JP2002035036A - Absorber and absorptive article using the same, and method for manufacturing absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an absorber which keeps absorption performance and softness while reducing its thickness. SOLUTION: Many through-holes 2a, 2a, etc., which penetrate to its rear surface are formed on one surface of the absorber. Many recessed holes 2b, 2b, etc., which do not penetrate to the rear surface and have a depth of >=30% the thickness of the absorber are otherwise formed on one surface of the absorber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an absorbent used for disposable diapers, sanitary napkins, incontinence pads, medical pads, and the like. TECHNICAL FIELD The present invention relates to an absorbent body that fits a human body and has excellent wearability, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Since bodily fluid absorbent articles such as disposable disposable diapers, sanitary napkins and incontinence pads have been introduced to the market,
Various improvements have been accumulated for absorbers using superabsorbent resins.

[0003] As is well known, a superabsorbent resin has properties such as water absorption and swelling when it comes into contact with water to form a gel, and once it absorbs water, it does not separate even if some pressure is applied.
Its water absorption reaches tens to thousands of times its own volume, and shows a tremendous water absorption. Although the superabsorbent resin alone exhibits the above-mentioned water-absorbing power alone, it cannot exhibit water-absorbing power unless it is in a wet state to some extent, and has a low water-absorbing speed. It is mixed in the form of powder, crushed powder or pellets.

In recent years, in the case of this type of absorbent article, there are problems such as inconvenience in carrying due to bulkiness or poor storage properties. Thinning and compactness have been achieved. Even if the absorber is made thinner or more compact, the amount of water absorption cannot be reduced, so it is usually dealt with by increasing the content of the superabsorbent resin. So-called "gel blocking", in which voids between swollen water-absorbing polymer particles are extremely reduced.
Occurs, and a desired water absorbing power cannot be exhibited. As a result, the phenomenon that the penetration of urine is inhibited by the bond between the water-absorbing polymer particles and the urine whose penetration has been inhibited returns again and flows out is seen.

Although various methods for suppressing the gel blocking have been proposed, at present, the content ratio of the superabsorbent resin to the total weight of the superabsorbent resin and the superabsorbent resin such as pulverized pulp is preferably within 80%, and more preferably less than 80%. In many cases, the thickness is reduced to less than 50% and the absorber is subjected to severe pressing to reduce the thickness.

[0006] In addition, as the content of the superabsorbent resin is increased and the fiber component is relatively decreased, there is a problem that the absorber becomes liable to be twisted or cracked. For example, a method has been proposed in which cellulose of pulp is cross-linked with an appropriate cross-linking agent, a binder resin is added, or heat-fusible fibers are mixed and fibers are adhered to each other by heat treatment.

[0007]

However, in the case where the absorber is thinned by press working, the absorbent (such as crushed pulp) has an extremely high product density, so that the water absorption capacity is reduced and the absorption is reduced. The body becomes stiff and the wearer feels stiff. Further, there is a problem that wrinkles are formed to be large and leakage easily occurs.

In the case of the above-mentioned method for coping with cracks or the like of the absorbent, the cross-linking treatment or the heat treatment causes the body fluid absorbing capacity of the fiber itself to decrease, or the swelling property of the superabsorbent resin is impaired. There were problems such as the occurrence of a problem, a decrease in the water absorbing ability due to the complete coverage of the superabsorbent resin with the binder, and an increase in the rigidity of the absorber due to the binder or heat fusion, which impairs the feeling of wearing.

On the other hand, in order to compensate for the reduced water absorption performance or to make the absorbent body fit to the body, a fitting emboss is formed, but the characteristics of the absorbent body itself are not improved. It is not a fundamental solution.

Accordingly, a main object of the present invention is to provide an absorbent body which can maintain absorption performance while achieving a reduction in thickness and has sufficient flexibility.

[0011]

According to a first aspect of the present invention, there is provided an absorbent body having a plurality of through-holes penetrating a back surface of the absorbent body.

[0012] The absorber according to the second invention is characterized in that a number of hollows are formed in the surface of the absorber without penetrating the back surface and having a depth of 30% or more of the thickness of the absorber. is there.

[0013] In these cases, the through-holes or hollows are formed at a rate of 0.1 or more per cm ² ,
The hole area is desirably 0.03 mm ² or more on the absorber surface. When the dispersion density of the through-holes or depressions is less than 0.1 per 1 cm ² or the hole area is less than 0.03 mm ² on the absorber surface, the absorbent of the present invention has the desired absorption and Lack of flexibility. Regarding the degree of flexibility, the value obtained by the stiffness test described later is 15 mm
It is desirable to determine the hole formation density and the hole area so as to be within.

In order to reduce the thickness of the absorber, the absorbent is made of pulp and a superabsorbent resin, and the ratio of the superabsorbent resin to the total weight of the pulp and the superabsorbent resin is at least 40% by weight, preferably 50%. % By weight or more, and pulp produced by a drum-laying method or an air-laid method is preferable.

