WO2002055626A1 - Removable adhesive compositions and process for producing the same - Google Patents

Abstract

Removable adhesive compositions which upon water absorption undergo a decrease in adhesive strength (an adhesive composition removable with water and an adhesive composition removable with water in combination with heat). The removable adhesive compositions comprise 100 parts by weight of a base adhesive resin such as a hot-melt resin or thermosetting resin, 1 to 200 parts by weight of a water-absorbing crosslinked polymer, 1 to 300 parts by weight of heat-expandable particles, and 0.001 to 20 parts by weight of a surfactant.

Description

 Description: Peelable adhesive composition and method for producing the same

 The present invention relates to a release-type adhesive composition (including sealant) whose adhesive strength decreases after water absorption or water absorption heating, and in particular, peeling for bonding a plurality of constituent members to form a predetermined structure. It is a type adhesive composition that exhibits a predetermined adhesive strength before water absorption treatment, but the adhesive force is quickly reduced after water absorption or water absorption heating, and can be easily separated into the original components. The present invention relates to a peelable adhesive composition and a method for producing the same. Background art

 In recent years, the Recycling Law has been enacted, and it has been required to separate and collect each component of a structure joined by an adhesive composition, and to reuse each component. It is also desirable that the labeling masking film or the masking film or the like affixed to the base material with the adhesive composition can be easily peeled off from the base material when the intended use is completed.

 However, the conventional adhesive composition is intended only to strongly adhere each component, label, etc., and is separated into each component as required, or the label, etc., without damaging the base material. It was not easy to peel off.

In view of this, Japanese Patent Application Laid-Open No. 5-173874 discloses an adhesive label in which an acryl-based adhesive layer containing a water-absorbing polymer is formed on a heat-shrinkable sheet. However, the disclosed pressure-sensitive adhesive label had to use a heat-shrinkable sheet as a base material, and was not only complicated in configuration but also expensive and economically disadvantageous. In addition, the water-absorbing polymer is used for adhesives with high cohesion, For example, when simply added to an adhesive composed of a block copolymer, an epoxy resin, or the like, there were cases where the peelability was insufficient.

 Further, Japanese Patent Application Laid-Open No. H11-112748 discloses a releasable adhesive sheet. More specifically, it is composed of a base film and an adhesive layer formed on the base film, and the adhesive layer has 100 parts by weight of the acrylic adhesive. The polyolefin granules are blended in the range of 1 to 25 parts by weight. However, even with such a removable adhesive sheet, it has been difficult to easily and quickly remove the adhesive sheet from the base material after a long period of time.

 On the other hand, since polyolefin granules are used, it is not easy to mix and disperse them uniformly in the acrylic adhesive, and the range of polyolefin granules added must be strictly limited, and the adhesive is bonded from the beginning. There was a problem that defects easily occurred.

In addition, Japanese Patent Application Laid-Open No. Hei 7-118580 discloses a method for peeling an adhesive, affixed or coated article from a substrate using a peeling sheet. More specifically, a release sheet is constituted by a base material and an adhesive layer formed of an anaerobic adhesive or an anaerobic pressure-sensitive adhesive formed thereon. Then, after the release sheet is attached to the surface of an adhesive, affixed or painted material, the adhesive layer is cured to release these adhesives and the like. However, when a long period of time has elapsed, it has been difficult to uniformly peel the adhesive from the substrate even with such a release sheet. Also, when peeling off the adhesive or the like, a process of attaching a peeling sheet and a process of curing are indispensable, and it took a long time before peeling. Japanese Unexamined Patent Publication (Kokai) No. 11-92728 discloses a peelable adhesive composition containing a water-soluble filler in a range of 0.1 to 200 parts by weight based on an adhesive base resin. Has already been proposed. When such a peelable adhesive composition is used, an effect that the structure can be peeled in a short time by immersing the structure can be obtained. However, even in such a peelable adhesive composition, a peelable adhesive composition that can be easily peeled in a shorter time depending on the application. Was desired. Furthermore, when a hot-melt type adhesive is used as the base resin of the adhesive, it is difficult to disperse uniformly when a relatively large amount of a water-soluble filler is added due to its high viscosity. Case was seen.

 Japanese Patent Application Laid-Open Nos. Sho 56-61467, Sho 56-61468, Sho 60-252681, Sho 63-17981, Hei 6-33025, Kaihei 6-184504, JP-A-112-18921, JP-2000-868994, and JP-A-2000-239620 disclose an adhesive or a photocurable resin comprising an acrylic resin or the like. A heat-peelable adhesive to which a predetermined amount of thermally expandable particles is added is disclosed. However, all of these heat-peelable adhesives are intended only for heat-peeling, and are not intended for rapid self-peeling by combining heat-expandable particles with a water-absorbent crosslinked polymer. Did not.

 Therefore, the inventors of the present invention used a hot-melt type adhesive or the like as a base resin of an adhesive by containing a water-absorbent crosslinked polymer and further heat-expandable particles in a predetermined amount range. Even in this case, the inventors have found that an adhesive composition that can be uniformly dispersed and that can be peeled off in a shorter time can be obtained, and the present invention has been completed.

 That is, an object of the present invention is that even when a relatively large amount of a water-absorbent crosslinked polymer is added, the water-absorbent crosslinked polymer can be uniformly dispersed in a base resin of various adhesives, and is high before water absorption. An object of the present invention is to provide an adhesive composition that can obtain adhesive strength and can be peeled off in a short time after absorbing water, and a production method that can efficiently obtain such a peelable adhesive composition.

 Another object of the present invention is to provide a release-type adhesive composition that combines heat-expandable particles and a water-absorbent crosslinked polymer to self-peel (natural release) after water absorption and heating, and such a release. An object of the present invention is to provide a production method capable of efficiently obtaining a mold adhesive composition. Disclosure of the invention

[1] According to the present invention, there is provided a peelable adhesive composition having a reduced adhesive strength after absorbing water. There is provided a peelable adhesive composition containing the water-absorbent crosslinked polymer in the range of 1 to 200 parts by weight with respect to 100 parts by weight of the base resin of the adhesive, and solves the above-mentioned problems. be able to.

 That is, by forming a peelable adhesive composition by combining an adhesive base resin and a predetermined range of a water-absorbing crosslinked polymer, a structural article bonded using such a peelable adhesive composition When a component (different from the component) is immersed in water, etc., the water-absorbent cross-linked polymer swells moderately, the adhesive strength between the components decreases quickly, and each component is separated and collected. Can be.

 When the water-absorbing crosslinked polymer is used and the amount of addition is within such a range, it can be uniformly dispersed in the base resin of the adhesive. The term “after water absorption” in which the adhesive strength is reduced refers to water (which may contain an alcohol or a surfactant, etc .; the same applies hereinafter), hot water (less than 40 to 70 ° C) or It refers to the state of being immersed in hot water (70 to 150 ° C including pressurized conditions) and forcibly absorbing water. Therefore, it does not mean a state in which the water-absorbing crosslinked polymer partially absorbs moisture in the surrounding air.

[2] Further, in constituting the peelable adhesive composition of the present invention, when the water-absorbing bridge polymer is in the form of particles, the average particle diameter is set to a value in the range of 1 to 300 m, When the water-absorbent crosslinked polymer is fibrous, the average fiber length is preferably in the range of 2 to 60 mm.

 By limiting the average particle size of the water-absorbent crosslinked polymer to the average fiber length to such a range, the water-absorbent crosslinked polymer can be more uniformly dispersed in the base resin of the adhesive. Moreover, a water-absorbent crosslinked polymer having such an average particle diameter / average fiber length can effectively prevent problems such as variation or reduction in adhesive strength before water absorption.

 [3] Further, in constituting the peelable adhesive composition of the present invention, it is preferable that the water absorption ratio of the water-absorbing bridge polymer is set to a value within a range of 5 to 1,000 times.

By limiting the water absorption capacity of the water-absorbent crosslinked polymer to such a range, even if a relatively small amount is added, the adhesive force after water absorption can be effectively reduced. Can be.

 [4] Further, in constituting the peelable adhesive composition of the present invention, the water-absorbing bridge polymer is a crosslinked product of a hydrolyzate of a starch-acrylic nitrile graft polymer, and a starch-acrylic acid graft polymer. Crosslinked product of neutralized product of union, crosslinked product of saponified vinyl acetate acrylate copolymer, crosslinked product of hydrolyzed acrylonitrile copolymer, hydrolyzed product of acrylamide copolymer Selected from the group consisting of a crosslinked product of the above, a partially neutralized product of polyacrylic acid, a crosslinked product of a carboxyl group-containing crosslinked polyvinyl alcohol, a crosslinked isobutylene-maleic anhydride copolymer, a polyethyleneoxide crosslinked product, and a crosslinked urethane modified product It is preferably at least one of the following.

