JP6408046B2 - Photocurable adhesive, polarizing plate and laminated optical member using the same - Google Patents

Description

  The present invention relates to a photocurable adhesive for adhering a thermoplastic resin film to a polyvinyl alcohol polarizer, and a polarizing plate and a laminated optical member using the same.

  The polarizing plate is useful as one of the optical components that constitute the liquid crystal display device. A polarizing plate usually has a structure in which protective films are laminated on both sides of a polarizer, and is incorporated into a liquid crystal display device. It is also known that a protective film is provided only on one side of a polarizer, but in many cases, a film having another optical function is bonded to the other side as a protective film, not just a protective film. The As a method for producing a polarizer, a method in which a uniaxially stretched polyvinyl alcohol-based resin film dyed with a dichroic dye is treated with boric acid, washed with water and dried is widely adopted.

  Usually, a protective film is bonded to the polarizer immediately after the above water washing and drying. This is because the dried polarizer has a weak physical strength, and once it is wound, there is a problem that it is easily broken in the processing direction. Therefore, usually, a water-based adhesive that is an aqueous solution of a polyvinyl alcohol resin is immediately applied to the polarizer after drying, and the protective film is simultaneously bonded to both surfaces of the polarizer via this adhesive. Usually, a triacetyl cellulose film having a thickness of 30 to 100 μm is used as the protective film.

  Triacetylcellulose is excellent in transparency, easy to form various surface treatment layers and optical functional layers on its surface, and has a high moisture permeability, after being adhered to a polarizer using an aqueous adhesive as described above. While having excellent advantages as a protective film such that drying can be performed smoothly, due to the high moisture permeability, the polarizing plate using this as a protective film is, for example, 70 ° C. and 90% relative humidity under humid heat. There was a problem that deterioration was likely to occur under the conditions. Therefore, it is also known to use an amorphous polyolefin resin having a lower moisture permeability than that of triacetyl cellulose, for example, a norbornene resin as a representative example as a protective film.

  When bonding a protective film made of a resin with low moisture permeability to a polyvinyl alcohol polarizer, an aqueous solution of a polyvinyl alcohol resin conventionally used for bonding a polyvinyl alcohol polarizer and a triacetyl cellulose film is used as an adhesive. There are problems that the adhesive strength is not sufficient or the appearance of the obtained polarizing plate becomes poor. This is because a resin film having low moisture permeability is generally hydrophobic, and water as a solvent cannot be sufficiently dried due to low moisture permeability. On the other hand, it is also known to bond different types of protective films on both sides of the polarizer. For example, a protective film made of a resin with low moisture permeability such as an amorphous polyolefin resin is bonded to one surface of a polarizer, and a cellulose resin such as triacetyl cellulose is bonded to the other surface of the polarizer. There is also a proposal for adhering a protective film made of a highly moisture-permeable resin.

  Therefore, a high adhesive force is given between the protective film made of a resin with low moisture permeability and the polyvinyl alcohol polarizer, and it is also high between a resin with high moisture permeability such as a cellulose resin and the polyvinyl alcohol polarizer. There is an attempt to use a photocurable adhesive as an adhesive that gives adhesive strength. For example, JP 2008-257199 A (Patent Document 1) discloses a photocurable adhesive in which an alicyclic epoxy compound and an epoxy compound having no alicyclic epoxy group are combined and a photocationic polymerization initiator is further blended. Although the technique which uses an agent for adhesion | attachment with a polarizer and a protective film is disclosed, adhesive force is not enough and the polarizer and the protective film may peel off in the case of a cutting process.

  Japanese Patent Application Laid-Open No. 2014-037477 (Patent Document 2) proposes a photocurable adhesive containing a naphthalene type epoxy resin. However, it is colored by light irradiation and is not suitable for optical use. Met.

JP 2008-257199 A JP 2014-037477 A

  The present invention is a photo-curing adhesive for adhering a thermoplastic resin film to a polyvinyl alcohol polarizer, and the cured elastic layer of the adhesive layer has a high storage elastic modulus. It is an object of the present invention to provide a photo-curable adhesive that can be bonded to a resin film with a strong adhesion, and that can produce a highly durable polarizing plate. Another object of the present invention is to provide a polarizing plate obtained by laminating a polyvinyl alcohol-based polarizer and a thermoplastic resin film using the above-mentioned photocurable adhesive, and another optical layer laminated on the polarizing plate. An object of the present invention is to provide a laminated optical member suitably used for a liquid crystal display device.

The present invention provides the following photocurable adhesive, polarizing plate, and laminated optical member.
[1] A photocurable adhesive for adhering a thermoplastic resin film to a polyvinyl alcohol polarizer,
The main component is an epoxy compound containing no aromatic ring,
A photocationic curable component (A) and a photocationic polymerization initiator (B),
The photocationic curable component (A) has the following formula (I):

(In the formula, n represents an integer of 1 or more. V represents an n-valent group including a condensed ring composed of an alicyclic ring.)
The photocurable adhesive agent containing the 1st epoxy compound (A1) represented by these.

[2] The photocationic curable component (A) is based on the total amount thereof.
5 to 85% by weight of the first epoxy compound (A1), and the following formula (II):

(In the formula, R ¹ and R ² each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and when the alkyl group has 3 or more carbon atoms, it may have an alicyclic structure. Often;
X is an oxygen atom, an alkanediyl group having 1 to 6 carbon atoms, or the following formulas (IIa) to (IId):

In which Y ¹ to Y ⁴ each represent an alkanediyl group having 1 to 20 carbon atoms, and in the case of 3 or more carbon atoms, an alicyclic structure is present. May be;
a and b each represents an integer of 0 to 20. )
The photocurable adhesive according to [1], which contains 15 to 85% by weight of the second epoxy compound (A2) represented by the formula:

[3] Furthermore, the photocationic curable component (A) is based on the total amount thereof.
Formula (III) below:

(Wherein, Z is branched alkylene group having 3 to 8 carbon atoms, or the formula ^{_{-C m H 2m -Z 1 -C n}} H 2n - represents a divalent group represented by wherein -Z ¹ - is , -O-, -CO-O- or -O-CO-, one of m and n represents an integer of 1 or more and the other represents an integer of 2 or more, and the sum of the two is 8 or less, and C _m One of H _2m and C _n H _2n represents a branched divalent saturated hydrocarbon group.)
The photocurable adhesive according to [1] or [2], containing 1 to 70% by weight of the third epoxy compound (A3) represented by the formula:

  [4] Furthermore, with respect to 100 parts by weight of the photocationic curable component (A), the following formula (IVa):

(In the formula, R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxyalkyl group having 2 to 12 carbon atoms, and R ⁵ represents a hydrogen atom or 1 to 1 carbon atoms. 6 represents an alkyl group.)
And an anthracene compound represented by the following formula (IVb):

(In the formula, R ⁶ and R ⁷ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.)
The photocurable adhesive according to any one of [1] to [3], containing 0.1 to 5 parts by weight of one or more compounds selected from the group consisting of naphthalene compounds represented by:

  [5] The photocuring according to any one of [1] to [4], wherein the water content is more than 0 parts by weight and 4 parts by weight or less with respect to 100 parts by weight of the photocationic curable component (A). Adhesive.

[6] A polyvinyl alcohol polarizer,
A thermoplastic resin film laminated on at least one surface of the polyvinyl alcohol polarizer through a cured product of the photocurable adhesive according to any one of [1] to [5];
A polarizing plate including

  [7] A laminated optical member comprising a laminate of the polarizing plate according to [6] and one or more other optical layers.

  [8] The laminated optical member according to [7], wherein the other optical layer includes a retardation plate.

  ADVANTAGE OF THE INVENTION According to this invention, it is hard to dissolve a thermoplastic resin film, the storage elastic modulus of the adhesive bond layer which is hardened | cured material is high, and it can adhere | attach a polyvinyl alcohol type polarizer and a thermoplastic resin film with a strong adhesive force. Thus, it is possible to provide a photocurable adhesive capable of producing a highly durable polarizing plate. According to the photocurable adhesive of the present invention, it is possible to provide a polarizing plate excellent in durability and a laminated optical member using the same. Therefore, according to the photocurable adhesive of the present invention, the polarizer and the thermoplastic resin film are less likely to be peeled even during the cutting process, for example, a polarizing plate in which the polarizer is less likely to be broken by a thermal cycle test, It is possible to provide a laminated optical member using the same.

<Photocurable adhesive>
The photocurable adhesive according to the present invention is an adhesive for adhering a thermoplastic resin film to a polyvinyl alcohol-based polarizer, and is mainly composed of an epoxy compound containing no aromatic ring, and a photocationic curable component (A And a cationic photopolymerization initiator (B).

  The photocurable adhesive has an epoxy compound containing no aromatic ring as a main component. An epoxy compound that does not contain an aromatic ring is an epoxy compound other than an aromatic epoxy compound, and is hereinafter referred to as an aliphatic epoxy compound. An “epoxy compound” is a compound having at least one epoxy group in the molecule. The aliphatic epoxy compound as the main component may contain two or more epoxy compounds. The “main component” means that the content of the aliphatic epoxy compound is 50% by weight or more in 100% by weight of the photocurable adhesive. The content of the aliphatic epoxy compound is preferably 60% by weight or more, more preferably 70% by weight or more, still more preferably 80% by weight or more, and still more preferably 90% by weight or more.

