CA1298684C

CA1298684C - Sanitary napkin

Info

Publication number: CA1298684C
Application number: CA000537869A
Authority: CA
Inventors: Akira Sakurai; Toshihiro Shirose
Original assignee: Kao Corp
Current assignee: Kao Corp
Priority date: 1986-05-26
Filing date: 1987-05-25
Publication date: 1992-04-14
Anticipated expiration: 2009-04-14
Also published as: PH23954A; EP0474317A1; DE3786371T2; EP0248584A3; ES2098315T3; EP0474317B1; US4798601A; MY100853A; HK49994A; DE3786371D1; EP0248584B1; DE3752024T2; DE3752024D1; EP0248584A2; ES2041263T3

Abstract

ABSTRACT OF THE DISCLOSURE
A sanitary napkin comprises a liquid-permeable surface sheet, a liquid-impermeable leakproof sheet, and an absorbent body between the surface sheet and the leakproof sheet. The absorbent body comprises a first absorbent paper sheet, a second absorbent paper sheet and an absorbent material between the two papers. The first absorbent paper sheet covers at least a part of the second absorbent sheet, and the first absorbent paper sheet is fixed at a portion thereof covering the second absorbent paper sheet to the leakproof sheet. The absorbent body may be composed of two absorbent material layers including an upper layer having a width smaller than a lower layer.

Description

~9~68~ 5702-267 The present invention relates to a sanitary napkin for absorbing menstrual blood of womenO
Brief Description of the Drawings:
Figs. 1 to 4 show examples of a sanitary napkin according to the present invention, among which Figs. 1 and 2 are transverse crosssectional views of the napkin, while Figs. 3 and 4 are longitudinal crosssectional views thereof. Figs. 5 to 7 are transverse crosssectional views of a napkin according to the prior art. In these Figures, the reference numerals have the following meanings:
l...surface sheet 2,2'...absorbent paper sheet 21...first absorbent paper sheet 22second absorbent paper sheet 3... leakproof sheet 4... cottony pulp 5... highly absorbent polymer 6... cottony staple ~ 7... shift-inhibiting means `~ 20 8... bonded area Fig. 8 is a transverse crosssectional view of a model of a sanitary napkin according to -the present invention. Fig. 9 shows an example of a sanitary napkin according to the present invention wherein (a) is a plan view and (b) is a crosssectional view taken along line X-X'. Fig. 10 is a transverse crosssectional view of another example of a sanitary :

.~; - 1 -.

~L29~6~

napkin according to the present invention. Fig. 11 is a perspective view of a sanitary napkin after it is applied to a crotch.
In these figures, the reference numerals have the followiny meanings:
31...first absorbent layer 32...second absorbent layer 33...bonding between the first absorbent layer and the second absorbent layer 34...leakproof sheet 35...surface sheet 36,36'...bonding between khe surface sheet and the leakproof sheet 37...bonding between the leakproof sheet and the first absorbent layer 38...pressure-sensitive adhesive tape 39...flap 40,40' ...absorbent paper sheet 41 ...cottony pulp 42 ...highly absorbent polymer 43 ...rayon staple Figs. 13 (a) through (d) are plan views of examples of arrangements of slip inhibitor means of a sanitary napkin according to the present invention. Figs. 14 (a) through (d) are plan views of arrangements of slip inhibitor means of a napkin according to the prior art. Fig. 12 is a plan view of the form of a sanitary napkin taken when the napkin is applied to the crotch or when the wearer assumes various postures. In this Figures, the reference numerals have the following meanings:

