JPH08151560A - Repetitively releasable adhesive and adhesive material - Google Patents

Abstract

PURPOSE: To provide a repetitively releasable adhesive comprising an acrylic copolymer which is prepared from a specific acrylic monomer and a specific imide monomer and has a specific solubilization fraction, thus having humidity resistance and improved repetitive releasability. CONSTITUTION: This adhesive comprises (A) 50-98wt.% of an acrylic monomer of the formula: Ch2 =C(R<1> )COOR<2> (R<1> is H, methyl; R<2> is a 2-14C alkyl) and (B) 50-2wt.% of an imide monomer of the formula I (R<3> is H, a monovalent organic group) or formula II (R<4> is H, a monovalent organic group) wherein the solubilization fraction of this acylic copolymer in ethyl acetate is adjusted to less than 40%, preferably less than 30%, particularly less than 10% at 20 deg.C. Further, (C) monomers other than the components A and B, for example, (meth) acrylic acid or maleic acid may be added thereto in an amount of less than 30wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a removable pressure sensitive adhesive having excellent moisture resistance and a pressure sensitive adhesive member thereof.

[0002]

2. Description of the Related Art An adhesive, or its adhesive member, has been used for various purposes in various fields because of its advantages such as simplicity and good work hygiene that do not require a coating and drying process at the work site. In response, various things have been developed and proposed. Among them, acrylic adhesives containing acrylic polymer as the main component are excellent in light / weather resistance, oil resistance, aging resistance, heat resistance, and adhesive properties such as adhesive force and cohesive force, so that they can be used for plastic and paper. It is used for a wide range of applications by attaching it to a supporting base material made of, for example.

Some of the major uses of such pressure-sensitive adhesives are that they are required to be temporarily adhered for the purpose of surface protection and the like and to be removable again as required. That is, for example, it is temporarily attached to an adherend composed of various articles such as a metal plate, a decorative plate, a glass plate and a plastic plate as a surface protective material to prevent damage, adhesion of dust, deterioration due to oxidation, etc. When the adherend is put to practical use after the end of its purpose, there is an essential application in which the surface protective material and the like are peeled off again.

The adhesive in the re-peelable pressure-sensitive adhesive member retains a sufficient adhesive force so as not to be peeled off at the time of temporary attachment, while contaminants such as a paste component are adhered to the adherend during re-peeling. It is strongly desired that it can be easily re-peeled without remaining in the second step from the viewpoint of omitting the cleaning step after the peeling.

However, the conventional acrylic re-peelable pressure-sensitive adhesives have the drawbacks that the adhesive force to the adherend increases with time and the efficiency of the peeling work decreases, and the re-peeling becomes difficult. It was In addition, there is a problem that problems such as adhesive residue that leaves contaminants on the adherend after peeling are likely to occur.

It has been attempted to improve the cohesive force and the like by copolymerizing an acrylic polymer with a polar group-containing monomer to overcome the above-mentioned problems, but the problem is that the moisture resistance of the pressure-sensitive adhesive is deteriorated. was there. If the moisture resistance is poor, the adhesive strength will change significantly over time in a humid environment, and the advantages of acrylic re-peelable adhesives, which have poor reliability in outdoor use and excellent light and weather resistance, can be fully utilized. Will not be done.

[0007]

DISCLOSURE OF THE INVENTION The present invention has improved removability without impairing the adhesive properties such as light / weather resistance, oil resistance, aging resistance, heat resistance and the like, and without lowering moisture resistance. The development of the above-mentioned acrylic adhesive and its adhesive member is an object.

