KR101796142B1 - adhesion composition, adhesive, and adhesion sheet - Google Patents

Abstract

A pressure sensitive adhesive composition excellent in both light leakage and durability when applied to an optical member such as a polarizing plate, a process for producing the pressure sensitive adhesive composition, a pressure sensitive adhesive and a pressure sensitive adhesive sheet are provided.
(Meth) acrylic acid ester copolymer (A) having a weight average molecular weight of 700,000 to 2,550,000, a second (meth) acrylic acid ester copolymer (B) having a weight average molecular weight of 8000 to 250,000 and a crosslinking agent Acrylic acid ester copolymer (B) in an amount of 5 to 50 parts by mass based on 100 parts by mass of the first (meth) acrylic acid ester copolymer (A), the second (meth) acrylic acid ester copolymer The ester copolymer (B) contains a monomer having a functional group (b1) having a high reactivity with the crosslinking agent (C) as a constituent component, and the ratio of the monomer to the second (meth) acrylic acid ester copolymer (B) (Meth) acrylic acid ester copolymer (A) does not contain a monomer having a functional group reactive with the crosslinking agent (C) as a constituent component, and the second (meth) acrylic acid ester copolymer The functional group (b1) of the ester copolymer (B) Viscous composition containing a monomer reactive with the cross-linking agent (C) having a low functional group (a1) as a component.

Description

Adhesive compositions, adhesives, and adhesion sheets,

The present invention relates to a pressure-sensitive adhesive composition, a method for producing a pressure-sensitive adhesive composition, a pressure-sensitive adhesive (a material obtained by crosslinking a pressure-sensitive adhesive composition) and a pressure-sensitive adhesive sheet, and more particularly to a pressure-sensitive adhesive composition suitable for an optical member such as a polarizing plate, Sheet.

Generally, in a liquid crystal panel, a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition is often used to adhere a polarizing plate or a retardation plate to a glass substrate or the like. However, since the optical member such as the polarizing plate and the retarder is easily shrunk due to heat or the like, contraction occurs due to thermal history, and as a result, the pressure-sensitive adhesive layer laminated on the optical member can not follow shrinkage thereof, (So-called whiteness) due to the deviation of the optical axis of the optical member due to the stress at the time of shrinkage of the optical member.

(1) a method of suppressing shrinkage of an optical member by bonding a pressure-sensitive adhesive layer having a high adhesive force and excellent in shape stability to an optical member such as a polarizing plate, or (2) And a pressure-sensitive adhesive layer having a small stress at the time of shrinkage is used. As the method (1), it is effective to use a pressure-sensitive adhesive layer having a high storage modulus as shown in Patent Document 1. [ On the other hand, in the method (2), it is effective to use a pressure-sensitive adhesive layer excellent in stress relaxation property capable of flexibly deformation. However, conventionally, when the pressure-sensitive adhesive layer having excellent stress relaxation property is to be formed, it is necessary to make the pressure-sensitive adhesive layer to have a very low crosslinking density. In this case, the strength of the pressure-sensitive adhesive layer itself is lowered, and the durability is deteriorated.

Thus, in Patent Documents 2 to 4, the pressure-sensitive adhesive composition obtained is appropriately softened by adding a plasticizer, liquid paraffin, urethane elastomer or the like to the acrylic pressure-sensitive adhesive instead of making the crosslink density of the pressure-sensitive adhesive layer very low, To thereby obtain a light leakage property and a durability.

Patent Document 1: Japanese Patent Application Laid-Open No. 2006-235568 Patent Document 2: Japanese Patent Application Laid-Open No. 5-45517 Patent Document 3: JP-A-9-137143 Patent Document 4: Japanese Patent Application Laid-Open No. 2005-194366

However, in the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition to which the plasticizer or liquid paraffin is added, plasticizers and liquid paraffin escape with time, and the liquid crystal cell is contaminated. Further, in the pressure-sensitive adhesive composition to which the urethane elastomer is added, the amount of the urethane elastomer to be added is limited from the viewpoint of compatibility with other components. Therefore, the improvement of the stress relaxation property is insufficient, and depending on the compatibility of the acrylic pressure- . Thus, in the prior art, it is difficult to fundamentally improve the light-leak resistance and durability of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition for optical members.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances and aims to provide a sticky composition excellent in both light leakage and durability when applied to an optical member such as a polarizing plate and a method for producing the sticky composition and a pressure- do.

(Meth) acrylic acid ester copolymer (A) having a weight average molecular weight of 700000 to 250000 and a second (meth) acrylic acid ester copolymer (A) having a weight average molecular weight of 8000 to 250000. In order to achieve the above object, (B) relative to 100 parts by mass of the first (meth) acrylic acid ester copolymer (A) and the second (meth) acrylic acid ester copolymer (B) containing the ester copolymer Wherein the second (meth) acrylic acid ester copolymer (B) contains a monomer having a functional group (b1) having a high reactivity with the crosslinking agent (C) as a constituent component, and the second (A) is a copolymer in which the proportion of the monomer is greater than 1 mass% in the second (meth) acrylic acid ester copolymer (B), and the first (meth) acrylic acid ester copolymer A monomer having a functional group as a constituent (A1) having a lower reactivity with the crosslinking agent (C) than the functional group (b1) of the second (meth) acrylic acid ester copolymer (B) as a constituent component Thereby providing a sticky composition (Invention 1).

In the pressure-sensitive adhesive in which the pressure-sensitive adhesive composition according to the invention (invention 1) is crosslinked, a three-dimensional network structure by crosslinking is formed on the low molecular weight copolymer (B) conventionally used as a plasticizer, The high molecular weight copolymer (A) which is not crosslinked is entangled to exert excellent stress relaxation property. When the pressure-sensitive adhesive having excellent stress relaxation property is used, it is possible to obtain a pressure-sensitive adhesive sheet excellent in both leakage of light and durability when applied to an optical member such as a polarizing plate.

In the above invention (Invention 1), it is preferable that the first (meth) acrylic acid ester copolymer (A) does not contain a monomer having a functional group having high reactivity with the crosslinking agent (C) as a constituent component (invention 2) .

In the above invention (Invention 1 or 2), the functional group (a1) having low reactivity with the crosslinking agent (C) in the first (meth) acrylic acid ester copolymer (A) is a carboxyl group, The functional group (b1) having high reactivity with the crosslinking agent (C) in the ester copolymer (B) is a hydroxyl group, and the crosslinking agent (C) is preferably an isocyanate crosslinking agent (invention 3).

In the above invention (Invention 3), it is preferable that the first (meth) acrylic acid ester copolymer (A) contains 0 to 15 mass% of a carboxyl group-containing monomer as the monomer unit constituting the copolymer ). The pressure-sensitive adhesive sheet thus obtained is excellent in reworkability.

In the above invention (invention 3, 4), it is preferable that the second (meth) acrylic acid ester copolymer (B) contains 3 to 40 mass% of a hydroxyl group-containing monomer as the monomer unit constituting the copolymer Invention 5). The pressure-sensitive adhesive sheet thus obtained is more excellent in durability.