  The aliphatic epoxy compound may be an epoxy compound having an alicyclic ring, or does not contain an alicyclic ring, and is composed of only a linear hydrocarbon structure and / or a branched hydrocarbon structure. Epoxy compounds may be used. In addition, the aliphatic epoxy compound may contain an unsaturated bond such as a double bond, or a hetero atom other than the oxygen atom contained in the epoxy group (oxygen atom, nitrogen atom, sulfur atom, halogen atom, etc.). Further, it may be included.

(1) Photocationic curable component (A)
The photocationic curable component (A) is a component that provides an adhesive force by polymerization and curing by irradiation with active energy rays, and contains the first epoxy compound (A1) described in detail below. The photocationically curable component (A) preferably further contains a second epoxy compound (A2) or a third epoxy compound (A3) described in detail below together with the first epoxy compound (A1), and more preferably In addition to the first epoxy compound (A1), at least the second epoxy compound (A2) is further contained. The photocationic curable component (A) further preferably contains a second epoxy compound (A2) and a third epoxy compound (A3) together with the first epoxy compound (A1).

(1-1) First epoxy compound (A1)
The first epoxy compound (A1) has the following formula (I):

It is a glycidyl compound represented by these. In the formula (I), n represents the number of glycidyloxy groups bonded to V and is an integer of 1 or more. V represents an n-valent group containing a condensed ring composed of an alicyclic ring. “A condensed ring composed of an alicyclic ring” refers to a condensed ring constructed only by an alicyclic ring, in other words, a condensed ring that is not an aromatic ring or does not include an aromatic ring. The condensed ring may be bicyclic, tricyclic or tetracyclic or higher polycyclic, but is preferably bicyclic or tricyclic. . The condensed ring may contain an unsaturated bond such as a double bond, a hetero atom (oxygen atom, nitrogen atom, sulfur atom, halogen atom and the like), and other substituents (alkyl group and the like). The number of carbon atoms of each alicyclic ring constituting the condensed ring is usually 4 to 8, and preferably 5 or 6.

  The fact that the photocationic curable component (A) contains the first epoxy compound (A1) means that the ability of the photocurable adhesive to dissolve the thermoplastic resin film adhered to the polyvinyl alcohol polarizer (hereinafter referred to as this ability). Is also referred to as “solubility”), and is advantageous in reducing the storage elastic modulus of the cured product of the photocurable adhesive, and the adhesion between the polyvinyl alcohol polarizer and the thermoplastic resin film. It is advantageous in increasing power. It is also advantageous for enhancing the color resistance of the photocurable adhesive. For example, when the n-valent group V contains an aromatic condensed ring, the photocurable adhesive containing a relatively large amount of such an epoxy compound has the aromatic condensed ring itself in the visible light region. Coloring may occur to show absorption. In addition, even when the n-valent group V contains an aromatic condensed ring that does not absorb in the visible light region, it causes a reaction that produces a dimer or higher oligomer by irradiation with active energy rays. There is a high possibility of coloring the photocurable adhesive.

  The n-valent group V may be an n-valent group composed of a condensed ring composed of an alicyclic ring (for example, a condensed ring such as a polycyclic hydrocarbon type or a bridged hydrocarbon type). It may be an n-valent group composed of a condensed ring and one or more linking groups bonded thereto. The linking group is a group that links the condensed ring and the glycidyloxy group of the first epoxy compound (A1). When the n-valent group V is composed of the condensed ring and one or more linking groups bonded thereto, each of the condensed ring and the linking group may have a bond with a glycidyloxy group. Only the linking group may have a bond.

  n is usually an integer of 6 or less, in view of increasing the storage elastic modulus and the adhesion, and further reducing the viscosity of the photocurable adhesive (photocurable adhesive before curing; the same applies hereinafter). From the viewpoint, it is preferably an integer of 1 to 4, more preferably 2 or 3.

Examples of the linking group that links the condensed ring and the glycidyloxy group of the first epoxy compound (A1) include a divalent aliphatic hydrocarbon group. The divalent aliphatic hydrocarbon group may contain an alicyclic ring, or does not contain an alicyclic ring, and is composed of only a linear hydrocarbon structure and / or a branched hydrocarbon structure. Also good. The divalent aliphatic hydrocarbon group is preferably an alkylene group having 1 to 8 carbon atoms, and more preferably an alkylene group having 1 to 4 carbon atoms. The number of carbon atoms is more preferably 1 to 3, and particularly preferably 1 or 2 (that is, a methylene group or an ethylene group). At least one CH ₂ group constituting the alkylene group may be substituted with an oxygen atom or a sulfur atom. The alkylene group may be linear or branched.

  Specific examples of the n-valent group V including a condensed ring composed of an alicyclic ring are as shown in the following table, for example. In the following table, each Q is independently a single bond or the above linking group. * Represents a bond with the glycidyloxy group of the first epoxy compound (A1). In addition, although all the specific examples of group V shown below are divalent groups (n = 2), they are not limited to divalent groups as described above.

  Further, examples of the group V include the following groups.

(1-2) Second epoxy compound (A2)
The second epoxy compound (A2) has the following formula (II):

It is an alicyclic diepoxy compound represented by these. In addition to the first epoxy compound (A1), the photocationic curable component (A) further contains the second epoxy compound (A2), and the storage elastic modulus of the cured product of the photocurable adhesive and polyvinyl alcohol This is advantageous in increasing the adhesion between the system polarizer and the thermoplastic resin film. It is also advantageous for enhancing the color resistance of the photocurable adhesive.

In the above formula (II), R ¹ and R ² each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and when the alkyl group has 3 or more carbon atoms, it has an alicyclic structure. It may be. This alkyl group has the 1-position of the cyclohexane ring bonded to X in the formula (II) as the 1-position (therefore, the positions of the epoxy groups in the two cyclohexane rings are both 3,4-position). It can be bonded to any position of the -6-position. Of course, this alkyl group may be linear, or may be branched when it has 3 or more carbon atoms. Moreover, as above-mentioned, in C3 or more, you may have an alicyclic structure. Typical examples of the alkyl group having an alicyclic structure include a cyclopentyl group and a cyclohexyl group.

  In the above formula (II), X connecting two 3,4-epoxycyclohexane rings is an oxygen atom, an alkanediyl group having 1 to 6 carbon atoms, or the following formulas (IIa) to (IId):

It is a bivalent group represented by either. The alkanediyl group is a concept including alkylene and alkylidene, and the alkylene may be linear, or may be branched when having 3 or more carbon atoms, and has an alicyclic structure. May be. A in formula (IIa) and b in formula (IId) each represent an integer of 0-20. Each of a and b is preferably an integer of 0 to 12, more preferably an integer of 0 to 8, and further preferably an integer of 0 to 4.

When X is a divalent group represented by any one of the above formulas (IIa) to (IId), the linking groups Y ¹ , Y ² , Y ³ and Y ⁴ in each formula each have 1 to 20 carbon atoms. When the alkanediyl group has 3 or more carbon atoms, it may have an alicyclic structure. Of course, these alkanediyl groups may be linear, or in the case of 3 or more carbon atoms, they may be branched. Moreover, as above-mentioned, in C3 or more, you may have an alicyclic structure. Typical examples of the alkanediyl group having an alicyclic structure include a cyclopentylene group and a cyclohexylene group.

The second epoxy compound (A2) represented by the formula (II) will be specifically described. The compound in which X in the formula (II) is a divalent group represented by the above formula (IIa) and a in the formula is 0 is 3,4-epoxycyclohexylmethanol (the cyclohexane ring has 1 carbon atom). -6 alkyl group may be bonded) and 3,4-epoxycyclohexanecarboxylic acid (an alkyl group having 1 to 6 carbon atoms may be bonded to the cyclohexane ring). It is. For example,
3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate [formula (II) (wherein X is a divalent group represented by formula (IIa) where a = 0), R ¹ = R ² = H compound],
3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclohexanecarboxylate [in formula (II) having the same X as above, R ¹ = 6-methyl, R ² = 6-methyl Compound〕,
3,4-epoxy-1-methylcyclohexylmethyl 3,4-epoxy-1-methylcyclohexanecarboxylate [in formula (II) having the same X as above, R ¹ = 1-methyl, R ² = 1-methyl Compound〕,
3,4-epoxy-3-methylcyclohexylmethyl 3,4-epoxy-3-methylcyclohexanecarboxylate [in formula (II) having the same X as above, R ¹ = 3-methyl, R ² = 3-methyl Compound〕
Etc.

  The compound in which X in formula (II) is a divalent group represented by formula (IIb) is an alkylene glycol and 3,4-epoxycyclohexanecarboxylic acid (the alkyl group having 1 to 6 carbon atoms is present on the cyclohexane ring). Esterified product).

  The compound in which X in the formula (II) is a divalent group represented by the formula (IIc) includes aliphatic dicarboxylic acids and 3,4-epoxycyclohexylmethanol (the alkyl group having 1 to 6 carbon atoms is present in the cyclohexane ring). Esterified product).

  A compound in which X in formula (II) is a divalent group represented by formula (IId) is 3,4-epoxycyclohexylmethanol (even if an alkyl group having 1 to 6 carbon atoms is bonded to the cyclohexane ring). Or an alkylene glycol or polyalkylene glycol and 3,4-epoxycyclohexylmethanol (the alkyl group having 1 to 6 carbon atoms is bonded to the cyclohexane ring). And etherified product (when b> 0).

