JPS6373956A - Absorbable article - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to absorbent articles, and more specifically, to sanitary napkins, disposable diapers, pads for incontinence, breast pads, spring pads, surgical pads. The present invention relates to an absorbent article that can be suitably used for medical supplies such as, etc., or other applications that require liquid absorption and retention.

[Conventional technology and problems]

In recent years, so-called water-absorbing polymers (water-insoluble absorbent resins) that absorb tens to hundreds of times their own weight in water have been developed, and are used in sanitary products such as sanitary napkins and disposable diapers, as well as in the agriculture, forestry, and civil engineering fields. It is used as water-retaining and water-absorbing materials.

The water-absorbing polymers used are generally in the form of granules, and because of their granular form, in most cases they are actually used by sand-inching with paper or by mixing them into pulp for embossing. It is used by converting it into sheet-like, film-like, etc. shapes by applying pressure-bonding processes such as those described above, or compounding processes such as melt-sealing using thermoplastic resins. However, even with these composite methods, the polymer cannot be avoided from falling off. Composite synthesis by melt sealing, which causes relatively little polymer to fall off, coats the polymer with thermoplastic resin, which prevents contact with liquids such as water.
Therefore, there is a drawback that absorption performance is significantly reduced.

In order to improve these drawbacks, many proposals have been made for absorbent articles in which the polymer does not fall off, and products in the form of films, fibers, etc. have been proposed.

In film form, the surface area is small and the absorption rate is inferior, and since it exists as a surface, it restricts the flexibility of the absorbent article. On the other hand, even if fibrous materials have satisfactory flexibility, they have the disadvantage of low gel strength when swollen, and it cannot be said that absorbent articles with good absorption performance and no polymer shedding are necessarily obtained.

Furthermore, a method has been proposed in which a water-soluble monomer that can be converted into a water-absorbing polymer, such as (meth)acrylic acid or its salt, is applied to a fibrous base and then polymerized, but in these cases, the polymer may fall off. However, when the fibrous base is hydrophilic, the monomer aqueous solution easily penetrates into the base, and in such absorbent articles, the capillary diameter between the fibers is reduced, and the absorption performance is reduced. , the absorption rate is particularly poor. In addition, even if it is applied to the base surface without penetrating into the interior, because of its hydrophilic fibers, it spreads and adheres to the surface, tends to polymerize and form a planar form, and as a result, when the polymer swells with liquid, , an occlusive film is formed on the fiber surface, which prevents liquid from permeating into the absorbent article, resulting in poor absorbent properties. In addition, when the base is hydrophobic, the monomer aqueous solution does not wet and spread, so it does not have the disadvantages seen with wood-loving bases, but because it is hydrophobic, the absorbed liquid can be absorbed inside the base. It is difficult to utilize the polymer effectively because of its poor diffusivity and poor contact efficiency between the polymer and the liquid.

Therefore, it is desired to develop an absorbent article that has excellent absorbent properties without shedding of the polymer and has a high contact efficiency (diffusion effect) between the polymer and the liquid as soon as possible.

[Means for solving problems]

The present inventors have developed a method that has excellent absorbency and no shedding of the polymer.
As a result of intensive study to obtain an absorbent article with excellent diffusibility and high contact efficiency between polymer and liquid, at least a portion of the fiber length was embedded in a water-insoluble absorbent resin and a cough water-insoluble absorbent resin. Mixing or laminating a composite absorbent material made of fibers, at least a portion of which is a water-insoluble absorbent resin with fibers protruding from the fibers, and a cotton-like or sheet-like material made of cellulose fibers. It was discovered that by doing so, the performance of the polymer can be fully exhibited, and an absorbent article with extremely excellent diffusivity without shedding of the polymer can be obtained, and the present invention has been completed.

That is, the present invention comprises a water-insoluble absorbent resin and fibers in which at least a portion of the fiber length is embedded in the water-insoluble absorbent resin, and at least a portion of the fibers is made from the water-insoluble absorbent resin. The present invention relates to an absorbent article characterized by comprising a composite absorbent material having a shape in which fibers are exposed outside, and cellulose fibers.