In the invention (Invention 3 to 5), the content of the isocyanate crosslinking agent is preferably such that the isocyanate group of the isocyanate crosslinking agent is a functional group having a high reactivity with the crosslinking agent (C) in the second (meth) acrylic acid ester copolymer (B) is preferably 0.1 to 5 equivalents relative to the amount of the component (b1) (invention 6).

In the above inventions (inventions 1 to 6), it is preferable to further contain a silane coupling agent (D) (invention 7).

In the invention (Invention 7), the content of the silane coupling agent (D) is preferably 0.05 to 0.5 part by mass with respect to 100 parts by mass of the first (meth) acrylic acid ester copolymer (A).

A second aspect of the present invention is a method for producing the adhesive composition (inventions 1 to 6), wherein the monomer constituting the first (meth) acrylic ester copolymer (A) is subjected to radical polymerization at a conversion of 50 to 90% (1) comprising the steps of: (1) preparing a first (meth) acrylic ester copolymer (A); and adding a monomer remaining during polymerization of the first (meth) acrylic acid ester copolymer Acrylate copolymer (B) by radical-copolymerizing a monomer having a highly reactive functional group (b1) in the presence of the first (meth) acrylic acid ester copolymer (A) 2) and the step (3) of adding the crosslinking agent (C) (Invention 9).

In the invention (Invention 9), it is preferable that in the step (2) of producing the second (meth) acrylic acid ester copolymer (B), the amount of the (meth) acrylic acid ester copolymer It is preferable that the monomer having a functional group (b1) having high reactivity with the crosslinking agent (C) is subjected to radical copolymerization at a conversion of 70 to 100% (Invention 10).

In the invention (Invention 9, 10), when the adhesive composition (Invention 7 or 8) is produced, the step of adding the silane coupling agent (D) is further included.

The third invention provides a pressure-sensitive adhesive obtained by crosslinking the adhesive compositions (inventions 1 to 8) (invention 12).

A fourth aspect of the present invention provides a pressure-sensitive adhesive sheet comprising a substrate and a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer comprises the pressure-sensitive adhesive (invention 12).

In the invention (invention 13), it is preferable that the substrate is an optical member (invention 14).

A fifth aspect of the present invention is a pressure sensitive adhesive sheet comprising two release sheets and a pressure sensitive adhesive layer sandwiched between the release sheets so as to contact the release surfaces of the two release sheets, wherein the pressure sensitive adhesive layer is the pressure sensitive adhesive (invention 12) (Invention 15).

In the pressure-sensitive adhesive in which the pressure-sensitive adhesive composition according to the present invention is crosslinked, a three-dimensional network structure is formed by cross-linking on a low molecular weight copolymer conventionally used as a plasticizer, and a high molecular weight By entangling the copolymer, excellent stress relaxation properties are exhibited. When the pressure-sensitive adhesive having excellent stress relaxation property is used, a pressure-sensitive adhesive sheet excellent in both leakage of light and durability can be obtained when the pressure-sensitive adhesive is applied to an optical member such as a polarizing plate.

1 is a cross-sectional view of a pressure-sensitive adhesive sheet according to a first embodiment of the present invention.
2 is a cross-sectional view of a pressure-sensitive adhesive sheet according to a second embodiment of the present invention.
3 is a view showing a measurement area of a light leakage test in a polarizing plate with a pressure-sensitive adhesive layer.

Hereinafter, embodiments of the present invention will be described.

[Adhesive composition]

The adhesive composition according to the present embodiment is a composition comprising a first (meth) acrylic acid ester copolymer (A) having a weight average molecular weight of 700,000 to 2.5 million and a second (meth) acrylic acid ester copolymer having a weight average molecular weight of 8000 to 250,000 B) and a cross-linking agent (C), and preferably further contains a silane coupling agent (D). In the present specification, the term "(meth) acrylic acid ester" means both of an acrylic acid ester and a methacrylic acid ester. The same is true of other similar terms.

The second (meth) acrylic acid ester copolymer (B) comprises a monomer having a functional group (b1) highly reactive with the crosslinking agent (C) as a constituent component, and the constituent ratio of the monomer (B) %.

On the other hand, the first (meth) acrylic acid ester copolymer (A) does not contain a monomer having a functional group reactive with the crosslinking agent (C) as a constitutional unit, or the second (meth) acrylic acid ester copolymer And a monomer having a functional group (a1) having a lower reactivity with the crosslinking agent (C) than the above-mentioned functional group (b1).

The (meth) acrylic acid ester copolymer (A) or (B) is obtained by copolymerizing a (meth) acrylic acid ester having an alkyl group of an alkyl group of an ester moiety of 1 to 20, a monomer having a reactive functional group (monomer having a reactive functional group) Copolymers with other monomers used are preferred. It is also preferable that the first (meth) acrylic acid ester copolymer (A) does not contain the above-mentioned reactive functional group-containing monomer as a constitutional unit.

Examples of the (meth) acrylic esters having 1 to 20 carbon atoms in the alkyl moiety of the ester moiety include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) (Meth) acrylate, dodecyl (meth) acrylate, myristyl (meth) acrylate, isobutyl (meth) acrylate, isobutyl , Palmityl (meth) acrylate, stearyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.

Examples of the reactive functional group-containing monomer include monomers having a hydroxyl group in the molecule (hydroxyl group-containing monomers), monomers having a carboxyl group in the molecule (carboxyl group-containing monomers), and monomers having an amino group in the molecule (amino group-containing monomers) have.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (Meth) acrylate, 3-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. These may be used alone or in combination of two or more.

Examples of the carboxyl group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, citraconic acid and vinyl acetate. These may be used alone or in combination of two or more.

Examples of the amino group-containing monomer include aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, . These may be used alone or in combination of two or more.

Examples of the other monomer include (meth) acrylic acid esters having an aliphatic ring such as (meth) acrylic acid cyclohexyl, (meth) acrylic acid esters having an aromatic ring such as phenyl (meth) acrylate, Acrylamide, non-crosslinked acrylamide such as acrylamide, and acrylamide, and styrene. These may be used alone or in combination of two or more.

The selection of the monomer containing a reactive functional group (a1) used in the first (meth) acrylic acid ester copolymer (A) and the reactive functional group (b1) used in the second (meth) acrylic acid ester copolymer (B) , And the reactivity with the crosslinking agent (C) to be used. Details will be described later.

Here, the second (meth) acrylic acid ester copolymer (B) contains 1% by mass or more of the monomer containing the reactive functional group (b1), and the upper limit thereof is usually 50% by mass. Preferably, the monomer contains the reactive functional group (b1) -containing monomer in an amount of 3 to 40 mass%, particularly preferably 5 to 25 mass%. The degree of crosslinking of the second (meth) acrylic acid ester copolymer (B) is favorable by containing the reactive functional group (b1) -containing monomer within the above range. In combination with the first (meth) acrylic acid ester copolymer (A) The resulting pressure-sensitive adhesive exhibits excellent stress relaxation properties. When the content of the reactive functional group (b1) -containing monomer is 1% by mass or less, the crosslinking of the second (meth) acrylic acid ester copolymer (B) is not sufficient and the durability is accordingly lowered. On the other hand, if the content of the reactive functional group (b1) -containing monomer exceeds 50% by mass, the crosslinking of the second (meth) acrylic acid ester copolymer (B) becomes excessive and the compatibility with the adherend There is a concern. When the upper limit of the content of the reactive functional group (b1) -containing monomer is 40 mass%, the resulting pressure-sensitive adhesive sheet has better durability.

