JPH0614945B2 - Sanitary napkin - Google Patents

Description

TECHNICAL FIELD The present invention relates to a sanitary napkin, and more particularly to a sanitary napkin having reduced absorption characteristics, particularly lateral leakage.

[Conventional technology and problems]

Research has been conducted for the purpose of improving the absorption characteristics of water-absorbent articles, and many results have been reported. Most of the goals are to improve the liquid absorption speed, prevent the liquid from returning to the surface from the water absorption layer after the liquid absorption, and reduce stickiness on the surface. As a specific example, as a study on the surface material, there was stickiness on the surface because rayon staple, which has been generally used conventionally, is a hydrophilic material. It has been proposed to change this to a hydrophobic material such as polypropylene staple or polyester staple to reduce the stickiness of the surface. Also, as a material for the water-absorbing layer, the absorption capacity is improved by applying a polymer absorbent material (superabsorbent polymer) which is improved in that the holding power after absorption of conventional absorbent paper and cotton-like pulp is improved, At the same time, it has been proposed to prevent the liquid from returning to the surface material after absorption. In fact, these proposals have greatly improved the water absorption capacity itself. Therefore, it can be said that the problems such as leakage due to the shortage of absorption capacity have been considerably solved. In addition, the retention of super absorbent polymer due to absorption and swelling is overwhelmingly higher than that of conventional absorbent paper and cotton-like pulp. The liquid return to the surface afterwards) is reduced, and its benefit is great.

Therefore, it can be said that the research goals of sanitary napkins were focused on how to effectively construct superabsorbent polymers. And the result is Sho 57-56
No. 561 and Japanese Patent Publication No. 57-6946.

However, the present inventors believe that no matter how effectively the materials such as the superabsorbent polymer are configured, the absorption characteristics are still insufficient, and in particular, they have not been solved as a measure against lateral leakage. However, the present inventors do not completely deny these materials. Absorbent paper and cotton-like pulp, which are the basic materials that make up a sanitary napkin, have hydrophilicity as their absorption characteristics, absorption / diffusion property due to the appropriate density, price, etc. It is considered to be an effective material. The only drawback is that its shape retention (against pressure repulsion), which is relatively good before absorption (dry state), drops significantly after absorption (wet state) (so-called fatigue). It is difficult to recover once the repulsive force disappears and it is deformed once, and this tendency is especially seen in cotton-like pulp.

This state is also apparent from the napkin shape after mounting as shown in FIG. 9, and when it is set to this deformation (this is called twisting), leaks, especially from the side of the central portion, occupy most of it. It is a thing. In other words, when the central part of the sanitary napkin is wet after blood absorption, its repulsive force is small against the pressure between the crotch of its closed legs, walking, etc., causing twisting, and the blood absorbing part (the width of the napkin if worn correctly It is considered that the leakage occurred while leaving a distance between the both ends (almost the central portion in the direction).

Therefore, as a means for solving these problems, the actual exploitation of Sho 59-19
As seen in Japanese Patent No. 0235, the sanitary napkin has a required bending resistance of 50 to 90 mm in the center and 20 to 4 in the width.
It is proposed to place a 0 mm mold retention piece. Then, considering this proposal, it seems that the above problems were solved very efficiently, but it cannot be said that the effect is still insufficient and it is not an essential solution. As described above, it cannot be said that the cause of the lateral leak is the factor in the central portion in the width direction, but the greatest point is the deformation of both ends of the sanitary napkin. It is also proved by "Human Anatomy Diagram, Fig. 10". That is, in Japanese Utility Model Laid-Open No. Sho 59-190235, the portion where the shape-retaining piece is arranged (the portion to which the napkin is attached) has a gentle curved surface, and a substantially constant curved surface is maintained even in a closed leg or walking state. Of. In other words, the impact resilience of the sanitary napkin attached to this part is
It is unusually thick as its product design, and is not so necessary unless it has a shape that does not fit on this surface. Therefore, even if the shape-retaining piece is formed only in the central portion, twisting at both ends, which is the main factor, cannot be prevented, and leakage cannot be sufficiently prevented. This point is also clear in the comparative example described later.

As described above, it is difficult to find a method of preventing deformation of the sanitary napkin during use and effectively preventing lateral leakage without impairing the feeling of use with the current methods.

