KR102087736B1 - Adhesive composition, adhesive layer, adhesive sheet and laminate for touch panel - Google Patents

Abstract

Provided is a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer excellent in step followingability and durability that can be traced to a adherend having a low dielectric constant and a step without generating bubbles or the like at the time of sticking.
(A) (meth) acrylic-type copolymer and (B) crosslinking agent containing a crosslinking agent, The said copolymer (A) is alkyl methacryl whose carbon number of (a1) alkyl group is 10 or more with respect to 100 mass% of all monomer components. 20 to 39 mass% of rate, 30 to 60 mass% of alkyl acrylate having 8 or more carbon atoms of (a2) alkyl group, 1 to 20 mass% of (a3) hydroxyl group-containing monomer, and (a4) nitrogen atom-containing monomer 0 to 5 It is a copolymer obtained by copolymerizing the monomer component containing mass%, The adhesive composition characterized by the above-mentioned.

Description

Adhesive composition, adhesive layer, adhesive sheet, and laminated body for touch panels {ADHESIVE COMPOSITION, ADHESIVE LAYER, ADHESIVE SHEET AND LAMINATE FOR TOUCH PANEL}

The present invention relates to a pressure-sensitive adhesive composition excellent in low dielectric constant, step tracking and durability, a pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer, and a touch panel laminate having the pressure-sensitive adhesive layer.

Recently, image display devices such as liquid crystal display devices, and input devices such as touch panels used in combination with image display devices have become widely used. In the manufacture of these image display apparatuses and input apparatuses, the adhesive sheet which has an adhesive layer is used when bonding each structural member.

As the performance required for the adhesive sheet for touch panels, for example, low dielectric constant for preventing malfunction in touch panel operation, step absorption for not generating voids when bonding to a member having a step, and heat resistance and heat and moisture resistance And high durability such as wet heat whitening resistance.

For example, in a liquid crystal display device, front transparent plates, such as a glass plate, are provided in the visual recognition side rather than a display panel through an adhesive layer. On the other hand, in order to display a specific liquid smoke or a figure in the periphery of a screen and to improve designability, a printing layer may be formed in the peripheral edge part of a front transparent board. For example, in a touch panel, transparent plates, such as a glass plate, and the transparent conductive film in which transparent conductive thin films, such as indium tin oxide (ITO), were formed on the surface are laminated | stacked through an adhesive layer.

As described above, in the liquid crystal display device, the touch panel, and the like, a configuration including a member having a step based on a printed layer, a conductive thin film, or the like has been increasing. For this reason, the adhesive step layer used for affixing and fixing the said member requires the outstanding step | following followability so that a space | gap does not generate | occur | produce.

For example, in Patent Documents 1 and 2, a pressure-sensitive adhesive containing a (meth) acrylic polymer obtained by polymerizing a monomer component containing a specific alkyl (meth) acrylate, with the object of realizing a pressure-sensitive adhesive layer having a low dielectric constant, Is disclosed.

In addition, Patent Document 3 discloses an adhesive sheet having a pressure-sensitive adhesive layer containing an acrylic polymer obtained by polymerizing a specific monomer component, with an object of providing a pressure-sensitive adhesive sheet excellent in moisture-proof turbidity and excellent in step absorption. It is.

However, in view of providing a pressure-sensitive adhesive layer excellent in balance of low dielectric constant, step absorption and durability, further improvement in performance is desired for the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer.

Japanese Laid-Open Patent Publication 2012-246477 Japanese Unexamined Patent Publication No. 2013-194170 Japanese Unexamined Patent Publication No. 2013-122035

An object of the present invention is to provide a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer excellent in step tracking and durability that can be traced to a adherend having a low dielectric constant and a step without generating bubbles or the like at the time of sticking. .

The present inventors earnestly examined in order to solve the said subject. As a result, it discovered that the said subject can be solved by using the adhesive composition which has the following specific structure, and came to complete this invention.

This invention is the following [1]-[10], for example.

[1] A pressure-sensitive adhesive composition containing the (A) (meth) acrylic copolymer and the (B) crosslinking agent, wherein the copolymer (A) has 10 or more carbon atoms of (a1) alkyl group to 100 mass% of all monomer components. 20 to 39 mass% of alkyl methacrylate, 30 to 60 mass% of alkyl acrylates having 8 or more carbon atoms of the (a2) alkyl group, 1 to 20 mass% of (a3) hydroxyl group-containing monomers, and (a4) nitrogen atom-containing monomers It is a copolymer obtained by copolymerizing the monomer component containing 0-5 mass%, The adhesive composition characterized by the above-mentioned.

[2] The monomer component forming the copolymer (A), wherein the alkyl groups included in the alkyl methacrylate (a1) and the alkyl acrylate (a2) are all linear alkyl groups or all are branched alkyl groups. The adhesive composition as described in 1].

[3] The pressure-sensitive adhesive composition according to the above [1] or [2], wherein in the monomer component forming the copolymer (A), the hydroxyl group-containing monomer (a3) is a hydroxyl group-containing (meth) acrylate.

[4] The pressure-sensitive adhesive composition according to any one of the above [1] to [3], wherein the amount of the acid group-containing monomer (a6) is 0.1% by mass or less with respect to 100% by mass of all the monomer components forming the copolymer (A). .

[5] The pressure-sensitive adhesive composition according to any one of [1] to [4], wherein the weight average molecular weight (Mw) measured by the gel permeation chromatography method of the copolymer (A) is 30000 to 500000 in terms of polystyrene. .

[6] The pressure-sensitive adhesive composition according to any one of the above [1] to [5], further comprising (C) a silane coupling agent.

[7] The pressure-sensitive adhesive composition according to any one of [1] to [6], wherein a gel fraction of the pressure-sensitive adhesive formed from the pressure-sensitive adhesive composition is 10 to 60 mass%.

[8] An adhesive layer formed from the pressure-sensitive adhesive composition according to any one of [1] to [7].

[9] An adhesive sheet having an adhesive layer according to the above [8].

[10] A touch panel laminate comprising a support, a pressure-sensitive adhesive layer according to the above [8], and a substrate with a conductive thin film formed of a metal or metal oxide on a substrate surface in this order.

ADVANTAGE OF THE INVENTION According to this invention, the adhesive composition which can form the adhesive layer excellent in the level | step difference followable | trackability and durability which can follow the adherend which has low dielectric constant and a step | step without generating a bubble etc. at the time of sticking can be provided. .

Hereinafter, the adhesive composition, the adhesive layer, the adhesive sheet, and the laminated body of this invention are demonstrated.

[Adhesive Composition]

The adhesive composition of this invention is an adhesive composition containing the (meth) acrylic-type copolymer (A) and crosslinking agent (B) demonstrated below. Moreover, the said composition may further contain at least 1 sort (s) chosen from a silane coupling agent (C) and an organic solvent (D).

