JPH08199128A - Pressure-sensitive adhesive and adhesive sheets using the same - Google Patents

Abstract

PURPOSE: To obtain a pressure-sensitive adhesive exhibiting good adhesiveness to various adherends and large retaining force satisfying creep characteristics and long-term durability and providing excellent water resistance and moisture resistance. CONSTITUTION: This pressure-sensitive adhesive is obtained by using, as a base of a pressure-sensitive adhesive, a polymer emulsion obtained by subjecting a monomer comprising the following component A or the component A and the following component B to emulsion polymerization using a carboxyl group- containing polymer as a protective colloid. (A) At least one kind of a vinylalkylate-based monomer expressed by the general formula CH2 =CHOCOR (R is a 3-14C alkyl group) in an amount of 50-100wt.%. (B) A monomer, copolymerizable with the component A, in an amount of 50-0wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a pressure-sensitive adhesive based on a polymer emulsion consisting of a vinyl alkyl-based polymer, and a sheet-shaped or tape-shaped adhesive of this pressure-sensitive adhesive. The present invention relates to adhesive sheets in the form of.

[0002]

2. Description of the Related Art In recent years, pressure-sensitive adhesive sheets such as sheets and tapes have been used in place of conventional liquid pressure-sensitive adhesives for the purpose of simplifying work and improving safety and health. It has become established that adhesive treatment is performed by using. In these adhesive sheets, a pressure sensitive adhesive containing an acrylic polymer or natural rubber as a main component is used.

From the standpoint of improving the working environment, environmental protection, and effective use of resources, emulsion pressure-sensitive adhesives are used instead of solvent-type pressure-sensitive adhesives. It is being studied along with pressure-sensitive adhesives that use wire curing. This emulsion pressure-sensitive adhesive is particularly preferable because it has the advantage that the coating line applied to the solvent type can be used as it is.

[0004]

However, the one using the acrylic pressure-sensitive adhesive containing no tackifier is
Poor adhesion to plastics, especially polystyrene and polypropylene, and a pressure-sensitive adhesive containing a tackifier (acrylic / natural rubber) has relatively good adhesion to plastics, but holding power However, there was a problem in that the creep property was poor and the long-term durability was poor.
Furthermore, emulsion pressure-sensitive adhesives generally have problems of poor water resistance and moisture resistance.

In view of the above circumstances, the present invention is an emulsion type pressure-sensitive adhesive which exhibits good adhesive strength to various adherends and which is large enough to satisfy creep characteristics and long-term durability. An object of the present invention is to provide a pressure-sensitive adhesive having excellent water resistance or moisture resistance as well as holding power and its adhesive sheet.

[0006]

Means for Solving the Problems The inventors of the present invention have made extensive studies as to the above objects, and as a result, as a base for pressure-sensitive adhesives, a vinyl alkylate-based monomer was emulsified by a specific method. Obtained by polymerization, by using a polymer emulsion mainly composed of a vinyl alkyl-based polymer, good adhesion to various adherends such as polystyrene and polypropylene, and a large holding power. Then, they have found that a pressure-sensitive adhesive having excellent water resistance and moisture resistance can be obtained, and have completed the present invention.

That is, the present invention is represented by the following A component or component and B component; A) General formula (1): CH ₂ ═CHOCOR (wherein R is an alkyl group having 3 to 14 carbon atoms). 50 to 100 of at least one vinyl alkyl-based monomer
% By weight B) A polymer emulsion obtained by emulsion polymerization of a monomer consisting of 50 to 0% by weight of a monomer copolymerizable with the above-mentioned component A using a carboxyl group-containing polymer as a protective colloid. And a pressure-sensitive adhesive prepared by applying the above-mentioned pressure-sensitive adhesive to one or both sides of a support in the form of a sheet or tape. .

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The vinyl alkyl-based monomer as the component A used in the present invention has R in the general formula (1), which is an alkyl group having 3 to 14 carbon atoms, such as butyric acid, valeric acid, Caproic acid, heptanoic acid, 2-ethylhexanoic acid,
Examples thereof include vinyl esters of alkanoic acids such as octanoic acid, isooctanoic acid, capric acid, lauric acid and myristic acid. When the carbon number of R is less than 3, the initial adhesive strength is poor, and when it exceeds 14, the adhesive retention after sticking is poor, both of which are not preferable.

