JP2005008871A - Double-sided self-adhesive foam sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a double-sided self-adhesive foam sheet capable of being used as an adhesive of freely attachable and detachable type when a plastic product, a metal product, a glass product, or a ceramic product of every kind, for example, an article for kitchen use, an article for pet use, an article for daily use, and an article for stationery and office use, including a tissue box, an aluminum foil box, or a wrapping film box, of which at least one of the surfaces is flat and which is relatively lightweight, or a wooden or paper product of which the surface is subjected to mirror polishing, is fastened to a support surface of glass, metal, plastic, paper, etc., in a freely attachable and detachable manner. <P>SOLUTION: This double-sided self-adhesive foam sheet is used for fastening the product of which at least one of the surfaces is flat to the support surface of the glass, the metal, the plastic, the paper, etc., in the freely attachable and detachable manner, wherein the foam sheet comprises such a foam sheet as to have an open-cell structure obtained by mechanically foaming an acrylic copolymer emulsion, and the sheet has an adhesive force to plate glass for mirror surface use of 0.4-4 N and a density of 0.1-0.35 g/cm<SP>3</SP>. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is, for example, various plastic products, metal products, glass products, which are flat and relatively light on at least one surface, such as kitchen utensils such as tissue boxes, aluminum wheel boxes, wrapping film boxes, pet articles, daily necessities, and stationery items. The present invention relates to a double-sided self-adhesive foam sheet used as a removable adhesive when a ceramic product or a wood / paper product with a mirror-coated surface is detachably fixed to a supporting surface such as glass, metal, plastic, paper, etc. Is.

Conventionally, a double-sided pressure-sensitive adhesive sheet has been used to fix an article having at least one flat surface to a supporting surface such as glass, metal, plastic, or paper. However, when the article is peeled off from the support surface, the pressure-sensitive adhesive of the sheet adheres to the support surface, and the appearance of the support surface is unsightly.
Therefore, Japanese Utility Model Laid-Open No. 54-165550 proposes a double-sided pressure-sensitive adhesive tape in which a cloth is attached to one side of a base made of foam sheet, and an adhesive layer is provided on the exposed surface of the base and the surface of the cloth. Yes. This double-sided pressure-sensitive adhesive tape is used to fix an article by sticking the article to be fixed to the supporting surface to the fixing surface to the supporting surface, and sticking this tape to the supporting surface. When the article is peeled off from the support surface, the substrate made of the foam sheet of the tape is torn off, leaving a part of the substrate and the adhesive layer on the substrate side on the support surface.
For this reason, this double-sided adhesive tape not only cannot be reused after the article has been peeled off from the support surface, but also the adhesive layer and a part of the substrate remain in the peeled article. In addition, there is a problem that it is difficult to separate a part of the substrate.
Japanese Utility Model Publication No. 54-165550

  In order to solve the above-mentioned problem, the present invention is a double-sided self-adhesive foam sheet capable of detachably fixing an article having at least one flat surface to a supporting surface such as glass, metal, plastic or paper. In the case where the sheet is peeled off from the support surface or the article, the adhesive or other fixing means does not remain on the support surface or the article. It is an object of the present invention to provide a double-sided self-adhesive foam sheet that can be reused with a sticking / peeling property.

In order to solve the above-described problems, the double-sided self-adhesive foam sheet of the present invention is a double-sided self-adhesive for fixing an article having at least one flat surface to a supporting surface such as glass, metal, plastic, paper, etc. In the foam sheet, the foam sheet is a foam sheet having an open cell structure obtained by mechanical foaming of an acrylic copolymer emulsion, and has an adhesive force of 0.4 to 4 N and a density of 0. It is a double-sided self-adhesive foam sheet characterized by being 1 to 0.35 g / cm ³ .
The acrylic copolymer emulsion in the present invention includes an acrylic copolymer synthesized from an acrylic ester monomer and / or a methacrylic ester monomer and a monomer having a functional group. The acrylic copolymer emulsion may contain a crosslinking agent.
In the present invention, mechanical foaming means a foaming method in which ambient air is mechanically refined with a stirring blade or the like and mixed into the emulsion.