[(Meth) acrylic copolymer (A)]

(Meth) acrylic-type copolymer (A) with respect to 100 mass% of all monomer components,

(a1) 20-39 mass% of alkyl methacrylates whose carbon number of an alkyl group is ten or more,

(a2) 30-60 mass% of alkylacrylates whose carbon number of an alkyl group is 8 or more,

(a3) 1-20 mass% of hydroxyl-containing monomers,

(a4) 0-5 mass% of nitrogen atom containing monomers

It is a copolymer obtained by copolymerizing the monomer component containing.

By using the copolymer obtained by copolymerizing the said monomer component in the said range, the adhesive layer excellent in the balance of low dielectric constant, step | following trackability, and durability can be formed.

In this specification, acryl and methacryl are named generically also as "(meth) acryl." Moreover, the structural unit derived from the certain monomer a contained in a polymer is also described as "monomer a unit." Moreover, said (a1)-(a4) are also described as "monomer (a1)"-"monomer (a4)", respectively.

Hereinafter, it describes about a monomer component.

<< alkyl methacrylate (a1) >>

Alkyl methacrylate (a1) is an alkyl methacrylate whose carbon number of an alkyl group is ten or more. Specifically, CH ₂ = C (CH ₃ ) -COOR ¹ is preferable. In formula, R <^1> is a C10 or more linear or branched alkyl group. Carbon number of the said alkyl group becomes like this. Preferably it is 10-20, More preferably, it is 10-18.

When the (meth) acrylic copolymer containing the alkyl methacrylate unit which has such a long chain alkyl group is used, the adhesive layer with little orientation polarization can be obtained. For example, there exists a tendency for the adhesive layer with a low dielectric constant to be obtained by using said (a1).

Examples of the alkyl methacrylate having 10 or more carbon atoms in the alkyl group include linear alkyl methacrylates such as decyl methacrylate, undemethacrylate, lauryl methacrylate and stearyl methacrylate; And branched alkyl methacrylates such as isodecyl methacrylate and isostearyl methacrylate. These may be used individually by 1 type and may use 2 or more types.

The usage-amount of an alkyl methacrylate (a1) is 20-39 mass% in 100 mass% of monomer components, Preferably it is 25-39 mass%, More preferably, it is 30-39 mass%. When the usage-amount of an alkyl methacrylate (a1) exceeds the said 39 mass%, the problem that the level | step difference followable | trackability of an adhesive layer falls, and suitable adhesive performance may not be obtained may arise. When the usage-amount of alkyl methacrylate (a1) is less than said 20 mass%, problems, such as durability of an adhesive layer fall and low dielectric constant deteriorate, may arise.

<< alkyl acrylate (a2) >>

Alkyl acrylate (a2) is alkyl acrylate whose carbon number of an alkyl group is eight or more. Specifically, CH ₂ = CH-COOR ² is preferable. In formula, R <^2> is a C8 or more linear or branched alkyl group. Preferably carbon number of the said alkyl group is 8-18, More preferably, it is 8-12.

By using the (meth) acrylic copolymer containing the alkyl acrylate unit which has such a long chain alkyl group, affinity with respect to a to-be-adhered body can be improved, suppressing the raise of the dielectric constant of an adhesive layer. For example, there exists a tendency for the adhesive layer with a low dielectric constant to be obtained by using said (a2).

Examples of the alkyl acrylate having 8 or more carbon atoms in the alkyl group include linear alkyl acrylates such as octyl acrylate, nonyl acrylate, decyl acrylate, undeca acrylate, lauryl acrylate and stearyl acrylate; And branched alkyl acrylates such as 2-ethylhexyl acrylate, isooctyl acrylate, isononyl acrylate, isodecyl acrylate and isostearyl acrylate. These may be used individually by 1 type and may use 2 or more types.

The usage-amount of an alkyl acrylate (a2) is 30-60 mass% in 100 mass% of monomer components, Preferably it is 35-60 mass%, More preferably, it is 40-60 mass%. When the usage-amount of alkyl acrylate (a2) exceeds 60 mass%, problems, such as durability of an adhesive layer fall and low dielectric constant deteriorate, may arise. When the usage-amount of an alkyl acrylate (a2) is less than 30 mass%, problems, such as the level | step difference followability of an adhesive layer, may fall.

In the monomer component which forms copolymer (A), it is preferable that the said alkyl groups which alkyl methacrylate (a1) and alkyl acrylate (a2) have are all linear alkyl groups, or all are branched alkyl groups.

That is, it is preferable to use the said (a1) and (a2) which are all linear, or to use the said (a1) and (a2) which are all branched. In the former case, there exists a tendency for the adhesive layer which is low dielectric constant, and which is more excellent in affinity to a to-be-adhered body, and a level | step difference followable | trackability to be obtained. In the latter case, a pressure-sensitive adhesive layer having a low dielectric constant and more excellent durability tends to be obtained. In particular, it is preferable to use the above-mentioned (a1) and (a2) in which all alkyl groups are branched from the point which can suppress wet heat whitening more.

<< hydroxyl-containing monomer (a3) >>

As a hydroxyl-containing monomer (a3), a hydroxyl-containing (meth) acrylate is mentioned, for example, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxy specifically, And hydroxyalkyl (meth) acrylates such as oxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate and 8-hydroxyoctyl (meth) acrylate. Carbon number of the hydroxyalkyl group in hydroxyalkyl (meth) acrylate is 2-8 normally, Preferably it is 2-6.

As the hydroxyl group-containing monomer (a3), hydroxyl group-containing acrylates such as hydroxyalkyl acrylates are preferable when all of the alkyl groups are linear (a1) and (a2) from the viewpoint of wet heat whitening resistance of the pressure-sensitive adhesive layer. In addition, when using the said (a1) and (a2) whose alkyl groups are all branched, hydroxyl group containing methacrylates, such as hydroxyalkyl methacrylate, are preferable.

The usage-amount of a hydroxyl-containing monomer (a3) is 1-20 mass% in 100 mass% of monomer components, Preferably it is 2-15 mass%. Especially when all the alkyl groups of monomer (a1) and (a2) are branched chains, Preferably it is 1-10 mass%, More preferably, it is 2-5 mass%, The alkyl groups of monomer (a1) and (a2) When all are linear, Preferably it is 2-20 mass%, More preferably, it is 5-15 mass%. When the usage-amount of monomer (a3) exceeds 20 mass%, the problem that the low dielectric constant of an adhesive layer deteriorates, and a step | following traceability may fall. When the amount of the monomer (a3) used is less than 1% by mass, the crosslinked structure is not effectively formed, and a pressure-sensitive adhesive layer having an appropriate cohesive force cannot be obtained, which may cause problems such as deterioration in durability or whitening after moist heat.

