TWI648163B - Polarizer protective film and polarizer - Google Patents

Abstract

An object of the present invention is to provide a polarizer protective film that has excellent ultraviolet absorption energy and is disposed on at least one side of a polarizer to form a polarizer, and the polarizer is not easily viewed as yellow.

The solution of the present invention is a polarizer protective film, which comprises: an ultraviolet absorber A having a maximum absorption at a wavelength of 200 to 300 nm, an ultraviolet absorber B having a maximum absorption at a wavelength of 320 to 400 nm, and a polarizer protection of a thermoplastic resin. The thin film has a light transmittance of 3% or less at a wavelength of 260 nm, a light transmittance of 5% or less at a wavelength of 380 nm, and a value of b * of 0.50 or less.

Description

Polarizer protective film and polarizer

The invention relates to a polarizer protective film, and a polarizing plate having the polarizer protective film and a polarizer.

In recent years, light-weight and thin liquid crystal display devices, which have low power consumption and can operate at low voltage, are widely used in information display devices such as mobile phones, portable information terminals, computer monitors, and televisions.

In a liquid crystal display device, a polarizing plate must be provided. The polarizing plate is usually a polarizer protective film that is disposed on at least one side of a polarizer made of a dichroic pigment adsorbed and aligned on a polyvinyl alcohol-based resin film to protect the polarizer.

The polarizer protective film preferably has excellent ultraviolet absorption energy in order to prevent the polarizer from being deteriorated by the influence of ultraviolet rays. Therefore, Patent Document 1 discloses a product containing an acrylic resin, a triazine-based ultraviolet absorber, and a triazole-based ultraviolet absorber as a polarizer protective film having ultraviolet absorbing energy.

[Prior technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Application Publication No. 2012-3269

However, in Patent Document 1, the absorption energy with respect to ultraviolet rays having a wavelength of 380 nm is discussed, but the absorption energy with respect to ultraviolet rays having a wavelength shorter than the wavelength is not discussed.

When a polarizer protective film is disposed on at least one surface of the polarizer to form a polarizer, the polarizer may be viewed in yellow.

An object of the present invention is to provide a polarizer having excellent ultraviolet absorption energy, and when the polarizer is configured on at least one side of the polarizer, the polarizer is not easily viewed as a yellow protective film for polarizers. The polarizer protects the film and the polarizer of the polarizer.

In order to solve the above problems, the present invention provides the following inventions.

<1> A protective film for polarizers, comprising: an ultraviolet absorber A having a maximum absorption at a wavelength of 200 to 300 nm; and a wavelength of 320 ~ 400nm Ultraviolet Absorber B and Polarizer Protective Film of Thermoplastic Resin, which are characterized by a light transmittance of 3% or less at a wavelength of 260nm and a light transmittance of 5% at a wavelength of 380nm Below, and the value of b * is 0.50 or less.

<2> The polarizer protective film according to the aforementioned <1>, wherein the total amount of the ultraviolet absorbers A and B is 5 parts by weight or less based on 100 parts by weight of the thermoplastic resin.

<3> The polarizer protective film according to the aforementioned <1> or <2>, wherein the weight average molecular weights of the ultraviolet absorbers A and B are 500 to 1,000, respectively.

<4> The polarizer protective film according to any one of <1> to <3>, wherein the ultraviolet absorber A is selected from the group consisting of a triazine ultraviolet absorber, and a benzotriazole ultraviolet absorber. One or more of a group consisting of an agent, a Benzoate-based ultraviolet absorber, a Benzophenone-based ultraviolet absorber, and a Cyanoacrylate-based ultraviolet absorber.

<5> The polarizer protective film according to any one of <1> to <4>, wherein the ultraviolet absorber B is selected from the group consisting of a triazine ultraviolet absorber, a benzotriazole ultraviolet absorber, and a benzate ester One or more of a group consisting of an ultraviolet absorber, a diphenylketone-based ultraviolet absorber, and a cyanoacrylate-based ultraviolet absorber.

<6> The polarizer protective film according to any one of <1> to <5>, wherein the thermoplastic resin is selected from the group consisting of acrylic resin and polycarbonate Resin, polyester resin, norbornene resin, cellulose ester resin, cyclic olefin resin, styrene resin, methyl methacrylate-styrene resin, acrylonitrile-styrene resin One or more of a group consisting of a resin and an acrylonitrile-butadiene-styrene resin.

<7> A polarizing plate comprising a polarizer protective film according to any one of <1> to <6> described above on at least one side of the polarizer.

<8> The polarizing plate as described in <7> above, in which the polarizer protective film and the polarizer are bonded together via an adhesive layer.

<9> The polarizing plate according to the aforementioned <8>, wherein the adhesive layer is formed of an active energy ray-curable adhesive.

<10> The polarizing plate according to any one of the aforementioned <7> to <9>, wherein the polarizer is formed by adsorbing and aligning a dichroic dye to a polyvinyl alcohol resin film.

According to the present invention, it is possible to provide a polarizer protective film which has excellent ultraviolet absorption energy and is disposed on at least one side of a polarizer to constitute a polarizer, and the polarizer is not easily viewed as yellow. In addition, according to the present invention, it is possible to provide a polarizing plate that cannot be easily viewed as yellow.

The polarizer protective film of the present invention comprises: an ultraviolet absorbent A having a maximum absorption at a wavelength of 200 to 300 nm, an ultraviolet absorbent B having a maximum absorption at a wavelength of 320 to 400 nm, and a thermoplastic tree. Grease has a light transmittance of 3% or less at a wavelength of 260 nm, a light transmittance of 5% or less at a wavelength of 380 nm, and a value of b * of 0.50 or less. According to the polarizer protective film of the present invention, in addition to the absorption energy with respect to ultraviolet rays having a wavelength of 380 nm, the absorption energy with ultraviolet rays having a wavelength of 260 nm is also superior to ultraviolet rays having a shorter wavelength than the ultraviolet rays having a wavelength of 380 nm. When the polarizing plate is disposed on at least one surface of the polarizer, the polarizing plate is difficult to be viewed in yellow.

(Thermoplastic resin)

As the thermoplastic resin, various conventionally known thermoplastic resins can be used, and examples thereof include acrylic resins, cyclic olefin resins, styrene resins, methyl methacrylate-styrene resins, and acrylonitrile-styrene resins. (AS resin), acrylonitrile-styrene-butadiene resin (ABS resin), cellulose ester resin, polyester resin, polycarbonate resin, polyarylate resin, polyfluorene (also Polyether 碸) resin, polyethylene resin, polypropylene resin, cellulose diacetate resin, cellulose triacetate resin, cellulose acetate propionate resin, cellulose acetate butyrate resin, polyisocyanate Dichloroethylene resin, polyvinyl alcohol resin, ethylene-vinyl alcohol resin, para-polystyrene resin, norbornene resin, polymethylpentene resin, polyether ketone resin, polyether ketone imine Resin, polyamide resin, fluororesin and nylon resin. Of these, acrylic resins, polycarbonate resins, polyester resins, norbornene resins, cellulose ester resins, methyl methacrylate-styrene resins, AS resins, and ABS resins are preferred. Especially preferred are acrylic resins, polycarbonate resins and polyester resins. The resin is particularly preferably an acrylic resin in terms of excellent transparency or weather resistance. These thermoplastic resins may be used alone or in combination of two or more.

Examples of the acrylic resin include homopolymers of acrylic monomers such as (meth) acrylic acid, (meth) acrylates, and (meth) acrylonitrile, or two or more copolymers, acrylic monomers, and Copolymers of other monomers. In this specification, the term "(meth) acrylic acid" means "acrylic acid" and / or "methacrylic acid". Commercially available acrylic resins can be used, and examples thereof include "Sumipex EX" and "Sumipex MH" manufactured by Sumitomo Chemical Co., Ltd.

The acrylic resin is preferably a methacrylic resin from the viewpoints of excellent hardness, weather resistance, transparency, and the like. The methacrylic resin is a polymer obtained by polymerizing a methacrylate-based monomer, and examples thereof include a homopolymer of methacrylate (polyalkylmethacrylate), and 50% by weight or more. A copolymer of a methacrylate and a monomer other than 50% by weight of a methacrylate or the like. When it is a copolymer, it is preferably 70% by weight or more of methacrylate and 30% by weight or less of monomers other than methacrylate, and more preferably 90% by weight of methacrylate. It is 10% by weight or less for monomers other than methacrylate.