`` ~LZ91368~

101 : double-coated adhesive tape 102 : hot-melt adhesive 103 : area wherein significant deformation occurs in use 104 : area wherein little deformation occurs in use 105 : slip inhibitor means 106 : release paper 107 : area to be held by a wearer when the napkin is applied to the crotch 108 : concave line of or formed by connecting front ends of slipping-off inhibiting means Statement of the Prior Art An ordinary sanitary napkin comprises an absorbent body ~ or layer made of absorbent paper or fluffy pulp, (called also : cottony pulp), a liquid impermeable leakproof sheet (or material) covering the bottom and both sides of the absorbent layer, a liquid-permeable surface sheet (or material) covering the whole of the absorbent layer covered with the leakproof sheet and a shift-inhibiting tape attached on the non-use face, as shown, for example, by numeral 7 in Fig. 5 wherein numeral 1 i5 the surface ~: material, numeral 2 is the absorbent layer, numeral 3 is the leakproof material.
Nowadays, a polymeric absorbent material is frequently used as a component constituting the absorbent layer of a sanitary napkin for the purpose of enhancing the absorption capacity of the napkin, as shown, for example, i Fig=. 6 and 7 wherein nu=eral 2' . . , :, .

~' ~29~6~

is absorbent paper sheet for piling cottony pulp, numeral 4 is cottony pulp, numeral 5 is the polymeric absorbent material and numeral 6 is cottony staple.
Although a sanitary napkin containing a polymeric absorbent material as described above has been generally thought to exhibit an enhanced absorption capacity, the following problems have not been solved as yet.
For example, with respect to the napkin shown in Fig. 6, the polymeric absorbent material 5 is present near the non-use surface. Therefore, when the amount of menstrual blood is small, the blood is absorbed and kept by only the cottony pulp 4 or the absorbent paper 2', which is an ordinary absorbent material according to the prior art, so that the blood does not reach the polymeric absorbent material 5. Thus the polymeric absorbent ; material 5 is not effectively used. Further, when the cottony pulp 4 and the absorbent paper 2' are piled to produce an absorbent layer these constituent members each tend to shift and the cottony pulp tends to scatter from the edge thereo-f. The scattering cottony pulp adheres to some area of the processing line or falls down, giving a contaminated product which is unfavorable for sanitary reasons.
On the other hand, the napkin shown in Fig. 7 con-tains an absorbent layer produced by spraying a cottony pulp 4 with a polymeric absorbent material 5 and folding the resulting pulp at ~ both ends into an "e"-shape.
In this napkin, the shifting of the constituent members caused in the production of the absorbent layer is remarkably ~2986~

reduced as compared with that of the napkin shown in Fig. 6.
However, the scattering of cottony pulp still occurs from the area b, and thus the problem has not been solved completely.
The napkin shown in Fig. 7 exhibits absorption better than that shown in Fig. 6, because the polymeric absorbent material 5 is positioned closer to the use face (which is the top face in Figs. 6 and 7)in the former than the latter. The former is superior to the latter in the effective utilization of the polymeric absorbent material. Accordingly, when the amount of menstrual blood is small, the napkin shown in Fig. 7 exhibits sufficient absorption unlike the napkin shown in Fig. 6. However, when the amount of menstrual blood is large, the amount of the menstrual blood to be absorbed per unit volume of the absorbent layer, exceeds the absorption capacity of the absorbent layer, because the absorbent layer does not contain any material which can diffuse blood, for example, absorbent paper sheet. This problem can be solved to some extent by increasing the content of the polymeric absorbent material or the amount of cottony pulp.
However, these enhance the production cost and increase the thickness, the latter resulting in lowering the feeling in use, so that they are not substantially effective solution. In other words, the napkin shown in Fig. 7 has a disadvantage that the whole absorbent layer is not utilized.
The present inventors -think that such a napkin would still exhibit insufficient absorption, particularly poor leak proofness against side leakage, even if the highly absorbent .

