CN109661601B - Polarizing plate and method for manufacturing same - Google Patents

Abstract

The present invention provides a polarizing plate that exhibits excellent durability even in environments such as high temperature and high humidity, and a method for producing the same. A polarizing plate comprising a polarizer and a protective film laminated via an adhesive layer on at least one surface of the polarizer, the adhesive layer comprising a cationically polymerizable compound, a first acid generator, and a second A cured product of an acid generator adhesive, wherein 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) or (2) The ionic compound of the shown anion, and the said 2nd acid generator is an ionic compound which has a curing temperature of 120 degreeC or more, and which generate|occur|produces an acid by an active energy ray.

Description

Polarizing plate and method for manufacturing same

Technical Field

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

Background

As an adhesive used for assembling an optical component or the like, an adhesive containing a cationically polymerizable resin, a photopolymerization initiator, and a thermal polymerization initiator is known (patent documents 1 and 2). Such an adhesive has not only a curing action by light irradiation but also a curing action by heating, and therefore, a portion which becomes a shadow at the time of assembling an optical component or the like can be bonded, and thus, the adhesive can be used for assembling an optical material such as a semiconductor laser module.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2013-95881

Patent document 2: japanese patent laid-open publication No. 2003-96425

Disclosure of Invention

Problems to be solved by the invention

On the other hand, an adhesive is also used for a polarizing plate widely used in a liquid crystal display device and the like, and in general, a polarizing plate has a structure in which a protective film is laminated on one side or both sides of a polarizing plate via an adhesive. In recent years, polarizing plates have been used for various applications, for example, for mobile devices such as smart phones and tablet terminals, and are sometimes placed in a high-temperature or high-temperature and high-humidity environment.

Therefore, even under such an environment, it is required to suppress the floating, peeling, and the like at the interface between the adhesive and the polarizing plate or the protective film and to prevent the deterioration of the optical characteristics. In particular, due to the strong shrinkage stress of the polarizing plate in a high temperature environment, the adhesive used for the polarizing plate is required to have higher durability than the adhesive used for assembling general optical components and the like.

Accordingly, an object of the present invention is to provide a polarizing plate exhibiting excellent durability even under an environment such as high temperature and high humidity, and a method for producing the same.

Means for solving the problems

The present inventors have conducted intensive studies to solve the above problems, and as a result, have completed the present invention. That is, the present invention includes the following aspects.

[1] A polarizing plate comprising a polarizing plate and a protective film laminated on at least one surface of the polarizing plate via an adhesive layer, wherein the adhesive layer is a cured product of an adhesive containing a cationically polymerizable compound, a first acid generator and a second acid generator,

the first acid generator is an ionic compound having a curing temperature of less than 120 ℃ and a counter anion constituting the ionic compound is an anion represented by the following formula (1) or an anion represented by the following formula (2),

[ solution 1]

[ in the formula, R¹Is C optionally having a substituent_6-14Aryl or C optionally having substituents_3-14Aromatic heterocyclic radical, R²～R⁴Independently of one another are C_1-18Alkyl, C optionally having substituent(s)_6-14Aryl or C optionally having substituents_3-14An aromatic heterocyclic group, the above-mentioned substituent being C_1-18Alkyl, halo C_1-8Alkyl radical, C_2-18Alkenyl radical, C_2-18Alkynyl, C_6-14Aryl radical, C_3-14Aromatic heterocyclic group, nitro group, hydroxy group, cyano group, -OR⁵Alkoxy or aryloxy radicals shown, R⁶Acyl group represented by CO-R⁷Acyloxy group represented by COO-or-SR⁸Alkylthio or arylthio radicals, -NR⁹R¹⁰An amino group represented by the formula, or a halogen atom, the above-mentioned R⁵～R⁸Is C_1-8Alkyl radical, C_6-14Aryl or C_3-14An aromatic heterocyclic group, the above-mentioned R⁹And R¹⁰Is a hydrogen atom, C_1-8Alkyl radical, C_6-14Aryl or C_3-14An aromatic heterocyclic group.]

[ solution 2]

[(Rf)_aPF_6-a]^- (2)

[ in the formula, Rf represents identical or different alkyl groups in which 80% or more of hydrogen atoms are substituted by fluorine atoms, and a is an integer of 1 to 5. ]

The second acid generator is an ionic compound having a curing temperature of 120 ℃ or higher and generating an acid by an active energy ray.

[2] The polarizing plate according to [1], wherein the adhesive layer is an adhesive layer cured by irradiating the adhesive with an active energy ray and then heating.

[3] The polarizing plate according to [1] or [2], wherein the first acid generator is an ionic compound represented by the following formula (3).

[ solution 3]

[ in the formula, R¹¹And R¹²Independently of one another, an alkyl group, an aralkyl group, an aryl group or an aromatic heterocyclic group, R¹³Represents an optionally substituted phenyl group, X^-Is [1]]The anion represented by the formula (1) or the formula (2).]

[4]According to [1]～[3]The polarizing plate according to any one of the above items, wherein the counter anion of the second acid generator is an anion represented by the above formula (1) or the above formula (2), or PF₆ ^-。

[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 comprises at least 1 compound selected from an epoxy compound, an oxetane compound and a vinyl compound.

[7] The polarizing plate according to any one of [1] to [6], wherein the protective film comprises at least 1 resin selected from a cellulose-based resin, (meth) acrylic resin, polyolefin-based resin, polyester-based resin, and polycarbonate-based resin.

[8] A method for producing a polarizing plate according to any one of [1] to [7], comprising:

(a) coating an adhesive on the polarizing plate and/or the protective film;

(b) a step of laminating a polarizing plate and a protective film;

(c) irradiating the laminate obtained in the step (b) with an active energy ray; and

(d) then, the laminate is heated.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a polarizing plate having excellent durability even under an environment such as high temperature and high humidity can be provided.

Drawings

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

Detailed Description

< polarizing plate >

The polarizing plate of the present invention includes a polarizing plate and a protective film laminated on at least one surface of the polarizing plate via an adhesive layer.

Fig. 1 is a schematic cross-sectional view showing an example of the layer structure of the polarizing plate of the present invention. The polarizing plate shown in fig. 1 includes a first protective film 10, a first adhesive layer 15, a polarizing plate 30, a second adhesive layer 25, and a second protective film 20 in this order. That is, the first protection film 10 is laminated on one surface of the polarizing plate 30 via the first adhesive layer 15, and the second protection film 20 is laminated on the other surface of the polarizing plate 30 via the second adhesive layer 25.

The polarizing plate of the present invention may include other layers than those described above, without being limited to the example of fig. 1. Specific examples of other layers include: an adhesive layer laminated on an outer surface of the first protective film 10 and/or the second protective film 20; a release film (also referred to as a "release film") laminated on an outer surface of the pressure-sensitive adhesive layer; a protective film (also referred to as a "surface protective film") laminated on an outer surface of the first protective film 10 and/or the second protective film 20; and an optical functional film laminated on the outer surface of the first protective film 10 and/or the second protective film 20 via an adhesive layer or a pressure-sensitive adhesive layer.

The polarizing plate of the present invention may be a long polarizing plate having the above-described layer structure or a wound roll thereof, a polarizing plate sheet cut from the long polarizing plate or the wound roll, or a polarizing plate sheet cut into a smaller size.

In the present specification, the term "durability" means: for example, in a high-temperature environment, a high-temperature and high-humidity environment, an environment in which high temperature and low temperature are repeated, or the like, a property of suppressing the floating or peeling at the interface between the adhesive layer and the polarizing plate or the protective film adjacent thereto (sometimes referred to as peeling resistance), a property of suppressing the deterioration of optical properties (sometimes referred to as deterioration resistance), and a property of suppressing the warping (or curling) of the polarizing plate (sometimes referred to as curling resistance), or the like.

[1] Adhesive layer

The adhesive layer constituting the polarizing plate of the present invention is a cured product of an adhesive containing a predetermined cationic polymerizable compound, a first acid generator and a second acid generator described below, and is preferably a cured product cured by irradiation with an active energy ray and heating.

(1) Cationically polymerizable compound

The cationically polymerizable compound is preferably a compound or oligomer which is cured by a cationic polymerization reaction by irradiation with active energy rays (for example, ultraviolet rays, visible light, electron rays, X-rays, and the like) and heating. Examples of the cationically polymerizable compound include an epoxy compound having 1 or more epoxy groups in the molecule, an oxetane compound having 1 or more oxetane rings in the molecule, and a vinyl compound. These cationically polymerizable compounds may be used alone or in combination of 2 or more. Among them, at least 1 compound selected from the group consisting of epoxy compounds, oxetane compounds and vinyl compounds is preferable, and epoxy compounds and oxetane compounds are particularly preferable. Examples of the epoxy compound include alicyclic epoxy compounds, aliphatic epoxy compounds, aromatic epoxy compounds, and hydrogenated epoxy compounds, and alicyclic epoxy compounds and aliphatic epoxy compounds are preferable from the viewpoint of adhesiveness and curing speed. The number of epoxy groups present in the molecule of the epoxy compound may be, for example, 1, preferably 2 or more, and particularly 2. When a bifunctional epoxy compound (the number of epoxy groups is 2) is used, adhesion to a polarizing plate is high even with respect to a shrinkage stress of the polarizing plate, and thus, it is advantageous for forming a polarizing plate having excellent peeling resistance and the like.

The alicyclic epoxy compound may be a compound having 1 or more epoxy groups bonded to the alicyclic ring in the molecule. The "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.

[ solution 4]

The alicyclic epoxy compound may be a compound obtained by removing (CH) of the formula (5)₂)_mA compound in which 1 or more hydrogen atoms in the form of (A) are bonded to other chemical structures. Specifically, in the alicyclic epoxy compound, the (CH) of the formula (5) is removed₂)_mWherein the hydrogen is a linear or branched alkylene group (e.g., linear or branched C)_1-12Alkylene) is bonded to 1 or more compounds of formula (5). wherein-CH constituting the above-mentioned linear or branched alkylene group₂-may be replaced by-O-or-CO-. In addition, (CH)₂)_mWherein 1 or more hydrogen atoms in the above-mentioned group may be appropriately substituted by a linear or branched alkyl group such as a methyl group or an ethyl group. Among them, from the viewpoint of adhesiveness and curing speed, an alicyclic epoxy compound having an epoxycyclopentane structure [ m is 3 in the above formula (5) ] and an epoxycyclohexane structure [ m is 4 in the above formula (5) ] is advantageous.

Specific examples of suitable difunctional alicyclic epoxy compounds (sometimes referred to as difunctional alicyclic epoxy compounds) are described below. Here, first, compound names are listed, and then, chemical formulae corresponding to the respective compound names are shown, and the same symbols are given to the compound names and the chemical formulae corresponding thereto.

1A: 3, 4-epoxycyclohexanecarboxylic acid-3, 4-epoxycyclohexylmethyl ester,

2A: 3, 4-epoxy-6-methylcyclohexanecarboxylic acid-3, 4-epoxy-6-methylcyclohexylmethyl ester,

3A: ethylene bis (3, 4-epoxycyclohexanecarboxylate),

4A: bis (3, 4-epoxycyclohexylmethyl) adipate,

5A: bis (3, 4-epoxy-6-methylcyclohexylmethyl) adipate,

6A: diethylene glycol bis (3, 4-epoxycyclohexylmethyl ether),

7A: ethylene glycol bis (3, 4-epoxycyclohexylmethyl ether),

8A: 2, 3, 14, 15-diepoxy-7, 11, 18, 21-tetraoxatrispiro [5.2.2.5.2.2] heneicosane,

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.

[ solution 5]

[ solution 6]

As the aliphatic epoxy compound, there may be mentioned: compounds having at least 1 oxirane ring (3-membered cyclic ether) bonded to an aliphatic carbon atom in the molecule, for example, monofunctional aliphatic epoxy compounds (e.g., linear or branched C-chain compounds such as butyl glycidyl ether and 2-ethylhexyl glycidyl ether)_2-12Alkyl glycidyl ethers); difunctional aliphatic epoxy Compounds (e.g., straight-chain or branched-chain C-s such as 1, 4-butanediol diglycidyl ether, 1, 6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, etc_2-12Cyclic alkyl diglycidyl ethers such as alkyl diglycidyl ether and 1, 4-cyclohexanedimethanol diglycidyl ether are preferred to be linear or branched C_2-6Alkyl diglycidyl ethers, etc.); more than trifunctionalAliphatic epoxy Compound (e.g., trimethylolpropane triglycidyl Ether, pentaerythritol tetraglycidyl Ether, and the like C)_1-12Alkyl glycidyl ethers, etc.); epoxy compounds having 1 epoxy group directly bonded to an alicyclic ring and having an oxirane ring bonded to an aliphatic carbon atom, such as 4-vinylcyclohexene dioxide and limonene dioxide.

A suitable difunctional aliphatic epoxy compound (sometimes referred to as a difunctional aliphatic epoxy compound) having 2 epoxy groups present in the molecule can be represented by, for example, the following formula (6).

[ solution 7]

In the 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 carbon atoms in total and having an ether bond, or a C6-18 2-valent hydrocarbon group having an alicyclic structure, preferably an alkylene group having 2 to 6 carbon atoms.

