JP2022190952A - adhesive composition - Google Patents

Abstract

To provide an adhesive composition, an adhesive layer and an optical laminate which can retain bonding force to a bonding object such as a polarizing plate even when the peeling force of a release film for an optical member is reduced, and can also prevent the appearance of wrinkles at a cut portion.SOLUTION: An adhesive composition contains a methacrylic resin, a crosslinker, a reactive silicone oil, and a non-reactive silicone oil.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a pressure-sensitive adhesive composition, and further relates to a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition and an optical laminate comprising the pressure-sensitive adhesive layer.

Optical members such as polarizing plates and retardation films are widely used in liquid crystal display devices and organic EL display devices. Such an optical member is laminated on a display panel via an adhesive layer when used in these display devices. The surface of the pressure-sensitive adhesive layer is protected with a release film (also referred to as a separator) until it is laminated on the display panel, and the release film is peeled off when laminating on the display panel [see, for example, Patent Documents 1].

JP 2010-066755 A

When laminating the optical member on the display panel via the pressure-sensitive adhesive layer, first, the optical member is fixed to the holding base by a method such as suction or adsorption, and the release tape is attached to the release film. After that, the release film is removed by pulling the release tape as a handle. However, when the release film is removed by peeling, the fixation of the optical member that has been fixed following the movement of the release film is released, resulting in peeling failure that the release film cannot be peeled off. This tends to become more pronounced as the thickness of the polarizing plate becomes thinner.

As a method of suppressing the peeling failure, a method of firmly fixing the optical member to the time holding base by increasing the suction force and the suction force of the optical member is conceivable. However, in such a method, as the optical member becomes thinner, the optical member may have suction traces and suction traces, which may cause poor appearance, and the problem has not yet been solved.

As another method, a method of lowering the peeling force of the peeling film is conceivable. However, simply lowering the release force causes problems such as the release film peeling off or shifting from the optical member when the optical member is cut or transported, and this method has not yet solved the problem. . When the release film is easily peeled off or shifted from the optical member when the optical member is cut, wrinkles (cut wrinkles) often occur at the cut edges.

An object of the present invention is to solve the above-mentioned problems, and to reduce the occurrence of cut wrinkles while maintaining adhesion to adherends such as polarizing plates even when the peeling force of the release film of the optical member is lowered. An object of the present invention is to provide a pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer, and an optical laminate capable of

The present invention provides the following adhesive composition, adhesive layer, and optical laminate.
[1] A pressure-sensitive adhesive composition containing a (meth)acrylic resin, a cross-linking agent, a reactive silicone oil, and a non-reactive silicone oil.
[2] The reactive silicone oil contains a reactive silicone oil having an amino group on the side chain of the polysiloxane skeleton,
The pressure-sensitive adhesive composition according to [1], wherein the non-reactive silicone oil contains a non-reactive silicone oil having an alkyl group on the side chain of the polysiloxane skeleton.
[3] The pressure-sensitive adhesive composition according to [2], wherein the amino group is a group derived from diamine.
[4] The pressure-sensitive adhesive composition according to [2], wherein the alkyl group is at least one selected from the group consisting of long-chain alkyl groups and fluoroalkyl groups.
[5] The adhesive composition according to any one of [1] to [4], further comprising a silane coupling agent.
[6] A pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to any one of [1] to [5].
[7] An optical laminate comprising an optical member, the pressure-sensitive adhesive layer described in [6], and a release film in this order.

ADVANTAGE OF THE INVENTION According to the present invention, a pressure-sensitive adhesive composition that can prevent cut wrinkles from occurring while maintaining adhesion to a member to be adhered, such as a polarizing plate, even when the peeling force of a release film of an optical member is reduced. Agent layers and optical laminates can be provided.

It is a schematic sectional drawing which shows an example of the layer structure of an optical laminated body. It is a schematic sectional drawing which shows an example of the layer structure of a polarizing plate with an adhesive layer.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. In all the drawings below, the scale of each component is adjusted appropriately to facilitate understanding, and the scale of each component shown in the drawings does not necessarily match the scale of the actual component.

<Adhesive composition>
A pressure-sensitive adhesive composition according to one aspect of the present invention comprises a (meth)acrylic resin (A), a cross-linking agent (B), a reactive silicone oil (C), and a non-reactive silicone oil (D). include.

[1] (Meth) acrylic resin (A)
(Meth)acrylic resin (A) is a polymer containing a structural unit derived from a (meth)acrylic monomer having a hydroxyl group (hereinafter sometimes referred to as acrylic polymer (A)), preferably , in addition to this building block, the formula (I):

It is a polymer containing as a main component a structural unit derived from a (meth)acrylic acid ester represented by. In the present specification, "(meth)acrylic" means acrylic and / or methacrylic, and "(meth)" when referring to "(meth)acrylate", "(meth)acryloyl", etc. has the same meaning. be.

In formula (I), R ¹¹ represents a hydrogen atom or a methyl group, R ¹² represents an alkyl group having 1 to 14 carbon atoms optionally substituted by an alkoxy group having 1 to 10 carbon atoms, or an alkyl group having 1 to 10 carbon atoms, represents an aralkyl group having 7 to 21 carbon atoms which may be substituted with an alkoxy group. R ¹² is preferably an alkyl group having 1 to 14 carbon atoms which may be substituted with an alkoxy group having 1 to 10 carbon atoms.

Examples of the (meth)acrylic acid ester represented by the formula (I) include (meth)acrylic acid alkyl esters, and specific examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, and (meth)acrylic acid. (meth)acrylic acid alkyl esters in which the alkyl moiety is linear, such as n-propyl acrylate, n-butyl (meth)acrylate, n-octyl (meth)acrylate, and lauryl (meth)acrylate; ) isopropyl acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate and the like. The number of carbon atoms in the alkyl portion of the (meth)acrylic acid alkyl ester is preferably 1-8, more preferably 1-6.

When R ¹² is an alkyl group substituted with an alkoxy group, that is, when R ¹² is an alkoxyalkyl group, specific examples of the (meth)acrylic acid ester represented by formula (I) include (meth)acryl Including 2-methoxyethyl acid, ethoxymethyl (meth)acrylate and the like. The number of carbon atoms in the alkyl group in the alkoxyalkyl group is preferably 1-8, more preferably 1-6. The alkoxy group in the alkoxyalkyl group preferably has 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms. Specific examples of the (meth)acrylic acid ester represented by Formula (I) when R ¹² is an aralkyl group having 7 to 21 carbon atoms include benzyl (meth)acrylate and the like. The aralkyl group preferably has 7 to 11 carbon atoms.

The (meth)acrylic acid esters represented by formula (I) may be used alone or in combination of two or more. Among them, the (meth)acrylic ester preferably contains an alkyl (meth)acrylate, more preferably an alkyl acrylate, and even more preferably n-butyl acrylate. The (meth)acrylic resin (A) preferably contains 50% by mass or more of structural units derived from n-butyl acrylate among all structural units constituting the resin (A). Of course, in addition to n-butyl acrylate, other (meth)acrylic acid esters represented by formula (I) can also be used in combination.

The content of the structural unit derived from the (meth)acrylic acid ester represented by formula (I) is usually 60% by mass or more and less than 100% by mass in all the structural units constituting the (meth)acrylic resin (A). preferably 70% by mass or more and 99.9% by mass or less, more preferably 80% by mass or more and 99.6% by mass or less.

The (meth)acrylic resin (A) contains a structural unit derived from a (meth)acrylic monomer having a hydroxyl group. Containing this structural unit is advantageous for enhancing the adhesion between the pressure-sensitive adhesive layer and the optical member and the durability of the pressure-sensitive adhesive layer. A suitable example of the (meth)acrylic monomer having a hydroxyl group is a (meth)acrylic acid ester having a hydroxyl group. Specific examples of (meth)acrylic acid esters having a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2 (meth)acrylic acid. - hydroxy-containing alkyl esters of (meth)acrylic acid such as (2-hydroxyethoxy)ethyl, 2- or 3-chloro-2-hydroxypropyl (meth)acrylate; polyfunctional such as diethylene glycol mono(meth)acrylate; Incomplete esters of alcohol and (meth)acrylic acid are included. The (meth)acrylic monomers having a hydroxyl group may be used singly or in combination of two or more.

