JPH06100848A - Heat-sensitive delayed tack adhesive and heat-sensitive adhesive sheet - Google Patents

Abstract

(57) [Summary] [Purpose] It is an object of the present invention to provide a heat-sensitive delayed tack-type pressure-sensitive adhesive having excellent blocking resistance and adhesive properties. [Structure] A heat-sensitive delayed tack type pressure-sensitive adhesive containing a thermoplastic resin, a tackifier, a crystalline plasticizer and a colloid, and a heat-sensitive pressure-sensitive adhesive sheet obtained by applying the heat-sensitive delayed tack type pressure-sensitive adhesive to a substrate. According to the present invention, compared with a pressure-sensitive adhesive sheet obtained by coating a conventional heat-sensitive delayed-tack type pressure-sensitive adhesive, blocking resistance is improved and pressure-sensitive adhesive development time is not prolonged,
A pressure-sensitive adhesive sheet that can satisfy practical properties in terms of adhesive strength and holding power has been obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is non-tacky at room temperature but develops tackiness upon heating, and
The present invention relates to a heat-sensitive delayed tack type pressure-sensitive adhesive and a heat-sensitive pressure-sensitive adhesive sheet, which retain their tackiness for a while even after removing the heating source.

[0002]

2. Description of the Related Art Conventional heat-sensitive delayed tack adhesives have a composition of a thermoplastic resin, as described in "Adhesion Handbook" (12th edition, 1980, published by Kobunshi Kogyo Kai). It has a tackifier and a crystalline plasticizer as a basic skeleton. Thermoplastic resins are the source of tackiness and adhesiveness. Further, since the crystalline plasticizer is solid at room temperature, it does not give plasticity to the resin, and it melts by heating to swell or soften the resin, so that it becomes a non-tacky adhesive at room temperature,
When heated, it acts to develop tackiness.
At this time, when the tackifier is present, the tackiness becomes more remarkable, and the practical properties are improved.

However, since the crystalline plasticizer softens to some extent to give plasticity to the resin even under the melting point or below depending on conditions such as storage temperature, there is a problem in terms of blocking resistance.

Therefore, for the purpose of improving the blocking resistance, a heat-sensitive adhesive containing an ethylene-vinyl acetate copolymer, a tackifying resin, a crystalline plasticizer and a wax is disclosed in Japanese Patent Publication No. 62-21835. It is disclosed. However, the blocking resistance is insufficient only with the wax added for the purpose of suppressing the tackiness at room temperature. Further, in order to improve the blocking resistance, when coating a heat-sensitive adhesive on a sheet, a method of setting the smoothness of the coated surface within a certain numerical range is disclosed in JP-A-63-172784. It is practically difficult to control the smoothness of the coated surface as described. Further, a method of adding or mixing an inorganic substance is disclosed in Japanese Patent Application Laid-Open No. 2-282050, but simply adding an ordinary inorganic substance is not sufficient.

That is, the conventional heat-sensitive delayed tack adhesive has 1) poor blocking resistance and poor blocking resistance. Therefore, a heat-sensitive adhesive sheet prepared by applying a heat-sensitive delayed tack adhesive is prepared. There is a risk that the heat-sensitive delayed-tack type pressure-sensitive adhesive contact surface will stick when the rolls are stored in a rolled state. 2) The improvement of 1) has a drawback that the adhesive force or the holding force is lowered.

[0006]

DISCLOSURE OF THE INVENTION The present inventors have conducted extensive studies to overcome the above-mentioned drawbacks, and as a result, by incorporating a colloid, a heat-sensitive delayed tack type adhesive having excellent blocking resistance and adhesive properties. The inventors have found that an agent can be obtained, and completed the present invention.

[0007]

That is, the present invention provides a heat-sensitive delayed tack type adhesive containing a thermoplastic resin, a tackifier, a crystalline plasticizer and a colloid, and a base of the heat sensitive delayed tack type adhesive. There is provided a heat-sensitive adhesive sheet which is applied to the.

The colloidal particles have a very small particle size as compared with ordinary inorganic or organic substances, and when they are contained in the adhesive, the dispersed state is stable, so that the surroundings of the crystalline plasticizer are protected. It is considered that the softening of the crystalline plasticizer is suppressed and the blocking resistance is improved.

As the colloid, depending on the compatibility with the thermoplastic resin, tackifier or crystalline plasticizer used in the heat-sensitive delayed tack type adhesive, cost, etc.,
It may be selected appropriately. Examples thereof include molecular colloids such as proteins and elastic rubbers, micelle colloids formed from soaps and the like, particle colloids such as oxide sols and metal sols, and the particle colloids are suitable for improving blocking resistance.

There are various kinds of particle colloids depending on the combination of the dispersoid and the dispersion state of the dispersion medium. Examples of the oxide sol include colloidal silica, alumina sol, antimony oxide sol and zirconia sol. Examples of the metal sol include gold sol and selenium sol. Further, smectite and the like, which are fine clay minerals and become a sol when dispersed in water or the like, can be mentioned. The colloid may be added and / or mixed either during mixing or during mixing and dispersion after mixing and dispersing the thermoplastic resin, tackifier and crystalline plasticizer, and further, a part thereof may be added and / or mixed during the mixing and / or mixing. You may mix.

Examples of the crystalline plasticizer include diphenyl phthalate, dihexyl phthalate, dicyclohexyl phthalate, dihydroabietyl phthalate, dimethyl isophthalate, sucrose benzoate, ethylene glycol dibenzoate, tribenzoic acid. Examples thereof include trimethylolethane, tribenzoic acid glyceride, tetrabenzoic acid pentaerythritol, sucrose octaacetate, tricyclohexyl citrate, and N-cyclohexyl-p-toluenesulfonamide, with dicyclohexyl phthalate being preferred.

