KR20220062091A - Pressure-sensitive adhesive composition, pressure-sensitive adhesive sheet and optical member - Google Patents

Abstract

One embodiment of the present invention provides a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer excellent in various properties such as blister resistance and whitening resistance, rework resistance, and adhesive strength in a high-temperature, high-humidity environment. One embodiment of the present invention relates to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet or an optical member, wherein the pressure-sensitive adhesive composition contains 50 to 97 mass% of an alkoxyalkyl (meth)acrylate (a1) and a carboxyl group or acid anhydride group-containing monomer (a2) ) is a copolymer of a (meth)acrylic copolymer (A), which is a copolymer of a monomer component containing 3 to 10% by mass, and a monomer component containing 1 to 10% by mass of an amino group-containing monomer (b1), and the glass transition temperature is It is a pressure-sensitive adhesive composition containing a (meth)acrylic copolymer (B) and a crosslinking agent (C) above 0 ° C., with respect to 100 parts by mass of the (meth)acrylic copolymer (A), the (meth)acrylic copolymer (B) ) contains 2 to 19 parts by mass.

Description

Pressure-sensitive adhesive composition, pressure-sensitive adhesive sheet and optical member

One embodiment of the present invention relates to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet, or an optical member.

In recent years, the market of various electronic devices equipped with a touch panel is expanding. A touch panel is a laminated body of various materials, The adhesive composition is used for bonding of the said various materials. The development of the touch panel to in-vehicle device use is also expanding, and in this use, depending on the reason that the touch panel is placed under a high temperature and high humidity environment in summer, the pressure-sensitive adhesive composition for this use is required to have more moisture and heat resistance than general use. Various pressure-sensitive adhesive compositions have been conventionally studied (for example, refer to Patent Documents 1 and 2).

Japanese Patent Application Laid-Open No. 2018-1615 Japanese Patent Laid-Open No. 2014-5387

In the above-mentioned uses, etc., the adhesive composition excellent in various properties, such as blister resistance, whitening resistance, and adhesiveness, is calculated|required. One embodiment of the present invention provides a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer excellent in various properties such as blister resistance, whitening resistance and adhesive strength in a high-temperature, high-humidity environment.

MEANS TO SOLVE THE PROBLEM The present inventors earnestly examined in order to solve the said subject. As a result, it discovered that the adhesive composition which has the following structures can solve the said subject, and came to complete this invention.

The present invention relates to, for example, the following [1] to [5].

[1] (meth)acrylic copolymer ( A) and

A (meth)acrylic copolymer (B) that is a copolymer of a monomer component containing 1 to 10% by mass of an amino group-containing monomer (b1), and has a glass transition temperature of 0° C. or higher;

Crosslinking agent (C)

It is a pressure-sensitive adhesive composition containing,

The adhesive composition containing 2-19 mass parts of said (meth)acrylic-type copolymers (B) with respect to 100 mass parts of said (meth)acrylic-type copolymers (A).

[2] The pressure-sensitive adhesive composition according to [1], wherein the (meth)acrylic copolymer (B) has a weight average molecular weight of 10,000 to 50,000.

[3] The pressure-sensitive adhesive composition according to [1] or [2], wherein the cross-linking agent (C) is an epoxy-based cross-linking agent (C1).

[4] An adhesive sheet having a pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition according to any one of [1] to [3].

[5] An optical member having an adhesive layer obtained from the pressure-sensitive adhesive composition according to any one of [1] to [3].

According to one embodiment of the present invention, a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer having excellent performance such as blister resistance, whitening resistance and adhesive strength under a high-temperature and high-humidity environment such as 85°C/85%RH (relative humidity). can provide

In this specification, acryl and methacryl are collectively referred to as "(meth)acryl", and acrylate and methacrylate are also generically described as "(meth)acrylate".

[Adhesive composition]

The pressure-sensitive adhesive composition according to one embodiment of the present invention is a (meth)acrylic copolymer (A) (also simply referred to as “copolymer (A)”) to be described below, and a (meth)acrylic copolymer (B) (simply It is also called "copolymer (B)") and a crosslinking agent (C) is contained.

The total content of the copolymer (A), the copolymer (B), and the crosslinking agent (C) in the pressure-sensitive adhesive composition is usually 60% by mass or more, preferably 65% by mass or more, more preferably in 100% by mass of the solid content of the pressure-sensitive adhesive composition. is 70 mass % or more. The solid content is a component excluding the organic solvent.

<(meth)acrylic copolymer (A)>

The (meth)acrylic copolymer (A) is a copolymer of a monomer component containing 50 to 97% by mass of an alkoxyalkyl (meth)acrylate (a1) and 3 to 10% by mass of a monomer (a2) containing a carboxyl group or an acid anhydride group and is obtained by copolymerizing the monomer component.

The monomer component usually consists of a polymerizable double bond-containing monomer.

A copolymer (A) can use 1 type or 2 or more types.

≪Alkoxyalkyl (meth)acrylate (a1)≫

By using the copolymer (A) having a structural unit derived from an alkoxyalkyl (meth)acrylate (a1) as a main component, the absorbency of the pressure-sensitive adhesive layer obtained is improved, and the moisture absorbed in the pressure-sensitive adhesive layer under a high-humidity environment is stored in the pressure-sensitive adhesive layer. It is dispersed in the , and it is possible to suppress the whitening phenomenon derived from moisture, and also it is possible to suppress the blistering phenomenon. When the pressure-sensitive adhesive layer according to one embodiment of the present invention is formed on an adherend having high moisture permeability such as a polycarbonate substrate, moisture resulting from the adherend can be dissolved and trapped in the pressure-sensitive adhesive layer, so the above effect is more tends to be prominent.