  Among them, the alicyclic diepoxy compound in which X in the formula (II) is a divalent group represented by the above formula (IIa) is a storage elastic modulus of a cured product of a photocurable adhesive, and a polyvinyl alcohol polarizer. It is one of the compounds suitable for increasing the adhesion between the resin film and the thermoplastic resin film. In the alicyclic diepoxy compound in which X in the formula (II) is a divalent group represented by the formula (IIa), a in the formula (IIa) is preferably an integer of 0 to 4, more preferably Is an integer of 0 to 2, more preferably 0 or 1.

(1-3) Third epoxy compound (A3)
The third epoxy compound (A3) has the following formula (III):

It is a diglycidyl compound represented by these. The photocationic curable component (A) further contains a third epoxy compound (A3) in addition to the first epoxy compound (A1). In particular, in addition to the first epoxy compound (A1), the second epoxy compound Further containing (A2) and the third epoxy compound (A3) enhances the storage elastic modulus of the cured product of the photocurable adhesive and the adhesion between the polyvinyl alcohol polarizer and the thermoplastic resin film. This is advantageous. It is also advantageous for enhancing the color resistance of the photocurable adhesive.

In the above formula (III), Z is a branched alkylene group having 3 to 8 carbon atoms or a divalent group represented by the formula —C _m H _2m —Z ¹ —C _n H _2n —. Here, —Z ¹ — is —O—, —C (═O) —O— or —O—C (═O) —, and one of m and n is an integer of 1 or more and the other is an integer of 2 or more. However, the sum of both is 8 or less, and one of C _m H _2m and C _n H _2n is a branched divalent saturated hydrocarbon group. In addition to the first epoxy compound (A1), the photocation curable component (A) further contains a third epoxy compound (A3) containing a branched chain structure in Z, in order to reduce the dissolving power. It is also advantageous for reducing the viscosity of the photocurable adhesive.

  By reducing the dissolving power of the photo-curing adhesive, it is possible to suppress a defect that causes bubble defects in the cured adhesive layer. This is presumed to be because an increase in viscosity of the photocurable adhesive due to the thermoplastic resin film being dissolved in the photocurable adhesive can be suppressed.

  The number of carbon atoms of the branched alkylene group is preferably an integer of 3 to 6 from the viewpoint of increasing the storage elastic modulus and the adhesion, and further from the viewpoint of reducing the viscosity of the photocurable adhesive.

  In the formula (III), the compound in which Z is a branched alkylene group is a diglycidyl ether of a branched alkylene glycol. Specific examples include propylene glycol diglycidyl ether, 1,3-butanediol diglycidyl ether, 1,2-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 3-methyl-1,5-pentanediol. There are diglycidyl ether, 2-methyl-1,8-octanediol diglycidyl ether, 1,4-cyclohexanedimethanol and the like.

In the formula (III), a compound in which Z is a divalent group represented by the above formula —C _m H _2m —Z ¹ —C _n H _2n —, wherein Z is a branched alkylene group, This corresponds to the case where the C—C bond is interrupted by —O—, —C (═O) —O— or —O—C (═O) —.

  Among them, the diglycidyl compound in which Z in the formula (III) is a branched alkylene group having 3 to 8 carbon atoms, preferably 3 to 6 carbon atoms, is a viewpoint of increasing the storage elastic modulus and the adhesion force, and further is a photocurable adhesive. From the viewpoint of lowering the viscosity and reducing the dissolving power, it is one of the preferred compounds.

(1-4) Content of First to Third Epoxy Compounds (A1) to (A3) The photocationic curable component (A) may be composed of only the first epoxy compound (A1). However, from the viewpoint of increasing the storage elastic modulus and the adhesion, the photocation curable component (A) is preferably the second epoxy compound (A2) or the third epoxy compound (A1) together with the first epoxy compound (A1). A3) is further contained, more preferably, at least the second epoxy compound (A2) is further contained together with the first epoxy compound (A1), and further preferably, the second epoxy compound is contained together with the first epoxy compound (A1). It further contains (A2) and a third epoxy compound (A3).

  From the viewpoint of increasing the storage elastic modulus and the adhesion, the content of the first epoxy compound (A1) in the photocationic curable component (A) is based on the total amount of the photocationic curable component (A), that is, In 100% by weight of the photocationic curable component (A), preferably 5 to 85% by weight, more preferably 10 to 50% by weight, still more preferably 12 to 40% by weight, still more preferably 15 to 30% by weight. In addition, it is preferable to contain the second epoxy compound (A2) or the second epoxy compound (A2) and the third epoxy compound (A3) in the photocationically curable component (A). When the content of the first epoxy compound (A1) in the photocationic curable component (A) is too small, the dissolving power becomes large and bubble defects are likely to occur, and the storage elastic modulus tends to be low. In addition, if the content of the first epoxy compound (A1) in the photocationic curable component (A) is too large, the viscosity of the photocurable adhesive tends to increase, and the shrinkage of curing upon irradiation with active energy rays increases. Adhesion tends to be low.

  When the photocationic curable component (A) contains the second epoxy compound (A2), the content of the second epoxy compound (A2) in the photocationic curable component (A) is from the viewpoint of increasing the storage elastic modulus. , Preferably 15 to 85% by weight, more preferably 20 to 85% by weight, still more preferably 25 to 60% by weight, based on the total amount of the photocationic curable component (A), and still more Preferably it is 30 to 50% by weight. If the content of the second epoxy compound (A2) in the photocationic curable component (A) is too small, curing at the time of active energy ray irradiation tends to be insufficient, whereby a polyvinyl alcohol polarizer and a thermoplastic resin film The adhesion between the two tends to be low. The content of the second epoxy compound (A2) in the photocationic curable component (A) may exceed 85% by weight, but 85% is required to contain the third epoxy compound (A3) in a sufficient amount. It is preferable to set the weight% or less. Further, from the viewpoint of enhancing the adhesion, the content of the second epoxy compound (A2) in the photocation curable component (A) is 65% by weight based on the total amount of the photo cation curable component (A). Preferably, the content is less than 60% by weight, more preferably less than 60% by weight, and still more preferably less than 55% by weight.

  When the photocationic curable component (A) contains the third epoxy compound (A3), the content of the third epoxy compound (A3) in the photocationic curable component (A) is the photocationic curable component (A). From the viewpoint of reducing the above viscosity based on the total amount, preferably 1 to 70% by weight, more preferably 5 to 60% by weight, still more preferably 5 to 55% by weight, and still more preferably. Is from 10 to 50% by weight. Inclusion of 1% by weight or more of the third epoxy compound (A3) is advantageous also from the viewpoint of reducing the viscosity of the photocurable adhesive and increasing the adhesion. In order to further reduce the viscosity of the photocurable adhesive before curing and to improve the adhesion between the polarizer and the thermoplastic resin film by the cured product more effectively, the photocationic curable component (A) The content of the third epoxy compound (A3) is preferably 25% by weight or more based on the total amount of If the content of the third epoxy compound (A3) in the photocationic curable component (A) is too large, curing at the time of irradiation with active energy rays tends to be insufficient, and this tends to reduce the adhesion. Further, from the viewpoint of the storage elastic modulus and the dissolving power, the content of the third epoxy compound (A3) in the photocationic curable component (A) is based on the total amount of the photocationic curable component (A). 60% by weight or less, more preferably 55% by weight or less, and even more preferably 50% by weight or less.

  The total content of the first epoxy compound (A1), the second epoxy compound (A2) and the third epoxy compound (A3) in the content of the aliphatic epoxy compound is from the viewpoint of increasing the storage elastic modulus and the adhesion. In 100% by weight of the aliphatic epoxy compound, it is usually 50% by weight or more, preferably 60% by weight or more, more preferably 70% by weight or more, further preferably 80% by weight or more, and still more preferably 90% by weight or more. Particularly preferred is 95% by weight or more, and most preferred is 100% by weight.

(1-5) Other Photocationic Curing Component The photocationic curing component (A) is a light other than the first epoxy compound (A1), the second epoxy compound (A2), and the third epoxy compound (A3). Cationic curable compounds can be included. Other photocationic curable compounds include oxetane compounds; vinyl ether compounds; epoxy resins other than aliphatic epoxy compounds (aromatic epoxy compounds); first epoxy compounds (A1), second epoxy compounds (A2) and Aliphatic epoxy compounds other than 3 epoxy compounds (A3), etc. are mentioned.

(2) Photocationic polymerization initiator (B)
The photocurable adhesive contains a photocationic polymerization initiator (B). Thereby, a photocationic curable component (A) can be hardened | cured by cationic polymerization by irradiation of an active energy ray, and an adhesive bond layer can be formed. The cationic photopolymerization initiator (B) generates a cationic species or a Lewis acid upon irradiation with active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams, and polymerizes the photocationic curable component (A). Is to start. Since the cationic photopolymerization initiator (B) acts catalytically by light, it is excellent in storage stability and workability even when mixed with the cationic photocurable component (A). Examples of compounds that generate cationic species and Lewis acids upon irradiation with active energy rays that can be used as the photocationic polymerization initiator (B) include aromatic diazonium salts; onium salts such as aromatic iodonium salts and aromatic sulfonium salts; Examples thereof include iron-arene complexes.

As an aromatic diazonium salt, for example,
Benzenediazonium hexafluoroantimonate,
Benzenediazonium hexafluorophosphate,
Examples thereof include benzenediazonium hexafluoroborate.

As an aromatic iodonium salt, for example,
Diphenyliodonium tetrakis (pentafluorophenyl) borate,
Diphenyliodonium hexafluorophosphate,
Diphenyliodonium hexafluoroantimonate,
Di (4-nonylphenyl) iodonium hexafluorophosphate is mentioned.