As said acrylic copolymer, what is superposed | polymerized by the emulsion polymerization method generally performed is used preferably.
Specifically, acrylic acid ester monomer and / or methacrylic acid ester monomer (hereinafter collectively referred to as “(meth) acrylic acid monomer”) in the presence of an emulsifier and water as a solvent. A polymerized acrylic copolymer, or a monomer having a functional group that can be copolymerized with the monomer and can form a crosslinked structure by reacting with a crosslinking agent. An acrylic copolymer polymerized using water as a solvent in the presence of an emulsifier.
Further, in order to adjust the physical properties of the foam, it may be polymerized by adding a (meth) acrylate monomer and another monomer copolymerizable with the monomer having the above functional group. .
During the polymerization, a polymerization initiator, a chain transfer agent, and the like are added as necessary, and at the same time, the polymerization reaction is performed while adjusting the temperature conditions to prepare the target emulsion.
The weight ratio of the monomer having the above functional group is preferably 1 to 10% by weight with respect to the total of the monomers, and if it is less than 1% by weight, the foam obtained is not sufficiently crosslinked and water resistance is poor. It is conceivable that the foam breaks when it is peeled off in a wet state. Conversely, if it exceeds 10% by weight, the crosslink density is excessively increased, the adhesiveness (tack) of the foam surface is lowered, and the adsorptive power is deteriorated.

  Here, (meth) acrylic acid ester is a condensate of (meth) acrylic acid with aliphatic alcohol, alicyclic alcohol, or aromatic alcohol.

  Examples of (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, n-butyl (meth) acrylate, Iso-butyl (meth) acrylate, benzyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, (meth) acrylic N-nonyl acid, iso-nonyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, n-amyl (meth) acrylate, iso (meth) acrylate -Amyl, lauryl (meth) acrylate, benzyl (meth) acrylate, cyclohex (meth) acrylate A Le etc., preferably (meth) acrylate, (meth) acrylic acid n- butyl, (meth) nonyl iso- acrylate.

  Examples of monomers having the above functional groups include carboxyl group-containing monomers such as (meth) acrylic acid, itaconic acid, crotonic acid, fumaric acid and maleic acid, and acids such as ethylenically unsaturated polycarboxylic acid anhydrides. Monomers with anhydrides, n-methylol (meth) acrylamide, allyl alcohol, methallyl alcohol, hydroxylmethyl (meth) acrylate, 1-hydroxylethyl (meth) acrylate, 2-hydroxylethyl (meth) acrylate , Hydroxyl-containing monomers such as hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, β-aminoethyl vinyl ether, dimethylaminoethyl Vinyl ether, vinylamine, vinylmethylamine, Amino such as nilethylamine, vinyldimethylamine, vinyldiethylamine, allylamine, allyldimethylamine, methallyldimethylamine, vinyldiphenylamine, allyldimethylamine, allyldimethylamine, methallyldiethylamine, allyldimethyl, methallyldiethylamine, p-aminostyrene Group-containing monomers, (meth) acrylamide, diacetone (meth) acrylamide, crotonamide, itaconediamide, methylitaconamide, maleinamide, N-butoxymethyl (meth) acrylamide, N-butoxyethyl (meth) acrylamide, N -Methoxymethyl (meth) acrylamide, N-butoxyethyl (meth) acrylamide, N-methoxymethyl (meth) acrylamide, Nn-propioxy Amide group-containing monomers such as cymethyl (meth) acrylamide, N-methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, glycidyl (meth) acrylate, vinyl Epoxy group-containing monomers such as glycidyl ether and allyl glycidyl ether, divinylbenzene, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polypropylene di (meth) acrylate, trimethyl Uses monomers with polyfunctional unsaturated bonds such as propane poly (meth) acrylate, glycerin poly (meth) acrylate, poly (meth) acrylate of terminal hydroxyl group-containing polyester, diallyl phthalate, etc. Rukoto can.

  Examples of the other monomer include styrene, p-chlorostyrene, acrylonitrile, vinyl acetate, vinyl chloride, vinylidene chloride, butadiene, isoprene, chloroprene and the like.

  Emulsion polymerization of these monomers usually uses 100 to 200 parts by weight of water with respect to a total of 100 parts by weight of the monomers, and in the presence of an emulsifier and a polymerization initiator, optionally a chain transfer agent, It is carried out by adding various electrolytes, pH adjusting agents and the like.

