WO2017098870A1

WO2017098870A1 - Adhesive composition, method for producing same, adhesive sheet, polarizing plate with adhesive layer, and laminate

Info

Publication number: WO2017098870A1
Application number: PCT/JP2016/083901
Authority: WO
Inventors: 翔黒澤; 政一清水
Original assignee: 綜研化学株式会社
Priority date: 2015-12-10
Filing date: 2016-11-16
Publication date: 2017-06-15
Also published as: TW201732007A

Abstract

[Problem] To provide an adhesive composition which is capable of forming an adhesive layer that exhibits excellent durability under high temperature high humidity conditions. [Solution] An adhesive composition which contains (A) a (meth)acrylic polymer having a glass transition temperature (Tg) of less than 0°C and (B) a (meth)acrylic oligomer having a hydrolyzable silyl group, a weight average molecular weight (Mw) of 500-30,000 and a Tg of 0°C or more.

Description

Adhesive composition and method for producing the same, adhesive sheet, polarizing plate with adhesive layer and laminate

The present invention relates to an adhesive composition and a method for producing the same, an adhesive sheet, a polarizing plate with an adhesive layer, and a laminate.

In recent years, the use of liquid crystal elements for mounting on vehicles, outdoor instruments or PC displays, televisions, etc. has expanded, and the use environment has become very severe. The liquid crystal element has a structure in which a liquid crystal material is sandwiched between two substrates (eg, a glass plate), and a polarizing plate is attached to the surface of the substrate via an adhesive layer. Therefore, the pressure-sensitive adhesive layer constituting the liquid crystal element is required to have durability under high temperature and high humidity conditions so that it can withstand a severe use environment.

In order to improve the durability of the pressure-sensitive adhesive layer under high-temperature and high-humidity conditions, generally, a technique of adding a silane coupling agent to the pressure-sensitive adhesive composition is known. Further, by increasing the surface strength of the pressure-sensitive adhesive layer, it becomes possible to prevent the pressure-sensitive adhesive layer from being heated and peeled after being placed under a high temperature and high humidity condition. In order to increase the surface strength of the pressure-sensitive adhesive layer, for example, a technique is known in which an acrylic oligomer (acrylic tackifier) having a high glass transition temperature (Tg) is unevenly distributed on the surface of the pressure-sensitive adhesive layer (for example, Patent Document 1).

However, when a silane coupling agent and an acrylic tackifier are added to the pressure-sensitive adhesive composition for the purpose of further improving durability under high temperature and high humidity conditions, the acrylic tackifier is The effect of the agent was hindered, and in particular, when a glass plate was used as an adherend, there was a problem that sufficient wet heat durability could not be imparted to the pressure-sensitive adhesive layer.

Patent Document 2 discloses an optical pressure-sensitive adhesive composition containing an acrylic polymer and an adhesion modifier composed of a specific polymer having a hydrolyzable silyl group. However, the polymers disclosed in the examples of Patent Document 2 have a weight average molecular weight of 55,000 to 97,000, which is problematic in compatibility with acrylic polymers.

JP 2014-88549 A JP 2014-37502 A

An object of the present invention is to provide a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer excellent in durability under high temperature and high humidity conditions, a method for producing the same, a pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer, and a pressure-sensitive adhesive It is providing the polarizing plate with a layer, and a laminated body.

The present inventors diligently studied to solve the above problems. As a result, the inventors found that the above problems can be solved by a pressure-sensitive adhesive composition containing a specific (meth) acrylic polymer and a specific (meth) acrylic oligomer, and completed the present invention.

The present invention includes, for example, the following [1] to [9].
[1] A (meth) acrylic polymer (A) having a glass transition temperature (Tg) of less than 0 ° C., a hydrolyzable silyl group, and a weight average molecular weight (Mw) of 500 to 30,000, And the adhesive composition containing (meth) acrylic-type oligomer (B) whose Tg is 0 degreeC or more.

[2] The pressure-sensitive adhesive composition according to [1], wherein the Mw of the (meth) acrylic oligomer (B) is 1,000 to 20,000.

[3] The pressure-sensitive adhesive composition according to [1] or [2], wherein the (meth) acrylic oligomer (B) has a hydrolyzable silyl group at the end of the molecule.

[4] The pressure-sensitive adhesive composition according to [1] or [2], wherein the (meth) acrylic oligomer (B) is an oligomer of a monomer component containing a hydrolyzable silyl group-containing monomer.

[5] The monomer component is polymerized in the presence of a hydrolyzable silyl group-containing chain transfer agent, the weight average molecular weight (Mw) is 500 to 30,000, and the glass transition temperature (Tg) is 0 ° C. or higher. A pressure-sensitive adhesive composition comprising a step of producing a (meth) acrylic oligomer (B), the (meth) acrylic polymer (A) having a Tg of less than 0 ° C., and the (meth) acrylic oligomer (B) Manufacturing method.

[6] A monomer component containing a hydrolyzable silyl group-containing monomer is polymerized, and a (meth) acryl having a weight average molecular weight (Mw) of 500 to 30,000 and a glass transition temperature (Tg) of 0 ° C. or higher. The manufacturing method of the adhesive composition containing the process which manufactures a type | system | group oligomer (B), Tg is less than 0 degreeC, and contains the (meth) acrylic-type polymer (A) and (meth) acrylic-type oligomer (B) .

[7] A pressure-sensitive adhesive sheet for polarizing plate having a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to any one of [1] to [4].

[8] A polarizing plate with a pressure-sensitive adhesive layer comprising a polarizing plate and a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to any one of [1] to [4] on at least one surface of the polarizing plate. .

[9] A laminate in which a polarizing plate, an adhesive layer formed from the adhesive composition according to any one of [1] to [4], and a glass substrate are laminated in this order.

ADVANTAGE OF THE INVENTION According to this invention, the adhesive composition which can form the adhesive layer excellent in durability under high temperature and high-humidity conditions, its manufacturing method, the adhesive sheet which has the said adhesive layer, and an adhesive A polarizing plate with a layer and a laminate can be provided.

Hereinafter, the pressure-sensitive adhesive composition and the production method thereof, the pressure-sensitive adhesive sheet, the pressure-sensitive adhesive layer-attached polarizing plate and the laminate will be described.
In the present specification, “polymer” is used to include homopolymers and copolymers, and “polymerization” is used to include homopolymerization and copolymerization.
In addition, acrylic and methacryl are collectively referred to as “(meth) acryl”, and acrylate and methacrylate are collectively referred to as “(meth) acrylate”.

[Adhesive composition]
The pressure-sensitive adhesive composition of the present invention contains a (meth) acrylic polymer (A) and a (meth) acrylic oligomer (B) described below. The pressure-sensitive adhesive composition preferably further contains a crosslinking agent (C), and may contain an additive (D) as necessary.

[(Meth) acrylic polymer (A)]
The (meth) acrylic polymer (A) has a glass transition temperature (Tg) of less than 0 ° C.

