TW202031847A - Photocurable adhesive, polarizing plate and laminated optical member - Google Patents

Abstract

An object of the present invention is to provide a photocurable adhesive composition which provides a polarizing plate having good adhesiveness without a protective film being peeled off from a polarizer at an end thereof even if the end is ground in the state of being cut into a predetermined size. The photocurable adhesive composition comprises the following (A) and (B). (A) a cationic photocurable component containing an epoxy compound represented by the following formula (I) (B) a cationic photopolymerization initiator [in the formula, R1 represents an alkyl group having 1 to 8 carbon atoms which may have at least one hydroxyl group, a group represented by the formula (Ia), or a group represented by the formula (Ib); X1, X2, X11 and X12 each independently represents a single bond or an alkanediyl group having 1 to 3 carbon atoms; Y1 and Y11 each independently represent a cyclic saturated hydrocarbon group having 3 to 8 carbon atoms, wherein the cyclic saturated hydrocarbon group having 3 to 8 carbon atoms may have a hydroxyl group, an alkylcarbonyloxy group having 2 to 8 carbon atoms, or an alkyl group having 1 to 6 carbon atoms].

Description

Light-curing adhesive, polarizing plate and laminated optical component

The present invention relates to a photocurable adhesive and a polarizing plate formed by bonding a protective film on a polarizer using the photocurable adhesive.

Patent Document 1 discloses an adhesive composition in which an epoxy compound containing no aromatic ring is used as the main component, and discloses that cationic polymerization caused by irradiation with active energy rays (specifically, irradiation with ultraviolet rays) causes The adhesive composition is cured to bond the polarizer and the protective film to the polarizer. In addition, Patent Document 2 discloses a photocurable adhesive containing an alicyclic epoxy compound, an epoxy compound without an alicyclic epoxy group, and a photocationic polymerization initiator. It also discloses a polarizing plate that uses the aforementioned photocurable adhesive to bond a polarizer and a protective film.

[Prior Technical Literature]

[Patent Literature]

[Patent Document 1] JP 2004-245925 A

[Patent Document 2] JP 2008-257199 A

However, the polarizing plate disclosed in Patent Document 1 and Patent Document 2 is cut into a predetermined size for application in a liquid crystal display. If the end is polished, a protective film (transparent resin film) will be on the end. The part is peeled from the polarizer.

The subject of the present invention is to provide a photocurable adhesive composition capable of providing a good adhesive force between the polarizer of the polarizing plate and the protective film (transparent resin film).

The present invention includes the following inventions.

[1] A photocurable adhesive composition containing the following (A) and (B):

(A) A photocationic curable component containing an epoxy compound represented by the following formula (I),

(B) Photocationic polymerization initiator;

[In formula (I), R ¹ represents an alkyl group having 1 to 8 carbon atoms which may have at least one hydroxyl group (the -CH ₂ -contained in the alkyl group may be replaced with an ester bond), and an ester which may be at least one Alkyl ester having a total of 2 to 8 carbon atoms, a hydroxyl group, a carboxyl group, a group represented by formula (Ia) or a group represented by formula (Ib) where the bond is interrupted

X ¹ , X ² , X ¹¹ and X ¹² each independently represent a single bond or an alkanediyl group having 1 to 3 carbon atoms.

Y ¹ and Y ¹¹ each independently represent a cyclopentanyl group or a cyclic saturated hydrocarbon group having 3 to 8 carbons. The cyclopentyl group or a cyclic saturated hydrocarbon group having 3 to 8 carbons may have a hydroxyl group and a carbon number of 2 to An alkylcarbonyloxy group of 8, an alkyl group having 1 to 6 carbons (the -CH ₂ -contained in the alkyl group may be replaced by -CO-)].

[2] The photocurable adhesive composition according to [1], wherein the photocurable adhesive composition contains (B) photocationic polymerization with respect to 100 parts by mass of the (A) photocationic curable component 1 to 10 parts by mass of the initiator;

The aforementioned photocationic curable components are based on their total amount and contain:

(A1) Epoxy compound represented by formula (I) 0.1 to 20% by mass

(A2) The alicyclic diepoxy compound represented by the following formula (II) is 50 to 90% by mass.

(式中，R²及R³係各自獨立地表示氫原子或碳數1至6的烷基，惟烷基為碳數3以上時亦可具有脂環結構；

(In the formula, R ² and R ³ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, but the alkyl group may have an alicyclic structure with a carbon number of 3 or more;

Z ¹ represents an oxygen atom, an alkanediyl group having 1 to 6 carbon atoms, or a divalent group represented by any of the following formulas (Ia) to (Id):

此處Y²至Y⁵係分別表示碳數1至20的烷二基，惟碳數3以上時亦可具有脂環結構；

Here, Y ² to Y ⁵ respectively represent an alkanediyl group having 1 to 20 carbon atoms, but may have an alicyclic structure when the carbon number is 3 or more;

a and b represent an integer from 0 to 20, respectively. )

[3] The photocurable adhesive composition as described in [1] or [2], which further contains (A3) 1 to 70% by mass of an aliphatic diglycidyl compound represented by the following formula (III);

(式中，Z²係表示碳數3至8的分枝伸烷基或式-C_mH_2m-Z¹-C_nH_2n-表示的2價基，此處-Z¹-係表示-O-、-CO-O-或-O-CO-，m及n其中一者係表示1以上的整數、另一者係表示2以上的整數，惟兩者的合計係8以下，且C_mH_2m及C_nH_2n其中一者係表示分枝的2價飽和烴基)。

(In the formula, Z ² represents a branched alkylene having 3 to 8 carbon atoms or a divalent group represented by the formula -C _m H _2m -Z ¹ -C _n H _2n -, where -Z ¹ -represents- O-, -CO-O- or -O-CO-, one of m and n represents an integer of 1 or more, the other represents an integer of 2 or more, but 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).

[4] The photocurable adhesive composition according to any one of [1] to [3], which further contains 0.1 to 5 parts by mass of an anthracene compound or formula selected from the following formula (IVa) One or more of the naphthalene compounds represented by (IVb);

(式中，R⁴及R⁵係各自獨立地表示氫原子、碳數1至6的烷基或碳數2至12的烷氧基烷基，R⁶係表示氫原子或碳數1至6的烷基)

(In the formula, R ⁴ and R ⁵ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbons or an alkoxyalkyl group having 2 to 12 carbons, and R ⁶ represents a hydrogen atom or a carbon number of 1 to 6 Alkyl)

(式中，R⁷及R⁸係各自獨立地表示碳數1至6的烷基)。

(In the formula, R ⁷ and R ⁸ each independently represent an alkyl group having 1 to 6 carbon atoms).

[5] A photocurable adhesive layer formed of the photocurable adhesive composition according to any one of [1] to [4].

[6] A laminated body formed by laminating a polarizer, an adhesive layer, and a transparent resin film in this order, wherein the adhesive layer is the photocurable adhesive layer described in [5].

[7] A laminated optical member formed of the laminated body described in [6] and the laminated body of other optical layers.

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

By using the photocurable adhesive of the present invention, the polarizing plate to which the polarizer and the transparent resin film are bonded can have good adhesion.

<Photocurable adhesive composition>

The photocurable adhesive composition system of the present invention contains the following (A) and (B):

(A) A photocationic curable component containing an epoxy compound represented by formula (I),

(B) Photocationic polymerization initiator.

<Photocationic curable ingredients>

The photocationic curable component contains at least the epoxy compound represented by formula (I).

