TWI852905B - Optical laminate - Google Patents

Abstract

The present invention provides an optical laminate which is capable of effectively suppressing migration of a dichroic dye contained in a polarizing film to a conductive layer and preventing deterioration of the conductive layer.

The optical laminate of the present invention includes a first cured material layer composed of a cured product of a curable composition containing a polymerizable compound, an adhesive layer, and a conductive layer laminated in this order, on one surface of a polarizing film containing a dichroic dye in a polyvinyl alcohol-based resin； wherein the first cured material layer has an absorbance increase rate represented by the following formula (1) of 30% or less.

Absorbance increase rate (%)=(after immersion Abs (360nm)-before immersion Abs (360nm))/before immersion Abs (360 nm)×100 (1)

Description

Optical laminates

The present invention relates to an optical multilayer body which can be used in image display panels and the like.

Conventionally, it is known that a dichroic dye such as iodine is adsorbed and aligned on one side of a polarizing film of a polyvinyl alcohol resin film, and an optical laminate having a protective film is laminated via an adhesive. The adhesive used to form such an optical laminate, for example, is described in Patent Document 1 as a photo-cation-curable adhesive (curable composition) containing aliphatic epoxides, alicyclic epoxides and/or oxycyclobutane and a photopolymerization initiator, and the cured product thereof functions as an adhesive.

In recent years, transparent conductive films such as indium tin oxide (ITO) thin films have been widely used in display devices. For example, the transparent conductive film is formed on the opposite side of the liquid crystal layer contact side of the transparent substrate constituting the liquid crystal cell of the liquid crystal display device using the in-plane switching (IPS) method, as a charge prevention layer. In addition, the transparent conductive film formed on the transparent resin film is used as an electrode substrate of a touch panel, such as a combination of a liquid crystal display device used in a mobile phone, a portable music player, etc., and an image display device and an input device of the touch panel, and has been widely used.

[Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Application Publication No. 2008-063397

However, when a conductive layer such as an ITO layer is laminated on the polarizing film side of the optical laminate described in Patent Document 1 via an adhesive layer, the dichroic dye contained in the polarizing film is likely to migrate to the conductive layer through the adhesive layer, and may cause malfunctions such as poor sensing. The migration of the dichroic dye from the polarizing film is particularly significant in a high temperature and high humidity environment, so there is a need for an optical laminate that can prevent the conductive layer from being deteriorated due to the dichroic dye contained in the polarizing film migrating to the conductive layer via the adhesive layer even in a high temperature and high humidity environment.

Therefore, an object of the present invention is to provide an optical laminate that can effectively suppress the migration of dichroic dyes contained in a polarizing film toward a conductive layer and prevent the conductive layer from deteriorating.

The present invention provides the following preferred aspects [1] to [6].

[1] An optical laminate comprising a first cured layer, an adhesive layer and a conductive layer, which are sequentially laminated on one side of a polarizing film containing a dichroic dye in a polyvinyl alcohol resin; wherein the absorbance increase rate of the first cured layer represented by the following formula (1) is 30% or less; absorbance increase rate (%) = (Abs (360nm) after immersion - Abs (360nm) before immersion) / Abs (360nm) before immersion × 100 (1)

[Wherein, Abs (360 nm) after immersion represents the absorbance at 360 nm after the cured product is immersed in a 50% potassium iodide aqueous solution for 100 hours in an atmosphere at a temperature of 23°C and a relative humidity of 60%, and Abs (360 nm) before immersion represents the absorbance at 360 nm before the cured product is immersed in a 50% potassium iodide aqueous solution].

[2] An optical laminate comprising a first curable layer, an adhesive layer and a conductive layer, which are sequentially laminated on one side of a polarizing film containing a dichroic dye in a polyvinyl alcohol-based resin; wherein the polymerizable compound comprises an oxycyclobutane compound having two or more oxycyclobutane groups, and the content of the oxycyclobutane compound is 40 parts by mass or more relative to 100 parts by mass of the total amount of all polymerizable compounds contained in the curable composition.

[3] The optical laminate according to [1] or [2], wherein the thickness of the first hardened layer is 0.1 to 15 μm.

[4] The optical laminate according to any one of [1] to [3], wherein the cured material constituting the first cured material layer is a photocurable material of a curable composition comprising the polymerizable compound.

[5] The optical multilayer structure according to any one of [1] to [4], wherein a second cured layer and a protective film are laminated on the surface of the polarizing film opposite to the first cured layer.

[6] The optical laminate according to [5], wherein the moisture permeability of the protective film is less than 1200 g/24 hours at a temperature of 23°C and a relative humidity of 55%.

The optical multilayer body of the present invention can inhibit the dichroic pigment contained in the polarizing film from moving toward the conductive layer and can effectively inhibit the corrosion of the conductive layer.

1. Polarizing film

2. First hardening layer

3. Adhesive layer

4. Conductive layer

5. The second hardening layer

6. Second protective film

7. First protective film

10. Optical multilayers

X‧‧‧Substrate

FIG. 1 is a cross-sectional view showing the structure of one embodiment of the optical laminate of the present invention.

FIG. 2 is a cross-sectional view showing the structure of one embodiment of the optical laminate of the present invention.

The following is a detailed description of the implementation of the present invention. The scope of the present invention is not limited to the implementation described here, and various modifications can be made without damaging the gist of the present invention.

FIG. 1 illustrates the structure of one embodiment of the optical laminate of the present invention. The optical laminate 10 of the present invention has a structure in which a first hardened layer 2, an adhesive layer 3, and a conductive layer 4 are sequentially laminated on one side of a polarizing film 1. If necessary, a protective film 6 may be provided on the side opposite to the first hardened layer 2 of the polarizing film 1 via a second hardened layer 5. In the embodiment of FIG. 1, the conductive layer 4 of the optical laminate 10 is laminated on a substrate X.

Furthermore, the optical laminate of the present invention may include a first protective film 7 between the first cured layer 2 and the adhesive layer 3. This embodiment is shown in FIG. 2. In the optical laminate 10, a protective film 6 may be provided on the surface of the polarizing film 1 opposite to the first cured layer 2 via the second cured layer 5, as required. Furthermore, in the embodiment of FIG. 2, the conductive layer 4 of the optical laminate 10 is laminated on the substrate X.

The following is a detailed description of the components of the optical multilayer structure of the present invention.

[1st hardened layer]

The optical multilayer body of the present invention has a first cured material layer composed of a cured product of a curable composition containing a polymerizable compound (hereinafter sometimes referred to as curable composition (1)) on one side of a polarizing film containing a dichroic dye in a polyvinyl alcohol-based resin.

The absorbance increase rate of the first cured layer expressed by the following formula (1) is 30% or less. Absorbance increase rate (%) = (Abs (360nm) after immersion - Abs (360nm) before immersion) / Abs (360nm) before immersion × 100 (1) [wherein Abs (360nm) after immersion represents the absorbance at 360nm after the cured material is immersed in a 50% potassium iodide aqueous solution for 100 hours in an atmosphere at a temperature of 23°C and a relative humidity of 60%, and Abs (360nm) before immersion represents the absorbance at 360nm before the cured material is immersed in a 50% potassium iodide aqueous solution].

Even if the first cured layer is immersed in a 50% potassium iodide aqueous solution for 100 hours, the absorbance increase rate expressed by the above formula (1) is less than 30%. This means that the first cured layer has a low absorptivity to iodine (dichroic dye). Therefore, the optical laminate of the present invention can effectively inhibit the migration of iodine (dichroic dye) contained in the polarizing film to the first cured layer, and can prevent the corrosion of the conductive layer (such as ITO layer) caused by iodine (dichroic dye). Furthermore, the optical performance of the optical laminate can also be maintained.

The absorbance increase rate represented by the above formula (1) is preferably 25% or less, more preferably 20% or less, even more preferably 15% or less, and particularly preferably 10% or less. When the absorbance increase rate is below the above value, as described above, the migration of iodine (dichroic dye) contained in the polarizing film to the first cured layer can be more effectively suppressed, and the corrosion of the conductive layer and the reduction in the optical performance of the optical laminate can be more effectively prevented.

The polymerizable compound contained in the curable composition (1) is not particularly limited as long as it can form a cured product constituting the first cured product layer. Examples of the polymerizable compound include active energy ray-curable resin compositions, water-soluble resin compositions, water-dispersible resin compositions, etc. Among them, active energy ray-curable resin compositions are preferred from the viewpoint of simplifying the process, and (meth)acrylate compounds including epoxy acrylate, amine acrylate, etc., acrylamide compounds, cyclohexane compounds, and epoxy compounds are particularly preferred.

In a preferred embodiment, the hardener constituting the first hardener layer is a light-curable material of a hardening composition including a polymerizable compound. Therefore, the polymerizable compound is preferably a photopolymerizable compound.

The polymerizable compound is preferably an oxycyclobutane compound having two or more oxycyclobutane groups (oxycyclobutane rings) in the molecule (hereinafter sometimes referred to as "oxycyclobutane compound (A)").

The cyclohexane compound (A) is a compound having two or more cyclohexane groups in the molecule, and may be an aliphatic compound, an alicyclic compound, or an aromatic compound. Specific examples of the cyclohexane compound (A) include 1,4-bis[{(3-ethylcyclohexane-3-yl)methoxy}methyl]benzene (also called diphenylene cyclohexane), bis(3-ethyl-3-cyclohexane methyl)ether, and the like. These cyclohexane compounds (A) may be used alone or in combination. By including the cyclohexane compound (A), a high crosslinking density and a dense hardened material may be obtained. By placing a hardened material layer with a high cross-linking density on one side of the polarizing film, the migration of the dichroic dye from the polarizing film can be effectively suppressed.

The content of the cyclohexane compound (A) is, for example, 40 parts by mass or more, preferably 45 parts by mass or more, and more preferably 50 parts by mass or more, relative to 100 parts by mass of the total amount of all polymerizable compounds contained in the curable composition (1). Furthermore, the content of the cyclohexane compound (A) is preferably 90 parts by mass or less, more preferably 80 parts by mass or less, even more preferably 70 parts by mass or less, and particularly preferably 65 parts by mass or less, relative to 100 parts by mass of the total amount of all polymerizable compounds contained in the curable composition (1). Furthermore, the content of the cyclohexane compound (A) may be a combination of the lower limit and the upper limit, preferably 40 to 65 parts by mass, more preferably 45 to 60 parts by mass, based on 100 parts by mass of the total amount of all polymerizable compounds contained in the curable composition (1).

Furthermore, the content of the oxycyclobutane compound (A) is, for example, 35 parts by mass or more, preferably 40 parts by mass or more, and more preferably 45 parts by mass or more, relative to 100 parts by mass of the total amount of the curable composition (1). When the content of the oxycyclobutane compound (A) is greater than the above value, the migration of the dichroic dye contained in the polarizing film to the first cured layer can be more effectively suppressed, and the corrosion of the conductive layer and the reduction in the optical performance of the optical laminate can be more effectively prevented.

The polymerizable compound preferably further contains an epoxy compound (B). The epoxy compound (B) is preferably at least one selected from (B1) an aliphatic epoxy compound having two or more epoxy groups (hereinafter sometimes referred to as "aliphatic epoxy compound (B1)"), (B2) an alicyclic epoxy compound having two or more epoxy groups (hereinafter sometimes referred to as "alicyclic epoxy compound (B2)"), and (B3) an aromatic epoxy compound having one or more aromatic rings (hereinafter sometimes referred to as "aromatic epoxy compound (B3)").

The aforementioned aliphatic epoxy compound (B1) is a compound having at least two cyclobutane rings bonded to aliphatic carbon atoms in the molecule. Examples of the aliphatic epoxy compound (B1) include bifunctional epoxy compounds such as 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, and neopentyl glycol diglycidyl ether; and trifunctional or higher epoxy compounds such as trihydroxymethylpropane triglycidyl ether and neopentyltriol tetraglycidyl ether.

When an aliphatic epoxy compound (B1) is contained, from the viewpoint of adhesion between the polarizing film and the protective film or the adhesive layer, an epoxy compound having two oxycyclobutane rings bonded to an aliphatic carbon atom in the molecule (also called an aliphatic diepoxy compound) is preferred, and an aliphatic diepoxy compound represented by the following formula (I) is more preferred. When the curable composition contains an aliphatic diepoxy compound represented by the following formula (I) as the aliphatic epoxy compound (B1), a curable composition having low viscosity and being easy to apply can be obtained.

In formula (I), Z represents an alkylene group having 1 to 9 carbon atoms, an alkylene group having 3 or 4 carbon atoms, a divalent alicyclic alkyl group, or a divalent group represented by _-CmH2m - _Z1 - _CnH2n- . ^-Z1- represents -O-, -CO-O-, -O-CO-, ^-SO2- , _-SO- , _or CO-, and m and n each independently represent an integer greater than or equal to 1. However, the total of m and n is 9 or less.

The divalent alicyclic hydrocarbon group may be, for example, an alicyclic hydrocarbon group having 4 to 8 carbon atoms, for example, a divalent residual group represented by the following formula (I-1).

