KR101914458B1 - Adhesive composition, adhesive and adhesive sheet - Google Patents

Abstract

A pressure-sensitive adhesive and a pressure-sensitive adhesive sheet which are excellent in stress relaxation property and can prevent light leakage when applied to an optical member such as a polarizing plate, and also have excellent durability and, furthermore, good workability.
The adhesive composition according to the present invention comprises a first (meth) acrylic acid ester polymer (A) having a weight average molecular weight of 500,000 to 3,000,000 and a second (meth) acrylic acid ester polymer (B) having a weight average molecular weight of 8,000 to 30,000, And a crosslinking agent (C), wherein the first (meth) acrylic acid ester polymer (A) contains substantially no acidic group and has a reactivity with the crosslinking agent (C) Wherein the second (meth) acrylic acid ester polymer (B) contains substantially no acidic group and also contains, as monomer units constituting the polymer, a crosslinking agent (C) containing a hydroxyl group-containing monomer (a) satisfying the formula (I) Containing monomer (b) having a reactivity with the hydroxyl group-containing monomer (b) satisfying the following formula (I).
Reactivity with crosslinking agent (C): hydroxyl group-containing monomer (a) <hydroxyl group-containing monomer (b) (I)

Description

[0001] ADHESIVE COMPOSITION, ADHESIVE AND ADHESIVE SHEET [0002]

The present invention relates to 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, a pressure-sensitive adhesive and a pressure-sensitive adhesive sheet suitable for an optical member such as a polarizing plate.

Generally, in a liquid crystal panel, a pressure-sensitive adhesive layer formed of a pressure-sensitive adhesive composition is often used to adhere a polarizing plate or a retardation plate to a glass substrate of a liquid crystal cell or the like. However, since optical members such as a polarizing plate and a retarder are easily shrunk due to heat or the like, shrinkage 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 white peeling) 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.

As a method for preventing this, there are (1) a method of suppressing the shrinkage of the optical member by bonding a pressure-sensitive adhesive layer having a high adhesive force and an excellent shape stability to an optical member such as a polarizing plate, or (2) And a method of using a pressure-sensitive adhesive layer having a small stress at the time. As the method (1), it is effective to use a pressure-sensitive adhesive layer having a high storage elastic modulus as disclosed 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 coping with deformation of the optical member.

In order to carry out the method (2), Patent Document 2 discloses a copolymer comprising (A) an alkyl (meth) acrylate and 0.5 to 20% by weight of a polymerizable monomer having a functionality for a crosslinking agent, (B) 20 to 200 parts by weight of a low molecular weight (meth) acrylic (co) polymer having a weight average molecular weight of 30,000 or less, (C) a cross-linking structure (Meth) acryl-based (co) polymer / (functional group of the high molecular weight (meth) acrylic copolymer] of 0.005 to 5 parts by weight, A pressure-sensitive adhesive for a polarizing plate in which the displayed functional group distribution ratio is in the range of 0 to 15% by weight.

Similarly, in order to carry out the method (2), Patent Document 3 discloses that 100 parts by mass of the polymer (a) in all the (meth) acrylic acid esters having a weight average molecular weight of 800,000 to 200,000, (A) having a high reactivity with the cross-linking agent (B), and a cross-linking agent (B), wherein the (meth) acrylic acid ester (A) (B) comprises a monomer unit having a functional group with lower reactivity than the crosslinking agent (B) and the functional group of the copolymer (a).

[Patent Document 1] JP-A-2006-235568 [Patent Document 2] Patent No. 3533589 [Patent Document 3] JP-A-2009-108122

The pressure-sensitive adhesives disclosed in Patent Documents 2 and 3 are intended to obtain stress relaxation property by preferentially crosslinking a (meth) acrylic copolymer having a high molecular weight. However, such a pressure-sensitive adhesive has poor durability and, for example, under moist heat conditions, peeling has occurred at the pressure-sensitive adhesive interface. In addition, stress relaxation property is not always sufficient, and light leakage sometimes occurs when applied to an optical member such as a polarizing plate. Furthermore, since the adhesive force tends to increase with the lapse of time after the application, the workability is also insufficient.

An object of the present invention is to provide a pressure-sensitive adhesive composition, a pressure-sensitive adhesive, and a pressure-sensitive adhesive which are excellent in stress relaxation property and excellent in durability when applied to an optical member such as a polarizing plate, And to provide a sheet.

(Meth) acrylic acid ester polymer (A) having a weight average molecular weight of 500,000 to 3,000,000 and a second (meth) acrylic acid ester having a weight average molecular weight of 8,000 to 30,000 1. A sticky composition comprising a polymer (B) and a crosslinking agent (C), wherein the first (meth) acrylic acid ester polymer (A) contains substantially no acidic group, Wherein the second (meth) acrylic acid ester polymer (B) contains a hydroxyl group-containing monomer (a) having reactivity with the crosslinking agent (C) satisfying the following formula (I) (B) having a hydroxyl group-containing monomer (b) having a reactivity with the crosslinking agent (C) satisfying the following formula (I) as a monomer unit constituting the crosslinking agent (Invention 1).

Reactivity with crosslinking agent (C): hydroxyl group-containing monomer (a) <hydroxyl group-containing monomer (b) (I)

The pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition according to the invention (Invention 1) exhibits an appropriate cohesive force and excellent stress relaxation property. By using the pressure-sensitive adhesive having excellent stress relaxation property, a pressure-sensitive adhesive sheet having both excellent leak light resistance and durability when applied to an optical member such as a polarizing plate and further having excellent workability can be obtained. In addition, since each polymer of the adhesive composition does not substantially contain an acidic group, corrosion of the metal can be suppressed when the adherend comprises a metal or when it contains a metal.

