JPH0257330A - Hygroscopic sheet - Google Patents

Abstract

PURPOSE:To obtain a method having excellent economical production by thermally covering by hot rolling a nonhydrophilic plastic film at least on one side face of a hygroscopic sheet, and providing numerous fine pores at the film. CONSTITUTION:A hygroscopic sheet is coated by hot rolling with a nonhydrophilic plastic film. The film is melted at the time of hot rolling, momentarily intruded into the hygroscopic paper on the surface layer of the sheet to fusion-adhere thereto. Then, when it is pressed by a roll or a plate having numerous styluses, numerous fine pores can be easily provided at the film.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a water absorbent sheet with excellent productivity and economic efficiency.

(Prior art and its problems) Water-absorbent sheets are used as the main part of disposable diapers or sanitary products, and are used to absorb drips from food to increase its shelf life, and to adjust moisture content and prevent fluctuations in it. It is used in many ways to reduce the amount of water and increase the preservation of moisture-containing products, such as foods, fresh flowers, textile products, and leather products.

This water-absorbing sheet is made of highly water-absorbing materials such as water-absorbing paper, water-absorbing fibers, water-absorbing polymer resins, polysaccharides, sugars, and glues, either singly or in combination. For molecular resins, polysaccharides, and saccharides that are difficult to form into sheets by themselves, they may be sandwiched between water-absorbing paper or water-absorbing fiber cloth, or between hydrophilic plastic films such as POVAL. It is usually made as a sandwich.

However, water-absorbing sheets made by these methods, for example, when the surface layer is water-absorbing paper, have the problem that when water is absorbed, the water-absorbing paper peels off, or the water-absorbing agent inside oozes out, making it unusable. However, as a countermeasure to this, there are products that are further wrapped in cloth, which solves this problem, but not only is the cloth expensive and time-consuming to produce, but the wrapping process is also troublesome, making it difficult to produce and economically. I don't like it either.

When the surface layer is made of poval, when it is necessary to absorb a large amount of water, such as in diapers, there is a problem that some of the poval dissolves and sticks to the skin, causing discomfort.

When the surface layer is made of nonwoven fabric, cloth, etc., the above-mentioned problems do not occur, but as described above, productivity is poor and the material is expensive, which is not preferable.

(Means for Solving the Problem) In order to solve this problem, the present invention has succeeded in changing the way of thinking and creating a method that is extremely economical and productive.

That is, the present invention is a water-absorbing sheet in which at least one side of the water-absorbing sheet is coated with a non-hydrophilic plastic film by hot rolling, and the film is provided with countless micropores.

In the present invention, since a non-hydrophilic plastic film is heat-rolled and coated on a water-absorbent sheet, the film melts during heat-rolling and instantaneously sinks into the water-absorbing paper on the surface layer of the water-absorbent sheet and fuses.

Then, by pressing the film with a roll or branch having countless needles, it is possible to easily form countless micropores in the film.

Therefore, water is absorbed into the water-absorbing sheet through the film's countless micropores, and no water droplets remain on the film surface.Since the film is non-hydrophilic, it does not change, and the water-absorbing paper does not get damaged.

Moreover, it is extremely favorable both in terms of productivity and economy.

Another method is to first press a non-hydrophilic plastic film with a roll or plate having countless needles to form countless micropores, and then heat-roll and coat the film on a water-absorbing sheet.

However, in the former method, a non-hydrophilic plastic film is heat-rolled and then pierced with countless needles at room temperature to form countless micropores. It can be made into any size, and since it is a needle, the tip is sharp and can reliably form extremely small microholes.

On the other hand, in the latter method, a countless number of micropores are formed and then the coating is heated and rolled, so that the needles are simply inserted into the water-absorbent sheet, and the needles do not pierce the water-absorbent sheet.

Typical resins for nonaqueous plastic films include polyolefin-based resins, particularly polyethylene-based, vinyl chloride-based, and vinylidene chloride-based resins, and polyolefin-based resins are the most effective.

The fact that the plastic film is heat-rolled and coated on at least one side of the water-absorbent sheet means that the plastic film is coated on one side, both sides, or the entire surface of the water-absorbent sheet. ,
In addition to this, it is sufficient that the water-absorbing sheet has countless micropores provided on the surface that absorbs water, and the film that covers the surface where the water-absorbing sheet absorbs water may have numerous micropores. If the water absorbent sheet is not provided, the water absorbed by the water absorbent sheet will accumulate within the water absorbent sheet and will not go out to other surfaces. Therefore, if you do not want other surfaces to get wet, for example, This is extremely preferable when it is necessary to seal a moisture-containing product to prevent moisture from entering the interior. When coating both sides, different films may be used.

This container or bag can be used for foods, fresh flowers, textile products, etc.
Effective for preserving or treating moisture-containing products such as leather products and dirty items.

The method of creating countless micropores in a plastic film is as follows.
Although exemplified as described above, any method may be used as long as the object of the present invention can be achieved.

