JPS5940405Y2 - Water absorbent material - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a water-absorbing material such as a diaper or a sanitary napkin that has a large water-absorbing power and is compactly constructed.

BACKGROUND ART Conventionally, multilayered tissue paper, fluff pulp, and the like have been used as absorbent layers for so-called disposable diapers and napkins.

However, since these are absorbent materials that absorb water by retaining it in the gaps between the fibers, they are bulky, and if you try to obtain a sufficient amount of water absorption, the product will not only be thick, but also compressed after absorbing water.
Otherwise, the water is squeezed out again, causing discomfort during use and causing cuffing.

On the other hand, since around the 1920s, it has been proposed to use a type of water-absorbing substance that forms a gel when it absorbs water and swells, trapping water within the gel structure.

This water-absorbing substance not only can absorb a large amount of water, but also has favorable properties in that the absorbed water is not released even when it is immersed.

However, in order to effectively utilize these substances,
It is necessary to transport the liquid supplied to the material evenly to the surface of these materials, and even though there are difficulties in solving this problem, it has hardly been put into practical use.

Recently, it has been proposed to form a sheet by mixing particles of the water-absorbing substance and pulp fibers.

This is an advance in that the absorbent layer can be formed compactly and the water-absorbing substance described above can be used effectively to some extent.

However, since the pulp fiber layer is originally spot-absorbent, it cannot sufficiently diffuse the liquid, leaving a large amount of water-absorbing material that remains unused, and because the absorbent layer is made into a sheet, the product becomes hard and feels bad to the touch. I can't say it's satisfactory.

In view of the above-mentioned points, the present invention aims to provide a material that is compact, has excellent water absorption power, and has a good texture by devising the structure of the water-absorbing material. For example, the water absorbent material 1 of the present invention comprises an absorbent layer unit 5 in which a short fiber flank layer 2, a tissue paper layer 3, and a water absorbent sheet layer 4 are stacked in this order, and the water absorbent sheet layer 4 is a short fiber fluff used in the special invention, which is mainly composed of pulp fibers and contains 10 to 60% by weight of a water-absorbing substance that swells and forms a gel when it comes into contact with a large amount of water. Layer 2 is typically a so-called pulp fluff in which pulp fibers obtained by crushing a sheet of wood pulp are deposited.

Further, a fluff-like stack of short fibers such as cotton linters or a bulk-like fiber stack made of hydrophobic synthetic resin can also be used.

The weight of this layer is 4 times the amount used in conventional water absorbent materials.
/2 or so, and is selected within the range of approximately 150 to 300 g/m''.

That is, in the case of a diaper in which the area of the absorbent layer 50 is about 2 Frrr1 x 55 m, it is preferable to use 20 to 40 g, especially 25 to 35 g of short fiber fluff.

The first layer 3 of tissue paper that is superimposed on the flan 7 layer 2 is
It is a thin paper with a basis weight of about 25 g/ra'', and more preferably crete tissue paper.

Also preferred is crepe tissue paper that has been treated to be water repellent.

Only one sheet can serve the purpose, but two or more sheets may be used in stacks.

The water absorbent sheet layer 4 is mainly composed of bulk fibers as described above, and contains 1
The sheet comprises 0 to 60% by weight of gel-forming water-absorbing material.

As a gel-forming water-absorbing substance that swells and forms a gel when it comes into contact with a large amount of water, it is possible to use natural products such as starch or mannose gelatin, but starch-polyacrylonitrile Salts of graft copolymers, alkali metal salts of alginic acid, cellulose derivatives such as carboxyalkylcellulose nonodium salts, calcium salts, ammonium salts, cellulose halide, etc.
Examples include polyoxymethylene sorbitol, polysankalide gum, and water-swellable polymers such as polyacrylamide and styrene-maleic anhydride copolymer glycol ester.

These substances can be used in the form of powder, flakes, or fine fibers, and those that can be obtained in the form of pulp, such as carboxymethyl cellulose or oxidized cellulose, are also suitable.

The water-absorbing sheet layer 4 can be manufactured by crushing a wooden valve seat, mixing it with particles of the gel-forming water-absorbing substance as described above, depositing this mixture on a screen belt, and then compressing it.

It has been found that if the material is sprayed with water during deposition and compacted using a calender, especially an embossing calender, a high-strength sheet can be obtained that is convenient for handling and processing.

Alternatively, after applying a water-absorbing substance solution to sheet pulp, it may be dried and crushed to obtain pulp fibers to which a water-absorbing substance is attached, and the pulp fibers may be aggregated and bonded to form a sheet.

The water-absorbing substance is used in an amount of 4010 to 60% by weight in the water-absorbing sheet layer.

The remaining components of the water-absorbing sheet layer 4 may be made entirely of Pal 7M fibers, or may also contain small amounts of binders, deodorizers, bactericidal agents, etc.

This sheet layer 4 has an apparent density of 0.05 to 0.25 g/
Since it is compressed to about 0.1 to 0.2 g/cril, it is compact and has excellent water absorption power.
Moreover, it exhibits a pleasant character and does not seem stiff.