In the present embodiment, the second (meth) acrylic ester-based copolymer (B) may be used singly or in combination of two or more.

The weight average molecular weight of the second (meth) acrylic acid ester copolymer (B) is 8000 to 250,000, preferably 20,000 to 150,000. That is, the second (meth) acrylic acid ester copolymer (B) is a low molecular weight polymer component. In the present specification, the weight average molecular weight is a polystyrene reduced value measured by a gel permeation chromatography (GPC) method.

Since the weight average molecular weight of the second (meth) acrylic acid ester copolymer (B) is within the above range, a three-dimensional network structure peculiar to the adhesive composition according to the present embodiment is formed, contributing to excellent stress relaxation properties. That is, when the weight average molecular weight of the second (meth) acrylic acid ester copolymer (B) is less than 8000, a satisfactory three-dimensional network structure can not be obtained. On the other hand, when the weight average molecular weight of the second (meth) acrylic acid ester copolymer (B) exceeds 25,000, the compatibility is lowered and the copolymer (A) and the copolymer (B) , It is difficult to form a peculiar network structure for the purpose, resulting in poor durability and reworkability.

The first (meth) acrylic acid ester copolymer (A) does not contain a monomer having a functional group reactive with the crosslinking agent (C) as a constituent, and the functional group (b1 (A1) having a lower reactivity with the crosslinking agent (C) than the crosslinking agent (C), and preferably does not contain a monomer having a functional group having high reactivity with the crosslinking agent (C) as a constituent component.

The first (meth) acrylic acid ester copolymer (A) may contain no monomer having a functional group reactive with the crosslinking agent (C), but the first functional group (b1) of the second (meth) acrylic acid ester copolymer When the monomer having the reactive functional group (a1) having low reactivity is contained, the reaction between the second (meth) acrylic acid ester copolymer (B) and the crosslinking agent (C) is promoted, or when the silane coupling agent (D) , The reactive functional group (a1) of the first (meth) acrylic acid ester copolymer (A) reacts with the alkoxysilyl group or the like of the silane coupling agent (D) and the degree of aggregation of the first (meth) It is possible to obtain desired adhesiveness, which is preferable.

When the first (meth) acrylic acid ester copolymer (A) contains the above-mentioned reactive functional group (a1) containing monomer, its content is usually 20 mass% or less, preferably 15 mass% or less, more preferably 10 mass% desirable. If the content of the reactive functional group (a1) -containing monomer exceeds 20 mass%, the first (meth) acrylic acid ester copolymer (A) may agglomerate too much and the desired stress relaxation property may not be obtained. From the viewpoint of reworkability, the content of the reactive functional group (a1) -containing monomer is preferably 15% by mass or less.

The first (meth) acrylic acid ester copolymer (A) contains a monomer having a functional group having a reactivity with the crosslinking agent (C) equal to or higher than that of the reactive functional group (b1) of the second (meth) acrylic acid ester copolymer However, when contained, the content of the monomer having the functional group in the molecule is preferably 1% by mass or less, more preferably 0.5% by mass or less, in the copolymer (A). If the content of the monomer exceeds 1% by mass, there is a fear that the reaction between the second (meth) acrylic acid ester copolymer (B) to be reacted with the cross-linking agent (C)

In the present embodiment, the first (meth) acrylic acid ester copolymer (A) may be used singly or in combination of two or more kinds.

The weight average molecular weight of the first (meth) acrylic acid ester copolymer (A) is from 700,000 to 250,000, preferably from 1 million to 2,000,000. That is, the first (meth) acrylic acid ester copolymer (A) is a high molecular weight polymer component.

When the weight average molecular weight of the first (meth) acrylic acid ester copolymer (A) is within the above range, the first (meth) acrylic acid ester copolymer (B) The ester copolymer (A) is satisfactorily entangled, contributes to excellent stress relaxation property, and adhesion with an adherend and sufficient adhesion durability under high temperature and wet heat conditions are sufficient, whereby swelling, peeling, and the like can be prevented .

If the weight-average molecular weight of the first (meth) acrylic acid ester copolymer (A) is less than 700,000, the cohesive force of the component (A) is lowered and the durability and reworkability may deteriorate. When the weight average molecular weight of the first (meth) acrylic acid ester copolymer (A) is more than 250,000, the obtained pressure sensitive adhesive becomes too hard, and the desired stress relaxation property may not be obtained.

The proportion of the second (meth) acrylic acid ester copolymer (B) relative to 100 parts by mass of the first (meth) acrylic acid ester copolymer (A) is 5 to 50 parts by mass, preferably 10 to 30 parts by mass.

(A) and the second (meth) acrylic acid ester copolymer (B) in the above ratio, the pressure-sensitive adhesive composition of the second (meth) acrylic acid ester copolymer (B) (Meth) acrylic ester copolymer (A) (high molecular weight polymer) which is not crosslinked is entangled with the three-dimensional network structure through a crosslinking agent (C) , Excellent stress relaxation properties are exhibited. In addition, since the strength of the obtained pressure-sensitive adhesive is maintained by the presence of the three-dimensional network structure, durability is enhanced.

Examples of the crosslinking agent (C) include an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, and a metal chelating crosslinking agent.

The isocyanate-based crosslinking agent includes at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as trilene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane di Alicyclic polyisocyanates such as isocyanate and the like, and reaction products thereof with a low molecular active hydrogen-containing compound such as a non-isomer, an isocyanurate, furthermore ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, And duct bodies. These may be used singly or in combination of two or more kinds.

Examples of the epoxy cross-linking agent include 1,3-bis (N, N'-diglycidylaminomethyl) cyclohexane, N, N, N ', N'-tetraglycidyl- Diamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylol propane diglycidyl ether, diglycidyl aniline, diglycidyl amine, and the like. These may be used singly or in combination of two or more kinds.

Examples of the aziridine crosslinking agent include diphenylmethane-4,4'-bis (1-aziridinecarbazide), trimethylolpropane tri- -aziridinylpropionate, tetramethylolmethane tri- Aziridinyl propionate, toluene-2,4-bis (1-aziridinecarbanide), triethylene melamine, bisisophthaloyl-1- (2-methyl aziridine), tris- Aziridine) phosphine, trimethylol propane tri- beta - {2-methyl aziridine) propionate, and the like. These may be used singly or in combination of two or more kinds.