Tg of the (meth) acrylic polymer (A) can be measured with a differential scanning calorimeter, for example, by the method described in the examples. The Tg of the (meth) acrylic polymer (A) is less than 0 ° C., preferably −80 to −10 ° C., more preferably −60 to −30 ° C. It is preferable from the viewpoint of the adhesiveness of the adhesive layer to the adherend that Tg is within the above range. Moreover, it is excellent from the viewpoint of being excellent in the cohesive force of an adhesive layer as Tg is more than the said lower limit, and durability improvement.

The (meth) acrylic polymer (A) has a weight average molecular weight (Mw) measured by gel permeation chromatography method (GPC method) in terms of polystyrene, preferably 150,000 to 2.5 million, more preferably 20 It is 10,000 to 2,000,000, more preferably 250,000 to 1,500,000. When Mw is within the above range, a sufficient cohesive force is imparted to the pressure-sensitive adhesive composition, which is preferable from the viewpoint of improving durability under high temperature conditions and high temperature and high humidity conditions. Further, in the present invention, the addition of the (meth) acrylic oligomer (B) can improve the interfacial adhesive force, so that the polymer has a lower molecular weight than the polymer used in the general pressure-sensitive adhesive composition for polarizing plates. Even when is used, excellent durability can be exhibited.

The (meth) acrylic polymer (A) has an Mw / Mn measured by the GPC method of preferably 12.0 or less, more preferably 9.0 or less, and even more preferably 6.0 or less. It is preferable from the viewpoint of improving durability that Mw / Mn is within the above range.

The monomer component forming the (meth) acrylic polymer (A) is selected from (meth) acrylic acid alkyl esters, (meth) acrylic acid alkoxyalkyl esters and alkoxypolyalkylene glycol mono (meth) acrylates described below. Examples include at least one monomer (a1), a crosslinkable group-containing monomer (a2), and other monomers (a3). Hereinafter, these are also simply referred to as “monomers (a1) to (a3)”.

<< (Meth) acrylic acid alkyl ester, (meth) acrylic acid alkoxyalkyl ester and alkoxypolyalkylene glycol mono (meth) acrylate selected from at least one monomer (a1) >>

The monomer (a1) is represented by, for example, the formula (a-1).
CH ₂ = CR ¹ -COOR ² (a-1)
R ¹ is a hydrogen atom or a methyl group, and R ² is a group represented by the formula (g-1).
-(R ³ O) _n R ⁴ (g-1)
R ³ is an alkylene group, R ⁴ is an alkyl group, and n is an integer of 0 or more. The alkylene group preferably has 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms. The number of carbon atoms of the alkyl group is preferably 1 to 24, more preferably 1 to 10. n is preferably 0 to 20, more preferably 0 to 4, and still more preferably 0 to 2.

Examples of (meth) acrylic acid alkyl esters include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, and isobutyl (meth). Acrylate, tert-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, n-heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, Isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, lauryl (meth) Acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate.

Examples of (meth) acrylic acid alkoxyalkyl esters include methoxymethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, and 3-ethoxy. Examples thereof include propyl (meth) acrylate, 4-methoxybutyl (meth) acrylate, and 4-ethoxybutyl (meth) acrylate.

Examples of the alkoxypolyalkylene glycol mono (meth) acrylate include methoxydiethylene glycol mono (meth) acrylate, methoxydipropylene glycol mono (meth) acrylate, ethoxytriethylene glycol mono (meth) acrylate, ethoxydiethylene glycol mono (meth) acrylate, And methoxytriethylene glycol mono (meth) acrylate.

A monomer (a1) may be used individually by 1 type, and may use 2 or more types.
In 100% by mass of the monomer component used for forming the (meth) acrylic polymer (A), the content of the monomer (a1) is preferably 50% by mass or more, more preferably 65% by mass or more, and still more preferably. 70 to 99% by mass. When the content of the monomer (a1) is 50% by mass or more, the pressure-sensitive adhesive layer obtained is excellent in adhesive strength and cohesive strength, which is preferable.

<< Crosslinkable group-containing monomer (a2) >>
The monomer (a2) is a monomer having at least one crosslinkable group. Examples of the crosslinkable group include a hydroxyl group and a carboxyl group. Introducing a crosslinking point that can be crosslinked by the crosslinking agent (C) into the (meth) acrylic polymer (A) by using the monomer (a2) as a monomer component constituting the (meth) acrylic polymer (A). Can do.

Examples of the monomer (a2) include a carboxyl group-containing (meth) acrylate, an ethylenically unsaturated carboxylic acid, and a hydroxyl group-containing (meth) acrylic monomer.

Examples of the carboxyl group-containing (meth) acrylate include β-carboxyethyl (meth) acrylate, 5-carboxypentyl (meth) acrylate, mono (meth) acryloyloxyethyl ester succinate, ω-carboxypolycaprolactone mono ( And (meth) acrylate.

Examples of the ethylenically unsaturated carboxylic acid include (meth) acrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, and citraconic acid.

Examples of the hydroxyl group-containing (meth) acrylic monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, And hydroxyl group-containing (meth) acrylates such as 8-hydroxyoctyl (meth) acrylate.

A monomer (a2) may be used individually by 1 type, and may use 2 or more types.
In 100% by mass of the monomer component used to form the (meth) acrylic polymer (A), the content of the monomer (a2) is from the viewpoint of forming an appropriate crosslinked structure with the crosslinking agent (C) described later. The content is preferably 0.1 to 15% by mass, more preferably 0.3 to 10% by mass, and still more preferably 0.5 to 8% by mass.

<< Other monomers (a3) >>
The monomer (a3) is a monomer other than the monomers (a1) and (a2).
Examples of the monomer (a3) include (meth) acrylic monomers and vinyl group-containing monomers.

Examples of the (meth) acrylic monomer include alicyclic group-containing (meth) acrylic acid esters such as (meth) acrylic acid cycloalkyl esters, (meth) acrylic acid aryl esters, (meth) acrylic acid aralkyl esters, ( Amino group-containing (meth) acrylic ester such as (meth) acrylic acid aryloxyalkyl ester, (meth) acrylic acid aminoalkyl ester, glycidyl group-containing (meth) acrylic monomer, isocyanate group-containing (meth) acrylic monomer, amide Examples thereof include group-containing (meth) acrylic monomers and cyano group-containing (meth) acrylic monomers.

Examples of alicyclic group-containing (meth) acrylic acid esters, (meth) acrylic acid aryl esters, and (meth) acrylic acid aralkyl esters include cyclohexyl (meth) acrylate, 4-tert-butylcyclohexyl (meth) acrylate, and isobornyl. (Meth) acrylate, phenyl (meth) acrylate, and benzyl (meth) acrylate may be mentioned.

Examples of (meth) acrylic acid aryloxyalkyl esters include phenoxymethyl (meth) acrylate, 2-phenoxyethyl (meth) acrylate, 2-tolyloxyethyl (meth) acrylate, xylyloxymethyl (meth) acrylate, and naphthyl. An oxymethyl (meth) acrylate is mentioned.

Examples of the amino group-containing (meth) acrylic acid ester include dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate.

