JP2010277039A - Material for forming polarizer protective film, polarizer protective film, polarizing plate and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a material for forming a polarizer protective film formed of an optically isotropic laminate which is constituted of an acrylic resin layer excelling in durability, such as hydrolysis resistance, and an acrylic adhesive layer excelling in adhesiveness to a polarizer. <P>SOLUTION: In the material for forming the polarizer protective film comprising the acrylic adhesive layer (A) exhibiting a storage modulus G' of 0.01-0.3 MPa at 23°C, prior to being irradiated with active energy rays and having a thickness of 1-30 μm, and the acrylic resin layer (B) having a thickness 10-100 μm, the acrylic adhesive layer (A) is formed of a composition, containing a combination of 5-40 mass% of an active energy ray curable nitrogen-containing heterocyclic compound (a) and 95-60 mass% of a (meth)acrylic acid ester copolymer (b); and the acrylic resin layer (B) is formed of a composition containing 80 mass% or more of copolymer (e), which comprises a methyl methacrylate unit (c) and at least one kind of another (meth)acrylic acid ester unit (d) at a mass ratio of from 60:40 to 99:1 and has weight average molecular weight of 50,000-300,000. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a film forming material for protecting a polarizer, a film for protecting a polarizer, a polarizing plate and a method for producing the same. More specifically, the present invention comprises an optically isotropic laminate having an acrylic resin layer excellent in durability such as hydrolysis resistance and an acrylic pressure-sensitive adhesive layer excellent in adhesion to a polarizer. Material for forming a film for protecting a polarizer, a film for protecting a polarizer having the properties obtained by using the film, a polarizing plate in which a polarizer is sandwiched between the protective film, and an effective polarizing plate It relates to a manufacturing method.

  The liquid crystal display device is a device that modulates incident linearly polarized light with the electro-optical characteristics of the liquid crystal layer and visualizes it as a signal of intensity of transmission or coloring with a polarizing plate on the output side. That is, since polarized light is used for the display principle, the polarizing plate is an essential member. The polarizing plate is an element that converts natural light into linearly polarized light. Currently, many of the polarizing plates that are currently mass-produced and practically used for liquid crystal display devices include a base film made of a polyvinyl alcohol film, iodine and a dichroic dye. A polarizing film obtained by dyeing, adsorbing, and stretching-orienting a dichroic material such as is bonded with a protective film that is optically transparent and has mechanical strength. . The protective film has low birefringence and high optical isotropy, has high light transmittance, excellent heat resistance, excellent mechanical properties, flat surface For example, good adhesion and good adhesion to a polarizer. For this purpose, a cellulose-based film has been conventionally used (see Patent Document 1).

Currently, triacetyl cellulose (hereinafter sometimes referred to as “TAC”) is generally used as the cellulose-based film. However, the TAC film does not have sufficient moisture and heat resistance, and when a polarizing plate using the TAC film as a polarizer protective film is used under high humidity, there is a disadvantage that the performance of the polarizing plate such as the degree of polarization and the hue deteriorates.
Further, the TAC film produces a phase difference with respect to incident light in an oblique direction. Such a phase difference significantly affects viewing angle characteristics as the size of liquid crystal displays increases in recent years.

  As a protective film having good moisture resistance and excellent durability, a polarizing plate is disclosed in which a film obtained by molding an acrylic resin alone or an acrylic resin composition is bonded to both surfaces (see Patent Document 2). . However, an adhesive is used for bonding, and it is necessary to apply immediately before bonding, which is not preferable in terms of productivity, and as an adhesive used when bonding a protective film on both sides, it is optically isotropic. Although there is a description that an excellent material is preferable, only general polyvinyl alcohol-based adhesives, urethane-based adhesives, epoxy-based adhesives, and acrylic-based adhesives are listed.

  Patent Document 3 describes (A) 70 to 95% by mass of a monofunctional (meth) acrylic acid polymer having a weight average molecular weight of 50,000 to 80,000, and (B) a polyfunctional radically polymerizable unsaturated dimer. An optical film obtained by crosslinking and curing an ionizing radiation curable resin composition containing 5 to 30% by mass of a compound having a heavy bond, and a polarizing plate formed by forming this optical film on at least one surface of a polarizer are disclosed. Yes. This optical film has improved flexibility and film transportability, and as an adhesive for bonding to the optical film, a general PVA adhesive, epoxy adhesive, acrylic adhesive They only mention polyolefin adhesives, polyvinyl ether adhesives, and rubber adhesives, and do not define any kind or properties of adhesives.

  Furthermore, as an optical film with a small retardation suitable for polarizer protection applications and a simple manufacturing process, an acrylic film made of a mixed resin of an acrylic polymer containing a ring structure and a polymer containing a styrene polymer is available. It is disclosed (for example, see Patent Document 4). In this technique, the acrylic film is described as having heat resistance, excellent transparency, and almost no birefringence. However, the adhesion between the acrylic film and the polarizer is Not mentioned.

  Even if it is not the TAC film currently used as a protective film used for a polarizing plate, what is excellent in transparency and has optical isotropy should just be sufficient, and many cast films can substitute for it. However, since a polyvinyl alcohol film is generally used as a polarizing film (polarizer), it is difficult to adhere to the film, and it is required to be a low-cost material. In fact, it has not been put to practical use.

JP-A-7-120617 JP 2007-128025 A JP 2008-129212 A JP 2007-197703 A

Currently, when manufacturing a polarizing plate, a PVA-based adhesive is used for bonding the TAC film and the polyvinyl alcohol (PVA) polarizer, and the TAC is used to improve the adhesion to the TAC film. A complicated operation of saponifying the film with alkali is performed.
The present invention has been made under such circumstances, and the first object is excellent adhesion between the acrylic resin layer having excellent durability such as hydrolysis resistance and the PVA polarizer, as described above. A second object of the present invention is to provide a material for forming a polarizer protective film comprising an optically isotropic laminate having an acrylic adhesive layer that does not require any complicated operation. An object of the present invention is to provide a film for protecting a polarizer having the properties obtained by using a material.
A third object is to provide a polarizing plate in which the polarizer protective film is provided on at least one surface of a PVA polarizer.

As a result of intensive studies to achieve the above object, the present inventors have obtained the following knowledge.
By a film forming material for protecting a polarizer having an active energy ray-curable acrylic adhesive layer having a specific thickness, composition and storage modulus, and an acrylic resin layer having a specific thickness, composition and molecular weight, Achieving the first object, and irradiating the film forming material for protecting a polarizer with active energy rays to form a desired film for protecting a polarizer, thereby achieving the second object. I found.
Further, by sandwiching the PVA polarizer with the protective film so that the acrylic adhesive layer after irradiation with the active energy ray in the polarizer protective film is in contact, or the PVA polarizer is A desired polarizing plate is obtained by irradiating active energy rays to those sandwiched between the materials so that the acrylic adhesive layer before irradiation with active energy rays in the child protective film-forming material is in contact therewith. We have found that the objective can be achieved.
The present invention has been completed based on such findings.