<< nitrogen atom containing monomer (a4) >>

As a nitrogen atom containing monomer (a4), an amino group containing monomer, an amide group containing monomer, a nitrogen-type heterocycle containing monomer, and a cyano group containing monomer are mentioned, for example. Monomers containing both a hydroxyl group and a nitrogen atom are classified as monomers (a4).

Among these, an amino group containing monomer and an amide group containing monomer are preferable. In particular, when using the above-mentioned (a1) and (a2) in which all alkyl groups are linear from a viewpoint of wet heat whitening resistance of an adhesive layer, an amino-group containing monomer is preferable, The said alkyl groups are all branched (a1) and ( When using a2), an amide group containing monomer is preferable.

As an amino group containing monomer, an amino group containing (meth) acrylate is mentioned, for example. Specifically, CH ₂ = C (R ³ ) -COO-R ⁴ -NR ⁵ ₂ is preferable. In formula, R <^3> is a hydrogen atom or a methyl group, R <^4> is a C1-C5, Preferably it is an alkylene group of 1-3, R <^5> is a hydrogen atom or a C1-C2 alkyl group each independently. As a specific example, dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate are mentioned.

As the amide group-containing monomer Specifically, ^{_{CH 2 = C (R 6)}} -CO-NR 7 2 are preferred. In formula, R <^6> is a hydrogen atom or a methyl group, R <^7> is a hydrogen atom or a C1-C6 alkyl group each independently. Specific examples include (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, and N-hexyl (meth) acrylamide.

Examples of the nitrogen-based heterocycle-containing monomers include vinylpyrrolidone, acryloyl morpholine, and vinyl caprolactam. As a cyano group containing monomer, a cyano (meth) acrylate and a (meth) acrylonitrile are mentioned, for example.

However, it is preferable to use the nitrogen atom containing monomer (a4) which does not have a cyclic structure in the copolymer (A) in this invention.

The usage-amount of a nitrogen atom containing monomer (a4) is 0-5 mass% in 100 mass% of monomer components, Preferably it is 0.5-4 mass%, More preferably, it is 1-3 mass%. When the usage-amount of a nitrogen atom containing monomer (a4) exceeds 5 mass%, problems, such as the fall of the wet heat whitening resistance of an adhesive layer, may arise. When the usage-amount of a nitrogen atom containing monomer (a4) is more than the said lower limit, the crosslinking reactivity of a copolymer (A) and a crosslinking agent (B) improves, and there exists a tendency for the adhesive layer with high cohesion force to be obtained.

<< other monomer (a5) >>

Alkyl methacrylate (a5-1) having 1 to 9 carbon atoms of an alkyl group as a monomer component forming a (meth) acrylic copolymer (A); CH ₂ = C (CH ₃ ) -COOR ⁸ ; R ⁸ is carbon 1 Or an alkyl group having 1 to 7 carbon atoms (a5-2) (CH ₂ = CH-COOR ⁹ ; R ⁹ is an alkyl group having 1 to 7 carbon atoms). .

However, the sum total of the usage-amount of alkyl methacrylate (a5-1) and alkyl acrylate (a5-2) is 30 in 100 mass% of monomer components which form a (meth) acrylic-type copolymer (A) from a low dielectric constant viewpoint. Mass% or less is preferable, More preferably, it is 20 mass% or less, More preferably, it is 15 mass% or less.

As alkyl methacrylate (a5-1) and alkyl acrylate (a5-2), for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) Acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate Can be mentioned. These may be used individually by 1 type and may use 2 or more types.

As a monomer component which forms a (meth) acrylic-type copolymer (A), an alicyclic group or an aromatic ring containing (meth) acrylate and an alkoxyalkyl is provided in the range which does not impair the physical property of a (meth) acrylic-type copolymer (A). Other (meth) acrylic acid ester (a5-3), such as (meth) acrylate and an alkoxy polyalkylene glycol mono (meth) acrylate, can also be used.

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

As an alkoxyalkyl (meth) acrylate, for example, methoxymethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 3-methoxypropyl (meth) Acrylate, 3-ethoxy propyl (meth) acrylate, 4-methoxy butyl (meth) acrylate, and 4-ethoxy butyl (meth) acrylate are mentioned.

As alkoxy polyalkylene glycol mono (meth) acrylate, For example, methoxy diethylene glycol mono (meth) acrylate, methoxy dipropylene glycol mono (meth) acrylate, ethoxy triethylene glycol Colmono (meth) acrylate, an ethoxy diethylene glycol mono (meth) acrylate, and a methoxy triethylene glycol mono (meth) acrylate are mentioned.

Moreover, in the range which does not impair the physical property of a (meth) acryl-type copolymer (A), for example, styrene, methyl styrene, dimethyl styrene, trimethyl styrene, propyl styrene, butyl styrene, hexyl styrene Styrene system, such as alkyl styrene, fluoro styrene, chloro styrene, bromo styrene, dibromos styrene, iodide styrene, acetyl styrene, and methoxy styrene, such as styrene, heptyl styrene, and octyl styrene Monomers; Copolymerizable monomers (a5-4), such as vinyl acetate, can also be used.

It is preferable that all the usage-amount of another monomer (a5) is 0-40 mass% in 100 mass% of monomer components, More preferably, it is 0-25 mass%. However, since there exists a tendency to raise a dielectric constant, it is preferable not to use an alkoxy alkyl (meth) acrylate and an alkoxy polyalkylene glycol mono (meth) acrylate as much as possible.

Another monomer (a5) may be used individually by 1 type, and 2 or more types may be used.

<< acidic radical containing monomer (a6) >>

As an acidic radical in this specification, a carboxyl group, an acid anhydride group, a phosphoric acid group, and a sulfuric acid group are mentioned, for example. Examples of the carboxyl group-containing monomer include (meth) acrylic acid β-carboxyethyl, (meth) acrylic acid 5-carboxypentyl, succinic acid mono (meth) acryloyloxyethyl ester, and ω-carboxypolycaprolactone mono (meth) acrylate. Carboxyl group containing (meth) acrylates, such as these; Acrylic acid, methacrylic acid, itaconic acid, crotonic acid, fumaric acid, and maleic acid are mentioned. As an acid anhydride group containing monomer, maleic anhydride and itaconic anhydride are mentioned, for example. As a phosphate group containing monomer, the (meth) acrylic-type monomer which has a phosphoric acid group in a side chain is mentioned, As a sulfuric acid group containing monomer, the (meth) acrylic-type monomer which has a sulfate group in a side chain is mentioned.

It is preferable that all the usage-amount of an acidic radical containing monomer is 0.1 mass% or less in 100 mass% of monomer components, More preferably, it is 0 mass%. When the total amount of the acid group-containing monomer is in the above range, the (meth) acrylic copolymer (A) does not corrode even if it comes into direct contact with an electrode and a wiring pattern made of a metal or a metal oxide. For this reason, the adhesive composition of this invention can be used suitably for a touch panel use, for example. For example, the acid value of the (meth) acrylic copolymer (A) is preferably 0.5 mgKOH / g or less, and more preferably 0.1 mgKOH / g or less.