[Means for solving problems]

Therefore, in view of the above-mentioned problems, the present inventors, without impairing the feeling of use, prevent the sanitary napkin from being deformed or twisted during use, and also improve the fit to the pubic area and the crotch area. As a result, the present invention has been completed as a result of intensive research on the structure of the sanitary napkin that effectively prevents lateral leakage.

That is, the present invention is a substantially vertical sanitary napkin having an elastic restoring sheet located below the water absorbing layer and having substantially the same size as the water absorbing layer, in which both longitudinal center portions of the elastic restoring sheet are located. The present invention relates to a sanitary napkin, characterized in that a slit is formed through the sheet.

In the present invention, the elastically restoring sheet means a sheet on which a force acts to return to the original state due to deformation.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

An example of a typical constitution of a conventional sanitary napkin is shown in FIG. 8, which is a rayon staple cotton 2 laminated on a water-absorbing layer composed of cotton-like pulp 3, absorbent paper 4, superabsorbent polymer 5, and the like. The lower part and the side parts of these are covered with a poly-laminar waterproof paper 6, and these are covered with a surface material 1 to provide a slip prevention material 7.

Also, in FIG. 10, as described above, a model-retaining piece (elastic restoring sheet) 8 is arranged at the center of the sanitary napkin.
The structure of the sanitary napkin disclosed in Japanese Patent No. 190235 is shown.

However, in these conventional sanitary napkins, as shown in FIG. 11 and FIG. 12, when they are attached to the crotch and absorb blood, lateral leakage occurs due to the small repulsion at both ends.

Therefore, in order to effectively prevent the lateral leak that occurs due to such a cause, the inventors of the present invention also prevent the center end portions from being deformed by some method, and after the deformation. In this case, it was necessary to provide both ends with the characteristic of restoring the normal shape (fitting to the crotch shape). As a countermeasure against this, first, it is easy to conceive of forming a sheet-like material having elasticity over the entire surface. Therefore, the inventors of the present invention also examined how much this method would improve, and required considerable rigidity (elasticity) to sufficiently prevent the deformation of both ends, and such a sanitary napkin was actually used. It is uncomfortable when worn, which is not preferable, since it is different from the above-mentioned "without impairing the usability". In addition, if importance is attached to the point that does not impair the feeling of use, there is no choice but to cope with a decrease in rigidity (elasticity), and as a result, a sufficient deformation prevention effect is not seen and it is not an essential solution. It was revealed.

Therefore, the present inventors further proceeded with the study by thinking as follows. In other words, as described above, it is essential to prevent deformation of both ends of the sanitary napkin, and in that respect, basically a sheet-like material having rigidity (elasticity) that sufficiently prevents deformation of both ends should be constructed. The purpose is achieved with. I focused my research on how to reduce the feeling of discomfort. As a result, as shown in FIGS. 1, 2 and 3, a sheet-like material (hereinafter referred to as an elastic restoring sheet) 8 having elasticity substantially the same size as the water absorption layer of the sanitary napkin penetrates the sheet at both ends thereof. By providing the slits 9 that are open on the upper and lower surfaces, the above problem can be solved, that is, the discomfort can be reduced and the use can be improved.

This will be described with reference to the drawings. First, a schematic cross-sectional view of the central portion of the sanitary napkin at the time of wearing is shown in FIGS. 4 and 5 for each case. When the slit 9 is not provided, the resilience (elasticity) to the inside of the crotch part as described above.
Also, since the strain is distributed over the entire length in the longitudinal direction and there is no relaxation point, the total repulsive force generated from the entire width and the entire length is large, which is very uncomfortable (see FIG. 13). On the other hand, in the case of the elastic restoring sheet of the present invention,
As shown in FIGS. 4 and 5, the sectional shape shows a convex shape (mountain shape) that exactly matches the crotch shape itself. In addition, since the width of the end portion separated through the slit is narrow, the force required for bending is small and the deformation into that shape is very easy (low load).

