JPH03213579A - Production of porous film and moisture-permeable sheet material produced by mutually same method - Google Patents

Abstract

PURPOSE:To obtain a porous and moisture-permeable sheet material by applying a resin solution comprising a synthetic resin and powder obtained with heating and pressing a piece of natural leather in a sealed vessel, swelling under reduced pressure and finely crushing to a base material, coagulating and eluting a part of the leather powder with warm water. CONSTITUTION:A piece of natural leather in a sealed vessel is heated and pressed, then, the vessel is instantaneously opened to make reduced pressure to swell said leather piece, thus dried and finely crushed to obtain leather powder. Next, the leather powder is mixed into a synthetic resin (e.g. polyurethane resin) solution. Then, a base material, e.g. a paper pattern, woven cloth, nonwoven cloth or leather, is applied or impregnated with said resultant solution, thus coagulated and a part of said leather powder is eluted by warm water or hot water to form a porous film having excellent flexibility, moisture permeability and moisture absorbing and ejecting properties. Otherwise, a moisture- permeable sheet material having the above-mentioned properties is obtained.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is directed to a method of making a synthetic resin film into a porous structure and, by using the method, a resin film with excellent moisture permeability, moisture absorption and drainage properties, and a soft feel. The present invention provides a film, a painted surface, and a moisture-permeable sheet material having these properties.

(Prior art) In order to create a resin film with a porous structure, there are two methods: mixing starch, etc. into the resin and then eluting it;
There have been methods such as using a decomposable foaming agent or generating gas during the polymerization process of the resin to cause foaming.

However, even if the resin film is made porous using these conventional methods, most of the cells will be closed cells or open cells. Therefore, the resin films and resin coatings produced in this manner lack moisture permeability, moisture absorption and drainage properties, feel cool to the touch, and are far from meeting the requirement of having a texture similar to that of natural products.

(Means for Solving the Problems) The characteristic means of the present invention is to simultaneously heat and pressurize a piece of natural leather with steam in a sealed pressure vessel, and then momentarily open the pressure vessel to depressurize the piece of leather. The leather powder obtained by swelling, drying, and pulverization is mixed into a synthetic resin liquid, and the synthetic resin liquid is applied to the target substrate, or after the target substrate is immersed in the synthetic resin liquid, the synthetic resin liquid is mixed. By coagulating it and immersing it in warm water or boiling water to dissolve some of the leather powder, a resin film with a fine porous structure on the micron scale is created, and the remaining undissolved leather powder is It imparts unique properties such as moisture absorbing and desorbing functions and moisture permeability. Another object of the present invention is to produce a fibrous sheet material having moisture absorbing and discharging properties, moisture permeability, etc. by this manufacturing method.

(Function) The present invention utilizes the property that when moist leather is exposed to an atmosphere of high-temperature steam, part of the collagen that makes up the leather has physical properties close to gelatin, and that it dissolves relatively easily in hot or boiling water. When a piece of natural leather containing moisture is heated and simultaneously pressurized with steam in a sealed pressure vessel, the inside of the container becomes hot and humid, and after a certain period of time, the leather piece is separated from the gelatinized part and the unmodified part. degenerates into collagen tissue. Note that the higher the moisture content and steam pressure of this leather piece, and the longer the retention time in the pressure vessel, the higher the conversion rate of collagen to gelatin. Next, when the pressure vessel is momentarily opened and the pressure is reduced, the leather piece is swollen due to the rapid expansion of high-temperature, high-pressure water contained within the leather tissue of the leather piece.

As a result of this swelling, the leather piece is subdivided into fine mixed particles of collagen and gelatin, so the leather powder obtained by drying and pulverizing this becomes an extremely uniform mixture of collagen and gelatin.

In addition, since the collagen tissue of the puffed leather piece is fragmented, it is extremely easy to pulverize into fine particles, and the pores inside the leather tissue are expanded, so the leather piece is dried and
Leather powder obtained by fine pulverization has a significantly increased specific surface area compared to leather powder obtained by simply pulverizing leather pieces without any of these treatments, and is more easily dissolved in hot or boiling water. Therefore, this leather powder is mixed into a synthetic resin liquid, the synthetic resin liquid is applied to the target substrate, or the target substrate is immersed in the synthetic resin liquid, the synthetic resin liquid is solidified, and then the target substrate is coated with the synthetic resin liquid. If you soak it in warm or boiling water to elute only the gelatin,
The traces of melting remain in the form of microscopic pores, making it possible to obtain an extremely uniform and fine porous structure.