[In the formula, R ¹ represents an alkyl group of 1 to 8 carbons which may have at least one hydroxyl group (the -CH ₂ -contained in the alkyl group may be replaced by an ester bond), which can be interrupted by at least one ester bond Alkyl ester having a total carbon number of 2 to 8, a hydroxyl group, a carboxyl group, a group represented by the following formula (Ia) or a group represented by the formula (Ib).

X ¹ , X ² , X ¹¹ and X ¹² each independently represent a single bond or an alkanediyl group having 1 to 3 carbon atoms.

Y ¹ and Y ¹¹ each independently represent a cyclopentanyl group or a cyclic saturated hydrocarbon group having 3 to 8 carbons. The cyclopentyl group or a cyclic saturated hydrocarbon group having 3 to 8 carbons may have a hydroxyl group and a carbon number of 2 to An alkylcarbonyloxy group of 8 or an alkyl group having 1 to 6 carbon atoms (the -CH ₂ -contained in the alkyl group may be replaced by -CO-). ]

The ester bond in the present invention refers to both -OCO- and -COO-.

The alkyl group having 1 to 8 carbon atoms represented by R ¹ includes methyl, ethyl, propyl, butyl, pentyl, and hexyl.

R ¹ represents a C 1-8 alkyl group of lines having a hydroxyl group include: hydroxymethyl, hydroxyethyl, hydroxypropyl and the like.

The alkyl esters with carbon numbers from 2 to 8 that can be interrupted by at least one ester bond represented by R ¹ include: methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, and other alkoxy groups with carbon numbers from 2 to 8 Alkylcarbonyl; methylcarbonyloxy, ethylcarbonyloxy, propylcarbonyloxy and other alkylcarbonyloxy groups having 2 to 8 carbon atoms.

Examples of the alkanediyl groups having 1 to 3 carbon atoms represented by X ¹ , X ² , X ¹¹ and X ¹² include methylene, ethylene, propane-1,3-diyl and the like.

The cyclic saturated hydrocarbon groups represented by Y ¹ and Y ¹¹ include cycloalkyl groups such as cyclic saturated hydrocarbon groups such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl.

Specifically, the epoxy compound represented by the formula (I) includes compounds of the formula (1) to (24).

The compound system represented by Formula (I) may contain 2 or more types.

From the point of view of the adhesion between the polarizer and the transparent resin film, the compound represented by formula (I) preferably has at least one hydroxyl group in the molecule, and R ¹ has at least one hydroxyl group and a carbon number of 1 to 8. The alkyl group is more preferable, and R ¹ is an alkyl group having at least one hydroxy group having 1 to 4 carbon atoms.

From the viewpoint of adjusting the viscosity of view, a compound is represented by formula (I) is R ¹ is interrupted by a total carbon number of at least one or more alkyl acrylate ester bond preferably 2 to 8, carbon atoms in R ¹ lines 2 The alkylcarbonyloxy group up to 8 is more preferable, and the alkylcarbonyloxy group having 3 to 8 carbon atoms is still more preferable.

The photocurable adhesive composition of the present invention contains: R ¹ is a compound represented by formula (I) (hereinafter also referred to as compound (I-1)) in which R ¹ is an alkyl group having at least one hydroxyl group and a carbon number of 1 to 8 A compound represented by formula (I) (hereinafter also referred to as compound (I-2)) in which R ¹ is an alkyl ester with a total carbon number of 2 to 8 that can be interrupted by at least one ester bond is preferred.

The content of the epoxy compound represented by the formula (I) is usually 0.1 to 20% by mass based on the total amount of the photocationic curable component (A). By containing 0.1% by mass or more of the epoxy compound represented by (I) in the photocationic curable component, the adhesion of the polarizing plate to which the polarizer and the transparent resin film are bonded can be made strong. On the other hand, when the content is increased to 20% by mass, the amount of the alicyclic diepoxy compound (A2) described below is relatively reduced, and the material strength of the cured film of the photocurable adhesive becomes lower. On the other hand, in durability tests such as heat and cold durability tests, the possibility of cracking of the polarizer becomes higher. Based on the total amount of the photocationic curable component, the content of the epoxy compound represented by formula (I) is preferably 0.5 to 10% by mass, more preferably 0.5 to 5% by mass, and 1 to 5% by mass Better yet.

In addition, when two or more types of compounds represented by formula (I) are contained, the sum of them should be within the above range.

When the compound (I-1) and the compound (I-2) are contained, it is preferable that the content of the compound (I-1) is greater than the content of the compound (I-2). When the content of compound (I-1) is set to W1 and the content of compound (I-2) is set to W2, the ratio (W1/W2) is preferably 1 or more, more preferably 1.5 or more, and 2 or more More preferably, it is preferably 10 or less, more preferably 8 or less, and more preferably 5 or less.

In addition, the photocationic curable component preferably further contains the alicyclic diepoxide compound represented by the formula (II) and the aliphatic diglycidyl compound represented by the following formula (III).

(In the formula, R ² and R ³ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, but the alkyl group may have an alicyclic structure with a carbon number of 3 or more;

Z ¹ represents an oxygen atom, an alkanediyl group having 1 to 6 carbon atoms, or a divalent group represented by any of the following formulas (IIa) to (IId):

此處，Y²至Y⁵係分別表示碳數1至20的烷二基，惟碳數3以上時亦可具有脂環結構；

Here, Y ² to Y ⁵ represent an alkanediyl group having 1 to 20 carbon atoms, but may have an alicyclic structure when the carbon number is 3 or more;

a and b represent an integer from 0 to 20, respectively. )

(In the formula, Z ² represents a branched alkylene group having 3 to 8 carbon atoms or a divalent group represented by the formula -C _m H _2m -Z ³ -C _n H _2n -, where -Z ³ -represents- O-, -CO-O- or -O-CO-, one of m and n represents an integer of 1 or more, the other represents an integer of 2 or more, but 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.)

In formula (II), R ² and R ³ are each independent hydrogen atom or an alkyl group having 1 to 6 carbons. However, when the carbon number of the alkyl group is 3 or more, it may be straight or branched. It may also have an alicyclic structure. The position of the cyclohexane ring bonded to X in the formula (I) is set to the 1-position (therefore, the positions of the epoxy groups in the two cyclohexane rings are both 3 and 4-positions). The group can also be bonded at any position from 1-position to 6-position. Examples of the alkyl group having an alicyclic structure include cycloalkyl groups such as cyclopentyl and cyclohexyl.

Z ¹ represents an oxygen atom, an alkanediyl group having 1 to 6 carbon atoms, or a divalent group represented by any one of the aforementioned formulas (IIa) to (IId). Here, the alkanediyl group includes the concepts of an alkylene group and an alkylene group, and the alkylene group may be a straight chain or a branched chain, and may have an alicyclic structure.

When Z ¹ is a divalent group represented by any one of the aforementioned formulas (IIa) to (IId), the linking groups Y ¹ , Y ² , Y ³ and Y ^{4 in} each formula are each alkane having 1 to 20 carbon atoms. When the carbon number of this alkanediyl group is 3 or more, it may be a straight chain or a branched chain, and it may have an alicyclic structure. Examples of the alkanediyl group having an alicyclic structure include cyclopentylene and cyclohexylene.

