JP7406594B2 - Polarizing plate and its manufacturing method - Google Patents

Description

The present invention relates to a polarizing plate used in liquid crystal display devices and a method for manufacturing the same.

BACKGROUND ART Adhesives containing a cationic polymerizable resin, a photopolymerization initiator, and a thermal polymerization initiator are known as adhesives used when assembling optical components and the like (Patent Documents 1 and 2). This kind of adhesive has a curing effect not only by light irradiation but also by heating, so it can bond areas that will be in the shadow when assembling optical parts, etc., so it can be used, for example, for assembling optical materials such as semiconductor laser modules. Available for

JP2013-95881A Japanese Patent Application Publication No. 2003-96425

On the other hand, adhesives are also used in polarizing plates widely used in liquid crystal display devices and the like, and a polarizing plate usually has a structure in which a protective film is laminated on one or both sides of a polarizer via an adhesive. In recent years, polarizing plates have been used for various purposes, such as mobile devices such as smartphones and tablet terminals, and are sometimes placed in high temperature or high temperature and high humidity environments.
Therefore, even under such an environment, it is required that lifting, peeling, etc. at the interface between the adhesive and the polarizer or protective film can be suppressed, and that the optical properties do not deteriorate. In particular, polarizing plates have strong shrinkage stress in high-temperature environments, so the adhesive used for polarizing plates requires higher durability than adhesives used to assemble general optical components. be done.

Therefore, an object of the present invention is to provide a polarizing plate that exhibits excellent durability even under high temperature and high humidity environments, and a method for manufacturing the same.

The present inventor has completed the present invention as a result of intensive studies to solve the above problems. That is, the present invention includes the following.

［式中、Ｒ^１は置換基を有してもよいＣ_６－１４アリール基又は置換基を有していてもよいＣ_３－１４芳香族複素環基であり、Ｒ^２～Ｒ^４は、互いに独立して、Ｃ_１－１８アルキル基、置換基を有してもよいＣ_６－１４アリール基又は置換基を有していてもよいＣ_３－１４芳香族複素環基であり、前記置換基はＣ_１－１８アルキル基、ハロゲン化Ｃ_１－８アルキル基、Ｃ_２－１８アルケニル基、Ｃ_２－１８アルキニル基、Ｃ_６－１４アリール基、Ｃ_３－１４芳香族複素環基、ニトロ基、水酸基、シアノ基、－ＯＲ^５で表されるアルコキシ基若しくはアリールオキシ基、Ｒ^６ＣＯ－で表されるアシル基、Ｒ^７ＣＯＯ－で表されるアシロキシ基、－ＳＲ^８で表されるアルキルチオ基若しくはアリールチオ基、－ＮＲ^９Ｒ^１０で表されるアミノ基、又はハロゲン原子であり、前記Ｒ^５～Ｒ^８はＣ_１－８アルキル基、Ｃ_６－１４アリール基又はＣ_３－１４芳香族複素環基であり、前記Ｒ^９及びＲ^１０は水素原子、Ｃ_１－８アルキル基、Ｃ_６－１４アリール基又はＣ_３－１４芳香族複素環基である］
で表されるアニオン又は下記式（２）

［式中、Ｒｆは水素の８０％以上がフッ素原子で置換された、同一又は異なるアルキル基を示し、aは１～５の整数である］
で表されるアニオンであるイオン性化合物であり、
前記第２の酸発生剤は、硬化温度が１２０℃以上、かつ活性エネルギー線により酸を発生するイオン性化合物である、偏光板。
［２］前記接着剤層は、活性エネルギー線を前記接着剤に照射した後、加熱することにより硬化されたものである、［１］に記載の偏光板。
［３］第１の酸発生剤は下記式（３）

［式中、Ｒ^１１及びＲ^１２は互いに独立して、アルキル基、アラルキル基、アリール基又は芳香族複素環基を示し、Ｒ^１３は置換基を有してもよいフェニル基を示し、Ｘ^－は、前記式（１）又は式（２）で表されるアニオンである］
で表されるイオン性化合物である［１］又は［２］に記載の偏光板。
［４］第２の酸発生剤のカウンターアニオンは、前記式（１）若しくは前記式（２）で表されるアニオン、又はＰＦ_６ ^－である［１］～［３］のいずれかに記載の偏光板。
［５］第２の酸発生剤のカウンターカチオンは、スルホニウム系カチオンである、［１］～［４］のいずれかに記載の偏光板。
［６］カチオン重合性化合物は、エポキシ化合物、オキセタン化合物及びビニル化合物からなる群から選択される少なくとも１種の化合物を含む、［１］～［５］のいずれかに記載の偏光板。
［７］保護フィルムは、セルロース系樹脂、（メタ）アクリル系樹脂、ポリオレフィン系樹脂、ポリエステル系樹脂及びポリカーボネート系樹脂からなる群から選択される少なくとも１種の樹脂を含む、［１］～［６］のいずれかに記載の偏光板。
［８］［１］～［７］のいずれかに記載の偏光板の製造方法であって、
（ａ）偏光子及び／又は保護フィルムに接着剤を塗布する工程
（ｂ）偏光子と保護フィルムを積層する工程
（ｃ）工程（ｂ）で得た積層体に活性エネルギー線を照射する工程、及び
（ｄ）次いで積層体を加熱する工程
を含む、方法。 [1] A polarizing plate comprising a polarizer and a protective film laminated on at least one surface of the polarizer via an adhesive layer, the adhesive layer comprising a cationically polymerizable compound, a first A cured adhesive containing an acid generator and a second acid generator,
The first acid generator is an ionic compound having a curing temperature of less than 120°C, and the counter anion constituting the ionic compound is represented by the following formula (1).

[Wherein, R ¹ is a C _6-14 aryl group which may have a substituent or a C _3-14 aromatic heterocyclic group which may have a substituent, and R ² to R ⁴ are independently of each other, they are a C _1-18 alkyl group, a C _6-14 aryl group which may have a substituent, or a C _3-14 aromatic heterocyclic group which may have a substituent; The groups include C _1-18 alkyl group, halogenated C _1-8 alkyl group, C _2-18 alkenyl group, C _2-18 alkynyl group, C _6-14 aryl group, C _3-14 aromatic heterocyclic group, nitro group, hydroxyl group, cyano group, alkoxy group or aryloxy group represented by -OR ⁵ , acyl group represented by R ⁶ CO-, acyloxy group represented by R ⁷ COO-, represented by -SR ⁸ An alkylthio group or an arylthio group, an amino group represented by -NR ⁹ R ¹⁰ , or a halogen atom, and R ⁵ to R ⁸ are a C _1-8 alkyl group, a C _6-14 aryl group, or a C _3-14 aromatic group. and R ⁹ and R ¹⁰ are a hydrogen atom, a C _1-8 alkyl group, a C _6-14 aryl group, or a C _3-14 aromatic heterocyclic group]
Anion represented by or the following formula (2)

[In the formula, Rf represents the same or different alkyl group in which 80% or more of hydrogen atoms are substituted with fluorine atoms, and a is an integer from 1 to 5]
It is an ionic compound that is an anion represented by
In the polarizing plate, the second acid generator is an ionic compound having a curing temperature of 120° C. or higher and generating acid in response to active energy rays.
[2] The polarizing plate according to [1], wherein the adhesive layer is cured by heating after irradiating the adhesive with active energy rays.
[3] The first acid generator has the following formula (3)

[In the formula, R ¹¹ and R ¹² independently represent an alkyl group, an aralkyl group, an aryl group, or an aromatic heterocyclic group, R ¹³ represents a phenyl group which may have a substituent, and X ^- is an anion represented by the above formula (1) or formula (2)]
The polarizing plate according to [1] or [2], which is an ionic compound represented by:
[4] The counter anion of the second acid generator is an anion represented by the above formula (1) or the above formula (2), or PF ₆ ^- according to any one of [1] to [3]. Polarizer.
[5] The polarizing plate according to any one of [1] to [4], wherein the counter cation of the second acid generator is a sulfonium cation.
[6] The polarizing plate according to any one of [1] to [5], wherein the cationically polymerizable compound contains at least one compound selected from the group consisting of an epoxy compound, an oxetane compound, and a vinyl compound.
[7] The protective film contains at least one resin selected from the group consisting of cellulose resin, (meth)acrylic resin, polyolefin resin, polyester resin, and polycarbonate resin, [1] to [6] ] The polarizing plate according to any one of.
[8] A method for manufacturing a polarizing plate according to any one of [1] to [7], comprising:
(a) a step of applying an adhesive to a polarizer and/or a protective film; (b) a step of laminating a polarizer and a protective film; (c) a step of irradiating the laminate obtained in step (b) with active energy rays; and (d) then heating the laminate.

According to the present invention, it is possible to provide a polarizing plate that has excellent durability even under environments such as high temperature and high humidity.

FIG. 1 is a schematic cross-sectional view showing an example of the layer structure of a polarizing plate according to the present invention.

<Polarizing plate>
The polarizing plate of the present invention includes a polarizer and a protective film laminated on at least one surface of the polarizer via an adhesive layer.
FIG. 1 is a schematic cross-sectional view showing an example of the layer structure of a polarizing plate according to the present invention. The polarizing plate shown in FIG. 1 includes a first protective film 10, a first adhesive layer 15, a polarizer 30, a second adhesive layer 25, and a second protective film 20 in this order. That is, the first protective film 10 is laminated on one side of the polarizer 30 via the first adhesive layer 15, and the second protective film 20 is laminated on the other side of the polarizer 30 via the second adhesive layer 25. Laminated on.

The polarizing plate according to the present invention is not limited to the example shown in FIG. 1, and may include layers other than those described above. Specific examples of other layers include, for example, an adhesive layer laminated on the outer surface of the first protective film 10 and/or the second protective film 20; a separate film ("peelable") laminated on the outer surface of the adhesive layer; A protective film laminated on the outer surface of the first protective film 10 and/or the second protective film 20 (also referred to as a "surface protective film"); 2. It is an optically functional film or the like that is laminated on the outer surface of the protective film 20 via an adhesive layer or a pressure-sensitive adhesive layer.

The polarizing plate according to the present invention includes an elongated polarizing plate having the above-mentioned layer structure, a wound roll thereof, a polarizing plate sheet cut from the elongated object and the wound roll, or a polarizing plate sheet cut out from the elongated object and the wound roll, or further It may also be a sheet body cut into small pieces.
In this specification, durability refers to the durability of the adhesive layer and the adjacent polarizer or protective film in, for example, high-temperature environments, high-temperature, high-humidity environments, environments with repeated high and low temperatures, etc. Characteristics that can suppress lifting and peeling at the interface (sometimes called peeling resistance), characteristics that can suppress deterioration of optical properties (sometimes called deterioration resistance), and suppressing warping (or curling) of polarizing plates. characteristics such as curl resistance (sometimes referred to as curl resistance).

[1] Adhesive layer The adhesive layer constituting the polarizing plate of the present invention is a cured adhesive containing a predetermined cationic polymerizable compound, a first acid generator, and a second acid generator described below. It is preferably composed of a cured product that is cured by heating after being irradiated with active energy rays.

(1) Cationically polymerizable compound A cationically polymerizable compound is a compound or oligomer that undergoes a cationic polymerization reaction and is cured by irradiation with active energy rays (e.g., ultraviolet rays, visible light, electron beams, X-rays, etc.) and heating. It is preferable. Examples of the cationic polymerizable compound include epoxy compounds having one or more epoxy groups in the molecule, oxetane compounds having one or more oxetane rings in the molecule, and vinyl compounds. These cationic polymerizable compounds can be used alone or in combination of two or more. Among these, at least one compound selected from the group consisting of epoxy compounds, oxetane compounds, and vinyl compounds is preferred, and epoxy compounds and oxetane compounds are particularly preferred. Examples of epoxy compounds include alicyclic epoxy compounds, aliphatic epoxy compounds, aromatic epoxy compounds, and hydrogenated epoxy compounds. Group epoxy compounds are preferred. Further, the number of epoxy groups present in the molecule of the epoxy compound may be, for example, one, preferably two or more, particularly two. Using a bifunctional epoxy compound (the number of epoxy groups is 2) has high adhesion to the shrinkage stress of the polarizer, so it is advantageous for forming a polarizing plate with excellent peeling resistance. be.

The alicyclic epoxy compound may be a compound having one or more epoxy groups bonded to an alicyclic ring in the molecule. "Epoxy group bonded to an alicyclic ring" means a 3-membered ring containing an oxygen atom -O- in the following formula (5). In the following formula (5), m may be an integer of 2 to 5.

The alicyclic epoxy compound may be a compound in which a group obtained by removing one or more hydrogen atoms in (CH ₂ ) _m in formula (5) is bonded to another chemical structure. Specifically, in the alicyclic epoxy compound, the hydrogen-removed group in (CH ₂ ) _m in formula (5) is directly or linearly or branched alkylene group (e.g., linear). It is bonded to one or more compounds of formula (5) via a chain or branched C _1-12 alkylene group. Note that -CH ₂ - constituting the linear or branched alkylene group may be substituted with -O- or -CO-. Furthermore, one or more hydrogen atoms in (CH ₂ ) _m may be appropriately substituted with a linear or branched alkyl group such as a methyl group or an ethyl group. Among these, from the viewpoint of adhesiveness and curing speed, alicyclic epoxy compounds having an epoxycyclopentane structure [m=3 in the above formula (5)] and an epoxycyclohexane structure [m=4 in the above formula (5)] is advantageous.

Specific examples of suitable bifunctional alicyclic epoxy compounds (sometimes referred to as bifunctional alicyclic epoxy compounds) are listed below. Here, we will first list the names of the compounds, and then show their corresponding chemical formulas, and the same symbols will be attached to the compound names and their corresponding chemical formulas.

1A: 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate,
2A: 3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclohexanecarboxylate,
3A: ethylene bis(3,4-epoxycyclohexane carboxylate),
4A: bis(3,4-epoxycyclohexylmethyl) adipate,
5A: bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate,
6A: diethylene glycol bis(3,4-epoxycyclohexyl methyl ether),
7A: Ethylene glycol bis(3,4-epoxycyclohexyl methyl ether), 8A: 2,3,14,15-diepoxy-7,11,18,21-tetraoxatrispiro [5.2.2.5.2 .2] Henikosan,
9A: 3-(3,4-epoxycyclohexyl)-8,9-epoxy-1,5-dioxaspiro[5.5]undecane,
10A: 4-vinylcyclohexene dioxide,
11A: limonene dioxide,
12A: bis(2,3-epoxycyclopentyl)ether,
13A: Dicyclopentadiene dioxide.