As the above-mentioned emulsifier, one or more surfactants such as an anionic surfactant, a nonionic surfactant, a cationic surfactant, and an amphoteric surfactant can be used.
Anionic surfactants include fatty acid alkali metal salts, higher alcohol sulfates, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl phenyl ether sulfates, fatty oil sulfates, aliphatic amines. Or sulfates of aliphatic amides, sulfonates of dibasic fatty acid esters, sulfonates of aliphatic amides, alkyl or alkenyl sulfonates, alkyl aryl sulfonates, alkyl sulfosuccinates, formalin condensed naphthalene sulfonates Further, a phosphate ester salt of an aliphatic alcohol, a polyoxyethylene alkyl (phenyl) ether phosphate ester salt, or the like can be used.
Of these, sodium lauryl sulfate, sodium dodecylbenzene sulfonate, sodium diphenyl ether disulfonate, and sodium dialkylether sulfonate succinate are particularly preferably used.

As the nonionic surfactant, polyoxyethylene alkyl ester, polyoxyethylene alkyl ether, polyoxyethylene allyl ether, glycerin fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester and the like can be used.
The amount of the emulsifier added is generally about 0.5 to 10% by weight, preferably 1 to 3% by weight, based on the monomer component.
If the amount of the emulsifier added is too small, uniform emulsion polymerization becomes difficult. If the amount is too large, problems such as deterioration of the water resistance of the foam produced will occur.

As polymerization initiators, potassium persulfate, ammonium persulfate, hydrogen peroxide, cumene hydroperoxide, isopropylbenzene hydroperoxide, paramentane hydroperoxide, benzoyl peroxide, di-1-butyl peroxide, dilauroyl peroxide And azo compounds such as azobisisobutyronitrile, azobisisovaleronitrile, azobisisocapronitrile, azobis (phenylisobutyronitrile), and the like.
The addition amount of the initiator is preferably 0.03 to 2% by weight, more preferably 0.05 to 1% by weight, based on the monomer.
If the amount of the initiator added is too small, problems such as excessive polymerization time and the molecular weight of the resulting polymer are too large to be used. On the other hand, when the amount of the polymerization initiator added is too large, there arises a problem that the molecular weight of the resulting polymer is too low and the produced foam becomes brittle.

  If necessary, a crosslinking agent is added to and mixed with the emulsion obtained as described above to form a crosslinkable emulsion. In addition, you may foam a crosslinkable emulsion at the time of addition of a crosslinking agent. Further, an additive may be added before or simultaneously with the addition of the cross-linking agent in order to improve processability for foam production and improve various properties of the resulting foam.

An epoxy compound having an epoxy group is used as the crosslinking agent. For example, propylene glycol diglycidyl ether represented by the formula (1) (there is Denacol EX-911 manufactured by Nagano Kasei), N, N, N ′, N′-tetraglycidyl-m-xylenediamine represented by the formula (2) (There is Tetrad-X manufactured by Mitsubishi Gas Chemical Company, Inc.).

Further, rubber may be added to improve the strength of the foam sheet of the present invention. As rubber, isoprene rubber, butadiene rubber, butyl rubber, styrene-butadiene rubber, hydrogenated styrene-butadiene rubber, ethylene-propylene rubber, ethylene-butene-1 copolymer (ethylene-butene rubber), ethylene-pentene-1 copolymer weight Polymer, ethylene-hexene-1 copolymer, ethylene-heptene-1 copolymer, ethylene-octene-1 copolymer, ethylene-nonene-1 copolymer, ethylene-decene-1 copolymer, epichlorohydride Rubber, acrylonitrile-butadiene rubber, styrene-ethylene-isoprene rubber, hydrogenated styrene-ethylene-isoprene rubber, acrylic rubber, urethane rubber, silicone rubber, etc. can be used, but preferably ethylene-propylene rubber, hydrogenated in the present invention. Styrene-butadiene rubber Hydrogenated styrene-ethylene-isoprene rubber, ethylene-butene-1 copolymer, ethylene-pentene-1 copolymer, ethylene-hexene-1 copolymer, ethylene-heptene-1 copolymer, ethylene-octene-1 A copolymer, an ethylene-nonene-1 copolymer, and an ethylene-decene-1 copolymer. These rubbers may be used alone or in combination of two or more by an appropriate combination.
And 10-60 weight part of rubber | gum can be added with respect to 100 weight part of acrylic copolymers, Preferably it is 25-40 weight part. If the rubber mixing amount is too small, the tear strength of the resulting sheet may be insufficient and may be damaged when the sheet is peeled off. If the rubber mixing amount is too large, the resulting sheet will be sticky. May be insufficient.