Z in the formula (II) is a compound with a divalent group represented by the formula (IIa), and examples thereof include 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate [formula ( II) (However, Z ¹ is a divalent group represented by formula (IIa) with a=0), R ² =R ³ =H compound], 3,4-epoxy-6-methylcyclohexylmethyl Group 3,4-epoxy-6-methylcyclohexane carboxylate [in formula (II) which has Z ¹ as above, R ² = 6-methyl, R ³ = 6-methyl Compound], 3,4-epoxy-1-methylcyclohexylmethyl 3,4-epoxy-1-methylcyclohexane carboxylate [in the same formula (II) with Z ¹ as above Where R ² =1-methyl, R ³ =1-methyl compound], 3,4-epoxy-3-methylcyclohexylmethyl 3,4-epoxy-3-methyl ring Hexane carboxylate [in the formula (II) having Z ¹ as described above, R ² =3-methyl, R ³ =3-methyl compound] and the like.

Z ¹ in formula (II) is a compound with a divalent group represented by formula (IIb), which is alkanediol and 3,4-epoxycyclohexanecarboxylic acid (the number of carbon atoms that can be bonded to the cyclohexane ring 1 to 6 alkyl) esters. Z ¹ in the formula (II) is a compound with a divalent group represented by the formula (IIc), which is aliphatic dicarboxylic acid and 3,4-epoxycyclohexyl methanol (the number of carbon atoms that can be bonded on the cyclohexane ring 1 to 6 alkyl) esters. In addition, Z ¹ in the formula (II) is a compound with a divalent group represented by the formula (IId), which is 3,4-epoxycyclohexylmethanol (the cyclohexane ring can be bonded with carbon number 1 to 6 Alkyl) ether body (b=0), or alkanediol or polyalkylene glycol and 3,4-epoxycyclohexylmethanol (the cyclohexane ring can be bonded to an alkane with 1 to 6 carbon atoms Group) etherate (b>0).

Z ² in the formula (III) is a branched alkylene compound, which is the diglycidyl ether of branched alkanediol. Specific examples thereof include: propylene glycol diglycidyl ether, 1,3-butanediol diglycidyl ether, 1,2-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 3-methyl- 1,5-pentanediol diglycidyl ether, 2-methyl-1,8-octanediol diglycidyl ether, 1,4-cyclohexanedimethanol, etc.

In addition, in the formula (III), Z ² is a compound of the divalent group represented by the above formula -C _m H _2m -Z ³ -C _n H _2n -, and Z ² is a branched alkylene group, which corresponds to the extension When the CC bond of the alkyl group is interrupted by -O-, -CO-O- or -O-CO-.

The content of the alicyclic diepoxy compound represented by formula (II) is usually 50 to 90% by mass relative to the total amount of the photocationic curable component. Since the photocationic curable component contains 50% by mass or more of the alicyclic diepoxy compound represented by formula (II), the storage elastic modulus after curing of the photocurable adhesive can be maintained at a high value. Improve the adhesion between the polarizer and the transparent resin film. On the other hand, if the content is increased to 90% by mass, the adhesive force between the polarizer and the transparent resin film becomes insufficient. On the premise that the adhesion between the polarizer and the transparent resin film and the storage elastic modulus after curing of the photocurable adhesive are set to better values, the formula (II) is expressed relative to the total amount of the photocationic curable component The content of the alicyclic diepoxide compound is preferably 50 to 90% by mass, and more preferably 50 to 80% by mass.

The content of the diglycidyl compound represented by the formula (III) is usually 1 to 69% by mass, preferably 5 to 50% by mass, and more preferably 5 to 40% by mass, relative to the total amount of photocationic curable components . When the content of the diglycidyl compound represented by the formula (III) in the photocationic curable component is more than 70% by mass, the curing becomes insufficient, and the adhesive force between the polarizer and the transparent resin film is reduced.

The photocationic curable component (A) may further contain other cationically polymerizable compounds. Specifically, a monofunctional aliphatic epoxy compound, an oxetane compound, a vinyl ether compound, etc. are mentioned.

Examples of monofunctional aliphatic epoxy compounds include: glycidyl ether of aliphatic alcohols, glycidyl esters of alkyl carboxylic acids, etc. Specific examples thereof include: allyl glycidyl ether, butane Glycidyl ether, second butyl phenyl glycidyl ether, 2-ethylhexyl glycidyl ether, mixed alkyl glycidyl ether with 12 and 13 carbon atoms, glycidyl ether of alcohol, monoglycidyl of aliphatic higher alcohol Ethers, glycidyl esters of higher fatty acids, etc.

The oxetane compound is a compound having an oxetanyl group, and specific examples thereof include: 3,7-bis(3-oxetanyl)-5-oxa-nonane, 1,4 -Bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene, 1,2-bis[(3-ethyl-3-oxetanylmethoxy) Methyl]ethane, 1,3-bis[(3-ethyl-3-oxetanylmethoxy)methyl]propane, ethylene glycol bis(3-ethyl-3-oxocycle Butyl methyl) ether, triethylene glycol bis(3-ethyl-3-oxetanyl methyl) ether, tetraethylene glycol bis(3-ethyl-3-oxetane) Methyl) ether, 1,4-bis(3-ethyl-3-oxetanylmethoxy)butane, 1,6-bis(3-ethyl-3-oxetane Methoxy)hexane, 3-ethyl-3-[(phenoxy)methyl]oxetane, 3-ethyl-3-(hexyloxymethyl)oxetane, 3-Ethyl-3-(2-ethylhexyloxymethyl)oxetane, 3-ethyl-3-(hydroxymethyl)oxetane, 3-ethyl-3-( Chloromethyl)oxetane and the like.

The vinyl ether compound includes aliphatic or alicyclic vinyl ether compounds, and specific examples thereof include n-pentyl vinyl ether, iso-pentyl vinyl ether, n-hexyl vinyl ether, n-octyl vinyl ether, 2 -Ethylhexyl vinyl ether, n-dodecyl vinyl ether, stearyl vinyl ether, oleyl vinyl ether and other vinyl ethers with 5 to 20 carbon alkyl or alkenyl alcohols; 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether and other hydroxyl-containing vinyl ethers; cyclohexyl vinyl ether, 2-methylcyclohexyl vinyl ether, cyclohexyl methyl vinyl ether, benzyl vinyl ether, etc. Vinyl ethers of monoalcohols with aliphatic or aromatic rings; glycerin monovinyl ether, 1,4-butanediol divinyl ether, 1,6-hexanediol divinyl ether, neopentyl glycol divinyl ether , Neopentyl erythritol divinyl ether, neopentyl Tetraol tetravinyl ether, trimethylolpropane divinyl ether, trimethylolpropane trivinyl ether, 1,4-dihydroxycyclohexane monovinyl ether, 1,4-dihydroxycyclohexane divinyl ether, Mono or polyvinyl ethers of polyols such as 1,4-dihydroxymethylcyclohexane monovinyl ether and 1,4-dihydroxymethylcyclohexane divinyl ether; diethylene glycol divinyl ether, triethyl Polyalkylene glycol monovinyl ether or polyalkylene glycol divinyl ether such as glycol divinyl ether and diethylene glycol monobutyl monovinyl ether; glycidyl vinyl ether, ethylene glycol vinyl ether methacrylate, etc. Other vinyl ethers, etc.

(Photocationic polymerization initiator)

The photocationic polymerization initiator is one that generates cationic species or Lewis acid by irradiation of active energy rays such as visible rays, ultraviolet rays, X-rays or electron rays, and initiates the polymerization reaction of the photocationic curable component. Since the photocationic polymerization initiator acts as a catalyst with light, even if it is mixed with the photocationic curable component, the storage stability and workability are excellent. As for compounds that generate cationic species or Lewis acids by irradiation of active energy rays, for example, aromatic diazonium salts; onium salts such as aromatic iodonium salts and aromatic sulfonium salts; iron-propane Diene complex (iron-allene complex) and so on.

