JPH0791411B2 - Method for producing breathable polymer film and method for producing breathable adhesive tape or sheet - Google Patents

Description

The present invention relates to a breathable polymer film used as, for example, a sanitary film, and a method for producing a breathable pressure-sensitive adhesive tape or sheet used as a therapeutic tape or the like.

[Conventional technology]

Depending on the application, a polymer film or tape having air permeability is required. For example, a breathable polymer film has been conventionally used as a food packaging or sanitary film. This type of breathable polymer film is manufactured by a dry method or a wet method. As the former, for example, as described in JP-A-62-141041, it is possible to impart air permeability by mixing an inorganic or organic filler into a polyolefin resin, or as described in JP-A-62-286232. After the film is embossed, it is stretched to give air permeability. As the latter, for example, as described in JP-A-59-68342, a dispersion obtained by adding a thickening agent to a vinyl chloride resin obtained by a suspension polymerization method and dispersing it in water has a surface peeling property. A method of imparting air permeability by applying the composition to a base material having the composition to form a coating film is disclosed. However, depending on the application, there is a demand for a polymer film having even better air permeability.

On the other hand, an adhesive tape used for medical treatment or the like is required to have appropriate air permeability. This is because if it is not breathable, it will cause skin irritation and the like.

Therefore, conventionally, various manufacturing methods have been proposed for making the adhesive tape breathable.

For example, Japanese Patent Publication No. 51-8653 discloses a production method using a dispersion liquid in which a gas or liquid which is not compatible with the pressure-sensitive adhesive is dispersed in the pressure-sensitive adhesive liquid in the form of fine bubbles or liquid bubbles. Has been done. In this method, the surface of the release paper is coated with the dispersion so that the thickness is 1.2 times the diameter of the bubbles or liquid bubbles, and the mixture is heated and dried to break the bubbles or liquid bubbles to form pores. is doing.

Further, JP-B-58-13116 discloses that an adhesive composition using an organic solvent that can be extracted at room temperature with a water-based coagulation extract is applied on a breathable support and then immersed in the extract to remove the organic solvent. A method of extracting and coagulating the pressure-sensitive adhesive composition is disclosed. In this method, a large number of pores are formed in the pressure-sensitive adhesive layer by replacing the organic solvent with water.

Further, in Japanese Examined Patent Publication No. 63-41585, water or a dispersion liquid obtained by uniformly dispersing water and a water-absorbing polymer substance in an organic solvent solution of a rubber-based or acrylic pressure-sensitive adhesive is used as a release sheet. A method of coating, drying and then laminating a porous substrate is disclosed. In this method, by drying the pressure-sensitive adhesive layer in which water is dispersed, the water prevents the adhesive from adhering and an opening is formed in the portion where the water is present.

However, in the method disclosed in Japanese Patent Publication No. 51-8653 and the method disclosed in Japanese Patent Publication No. 63-41585, a gas or liquid that is incompatible with the adhesive to form pores is uniformly formed. It is necessary to prepare a dispersed dispersion liquid or a dispersion liquid in which water or water and a water-absorbing polymer substance are uniformly dispersed. Further, in this dispersion liquid, bubbles, liquid bubbles, water or the like must be maintained in a uniformly dispersed state,
It is not possible to obtain a breathable adhesive tape in which the pores are uniformly dispersed.

Further, in the method disclosed in Japanese Patent Publication No. 58-13116,
Although it is not necessary to prepare the dispersion liquid as described above, since the pressure-sensitive adhesive composition applied to the breathable support is immersed in an aqueous coagulation extract such as water, sufficient breathability is obtained. Difficult to do.

[Problems to be Solved by the Invention]

Therefore, an object of the present invention is to provide a production method capable of stably obtaining a polymer film having further excellent air permeability by a relatively simple process, and a breathable pressure-sensitive adhesive tape or sheet having similar properties. It is an object of the present invention to provide a manufacturing method that enables stable production by simple steps.

[Means for Solving the Problems]

The method for producing a breathable polymer film of the present invention comprises a step of preparing a polymer solution having an interfacial tension with water at 20 ° C. dissolved in an organic solvent of 20 dyn / cm or more, and the polymer solution on the release material surface. The step of applying to form a polymer solution layer, and while the polymer solution layer is in an undried state, water droplets having a particle size of 10 to 1000 μm are added to the surface of the polymer solution layer at a rate of 5 to 200 g / m ² . And a step of drying the polymer solution layer to obtain a polymer film.

