JP3997355B2 - Sanitary napkin - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sanitary napkin .
[0002]
[Prior art]
Conventionally, an absorbent body in which particles of a superabsorbent polymer (hereinafter also referred to as SAP) are dispersed in a pulp fiber aggregate has been widely used, but the SAP particles are not fixed to the fibers. In order to solve this problem, SAP particles are unevenly distributed in the absorbent body, and a composite absorbent body composed of a fiber aggregate and SAP fixed to the fiber by polymerization on the fiber surface is proposed. (See Patent Documents 1 and 2). Such a composite absorbent body is manufactured through a monomer application step for applying an SAP monomer solution to a fiber assembly and a polymerization step for polymerizing the monomer solution held in the fiber assembly.
[Patent Document 1]
Japanese Patent Publication No. 7-74277 [Patent Document 2]
Japanese Examined Patent Publication No. 7-64896 [0003]
[Problems to be solved by the invention]
However, the conventional composite absorber has a problem that it becomes poor in flexibility when the amount of absorption is increased or the thickness is reduced due to its structure.
[0004]
Therefore, a main problem of the present invention is to provide a technique that does not deteriorate flexibility even when increasing the amount of absorption or reducing the thickness, and that does not impair the advantages of the composite absorber.
[0005]
[Means for Solving the Problems]
The present invention that has solved the above problems is as follows.
<Invention of Claim 1>
Fiber assembly consisting of a nonwoven fabric and has a superabsorbent polymer which is fixed on the fiber by the polymerization of acrylic monomer in the fiber surface, an absorbent body having a function of absorbing and retaining body fluids, and corresponding excretory organs of the body fluid A sanitary napkin provided as a main absorbent containing a portion to be
The basis weight of the fiber assembly is 5 to 70 g / m ^2, and the basis weight of the superabsorbent polymer to the fiber assembly is 50 to 100 g / m ² ,
The initial thickness T0 of the absorber is 0.3 to 3 mm;
The absorbent body has a structure breakage portion formed by locally breaking the fixing structure of the superabsorbent polymer to the fiber and the cross-linking structure of the fibers by the superabsorbent polymer by an external force by embossing. Many are arranged, and
The number of the structural destruction parts in the product front-rear direction intermediate part including the body fluid receiving part is less than other parts, thereby changing the degree of structural destruction according to the part of the absorber,
A sanitary napkin characterized by that.
[0006]
(Function and effect)
As a result of diligent research, the present inventors have found that an absorbent body having a superabsorbent polymer anchored to a fiber by polymerization on the fiber aggregate and its fiber surface has a structure in which the superabsorbent polymer anchoring structure and the superabsorbent polymer are bonded to each other. Focusing on the fact that the cross-linked structure has increased rigidity, the present invention has found that such a structure can be destroyed in part or all of the absorbent body and the flexibility can be improved without losing the advantages of the composite absorbent body. It was made.
[0007]
In this invention, since the softness | flexibility of an absorber can be adjusted with the grade of structural destruction, an absorber as shown, for example to the following (A)-(C) can be obtained.
[0008]
(A) An absorbent body that is superior in both the amount of absorption and flexibility by making the amount of the superabsorbent polymer significantly larger than before and performing sufficient structural destruction.
[0009]
(B) An absorbent body that is extremely excellent in flexibility, although the amount of superabsorbent polymer is the same level as before, and sufficient structural destruction is performed, so that the amount of absorption is not different from the conventional one.
[0010]
(C) An absorbent body that has a remarkably superior absorption capacity by making the amount of the superabsorbent polymer significantly larger than before and performing the minimum structural breakage, although the flexibility is the same as before.
[0011]
[0012]
Also, those that locally collapse the structure, such as embossing, and those that break the structure, such as needle puncture, are preferred because they do not destroy the shape of the absorbent body . Since it is widely used in the field of napkins , it is easy to apply and has the advantage that the diffusibility of the absorbent can be adjusted by the pattern.