Among them, the (meth)acrylic acid ester having a hydroxyl group is preferably a hydroxyl group-containing alkyl ester of (meth)acrylic acid from the viewpoint of adhesion between the pressure-sensitive adhesive layer and the optical member and durability of the pressure-sensitive adhesive layer. The number of carbon atoms in the alkyl moiety in the hydroxyl group-containing alkyl ester of (meth)acrylic acid is preferably 1 or more and 8 or less, more preferably 1 or more and 6 or less.

The content of the structural unit derived from the (meth)acrylic monomer having a hydroxyl group is preferably 6% by mass or less, more preferably 5% by mass, of the total structural units constituting the (meth)acrylic resin (A). % by mass or less, more preferably 4% by mass or less. When the content of structural units derived from a (meth)acrylic monomer having a hydroxyl group exceeds 6% by mass, the pressure-sensitive adhesive layer tends to lack durability, particularly heat resistance. On the other hand, the content of the structural unit derived from the (meth)acrylic monomer having a hydroxyl group is usually 0.5% by mass or more, preferably 0.7% by mass or more, and more preferably 1% by mass or more. is. When the content of the structural unit derived from the (meth)acrylic monomer having a hydroxyl group is less than 0.5% by mass, the adhesion between the adhesive layer and the optical member and the durability of the adhesive layer are insufficient. There is a tendency.

The (meth)acrylic resin (A) can contain a structural unit derived from a monomer having a polar functional group other than the (meth)acrylic monomer having a hydroxyl group. Another monomer having a polar functional group is preferably a (meth)acrylic monomer having a polar functional group. Examples of the polar functional group that the monomer has include a carboxyl group (free carboxyl group), an amino group, a heterocyclic group (for example, an epoxy group), and the like.

Specific examples of monomers having other polar functional groups include (meth)acrylic monomers having a carboxyl group such as acrylic acid, methacrylic acid, β-carboxyethyl (meth)acrylate; acryloylmorpholine, vinylcaprolactam , N-vinyl-2-pyrrolidone, vinylpyridine, tetrahydrofurfuryl (meth)acrylate, caprolactone-modified tetrahydrofurfuryl acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, glycidyl (meth)acrylate, 2,5-dihydro monomers having a heterocyclic group such as furan; amino groups different from heterocyclic groups such as aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and dimethylaminopropyl (meth)acrylate; Including monomers having Monomers having other polar functional groups may be used alone or in combination of two or more.

In addition to a (meth)acrylic monomer having a hydroxyl group, a monomer having another polar functional group, among others, a (meth)acrylic monomer having a carboxyl group can be used in combination with the pressure-sensitive adhesive layer. It is advantageous in enhancing the adhesion to optical members and the durability (especially heat resistance) of the pressure-sensitive adhesive layer.

The lower limit of the content of structural units derived from monomers having other polar functional groups, preferably structural units derived from (meth)acrylic monomers having a carboxyl group, is the (meth)acrylic resin ( It can be 0% by mass or more in all structural units constituting A). As described above, the (meth)acrylic resin (A) preferably contains a structural unit derived from a (meth)acrylic monomer having a carboxyl group, and the content of the (meth)acrylic resin is It is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and still more preferably 2% by mass or more in all structural units constituting (A). If the content of structural units derived from monomers having other polar functional groups is less than 0.05% by mass, the effect of use is hardly recognized. On the other hand, the content of structural units derived from monomers having other polar functional groups, preferably (meth)acrylic monomers having a carboxyl group, is It is preferably 5% by mass or less, more preferably 4% by mass or less, and still more preferably 3% by mass or less in the constituent units. If the content of structural units derived from other monomers having polar functional groups exceeds 5% by mass, the durability, particularly heat resistance, of the pressure-sensitive adhesive layer tends to be insufficient. Structural units derived from all monomers having a polar functional group, including a (meth)acrylic monomer having a hydroxyl group, are usually 1 mass in all structural units constituting the (meth)acrylic resin (A). % or more and 10 mass % or less, preferably 1.1 mass % or more and 8 mass % or less.

(Meth)acrylic resin (A) is a monomer having one olefinic double bond and at least one aromatic ring in the molecule (provided that the above formula (I) or the above polar functional group excluding those corresponding to monomers) may further contain a structural unit derived from Suitable examples of such monomers include (meth)acrylic monomers having an aromatic ring. (Meth)acrylic monomers having such an aromatic ring include neopentyl glycol benzoate (meth)acrylate and the like, and particularly formula (II):

A (meth)acrylic acid ester having an aryloxyalkyl group such as a phenoxyethyl group-containing (meth)acrylic acid ester represented by is preferable. A monomer having one olefinic double bond and at least one aromatic ring in the molecule, such as a phenoxyethyl group-containing (meth)acrylic acid ester, may be used singly or two. More than one species may be used in combination.

In formula (II), R ¹³ represents a hydrogen atom or a methyl group, q represents an integer of 1 to 8, and R ¹⁴ represents a hydrogen atom, an alkyl group, an aralkyl group or an aryl group. When R ¹⁴ is an alkyl group, it may have about 1 to 9 carbon atoms; when it is an aralkyl group, it has about 7 to 11 carbon atoms; and when it is an aryl group, it has 6 carbon atoms. It can be on the order of ~10.

Examples of alkyl groups having 1 to 9 carbon atoms constituting R ¹⁴ in formula (II) include methyl, butyl, nonyl, etc. Examples of aralkyl groups having 7 to 11 carbon atoms include benzyl, phenethyl, naphthylmethyl, etc. Examples of aryl groups having 6 to 10 carbon atoms include phenyl, tolyl, naphthyl and the like.

Specific examples of the phenoxyethyl group-containing (meth)acrylic acid ester represented by formula (II) include 2-phenoxyethyl (meth)acrylate, 2-(2-phenoxyethoxy)ethyl (meth)acrylate, and ethylene oxide. (Meth)acrylic acid ester of modified nonylphenol, 2-(o-phenylphenoxy)ethyl (meth)acrylate and the like. Among them, the phenoxyethyl group-containing (meth)acrylic acid ester is 2-phenoxyethyl (meth)acrylate, 2-(o-phenylphenoxy)ethyl (meth)acrylate and/or 2-(2 -phenoxyethoxy)ethyl.

The content of structural units derived from a monomer having one olefinic double bond and at least one aromatic ring in the molecule is the total structural units constituting the (meth)acrylic resin (A) , usually 0% by mass or more and 20% by mass or less (for example, 6% by mass or more and 12% by mass or less).

The (meth)acrylic resin (A) includes the (meth)acrylic acid ester represented by the formula (I) described above, a monomer having a polar functional group, and one olefinic double Structural units derived from monomers other than monomers having a bond and at least one aromatic ring (hereinafter also referred to as "other monomers") may be included. Examples of other monomers include structural units derived from (meth)acrylic acid esters having an alicyclic structure in the molecule, structural units derived from styrene-based monomers, and vinyl-based monomers. Structural units, structural units derived from monomers having multiple (meth)acryloyl groups in the molecule, structural units derived from (meth)acrylamide compounds, and the like can be mentioned. Other monomers may be used singly or in combination of two or more.

The alicyclic structure in the (meth)acrylic acid ester having an alicyclic structure in the molecule is a cycloparaffin structure having usually 5 or more carbon atoms, preferably about 5 to 7 carbon atoms. Specific examples of (meth)acrylates having an alicyclic structure include isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, cyclododecyl (meth)acrylate, ( meth)methylcyclohexyl acrylate, trimethylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, cyclohexylphenyl (meth)acrylate, cyclohexyl α-ethoxyacrylate and the like.

Specific examples of styrenic monomers include styrene; alkylstyrenes such as methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene, and octylstyrene; Halogenated styrenes such as fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, iodostyrene; 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 vinylpyridine, vinylpyrrolidone and vinylcarbazole; conjugated diene monomers such as butadiene, isoprene and chloroprene; acrylonitrile, methacrylonitrile and the like.

