WO2021039123A1 - Resin composition for polarizer protection and polarizing plate comprising protective layer formed from said composition - Google Patents

Abstract

Provided are: a resin composition for polarizer protection that has excellent adhesion to a polarizer and can prevent defects such as decoloration from an edge or whitening of a protective layer; and a polarizing plate comprising a protective layer formed from said resin composition. A resin composition for polarizer protection according to the present invention comprises: a polymer (A) obtained by polymerizing more than 50 parts by weight of an acrylic monomer and more than 0 parts by weight but less than 50 parts by weight of the monomer represented by formula (1); and an epoxy resin (B). The content ratio of the polymer (A) to the epoxy resin (B) is 95:5 to 60:40 or 40:60 to 1:99 by weight. (In the formula: X represents a functional group that includes at least one reactive group selected from the group consisting of a vinyl group, a (meth)acrylic group, a styryl group, a (meth)acrylamide group, a vinyl ether group, an epoxy group, an oxetane group, a hydroxyl group, an amino group, an aldehyde group and a carboxyl group; each of R¹ and R² independently represents a hydrogen atom, an aliphatic hydrocarbon group that may have a substituent, an aryl group that may have a substituent, or a heterocyclic group that may have a substituent; and R¹ and R² may bond to each other to form a ring.)

Description

A polarizing plate provided with a resin composition for protecting a polarizer and a protective layer formed from the composition.

The present invention relates to a resin composition for protecting a polarizer and a polarizing plate including a protective layer formed from the composition.

The polarizer is typically produced by dyeing a polyvinyl alcohol (PVA) -based resin film with a dichroic substance such as iodine (for example, Patent Documents 1 and 2). It is known that in a moist heat environment, the iodine complex is destroyed by moisture absorption, and iodine is eluted to reduce the degree of polarization and increase the transmittance (color loss). Since water penetrates from the end of the polarizing plate, color loss tends to be remarkable at the end of the polarizer.

The polarizer is typically used as a polarizing plate including the polarizer and protective layers provided on both sides of the polarizer. In recent years, due to the demand for thinning, thinning of a polarizing element and a protective layer, and a polarizing plate having a protective layer on only one side of the polarizing element have been proposed. In such a configuration, the absorption of water from the end portion becomes faster, and the color loss of the end portion may become more remarkable. Further, if the protective layer is thin, the durability may be lowered and the polarizer may not be properly protected. As a highly durable protective layer, a protective layer using an epoxy resin has been proposed (for example, Patent Documents 3 to 5). However, when the epoxy resin is used alone as the protective layer, there is room for improvement in the adhesion to the polarizer and the pressure-sensitive adhesive layer, and there is a problem that it is difficult to put it into practical use.

Japanese Patent No. 5048120 Japanese Unexamined Patent Publication No. 2013-156391 Japanese Unexamined Patent Publication No. 2016-0853669 Japanese Unexamined Patent Publication No. 2016-004205 Japanese Patent No. 5454857

The present invention has been made to solve the above-mentioned conventional problems, and its main purpose is to have excellent adhesion to a polarizing element, to prevent color loss from the end portion, and to prevent problems such as whitening of the protective layer. It is an object of the present invention to provide a resin composition for protecting a polarizer that can be prevented, and a polarizing plate including a protective layer formed from the resin composition.

The resin composition for protecting a polarizer of the present invention comprises (A) an acrylic monomer having a weight of more than 50 parts by weight and a monomer represented by the formula (1) having a weight of more than 0 parts by weight and less than 50 parts by weight. The polymer obtained by polymerizing the above and (B) epoxy resin are contained. The content ratio of the polymer (A) and the epoxy resin (B) is 95: 5 to 60:40 or 40:60 to 1:99 by weight:

(In the formula, X is a group consisting of a vinyl group, a (meth) acrylic group, a styryl group, a (meth) acrylamide group, a vinyl ether group, an epoxy group, an oxetane group, a hydroxyl group, an amino group, an aldehyde group, and a carboxyl group. Represents a functional group containing at least one reactive group selected, R ¹ and R ² each independently have a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent, and a substituent. It represents an aryl group which may be used, or a heterocyclic group which may have a substituent, and R ¹ and R ² may be linked to each other to form a ring).
In one embodiment, the epoxy resin (B) is an epoxy resin having an aromatic ring.
In one embodiment, the polymer (A) and the epoxy resin (B) have a weight average molecular weight of 20,000 or more.
In one embodiment, the reactive group is at least one selected from the group consisting of (meth) acrylic groups and (meth) acrylamide groups.
In another aspect of the invention, a polarizing plate is provided. The polarizing plate includes a polarizing element and a protective layer formed from the polarizer protective resin composition on at least one surface of the polarizing element.
In one embodiment, the protective layer has a thickness of 0.1 μm to 8 μm.
In one embodiment, the polarizer has an iodine content of 2% to 25% by weight.
In one embodiment, the thickness of the polarizer is 8 μm or less.

According to the present invention, a resin composition for protecting a polarizing element, which has excellent adhesion to a polarizing element and can prevent problems such as color loss from an end and whitening of a protective layer, and the resin composition A polarizing plate having a formed protective layer is provided. The layer (protective layer) formed from the resin composition for protecting a polarizer of the present invention can sufficiently adhere to the polarizer and prevent the occurrence of appearance defects such as floating and peeling. Furthermore, whitening of the protective layer itself can be prevented. In addition, it is possible to prevent the intrusion of moisture from the end portion and prevent color loss from the end portion of the polarizer. Further, when the pressure-sensitive adhesive layer is formed on the protective layer, the anchoring force of the pressure-sensitive adhesive layer can be improved. As a result, it is possible to obtain a polarizing plate (polarizing plate with a protective layer) that has both the adhesion between the polarizing element and the protective layer and the excellent anchoring force of the pressure-sensitive adhesive layer formed on the protective layer.

It is the schematic sectional drawing of the polarizing plate by one Embodiment of this invention.

Hereinafter, preferred embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

A. Resin composition for protecting a polarizer The resin composition for protecting a polarizer of the present invention is represented by an acrylic monomer exceeding 50 parts by weight and a formula (1) exceeding 0 parts by weight and less than 50 parts by weight. It contains a polymer (A) obtained by polymerizing a monomer (hereinafter, also referred to as a polymer (A)) and an epoxy resin (B). The content ratio of the polymer (A) and the epoxy resin (B) of the resin composition for protecting the polarizer is 95: 5 to 60:40 or 40:60 to 1:99 by weight:

(In the formula, X is a group consisting of a vinyl group, a (meth) acrylic group, a styryl group, a (meth) acrylamide group, a vinyl ether group, an epoxy group, an oxetane group, a hydroxyl group, an amino group, an aldehyde group, and a carboxyl group. Represents a functional group containing at least one reactive group selected, R ¹ and R ² each independently have a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent, and a substituent. It represents an aryl group which may be used, or a heterocyclic group which may have a substituent, and R ¹ and R ² may be linked to each other to form a ring).

