than 0.8 μm, the internal haze of the thermoplastic resin composition tends to increase. The particle diameter of the rubber elastomer particles can be measured by the number average molecular weight by observation with an electron microscope.

Relative to 100 parts by weight of the total amount of resin (A) and resin (B), the content of rubber elastomer particles is usually 2 parts by weight to 50 parts by weight, preferably 5 parts by weight to 35 parts by weight.

The thermoplastic resin film of the present invention is based on the content (W _A ) of the methacrylate monomer unit in the resin (A), and the W _B /W _A of the resin (A) and the resin (B) is greater than 1 After the resin composition is prepared by the method, for example, as shown in Fig. 1, it can be manufactured by thinning the resin composition using a melt extrusion molding method. In addition, it can also be manufactured by thinning the resin composition using a solution casting film forming method, a hot pressing method, or the like. In particular, it is preferable to use a melt extrusion molding method to produce a thermoplastic resin film.

Hereinafter, the method of manufacturing the thermoplastic resin film of the present invention using the melt extrusion molding method will be further explained. Resin (A) and resin (B) are blended so that W _B /W _A becomes greater than 1, and other components described later are added as necessary to obtain a resin composition. Secondly, a uniaxial or biaxial extruder is used The obtained resin composition is melted and kneaded, and then the molten resin is continuously extruded from a T-mold into a film shape, and the surface is smooth on a pair of cooling rolls (first cooling roll and second cooling roll) In between, the extruded film-like molten resin is sandwiched, and further wound on the third cooling roll and shaped as necessary. By cooling, the elongated thermoplastic resin film can be obtained in an unstretched state. The blending method of resin (A), resin (B) and other components is not limited. It can be blended using well-known methods. High-speed mixers and Banbury mixers can be used, and single-shaft or double-shaft can also be used. Melt-kneading is performed by an extruder, and these may be combined and performed. In addition, the first cooling roll, the second cooling roll, and the third cooling roll may be composed of a metal roll or a metal elastic roll, or may be composed of a combination of a metal roll and a metal elastic roll.

When the thermoplastic resin film of the present invention contains resin (A) and resin (B), and further contains rubber elastomer particles, it can be prepared by blending resin (A), resin (B) and rubber elasticity. After the bulk particles are obtained to obtain the thermoplastic resin composition, it is manufactured by forming a thin film using the melt extrusion method in the same manner as described above. In addition, it can also be produced by a method of forming a thin film using a solution casting method, a hot pressing method, or the like. The melt extrusion molding method is preferred.

Hereinafter, when the thermoplastic resin film of the present invention contains resin (A) and resin (B), and further contains rubber elastomer particles, a melt extrusion method is used to produce the thermoplastic resin of the present invention The film method is further explained. Resin (A), resin (B) and rubber elastic single particles are blended in such a way that W _B /W _{A is} greater than 1, and other components described later are added as necessary to obtain a resin composition. Secondly, by uniaxial or biaxial The extruder melts and kneads the obtained resin composition, and then continuously extrudes the molten resin from the T-shaped mold into a film, and is placed on a pair of smooth cooling rolls (the first cooling roll and the second cooling roll). The extruded film-like molten resin is sandwiched between the cooling rolls, and is further wound on the third cooling roll and shaped as necessary. Cooling makes it possible to manufacture a long-form thermoplastic resin film in an unstretched state. The compounding method of resin (A), resin (B), rubber elastomer particles and other components is not limited, and it can be compounded using a well-known method. High-speed mixer and Banbury mixer can be used, or you can Melt kneading is carried out using a single-shaft or twin-shaft extruder, or a combination of these can be carried out. In addition, the first cooling roll, the second cooling roll, and the third cooling roll system may be composed of a metal roll or a metal elastic roll, or may be composed of a combination of a metal roll and a metal elastic roll.

The thermoplastic resin film of the present invention may contain other components other than resin (A) and resin (B). As other components, light diffusing agents, delustering agents, dyes, light stabilizers, ultraviolet absorbers, antioxidants, mold release agents, flame retardants, antistatic agents, and other resins (resin (A) and resin ( B) Other resins).

The thermoplastic film of the present invention preferably contains an ultraviolet absorber, and preferably contains an ultraviolet absorber having a maximum absorption at a wavelength of 200 to 320 nm (hereinafter referred to as ultraviolet absorber X) and an absorption at a wavelength of 320 to 400 nm. Ultraviolet absorber (hereinafter referred to as ultraviolet absorber Y).

Examples of the ultraviolet absorber X include triazine-based ultraviolet absorbers with maximum absorption at a wavelength of 200 to 320 nm, diphenyl ketone ultraviolet absorbers with maximum absorption at a wavelength of 200 to 320 nm, and absorption at a wavelength of 200 to 320 nm. Extreme benzotriazole UV absorption A benzoate-based ultraviolet absorber with a maximum absorption at a wavelength of 200 to 320nm and a cyanoacrylate-based ultraviolet absorber with a maximum absorption at a wavelength of 200 to 320nm.