Moreover, by using the copolymer (A) which has as a main component the structural unit derived from an alkoxyalkyl (meth)acrylate (a1), the wettability to the to-be-adhered body surface of the adhesive layer obtained falls, and the adhesive force immediately after sticking is suppressed low. There exists a tendency for the rework property of an adhesive sheet to also improve by becoming.

Carbon number of the alkoxyalkyl group in alkoxyalkyl (meth)acrylate (a1) is 2-18 normally, Preferably it is 2-12, More preferably, it is 2-10. As the alkoxyalkyl (meth)acrylate (a1), for example, methoxymethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, and 4-ethoxybutyl (meth)acrylate are mentioned.

The copolymer (A) may have a structural unit derived from one or more alkoxyalkyl (meth)acrylates (a1).

The amount of alkoxyalkyl (meth)acrylate (a1) in all the monomer components used in order to obtain a copolymer (A) is 50-97 mass %, Preferably it is 55-96 mass %, More preferably, it is 60-95 mass %am. If the amount of alkoxyalkyl (meth)acrylate (a1) is equal to or greater than the lower limit, moisture that has penetrated into the pressure-sensitive adhesive layer can be efficiently dispersed, and whitening resistance and blister resistance are increased. Do.

Moreover, as for a copolymer (A), Preferably the structural unit derived from an alkoxyalkyl (meth)acrylate (a1) is 50-97 mass %, More preferably, it is 55-96 mass %, More preferably, it is 60-95 mass %. % have The amount of the structural unit can be determined from, for example, the amount of the monomer component introduced. The same applies to the amount of other structural units.

«Monomer (a2) containing a carboxyl group or an acid anhydride group»

Examples of the carboxyl group or acid anhydride group-containing monomer (a2) include carboxyl group-containing monomers such as (meth)acrylic acid, itaconic acid, crotonic acid, fumaric acid, and maleic acid; acid anhydride group-containing monomers such as phthalic anhydride and maleic anhydride; (meth)acrylic acid β-carboxyethyl, (meth)acrylic acid 5-carboxypentyl, succinic acid mono(meth)acryloyloxyethyl ester, ω-carboxypolycaprolactone mono(meth)acrylate containing carboxyl groups (meth)acryl rate can be mentioned.

The copolymer (A) may have a structural unit derived from the monomer (a2) containing one or more carboxyl groups or acid anhydride groups.

The amount of carboxyl group or acid anhydride group-containing monomer (a2) in all the monomer components used to obtain the copolymer (A) is 3 to 10 mass%, preferably 4 to 8 mass%, more preferably 5 to 8 mass% %am. Further, the copolymer (A) contains the structural unit derived from the monomer (a2) containing a carboxyl group or an acid anhydride group, preferably 3 to 10% by mass, more preferably 4 to 8% by mass, still more preferably 5 to 8% by mass % have

By using the copolymer (A) obtained by copolymerizing the monomer (a2) containing a carboxyl group or an acid anhydride group in the above amount, the wettability of the obtained pressure-sensitive adhesive layer to the adherend surface is reduced, and the adhesive force immediately after sticking is suppressed low. , the reworkability of the pressure-sensitive adhesive sheet tends to be improved.

By using the copolymer (A) obtained by copolymerizing the monomer (a2) containing a carboxyl group or an acid anhydride group in the above amount, the pressure-sensitive adhesive layer obtained after a certain period of time from sticking to the adherend increases the adhesive strength and tends to exhibit high adhesive strength There is this.

≪Other Monomers≫

The copolymer (A) may have a structural unit derived from another monomer other than the above-mentioned (a1) to (a2). Other monomers include, for example, alkyl (meth) acrylate, alicyclic hydrocarbon group or aromatic hydrocarbon group-containing (meth) acrylate, alkoxy polyalkylene glycol mono (meth) acrylate, styrenic monomer, hydroxyl group-containing monomer, amino group-containing A monomer, an amide group containing monomer, a nitrogen-type heterocyclic ring containing monomer, a cyano group containing monomer, vinyl acetate, and a polymerizable macromonomer are mentioned.

It is preferable that carbon number of the alkyl group in alkyl (meth)acrylate is 1-20. As alkyl (meth)acrylate, for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, iso-propyl (meth)acrylate, n-butyl (meth)acrylate , iso-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, Octyl (meth) acrylate, n-nonyl (meth) acrylate, iso-nonyl (meth) acrylate, n-decyl (meth) acrylate, iso-decyl (meth) acrylate, undeca (meth) acrylate , lauryl (meth) acrylate, oleyl (meth) acrylate, n-stearyl (meth) acrylate, and iso-stearyl (meth) acrylate.

As (meth)acrylate containing an alicyclic hydrocarbon group or an aromatic hydrocarbon group, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, and phenyl (meth)acrylate are mentioned, for example.

As alkoxy polyalkylene glycol mono(meth)acrylate, for example, methoxydiethylene glycol mono(meth)acrylate, methoxydipropylene glycol mono(meth)acrylate, ethoxytriethylene glycol mono(meth)acrylate, ethoxy Cydiethylene glycol mono(meth)acrylate and methoxytriethylene glycol mono(meth)acrylate are mentioned.