As an aromatic sulfonium salt, for example,
Triphenylsulfonium hexafluorophosphate,
Triphenylsulfonium hexafluoroantimonate,
Triphenylsulfonium tetrakis (pentafluorophenyl) borate,
4,4′-bis [diphenylsulfonio] diphenyl sulfide bishexafluorophosphate,
4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide bishexafluoroantimonate,
4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide bishexafluorophosphate,
7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate,
7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone tetrakis (pentafluorophenyl) borate,
4-phenylcarbonyl-4′-diphenylsulfonio-diphenyl sulfide hexafluorophosphate,
4- (p-tert-butylphenylcarbonyl) -4′-diphenylsulfonio-diphenyl sulfide hexafluoroantimonate,
4- (p-tert-butylphenylcarbonyl) -4′-di (p-toluyl) sulfonio-diphenyl sulfide tetrakis (pentafluorophenyl) borate.

As an iron-arene complex, for example,
Xylene-cyclopentadienyl iron (II) hexafluoroantimonate,
Cumene-cyclopentadienyl iron (II) hexafluorophosphate,
Xylene-cyclopentadienyl iron (II) tris (trifluoromethylsulfonyl) methanide.

  The photocationic polymerization initiator (B) may be used alone or in combination of two or more. Among these, aromatic sulfonium salts are particularly preferably used because they have ultraviolet absorption characteristics even in the wavelength region near 300 nm, and thus can provide an adhesive layer having excellent curability and good mechanical strength and adhesive strength. It is done.

  The content of the photocationic polymerization initiator (B) is preferably 1 to 10 parts by weight, more preferably 2 to 6 parts by weight, based on 100 parts by weight of the entire photocationic curable component (A). By containing 1 part by weight or more of the cationic photopolymerization initiator (B), the cationic photocuring component (A) can be sufficiently cured, and the resulting polarizing plate can have high mechanical strength and adhesive strength. it can. On the other hand, when the content is increased, the ionic substance in the cured product is increased, so that the hygroscopic property of the cured product is increased and the durability performance of the polarizing plate may be lowered. The content of B) is preferably 10 parts by weight or less with respect to 100 parts by weight of the photocationic curable component (A).

(3) Other component which can be mix | blended with photocurable adhesive The photocurable adhesive can contain the other component known to mix | blend with a general photocurable resin or an adhesive agent. Preferable examples of other components include a photosensitizer and a photosensitization aid. The photosensitizer is a compound that exhibits maximum absorption at a wavelength longer than the maximum absorption wavelength indicated by the photocationic polymerization initiator (B) and promotes the polymerization initiation reaction by the photocationic polymerization initiator (B). The photosensitizing assistant is a compound that further promotes the action of the photosensitizer. Depending on the type of thermoplastic resin film, it may be preferable to blend such a photosensitizer and further a photosensitization aid.

  Examples of the photosensitizer and the photosensitization aid include anthracene compounds and naphthalene compounds. Examples of the anthracene compound include those represented by the following formula (IVa).

In the formula, R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxyalkyl group having 2 to 12 carbon atoms, and R ⁵ represents a hydrogen atom or 1 to 6 carbon atoms. Represents an alkyl group. Specific examples of the anthracene compound represented by the above formula (IVa) include the following compounds.

9,10-dimethoxyanthracene,
9,10-diethoxyanthracene,
9,10-dipropoxyanthracene,
9,10-diisopropoxyanthracene,
9,10-dibutoxyanthracene,
9,10-dipentyloxyanthracene,
9,10-dihexyloxyanthracene,
9,10-bis (2-methoxyethoxy) anthracene,
9,10-bis (2-ethoxyethoxy) anthracene,
9,10-bis (2-butoxyethoxy) anthracene,
9,10-bis (3-butoxypropoxy) anthracene,
2-methyl- or 2-ethyl-9,10-dimethoxyanthracene,
2-methyl- or 2-ethyl-9,10-diethoxyanthracene,
2-methyl- or 2-ethyl-9,10-dipropoxyanthracene,
2-methyl- or 2-ethyl-9,10-diisopropoxyanthracene,
2-methyl- or 2-ethyl-9,10-dibutoxyanthracene,
2-methyl- or 2-ethyl-9,10-dipentyloxyanthracene,
2-methyl- or 2-ethyl-9,10-dihexyloxyanthracene and the like.

  As a naphthalene type compound, what is represented by the following Formula (IVb) is mentioned, for example.

In the formula, R ⁶ and R ⁷ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Specific examples of the naphthalene compound represented by the above formula (IVb) include the following compounds.

4-methoxy-1-naphthol,
4-ethoxy-1-naphthol,
4-propoxy-1-naphthol,
4-butoxy-1-naphthol,
4-hexyloxy-1-naphthol,
1,4-dimethoxynaphthalene,
1-ethoxy-4-methoxynaphthalene,
1,4-diethoxynaphthalene,
1,4-dipropoxynaphthalene,
1,4-dibutoxynaphthalene and the like.

  By mix | blending the above photosensitizers and photosensitization adjuvants with a photocurable adhesive agent, the sclerosis | hardenability of an adhesive agent can be improved compared with the case where it is not mix | blended. Such an effect can be expressed by blending 0.1 parts by weight or more of a photosensitizer and a photosensitizer with 100 parts by weight of the photocationic curable component (A).

  The content of the anthracene-based compound is set to 0.000 parts by weight with respect to 100 parts by weight of the photocationically curable component (A) from the viewpoint of maintaining the neutral gray of the polarizing plate and suppressing the problem of precipitation during low-temperature storage. It is preferable to set it as 1 to 0.3 weight part. Further, the content of the naphthalene compound is preferably 5 parts by weight or less with respect to 100 parts by weight of the photocationic curable component (A) from the viewpoint of suppressing problems such as precipitation at low temperature storage. It is more preferable to set it as a part or less.

  The photocurable adhesive may contain other additive components other than the photosensitizer and the photosensitizer as long as the effects of the present invention are not impaired. Other additive components include thermal cationic polymerization initiators, alcohol compounds (polyols, etc.), ion trapping agents, antioxidants, light stabilizers, chain transfer agents, tackifiers, thermoplastic resins, fillers, flow A regulator, a plasticizer, an antifoamer, a leveling agent, a pigment | dye, an organic solvent etc. can be mentioned. When the additive component is contained, the content is preferably 1000 parts by weight or less with respect to 100 parts by weight of the photocationically curable component (A).

(4) Water content of photocurable adhesive The photocurable adhesive may contain moisture. The water content is usually 4 parts by weight or less, preferably 3 parts by weight or less, more preferably less than 3 parts by weight with respect to 100 parts by weight of the photocationic curable component (A). By containing a slight amount of water exceeding 0 part by weight, the adhesive strength between the polyvinyl alcohol polarizer and the thermoplastic resin film may be improved. The water content is usually 0.01 parts by weight or more, preferably 0.03 parts by weight or more, more preferably 0.04 parts by weight with respect to 100 parts by weight of the photocationic curable component (A). That's it. However, if the water content is too high, separation between the photocurable adhesive and water occurs, making it impossible to uniformly apply the photocurable adhesive to the surface of the polarizer or thermoplastic resin film, The curability of the photo-curable adhesive may be deteriorated. Water may be intentionally added to the photocurable adhesive. In this case, although not particularly limited, purified water such as distilled water and pure water can be used. The moisture may be moisture derived from the raw material, moisture mixed in the manufacturing process, or the like. The water content of the photocurable adhesive is measured by the Karl Fischer capacity method.

(5) Physical Properties of Photocurable Adhesive The photocurable adhesive according to the present invention can have a low viscosity as described above, whereby a thermoplastic resin film can be applied to a polyvinyl alcohol polarizer. In pasting using a curable adhesive, excellent coating aptitude can be shown. Specifically, the photocurable adhesive which concerns on this invention can show the viscosity of the range of 2-300 mPa * s in 25 degreeC. Viscosity here is a viscosity in the state which does not contain a solvent substantially. When the viscosity is less than 2 mPa · s, the polarizer and the thermoplastic resin film may be peeled off during conveyance after bonding, and when the viscosity exceeds 300 mPa · s, the polarizer and the thermoplastic resin film are photocured. When laminating via an adhesive, especially when the adhesive layer is thin, air bubbles are easily mixed between the polarizer and the thermoplastic resin film, that is, in the adhesive layer. The viscosity is preferably 5 to 200 mPa · s, more preferably 10 to 150 mPa · s, still more preferably 100 mPa · s or less, and particularly preferably 80 mPa · s or less. The viscosity of the photocurable adhesive is measured using an E-type viscometer.

  The photocurable adhesive according to the present invention can be used for producing a polarizing plate by bonding a thermoplastic resin film to a polyvinyl alcohol polarizer. At this time, when the adhesive dissolves the thermoplastic resin film, as described above, the dissolution may cause bubble defects in the adhesive layer of the polarizing plate. As described above, the photocurable adhesive according to the present invention may have a small ability (dissolving power) to dissolve the thermoplastic resin film. The inclusion of the third epoxy compound (A3) in which Z in the formula (III) has a branched structure, preferably a branched alkylene group, is advantageous for suppressing an increase in the dissolving power. The photocurable adhesive according to the present invention has a weight reduction of 0 to 30% by weight when the thermoplastic resin film to be bonded to the polyvinyl alcohol polarizer is immersed at 23 ° C. for 2 days. Preferably it can be 25 wt% or less. The photocurable adhesive according to the present invention can have a small dissolving power with respect to, for example, a stretched acetylcellulose-based resin film. Examples of the stretched acetylcellulose-based resin film include an acetylcellulose-based resin film having an in-plane retardation value at a wavelength of 590 nm of 10 nm or more, and further 50 nm or more.