In the above invention (Invention 1)

(i) The number of carbon atoms bonded to the carbon atom to which a hydroxyl group is bonded in the hydroxyl group-containing monomer (b) of the second (meth) acrylic acid ester polymer (B) (A) is less than the number of carbon atoms bonded to the carbon atom to which the hydroxyl group is bonded in the hydroxyl group-containing monomer (a) (Invention 2)

(ii) the number of carbon atoms bonded to the carbon atom to which the hydroxyl group is bonded in the hydroxyl group-containing monomer (b) of the second (meth) acrylic acid ester polymer (B) Containing monomer (b) of the second (meth) acrylic acid ester polymer (B) is the same as the number of carbon atoms bonded to the carbon atom to which the hydroxyl group is bonded in the hydroxyl group-containing monomer (a) The number of carbon atoms constituting the side chain at the time of forming the polymer to be contained is preferably a number of carbon atoms constituting the side chain in the formation of the polymer contained in the hydroxyl group containing monomer (a) of the first (meth) acrylic acid ester polymer (A) (Invention 3),

(iii) the number of carbon atoms bonded to the carbon atom to which the hydroxyl group is bonded in the hydroxyl group-containing monomer (b) of the second (meth) acrylic acid ester polymer (B) Containing monomer (b) of the second (meth) acrylic acid ester polymer (B) is the same as the number of carbon atoms bonded to the carbon atom to which the hydroxyl group is bonded in the hydroxyl group-containing monomer (a) (A) contained in the first (meth) acrylic acid ester polymer (A) and the number of carbon atoms constituting the side chain during the formation of the polymer (B) of the second (meth) acrylic acid ester polymer (B) is a methacrylic acid hydroxyalkyl ester, and the number of the first (meth) acrylic acid ester Hydroxyl group-containing material of (A) monomer (a) is preferably a (invention 4), acrylic acid hydroxyalkyl ester.

In the above invention (Invention 1 to 4), the molar ratio of the hydroxyl group contained in the second (meth) acrylic acid ester polymer (B) to the hydroxyl group contained in the first (meth) acrylic acid ester polymer (A) Or more and less than 15 (invention 5).

In the above invention (Invention 1 to 5), the second (meth) acrylic acid ester polymer (B) contains 10 to 40 mass% of the hydroxyl group-containing monomer (b) as a monomer unit constituting the polymer (Invention 6).

The ratio of the second (meth) acrylic acid ester polymer (B) to 100 parts by mass of the first (meth) acrylic acid ester polymer (A) is 5 to 50 parts by mass (Invention 7).

The first (meth) acrylic acid ester polymer (A) and the second (meth) acrylic acid ester polymer (B) according to the invention (inventions 1 to 7) It is preferable that it does not substantially contain a functional group (invention 8).

In the above invention (Invention 1 to 8), it is preferable that the crosslinking agent (C) is an isocyanate crosslinking agent (Invention 9).

In the above invention (Invention 9), the content of the isocyanate-based crosslinking agent is preferably 0.1 to 3.5 equivalents based on the amount of the hydroxyl group contained in the second (meth) acrylic acid ester polymer (B) (Invention 10).

Secondly, the present invention provides a pressure-sensitive adhesive comprising the adhesive composition (Invention 1 to 10) crosslinked (Invention 11).

Thirdly, 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 11).

In the above invention (invention 12), it is preferable that the substrate is an optical member (invention 13).

Fourthly, the present invention relates to 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- The present invention provides a pressure-sensitive adhesive sheet comprising the pressure-sensitive adhesive sheet.

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 the chemical cross-linking structure of the low molecular weight polymer by preferentially crosslinking a low molecular weight polymer conventionally used as a plasticizer, It is presumed that a high molecular weight polymer is constrained by inserting a plurality of high molecular weight polymers into the three dimensional network structure to form a pseudo crosslinked structure between the high molecular weight polymers. As a result, the obtained pressure-sensitive adhesive exhibits excellent stress relaxation property with an appropriate cohesive force and can effectively prevent light leakage when applied to an optical member such as a polarizing plate, and also has excellent durability and further good workability. In addition, since each polymer of the adhesive composition according to the present invention contains substantially no acidic groups, corrosion of the metal can be suppressed when the adherend is made of a metal or when it contains a metal.

1 is a cross-sectional view of a pressure-sensitive adhesive sheet according to a first embodiment of the present invention.
2 is a sectional view of a pressure-sensitive adhesive sheet according to a second embodiment of the present invention.
3 is a drawing (color) showing evaluation criteria of a light leakage test (visual inspection) in a polarizer with a pressure-sensitive adhesive layer.

Hereinafter, an embodiment of the present invention will be described.

[Adhesive composition]

The adhesive composition according to the present embodiment comprises a first (meth) acrylic acid ester polymer (A) having a weight average molecular weight (Mw) of 500,000 to 3,000,000 and a second (meth) acrylate polymer having a weight average molecular weight (Mw) Acrylic acid ester polymer (B) and a cross-linking agent (C), and preferably further contains a silane coupling agent (D). On the other hand, in the present specification, (meth) acrylic acid ester means both of acrylic acid ester and methacrylic acid ester. Other similar terms are also the same. The term &quot; polymer &quot; also includes the concept of &quot; copolymer &quot;.

The first (meth) acrylic acid ester polymer (A) contains a hydroxyl group-containing monomer (a) which does not substantially contain an acidic group and has a reactivity with the crosslinking agent (C) acrylic ester polymer (B) substantially contains no acidic group and has a reactivity with the crosslinking agent (C) as the monomer unit constituting the polymer is represented by the following formula (I): Containing monomer (b) satisfying the following formula (1). On the other hand, the hydroxyl group-containing monomer means a monomer having a hydroxyl group in the molecule.

Reactivity with crosslinking agent (C): hydroxyl group-containing monomer (a) <hydroxyl group-containing monomer (b) (I)

That is, the reactivity of the hydroxyl group-containing monomer (b) of the polymer (B) with the crosslinking agent (C) is higher than the reactivity of the hydroxyl group-containing monomer (a) of the polymer (A) with the crosslinking agent (C).

As the acidic group, mainly carboxyl group can be mentioned, and other sulfonic acid group, phosphoric acid group and the like can be given. When the first (meth) acrylic acid ester polymer (A) and the second (meth) acrylic acid ester polymer (B) contain substantially no acidic groups and the substrate is made of a metal (for example, ITO)) or a metal (for example, when the adherend includes a metal mesh), the metal can be prevented from being corroded.

Here, &quot; substantially free of an acidic group &quot; is intended to allow the inclusion of a trace amount of the metal so as not to cause corrosion, in addition to not completely containing an acidic group. Specifically, the content of the acidic group-containing monomer as the constituent unit of the polymer (A) or (B) is usually less than 1% by mass, preferably less than 0.5% by mass, particularly preferably less than 0.1% by mass.