Examples of the glycidyl group-containing (meth) acrylic monomer and the isocyanate group-containing (meth) acrylic monomer include glycidyl (meth) acrylate and 2-isocyanatoethyl (meth) acrylate.

Examples of amide group-containing (meth) acrylic monomers include (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, and N-hexyl (meth) acrylamide. Is mentioned.
Examples of the cyano group-containing (meth) acrylic monomer include alkyl cyanoacrylate and (meth) acrylonitrile.

Examples of the vinyl group-containing monomer include vinyl esters such as vinyl acetate and vinyl propionate; olefins such as ethylene, propylene and isobutylene; halogenated olefins such as vinyl chloride and vinylidene chloride; styrenes such as styrene and α-methylstyrene. Monomer; Diene monomers such as butadiene, isoprene, chloroprene, etc. may be mentioned.
A monomer (a3) may be used individually by 1 type, and may use 2 or more types.

[(Meth) acrylic oligomer (B)]
The (meth) acrylic oligomer (B) has a hydrolyzable silyl group, Mw of 500 to 30,000, and Tg of 0 ° C. or higher.

Since the (meth) acrylic oligomer (B) has a relatively high Tg, the surface strength of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition containing the (B) can be increased, and high temperature and high It becomes possible to prevent the pressure-sensitive adhesive layer from being adhered or peeled off from the adherend after being placed under wet conditions. In addition, the hydrolyzable silyl group can improve the durability of the pressure-sensitive adhesive layer, particularly when a glass plate is used as an adherend, under high temperature and high humidity conditions. Unlike conventional methods in which a silane coupling agent is added to the pressure-sensitive adhesive composition, it is not hindered by a polymer having a Tg, which has a high effect of improving durability by hydrolyzable silyl groups. It is considered that a pressure-sensitive adhesive layer having excellent durability under conditions can be obtained.

(Meth) acrylic oligomer (B) can also be used as a tackifier. The tackifier consisting of (B) can form a pressure-sensitive adhesive layer excellent in durability under high temperature and high humidity conditions by being blended with the pressure-sensitive adhesive composition.

Examples of the hydrolyzable silyl group (B) include a group represented by the formula (B-1).

* -SiR ⁵ _n (O (R ⁶ O) _m R ⁷ ) _3-n (B-1)
In formula (B-1), R ⁵ is an alkyl group having 1 to 12 carbon atoms, R ⁶ is an alkylene group having 1 to 4 carbon atoms, and R ⁷ is an alkyl group having 1 to 12 carbon atoms. When there are a plurality of R ^{5 s} , R ^{6 s} and R ^{7 s} , these may be the same or different. n is an integer from 0 to 2, and m is an integer from 0 to 4. * Represents a bond.

Examples of the group represented by the formula (B-1) include a trimethoxysilyl group, a triethoxysilyl group, a methyldimethoxysilyl group, a methyldiethoxysilyl group, and a tris (2-methoxyethoxy) silyl group.

In the (meth) acrylic oligomer (B), the Mw measured by the GPC method is a polystyrene conversion value of 500 to 30,000, preferably 1,000 to 20,000, more preferably 1,500 to 10,000. It is preferable from the viewpoint of compatibility with the (meth) acrylic polymer (A) that Mw is within the above range. Moreover, when Mw is equal to or higher than the lower limit value, a sufficiently high Tg is easily obtained, and when Mw is equal to or lower than the upper limit value, it is easily compatible with the (meth) acrylic polymer (A). It becomes difficult to cause problems such as generation and deterioration of durability. If the Mw is less than 500, a sufficiently high Tg cannot be obtained.

The (meth) acrylic oligomer (B) has an Mw / Mn measured by the GPC method of preferably 7 or less, more preferably 5 or less, and even more preferably 3 or less. When Mw / Mn is within the above range, it is preferable from the viewpoint of compatibility with the (meth) acrylic polymer (A) and improvement in durability of the pressure-sensitive adhesive layer.

Tg of the (meth) acrylic oligomer (B) can be measured, for example, by a differential scanning calorimeter by the method described in the examples. The Tg of the (meth) acrylic oligomer (B) is 0 ° C. or higher, preferably 10 to 120 ° C., more preferably 20 to 100 ° C. It is preferable that Tg is within the above range because the pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition is excellent in durability under high temperature and high humidity conditions.

In the pressure-sensitive adhesive composition of the present invention, the content of the (meth) acrylic oligomer (B) is preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the (meth) acrylic polymer (A). The amount is more preferably 1 to 15 parts by mass, still more preferably 2 to 10 parts by mass. When the content of (B) is equal to or higher than the lower limit value, an effect of improving durability can be imparted to the pressure-sensitive adhesive layer. When the content is equal to or lower than the upper limit value, the adhesive layer becomes cloudy or the Tg of the pressure-sensitive adhesive layer. It is hard to produce the malfunction that adhesive force falls because it becomes too high.

As the (meth) acrylic oligomer (B), for example, (meth) acrylic oligomer (B1) having a hydrolyzable silyl group at the end of the molecule (hereinafter also referred to as “oligomer (B1)”), hydrolysis. (Meth) acrylic oligomer (B2) (hereinafter also referred to as “oligomer (B2)”) which is an oligomer of a monomer component containing a polymerizable silyl group-containing monomer.

<Oligomer (B1)>
The oligomer (B1) has a hydrolyzable silyl group at the end of the molecule.
The oligomer (B1) is preferably produced by polymerizing a monomer component in the presence of a hydrolyzable silyl group-containing chain transfer agent. By using the chain transfer agent, an oligomer (B1) having a hydrolyzable silyl group at the end of the molecule is obtained. The pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition containing the oligomer (B1) is very excellent in durability under high temperature and high humidity conditions. Further, the pressure-sensitive adhesive layer is preferable because it has good adhesive strength, and particularly has high adhesive strength after standing under high temperature and high humidity conditions.

The Tg of the oligomer (B1) is preferably 0 ° C. or higher. Therefore, it is preferable to use at least a monomer having a Tg of the homopolymer of 0 ° C. or higher as the monomer component.

Examples of the monomer having a homopolymer Tg of 0 ° C. or higher include (meth) acrylic acid alkyl ester, (meth) acrylic acid alkoxyalkyl ester, and alicyclic group-containing (meth) acrylic acid having a Tg of 0 ° C. or higher. Ester, aryl group-containing (meth) acrylic acid ester, carboxyl group-containing (meth) acrylate, ethylenically unsaturated carboxylic acid, amino group-containing (meth) acrylic acid ester, amide group-containing (meth) acrylic monomer, cyano group-containing (Meth) acrylic monomers and vinyl group-containing monomers.