<< production conditions of (meth) acrylic copolymer (A) >>

Although the manufacturing conditions of a (meth) acrylic-type copolymer (A) are not specifically limited, For example, it can manufacture by solution polymerization method. Specifically, a polymerization solvent and a monomer component are introduced into the reaction vessel, a polymerization initiator is added under an inert gas atmosphere such as nitrogen gas, and the reaction start temperature is usually set to 40 to 100 ° C, preferably 50 to 80 ° C, Usually, the reaction system is maintained at a temperature of 50 to 90 ° C, preferably 70 to 90 ° C, and reacted for 4 to 20 hours.

Although copolymer (A) is obtained by copolymerizing the monomer component mentioned above, for example, a random copolymer may be sufficient and a block copolymer may be sufficient. In these, a random copolymer is preferable.

As a polymerization solvent used for solution polymerization, For example, aromatic hydrocarbons, such as benzene, toluene, xylene; aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane, n-octane; Alicyclic hydrocarbons such as cyclopentane, cyclohexane, cycloheptane and cyclooctane; Ethers such as diethyl ether, diisopropyl ether, 1,2-dimethoxy ether, dibutyl ether, tetrahydrofuran, dioxane, anisole, phenylethyl ether and diphenyl ether; Halogenated hydrocarbons such as chloroform, carbon tetrachloride, 1,2-dichloroethane 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. These polymerization solvents may be used individually by 1 type, and 2 or more types may be used.

As a polymerization initiator used for solution polymerization, an azo initiator and a peroxide initiator are mentioned, for example. Specifically, azo compounds, such as 2,2'- azobisisobutyronitrile, and peroxides, such as benzoyl peroxide and lauroyl peroxide, are mentioned. Among these, an azo compound is preferable. Examples of the azo compound include 2,2'-azobisisobutyronitrile, 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile) and 2,2'-azo. Bis (2-cyclopropylpropionitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylbutyronitrile), 1, 1'-azobis (cyclohexane-1-carbonitrile), 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'-azobis (isobutylamide) dihydrate, 4,4'-azobis (4-cyanopentanoic acid), 2,2 '-Azobis (2-cyanopropanol), dimethyl-2,2'-azobis (2-methylpropionate), 2,2'-azobis [2-meth -N- (2- hydroxyethyl) propionamide may be mentioned. These polymerization initiators may be used individually by 1 type, and may use 2 or more types.

The polymerization initiator is usually used in an amount within the range of 0.01 to 5 parts by mass, preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the monomer component forming the (meth) acrylic copolymer (A). Moreover, you may add a polymerization initiator, a chain transfer agent, a monomer component, and a polymerization solvent suitably during the said polymerization reaction.

<< Physical properties and content of the (meth) acrylic copolymer (A) >>

The weight average molecular weight (Mw) measured by the gel permeation chromatography (GPC) method of a (meth) acrylic-type copolymer (A) is 30000-500000 in polystyrene conversion value normally, Preferably it is 50000-400000, More preferably Is 200000 to 390000. By using the copolymer (A) in which Mw exists in the said range and having the said monomeric unit, it is easy to balance adhesive force, it can be set as the adhesive composition of the viscosity suitable for coating, and the adhesive layer excellent in the step | following followability is obtained. There is a tendency.

When the molecular weight distribution (Mw / Mn) measured by GPC method of a (meth) acrylic-type copolymer (A) is 3-30 normally, when the alkyl groups of monomer (a1) and (a2) are all branched, Preferably it is 5-25, More preferably, it is 8-20, When all the alkyl groups of a monomer (a1) and (a2) are linear, Preferably it is 4-20, More preferably, it is 5-10.

The glass transition temperature (Tg) of a (meth) acrylic-type copolymer (A) can be computed by the formula of Fox from the monomer unit which comprises the said copolymer, and its content rate, for example. For example, the (meth) acrylic copolymer (A) can be synthesized so that the glass transition temperature (Tg) determined by the formula of Fox is usually -70 to 0 ° C, preferably -60 to -20 ° C. . By using the (meth) acrylic-type copolymer (A) which has such a glass transition temperature (Tg), the adhesive composition excellent in adhesiveness can be obtained at normal temperature.

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 formula, Tg is the glass transition temperature of the (meth) acrylic copolymer (A), and Tg ₁ , Tg ₂ ,. , Tg _m is the glass transition temperature of the homopolymer consisting of each monomer, and W ₁ , W ₂ ,. , W _m is a weight fraction in the copolymer (A) of the structural unit derived from each monomer.

As a glass transition temperature of the homopolymer which consists of each monomer in the said Formula of Fox, the value described, for example in Polymer Handbook Forth Edition (Wiley-Interscience 1999) can be used.

Content of the (meth) acrylic copolymer (A) in the adhesive composition of this invention is 60-99.99 mass% normally in 100 mass% of solid content except the organic solvent in a composition, More preferably, 70-99.95 mass%, Especially preferably, Is 80-99.90 mass%. When content of a (meth) acrylic-type copolymer (A) exists in the said range, the balance of the performance as an adhesive can be taken and it is excellent in adhesive characteristic.

[Bridge] (B)

The crosslinking agent (B) is not particularly limited as long as it is a component capable of causing a crosslinking reaction with the (meth) acrylic copolymer (A). For example, an isocyanate compound (B1), a metal chelate compound (B2), and an epoxy compound (B3) are mentioned.

A crosslinking agent (B) may be used individually by 1 type, and may use 2 or more types.

In the adhesive composition of the present invention, the total content of the crosslinking agent (B) is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 2.5 parts by mass, based on 100 parts by mass of the (meth) acrylic copolymer (A), More preferably, it is 0.1-1 mass part. Thus, by containing a fixed amount of crosslinking agent (B), an appropriate crosslinking degree can be achieved and durability in the outstanding adhesiveness, dimensional stability, and high humidity heat environment can be implement | achieved.

<< isocyanate compound (B1) >>

As the isocyanate compound (B1), an isocyanate compound having two or more isocyanate groups in one molecule is usually used. A crosslinked body (network polymer) can be formed by crosslinking a (meth) acrylic copolymer (A) with an isocyanate compound (B1).

The number of isocyanate groups of an isocyanate compound (B1) is 2 or more normally, Preferably it is 2-8, More preferably, it is 3-6. If the number of isocyanate groups exists in the said range, it is preferable at the point of the crosslinking reaction efficiency of a (meth) acrylic-type copolymer (A) and an isocyanate compound (B1), and the flexibility of an adhesive layer.