Examples of aliphatic epoxy compounds include compounds having at least one oxirane ring (3-membered cyclic ether) in the molecule bonded to an aliphatic carbon atom, such as monofunctional aliphatic epoxy compounds (e.g., butyl glycidyl ether, 2 - linear or branched C _2-12 alkyl glycidyl ethers such as ethylhexyl glycidyl ether); difunctional aliphatic epoxy compounds (such as 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether); ethers, linear or branched C _2-12 alkyl diglycidyl ethers such as neopentyl glycol diglycidyl ether, cyclic alkyl diglycidyl ethers such as 1,4-cyclohexanedimethanol diglycidyl ether, preferably linear or (branched C _2-6 alkyl diglycidyl ether, etc.); Tri- or more functional aliphatic epoxy compounds (for example, C _1-12 alkyl glycidyl ether such as trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, etc.); 4 Examples include epoxy compounds having one epoxy group directly bonded to an alicyclic ring and an oxirane ring bonded to an aliphatic carbon atom, such as vinylcyclohexene dioxide and limonene dioxide.
A suitable bifunctional (the number of epoxy groups present in the molecule is 2) aliphatic epoxy compound (sometimes referred to as a bifunctional aliphatic epoxy compound) can be represented by the following formula (6), for example.

In the above formula (6), Y is an alkylene group having 2 to 12 carbon atoms (preferably an alkylene group having 2 to 6 carbon atoms), an alkylene group having 4 to 12 total carbon atoms in which an ether bond is present, or a fatty acid A divalent hydrocarbon group having a ring structure and having 6 to 18 carbon atoms, preferably an alkylene group having 2 to 6 carbon atoms.

The aliphatic diepoxy compound represented by the formula (6) is specifically a diglycidyl ether of an alkanediol, a diglycidyl ether of an oligoalkylene glycol having a repeating number of up to about 4, or a diglycidyl ether of an alicyclic diol. It is.

Specific examples of diols (glycols) that can form the aliphatic diepoxy compound represented by the formula (6) are listed below. Examples of the alkanediol include ethylene glycol, propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4- Butanediol, neopentyl glycol, 3-methyl-2,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4 -Pentanediol, 2,4-diethyl-1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 3,5-heptanediol, 1,8-octanediol, 2-methyl-1 , 8-octanediol, 1,9-nonanediol, etc. Examples of oligoalkylene glycols include diethylene glycol, triethylene glycol, tetraethylene glycol, and dipropylene glycol. Examples of alicyclic diols include cyclohexanediol and cyclohexanedimethanol.
Aromatic epoxy compounds are compounds that have an aromatic ring and an epoxy group in the molecule. Specific examples include bisphenol-type epoxy compounds such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl ether of bisphenol S, or oligomers thereof; phenol novolac epoxy resin, cresol novolac epoxy resin, hydroxyl Novolac-type epoxy resins such as benzaldehydephenol novolac epoxy resin; polyfunctional such as glycidyl ether of 2,2',4,4'-tetrahydroxydiphenylmethane, glycidyl ether of 2,2',4,4'-tetrahydroxybenzophenone, etc. type epoxy compounds; examples include polyfunctional epoxy resins such as epoxidized polyvinylphenol.

The hydrogenated epoxy compound may be a glycidyl ether of a polyol having an alicyclic ring, and is a nuclear water obtained by selectively hydrogenating the aromatic rings of an aromatic polyol under pressure in the presence of a catalyst. The additive polyhydroxy compound may be glycidyl etherified. Specific examples of aromatic polyols include bisphenol-type compounds such as bisphenol A, bisphenol F, and bisphenol S; novolak-type resins such as phenol novolak resin, cresol novolak resin, and hydroxybenzaldehyde phenol novolak resin; tetrahydroxydiphenylmethane and tetrahydroxybenzaldehyde phenol novolak resin; Examples include polyfunctional compounds such as hydroxybenzophenone and polyvinylphenol. A glycidyl ether can be obtained by reacting an alicyclic polyol obtained by hydrogenating the aromatic ring of an aromatic polyol with epichlorohydrin. Among these hydrogenated epoxy compounds, hydrogenated diglycidyl ether of bisphenol A and the like are preferred.

The epoxy equivalent of the epoxy compound may be, for example, 43 to 1500 g/equivalent, preferably 700 to 1000 g/equivalent, more preferably 90 to 500 g/equivalent, particularly 100 to 300 g/equivalent. When the epoxy equivalent is within the above range, a polarizing plate with excellent peeling resistance can be formed.

The proportion of the epoxy compound may be 40 to 100 parts by weight, preferably 60 to 99 parts by weight, more preferably 80 to 98 parts by weight, especially 90 to 97 parts by weight, based on the cationically polymerizable compound. When it is within these ranges, it is advantageous for adhesion (or adhesion). Furthermore, from the viewpoint of optimizing the curing speed and improving adhesion, etc., an alicyclic epoxy compound and an aliphatic epoxy compound can also be used together. In this case, the ratio (mass ratio) of the alicyclic epoxy compound and the aliphatic epoxy compound is, for example, alicyclic epoxy compound/aliphatic epoxy compound=95/5 to 5/95, preferably 90/10 to 10. /90, more preferably 80/20 to 20/80, still more preferably 75/25 to 30/70. When it is within this range, it is advantageous for forming an adhesive layer with high adhesiveness and durability.

The oxetane compound, which is one of the cationic polymerizable compounds, may be a compound containing one or more oxetane rings (oxetanyl group) in the molecule, such as monofunctional oxetane compounds [e.g., 3-ethyl- 3-Hydroxymethyloxetane (sometimes called oxetane alcohol), 2-ethylhexyloxetane, 1,4-bis[{(3-ethyloxetan-3-yl)methoxy}methyl]benzene (sometimes called xylylenebisoxetane) ), 3-ethyl-3-(phenoxymethyl)oxetane, 3-(cyclohexyloxy)methyl-3-ethyloxetane; difunctional oxetane compounds [e.g., 3-ethyl-3[{(3-ethyloxetane-3- yl)methoxy}methyl]oxetane and the like. Among these oxetane compounds, bifunctional oxetane compounds are preferred from the viewpoints of adhesiveness and curing speed. The oxetane compound may be used as the main component of the cationically polymerizable compound, or may be used in combination with an epoxy compound. In particular, it is preferable to use an epoxy compound and an oxetane compound in combination, since it may enhance curability and improve peel resistance, curl resistance, etc. In this case, the proportion of the oxetane compound can be, for example, 0.5 to 70 parts by weight, preferably 1 to 30 parts by weight, and more preferably 3 to 10 parts by weight, based on 100 parts by weight of the epoxy compound. When the proportion of the oxetane compound is below the upper limit, it is advantageous from the viewpoint of adhesion (or adhesion), and when it is above the lower limit, it is advantageous from the perspective of durability against high temperatures and the like.

Vinyl compounds that can be cationic polymerizable compounds include aromatic, aliphatic or alicyclic vinyl ether compounds, specific examples of which include n-amyl vinyl ether, i-amyl vinyl ether, n-hexyl vinyl ether, Vinyl ethers of alkyl or alkenyl alcohols having 5 to 20 carbon atoms such as n-octyl vinyl ether, 2-ethylhexyl vinyl ether, n-dodecyl vinyl ether, stearyl vinyl ether, oleyl vinyl ether; 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 4-hydroxy Hydroxyl group-containing vinyl ethers such as butyl vinyl ether; vinyl ethers of monoalcohols with aliphatic or aromatic rings such as cyclohexyl vinyl ether, 2-methylcyclohexyl vinyl ether, cyclohexylmethyl vinyl ether, and benzyl vinyl ether; glycerol monovinyl ether, 1,4-butanediol mono Vinyl ether, 1,4-butanediol divinyl ether, 1,6-hexanediol divinyl ether, neopentyl glycol divinyl ether, pentaerythritol divinyl ether, pentaerythritol tetravinyl ether, trimethylolpropane divinyl ether, trimethylolpropane trivinyl ether, 1, Mono-polyvinyl ethers of polyhydric alcohols such as 4-dihydroxycyclohexane monovinyl ether, 1,4-dihydroxycyclohexane divinyl ether, 1,4-dihydroxymethylcyclohexane monovinyl ether, 1,4-dihydroxymethylcyclohexane divinyl ether; diethylene glycol divinyl ether; Examples include polyalkylene glycol mono-divinyl ethers such as triethylene glycol divinyl ether and diethylene glycol monobutyl monovinyl ether; other vinyl ethers such as glycidyl vinyl ether and ethylene glycol vinyl ether methacrylate. The vinyl compound may be used as the main component of the cationically polymerizable compound, or may be used in combination with an epoxy compound or an epoxy compound and an oxetane compound. A vinyl compound may be used in combination, since it may lower the viscosity of the adhesive and improve the curing speed.

The cationically polymerizable adhesive may further contain other cationically polymerizable compounds other than those mentioned above, such as a cyclic lactone compound, a cyclic acetal compound, a cyclic thioether compound, and a spiro-orthoester compound.

(2) First acid generator The first acid generator is an ionic compound that has a curing temperature of less than 120°C, generates an acid at a predetermined temperature, and is capable of polymerizing a cationically polymerizable compound. . Here, the "curing temperature" of the present invention refers to the standard substance 3',4'-epoxycyclohexylmethyl-3,4 measured by the method described in the <Measurement of curing temperature> section of Examples. -Differential scanning calorimetry (DSC) of a curable composition prepared by adding 1 part by mass (solid content) of a first acid generator to 100 parts by mass of epoxycyclohexane carboxylate (manufactured by Daicel Corporation, trade name "CEL2021P") ) indicates the temperature at which the amount of heat reaches its maximum. Further, the first acid generator may be curable by active energy rays as long as it has the above properties. That is, a predetermined amount of acid may be generated by irradiating the adhesive with active energy rays.

The curing temperature may be less than 120°C, for example, 50°C to 115°C, preferably 70°C to 110°C, more preferably 90°C to 105°C, especially 95°C to 105°C, preferably may be 95°C to 117°C, more preferably 95°C to 115°C.
If it is within the above range, the cationic polymerizable compound is easily cured, which is advantageous from the viewpoint of durability of the polarizing plate, and since the heating temperature is relatively low, it is also advantageous from the viewpoint of appearance.

［式中、Ｒ^１は置換基を有してもよいＣ_６－１４アリール基又は置換基を有していてもよいＣ_３－１４芳香族複素環基であり、Ｒ^２～Ｒ^４は、互いに独立して、Ｃ_１－１８アルキル基、置換基を有してもよいＣ_６－１４アリール基又は置換基を有していてもよいＣ_３－１４芳香族複素環基であり、前記置換基はＣ_１－１８アルキル基、ハロゲン化Ｃ_１－８アルキル基、Ｃ_２－１８アルケニル基、Ｃ_２－１８アルキニル基、Ｃ_６－１４アリール基、Ｃ_３－１４芳香族複素環基、ニトロ基、水酸基、シアノ基、－ＯＲ^５で表されるアルコキシ基若しくはアリールオキシ基、Ｒ^６ＣＯ－で表されるアシル基、Ｒ^７ＣＯＯ－で表されるアシロキシ基、－ＳＲ^８で表されるアルキルチオ基若しくはアリールチオ基、－ＮＲ^９Ｒ^１０で表されるアミノ基、又はハロゲン原子であり、前記Ｒ^５～Ｒ^８はＣ_１－８アルキル基、Ｃ_６－１４アリール基又はＣ_３－１４芳香族複素環基であり、前記Ｒ^９及びＲ^１０は水素原子、Ｃ_１－８アルキル基、Ｃ_６－１４アリール基又はＣ_３－１４芳香族複素環基である］
又は下記式（２）で表されるアニオンである。

［式中、Ｒｆは水素の８０％以上がフッ素原子で置換された、同一又は異なるアルキル基を示し、ａは１～５の整数である。］ The first acid generator is an ionic compound, and the counter anion constituting the ionic compound is an anion represented by the following formula (1).

[Wherein, R ¹ is a C _6-14 aryl group which may have a substituent or a C _3-14 aromatic heterocyclic group which may have a substituent, and R ² to R ⁴ are independently of each other, they are a C _1-18 alkyl group, a C _6-14 aryl group which may have a substituent, or a C _3-14 aromatic heterocyclic group which may have a substituent; The groups include C _1-18 alkyl group, halogenated C _1-8 alkyl group, C _2-18 alkenyl group, C _2-18 alkynyl group, C _6-14 aryl group, C _3-14 aromatic heterocyclic group, nitro group, hydroxyl group, cyano group, alkoxy group or aryloxy group represented by -OR ⁵ , acyl group represented by R ⁶ CO-, acyloxy group represented by R ⁷ COO-, represented by -SR ⁸ An alkylthio group or an arylthio group, an amino group represented by -NR ⁹ R ¹⁰ , or a halogen atom, and R ⁵ to R ⁸ are a C _1-8 alkyl group, a C _6-14 aryl group, or a C _3-14 aromatic group. and R ⁹ and R ¹⁰ are a hydrogen atom, a C _1-8 alkyl group, a C _6-14 aryl group, or a C _3-14 aromatic heterocyclic group]
Or it is an anion represented by the following formula (2).

[In the formula, Rf represents the same or different alkyl group in which 80% or more of hydrogen atoms are substituted with fluorine atoms, and a is an integer from 1 to 5. ]

In R ² to R ⁴ of the formula (1), examples of the C _1-18 alkyl group include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-octyl, n-decyl, n- Straight chain C _1-18 alkyl groups, preferably straight chain C _1-18 alkyl groups such as dodecyl, n-tetradecyl; isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl, tert-pentyl, isohexyl , 2-ethylhexyl and 1,1,3,3-tetramethylbutyl, preferably branched C _1-18 alkyl groups; cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl _, etc. Examples include C _3-18 cycloalkyl groups, preferably C _3-8 cycloalkyl groups; bridged cyclic alkyl groups such as norbornyl, adamantyl, and pinanyl.

In R ¹ to R ⁴ of the formula (1), the C _6-14 aryl group includes, for example, a monocyclic C _6-14 aryl group such as phenyl; naphthyl, anthracenyl, phenanthrenyl, anthraquinolyl, fluorenyl, naphthoquinolyl, etc. Examples include fused polycyclic C _6-14 aryl groups.
In R ¹ to R ⁴ of the formula (1), the C _3-14 aromatic heterocyclic group is a monocyclic C _3- such as thienyl, furanyl, pyranyl, pyrrolyl, oxazolyl, thiazolyl, pyridyl, pyrimidyl, pyrazinyl, etc. ₁₄ heterocycle; indolyl, benzofuranyl, isobenzofuranyl, benzothienyl, isobenzothienyl, quinolyl, isoquinolyl, quinoxalinyl, quinazolinyl, carbazolyl, acridinyl, phenothiazinyl, phenazinyl, xanthenyl, thianthrenyl, phenoxazinyl, phenoxathiinyl, chromanyl, Examples include C _3-14 aromatic heterocyclic hydrocarbons such as fused polycyclic C _6-14 heterocycles such as isochromanyl, coumarinyl, dibenzothienyl, xanthonyl, thioxanthonyl, and dibenzofuranyl. The C _3-14 aromatic heterocyclic group may be a monovalent group formed from a monocyclic C _3-5 heterocycle, or a monovalent group formed from a monocyclic C _6-14 heterocycle. It may also be a value group.

