TWI404782B - Pressure sensitive adhesive composition, product using the same, and display using the product - Google Patents

Abstract

An adhesive composition is provided to ensure coatability, adhesive property, transparency, antifoaming property, releasability and anti-corrosive property and to improve optical property like visibility. An adhesive composition comprises an acrylic polymer having the average molecular weight of 400,000-1,600,000 and a crosslinking agent. The acrylic polymer comprises (A) alkoxyalkylacrylate and (B) acrylic monomer having a cross-linkable functional group. The content of the component A is 45-99.5 parts by weight and the content of the component B is 0.5-4.5 parts by weight, based on the total monomer component 100.0 parts by weight.

Description

Adhesive composition and adhesive article and display using same

This invention relates to an acrylic adhesive composition. In detail, the present invention relates to adhesion, foaming/peeling resistance, transparency, and coating of transparent plastics such as glass and acrylic polymers, polycarbonate, and polyethylene terephthalate (PET). Excellent in cloth properties, especially an adhesive composition which does not corrode a metal film. Further, the present invention relates to an adhesive article coated with the adhesive composition and a display in which the adhesive product is bonded.

In recent years, FPD (Flat Panel Display), which is led by a liquid crystal display (LCD), has been widely used. FPD can be produced by laminating an optical film having various functions through an adhesive (pressure-sensitive adhesive). In these applications, the adhesive is required to have excellent reliability in terms of adhesion, transparency, and properties such as foaming or peeling (foaming resistance/peeling resistance) under conditions such as high temperature or high humidity. Sex.

Since the prior art, as a method of improving foaming/peelability in a high-temperature, high-humidity environment, a method is known in which a monomer exhibiting a high glass transition temperature (Tg) by a homopolymer (high Tg) A method of increasing the Tg of the adhesive by copolymerizing a monomer or a monomer having a functional group such as a carboxyl group, and adding an oligomer (low molecular weight polymer).

For example, it is known that a polymer containing a carboxyl group-containing monomer as a constituent component and an oligomer containing an amine group-containing monomer as a constituent component are used for adhesiveness and foaming resistance to plastic at normal temperature and high temperature. An adhesive composition excellent in properties (refer to Patent Document 1). Also, it is known that it will be heavier in a specific weight ratio a (meth) acrylate polymer (A) having a weight average molecular weight of 500,000 to 2.5 million and a (meth) acrylate polymer (B) having a weight average molecular weight of 5,000 to 500,000, and (A) (B) Each of the adhesive compositions having a nitrogen-containing functional group (see Patent Document 2). Further, there is known an adhesive composition and an adhesive sheet using the same, which comprises: 100 parts by weight of an alkoxyalkyl (meth)acrylate as a main component, and a carboxyl group-containing monomer An adhesive polymer obtained by copolymerization therewith; 5 to 40 parts by weight of one or more selected from the group consisting of alkyl methacrylate, cycloalkyl methacrylate, benzyl methacrylate or styrene The monomer is a main component, and a low molecular weight polymer obtained by copolymerizing an amine group or a mercapto group-containing monomer; and 0.001 to 2.0 parts by weight of a crosslinking agent (refer to Patent Document 3).

However, since these adhesive compositions have an increased Tg of the adhesive, there is a problem in that the subsequent properties are lowered under low temperature or high speed conditions. Further, the adhesive composition containing a carboxyl group-containing monomer has a problem that corrosion resistance is insufficient when it is attached to a metal thin film (including a metal oxide film). That is, an excellent adhesive composition capable of achieving high levels of foaming/peeling resistance in a high-temperature and high-humidity environment, adhesion characteristics in a low-temperature region, and corrosion resistance has not been obtained.

[Patent Document 1] Japanese Patent No. 3516035 (Patent Document 2) Japanese Patent Laid-Open No. 2001-89731 (Patent Document 3) Japanese Patent Laid-Open Publication No. 2002-327160

It is an object of the present invention to provide an adhesive composition for coating It is excellent in properties, adhesion, transparency, foaming resistance/peelability, and excellent in corrosion resistance. Further, an object of the present invention is to provide an adhesive article or a display having high reliability using the above adhesive composition.

Further, depending on the use, there is a case where it is required to suppress the yellowing of the adhesive. For example, when an aromatic isocyanate compound is used as a crosslinking agent or the like, yellow may become a problem and a corresponding countermeasure may be required. As a method of suppressing such yellowing, it is effective to use an aliphatic isocyanate crosslinking agent, but in this case, there is a case where the crosslinking speed becomes very slow and there is a problem in productivity. Generally, the adhesive sheet can be promoted by heating to promote the crosslinking reaction. However, since it is strictly required for appearance in display applications, there is a case where it is difficult to use a method which facilitates generation and promotes heating of the dents to promote crosslinking.

Therefore, another object of the present invention is to provide an adhesive composition which is excellent in yellowing resistance and productivity, and an adhesive article or display using the same.

The present inventors have conducted intensive studies to achieve the above object, and as a result, it has been found that an acrylic polymer having a specific molecular weight of an alkoxyalkyl acrylate as a main monomer has a crosslinked structure, and it is possible to obtain a composition containing no acrylic acid or the like. The carboxyl monomer component is also satisfied with an adhesive composition which is resistant to foaming/peelability at a high temperature, and thus the present invention has been completed.

Further, it has been found that by using a specific amount of an aliphatic isocyanate crosslinking agent and an amine compound containing a plurality of hydroxyl groups, yellowing can be suppressed, and adhesion which is excellent in productivity can be obtained without promoting crosslinking by heating. Agent group Compound.

That is, the present invention provides an adhesive composition comprising an alkoxyalkyl acrylate (ingredient A) and an acrylic monomer (component B) having a crosslinkable functional group as a necessary single sheet. The acrylic polymer having a weight average molecular weight of 400,000 to 1.6 million and a crosslinking agent, and the content of the component A is 45 to 99.5 by weight based on 100 parts by weight of all the monomer components constituting the acrylic polymer. The content of the component B is 0.5 to 4.5 parts by weight, and the monomer component constituting the acrylic polymer does not substantially contain a carboxyl group-containing monomer.

Further, the present invention provides the above-mentioned adhesive composition as an essential monomer component with an alkoxyalkyl acrylate (ingredient A) and an acrylic monomer having a crosslinkable functional group (ingredient B). 100 parts by weight of the acrylic polymer having a weight average molecular weight of 400,000 to 1.6 million, 0.01 to 3.0 parts by weight of an aliphatic isocyanate crosslinking agent, and 0.01 to 5.0 parts by weight of an amine compound containing a plurality of hydroxyl groups The adhesive composition has a component A content of 45 to 99.5 parts by weight, and a component B content of 0.5 to 4.5 parts by weight, based on 100 parts by weight of all the monomer components constituting the acrylic polymer, and constitutes an acrylic polymer. The monomer component does not substantially contain a carboxyl group-containing monomer.

Further, the present invention provides the above adhesive composition, wherein the component B is an acrylic monomer having a hydroxyl group.

Further, the present invention provides the above adhesive composition, wherein the gelation ratio after cross-linking structuring is 40 to 80%.

Moreover, the present invention provides an adhesive article coated with the above adhesive combination.

Further, the present invention provides a display using the above-described adhesive article.