Examples of methacrylates include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, and methyl methacrylate. Hexyl acrylate, heptyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, n-nonyl methacrylate, isononyl methacrylate, Decyl methacrylate, undecyl methacrylate, n-pentyl methacrylate, isoamyl methacrylate, lauryl methacrylate, methoxyethyl methacrylate, ethoxyethyl methacrylate, etc. . Among them, a methacrylate having an alkyl group having 1 to 8 carbon atoms is preferred, and methyl methacrylate is particularly preferred. The methacrylate may be used alone or in combination of two or more.

Examples of monomers other than methacrylate include acrylate, unsaturated nitrile, ethylenically unsaturated carboxylic acid hydroxyalkyl ester, ethylenically unsaturated carboxylic acid amidine, ethylenically unsaturated acid, and ethylenically unsaturated sulfonic acid. Acid esters, ethylenically unsaturated alcohols and esters thereof, ethylenically unsaturated ethers, ethylenically unsaturated amines, ethylenically unsaturated silane compounds, aliphatic conjugated diene, styrene-based monomers, and the like. Among them, acrylate is preferred. The monomers other than methacrylate can be used individually by 1 type or in combination of 2 or more types.

Examples of the acrylate include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, hexyl acrylate, heptyl acrylate, and 2-ethylhexyl acrylate. , N-octyl acrylate, n-nonyl acrylate, isononyl acrylate, decyl acrylate, undecyl acrylate, n-pentyl acrylate, isoamyl acrylate, lauryl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate Esters, etc. Among them, acrylates having an alkyl group having 1 to 8 carbon atoms are preferred, and methyl acrylate is particularly preferred.

Examples of the unsaturated nitrile include acrylonitrile, α-chloroacrylonitrile, α-methoxyacrylonitrile, methacrylonitrile, and vinylidene chloride.

Examples of the ethylenically unsaturated hydroxyalkyl carboxylic acid include hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and methylpropyl Hydroxypropyl enoate, hydroxybutyl acrylate, hydroxybutyl methacrylate, and the like.

Examples of ethylenically unsaturated carboxylic acid amidines include acrylamide, methacrylamide, N-butoxymethacrylamide, N-butoxymethacrylamide, and N-butoxyethyl Methacrylamide, N-butoxyethylmethacrylamide, N-methoxymethacrylamide, N-methoxymethylmethacrylamide, N-n-propoxymethacrylamide, N-n-propoxymethylmethacrylamide, N-methacrylamide, N-methacrylamide, N, N-dimethylacrylamide, N, N-dimethylformamide Acrylamide, N, N-diethylacrylamide, N, N-diethylmethacrylamide.

Examples of ethylenically unsaturated acids include acrylic acid, methacrylic acid, itaconic acid, fumaric acid, fumaric anhydride, maleic acid, maleic anhydride, vinylsulfonic acid, Ethylene unsaturated carboxylic acids such as pentadiene sulfonic acid, ethylenically unsaturated sulfonic acids, and the like. The ethylenically unsaturated acid monomer can be neutralized with an alkali metal such as sodium or potassium, ammonia, or the like.

Examples of the ethylenically unsaturated sulfonic acid ester include alkyl vinyl sulfonate and alkyl isoprene sulfonate.

Examples of ethylenically unsaturated alcohols and their esters include allyl alcohol, methallyl alcohol, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl stearate, vinyl benzoate, and vinyl acetate. Propyl ester, allyl hexanoate, allyl laurate, allyl benzoate, vinyl alkyl sulfonate, allyl alkyl sulfonate, vinyl aryl sulfonate, and the like.

Examples of ethylenically unsaturated ethers include methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, methallyl ether, and ethyl allyl ether. .

Examples of ethylenically unsaturated amines include vinyldimethylamine, vinyldiethylamine, vinyldiphenylamine, allyldimethylamine, and methallyldiethylamine.

Examples of the ethylenically unsaturated silane compound include vinyltriethylsilane, methylvinyldichlorosilane, dimethylallylchlorosilane, vinyltrichlorosilane, and the like.

Examples of the aliphatic conjugated diene include 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2- Neopentyl-1,3-butadiene, 2-chloro-1,3-butadiene, 1,2-dichloro-1,3-butadiene, 2,3-dichloro-1,3- Butadiene, 2-bromo-1,3-butadiene, 2-cyano-1,3-butadiene, substituted linear conjugated pentadiene, linear and side chain conjugated hexadiene, etc. .

Examples of the styrene-based monomer include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, ethylstyrene, dimethylstyrene, and p-tert-butylstyrene. , 2,4-dimethylstyrene, methoxystyrene, chlorostyrene, bromostyrene, fluorostyrene, nitrostyrene, chloromethylstyrene, vinyltoluene, ethoxylated styrene , P-dimethylamine methylstyrene, etc.

In addition, a monomer other than methacrylate may be a polyfunctional monomer. Examples of the polyfunctional monomer include polyunsaturated carboxylic acid esters of polyhydric alcohols such as ethylene glycol dimethacrylate, butylene glycol dimethacrylate, and trimethylolpropane triacrylate; Allyl esters of unsaturated carboxylic acids like allyl methacrylate, allyl methacrylate, allyl cinnamate; diallyl phthalate, diallyl maleate, triene cyanurate Polyproton, polyallyl ester of triallyl isocyanate; polyethylene Benzene-like aromatic polyalkenyl compounds and the like.

Among these acrylic resins, particularly preferred are homopolymers of methyl methacrylate (polymethyl methacrylate), or 50% by weight or more and 99.9% by weight or less of methyl methacrylate and 0.1% by weight or more of 50%. Copolymers of (meth) acrylates other than methyl methacrylate in an amount of not more than% by weight. The copolymer of methyl methacrylate other than 50% by weight and 99.9% by weight and (meth) acrylates other than 0.1% by weight and 50% by weight of methyl methacrylate refers to a copolymer of methyl methacrylate and methyl methacrylate. The total amount of the ester and the (meth) acrylate is 100% by weight, and methyl methacrylate is contained at a ratio of 50% by weight to 99.9% by weight, and (meth) acrylic acid is contained at a ratio of 0.1% by weight to 50% by weight. A copolymer obtained by polymerizing an ester monomer mixture. The monomer mixture preferably contains methyl methacrylate at a ratio of 70% by weight or more and 99.9% by weight or less, and particularly preferably contains 90% by weight or more and 99.9% by weight or less.

The acrylic resin can be obtained by subjecting the monomer to a polymerization method such as an emulsion polymerization method, a suspension polymerization method, a bulk polymerization method, a casting polymerization method (casting polymerization method), or the like. The polymerization can be performed using light irradiation or a polymerization initiator, and an azo-based initiator (for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis (2,4- Dimethylvaleronitrile), etc.), peroxide-based initiators (lauric acid peroxide, benzamidine peroxide, etc.), redox-based initiators combining organic peroxides and amines, etc. Agent. The polymerization initiator is usually used in a ratio of 0.01 part by weight or more and 1 part by weight or less, preferably 0.01 part by weight or more and 0.5 part by weight or less based on 100 parts by weight of the monomer constituting the acrylic resin. Furthermore, it can be added for Amount-controlling chain transfer agents (methyl mercaptan, n-butyl mercaptan, tertiary butyl mercaptan-like linear or branched alkyl mercaptan compounds, etc.), cross-linking agents, etc.

The thermoplastic resin may contain additives such as one or two or more kinds of light diffusing agents, matting agents, dyes, light stabilizers, antioxidants, release agents, flame retardants, antistatic agents, etc., as necessary. When an additive is contained, the content is preferably 0.005% by weight or more and 30% by weight or less with respect to the total amount of the thermoplastic resin.

Rubber particles may be added to the thermoplastic resin, and particularly when an acrylic resin is used as the thermoplastic resin, rubber particles are preferably added. Here, as the rubber particles, for example, acrylic rubber particles, butadiene rubber particles, styrene-butadiene rubber particles, and the like can be used. Among them, acrylic acid is preferably used from the viewpoint of weather resistance and durability. Department of rubber particles. The rubber particles are used singly or in combination of two or more kinds having different compositions or average particle diameters.