In the present invention, a water-insoluble absorbent resin and fibers having at least a part of the fiber length embedded in the water-insoluble absorbent resin are used. A composite absorbent material having a shape in which the fibers are exposed is, as shown in FIG.
At least some of the fibers 2 have a shape in which the fibers grow out from the surface of the water-insoluble absorbent resin 1 like whiskers.

The fibers here may be either hydrophilic fibers such as bulb or rayon, or hydrophobic fibers such as polyester, polyethylene/polypropylene composite fibers, or polypropylene. It is possible to obtain a composite absorbent material that has excellent water-filling effects, very good wettability with liquid, and good liquid transport between composite absorbent materials.

In addition, when heat-fusible fibers are used as hydrophobic fibers,
It is possible to bond fibers through composite absorbent material,
A product with excellent shape retention can be obtained. It is also possible to mix both hydrophilic and hydrophobic fibers, thereby making it possible to obtain a fiber having both of the above properties.

The fibers used here preferably have a fiber length of 1 mm or more, and as a composite absorbent material, having whiskers of 1 mm or more allows it to be easily entangled with other fibers. The ratio of the water-insoluble absorbent resin to the fibers is preferably 5% to 75% by weight of the absorbent resin, more preferably 50% or less, which is as close to the specific gravity of a single fiber as possible. However, if the amount of absorbent resin is reduced too much, sufficient liquid retention cannot be obtained, so 25% to 50% is most desirable.

Examples of the water-insoluble absorbent resin in the present invention include crosslinked polyacrylates and acrylic acid-acrylic acid ester copolymers, self-crosslinked polyacrylates, hydrolysates of starch acrylonitrile graft polymers, and cellulose-acrylonitrile Graft polymer hydrolyzate, crosslinked polyacrylamide and its hydrolyzate, crosslinked sulfonated polystyrene, crosslinked poval, crosslinked vinyl ester-unsaturated carboxylic acid copolymer saponified product, crosslinked isobutylene- Maleic anhydride copolymers, crosslinked polyethylene oxide, copolymers of acrylates and ammonium salts of dialkylaminoethyl methacrylate, and the like are preferably used.

In the present invention, the method for obtaining a composite absorbent material of a water-insoluble absorbent resin and fibers includes, for example, (1) mixing the water-insoluble absorbent resin that has swollen by absorbing water and fibers using a Ni-Goo, mortar mixer, or all-purpose mixing; (2) A water-soluble ethylenically unsaturated monomer (for example, (meth)acrylic acid or its salt) that is converted into a water-insoluble absorbent resin. , vinyl sulfonic acid or its salts, vinyl phosphonic acid or its salts, etc.) and fibers are kneaded by the above method, polymerized, dried, and pulverized; (3) water-soluble ethylene that can be converted into water-insoluble absorbent resin; Examples include a method of impregnating fibers in an aqueous solution of a sexually unsaturated monomer, adhering the monomer to the fibers, and then polymerizing, drying, and pulverizing the fibers, but the method is not limited to the above methods.

The above-mentioned composite absorbent material of water-insoluble absorbent resin and fibers cannot serve as a sufficient absorbent material by itself, and can only exhibit its original function when combined with other fibrous or sheet-like materials.

That is, by incorporating the above composite absorbent material into a capillary structure formed by a fiber aggregate, it can have the liquid retaining space, liquid diffusivity, and shape retention ability of the fiber aggregate.

The composite absorbent material has a specific gravity close to that of the fibers, and has whiskers that can freely intertwine with the fibers, so it can freely intertwine with the fibers. That is, it becomes possible to uniformly arrange the composite absorbent material everywhere in the fiber assembly.

The fibers to be mixed with the composite absorbent material are preferably those that are easily entangled with the composite absorbent material and have the ability to absorb, diffuse, and retain liquid. Specifically, cellulose-based hydrophilic fibers such as bulb, rayon, and cotton are preferred. can be mentioned. These have extremely high hydrophilicity, so they have a strong ability to draw liquid into the fiber aggregate, and because they wet and spread easily, they have the ability to quickly diffuse liquid inside, and their strong capillary force holds liquid firmly. I can do things.