Examples of ultraviolet absorbers X include 2,4-diphenyl-6-(2-hydroxy-4-methoxyphenyl)-1,3,5-triazine and 2,4-diphenyl -6-(2-hydroxy-4-ethoxyphenyl)-1,3,5-triazine, 2,4-diphenyl-(2-hydroxy-4-propoxyphenyl)-1, 3,5-triazine, 2,4-diphenyl-(2-hydroxy-4-butoxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2 -Hydroxy-4-butoxyphenyl)-1,3,5-triazine, 2,6-diphenyl-4-(2-hydroxy-4-hexyloxyphenyl)-1,3,5 -Triazine, 2,4-Diphenyl-6-(2-hydroxy-4-octyloxyphenyl)-1,3,5-triazine, 2,4-Diphenyl-6-(2- Hydroxy-4-dodecyloxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-benzyloxyphenyl)-1,3, 5-triazine, 2,4-bis(2,4-dimethylphenyl)-6-(2-hydroxy-4-N-octyloxyphenyl)-1,3,5-triazine, 2 -(4,6-Diphenyl-1,3,5-triazin-2-yl)-5-(2-(2-ethylhexyloxy)ethoxy)phenol, 2,4-di Hydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone , 2-hydroxy-4-octadecyloxy diphenyl ketone, 2,2'-dihydroxy-4-methoxy diphenyl ketone, 2,2'-dihydroxy-4,4'-dimethyl Oxydiphenyl ketone, 2,2',4,4'-tetrahydroxydiphenyl ketone, 2-(2-hydroxy-3,5-di-tertiary pentyl phenyl) benzotriazole, 3 ',5'-Di-tert-butyl-4'-hydroxybenzoic acid 2,4-Di-tert-butylphenyl ester, 3',5'-Di-tert-butyl-4'-hydroxybenzoic acid 2,6-Di-tert-butylphenyl ester, 3,5-di-tert-butyl-4-hydroxybenzoic acid n-hexadecyl ester, 3,5-di-tert-butyl-4-hydroxybenzoic acid N-octadecyl ester, 2-cyano-3,3-diphenyl acrylate 2-ethylhexyl and 2-cyano-3-(3,4-methylenedioxyphenyl) ethyl acrylate, etc.

Examples of the ultraviolet absorber Y include triazine-based ultraviolet absorbers having a maximum absorption at a wavelength of 320 to 400 nm, diphenylketone ultraviolet absorbers having a maximum absorption at a wavelength of 320 to 400 nm, and absorption at a wavelength of 320 to 400 nm. Very large benzotriazole-based ultraviolet absorber.

As the ultraviolet absorber Y, for example, 2,4,6-ginseng (2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3,5-triazine, 2, 2'- Dihydroxy-4-methoxydiphenyl ketone, 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-(2-hydroxy-3,5-di-tert-butylbenzene Yl)benzotriazole, 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)benzotriazole, 2-(2-hydroxy-3,5-di-tert-butyl Phenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3-(3,4,5,6-tetrahydrophthaliminomethyl)-5-methylphenyl)benzotriazole Azole, 2,2'-methylenebis(4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol), 2-( 2-Hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole and 2-(2-hydroxy-3,5-di-tert-pentylphenyl)-5- Chlorobenzotriazole and so on.

Two or more types of ultraviolet absorbers X may be used in combination, or two or more types of ultraviolet absorbers Y may be used in combination. The ultraviolet absorber X and the ultraviolet absorber Y having a similar structure can also be used in combination, and the ultraviolet absorber X and the ultraviolet absorber Y having a similar structure can also be used in combination. Formation caused by evaporate during film forming For the thermoplastic resin film with less pollution around the machine and excellent UV absorption capacity, the UV absorber that is easy to evaporate during melt extrusion and the UV absorber that is not easy to evaporate during melt extrusion It is better to use in combination.

The ultraviolet absorbers X and Y preferably have a molecular weight of 500 to 1,000, and more preferably 550 to 700. If the molecular weight of the ultraviolet absorbers X and Y is too small, they tend to evaporate during the formation of the polarizer protective film. When the molecular weight is too large, the compatibility with the thermoplastic resin is likely to decrease.

The molar absorption coefficients of the ultraviolet absorbers X and Y at absorbing maximum wavelengths are each 10L/mol. More than cm is better, 15L/mol. More than cm is better. Since the molar absorption coefficients of the ultraviolet absorbers X and Y at absorbing extremely large wavelengths are each within the above predetermined range, the polarizer protective film has more excellent ultraviolet absorption ability, and can reduce the amount of ultraviolet absorbers in the polarizer protective film. Content.

Commercially available ultraviolet absorbers can also be used. As a commercially available triazine-based ultraviolet absorber, for example, "Kemisorb 102" (2,4-bis(2,4-dimethylphenyl)-6-(2-hydroxy-) manufactured by CHEMPRO Chemicals Co., Ltd. 4-N-octyloxyphenyl)-1,3,5-triazine), "Adekastab LAF70" manufactured by ADEKA (stock) (2,4,6-see (2-hydroxy-4-hexoxy- 3-methylphenyl)-1,3,5-triazine), "Adekastab LA46" (2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5- (2-(2-ethylhexyloxy)ethoxy)phenol), and "TINUVIN 1577" (2,4-diphenyl-6-(2-hydroxy-4- Hexyloxyphenyl)-1,3,5-triazine) and the like.

Examples of commercially available benzotriazole-based ultraviolet absorbers include "Adekastab LA31" (2,2'-methylenebis(4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazole-2) manufactured by ADEKA Co., Ltd. -Yl)phenol), "Kemisorb279" (2,2'-methylenebis(4-(1,1,3,3-tetramethylbutyl)-6-(2H- Benzotriazol-2-yl)phenol), and "SUMISORB 200" (2-(2-hydroxy-5-methylphenyl)benzotriazole) from Sumika CHEMTEX (stock).

The glass transition temperature of the resin composition containing the resin (A) and the resin (B) is preferably 100°C or higher, more preferably 115°C or higher, and usually 180°C or lower. The glass transition temperature means that the glass transition intermediate temperature is calculated by differential scanning calorimetry in accordance with JIS K7121: 1987 at a heating rate of 10°C/min. When the glass transition temperature of the resin composition is lower than 100°C, when the thermoplastic film is used as a polarizer protective film, it is difficult to suppress the shrinkage of the polarizer, or the polarizer is deformed, or the polarizer is easily protected from the polarizer in a high temperature environment. The film peeling off.

The melt mass flow rate (MFR) of the resin composition at 230°C and 37.3N is preferably 0.8g/10min to 10g/10min, more preferably 0.9g/10min to 8g/10min, and 1.0g/10min to 1.0g/10min. 6g/10min is better. When the MFR is larger than this range, when the thermoplastic resin film is manufactured by melt extrusion molding, the stability of the discharge amount of the melted resin composition may be impaired. When the MFR is less than this range, when the thermoplastic resin film is manufactured by melt extrusion, the melted resin composition may not be uniformly expanded in the T-mold, resulting in accurate thickness of the thermoplastic resin film The situation is reduced. The MFR system can be measured in accordance with JIS K7210 under the conditions of a measurement temperature of 230°C and a load of 37.3N.

