JPH0657233A - Heat-sensitive delayed tack adhesive - Google Patents

Abstract

(57) [Summary] [Purpose] It is an object of the present invention to provide a heat-sensitive delayed tack type adhesive having excellent adhesive properties and blocking resistance. [Structure] A heat-sensitive delayed tack type pressure-sensitive adhesive containing a thermoplastic resin having a glass transition temperature of -5 ° C or higher (excluding ethylene-vinyl acetate copolymer), a crystalline plasticizer and a tackifier. [Effects] According to the present invention, a heat-sensitive delayed tack type adhesive having excellent blocking resistance while having a good balance of adhesive strength and holding power was obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive delayed tack type pressure-sensitive adhesive which is non-tacky at room temperature but is activated by heating and has a long-term tackiness even after the heat source is removed.

[0002]

2. Description of the Related Art A heat-sensitive delayed tack type adhesive is
"Handbook of Adhesion" (12th edition, 1980, published by Kobunshi Publishing Association)
As described in the concrete example, it basically contains a thermoplastic resin, a crystalline plasticizer which is solid at room temperature, and a tackifier. Thermoplastic resins are the source of tackiness and adhesiveness, and crystalline plasticizers are solid at room temperature and do not give plasticity to the resin, but they are melted by heating to swell or soften the resin And the tackifier functions to improve the tackiness. The crystalline plasticizer in the heat-sensitive delayed tack type adhesive slowly crystallizes after being melted by heating, so that the adhesiveness is maintained for a long time. However, the adhesive strength after the appearance of adhesiveness was not sufficient. Therefore, as disclosed in JP-A-63-172784, the glass transition temperature (Tg) is from -20 ° C to -40 ° C.
Thermoplastic resins of about ℃ have come to be used. A thermoplastic resin having Tg of about -20 ° C to -40 ° C has excellent adhesive strength and adhesive strength because it has adhesiveness by itself, but on the other hand, since it is soft, it has holding power and blocking resistance. It was remarkably inferior and had practical problems.

That is, in the conventional heat-sensitive delayed tack type adhesive, 1) blocking occurs, an adhesive produced by using a thermoplastic resin having a low Tg or a crystalline plasticizer having a low melting point is Blocking may occur due to pressure or high temperature when applied to a substrate and wound after being dried, or when being stacked and stored. 2) It is difficult to improve the adhesive force and the holding force in a well-balanced manner, and the adhesive force and the holding force, which are important functions of the pressure-sensitive adhesive, are mutually opposite properties. However, if the holding power is improved, the adhesive strength will be reduced. There is a problem.

[0004]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted diligent research to solve these problems, and as a result, by using a thermoplastic resin having a glass transition temperature of -5 ° C. or higher, blocking resistance can be improved. It was found that a heat-sensitive delayed tack type adhesive having excellent adhesive properties was obtained, and the present invention was completed. INDUSTRIAL APPLICABILITY The present invention makes a thermoplastic resin that cannot be used because it is hard at room temperature hard, tacky, and poor in adhesiveness by making use of the plasticizing effect of the crystalline plasticizer, and the resulting heat-sensitive delayed tack adhesive It is intended to improve the holding power and blocking resistance of the agent.
It is considered that the hardness of the resin contributes to the improvement of the blocking resistance.

[0005]

[Means for Solving the Problems] That is, the present invention provides a thermoplastic resin having a glass transition temperature (Tg) of −5 ° C. or higher (excluding ethylene-vinyl acetate copolymer), a crystalline plasticizer and a tackifier. A heat-sensitive delayed tack type pressure-sensitive adhesive characterized by being used. Examples of the thermoplastic resin having Tg of −5 ° C. or higher which can be used in the present invention include acrylic acid ester, styrene-acrylic acid ester, styrene-butadiene, vinyl acetate, vinyl acetate-acrylic acid ester, ethylene-vinyl chloride, Examples thereof include ethylene-acrylic acid ester, polybutadiene, urethane, and styrene-isoprene block polymer, but the ethylene-vinyl acetate copolymer is not limited thereto. These can be used alone or as a mixture of two or more as an aqueous emulsion or an organic solvent solution.

Crystalline plasticizers that can be used to plasticize the above thermoplastic resins include diphenyl phthalate, dihexyl phthalate, dicyclohexyl phthalate, dihydroabietyl phthalate, dimethyl isophthalate, and sucrose benzoate. -Su, ethylene glycol dibenzoate-
And tritrimethylene tribenzoate, triglyceride tribenzoate, pentaerythritol tetrabenzoate, sucrose octaacetate, tricyclohexyl citrate, N-cyclohexyl-p-toluenesulfonamide, etc. High dicyclohexyl phthalate is preferred.