Since the adhesive composition of the present invention has the above-described configuration, it is excellent in coatability, adhesion (especially low-temperature adhesion property), transparency, and foaming resistance/peelability, and is therefore used for bonding a display or the like. In the case of the optical member to be used, optical characteristics such as visibility of the product can be improved. Further, since the metal thin film (including the metal oxide thin film) is not corroded, it can be used for a layer in which a film of a metal thin film such as an ITO (indium tin oxide) film is laminated.

Further, by using a specific amount of an aliphatic isocyanate crosslinking agent and an amine compound containing a plurality of hydroxyl groups, yellowing resistance can be improved, and productivity can be improved even when heating is not performed, so that it is particularly suitable. Used for such demanding applications.

[Adhesive Composition]

The adhesive composition of the present invention is composed of an acrylic polymer and a crosslinking agent as essential components.

The acrylic polymer used in the adhesive composition of the present invention is a polymer composed of an alkoxy alkyl acrylate (hereinafter sometimes referred to as "component A") as a main monomer component. Further, in addition to the above-mentioned main monomer component, an acrylic monomer having a crosslinkable functional group (excluding a carboxyl group) (hereinafter sometimes referred to as "component B") may be contained as an essential component. Copolymerization of monomer components. Other monomer components may also be used as needed. Further, the acrylic polymer does not substantially contain a monomer having a carboxyl group as a monomer component.

The alkoxyalkyl acrylate (component A) is not particularly limited, and examples thereof include 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, and methoxytriethylene glycol acrylate. , 3-methoxypropyl acrylate, 3-ethoxypropyl acrylate, 4-methoxybutyl acrylate, 4-ethoxybutyl acrylate, and the like. The above component A may be used singly or in combination of two or more.

In the acrylic polymer, the monomer ratio of the component A as the main monomer component is 45 to 99.5 parts by weight, preferably 50 to 80 parts by weight, based on 100 parts by weight of all the monomer components. When the content of the component A is less than 45 parts by weight in all the monomer components, the foaming resistance/peelability is insufficient. On the other hand, when it exceeds 99.5 parts by weight, the content of the component B is lowered, the cross-linking structure in the polymer is insufficient, and the foaming/peeling resistance is insufficient. In addition, the monomer ratio is a ratio (mixing ratio) of the amount of each monomer component when the acrylic polymer is produced. The other monomer ratios and monomer contents are also the same.

The functional group which is crosslinkable in the acrylic monomer (component B) having a crosslinkable functional group is a functional group other than a carboxyl group, and is a functional group crosslinkable with the following crosslinking agent, There is no particular limitation, and examples thereof include a glycidyl group, an amine group, an N-hydroxymethylguanamine group, and a hydroxyl group. Specific examples of the component B include the following examples. Examples of the monomer having a glycidyl group include glycidyl (meth)acrylate and shrinkage of (meth)acrylic acid. Glyceryl methyl ester; as the monomer having an amine group, N-N-dimethylaminoethyl (meth)acrylate, N-N-diethylaminoethyl (meth)acrylate Examples of the monomer having an N-hydroxymethylguanamine group include N-methylol acrylamide; and examples of the monomer having a hydroxyl group include 2-hydroxyethyl (meth)acrylate and (methyl) ) 3-hydroxypropyl acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, and the like. Preferred among them are a monomer having an N-hydroxymethylguanamine group, an acrylic monomer having a hydroxyl group, more preferably an acrylic monomer having a hydroxyl group, and particularly preferably 2-hydroxyethyl acrylate ( 2HEA), 4-hydroxybutyl acrylate (4HBA), 3-hydroxypropyl acrylate (3HPA), and 6-hydroxyhexyl acrylate (6HHA). In addition, "(meth)acrylic" means "acrylic acid" and / or "methacrylic acid". The same is true below.

In the acrylic polymer, the monomer ratio of the component B is from 0.5 to 4.5 parts by weight, preferably from 0.5 to 3.0 parts by weight, more preferably from 0.5 to 2.0 parts by weight, per 100 parts by weight of the total monomer component. In the case where the content of the component B in all the monomer components is less than 0.5 part by weight, the cross-linking structuring in the polymer may become insufficient, resulting in easy foaming. On the other hand, if it exceeds 4.5 parts by weight, the crosslinked structure may become too tight, and peeling may easily occur.

In the acrylic polymer, a monomer having a carboxyl group is not substantially contained as a monomer component. In addition, the term "substantially not contained" means that it is not actively blended in addition to the case where it is inevitably mixed, and specifically, it is preferably 0.05 parts by weight or less based on 100 parts by weight of all the monomer components. It is less than 0.01 parts by weight, more preferably less than 0.001 parts by weight. Inclusion In the case of a carboxyl group monomer, the corrosion resistance to the metal film is lowered (for example, the conductivity of the ITO film or the like is lowered). Further, examples of the carboxyl group-containing monomer include acrylic acid (AA), methacrylic acid, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Further, it may be an acid anhydride containing such a carboxyl group-containing monomer (for example, an acid anhydride group-containing monomer such as maleic anhydride or itaconic acid anhydride) as a carboxyl group-containing monomer.

In the acrylic polymer, examples of the other monomer component used in addition to the component A and the component B include an alkyl (meth)acrylate having an alkyl group having 1 to 12 carbon atoms, for example, (methyl). Methyl acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, second butyl (meth)acrylate, tert-butyl (meth)acrylate, Amyl (meth)acrylate, isoamyl (meth)acrylate, neopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, Isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, decyl (meth)acrylate, (methyl) Isodecyl acrylate, eleven (meth) acrylate, dodecyl (meth) acrylate, and the like. Other examples include alkoxyalkyl methacrylate such as methoxyethyl methacrylate or ethoxyethyl methacrylate; triethylene glycol diacrylate and ethylene glycol dimethacrylate; A polyfunctional monomer such as an ester or trimethylolpropane tri(meth)acrylate; vinyl acetate, styrene, cyclohexyl (meth)acrylate or the like.

In view of suppressing the glass transition temperature (Tg) of the acrylic polymer to a low level, it is preferred that the above-mentioned other monomer component is a single Tg having a Tg of 0 ° C or less. Body, better Tg is -40 Monomer below °C. For example, 2-ethylhexyl acrylate (2EHA), butyl acrylate (BA) and the like are preferred.

The acrylic polymer can be produced by a polymerization method well known or customary. Examples of the polymerization method of the acrylic polymer include a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, or a polymerization method by irradiation with ultraviolet rays, and are preferable in terms of transparency, water resistance, cost, and the like. It is a solution polymerization method, a UV polymerization method, and particularly preferably a solution polymerization method.

The polymerization initiator to be used in the solution polymerization of the acrylic polymer is not particularly limited, and may be appropriately selected from known or customary polymerization initiators. For example, 2,2'-azobis is preferably exemplified. Isobutyronitrile, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis (2,4,4- Azo-based polymerization initiators such as trimethylpentane) and 2,2'-azobis(2-methylpropionate); benzamidine peroxide, tert-butyl hydroperoxide, and dimethoate Tributyl peroxide, tert-butyl peroxybenzoate, dicumyl peroxide, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, An oil-soluble polymerization initiator such as a peroxide-based polymerization initiator such as 1,1-bis(t-butylperoxy)cyclododecane. The polymerization initiators may be used singly or in combination of two or more. The amount of the polymerization initiator to be used may be a usual amount, and may be, for example, selected from the range of about 0.01 to 1 part by weight based on 100 parts by weight of all the monomer components.