 With such a kind of water-absorbing crosslinked polymer, even if it is added in a relatively small amount, the adhesive force after water absorption can be effectively reduced.

 In addition, such a water-absorbing crosslinked polymer can be more uniformly dispersed in the base resin of the adhesive.

 [5] Further, in constituting the peelable adhesive composition of the present invention, the surfactant is added in the range of 0.001 to 20 parts by weight with respect to 100 parts by weight of the base resin of the adhesive. It is preferred to include.

 By adding a surfactant in such a range, the adhesive strength after water absorption can be reduced more efficiently, and self-peeling becomes possible depending on the added amount.

 [6] Further, in forming the peelable adhesive composition of the present invention, the base resin of the adhesive is a rubber-based resin, and the tackifier is added to 100 parts by weight of the base resin of the adhesive. Is preferably contained in the range of 1 to 800 parts by weight. By using a base resin and a tackifier of such an adhesive, it is possible to effectively provide a peelable adhesive composition having a high initial adhesive strength, but having a significantly reduced adhesive strength after water absorption. Can be.

 [7] Further, in constituting the peelable adhesive composition of the present invention, it is preferable that the base resin of the adhesive is a hot melt type resin.

Thus, as a base resin for the adhesive, a hot-melt resin such as S 02 0

6

 By using a BS block copolymer or a SIS block copolymer, it is possible to more effectively mix and disperse the base resin of the adhesive and the water-absorbent crosslinked polymer.

 In other words, a hot-melt resin can be adjusted to an appropriate viscosity simply by heating without using a solvent, so that it can be uniformly mixed and dispersed without deteriorating the water-absorbent crosslinked polymer. Can be.

 [8] Further, in constituting the peelable adhesive composition of the present invention, it is preferable that the base resin of the adhesive is a thermosetting resin.

 By using such a thermosetting resin, the initial adhesive strength is high, and excellent mechanical properties and heat resistance can be obtained, so that it can be used as a structural adhesive.

 The thermosetting resin has a low molecular weight before curing and has a relatively low viscosity, so that it can be easily handled as an adhesive.

 [9] Further, in constituting the peelable adhesive composition of the present invention, the thermally expandable particles are contained in an amount of 1 to 300 parts by weight based on 100 parts by weight of the base resin of the adhesive. Is preferred.

 By combining the heat-expandable particles in this way, when hot water or steam is used, the water-absorbent cross-linked polymer absorbs water and the heat-expandable particles also expand, so they are separated from the adherend in a very short time. Depending on the amount of addition, self-peeling can also be performed.

 [10] Another embodiment of the present invention relates to a method for producing a peelable adhesive composition in which the adhesive strength is reduced after water absorption,

 A step of preparing a base resin of the adhesive in a molten state,

 With respect to 100 parts by weight of the base resin of the adhesive, a water-absorbent crosslinked polymer having an average particle diameter of 1 to 800 m and a water-absorbent crosslinked polymer having an average fiber length of 2 to 60 mm, or A dry blending step of adding one of the water-absorbent crosslinked polymers in a range of 1 to 200 parts by weight,

It is a manufacturing method of the peelable adhesive composition characterized by containing. Thus, a release adhesive composition can be produced using the adhesive in a molten state. Accordingly, the water-absorbing crosslinked polymer can be uniformly dispersed in the base resin of the adhesive even without solvent. Therefore, a high adhesive strength can be obtained before water absorption, while a water-absorbent cross-linked polymer swells moderately after water absorption, and a peelable adhesive composition in which the adhesive force quickly decreases can be effectively obtained. .

[11] Another aspect of the present invention is a method for producing a peelable adhesive composition in which the adhesive strength is reduced after water absorption,

 A step of preparing a thermosetting resin as a base resin of the adhesive; and adding 1 to 200 parts by weight of a water-absorbing crosslinked polymer to 100 parts by weight of the base resin of the adhesive. Process and

 It is a manufacturing method of the adhesive composition characterized by containing.

 By producing a peelable adhesive composition using a thermosetting resin in this way, it is possible to uniformly disperse the water-absorbent crosslinked polymer even in the absence of a solvent in the base resin of the adhesive. it can. Accordingly, it is possible to obtain an extremely high adhesive strength before water absorption, but it is possible to effectively obtain a peelable adhesive composition in which, after water absorption, the water-absorbent crosslinked polymer swells appropriately and the adhesive strength decreases promptly. it can.

[12] In carrying out the method for producing the peelable adhesive composition of the present invention, the heat-expandable particles are added in an amount of 1 to 300 parts by weight based on 100 parts by weight of the base resin of the adhesive. It is preferable to further include a step of adding in a range of parts by weight.

 When implemented in this manner, a peelable adhesive composition that can be peeled from an adherend in an extremely short time can be effectively obtained using hot water, steam, or the like. BRIEF DESCRIPTION OF THE FIGURES

 FIG. 1 is a diagram showing an example of the effect of the amount of water-absorbent crosslinked polymer added.

 FIG. 2 is a diagram showing an example of a change in adhesive force under different water absorption conditions. FIG. 3 is a diagram showing an example of the effect of the amount of the thermally expandable particles added.

FIG. 4 is a cross-sectional view of a film adhesive made of the heat-adhesive peelable adhesive composition of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION [First Embodiment]

 A first embodiment of the present invention is a release adhesive composition containing the following components (A) to (D) (hereinafter sometimes referred to as a water release adhesive composition). In addition, in such a water-peelable adhesive composition, the components (A) and (B) are essential components, and the components (C) and (D) are optional components.

 (A) Base resin of adhesive: 100 parts by weight

 (B) Water-absorbing crosslinked polymer: 1 to 200 parts by weight

 (C) Tackifier: 1 to 800 parts by weight

 (D) Surfactant: 0.001 to 20 parts by weight

1. adhesive base resin

 The base resin of the adhesive used in the present invention includes a hot melt adhesive, a solvent-based adhesive, a photo-curable adhesive, a one-part type thermosetting adhesive, and a two-part type thermosetting adhesive. Adhesives such as adhesives and pressure-sensitive adhesives (adhesives) can be used. For example, hot-melt adhesives, organic solvent-based adhesives, or pressure-sensitive adhesives (adhesives) include (meth) acrylic acid-based polymers, polyvinyl chloride resins, polyurethane resins, cellulose acetate resins, Ethylene vinyl acetate copolymer, polyvinyl acetate resin, olefin resin, polyvinyl acetal resin, polyvinyl alcohol derivative, silicone resin, natural rubber, acryl rubber, chloroprene rubber, nitrile rubber, butadiene rubber, butyl rubber, acrylic Nitrile butadiene rubber (NBR), ethylene vinyl acetate copolymer (EVA) resin, styrene-butadiene-styrene (SBS) block copolymer, styrene-isoprene-styrene (SIS) block copolymer, styrene Ethylenebutylene-styrene (S EBS) block Polymers, polyester resins, phenoxy resins, Porisarufai de resin.

Epoxy resins, oxetane resins, reactive acrylic resins (SGA), silicone resins, urethane resins, polyester resins, cyanoacrylate adhesives are also used as photo-curing adhesives and thermosetting adhesives. , I Examples include an aldehyde adhesive, a melamine aldehyde adhesive, and a urea aldehyde adhesive.

 In particular, when an epoxy resin is used, it is preferable to use a bisphenol A-type epoxy resin, an alicyclic epoxy resin, or the like as a main agent, and to use a combination of polyamine dimidazole or the like as a curing agent. When a reactive acrylic resin is used, it is preferable to use a combination of an acryl monomer and a radical generator as a main component, and to use a combination of an acryl monomer and a reducing agent as a curing accelerator.

2. Crosslinked polymer

 (1) Type

 The type of the water-absorbent crosslinked polymer is not particularly limited as long as it is particles or fibers obtained by reacting the water-absorbent resin with a crosslinking agent. It is preferable to use a starch-based resin, a polyacrylic acid-based resin, a polyvinyl alcohol-based resin, a polyacrylamide-based resin, and a polyoxymethylene-based resin.

 Accordingly, such water-absorbent crosslinked resins include, for example, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, iS-hydroxyacrylic acid, It is preferably a crosslinked resin obtained by polymerizing at least one monomer component selected from β-acryloxypropionic acid and a neutralized product thereof together with a crosslinking agent.