~.
~ILZ9~36E~4 polymer functions effectively. That is because a sanitary napkin is significantly deformed by pressure brought about by the application thereof to the crotch to cause side leakage.
That is to say, when a sanitary napkin is applied to the crotch, it is in a deformed (twisted) state as shown in Fig. 11, so that most of leakage occurs from the sides in the central part of the longitudinal direction. More precisely, when pressure due : to the closing of feet or walking is applied to a wet sanitary napkin containing absorbed blood, the napkin is twisted in the central part of the longitudinal direction, so that the distance between the both sides and the blood-absorbing area (the central part of the width direction, when the napkin is accurately worn) is reduced to cause leakage, though -there are still parts wherein no blood is absorbed.
Summary of the Invention In view of the above problems, the inventors have extensively attempted to construct a sanitary napkin which is protected from deformation and twisting in use without lowering ~he feeling and exhibits effectively reduced side leakage by enhancing the fitness of the napkin to the crotch and the pubic region and have accomplished the present invention.
The present invention provides a sanitary napkin com-prisin~ a liquid-permeable surface sheet, a liquid-impermeable leakproof sheet and an absorbent body between the surface sheet and the leakproof sheet. The absorbent body comprises a firs-t absorbent paper sheet, a second absorbent paper sheet and an ~;~9~361~14 absorbent material between these paper~ sheets. The first absorbent paper sheet covers at least a part of the second absorbent paper sheet and the first absorbent paper sheet is bonded to the leakproof sheet at a portion covering the second absorbent paper shee-t.
It is preferable that the absorbent material comprises fluffy pulp and an absorbent polymer It is preferred that the sanitary napkin further comprises means for inhibiting the slipping~off of the napkin.
The sanitary napkin of the invention includes such an embodiment that the absorbent body comprises a first absorbent layer and a second absorbent layer on the first absorbent layer and having a smaller width than the first absorbent layer, the leakproof sheet covers at least the bottom face, both side faces and a part of the top face of the first absorbent layer and a part of the side faces of the second absorbent layer, the surface sheet covers at least a part of the leakproof sheet and the top face of the second absorbent layer and fixation is made between the first absorbent layer and the second absorbent layer, the surface sheet and the leakproof sheet and the leakproof sheet and the first or second absorbent layer.
The absorbent material inserted between the first ~ ~5 absorbent paper sheet and the second absorbent paper sheet ~not normally have a clearly defined shape and may be, for example, cottony pulp, called alsoVfluffy pulp, or an absorbent polymer, or a laminate or mixture thereof.

~ ~9~6~ 65702-267 The sanitary napkin according to the presen-t invention has the -following advantages due to the structure described above.
(1) The whole of the absorbent layer containing the polymeric absorbent material can be effectively utilized independently of whether the amount of menstrual blood to be absorbed is large or small.
(2) In the production of the napkin, the scattering of absorbent layer-constituting materials, w~ich causes contaminatlon, is in-hibited so that the obtained napkin is highly hygienic.(3) The cost is low.
(4) The shift and twist of the absorber can be inhibited.
The present invention will be described in more detail by referring to -the figures.
The napkin shown in Fig. 1 can be produced by piling cottony pulp 4 on -the flrst absorbent paper sheet 21 having a width slightly larger than that of the transverse axis of the final product, spraying the piled cottony pulp 4 with a polymeric absorbent material 5 to fix the material 5 on -the pulp 4 (on the face opposite to the face on which the first absorbent paper has been laid), laying the second absorbent paper sheet 22 on the sprayed pulp, folding the first absorbent paper sheet 21 in such a way that the first absorbent paper sheet 21 wraps round both transverse ends of the second absorbent paper 22 to form an enveloped absorbent layer, covering the bottom and both sides of the absorbent layer with a leakproof sheet 3, bonding a part 8 of ~ the area wrapping round the second absorbent paper sheet 22 of : - 8 -~2~8~

the first absorbent paper sheet 21 to the leakproof sheet 3, enclosing the whole oE the obtained intermediate product with a liquid-permeable surface sheet 1 and fixing a shift-inhibiting tape 7 to the non-use face (i.e., the bottom face in Fig. 1).
The napkin shown in Fig. 2 is characterized by the use of an absorbent paper sheet 21 having a width larger than that of the first absorbent paper sheet 21 used in the napkin shown in Fig. 1 as the first absorbent paper sheet and completely wrapping round the second absorbent paper sheet 22 with the first absorbent paper sheet 21 in such a way that the transverse ends of the first absorbent paper sheet 21 overlap each other. Figs. 3 and 4 show C napkins wherein the first absorbent paper sheet 21 wraps ~ both longitudinal ends of the second absorbent paper sheet 22.
The process for bonding the area wrapping round the second absorbent paper sheet 22 of the first absorbent paper sheet 21 to the leakproof sheet 3 is not particularly limited and may be ; heat-bonding or adhesive-bonding.
The sanitary napkin of the present invention thus produced contains a polymeric absorbent material 5 near the use face. Therefore, even when the amount of menstrual blood is small, the blood rapidly reaches the polymeric absorbent material 5 and is effectively absorbed and kept in the absorbent layer, while when the amount is large, the blood is diffused in the longitudinal direction of the napkin by the second absorbent paper sheet 22 present beneath the polymeric absorbent material 5.
Thus, the whole of the sanitary napkin can effectively contribute to the absorption of blood, so that the napkin is excellent in :~25~8~