Further, various common solvents can be used in the solution polymerization. Examples of such a solvent include esters such as ethyl acetate and n-butyl acetate; toluene and benzene; An aromatic hydrocarbon; an aliphatic hydrocarbon such as n-hexane or n-heptane; an alicyclic hydrocarbon such as cyclohexane or methylcyclohexane; a ketone such as methyl ethyl ketone or methyl isobutyl ketone; Organic solvents. The solvent may be used singly or in combination of two or more.

The weight average molecular weight of the acrylic polymer (hereinafter sometimes referred to simply as the molecular weight) is 400,000 or more and 1.6 million or less (400,000 to 1.6 million), preferably 600,000 to 1,200,000, more preferably 600,000 to 1,000,000. . When the weight average molecular weight of the acrylic polymer is less than 400,000, the adhesive force and cohesive force which are necessary as an adhesive are not obtained, and the foaming/peeling resistance is insufficient. On the other hand, if it exceeds 1.6 million There is a problem that the coating property is poor due to an increase in the viscosity of the adhesive.

Further, the above weight average molecular weight (Mw) can be measured by a gel permeation chromatography (GPC) method. More specifically, the product name "HLC-8120GPC" (manufactured by Tosoh Co., Ltd.) can be used as a GPC measuring device, and the weight average molecular weight can be determined by measuring the polystyrene-converted value under the following GPC measurement conditions.

GPC measurement conditions

. Sample concentration: 0.2% by weight (tetrahydrofuran solution). Sample injection amount: 10 μl. Dissolution: tetrahydrofuran (THF). Flow rate (flow rate) = 0.6 mL/min. Column temperature (measuring temperature): 40 ° C. Pipe column: trade name "TSK gel Super HM-H/H4000/H3000/H2000" (manufactured by Tosoh Co., Ltd.) . Detector: Differential Refractometer (RI)

The weight average molecular weight of the acrylic polymer can be controlled by the kind of the polymerization initiator or the amount thereof to be used, the temperature or time during polymerization, the monomer concentration, the monomer droplet acceleration, and the like.

The glass transition temperature (Tg) of the acrylic polymer is improved from the viewpoint of improving the adhesive property at a low temperature or the characteristics at a high speed (for example, a property of not causing peeling when the bonded constituent falls) (falling impact property) Good is -40~-70 °C, more preferably -50~-70 °C. Further, the Tg of the acrylic polymer is a glass transition temperature (theoretical value) represented by the following formula.

1/Tg=W ₁ /Tg ₁ +W ₂ /Tg ₂ +...+W _n /Tg _n

In the above formula, Tg represents the glass transition temperature (unit: K) of the acrylic polymer, Tg _n represents the glass transition temperature (unit: K) of the homopolymer of the monomer n, and W _n represents the weight percentage of the monomer n.

The storage modulus of the acrylic polymer at 80 ° C is preferably 0.01 MPa or more, more preferably 0.03 MPa or more. Further, the storage elastic modulus is determined by laminating the adhesive layer to a thickness of about 1.5 mm, and then using an "Advanced Rheometric EXpansion System (ARES)" manufactured by Rheometric Scientific Co., Ltd. at a frequency of 1 Hz. . Further, the measurement was carried out at a temperature rising rate of -70 to 200 ° C and a temperature of 5 ° C /min.

The crosslinking agent used in the adhesive composition of the present invention can be widely used. It is well known in the prior art, and depending on the functional group of the component B, it can be suitably selected from a polyfunctional melamine compound, a polyfunctional epoxy compound, a polyfunctional isocyanate compound, and the like. Choose to use. The crosslinking agent can be used alone or in combination of two or more Mixed use. In the present invention, by using a crosslinking agent to carry out cross-linking structuring, a balance of foaming resistance/peeling resistance can be obtained.

Examples of the polyfunctional melamine compound include methylated trimethylol melamine and butylated hexamethylol melamine. Moreover, examples of the polyfunctional epoxy compound include diglycidyl aniline and glycerin diglycidyl ether. Further, examples of the polyfunctional isocyanate compound include toluene diisocyanate (TDI), diisocyanate-1,6-hexane diester (HDI), polymethylene polyphenyl isocyanate, and diphenylmethane II. Isocyanate, reaction product of trimethylolpropane and toluene diisocyanate, polyether polyisocyanate, polyester polyisocyanate, and the like. Among them, it is preferred to use a monomer having a hydroxyl group as the component B, and a polyfunctional isocyanate compound (isocyanate crosslinking agent) as a crosslinking agent.

In particular, from the viewpoint of improving yellowing resistance (yellowing inhibition), it is preferred to use an aliphatic isocyanate crosslinking agent as a crosslinking agent. As the aliphatic isocyanate crosslinking agent, it is widely known to use it widely, and for example, diisocyanate-1,6-hexane diester, diisocyanate-1,4-butane diester, and preferably Isocyanic acid-2-methyl-1,5-pentane diester, diisocyanate-3-methyl-1,5-pentane diester, leucine diisocyanate, isophorone diisocyanate, diiso Cyclohexyl cyanate, hydrogenated toluene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethyl xylene diisocyanate, and the like. Among them, it is preferred to use a monomer having a hydroxyl group as the component B, and to use Hexamethylene diisocyanate (also including a reaction product obtained using HDI) as a crosslinking agent.

The amount of the crosslinking agent to be used is not particularly limited. For example, it is usually preferably 0.01 to 5 parts by weight, more preferably 0.01 to 3 parts by weight, more preferably 100 parts by weight based on the acrylic polymer. 0.1 to 3 parts by weight, preferably 0.1 to 1.0 part by weight.

In the adhesive composition of the present invention, in order to accelerate the crosslinking reaction, an amine compound containing a plurality of hydroxyl groups can be used. In the case of using an aliphatic isocyanate crosslinking agent as a crosslinking agent, it is particularly preferable to maintain productivity (especially, a crosslinking reaction can be carried out quickly without promoting crosslinking by heating). Use together. The amine-based compound having a plurality of hydroxyl groups is not particularly limited as long as it is an amine-based compound having at least two hydroxyl groups (alcoholic hydroxyl groups) in the molecule. Further, in the amine compound, the number of nitrogen atoms contained in the molecule is also not particularly limited. The above-mentioned amine compound containing a plurality of hydroxyl groups may be used singly or in combination of two or more kinds.

Specific examples of the amine-based compound having a plurality of hydroxyl groups include, as an amine compound having one nitrogen atom in the molecule, diethanolamine, dipropanolamine, diisopropanolamine, and N-methyl. Diethanolamine such as diethanolamine, N-methyldiisopropanolamine, N-ethyldiethanolamine, N-ethyldiisopropanolamine, N-butyldiethanolamine, N-butyldiisopropanolamine Classes; triolamines such as triethanolamine, tripropanolamine, and triisopropanolamine.

In addition, examples of the amine compound having two nitrogen atoms in the molecule include an amine compound represented by the following formula (I).

