JP3490477B2 - Absorbent articles - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an absorbent article such as a disposable diaper or a sanitary napkin having a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorbent body interposed therebetween. More specifically, the present invention relates to an absorbent article using an absorber having excellent absorption performance and strength.

[0002]

2. Description of the Related Art Generally,
Absorbent articles such as disposable diapers include a surface material made of a liquid permeable sheet such as a non-woven fabric, a back material made of a liquid impermeable sheet such as a polyolefin film, and hydrophilic fibers such as pulp fibers between these sheets. It is formed from an absorbent body formed by stacking fibers. In recent years, a technique for mixing a superabsorbent polymer such as a polyacrylate crosslinked product with an absorber for the purpose of improving the absorption performance has been shown, and there is a tendency to increase the amount of these superabsorbent polymers to be used.

However, in the absorbent body of the absorbent article, as shown in FIG. 5, when the content of the superabsorbent polymer 7 in the pulp fiber 6 increases, the superabsorbent polymer 7 may not be uniformly mixed during molding. . Further, the super absorbent polymer 7 spills from the lower layer of the absorber 4 and is scattered outside the product to cause so-called polymer leakage, which causes inconvenience in production. In addition, since the amount of pulp fibers in the absorber is relatively reduced, the absorption rate of the absorber may be reduced and the desired absorption performance may not be obtained, or the absorber may crack or lose its shape when wet. . As a result, the absorbent article deteriorates in performance and deteriorates the fit of the wearer.

From the above, polymer leakage can be prevented by increasing the diameter of the super absorbent polymer of the absorbent body, making it into a shape having a large friction with pulp fibers, or sandwiching it with a fine mesh liquid permeable sheet. It is possible to prevent it. However, it is not always good in terms of absorption performance and strength of the absorber. Further, in order to prevent breakage and shape collapse as much as possible, hot melt fibers are mixed and heat treated as a technique for improving the strength of the absorber, but there is a problem in terms of absorption performance (Japanese Patent Laid-Open No. 4-202895). JP-A-63-318941, JP-A-63-260555
(Japanese Patent Laid-Open No. 1-215575). Therefore, an object of the present invention is to provide an absorbent article which does not have damage or shape loss of the absorbent body and maintains an excellent body fluid absorbing ability and an excellent fitting property.

[0005]

The present invention provides an absorbent article having a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorbent body interposed therebetween, wherein the absorbent body is It is mainly composed of pulp fiber impregnated with water-soluble binder and super absorbent polymer .
The binder exerts a tack force on the pulp fiber surface at room temperature.
It does not vaporize, but it is exposed on the surface of pulp fiber by heat treatment
The above object is achieved by providing an absorbent article characterized by being a binder that exerts a tack force .

[0006]

The water-soluble binder in the above-mentioned absorber does not have tackiness (tack force) at room temperature, but develops a tack force when heated, so that pulp fibers and pulp fibers and a super absorbent polymer are mixed during molding of the absorber. Fully immobilize. Due to this strong fixing action, a large amount of superabsorbent polymer can be uniformly dispersed in the absorbent body, and the absorbent body itself can be retained in shape. Therefore, in the absorbent article including such an absorber, the shape of the absorbent article is prevented from losing its shape when wet, and the fitting property is sufficiently maintained. Further, since the absorbent body has sufficient liquid absorbing ability and is not affected by absorption inhibition, as a result, the absorbent article has improved body fluid absorbing performance.

[0007]

The absorbent article according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a perspective view of a disposable diaper as an embodiment of the absorbent article according to the present invention, and FIG. 2 is a partial cross-sectional view of the absorbent body of the disposable diaper of FIG. 1 and 2
As shown in FIG. 1, the absorbent article (disposable diaper 1) according to the present invention has a liquid-permeable topsheet 2, a liquid-impermeable backsheet 3, and an absorber 4 interposed therebetween. In this respect, the structure is similar to that of the conventional absorbent article. Thus, the absorbent body 4 is mainly composed of the pulp fiber 6 impregnated with the water-soluble binder and the super absorbent polymer 7.

Explaining this embodiment in more detail, the disposable diaper 1 comprises a top sheet 2, a back sheet 3, an absorber 4, and fasteners 5a, 5b, and the absorber 4 is a top sheet 2 and a back sheet. It is covered with 3.
The topsheet 2 is not particularly limited as long as it has sufficient liquid permeability, and examples thereof include a woven fabric, a non-woven fabric, and a porous sheet. Examples of the material thereof include pulp, rayon, polyester, polyethylene, Examples include polypropylene. The back sheet 3 is not particularly limited as long as it is a liquid-impermeable sheet that has been conventionally used for absorbent articles, and is liquid-impermeable and stretched by adding a filler to a thermoplastic resin. A vapor-permeable sheet that allows vapor to permeate is preferable, and a sheet having a feeling close to that of skin, for example, a composite material of the above film and a non-woven fabric, a composite material of a film and a woven fabric, or the like can be used.