Specific examples of monomers having multiple (meth)acryloyl groups in the molecule include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and 1,9-nonanediol. Di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, etc. having two (meth) in the molecule monomers having acryloyl groups; monomers having three (meth)acryloyl groups in the molecule such as trimethylolpropane tri(meth)acrylate;

Specific examples of (meth)acrylamide compounds include N-methylol(meth)acrylamide, N-(2-hydroxyethyl)(meth)acrylamide, N-(3-hydroxypropyl)(meth)acrylamide, N-(4-hydroxy Butyl) (meth) acrylamide, N-(5-hydroxypentyl) (meth) acrylamide, N-(6-hydroxyhexyl) (meth) acrylamide, N,N-dimethyl (meth) acrylamide, N,N-diethyl (meth) ) acrylamide, N-isopropyl(meth)acrylamide, N-(3-dimethylaminopropyl)(meth)acrylamide, N-(1,1-dimethyl-3-oxobutyl)(meth)acrylamide, N-[2-(2 -Oxo-1-imidazolidinyl)ethyl](meth)acrylamide, 2-acryloylamino-2-methyl-1-propanesulfonic acid, N-(methoxymethyl)acrylamide, N-(ethoxymethyl)(meth)acrylamide, N- (Propoxymethyl)(meth)acrylamide, N-(1-methylethoxymethyl)(meth)acrylamide, N-(1-methylpropoxymethyl)(meth)acrylamide, N-(2-methylpropoxymethyl)(meth)acrylamide [alias: N-(isobutoxymethyl)(meth)acrylamide], N-(butoxymethyl)(meth)acrylamide, N-(1,1-dimethylethoxymethyl)(meth)acrylamide, N-(2-methoxyethyl) ) (meth)acrylamide, N-(2-ethoxyethyl)(meth)acrylamide, N-(2-propoxyethyl)(meth)acrylamide, N-[2-(1-methylethoxy)ethyl](meth)acrylamide, N-[2-(1-methylpropoxy)ethyl](meth)acrylamide, N-[2-(2-methylpropoxy)ethyl](meth)acrylamide [alias: N-(2-isobutoxyethyl) (meth) acrylamide], N-(2-butoxyethyl)(meth)acrylamide, N-[2-(1,1-dimethylethoxy)ethyl](meth)acrylamide and the like. Among them, N-(methoxymethyl)acrylamide, N-(ethoxymethyl)acrylamide, N-(propoxymethyl)acrylamide, N-(butoxymethyl)acrylamide and N-(2-methylpropoxymethyl)acrylamide are preferably used.

The (meth)acrylic resin (A) contains structural units derived from other monomers in the total structural units constituting it, usually 0% by mass or more and 20% by mass or less, preferably 0% by mass or more and 10% by mass. Contained in the following proportions.

The content of the (meth)acrylic resin (A) in the pressure-sensitive adhesive composition is not particularly limited, but may be, for example, 0.01% by mass or more and 90% by mass or less, preferably 0.1% by mass or more and 60% by mass. Below, it is more preferably 1 mass % or more and 40 mass % or less. The pressure-sensitive adhesive composition may contain two or more (meth)acrylic resins belonging to the (meth)acrylic resin (A). Moreover, the adhesive composition may contain other (meth)acrylic resins different from the (meth)acrylic resin (A). Another example of the (meth)acrylic resin is a (meth)acrylic resin having a structural unit derived from a (meth)acrylic acid ester represented by formula (I) and having no polar functional group. . However, the adhesive composition preferably contains (meth)acrylic resin (A) as a main component, and the content of (meth)acrylic resin (A) is Of the total, it is preferably 60% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and particularly preferably 95% by mass or more (for example, 100% by mass).

The (meth)acrylic resin (A) has a glass transition temperature (Tg) measured by a differential scanning calorimeter (DSC) of -20°C or lower, preferably -25°C or lower. According to the pressure-sensitive adhesive composition according to the present invention containing a (meth)acrylic resin (A) having a Tg of −20° C. or less, the adhesion between the pressure-sensitive adhesive layer and the optical member and the durability of the pressure-sensitive adhesive layer can be improved. can be improved. From the viewpoint of the durability of the pressure-sensitive adhesive layer, the Tg of the (meth)acrylic resin (A) is usually −55° C. or higher, preferably −50° C. or higher.

Further, according to the pressure-sensitive adhesive composition of the present invention containing the (meth)acrylic resin (A) having a Tg of −20° C. or less, it is possible to shorten the curing time of the pressure-sensitive adhesive layer. That is, the pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) is generally cured in order to allow the cross-linking reaction to proceed to such an extent that appropriate handleability and workability can be obtained, but the pressure-sensitive adhesive composition according to the present invention According to the method, it is possible to shorten the curing time of the pressure-sensitive adhesive layer necessary for the cross-linking reaction to proceed sufficiently.

The (meth)acrylic resin (A) preferably has a weight average molecular weight (Mw) of 500,000 or more and 2,000,000 or less in terms of standard polystyrene by gel permeation chromatography (GPC). It is more preferably in the range of 10,000 or less. When the Mw is 500,000 or more, the adhesiveness between the adhesive layer and the optical member is improved in a high-temperature and high-humidity environment, and the possibility of floating or peeling between the adhesive layer and the optical member is low. and the reworkability of the pressure-sensitive adhesive layer tends to improve. Further, if the Mw is 2,000,000 or less, even if the dimensions of the optical member change when the pressure-sensitive adhesive layer is adhered to the optical member, the pressure-sensitive adhesive layer tends to fluctuate following the dimensional change. This is advantageous in terms of the adhesion between the adhesive layer and the optical member and the durability of the adhesive layer. There is no difference between the brightness of the part and the brightness of the central part, and white spots and color unevenness tend to be suppressed. 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 usually about 2-10, preferably 3-7.

The (meth)acrylic resin (A) and other (meth)acrylic resins that can optionally be used in combination are produced by known methods such as solution polymerization, bulk polymerization, suspension polymerization, and emulsion polymerization. be able to. A polymerization initiator is usually used in the production of (meth)acrylic resins. The polymerization initiator is used in an amount of 0.001 parts by mass or more and 5 parts by mass or less with respect to a total of 100 parts by mass of all monomers used in the production of the (meth)acrylic resin. Also, the (meth)acrylic resin may be produced by a method in which polymerization is progressed by, for example, active energy rays such as ultraviolet rays.

A thermal polymerization initiator, a photopolymerization initiator, or the like is used as the polymerization initiator. Examples of photopolymerization initiators include 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone and the like. Examples of thermal polymerization initiators include 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), dimethyl-2,2′-azobis(2-methylpropio azo compounds such as 2,2′-azobis (2-hydroxymethylpropionitrile); lauryl peroxide, tert-butyl hydroperoxide, benzoyl peroxide, tert-butyl peroxybenzoate, cumene hydroperoxide organic compounds such as oxides, diisopropyl peroxydicarbonate, dipropyl peroxydicarbonate, tert-butyl peroxyneodecanoate, tert-butyl peroxypivalate, (3,5,5-trimethylhexanoyl) peroxide. Peroxides; inorganic peroxides such as potassium persulfate, ammonium persulfate and hydrogen peroxide. A redox initiator using a peroxide and a reducing agent in combination may also be used as the polymerization initiator.

As a method for producing a (meth)acrylic resin, the solution polymerization method is preferable among the methods shown above. An example of the solution polymerization method is to mix the monomers and an organic solvent to be used, add a thermal polymerization initiator under a nitrogen atmosphere, and heat at about 40 to 90° C., preferably about 50 to 80° C. for 3 to 15 hours. Stir to some extent. In order to control the reaction, a monomer or a thermal polymerization initiator may be added continuously or intermittently during polymerization, or may be added in a state of being dissolved in an organic solvent. Examples of organic solvents include aromatic hydrocarbons such as toluene and xylene; esters such as ethyl acetate and butyl acetate; aliphatic alcohols such as propyl alcohol and isopropyl alcohol; acetone, methyl ethyl ketone and methyl isobutyl ketone. Ketones such as can be used.

