JP2000017237A - Preparation of air permeable adhesive tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive sheet with a good color developing ability and a sufficient flexibility, therefore an excellent adhesiveness to a curved surface, though using an olefinic resin substrate sheet which can reduce incineration load. SOLUTION: This adhesive sheet is prepd. by laminating an adhesive layer on one of the surfaces of an olefinic resin laminate sheet comprising an intermediate layer comprising an olefinic resin sheet consisting of (1) 20-100 wt.% of an amorphous olefinic resin prepd. by copolymerizing with 50 wt.% or more of butene-1 or a mixture of butene-1 and propylene, and (2) 0-80 wt.% of an olefinic resin other than the olefinic resin (1), the laminate sheet also comprising the two outer layers of propylene type resin sheets.

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 gas-permeable pressure-sensitive adhesive tape used for, for example, a plaster, and more particularly to a method in which a pressure-sensitive adhesive layer is partially impregnated into a gas-permeable fibrous base material. The present invention relates to a method for producing a gas-permeable pressure-sensitive adhesive tape having gas permeability.

[0002]

2. Description of the Related Art As a non-breathable adhesive tape such as an adhesive bandage or an adhesive bandage, if it is used, there is a problem that use of the adhesive tape causes rash on the skin and delays recovery of the wound. Therefore, various attempts have been made to provide air permeability in the above-mentioned surgical adhesive tape.

For example, (1) a method of laminating a pressure-sensitive adhesive layer on a base material sheet in a stripe pattern, and (2) a method of changing the rotation speed ratio between a coating roll and a metalling roll to roughen a coated surface of a high-viscosity pressure-sensitive adhesive. A method of imparting air permeability by
(3) A method of blending a foaming agent, and (4) a method of spraying water with a jet nozzle immediately after applying an adhesive are known. However, all of the above methods have problems in that the workability at the time of applying the pressure-sensitive adhesive is poor, the air permeability is non-uniform, and the air permeability is lost over time.

Japanese Patent Publication No. 63-45545 proposes a method in which a pressure-sensitive adhesive solution is directly applied to a tape base having air permeability and then dried. However, this method has a problem that the pressure-sensitive adhesive easily leaks out to the back surface of the tape substrate.

Therefore, in the manufacturing process, the speed ratio of the coating roll, the distance from the coating unit to the drying furnace, the winding speed,
Considering various factors such as the composition and basis weight of the tape substrate, viscosity of the adhesive, thixotropic or fluidity, or impregnation, conditions that can prevent the exudation of the adhesive to the back of the tape substrate are determined. Had to choose. However, there is a problem that it is very difficult to set the optimal conditions because various factors as described above influence, and even if the optimum conditions can be set, the process management is very complicated.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, maintains a stable and uniform air permeability over time, and provides a breathable pressure-sensitive adhesive tape which does not require complicated process control in production. It is intended to provide a manufacturing method.

[0007]

According to a first aspect of the present invention, there is provided a method for producing a gas-permeable pressure-sensitive adhesive tape, wherein one part of an acrylic pressure-sensitive adhesive and an organic peroxide are coated on one surface of a gas-permeable fibrous base material. After laminating an adhesive layer having a gel fraction of less than 40% consisting of .01 to 10 parts by weight by transfer, the adhesive layer is heated to soften the adhesive layer and impregnate it into a gas-permeable fibrous base material. The method is characterized in that the agent layer is crosslinked so that the gel fraction becomes 40 to 90% after or while aerating the agent layer.

According to a second aspect of the present invention, there is provided a method for producing a gas-permeable pressure-sensitive adhesive tape, wherein 100 parts by weight of an acrylic pressure-sensitive adhesive and benzoyl peroxide or dichlorobenzoyl peroxide are coated on one surface of a gas-permeable fibrous base material. ~
After laminating an adhesive layer composed of 5.0 parts by weight and having a gel fraction of less than 30% by transfer, the adhesive layer is heated at a temperature of 60 to 100 ° C. to soften the adhesive layer so that the air-permeable fibrous base is formed. After the pressure-sensitive adhesive layer is aerated by impregnating the material, or while the aerated, the gel fraction is 40 to 70%.
It is characterized by cross-linking so that

According to a third aspect of the present invention, there is provided a method of manufacturing a breathable pressure-sensitive adhesive tape according to the first or second aspect, wherein radiation is applied as a crosslinking method. It is.