Specifically, methyl (meth) acrylate, ethyl methacrylate, n-propyl (meth) acrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl (meth) acrylate, pentyl acrylate, tetradecyl acrylate, hexadecyl ( (Meth) acrylic acid alkyl esters such as meth) acrylate; (meth) acrylic acid alkoxyalkyl esters such as ethoxyethyl methacrylate; cyclohexyl (meth) acrylate, 4-tert-butylcyclohexyl (meth) acrylate, isobornyl (meth) acrylate, etc. (Meth) acrylic acid ester containing benzyl; benzyl (meth) acrylate, 2-naphthyl acrylate, phenoxyethyl methacrylate Aryl group-containing (meth) acrylic acid esters such as carboxyethyl acrylate and other carboxyl group-containing (meth) acrylates; (meth) acrylic acid, maleic acid, itaconic acid and other ethylenically unsaturated carboxylic acids; dimethylaminoethyl (meta ) Amino group-containing (meth) acrylic acid esters such as acrylates; Amide group-containing (meth) acrylic monomers such as acrylamide and dimethylacrylamide; Cyano group-containing (meth) acrylic monomers such as acrylonitrile; Vinyl acetates, vinyls such as styrene And group-containing monomers.

Among them, alicyclic group-containing (meth) acrylic acid esters are preferable from the viewpoint of easily obtaining an oligomer (B) having a Mw of 30,000 or less and having a high Tg.

As the Tg of the homopolymer, a value described in Polymer Handbook Fourth Edition (Wiley-Interscience 2003) or a manufacturer's catalog can be used.

The content of the monomer whose Tg of the homopolymer is 0 ° C. or more is preferably from the viewpoint of setting the Tg of the oligomer (B1) within the above range in 100% by mass of the monomer component used to form the oligomer (B1). Is 10% by mass or more, more preferably 30% by mass or more, and still more preferably 50% by mass or more.

Examples of the monomer component used to form the oligomer (B1) include the above-mentioned << (meth) acrylic acid alkyl ester, (meth) acrylic acid other than the monomer having a Tg of 0 ° C. or higher. Listed in the column of at least one monomer (a1) selected from alkoxyalkyl esters and alkoxypolyalkylene glycol mono (meth) acrylates, << crosslinkable group-containing monomer (a2) >> and << other monomers (a3) >> Monomers can also be used. Moreover, the hydrolyzable silyl group containing monomer as described in the column of <Oligomer (B2)> can also be used.

The kind and amount of use of the hydrolyzable silyl group-containing chain transfer agent will be described later in the section << Production conditions for (meth) acrylic polymer (A) and (meth) acrylic oligomer (B) >>.

<Oligomer (B2)>
The oligomer (B2) is a polymer of monomer components including a hydrolyzable silyl group-containing monomer. Since the oligomer (B2) has a structural unit derived from a hydrolyzable silyl group-containing monomer, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition containing the oligomer (B2) is durable under high temperature and high humidity conditions. Good properties.

Examples of the hydrolyzable silyl group-containing monomer include a hydrolyzable silyl group-containing (meth) acrylic monomer represented by the formula (B2-1) and a hydrolyzable silyl group-containing monomer represented by the formula (B2-2) A vinyl monomer is mentioned.

CH ₂ = CR ⁸ —COO—R ⁹ —R ^(B-1) (B2-1)
CH ₂ = CH—R ¹⁰ —R ^(B-1) (B2-2)
In the formula (B2-1), R ⁸ is a hydrogen atom or a methyl group, R ⁹ is an alkylene group having 1 to 12 carbon atoms, and R ^(B-1) is represented by the formula (B-1). Group.

In the formula (B2-2), R ¹⁰ is a direct bond or an alkylene group having 1 to 12 carbon atoms, and R ^(B-1) is a group represented by the formula (B-1).

Examples of hydrolyzable silyl group-containing (meth) acrylic monomers include 3- (meth) acryloxypropylmethyldimethoxysilane, 3- (meth) acryloxypropylmethyldiethoxysilane, and 3- (meth) acryloxypropyl. Examples include trimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, and 3- (meth) acryloxyoctyltrimethoxysilane.

Examples of the hydrolyzable silyl group-containing vinyl monomer include vinyltrimethoxysilane, vinyltriethoxysilane, octenyltrimethoxysilane, and vinyltris (2-methoxyethoxy) silane.
One hydrolyzable silyl group-containing monomer may be used alone, or two or more hydrolyzable silyl group-containing monomers may be used.

The content of the hydrolyzable silyl group-containing monomer is preferably 1 to 90% by mass, more preferably 3 to 50% by mass, and still more preferably 100% by mass of the monomer component used to form the oligomer (B2). 4 to 30% by mass. It is preferable that the content of the hydrolyzable silyl group-containing monomer is within the above range because of excellent compatibility and durability under high temperature and high humidity conditions.

The Tg of the oligomer (B2) is preferably 0 ° C. or higher. Therefore, it is preferable to use at least a monomer having a Tg of the homopolymer of 0 ° C. or higher as the monomer component.

Examples of the monomer having a Tg of the homopolymer of 0 ° C. or higher include monomers described in the section <Oligomer (B1)>.

The content of the monomer whose Tg of the homopolymer is 0 ° C. or higher is preferably from the viewpoint of setting the Tg of the oligomer (B2) within the above range in 100% by mass of the monomer component used to form the oligomer (B2). Is 10% by mass or more, more preferably 30% by mass or more, and still more preferably 50% by mass or more.

Examples of the monomer component used to form the oligomer (B2) include, in addition to the above-mentioned hydrolyzable silyl group-containing monomer and the monomer having a Tg of 0 ° C. or higher, the above-mentioned << (meth) acrylic acid At least one monomer (a1) selected from alkyl ester, alkoxyalkyl ester of (meth) acrylic acid and alkoxypolyalkylene glycol mono (meth) acrylate, << crosslinkable group-containing monomer (a2) >> and << other monomers ( a3) >> can also be used.

<< Production conditions for (meth) acrylic polymer (A) and (meth) acrylic oligomer (B) >>
The (meth) acrylic polymer (A) and the (meth) acrylic oligomer (B) are produced by a conventionally known polymerization method such as a solution polymerization method, a bulk polymerization method, an emulsion polymerization method, or a suspension polymerization method. Among these, the solution polymerization method is preferable.

Specifically, a monomer component and, if necessary, a chain transfer agent, a polymerization solvent, and the like are charged in a reaction vessel. For example, a polymerization initiator is added under an inert gas atmosphere such as nitrogen gas, and the reaction start temperature is set. The reaction system is maintained at a temperature of usually 40 to 100 ° C., preferably 50 to 80 ° C., usually 50 to 90 ° C., preferably 60 to 90 ° C., and allowed to react for 2 to 20 hours.

Examples of the chain transfer agent include hydrolyzable silyl group-containing chain transfer agents and other chain transfer agents. In the production of the oligomer (B1), it is preferable to use a hydrolyzable silyl group-containing chain transfer agent.

The hydrolyzable silyl group-containing chain transfer agent is represented, for example, by the formula (B1-1).
HS-R ¹¹ -R ^(B-1) (B1-1)
In the formula (B1-1), R ¹¹ is an alkylene group having 1 to 12 carbon atoms, and R ^(B-1) is a group represented by the formula (B-1).
Examples of the chain transfer agent represented by the formula (B1-1) include 3-mercaptopropyltrimethoxysilane and 3-mercaptopropylmethyldimethoxysilane.

