JPH09310049A - Production of adhesive tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently produce an adhesive tape capable of reducing a penetration of an adhesive by coating a liquid having no compatibility with the hot melt adhesive on a porous base material and overcoating the coated surface with the hot melt adhesive consisting essentially of a thermoplastic block copolymer rubber. SOLUTION: A liquid having no compatibility with a hot melt adhesive (e.g. water, glycerol, ethylene glycol, etc., preferably, having <=100 deg.C boiling point) is coated on a porous base material and a hot melt adhesive consisting essentially of a thermoplastic block copolymer rubber is overcoated on the coated surface to from an adhesive layer. Moreover, the coating amount of the liquid having no compatibility with the hot melt adhesive is preferably 0.1-30g/m<2> . A kraft paper, a woven fabric, a nonwoven fabric, etc., are exemplified as the porous base material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a pressure-sensitive adhesive tape, which can prevent the hot-melt pressure-sensitive adhesive applied to a substrate from seeping into the substrate and can efficiently manufacture the pressure-sensitive adhesive tape. Regarding the method.

[0002]

2. Description of the Related Art Conventionally, a method for producing an adhesive tape comprising a hot-melt adhesive layer formed on a porous substrate has a back surface coated with polyethylene, and the laminated surface is subjected to a release treatment. (Wet Strengthening) A natural rubber-based adhesive or a synthetic rubber-based adhesive is directly hot-melt applied onto the surface of a kraft paper having a Clupak process or the surface of a woven fabric subjected to the same back treatment.

According to the above-mentioned conventional method for producing an adhesive tape using a hot-melt adhesive, the molten hot-melt adhesive penetrates into the fibers of kraft paper or woven fabric to form an applied adhesive. It becomes thinner than the designed thickness, and the required adhesive strength cannot be obtained. Therefore, in order to obtain the adhesive strength as designed, it is wasteful that an excessive amount of adhesive must be applied.

There is also known a method in which a pressure-sensitive adhesive is applied to release-processed process paper to form a pressure-sensitive adhesive layer, and then the pressure-sensitive adhesive layer is transferred to a substrate. The production speed is slower and productivity is lower than the coating method. Further, since the process paper is used several times and then discarded, the cost becomes high. Furthermore, in the case of a hot-melt adhesive, the adhesive strength between the transferred adhesive layer and the substrate is often insufficient, and the peeling force of the long-chain alkyl type release agent on the back surface of the substrate is relatively large. When a wound body is formed by using a release agent, there is a problem that it is difficult to develop and the base material and the pressure-sensitive adhesive layer are separated from each other.

By the way, in Japanese Patent Publication No. 60-18564, a sealing layer for a release agent is formed by applying an alcohol solution of polyvinyl acetate hydrolyzate to kraft paper as a base material of an adhesive tape and drying it. The method is described.

The sealing layer described in the above publication is for a release agent, not a sealing layer for an adhesive. Even if this filling layer is used for the pressure-sensitive adhesive, after applying the alcohol solution of polyvinyl acetate hydrolyzate to the substrate,
It is not efficient because a step of drying the solution is required before applying the pressure-sensitive adhesive, and additional manufacturing equipment and manufacturing steps are required.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and can suppress the permeation of an adhesive into a porous substrate and reduce the amount of excess adhesive used. It is also an object of the present invention to provide a method for producing an adhesive tape having high productivity.

[0008]

The method for producing a pressure-sensitive adhesive tape according to the present invention is a method for producing a pressure-sensitive adhesive tape in which a hot-melt adhesive is applied to one surface of a porous substrate to provide a pressure-sensitive adhesive layer. A liquid not compatible with is applied to a porous base material, and a hot melt adhesive containing a thermoplastic block copolymer rubber as a main component is applied to the liquid application surface.

The porous substrate used in the present invention is a kraft paper, a woven fabric, a non-woven fabric or the like having minute voids between the fibers, and the kraft paper is subjected to a curl pack process or wet strengthening (WS). It may be processed. The material of the woven cloth and the nonwoven cloth is not particularly limited as long as it is usually used as a base material of an adhesive tape.

Low-density polyethylene or the like is usually laminated on the back surface of the base material, that is, on the side opposite to the pressure-sensitive adhesive coated surface, and a release treatment is applied to the laminated surface. In the case of kraft paper, a silicone polymer type or a long chain alkyl group-containing polymer type is used as the release agent, and in the case of a woven or non-woven fabric, a long chain alkyl type is generally used by coating. As a means for applying the release agent, a Meyer bar coater, a gravure roll coater, or a conventionally used roll coater can be adopted.

Examples of the liquid that is incompatible with the pressure-sensitive adhesive used in the present invention include water, alcohols such as glycerin and ethylene glycol, and normal hexane. Also,
An aqueous solution of polyvinyl alcohol, polystyrene sulfonic acid, polyethylene imine, etc. can also be used. The liquid or aqueous solution preferably has a boiling point of 100 ° C. or lower.