Furthermore, the C _6-14 aryl group or C _3-14 aromatic heterocyclic group in R ¹ to R ⁴ of the formula (1) has a substituent (sometimes referred to as substituent (A)). Good too. In addition, as the C _1-8 alkyl group, C _6-14 aryl group, and C _3-14 aromatic heterocyclic group of R ⁵ to R ¹⁰ , the C _1-8 alkyl group illustrated in R ¹ to R ⁴ above, Examples include a C _6-14 aryl group or a C _3-14 aromatic heterocyclic group.

Examples of the substituent (A) include a C _1-18 alkyl group [for example, the above-exemplified C _1-18 alkyl group]; a halogenated C _1-8 alkyl group [for example, trifluoromethyl, trichloromethyl, penta- Fluoroethyl, 2,2,2-trichloroethyl, 2,2,2-trifluoroethyl, 1,1-difluoroethyl, heptafluoro-n-propyl, 1,1-difluoro-n-propyl, 3,3, Direct halogenated substances such as 3-trifluoro-n-propyl, nonafluoro-n-butyl, 3,3,4,4,4-pentafluoro-n-butyl, perfluoro-n-pentyl, perfluoro-n-octyl, etc. Chained C _1-8 alkyl group; halogenated branched C _1-8 alkyl group such as hexafluoroisopropyl, hexachloroisopropyl, hexafluoroisobutyl, nonafluoro-tert-butyl; pentafluorocyclopropyl, nonafluorocyclobutyl, perfluorocyclobutyl, etc. halogenated C _3-8 cycloalkyl group such as fluorocyclopentyl, perfluorocyclohexyl]; C _7-12 halogenated bridged cyclic alkyl group such as perfluoroadamantyl; C _2-18 alkenyl group [e.g. vinyl, allyl , 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-methyl-1-propenyl, 1-methyl-2-propenyl, 2-methyl-1-propenyl and 2-methyl-2 - Straight or branched C _2-18 alkenyl groups such as propenyl; C _2-18 cycloalkenyl groups such as 2-cyclohexenyl and 3-cyclohexenyl; C _2-18 arylalkenyl such as styryl and cinnamyl groups]; C _2-18 alkynyl groups [e.g., ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 3-butynyl, 1-methyl-2-propynyl, 1,1-dimethyl -2-propynyl, 1-pentynyl, 2-pentynyl, 3-pentynyl, 4-pentynyl, 1-methyl-2-butynyl, 3-methyl-1-butynyl, 1-decynyl, 2-decynyl, 8-decynyl, Straight chain or branched C _2-18 alkynyl groups such as 1-dodecynyl, 2-dodecynyl and 10-dodecynyl; C _2-18 arylalkynyl groups such as phenylethynyl]; C _6-14 aryl groups [e.g. Aryl group shown above]; C _3-14 aromatic heterocyclic group [e.g. aromatic heterocyclic group shown above]; Nitro group; hydroxyl group; cyano group; alkoxy group represented by -OR ⁵ [e.g. , methoxy, ethoxy, n-propoxy, iso-propoxy, n-butoxy, sec-butoxy, tert-butoxy, n-pentoxy, iso-pentoxy, neo-pentoxy, C _1-8 alkoxy groups such as 2-methylbutoxy, etc. ]; -Aryloxy group represented by OR ⁵ [C _6-14 aryloxy group such as phenoxy, naphthoxy, etc.]; -Acyl group represented by COR ⁶ [e.g., acetyl, propanoyl, butanoyl, pivaloyl, benzoyl, etc. a C _1-8 alkyl-carbonyl group or a C _6-14 aryl-carbonyl group]; an acyloxy group represented by -COOR ⁷ [for example, a C _1-8 alkyl-carbonyl group such as acetoxy, butanoyloxy, benzoyloxy, etc.]; oxy group or C _6-14 aryl-carbonyloxy group]; -SR ⁸ alkylthio group [e.g., C _1-8 alkylthio group such as methylthio, ethylthio, butylthio, hexylthio, cyclohexylthio, etc.], -SR Arylthio group represented by ⁸ [e.g., C _6-14 arylthio group such as phenylthio, naphthylthio, etc.]; -NR ⁹ Amino group represented by R ¹⁰ [e.g., methylamino, ethylamino, propylamino, dimethylamino, amino groups such as diethylamino, methylethylamino, dipropylamino, dipropylamino, piperidino, etc.]; halogen atoms [e.g., fluorine atom, chlorine atom, bromine atom, iodine atom], and the like.

Among these substituents (A), halogenated C _1-8 alkyl groups, halogen atoms, nitro groups, cyano groups, etc. are preferred. In particular, from the viewpoint of polymerizability and curability of the cationic polymerizable compound, a fluorine atom and a fluorinated C _1-8 alkyl group are preferred.

R ¹ is preferably a C _6-14 aryl group which may have a substituent, and is a C _6-14 aryl group which may have a halogen atom or a halogenated C _1-8 alkyl group. It is more preferable that there be.
It is preferable that R ² and R ³ are each independently a C _6-14 aryl group which may have a substituent, and even if it has a halogen atom or a halogenated C _1-8 alkyl group. More preferably, it is a C _6-14 aryl group.
R ⁴ is preferably a C _1-18 alkyl group or a C _6-14 aryl group which may have a substituent.

R ² and R ³ are preferably the same group, R ¹ to R ³ are more preferably the same group, and even more preferably R ¹ to R ⁴ are all the same group.

Preferred embodiments of the counter anion in the formula (1) include, for example, an anion in which R ¹ to R ⁴ are each a pentafluorophenyl group; R ¹ to R ⁴ are each a 3,5-bis(trifluoromethyl)phenyl group; Anion in which R ¹ to R ⁴ are each a 3,4,5-trifluorophenyl group; Anion in which R ¹ to R ³ are each a tetrafluorophenyl group and R ⁴ is a phenyl group; R ¹ to Examples include anions in which R ³ is a tetrafluorophenyl group and R ⁴ is a butyl group.

In the formula (2), examples of the alkyl group of Rf include the alkyl groups listed above. In particular, C _1-8 alkyl groups such as methyl, ethyl, propyl and butyl are preferred. In formula (2), a is an integer of 1 to 5, preferably 2 to 4.

The counter cation constituting the first acid generator of the present invention is, for example, a sulfonium (for example, a triarylsulfonium cation such as a triphenylsulfonium cation or a 4,4'-bis(diphenylsulfonio)diphenylsulfide cation), These include iodonium (eg, diaryliodonium cations such as diphenyliodonium cations), diazonium (eg, benzenediazonium cations), oxonium, ammonium, phosphonium, and the like. Among these, from the viewpoint of polymerization reactivity, sulfonium and iodonium are preferred, and sulfonium is particularly preferred.

Since the first acid generator of the present invention has an anion represented by formula (1) or (2) whose conjugate acid has relatively high acidity as a counter anion, the cationically polymerizable compound is cured by heating. It is possible to form a polarizing plate with excellent peeling resistance and deterioration resistance even under high temperature and high humidity conditions. In particular, the anion represented by formula (1) can effectively promote curing. Furthermore, the anion represented by formula (1) or (2) is more suitable in terms of safety than antimonate anions (eg, SbF ₆ ⁻ ).

［式中、Ｒ^１１及びＲ^１２は互いに独立して、アルキル基、アラルキル基、アリール基又は芳香族複素環基を示し、Ｒ^１３は置換基を有してもよいフェニル基を示し、Ｘ^－は、前記式（１）又は前記式（２）で表されるアニオンである］ A preferred embodiment of the first acid generator of the present invention includes an ionic compound represented by the following formula (3).

[In the formula, R ¹¹ and R ¹² independently represent an alkyl group, an aralkyl group, an aryl group, or an aromatic heterocyclic group, R ¹³ represents a phenyl group which may have a substituent, and X ^- is an anion represented by the above formula (1) or the above formula (2)]

In R ¹¹ and R ¹² of the formula (3), examples of the alkyl group include the alkyl groups exemplified in R ² to R ⁴ , and examples of the aralkyl group include benzyl, 2-methylbenzyl, Examples include C _6-10 aryl C _1-8 alkyl groups such as 1-naphthylmethyl and 2-naphthylmethyl, and examples of the aryl group include the aryl groups exemplified in R ¹ to R ⁴ above. Examples of the aromatic heterocyclic group include the aromatic heterocyclic groups exemplified in R ¹ to R ⁴ above. The phenyl group in R ¹³ may be substituted with a substituent (B).
The alkyl group for R ¹¹ and R ¹² is preferably a C _1-8 alkyl group such as methyl, ethyl, propyl, butyl or pentyl, and more preferably a C _1-4 alkyl group. The aralkyl group for R ¹¹ and R ¹² is preferably benzyl or naphthylbenzyl, and the aryl group for R ¹¹ or R ¹² is preferably a phenyl group or a naphthyl group.

Examples of the substituent (B) include alkoxy groups [for example, straight-chain groups such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy, hexyloxy, decyloxy, dodecyloxy, and octadecyloxy; Aryl group [e.g., C _6-10 aryl group such as phenyl, tolyl, dimethylphenyl, naphthyl, _{C 1-5 alkyl} C _6-10 aryl group, etc.]; Aromatic heterocyclic group (C _3-14 aromatic heterocyclic group such as thienyl, furanyl, pyrrolyl, indolyl, etc.); Aryloxy group [e.g., C _6-10 aryloxy group such as phenoxy, naphthyloxy, etc.]; Alkylcarbonyl groups [such as C _2-18 alkylcarbonyl groups such as acetyl, propionyl, butanoyl, 2-methylpropionyl, heptanoyl, 2-methylbutanoyl, 3-methylbutanoyl, octanoyl, decanoyl, dodecanoyl and octadecanoyl]; Arylcarbonyl group [for example, _C7-11 arylcarbonyl group such as benzoyl, naphthoyl, etc.]; Aralkylcarbonyl group [for example, C7-11 arylcarbonyl group such as benzylcarbonyl, 2-methylbenzylcarbonyl, 1-naphthylmethylcarbonyl, 2-naphthylmethylcarbonyl, etc.] _6-10 aryl C _1-8 alkyl-carbonyl group, etc.]; alkoxycarbonyl group [e.g., methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, isopropoxycarbonyl, butoxycarbonyl, isobutoxycarbonyl, sec-butoxycarbonyl, tert-butoxycarbonyl , octyloxycarbonyl, tetradecyloxycarbonyl, linear or branched C _2-19 alkoxycarbonyl groups such as octadecyloxycarbonyl]; Aryloxycarbonyl group [C _7-11 such as phenoxycarbonyl and naphthoxycarbonyl, etc.]; aryloxycarbonyl group, etc.).

In addition, as the substituent (B), for example, an aralkyloxycarbonyl group [for example, C _6-10 aryl such as benzyloxycarbonyl, 2-methylbenzyloxycarbonyl, 1-naphthylmethyloxycarbonyl, 2-naphthylmethyloxycarbonyl, etc. C _1-8 alkoxy-carbonyl group; alkylcarbonyloxy group [e.g., acetoxy, ethylcarbonyloxy, propylcarbonyloxy, isopropylcarbonyloxy, butylcarbonyloxy, isobutylcarbonyloxy, sec-butylcarbonyloxy, tert-butylcarbonyloxy, C _2-19 alkylcarbonyloxy groups such as octylcarbonyloxy, tetradecylcarbonyloxy, octadecylcarbonyloxy, etc.]; Arylcarbonyloxy groups [e.g., C _7-11 arylcarbonyloxy groups such as benzoyloxy, naphthoyloxy, etc. ], aralkylcarbonyloxy group [for example, C _6-10 aryl C _1-8 alkyl-carbonyl group such as benzylcarbonyloxy, 2-methylbenzylcarbonyloxy, 1-naphthylmethylcarbonyloxy, 2-naphthylmethylcarbonyloxy, etc.] , alkoxycarbonyloxy group [e.g., methoxycarbonyloxy, ethoxycarbonyloxy, propoxycarbonyloxy, isopropoxycarbonyloxy, butoxycarbonyloxy, isobutoxycarbonyloxy, sec-butoxycarbonyloxy, tert-butoxycarbonyloxy, octyloxycarbonyloxy , tetradecyloxycarbonyloxy and octadecyloxycarbonyloxy, straight-chain or branched C _2-19 alkoxycarbonyloxy groups]; aryloxycarbonyloxy groups [such as phenoxycarbonyloxy and naphthoxycarbonyloxy, etc.]; C _7-11 aryloxycarbonyloxy group, etc.]; aralkyloxycarbonyloxy group [e.g., benzyloxycarbonyloxy, 2-methylbenzyloxycarbonyloxy, 1-naphthylmethyloxycarbonyloxy, 2-naphthylmethyloxycarbonyloxy, etc. C _6-10 aryl C _1-8 alkoxy-carbonyloxy group, etc.]; Arylthiocarbonyl group [e.g., C _7-11 arylthiocarbonyl group such as phenylthiocarbonyl and naphthoxythiocarbonyl]; Arylthio group [e.g. , phenylthio, 2-methylphenylthio, 3-methylphenylthio, 4-methylphenylthio, 2-chlorophenylthio, 3-chlorophenylthio, 4-chlorophenylthio, 2-bromophenylthio, 3-bromophenylthio, 4- Bromophenylthio, 2-fluorophenylthio, 3-fluorophenylthio, 4-fluorophenylthio, 2-hydroxyphenylthio, 4-hydroxyphenylthio, 2-methoxyphenylthio, 4-methoxyphenylthio, 1-naphthylthio, 2-naphthylthio, 4-[4-(phenylthio)benzoyl]phenylthio, 4-[4-(phenylthio)phenoxy]phenylthio, 4-[4-(phenylthio)phenyl]phenylthio, 4-(phenylthio)phenylthio, 4-benzoyl Phenylthio, 4-benzoyl-2-chlorophenylthio, 4-benzoyl-3-chlorophenylthio, 4-benzoyl-3-methylthiophenylthio, 4-benzoyl-2-methylthiophenylthio, 4-(4-methylthiobenzoyl)phenylthio , 4-(2-methylthiobenzoyl)phenylthio, 4-(p-methylbenzoyl)phenylthio, 4-(p-ethylbenzoyl)phenylthio 4-(p-isopropylbenzoyl)phenylthio, 4-(p-tert-butylbenzoyl) C _6-20 arylthio groups such as phenylthio]; alkylthio groups [e.g., methylthio, ethylthio, propylthio, isopropylthio, butylthio, isobutylthio, sec-butylthio, tert-butylthio, pentylthio, isopentylthio, neopentylthio, tert - linear or branched C _1-18 alkylthio groups such as pentylthio, octylthio, decylthio, dodecylthio, isooctadecylthio, etc.].