According to a fourth aspect of the present invention, there is provided a method for producing a gas-permeable pressure-sensitive adhesive tape, wherein one surface of an air-permeable fibrous base material is provided with 100 parts by weight of an acrylic pressure-sensitive adhesive and 0.01 to 1.0% of an isocyanate-based crosslinking agent. After laminating an adhesive layer composed of parts by weight and having a gel fraction of less than 30% by transfer, the adhesive layer is softened by heating at a temperature of 70 to 100 ° C. to impregnate the air-permeable fibrous base material. After the pressure-sensitive adhesive layer is aerated, or while the aerated, the gel fraction is 4
It is characterized in that it is crosslinked so as to be 0 to 70%.

[0011] The method for producing a breathable pressure-sensitive adhesive tape according to the invention according to claim 5 is the production method according to claims 1 to 4,
In particular, the transferred pressure-sensitive adhesive layer has releasability on at least one surface, and the pressure-sensitive adhesive solution is applied to the concave portion forming surface of the release film in which a large number of concave portions are uniformly formed and dried. The gel fraction is less than 30%.

(1) Fibrous base material having air permeability Examples of the fibrous base material having air permeability used in the present invention include cotton cloth, rayon fiber, polyester fiber, and the like.
Polyurethane fiber, nylon fiber, acrylic fiber, pulp, hemp, vinylon fiber, and the like, or a nonwoven fabric made of a mixed fiber of two or more of these, are used. Is preferred.

As the fibrous base material, it is preferable to use a fibrous base material having an air permeability of 10 seconds / 300 ml or less specified in JIS P 8117 in order to facilitate the impregnation with an adhesive.

(2) Adhesive The adhesive used in the first to third aspects of the present invention will be described in detail below. The pressure-sensitive adhesive used in the first aspect of the present invention comprises 100 parts by weight of an acrylic pressure-sensitive adhesive and 0.01 to 10 parts by weight of an organic peroxide. Examples of the acrylic pressure-sensitive adhesive include all those mainly containing an acrylic copolymer obtained by copolymerizing a mixed monomer composed of an alkyl (meth) acrylate and a polar group-containing vinyl monomer. The method is not particularly limited.

Examples of the alkyl (meth) acrylate include ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, hexyl (meth) acrylate, Examples include ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, and lauryl (meth) acrylate.

The above-mentioned polar group-containing vinyl monomer is copolymerized so as to be a cross-linking base point in the acrylic copolymer. For example, (meth) acrylic acid, itaconic acid,
Carboxyalkyl (meth) such as crotonic acid, (anhydride) maleic acid, fumaric acid, carboxyethyl acrylate
Carboxyl group-containing vinyl monomers such as acrylates;
Examples include hydroxyl-containing vinyl monomers such as 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and caprolactone-modified (meth) acrylate.

The weight average molecular weight of the acrylic copolymer in terms of polystyrene measured by gel permeation chromatography (GPC) is preferably 400,000 to 800,000.

Other substances may be added to the acrylic pressure-sensitive adhesive. Examples of such additives include tackifying resins, extenders, and fillers.

The above-mentioned organic peroxide has been used in view of the fact that the rate of the crosslinking reaction is slower than that of the conventional crosslinking agent. It is possible to promote.
As the organic peroxide, for example, benzoyl peroxide, dichlorobenzoyl peroxide, t-butyl peroxy neodecaate, t-butyl peroxypivalate, t-butyl peroxybenzoate, 3,5,5
5-trimethylhexyl peroxide, 1,1-bis (t-butylperoxyl) 3,3,5-trimethylcyclohexane and the like.

If the amount of the organic peroxide is too small, the desired degree of crosslinking cannot be obtained, and if it is too large, the air permeability may be deteriorated, and the gel fraction after curing may exceed 90%, and the adhesive strength may be reduced. Since it may decrease, it is 0.01 to 10 parts by weight based on 100 parts by weight of the acrylic pressure-sensitive adhesive.