Specific examples of the compound represented by formula (I) include diglycidyl ether of alkanediol; diglycidyl ether of oligomeric alkanediol having a repeating number of 4 or less; and diglycidyl ether of alicyclic glycol.

Examples of glycols that can form the compound represented by the aforementioned formula (I) include ethylene glycol, propylene glycol, 1,3-propylene glycol, 2-methyl-1,3-propylene glycol, 2-butyl-2-ethyl-1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 3-methyl-2,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 3,5-heptanediol, 1,8-octanediol, 2-methyl-1,8-octanediol, and 1,9-nonanediol; Oligoalkylene glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol and dipropylene glycol; alicyclic glycols such as cyclohexanediol and cyclohexanedimethanol; and the like.

In the present invention, the aliphatic epoxy compound (B1) is preferably 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and neopentyl glycol diglycidyl ether from the viewpoint of being able to form a curable composition with low viscosity and easy coating. 1,6-hexanediol diglycidyl ether and neopentyl glycol polyglycidyl ether are preferred from the viewpoint of being able to maintain optical properties. The aliphatic epoxy compound (B1) may be used alone or in combination of a plurality of different aliphatic epoxy compounds.

When the curable composition (1) contains an aliphatic epoxy compound (B1), the content of the aliphatic epoxy compound (B1) is preferably 1 to 40 parts by mass, more preferably 3 to 30 parts by mass, more preferably 5 to 20 parts by mass, and particularly preferably 7 to 15 parts by mass, based on 100 parts by mass of the total amount of all polymerizable compounds contained in the curable composition. When the content of the aliphatic epoxy compound (B1) is within the above range, the curable composition (1) has a low viscosity and can be a composition that is easy to apply.

表示的構造之橋接的氧原子-O-。上述式(a)中，m為2 至5的整數。 The aforementioned alicyclic epoxy compound (B2) is a compound having two or more epoxy groups bonded to an alicyclic ring in the molecule. The so-called "epoxy group bonded to an alicyclic ring" refers to the following formula (a):

In the above formula (a), m is an integer of 2 to 5.

By removing one or more hydrogen atoms in (CH ₂ ) _m of the above formula (a), two or more radicals are bonded to other chemical structures to form alicyclic epoxy compounds (B2). One or more hydrogen atoms in (CH ₂ ) _m may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group.

Among them, from the viewpoint of high glass transition temperature of the cured product and good adhesion between the polarizing film and the protective film, alicyclic epoxy compounds having an epoxycyclopentane structure [where m=3 in the above formula (a)] and an epoxycyclohexane structure [where m=4 in the above formula (a)] are preferred, and alicyclic diepoxy compounds represented by the following formula (II) are more preferred. When the curable composition (1) contains the alicyclic diepoxy compound represented by the following formula (II) as the compound (B2), the elasticity of the cured product layer after the curable composition is cured becomes high, and cracking due to thermal shrinkage of the polarizing film can be suppressed.

In formula (II), ^R1 and ^R2 each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. When the alkyl group has 3 or more carbon atoms, it may have an alicyclic structure. The alkyl group having 1 to 6 carbon atoms may be a linear or branched alkyl group. Examples of the alkyl group having an alicyclic structure include cyclopropyl, cyclobutyl, and cyclopentyl.

In formula (II), X represents an oxygen atom, an alkanediyl group having 1 to 6 carbon atoms, or the following formulas (IIa) to (IId):

之任一者表示的2價基。

A divalent group represented by any one of .

Examples of the alkanediyl group having 1 to 6 carbon atoms include methylene, ethylidene, and propane-1,2-diyl.

When X in formula (II) is a divalent group represented by any one of formulas (IIa) to (IId), ^Y1 to ^Y4 in each formula are independently an alkanediyl group having 1 to 20 carbon atoms, and when the alkanediyl group has 3 or more carbon atoms, it may have an alicyclic structure.

a and b independently represent integers from 0 to 20.

Examples of the compound represented by formula (II) include the following compounds A to G. In addition, the chemical formulas A to G shown below correspond to compounds A to G, respectively.

A: 3,4-Epoxycyclohexylcarboxylic acid 3,4-Epoxycyclohexylmethyl ester

B: 3,4-Epoxy-6-methylcyclohexylcarboxylic acid 3,4-Epoxy-6-methylcyclohexyl methyl ester

C: Ethylene bis(3,4-epoxycyclohexylcarboxylate)

D: Di(3,4-epoxycyclohexylmethyl adipate)

E: Di(3,4-epoxy-6-methylcyclohexyl) adipate

F: Diethylene glycol bis(3,4-epoxycyclohexyl methyl ether)

G: Ethylene glycol bis(3,4-epoxycyclohexyl methyl ether)

A:

B:

C:

D:

E:

F:

G:

In the present invention, the alicyclic epoxy compound (B2) is preferably 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate from the viewpoint of easy availability. Furthermore, from the viewpoint of effectively suppressing corrosion of the conductive layer, it is preferably 1,2-epoxy-4-(2-oxacyclobutane)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol. In particular, when 3,4-epoxycyclohexylcarboxylic acid 3,4-epoxycyclohexylmethyl ester and 1,2-epoxy-4-(2-oxacyclobutane)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol are used in combination as the alicyclic epoxy compound (B2), corrosion of the conductive layer can be more effectively suppressed. The alicyclic epoxy compound (B2) may be used alone or in combination of a plurality of different alicyclic epoxy compounds.

When the curable composition (1) contains the alicyclic epoxy compound (B2), the content of the alicyclic epoxy compound (B2) is preferably 3 to 70 parts by mass, more preferably 10 to 60 parts by mass, even more preferably 20 to 55 parts by mass, and particularly preferably 25 to 50 parts by mass, relative to 100 parts by mass of the total amount of all polymerizable compounds contained in the curable composition (1). When the content of the alicyclic epoxy compound (B2) is within the above range, curing due to irradiation with active energy rays such as ultraviolet rays can be accelerated, and a cured layer having sufficient hardness can be easily formed.

The aromatic epoxy compound (B3) is a compound having one or more aromatic rings in the molecule, and specific examples thereof include the following.

Monovalent phenols having at least one aromatic ring, such as phenol, cresol, butylphenol, or mono/polyglycidyl ether compounds of epoxide adducts thereof, such as glycidyl ether compounds of bisphenol A, bisphenol F, or such compounds to which epoxide is added, and epoxyphenolic resins; glycidyl ether compounds of aromatic compounds having two or more phenolic hydroxyl groups, such as resorcinol, hydroquinone, and catechol; mono/polyglycidyl ether compounds of aromatic compounds having two or more alcoholic hydroxyl groups, such as benzyl alcohol, benzyl alcohol, and benzyl butanol; glycidyl esters of polyprotic aromatic compounds having two or more carboxylic acids, such as phthalic acid, terephthalic acid, and trimellitic acid; epoxy esters of benzoic acids such as benzoic acid, toluic acid, and naphthoic acid; Propyl ester; epoxide of styrene oxide or divinylbenzene, etc.

When the aromatic epoxy compound (B3) is contained, it is preferred to contain at least one selected from the group consisting of phenolic glycidyl ethers, glycidyl ether compounds of aromatic compounds having two or more alcoholic hydroxyl groups, polyvalent phenolic glycidyl ether compounds, benzoic acid glycidyl esters, polyprotic acid glycidyl esters, styrene oxide or epoxides of divinylbenzene from the viewpoint of lowering the viscosity of the curable composition.

Furthermore, the aromatic epoxy compound (B3) preferably has an epoxy equivalent of 80 to 500 in order to improve the curability of the curable composition.

The aromatic epoxy compound (B3) may be used alone or in combination of a plurality of different types.

As the aromatic epoxy compound (B3), commercially available products may be used, for example, Denacol EX-121, Denacol EX-141, Denacol EX-142, Denacol EX-145, Denacol EX-146, Denacol EX-147, Denacol EX-201, Denacol EX-203, Denacol EX-711, Denacol EX-721, Oncoat EX-1020, Oncoat EX-1030, Oncoat EX-1040, Oncoat EX-1050, Oncoat EX-1051, Oncoat EX-1010, Oncoat EX-1011, Oncoat EX-1012 (all manufactured by Nagase Chemtex Co., Ltd.); Ogsol PG-100, Ogsol EG-200, Ogsol EG-210, Ogsol EG-250 (all manufactured by Osaka Gas Chemical Co., Ltd.); HP4032, HP4032D, HP4700 (all manufactured by DIC Corporation); ESN-475V (manufactured by Nippon Steel & Sumitomo Chemical Co., Ltd.); Epicoat YX8800, jER828EL (manufactured by Mitsubishi Chemical Corporation); Marproof G-0105SA, Marproof G-0130SP (manufactured by NOF Corporation); Epiclone N-665, Epiclone HP-7200 (all manufactured by DIC Corporation); EOCN-1020, EOCN-102S, EOCN-103S, EOCN-104S, XD-1000, NC-3000, EPPN-501H, EPPN-501HY, EPPN-502H, NC-7000L (all manufactured by Nippon Kayaku Co., Ltd.); Adeka Glycilol ED-501, Adeka Glycilol ED-502, Adeka Glycilol ED-509, Adeka Glycilol ED-529, Adeka Resin EP-4000, Adeka Resin EP-4005, Adeka Resin EP-4100, Adeka Resin EP-4901 (the above are made by ADEKA); TECHMORE VG-3101L, EPOX-MKR710, EP OX-MKR151 (the above are manufactured by Printech Co., Ltd.), etc.

The curable composition contains an aromatic epoxy compound (B3), and the curable composition becomes a hydrophobic resin, and the resulting cured layer also becomes hydrophobic. Therefore, under high temperature and high humidity conditions, it can prevent water from entering from the outside and effectively inhibit the migration of the dichroic pigment (iodine) contained in the polarizing film.

When the curable composition (1) contains an aromatic epoxy compound (B3), the content of the aromatic epoxy compound (B3) is preferably 1 to 70 parts by mass, more preferably 5 to 60 parts by mass, even more preferably 7 to 55 parts by mass, and particularly preferably 10 to 50 parts by mass, relative to 100 parts by mass of the total amount of all polymerizable compounds contained in the curable composition (1). When the content of the aromatic epoxy compound (B3) is within the above range, the hydrophobicity of the cured layer can be improved, and the permeability of the dichroic dye (iodine) to the cured layer can be reduced.

When the curable composition (1) contains the cyclohexane compound (A) and the alicyclic epoxy compound (B2), the mass ratio (WB2/WA) of the alicyclic epoxy compound (B2) content (WB2) to the cyclohexane compound (A) content (WA) is preferably 0.05 to 1.5.

When the curable composition (1) contains an oxycyclobutane compound (A) and an aliphatic epoxy compound (B1), the mass ratio (WB1/WA) of the content (WB1) of the aliphatic epoxy compound (B1) to the content (WA) of the oxycyclobutane compound (A) is preferably 0.1 to 0.5.

When the curable composition (1) contains an oxycyclobutane compound (A) and an aromatic epoxy compound (B3), the mass ratio (WB3/WA) of the content (WB3) of the aromatic epoxy compound (B3) to the content (WA) of the oxycyclobutane compound (A) is preferably 0.1 to 1.5.

The curable composition (1) may contain a polymerizable compound other than the cyclohexane compound (A) and the epoxy compound (B), and specifically, may include an aliphatic monoepoxy compound and an alicyclic monoepoxy compound.

The content of the polymerizable compound contained in the curable composition (1) is preferably 80 to 100 parts by mass, more preferably 90 to 99.5 parts by mass, and even more preferably 95 to 99 parts by mass, relative to 100 parts by mass of the total amount of the curable composition (1). When the content of the polymerizable compound is within the above range, the migration of the dichroic dye contained in the polarizing film to the first cured layer can be effectively suppressed.

The curable composition usually contains a polymerization initiator for initiating polymerization. The polymerization initiator may be a photopolymerization initiator (e.g., a photocationic polymerization initiator, a photoradical polymerization initiator) or a thermal polymerization initiator. For example, when the curable composition contains the aforementioned cyclohexane compound (A), epoxy compound (B), etc. as a polymerizable compound, it is preferred to use a photocationic polymerization initiator as the polymerization initiator.

Photo-cationic polymerization initiators are compounds that generate cationic substances or Lewis acids by irradiation with active energy rays such as visible light, ultraviolet rays, X-rays, or electron beams, and are used to initiate polymerization reactions of cationic polymerizable compounds. Photo-cationic polymerization initiators are photocatalytic, so even when mixed with polymerizable compounds, they have good storage stability and operability. Examples of compounds that generate cationic substances or Lewis acids by irradiation with active energy rays include aromatic iodonium salts, onium salts of aromatic sulfonium salts, aromatic diazonium salts, and iron-arene complexes.

An aromatic iodine salt is a compound having a diaromatic iodine cation, and the cation is typically a diphenyliodine cation. An aromatic sulfonium salt is a compound having a triaromatic sulfonium cation, and the cation is typically a triphenylsulfonium cation, 4,4'-bis(diphenylsulfonium)diphenyl sulfide cation, etc. An aromatic diazonium salt is a compound having a diazonium cation, and the cation is typically a benzene didiazonium cation. Furthermore, the iron-arene complex is typically a cyclopentadienyl iron (II) arene complex.