Furthermore, as the substituent (B), heterocyclic hydrocarbon groups [for example, thienyl, furanyl, pyranyl, pyrrolyl, oxazolyl, thiazolyl, pyridyl, pyrimidyl, pyrazinyl, indolyl, benzofuranyl, benzothienyl, quinolyl, isoquinolyl, quinoxalinyl, C _3-20 aryl heterocyclic hydrocarbon groups such as quinazolinyl, carbazolyl, acridinyl, phenothiazinyl, phenazinyl, xanthenyl, thianthrenyl, phenoxazinyl, phenoxathiinyl, chromanyl, isochromanyl, dibenzothienyl, xanthonyl, thioxanthonyl and dibenzofuranyl ( aromatic heterocyclic group); Alkylsulfinyl group [e.g., methylsulfinyl, ethylsulfinyl, propylsulfinyl, isopropylsulfinyl, butylsulfinyl, isobutylsulfinyl, sec-butylsulfinyl, tert-butylsulfinyl, pentylsulfinyl, isopentylsulfinyl, Linear or branched C _1-18 alkylsulfinyl groups such as neopentylsulfinyl, tert-pentylsulfinyl, octylsulfinyl and iso-octadecylsulfinyl]; Arylsulfinyl groups [such as phenylsulfinyl, tolylsulfinyl and naphthylsulfinyl, etc.]; C _6-10 arylfulfinyl group, etc.]; Alkylsulfonyl group [e.g., methylsulfonyl, ethylsulfonyl, propylsulfonyl, isopropylsulfonyl, butylsulfonyl, isobutylsulfonyl, sec-butylsulfonyl, tert-butylsulfonyl, pentylsulfonyl, iso Straight chain or branched C _1-18 alkylsulfonyl groups such as pentylsulfonyl, neopentylsulfonyl, tert-pentylsulfonyl, octylsulfonyl, octadecylsulfonyl, etc.]; Arylsulfonyl group [for example, phenylsulfonyl, tolylsulfonyl (tosyl group) and C _6-10 arylsulfonyl groups such as naphthylsulfonyl]; hydroxy(poly)alkyleneoxy groups [e.g., hydroxy(poly)alkyleneoxy groups in which the alkyleneoxy group has 1 to 6 repeating units]; amino groups [For example, methylamino, dimethylamino, ethylamino, methylethylamino, diethylamino, n-propylamino, methyl-n-propylamino, ethyl-n-propylamino, n-propylamino, isopropylamino, isopropylmethylamino, isopropyl Substituted amino groups and amino groups having 1 to 15 carbon atoms such as ethylamino, diisopropylamino, phenylamino, diphenylamino, methylphenylamino, ethylphenylamino, n-propylphenylamino and isopropylphenylamino]; halogen atoms (e.g. , fluorine atom, chlorine atom, bromine atom, iodine atom), hydroxyl group, etc.
Note that preferable examples of X ⁻ include preferable embodiments of the anion represented by the above formula (1) or (2).

Specific examples of the first acid generator represented by formula (3) include phenyldimethylsulfonium tetrakis(pentafluorophenyl)borate, 4-hydroxyphenyldimethylsulfonium tetrakis(pentafluorophenyl)borate, 4- Methoxycarbonyloxyphenyldimethylsulfonium tetrakis(pentafluorophenyl)borate, 4-acetoxyphenyldimethylsulfonium tetrakis(pentafluorophenyl)borate, 4-benzyloxycarbonyloxyphenyldimethylsulfonium tetrakis(pentafluorophenyl)borate, Phenyl-methyl-benzyl Sulfonium tetrakis(pentafluorophenyl)borate, 4-hydroxyphenyl-methyl-benzylsulfonium tetrakis(pentafluorophenyl)borate, 4-methoxycarbonyloxyphenyl-methyl-benzylsulfonium tetrakis(pentafluorophenyl)borate, 4-acetoxyphenyl- Methyl-benzylsulfonium tetrakis(pentafluorophenyl)borate, 4-benzyloxycarbonyloxyphenyl-methyl-benzylsulfonium tetrakis(pentafluorophenyl)borate, phenyl-methyl-2-methylbenzylsulfonium tetrakis(pentafluorophenyl)borate, 4 -Hydroxyphenyl-methyl-2-methylbenzylsulfonium tetrakis(pentafluorophenyl)borate, 4-methoxycarbonyloxyphenyl-methyl-2-methylbenzylsulfonium tetrakis(pentafluorophenyl)borate, 4-acetoxyphenyl-methyl-2- Methylbenzylsulfonium tetrakis(pentafluorophenyl)borate, 4-benzyloxycarbonyloxyphenyl-methyl-2-methylbenzylsulfonium tetrakis(pentafluorophenyl)borate, phenyl-methyl-1-naphthylmethylsulfonium tetrakis(pentafluorophenyl)borate , 4-hydroxyphenyl-methyl-1-naphthylmethylsulfonium tetrakis(pentafluorophenyl)borate, 4-hydroxyphenyl-methyl-2-naphthylmethylsulfonium tetrakis(pentafluorophenyl)borate, 4-methoxycarbonyloxyphenyl-methyl- 1-Naphthylmethylsulfonium tetrakis(pentafluorophenyl)borate, 4-acetoxyphenyl-methyl-1-naphthylmethylsulfonium tetrakis(pentafluorophenyl)borate, 4-benzyloxycarbonyloxyphenyl-methyl-1-naphthylmethylsulfonium tetrakis( pentafluorophenyl)borate; ionic compounds in which tetrakis(pentafluorophenyl)borate, which is the counter anion of these first acid generators, is replaced with tris(pentafluoroethyl)trifluorophosphate; and the like. These first acid generators can be used alone or in combination of two or more.

(3) Second acid generator The second acid generator generates an acid by irradiation with active energy rays (for example, ultraviolet rays, visible light, electron beams, X-rays, etc.) and converts the cationic polymerizable compound into It is an ionic compound that can be polymerized. The second acid generator has high thermal stability, and the curing temperature is 120°C or higher, for example, 120 to 350°C, preferably 150 to 350°C, more preferably 200 to 320°C, even more preferably 250 to 300°C. It may be ℃. The definition of curing temperature is the same as that for the first acid generator, and it is measured by the method described in the section <Measurement of curing temperature> in Examples.

The counter anion constituting the second acid generator is not particularly limited as long as the curing temperature of the second acid generator is 120° C. or higher, and includes CF ₃ SO ₃ ^- , C ₄ F ₉ SO ₃ ^- , CH An anion represented by R-SO ₃ ^- such as ₃ SO ₃ ^- (R represents an alkyl group having 1 to 6 carbon atoms or a fluorinated alkyl group having 1 to 6 carbon atoms), an anion represented by the above formula (1) An anion represented by the above formula (2), SbF ₆ ^- or PF ₆ ^- . Among these, from the viewpoint of curability, the anion represented by the above formula (1), the anion represented by the above formula (2), or PF ₆ ^- is preferable. These anions are preferable in terms of safety compared to antimonate anions (eg, SbF ₆ ⁻ ) and the like. Further, the counter anion of the second acid generator may be the same as or different from the counter anion of the first acid generator.
For example, the anion of the second acid generator may be an anion represented by the above formula (1) or (2), and the anion of the first acid generator may be PF ₆ ^- .

Further, the counter cation constituting the second acid generator may be, for example, sulfonium, iodonium (for example, diaryliodonium cation such as diphenyliodonium cation), as long as the curing temperature of the second acid generator is 120° C. or higher. , diazonium (such as the benzenediazonium cation), oxonium, ammonium, phosphonium, and the like. Among these, sulfonium and iodonium are preferred from the viewpoint of polymerization reactivity and curability, and sulfonium is particularly preferred since it provides good thermal stability of the adhesive.

In terms of adhesive curability, the second acid generator of the present invention preferably has ultraviolet absorption characteristics in a wavelength region around 300 nm, and more preferably exhibits maximum absorption around 300 nm.

［式中、Ｒ^１４及びＲ^１５は互いに独立して、アルキル基、アラルキル基、アリール基又は芳香族複素環基を示し、Ｒ^１６は置換基を有してもよいフェニル基を示し、Ｙ^－は、前記式（１）又は前記式（２）で表されるアニオン又はＰＦ_６ ^－である］
Ｒ^１４及びＲ^１５において、アルキル基、アラルキル基、アリール基又は芳香族複素環基としては、前述したＲ^１１及びＲ^１２に例示のアルキル基、アラルキル基、アリール基又は芳香族複素環基などが例示できる。Ｒ^１４及びＲ^１５は、それぞれ独立して、フェニル基、ナフチル基などのアリール基が好ましい。
Ｒ^１６はフェニル基であり、このフェニル基は置換基（Ｃ）を有してもよい。置換基（Ｃ）としては、例えば、置換基（Ｂ）に例示の基が挙げられ、特にアリールチオ基などが好ましい。
好ましいＹ^－としては、前記式（１）若しくは（２）で表される好ましい態様又はＰＦ_６ ^－などが挙げられ、特にＰＦ_６ ^－又は式（２）で表されるアニオンであることが好ましい。 A preferred embodiment of the second acid generator includes an ionic compound represented by the following formula (4).

[In the formula, R ¹⁴ and R ¹⁵ independently represent an alkyl group, an aralkyl group, an aryl group, or an aromatic heterocyclic group, R ¹⁶ represents a phenyl group which may have a substituent, and Y ⁻ is an anion represented by the above formula (1) or the above formula (2) or PF ₆ ^- ]
Examples of the alkyl group, aralkyl group, aryl group, or aromatic heterocyclic group in R ¹⁴ and R ¹⁵ include the alkyl group, aralkyl group, aryl group, or aromatic heterocyclic group exemplified in R ¹¹ and R ¹² described above. I can give an example. R ¹⁴ and R ¹⁵ are each independently preferably an aryl group such as a phenyl group or a naphthyl group.
R ¹⁶ is a phenyl group, and this phenyl group may have a substituent (C). Examples of the substituent (C) include the groups exemplified for the substituent (B), with an arylthio group being particularly preferred.
Preferred examples of Y ^- include the preferred embodiments represented by formula (1) or (2) above, PF ₆ ^- , and the like, with PF ₆ ^- or an anion represented by formula (2) being particularly preferred.

The second acid generator may be a commercially available product. Commercial products of the second acid generator include, for example, Kayarad PCI-220 (manufactured by Nippon Kayaku Co., Ltd.), Kayarad PCI-620 (manufactured by Nippon Kayaku Co., Ltd.), and UVI-6990 (manufactured by Union Carbide Co., Ltd.). ), ADEKA Optomer SP-150 (manufactured by ADEKA Co., Ltd.), ADEKA Optomer SP-170 (manufactured by ADEKA Co., Ltd.), CI-5102 (manufactured by Nippon Soda Co., Ltd.), CIT-1370 (manufactured by Nippon Soda Co., Ltd.) ), CIT-1682 (manufactured by Nippon Soda Co., Ltd.), CIP-1866S (manufactured by Nippon Soda Co., Ltd.), CIP-2048S (manufactured by Nippon Soda Co., Ltd.), CIP-2064S (manufactured by Nippon Soda Co., Ltd.) ), DPI-101 (manufactured by Midori Kagaku Co., Ltd.), DPI-102 (manufactured by Midori Kagaku Co., Ltd.), DPI-103 (manufactured by Midori Kagaku Co., Ltd.), DPI-105 (manufactured by Midori Kagaku Co., Ltd.), MPI-103 (manufactured by Midori Kagaku Co., Ltd.), MPI-105 (manufactured by Midori Kagaku Co., Ltd.), BBI-101 (manufactured by Midori Kagaku Co., Ltd.), BBI-102 (manufactured by Midori Kagaku Co., Ltd.), BBI- 103 (Midori Kagaku Co., Ltd.), BBI-105 (Midori Kagaku Co., Ltd.), TPS-101 (Midori Kagaku Co., Ltd.), TPS-102 (Midori Kagaku Co., Ltd.), TPS-103 ( Midori Kagaku Co., Ltd.), TPS-105 (Midori Kagaku Co., Ltd.), MDS-103 (Midori Kagaku Co., Ltd.), MDS-105 (Midori Kagaku Co., Ltd.), DTS-102 (Midori Kagaku Co., Ltd.) (manufactured by Sun-Apro Co., Ltd.), DTS-103 (manufactured by Midori Kagaku Co., Ltd.), PI-2074 (manufactured by Rhodia), CPI-100P (manufactured by Sun-Apro Co., Ltd.), CPI-101A (manufactured by Sun-Apro Co., Ltd.), CPI Examples include -200K (manufactured by San-Apro Co., Ltd.) and CPI-210S (manufactured by San-Apro Co., Ltd.).

The first acid generator and the second acid generator may be a solution dissolved in a solvent that does not inhibit polymerization or the like. Examples of the solvent include aromatic hydrocarbons [e.g. toluene, xylene, etc.]; carbonates [e.g. propylene carbonate, ethylene carbonate, 1,2-butylene carbonate, dimethyl carbonate, diethyl carbonate, etc.]; ketones [e.g. , acetone, methyl ethyl ketone, methyl isoamyl ketone, chain ketones such as 2-heptanone, cyclic ketones such as cyclohexanone]; ethers [e.g. cyclic ethers such as dioxane]; esters [e.g. methyl acetate, acetic acid ethyl, butyl acetate, etc.]; polyhydric alcohols and derivatives thereof [e.g., ethylene glycol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoacetate, propylene glycol, propylene glycol monoacetate, etc.].

The proportion of the solvent is, for example, about 0.1 to 10 parts by weight, preferably about 0.5 to 5 parts by weight, per 1 part by weight of the first acid generator or the second acid generator.