Examples of other chain transfer agents include monofunctional thiols such as n-dodecyl mercaptan, polyfunctional thiols such as pentaerythritol tetrakis (3-mercaptopropionate), α-methylstyrene dimer (2,4-diphenyl). Styrene dimers such as -4-methyl-1-pentene) and quinoexters. “Kino Exter” is a trade name of Kawasaki Kasei Kogyo Co., Ltd.

A chain transfer agent may be used individually by 1 type, and may use 2 or more types.
The chain transfer agent is preferably 0.1 to 40 parts by weight, more preferably 1 to 20 parts by weight, still more preferably 5 to 15 parts by weight based on 100 parts by weight of the monomer component used to form the oligomer (B). Used in amounts in the range of parts by weight.

Examples of the polymerization initiator include azo initiators and peroxide polymerization initiators.
Examples of the azo initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2- Cyclopropylpropionitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane-1-carbohydrate) Nitrile), 2- (carbamoylazo) isobutyronitrile, 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′- Azobis (N, N'-dimethyleneisobutylamidine), 2,2'-azobis [2-methyl-N- (2-hydroxyethyl) -propionamide], 2,2'-azo (Isobutylamide) dihydrate, 4,4′-azobis (4-cyanopentanoic acid), 2,2′-azobis (2-cyanopropanol), dimethyl-2,2′-azobis (2-methylpropionate) An azo compound such as

Examples of peroxide polymerization initiators include t-butyl hydroperoxide, cumene hydroxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, and di-i-propyl peroxydicarbonate. , Di-2-ethylhexyl peroxydicarbonate, t-butyl peroxybivalate, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane, 2,2-bis (4,4- Di-t-amylperoxycyclohexyl) propane, 2,2-bis (4,4-di-t-octylperoxycyclohexyl) propane, 2,2-bis (4,4-di-α-cumylperoxycyclohexyl) ) Propane, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) ) Butane, 2,2-bis (4,4-di -t- octylperoxycarbonyl cyclohexyl), and butane.

A polymerization initiator may be used individually by 1 type, and may use 2 or more types.
In the production of the (meth) acrylic polymer (A), the polymerization initiator is usually 0.001 to 5 parts by weight, preferably 100 parts by weight, preferably 100 parts by weight of the monomer component used to form the (A). Used in an amount in the range of 0.005 to 3 parts by mass.
In the production of the (meth) acrylic oligomer (B), the polymerization initiator is preferably 0.1 to 2.0 parts by mass with respect to 100 parts by mass of the monomer component used to form the (B). More preferably, it is used in an amount in the range of 0.2 to 1.0 part by mass.

Examples of the polymerization solvent used for the solution polymerization include aromatic hydrocarbons such as benzene, toluene and xylene; aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane and n-octane; cyclopentane, cyclohexane, Cycloaliphatic hydrocarbons such as cycloheptane and cyclooctane; ethers such as diethyl ether, diisopropyl ether, 1,2-dimethoxyethane, dibutyl ether, tetrahydrofuran, dioxane, anisole, phenylethyl ether, diphenyl ether; chloroform, carbon tetrachloride, Halogenated hydrocarbons such as 1,2-dichloroethane and chlorobenzene; esters such as ethyl acetate, propyl acetate, butyl acetate and methyl propionate; acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, Ketones such as hexanone; acetonitrile, nitriles such as benzonitrile;; N, N- dimethylformamide, N, N- dimethylacetamide, amides such as N- methylpyrrolidone dimethyl sulfoxide, sulfoxides such sulfolane.

A polymerization solvent may be used individually by 1 type, and may use 2 or more types.
Moreover, you may add suitably a polymerization initiator, a chain transfer agent, a monomer component, and a polymerization solvent during a polymerization reaction.

[Crosslinking agent (C)]
The pressure-sensitive adhesive composition of the present invention preferably contains a crosslinking agent (C). The crosslinking agent (C) is appropriately selected depending on the crosslinkable group that can be introduced into the (meth) acrylic polymer (A), and for example, an isocyanate compound, an epoxy compound, or a metal chelate compound can be used.

By crosslinking the (meth) acrylic polymer (A) with the crosslinking agent (C), a crosslinked body (network polymer) can be formed, and an adhesive layer having excellent heat resistance can be obtained.
A crosslinking agent (C) may be used individually by 1 type, and may use 2 or more types.

In the pressure-sensitive adhesive composition of the present invention, the content of the crosslinking agent (C) is preferably 0.1 to 20 parts by mass, more preferably 0, relative to 100 parts by mass of the (meth) acrylic polymer (A). 1 to 12 parts by mass, more preferably 0.2 to 4 parts by mass.

As the isocyanate compound, an isocyanate compound having 2 or more isocyanate groups in one molecule is usually used, preferably 2 to 8, and more preferably 3 to 6. When the number of isocyanate groups is within the above range, it is preferable from the viewpoint of the crosslinking reaction efficiency between the (meth) acrylic polymer (A) and the isocyanate compound and the flexibility of the pressure-sensitive adhesive layer.

Examples of the diisocyanate compound having 2 isocyanate groups in one molecule include aliphatic diisocyanate, alicyclic diisocyanate, and aromatic diisocyanate. Aliphatic diisocyanates include ethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2-methyl-1,5-pentane diisocyanate, 3-methyl-1,5-pentane diisocyanate, 2,2,4-trimethyl And aliphatic diisocyanates having 4 to 30 carbon atoms such as -1,6-hexamethylene diisocyanate. Examples of the alicyclic diisocyanate include 7 to 30 carbon atoms such as isophorone diisocyanate, cyclopentyl diisocyanate, cyclohexyl diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and hydrogenated tetramethylxylene diisocyanate. Diisocyanate is mentioned. Examples of the aromatic diisocyanate include aromatic diisocyanates having 8 to 30 carbon atoms such as phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, naphthylene diisocyanate, diphenyl ether diisocyanate, diphenylmethane diisocyanate, and diphenylpropane diisocyanate.

Examples of the isocyanate compound having 3 or more isocyanate groups in one molecule include aromatic polyisocyanate, aliphatic polyisocyanate, and alicyclic polyisocyanate. Specific examples include 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, and 4,4 ', 4 "-triphenylmethane triisocyanate.

Examples of the isocyanate compound include multimers (for example, dimers or trimers, biurets, and isocyanurates) and derivatives (for example, polyhydric alcohols) of the above isocyanate compounds having 2 or 3 isocyanate groups. Addition reaction product with two or more diisocyanate compounds) and polymer. Examples of the polyhydric alcohol in the derivative include trivalent or higher alcohols such as trimethylolpropane, glycerin and pentaerythritol as low molecular weight polyhydric alcohols; high molecular weight polyhydric alcohols such as polyether polyols, Examples include polyester polyol, acrylic polyol, polybutadiene polyol, and polyisoprene polyol.