absorption and is free from leakage or stickiness. Further, the napkin of the present invention has a structure wherein the whole edge of cottony pulp 4 is wrapped in the first absorbent paper sheet 21 and the second absorbent paper sheet 22, so that the scattering of cottony pulp 4 is inhibited to thereby solve hygienic problems such as contamination of a product.
Furthermore, in the sanitary napkin of the present invention, the first absorbent paper sheet is bonded to the leakproof material sheet, so that the leakproof material sheet is fixed to the absorbent layer. Therefore, the shift and twist of -the absorbent body is remarkably reduced. I'he sanitary napkin of the present invention is also cost advantageous, because it only requires slight enlargement of a part of the absorbent paper sheet of the prior art, but does not necessitate any other constituent member.
Furthermore, the bonding of the first absorbent paper sheet to the leakproof sheet can be carried out by heat-bonding with a heated roll or the like or adhesive-bonding with a very small amount of an adhesive.
As shown before, the invention includes an embodiment ~ 20 in which first and second absorbent layers are used. According to this embodiment, the second absorbent layer is present on top of the first absorbent layer and has a width smaller than that of the first absorbent layer. The liquid-impermeable leakproof material sheet covers at least the bottom face, ~e both side faces and a part of the top face (i.e., the part uncovered by the second absorbent layer) of the first absorbent layer and a part ~ -- 10 --:3~29136~34 of the side faces of the second absorbent layer. The liquid-permeable surface sheet covers the top face of the second absor-bent layer and at leas-t a part of the leakproof sheet. The first absorbent layer is fixed to the second absorbent sheet, the surface sheet is fixed to the leakproof sheet, and the leakproof sheet is fixea to the first or second absorbent layer. They are each so tightly fixed that they do not separate from each other.
The present invention with respect to this embodiment will be further described in more detail by referring to the drawings.
Fig. 8 is a transverse crosssectional view oE a model showing the constituent members of the sanitary napkin according to the present invention. The constituent members can be arranged as follows:
(1) The absorbent body comprises a first absorbent layer 31 as a lower layer and a second absorbent layer 32 having a width smaller than that of the first absorbent layer 31 and, placed on the first absorbent layer 31 near the center of the first absorbent layer.
(2) The first absorbent layer 31 is fixed to the second ab-sorbent layer 32 by certain means, so that they are united by abonding 33 which spreads over at least a part of the interfacial boundary.
(3) The bottom face, the side faces and a par-t of the top face (i.e., the part not covered by the second absorbent layer) of the first absorbent layer 31 and a part of the side faces of the ~ second absorbent layer are covered with a leakproof material sheet 34 and the top face of the second absorbent layer a~d at least a part of the leakproof material sheet are covered with a ~Z9~ 4 liquid-permeable surface sheet 35. Thus, a flap 39 is formed, preferably along each of the longitudinal sides of the first absorbent layer.
(4) In the flap 39, the surface sheet 35 is fixed to the leak-proof sheet 34 by a bonding 36 and the leakproof sheet 34 is fixed to the first absorbent layer 31 by a bonding 37. Each of the bondings may spread over the interfacial boundary.
(5) The sanitary napkin is provided with a shift-inhibiting material 38 (i.e. adhesive) on the non-use face i.e. the bottom face, and a part of the material 38 reaches the leakproof sheet 34 through the surface sheet 35 to form the bonding 36' between the surface sheet and the leakproof sheet.
Each of the constituent members is described below together with effect thereof.
Examples of the material constituting the first absor-bent layer 31 and the second absorbent layer 32 include ordinary absorbent materials such as cottony pulp, absorbent paper and highly absorbent polymer and synthetic fibers such as polyethyl-ene, polypropylene, polyester, acrylic polymer and hot-melt fiber as typified by ES fiber. These materials can be used alone or as a combination thereof and neither the construction nor the mixing method is limited.
The first and second absorbent layers are united by a bonding 33, so that they can not be separated from each other even by pressure brought about by the application of the napkin to the crotch, thus serving to protect the napkin from deformation and twisting.