That is, the present invention
(1) Acrylic adhesive layer (A) having a thickness of 1 to 30 μm having a storage elastic modulus G ′ at 23 ° C. of 0.01 to 0.3 MPa before irradiation with active energy rays, and an acrylic system having a thickness of 10 to 100 μm. A film forming material for protecting a polarizer having a resin layer (B),
The said acrylic adhesion layer (A) consists of 5-40 mass% of active energy ray hardening-type nitrogen-containing heterocyclic compounds (a), and (meth) acrylic acid ester copolymer (b) 95-60 mass%. The acrylic resin layer (B) is formed from a composition containing a combination, and the mass ratio of the methyl methacrylate unit (c) and at least one other (meth) acrylic acid ester unit (d). A film for protecting a polarizer, comprising a composition containing 80% by mass or more of a copolymer (e) having a weight average molecular weight of 50,000 to 300,000 in a ratio of 60:40 to 99: 1. Forming material,
(2) The film-forming material for protecting a polarizer according to (1) above, wherein the acrylic adhesive layer (A) has a storage elastic modulus G ′ at 23 ° C. after irradiation with an active energy ray of 0.4 to 5 MPa. ,
(3) The film for protecting a polarizer according to (1) or (2) above, wherein the (meth) acrylic acid ester unit (d) in the copolymer (e) has an ethylenic double bond in the side chain. Forming material,
(4) The film-forming material for protecting a polarizer according to the above (3), wherein the content of the unit containing an ethylenic double bond in the copolymer (e) is 0.5 to 20 mol%,
(5) The above (1) to (4), wherein the (meth) acrylic acid ester copolymer (b) in the composition forming the acrylic adhesive layer (A) has an ethylenic double bond in the side chain. The film forming material for protecting a polarizer according to any one of the items,
(6) The film-forming material for protecting a polarizer according to the above (5), wherein the content of the unit containing an ethylenic double bond in the copolymer (b) is 0.5 to 15 mol%,
(7) The film forming material for protecting a polarizer according to any one of (1) to (6) above, wherein a release sheet is affixed to the surface of the acrylic adhesive layer (A),
(8) A film for protecting a polarizer obtained by irradiating an active energy ray to the film-forming material for protecting a polarizer according to any one of (1) to (7) above,
(9) In-plane retardation in the measurement from the acrylic resin layer (B ′) side in the laminate comprising the acrylic adhesive layer (A ′) and the acrylic resin layer (B ′) after irradiation with the active energy ray Is a film for protecting a polarizer according to item (8), wherein the film is 10 nm or less,
(10) The polarizer protective film, such that the acrylic adhesive layer (A ′) of the polarizer protective film according to the above (8) or (9) is in contact with the polarizer on both sides. A polarizing plate characterized by being sandwiched between
(11) The polarizer is made of the above material so that the surfaces on both sides thereof are in contact with the acrylic adhesive layer (A) in the film forming material for protecting a polarizer according to any one of (1) to (7) above. A polarizing plate characterized by irradiating active energy rays to the sandwiched material, and (12) (a) an acrylic adhesive layer (A) and an acrylic resin layer (B) on one side of the process sheet. A step of sequentially laminating, (b) a step of attaching a protective film on the surface of the acrylic resin layer (B), (c) a polarizer on the surface of the acrylic pressure-sensitive adhesive layer (A) that is peeled off and exposed to the surface. A polarizing plate comprising: a step of bonding; and (d) a step of irradiating an active energy ray to a laminate of an acrylic resin layer (B), an acrylic adhesive layer (A), and a polarizer. Manufacturing method,
Is to provide.

Moreover, as a preferable aspect of the film forming material for protecting a polarizer of the present invention,
(A) In the acrylic adhesive layer, the active energy ray is ultraviolet light, and contains a photopolymerization initiator (f), a film forming material for protecting a polarizer,
(B) In the acrylic adhesive layer, a film forming material for protecting a polarizer containing a crosslinking agent (g), preferably an isocyanate crosslinking agent, and (c) a (meth) acrylic acid ester in the copolymer (e) At least a part of the unit (d) contains an alkyl group or alkoxyl group having a branched chain of 3 to 10 carbon atoms as a functional group, and the acrylic resin layer (B) further contains a bisphenol A type phosphate plastic. A film forming material for protecting a polarizer, containing the agent in a proportion of 3 to 20% by mass;
Can be mentioned.

  According to the present invention, a polarizer protection comprising an optically isotropic laminate having an acrylic resin layer having excellent durability such as hydrolysis resistance and an acrylic adhesive layer having excellent adhesion to the polarizer. A material for forming a film, a polarizer protective film having the properties obtained by using the film, a polarizing plate in which the polarizer is sandwiched by the protective film, and an effective method for producing the polarizing plate Can be provided.

It is explanatory drawing which shows the method of evaluating the light leak resistance of the polarizing plate obtained by the Example and the comparative example.

First, the film forming material for protecting a polarizer of the present invention will be described.
[Polarizer protective film forming material]
The polarizer protective film-forming material of the present invention (hereinafter sometimes simply referred to as “protective film-forming material” or “film-forming material”) has a storage elastic modulus G ′ at 23 ° C. before irradiation with active energy rays. A film forming material for protecting a polarizer having an acrylic adhesive layer (A) having a thickness of 0.01 to 0.3 MPa and an acrylic resin layer (B) having a thickness of 10 to 100 μm, The acrylic adhesive layer (A) (hereinafter sometimes referred to as layer (A)) and the acrylic resin layer (B) (hereinafter sometimes referred to as layer (B)) are shown below. It has the characteristics.

(Acrylic adhesive layer (A))
In the film forming material for protecting a polarizer of the present invention, the acrylic adhesive layer used as the layer (A) is sometimes referred to as an active energy ray-curable nitrogen-containing heterocyclic compound (a) (hereinafter referred to as component (a)). .) Is formed from a composition comprising a combination of 5 to 40% by mass and (meth) acrylic acid ester copolymer (b) (hereinafter sometimes referred to as component (b)) 95 to 60% by mass. Layer.
<Active energy ray-curable nitrogen-containing heterocyclic compound (a)>
In the acrylic adhesive layer (A), the active energy rays in the active energy ray-curable nitrogen-containing heterocyclic compound (a) used as an essential component are those having energy quanta in electromagnetic waves or charged particle beams, It refers to ultraviolet rays and electron beams.
The active energy ray-curable nitrogen-containing heterocyclic compound (a) may be monofunctional or polyfunctional, and examples of the monofunctional type include N- (meth) acryloylmorpholine, N- (meta ) Acryloylpiperidine, N- (meth) acryloylpyrrolidine, N- (meth) acryloyloxazolidine, and the like. Examples of the polyfunctional type include tris [(meth) acryloyloxyalkyl] isocyanurate. Preferably include tris (2-acryloyloxyethyl) isocyanurate, tris (3-acryloyloxypropyl) isocyanurate, tris (2-methacryloyloxyethyl) isocyanurate, tris (3-methacryloyloxypropyl) isocyanurate, and the like. be able to. One of these active energy ray-curable nitrogen-containing heterocyclic compounds may be used alone, or two or more thereof may be used in combination.
The “(meth) acryloyl” refers to both acryloyl and methacryloyl. The same applies to other similar terms.
Such an active energy ray-curable nitrogen-containing heterocyclic compound undergoes polymerization of a (meth) acryloyl group upon irradiation with active energy rays, and as a result, the resulting acrylic adhesive layer (A ′) is affixed. While the suitability increases, the nitrogen-containing heterocyclic group improves the adhesion to the PVA polarizer.

<(Meth) acrylic acid ester copolymer (b)>
In the said acrylic adhesive layer (A), there is no restriction | limiting in particular as (meth) acrylic acid ester copolymer (b) used as an essential component, The (meth) acrylic acid conventionally used as a resin component of an adhesive Any one of the ester copolymers can be appropriately selected and used. As such a (meth) acrylic acid ester copolymer, for example, a (meth) acrylic acid alkyl ester having an alkyl group having 4 to 20 carbon atoms, a crosslinking point described later, or an ethylenic double bond is a side chain. Preferred examples include a copolymer of a monomer having a functional group that serves as a reaction point for introduction into the monomer and another monomer used as desired.

  Here, examples of the (meth) acrylic acid alkyl ester having an alkyl group having 4 to 20 carbon atoms include butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, Examples include 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.

On the other hand, examples of the functional group in the monomer having a functional group include —OH, —COOH, —NH ₂ , —NHR (R: a hydrocarbon group having 1 to 10 carbon atoms), —NCO, and an epoxy group. Among these, —OH, —COOH, —NH ₂ , and —NHR having active hydrogen are preferable.
Examples of monomers having such a functional group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 2-hydroxybutyl (meth) acrylate. Hydroxyalkyl (meth) acrylate such as 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 1,6-hexanediol mono (meth) acrylate, monomethylaminoethyl (meth) acrylate, monoethylamino Monoalkylaminoalkyl (meth) acrylates such as ethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate, monoethylaminopropyl (meth) acrylate; N-methylol (meth) acrylamide; acrylic acid, methacrylic acid, crotonic acid, Ma Ynoic acid, itaconic acid, ethylenically unsaturated carboxylic acids such as citraconic acid. These monomers may be used independently and may be used in combination of 2 or more type.