The absorber is produced as an absorbent article interposed between a liquid-permeable top sheet and a liquid-impermeable back sheet.

In the present invention, absorptivity and flexibility are imparted by simply forming a large number of through holes or non-through holes in the absorber. That is,
Regarding the absorbency, the surface area of the absorber is increased by the hole processing, and the absorption rate and the body fluid diffusion performance are improved, so that the absorbability is improved. As for the flexibility, as will be clear from the experimental examples described later, much higher flexibility is provided as compared with an untreated absorber. Therefore, even if the thickness of the absorber is reduced by the press treatment, the absorber exhibits the same flexibility (within a stiffness evaluation of 15 mm or less) as the drum-laid fiber absorber, and has sufficient water absorbing performance. The body follows the movement of the body and prevents the leakage of body fluid. In addition, the user's feeling of wearing is closer to that of underwear, so that the user can wear comfortably without discomfort.

When the depth of the hollow is less than 30% of the thickness of the absorber, the absorber of the present invention cannot have the desired absorbency and flexibility. Therefore,
Embossing treatment such as diamond embossing which has been conventionally formed on the surface of the absorber for texture etc. is excluded from the present invention because it is at most within 20% of the thickness of the absorber.

On the other hand, the manufacturing method is such that a hole forming roll having a large number of projections on the roll surface and an anvil roll having a concave portion at a position corresponding to the projection are opposed to each other, and an absorber is passed between the two rolls. Accordingly, a large number of the through holes or the pits are formed in the absorber surface, and the thickness of the absorber is 25 to 100% of the thickness before the hole processing. The method of forming a hole using the hole forming roll and the anvil roll can be easily incorporated into an existing production line. The pressing of the absorber may be performed simultaneously with the hole processing, or may be performed in a step before the hole processing.

[0019]

Embodiments of the present invention will be described below in detail with reference to the drawings.

The absorbent is used as an absorbent element for disposable disposable diapers, sanitary napkins, incontinence pads, medical pads and the like. In many cases, the absorbent is made of a water-absorbing material such as pulp and the like. And a superabsorbent resin mixed in a form such as a pellet. In some cases, a medical pad or the like may be made of a single water-absorbing material without using a highly water-absorbing resin.

In absorbent articles such as disposable disposable diapers, sanitary napkins, incontinence pads, etc., the absorbent is commercialized between a liquid-impermeable back sheet and a liquid-permeable top sheet. The liquid-impervious back sheet is, for example, a liquid-impervious sheet made of a polyethylene sheet or the like, a water-permeable / moisture-permeable sheet having moisture permeability from the viewpoint of preventing stuffiness, and a composite sheet of a nonwoven fabric and a waterproof sheet. On the other hand, as the liquid permeable surface sheet, a perforated or non-porous nonwoven fabric or a porous plastic sheet is suitably used. The material fibers constituting the nonwoven fabric can be synthetic fibers such as olefins such as polyethylene or polypropylene, polyesters, polyamides, etc., recycled fibers such as rayon and cupra, and natural fibers such as cotton. A nonwoven fabric obtained by an appropriate processing method such as a method, a spun bond method, a thermal bond method, a melt blown method, and a needle punch method can be used.

Examples of the pulp include cellulose fibers such as chemical pulp and dissolved pulp obtained from wood, and artificial cellulose fibers such as rayon and acetate. Softwood pulp having a longer fiber length than hardwood pulp is used. Are preferably used in terms of function and price. Further, as the production method, a method produced by a drum stacking method or an air laid method is preferable.

In order to satisfy the absorption performance and flexibility while reducing the thickness of the absorber, as shown in FIGS. …. This hole processing may be a through hole 2a penetrating to the back surface as shown in FIG. 3 (A), or a non-penetrating hollow hole 2b as shown in FIG. 3 (B). Is also good. The depth of the hollow 2b is at least 30%, preferably at least 50%, more preferably at least 70% with respect to the thickness of the absorber 1. By making the hollows 30% or more with respect to the thickness of the absorber 1, the embossing process such as the diamond embossing can be differentiated from the conventional embossing process. become. The hole shape is preferably a circular shape, but may be a polygonal shape such as a star shape, a triangular shape, or a square shape.

In practice, clear through-holes 2a or hollows 2b are often not formed due to the restoring force of the pulp fiber. However, as shown in an experimental example described later, such holes 2 are formed. As a result, flexibility is clearly developed. The hole processing is performed at a rate of 0.1 or more per 1 cm ² , and the hole area is desirably 0.03 mm ² or more on the absorber surface. As a measure of the flexibility, it is desirable to determine the hole formation density and the hole area so that the value obtained by the rigidity test is within 15 mm.