Examples of the styrene-based monomer include styrene; alkyl styrenes such as methyl styrene, dimethyl styrene, trimethyl styrene, propyl styrene, butyl styrene, hexyl styrene, heptyl styrene and octyl styrene; halogenated styrenes such as fluorostyrene, chlorostyrene, bromostyrene, and dibromostyrene; and functionalized styrene such as nitrostyrene, acetylstyrene and methoxystyrene.

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

Examples of the amino group-containing monomer include N,N-dialkylaminoalkyl (meth)acrylates such as N,N-dimethylaminoethyl (meth)acrylate and N,N-diethylaminoethyl (meth)acrylate. can

Examples of the amide group-containing monomer include (meth)acrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-propyl(meth)acrylamide, N-hexyl(meth)acrylamide, etc. of N-alkyl (meth)acrylamide; N,N-dialkyl (meth)acrylamide, such as N,N- dimethyl (meth)acrylamide and N,N- diethyl (meth)acrylamide, is mentioned.

Examples of the nitrogen-based heterocycle-containing monomer include N-vinylpyrrolidone, N-vinylcaprolactam, and (meth)acryloylmorpholine.

Examples of the cyano group-containing monomer include cyano (meth)acrylate, acrylonitrile, and methacrylonitrile.

Examples of the monomer of the polymer chain (main chain) portion constituting the polymerizable macromonomer include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate and tert -Alkyl (meth)acrylates, such as butyl (meth)acrylate, are mentioned, It is preferable that carbon number of the said alkyl group is 1-20, Moreover, it is (meth)acrylonitrile; Styrenic monomers, such as styrene and (alpha)-methylstyrene, are also mentioned.

The macromonomer is preferably a (meth)acrylic macromonomer, a (meth)acrylonitrile macromonomer and a styrene macromonomer.

Among other monomers, alkyl (meth)acrylate, (meth)acrylate containing an alicyclic hydrocarbon group or aromatic hydrocarbon group, and a styrenic monomer are preferable, and alkyl (meth)acrylate is more preferable.

The copolymer (A) may have a structural unit derived from one or two or more different monomers.

The amount of other monomers in all the monomer components used to obtain the copolymer (A) is preferably 47 mass % or less, more preferably 41 mass % or less, still more preferably 35 mass % or less. Further, in the copolymer (A), the amount of structural units derived from the other monomers is preferably 47 mass% or less, more preferably 41 mass% or less, still more preferably 35 mass% or less.

≪Physical properties and manufacturing method of (meth)acrylic copolymer (A)≫

The weight average molecular weight (Mw) of the copolymer (A) measured by the gel permeation chromatography (GPC) method is usually 200,000 to 2 million, preferably 400,000 to 1.5 million, more preferably 500,000 ~100 million. In such an aspect, there exists a tendency for the adhesive composition excellent in high temperature durability to be obtained.

The molecular weight distribution (Mw/Mn) which is ratio of Mw of a copolymer (A) and number average molecular weight (Mn) is 2-15 normally, Preferably it is 2.5-10, More preferably, it is 3-8. In such an aspect, there exists a tendency for the adhesive composition excellent in high temperature durability to be obtained.

Mw and Mw/Mn can be measured, for example, by the method described in Examples.

The glass transition temperature (Tg) of a copolymer (A) is -70 degreeC or more and less than 0 degreeC normally, Preferably it is -70-30 degreeC. In such an aspect, there exists a tendency for the adhesive composition which has the outstanding adhesive force at normal temperature to be obtained. The glass transition temperature can be calculated by the so-called Fox's formula. The same applies to the (meth)acrylic copolymer (B) described later.

Fox's equation: 1/Tg=(W ₁ /Tg ₁ )+(W ₂ /Tg ₂ )+… +(W _m /Tg _m )

W ₁ +W ₂ +… +W _m =1

In the above formula, Tg is the glass transition temperature (K) of the (meth)acrylic copolymer (A), Tg ₁ , Tg ₂ , ... , Tg _m is the glass transition temperature (K) of the homopolymer formed from each monomer, W ₁ , W ₂ , ... , W _m are the mass fractions of the structural units derived from each monomer in the copolymer (A). As a mass fraction of the structural unit derived from each monomer, the introduction ratio of each monomer with respect to all the monomers at the time of copolymer synthesis can be used.

In calculating Fox's formula, the glass transition temperature (Tg) of the homopolymer formed from each monomer can employ|adopt the value described in Polymer Handbook Fourth Edition (Wiley-Interscience 2003), for example.

A copolymer (A) can be manufactured by a well-known method, and it is preferable to manufacture by solution polymerization. Specifically, a monomer component and a polymerization solvent are introduced into a reaction vessel, a polymerization initiator is added, and the reaction temperature is heated to about 50 to 90° C., followed by reaction for 2 to 20 hours. For example, polymerization is performed in an inert gas atmosphere such as nitrogen gas. Moreover, you may further add a polymerization initiator, a chain transfer agent, a monomer component, and a polymerization solvent suitably during a polymerization reaction.

As a polymerization solvent, the organic solvent mentioned later is mentioned.

Examples of the polymerization initiator include organic polymerization initiators, and specific examples thereof include peroxides such as benzoyl peroxide and lauroyl peroxide, and azo compounds such as 2,2'-azobisisobutyronitrile. Among these, an azo compound is preferable. A polymerization initiator can use 1 type or 2 or more types.

