JPH064827B2 - Adhesive tape manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an adhesive tape,
More specifically, in an adhesive tape made of a porous base material having a coating layer formed on one surface, the adhesive layer is heated to vaporize and foam the volatile substance in the base material to form innumerable minute closed cells in the adhesive layer. The present invention provides a method for producing an adhesive tape.

Conventionally, an adhesive tape having closed cells in the adhesive layer is known, but the formation of the bubbles in the tape is performed by adding a heat-decomposable foaming agent in advance to the adhesive composition and then heating and foaming. I am doing it. When bubbles are formed by such a method, innumerable crater-like bubble rupture marks are often formed on the surface layer of the adhesive layer.

As described above, when crater-like bubble rupture marks are formed in the surface layer portion of the adhesive layer, the target adhesive force cannot be obtained because the effective adhesive area with the adherend is insufficient. is there.

As a method for improving the above-mentioned drawbacks, the present inventors provided an adhesive layer on a substrate containing a volatile substance without using a heat-decomposable foaming agent, and heated the adhesive layer to vaporize it. We have invented a method of vaporizing and foaming a substance to form a myriad of closed cells in the adhesive layer, and have already filed a patent application.

According to the invention, the crater-like bubble rupture traces are not formed on the surface layer portion of the adhesive layer, and innumerable closed cells are formed in the adhesive layer. It was found that since the substance is vaporized from the opposite surface of the adhesive layer, that is, the exposed surface of the porous substrate, the foaming efficiency is poor and the expansion ratio is limited.

As a result of further earnest studies, the present inventors have found a method for efficiently vaporizing and foaming a volatile substance contained in a base material into an adhesive layer, and arrived at the present invention.

That is, the present invention, on one surface of the porous substrate containing a volatile substance,
A coating layer having a softening point that is at least 5 ° C. higher than the boiling point of the substance is provided, and an adhesive layer is provided on the other surface, and the adhesive layer and the base material are heated so that innumerable minute closed cells are formed in the adhesive layer. The present invention provides a method for manufacturing an adhesive tape to be formed.

According to the method of the present invention, innumerable minute closed cells can be efficiently formed on the entire surface or a desired place in the adhesive layer of the adhesive tape.

The vaporizable substance used in the practice of the present invention is water or a substance selected from the group of organic solvents such as ethyl acetate, toluene and alcohol, and the porous substrate is paper, woven fabric, non-woven fabric, The vaporizable substance, such as felt or porous plastic film, may be evenly or partially about 2-30.
It is a material that can be contained in a weight percentage.

The coating layer is formed on one surface of the porous substrate by laminating or superimposing a thermoplastic resin such as polyethylene, polypropylene or acrylic resin, or an impermeable thin sheet material such as metal foil. Therefore, in using the resins in the practice of the present invention, it is necessary to select a resin having a Vicat softening point which is at least 5 ° C. higher than the boiling point of the vaporizable substance. When water is used as the substance, at the softening point of 105 ° C. or less, when the adhesive layer and the base material made of the pressure sensitive adhesive composition mainly composed of rubber and / or synthetic resin are heated, the coating layer also softens and vaporizes. Since a volatile substance vaporizes and foams even in the coating layer, a substance having a softening degree at least 5 ° C. higher than that of the substance is used. Further, when the coating layer is made of the above resins and has a small thickness, the barrier function of the coating layer is low, and thus crater-like bubble rupture marks may be formed in the surface layer portion, so that the thickness of the coating layer is 5 μm. Or more, preferably 10 μm
The above is preferable. If a metal foil is used, one without pinholes is selected, and one having a melting point much higher than the boiling point of the vaporizable substance is used.

Generally, since the adhesive tape is wound in a roll and used, a release layer made of a silicone resin or the like is provided on the back surface (coating layer surface) of the base material.

According to the adhesive tape obtained by the production method of the present invention, since a large number of independent microscopic bubbles are formed in the adhesive layer, it has cushioning properties, and has good holding performance following the deformation of the adherend. It has a removable property that can be removed without damaging the surface of paper materials such as corrugated cardboard, and the bubbles do not collapse over time.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to the following examples.

Example 1 One side of kraft paper has a melt index (hereinafter referred to as MI) of 8.0 dg / min, a density of 0.919 g / cm ³ , and a Vicat softening point of 87.
A low-density polyethylene (hereinafter referred to as LDPE) having a film thickness of 15 μm was laminated under ordinary extrusion conditions to prepare a tape base material. About 10% by weight of ethyl methyl ketone (hereafter MEK) with a boiling point of 80 ° C is added to this base material.
Included.

On the other hand, 100 parts by weight of styrene-isoprene-styrene block copolymer (hereinafter referred to as "part"), petroleum-based resin 100
Parts, and an adhesive composition consisting of 1 part of an antioxidant are obtained.

The composition was applied to the surface of the base material opposite to the coating layer with a thickness of 30 μm.
It was melt-coated so as to be m.

Then heat the tape in a dryer at 85 ° C for 10 minutes,
An adhesive tape having innumerable minute closed cells in the adhesive layer was obtained.

Comparative Example 1 In Example 1, L having a Vicat softening point of 81 ° C. was used instead of LDPE.
An adhesive tape was obtained in the same manner as in Example 1 except that DPE was used.

Comparative Example 2 An adhesive tape was obtained in the same manner as in Example 1 using kraft paper on which LDPE was not laminated. Table 1 shows the measurement results of Example 1 and Comparative Examples 1 to 3.

Example 2 Polypropylene (hereinafter referred to as PP) having MI 24 dg / min, density 0.90 g / cm ³ , Vicat softening point 151 ° C., and heat distortion temperature 105 ° C. was laminated on kraft paper to a thickness of 25 μm under a usual extrusion condition, Further, a base material having a silicone-based releasable treatment layer provided on the layer was prepared.

An adhesive layer was provided on the base material in the same manner as in Example 1, the tape roll was wound in a roll shape and cut into a width of 50 mm.
The kraft paper is stored in an atmosphere of ℃ × 90% RH for 50 hours to retain about 8% by weight of water.

This was heated at 103 ° C. for 4 minutes to obtain a tape having an adhesive layer having innumerable closed cells in the adhesive layer.

Comparative Example 3 In Example 2, MI 20 dg / min, density 0.90 g / cm ³ , Vic
PP with a softening point of 131 ° C and a heat distortion temperature of 90 ° C
An adhesive tape was obtained in the same manner as in Example 2 except that 8090 Chisso Corporation was used.

Comparative Example 4 An adhesive tape was obtained in the same manner as in Example 2 except that PP was not laminated and a kraft substrate provided with only a release layer was used.

Table 2 shows the side determination results of Example 2 and Comparative Examples 3-4.

Claims (1)

[Claims] 1. A porous base material containing a vaporizable substance is provided with a coating layer having a softening point at least 5 ° C. higher than the boiling point of the substance on one side and an adhesive layer on the other side. A method for producing an adhesive tape, which comprises heating a base material to form innumerable minute closed cells in the adhesive layer.