As described above, the second (meth) acrylic acid ester polymer (B) contains a hydroxyl group-containing monomer having high reactivity with the crosslinking agent (C) as compared with the first (meth) acrylic acid ester polymer (A) It is presumed that the second (meth) acrylic acid ester polymer (B) (low molecular weight polymer) preferentially reacts with the crosslinking agent (C) at the time of crosslinking to form a three-dimensional network structure through the crosslinking agent (C). Then, two or more molecules of the first (meth) acrylic acid ester polymer (A) (high molecular weight polymer) are inserted into the three-dimensional network structure with no direct chemical bonding or with very little chemical bonding, (The structure estimated in this way is hereinafter referred to as &quot; structure X &quot; in some cases). In this case, it is assumed that the structures A and B have a degree of freedom. It is considered that the first (meth) acrylic acid ester polymer (A) is preferably inserted into the three-dimensional network structure by including a hydroxyl group derived from the hydroxyl group-containing monomer (a) having relatively low reactivity with the crosslinking agent (C). The pressure-sensitive adhesive having such a structure X exerts an appropriate cohesive force and excellent stress relaxation property. Such a pressure-sensitive adhesive having excellent stress relaxation property, when applied to an optical member such as a polarizing plate, is excellent in light-leak resistance and also has excellent durability and can prevent lifting and peeling even under moist heat conditions. In addition, in the above structure X, uncrosslinked low-molecular-weight components for imparting stress relaxation properties are not present. Therefore, bleed-out or the like of the low-molecular-weight component which is problematic in the conventional pressure-sensitive adhesive of the stress relieving type does not occur. As a result, the pressure-sensitive adhesive obtained from the adhesive composition according to the present embodiment is also excellent in workability.

The first (meth) acrylic acid ester polymer (A) is obtained by reacting a (meth) acrylic acid alkyl ester having an alkyl group of 1 to 20 carbon atoms, a hydroxyl group-containing monomer (a) and a crosslinking agent (C) (Meth) acrylic acid ester polymer (B) is preferably a copolymer of a (meth) acrylic acid alkyl ester having an alkyl group of 1 to 20 carbon atoms and a hydroxyl group-containing monomer (b ) And a copolymer of a crosslinking agent (C) and other monomers which do not contain a functional group having reactivity, which is used by the desired method.

Examples of the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, n-pentyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl Silyl (meth) acrylate, palmityl (meth) acrylate, and stearyl (meth) acrylate. These may be used alone or in combination of two or more.

Examples of the hydroxyl group-containing monomers (a) and (b) include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) (Meth) acrylic acid hydroxyalkyl esters such as 2-hydroxybutyl, 3-hydroxybutyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate. These may be used alone or in combination of two or more.

Examples of the combination of the hydroxyl group-containing monomer (a) and the hydroxyl group-containing monomer (b) include the following (i) to (iii).

(i) the number of carbon atoms bonded to the carbon atom to which the hydroxyl group is bonded in the hydroxyl group-containing monomer (b) of the second (meth) acrylic acid ester polymer (B) Is less than the number of carbon atoms bonded to the carbon atom to which the hydroxyl group is bonded in the hydroxyl group-containing monomer (a). This is because the smaller the number of carbon atoms bonded to the carbon atom to which the hydroxyl group is bonded, the higher the nucleophilicity of the hydroxyl group and the lower the steric hindrance, so that the reactivity of the hydroxyl group is higher. Therefore, the number of carbon atoms bonded to carbon atoms to which a hydroxyl group is bonded is a priority criterion for the reactivity of the crosslinking agent (C).

For example, the case where the hydroxyl group-containing monomer (a) is a secondary hydroxyl group monomer and the hydroxyl group-containing monomer (b) is a primary hydroxyl group monomer. Specifically, it is preferable that the hydroxyl group-containing monomer (a) is 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate or 3-hydroxybutyl Is a 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate or 4-hydroxybutyl (meth) acrylate.

(meth) acrylic acid ester polymer (A) and (ii) the number of carbon atoms bonded to the carbon atom to which the hydroxyl group is bonded in the hydroxyl group-containing monomer (b) of the second (meth) acrylic acid ester polymer (B) (B) contained in the hydroxyl group-containing monomer (b) of the second (meth) acrylic acid ester polymer (B) is the same as the number of carbon atoms bonded to the carbon atom to which the hydroxyl group is bonded in the hydroxyl group- (A) in the first (meth) acrylic acid ester polymer (A) is larger than the number of carbon atoms constituting the side chain at the time of forming the polymer contained in the hydroxyl group-containing monomer (a) of the first (meth) acrylic acid ester polymer (A). When the number of carbon atoms bonded to the carbon atom to which the hydroxyl group is bonded is the same, the number of carbon atoms constituting the side chain in the monomer during formation of the polymer is far from the main chain and the steric hindrance is small, Is high.

For example, the number of the carbon atoms constituting the side chain at the time of forming the polymer of the hydroxyl group-containing monomer (a) and the hydroxyl group-containing monomer (b) Containing monomer (b) has three or four carbon atoms constituting the side chain at the time of polymer formation. On the other hand, for example, in the case of (meth) acrylic acid hydroxyalkyl ester, "the side chain is constituted at the time of polymer formation" corresponds to the part where the hydroxyalkyl moiety constitutes the side chain at the time of polymer formation. The "number of carbon atoms" means the number of carbon atoms connected from the carbon atom to which the hydroxyl group is bonded to the atom constituting the main chain at the time of polymer formation, and the number of carbon atoms in the branch chain portion in the side chain is not counted. For example, the number of the carbon atoms in the 2-hydroxypropyl acrylate is two.

(ii) is a case in which the hydroxyl group-containing monomer (a) is 2-hydroxyethyl acrylate and the hydroxyl group-containing monomer (b) is 3-hydroxypropyl (meth) Butyl.

(iii) the number of carbon atoms bonded to the carbon atom to which the hydroxyl group is bonded in the hydroxyl group-containing monomer (b) of the second (meth) acrylic acid ester polymer (B) Containing monomer (b) of the second (meth) acrylic acid ester polymer (B), the number of carbon atoms bonded to the carbon atom to which the hydroxyl group is bonded in the hydroxyl group-containing monomer (a) , The number of carbon atoms constituting the side chain at the time of polymer formation and the number of carbon atoms constituting the side chain at the time of polymer formation contained in the hydroxyl group-containing monomer (a) of the first (meth) acrylic acid ester polymer (A) , And the hydroxyl group-containing monomer (b) of the second (meth) acrylic acid ester polymer (B) is a methacrylic acid hydroxyalkyl ester, and the hydroxyl group content of the first (meth) Nomeo (a) is the case of acrylic acid hydroxyalkyl esters. When the number of carbon atoms bonded to the carbon atom to which the hydroxyl group is bonded is the same and is equal to the number of carbon atoms constituting the side chain at the time of polymer formation, it is preferable that the methacrylic acid hydroxyalkyl ester , So that the main chain becomes firmly and linearly exposed, thereby exposing the hydroxyl group to easily react with the crosslinking agent (C).