The content ratio of the polymer (A) and the epoxy resin (B) in the resin composition for protecting a polarizer is 95: 5 to 60:40 or 40:60 to 1:99 by weight. When the content ratio of the polymer (A) and the epoxy resin (B) is within the above range, the resin for protecting the polarizer is excellent in adhesion to the polarizer and can prevent color loss from the end of the polarizer. The composition is obtained. Further, when the content ratio of the polymer (A) and the epoxy resin (B) is in the above range, the anchoring force of the pressure-sensitive adhesive layer can be improved when the pressure-sensitive adhesive layer is formed on the protective layer. As a result, it is possible to obtain a polarizing plate (polarizing plate with a protective layer) that has both the adhesion between the polarizing element and the protective layer and the anchoring force of the pressure-sensitive adhesive layer formed on the protective layer. The content ratio of the polymer (A) and the epoxy resin (B) is preferably 95: 5 to 80:20 or 20:80 to 5:95, more preferably 90:10 to 90: 10 to 50:20 by weight. It is 70:30 or 30:70 to 10:90. The closer the content ratio of the polymer (A) and the epoxy resin (B) is to equal parts (50:50), the more the protective layer may be whitened.

A-1. Polymer (A)
The polymer (A) is obtained by polymerizing an acrylic monomer having more than 50 parts by weight and a monomer represented by the formula (1) having more than 0 parts by weight and less than 50 parts by weight:

(In the formula, X is a group consisting of a vinyl group, a (meth) acrylic group, a styryl group, a (meth) acrylamide group, a vinyl ether group, an epoxy group, an oxetane group, a hydroxyl group, an amino group, an aldehyde group, and a carboxyl group. Represents a functional group containing at least one reactive group selected, R ¹ and R ² each independently have a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent, and a substituent. It represents an aryl group which may be used, or a heterocyclic group which may have a substituent, and R ¹ and R ² may be linked to each other to form a ring).

The polymer (A) typically has a structure represented by the following formula. By polymerizing the monomer represented by the formula (1) and the acrylic monomer component, the polymer (A) is a substituent containing boron in the side chain (for example, a repeating unit of k in the following formula). Has. As a result, the adhesion between the polarizer and the layer (protective layer) formed by using the resin composition for protecting the polarizer can be improved. The boron-containing substituent may be continuously contained in the polymer or may be randomly contained. Only one type of polymer (A) may be used, or two or more types may be used in combination.

(In the formula, R ⁶ represents an arbitrary functional group, and j and k represent integers of 1 or more).

The weight average molecular weight of the polymer (A) is preferably 10,000 or more, more preferably 20,000 or more, still more preferably 35,000 or more, and particularly preferably 50,000 or more. The weight average molecular weight of the polymer (A) is preferably 250,000 or less, more preferably 200,000 or less, and even more preferably 150,000 or less. When the weight average molecular weight of the polymer (A) is in the above range, the crack resistance of the layer (protective layer) formed by using the polarizer protective resin composition can be improved. The weight average molecular weight can be measured by, for example, GPC (solvent: dimethylformamide (DMF)).

The glass transition temperature of the polymer (A) is preferably 50 ° C. or higher, more preferably 60 ° C. or higher, and even more preferably 80 ° C. or higher. The glass transition temperature of the polymer (A) is preferably 300 ° C. or lower. When the glass transition temperature is in the above range, the crack resistance of the layer (protective layer) formed by using the resin composition for protecting a polarizer can be improved.

The polymer (A) includes an acrylic monomer exceeding 50 parts by weight, a monomer represented by the formula (1) exceeding 0 parts by weight and less than 50 parts by weight, a polymerization initiator, and any arbitrary material. It is obtained by polymerizing a monomer composition containing another monomer by an arbitrary suitable polymerization method. Solution polymerization is preferably used as the polymerization method. By polymerizing the polymer (A) by solution polymerization, a higher molecular weight polymer can be obtained.

A-1-1. Acrylic monomer Any suitable acrylic monomer can be used as the acrylic monomer. For example, a (meth) acrylic acid ester-based monomer having a linear or branched structure and a (meth) acrylic acid ester-based monomer having a cyclic structure can be mentioned. As used herein, (meth) acrylic refers to acrylic and / or methacrylic.

Examples of the (meth) acrylic acid ester-based monomer having a linear or branched structure include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, and (meth) acrylic acid. Examples thereof include isopropyl, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, methyl 2-ethylhexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate and the like. .. Preferably, methyl (meth) acrylate is used. As the (meth) acrylic acid ester-based monomer, only one type may be used, or two or more types may be used in combination.

Examples of the (meth) acrylate-based monomer having a cyclic structure include cyclohexyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, 1-adamantyl (meth) acrylate, ( Dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentanyl (meth) acrylate, biphenyl (meth) acrylate, o-biphenyloxyethyl (meth) acrylate, o-biphenyloxyethoxy Ethyl (meth) acrylate, m-biphenyloxyethyl acrylate, p-biphenyloxyethyl (meth) acrylate, o-biphenyloxy-2-hydroxypropyl (meth) acrylate, p-biphenyloxy-2-hydroxypropyl (meth) acrylate , M-biphenyloxy-2-hydroxypropyl (meth) acrylate, N- (meth) acryloyloxyethyl-o-biphenyl = carbamate, N- (meth) acryloyloxyethyl-p-biphenyl = carbamate, N- (meth) Examples thereof include biphenyl group-containing monomers such as acryloyloxyethyl-m-biphenyl = carbamate and o-phenylphenol glycidyl ether acrylate, terphenyl (meth) acrylate, and o-terphenyloxyethyl (meth) acrylate. Preferably, 1-adamantyl (meth) acrylate and dicyclopentanyl (meth) acrylate are used. By using these monomers, a polymer having a high glass transition temperature can be obtained. Only one of these monomers may be used, or two or more of these monomers may be used in combination. In addition, in this specification, (meth) acryloyl means an acryloyl group and / or a methacryloyl group.

Further, instead of the above (meth) acrylic acid ester-based monomer, a silsesquioxane compound having a (meth) acryloyl group may be used. By using the silsesquioxane compound, an acrylic polymer having a high glass transition temperature can be obtained. The silsesquioxane compound is known to have various skeletal structures, for example, a basket-shaped structure, a ladder-shaped structure, and a random structure. The silsesquioxane compound may have only one of these structures, or may have two or more of these structures. Only one type of silsesquioxane compound may be used, or two or more types may be used in combination.

As the silsesquioxane compound having a (meth) acryloyl group, for example, MAC grade and AC grade of Toagosei Co., Ltd. SQ series can be used. The MAC grade is a silsesquioxane compound containing a methacryloyl group, and specific examples thereof include MAC-SQ TM-100, MAC-SQ SI-20, and MAC-SQ HDM. The AC grade is a silsesquioxane compound containing an acryloyl group, and specific examples thereof include AC-SQ TA-100 and AC-SQ SI-20.

Acrylic monomer is used in excess of 50 parts by weight. The acrylic monomer is used so that the total amount of the acrylic monomer and the monomer described later is 100 parts by weight.

A-1-2. Monomer As the monomer, a monomer represented by the formula (1) is used. By using such a monomer, a substituent containing boron is introduced into the side chain of the polymer (A). Therefore, the adhesion between the polarizer composed of a PVA-based resin and the layer (protective layer) formed by using the resin composition for protecting the polarizer can be improved. Further, the water resistance of the layer (protective layer) itself formed by using the resin composition for protecting the polarizer is also improved, and color loss from the end portion of the polarizer can be prevented. Only one type of monomer may be used, or two or more types may be used in combination.