The aliphatic diepoxy compound represented by the above formula (6) is specifically a diglycidyl ether of an alkane diol, a diglycidyl ether of an oligoalkylene diol having a repetition number of about 4, or a diglycidyl ether of an alicyclic diol.

Specific examples of diols (glycols) which can form the aliphatic diepoxy compound represented by the above formula (6) are listed below. As the alkane diol, there are included, for example, 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, 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, and the like. As the oligoalkylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and the like are included. Examples of the alicyclic diol include cyclohexanediol, cyclohexanedimethanol, and the like.

The aromatic epoxy compound is a compound having an aromatic ring and an epoxy group in a molecule. Specific examples thereof include: bisphenol-type epoxy compounds such as diglycidyl ether of bisphenol a, diglycidyl ether of bisphenol F, diglycidyl ether of bisphenol S, and oligomers thereof; novolac type epoxy resins such as phenol novolac type epoxy resin, cresol novolac type epoxy resin, hydroxybenzaldehyde phenol novolac type epoxy resin, and the like; polyfunctional epoxy compounds such as glycidyl ether of 2, 2 ', 4, 4' -tetrahydroxydiphenylmethane and glycidyl ether of 2, 2 ', 4, 4' -tetrahydroxybenzophenone; and polyfunctional epoxy resins such as epoxidized polyvinylphenol.

The hydrogenated epoxy compound may be a glycidyl ether of a polyol having an alicyclic ring, or may be a compound obtained by subjecting an aromatic ring to a hydrogenation reaction selectively in the presence of a catalyst under pressure with respect to an aromatic polyol and subjecting the thus obtained nuclear hydrogenated polyhydroxy compound to glycidyl etherification. Specific examples of the aromatic polyol include: bisphenol compounds such as bisphenol a, bisphenol F, and bisphenol S; phenol novolac resins such as phenol novolac resin, cresol novolac resin, hydroxybenzaldehyde phenol novolac resin, and the like; and polyfunctional compounds such as tetrahydroxydiphenylmethane, tetrahydroxybenzophenone, and polyvinyl phenol. Glycidyl ether can be produced by reacting epichlorohydrin with an alicyclic polyol obtained by hydrogenating an aromatic ring of an aromatic polyol. Among these hydrogenated epoxy compounds, hydrogenated diglycidyl ethers 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, and particularly preferably 100 to 300 g/equivalent. When the epoxy equivalent is within the above range, a polarizing plate having excellent peeling resistance can be formed.

The proportion of the epoxy compound may be 40 to 100 parts by mass, preferably 60 to 99 parts by mass, more preferably 80 to 98 parts by mass, particularly 90 to 97 parts by mass, relative to the cationically polymerizable compound. When the content is in these ranges, the adhesiveness (or adhesiveness) is favorable. In addition, from the viewpoint of optimizing the curing speed, improving the adhesion, and the like, an alicyclic epoxy compound and an aliphatic epoxy compound may be used in combination. In this case, the ratio (mass ratio) of the alicyclic epoxy compound to the aliphatic epoxy compound may be, for example, 95/5 to 5/95, preferably 90/10 to 10/90, more preferably 80/20 to 20/80, and still more preferably 75/25 to 30/70. When the content is in this range, it is advantageous for forming an adhesive layer having high adhesiveness and durability.

The oxetane compound which is one of the cationically polymerizable compounds may be a compound containing 1 or more oxetanes (hexyloxy groups) in the molecule, and examples thereof include monofunctional oxetane compounds [ e.g., 3-ethyl-3-hydroxymethyloxetane (sometimes referred to as oxetanol), 2-ethylhexyloxetane, 1, 4-bis { (3-ethyloxetan-3-yl) methoxy } methyl ] benzene (sometimes referred to as xylylene dioxyoxetane), 3-ethyl-3- (phenoxymethyl) oxetane, 3- (cyclohexyloxy) methyl-3-ethyloxetane; a bifunctional oxetane compound [ e.g., 3-ethyl-3 { (3-ethyloxetan-3-yl) methoxy } methyl ] oxetane, and the like. Among these oxetane compounds, difunctional oxetane compounds are preferable from the viewpoint of adhesiveness and curing speed. The oxetane compound may be used as a 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 from the viewpoint that curability, peeling resistance, curl resistance, and the like can be improved in some cases. In this case, the proportion of the oxetane compound may be, for example, 0.5 to 70 parts by mass, preferably 1 to 30 parts by mass, and more preferably 3 to 10 parts by mass, based on 100 parts by mass of the epoxy compound. The proportion of the oxetane compound is favorably set to an upper limit or less from the viewpoint of adhesiveness (or adhesiveness), and favorably set to a lower limit or more from the viewpoint of durability against high temperatures and the like.

Examples of the vinyl compound that can be used as the cationically polymerizable compound include aromatic, aliphatic, and alicyclic vinyl ether compounds, and specific examples thereof include: vinyl ethers of alkyl or alkenyl alcohols having 5 to 20 carbon atoms such as n-amyl vinyl ether, isoamyl vinyl ether, n-hexyl vinyl ether, n-octyl vinyl ether, 2-ethylhexyl vinyl ether, n-dodecyl vinyl ether, stearyl vinyl ether, oleyl vinyl ether and the like; hydroxyl-containing vinyl ethers such as 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether and 4-hydroxybutyl vinyl ether; vinyl ethers of monohydric alcohols having an aliphatic ring or an aromatic ring, such as cyclohexyl vinyl ether, 2-methylcyclohexyl vinyl ether, cyclohexyl methyl vinyl ether, and benzyl vinyl ether; mono-to polyvinyl ethers of polyhydric alcohols such as glycerol monovinyl ether, 1, 4-butanediol divinyl ether, 1, 6-hexanediol divinyl ether, neopentyl glycol divinyl ether, pentaerythritol tetravinyl ether, trimethylolpropane divinyl ether, trimethylolpropane trivinyl ether, 1, 4-dihydroxycyclohexane monovinyl ether, 1, 4-dihydroxycyclohexane divinyl ether, 1, 4-dihydroxymethylcyclohexane monovinyl ether, 1, 4-dihydroxymethylcyclohexane divinyl ether, and the like; polyalkylene glycol mono-divinyl ethers such as diethylene glycol divinyl ether, 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 a 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. The vinyl compound may be used in combination, because the viscosity of the adhesive is reduced and the curing rate can be improved.

The cationic polymerization adhesive may further contain other cationic polymerizable compounds than the above, such as a cyclic lactone compound, a cyclic acetal compound, a cyclic thioether compound, and a Spiro orthoester (Spiro Ortho Ester) compound.

(2) First acid generator

The first acid generator is an ionic compound which generates an acid at a predetermined temperature and can polymerize the cationically polymerizable compound, and the curing temperature of the first acid generator is less than 120 ℃. Here, the "curing temperature" in the present invention indicates a temperature at which the heat amount of a Differential Scanning Calorimeter (DSC) reaches a maximum, in a curable composition obtained by adding 1 part by mass (solid content) of a first acid generator to 100 parts by mass of 3, 4-epoxycyclohexanecarboxylic acid-3 ', 4' -epoxycyclohexylmethyl ester (product name "CEL 2021P" manufactured by xylonite corporation) as a standard substance, measured by the method described in the item "measurement of curing temperature" in example. The first acid generator may have curability by active energy rays, as long as it has the above properties. That is, the acid generator may be an acid generator that generates a predetermined amount of acid by irradiating the adhesive with active energy rays.

The curing temperature may be, for example, 50 to 115 ℃, preferably 70 to 110 ℃, more preferably 90 to 105 ℃, particularly preferably 95 to 105 ℃, and may be, for example, preferably 95 to 117 ℃, more preferably 95 to 115 ℃.

When the amount is within the above range, the cationically polymerizable compound is easily cured, and therefore, is advantageous from the viewpoint of durability of the polarizing plate, and is also advantageous in terms of appearance because the heating temperature is low.

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) or an anion represented by the following formula (2).

[ solution 8]

[ in the formula, R¹Is C optionally having a substituent_6-14Aryl or C optionally having substituents_3-14Aromatic heterocyclic radical, R²～R⁴Independently of each otherIs C_1-18Alkyl, C optionally having substituent(s)_6-14Aryl or C optionally having substituents_3-14An aromatic heterocyclic group, the above-mentioned substituent being C_1-18Alkyl, halo C_1-8Alkyl radical, C_2-18Alkenyl radical, C_2-18Alkynyl, C_6-14Aryl radical, C_3-14Aromatic heterocyclic group, nitro group, hydroxy group, cyano group, -OR⁵Alkoxy or aryloxy radicals shown, R⁶Acyl group represented by CO-R⁷Acyloxy group represented by COO-or-SR⁸Alkylthio or arylthio radicals, -NR⁹R¹⁰An amino group represented by the formula, or a halogen atom, the above-mentioned R⁵～R⁸Is C_1-8Alkyl radical, C_6-14Aryl or C_3-14An aromatic heterocyclic group, the above-mentioned R⁹And R¹⁰Is a hydrogen atom, C_1-8Alkyl radical, C_6-14Aryl or C_3-14Aromatic heterocyclic radical]

[ solution 9]

[(Rf)_aPF_6-a]^- (2)

[ in the formula, Rf represents identical or different alkyl groups in which 80% or more of hydrogen atoms are substituted by fluorine atoms, and a is an integer of 1 to 5. ]

In R of the above formula (1)²～R⁴In as C_1-18Examples of the alkyl group include: linear C such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-octyl, n-decyl, n-dodecyl, and n-tetradecyl_1-18Alkyl, preferably straight-chain C_1-8An alkyl group; branched C such as isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl, tert-pentyl, isohexyl, 2-ethylhexyl, and 1, 1, 3, 3-tetramethylbutyl_1-18Alkyl, preferably branched C_1-8An alkyl group; c such as cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl_3-18Cycloalkyl, preferably C_3-8A cycloalkyl group; and crosslinked cyclic alkyl groups such as norbornyl, adamantyl, and pinanyl (pinanyl).

In R of the above formula (1)¹～R⁴In as C_6-14Examples of the aryl group include: monocyclic C such as phenyl_6-14An aryl group; naphthyl, anthryl, phenanthrylCondensed polycyclic C groups such as aryl, anthraquinone, fluorenyl, naphthoquinone and the like_6-14Aryl, and the like.

In R of the above formula (1)¹～R⁴In as C_3-14Aromatic heterocyclic groups, there may be mentioned: monocyclic C such as thienyl, furyl, pyranyl, pyrrolyl, oxazolyl, thiazolyl, pyridyl, pyrimidinyl, pyrazinyl and the like_3-14A heterocycle; a condensed polycyclic type C such as indolyl, benzofuranyl, isobenzofuranyl, benzothienyl, isobenzothienyl, quinolyl, isoquinolyl, quinoxalinyl, quinazolinyl, carbazolyl, acridinyl, phenothiazinyl, phenazinyl, xanthenyl, thiazo, phenoxazinyl, phenoxathiyl, chromanyl, isochromanyl, coumarinyl, dibenzothienyl, xanthenoyl, thioxanthonyl, dibenzofuranyl, etc_6-14Heterocyclic ring or the like C_3-14Aromatic heterocyclic hydrocarbons, and the like. As C_3-14The aromatic heterocyclic group may be a monocyclic group C_3-5The 1-valent group formed by the heterocyclic ring may be a monocyclic C group_6-14Heterocyclic ring forming 1-valent group.

In addition, R in the above formula (1)¹～R⁴C in (1)_6-14Aryl or C_3-14The aromatic heterocyclic group may have a substituent (sometimes referred to as substituent (a)). Is described as R⁵～R¹⁰C of (A)_1-8Alkyl radical, C_6-14Aryl and C_3-14Examples of the aromatic heterocyclic group include the above-mentioned R¹～R⁴C as exemplified in (1)_1-8Alkyl radical, C_6-14Aryl or C_3-14An aromatic heterocyclic group.