For example, it is preferable that the hydroxyl group-containing monomer (a) and the hydroxyl group-containing monomer (b) are both the primary hydroxyl group monomer or the secondary hydroxyl group monomer, and the hydroxyl group- (b) is a methacrylic acid hydroxyalkyl ester. For example, when the hydroxyl group-containing monomer (a) is 2-hydroxyethyl acrylate and the hydroxyl group-containing monomer (b) is 2-hydroxyethyl methacrylate, or when the hydroxyl group- , And the hydroxyl group-containing monomer (b) is 2-hydroxypropyl methacrylate.

Here, the molar ratio of the hydroxyl group contained in the second (meth) acrylic acid ester polymer (B) to the hydroxyl group contained in the first (meth) acrylic acid ester polymer (A) in the adhesive composition is preferably 1.0 or more and less than 15 , More preferably 2 to 10, further preferably 2 to 8.

As described above, since the amount of the hydroxyl group contained in the second (meth) acrylic acid ester polymer (B) is equal to or more than the amount of the hydroxyl group contained in the first (meth) acrylic acid ester polymer (A) (molar ratio is 1.0 or more) It is presumed that the preferential reaction of the second (meth) acrylic acid ester polymer (B) and the crosslinking agent (C) progresses more effectively when the adhesive composition according to the form is crosslinked to form the structure X well. On the other hand, when the amount of the hydroxyl group contained in the second (meth) acrylic acid ester polymer (B) is more than the amount of the hydroxyl group contained in the first (meth) acrylic acid ester polymer (A) The crosslinking of the (meth) acrylic acid ester polymer (B) becomes excessive and there is a fear that the stress relaxation property is lowered and the hydroxyl group remains even after the crosslinking, and the durability under the moist heat condition may be inferior in particular.

The second (meth) acrylic acid ester polymer (B) preferably contains 10 to 40 mass%, more preferably 10 to 30 mass%, of the hydroxyl group-containing monomer (b) as the monomer unit constituting the polymer By mass, more preferably from 10 to 20% by mass. The degree of crosslinking of the second (meth) acrylic acid ester polymer (B) is preferred by containing the hydroxyl group-containing monomer (b) within the above range, and in the combination with the first (meth) acrylic acid ester polymer (A) The stress relaxation property of the substrate can be improved more effectively. When the content of the hydroxyl group-containing monomer (b) is less than 10% by mass, the crosslinking of the second (meth) acrylic acid ester polymer (B) is insufficient and the gel fraction is low, thereby decreasing durability. On the other hand, when the content of the hydroxyl group-containing monomer (b) is more than 40% by mass, the crosslinking of the second (meth) acrylic acid ester polymer (B) becomes excessive and the stress relaxation property may deteriorate. There is a possibility that the durability under wet heat conditions is inferior. Further, when the upper limit of the content of the hydroxyl group-containing monomer (b) is set to 30% by mass, the resulting pressure-sensitive adhesive sheet is more excellent in leak resistance.

On the other hand, the content of the hydroxyl group-containing monomer in the first (meth) acrylic acid ester polymer (A) is preferably such that the content of the hydroxyl group-containing monomer in the second (meth) acrylic acid ester polymer (B) It is decided.

Examples of the other monomer include (meth) acrylate having an aliphatic ring such as cyclohexyl (meth) acrylate, (meth) acrylate having an aromatic ring such as phenyl (meth) acrylate, acrylamide, methacrylamide (Meth) acrylic acid esters having a non-cross-linkable tertiary amino group such as (meth) acrylic acid N, N-dimethylaminoethyl and N, N-dimethylaminopropyl (meth) Styrene, and the like. These may be used alone or in combination of two or more.

Among these other monomers, (meth) acrylic acid esters having a non-cross-linkable tertiary amino group such as (meth) acrylic acid N, N-dimethylaminoethyl, N, N-dimethylaminopropyl (meth) , N-dimethylaminoethyl are included as the monomer units constituting the polymer in the second (meth) acrylic acid ester polymer (B) since they have a catalytic effect of promoting the reaction between the hydroxyl group in the polymer and the crosslinking agent There may be.

In this case, the content of the (meth) acrylic acid ester having a tertiary amino group in the second (meth) acrylic acid ester polymer (B) is preferably 0.01 to 1% by mass, more preferably 0.1 to 0.5% .

Here, in order to reliably form the structure X, the first (meth) acrylic acid ester polymer (A) and the second (meth) acrylic acid ester polymer (B) may contain, in addition to the hydroxyl group, a functional group having reactivity with the cross- Is substantially not contained. Examples of such a functional group include a crosslinkable primary amino group or a secondary amino group. Examples of the monomer containing the functional group include aminoethyl (meth) acrylate, n-butylaminoethyl (meth) acrylate Containing amino group-containing monomers.

The phrase &quot; substantially free of a functional group having reactivity with the crosslinking agent (C) &quot; means that the functional group is not completely contained, and that the functional group is contained so as not to interfere with the reactivity of the hydroxyl group and the crosslinking agent will be. Specifically, in each of the polymers (A) and (B), the molar ratio of the functional group to the hydroxyl group is preferably 0.2 or less, more preferably 0.1 or less.

The polymerization forms of the first (meth) acrylic acid ester polymer (A) and the second (meth) acrylic acid ester polymer (B) may be a random copolymer or a block copolymer.

The weight average molecular weight of the first (meth) acrylic acid ester polymer (A) is from 500,000 to 3,000,000, preferably from 700,000 to 250,000, and particularly preferably from 1 million to 2,000,000. In other words, the first (meth) acrylic acid ester polymer (A) is composed of a high molecular weight polymer component. On the other hand, the weight average molecular weight in the present specification is a polystyrene reduced value measured by a gel permeation chromatography (GPC) method.

It is presumed that the structure X is satisfactorily formed because the weight average molecular weight of the first (meth) acrylic acid ester polymer (A) is within the above range and the polymer (A) has a relatively large molecular weight.

If the weight average molecular weight of the first (meth) acrylic acid ester polymer (A) is less than 500,000, there is a fear that the obtained pressure sensitive adhesive gel fraction is low and durability and reworkability are inferior. When the weight average molecular weight of the first (meth) acrylic acid ester polymer (A) is more than 300,000, the compatibility with the second (meth) acrylic acid ester polymer (B) is deteriorated and the stress relaxation property of the resultant pressure sensitive adhesive There is a concern.

On the other hand, the weight average molecular weight of the second (meth) acrylic acid ester polymer (B) is 8,000 to 30,000, preferably 10,000 to 200,000, and particularly preferably 50,000 to 100,000. In other words, the second (meth) acrylic acid ester polymer (B) is composed of a low molecular weight polymer component.