  Examples of other monomers used as desired include (meth) acrylic acid having an alkyl group having 1 to 3 carbon atoms such as methyl (meth) acrylate, ethyl (meth) acrylate, and propyl (meth) acrylate. Esters; vinyl esters such as vinyl acetate and vinyl propionate; olefins such as ethylene, propylene and isobutylene; halogenated olefins such as vinyl chloride and vinylidene chloride; styrene monomers such as styrene and α-methylstyrene; Diene monomers such as butadiene, isoprene and chloroprene; Nitrile monomers such as acrylonitrile and methacrylonitrile; (meth) acrylamide, N-methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, etc. Examples include (meth) acrylamides. These may be used alone or in combination of two or more. From the viewpoint of imparting adhesive strength to the resulting adhesive layer, the (meth) acrylic acid ester copolymer (b) has an alkyl group having 4 to 20 carbon atoms in an amount of 50% by mass or more of the constituent monomers. It is preferable to consist of the (meth) acrylic-acid alkylester which has, and it is especially preferable that it is 60-99 mass%.

The (meth) acrylic acid ester copolymer (b) is not particularly limited as to its copolymerization form, and may be any of random, block, and graft copolymers. In addition, the molecular weight is preferably 500,000 or more, more preferably 500,000 to 2,500,000 in terms of weight average molecular weight. If the weight average molecular weight is less than 500,000, the adhesion to the adherend and the durable adhesion may be insufficient. In view of adhesiveness, durable adhesiveness, etc., the weight average molecular weight is preferably 700,000 to 2,000,000.
In addition, the said weight average molecular weight is the value of standard polystyrene conversion measured by the gel permeation chromatography (GPC) method.

Further, in the (meth) acrylic acid ester copolymer (b), the content of the monomer unit having the functional group is preferably in the range of 0.5 to 20% by mass. If the content is less than 0.5% by mass, the number of crosslinking points is too small, crosslinking is insufficient, and the cohesive failure of the pressure-sensitive adhesive layer may occur. If the content exceeds 20% by mass, suitability for application to a PVA polarizer is likely. There is a risk of decline. The more preferable content of the monomer unit having this functional group is 1 to 15% by mass, and the range of 2 to 10% by mass is particularly preferable. Furthermore, as a monomer having a functional group preferable for achieving the object of the present invention, 2-hydroxyethyl (meth) acrylate is particularly preferable from the viewpoint of adhesiveness with a PVA polarizer, and adhesion of a PVA polarizer is preferred. In view of the shortening of the seasoning period in addition to the properties, (meth) acrylic acid is particularly preferable.
2-hydroxyethyl (meth) acrylate has a monomer unit content in the (meth) acrylic acid ester copolymer of 0.5 to 0.5 from the viewpoint of not deteriorating other properties such as durability while exhibiting the above properties. The range is preferably 20% by mass, more preferably 1 to 10% by mass, and particularly preferably 2 to 5% by mass.
On the other hand, the (meth) acrylic acid has a monomer unit content of 0.5 to 20 in the (meth) acrylic acid ester copolymer from the viewpoint of not deteriorating other properties such as durability while exhibiting the above properties. The range of mass% is preferable, the range of 1 to 15 mass% is more preferable, and the range of 5 to 10 mass% is particularly preferable.
In consideration of easy design of the pressure-sensitive adhesive layer, the 2-hydroxyethyl (meth) acrylate and the (meth) acrylic acid are contained in the same (meth) acrylic acid ester copolymer (b). It is preferable to incorporate and blend in a separate (meth) acrylic acid ester copolymer (b) rather than being incorporated into the copolymer. (Meth) acrylic acid ester copolymer (b-1) containing 2-hydroxyethyl (meth) acrylate as a monomer unit as a monomer having a functional group and (meth) as a monomer having a functional group The mixing ratio of the (meth) acrylic acid ester copolymer (b-2) containing acrylic acid as a monomer unit is preferably 50:50 to 95: 5 by mass ratio, and 60:40 to 90:10 is more preferable, and 70:30 to 80:20 is particularly preferable.

In the present invention, this (meth) acrylic acid ester copolymer (b) can introduce an ethylenic double bond into the side chain as desired. In this case, a compound having an ethylenic double bond to be reacted with the functional group is selected according to the type of the functional group located in the side chain of the monomer unit having the functional group. For example, when the functional group is a functional group having active hydrogen, specifically —OH, —COOH, —NH ₂ , —NHR (R is the same as above), the ethylenic double group to be reacted with the functional group As the compound having a bond, 2- (meth) acryloyloxyethyl isocyanate, 3- (meth) acryloyloxypropyl isocyanate and the like are preferably used.
In this way, the (meth) acrylic ester copolymer (b) in which the (meth) acryloyloxyalkyl group is introduced as a unit containing an ethylenic double bond in the side chain, Adhesiveness at the interface is improved, storage elastic modulus is increased, and durability is improved.
The content of the unit containing an ethylenic double bond in this (meth) acrylic acid ester copolymer (b) is 0.5 to 15 mol from the viewpoint of the balance between the adhesiveness and the durable adhesion at the adhesive layer interface. %, And more preferably 1 to 10 mol%.
In addition, as described above, when the (meth) acrylic acid ester copolymer (b-1) and the (b-2) are blended and used, the (meth) acrylic acid ester copolymer (b) In the case of being composed of multiple components, the content of the unit containing the ethylenic double bond determines the aforementioned blending ratio by the sum of the respective components. For example, in the case of a mixed system of (meth) acrylic acid ester copolymer (b-1) and (b-2), the content of units containing ethylenic double bonds among all the monomers constituting these is 0.5 to 15 mol% is preferable, and 1 to 10 mol% is more preferable.

In the present invention, as the component (b), one kind of this (meth) acrylic acid ester copolymer may be used as in the case where the components (b-1) and (b-2) are used in combination. And two or more kinds may be used in combination. In the case of combining a plurality of types, a combination of those having no ethylenic double bond in the side chain and those having a side chain may be used, or combinations of those having or not having each other.
The acrylic pressure-sensitive adhesive layer (A) comprises the aforementioned active energy ray-curable nitrogen-containing heterocyclic compound (a) 5 to 40% by mass, (meth) acrylic acid ester copolymer (b) 95 to 60% by mass, When the content of the component (a) is out of the above range, the acrylic pressure-sensitive adhesive layer (A ′) obtained by irradiation with active energy rays has a sticking suitability and a layer formed from a composition comprising a combination of The adhesion to the PVA polarizer cannot be improved. A preferable content rate is 5 to 30% by mass of the component (a) and 95 to 70% by mass of the component (b), and a more preferable content rate is 10 to 20% by mass of the component (a). b) is 90 to 80% by mass.

<Properties of acrylic adhesive layer (A)>
The acrylic adhesive layer (A) has a thickness of 1 to 30 μm and a storage elastic modulus G ′ at 23 ° C. in the range of 0.01 to 0.3 MPa. When the thickness is less than 1 μm, the acrylic pressure-sensitive adhesive layer (A ′) obtained by irradiation with active energy rays cannot sufficiently function as the pressure-sensitive adhesive layer, while it is thicker than 30 μm from the viewpoint of adhesiveness. It is not necessary, but rather, increasing the thickness causes inconveniences such as the adhesive sticking out. A preferable thickness is 2 to 25 μm, and a more preferable thickness is 3 to 10 μm.
The storage elastic modulus at 23 ° C. is preferably 0.02 to 0.25 MPa, more preferably 0.05 to 0.2 MPa from the viewpoint of bonding suitability.
Furthermore, the acrylic adhesive layer (A) has a storage elastic modulus G ′ at 23 ° C. after irradiation with active energy rays, that is, the acrylic adhesive layer (A ′), in view of adherability and durability adhesion to a PVA polarizer. Therefore, it is preferably 0.4 to 5 MPa, more preferably 0.5 to 3 MPa, and still more preferably 0.7 to 2 MPa.
The storage elastic modulus (G ′) is a value measured by the following method.
<Method for measuring storage elastic modulus (G ′)>
An acrylic adhesive layer (A) is formed on the release layer surface side of the release sheet. Next, the release sheet is removed, the acrylic pressure-sensitive adhesive layer (A) is laminated to a thickness of 3 mm, and a test piece of the acrylic pressure-sensitive adhesive layer (A) is produced by punching out into a cylindrical shape of 8 mmφ. Moreover, the test piece of an acrylic adhesive layer (A ') is produced by irradiating the said test piece with the predetermined active energy ray mentioned later. The storage elastic modulus (G ′) of the acrylic pressure-sensitive adhesive layer (A) or the acrylic pressure-sensitive adhesive layer (A ′) is measured by the torsional shear method according to JIS K 7244-6 for each of the above-mentioned test pieces. It is measured under the conditions of 1 Hz and temperature: 23 ° C.