[2] Crosslinking agent (B)
The cross-linking agent (B) is a compound that reacts with a structural unit derived from a polar functional group-containing monomer in the base polymer such as the (meth)acrylic resin (A) to cross-link the base polymer. Specific examples include isocyanate-based compounds, epoxy-based compounds, aziridine-based compounds, metal chelate-based compounds, and the like. Among them, it is preferable to use an isocyanate-based compound as a cross-linking agent, which can further enhance the adhesion between the pressure-sensitive adhesive layer and the optical member and the durability of the pressure-sensitive adhesive layer. , also called an isocyanate cross-linking agent). The isocyanate-based compound, epoxy-based compound and aziridine-based compound have at least two functional groups in the molecule that can react with the polar functional group in the base polymer. The crosslinking agent (B) may be used alone or in combination of two or more.

An isocyanate compound is a compound having at least two isocyanate groups (--NCO) in the molecule. Specific examples of isocyanate compounds include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate and the like. Adducts obtained by reacting these isocyanate compounds with polyols such as glycerol and trimethylolpropane, and dimers, trimers, etc. of isocyanate compounds can also be used as the cross-linking agent (B).

An epoxy-based compound is a compound having at least two epoxy groups in the molecule. Specific examples of epoxy compounds include bisphenol A type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane. Including triglycidyl ether, N,N-diglycidylaniline, N,N,N',N'-tetraglycidyl-m-xylenediamine, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, etc. .

An aziridine-based compound is a compound having at least two 3-membered ring skeletons consisting of one nitrogen atom and two carbon atoms, also called ethyleneimine, in the molecule. Specific examples of aziridine compounds include diphenylmethane-4,4′-bis(1-aziridinecarboxamide), toluene-2,4-bis(1-aziridinecarboxamide), triethylenemelamine, isophthaloylbis-1-(2 -methylaziridine), tris-1-aziridinylphosphine oxide, hexamethylene-1,6-bis(1-aziridinecarboxamide), trimethylolpropane-tris-β-aziridinylpropionate, tetramethylolmethane-tris -β-aziridinyl propionate and the like.

Specific examples of metal chelate compounds include compounds in which polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium and zirconium are coordinated with acetylacetone or ethyl acetoacetate. include.

The cross-linking agent (B) is, for example, 0.01 parts by mass or more and 10 parts by mass or less, preferably 0.1 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the (meth)acrylic resin (A). It is contained in the adhesive composition. When the content of the cross-linking agent (B) is 0.01 parts by mass or more, preferably 0.1 parts by mass or more, the durability of the pressure-sensitive adhesive layer tends to be improved.

[3] Reactive silicone oil (C) and non-reactive silicone oil (D)
The adhesive composition contains reactive silicone oil (C) and non-reactive silicone oil (D). Silicone oil is a compound having a siloxane bond as a skeleton, and is also called polysiloxane because it has a siloxane bond. Side chains and both ends are usually alkyl groups, and it is usually liquid. By including both the reactive silicone oil (C) and the non-reactive silicone oil (D) in the pressure-sensitive adhesive composition, even when the release force of the release film on the pressure-sensitive adhesive layer surface of the optical member is reduced, the polarizing plate, etc. It is possible to obtain a pressure-sensitive adhesive layer capable of suppressing defects during processing or transportation of an optical member while maintaining the adhesion to an adherend.

[Reactive silicone oil (C)]
Reactive silicone oil (C) has a structure in which one or more of polysiloxane side chains, both ends and one end are substituted with reactive organic groups. Some or all of the side chains of the polysiloxane can be substituted with reactive organic groups. Among them, a reactive silicone oil in which a crosslinkable functional group is introduced into the side chain of the polysiloxane skeleton (hereinafter also referred to as a side chain type reactive silicone oil) is preferably used. The side chains can be, for example, methyl groups.

Examples of crosslinkable functional groups include amino groups, epoxy groups, mercapto groups, carboxyl groups, isocyanate groups, and methacrylate groups. Among these, an amino group is preferable, a group derived from a monoamine and a group derived from a diamine are more preferable, and a group derived from a diamine is most preferable. A group derived from a monoamine can be, for example, a group of the formula: --RNH ₂ . A group derived from a diamine can be, for example, a group of the formula: --RNH--R'NH ₂ .

The reactive silicone oil (C) preferably includes a reactive silicone oil having an amino group in the side chain of the polysiloxane skeleton (hereinafter also referred to as a side chain type amino-modified silicone oil), more preferably a polysiloxane skeleton. It contains a reactive silicone oil having a diamine-derived group in its side chain (hereinafter also referred to as a side chain type diamine-modified silicone oil), and more preferably contains only a side chain type diamine-modified silicone oil. When the reactive silicone oil (C) contains a side chain type diamine-modified silicone oil, the side chain type diamine-modified silicone oil can contribute to prevention of cut wrinkles. Since the diamine-modified silicone oil tends to have high wettability with respect to the release film, the pressure-sensitive adhesive layer is formed so as to fill the unevenness of the release film surface. As a result, the adhesion between the adhesive layer and the release film is improved, and the adhesion between the adhesive layer and the release film can withstand impact (shear stress) during cutting. Therefore, it is presumed that the occurrence of cut wrinkles is prevented.

Examples of such reactive silicone oil (C) include commercially available products such as “KF-865”, “KF-864”, “KF-859”, “KF-860” and “KF-860” manufactured by Shin-Etsu Chemical Co., Ltd. KF-8004”, “KF-8005” and the like. Only one type of reactive silicone oil may be used, or two or more types may be used in combination.

The functional group equivalent weight of the side chain type amino-modified silicone oil may be, for example, 350 g/mol or more and 60000 g/mol or less, preferably 1000 g/mol or more and 20000 g/mol or less, and more preferably 1500 g/mol or more and 15000 g/mol or more. mol.

The reactive silicone oil (C) is, for example, 0.001 parts by mass or more and 0.5 parts by mass or less, preferably 0.006 parts by mass or more and 0.3 parts by mass with respect to 100 parts by mass of the (meth)acrylic resin (A). It is contained in the pressure-sensitive adhesive composition in a proportion of 0.009 to 0.1 part by mass or less, more preferably 0.009 to 0.1 part by mass.

[Non-reactive silicone oil (D)]
The non-reactive silicone oil (D) has a structure in which one or more of polysiloxane side chains, both terminals and one terminal are substituted only with non-reactive organic groups. Some or all of the polysiloxane side chains can be substituted with non-reactive organic groups. Among them, a non-reactive silicone oil in which a non-crosslinkable functional group is introduced into the side chain of the polysiloxane skeleton (hereinafter also referred to as a side chain-type non-reactive silicone oil) is preferably used. The side chains can be, for example, methyl groups.

Examples of non-crosslinkable functional groups include alkyl groups, polyether groups, and polyester groups. Among these, an alkyl group is preferable. The alkyl group may be at least one selected from the group consisting of long-chain alkyl groups and fluoroalkyl groups, preferably long-chain alkyl groups. A long-chain alkyl group can be, for example, a group represented by the formula: -C _a H _2a+1 , where a is an integer of 2 or greater. a can be an integer of 9 or less. A fluoroalkyl group can be, for example, a group of the formula: --CH ₂ CH ₂ CF ₃ .

The non-reactive silicone oil (D) preferably includes a non-reactive silicone oil having an alkyl group on the side chain of the polysiloxane skeleton (hereinafter also referred to as a side chain type alkyl group-modified silicone oil), more preferably poly Non-reactive silicone oils having long-chain alkyl groups on the side chains of the siloxane skeleton (hereinafter also referred to as side-chain long-chain alkyl-modified silicone oils) and non-reactive silicones having fluoroalkyl groups on the side chains of the polysiloxane skeleton containing at least one selected from the group consisting of oils (hereinafter also referred to as side-chain fluoroalkyl-modified silicone oils), more preferably side-chain long-chain alkyl-modified silicone oils and side-chain fluoroalkyl-modified silicone oils It contains only at least one selected from the group consisting of silicone oils, and particularly preferably contains only side chain type long-chain alkyl-modified silicone oils. When the non-reactive silicone oil (D) contains a side-chain type long-chain alkyl-modified silicone oil, the side-chain type long-chain alkyl-modified silicone oil maintains the adhesion between the pressure-sensitive adhesive layer and the protective film of the polarizing plate. It is possible to effectively reduce the adhesion between the pressure-sensitive adhesive layer and the release film. The long-chain alkyl-modified silicone oil is less likely to localize near the protective film side surface of the polarizing plate in the pressure-sensitive adhesive layer, but tends to localize near the release film side surface. Therefore, it is presumed that the adhesiveness between the protective film of the polarizing plate and the pressure-sensitive adhesive layer is unlikely to be deteriorated even though it is a release agent.