[0013]
[0014]
Further, in the composite absorbent, the amount of absorption can be increased by increasing the amount of SAP, but in the conventional one, the hardness of the fixed SAP becomes remarkable and the flexibility becomes poor. However, since the absorbent body of the present invention is softened by structural destruction, even if the absorption amount is increased by increasing the SAP amount as in the present invention, hardening due to the increase in SAP amount is suppressed.
[0015]
[0016]
Further, when the conventional composite absorbent body is thinned, the fiber assembly is compressed prior to SAP application, but in this case, the structure becomes dense and the flexibility becomes poor. However, since the absorbent body of the present invention is softened by structural destruction, even if it is extremely thin as in the present invention , hardening due to the densification of the structure is suppressed.
[0017]
Note that the initial thickness T0 according to the present invention, using a Kato Tech Co. KES-G5 tester, with the following settings: means the thickness when a load is applied to 0.5 gf / cm ^2.
・ SENS: 2.0
・ Type of force meter: 1kg
・ Speed range: 0.1cm / second
・ DEF sensitivity: 20mm / 10V
・ Pressure area: 2cm ²
・ Capture interval: 0.1 seconds
・ Stroke set: 5.0 (upper limit load 50 gf / cm ² )
Initial thickness T0: thickness when a load of 0.5 gf / cm ² is applied to the sample
<Invention of Claim 2 >
The sanitary napkin according to claim 1, wherein a cushion layer is provided on at least one of the upper side and the lower side of the absorbent body.
[0019]
(Function and effect)
According to the absorbent body of the present invention, although the flexibility is improved, the cushioning property is not improved so much. Therefore, in order to increase the cushioning property at the expense of thinning, it is preferable to provide a cushion layer as described in this section.
[0020]
[0021]
[0022]
[0023]
(Function and effect)
In the present invention, the body fluid receiving portion has higher rigidity than the other parts, and deformation such as twisting does not easily occur even when an external force generated with the movement of the wearer is received, so that body fluid does not easily leak. On the other hand, the other parts have low rigidity and are easily deformed according to the movement of the body, so that the wearer has a soft and good fit.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 shows an outline of a manufacturing flow of an absorbent body according to the present invention. That is, first, the superabsorbent polymer monomer solution 2L is applied to the fiber assembly 1 made of a nonwoven fabric . As the nonwoven fabric, short and bulky nonwoven fabrics such as air-through nonwoven fabric, SMS nonwoven fabric, and melt blown nonwoven fabric are preferably used. The basis weight of the fiber assembly is 5 to 70 g / m ² from the viewpoint of thinning . In particular , the basis weight of the fiber assembly is preferably 10 to 40 g / m ² .
[0025]
A known acrylic acid monomer is used for the monomer solution . When SAP formation is performed by copolymerization, two or more kinds of monomers can be used. What is necessary is just to determine the provision amount of a monomer suitably according to the fabric weight of SAP in an absorber. SAP of basis weight, and 50~100g / m ^2. As the monomer application method, it is preferable to spray the monomer solution with a particle size of micron order on the fiber assembly 1 using the spray device 2 as shown in the figure, but the monomer solution is applied to the outer peripheral surface. An application method in which the fiber aggregate is brought into contact with a roll or a dipping method in which the fiber aggregate is immersed in the monomer solution can also be employed.
[0026]
The monomer imparted to the fiber assembly 1 is polymerized. For the initiation of polymerization, a polymerization initiator can be used, or electromagnetic radiation, fine particle ionizing radiation, or the like can be used by a radiation irradiation device 3 as shown in the figure. In the former case, a monomer solution in which a monomer and a corresponding polymerization initiator are mixed may be applied to the fiber assembly, a polymerization initiator is applied to the fiber assembly after the monomer solution is applied, or On the contrary, the monomer solution is applied to the fiber assembly to which the polymerization initiator is previously applied. As the polymerization initiator, for example, an inorganic or organic peroxide such as persulfate or hydrogen peroxide can be used.