[Chemical 1]

In the above formula (I), R ¹ , R ² , R ³ and R ⁴ may be the same or different and each represent a hydrogen atom or [-(R ⁵ O) _m (R ⁶ O) _n -H]. Here, R ⁵ and R ^{6 are} different and each represents an alkylene group. m and n are integers of 0 or more, but are not 0 at the same time. Further, at least two of R ¹ , R ² , R ³ and R ⁴ are [-(R ⁵ O) _m (R ⁶ O) _n -H]. Further, X represents a divalent hydrocarbon group, and p is an integer of 1 or more.

In the above formula (I), examples of the alkylene group of R ⁵ and R ⁶ include a methylene group, an exoethyl group, a propyl group, a 1,3-propenyl group, and a 1,4-butylene group. Ethyl extended ethyl, 1,5-extended pentyl, 1,6-extended hexyl and the like having an alkyl group having a carbon number of about 1 to 6 (preferably an alkyl group having a carbon number of 1 to 4, more preferably It is an alkylene group having a carbon number of 2 or 3. The alkylene group may have any form of a linear chain or a branched chain. Among them, as the alkylene group of R ⁵ and R ⁶ , an exoethyl group and a propyl group can be preferably used.

Further, if m and n are integers of 0 or more, it is not particularly limited. For example, at least one of m and n can be selected from the range of 0 to 20, preferably about 1 to 10. Most of m and n are 0 and the other is an integer of 1 or more (especially 1). Further, when m is different from n, it is 0 (when m and n are simultaneously 0, [-(R ⁵ O) _m (R ⁶ O) _n -H] represents a hydrogen atom).

Further, X represents a divalent hydrocarbon group. Examples of the divalent hydrocarbon group include an alkylene group, a cycloalkylene group, and an extended aryl group. The alkyl group of X may be in the form of either a linear chain or a branched chain. Further, it may be in any form of saturation or unsaturated. Examples of the alkylene group of X include a methylene group, an ethyl group, and a propyl group. 1,3-propyl, 1,4-butylene and the like have an alkyl group having a carbon number of about 1 to 6 (preferably, an alkylene group having a carbon number of 1 to 4, more preferably a carbon number of 2 or 3 of the alkyl group) and the like. In addition, examples of the cycloalkyl group include a 1,2-cyclohexylene group, a 1,3-cyclohexylene group, a 1,4-cyclohexylene group, and the like. As the aryl group, for example, 1,2-phenylene, 1,3-phenylene, 1,4-phenylene, and the like can be used.

Further, p is not particularly limited as long as it is an integer of 1 or more. For example, it can be selected from the range of about 1 to 10, preferably an integer of 1 to 6, more preferably an integer of 1 to 4.

More specifically, as the amine compound represented by the above formula (I), for example, except N,N,N',N'-tetrakis(2-hydroxyethyl)ethylenediamine, N,N,N', N'-tetrakis(2-hydroxypropyl)ethylenediamine, N,N,N',N'-tetrakis(2-hydroxyethyl)-1,3-propanediamine, N,N,N',N In addition to '-tetrakis(2-hydroxypropyl)-1,3-propanediamine, a polyoxyethylene condensate of ethylenediamine, a polyoxypropylene condensate of ethylenediamine, and polyoxyethylene of ethylenediamine may also be mentioned. A polyoxyalkylene condensate of an alkylenediamine such as an ethylene-polyoxypropylene condensate. As such an amine-based compound, for example, commercially available products such as "EDP-300", "EDP-450", "EDP-1100", and "Pluronic" (made by ADEKA (manufactured by ADEKA)) can be used.

The amount of the above-described amine compound containing a plurality of hydroxyl groups is preferably 0.01 to 5.0 parts by weight, based on 100 parts by weight of the acrylic polymer, from the viewpoint of promoting the crosslinking reaction and improving the productivity. It is 0.05 to 1.0 part by weight.

In order to accelerate the crosslinking reaction, a crosslinking accelerator other than those disclosed above may be used in the adhesive composition of the present invention. As such a crosslinking accelerator, For example, an amine compound such as N, N, N', N'-tetramethylhexamethylenediamine or imidazole, an amine compound having a plurality of reactive functional groups other than a hydroxyl group, such as cobalt naphthenate An organic metal compound such as dibutyltin diacetate, dibutyltin hydroxide or dibutyltin laurate. These compounds may be used singly or in combination of two or more. The amount of the crosslinking accelerator to be used is, for example, preferably 0.001 to 0.5 part by weight, more preferably 0.001 to 0.3 part by weight, per 100 parts by weight of the acrylic polymer.

In addition to the above, the adhesive composition of the present invention may also contain other common additives, that is, an ultraviolet absorber, a light stabilizer, an anti-aging agent, a peeling adjuster, a tackifier, a plasticizer, a softener, and a filler. Agent, colorant (pigment or dye, etc.), surfactant, and the like.

The adhesive composition of the present invention can be obtained by mixing an acrylic polymer and a crosslinking agent with a hydroxy compound containing a nitrogen atom (especially an amine compound containing a plurality of hydroxyl groups), other crosslinking accelerators or the like. The additives are mixed and prepared.

The gelation ratio of the crosslinked structured adhesive (adhesive after crosslinking) of the present invention is preferably from 40 to 80%, more preferably from the viewpoint of achieving a balance between foaming resistance and peeling resistance. It is 50~70%. The above gel fraction can be obtained as a component insoluble in ethyl acetate, specifically, as a weight percentage of the insoluble component after immersion in ethyl acetate at 23 ° C for 7 days with respect to the sample before impregnation (weight %) and ask for it. The gel fraction can be controlled by the amount of the crosslinking agent added, the content of the component B, and the molecular weight of the polymer component. When the gel fraction is less than 40%, there is a case where foaming tends to occur, and if it exceeds 80%, it is likely to cause "bumping" or "peeling" from the adherend. Happening.

The gel fraction (ratio of the component insoluble in the solvent) is specifically a value calculated by, for example, the following "method for measuring gel fraction".

(Method for measuring gel rate)

The crosslinked structured adhesive (adhesive after crosslinking) was collected: about 0.1 g, and wrapped in a porous tetrafluoroethylene sheet having an average pore diameter of 0.2 μm (trade name "NTF1122", Nitto Denko Co., Ltd. After the company manufactures it, it is bundled with a kite line, and the weight at this time is measured, and this weight is used as the weight before immersion. Further, the weight before the impregnation is the total weight of the adhesive, the tetrafluoroethylene sheet and the kite line. Further, the total weight of the tetrafluoroethylene sheet and the kite line was also measured in advance, and the weight was used as the weight of the package.

Next, the above-mentioned adhesive is wrapped with a sheet of tetrafluoroethylene and bundled with a kite string (hereinafter referred to as "sample"), placed in a 50 ml container filled with ethyl acetate, and allowed to stand at 23 ° C. Set for 7 days. Thereafter, the sample was taken out from the container (after treatment with ethyl acetate), transferred to an aluminum cup, and dried in a drier at 130 ° C for 2 hours. After removing ethyl acetate, the weight was measured. The weight is taken as the weight after impregnation.

Then, the gel fraction was calculated according to the following formula.

Gel fraction (% by weight) = (A - B) / (C - B) × 100 (1)

(In the formula (1), A is the weight after immersion, B is the weight of the package, and C is the weight before immersion.)

For example, it is preferred that the gel fraction of the adhesive when the adhesive composition is crosslinked and structured at 23 ° C for 168 hours satisfies the above range. Further, it is preferably a viscosity when cross-linked structuring is carried out at 50 ° C for 72 hours. The gel fraction of the agent satisfies the above range.