The usage-amount of a polymerization initiator is 0.01-5 mass parts normally with respect to 100 mass parts of monomer components. In such an aspect, Mw of the copolymer (A) can be adjusted within an appropriate range.

<(meth)acrylic copolymer (B)>

The (meth)acrylic copolymer (B) is a copolymer of a monomer component containing 1 to 10% by mass of the amino group-containing monomer (b1), obtained by copolymerizing the monomer component, and has a glass transition temperature of 0° C. or higher.

The copolymer (B) is a copolymer other than the copolymer (A).

By adding the copolymer (B) to the copolymer (A) in a specific amount as a tackifying resin, an adhesive layer excellent in various properties such as blister resistance, whitening resistance, adhesive strength and reworkability can be easily formed.

≪Amino group-containing monomer (b1)≫

The amino group in the amino group-containing monomer (b1) includes, for example, a group represented by -NHR and a group represented by -NR ₂ other than the group represented by -NH ₂ . Here, R is, for example, an alkyl group.

As the amino group-containing monomer (b1), for example, N,N-dialkylaminoalkyl (meth)acryl such as N,N-dimethylaminoethyl (meth)acrylate and N,N-diethylaminoethyl (meth)acrylate rate can be mentioned. Preferably carbon number of the dialkylaminoalkyl group in N,N- dialkylaminoalkyl (meth)acrylate is 3-20, More preferably, it is 3-10.

The amount of the amino group-containing monomer (b1) in all the monomer components used to obtain the copolymer (B) is 1 to 10 mass%, preferably 3 to 10 mass%, more preferably 5 to 10 mass%. Further, the copolymer (B) preferably contains 1 to 10 mass % of the structural unit derived from the amino group-containing monomer (b1), more preferably 3 to 10 mass %, still more preferably 5 to 10 mass %.

By adding the copolymer (B) having a high (0° C. or higher) glass transition temperature obtained by copolymerizing the amino group-containing monomer (b1) in the above amount to the copolymer (A), an alkoxyalkyl as a main component of the copolymer (A) Blister resistance can be improved in the form of supplementing the fall of the cohesion force derived from the structural unit derived from (meth)acrylate (a1).

In addition, acid-base interaction between the carboxyl group or acid anhydride group derived from the carboxyl group or acid anhydride group-containing monomer (a2) in the copolymer (A) and the amino group derived from the amino group-containing monomer (b1) in the copolymer (B) By the action, compatibility between the copolymer (A) as the base polymer and the copolymer (B) having a high glass transition temperature is improved, and whitening resistance tends to be improved.

When the amount of the amino group-containing monomer (b1) in all the monomer components used in order to obtain a copolymer (B) exceeds 10 mass %, there exists a tendency for the whitening resistance of an adhesive layer to fall.

≪(meth)acrylic acid ester (b2)≫

It is preferable that the copolymer (B) further has a structural unit derived from (meth)acrylic acid ester (b2) (however, (meth)acrylic acid ester corresponding to the amino group-containing monomer (b1) is excluded).

Examples of the (meth)acrylic acid ester (b2) include alkyl (meth)acrylate, alicyclic hydrocarbon group or aromatic hydrocarbon group-containing (meth)acrylate, and alkoxypolyalkylene glycol mono(meth)acrylate. Specific examples thereof include the monomers described in the <<other monomers>> column in the (meth)acrylic copolymer (A).

Preferably the amount of (meth)acrylic acid ester (b2) in all the monomer components used in order to obtain a copolymer (B) is 50-99 mass %, More preferably, it is 60-97 mass %, More preferably, it is 70- 95 mass %. Further, the copolymer (B) preferably contains 50 to 99 mass% of the structural unit derived from (meth)acrylic acid ester (b2), more preferably 60 to 97 mass%, still more preferably 70 to 95 mass% .

≪Other Monomers≫

The copolymer (B) may further have a structural unit derived from another monomer other than the amino group-containing monomer (b1) and (meth)acrylic acid ester (b2) described above.

Examples of the other monomer include a styrene-based monomer, an amide group-containing monomer, a nitrogen-based heterocycle-containing monomer, a cyano group-containing monomer, and vinyl acetate. However, the monomer corresponding to (meth)acrylic acid ester (b2) is excluded.

≪Physical properties and manufacturing method of (meth)acrylic copolymer (B)≫

The weight average molecular weight (Mw) of a copolymer (B) measured by GPC method is 10,000-50,000 normally, Preferably it is 10,000-40,000, More preferably, it is 15,000-30,000. In such an aspect, it becomes difficult for a copolymer (B) to be unevenly distributed in an adhesive layer, and there exists a tendency for a favorable compatibility state to be acquired.

The molecular weight distribution (Mw/Mn) of the copolymer (B) is usually 2 to 15, preferably 2.5 to 10, more preferably 3 to 8. In such an aspect, there exists a tendency for a favorable commercial state to be obtained.

Mw and Mw/Mn can be measured, for example, by the method described in Examples.

The glass transition temperature (Tg) of a copolymer (B) is 0 degreeC or more, Preferably it is 50-200 degreeC, More preferably, it is 80-150 degreeC. In such an aspect, there exists a tendency for the adhesive composition excellent in blister resistance and adhesive force to be obtained. The glass transition temperature can be calculated by the so-called Fox's formula.

A copolymer (B) can use 1 type or 2 or more types.