[0008]

The present invention provides a compound of the general formula (A); CH ₂ ═C (R ¹ ) COOR ² (wherein R ¹ is hydrogen or a methyl group, and R ² has 2 to 14 carbon atoms). 50 to 98% by weight of an acrylic monomer represented by the formula (B) or (C); (However, R ³ or R ⁴ is hydrogen or a monovalent organic group.) It is composed of 50 to 2% by weight of an imide monomer and has a soluble fraction of 40% in ethyl acetate at 20 ° C.
A releasable pressure-sensitive adhesive characterized by containing less than the acrylic copolymer as a component, and a pressure-sensitive adhesive member characterized by having a layer comprising the pressure-sensitive adhesive on a supporting substrate.

[0009]

[Function] By using the pressure-sensitive adhesive having the above-mentioned constitution using an acrylic copolymer having an imide-based monomer as a copolymer component and having a soluble fraction of less than a predetermined value, moisture resistance is not deteriorated. It is possible to overcome problems such as increase in adhesive strength to adherends over time and problems with adhesive residue after peeling and improve re-peeling performance, and to improve adhesive properties such as light resistance, weather resistance, oil resistance, aging resistance, and heat resistance. It is possible to obtain an excellent re-release type acrylic re-release type pressure-sensitive adhesive. Although the reason is not clear, it is considered that it is due to the excellent water resistance of the imide-based monomer and the generation of appropriate cohesive force in the removable pressure-sensitive adhesive due to the appropriate polarity of the monomer.

[0010]

Examples of constituent elements of the invention The removable adhesive of the present invention is
Formula _{(A); CH 2 = C} (R 1) COOR 2 ( where
R ¹ is hydrogen or a methyl group, and R ² is an alkyl group having 2 to 14 carbon atoms. ) Acrylic monomer 50-
98% by weight of the general formula (B) or (C); (However, R ³ or R ⁴ is hydrogen or a monovalent organic group.) It is composed of 50 to 2% by weight of an imide monomer and has a soluble fraction of 40% in ethyl acetate at 20 ° C.
Less than the acrylic copolymer.

The acrylic monomer represented by the above general formula (A) has R ² of, for example, an ethyl group,
Propyl group, butyl group, isobutyl group, isoamyl group,
Of acrylic acid or methacrylic acid having an alkyl group having 2 to 14 carbon atoms such as hexyl group, 2-ethylhexyl group, heptyl group, isooctyl group, isononyl group, isodecyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group. Examples include esters.

When the carbon number of R ² in the general formula (A) is less than 2, the glass transition temperature (Tg) becomes high and the wettability as a pressure-sensitive adhesive decreases and the tack (initial adhesiveness) becomes poor. On the other hand, when the carbon number of R ² exceeds 14, the adhesive strength of the pressure-sensitive adhesive becomes poor.

[0013] On the other hand, the monomer represented by the general formula (B) is a maleimide compound, a monomer represented by the general formula (C) is a itaconimide compound, the R ³ or R ⁴ May be hydrogen or a monovalent organic group. Therefore, when R ³ or R ⁴ is hydrogen, the monomer represented by the general formula (B) is maleimide itself, and the monomer represented by the general formula (C) is
The monomer represented by is itaconimide itself.

On the other hand, examples of R ³ or R ⁴ consisting of a monovalent organic group include an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, and those in which a functional group is further introduced. Be done. Specific examples of R ³ or R ⁴ include methyl group, ethyl group, propyl group, isopropyl group, butyl group, hexyl group, 2-ethylhexyl group,
Octyl group, lauryl group, cyclohexyl group, phenyl group, methylphenyl group, methoxyphenyl group, chlorophenyl group, nitrophenyl group, carboxyphenyl group,
Examples thereof include a hydroxyphenyl group.

The acrylic copolymer used in the present invention contains 50 to 98% by weight, preferably 60 to 97% by weight of the above-mentioned acrylic monomer component represented by the general formula (A), and has the general formula ( 50 to 2% by weight, preferably 40 to 3% by weight, of the imide-based monomer component represented by B) or (C),
Particularly, it is composed of an acrylic copolymer containing 30 to 3% by weight.