<Photopolymerization initiator>
In the present invention, ultraviolet rays are preferred as the active energy ray, and therefore the photopolymerization initiator (f) can be contained in the acrylic adhesive layer (A). Examples of the photopolymerization initiator (f) include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, and 2,2-dimethoxy-2- Phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) Phenyl] -2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2 (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4′-diethylaminobenzoph Non, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2 1, 4-diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoate, and the like.
These may be used alone or in combination of two or more, and the blending amount is usually 0.2 to 10 parts by mass with respect to 100 parts by mass of the total active energy ray-curable compound. Is selected within the range.
The total active energy ray-curable compound is an active energy ray-curable nitrogen-containing heterocyclic compound when an ethylenic double bond is introduced into the side chain of the (meth) acrylate copolymer (b). The sum of the mass of (a) and the mass of the unit containing the ethylenic double bond is indicated.

<Crosslinking agent>
The acrylic pressure-sensitive adhesive layer (A) can contain a crosslinking agent (g). There is no restriction | limiting in particular as a crosslinking agent (g), Arbitrary things can be suitably selected and used from what was conventionally used as a crosslinking agent in acrylic resin. Examples of such crosslinking agents include polyisocyanate compounds, epoxy resins, melamine resins, urea resins, dialdehydes, methylol polymers, aziridine compounds, metal chelate compounds, metal alkoxides, metal salts, and the like. Isocyanate compounds are preferably used.
Examples of polyisocyanate compounds include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, and isophorone diisocyanate. Nalto, cycloaliphatic polyisocyanates such as hydrogenated diphenylmethane diisocyanate, etc., and their biurets, isocyanurates, and low molecular weights such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, castor oil Examples thereof include adducts (for example, trimethylolpropane-modified tolylene diisocyanate) that are a reaction product with an active hydrogen-containing compound.
In this invention, this crosslinking agent (g) may be used individually by 1 type, and may be used in combination of 2 or more type. The amount used depends on the type of the crosslinking agent, but is usually 0.01 to 20 parts by mass, preferably 0.1 to 100 parts by mass of the (meth) acrylic acid ester copolymer (b). It is selected in the range of -10 parts by mass.

<Preparation of Acrylic Adhesive Layer (A) Forming Coating Liquid>
In this invention, the coating liquid (composition) for forming the said acrylic adhesion layer (A) is prepared.
There is no particular limitation on the method for preparing the coating liquid, and for example, in the solvent, the aforementioned active energy ray-curable nitrogen-containing heterocyclic compound (a) and the (meth) acrylic acid ester copolymer (b) And a photopolymerization initiator of component (f) and / or a crosslinking agent of component (g) used as necessary, and various additives such as an antioxidant, an ultraviolet absorber, a light stabilizer, and an antistatic agent. A coating liquid for forming an acrylic adhesive layer (A) can be prepared by adding a leveling agent, an antifoaming agent, and the like and stirring and mixing.
Examples of the solvent include aliphatic hydrocarbons such as hexane and heptane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and ethylene chloride, alcohols such as methanol, ethanol, propanol, and butanol, acetone. , Ketones such as methyl ethyl ketone, 2-pentanone, isophorone and cyclohexanone, esters such as ethyl acetate and butyl acetate, cellosolv solvents such as ethyl cellosolve, glycol ether solvents such as propylene glycol monomethyl ether, and the like. These solvents may be used alone or in a combination of two or more.
The concentration of the coating solution is not particularly limited as long as it is a viscosity suitable for coating.

(Acrylic resin layer (B))
In the film forming material for protecting a polarizer of the present invention, the acrylic resin layer used as the layer (B) is composed of a methyl methacrylate unit (c) and at least one other (meth) acrylate unit (d). Is a layer formed from a composition containing 80% by mass or more of a copolymer (e) having a weight average molecular weight of 50,000 to 300,000 in a mass ratio of 60:40 to 99: 1.
<Copolymer (e)>
The (meth) acrylic acid ester unit (d) in the copolymer (e) is a unit introduced for imparting flexibility, refractive index control and a reactive group to the copolymer (e). As the (meth) acrylic acid ester forming the unit, for example, an acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms and a methacrylic acid alkyl ester having 2 to 20 carbon atoms in the alkyl group are used. Mention may be made of at least one (meth) acrylic acid ester selected from among them. Specifically, methyl acrylate, ethyl (meth) acrylate, various propyl (meth) acrylates, various butyl (meth) acrylates, various pentyl (meth) acrylates, various hexyl (meth) acrylates, cyclohexyl (meth) acrylates, 2-ethylhexyl Examples include (meth) acrylate, isooctyl (meth) acrylate, various decyl (meth) acrylates, various dodecyl (meth) acrylates, various tetradecyl (meth) acrylates, various hexadecyl (meth) acrylates, and various octadecyl (meth) acrylates.
In addition, various alkyl (meth) acrylates mean that the alkyl group of the ester moiety includes each isomer.
In the present invention, from the viewpoint of durability and flexibility, at least a part of the (meth) acrylic acid ester is an alkyl group having a branched chain having 3 to 10 carbon atoms or an alkoxyl group as a functional group. Those which are (meth) acrylic acid esters having an alkyl group contained as are preferred, and those in which the (meth) acrylic acid ester is t-butyl methacrylate are particularly preferred.

In the present invention, the (meth) acrylic acid ester unit (d) in the copolymer (e) can introduce an ethylenic double bond into the side chain. In this case, if a monomer unit having a functional group serving as a reaction point is introduced into the (meth) acrylic acid ester unit (d) and a compound having an ethylenic double bond is reacted with this functional group. Good. The functional group is preferably a functional group having active hydrogen, such as —OH, —COOH, —NH ₂ , —NHR (R: a hydrocarbon group having 1 to 10 carbon atoms). The (meth) acrylate monomer for introducing these functional groups is as described in the description of the (meth) acrylate copolymer (b) in the acrylate-based adhesive layer (A).
As the compound having an ethylenic double bond to be reacted with the functional group, 2- (meth) acryloyloxyethyl isocyanate, 3- (meth) acryloyloxypropyl isocyanate and the like are preferably used.
The (meth) acryloyl ester unit (d) in which the (meth) acryloyloxyalkyl group is introduced as a unit containing an ethylenic double bond in the side chain in this way is irradiated with active energy rays. Polymerization of the (meth) acryloyl group occurs, and as a result, the resulting acrylic resin layer (B ′) has improved mechanical properties, improved adhesion to the adhesive layer interface, and improved durability after polarizer bonding. To do.
The content of the unit containing an ethylenic double bond in the (meth) acrylic acid ester unit (d) is 0.5 to 0.5 per all monomer units constituting the copolymer (e) from the viewpoint of interfacial adhesion. It is preferably 20 mol%, more preferably 1 to 10 mol%.