Examples of the aromatic diazonium salt include the following compounds.

Benzene diazonium hexafluoroantimonate,

Benzene diazonium hexafluorophosphate,

Benzene diazonium hexafluoroborate and so on.

Examples of the aromatic iodonium salt include the following compounds.

Diphenyl iodonium tetra (pentafluorophenyl) borate,

Diphenyl iodonium hexafluorophosphate,

Diphenyl iodonium hexafluoroantimonate,

Bis (4-nonylphenyl) iodonium hexafluorophosphate and so on.

Examples of the aromatic sulfonium salt include the following compounds.

Triphenylsulfonium hexafluorophosphate,

Triphenylsulfonium hexafluoroantimonate,

Triphenylsulfonium (pentafluorophenyl) borate,

4,4'-Bis[diphenylaunyl]diphenylsulfide bishexafluorophosphate,

4,4'-Bis[bis(β-hydroxyethoxy)phenylaunyl] diphenyl sulfide bishexafluoroantimonate,

4,4'-Bis[bis(β-hydroxyethoxy)phenylaunyl] diphenyl sulfide bishexafluorophosphate,

7-[Bis(p-tolyl)ethanyl]-2-isopropylthioxanthone hexafluoroantimonate,

7-[Bis(p-tolyl)ethanyl]-2-isopropylthioxanthone 4(pentafluorophenyl) borate,

4-Phenylcarbonyl-4'-diphenylarunyl-diphenyl sulfide hexafluorophosphate,

4-(p-tert-butylphenylcarbonyl)-4'-diphenylarunyl-diphenyl sulfide hexafluoroantimonate,

4-(p-tert-butylphenylcarbonyl)-4'-bis(p-tolyl)ethanyl]-diphenyl sulfide (pentafluorophenyl) borate and the like.

Examples of the iron-allene complex system include the following compounds.

Xylene-cyclopentadienyl iron(II) hexafluoroantimonate,

Cumene-cyclopentadienyl iron (II) hexafluorophosphate,

Xylene-cyclopentadienyl iron (II) ginseng (trifluoromethylsulfonyl) methanate, etc.

These photocationic polymerization initiators may be used alone, or two or more of them may be mixed and used. Among these, especially because the aromatic sulfonium salt has a wavelength around 300nm The area also has ultraviolet absorbing properties, so it is excellent in curability, and it is more suitable for use because it can provide a cured product with good mechanical strength and adhesive strength.

The blending amount of the photocationic polymerization initiator is usually 1 to 10 parts by mass relative to 100 parts by mass of the entire photocationic curable component. By blending 1 part by mass or more of the photocationic polymerization initiator per 100 parts by mass of the photocationic curable component (A), the photocationic curable component can be fully cured, and the resulting polarizer can be given high mechanical strength and Then intensity. On the other hand, if the amount of the photocationic polymerization initiator is increased, the ionic substances in the cured product will increase and the moisture absorption of the cured product will increase, which may reduce the durability of the polarizing plate. The amount of the photocationic polymerization initiator per 100 parts by mass of the photocationic curable component is preferably 10 parts by mass or less. The compounding amount of the photocationic polymerization initiator per 100 parts by mass of the photocationic curable component is preferably 2 parts by mass or more, and more preferably 6 parts by mass or less.

(Reaction accelerator for photocurable adhesives)

The photocurable adhesive of the present invention may contain a photosensitizer and a photosensitizer in addition to a photocationic curable component containing the epoxy compound represented by formula (I) and a photocationic polymerization initiator. The photosensitizer exhibits maximum absorption at a wavelength longer than the maximum absorption wavelength displayed by the photocationic polymerization initiator, and is a compound that promotes the polymerization initiation reaction caused by the photocationic polymerization initiator. Moreover, the photosensitizer is a compound that can further promote the action of the photosensitizer. Depending on the type of transparent resin film, it may be better to formulate photosensitizer and then further formulate photosensitizing additives.

The photosensitizer is preferably a compound that exhibits maximum absorption in light with a wavelength longer than 380 nm. Although the aforementioned photocationic polymerization initiators show maximum absorption at a wavelength near 300nm or shorter than 300nm, and generate cationic species or Lewis acids by sensing light of a wavelength near 300nm, the cations of the starting photocationic hardening component Aggregate, but just deploy The above-mentioned photosensitizers can more sensitive to light of longer wavelength than 300nm, especially more sensitive to light of longer wavelength than 380nm. The photosensitizer is beneficial to the use of anthracene compounds.

The anthracene compound is preferably a compound represented by the following formula (IVa).

(In the formula, R ⁴ and R ⁵ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbons or an alkoxyalkyl group having 2 to 12 carbons, and R ⁶ represents a hydrogen atom or a carbon number of 1 to 6的alkyl.)

Examples of the anthracene-based photosensitizer 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-9,10-dimethoxyanthracene or 2-ethyl-9,10-dimethoxyanthracene,

2-methyl-9,10-diethoxyanthracene or 2-ethyl-9,10-diethoxyanthracene,

2-methyl-9,10-dipropoxyanthracene or 2-ethyl-9,10-dipropoxyanthracene,

2-methyl-9,10-diisopropoxyanthracene or 2-ethyl-9,10-diisopropoxyanthracene,

2-methyl-9,10-dibutoxyanthracene or 2-ethyl-9,10-dibutoxyanthracene,

2-methyl-9,10-dipentyloxyanthracene or 2-ethyl-9,10-dipentyloxyanthracene,

2-methyl-9,10-dihexyloxyanthracene or 2-ethyl-9,10-dihexyloxyanthracene; etc.

By blending the above-mentioned photosensitizer in the photocurable adhesive, the curing property of the adhesive is improved. By blending 0.1 parts by mass or more of the photosensitizer to 100 parts by mass of the photocationic curable component, the curability of the photocurable adhesive is improved. On the other hand, when the blending amount of the photosensitizer is increased, problems such as precipitation during low-temperature storage may occur. Therefore, the blending amount of the photosensitizer is preferably 2 parts by mass or less relative to 100 parts by weight of the photocationic curable component. . From the viewpoint of maintaining the neutral gray of the polarizer, it is more advantageous to reduce the amount of the photosensitizer blended in a range where the adhesion between the polarizer and the transparent resin film is appropriately maintained, for example, compared to the photocationic curable component ( A) 100 parts by mass, the amount of the photosensitizer is preferably in the range of 0.1 to 0.5 parts by mass, and more preferably in the range of 0.1 to 0.3 parts by mass.

The photosensitizing assistant is preferably a naphthalene-based compound, and more preferably a naphthalene-based compound represented by formula (IVb).

(In the formula, R ⁷ and R ⁸ each independently represent an alkyl group having 1 to 6 carbon atoms.)

Naphthalene-based photosensitizers include: 4-methoxy-1-naphthol, 4-ethoxy-1-naphthol, 4-propoxy-1-naphthol, 4-butoxy-1-naphthalene Phenol, 4-hexoxy-1-naphthol, 1,4-dimethoxynaphthol, 1-ethoxy-4-methoxynaphthol, 1,4-diethoxynaphthol, 1 ,4-Dipropoxynaphthol, 1,4-dibutoxynaphthol, etc.