As shown in FIG. 2, the absorbent body 4 is mainly composed of pulp fibers 6 and super absorbent polymer 7, and the pulp fibers 6 are impregnated with a water-soluble binder. The pulp fiber 6 is not particularly limited as long as it is one that has been conventionally used for an absorber, but the average fiber length of the pulp fiber is usually 0.8 in consideration of pulverization, lamination, compression treatment and the like.
It is desirable to be in the range of up to 5 mm.

The superabsorbent polymer 7 is not particularly limited as long as it has been conventionally used as an absorber, but the liquid absorption rate of the superabsorbent polymer is preferably 20 w / w% or more, In the case of particles, the particle size is 100-
It is preferably 800 μm. Specific super absorbent polymers include sodium polyacrylate, vinyl acrylate copolymer, crosslinked sodium polyacrylate, starch-acrylic acid graft polymer, isobutylene-maleic anhydride copolymer or saponified product thereof. Powders of potassium polyacrylate, cesium polyacrylate and the like are preferable. The superabsorbent polymer 7 is blended in an amount of 30 to 500% by weight with respect to the pulp fiber 6, but in the present invention, not only at a low content of 30 to 100% by weight,
Even in the case of a high content of not less than wt%, absorption of body fluid by the absorber is sufficient, and the shape retention of the absorber 4 itself is sufficiently maintained by the water-soluble binder described below. The position of the superabsorbent polymer 7 in the absorber 4 may be any of the upper layer, the middle layer, and the lower layer, but is not particularly limited as long as it can be uniformly dispersed at a desired position or the whole.

[0011] water-soluble binder, is at normal temperature does not exhibit tackiness at pulp fiber surfaces, is intended to exert tack force exposed to the pulp fiber surface by heat treatment.
Further, the water-soluble binder is dissolved in an organic solvent,
It is desirable that the fiber penetrates sufficiently from the surface of the fiber.
Such specific water-soluble binder,
Water-soluble polymers such as polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, acrylic acid copolymers, polyvinyl methyl ether, etc. are listed, and these water-soluble polymers include polyhydric compounds such as glycerin, sorbit, polyethylene glycol, pentaerythritol, etc. Tackifiers such as alcohol, polyethyleneimine and water-soluble salts of rosin, as well as crosslinking agents, fillers, stabilizers and colorants can be dissolved in other solvents such as water and alcohol to prepare a binder solution.

The method for impregnating the water-soluble binder may be a conventionally known method. For example, the pulp fiber impregnated with the water-soluble binder is obtained by immersing the pulp fiber in a water-soluble binder solution and then appropriately removing the liquid. To be In addition, spraying, gravure coating, and roll coating methods can also be used. Further, in the heat treatment, there are heat generation when the pulp sheet is opened by a mill, warm air treatment at the time of mixing and laminating, heat compression treatment by a heat roll, and the like. In particular, if the water content of the pulp fibers is raised to some extent in advance, the precipitation concentration of the binder is increased, and the adhesion between the pulp fibers 6, 6 or between the pulp fibers 6 and the superabsorbent polymer 7 can be increased. Water-soluble binder amount is preferably 5-5 0% by weight, and a water-soluble binder into a sheet 2
It is desirable that the probe tack force at 0 ° C. be 1 g / 5 mmφ or less.

In the disposable diaper 1 constructed as described above, there is no risk that the absorbent body 4 will be biased when worn, or will not be cracked even when compression or shear force is applied during the movement of the baby, and the absorption of body fluids will be inhibited. Sufficient absorption performance is exhibited without causing Although the above absorbent article has been described as a disposable diaper, in the case of a sanitary napkin or the like, the texture is good and there is no problem in the wearing feeling.

The performance of the examples according to the present invention will be shown in comparison with comparative examples. However, the present invention is not limited to the following examples. Example 1 A sheet-like pulp is impregnated with an aqueous solution of a polyvinyl alcohol-based water-soluble binder so that the binder content is 25% by weight with respect to the pulp. After drying this sheet-like pulp, it is pulverized with a chamasse mill. 150% by weight of super absorbent polymer was mixed with crushed pulp fiber, which was laminated and compressed to obtain a basis weight of 700.
An absorber having a g / m ² density of 0.2 g / cm ³ was prepared. Dispersion of this absorber, maximum absorption amount, liquid permeation rate was measured,
The results are shown in Table 1. In addition, the obtained absorbent body was used as the absorbent body of the above-mentioned disposable diaper, and the evaluation of the actual use of the disposable diaper was good without leakage of excrement or cracking of the absorbent body.

(Example 2) The content of the water-soluble binder was 1
A grammage of 70% was obtained by the same operation as in Example 1 except that the content was 0% by weight.
An absorber having a density of 0 g / m ² and a density of 0.2 g / cm ³ was prepared.
The dispersibility, maximum absorption amount and liquid permeation rate of this absorber were measured, and the results are shown in Table 1.

(Example 3) The sheet-like pulp was crushed with a camas mill, and the aqueous solution of the water-soluble binder used in Example 1 was added to the pulp fiber to adjust the water-soluble binder content to 25.
Spray to give a weight percentage. Along with this, a superabsorbent polymer was mixed with pulp fibers in an amount of 150% by weight, laminated and compressed to obtain a basis weight of 700 g / m ² and a density of 0.
An absorber of 2 g / cm ³ was prepared. Dispersibility of this absorber,
The maximum absorption amount and liquid permeation rate were measured, and the results are shown in Table 1.

