JP2000218709A - Water responsive resin deforming method, water responsive deforming resin, and water responsive air permeable film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a method for deforming a resin molded article into a specific shape by water swelling, a water responsive deforming resin to be deformed by this method, and a water responsive air permeable film for deforming vent holes corresponding to moisture quantity or humidity to perform the regulation of ventilation quantity or waterproofness. SOLUTION: At the time of swelling of a water swellable resin molded article, the swelling of a part of the molded article is suppressed by utilizing a difference in swelling ratio and the molded article is deformed. A water responsive deforming resin is obtained by bonding a molded article of which the swelling ratio is less than that of a resin molded article to the water swellable resin molded article. A water responsive air permeable film is obtained by bonding a film 4 of which the swelling ratio is smaller than that of a water swellable resin film 3 to the single surface of the film 3 and providing piercing vent holes 5 projected from the single surface of the film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of deforming a resin molded article by a difference in swelling ratio by utilizing the water swelling property of a superabsorbent polymer at the time of water absorption, and a water-sensitive deformable resin deformed by the method. Further, the present invention relates to a water-sensitive breathable film that deforms a ventilation hole and adjusts a ventilation amount.

[0002]

2. Description of the Related Art Heretofore, there has been a water-swellable resin in which a highly water-absorbing polymer is blended with various resins such as synthetic resins and natural rubbers and used as a swelling component. Some of the breathable films were provided with a large number of ventilation holes in the film.

[0003]

A conventional water-swellable resin molded product in which a highly water-absorbing polymer is uniformly blended has a property that the whole is substantially uniformly volume-expanded by swelling due to water absorption. However, in order to deform the molded product into a specific shape at the time of volume expansion, it is necessary to apply an external force or use a mold or the like. In addition, conventional breathable films do not have the function of adjusting the ventilation rate by changing the size of the ventilation holes, so that humidity control and moisture control corresponding to changes in humidity and moisture at locations separated by the film can be performed. There is a problem that it is not suitable for purposes such as waterproofing. Furthermore, since the structure intended for waterproofing in addition to ventilation has a structure in which the ventilation holes are made fine and water droplets are difficult to pass through, sufficient ventilation cannot be expected regardless of the presence or absence of moisture.

In view of the above problems, the present invention utilizes a water swelling property of a superabsorbent polymer without using an external force or a mold to specify a water-swellable resin molded product by a difference in swelling ratio at the time of water absorption. An object of the present invention is to provide a method for deforming into a shape, a water-sensitive deformable resin deformable by the method, and a water-sensitive gas-permeable film that adjusts the amount of air flow by deforming a vent according to the amount of water absorption.

[0005]

In order to achieve the above object, the water-sensitive resin deformation method of the present invention focuses on the water swellability of a superabsorbent polymer, and uses a water-swellable resin containing the superabsorbent polymer as a swelling component. In the case of swelling of a molded product, that is, volume expansion due to water absorption, expansion of a part of the resin molded product is suppressed by utilizing a difference in swelling ratio, and the molded product is deformed.

The water-sensitive deformable resin utilizing the above method is obtained by adhering a molded product having a swelling ratio smaller than that of the molded resin to a water-swellable resin having a superabsorbent polymer as a swelling component. It is characterized by being deformed by the difference of the swelling ratio at the time of volume expansion.

[0007] Even when the superabsorbent polymer is unevenly distributed in a resin molded product mainly composed of various resins such as synthetic resin and natural rubber, uneven distribution of swelling ratio is generated,
The same effect as described above can be obtained by the difference between the swelling ratios.

[0008] A water-sensitive breathable film utilizing the above characteristics is obtained by bonding a film having a lower swelling ratio to one surface of a water-swellable resin film containing a super-water-absorbing polymer as a water-swelling component. A through-hole having a shape protruding from the surface is provided.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on embodiments with reference to the drawings.

FIG. 1 shows an embodiment for explaining the characteristics of the water-sensitive resin deformation method and the water-sensitive deformation resin of the present invention.
Fig. 2 is a perspective view of a water-swellable resin molded product 1 having a super-water-absorbing polymer as a swelling component and a molded product 2 having a swelling ratio smaller than that of the molded product 1 bonded thereto, and Fig. 2 is a sectional view thereof.

The superabsorbent polymer serving as the swelling component is also referred to as a superabsorbent polymer or a superabsorbent polymer, and is roughly classified into starch, cellulose, and synthetic polymer based on the raw material. These generally have a water-absorbing capacity of 100 times or more of their own weight, and water swelling properties in which the volume expands according to the amount of water absorption,
It has high swelling gel strength and swelling power when absorbing water.

Regarding the compounding with the resin, the superabsorbent polymer can be compounded with most resins such as synthetic resins and natural rubbers, and there are also compounds in which the superabsorbent polymer is compounded with various resins. Because it is easy, it is possible to select a resin and a superabsorbent polymer suitable for the purpose of use. In addition, in order to enhance the swelling response, it is effective to mix it with a soft resin. Further, among the superabsorbent polymers, those which can be formed and processed alone need not necessarily be blended with another resin.

Molded product 2 having a swelling ratio smaller than resin molded product 1
Is obtained by processing and molding various resins, paper, metal, natural fibers, and the like as a main composition, and can be used as long as it can be deformed by swelling of the resin molded product 1. The swelling ratio of the molded article 2 may be smaller than that of the molded article 1, and may be 0 or negative.