Further, the method for producing the pressure-sensitive adhesive tape or sheet of the present invention comprises a step of preparing a pressure-sensitive adhesive solution dissolved in an organic solvent having an interfacial tension with water at 20 ° C. of 20 dyn / cm or more, the pressure-sensitive adhesive solution being a release material. And a step of forming a pressure-sensitive adhesive solution layer on the surface of, and while the pressure-sensitive adhesive solution layer is in an undried state, water drops having a particle size of 10 to 1000 μm are
Characterized by comprising a step of spraying at a rate of 0 g / m ² , a step of drying the pressure-sensitive adhesive solution layer to form a pressure-sensitive adhesive layer, and a step of laminating the pressure-sensitive adhesive layer on a breathable substrate. And

As described above, the production method of the present invention can be applied not only to the breathable pressure-sensitive adhesive tape or sheet, but also to the general method for producing a breathable polymer film. In the following,
First, the details of the method for producing the breathable pressure-sensitive adhesive tape or sheet will be described, and then only the different points regarding the method for producing the breathable polymer film will be described.

Organic solvent that can be used "The interfacial tension with water at 20 ° C used in the present invention is
Examples of the `` 20 dyn / cm or more organic solvent '' include toluene,
Cyclohexane, n-hexane, n-heptane, benzene, iodobenzene, hexadecane, nonylbenzene,
Nonane, carbon disulfide, dodecane, carbon tetrachloride, o, p, m-
Pure solvents such as xylene, octane or ethylbenzene may be mentioned. Further, as the organic solvent, not only the above-mentioned pure solvent but also a mixed solvent obtained by mixing at least two kinds of arbitrary organic solvents may be used. For example, ethyl acetate having an interfacial tension with water of 6.8 dyn / cm and 50.59 dyn / cm
cm is mixed with cyclohexane to increase the interfacial tension with water.
You may use the mixed solvent which was 20 dyn / cm or more. That is, as long as the solvent has an interfacial tension with water of 20 dyn / cm or more, an appropriate mixed solvent can be used.

The interfacial tension of the organic solvent with water is set to 20 dyn / cm or more,
When it is 20 dyn / cm or more, when the sprayed water drops enter the adhesive solution, it easily takes a shape close to a sphere and penetrates deeply in the thickness direction of the adhesive solution layer to create a part where no adhesive exists. Because. On the other hand, when an organic solvent of less than 20 dyn / cm is used, since the interfacial tension with water is small, it is easy to be compatible with water and the water spreads in the surface direction of the pressure-sensitive adhesive layer, forming a part where no pressure-sensitive adhesive exists. Because you cannot do it.

Adhesive Solution As the rubber-based adhesive solution used in the method for producing the adhesive tape or sheet of the present invention, natural rubber or synthetic rubber, rosin-based, terpene-based or petroleum-based tackifying resin, various oils, etc. And a softening agent of the above are dissolved in the above organic solvent.

On the other hand, as the synthetic resin-based adhesive that can be used in the present invention, acrylic acid, acrylamide or N-vinyl-2
An acrylic pressure-sensitive adhesive obtained by copolymerizing a polar monomer such as pyrrolidone and another monomer such as acrylic acid ester, methacrylic acid ester, styrene or vinyl acetate is preferably used. However, other pressure-sensitive adhesives such as polyvinyl-based pressure-sensitive adhesives and polyisobutyl-based pressure-sensitive adhesives can also be used.

Release Material The release material that can be used in the present invention is arbitrary as long as its surface has a release function for the pressure-sensitive adhesive. The most typical one is a release paper or release film which has been treated with silicone. Besides, it is also possible to use a steel belt made of a metal material such as stainless steel, a rotating drum, or the like as the peeling material.

Preparation and Application of Adhesive Solution The above adhesive solution is prepared so as to have an appropriate viscosity. It is preferably prepared to have a viscosity on the order of thousands to 10,000 cps.

Further, the pressure-sensitive adhesive solution and the coating amount on the surface of the release agent differ depending on the pressure-sensitive adhesive and the organic solvent used, but are applied at a rate of about 150 g / m ² . Preferably, it is applied such that the thickness of the adhesive layer after drying is 80 μm or less.

Spraying of Water Droplets Spraying of water droplets onto the surface of the applied pressure-sensitive adhesive solution layer can be carried out using any spraying device such as a spray gun. At the time of spraying, water droplets with a particle size of 10 to 1000 μm, 5 to 200 g / m ²
Is sprayed. This is because the number of pores formed at a rate of less than 5 g / m ² is too small, and when sprayed at more than 200 g / m ² , the density of the pressure-sensitive adhesive layer decreases and the adhesiveness decreases. is there.