Examples of the diisocyanate compound having 2 isocyanate groups in one molecule include aliphatic diisocyanate, alicyclic diisocyanate, and aromatic diisocyanate. As aliphatic diisocyanate, ethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2-methyl-1,5-pentane isocyanate C4-C30 aliphatic diisocyanates, such as cyanate, 3-methyl- 1, 5- pentane diisocyanate, and 2, 2, 4- trimethyl- 1, 6- hexamethylene diisocyanate Cyanate. As alicyclic diisocyanate, isophorone diisocyanate, cyclopentyl diisocyanate, cyclohexyl diisocyanate, hydrogenated xylylenediisocyanate, hydrogenated tolylene diisocyanate C7-C30 alicyclic diisocyanate, such as a nate, a hydrogenated diphenyl methane diisocyanate, and a hydrogenated tetramethyl xylylene diisocyanate, is mentioned. As aromatic diisocyanate, for example, phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, naphthylene diisocyanate, diphenyl ether diisocyanate And aromatic diisocyanates having 8 to 30 carbon atoms such as diphenylmethane diisocyanate and diphenyl propane diisocyanate.

As an isocyanate compound whose number of isocyanate groups in one molecule is three or more, aromatic polyisocyanate, aliphatic polyisocyanate, and alicyclic polyisocyanate are mentioned, for example. Specifically, 2,4,6- triiso cyanate toluene, 1,3,5- triiso cyanate benzene, 4,4 ', 4 "-triphenyl methane tri isocyanate is mentioned. .

Moreover, as an isocyanate compound (B1), the multimer (for example, a dimer, a trimer, a biuret, an isocyanurate) of the said isocyanate compound whose isocyanate group number is two or three or more, for example. Sieve), derivatives (for example, addition reaction products of polyhydric alcohols and two or more diisocyanate compounds), and polymers. As a polyhydric alcohol in the said derivative, As a low molecular weight polyhydric alcohol, trihydric or more alcohol, such as trimethylol propane, glycerin, pentaerythritol, is mentioned, for example; As a high molecular weight polyhydric alcohol, a polyether polyol, polyester polyol, an acryl polyol, polybutadiene polyol, polyisoprene polyol is mentioned, for example.

As such an isocyanate compound, the burette of the trimer of diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, hexamethylene diisocyanate, or tolylene diisocyanate, for example Reaction products of a sieve or isocyanurate, trimethylolpropane with tolylenediisocyanate or xylylenediisocyanate (for example tolylenediisocyanate or xylylenediisocyanate) Trimolecular adducts of anate), reaction products of trimethylolpropane with hexamethylenediisocyanate (e.g. trimolecular adducts of hexamethylenediisocyanate), polyether polyisocyanate Anate, polyester polyisocyanate is mentioned.

Among the isocyanate compounds (B1), an aliphatic diisocyanate crosslinking agent is preferable, and a hexamethylene diisocyanate crosslinking agent is more preferable from the viewpoint of improving durability (such as foaming resistance and moisture heat whitening resistance). Do. As an aliphatic diisocyanate type crosslinking agent, an aliphatic diisocyanate and its multimer are mentioned, for example. As a hexamethylene diisocyanate type crosslinking agent, hexamethylene diisocyanate, its biuret body, or isocyanurate body is mentioned, for example.

An isocyanate compound (B1) may be used individually by 1 type, and 2 or more types may be used.

<< metal chelate compound (B2) >>

As the metal chelate compound (B2), for example, alkoxide, acetylacetone, ethyl acetoacetate, and the like are assigned to polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium and zirconium. A compound is mentioned. Among these, especially an aluminate compound (M-12AT by Soken Kagaku Corporation etc.) is preferable. Specifically, aluminum isopropylate, aluminum secondary tilate, aluminum ethyl acetoacetate diisopropylate, aluminum trisethyl acetoacetate, and aluminum trisacetyl acetonate are mentioned.

A metal chelate compound (B2) may be used individually by 1 type, and may use 2 or more types.

<< epoxy compound (B3) >>

As the epoxy compound (B3), an epoxy compound having two or more epoxy groups in one molecule is usually used. For example, 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'-tetraglycidylamino Phenylmethane, triglycidyl isocyanurate, mN, N- diglycidylaminophenylglycidyl ether, N, N- diglycidyl toluidine, N, N- diglycidyl aniline Can be.

[Silane Coupling Agent (C)]

It is preferable that the adhesive composition of this invention contains a silane coupling agent (C) further. The silane coupling agent (C) contributes to improving the durability of the pressure-sensitive adhesive layer, firmly adhering the pressure-sensitive adhesive layer to adherends such as glass plates, and preventing peeling under a high humidity heat environment.

As a silane coupling agent (C), For example, Alkyl groups, such as methyl trimethoxysilane, dimethyldimethoxy silane, methyl triethoxy silane, phenyl trimethoxy silane, and phenyl triethoxy silane, or Aromatic group-containing silane coupling agent; Keto group-containing silane coupling agents such as 3-acetoacetylpropyltrimethoxysilane; Vinyltrimethoxysilane, vinyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane Polymerizable unsaturated group-containing silane coupling agents such as phosphorus and 3-methacryloxypropyltriethoxysilane; 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, Epoxy group-containing silane coupling agents such as 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3- Amino groups, such as aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, and N-phenyl-3-aminopropyltrimethoxysilane Silane coupling agents; Halogen-containing silane coupling agents, such as 3-chloropropyl trimethoxysilane, are mentioned.

Content of the silane coupling agent (C) in the adhesive composition of this invention is 1 mass part or less normally with respect to 100 mass parts of (meth) acrylic-type copolymers (A), Preferably it is 0.01-1 mass part, More preferably Preferably it is 0.05-0.5 mass part. When content exists in the said range, peeling of a to-be-adhered body in a high humidity heat environment, and bleeding of the silane coupling agent (C) in a high temperature environment tend to be prevented.

[Organic Solvent (D)]

It is preferable that the adhesive composition of this invention contains an organic solvent (D) in order to adjust the applicability | paintability. As an organic solvent (D), the polymerization solvent demonstrated in the column of a (meth) acrylic-type copolymer (A) is mentioned. For example, the adhesive composition can be prepared by mixing the crosslinking agent and the solution containing the copolymer obtained by the said copolymerization and a polymerization solvent. In the adhesive composition of this invention, content of an organic solvent is 20-90 mass% normally, Preferably it is 30-70 mass%.

[additive]

The pressure-sensitive adhesive composition of the present invention is one or more selected from antioxidants, light stabilizers, metal corrosion inhibitors, tackifiers, plasticizers, antistatic agents, crosslinking accelerators and rework agents within the range not impairing the effects of the present invention other than the above components. You may contain 2 or more types.