The vinyl alkyl monomer as the component A is 50 to 100% by weight, preferably 60 to 95% by weight, and more preferably 65 to 90% by weight, based on the total amount of the monomer. One kind or two or more kinds are used. 5
If it is less than 0% by weight, the performance as the vinyl acrylate type pressure-sensitive adhesive of the present invention cannot be exhibited.

The monomer of component B in the present invention is
Any component can be used as long as it can be copolymerized with the component A.
Vinyl alkylate in which R in the general formula (1) has less than 3 carbon atoms, such as vinyl acetate and vinyl propionate.
G-based monomer, alkyl group such as methyl group, ethyl group, propyl group, butyl group, isobutyl group, isoamyl group, hexyl group, heptyl group, 2-ethylhexyl group, isooctyl group, isononyl group, isodecyl group ( (Meth) acrylic acid ester, (meth) acrylic acid amide or a derivative thereof, styrene or a derivative thereof, N-vinyl-2-pyrrolidone, a glycidyl group-containing monomer such as glycidyl (meth) acrylate, (meth) acrylic acid 2 −
Examples thereof include hydroxyl group-containing monomers such as hydroxyethyl and 2-hydroxypropyl (meth) acrylate.

As the monomer of the component B, in addition to the above monomers, carboxyl group-containing monomers such as acrylic acid, methacrylic acid, maleic acid and fumaric acid, and other divinyl adipate, divinylbenzene and trimethylo- It is also possible to use crosslinkable monomers such as lepropane triacrylate. The B component monomer is used in an amount of 50 to 0% by weight, preferably 40 to 5% by weight, based on the total amount of the monomer, and one or more types thereof are used. Among these, the amount of the above-mentioned carboxyl group-containing monomer used is preferably 1% by weight or less based on the total amount of the monomers, and if it is more than this, there are disadvantages such as decrease in polymerization stability and polymerization rate. , Not preferable.

In the present invention, the above-mentioned component A or the monomer consisting of this and component B is emulsion polymerized. At this time, it is important to use a carboxyl group-containing polymer as a protective colloid. By using the protective colloid of (1), good results were obtained in the stability of emulsion during and after polymerization (at the time of storage or coating), and the adhesive strength and holding power desired as an emulsion pressure-sensitive adhesive were maintained. And further contributes to improvement of water resistance or moisture resistance.

The carboxyl group-containing polymer used as the protective colloid may be a substantially water-soluble polymer having a carboxyl group in the molecule, and examples thereof include vinyl ether-maleic acid copolymer and styrene- Examples thereof include maleic acid copolymers, acrylic acid-acrylic acid ester copolymers, carboxy-modified polyvinyl alcohol, carboxymethyl cellulose and the like.

The protective colloid comprising the carboxyl group-containing polymer is 0.1 to 1 per 100 parts by weight of the monomer.
It is used in an amount of 0 part by weight, preferably 0.2 to 7 parts by weight, more preferably 0.3 to 5 parts by weight. If the amount is less than 0.1 parts by weight, the stability of the polymerized emulsion is poor, and if the amount is more than 10 parts by weight, the initial adhesiveness of the pressure-sensitive adhesive is poor, so both are not preferable.

At the time of emulsion polymerization, a polymerization initiator such as potassium persulfate, ammonium persulfate, 2,2'-azobis (2-amidinopropane) dihydrochloride, an emulsifier, and, if necessary, polyvinyl alcohol, hydroxymethyl cellulose- Water-soluble polymers such as starch, hydroxyethyl cellulose and water-soluble starch may be used.