As described above, the previous adhesive (adhesive composition) usually uses an alkyl (meth)acrylate as a main monomer component. However, the acrylic polymer formed from the above adhesive composition has a problem that the storage elastic modulus at a high temperature is lowered, and the foaming/peeling resistance in a high-temperature and high-humidity environment is insufficient. Therefore, in order to improve this property, an adhesive system can be improved by copolymerization of a high Tg monomer or a functional group-containing monomer (a carboxyl group-containing monomer such as acrylic acid) or an oligomer (low molecular weight polymer). The glass transition temperature (Tg) of the whole (acrylic polymer), in turn, increases the molecular weight of the polymer. However, if the Tg of the entire system is increased, the storage elastic modulus of the room temperature region is also increased, so that it is easy to enclose the bubbles at the time of attachment, or to deteriorate the characteristics of low temperature or high speed; When the molecular weight is increased, the viscosity is increased, so that the coating property is lowered and the productivity is deteriorated. Further, in order to achieve the above object, adhesion, or agglomeration, particularly when a carboxyl group-containing monomer such as acrylic acid is used as a monomer component, corrosion resistance when a metal thin film (metal oxide film) is used as an adherend is generated. Reduced problems. In other words, it is impossible to achieve all of the characteristics such as foaming peeling resistance, corrosion resistance, and low temperature properties (low temperature properties) at a high level.

In view of the above, in the present invention, a carboxyl group-containing monomer is not used as a monomer component of an adhesive, and an alkoxyalkyl acrylate having a moderate polarity is used as a main monomer component, and the monomer composition and molecular weight of the adhesive are appropriately adjusted. The degree of cross-linking, whereby the foaming/peeling resistance can be successfully satisfied, and at the same time, the bonding property and corrosion resistance of low temperature and high temperature are achieved. Also borrow In the case of the above composition, for example, when alkoxyalkyl acrylate is copolymerized with a carboxyl group-containing monomer, there is no problem that the viscosity of the polymer is increased due to excessive hydrogen bonding, and further, it is an appropriate molecular weight. An acrylic polymer excellent in coatability was obtained.

The mechanism by which the acrylic polymer constituting the adhesive composition of the present invention exhibits an effect is not clear, and it is presumed as follows. In the present invention, since the alkoxyalkyl acrylate (ingredient A) is used as the main monomer, the Tg of the polymer becomes lower. On the other hand, the effect of the alkoxy group of the alkoxyalkyl acrylate and the specific molecular weight in the present invention can produce a moderate interaction when the polymer composition is polymerized, so that the polymer chain The cross-linking of each other becomes large, and even if the cross-linking of the polymer chain is not easily performed even at a high temperature, the storage elastic modulus of the polymer does not decrease even at a high temperature. Therefore, even at a low Tg and molecular weight, the storage elastic modulus at a high temperature can be maintained at a high level, which can satisfy coating properties and adhesion at low temperatures and high speeds, and can also be realistic at high temperatures. It is resistant to foaming and peeling.

Further, since the acrylic polymer constituting the adhesive composition of the present invention does not contain a carboxyl group-containing monomer as a constituent monomer, the resistance value of the metal thin film (metal oxide thin film) such as ITO caused by the acid component does not occur. The rise can be preferably used in the use of a laminated ITO film or the like. The mechanism for increasing the resistance value is not clear, and it is presumed to be as follows: a carboxyl group-containing monomer remaining as a monomer during polymerization or a low molecular weight polymer soluble in moisture, which is hydrated under high temperature and high humidity conditions. Immersion in the ITO film hinders conduction.

Further, the acrylic polymer constituting the adhesive composition of the present invention contains a specific amount of a monomer (component B) having a crosslinkable functional group such as a hydroxyl group, and is crosslinked by a crosslinking agent, so that a moderate amount can be formed. The degree of crosslinking can thereby exert an effect of preventing foaming or peeling at a high temperature.

Further, by using an aliphatic isocyanate crosslinking agent as a crosslinking agent and adding an amine-based compound containing a plurality of hydroxyl groups, an adhesive composition capable of simultaneously achieving yellowing resistance, productivity, and appearance at a high level can be obtained.

[adhesive products]

The adhesive composition is obtained by applying the above-described adhesive composition of the present invention to a substrate or a release liner to obtain an adhesive. The adhesive article of the present invention may contain, for example, an adhesive sheet, an adhesive tape, or the like. The adhesive article of the present invention may be in the form of a sheet or a strip which is coated with the above-mentioned adhesive composition on a release liner, and which does not have a substrate (without a substrate), and may also be a single substrate. A sheet-like or strip-like form of the adhesive layer composed of the adhesive composition of the present invention is provided on the surface or both sides.

The thickness of the pressure-sensitive adhesive layer (the thickness of the pressure-sensitive adhesive composition after application and drying) is not particularly limited, and is, for example, preferably 5 to 1000 μm, more preferably 10 to 100 μm. Further, the adhesive layer may have any one of a single layer and a laminate.

The gel fraction of the above adhesive layer (crosslinked structured adhesive) is preferably from 40 to 80%, more preferably from the viewpoint of achieving a balance between foaming resistance and peeling resistance. 50~70%.

In the case where the pressure-sensitive adhesive layer is provided on a substrate, the substrate is not particularly limited, and examples thereof include a plastic film, an anti-reflection (AR) film, and a polarizing plate. Various optical films such as phase difference plates. Examples of the material of the plastic film and the like include polyesters such as polyethylene terephthalate (PET), acrylic resins such as polymethyl methacrylate (PMMA), and polycarbonate and triethylene fluorene-based fibers. A plastic material such as a polymer, a polyfluorene, a polyaryl ester, a product name "ARTON (a cyclic olefin polymer, manufactured by JSR)", and a trade name "ZEONOR (a cyclic olefin polymer, manufactured by Zeon, Japan)". Further, the plastic materials may be used singly or in combination of two or more. The thickness of the above substrate is not particularly limited, and is preferably, for example, 10 to 1000 μm. Further, the substrate may have any one of a single layer and a plurality of layers. Further, on the surface of the substrate, for example, a physical treatment such as a corona discharge treatment or a plasma treatment, a chemical treatment such as a primer treatment, or the like, which is well known or conventional surface treatment, can be carried out.

Further, in the production of the adhesive article of the present invention, the coating of the adhesive composition may be carried out by a well-known coating method, and a conventional coating machine such as a gravure roll coater, a reverse roll coater, a touch roll may be used. Coating machine, dip roll coater, bar coater, knife coater, sprayer, etc.

The adhesive layer portion of the adhesive article of the present invention preferably has a high transparency when used for optical applications such as displays, for example, a total light transmittance in a visible light wavelength region (according to JIS K 7361). The good is 90% or more, and the better is 91% or more. Further, the haze value of the adhesive layer portion in the adhesive article (in accordance with JIS K 7136) is, for example, preferably less than 1.0%, more preferably less than 0.8%. Furthermore, the total light transmittance and the haze value can be applied, for example, to a glass slide (for example, a glass slide having a total light transmittance of 91.8% and a haze value of 0.4%), and a haze meter (for example) is used. Murakami Color Technology The product was manufactured by the research institute and the product name was "HM-150".