Method for producing breathable polymer film In the method for producing the breathable polymer film of the present invention, a polymer solution is used instead of the adhesive solution in the method for producing the adhesive tape or sheet. That is, they are substantially the same except that the pressure-sensitive adhesive solution described above is changed to a polymer solution and that the step of laminating on an air-permeable substrate is omitted. The polymer substance for preparing the polymer solution is not particularly limited. That is, any polymer substance can be used as long as it can be dissolved in an organic solvent having an interfacial tension with water at 20 ° C. of 20 dyn / cm or more.

[Operation and effect of the invention]

According to the method for producing a breathable polymer film of the present invention, 20
Since a polymer solution prepared by dissolving a polymer substance in an organic solvent with an interfacial tension with water at 20 ° C of 20 dyn / cm or more is used, when water droplets are applied to the surface of the polymer solution layer, the water repels the polymer solution. It has a shape close to a sphere and penetrates deeply in the thickness direction of the polymer solution layer to form a portion where no polymer substance exists. Therefore, by drying and removing water, pores are formed in the portion where water was present. Therefore, it is possible to obtain a polymer film having excellent air permeability in a simple process.

Further, according to the method for producing a pressure-sensitive adhesive tape or sheet of the present invention, since the interfacial tension with water at 20 ° C. uses a pressure-sensitive adhesive solution dissolved in an organic solvent having 20 dyn / cm or more, it is sprayed on the surface of the pressure-sensitive adhesive solution layer. The water thus formed repels the pressure-sensitive adhesive solution while entering the pressure-sensitive adhesive solution layer and takes a shape close to a sphere.
Therefore, water penetrates deeply in the thickness direction of the adhesive solution layer,
Form a part where no adhesive is present. Therefore, pores are formed in the pressure-sensitive adhesive layer by drying and removing water.

That is, in the method of the present invention, a pressure-sensitive adhesive tape or sheet having stable and sufficient air permeability is applied by each simple step of applying the above-mentioned pressure-sensitive adhesive solution to the surface of the release material, spraying water droplets and then drying. Obtainable.

Use of the present invention The method for producing a breathable polymer film of the present invention can be used to obtain a product such as a hygiene product film, a food packaging film or a polymer filtration membrane.

Further, the present invention can be applied to general production of pressure-sensitive adhesive tapes or sheets that require air permeability, and is particularly preferably used for production of medical pressure-sensitive adhesive tapes or sheets.

[Examples] Hereinafter, non-limiting examples of the present invention will be described.

Example 1 2 Monomer composition consisting of 80 parts by weight of ethylhexyl acrylate, 8 parts by weight of ethyl acrylate, 7 parts by weight of N-vinyl-2-pyrrolidone, 4.8 parts by weight of acrylic acid, and 0.2 parts by weight of 2-hydroxyethyl acrylate. The product was treated with toluene (interfacial tension with water at 20 ° C: 36.25 dyn / c
m) was polymerized, and the solid content was adjusted to 40% to prepare an adhesive solution. The viscosity of this solution was 6000 cps.

Next, the above-mentioned pressure-sensitive adhesive solution was applied on a release paper at a rate of 150 g / m ² to form a pressure-sensitive adhesive solution layer, and while the pressure-sensitive adhesive solution was not dried, the particle size was 100 to 200 μm on its surface. 75 water particles
Spray and dry at a rate of g / m ² ,
An adhesive layer was formed.

Next, this pressure-sensitive adhesive layer was transferred to a breathable base material (Tetron nonwoven fabric; manufactured by DuPont) to obtain a breathable pressure-sensitive adhesive tape.

The air permeability of the obtained air-permeable pressure-sensitive adhesive tape was measured using a denso meter.
It took 0.8 seconds.

Comparative Example 1 Lauryl mercaptan was added to the same monomer composition as in Example 1.
The composition added with 0.05 parts by weight was polymerized with ethyl acetate (interfacial tension with water at 20 ° C was 6.8 dyn / cm) to obtain a solid content of 40%.
To obtain an adhesive solution. The viscosity was 6000 cps.

Next, using the above adhesive solution, in the same manner as in Example 1,
It was applied to one surface of release paper, sprayed with water, dried, and transferred to a breathable base material to obtain an adhesive tape.