Examples of emulsifiers include nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, oxyethylene-oxypropylene block polymer, sorbitan fatty acid ester, and polyoxyethylene fatty acid. , Alkyl sulfate ester salt, alkyl benzene sulfonate, alkyl sulfosuccinate, alkyl diphenyl ether sulfonate, polyoxyethylene alkyl sulfate, polyoxyethylene alkyl phosphate, etc. To be

The pressure-sensitive adhesive of the present invention is based on a polymer emulsion mainly composed of the above-mentioned vinyl alkylate type polymer obtained by emulsion polymerization. If necessary, an external cross-linking agent usually used in pressure-sensitive adhesives and, as additives, for example, fillers such as glass fiber and metal powder, pigments, colorants and the like can be added.

The adhesive sheet of the present invention is prepared by applying a pressure-sensitive adhesive containing such a polymer emulsion as a base on one side or both sides of the support to form a sheet or tape. It is in the form of a shape. Here, as the support, for example,
Plastic film, paper, non-woven fabric, foam, metal foil and the like are used, and one or both of which may be subjected to a release treatment or an adhesive treatment may also be used.

[0019]

EFFECTS OF THE INVENTION According to the present invention, while exhibiting good adhesion to various adherends, a large holding power satisfying creep characteristics and long-term durability, and excellent water resistance or A pressure sensitive adhesive having moisture resistance and its adhesive sheet can be provided.

[0020]

EXAMPLES Next, examples of the present invention will be described to more specifically describe. In the following, "parts" means "parts by weight".

Example 1 60 parts of vinyl laurate, 20 parts of vinyl butyrate, 20 parts of vinyl acetate and 2,2'-as a polymerization initiator were placed in a reaction vessel equipped with a cooling pipe, a nitrogen introducing pipe, a thermometer and a stirrer. Azobis (2-amidinopropane) dihydrochloride 0.1
Parts, 0.5 parts of polyoxyethylene nonylphenyl ether as an emulsifier, methyl vinyl ether as a protective colloid
Add 1 part of ter-maleic acid copolymer and 100 parts of water, and
The pH was adjusted to 8 with 0% by weight aqueous ammonia, and then emulsion polymerization was performed.

The polymer emulsion thus obtained was used as a pressure-sensitive adhesive, and this was coated on one side of a polyester film having a thickness of 38 μm so that the thickness after drying was 50 μm, and at 120 ° C. It was dried for 3 minutes to prepare an adhesive tape.

Example 2 75 parts of vinyl 2-ethylhexanoate, 5 parts of n-butyl acrylate, 20 parts of vinyl acetate and a polymerization initiator were placed in a reaction vessel equipped with a cooling pipe, a nitrogen introducing pipe, a thermometer and a stirrer. As an emulsifier, 0.3 part of potassium persulfate, 0.5 part of sodium dodecylbenzene sulfonate, 2 parts of styrene-maleic acid copolymer as a protective colloid, and 100 parts of water are added.
The pH was adjusted to 8 with 0% by weight aqueous ammonia, and then emulsion polymerization was performed. Using the obtained polymer emulsion as a pressure sensitive adhesive, an adhesive tape was manufactured in the same manner as in Example 1 below.

Example 3 80 parts of vinyl 2-ethylhexanoate, 15 parts of vinyl acetate, 4.8 parts of ethyl acrylate, divinyl adipate were placed in a reaction vessel equipped with a cooling pipe, a nitrogen introducing pipe, a thermometer and a stirrer. 0.2 part, 2,2′-azobis (2
-Amidinopropane) dihydrochloride 0.2 part, sodium dodecylbenzene sulfonate as emulsifier 0.5
Parts, 3 parts of carboxy-modified polyvinyl alcohol as a protective colloid, and 100 parts of water were added, and the pH was adjusted to 8 with 10% by weight ammonia water, followed by emulsion polymerization. Using the obtained polymer emulsion as a pressure sensitive adhesive, an adhesive tape was manufactured in the same manner as in Example 1 below.

Example 4 To the polymer emulsion obtained in Example 1, 1 part of hexamethylolmelamine as a cross-linking agent was added to 100 parts of solid content of emulsion to obtain a pressure-sensitive adhesive. Using this pressure-sensitive adhesive, an adhesive tape was prepared in the same manner as in Example 1.

