JPS5926467B2 - Manufacturing method of water absorbing composite member - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to the production of a water-absorbing composite member in which water-absorbing powder (water-absorbing agent) having a high water-absorbing property is fixed to a fiber-based facepiece without impairing its performance. Regarding the method.

In recent years, various hydrogels have been created that can absorb large amounts of water and swell, thereby retaining water within tissues.

(Special Publication No. 49-43395, No. 50-135196
(Japanese Unexamined Patent Publication No. 51-125468) Generally, these substances are in the form of powder, fiber, or sheet, and when they absorb water, they become jelly-like or glue-like and have the effect of reducing the fluidity of water. However, the strength is significantly reduced, making it difficult to maintain its shape against external stress.

In particular, when it is in powder form, the water absorbent is used in effective applications, such as absorbent materials that absorb and fix body fluids such as disposable diapers and sanitary napkins. Difficult to stick to target and fixed position.

In addition, in the case of a film, the fibrous material temporarily retains water in the interlocking voids of the fibers, which apparently absorbs water quickly, but since it is a continuous facet, the surface area is small and the apparent water absorption rate is slow. Furthermore, in the case of fibers, they have relatively good water absorption properties and have a desirable shape, but if the fibers are individually intertwined to form a sheet, the entanglement will unravel when water is absorbed, and it will not be able to withstand external stress. On the other hand, it is similar to other shapes in that it flows easily. Therefore, when these water absorbents are used as one component of an absorbent member, they must be able to retain their outer shape in some way even after absorbing water, have voids to temporarily retain water, and be used as a composite material as an absorbent member. It is effective to use a combination with a base material, which is easier to handle than the single unit itself against moisture when exposed to moisture.

The present invention satisfies these requirements by selecting a fiber-based face piece such as paper or woven fabric as the base material after conducting a study.
When combining with a water-absorbing powder, at least a part of the surface of the water-absorbing powder particles is swollen by absorbing water, and is made into a paste-like form, thereby imparting adhesive properties; It was discovered that a method of fixing the powder onto the fiber-based face piece while maintaining the powder form was effective, and the work was completed based on this knowledge.

Generally, when combining other substances for the purpose of imparting other properties to the facepiece, the substances to be combined are dissolved in an appropriate solvent or suspended in a dispersion medium, applied to the facepiece, and then There are methods such as removing the solvent and drying it, or if the materials to be combined have a melting point, applying them in a molten state and then cooling them, or sprinkling powder on the face piece and then performing caloric welding. It will be done.

In the case of the water absorbent according to the present invention, the above-mentioned hardening method is inappropriate.

That is, when water is chosen as the dispersion medium for a water absorbent, this dispersion...as expected from hydrogel formation, does not flow unless it is considerably diluted, and at some stage becomes rubber-like, then jelly-like, or pasty-like. It is difficult to coat due to its extremely high viscosity, and if the concentration is low to facilitate coating, a large amount of heat energy will be required in the subsequent drying process, or an extremely long drying time will be required. Furthermore, the resulting coating forms a continuous film, which reduces the surface area and reduces the rate of water absorption. Further, the water absorbent used in the present invention does not have a clear melting point and is easily decomposed by heating, so it cannot be applied by melting. However, in the method of the present invention, when attaching the water-absorbing powder to the fiber-based facepiece, at least a portion of the surface of the water-absorbing powder particles is swollen by allowing a very small amount of water to exist in the system. It is characterized in that it is made into a paste-like form and has adhesive properties so that it can be fixed onto the fiber base face piece.

By employing the method of the present invention, it is possible to easily obtain a water-absorbing composite member in which the water-absorbing powder is uniformly applied on the fiber base material face piece, and the composite member thus obtained can absorb water. It has great effects of high speed and water absorption.

The amount of water used in the present invention varies depending on the water absorption capacity of the water absorbent, but the amount is just enough to swell a small part of the surface of the powder particles.On the other hand, if a large amount of water is used, the water will This is not preferable because it penetrates into the interior of the powder, causing the powder to collapse and deform, forming a film that is continuously connected to adjacent fibers or water absorbents.

The required amount of water can be determined by a simple preliminary experiment.
As in the present invention, if the water-absorbing powder is swollen with a small amount of water to impart adhesive properties and applied to the fiber-based facepiece, thermal energy can be saved in the subsequent drying process, and the drying speed can be accelerated. It also has the effect of not impairing the so-called texture of the fiber base material.

As a specific implementation method for achieving the purpose of the present invention, for example, water-absorbing powder is sprinkled on a fiber-based face piece that has been pre-impregnated with a necessary amount of water, and the powder is applied to the fiber-based face piece. Examples include a method of absorbing water when it reaches the top and fixing it through the process described above, and a method of spraying a mist of water when scattering powder onto a dry fiber-based face piece. Not restricted. After adhering the water-absorbing powder to the fiber-based facepiece, the drying process begins, but before that, one more facepiece is placed and crimped to create a sandwich structure, or a surface that is difficult to adhere to, such as release paper. It may be covered with a sheet and crimped, or it may be dried without being crimped.