Metal chelate-based crosslinking agents include metal chelate compounds such as aluminum, zirconium, titanium, zinc, iron and tin, but aluminum chelate compounds are preferable from the viewpoint of performance. Examples of the aluminum chelate compound include diisopropoxy aluminum monooleate acetoacetate, monoisopropoxy aluminum bisoleyl acetoacetate, monoisopropoxy aluminum monooleate monoethylacetoacetate, diisopropoxy aluminum mono Lauryl acetoacetate, diisopropoxyaluminum monostearyl acetoacetate, diisopropoxy aluminum monoisostearyl acetoacetate, and the like. These may be used singly or in combination of two or more kinds.

The content of the crosslinking agent (C) is preferably such that the crosslinkable group (for example, isocyanate group) of the crosslinking agent (C) is the reactive functional group (b1) (for example, hydroxyl group) of the second (meth) acrylic acid ester copolymer (B) The amount is preferably 0.1 to 5 equivalents, more preferably 0.2 to 3 equivalents. If the amount of the crosslinkable group is less than 0.1 equivalent, crosslinking may not be performed sufficiently. If the amount of the crosslinkable group exceeds 5 equivalents, the adhesive strength of the application may increase and the reworkability may decrease .

In the present embodiment, in addition to the crosslinking agent (C), other crosslinking agents (two or more kinds of crosslinking agents) exhibiting higher reactivity with the reactive functional group (a1) of the copolymer (A) than the reactive functional group When the crosslinking agent is used in combination, the other kind of crosslinking agent other than the crosslinking agent having the greatest amount of addition thereof) may be used in combination within a range not to impair the effect of the present invention. Specifically, when the reactive functional group (a1) of the copolymer (A) is a carboxyl group, the reactive functional group (b1) of the copolymer (B) is a hydroxyl group, and the crosslinking agent (C) is an isocyanate crosslinking agent, A small amount of a crosslinking agent can be added. The addition of such another crosslinking agent is effective when the copolymer (A) is not sufficiently entangled with the three-dimensional network structure constituted by the copolymer (B), and the cohesion is insufficient.

When other crosslinking agents are added, the addition amount thereof is preferably 0.01 to 1 part by mass relative to 100 parts by mass of the total of the copolymers (A) and (B).

When the crosslinking agent (C) is an isocyanate-based crosslinking agent, the copolymer (A) and the reactive functional group-containing monomer (B) (A1) -containing functional group (a1) is preferably a carboxyl group-containing monomer, and the reactive functional group (b1) -containing monomer of the copolymer (B) is preferably a hydroxyl group-containing monomer or an amino group-containing monomer.

On the other hand, when the crosslinking agent (C) is an epoxy crosslinking agent, an aziridine crosslinking agent or a metal chelating crosslinking agent, the reactive functional group (a1) -containing monomer of the copolymer (A) As the monomer containing (b1), a carboxyl group-containing monomer is preferably selected.

The flexibility of the bond formed between the crosslinking agent (C) and the copolymer (B) and the warming property of the crosslinking reaction and the reactivity of the copolymer (B) react appropriately with the silane coupling agent (D) (A) containing a reactive functional group (a1) of the copolymer (A) is reacted with a carboxyl group-containing monomer, a monomer containing a reactive functional group (b1) of the copolymer (B) Containing monomer is particularly preferable.

The adhesive composition according to the present embodiment preferably further contains a silane coupling agent (D). When the first (meth) acrylic ester copolymer (A) has a carboxyl group, the alkoxysilyl group of the silane coupling agent (D) and the first (meth) acrylic acid ester copolymer The degree of aggregation of the first (meth) acrylic acid ester copolymer (A) can be adjusted since the carboxyl group of the first (meth) acrylic acid ester copolymer (A) reacts. Further, when the polarizing plate is attached to a liquid crystal glass cell or the like, for example, the adhesion between the pressure-sensitive adhesive and the liquid crystal glass cell becomes better when the silane coupling agent (D) is contained.

The silane coupling agent (D) is preferably an organosilicon compound having at least one alkoxysilyl group in the molecule, which has good compatibility with the pressure-sensitive adhesive component and has optical transparency, for example, substantially transparent. The amount of the silane coupling agent (D) to be added is preferably 0.05 to 0.5 part by mass, more preferably 0.1 to 0.3 part by mass relative to 100 parts by mass of the first (meth) acrylic acid ester copolymer (A) .

Specific examples of the silane coupling agent (D) include a polymerizable unsaturated group-containing silicon compound such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxy Silane, silicon compounds having an epoxy structure such as 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) Amino group-containing silicon compounds such as methoxysilane and N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, and 3-chloropropyltrimethoxysilane. These may be used singly or in combination of two or more kinds.

Various additives commonly used in acrylic pressure sensitive adhesives such as a tackifier, an antioxidant, an ultraviolet absorber, a light stabilizer, a softening agent, a filler, an antistatic agent, a refractive index adjuster and the like may be added to the adhesive composition.

[Production method of adhesive composition]

The adhesive composition can be produced, for example, in the following manner.

That is, first, the (meth) acrylic acid ester copolymer (A) and the (B) are preferably separately prepared by a usual radical polymerization method in a polymerization solvent described later. Then, the obtained solution of both copolymers is mixed, and a diluting solvent is added so that the solid content concentration becomes 10 to 40 mass%. Finally, a crosslinking agent (C) and a silane coupling agent (D) are added sequentially and sufficiently mixed to obtain a sticky composition diluted in a solvent.

It is also preferable that the adhesive composition is produced by the following series polymerization.

Specifically,

(1) After the first (meth) acrylic acid ester copolymer (A) is prepared by radical polymerization of the monomer constituting the first (meth) acrylic acid ester copolymer (A) at a conversion of 50 to 90%

(2) A method for producing a thermosetting resin composition, which comprises reacting a monomer having a functional group (b1) having high reactivity with a crosslinking agent (C) and a monomer having a functional group which is left at the time of polymerization of the first (meth) Acrylic copolymer (B) is produced by radical copolymerization in the presence of the first (meth) acrylic ester copolymer (A), preferably at a conversion of 70 to 100%

(3) The crosslinking agent (C) and / or the silane coupling agent (D) (component (D) is added as desired).

The monomer constituting the first (meth) acrylic acid ester copolymer (A) in the step (1) is as described above, and preferably at least a (meth) acrylic acid ester Lt; / RTI > In this case, in the step (2), the monomer remaining in the polymerization of the first (meth) acrylic acid ester copolymer (A) corresponds to the (meth) acrylic acid ester in which the alkyl group of the ester moiety has 1 to 20 carbon atoms .

The above-mentioned series polymerization can be carried out by a solution polymerization method or the like using a polymerization initiator as desired. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, and methyl ethyl ketone, and two or more of them may be used in combination.

Examples of the polymerization initiator include an azo compound, an organic peroxide, and the like, and two or more of them may be used in combination. Examples of the azo based compound include azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane 1-carbo Azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2 'azobis (2,2'-azobis Azobis (2-methylpropionate), 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis (2-hydroxymethylpropionitrile) -Azobis [2- (2-imidazolin-2-yl) propane].