Compared with the case where the naphthalene-based photosensitizer is not blended in the photo-curable adhesive composition, the case of blending the naphthalene-based photosensitizer in the photo-curable adhesive composition is improved by blending the naphthalene-based photosensitizer. Adhesive curing properties. Such an effect can be exhibited by blending 0.1 parts by mass or more of a naphthalene-based photosensitizer with respect to 100 parts by mass of the photocationic curable component. On the other hand, when the blending amount of the naphthalene-based photosensitizer is increased, problems such as precipitation during low-temperature storage may occur. Therefore, the blending amount of the naphthalene-based photosensitizer is set based on 100 parts by mass of the photocationic curable component. It is preferably 5 parts by mass or less, and more preferably 3 parts by mass or less.

(5-5) Other ingredients

The photocurable adhesive composition may contain components other than the above. Other ingredients can include: thermal cationic polymerization initiators, polyols, ion trapping agents, antioxidants, light stabilizers, chain transfer agents, tackifiers, thermoplastic resins, fillers, flow regulators, plasticizers, waste Foaming agent, leveling agent, pigment, organic solvent, etc.

(Physical properties of light-curable adhesive composition)

The photocurable adhesive composition of the present invention can be used for bonding a polarizer and a transparent resin film. After coating the photocurable adhesive composition on the bonding surface of at least one of the polarizer and the transparent resin film, the polarizer and the transparent resin film are laminated via the adhesive layer, and then The agent will harden. Moreover, in order to improve the suitability of coating polarizers and/or transparent resin films Higher, the lower the viscosity of the photocurable adhesive composition, the better. Specifically, the photocurable adhesive is preferably set to have a viscosity at 25°C of 100 mPa·s or less.

In addition, before improving the adhesion between the polarizer and the protective film, the higher the storage elastic modulus of the adhesive layer obtained by curing the adhesive, the better. Specifically, the cured product of the photocurable adhesive should preferably have a storage elastic modulus of 1,000 MPa or more at 80°C.

[Polarizer]

In the present invention, a transparent resin film made of a transparent resin is bonded to at least one side of a polarizer through the photocurable adhesive composition of the present invention, and the photocurable adhesive composition is cured to produce a polarized light board.

(Polarizer)

The polarizer is composed of a polyvinyl alcohol-based resin film in which a dichroic dye is adsorbed and oriented. The polyvinyl alcohol-based resin film constituting the polarizer is obtained by saponifying a polyvinyl acetate-based resin. In addition to polyvinyl acetate which is a homopolymer of vinyl acetate, the polyvinyl acetate resin can also be a copolymer of vinyl acetate and other monomers that can be copolymerized with vinyl acetate. Examples of other monomers that can be 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 in the range of 85 to 100 mol%, preferably 98 to 100 mol%. The polyvinyl alcohol resin can be further modified. For example, polyvinyl formal or polyvinyl acetal modified with aldehydes can also be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually 1,000 to 10,000, preferably in the range of 1,500 to 5,000.

The polarizer can be manufactured through the following steps: a step of uniaxially stretching such a polyvinyl alcohol-based resin film; dyeing the polyvinyl alcohol-based resin film with a dichroic dye and adsorbing The step of the dichroic dye; the step of treating the polyvinyl alcohol resin film on which the dichroic dye has been adsorbed with a boric acid aqueous solution.

Uniaxial stretching may be performed before dyeing with a dichroic dye, or simultaneously with dyeing with a dichroic dye, or after dyeing with a dichroic dye. When uniaxial stretching is performed after dyeing with a dichroic dye, this uniaxial stretching may be performed before or during the boric acid treatment. In addition, of course, it is also possible to perform uniaxial stretching in a plurality of stages of these stages. As far as uniaxial extension is concerned, it may be uniaxial extension between rollers of different rotation speeds, or it may be uniaxial extension using a heated roller. In addition, it may be dry stretching in which it is stretched in the atmosphere, or wet stretching in which it is stretched while being swollen by a solvent. The stretching ratio is usually about 4 to 8 times.

To dye the polyvinyl alcohol-based resin film with a dichroic dye, for example, the polyvinyl alcohol-based resin film may be immersed in an aqueous solution containing the dichroic dye. Specifically, iodine or a dichroic organic dye can be used for the dichroic dye system.

When iodine is used as a dichroic dye, a method of dyeing a polyvinyl alcohol resin film by soaking it in an aqueous solution containing iodine and potassium iodide is usually adopted. 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. The temperature of the aqueous solution is usually about 20 to 40°C, and the immersion time (dyeing time) in the 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 a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic organic dye to dye is generally adopted. The content of the dichroic organic dye in the aqueous solution is usually about 1×10 ^-3 to 1×10 ^-2 parts by mass per 100 parts by mass of water. This aqueous solution may contain inorganic salts such as sodium sulfate. The temperature of the aqueous solution is usually about 20 to 80°C, and the immersion time (dyeing time) in the aqueous solution is usually about 30 to 300 seconds.

The boric acid treatment after dyeing with a dichroic dye is performed by immersing the dyed polyvinyl alcohol-based resin film in a boric acid aqueous solution. The content of boric acid in the boric acid aqueous solution is usually about 2 to 15 parts by mass per 100 parts by mass of water, preferably about 5 to 12 parts by mass. When iodine is used as a 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 mass per 100 parts by mass of water, preferably about 5 to 15 parts by mass. The immersion time in the boric acid aqueous solution is usually about 100 to 1,200 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 above 50°C, preferably 50 to 85°C.

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

The thickness of the polarizer can be about 3 to 30 μm.

(Transparent resin film)

If the transparent resin film has been used as a protective film for a polarizing plate in the past, there is no particular limitation. For example, it may be composed of an acetyl cellulose resin film including triacetyl cellulose, or a resin film having a lower moisture permeability than triacetyl cellulose. The moisture permeability of triacetyl cellulose is approximately 400 g/m ² /24 hours.

In a preferred embodiment, the transparent resin film attached to at least one side of the polarizer can be made of acetyl cellulose resin. In particular, the transparent resin film attached to one side of the polarizer may be composed of an acetyl cellulose resin prepared with an ultraviolet absorber. In another preferred form, the transparent resin film attached to at least one side of the polarizer may be composed of a resin film with a lower moisture permeability than triacetate cellulose, for example, a moisture permeability of 300 g/m ² / Resin film construction for 24 hours or less. Examples of resins constituting such a resin film with low moisture permeability include amorphous polyolefin resins, polyester resins, acrylic resins, polycarbonate resins, and chain polyolefin resins. Among these, it is particularly preferable to use amorphous polyolefin resin, polyester resin, and chain polyolefin resin. Furthermore, in another preferred form, a protective film made of acetyl cellulose resin can be attached to one side of the polarizer via the aforementioned adhesive layer, and then attached to the other side of the polarizer. A protective film made of a transparent resin with a low moisture permeability as described above is bonded through the aforementioned adhesive layer.

Acetyl cellulose resin is a resin in which at least a part of hydroxyl groups in cellulose is esterified with acetic acid, and may be a mixed ester in which at least part of the hydroxyl groups is esterified with acetic acid and partially with other esterification. Specific examples of the acetyl cellulose resin include triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, and cellulose acetate butyrate.

Polymerization of amorphous polyolefin resins such as norbornene, tetracyclododecene (alias "dimethyl octahydronaphthalene"), or compounds having substituents bonded thereto The polymer of the unit may be a copolymer obtained by copolymerizing a cyclic olefin, a chain olefin and/or an aromatic vinyl compound. When it is a homopolymer of cyclic olefin or one of two or more cyclic olefins In the case of a copolymer, a double bond remains due to ring-opening polymerization, so the hydrogenated product can usually be used as an amorphous polyolefin resin. Among them, thermoplastic norbornene-based resins are particularly representative.

