JP2924970B2 - Adhesive sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a pressure-sensitive adhesive sheet.

[Conventional technology]

2. Description of the Related Art Conventionally, a pressure-sensitive adhesive sheet has a pressure-sensitive adhesive layer formed on one or both sides of a substrate such as paper, nonwoven fabric, fiber knitted fabric, plastic sheet, and plastic foam sheet.

[Problems to be solved by the invention]

However, in the above-mentioned conventional pressure-sensitive adhesive sheet, if the substrate is porous, the strength of the substrate is not sufficient, and the pressure-sensitive adhesive sheet may be broken when the pressure-sensitive adhesive sheet is peeled off. Therefore, when the pressure-sensitive adhesive sheet is adhered to the surface of the article and peeled off, the pressure-sensitive adhesive layer may peel off from the base material and transfer to the surface of the article to remain. In order to prevent such transfer of the adhesive, the cohesive force must be improved at the expense of the adhesive force of the adhesive layer.

[Means for solving the problem]

The present invention provides a pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer is formed on one or both surfaces of a substrate obtained by impregnating and curing a thermosetting formaldehyde resin on a porous substrate as a means for solving the above-mentioned conventional problems. is there.

 Hereinafter, the present invention will be described in detail.

(Porous substrate)

Paper, nonwoven fabric, as the porous substrate used in the present invention,
It is a porous sheet-like substrate such as a fiber knitted fabric or a plastic foam sheet having open cells. Particularly preferred among the above-mentioned substrates are nonwoven fabrics and fiber woven fabrics which are easily impregnated with a thermosetting formaldehyde resin and have high strength.

(Thermosetting formaldehyde resin)

In the present invention, the porous substrate is impregnated with a thermosetting formaldehyde resin. Examples of the formaldehyde resin include a urea resin, a melamine resin, a phenol resin, a resorcin resin, and an alkyl resorcin resin. The formaldehyde resin may be mixed in two or more forms. If desired, the formaldehyde resin may be a natural rubber, a synthetic rubber, a natural resin, a thermoplastic synthetic resin, a plasticizer, a softener, a filler, a pigment, a dye, a fungicide,
Preservatives and the like may be added.

(Manufacture of base material)

To produce the substrate of the present invention, the porous substrate is impregnated with the thermosetting formaldehyde resin. To impregnate the thermosetting formaldehyde resin into the porous substrate, the porous substrate is impregnated with the porous material. The substrate is immersed in the bath of the thermosetting formaldehyde resin, or the solution of the thermosetting formaldehyde resin is applied to the surface of the porous substrate by a spray gun, a roll coater, a knife coater, or the like. The thermosetting formaldehyde resin is impregnated into the porous substrate in an amount of about 5 to 300% by weight. The porous substrate impregnated with the thermosetting formaldehyde resin is dried, for example, by heating or by adding a catalyst to cure the impregnated formaldehyde resin. Further, when the pressure-sensitive adhesive layer is formed on one surface of the substrate of the present invention, a releasing synthetic resin such as silicon, a fluorine resin, a vinyl chloride resin, a polyethylene resin, a polypropylene resin, or a wax is formed on the other surface of the substrate. A release treatment for applying a release rubber or the like may be performed. Thus, the substrate of the present invention is obtained. The substrate of the present invention is formed into a sheet shape, a tape shape, or the like.

(Adhesive layer)

The pressure-sensitive adhesive sheet of the present invention can be obtained by applying a pressure-sensitive adhesive to one or both surfaces of the base material.

Examples of the pressure-sensitive adhesive used in the present invention include natural rubber, styrene-butadiene rubber, styrene-butadiene block copolymer, styrene-isoprene block copolymer, acrylonitrile-butadiene rubber, isoprene rubber, chloroprene rubber, butyl rubber, and polyisobutylene rubber. Latex of natural or synthetic rubber such as polybutene rubber, graft rubber, acrylate resin, methacrylate resin, vinyl acetate resin, vinyl propionate resin, vinyl acetate-ethylene copolymer resin, vinyl acetate Emulsions or latexes of maleic acid copolymer resin, styrene resin, vinyl chloride resin, vinyl chloride-ethylene copolymer resin, vinyl chloride-vinyl acetate copolymer resin, vinylidene chloride resin, polyvinyl ether resin, etc. Scan or toluene, xylene, ethyl acetate, butyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, cellosolve acetate, ethanol, isopropanol, those a solution of organic solvent butanol, shows adhesiveness at normal temperature is used. Two or more of the above natural rubbers or synthetic rubbers and synthetic resins may be mixed, and in that case, the mixture may be a mixture showing tackiness at room temperature, and each natural rubber or synthetic rubber or synthetic resin is not necessarily at room temperature. Need not be tacky. Further, a plasticizer or a softener such as dibutyl phthalate, dioctyl phthalate, tricresyl phosphate, or terpene dimer may be added to the natural rubber or the synthetic rubber or the synthetic resin. It is only necessary that the material exhibits tackiness at room temperature, and it is not necessary that each natural rubber or synthetic rubber and synthetic resin exhibit tackiness at room temperature.