Further, as the tackifying resin which can be used for improving the tackiness of the tackiness agent, terpene resin, aliphatic petroleum resin, aromatic petroleum resin, coumarone-indene resin, styrene resin, Examples thereof include a phenol resin, a terpene-phenol resin, and a rosin derivative (rosin, polymerized rosin, hydrogenated rosin and esters thereof with glycerin, pentaerythritol, etc., resin acid dimer, etc.). However, in order to improve the blocking resistance, a resin having a high softening point is preferable. These can be used as an aqueous emulsion or an organic solvent solution. In addition, inorganic substances such as titanium oxide, alumina, colloidal silica, kaolin, and talc, and organic substances such as paraffin, natural wax, synthetic wax, natural fats and oils, and styrene as an additive for blocking prevention are also required. Depending on the case, a dispersant, a defoaming agent, a thickener and the like can also be used.

[0008]

EXAMPLES The present invention will be described in detail below with reference to examples, but these examples do not limit the present invention. In the following Examples and Comparative Examples, “part” means part by weight unless otherwise specified. Further, the adhesive strength, the holding power, and the blocking property in Examples and Comparative Examples are
It evaluated by the following methods. Adhesion: After thermal activation of the coating, quickly attach it to a stainless steel plate, leave it for 20 minutes, and then in accordance with JIS K-6848.
The adhesive strength was measured by peeling 180 degrees, and judged according to the following criteria. ○ ・ ・ ・ 1000g / 25mm or more × ・ ・ ・ 1000g / 25mm or less

Holding power: After heat-activating the coating, it is immediately attached to a stainless steel plate and allowed to stand for 20 minutes. JIS K-6
The creep test was conducted according to 848 and judged according to the following criteria. ◎ ・ ・ ・ 3000sec or more ○ ・ ・ ・ 2000sec or more, less than 3000sec △ ・ ・ ・ 1000sec or more, less than 2000sec × ・ ・ ・ less than 1000sec Blocking property: A load of 500g / cm ² is applied to the coated material at each temperature. It was peeled off after being left for 1 hour, and judged according to the following criteria. 5 ... No peeling resistance 4 ... Slight noise during peeling 3 ... Continuous sound during peeling 2 ... Pull fiber of paper during peeling 1 ... Tear paper due to blocking 0 ... Complete adhesion (cannot be peeled off)

Example 1 Dicyclohexyl phthalate 3
16 parts, maleic acid resin solution (solid content 30%) 53 parts, water 1
22 parts, Tg-5 ° C acrylic resin emulsion (solid content
50%) 184 parts and rosin ester-based tackifier emulsion (solid content 50%) 158 parts were mixed to obtain a heat-sensitive delay.
A tack type adhesive was prepared. [Example 2] 316 parts of diphenyl phthalate, 53 parts of maleic acid resin solution (solid content 30%), 122 parts of water, styrene-butadiene rubber emulsion having Tg of 5 ° C (solid content 50%) 1
84 parts and 158 parts of rosin ester-based tackifier emulsion (solid content 50%) were mixed to prepare a heat-sensitive delayed tack-type adhesive.

Comparative Example 1 Dicyclohexyl phthalate 3
16 parts, maleic acid resin solution (solid content 30%) 53 parts, water 1
22 parts, Tg-20 ° C ethylene-vinyl acetate-acrylic copolymer emulsion (solid content 50%) 184 parts and rosin ester tackifier emulsion (solid content 50%) 158 parts were mixed to obtain a heat-sensitive delay. A tack type adhesive was prepared. The adhesive emulsion prepared by the above method is applied on one side.
The coated paper was coated at 20 g / m ² and dried at 40 ° C. for 2 minutes. It was non-adhesive in this state. Table 1 shows the results of evaluation of the adhesive strength, holding power and blocking of the coated article. The adhesive force and the holding force were evaluated at 120 ° C. for 25 seconds after thermally activating the coated product.

[0012]

[Table 1]

[0013]

As a result of the present invention, the adhesive strength is not inferior to the conventional heat-sensitive delayed tack type adhesive, and the holding power,
A pressure-sensitive adhesive having good blocking resistance could be obtained.

Front Page Continuation (72) Inventor Yasuhito Kuwahara 2-3-13 Kyobashi, Chuo-ku, Tokyo Toyo Inki Manufacturing Co., Ltd.

Claims (1)

[Claims] 1. A thermosensitive delayed tack type comprising a thermoplastic resin having a glass transition temperature of −5 ° C. or higher (excluding ethylene-vinyl acetate copolymer), a crystalline plasticizer and a tackifier. Adhesive.