Examples of the substituent (a) include: c_1-18Alkyl [ e.g. C as exemplified above_1-18Alkyl radicals and the like](ii) a Halogen substituted C_1-8Alkyl [ e.g., halogenated straight chain C such as trifluoromethyl, trichloromethyl, pentafluoroethyl, 2, 2, 2-trichloroethyl, 2, 2, 2-trifluoroethyl, 1-difluoroethyl, heptafluoro-n-propyl, 1-difluoro-n-propyl, 3, 3, 3-trifluoro-n-propyl, nonafluoro-n-butyl, 3, 3, 4, 4, 4-pentafluoro-n-butyl, perfluoro-n-pentyl, perfluoro-n-octyl_1-8An alkyl group; hexafluoroisopropyl, hexachloroisopropyl, hexafluoroisobutylHalogenated branched C such as mesityl and nonafluorot-butyl_1-8An alkyl group; halogenated C's such as pentafluorocyclopropyl, nonafluorocyclobutyl, perfluorocyclopentyl and perfluorocyclohexyl_3-8Cycloalkyl radicals](ii) a C having carbon atom such as perfluoroadamantyl group_7-12A halogenated cross-linked cyclic alkyl group; c_2-18Alkenyl [ 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, 2-methyl-2-propenyl, and the like, straight or branched C_2-18An alkenyl group; 2-cyclohexenyl, 3-cyclohexenyl, etc. C_2-18A cycloalkenyl group; styryl, cinnamyl, and the like C_2-18Arylalkenyl and the like]；C_2-18Alkynyl group [ e.g., ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 3-butynyl, 1-methyl-2-propynyl, 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, 1-decynyl, 2-dodecylynyl, 10-dodecyletc. straight-chain or branched-chain C.sub._2-18An alkynyl group; phenylethynyl group and the like C_2-18Arylalkynyl and the like]；C_6-14Aryl [ e.g., the aryl exemplified above, etc. ]]；C_3-14Aromatic heterocyclic group [ e.g. the above-exemplified aromatic heterocyclic group, etc. ]](ii) a A nitro group; a hydroxyl group; a cyano group; -OR⁵An alkoxy group represented by the formula [ e.g., C such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, n-pentoxy, isopentoxy, neopentoxy, 2-methylbutoxy, etc. ]_1-8Alkoxy and the like]；-OR⁵Aryloxy group [ phenoxy, naphthoxy, etc. ] C_6-14Aryloxy group and the like]；-COR⁶An acyl group represented by (e.g. C such as acetyl, propionyl, butyryl, valeryl, benzoyl and the like)_1-8Alkylcarbonyl or C_6-14Aryl carbonyl group and the like]；-COOR⁷Acyloxy group [ e.g. acetoxy, butyryloxy, benzoyloxy, etc. ] C_1-8Alkylcarbonyloxy or C_6-14Arylcarbonyloxy and the like]；-SR⁸Alkylthio as shown [ e.g. methylthio, ethylthio, butylthio, hexylthio, cyclohexylthio, etc. ] C_1-8Alkylthio group and the like]、-SR⁸Arylthio group [ e.g. phenylthio, naphthylthio etc. C_6-14Arylthio and the like]；-NR⁹R¹⁰An amino group represented by the formula [ e.g., an amino group such as a methylamino group, an ethylamino group, a propylamino group, a dimethylamino group, a diethylamino group, a methylethylamino group, a dipropylamino group, a piperidyl group, etc. ]](ii) a Halogen atom [ e.g. fluorine atom, chlorine atom, bromine atom, iodine atom]And the like.

Among these substituents (A), halogenated C is preferred_1-8Alkyl groups, halogen atoms, nitro groups, cyano groups, and the like. In particular, from the viewpoint of polymerizability and curability of the cationically polymerizable compound, fluorine atom and fluorinated C are preferable_1-8An alkyl group.

R¹Preferably C optionally having a substituent_6-14Aryl, more preferably optionally having a halogen atom or a halogenated C_1-8C of alkyl_6-14And (4) an aryl group.

R²And R³Each independently preferably represents C optionally having a substituent_6-14Aryl, more preferably optionally having a halogen atom or a halogenated C_1-8C of alkyl_6-14And (4) an aryl group.

R⁴Preferably C_1-18Alkyl or C optionally having substituent_6-14And (4) an aryl group.

Preferably, R is²And R³Are identical radicals, more preferably R¹～R³Are identical radicals, it being further preferred for R to be¹～R⁴All are the same group.

Preferred examples of the counter anion in the formula (1) include: r¹～R⁴Anions each of pentafluorophenyl; r¹～R⁴Anions that are each 3, 5-bis (trifluoromethyl) phenyl; r¹～R⁴Anions of 3, 4, 5-trifluorophenyl, respectively; r¹～R³Are each tetrafluorophenyl, and R⁴An anion which is phenyl; r¹～R³Are each tetrafluorophenyl, and R⁴The anion of a butyl group, and the like.

In the above formula (2), examples of the alkyl group of Rf includeAlkyl groups of (2), and the like. Particularly preferred is C such as methyl, ethyl, propyl or butyl_1-8An alkyl group. In the formula (2), a may be an integer of 1 to 5, preferably an integer of 2 to 4.

Examples of the counter cation constituting the first acid generator of the present invention include sulfonium (e.g., triarylsulfonium cation such as triphenylsulfonium cation and 4, 4' -bis (diphenylsulfonium) diphenylsulfide cation), iodonium (e.g., diaryliodonium cation such as diphenyliodonium cation), diazonium (e.g., benzenediazonium cation), oxonium, ammonium, and phosphonium. Among them, sulfonium and iodonium are preferable, and sulfonium is particularly preferable from the viewpoint of polymerization reactivity.

The first acid generator of the present invention has an anion represented by formula (1) or (2) in which the acidity of the conjugate acid is high as a counter anion, and therefore, can accelerate curing of the cationically polymerizable compound by heating, and can form a polarizing plate excellent in peeling resistance and deterioration resistance even under high temperature and high humidity. In particular, the anion represented by the formula (1) can effectively promote curing. In addition, with antimonate anions (e.g. SbF)₆ ^-) The anion represented by the formula (1) or (2) is more suitable than the anion represented by the formula (1) or (2) in terms of safety.

A preferred embodiment of the first acid generator of the present invention includes an ionic compound represented by the following formula (3).

[ solution 10]

[ in the formula, R¹¹And R¹²Independently of one another, an alkyl group, an aralkyl group, an aryl group or an aromatic heterocyclic group, R¹³Represents an optionally substituted phenyl group, X^-Is an anion represented by the above formula (1) or the above formula (2).]

In R of the above formula (3)¹¹And R¹²In (1), examples of the alkyl group include the above-mentioned R²～R⁴Examples of the aralkyl group include the alkyl groups exemplified in (1) and C such as benzyl, 2-methylbenzyl, 1-naphthylmethyl and 2-naphthylmethyl_6-10Aryl radical C_1-8Alkyl, etc., examples of the aryl group include the above-mentioned R¹～R⁴The aryl group exemplified in (1), and the like. Examples of the aromatic heterocyclic group include the above-mentioned R¹～R⁴The aromatic heterocyclic group exemplified in (1), and the like. R¹³The phenyl group in (1) may be substituted with a substituent (B).

As R¹¹And R¹²The alkyl group of (1) is preferably a C group such as a methyl group, an ethyl group, a propyl group, a butyl group, or a pentyl group_1-8Alkyl, more preferably C_1-4An alkyl group. As R¹¹And R¹²Aralkyl of (2), preferably benzyl, naphthylbenzyl, as R¹¹And R¹²The aryl group of (2) is preferably phenyl, naphthyl, etc.

Examples of the substituent (B) include: alkoxy [ e.g., methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy, hexyloxy, decyloxy, dodecyloxy, octadecyloxy, etc. ] straight-chain or branched C_1-18Alkoxy and the like](ii) a Aryl [ e.g. phenyl, tolyl, dimethylphenyl, naphthyl, etc. C_6-10Aryl radical, C_1-5Alkyl radical C_6-10Aryl radicals and the like](ii) a Aromatic heterocyclic group (C such as thienyl, furyl, pyrrolyl, indolyl)_3-14Aromatic heterocyclic groups); aryloxy [ e.g. phenoxy, naphthyloxy, etc. C_6-10Aryloxy group and the like](ii) a Alkylcarbonyl [ e.g. acetyl, propionyl, butyryl, 2-methylpropionyl, heptanoyl, 2-methylbutyryl, 3-methylbutyryl, octanoyl, decanoyl, dodecanoyl and octadecanoyl group C_2-18Alkylcarbonyl and the like](ii) a Arylcarbonyl [ e.g. benzoyl, naphthoyl, etc. C_7-11Aryl carbonyl group and the like](ii) a Aralkylcarbonyl [ e.g. benzylcarbonyl, 2-methylbenzylcarbonyl, 1-naphthylmethylcarbonyl, 2-naphthylmethylcarbonyl, etc. ] C_6-10Aryl radical C_1-8Alkylcarbonyl and the like](ii) a Alkoxycarbonyl [ e.g., methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, isopropoxycarbonyl, butoxycarbonyl, isobutoxycarbonyl, sec-butoxycarbonyl, tert-butoxycarbonyl, octyloxycarbonyl, tetradecyloxycarbonyl, octadecyloxycarbonyl, etc. ] straight-chain or branched C_2-19Alkoxycarbonyl group and the like](ii) a Aryloxy carbonyl [ benzene ]Oxycarbonyl and naphthyloxycarbonyl group and the like C_7-11Aryloxycarbonyl and the like]And the like.

Examples of the substituent (B) include: aralkyloxycarbonyl [ e.g. benzyloxycarbonyl, 2-methylbenzyloxycarbonyl, 1-naphthylmethyloxycarbonyl, 2-naphthylmethyloxycarbonyl, etc. ] C_6-10Aryl radical C_1-8An alkoxycarbonyl group; alkylcarbonyloxy [ e.g., C such as acetoxy, ethylcarbonyloxy, propylcarbonyloxy, isopropylcarbonyloxy, butylcarbonyloxy, isobutylcarbonyloxy, sec-butylcarbonyloxy, tert-butylcarbonyloxy, octylcarbonyloxy, tetradecylcarbonyloxy, octadecylcarbonyloxy_2-19Alkylcarbonyloxy and the like](ii) a Arylcarbonyloxy [ e.g. benzoyloxy, naphthoyloxy and like C_7-11Arylcarbonyloxy group of (A), and the like]And aralkylcarbonyloxy [ e.g., benzylcarbonyloxy, 2-methylbenzylcarbonyloxy, 1-naphthylmethylcarbonyloxy, 2-naphthylmethylcarbonyloxy, etc. ] C_6-10Aryl radical C_1-8Alkylcarbonyl and the like]And alkoxycarbonyloxy [ e.g., methoxycarbonyloxy, ethoxycarbonyloxy, propoxycarbonyloxy, isopropoxycarbonyloxy, butoxycarbonyloxy, isobutoxycarbonyloxy, sec-butoxycarbonyloxy, tert-butoxycarbonyloxy, octyloxycarbonyloxy, tetradecyloxycarbonyloxy and octadecyloxycarbonyloxy ] straight-chain or branched C_2-19Alkoxycarbonyloxy and the like](ii) a Aryloxy-carbonyloxy group [ e.g. C such as phenoxycarbonyloxy and naphthyloxy-carbonyloxy_7-11Aryloxycarbonyloxy and the like](ii) a Aralkyloxycarbonyloxy [ e.g. benzyloxycarbonyloxy, 2-methylbenzyloxycarbonyloxy, 1-naphthylmethyloxycarbonyloxy, 2-naphthylmethyloxycarbonyloxy, etc. ] C_6-10Aryl radical C_1-8Alkoxycarbonyloxy and the like](ii) a Arylthiocarbonyl [ e.g. C for phenylthiocarbonyl and naphthyloxy-thiocarbonyl_7-11Arylthiocarbonyl, etc](ii) a Arylthio [ 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-hydroxyphenylthioThio, 2-methoxyphenylthio, 4-methoxyphenylthio, 1-naphthylthio, 2-naphthylthio, 4- [4- (phenylthio) benzoyl]Phenylthio, 4- [4- (phenylthio) phenoxy]Phenylthio, 4- [4- (phenylthio) phenyl]C.C. Pat. Nos. 4- (phenylthio) phenylthio, 4-benzoylphenylthio, 4-benzoyl-2-phenylthio, 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) phenylthio and the like_6-20Arylthio and the like](ii) a Alkylthio [ e.g., methylthio, ethylthio, propylthio, isopropylthio, butylthio, isobutylthio, sec-butylthio, tert-butylthio, pentylthio, isopentylthio, neopentylthio, tert-pentylthio, octylthio, decylthio, dodecylthio, isooctadecylthio, etc., straight-chain or branched C_1-18Alkylthio group and the like]And the like.

Further, as the substituent (B), there may be mentioned: heterocyclic hydrocarbon groups [ e.g., C-groups such as thienyl, furyl, pyranyl, pyrrolyl, oxazolyl, thiazolyl, pyridyl, pyrimidinyl, pyrazinyl, indolyl, benzofuryl, benzothienyl, quinolyl, isoquinolyl, quinoxalinyl, quinazolinyl, carbazolyl, acridinyl, phenothiazinyl, phenazinyl, xanthenyl, thienyl, phenoxazinyl, phenoxathiyl, chromanyl, isochromanyl, dibenzothienyl, xanthenonyl, thioxanthone, and dibenzofuryl_3-20Aryl heterocyclic hydrocarbon (aromatic heterocyclic group) and the like](ii) a Alkylsulfinyl [ e.g., methylsulfinyl, ethylsulfinyl, propylsulfinyl, isopropylsulfinyl, butylsulfinyl, isobutylsulfinyl, sec-butylsulfinyl, tert-butylsulfinyl, pentylsulfinyl, isopentylsulfinyl, neopentylsulfinyl, tert-pentylsulfinyl, octylsulfinyl, and isooctadecylsulfinyl ] and the like_1-18Alkylsulfinyl and the like](ii) a Arylsulfinyl [ e.g. phenylsulfinyl, tolylsulfinyl and naphthylSulfinyl radical or the like C_6-10Arylsulfinyl and the like](ii) a Straight-chain or branched C such as alkylsulfonyl [ e.g., methylsulfonyl, ethylsulfonyl, propylsulfonyl, isopropylsulfonyl, butylsulfonyl, isobutylsulfonyl, sec-butylsulfonyl, tert-butylsulfonyl, pentylsulfonyl, isopentylsulfonyl, neopentylsulfonyl, tert-pentylsulfonyl, octylsulfonyl, octadecylsulfonyl ] or the like_1-18Alkylsulfonyl and the like](ii) a Arylsulfonyl [ e.g. phenylsulfonyl, tolylsulfonyl (tosyl) and naphthylsulfonyl, etc. ] C_6-10Arylsulfonyl, etc](ii) a A hydroxy (poly) alkyleneoxy group [ e.g., a hydroxy (poly) alkyleneoxy group having 1 to 6 repeating units of alkyleneoxy group](ii) a Amino group [ e.g., a substituted amino group having 1 to 15 carbon atoms such as methylamino group, dimethylamino group, ethylamino group, methylethylamino group, diethylamino group, n-propylamino group, methyl-n-propylamino group, ethyl-n-propylamino group, isopropylamino group, isopropylmethylamino group, isopropylethylamino group, diisopropylamino group, phenylamino group, diphenylamino group, methylphenylamino group, ethylphenylamino group, n-propylphenylamino group and isopropylphenylamino group, and amino group, and the like](ii) a Halogen atom (e.g., fluorine atom, chlorine atom, bromine atom, iodine atom), hydroxyl group, etc.