In the present invention, each of the above layers includes a short fiber fluff layer 2,
A tissue paper layer 3 and a water absorbent sheet layer 4 are stacked in this order to form an absorbent layer unit 5.

Therefore, in the water absorbent material 1 of the present invention, the single absorbent layer unit 5 constructed in this way is coated with a suitable surface material 6,
For example, it can be made by wrapping it with non-woven fabric (
Figure 1).

In the water-absorbing material of the present invention configured in this way, the material 1
Liquid supplied to the surface, such as urine, passes through the surface material 6 and enters the fluff layer 2 without being separated, and then passes through the tissue paper layer 3.
The uke is passed on.

Since the fluff layer 2 is a spot-absorbing layer, the liquid is not diffused into the surroundings and remains relatively dry for the most part.

This effect is even more pronounced when a hydrophobic material such as synthetic pulp is used for this layer, which is a good thing.

Furthermore, as mentioned above, since the fluff layer 2 is relatively thin, most of the liquid passes through it and is transferred to the tissue paper layer 3.

However, this layer 3 made of one or several sheets of tissue paper itself has almost no water absorbing power, and the liquid passes through it and is separated from the relatively dense water absorbing sheet layer 4. It will be rapidly diffused to the surroundings in the interlayer gap.

The water-absorbing sheet layer 4 has a weight of 0.05 to 0.25 g//, especially 0.
This is because it has an apparent density of about 1 to 0.2 g,/.

For example, if you put tissue paper on top of a fluffy material like absorbent cotton and drop water from above, the water will not spread to the surrounding area, but if you spread tissue paper on top of cardboard and drip water on it, it will not get wet. It's the same logic that causes it to spread to its surroundings.

If crepe tissue is used, the diffusion will be even faster, and waterproof crepe tissue paper is even more preferable.

In this way, the liquid is brought to the water-absorbing sheet layer 4 in a state of being diffused over a wide area, which is then absorbed and evenly supplied to the surface of the gel-forming water-absorbing material, so that the water-absorbing material swells and forms a gel, containing a large amount of liquid in the gel structure.

The liquid thus trapped within the gel structure will not be released even when squeezed.

While FIG. 1 illustrates the simplest form of the invention, further configurations are shown in FIGS. 2 and 3.

Figure 2 shows a structure suitable for use in diapers,
Another layer 3' of tissue paper is applied to the surface of the absorbent layer unit 50 in which the short fiber fluff layer 2, the tissue paper layer 3, and the water-absorbent sheet layer 4 are stacked in this order, and the water-absorbent sheet layer 4 has a water-absorbing property. It is characterized in that it is not inserted over the entire thickness of the material 1, but is used only in the center.

6 is a surface material made of a unidirectional nonwoven fabric, and 7 is a waterproof paper or polyethylene film, etc., which is used to prevent liquid leakage in case of an emergency.

The short fibers of the additional tissue paper 3' rough tuff layer 2 act to prevent so-called cotton from coming out from the surface material 6,
It hardly contributes to the diffusion of liquid.

Especially in the case of diapers, the liquid is concentrated near the center,
Since both ends are used for covering the body rather than absorbing water, it is sufficient that the water-absorbing sheet layer 4 is used only near the center.

The case shown in Fig. 3 has a structure suitable as a sanitary napkin, and contains two absorbent layer units 5 that share a water absorbent sheet layer 4, and can be used by applying either to the body without distinguishing between the front and back sides. It is configured so that it can be done.

3' also indicates a tissue paper, which is used as a cover to prevent cotton lint as described above.

6 is a surface material.

Since the water-absorbing material of the present invention is constructed as described above, it is compact and has high water-absorbing properties.

This is due to the fact that a gel-forming water-absorbing substance is used in the water-absorbing sheet layer, and the liquid is diffused through the combination of constituent layers of the absorbent layer unit, thereby increasing the utilization of this water-absorbing substance.

Furthermore, since it uses a gel-forming water-absorbing material that absorbs water impulsively, and 7 layers of spot-absorbing furan are used on the side that comes into contact with the body, the surface side is always kept relatively dry. It has a soft texture and is soft to the touch.

Accordingly, the present invention provides a water-absorbing material suitable for frequent use in diapers, sanitary napkins, and the like.

[Brief explanation of drawings]

1 to 3 are diagrams schematically illustrating the cross-sectional structure of the water-absorbing material of the present invention. DESCRIPTION OF SYMBOLS 1...Water absorbent material, 2...7 short fiber layers, 3゜3'...one layer of tissue paper, 4...water absorbent sheet layer, 5...absorbent layer unit, 6...・Surface material, 7...
Waterproof layer.

Claims (1)

[Scope of utility model registration request] In water absorbent materials such as diapers or sanitary napkins,
This material has an absorbent layer unit in which seven layers of short fiber flan, one layer of tissue paper, and a water-absorbing sheet layer are stacked in this order, and the water-absorbing sheet layer is mainly made of pulp fibers and is resistant to a large amount of water. A water-absorbing material containing 10 to 60% by weight of a water-absorbing substance that swells to form a gel when contacted, and having an apparent density of 0.05 to 0.25 g/crl. .