Examples of the organic peroxide include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di (2-ethoxyethyl) peroxydicarbonate , t-butyl peroxyneodecanoate, t-butyl peroxybibarate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, and diacetyl peroxide.

When both the crosslinking agent (C) and the silane coupling agent (D) are added in the step (3), the crosslinking agent (C) and the silane coupling agent (D) are each diluted with a solvent to a predetermined concentration, .

In the above-mentioned series polymerization, the proportion of the first (meth) acrylic acid ester copolymer (A) and the second (meth) acrylic acid ester copolymer (B) and the content of the functional group are within the above- Adjust the amount of monomer properly. The polymerization conditions are appropriately adjusted so that the weight average molecular weights of the first (meth) acrylic acid ester copolymer (A) and the second (meth) acrylic acid ester copolymer (B) fall within the above range.

[adhesive]

The pressure-sensitive adhesive according to the present embodiment is obtained by crosslinking the pressure-sensitive adhesive composition. The crosslinking of the adhesive composition can be carried out by heat treatment. This heating treatment may also be used in the drying treatment for volatilizing the diluting solvent and the like of the adhesive composition.

When the heat treatment is carried out, the heating temperature is preferably 50 to 150 ° C, more preferably 70 to 120 ° C. The heating time is preferably 30 seconds to 3 minutes, more preferably 50 seconds to 2 minutes. It is particularly preferable to leave a curing period of about 1 to 2 weeks at room temperature (for example, 23 DEG C, 50% RH) after the heat treatment.

The second (meth) acrylic acid ester copolymer (B) is crosslinked by the crosslinking agent (C) by the above heat treatment (and curing) to form a three-dimensional network structure, The (meth) acrylic acid ester copolymer (A) is not entangled directly with a direct chemical bond, or is entangled with a very small chemical bond. When the first (meth) acrylic acid ester copolymer (A) has a carboxyl group, the first (meth) acrylic acid ester copolymer (A) reacts with the silane coupling agent (D) to coagulate to a predetermined degree.

The pressure-sensitive adhesive described above can be preferably used for optical members, and is favorable for adhesion between a polarizing plate and a retardation plate, or adhesion between a polarizing plate (polarizing film) and a retardation plate (retardation film) and a glass substrate. Since the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive has a very excellent stress relaxation property, even if the dimensional change of the adherend is large, the pressure caused by the dimensional change can be absorbed and alleviated by the pressure- It is possible to effectively prevent light leakage when used in such an optical member. That is, the pressure sensitive adhesive according to the present embodiment achieves compatibility between light leakage and durability.

[Adhesive sheet]

1, the pressure-sensitive adhesive sheet 1A according to the first embodiment comprises a release sheet 12, a pressure-sensitive adhesive layer 11 laminated on the release surface of the release sheet 12, And a substrate 13 laminated on the pressure-sensitive adhesive layer 11. [

2, the pressure-sensitive adhesive sheet 1B according to the second embodiment comprises two sheets of the release sheets 12a and 12b and two sheets of the release sheets 12a and 12b so as to come into contact with the release surfaces of the two release sheets 12a and 12b. And a pressure-sensitive adhesive layer 11 sandwiched between the release sheets 12a and 12b. In the present specification, the release surface of the release sheet means a surface having release properties in the release sheet, and includes any of the surface subjected to the release treatment and the surface exhibiting the release property without performing the release treatment.

In either of the pressure-sensitive adhesive sheets 1A, 1B, the pressure-sensitive adhesive layer 11 becomes a pressure-sensitive adhesive which is obtained by crosslinking the above-mentioned pressure-sensitive adhesive composition.

The thickness of the pressure-sensitive adhesive layer 11 is appropriately determined according to the intended use of the pressure-sensitive adhesive sheets 1A and 1B, but is usually in the range of 5 to 100 占 퐉, preferably 10 to 60 占 퐉, It is preferably 10 to 50 占 퐉, more preferably 10 to 30 占 퐉.

The substrate 13 is not particularly limited, and any substrate that is used as a base sheet of a general adhesive sheet can be used. For example, woven or nonwoven fabrics using fibers such as rayon, acrylic, and polyester, as well as desired optical members; Papers such as high-quality paper, glazing paper, impregnated paper, and coated paper; Metal foil such as aluminum or copper; Foams such as urethane foams and polyethylene foams; Polyester films such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate, polyurethane films, polyethylene films, polypropylene films, polyvinyl chloride films, polyvinylidene chloride films, polyvinyl alcohol films, ethylene-vinyl acetate A plastic film such as a copolymer film, a polystyrene film, a polycarbonate film, an acrylic resin film, a norbornene resin film, and a cycloolefin resin film; And a laminate of two or more kinds thereof. The plastic film may be uniaxially or biaxially stretched.

Examples of the optical member include a polarizing plate (polarizing film), a polarizer, a retardation film (phase difference film), a viewing angle compensating film, a luminance improving film, and a contrast enhancing film. Among them, the polarizing plate (polarizing film) is easy to shrink and has a large dimensional change, so that it is suitable as an object for forming the pressure-sensitive adhesive layer 11 from the viewpoint of light-leak resistance.

The thickness of the base material 13 varies depending on the kind thereof, but is usually 10 to 500 占 퐉, preferably 50 to 300 占 퐉, for example in the case of optical members.

Examples of the release sheets 12, 12a and 12b include a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, a polyethylene terephthalate film, An ethylene / (meth) acrylic acid copolymer film, an ethylene / (meth) acrylic acid ester copolymer film, a polystyrene film, a polyethylene naphthalate film, a polybutylene terephthalate film, a polyurethane film, , A polycarbonate film, a polyimide film, a fluororesin film, a liquid crystal polymer film and the like are used. These crosslinked films are also used. Alternatively, these laminated films may be used.

It is preferable that a peeling treatment is performed on the peeling surface of the peeling sheet (in particular, the surface in contact with the peeling layer 11). Examples of the releasing agent used in the peeling treatment include an alkyd type, a silicone type, a fluorine type, an unsaturated polyester type, a polyolefin type, and a wax type releasing agent.

The thickness of the release sheets 12, 12a, 12b is not particularly limited, but is usually about 20 to 150 占 퐉.

In order to produce the pressure-sensitive adhesive sheet 1A, a solution containing the pressure-sensitive adhesive composition is coated on the release surface of the release sheet 12 and heat treatment is performed to form the pressure-sensitive adhesive layer 11, 11, a substrate 13 is laminated. The conditions of the heat treatment are as described above.

In order to produce the pressure-sensitive adhesive sheet 1B, a coating solution containing the pressure-sensitive adhesive composition is applied to the release surface of one release sheet 12a (or 12b), and the pressure- The release face of the other release sheet 12b (or 12a) is covered with the pressure-sensitive adhesive layer 11.

Examples of the diluting agent for diluting the adhesive composition into a coating solution include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as methylene chloride and ethylene chloride; , Alcohols such as propanol, butanol and 1-methoxy-2-propanol, ketones such as acetone, methyl ethyl ketone, 2-pentaton, isophorone and cyclohexane, esters such as ethyl acetate and butyl acetate, And the like can be used.