In the acrylic resin layer (B), the copolymer (e) comprises a methyl methacrylate unit (c) and a (meth) acrylic ester unit (d) in a mass ratio of 60:40 to 99: 1. It needs to be included in proportion. When the content of the (meth) acrylic acid ester unit (d) in the copolymer (e) is less than 1% by mass, the acrylic resin layer (B) has insufficient flexibility, while 40% by mass is reduced. When it exceeds, the mechanical characteristic of the said acrylic resin layer (B) will fall.
A preferable content ratio of the methyl methacrylate unit (c) and the (meth) acrylic acid ester unit (d) is a mass ratio of 60:40 to 95: 5, and a more preferable content ratio is a mass ratio of 70:30 to 90. : 10.
The weight average molecular weight of the copolymer (e) is in the range of 50,000 to 300,000. When the weight average molecular weight is less than 50,000, the strength of the layer (B) may be reduced. On the other hand, when the weight average molecular weight is more than 300,000, the viscosity of the coating liquid for forming the layer (B) becomes too high and workability is lowered. There is a case. A preferable weight average molecular weight is 50,000 to 200,000, and a more preferable weight average molecular weight is 70,000 to 150,000.
The said weight average molecular weight is a value of standard polystyrene conversion measured by a gel permeation chromatography (GPC) method.

The acrylic resin layer (B) can contain other components as desired in a proportion of 20% by mass or less in addition to the copolymer (e).
<Active energy ray-curable monomer and / or prepolymer>
The acrylic resin layer (B) may contain an active energy ray-curable monomer and / or prepolymer at a ratio of 20% by mass or less, as necessary, within a range where the effects of the present invention are not impaired. Can do.

As the active energy ray-curable monomer, a polyfunctional (meth) acrylate monomer can be used.
Examples of this polyfunctional (meth) acrylate monomer include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and polyethylene glycol diester. (Meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) acrylate, ethylene oxide modified di (meth) acrylate phosphoric acid, allylation Cyclohexyl di (meth) acrylate, isocyanurate di (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid modified dipentaerythritol tri (meth) acrylate Pentaerythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris (acryloxyethyl) isocyanurate, propionic acid modified dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, Examples thereof include polyfunctional (meth) acrylates such as caprolactone-modified dipentaerythritol hexa (meth) acrylate. These monomers may be used alone or in combination of two or more.

On the other hand, as the active energy ray curable prepolymer, a (meth) acrylate-based prepolymer can be used. Examples of the (meth) acrylate prepolymer include polyester acrylate, epoxy acrylate, urethane acrylate, polyol acrylate, and the like. Here, as the polyester acrylate-based prepolymer, for example, by esterifying the hydroxyl group of a polyester oligomer having a hydroxyl group at both ends obtained by condensation of a polyvalent carboxylic acid and a polyhydric alcohol with (meth) acrylic acid, or It can be obtained by esterifying the terminal hydroxyl group of an oligomer obtained by adding an alkylene oxide to a polyvalent carboxylic acid with (meth) acrylic acid.
The epoxy acrylate prepolymer can be obtained, for example, by reacting (meth) acrylic acid with an oxirane ring of a relatively low molecular weight bisphenol type epoxy resin or novolak type epoxy resin and esterifying it. The urethane acrylate-based prepolymer can be obtained, for example, by esterifying a polyurethane oligomer obtained by reaction of polyether polyol or polyester polyol and polyisocyanate with (meth) acrylic acid. Furthermore, the polyol acrylate-based prepolymer can be obtained by esterifying the hydroxyl group of the polyether polyol with (meth) acrylic acid. These prepolymers may be used singly or in combination of two or more, or may be used in combination with the polyfunctional (meth) acrylate monomer.

In the acrylic resin layer (B), as described above, the (meth) acrylic acid ester unit (d) in the copolymer (e) has an ethylenic double bond in the side chain, or active energy. In the case of containing a line curable monomer and / or prepolymer, irradiation with active energy rays causes the polymerization reaction of the ethylenic double bond and the active energy ray curable monomer and / or prepolymer, resulting in a three-dimensional Thus, the acrylic resin layer (B) can be provided with scratch resistance, heat resistance, and moist heat resistance. In this case, the active energy ray is preferably ultraviolet rays, and therefore a photopolymerization initiator can be used in combination as necessary. As this photoinitiator, the same thing as the photoinitiator (f) shown in description of the above-mentioned acrylic adhesion layer (A) can be mentioned.
The compounding quantity of this photoinitiator is normally chosen in the range of 0.2-10 mass parts with respect to 100 mass parts of all active energy ray hardening-type compounds. The total active energy ray-curable compound is an active energy ray-curable monomer and / or prepolymer when an ethylenic double bond is introduced into the side chain of the (meth) acrylate unit (d). It refers to the sum of the mass and the mass of the unit containing the ethylenic double bond.

<Plasticizer>
The acrylic resin layer (B) can contain a plasticizer as desired for the purpose of imparting flexibility and the like. Although there is no restriction | limiting in particular as this plasticizer, The bisphenol A type | mold phosphate plasticizer is preferable, For example, the diphenoxy phosphoric acid ester of bisphenol A etc. can be used.
The content of the plasticizer in the acrylic resin layer (B) is preferably 3 to 20% by mass, more preferably 5 to 15% by mass.

The thickness of the acrylic resin layer (B) is selected in the range of 10 to 100 μm. If this thickness is in the above range, the function as a protective film is sufficiently exhibited. The thickness is preferably 10 to 80 μm, more preferably 20 to 50 μm.
In the present invention, a coating liquid (composition) for forming the acrylic resin layer (B) is prepared.

<Preparation of coating liquid for forming acrylic resin layer (B)>
There is no particular limitation on the method for preparing the coating liquid. For example, the above-described copolymer (e), an active energy ray-curable monomer and / or prepolymer, and a photopolymerization initiator used as necessary in a solvent. Acrylic resin layer (B) by adding a plasticizer, and further various additives such as an antioxidant, an ultraviolet absorber, a light stabilizer, an antistatic agent, a leveling agent, an antifoaming agent, and the like, followed by stirring and mixing. A forming coating solution can be prepared.
Examples of the solvent include aliphatic hydrocarbons such as hexane and heptane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and ethylene chloride, alcohols such as methanol, ethanol, propanol, and butanol, acetone. , Ketones such as methyl ethyl ketone, 2-pentanone, isophorone and cyclohexanone, esters such as ethyl acetate and butyl acetate, cellosolv solvents such as ethyl cellosolve, glycol ether solvents such as propylene glycol monomethyl ether, and the like. These solvents may be used alone or in a combination of two or more.
The concentration of the coating solution is not particularly limited as long as it is a viscosity suitable for coating.

(Manufacture of film forming material for protecting polarizer)
The film forming material for protecting a polarizer of the present invention has a laminated structure composed of the acrylic adhesive layer (A) and the acrylic resin layer (B) described above, and on the acrylic adhesive layer (A) surface, A release sheet may be affixed.
Examples of the release sheet include papers such as glassine paper, coated paper, and laminated paper, and various plastic films coated with a release agent such as a silicone resin. Although there is no restriction | limiting in particular about the thickness of this peeling sheet, Usually, it is about 20-150 micrometers.
When manufacturing such a protective film-forming material with a release sheet, the following method can be used.
From the release sheet side, an acrylic adhesive layer (A) having a dry film thickness of 1 to 30 μm and an acrylic resin layer (B) having a dry film thickness of 10 to 100 μm are sequentially formed on the release layer side of the release sheet. The formation of the layer (A) and the layer (B) is performed using the above-described coating solution for forming the layer (A) and the coating solution for forming the layer (B), respectively. Although there is no restriction | limiting in particular in the coating method, From the viewpoint of productivity, the method of using a two-layer die is preferable. A protective film may be attached to the surface of the acrylic resin layer (B) of the two-layer laminate thus obtained. As the protective film, a polyethylene terephthalate film having a thickness of about 25 to 100 μm and subjected to a peeling treatment or untreated is usually used.
Thus, the film forming material for protecting a polarizer of the present invention can be produced.