Examples of additives that can be used include fillers, antiseptic / antifungal agents, foam stabilizers, foaming aids, gelling agents, flame retardants, tackifiers, pigments, dyes, and those capable of generating negative ions.
It is also possible to blend other resin emulsions in addition to the acrylic copolymer emulsion as a modification of the emulsion, and in particular to replace a part of the acrylic copolymer emulsion for the purpose of improving the tensile strength. You can also add a urethane emulsion.

  As the filler, calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, barium hydroxide, clay, kaolin, glass powder and the like can be used.

  Examples of the antiseptic / antifungal agent include dihydroxydichlorophenylmethane, sodium pentachlorophenate, 2,3,4,6-tetrachloro-4- (methylsulfonyl) pyridine, and 2,3,5,6-tetrachloro-4. -(Methylsulfonyl) pyridine, bis (tributyltin) oxide, hexahydro-1,3,5-triethyl-s-triazine, silver complex, zinc complex and the like can be used.

  As the foam stabilizer, ammonium stearate, alkyl sulfosuccinate, quaternary alkyl ammonium chloride and the like can be used.

  As the foaming aid, sodium lauryl sulfate, sodium alkyldiphenyl ether disulfonate, sodium polyoxyethylene alkylphenol ether sulfate and the like can be used.

  As gelling agents, ammonium salts such as ammonium acetate, ammonium chloride, and ammonium carbonate, alkylphenol alkylene oxide adducts, polyvinyl methyl ether, polypropylene glycol, polyether polyformal, methyl cellulose, hydroxyethyl cellulose, and silicon gelling agents are used. it can.

  As the flame retardant, phosphate ester compounds, halogen phosphate ester compounds, ammonium polyphosphate, antimony trioxide, zinc borate, barium metaborate, ammonium hydroxide, magnesium hydroxide, and the like can be used.

  The tackifier is added to improve adhesion to a glass surface, a metal surface, etc., for example, gum rosin, tall oil rosin, wood rosin, hydrogenated rosin, disproportionated rosin, polymerized rosin, maleated rosin, Rosin resin such as rosin glycerin ester, hydrogenated rosin / glycerin ester, terpene resin such as terpene resin, terpene phenol resin, aromatic modified terpene resin, aliphatic petroleum resin, alicyclic petroleum resin, aromatic A compound selected from petroleum resins such as petroleum resins, coumarone indene resins and the like can be used.

  Examples of pigments and dyes include titanium oxide, carbon black, bengara, and quinacridone.

  Any negative ion can be generated as long as it can generate negative ions. For example, tourmaline powder or pellets and zirconium powder can be used. Those mixed are preferable, and negative ions can be effectively generated by adding them to the sheet of the present invention.

  The above acrylic copolymer emulsion is foamed by mixing air with mechanical foaming and stirring. That is, a certain amount of air is mixed in the emulsion and stirred continuously or intermittently with an Oaks mixer, whipper or the like to form a foamed emulsion. This foamed emulsion has a soft cream shape.

  This foamed emulsion is coated on a substrate and dried by heating to solidify to form a foamed layer (foam). At this time, if the foamed emulsion is made into a crosslinkable foamed emulsion, the functional group contained in the acrylic copolymer and the epoxy group contained in the epoxy compound serving as the crosslinking agent react to form a crosslinked structure, thereby absorbing shock. A foam having properties and strength.

As the base material, any plastic film can be applied, but it is tough, excellent in heat resistance, and has an appropriate releasability from the foam obtained from the acrylic copolymer emulsion in the present invention. A film can be preferably used.
As this polyester film, uniaxially stretched PET, biaxially stretched PET, A-PET, PET-G film, etc. can be used.
As for the thickness of a base material, 10-80 micrometers is preferable, More preferably, it is 38-50 micrometers. If it is less than 10 μm, wrinkles are likely to occur at the stage of forming the foam layer. Occurs.