The cations shown above form pairs with anions to form a photocationic polymerization initiator. Examples of anions constituting the photocationic polymerization initiator include special phosphorus anions [(Rf) _n PF _6-n ] ^- , hexafluorophosphate anions PF ₆ ^- , hexafluoroantimony acid anions SbF ₆ ^- , pentafluorohydroxyantimony acid anions SbF ₅ (OH) ^- , hexafluoroarsenic acid anions AsF ₆ ^- , tetrafluoroborate anions BF ₄ ^- , tetrakis(pentafluorophenyl)boric acid anions B(C ₆ F ₅ ) ₄ ^- and the like. Among them, from the viewpoint of the curability of the polymerizable compound and the safety of the obtained cured layer, the photocatalytic polymerization initiator is preferably a special phosphorus anion [(Rf) _n PF _6-n ] ^- or a hexafluorophosphate anion PF ₆ ^- .

Photocatalytic ion polymerization initiators may be used alone or in combination. Among them, aromatic sulfonium salts are preferred because they have ultraviolet absorption properties in the wavelength region around 300nm, have good curing properties, and can produce a cured product with good mechanical strength and adhesive strength.

The content of the polymerization initiator in the curable composition (1) is usually 0.5 to 10 parts by mass, preferably 6 parts by mass or less, and more preferably 3 parts by mass or less, relative to 100 parts by mass of the polymerizable compound. When the content of the polymerization initiator is within the above range, the polymerizable compound can be sufficiently cured, and a high mechanical strength and adhesive strength can be imparted to the cured layer formed from the obtained cured product. On the other hand, when the amount becomes too large, the product from the photo-cationic polymerization initiator reacts with the hydroxyl group of the polyvinyl alcohol constituting the polarizing film, which may reduce the optical performance of the polarizing film.

In the present invention, the curable composition (1) may contain additives commonly used in curable compositions as needed. Such additives include, for example, ion scavengers, antioxidants, chain transfer agents, polymerization accelerators (polyols, etc.), sensitizers, sensitizing aids, light stabilizers, tackifiers, thermoplastic resins, fillers, flow regulators, plasticizers, defoamers, leveling agents, silane coupling agents, pigments, antistatic agents, ultraviolet absorbers, etc.

The sensitizer may be, for example, a photosensitizer. A photosensitizer is a compound that exhibits maximum absorption at a wavelength longer than the maximum absorption wavelength exhibited by a photocationic polymerization initiator and promotes the polymerization initiation reaction by the photocationic polymerization initiator. Moreover, a photosensitizing auxiliary is a compound that further promotes the action of the photosensitizer. Depending on the type of protective film, it is better to prepare such a photosensitizer and then a photosensitizing auxiliary. By preparing such photosensitizers, a photosensitizing auxiliary can form a cured product with the desired properties even when a film with low UV transmittance is used.

The photosensitizer is preferably a compound that exhibits maximum absorption at a wavelength longer than 380 nm. Examples of such photosensitizers include the anthracene compounds described below.

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

The curable composition (1) can be obtained by mixing a polymerizable compound and a polymerization initiator and additives as required. The first curable layer can be formed by applying the curable composition (1) on a polarizing film or on a first protective film when a first protective film is used, and curing the applied curable composition by irradiating it with active energy rays such as ultraviolet rays and electron beams.

The curable composition (1) can be applied by various coating methods such as a scraper, a wire rod, a slit coater, a notch wheel coater, a gravure coater, etc. The light source used to cure the curable composition (1) is, for example, a light source of active energy rays. The light source of active energy rays may be, for example, any light source that generates ultraviolet rays, electron rays, X-rays, etc. In particular, a light source having a luminescence distribution at a wavelength of 400 nm or less is preferred, such as a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a chemical lamp, a black light lamp, a microwave-excited mercury lamp, a metal halide lamp, etc.

The light irradiation intensity when curing the curable composition varies depending on the composition, but the light irradiation intensity in the wavelength region effective for activating the polymerization initiator is preferably 0.1 to 1000 mW/ ^cm2 . If the light irradiation intensity when curing the curable composition (1) is too low, the time required for the reaction to proceed sufficiently becomes long. On the contrary, if the light irradiation intensity is too high, the heat radiated from the lamp and the heat generated during the polymerization of the curable composition (1) may cause deterioration of the attached film. The light irradiation time when curing the curable composition (1) is controlled by the entire composition and is not particularly limited. However, the accumulated light amount expressed as the product of the light irradiation intensity and the light irradiation time is preferably set to 10 to 5000 mJ/ ^cm2 . If the accumulated light amount is too small, the generation of active substances from the polymerization initiator is insufficient, and the resulting curing may become insufficient. On the other hand, if the accumulated light amount is too large, the irradiation time becomes very long, which is disadvantageous in improving productivity.

Furthermore, when the curable composition is cured by irradiation with active energy rays, it is preferred to perform the curing under the condition that various functions of the optical laminate, such as the degree of polarization, transmittance and hue of the polarizing film and the transparency of various films constituting the protective film and the optical layer, are not reduced.

In the optical laminate of the present invention, the thickness of the first cured layer is not particularly limited, but is preferably 0.1 to 15 μm, more preferably 0.5 to 10 μm, and even more preferably 0.5 to 7 μm. When the thickness of the first cured layer is above the lower limit, the migration of the dichroic dye can be effectively suppressed, and when it is below the upper limit, the curable composition can be sufficiently cured.

The optical laminate of the present invention has the absorbance increase rate of the first cured layer of 30%, and has low absorption of dichroic dyes. Usually, in a high temperature and high humidity environment, the migration of dichroic dyes can be accelerated due to the intrusion of moisture from the outside, but in the optical laminate of the present invention, the migration of dichroic dyes contained in the polarizing film to the first cured layer can be effectively suppressed. Therefore, even if placed in a high temperature and high humidity environment, the corrosion of the conductive layer can be effectively suppressed, and the optical performance can be maintained. Furthermore, when the adhesive layer constituting the optical laminate contains an ionic compound as an antistatic agent, for example, the ionic compound present in the adhesive layer moves toward the polarizing film through the protective film constituting the optical laminate, causing interaction with the dichroic pigment in the polarizing film, and sometimes deteriorating the optical performance of the optical laminate. The optical laminate of the present invention can effectively suppress the migration of the ionic compound from the adhesive layer because the first curing material layer is present between the polarizing film and the adhesive layer, thereby preventing the optical performance of the optical laminate from being deteriorated.

Furthermore, the first cured layer also functions as an adhesive layer for bonding the polarizing film and the protective film or adhesive layer. In this case, the optical performance of the optical laminate can be prevented from being reduced, especially for the protective film that easily penetrates ionic compounds.

[Adhesive layer]

The adhesive constituting the adhesive layer may be any conventional adhesive without particular limitation, and may be, for example, an adhesive having an acrylic resin, a rubber resin, an urethane resin, a silicone resin, a polyvinyl ether resin, etc. as a base polymer. Furthermore, an energy ray curing adhesive, a thermosetting adhesive, etc. may also be used. Among these, an adhesive having an acrylic resin as a base polymer which is excellent in transparency, adhesion, heavy workability, weather resistance, heat resistance, etc. is suitable.

In the present invention, when the adhesive layer contains an acrylic resin, the acrylic resin is not particularly limited, and conventionally known acrylic resins can be used. Among them, from the viewpoint of adhesiveness and workability, it is preferred that the adhesive layer contained in the optical laminate of the present invention contains the following acrylic resin (P).

[式中，R_a表示氫原子或甲基，R_b表示亦可被碳數1至10 的烷氧基取代的碳數1至14的烷基]所示的(甲基)丙烯酸烷酯(P1)的構造單元作為主成分，再者，包含來自具有極性官能基的不飽和單體(P2)(以下有時稱為「含有極性官能基的單體」)的構造單元之丙烯酸樹脂。 The acrylic resin (P) is derived from the following formula (III):

An acrylic resin comprising as a main component a structural unit of an alkyl (meth)acrylate (P1) represented by [wherein _Ra represents a hydrogen atom or a methyl group, and _Rb represents an alkyl group having 1 to 14 carbon atoms which may be substituted by an alkoxy group having 1 to 10 carbon atoms], and further comprising a structural unit derived from an unsaturated monomer (P2) having a polar functional group (hereinafter sometimes referred to as a "monomer containing a polar functional group").

Here, in this specification, the term "(meth)acrylic acid" means either acrylic acid or methacrylic acid, and "(meth)" also has the same meaning when referring to (meth)acrylate or the like.

Examples of the (meth)acrylic acid alkyl ester (P1) represented by formula (III) include linear alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, n-octyl acrylate and lauryl acrylate; branched alkyl acrylates such as isobutyl acrylate, 2-ethylhexyl acrylate and isooctyl acrylate; linear alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, n-octyl methacrylate and lauryl methacrylate; branched alkyl methacrylates such as isobutyl methacrylate, 2-ethylhexyl methacrylate and isooctyl methacrylate; 2-methoxyethyl acrylate, ethoxymethyl acrylate, 2-methoxyethyl methacrylate, ethoxymethyl methacrylate, etc.

Among them, n-butyl acrylate is preferred, and specifically, n-butyl acrylate is preferably 50 mass % or more based on the total amount of all monomers constituting the acrylic resin (P). The (meth) alkyl esters (P1) may be used alone or in combination of different plural types.

In the monomer (P2) containing a polar functional group, the polar functional group may be, for example, a free carboxyl group, a hydroxyl group, an amino group, a heterocyclic group headed by an epoxy group, etc. The monomer (P2) containing a polar functional group is preferably a (meth) acrylic acid compound having a polar functional group. Examples thereof include unsaturated monomers having a free carboxyl group such as acrylic acid, methacrylic acid, and β-carboxyethyl acrylate; unsaturated monomers having a hydroxyl group such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2- or 3-chloro-2-hydroxypropyl (meth)acrylate, and diethylene glycol mono(meth)acrylate; acrylamide, vinyl caprolactam, N-butylene glycol mono(meth)acrylate, and the like. - Unsaturated monomers having heterocyclic groups such as vinyl-2-pyrrolidone, tetrahydrofuran methyl (meth)acrylate, caprolactone-modified tetrahydrofuran methyl acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, glycidyl (meth)acrylate, and 2,5-dihydrofuran; unsaturated monomers having heterocyclic isocyclic amine groups such as N,N-dimethylaminoethyl (meth)acrylate, etc. These monomers containing polar functional groups may be used alone or in plural.

The monomer (P2) containing a polar functional group is preferably an unsaturated monomer having a hydroxyl group. In addition, it is also effective to use an unsaturated monomer having other polar functional groups, such as an unsaturated monomer having a free carboxyl group, in combination with the unsaturated monomer having a hydroxyl group.

In the acrylic resin (P), the amount of the structural unit derived from the (meth) alkyl ester (P1) represented by the aforementioned formula (III) is, for example, 50 to 100 parts by mass relative to 100 parts by mass of the total amount of all structural units constituting the acrylic resin (P). The amount of the structural unit derived from the monomer (P2) containing a polar functional group is, for example, 0.1 to 20 parts by mass relative to 100 parts by mass of the total amount of all structural units constituting the acrylic resin (P).

The acrylic resin (P) may also contain structural units derived from monomers different from the (meth)acrylic acid alkyl ester (P1) represented by the above formula (III) and the monomer (P2) containing a polar functional group. Examples of such structural units include structural units derived from an unsaturated monomer (P3) having one olefinic double bond and at least one aromatic ring in the molecule (hereinafter sometimes referred to as "a monomer containing an aromatic ring"), structural units derived from (meth)acrylic esters having an alicyclic structure in the molecule, structural units derived from styrene-based monomers, structural units derived from vinyl-based monomers, structural units derived from monomers having multiple (meth)acryloyl groups in the molecule, and the like.

[式中，R₃表示氫原子或甲基，n表示1至8的整數，R₄表示氫原子、碳數1至9的烷基、碳數7至11的芳烷基或碳數6至10的芳香基]表示的含有芳香環的(甲基)丙烯酸化合物為較佳。 The unsaturated monomer (monomer containing an aromatic ring) (P3) having one olefinic double bond and at least one aromatic ring in the molecule is preferably a monomer having a (meth)acryl group as the group containing the olefinic double bond. Examples thereof include benzyl (meth)acrylate, neopentyl glycol benzoate (meth)acrylate, etc., wherein the formula (IV) is:

A (meth)acrylic acid compound containing an aromatic ring represented by [wherein R ₃ represents a hydrogen atom or a methyl group, n represents an integer of 1 to 8, and R ₄ represents a hydrogen atom, an alkyl group having 1 to 9 carbon atoms, an aralkyl group having 7 to 11 carbon atoms, or an aromatic group having 6 to 10 carbon atoms] is preferred.

Examples of the alkyl group having 1 to 9 carbon atoms include methyl, butyl, nonyl, etc. Examples of the aralkyl group having 7 to 11 carbon atoms include benzyl, phenethyl, naphthylmethyl, etc. Examples of the aromatic group having 6 to 10 carbon atoms include phenyl, tolyl, naphthyl, etc.

