JPH04175390A - Preparation of air-permeable pressure-sensitive adhesive tape or sheet - Google Patents

Abstract

PURPOSE:To obtain an air-permeable pressure-sensitive adhesive tape or sheet with excellent air permeability an uniformity on air permeability by specifying the range of the max. particle diameter and that of the average particle diameter of water particle in air before adhering to the surface of a layer of a soln. of a pressure- sensitive adhesive. CONSTITUTION:In a method for manufacturing an air-permeable pressure-sensitive adhesive tape or sheet wherein the surface of a release sheet 10 is coated with an org. solvent soln. of a pressure-sensitive adhesive to form a layer 11 of a pressure-- sensitive adhesive soln. and while the layer 11 of the pressure--sensitive adhesive soln. is under an undried condition, water is sprayed as a water drop 12 on the surface of this layer 11 and dried, and then the obtd. dried pressure-sensitive adhesive layer 11B is laminated with an air-permeable base material, the abovedescribed spraying is performed in such a way that the max. particle diameter and average particle diameter of the water drop in air is, respectively, 300mum or smaller and 1-150mum or smaller. It is possible thereby to form uniformly an air-permeable hole 14 with surely excellent air permeability on the dried pressure-sensitive adhesive layer 11B and to manufacture and air-permeable pressure-sensitive adhesive tape or sheet with excellent and uniform air permeability.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing a breathable adhesive tape or sheet used for medical and other uses.

(Prior Art) Conventionally, medical adhesive products such as bandages are used by being applied directly to the human body, but if left in that state for a long time,
This blocks moisture from evaporating from the skin's surface, causing itching and rashes.

In order to prevent this, it is effective to make the adhesive product breathable. Therefore, many attempts have been made to make adhesive products breathable.

As a new example, for example, an organic solvent solution of an adhesive is applied to the surface of a releasable sheet to form an adhesive solution layer, and then, while the adhesive solution layer is in an undried state, a predetermined amount of water is applied. There is a known method of spraying water droplets on the surface of the pressure-sensitive adhesive solution layer, drying the droplets to form a dry pressure-sensitive adhesive layer having micropores, and laminating this onto a breathable base material. There is. The principle of forming vent holes in the dry adhesive layer by this method is as shown in FIG. That is, the adhesive solution layer (1
1) is in an undried state, the adhesive solution layer (11)
When water is sprinkled on the surface of the adhesive solution layer (12), the attached water droplets (12) form an adhesive solution layer (1
1), thereby forming minute depressions (13) on the surface of the adhesive solution layer (11). Next, when it is dried in a drying device, both the water and the solvent evaporate, and as shown in FIG. flows and the recess (13) becomes slightly smaller. At this time, the thickness of the adhesive solution layer (11) also becomes thin. As water evaporates through subsequent drying, the remaining water droplets (12) become smaller than the concavities (13), as shown in Figure 1 (C), but the solvent also evaporates and the viscosity of the adhesive decreases. As the pressure increases, the adhesive no longer flows, and an intermediate adhesive layer (11^) is obtained.

The thickness of the adhesive layer (IIA) in the intermediate state is even thinner than that shown in FIG. 1(b). Furthermore, as the water and solvent evaporate, the adhesive layer (IIA) contracts and the recess (13) widens, as shown in Figures 1(d) and (e), and the water completely evaporates. do. After that, the solvent continues to evaporate and the adhesive layer (IIA) continues to shrink, and as shown in Figure 1(f), the bottom of the recess (13) is torn off and a vent hole (14) is formed. At the same time, the viscosity of the adhesive is increased to the desired viscosity. Thus, the vent (14)
A dry adhesive layer (IIB) is formed.

This method is attracting attention as a relatively simple method.

(Problems to be Solved by the Invention) However, in the above method, there is a problem that the air permeability of the manufactured air permeable adhesive tape or sheet varies, and some tapes or sheets do not have the desired air permeability.

Therefore, in order to ascertain the cause of the above-mentioned problem, the present inventors conducted various experiments and research, and found that in the spraying step of the above-mentioned method, the particle size of water droplets in the air before adhering to the surface of the adhesive solution layer is It has been found that the above-mentioned problem occurs when the particle size of the water droplets is outside a predetermined range, and has a large effect on the ventilation performance of the manufactured product.