The pressure-sensitive adhesive composition according to one embodiment of the present invention WHEREIN: Content of a copolymer (B) is 2-19 mass parts with respect to 100 mass parts of copolymers (A), Preferably it is 3-17 mass parts, More preferably It is usually 3 to 15 parts by mass. When the content of the copolymer (B) is equal to or greater than the lower limit, an adhesive layer excellent in blister resistance tends to be obtained, and when the content of the copolymer (B) is less than or equal to the upper limit, an adhesive layer excellent in adhesive strength tends to be obtained.

A copolymer (B) can be manufactured by a well-known method, and it is preferable to manufacture by solution polymerization. As specific manufacturing conditions, for example, the manufacturing conditions described in the column of copolymer (A) can be referred.

<Crosslinking agent (C)>

The crosslinking agent (C) is not particularly limited as long as it is a component capable of causing a crosslinking reaction with the copolymer (A). For example, an epoxy type crosslinking agent (C1), a metal chelate type crosslinking agent (C2), and an isocyanate type crosslinking agent (C3) are mentioned.

A crosslinking agent (C) can use 1 type or 2 or more types.

In the pressure-sensitive adhesive composition according to one embodiment of the present invention, the content of the crosslinking agent (C) is preferably 0.01 to 5 parts by mass, more preferably 0.01 to 5 parts by mass with respect to 100 parts by mass of the (meth)acrylic copolymer (A). It is 3 mass parts, More preferably, it is 0.01-1 mass part. In such an aspect, a crosslinked structure is sufficiently and appropriately formed, a cohesive force is high, and it is excellent in the balance of adhesive physical properties, and the adhesive composition excellent in durability can be obtained easily.

≪Epoxy-based crosslinking agent (C1)≫

Examples of the epoxy-based crosslinking agent (C1) include an epoxy compound in which the number of epoxy groups in one molecule is 2 or more, and specifically, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, Glycerin triglycidyl ether, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylylenediamine, N, N,N',N'-tetraglycidylaminophenylmethane, triglycidylisocyanurate, m-N,N-diglycidylaminophenylglycidyl ether, N,N-diglycidyltoluidine, N , N-diglycidyl aniline is mentioned. The number of epoxy groups in one molecule in the said epoxy compound is 2-10, for example.

The epoxy-based crosslinking agent (C1) may be used alone or in combination of two or more.

≪Metal chelate-based crosslinking agent (C2)≫

Examples of the metal chelate-based crosslinking agent (C2) include alkoxides, acetylacetone, ethyl acetoacetate, etc. to polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium. A compound in which the component of is coordinated is mentioned. Among these, an aluminum chelate compound is preferable. Specific examples include aluminum isopropylate, aluminum secondary butylate, aluminum ethylacetoacetate diisopropylate, aluminum trisethylacetoacetate, and aluminum trisacetylacetonate.

The metal chelate-based crosslinking agent (C2) may be used alone or in combination of two or more.

≪Isocyanate-based crosslinking agent (C3)≫

As an isocyanate-type crosslinking agent (C3), the isocyanate compound whose number of isocyanate groups in 1 molecule is 2 or more is mentioned, for example.

As a diisocyanate compound whose number of isocyanate groups in 1 molecule is 2, aliphatic diisocyanate, alicyclic diisocyanate, and aromatic diisocyanate are mentioned, for example. As an isocyanate compound whose number of isocyanate groups in 1 molecule is 3 or more, aromatic polyisocyanate, aliphatic polyisocyanate, and alicyclic polyisocyanate are mentioned, for example. Moreover, as an isocyanate compound, the number of isocyanate groups is 2 or 3 or more, for example, a multimer (for example, a dimer or a trimer, a biuret form, an isocyanurate body) of the said isocyanate compound, derivative (For example, polyhydric alcohol and two molecules addition reaction product with the above diisocyanate compound) and a polymer are mentioned.

The isocyanate-based crosslinking agent (C3) may be used alone or in combination of two or more.

<Additives>

The pressure-sensitive adhesive composition according to an embodiment of the present invention may include, for example, an antistatic agent, a silane coupling agent, a UV absorber, an antioxidant, a tackifying resin, a plasticizer, an antifoaming agent, a filler, You may contain at least 1 sort(s) chosen from a stabilizer, a softener, and a wettability regulator.

<Organic solvent>

The pressure-sensitive adhesive composition according to one embodiment of the present invention preferably contains an organic solvent.

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

The organic solvent can be used 1 type or 2 or more types.

The pressure-sensitive adhesive composition according to one embodiment of the present invention WHEREIN: The content rate of an organic solvent is 0-90 mass % normally, Preferably it is 10-80 mass %.

[Adhesive sheet]

The adhesive sheet which concerns on one Embodiment of this invention has the adhesive layer obtained from the adhesive composition mentioned above. An adhesive layer can be obtained by bridge|crosslinking the above-mentioned adhesive composition, specifically by bridge|crosslinking at least a (meth)acrylic-type copolymer (A) with a crosslinking agent (C).

The pressure-sensitive adhesive sheet includes, for example, a double-sided pressure-sensitive adhesive sheet having only the pressure-sensitive adhesive layer, a double-sided pressure-sensitive adhesive sheet having a base material and the pressure-sensitive adhesive layer formed on both surfaces of the base material, a single-sided pressure sensitive adhesive sheet having a base material and the pressure-sensitive adhesive layer formed on one side of the base material And the adhesive sheet by which the separator by which the peeling process was carried out was affixed to the surface which is not in contact with the other layer of the adhesive layer in these adhesive sheets is mentioned.