Examples of the thermoplastic resin include acrylic acid ester, styrene-acrylic acid ester, styrene-
Butadiene, ethylene-vinyl acetate, vinyl acetate, vinyl acetate-acrylic acid ester, ethylene-vinyl chloride,
Examples thereof include polymers such as ethylene-acrylic acid ester, ethylene-acrylic acid, polybutadiene, urethane, and styrene-isoprene block polymer.

Further, as the tackifier for improving the tack performance of the tackifier, for example, terpene resin, aliphatic petroleum resin, aromatic petroleum resin, coumarone-indene resin, styrene resin, phenol resin, terpene. -Phenol resin and rosin derivatives (rosin, polymerized rosin, hydrogenated rosin and their esters with glycerin, pentaerythritol, etc., resin acid dimer, etc.).

The above-mentioned crystalline plasticizer, thermoplastic resin, tackifier or colloid can be used alone or as a mixture of two or more kinds. In addition to this, in the heat-sensitive delayed tack type adhesive of the present invention, a filler or the like can be added within a range not hindering the object of the present invention, for example, an inorganic substance such as titanium oxide, alumina, kaolin or talc,
Organic substances such as paraffin, natural wax, synthetic wax, natural oil and fat, and resin powder can also be used. Furthermore, if necessary, a dispersant, a defoaming agent, a thickener, or the like can be used. The heat-sensitive delayed tack-type pressure-sensitive adhesive of the present invention can be applied to a substrate as an aqueous emulsion or an organic solvent solution to give a heat-sensitive pressure-sensitive adhesive sheet.

[0015]

EXAMPLES The present invention will be specifically described below with reference to examples. However, the scope of the present invention is not limited to the following examples. In the examples, “part” means “part by weight”,
% Represents% by weight. Examples 1 to 7 and Comparative Examples 1 to 4 Adhesives were prepared by mixing the compositions shown in Table 1 with a mixer. In addition,
In Example 1, half amount of colloidal silica (80 parts)
After adding and mixing, half the amount of colloidal silica (80
Part) was added and mixed. Further, in Example 7, smectite was mixed with water in advance and then mixed with other components. The obtained pressure-sensitive adhesive was directly coated on a single-sided art paper so that the coating amount was 20 g / m ^2, and dried at 40 ° C. for 2 minutes. No tackiness could be confirmed in the dried state. Table 1 shows the results of evaluation of the adhesive force, the holding force and the blocking property of the coated article.

[0016]

[Table 1] * 1 Ethylene-vinyl acetate copolymer * 2 Styrene-butadiene copolymer * 3 Powder, which becomes a colloidal solution when dispersed.

The adhesive strength, holding power and blocking property of the coated product were evaluated by the following methods. Adhesion: Heat the coating at 120 ° C for 25 seconds to develop its adhesiveness, and then quickly attach it to the stainless steel plate, and
Measure the adhesive strength by peeling 180 degrees according to S K-6848,
It was judged according to the following criteria. However, the glued part was 100 mm. ◎ ・ ・ 1200g / 25mm or more ○ ・ ・ ・ ・ ・ ・ 1000g / 25mm or more, less than 1200g / 25mm × ・ ・ ・ ・ ・ ・ less than 1000g / 25mm

Holding power; after the appearance of tackiness by heating,
Quickly attach the adhesive coating to the stainless steel plate, and
A creep test was performed according to SK-6848 and judged according to the following criteria. However, the glued part was 25 mm. ◎ ・ ・ 2000sec or more ○ ・ ・ ・ ・ ・ ・ 1000sec or more, less than 2000sec × ・ ・ ・ ・ ・ ・ less than 1000sec

Blocking property: 1000 g / c for adhesive coating
After applying a load of m ² and storing at 50 ° C. for 1 hour, it was peeled off and judged according to the following criteria. ◎ ・ ・ ・ ・ ・ ・ No peeling resistance. ○ ・ ・ ・ ・ ・ ・ A slight noise is heard when peeling. × ・ ・ ・ ・ ・ ・ Pull fiber of paper when peeling.

[0020]

According to the present invention, as compared with a pressure-sensitive adhesive sheet obtained by coating a conventional heat-sensitive delayed tack type pressure-sensitive adhesive,
It has become possible to obtain a pressure-sensitive adhesive sheet that has improved blocking resistance, does not require a long time for the pressure-sensitive adhesiveness to develop, and has practical adhesive properties and holding power. The industrial significance of being able to pursue resource-saving and economical benefits as labels, tapes, seals for packages, etc. that do not require release paper is extremely great.

Front page continuation (72) Inventor Yasuhito Kuwahara 2-3-13 Kyobashi, Chuo-ku, Tokyo Toyo Inn Co., Ltd. (72) Hiroyuki Iida 2-3-13 Kyobashi, Chuo-ku, Tokyo Toyo Inn Ki Manufacturing Co., Ltd.

Claims (4)

[Claims] 1. A heat-sensitive delayed tack type pressure-sensitive adhesive containing a thermoplastic resin, a tackifier, a crystalline plasticizer and a colloid. 2. The heat-sensitive delayed tack type pressure-sensitive adhesive according to claim 1, wherein the colloid is an oxide sol. 3. The heat-sensitive delayed tack-type pressure-sensitive adhesive according to claim 1, wherein the colloid is colloidal silica. 4. A heat-sensitive pressure-sensitive adhesive sheet obtained by applying the heat-sensitive delayed tack type pressure-sensitive adhesive according to claim 1 to a substrate.