When the weight average molecular weight of the second (meth) acrylic acid ester polymer (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. In other words, when the weight average molecular weight of the second (meth) acrylic acid ester polymer (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 polymer (B) exceeds 30,000, the compatibility with the first (meth) acrylic acid ester polymer (A) The insertion of the polymer (A) into the three-dimensional network structure becomes insufficient, and as a result, the resulting pressure-sensitive adhesive may have poor durability and reworkability.

In the present embodiment, each of the first (meth) acrylic acid ester polymer (A) and the second (meth) acrylic ester polymer (B) may be used singly or in combination of two or more It is also good.

The ratio of the second (meth) acrylic acid ester polymer (B) to 100 parts by mass of the first (meth) acrylic acid ester polymer (A) is preferably from 5 to 50 parts by mass, particularly preferably from 5 to 40 parts by mass, More preferably 10 to 30 parts by mass.

The pressure sensitive adhesive obtained from the adhesive composition containing the first (meth) acrylic acid ester polymer (A) and the second (meth) acrylic acid ester polymer (B) in the above ratio is presumed to form the structure X well.

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. Of these, an isocyanate crosslinking agent having excellent reactivity with the hydroxyl groups of the polymers (A) and desirable.

The isocyanate-based crosslinking agent includes at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane di An alicyclic polyisocyanate such as isocyanate and the like and a reaction product thereof with a low molecular active hydrogen-containing compound such as a burette, isocyanurate, and further ethylene glycol, propylene glycol, neopentyl glycol, trimethylol propane, And duct bodies.

The crosslinking agent (C) may be used singly or in combination of two or more.

The content of the crosslinking agent (C) is preferably 0.05 to 5 equivalents based on the amount of the crosslinkable group (e.g. isocyanate group) of the crosslinking agent (C) based on the amount of the hydroxyl group of the second (meth) acrylic acid ester polymer (B) Preferably 0.1 to 3.5 equivalents, and particularly preferably 0.3 to 1.0 equivalents. When the amount of the crosslinkable group is less than 0.05 equivalent, the resulting adhesive agent gel fraction may be low, and sufficient cohesive strength may not be exhibited. If the amount of the crosslinkable group is 0.1 equivalents or more, particularly 0.3 equivalents or more, the resulting pressure-sensitive adhesive can be made more excellent in durability. On the other hand, if the amount of the crosslinkable group is 3.5 equivalents or less, the obtained pressure-sensitive adhesive can be made to have a good workability. In addition, it is presumed that if the amount of the crosslinkable group is 1.0 equivalent or less, the crosslinking agent (C) contributes only to the formation of the three-dimensional network structure of the polymer (B), thereby effectively preventing crosslinking of the polymer (A). As a result, the obtainable adhesive agent is excellent in stress relaxation property.

The adhesive composition according to the present embodiment preferably further contains a silane coupling agent (D). When the silane coupling agent (D) is contained, the alkoxysilyl group or the like of the silane coupling agent (D) acts on the surface of the adherend such as a glass substrate. Thus, for example, when a polarizing plate is applied to a liquid crystal glass cell, The adhesion between the liquid crystal glass cell and the liquid crystal glass cell becomes better.

As the silane coupling agent (D), an organosilicon compound having at least one alkoxysilyl group in the molecule, which has good compatibility with the pressure-sensitive adhesive component and has light transmission property, for example, substantially transparent, is suitable. The amount of the silane coupling agent (D) to be added is preferably 0.01 to 0.5 parts by mass, more preferably 0.05 to 0.3 parts by mass with respect to 100 parts by mass of the first (meth) acrylic acid ester polymer (A).

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

A variety of additives commonly used in acrylic pressure sensitive adhesives, such as antistatic agents, tackifiers, antioxidants, ultraviolet absorbers, light stabilizers, softeners, fillers, refractive index adjusters and the like can be added to the adhesive composition.

[Process for producing adhesive composition]

The adhesive composition is prepared by preparing each of the first (meth) acrylic acid ester polymer (A) and the second (meth) acrylic acid ester polymer (B) and mixing them, and at the same time, Can be prepared by adding a silane coupling agent (D) as desired.

As specific preferred examples, the (meth) acrylic acid ester polymers (A) and (B) are separately prepared by a usual radical polymerization method. The polymerization of the (meth) acrylic acid ester polymers (A) and (B) can be carried out by a solution polymerization method or the like using a polymerization initiator if desired. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, and the like.

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

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.

On the other hand, in the above-mentioned polymerization step, the weight average molecular weight of the resulting polymer can be controlled by blending a chain transfer agent such as 2-mercaptoethanol.

Next, the solutions of the obtained polymers (A) and (B) are mixed and a diluting solvent is added. Thereafter, a crosslinking agent (C) and, if desired, a silane coupling agent (D) are added and sufficiently mixed to obtain a sticky composition (coating solution) diluted with a solvent.

Examples of the diluting solvent 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-pentanone, isophorone and cyclohexanone, esters such as ethyl acetate and butyl acetate, A cellosolve solvent such as Solv may be used.

The concentration and viscosity of the coating solution thus produced are not particularly limited and may be suitably selected in accordance with the circumstances as long as they are in a coating-capable range. For example, it is diluted so that the concentration of the adhesive composition is 10 to 40% by mass. On the other hand, when a coating solution is obtained, addition of a diluting solvent or the like is not a necessary condition, and it is not necessary to add a diluting solvent 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.

〔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. On the other hand, the heat treatment may also serve as a drying treatment for volatilizing a diluting solvent or the like of the adhesive composition.

In the case of performing the heat treatment, the heating temperature is preferably 50 to 150 占 폚, particularly preferably 70 to 120 占 폚. The heating time is preferably 30 seconds to 3 minutes, and more preferably 50 seconds to 2 minutes. Furthermore, it is particularly preferable to set a curing period of about 1 to 2 weeks at room temperature (for example, 23 DEG C, 50% RH) after the heat treatment.

(Meth) acrylic acid ester polymer (B) is crosslinked by the crosslinking agent (C) by the above heat treatment (and curing), and the first (meth) acrylic acid ester polymer (A) is added to the three- It is assumed that the structure X is formed.

The pressure-sensitive adhesive according to the present embodiment preferably has an adhesive force of 0.1 to 25 N / 25 mm, particularly preferably 2 to 20 N / 25 mm, to the alkali-free glass. The adhesive force referred to herein means a 180 ° pulling off adhesive force (peeling speed 300 mm / min) according to JIS Z0237. The adhesive force is applied to an adherend with a pressure of 0.5 MPa at 50 캜 for 20 minutes, RH for 24 hours. When the adhesive force is within the above range, it is possible to prevent lifting or peeling, etc., when applied to an optical member such as a polarizing plate.