(In the formula, X is a group consisting of a vinyl group, a (meth) acrylic group, a styryl group, a (meth) acrylamide group, a vinyl ether group, an epoxy group, an oxetane group, a hydroxyl group, an amino group, an aldehyde group, and a carboxyl group. Represents a functional group containing at least one reactive group selected, R ¹ and R ² each independently have a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent, and a substituent. It represents an aryl group which may be used, or a heterocyclic group which may have a substituent, and R ¹ and R ² may be linked to each other to form a ring).

The aliphatic hydrocarbon group includes a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, and a cyclic alkyl group having 3 to 20 carbon atoms which may have a substituent. , Alkyl groups having 2 to 20 carbon atoms can be mentioned. Examples of the aryl group include a phenyl group having 6 to 20 carbon atoms which may have a substituent and a naphthyl group having 10 to 20 carbon atoms which may have a substituent. Examples of the heterocyclic group include a 5-membered ring group or a 6-membered ring group containing at least one heteroatom which may have a substituent. R ¹ and R ² may be connected to each other to form a ring. R ¹ and R ² are preferably a hydrogen atom or a linear or branched alkyl group having 1 to 3 carbon atoms, and more preferably a hydrogen atom.

The reactive groups contained in the functional group represented by X are vinyl group, (meth) acrylic group, styryl group, (meth) acrylamide group, vinyl ether group, epoxy group, oxetan group, hydroxyl group, amino group and aldehyde group. , And at least one selected from the group consisting of carboxyl groups. Preferably, the reactive group is a (meth) acrylic group and / or a (meth) acrylamide group. By having these reactive groups, the adhesion between the polarizer and the layer (protective layer) formed by using the resin composition for protecting the polarizer can be improved.

In one embodiment, the functional group represented by X is preferably a functional group represented by the following formula.

(In the formula, Z is a group consisting of a vinyl group, a (meth) acrylic group, a styryl group, a (meth) acrylamide group, a vinyl ether group, an epoxy group, an oxetane group, a hydroxyl group, an amino group, an aldehyde group, and a carboxyl group. Represents a functional group containing at least one reactive group selected, where Y represents a phenylene group or an alkylene group).

Specifically, the following compounds can be used as the monomer represented by the general formula (1).

The monomer represented by the formula (1) is used in a content of more than 0 parts by weight and less than 50 parts by weight. It is preferably 0.01 parts by weight or more and less than 50 parts by weight, more preferably 0.05 parts by weight to 20 parts by weight, and further preferably 0.1 parts by weight to 10 parts by weight. If the content of the monomer exceeds 50 parts by weight, color loss from the end portion may easily occur.

A-1-3. Polymerization Initiator As the polymerization initiator, any suitable polymerization initiator can be used. For example, peroxides such as benzoyl peroxide, lauroyl peroxide and sodium peroxide; hydroperoxides such as t-butyl hydroperoxide and cumene hydroperoxide; azo compounds such as azobisisobutyronitrile; and the like can be mentioned. Only one type of polymerization initiator may be used, or two or more types may be used.

As the content of the polymerization initiator, any appropriate amount can be used. The content of the polymerization initiator is preferably 0.1 parts by weight to 5 parts by weight, and more preferably 0.3 parts by weight to 2 parts by weight.

A-1-4. Polymerization Method As described above, the polymer (A) is preferably obtained by solution-polymerizing a monomer component such as an acrylic monomer and a monomer represented by the formula (1). Any suitable solvent can be used as the solvent used in the solution polymerization. For example, water; alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol; aromatic or aliphatic hydrocarbons such as benzene, toluene, xylene, cyclohexane and n-hexane; ester compounds such as ethyl acetate; ketones such as acetone and methyl ethyl ketone. Compounds: Cyclic ether compounds such as tetrahydrofuran and dioxane can be mentioned. Only one of these solvents may be used, or two or more of these solvents may be used in combination. Moreover, you may use the organic solvent and water together.

The polymerization reaction can be carried out at any suitable temperature and time. For example, the polymerization reaction can be carried out in the range of 50 ° C. to 100 ° C., preferably 60 ° C. to 80 ° C. The reaction time is, for example, 1 hour to 8 hours, preferably 3 hours to 5 hours.

A-2. Epoxy resin (B)
As the epoxy resin (B), any suitable epoxy resin can be used. As the epoxy resin (B), an epoxy resin having an aromatic ring is preferably used. By using an epoxy resin having an aromatic ring as the epoxy resin (B), a resin composition for protecting a polarizer, which is more excellent in adhesion to a polarizer and can prevent color loss from the end of the polarizer, can be obtained. Get it. Further, when the pressure-sensitive adhesive layer is formed on the protective layer, the anchoring force of the pressure-sensitive adhesive layer can be improved. Examples of the epoxy resin having an aromatic ring include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin and other bisphenol type epoxy resins; phenol novolac epoxy resin, cresol novolac epoxy resin, hydroxybenzaldehyde phenol novolac. Novolak type epoxy resin such as epoxy resin; polyfunctional epoxy resin such as tetrahydroxyphenylmethane glycidyl ether, tetrahydroxybenzophenone glycidyl ether, epoxidized polyvinylphenol, naphthol type epoxy resin, naphthalene type epoxy resin, biphenyl type Epoxy resin and the like can be mentioned. Preferably, a bisphenol A type epoxy resin, a biphenyl type epoxy resin, or a bisphenol F type epoxy resin is used. By using these epoxy resins, color loss from the end of the polarizer can be further prevented. Only one type of epoxy resin may be used, or two or more types may be used in combination.

The epoxy resin (B) preferably has a weight average molecular weight (Mw) of 20,000 or more, more preferably 30,000 or more, and further preferably 37,000 or more. When the weight average molecular weight of the epoxy resin (B) is in the above range, it is possible to further prevent color loss from the end of the polarizer. The weight average molecular weight can be measured, for example, by GPC.

A-3. Other Ingredients In addition to the polymer (A) and the epoxy resin (B), the resin composition for protecting a polarizer may contain any other suitable ingredient. Other components include, for example, solvents and additives. As the solvent, a solvent that can be used for solution polymerization of the polymer (A) may be used, or another solvent may be used. As the other solvent, ethyl acetate, toluene, methyl ethyl ketone and cyclopentanone are preferably used. Only one of these solvents may be used, or two or more of these solvents may be used in combination.

Any suitable additive can be used as the additive. For example, surfactants, ultraviolet absorbers, antioxidants, tackifiers and the like can be mentioned. Only one type of additive may be used, or two or more types may be used in combination. These additives can be used in any suitable amount.

A-4. Method for Preparing Resin Composition for Protecting the Polarizer The resin composition for protecting the polarizer can be prepared by any suitable method. For example, it can be prepared by mixing the polymer (A), the epoxy resin (B), and optionally any suitable additive in any suitable solvent. Further, when the polymer (A) is polymerized by solution polymerization, it may be prepared by adding the epoxy resin (B) and any appropriate additive to the polymerization solution of the polymer (A) and mixing them. Good.