Examples of the aromatic ring-containing (meth)acrylic acid compound represented by formula (IV) include 2-phenoxyethyl (meth)acrylate, 2-(2-phenoxyethoxy)ethyl (meth)acrylate, ethylene oxide-modified nonylphenol (meth)acrylate, 2-(o-phenylphenoxy)ethyl (meth)acrylate, etc. Such aromatic ring-containing monomers may be used alone or in combination of a plurality of different monomers. Among them, 2-phenoxyethyl (meth)acrylate [in the aforementioned formula (IV), R ₄ =H, n=1 compound], 2-(o-phenylphenoxy)ethyl (meth)acrylate [in the aforementioned formula (IV), R ₄ =o-phenyl, n=1 compound] or 2-(2-phenoxyethoxy)ethyl (meth)acrylate [in the aforementioned formula (IV), R ₄ =H, n=2 compound] is suitable as one of the aromatic ring-containing monomers (P3) constituting the acrylic resin (P).

The alicyclic structure in the structural unit of the (meth)acrylate having an alicyclic structure in the molecule is a cycloolefin structure having usually 5 or more carbon atoms, preferably 5 to 7 carbon atoms. Specific examples of acrylic acid esters having an alicyclic structure include isoborneol acrylate, cyclohexyl acrylate, dicyclopentyl acrylate, cyclododecyl acrylate, methylcyclohexyl acrylate, trimethylcyclohexyl acrylate, tert-butylcyclohexyl acrylate, α-ethoxycyclohexyl acrylate, cyclohexylphenyl acrylate, and the like. Specific examples of methacrylic acid esters having an alicyclic structure include isoborneol methacrylate, cyclohexyl methacrylate, dicyclopentyl methacrylate, cyclododecyl methacrylate, methylcyclohexyl methacrylate, trimethylcyclohexyl methacrylate, tert-butylcyclohexyl methacrylate, cyclohexylphenyl methacrylate, and the like.

Specific examples of styrene monomers include, in addition to styrene, alkyl styrenes such as methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, diethyl styrene, triethyl styrene, propyl styrene, butyl styrene, hexyl styrene, heptyl styrene and octyl styrene; halogenated styrenes such as fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene and iodostyrene; and nitrostyrene, acetylstyrene, methoxystyrene, divinylbenzene and the like.

Specific examples of vinyl monomers include fatty acid vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate and vinyl laurate; vinyl halides such as vinyl chloride and vinyl bromide; vinylidene halides such as vinylidene chloride; nitrogen-containing aromatic vinyls such as vinyl pyridine, vinyl pyrrolidone and vinyl carbazole; conjugated diene monomers such as butadiene, isoprene and chloroprene; and acrylonitrile, methacrylonitrile, etc.

Specific examples of the monomer having a plurality of (meth)acryl groups in the molecule include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, and tripropylene glycol di(meth)acrylate, which are monomers having two (meth)acryl groups in the molecule; and trihydroxymethylpropane tri(meth)acrylate, which are monomers having three (meth)acryl groups in the molecule.

The monomers different from the (meth)acrylic acid alkyl ester (P1) represented by formula (III) and the monomer (P2) containing a polar functional group may be used alone or in combination of two or more. When contained in the adhesive, the structural unit derived from the monomer different from the (meth)acrylic acid alkyl ester (P1) represented by formula (III) and the monomer (P2) containing a polar functional group in the acrylic resin (P) is usually 0 to 30 parts by mass relative to 100 parts by mass of the total amount of all structural units constituting the acrylic resin (P).

The resin component constituting the adhesive composition may also include two or more acrylic resins, wherein the acrylic resin includes structural units derived from the (meth)acrylic acid alkyl ester (P1) represented by formula (III) and the monomer (P2) containing a polar functional group. In addition, the acrylic resin (P) may be mixed with an acrylic resin different from the acrylic resin, for example, an acrylic resin having structural units derived from the (meth)acrylic acid alkyl ester (P1) represented by formula (III) but not containing a polar functional group. The acrylic resin (P) including structural units derived from the (meth)acrylic acid alkyl ester (P1) represented by formula (III) and the monomer (P2) containing a polar functional group may be, for example, 70 parts by mass or more relative to 100 parts by mass of the total amount of the acrylic resin contained in the adhesive layer.

The acrylic resin (P) of the copolymer of a monomer mixture of an alkyl (meth)acrylate (P1) represented by formula (III) and a monomer (P2) containing a polar functional group preferably has a weight average molecular weight Mw in the range of 1 to 2 million in terms of polystyrene by gel permeation chromatography (GPC). When the weight average molecular weight in terms of standard polystyrene is within the above range, the adhesion under high temperature and high humidity is improved, the possibility of separation and floating between the conductive layer and the adhesive layer tends to be reduced, and the reworkability tends to be improved. Moreover, even if the size of the polarizing film changes, the adhesive layer can be easily changed along with the size change. For example, when the optical multilayer is attached to the liquid crystal cell, there is no difference between the brightness of the peripheral part and the brightness of the central part of the liquid crystal cell, which tends to suppress white spots and color unevenness.

The molecular weight distribution represented by the ratio Mw/Mn of the weight average molecular weight Mw to the number average molecular weight Mn is preferably in the range of 3 to 7. When the molecular weight distribution Mw/Mn is in the range of 3 to 7, the occurrence of defects such as white spots can be suppressed even when the liquid crystal display panel or liquid crystal display device is exposed to high temperature.

Furthermore, the acrylic resin (P) preferably has a glass transition temperature in the range of -10 to -60°C from the viewpoint of exhibiting adhesiveness. The glass transition temperature of the resin can generally be measured by a differential scanning calorimeter.

The acrylic resin (P) can be produced by various known methods such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, etc. In the production of the acrylic resin (P), a polymerization initiator is usually used. The content of the polymerization initiator is preferably 0.001 to 5 parts by weight relative to 100 parts by weight of all monomers used in the production of the acrylic resin.

The polymerization initiator may be a thermal polymerization initiator, a photopolymerization initiator, etc. Examples of the photopolymerization initiator include 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, etc. Examples of the thermal polymerization initiator include azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), 2,2'-azobis(2-methylacrylate)dimethyl ester and 2,2'-azobis(2-hydroxymethylpropionitrile); lauryl peroxide, 3-butyl hydroperoxide, isopropyl hydroperoxide, diisopropyl peroxydicarbonate, dipropyl peroxydicarbonate, 3-butyl peroxyneodecanoate, 3-butyl peroxypivalate and (3,5,5-trimethylhexanoyl)propionate. Organic peroxides such as iodine peroxide and the like; inorganic peroxides such as potassium persulfate, ammonium persulfate and hydrogen peroxide, etc. In addition, redox initiators using a peroxide and a reducing agent together can also be used as polymerization initiators.

The method for producing the acrylic resin (P) is particularly preferably a solution polymerization method. When a specific example of the solution polymerization method is listed, for example, a method of mixing the desired monomer and organic solvent, adding a thermal polymerization initiator in a nitrogen environment, and stirring at 40 to 90°C, preferably 50 to 80°C, for 3 to 10 hours can be cited. Moreover, in order to control the reaction, the monomer and the thermal polymerization initiator are added continuously or intermittently during the polymerization, and can also be added in a state dissolved in the organic solvent. Here, the organic solvent can be aromatic hydrocarbons such as toluene and xylene; esters such as ethyl acetate and butyl acetate; aliphatic alcohols such as propanol and isopropanol; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, etc.

The adhesive layer contained in the optical laminate of the present invention is preferably formed by using an acrylic resin (P) and a crosslinking agent together. The crosslinking agent is, for example, a compound that reacts with a structural unit in the acrylic resin (P) that is particularly derived from a monomer (P2) containing a polar functional group and crosslinks the acrylic resin. Specifically, for example, isocyanate compounds, epoxy compounds, aziridine compounds, metal chelate compounds, etc. Among them, isocyanate compounds, epoxy compounds, and aziridine compounds have at least two functional groups in the molecule that can react with the polar functional groups in the acrylic resin (P).

Isocyanate compounds are compounds having at least two isocyanate groups (-NCO) in the molecule, and examples thereof include cresyl diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, cresyl diisocyanate, hydrogenated cresyl diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, naphthyl diisocyanate, triphenylmethane triisocyanate, etc. Moreover, adducts obtained by reacting polyols such as glycerol and trihydroxymethylpropane with these isocyanate compounds, or by making the isocyanate compounds into dimers or trimers, etc., can also be used as crosslinking agents for adhesives. Two or more isocyanate compounds can also be mixed and used.

The epoxy compound is a compound having at least two epoxy groups in the molecule, and examples thereof include bisphenol A type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, 1,6-hexanediol diglycidyl ether, trihydroxymethylpropane triglycidyl ether, N,N-diglycidylaniline, N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, etc. Two or more epoxy compounds may be used in combination.

Aziridine compounds are compounds having a skeleton of a three-membered ring consisting of one nitrogen atom and two carbon atoms, called ethylenimine, in the molecule, for example, diphenylmethane-4,4'-bis(1-aziridinecarboxamide), toluene-2,4-bis(1-aziridinecarboxamide), trisethylmelamine, m-phenylenedicarboxylbis-1-(2-methylaziridine), tris-1-aziridinylphosphine oxide, hexamethylene-1,6-bis(1-aziridinecarboxamide), trishydroxymethylpropane tris-β-aziridinylpropionate, tetrahydroxymethylmethane tris-β-aziridinylpropionate, etc.

Examples of metal chelate compounds include compounds in which acetylacetone or ethyl acetylacetate is coordinated to a polyvalent metal such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, or zirconium.

Among the crosslinking agents, it is preferred to use isocyanate compounds, particularly tolyl diisocyanate, tolyl diisocyanate or hexamethylene diisocyanate or adducts of these isocyanate compounds and polyols such as glycerol and trihydroxymethylpropane, dimers or trimers of these isocyanate compounds, or mixtures of these isocyanate compounds. When the monomer (P2) containing a polar functional group has a polar functional group selected from free carboxyl groups, hydroxyl groups, amino groups and epoxy groups, it is particularly preferred to use at least one isocyanate compound as the crosslinking agent. Among them, suitable isocyanate compounds include, for example, tolyl diisocyanate, an adduct of tolyl diisocyanate and a polyol, a dimer of tolyl diisocyanate, and a trimer of tolyl diisocyanate; or hexamethylene diisocyanate, an adduct of hexamethylene diisocyanate and a polyol, a dimer of hexamethylene diisocyanate, and a trimer of hexamethylene diisocyanate.

In the adhesive layer constituting the optical laminate of the present invention, the crosslinking agent is, for example, 0.01 to 10 parts by mass relative to 100 parts by mass of the acrylic resin (P). When the crosslinking agent is within the above range, the durability of the adhesive layer tends to be improved, and the white spots of the liquid crystal display panel tend to become less obvious, so it is preferred.

In the present invention, the adhesive constituting the adhesive layer preferably contains a silane compound, and in particular, the acrylic resin before the crosslinking agent is prepared preferably contains a silane compound in advance. Silane compounds improve adhesion to glass, and by including silane compounds, high adhesion to the display panel can be ensured.

Examples of the silane compound include vinyl trimethoxysilane, vinyl triethoxysilane, vinyl tris(2-methoxyethoxy)silane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-Epoxycyclohexyl)ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-butylpropyltrimethoxysilane, 3-glycyrrhetoxypropyltrimethoxysilane, 3-glycyrrhetoxypropyltriethoxysilane, 3-glycyrrhetoxypropyldimethoxymethylsilane, 3-glycyrrhetoxypropylethoxydimethylsilane, etc. These silane compounds may be used alone or in combination of a plurality of different types.

The silane compound may be a polysiloxane oligomer. When the polysiloxane oligomer is shown in the form of a (monomer)-(monomer) copolymer, the following examples are given.