The pressure-sensitive adhesive according to the present embodiment preferably has an adhesive strength (adhesion after 14 days of application) of 0.1 to 25 N / 25 mm after 14 days of standing under the conditions of 23 ° C and 50% RH from the adherend to the adherend, Particularly preferably 2 to 20 N / 25 mm. As described above, the pressure-sensitive adhesive according to the present embodiment can be evaluated as having excellent reheat workability by suppressing an increase in adhesive strength with time.

The pressure-sensitive adhesive described above can be preferably used for an optical member. For example, the pressure-sensitive adhesive described above can be used preferably for optical members such as adhesion between optical members such as a polarizing plate (polarizing film) and a retardation film (retardation film), a polarizing plate Film) and a glass substrate. The pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive according to the present embodiment has excellent stress relaxation property. Therefore, even when the dimensional change of the adherend is large, the stress that may be caused by the dimensional change is absorbed and relaxed by the pressure- Therefore, it is possible not to peel off the adherend for a long period of time, but also to effectively prevent light leakage when used in such an optical member. In other words, the pressure-sensitive adhesive according to the present embodiment achieves compatibility between light leakage and durability. Furthermore, the pressure-sensitive adhesive according to the present embodiment has good reworkability and is free from acid, and therefore, has excellent corrosion resistance in the case where the adherend is made of a metal or contains a metal.

[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 is provided so as to contact two release sheets 12a and 12b and the release faces of the two release sheets 12a and 12b And a pressure-sensitive adhesive layer 11 sandwiched between the two release sheets 12a and 12b. On the other hand, the release surface of the release sheet in the present specification means a surface having release properties in the release sheet, and includes both the surface subjected to the release treatment and the surface exhibiting the release property without performing the release treatment.

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

The thickness of the pressure-sensitive adhesive layer 11 is appropriately determined depending on the purpose of use of the pressure-sensitive adhesive sheets 1A and 1B, but is usually in the range of 5 to 100 m, preferably 10 to 60 m. For example, When it is used as a pressure-sensitive adhesive layer, it is preferably 10 to 50 m, especially 10 to 30 m.

The base material (13) is not particularly limited, and any material used as a base sheet of a conventional adhesive sheet can be used. For example, woven or nonwoven fabric using fibers of rayon, acrylic, polyester or the like other than the desired optical member; Papers such as coated paper, glossy paper, impregnated paper, and coated paper; Metal foil such as aluminum and copper; Foams such as urethane foams and polyethylene foams; A polyethylene film, a polyethylene film, a polypropylene film, a cellulose film such as triacetylcellulose, a polyvinyl chloride film, a polyvinylidene chloride film, a polyvinylidene chloride film, a polyvinylidene chloride film, a polyethylene terephthalate film, A plastic film such as a vinyl alcohol film, an ethylene-vinyl acetate 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. The plastic film may be one-axis extended or two-axis extended.

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, a contrast enhancing film and a liquid crystal polymer 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 (the pressure-sensitive adhesive layer 11) of the present embodiment from the viewpoint of resistance to light leakage.

The thickness of the base material 13 varies depending on the type thereof. For example, in the case of an optical member, it is usually 10 m to 500 m, preferably 50 m to 300 m.

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 (Meth) acrylate copolymer film, an ethylene / (meth) acrylic acid ester copolymer film, a polystyrene film, a polyethylene naphthalate film, a polybutylene terephthalate film, a polyurethane film, an ethylene vinyl acetate film, an ionomer resin film, , A polycarbonate film, a polyimide film, a fluororesin film, or the like can be used. Such a crosslinked film may also be used. Furthermore, such a laminated film may be used.

The peeling surface of the release sheet (particularly, the surface in contact with the pressure-sensitive adhesive layer 11) is preferably peeled. 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 mu m.

In order to produce the pressure-sensitive adhesive sheet 1A, a solution (coating solution) containing the pressure-sensitive adhesive composition is coated on the release surface of the release sheet 12, heat treatment is performed to form the pressure-sensitive adhesive layer 11, And the base material 13 is laminated on the pressure-sensitive adhesive layer 11. Then, it is preferable to set the curing period.

The conditions of the heat treatment and curing 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 heat treatment is performed to form a pressure- , The peeling surface of the other release sheet 12b (or 12a) is superimposed on the pressure-sensitive adhesive layer 11.

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

For example, a polarizing plate is used as the base material 13 of the pressure-sensitive adhesive sheet 1A, and a release sheet 12 of the pressure-sensitive adhesive sheet 1A is used for manufacturing a liquid crystal display device composed of a liquid crystal cell and a polarizing plate, And the exposed pressure-sensitive adhesive layer 11 and the liquid crystal cell are laminated together.

For example, to manufacture a liquid crystal display device in which a retarder 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 , And the exposed pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1B and the retarder are bonded. Next, the release sheet 12 of the pressure-sensitive adhesive sheet 1A using the polarizing plate as the base material 13 is peeled off, and the exposed pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1A is bonded to the retarder. Further, the other release sheet 12b (or 12a) is peeled from the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet B, and the exposed pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet B is bonded to the liquid- .

According to the above-mentioned pressure-sensitive adhesive sheets 1A and 1B, the pressure-sensitive adhesive layer 11 has excellent stress relaxation properties. Therefore, even when the pressure-sensitive adhesive layer 11 is applied to the adhesion of a polarizer, for example, It can be absorbed and relaxed by the light emitting layer 11, whereby it is estimated that excellent light resistance leakage resistance and high durability are exhibited.

The embodiments described above are 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 one of the release sheets 12a and 12b in the pressure-sensitive adhesive sheet 1B may be omitted.

[Examples]

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. Preparation of Polymer (A)

To a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube were added 99.0 parts by mass of n-butyl acrylate, 1.0 part by mass of 2-hydroxyethyl acrylate, 200 parts by mass of ethyl acetate, And 0.08 part by mass of bisisobutyronitrile were placed, 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 16 hours, and then cooled to room temperature. Here, a part of the obtained solution was subjected to measurement of the molecular weight by the method described later, and generation of the polymer (A) having a weight average molecular weight of 157,000 was confirmed.