Examples of such isocyanate compounds include diphenylmethane diisocyanate trimer, polymethylene polyphenyl polyisocyanate, hexamethylene diisocyanate or tolylene diisocyanate biuret or isocyanurate, trimethylolpropane and tolylene diisocyanate or xylylene diisocyanate. Reaction product (for example, a trimolecular adduct of tolylene diisocyanate or xylylene diisocyanate), a reaction product of trimethylolpropane and hexamethylene diisocyanate (for example, a trimolecular adduct of hexamethylene diisocyanate), a polyether polyisocyanate, Polyester polyisocyanate is mentioned.

Among the isocyanate compounds, xylylene diisocyanate-based and tolylene diisocyanate-based crosslinking agents are preferable from the viewpoint of difficult yellowing.

Examples of the epoxy compound include compounds having two or more epoxy groups in the molecule. For example, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexane. Diol diglycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, diamine glycidyl amine, N, N, N ', N'-tetraglycidyl-m-xylylenediamine, 1,3-bis (N, N'- Diamine glycidylaminomethyl).

As the metal chelate compound, for example, an alkoxide, acetylacetone, ethyl acetoacetate or the like is coordinated to a polyvalent metal such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium. Compounds. Specific examples include aluminum isopropylate, aluminum secondary butyrate, aluminum ethyl acetoacetate / diisopropylate, aluminum trisethyl acetoacetate, and aluminum trisacetylacetonate.

[Additive (D)]
The pressure-sensitive adhesive composition of the present invention includes, in addition to the above components, a silane coupling agent, an antistatic agent, an antioxidant, a light stabilizer, a metal corrosion inhibitor, and (B) as long as the effects of the present invention are not impaired. 1 type, or 2 or more types of additives selected from tackifiers, plasticizers, crosslinking accelerators, surfactants, (meth) acrylic polymers other than (A) and (B), and rework agents You may contain.

[Organic solvent (E)]
The pressure-sensitive adhesive composition of the present invention preferably contains an organic solvent (E) in order to adjust its applicability. Examples of the organic solvent (E) include the polymerization solvents described in the section << Production conditions for (meth) acrylic polymer (A) and (meth) acrylic oligomer (B) >>. In the pressure-sensitive adhesive composition of the present invention, the content of the organic solvent is usually 30 to 90% by mass, preferably 40 to 90% by mass.

In the present specification, “solid content” refers to all components excluding the organic solvent (E) among the components contained in the pressure-sensitive adhesive composition, and “solid content concentration” refers to the pressure-sensitive adhesive composition 100. The ratio of the said solid content with respect to the mass% is said.
In the pressure-sensitive adhesive composition of the present invention, the total amount of the (meth) acrylic polymer (A) and the (meth) acrylic oligomer (B) is usually 80% by mass or more, preferably 90% by mass in a solid content of 100% by mass. % Or more, more preferably 95% by mass or more. The upper limit of the total amount can be appropriately determined depending on the amount of other components such as the crosslinking agent (C).

[Preparation of pressure-sensitive adhesive composition]
In the pressure-sensitive adhesive composition of the present invention, for example, the (meth) acrylic polymer (A), the (meth) acrylic oligomer (B), and other components as necessary are mixed by a conventionally known method. Can be prepared. For example, obtained when synthesizing a solution containing (meth) acrylic polymer (A) obtained when synthesizing (meth) acrylic polymer (A) and (meth) acrylic oligomer (B). A pressure-sensitive adhesive composition can be prepared by mixing a solution containing the (meth) acrylic oligomer (B) and other components as necessary.

Moreover, the monomer component which forms (meth) acrylic-type polymer (A) is added to the solution containing (meth) acrylic-type oligomer (B), polymerization reaction is performed, and other components are added as needed. The pressure-sensitive adhesive composition can also be prepared.

(Adhesive layer)
The pressure-sensitive adhesive layer is formed from the above-mentioned pressure-sensitive adhesive composition. For example, the pressure-sensitive adhesive layer can be obtained by proceeding with the crosslinking reaction in the above-mentioned pressure-sensitive adhesive composition, specifically, by crosslinking the (meth) acrylic polymer (A) with the crosslinking agent (C).

The conditions for forming the pressure-sensitive adhesive layer are, for example, as follows. The pressure-sensitive adhesive composition of the present invention is applied on a support and varies depending on the type of solvent, but is usually 50 to 150 ° C., preferably 60 to 100 ° C., usually 1 to 10 minutes, preferably 2 to 7 minutes. Then, the solvent is removed and a coating film is formed. The film thickness of the dried coating film is usually 5 to 75 μm, preferably 10 to 50 μm.

The pressure-sensitive adhesive layer is preferably formed under the following conditions. After applying the pressure-sensitive adhesive composition of the present invention on a support and applying a cover film on the coating film formed under the above conditions, usually 3 days or more, preferably 7 to 10 days, usually 5 to 60 ° C., It is preferably cured in an environment of 15 to 40 ° C., usually 30 to 70% RH, preferably 40 to 70% RH. When crosslinking is performed under the aging conditions as described above, a crosslinked body (network polymer) can be efficiently formed.

As a method for applying the pressure-sensitive adhesive composition, a known thickness such as a spin coating method, a knife coating method, a roll coating method, a bar coating method, a blade coating method, a die coating method, or a gravure coating method may be used. The method of applying and drying can be used.

Examples of the support and cover film include polyester films such as polyethylene terephthalate (PET); plastic films such as polyolefin films such as polyethylene, polypropylene, and ethylene-vinyl acetate copolymer.

The pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention has a gel fraction of preferably 60 to 100% by mass, more preferably from the viewpoints of distortion suppression, cohesive strength, adhesive strength, and removability of the polarizing plate. Is 65 to 95% by mass, more preferably 70 to 90% by mass.
The pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention is excellent in durability under high temperature and high humidity conditions.

[Plastic adhesive sheet]
The pressure-sensitive adhesive sheet for polarizing plates of the present invention has a pressure-sensitive adhesive layer formed from the above-mentioned pressure-sensitive adhesive composition. Examples of the pressure-sensitive adhesive sheet include a double-sided pressure-sensitive adhesive sheet having only the pressure-sensitive adhesive layer, a base material, and a double-sided pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer formed on both surfaces of the base material, the base material, and one of the base materials. Examples thereof include a single-sided pressure-sensitive adhesive sheet having the above-mentioned pressure-sensitive adhesive layer formed on the surface, and a pressure-sensitive adhesive sheet having a peel-treated cover film attached to the surface of the pressure-sensitive adhesive sheet that is not in contact with the base material.

Examples of the substrate and cover film include polyester films such as polyethylene terephthalate (PET); plastic films such as polyolefin films such as polyethylene, polypropylene, and ethylene-vinyl acetate copolymer.

The conditions for forming the pressure-sensitive adhesive layer and the gel fraction are the same as the conditions described in the column [Pressure-sensitive adhesive layer].
The thickness of the pressure-sensitive adhesive layer is usually 5 to 75 μm, preferably 10 to 50 μm, from the viewpoint of maintaining adhesive performance. The film thickness of the substrate and the cover film is not particularly limited, but is usually 10 to 125 μm, preferably 25 to 75 μm.