[Preparation of Adhesive Composition]

The adhesive composition of this invention can be prepared by mixing a (meth) acrylic-type copolymer (A), a crosslinking agent (B), and another component by a conventionally well-known method as needed. For example, what mix | blends a crosslinking agent (B) and another component as needed in the solution containing the said copolymer and polymerization solvent obtained when synthesize | combining a (meth) acrylic-type copolymer (A) is mentioned.

Preferably the gel fraction of the adhesive formed from the adhesive composition of this invention is 10-60 mass%, More preferably, it is 15-50 mass%, More preferably, it is 20-40 mass%. The said gel fraction is a value measured about the adhesive collected by the conditions described in an Example, for example.

[Adhesive layer]

The adhesive layer of this invention is formed from the adhesive composition mentioned above.

In the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition of the present invention, the gel fraction is preferably 10 to 60% by mass, more preferably 15 to 50% by mass, even more preferably 20 to 40% by mass, from the viewpoint of cohesion, adhesion and re-peelability. %to be.

The adhesive layer formed from the adhesive composition of this invention has low dielectric constant, and the dielectric constant in frequency 100Hz becomes like this. Preferably it is 5.0 or less, More preferably, it is 2.0-4.5, More preferably, it is 2.0-4.0. The adhesive layer whose relative dielectric constant exists in the said range can be used suitably for a touch panel use, for example.

Since the adhesive layer of this invention is excellent in flexibility, when affixing an adhesive sheet to a to-be-adhered body, heating and / or pressurizing (for example, temperature 50-90 degreeC, 2-10 atmospheres), the followability with respect to the step which an adherend has has It is improving. For example, when affixing an adhesive sheet with respect to a to-be-adhered body, such as a support body in which a printed layer was formed, the base material in which an electroconductive thin film was formed, etc., the adhesive layer of this invention shows the outstanding step | following followability. In addition, since the pressure-sensitive adhesive layer once followed by the step has sufficient flexibility in a high temperature environment, lifting and peeling of the pressure-sensitive adhesive layer from the step portion hardly occurs even when exposed to a high temperature environment.

The pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition of the present invention is excellent in durability.

For example, even when the pressure-sensitive adhesive layer is placed under a high temperature and high humidity heat environment, problems such as foaming at the interface with the adherend, heat insulation of the pressure-sensitive adhesive layer, and lifting and peeling of the adherend are unlikely to occur.

Further, for example, the pressure-sensitive adhesive layer having a film thickness of 50 µm has an absolute value of a difference in haze value between before and after stationary (before and after the endurance test) even after standing for 24 hours (after the endurance test) in an 85 ° C / 85% RH environment. Usually, it is 0.5% or less, More preferably, it is 0.3% or less, and it is excellent in whitening prevention property. In addition, "%" here is a unit of a haze value. For this reason, even when the said adhesive layer is used for an image display apparatus or an input apparatus, the visibility of an image display part is excellent.

The detail of the measurement conditions of a dielectric constant and a haze value is as having described in the Example.

The adhesive layer of this invention is obtained by crosslinking a (meth) acrylic-type copolymer (A) with a crosslinking agent (B) specifically by advancing the crosslinking reaction in the above-mentioned adhesive composition, for example.

Formation conditions of an adhesive layer are as follows, for example. Although the adhesive composition of this invention is apply | coated on a support body, and it changes also with kinds of solvent, Usually, it is dried at 50-150 degreeC, Preferably it is 60-100 degreeC, for 1 to 5 minutes normally, Preferably it is 3 to 5 minutes drying The solvent is removed to form a coating film. The film thickness of a dry coating film is 10-300 micrometers normally, Preferably it is 20-180 micrometers.

It is preferable to form an adhesive layer on condition of the following. After apply | coating the adhesive composition of this invention on a support body, and sticking a cover film on the coating film formed on the said conditions, it is usually 3 days or more, Preferably it is 7-10 days, Usually 5-60 degreeC, Preferably it is 15- Curing is carried out in an environment of 40 ° C, usually 20 to 80% RH, preferably 30 to 70% RH. If crosslinking is carried out under the aging conditions as described above, it is possible to efficiently form a crosslinked product (network polymer).

As a coating method of an adhesive composition, it is apply | coated so that it may become predetermined thickness by a well-known method, for example, a spin coating method, the knife coating method, the roll coating method, the bar coating method, the blade coating method, the die coating method, the gravure coating method, etc. The method of drying can be used.

As a support body and a cover film, For example, Polyester films, such as polyethylene terephthalate (PET); Plastic films, such as polyolefin film, such as polyethylene, a polypropylene, and ethylene-vinyl acetate copolymer, are mentioned.

[Adhesion sheet]

The adhesive sheet of this invention has an adhesive layer formed from the said adhesive composition. As an adhesive sheet, for example, the single-sided adhesive sheet which has a double-sided adhesive sheet which has only the said adhesive layer, a base material, the double-sided adhesive sheet which has the said adhesive layer formed on both surfaces of a base material, the base material, and the said adhesive layer formed in one surface of a base material. And the adhesive sheet which affixed the cover film which peeled on the surface which is not in contact with the base material of the adhesive layer of these adhesive sheets.

As a base material and a cover film, For example, Polyester films, such as polyethylene terephthalate (PET); Plastic films such as polyethylene, polypropylene, polycarbonate (PC), and polyolefin films such as ethylene-vinyl acetate copolymers; Thin film glass, and the like.

The film thickness of the pressure-sensitive adhesive layer can be determined in consideration of, for example, the step (step difference followability) and transparency of the surface of the adherend. The film thickness of an adhesive layer is 10-300 micrometers normally, Preferably it is 20-180 micrometers. Although the film thickness of a base material and a cover film is not specifically limited, Usually, 5-1000 micrometers, Preferably it is 10-700 micrometers.

[Application use]

The pressure-sensitive adhesive composition, pressure-sensitive adhesive layer or pressure-sensitive adhesive sheet of the present invention is an input device such as a touch panel having a manufacturing use of an image display device such as a liquid crystal display device, an electronic paper, an optical method, an ultrasonic method, a capacitance method, a resistive film method, or the like. It can be used suitably for the manufacturing use of. In particular, it is used suitably for the manufacturing use of a capacitive touch panel.

The pressure-sensitive adhesive composition, pressure-sensitive adhesive layer or pressure-sensitive adhesive sheet of the present invention can be suitably used for laminating applications with a support and a substrate with a conductive thin film formed of a conductive thin film (for example, an electrode or a wiring pattern) made of a metal or a metal oxide on the surface of the substrate. have.

As a support body, it is a glass plate, for example; And transparent plastic films such as polyethylene terephthalate (PET), polycarbonate (PC), and polymethyl methacrylate (PMMA). The thickness of a support body is 25-2000 micrometers normally.