Here, X is preferred^-Preferred examples of the anion represented by the above formula (1) or (2) are mentioned.

Specific examples of the first acid generator represented by the above 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, phenylmethylbenzylsulfonium tetrakis (pentafluorophenyl) borate, 4-hydroxyphenylmethylbenzylsulfonium tetrakis (pentafluorophenyl) borate, 4-methoxycarbonyloxyphenylmethylbenzsulfonium tetrakis (pentafluorophenyl) borate, 4-acetoxyphenylmethylbenzonium tetrakis (pentafluorophenyl) borate, 4-benzyloxycarbonyloxyphenylmethylbenzonium tetrakis (pentafluorophenyl) borate, phenylmethyl-2-methylbenzylsulfonium tetrakis (pentafluorophenyl) borate, phenylmethyl-2-methylbenzonium tetrakis (pentafluorophenyl) borate, and mixtures thereof, 4-Hydroxyphenylmethyl-2-methylbenzylsulfonium tetrakis (pentafluorophenyl) borate, 4-methoxycarbonyloxyphenylmethyl-2-methylbenzylsulfonium tetrakis (pentafluorophenyl) borate, 4-acetoxyphenylmethyl-2-methylbenzylsulfonium tetrakis (pentafluorophenyl) borate, 4-benzyloxycarbonyloxyphenylmethyl-2-methylbenzylsulfonium tetrakis (pentafluorophenyl) borate, phenylmethyl-1-naphthylmethylsulfinium tetrakis (pentafluorophenyl) borate, 4-hydroxyphenylmethyl-2-naphthylmethylsulfinium tetrakis (pentafluorophenyl) borate, 4-methoxycarbonyloxyphenylmethyl-1-naphthylmethylsulfinium tetrakis (pentafluorophenyl) borate, sodium salt of a compound represented by formula (I), sodium salt of a compound represented by formula (II), salt of a compound represented by formula (III) or (III), salt of a compound represented by formula (III), 4-acetoxyphenylmethyl-1-naphthylmethylthioninium tetrakis (pentafluorophenyl) borate, 4-benzyloxycarbonyloxyphenylmethyl-1-naphthylmethylthioninium tetrakis (pentafluorophenyl) borate; and an ionic compound obtained by replacing tetrakis (pentafluorophenyl) borate as a counter anion of the first acid generator with tris (pentafluoroethyl) trifluorophosphate. These first acid generators may be used alone or in combination of 2 or more.

(3) A second acid generator

The second acid generator is an ionic compound that generates an acid by irradiation with an active energy ray (for example, ultraviolet ray, visible light, electron ray, X-ray, or the like) and is capable of polymerizing the cationically polymerizable compound. The second acid generator has high thermal stability, and the curing temperature is 120 ℃ or higher, and may be, for example, 120 to 350 ℃, preferably 150 to 350 ℃, more preferably 200 to 320 ℃, and further preferably 250 to 300 ℃. The curing temperature was defined as the first acid generator, and was measured by the method described in the section of "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 ℃ or higher, and may be CF₃SO₃ ^-、C₄F₉SO₃ ^-、CH₃SO₃ ^-Iso R-SO₃ ^-(R represents an alkyl group having 1 to 6 carbon atoms or a fluoroalkyl group having 1 to 6 carbon atoms) as an anionAn anion represented by the formula (1), an anion represented by the formula (2), and SbF₆ ^-Or PF₆ ^-. Among them, in view of curability, an anion represented by the above formula (1), an anion represented by the above formula (2), or PF is preferable₆ ^-. With antimonate anions (e.g. SbF)₆ ^-) These anions are more suitable in terms of safety than others. In addition, the counter anion of the second acid generator may be the same 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 PF₆ ^-。

The counter cation constituting the second acid generator may be, for example, sulfonium, iodonium (e.g., diaryliodonium cation such as diphenyliodonium cation), diazonium (e.g., benzenediazonium cation), oxonium, ammonium, phosphonium, or the like, as long as the curing temperature of the second acid generator is 120 ℃ or higher. Among them, sulfonium and iodonium are preferable from the viewpoint of polymerization reactivity and curability, and sulfonium having good thermal stability of the adhesive is particularly preferable.

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

A preferred embodiment of the second acid generator is an ionic compound represented by the following formula (4).

[ solution 11]

[ in the formula, R¹⁴And R¹⁵Independently of one another, an alkyl group, an aralkyl group, an aryl group or an aromatic heterocyclic group, R¹⁶Represents an optionally substituted phenyl group, Y^-Is an anion represented by the above formula (1) or the above formula (2) or PF₆ ^-。]

At R¹⁴And R¹⁵In (1) as alkylExamples of the "aralkyl group", "aryl group" or "aromatic heterocyclic group" may include the aforementioned R¹¹And R¹²The alkyl group, aralkyl group, aryl group or aromatic heterocyclic group as exemplified above. R¹⁴And R¹⁵Each independently is preferably an aryl group such as a phenyl group or a naphthyl group.

R¹⁶Is a phenyl group, which may have a substituent (C). Examples of the substituent (C) include those exemplified for the substituent (B), and particularly preferred is an arylthio group or the like.

As preferred Y^-Preferred examples thereof include those represented by the above formula (1) or (2) and PF₆ ^-Etc., particularly preferably PF₆ ^-Or an anion represented by the formula (2).

The second acid generator may be a commercially available product. Examples of commercially available secondary acid generators include Kayarad PCI-220 (manufactured by Nippon chemical Co., Ltd.), Kayarad PCI-620 (manufactured by Nippon chemical Co., Ltd.), UVI-6990 (manufactured by Union carbide Corporation), Adeka Optomer SP-150 (manufactured by Adeka Co., Ltd.), Adeka Optomer SP-170 (manufactured by Adeka Co., Ltd.), CI-5102 (manufactured by Nippon Cauda Co., Ltd.), CIT-1370 (manufactured by Nippon Cauda Co., Ltd.), CIT-1682 (manufactured by Nippon Cauda Co., Ltd.), CIP-1866S (manufactured by Nippon Cauda Co., Ltd.), CIP-2048S (manufactured by Nippon Cauda Co., Ltd.), CIP-2064S (manufactured by Nippon Cauda Co., Ltd.), DPI-101 (manufactured by Nippon chemical Co., Ltd.), DPI-102 (manufactured by Nippon chemical Co., Ltd.), DPI-103 (manufactured by Nippon chemical Co., Ltd.), DPI-105 (manufactured by Nippon chemical Co., Ltd.), MPI-103 (manufactured by Nippon chemical Co., Ltd.), and the same, MPI-105 (manufactured by Afforestation corporation), BBI-101 (manufactured by Afforestation corporation), BBI-102 (manufactured by Afforestation corporation), BBI-103 (manufactured by Afforestation corporation), BBI-105 (manufactured by Afforestation corporation), TPS-101 (manufactured by Afforestation corporation), TPS-102 (manufactured by Afforestation corporation), TPS-103 (manufactured by Afforestation corporation), TPS-105 (manufactured by Afforestation corporation), MDS-103 (manufactured by Afforestation corporation), MDS-105 (manufactured by Afforestation corporation), DTS-102 (manufactured by Afforestation corporation), DTS-103 (manufactured by Afforestation corporation), PI-2074 (manufactured by Rhodia corporation), CPI-100P (manufactured by San-Apro corporation), CPI-101A (manufactured by San-Apro corporation), CPI-200K (manufactured by San-Apro corporation), CPI-210S (manufactured by San-Apro corporation), and the like.

The first acid generator and the second acid generator may be solutions 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., chain ketones such as acetone, methyl ethyl ketone, methyl isoamyl ketone, and 2-heptanone, cyclic ketones such as cyclohexanone ]; ethers [ e.g., cyclic ethers such as dioxane ]; esters [ e.g., methyl acetate, ethyl acetate, butyl acetate, etc. ]; polyhydric alcohols and derivatives thereof [ e.g., ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate, etc. ].

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

The total amount of the first acid generator and the second acid generator in the adhesive may be, for example, 0.1 to 30 parts by mass, preferably 0.2 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, still more preferably 1 to 5 parts by mass, and particularly preferably 2 to 4 parts by mass, per 100 parts by mass of the cationically polymerizable compound. When the total amount of the first acid generator and the second acid generator is equal to or greater than the lower limit value, the adhesive can be sufficiently cured, and durability and adhesiveness can be improved. On the other hand, if the total amount of the first acid generator and the second acid generator is equal to or less than the upper limit value, yellowing of the polarizing plate can be effectively suppressed when the polarizing plate is heated.

The ratio (mass ratio) of the first acid generator to the second acid generator may be, for example, 95/5 to 5/95, preferably 90/10 to 10/90, more preferably 80/20 to 20/80, still more preferably 75/25 to 25/75, particularly preferably 70/30 to 30/70, and most preferably 60/40 to 40/60. When the amount is within this range, the cationically polymerizable compound can be effectively cured, and a polarizing plate having excellent durability can be formed. From the viewpoint of durability, the second acid generator is preferably contained in the same amount as or in a larger amount than the first acid generator, and more preferably in a larger amount than the first acid generator.

The first acid generator may be used alone, or two or more different acid generators may be used in combination. In addition, only one kind of the second acid generator may be used, or two or more different kinds may be used in combination.

(4) Additive agent

The adhesive forming the adhesive layer may contain additives as necessary. Examples of the additive include an ion scavenger (for example, inorganic compounds such as powdery bismuth-based, antimony-based, magnesium-based, aluminum-based, calcium-based, titanium-based, and mixed systems thereof), an antioxidant (for example, hindered phenol-based antioxidants), a chain transfer agent, a polymerization accelerator (for example, polyhydric alcohol), a sensitizer, a sensitizing aid, a light stabilizer, an adhesion promoter, a thermoplastic resin, a filler, a flow control agent, a plasticizer, a defoaming agent, a leveling agent, a silane coupling agent, a pigment, an antistatic agent, and an ultraviolet absorber.

The adhesive layer of the present invention has high adhesion between the protective film and the polarizing plate even when left under high temperature and high humidity conditions, 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, under the condition that the jig moving speed is 300 mm/min. The peeling force (adhesive 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 storage modulus of the adhesive layer at 80 ℃ is preferably 600MPa or more. When the storage modulus is 600MPa or more, the change in the size of the polarizing plate when the polarizing plate is left in a high-temperature environment can be suppressed, and the breakage of the polarizing plate can be suppressed in a durability test in which a rapid temperature change is applied, such as a cold and thermal shock test. The storage modulus at 80 ℃ is more preferably 800MPa or more, and still more preferably 1000MPa or more.

The polarizing plate including the adhesive layer of the present invention has excellent adhesiveness and adhesiveness between the polarizer and the protective film, and can effectively suppress peeling or lifting at the interface even when a strong shrinkage stress is generated in the polarizer. Further, deterioration of optical characteristics (for example, change in transmittance of a polarizing plate) can be suppressed even under high temperature or high temperature and high humidity. Further, even when used in the form of a polarizing plate sheet, the sheet is not easily peeled off between the polarizer and the protective film due to a cutting stress at the time of cutting from a long material or a winding roll, and the processed sheet is not easily warped. Therefore, the polarizing plate of the present invention has excellent durability even under severe conditions such as high temperature and high humidity, and is therefore useful as a polarizing plate in a liquid crystal display device or the like.

[2] Polarizing plate

The polarizing plate is a film having a function of selectively transmitting linearly polarized light in one direction from natural light. Examples thereof include an iodine-based polarizing plate in which iodine is adsorbed to a polyvinyl alcohol-based resin film and oriented, a dye-based polarizing plate in which a dichroic dye is adsorbed to a polyvinyl alcohol-based resin film and oriented, and a coating-type polarizing plate in which a dichroic dye in a lyotropic liquid crystal state is coated, oriented and fixed. These polarizing plates selectively transmit linear polarized light in one direction from natural light and absorb linear polarized light in the other direction, and are therefore called absorption polarizing plates. The polarizing plate is not limited to the absorption-type polarizing plate, and may be a reflection-type polarizing plate that selectively transmits linear polarized light in one direction and reflects linear polarized light in the other direction from natural light or a scattering-type polarizing plate that scatters linear polarized light in the other direction. Among them, iodine-based polarizing plates excellent in degree of polarization and transmittance are more preferable.