In addition, when the resin (A) further contains cyclic acid anhydride monomer units is used, in terms of suppressing the generation of bubbles due to cyclic acid anhydride monomer units during melt kneading, the MFR is 1.2 g/10 min or more good.

The thickness of the thermoplastic resin film of the present invention is preferably 10 μm to 1000 μm, more preferably 20 μm to 500 μm, and even more preferably 20 μm to 300 μm.

For the thermoplastic resin film of the present invention, the thickness of the converted film is 40μm and the light transmittance at a wavelength of 260nm is preferably 2% or less, and the thickness of the converted film is 40μm and the light transmittance at a wavelength of 380nm is preferably 5% or less .

The thermoplastic resin film of the present invention is preferably a film with a single-layer structure, and it may be a film with a multilayer structure of two or more layers as long as the effects of the present invention are not impaired. When the thermoplastic resin film has a multilayer structure, each layer may be formed of a resin composition of the same composition, or may be formed of a resin composition of different composition. The so-called resin composition of different composition includes any of the following situations: the type of resin contained is different; the type of resin is the same but the content of each resin is different; and the type and content of the resin is the same but other components are different Wait.

[The stretched film of the present invention]

The stretched film of the present invention is a film obtained by stretching the above-mentioned thermoplastic resin film of the present invention. The stretched film of the present invention is excellent in heat resistance like the thermoplastic resin film of the present invention, and because it is less likely to shrink in a high temperature environment and can be stretched further, it also has excellent The mechanical strength.

As a method of stretching the thermoplastic resin film of the present invention, a uniaxial stretching method and a biaxial stretching method can be cited. Especially the method of biaxial extension is preferred. As the method of biaxial stretching, successive biaxial stretching method and simultaneous biaxial stretching method can be cited. Examples of the extending direction include the mechanical flow direction of the thermoplastic resin film, and also include a direction orthogonal to the mechanical flow direction and a direction oblique to the mechanical flow direction. The extension ratio is preferably 1.1 to 3 times. In this specification, the mechanical flow direction is defined as the longitudinal direction and the longitudinal extension is defined as the longitudinal extension; the direction orthogonal to the mechanical flow direction is defined as the lateral direction and the lateral extension is defined as the lateral extension. In addition, the “machine flow direction” refers to the direction in which the resin composition is transported while forming a film from a molten state into a film when manufacturing a long-form thermoplastic resin film by melt extrusion molding.

The stretched film of the present invention may also be subjected to surface treatment. Examples of the surface treatment include hard coating treatment, anti-glare treatment, and anti-fouling treatment.

[Polarizer protective film]

Either the thermoplastic resin film of the present invention and the stretched film of the present invention are suitable as a polarizer protective film. The polarizer protective film is a film that is arranged on one side of the polarizer to protect the polarizer. The thermoplastic resin film of the present invention and the stretched film of the present invention are in addition to the polarizer protective film, but also can be laminated on windows and carport roofing materials such as building lighting members, car windows and other vehicle lighting Components, greenhouses and other agricultural lighting components, lighting components, front-end films and other display structures In addition, it can also be laminated on the housing of home appliances, vehicle interior decoration members, interior building materials, wallpaper, cosmetic panels, front doors, window frames, skirting boards, etc. as decorative films.

[Polarizer]

The polarizer of the present invention is a polarizer in which the polarizer protective film of the present invention is arranged on at least one side of the polarizer. The polarizer protective film and the polarizer are preferably bonded together. As a polarizer, a well-known polarizer can be mentioned. The thickness of the polarizer is usually 5 μm to 40 μm.

When a polarizer protective film is placed on one side of the polarizer, a transparent resin film can be placed on the other side. The transparent resin film and the polarizer are preferably bonded together. Examples of transparent resin films include cellulose triacetate film, polycarbonate film, polyethylene terephthalate film, acrylic resin film, laminated film of acrylic resin and polycarbonate resin, and olefin resin film .

The polarizer protective film of the present invention and the polarizer are preferably bonded together using an adhesive. Before bonding, it is preferable to perform corona discharge treatment, plasma irradiation treatment, electron beam irradiation treatment, or other surface activation treatment on at least one of the bonding surfaces in advance. The polarizer protective film of the present invention contains methacrylate monomer units. Compared with the polarizer protective film composed of a resin that does not contain aromatic vinyl monomer units, it has Excellent bonding strength.

The adhesive system can be arbitrarily selected and used from those exhibiting adhesive force to each member. Typically, water-based adhesives, namely It is obtained by dissolving the adhesive component in water or dispersing the adhesive component in water; an active energy ray curable adhesive containing a component that is hardened by irradiation with active energy rays. In particular, from the viewpoint of productivity, an active energy ray curable adhesive is preferable.

As the water-based adhesive, a composition using polyvinyl alcohol-based resin and urethane resin as main components is preferred. When using polyvinyl alcohol-based resin as the main component of the water-based adhesive, as the polyvinyl alcohol-based resin, there can be exemplified partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol, and carboxy-modified polyvinyl alcohol, acetyl acetone. Modified polyvinyl alcohol based on modified polyvinyl alcohol, methylol modified polyvinyl alcohol, modified polyvinyl alcohol based resin of amine modified polyvinyl alcohol, etc. When a polyvinyl alcohol-based resin is used as an adhesive component, the adhesive is usually prepared as an aqueous solution of the polyvinyl alcohol-based resin. With respect to 100 parts by weight of water, the concentration of the polyvinyl alcohol-based resin in the adhesive aqueous solution is preferably 1 part by weight to 10 parts by weight, more preferably 1 part by weight to 5 parts by weight.