B. Polarizing plate The polarizing plate of the present invention includes a polarizing element and a protective layer formed from the resin composition for protecting the polarizer on at least one surface of the polarizing element. The protective layer formed from the resin composition for protecting the polarizer has excellent adhesion to the polarizer. Therefore, even when the thickness of the polarizer is thin, it is possible to prevent appearance defects such as floating and peeling of the protective layer from the polarizer. In addition, color loss from the end of the polarizer can be prevented. Further, the protective layer formed from the above resin composition for protecting a polarizer can improve the anchoring force of the pressure-sensitive adhesive layer when the pressure-sensitive adhesive layer is formed on the protective layer. As a result, it is possible to obtain a polarizing plate (polarizing plate with a protective layer) that has both the adhesion between the polarizing element and the protective layer and the anchoring force of the pressure-sensitive adhesive layer formed on the protective layer.

B-1. Outline of Polarizing Plate FIG. 1 is a schematic cross-sectional view of a polarizing plate according to one embodiment of the present invention. The polarizing plate 100 of the illustrated example includes a polarizing element 10 and a protective layer 20 formed on at least one surface of the polarizing element. The protective layer 20 is a layer formed from the above resin composition for protecting a polarizer. By forming the protective layer from the resin composition for protecting the polarizer, the adhesion between the protective layer and the polarizer is improved. Therefore, it is possible to prevent the intrusion of moisture from the end portion of the polarizing plate and prevent the color from coming off from the end portion. Further, since the protective layer 20 is also excellent in crack resistance, the polarizer 10 can be appropriately protected. Further, the protective layer 20 can prevent color loss of the polarizer from the end portion even when the protective layer 20 is formed on only one side of the polarizer 10. Therefore, it can also contribute to reducing the thickness of the polarizing plate 100. In the illustrated example, the protective layer 20 is formed only on one surface of the polarizer 10, but the protective layers 20 may be formed on both sides of the polarizer 10. Further, the protective layer 20 may be formed on one surface of the polarizer 10, and another protective layer may be formed on the other surface of the polarizer 10. The protective layer 20 is typically formed directly on the polarizer 10 (without an adhesive layer or an adhesive layer). By forming the protective layer directly on the polarizer, it can contribute to the thinning of the polarizing plate. Further, by directly forming the protective layer, the adhesion between the polarizer and the protective layer can be improved.

The polarizing plate 100 may further include any suitable functional layer other than the protective layer 20 depending on the purpose. Examples of the functional layer include a retardation layer, a light diffusion layer, an antireflection layer, and a reflection type polarizer. The functional layer may be laminated on the side of the polarizer 10 or may be laminated on the side of the protective layer 20. Further, a plurality of functional layers may be included.

B-2. Polarizer A polarizing element is typically a resin film containing a dichroic substance. Examples of the dichroic substance include iodine and organic dyes. Only one type of dichroic substance may be used, or two or more types may be used in combination. It preferably contains iodine.

In one embodiment, the polarizer 10 preferably has an iodine content of 2% to 25% by weight. In another embodiment of the invention, the polarizer 10 preferably has an iodine content of 10% to 25% by weight, more preferably 15% to 25% by weight. Polarizers with a high iodine content can be more prominent in color loss in a moist heat environment. Therefore, the effect of forming the protective layer using the above-mentioned resin composition for protecting a polarizer can be more exerted. As used herein, the term "iodine content" means the amount of all iodine contained in the polarizer (PVA-based resin film). More specifically, iodine during polarizers iodide ion (I ^-), molecular iodine (I _2), polyiodine ion _{^{(I 3 -, I 5 -}} ) where present in the form of such, herein Iodine content means the amount of iodine that includes all of these forms. The iodine content can be calculated, for example, by the calibration curve method of fluorescent X-ray analysis. The polyiodine ion exists in a state in which a PVA-iodine complex is formed in the polarizer. By forming such a complex, absorption dichroism can be exhibited in the wavelength range of visible light. Specifically, a complex of PVA and tri-iodide ion (PVA · _{I 3} ^-) has a light absorption peak around 470 nm, a complex of PVA and five iodide ion (PVA · _{I 5} ^-) is 600nm near Has an absorption peak at. As a result, polyiodine ions can absorb light in a wide range of visible light, depending on their morphology. On the other hand, iodine ion (I ⁻ ) has an absorption peak near 230 nm and is not substantially involved in the absorption of visible light. Therefore, polyiodine ions present in the form of a complex with PVA may be mainly involved in the absorption performance of the polarizer.

The thickness of the polarizer is preferably 8 μm or less, more preferably 0.6 μm or more and less than 8 μm. In one embodiment, the thickness of the polarizer is preferably 5 μm or less. On the other hand, the thickness of the polarizer is preferably 0.6 μm or more, more preferably 1.0 μm or more.

The single transmittance of the polarizer is, for example, 30% or more. The theoretical upper limit of the simple substance transmittance is 50%, and the practical upper limit is 46%. The single transmittance (Ts) is a Y value measured by a two-degree field of view (C light source) of JIS Z8701 and corrected for luminosity factor. For example, a spectrophotometer with an integrating sphere (manufactured by JASCO Corporation). It can be measured using the product name: V7100).

Further, the degree of polarization of the polarizer is, for example, 99.0% or more, preferably 99.5% or more, and more preferably 99.9% or more. As described above, the polarizing plate of the present invention can prevent color loss from the end portion. Therefore, even when the degree of polarization of the polarizer is high, the degree of polarization can be maintained satisfactorily.

B-2-1. Method for Producing Polarizer The polarizer can be manufactured by any suitable method. For example, it can be produced by subjecting a PVA-based resin film to a swelling step, a dyeing step, a cross-linking step, a stretching step, a washing step, and a drying step. In one embodiment, the PVA-based resin film may be a PVA-based resin layer formed on a substrate. The laminate of the base material and the resin layer can be obtained, for example, by a method of applying the coating liquid containing the PVA-based resin to the base material, a method of laminating a PVA-based resin film on the base material, or the like. As the base material, any suitable resin base material can be used, and for example, a thermoplastic resin base material can be used.

B-2-1-1. PVA-based resin film Examples of the PVA-based resin forming the PVA-based resin film include polyvinyl alcohol and an ethylene-vinyl alcohol copolymer. Polyvinyl alcohol is obtained by saponification of polyvinyl acetate. The ethylene-vinyl alcohol copolymer is obtained by saponifying the ethylene-vinyl acetate copolymer. The degree of saponification of the PVA-based resin is usually 85 mol% or more and less than 100 mol%, preferably 95.0 mol% to 99.99 mol%, and more preferably 99.0 mol% to 99.99 mol%. is there. The degree of saponification can be determined according to JIS K 6726-1994. By using a PVA-based resin having such a degree of saponification, a polarizer having excellent durability can be obtained.

The average degree of polymerization of the PVA-based resin can be appropriately selected according to the purpose. The average degree of polymerization is usually 1000 to 10000, preferably 1200 to 4500, and more preferably 1500 to 4300. The average degree of polymerization can be determined according to JIS K 6726-1994.

The thickness of the PVA-based resin film can be set according to the desired thickness of the polarizer. The thickness of the PVA-based resin film is, for example, 0.5 μm to 200 μm. By using the dyeing solution described later, for example, even if the PVA-based resin film is less than 10 μm, it can be sufficiently dyed in a short time, and the property of being able to sufficiently function as a polarizer can be imparted.