In the adhesive, the ratio of the total amount of the first acid generator and the second acid generator is, for example, 0.1 to 30 parts by mass, preferably 0.2 to 30 parts by mass, based on 100 parts by mass of the cationically polymerizable compound. It may be 20 parts by weight, more preferably 0.5 to 10 parts by weight, even more preferably 1 to 5 parts by weight, especially 2 to 4 parts by weight. When the total amount of the first acid generator and the second acid generator is equal to or greater than the above lower limit, curing of the adhesive can be sufficiently progressed, and durability and adhesiveness can be improved. On the other hand, when the total amount of the first acid generator and the second acid generator is less than or equal to the above upper limit, yellowing of the polarizing plate when the polarizing plate is heated can be effectively suppressed.

Further, the ratio (mass ratio) of the first acid generator and the second acid generator is, for example, first acid generator/second acid generator (mass ratio) = 95/5 to 5/ 95, preferably 90/10 to 10/90, more preferably 80/20 to 20/80, even more preferably 75/25 to 25/75, particularly preferably 70/30 to 30/70, especially 60/40 to It may be 40/60. Within this range, the cationic polymerizable compound can be effectively cured and a polarizing plate with excellent durability can be formed. Further, from the viewpoint of durability, the second acid generator is preferably contained in the same amount or more than the first acid generator, and more preferably contained in a larger amount than the first acid generator. preferable.

The first acid generator may be used alone or in combination of two or more different types. Further, the second acid generator may be used alone or in combination of two or more different types.

(4) Additives The adhesive forming the adhesive layer may contain additives, if necessary. Examples of additives include ion trapping agents (e.g., inorganic compounds such as powdered bismuth, antimony, magnesium, aluminum, calcium, titanium, and mixtures thereof), antioxidants (e.g., hinderers, etc.). dophenol antioxidants, etc.), chain transfer agents, polymerization accelerators (polyols, etc.), sensitizers, sensitization aids, light stabilizers, tackifiers, thermoplastic resins, fillers, flow regulators, plasticizers agent, antifoaming agent, leveling agent, silane coupling agent, dye, antistatic agent, ultraviolet absorber, etc.
The adhesive layer of the present invention has high adhesion between the protective film and the polarizer even when placed under high temperature and high humidity, and has excellent peeling resistance. That is, the peeling force (adhesion force) of the adhesive layer may be, for example, 1.2 to 3, preferably 1.5 to 2.5 at a gripping movement speed of 300 mm/min. Note that the peeling force (adhesion force) can be measured by the method described in Examples.
The adhesive can be prepared by mixing at least the cationically polymerizable compound, the first acid generator, and the second acid generator by a conventional method.

The adhesive layer preferably has a storage modulus of 600 MPa or more at 80°C. When the storage modulus is 600 MPa or more, dimensional changes of the polarizing plate when the polarizing plate is placed in a high-temperature environment can be suppressed, and the polarizer can be used in durability tests that involve rapid temperature changes such as thermal shock tests. can suppress cracking. The storage modulus at 80° C. is more preferably 800 MPa or more, still more preferably 1000 MPa or more.

A polarizing plate including an adhesive layer of the present invention has excellent adhesion and adhesion between a polarizer and a protective film, and can effectively suppress peeling or lifting of the interface even if strong shrinkage stress occurs in the polarizer. Furthermore, even under high temperature or high temperature and high humidity conditions, deterioration of optical properties (for example, changes in transmittance of a polarizing plate, etc.) can be suppressed. In addition, when using a polarizing plate in the form of a sheet, the polarizer and protective film are less likely to peel off even when cut out from a long object or from a winding roll, and the plate after processing is The leaves do not easily warp. Therefore, the polarizing plate of the present invention has excellent durability even under harsh conditions such as high temperature and high humidity, and is therefore useful as a polarizing plate in liquid crystal display devices and the like.

[2] Polarizer A polarizer is a film that has the function of selectively transmitting linearly polarized light in one direction from natural light. For example, iodine-based polarizers in which iodine is adsorbed and oriented on a polyvinyl alcohol-based resin film, dye-based polarizers in which dichroic dyes are adsorbed and oriented on a polyvinyl alcohol-based resin film, and dichroic dyes in a lyotropic liquid crystal state. Examples include coated polarizers coated with oriented and fixed. These polarizers are called absorption polarizers because they selectively transmit linearly polarized light in one direction from natural light and absorb linearly polarized light in the other direction. Polarizers are not limited to absorptive polarizers, but may also include reflective polarizers that selectively transmit linearly polarized light in one direction from natural light and reflect linearly polarized light in the other direction, or reflective polarizers that selectively transmit linearly polarized light in one direction from natural light. Although a scattering type polarizer may be used, an absorption type polarizer is preferable from the viewpoint of excellent visibility. Among these, iodine-based polarizers are more preferable because they have excellent polarization degree and transmittance.

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

The saponification degree of polyvinyl alcohol resin is usually about 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes can also be used. The average degree of polymerization of the polyvinyl alcohol resin is usually about 1,000 to 10,000, preferably about 1,500 to 5,000. The average degree of polymerization of polyvinyl alcohol resin can be determined in accordance with JIS K 6726.

A film formed from such a polyvinyl alcohol resin is used as an original film of a polarizer. The method of forming a polyvinyl alcohol resin into a film is not particularly limited, and any known method may be employed. The thickness of the polyvinyl alcohol base film is, for example, 150 μm or less, preferably 100 μm or less (for example, 50 μm or less).

A polarizer is produced by a process of uniaxially stretching a polyvinyl alcohol resin film; a process of dyeing the polyvinyl alcohol resin film with a dichroic dye to adsorb the dichroic dye; It can be produced by a method including a step of treating a resin film with an aqueous boric acid solution (crosslinking treatment); and a step of washing with water after the treatment with an aqueous boric acid solution.

The uniaxial stretching of the polyvinyl alcohol resin film can be performed before, simultaneously with, or after dyeing with the dichroic dye. When uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before or during boric acid treatment. Further, uniaxial stretching may be performed in these plural steps.

In the uniaxial stretching, it may be uniaxially stretched between rolls having different circumferential speeds, or it may be uniaxially stretched using hot rolls. Further, the uniaxial stretching may be dry stretching in which the film is stretched in the atmosphere, or wet stretching in which the polyvinyl alcohol resin film is stretched in a swollen state using a solvent or water. The stretching ratio is usually about 3 to 8 times.

As a method for dyeing a polyvinyl alcohol resin film with a dichroic dye, for example, a method of immersing the film in an aqueous solution containing a dichroic dye is employed. Iodine and dichroic organic dyes are used as the dichroic dye. In addition, it is preferable that the polyvinyl alcohol resin film is subjected to a immersion treatment in water before the dyeing treatment.

As the dyeing treatment with iodine, a method is usually employed in which a polyvinyl alcohol resin film is immersed in an aqueous solution containing iodine and potassium iodide. The content of iodine in this aqueous solution can be about 0.01 to 1 part by mass per 100 parts by mass of water.
The content of potassium iodide can be about 0.5 to 20 parts by mass per 100 parts by mass of water. Further, the temperature of this aqueous solution can be about 20 to 40°C. On the other hand, as a dyeing treatment using a dichroic organic dye, a method is usually employed in which a polyvinyl alcohol resin film is immersed in an aqueous solution containing a dichroic organic dye. The aqueous solution containing the dichroic organic dye may contain an inorganic salt such as sodium sulfate as a dyeing aid. The content of the dichroic organic dye in this aqueous solution can be about 1×10 ⁻⁴ to 10 parts by mass per 100 parts by mass of water. The temperature of this aqueous solution can be about 20 to 80°C.

As the boric acid treatment after dyeing with a dichroic dye, a method is usually adopted in which the dyed polyvinyl alcohol resin film is immersed in an aqueous solution containing boric acid. When using iodine as the dichroic dye, the boric acid-containing aqueous solution preferably contains potassium iodide.
The amount of boric acid in the boric acid-containing aqueous solution can be about 2 to 15 parts by weight per 100 parts by weight of water. The amount of potassium iodide in this aqueous solution can be about 0.1 to 20 parts by weight per 100 parts by weight of water. The temperature of this aqueous solution can be 50°C or higher, for example 50-85°C.

The polyvinyl alcohol resin film treated with boric acid is usually washed with water. The water washing treatment can be performed, for example, by immersing the boric acid-treated polyvinyl alcohol resin film in water. The temperature of water in the washing process is usually about 5 to 40°C.
After washing with water, a drying process is performed to obtain a polarizer. The drying process can be performed using a hot air dryer or a far-infrared heater. A polarizing plate can be obtained by laminating protective films on both sides of this polarizer using an adhesive.

Further, other examples of the method for manufacturing a polarizer include methods described in JP-A No. 2000-338329 and JP-A No. 2012-159778. In this method, a solution containing a polyvinyl alcohol resin is applied to the surface of a base film to form a resin layer, and then a laminated film consisting of the base film and the resin layer is stretched, and then dyed, crosslinked, etc. to form a polarizer layer from the resin layer. This polarizing laminated film consists of a base film and a polarizer layer. After laminating a protective film on the polarizer layer surface, the base film is peeled and removed, and furthermore, the polarizer layer surface exposed by peeling the base film is coated with a protective film. A polarizing plate can be obtained by laminating one of the protective films.

The thickness of the polarizer can be 40 μm or less, preferably 30 μm or less (for example, 20 μm or less). In addition, according to the method described in JP-A No. 2000-338329 and JP-A No. 2012-159778, a thin film polarizer can be manufactured more easily, and the thickness of the polarizer can be, for example, 20 μm or less, and can also be set to 10 μm or less. The thickness of the polarizer is usually 2 μm or more. Reducing the thickness of the polarizer is advantageous in reducing the thickness of the polarizing plate and, by extension, the image display device.

[3] Protective film The protective film is made of a translucent (preferably optically transparent) thermoplastic resin, such as a chain polyolefin resin (polypropylene resin, etc.), a cyclic polyolefin resin (norbornene resin, etc.). ); Cellulose resins such as cellulose ester resins such as triacetyl cellulose and diacetyl cellulose; Polyester resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; Polycarbonate resins; (meth)acrylic resins It can be a resin film made of a resin; or a mixture or copolymer thereof. Note that "(meth)acrylic" means methacrylic and/or acrylic, and "(meth)" when referring to "(meth)acrylate" has the same meaning. Of these, the first protective film 10 and the second protective film 20 (or the main component of the protective film) are made of cellulose resin, (meth)acrylic resin, polyolefin resin, polyester resin, and polycarbonate resin, respectively. It is preferable that at least one resin selected from the group consisting of:

The protective film may be an unstretched film or a uniaxially or biaxially stretched film. The biaxial stretching may be simultaneous biaxial stretching in which the film is stretched in two stretching directions simultaneously, or sequential biaxial stretching in which the film is stretched in a predetermined direction and then in another direction. The protective film can also be a protective film that also has an optical function, such as a retardation film. A retardation film is an optically functional film used for the purpose of compensating for retardation caused by a liquid crystal cell, which is an image display element. For example, a retardation film that is given an arbitrary retardation value by stretching (uniaxial stretching or biaxial stretching, etc.) a film made of the above-mentioned thermoplastic resin, or by forming a liquid crystal layer or the like on the film. It can be done.

Examples of the chain polyolefin resin include homopolymers of chain olefins such as polyethylene resins and polypropylene resins, as well as copolymers of two or more types of chain olefins.

Cyclic polyolefin resin is a general term for resins containing a cyclic olefin as a polymer unit, representative examples of which are norbornene, tetracyclododecene (also known as dimetanooctahydronaphthalene), or derivatives thereof. Specific examples of cyclic polyolefin resins include ring-opened (co)polymers of cyclic olefins and their hydrogenated products, addition polymers of cyclic olefins, cyclic olefins and chain olefins such as ethylene and propylene, or those having vinyl groups. These include copolymers with aromatic compounds, and modified (co)polymers obtained by modifying these with unsaturated carboxylic acids or derivatives thereof. Among these, norbornene resins using norbornene monomers such as norbornene and polycyclic norbornene monomers as the cyclic olefin are preferably used.

The cellulose resin is preferably a cellulose ester resin in which at least a part of the hydroxyl groups in cellulose is acetate-esterified, and a mixed ester resin in which a part is acetate-esterified and a part is esterified with another acid. You can. The cellulose ester resin is preferably an acetyl cellulose resin. Specific examples of cellulose acetate resins include cellulose triacetate, cellulose diacetate, cellulose acetate propionate, cellulose acetate butyrate, and the like.

The polyester resin is a resin other than the above-mentioned cellulose ester resin that has an ester bond, and is generally a polycondensate of a polycarboxylic acid or a derivative thereof and a polyhydric alcohol. Specific examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexane dimethyl terephthalate, polycyclohexane dimethyl naphthalate, etc. It will be done. Among these, polyethylene terephthalate is preferably used from the viewpoint of mechanical properties, solvent resistance, scratch resistance, cost, etc. Polyethylene terephthalate means a resin in which 80 mol% or more of repeating units are composed of ethylene terephthalate, and may contain structural units derived from other copolymer components.

Other copolymerization components include dicarboxylic acid components and diol components. Dicarboxylic acid components include isophthalic acid, 4,4'-dicarboxydiphenyl, 4,4'-dicarboxybenzophenone, bis(4-carboxyphenyl)ethane, adipic acid, sebacic acid, 5-sodium sulfoisophthalic acid, 1 , 4-dicarboxycyclohexane and the like. Examples of the diol component include propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, ethylene oxide adduct of bisphenol A, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like. The dicarboxylic acid component and the diol component can also be used in combination of two or more types, if necessary. It is also possible to use hydroxycarboxylic acids such as p-hydroxybenzoic acid and p-β-hydroxyethoxybenzoic acid together with the dicarboxylic acid component and diol component. As other copolymerization components, a small amount of dicarboxylic acid components and/or diol components having amide bonds, urethane bonds, ether bonds, carbonate bonds, etc. may be used.

Polycarbonate resin is a polyester formed from carbonic acid and glycol or bisphenol. Among these, aromatic polycarbonates having diphenylalkane in the molecular chain are preferably used from the viewpoints of heat resistance, weather resistance, and acid resistance. Examples of polycarbonates include 2,2-bis(4-hydroxyphenyl)propane (also known as bisphenol A), 2,2-bis(4-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1, Examples include polycarbonates derived from bisphenols such as 1-bis(4-hydroxyphenyl)isobutane and 1,1-bis(4-hydroxyphenyl)ethane.

The (meth)acrylic resin can be a polymer containing methacrylic acid ester as the main monomer (containing 50% by mass or more), and a copolymer in which a small amount of other copolymer components are copolymerized. Preferably, it is a polymer. The (meth)acrylic resin is more preferably a copolymer of methyl methacrylate and methyl acrylate, and a third monofunctional monomer may be further copolymerized.