The concentration and viscosity of the coating solution thus prepared are not particularly limited and may be suitably selected according to the circumstances. For example, such that the concentration of the adhesive composition becomes 10 to 40% by mass. When a coating solution is obtained, it is not necessary to add a diluting solvent or the like, and a diluting solvent may not be added if the viscosity is such that the adhesive composition can be coated. In this case, the adhesive composition becomes a coating solution as it is.

As the method of applying the coating solution, for example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method and the like can be used.

Here, for example, in order to manufacture a liquid crystal display device composed of a liquid crystal cell and a polarizing plate, a polarizing plate is used as the base material 13 of the pressure-sensitive adhesive sheet 1A, and the release sheet 12 of the pressure- The pressure-sensitive adhesive layer 11 and the liquid crystal cell may be attached to each other.

For example, in order to manufacture a liquid crystal display device in which a phase difference plate is disposed between a liquid crystal cell and a polarizing plate, one of the release sheets 12a (or 12b) of the pressure-sensitive adhesive sheet 1B is peeled off, And the other release sheet 12b (or 12a) is peeled off, and the exposed pressure-sensitive adhesive layer 11 and the retarder are bonded to each other. Further, as the base material 13, an adhesive sheet The release sheet 12 of the pressure-sensitive adhesive layer 1A may be peeled off, and the exposed pressure-sensitive adhesive layer 11 may be bonded to the retarder.

According to the above-mentioned pressure-sensitive adhesive sheets 1A, 1B, the pressure-sensitive adhesive layer 11 has excellent stress relaxation properties. Therefore, even when the pressure-sensitive adhesive sheet 11 is applied to the adhesion of a polarizing plate, for example, 11, so that excellent light-leak property and high durability are exhibited.

The embodiments described above have been described for the purpose of facilitating understanding of the present invention and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design modifications and equivalents falling within the technical scope of the present invention.

For example, the release sheet 12 of the pressure-sensitive adhesive sheet 1A may be omitted and either of the release sheets 12a and 12b in the pressure-sensitive adhesive sheet 1B may be omitted.

[Example]

Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the scope of the present invention is not limited to these Examples and the like.

[Example 1]

1. Process (1)

A reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen inlet tube was charged with 97.0 parts by mass of n-butyl acrylate, 3.0 parts by mass of acrylic acid, 150.0 parts by mass of acetone, and 2,2'-azobisisobutylo And 0.06 part by mass of nitrile, and the air in the reaction vessel was replaced with nitrogen gas. While stirring in the nitrogen atmosphere, the reaction solution was heated to 60 占 폚, allowed to react for 6 hours, and then cooled to room temperature. Here, a part of the obtained solution was subjected to GPC measurement by the below-mentioned method to confirm the formation of the copolymer (A) having a weight average molecular weight of 1,500,000. Also, the conversion rate (the value obtained by dividing the mass of the copolymer obtained by polymerizing the monomer to the total mass of the monomer used as the raw material) was 80%.

2. Process (2)

To the solution of the copolymer (A) obtained in the above step (1), 150 parts by mass of toluene, 2.2 parts by mass of 2-hydroxyethyl acrylate, and 2,2'-azobis (2,4-dimethylvaleronitrile ) Was added, the temperature was raised to 70 占 폚, and the mixture was allowed to react for 6 hours and then cooled to room temperature. Here, a part of the obtained solution was again subjected to GPC measurement to confirm that there was almost no change in the peak top of the copolymer (A) having a weight average molecular weight of 1,500,000, and from the result of this GPC measurement, The yield of the copolymer (B) having a new weight average molecular weight of 40,000 was confirmed by measuring the results of GPC measurement. To this solution, ethyl acetate was added to obtain an acrylic polymer solution (solution of a mixture of the copolymer (A) and the copolymer (B)) having a solid content of 23.0% by mass. Here, the mixing ratio of the copolymer (A) and the copolymer (B) was a mass ratio of 80:20 since the conversion ratio in the step (1) was 80%.

3. Process (3)

100 parts by mass in terms of solid content of the acrylic polymer solution obtained in the above step (2) was aliquoted and diluted with methyl ethyl ketone to a solid content concentration of 20% by mass. Then, as a crosslinking agent (C), a trityl diisocyanate (TDI) adduct of trimethylol propane in an amount corresponding to 1 equivalent of the hydroxyl group of the copolymer (B) (trade name: Coronate L, manufactured by Nippon Polyurethane Co., did. Finally, 0.2 parts by mass of 3-glycidoxypropyltrimethoxysilane (trade name: KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent (D) was added and sufficiently stirred to obtain a diluted solution ≪ / RTI >

Table 1 shows the composition of the adhesive composition. The abbreviations used in Table 1 are as follows.

[Copolymers (A) and (B)]

BA: n-butyl acrylate

AA: Acrylic acid

HEA: 2-hydroxyethyl acrylate

HBA: 4-hydroxybutyl acrylate

HEMA: 2-hydroxyethyl methacrylate

DEM: Methacrylic acid N, N-2-dimethylaminoethyl

[Crosslinking agent (C)]

· Isocyanate-based crosslinking agent

   TDI series: trimethylene diisocyanate adduct of trimethylolpropane (trade name " Coronate L " manufactured by Nippon Polyurethane Industry Co., Ltd.)

   Isocyanurate: isocyanurate of hexamethylene diisocyanate ("Coronate HXR", trade name, manufactured by Nippon Polyurethane Industry Co., Ltd.)

· Other crosslinking agents (epoxy crosslinking agents)

     N, N, N ', N'-tetraglycidyl-m-xylylenediamine (trade name "TETRAD-X" manufactured by Mitsubishi Chemical Corporation)

[Silane coupling agent (D)]

KBM403: 3-glycidoxypropyltrimethoxysilane (trade name: KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.)

"KBE9007: 3-isocyanate propyltriethoxysilane (trade name" KBE9007 ", manufactured by Shin-Etsu Chemical Co., Ltd.)

KBE403: 3-glycidoxypropyltriethoxysilane (trade name " KBE403 ", product of Shin-Etsu Chemical Co., Ltd.)

The diluted solution of the obtained sticky composition was applied to the release treatment surface of a release sheet (SP-PET3811, thickness: 38 mu m) having one side of the polyethylene terephthalate film peeled off with a silicone release agent, And then heat-treated at 90 DEG C for 1 minute to form a pressure-sensitive adhesive layer.

Then, a polarizing plate, which is a polarizing film with a discotic liquid crystal layer and integrated with a polarizing film and a viewing angle enlarging film, was attached so that the pressure-sensitive adhesive layer and the discotic liquid crystal layer were in contact with each other and cured at 23 DEG C and 50% RH for 7 days To obtain a polarizer with a pressure-sensitive adhesive layer.

[Examples 2 to 34 and Comparative Examples 1 to 6]

Except that the reaction conditions were adjusted so that the conversion ratio of the copolymer (A) was the value shown in Table 1, and the addition amount of each monomer was changed so that the ratio of each monomer constituting the sticky composition became the value shown in Table 1 1, a pressure-sensitive adhesive sheet with a pressure-sensitive adhesive layer was produced.