A preferred embodiment is a method of embedding the water-absorbing powder in the gaps between the fibers by pressing.1 Furthermore, by pressing in an uneven manner during the pressing, water is temporarily retained in the concave portions. It allows for play and is more effective.

The fiber-based face piece used in the present invention is selected from paper or non-woven fabric that can maintain its shape even when absorbed with water, but it is more preferable to use paper or non-woven fabric that can retain its shape even when it absorbs water. A paper-like material with voids is desirable.

In addition, the water absorbent used in the present invention has high water absorption performance and has the property of being difficult to release retained water due to external stress. Polymer electrolyte obtained by decomposition (Japanese Patent Publication No. 4943395, Japanese Patent Publication No. 50-135
196), starch copolymerized with a vinyl monomer having a water-affinity group (Japanese Patent Application Laid-Open No. 125468/1983) is particularly useful, and also polyacrylamide, polymethacrylamide, polyacrylic acid, and their metals. cross-linked gel-like products of water-soluble polymers including salts, polymethacrylic acid and its metal salts, polyvinylpyrrolidone, polyhydroxyalkyl acrylates and polyhydroxyalkyl methacrylates, methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, cyanoethylcellulose, etc. Any polymeric substance, such as a high molecular weight cellulose ether, which is insoluble in water but can swell in water and retain a large amount of water within its tissue can be used.

A composite member of a water absorbent powder and a fiber-based face piece produced by the method of the present invention can be usefully used as disposable soft products such as pillows, hospital bed pads, surgical pads and sheets, and sanitary products. Further examples of uses include stamps, labels, adhesive tapes, etc. Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 15y/M2 commercially available tissue. The paper was spread on a wire mesh and sprayed with 30-409/M2 water using a sprayer.

At this time, the tissue becomes dirty due to moisture absorption. The paper swelled by about 8% and was stretched, and then a predetermined amount of water absorbent powder was sprinkled onto the wet tissue paper. The water absorbent powder used was General Mills. Chemicals. SGP-502S manufactured by Incorporated (after graft copolymerizing acrylonitrile to Denfuso, water decomposition L with caustic potash)
1 carpoxypotassium salt, a polymer substance with carboxamide groups). (Method A) Transfer the water absorbent powder to a tissue. After spraying on the paper, the tissue was further moistened in the same manner. Paper was placed on it, crimped with a press, and air-dried.

(Method B) Transfer the water absorbent powder to the tissue. After being spread on the paper, the upper surface was covered with release paper, pressed with a press, and air-dried.

Comparative example 1 Teishu. The amount of water sprayed on the paper is 100120
The same method as in Example (Method A) was adopted except that f/M2 was increased.

Comparative Example 2 The same water absorbent as in Example was added to 150 times the amount of water and stirred well to form a putty.

Next, the nonwoven fabric was stretched on a wire mesh, a putty-like material was applied using a spatula, and water was evaporated and dried in a hot air dryer. Example,
The following measurements were performed on the water-absorbing composite members obtained in Comparative Examples 1 and 2.

The results obtained are summarized in Table 1. The results of the water absorbent powder itself (Comparative Example 3), which was used as a reference, are also listed. (1) Measurement of water absorption rate Place the water absorbing composite member 19 in a beaker, add 50 ml of ion-exchanged water, and wait until the composite member absorbs water and the water loses its fluidity. Measure the time it takes.

(2) Place 0.5 g of the water-absorbing composite member in a Buchna furnace lined with filter paper, add ion-exchanged water, and leave for 10 minutes.
Then, after suctioning at 60 degrees Hg for 10 minutes, the amount of water absorbed was measured. Note that the amount absorbed by filter paper is excluded. From the above results, it can be seen that the water absorption rate of the example of the present invention is faster than that of the water absorbent powder itself of Comparative Example 3.

This is particularly noticeable in method B. In addition, when the water absorbent is a continuous film as in Comparative Examples 1 and 2, the water absorption rate,
Both the amount of water absorption decreases.

Although not particularly shown in the table, the texture of the fiber base material is not preferable when the water absorbent is made into a continuous film as in Comparative Examples 1 and 2 because stiffness appears.

Claims (1)

[Claims] 1. When fixing the water-absorbing powder to the fiber-based face piece,
A method for manufacturing a water-absorbing composite member, characterized in that the powder is swollen with water in an amount that does not form a continuous film layer and fixed by imparting adhesive properties. 2. Claim 1, in which the water-absorbing powder is obtained by copolymerizing starch with acrylonitrile and then hydrolyzing it to form a polymer electrolyte, or by copolymerizing starch with a vinyl monomer having a water-affinity group. The method described in section. 3. A method for manufacturing a water-absorbing composite member, which comprises adhering water-absorbing powder to a fiber base material facepiece by the method described in claim 1, followed by pressing and drying. 4. A method for producing a water-absorbing composite member, which comprises fixing the water-absorbing powder to a fiber base material facepiece by the method described in claim 1, and then pressing the powder into an embossed shape and drying it.