As the polyvinyl alcohol resin, a polyvinyl alcohol resin obtained by saponifying a polyvinyl acetate resin can be used. As the polyvinyl acetate-based resin, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate, a copolymer of vinyl acetate and another monomer copolymerizable therewith, and the like can be mentioned. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, acrylamides having an ammonium group, and the like.

The saponification degree of the polyvinyl alcohol resin is usually about 85 to 100 mol%, and preferably 98 mol% or more. The polyvinyl alcohol resin may be modified, and for example, polyvinyl formal, polyvinyl acetal, or the like modified with aldehydes may be used. The polyvinyl alcohol resin has an average polymerization degree of usually about 1000 to 10000, preferably about 1500 to 5000. The average polymerization degree of the polyvinyl alcohol resin can be determined in accordance with JIS K6726.

A film made of such a polyvinyl alcohol resin is used as a raw material film of a polarizing plate. The method for forming the film of the polyvinyl alcohol resin is not particularly limited, and a known method can be used. The thickness of the polyvinyl alcohol-based raw material film is, for example, 150 μm or less, preferably 100 μm or less (for example, 50 μm or less).

The polarizing plate can be produced by a method including a step of uniaxially stretching a polyvinyl alcohol resin film; a step of dyeing a polyvinyl alcohol resin film with a dichroic dye to thereby adsorb the dichroic dye; a step of treating (crosslinking) the polyvinyl alcohol resin film having the dichroic dye adsorbed thereon with an aqueous boric acid solution; and a step of washing with water after the treatment with the boric acid aqueous solution.

The uniaxial stretching of the polyvinyl alcohol resin film may be performed before, simultaneously with, or after the dyeing of the dichroic dye. In the case where the uniaxial stretching is performed after dyeing, the uniaxial stretching may be performed before boric acid treatment or in boric acid treatment. In addition, uniaxial stretching may be performed in these plural stages.

In the case of uniaxial stretching, the uniaxial stretching may be performed between rolls having different peripheral speeds, or the uniaxial stretching may be performed using a heat roll. The uniaxial stretching may be dry stretching in which stretching is performed in the air, or wet stretching in which stretching is performed in a state where the polyvinyl alcohol resin film is swollen with a solvent or water. The draw 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 can be employed. As the dichroic dye, iodine or a dichroic organic dye is used. The polyvinyl alcohol resin film is preferably subjected to an immersion treatment in water before the dyeing treatment.

As the dyeing treatment with iodine, a method of immersing a polyvinyl alcohol resin film in an aqueous solution containing iodine and potassium iodide is generally employed. The iodine content in the aqueous solution may be about 0.01 to 1 part by mass per 100 parts by mass of water.

The content of potassium iodide may be about 0.5 to 20 parts by mass relative to 100 parts by mass of water. The temperature of the aqueous solution may be about 20 to 40 ℃. On the other hand, as the dyeing treatment with the dichroic organic dye, a method of immersing a polyvinyl alcohol resin film in an aqueous solution containing the dichroic organic dye is generally employed. The aqueous solution containing the dichroic organic dye may contain an inorganic salt such as sodium sulfate as a dyeing assistant. The content of the dichroic organic dye in the aqueous solution may be 1 × 10 with respect to 100 parts by mass of water^-4About 10 parts by mass. The temperature of the aqueous solution can be about 20-80 ℃.

As the boric acid treatment after dyeing with the dichroic dye, a method of immersing the dyed polyvinyl alcohol resin film in an aqueous solution containing boric acid is generally employed. In the case of using iodine as the dichroic dye, the aqueous solution containing boric acid preferably contains potassium iodide.

The amount of boric acid in the aqueous solution containing boric acid may be about 2 to 15 parts by mass relative to 100 parts by mass of water. The amount of potassium iodide in the aqueous solution may be about 0.1 to 20 parts by mass per 100 parts by mass of water. The temperature of the aqueous solution may be 50 ℃ or higher, for example, 50 to 85 ℃.

The polyvinyl alcohol resin film after the boric acid treatment is usually subjected to a water washing treatment. The water washing treatment can be performed by, for example, immersing the polyvinyl alcohol resin film subjected to the boric acid treatment in water. The temperature of water in the water washing treatment is usually about 5 to 40 ℃.

After washing with water, drying treatment was performed to obtain a polarizing plate. The drying treatment may be performed using a hot air dryer or a far infrared heater. A polarizing plate can be obtained by bonding protective films to both surfaces of the polarizer using an adhesive.

Further, as another example of a method for producing a polarizing plate, for example, the methods described in japanese patent application laid-open nos. 2000-338329 and 2012-159778 can be cited. 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 including the base film and the resin layer is stretched and then subjected to dyeing treatment, crosslinking treatment, or the like to form a polarizer layer from the resin layer. The polarizing laminated film including a base film and a polarizer layer can be produced by bonding a protective film to a polarizer layer, then peeling off and removing the base film, and further bonding another protective film to the polarizer layer exposed by peeling off the base film.

The thickness of the polarizing plate may be 40 μm or less, and preferably 30 μm or less (for example, 20 μm or less). In addition, according to the methods described in japanese patent application laid-open nos. 2000-338329 and 2012-159778, a polarizing plate of a film can be more easily manufactured, and the thickness of the polarizing plate may be, for example, 20 μm or less, and further 10 μm or less. The thickness of the polarizing plate is usually 2 μm or more. Reducing the thickness of the polarizer is advantageous for thinning the polarizing plate and thus the image display device.

[3] Protective film

The protective film may be formed of a polyolefin-based resin such as a light-transmitting (preferably optically transparent) thermoplastic resin, for example, a chain polyolefin-based resin (e.g., a polypropylene-based resin) or a cyclic polyolefin-based resin (e.g., a norbornene-based resin); 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; a polycarbonate-based resin; (meth) acrylic resins; or mixtures, copolymers, etc. thereof. The term "(meth) acrylic" means methacrylic and/or acrylic, and the term "(meth)" as used in the case of "(meth) acrylate" means the same. Among them, the first protective film 10 and the second protective film 20 (or the main component of the protective film) each preferably contain at least 1 resin selected from the group consisting of a cellulose-based resin, (meth) acrylic resin, polyolefin-based resin, polyester-based resin, and polycarbonate-based resin.

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 2 stretching directions are simultaneously stretched, or sequential biaxial stretching in which a predetermined direction is stretched and then another direction is stretched. The protective film may also be a protective film having an optical function similar to that of the retardation film. The retardation film is an optical functional film used for the purpose of compensating for a retardation by a liquid crystal cell as an image display element. For example, a retardation film to which an arbitrary retardation value is given can be produced by stretching a film made of the above thermoplastic resin (uniaxial stretching, biaxial stretching, or the like), or forming a liquid crystal layer or the like on the film.

Examples of the chain polyolefin resin include homopolymers of chain olefins such as polyethylene resins and polypropylene resins, and copolymers of 2 or more kinds of chain olefins.

The cyclic polyolefin resin is a general name of a resin containing, as a polymerization unit, a cyclic olefin typified by norbornene, tetracyclododecene (also known as dimethyloctahydronaphthalene) or a derivative thereof. Specific examples of the cyclic polyolefin resin include ring-opened (co) polymers of cyclic olefins and hydrogenated products thereof, addition polymers of cyclic olefins, copolymers of cyclic olefins with linear olefins such as ethylene and propylene or aromatic compounds having a vinyl group, and modified (co) polymers obtained by modifying these with unsaturated carboxylic acids or derivatives thereof. Among them, norbornene-based resins using norbornene-based monomers such as norbornene or polycyclic norbornene-based monomers as cyclic olefins are preferably used.

The cellulose resin is preferably a cellulose ester resin obtained by esterifying at least a part of hydroxyl groups in cellulose with acetic acid, and may be a mixed ester in which a part of hydroxyl groups is esterified with acetic acid and a part of hydroxyl groups is esterified with another acid. The cellulose ester resin is preferably an acetyl cellulose resin. Specific examples of the acetyl cellulose resin include triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, and cellulose acetate butyrate.

The polyester resin is a resin having an ester bond other than the cellulose ester resin, and is generally a resin formed from a polycondensation product of a polycarboxylic acid or a derivative thereof and a polyhydric alcohol. Specific examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polypropylene terephthalate, polypropylene naphthalate, polycyclohexanediphthalate, polycyclohexanedinaphthalate and the like. Among them, polyethylene terephthalate is preferably used from the viewpoint of mechanical properties, solvent resistance, scratch resistance, cost, and the like. Polyethylene terephthalate is a resin composed of ethylene terephthalate in which 80 mol% or more of the repeating units are contained, and may contain a constituent unit derived from another copolymerizable component.

Examples of the other copolymerizable component include a dicarboxylic acid component and a diol component. Examples of the dicarboxylic acid component include isophthalic acid, 4 '-dicarboxybiphenyl, 4' -dicarboxybenzophenone, bis (4-carboxyphenyl) ethane, adipic acid, sebacic acid, sodium 5-sulfoisophthalate, and 1, 4-dicarboxycyclohexane. Examples of the diol component include propylene glycol, butylene glycol, neopentyl glycol, diethylene glycol, cyclohexanediol, ethylene oxide adducts of bisphenol a, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like. The dicarboxylic acid component or the diol component may be used in combination of 2 or more, as required. In addition, can also be p-hydroxy benzoic acid, p-hydroxy ethoxy benzoic acid and hydroxy carboxylic acid and the two carboxylic acid component or glycol component together. As the other copolymerizable component, a dicarboxylic acid component and/or diol component having an amide bond, a urethane bond, an ether bond, a carbonate bond, or the like may be used in a small amount.

The polycarbonate-series resin is a polyester formed from carbonic acid and a diol or bisphenol. Among them, from the viewpoint of heat resistance, weather resistance and acid resistance, an aromatic polycarbonate having diphenylalkane in the molecular chain is preferably used. Examples of the polycarbonate include polycarbonates derived from bisphenols such as 2, 2-bis (4-hydroxyphenyl) propane (also referred to as bisphenol a), 2-bis (4-hydroxyphenyl) butane, 1-bis (4-hydroxyphenyl) cyclohexane, 1-bis (4-hydroxyphenyl) isobutane, and 1, 1-bis (4-hydroxyphenyl) ethane.

The (meth) acrylic resin may be a polymer (containing 50 mass% or more) containing a methacrylic acid ester as a main monomer, and is preferably a copolymer obtained by copolymerizing a small amount of another copolymerization component. The (meth) acrylic resin is more preferably a copolymer of methyl methacrylate and methyl acrylate, and may be further copolymerized with a third monofunctional monomer.

As the third monofunctional monomer, for example: methacrylates other than methyl methacrylate 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, and 2-hydroxyethyl acrylate; hydroxyalkyl acrylates such as methyl 2- (hydroxymethyl) acrylate, methyl 2- (1-hydroxyethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate and butyl 2- (hydroxymethyl) acrylate; unsaturated acids such as methacrylic acid and acrylic acid; halogenated styrenes such as chlorostyrene and bromostyrene; substituted styrenes such as vinyl toluene and α -methylstyrene; unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated acid anhydrides such as maleic anhydride and citraconic anhydride; unsaturated imides such as phenylmaleimide and cyclohexylmaleimide. The third monofunctional monomer may be used alone or in combination of 2 or more.

The polyfunctional monomer may be further copolymerized with a (meth) acrylic resin. 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, nonaethylene glycol di (meth) acrylate, tetradecene glycol di (meth) acrylate, and the like, in which both terminal hydroxyl groups of ethylene glycol or an oligomer thereof are esterified with (meth) acrylic acid; a substance obtained by esterifying both terminal hydroxyl groups of propylene glycol or an oligomer thereof with (meth) acrylic acid; a 2-membered alcohol having a hydroxyl group esterified with (meth) acrylic acid, such as neopentyl glycol di (meth) acrylate, hexanediol di (meth) acrylate, or butanediol di (meth) acrylate; esterified with (meth) acrylic acid at both terminal hydroxyl groups of bisphenol a, an alkylene oxide adduct of bisphenol a, or a halogen-substituted product thereof; esterification products of polyhydric alcohols such as trimethylolpropane and pentaerythritol with (meth) acrylic acid, and products obtained by ring-opening addition of terminal hydroxyl groups thereof to epoxy groups of glycidyl (meth) acrylate; a compound obtained by ring-opening addition of an epoxy group of glycidyl (meth) acrylate to a dibasic acid such as succinic acid, adipic acid, terephthalic acid, phthalic acid, a halogen-substituted compound thereof, or an alkylene oxide adduct thereof; aryl (meth) acrylate; and aromatic divinyl compounds such as divinylbenzene. Among them, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate and neopentyl glycol dimethacrylate are preferably used.

The (meth) acrylic resin may be a (meth) acrylic resin modified by further performing a reaction between functional groups of the copolymer. Examples of the reaction include an in-polymer chain demethoxylation condensation reaction of a methyl ester group of methyl acrylate and a hydroxyl group of methyl 2- (hydroxymethyl) acrylate, and an in-polymer chain dehydration condensation reaction of a carboxyl group of acrylic acid and a hydroxyl group of methyl 2- (hydroxymethyl) acrylate.

The glass transition temperature of the (meth) acrylic resin is preferably 80 to 160 ℃. The glass transition temperature can be controlled by adjusting the polymerization ratio of the methacrylate monomer and the acrylate monomer, the carbon chain length of each ester group, the kind of the functional group having each ester group, and the polymerization ratio of the polyfunctional monomer to the total monomers.