The support body may have a printed layer in order to improve designability of a liquid crystal display device, a touch panel, etc. in the peripheral part of the surface which contacts an adhesive layer. The thickness of a printed layer is 10-50 micrometers normally, and the cross section of a printed layer is rectangular shape, for example.

As a conductive thin film which comprises a base material with a conductive thin film, the thin film which consists of a metal, a metal oxide, or a mixture thereof is mentioned, for example, A transparent thin film which consists of indium tin oxide (ITO), antimony tin oxide (ATO), tin oxide, etc. Can be mentioned. The thickness of a conductive thin film is 10-200 nm normally. As a base material which comprises a base material with an electroconductive thin film, transparent plastic films, such as a polyethylene terephthalate film, are mentioned, for example. The thickness of a base material is 25-1000 micrometers normally.

When the adhesive layer which consists of an adhesive composition of this invention is arrange | positioned so that a support body and a base material with an electroconductive thin film may be adhere | attached, this adhesive layer is in direct contact with the electroconductive thin film formed in the base material with an electroconductive thin film, and the printing layer is formed in the support body. Is also in direct contact with the printed layer.

As described above, the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition of the present invention does not form voids even when there is a step based on an electrode wiring pattern or a printed layer. Moreover, the said adhesive layer is excellent also in low dielectric constant and durability.

Moreover, in this invention, since it can be set as the structure which does not contain an acidic radical substantially in an adhesive layer, even if an adhesive layer directly contacts the conductive thin film which consists of a metal or a metal oxide, corrosion of a conductive thin film is prevented and the resistance value The rise of can be suppressed. For this reason, in the capacitive touch panel, the pressure-sensitive adhesive layer is in direct contact with the conductive thin film forming the electrode / wiring pattern having a step, but the pressure-sensitive adhesive layer has the advantage that the characteristics of the conductive thin film are not changed.

(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 the following Examples etc., unless otherwise indicated, "part" shows a "mass part."

[Average molecular weight]

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

Measuring device: HLC-8120GPC (manufactured by Tosoh Corporation)

GPC column structure: The following five consecutive columns (all manufactured by Tosoh Corporation)

(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: 1.0 mg / cm ³ (dilute with tetrahydrofuran)

Mobile phase solvent: Tetrahydrofuran

Flow rate: 1.0 cm ³ / min

Column temperature: 40 ° C

Example 1

35 parts of isodecyl methacrylate (IDMA), 60 parts of isostearyl acrylate (ISTA), 2-hydroxyethyl methacrylate (2HEMA) in a reaction apparatus equipped with a stirrer, a reflux cooler, a thermometer and a nitrogen introduction tube It heated up at 80 degreeC, introducing 4 parts, 1 part of acrylamide (AM), and 70 parts of ethyl acetate solvents, and introducing nitrogen gas. Next, 0.3 part of azobisisobutyronitrile (AIBN) was added, and the polymerization reaction was performed at 80 degreeC under nitrogen atmosphere for 8 hours. After the completion of reaction, the mixture was diluted with ethyl acetate to prepare a polymer solution having a solid content concentration of 50% by mass. The weight average molecular weight (Mw) of the obtained (meth) acrylic-type copolymer was 350,000, and molecular weight distribution (Mw / Mn) was 12.

HDI type isocyanate compound "24A-100" (Asahi) with respect to the obtained (meth) acrylic copolymer solution (solid content concentration 50 mass%) and 100 parts (solid content) of the (meth) acrylic copolymer contained in the said solution (Asahi 0.2 part of Kasei Chemicals Co., Ltd., 0.2 part of silane coupling agent "KBM-403" (made by Shin-Etsu Silicone Co., Ltd.), and ethyl acetate were mixed, and the adhesive composition of 40 mass% of solid content concentration was obtained.

The obtained adhesive composition was apply | coated at 25 degreeC of liquid temperature so that the thickness after drying might be set to 50 micrometers on the PET film which carried out the peeling process, it dried at 90 degreeC for 4 minutes, the solvent was removed, and the coating film was formed. An adhesive film having a pressure-sensitive adhesive layer having a thickness of 50 µm was further bonded to a PET film having a thickness of 38 µm subjected to the peeling treatment on the surface opposite to the bonding surface of the PET film of the coating film, and aged for 7 days under 23 ° C./50% RH environment. A sheet was obtained.

[Examples 2-25, Comparative Examples 1-16]

Except having used the monomer component of Table 1A, Table 1B, it carried out similarly to Example 1, and obtained the (meth) acrylic-type copolymer solution. Next, except having changed each component like Table 1A and Table 1B, it carried out similarly to Example 1, and obtained the adhesive sheet which has an adhesive composition and an adhesive layer of 50 micrometers in thickness. In Table 1A and Table 1B, the amounts of the crosslinking agent and the silane coupling agent are amounts relative to 100 parts of the (meth) acrylic copolymer. In Examples 12 and 22, the amount of ethyl acetate solvent introduced was changed from 70 parts to 60 parts when preparing the (meth) acrylic copolymer.

Monomer component

Alkyl methacrylate (a1)

IDMA: Isodecyl methacrylate (C10 branched alkyl)

LMA: lauryl methacrylate (C12 linear alkyl)

NSTMA: n-stearyl methacrylate (C18 linear alkyl)

Alkyl acrylate (a2)

ISTA: isostearyl acrylate (C18 branched alkyl)

2EHA: 2-ethylhexyl acrylate (C8 branched alkyl)

IOAA: isooctylacrylate (C8 branched alkyl)

LA: lauryl acrylate (C12 linear alkyl)

NOAA: n-octylacrylate (C8 linear alkyl)

Hydroxyl-containing monomer (a3)

2HEMA: 2-hydroxyethyl methacrylate

2HEA: 2-hydroxyethyl acrylate

Nitrogen atom-containing monomer (a4)

AM: acrylamide

DM: dimethylaminoethyl methacrylate

Other monomer (a5)

NBA: n-butyl acrylate

Crosslinking agent

Hexamethylene diisocyanate (HDI) type isocyanate compound

Duranate `` 24A-100 '' (manufactured by Asahi Kasei Chemicals Co., Ltd.)

Duranate `` TPA-100 '' (manufactured by Asahi Kasei Chemicals Co., Ltd.)

Tolylene diisocyanate (TDI) type isocyanate compound

Coronate L (made by Nippon Polyurethane Co., Ltd.)

Metal chelate compounds

Alumina chelate crosslinking agent "M-12AT" (made by Soken Kagaku Co., Ltd.)

Silane coupling agent

KBM-403 (made by Shin-Etsu Silicone Co., Ltd.)

KBM-603 (made by Shin-Etsu Silicone Co., Ltd.)