Examples of such non-reactive silicone oil (D) include commercially available products such as "KF-4003", "KF-4917", "KF-414", and "X-22-821" manufactured by Shin-Etsu Chemical Co., Ltd. ”, “X-22-822” and the like. Only one type of the non-reactive silicone oil (D) may be used, or two or more types may be used in combination.

The non-reactive silicone oil (D) is, for example, 0.005 parts by mass or more and 1 part by mass or less, preferably 0.05 parts by mass or more and 0.5 parts by mass with respect to 100 parts by mass of the (meth)acrylic resin (A) parts or less, more preferably 0.07 to 0.5 parts by mass, more preferably 0.1 to 0.3 parts by mass in the pressure-sensitive adhesive composition.

The content ratio of the non-reactive silicone oil (D) to 1 part by mass of the reactive silicone oil (C) in the adhesive composition is preferably 1 part by mass or more and 40 parts by mass or less, more preferably 3 parts by mass or more and 30 parts by mass. parts or less, more preferably 5 parts by mass or more and 25 parts by mass or less.

[4] Silane coupling agent (E)
The adhesive composition can further contain a silane coupling agent (E). Thereby, the adhesion between the adhesive layer and an optical member such as a glass substrate can be further enhanced.

Examples of the silane coupling agent (E) include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(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-mercaptopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane , 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyldimethoxymethylsilane, 3-glycidoxypropylethoxydimethylsilane and the like. Two or more silane coupling agents may be used.

The silane coupling agent (E) may be of silicone oligomer type. Examples of silicone oligomers in the form of (monomer) oligomers include the following.

3-mercaptopropyltrimethoxysilane-tetramethoxysilane copolymer, 3-mercaptopropyltrimethoxysilane-tetraethoxysilane copolymer, 3-mercaptopropyltriethoxysilane-tetramethoxysilane copolymer, 3-mercaptopropyltriethoxysilane-tetraethoxysilane Mercaptopropyl group-containing copolymers such as copolymers;
Mercaptomethyl group-containing compounds such as mercaptomethyltrimethoxysilane-tetramethoxysilane copolymer, mercaptomethyltrimethoxysilane-tetraethoxysilane copolymer, mercaptomethyltriethoxysilane-tetramethoxysilane copolymer, and mercaptomethyltriethoxysilane-tetraethoxysilane copolymer. copolymer;
3-glydidoxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-glydidoxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-glydidoxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-glydidoxy Propyltriethoxysilane-tetraethoxysilane copolymer, 3-glydidoxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-glydidoxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-glydidoxypropylmethyldiethoxysilane - copolymers containing 3-glydidoxypropyl groups such as tetramethoxysilane copolymer, 3-glydidoxypropylmethyldiethoxysilane-tetraethoxysilane copolymer;
3-methacryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropyltriethoxysilane -tetraethoxysilane copolymer, 3-methacryloyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, 3 - copolymers containing methacryloyloxypropyl groups, such as methacryloyloxypropylmethyldiethoxysilane-tetraethoxysilane copolymers;
3-acryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltriethoxysilane -tetraethoxysilane copolymer, 3-acryloyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, 3 - copolymers containing acryloyloxypropyl groups, such as acryloyloxypropylmethyldiethoxysilane-tetraethoxysilane copolymers;
vinyltrimethoxysilane-tetramethoxysilane copolymer, vinyltrimethoxysilane-tetraethoxysilane copolymer, vinyltriethoxysilane-tetramethoxysilane copolymer, vinyltriethoxysilane-tetraethoxysilane copolymer, vinylmethyldimethoxysilane-tetramethoxysilane copolymer, vinyl group-containing copolymers such as vinylmethyldimethoxysilane-tetraethoxysilane copolymer, vinylmethyldiethoxysilane-tetramethoxysilane copolymer, vinylmethyldiethoxysilane-tetraethoxysilane copolymer;
3-aminopropyltrimethoxysilane-tetramethoxysilane copolymer, 3-aminopropyltrimethoxysilane-tetraethoxysilane copolymer, 3-aminopropyltriethoxysilane-tetramethoxysilane copolymer, 3-aminopropyltriethoxysilane-tetraethoxysilane Copolymer, 3-aminopropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-aminopropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-aminopropylmethyldiethoxysilane-tetramethoxysilane copolymer, 3-aminopropylmethyldiethoxysilane - copolymers containing amino groups, such as tetraethoxysilane copolymers, and the like.

Most of the silane coupling agents (E) exemplified above are liquid. The content of the silane coupling agent (E) in the pressure-sensitive adhesive composition is usually 0.01 parts by mass or more and 10 parts by mass or less, preferably 0, per 100 parts by mass of the (meth)acrylic resin (A). 05 parts by mass or more and 5 parts by mass or less, more preferably 0.2 parts by mass or more and 0.5 parts by mass or less. When the content of the silane coupling agent (E) is 0.01 parts by mass or more, the effect of improving the adhesion between the pressure-sensitive adhesive layer and an optical member such as a glass substrate is likely to be obtained. Moreover, when the content is 10 parts by mass or less, bleeding out of the silane coupling agent (E) from the pressure-sensitive adhesive layer can be suppressed.

[5] Ionic compound The adhesive composition may further contain an ionic compound as an antistatic agent for imparting antistatic properties to the adhesive layer. An ionic compound is a compound having an inorganic or organic cation and an inorganic or organic anion. Two or more ionic compounds may be used.

The content of the ionic compound in the pressure-sensitive adhesive composition may be, for example, 0.2 parts by mass or more and 8 parts by mass or less, preferably 0.2 parts by mass with respect to 100 parts by mass of the (meth)acrylic resin (A). It is from 0.3 parts by mass to 5 parts by mass, and more preferably from 0.5 parts by mass to 3 parts by mass. When the content of the ionic compound is 0.2 parts by mass or more, it is advantageous for improving the antistatic performance, and when it is 8 parts by mass or less, it is advantageous for maintaining the durability of the pressure-sensitive adhesive layer.

[6] Other components The adhesive composition includes a solvent, a crosslinking catalyst, a weather stabilizer, a tackifier, a plasticizer, a softening agent, a dye, a pigment, an inorganic filler, light scattering fine particles, a (meth)acrylic resin (A ) can contain additives such as resins. In addition, it is also useful to add an ultraviolet curable compound to the pressure-sensitive adhesive composition, form a pressure-sensitive adhesive layer, and then irradiate the compound with ultraviolet rays to cure it to form a harder pressure-sensitive adhesive layer. Conventionally known solvents can be used as the solvent, and examples thereof include ethyl acetate. Examples of cross-linking catalysts include amine compounds such as hexamethylenediamine, ethylenediamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethylenetetramine, isophoronediamine, trimethylenediamine, polyamino resins and melamine resins.

<Adhesive layer>
A pressure-sensitive adhesive layer according to another aspect of the present invention contains the above-described pressure-sensitive adhesive composition according to the present invention, and typically consists of the pressure-sensitive adhesive composition according to the present invention. The pressure-sensitive adhesive layer can be obtained by dissolving or dispersing each component constituting the above-mentioned pressure-sensitive adhesive composition in a solvent to form a solvent-containing pressure-sensitive adhesive composition, then coating it on a substrate film, and drying it. . The pressure-sensitive adhesive layer of the present invention has excellent adhesion to optical members as described later. In addition, although the pressure-sensitive adhesive layer of the present invention has a low peeling force with respect to the release film that protects the pressure-sensitive adhesive layer, the occurrence of defects such as poor peeling during processing and transportation of the optical member is suppressed. is. When the pressure-sensitive adhesive layer is included in the optical member described below, the pressure-sensitive adhesive layer may contain a base film.