Further, the pressure-sensitive adhesive of the present invention includes rosin, petroleum resin, cumarone resin, rosin derivative, terpene resin, phenolic resin, tackifiers such as alkylphenol resin, glue, gelatin, casein, starch, modified starch, oxidized starch,
Dextrin, gum arabic, sodium alginate, polyvinyl alcohol, carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, sodium polyacrylate, sodium polymethacrylate, polyacrylamide, polymethacrylamide, polyvinyl methyl ether, vinyl acetate-maleic acid copolymer, styrene −
Water-soluble polymers such as maleic acid copolymer, polyvinylpyrrolidone, partially saponified polyacrylate, partially saponified polymethacrylate, and wetting agents such as ethylene glycol, diethylene glycol, propylene glycol, glycerin, polyethylene glycol, and polypropylene glycol , Talc, bentonite, filler such as calcium carbonate and the like may be added. In addition, pigments, dyes, fungicides, preservatives and the like may be added.

The pressure-sensitive adhesive is applied normally it said porous single-sided or double-sided to the spray gun of the base material, a roll coater, at a rate of about 50 to 300 g / m ² as a normal solid by knife coater or the like, after coating is heated if desired To remove water or organic solvents. In this way, the pressure-sensitive adhesive sheet of the present invention is obtained.To obtain a tape-shaped pressure-sensitive adhesive sheet, the pressure-sensitive adhesive is applied to a sheet-shaped substrate and then cut into a tape shape, or the tape-shaped substrate is coated with a pressure-sensitive adhesive. Is applied. In the pressure-sensitive adhesive sheet of the present invention, if desired, the surface of the pressure-sensitive adhesive layer is protected by a release sheet such as a release paper, a polyethylene sheet, or a polypropylene sheet.

[Action]

When the porous base material is impregnated and cured with a thermosetting formaldehyde resin, the porous base material is reinforced and the adhesive strength with an adhesive or the like is remarkably improved.

〔The invention's effect〕

Therefore, in the present invention, a strong adhesive force can be secured without sacrificing the adhesiveness of the pressure-sensitive adhesive layer, and the transfer of the pressure-sensitive adhesive layer to the surface of the article even after being left at a high temperature for a long time is prevented. It is possible to prevent the destruction of the surface portion of the base material when the pressure-sensitive adhesive sheet is peeled off.

〔Example〕

Example 1 On one side of a tape-shaped polyester nonwoven fabric having a basis weight of 40 g / m ²
50% resole type phenol resin aqueous solution in solid
After application at an application amount of g / m ^2, the substrate was heat-treated at 170 ° C. for 10 minutes to cure the phenolic resin to form a substrate. An emulsion-type adhesive obtained by adding and mixing 10 parts by weight of a 50% aqueous starch solution to 90 parts by weight of a 50% acrylic synthetic resin emulsion was applied to one surface of the substrate at a coating amount of 150 g / m ^{2 in} terms of solid content, and dried. Thereafter, heat treatment was performed at 170 ° C. for 10 minutes to produce a single-sided adhesive tape A.

Example 2 A tape-like kraft paper having a basis weight of 30 g / m ² was immersed in a bath in which 1% ammonium chloride was added to a 50% aqueous methylated methylolmelamine solution, and the kraft paper was impregnated with the bath solution at an impregnation rate of 100%. After that, heat treatment was performed at 80 ° C. for 10 minutes to cure the methylated methylolmelamine to prepare a substrate. After applying and drying a 50% natural rubber latex-based pressure-sensitive adhesive on one surface of the base material at a coating amount of 120 g / m ^{2 in} terms of solid content,
Heat treatment was performed at 20 ° C. for 10 minutes to prepare a single-sided adhesive tape B.

Example 3 50% of 2 mm thick tape-like polyurethane foam sheet
The polyurethane foam sheet was immersed in an aqueous urea resin solution at an impregnation rate of 70% to impregnate the aqueous urea resin solution, and then heat-treated at 150 ° C. for 10 minutes to cure the urea resin to prepare a base material. A 50% butyl rubber-based pressure-sensitive adhesive toluene solution was applied to one surface of the substrate at a coating amount of 150 g / m ^{2 in} terms of solid content, and heat-treated at 150 ° C. for 5 minutes to prepare a single-sided pressure-sensitive adhesive tape C.

Comparative Examples 1-3 Polyester non-woven fabric not impregnated with a thermosetting formaldehyde resin, respectively, in place of the substrate used in Examples 1, 2, and 3,
Kraft paper, a polyurethane foam sheet was used as a base material, and the others were the same as in Examples 1, 2, and 3, except that the single-sided adhesive tape A ′,
B ′ and C ′ were created.

Comparative Example 4 Instead of the phenolic resin used in Example 1, a non-woven fabric was impregnated with a 30% toluene solution of a liquid epoxy resin: curing agent 1: 1 mixture, and heat-treated at 150 ° C. for 10 minutes to be cured. A single-sided adhesive tape A ″ was prepared in the same manner as in Example 1.

(Test) Single-sided adhesive tapes A, B, C, A ', B', C ', and A "each having a width of 25 mm and made in Examples 1, 2, 3 and Comparative Examples 1, 2, 3, and 4 above.
Is bonded to a melamine-baked coated plate, heat-treated at 180 ° C for 1 hour, and then cooled to room temperature (20 ° C).
After 180 ゜ peeling, the adhesive strength, removability and tape breakage were examined.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-58-117269 (JP, A) JP-A-56-115374 (JP, A) JP-A-57-143380 (JP, A) JP-A-2- 80479 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) C09J 7/00-7/02 B32B 27/00-27/04

Claims (1)

(57) [Claims] 1. A pressure-sensitive adhesive sheet characterized in that a pressure-sensitive adhesive layer is formed on one or both surfaces of a substrate obtained by impregnating and curing a thermosetting formaldehyde resin on a porous substrate.