Comparative Example 1 A polymer emulsion was obtained in the same manner as in Example 1 except that 40 parts of vinyl laurate, 45 parts of ethyl acrylate and 15 parts of vinyl acetate were used as the monomers. Using this as a pressure sensitive adhesive, an adhesive tape was prepared in the same manner as in Example 1.

Comparative Example 2 A polymer emulsion was obtained in the same manner as in Example 1 except that 1 part of the methyl vinyl ether-maleic acid copolymer as a protective colloid was removed. Using this as a pressure sensitive adhesive, an adhesive tape was prepared in the same manner as in Example 1.

Comparative Example 3 A polymer emulsion was obtained in the same manner as in Example 1 except that the amount of methyl vinyl ether-maleic acid copolymer used as a protective colloid was changed to 15 parts. Using this as a pressure sensitive adhesive, an adhesive tape was prepared in the same manner as in Example 1.

Comparative Example 4 A polymer emulsion was obtained in the same manner as in Example 1 except that 1 part of polyvinyl alcohol was used in place of 1 part of the methyl vinyl ether-maleic acid copolymer as a protective colloid. It was Using this as a pressure sensitive adhesive, an adhesive tape was prepared in the same manner as in Example 1.

With respect to the adhesive tapes of Examples 1 to 4 and Comparative Examples 1 to 4 described above, the adhesive strength, the holding power and the moisture resistance were examined by the following procedures. The results are shown in Table 1 below.

<Adhesive strength> An adhesive tape of 20 mm × 100 mm is pressure-bonded to the adherend by reciprocating a 2 kg roller once and left at 23 ° C. × 20 minutes and 70 ° C. × 48 hours. After that, the 180 ° peel adhesive strength was measured at a pulling rate of 300 mm / min in an environment of 23 ° C. and 65% RH. As the adherend, a stainless plate (SUS430BA), polystyrene plate, or polypropylene plate was used. In Table 1,
"A" is a stainless steel plate, "B" is a polystyrene plate,
"C" is a polypropylene plate.

<Holding power> An adhesive tape having a width of 10 mm was attached to a phenol resin plate with an adhesive area of 10 mm × 20 mm, and after 20 minutes, it was allowed to stand at 80 ° C. for 20 minutes, and then put into a phenol resin plate.
The resin resin plate was hung down, a uniform load of 500 g was applied to the free end of the adhesive tape, and the drop time (minute) of the adhesive tape at 80 ° C. and the shift distance (mm) after 120 minutes were measured. .

<Moisture resistance> An adhesive tape having a width of 10 mm is attached to a phenol resin plate with an adhesive area of 10 mm × 20 mm, and after 20 minutes, left at 60 ° C. and 95% RH for 20 minutes. , A phenol resin plate is hung down, a uniform load of 500 g is applied to the free end of the adhesive tape, the adhesive tape drop time at 60 ° C, 95% RH, and the deviation distance after 120 minutes (mm ) Was measured.

[0034]

[Table 1]

From the results of Table 1 above, Example 1 of the present invention
It is clear that the adhesive tapes Nos. 4 to 4 have good adhesive strength to various adherends, have a large holding power, and are extremely excellent in terms of moisture resistance. .

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Waka Hikosaka 1-2-1, Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation

Claims (3)

[Claims] 1. A component or the following B component; A) at least one of general formula (1): CH ₂ ═CHOCOR (wherein R is an alkyl group having 3 to 14 carbon atoms); Vinyl alkylate type monomer 50-100
% By weight B) A polymer emulsion obtained by emulsion polymerization of a monomer consisting of 50 to 0% by weight of a monomer copolymerizable with the above-mentioned component A using a carboxyl group-containing polymer as a protective colloid. Pressure sensitive adhesive. 2. The pressure sensitive adhesive according to claim 1, wherein the carboxyl group-containing polymer as a protective colloid is 0.1 to 10 parts by weight with respect to 100 parts by weight of the monomer. 3. Adhesive sheets prepared by coating the pressure-sensitive adhesive according to claim 1 or 2 on one side or both sides of a support.