Acrylic rubber particles are particles containing an elastic polymer mainly composed of acrylate as a rubber component, and may be particles having a single-layer structure composed only of the elastic polymer, or a layer having the elastic polymer, for example From the viewpoint of the surface hardness of the polarizer protective film, particles having a multilayer structure of a polymer layer mainly composed of methacrylate are preferably particles having a multilayer structure. The elastic polymer may be a homopolymer of acrylate or a copolymer of 50% by weight or more of acrylate and 50% by weight or less of monomers other than acrylate. Here, as the acrylate, a general alkyl acrylate can be used.

A preferable monomer composition of an elastic polymer mainly composed of acrylate, based on all monomers, contains 50% by weight or more of alkyl acrylate, 99.9% by weight or less, 0% by weight or more of 49.9% by weight of alkyl methacrylate, Monofunctional monomers other than these are 0% by weight or more and 49.9% by weight or less, and polyfunctional monomers are 0.1% by weight or more and 10% by weight or less.

Here, the alkyl acrylate in the above-mentioned elastic polymer includes, for example, the same examples as those of the acrylic ester as the monomer component of the methacrylic resin listed previously, and the carbon number of the alkyl group is usually 1 to 8, preferably It is 4 ~ 8. In addition, the alkyl methacrylate in the above-mentioned elastic polymer includes, for example, the same methacrylic acid ester as the monomer component of the methacrylic resin listed previously, and the carbon number of the alkyl group is usually 1 to 8 , Preferably from 1 to 4.

Monofunctional monomers other than the alkyl acrylate and the alkyl methacrylate in the elastic polymer are, for example, monofunctional monomers other than the alkyl methacrylate and the alkyl acrylate which are listed as monomer components of the methacrylic resin. Examples are the same. Among them, a styrene-based monomer can be preferably used.

The polyfunctional monomer in the above-mentioned elastic polymer is, for example, the same as the example of the polyfunctional monomer listed as the monomer component of the methacrylic resin, and among them, an alkenyl ester of an unsaturated carboxylic acid or a polyprotic acid may be preferably used Polyene ester.

In the above-mentioned elastic polymer, two or more of these alkyl acrylates, alkyl methacrylates, and other monofunctional monomers and polyfunctional monomers may be used as necessary.

When a multilayer structure is used as the acrylic rubber particles, the preferred example may be a layer having a polymer mainly composed of methacrylate on the outside of the layer of the elastic polymer mainly composed of acrylate, or That is, a structure having at least two layers of the above-mentioned elastic polymer mainly composed of acrylate as an inner layer and the polymer mainly composed of methacrylate as an outer layer. Here, the methacrylate of the monomer component of the polymer of the outer layer is usually an alkyl methacrylate. The polymer in the outer layer is usually formed at a ratio of 10 parts by weight to 400 parts by weight, and preferably 20 parts by weight to 200 parts by weight, with respect to 100 parts by weight of the elastic polymer in the inner layer. By constituting the polymer of the outer layer to 10 parts by weight or more with respect to 100 parts by weight of the elastic polymer of the inner layer, it is possible to make the elastic polymer less likely to agglomerate.

The preferable monomer composition of the above-mentioned outer layer polymer is based on all monomers, and contains 50% by weight or more and 100% by weight or less of alkyl methacrylate, 0% by weight or more and 50% by weight or less of alkyl acrylate, and others The monofunctional monomer is from 0% by weight to 50% by weight, and the polyfunctional monomer is from 0% by weight to 10% by weight.

The methacrylic acid alkyl ester in the polymer of the outer layer includes, for example, the same examples as the methacrylic acid esters listed previously as the monomer component of the methacrylic resin. The carbon number of the alkyl group is usually 1 to 8, It is preferably 1 to 4. Among them, methyl methacrylate can be preferably used.

The alkyl acrylate in the polymer of the outer layer is the same as the example of the acrylic ester which is listed as the monomer component of the methacrylic resin. The carbon number of the alkyl group is usually 1 to 8, preferably 1 ~ 4.

Examples of the monomers other than the alkyl methacrylate and the alkyl acrylate in the polymer of the outer layer include examples of monofunctional monomers other than methacrylate and acrylate, which are the monomer components of the methacrylic resin. The same, and the polyfunctional monomer is, for example, the same as the example of the polyfunctional monomer listed as the monomer component of the methacrylic resin.

In the polymer of the outer layer, the alkyl methacrylate, alkyl acrylate, monomers other than these, and polyfunctional monomers may be used respectively as necessary.

In addition, as a preferable example of the acrylic rubber particles having a multi-layer structure, the inner side of the above-mentioned layer of the elastic polymer mainly composed of acrylate derived from the inner layer of the above-mentioned two-layer structure can also be cited. The main polymer layer, that is, the methacrylate-based polymer is used as the inner layer, the acrylate-based elastic polymer is used as the intermediate layer, and the previous methacrylate is used as The polymer of the main body has at least three layers as the outer layer. Here, the methacrylate of the monomer component of the polymer of the inner layer is usually an alkyl methacrylate. The polymer in the inner layer is usually formed at a ratio of 10 parts by weight to 400 parts by weight, and preferably 20 parts by weight to 200 parts by weight, with respect to 100 parts by weight of the elastic polymer in the intermediate layer.

The preferable monomer composition of the above-mentioned inner layer polymer is based on all monomers, and contains 70% by weight or more and 100% by weight or less of alkyl methacrylate, 0% by weight or more and 30% by weight or less of alkyl acrylate, and others 0% by weight to 30% by weight of the monomers, and 0% by weight of the polyfunctional monomer The amount is at least 10% by weight.

The alkyl methacrylate in the polymer of the above-mentioned inner layer is the same as the example of the methacrylic acid ester as the monomer component of the methacrylic resin listed previously, and the carbon number of the alkyl group is usually 1 to 8 , Preferably from 1 to 4. Among them, methyl methacrylate can be preferably used. In addition, the alkyl acrylate in the polymer of the above-mentioned inner layer is the same as that included in the example of the acrylic ester as the monomer component of the methacrylic resin, and the carbon number of the alkyl group is usually 1 to 8, It is preferably 1 ~ 4.

Monomers other than the alkyl methacrylate and the alkyl acrylate in the polymer of the inner layer are the same as those of the monofunctional monomers other than the methacrylic acid ester and the acrylate which are the monomer components of the methacrylic resin listed above The examples are the same, and the polyfunctional monomer is, for example, the same as the example of the polyfunctional monomer listed previously as the monomer component of the methacrylic resin.

In the polymer of the said inner layer, the alkyl methacrylate, alkyl acrylate, monomers other than these, and a polyfunctional monomer can respectively use these 2 or more types as needed.

The acrylic rubber particles can be prepared by polymerizing a monomer component of an elastic polymer mainly composed of acrylate as described above by an emulsion polymerization method or the like in at least one reaction. At this time, as described above, when a layer of a polymer mainly composed of methacrylate is formed on the outer side of the layer of the elastic polymer, an emulsion polymerization method can be used in the presence of the elastic polymer. The monomer component of the polymer in the outer layer is polymerized with at least one-stage reaction to graft onto the elastic polymer.

In addition, as described previously, When forming a polymer layer mainly composed of methacrylate in one step, firstly, the monomer component of the polymer in the inner layer is polymerized by at least one step reaction by an emulsion polymerization method, etc. In the presence, the monomer component of the above-mentioned elastic polymer is polymerized by an emulsion polymerization method or the like in at least one stage to graft the polymer to the inner layer, and then in the presence of the obtained elastic polymer, the In the emulsion polymerization method and the like, a monomer component of the polymer in the outer layer is polymerized by a reaction of at least one stage to be grafted onto the elastic polymer. When the polymerization of each layer is performed in two stages, the monomer composition in each stage is not required to be formed, but the entire monomer composition may be within a predetermined range.

Regarding the particle diameter of the acrylic rubber particles, the average particle diameter of the acrylic polymer-based elastic polymer layer in the rubber particles is preferably 0.01 μm or more and 0.4 μm or less, and particularly preferably 0.05 μm or more and 0.3 μm or less. It is more preferably 0.07 μm or more and 0.25 μm or less. When the average particle diameter of the layer of the elastic polymer is larger than 0.4 μm, the transparency of the polarizer protective film may be reduced. In addition, when the average particle diameter of the layer of the elastic polymer is less than 0.01 μm, the surface hardness of the polarizer protective film may decrease.

The average particle diameter can be obtained by mixing acrylic rubber particles and methacrylic resin to form a thin film, and dyeing the elastic polymer layer with ruthenium oxide on the cross section, observing with an electron microscope, and Find the diameter of the part.