3-Alkylpropyltrimethoxysilane-tetramethoxysilane copolymer, 3-Alkylpropyltrimethoxysilane-tetraethoxysilane copolymer, 3-Alkylpropyltriethoxysilane-tetramethoxysilane copolymer and 3-Alkylpropyltriethoxysilane-tetraethoxysilane copolymer containing butylene propyl groups; 3-Alkylmethyltrimethoxysilane-tetramethoxysilane copolymer, 3-Alkylpropyltrimethoxysilane-tetraethoxysilane copolymer, 3-Alkylpropyltriethoxysilane-tetramethoxysilane copolymer and 3-Alkylpropyltriethoxysilane-tetraethoxysilane copolymer; 3-methacryloyloxypropyl trimethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropyl trimethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropyl triethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropyl triethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropyl methyl dimethoxysilane 3-methacryloxypropyl methyldimethoxysilane-tetramethoxysilane copolymer, 3-methacryloxypropyl methyldiethoxysilane-tetramethoxysilane copolymer, and 3-methacryloxypropyl methyldiethoxysilane-tetraethoxysilane copolymer, etc., containing methacryloxypropyl groups; 3-acryloxypropyl trimethoxysilane-tetramethoxysilane copolymer, ... 3-Acryloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-Acryloxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-Acryloxypropyltriethoxysilane-tetraethoxysilane copolymer, 3-Acryloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-Acryloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-Acryloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer Silane copolymers and copolymers containing acryloxypropyl such as 3-acryloxypropylmethyldiethoxysilane-tetraethoxysilane copolymers; vinyltrimethoxysilane-tetramethoxysilane copolymers, vinyltrimethoxysilane-tetraethoxysilane copolymers, vinyltriethoxysilane-tetramethoxysilane copolymers, vinyltriethoxysilane-tetraethoxysilane copolymers, vinylmethyldimethoxysilane-tetramethoxysilane copolymers, Copolymers containing vinyl groups such as vinylmethyldimethoxysilane-tetraethoxysilane copolymers, vinylmethyldiethoxysilane-tetramethoxysilane copolymers, and vinylmethyldiethoxysilane-tetraethoxysilane copolymers; 3-aminopropyltrimethoxysilane-tetramethoxysilane copolymers, 3-aminopropyltrimethoxysilane-tetraethoxysilane copolymers, 3-aminopropyltriethoxysilane-tetramethoxysilane copolymers Copolymers containing amino groups such as silane copolymers, 3-aminopropyltriethoxysilane-tetraethoxysilane copolymers, 3-aminopropylmethyldimethoxysilane-tetramethoxysilane copolymers, 3-aminopropylmethyldimethoxysilane-tetraethoxysilane copolymers, 3-aminopropylmethyldiethoxysilane-tetramethoxysilane copolymers, and 3-aminopropylmethyldiethoxysilane-tetraethoxysilane copolymers.

Most of these silane compounds are liquid. The amount of the silane compound in the adhesive is, for example, 0.01 to 10 parts by mass relative to 100 parts by mass of the acrylic resin (P) (or the total amount when two or more types are used). When the amount of the silane compound relative to 100 parts by mass of the acrylic resin (P) is within the above range, it is better because the adhesion between the adhesive layer and the substrate (or liquid crystal cell) is improved, and it is also better because there is a tendency to suppress the silane compound from seeping out of the adhesive layer.

The adhesive layer may also contain an ionic compound. The ionic compound can function as an antistatic agent. In particular, the acrylic resin (P) contains a (meth) acrylic compound containing an aromatic ring as shown in the above formula (IV). When n in the formula (IV) is 2 or more, it is effective in suppressing white spots. By formulating an ionic compound in an adhesive containing an acrylic resin copolymerized with the monomer, a white spot suppression effect can be imparted and good anti-static properties can be imparted. The ionic compound referred to herein is a compound that exists in the form of a combination of a cation and an anion. The cation and anion may be inorganic or organic. From the perspective of compatibility with the acrylic resin (P), it is preferred that at least one of the cation and anion is an ionic compound containing an organic group.

Examples of inorganic cations constituting ionic compounds include alkali metal ions such as lithium cation [Li ⁺ ], sodium cation [Na ⁺ ], potassium cation [K ⁺ ], and cesium cation [Cs ⁺ ]; and alkaline earth metal ions such as palladium cation [Be ²⁺ ], magnesium cation [Mg ²⁺ ], and calcium cation [Ca ²⁺ ]. Among them, from the perspective of metal corrosion resistance, it is better to use lithium cations [Li ⁺ ], potassium cations [K ⁺ ] or sodium cations [Na ⁺ ], and from the perspective of durability, it is more preferable to use potassium cations [K ⁺ ].

Examples of the organic cation constituting the ionic compound include a pyridinium cation represented by the following formula (V), a quaternary ammonium cation represented by the following formula (VI), and the like.

In formula (V), _R5 to _R9 each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and _R10 represents an alkyl group having 1 to 16 carbon atoms. In formula (VI), _R11 represents an alkyl group having 1 to 12 carbon atoms, and _R12 , _R13 and _R14 each independently represent an alkyl group having 6 to 12 carbon atoms.

The pyridinium cation represented by the above formula (V) preferably has a total carbon number of 8 or more, particularly 10 or more, from the viewpoint of compatibility with the acrylic resin (P). Furthermore, the total carbon number is 36 or less, preferably 30 or less. Among the pyridinium cations represented by the formula (V), one of the preferred cations is one in which _R7 bonded to the carbon atom at the 4-position of the pyridine ring is an alkyl group, and _R5 , _R6 , _R8 and _R9 bonded to the other carbon atoms of the pyridine ring are hydrogen atoms.

Specific examples of the pyridinium cation represented by formula (V) include N-methyl-4-hexylpyridinium cation, N-butyl-4-methylpyridinium cation, N-butyl-2,4-diethylpyridinium cation, N-butyl-2-hexylpyridinium cation, N-hexyl-2-butylpyridinium cation, Pyridinium cation, N-hexyl-4-methylpyridinium cation, N-hexyl-4-ethylpyridinium cation, N-hexyl-4-butylpyridinium cation, N-octyl-4-methylpyridinium cation, N-octyl-4-ethylpyridinium cation, N-octylpyridinium cation, etc.

The quaternary ammonium cation represented by the above formula (VI) has a total carbon number of 20 or more, preferably 22 or more, from the viewpoint of compatibility with the acrylic resin (P), and has a total carbon number of 36 or less, preferably 30 or less.

Specific examples of the tetraalkylammonium cation represented by formula (VI) include tetrahexylammonium cation, tetraoctylammonium cation, tributylmethylammonium cation, trihexylmethylammonium cation, trioctylmethylammonium cation, dodecylmethylammonium cation, trihexylethylammonium cation, trioctylethylammonium cation, and the like.

On the other hand, examples of anions constituting ionic compounds include chlorine anions [Cl ^- ], bromine anions [Br ^- ], iodine anions [I ^- ], tetrachloroaluminate anions [AlCl ₄ ^- ], heptachlorodialuminate anions [Al ₂ Cl ₇ ^4- ], tetrafluoroborate anions [BF ₄ ^- ], hexafluorophosphate anions [PF ₆ ^- ], perchlorate anions [ClO ₄ ^- ], nitrate anions [NO ₃ ^- ], acetate anions [CH ₃ COO ^- ], trifluoroacetate anions [CF ₃ COO ^- ], methanesulfonate anions [CH ₃ SO ₃ ^- ], trifluoromethanesulfonate anion [CF ₃ SO ₃ ^- ], bis(trifluoromethanesulfonyl)imide anion [(CF ₃ SO ₂ ) ₂ N ^- ], tris(trifluoromethanesulfonyl)methane anion [(CF ₃ SO ₂ ) ₃ C ^- ], hexafluoroarsenate anion [AsF ₆ ^- ], hexafluoroantimonate anion [SbF ₆ ^- ], hexafluoronitrogen anion [NbF ₆ ^- ], hexafluorotantalum anion [TaF ₆ ^- ], (poly)hydrogen fluoride anion [F(HF) _n ^- ] (n is about 1 to 3), thiocyanate anion [SCN ^- ], dicyanamide anion [(CN) ₂ N ^- ], perfluorobutanesulfonate anion [C ₄ F ₉ SO ₃ ^- ], bis(pentafluoroethanesulfonyl)imide anion [(C ₂ F ₅ SO ₂ ) ₂ N ^- ], perfluorobutyrate anion [C ₃ F ₇ COO ^- ], (trifluoromethanesulfonyl)(trifluoromethanecarbonyl)imide anion [(CF ₃ SO ₂ )(CF ₃ CO)N ^- ], etc.

Specific examples of the ionic compound can be appropriately selected from the above-mentioned combination of cations and anions. Specific examples of the ionic compound of the combination of cations and anions include lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, lithium iodide (lithium iodide), lithium bis(pentafluoroethanesulfonyl)imide, lithium tris(trifluoromethanesulfonyl)methane, sodium bis(trifluoromethanesulfonyl)imide, sodium bis(pentafluoroethanesulfonyl)imide, sodium tris(trifluoromethanesulfonyl)methane, potassium bis(trifluoromethanesulfonyl)imide, and lithium tris(trifluoromethanesulfonyl)methane. Potassium (trifluoromethanesulfonyl) imide, potassium (trifluoromethanesulfonyl) methane, N-methyl-4-hexylpyridinium bis(trifluoromethanesulfonyl) imide, N-butyl-2-methylpyridinium bis(trifluoromethanesulfonyl) imide, N-hexyl-4-methylpyridinium bis(trifluoromethanesulfonyl) imide, N-octyl-4 -Methylpyridinium bis(trifluoromethanesulfonyl)imide, N-methyl-4-hexylpyridinium hexafluorophosphate, N-butyl-2-methylpyridinium hexafluorophosphate, N-hexyl-4-methylpyridinium hexafluorophosphate, N-octyl-4-methylpyridinium hexafluorophosphate, N-methyl-4-hexylpyridinium perchlorate, N-butyl-2-methylpyridinium perchlorate, N-hexyl-4-methylpyridinium perchlorate, N-octyl-4-methylpyridinium perchlorate, tetrahexylammonium bis(trifluoromethanesulfonyl)imide, tributylmethylammonium bis(trifluoromethanesulfonyl)imide, trihexylmethylammonium bis(trifluoromethanesulfonyl)imide, Trioctyl methyl ammonium bis(trifluoromethanesulfonyl)imide, tetrahexyl ammonium hexafluorophosphate, tributyl methyl ammonium hexafluorophosphate, trihexyl methyl ammonium hexafluorophosphate, trioctyl methyl ammonium hexafluorophosphate, tetrahexyl ammonium perchlorate, tributyl methyl ammonium perchlorate, trihexyl methyl ammonium perchlorate, trioctyl methyl ammonium perchlorate, etc.

The ionic compounds may be used alone or in combination. When the ionic compound is contained, its amount is, for example, 0.1 to 10 parts by mass relative to 100 parts by mass of the acrylic resin (P).

In the present invention, the adhesive layer may further contain a crosslinking catalyst, a weathering stabilizer, a tackifier, a plasticizer, a softener, a dye, a pigment, an inorganic filler, a resin other than an acrylic resin, etc. The adhesive layer may be formed by mixing a UV-curable compound such as a multifunctional acrylate and a photoinitiator, and then hardening the adhesive layer by irradiating UV rays, so as to form a harder adhesive layer. This is to embody a second crosslinking structure in the adhesive, and improve the durability during heat resistance tests, etc. Furthermore, when a crosslinking agent and a crosslinking catalyst are used together with an adhesive, the adhesive layer can be cured in a short time, and in the obtained optical laminate, the occurrence of floating and peeling between the adhesive layer and the first hardened layer or the first protective film can be suppressed, and the occurrence of bubbles in the adhesive layer can be suppressed, and the reworkability is also improved.

Examples of crosslinking catalysts include amine compounds such as hexamethylenediamine, ethylenediamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethylenetetramine, isophoronediamine, trimethylenediamine, polyamine resins, and melamine resins. When the adhesive is formulated with amine compounds as crosslinking catalysts, isocyanate compounds are suitable as crosslinking agents.

Furthermore, the adhesive layer may contain microparticles to form a light scattering adhesive layer. In addition, antioxidants, ultraviolet absorbers, etc. may be formulated in the adhesive layer. Examples of ultraviolet absorbers include salicylate compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, and nickel fluoride salt compounds.

The adhesive layer can be provided by, for example, forming the above-mentioned adhesive into an organic solvent solution, applying it to the film or layer to be laminated (such as a polarizing film, etc.) by a slit coater, a gravure coater, etc., and drying it. In addition, it can also be provided by transferring a sheet adhesive formed on a plastic film (called a separator film) subjected to a release treatment to the film or layer to be laminated. The thickness of the adhesive layer is not particularly limited, and is preferably in the range of 2 to 40 μm, more preferably in the range of 5 to 35 μm, and even more preferably in the range of 10 to 30 μm.

The adhesive layer preferably has a storage modulus of 0.10 to 5.0 MPa at 23 to 80°C, and more preferably 0.15 to 1.0 MPa. When the storage modulus at 23 to 80°C is 0.10 MPa or more, it is preferred because white spots caused by shrinkage of the optical laminate when the liquid crystal display panel including the optical laminate is exposed to high temperature, etc. can be suppressed. Moreover, when it is 5 MPa or less, it is preferred because it is less likely to cause a decrease in durability due to a decrease in adhesion. Here, "displaying a storage modulus of 0.10 to 5.0 MPa at 23 to 80°C" means that at any temperature in the range, the storage modulus is a value within the above range. Since the storage modulus generally decreases as the temperature rises, if either the storage modulus at 23°C or 80°C is within the above range, the adhesive layer can exhibit the storage modulus within the above range at the temperature within the range. The storage modulus of the adhesive layer can be measured by a commercially available viscoelasticity measuring device, such as the "SYNAMIC ANALYZER RDA II" viscoelasticity measuring device manufactured by REOMETRIC.