When the air permeability of the obtained adhesive tape was measured with a densometer as in Example 1, it took 25 seconds for 300 cc of air to pass through.

Example 2 80 parts by weight of 2-ethylhexyl acrylate, 8 parts by weight of ethyl acrylate, and N-vinyl-2-pyrrolidone 7
By weight, a monomer composition consisting of 4.8 parts by weight of acrylic acid and 0.2 parts by weight of 2-hydroxyethyl acrylate is polymerized with cyclohexane (interfacial tension with water: 50.59 dyn / cm) to obtain a solid content of 40%. Thus, ethyl acetate was mixed to obtain an adhesive solution. The weight ratio of the organic solvent is cyclohexane: ethyl acetate = 75: 25. The viscosity of the obtained pressure-sensitive adhesive solution was 8000 cps.

Next, the pressure-sensitive adhesive solution was applied on a release paper at a rate of 150 g / m ² to form a pressure-sensitive adhesive solution layer, and while the pressure-sensitive adhesive solution layer was not dried, a particle size of 100- 200 μm water particles
It was sprayed and dried at a rate of 75 g / m ² .

Next, the obtained pressure-sensitive adhesive layer was transferred to a breathable substrate (Tetron nonwoven fabric; manufactured by DuPont) to obtain a breathable pressure-sensitive adhesive tape.

When the air permeability of this air-permeable pressure-sensitive adhesive tape was measured using a denso meter, it took 1.0 seconds for 300 cc of air to pass through.

Example 3 Polymethylmethacrylate was dissolved in toluene to obtain a 20% by weight polymer solution. This polymer solution was applied onto a stainless steel endless belt at a rate of 50 g / m ² , and the toluene solution layer of the polymethylmethacrylate was 20 to 20
30 μm water particles were sprayed at a rate of 50 g / m ² and then dried in a drying oven to obtain a porous polymethylmethacrylate film.

When observing this film with a transmission optical microscope, 4m
15 holes of 50 to 100 μm were observed per m ² .

Example 4 Polyvinyl chloride containing 60 parts by weight of dioctyl phthalate as a plasticizer was dissolved in a mixed solvent of toluene: methyl ethyl ketone (weight ratio 6: 4) to obtain a 20% by weight polymer solution. This polymer solution was applied onto a stainless steel endless belt at a rate of 150 g / m ² to form a toluene solution layer of polyvinyl chloride.

Next, from the top of the toluene solution layer of polyvinyl chloride 100 ~ 3
After water particles of 00 μm were sprayed at a rate of 150 g / m ² , they were dried in a drying oven to obtain a porous soft vinyl chloride film.

When the air permeability of this film was measured with a denso meter, it took 0.3 seconds for 300 cc of air to pass through.

Claims (6)

[Claims] 1. A step of preparing a polymer solution dissolved in an organic solvent having an interfacial tension with water at 20 ° C. of 20 dyn / cm or more, the polymer solution being applied to the surface of a release material having a releasability. A step of applying to form a polymer solution layer, and 5 to 200 g / m ² of water droplets having a particle size of 10 to 1000 μm on the surface of the polymer solution layer while the polymer solution layer is in an undried state.
A method for producing a breathable polymer film, which comprises a step of spraying and a step of drying the polymer solution layer to obtain a polymer film. 2. The method for producing a breathable polymer film according to claim 1, wherein a mixed solvent is used as the organic solvent. 3. The method for producing a breathable polymer film according to claim 1, wherein a metal drum is used as the release material. 4. The method for producing a breathable polymer film according to claim 1, wherein an endless belt is used as the release material. 5. A step of preparing a rubber-based or synthetic resin-based pressure-sensitive adhesive solution dissolved in an organic solvent having an interfacial tension with water at 20 ° C. of 20 dyn / cm or more, and the pressure-sensitive adhesive solution on the surface of a release material. A step of applying to form a pressure-sensitive adhesive solution layer, and while the pressure-sensitive adhesive solution layer is in an undried state, water droplets having a particle size of 10 to 1000 μm are added to the surface of the pressure sensitive adhesive solution layer to 5 to 200 g / m ^2.
A step of spraying, a step of drying the pressure-sensitive adhesive solution layer in which the water droplets are sprayed to obtain a pressure-sensitive adhesive layer, and a step of laminating the pressure-sensitive adhesive layer on a breathable substrate. And a method for producing a breathable adhesive tape or sheet. 6. The method for producing a breathable pressure-sensitive adhesive tape or sheet according to claim 5, wherein a mixed solvent is used as the organic solvent.