[0027]
Thus, a composite 1C composed of the fiber assembly and the superabsorbent polymer fixed to the fiber by polymerization on the fiber surface is obtained. Although the structure of the composite 1C varies depending on the density of the fiber assembly 1, the application form and the application amount of the monomer solution, the SAP 11 is coated so as to coat a part or all of the surface of the fiber 10 as shown in FIG. And the fibers 10 and 10 are cross-linked by a part of the fixed SAP 11.
[0028]
Conventionally, since the composite 1C was used as an absorbent as it was, only a poorly flexible one was obtained. However, in the present invention, an external force is further applied to a part or all of the composite 1C to fix the bonded SAP11 or the crosslinked structure. The softening process which destroys is done. Reference numeral 4 in FIG. 1 indicates an external force applying device for the softening process. In the illustrated example, it is assumed that the composite 1C is softened in the state of a belt-like sheet and then cut into a predetermined shape and size. However, the softening is performed after cutting and before being incorporated into the absorbent article. You can also.
[0029]
The softening process is performed by embossing . Preferred for embossing is to destroy crushed locally structure. The external force imparting device 4 in this case is configured to sandwich the fiber assembly 1C between an embossing roll having a large number of convex portions arranged on the outer peripheral surface and a support roll. In particular, embossing is widely applied in the field of sanitary napkins , so that it is easy to apply, and the pattern has the advantage that absorption characteristics such as diffusibility of the absorbent can be adjusted.
[0030]
As can be seen from this, the softening process of the present invention is to arrange a large number of local destruction parts at predetermined intervals in the processing target range by embossing.
[0031]
In addition, the structural destruction of the present invention is applied uniformly to the entire absorbent body 20 as illustrated in FIG. 3, and is not made uniform and flexible as illustrated in FIGS . 4 and 5. The degree of structural destruction is changed according to the site of the absorber 20. The code | symbol 21 has shown the structural destruction part (The pressing part by embossing etc.).
[0032]
More specifically, in the example shown in FIG. 4 and FIG. 5, the degree of structural destruction in the part M including the body fluid receiving part Z, that is, the intermediate part in the product front-rear direction in the sanitary napkin is less than in other parts (FIG. 4). Suitable for the case where so-called side leakage prevention is important, since the part M is more rigid than other parts and becomes difficult to twist. It is a thing. Incidentally, FIG. 4 and reference numeral 30 in FIG. 5 shows the outline of the article, in this view is assumed sanitary napkin.
[0033]
The degree of softening of the absorbent body 20 is adjusted by the numerical density of the structural destruction part 21. For example, as shown in FIG. 5, even if the degree of softening per structural fracture portion is the same, the flexibility is remarkably increased by increasing the number of structural fracture portions 21 per unit area. By reducing the amount, the degree of softening can be moderately suppressed.
[0034]
As for the thickness of the absorber 20, the initial thickness T0 according to the above definition is 0.3 to 3 mm . In particular , the initial thickness T0 is preferably 0.4 to 1.5 mm. For this reason, it is possible to compress the fiber assembly prior to SAP application or after SAP application and before structural destruction, or to compress the absorbent body after structural destruction.
[0035]
In the absorbent body 20 according to the present invention thus obtained, after the polymerization of the monomer solution applied to the fiber assembly 1, when the structure is destroyed by applying an external force to a part or all of the composite 1 </ b> C, this is not performed. The flexibility can be improved as compared with the above. In other words, depending on the application of the product, in addition to the absorber that is superior in both absorption amount and flexibility, the absorber that is not much different from the conventional absorption amount but the flexibility is excellent, and the flexibility is the same as the conventional one. Although it is not, it becomes possible to produce an absorbent body that is remarkably excellent in absorption.
[0036]
On the other hand, in the present invention thus obtained that intake absorbent body 20, Ru is used as the primary absorbent member including a portion corresponding in physiology napkin down and excretion organs of the body fluid. And in this case, without compromising the advantage of using the composite absorbent body, that is, the advantage of preventing uneven body fluid absorption due to the uneven distribution of the superabsorbent polymer, it is possible to improve the amount of absorption, flexibility, and thinning of the body fluid absorbing portion. it can.