Examples of the third monofunctional monomer include methyl methacrylates such as ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, and 2-hydroxyethyl methacrylate. Acrylic esters such as ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate; 2-(hydroxy Hydroxyalkyl acrylic esters such as methyl) acrylate, 2-(1-hydroxyethyl) methyl acrylate, 2-(hydroxymethyl) ethyl acrylate, and 2-(hydroxymethyl) butyl acrylate; methacrylic acid, acrylic Unsaturated acids such as acids; halogenated styrenes such as chlorostyrene and bromostyrene; substituted styrenes such as vinyltoluene and α-methylstyrene; unsaturated nitriles such as acrylonitrile and methacrylonitrile; maleic anhydride, anhydride Examples include unsaturated acid anhydrides such as citraconic acid; unsaturated imides such as phenylmaleimide and cyclohexylmaleimide. The third monofunctional monomer may be used alone or in combination of two or more.

The (meth)acrylic resin may further be copolymerized with a polyfunctional monomer. Examples of the polyfunctional monomer include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, and nonaethylene glycol di(meth)acrylate. Acrylate, tetradecaethylene glycol di(meth)acrylate, and other ethylene glycols or their oligomers, with both terminal hydroxyl groups esterified with (meth)acrylic acid; Propylene glycol or its oligomers, with both terminal hydroxyl groups esterified with (meth)acrylic acid. Esterified products; esterification of the hydroxyl group of dihydric alcohols such as neopentyl glycol di(meth)acrylate, hexanediol di(meth)acrylate, butanediol di(meth)acrylate with (meth)acrylic acid; Bisphenol A , alkylene oxide adducts of bisphenol A, or halogen-substituted products of these, with both terminal hydroxyl groups esterified with (meth)acrylic acid; polyhydric alcohols such as trimethylolpropane and pentaerythritol esterified with (meth)acrylic acid. dibasic acids such as succinic acid, adipic acid, terephthalic acid, phthalic acid, and halogen-substituted products of these; Examples include ring-opening addition of an epoxy group of glycidyl (meth)acrylate to an alkylene oxide adduct; aryl (meth)acrylate; aromatic divinyl compounds such as divinylbenzene; Among these, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and neopentyl glycol dimethacrylate are preferably used.

The (meth)acrylic resin may be modified by further performing a reaction between the functional groups of the copolymer. Examples of such reactions include, for example, the intra-polymer chain demethanol condensation reaction between the methyl ester group of methyl acrylate and the hydroxyl group of 2-(hydroxymethyl)methyl acrylate, and the reaction between the carboxyl group of acrylic acid and the 2-(hydroxymethyl) acrylate Examples include intra-polymer chain dehydration condensation reaction with the hydroxyl group of acid methyl.

The glass transition temperature of the (meth)acrylic resin is preferably 80 to 160°C. The glass transition temperature is determined by the polymerization ratio of the methacrylic ester monomer and acrylic ester monomer, the carbon chain length of each ester group, the type of functional group containing them, and the polyfunctionality of the entire monomer. It can be controlled by adjusting the polymerization ratio of monomers.

Furthermore, as a means for increasing the glass transition temperature of (meth)acrylic resin, it is also effective to introduce a ring structure into the main chain of the polymer. The ring structure is preferably a heterocyclic structure such as a cyclic acid anhydride structure, a cyclic imide structure, and a lactone structure. Specific examples include cyclic acid anhydride structures such as glutaric anhydride structures and succinic anhydride structures, cyclic imide structures such as glutarimide structures and succinimide structures, and lactone ring structures such as butyrolactone and valerolactone. The glass transition temperature of the (meth)acrylic resin can be increased as the content of the ring structure in the main chain is increased. The cyclic acid anhydride structure and the cyclic imide structure can be introduced by copolymerizing a monomer having a cyclic structure such as maleic anhydride and maleimide, or by dehydration/methanol condensation reaction after polymerization. It can be introduced by a method of introducing a cyclic imide structure, a method of reacting an amino compound to introduce a cyclic imide structure, and the like. A resin (polymer) having a lactone ring structure is obtained by preparing a polymer having a hydroxyl group and an ester group in the polymer chain, and then converting the hydroxyl group and ester group in the obtained polymer to the necessary amount by heating. Depending on the case, it can be obtained by a method in which a lactone ring structure is formed by cyclization condensation in the presence of a catalyst such as an organic phosphorus compound.

The (meth)acrylic resin may contain additives as necessary. Examples of additives include lubricants, antiblocking agents, heat stabilizers, antioxidants, antistatic agents, light resistance agents, impact resistance modifiers, and surfactants.

The (meth)acrylic resin may contain acrylic rubber particles as an impact modifier from the viewpoint of film formability and impact resistance of the film. Acrylic rubber particles are particles whose essential component is an elastic polymer mainly composed of acrylic acid ester. Examples include those with a multilayer structure. An example of this elastic polymer is a crosslinked elastic copolymer containing alkyl acrylate as a main component and copolymerizing this with other copolymerizable vinyl monomers and crosslinkable monomers. Examples of the alkyl acrylate that is the main component of the elastic polymer include methyl acrylate (methyl acrylate), ethyl acrylate, butyl acrylate (butyl acrylate), and 2-ethylhexyl acrylate, depending on the number of carbon atoms in the alkyl group. is about 1 to 8, and alkyl acrylates having an alkyl group having 4 or more carbon atoms are preferably used. Other vinyl monomers that can be copolymerized with this alkyl acrylate include compounds having one polymerizable carbon-carbon double bond in the molecule, and more specifically, methyl methacrylate. Examples include methacrylic acid esters such as, aromatic vinyl compounds such as styrene, vinyl cyan compounds such as acrylonitrile, and the like. Examples of the crosslinkable monomer include crosslinkable compounds having at least two polymerizable carbon-carbon double bonds in the molecule, and more specifically, ethylene glycol di(meth)acrylate, butanediol, etc. Examples include (meth)acrylates of polyhydric alcohols such as di(meth)acrylate, alkenyl esters of (meth)acrylic acid such as allyl(meth)acrylate, and divinylbenzene.

The protective film can also be a laminate of a film made of a (meth)acrylic resin that does not contain rubber particles and a film made of a (meth)acrylic resin that contains rubber particles. Moreover, a (meth)acrylic resin layer can be formed on one or both sides of a retardation developing layer made of a resin different from the (meth)acrylic resin, and a retardation can be developed to form a protective film.

The protective film may contain an ultraviolet absorber. When applying a polarizing plate to an image display device such as a liquid crystal display device, a protective film containing an ultraviolet absorber is placed on the viewing side of the image display element (for example, a liquid crystal cell) to prevent deterioration of the image display element due to ultraviolet rays. can be suppressed. Examples of the ultraviolet absorber include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, and nickel complex compounds.

In FIG. 1, the first protective film 10 and the second protective film 20 may be made of the same resin, or may be made of different resins. Further, the first protective film 10 and the second protective film 20 may be the same or different in thickness, the presence or absence of additives, the type thereof, retardation characteristics, and the like.

The first protective film 10 and/or the second protective film 20 have a hard coat layer, an anti-glare layer, an anti-reflection layer, a light-diffusing layer, an anti-static layer, an anti-static layer, etc. on the outer surface (the surface opposite to the polarizer 30). It may have a surface treatment layer (coating layer) such as a dirt layer or a conductive layer.

The thickness of the first protective film 10 and the second protective film 20 is usually 5 to 200 μm, preferably 10 to 120 μm, and more preferably 10 to 85 μm. Reducing the thickness of the protective film is advantageous in reducing the thickness of the polarizing plate and, by extension, the image display device.

<Manufacturing method of polarizing plate>
The polarizing plate according to the present invention is
(a) a step of applying an adhesive to the polarizer and/or the protective film; (b) a step of laminating the polarizer and the protective film; (c) a step of irradiating the laminate obtained in step (b) with active energy rays; and (d) then heating the laminate.

For example, in the polarizing plate shown in FIG. It can be formed by laminating and adhering the second protective film 20 via the layer 25. The first protective film 10 and the second protective film 20 (hereinafter, these may be collectively referred to simply as "protective films") may be laminated and bonded on one side in stages, or the protective films on both sides may be bonded together. Lamination and bonding may be performed in one step.

Specifically, an adhesive is applied to the bonding surface of the polarizer 30 and/or the bonding surface of the protective film (step (a)), and both films are overlapped with the adhesive coating layer interposed therebetween. They are laminated and laminated by pressing from above and below using a mating roll or the like (step (b)). Next, after irradiating with active energy rays (step (c), referred to as "active energy ray irradiation step"), the adhesive layer is cured by further heating (step (d), referred to as "heating step"). Form a polarizing plate. Note that before forming the adhesive coating layer, one or both of the bonding surfaces of the polarizer 30 and the protective film are subjected to saponification treatment, corona discharge treatment, plasma treatment, flame treatment, primer treatment, and anchor coating. A treatment for facilitating adhesion such as a treatment may be applied.

In the method for manufacturing a polarizing plate of the present invention, in the active energy irradiation step (c), the second acid generator mainly acts to harden the cationically polymerizable compound. Furthermore, in the heating step (d), the first acid generator mainly acts to further harden the uncured or insufficiently cured cationic polymerizable compound in the active energy irradiation step. As mentioned above, in the present invention, since the adhesive is composed of a combination of a predetermined cationic polymerizable compound and a predetermined second acid generator, the active energy irradiation process creates an adhesive with relatively high adhesion. In addition, in the heating step, the first acid generator having a counter anion with a relatively high acidity of the conjugate acid acts and accelerates curing, resulting in improved peel resistance, curl resistance, and A polarizing plate with excellent deterioration resistance (moisture heat resistance) can be formed.

In steps (a) and (b), various coating methods such as a doctor blade, wire bar, die coater, comma coater, and gravure coater can be used to form the adhesive coating layer. Alternatively, it is also possible to adopt a method in which the adhesive is cast while continuously supplying the polarizer 30 and the protective film so that their bonded surfaces are on the inside.

From the viewpoint of coatability, the adhesive forming the first adhesive layer 15 and the second adhesive layer 25 preferably has a low viscosity. Specifically, the viscosity at 25° C. is preferably 1000 mPa·s or less, more preferably 500 mPa·s or less, and still more preferably 100 mPa·s or less. The adhesive may be solvent-free, but may contain an organic solvent to adjust the viscosity to suit the coating method employed.

In step (c), the active energy ray light source may be any source that generates ultraviolet rays, electron beams, X-rays, etc., and preferably ultraviolet rays. As the ultraviolet light source, a light source having an emission distribution at a wavelength of 400 nm or less is preferable, such as a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a chemical lamp, a black light lamp, a microwave-excited mercury lamp, a metal halide lamp, etc. be able to.

The active energy ray irradiation intensity to the adhesive layer is determined for each adhesive, but the light irradiation intensity in the wavelength range effective for activating the second acid generator is 0.1 to 1000 mW/cm ² It is preferable to do so. If the light irradiation intensity is too low, the reaction time will be too long; on the other hand, if the light irradiation intensity is too high, the heat radiated from the lamp and the heat generated during polymerization of the adhesive may cause yellowing of the adhesive layer or polarization. This may cause deterioration of the child 30 or poor skin of the protective film. Further, the light irradiation time to the adhesive is also controlled for each adhesive, but the cumulative light amount expressed as the product of the light irradiation intensity and the light irradiation time is, for example, 10 to 3000 mJ/cm ² , preferably 10 to 3000 mJ/cm 2 . It is set to 1000 mJ/cm ² , more preferably 50 to 500 mJ/cm ² , and still more preferably 100 to 300 mJ/cm ² . If the cumulative light amount is below the upper limit, the light irradiation time will not be too long, which is advantageous for improving productivity, and if it is above the lower limit, the acid generator (especially the second acid generator) will effectively generate the acid. can be generated and the adhesive layer can be sufficiently cured.

The active energy ray may be irradiated from either side of the protective film or the polarizing film, but it is usually irradiated from the side of the film that has a high transmittance near the absorption wavelength of the second acid generator.
Since the present invention uses the first acid generator in combination, the transmittance at 320 nm is 85% or less (preferably 70% or less), and the transmittance at 300 nm is 50% or less (preferably 10% or less). ) Even when active energy rays are irradiated through a protective film with low transmittance, such as a protective film with low transmittance, the first acid generator acts upon heating, sufficiently curing the adhesive and improving the durability of the polarizing plate. . Further, the present invention has a transmittance of 85% or less (preferably 70% or less) at 320 nm, a transmittance of 50% or less (preferably 10% or less) at 300 nm, and a transmittance of 85% at 350 nm. Durability is improved even when active energy rays are irradiated through a protective film with low transmittance as shown below.

In step (d), at least the adhesive layer may be heated; for example, the laminate of the protective films 10 and 20, the adhesive layers 15 and 25, and the polarizer 30 may be heated. Examples of heating methods include passing a long protective film or laminate one by one through a device that emits radiant heat such as an infrared heater, or heating a long protective film or laminate with gas using a blower or the like. Examples include a method of spraying. The heating temperature can be appropriately selected depending on the curing temperature of the first acid generator. Specifically, the temperature at which the first acid generator easily generates acid is preferable, for example, the curing temperature ±30°C, preferably the curing temperature ±20°C, and more preferably the curing temperature ±10°C. can. When it is within this range, the cationic polymerizable compound that is uncured or insufficiently cured can be effectively cured in the active energy irradiation step, so that the adhesion between the polarizer and the protective film can be improved. A specific heating temperature can be, for example, 50 to 150°C, preferably 70 to 120°C, more preferably 80 to 100°C, particularly 85 to 95°C. Within this range, thermal deterioration of the polarizing plate can be suppressed, and it is also advantageous from the viewpoint of polymerizability and curability of the cationically polymerizable compound.
Further, in the present invention, since a predetermined first acid generator is used, the curing speed is relatively high. Therefore, the heating time of the heating step is, for example, 1 second to 1 hour, preferably 10 seconds to 30 minutes (for example, 20 seconds to 10 minutes), more preferably 30 seconds to 5 minutes, particularly 50 seconds to 2 minutes. can do.

The timing of laminating the protective film on the polarizer 30 via the coating layer of the adhesive 15 or 25 and the timing of curing the coating layer are not particularly limited. For example, after laminating one protective film 10, the coating layer can be cured, and then the other protective film 20 can be laminated and the coating layer can be cured. Alternatively, after laminating both protective films sequentially or simultaneously, the coating layers on both sides may be cured simultaneously. Moreover, in step (c), irradiation with active energy rays may be performed from either side of the protective film.

The thickness of the adhesive layer after curing (for example, the thickness of the first and second adhesive layers 15, 25) is usually 20 μm or less, preferably 10 μm or less, more preferably 5 μm or less, particularly preferably 3 μm or less. The thickness of the adhesive layer is usually 0.01 μm or more, preferably 0.1 μm or more. Note that the first adhesive layer 15 and the second adhesive layer 25 may have the same or different thicknesses.