The base film is generally a plastic film, and a typical example thereof is a release film (separator) to which a release treatment has been applied. The release film is, for example, a film made of various resins such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate, and polyarate, and the surface on which the pressure-sensitive adhesive layer is formed is subjected to release treatment such as silicone treatment. can. The release film can be peeled off from the pressure-sensitive adhesive layer. For example, an optical laminate can be obtained by directly applying an adhesive composition to the release-treated surface of a release film to form an adhesive layer, and laminating this adhesive layer with a release film onto an optical member. Alternatively, the adhesive composition may be directly applied to the surface of the optical member to form an adhesive layer, and if necessary, a release film may be laminated on the outer surface of the adhesive layer to form an optical laminate. When the pressure-sensitive adhesive layer is provided on the surface of the optical member, it is preferable to subject the bonding surface of the optical member and/or the bonding surface of the pressure-sensitive adhesive layer to surface activation treatment such as plasma treatment or corona treatment. Treatment is more preferred.

The thickness of the adhesive layer may be, for example, 10 μm or more and 45 μm or less, preferably 10 μm or more and 35 μm or less, and more preferably 10 μm or more and 25 μm or less. When the thickness of the pressure-sensitive adhesive layer is within the above range, it is advantageous for the adhesion between the pressure-sensitive adhesive layer and the optical member and the durability when the pressure-sensitive adhesive layer is bonded to the optical member. For the same reason, the adhesive layer preferably has a gel fraction in the range of 30% or more and 85% or less.

<Optical laminate>
An optical layered body according to still another aspect of the present invention has an optical member, the pressure-sensitive adhesive layer described above, and a release film in this order. The optical laminate preferably comprises the above-described pressure-sensitive adhesive layer, has an optical member in contact with one side of the pressure-sensitive adhesive layer, and has a release film in contact with the other side of the pressure-sensitive adhesive layer. Examples of the optical member with an adhesive layer include composite films such as linear polarizing plates and circular polarizing plates, translucent (preferably optically transparent) resins such as chain polyolefin resins (polypropylene resins, etc.). ), polyolefin-based resins such as cyclic polyolefin-based resins (norbornene-based resins, etc.); cellulose-based resins such as triacetylcellulose and diacetylcellulose; polyester-based resins; polycarbonate-based resins; (meth)acrylic-based resins; polyether ether ketone resin; polysulfone resin; and polyimide resin. When the optical member is a polarizing plate, the optical laminate can be a polarizing plate with an adhesive layer.

A linear polarizer can comprise a polarizer and a protective film. The polarizer and the protective film may be laminated via a bonding layer such as an adhesive layer or an adhesive layer. A polarizer is a film that has the function of extracting linearly polarized light from incident natural light. There is. Although the thickness of the polarizer is not particularly limited, it is usually 0.5 μm or more and 35 μm or less.

The protective film is made of translucent (preferably optically transparent) resin, for example, polyolefin resin such as linear polyolefin resin (polypropylene resin, etc.), cyclic polyolefin resin (norbornene resin, etc.). Cellulose resins such as triacetyl cellulose and diacetyl cellulose; polyester resins; polycarbonate resins; (meth)acrylic resins; polystyrene resins; polyether ether ketone resins; can be.

The polarizing plate can include the linear polarizing plate and the retardation film described above. For example, as a viewing angle compensation film used for optical compensation of a liquid crystal cell having a liquid crystal layer containing liquid crystal molecules aligned in a homogeneous alignment in the absence of an electric field (hereinafter referred to as an IPS mode liquid crystal cell), the polarizing element side It can be a retardation film having a first optical compensation layer and a second optical compensation layer in this order. At this time, the surface of the second optical compensation layer can be attached to the liquid crystal cell using an adhesive layer or the like. The absorption axis of the polarizing element and the slow axis of the second optical compensation layer are substantially parallel. From the viewpoint of thinning the polarizing plate, both the first optical compensation layer and the second optical compensation layer are preferably made of a cured polymerizable liquid crystal compound. The first optical compensation layer and the second optical compensation layer can satisfy the following formulas (1) and (2).
nz1 > nx1 = ny1 (1)
nx2>ny2≧nz2 (2)

Here, the refractive indices in the in-plane slow axis direction of the first optical compensation layer and the second optical compensation layer are nx1 and nx2, the in-plane fast axis refractive indices are ny1 and ny2, and the thickness Let nz1 and nz2 be the refractive indices in the directions. Each refractive index in the above formula (1) and each refractive index in the above formula (2) are values measured at the same wavelength.

The term "substantially parallel" includes not only completely parallel but also substantially parallel, and the angle is generally within ±2°, preferably within ±1°, more preferably within ±1°. is within ±0.5°. In addition, "substantially orthogonal" includes not only completely orthogonal but also substantially orthogonal, and the angle is generally in the range of 90 ± 2 °, preferably 90 ± 1 °, more preferably is in the range of 90±0.5°.

(First optical compensation layer, second optical compensation layer)
The first optical compensation layer and the second optical compensation layer can be made of a cured polymerizable liquid crystal compound. The first optical compensation layer and the second optical compensation layer may be made of the same material, or may be made of different materials. A known polymerizable liquid crystal compound can be used. Further, the wavelength dispersion characteristics of the retardation values of the first optical compensation layer and the second optical compensation layer are not particularly limited, and from positive wavelength dispersion to reverse wavelength dispersion can be suitably used. As a particularly preferable form, both the first optical compensation layer and the second optical compensation layer have reverse wavelength dispersion characteristics.

That the wavelength dispersion characteristics of the retardation values of the first optical compensation layer and the second optical compensation layer have reverse wavelength dispersion characteristics means that the following formulas (3) to (6) are satisfied.
Rth1(450)/Rth1(550)≤1.00 (3)
1.00≦Rth1(650)/Rth1(550) (4)
Re2(450)/Re2(550)≤1.00 (5)
1.00≦Re2(650)/Re2(550) (6)

where Rth1(λ)={(nx1+ny1)/2−nz1}×d1, Rth2(λ)={(nx2+ny2)/2−nz2}×d2, Re1(λ)=(nx1−ny1)×d1, Re2(λ)=(nx2−ny2)×d2, where d1 and d2 are the thicknesses of the first optical compensation layer and the second optical compensation layer, respectively, and λ is the measurement wavelength.

Examples of the materials for the first optical compensation layer and the second optical compensation layer include: 2010-241919, JP 2010-024438, JP 2011-162678, JP 2011-207765, JP 2010-270108, JP 2011-246381, JP 2012-021068, JP 2016-121339, JP 2018- 087152, JP-A-2017-179367, JP-A-2017-210601, JP-A-2019-151763, JP-A-6700468, JP-A-2020-074021, and the like are suitable materials.

The optical properties of the first optical compensation layer and the second optical compensation layer preferably satisfy the following (7) to (10).
0 nm ≤ Re1(550) ≤ 5 nm (7)
−200 nm≦Rth1(550)≦−20 nm (8)
110 nm ≤ Re2(550) ≤ 150 nm (9)
35 nm ≤ Rth2 (550) ≤ 105 nm (10)

More preferably, the optical properties of the first optical compensation layer and the second optical compensation layer satisfy the following (7a) to (10a).
0 nm ≤ Re1(550) ≤ 5 nm (7a)
−120 nm≦Rth1(550)≦−50 nm (8a)
120 nm ≤ Re2(550) ≤ 140 nm (9a)
50nm≦Rth2(550)≦80nm (10a)

Although the thicknesses of the first optical compensation layer and the second optical compensation layer are not particularly limited, they can usually range from 0.1 μm to 10 μm.

The first optical compensation layer and the second optical compensation layer may be directly laminated to each other, or may be laminated via an adhesive layer. As the adhesive, the same adhesive as used for bonding the polarizing element and the protective film can be used.

The polarizing plate and the retardation film can be adhered using the same adhesive layer as used for adhering the polarizing element and the protective film, but it is preferable to use an active energy ray-curable adhesive. By bonding with the same adhesive as the adhesive used for bonding the polarizing element and the protective film described above or with an active energy ray-curable adhesive, the optical compensation layer is supported by a relatively hard layer, thereby suppressing deformation. , Scratches and dents during transportation can be suppressed, which is preferable.

When the polarizing plate has a protective film only on one side of the polarizing element, the retardation film can be directly laminated on the polarizing element, but the polarizing plate has protective films on both sides of the polarizing element. In this case, the protective film between the polarizing element and the retardation film is preferably an optically isotropic film.