As described above, the polarizer can be produced, for example, by subjecting a PVA-based resin film to a swelling step, a dyeing step, a cross-linking step, a stretching step, a washing step, and a drying step. Each step is performed at an arbitrary appropriate timing. Further, if necessary, any step other than the dyeing step may be omitted, a plurality of steps may be performed at the same time, and each step may be performed a plurality of times. Hereinafter, each step will be described.

B-2-1-2. Stretching In the stretching treatment, the PVA-based resin film is typically uniaxially stretched 3 to 7 times the original length. In one embodiment, the PVA-based resin film is subjected to dry stretching. Dry stretching is preferable because the stretching treatment can be performed in a wider temperature range. The temperature at which the dry stretching is performed is, for example, 50 ° C. to 200 ° C., preferably 80 ° C. to 180 ° C., and more preferably 90 ° C. to 160 ° C. The stretching direction may be the longitudinal direction of the film (MD direction) or the width direction of the film (TD direction). The stretching direction can correspond to the absorption axis direction of the obtained polarizer.

B-2-1-3. Dyeing The dyeing step is a step of dyeing a PVA-based resin film with a dichroic substance. It is preferably carried out by adsorbing a dichroic substance. Examples of the adsorption method include a method of immersing a PVA-based resin film in a dyeing solution containing a bicolor substance, a method of applying the dyeing solution to the PVA-based resin film, and a method of spraying the dyeing solution onto the PVA-based resin film. The method of doing this can be mentioned. A method of immersing the PVA-based resin film in the dyeing solution is preferable. This is because the dichroic substance can be adsorbed well.

Examples of the dichroic substance include iodine and a dichroic dye as described above. Iodine is preferred. When iodine is used as the dichroic substance, an aqueous iodine solution is preferably used as the staining solution. The iodine content of the iodine aqueous solution is preferably 0.04 parts by weight to 5.0 parts by weight with respect to 100 parts by weight of water. In one embodiment, the iodine content in the iodine aqueous solution is preferably 0.3 parts by weight or more with respect to 100 parts by weight of water. In order to increase the solubility of iodine in water, it is preferable to add iodide to the aqueous iodine solution. Potassium iodide is preferably used as the iodide. The content of iodide is preferably 0.3 to 15 parts by weight with respect to 100 parts by weight of water.

The temperature of the dyeing solution at the time of dyeing can be set to any appropriate value. For example, it is 20 ° C to 50 ° C. When the PVA-based resin film is immersed in the dyeing solution, the immersion time is, for example, 1 second to 1 minute.

The content of iodide contained in the dyeing solution is preferably 1 part by weight to 40 parts by weight, and more preferably 3 parts by weight to 30 parts by weight with respect to 100 parts by weight of the solvent. When the content of iodide is in the above range, sufficient polyiodine ions can be formed in the dyeing solution. Examples of iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide. And so on. Potassium iodide is preferred.

Any suitable solvent can be used as the solvent for the dyeing solution, and water is usually used.

B-2-1-4. Swelling The swelling step is usually performed before the dyeing step. In one embodiment, the swelling step may be performed with the dyeing step in the same immersion bath. The swelling step is performed, for example, by immersing a PVA-based resin film in a swelling bath. As the swelling bath, any suitable liquid can be used, and for example, water such as distilled water or pure water is used. The swelling bath may contain any suitable other ingredients other than water. Examples of other components include solvents such as alcohol, additives such as surfactants, and iodides. Examples of the iodide include those exemplified above. Preferably, potassium iodide is used. The temperature of the swelling bath is, for example, 20 ° C to 45 ° C. The immersion time is, for example, 10 seconds to 300 seconds.

B-2-1-5. Cross-linking In the cross-linking step, a boron compound is usually used as a cross-linking agent. Examples of the boron compound include boric acid and borax. Preferably, it is boric acid. In the cross-linking step, the boron compound is usually used in the form of an aqueous solution.

When an aqueous boric acid solution is used, the boric acid concentration of the aqueous boric acid solution is, for example, 2% by weight to 15% by weight, preferably 3% by weight to 13% by weight. The boric acid aqueous solution may further contain an iodide such as potassium iodide and a zinc compound such as zinc sulfate and zinc chloride.

The cross-linking step can be performed by any suitable method. For example, a method of immersing a PVA-based resin film in an aqueous solution containing a boron compound, a method of applying an aqueous solution containing a boron compound to a PVA-based resin film, or a method of spraying an aqueous solution containing a boron compound onto a PVA-based resin film can be mentioned. Be done. It is preferable to immerse in an aqueous solution containing a boron compound.

The temperature of the solution used for crosslinking is, for example, 25 ° C. or higher, preferably 30 ° C. to 85 ° C., and more preferably 40 ° C. to 70 ° C. The immersion time is, for example, 5 seconds to 800 seconds, preferably 8 seconds to 500 seconds.

B-2-1-6. Cleaning The cleaning step is performed using water or an aqueous solution containing the above iodide. This is typically done by immersing a PVA-based resin film in an aqueous potassium iodide solution. The temperature of the aqueous solution in the washing step is, for example, 5 ° C to 50 ° C. The immersion time is, for example, 1 second to 300 seconds.

B-2-1-7. Drying The drying step can be performed by any suitable method. For example, natural drying, blast drying, vacuum drying, heat drying and the like can be mentioned, and heat drying is preferably used. When heat-drying is performed, the heating temperature is, for example, 30 ° C. to 100 ° C. The drying time is, for example, 10 seconds to 10 minutes.

B-3. Protective layer The protective layer 20 is formed on at least one surface of the polarizer 10. The protective layer 20 is formed by using the above resin composition for protecting a polarizer.

The thickness of the protective layer 20 can be set to an arbitrary appropriate value according to the thickness of the polarizer and the glass transition temperature of the polymer. In one embodiment, the thickness of the protective layer is preferably 0.1 μm to 8 μm, more preferably 0.2 μm to 3 μm, and even more preferably 0.5 μm to 1 μm. When the thickness of the protective layer is within the above range, it can contribute to the thinning of the polarizing plate. As described above, the protective layer 20 can appropriately protect the polarizer 10 and prevent color loss from the end portion even when the thickness is thin. If the thickness of the protective layer 20 exceeds 8 μm, the adhesion between the polarizer and the protective layer may decrease.

The elastic modulus of the cross section of the protective layer 20 is preferably 4 GPa to 8 GPa, and more preferably 5 GPa to 6 GPa. When the elastic modulus is in the above range, it is possible to prevent the occurrence of cracks in the protective layer. Therefore, the polarizer can be appropriately protected even when the thickness is thin. In the present specification, the elastic modulus of the cross section of the protective layer can be measured by the method described in Examples described later.

Moisture permeability of the protective layer is preferably ^{10g / m 2 · 24h ~ 2000g} / m 2 · 24h, more preferably from ^{100g / m 2 · 24h ~ 1800g} / m 2 · 24h, more preferably 150 g / m a ^{2 · 24h ~ 1500g / m 2} · 24h. When the moisture permeability is in the above range, it is possible to prevent moisture from entering and causing color loss in the polarizer.