<Other components of the polarizing plate>
(1) Optical Functional Film The polarizing plate can include an optically functional film other than the polarizer 30 to impart a desired optical function, and a suitable example thereof is a retardation film. For example, in the polarizing plate shown in FIG. 1, the first protective film 10 and/or the second protective film 20 can also serve as a retardation film, but a retardation film can also be laminated separately from the protective film. . In the latter case, the retardation film can be laminated on the outer surface of the first protective film 10 and/or the second protective film 20 via a pressure-sensitive adhesive layer or an adhesive layer.

Specific examples of retardation films include birefringent films made of stretched films of translucent thermoplastic resins, films with fixed orientation of discotic liquid crystals or nematic liquid crystals, and films with the above liquid crystal layer on a base film. including those formed. The base film is usually a thermoplastic resin film, and as the thermoplastic resin, cellulose ester resins such as triacetylcellulose are preferably used.

As the thermoplastic resin forming the birefringent film, those described for the protective film can be used. For example, when using a cellulose ester resin, there is a method of forming a film from a cellulose ester resin containing a compound having a retardation adjustment function, and a method of forming a film from a cellulose ester resin containing a compound having a retardation adjustment function. A birefringent film can be obtained by applying a compound having an adjusting function or by stretching a cellulose ester resin uniaxially or biaxially. As the thermoplastic resin forming the birefringent film, other thermoplastic resins such as polyvinyl alcohol resin, polystyrene resin, polyarylate resin, and polyamide resin can also be used.

Two or more retardation films may be used in combination for the purpose of controlling optical properties such as widening the band. Moreover, not only a film having optical anisotropy but also a substantially optically isotropic zero retardation film can be used as the retardation film. The zero retardation film refers to a film whose in-plane retardation value R _e and thickness direction retardation value R _th are both −15 to 15 nm. The in-plane retardation value R _e and the thickness direction retardation value R _th here are values at a wavelength of 590 nm.

The in-plane retardation value R _e and the thickness direction retardation value R _th are each calculated by the following formula:
R _e = (n _x - n _y ) x d
R _th = [(n _x + n _y )/2-n _z ]×d
Defined by In the formula, n _x is the refractive index in the slow axis direction (x-axis direction) in the film plane, and n _y is the refractive index in the fast axis direction (in-plane y-axis direction perpendicular to the x-axis) in the film plane. is the refractive index, n _z is the refractive index in the film thickness direction (z-axis direction perpendicular to the film surface), and d is the thickness of the film.

For the zero retardation film, thermoplastic resins described for protective films and birefringent films can be used, such as polyolefin resins such as cellulose ester resins, chain polyolefin resins, and cyclic polyolefin resins, A resin film made of polyester resin such as polyethylene terephthalate can be used. Among these, cellulose ester resins and polyolefin resins are preferably used because the retardation value can be easily controlled and they are easily available.

Examples of other optically functional films (optical members) that can be included in the polarizing plate include light condensing plates, brightness enhancement films, reflective layers (reflective films), semi-transparent reflective layers (semi-transparent reflective films), and light diffusing layers (light diffusion film) etc. These are generally provided when the polarizing plate is a polarizing plate placed on the back side (backlight side) of the liquid crystal cell.

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

A brightness enhancement film is used for the purpose of improving brightness in a liquid crystal display device to which a polarizing plate is applied. Specifically, we are developing reflective polarization separation sheets designed to create anisotropy in reflectance by laminating multiple thin films with different anisotropy of refractive index, and oriented films of cholesteric liquid crystal polymers and their orientation. Examples include circularly polarized light separating sheets in which a liquid crystal layer is supported on a base film.

The reflective layer, the semi-transmissive reflective layer, and the light diffusing layer are provided to make the polarizing plate a reflective, semi-transmissive, and diffusive optical member, respectively. A reflective polarizing plate is used in a type of liquid crystal display device that displays by reflecting incident light from the viewing side, and since a light source such as a backlight can be omitted, it is easy to make the liquid crystal display device thinner. A semi-transmissive polarizing plate is used in a type of liquid crystal display device that uses light from a backlight to display information in a dark place and as a reflective type in a bright place. Further, a diffusion type polarizing plate is used in a liquid crystal display device that provides light diffusivity and suppresses display defects such as moire. The reflective layer, the semi-transparent reflective layer, and the light diffusing layer can be formed by a known method.

(2) Adhesive layer The polarizing plate according to the present invention can include an adhesive layer for bonding it to an image display element such as a liquid crystal cell or other optical member. The adhesive layer can be laminated on the outer surface of the protective film.

As the adhesive used in the adhesive layer, those having base polymers such as (meth)acrylic resins, silicone resins, polyester resins, polyurethane resins, and polyether resins can be used. Among these, (meth)acrylic pressure-sensitive adhesives are preferably used from the viewpoints of transparency, adhesive strength, reliability, weather resistance, heat resistance, reworkability, and the like. (Meth)acrylic adhesives include (meth)acrylic acid alkyl esters having alkyl groups with carbon numbers of 20 or less, such as methyl, ethyl, and butyl groups, and (meth)acrylic acid and (meth)acrylic acid. A (meth)acrylic monomer containing a functional group such as hydroxyethyl is blended so that the glass transition temperature is preferably 25°C or less, more preferably 0°C or less, and has a weight average molecular weight of 100,000 or more. Acrylic resins are useful as base polymers.

To form an adhesive layer on a polarizing plate, for example, the adhesive composition is dissolved or dispersed in an organic solvent such as toluene or ethyl acetate to prepare a 10 to 40% by mass solution, and this is applied to the target surface of the polarizing plate. A method in which the adhesive layer is formed by directly coating the film, or a method in which the adhesive layer is formed in the form of a sheet on a release-treated separate film and then transferred to the target surface of the polarizing plate. It can be done by etc. The thickness of the adhesive layer is determined depending on its adhesive strength, etc., but is suitably in the range of about 1 to 50 μm, preferably 2 to 40 μm.

The polarizing plate may include the above-described separate film. The separate film can be a film made of a polyethylene resin such as polyethylene, a polypropylene resin such as polypropylene, a polyester resin such as polyethylene terephthalate, or the like. Among these, a stretched film of polyethylene terephthalate is preferred.

The adhesive layer contains fillers such as glass fibers, glass beads, resin beads, metal powders and other inorganic powders, pigments, colorants, antioxidants, ultraviolet absorbers, antistatic agents, etc. as necessary. may have been done.

Examples of the antistatic agent include ionic compounds, conductive fine particles, conductive polymers, etc., and ionic compounds are preferably used. The cation component constituting the ionic compound may be an inorganic anion or an organic anion, but is preferably an organic cation from the viewpoint of compatibility with the (meth)acrylic resin. Examples of organic cations include pyridinium cations, imidazolium cations, ammonium cations, sulfonium cations, and phosphonium cations. On the other hand, the anion component constituting the ionic compound may be an inorganic anion or an organic anion, but an anion component containing a fluorine atom is preferred since it provides an ionic compound with excellent antistatic performance. Examples of anion components containing a fluorine atom include hexafluorophosphate anion [(PF ₆ ⁻ )], bis(trifluoromethanesulfonyl)imide anion [(CF ₃ SO ₂ ) ₂ N ⁻ ] anion, and bis(fluorosulfonyl)imide anion [ (FSO ₂ ) ₂ N ⁻ ] anion and the like.

(3) Protect film The polarizing plate according to the present invention can include a protect film for temporarily protecting its surface (protective film surface). For example, after a polarizing plate is bonded to an image display element or other optical member, the protect film is peeled off together with the adhesive layer it has.

The protect film is composed of a base film and an adhesive layer laminated thereon.
Regarding the adhesive layer, the above description is cited. The resin constituting the base film is, for example, a thermoplastic resin such as a polyethylene resin such as polyethylene, a polypropylene resin such as polypropylene, a polyester resin such as polyethylene terephthalate or polyethylene naphthalate, or a polycarbonate resin. be able to. Preferably, it is a polyester resin such as polyethylene terephthalate.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. In the following examples, the following were used as the cationically polymerizable compound, the first acid generator, and the second acid generator constituting the adhesive.

(Cationic polymerizable compound)
<Manufacture example 1>
The following compounds (A-1), compound (A-2) and compound (A-3) were used as cationic polymerizable compounds (A-1):(A-2):(A-3)=70:25 :5 mass ratio. The obtained cationically polymerizable compound was designated as "cationically polymerizable compound A."
Compound (A-1): 3',4'-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate (manufactured by Daicel Corporation, trade name "CEL2021P", epoxy equivalent: 126 to 145 g/equivalent)
Compound (A-2): Neopentyl glycol diglycidyl ether (manufactured by Nagase ChemteX Co., Ltd., trade name "EX-211L", epoxy equivalent: 108 to 130 g/equivalent),
Compound (A-3): 3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane (manufactured by Toagosei Co., Ltd., trade name "OXT-221")
<Manufacture example 2>
A cationic polymerizable compound was prepared by mixing the following compound (A-1) and compound (A-2) at a mass ratio of (A-1):(A-2)=40:60. The obtained cationic polymerizable compound was designated as "cationic polymerizable compound B."
Compound (A-1): 3',4'-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate (manufactured by Daicel Corporation, trade name "CEL2021P", epoxy equivalent: 126 to 145 g/equivalent)
Compound (A-2): Neopentyl glycol diglycidyl ether (manufactured by Nagase ChemteX Co., Ltd., trade name "EX-211L", epoxy equivalent: 108 to 130 g/equivalent)

化合物（Ｂ－３）：下記の構造の酸発生剤を用いた。硬化温度；１１３℃。

(First acid generator)
Compound (B-1): An acid generator having the following structure was used. Curing temperature: 100°C.

Compound (B-3): An acid generator having the following structure was used. Curing temperature: 113°C.

化合物（Ｂ－４）：下記の構造の酸発生剤を用いた。硬化温度：２１９℃。

(Second acid generator)
Compound (B-2): An acid generator having the following structure (manufactured by San-Apro Co., Ltd., trade name "CPI-100P") was used. Curing temperature: 272°C.

Compound (B-4): An acid generator having the following structure was used. Curing temperature: 219°C.

(Measurement of curing temperature of acid generator)
The curing temperature of the acid generator was measured by the following method.
A curable resin composition is prepared by adding 1 part by mass (solid content) of the first acid generator (B-1) or the second acid generator (B-2) to 100 parts by mass of the compound (A-1). Then, 10 mg of this was collected, placed in an aluminum press-lid type container, and sealed by pressing to prepare a sample for measurement. Next, the container containing the measurement sample was placed in a differential scanning calorimeter (DSC) [EXSTAR-6000 DSC6220, manufactured by SII Nanotechnology Co., Ltd.], and heated to 10°C while purging with nitrogen gas. The temperature was raised from 30°C to 300°C at a rate of 1/min. From the obtained DSC curve, the temperature at which the amount of heat generated reached the maximum value was defined as the curing temperature. In addition, in the DSC curve obtained by collecting 10 mg of "CEL2021P" alone and operating in the same manner as above, neither endotherm nor exotherm was observed between 30°C and 200°C. Further, B-2 is a 50% solution, and the solid content is 1 part by mass per 100 parts by mass of compound (A-1).

The curing temperatures of the first acid generator (B-3) and the second acid generator (B-4) were also measured in the same manner as above. Note that the second acid generator (B-4) is blended as a 50% propylene carbonate solution, and the solid content is 1 part by mass per 100 parts by mass of compound (A-1).

(1) Preparation of adhesive The above cationic polymerizable compound, first acid generator, and second acid generator were mixed in 20 mL at the blending ratios listed in Table 1 (the numbers in Table 1 indicate parts by mass). The liquid UV-curable adhesives were prepared by weighing them into a screw tube, mixing and defoaming them. The second acid generator (B-2) and the second acid generator (B-4) were blended as a 50% propylene carbonate solution, and Table 1 shows the solid content thereof.

(2) Preparation of polarizing plate <Examples 1 and 2>
Acetyl cellulose resin film with a thickness of 80 μm containing a UV absorber (manufactured by Konica Minolta Opto Co., Ltd., product name "Konicatack KC8UX2MW", transmittance of 0% at a wavelength of 300 nm, transmittance of 0% at a wavelength of 320 nm, transmittance at a wavelength of 350 nm) Corona discharge treatment was applied to one side of the (transmittance 0%), and the adhesive listed in Table 1 was coated on the corona discharge treated surface using a bar coater so that the thickness after curing was approximately 2.5 μm. . Next, a 25 μm thick polyvinyl alcohol (PVA)-iodine polarizing film (polarizer) was attached to the coated surface. Next, a retardation film with a thickness of 50 μm made of a cyclic polyolefin resin (norbornene resin) (manufactured by Zeon Co., Ltd., trade name “ZEONOR”, transmittance of 90% at a wavelength of 300 nm, transmittance of 90% at a wavelength of 320 nm, Corona discharge treatment was applied to one side of the substrate (transmittance of 91% at a wavelength of 350 nm), and the adhesive listed in Table 1 was applied to the corona discharge treated surface using a bar coater so that the thickness after curing was approximately 2.5 μm. It was coated with On the coated surface, the polarizing film with the acetyl cellulose resin film produced above was stacked on the polarizing film side, and pressed and bonded using a bonding roll to obtain a laminate. This laminate was irradiated with ultraviolet rays from the cyclic polyolefin resin film side using an ultraviolet irradiation device with a belt conveyor [the lamp used was "D Bulb" manufactured by Fusion UV Systems] to give an integrated light amount of 200 mJ/cm ² ( UVB) was irradiated with ultraviolet rays, and then heated at a temperature of 90° C. for 1 minute to harden the adhesive layers on both sides, thereby producing a polarizing plate.

<Comparative example 1>
A polarizing plate was produced in the same manner as in Example 1, except that the laminate after bonding was heated at a temperature of 90° C. for 5 minutes without irradiating ultraviolet rays. Although the adhesive was heated at a temperature of 90° C. for 1 minute, the adhesive did not harden, so it was heated for 5 minutes.

<Examples 3 to 6 (Example 5 is a reference example) >
Polarizing plates were produced in the same manner as in Example 1, except that the adhesives were changed to those listed in Table 1.

<Example 7>
A polarizing plate was produced in the same manner as in Example 1, except that the adhesive was changed to the adhesive listed in Table 1, and the polarizing plate was heated at 100° C. for 1 minute after irradiation with ultraviolet rays.

<Example 8>
A polarizing plate was produced in the same manner as in Example 1, except that the adhesive was changed to the adhesive listed in Table 1.