As a coating method of the (crosslinkable) foamed emulsion to the substrate, a method using a generally known coating apparatus such as a roll coater, a reverse roll coater, a screen coater, a doctor knife coater, a comma knife coater, etc. can be adopted. In particular, a method using a doctor knife coater is preferable because a desired coating thickness can be obtained satisfactorily.
The coating may be a single-layer coating or a multi-layer coating. In the case of a multi-layer coating, each layer may not be the same type of emulsion.

The method of heat drying is not particularly limited as long as the foamed emulsion (crosslinkable) coated on the substrate can be dried and crosslinked. When coating in a batch mode, a normal hot air circulation type oven or the like can be used, and when coating in a continuous mode, a hot oil circulation hot air chamber, a far infrared heater chamber, or the like can be used.
The drying conditions are appropriately selected depending on the properties of the emulsion, the coating amount, the coating thickness, and the like.
In general, the temperature is suitably from 90 ° C to 180 ° C, but it is not a constant temperature, but is initially dried at a low temperature from the inside at a low temperature, gradually increased to a higher temperature in the latter stage, and sufficiently dried. It is particularly preferable to perform drying.

The obtained foam has an open-cell structure, and has an adhesive force of 0.4 to 4 N with respect to a plate glass for mirror use.
Based on the test method of JIS-Z0237, the adhesive strength with respect to the plate glass for mirror surface use is 180 ° pulling at a test piece width of 25 mm, a test piece length of 250 mm, a temperature of 23 ° C., a relative humidity of 50%, and a peeling speed of 300 mm / min. It means the adhesive strength at the time of peeling, and as shown in FIG. 1, after adhering a test piece 1 (only foam in the present invention) cut to a width of 25 mm and a length of 250 mm to a plate glass 2 for mirror surface use, the above conditions Thus, it is a measured value obtained by conducting a test in which the test piece 1 is peeled in the direction indicated by the arrow in FIG. 1, and in the present invention, it is important that this measured value is 0.4 to 4N.

  If it is a foam sheet having an adhesive strength of 0.4 to 4N, most small articles having a flat surface around them can be detachably attached to a support surface and a vertical support surface. Not only when the article stuck on the support surface is peeled off, the foam piece is not left on the support surface, and the foam sheet can be easily peeled off from the article. Can be used in the same manner.

In addition, the density, hardness, thickness, and the like of the foam sheet can be adjusted as appropriate depending on the mixing ratio of bubbles, the composition and solid content of the emulsion, the heat-drying solidification conditions, and the like.
Among these, it is important that the density is 0.1 to 0.35 g / cm 3. If the density is within this range, the foam can not only ensure the above-mentioned adhesive strength but also have good shock absorption. This density can be secured particularly by adjusting the amount of air mixed during mechanical foaming of the emulsion.

  The thickness of the foam sheet is preferably 0.3 to 5 mm, more preferably 0.5 to 1 mm. If it is less than 0.3 mm, the impact absorbability is not sufficient, and if it is thicker than 5 mm, it is difficult to stick the foam sheet to the curved surface.

  Thus, a double-sided self-adhesive foam sheet obtained by coating a (crosslinkable) foamed emulsion on a substrate and drying by heating is usually wound by a winder, and is transported and stored. After that, it is cut by a press cutter, a slitter or the like and processed into a size that is easy to use.

  In the double-sided self-adhesive foam sheet of the present invention, a foam made of an acrylic copolymer having an open-cell structure has an appropriate adhesive force and density, a supporting surface such as glass, metal, plastic, paper, etc., and at least one surface Is adhered to flat surfaces of articles that are flat and peels without leaving foam pieces on these surfaces. The foam after peeling maintains an appropriate adhesive force, and can be adhered and peeled again to the support surface and the flat surface.