The shape of the water-sensitive deformable resin is not particularly limited, and may be any shape depending on the application. For example, it may be plate-like, rod-like, coil-like, fibrous, or a processed product thereof. As for the responsiveness, the thinner the thickness, the better.

Due to the above-mentioned characteristics, the water-swellable resin molded article 1 shown in FIGS.
Due to the difference in the swelling ratio from the above, deformation occurs as shown in FIG. This effect is similar to, for example, a bimetal utilizing a difference in coefficient of thermal expansion.

Even if the superabsorbent polymer is unevenly distributed in a resin molded product containing various resins such as synthetic resin and natural rubber as a main composition, the polymer is deformed due to a difference in swelling ratio of each part at the time of water absorption. The effect of can be obtained. FIG. 4 is a cross-sectional view of a resin molded product in which a superabsorbent polymer is unevenly distributed on one side as one example.

FIG. 5 shows an embodiment of a water-sensitive breathable film utilizing the above-mentioned characteristics. The swelling ratio of one side of a film 3 formed from a water-swellable resin containing a superabsorbent polymer as a swelling component is higher than that of the film 3. A small film 4 is adhered, and a part of a cross section of a water-sensitive breathable film provided with a through-hole 5 projecting from the surface on the film 3 side is enlarged.

As described above, when the film 3 expands due to water absorption, the difference in the swelling ratio with the film 4 causes the air holes 5 to be deformed in the direction of contraction. As a result, the ventilation amount is adjusted according to the change in the size of the ventilation hole 5, and a humidity control effect at a location separated by the breathable film and a waterproof effect by sealing the ventilation hole are generated. In a relatively dry environment, the size of the ventilation hole 5 is close to the maximum, so that sufficient ventilation can be expected. When moisture is released, the vent expands due to the adverse effect. When the air holes protrude from the surface on the film 4 side, the air holes are deformed in the expanding direction when water is absorbed, contrary to the above.

The shape, number, and size of the ventilation holes can be selected according to the purpose. For example, as for the shape, the one whose cross-sectional shape at the time of opening can be easily deformed such as a spindle, polygon, or star has a response. Good nature. FIG. 6 is an enlarged plan view of a part of a breathable film in which the shape of the vent hole 5 is a spindle as an example.

The water-sensitive air-permeable fill may be formed by molding the water-sensitive deformable resin according to claim 3 into a film shape and providing a vent hole protruding on one side.

[0021]

The present invention has the following effects.

In the water-sensitive resin deforming method according to the first aspect and the water-sensitive deformable resin according to the second and third aspects, resin molding is performed by a difference in swelling ratio at the time of water absorption without applying external force or regulating expansion by a mold. An object can be deformed to a specific shape.

In the water-sensitive breathable film of the fourth aspect, the ventilation hole can be deformed according to the amount of moisture and humidity to control the amount of ventilation. In addition, waterproofing by sealing the ventilation holes is also possible.

In the case where a part of the surface of the water-sensitive breathable film according to the fourth aspect comes into contact with moisture, it is possible to locally regulate the ventilation of the water-absorbing portion of the film and its peripheral portion.

The water-sensitive breathable film according to the fourth aspect, in which the air holes are reduced by swelling, can improve the air permeability in a dry and low humidity state as compared with the conventional air-permeable waterproof film.

The water-sensitive breathable film according to claim 4 is a breathable leakproof film for disposable diapers and sanitary products, a breathable material for clothing, a breathable packaging material, a breathable ceiling material adhered to a breathable plate or the like. It can be used as a material for ventilation control, including wood and flooring.

[Brief description of the drawings]

FIG. 1 is a perspective view of a water-sensitive deformable resin before deformation.

FIG. 2 is a sectional view of a water-sensitive deformable resin before deformation.

FIG. 3 is a cross-sectional view of a water-sensitive deformable resin after deformation.

FIG. 4 is a cross-sectional view of a resin molded product in which a superabsorbent polymer is unevenly distributed.

FIG. 5 is a cross-sectional view of a water-sensitive breathable film.

FIG. 6 is a plan view of a breathable film having spindle-shaped vent holes.

[Explanation of symbols]

 Reference Signs List 1 water-swellable resin molded product 2 molded product with swelling ratio smaller than 1 3 water-swellable resin film 4 film with swelling ratio smaller than 3 5 vent hole

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 4F071 AA01 AA08 AA09 AF04 AH03 BC02 4F100 AK01B AL05B AT00A AT00B BA02 BA44 BA44B DC11 EJ33 GB07 GB15 GB66 GB72 JB05 JB05B JB10 JB10A JB10B JD02 JK08 AD03 A0306

Claims (4)

[Claims] When the volume expansion of a water-swellable resin molded article containing a super-water-absorbing polymer as a swelling component is caused by water absorption, the expansion of a part of the resin molded article is suppressed by utilizing a difference in swelling ratio, A method for deforming a water-sensitive resin, comprising deforming a molded product. 2. A water-sensitive deformable resin comprising a water-swellable resin molded product (1) containing a superabsorbent polymer as a swelling component and a molded product (2) having a swelling ratio smaller than that of the resin molded product (1). 3. A water-sensitive deformable resin in which a superabsorbent polymer is unevenly distributed in a resin molded product. 4. A film (4) having a swelling ratio smaller than that of the water-swellable resin film (3) having a superabsorbent polymer as a swelling component is adhered to one surface of the water-swellable resin film (3), and protruded from one surface of the adhered film. A water-sensitive breathable film provided with a through-hole (5).