The protective layer can be formed by any suitable method. For example, it can be formed by applying the resin composition for protecting a polarizer to the polarizer. Various coating methods include bar coater coating, air knife coating, gravure coating, gravure reverse coating, reverse roll coating, lip coating, die coating, dip coating, offset printing, flexographic printing, screen printing, etc. Method can be adopted. Further, any appropriate surface modification treatment may be applied to the surface to which the polarizing element protective resin composition of the polarizer is applied.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.

[Production Example 1] Preparation of UV-curable adhesive 40 parts by weight of N-hydroxyethylacrylamide (HEAA), 60 parts by weight of acryloylmorpholin (ACMO), and photoinitiator (manufactured by BASF, trade name: IRGACURE 819) 3 A part by weight was mixed to prepare an ultraviolet curable adhesive.

[Production Example 2] Preparation of Polarizer 1 As a thermoplastic resin base material, an amorphous isophthalic acid copolymer polyethylene terephthalate (IPA copolymer PET) film (thickness: 100 μm) having a water absorption rate of 0.75% and a Tg of 75 ° C. is used. Using. One side of the base material is corona-treated, and polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (polymerization degree 1200, acetoacetyl-modification degree 4.6) are applied to the corona-treated surface. %, Degree of polymerization 99.0 mol% or more, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name: Gosefimer Z200) is applied and dried at 25 ° C., and PVA having a thickness of 5 μm is applied. A based resin layer was formed to prepare a laminate.
The obtained laminate was stretched 4.5 times in the air at 140 ° C. in a direction orthogonal to the longitudinal direction of the laminate using a tenter stretching machine (stretching treatment).
Next, the laminate was immersed in an insolubilizing bath at a liquid temperature of 30 ° C. (an aqueous boric acid solution obtained by blending 4 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (insolubilization treatment).
Next, the laminate was dyed by immersing it in a dyeing solution at 30 ° C. (an aqueous solution in which 12.0 parts by weight of potassium iodide and 1.0 part by weight of solid iodine were added to 100 parts by weight of water) for 6 seconds ( Dyeing process).
Next, it was immersed in a cross-linked bath at a liquid temperature of 60 ° C. (an aqueous boric acid solution obtained by blending 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with respect to 100 parts by weight of water) for 35 seconds. (Crossing treatment).
Then, the laminate was immersed in a washing bath at a liquid temperature of 25 ° C. (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) for 10 seconds (washing treatment).
Then, it was dried in an oven at 60 ° C. for 60 seconds to obtain a laminate 1 having a PVA-based resin layer (polarizer) having a thickness of 1.2 μm.
The ultraviolet curable adhesive is applied to the surface of the obtained laminate 1 on the polarizer side so that the thickness after curing is 1 μm, and the (meth) acrylic resin film A having a lactone ring structure on the applied surface. The corona-treated surfaces (thickness 40 μm) were bonded together to cure the ultraviolet curable adhesive. Then, the PET film was peeled off from the laminate to obtain a single-protective polarizer laminate 1 (protective layer (40 μm) / adhesive layer (1 μm) / polarizer (1.2 μm)).

[Production Example 3] Preparation of Polarizer 2 As a base material, an amorphous isophthalic acid copolymer polyethylene terephthalate (IPA copolymer PET) film (thickness: 100 μm) having a water absorption rate of 0.75% and a Tg of 75 ° C. ) Was used. One side of the base material is corona-treated, and polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (polymerization degree 1200, acetoacetyl-modification degree 4.6) are applied to the corona-treated surface. %, Degree of polymerization 99.0 mol% or more, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name: Gosefimer Z200) is applied and dried at 25 ° C., and PVA having a thickness of 13 μm is applied. A based resin layer was formed to prepare a laminate.
The obtained laminate was stretched 2.4 times in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds in an oven at 130 ° C. (aerial auxiliary stretching).
Next, the laminate was immersed in an insolubilizing bath at a liquid temperature of 40 ° C. (an aqueous boric acid solution obtained by blending 4 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (insolubilization treatment).
Next, the laminate was mixed with a staining solution at 30 ° C. (an aqueous solution obtained by adding 7.0 parts by weight of potassium iodide and 1.0 part by weight of solid iodine to 100 parts by weight of water) to obtain the transmittance of the polarizer. Was dyed by immersing it so that the content was 42% or more (dyeing treatment).
Then, it was immersed in a cross-linked bath at a liquid temperature of 40 ° C. (an aqueous boric acid solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) for 35 seconds. (Crossing treatment).
Then, while immersing the laminate in a boric acid aqueous solution (boric acid concentration: 4.0% by weight) having a liquid temperature of 70 ° C., the total draw ratio was 5. in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds. The uniaxial stretching was performed so as to be 5 times (stretching in water).
Then, the laminate was immersed in a washing bath at a liquid temperature of 20 ° C. (an aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water) for 3 seconds (cleaning treatment).
Then, it was dried in an oven at 60 ° C. for 60 seconds to obtain a laminate 2 having a PVA-based resin layer (polarizer) having a thickness of 5 μm.
A polarizer laminate 2 (protective layer (40 μm) / adhesive layer (1 μm) / polarizer (5 μm)) was obtained in the same manner as in Production Example 2 except that the obtained laminate 2 was used.

[Production Example 4] Preparation of Polymer (A) -1 Methyl methacrylate (MMA, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name: methyl methacrylate monomer) 99.0 parts by weight, represented by the general formula (1) Monomer (monomer of general formula (1e)) 1.0 part by weight, polymerization initiator (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name: 2,2'-azobis (isobutyronitrile)) 0. 2 parts by weight was dissolved in 100 parts by weight of toluene. Next, a polymerization reaction was carried out for 5 hours while heating at 70 ° C. in a nitrogen atmosphere to obtain a polymer (A) -1 (solid content concentration: 50% by weight). The weight average molecular weight of the obtained polymer (A) -1 was 50,000.

[Production Example 5] Preparation of Polymer (A) -2 Methyl methacrylate (MMA, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name: methyl methacrylate monomer) 97.0 parts by weight, represented by the general formula (1) Monomer (monomer of general formula (1e)) 3.0 parts by weight, polymerization initiator (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name: 2,2'-azobis (isobutyronitrile)) 0. 2 parts by weight was dissolved in 200 parts by weight of toluene. Next, a polymerization reaction was carried out for 5 hours while heating at 70 ° C. in a nitrogen atmosphere to obtain a polymer (A) -2 (solid content concentration: 33% by weight). The weight average molecular weight of the obtained polymer (A) -2 was 85,000.

[Production Example 6] Preparation of Polymer (A) -3 Methyl methacrylate (MMA, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name: methyl methacrylate monomer) 90.0 parts by weight, represented by the general formula (1) Monomer (monomer of general formula (1e)) 10.0 parts by weight, polymerization initiator (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name: 2,2'-azobis (isobutyronitrile)) 0. 2 parts by weight was dissolved in 200 parts by weight of toluene. Next, a polymerization reaction was carried out for 5 hours while heating at 70 ° C. in a nitrogen atmosphere to obtain a polymer (A) -3 (solid content concentration: 33% by weight). The weight average molecular weight of the obtained polymer (A) -3 was 87,000.