Thus, in the double-sided self-adhesive foam sheet of the present invention, the foam serves as an adhesive material, and the substrate on which the foam is placed is transported and stored during the production of the double-sided self-adhesive foam sheet. This is necessary in the case of cutting and the like, and is unnecessary in the case of sticking to a support surface or an article. However, since the base material in the present invention has releasability with respect to the foam, it can be distributed while temporarily attached to the double-sided self-adhesive foam sheet as a release sheet of the double-sided self-adhesive foam sheet of the present invention.
Because of this releasability, another sheet having releasability with respect to the foam can also be temporarily attached to the surface of the double-sided self-adhesive foam sheet without the base material. Although the thickness of a release sheet is not specifically limited, 30-80 micrometers is preferable from surfaces, such as handleability.

  In the double-sided self-adhesive foam sheet of the present invention, an open-cell foam made of an acrylic copolymer has an appropriate adhesive force, so there is no need to separately provide an adhesive layer. It is an excellent foam sheet that can be peeled off without remaining on the surface and can also be reused.

In general, an article held on a vertical surface generates a peeling force by attempting to fall by its own weight. If an adhesive force exceeding the peeling force is applied to the article, the article can be prevented from falling. The double-sided self-adhesive foam sheet of the present invention is a foam sheet made of an acrylic copolymer having an open-cell structure and a specific adhesive strength / density, and exhibits an appropriate adhesive strength in close contact with the support surface and the article. Thus, it is possible to prevent the article fixed to the support surface from falling.
Moreover, since the double-sided self-adhesive foam sheet of the present invention follows the article even when the article is displaced by vibration or the like, the peeling force does not concentrate on one place, and the article can be fixed to the vertical surface.
Furthermore, the double-sided self-adhesive foam sheet of the present invention closely adheres to the article itself even if the article itself is easily deformed like a tissue paper storage box, so that the article falls due to the deformation of the article. Can also be prevented.

  And since the double-sided self-adhesive foam sheet of the present invention has a specific adhesive strength and density, in addition to the adhesive strength exceeding the peeling strength due to the weight of the above-mentioned article, it also has an appropriate peeling strength, When peeling an article attached to a surface from a support surface, or when removing an article or a foam sheet attached to a support surface, it should be removed beautifully and easily without leaving the foam sheet on the article or the support surface. Can

  Moreover, the double-sided self-adhesive foam sheet of the present invention is a monomer having a functional group that is reactive with an acrylate monomer and / or a methacrylic acid ester monomer and also reactive with a crosslinking agent. When it is obtained from an emulsion containing an acrylic copolymer synthesized by using a resin and also containing a cross-linking agent, the mechanical strength is improved, and when adhering to an article or a support surface, or when removing from it In addition, it does not tear and becomes very easy to use.

[Examples 1 to 10, Comparative Examples 1 and 2]
<Manufacture of acrylic copolymer>
Into the polymerization kettle, 2000 g of distilled water was added, and 15 g of sodium lauryl sulfate as an emulsifier and the monomers shown in Table 1 were added in the amounts shown in Table 1, and the potassium carbonate was adjusted to 65 ° C. while stirring. 1 g and 3 g of potassium persulfate were gradually added to carry out an emulsion polymerization reaction for 10 hours to obtain three types of acrylic copolymer emulsions A to C.

<Preparation of crosslinkable emulsion>
The cross-linking agents and additives shown in Table 2 were added to the acrylic copolymer emulsions A to C shown in Table 1 in the amounts shown in Table 2, mixed and stirred, and 12 types of cross-linking emulsions were prepared.
Each of the 12 types of crosslinkable emulsions was taken in a plastic beaker, and air was mixed in with a whipper until the specific gravity became 0.3 g / cc to prepare 12 types of crosslinkable foamed emulsions shown in Table 2.

Each of the crosslinkable foamed emulsions in Table 2 was coated on a polyethylene terephthalate film as a substrate with a doctor knife coater to a predetermined thickness, and then solidified by heating and drying under the heating conditions shown in Table 2. A foam layer with a thickness of 2 mm was obtained.
Each of the foam layers was peeled from the substrate to obtain a double-sided self-adhesive foam sheet of the present invention and comparative.

With respect to each of these double-sided self-adhesive foam sheets, the test method shown in FIG. 1 was used to measure the adhesive force against a glass sheet for mirror surface use and to measure the density. The results are also shown in Table 2.
The double-sided self-adhesive foam sheet was adhered to the plate glass by pressing the sheet upper surface with a roller (diameter 95 mm, width 45 mm, weight 2000 g) (two reciprocations at a speed of 20 mm / second).
Moreover, the surface which was in contact with the base material was the front surface, and the opposite side surface was the back surface.