~L~913689e The difference in width between the first and second absorbent layers is preferably at least 10 mm, more preferably about 30 mm. It is generally effective when the second absorbent layer has a width of 30 to 70 mm. However, the width varies depending upon the object of the application. For example, it is suitable that the width of the second absorbent layer of a napkin of ordinary type is 40 to 50 mm and the width of the second absorbent layer of a napkin for the treatment of light bleeding is 30 to 45 mm, while the width of the second absorbent layer of a napkin for long application or night is 50 to 70 mm. It has been confirmed that the napkin exhibits excellent fitness to the crotch and less deformation even under vivid motion, when the first absorbent layer has a width of 70 to 85 mm and the second absorbent layer hais a width of 40 to 55 mm.
The bonding 36Of the surface sheet 35 to the leakproof sheet 34 and the bonding 37 of the leakproof sheet 34 to the first absorbent layer 31 may be formed in the flap region 39 by either heat sealing or hot melt process. The bonding 36 is preferably present at a distance of 2 to 10 mm, most preferably 3 to 5 mm, from the end of the second absorbent layer 32. If the bonding 36 is too close to the second absorbent layer, the absorbent layer might be influenced by the formation of the bonding, lowering the absorption, touch and appearance. On the contrary, if the bonding 36 is too far from the second absorbent layer, the space between the surface material and the absorbent layer might hinder rapid transfer of the menstrual blood from the surface material to the absorbent layer causing unfavorably side leakage.

~Z9~68~ 5702~267 It is pre-ferred that the bonding 37 is present at a distance of at least 3 mm, preferably about 5 mm, from the end of the leakproof sheet. When it is present at a distance oE about 5 mm from the leakproof sheet, the menstrual blood which has been absorbed and reached the end of the second absorbent layer can be effectively preven-ted from diffusing or spreading in the trans-verse direction to be introduced into the end of the first absor-bent layer 31.
It is preferred that the material to be used for consti-tuting the first absorbent layer has an absorption capacity of atleast 7 g/g (at least 7 g per gram of the material) and an absol-ute absorption capacity of at least 3 g (one side).
The leakproof sheet 3~ to be used in the present inven-tion may be not only an ordinary polymer-laminated waterproof paper obtained by laminating polyethylene or the like on one surface of a sheet of waterproof paper, but also laminated waterproof paper obtained by laminating a resin having a relatively low melting point of 150C or below on one surface of a sheet of waterproof paper or by double-laminating two resins on the both surfaces.
Further, it is preferable that the shift-inhibiting pressure-sensitive adhesive 38, which is present on the non-use surface and is a pressure-sensitive adhesive tape or a hot melt, reaches the back face of the leakproof sheet through the surface ' sheet. In this case, the surface sheet 35 is fixed to the leak-:~ proof sheet 34 by the bonding 36' under the back face of the first 868~

absorbent layer 31. The bonding 36' are preferably strong enough to stand loading of at least 30 g as a whole of the napkin.
As described above, the sanitary napkin according to the present invention is characterized in that it is essentially con-stituted by a main absorbent layer (second absorbent layer) which has a small width and therefore is well fit to the crotch and a flap-forming absorbent layer (first absorbent layer) and that the fixation of the first absorbent layer to the second absorbent layer, that of the surface sheet to the leakproof sheet and that of the leakproof sheet to the first or second absorbent layers are so tight that the fixed components do not separate from each other. Accordingly, the deformation and twisting of the sanitary napkin according to the present invention is less likely to take place than those according to the prior art wherein the constitu-ent members are partially fixed to each other or not united, so that the members must each alone resist the deformation.
Further, according to the present invention the surface sheet is fixed to the absorbent layer. This allows rapid transfer of menstrual blood to the absorber.
Thus, the sanitary napkin according to the present invention exhibits excellent proofness against side leakage and is excellent in fitness without giving feeling as a foreign sub-stance.
The sanitary napkin preferably includes a tape means for inhibiting the slipping-off of the napkin. The tape means is illustrated more in detail below.