When the content of the acrylic monomer component in the acrylic copolymer is less than 50% by weight, the Tg becomes high, the wettability as an adhesive decreases, and the tack becomes poor. If it exceeds%, the content of the imide-based monomer component represented by the general formula (B) or (C) is poor, and it becomes difficult to achieve both adhesive properties and moisture resistance. On the other hand, if the content of the imide-based monomer component exceeds 50% by weight, it is difficult to maintain a low Tg and the tack tends to be poor.

The acrylic copolymer used in the present invention includes
The acrylic monomer represented by the general formula (A) and the other type of monomer as the D component which can be copolymerized with the imide monomer represented by the general formula (B) or (C). It can also be copolymerized. Copolymerization ratio of D component is 30% by weight
Hereafter, 25% by weight or less is preferable. If the copolymerization ratio exceeds 30% by weight, the above-mentioned performance of the acrylic polymer such as light resistance and weather resistance becomes difficult to be expressed,
It may be difficult to balance the properties of the removable adhesive.

The monomer used as the component D may be any one that can be copolymerized with the acrylic monomer or imide monomer. Examples thereof include carboxyl group-containing monomers such as (meth) acrylic acid, carboxyethyl (meth) acrylate, maleic acid, itaconic acid, and crotonic acid, and acid anhydride-based monomers such as maleic anhydride and itaconic anhydride. The body is raised.

Further, 2- (meth) acrylamide-2-
Sulfonic acid-containing monomers such as methylpropanesulfonic acid, phosphoric acid-containing monomers such as 2-hydroxyethyl (meth) acryloyl phosphate, N-substituted (meth) s such as (meth) acrylamide and N, N-dimethylacrylamide Amide-based monomers such as acrylamide, amino group-containing monomers such as diaminoethyl (meth) acrylate,
Examples of the D component include vinyl acetate, styrene and its derivatives, vinyl monomers such as N-vinylpyrrolidone and N-vinylcarboxylic acid amides.

Further, hydroxyl group-containing monomers such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 2-hydroxybutyl (meth) acrylate, (meth) acrylonitrile, (meth).
Such as glycidyl acrylate, methyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, (poly) fluorinated (meth) acrylate and silicone (meth) acrylate Other than the acrylic monomer represented by the general formula (A), a (meth) acrylic acid ester-based monomer and the like are also included as the D component.

In addition, the itaconic imide-based monomer represented by the general formula (C) or the itaconic imide-based monomer represented by the general formula (C) with respect to the maleimide-based monomer represented by the general formula (B). A maleimide-based monomer represented by the formula (B) may also be used as the D component.

In the above, when the acrylic copolymer is crosslinked through an intermolecular crosslinking agent, for example, a carboxyl group-containing monomer represented by (meth) acrylic acid or maleic anhydride or an acid anhydride is used. And a monomer having a functional group capable of reacting with an intermolecular crosslinking agent, such as a hydroxyl group-containing monomer typified by 2-hydroxyethyl (meth) acrylate or glycidyl (meth) acrylate. It can be particularly preferably used as the D component.

The above-mentioned intermolecular cross-linking agent is, for example, a polyfunctional isocyanate compound, a polyfunctional epoxy compound, a polyfunctional melamine compound, a polyfunctional compound represented by a peroxide or a metal salt. Various compounds can be used, and any known intermolecular crosslinking agent can be used.

On the other hand, it is also possible to prepare a copolymer composition in which the acrylic copolymer can be crosslinked through the component D, for example, by radiation such as an electron beam without using the intermolecular crosslinking agent as described above. In that case, as the self-crosslinking type D component, for example, a monomer having two or more bonding hands is used.

Specific examples of the self-crosslinking type D component include:
Hexanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, trimethylolpropane Examples thereof include tri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, and dipentaerythritol hexa (meth) acrylate.