Next, the polarizer protective film of the present invention will be described.
[Polarizer protective film]
The polarizer protective film of the present invention comprises an acrylic adhesive layer (A ′) obtained by irradiating the above-described polarizer protective film-forming material of the present invention with active energy rays, and an acrylic resin layer (B ').
As described above, the active energy rays are preferably ultraviolet rays. For example, a polarizer protective film can be produced as follows.
The protective film forming material composed of the layer (A) and the layer (B) sandwiched between the release sheet and the protective film obtained as described above is irradiated with ultraviolet rays from the protective film side or the release sheet side. In this case, the protective film or release sheet needs to have ultraviolet transparency.
Further, ultraviolet rays, a high-pressure mercury lamp, electrodeless lamp, obtained with a xenon lamp, the illuminance 100~500mW / cm ² or so, the amount of light is approximately 150~500mJ / cm ^2.
In the film for protecting a polarizer of the present invention having a two-layer laminated structure composed of the acrylic pressure-sensitive adhesive layer (A ′) and the acrylic resin layer (B ′) thus obtained, the acrylic resin layer (B ') The in-plane retardation in the measurement from the side can be 10 nm or less, preferably 5 nm or less.
In the polarizer protective film of the present invention, for example, as described above, a two-layer laminate comprising an acrylic adhesive layer (A ′) and an acrylic resin layer (B ′) is sandwiched between a release sheet and a protective film. The release sheet is peeled off, and the exposed acrylic adhesive layer (A ′) is bonded so as to be in contact with at least one surface of the polarizer, thereby exhibiting a function as a protective film for the polarizer. .

Next, the polarizing plate of the present invention will be described.
[Polarizer]
The polarizing plate of the present invention includes the following two types of polarizing plate I and polarizing plate II.
(Polarizing plate I)
The polarizing plate I of the present invention is narrowed with the above polarizer protective film so that the polarizer is in contact with the acrylic adhesive layer (A ′) in the above-described polarizer protective film of the present invention. It is characterized by having.

<Polarizer>
The polarizer used for this invention should just be normally used, and is not restrict | limited in particular. For example, preferred is a film obtained by adsorbing iodine, a dichroic dye or the like on a hydrophilic polymer film and stretching and aligning it. As a specific example, a polarizer is obtained by dyeing and adsorbing iodine or a dichroic dye on a polyvinyl alcohol film, uniaxially stretching in an aqueous boric acid solution, and washing and drying while maintaining the stretched state. be able to. The draw ratio of uniaxial stretching is usually about 4 to 8 times. Commercially available products such as “Kuraray Vinylon” [manufactured by Kuraray Co., Ltd.], “Tosero Vinylon” [manufactured by Tosero Co., Ltd.], “Nichigo Vinylon” [manufactured by Nippon Synthetic Chemical Co., Ltd.] Can be used.

(Polarizing plate II)
In the polarizing plate II of the present invention, the polarizer is sandwiched between the above materials so that the acrylic adhesive layer (A) in the above-described polarizer protective film-forming material of the present invention is in contact with the polarizer on both sides. It is characterized by being irradiated with active energy rays.
The polarizing plate II can be produced as follows using a protective film-forming material composed of a layer (A) and a layer (B) sandwiched between, for example, the release sheet and the protective film described above. .
The release sheet of the protective film-forming material is peeled off, and the exposed layer (A) is bonded so as to be in contact with the polarizer, and then the active energy ray, preferably ultraviolet rays are irradiated from the protective film side.
Next, on the surface where the polarizer layer (A) is not bonded, the release sheet is similarly peeled off and bonded so that the layer (A) is in contact. Preferably, it is composed of acrylic resin layer (B ′) / acrylic adhesive layer (A ′) / polarizer / acrylic adhesive layer (A ′) / acrylic resin layer (B ′) by irradiating with ultraviolet rays. The polarizing plate II is obtained.
This polarizer is as having demonstrated in the said polarizing plate I, About an ultraviolet-ray, illumination intensity, and a light quantity, it is as having demonstrated in the film for polarizer protection of this invention.

The present invention also provides a method for producing a polarizing plate.
The manufacturing method of the polarizing plate of the present invention includes (a) a step of sequentially laminating an acrylic adhesive layer (A) and an acrylic resin layer (B) on one side of a process sheet, and (b) the acrylic resin layer (B ) A step of attaching a protective film on the surface, (c) a step of peeling the process sheet and attaching a polarizer to the exposed acrylic adhesive layer (A) surface, and (d) an acrylic resin layer (B ), An acrylic adhesive layer and a polarizer, and a step of irradiating active energy rays to the laminate.
In the step (a), as the process sheet, a release sheet can be used as described in the production of the polarizer protective film-forming material.
The steps (a) and (b) are as described in the production of the polarizer protective film-forming material. Further, the steps (c) and (d) are as described in the description of the polarizing plate II described above.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
Various characteristics in each example were determined as follows.
(1) Storage elastic modulus at 23 ° C. of acrylic pressure-sensitive adhesive layer (A) before irradiation with active energy rays and acrylic pressure-sensitive adhesive layer (A ′) after irradiation Peeled sheet [trade name “SP-PET381031 manufactured by Lintec Corporation] The acrylic pressure-sensitive adhesive layer is formed by applying and drying the acrylic pressure-sensitive adhesive layer (A) forming coating liquid of Example or Comparative Example so that the film thickness after drying is 25 μm on the release layer of “]”. . Next, the release sheet is removed, the acrylic pressure-sensitive adhesive layer (A) is laminated to a thickness of 3 mm, and punched into a cylindrical shape of 8 mmφ to prepare a test piece of the acrylic pressure-sensitive adhesive layer. Moreover, the test piece of an acrylic adhesion layer (A ') is produced by irradiating the said test piece with an ultraviolet-ray (light quantity: 300mJ / cm < ² >).
The storage elastic modulus (G ′) of each of the acrylic adhesive layer (before irradiation) or the acrylic adhesive layer (after irradiation) is determined by the torsional shear method according to JIS K 7244-6 for each of the test pieces. It is a value measured under conditions of a frequency of 1 Hz and a temperature of 23 ° C. using an elastic measuring device [manufactured by Rheometrics (currently TA Instruments), device name “DYNAMIC ANALYZER RDAII”].
(2) Weight average molecular weight Mw of the polymer
It measured on the following conditions using gel permeation chromatography (GPC), and calculated | required the weight average molecular weight Mw in polystyrene conversion.
(Measurement condition)
GPC measuring device: “HLC-8020” manufactured by Tosoh Corporation
GPC column (passed in the following order): TSK guard column HXL-H manufactured by Tosoh Corporation
TSK gel GMHXL (× 2)
TSK gel G2000HXL
Measuring solvent: Tetrahydrofuran Measuring temperature: 40 ° C