The polyester resin is a polymer obtained by the condensation polymerization of a dibasic acid and a diol, and a representative one is polyethylene terephthalate. Acrylic resin is a polymer with methyl methacrylate as the main monomer. In addition to the homopolymer of methyl methacrylate, it can also be methyl methacrylate and acrylate such as methyl acrylate or aromatic Copolymers of vinyl compounds. 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 resin is a polymer whose main monomer is a chain olefin such as ethylene or propylene, and may be a homopolymer or a copolymer. Among them, the homopolymer of propylene and the copolymer of propylene and a small amount of ethylene are particularly representative.

Such a transparent resin film may have various surface treatment layers such as a hard coat layer, an anti-reflection layer, an anti-glare layer, or an anti-static layer on the surface opposite to the surface bonded to the polarizer. When the protective film includes the formation of such a surface treatment layer, the thickness of the protective film can be about 5 to 150 μm. The thickness is preferably 10 μm or more, more preferably 120 μm or less, and more preferably 100 μm or less.

(Method of manufacturing polarizing plate)

For the manufacture of a polarizer, a coating layer of a photocurable adhesive composition is formed on one or both of the bonding surfaces of the polarizer and the transparent resin film, and the polarizer and the transparent resin film are passed through the coating layer. The coating layer is bonded together, and the coating layer of the uncured photocurable adhesive formed in this way is cured by irradiation of active energy rays, so that the transparent resin film is fixedly attached to the polarizer. The coating layer of the photocurable adhesive can be formed on the bonding surface of the polarizer or on the The bonding surface of the transparent resin film. For the formation of the coating layer, various coating methods such as doctor blade, wire rod, die coater, comma coater, gravure coater, etc. can be used to form the coating. Floor. In addition, it is also possible to adopt a method in which the polarizer and the transparent resin film are continuously supplied so that the bonding surfaces of the polarizer and the transparent resin film are inside, while the adhesive is cast between the polarizer and the transparent resin film. Because each coating method has the most suitable viscosity range, the use of solvents to adjust the viscosity is also a useful technique. Regarding the solvent used for this, although it is possible to use a solvent that does not degrade the optical performance of the polarizer and dissolves the photocurable adhesive composition well, the kind is not particularly limited. For example, organic solvents such as hydrocarbons typified by toluene and esters typified by ethyl acetate can be used. The thickness of the adhesive layer is usually 20 μm or less, preferably 10 μm or less, and more preferably 5 μm or less. If the adhesive layer becomes thicker, the reaction rate of the adhesive decreases and the heat and humidity resistance of the polarizing plate tends to deteriorate.

When bonding the polarizer and the transparent resin film, it can also be applied on one or both of the bonding surfaces of the polarizer and the transparent resin film before forming the coating layer of the photocurable adhesive composition Such as corona discharge treatment, plasma treatment, flame treatment, primer treatment or anchor coating treatment for easy bonding.

The light source used to irradiate the coating layer of the photocurable adhesive composition with active energy rays may be one that generates ultraviolet rays, electron rays, X-rays, etc. In particular, it can be suitably used for those with a luminous distribution with a wavelength below 400nm, such as low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, metal halide lamps, etc. The active energy ray irradiation intensity to the photocurable adhesive depends on the composition of the purpose. Although there is no particular limitation, the irradiation intensity is set to the wavelength region where the activation of the photocationic polymerization initiator is effective It is preferably from 5 to 3,000 mW/cm ² . If the light irradiation intensity of the photocurable adhesive is too small, the reaction time will become too long; on the other hand, when the light irradiation intensity is too large, it may be caused by the radiant heat from the lamp and the photocurable adhesive Heat generation during polymerization causes yellowing of the photocurable adhesive and deterioration of the polarizer. The light irradiation time of the photocurable adhesive is limited by the hardened composition. Although there is no particular limitation, the cumulative light amount expressed by the product of the irradiation intensity and the irradiation time is set to 10 to 5,000 mJ/cm ^{2 is} better. If the cumulative amount of light for the photocurable adhesive is too small, the production of active species derived from the photocationic polymerization initiator may be insufficient, and the resulting adhesive layer may not be cured sufficiently; on the other hand, If the accumulated light amount is to be made larger, the irradiation time will become very long, which is disadvantageous for improving the yield.

In the case of laminating transparent resin films on both sides of the polarizer, the active energy rays can be irradiated from either side of the transparent resin film, but for example, one transparent resin film contains an ultraviolet absorber and the other transparent resin film does not. When the ultraviolet absorber is contained, it is preferable to irradiate the active energy ray from the side of the transparent resin film that does not contain the ultraviolet absorber in terms of effectively using the irradiated active energy rays and increasing the curing speed.

[Layered Optical Components]

The polarizing plate of the present invention can be laminated with optical layers having optical functions other than the polarizing plate to form a laminated optical member. Typically, although the optical layer can be laminated on the transparent resin film of the polarizing plate via an adhesive or adhesive to form a laminated optical member, it is also possible, for example, to pass on one side of the polarizer according to the present invention. The light-curable adhesive is bonded to the transparent resin film, and the optical layer is laminated on the other side of the polarizer via the adhesive and adhesive. If the latter In the case, if the photocurable adhesive specified in the present invention is used as the adhesive for attaching the polarizer and the optical layer, the optical layer may also be the transparent resin film specified in the present invention.

When enumerating the optical layer that can be laminated on the polarizing plate, for the polarizing plate arranged on the back side of the liquid crystal cell, there are reflective layers and semi-transmissive reflective layers laminated on the side opposite to the side of the polarizing plate facing the liquid crystal cell , Light diffusion layer, light concentrator, brightness enhancement film, etc. In addition, for either the polarizing plate arranged on the front side of the liquid crystal cell and the polarizing plate arranged on the back side of the liquid crystal cell, there is a retardation film laminated on the side of the polarizing plate facing the liquid crystal cell. .

The reflective layer, the semi-transmissive reflective layer, or the light diffusion layer is provided as a reflective polarizer (optical member), a semi-transmissive reflective polarizer (optical member), or a diffused polarizer (optical member), respectively. The reflective polarizer is a type of liquid crystal display that can be used to reflect incident light from the visible side to display. Since light sources such as a backlight can be omitted, it is easy to make the liquid crystal display thinner. In addition, semi-transmissive polarizers can be used in liquid crystal displays, which are reflective in bright places and display light from the backlight in dark places. As an optical member of a reflective polarizer, for example, a foil made of metal such as aluminum or a vapor-deposited film can be attached to a transparent resin film on a polarizer to form a reflective layer. The optical member as a semi-transmissive polarizing plate can be formed by forming the aforementioned reflective layer as a half mirror, or attaching a reflective plate containing pearl pigments and the like and exhibiting light transmittance to the polarizing plate. On the other hand, as an optical member of a diffusion-type polarizing plate, for example, the following various methods are used to form a fine uneven structure on the surface: a method of applying a matting treatment to a transparent resin film on a polarizing plate, and a method of coating a resin containing particles , Follow the method of film containing particles, etc.