According to the second aspect of the present invention, in particular, since the organic peroxide reacts at a relatively high temperature, the crosslinking reaction hardly proceeds at 60 to 100 ° C. at which the pressure-sensitive adhesive layer can be softened. Oxide and dichlorobenzoyl peroxide are suitably used, and the amount of addition is preferably 0.01 to 5.0 parts by weight for the same reason as described above.

In order to laminate the pressure-sensitive adhesive layer comprising the acrylic pressure-sensitive adhesive and the organic peroxide on a fibrous base material having air permeability, the pressure-sensitive adhesive is usually applied to release paper and dried to form the pressure-sensitive adhesive layer. A method of forming and then stacking by transfer is common.

The thickness of the pressure-sensitive adhesive layer is 20 to 100 μm after drying.
It is preferable to set m. If it is less than 20 μm, the adhesive strength is insufficient, and if it exceeds 100 μm, the air permeability is 10 seconds /
It is not preferable because it becomes larger than 300 ml.

The pressure-sensitive adhesive layer of the present invention is laminated on a gas-permeable fibrous base material and then softened by heating, and falls into a relatively large void near the surface of the gas-permeable fibrous base material. , Is ventilated. For this reason, the pressure-sensitive adhesive layer before ventilation is insufficient in softening by heating if the gel fraction is high, and it is difficult to obtain air permeability, so the pressure-sensitive adhesive layer must be less than 40%. In the second aspect of the invention, the content is particularly preferably less than 30% for the same reason as described above.

If the heating temperature at this time is low, the softening is insufficient and the gas is hardly ventilated, and if the heating temperature is high, the pressure-sensitive adhesive and the fibrous base material having air permeability may be deteriorated and yellowed.
The range of 0-100 degreeC is preferable.

The gas-permeable pressure-sensitive adhesive tape has a gel fraction of 4 after gas-permeable or while gas-permeable.
Crosslinked so as to be 0 to 90%. If the gel fraction at this time is less than 40%, the pressure-sensitive adhesive tends to flow, and the ventilated pressure-sensitive adhesive layer may re-adhere, resulting in reduced air permeability over time. Power may decrease.

Examples of the above-mentioned crosslinking method include curing by heating, irradiation with radiation, and the like. The above-mentioned heat curing is to cure in a rolled or single-leaf state, for example, in a heat curing room at 40 to 80 ° C. for 24 hours or more.
Cured for more than an hour. In the case of irradiation with radiation, a method of irradiating ultraviolet light to the ventilated adhesive tape using an ultraviolet lamp can be used. This method is suitable because it can be performed in-line and does not require curing.

Hereinafter, the invention of claim 4 will be described in detail. The pressure-sensitive adhesive used in the invention according to claim 4 comprises 100 parts by weight of an acrylic pressure-sensitive adhesive and 0.01 to 1.0 part by weight of an isocyanate-based cross-linking agent. Examples of the acrylic pressure-sensitive adhesive include all those described above, but it is necessary that active hydrogen capable of reacting with the isocyanate-based cross-linking agent is introduced into the pressure-sensitive adhesive base polymer.

If the amount of the isocyanate-based crosslinking agent is too small, a desired degree of crosslinking cannot be obtained, and if it is too large, the air permeability may be deteriorated, and the gel fraction after curing may exceed 90%, and the adhesive strength may be reduced. Since it may decrease, it is 0.01 to 1.0 part by weight based on 100 parts by weight of the acrylic pressure-sensitive adhesive.

In order to laminate the pressure-sensitive adhesive layer comprising the acrylic pressure-sensitive adhesive and the isocyanate-based cross-linking agent on a fibrous base material having air permeability, the pressure-sensitive adhesive is usually applied to release paper and dried to form the pressure-sensitive adhesive layer. A method of forming and then stacking by transfer is common.

The thickness of the pressure-sensitive adhesive layer is 20 to 100 μm after drying.
It is preferable to set m. If it is less than 20 μm, the adhesive strength is insufficient, and if it exceeds 100 μm, the air permeability is 10 seconds /
It is not preferable because it becomes larger than 300 ml.