[Polarizing plate with adhesive layer and laminate]
The polarizing plate with an adhesive layer has a polarizing plate and the adhesive layer formed from the adhesive composition of this invention in the at least one surface of the said polarizing plate. In this specification, “polarizing plate” is used to include “polarizing film”.

As the polarizing plate, a conventionally known polarizing plate can be used, and examples thereof include a polarizing plate having a polarizer and a polarizer protective film disposed on one side or both sides of the polarizer.

Examples of the polarizer include a stretched film obtained by adding a polarizing component to a film made of a polyvinyl alcohol resin and stretching the film. Examples of the polyvinyl alcohol-based resin include polyvinyl alcohol, polyvinyl formal, polyvinyl acetal, and a saponified product of an ethylene / vinyl acetate copolymer. Examples of the polarization component include iodine or a dichroic dye.

Examples of the polarizer protective film include films made of cellulose such as triacetyl cellulose and diacetyl cellulose, polycarbonate films, and polyether sulfone films. In the present invention, even when a cellulose film is used as the polarizer protective film and the pressure-sensitive adhesive layer is formed in contact with the cellulose film, the long-term reliability, specifically, wet heat resistance is excellent.

The thickness of the polarizing plate is preferably 30 to 250 μm, more preferably 50 to 200 μm.
The method for forming the pressure-sensitive adhesive layer on the surface of the polarizing plate is not particularly limited. The method for applying the pressure-sensitive adhesive composition directly on the surface of the polarizing plate using a bar coater and drying and aging, the pressure-sensitive adhesive sheet for polarizing plate of the present invention There is a method in which the pressure-sensitive adhesive layer possessed by is transferred to the polarizing plate surface and aged. The conditions for drying and aging, the gel fraction, and the like are the same as the conditions described in the [Adhesive layer] column.

The thickness of the pressure-sensitive adhesive layer formed on the polarizing plate is preferably 5 to 75 μm, more preferably 10 to 50 μm in terms of dry film thickness. In addition, the adhesive layer should just be formed in at least one surface of a polarizing plate, the aspect in which an adhesive layer is formed only in the single side | surface of a polarizing plate, the aspect in which an adhesive layer is formed in both surfaces of a polarizing plate Is mentioned.

Moreover, the layer which has other functions, such as a glare-proof layer, a phase difference layer, a viewing angle improvement layer, may be laminated | stacked on the said polarizing plate, for example.
A liquid crystal element is produced by providing the polarizing plate with the pressure-sensitive adhesive layer of the present invention obtained as described above on the substrate surface of the liquid crystal cell. Here, the liquid crystal cell has a structure in which a liquid crystal layer is sandwiched between two substrates.

A laminate in which a polarizing plate, a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention, and a glass substrate are laminated in this order can also be produced.
As a board | substrate which a liquid crystal cell has, glass plates, such as an alkali glass plate, are mentioned, for example. The thickness of the substrate is preferably 5 mm or less, more preferably 0.05 to 2 mm.

Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to these examples. In the following description of Examples and the like, “part” means “part by mass” unless otherwise specified.

The measuring method of physical properties is as follows.
[GPC]
For the (meth) acrylic polymer and the (meth) acrylic oligomer, the weight average molecular weight (Mw) and the number average molecular weight (Mn) were determined by gel permeation chromatography (GPC method) under the following conditions.
・ Measurement device: HLC-8320GPC (manufactured by Tosoh Corporation)
-GPC column configuration: The following four columns (all manufactured by Tosoh Corporation)
(1) TSKgel HxL-H (guard column)
(2) TSKgel GMHxL
(3) TSKgel GMHxL
(4) TSKgel G2500HxL
・ Flow rate: 1.0 mL / min
-Column temperature: 40 ° C
Sample concentration: 1.5% (w / v) (diluted with tetrahydrofuran)
・ Mobile phase solvent: Tetrahydrofuran ・ Standard polystyrene conversion

[Glass transition temperature (Tg)]
A (meth) acrylic polymer or (meth) acrylic oligomer was sealed in a simple airtight pan, and measurement was performed using a differential scanning calorimeter (DSC). Measurement was performed at 10 ° C./min. From −100 ° C. to 200 ° C. under a nitrogen stream. Then, the temperature change was measured by heating, and a graph of “endothermic heat generation” and “temperature” was drawn, and the characteristic inflection observed at this time was defined as Tg. In addition, the value obtained by the midpoint method from DSC curve was used for Tg.

[Synthesis Example A-1]
A flask equipped with a stirrer, nitrogen gas inlet tube, thermometer and reflux condenser was charged with 95 parts of n-butyl acrylate, 4 parts of 2-hydroxyethyl acrylate, 1 part of acrylic acid, 80 parts of methyl ethyl ketone and 25 parts of ethyl acetate. The contents of the flask were heated to 70 ° C. while introducing nitrogen gas into the flask. Next, 0.05 part of 2,2′-azobisisobutyronitrile (hereinafter also referred to as “AIBN”) was added to the flask with stirring. Heating and cooling were performed for 2.5 hours so that the temperature of the contents in the flask could be maintained at 70 ° C. After raising the temperature to 80 ° C., a reflux reaction was conducted for 2 hours to obtain a (meth) acrylic polymer (A-1). After completion of the reaction, the mixture was diluted with a mixed solution of methyl ethyl ketone and ethyl acetate (80 parts: 25 parts) to prepare a polymer solution containing a (meth) acrylic polymer (A-1) having a solid content concentration of 45% by mass. With respect to the obtained (A-1), Mw measured by GPC was 300,000, and the dispersion index (Mw / Mn) was 3.6. The Tg was −50 ° C.

[Synthesis Example B-1]
In a flask equipped with a stirrer, a nitrogen gas inlet tube, a thermometer, and a reflux condenser, 100 parts of isobornyl methacrylate and 10 parts of 3-mercaptopropyltrimethoxysilane (trade name: KBM-803, manufactured by Shin-Etsu Chemical Co., Ltd.) Then, 200 parts of ethyl acetate was charged, and the contents of the flask were heated to 75 ° C. while introducing nitrogen gas into the flask.

After sufficiently replacing nitrogen gas in the flask, 0.2 part of AIBN was added to the flask with stirring. After 30 minutes, 0.2 part of AIBN was further added, and the temperature was raised to 80 ° C. After further 30 minutes, 0.2 part of AIBN was added and a reflux reaction was performed for 4 hours to obtain a (meth) acrylic oligomer (B-1). After completion of the reaction, the reaction mixture was diluted with ethyl acetate to prepare an oligomer solution containing a (meth) acrylic oligomer (B-1) having a solid content concentration of 35% by mass. With respect to the obtained (B-1), Mw measured by GPC was 3,000, and Mw / Mn was 1.7. Moreover, Tg was 60 degreeC.

[Synthesis Examples B-2 to B-10]
(Meth) acrylic oligomers (B-2) to (B-10) were produced in the same manner as in Synthesis Example B-1, except that the raw materials shown in Table 1 were used.