When water or these liquids are applied to the base material, at the same time, a part of the water is impregnated into the surface layer of the base material to form a thin film of the liquid near the surface of the base material. When melted hot melt adhesive is applied on top of this, the hot melt adhesive is rapidly cooled by the liquid film and solidifies near the surface, so it does not penetrate between the fibers of the base material and is formed into the thickness as designed. It

When used as an aqueous solution, its concentration is 30
% Or less is preferable. If the concentration is higher than 30%, the adhesive performance may be deteriorated due to the bleed-out of oil or the coating agent due to the interaction between the sealing agent and the adhesive.

In addition to the above-mentioned water or aqueous solution, inorganic substances such as calcium carbonate, talc, hollow particles, coal ash and silica-based powder may be dispersed in water. When an inorganic substance is applied together with water, it is deposited in the interstices of the fibers of the other porous base material, seals the interstices on the top surface of the base material and prevents water penetration, and easily forms a thin water film on the top surface of the base material. Become. For this reason, the applied hot-melt pressure-sensitive adhesive is less likely to soak into the base material, and the pressure-sensitive adhesive layer is likely to be formed in a thickness as designed.

The coating amount of the liquid which is incompatible with the above-mentioned pressure-sensitive adhesive varies depending on the kind of the substrate, the concentration of the liquid, etc., but is preferably in the range of 0.1 to 30 g / m ² . If the coating amount is less than 0.1 g / m ² , a water film cannot be formed on the surface of the substrate, and the effect of the present invention cannot be exhibited. If the coating amount exceeds 30 g / m ² , the filling agent will penetrate more into the base material, and in the case of cloth, the base material strength will decrease and the base material may break when packing heavy objects. However, in the case of kraft paper, there is a problem that the strength is too high and the packing work becomes difficult.

(Function) Since a liquid which is incompatible with the hot melt adhesive is applied to the porous base material, and the hot melt adhesive containing the thermoplastic block copolymer rubber as a main component is applied to the liquid application surface. A thin film of liquid is formed on the surface of the substrate by the liquid, and the hot-melt adhesive applied on the liquid is rapidly solidified by the cooling action of the liquid film and impregnated between the fibers of the substrate. Suppressed. As a result, the hot melt adhesive layer can be formed with the thickness as designed, and the manufacturing efficiency becomes very high. On the other hand, since the liquid applied to the base material is almost evaporated by the heat of the hot melt adhesive in a molten state, it is not necessary to provide a drying step.

[0017]

Embodiments of the present invention will be described below. (Example 1) Low density polyethylene was melt-extruded on one side of kraft paper (basis weight 73 g / m ² ) that had been subjected to WS Clupack processing and laminated with a thickness of 20 μm, and a silicone polymer release agent was solidified on the laminated surface. 0.8 g / min
It was coated and dried so as to have a size of m ² to obtain a base material for an adhesive tape. Water was applied to the surface of the base material opposite to the release agent application surface using a Meyer bar coater in an amount of 5 g / m ² . Immediately thereafter, 160 parts of hot melt adhesive having the composition shown in Table 1 was used.
The adhesive tape was obtained by coating the surface coated with water at 50 g / m ² in a state of being melted at ℃.

(Example 2) An adhesive tape was obtained in the same manner as in Example 1 except that an aqueous glycerin solution (concentration: 40% by weight) was applied at about 10 g / m ² instead of water.

Comparative Example 1 An adhesive tape was obtained in the same manner as in Example 1 except that water was not applied to the base material.

(Comparative Example 2) An adhesive tape was obtained in the same manner as in Comparative Example 1 except that the coating amount of the hot melt adhesive was 60 g / m ² .

(Example 3) 45 warp yarns of 30 count yarn
/ 25 mm, width 33 pcs / 25 mm
In the same manner as in Example 1, the thickness is set to 100 μm.
Polyethylene with a long chain
Alkyl-based mold release agent 0.5g / m in solid content ^TwoSo that
Was applied and dried to obtain an adhesive tape substrate. With this base material
The amount of water applied is about 10 g / m^TwoAnd hot melt viscosity
Coating amount of adhesive is 200g / m^TwoExample 1 except that
Similarly, an adhesive tape was obtained.

Example 4 An adhesive tape was obtained in the same manner as in Example 3 except that an aqueous polyvinyl alcohol solution (concentration: 20% by weight) was applied in an amount of about 10 g / m ² instead of water.

(Example 5) Instead of water, about 10 parts of an aqueous dispersion of calcium carbonate (specific gravity 2.6) (concentration 5% by weight) was used.
An adhesive tape was obtained in the same manner as in Example 3 except that the adhesive tape was applied at g / m ² .

Comparative Example 3 An adhesive tape was obtained in the same manner as in Example 3, except that water was not applied to the base material.

Comparative Example 4 An adhesive tape was obtained in the same manner as in Example 3 except that the coating amount of the hot melt adhesive was 240 g / m ² .