[Example 35]

97 parts by mass of butyl acrylate and 3 parts by mass of acrylic acid were copolymerized by a usual polymerization method to obtain a copolymer (A) having a weight average molecular weight of 1.5 million (measured by GPC). Similarly, 90 parts by mass of butyl acrylate and 10 parts by mass of 2-hydroxyethyl acrylate were copolymerized to obtain a copolymer (B) having a weight average molecular weight of 40,000 (measured by GPC).

80 parts by mass of the obtained copolymer (A) and 20 parts by mass of the copolymer (B) were mixed and diluted with methyl ethyl ketone to a solid concentration of 20% to obtain an acrylic polymer solution. Thereafter, a diluted solution of the sticky composition was obtained in the same manner as in Example 1. Then, a polarizing plate with a pressure-sensitive adhesive layer was prepared in the same manner as in Example 1, using the diluted solution of the adhesive composition.

[Test Example 1] (Adhesive strength measurement - reworkability evaluation)

A sample of 25 mm (width) and 100 mm (length) was cut out with the polarizer with a pressure-sensitive adhesive layer obtained in the example or the comparative example and the release sheet was peeled off and exposed to a non-alkali glass (Eagle XG made by Corning) After the application, it was pressurized in an autoclave made by Kurihara Seisakusho Co., Ltd., at 0.5 MPa and 50 캜 for 20 minutes. Thereafter, the film was allowed to stand under the conditions of 23 ° C and 50% RH for 24 hours, and then the adhesive strength (Tensilon) was measured using a tensile tester (Tensilon manufactured by Orientech) under the conditions of a peeling speed of 30 mm / min and a peeling angle of 180 degrees (N / 25 mm) was measured.

Further, after being left under the conditions of 23 占 폚 and 50% RH for 14 days, the adhesive force (adhesive strength after 14 days of application; N / 25 mm) was measured in the same manner as described above. The preferable range of adhesive force is 0.1 N / 25 mm or more and less than 25 N / 25 mm.

Based on the adhesive strength after 14 days of the application, the reworkability was evaluated according to the following criteria.

The results are shown in Table 2.

Adhesion after 14 days of application: 2ON / 25mm or less: ◎

Adhesion after 14 days of application: 2ON / 25mm, less than 25N / 25mm: ○

Adhesion after 14 days of application: 25N / 25mm or more: x

[Test Example 2] (Measurement of gel fraction)

(SP-PET3801 manufactured by LINTEC CORPORATION, thickness: 38 mu m) obtained by peeling one surface of a polyethylene terephthalate film with a silicone-based releasing agent was used in place of the polarizer used in the production of the polarizing plate with a pressure- , Thereby producing a pressure-sensitive adhesive sheet. Specifically, the release sheet was laminated on the pressure-sensitive adhesive layer having a thickness of 25 占 퐉 obtained in the example or the comparative example such that the side of the release treatment surface was in contact with the pressure-sensitive adhesive layer to prepare a pressure-sensitive adhesive sheet having a release sheet / pressure- .

The obtained pressure-sensitive adhesive sheet was cured for 7 days under conditions of 23 ° C and 50% RH. Thereafter, the pressure-sensitive adhesive sheet was sampled at a size of 80 mm × 80 mm, the pressure-sensitive adhesive layer was wrapped with a polyester mesh (mesh size 200) The mass of the adhesive alone was weighed with a precision scale. The mass at this time is denoted by M1.

Using Soxhlet, a sample of the pressure-sensitive adhesive was immersed in an ethyl acetate solvent, refluxed, and treated for 16 hours. Thereafter, the pressure-sensitive adhesive was taken out and dried in air at a temperature of 23 DEG C and a relative humidity of 50% for 24 hours, and further dried in an oven at 80 DEG C for 12 hours. The mass at this time is referred to as M2. The gel fraction (%) is expressed by (M2 / M1) x100. The results are shown in Table 2.

[Test Example 3] (Measurement of optical performance)

(SP-PET3801 manufactured by LINTEC CORPORATION, thickness: 38 DEG C) in which one side of the polyethylene terephthalate film was peeled off with a silicone-based releasing agent was used in place of the polarizing plate used in the production of the polarizing plate with a pressure- , Thereby producing a pressure-sensitive adhesive sheet. Specifically, the release sheet was laminated on the pressure-sensitive adhesive layer having a thickness of 25 占 퐉 obtained in the example or the comparative example such that the side of the release treatment surface was in contact with the pressure-sensitive adhesive layer to prepare a pressure-sensitive adhesive sheet having a release sheet / pressure- .

The obtained pressure-sensitive adhesive sheet was cured for 7 days under conditions of 23 DC and 50% RH. The haze value (%) of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet was measured in accordance with JIS K 7105 using a haze meter (NDH2000, manufactured by Nippon Denshoku Chemical Co., Ltd.). The results are shown in Table 2. The haze value range is preferably 0 to 5%.

[Test Example 4] (Evaluation of durability)

The polarizing plate with a pressure-sensitive adhesive layer obtained in Example or Comparative Example was adjusted to a size of 233 mm x 309 mm using a cutting apparatus (Super Cutter, PN1-600 manufactured by Ozone Systems Co., Ltd.). The peel-off sheet was peeled off and pasted to a non-alkali glass (Eagle XG manufactured by Corning) through the exposed pressure-sensitive adhesive layer, and then pressurized at 50 MPa and 50 MPa for 20 minutes in an autoclave made by Kurihara Seisakusho.

Thereafter, the mixture was placed under the conditions of the following durability conditions, and after 500 hours, observations were made using a 10-fold magnifying glass. The appearance change was based on the following. The results are shown in Table 2.

◎: On four sides, without defect.

○: On the 4 sides, there are no defects in the area 0.6 mm or more from the outer end.

X: At least one of the four sides has a defect in appearance of an adhesive of 0.1 mm or more such as swelling, peeling, foaming, and gold at a portion of 0.6 mm or more from the outer peripheral edge.

≪ Durability condition &

· 60 ° C, relative humidity 90%

· Drying at 80 ℃

[Test Example 5] (Light leakage test)

The polarizing plate with a pressure-sensitive adhesive layer obtained in Example or Comparative Example was adjusted to a size of 233 mm 309 mm using a cutting apparatus (Super Cutter, PN1-600 manufactured by Ozone Systems Co., Ltd.). The peel-off sheet was peeled off and pasted to a non-alkali glass (Eagle XG manufactured by Corning) through the exposed pressure-sensitive adhesive layer, and then pressurized at 50 MPa and 50 MPa for 20 minutes in an autoclave made by Kurihara Seisakusho. The above bonding was performed so that the polarization axis of the polarizing plate with a pressure-sensitive adhesive layer was in the cross-Nicol state (polarizing axis: ∠45 °, ∠135 °) on the front and back of the alkali-free glass. In this state, after leaving for 500 hours under a drying condition of 80 캜, light leakage property was evaluated by the following method. The results are shown in Table 2.