2. Preparation of Polymer (B)

A reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen inlet tube was charged with 81.4 parts by mass of n-butyl acrylate, 18.6 parts by mass of 4-hydroxybutyl acrylate, 200 parts by mass of ethyl acetate, 0.16 parts by mass of bisisobutylonitrile and 0.3 parts by mass of 2-mercaptoethanol were placed, and the air in the reaction vessel was replaced with nitrogen gas. While stirring in this nitrogen atmosphere, the reaction solution was heated to 70 占 폚, allowed to react for 6 hours, and then cooled to room temperature. Here, a part of the resulting solution was subjected to measurement of the molecular weight by the method described later, and the formation of the polymer (B) having a weight average molecular weight of 60,000 was confirmed.

3. Preparation of adhesive composition

After mixing 100 parts by mass (solid content conversion value) of the polymer (A) obtained in the above step (1) and 20 parts by mass (solid content conversion value) of the polymer (B) obtained in the above step (2) , 3.0 parts by mass of a trade name "Takenate D-110N" manufactured by Mitsui Chemicals, Inc., a xylene diisocyanate adduct of trimethylol propane in an amount corresponding to 0.6 equivalent of the hydroxyl group of the polymer (B)) was added. Finally, 0.3 part by mass of 3-glycidoxypropyltrimethoxysilane (trade name: KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.) was added as the silane coupling agent (D) and sufficiently stirred to obtain a diluted solution of the adhesive composition.

The amount of hydroxyl groups (H [OH]) in the polymer (A) was 8.62 mmol and the amount of hydroxyl groups in the polymer (B) (L [OH]) was calculated to be 25.84 mmol from the ratio of the blended monomers do. Therefore, the ratio (L [OH] / H [OH]) of the number of moles of hydroxyl groups in 20 parts by mass of the polymer (B) to the number of moles of hydroxyl groups in 100 parts by mass of the polymer (A) is 3.00.

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

[Polymers (A) and (B)]

BA: n-butyl acrylate

AA: Acrylic acid

DM: methacrylic acid N, N-dimethylaminoethyl

HEA: 2-hydroxyethyl acrylate

HEMA: 2-hydroxyethyl methacrylate

2HPA: 2-hydroxypropyl acrylate

4HBA: 2-hydroxybutyl acrylate

H [OH] (mmol): the number of moles of hydroxyl groups calculated as the amount (parts by mass) of polymer (A) added as (g)

L [OH] (mmol): the amount of polymer (B) added (parts by mass), expressed as (g)

[Isocyanate crosslinking agent (C)]

XDI-TMP: xylene diisocyanate adduct of trimethylol propane (trade name "Takenate D-110N" manufactured by Mitsui Chemicals, Inc., polyurethane)

[Silane coupling agent (D)]

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

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

Then, a polarizing plate made of a polarizing film with a discotic liquid crystal layer and having a polarizing film and a viewing angle enlarging film integrated was laminated so that the exposed surface of the pressure sensitive adhesive layer and the surface of the discotic liquid crystal layer were in contact with each other. For 7 days to obtain a polarizing plate with a pressure-sensitive adhesive layer.

[Examples 2 to 11 and Comparative Examples 1 to 3]

(A) and the polymer (B) were changed as shown in Table 1, in the same manner as in Example 1, except that the kind and ratio of each monomer constituting the adhesive composition, the kind and amount of the crosslinking agent and the silane coupling agent and the blending ratio of the polymer To prepare a polarizing plate with a pressure-sensitive adhesive layer.

Here, the weight average molecular weight (Mw) described above 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 measuring apparatus: HLC-8020 manufactured by Tosoh Corporation

· GPC column (pass in the following order): TOSOH Corporation

  TSK guard column HXL-H

  TSK gel GMHXL (× 2)

  TSK gel G2000 HXL

Measurement solvent: tetrahydrofuran

· Measuring temperature: 40 ℃

[Test Example 1] (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 x 309 mm by using a cutting device (super cutter, manufactured by Oginosei Co., Ltd., PN1-600). The peeled sheet was peeled off and attached to a non-alkali glass (Eagle XG, made by Corning) through the exposed pressure-sensitive adhesive layer, followed by pressurization at 0.5 MPa and 50 deg. C for 20 minutes in an autoclave made by Kurihara Seisakusho. On the other hand, the above bonding was carried out so that the polarization axis of the polarizing plate with a pressure-sensitive adhesive layer was in the cross-Nicol state (polarizing axis: angle 45 deg., Angle 135 deg.) On the front and back of the alkali-free glass. In this state, the sample was allowed to stand in an 80 ° C. dry environment for 250 hours, and then left for 2 hours in an environment of 23 ° C. and 50% RH. Using this sample as a sample, the light leakage property was evaluated by the following method. The results are shown in Table 2.

 <Evaluation of Light Leakage Property: Visual>

The sample was placed on a flat illuminator (manufactured by DENSO SANGEN CO., LTD., HF-SL-A312LC, illuminance: 26,000 Lux, luminance: 10,000 cd) and photographed with a two-dimensional color intensity meter (CA- And converted into luminance distribution images by analysis software (CA-S20w, manufactured by Konica Minolta). The luminance distribution image of the obtained sample was evaluated based on the evaluation criteria shown in Fig.

[Test Example 2] (Durability Evaluation)

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 by using a cutting device (super cutter, manufactured by Oginosei Co., Ltd., PN1-600). The peeling sheet was peeled off and attached to an alkali-free glass (Eagle XG, manufactured by Corning) through the exposed pressure-sensitive adhesive layer, followed by pressurization at 0.5 MPa and 50 캜 for 20 minutes in an autoclave made by Kurihara Seisakusho.

Thereafter, they were placed under the conditions of the following durability conditions, and observation was carried out using a 10-fold magnifier after 500 hours. The appearance change was based on the following. The results are shown in Table 2.

◎: On four sides, without defect

○: On four sides, there are no defects in the area of 0.6 mm or more from the peripheral edge

X: At least one side of four sides, at least 0.6 mm from the outer peripheral end, has appearance defects such as peeling, peeling, foaming, streaking or the like of a pressure-sensitive adhesive of 0.1 mm or more

&Lt; Durability condition &

· 60 degrees, relative humidity 90% RH

[Test Example 3] (Evaluation of reworkability)

The polarizer with a pressure-sensitive adhesive layer obtained in Examples and Comparative Examples was cut to produce samples each having a width of 25 mm and a length of 100 mm. The release sheet was peeled off from the sample, and the sample was stuck to an alkali-free glass (Eagle XG, made by Corning) through the exposed pressure-sensitive adhesive layer. Then, the sample was transferred to an autoclave of Kurihara Seisakusho Co., Lt; / RTI &gt; Then, the sample was allowed to stand under the condition of 50 캜 dry for 48 hours and conditioned (conditioned) for 3 hours under conditions of 23 캜 and 50% RH. Thereafter, the sample was peeled off from the alkali-free glass by hand, and the dirt on the surface of the alkali-free glass was visually evaluated. Evaluation was carried out on the basis of the following. The results are shown in Table 2.