9~ 4 Fig. 14(a) through (d) show forms of slip inhibitors provided on the non-use surface of sanitary napkins according to the prior art. Fig. 14(a) shows one of the commonest forms where-in a double-coated adhesive tape (i.e., a tape both faces of which are coated with adhesive) 101 is fixed transversely. Most of the sanitary napkins now commercially available are oE this type, which is called "one transverse tape type". The sanitary napkin of this type has less problems in wearing than other types, but has a disadvantage that the essential requirement of the tape, i.e. the slip-inhibiting effect is poor.
Fig. 14(b) shows another case wherein hot-melt adhesive 102 is applied in a longitudinal area, which is called "one longi-tudinal tape type". Although the napkin of this type is expected to exhibit side slip inhibiting effect better than the "one trans-verse tape type", it does not really highly effective but rather tends to frequently cause slip and uncomfortableness.
Figs. 14(c) and (d) show an arrangement oE slip inhibi-~; tor which has been proposed for enhancing the side slip inhibiting effects. Fig. 14(c) shows a case wherein two double-coated adhes-ive tapes 101 are arranged transversely and Fig. 14(d) shows a case wherein hot-melt adhesive 102 is applied in two areas longi-tudinally. The napkins of the two transverse or longitudinal tape type have a disadvantage which is substantially similar to that of the napkin of the above one longitudinal tape type.
As described above, none of the slip inhibitor means according to the prior art sufficient inhibits the slipping-off (particularly in side directions).

291368~

The inventors studied the form of a sanitary napkin taken when a wearer assumes various postures (such as sitting or walking) and have found that the hatched area 103 of the napkin shown in Fig. 12 is in a bent state in use, so that the arrangement of slip inhibitor in the hatched area reduces the effectiveness oE the slip inhibitor. Accordingly, the slip inhibitor is thought to be effective when it is arranged in the other area 104 wherein the deformation caused by wearing and various postures is slight. Further, if no slip inhibitor is arranged in the area to be touched by a wearer when the napkin is applied to the crotch, i.e., the area near the front end (namely, the dotted area 107 in Fig. 12), the adhesive does not adhere to a wearer's hand, so that the napkin can be easily worn without causing uncomfortableness.
The inventors studied the effectiveness of slip inhibitors arranged in various forms and have found effective slip inhibitors which are arranged on the non-use face such that a line of the front ends is concave. This line may be an actual line when the slip inhibitor is a transversely wide adhesive tape.
20 This line may be an imaginary line drawn by connecting the front ends of the stripes near the front end of the napkin, when the slip inhibitor is a plurality of longitudinal stripes of adhesive or adhesive tapes. The front end here means the end of the napkin which comes to the front when is use.
The slip inhibitors are preferably unevenly arranged in the front part. It is particularly preferred that the line formed by connecting the rear ends of the slip inhibitors near the ~, ; - 17 -868~

rear end of the napkin is convex. Further, it is preferred that the napkin is provided as the slip inhibitor with at least -three longitudinal stripes of adhesive.
A typical example of the transversely wide adhesive tape i5 shown in Fig. 13(c) and typical examples of the longitudinal stripes of adhesivesare shown in Fig. 13 (a), (b) and (c). The concave line or imaginary line is represented by numeral 108.
Although the material of the slip inhibitor is not particularly limited, examples thereof include double-coated adhesive tapes, pressure-sensitive adhesives and hot-melt adhesives.
According to the present inven-tion, the slip inhibitor is generally applied on the non use surface of a sanitary napkin, for instance, by discharging adhesive from a nozzle or by coating a release paper with an adhesive and transferring the adhesive to the non-use surface of a sanitary napkin, though other processes are possible. Further, the concave arrangement of the ends of slip inhibitors near the front end of the napkin can be easily carried out by using nozzles arranged not in a straight line but in zigzags. The preferred width of the slip inhibitor is 3 to 6 mm.
According to the present device, there are no limits with respect to the following factors:
(1) raw materials and production process of the surface sheet, (2) raw materials, amount and necessity of the cottony staple, (3) amount of the cottony pulp, .