 Preferred crosslinking agents include, for example,

i) Ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate,

Compounds having two or more ethylenically unsaturated groups in one molecule, such as N, Ν'-methylenebis (meth) acrylamide;

i Diethylene glycol, diethylene glycol, glycerin, propylene glycol, 1,4-butanediol, polypropylene glycol, etc. Polyhydric alcohol;

i i i) Polyglycinolone such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin triglycidyl ether;

i v) Haloepoxy compounds such as epichlorohydrin and monomethylchlorohydrin;

 V) Polyaldehydes such as Daltar aldehyde and Glioxal; v i) Polyamines such as ethylenediamine;

v i i) polyvalent isocyanate compound, polyvalent epoxy compound, polyvalent aziridine compound;

And the like, alone or in combination of two or more.

 The amount of the cross-linking agent used is preferably determined in consideration of the amount of water absorption in the water-absorbent cross-linked polymer.

Against 0 0 mol%, 0.0 0 5-2 mole ⁰ / o value that it is good Mashiku in the range, 0.0 1 to a value within the range between 1 mol _^0/0 Is more preferred. It is also preferable to polymerize an uncrosslinked water-absorbing resin in advance without using a crosslinking agent, and then add a crosslinking agent to cause a reaction to obtain a water-absorbing crosslinked polymer.

 Therefore, preferred water-absorbent crosslinked polymers include a crosslinked product of a hydrolyzate of a starch-acrylonitrile graft polymer, a crosslinked product of a neutralized product of a starch-acrylic acid graft polymer, and a vinyl acetate-acrylic acid ester copolymer Cross-linked saponified product, cross-linked hydrolyzate of acrylonitrile copolymer, cross-linked hydrolyzate of acrylamide copolymer, partially neutralized cross-linked polyacrylic acid, containing carboxyl group Examples include cross-linked polyvinyl alcohol modified products, cross-linked isobutylene-maleic anhydride copolymers, cross-linked polyethylene oxide products, cross-linked urethane modified products, and the like.

 With these water-absorbing crosslinked polymers, excellent water absorption can be obtained, and the addition of a relatively small amount can effectively prevent a decrease in adhesive strength.

(2) Water absorption ratio Further, the water absorption ratio of the water-absorbing resin is preferably set to a value within a range of 5 to 1,000 times.

 The reason for this is that if the water absorption ratio is less than 5 times, the adhesive strength after water absorption may not be sufficiently reduced, or it may be necessary to add a large amount of water absorbent resin. It is.

 However, if the water absorption ratio of the water-absorbent resin is excessively large, the initial adhesive strength will decrease if the surrounding water is absorbed before the adhesive composition is absorbed and added to the base resin of the adhesive. May be. Therefore, the water absorption capacity of the water-absorbent resin is more preferably set to a value in the range of 10 to 500 times, and further preferably to a value in the range of 50 to 300 times.

 The water absorption capacity of the water-absorbent resin can be measured as a volume increase ratio after immersing the water-absorbent resin in excess water for 24 hours.

 (4) Average particle size and average fiber length

Further, it is preferable that a value within the range of average particle diameter of the water-absorbent crosslinked polymer of from 0.1 to 8 0 0 0 _1.

 The reason for this is that if the average particle size of the water-absorbent crosslinked polymer is less than 0.1, it may be difficult to uniformly mix and disperse, or the adhesive force after water absorption may not be sufficiently reduced. Because there is.

 On the other hand, when the average particle size of the water-absorbent crosslinked polymer exceeds 800 m, it becomes difficult to uniformly mix and disperse the resin in the base resin of the adhesive, or the initial adhesive strength decreases. This is because there are cases where

 Therefore, it is more preferable to set the average particle diameter of the water-absorbent crosslinked polymer to a value in the range of 0.5 to 500 <m, and to a value in the range of 10 to "! Is more preferable.

 When the water-absorbent crosslinked polymer is fibrous, the average fiber length is preferably in the range of 2 to 6 Omm.

The reason for this is that if the average fiber length of the water-absorbent crosslinked polymer is less than 2 mm, it may be difficult to mix and disperse it uniformly, or the adhesive strength after water absorption may not be sufficiently reduced. Because there is. Meanwhile, such water absorption If the average fiber length of the cross-linked polymer exceeds 6 Omm, it may be difficult to mix and disperse it uniformly in the base resin of the adhesive, or the initial adhesive strength may decrease. That's why.

 Accordingly, the average fiber length of the water-absorbent crosslinked polymer is more preferably set to a value in the range of 3 to 5 Omm, and further preferably to a value in the range of 5 to 40 mm.

 The average particle size / average fiber length of the water-absorbent crosslinked polymer can be determined by actually measuring the particle size / fiber length from an electron micrograph and calculating the average value from the measured value.

 However, the shape of the water-absorbent crosslinked polymer is not limited to a particle shape or a fibrous shape, and may be a polygon, an irregular shape, or a combination thereof.

(5) Addition amount

 Further, the amount of the water-absorbing crosslinked polymer to be added is preferably set to a value within the range of 1 to 200 parts by weight based on 100 parts by weight of the base resin of the adhesive.

 The reason for this is that if the amount of the water-absorbing crosslinked polymer added is 1 part by weight, the decrease in adhesive strength after water absorption may be insufficient. On the other hand, if the added amount of the water-absorbent crosslinked polymer exceeds 200 parts by weight, it may be difficult to reduce the initial adhesive strength or to uniformly mix and disperse. Devil.

Therefore, it is more preferable that the amount of the water-absorbing cross-linked polymer is in the range of 100 to 100 parts by weight with respect to 100 parts by weight of the base resin of the adhesive. More preferably, the value is in the range of up to 80 parts by _weight.c Here, an example of the effect of the amount of the water-absorbing crosslinked polymer on the adhesive force will be described with reference to FIG. In Fig. 1, the horizontal axis shows the amount (parts by weight) of the water-absorbent cross-linked polymer with respect to 100 parts by weight of the adhesive base resin, and the vertical axis shows the adhesive force (MPa). Is shown. Line A changes the amount of the water-absorbing crosslinked polymer added in the surfactant-free formulation of Example 1. Line A 'shows the adhesion after immersion in warm water (60 ° C) for 6 hours. Line B shows the initial adhesive force measured by changing the amount of the water-absorbent crosslinked polymer in the formulation containing a predetermined amount of the surfactant of Example 1, and line B 'shows hot water (60%). (° C) for 6 hours.

 As can be easily understood from the change curves in FIG. 1, although the addition amount of the water-absorbent crosslinked polymer hardly affects the initial adhesive strength of both lines A and B, the addition amount of the water-absorbent crosslinked polymer, for example, When the amount exceeds 25 parts by weight, the adhesive strength after immersion in hot water (60 ° C) for 6 hours is remarkably reduced as compared with the initial adhesive strength. The tendency of the adhesive strength to decrease is more remarkable in the line B ′ containing a surfactant.

 Therefore, as an example, in an adhesive composition containing a predetermined amount of a surfactant, the addition amount of the water-absorbing cross-linked polymer is set to a value of 10 parts by weight or more, and an adhesive composition containing no surfactant is used. In, by setting the amount of the water-absorbing cross-linked polymer to a value of 30 parts by weight or more, it is possible to sufficiently reduce the adhesive strength after water absorption.

 It is known that the adhesive force change curve shown in FIG. 1 varies not only with the type of the adhesive base resin but also with the type of the water-absorbing cross-linked polymer and tackifier. .

 (6) Surface treatment

 In addition, when the water-absorbent crosslinked polymer is added to the base resin of the adhesive, it is preferable to heat and melt the base resin. For this reason, due to such heat melting, the water-absorbent crosslinked polymer may be thermally decomposed or aggregated, making it difficult to uniformly mix and disperse the water-absorbent crosslinked polymer. Therefore, it is preferable to improve the heat resistance and the mixing and dispersibility in advance by performing a surface treatment on the water-absorbent crosslinked polymer.

Specifically, the surface of the water-absorbent crosslinked polymer is treated with a coupling agent, added with inorganic particles, metal plating, metal deposition, inorganic deposition, or a polymer having a higher glass transition point than the water-absorbent crosslinked polymer. It is preferable to use and coat. (F) Other

 In addition, in the water-absorbent crosslinked polymer, a thixotropy agent, a viscosity modifier, a plasticizer, a coloring agent, a pigment, a weathering agent, an ultraviolet absorber, a discoloration inhibitor, an oxidation agent may be contained within a range not departing from the object of the present invention. It is also preferable to add one kind or a combination of two or more kinds of inhibitors, inorganic particles, carbon particles, carbon fibers, conductive particles, extenders, fungicides, antibacterial agents, and bactericides.