[Conductive layer]

The conductive layer included in the optical laminate of the present invention may be, for example, a conductive transparent metal oxide layer or a metal wiring layer. Such a conductive layer may be, for example, a layer containing at least one metal element selected from aluminum, copper, silver, iron, tin, zinc, platinum, nickel, molybdenum, chromium, tungsten, lead, titanium, palladium, indium, and alloys containing two or more of these. Among these, the conductive layer is preferably a layer containing at least one metal element selected from aluminum, copper, silver, and gold from the perspective of conductivity, and is more preferably a layer containing aluminum from the perspective of conductivity and cost. Furthermore, in the case of a layer containing copper, a blackening treatment may be performed from the viewpoint of preventing light reflection. The so-called blackening treatment is to oxidize the surface of the conductive layer to precipitate Cu ₂ O or CuO. The conductive layer may be a layer containing, for example, metallic silver, ITO (tin-doped indium oxide), graphite, zinc oxide, or AZO (aluminum-doped zinc oxide).

The conductive layer (conductive layer 4 in FIG. 1 and FIG. 2) is, for example, disposed on a substrate (substrate X in FIG. 1 and FIG. 2). The method of forming the conductive layer on the substrate may be, for example, a sputtering method. The substrate may be a transparent substrate constituting a liquid crystal cell included in the touch input element, or may be a glass substrate. The transparent substrate may be formed of polyethylene terephthalate, polycarbonate, polymethacrylate, polyethylene naphthalate, polyether sulfone, cyclic olefin copolymer, triacetyl cellulose, polyvinyl alcohol, polyimide, polystyrene, biaxially stretched polystyrene, etc. The glass substrate may be formed of, for example, sodium calcium glass, low-alkali glass, alkali-free glass, etc. The conductive layer may be formed on the entire surface of the substrate, or may be formed on a portion thereof.

Examples of the conductive transparent metal oxide layer include transparent electrode layers such as ITO (tin-doped indium oxide) and AZO (aluminum-doped zinc oxide).

The metal wiring layer may be, for example, a metal mesh of a metal wiring layer of fine wires, metal nanoparticles, or a layer of metal nanowires added to a binder. Furthermore, the so-called metal mesh refers to a two-dimensional mesh structure formed by metal wiring. The shape of the openings of the metal mesh (openings or meshes between wirings) is not particularly limited, and may be, for example, polygonal (triangular, quadrilateral, pentagonal, hexagonal, etc.), circular, elliptical, or amorphous, and each opening may be the same or different. In a preferred embodiment, the shapes of the openings of the metal mesh are the same shape, and are square or rectangular.

When the conductive layer is a metal wiring layer (especially a metal mesh), the metal wiring is arranged at a specified interval in the vertical and horizontal directions of the plane on the substrate X. At this time, the aforementioned opening can be filled with resin (adhesive, etc.), or the metal wiring can be buried in the resin (adhesive, etc.). Furthermore, when using resin, etc., the conductive layer (conductive layer 4) can be composed of both metal wiring and resin (adhesive).

The line width of metal wiring (especially metal mesh) is usually 10 μm or less, preferably 5 μm or less, more preferably 3 μm or less, and usually 0.1 μm or more, preferably 0.5 μm or more, more preferably 1 μm or more. The line width of the metal wiring layer can be a combination of the upper and lower limits, preferably 0.5 to 5 μm, more preferably 1 to 3 μm.

The thickness of the conductive layer (conductive transparent metal oxide layer or metal wiring layer) is not particularly limited, and is usually 10 μm or less, preferably 3 μm or less, more preferably 1 μm or less, and particularly preferably 0.5 μm or less, and is usually 0.01 μm or more, preferably 0.05 μm or more, and more preferably 0.1 μm or more. The thickness of the conductive layer may be a combination of the upper and lower limits, preferably 0.01 to 3 μm, and more preferably 0.05 to 1 μm. Furthermore, when the conductive layer is a metal wiring layer, and the metal wiring layer is composed of both a resin (adhesive, etc.) and metal wiring, the thickness of the conductive layer is the thickness including the resin.

The preparation method of the conductive layer is not particularly limited. It can be a laminate of metal foil, or can be formed by vacuum evaporation, sputtering, wet coating, ion plating, inkjet printing, gravure printing, electrolytic plating, or electroless plating. Preferably, it is a conductive layer formed by sputtering, inkjet printing, or gravure printing, and more preferably, it is a conductive layer formed by sputtering.

The conductive layer (eg, metal mesh) may also have functions such as generating a signal when the transparent substrate is touched in a touch panel and transmitting the touch coordinates to an integrated circuit.

The optical laminate of the present invention is obtained by laminating (or stacking) the laminate of the first cured layer and the adhesive layer in sequence on one side of the polarizing film to a conductive layer formed on a substrate.

An optical laminate having a conductive layer (e.g., a conductive transparent metal oxide layer, a metal wiring layer, etc.) is useful because it can be used in a touch input type liquid crystal display device having a touch panel function, etc. However, the dichroic dye (iodine) contained in the polarizing film migrates to the conductive layer, and the conductive layer is easily corroded. In particular, when a metal wiring layer such as a metal mesh is used, the conductive layer becomes more susceptible to corrosion due to the narrow line width. However, the optical laminate of the present invention can effectively suppress the migration of the dichroic dye to the conductive layer because it has a first hardening layer, and can effectively prevent the corrosion of the conductive layer.

[Polarizing film]

The polarizing film constituting the optical laminate of the present invention is a film having the function of extracting linear polarized light from incident natural light. In the present invention, the film is a polyvinyl alcohol resin film containing a dichroic pigment, preferably iodine, and adsorbed and aligned. The polyvinyl alcohol resin constituting the polyvinyl alcohol resin film can be a polyvinyl acetate resin that has been saponified. The polyvinyl acetate resin is a copolymer of vinyl acetate and other monomers that can be copolymerized therewith (e.g., ethylene-vinyl acetate copolymer, etc.), in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate. Other monomers that can be copolymerized with vinyl acetate include, for example, unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

The saponification degree of the polyvinyl alcohol resin is usually 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol resin may be modified, for example, polyvinyl formal, polyvinyl acetaldehyde and polyvinyl butyral modified with aldehydes. Moreover, the degree of polymerization of the polyvinyl alcohol resin is usually 1000 to 10000, preferably 1500 to 5000.

The film made of such a polyvinyl alcohol resin can be used as a polarizer film. The method of making a polyvinyl alcohol resin film is not particularly limited, and the film can be made by a conventionally known method. The film thickness of the film made of the polyvinyl alcohol resin is not particularly limited, but when considering the ease of stretching, it is, for example, 10 to 150 μm, preferably 15 to 100 μm, and more preferably 20 to 80 μm.

The polarizing film is usually produced by: stretching the polyvinyl alcohol resin film in one axis; dyeing the polyvinyl alcohol resin film with a dichroic dye to adsorb the dichroic dye; treating the polyvinyl alcohol resin film adsorbed with the dichroic dye with a boric acid aqueous solution; and washing the film with water after the boric acid aqueous solution treatment.

The one-axis stretching of the polyvinyl alcohol resin film can be performed before dyeing with a dichroic pigment, at the same time as dyeing, or after dyeing. When the one-axis stretching is performed after dyeing, the one-axis stretching can be performed before boric acid treatment or during boric acid treatment. The one-axis stretching can also be performed in multiple stages. During the one-axis stretching, the one-axis stretching can be performed between rollers with different rotation speeds, or a hot roller can be used for the one-axis stretching. Moreover, the one-axis stretching can be a dry stretching performed in the atmosphere, or a wet stretching performed in a state where the polyvinyl alcohol resin film is expanded using a solvent. From the viewpoint of suppressing deformation of the polarizing film, the stretching ratio is preferably 8 times or less, more preferably 7.5 times or less, and even more preferably 7 times or less. Furthermore, the stretching ratio is preferably 4.5 times or more from the viewpoint of exhibiting the function as a polarizing film.

In the present invention, a method of dyeing a polyvinyl alcohol resin film by immersing it in an aqueous solution containing iodine and potassium iodide is generally adopted. The content of iodine in the aqueous solution is generally 0.01 to 1 mass part per 100 mass parts of water, and the content of potassium iodide is generally 0.5 to 20 mass parts per 100 mass parts of water. The temperature of the aqueous solution used for dyeing is generally 20 to 40°C, and the immersion time (dyeing time) of the aqueous solution is generally 20 to 1800 seconds.

The boric acid treatment after iodine dyeing is carried out by immersing the dyed polyvinyl alcohol-based resin film in an aqueous solution containing boric acid. The amount of boric acid in the aqueous solution containing boric acid is generally 2 to 15 parts by mass, preferably 5 to 12 parts by mass per 100 parts by mass of water. In the present invention, the aqueous solution containing boric acid preferably contains potassium iodide. The amount of potassium iodide in the aqueous solution containing boric acid is generally 0.1 to 15 parts by mass, preferably 5 to 12 parts by mass per 100 parts by mass of water. The immersion time in the aqueous solution containing boric acid is generally 60 to 1200 seconds, preferably 150 to 600 seconds, and more preferably 200 to 400 seconds. The temperature of the aqueous solution containing boric acid is usually 50°C or higher, preferably 50 to 85°C, and more preferably 60 to 80°C.

The polyvinyl alcohol-based resin film after the boric acid treatment is usually subjected to a water washing treatment. The water washing treatment is performed, for example, by immersing the polyvinyl alcohol-based resin film treated with boric acid in water. The temperature of the water in the water washing treatment is usually 5 to 40°C, and the immersion time is usually 1 to 120 seconds. After water washing, a drying treatment is performed to obtain a polarizing film. The drying treatment can be performed using a hot air dryer or a far infrared heater. The temperature of the drying treatment is usually 30 to 100°C, preferably 40 to 95°C, and more preferably 50 to 90°C. The time of the drying treatment is usually 60 to 600 seconds, and preferably 120 to 600 seconds.

In this way, the polyvinyl alcohol resin film is subjected to uniaxial stretching, dichroic dyeing, preferably iodine dyeing, and boric acid treatment to obtain a polarizing film. The thickness of the polarizing film can be, for example, 5 to 40 μm.

[Second hardened layer]

The optical laminate of the present invention may also have a second cured layer composed of a cured product of a curable composition on the surface of the polarizing film opposite to the first cured layer. The curable composition constituting the second cured layer may be appropriately selected according to the adhesion between the polarizing film and the second protective film, and may be a composition included in the range of the curable composition constituting the first cured layer, or may be a photocurable adhesive known in the art. When a composition included in the range of the curable composition constituting the first cured layer is used, a curable composition having the same composition as that of the curable composition of the first cured layer constituting the optical laminate may be used for the second cured layer, or a curable composition having a different composition may be used for the second cured layer.

Examples of known photocurable adhesives in the art include a mixture of a photocurable epoxy resin and a photocationic polymerization initiator, a mixture of a photocurable acrylic resin and a photoradical polymerization initiator, etc. The curable composition for forming the cured product constituting the second cured product layer may be a curable adhesive containing a photocurable component and a photocationic polymerization initiator as described in International Publication No. 2014/129368.

The second cured layer can be formed, for example, by applying a curable composition constituting the second cured layer on the surface of the optical laminate opposite to the surface on which the first cured layer is deposited, by a known method, and curing the curable composition. The curable composition constituting the second cured layer can be applied in the same manner as the curable composition (1).

When the curable composition constituting the second cured layer is a photocurable composition or a known photocurable adhesive, the curable composition or curable adhesive is cured by irradiating with active energy rays. The light source of the active energy rays is not particularly limited, but preferably has an active energy ray with a luminescence distribution of a wavelength of 400nm or less, and specifically, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, metal halide lamps, etc. are preferred.

The light irradiation intensity of the curable composition constituting the second cured layer can be appropriately selected according to the composition of the curable composition, and is not particularly limited. However, the irradiation intensity in the wavelength region effective for activating the polymerization initiator is preferably 0.1 to 1000 mW/cm ² . The light irradiation time of the curable composition constituting the second cured layer can be appropriately selected according to the curable composition to be cured, and the accumulated light quantity expressed as the product of the above irradiation intensity and the irradiation time is preferably set to 10 to 5000 mJ/cm ² . Furthermore, when the curable composition is cured by irradiating the active energy rays, it is preferred to perform the curing under the condition that the various functions of the optical laminate, such as the polarization degree, transmittance and hue of the polarizing film and the transparency of the various films constituting the protective film and the optical layer, are not reduced. The thickness of the second cured layer is not particularly limited, but is usually 0.1 to 10 μm.

[Protective film]

In one embodiment, the optical laminate of the present invention has a first protective film (7 shown in FIG. 2) laminated on one side of the polarizing film via a first cured layer. In addition, in one embodiment, the optical laminate of the present invention has a second protective film laminated on the other side (the side opposite to the first cured layer) of the polarizing film via a second cured layer. From the viewpoint of preventing the contraction and expansion of the polarizing film and preventing the degradation of the polarizing film due to temperature, humidity, ultraviolet rays, etc., in one embodiment, the optical laminate of the present invention has the first protective film. On the other hand, from the perspective of reducing the thickness of the optical laminate, in one embodiment, the optical laminate of the present invention does not include the first protective film. The first cured layer of the present invention replaces the protective film and helps prevent the degradation of the polarizing film. From the perspective of achieving a good balance between preventing the degradation of the polarizing film and reducing the thickness of the optical laminate, it is preferred that the optical laminate of the present invention does not include the first protective film.