In addition, it is also possible to form an optical member that functions as a polarizing plate for both reflection and diffusion. In this case, for example, a fine concavo-convex structure in a diffused polarizer can be used. The surface is equipped with a reflective layer reflecting its uneven structure. The reflective layer of the fine concavo-convex structure has advantages such as diffused reflection of incident light, prevention of directivity and glare, and suppression of uneven brightness. In addition, the particle-containing resin layer and film also have the following advantages: the incident light and its reflected light are diffused when penetrating the particle-containing layer, and the unevenness of brightness can be suppressed. The reflective layer reflecting the fine uneven structure on the surface can be formed by directly attaching metal to the surface of the fine uneven structure by methods such as vacuum evaporation, ion plating, or sputtering. The fine particles formulated to form the surface fine uneven structure include, for example, inorganic fine particles such as silicon dioxide, aluminum oxide, titanium oxide, zirconium oxide, tin oxide, indium oxide, cadmium oxide, and antimony oxide with an average particle size of 0.1 to 30 μm. ; Such as cross-linked or uncross-linked polymer organic particles.

The condensing plate is used for the purpose of controlling the optical path, so it can be formed as a prismaticprism array sheet, a lens array sheet, or a dot attached sheet.

Brightness enhancement films are used for the purpose of improving the brightness of liquid crystal displays. Examples of these include: reflective polarizing separators, which are layers of films with different refractive index anisotropy, and are designed to have reflectivity. Those that produce anisotropy; circularly polarized separators are those that support an oriented film of cholesteric liquid crystal polymer or an oriented liquid crystal layer of the oriented film of cholesteric liquid crystal polymer on a film substrate; etc.

On the other hand, the purpose of use of the above-mentioned retardation film that functions as an optical layer is to compensate for the retardation caused by the liquid crystal cell. Examples thereof include birefringent films formed from stretched films of various plastics, films in which discotic liquid crystals and nematic liquid crystals are oriented and fixed, and those having the above-mentioned liquid crystal layer formed on a film substrate. When a liquid crystal layer is formed on a film substrate, it is preferable to use a cellulose resin film such as triacetyl cellulose as the film substrate.

Examples of the plastic forming the birefringent film include amorphous polyolefin resins, polycarbonate resins, acrylic resins, chain polyolefin resins such as polypropylene, polyvinyl alcohol, polystyrene, and Esters, polyamides, etc. The stretched film can be processed in a suitable manner such as uniaxial or biaxial. In addition, the retardation film can also be used in combination of two or more sheets for the purpose of controlling optical properties such as widening.

Those that include a retardation film as an optical layer other than the polarizing plate in the laminated optical member can effectively perform optical compensation when applied to a liquid crystal display device, and therefore can be suitably used. Regarding the retardation value (in-plane and thickness direction) of the retardation film, it is only necessary to select the most suitable one according to the applied liquid crystal cell.

The laminated optical member system can combine a polarizing plate and one layer or two or more layers selected from the above-mentioned various optical layers according to the purpose of use to form a two-layer or three-layer or more laminated body. In this case, the various optical layers forming the laminated optical member can be integrated with the polarizing plate using adhesives and adhesives, but the adhesives and adhesives used for this purpose can form an adhesive layer or an adhesive layer well. , There is no special restriction. From the viewpoints of ease of work and prevention of light strain, it is better to use an adhesive (also known as a pressure-sensitive adhesive). As for the adhesive, acrylic polymers, polysiloxane polymers, polyesters, polyurethanes, polyethers, etc. can be used as base polymers. Among them, the use of acrylic adhesives has excellent optical transparency, maintains moderate wettability and cohesion, excellent adhesion to the substrate, and more weather resistance and heat resistance, etc., when heated or added It is better to have no peeling problems such as floating and peeling under wet conditions. In the acrylic adhesive, the alkyl ester of (meth)acrylic acid with a carbon number of 20 or less, such as methyl, ethyl, or butyl, and (meth)acrylic acid or hydroxyethyl (meth)acrylate, etc. Acrylic monomers containing functional groups are formed, and the glass transition temperature is preferably below 25°C Below, it is more preferable to formulate an acrylic copolymer with a weight average molecular weight of 100,000 or more under 0°C, which is useful as a base polymer.

The formation of the adhesive layer on the polarizing plate can be carried out, for example, by dissolving or dispersing the adhesive composition in an organic solvent such as toluene and ethyl acetate to prepare a 10 to 40% by mass solution, and The prepared solution is directly coated on the polarizing plate; the adhesive layer is formed on the protective film in advance, and then the adhesive layer is transferred to the polarizing plate. Although the thickness of the adhesive layer can be determined in accordance with its adhesive strength, etc., it is suitable to be in the range of about 1 to 50 μm.

In addition, the adhesive layer can be prepared as needed: fillers made of glass fibers and glass particles, resin particles, metal powders and other inorganic powders; pigments and colorants, antioxidants, ultraviolet absorbers, etc. As for ultraviolet absorbers, there are salicylate-based compounds, benzophenone-based compounds, benzotriazole-based compounds, cyanoacrylate-based compounds, nickel complex salt-based compounds, and the like.

The laminated optical member can be arranged on one side or both sides of the liquid crystal cell. Any liquid crystal cell can be used, for example, active matrix driven type represented by thin film transistor type, simple matrix driven type represented by super twisted nematic type, etc. can be used. The liquid crystal cell forms a liquid crystal display. For the adhesion of the laminated optical member and the liquid crystal cell, usually the same adhesive as the above-mentioned adhesive can be used.

[Example]

The following examples are presented to more specifically illustrate the present invention, but the present invention is not limited to these examples. If there is no special instructions, the content and usage amount in the example are expressed in% and parts. Quality benchmark. In addition, the photocationic curable component and photocationic polymerization initiator used in the following examples are described later, and are represented by the following symbols.

(Synthesis example 1)

Synthesis of compound represented by formula (a1-3)

According to the method described in WO2014/157498, the compound represented by the following formula (a1-3) was synthesized, and separated and purified by liquid chromatography.

In addition, the conditions of liquid chromatography are as follows.

The separation of the epoxide (a1) was carried out by liquid chromatography.

(Analysis conditions)

Measuring device: LC-20+FRC-10A [manufactured by Shimadzu Corporation]

Column: ZORBAX SB-C18 (5μm, 9.4×150mm)

Column temperature: 40℃

Mobile phase: A is water, B is acetonitrile

Gradient: 0 minutes A=90%, B=10%

30 minutes A=0%, B=100%

35 minutes A=0%, B=100%

35.1 minutes A=90%, B=10%

50 minutes stop (total analysis time 50 minutes)

Flow rate: 5.0mL/min

Detection: UV absorption detector (wavelength: 254nm)

(A) Photocationic curable ingredients

(a1-1) 7-oxabicyclo[4.1.0]heptane-3-methanol manufactured by Synnovator Product List [In the above formula (I), R ¹ =CH ₂ OH compound]

(a1-2) Syna-Epoxy30 manufactured by Synasia [In the above formula (I), R ¹ =CH ₂ OCOC ₂ H ₅ compound]

(a1-3) The compound represented by formula (a1-3) synthesized in the above synthesis example

(a2) 3,4-Epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate [In the aforementioned formula (II), R ² =R ³ =H, Z ¹ =-COOCH _2- compound of〕,

(a3) Neopentyl glycol diglycidyl ether [in the aforementioned formula (III), Z ² = -CH ₂ C(CH ₃ ) ₂ CH ₂ -compound],

(a4) 2-Ethylhexyl glycidyl ether (EX121 manufactured by Nagase Chemtex)

(B) Photocationic polymerization initiator (referred to as "initiator" in the table)

(b1) Propylene carbonate 50% solution of a mixture of the compound represented by the formula (B1) and the compound represented by the formula (B2)

[Example 1 to Example 3 and Comparative Example 1]

(1) Preparation of photocurable adhesive composition

The above-mentioned photocationic curable component and photocationic polymerization initiator were mixed in the blending ratio (unit: part) shown in Table 1, and then defoamed to prepare a photocurable adhesive liquid. In addition, the photocationic polymerization initiator is the value of the solid content.