(3) Retardation in the in-plane direction of the polarizer protective film Irradiate ultraviolet rays (light amount: 300 mJ / cm ² ) from the acrylic resin layer (B) side of the polarizer protective film-forming material produced in the examples and comparative examples. Thus, a polarizer protective film was produced. The polarizer protective film is peeled off the release sheet, and the retardation in the in-plane direction is measured from the acrylic resin layer (B ′) side using a phase difference measuring device [manufactured by Oji Scientific Instruments, model “KOBRA-WR”]. did.
(4) Adhesiveness between polarizer and acrylic adhesive layer (A ′) Acrylic adhesion between the polarizer prepared in Example 1 described later and a TAC film [manufactured by Fuji Film Co., Ltd., trade name “TD80UL”] Bonding was performed using an agent [manufactured by Sumitomo 3M, "DP-8005 clear"]. The other side of the TAC film was bonded to 8 inch glass using the acrylic adhesive [manufactured by Sumitomo 3M, "DP-8005 clear"]. Then, the acrylic adhesive layer (A) of the film forming material for protecting a polarizer prepared in Examples and Comparative Examples is bonded to the surface of the exposed polarizer and irradiated with ultraviolet rays (light quantity: 300 mJ / cm ² ). Thus, an adhesion evaluation sample in which a polarizer protective film was laminated on a polarizer was produced. In addition, the adhesion evaluation sample was laminated | stacked so that the edge part of the film for polarizer protection might protrude 50 mm or more from 8-inch glass.
The obtained sample fixed 8 inch glass, and visually evaluated the state of the interface when the edge part of the polarizer protective film was sandwiched and peeled off with pliers according to the following criteria.
○: The polarizer was agglomerated and destroyed Δ: Although the surface of the polarizer was rough in some places, it was peeled off at the interface with the layer (A ′) ×: It was peeled off cleanly at the interface between the polarizer and the layer (A ′) ( 5) Adhesiveness of acrylic adhesive layer (A ′) and acrylic resin layer (B ′) Two film forming materials for protecting a polarizer in Examples and Comparative Examples were prepared. The polarizer protective film-forming material was prepared by scraping the acrylic adhesive layer (A) with a cutter knife so that the end of the acrylic resin layer protruded from the acrylic adhesive layer (A) by 50 mm or more.
The same sample of the polarizer protective film-forming material is bonded so that the acrylic adhesive layer is in contact with each other, and irradiated with ultraviolet rays (light quantity: 300 mJ / cm ² ), the acrylic adhesive layer (A ′) and the acrylic resin A sample for evaluating the adhesion of the layer (B ′) was prepared.
The adhesion evaluation sample is evaluated by the following criteria by observing the state of the interface between the acrylic pressure-sensitive adhesive layer (A) and the acrylic resin layer (B) by sandwiching and peeling the protruding both ends with pliers. did.
A: Cohesive failure occurred in a state where the interface between the layer (A ′) and the layer (B ′) was not known at all. ○: Peeling occurred at the interface between the layer (A ′) and the layer (B ′). X: Peeled at the interface between layer (A ′) and layer (B ′) without cohesive failure (6) Durability and light leakage resistance of polarizing plate Examples 1-4 and Comparative Example 1 were polarizing plates A pressure sensitive adhesive [trade name “P-0280” manufactured by LINTEC Co., Ltd.] is applied to one side of the substrate to a thickness of 20 μm, and is applied to an 8-inch glass plate, and is put into an endurance test under the conditions shown in Table 1. Then, the light leakage resistance was evaluated by the following method, and the appearance change was visually observed.
<Evaluation of light leakage resistance>
A polarizing plate with an adhesive was bonded to the front and back of an 8-inch glass plate so that the polarization axis was in a crossed Nicol state, and after putting it into an endurance test, the light leakage resistance was evaluated by the method shown below.
Using “MCPD-2000” manufactured by Otsuka Electronics Co., Ltd., the brightness of each region shown in FIG. 1 is measured, and the brightness difference ΔL ^* is expressed by the formula ΔL ^* = [(b + c + d + e) / 4] −a
(Where a, b, c, d, and e are the lightness values at predetermined measurement points (one central portion of each region) in the A region, B region, C region, D region, and E region, respectively. ) To obtain light leakage resistance. The higher the value of ΔL ^* is small, indicating that the light leakage is small.
<Durability evaluation>
After the durability test described in Table 1, the appearance change was visually observed, and the durability was evaluated according to the following criteria.
1: No change in appearance 2: Slight color change, wrinkles, floats, foaming is observed 3: Obvious changes in appearance are observed

Example 1
(1) Preparation of coating liquid for forming acrylic adhesive layer (A) Copolymer of butyl acrylate: 2-hydroxyethyl acrylate mass ratio = 98: 2 (weight average molecular weight Mw: 1,500,000, solid content concentration: 15 mass% ) 80 parts by mass and 20 parts by mass of a copolymer solution of butyl acrylate: acrylic acid mass ratio = 90: 10 (weight average molecular weight Mw: 1,500,000, solid content concentration: 15% by mass) with UV curable polyfunctional acrylate A certain tris (acryloxyethyl) isocyanurate [manufactured by Toa Gosei Co., Ltd., trade name “Aronix M-315”, molecular weight 578, solid content concentration 100%] 3.5 parts by mass was mixed. Furthermore, 0.17 parts by mass of a 1: 1 mixture of benzophenone and 1-hydroxycyclohexyl phenyl ketone (product name “Irgacure 500”, trade name “Irgacure 500”) of isocyanate as a photopolymerization initiator and isocyanate-based crosslinking Trimethylolpropane-modified tolylene diisocyanate (trade name “Coronate L”, solid content concentration: 75% by mass) made by Nippon Polyurethane Co., Ltd., which is an agent, is added and mixed to obtain a layer (A) A forming coating solution was prepared.
(2) Preparation of coating solution for forming acrylic resin layer (B) Acrylic copolymer (e) solution (weight average molecular weight 150,000, solid content concentration) of methyl methacrylate: t-butyl methacrylate mass ratio = 95: 5 25 parts by mass) by mixing 2.5 parts by mass of 100 parts by mass of diphenoxyphosphate ester of bisphenol A [trade name “CR-741” manufactured by Daihachi Chemical Industry Co., Ltd.] as a plasticizer. (B) A forming coating solution was prepared.
(3) Production of Polarizer Polyvinyl alcohol film [manufactured by Nippon Synthetic Chemical Co., Ltd., trade name “Nippon Vinylon” on a 30 ° C. aqueous solution comprising 1000 parts by mass of water, 10 parts by mass of iodine and 100 parts by mass of potassium iodide. ]] Was soaked for 3 minutes to stain and adsorb iodine. Next, the film after immersion was immersed in a 5% by mass boric acid aqueous solution at 50 ° C., and uniaxially stretched 6 times in the major axis direction of the film. During this time, the immersion time in the boric acid aqueous solution was 5 minutes. The film taken out from the boric acid aqueous solution was washed by immersing it in water at 20 ° C. for 5 minutes in a uniaxially stretched state, and then dried to obtain a polarizer.
(4) Production of film forming material for protecting polarizer Using the layer (A) forming coating solution obtained in (1) above and the layer (B) forming coating solution obtained in (2) above, the thickness Acrylic adhesive layer (A) having a film thickness of 5 μm after heat drying from the release sheet side by a two-layer die on the release layer surface of a 38 μm release sheet made of PET [trade name “SP-PET 381031” manufactured by Lintec Corporation] A film forming material for protecting a polarizer was prepared by forming a 30 μm acrylic resin layer (B).
(5) Production of polarizing plate On the surface of the acrylic resin layer (B) of the film forming material for protecting a polarizer produced in (4) above, a protective film made of PET with a thickness of 50 μm [manufactured by Lintec Co., Ltd., trade name “ SPF / A1A "] was affixed.
Next, the polarizer obtained in (3) above was bonded to the surface from which the release sheet was peeled off, and ultraviolet rays were irradiated from the PET protective film side with a light amount of 300 mJ / cm ² . Next, the release film is similarly peeled off to the surface where the polarizer layer (A) is not bonded, and the adhesive layer (A) is attached so that the adhesive layer (A) is in contact therewith, and ultraviolet rays are irradiated with a light amount of 300 mJ / cm ^2. A polarizing plate of “system resin layer (B ′) / acrylic adhesive layer (A ′) / polarizer / acrylic adhesive layer (A ′) / acrylic resin layer (B ′)” was produced.

Example 2
A film forming material for protecting a polarizer and a polarizing plate were prepared in the same manner as in Example 1 except that the preparation of the coating solution for forming the acrylic resin layer (B) was changed as follows.
<Preparation of coating liquid for forming acrylic resin layer (B)>
An acrylic copolymer (e) (methyl methacrylate: t-butyl methacrylate mass ratio = 80: 20 (weight average molecular weight 80,000, solid content concentration 25 mass%) was prepared.

Example 3
A film forming material for protecting a polarizer and a polarizing plate were prepared in the same manner as in Example 1 except that the preparation of the coating solution for forming the acrylic resin layer (B) was changed as follows.
<Preparation of coating liquid for forming acrylic resin layer (B)>
Methyl methacrylate: t-butyl methacrylate mass ratio = 95: 5 acrylic copolymer (e) (weight average molecular weight 100,000, solid content concentration 25% by mass) 100 parts by mass of UV curable bifunctional urethane acrylate [Japan Made by Synthetic Chemical Co., Ltd., trade name “purple light UV-3520TL”, solid content concentration: 70% by mass] and 3.5 parts by mass, and 1-hydroxycyclohexyl phenyl ketone [manufactured by Ciba Specialty Chemicals Co., Ltd. as a photopolymerization initiator The coating solution for forming the layer (B) was prepared by mixing 0.15 parts by weight of “Irgacure 184”.