 In particular, it is preferable to add an antioxidant, inorganic particles, carbon particles, carbon fibers, conductive particles, or the like, since the heat resistance of the water-absorbent crosslinked polymer can be improved. In other words, even when added to the heated base resin in the molten state, it is possible to effectively prevent the water-absorbent crosslinked polymer from being thermally decomposed or aggregated due to such heating. .

3. Tackifier

 (1) Type

 The tackifier is added to improve the initial adhesive strength and to effectively reduce the adhesive strength when absorbing water. Further, by adding a tackifier, a function as a dispersant can be exhibited when the water-absorbing crosslinked polymer is added to the base resin of the adhesive.

 The type of such a tackifier is preferably determined in consideration of the adhesive strength when water is absorbed. Specifically, aliphatic petroleum resins, aromatic petroleum resins, and aliphatic and aromatic Polymerized petroleum resin, alicyclic hydrogenated petroleum resin, alkyl phenol resin, xylene resin, coumarone indene resin, terpene resin, terpene; c-nor resin, aromatic modified terpene resin, hydrogenated terpene resin, rosin resin, One type of hydrogenated rosin-based resin, disproportionated rosin-based resin, dimerized rosin-based resin, esterified rosin-based resin and the like may be used alone or in combination of two or more.

In addition, among these tackifiers, it is particularly preferable to use an aliphatic petroleum resin or an aromatic petroleum resin. The reason for this is that by using such a tackifier, the addition of a small amount can effectively improve the adhesive force when absorbing water. This is because such a tackifier is economical and economical.

 (2) Addition amount

 Further, the amount of the tackifier to be added is preferably in the range of 1 to 800 parts by weight per 100 parts by weight of the base resin of the adhesive.

 The reason for this is that if the amount of the tackifier is less than 1 part by weight, the adhesive strength after water absorption may not be sufficiently reduced, or the initial adhesive strength may be reduced. On the other hand, if the added amount of the tackifier exceeds 800 parts by weight, it becomes difficult to uniformly mix and disperse the adhesive in the base resin, or the creep resistance of the obtained adhesive becomes poor. This is because it may decrease.

 Therefore, the amount of the tackifier is more preferably in the range of 5 to 500 parts by weight, and even more preferably in the range of 30 to 300 parts by weight.

4. Surfactant

 (1) Type

 Surfactants are preferably used when rapidly absorbing water to reduce the adhesive strength, but the type thereof is not particularly limited. Anionic surfactants, cationic surfactants, and nonionic surfactants are used. Any of a surfactant and a polymer surfactant may be used.

 Specifically, one or two or more of fatty acids, fatty acid esters, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, sorbitol fatty acid esters, sorbitan fatty acid ester ethers, sorbitol fatty acid ester ethers, glycerin fatty acid esters, sucrose fatty acid esters, etc. Combinations of more than one species are included.

In particular, polyethylene glycol monostearyl ether, decaglycerin tristearyl ester, sorby! ^ One monostearate, Sorbi! ^ 1 Lumonolaurelat, Sorbitan monostearate, Sorbitan monolau The use of relay, sucrose distearate, sucrose monodistearate, etc. can significantly reduce the adhesive strength after water absorption with a small amount of addition, while effectively reducing the initial adhesive strength. It is preferable because it can be prevented.

 (2) Addition amount

 Further, the amount of the surfactant added is preferably set to a value within the range of 0.001 to 20 parts by weight based on 100 parts by weight of the base resin.

 The reason for this is that if the amount of the surfactant is less than 0.001 parts by weight, the effect of addition is not exhibited, and when the adhesive composition absorbs water, the adhesive force is rapidly reduced. This is because it may not decrease. On the other hand, if the amount of the surfactant exceeds 20 parts by weight, it may be difficult to uniformly mix and disperse the surfactant, or the initial adhesive strength may decrease.

 Therefore, the amount of the surfactant added is more preferably set to a value within the range of 0.5 to 10 parts by weight, and even more preferably set to a value within the range of 1 to 5 parts by weight.

5. Additives

 (1) Water-soluble filler

 It is also preferable to add a water-soluble filler together with the water-absorbent crosslinked polymer described above. By adding such a water-soluble filler, the adhesive strength after water absorption can be more effectively reduced.

 Examples of such a water-soluble filler include inorganic salts, chelates, polysaccharides, urine resins, sodium bicarbonate, etc., alone or in combination of two or more. When such a water-soluble filler is added, the amount of the water-soluble filler should be within a range of 5 to 50 parts by weight per 100 parts by weight of the base resin of the adhesive. Is preferred.

 (2) Coupling agent

Preferably, at least one force coupling agent selected from the group consisting of a silane coupling agent, an aluminum force coupling agent, and a titanium coupling agent is added to the base resin of the adhesive. The reason for this. By adding such a coupling agent, before immersion in water, it is possible to prevent the adhesive strength from being reduced by moisture in the air or the like. This is because it can be configured so as not to prevent the adhesive force from rapidly decreasing.

 Specific examples of such coupling agents include r-aminopropyltriethoxysilane, τ-glycidoxypropyltrimethoxysilane, r-mercaptopropyltriethoxysilane, r-aminopropyltriethoxyaluminum, and r-aminopropyltriethoxysilane. Aminopropyltrimethoxytitanium and the like can be mentioned.

 When the coupling agent is added, the amount of the coupling agent is preferably set to a value within the range of 0.1 to 20 parts by weight per 100 parts by weight of the base resin of the adhesive. The value is more preferably in the range of 5 to 10 parts by weight, and even more preferably in the range of 1 to 5 parts by weight.

(3) Organic solvent

 When a solution type adhesive is used, it is also preferable to add an appropriate organic solvent.

 Such organic solvents include methyl ethyl ketone, methyl isobutyl ketone, toluene, ethyl ether, ethyl acetate, tetrahydrofuran,

N.N-Dimethylformamide, methanol, 1-butanol, etc. may be used alone or in combination of two or more.

 (4) Other

 Also, in the base resin of the adhesive, the same additives as the additives to the water-absorbing cross-linked polymer, for example, thixotropic agents, viscosity modifiers, plasticizers, coloring agents, pigments, weathering agents, discoloration inhibitors, curing It is also preferable to add one kind or a combination of two or more kinds of agents, antioxidants, inorganic particles, carbon particles, carbon fibers, conductive particles and the like within a range not departing from the object of the present invention.

6. Manufacturing method

Although the method for producing the water-peelable adhesive composition is not particularly limited, For example, it is preferable to include the following steps.

 (A) Step of preparing base resin of adhesive in molten state

 (B) A water-absorbent crosslinked polymer having an average particle diameter of 1 to 800 μm and a water-absorbent crosslinked polymer having an average fiber length of 2 to 6 Omm, based on 100 parts by weight of the base resin of the adhesive. Or one of the two water-absorbent crosslinked polymers is added in an amount of 1 to 200 parts by weight.

(1) Step of preparing base resin of adhesive in molten state

 This is a step of heating the base resin of the adhesive to a molten state. Therefore, as the base resin of the adhesive, it is preferable to use a thermoplastic resin such as a SISS block copolymer or a SBS block copolymer because of easy handling.

 However, even when a thermosetting resin is used, a molten adhesive can be used by using a latent curing adhesive or by using a two-pack adhesive consisting of a main agent and a curing agent. For example, when using a thermosetting epoxy adhesive composed of a bisphenol A resin and an amine-based curing agent, only the bisphenol A resin is heated and melted. The amine-based curing agent is preferably added at the time of use after the dry blending step or the dry blending step.

 (2) Dry blending process

① Mixing ratio

 _ The mixing ratio of the water-absorbing crosslinked polymer is preferably set to a value within the range of 1 to 200 parts by weight, based on 100 parts by weight of the base resin of the adhesive in a molten state, and 100 to 1 part by weight. The value is more preferably in the range of 100 parts by weight, and even more preferably in the range of 20 to 80 parts by weight.

The reason for this is that, as described above in part, when the mixing ratio is less than 1 part by weight, the mixing and dispersing itself is easy, but the adhesive strength of the obtained water-peelable adhesive composition after water absorption decreases. Is sometimes insufficient. JP01 / 08511

19

On the other hand, if the amount of the water-absorbent crosslinked polymer exceeds 200 parts by weight, it may be difficult to uniformly mix and disperse the polymer.