The formation conditions of an adhesive layer are as follows, for example. The composition is applied on a separator or a substrate and dried at usually 60 to 120° C., preferably 70 to 110° C., usually 1 to 10 minutes, preferably 2 to 5 minutes, to form a coating film . Then, when apply|coating to a separator, when bonding a base material or a separator to the coating film of the side without a separator, and apply|coating on a base material, a separator is bonded together on a coating film. Then, usually 1 day or more, preferably 2 to 10 days, usually 5 to 60°C, preferably 15 to 50°C, usually 30 to 70%RH, preferably 40 to 70% Curing (aging) in the RH environment. When crosslinking is performed under the aging conditions as described above, it is possible to efficiently form a crosslinked product (network polymer). In the case of the coating film clamped by the separator, one separator may be peeled off after aging, and a base material may be bonded together to the exposed adhesive layer.

As a base material and a separator, For example, plastic films, such as polyester (eg, polyethylene terephthalate), polyethylene, a polypropylene, ethylene-vinyl acetate copolymer; Non-woven; A paper separator is mentioned. The surface of the base material and the separator may be peeled off, respectively.

The thickness of an adhesive layer is 3-1000 micrometers normally, Preferably it is 5-500 micrometers. The thickness of the substrate and the separator is usually 10 to 1000 μm.

As a method of applying the pressure-sensitive adhesive composition, a known method, for example, a spin coat method, a knife coat method, a roll coat method, a bar coat method, a blade coat method, a die coat method, and a gravure coat method can be mentioned, and it is applied to a predetermined thickness. - An adhesive layer can be formed by drying.

The pressure-sensitive adhesive sheet according to one embodiment of the present invention has a pressure-sensitive adhesive layer having high heat-and-moisture resistance as described above. In particular, when the test is performed under an extremely high temperature and high humidity environment of 85°C/85%RH, the pressure-sensitive adhesive layer exhibits excellent blister resistance and whitening resistance. Moreover, while the adhesive sheet which concerns on one Embodiment of this invention is excellent in rework property, the adhesive force after lapse of a fixed period of time after sticking to a to-be-adhered body is high.

Therefore, the pressure-sensitive adhesive sheet according to one embodiment of the present invention can be used as an industrial pressure-sensitive adhesive sheet or for bonding applications of various resin films, and in particular, suitable for forming a pressure-sensitive adhesive layer contained in a product placed in a high-temperature, high-humidity environment. used

Examples of the adherend of the pressure-sensitive adhesive sheet according to one embodiment of the present invention include transparent resin films such as polycarbonate (PC), polyethylene terephthalate (PET), and polymethyl methacrylate (PMMA); Transparent plates, such as glass, are mentioned.

[Optical member]

The optical member which concerns on one Embodiment of this invention has the adhesive layer obtained from the adhesive composition mentioned above. As an optical member, the film which has the said adhesive layer as optical films, such as a polarizing film, retardation film, an elliptically polarizing film, an antireflection film, a brightness improving film, a light-diffusion film, and a hard-coat film, is mentioned, for example.

<Use of touch panel>

Although the adhesive sheet which concerns on one Embodiment of this invention can stick with respect to various members, it is suitable especially for sticking of the member for touch panels which bonds different types of members. A touch panel is mounted on in-vehicle devices, such as a car navigation device, in addition to a smart phone and tablet type computer, for example.

A touch panel includes a touch panel unit, and the touch panel unit includes, for example, a transparent member, a pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition according to an embodiment of the present invention, a transparent conductive film made of a metal or a metal oxide, or It has a transparent conductive film which consists of a metal with a support body, or a metal oxide with a support body.

Examples of the transparent member include transparent resin films such as polycarbonate (PC), polyethylene terephthalate (PET), and polymethyl methacrylate (PMMA); Transparent plates, such as glass, are mentioned.

Examples of the metal and metal oxide include indium tin oxide (ITO), antimony tin oxide (ATO), and tin oxide.

Examples of the touch panel unit include a resistive touch panel unit and an electrostatic capacitive touch panel unit, which are laminates of various materials, and are applied to bonding of the above various materials according to one embodiment of the present invention A pressure-sensitive adhesive composition may be used. As a use of the adhesive layer formed from the said adhesive composition, for example, the adhesive layer for bonding transparent members together, the adhesive layer for bonding a transparency member and a transparent conductive film, The adhesive layer for bonding a touch panel unit and a polarizing plate are mentioned. .

Since the touch panel unit is disposed on the outermost surface of the screen, high transparency is required for the pressure-sensitive adhesive layer used, and properties such as high moisture and heat resistance are required. The pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to one embodiment of the present invention has high heat-and-moisture resistance as described above. For this reason, this adhesive layer can be used suitably for a touchscreen unit.

(Example)

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to these Examples. In description of Examples etc. below, unless otherwise indicated, "part" represents "part by mass".

Each measured value was calculated|required with the following method.

[Glass Transition Temperature (Tg)]

The glass transition temperature (Tg) of the (meth)acrylic copolymer was calculated from the above formula of Fox.

[Weight average molecular weight (Mw) and molecular weight distribution (Mw/Mn)]

About the (meth)acrylic copolymer, the weight average molecular weight (Mw) and molecular weight distribution (Mw/Mn) by standard polystyrene conversion were calculated|required by the gel permeation chromatography (GPC) method under the following conditions.