(Example 6) Normal hexane was applied at 5 g / m ² instead of water, and the hot melt adhesive shown in Table 1 was melted at 170 ° C. to 50 g / m ² on this coated surface.
An adhesive tape was obtained in the same manner as in Example 1 except that ² was applied.

(Example 7) Normal hexane was applied at 10 g / m ² instead of water, and 200 g of the hot-melt pressure-sensitive adhesive shown in Table 1 was melted at 170 ° C on the coated surface.
A pressure-sensitive adhesive tape was obtained in the same manner as in Example 3 except that / m ² was applied.

(Example 8) An adhesive tape was obtained in the same manner as in Example 6 except that the coating amount of normal hexane was 8 g / m ² .

Comparative Example 5 An adhesive tape was obtained in the same manner as in Example 6 except that neither water nor normal hexane was applied.

Comparative Example 6 An adhesive tape was obtained in the same manner as in Example 7 except that normal hexane was not applied.

(Comparative Example 7) An adhesive tape was obtained in the same manner as in Comparative Example 5 except that the coating amount of the hot melt adhesive was 60 g / m ² .

(Comparative Example 8) An adhesive tape was obtained in the same manner as in Comparative Example 6 except that the coating amount of the hot melt adhesive was 240 g / m ² .

[0033]

[Table 1]

With respect to the pressure-sensitive adhesive tapes obtained in the above Examples and Comparative Examples, the thickness of the pressure-sensitive adhesive layer, the pressure-sensitive adhesive properties, and the strength of the pressure-sensitive adhesive tape were measured by the following methods. Measurement method (1) Thickness of adhesive layer The thickness of the adhesive layer was determined by subtracting the thickness of the substrate from the thickness of the entire adhesive tape. (2) SP adhesive strength For adhesive tapes based on Kraft paper, JIS
It was measured according to Z 1523. The adhesive tape using a cloth as a base material was measured according to JIS Z 1524. (3) Ball tack Measured according to JIS Z 0237. (4) Holding power The sample is cut into 25mm width, and 25mm on the edge of the steel plate.
It was adhered so as to have an area of × 25 mm, and the pressure roll was pressed back and forth once with a pressure of 2 kg. This was stood in the vertical direction, a load of 1 kg was applied to the sample, and the deviation value after 2 hours was measured. (5) Tensile strength For adhesive tapes based on kraft paper, JIS
Measured according to Z 1523. The adhesive tape using a cloth as a base material was measured according to JIS Z 1524. (6) Tear strength For adhesive tapes based on Kraft paper, JIS
It was measured according to Z 1523. The adhesive tape using a cloth as a base material was measured according to JIS Z 1524. The above results are shown in Table 2 for Examples 1-5 and Comparative Examples 1-4, and in Table 3 for Examples 6-8 and Comparative Examples 5-8.

[0035]

[Table 2]

[0036]

[Table 3]

As can be seen from Table 2, in the case of Examples 1 and 2 using kraft paper as the base material, water was applied before the adhesive was applied. The strength of the material has improved. Comparative Example 3 in which water was not applied to the base fabric
The adhesive strength of each of Examples 3 to 5 was lower than that of Examples 3 to 5, and when a large amount of adhesive was applied as in Comparative Example 4, the adhesive strength of Examples 2 and 4 was obtained. From this, it can be seen that according to the method of the present invention, a predetermined adhesive force can be obtained even if the amount of the adhesive used is reduced.

Further, according to Table 3, the pressure-sensitive adhesive tape produced using normal hexane without undergoing a drying step did not give off an odor in which the residual solvent in the substrate was in the range of 1000 ppm or less.

[0039]

Industrial Applicability Since the method for producing the pressure-sensitive adhesive tape of the present invention is as described above, it is possible to suppress the permeation of the pressure-sensitive adhesive into the porous substrate and reduce the amount of excess pressure-sensitive adhesive used. The hot melt pressure-sensitive adhesive layer can be formed with the same thickness and can be manufactured very efficiently. Further, since the liquid applied to the base material is almost evaporated by the heat of the hot-melt pressure-sensitive adhesive in a molten state, there is no need to provide a drying step. Furthermore, an organic solvent is used as a liquid, and a pressure-sensitive adhesive tape having no solvent odor can be obtained without a drying step.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location C09J 7/02 JJY C09J 7/02 JJY 7/04 JHW 7/04 JHW

Claims (1)

[Claims] 1. A method for producing a pressure-sensitive adhesive tape in which a hot-melt pressure-sensitive adhesive is applied to one surface of a porous substrate to form a pressure-sensitive adhesive layer, wherein a liquid that is incompatible with the hot-melt pressure-sensitive adhesive is applied to the porous substrate. A method for producing an adhesive tape, characterized in that a hot melt adhesive containing a thermoplastic block copolymer rubber as a main component is applied to the liquid application surface.