 ② Mixing temperature

 Further, the temperature at which the water-absorbent crosslinked polymer or the like is mixed into the base resin of the adhesive, that is, the temperature of the base resin of the adhesive may be set to a value within a range of 100 to 250 ° C. preferable. The reason for this is that if the mixing temperature is lower than 100 ° C., it may be difficult to uniformly mix and disperse the water-absorbent crosslinked polymer. If the temperature exceeds ° C, the water-absorbent crosslinked polymer may be thermally decomposed or aggregated.

 Therefore, the mixing temperature of the water-absorbent crosslinked polymer is more preferably set to a value in the range of 120 to 200 ° C, and more preferably to a value in the range of 150 to 180 ° C. Is more preferred.

 ③Mixing machine

 The mixer for mixing the water-absorbent crosslinked polymer and the like into the base resin of the adhesive is not particularly limited. For example, a cylindrical mixer, a double-walled conical mixer, and a high-speed mixer Type mixer, V-shaped mixer, Ripon-type mixer, screw-type mixer, fluid-type furnace rotary desk-type mixer, air-flow type mixer, double-arm type kneader, internal mixer, pulverization type kneader, rotary mixing It is preferable to use an extruder or a screw type extruder.

 ④ Organic solvent

 When mixing the water-absorbent crosslinked polymer into the base resin of the adhesive, it is preferable to dry blend without using an aqueous solvent so that the water-absorbent crosslinked polymer does not swell. However, it is also preferable to use an organic solvent as long as the water-absorbent crosslinked polymer does not excessively swell.

7. How to use

 (1) Coating method

When bonding the components using the water-peelable adhesive composition of the present invention, a well-known adhesive application means, for example, a roll coater, a bar coater, a brush coating It is preferable to apply the adhesive composition by a spatula or a spatula.

 In addition, when the water-peelable adhesive composition is a solution-based adhesive or a one-part adhesive, it is preferable to use a dispenser, and in the case of a hot-melt adhesive, an applicator is used. Is preferred.

 In addition, when immersed in water, the adhesive strength of the water-peelable adhesive composition is not prevented from decreasing, but the adhesive strength is not decreased by moisture in the air or the like. Since it is possible to further improve the initial adhesive strength, it is preferable to apply a silane coupling agent to the coated surface of the adhesive with a primer.

 (2) Form

 The form of the water-peelable adhesive composition of the present invention is not particularly limited, and examples thereof include hot melt adhesives, film adhesives, solvent adhesives, and spray adhesives. And other various forms. In addition, the water-peelable adhesive composition of the present invention is laminated on a substrate, and is formed into a form such as an adhesive tape, a masking tape (coating tape), a marking film, a temporary fixing tape, a plating tape, and a process tape. It is also preferable that In this case, it is preferable that a polyester film, a vinyl chloride film, a polypropylene film, a fluororesin film, or the like is used as a base material, and an adhesive layer having a thickness of 100 to 500 im is formed thereon. .

 (3) Peeling conditions!

The peeling conditions for peeling the water-peelable adhesive composition are not particularly limited as long as the water-absorbing adhesive composition reduces the adhesive strength by absorbing water. Soak in water at 10 ° C (including hot water under pressurized conditions; the same applies hereinafter) for 10 minutes to 24 hours, or add water at 10 ° C to 150 ° C for 1 minute. It is preferable to shower from 0 minutes to 24 hours. The reason for this is that under such a water absorbing condition, such as a simple condition, water, hot water or hot water can be used as it is, and if such a water absorbing time or a showering time is used, the adherend can be effectively used. Can be decomposed. However, in order to more quickly lower the adhesive strength, alcohol or a surfactant (including a dispersant and a detergent) is added to water 10. It is also preferable to add 0.1 to 20 parts by weight of water per 0 parts by weight. On the other hand, as the peeling liquid, it is preferable to use a fluorine-based / silicone-based inert liquid instead of the above-mentioned water, hot water or hot water, and in addition to the above-mentioned water, hot water or hot water.

 Here, with reference to FIG. 2, an example of a change in adhesive force due to a difference in water absorption conditions is shown. As an adhesive, for example, an adhesive having the composition shown in Example 3 was prepared, and was set to each condition of 25 ° C × 80% RH, water (25 ° C), 60 ° C hot water, and 90 ° C hot water. It shows a change in adhesive strength when left for a long time. As can be easily understood from Fig. 2, when water is not absorbed basically (25 ° C x 80% RH), the adhesive force is hardly changed, but the more it is immersed in high-temperature hot water or hot water. The decline is significant. Therefore, it is possible to set a desired stripping time by adjusting the temperature of the water.

 (4) Peeling condition 2

Further, it is preferable that pressure is applied when the water-peelable adhesive composition is peeled off ₍ the reason is that the pressure increases the water-absorbing frame polymer in the water-peelable adhesive composition more rapidly. Therefore, it is preferable that the surrounding pressure is set to a value in the range of 0 to 1 MPa (about 1 to 10 atm), It is more preferable that the value be in the range of 0 to 0.5 MPa (about 1 to 5 atm), and it is preferable that the value be in the range of 0.1 to 0.3 MPa (about 1 to 3 atm). More preferred.

[Second embodiment]

The second embodiment of the present invention is a release adhesive composition containing the following components (A) to (E) (hereinafter sometimes referred to as a combined heat release adhesive composition). It is characterized by adding (B) a water-absorbent crosslinked polymer and (E) thermally expandable particles to (A) a base resin of an adhesive. Therefore, the components (A), (B) and (E) are essential components, and the components (C) and (D) are optional components in the hot-release adhesive composition of the second embodiment. is there. The contents of the components (A) to (D) are the same as in the first embodiment. The description can be omitted here.

 (A) Base resin of adhesive: 100 parts by weight

 (B) Water-absorbing crosslinked polymer: 1 to 200 parts by weight

 (C) Tackifier: 1 to 800 parts by weight

 (D) Surfactant: 0.000 "! ~ 20 parts by weight

 (E) Thermal expansive particles: "! ~ 300 parts by weight

1. Types of thermally expandable particles

 The heat-expandable particles can be suitably used as long as the particles increase in volume upon heating. For example, the outer shell is a vinylidene chloride-acrylonitrile copolymer resin or vinyl acetate. It is composed of one type or a combination of two or more types of luacrylonitrile copolymer resin, methyl methacrylate-acrylonitrile copolymer resin, acrylonitrile resin, phenolic resin, epoxy resin, etc. It is preferable that the inside contains a heat-foamable gas or liquid.

 Further, it is preferable that the average particle size of the thermally expandable particles be a value within a range of 1 to 300 m. The reason for this is that if the average particle size of the thermally expandable particles is less than 1 jwm, the releasability of the adhesive may decrease. On the other hand, if the average particle size of the thermally expandable particles exceeds 300 jum, it may be difficult to uniformly mix the adhesive into the base resin. Therefore, the average particle diameter of the thermally expandable particles is more preferably set to a value within a range of 3 to 200 Um, and even more preferably to a value within a range of 5 to 150 jUm. Better. The average particle size of the hollow microspheres can be easily calculated from an optical micrograph using an image processing device.

2. Addition amount of thermally expandable particles

It is preferable that the amount of the heat-expandable particles is in the range of 1 to 300 parts by weight based on 100 parts by weight of the base resin of the adhesive. The reason for this is that if the amount of such thermally expandable particles is less than 1 part by weight, the effect of adding This is because the peelability of the adhesive may decrease. On the other hand, if the amount of the heat-expandable particles exceeds 300 parts by weight, the adhesive strength before peeling is reduced, or it is difficult to uniformly mix the adhesive into the base resin. This is because it may be. Therefore, the amount of the heat-expandable particles is more preferably set to a value within the range of 10 to 150 parts by weight, based on 100 parts by weight of the base resin of the adhesive, and 30 to 1 part by weight. More preferably, the value is in the range of 100 parts by weight.

 It is also preferable to determine the amount of the heat-expandable particles to be added in consideration of the peeling conditions described later. For example, in order to prevent self-exfoliation only by heat treatment at 105 ° C or more, the amount of the heat-expandable particles should be adjusted based on 100 parts by weight of the adhesive base resin. It is preferred that the value be in the range of 1 to 40 parts by weight. Also, in order to adjust so as not to be self-peeled only by a heat treatment at 120 ° C. or more, the amount of the heat-expandable particles should be 1 to 3 with respect to 100 parts by weight of the base resin of the adhesive. The value is preferably within the range of 0 parts by weight.