・Measuring device: HLC-8120GPC (made by Tosoh)

・GPC column configuration: The following 5 columns (all made by Tosso)

(1)TSK-GEL HXL-H (guard column)

(2)TSK-GEL G7000HXL

(3)TSK-GEL GMHXL

(4)TSK-GEL GMHXL

(5)TSK-GEL G2500HXL

・Sample concentration: diluted with tetrahydrofuran to 1.0 mg/cm ³

· Mobile phase solvent: tetrahydrofuran

Flow rate: 1.0 cm ³ /min

·Column temperature: 40℃

[Polymerization Example 1]

92 parts of 2-methoxyethyl acrylate (MEA), 8 parts of acrylic acid (AA) and 200 parts of ethyl acetate were introduced into a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, and nitrogen gas was introduced at 75° C. was heated to Then, 0.1 part of 2,2'- azobisisobutyronitrile was added, and polymerization reaction was performed at 75-76 degreeC in nitrogen atmosphere for 4 hours. After completion of the reaction, the reaction solution was diluted with ethyl acetate to prepare a polymer solution having a solid content concentration of 39% by mass. Mw of the obtained (meth)acrylic copolymer (A1) was 700,000, and Mw/Mn was 7.5.

Except for changing the monomer composition as described in Table 1 (composition unit is parts by mass), polymerization was carried out in the same manner as in polymerization example 1, (meth)acrylic copolymers (A2) to (A3), (cA1) to ( cA3) was obtained.

[Polymerization Example 2]

In a reaction apparatus equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet tube, 90 parts of methyl methacrylate (MMA), 10 parts of N,N-dimethylaminoethyl methacrylate (DM), N-dodecylmer as a chain transfer agent 1 part of captan and 100 parts of ethyl acetate were introduce|transduced, and it heated up to 75 degreeC while introducing nitrogen gas. Then, 0.1 part of 2,2'- azobisisobutyronitrile was added, and polymerization reaction was performed at 75-76 degreeC in nitrogen atmosphere for 4 hours. After completion of the reaction, the reaction solution was diluted with ethyl acetate to prepare a polymer solution having a solid content concentration of 45% by mass. Mw of the obtained (meth)acrylic copolymer (B1) was 21000, and Mw/Mn was 4.5.

Polymerization was carried out in the same manner as in polymerization example 2, except that the monomer composition was changed as described in Table 2 (unit of composition is parts by mass), and (meth)acrylic copolymers (cB1) to (cB6) were obtained.

BA:n-butyl acrylate

MEA: 2-Methoxyethyl acrylate

HEA: 2-hydroxyethyl acrylate

AA: acrylic acid

MMA: Methyl methacrylate

DM:N,N-dimethylaminoethyl methacrylate

[Example 1]

To the polymer solution of the (meth)acrylic copolymer (A1) obtained in Polymerization Example 1, the polymer solution of the (meth)acrylic copolymer (B1) obtained in Polymerization Example 2 and the epoxy compound "E-AX" (tetrafunctional epoxy compound) ; The product made by Soken Chemicals, solid content 5%) was added, and the adhesive composition was obtained. Each compounding quantity is the quantity used as 10 parts of (meth)acrylic-type copolymer (B1) and 0.045 parts of solid content of epoxy-type compound "E-AX" with respect to 100 parts of (meth)acrylic-type copolymer (A1).

[Examples 2-5, Comparative Examples 1-12]

As shown in Table 3, except having changed the compounding composition, it carried out similarly to Example 1, and obtained the adhesive composition. In Table 3, the amount of each component is an amount (parts by mass) relative to 100 parts of the (meth)acrylic copolymer (A) or the comparative copolymer (cA1) to (cA3).

[Various evaluation tests]

The pressure-sensitive adhesive composition obtained in Examples and Comparative Examples was applied on a separator of medium peeling force so as to have a dry thickness of 50 μm, and dried at 90° C. for 4 minutes. After drying, it bonded together with the separator of light peeling power, and it was made to age|ripen at 40 degreeC for 3 days, and the sheet sample was produced.

In the following evaluation test, a polyethylene terephthalate (PET) film (Lumirer T60 100 μm thick PET, Tore) having a thickness of 100 μm was used as a substrate, and a polycarbonate (PC) plate (PC1600 2 mm thick, Tachiron) was used as an adherend. CI) and a glass plate (soda-lime glass 1 mm thick, manufactured by AGC Fabricec) were used.

<My Blister Castle>

After transferring the pressure-sensitive adhesive layer of the aged sheet sample to a PET film having a thickness of 100 μm, cut to a size of 60 mm × 50 mm, adhered to one side of a polycarbonate plate, and then in an autoclave adjusted to 50 ° C. and 5 atmospheres for 20 minutes was maintained and a trial version was prepared. Thereafter, the test plate was left to stand for 72 hours under the conditions of a temperature of 85° C. and a humidity of 85% RH, and the foaming/occurrence of float (blister) from the substrate was visually confirmed and evaluated according to the following criteria.

standard

AA: Appearance defects such as foaming/floating were not observed at all.

BB: Although slight appearance defects such as foaming/floating are observed, it is within a range without problems in practical use.

CC: Appearance defects such as foaming/floating were observed.

DD: Appearance defects such as foaming/floating were observed over a wide range.