~9~6~ 5702-267 (4) kind and content of the polymeric absorbent material, (5) production process and amount of the absorbent paper, (6) kind and characteristics of the polymer-laminated waterproof paper (kind of the laminating resin and whether the resin is applied to the both surface or to either surface), (7) kind, application posi-tion and amount of the shift-inhibiting material, (8) kind, application length and amount of the adhesive, (9) process of the heat-bonding, and the like.
It is particularly advantageous that most of the slip inhibitors are present in the Eront part of the napkin and little present in the area which is most significantly deformed by pressure brought about when the napkin is applied to the crotch, so that the napkin can be effectively bonded to the object by the slip inhibitors and that the slip inhibitors are arranged in a form similar to that of a feather of an arrow as a whole (see Fig. 13(a) and (d)), so that the bonding area spreads widely and effectively. Although such a wide and effective bonding area can be also attained by applying an adhesive rectangularly~ this process necessitates a large amount of an adhesive.
[Examples]
The present invention will be further described in more detail by the following Examples, though it is not limited by them.
Examples 1 to 4 and Comparative Examples 1 to 3 Various napkins were produced by using the constituent members ` which will be described below and state after wearing for 2 hours :' - - \
.~29i~

and hygienic qualities were examined. The results are shown in Table 1.
<Constituent members~
1) Non-woven -fabric (surface sheet):
Olefin non-woven fabric produced by heat-bonding Weight per unit area: 20 g/m2 2) First absorbent paper sheet:
Ordinary paper made of 100% of pulp Weight per unit area: 18 g/m2 3) Second absorbent paper sheet:
Ordinary paper made of 100% of pulp Weight per unit area: 30 g/m2 4) Leakproof material:
A product obtained by laminating a waterproof paper having a weight per unit area of 25 g/m2 and polyethylene (10 ~) 5) Cottony pulp:
NBKP type 6) Polymeric absorbent material:
Polymer of acrylic derivatives (Amount: 0.3 g) It should be understood from the results shown in Table 1 that the napkin of the present invention can be produced without scattering pulp nor polymer and exhibits remarkably reduced shift and twist of the absorbent materia] and therefore has excellent absorption and feeling when worn. That is to say, the napkin is excellent in the state in use and hygienic qualities.