○: Dirt of the glass · No residual adhesive

△: Dirt of the glass · The adhesive remained a little

X: Dirt of the glass · Remarkability of the adhesive remained remarkable

[Test Example 4] (Evaluation of corrosion resistance)

The release sheet of the polarizing plate with a pressure-sensitive adhesive layer obtained in Example or Comparative Example was peeled off and attached to a copper foil (thickness: 80 탆), and then kept for 500 hours in an atmosphere of 60 캜 and 90% RH. Thereafter, the polarizing plate with a pressure-sensitive adhesive layer was peeled off from the copper foil, and the surface of the exposed copper foil was observed with naked eyes to confirm whether or not there was corrosion. The results are shown in Table 2.

○: No corrosion

X: Corrosive

[Test Example 5] (Evaluation of haze value)

(Constituting member before the polarizer attachment) composed of the release sheet / pressure-sensitive adhesive layer (thickness: 25 m) obtained in the manufacturing process of the example or the comparative example was prepared. The surface of the pressure-sensitive adhesive layer on which the construct was exposed was pasted with soda-lime glass (haze value: 0%), and the release sheet was peeled off to produce a measurement sample.

The haze value (%) (sometimes omitted in Hz (%)) of the measurement sample was measured using a haze meter (NDH2000 manufactured by Nippon Denshoku Kogyo Co., Ltd.) according to JIS K7105. On the other hand, the range of the haze value is preferably 0 to 3%, and those within the above range are evaluated as &amp; cir &amp; The results are shown in Table 2.

As can be seen from Table 2, the polarizer with a pressure-sensitive adhesive layer obtained in the examples had both excellent light-leak resistance and durability, and was excellent in reworkability, corrosion resistance and optical characteristics.

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 (14)

A first (meth) acrylic acid ester polymer (A) having a weight average molecular weight of 500,000 to 3,000,000,
A second (meth) acrylic acid ester polymer (B) having a weight average molecular weight of 8000 to 300000,
A pressure-sensitive adhesive composition containing a cross-linking agent (C)
The first (meth) acrylic acid ester polymer (A) is a monomer unit constituting the polymer, and contains a hydroxyl group-containing monomer (a) having a reactivity with the crosslinking agent (C) satisfying the following formula (I) , The content of the acidic group-containing monomer is less than 1% by mass,
Wherein the second (meth) acrylic acid ester polymer (B) is a monomer unit constituting the polymer, and the second (meth) acrylic acid ester polymer (B) is a monomer unit having a reactivity with the crosslinking agent (C) %, And the content of the acid group-containing monomer is less than 1% by mass.
Reactivity with crosslinking agent (C): hydroxyl group-containing monomer (a) <hydroxyl group-containing monomer (b) (I) The method according to claim 1,
The number of carbon atoms bonded to the carbon atom to which the hydroxyl group is bonded in the hydroxyl group-containing monomer (b) of the second (meth) acrylic acid ester polymer (B) Is less than the number of carbon atoms bonded to the carbon atom to which the hydroxyl group in the hydroxyl group-containing monomer (a) is bonded. The method according to claim 1,
The number of the carbon atoms bonded to the carbon atom to which the hydroxyl group is bonded in the hydroxyl group-containing monomer (b) of the second (meth) acrylic acid ester polymer (B) The number of carbon atoms bonded to the carbon atom to which the hydroxyl group is bonded in the hydroxyl group-containing monomer (a) is the same, and
The number of carbon atoms constituting the side chain in the formation of the polymer contained in the hydroxyl group-containing monomer (b) of the second (meth) acrylic acid ester polymer (B) Contained in the monomer (a) is larger than the number of carbon atoms constituting the side chain at the time of polymer formation. The method according to claim 1,
The number of the carbon atoms bonded to the carbon atom to which the hydroxyl group is bonded in the hydroxyl group-containing monomer (b) of the second (meth) acrylic acid ester polymer (B) The number of carbon atoms bonded to the carbon atom to which the hydroxyl group is bonded in the hydroxyl group-containing monomer (a) is the same as the number of carbon atoms bonded to the hydroxyl group-containing monomer (b) in the second (meth) acrylic acid ester polymer , The number of carbon atoms constituting the side chain at the time of polymer formation and the number of carbon atoms constituting the side chain at the time of polymer formation contained in the hydroxyl group-containing monomer (a) of the first (meth) acrylic acid ester polymer (A) And
The hydroxyl group-containing monomer (b) of the second (meth) acrylic acid ester polymer (B) is a methacrylic acid hydroxyalkyl ester, and the hydroxyl group-containing monomer (a) of the first (meth) , And acrylic acid hydroxyalkyl ester. The method according to claim 1,
Wherein the molar ratio of the hydroxyl group contained in the second (meth) acrylic acid ester polymer (B) to the hydroxyl group contained in the first (meth) acrylic acid ester polymer (A) is 1.0 or more and less than 15. delete The method according to claim 1,
Wherein the ratio of the second (meth) acrylic acid ester polymer (B) to 100 parts by mass of the first (meth) acrylic acid ester polymer (A) is 5 to 50 parts by mass. The method according to claim 1,
The first (meth) acrylic acid ester polymer (A) and the second (meth) acrylic acid ester polymer (B) may have a molar ratio of the functional group having reactivity with the crosslinking agent (C) By weight. The method according to claim 1,
Wherein the cross-linking agent (C) is an isocyanate-based cross-linking agent. The method of claim 9,
The content of the isocyanate crosslinking agent is such that the isocyanate group of the isocyanate crosslinking agent is 0.1 to 3.5 equivalents based on the amount of the hydroxyl group contained in the second (meth) acrylic acid ester polymer (B). A pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition according to any one of claims 1 to 5 and 7 to 10. A pressure-sensitive adhesive sheet comprising a substrate and a pressure-sensitive adhesive layer,
The pressure-sensitive adhesive sheet according to claim 11, wherein the pressure-sensitive adhesive layer comprises the pressure-sensitive adhesive according to claim 11. The method of claim 12,
Wherein the substrate is an optical member. Two release sheets,
And a pressure-sensitive adhesive layer sandwiched between the release sheets so as to come into contact with the release surfaces of the two release sheets,
The pressure-sensitive adhesive sheet according to claim 11, wherein the pressure-sensitive adhesive layer comprises the pressure-sensitive adhesive according to claim 11.

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