[0037]
However, according to the absorbent body of the present invention, although the flexibility is improved, the cushioning property is not improved so much. Therefore, in order to increase cushioning at the expense of thinning, as shown in FIG. 6 , at least one of the upper side and the lower side of the absorbent body 20 in the sanitary napkin 30, particularly the fit to the wearer is also improved. For this purpose, it is preferable to provide a cushion layer 40 at least above the absorbent body 20 as shown in the figure. The cushion layer 40 can be formed of a material known in the field of sanitary napkins , for example, cotton sponge, sponge, or a mixture thereof.
[0038]
In the illustrated example, it is made of a liquid-permeable non-woven fabric, a perforated film sheet, etc., and a substantially rectangular surface sheet 31 provided on the side facing the body skin so as to directly touch the wearer's skin, The absorbent body 20 is provided between a substantially rectangular liquid-impervious back sheet 32 made of a polyethylene plastic film or the like provided on the side away from the skin, and the upper surfaces of both sides of the top sheet 31 and both sides of the back sheet 32. The leak-proof material 33 is disposed so as to straddle the upper surface of the part, and is fixed to both sheets 31 and 32 by a hot melt adhesive or the like, and the cushion layer 40 is between the top sheet 31 and the absorbent body 20. Is arranged.
[0039]
When the cushion layer 40 is provided, as shown in the figure, by providing a hydrophilic layer 41 having a higher hydrophilicity than the cushion layer 40 between the cushion layer 40 and the absorber 20, the cushion layer 40 and the absorber 20 side are provided. It is preferable because the body fluid permeability to the body improves and the body fluid reaching the hydrophilic layer 41 diffuses well in the layer and is absorbed by the absorbent body 20 in a wider range. The hydrophilic layer 41 can be formed of water-absorbing paper such as tissue paper, a nonwoven fabric made of natural or synthetic hydrophilic fibers, a pulp sheet, or the like, and can be disposed so as to wrap the entire outer surface of the absorbent body 20 as shown.
[0040]
【The invention's effect】
As described above, even if the amount of absorption is increased or the thickness is reduced, the flexibility does not become poor, and the advantages of not damaging the advantages of the composite absorbent are brought about.
[Brief description of the drawings]
FIG. 1 is a flowchart showing an example of an absorbent body manufacturing procedure according to the present invention.
FIG. 2 is a schematic view showing the structure of a composite absorbent body.
FIG. 3 is a plan view of an absorbent body according to the present invention.
FIG. 4 is a plan view of an absorbent body according to the present invention.
FIG. 5 is a plan view of an absorbent body according to the present invention.
FIG. 6 is a plan view of an absorbent body according to the present invention.
FIG. 7 is an enlarged vertical cross-sectional view of a main part of an absorbent body showing various examples of softening adjustment.
FIG. 8 is a fragmentary perspective view of a sanitary napkin according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Fiber assembly, 2 ... Spraying device, 3 ... Radiation irradiation apparatus, 4 ... External force provision apparatus, 10 ... Fiber, 11 ... Superabsorbent polymer (SAP).

Claims (2)

Corresponding to a body fluid excretion organ, a fiber assembly made of non-woven fabric and a superabsorbent polymer fixed to the fiber by polymerization of acrylic acid monomer on the fiber surface and having the function of absorbing and holding body fluids A sanitary napkin provided as a main absorbent containing a portion to be
The basis weight of the fiber assembly is 5 to 70 g / m ^2, and the basis weight of the superabsorbent polymer to the fiber assembly is 50 to 100 g / m ² ,
The initial thickness T0 of the absorber is 0.3 to 3 mm;
The absorbent body has a structure breakage portion formed by locally breaking the structure of fixing the superabsorbent polymer to the fiber and the cross-linked structure of the fiber with the superabsorbent polymer by an external force by embossing. Many are arranged, and
The number of the structural destruction parts in the product front-rear direction intermediate part including the body fluid receiving part is less than other parts, thereby changing the degree of structural destruction according to the part of the absorber,
A sanitary napkin characterized by that. The sanitary napkin according to claim 1, wherein a cushion layer is provided on at least one of the upper side and the lower side of the absorbent body.

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