An optically isotropic film is one that satisfies the following formulas (11) and (12).
0 nm ≤ |Re3(590)| ≤ 20 nm (11)
0 nm ≤ |Rth3(590)| ≤ 20 nm (12)

Here, when the refractive index in the in-plane slow axis direction of the optically isotropic film is nx3, the refractive index in the in-plane fast axis direction is ny3, and the refractive index in the thickness direction is nz3, Re3(λ )=(nx3−ny3)×d3, Rth3(λ)={(nx3+ny3)/2−nz3}×d3, where d3 represents the thickness of the optically isotropic film.

There are no particular restrictions on the material, production method, etc. of the optically isotropic film, as long as it satisfies the above optical properties. The optically isotropic film may be a single optical film or a laminate of two or more optical films. Preferably, the optically isotropic film is a single film. This is because the contraction stress of the polarizing element and the occurrence of birefringence and unevenness due to the heat of the light source can be reduced, and the thickness of the liquid crystal panel can be reduced.

As the optical film used for the optically isotropic film, a film which is excellent in transparency, mechanical strength, thermal stability, moisture shielding property, and the like, and which hardly causes optical unevenness due to strain is preferably used. A polymer film is preferably used as the film.

The absolute value of the photoelastic coefficient of the optical film used for the optically isotropic film is preferably 1.0×10 ⁻¹⁰ m ² /N or less, and 5.0×10 ⁻¹¹ m ² /N or less. is more preferably 1.0×10 ⁻¹¹ m ² /N or less, and particularly preferably 5.0×10 ⁻¹² m ² /N or less. By setting the value of the photoelastic coefficient within the above range, it is possible to obtain a liquid crystal display device which is excellent in optical uniformity, has little change in optical properties even in environments such as high temperature and high humidity, and has excellent durability. can. Although the lower limit of the photoelastic coefficient is not particularly limited, it is generally 5.0×10 ⁻¹³ m ² /N or more.

Materials constituting the optically isotropic film include polycarbonate-based resins, polyvinyl alcohol-based resins, cellulose-based resins, polyester-based resins, polyarylate-based resins, polyimide-based resins, cyclic polyolefin-based resins, polysulfone-based resins, poly Ethersulfone-based resins, polyolefin-based resins, polystyrene-based resins, polyvinyl alcohol-based resins, and mixtures thereof can be used. In addition, thermosetting resins such as urethane, acrylic urethane, epoxy, and silicone or ultraviolet curable resins can also be used. The optically isotropic film may contain one or more of any appropriate additives.

As the cellulose-based resin, an ester of cellulose and fatty acid is preferable. Specific examples of such cellulose ester resins include triacetyl cellulose, diacetyl cellulose, tripropionyl cellulose, and dipropionyl cellulose. Among these, triacetyl cellulose is particularly preferred. Many products of triacetyl cellulose are commercially available, and it is also advantageous in terms of availability and cost. Triacetyl cellulose often has a retardation in the thickness direction (Rth) of more than 10 nm. , a cellulose resin film having a small retardation in the thickness direction can be obtained. As the method of forming the film, for example, a substrate film such as polyethylene terephthalate, polypropylene, stainless steel, etc. coated with a solvent such as cyclopentanone, methyl ethyl ketone, etc. is laminated to a general cellulose film, and dried by heating (for example, 80 3 minutes or more and 150° C. or less for about 3 minutes or more and 10 minutes or less), a method of peeling off the base film; A method of coating a general cellulose-based resin film, heat-drying (for example, at 80° C. or higher and 150° C. or lower for about 3 minutes or more and 10 minutes or less), and then peeling off the coated film can be used.

As the cellulose resin film having a small retardation in the thickness direction, a fatty acid cellulose resin film having a controlled degree of fat substitution can be used. Generally used triacetyl cellulose has a degree of acetic acid substitution of about 2.8, and Rth can be reduced by preferably controlling the degree of acetic acid substitution to 1.8 or more and 2.7 or less. By adding a plasticizer such as dibutyl phthalate, p-toluenesulfonanilide, or acetyltriethyl citrate to the fatty acid-substituted cellulose resin, Rth can be controlled to be small. The amount of the plasticizer added is preferably 40 parts by weight or less, more preferably 1 part by weight or more and 20 parts by weight or less, and still more preferably 1 part by weight or more and 15 parts by weight or less with respect to 100 parts by weight of the fatty acid cellulose resin. .

Further, as an optically isotropic film, a thermoplastic resin having a substituted and/or unsubstituted imide group in a side chain described in JP-A-2001-343529 (WO01/37007) and the like, and a substituted and/or A polymer film containing a resin composition containing a thermoplastic resin having an unsubstituted phenyl and a nitrile group, JP 2000-230016, JP 2001-151814, JP 2002-120326, JP 2002-254544, JP-A-2005-146084, polymer film containing acrylic resin having a lactone ring structure described in JP-A-2006-171464, JP-A-2004-70290, JP-A-2004 -70296, JP 2004-163924, JP 2004-292812, JP 2005-314534, JP 2006-131898, JP 2006-206881, JP 2006-265532 JP, JP-A-2006-283013, JP-A-2006-299005, JP-A-2006-335902, etc. Acrylic having a structural unit of unsaturated carboxylic acid alkyl ester and a structural unit of glutaric anhydride Polymer film containing system resin, JP 2006-309033, JP 2006-317560, JP 2006-328329, JP 2006-328334, JP 2006-337491, JP A film or the like containing a thermoplastic resin having a glutarimide structure described in JP-A-2006-337492, JP-A-2006-337493, JP-A-2006-337569, etc. can also be used. These films have small front retardation and thickness direction retardation, and also have a small photoelastic coefficient. Since it is small, it is preferable in that it is excellent in humidification durability.

It is also preferable to use a cyclic polyolefin resin as the optically isotropic film. A specific example of the cyclic polyolefin-based resin is preferably a norbornene-based resin. Cyclic polyolefin-based resin is a general term for resins polymerized using cyclic olefins as polymerized units, and is described, for example, in JP-A-1-240517, JP-A-3-14882, and JP-A-3-122137. resins. Specific examples include ring-opening (co)polymers of cyclic olefins, addition polymers of cyclic olefins, cyclic olefins and α-olefins such as ethylene and propylene, and their copolymers (typically random copolymers), and graft polymers obtained by modifying these with unsaturated carboxylic acids or derivatives thereof, and hydrides thereof. Specific examples of cyclic olefins include norbornene-based monomers.

Various products are commercially available as cyclic polyolefin resins. Specific examples include the trade name “Zeonor” manufactured by Nippon Zeon Co., Ltd., the trade name “Arton” manufactured by JSR Corporation, the trade name “Topas” manufactured by TICONA, and the trade name “Appel” manufactured by Mitsui Chemicals, Inc. mentioned.

A surface protection film may be laminated on the surface of the optical layered body opposite to the pressure-sensitive adhesive for the purpose of protecting the surface of the optical member from scratches and stains. The surface protective film is generally peeled off after the optical member has been attached to the liquid crystal cell or the like.

Examples of substrates for the surface protective film include polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; fluorinated polyolefin resins such as polyvinyl fluoride, polyvinylidene fluoride, and polyethylene fluoride; polyethylene naphthate, polyethylene Polyester resins such as terephthalate, polybutylene terephthalate, polyethylene terephthalate/isophthalate copolymer; polyamides such as nylon 6 and nylon 6,6; polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate Copolymers, ethylene-vinyl alcohol copolymers, polyvinyl alcohol, vinyl polymers such as vinylon; cellulose resins such as triacetyl cellulose, diacetyl cellulose, cellophane; polymethyl methacrylate, polyethyl methacrylate, polyacryl (Meth)acrylic resins such as ethyl acetate and polybutyl acrylate; other examples include polystyrene, polycarbonate, polyarylate, and polyimide. As the surface protective film, a film obtained by providing an adhesive layer on these substrates is used.

When the optical laminate is a polarizing plate with an adhesive layer, a test piece prepared by cutting the polarizing plate with an adhesive layer into a width of 25 mm was pulled at an angle of 180° C. at a speed of 10000 mm/min, and the end of the test piece was pulled. The peel force of the pressure-sensitive adhesive layer to the release film (hereinafter also referred to as separator peel force) measured when the release film is peeled can be less than 0.10 N.