[Production Example 7] Preparation of Polymer (A) -4 Instead of the monomer represented by the general formula (1) (monomer of the general formula (1e)), it is represented by the general formula (1b). A polymer (A) -4 (solid content concentration: 50% by weight) was obtained in the same manner as in Production Example 4 except that a monomer was used. The weight average molecular weight of the obtained polymer (A) -4 was 50,000.

[Production Example 8] Preparation of Polymer (A) -5 Instead of the monomer represented by the general formula (1) (monomer of the general formula (1e)), it is represented by the general formula (1c). A polymer (A) -5 (solid content concentration: 50% by weight) was obtained in the same manner as in Production Example 4 except that a monomer was used. The weight average molecular weight of the obtained polymer (A) -5 was 50,000.

[Production Example 9] Preparation of Polymer (A) -6 Instead of the monomer represented by the general formula (1) (monomer of the general formula (1e)), it is represented by the general formula (1d). A polymer (A) -6 (solid content concentration: 50% by weight) was obtained in the same manner as in Production Example 4 except that a monomer was used. The weight average molecular weight of the obtained polymer (A) -6 was 50,000.

[Production Example 10] Preparation of Polymer (A) -7 Instead of the monomer represented by the general formula (1) (monomer of the general formula (1e)), it is represented by the general formula (1a). A polymer (A) -7 (solid content concentration: 50% by weight) was obtained in the same manner as in Production Example 4 except that a monomer was used. The weight average molecular weight of the obtained polymer (A) -7 was 50,000.

[Production Example 11] Preparation of Polymer (A) -8 Instead of the monomer represented by the general formula (1) (monomer of the general formula (1e)), it is represented by the general formula (1a). A polymer (A) -8 (solid content concentration: 33% by weight) was obtained in the same manner as in Production Example 5 except that a monomer was used. The weight average molecular weight of the obtained polymer (A) -8 was 85,000.

[Production Example 12] Preparation of Acrylic Adhesive In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a cooler, 99 parts by weight of butyl acrylate and 1 part by weight of 4-hydroxybutyl acrylate. A monomer mixture containing the above was charged. Further, with respect to 100 parts by weight of the above-mentioned monomer mixture (solid content), 0.1 part by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator was charged together with ethyl acetate, and nitrogen gas was added while gently stirring. After the introduction and substitution with nitrogen, the liquid temperature in the flask was maintained at around 60 ° C. and the polymerization reaction was carried out for 7 hours. Then, ethyl acetate was added to the obtained reaction solution to adjust the solid content concentration to 30%. In this way, a solution of an acrylic polymer (base polymer) having a weight average molecular weight of 1.4 million was prepared.
With respect to 100 parts by weight of the solid content of the above acrylic polymer solution, 0.095 parts by weight of trimethylolpropane xylylene diisocyanate (manufactured by Mitsui Chemicals, trade name: Takenate D110N) and 0.3 of dibenzoyl peroxide as a cross-linking agent. 0.2 parts by weight of organosilane (manufactured by Soken Kagaku Co., Ltd., trade name: A100) and thiol group-containing silane coupling agent (manufactured by Shinetsu Chemical Industry Co., Ltd., trade name: X41-1810) 0. An acrylic pressure-sensitive adhesive (solution) was obtained by blending 2 parts by weight and 0.3 parts by weight of an antioxidant (manufactured by BASF, trade name: Irganox1010).

[Example 1] Preparation of polarizing plate 1 90 parts by weight of polymer (A) -1 and 10 parts by weight of epoxy resin 1 (manufactured by Mitsubishi Chemical Corporation, trade name: jER (registered trademark) 1256B40) are mixed. Then, a resin composition for protecting the polarizer was prepared. The obtained resin composition for protecting a polarizer was applied to the surface of the polarizing element laminate 1 on the polarizer side so that the thickness after drying was 0.7 μm to form a protective layer, and a polarizing plate 1 was obtained.

[Example 2] Preparation of polarizing plate 2 Example 1 except that a resin composition for protecting a polarizer was prepared using 70 parts by weight of the polymer (A) -1 and 30 parts by weight of the epoxy resin 1. The polarizing plate 2 was obtained in the same manner as in the above.

[Example 3] Preparation of polarizing plate 3 A polarizing plate 3 was obtained in the same manner as in Example 1 except that 30 parts by weight of the polymer (A) -1 and 70 parts by weight of the epoxy resin 1 were mixed. ..

[Example 4] Preparation of polarizing plate 4 A polarizing plate 4 was obtained in the same manner as in Example 1 except that 10 parts by weight of the polymer (A) -1 and 90 parts by weight of the epoxy resin 1 were mixed. ..

[Example 5] Preparation of polarizing plate 5 Polarization in the same manner as in Example 4 except that epoxy resin 2 (manufactured by Mitsubishi Chemical Corporation, trade name: jER® YX6954BH30) was used instead of epoxy resin 1. Board 5 was obtained.

[Example 6] Preparation of polarizing plate 6 Polarization in the same manner as in Example 4 except that epoxy resin 3 (manufactured by Mitsubishi Chemical Corporation, trade name: jER® YX7200B35) was used instead of epoxy resin 1. A plate 6 was obtained.

[Example 7] Preparation of polarizing plate 7 Polymer (A) -2 was used instead of polymer (A) -1, and a resin for protecting a polarizer so that the thickness after drying was 0.4 μm. A polarizing plate 7 was obtained in the same manner as in Example 4 except that the composition was applied.

[Example 8] Preparation of polarizing plate 8 A resin for protecting a polarizing element is used so that the polymer (A) -3 is used instead of the polymer (A) -1 and the thickness after drying is 0.4 μm. A polarizing plate 8 was obtained in the same manner as in Example 4 except that the composition was applied.

[Example 9] Preparation of polarizing plate 9 A polarizing plate 9 was obtained in the same manner as in Example 7 except that the polarizing element laminate 2 was used instead of the polarizing element laminate 1.

[Example 10] Preparation of polarizing plate 10 The polarizing element laminate 2 was used instead of the polarizing element laminate 1, and the polarizing element protection resin composition was applied so as to have a thickness of 0.7 μm after drying. A polarizing plate 10 was obtained in the same manner as in Example 7 except for the above.

[Example 11] Preparation of polarizing plate 11 A polarizing plate 11 was obtained in the same manner as in Example 1 except that the polymer (A) -4 was used instead of the polymer (A) -1.

[Example 12] Preparation of polarizing plate 12 A polarizing plate 12 was obtained in the same manner as in Example 1 except that the polymer (A) -5 was used instead of the polymer (A) -1.

[Example 13] Preparation of polarizing plate 13 A polarizing plate 13 was obtained in the same manner as in Example 1 except that the polymer (A) -6 was used instead of the polymer (A) -1.

[Example 14] Preparation of polarizing plate 14 A polarizing plate 14 was obtained in the same manner as in Example 1 except that the polymer (A) -7 was used instead of the polymer (A) -1.

[Example 15] Preparation of polarizing plate 15 A polarizing plate 15 was obtained in the same manner as in Example 10 except that the polymer (A) -8 was used instead of the polymer (A) -1.

(Comparative Example 1) Preparation of Polarizing Plate C1 Example 1 except that a resin composition for protecting a polarizer was prepared using 60 parts by weight of the polymer (A) -1 and 40 parts by weight of the epoxy resin 1. The polarizing plate C1 was obtained in the same manner as in the above.