The material forming the protective film is preferably one having excellent transparency, mechanical strength, thermal stability, moisture shielding property, isotropic properties, etc. Examples include polyester polymers such as polyethylene terephthalate and polyethylene naphthalate; cellulose polymers such as diacetyl cellulose and triacetyl cellulose; acrylic polymers such as polymethyl methacrylate; styrene polymers such as polystyrene and acrylonitrile/styrene copolymer (AS resin); polycarbonate polymers, etc. In addition, polyethylene, polypropylene, cyclic or norbornene-structured polyolefins; polyolefin polymers such as ethylene/propylene copolymers; vinyl chloride polymers, nylon, amide polymers such as aromatic polyamides; imide polymers, sulfonate polymers, polyethersulfonate polymers, polyetheretherketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, arylate polymers, polyoxymethylene polymers, epoxy polymers, or mixtures of the above polymers are examples of polymers forming the protective film. The protective film can also be formed as a cured layer obtained by a thermosetting or ultraviolet curing resin such as an acrylic, amine, acrylic amine, epoxy, or silicone resin. Among them, those having a hydroxyl group reactive with an isocyanate crosslinking agent are preferred, and cellulose is particularly preferred.

In the optical laminate of the present invention, the first protective film and the second protective film may be made of the same material or different materials.

The moisture permeability of the second protective film is preferably 1200g/(m ² ‧24 hours) or less, more preferably 800g/(m ² ‧24 hours) or less, even more preferably 600g/(m 2 ‧24 hours) or less, particularly preferably 400g/(m ² ‧24 hours) or less, and most preferably 200g/(m ² ‧24 hours) or less at a temperature of 23 ^° C and a relative humidity of 55%. When the moisture permeability of the second protective film is below the above value, it can prevent the intrusion of moisture from the outside under high temperature and high humidity, and can prevent the accelerated migration of the dichroic dye (iodine) contained in the polarizing film, so that the corrosion of the conductive layer and the degradation of the optical characteristics can be more effectively prevented. On the other hand, since the optical laminate of the present invention has the first cured layer, even if the second protective film does not satisfy the above-mentioned moisture permeability, the migration of the dichroic dye (iodine) contained in the polarizing film can be suppressed, and the degradation of the conductive layer and the degradation of the optical characteristics can be prevented.

The thickness of the protective film is not particularly limited, and either the first protective film or the second protective film is usually 5 to 500 μm, preferably 1 to 300 μm, more preferably 5 to 200 μm, and even more preferably 10 to 100 μm. Furthermore, the protective film may also be composed of a protective film with an additional optical compensation function.

In the optical laminate of the present invention, the first cured material layer can effectively suppress the migration of the dichroic dye from the polarizing film to the adhesive layer and the migration of the ionic compound from the adhesive layer to the polarizing film, so the selection range of the material of the first protective film constituting the optical laminate is wide. That is, it is not necessary to use a protective film that is not easy to pass through the ionic compound, and the optical laminate can be constructed using a protective film of a generally inexpensive structure that is easy to pass through the ionic compound, thereby reducing the production cost, etc. The optical laminate of the present invention is also advantageous from the industrial point of view.

The optical laminate of the present invention shown in FIG. 1 and FIG. 2 has the first hardened layer directly laminated on the polarizing film, but a primer layer may also be provided between the polarizing film and the first hardened layer or between the first hardened layer and the adhesive layer. The material forming the primer layer may include various polymers such as amine oligomers, metal oxide sols, silicon oxide sols, etc. The thickness of the primer layer is thinner than the protective film, for example, 0.01 to 3 μm, preferably 0.1 to 2 μm, and more preferably 0.5 to 1 μm.

Furthermore, the optical laminate of the present invention may include a protective film between the polarizing film and the first cured layer via an adhesive layer. The protective film may be, for example, the same protective film as the first protective film or the second protective film exemplified above. The thickness of the protective film is also the same as the first protective film or the second protective film, usually 5 to 500 μm.

The optical laminate of the present invention can effectively prevent the migration of the dichroic dye even if there is no protective film between the polarizing film and the first cured layer. Therefore, the optical laminate of the present invention is preferably formed in such a manner that the first cured layer is directly formed on the polarizing film, or the first cured layer is formed on the polarizing film via a primer layer, or the adhesive layer is formed on the first cured layer via a primer layer.

The optical laminate of the present invention can be further laminated with optical layers such as phase difference film, viewing angle compensation film and brightness enhancement film as needed. The optical layers in the optical laminate of the present invention can be formed using materials known in the art.

The optical laminate of the present invention can be manufactured by a known method. For example, a curable composition is coated on a second protective film to form a second curable composition layer, and a polarizing film is bonded to the second curable composition layer to manufacture the laminate. In the case of an optical laminate that does not include a first protective film, a curable composition (1) is coated on a release film to form a first curable composition layer, and the polarizing film side of the laminate is bonded to the coated surface. Then, active energy rays such as ultraviolet rays and electron rays are irradiated to cure the second curable composition layer and the first curable composition layer to form the second cured layer and the first cured layer. Then, the release film is peeled off to form an adhesive layer on the first cured layer. Then, for example, an adhesive layer is bonded to the conductive layer deposited on the substrate. On the other hand, in the case of an optical laminate including a first protective film, a curable composition (1) is coated on the protective film to form a first curable composition layer, and the polarizing film side of the laminate is bonded to the coated surface, and then the first curable composition layer is cured by irradiating with active energy rays such as ultraviolet rays and electron beams to form a first cured layer, and then an adhesive layer is formed on the first protective film. Then, for example, an adhesive layer is bonded to the conductive layer deposited on the substrate.

From the viewpoint of reducing the uneven thickness when applying the curable composition and thinning the optical laminate, a laminate can be formed by using a separator (peelable film) as described above. For example, a laminate composed of a polarizing film and a first curing material layer can be formed by laminating a separator (peelable film) on one side of the polarizing film via the first curing material layer, curing the first curable composition layer by active energy rays, etc., and then peeling off the separator (peelable film).

The present invention is an optical laminate having the above-mentioned structure, that is, an optical laminate having a first cured material layer, an adhesive layer, and a conductive layer formed of a cured material of a curable composition containing a polymerizable compound, which are sequentially laminated on one side of a polarizing film containing a dichroic dye in a polyvinyl alcohol-based resin (in one embodiment, the optical laminate shown in FIGS. 1 and 2 ); wherein the polymerizable compound comprises an oxycyclobutane compound having two or more oxycyclobutane groups, and the content of the oxycyclobutane compound is 40 parts by mass or more relative to 100 parts by mass of the total amount of all polymerizable compounds contained in the curable composition. When an oxycyclobutane compound having two or more oxycyclobutane groups is contained in a specified amount or more, a first cured layer having a high crosslinking density and being dense can be formed, so that the migration of the dichroic dye (iodine) contained in the polarizing film to the first cured layer can be effectively suppressed, and the corrosion of the conductive layer and the reduction of the optical performance due to the dichroic dye (iodine) can be effectively prevented. Furthermore, with respect to such an optical laminate, the absorbance increase rate of the first cured layer may be 30% or less. In a preferred embodiment, the cyclohexane compound having two or more cyclohexane groups is the cyclohexane compound (A) mentioned above, and the components and contents (including preferred components and contents) of the curable composition of the cured product forming the first cured product layer are also the same as above. Furthermore, the polarizing film, adhesive layer and conductive layer included in the optical laminate are also the same as above.

In the present invention, an optical laminate including a first cured layer composed of a cured product of a curable composition containing a polymerizable compound, an adhesive layer, and a conductive layer are sequentially laminated on one side of a polarizing film containing a dichroic dye in a polyvinyl alcohol-based resin. The optical laminate has a water contact angle of 90° or more in the first cured layer. Due to the good hydrophobicity of the first cured layer, the migration of the dichroic dye (iodine) can be effectively suppressed even in a high temperature and high humidity environment where the migration of the dichroic dye (iodine) is significant, and the corrosion of the conductive layer and the reduction of the optical performance can be effectively prevented.

In the present invention, the water contact angle of the first hardened layer is, for example, 90° or more, preferably 95° or more, and more preferably 100° or more. When the water contact angle is greater than the above value, even in a high temperature and high humidity environment, the migration of the dichroic dye to the first hardened layer is effectively suppressed, and corrosion of the conductive layer and reduction in optical performance can be effectively prevented.

In the present invention, an optical laminate comprising a first cured layer composed of a cured product of a curable composition containing a polymerizable compound, an adhesive layer, and a conductive layer are sequentially laminated on one side of a polarizing film containing a dichroic dye in a polyvinyl alcohol-based resin. The first cured layer has a storage elastic modulus of 1500 MPa or more at 30°C. Due to a high cross-linking density, the optical laminate has a high barrier property against the dichroic dye (iodine), and can effectively inhibit the migration of the dichroic dye to the first cured layer, thereby effectively preventing corrosion of the conductive layer and degradation of the optical performance.

The storage elastic modulus of the first cured layer at 30° C. is, for example, 1500 to 3500 MPa, preferably 1800 to 3500 MPa, more preferably 2000 to 3500 MPa, and even more preferably 2500 to 3500 MPa. When the elastic modulus is equal to or greater than the above lower limit, migration of the dichroic dye to the first cured layer can be effectively suppressed, and corrosion of the conductive layer and reduction in optical performance can be effectively prevented.

In the present invention, an optical laminate including a first cured layer composed of a cured product of a curable composition containing a polymerizable compound, an adhesive layer, and a conductive layer are sequentially laminated on one side of a polarizing film containing a dichroic dye in a polyvinyl alcohol-based resin. The optical laminate has a glass transition temperature of 90° C. or higher in the first cured layer. Due to a high cross-linking density, the optical laminate has a high barrier property against the dichroic dye (iodine), and can effectively suppress the migration of the dichroic dye to the first cured layer, thereby effectively preventing corrosion of the conductive layer and degradation of the optical performance.

The glass transition temperature of the first cured layer is, for example, 90 to 180° C., preferably 100 to 180° C., more preferably 120 to 180° C., and even more preferably 150 to 180° C. When the glass transition temperature is equal to or higher than the above lower limit, migration of the dichroic dye to the first cured layer can be effectively suppressed, and corrosion of the conductive layer and reduction in optical performance can be effectively prevented.

[Implementation example]

The present invention is described in more detail below by way of examples, but the present invention is not limited to these examples. Furthermore, "%" and "parts" in the examples and comparative examples, unless otherwise specified, represent "mass %" and "mass parts", respectively.

[Implementation Example 1] 1. Preparation of the curable composition (I) constituting the first curing layer

According to the composition shown in Table 1 below, the components were mixed to prepare the curable compositions (I) of Production Examples 1 to 31.

2. Evaluation of the absorbance increase rate of the first cured layer (iodine ion absorption evaluation)

The curable composition (I) of Production Example 1 was applied to one side of a 50 μm thick cycloolefin film [trade name "ZEONOR", manufactured by ZEON Co., Ltd., Japan] using a bar coater so that the film thickness after curing was about 30 μm. A 50 μm thick cycloolefin film [trade name "ZEONOR", manufactured by ZEON Co., Ltd., Japan] was bonded to the coated surface to produce a laminate. The curable composition (I) was cured by irradiating ultraviolet rays from the cycloolefin film side of the laminate using an ultraviolet irradiation device equipped with a belt conveyor [the lamp used was a "D bulb" manufactured by Fusion UV system] so that the accumulated light amount from 280nm to 320nm became 1000mJ/ ^cm2 , thereby obtaining a laminate having cycloolefin films laminated on both sides of the first cured layer. The cycloolefin films on both sides of the obtained laminate were peeled off, and the cured product of the curable composition (I) (first cured layer) was separated alone and used as a sample for evaluation.

The sample for evaluation was measured for absorbance at 360 nm using an ultraviolet-visible spectrophotometer ("UV2450" manufactured by Shimadzu Corporation). This absorbance was taken as the absorbance before immersion.

Then, the evaluation samples were immersed in a 50% potassium iodide aqueous solution for 100 hours in an atmosphere at a temperature of 23°C and a relative humidity of 60%. The evaluation samples were taken out, the surface was wiped with pure water, and the absorbance at 360 nm was measured using an ultraviolet-visible spectrophotometer ("UV2450" manufactured by Shimadzu Corporation). This absorbance was taken as the absorbance after immersion.

The absorbance increase rate (%) expressed by the following formula was calculated using the obtained absorbance. The results are shown in Table 1. In addition, the absorbance increase rate of each cured layer formed by the curable composition (I) of Production Examples 2 to 31 was determined in the same manner. The results are shown in Table 1.

Absorbance increase rate (%) = (absorbance after immersion (360nm) - absorbance before immersion (360nm)) / absorbance before immersion (360nm) × 100 (1)

The components in Table 1 are shown below.

〈Aliphatic epoxide (B2)〉

B2-1: 3,4-Epoxycyclohexylcarboxylic acid 3,4-Epoxycyclohexylmethyl ester ("CELLOXIDE 2021P" (trade name), manufactured by Daicel Chemical Co., Ltd.)

B2-2: 1,2-epoxy-4-(2-oxoethylene)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol ("EHPE3150" (trade name), manufactured by Daicel Chemical Co., Ltd.)