That is, when the acrylic rubber particles are mixed with a methacrylic resin and the cross section is dyed with ruthenium oxide, the methacrylic resin in the mother phase is not dyed. When present on the outside of the elastic polymer layer, the polymer of the outer layer will not be stained. Since only the layer of the above-mentioned elastic polymer is dyed, the particle diameter can be obtained from the diameter of a portion almost observed as a circular shape by an electron microscope through dyeing. When a layer of a polymer mainly composed of methacrylate exists on the inner side of the above-mentioned elastic polymer, the polymer of the inner layer is not dyed, and the outer layer of the above-mentioned elastic polymer is observed. The state of the two-layer structure of dyeing, but only the outer side of the two-layer structure, that is, the outer diameter of the above-mentioned elastic polymer layer, can be considered at this time.

When the content ratio of the rubber particles to the thermoplastic resin is 100% by weight based on the total amount of the thermoplastic resin and the rubber particles, it is preferably 40% by weight or less, and particularly preferably 30% by weight or less. When the content ratio of the rubber particles is greater than 40% by weight of the entire acrylic resin, the surface hardness of the polarizer protective film may decrease.

(Ultraviolet absorbents A and B)

The ultraviolet absorber A may be any ultraviolet absorber having a maximum absorption at a wavelength of 200 to 300 nm, and various conventionally known ultraviolet absorbers can be used, and examples thereof include triazine ultraviolet absorbers and diphenylketone ultraviolet. Absorbents, benzotriazole-based ultraviolet absorbers, benzyl ester-based ultraviolet absorbers, and cyanoacrylate-based ultraviolet absorbers. These ultraviolet absorbers can be used individually by 1 type or in combination of 2 or more types.

The ultraviolet absorber B may be any ultraviolet absorber having a maximum absorption at a wavelength of 320 to 400 nm, and various conventionally known ultraviolet absorbers can be used, and examples thereof include triazine ultraviolet absorbers and diphenylketone ultraviolet. Absorbent, benzotriazole UV absorber, benzyl acid Ester-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, and the like. These ultraviolet absorbers can be used individually by 1 type or in combination of 2 or more types.

Examples of the triazine-based ultraviolet absorber 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, 2,4-diphenyl-6- (2-hydroxy-4-hexyloxyphenyl) -1,3,5-triazine, 2 1,4-diphenyl-6- (2-hydroxy-4-octyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-decyloxy Phenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-benzyloxyphenyl) -1,3,5-triazine, and the like.

Examples of the diphenyl ketone UV absorber include 2,4-dihydroxy-diphenyl ketone, 2-hydroxy-4-methoxy-diphenyl ketone, and 2-hydroxy-4-n-octyloxy -Diphenyl ketone, 2-hydroxy-4-decyloxy-diphenyl ketone, 2-hydroxy-4-octadecyloxy-diphenyl ketone, 2,2'-dihydroxy-4-methoxy -Diphenyl ketone, 2,2'-dihydroxy-4,4'-dimethoxy-diphenyl ketone, 2,2 ', 4,4'-tetrahydroxy-diphenyl ketone and the like.

Examples of the benzotriazole-based ultraviolet absorber include 2- (2'-hydroxy-5-methylphenyl) benzotriazole and 2- (2'-hydroxy-3 ', 5'-di-tri Butyl phenyl) benzotriazole, 2- (2'-hydroxy-3'-tertiary butyl-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-5 ' -Methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-3'- Tert-butyl-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 '-(3 ", 4", 5 ", 6" -tetrahydrophthalate Fluorenimine methyl) -5'-methylphenyl) benzotriazole, 2,2-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H -Benzotriazol-2-yl) phenol), 2- (2'-hydroxy-3'-tertiary butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2 (2 ' -Hydroxy-3 ', 5'-di-tertiary-butylphenyl) -5-chlorobenzotriazole, 2 (2'-hydroxy-3', 5'-di-tertiarypentylphenyl)- 5-chlorobenzotriazole, 2 (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) -5-chlorobenzotriazole, 2 (2'-hydroxy-3', 5 '-Di-tertiary pentylphenyl) -5-chlorobenzotriazole and the like.

Benzoate-based ultraviolet absorbers include, for example, 2,4-di-tertiary-butylphenyl-3 ', 5'-di-tertiary-butyl-4'-hydroxybenzoate, 2,6- Di-tertiary-butylphenyl-3 ', 5'-di-tertiary-butyl-4'-hydroxybenzyl ester, n-hexadecyl-3,5-di-tertiary-butyl-4-hydroxybenzyl Acid esters and n-octadecyl-3,5-di-tert-butyl-4-hydroxybenzoate and the like.

Examples of the cyanoacrylate-based ultraviolet absorber include 2'-ethylhexyl-2-cyano-3,3-diphenylacrylate and ethyl-2-cyano-3- (3 ', 4' -Methylenedioxyphenyl) -acrylate and the like.

Commercially available UV absorbers A and B can be used, for example, triazine UV absorbers include "Kemisorb 102" manufactured by Chemipro Kasei Co., Ltd., and "Adekastab LAF70" manufactured by ADEKA Co., Ltd. Examples of the triazole-based ultraviolet absorber include "Adekastab LA31" manufactured by ADEKA Corporation.

The combination of the ultraviolet absorbers A and B may be a combination of an ultraviolet absorber having a maximum absorption at a wavelength of 200 to 300 nm and a combination of an ultraviolet absorber having a maximum absorption at a wavelength of 320 to 400 nm. It is not particularly limited, and may be a combination of ultraviolet absorbers of the same type and having extremely high absorption wavelengths in respective predetermined ranges, or a combination of ultraviolet absorbers of different types and having extremely high absorption wavelengths in respective predetermined ranges. For example, in the former case, the ultraviolet absorber A may be a triazine-based ultraviolet absorber having a maximum absorption at a wavelength of 200 to 300 nm, and the ultraviolet absorbent B may be a triazine-based ultraviolet absorber having a maximum absorption at a wavelength of 320 to 400 nm. Combination and so on. In the latter case, the ultraviolet absorber A is a triazine-based ultraviolet absorber having a maximum absorption at a wavelength of 200 to 300 nm, and the ultraviolet absorbent B is a benzotriazole-based ultraviolet absorber having a maximum absorption at a wavelength of 320 to 400 nm. Combination and so on.

In addition, the ultraviolet absorbers A and B may be one type or two or more types, respectively. Ultraviolet absorbers are those who have particularly excellent ultraviolet absorption energy, but the polarizing plate is easy to be seen as yellow, or those who do not have particularly excellent ultraviolet absorption energy, but the polarizing plate is not easy to be seen as yellow. Moreover, the polarizing plate is not easily viewed as a yellow polarizer protective film, and it is preferable to appropriately combine these ultraviolet absorbers with different properties. For example, only one type of ultraviolet absorbent A is used, but ultraviolet absorbent B is particularly excellent in ultraviolet absorption energy, but the polarizing plate is easy to be viewed as yellow, and the polarizing plate is not easy to be viewed without being particularly excellent in ultraviolet absorption energy. The yellow ones. In this way, a person who has particularly excellent ultraviolet absorption energy but the polarizer is easy to be seen as yellow, and a person who does not have particularly excellent ultraviolet absorption energy but the polarizer is not easy to be seen as yellow are used in combination. When a polarizing plate is formed on at least one surface of the polarizer, the polarizing plate is difficult to be viewed as yellow. Seen better. In this example, a case where two types of ultraviolet absorbers B are used in combination is shown, but a case where two types of ultraviolet absorbers A are used in combination is also preferable from the same viewpoint.

The weight average molecular weights of the ultraviolet absorbers A and B are preferably 500 to 1,000, particularly preferably 550 to 700. When the weight average molecular weights of the ultraviolet absorbers A and B are too small, smoke tends to be generated during the molding of the polarizer protective film, and when the weight average molecular weight is too large, the compatibility with the thermoplastic resin tends to decrease.

The molar absorption coefficients of the ultraviolet absorbers A and B at the wavelengths of maximum absorption are preferably 10 L / mol ‧ cm or more, and particularly preferably 15 L / mol ‧ cm or more. By setting the Molar absorption coefficients of the ultraviolet absorbers A and B in the wavelengths of maximum absorption to the above-mentioned predetermined ranges, respectively, the ultraviolet absorption energy of the polarizer protective film can be more excellent, and the ultraviolet absorber can also be reduced Content in polarizer protective film.