The weight reduction when the thermoplastic resin film is immersed in the photo-curable adhesive is determined as follows. That is, first, a thermoplastic resin film is cut into an appropriate size, and its weight is determined. Next, the cut thermoplastic resin film is prepared in a liquid state, immersed in a photocurable adhesive maintained at a temperature of 23 ° C., left to stand for 2 days, taken out, and the adhesive adhered to the surface is removed. After wiping, determine its weight. And the following formula:
Weight reduction (%) = {(film weight before immersion−film weight after immersion) / film weight before immersion} × 100
From this, the weight reduction after immersion is determined.

<Polarizing plate>
The polarizing plate according to the present invention includes a polyvinyl alcohol polarizer and a thermoplastic resin film bonded to at least one surface thereof via an adhesive layer that is a cured product of the photocurable adhesive. It is a waste.

  In addition, the adhesive layer cured in the polarizing plate according to the present invention can have a high storage elastic modulus, and can have excellent adhesion between the polarizer and the thermoplastic resin film. In the polarizing plate according to the present invention, the storage elastic modulus of the adhesive layer may be, for example, 1000 MPa or more, further 1500 MPa or more at 80 ° C. In the polarizing plate according to the present invention, the peel strength between the polarizer and the thermoplastic resin film can be 0.5 N / 25 mm or more, 0.6 N / 25 mm or more, and further 0.7 N / 25 mm or more. Still further, it can be 1.0 N / 25 mm or more. The storage elastic modulus at 80 ° C. of the adhesive layer and the peel strength between the polarizer and the thermoplastic resin film are measured according to the description in the section of Examples described later.

(1) Polyvinyl alcohol-type polarizer A polyvinyl alcohol-type polarizer is comprised with the polyvinyl-alcohol-type resin film by which the dichroic pigment | dye was adsorption-oriented. The polyvinyl alcohol resin constituting the polarizer can be obtained by saponifying a polyvinyl acetate resin. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, as well as copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, and unsaturated sulfonic acids. The degree of saponification of the polyvinyl alcohol resin is usually 85 to 100 mol%, preferably 98 to 100 mol%. The polyvinyl alcohol-based resin may be further modified, and for example, polyvinyl formal and polyvinyl acetal modified with aldehydes may be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually 1000 to 10,000, preferably 1500 to 5000.

  The polarizer is a step of uniaxially stretching the polyvinyl alcohol-based resin film, a step of dyeing the polyvinyl alcohol-based resin film with a dichroic dye, and adsorbing the dichroic dye, a polyvinyl on which the dichroic dye is adsorbed It is manufactured through a process of treating an alcohol-based resin film with an aqueous boric acid solution.

  Uniaxial stretching may be performed before dyeing with a dichroic dye, may be performed simultaneously with dyeing with a dichroic dye, or may be performed after dyeing with a dichroic dye. When uniaxial stretching is performed after dyeing with a dichroic dye, this uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. It is also possible to perform uniaxial stretching in these plural stages. The method of uniaxial stretching is not particularly limited, and uniaxial stretching may be performed between rolls having different peripheral speeds, or uniaxial stretching may be performed using a hot roll. Moreover, the dry-type extending | stretching which extends | stretches in air | atmosphere may be sufficient, and the wet extending | stretching which extends | stretches in the state swollen with the solvent may be sufficient. The draw ratio is usually about 4 to 8 times.

  The dichroic dye can be adsorbed by immersing the polyvinyl alcohol-based resin film in an aqueous solution containing the dichroic dye. As the dichroic dye, iodine or a dichroic organic dye is used.

  When iodine is used as the dichroic dye, a method of dyeing a polyvinyl alcohol resin film by dipping in an aqueous solution containing iodine and potassium iodide is usually employed. The content of iodine in this aqueous solution is usually about 0.01 to 0.5 parts by weight per 100 parts by weight of water, and the content of potassium iodide is usually about 0.5 to 10 parts by weight per 100 parts by weight of water. It is. The temperature of this aqueous solution is usually about 20 to 40 ° C., and the immersion time (dyeing time) in this aqueous solution is usually about 30 to 300 seconds.

On the other hand, when a dichroic organic dye is used as the dichroic dye, a method of immersing and dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic organic dye is usually employed. The content of the dichroic organic dye in this aqueous solution is usually about 1 × 10 ⁻³ to 1 × 10 ⁻² parts by weight per 100 parts by weight of water. This aqueous solution may contain an inorganic salt such as sodium sulfate. The temperature of this aqueous solution is usually about 20 to 80 ° C., and the immersion time (dyeing time) in this aqueous solution is usually about 30 to 300 seconds.

  The boric acid treatment after dyeing is performed by immersing the dyed polyvinyl alcohol-based resin film in an aqueous boric acid solution. The boric acid content in the boric acid aqueous solution is usually about 2 to 15 parts by weight, preferably about 5 to 12 parts by weight per 100 parts by weight of water. When iodine is used as the dichroic dye, the boric acid aqueous solution preferably contains potassium iodide. The content of potassium iodide in the boric acid aqueous solution is usually about 2 to 20 parts by weight, preferably 5 to 15 parts by weight per 100 parts by weight of water. The immersion time in the boric acid aqueous solution is usually about 100 to 1200 seconds, preferably about 150 to 600 seconds, and more preferably about 200 to 400 seconds. The temperature of the boric acid aqueous solution is usually 50 ° C. or higher, preferably 50 to 85 ° C.

  The polyvinyl alcohol resin film after the boric acid treatment is usually washed with water. The water washing treatment can be performed, for example, by immersing a boric acid-treated polyvinyl alcohol resin film in water. After washing with water, a drying process is performed to obtain a polarizer. The temperature of water in the water washing treatment is usually about 5 to 40 ° C., and the immersion time is usually about 2 to 120 seconds. The drying process performed after that can be normally performed using a hot air dryer or a far-infrared heater. The drying temperature is usually 40 to 100 ° C. Moreover, the time of a drying process is about 120 to 600 seconds normally. The thickness of the polyvinyl alcohol-based polarizer can be about 2 to 50 μm (for example, 5 to 20 μm).

(2) Thermoplastic resin film Thermoplastic resin film is more permeable to moisture than acetylcellulose-based resin films including triacetylcellulose, which has been most widely used as a protective film for polarizers, and triacetylcellulose. It can be composed of a low transparent resin film. Moisture permeability of triacetyl cellulose is approximately 400g / m ² / 24hr approximately. The moisture permeability of the thermoplastic resin film is measured at a temperature of 40 ° C. and a relative humidity of 90% by the cup method defined in JIS Z 0208.

  The thermoplastic resin film may be an unstretched film or a uniaxially or biaxially stretched film. The thermoplastic resin film can be, for example, a protective film for a polarizer, or an optical compensation film such as a retardation film.

In one preferable embodiment, the thermoplastic resin film bonded to at least one surface of the polarizer is composed of an acetylcellulose-based resin. This acetylcellulose-based resin film may contain an ultraviolet absorber. In other preferred embodiments, the thermoplastic resin film to be stuck on at least one surface of the polarizer is less thermoplastic resin resin film than triacetylcellulose moisture permeability, for example, moisture permeability 300g / m ² / 24hr It is comprised with the following thermoplastic resin resin films. Examples of the resin constituting such a low moisture permeability thermoplastic resin film include an amorphous polyolefin resin, a polyester resin, a (meth) acrylic resin, a polycarbonate resin, and a chain polyolefin resin. it can. Among these, amorphous polyolefin resin, polyester resin, and chain polyolefin resin are preferably used. In still another preferred embodiment, a first thermoplastic resin film made of an acetylcellulose-based resin is provided on one surface of a polarizer via an adhesive layer that is a cured product of the photocurable adhesive according to the present invention. A second thermoplastic made of a transparent resin having a lower moisture permeability as described above through an adhesive layer which is a cured product of the photocurable adhesive according to the present invention, which is bonded to the other surface of the polarizer. A resin film is bonded.

  An acetyl cellulose resin is a resin in which at least a part of hydroxyl groups in cellulose is esterified, and a mixed ester in which part is acetated and partly esterified with another acid. Good. Specific examples of the acetyl cellulose resin include triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, and cellulose acetate butyrate.

  An amorphous polyolefin-based resin is a polymer having a polymerized unit of cyclic olefin, such as norbornene, tetracyclododecene (also known as dimethanooctahydronaphthalene), or a compound having a substituent bonded thereto. It may be a copolymer obtained by copolymerizing a chain olefin and / or an aromatic vinyl compound. In the case of a homopolymer of a cyclic olefin or a copolymer of two or more kinds of cyclic olefins, a double bond remains by ring-opening polymerization, and hydrogenated ones are generally used as amorphous polyolefin-based resins. Used. Among them, a thermoplastic norbornene resin is representative.

  The polyester resin is a polymer obtained by condensation polymerization of a dibasic acid and a dihydric alcohol, and polyethylene terephthalate is representative. (Meth) acrylic resin is a polymer mainly composed of methyl methacrylate. In addition to methyl methacrylate homopolymer, methyl methacrylate and other monomers (such as methyl acrylate) It may be a copolymer with (meth) acrylic monomers such as acrylic acid esters and aromatic vinyl compounds. In the present specification, “(meth) acryl” means at least one selected from acryl and methacryl.