In the stiffness test, as shown in FIG.
Absorbent specimen 20 having a width and a height of 100 mm × 100 mm was folded so as to have a width of 50 mm, and the edge was fixed to the reference line L.
An acrylic plate 21 having a size of 0 mm × 150 mm and weighing 60 g was brought in, and the central portion was fixed to the reference line L. This is a test method in which the height H of the side (side) is measured, and a value obtained by subtracting the bulk (thickness t × 2) of the absorber from the height H is used as a stiffness index.

As shown in FIG. 4, a large number of protrusions 4 are formed on the roll surface to perform the hole processing on the absorber.
, and an anvil roll 5 having recesses 5a, 5a,... at positions corresponding to the protrusions 4a so as to allow the absorber 1 to pass between the rolls 4,5. I do. As shown in FIG. 5, the protrusion 4a fits into the recess 5a in the passage portion of the absorber 1, and the absorber 1 is formed with a through hole 2a penetrating to the back surface or a non-through hole 2b. As the shape of the protrusion 4a, a needle-like (needle) or conical protrusion is suitably adopted.

[0027]

[Experimental example] A hole-forming roll prepared by forming a large number of needle-shaped protrusions (needle) having a base end diameter of 2 mmφ and a length of 3 mm on the surface at a dispersion density of 6.25 / cm ² was prepared. 500
on pulp absorbers ^{g / m 2, 350g / m} 2, subjected to needle hole processing, to measure the stiffness. For comparison, the stiffness of an absorber (untreated) having a similar basis weight and the stiffness of a case where diamond embossing is applied to the absorber surface by an embossing roll having diamond embossed on the surface are also shown. In addition, the test was performed for each of the stiffness in the line direction and the stiffness in the direction perpendicular to the line in order to check the anisotropy. Table 1 shows the results. In addition, in order to make the comparison conditions the same in all of the needle hole treatment, the non-treatment, and the diamond embossing treatment, the press ratio was set to 50% in thickness.

[0028]

[Table 1]

As is clear from Table 1, in the case of the present absorbent body which has been subjected to the needle hole treatment according to the present invention, the rigidity is remarkably reduced as compared with the rigidity of the untreated absorbent or the diamond embossed absorbent. It turns out that flexibility is provided. This tendency becomes more remarkable as the basis weight of the absorber increases.

[0030]

As described above in detail, according to the present invention, it is possible to obtain an absorbent body which can maintain absorption performance and achieve sufficient flexibility while achieving a reduction in thickness.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing the present absorber 1. FIG.

FIG. 2 is a plan view thereof.

FIG. 3 (A) shows a mode of forming a through hole 2a, and FIG.
It is a principal part expanded sectional view which shows the form of b.

FIG. 4 is a schematic view showing a hole drilling process of the present absorber.

FIG. 5 is an enlarged sectional view of a main part of a hole processing section.

FIG. 6 is a test procedure diagram for evaluating the rigidity of the absorber.

[Description of Signs] 1 ... absorber, 2 ... drilling, 2a ... through hole, 2b ... hollow hole

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) A61F 13/18 360 (72) Inventor Ikuo Tachibana 15-21 Minamibeppu-cho, Settsu-shi, Osaka Zumikonai Co., Ltd. (72) Inventor Keiji Torigoe 4765-11 Samukawa-cho, Iyo-Mishima-shi, Ehime F-term in Bio Paper Converting Co., Ltd.

Claims (9)

[Claims] 1. An absorber comprising a plurality of through holes formed in the surface of the absorber and penetrating the back surface. 2. An absorber, wherein a number of hollows having a depth of not less than 30% of the thickness of the absorber are formed in the absorber surface without penetrating the back surface. 3. The absorber according to claim 1, wherein said through holes or hollows are formed at a rate of 0.1 or more per cm ² . 4. The absorber according to claim 1, wherein the area of the through hole or the hollow is 0.03 mm ² or more on the surface of the absorber. 5. The absorbent according to claim 1, wherein a value obtained by a stiffness test is 15%.
The absorber according to any one of claims 1 to 4, which has a size of not more than mm. 6. The absorbent according to claim 1, wherein the absorbent comprises pulp and a superabsorbent resin, and a ratio of the superabsorbent resin to the total weight of the pulp and the superabsorbent resin is 40% by weight or more.
5. The absorber according to any one of 5. 7. The absorbent body according to claim 6, wherein said pulp is produced by a drum-laying method or an air-laid method. 8. An absorbent article comprising the absorbent body according to claim 1 interposed between a liquid-permeable top sheet and a liquid-impermeable back sheet. 9. An absorber roll having a large number of projections on the roll surface and an anvil roll having a recess at a position corresponding to the projections are opposed to each other, and an absorber is passed between the two rolls. The through-hole or the recessed hole is formed, and the thickness of the absorber is 25 to 100% of the thickness before the hole processing.
8. The method for producing an absorber according to any one of items 1 to 7.