In addition, as a means for increasing the glass transition temperature of the (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, or a lactone structure. Specific examples thereof include a cyclic acid anhydride structure such as a glutaric anhydride structure and a succinic anhydride structure, a cyclic imide structure such as a glutarimide structure and a succinimide structure, and a lactone ring structure 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 a method of copolymerizing monomers having a cyclic structure such as maleic anhydride and maleimide; a method of introducing a cyclic acid anhydride structure by dehydration/demethanol condensation reaction after polymerization; a method of introducing a cyclic imide structure by reacting an amino compound, and the like. The resin (polymer) having a lactone ring structure can be obtained by preparing a polymer having a hydroxyl group and an ester group in a polymer chain, and then heating the polymer in the presence of a catalyst such as an organic phosphorus compound if necessary to cyclize-condense the hydroxyl group and the ester group in the obtained polymer to form a lactone ring structure.

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

The (meth) acrylic resin may contain acrylic rubber particles as an impact modifier from the viewpoints of film formability of the resulting film, impact resistance of the film, and the like. The acrylic rubber particles are particles containing an elastic polymer mainly composed of an acrylic ester as an essential component, and include acrylic rubber particles having a single-layer structure substantially composed of only the elastic polymer and acrylic rubber particles having a multi-layer structure containing the elastic polymer as 1 layer. Examples of the elastic polymer include a crosslinked elastic copolymer containing an alkyl acrylate as a main component and copolymerized with another copolymerizable vinyl monomer and a crosslinkable monomer. Examples of the alkyl acrylate which is the main component of the elastic polymer include alkyl acrylates having an alkyl group of about 1 to 8 carbon atoms such as methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate, and alkyl acrylates having an alkyl group of 4 or more carbon atoms are preferably used. Examples of the other vinyl monomer copolymerizable with the alkyl acrylate include compounds having 1 polymerizable carbon-carbon double bond in the molecule, more specifically, methacrylic acid esters such as methyl methacrylate, aromatic vinyl compounds such as styrene, and vinyl cyanide compounds such as acrylonitrile. Examples of the crosslinkable monomer include crosslinkable compounds having at least 2 polymerizable carbon-carbon double bonds in the molecule, and more specifically, include (meth) acrylates of polyhydric alcohols such as ethylene glycol di (meth) acrylate and butanediol di (meth) acrylate, alkenyl esters of (meth) acrylic acid such as allyl (meth) acrylate, and divinylbenzene.

The protective film may be formed of a laminate of a film made of a (meth) acrylic resin containing no rubber particles and a film made of a (meth) acrylic resin containing rubber particles. In addition, a protective film may be formed by forming a (meth) acrylic resin layer on one or both surfaces of a retardation-developing layer made of a resin different from the (meth) acrylic resin to develop a retardation.

The protective film may contain an ultraviolet absorber. When the polarizing plate is applied to an image display device such as a liquid crystal display device, deterioration of the image display element due to ultraviolet rays can be suppressed by disposing a protective film containing an ultraviolet absorber on the observation side of the image display element (for example, a liquid crystal cell). Examples of the ultraviolet absorber include salicylate-based compounds, benzophenone-based compounds, benzotriazole-based compounds, cyanoacrylate-based compounds, and nickel complex salt-based compounds.

In fig. 1, the first protection film 10 and the second protection film 20 may be films made of the same resin or may be films made of different resins. The first protective film 10 and the second protective film 20 may be the same or different in thickness, presence or absence of an additive, type of an additive, retardation characteristics, and the like.

The first protective film 10 and/or the second protective film 20 may have a surface treatment layer (coating layer) such as a hard coat layer, an antiglare layer, an antireflection layer, a light diffusion layer, an antistatic layer, an antifouling layer, and a conductive layer on the outer surface (surface on the opposite side of the polarizing plate 30).

The thicknesses of the first protective film 10 and the second protective film 20 are generally 5 to 200 μm, preferably 10 to 120 μm, and more preferably 10 to 85 μm, respectively. Reducing the thickness of the protective film is advantageous for thinning the polarizing plate and thus the image display device.

< method for producing polarizing plate >

The polarizing plate of the present invention is manufactured by a method including the steps of,

(a) coating an adhesive on the polarizing plate and/or the protective film;

(b) a step of laminating a polarizing plate and a protective film;

(c) irradiating the laminate obtained in the step (b) with an active energy ray; and

(d) then, the laminate is heated.

For example, the polarizing plate shown in fig. 1 can be formed by laminating and bonding a first protective film 10 on one surface of a polarizer 30 via a first adhesive layer 15, and laminating and bonding a second protective film 20 on the other surface of the polarizer 30 via a second adhesive 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 one by one in stages, or double-sided protective films may be laminated and bonded one by one.

Specifically, an adhesive is applied to the bonding surface of the polarizing plate 30 and/or the bonding surface of the protective film (step (a)), and the films are stacked via the coating layer of the adhesive and pressed from above and below using, for example, a bonding roller to bond and laminate the films (step (b)). Next, the adhesive layer is cured by irradiation with an active energy ray (step (c), referred to as "active energy ray irradiation step"), and then heating (step (d), referred to as "heating step") to form the polarizing plate. Before the coating layer of the adhesive is formed, one or both of the surfaces to be bonded of the polarizing plate 30 and the protective film may be subjected to an easy adhesion treatment such as a saponification treatment, a corona discharge treatment, a plasma treatment, a flame treatment, a primer treatment, or an anchor coating treatment.

In the method for producing a polarizing plate of the present invention, the second acid generator mainly functions to cure the cationically polymerizable compound in the active energy irradiation step (c). In the heating step (d), the first acid generator mainly acts to further cure the cationically polymerizable compound which is not cured or is insufficiently cured in the active energy irradiation step. As described above, in the present invention, since the adhesive is formed by combining the predetermined cationically polymerizable compound and the predetermined second acid generator, an adhesive layer having high adhesiveness and the like can be formed by the active energy irradiation step, and further, in the heating step, the first acid generator having the counter anion having high acidity of the conjugate acid acts to accelerate curing, and thus, a polarizing plate having excellent peeling resistance, curl resistance, deterioration resistance (moisture and heat resistance) and the like can be formed.

In the steps (a) and (b), various coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used to form the coating layer of the adhesive. Further, a method of casting the adhesive between the polarizing plate 30 and the protective film while continuously supplying the polarizing plate and the protective film so that the bonding surfaces of the both are on the inner side may be adopted.

From the viewpoint of coatability, it is preferable to reduce the viscosity of the adhesive for forming the first adhesive layer 15 and the second adhesive layer 25. Specifically, the viscosity at 25 ℃ is preferably 1000 mPas or less, more preferably 500 mPas or less, and still more preferably 100 mPas or less. The adhesive may be a solvent-free type, and contains an organic solvent in order to adjust the viscosity suitable for the application method used.

In the step (c), the light source of the active energy ray may be any light source that generates ultraviolet rays, electron rays, X-rays, or the like, and preferably ultraviolet rays. The ultraviolet light source is preferably a light source having an emission distribution at a wavelength of 400nm or less, and examples thereof include 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, and a metal halide lamp.

The irradiation intensity of the active energy ray with respect to the adhesive layer is determined according to the adhesive, and it is preferable that the irradiation intensity in the wavelength region effective for activation of the second acid generator is 0.1 to 1000mW/cm². If the light irradiation intensity is too low, the reaction time becomes too long, while if the light irradiation intensity is too high, yellowing of the adhesive layer, deterioration of the polarizing plate 30, and surface defects of the protective film may occur due to heat radiated from the lamp and heat generated during polymerization of the adhesive. The irradiation time of the adhesive is also controlled according to the adhesive, and the cumulative light quantity expressed as the product of the irradiation intensity and the irradiation time is, for example, 10 to 3000mJ/cm²Preferably 10 to 1000mJ/cm²More preferably 50 to 500mJ/cm²More preferably 100 to 300mJ/cm²The mode of (2) is set. If the cumulative light amount is equal to or less than the upper limit, the light irradiation time is not excessively long, which is advantageous for improving productivity, and if the cumulative light amount is equal to or more than the lower limit, the acid generator (particularly, the second acid generator) can efficiently generate acid, and the adhesive layer can be sufficiently cured.

The active energy ray may be irradiated from either one of the protective film or the polarizing film, and is usually irradiated from the film side having high transmittance in the vicinity of the absorption wavelength of the second acid generator.

Since the first acid generator is used in combination in the present invention, even when the active energy ray is irradiated through a protective film having a low transmittance, such as a transmittance of 85% or less (preferably 70% or less) at 320nm and a transmittance of 50% or less (preferably 10% or less) at 300nm, the first acid generator functions by heating, so that the curing of the adhesive agent is sufficiently performed, and the durability of the polarizing plate is improved. The present invention also has improved durability when irradiated with active energy rays through a protective film having low transmittance, such as a transmittance of 85% or less (preferably 70% or less) at 320nm, a transmittance of 50% or less (preferably 10% or less) at 300nm, and a transmittance of 85% or less at 350 nm.

In the step (d), at least the adhesive layer may be heated, and for example, a laminate of the protective films 10 and 20, the adhesive layers 15 and 25, and the polarizing plate 30 may be heated. Examples of the heating method include a method in which the long protective film or the laminate is sequentially passed through a device that emits radiant heat such as an infrared heater, and a method in which a gas heated by a blower or the like is blown to the long protective film or the laminate. The heating temperature may be appropriately selected depending on the curing temperature of the first acid generator. Specifically, the temperature at which the first acid generator easily generates an acid may be, for example, a curing temperature ± 30 ℃, preferably a curing temperature ± 20 ℃, and more preferably a curing temperature ± 10 ℃. When the amount is within this range, the cationically polymerizable compound which is not cured or is insufficiently cured in the active energy irradiation step can be effectively cured, and therefore, the adhesiveness between the polarizing plate and the protective film can be improved. The heating temperature may be, for example, 50 to 150 ℃, preferably 70 to 120 ℃, more preferably 80 to 100 ℃, and particularly preferably 85 to 95 ℃. Within this range, thermal degradation of the polarizing plate can be suppressed, and the cationic polymerizable compound is advantageous also in view of polymerizability and curability.

In addition, in the present invention, since a predetermined first acid generator is used, the curing rate is high. Therefore, the heating time in the heating step may be, for example, 1 second to 1 hour, preferably 10 seconds to 30 minutes (e.g., 20 seconds to 10 minutes), more preferably 30 seconds to 5 minutes, and particularly preferably 50 seconds to 2 minutes.

The timing of laminating the protective film on the polarizing plate 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 one protective film 10 is laminated, the coating layer may be cured, and then another protective film 20 may be laminated to cure the coating layer. Alternatively, after the protective films are laminated one after another or simultaneously, the coating layers on both surfaces may be cured simultaneously. In the step (c), the irradiation with the active energy ray may be performed from either protective film side.

The thickness of the cured adhesive layer (for example, the thickness of the first adhesive layer 15 and the second adhesive layer 25) is usually 20 μm or less, preferably 10 μm or less, more preferably 5 μm or less, and 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. The thicknesses of the first adhesive layer 15 and the second adhesive layer 25 may be the same or different.

< other structural elements of polarizing plate >

(1) Optical functional film

The polarizing plate may be provided with other optical functional films for imparting desired optical functions, other than the polarizer 30, 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 may also serve as a retardation film, but a retardation film separate from the protective film may be laminated. In the latter case, the retardation film may be laminated on the outer surface of the first protection film 10 and/or the second protection film 20 via an adhesive layer or an adhesive layer.

Specific examples of the retardation film include a birefringent film formed from a stretched film of a light-transmitting thermoplastic resin, a film in which a discotic liquid crystal or a nematic liquid crystal is aligned and fixed, and a film in which the liquid crystal layer is formed on a substrate film. The base film is usually a thermoplastic resin film, and a cellulose ester resin such as triacetyl cellulose is preferably used as the thermoplastic resin.

As the thermoplastic resin forming the birefringent film, the thermoplastic resins described for the protective film can be used. For example, when a cellulose ester resin is used as an example, a birefringent film can be obtained by a method of forming a film by adding a compound having a retardation adjusting function to a cellulose ester resin, a method of applying a compound having a retardation adjusting function to the surface of a cellulose ester resin film, or a method of uniaxially or biaxially stretching a cellulose ester resin. As the thermoplastic resin forming the birefringent film, other thermoplastic resins such as a polyvinyl alcohol-based resin, a polystyrene-based resin, a polyarylate-based resin, and a polyamide-based resin may be used.

The retardation film may be used in combination with 2 or more sheets for the purpose of controlling optical characteristics such as a broad band. In addition, not only the film having optical anisotropy, but also a substantially optically isotropic zero retardation film may be used as the retardation film. The zero retardation film refers to the in-plane phase difference value R_eAnd a phase difference value R in the thickness direction_thAll the films are-15 to 15 nm. In-plane retardation value R as used herein_eAnd a phase difference value R in the thickness direction_thIs the value at a wavelength of 590 nm.

In-plane phase difference value R_eAnd a phase difference value R in the thickness direction_thAre defined by the following formulae, respectively.