  The polycarbonate resin is a polymer having a carbonate bond (—O—CO—O—) in the main chain, and is typically obtained by condensation polymerization of bisphenol A and phosgene. The chain polyolefin-based resin is a polymer mainly containing a chain olefin such as ethylene or propylene, and can be a homopolymer or a copolymer. Among them, a propylene homopolymer and a copolymer in which a small amount of ethylene is copolymerized with propylene are representative.

  The thermoplastic resin film may contain a known additive as required. Known additives include, for example, lubricants, antiblocking agents, heat stabilizers, ultraviolet absorbers, antioxidants, antistatic agents, light resistance agents, impact resistance improvers, surfactants, and the like. Examples of ultraviolet absorbers include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, nickel complex compounds, and the like. However, since transparency is required for the thermoplastic resin film laminated on the polarizer, the amount of these additives is preferably kept to a minimum.

  A film provided with an optical compensation function can also be used as the thermoplastic resin film. An acetylcellulose-based resin film can also be used. Examples of such an optical compensation film include a retardation film in which a compound having a retardation adjusting function is contained in an acetyl cellulose resin, a retardation film in which a compound having a retardation adjusting function is coated on the surface of an acetyl cellulose resin, acetyl Examples thereof include a retardation film obtained by stretching a cellulose resin uniaxially or biaxially. A film made of another thermoplastic resin may be used as the optical compensation film.

  The thickness of the thermoplastic resin film is usually in the range of about 5 to 200 μm, preferably 10 to 120 μm, more preferably 10 to 100 μm. The thermoplastic resin film has various surface treatment layers (coating layers) such as a hard coat layer, antireflection layer, antiglare layer, antistatic layer, and light diffusion layer on the surface opposite to the adhesive surface to the polarizer. You may have.

(3) Manufacture of a polarizing plate A polarizing plate is obtained by adhere | attaching a thermoplastic resin film on the at least one surface of a polarizer using the above-mentioned photocurable adhesive agent. Specifically, after the above-mentioned photocurable adhesive coating layer is formed on the adhesive surface of the polarizer and / or thermoplastic resin film, and the polarizer and the thermoplastic resin film are bonded via the coating layer. Then, the coating layer of the uncured photocurable adhesive is cured by irradiation with active energy rays, and the thermoplastic resin film is fixed on the polarizer. Various coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used for forming the photocurable adhesive coating layer. It is also possible to employ a method in which an adhesive is cast between the polarizer and the thermoplastic resin film while continuously supplying the adhesive surface of the polarizer and the thermoplastic resin film inside.

  Depending on the coating method of the photocurable adhesive, the viscosity of the photocurable adhesive may be adjusted using a solvent. As the solvent, a solvent that dissolves the photocurable adhesive satisfactorily without degrading the optical performance of the polarizer is used, but there is no particular limitation on the type thereof. For example, organic solvents such as hydrocarbons typified by toluene and esters typified by ethyl acetate can be used. However, when a solvent is contained, it is necessary to provide a drying step for removing the solvent before irradiation with active energy rays. Therefore, it is preferable not to use the solvent as much as possible.

  The thickness of the adhesive layer after curing can be arbitrarily set depending on the characteristic design of the polarizing plate, but is preferably smaller from the viewpoint of reducing the cost of the adhesive material. Generally, it is 0.01-20 micrometers, Preferably, it is 0.1-10 micrometers, More preferably, it is 0.5-5 micrometers. If the thickness of the adhesive layer is reduced, bubbles are likely to be mixed into the adhesive layer, and adhesion and durability are likely to deteriorate. However, according to the photocurable adhesive of the present invention, this can be effectively suppressed. Can do. When the adhesive layer is excessively thick, the reaction rate of the adhesive is lowered, and the wet heat resistance of the polarizing plate tends to deteriorate.

  When the thermoplastic resin film is bonded only to one side of the polarizer, for example, the adhesive layer for bonding to another optical member such as a liquid crystal cell is directly provided on the other side of the polarizer. You can also. On the other hand, when a thermoplastic resin film is bonded to both surfaces of the polarizer, these thermoplastic resin films may be made of the same kind of resin or different kinds of resins. The thermoplastic resin film bonded to one surface of the polarizer is bonded using the above-described photocurable adhesive according to the present invention, but the thermoplastic resin film bonded to the other surface of the polarizer is They may be bonded using the photo-curable adhesive according to the present invention, or may be bonded using other adhesives.

  Prior to adhesion of the thermoplastic resin film to the polarizer, the adhesive surface of the thermoplastic resin film and / or polarizer can be easily subjected to saponification treatment, corona treatment, plasma treatment, primer treatment, anchor coating treatment, flame treatment, etc. An adhesion treatment may be performed.

  The light source used for irradiating the active energy ray to the photocurable adhesive coating layer may be any one that can generate ultraviolet rays, electron beams, X-rays, and the like. In particular, for example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excitation mercury lamp, a metal halide lamp or the like having a light emission distribution at a wavelength of 400 nm or less is preferably used.

The irradiation intensity of the active energy ray to the photocurable adhesive is not particularly limited, but the irradiation intensity in the wavelength region effective for activating the photocationic polymerization initiator (B) is 0.1 to 3000 mW / cm ^2. preferable. If it is less than 0.1 mW / cm ² , the reaction time becomes too long, and if it exceeds 3000 mW / cm ² , the photocurable adhesive is caused by heat radiated from the lamp and heat generated during polymerization of the photocurable adhesive. May cause yellowing and deterioration of the polarizer.

The light irradiation time to the photocurable adhesive is not particularly limited, but is preferably set so that the integrated light amount expressed as the product of the irradiation intensity and the irradiation time is 10 to 5000 mJ / cm ² . If it is less than 10 mJ / cm ² , the generation of the active species derived from the photocationic polymerization initiator (B) is not sufficient, and the resulting adhesive layer may not be sufficiently cured, while the accumulated light quantity is If it exceeds 5000 mJ / cm ² , the irradiation time becomes very long, which is disadvantageous for improving productivity.

  When the thermoplastic resin film is bonded to both sides of the polarizer, the irradiation of active energy rays may be performed from either side of the thermoplastic resin film, for example, one thermoplastic resin film contains an ultraviolet absorber, When the other thermoplastic resin film does not contain an ultraviolet absorber, irradiating active energy rays from the thermoplastic resin film side not containing an ultraviolet absorber effectively utilizes the irradiated active energy rays, It is preferable for increasing the curing rate.

  The polarizing plate obtained by curing the photocurable adhesive has a peel strength between the polarizer and the thermoplastic resin film of 0.5 N / 25 mm or more as measured in accordance with the description in Examples below. Is preferably 0.6 N / 25 mm or more, more preferably 0.7 N / 25 mm or more. When the peel strength is less than 0.5 N / 25 mm, peeling may occur between the polarizer and the adhesive layer when the polarizing plate is cut.

<Laminated optical member and liquid crystal display device>
The polarizing plate of the present invention can be made into a laminated optical member by laminating optical layers having optical functions other than the polarizing plate. Typically, a laminated optical member is obtained by laminating and attaching an optical layer on a thermoplastic resin film of a polarizing plate via an adhesive or a pressure-sensitive adhesive. In addition, for example, on one surface of a polarizer, The thermoplastic resin film can be adhered via the photocurable adhesive according to the present invention, and the optical layer can be laminated and adhered to the other surface of the polarizer via an adhesive or a pressure-sensitive adhesive. In the latter case, if the photocurable adhesive according to the present invention is used as an adhesive for adhering the polarizer and the optical layer, the optical layer can simultaneously be a thermoplastic resin film. Two or more optical layers may be laminated on the polarizing plate.

  As an optical layer laminated on the polarizing plate, a reflective layer, a transflective layer, a light laminated on the side opposite to the liquid crystal cell in the polarizing plate with respect to the polarizing plate arranged on the back side of the liquid crystal cell. Examples include a diffusion layer, a light collector, and a brightness enhancement film. Moreover, with respect to the polarizing plate arranged on the front side of the liquid crystal cell and / or the polarizing plate arranged on the back side of the liquid crystal cell, a retardation plate (retardation film) laminated on the liquid crystal cell side in the polarizing plate. Etc.

  The reflective layer, the semi-transmissive reflective layer, and the light diffusing layer are provided to form laminated optical members that are a reflective polarizing plate, a semi-transmissive reflective polarizing plate, and a diffusing polarizing plate, respectively. The reflective polarizing plate is used in a liquid crystal display device of a type that reflects and displays incident light from the viewing side, and a light source such as a backlight can be omitted, so that the liquid crystal display device can be easily thinned. Further, the transflective polarizing plate is used in a liquid crystal display device of a type that displays in a bright place as a reflection type and in a dark place with light from a backlight. The reflective polarizing plate can be produced, for example, by forming a reflective layer by attaching a foil or a vapor deposition film made of a metal such as aluminum to a thermoplastic resin film on a polarizer. The transflective polarizing plate can be produced by using the above reflective layer as a half mirror, or by adhering a reflective plate exhibiting optical transparency by containing a pearl pigment or the like to the polarizing plate. On the other hand, the diffusion type polarizing plate uses various methods such as a method of performing a mat treatment on a thermoplastic resin film on the polarizing plate, a method of applying a resin containing fine particles, and a method of adhering a film containing fine particles. It can be produced by forming a fine relief structure on the surface.