A water-based adhesive that uses polyvinyl alcohol-based resin as the main component is preferably added with curable components such as glyoxal, water-soluble epoxy resin, or crosslinking agent in order to improve adhesiveness. As water-soluble epoxy resins, for example, polyalkylene polyamines such as diethylenetriamine or triethylenetetramine are reacted with epichlorohydrin to polyalkylene polyamines such as adipic acid and polyamide polyamines are obtained. Amine, polyamide polyamine epoxy resin obtained by reaction, etc. As the polyamide polyamine epoxy resin system, commercially available products can be used, for example, "Sumirez Resin 650" and "Sumirez Resin 675" manufactured by Taoka Chemical Co., Ltd., and "WS-525" manufactured by Starlight PMC Co., Ltd. "Wait. Relative to 100 parts by weight of polyvinyl alcohol resin, The addition amount of the hardening components or crosslinking agents is preferably 1 part by weight to 100 parts by weight, more preferably 1 part by weight to 50 parts by weight. When the addition amount is small, the adhesion improvement effect becomes small. On the other hand, when the addition amount is large, the adhesive layer may be fragile.

When using urethane resin as the main component of the water-based adhesive, examples of suitable adhesive compositions include polyester-based ionomer type urethane resins and compounds having glycidyloxy groups The mixture. The polyester-based ionic polymer urethane resin referred to herein refers to a urethane resin having a polyester skeleton in which a small amount of ionic components (hydrophilic components) are introduced. Since no emulsifier is used, it is directly emulsified in water to form an emulsified liquid. Therefore, the ionomer urethane resin system is preferably used as an aqueous adhesive.

When an activated energy ray curable adhesive is used, the component that is configured to be cured by active energy ray irradiation (hereinafter, sometimes referred to as "curable component") includes epoxy compounds and oxygen heterocycles. Butane compounds, acrylic compounds, etc. When using cationic polymerizable compounds such as epoxy compounds and oxetane compounds, a cationic polymerization initiator can be formulated. In addition, when a radical polymerizable compound such as an acrylic compound is used, a radical polymerization initiator can be formulated. In particular, it is preferable to use an epoxy compound as one of the curing components, and it is more preferable to use an alicyclic epoxy compound in which an epoxy group is directly bonded to a saturated carbocyclic ring as one of the curing components. In addition, an oxetane compound may be used in combination.

As the epoxy compound, commercially available products can also be used, for example, the "Epikote" series manufactured by Mitsubishi Chemical Corporation, and those manufactured by DIC Corporation "Epiclon" series, "EpoTohto" series manufactured by Nippon Steel & Sumitomo Metal Co., Ltd., "ADEKA RESIN" series manufactured by ADEKA Co., Ltd., "DENACOL" series manufactured by NAGASE CHEMTEX Co., Ltd., "Dow" manufactured by Dow Chemical Co., Ltd. Epoxy" series, "TEPIC" manufactured by Nissan Chemical Industry Co., Ltd., etc.

As the alicyclic epoxy compound system in which the epoxy group is directly bonded to the saturated carbocyclic ring, commercially available products can be used. Examples include the "CELLOXIDE" series and "CYCLOMER" series manufactured by Daicel Chemical Industry Co., Ltd., and the Dow Chemical Company. "Cyracure" series etc.

As the oxetane compound system, commercially available products can be used, and examples include the "ARON OXETANE" series manufactured by Toagosei Co., Ltd., and the "ETERNACOLL" series manufactured by Ube Industries Co., Ltd., and the like.

As the cationic polymerization initiator system, commercially available products can be used, for example, "KAYACURE" series manufactured by Nippon Kayaku Co., Ltd., "Cyracure" series manufactured by Dow Chemical Co., Ltd., and photoacid manufactured by SAN-APRO Co., Ltd. "CPI" series of generators, "TAZ", "BBI" and "DTS" of photoacid generators manufactured by MIDORI Chemical Co., Ltd., "ADEKA OPTOMER" series manufactured by ADEKA Co., Ltd., "RHODORSIL" manufactured by Rhodia "Series etc.

The active energy ray-curable adhesive can contain a photosensitizer as necessary. By using a photosensitizer, the reactivity can be improved and the mechanical strength and adhesive strength of the hardened layer can be further improved. Examples of photosensitizers include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, anthracene compounds, halogen compounds, and photoreducible dyes.

The active energy ray curable adhesive can be formulated with various additives without impairing its adhesiveness. Examples of additives include ion scavengers, antioxidants, chain transfer agents, tackifiers, thermoplastic resins, fillers, flow regulators, plasticizers, defoamers, and the like. In addition, it is also possible to formulate a curable component that is cured by polymerization with cations as a separate reaction mechanism within a range that does not impair its adhesiveness.

The active energy ray curable adhesive can be of the same composition or different compositions. The active energy ray used to harden the two is preferably irradiated at the same time.

Examples of active energy rays include X-rays, ultraviolet rays, and visible rays. In particular, from the viewpoint of ease of use, ease of preparation of the active energy ray curable adhesive, stability, and curing performance, ultraviolet rays are preferred. Examples of the ultraviolet light source include a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excited mercury lamp, and a metal halide lamp.

The active energy ray curable adhesive is coated on the polarizer or the polarizer protective film of the present invention to form a coating film, and the polarizer and the polarizer protective film of the present invention are laminated through the formed coating film, and by The active energy ray is irradiated to harden the active energy ray curable resin, and the polarizer and the protective film of the present invention are adhered to obtain the polarizing plate of the present invention.

The thickness of the adhesive layer obtained by using the active energy ray curable adhesive is preferably 1 to 50 μm, and more preferably 1 to 10 μm. The thickness of the adhesive layer can be adjusted by the thickness of the coating film forming the polarizer or the polarizer protective film of the present invention.

The polarizing plate of the present invention can be bonded to a liquid crystal cell as a liquid crystal panel used in a liquid crystal display device. The polarizing plate and the liquid crystal cell system are preferably attached through the adhesive layer using an adhesive. Generally, the adhesive layer is formed using an acrylic adhesive, wherein the acrylic adhesive is composed of acrylic resin as the main component and copolymerized with functional group-containing acrylic monomers as the adhesive component. A liquid crystal panel formed by bonding a polarizing plate to a liquid crystal cell through an adhesive layer can be used in a liquid crystal display device.