Further, epoxy (meth) acrylate such as glycidyl (meth) acrylate, polyester (meth) acrylate, urethane (meth) acrylate, N
-Acrylamide compounds such as methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide,
Polyfunctional alkoxysilanes such as propyltrimethoxysilane (meth) acrylate, propyldimethoxysilane (meth) acrylate, propyltriethoxysilane (meth) acrylate, and divinylbenzene are also mentioned as the self-crosslinking D component. .

The imide-based monomer represented by the general formula (B) or (C) forming the acrylic copolymer is functionalized as R ³ or R ⁴ such as a carboxyphenyl group or a hydroxyphenyl group. When it has a group and can be crosslinked with an intermolecular crosslinking agent, an acrylic copolymer which can be crosslinked without using the component D can be obtained. Therefore, in the present invention, an acrylic copolymer containing no D component may also be used.

The acrylic copolymer used in the present invention can be prepared, for example, by using one type or two types for forming the copolymer.
Appropriate methods such as a solution polymerization method, an emulsion polymerization method, a bulk polymerization method and a suspension polymerization method can be applied to a mixture of each kind of monomer or more. In the case of the bulk polymerization method, a polymerization method using ultraviolet irradiation can be preferably applied.

In the above-mentioned polymerization treatment, a suitable polymerization initiator such as a thermal polymerization initiator or a photopolymerization initiator depending on the polymerization method can be used if necessary. The amount used may be determined as appropriate, but generally it is 0.00 of the total amount of monomers to be copolymerized.
It is set to 1 to 5% by weight.

Examples of the above thermal polymerization initiator include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate and di (2-ethoxy). Ethyl) peroxydicarbonate, t
Organic peroxides such as -butylperoxyneodecanoate, t-butylperoxybibalate, di (3,5,5-trimethylhexanoyl) peroxide, dilauroyl peroxide, dipropionyl peroxide and diacetyl peroxide And so on.

Further, 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane1-carbonitrile) and 2,2 ' -Azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxyvaleronitrile) or dimethyl-2,2 '
-Azobis (2-methylpropionate), 4,4'-
Examples of the thermal polymerization initiator include azo compounds such as azobis (4-cyanovaleric acid) and 2,2′-azobis (2-hydroxymethylpropionitrile).

On the other hand, examples of the photopolymerization initiator include 4-
(2-Hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone and α-hydroxy-α, α'-
Dimethylacetophenone, methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1
-Ketone or acetophenone compounds such as -hydroxycyclohexyl phenyl ketone and 2-methyl-1- [4- (methylthio) -phenyl] -2-morpholinopropane-1, benzoin ether compounds such as benzoin ethyl ether and benzoin isopropyl ether And so on.

Further, ketal compounds such as benzyl dimethyl ketal, benzophenone and benzoylbenzoic acid, benzophenone compounds such as 3,3'-dimethyl-4-methoxybenzophenone, thioxanthone and 2-.
Chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-
Examples of the photopolymerization initiator include thioxanthone compounds such as diethylthioxanthone and 2,4-diisopropylthioxanthone, and compounds such as camphorquinone, halogenated ketones, acylphosphinoxides, and acylphosphonates. To be

The re-peelable pressure-sensitive adhesive of the present invention, when subjected to a crosslinking treatment, has a soluble fraction of the acrylic copolymer in ethyl acetate at 20 ° C. of less than 40%, preferably less than 30%, and particularly less than 10%. It was prepared as follows. When the soluble fraction is 40% or more, the adhesive strength with respect to the adherend tends to increase with time.

In the re-peelable pressure-sensitive adhesive which suppresses the increase in the adhesive force with time, the adhesive force to the adherend can be increased as the soluble fraction is increased. Therefore, as the soluble fraction is gradually decreased from 40%, the adhesive strength to the adherend can be decreased, and while maintaining the suppressive property of the adhesive strength required for re-peelable pressure-sensitive adhesives with time. , The adhesion to the adherend can be adjusted. For customary applications that do not require high adhesion to adherends, those having the soluble fraction adjusted to less than 10% can be generally preferably used.