[evaluation]

(Durability test: foaming, lifting, moist heat whitening (haze))

The peeling process of the peeling process of the single side | surface of the adhesive sheet obtained by the Example etc. was peeled off, the adhesive layer whole surface was bonded to 100-micrometer-thick PET film, and it cut to the size of 50 mm x 50 mm. Next, the other peeled PET film was peeled off and the exposed pressure-sensitive adhesive layer was bonded to a glass plate, treated with an autoclave of 50 ° C / 5 atm for 20 minutes, and then left to stand in 23 ° C / 50% RH atmosphere for 1 hour. A test piece was prepared.

(1) The prepared test piece was left to stand in 85 degreeC / 85% RH environment for 24 hours, and the foaming and lifting generate | occur | produced based on the following reference | standard, and evaluated.

AA: No foaming or lifting was observed.

BB: Lifting was not confirmed, but very fine foaming was confirmed.

CC: Clear foaming or lifting was confirmed.

(2) After measuring the haze before the endurance test of the created test piece, it stood still for 24 hours in 85 degreeC / 85% RH environment. After taking out a test piece and letting it stand at room temperature for 1 hour, haze was measured and the difference ((Day haze; unit%) of haze before and after an endurance test was calculated | required. MH-150 (made by Murakami Shikisai Jutsu Kenkyujo Co., Ltd.) was used for the measurement of haze.

[Relative dielectric constant]

Two adhesive sheets obtained in Examples and the like were prepared, and the peeled PET films were peeled from each other, and then the pressure-sensitive adhesive layers were bonded to each other to prepare a pressure-sensitive adhesive sheet having a thickness of 100 μm, and then the pressure-sensitive adhesive layer was placed on a copper foil having a thickness of 100 μm. Transfer was carried out, the copper foil of thickness 100micrometer was further stuck on this adhesive layer, and it was set as the measurement sample. The dielectric constant (100 Hz) was computed in 23 degreeC / 50% RH atmosphere by connecting to copper foil using the LCR meter 6440B by Toyo Technica.

[Gel fraction]

From the pressure-sensitive adhesive sheet obtained in Examples and the like, about 0.1 g of the pressure-sensitive adhesive was taken into a sampling bottle, and 30 mL of ethyl acetate was added thereto, followed by shaking for 4 hours, and then the contents of the sample bottle were filtered through a 200 mesh stainless steel metal mesh, The residue was dried at 100 ° C. for 2 hours to measure the dry weight, and the gel fraction was determined by the following equation. Moreover, the gel fraction was calculated | required in the same manner to the above about the adhesive collected from the adhesive sheet which left still for 30 days in 23 degreeC / 50% RH environment after 7 days aging in 23 degreeC / 50% RH environment mentioned above.

Gel fraction (%) = (weight after drying / weight of adhesive collected) x 100 (%)

(180 ° peeling force (adhesive force))

The peeling process PET film of the one side of the adhesive sheet obtained by the Example etc. was peeled off, the adhesive layer whole surface was bonded to 100-micrometer-thick PET film, it cut out at 25 mm x 150 mm, and the test piece was created. Subsequently, the other peeled PET film was peeled off, and the pressure-sensitive adhesive layer exposed was bonded to a glass plate, and pressed for three round trips with a roller having a weight of 2 kg. After standing for 2 hours in a 23 ° C./50% RH atmosphere after pressing, the short side of the test piece was pulled in the 180 ° direction at a peel rate of 300 mm / min, and the force to start peeling was set to 180 ° peel force (adhesive force). Moreover, the adhesive force was calculated | required similarly to the above also about the adhesive sheet which left still for 30 days in 23 degreeC / 50% RH environment after aging in 23 degreeC / 50% RH environment mentioned above for 7 days.

[Step followability]

The peeling process PET film of the one side of the adhesive sheet obtained by the Example etc. was peeled off, the adhesive layer whole surface was bonded to a 100-micrometer-thick PET film, it cut out at 50 mm x 50 mm, and created the test piece. Next, a PET film having a thickness of 15 μm or 25 μm cut to 15 mm × 15 mm was placed on a glass plate, the other peeled PET film of the test piece was peeled off, and the adhesive layer was formed on the entire surface of the PET film (15 mm × 15 mm) on the glass plate. The test piece (50 mm x 50 mm) was affixed so that it might cover and after 20 minutes process with the autoclave of 50 degreeC / 5atm, it left still at room temperature for 1 hour, and the appearance of the step part was visually observed.

"X": Clear bubbles were observed in the stepped portions in any of 15 μm and 25 μm steps.

"15 micrometers": Bubbles were observed at a 25 µm step, but not at 15 µm.

"25 micrometers": No bubble was confirmed in any of 15 micrometers and 25 micrometer step | steps.

In addition, when "(triangle | delta)" is attached to evaluation of "15 micrometer" and "25 micrometer," it shows that a bubble was confirmed to the step part a little in the said step.

The above evaluation results are shown in Table 2A and Table 2B.

Claims (10)

(A) (meth) acrylic copolymer,
(B) cross-linking system
It is an adhesive composition containing
The said copolymer (A) with respect to 100 mass% of all monomer components,
(a1) 20-39 mass% of alkyl methacrylates whose carbon number of an alkyl group is ten or more,
(a2) 30-60 mass% of alkylacrylates whose carbon number of an alkyl group is 8 or more,
(a3) 1-20 mass% of hydroxyl-containing monomers,
(a4) 0-5 mass% of nitrogen atom containing monomers
It is a copolymer obtained by copolymerizing the monomer component containing,
In the monomer component which forms the said copolymer (A), the said alkyl groups which alkyl methacrylate (a1) and alkyl acrylate (a2) have are all linear alkyl groups, or all are branched alkyl groups.
Pressure-sensitive adhesive composition, characterized in that. delete The monomer composition which forms the said copolymer (A) WHEREIN: The hydroxyl-containing monomer (a3) is hydroxyl-containing (meth) acrylate, The adhesive composition of Claim 1 characterized by the above-mentioned. The adhesive composition of Claim 1 whose usage-amount of an acidic radical containing monomer (a6) is 0.1 mass% or less with respect to 100 mass% of all monomer components which form the said copolymer (A). The pressure-sensitive adhesive composition according to claim 1, wherein the weight average molecular weight (Mw) measured by gel permeation chromatography of the copolymer (A) is 30000 to 500000 in terms of polystyrene. (C) The silane coupling agent according to claim 1
Pressure-sensitive adhesive composition, characterized in that it further contains. The pressure-sensitive adhesive composition according to claim 1, wherein the gel fraction of the pressure-sensitive adhesive formed from the pressure-sensitive adhesive composition is 10 to 60 mass%. The pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition according to any one of claims 1 to 3. It has the adhesive layer of Claim 8, The adhesive sheet characterized by the above-mentioned. The base material with an electroconductive thin film in which the support body, the adhesive layer of Claim 8, and the electroconductive thin film which consists of a metal or a metal oxide is formed in this order is laminated | stacked in this order, The laminated body for touch panels characterized by the above-mentioned.