The adhesive body of the above-mentioned adhesive product (adhesive sheet, adhesive tape) is not particularly limited, and examples thereof include an acrylic resin plate, a polycarbonate plate, glass, and polyethylene terephthalate.

The adhesive article of the present invention can be preferably used for displays such as a plasma display panel (PDP), a touch panel, and a liquid crystal panel. Among them, from the viewpoint of corrosion resistance, transparency, and adhesion characteristics, it is particularly preferable for use for directly attaching and fixing a metal film to a touch panel or the like.

[Examples]

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to the examples.

Preparation Example 1 of Acrylic Polymer

(acrylic polymer A)

In a separable flask, 70 parts by weight of 2-methoxyethyl acrylate as a monomer component, 29 parts by weight of 2-ethylhexyl acrylate, and 1 part by weight of -4-hydroxybutyl acrylate were charged. The ester was stirred for 1 hour while introducing nitrogen gas as 0.2 by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator and 100 parts by weight of ethyl acetate as a polymerization solvent. After the oxygen in the polymerization system was removed in this manner, the temperature was raised to 63 ° C, and the reaction was carried out for 10 hours, and toluene was added to obtain an acrylic polymer solution having a solid content concentration of 25% by weight (sometimes referred to as "acrylic polymer solution A"). .). The acrylic polymer (may be referred to as "acrylic polymer A") in the acrylic polymer solution A had a weight average molecular weight of 1.5 million.

(acrylic polymer B~K)

As shown in Table 1, the type of the monomer component, the amount of the monomer, and the amount of the solvent (ethyl acetate) were changed to obtain an acrylic polymer solution (may be referred to as "acrylic polymer solution B to K", respectively). . The weight average molecular weight of the acrylic polymer (may be referred to as "acrylic polymer B to K" in each of the acrylic polymer solutions B to K) is shown in Table 1.

Example 1

In terms of a solid content, 0.3 parts by weight of a polyfunctional isocyanate compound (Nippon Polyurethane Industry) was added as a crosslinking agent with respect to 100 parts by weight of the acrylic polymer solution A (100 parts by weight of the acrylic polymer A). ), the trade name "Coronate L"), to prepare an adhesive composition (solution).

The solution obtained above was cast-coated on a surface of a polyethylene terephthalate (PET) film (thickness: 38 μm) which was subjected to release treatment in a thickness of about 25 μm after drying (release liner) The release treated surface of the mat was heated and dried at 130 ° C for 3 minutes, and further aged at 50 ° C for 72 hours to prepare a substrate-free adhesive sheet.

Examples 2 to 8 and Comparative Examples 1 to 5

The adhesive composition and the adhesive sheet were produced in the same manner as in Example 1 except that the type of the acrylic polymer solution and the amount of the crosslinking agent were changed as shown in Table 2.

[Evaluation]

With respect to the adhesive composition and the adhesive sheet obtained in Examples 1 to 8 and Comparative Examples 1 to 5, coating properties, transparency, and adhesion (cold properties) were evaluated by the following measurement methods or evaluation methods. Resistance to foaming and peeling, corrosion resistance Evaluation. Furthermore, the evaluation results are shown in Table 2. Further, the gel fraction of Table 2 is the value of the gel fraction of the adhesive collected from the above adhesive sheet.

(1) Transparency (total light transmittance, haze value)

Each of the adhesive sheets obtained in the examples and the comparative examples was bonded to a glass slide (manufactured by Matsuron Glass Industry Co., Ltd., trade name "S-1111", and the total light transmittance was 91.8%, and the haze value was 0.4%. Then, the PET film was peeled off, and a test piece having a layer structure of an adhesive layer/slide was prepared, and the test piece was measured using a haze meter (manufactured by Murakami Color Research Laboratory, trade name "HM-150"). Haze value (%). In addition, the haze value (%) was obtained by the formula of "diffuse transmittance / total light transmittance × 100".

When the haze value is less than 1.0%, the transparency is good (○); if the haze value is 1.0% or more, the transparency is poor (x).

(2) Coating properties

The adhesive solution (adhesive composition) obtained in the examples and the comparative examples was cast-coated on a release-treated PET film (release liner) at a coating speed of 1 to 10 m/min. When the adhesive sheet was produced, it was judged that the coating property was good (○), and the coating surface was not smooth, and the coating surface was not smooth (×). . Furthermore, the determination was made by visual inspection.

(3) Corrosion resistance

PET film (made by Toray Co., Ltd., trade name "Lumirror S-10 # 25", thickness 25 μm) was attached to the adhesive sheet obtained in the examples and the comparative examples, and cut out to be 20 mm × 50 mm. The test piece is made in the size.

As shown in Figure 1, the conductive PET film (Nitto Denko (share) manufacturing, business A silver paste having a width of 15 mm is applied to both ends of the product name "ELECRYSTA P400L-TNMP" (size: 70 mm × 25 mm), and the release liner is peeled off on the conductive surface (the side of the ITO film formation surface 2). The adhesive surface of the test piece 1 was placed in a respective environment of 60 ° C 95% RH and 80 ° C for 250 hours, and the rate of change in resistance value (%) compared with that immediately after attachment was measured. Further, the resistance value The "DIGITAL MΩ Hi TESTER, Model 3540" manufactured by Hioki Electric Co., Ltd. was used, and the electrodes were attached to the silver paste portion 3 at both ends to measure.

When the rate of change of the resistance value is less than 120%, it is judged that the corrosion resistance is good (○), and when the rate of change of the resistance value is 120% or more, it is determined that the corrosion resistance is poor (x).

Further, the same test was carried out using only the conductive PET film to which the adhesive sheet was not attached as a blank control, and as a result, the change rate of the electric resistance value at 110 ° C was 110%; and the condition at 60 ° C 95% RH The rate of change of the lower resistance value is 120%.

(4) Foam resistance peeling resistance

The adhesive sheet obtained in the examples and the comparative examples was bonded to a PET film (manufactured by Toyobo Co., Ltd., trade name "A4300", thickness: 125 μm) to prepare a film having a width of 100 mm × a length of 100 mm. sheet.

The release liner was peeled off from the film, and bonded to a polycarbonate (PC) plate (manufactured by Teijin Chemical Co., Ltd., trade name "Panlite PC1111", thickness: 1 mm) and fixed to prepare a PET film. / Sample sheet of the layer structure of the adhesive layer / PC board.

The above sample piece was heat-treated in an oven at 80 ° C for 5 hours (heat resistance test). After the heat resistance test, the adhesion interface to the sample piece was visually observed. (The interface between the adhesive layer and the PC board) was observed, and it was judged that the "bubble" or "bumping" was not observed at all, and the foaming peeling property was good (○), and only "bubble" or "bulge" was slightly observed. In the case of the case, it was judged that the foaming peeling resistance was poor (×).

(5) Low temperature follow-up characteristics

As shown in Fig. 2, an acrylic plate 41 (length 70 mm × width 50 mm × thickness 2.0 mm) (manufactured by Mitsubishi Rayon Co., Ltd., trade name "Acrilite"), and PET film (Toyobo) (Production: "A4300, #125") was attached to the surface of an acrylic plate 42 (length: 120 mm × 50 mm), and the adhesive sheet 43 obtained in the examples and the comparative examples was used. (length 10 mm × width 50 mm) was bonded thereto to prepare a sample 4 for measurement. The above-mentioned bonding (crimping) was carried out under the condition of using a 5 kg roller to reciprocate once, and the bonding area was 10 mm × 50 mm.