Since the polarizer protective film of the polarizer of the present invention is composed of the thermoplastic resin of the present invention or the stretched film of the present invention, it has excellent heat resistance and can suppress the shrinkage of the polarizer even in a high temperature environment.

[Example]

Hereinafter, the present invention will be explained concretely with examples.

The extrusion device used in the Examples and Comparative Examples is the device shown in Fig. 1, and its structure is as follows.

Extruder: Extruder with a screw diameter of 65mm, a single shaft, and an exhaust hole [manufactured by Toshiba Machine Co., Ltd.].

T-type mold: a multi-manifold mold with a width of 800 mm and a lip interval of 1 mm [made by Hitachi Zosen Co., Ltd.].

The first cooling roll: metal elastic roll

The second cooling roll: metal roll

The third cooling roll: metal roll

The metal elastic roller is a metal elastic roller with an outer diameter of 250mm, It is to cover the outer circumference of the roller made of stainless steel. A stainless steel film with a thickness of 2mm with a mirror-finished surface is arranged so that the mirror-finished surface becomes the surface of the roller. The fluid is composed of heat medium oil. It is sealed between the roller and the metallic film. The metal roller is a spiral roller with an outer diameter of 250mm, which is composed of stainless steel whose surface is mirror-finished.

[Thermoplastic resin]

The thermoplastic resins used in Examples 1 to 6 and Comparative Examples 1 to 5 are disclosed below. The weight average molecular weight Mw and number average molecular weight Mn of the respective resins are determined by gel permeation chromatography (GPC) measurement. In addition, the weight average molecular weight Mw and the number average molecular weight Mn of the resin A1, the resin A2, and the resin C are calculated in terms of polystyrene. The weight average molecular weight Mw and the number average molecular weight Mn of the resin B1 are calculated in terms of polymethyl methacrylate.

Resin A1: A resin composed of methyl methacrylate monomer units, styrene monomer units and maleic anhydride monomer units, and used by combining methyl methacrylate, styrene and maleic acid Prepared by acid anhydride copolymerization.

Relative to 100% by weight of all monomer units constituting resin A1, the content of methyl methacrylate monomer units is 20% by weight, and the content of styrene monomer units is 65% by weight, maleic anhydride The content ratio of the monomer unit is 15% by weight.

In addition, the weight average molecular weight (Mw) of the resin A1 was 150,000, the number average molecular weight (Mn) was 68,000, and the Mw/Mn was 2.2.

Resin A2: A resin composed of methyl methacrylate monomer units, styrene monomer units and maleic anhydride monomer units, and used by combining methyl methacrylate, styrene and maleic acid Prepared by acid anhydride copolymerization.

With respect to the total of 100% by weight of all monomer units constituting resin A2, the content of methyl methacrylate monomer units is 26% by weight, and the content of styrene monomer units is 57% by weight, maleic anhydride The content ratio of the monomer unit is 17% by weight.

The weight average molecular weight (Mw) of the resin A2 was 150,000, the number average molecular weight (Mn) was 66,000, and the Mw/Mn was 2.3.

Resin C: A resin composed of methyl methacrylate monomer units, styrene monomer units and maleic anhydride monomer units, and used by combining methyl methacrylate, styrene and maleic anhydride Prepared by acid anhydride copolymerization.

With respect to 100% by weight of all monomer units constituting resin C, the content of methyl methacrylate monomer units is 39% by weight, and the content of styrene monomer units is 47% by weight, maleic anhydride The content ratio of the monomer unit is 14% by weight.

The weight average molecular weight (Mw) of the resin C is 220,000, the number average molecular weight (Mn) is 83,000, and the Mw/Mn is 2.6.

Resin B1: A resin composed of methyl methacrylate monomer units and methyl acrylate monomer units, and using 100% by weight relative to the total of all monomer units constituting resin B1, the methyl methacrylate and acrylic Methyl ester, the content ratio of methyl methacrylate monomer unit becomes 97% by weight and 3% by weight of methyl acrylate monomer units are prepared and polymerized. After polymerization, the UV absorber "SUMISORB 200" (manufactured by Sumika CHEMTEX) will have a large absorption at 300nm and 342nm. It is prepared so that the concentration is 120 ppm, and the obtained resin composition is melt-kneaded by a biaxial extruder.

The weight average molecular weight (Mw) of the resin B1 is 160,000, the number average molecular weight (Mn) is 85,000, and the Mw/Mn is 1.9.

[Ultraviolet absorber]

As the ultraviolet absorber, X1, Y1, Y2 disclosed below are used, and the ultraviolet absorber X1: ultraviolet absorber Y1: ultraviolet absorber Y2 (weight ratio) is mixed and used so that it becomes 0.7:0.6:1.2.

UV absorber X1: UV absorber "Kemisorb102" manufactured by CHEMIPRO Chemicals (Stock) (Maximum absorption: wavelength 280nm, molar absorption coefficient: 68.3L/mol.cm, weight average molecular weight: 508.9, triazine-based UV absorber)

UV absorber Y1: UV absorber "LAF70" manufactured by ADEKA (stock) (maximum absorption: wavelength 356nm, molar absorption coefficient: 65.7L/mol.cm, weight average molecular weight: 699.9, triazine-based UV absorber)

UV absorber Y2: UV absorber "Adekastab LA31" manufactured by ADEKA (stock) (maximum absorption: wavelength 350nm, molar absorption coefficient: 18.0L/mol.cm, weight average molecular weight: 658, benzotriazole (UV absorber)

Examples 1 to 6 and Comparative Examples 1 to 5 [Manufacturing of Thermoplastic Resin Film]

The extruder, T-shaped mold, and the first to third cooling rolls are arranged in the manner shown in Figure 1. Next, the resin composition obtained by mixing resin A1, resin A2 or resin C, resin B1, and ultraviolet absorber at the ratio shown in Table 1 was melt-kneaded by an extruder, and each was supplied to a set temperature of 260 ℃ T-shaped mold.