Example 4
A film forming material for protecting a polarizer and a polarizing plate were produced in the same manner as in Example 1 except that the preparation of the acrylic adhesive layer (A) in Example 1 was changed as follows.
<Preparation of adhesive layer (A) forming coating solution>
Tris (acryloxyethyl) isocyanurate (trade name “Aronix M-315” manufactured by Toagosei Co., Ltd., molecular weight 578), which is an ultraviolet curable polyfunctional acrylate of the coating liquid for forming the layer (A) in Example 1. Coating solution for forming the layer (A) in the same manner as in Example 1 except that 3 parts by mass of acryloylmorpholine [reagent, solids concentration 100%] was used instead of 3.5 parts by mass of solids concentration 100%. Was prepared.

Example 5
In Example 1, an acrylic pressure-sensitive adhesive layer (A) and an acrylic resin layer (B) were formed only on one side of the polarizer to obtain a polarizing plate.

Example 6
A film for protecting a polarizer as in Example 1, except that the preparation of the coating liquid for forming the acrylic adhesive layer (A) and the preparation of the coating liquid for forming the acrylic resin layer (B) were changed as follows. A forming material and a polarizing plate were prepared.
<Preparation of Acrylic Adhesive Layer (A) Forming Coating Liquid>
Add 2 parts by weight of methacryloyloxyethyl isocyanate to 5 parts by weight of a copolymer solution of butyl acrylate: acrylic acid mass ratio = 90: 10 (weight average molecular weight Mw: 1,500,000, solid content concentration 15% by weight) at 25 ° C. 7 parts by mass of a copolymer solution obtained by addition reaction for 24 hours and a copolymer solution of butyl acrylate: 2-hydroxyethyl acrylate mass ratio = 98: 2 (weight average molecular weight Mw: 1,500,000, solid concentration 15 80% by mass) and 20 parts by mass of a copolymer solution of butyl acrylate: acrylic acid mass ratio = 90: 10 (weight average molecular weight Mw: 1,500,000, solid content concentration 15% by mass), and UV curable polyfunctional. Tris (acryloxyethyl) isocyanurate [made by Toa Gosei Co., Ltd., trade name “Aronix M-315”, molecular weight 578, which is an acrylate Solid content concentration: 100%] 3.5 parts by mass were mixed. Furthermore, as a photopolymerization initiator, a mixture of benzophenone and 1-hydroxycyclohexyl phenyl ketone in a mass ratio of 1: 1 [Ciba Specialty Chemicals, trade name “Irgacure 500”] 0.20 part by mass and isocyanate By adding and mixing 0.075 parts by mass of a trimethylolpropane-modified tolylene diisocyanate-based cross-linking agent [trade name [Coronate L] solid content concentration: 75% by mass] made of Nippon Polyurethane Co., Ltd. A layer (A) forming coating solution was prepared.
<Preparation of coating liquid for forming acrylic resin layer (B)>
20 parts by mass of methacryloyloxyethyl isocyanate is added to 100 parts by mass of an acrylic copolymer solution (methyl methacrylate: 2-hydroxyethyl acrylate mass ratio = 90: 10, weight average molecular weight 100,000, solid content concentration 25% by mass), Furthermore, 0.01 parts by mass of dibutyltin dilaurate as a catalyst was added, and the copolymer (e) solution obtained by addition reaction at 25 ° C. for 24 hours was further added to a diphenoxyphosphate ester of bisphenol A as a plasticizer [ A coating solution for forming a layer (B) was prepared by mixing 2.5 parts by mass of Daihachi Chemical Industry Co., Ltd., trade name “CR-741”].

Comparative Example 1
In Example 1, without using a two-layer die, an acrylic adhesive layer (A) was formed using a Meyer bar so that the film thickness after drying was 5 μm, and the resin layer (B) was triacetylated. A film forming material for protecting a polarizer and a polarizing plate were produced in the same manner as in Example 1 except that the film was changed to a cellulose film [manufactured by Fuji Film Co., Ltd., trade name “TD40UL”].
The evaluation results of various characteristics in Examples 1 to 4 and 6 and Comparative Example 1 are shown in Table 1.

The polarizer protective film-forming material of the present invention has an optically isotropic layer having an acrylic resin layer having excellent durability such as hydrolysis resistance and an acrylic adhesive layer having excellent adhesion to the polarizer. It is used as a material for forming a polarizer protective film comprising a laminate.
The polarizer protective film of the present invention can provide a polarizing plate in which a polarizer is sandwiched between the protective films.

Claims (12)

Acrylic adhesive layer (A) having a thickness of 1 to 30 μm having a storage elastic modulus G ′ at 23 ° C. before irradiation with an active energy ray of 0.01 to 0.3 MPa, and an acrylic resin layer having a thickness of 10 to 100 μm ( A film forming material for protecting a polarizer having B),
The said acrylic adhesion layer (A) consists of 5-40 mass% of active energy ray hardening-type nitrogen-containing heterocyclic compounds (a), and (meth) acrylic acid ester copolymer (b) 95-60 mass%. The acrylic resin layer (B) is formed from a composition containing a combination, and the mass ratio of the methyl methacrylate unit (c) and at least one other (meth) acrylic acid ester unit (d). A film for protecting a polarizer, comprising a composition containing 80% by mass or more of a copolymer (e) having a weight average molecular weight of 50,000 to 300,000 in a ratio of 60:40 to 99: 1. Forming material.   The film forming material for protecting a polarizer according to claim 1, wherein the acrylic adhesive layer (A) has a storage elastic modulus G ′ at 23 ° C. after irradiation with active energy rays of 0.4 to 5 MPa.   The film forming material for protecting a polarizer according to claim 1 or 2, wherein the (meth) acrylic acid ester unit (d) in the copolymer (e) has an ethylenic double bond in a side chain.   The film forming material for protecting a polarizer according to claim 3, wherein the content of the unit containing an ethylenic double bond in the copolymer (e) is 0.5 to 20 mol%.   The (meth) acrylic acid ester copolymer (b) in the composition which forms an acrylic adhesion layer (A) has an ethylenic double bond in a side chain in any one of Claims 1-4. Film forming material for polarizer protection.   The film forming material for protecting a polarizer according to claim 5, wherein the content of the unit containing an ethylenic double bond in the copolymer (b) is 0.5 to 15 mol%.   The film forming material for protecting a polarizer according to any one of claims 1 to 6, wherein a release sheet is attached to the surface of the acrylic adhesive layer (A).   A film for protecting a polarizer obtained by irradiating the film forming material for protecting a polarizer according to claim 1 with active energy rays.   In the laminate composed of the acrylic adhesive layer (A ′) and the acrylic resin layer (B ′) after irradiation with the active energy ray, the in-plane retardation in the measurement from the acrylic resin layer (B ′) side is 10 nm. The film for protecting a polarizer according to claim 8, which is as follows.   The polarizer is sandwiched between the polarizer protective films so that both sides of the polarizer are in contact with the acrylic adhesive layer (A ′) in the polarizer protective film according to claim 8 or 9. A characteristic polarizing plate.   Active energy is obtained by sandwiching the polarizer with the material so that the acrylic adhesive layer (A) in the polarizer protective film-forming material according to any one of claims 1 to 7 is in contact with the polarizer on both sides. A polarizing plate characterized by being irradiated with a wire.   (A) A step of sequentially laminating the acrylic adhesive layer (A) and the acrylic resin layer (B) on one side of the process sheet, and (b) a step of attaching a protective film on the surface of the acrylic resin layer (B). , (C) peeling the process sheet and bonding the polarizer to the exposed acrylic adhesive layer (A) surface; and (d) an acrylic resin layer (B) and an acrylic adhesive layer (A). The manufacturing method of the polarizing plate characterized by including the process of irradiating an active energy ray to the laminated body with a polarizer.

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