Incidentally, 100 parts by weight of an acrylic copolymer prepared by using 80 parts by weight of 2-ethylhexyl acrylate, 10 parts by weight of cyclohexylmaleimide, and 3 parts by weight of acrylic acid were mixed with 3 parts by weight of a tetrafunctional epoxy crosslinking agent. By carrying out a crosslinking treatment in part, the soluble fraction of the acrylic copolymer with respect to ethyl acetate at 20 ° C. can be adjusted to 4.3%.

The above soluble fraction is 16 parts by weight of 1 part by weight of the acrylic copolymer to 100 parts by weight of ethyl acetate at 20 ° C.
After soaking for 8 hours, the solution was filtered through a 250 mesh filter cloth made of polyamide or the like, and the dry weight of the acrylic copolymer (insoluble matter) that could not be filtered in that case was measured and calculated from the weight. The soluble content of the acrylic copolymer can be calculated as a percentage.

As described above, the removable adhesive of the present invention is
As a composition that can be crosslinked by an appropriate method such as a method of blending an intermolecular crosslinking agent, a method of copolymerizing a self-crosslinking monomer, or a composite method using them in combination, the pressure-sensitive adhesive can be used in a predetermined amount as described above. Crosslinking treatment was carried out within the range of the dissolution fraction.

In the above, the method using an intermolecular crosslinking agent is as follows:
It is mixed with an adhesive to form a crosslinked adhesive through heat treatment or irradiation treatment with radiation such as ultraviolet rays and electron beams. The blending amount of the intermolecular crosslinking agent can be appropriately determined depending on the type and content of the functional group in the acrylic copolymer that reacts with the intermolecular crosslinking agent. Generally, 0.01 to 20 parts by weight, and especially 0.5 to 15 parts by weight are used per 100 parts by weight of the acrylic copolymer.

The removable pressure-sensitive adhesive of the present invention is based on, for example, a solution type of an acrylic copolymer dissolved in an appropriate organic solvent, a solution type based on a solution polymerization solution, an emulsion polymerization solution or a suspension polymerization solution, and the like. It can be prepared in an appropriate form such as an emulsion or dispersion type. In its preparation, if necessary, for example, natural or synthetic resins, glass fibers or beads, fillers made of metal powder or other inorganic powder, additives such as pigments and colorants, antioxidants, etc. An appropriate compounding agent that may be compounded with the pressure-sensitive adhesive may be added.

The pressure-sensitive adhesive member of the present invention comprises a support substrate and a layer comprising the removable pressure-sensitive adhesive. As the supporting base material, a suitable thin film made of a plastic film, paper, woven cloth, non-woven cloth, foam, metal foil or the like is generally used. The surface of the supporting substrate can be subjected to appropriate treatment such as corona discharge treatment or adhesion strengthening treatment with a primer or the like. For a supporting base material made of a non-polar substance such as polyethylene or polypropylene, it is effective to apply an adhesion strengthening treatment to prevent the problem of adhesive residue.

The pressure-sensitive adhesive layer may be provided on the supporting base material by applying the pressure-sensitive adhesive on the supporting base material by an appropriate method such as a casting method or a coating method, and then performing a necessary treatment such as a drying treatment or a crosslinking treatment. Or a method of forming a pressure-sensitive adhesive layer by applying a separator, for example, a thin sheet subjected to a surface treatment with a release agent, polypropylene, a pressure-sensitive adhesive layer formed according to the above on a weakly adhesive film such as polyester. It can be carried out by an appropriate method such as a method of transferring onto a supporting base material.

The thickness of the pressure-sensitive adhesive layer may be appropriately determined according to various uses such as surface protection, masking, or elep. Generally, the thickness is 1 to 500 μm. The pressure-sensitive adhesive layer may be partially provided on the supporting substrate as a dot-like distribution state or the like.