Between the first cooling roll and the second cooling roll arranged opposite, the film-like molten resin extruded from the T-shaped mold is sandwiched and wound on the third cooling roll to form. After cooling, a thermoplastic resin film with a thickness of 120 μm was obtained.

In addition, the surface temperature of the first cooling roll was 80°C, the surface temperature of the second cooling roll was 80°C, and the surface temperature of the third cooling roll was 100°C. These temperatures are the actual measured values of the surface temperature of each cooling roll.

Moreover, relative to 100 parts by weight of the total amount of resin A2 and resin B1 in Example 6, the usage amount of resin A2, resin B1, and ultraviolet absorber is approximately 25 parts by weight of resin A2. The usage amount is about 75 parts by weight, and the usage amount of the ultraviolet absorber is about 2.5 parts by weight.

The MFR of each resin composition was measured in accordance with JIS K7210 (measurement temperature 230°C, load 37.3N). In addition, the glass transition temperature of each resin composition was measured. The results obtained are shown in Table 2.

In order to evaluate the impact resistance of each thermoplastic resin film obtained, the following method was used to measure the Chabaite impact strength; to evaluate the surface hardness, the following method was used to measure the pencil hardness. degree. The results are shown in Table 3.

<Chabaite impact strength>

According to JIS K7111-1, the obtained thermoplastic resin film was cut into a width of 10 mm and measured.

<Pencil Hardness>

Measure according to JIS K5600.

[Manufacturing of Stretch Film]

Each of the obtained thermoplastic resin films was biaxially stretched to produce a stretched film. First, each thermoplastic resin film is stretched longitudinally through two pairs of nip rollers provided before and after the hot air circulation furnace. The hot-air circulating furnace uses a furnace that can be divided into four zones with 1m intervals and set the temperature. The first zone on the inlet side of the furnace is set to room temperature, the second zone is set to the same temperature as the glass transition temperature (Tg) of the resin composition used in the production of the thermoplastic resin film, and the next third zone The zone and the fourth zone on the outlet side are set to a temperature 10°C higher than Tg. By setting the film speed through the nip roll on the inlet side to 2mm/min, and the film speed through the nip roll on the outlet side to 4.4mm/min, the longitudinal stretch magnification is 2.2 times. film.

Next, the manufactured longitudinally stretched film is cut so that the longitudinal length becomes 1m to obtain a longitudinally stretched film with a longitudinal length of 1m, and the longitudinally stretched film with a longitudinal length of 1m is introduced into the transverse tenter stretcher for transverse stretch extend. The lateral stretching was performed in a hot-air circulation furnace with a length of 4m, and the temperature in the furnace was set to a temperature higher than Tg by 10°C. Through the furnace The speed inside is set to 1mm/min, and the extension ratio is set to 2 times. As described above, a biaxially stretched film having a longitudinal stretch ratio of 2.2 times and a transverse stretch ratio of 2 times was obtained. The thickness of the obtained biaxially stretched film was 40 μm.

<Operability>

The following method was used to evaluate the workability during stretching of the thermoplastic film used for manufacturing the stretched film.

The longitudinally stretched film obtained by longitudinally stretching the thermoplastic resin film was cut to obtain 10 longitudinally stretched films having a longitudinal length of 1 m. With respect to the obtained 10 longitudinally stretched films, each was stretched laterally to obtain 10 biaxially stretched films. In this longitudinal stretching and lateral stretching, when the number of films broken by stretching is 0, it is judged that the handleability is good and the evaluation is ○, and when one or more films are broken, the handling is judged to be poor and the evaluation is ×. The evaluation results are shown in Table 3.

[Manufacturing of Polarizer]

A polyvinyl alcohol film with an average degree of polymerization of about 2,400, a degree of saponification of 99.9 mol% or more, and a thickness of 75 μm is immersed in pure water at 30°C, and then immersed in iodine/potassium iodide/water at a weight ratio of 0.02/2/100 at 30°C The aqueous solution. Subsequently, it was further immersed in an aqueous solution with a weight ratio of potassium iodide/boric acid/water of 12/5/100 at 56.5°C. After washing the immersed film with pure water at 8°C, it was dried at 65°C to obtain a polarizer with iodine in the polyvinyl alcohol adsorption and alignment. The stretching system is mainly performed by iodine dyeing and boric acid treatment steps, and the total stretching magnification is 5.3 times, and the thickness of the obtained polarizer is 27 μm.

[Manufacturing of Polarizing Plate]

After corona treatment is applied to the biaxially stretched film as a protective film to the respective bonding surfaces, an ultraviolet curing adhesive ("ARONIX" manufactured by Toagosei Co., Ltd.) is applied and bonded by a bonding roller On both sides of the obtained polarizer. Subsequently, ultraviolet rays are irradiated and the aforementioned adhesive is cured to obtain a polarizing plate. In addition, the ultraviolet irradiation was performed so that the cumulative light intensity in the wavelength range from 260 nm to 320 nm became 200 mJ/cm ² .

<Evaluation of mechanical strength under high temperature environment>

In order to evaluate the mechanical strength of the biaxially stretched film in a high temperature environment, the following method was used to measure the high temperature tensile modulus of the biaxially stretched film at 80°C. The higher the value, the higher the intensity of the shrinkage suppression of the polarizing film under a high temperature environment when attached to the polarizer, which is better.

The biaxially stretched film was cut into a rectangle with a longitudinal direction of 120 mm and a lateral direction of 25 mm with the longitudinal direction as the long side, the chuck distance was set to 90 mm, and the longitudinal stretching speed was 5 mm/min, and a tensile test was performed at 80°C. In the region where the tensile strength is from 3 MPa to 6 MPa, the high-temperature tensile modulus of elasticity is calculated from the slope of the stress-strain curve. The calculated results are shown in Table 3.

<Evaluation of light transmittance>

The spectrophotometer U-4100 manufactured by Hitachi High-Tech Fielding was used to measure the light transmittance of the biaxially stretched film at a wavelength of 260nm and the light transmittance at a wavelength of 380nm. The results are shown in Table 3.