An object of the present invention is to solve the above-mentioned problems and provide a method for producing a breathable adhesive tape or sheet that has excellent ventilation performance and is consistent in ventilation performance.

(Means for Solving the Problems) A method for producing a breathable adhesive tape or sheet according to the present invention includes applying an organic solvent solution of an adhesive to the surface of a releasable sheet to form an adhesive solution layer. While the layer is in an undried state, water is sprinkled on the surface of the pressure-sensitive adhesive solution layer in the form of droplets and then dried, and then the resulting dry pressure-sensitive adhesive layer is laminated on a breathable substrate. In the method for producing a breathable adhesive tape or sheet, the water is sprayed so that the maximum particle size of the water droplets in the air is 300 μm.
The following is characterized in that it is carried out so that the average particle diameter is 1 to 150 μm.

In the above, the reason why the particle size of water droplets in the air in the spraying step is limited as described above is as follows. In other words, in order for the dried adhesive layer to have good air permeability, the diameter of the recess formed by the sinking of water droplets attached to the surface of the adhesive solution layer must be within the range of 100 to 400 μm. There must be. Because the diameter of the recess is 100
If it is less than μm, the diameter of the vents formed by subsequent drying becomes small and the ventilation performance of each vent hole is insufficient.
If the diameter of the recess exceeds 400 μm, the hole may not be formed, or the entire recess may not become a hole, but only a part of it may become a hole, and the diameter of the ventilation hole may become smaller, resulting in poor ventilation performance. This is because it will not be sufficient. When the maximum particle size of the water droplets exceeds 300 μm and the average particle size exceeds 150 μm, the diameter of the recess formed by these water droplets depositing on the surface of the adhesive solution layer and sinking is 400 μm.
becomes larger than Therefore, the maximum particle size of the water droplets in the air in the water spraying step should be 300 μm or less, and the average particle size should be within the range of 1 to 150 μm.

Further, it is preferable that the maximum particle diameter of the water droplets in the air in the water spraying step is 50 μm or less, and the average particle diameter is within the range of 5 to 25 μm. Note that even if the average particle diameter of the water droplets is 1 to several μm, the water droplets adhere to the surface of the adhesive solution layer have a required size due to the collection of these water droplets. However, the efficiency will be slightly lower.

In addition, in the above, the amount of water sprayed is 100 to 250 g.
/rrr is preferable. This is because if the amount of water sprayed is less than 100g/rrr, it will not be possible to obtain enough water droplets to form the required number of vents.
This is because if it exceeds 0 g/rrr, the water droplets will become too large and the diameter of the recesses formed in the adhesive solution layer will become too large, which may cause the above-mentioned problems.

As the release sheet, any material can be used as long as it has a release function for the adhesive, but it is typically preferable to use a so-called release paper treated with silicone. Examples of other releasable sheets include steel belts, rotating drums, and the like.

As the adhesive, a rubber adhesive, a synthetic resin adhesive, or the like is used. Examples of rubber-based adhesives include natural rubber or synthetic rubber, tackifying resins such as rosin-based, terpene-based, petroleum-based, etc., and softeners such as various oils dissolved in a solvent such as n-hexane. Suitably used. Also,
As a synthetic resin adhesive, for example, the main monomer is acrylic acid ester such as butyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, etc., and acrylic acid, acrylamide, N-vinyl-2-pyrrolidone, etc. An acrylic pressure-sensitive adhesive obtained by copolymerizing polar monomers such as or other monomers such as acrylic acid ester, methacrylic acid ester, styrene, and vinyl acetate is preferably used. Furthermore, other adhesives such as polyvinyl ether adhesives and polyisobutyl adhesives can also be used.

The above-mentioned organic solvent solution of the adhesive is one in which these adhesive components are dissolved in an organic solvent such as ethyl acetate, toluene, cyclohexane, n-hexane, a mixed solution of 05 to C7 alkanes, etc. These tapes have already been used in known cellophane tapes, craft tapes, and the like. The viscosity of the organic solvent solution is 500-6
000 cps is preferred.