The first embodiment of the elastic restoring sheet of the present invention is
A few examples are shown in FIGS. 2 and 3, but it is basically preferable that the sanitary napkin has a single slit or a plurality of slits at both ends of the approximate center. Specifically, as shown in FIG. 1, one side 15 is centered on the longitudinal symmetry line 10 of the sanitary napkin.
Length 30 mm or more 8 mm (30 mm for both) apart
It is effective to provide a linear slit 9 of 0 mm or less in the longitudinal direction. Further, the slit length is preferably in the range of 40 to 60 mm. If the length of the slit is less than 30 mm, an uncomfortable feeling is generated, and if it exceeds 80 mm, the uncomfortable feeling is improved, but the effect of preventing the sanitary napkin from being twisted is reduced, which is outside the object of the present invention. Similarly, as shown in FIG. 2, it is effective to provide a plurality of slits 9 from a portion distant from the symmetry line 10 by 15 mm or more on one side toward both ends. The number of slits is preferably 2 or more, and more preferably 3 to 4 in practice. A feeling of strangeness occurs with one, and
When the number is more than the number, the anti-twist effect is reduced and the object of the present invention is deviated. Further, as shown in FIG. 3, the combination of slits shown in FIGS. 1 and 2 is also effective.

Further, the material of the elastic restoring sheet of the present invention is not particularly limited, but any sheet-shaped material having elasticity and restoring property against deformation in the width direction may be used. Specific examples include polyolefin-based, polyurethane-based, polydiene-based compounds and the like, and the form thereof is a single film,
A foam, a non-woven fabric having a restoring property, or a laminate with such a sheet-like material is also applicable. More specifically, foamed polyethylene, polybutadiene, the same foamed material, polyethylene, polypropylene rubber and the like are preferable in view of cost. The thickness of the elastic restoring sheet of the present invention depends on its material, but is generally 4 mm or less, and preferably 2 mm or less in the sense that it does not cause a feeling of strangeness.

〔Example〕

Next, the effects of the present invention will be described with reference to examples. Example 1
~ 9 and Comparative Examples 1 to 3 As a test piece, the water absorbing layer is 2.1 g of cotton-like pulp (NBKP).
1.2g, 0.3g super absorbent polymer, 18g / m ² heat bond type polyolefin (35% polypropylene, 65% polyethylene-polypropylene composite fiber) surface material, and Table 1 for elastic restoration sheet. The ones shown were used.

The composition was evaluated as shown in FIG. 6 or 7, and the lateral leakage preventing effect and the uncomfortable feeling when worn were evaluated.

As a comparative example, the performance of the above-mentioned conventional sanitary napkin was also evaluated. The lateral leak prevention effect was evaluated using a female waist operating human body model 12 capable of opening and closing legs as shown in FIG. In other words, test sample 11
As shown in Fig. 15, the human body model 12 was attached to the model, and equine defibrinated blood was infused from the tube 13 at a rate of 5 g / min under a walking exercise condition of 70 m / min. Stopped and measured as maximum absorption. And the data was arranged as the leakage measurement rate at the time of absorbing 3 g and 5 g.
The test was performed 10 times for each sample.

The results are shown in Table 1.

[Brief description of drawings]

1, 2 and 3 are plan views showing an embodiment of the elastic restoring sheet of the present invention, and FIGS. 4 and 5 are schematic sectional views showing a state in which the sanitary napkin of the present invention is mounted. FIGS. 6, 6 and 7 are sectional views showing an embodiment of the sanitary napkin of the present invention, FIGS. 8 and 10 are sectional views of a conventional sanitary napkin, and FIG. 9 is a conventional sanitary napkin. FIG. 11 and FIG. 12 are perspective views showing the shape of the conventional sanitary napkin after mounting, and FIG. 13 shows the state when the comparative product is mounted. FIG. 14 is a schematic sectional view, and FIGS. 14 and 15 are diagrams showing a female waist movable human body model capable of opening and closing legs. 1: Surface material, 2: Rayon staple cotton 3: Cotton pulp, 4: Absorbent paper 5: Highly absorbent polymer 6: Polylamin waterproof paper 7: Anti-slip material, 8: Elastic restoration sheet 9: Slit, 10: Longitudinal Line of symmetry 11: test sample, 12: human body model 13: tube

Claims (3)

[Claims] 1. A substantially vertical sanitary napkin having an elastic restoring sheet located below the water absorbing layer and having substantially the same size as that of the water absorbing layer. A sanitary napkin characterized by having a slit penetrating the sheet. 2. A slit having a length of 30 mm or more and 80 mm or less is provided in a longitudinal direction at a portion separated by 15 mm or more on one side from a line of symmetry in the longitudinal direction of the sanitary napkin.
The sanitary napkin according to the item. 3. The sanitary napkin according to claim 1 or 2, wherein slits are provided from a portion distant from the longitudinal symmetry line of the sanitary napkin by 15 mm or more on one side toward both ends.