(Polarizer protective film)

The polarizer protective film contains the above-mentioned ultraviolet absorber A, ultraviolet absorber B, and a thermoplastic resin, and may further contain other components as necessary. The polarizer protective film has excellent ultraviolet absorption energy by containing ultraviolet absorbents A and B. Other components include, for example, rubber particles, antioxidants, lubricants, organic dyes, inorganic dyes, pigments, antistatic agents, and surfactants.

Polarizer protective film with a light transmittance of 3% or less at a wavelength of 260nm and a light transmittance of 5% or less at a wavelength of 380nm under. The polarizer protective film has a light transmittance at a wavelength of 260 nm and a wavelength of 380 nm of 3% or less and 5% or less, respectively, and can have excellent ultraviolet absorption energy. The light transmittance at a wavelength of 260 nm is preferably 2% or less, and the light transmittance at a wavelength of 380 nm is preferably 4% or less. In order to set the light transmittance in the wavelengths of 260nm and 380nm to within a predetermined range, for example, for the light transmittance in the wavelength of 260nm, an ultraviolet absorber with a larger Mohr absorption coefficient in the wavelength with a great absorption can be used as As the ultraviolet absorber A, for the light transmittance at a wavelength of 380 nm, an ultraviolet absorbent having a larger Mohr absorption coefficient at a wavelength with a large absorption can be used as the ultraviolet absorbent B.

The polarizer protective film has a b * value of 0.50 or less. The polarizer protective film has a value of b * of 0.50 or less. When the polarizer is configured on at least one side of the polarizer to form a polarizer, the polarizer is not easily viewed as yellow. b * is the coordinate of the L * a * b * color system indicating the attributes of color perception composed of hue and chroma. When the value exceeds 0.50, the polarizer protective film is arranged on at least one side of the polarizer. The resulting polarizer will be viewed in yellow. The value of b * is preferably -0.50 or more. When the value of b * is less than -0.50, a polarizing plate obtained by disposing a polarizer protective film on at least one side of the polarizer may be viewed in blue. From the viewpoint of making the polarizing plate difficult to be viewed as yellow and difficult to be viewed as blue, it is preferable to set the value of b * to a range of -0.50 or more and 0.50 or less. In order to set the value of b * to a predetermined range, for example, an ultraviolet absorber having absorption in the visible wavelength region can be used as the ultraviolet absorber A and / or B in a manner to correct hue.

Content of UV absorber in polarizer protective film, From the viewpoint of suppressing smoke generation during the formation of the polarizer protective film, it is preferably 5 parts by weight or less, and particularly preferably 3 parts by weight or less, based on 100 parts by weight of the thermoplastic resin.

The thickness of the polarizer protective film is preferably 10 to 500 μm, particularly preferably 10 to 300 μm, more preferably 10 to 100 μm, and particularly preferably 10 to 40 μm. When it is too thin, it is difficult to maintain the shape of the polarizer protective film with respect to the shrinkage of the polarizer, and when it is too thick, it becomes heavy and difficult to handle.

The polarizer protective film is not particularly limited as long as it includes the ultraviolet absorber A, the ultraviolet absorber B, and the thermoplastic resin, and the values of the light transmittance and b * at a specific wavelength are in a predetermined range, respectively. , Can be a single-layer structure or a multilayer structure. Among them, a multilayer structure is preferred.

When the polarizer protective film has a multilayer structure, the ultraviolet absorber A, the ultraviolet absorber B, and the thermoplastic resin may all be contained in one layer, or the ultraviolet absorber A and the ultraviolet absorber B may be contained in different layers. The multilayer structure includes, for example, a layer including at least one of the layer (I) containing the ultraviolet absorbent A, the ultraviolet absorbent B, and the thermoplastic resin, and the layers including the thermoplastic resin and the ultraviolet absorbers A and B are not laminated. Structure of layer (II); structure of layer (II) containing ultraviolet absorbent B and thermoplastic resin laminated on at least one side of layer (I) containing ultraviolet absorbent A and thermoplastic resin; At least one surface of the ultraviolet absorbent A, the ultraviolet absorbent B, and the thermoplastic resin layer (I) is laminated with one of the ultraviolet absorbent A and the ultraviolet absorbent B and the thermoplastic resin layer (II). Composition; and containing ultraviolet light The structure of layer (II) including ultraviolet absorber A, ultraviolet absorber B, and thermoplastic resin is laminated on at least one surface of absorbent A, ultraviolet absorber B, and layer (I) of the thermoplastic resin. In each layer configuration, when the ultraviolet absorber A, the ultraviolet absorber B, or the thermoplastic resin is contained in the layers (I) and (II), the ultraviolet absorber A and ultraviolet contained in the layers (I) and (II) The kinds or contents of the absorbent B or the thermoplastic resin may be the same or different. In addition, the multilayer structure may be formed by laminating other layers in addition to the layer (I) and the layer (II).

The polarizer protective film may be subjected to a surface treatment, and the surface treatment may be, for example, a hard coat film treatment, an anti-glare treatment, or an anti-fouling treatment.

The method for obtaining the polarizer protective film is not particularly limited, and examples thereof include first obtaining a resin composition containing ultraviolet absorber A, ultraviolet absorber B, and a thermoplastic resin, followed by melt extrusion molding method and solution casting film forming method. A method of molding the resin composition, such as hot pressing. Among them, melt extrusion molding is preferred.

In the melt extrusion molding method, for example, firstly, ultraviolet absorber A, ultraviolet absorber B, and a thermoplastic resin are mixed, and if necessary, the other components are further mixed to obtain a resin composition, and then a uniaxial or biaxial extruder is used. The obtained resin composition is melt-kneaded, and then the molten resin is continuously extruded into a film shape from the T stamper, and then the thin film-like molten resin continuously extruded from the T stamper is held on a pair of surfaces to be smooth Forming and cooling between metal rolls to obtain a polarizer protective film. The ultraviolet absorber A, the ultraviolet absorber B, the thermoplastic resin, and other components required for mixing are not particularly limited, and any one can be used. Commonly known methods can use super mixers or Banbury Mixers, melt-kneading by single-shaft or double-shaft extruders, or a combination of these methods.

When the polarizer protective film has the above-mentioned multilayer structure, for example, a plurality of uniaxial or biaxial extruders may be used to melt-knead the resin composition constituting the layer (I) and the resin composition constituting the layer (II), respectively. Then, a method such as laminating by a lamination die or a multi-manifold pressing die is used.

The polarizer protective film can be stretched by longitudinal stretching and / or transverse stretching. The polarizer protective film is stretched by longitudinal stretching and / or transverse stretching, which can have excellent mechanical strength and improve productivity or handling. In this specification, stretching in the mechanical flow direction of the unstretched film means longitudinal stretching, and stretching in a direction orthogonal to the mechanical flow direction of the unstretched film means lateral stretching.

The above stretching may be uniaxial stretching, but is preferably sequential stretching or simultaneous biaxial stretching. The stretching ratio is preferably 1.1 to 3.0 times.

The thickness of the stretched film is preferably 10 to 500 μm, particularly preferably 10 to 300 μm, more preferably 10 to 100 μm, and particularly preferably 10 to 40 μm. When the thickness is too thin, the strength and rigidity disappear, which makes handling at the time of production difficult. When the thickness is too thick, it is difficult to take up the film, which significantly deteriorates the line speed and productivity.

Polarizer protective films, in addition to the use of polarizer protection, can be laminated to the building lighting members such as windows or garage roof materials, vehicle lighting members such as windows, agricultural lighting members such as greenhouses, lighting members, It can be used as a display member such as a front panel filter, etc. In addition, it can also be laminated on the housing of a home appliance or a vehicle interior structure as a decorative film. Pieces, interior building materials, wallpaper, makeup boards, entrance doors, window frames, kick boards, etc.

(Polarizer)

The polarizer protective film can be arranged on at least one surface of the polarizer to constitute a polarizing plate. The polarizer protective film and the polarizing plate are preferably bonded together.

The polarizer may follow a generally known method, through the step of uniaxially stretching the polyvinyl alcohol resin film, the step of dyeing the polyvinyl alcohol resin film with a dichroic dye, and adsorbing the dichroic dye, A step of treating a polyvinyl alcohol-based resin film to which a dichroic dye is adsorbed with an aqueous boric acid solution, and a step of washing with a boric acid aqueous solution after the treatment are performed. The polarizer obtained in this manner has an absorption axis in the aforementioned uniaxially stretched direction.