The sample for measurement was aged in an autoclave at 50 ° C and 5 atm for 30 minutes, and then aged at 50 ° C under normal pressure for 24 hours, and further placed at a measurement temperature (-30 ° C) for 3 hours. It was then used for the measurement.

As shown in FIGS. 3 to 5, the above-mentioned measurement sample was placed on an impact test apparatus, and an impact test was performed every 10 degrees from an angle (measurement angle) of 10 to 90 in an environment of -30 ° C to measure the pressure. The angle at which the wicking plate 41 is peeled off. The details of the above impact test method and test apparatus are as follows.

[Impact test device, test method]

(i) Test device

Fig. 3 is a schematic view showing a test apparatus. The test device 5 is a device that uses a plate thickness of 3 mm and is an L-shaped cross section (one side of the L word and the other side) A rectangular frame made of a stainless steel plate of 25 mm) (1010 mm on the long side and 322 mm on the short side) is perpendicular to the L-shaped plate with a thickness of 6 mm. A rectangular frame made up of a stainless steel flat plate (one side of the L-shape and 50 mm on the other side) made of a stainless steel plate (the long side is 610 mm and the short side is 322 mm), and further, the hinge is used. On the upper end frame 52A of the second angle steel 52, a rectangular frame made of a stainless steel plate having a thickness of 3 mm and having an L-shaped cross section (one side of the L-shape and 25 mm of the other side) is connected ( The third angle steel 53 (total weight 3.3 kg) formed by the upper side frame 53A is formed by rotating the third angle steel 53 with respect to the second angle steel 52.

As shown in FIG. 4, the cross section of the lower end frame 53B of the third angle steel 53 is formed. The sample holding portion was used as a sample to hold the sample for measurement 4 (the portion having a length of 20 mm from the lower end of the acrylic plate 42).

(ii) Test method

In the environment of -30 ° C, as shown in FIG. 5, the third angle steel 53 is raised until it forms a specific angle (α) with the second angle steel 52, and then the hand is released to impact the second angle steel 52. (make it move in the direction of arrow a). Change the angle (α) and do this again.

By the above impact, as shown in FIG. 6, a force (inertial force) is applied to the acrylic plate 41 in the direction of the arrow b in the drawing, and it is determined that the acrylic plate 41 can be self-acrylic by the force. The angle at which the plate 42 is peeled off.

Further, the angle (α) (measurement angle) was measured from an angle (measurement angle) of 10° to 90°, and was increased by 10° each time.

As is clear from the results of Tables 1 and 2, the adhesive composition which satisfies the requirements of the present invention is excellent in applicability, and the adhesive layer and the adhesive sheet formed from the adhesive composition are not high temperature. Produces "bubbles" or "bumps" and is excellent in foaming resistance/peelability. Further, even if it is attached to a conductive film and stored for a long period of time in a high-temperature environment or a high-temperature and high-humidity environment, there is no problem that the adherend is corroded (Example).

Further, in the adhesive sheets of Examples 1, 3, and 8, in the low-temperature adhesion characteristic test (impact test), even when the measurement angle was 90°, no peeling of the acrylic sheet was observed, and excellent low-temperature adhesion characteristics were exhibited. . Further, in Example 2 and Examples 4 to 7, the peeling of the acrylic sheet was observed at a measurement angle of 50°, and excellent low-temperature adhesion characteristics were exhibited. Further, the adhesive sheets of the examples were all excellent in transparency (○).

On the other hand, when the amount of the alkoxyalkyl acrylate as the component A is small (Comparative Examples 1 and 4) or when the molecular weight of the acrylic polymer is too small (Comparative Example 3), foaming resistance is obtained. /Releasability is reduced. Further, when the molecular weight of the acrylic polymer was too large (Comparative Example 5), the coatability was lowered. Further, when acrylic acid (carboxyl group-containing monomer) was used as the monomer component (Comparative Example 2), the problem of corrosion of the adherend occurred when stored for a long period of time in a high-temperature and high-humidity environment.

Then, based on the examples, the effect of improving yellowing resistance and productivity in the case of using an aliphatic isocyanate crosslinking agent and an amine compound containing a plurality of hydroxyl groups will be described. However, the invention is not limited to the embodiments.

Preparation Example 2 of Acrylic Polymer

(acrylic polymer L)

As shown in Table 3, a specific amount of the monomer component and ethyl acetate as a polymerization solvent were placed, and the mixture was placed in a separable flask, and the mixture was stirred for 1 hour while introducing nitrogen gas. After removing the oxygen in the polymerization system, the temperature was raised to 63 ° C, and 0.2 part by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator was charged, and the reaction was carried out for 10 hours, and MEK (methylethyl group) was added. Ketone), an acrylic polymer solution having a solid content concentration of 25% by weight (may be referred to as "acrylic polymer solution L").

(acrylic polymer M~T)

As shown in Table 3, the type of the monomer component, the amount of the monomer, and the amount of the solvent (ethyl acetate) were changed to obtain an acrylic polymer solution (sometimes referred to as "acrylic polymer solution M~T"). .

The weight average molecular weight of the acrylic polymer (may be referred to as "acrylic polymer L to T" in the acrylic polymer solution L to T) is shown in Table 3.

Example 9

In terms of a solid content, 0.7 parts by weight of an aliphatic polyfunctional isocyanate compound (Nippon Polyurethane) as a crosslinking agent is added to 100 parts by weight of the acrylic polymer solution L (100 parts by weight of the acrylic polymer L). Industry (share), trade name "Coronate HL"), 0.3 parts by weight of a polyol obtained by adding propylene oxide to ethylenediamine as a crosslinking aid (Manufactured by ADEKA (trademark), trade name "EDP- 300"), an adhesive composition (solution) was prepared.

The solution obtained above is dried in a thickness of about 25 μm. Cast-coated on a release-treated surface of a polyethylene terephthalate (PET) film (thickness of 38 μm) (release liner) which had been subjected to release treatment, and dried by heating at 130 ° C for 3 minutes. Further, it was aged at 23 ° C for 7 days to prepare a non-substrate adhesive sheet.

Examples 10 to 23 and Comparative Examples 6 to 10

As shown in Tables 4 and 5, the adhesive composition and adhesion were prepared in the same manner as in Example 9 except that the type of the acrylic polymer solution, the type of the crosslinking agent and the crosslinking assistant, and the blending amount were changed. Sheet.

[Evaluation]

With respect to the adhesive composition and the adhesive sheet obtained in the above Examples 9 to 23 and Comparative Examples 6 to 10, applicability, transparency, foam peeling resistance, corrosion resistance, and productivity (crosslinking degree) were evaluated. The rate of improvement), yellowing resistance (b value after long-term heat treatment).

In addition, the measuring method or evaluation method of transparency, coatability, corrosion resistance, and foaming peeling resistance is the same as the above-mentioned evaluation methods (1) to (4). The rate of improvement of the degree of crosslinking and the yellowing resistance are evaluated by the following measurement methods or evaluation methods. The evaluation results are shown in Tables 4 and 5. The gel fractions of Tables 4 and 5 are values of the gel fraction of the adhesive collected from the above adhesive sheet.