  Further, the laminated optical member can be a polarizing plate for both reflection and diffusion. The polarizing plate for both reflection and diffusion can be produced, for example, by providing a reflective layer reflecting the concavo-convex structure on the fine concavo-convex structure surface of the diffusing polarizing plate. The reflective layer having a fine concavo-convex structure has advantages such that incident light is diffused by irregular reflection, directivity and glare can be prevented, and unevenness in brightness and darkness can be suppressed. In addition, since the resin layer or film containing fine particles diffuses incident light and its reflected light, it also has an advantage that unevenness in brightness and darkness can be suppressed. The reflective layer reflecting the surface fine concavo-convex structure can be formed by directly attaching a metal to the surface of the fine concavo-convex structure by a method such as vapor deposition such as vacuum deposition, ion plating, sputtering, or plating. The fine particles to be blended to form the surface fine concavo-convex structure are, for example, silica, aluminum oxide, titanium oxide, zirconia, tin oxide, indium oxide, cadmium oxide, and antimony oxide having an average particle diameter of 0.1 to 30 μm. Inorganic fine particles, organic fine particles such as a crosslinked or non-crosslinked polymer, and the like.

  The condensing plate is used for the purpose of optical path control and can be formed as a prism array sheet, a lens array sheet, a dot-attached sheet, or the like.

  The brightness enhancement film is used for the purpose of improving the brightness in a liquid crystal display device, and a specific example thereof is that a plurality of thin film films having different refractive index anisotropies are laminated to produce anisotropy in reflectance. Reflection-type polarized light separation sheet designed in such a manner, a cholesteric liquid crystal polymer alignment film and a circularly polarized light separation sheet in which the alignment liquid crystal layer is supported on a film substrate.

  The retardation plate (retardation film) is used for the purpose of compensation of retardation by a liquid crystal cell. Specific examples thereof include a birefringent film made of a stretched film of various plastics, a film in which a discotic liquid crystal or a nematic liquid crystal is oriented and fixed, and a film substrate on which the liquid crystal layer is formed. When the liquid crystal layer is formed on the film substrate, an acetylcellulose-based resin film such as triacetylcellulose is preferably used as the film substrate.

  Examples of the plastic forming the birefringent film include amorphous polyolefin resin, polycarbonate resin, (meth) acrylic resin, chain polyolefin resin such as polypropylene, polyvinyl alcohol, polystyrene, polyarylate, polyamide. Etc. The stretched film can be processed by an appropriate method such as uniaxial or biaxial. Two or more retardation plates may be used in combination for the purpose of controlling optical characteristics such as broadening the bandwidth.

  Since the optical compensation can be effectively performed when applied to a liquid crystal display device, the laminated optical member preferably includes a retardation plate (retardation film) as an optical layer other than the polarizing plate. The retardation value (in-plane and thickness direction) of the retardation plate is adjusted according to the applied liquid crystal cell.

  A laminated optical member can be made into a laminated body of two layers or three or more layers by combining a polarizing plate and one layer or two or more layers selected according to the purpose of use from the various optical layers described above. In that case, the various optical layers forming the laminated optical member are integrated with the polarizing plate using an adhesive or a pressure-sensitive adhesive (also called a pressure-sensitive adhesive). If an agent layer and an adhesive layer are formed favorably, there will be no limitation in particular. It is preferable to use a pressure-sensitive adhesive from the viewpoint of simplicity of bonding work and prevention of optical distortion. As the pressure-sensitive adhesive, those having (meth) acrylic polymer, silicone polymer, polyester, polyurethane, polyether or the like as a base polymer can be used. Above all, like (meth) acrylic pressure-sensitive adhesive, it has excellent optical transparency, retains moderate wettability and cohesion, and has excellent adhesion to the substrate, and also has weather resistance, heat resistance, etc. It is preferable to select and use one that does not cause problems such as floating or peeling under the conditions of heating or humidification. In (meth) acrylic pressure-sensitive adhesives, alkyl esters of (meth) acrylic acid having an alkyl group having 20 or less carbon atoms such as methyl group, ethyl group, butyl group, (meth) acrylic acid and (meth) acrylic A functional group-containing (meth) acrylic monomer such as hydroxyethyl acid is blended so that the glass transition temperature is preferably 25 ° C. or lower, more preferably 0 ° C. or lower. ) Acrylic copolymers are useful as the base polymer.

  The pressure-sensitive adhesive layer is formed on the polarizing plate by, for example, dissolving or dispersing the pressure-sensitive adhesive composition in an organic solvent such as toluene or ethyl acetate to prepare a 10 to 40% by weight solution, which is directly on the polarizing plate. It can be carried out by a coating method, a method in which an adhesive layer is previously formed on a separate film (peeling film), and transferred onto a polarizing plate. Although the thickness of an adhesive layer is determined according to the adhesive force etc., the range of about 1-50 micrometers is suitable.

  If necessary, the pressure-sensitive adhesive layer contains fillers made of glass fibers, glass beads, resin beads, metal powder and other inorganic powders, pigments and colorants, antioxidants, UV absorbers, etc. Also good. Examples of ultraviolet absorbers include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, nickel complex compounds, and the like.

  The liquid crystal display device includes a liquid crystal cell and the polarizing plate or the laminated optical member disposed on at least one surface thereof. The polarizing plate and the laminated optical member can be laminated on one side or both sides of the liquid crystal cell via an adhesive layer. Each of the polarizing plate and the laminated optical member may be a polarizing plate with a pressure-sensitive adhesive layer and a laminated optical member in which an adhesive layer for bonding to a liquid crystal cell is laminated on the outer surface thereof. The liquid crystal cell to be used is arbitrary. For example, a liquid crystal display device using various liquid crystal cells such as an active matrix driving type typified by a thin film transistor type and a simple matrix driving type typified by a super twisted nematic type. Can be formed.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated further more concretely, this invention is not limited by these examples. Hereinafter, the part and% showing usage-amount thru | or content are a basis of weight unless there is particular notice. The photocationic curable component (A), the photocationic polymerization initiator (B), and the photosensitizer / photosensitizer (C) used in the following examples are as follows. Display with a symbol. In Table 2, the photocationic curable component (A), the photocationic polymerization initiator (B), and the photosensitizer / photosensitizer (C) are represented by (A), (B), ( C).

[Photocationic curable component (A)]
(A1) 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate [in the above formula (II), R ¹ = R ² = H, X = —C (═O) —O—CH ₂ —. Compound〕,
(A2) Neopentyl glycol diglycidyl ether [a compound in which Z = —CH ₂ C (CH ₃ ) ₂ CH ₂ — in the above formula (III)],
(A3) Trade name “ADEKA RESIN EP-4088S” manufactured by ADEKA CORPORATION [In the above formula (I), V is a divalent group obtained by removing two OH from tricyclodecane dimethanol, and n is 2. Compound〕,
(A4) Oxetane compound manufactured by Toagosei Co., Ltd., trade name “OXT-221”,
(A5) Naphthalene type epoxy resin manufactured by DIC, trade name “HP-4032D”,
(A6) Isosorbite diglycidyl ether.

[Photocationic polymerization initiator (B)]
(B1) A 50% solution of propylene carbonate in a mixture of a compound represented by the following formula (V) and a compound represented by the following formula (VI).

[Photosensitizer / photosensitizer (C)]
(C1) 1,4-diethoxynaphthalene,
(C2) 9,10-Dibutoxyanthracene.

<Examples 1-15, Comparative Examples 1-3>
(1) Preparation of photocurable adhesive Each component shown in Table 2 and Table 3 was mixed at the blending ratio shown in Table 2 and Table 3, and then defoamed to obtain a photocurable adhesive (liquid). Prepared. The unit of the blending amount of each component in Table 2 and Table 3 is “part”. The cationic photopolymerization initiator (B) is a 50% propylene carbonate solution, and Tables 2 and 3 show blending amounts based on the solid content.

(2) Measurement of viscosity of photocurable adhesive at 25 ° C. For each photocurable adhesive (adhesive solution) prepared in (1) above, an E-type viscometer “TVE” manufactured by Toki Sangyo Co., Ltd. -25L ", the viscosity (mPa · s) at a temperature of 25 ° C was measured. The results are shown in Tables 4 and 5.

(3) Measurement of moisture at 25 ° C. of photocurable adhesive About each photocurable adhesive (adhesive solution) prepared in (1) above, a moisture meter “AQV-2100ST” manufactured by Hiranuma Sangyo Co., Ltd. Was used to measure moisture at a temperature of 25 ° C. (parts by weight relative to 100 parts by weight of the photocationic curable component (A)). The results are shown in Tables 4 and 5.

(4) Measurement of ability (solving power) of photocurable adhesive for dissolving thermoplastic resin film Retardation film made of triacetyl cellulose (TAC) having a thickness of 40 μm [trade name “N” manufactured by Konica Minolta Opto Co., Ltd. -TAC KC4FR-1 "]. This retardation film is bonded to a polyvinyl alcohol polarizer as a thermoplastic resin film having an optical compensation function, and is used for producing a polarizing plate. After this retardation film was cut into a size of 10 mm × 40 mm, it was immersed in 20 g of each photocurable adhesive (adhesive liquid) prepared above at a temperature of 23 ° C. for 2 days. Two days later, the retardation film was taken out, the adhesive liquid adhering to the retardation film was wiped off with Ben cotton, and the weight was measured. From the film weight before immersion in the adhesive liquid and the film weight after immersion, the following formula:
Weight reduction (%) = {(film weight before immersion−film weight after immersion) / film weight before immersion} × 100
Was used to determine the weight loss of the film, and this was taken as the dissolving power. The results are shown in Tables 4 and 5. The greater the weight loss, the higher the dissolving power.