<My Baekhwaseong>

After transferring the pressure-sensitive adhesive layer of the aged sheet sample to a PET film having a thickness of 100 μm, cut to a size of 60 mm × 50 mm, adhered to one side of a polycarbonate plate, and then in an autoclave adjusted to 50 ° C. and 5 atmospheres for 20 minutes It was made to hold|maintain, the test board was created, and the initial stage haze value was measured. Then, the said test board was left to stand for 72 hours under the conditions of a temperature of 85 degreeC and a humidity of 85 %RH, and the haze value after moist-heat treatment (durability) was measured with the haze meter.

standard

AA: The haze value after wet heat treatment (durability) was less than 1.5.

BB: The haze values after moist heat treatment (durability) were 1.5 or more and less than 2.0.

CC: The haze value after wet heat treatment (durability) was 2.0 or more.

<Rework Castle>

After the pressure-sensitive adhesive layer of the aged sheet sample was transferred to a PET film having a thickness of 100 μm, it was cut to a size of 25 mm × 100 mm, affixed to one side of a polycarbonate plate, and pressed with a 2 kg roller in 3 reciprocations. After leaving to stand for 20 minutes, the PET film was peeled off at a peel angle of 180 degrees and a tensile rate of 300 mm/min, and the initial adhesive force was measured.

standard

AA: Initial adhesive force was less than 0.5N/25mm.

BB: Initial adhesive force was 0.5 N/25 mm or more and less than 1.0 N/25 mm.

CC: Initial adhesive force was 1.0N/25mm or more.

<Adhesiveness>

After transferring the pressure-sensitive adhesive layer of the aged sheet sample to a PET film having a thickness of 100 μm, it is cut to a size of 25 mm × 100 mm, adhered to one side of a polycarbonate plate or a glass plate, and then in an autoclave adjusted to 50 ° C., 5 atm. After holding for 20 minutes and leaving it to stand for 60 minutes in a room temperature environment, the PET film was peeled off at a peeling angle of 180 degrees and a tensile rate of 300 mm/min, and the adhesive force was measured.

standard

AA: The adhesive force was 20N/25mm or more.

BB: The adhesive force was 10N/25mm or more and less than 20N/25mm.

CC: The adhesive force was less than 10N/25mm. Or ZIPPING (Stick-Slip phenomenon) occurred.

Y-75: isocyanate-based compound (isocyanate-based crosslinking agent; Soken Chemical Co., Ltd., isocyanurate of hexamethylene diisocyanate: solid content 75%, ethyl acetate solution)

E-AX: Epoxy compound (epoxy crosslinking agent; Soken Chemical Co., Ltd., tetrafunctional epoxy compound: solid content 5%, toluene/isopropyl alcohol solution)

The amount of the crosslinking agent in Table 3 is the solid content.

From the comparison between Examples 1 and 2 and Comparative Example 1, by using the copolymer (A) containing a specific amount of a structural unit derived from an alkoxyalkyl (meth)acrylate (a1), whitening resistance and rework resistance improvement can be seen.

From the comparison of Examples 1, 3 and Comparative Example 2, by using a copolymer (A) containing a specific amount of a structural unit derived from a monomer (a2) containing a carboxyl group or an acid anhydride group, blister resistance, rework resistance and It can be seen that the adhesive strength is improved.

From the comparison between Example 1 and Comparative Example 3, by using a copolymer (A) containing a structural unit derived from a carboxyl group or acid anhydride group-containing monomer (a2), a public containing a structural unit derived from a hydroxyl group-containing monomer It can be seen that the reworkability and adhesive force are improved with respect to the coalescence.

From the comparison between Example 1 and Comparative Examples 4 to 6, by using the copolymer (B) containing a specific amount of a structural unit derived from the amino group-containing monomer (b1) in combination with the copolymer (A), blister resistance and bag resistance It can be seen that Mars is improving.

From the comparison of Example 1 and Comparative Example 7, it can be seen that by using the copolymer (B) and the copolymer (A) having a glass transition temperature of 0°C or higher together, the blister resistance and adhesive force are improved.

From the comparison of Examples 4-5 and Comparative Examples 8-10, it can be seen that the blister resistance and adhesive force are improved by using a specific amount of the copolymer (B) with respect to the copolymer (A).

From the comparison between Example 1 and Comparative Examples 11 to 12, it was found that the blister resistance and whitening resistance were improved by using the copolymer (B) containing a specific amount of the structural unit derived from the amino group-containing monomer (b1). can

Claims (5)

A (meth)acrylic copolymer (A) which is a copolymer of a monomer component containing 50 to 97% by mass of an alkoxyalkyl (meth)acrylate (a1) and 3 to 10% by mass of a carboxyl or acid anhydride group-containing monomer (a2) and ,
A (meth)acrylic copolymer (B) which is a copolymer of a monomer component containing 1 to 10% by mass of an amino group-containing monomer (b1), and has a glass transition temperature of 0° C. or higher;
Crosslinking agent (C)
It is a pressure-sensitive adhesive composition containing,
The adhesive composition containing 2-19 mass parts of said (meth)acrylic-type copolymers (B) with respect to 100 mass parts of said (meth)acrylic-type copolymers (A). The pressure-sensitive adhesive composition according to claim 1, wherein the (meth)acrylic copolymer (B) has a weight average molecular weight of 10,000 to 50,000. The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the crosslinking agent (C) is an epoxy-based crosslinking agent (C1). The adhesive sheet which has an adhesive layer obtained from the adhesive composition in any one of Claims 1-3. The optical member which has an adhesive layer obtained from the adhesive composition in any one of Claims 1-3.