[0044]

According to the present invention, since an acrylic copolymer having a specific imide monomer as a copolymer component is used, light resistance / weather resistance, oil resistance, aging resistance, heat resistance, etc. It is possible to obtain a highly reliable re-peelable pressure-sensitive adhesive having excellent adhesive property, excellent moisture resistance property, little change with time of adhesive force to various adherends, and easy re-peeling.

[0045]

【Example】

Example 1 A container equipped with a thermometer, a reflux condenser, a nitrogen inlet and a stirrer was charged with 150 parts of ethyl acetate (parts by weight, the same applies hereinafter), and 80 parts of 2-ethylhexyl acrylate, 10 parts of cyclohexylmaleimide, Acrylic acid copolymer solution was obtained by adding 3 parts of acrylic acid and 0.5 part of azobisisobutyronitrile and polymerizing under nitrogen substitution and stirring at 60 ° C. for 4 hours and then at 80 ° C. for 2 hours. (Polymerization rate 99
%).

Next, to the above-mentioned acrylic copolymer solution, 3 parts of a tetrafunctional epoxy crosslinking agent per 100 parts of the acrylic copolymer was added to prepare an adhesive solution, which was prepared to a thickness of 2
Apply on a 5μm polyester film and apply 2 at 80 ℃.
It was dried for 0 minutes to obtain an adhesive member having an adhesive layer with a thickness of 10 μm.

Example 2 An adhesive solution and an adhesive member were obtained in the same manner as in Example 1 except that the amount of cyclohexylmaleimide used was 20 parts.

Example 3 An adhesive solution and an adhesive member were obtained in the same manner as in Example 1 except that the amount of cyclohexylmaleimide used was 30 parts.

Example 4 A pressure-sensitive adhesive solution and a pressure-sensitive adhesive member were obtained in the same manner as in Example 1 except that 20 parts of lauryl maleimide was used instead of cyclohexylmaleimide.

Example 5 An adhesive solution and an adhesive member were obtained in the same manner as in Example 1 except that 20 parts of butyl maleimide was used instead of cyclohexyl maleimide.

Example 6 A pressure-sensitive adhesive solution and a pressure-sensitive adhesive member were obtained in the same manner as in Example 1 except that 20 parts of isopropylmaleimide was used instead of cyclohexylmaleimide.

Example 7 N-acrylic acid was used instead of 2-ethylhexyl acrylate.
A pressure-sensitive adhesive solution and a pressure-sensitive adhesive member were obtained in the same manner as in Example 1 except that -butyl was used.

Example 8 An adhesive solution and an adhesive member were obtained in the same manner as in Example 1 except that 10 parts of octylitaconimide was used instead of cyclohexylmaleimide.

Example 9 An adhesive solution and an adhesive member were obtained in the same manner as in Example 8 except that the amount of octylitaconimide used was 20 parts.

Example 10 An adhesive solution and an adhesive member were obtained in the same manner as in Example 8 except that the amount of octyl itaconimide used was 30 parts.

Example 11 An adhesive solution and an adhesive member were obtained in the same manner as in Example 8 except that 20 parts of butylitaconimide was used instead of octylitaconimide.

Example 12 An adhesive solution and an adhesive member were obtained in the same manner as in Example 8 except that 20 parts of lauryl itaconimide was used instead of octyl itaconimide.

Example 13 An adhesive solution and an adhesive member were obtained in the same manner as in Example 8 except that 20 parts of cyclohexylitaconimide was used instead of octylitaconimide.

Example 14 A pressure-sensitive adhesive solution and a pressure-sensitive adhesive member were obtained in the same manner as in Example 2 except that the amount of the tetrafunctional epoxy crosslinking agent used was 1 part.

Example 15 A pressure sensitive adhesive solution and a pressure sensitive adhesive member were obtained in the same manner as in Example 2 except that the amount of the tetrafunctional epoxy crosslinking agent used was 0.5 part.