≪ Evaluation of light leakage property &

Using the MCPD-2000 manufactured by Otsuka Denshi Co., Ltd., the brightness of each area shown in Fig. 3 was measured, and the brightness difference DELTA L ^*

? L ^* = [(b + c + d + e) / 4] -a

(Where a, b, C, d, and e are luminances at predetermined measurement points (one central portion of each region) of the A region, B region, C region, D region, and E region) , And light leakage property. The smaller the value of DELTA L ^* , the smaller the light leakage.

Here, the above-mentioned weight average molecular weight is a weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC) under the following conditions (GPC measurement).

<Measurement Conditions>

GPC measurement apparatus: HLC-8020 manufactured by Tosoh Corporation

· GPC column (pass in the following sequence): manufactured by Toso Co., Ltd.

    TSK guard column HXL-H

    TSK gel GMHXL (× 2)

    TSK gel G2000HXL

Measurement solvent: tetrahydrofuran

· Measuring temperature: 40 ℃

As can be clearly seen from Table 2, the polarizing plate with a pressure-sensitive adhesive layer obtained in the examples had no problem in durability and excellent light-leak resistance. Examples 1 to 30, in which the amount of acrylic acid introduced into the copolymer (A) and the amount of the cross-linking agent (C) added were adjusted, were excellent in reworkability, and the haze value was also suppressed to be low. Example 1, in which an acrylic polymer solution was obtained by series polymerization, was superior to Example 35 in which an acryl-based polymer solution was obtained in a blend system in the same blending system, and had low light leakage and low haze value.

In Comparative Example 1, since the weight average molecular weight of the first (meth) acrylic acid ester copolymer (A) is too small, durability and reworkability are poor. In Comparative Example 2, since the content of hydroxyl groups in the second (meth) acrylic acid ester copolymer (B) is too small, the gel fraction (degree of crosslinking) is low and the durability is poor. In Comparative Example 3, the weight average molecular weight of the second (meth) acrylic acid ester copolymer (B) is too small, resulting in poor durability. In Comparative Example 4, the weight average molecular weight of the second (meth) acrylic acid ester copolymer (B) was too large, resulting in poor durability and reworkability. In Comparative Example 5, since the content of the second (meth) acrylic acid ester copolymer (B) was too large, the durability was poor. In Comparative Example 6, since the content of the second (meth) acrylic acid ester copolymer (B) was too small, the gel fraction (degree of crosslinking) was low and durability was poor.

The pressure-sensitive adhesive composition and pressure-sensitive adhesive of the present invention are suitable for bonding optical members such as a polarizing plate and a retardation plate, and the pressure-sensitive adhesive sheet of the present invention is suitable as a pressure-sensitive adhesive sheet for optical members such as a polarizing plate and a retardation plate.

1A, 1B ... Adhesive sheet
11 ... The pressure-
12, 12a, 12b ... Peeling sheet
13 ... materials

Claims (15)

A first (meth) acrylic acid ester copolymer (A) having a weight average molecular weight of 700,000 to 2,500,000,
A second (meth) acrylic acid ester copolymer (B) having a weight average molecular weight of 8000 to 250,000,
And a cross-linking agent (C)
Wherein the ratio of the second (meth) acrylic acid ester copolymer (B) to 100 parts by mass of the first (meth) acrylic ester copolymer (A) is 5 to 50 parts by mass,
The second (meth) acrylic acid ester copolymer (B) contains a monomer having a functional group (b1) having high reactivity with the crosslinkable group of the crosslinking agent (C) as a constituent component, and the ratio of the monomer Is 10% by mass or more in the second (meth) acrylic acid ester copolymer (B)
The first (meth) acrylic acid ester copolymer (A) does not contain a monomer having a functional group reactive with the crosslinkable group of the crosslinking agent (C) as a constituent, and the second (meth) acrylic acid ester copolymer (A1) having a lower reactivity with the crosslinkable group of the crosslinking agent (C) than the functional group (b1) of the crosslinking agent (b1). The method according to claim 1,
Wherein the first (meth) acrylic acid ester copolymer (A) does not contain, as a constituent component, a monomer having a functional group having a high reactivity with the crosslinkable group of the crosslinking agent (C). The method according to claim 1,
The functional group (a1) in the first (meth) acrylic acid ester copolymer (A) is a carboxyl group,
The functional group (b1) in the second (meth) acrylic acid ester copolymer (B) is a hydroxyl group,
Wherein the cross-linking agent (C) is an isocyanate-based cross-linking agent. The method of claim 3,
Wherein the first (meth) acrylic acid ester copolymer (A) contains, as monomer units constituting the copolymer, from 0 to 15 mass% of a carboxyl group-containing monomer. The method of claim 3,
Wherein the second (meth) acrylic acid ester copolymer (B) contains 3 to 40 mass% of a hydroxyl group-containing monomer as a monomer unit constituting the copolymer. The method of claim 3,
The content of the isocyanate crosslinking agent is such that the isocyanate group of the isocyanate crosslinking agent is 0.1 to 5 equivalents based on the amount of the functional group (b1) in the second (meth) acrylic acid ester copolymer (B) Lt; / RTI &gt; The method according to claim 1,
And a silane coupling agent (D). 8. The method of claim 7,
Wherein the content of the silane coupling agent (D) is 0.05 to 0.5 parts by mass based on 100 parts by mass of the first (meth) acrylic acid ester copolymer (A). A method for producing the adhesive composition according to claim 1,
(1) of producing the first (meth) acrylic acid ester copolymer (A) by radical polymerization of the monomer constituting the first (meth) acrylic acid ester copolymer (A) at a conversion of 50 to 90% ,
Wherein the monomer remaining in the polymerization of the first (meth) acrylic acid ester copolymer (A) and the monomer having the functional group (b1) are subjected to radical copolymerization in the presence of the first (meth) acrylic acid ester copolymer (A) (2) of producing the second (meth) acrylic acid ester copolymer (B)
And a step (3) of adding the cross-linking agent (C). 10. The method of claim 9,
Wherein the monomer remaining in the polymerization of the first (meth) acrylic acid ester copolymer (A) and the monomer remaining in the step (2) of producing the second (meth) acrylic acid ester copolymer (B) Is subjected to radical copolymerization at a conversion of 70 to 100%. 10. The method of claim 9,
A method for producing the adhesive composition according to claim 7,
And further adding the silane coupling agent (D). A pressure-sensitive adhesive which is crosslinked with the pressure-sensitive adhesive composition according to any one of claims 1 to 8. A pressure-sensitive adhesive sheet comprising a substrate and a pressure-sensitive adhesive layer,
Wherein the pressure-sensitive adhesive layer comprises the pressure-sensitive adhesive according to claim 12. 14. The method of claim 13,
Wherein the substrate is an optical member. Two release sheets,
And a pressure-sensitive adhesive layer sandwiched between the release sheets so as to contact the release surfaces of the two release sheets,
Wherein the pressure-sensitive adhesive layer comprises the pressure-sensitive adhesive according to claim 12.

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