[Table 1]

(2) Measurement of the viscosity of the photocurable adhesive composition at 25°C

Using the Toki Sangyo Co., Ltd. E-type viscometer "TVE-25L", the viscosity (mPa‧s) of each photocurable adhesive composition (adhesive liquid) prepared in (1) above was measured at a temperature of 25°C. . The results are shown in Table 2.

(3-1) Manufacturing of polarizer

A long strip of polyvinyl alcohol (PVA) raw film with a thickness of 60μm [Kuraray Vinylon VF-PE #6000, manufactured by Kuraray Co., Ltd., with an average degree of polymerization of 2400, and a degree of saponification of more than 99.9 mol%] from the roll. At the same time, it was continuously transported and immersed in an expansion bath formed of pure water at 30°C for a residence time of 79 seconds (expansion step). Then, the film removed from the expansion bath is retained Immerse in a 30°C dyeing bath containing iodine with a potassium iodide/boric acid/water ratio of 1/0.3/100 (weight ratio) for 123 seconds (dyeing step). Next, the film taken out of the dyeing bath was immersed in the first crosslinking bath at 53°C at a residence time of 44 seconds at a potassium iodide/boric acid/water ratio of 11/3.8/100 (weight ratio), and then allowed to stay for a residence time of 6 Soak in the second cross-linking bath at 40°C with a potassium iodide/boric acid/water ratio of 11/3.8/100 (weight ratio) (cross-linking step). In the dyeing step and the cross-linking step, longitudinal uniaxial stretching is performed by stretching between rolls in the bath. The total stretching ratio based on the raw film is 5.65 times.

(3-2) Production of polarizing plate

Prepare a retardation film with a thickness of 50 μm formed by a 60 μm-thick triacetyl cellulose resin (TAC) film containing ultraviolet absorbers and a norbornene-based resin (COP: cycloolefin polymer) [trade name "ZEONOR", Japan ZEON joint stock company system]. The surface of the triacetyl cellulose resin film with a thickness of 60μm and the retardation film with a thickness of 50μm is protected by corona discharge treatment. On the surface of the corona discharge treatment, the adhesive coating device is used to prepare (1) Each adhesive liquid is coated on one side of each film. The coating surface of each film was attached to the polarizer manufactured in (3-1) above, and the total cumulative light intensity was about 350mJ/cm ² (measurement device: measured value obtained by UV Power Puck II manufactured by Fusion UV) Ultraviolet rays (UVA).

(4) Adhesion

The polarizing plate produced in (3) above was cut into a size of 200 mm in length×25 mm in width. Then, an acrylic adhesive layer was provided on the side of the triacetyl cellulose film with a thickness of 60 μm, and a test piece for measuring the peel strength between the triacetyl cellulose film with a thickness of 60 μm and the polarizer was prepared. Attach the adhesive layer of the test piece to the glass plate, insert the blade of the cutter between the polarizer and the protective film on the adhesive side (triacetyl cellulose film with a thickness of 60 μm), and peel off from the end in the length direction Lift 30mm, and grasp the peeled part with the grip part of the testing machine. The test piece in this state was held in a gas environment with a temperature of 23°C and a relative humidity of 55% in accordance with JIS K 6854-2: 1999 "Adhesives-Peeling Adhesion Strength Test Method-Part 2: 180° Peeling" A 180-degree peel test was performed at a moving speed of 300 mm/min, and an average peel force of 170 mm in length excluding 30 mm of the gripping part was obtained. The results are shown in Table 2.

[Table 2]

As shown in Table 2, the polarizing plate using the photocurable adhesive composition of the present invention has good adhesion.

Claims (8)

A light-curing adhesive composition containing the following (A) and (B); (A) A photocationic curable component containing an epoxy compound represented by the following formula (I) (B) Photocationic polymerization initiator

In the formula (I), R ¹ represents an alkyl group with carbon numbers of 1 to 8 which may have at least one hydroxyl group, and the -CH ₂ -contained in the alkyl group can be replaced by an ester bond and can be interrupted by at least one ester bond Alkyl ester with a total carbon number of 2 to 8, a hydroxyl group, a carboxyl group, a group represented by the following formula (Ia) or a group represented by the following formula (Ib);

X ¹ , X ² , X ¹¹ and X ¹² each independently represent a single bond or an alkanediyl group having 1 to 3 carbon atoms; Y ¹ and Y ¹¹ each independently represent a cyclopentanyl group or a cyclic saturated hydrocarbon group having 3 to 8 carbons. The cyclopentyl group or a cyclic saturated hydrocarbon group having 3 to 8 carbons may have a hydroxyl group and a carbon number of 2 to The alkylcarbonyloxy group of 8, the alkyl group having 1 to 6 carbons, and -CH ₂ -contained in the alkyl group may be replaced by -CO-. The photocurable adhesive composition as described in item 1 of the scope of patent application, wherein: The photocurable adhesive composition system contains 1 to 10 parts by mass of (B) photocationic polymerization initiator relative to 100 parts by mass of (A) photocationic curable component; The aforementioned photocationic curable components are based on their total amount and contain: (A1) Epoxy compound represented by formula (I) 0.1 to 20% by mass (A2) 50 to 90% by mass of the alicyclic diepoxy compound represented by the following formula (II),

In the formula, R ² and R ³ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, but the alkyl group may have an alicyclic structure when the alkyl group has 3 or more carbon atoms; Z ¹ represents an oxygen atom, an alkanediyl group having 1 to 6 carbon atoms, or a divalent group represented by any of the following formulas (Ia) to (Id);

Among them, Y ² to Y ⁵ respectively represent alkanediyl groups having 1 to 20 carbon atoms, but may have an alicyclic structure when the carbon number is 3 or more; a and b represent an integer from 0 to 20, respectively. The photocurable adhesive composition described in item 1 or 2 of the scope of patent application further contains (A3) 1 to 70% by mass of the aliphatic diglycidyl compound represented by the following formula (III);

In the formula, Z ² represents a branched alkylene group having 3 to 8 carbon atoms or a divalent group represented by the formula -C _m H _2m -Z ³ -C _n H _2n -, where -Z ³ -represents -O -, -CO-O- or -O-CO-, one of m and n represents an integer of 1 or more, the other represents an integer of 2 or more, but the sum of the two is 8 or less, and C _m H _{One of 2m} and C _n H _2n represents a branched divalent saturated hydrocarbon group. The photocurable adhesive composition described in any one of items 1 to 3 in the scope of the patent application further contains 0.1 to 5 parts by mass of an anthracene compound represented by the following formula (IVa) or formula (IVb) One or more of the naphthalene compounds represented by );

In the formula, R ⁴ and R ⁵ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbons or an alkoxyalkyl group having 2 to 12 carbons, and R ⁶ represents a hydrogen atom or a carbon number of 1 to 6 alkyl;

In the formula, R ⁷ and R ⁸ each independently represent an alkyl group having 1 to 6 carbon atoms. A light-curing adhesive layer is formed of the light-curing adhesive composition described in any one of items 1 to 4 in the scope of patent application. A laminated body is a laminated body formed by laminating a polarizer, an adhesive layer, and a transparent resin film in the order, in which, The aforementioned adhesive layer is the light-curing adhesive layer described in item 5 of the scope of the patent application. A laminated optical component is formed of a laminated body described in item 6 of the scope of patent application and a laminated body of other optical layers. The laminated optical member described in claim 7, wherein the other optical layer includes a retardation film.