Comparative Example 1 An adhesive solution and an adhesive member were obtained in the same manner as in Example 1 except that 20 parts of N-vinylpyrrolidone was used instead of cyclohexylmaleimide.

Comparative Example 2 A pressure sensitive adhesive solution and a pressure sensitive adhesive member were obtained in the same manner as in Example 1 except that 20 parts of acrylamide was used instead of cyclohexylmaleimide.

Comparative Example 3 An adhesive solution and an adhesive member were obtained in the same manner as in Example 1 except that 20 parts of acrylic acid was used without using cyclohexylmaleimide.

Comparative Example 4 A pressure-sensitive adhesive solution and a pressure-sensitive adhesive member were obtained in the same manner as in Example 2 except that the amount of the tetrafunctional epoxy crosslinking agent used was 0.04 part.

Comparative Example 5 A pressure sensitive adhesive solution and a pressure sensitive adhesive member were obtained in the same manner as in Example 2 except that the amount of the tetrafunctional epoxy crosslinking agent used was 0.1 part.

Comparative Example 6 A pressure-sensitive adhesive solution and a pressure-sensitive adhesive member were obtained in the same manner as in Comparative Example 4 except that 20 parts of octylitaconimide was used instead of cyclohexylmaleimide.

Evaluation Test The following characteristics of the pressure-sensitive adhesive solutions and pressure-sensitive adhesive members obtained in Examples and Comparative Examples were examined. Dissolvable Fraction A pressure-sensitive adhesive layer was formed on a separator instead of the polyester film in accordance with the pressure-sensitive adhesive member of each Example and each Comparative Example, and 1 g of the pressure-sensitive adhesive layer was collected from the separator and then 2
After immersing in 100 g of ethyl acetate at 0 ° C. for 168 hours, the solution was filtered through a 250-mesh polyamide filter cloth, and the dry weight of the insoluble matter that could not be filtered in that case was measured to determine the solubility. Minutes were calculated as a percentage.

Adhesive strength 1 Adhesive member with a width of 20 mm on a stainless steel plate (SUS 304 BA)
Move the kg rubber roller back and forth once and press it,
The force required for peeling was measured (180 degree peeling, peeling speed 3
(00 mm / min, 20 ° C).

Water resistance The above preserved product was immersed in distilled water at 20 ° C. for 4 days and taken out, and the state of the adhesive member was examined.

The above results are shown in Tables 1 and 2. From the table, it can be seen that the removable pressure-sensitive adhesive of the present invention shows good removable performance and is excellent in moisture resistance.

[Table 1]

[0071]

[Table 2]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hozumi Tanaka 1-2-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation (72) Yuko Yamamoto 1-21-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation (72) Inventor Kyoko Izumi 1-2-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation

Claims (3)

[Claims] 1. 50 to 98% by weight of an acrylic monomer represented by the following general formula (A) and the general formula (B) or (C).
Consisting of 50 to 2% by weight of an imide monomer represented by
A removable pressure-sensitive adhesive, which comprises an acrylic copolymer having a soluble fraction of less than 40% in ethyl acetate at 20 ° C. Formula _{(A); CH 2 = C} (R 1) COOR 2 ( where
R ¹ is hydrogen or a methyl group, and R ² is an alkyl group having 2 to 14 carbon atoms. ) General formula (B); (However, R ³ is hydrogen or a monovalent organic group.) General formula (C); (However, R ⁴ is hydrogen or a monovalent organic group.) 2. An acrylic monomer represented by the general formula (A) and another kind of monomer copolymerizable with the imide monomer represented by the general formula (B) or (C) in an amount of 30% by weight. % Or less, and the re-peelable pressure-sensitive adhesive according to claim 1, which comprises an acrylic copolymer as a component. 3. A pressure-sensitive adhesive member comprising a support base material and a layer comprising the removable pressure-sensitive adhesive according to claim 1 or 2.