 On the other hand, in order to enable self-peeling at a temperature of more than 105 ° C and a heat treatment time of about 15 to 30 minutes, the amount of the heat-expandable particles must be added to the base resin of the adhesive. It is preferable that the value be in the range of 45 to 100 parts by weight with respect to 100 parts by weight of the fat. Further, in order to be able to self-peel at a temperature of 105 ° C. or more and a heat treatment time of 15 minutes or less, the amount of the heat-expandable particles must be adjusted by adding 100 parts by weight of the base resin of the adhesive. On the other hand, the value is preferably in the range of more than 100 parts by weight to 300 parts by weight.

Here, an example of the effect of the amount of the thermally expandable particles on the adhesive force will be described with reference to FIG. The abscissa indicates the amount (parts by weight) of the heat-expandable particles added to 100 parts by weight of the base resin of the adhesive, and the ordinate indicates the adhesive force (MPa). The left axis shows the self-peeling time (immersion in hot water at 90 ° C) measured by changing the amount of the thermally expandable particles in the adhesive composition of Example 14; Shows the initial adhesive strength. As can be easily understood from FIG. 3, the amount of the thermally expandable particles hardly affects the initial adhesive strength, but when the amount of the thermally expandable particles exceeds, for example, 20 parts by weight. The self-peeling time is significantly shorter. Therefore, as an example, the self-peeling time (immersion in hot water at 90 ° C) can be shortened to within 10 hours by setting the amount of the thermally expandable particles to a value of 25 parts by weight or more. It is possible to It is known that the change curve of the self-peeling time shown in FIG. 3 changes depending on not only the type of the base resin of the adhesive but also the type of the water-absorbing crosslinked polymer.

3. How to use

 (1) Coating method and form

 The coating method and the form of the peelable adhesive composition combined with heat of the second embodiment can be the same as those of the first embodiment, and within a predetermined range, for example, as shown in FIG. As shown, it is also possible to change the form of the combined heat and release adhesive composition.

 Here, FIG. 4 (a) shows that the heat-releasing adhesive composition contains a film-forming resin and the thickness of the heat-releasing adhesive composition is, for example, in the range of 10 to 200 m. It is an example in which the value is set to the value within the range. In addition, FIG. 4 (b) shows that one side (B side in the figure) of the film-form and heat-peelable adhesive composition (sometimes referred to as a first adhesive layer) has organic thermally expandable particles on one side. And an adhesive layer comprising a thermosetting adhesive component containing no organic heat-expandable particles and a water-absorbent cross-linked polymer in a smaller amount than the first adhesive layer. This may be referred to as a second adhesive layer.).

 In addition, FIG. 4 (c) shows whether the organic heat-expandable particles and the water-absorbent cross-linked polymer are not contained between the two heat-peelable adhesive compositions (first adhesive layer), or An adhesive layer composed of a thermosetting adhesive component containing a smaller amount of organic heat-expandable particles and a water-absorbing bridging polymer than the first adhesive layer (may be referred to as a third adhesive layer). This is an example in which is provided.

(2) Peeling conditions

The peeling conditions can be the same as those in the first embodiment. However, the use of hot water with additional heating conditions makes it possible to more quickly exfoliate using the expansion of the thermally expandable particles. Therefore, for example, when 1 to 40 parts by weight of the heat-expandable particles are added to 100 parts by weight of the base resin of the adhesive, self-peeling when simply heated at a temperature of 105 ° C or more is prevented. On the other hand, by using hot water of 70 ° C to 150 ° C including the pressurized condition, self-peeling can be performed within an immersion time of 12 hours or less. In addition, when a predetermined amount of surfactant is further added, self-exfoliation does not occur even when simply heated at a temperature of 105 ° C or more, while using hot water at 70 ° C to 150 ° C increases Self-peeling is possible within a dipping time of less than c

4. Manufacturing method

 The method for producing the heat-release adhesive composition is not particularly limited, but preferably includes, for example, the following steps.

 (A) Step of preparing thermosetting resin as base resin for adhesive

 (B) a step of adding a water-absorbing crosslinked polymer in an amount of 1 to 200 parts by weight based on 100 parts by weight of the base resin of the adhesive;

 (C) a step of adding the heat-expandable particles in a range of 1 to 300 parts by weight

(1) Step of preparing thermosetting resin

As a thermosetting resin, for example, an epoxy resin is prepared, but it is preferable to sufficiently deaerate the adhesive so that the adhesive strength does not vary. In order to adjust the viscosity of the thermosetting resin, it is preferable to add a reactive diluent or a solvent. In that case, the viscosity of the thermosetting resin, for example, 1 00~ 1 00, 00 Om P a ■ s is preferably set to a value within the range of (measurement temperature 25 ° C) _(Further, the thermosetting resin In the preparation stage, it is also preferable to add various particles and fibers, or additives such as antioxidants and coloring agents.

 (2) Step of adding a water-absorbing crosslinked polymer

This is a step of uniformly adding a predetermined amount of a water-absorbent crosslinked polymer to a thermosetting resin as a base resin of the adhesive. And when using thermosetting resin. Due to the relatively low viscosity, it is not necessary to dry blend the water-absorbing cross-linked polymer with the adhesive resin heated to a molten state. It is also preferable to do so.

 (3) Step of adding thermally expandable particles

 This is a step of uniformly adding a predetermined amount of thermally expandable particles to a thermosetting resin as a base resin of the adhesive. In addition, when adding the thermally expandable particles, it is preferable to set the environmental temperature at the time of addition to be equal to or lower than the foaming temperature so that the thermally expandable particles do not foam on the way, and to be 10 ° C. or higher than the foaming temperature. More preferably, the temperature is low. Example

 Hereinafter, the present invention will be described in more detail with reference to examples. However, needless to say, the embodiment shows one embodiment of the present invention, and the scope of the present invention is not limited to the description of the embodiment.

[Example 1]

 (1) Preparation of water-peelable adhesive composition

 In a melting pot maintained at 180 ° C, 100 parts by weight of SIS block copolymer as a base resin and 0.2 parts by weight of a phenolic antioxidant were contained, and a planetary mixer was used. The mixture was stirred for 3 hours to uniformly dissolve. Next, 30 parts by weight of a C5-based hydrogenated petroleum resin and a KI gel 201 K-F2 (Kuraray) comprising a crosslinked isobutylene-monomaleic anhydride copolymer were used.

35 parts by weight, average particle size 15 m, water absorption magnification 200 times), 7 parts by weight of polyethylene glycol monostearyl ether (HLB: 15.7) as a surfactant, plasticizer as a plasticizer Liquid paraffin (flash point: 256 ° C., density: 0.865 g Z cm ³ ) was contained in a melting pot at a ratio of 5 parts by weight. Further, the mixture was stirred for 1 hour using a planetary mixer, and it was confirmed that each component was uniformly melted and mixed. Thus, a water-peelable adhesive composition of Example 1 was obtained. In Table 1, the SIS block copolymer used in Example 1 was used. The body is represented by A1, the water-absorbent crosslinked polymer is represented by B1, and the tackifier (C5 hydrogenated petroleum resin, softening point: 100 ° C, average molecular weight: 650) is represented by C1, The activator is denoted by D1.

 (2) Evaluation of water-peelable adhesive composition

 ① Initial adhesive strength

Using an applicator for hot melt at 180 ° C and 0.98 MPa (1 O kgf / cm ^z ) on an aluminum plate (1.5 mm thick, 10 Omm long, 25 mm wide) An adhesive composition having a thickness of about 1 mm was applied. From there, another aluminum plate was laminated (lamination area: 12.5 x 25 mm ² ) and left as it was at room temperature for 24 hours to obtain a paste piece (measurement number = 5). Next, the initial adhesive strength (tensile shear bond strength) was measured using a tensile tester at a tensile speed of 20 mmZ in accordance with JISK 6850 (Test method for tensile shear bond strength of adhesive). .

② Adhesive strength after water absorption 1

 The paste (measuring number = 5) was immersed in water at room temperature, and the adhesive strength after standing for 6 hours and 12 hours in that state was measured in the same manner as the initial adhesive strength.

 ③ Adhesive strength after water absorption 2

 The test pieces (measured number = 5) were immersed in warm water at 60 ° C, and the adhesive strength after leaving for 3 hours and 6 hours in that state was measured in the same manner as the initial adhesive strength.