In addition, the storage box 4 (hereinafter referred to as “tissue box”) of the tissue paper 3 is fixed on the glass plate 2 as shown in FIG. It was.
The tissue box 4 in this state is peeled off from the double-sided self-adhesive foam sheet 2 of the present invention and the comparison, and then the double-sided self-adhesive foam sheet 2 is peeled off from the glass plate 2, and the following items * 1 to * 4 are evaluated. Table 2 shows the evaluation results.

<* 1: About the fixed state of the double-sided self-adhesive foam sheet fixed on the support surface>
The double-sided self-adhesive foam sheet was pressed and fixed for 2 seconds so that the double-sided self-adhesive foam sheet was in close contact with the glass plate, and the fixed state was evaluated according to the following criteria.
A: There is a sufficient fixing force.
○: Although the fixing force is slightly inferior, it is not in a state of peeling off naturally.
(Triangle | delta): It is inferior to fixing force and is a state which peels naturally.
×: Cannot be fixed

<* 2: About the fixed state of the article fixed on the double-sided self-adhesive foam sheet>
On the double-sided self-adhesive foam sheet fixed to the support surface by the above method, the tissue box was fixed by pressing for 2 seconds with a force that does not cause the tissue box to be crushed, and the fixed state was evaluated according to the following criteria.
○: The tissue box is not naturally peeled off by its own weight.
X: Cannot be fixed.

<* 3: About the state where the article fixed on the double-sided self-adhesive foam sheet is peeled off>
The peeled state when the article (tissue box) fixed by the above method was peeled off at a speed of 500 mm / sec in the vertical direction was evaluated according to the following criteria.
○: The article was peeled off without destruction of the article and without any foam piece remaining on the article.
X: A piece of foam remains on the article.

<* 4: About the state where the double-sided self-adhesive foam sheet fixed on the support surface is peeled off>
The double-sided self-adhesive foam sheet fixed to the support surface (glass plate) by the above method was subjected to a 90 ° peel test at a speed of 500 mm / sec, and the peeled state at this time was evaluated according to the following criteria.
A: The double-sided self-adhesive foam sheet was peeled off without breaking the foam piece and remaining on the supporting surface.
○: Partial destruction was observed in the double-sided self-adhesive foam sheet, but the foam piece was peeled off without remaining on the support surface.
X: The foam piece remains on the support surface.

The cross-linking agents and additives in Table 2 are as follows, and the unit of blending is “g”.
Foam stabilizer A: Ammonium stearate Foam stabilizer B: Alkyl sulfosuccinate Gelling agent: Polypropylene glycol Crosslinker A: Melamine compound Crosslinker B: Epoxy compound Tackifier: Rosin resin emulsion Pigment: Carbon black water Dispersion black pigment (solid content 60% by weight)

Moreover, after fixing each of the double-sided self-adhesive foam sheets of Examples 1 to 10 with a force of close contact with the glass plate for 2 seconds, the tissue box was fixed on the double-sided self-adhesive foam sheet, Left for 2 weeks.
After standing for 2 weeks, the tissue box and the double-sided self-adhesive foam sheet were sequentially peeled off, and the peeled double-sided self-adhesive foam sheet was further left for 2 weeks.
Thereafter, each double-sided self-adhesive foam sheet was fixed on a glass plate in the same manner as described above, and a tissue box was fixed on the double-sided self-adhesive foam sheet. This tissue box could be well fixed on the glass plate through a double-sided self-adhesive foam sheet.
From this, it can be seen that the double-sided self-adhesive foam sheet of the present invention can be reused.

  In the above embodiment, the tissue box is fixed to the glass plate. However, instead of the tissue box, lightweight plastic products, metal products, glass products, ceramic products, and wood / paper products whose surfaces are mirror-coated are used. It could be attached to any place and easily removed.