[Example 1]
(1) Preparation of pressure-sensitive adhesive composition The polymer solution obtained in Synthesis Example A-1 (solid content concentration 45% by mass) and the oligomer solution obtained in Synthesis Example B-1 (solid content concentration 35% by mass) TD-75 (manufactured by Soken Chemical Co., Ltd .: xylene diisocyanate-based cross-linking agent, solid content concentration of 75% by mass) as a cross-linking agent, with a solid content ratio of (A-1) 100 parts and (B-1) 4 parts, respectively. , (TD-75) was mixed in an amount of 0.8 part to obtain an adhesive composition.

(2) Production of polarizing plate with pressure-sensitive adhesive The pressure-sensitive adhesive composition obtained in (1) above was peeled off from the polyethylene terephthalate film (PET film) subjected to the release treatment, and the liquid temperature was 25 using a doctor blade. The pressure-sensitive adhesive sheet was coated at 90 ° C. and dried at 90 ° C. for 3 minutes to obtain a pressure-sensitive adhesive sheet having a dry film thickness of 20 μm. The sheet and the polarizing plate (thickness: 110 μm, layer structure: triacetyl cellulose film / polyvinyl alcohol film / triacetyl cellulose film) were bonded together so that the coating film and the polarizing plate were in contact with each other, and 23 ° C./50%. The plate was allowed to stand and matured for 7 days under the conditions of RH to obtain a polarizing plate with a pressure-sensitive adhesive layer having a PET film, a pressure-sensitive adhesive layer having a thickness of 20 μm, and a polarizing plate.

[Examples 2 to 5 and Comparative Examples 1 to 6]
In Example 1, the adhesive composition, the adhesive sheet, and the polarizing plate with an adhesive layer were obtained like Example 1 except having changed the compounding composition as described in Table 2.

[Evaluation]
〔appearance〕
The appearance of the pressure-sensitive adhesive layer of the polarizing plate with the pressure-sensitive adhesive layer obtained in Examples and Comparative Examples was evaluated by visual observation based on the following criteria.
AA: cloudiness and foreign matter were not confirmed CC: cloudiness or foreign matter was confirmed

[Durability test]
A polarizing plate with a pressure-sensitive adhesive layer obtained in Examples and Comparative Examples (a laminate comprising PET film / pressure-sensitive adhesive layer / polarizing plate) was cut into a size of 150 mm × 250 mm to prepare a test piece. The PET film is peeled off from the test piece, and the laminate composed of the pressure-sensitive adhesive layer / polarizing plate is pasted on one side of the 2 mm-thick alkali glass plate using a laminator roll so that the pressure-sensitive adhesive layer and the alkali glass plate are in contact with each other. I wore it. The obtained laminate was held in an autoclave adjusted to 50 ° C./5 atm for 20 minutes to prepare a test plate. The test plate was left in an environment of 60 ° C./90% RH for 500 hours. Appearance defects such as foaming from the pressure-sensitive adhesive layer of the test plate, cracks in the test plate, and peeling of the pressure-sensitive adhesive layer were visually observed and evaluated according to the following criteria.

(Standard)
-AA: appearance defect occurrence area 0%
-BB: appearance defect occurrence area exceeding 0% and less than 3%-CC: appearance defect occurrence area 3% or more and less than 5%-DD: appearance defect occurrence area 5% or more

[Adhesion test]
A polarizing plate with a pressure-sensitive adhesive layer (a laminate comprising PET film / pressure-sensitive adhesive layer / polarizing plate) obtained in Examples and Comparative Examples was cut into a size of 25 mm × 70 mm to prepare a test piece. The PET film is peeled off from the test piece, and the laminate composed of the pressure-sensitive adhesive layer / polarizing plate is pasted on one side of the 2 mm-thick alkali glass plate using a laminator roll so that the pressure-sensitive adhesive layer and the alkali glass plate are in contact with each other. I wore it. The obtained laminate was held in an autoclave adjusted to 50 ° C./5 atm for 20 minutes to prepare a test plate. Two similar test plates were prepared for each polarizing plate with an adhesive layer.

One test plate was allowed to stand for 30 minutes in an atmosphere of 23 ° C./50% RH. Thereafter, a peeling test was performed with a tensile tester at a peeling rate of 300 mm / min and 90 ° peeling, and the obtained adhesion strength value was defined as an initial adhesive strength.

The other test plate was stored in a 60 ° C./95% RH atmosphere for 100 hours and then allowed to stand in a 23 ° C./50% RH atmosphere for 48 hours. Thereafter, a peeling test was performed with a tensile tester at a peeling rate of 300 mm / min and 90 ° peeling, and the obtained adhesion strength value was defined as an adhesive strength after heat and moisture resistance.

Each component described in Table 2 is as shown below.
TD-75: Xylene diisocyanate crosslinking agent (manufactured by Soken Chemical Co., Ltd., trade name)
A-50: Silane coupling (SiC) agent (manufactured by Soken Chemical Co., Ltd., trade name)

Claims

A (meth) acrylic polymer (A) having a glass transition temperature (Tg) of less than 0 ° C .;
A pressure-sensitive adhesive composition comprising a (meth) acrylic oligomer (B) having a hydrolyzable silyl group, a weight average molecular weight (Mw) of 500 to 30,000, and a Tg of 0 ° C. or higher.
The pressure-sensitive adhesive composition according to claim 1, wherein the Mw of the (meth) acrylic oligomer (B) is 1,000 to 20,000.
The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the (meth) acrylic oligomer (B) has a hydrolyzable silyl group at the end of the molecule.
The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the (meth) acrylic oligomer (B) is an oligomer of a monomer component containing a hydrolyzable silyl group-containing monomer.
The monomer component is polymerized in the presence of a hydrolyzable silyl group-containing chain transfer agent, the weight average molecular weight (Mw) is 500 to 30,000, and the glass transition temperature (Tg) is 0 ° C. or higher (meth). Including a step of producing an acrylic oligomer (B),
The manufacturing method of the adhesive composition containing (meth) acrylic-type polymer (A) whose Tg is less than 0 degreeC, and (meth) acrylic-type oligomer (B).
A monomer component containing a hydrolyzable silyl group-containing monomer is polymerized, and a (meth) acrylic oligomer having a weight average molecular weight (Mw) of 500 to 30,000 and a glass transition temperature (Tg) of 0 ° C. or higher ( B) comprising the steps of:
The manufacturing method of the adhesive composition containing (meth) acrylic-type polymer (A) whose Tg is less than 0 degreeC, and (meth) acrylic-type oligomer (B).
A pressure-sensitive adhesive sheet for a polarizing plate having a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to any one of claims 1 to 4.
A polarizing plate with a pressure-sensitive adhesive layer, comprising: a polarizing plate; and a pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition according to any one of claims 1 to 4 on at least one surface of the polarizing plate.
A laminate in which a polarizing plate, an adhesive layer formed from the adhesive composition according to any one of claims 1 to 4 and a glass substrate are laminated in this order.