<Example 9>
A polarizing plate was produced in the same manner as in Example 1, except that the adhesive was changed to the adhesive listed in Table 1, and the polarizing plate was heated at 100° C. for 1 minute after irradiation with ultraviolet rays.

<Example 10>
A polarizing plate was produced in the same manner as in Example 1, except that the adhesive was changed to the adhesive listed in Table 1.

<Example 11>
Corona discharge treatment was applied to one side of an 80 μm thick acetyl cellulose resin film containing an ultraviolet absorber (manufactured by Konica Minolta Opto Co., Ltd., trade name "KONICA TACK KC8UX2MW"), and the corona discharge treated surface was treated with the following chemicals as shown in Table 1. The adhesive described above was coated using a bar coater so that the thickness after curing was approximately 2.5 μm. Next, a 25 μm thick polyvinyl alcohol (PVA)-iodine polarizing film (polarizer) was attached to the coated surface. Next, a corona discharge treatment was applied to one side of a 25 μm thick film made of polyester resin (polyethylene terephthalate) (0% transmittance at a wavelength of 300 nm, 68% transmittance at a wavelength of 320 nm, and 83% at a wavelength of 350 nm). The adhesive listed in Table 1 was coated on the corona discharge treated surface using a bar coater so that the thickness after curing was approximately 2.5 μm. On the coated surface, the polarizing film with the acetyl cellulose resin film produced above was stacked on the polarizing film side, and pressed and bonded using a bonding roll to obtain a laminate. This laminate was irradiated from the polyester resin film side with an ultraviolet ray irradiation device equipped with a belt conveyor [the lamp used was "D Bulb" manufactured by Fusion UV Systems] to give an integrated light amount of 400 mJ/cm ² (UVB ), and then heated at 90° C. for 1 minute to harden the adhesive layers on both sides to produce a polarizing plate.

<Example 12>
Corona discharge treatment was applied to one side of an 80 μm thick acetyl cellulose resin film containing an ultraviolet absorber (manufactured by Konica Minolta Opto Co., Ltd., trade name "KONICA TACK KC8UX2MW"), and the corona discharge treated surface was treated with the following chemicals as shown in Table 1. The adhesive described above was coated using a bar coater so that the thickness after curing was approximately 2.5 μm. Next, a 25 μm thick polyvinyl alcohol (PVA)-iodine polarizing film (polarizer) was attached to the coated surface. Next, a film with a thickness of 40 μm made of acetyl cellulose resin [trade name: "KC4CR-1", manufactured by Konica Minolta Opto Co., Ltd., transmittance of 49% at a wavelength of 300 nm, transmittance of 90% at a wavelength of 320 nm, transmittance at a wavelength of 350 nm [Transmittance 90%]] was subjected to corona discharge treatment on one side, and the adhesive listed in Table 1 was coated on the corona discharge treatment surface using a bar coater so that the thickness after curing was approximately 2.5 μm. did. On the coated surface, the polarizing film with the acetyl cellulose resin film produced above was stacked on the polarizing film side, and pressed and bonded using a bonding roll to obtain a laminate. This laminate was irradiated with an ultraviolet ray irradiation device equipped with a belt conveyor [the lamp used was "D Bulb" manufactured by Fusion UV Systems] from the acetyl cellulose resin film (thickness: 40 μm) side. A polarizing plate was produced by irradiating ultraviolet rays at a pressure of 200 mJ/cm ² (UVB) and then heating at a temperature of 90° C. for 1 minute to harden the adhesive layers on both sides.

(3) Evaluation of appearance of polarizing plate A sheet of 8 cm x 8 cm in size was cut out from the polarizing plate produced in (2) above. After this sheet was left overnight in an environment with a temperature of 23° C. and a relative humidity of 60%, the amount of curl of the sheet was measured. The amount of curl is determined by placing the curved sheet on a horizontal table so that it is convex downwards, and measuring the height from the table to each of the four corners of the sheet using a ruler. This is the average value of the point values. Based on the obtained curl amount, judgment was made according to the following criteria. The results are shown in Table 1.

<Evaluation criteria for the appearance of polarizing plates>
4: The amount of curl was less than 8 mm.
3: The amount of curl was 8 mm or more and less than 13 mm.
2: The amount of curl was 13 mm or more.
1: The polarizing plate curled into a cylindrical shape, or floating occurred between the protective film and the polarizer.

(4) Evaluation of peeling force (adhesion force) Corona discharge treatment was applied to the surface of the protective film made of triacetylcellulose resin in the obtained polarizing plate, and then a commercially available 25 μm thick (meta) film was applied to the corona discharge treated surface. An acrylic adhesive sheet was laminated to form a polarizing plate with an adhesive layer. A test piece with a width of 25 mm and a length of about 200 mm was cut from the obtained polarizing plate with an adhesive layer, and the adhesive layer surface thereof was bonded to soda glass. This sample was stored at a temperature of 80° C. and a relative humidity of 90% for 24 hours, and then stored overnight at a temperature of 23° C. and a relative humidity of 55%. Next, insert a cutter blade between the polarizing film and the protective film, peel off 30 mm from the end in the length direction, and test the peeled part with a universal tensile tester [manufactured by Shimadzu Corporation, product name "AG-1"] ] was grabbed with the grip part. The test piece in this state was tested in an atmosphere at a temperature of 23°C and a relative humidity of 55% according to JIS K 6854-2:1999 "Adhesives - Peel adhesion strength test method - Part 2: 180 degree peel". A 180 degree peel test was conducted at a gripping movement speed of 300 mm/min, and the average peeling force over a length of 170 mm excluding 30 mm of the grip portion was determined. The results are shown in Table 1.

(5) Formation of adhesive layer <Examples 1 to 10 and Comparative Example 1>
An organic solvent for a (meth)acrylic adhesive made by adding an isocyanate crosslinking agent and a silane coupling agent to a (meth)acrylic resin that is a copolymer of butyl acrylate, methyl acrylate, acrylic acid, and hydroxyethyl acrylate. The solution was applied to the release-treated surface of a 38-μm-thick separate film made of polyethylene terephthalate (manufactured by Lintec Corporation, product name "SP-PLR382052") using a die coater until the thickness after drying It was coated to a thickness of 20 μm to produce a sheet-like adhesive with a separate film. Next, the surface of the sheet-like adhesive obtained above opposite to the separate film (adhesive surface) was laminated to the cyclic polyolefin resin film surface of the polarizing plate prepared in (2) above using a laminator, and then the temperature was increased. A polarizing plate having an adhesive layer was obtained by curing for 7 days at 23° C. and a relative humidity of 65%.

(5) Formation of adhesive layer <Example 11>
An organic solvent for a (meth)acrylic adhesive made by adding an isocyanate crosslinking agent and a silane coupling agent to a (meth)acrylic resin that is a copolymer of butyl acrylate, methyl acrylate, acrylic acid, and hydroxyethyl acrylate. The solution was applied to the release-treated surface of a 38-μm-thick separate film made of polyethylene terephthalate (manufactured by Lintec Corporation, product name "SP-PLR382052") using a die coater until the thickness after drying It was coated to a thickness of 20 μm to produce a sheet-like adhesive with a separate film. Next, the surface of the sheet-like adhesive obtained above opposite to the separate film (adhesive surface) was laminated to the polyester resin film surface of the polarizing plate prepared in (2) above using a laminator, and then heated at a temperature of 23°C. After curing for 7 days at a relative humidity of 65%, a polarizing plate having an adhesive layer was obtained.

(5) Formation of adhesive layer <Example 12>
An organic solvent for a (meth)acrylic adhesive made by adding an isocyanate crosslinking agent and a silane coupling agent to a (meth)acrylic resin that is a copolymer of butyl acrylate, methyl acrylate, acrylic acid, and hydroxyethyl acrylate. The solution was applied to the release-treated surface of a 38-μm-thick separate film made of polyethylene terephthalate (manufactured by Lintec Corporation, product name "SP-PLR382052") using a die coater until the thickness after drying It was coated to a thickness of 20 μm to produce a sheet-like adhesive with a separate film. Next, the surface of the sheet-like adhesive obtained above opposite to the separate film (adhesive surface) was laminated to the acetyl cellulose resin film surface of the polarizing plate prepared in (2) above using a laminator, and then the temperature was increased. A polarizing plate having an adhesive layer was obtained by curing for 7 days at 23° C. and a relative humidity of 65%.

(6) Evaluation of wet heat durability of polarizing plate The polarizing plate with adhesive layer prepared in (5) above was cut into a size of 30 mm x 30 mm, the separate film was peeled off, and the exposed adhesive layer surface was placed on a glass substrate. Pasted. For the glass substrate, alkali-free glass manufactured by Corning under the trade name "Eagle XG" was used. The obtained optical laminate was measured for MD transmittance and TD transmittance in the wavelength range of 380 to 780 nm using a spectrophotometer with an integrating sphere (manufactured by JASCO Corporation, product name "V7100"). Calculate the single transmittance at the wavelength, and perform visibility correction using the 2-degree visual field (C light source) of JIS Z 8701:1999 "Color display method - XYZ color system and X ₁₀ Y ₁₀ Z ₁₀ color system", The luminosity-corrected single transmittance (Ty) before the durability test was determined. The optical laminate was set in a spectrophotometer with an integrating sphere so that the cyclic polyolefin resin film side of the polarizing plate was the detector side, and light entered from the glass substrate side.

Single transmittance is defined by the formula: (λ)=0.5×(Tp(λ)+Tc(λ)). Tp (λ) is the transmittance (%) of the optical laminate measured in parallel Nicol relationship with the linearly polarized light of the incident wavelength λ (nm), and Tc (λ) is the transmittance (%) of the incident wavelength λ (nm). This is the transmittance (%) of the optical laminate measured in the relationship between linearly polarized light and crossed Nicols.

Next, this optical laminate was placed in a moist heat environment with a temperature of 80°C and a relative humidity of 90% for 24 hours, and then placed in an environment with a temperature of 23°C and a relative humidity of 60% for 24 hours, and then subjected to the same method as before the durability test. Ty was determined after the durability test. Based on the Ty before and after the durability test, the increase rate of Ty was calculated based on the following formula, and determined based on the following criteria. The results are shown in Table 1.

Increase rate of Ty = {(Ty after durability test - Ty before durability test)/Ty before durability test} x 100

<Evaluation criteria for wet heat durability>
4: The rate of increase in single transmittance (ΔTy) was less than 6%.
3: The rate of increase in single transmittance (ΔTy) was 6% or more and less than 10%.
2: The rate of increase in single transmittance (ΔTy) was 10% or more and less than 80%.
1: The rate of increase in single transmittance (ΔTy) was 80% or more.

As shown in Table 1, it was confirmed that the polarizing plate obtained in Example was superior to the polarizing plate obtained in Comparative Example 1 in terms of adhesion, appearance, and moist heat durability. .

DESCRIPTION OF SYMBOLS 10... First protective film, 15... First adhesive layer, 20... Second protective film, 25... Second adhesive layer, 30... Polarizer

Claims (7)

A polarizing plate comprising a polarizer and a protective film laminated on at least one surface of the polarizer via an adhesive layer, the adhesive layer comprising a cationic polymerizable compound, a first acid generator, and a protective film laminated on at least one surface of the polarizer. A cured product of an adhesive containing an acid generator and a second acid generator,
the adhesive does not contain filler;
The first acid generator is an ionic compound having a curing temperature of less than 120°C, and the counter anion constituting the ionic compound is represented by the following formula (1).

[Wherein, R ¹ is a C _6-14 aryl group which may have a substituent or a C _3-14 aromatic heterocyclic group which may have a substituent, and R ² to R ⁴ are independently of each other, they are a C _1-18 alkyl group, a C _6-14 aryl group which may have a substituent, or a C _3-14 aromatic heterocyclic group which may have a substituent; The groups include C _1-18 alkyl group, halogenated C _1-8 alkyl group, C _2-18 alkenyl group, C _2-18 alkynyl group, C _6-14 aryl group, C _3-14 aromatic heterocyclic group, nitro group, hydroxyl group, cyano group, alkoxy group or aryloxy group represented by -OR ⁵ , acyl group represented by R ⁶ CO-, acyloxy group represented by R ⁷ COO-, represented by -SR ⁸ An alkylthio group or an arylthio group, an amino group represented by -NR ⁹ R ¹⁰ , or a halogen atom, and R ⁵ to R ⁸ are a C _1-8 alkyl group, a C _6-14 aryl group, or a C _3-14 aromatic group. and R ⁹ and R ¹⁰ are a hydrogen atom, a C _1-8 alkyl group, a C _6-14 aryl group, or a C _3-14 aromatic heterocyclic group]
Anion represented by or the following formula (2)

[In the formula, Rf represents the same or different alkyl group in which 80% or more of hydrogen atoms are substituted with fluorine atoms, and a is an integer from 1 to 5]
It is an ionic compound that is an anion represented by
The second acid generator is an ionic compound that has a curing temperature of 120° C. or higher and generates acid with active energy rays,
The proportion of the second acid generator is 0.5 parts by mass or more with respect to 100 parts by mass of the cationic polymerizable compound,
A polarizing plate, wherein the ratio of the total amount of the first acid generator and the second acid generator is more than 0.5 parts by mass and not more than 20 parts by mass with respect to 100 parts by mass of the cationically polymerizable compound. The first acid generator is expressed by the following formula (3)

[In the formula, R ¹¹ and R ¹² independently represent an alkyl group, an aralkyl group, an aryl group, or an aromatic heterocyclic group, R ¹³ represents a phenyl group which may have a substituent, and X ^- is an anion represented by the above formula (1) or formula (2)]
The polarizing plate according to claim 1 , which is an ionic compound represented by: 3. The polarizing plate according to claim 1, wherein the counter anion of the second acid generator is an anion represented by the formula (1) or the formula ( 2 ), or PF ₆ ^- . 4. The polarizing plate according to claim 1 , wherein the counter cation of the second acid generator is a sulfonium cation. The polarizing plate according to any one of claims 1 to 4 , wherein the cationic polymerizable compound contains at least one compound selected from the group consisting of epoxy compounds, oxetane compounds, and vinyl compounds. Any one of claims 1 to 5 , wherein the protective film contains at least one resin selected from the group consisting of cellulose resin, (meth)acrylic resin, polyolefin resin, polyester resin, and polycarbonate resin. Polarizing plate as described. A method for manufacturing a polarizing plate according to any one of claims 1 to 6 , comprising:
(a) a step of applying an adhesive to a polarizer and/or a protective film; (b) a step of laminating a polarizer and a protective film; (c) a step of irradiating the laminate obtained in step (b) with active energy rays; and (d) then heating the laminate.

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