When the water-absorbent sheet, which is the core material of the water-absorbent sheet of the present invention, contains zeolite or (and) fine ceramic powder that easily emits far-infrared rays with a wavelength of 6 to 14 microns,
The effects of the present invention are even more significant.

If the water-absorbent sheet contains fine ceramic powder that easily emits far-infrared rays with a wavelength of 6 to 14 microns, this specific far-infrared rays will be constantly emitted to the water absorbed by the water-absorbent sheet, activating the water. This means that there is no chance of spoilage as in the past.

Moreover, not only that, but also water-containing products such as food,
When this water-absorbing sheet is applied to fresh flowers, filth, etc., it activates the water content and controls the humidity, increasing the shelf life, and also deodorizes and improves odor.

It is also known that food products, fresh flowers, etc. have a longer shelf life if they are stored in a state where their moisture is retained, especially if they are stored in a cooled state. However, if the storage period is prolonged, the water-containing material deteriorates due to aging, and the flavor and texture become undesirable. This tendency is particularly strong when stored at room temperature.

Furthermore, if the food is cooled too strongly and frozen, the quality often deteriorates and the flavor and texture become undesirable.

Furthermore, even if there is no deterioration in quality during freezing, the liquid material oozes out during thawing and becomes drips, which further deteriorates the quality of the water-containing material during thawing and rapidly deteriorates the flavor and texture.

This can be significantly improved by using the present water absorbent sheet.

Next, when zeolite is contained instead of the ceramics, since zeolite has bactericidal, hygroscopic, deodorizing, and ion exchange properties, the rot caused by moisture in the water absorbent sheet is further significantly improved. Ru.

The surface of the water-absorbent sheet is also sterilized, which further prevents moisture from spoiling the entire sheet, thereby greatly increasing the shelf life of foods, fresh flowers, etc.

By using the zeolite and ceramics together,
This effect becomes even greater.

Ceramics that easily emit far-infrared rays are suitably made into fine powders of natural or synthetic material, especially those made porous. Those mainly composed of zirconia, alumina, silica, etc. are preferred, and those that emit far infrared rays with a wavelength of 6 to 14 microns, preferably 8 to 12 microns, are most effective.

Products from Shinsei Bio Co., Ltd. and Nippon Serum Co., Ltd. are common.

The fine zeolite powder is suitably natural or synthetic zeolite, Oya stone, or its analogues. In addition, divalent or higher valent metals such as Ni, Co, Ag, Ca, Zn, Zr, Au,
If ions such as these are adsorbed alone or in combination and subjected to ion exchange, the bactericidal properties will be further strengthened.

A method for incorporating ceramics or (and) zeolite into a water-absorbing sheet is, for example, by adding porous fine powder thereof before, during, or after making the water-absorbing sheet.

The weight percent of the total amount of ceramics or (and) zeolite added to the water absorbent sheet is 0.5% by weight based on the water absorbent sheet.
% or more is suitable, and if it is less than 0.5%, the main effect will be difficult to appear. Although the upper limit varies depending on the material and structure of the water-absorbing sheet, the higher the upper limit, the greater this effect will be. However, as the number increases, problems may arise in terms of strength, so it is important to take this into consideration when making a decision. Approximately 30% is normal.

Example: 1. Add sodium acrylate based super water absorbent resin powder to blotting paper.
0% zeolite fine powder and 2% ceramic fine powder that easily emits far infrared rays with a wavelength of 8 to 12 microns are thoroughly mixed under low humidity and then laminated, and then blotting paper is further laminated on top of that and then pressure bonded. Then, spray lightly with water vapor and dry.

Next, a polyethylene film made by adding 2% zeolite to polyethylene and using a conventional method is applied to cover the entire surface by lightly thermocompression bonding.

Next, the polyethylene film is passed through a roll having numerous needles to form numerous micropores on one side of the polyethylene film.

Next, this was cut to an appropriate size, the surfaces having countless micropores were placed together, the following water-containing product was inserted between them, and the entire line was then heat-sealed to seal.

These are stored refrigerated at about 5°C for 20 days.

For comparison, a test was conducted in exactly the same manner using a water absorbent sheet using only the above-mentioned absorbent paper without using any zeolite or ceramic fine powder and not covered with a polyethylene film.

The water-containing products used are as follows.

Group 1 1-1 Fresh vegetables, 1-2 Beef pieces, 1-3
2 groups of tuna cut into strips 2-1 Dog excrement, 2-2 Sludge The present invention is significantly fresher and has a longer shelf life than the comparative product for Group 1, and there is no paper or water absorbing agent attached to the food. It was clearly superior.

In addition, the two groups were also sufficiently deodorized, and there was a clear difference.

Claims (1)

[Claims] 1. A water-absorbent sheet, wherein at least one side of the water-absorbent sheet is heat-rolled and coated with a non-hydrophilic plastic film, and the film is provided with countless micropores.