[Examples 11-12, Comparative Examples 3-4]
An acrylic copolymer emulsion obtained by mixing 25 g of carbon black aqueous dispersion black pigment (solid content concentration 60 wt%) with 500 g of an acrylic copolymer emulsion (840R manufactured by Etec Co., Ltd., solid content concentration 57 wt%). The copolymer emulsion D (solid content concentration: 57% by weight) was put in a plastic beaker and mechanically foamed using a whipper until the specific gravity shown in Table 3 was obtained, thereby preparing four types of foamed emulsions.

Each of the foamed emulsions in Table 3 was coated on a polyethylene terephthalate film as a base material to a predetermined thickness using a doctor knife coater, and then solidified by heating and drying at 150 ° C. for 10 minutes to a thickness of 2 mm. Got the form.
Each of the foams was peeled from the substrate to obtain a double-sided self-adhesive foam sheet of the present invention and comparative.

<Measurement of density and adhesive strength>
For each of these double-sided self-adhesive foam sheets, the density is measured, and the adhesive strength to the glass sheet for mirror use is measured by the test method shown in FIG. 1, and paper obtained by cutting the bottom surface of the tissue box in place of the glass sheet is used. Measured the adhesive strength in the same manner as in FIG. These results are also shown in Table 3.
The double-sided self-adhesive foam sheet was adhered to the plate glass and the tissue box bottom paper by pressing on the double-sided self-adhesive foam sheet with a roller (diameter 95 mm, width 45 mm, weight 2000 g) as in Examples 1-10. 2 reciprocations at a speed of 20 mm / sec).
Moreover, the adhesive force after leaving the double-sided self-adhesive foam sheet stuck as mentioned above for 2 weeks was measured by the method of FIG. 1, and this result is also shown in Table 3.

<Fixability test of articles>
Affix the above double-sided self-adhesive foam sheet to the bottom of a tissue box (weight 220 g), press it with a force that does not cause the tissue box to collapse, and fix it after standing for 2 weeks. Sex was evaluated according to the following criteria.
The double-sided self-adhesive foam sheet was cut into 2/3 the size of the bottom of the tissue box, and the longitudinal direction of the box was the vertical direction.
○: Even if a 500 g weight is placed on the tissue box, it does not fall.
X: When a 500 g weight is placed on a tissue box, it falls.

<Peelability test of double-sided self-adhesive sheet>
The tissue box is fixed to the glass plate in the same manner as above, and after leaving for 2 weeks, the peelability between the tissue box and the double-sided self-adhesive foam sheet and the peelability between the plate glass and the double-sided self-adhesive foam sheet are as follows. evaluated.
○: The double-sided self-adhesive foam sheet was easily peeled off without breaking.
X: The double-sided self-adhesive foam sheet was destroyed.

<Repeatability test of double-sided self-adhesive sheet>
When the tissue box was fixed to a sheet glass using the double-sided self-adhesive foam sheet after the above-described peelability test, none of the examples was dropped even when a 500 g weight was placed on the tissue box.

  As described above in detail, the double-sided self-adhesive foam sheet of the present invention does not require a separate adhesive layer, so it can be peeled off without leaving the adhesive on the article or support surface, and can be reused. It is an excellent foam sheet.

Explanatory drawing of the adhesive force measuring method of a double-sided self-adhesive foam sheet. The figure which shows a mode that the storage box of the tissue paper was fixed to the plate glass.

Explanation of symbols

1 Double-sided self-adhesive foam sheet 2 Flat glass (or box paper for tissue paper storage box)
3 Tissue paper 4 Tissue paper storage box

Claims (4)

In a double-sided self-adhesive foam sheet that detachably fixes an article having at least one flat surface to a support surface such as glass, metal, plastic, paper, etc.,
The double-sided self-adhesive foam, wherein the foam sheet is an open-cell foam sheet obtained by mechanical foaming of an acrylic copolymer emulsion and has a density of 0.1 to 0.35 g / cm ³ Sheet.   The double-sided self-adhesive foam sheet according to claim 1, wherein the foam sheet has an adhesive force of 0.4 to 4N to a glass plate for mirror use.   The acrylic copolymer emulsion contains an acrylic copolymer synthesized from an acrylic ester monomer and / or a methacrylic ester monomer and a monomer having a functional group. Item 2. The double-sided self-adhesive foam sheet according to item 1. The double-sided self-adhesive foam sheet according to claim 1 or 2, wherein the acrylic copolymer emulsion contains a crosslinking agent.

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