<Evaluation of shrinkage rate of polarizing plate>

The direction parallel to the extending direction of the polarizing film of the polarizing plate is set to MD, and the direction perpendicular to the extending direction of the polarizing film is set to TD. From the produced polarizing plate, cut out the length of 100mm in MD direction and TD direction. Polarizing plate with a length of 100mm. The cut out polarizer was set in an oven set at 80°C and kept for 250 hours. The polarizing plate was taken out, and the length in the MD direction and the length in the TD direction were measured using a vernier, and the shrinkage rates in the MD and TD directions were calculated according to the following formula. The results are shown in Table 4.

Shrinkage rate (%)=100×{100-(length after heating at 80℃ (mm))}/100

<Evaluation of the adhesion strength of the polarizing plate>

The method shown below was used to evaluate the peel strength between the polarizing film and the protective film in the polarizing plate.

After leaving the produced polarizing plate for 300 hours, it was cut into a rectangle with a size of 200 mm×25 mm. An acrylic adhesive layer was provided on the surface of one protective film, and the adhesive layer was attached to the glass plate. Put the blade of the cutter between the protective film provided with the adhesive layer and the polarizing film, peel off 30 mm from the end in the length direction, and grasp the peeled part using the claw part of the testing machine. The test piece in this state is moved on the gripper in an environment with a temperature of 23°C and a relative humidity of 55% in accordance with JIS K6854-2: 1999 "Adhesive-Peeling Adhesion Strength Test Method-Part 2: 180° Peeling" Perform a 180-degree peel test at a speed of 300 mm/min, remove 30 mm of the claw part, and obtain an average peel force in a length range of 170 mm. Display the results in the table 5.

[Thermoplastic resin]

重量平均分子量Mw及數量平均分子量Mn係以聚苯乙烯換算而求取。樹脂B2的重量平均分子量Mw及數量平均分子量Mn係以聚甲基丙烯酸甲酯換算而求取。 Hereinafter, the thermoplastic resins used in Example 7 to Example 11 and Comparative Example 6 to Comparative Example 8 are disclosed. The weight average molecular weight Mw and number average molecular weight Mn of the respective resins are determined by gel permeation chromatography (GPC) measurement. Also, resin A3 and resin A4

The weight average molecular weight Mw and the number average molecular weight Mn are calculated in terms of polystyrene. The weight average molecular weight Mw and the number average molecular weight Mn of the resin B2 are calculated in terms of polymethyl methacrylate.

Resin A1: Use the same resin A1 used in Example 1 to Example 3.

Resin A3: A resin composed of methyl methacrylate monomer units, styrene monomer units, and maleic anhydride monomer units. It is used by combining methyl methacrylate, styrene and maleic anhydride Prepared by copolymerization.

With respect to the total of 100% by weight of all monomer units constituting resin A3, the content of methyl methacrylate monomer units is 21% by weight, and the content of styrene monomer units is 57% by weight, maleic anhydride The content ratio of the monomer unit is 22% by weight.

The weight average molecular weight (Mw) of the resin A3 was 193,000, the number average molecular weight (Mn) was 88,000, and the Mw/Mn was 2.2.

Resin A4: A resin composed of methyl methacrylate monomer units, styrene monomer units, and maleic anhydride monomer units. It is used by combining methyl methacrylate, styrene and maleic anhydride Prepared by copolymerization.

With respect to 100% by weight of all monomer units constituting resin A4, the content of methyl methacrylate monomer units is 21% by weight, and the content of styrene monomer units is 57% by weight, maleic anhydride The content ratio of the monomer unit is 22% by weight.

The weight average molecular weight (Mw) of the resin A4 was 127,000, the number average molecular weight (Mn) was 58,000, and the Mw/Mn was 2.19.

Resin B1: The same resin B1 used in Example 1 to Example 6, and Comparative Example 3 to Comparative Example 5 was used.

Resin B2: A resin composed of methyl methacrylate monomer units and methyl acrylate monomer units, and using 100% by weight relative to the total of all monomer units constituting resin B2, the methyl methacrylate and acrylic Methyl methacrylate is prepared so that the content ratio of methyl methacrylate monomer units becomes 99% by weight and the content ratio of methyl acrylate monomer units becomes 1% by weight, and after polymerization, it will have an absorption maximum at 300nm and 342nm. The ultraviolet absorber "SUMISORB 200" is formulated to have a concentration of 100 ppm, and the obtained resin composition is melt-kneaded by a biaxial extruder.

The weight average molecular weight (Mw) of resin B2 is 101,000 and the number is average The molecular weight (Mn) is 58,000, and the Mw/Mn is 1.8.

[Rubber elastomer particles]

As the rubber elastic body particles, the following rubber 1 and rubber 2 were used.

Rubber 1: "PARALOID ^TM EXL-2678" (butadiene rubber particles, powder form) manufactured by Dow Chemical Japan Co., Ltd. was used. The rubber 1 has a refractive index of 1.516 and a particle size of 200 nm.

Rubber 2: KANE ACE M732 (butadiene rubber, powdered) manufactured by Kaneka Co., Ltd. was used. The rubber 2 has a refractive index of 1.515 and a particle size of 130 to 180 nm.

Examples 7 to 11 and Comparative Examples 6 to 8 [Manufacturing of Thermoplastic Resin Film]

The resin A1, the resin A2, the resin A3, the resin A4, the resin B1, the resin B2, the rubber 1, the rubber 2, and the ultraviolet absorber were mixed in the ratio shown in Table 6 to obtain a resin composition. In addition, only Y2 [Adekastab LA31] is used for the ultraviolet absorber system. The obtained resin composition was obtained in the same manner as in Examples 1 to 6 and Comparative Examples 1 to 5 by using the extruder shown in Figure 1 using a T-shaped mold and the first to third cooling rolls Thermoplastic resin film. At this time, the thickness of the thermoplastic resin film is as shown in Table 8.