(Comparative Example 2) Preparation of Polarizing Plate C2 Example 1 except that a resin composition for protecting a polarizer was prepared using 40 parts by weight of the polymer (A) -1 and 60 parts by weight of the epoxy resin 1. The polarizing plate C2 was obtained in the same manner as in the above.

(Comparative Example 3) Preparation of Polarizing Plate C3 A polarizing plate C3 was obtained in the same manner as in Example 1 except that 100 parts by weight of the polymer (A) -1 was used as a resin composition for protecting a polarizer.

(Comparative Example 4) Preparation of Polarizing Plate C4 A polarizing plate C4 was obtained in the same manner as in Example 1 except that 100 parts by weight of epoxy resin 1 was used as a resin composition for protecting a polarizer.

(Comparative Example 5) Preparation of Polarizing Plate C5 A polarizing plate C5 was obtained in the same manner as in Example 9 except that 100 parts by weight of the polymer (A) 2 was used as a resin composition for protecting a polarizer.

[Evaluation]
(Preparation of polarizing plate with adhesive layer)
The acrylic pressure-sensitive adhesive composition obtained in Production Example 12 is uniformly coated on the surface of a polyethylene terephthalate film (separator) treated with a silicone-based release agent with a fountain coater, and then air-circulated constant temperature at 155 ° C. It was dried in an oven for 2 minutes to form a 20 μm thick pressure-sensitive adhesive layer on the surface of the separator. Next, this pressure-sensitive adhesive layer was transferred to the surface side of the polarizer protective layer of the polarizing plate obtained in Examples or Comparative Examples to obtain a polarizing plate with a pressure-sensitive adhesive layer. The following evaluation was performed using the obtained polarizing plate with an adhesive layer. The results are shown in Tables 1 and 2.

1. 1. Color loss at the end The above-mentioned polarizing plate with an adhesive layer (protective film / adhesive / polarizer / protective layer / adhesive / separator) was cut out into (50 mm × 50 mm). Then, the separator was peeled off and bonded to non-alkali glass via an adhesive layer. Then, it was left for 72 hours under the conditions of a temperature of 60 degrees and a humidity of 90%. Then, the presence or absence of color loss of the polarizer was confirmed with an optical microscope (manufactured by Olympus, product name: MX61L). The amount of color loss was measured from an image taken with an optical microscope at a magnification of 10 times for the length of color loss from the end of the polarizer. The longest length of the color-missing portion was defined as the length (μm) of the color-missing portion of the polarizer.

2. 2. Anchoring force The above-mentioned polarizing film with an adhesive layer is cut into a size of 25 mm × 150 mm, and the surface of the adhesive layer and the surface of a thin-film vapor-deposited film in which indium-tin oxide is vapor-deposited on the surface of a 50 μm-thick polyethylene terephthalate (PET) film. It was pasted so that they would touch each other. After that, the end of the PET film is peeled off by hand, and after confirming that the adhesive layer is attached to the PET film side, a tensile tester (manufactured by Shimadzu Corporation, product name: AG-1) is used. The stress (N / 25 mm) at the time of peeling at a speed of 300 mm / min in the 180 ° direction was measured (25 ° C.). The anchoring force was measured within 24 hours after the pressure-sensitive adhesive was applied to the polarizing plate and the pressure-sensitive adhesive layer was formed.

3. 3. PVA Adhesion Force For each polarizing plate after measuring the anchoring force, the presence or absence of peeling between the protective layer and the polarizer was visually observed. The case where no peeling was observed between the protective layer and the polarizing element was regarded as OK, and the case where the polarizing element and the protective layer were separated was regarded as NG.

4. Haze rise The polarizing film with the adhesive layer was cut into a size of 50 mm × 50 mm and bonded to glass. The haze value was measured while being attached to glass. The measurement was performed using a haze meter HM150 (manufactured by Murakami Color Technology Research Institute).
Judgment was made based on the following criteria for the increase value of haze with respect to Comparative Example 3 to which no epoxy resin was added.
Best: Increase in haze after coating the protective layer-forming resin composition is less than 1% Good: Increase in haze after coating the protective layer-forming resin composition is 1% or more and less than 3% Possible: Protective layer formation Increase in haze after coating the resin composition cannot be 3% or more and less than 10%: Increase in haze after coating the protective layer forming resin composition is 10% or more.

5. Good judgment: 7N / 25mm or more possible: 5N / 25mm or more and less than 7N / 25mm Impossible: less than 5N / 25mm

The polarizing plates obtained in Examples 1 to 15 were prevented from losing color from the end of the polarizer even when the protective layer was thin. In addition, it has excellent adhesion between the polarizer and the protective layer, enabling protection of the polarizer without peeling, and is compatible with the anchoring force of the adhesive layer formed on the protective layer. It was a thing. Furthermore, the whitening of the protective layer was also well suppressed.

The resin composition for protecting a polarizer of the present invention has excellent adhesion to a polarizer, and even if it is thin, it is possible to provide a polarizing plate in which color loss at an end is prevented. The polarizing plate of the present invention can be widely applied to liquid crystal panels of liquid crystal televisions, liquid crystal displays, mobile phones, digital cameras, video cameras, portable game machines, car navigation systems, copiers, printers, fax machines, watches, microwave ovens, and the like. it can.

10 Polarizer 20 Protective layer 100 Polarizer

Claims (8)

1. (A) A polymer obtained by polymerizing an acrylic monomer having a weight of more than 50 parts by weight and a monomer having a weight of more than 0 parts by weight and less than 50 parts by weight represented by the formula (1).
   (B) A resin composition for protecting a polarizer, which comprises an epoxy resin.
   The resin composition for protecting a polarizer, wherein the content ratios of (A) and (B) are 95: 5 to 60:40 or 40:60 to 1:99 by weight.
   

   

   (In the formula, X is a group consisting of a vinyl group, a (meth) acrylic group, a styryl group, a (meth) acrylamide group, a vinyl ether group, an epoxy group, an oxetane group, a hydroxyl group, an amino group, an aldehyde group, and a carboxyl group. Represents a functional group containing at least one reactive group selected, R ¹ and R ² each independently have a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent, and a substituent. It represents an aryl group which may be used, or a heterocyclic group which may have a substituent, and R ¹ and R ² may be linked to each other to form a ring).
2. The resin composition for protecting a polarizer according to claim 1, wherein the epoxy resin (B) is an epoxy resin having an aromatic ring.
3. The resin composition for protecting a polarizer according to claim 1 or 2, wherein the polymer (A) and the epoxy resin (B) have a weight average molecular weight of 20,000 or more.
4. The resin composition for protecting a polarizer according to any one of claims 1 to 3, wherein the reactive group is at least one selected from the group consisting of a (meth) acrylic group and a (meth) acrylamide group.
5. Polarizer and
   A polarizing plate comprising, on at least one surface of the polarizing element, a protective layer formed from the polarizing element protecting resin composition according to any one of claims 1 to 4.
6. The polarizing plate according to claim 5, wherein the protective layer has a thickness of 0.1 μm to 8 μm.
7. The polarizing plate according to claim 5 or 6, wherein the polarizing element has an iodine content of 2% by weight to 25% by weight.
8. The polarizing plate according to any one of claims 5 to 7, wherein the thickness of the polarizer is 8 μm or less.

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