As the polyvinyl alcohol resin, a saponified polyvinyl acetate resin can be used. Examples of the polyvinyl acetate-based resin include copolymers of vinyl acetate and other monomers copolymerizable therewith, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate. Examples of other monomers that can be copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

The saponification degree of the polyvinyl alcohol-based resin is preferably 85 to 100 mol%, particularly preferably 98 mol% or more. The polyvinyl alcohol-based resin can be modified. For example, polyvinyl aldehyde or polyvinyl acetal modified by aldehydes can be used. The polymerization degree of the polyvinyl alcohol-based resin is preferably 1,000 to 10,000, and particularly preferably 1500 to 5,000.

Those using this polyvinyl alcohol-based resin can be used as a roll blank material film of a polarizer. The method for forming a polyvinyl alcohol-based resin into a film is not particularly limited, and a generally known method can be adopted. The thickness of the polyvinyl alcohol-based roll blank material film is preferably 10 to 150 μm.

The uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before, simultaneously with, or after dyeing the dichroic pigment. When uniaxial stretching is performed after dyeing, the uniaxial stretching may be performed before or during a boric acid treatment. In addition, uniaxial stretching may be performed in these plural stages.

Uniaxial stretching can be performed by passing between rollers with different peripheral speeds and separated from each other, or by holding them with a hot roller. In addition, this uniaxial stretching may be dry stretching in the air, or wet stretching using a solvent such as water or an organic solvent and swelling the polyvinyl alcohol resin film. Stretch. The stretching ratio is preferably 3 to 8 times.

The dyeing of a polyvinyl alcohol-based resin film based on a dichroic dye can be performed, for example, by immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a dichroic dye. As a dichroic pigment, iodine or a dichroic organic dye can be used. The polyvinyl alcohol-based resin film is preferably treated by being immersed in water before the dyeing treatment.

When iodine is used as a dichroic dye, a method in which a polyvinyl alcohol-based resin film is immersed in an aqueous solution containing iodine and potassium iodide for dyeing is generally adopted. The content of iodine in the aqueous solution is preferably 0.01 to 1 part by weight per 100 parts by weight of water, and the content of potassium iodide is preferably 0.5 to 20 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution used for dyeing is preferably 20 to 40 ° C. In addition, the immersion time in the aqueous solution (Dyeing time) is preferably 20 to 1800 seconds.

On the other hand, when a dichroic organic dye is used as the dichroic dye, a method in which a polyvinyl alcohol-based resin film is dipped in an aqueous solution containing a water-soluble dichroic organic dye for dyeing is generally adopted. The content of the dichroic organic dye in the aqueous solution is preferably 0.0001 to 10 parts by weight, and more preferably 0.001 to 1 part by weight per 100 parts by weight of water. The aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing aid. The temperature of the dichroic dye aqueous solution used for dyeing is preferably 20 to 80 ° C. The immersion time (dyeing time) in the aqueous solution is preferably 10 to 1800 seconds.

The boric acid treatment after the dyeing of the dichroic pigment can be performed by immersing the dyed polyvinyl alcohol-based resin film in an aqueous solution containing boric acid. The amount of boric acid in the boric acid-containing aqueous solution is preferably 2 to 15 parts by weight, and particularly preferably 5 to 12 parts by weight per 100 parts by weight of water. When iodine is used as the dichroic dye, the boric acid-containing aqueous solution preferably contains potassium iodide. The amount of potassium iodide in the boric acid-containing aqueous solution is preferably 0.1 to 15 parts by weight, and particularly preferably 5 to 12 parts by weight per 100 parts by weight of water. The immersion time in the boric acid-containing aqueous solution is preferably 60 to 1200 seconds, particularly preferably 150 to 600 seconds, and more preferably 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is preferably 50 ° C or higher, more preferably 50 to 85 ° C, and even more preferably 60 to 80 ° C.

The polyvinyl alcohol-based resin film after the boric acid treatment is usually subjected to a water washing treatment. The water washing treatment can be performed, for example, by immersing a polyvinyl alcohol-based resin film treated with boric acid in water. The temperature of the water in the water washing treatment is preferably 5 to 40 ° C. The dipping time is preferably 1 to 120 seconds.

A polarizer can be obtained after washing with water and drying. The drying process can be performed using a hot-air dryer or a far-infrared heater. The temperature of the drying treatment is preferably 30 to 100 ° C or more, and particularly preferably 50 to 80 ° C. The drying time is preferably 60 to 600 seconds, and particularly preferably 120 to 600 seconds.

By drying, the moisture content of the polarizer can be reduced to a practical level. The moisture content is preferably 5 to 20% by weight, and particularly preferably 8 to 15% by weight. When the moisture content is less than 5% by weight, the polarizer loses flexibility, and the polarizer may be damaged or broken after drying. On the other hand, when the moisture content exceeds 20% by weight, the thermal stability of the polarizer may be insufficient.

The thickness of the polarizer obtained by adsorbing and aligning the dichroic pigment thus obtained with the polyvinyl alcohol resin film is preferably 5 to 40 μm.

When the polarizer protective film is disposed on one surface of the polarizer, a transparent resin film may be disposed on the other surface of the polarizer. The transparent resin film and the polarizer are the same as those of the polarizer protective film and the polarizer, and are preferably bonded together. Examples of the transparent resin film include a cellulose triacetate film, a polycarbonate film, a polyethylene terephthalate film, an acrylic resin film, a laminated film of an acrylic resin and a polycarbonate resin, and an olefin-based film. Resin film and so on.

The olefin-based resin is, for example, a resin obtained by polymerizing a chain olefin monomer such as ethylene or propylene or a cyclic olefin monomer such as norbornene or other cyclopentadiene derivatives using a polymerization catalyst.

Examples of the olefin-based resin obtained from the chain-shaped olefin monomer include a polyethylene-based resin and a polypropylene-based resin. Among them, polypropylene resins which are homopolymers of propylene are preferred. In addition, it is mainly composed of propylene, and preferably A ratio of 1 to 20% by weight, particularly preferably a polypropylene copolymer resin that copolymerizes a comonomer copolymerizable with propylene at a ratio of 3 to 10% by weight.

The comonomer copolymerizable with propylene is preferably ethylene, 1-butene or 1-hexene. Among them, from the viewpoint of relatively excellent transparency or stretch processability, ethylene may be preferably used, and ethylene may be copolymerized at a ratio of 1 to 20% by weight, preferably at a ratio of 3 to 10% by weight. A polypropylene copolymer resin is preferred. By setting the copolymerization ratio of ethylene to 1% by weight or more, transparency or stretch processability can be improved. On the other hand, when the ratio exceeds 20% by weight, the melting point of the resin decreases, and the heat resistance required for the protective film or the retardation film may be impaired.

Commercially available polypropylene-based resins can be used. Examples include "Prime Polypro" manufactured by Prime Polymer Co., Ltd., "Novatec" and "Wintec" manufactured by Japan Polypropylene Co., Ltd., and "Sumitomo" manufactured by Sumitomo Chemical Co., Ltd. Norbrene "," Sun Allomer "by Sun Allomer Co., Ltd., etc.

The olefin-based resin obtained by polymerizing a cyclic olefin monomer is generally also referred to as a cyclic olefin-based resin, an alicyclic olefin-based resin, or a norbornene-based resin. This is called a cyclic olefin resin.

Cyclic olefin-based resins include, for example, the development of norbornene or a derivative thereof derived from cyclopentadiene and an olefin through a Diels-Alder reaction as a monomer. Resin obtained by ring-shift polymerization and subsequent hydrogenation; obtained from dicyclopentadiene, olefins or (meth) acrylates by Diels-Adel reaction Tetracyclododecene or a derivative thereof is a monomer that undergoes ring-opening shift polymerization, and is then obtained by successive hydrogenation; using two or more kinds of norbornene, tetracyclododecene, and the like Derivatives or other cyclic olefin monomers are similarly subjected to ring-opening shift copolymerization, and then resins obtained by successive hydrogenation; selected from the aforementioned norbornene, tetracyclododecene, and the like At least one kind of cyclic olefin of the derivative, and a resin obtained by addition copolymerization with an aliphatic or aromatic compound having a vinyl group.