The pressure-sensitive adhesive layer of the present invention is laminated on an air-permeable fibrous base material, and then softened by heating. Depressed and ventilated. For this reason, the pressure-sensitive adhesive layer before aeration is insufficient in softening by heating if the gel fraction is high, and it is difficult to obtain air permeability, so that the pressure-sensitive adhesive layer must be less than 30%.

If the heating temperature at this time is low, the softening is insufficient and the air is not easily ventilated, and if the heating temperature is high, the adhesive may deteriorate or the fibrous base material having air permeability may deteriorate yellowing.
Limited to 0-100 ° C.

The gas-permeable pressure-sensitive adhesive tape has a gel fraction of 4 after gas-permeable or while gas-permeable.
Crosslinked so as to be 0 to 70%. If the gel fraction at this time is less than 40%, the pressure-sensitive adhesive tends to flow, and the gas-permeable pressure-sensitive adhesive layer may re-adhere, resulting in reduced air permeability over time. Power may decrease.

As the crosslinking method, the above-mentioned claims 1-3
Similarly to the invention, heating curing, radiation irradiation and the like can be mentioned.

When the pressure-sensitive adhesive layer is obtained, a pressure-sensitive adhesive solution is applied to the surface of the release film of the release film having at least one surface having releasability and having a large number of uniformly formed concave portions. By laminating a pressure-sensitive adhesive having a dried gel fraction of less than 30% on one surface of the fibrous base material having air permeability, and then heating and ventilating in the same manner as described above, the pressure-sensitive adhesive becomes more effective. It is possible to make it ventilated.

Further, the pressure-sensitive adhesive tape obtained by the production method according to the fifth aspect of the present invention has improved air permeability. The release film in which the plurality of concave portions are formed will be described in detail below. As the resin constituting the release film, for example, low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene,
Ethylene-α-olefin copolymer, propylene-α-
Olefin copolymer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, ethylene-based copolymer such as ethylene-methyl methacrylate copolymer,
Examples include polypropylene and polystyrene.

The release film may be one obtained by subjecting the surface of the above-mentioned resin sheet to a release treatment. Specifically, a silicone release agent, a fluorine release agent, and a long-chain alkyl release agent may be used. And the like, to which an agent or the like is applied. The surface wetting tension of the release film is preferably 31 dyne / cm or less.

The concave portion formed on the release film has a downward direction of less than 90 ° from the surface toward the bottom of the concave portion,
Preferably formed in a direction of less than 70 °,
Various shapes such as a pyramid, a diamond, a dot, a stripe, and a half moon can be given.
It may be used in combination of more than one kind. Further, it is preferable that a large number of the concave portions are formed on the surface of the release film, and the ratio of the concave portion to one surface of the release film is preferably less than 50%.

The depth of the concave portion is preferably from 10 to 200 μm because the actual transfer amount is small when the depth is small, and it is difficult to obtain a large adhesive force, and when the depth is deep, the transfer is difficult regardless of the material of the nip roll.

[0041]

Embodiments of the present invention will be described below. (Examples 1-4, Comparative Examples 1-2) According to the composition of Table 1,
Acrylic adhesive (manufactured by Soken Chemical Co., Ltd., trade name "SK Dyne 1720") and benzoyl peroxide (hereinafter, referred to as
BPO) and dried on release paper to a thickness of 50
μm to form a pressure-sensitive adhesive layer, and then apply the pressure-sensitive adhesive layer to the air-permeable fibrous base material made of polyurethane fiber (Kanebo Co., trade name “Espansione”, (Weight: 75 g / m ² , air permeability: 0 sec), cut into sheets in a state where release paper is also laminated, left in a constant temperature bath at 85 ° C for 48 hours to allow ventilation, and then to 85 ° C The adhesive tape was obtained by heating and curing for 48 hours in a constant temperature bath.

(Examples 5 and 6) According to the composition shown in Table 1, an acrylic pressure-sensitive adhesive (trade name "SK Dyne 1" manufactured by Soken Chemical Co., Ltd.)
720 ") and BPO, and coated and dried on a release paper so that the thickness after drying becomes 50 μm to form an adhesive layer. Then, the adhesive layer is made of a breathable polyurethane fiber having air permeability. Fibrous base material (manufactured by Kanebo Co., Ltd., trade name "Espancione", basis weight 75 g / m ² , air permeability 0)
Second), the release paper is also laminated, cut into sheets, left in a constant temperature bath at 85 ° C. for 48 hours to ventilate, and the release paper is peeled off, and has a strength of 25 mW / cm ² . Irradiation with ultraviolet light for 3 minutes (0.05 hours) resulted in cross-linking to obtain an adhesive tape.