R_e＝(n_x-n_y)×d

R_th＝〔(n_x+n_y)/2-n_z〕×d

In the formula, n_xIs a refractive index in a slow axis direction (x axis direction) in a film plane, n_yIs a refractive index in a fast axis direction (a y axis direction orthogonal to an x axis in a plane) in a film plane, n_zThe refractive index in the film thickness direction (z-axis direction perpendicular to the film surface) and d is the film thickness.

The zero-retardation film may be formed using a thermoplastic resin described for the protective film or the birefringent film, and may be formed using, for example, a resin film made of a cellulose ester resin, a polyolefin resin such as a chain polyolefin resin or a cyclic polyolefin resin, or a polyester resin such as polyethylene terephthalate. Among them, cellulose ester resins and polyolefin resins are preferably used because the retardation value is easily controlled and easily obtained.

Examples of other optical functional films (optical members) that can be included in the polarizing plate include a light-collecting plate, a brightness enhancement film, a reflective layer (reflective film), a semi-transmissive reflective layer (semi-transmissive reflective film), a light-diffusing layer (light-diffusing film), and the like. These are generally provided when the polarizing plate is a polarizing plate disposed on the back side (backlight side) of the liquid crystal cell.

The condensing plate is used for the purpose of optical path control, and may be a prism array sheet, a lens array sheet, a sheet with dots (dots) attached thereto, or the like.

A brightness enhancement film is used for the purpose of improving the brightness of a liquid crystal display device to which a polarizing plate is applied. Specifically, there are a reflective polarizing separator in which a plurality of films having different refractive index anisotropy are laminated and designed to have an anisotropic reflectance, a circularly polarizing separator in which an alignment film of a cholesteric liquid crystal polymer or an alignment liquid crystal layer thereof is supported on a base film, and the like.

In order to make the polarizing plate a reflective, semi-transmissive, or diffusive optical member, a reflective layer, a semi-transmissive reflective layer, and a light diffusive layer are provided, respectively. A reflective polarizing plate is used for a liquid crystal display device of a type that reflects incident light from an observation side to perform display, and a light source such as a backlight can be omitted, so that the liquid crystal display device can be easily thinned. A transflective polarizing plate is used in a liquid crystal display device which is reflective in a bright place and displays a liquid crystal in a dark place by light from a backlight. In addition, the diffusion type polarizing plate is used for a liquid crystal display device in which light diffusion is provided to suppress display defects such as moire (moire). The reflective layer, the semi-transmissive reflective layer, and the light diffusion layer can be formed by a known method.

(2) Adhesive layer

The polarizing plate of the present invention may include an adhesive layer for bonding the polarizing plate to an image display element such as a liquid crystal cell or other optical members. The adhesive layer may be laminated on the outer surface of the protective film.

As the adhesive used in the adhesive layer, an adhesive using a base polymer such as a (meth) acrylic resin, a silicone resin, a polyester resin, a polyurethane resin, or a polyether resin can be used. Among them, a (meth) acrylic adhesive is preferably used from the viewpoint of transparency, adhesive force, reliability, weather resistance, heat resistance, reworkability, and the like. The (meth) acrylic adhesive is useful as a base polymer which is a mixture of an alkyl (meth) acrylate having an alkyl group having 20 or less carbon atoms such as a methyl group, an ethyl group, or a butyl group and a functional group-containing (meth) acrylic monomer such as (meth) acrylic acid or hydroxyethyl (meth) acrylate, and which has a weight average molecular weight of 10 ten thousand or more, so that the glass transition temperature is preferably 25 ℃ or less, more preferably 0 ℃ or less.

The adhesive layer can be formed on the polarizing plate by, for example, preparing a 10 to 40 mass% solution by dissolving or dispersing an adhesive composition in an organic solvent such as toluene or ethyl acetate, and directly applying the solution to the surface of the polarizing plate to form the adhesive layer; a method of forming a sheet-like pressure-sensitive adhesive layer on the release film subjected to the release treatment in advance and moving and attaching the sheet-like pressure-sensitive adhesive layer to the target surface of the polarizing plate. The thickness of the pressure-sensitive adhesive layer is determined by the adhesive strength, and is preferably in the range of about 1 to 50 μm, and more preferably 2 to 40 μm.

The polarizing plate may include the above-described separation film. The separator may be formed of a polyethylene resin such as polyethylene, a polypropylene resin such as polypropylene, a polyester resin such as polyethylene terephthalate, or the like. Among them, stretched films of polyethylene terephthalate are preferable.

The pressure-sensitive adhesive layer may contain, as necessary, fillers including glass fibers, glass beads, resin beads, metal powder, and other inorganic powders, pigments, colorants, antioxidants, ultraviolet absorbers, antistatic agents, and the like.

Examples of the antistatic agent include ionic compounds, conductive fine particles, conductive polymers, and the like, and ionic compounds are preferably used. The cationic component constituting the ionic compound may be an inorganic anion or an organic anion, and is preferably an organic cation from the viewpoint of compatibility with the (meth) acrylic resin. Examples of the organic cation include a pyridinium cation, an imidazolium cation, an ammonium cation, a sulfonium cation, and a phosphonium cation. On the other hand, the anion component constituting the ionic compound may be an inorganic anion or an organic anion to impart a resistanceIn view of the ionic compound having excellent electrostatic properties, an anionic component containing a fluorine atom is preferred. Examples of the anion component containing a fluorine atom include hexafluorophosphate anion [ (PF)₆ ^-)]Bis (trifluoromethanesulfonyl) imide anion [ (CF)₃SO₂)₂N^-]Anion, bis (fluorosulfonyl) imide anion [ (FSO)₂)₂N^-]Anions and the like.

(3) Protective film

The polarizing plate of the present invention may include a protective film for temporarily protecting the surface thereof (protective film surface). For example, after a polarizing plate is attached to an image display element or other optical member, the protective film is peeled and removed together with the adhesive layer included therein.

The protective film is composed of a base film and an adhesive layer laminated on the base film.

The above description is cited for the adhesive layer. The resin constituting the base film may be, for example, a polyethylene-based resin such as polyethylene, a polypropylene-based resin such as polypropylene, a polyester-based resin such as polyethylene terephthalate or polyethylene naphthalate, a thermoplastic resin such as a polycarbonate-based resin. Polyester resins such as polyethylene terephthalate are preferred.

Examples

The present invention will be described more specifically below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following examples, the following materials are used as the cationically polymerizable compound, the first acid generator, and the second acid generator constituting the adhesive.

(cationic polymerizable Compound)

< production example 1>

The cationically polymerizable compound was prepared by mixing the following compound (a-1), compound (a-2) and compound (a-3) in a mass ratio of (a-1) to (a-2) to (a-3) of 70: 25: 5. The obtained cationically polymerizable compound was referred to as "cationically polymerizable compound a".

Compound (A-1): 3, 4-Epoxycyclohexanecarboxylic acid-3 ', 4' -epoxycyclohexylmethyl ester (product name "CEL 2021P" manufactured by Dailuo Co., Ltd., epoxy equivalent: 126 to 145 g/equivalent)

Compound (A-2): neopentyl glycol diglycidyl ether (trade name "EX-211L" manufactured by Nagase ChemteX, Ltd., epoxy equivalent: 108 to 130 g/eq),

Compound (A-3): 3-Ethyl-3 { [ (3-ethyloxetan-3-yl) methoxy ] methyl } oxetane (trade name "OXT-221", manufactured by Toyo Seisakusho Co., Ltd.)

< production example 2>

The cation polymerizable compound is obtained by reacting the following compound (A-1) and compound (A-2) in the following ratio (A-1): (a-2) ═ 40: 60 by mass ratio. The obtained cationically polymerizable compound was referred to as "cationically polymerizable compound B".

Compound (A-1): 3, 4-Epoxycyclohexanecarboxylic acid-3 ', 4' -epoxycyclohexylmethyl ester (product name "CEL 2021P" manufactured by Dailuo Co., Ltd., epoxy equivalent: 126 to 145 g/equivalent)

Compound (A-2): neopentyl glycol diglycidyl ether (trade name "EX-211L" manufactured by Nagase ChemteX, Ltd., epoxy equivalent: 108 to 130 g/equivalent)

(first acid Generator)

Compound (B-1): an acid generator having the following structure was used. Curing temperature: at 100 ℃.

[ solution 12]

Compound (B-3): an acid generator having the following structure was used. Curing temperature: 113 ℃.

[ solution 13]

(second acid generator)

Compound (B-2): an acid generator having the following structure (San-Apro Co., Ltd., trade name "CPI-100P") was used. Curing temperature: 272 ℃.

[ solution 14]

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

[ solution 15]

(measurement of curing temperature of acid Generator)

The curing temperature of the acid generator was measured by the following method.

To 100 parts by mass of the compound (A-1), 1 part by mass (solid content) of the first acid generator (B-1) or the second acid generator (B-2) was added to prepare a curable resin composition, and 10mg of the curable resin composition was collected and placed in an aluminum cap type container, and the container was pressed and sealed to prepare a sample for measurement. Subsequently, the vessel containing the above-mentioned measurement sample was set in a Differential Scanning Calorimeter (DSC) [ SII Nano Technology, EXSTAR-6000DSC6220 "], and the temperature was raised from 30 ℃ to 300 ℃ at a rate of 10 ℃/min while purging with nitrogen gas. From the obtained DSC curve, the temperature at which the generated heat reaches the maximum value was set as the curing temperature. Incidentally, the DSC curve obtained by collecting 10mg of "CEL 2021P" alone and performing the same operation as described above showed no endothermic or exothermic reaction at 30 to 200 ℃. Further, B-2 was a 50% solution, and the amount of the solid content was 1 part by mass based on 100 parts by mass of the compound (A-1).

The curing temperature of the first acid generator (B-3) and the second acid generator (B-4) was also measured in the same manner as described above. The second acid generator (B-4) was added as a 50% propylene carbonate solution, and the amount of the solid content was 1 part by mass based on 100 parts by mass of the compound (A-1).

(1) Preparation of the adhesive

The above cationic polymerizable compound, first acid generator and second acid generator were measured in a 20mL spiral tube at the mixing ratios described in table 1 (the numerical values in table 1 represent parts by mass), and mixed and defoamed to prepare liquid ultraviolet-curable adhesives, respectively. The second acid generator (B-2) and the second acid generator (B-4) were mixed as a 50% propylene carbonate solution, and the amounts of solid components thereof are shown in table 1.

(2) Fabrication of polarizing plates

< examples 1 and 2>

One surface of an acetyl cellulose resin film (product name "koniacac KC8UX2 MW" manufactured by Konica Minolta Opto corporation, transmittance at 300nm, transmittance at 320nm, and transmittance at 350 nm) containing an ultraviolet absorber and having a thickness of 80 μm was subjected to corona discharge treatment, and the adhesive described in table 1 was applied to the corona discharge treated surface by using a bar coater so that the cured thickness became about 2.5 μm. Then, a polyvinyl alcohol (PVA) -iodine polarizing film (polarizing plate) having a thickness of 25 μm was laminated on the coated surface. Next, one surface of a retardation film (product name "ZEONOR" manufactured by japan ZEON corporation, transmittance at 300nm of 90%, transmittance at 320nm of 90%, and transmittance at 350nm of 91%) formed of a cyclic polyolefin resin (norbornene resin) and having a thickness of 50 μm was subjected to corona discharge treatment, and the adhesive described in table 1 was similarly applied to the corona discharge treated surface by using a bar coater so that the cured thickness became about 2.5 μm. The polarizing film with the acetyl cellulose resin film prepared above was superimposed on the coating surface on the polarizing film side, and was pressed and bonded using a bonding roller to obtain a laminate. The laminate was irradiated with ultraviolet rays with a conveyer belt (lamp "D Bulb" manufactured by Fusion UV Systems) so that the cumulative light amount became 200mJ/cm²(UVB) was irradiated with ultraviolet light from the side of the cyclic polyolefin resin film, and then heated at 90 ℃ for 1 minute to cure the double-sided adhesive layer, thereby producing a polarizing plate.

< comparative example 1>

A polarizing plate was produced in the same manner as in example 1, except that the laminated body was heated at 90 ℃ for 5 minutes without being irradiated with ultraviolet rays. The adhesive was heated at 90 ℃ for 1 minute for 5 minutes because the adhesive was not cured.

< examples 3 to 6>

Polarizing plates were produced in the same manner as in example 1, except that the adhesives were changed to the adhesives listed in table 1, respectively.

< example 7>

A polarizing plate was produced in the same manner as in example 1, except that the adhesive was changed to the adhesive described in table 1, and the polarizing plate was heated at 100 ℃ for 1 minute after irradiation with ultraviolet light.

< example 8>

A polarizing plate was produced in the same manner as in example 1, except that the adhesive was changed to the adhesive described 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 described in table 1, and the polarizing plate was heated at 100 ℃ for 1 minute after irradiation with ultraviolet light.

< example 10>

A polarizing plate was produced in the same manner as in example 1, except that the adhesive was changed to the adhesive described in table 1.