Comparative Example 1 Pulp fiber and superabsorbent polymer were treated in the same manner as in Example 1 without impregnating a water-soluble binder, and the basis weight was 700 g / m ² and the density was 0.2 g / cm 2.
^Three absorbers were created. The dispersibility, maximum absorption amount and liquid permeation rate of this absorber were measured, and the results are shown in Table 1. Also,
The obtained absorbent body as an absorbent body of the above-mentioned disposable diaper,
In the evaluation using the disposable diaper actually, the absorbent body was cracked during use and the excrement could not be sufficiently absorbed, resulting in leakage.

[Measurement Method] (1) While disintegrating the dispersible pulp of the superabsorbent polymer, the superabsorbent polymer is mixed, and a mixture of the pulp fiber and the superabsorbent polymer is laid on a mount (see FIG. 2 and FIG. 5). At this time, the super absorbent polymer may be dispersed in the pulp fiber or may be dropped to the lower layer of the lower mount surface. The ratio of the superabsorbent polymer present in the pulp fiber was calculated by the following formula 1 and used as a numerical value representing the dispersibility of the superabsorbent polymer amount. The larger this value, the more the amount of superabsorbent polymer present in the pulp fiber, the more effectively the performance of superabsorbent polymer,
Absorption performance is improved. Further, the leakage of the super absorbent polymer from the inclusions such as the mount is reduced. a = [1-c / b] × 100 ... Equation 1 a: Proportion (%) of super absorbent polymer in pulp fiber b: Amount of super absorbent polymer in measured absorbent body (g) c: Mount Amount of highly water-absorbent polymer dropped on top (g)

(2) Maximum absorption amount The maximum absorption amount is 200 mm × 150 mm, and the absorbent body 4 is prepared. The absorbent body 4 is placed on the inclined surface of the inclined table having an inclination of 45 ° as shown in FIG. Predetermined injection point (140 mm from the end
X 75 mm). That is, to that point, 50 cc of physiological saline, which is equivalent to the amount of excretion of a single child, was injected at a rate of 5 cc / sec at 5-minute intervals. Here, the maximum absorption amount is the maximum amount of physiological saline that can be retained in the absorber. The maximum absorption that is considered necessary for a disposable diaper is four urine volumes (20
0cc), which was the target.

(3) Liquid passing speed of swelling absorber The absorber is cut to 55 mmφ and the upper surface mount is removed. This is placed on the 80 mesh wire net 42 at the bottom of the chromatographic tube 44 as shown in FIG. . Then cock 4
Closed physiological saline for 6 filled to a height of 400mm from the sample bottom, after the absorber has equilibrium swell, opening the cock 46, commentary lines between H _a -H _b (300mm~200mm: 100c
The time t passing through c) is read, and the liquid passing speed S is obtained from the following equation 2. S (cc / min.) = 100 (cc) × 60 / t (sec.) ... Equation 2

(4) Initial adhesion force Measured according to ASTM D 2979. That is, a stainless steel (SUS304) smooth-surfaced cylinder (referred to as a probe) having a diameter of 5 mm was adhered to the surface coated with the self-adhesive composition for 1 second while applying a load of 100 g, and then the probe was applied at a speed of 10 mm per second. The resistance value when peeled from the coated surface in the vertical direction was measured, and this was taken as the initial adhesive strength.

[0022]

[Table 1]

[0023]

EFFECTS OF THE INVENTION The absorbent article according to the present invention can maintain an excellent bodily fluid absorbing ability and an excellent fitting property without damaging the absorbent body or losing its shape.

[Brief description of drawings]

FIG. 1 is a perspective view of a disposable diaper that is an embodiment of an absorbent article according to the present invention.

FIG. 2 is a partial cross-sectional view of an absorbent body of the absorbent article of FIG.

FIG. 3 is a perspective view of a measuring device that measures liquid absorbency of an absorber or the like.

FIG. 4 is a side sectional view of a measuring device for measuring a liquid passing speed of a swelling absorber.

FIG. 5 is a partial cross-sectional view of an absorbent body of a conventional absorbent article.

[Explanation of symbols]

1 disposable diapers 2 Top sheet 3 back sheet 4 absorber 6 pulp fiber 7 Super absorbent polymer 8 hydrophilic long fibers

Claims (2)

(57) [Claims] 1. An absorbent article having a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorbent body interposed therebetween, wherein the absorbent body is a pulp impregnated with a water-soluble binder. Mainly composed of fibers and super absorbent polymer ,
Water-soluble binder tacks on pulp fiber surface at room temperature
It does not exert its power, but it is heated on the pulp fiber surface
An absorbent article, which is a binder that exhibits tackiness when exposed . 2. The absorbent article according to claim 1, wherein the impregnated amount of the water-soluble binder is 5 to 50% by weight based on the pulp fiber.