〈Aliphatic epoxide (B1)〉

B1-1: 1,4-Butanediol diglycidyl ether ("EX-214" (trade name), manufactured by Nagase Chemtex Co., Ltd.)

B1-2: Cyclohexanedimethanol diglycidyl ether ("EX-216" (trade name), manufactured by Nagase Chemtex Co., Ltd.)

B1-3: Cyclohexanedimethanol diglycidyl ether ("EX-411" (trade name), manufactured by Nagase Chemtex Co., Ltd.)

〈Aromatic Epoxides (B3)〉

B3-1: Cresol diglycidyl ether ("EX-201" (trade name), manufactured by Nagase Chemtex Co., Ltd.)

B3-2: Bisphenol A epoxy resin ("jER828EL" (trade name), manufactured by Mitsubishi Chemical Co., Ltd.)

B3-3: 2-[4-(2,3-epoxypropoxy)phenyl]-2-[4-[11-bis[4-(2,3-epoxypropoxy)phenyl]ethyl]phenyl]propane ("TECHMORE VG3101L" (trade name), manufactured by Printech Co., Ltd.)

〈Oxycyclobutane compound (A)〉

A1-1: Bis(3-ethyl-3-oxocyclobutane) ether ("OXT-221" (trade name), manufactured by Toa Gosei Co., Ltd.)

A1-2: Xylylene dicyclobutane ("OXT-121" (trade name), manufactured by Toa Gosei Co., Ltd.)

〈Oxycyclobutane compound (a)〉

a1-1: 2-ethylhexyloxycyclobutane ("OXT-212" (trade name), manufactured by Toagosei Co., Ltd., a compound having one oxycyclobutane group)

a1-2: 3-ethyl-3-hydroxymethyl cyclohexane ("OXT-101" (trade name), manufactured by Toagosei Co., Ltd., a compound having one cyclohexane group)

〈Acrylic acid compounds〉

P1-1: tricyclodecanedimethanol diacrylate ("A-DCP" (trade name), manufactured by Shin-Nakamura Chemical Co., Ltd.)

P1-2: Diacrylate of the acetal compound of hydroxypivaldehyde and trihydroxymethylpropane ("A-DOG" (trade name), manufactured by Shin-Nakamura Chemical Co., Ltd.)

〈Polymerization initiator〉

G1-1: Photocatalytic polymerization initiator: 50% solution of triarylsulfonium hexafluorophosphate in propylene carbonate ("CPI-100P" (trade name), manufactured by SANAPRO Co., Ltd.)

G1-2: Photoradical polymerization initiator: 2-Hydroxy-2-methyl-1-phenylpropane-1-one ("DAROCURE 1173" (trade name), manufactured by BASF Japan Co., Ltd.)

〈Leveling agent〉

S1-1: Silicone leveling agent ("SH710" (trade name), manufactured by Toray and Dow Corning Co., Ltd.)

3. Production of polarizing film

A 20 μm thick polyvinyl alcohol film (Kuraray Co., Ltd., "Kuraray Poval KL318" (trade name), carboxyl-modified polyvinyl alcohol, average degree of polymerization of about 2,400, saponification degree of 99.9 mol% or more) was stretched to about 5 times in one axis by dry stretching, and then immersed in 60°C pure water for 1 minute while maintaining tension, and then immersed in an aqueous solution of iodine/potassium iodide/water at a mass ratio of 0.05/5/100 at 28°C for 60 seconds. Then, it was immersed in an aqueous solution of potassium iodide/boric acid/water at a mass ratio of 8.5/8.5/100 at 72°C for 300 seconds. The film was then washed with pure water at 26° C. for 20 seconds and dried at 65° C. to obtain a polarizing film (1) having a thickness of 7 μm and iodine adsorbed and aligned on the polyvinyl alcohol film.

4. Preparation of water-based adhesives

3.0 parts by mass of polyvinyl alcohol film (Kuraray Co., Ltd., "Kuraray Poval KL318" (trade name), carboxyl-modified polyvinyl alcohol) and 1.5 parts by mass of water-soluble polyamide epoxy resin (Sumika Chemtex Co., Ltd., "SUMIREZ RESIN 650" (trade name), working liquid with a solid content concentration of 30%) were mixed with 100 parts by mass of pure water to prepare a water-based adhesive (1). The parts by mass of "SUMIREZ RESIN 650" represent the mass of the solid content.

5. Preparation of laminate (1)

A water-based adhesive (1) was applied to one side of a polarizing film (1), and a triacetyl cellulose film (Toppan (Co., Ltd.) TOMOEGAWA Optical Film, "25KCHC-TC" (trade name), thickness 32 μm) with a hard coating was subjected to saponification treatment, and then the surface not subjected to the hard coating was attached to the polarizing film via the water-based adhesive (1). The film was dried at 60°C for 6 minutes to prepare a laminate (1) having a protective film on one side.

6. Preparation of laminated body (2)

A curable composition (I) was applied to one side of a 50 μm thick cycloolefin film [trade name "ZEONOR", manufactured by ZEON Co., Ltd., Japan] using a bar coater so that the film thickness after curing was about 3 μm. The polarizing film side of the laminate (1) was bonded to the coated surface to produce a laminate. From the cycloolefin film side of the laminate, ultraviolet rays were irradiated using an ultraviolet irradiation device with a belt conveyor [the lamp used was a "D bulb" manufactured by Fusion UV System] so that the accumulated light amount at 280 nm to 320 nm was 200 mJ/ ^cm2 , and the curable composition (I) was cured, and then the cycloolefin film was peeled off. A laminate (2) consisting of a protective film/aqueous adhesive/polarizing film/a cured product (first cured product layer) of a curable composition (I) is produced.

7. Preparation of laminated body (3)

An organic solvent solution of an acrylic adhesive was prepared and applied to a release-treated surface of a polyethylene terephthalate film having a thickness of 38 μm [manufactured by Lintech Co., Ltd., "SP-PLR382050" (trade name), referred to as a release film], and applied to a thickness of 20 μm after drying using a slit coater, and dried to produce a sheet-shaped adhesive with a release film. Then, the first cured material layer of the laminate (2) is laminated with the surface (adhesive surface) opposite to the peeling film of the obtained sheet-like adhesive by a laminating machine, and then aged for 7 days at a temperature of 23°C and a relative humidity of 65% to obtain a laminate (3) provided with an adhesive layer. The laminate has a structure in which the peeling film is laminated on the adhesive layer.

Acrylic adhesives contain the following.

〈Matrix polymer〉

Copolymer of butyl acrylate, methyl acrylate, acrylic acid and hydroxyethyl acrylate

〈Isocyanate crosslinking agent〉

Ethyl acetate solution of trihydroxymethylpropane adduct of cresyl diisocyanate (solid content concentration 75%) ("Coronate L" (trade name), manufactured by Tosoh Corporation)

〈Silane coupling agent〉

3-Glycidoxypropyltrimethoxysilane, liquid ("KBM-403" (trade name), manufactured by Shin-Etsu Chemical Co., Ltd.)

〈Antistatic Agent〉

1-Hexylpyridinium hexafluorophosphate, a compound represented by the following formula (III).

8. ITO corrosion evaluation

An ITO film was formed on one side of an alkali-free glass by sputtering to produce a glass having an ITO film. The glass having the ITO film was cut into 25 mm × 25 mm pieces, and the center portion of the ITO film was measured using a low resistivity meter ("Loresta AX MCP-T370", manufactured by Mitsubishi Chemical Analytec) and the value was taken as the "initial resistance value". Then, the laminate (3) was cut into 15 mm × 15 mm pieces and the adhesive layer of the laminate (3) was bonded to the ITO film in contact with each other. The pieces were then autoclaved at a temperature of 50°C and a pressure of 5 kg/cm ² (490.3 kPa) for 1 hour, and then placed in an environment at a temperature of 23°C and a relative humidity of 55% for 24 hours. This was used as an evaluation sample. Then, the evaluation sample was placed in an environment of 80°C and relative humidity of 90% for 72 hours, then taken out and the laminate (3) was peeled off. Then, the ITO film was washed with methanol and measured using the same device as above as the "resistance after durability". From the "initial resistance value" and "resistance value after durability" measured as above, the ITO resistance value increase rate was calculated using the following formula, and the ITO corrosion resistance was evaluated using the following evaluation criteria. The results are shown in Table 2. The numbers in Table 2 represent the values of the increase rate of the following formula.

Resistance increase rate (%) = (resistance after durability - initial resistance) / initial resistance × 100

◎: Resistance value increase rate is less than 20%

○: Resistance value increase rate exceeds 20% but does not reach 30%

X: The resistance value increase rate is more than 30%

9. Durability evaluation of laminates

The laminate (3) was cut into a size of 30 mm x 30 mm, and after peeling off the peeling film, the adhesive layer side of the laminate (3) was bonded to an alkali-free glass ["EAGLE XG" manufactured by Corning Incorporated]. The sample was autoclaved at a temperature of 50°C and a pressure of 5 kg/ ^cm2 (490.3 kPa) for 1 hour, and then placed in an environment of a temperature of 23°C and a relative humidity of 55% for 24 hours. Then, the UV-visible spectrophotometer (manufactured by Shimadzu Corporation, "UV2450") was equipped with the optional accessory "with polarizing film holder" to measure the transmission spectrum of the multilayer in the transmission axis direction and the absorption axis direction in the range of 380 to 700 nm, and the polarization degree Py (unit: %) was obtained based on the above. The polarization degree was taken as the initial Py. Furthermore, the polarization degree was measured after standing still for 24 hours at 80°C and a relative humidity of 90%, and the polarization degree was taken as the post-test Py. Based on the above, the polarization change △Py was calculated by the following formula. The results are shown in Table 1.

△Py = Py after test - initial Py

[Examples 2 to 22 and Comparative Examples 1 to 9]

Using the curable compositions (I) of Manufacturing Examples 2 to 31, a first cured layer and a laminate (3) were obtained in the same manner as in Example 1. Using the obtained laminate (3), the ITO resistance value increase rate and polarization degree change ΔPy were calculated by the same method as in Example 1. The results are shown in Table 2.

As shown in Table 2, Examples 1 to 22 represent optical laminates having an absorbance increase rate of 30% or less in the first cured layer, which can effectively suppress ITO corrosion even when placed under high temperature and high humidity for a long time. In particular, Examples 4 to 20 and Example 22 represent optical laminates having an absorbance increase rate of 20% or less in the first cured layer, which can more effectively suppress ITO corrosion. Furthermore, Examples 1 to 22 represent optical laminates having an absorbance increase rate of 30% or less in the first cured layer, which have high durability and can maintain optical performance even under high temperature and high humidity.

As shown in Table 2, Examples 1 to 22 show that the optical laminate containing the first cured layer of 40 parts by mass or more of an oxycyclobutane compound having two or more oxycyclobutane groups relative to 100 parts by mass of the total amount of all polymerizable compounds can more effectively suppress the corrosion of ITO.

1. Polarizing film

2. First hardening layer

3. Adhesive layer

4. Conductive layer

5. The second hardening layer

6. Second protective film

10. Optical multilayers

X‧‧‧Substrate

Claims (6)

An optical laminate is a film having a dichroic pigment in a polyvinyl alcohol resin, wherein a first hardened layer, an adhesive layer and a conductive layer are sequentially laminated on one side of a polarizing film having a dichroic pigment in a polyvinyl alcohol resin; wherein the first hardened layer is adjacent to the adhesive layer, and the absorbance increase rate of the first hardened layer expressed by the following formula (1) is 20% or less; absorbance increase rate (%) = (Abs (360nm) after immersion - Abs (360nm) before immersion) / Abs (360nm) before immersion × 100 (1) In the formula, Abs (360nm) after immersion indicates the absorbance at 360nm after the hardened material is immersed in a 50% potassium iodide aqueous solution for 100 hours in an atmosphere with a temperature of 23°C and a relative humidity of 60%, and Abs (360nm) before immersion indicates the absorbance at 360nm before the hardened material is immersed in a 50% potassium iodide aqueous solution. An optical laminate is a first curable layer, an adhesive layer and a conductive layer, which are sequentially laminated on one side of a polarizing film containing a dichroic pigment in a polyvinyl alcohol resin; wherein the first curable layer is adjacent to the adhesive layer, and the polymerizable compound contains an oxycyclobutane compound having two or more oxycyclobutane groups, and the content of the oxycyclobutane compound is 40 parts by mass or more relative to 100 parts by mass of the total amount of all polymerizable compounds contained in the curable composition. An optical laminate as described in item 1 or 2 of the patent application, wherein the thickness of the first hardened layer is 0.1 to 15 μm. An optical laminate as described in item 1 or 2 of the patent application, wherein the hardener constituting the first hardener layer is a photohardener of a hardening composition containing the aforementioned polymerizable compound. The optical laminate as described in item 1 or 2 of the patent application scope is a laminate having a second cured layer and a protective film on the surface of the polarizing film opposite to the first cured layer. The optical laminate as described in Item 5 of the patent application, wherein the moisture permeability of the protective film is less than 1200g/24 hours at a temperature of 23°C and a relative humidity of 55%.

Images