[Examples 2 to 5]

As shown in Table 1, in Example 2, the effect of reducing the amount of the surfactant used in Example 1 was examined, and in Example 3, a water-absorbent crosslinked polymer and adhesive which were different from Example 1 were used. The amount of the tackifier and the surfactant used was examined.In Example 4, the effect of changing the type of the surfactant in Example 3 was examined.In Example 5, the tackifier and the surfactant in Example 1 were used. The effects of not using an activator were examined separately. As can be understood from the results in Table 1, in Example 2, since the amount of the surfactant used was lower than that in Example 1, the initial adhesive strength increased, but the adhesive strength after water absorption tended to decrease. Has decreased. In Example 3, while the amount of the water-absorbent crosslinked polymer used in Example 1 was increased, the initial adhesive force was further increased because the amount of the tackifier and the surfactant was smaller than the amount used. At the same time, the tendency of the adhesive strength to decrease after water absorption became larger. In Example 4, it is considered that the type of the surfactant in Example 3 was changed, but the initial adhesive strength was slightly lower than that in Example 3, but the adhesive strength after water absorption was higher. The tendency of the decline in the number has increased. Also, in Example 5, it seems that the surfactant in Example 1 was not used, but the initial adhesive strength was slightly increased compared to Example 1, but the adhesive strength after water absorption decreased. It has become small.

[Comparative Example 1]

 As shown in Table 1, in Comparative Example 1, the change in adhesion after water absorption was examined without using the tackifier and surfactant in Example 1 and without adding a water-absorbing crosslinked polymer or the like. As can be understood from the results in Table 1, in Comparative Example 1, there was no significant difference between the initial adhesive strength and the adhesive strength after water absorption because no water-absorbing crosslinked polymer was added. I couldn't see it.

[Comparative Example 2]

As shown in Table 1, in Comparative Example 2, the change in adhesive force after water absorption was examined by adding a small amount of the tackifier without adding the water-absorbing cross-linked polymer of Example 1. As can be understood from the results in Table 1, in Comparative Example 2, there was no significant difference between the initial adhesive strength and the adhesive strength after water absorption because no water-absorbing bridge polymer was added. I couldn't see it. table 1

 * Base resin: A 1 (S I S block copolymer)

 * Water-absorbing crosslinked polymer: B 1 (crosslinked isobutylene maleic anhydride copolymer)

* Tackifier C 1 (C5 hydrogenated petroleum resin)

 * Surfactant D 1 (polyethylene glycol monostearyl ether)

 D 2 (decaglycerin tristearyl ester)

 * Mixing unit .PI.

* Adhesion unit Pa (-NZmm ² )

[Example 6]

 (1) Preparation of water-peelable adhesive composition

Under the condition that a relatively large amount of tackifier is added to the water-peelable adhesive composition. The influence of the average particle size on the water-absorbent crosslinked polymer was studied. That is, 30 parts by weight of a SIS block copolymer as a base resin and 0.2 parts by weight of a π-nor-based antioxidant were contained in a melting pot maintained at a temperature of 180 ° C. Thereafter, the mixture was stirred for 3 hours using a planetary mixer to uniformly melt. Next, 50 parts by weight of C5 hydrogenated petroleum resin, K201-F2 as a water-absorbing cross-linked polymer (average particle diameter 30〃m, water absorption magnification 200 times, in Table 2 , B2)) in a melting pot with 21 parts by weight of liquid paraffin (flash point: 256 ° density: 0.865 cm ³ ) as a plasticizer at a ratio of 5 parts by weight. Housed. Further, the mixture was stirred for 1 hour using a planetary mixer, and it was confirmed that each component was uniformly melted and mixed. Thus, a water-peelable adhesive composition of Example 6 was obtained.

(2) Evaluation of water-peelable adhesive composition

 Adhesion strength after immersion in water and hot water (60 ° C) for 6 hours as in Example 1.

(Adhesive strength after water absorption 1 and Adhesive strength after water absorption 2) were measured and evaluated. As a result, it is considered that the tackifier was added in a relatively large amount. After immersion in water for 6 hours, no remarkable decrease in the adhesive strength was observed, but the temperature was not reduced by warm water (60 ° C). It was confirmed that the adhesive strength was reduced to about 1 Z3 of the initial adhesive strength when using.

[Examples 7 to 11]

 As shown in Table 2, in Examples 7 to 11, water exfoliation was performed in the same manner as in Example 6, except that the type of water-absorbent crosslinked polymer, the average particle size, and the amount added were changed. A mold adhesive composition was prepared and evaluated.

As a result, in Example 7, no significant decrease in adhesive strength was observed after immersion in water for 6 hours, but almost no adhesive strength was exhibited when hot water (60 ° C) was used. Confirmed that it will not be. Also in Example 8, no significant decrease in adhesive strength was observed after immersion in water for 6 hours, but almost no adhesive strength was exhibited when warm water (60 ° C) was used. Make sure it ’s gone Was. Also, in Example 9, although no remarkable decrease in adhesive strength was observed after immersion in water for 6 hours, when hot water (60 ° C.) was used, the adhesive strength was almost zero. It was confirmed that expression did not occur. However, in Example 9, although it seems that the water-absorbent crosslinked polymer having a large average particle size was used, the initial adhesive strength tended to be low. Also, in Examples 10 and 11, although no remarkable decrease in the adhesive strength was observed after immersion in water for 6 hours, hot water was used.

(60 ° C), it was confirmed that the adhesive force hardly appeared.

[Comparative Example 3]

As shown in Table 2, in Comparative Example 3, an adhesive composition was prepared and evaluated in the same manner as in Example 6, except that the water-absorbent crosslinked polymer in Example 6 was not added. As a result, in Comparative Example 3, since no water-absorbent crosslinked polymer was added, no decrease in adhesive strength was observed even after immersion in water and warm water for 6 hours.

Table 2

 * Base resin: A 1 (S I S block copolymer)

 * Water-absorbing cross-linked polymer

B 2: Crosslinked isobutylene maleic anhydride copolymer, average particle size 30 jUm B 3: Crosslinked isobutylene maleic anhydride copolymer, average particle size 150〃 m B 4: Crosslinked isobutylene maleic anhydride copolymer, average particle size 1400 m B 5 _: polyacrylate polymer, average particle size 30 im B 6: polyacrylate polymer, average particle size 150 ju m

* Tackifier: C 1 (C5 hydrogenated petroleum resin)

 * Mixing unit

* Adhesion unit MP a (= N / mm ² )

[Example 12]

The water-peelable adhesive composition obtained in Example 1 was applied from a hot melt applicator under the conditions of 180 ° C and 0.98 MPa (1 O kgf / cm2). Then, a screen mesh for screen printing (made of polyamide, 30 cm x 30 cm) and a metal frame (made of aluminum) were bonded and fixed. In this state, no screen mesh was peeled off from the metal frame where screen printing was performed 50,000 times. Next, when the screen mesh was immersed in warm water at 60 ° C for 10 minutes, it was confirmed that the screen mesh was naturally separated from the metal frame. Therefore, according to the present embodiment, since no organic solvent is used, there is no effect on the human body and there is no flammability problem. In addition, the screen mesh peeling operation after screen printing can be performed easily and in a short time. Now you can do it. If a conventional hot melt adhesive is used, it must be immersed in methyl ethyl ketone at 60 ° C for at least one hour, and then scraped off using a metal spatula, which damages the metal frame. Many cases were seen.

[Example 13]

The water-peelable adhesive composition obtained in Example 1 was applied from a hot melt applicator at 180 ° C. and 0.98 MPa (1 O kgf / _cm 2). Then, the heat insulating material (hard urethane rubber) used for the refrigerator and the metal housing (made of painted aluminum) were bonded and fixed. In this state, the refrigerator was assembled, and a continuous test was performed for 500,000 hours at an ambient temperature of 60 ° C. However, no detachment of the heat insulating material from the metal casing was observed. Next, the refrigerator was disassembled, and the components consisting of the heat insulating material and the metal casing were taken out. After hot water at 95 ° C was showered at the junction for 10 minutes, the metal casing was removed. From this, it was confirmed that the heat insulation material was separated from nature. Therefore, according to the present embodiment, the heat insulating material can be easily and quickly peeled off from the metal housing. <Also, since the metal housing has no risk of being damaged, it can be reused as it is. Now you can. When a conventional adhesive was used, it was necessary to use a metal spatula to peel off the heat insulating material from the metal housing, and the metal housing was often damaged.

[Example 14] (1) Preparation of peelable adhesive composition combined with heat

 The type of adhesive base resin was studied. That is, in a container, 100 £ of Epikoto 828 (manufactured by Japan Epoxy Resin Co., Ltd.), 75 g of 1 gel 201 K-F2 (manufactured by Kuraray Co., Ltd.), and 75 g of thermally expandable particles After adding 25 g of Matsumoto Microsphere F-30D (manufactured by Matsumoto Yushi Seiyaku Co., Ltd.), the mixture was stirred for 1 hour using a mixer to uniformly mix the components. Next, after adding 5 Og of epomate B002 (manufactured by Japan Epoxy Resin Co., Ltd.) as a curing agent, the mixture was further stirred for 5 minutes to obtain a peelable adhesive composition combined with heat.