(Examples 7 to 12) According to the composition shown in Table 2,
A pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that an acrylic pressure-sensitive adhesive (manufactured by Soken Chemical Co., Ltd., trade name “SK Dyne 1720”) and BPO or dichlorobenzoyl peroxide (hereinafter referred to as DC-BPO) were mixed. Was.

(Examples 13 to 15, Comparative Examples 3 to 5) Table 3
An acrylic pressure-sensitive adhesive (manufactured by Soken Chemical Co., Ltd., trade name "SK Dyne 1720") and an isocyanate-based cross-linking agent are mixed according to the composition described above, and applied to a release paper so as to have a thickness of 50 μm after drying, followed by drying. After forming a layer, the pressure-sensitive adhesive layer is formed into a breathable fibrous base material made of polyurethane fiber having breathability (trade name “Espansione” manufactured by Kanebo Co., Ltd., basis weight 75 g / m ² , air permeability 0) (Sec), release paper is laminated and cut into sheets, left in a constant temperature bath at each temperature for 48 hours to ventilate, and left to cure in a constant temperature bath at 85 ° C for 48 hours. Thus, an adhesive tape was obtained.

(Examples 16 to 21) Medium density polyethylene (manufactured by Mitsui Petrochemical Co., Ltd., trade name "Neozex 3510")
F ", MFR (190 ° C) = 1.6 g / 10 min) to obtain a 90 µm base film. Next, on one side of the base film, 6
The mold is released by forming an embossment in a direction perpendicular to the film unwinding direction so that a portion having the inclination is 0 °, the depth is 60 μm, and the distance between the center points of the concave portions is 1 mm, and 500 μm of the concave portion occupies 500 μm. A film was obtained.

Next, according to the composition shown in Table 4, the acrylic
Adhesive (manufactured by Soken Chemical Co., Ltd., product name "SK Dyne 172"
0 ") and BPO or dichlorobenzoyl peroxy
A mixture of sides (hereinafter referred to as DC-BPO)
To the release film at 30 g / m ^TwoApply so that
Dry to form a pressure-sensitive adhesive layer, then breathe the pressure-sensitive adhesive layer
Breathable fiber made of polyurethane fiber
Base material (manufactured by Kanebo, product name "Espancione", basis weight 7)
5g / m2, air permeability 0 sec)
In a state of lamination, and cut into sheets at a constant temperature bath at each temperature.
Leave it for 8 hours to ventilate, and then put it in a thermostat at 85 ° C for 48 hours.
The adhesive tape was obtained by heating and curing for a period of time.

(Evaluation Items) The results measured for the following items are shown in Tables 1 to 4. (1) Gel fraction A predetermined amount of the pressure-sensitive adhesive layer was sampled, left for 24 hours in a state of being immersed in approximately 100 times the amount of tetrahydrofuran, and then filtered through a 300-mesh stainless steel wire mesh to crosslink the portion remaining on the wire mesh. The gel fraction was determined by calculation as a polymer. The gel fraction was measured both immediately after lamination on the air-permeable fibrous base material and after complete cross-linking by heat curing or ultraviolet irradiation.

(2) Air permeability The pressure-sensitive adhesive tapes obtained in Examples and Comparative Examples
In accordance with ISP 8117, the air permeability was measured both immediately after the production and after leaving for one month.

(3) Adhesive force to stainless steel plate The adhesive tapes obtained in Examples and Comparative Examples
Stainless steel plate (SUS # in accordance with IS Z 0237)
The 180 ° peel adhesion to 304) was measured.

(4) Holding force against stainless steel plate The pressure-sensitive adhesive tapes obtained in Examples and Comparative Examples
Stainless steel plate (SUS # in accordance with IS Z 0237)
304) was measured.