(6) Rate of increase in cross-linking degree (productive)

The adhesive composition obtained in the examples and the comparative examples was applied to the release surface of the PET film whose surface was subjected to release treatment, and the film was heated at 130 ° C in a manner of a thickness of about 25 μm after drying. Dry for 3 minutes to form an adhesive layer. The adhesive layer thus obtained is matured under two different curing conditions of 50 ° C for 24 hours and 23 ° C for 168 hours (7 days). A sample of the adhesive (adhesive after crosslinking).

About 0.1 g of each of the above-mentioned curing conditions (50 ° C for 24 hours, 23 ° C for 168 hours) of an adhesive (adhesive after crosslinking) was used, and the gel fraction (weight) was calculated according to the above-mentioned "method of measuring gelation rate". %).

Using the following formula, the gel fraction of the adhesive which is aged at 50 ° C for 24 hours (referred to as "50 ° C 24 hour gel rate"), and the gelation rate of the adhesive which is aged at 168 ° C for 168 hours (called The "increased rate (%) of the degree of crosslinking" was calculated for "23 ° C 168 hours gel rate".

Rate of increase in cross-linking degree (%) = (23 ° C 168 hours gel rate) / (50 ° C 24 hour gel rate) × 100

Further, the increase in the degree of crosslinking as described above indicates that the crosslinking reaction proceeds more easily at room temperature, and the productivity is better.

(7) Yellowing resistance (b value after heat treatment at 80 ° C for 500 hours, b value after heat treatment at 80 ° C for 1000 hours)

After heat treatment of the samples (each of the adhesive sheets obtained in the examples and the comparative examples) under specific conditions (500 ° C for 500 hours, 80 ° C for 1000 hours), they were attached to a glass slide (Songlang Glass Industry ( Manufactured under the trade name "S-1111", the total light transmittance was 91.8%, the haze value was 0.4%), the adhesive layer was peeled off (PET film was peeled off), and the spectrophotometer DOT- manufactured by Murakami Color Research Institute was used. 3C, the b value was evaluated by the L*a*b* color system.

Further, the transparency of the examples was good (○).

From the results of Tables 3 to 5, it is clear that an adhesive composition and an adhesive sheet using a specific amount of an aliphatic isocyanate crosslinking agent and a crosslinking auxiliary agent containing a plurality of hydroxyl group-containing compounds, in addition to coating properties In addition to being excellent in foaming resistance, peeling resistance, and corrosion resistance, yellowing does not occur even after heating for a long period of time, and yellowing resistance is excellent, and the degree of crosslinking can be increased rapidly even at a temperature of 23 ° C. Excellent productivity (Examples 9 to 20).

On the other hand, when an aromatic isocyanate crosslinking agent is used, or when a crosslinking auxiliary agent containing a plurality of hydroxyl group-containing amine compounds is not used in an appropriate amount, the coating property and the foaming resistance are exhibited. Excellent in characteristics such as peeling property and corrosion resistance, but yellowing is slightly noticeable, and the degree of crosslinking is slow, and the crosslinking becomes insufficient when aging at 168 hours at 23 ° C, and cannot be simultaneously high. Productivity under conditions of yellowing resistance and no heating was achieved horizontally (Examples 21 to 23).

Further, when an aliphatic isocyanate crosslinking agent and a crosslinking auxiliary agent containing a plurality of hydroxyl group-containing compounds are used, when component A or component B is not used as a monomer component or acrylic acid is used as a monomer component In the case where the molecular weight of the acrylic polymer is not in an appropriate range, problems such as coatability, foaming resistance, peeling resistance, and corrosion resistance are caused, and the effects of the present invention are not obtained (Comparative Examples 6 to 10).

1‧‧‧ test piece

2‧‧‧ Conductive PET film (exposed portion of the ITO film forming surface)

3‧‧‧ Conductive PET film (silver coating part)

4‧‧‧Sample for measurement

41‧‧‧Acrylic sheet

42‧‧‧Acrylic sheet with PET film bonded to the surface using an adhesive

42a‧‧‧PET film

42b‧‧‧Acrylic sheet

43‧‧‧Adhesive sheets

5‧‧‧ Impact test device

51‧‧‧1st angle steel

52‧‧‧2nd angle steel

52A‧‧‧2nd angle steel upper end frame

53‧‧‧3rd angle steel

53A‧‧‧3rd angle steel upper end frame

53B‧‧‧3rd angle steel lower end frame

‧‧‧‧ Determination angle

a‧‧‧The direction of movement of the 3rd angle steel in the impact test

B‧‧‧ Direction of force applied to the acrylic plate in the impact test

Fig. 1 is a schematic view showing a resistance value measurement sample used in the evaluation of corrosion resistance in the examples.

Figure 2 shows the sample for measurement used in the low temperature adhesion characteristic test. A schematic cross-sectional view (2a) and a schematic front view (2b).

Fig. 3 is a schematic view showing a test apparatus used in a low temperature adhesion characteristic test.

Fig. 4 is a schematic cross-sectional view showing a sample holding portion of the test apparatus of Fig. 3.

Fig. 5 is a schematic view showing a low temperature adhesion characteristic test method (a schematic side view of the test apparatus).

Fig. 6 is a schematic view showing the force applied to the sample for measurement in the low temperature adhesion characteristic test.

1‧‧‧ test piece

2‧‧‧ Conductive PET film (exposed portion of the ITO film forming surface)

3‧‧‧ Conductive PET film (silver coating part)

Claims (8)

An adhesive composition comprising an acrylic polymer having a weight average molecular weight of 400,000 to 1.6 million and a crosslinking agent, the acrylic polymer comprising an alkoxyalkyl acrylate (ingredient A) and The acrylic monomer (component B) having a crosslinkable functional group is an essential monomer component, and the content of the component A is 45 to 99.5 parts by weight based on 100 parts by weight of all the monomer components contained in the acrylic polymer. The content of the component B is 0.5 to 4.5 parts by weight, and the monomer component contained in the acrylic polymer does not substantially contain the carboxyl group-containing monomer. The adhesive composition of claim 1, which is an average weight of the monomer component containing an alkoxyalkyl acrylate (ingredient A) and an acrylic monomer having a crosslinkable functional group (ingredient B) as an essential monomer component. 100 parts by weight of an acrylic polymer having a molecular weight of 400,000 to 1,600,000, 0.01 to 3.0 parts by weight of an aliphatic isocyanate crosslinking agent, and 0.01 to 5.0 parts by weight of an amine compound containing a plurality of hydroxyl groups, relative to acrylic acid 100 parts by weight of all the monomer components contained in the polymer, the content of the component A is 45 to 99.5 parts by weight, and the content of the component B is 0.5 to 4.5 parts by weight, and the monomer component contained in the acrylic polymer is substantially Does not contain carboxyl-containing monomers. The adhesive composition according to claim 1 or 2, wherein the component B is an acrylic monomer having a hydroxyl group. The adhesive composition of claim 1, wherein the gelation ratio after cross-linking structuring is 40 to 80%. The adhesive composition of claim 2, wherein the gelation ratio after cross-linking structuring is 40 to 80%. The adhesive composition of claim 3, wherein the gelation ratio after cross-linking structuring is 40 to 80%. An adhesive article coated with the adhesive composition according to any one of claims 1 to 6. A display using an adhesive article as claimed in claim 7.