In other words, these fibers absorb liquid and diffuse it, thereby transporting the liquid to the composite absorbent material placed inside the fiber aggregate, and until the composite absorbent material absorbs the liquid. It functions to hold the liquid for a while.

The composite absorbent material and the above-mentioned cellulose fibers can be combined in two ways: (1) uniformly mixing the cotton-like or staple-like cellulose fibers 4 and the composite absorbent material 3 as shown in Figure 2 (al); 2) It is possible to stack the sheet-like cellulose-based fiber aggregate 5 and the composite absorbent material 3 in layers as shown in Figure 2 (bl), and as shown in Figure 2 (C).
, (dl), it is also possible to combine the above (1) and (2).

In the present invention, it is possible to freely change the ratio of cellulose fibers and composite absorbent material, so several hundred ml of disposable diapers etc.
When used as an absorptive material to absorb liquid, it is preferable to use a material with a high amount of composite absorbent material and a high overall saturated absorption capacity, since the amount of liquid to be absorbed is large. As an absorber, the amount of composite absorbent material is 1 in weight ratio.
0 to 80% is preferably used.

[Action and effect]

The product of the present invention has a water-insoluble absorbent resin retention performance of 100% due to the characteristics of the hydrophilic capillary structure created by the cellulose fiber aggregate.
%, it has excellent liquid diffusivity, greatly improves the effective utilization rate of absorbent resin, and has very excellent liquid retention.

In the product of the present invention, the absorbent resin does not fall off and the absorbent resin can be freely placed in any position of the cellulose fiber aggregate, so the time required for the absorbent resin to come into contact with the liquid can be controlled. Therefore, it is possible to change the liquid retention characteristics as necessary.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example-1 50 g of a cross-linked sodium polyacrylate that has swollen by absorbing equal weight of water and 75 g of bulbs are kneaded using a screw kneader, dried, and further crushed using a rotary vane type crusher to form a polymer. A composite absorbent fil with a bulb weight ratio of 25/75 was obtained.

Similarly, the weight ratio of the valve was changed, and the weight ratio was 501.
50 composite absorbent (2), 75/25 composite absorbent (3)
) was obtained.

Composite absorbent materials (4) to (7) were also obtained using rayon, polyester, polyethylene/polypropylene composite fiber, or hydrophilic polyester instead of the bulb.

In addition, instead of the sodium polyacrylate crosslinked product, a 1:1 copolymer crosslinked product of sodium polyacrylate-dimethylaminoethyl methacrylate quaternary ammonium salt was used and mixed with the valve in the same manner, resulting in a composite absorbent material (8).
I got it.

Their absorption performance is shown in Table 1.

Example 2 A certain amount of the composite absorbent obtained in Example 1 was added to flocculent pulp and mixed to obtain a homogeneous composite absorbent/pulp mixture. This was stacked on absorbent paper so that the basis weight was 180 g/m, and then compressed so that the density was 0.08 g/cffl to obtain a product of the present invention.

Samples were prepared with various composite absorbent/bulb mixing ratios, and their absorbency was measured. The results are shown in Table-2.

A sample with a size of 100 mm x 100 mm was used.

Table 2 Note) 1) Time required to absorb simulated blood Log 2) After absorbing 10 g of simulated blood, leave it for 3 minutes, then
Amount of liquid released when a pressure of 0 g/- is applied Example 3 The structure of the laminate consisting of the composite absorbent material and the cellulose fiber aggregate was varied as shown in Table 3, and the absorption performance was evaluated as described above. Measurements were carried out in the same manner.

The results are shown in Table-3.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of the composite absorbent material according to the present invention, and FIG. 2 is a cross-sectional view showing various examples of the absorbent article of the present invention. 1... Water-insoluble absorbent resin 2... Fiber partially embedded in water-insoluble absorbent resin 3... Composite absorbent material

Claims (1)

[Claims] 1. Consisting of a water-insoluble absorbent resin and fibers with at least a portion of their fiber length embedded in the water-insoluble absorbent resin, at least a portion of the fibers protrude from the water-insoluble absorbent resin. An absorbent article characterized by comprising a composite absorbent material having a shape similar to that of a cellulose fiber.