< example 11>

One surface of an acetyl cellulose resin film (product name "koniacac KC8UX2 MW" manufactured by Konica Minolta Opto) having a thickness of 80 μm and containing an ultraviolet absorber was subjected to corona discharge treatment, and the adhesive described in table 1 was applied to the corona discharge treated surface by a bar coater so that the cured thickness became about 2.5 μm. Then, a polyvinyl alcohol (PVA) -iodine polarizing film (polarizing plate) having a thickness of 25 μm was laminated on the coated surface. Then, one surface of a 25 μm thick film (transmittance at 300nm of 0%, transmittance at 320nm of 68%, and transmittance at 350nm of 83%) made of a polyester resin (polyethylene terephthalate) was subjected to corona discharge treatment, and the cured film was coated with a bar coater so that the thickness thereof became about 2.5 μmThe corona discharge treated surface was coated with the adhesive shown in table 1 in the same manner. The polarizing film with the acetyl cellulose resin film prepared above was superimposed on the coating surface on the polarizing film side, and was pressed and bonded using a bonding roller to obtain a laminate. The laminate was irradiated with ultraviolet rays with a conveyer belt (lamp "D Bulb" manufactured by Fusion UV Systems) so that the cumulative light amount became 400mJ/cm²(UVB) method a polarizing plate was produced by irradiating the polyester resin film side with ultraviolet rays, followed by heating at 90 ℃ for 1 minute to cure the double-sided adhesive layer.

< example 12>

One surface of an acetyl cellulose resin film (product name "koniacac KC8UX2 MW" manufactured by Konica Minolta Opto) having a thickness of 80 μm and containing an ultraviolet absorber was subjected to corona discharge treatment, and the adhesive described in table 1 was applied to the corona discharge treated surface by a bar coater so that the cured thickness became about 2.5 μm. Then, a polyvinyl alcohol (PVA) -iodine polarizing film (polarizing plate) having a thickness of 25 μm was laminated on the coated surface. Next, a film of 40 μm thickness formed of an acetyl cellulose-based resin [ trade name: "KC 4 CR-1", manufactured by Konica Minolta Opto, having a transmittance at 300nm of 49%, a transmittance at 320nm of 90%, and a transmittance at 350nm of 90% ", was subjected to a corona discharge treatment, and the adhesive described in Table 1 was applied to the corona discharge treated surface in the same manner using a bar coater so that the thickness after curing became about 2.5. mu.m. The polarizing film with the acetyl cellulose resin film prepared above was superimposed on the coating surface on the polarizing film side, and was pressed and bonded using a bonding roller to obtain a laminate. The laminate was irradiated with ultraviolet rays with a conveyer belt (lamp "D Bulb" manufactured by Fusion UV Systems) so that the cumulative light amount became 200mJ/cm²(UVB) method, the polarizing plate was produced by irradiating the acetyl cellulose resin film (film having a thickness of 40 μm) with ultraviolet rays, followed by heating at 90 ℃ for 1 minute to cure the double-sided adhesive layer.

(3) Evaluation of appearance of polarizing plate

A single piece having a size of 8cm × 8cm was cut out from the polarizing plate produced in (2) above. The sheet was left to stand overnight at a temperature of 23 ℃ and a relative humidity of 60%, and then the amount of curl of the sheet was measured. The curl amount is as follows: the sheet body in which the bending occurred was placed on a horizontal table in a downwardly convex manner, and the average of 4-point values obtained by measuring the height from the table to 4 corners of the sheet body with a straight edge, respectively. Based on the obtained curl amount, the determination was made according to the following criteria. The results are shown in Table 2.

< evaluation standards for appearance of polarizing plate >

4: the curl amount is less than 8 nm.

3: the curl amount is 8mm or more and less than 13 mm.

2: the curl amount is 13mm or more.

1: the polarizing plate is rolled into a cylindrical shape or floats between the protective film and the polarizer.

(4) Evaluation of peeling force (adhesive force)

The surface of the protective film made of triacetyl cellulose resin of the polarizing plate thus obtained was subjected to corona discharge treatment, and a commercially available (meth) acrylic pressure-sensitive adhesive sheet having a thickness of 25 μm was then bonded to the corona discharge treated surface to prepare a polarizing plate with a pressure-sensitive adhesive layer. A test piece having a width of 25mm and a length of about 200mm was cut out from the resulting polarizing plate with an adhesive layer, and the adhesive layer surface was bonded to soda glass. The sample was stored at 80 ℃ and 90% relative humidity for 24 hours, and then stored at 23 ℃ and 55% relative humidity overnight. Then, the polarizing film and the protective film were peeled from each other by 30mm from the ends in the longitudinal direction by cutting the edge of a cutter, and the peeled portion was held by a jig of a universal tensile tester (product name "AG-1" manufactured by Shimadzu corporation). The test piece in this state was subjected to a temperature of 23 ℃ and a relative humidity of 55% in an atmosphere in accordance with JIS K6854-2: 1999 "adhesive-peel adhesion Strength test method-second section: 180 degree peeling "A180 degree peeling test was conducted at a jig moving speed of 300 mm/min, and an average peeling force of 170mm in length was obtained after 30mm of the jig portion was removed. The results are shown in Table 2.

(5) Formation of adhesive layer

< examples 1 to 10 and comparative example 1>

An organic solvent solution of a (meth) acrylic pressure-sensitive adhesive obtained by adding an isocyanate-based crosslinking agent and a silane coupling agent to a (meth) acrylic resin which is a copolymer of butyl acrylate, methyl acrylate, acrylic acid and hydroxyethyl acrylate was applied to a release-treated surface of a release film (trade name "SP-PLR 382052" manufactured by LINTEC) having a thickness of 38 μm formed of polyethylene terephthalate after the release treatment so that the dried thickness became 20 μm by a die coater, to produce a sheet-like pressure-sensitive adhesive with a release film. Next, the surface (adhesive surface) of the sheet-like adhesive obtained above on the side opposite to the separator was bonded to the cyclic polyolefin resin film surface of the polarizing plate produced in (2) above using a laminator, and then cured at 23 ℃ and 65% relative humidity for 7 days to obtain a polarizing plate having an adhesive layer.

(5) Formation of adhesive layer

< example 11>

An organic solvent solution of a (meth) acrylic pressure-sensitive adhesive obtained by adding an isocyanate-based crosslinking agent and a silane coupling agent to a (meth) acrylic resin which is a copolymer of butyl acrylate, methyl acrylate, acrylic acid and hydroxyethyl acrylate was applied by a die coater to a release-treated surface of a release film (trade name "SP-PLR 382052" manufactured by LINTEC) having a thickness of 38 μm and formed of polyethylene terephthalate after the release treatment so that the dried thickness became 20 μm, to produce a sheet-like pressure-sensitive adhesive with a release film. Next, the surface (adhesive surface) of the sheet-like adhesive obtained above on the side opposite to the separator was bonded to the polyester resin film surface of the polarizing plate produced in (2) above using a laminator, and then cured at 23 ℃ and 65% relative humidity for 7 days to obtain a polarizing plate having an adhesive layer.

(5) Formation of adhesive layer

< example 12>

An organic solvent solution of a (meth) acrylic pressure-sensitive adhesive obtained by adding an isocyanate-based crosslinking agent and a silane coupling agent to a (meth) acrylic resin which is a copolymer of butyl acrylate, methyl acrylate, acrylic acid and hydroxyethyl acrylate was applied by a die coater to a release-treated surface of a release film (trade name "SP-PLR 382052" manufactured by LINTEC) having a thickness of 38 μm and formed of polyethylene terephthalate after the release treatment so that the dried thickness became 20 μm, to produce a sheet-like pressure-sensitive adhesive with a release film. Next, the surface (adhesive surface) of the sheet-like adhesive obtained above on the side opposite to the separator was bonded to the acetyl cellulose resin film surface of the polarizing plate produced in (2) above using a laminator, and then cured at 23 ℃ and 65% relative humidity for 7 days to obtain a polarizing plate having an adhesive layer.

(6) Evaluation of Wet Heat durability of polarizing plate

The adhesive layer-attached polarizing plate produced in (5) above was cut into a size of 30mm × 30mm, and the separator was peeled off to bond the exposed adhesive layer surface to the glass substrate. The glass substrate used was an alkali-free glass product "Eagle XG" manufactured by corning corporation. The optical laminate thus obtained was measured for MD transmittance and TD transmittance at wavelengths in the range of 380 to 780nm using an integrating sphere-equipped spectrophotometer (product name "V7100" manufactured by japan spectro corporation), and the monomer transmittance at each wavelength was calculated, and then measured according to JIS Z8701: 1999 "color expression method-XYZ color system and X₁₀Y₁₀Z₁₀Visibility was corrected for the 2-degree field of view (C light source) of the color system "to obtain the visibility corrected individual transmittance (Ty) before the endurance test. The optical laminate was provided in the spectrophotometer with an integrating sphere such that the side of the polarizing plate on which the cyclic polyolefin resin film was provided was the probe side and light entered from the glass substrate side.

The monomer transmittance is defined by the formula (λ) 0.5 × (Tp (λ) + Tc (λ)). Tp (λ) is the transmittance (%) of the optical laminate measured in relation to the incident linear polarized light of wavelength λ (nm) and the parallel nicols, and Tc (λ) is the transmittance (%) of the optical laminate measured in relation to the incident linear polarized light of wavelength λ (nm) and the orthogonal nicols.

Next, the optical laminate was left to stand in a moist heat environment at a temperature of 80 ℃ and a relative humidity of 90% for 24 hours, and then left to stand in an environment at a temperature of 23 ℃ and a relative humidity of 60% for 24 hours, and then Ty after the endurance test was determined by the same method as before the endurance test. The increase rate of Ty was calculated from Ty before and after the endurance test based on the following equation, and was determined according to the following criteria. The results are shown in Table 2.

The increase rate of Ty { (Ty after durability test-Ty before durability test)/Ty before durability test } × 100

< evaluation criteria for Wet Heat durability >

4: the increase rate of the monomer transmittance (. DELTA.Ty) was less than 6%.

3: the increase rate of the monomer transmittance (Δ Ty) is 6% or more and less than 10%.

2: the increase rate of the monomer transmittance (Δ Ty) is 10% or more and less than 80%.

1: the increase rate of the monomer transmittance (Δ Ty) is 80% or more.

[ Table 1]

[ Table 2]

As shown in table 2, it was confirmed that: the polarizing plate obtained in example was superior to the polarizing plate obtained in comparative example 1 in all of adhesiveness, appearance, and moisture and heat durability.

Description of the reference numerals

10 … first protective film, 15 … first adhesive layer, 20 … second protective film, 25 … second adhesive layer, and 30 … polarizing plate

Claims (5)

1. A polarizing plate comprising a polarizer and a protective film laminated on at least one surface of the polarizer via an adhesive layer comprising a cationically polymerizable compound, a first acid generator The cured product of the binder of the agent and the second acid generator, The first acid generator is an ionic compound having a curing temperature of less than 120°C, and is an ionic compound represented by the following formula (3),

In formula (3), R ¹¹ and R ¹² independently represent an alkyl group, an aralkyl group, an aryl group or an aromatic heterocyclic group, R ¹³ represents an optionally substituted phenyl group, ^and X- is the following formula ( an anion represented by 1) or an anion represented by the following formula (2),

In formula (1), R ¹ is an optionally substituted C _6-14 aryl group or an optionally substituted C _3-14 aromatic heterocyclic group, and R ² to R ⁴ are independently C _{1- 18} alkyl group, optionally substituted C _6-14 aryl group or optionally substituted C _3-14 aromatic heterocyclic group, the substituent group is 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, alkane represented by -OR ⁵ Oxy group or aryloxy group, acyl group represented by R ⁶ CO-, acyloxy group represented by R ⁷ COO-, alkylthio or arylthio group represented by -SR ⁸ , amino group represented by -NR ⁹ R ¹⁰ , or a halogen atom, the R ⁵ to R ⁸ are C _1-8 alkyl groups, C _6-14 aryl groups or C _3-14 aromatic heterocyclic groups, and the R ⁹ and R ¹⁰ are hydrogen atoms, C _{1 -8} alkyl, C _6-14 aryl or C _3-14 aromatic heterocyclic group,

In formula (2), Rf represents the same or different alkyl groups in which 80% or more of hydrogen is substituted by fluorine atoms, and a is an integer of 1 to 5, The second acid generator is an ionic compound that has a curing temperature of 120° C. or higher and generates an acid using active energy rays, The second acid generator is an ionic compound represented by the following formula (4),

In formula (4), R ¹⁴ and R ¹⁵ independently represent an alkyl group, an aralkyl group, an aryl group or an aromatic heterocyclic group, R ¹⁶ represents an optionally substituted phenyl group, ^and Y- is the formula ( 1) or an anion represented by the formula (2), or PF ₆ ⁻ . 2 . The polarizing plate according to claim 1 , wherein the adhesive layer is an adhesive layer cured by heating the adhesive after irradiating the adhesive with active energy rays. 3 . 3 . The polarizing plate according to claim 1 , wherein the cationically polymerizable compound contains at least one compound selected from the group consisting of epoxy compounds, oxetane compounds, and vinyl compounds. 4 . 4 . The polarizing plate according to claim 1 , wherein the protective film is selected from the group consisting of cellulose-based resins, (meth)acrylic-based resins, polyolefin-based resins, polyester-based resins, and polycarbonate-based resins. 5 . of at least one resin. 5. A method for manufacturing a polarizing plate according to any one of claims 1 to 4, comprising: (a) the process of coating the adhesive on the polarizer and/or the protective film; (b) the process of laminating the polarizer and the protective film; (c) a step of irradiating the laminate obtained in the step (b) with an active energy ray; and (d) Next, the step of heating the laminate.

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