Commercial products can be used for the cyclic olefin resin, and examples thereof include "TOPAS" manufactured by TOPAS ADVANCED POLYMERS GmbH, "Arton" manufactured by JSR Corporation, "Zeonor" and "Zeonex" manufactured by Zeon Japan Corporation. , "Apel" manufactured by Mitsui Chemicals Co., Ltd., etc.

By forming a thin film of a chain olefin resin or a cyclic olefin resin, a transparent resin film can be formed. The method for forming a thin film can be the same as the method for obtaining a polarizer protective film described above.

Commercially available olefin-based resin films can be used. For example, polypropylene resin films include "FILMAX CPP Film" manufactured by FILMAX Corporation, "Suntox" manufactured by Sun‧Tox Corporation, and Tohcello Corporation. "Tohcello" by Toyobo, "Toyobo Pylen Film" by Toyobo Corporation, "Torayfan" by Toray Advanced Film Co., Ltd., "Nihon Polyace" by Japan Polyace Co., Ltd., and Futamura Chemical Co., Ltd. "Taihe FC" and so on. Examples of cyclic olefin resin films include Zeon Japan Co., Ltd. "Zeonor Film" made by a limited company, "Arton Film" made by JSR Co., Ltd., etc.

The transparent resin film can be laminated with an optically functional film on the surface or coated with an optically functional layer. Examples of the optically functional film and optically functional layer include an easy-adhesive layer, a conductive layer, and a hard coat layer.

The olefin-based resin film can be stretched to give the film a refractive index anisotropy, thereby imparting the function of a retardation film. The stretching method can be appropriately selected according to the required refractive index anisotropy, and is not particularly limited. Examples of the stretching method include uniaxial stretching in the longitudinal direction, uniaxial stretching in the transverse direction, and successive biaxial stretching in the longitudinal and lateral directions.

Olefin resins have positive refractive index anisotropy and have the largest refractive index in the direction in which stress is applied. Therefore, uniaxially stretched films usually give refractive index anisotropy of nx> ny ≒ nz. Here, nx is the refractive index of the in-plane slow axis direction of the film (the direction with the largest refractive index in the plane, and the stretching direction in the resin with positive refractive index anisotropy), and ny is the in-plane of the film. The refractive index in the fast axis direction (the direction orthogonal to the fast axis in the plane), and nz is the refractive index in the normal direction of the film. Films of olefin resins that are successively biaxially stretched usually have refractive index anisotropy of nx> ny> nz.

In addition, in order to provide desired refractive index characteristics, a retardation film may be produced by bonding to a film for the purpose of heat shrinkable film, and replacing stretching or shrinking the film together with stretching processing. This operation is usually used to obtain a retardation film with refractive index anisotropy of nx> ny> nz or nz> nx ≧ ny.

A commercially available retardation film made of an olefin-based resin can be used. For example, a retardation film made of a cyclic olefin-based resin includes "Zeonor Film" manufactured by Zeon Japan Co., Ltd. and JSR Co., Ltd. "Arton Film" made by the company, "S-Thinner retardation film" made by Sekisui Chemical Industry Co., Ltd., etc.

The bonding of the polarizer protective film and the polarizer and the bonding of the polarizer and the transparent resin film are preferably an adhesive. By using an adhesive, a polarizer protective film and a polarizer, and a polarizer and a transparent resin film can be bonded via an adhesive layer. In addition, before the bonding, at least one of the bonding surfaces is preferably subjected to a corona discharge treatment, a plasma irradiation treatment, an electron beam irradiation treatment, or other surface activation treatment.

The adhesive used to form the adhesive layer can be arbitrarily selected and used from adhesives that exhibit an adhesive force with respect to each member. Typical examples include water-based adhesives. Even if the adhesive component is dissolved in water or the adhesive component is dispersed in water, or active energy ray-curable adhesive containing a component hardened by irradiation with active energy ray, Agent. Among them, an active energy ray-curable adhesive is preferred from the viewpoint of productivity.

As the water-based adhesive, for example, a composition using a polyvinyl alcohol resin or a urethane resin can be cited as a preferable adhesive.

When a polyvinyl alcohol-based resin is used as a main component of the water-based adhesive, for example, the polyvinyl alcohol-based resin includes, in addition to partially saponified polyvinyl alcohol or completely saponified polyvinyl alcohol, polyvinyl alcohol modified by a carboxyl group. Polyvinyl alcohol modified by acetic acid acetate, polyvinyl alcohol modified by methylol, modified polyvinyl alcohol-like tree like polyvinyl alcohol modified by amine fat. When a polyvinyl alcohol-based resin is used as an adhesive component, the adhesive is often an aqueous solution prepared as a polyvinyl alcohol-based resin. The concentration of the polyvinyl alcohol-based resin in the adhesive solution is preferably 1 to 10 parts by weight, and more preferably 1 to 5 parts by weight with respect to 100 parts by weight of water.

In the water-based adhesive containing a polyvinyl alcohol-based resin as a main component, in order to improve adhesion, it is preferable to add a hardening component such as glyoxal or a water-soluble epoxy resin or a crosslinking agent. Examples of the water-soluble epoxy resin include polyamines obtained by reacting epichlorohydrin with a polyalkylene polyamine such as diethylenetriamine or triethylenetetramine and a dicarboxylic acid such as adipic acid. Polyamine polyamine epoxy resin and the like obtained by the reaction. Commercially available polyamine epoxy resins can be used. Examples include "Sumirez Resin 650" and "Sumirez Resin 675" manufactured by Sumitomo Chemtex Co., Ltd., and "WS-525" manufactured by Japan PMC Co., Ltd. . The amount of these hardening components or cross-linking agents to be added is preferably 1 to 100 parts by weight, and more preferably 1 to 50 parts by weight based on 100 parts by weight of the polyvinyl alcohol resin. When the added amount is small, the adhesion improvement effect is reduced. On the other hand, when the added amount is large, the adhesive layer may become brittle.

When a urethane resin is used as the main component of the water-based adhesive, examples of a suitable adhesive composition include a mixture of a polyester-based ionic polymer-type urethane resin and a compound having a glycidyloxy group. The so-called polyester-based ionic polymer urethane resin is a urethane resin having a polyester skeleton, and a small amount of an ionic component (hydrophilic component) is introduced therein. Ionic polymer-type urethane resin, which can be emulsified by emulsifying directly in water without using an emulsifier Emulsion, so it can be used as a water-based adhesive.

When an active energy ray-curable adhesive is used, the components (hereinafter sometimes referred to simply as "curable components") that are hardened by irradiation with active energy rays include epoxy compounds and oxetane compounds. , Acrylic compounds, etc. When using a cationic polymerizable compound such as an epoxy compound or an oxonium compound, a cationic polymerization initiator is prepared. When a radical polymerizable compound such as an acrylic compound is used, a radical polymerization initiator is prepared. Among them, an adhesive agent using an epoxy compound as one of the hardening components is preferred, and an alicyclic epoxy compound having an epoxy group directly bonded to a saturated carbocyclic ring as a curing agent is particularly preferred. In addition, an oxo compound may be used in combination.

Commercially available epoxy compounds can be used. Examples include the "Epikote" series manufactured by Japan Epoxy Resin Co., Ltd., the "Epiclon" series manufactured by DIC Co., Ltd., the "Epotote" series manufactured by Tohto Kasei Co., Ltd., and ADEKA. The "Adeka Resin" series manufactured by Co., Ltd., the "Denacol" series manufactured by Nagase Chemitex Co., Ltd., the "Dow Epoxy" series manufactured by Dow Chemical Co., Ltd., and "Tepic" manufactured by Nissan Chemical Industry Co., Ltd.

As the alicyclic epoxy compound in which an epoxy group is directly bonded to a saturated carbocyclic ring, a commercially available product can be used, and examples thereof include "Celloxide" series and "Cyclomer" series manufactured by Daicel Chemical Industry Co., Ltd., and those manufactured by Dow Chemical Company. "Cyracure" series, etc.

Commercially available oxyfluorene compounds can be used. "Aronoxetane" series manufactured by Akasei Co., Ltd., "ETERNACOLL" series manufactured by Ube Kosan Co., Ltd., etc.

Commercially available cationic polymerization initiators can be used, and examples thereof include "Kayarad" series manufactured by Nippon Kayaku Co., Ltd., "Cyracure" series manufactured by Union Carbide Co., Ltd., and photoacid manufactured by San-Apro Co., Ltd. "CPI" series of generators, "TAZ", "BBI" and "DTS" of photoacid generators by Midori Kagaku Co., Ltd., "Adeka Optomer" series by ADEKA Co., Ltd., and "RHODORSIL" by Rhodia Co., Ltd. Series.