When the optical laminate is a polarizing plate with an adhesive layer, the release film is peeled off from the polarizing plate with an adhesive layer, the surface of the adhesive layer subjected to corona treatment and the surface of the PET film subjected to corona treatment are attached, Furthermore, a test piece prepared by cutting it to a width of 25 mm was pulled at an angle of 180° C. at a speed of 300 mm/min at the end of the test piece, and the adhesive residue surface was observed when the PET film was peeled off from the polarizing plate with the adhesive layer. The state of the pressure-sensitive adhesive layer (adhesion to the substrate) can be cohesive failure.

When the optical laminate is a polarizing plate with an adhesive layer, cut the polarizing plate with an adhesive layer with a clicker, check the appearance of the prepared test piece from the separator surface, and observe wrinkles around the edge. The number of wrinkles to be counted may be 9 or less, preferably 0.

FIG. 1 shows an example of the layer structure of an optical layered body. The optical laminate 10 shown in FIG. 1 has an optical member 11, an adhesive layer 12, and a release film 13 in this order.

FIG. 2 shows an example of the layer structure of the pressure-sensitive adhesive layer-attached polarizing plate. The adhesive layer-attached polarizing plate 20 shown in FIG. 2 has a linear polarizing plate 21, an adhesive layer 22, and a release film 23 in this order, and the linear polarizing plate 21 includes a protective film 24 and a polarizer 25. have.

The present invention will be described in more detail below with reference to examples. Unless otherwise specified, "%" and "parts" in the examples are % by mass and parts by mass.

[Evaluation of Separator Peeling Force]
The pressure-sensitive adhesive layer-attached polarizing plates obtained in Examples and Comparative Examples were cut to a width of 25 mm to prepare test pieces. The end of the test piece was pulled at an angle of 180° C. at a speed of 10000 mm/min, and the separator peeling force was measured when the separator was peeled off. The evaluation criteria for separator peel strength are shown below.
A: Less than 0.10N B: 0.10N or more and less than 0.11N C: 0.11N or more

[Base material adhesion evaluation]
The release film was peeled off from the pressure-sensitive adhesive layer-attached polarizing plates obtained in Examples and Comparative Examples, and the pressure-sensitive adhesive layer was subjected to corona treatment. Next, a PET film was prepared and one surface of the PET film was subjected to corona treatment. The corona-treated surfaces of the pressure-sensitive adhesive layer and the PET film were bonded together and cut into a width of 25 mm to prepare a test piece. The edge of the test piece was pulled at an angle of 180° C. and a speed of 300 mm/min to peel the PET film from the polarizing plate. After peeling, the adhesive residue surface was observed. Evaluation criteria for substrate adhesion are shown below.
A: Cohesive failure of the adhesive B: Partial adhesive residue on the polarizing plate side C: No adhesive residue on the polarizing plate side

[Evaluation of cut wrinkles]
The pressure-sensitive adhesive layer-attached polarizing plates obtained in Examples and Comparative Examples were cut with a clicker to prepare test pieces. The appearance was confirmed from the separator surface side, cut wrinkles were observed around the edge, and the number of generated cut wrinkles was counted. Criteria for evaluation of cut wrinkles are shown below.
A: Number of cut wrinkles: 0 B: Number of cut wrinkles: 1 to 9 C: Number of cut wrinkles: 10 or more

[Preparation of acrylic polymer]
98.4 parts by mass of n-butyl acrylate, 1.0 part by mass of 2-hydroxyethyl acrylate, and 0.6 parts by mass of acrylic acid were placed in a reaction vessel equipped with a cooling tube, a nitrogen inlet tube, a thermometer and a stirrer. A solution obtained by mixing the body with 81.8 parts by mass of ethyl acetate was charged. After replacing the air in the reaction vessel with nitrogen gas, the internal temperature was adjusted to 60°C. Then, a solution of 0.12 parts of azobisisobutyronitrile dissolved in 10 parts of ethyl acetate was added. After maintaining the internal temperature at 54 to 56 ° C. until 12 hours have passed since the addition of azobisisobutyronitrile, ethyl acetate was added to adjust the polymer concentration to 20%. An ethyl acetate solution of the system polymer was prepared.

The weight average molecular weight (Mw) and number average molecular weight (Mn) of the obtained acrylic polymer were measured. For Mw and Mn, four columns of "TSKgel XL" manufactured by Tosoh Corporation and one column of "Shodex GPC KF-802" manufactured by Showa Denko K.K. and sold by Shoko Tsusho K.K. A total of 5 tubes were connected in series, and tetrahydrofuran was used as the eluent, and the sample concentration was 5 mg/mL, the sample introduction amount was 100 μL, the temperature was 40° C., and the flow rate was 1 mL/min. The acrylic polymer had a weight average molecular weight Mw of 1,180,000 and a number average molecular weight Mn of 54,000.

<Example 1>
[Preparation of adhesive composition]
For 100 parts by mass of the solid content of the acrylic polymer prepared as described above, an isocyanate cross-linking agent [ethyl acetate solution of trimethylolpropane adduct of tolylene diisocyanate (solid content concentration 75%), "Coronate L" (trade name) , manufactured by Tosoh Corporation] 0.136 parts by mass, 0.207 parts by mass of a silane coupling agent [trade name "KBM-403" obtained from Shin-Etsu Chemical Co., Ltd.] and the components described in Table 1 below. was prepared by

[Preparation of polarizing plate with adhesive layer]
The solutions of the acrylic pressure-sensitive adhesive compositions obtained in Examples and Comparative Examples were applied to a release film made of a polyethylene terephthalate film subjected to a release treatment [trade name (MRV38 (V04) obtained from Mitsubishi Plastics Co., Ltd.) )] was applied to the release-treated surface. Drying was performed at 90° C. for 3 minutes to form an adhesive layer on the surface of the separator film. After the adhesive layer was dried, it was transferred to the surface of the transparent protective film of the polarizing plate to prepare a polarizing plate with an adhesive layer. The pressure-sensitive adhesive layer-attached polarizing plate obtained was cured in an environment of 23° C. and 50% for 7 days, and then evaluated for separator peel strength, substrate adhesion and cut wrinkles. Table 1 shows the results.

<Examples 2 to 12, Comparative Examples 1 to 4>
A polarizing plate with an adhesive layer was produced in the same manner as in Example 1, except that the components shown in Table 1 were used in place of the components used in the preparation of the adhesive composition in Example 1. Table 1 shows the results.

Details of the abbreviations in Table 1 are as follows.
[Non-reactive silicone oil]
A1: Side chain type long-chain alkyl-modified silicone oil, trade name “KF-4003” obtained from Shin-Etsu Chemical Co., Ltd.
A2: Side chain type long-chain alkyl-modified silicone oil, trade name “KF-4917” obtained from Shin-Etsu Chemical Co., Ltd.
[Reactive silicone oil]
B1: Side chain type diamine-modified silicone oil, trade name "KF-859" obtained from Shin-Etsu Chemical Co., Ltd.
B2: Side chain type diamine-modified silicone oil, trade name "KF-8005" obtained from Shin-Etsu Chemical Co., Ltd.

10, 20 optical laminate, 11, 21 optical member, 12, 22 adhesive layer, 13, 23 release film, 24 protective film, 25 polarizer.

Claims (7)

A pressure-sensitive adhesive composition comprising a (meth)acrylic resin, a cross-linking agent, a reactive silicone oil, and a non-reactive silicone oil. The reactive silicone oil contains a reactive silicone oil having an amino group on the side chain of the polysiloxane skeleton,
The pressure-sensitive adhesive composition according to claim 1, wherein the non-reactive silicone oil contains a non-reactive silicone oil having an alkyl group on the side chain of the polysiloxane skeleton. 3. The pressure-sensitive adhesive composition according to claim 2, wherein said amino group is a group derived from diamine. 3. The pressure-sensitive adhesive composition according to claim 2, wherein said alkyl group is at least one selected from the group consisting of long-chain alkyl groups and fluoroalkyl groups. The adhesive composition according to any one of claims 1 to 4, further comprising a silane coupling agent. A pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to any one of claims 1 to 5. An optical laminate comprising an optical member, the pressure-sensitive adhesive layer according to claim 6, and a release film in this order.

Images