[0051]

[Table 1]

[0052]

[Table 2]

[0053]

[Table 3]

[0054]

[Table 4]

[0055]

According to the method for producing a breathable pressure-sensitive adhesive tape according to the first aspect of the present invention, the progress of crosslinking is slowed down by the organic peroxide compounded in the pressure-sensitive adhesive layer, so that the pot life of the pressure-sensitive adhesive is increased. It can be manufactured without the need for complicated process control in the manufacture, and is further cross-linked so that the gel fraction of the pressure-sensitive adhesive becomes 40 to 90% after imparting air permeability, so that it is stable and uniform over time. A breathable pressure-sensitive adhesive tape having breathability and adhesive strength is obtained.

In the method for producing a breathable pressure-sensitive adhesive tape according to the second aspect of the present invention, benzoyl peroxide or dichlorobenzoyl peroxide is particularly used as the organic peroxide, so that the ventilation can be more effectively achieved. .

In the method for producing a breathable pressure-sensitive adhesive tape according to the third aspect of the present invention, a crosslinking step can be provided in-line during the production by crosslinking with ultraviolet rays instead of heat, so that a step such as curing is not required. it can.

In the method for producing a breathable pressure-sensitive adhesive tape according to the fourth aspect of the present invention, an isocyanate-based cross-linking agent is used in place of the organic peroxide, and the progress of cross-linking is slowed. It can be manufactured without the need for complicated process control in the manufacturing process, and is further cross-linked so that the gel fraction of the pressure-sensitive adhesive becomes 40 to 70% by cross-linking after imparting air permeability. A breathable pressure-sensitive adhesive tape having uniform breathability and adhesive strength is obtained.

In the method for producing a gas-permeable pressure-sensitive adhesive tape according to the fifth aspect of the present invention, the pressure-sensitive adhesive layer to be transferred is previously formed in a gas-permeable dot-like or stripe-like shape, so that the air-permeable pressure-sensitive adhesive tape is more effectively ventilated. it can.

Claims (5)

[Claims] 1. One side of an air-permeable fibrous base material is provided with 100 parts by weight of an acrylic pressure-sensitive adhesive and 0.01% of an organic peroxide.
After laminating a pressure-sensitive adhesive layer having a gel fraction of less than 40% by transfer and laminating by heating, the pressure-sensitive adhesive layer is softened by heating and impregnated into the fibrous base material to make the pressure-sensitive adhesive layer aerated. A method for producing a gas-permeable pressure-sensitive adhesive tape, which comprises cross-linking so as to have a gel fraction of 40 to 90% after or while ventilating. 2. One side of an air-permeable fibrous base material is provided with 100 parts by weight of an acrylic pressure-sensitive adhesive and 0.01 parts of benzoyl peroxide or dichlorobenzoyl peroxide.
After laminating a pressure-sensitive adhesive layer having a gel fraction of less than 30% by transfer, the softened pressure-sensitive adhesive layer is heated at a temperature of 60 to 100 ° C. to impregnate the fibrous base material. The method for producing a gas-permeable pressure-sensitive adhesive tape according to claim 1, wherein the pressure-sensitive adhesive layer is cross-linked so as to have a gel fraction of 40 to 70% after or while gas-permeable. 3. The method for producing a breathable pressure-sensitive adhesive tape according to claim 1, wherein radiation is applied as a crosslinking method. 4. A pressure-sensitive adhesive layer comprising 100 parts by weight of an acrylic pressure-sensitive adhesive and 0.01 to 1.0 part by weight of an isocyanate-based crosslinking agent and having a gel fraction of less than 30%, on one surface of a fibrous base material having air permeability. Is laminated by transfer, and then heated at a temperature of 70 to 100 ° C. to soften the pressure-sensitive adhesive layer and impregnate the air-permeable fibrous base material into the pressure-sensitive adhesive layer. A method for producing a gas-permeable pressure-sensitive adhesive tape, wherein crosslinking is carried out so that the gel fraction becomes 40 to 70% while forming. 5. The method according to claim 5, wherein the transferred pressure-sensitive adhesive layer has a releasability on at least one surface thereof, and a pressure-sensitive adhesive solution is applied to the surface of the release film on which the plurality of concave portions are uniformly formed. 5. The method for producing a breathable pressure-sensitive adhesive tape according to claim 1, wherein the dried gel fraction is less than 30%.