The active energy ray-curable adhesive may contain a photosensitizer if necessary. By using a photosensitizer, the reactivity can be improved, and the mechanical strength or adhesion strength of the hardened layer can be further improved. Examples of the photosensitizer include carbonyl compounds, organic sulfur compounds, persulfur compounds, redox compounds, azo and diazo compounds, anthracene compounds, halogen compounds, and photoreducing dyes.

In the active energy ray-curable adhesive, various additives can be blended so long as the adhesiveness is not impaired. Examples of the additives include ion trapping agents, antioxidants, chain transfer agents, adhesion-imparting agents, thermoplastic resins, fillers, flow modifiers, plasticizers, and defoamers. In addition, as long as the adhesiveness is not impaired, a hardening component that is hardened by a reaction mechanism different from that of cationic polymerization may be blended.

The activation energy ray hardening adhesives described above may be the same composition or different compositions, but the activation energy rays used to harden the two The irradiation is preferably performed simultaneously.

Examples of the active energy rays include X-rays, ultraviolet rays, and visible rays. Among these, from the viewpoints of ease of application and ease of preparation of 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 thickness of the adhesive layer obtained by using an active energy ray-curable adhesive is preferably 1 to 50 μm, and more preferably 1 to 10 μm.

The polarizing plate can be bonded to a liquid crystal cell to form a liquid crystal panel used in a liquid crystal display device. The polarizing plate and the liquid crystal cell are preferably bonded using an adhesive and interposed between the adhesive layers. The adhesive layer is generally formed of an acrylic adhesive with an acrylic ester as a main component and an acrylic resin copolymerized with an acrylic resin containing a functional group-containing acrylic monomer as an 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.

[Example]

The following series of examples illustrate the present invention in detail, but the present invention is not limited to these.

The ultraviolet absorbents used in the following examples and comparative examples are as follows.

Ultraviolet absorbent A1: Ultraviolet absorbent "Kemisorb 102" (maximum absorption: wavelength) manufactured by Chemipro Kasei Co., Ltd. 280nm, Molar absorption coefficient: 68.3L / mol‧cm, weight average molecular weight: 508.9, triazine ultraviolet absorber)

Ultraviolet absorbent A2: Ultraviolet absorber "Tinuvin 1577" manufactured by BASF Co., Ltd. (maximum absorption: wavelength 280nm, Molar absorption coefficient: 82.0L / mol‧cm, weight average molecular weight: 425, triazine-based ultraviolet absorber)

Ultraviolet absorbent B1: Ultraviolet absorbent "Adekastab LAF70" manufactured by ADEKA Co., Ltd. (maximum absorption: wavelength 356nm, molar absorption coefficient: 65.7L / mol‧cm, weight average molecular weight: 699.9, triazine-based ultraviolet absorber)

Ultraviolet absorbent B2: Ultraviolet absorbent "Adekastab LA31" manufactured by ADEKA Co., Ltd. (maximum absorption: wavelength 350nm, Molar absorption coefficient: 18.0L / mol‧cm, weight average molecular weight: 658, benzotriazole-based ultraviolet absorber Agent)

(Example 1)

First, 1.2 parts by weight of the ultraviolet absorber A1, 0.6 parts by weight of the ultraviolet absorber B1, and 0.9 parts by weight of the ultraviolet absorber B2 were mixed with 100 parts by weight of an acrylic resin "Sumipex MH" (manufactured by Sumitomo Chemical Co., Ltd.) ) To obtain a resin composition, the obtained resin composition was melt-kneaded with a uniaxial extruder with a vent diameter of 65 mm and a vented hole, and the molten resin was supplied to a T-die. Next, the supplied molten resin is continuously extruded from the T die into a film shape, and then the thin film-shaped molten resin continuously extruded from the T die is held between a pair of smooth metal surfaces. Form and cool between rolls to obtain a polarizer protective film with a thickness of 40 μm.

(Example 2)

A polarizer protective film having a thickness of 40 μm was obtained in the same manner as in Example 1 except that the ultraviolet absorber A1 was 0.9 parts by weight.

(Comparative example 1)

A polarizer protective film having a thickness of 40 μm was obtained in the same manner as in Example 1 except that the ultraviolet absorber A1 was 0.5 parts by weight and the ultraviolet absorber B1 was 0.9 parts by weight, and the ultraviolet absorber B2 was not mixed.

(Comparative example 2)

A polarizer protective film having a thickness of 40 μm was obtained in the same manner as in Comparative Example 1 except that 0.5 parts by weight of the ultraviolet absorber A2 was used instead of the ultraviolet absorber A1.

For each of the obtained polarizer protective films (Examples 1, 2 and Comparative Examples 1, 2), the values of light transmittance and b * were evaluated by the following methods, respectively.

<Evaluation of Light Transmission>

The obtained polarizer protective films were measured using a spectrophotometer U-4100 manufactured by Hitachi High-Tech Fielding Co., Ltd. Light transmittance at a length of 260 nm and light transmittance at a wavelength of 380 nm. The measurement results are shown in Table 1.

<B * Assessment>

For each of the obtained polarizer protective films, b * was measured by a loaded program using a spectrophotometer U-4100 manufactured by Hitachi High-Tech Fielding Co., Ltd. The measurement results are shown in Table 1.

For each of the obtained polarizer protective films (Examples 1, 2 and Comparative Examples 1, 2), a polarizing plate was produced by the following method, and the yellowness of the polarizing plate was evaluated by the following method.

The polarizer protective films obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were respectively placed between ultraviolet curable adhesives containing epoxy compounds as the main component, and the thickness of the polarizer protective films obtained in Examples 1 and 2 and polyvinyl alcohol was aligned to about 100%. A retardation film formed by biaxially stretching a cycloolefin-based resin film on one side of a polarizer of 30 μm with an ultraviolet curing adhesive mainly containing an epoxy compound as the main component. The other side of the polarizer is then irradiated with ultraviolet rays to harden the ultraviolet curable adhesive to obtain a polarizing plate.

<Yellowness Evaluation>

Each of the obtained polarizing plates (Examples 1 and 2 and Comparative Examples 1 and 2) was visually observed. Those who viewed yellow were evaluated as ×, and those who were not viewed yellow were evaluated as ○. The evaluation results are shown in Table 1.

Claims (7)

A polarizer protective film, comprising: an ultraviolet absorbent A having a maximum absorption at a wavelength of 200 to 300 nm; an ultraviolet absorbent B having two or more different types of an ultraviolet absorber having a maximum absorption at a wavelength of 320 to 400 nm; and a thermoplastic resin; The total amount of the ultraviolet absorbers A and B is more than 0 parts by weight and 5 parts by weight or less based on 100 parts by weight of the thermoplastic resin. The ultraviolet absorbers A and B are each independently selected from a triazine-based ultraviolet absorber, benzene, and the like. The group consisting of Benzotriazole UV absorber, Benzoate UV absorber, Benzophenone UV absorber and Cyanoacrylate UV absorber One or more types, the polarizer protective film has a thickness of 10 to 500 μm, a light transmittance of 3% or less at a wavelength of 260 nm, a light transmittance of 5% or less at a wavelength of 380 nm, and a value of b * It is 0.50 or less. For example, the polarizer protective film of claim 1, wherein the weight average molecular weights of the ultraviolet absorbers A and B are 500 to 1,000, respectively. For example, the polarizer protective film of claim 1 or 2, wherein the thermoplastic resin is selected from the group consisting of acrylic resin, polycarbonate resin, polyester resin, norbornene resin, cellulose ester resin, and cyclic resin. One or more of a group consisting of an olefin resin, a styrene resin, a methyl methacrylate-styrene resin, an acrylonitrile-styrene resin, and an acrylonitrile-butadiene-styrene resin. A polarizing plate is formed by arranging a polarizer protective film according to any one of claims 1 to 3 on at least one side of a polarizer. For example, the polarizing plate of claim 4, wherein the polarizer protective film and the polarizer are interposed and adhered together. The polarizing plate according to claim 5, wherein the adhesive layer is formed of an active energy ray-curable adhesive. For example, the polarizing plate of claim 4, wherein the polarizer is a dichroic pigment adsorbed and aligned with a polyvinyl alcohol resin film.