Various known methods, such as a roll coater method, a knife coater method, and an extrusion lip method, can be used to apply the organic solvent solution of the adhesive onto the releasable sheet. The thickness of the applied adhesive solution layer is preferably within the range of 100 to 200 μm.

Examples of the breathable base material include woven fabrics, nonwoven fabrics, paper, cloth, open-cell foam sheets, and non-breathable base materials such as synthetic resin sheets with many fine holes formed therein.

(Function) In the present invention, water is sprayed so that the maximum particle size of water droplets in the air is 300 μm or less and the average particle size is 1 to 150 μm, so that these water droplets do not reach the surface of the adhesive solution layer. The diameter of the recess formed by adhesion and sinking is 10
It falls within the range of 0 to 400 μm. Therefore, by subsequent drying, vent holes with excellent ventilation performance can be formed.

(Examples) Next, examples of the present invention and some comparative examples to be compared with the examples of the present invention will be listed, and the results of evaluation tests for each of the manufactured breathable adhesive tapes will be shown.

Example 1 Toluene solution of acrylic adhesive (solid content 40% by weight,
After forming an adhesive solution layer by coating a 140 μm thick adhesive solution (with a viscosity of 5,000 cps) on release paper, while the adhesive solution layer was still in an undried state, 150 g/rrr of water was sprayed onto the surface using a spray gun in the air. The water droplets were sprayed so that the maximum particle size of the water droplets was 508 ml and the average particle size was 25 μm.

Then, the adhesive solution layer was dried by blowing hot air at a temperature of 120° C. and a wind speed of 3 m/sec for 3 minutes to obtain a dry adhesive layer. The dry adhesive layer thus obtained was laminated on a breathable base material (Tetron nonwoven fabric; manufactured by DuPont) to produce a breathable pressure-sensitive adhesive tape.

Example 2 A breathable adhesive tape was produced in the same manner as in Example 1, except that water was sprayed so that the maximum particle size of water droplets in the air was 30 μm and the average particle size was 15 μm.

Comparative Example 1 Spraying water, the maximum particle size of water droplets in the air is 4008 m1
A breathable adhesive tape was produced in the same manner as in Example 1 except that the average particle diameter was 200 μm.

Comparative Example 2 Spraying water with a maximum particle size of water droplets in the air of 350 μm1
A breathable adhesive tape was produced in the same manner as in Example 1 except that the average particle diameter was 120 μm.

(Evaluation Test) The air permeability of the air permeable adhesive tapes manufactured in Examples 1 and 2 and Comparative Examples 1 and 2 was tested. The air permeability test was conducted by measuring the densometer air permeability (the time it takes for 300 cc of air to pass through a 6.45 cm hole) in accordance with jIsP8117. These results,
Table 1 shows the conditions for spraying water droplets.

(Effects of the Invention) According to the method of the present invention, as described above, ventilation holes having excellent ventilation performance can be reliably and uniformly formed in the dried adhesive layer. Therefore, it is possible to produce a breathable adhesive tape or sheet that has excellent ventilation performance and has consistent ventilation performance.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of forming a dry adhesive layer having fine pores on a releasable sheet in order of process. (10)...Peelable sheet, (11)...Adhesive solution layer, (IIB)...Dry state adhesive layer, (12)
...Water drops. Patent applicant: Sekisui Chemical Co., Ltd. [Figure 1]

Claims (1)

[Claims] An organic solvent solution of an adhesive is applied to the surface of a releasable sheet to form an adhesive solution layer, and while the adhesive solution layer is in an undried state, water is applied to the surface of the adhesive solution layer in the form of water droplets. In the method of manufacturing a breathable adhesive tape or sheet by spraying the water with water, drying it, and then laminating the obtained dry adhesive layer on a breathable base material, the water spraying is carried out in the air. The maximum particle size of water droplets is 300 μm or less,
A method for producing a breathable adhesive tape or sheet, characterized in that the method is carried out so that the average particle diameter is 1 to 150 μm.