(5) Measurement of storage elastic modulus of adhesive layer at 80 ° C. About each photocurable adhesive (adhesive solution) prepared in (1) above, untreated polyethylene terephthalate film (trade name, manufactured by Toyobo Co., Ltd.) “Soft Shine”) was applied with a bar coater # 20 and irradiated with ultraviolet rays using an ultraviolet irradiation device with a belt conveyor (metal halide lamp) so that the integrated light amount was 3000 mJ / cm ² (UVA). After 24 hours, the cured adhesive (cured adhesive layer) was peeled from the polyethylene terephthalate film to obtain a cured film. The viscoelasticity measuring device “DMA7100” manufactured by Hitachi High-Tech Science Co., Ltd. is used to hold the obtained cured film so that its long side is in the tensile direction, and the frequency of tension and contraction is set at a spacing of 2 cm. The storage elastic modulus (MPa) at 80 ° C. was measured by setting 10 Hz and the temperature rising rate to 3 ° C./min. The results are shown in Tables 4 and 5.

(6) Production of Polarizing Plate A retardation film made of triacetylcellulose (TAC) having a thickness of 40 μm [trade name “N-TAC KC4FR-1” manufactured by Konica Minolta Opto Co., Ltd.]] (in Tables 4 and 5, Abbreviated as “retardation TAC”), an unstretched thermoplastic resin film made of triacetylcellulose (TAC) having a thickness of 80 μm containing an ultraviolet absorber (abbreviated as “TAC” in Tables 4 and 5). Or a 50 μm-thick retardation film (trade name “ZEONOR” manufactured by Nippon Zeon Co., Ltd.) (abbreviated as “COP” in Tables 4 and 5) made of norbornene resin (cyclic polyolefin resin). One side was subjected to corona treatment, and the photocurable adhesive (adhesive solution) prepared in the above (1) was applied to these corona-treated surfaces using an adhesive coating apparatus. A polyvinyl alcohol-iodine polarizer having a thickness of 25 μm was laminated on the coating layer of this adhesive, and bonded using a nip roll (pressing pressure: 1.5 MPa). Next, irradiate with ultraviolet rays (UVA) whose total integrated light amount (integrated amount of light irradiation intensity in the wavelength region of wavelength 320 to 400 nm) is about 350 mJ / cm ² (measurement value: measured by UV Power Puck II manufactured by FusionUV). Thus, the adhesive layer was cured to obtain a polarizing plate in which a thermoplastic resin film was bonded to one side of the polarizer. The thickness of the adhesive layer was set to 2.8 μm after curing.

(7) 180 degree peeling test of polarizing plate After cutting the polarizing plate prepared in the above (6) into a size of 200 mm length × 25 mm width, an acrylic pressure-sensitive adhesive layer is provided on the thermoplastic resin film side, It was set as the test piece for measuring the peeling strength between a thermoplastic resin film and a polarizer. A test piece is attached to a glass plate using the pressure-sensitive adhesive layer, a cutter blade is inserted between the polarizer and the thermoplastic resin film, and 30 mm is peeled off from the end in the length direction. I grabbed at the grip. With respect to the test piece in this state, in accordance with JIS K 6854-2: 1999 “Adhesive—Peeling adhesive strength test method—Part 2: 180 degree peeling” in an atmosphere having a temperature of 23 ° C. and a relative humidity of 55%. Then, a 180 degree peel test was performed at a grip moving speed of 300 mm / min, and an average peel force over a length of 170 mm excluding 30 mm of the grip part was obtained, and this was defined as a peel strength between the thermoplastic resin film and the polarizer. . The peel strength was measured for each of the above three types of thermoplastic resin films. The measurement is performed 24 hours after the polarizing plate is produced. The results are shown in Tables 4 and 5. In Tables 4 and 5, “non-peelable” means that the polarizer and the thermoplastic resin film could not be peeled under the above conditions.

Claims (10)

A polarizing plate comprising a polyvinyl alcohol polarizer and a thermoplastic resin film laminated on at least one surface of the polyvinyl alcohol polarizer via a cured product of a photocurable adhesive,
The photo-curable adhesive is
The main component is an epoxy compound containing no aromatic ring,
A photocationic curable component (A) and a photocationic polymerization initiator (B),
The photocationic curable component (A) has the following formula (I):

(In the formula, n represents an integer of 1 or more. V represents an n-valent group including a condensed ring composed of an alicyclic ring (excluding a condensed ring containing a hetero atom).)
The first epoxy compound (A1) represented by the following formula (II):

(In the formula, R ¹ and R ² each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and when the alkyl group has 3 or more carbon atoms, it may have an alicyclic structure. Often;
X is an oxygen atom, an alkanediyl group having 1 to 6 carbon atoms, or the following formulas (IIa) to (IId):

Represents a divalent group represented by any one of, here represents an alkanediyl group of Y ¹ to Y ⁴ are carbon atoms, respectively 20, in the case of 3 or more carbon atoms have an alicyclic structure May be;
a and b each represents an integer of 0 to 20. )
The polarizing plate containing the 2nd epoxy compound (A2) represented by these . A polarizing plate comprising a polyvinyl alcohol polarizer and a thermoplastic resin film laminated on at least one surface of the polyvinyl alcohol polarizer via a cured product of a photocurable adhesive,
The photo-curable adhesive is
The main component is an epoxy compound containing no aromatic ring,
A photocationic curable component (A) and a photocationic polymerization initiator (B),
The photocationic curable component (A) has the following formula (I):

(In the formula, n represents an integer of 1 or more. V represents an n-valent group including a condensed ring composed of an alicyclic ring, and the condensed ring is tricyclic.)
The first epoxy compound (A1) represented by the following formula (II):

(In the formula, R ¹ and R ² each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and when the alkyl group has 3 or more carbon atoms, it may have an alicyclic structure. Often;
X is an oxygen atom, an alkanediyl group having 1 to 6 carbon atoms, or the following formulas (IIa) to (IId):

Represents a divalent group represented by any one of, here represents an alkanediyl group of Y ¹ to Y ⁴ are carbon atoms, respectively 20, in the case of 3 or more carbon atoms have an alicyclic structure May be;
a and b each represents an integer of 0 to 20. )
The polarizing plate containing the 2nd epoxy compound (A2) represented by these . A polarizing plate comprising a polyvinyl alcohol polarizer and a thermoplastic resin film laminated on at least one surface of the polyvinyl alcohol polarizer via a cured product of a photocurable adhesive,
The photo-curable adhesive is
The main component is an epoxy compound containing no aromatic ring,
A photocationic curable component (A) and a photocationic polymerization initiator (B),
The photocationic curable component (A) has the following formula (I):

(In the formula, n represents an integer of 1 or more. V represents an n-valent group consisting of a condensed ring composed of an alicyclic ring and a linking group that connects the condensed ring and the glycidyloxy group in formula (I). Represents a group of
The first epoxy compound (A1) represented by the following formula (II):

(In the formula, R ¹ and R ² each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and when the alkyl group has 3 or more carbon atoms, it may have an alicyclic structure. Often;
X is an oxygen atom, an alkanediyl group having 1 to 6 carbon atoms, or the following formulas (IIa) to (IId):

Represents a divalent group represented by any one of, here represents an alkanediyl group of Y ¹ to Y ⁴ are carbon atoms, respectively 20, in the case of 3 or more carbon atoms have an alicyclic structure May be;
a and b each represents an integer of 0 to 20. )
The polarizing plate containing the 2nd epoxy compound (A2) represented by these .   The polarizing plate according to claim 3, wherein the linking group is a divalent aliphatic hydrocarbon group. The photocationic curable component (A) is based on the total amount thereof.
The first epoxy compound (A1) 5 to 85 wt%, and,
The polarizing plate of any one of Claims 1-4 which contains 15-85 weight% of said 2nd epoxy compounds (A2). Furthermore, the said photocationic curable component (A) is based on the whole quantity,
Formula (III) below:

(Wherein, Z is branched alkylene group having 3 to 8 carbon atoms, or the formula _{^{-C m H 2m -Z 1 -C n}} H 2n - represents a divalent group represented by wherein -Z ¹ - is , -O-, -CO-O- or -O-CO-, one of m and n represents an integer of 1 or more and the other represents an integer of 2 or more, and the sum of the two is 8 or less, and C _m One of H _2m and C _n H _2n represents a branched divalent saturated hydrocarbon group.)
The polarizing plate of any one of Claims 1-5 containing 1 to 70 weight% of 3rd epoxy compounds (A3) represented by these. Furthermore, with respect to 100 parts by weight of the photocationic curable component (A), the following formula (IVa):

Wherein R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an alkoxyalkyl group having 2 to 12 carbon atoms, and R 5 is a hydrogen atom or 1 to 6 carbon atoms. Represents an alkyl group of
And an anthracene compound represented by the following formula (IVb):

(In the formula, R ⁶ and R ⁷ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.)
The polarizing plate of any one of Claims 1-6 containing 0.1-5 weight part of 1 or more types of compounds selected from the group which consists of a naphthalene type compound represented by these.   The polarizing plate according to any one of claims 1 to 7, wherein the water content is more than 0 parts by weight and 4 parts by weight or less with respect to 100 parts by weight of the photocationic curable component (A).   The laminated optical member which consists of a laminated body of the polarizing plate of any one of Claims 1-8, and one or more other optical layers.   The laminated optical member according to claim 9, wherein the other optical layer includes a retardation plate.