This makes it possible to create a resin film that has a soft feel, is highly flexible, and has excellent moisture permeability. In addition, the undissolved leather powder mainly composed of collagen is exposed on the surface of the film and the walls of the pores, bringing about the unique properties of natural leather, such as moisture absorption and drainage functions and moisture permeability. A resin film with a soft texture and color tone can be obtained. Furthermore, paints made by adding pigments to synthetic resin liquid or mixing leather powder to ready-made synthetic resin paints are applied to objects such as metal, wood, resin, and paper by methods such as spraying, coating, and dipping. After forming the leather, it is soaked in hot water or boiling water to dissolve some of the leather powder, resulting in a fine porous structure on the micron scale.
A coating film with excellent moisture permeability, a soft texture and excellent color tone can be obtained.

(Effects of the Invention) As described above, according to the present invention, it is possible to produce resin films and paint films that have a softer feel than conventional ones, are rich in flexibility, and have excellent moisture permeability and moisture absorption and drainage properties. In addition, the physical properties of the leather powder itself can be changed depending on the processing conditions for swelling and finely pulverizing the leather during the manufacture of the leather powder, and the mixing ratio of the leather powder in the synthetic resin liquid and the adjustment of the hot water or boiling water treatment can be adjusted to prevent airflow. It has become possible to obtain resin films or coatings suitable for the purpose of use by arbitrarily adjusting moisture absorption and drainage properties.

(Example 1) Shaving waste containing 49% water was put into a sealed container,
Steam with a pressure of 3.1 kg/cr& is fed into the container for 6 minutes to heat and pressurize at the same time, then the pressure container is momentarily opened and decompressed to swell the leather, and after drying, it is coarsely crushed with an impact crusher. A leather powder containing 66% of 32 mesh or less was obtained. This leather powder was further finely pulverized with a jet mill, and the specific surface area was 8.
300 an! /gr of leather powder was obtained. Next, a mixed paint made by mixing this leather powder into a paint whose main component is polyurethane resin at a weight ratio of 20% based on the resin solid content is applied to the wallpaper base material and dried to form a paint film. After that, the coating film was immersed in warm water at 100° C. for 15 minutes and dried, resulting in the formation of numerous microscopic pores in the coating film, forming a coating film with a porous structure. The resulting wallpaper had moisture absorbing and discharging properties, a soft surface, and a subdued color tone.

(Example 2) The same leather powder as in Example 1 was mixed into a polyurethane resin liquid at a weight ratio of 40% based on the resin solid content, and this was applied to a fibrous base material and dried to produce a fibrous sheet material. Next, when this was immersed in 100°C warm water for 15 minutes,
Gelatinous material corresponding to about 25% of the leather powder was eluted, and after drying, fine pores were left behind, yielding a fibrous sheet material with a porous structure. As a result of the test, the fibrous sheet material has sufficient moisture permeability, water absorption and water absorption properties, flexibility, and tensile strength, and has a soft feel, and has excellent features not seen before as a moisture permeable sheet material. Ta.

(Other Examples) Target substrates in the present invention include textile products such as woven fabrics, non-woven fabrics, artificial leather, synthetic leather, and natural leather, as well as synthetic resins, wood, bamboo, metals, and ceramics. It is possible. The synthetic resin may be a thermoplastic resin, and any type of natural leather powder can also be used. In addition to leather powder, pigments and other paint components may be added to the synthetic resin liquid. Further, a blowing agent may be mixed into the synthetic resin, which is effective when forming a relatively thick film or coating.

It should be noted that the product produced by implementing the present invention, its use, processing method, etc. are not limited.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an outline of the moisture permeable sheet material according to this example. In the figure, 1...polyurethane resin, 2...
...Leather powder, 3...Vacancies, 4...
・It is a fiber base material.

Claims (2)

[Claims] (1) Synthesis in which a piece of natural leather is heated and pressurized with steam in a sealed container, and then the pressure container is instantly opened and decompressed to swell, dry, and finely pulverize the obtained leather powder. Apply a resin liquid to the target base material or immerse the target base material in a synthetic resin liquid, and after solidifying the synthetic resin liquid, immerse it in warm or boiling water to dissolve some of the leather powder and form a resin film. A method for producing a porous film characterized by having a porous structure. (2) Applying the synthetic resin liquid of claim 1 to a fiber base material or immersing the fiber base material in the synthetic resin liquid, solidifying the synthetic resin liquid, and then soaking it in warm or boiling water to form a leather powder. A moisture-permeable sheet material characterized by having a resin film with a porous structure by partially eluting it.