The results of measuring the MFR and glass transition temperature of the respective resin compositions are shown in Table 7, and the Chabait impact strength of the resulting thermoplastic resin film is shown in Table 8. In addition, the folding and bending properties of the obtained thermoplastic resin film are obtained by cutting a sample of the film into 10 mm × 50 mm When the film is folded and bent in half in the longitudinal direction without breaking, it is rated as "○", and when the film is broken, it is rated as "×". The results are shown in Table 8.

<Evaluation of mechanical strength under high temperature environment 2>

As a second method for evaluating the mechanical strength of the thermoplastic resin film in a high temperature environment, the following method is used to measure the high temperature tensile modulus of the thermoplastic resin film at 80°C.

The thermoplastic resin film was cut into a rectangle with a length of 100 mm and a width of 25 mm with the extrusion direction as the long side. The chuck distance was set to 50 mm and the longitudinal stretching speed was 1 mm/min. The tensile test was performed at 80°C. In the region where the tensile strength is from 3 MPa to 6 MPa, the high-temperature tensile modulus of elasticity is calculated from the slope of the stress-strain curve. The calculated results are shown in Table 8.

<Evaluation of light transmittance 2>

As a second method for evaluating the light transmittance of the thermoplastic resin film, a spectrophotometer UV-2450 manufactured by Shimadzu Corporation was used to measure the light transmittance at a wavelength of 260 nm and the light transmittance at a wavelength of 380 nm. The results are shown in Table 8.

[Manufacturing of Stretch Film]

The thermoplastic resin films obtained in Examples 7 and 8 were each subjected to biaxial stretching under the same conditions as in Examples 1 to 6 and Comparative Examples 1 to 5 to produce stretched films. The thickness of the obtained biaxially stretched film was 20 μm. The operability of the thermoplastic resin films of Examples 7 and 8 is either All are good. As a result of measuring the high-temperature tensile elastic modulus of the stretched film after stretching using the same method as the thermoplastic resin film before stretching, the stretched film of Example 7 was 2090 MPa, and the stretched film of Example 8 was 1869 MPa.

[Manufacturing of Polarizer 2]

The polarizer 2 was produced by the same method as the polarizer 1 except that the thickness of the polyvinyl alcohol film was changed to 60 μm and the total stretching ratio was changed to 5.6 times. The thickness of the obtained polarizer 2 was 22 μm.

[Manufacturing of Polarizing Plate]

On one side of the polarizer 2, the thermoplastic resin films of Examples 7 to 11 and Comparative Examples 6 to 8 were subjected to corona treatment on their bonding surfaces, and then coated with an ultraviolet curing adhesive (manufactured by Toagosei Co., Ltd.) "ARONIX"), and on the other side of the polarizer 2, a biaxially stretched product of cycloolefin resin and a retardation film that has been corona treated on the bonding surface, and coated with epoxy compound as the main component Another ultraviolet curable adhesive is bonded by a thermoplastic resin film/polarizer/retardation film. Subsequently, ultraviolet rays are irradiated to harden the aforementioned adhesive to obtain a polarizing plate. In addition, ultraviolet irradiation was performed so that the cumulative light intensity in the wavelength region of 260 nm to 320 nm became 200 mJ/cm ² .

<Evaluation of shrinkage rate of polarizing plate 2>

Parallel to the direction of extension of the polarizing film The direction is MD, the direction perpendicular to the extending direction of the polarizing film is TD, and a polarizing plate with a length of 100 mm in the MD direction and 100 mm in the TD direction is cut from the manufactured polarizing plate. The cut out polarizing plate was put into an oven at 80°C and kept for 250 hours. The dimensions before and after being put into the oven were measured using a two-dimensional size measuring device "NEXIV VMR-12072" manufactured by Nikon Corporation. And let the value calculated|required according to the following formula be a shrinkage rate (%). The measurement results are shown in Table 9.

In this table 6, the usage amount of resin A1, resin A2, resin A3, resin A4, resin B1, resin B2, rubber 1, rubber 2, and ultraviolet absorber (Y2) are expressed in "parts by weight". Express the unit as "(parts)".

[Industrial availability]

The thermoplastic resin film of the present invention has excellent heat resistance and is not easy to shrink in a high temperature environment, and is not easy to break due to stretching, so the stretched film formed by the stretch can be used as a protective film for a polarizer.

1‧‧‧Extrusion machine

2‧‧‧Plastic mold

3‧‧‧Film-like molten resin

4‧‧‧Cooling device

5‧‧‧The first cooling roll

6‧‧‧Second cooling roll

7‧‧‧The third cooling roll

A‧‧‧Thermoplastic resin film

Claims (6)

A thermoplastic resin film, which is composed of a resin composition containing resin (A) and resin (B), wherein the resin (A) contains methacrylate monomer units, aromatic vinyl monomer units and Cyclic acid anhydride monomer units; the resin (B) contains methacrylate monomer units and no aromatic vinyl monomer units; relative to 100% by weight of all monomer units constituting the resin (A), the resin ( A) A resin with an aromatic vinyl monomer unit content ratio of 50% by weight or more, relative to 100% by weight of all monomer units constituting the resin (B), the resin (B) is a methacrylate monomer unit For resins with a content ratio of 50% by weight or more, the ratio (W _B /W _A ) of the weight (W _B ) of the resin ( _B ) to the content (W _A ) of the methacrylate monomer unit in the resin ( _A ) is Greater than 1. The thermoplastic resin film described in the first item of the patent application, wherein the aforementioned resin composition system further contains rubber elastomer particles. The thermoplastic resin film described in item 1 or 2 of the scope of patent application, wherein the melt mass flow rate of the aforementioned resin composition is 1.2 g/10 min or more. A stretched film obtained by stretching the thermoplastic resin film described in any one of items 1 to 3 in the scope of the patent application. A polarizer protective film is composed of the thermoplastic resin film described in any one of items 1 to 3 of the scope of patent application or the stretched film described in item 4 of the scope of patent application. A polarizer is provided with the polarizer protective film described in item 5 of the scope of patent application on at least one side of the polarizer.

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