 (2) Evaluation of peelable adhesive composition combined with heat

 As in Example 1, after the measurement sample was prepared, the initial adhesive force was measured, and the measurement sample was placed in hot water (90 ° C) and a heating oven (105 ° C, 120 ° C). Was placed, and the self-peeling time was measured. As a result, as shown in Table 3, an extremely high initial adhesive strength of 7.5 MPa was obtained. -On the other hand, it was difficult to self-peel within 12 hours by heat treatment, but it was possible to self-peel in about 7 to 9 hours when using hot water It was confirmed.

[Example 15 to 20]

As shown in Table 3, the effect of the amount of thermally expandable particles added on the initial adhesive strength, self-peeling time in hot water and a heating oven, the effect of the type of water-absorbent resin, and the thermosetting resin (reactive acrylic) The effects of the type of resin) and the effects of adding surfactants and coupling agents were studied. In Table 3, the X mark means that self-peeling does not occur even after being left for 12 hours under the condition of water absorption Z heating. As a result, if the added amount of the heat-expandable particles is 40 parts by weight or less, the initial adhesive strength is high. It was confirmed that a heat-releasing adhesive composition was obtained. In addition, even if the type of the water-absorbing resin or the type of the thermosetting resin is changed, the self-peeling is difficult under the above heat treatment conditions. It was confirmed that a self-peeling peelable adhesive composition capable of self-peeling was obtained in the following immersion time. Furthermore, by adding a surfactant, it is difficult to perform self-peeling under the above heat treatment conditions, and only when hot water is used, self-peeling that can be self-peeled in three hours or less is possible. It was confirmed that a mold adhesive composition was obtained.

 Table 3

 * Base resin: A 1: S I S block copolymer

 A2: Epikote 828, A3: Epometo B002

 A4: Hardlock C-320— (-03A, A5: Hardlock G-320— K-03B * Water-absorbent crosslinked polymer

 B 2: Crosslinked isobutylene maleic anhydride copolymer, average particle size 30〃m

B 5: Polyacrylate polymer, average particle size 30 jU m

* Mixing unit * Adhesion unit: MP a (= N / mm ² ) Industrial applicability

 As described above, according to the water-peelable adhesive composition of the present invention, the base resin of the adhesive contains the water-absorbing crosslinked polymer in a predetermined amount, and By including the activator in a predetermined amount range, the initial adhesive strength is as strong as before, but when immersed in water, warm water or even hot water, the water-absorbent crosslinked polymer absorbs water and swells, It has become possible to easily separate an adherend, for example, glass and an accessory.

 Further, according to the heat-adhesive peelable adhesive composition of the present invention, a high initial adhesive strength is obtained by including the water-absorbent crosslinked polymer and the heat-expandable particles in the thermosetting adhesive in a predetermined amount range, respectively. On the other hand, self-exfoliation does not occur by heat treatment at about 120 ° C, and only when hot water is used, the water-absorbing cross-linked polymer absorbs water and the thermal expansion of the heat-expandable particles. As a result, self-peeling became possible within 12 hours.

 Therefore, according to the peelable adhesive composition of the present invention, a cosmetic container, a medicine container, an aromatic container, a beverage container, a seasoning container, an article storage container, a gas storage container, a liquid crystal storage container (including an LCD panel) ), And circuit board storage container (including the housing for electrical components). It is expected to be used for joining composite containers where collection of each component is particularly desired.

 Further, according to the peelable adhesive composition of the present invention, since the adhesive strength can be reduced as desired, an adhesive for screen fixing for screen printing, an adhesive for temporary fixing when transporting semiconductor components, a masking tape Adhesives, bolts (screw) adhesives to prevent loosening, wallpaper adhesives, decorative films (marking film) adhesives, glass fixing adhesives, magnet fixing adhesives, metal fixing adhesives, tiles It is expected to be suitably used for adhesives for wood, wood, glue for books, glue for optical fiber connection, glue for toys, etc.

Further, in the peelable adhesive composition of the present invention, the type of the base resin is considered. It can also be used as a molding resin by taking into account or adding inorganic particles.For example, it can be suitably used as a resin for semiconductor encapsulation, an electrically insulating resin, a resin for forming a circuit board, and the like. Be expected.

 Further, according to the method for producing a peelable adhesive composition of the present invention, the base resin of the adhesive contains the water-absorbing crosslinked polymer and further the heat-expandable particles in a predetermined amount range, so that the water-absorbing property is improved. The cross-linkable polymer and the heat-expandable particles can be uniformly mixed and dispersed, and a peelable adhesive composition having a reduced adhesive strength after water absorption can be obtained effectively.

Claims

The scope of the claims

1. A release-type adhesive composition in which the adhesive strength is reduced after water absorption, wherein the water-absorbent crosslinked polymer is contained in an amount of 1 to 200 parts by weight based on 100 parts by weight of the base resin of the adhesive. A peelable adhesive composition comprising:

 2. When the water-absorbent crosslinked polymer is in the form of particles, the average particle diameter is set to a value in the range of 1 to 800 m, and when the water-absorbent crosslinked polymer is in the form of fibers, the average fiber length is set. 2. The peelable adhesive composition according to claim 1, wherein the value is in the range of 2 to 6 O mm.

 3. The peelable adhesive composition according to claim 1, wherein the water absorption capacity of the water-absorbent crosslinked polymer is set to a value within a range of 5 to 1000 times.

4. The water-absorbent crosslinked polymer is a crosslinked product of a hydrolyzate of a starch-acryl nitrile graft polymer, a crosslinked product of a neutralized product of a starch-acrylic acid graft polymer, and a vinyl acetate-acrylic acid ester copolymer Crosslinked product of genidized product, crosslinked product of hydrolyzate of acrylonitrile copolymer, crosslinked product of hydrolyzate of acrylamide copolymer, crosslinked product of partially neutralized polyacrylic acid, crosslinked polyvinyl containing carboxyl group 4. The composition according to claim 1, which is at least one selected from the group consisting of an alcohol-modified product, a cross-linked isobutylene-anhydrous maleic acid copolymer, a polyethylene oxide cross-linked product, and a cross-linked urethane-modified product. The peelable adhesive composition according to any one of the preceding claims.

 5. The surfactant according to any one of claims 1 to 4, wherein the surfactant is contained in a range of 0.001 to 20 parts by weight with respect to 100 parts by weight of the base resin of the adhesive. 3. The peelable adhesive composition according to item 1.

 6. The base resin of the adhesive is a rubber resin, and the tackifier is contained in the range of 1 to 800 parts by weight based on 100 parts by weight of the base resin of the adhesive. The peelable adhesive composition according to any one of claims 1 to 5, which is characterized in that:

7. The peelable adhesive composition according to any one of claims 1 to 6, wherein a base resin of the adhesive is a hot melt type resin.

8. The peelable adhesive composition according to any one of claims 1 to 5, wherein a base resin of the adhesive is a thermosetting resin.

 9. The heat-expandable particle is contained in a range of 1 to 300 parts by weight with respect to 100 parts by weight of the base resin of the adhesive. Peelable adhesive composition.

 10. In a method for producing a peelable adhesive composition in which the adhesive strength is reduced after absorbing water,

 A step of preparing a base resin of the adhesive in a molten state,

 With respect to 100 parts by weight of the base resin of the adhesive, a water-absorbent crosslinked polymer having an average particle diameter of 1 to 800 μm and a water-absorbent crosslink having an average fiber length of 2 to 6 Omm A dry blending step of adding the molecule or one of the water-absorbent crosslinked polymers in a range of 1 to 200 parts by weight,

 A method for producing a peelable adhesive composition, comprising:

 1 1. In a method for producing a peelable adhesive composition in which the adhesive strength is reduced after absorbing water,

 A step of preparing a thermosetting resin as a base resin of the adhesive; and adding 1 to 200 parts by weight of a water-absorbing crosslinked polymer to 100 parts by weight of the base resin of the adhesive. Process and

 A method for producing a peelable adhesive composition, comprising:

 12. A release-type adhesive further comprising a step of adding heat-expandable particles in a range of 1 to 300 parts by weight to 100 parts by weight of the base resin of the adhesive. A method for producing the composition.