~Z98~8~ 5702-267 Table 1 Structure State after wearing and hygienic of napkin qualities *l_ _ _ Comp. Fig. 5 Ex. 1 good . ~ ~
Comp. Fig. 6 The shift and twist of the absor-Ex. 2 bent material, the separation of the absorbent material from the O
leakproof material and the scatt-_ ering of pulp were observed.
Comp.
Ex. 3 Fig. 7 The shift of the absorben-t mater-ial was not observed, bu-t the twist of the absorbent material, the separation of the absorbent material from the leakproof mater-ial and the scattering of pulp were observed.
. ._~ _ . . _ Ex. 1 Fig. 1 Neither the shi~t nor -the twist of the absorbent material, the separ-ation of the absorbent material, from the leakproof material nor ~_i the scattering of pulp was observ-ed.
_ . _ _. _ ~ Ex. 2 Fig. 2 do O
. . _ _ . . __ _ Ex. 3 Fig. 3 do O
. .. . . _ Ex. 4 Fig. 4 do ~
_ , _ f~
Note) *l ~J : Neither pulp nor polymer scattered from the absorbent body nor from the napkin at all : Pulp and polymer slightly scattered from the absorbent body : Pulp and polymer slightly scattered from the absorbent body and from the napkin Example 5 A sanitary napkin of Fig. 9 shows the embodiment of the invention in which the absorbent body contains the first absorbent layer and the second absorbent layer. In the drawing, (a) is a ~' plan view and (b) is a cross-sectional view taken along X-X'. In Fig. 9, the first absorbent layer is made of a stack of absorbent paper sheets 40 and the second absorbent layer is made of cottony pulp 41 containing a highly absorbent polymer 42 and these absorbent layers are covered with an absorbent paper sheet 40', while the first absorbent layer is fixed to the absorbent paper sheet 40' by a bonding 33. Rayon staple cotton 43 is laid on the above absorbent layers and the bottom and the sides of the resulting laminate is covered with leakproof material 34 and wrapped in a surface material 35. Further, the non-use surface is provided with a pressure-sensitive adhesive tape 3~. The surface material 35 is fixed to the leakproof material 34 by bondings 36, 36', while the leakproof material 34 is fixed to the absorbent paper 40' by a bonding 37.
Fig. 10 is a transverse crosssectional view of another example of the napkin according to the present invention.
Example 6 A plurality of linear slip inhibitors 105 were applied - on the non-use surface of a sanitary napkin in such a way that the line formed by connecting the ends of the slip inhibitors nearer the front end of the napkin was concave to obtain a sanitary napkin provided with slip inhibitors as shown in Fig. 13(a).
Example 7 A plurality of slip inhibitors 105 were applied on a sanitary napkin in such a way that they are continuously arranged over the front part and the back part of the napkin to obtain a sanitary napkin as shown in Fig. 13(b).

~ ~g 86 ~ ~ 5702-267 Example 8 The front part of an adhesive tape used in the napkin of the above one transverse tape type was cut concavely and the back part thereof was cut convexly. The resulting cut kape was applied on a sanitary napkin to obtain a sanitary napkin as shown in Fig.
13(c).
Example 9 A part of the slip inhibitors was removed from a sanitary napkin as shown in Fig. 13(a). A release paper 106 was laid on the surface of the resulting napkin so as to cover the top surface of the remaining slip inhibi-tors with the release paper (the release paper may have any form, as far as the slip inhibitors can be completely covered with it, and particularly, easily strippable ones are preferred). Thus a sanitary napkin as shown in Fig. 13(d) was obtained.
The obtained four napkins were examined by practical i wearing. They exhibited reduced slip and twist without causing the bonding of adhesive to each other. Further, it was evaluated to be easily wearable.

Claims

1. A sanitary napkin which comprises a liquid-permeable surface sheet, a liquid-impermeable leakproof sheet and an absor-bent body between the surface sheet and the leakproof sheet, the absorbent body comprising a first absorbent paper sheet, a second absorbent paper sheet and an absorbent material between the first and second paper sheets, wherein the first absorbent paper sheet covers at least a part of the second absorbent paper sheet and the first absorbent paper sheet is fixed at a portion thereof covering the second absorbent paper sheet to the leakproof sheet.

2. A sanitary napkin as claimed in claim 1, in which the absorbent material does not itself have a clearly defined shape and is a laminate or mixture containing fluffy pulp and an absor-bent polymer.

3. A sanitary napkin as claimed in claim 1, which further comprises means for inhibiting a slipping-off of the napkin.

4. A sanitary napkin as claimed in claim 1, in which:
the absorbent body comprises a first absorbent layer and a second absorbent layer, the second absorbent layer being placed on the first absorbent layer and having a smaller width than the first absorbent layer;
the leakproof sheet covers at least the bottom face, both side faces and the part of the top face of the first absorbent layer uncovered by the second absorbent layer and a part of the side faces of the second absorbent layer;
the surface sheet covers the top face of the second absorbent layer and at least a part of the leakproof sheet(and-light fixation is made between the first absorbent layer and the second absorbent layer, between the surface sheet and the leakproof sheet, and between the leakproof sheet and the first or second absorbent layer such that the fixed components do not separate from each other.

5. A sanitary napkin which comprises:
a liquid-permeable surface sheet, a liquid-impermeable leakproof sheet, and an absorbent body of generally a thick rectangle or oval shape capable of absorbing menstrual blood and comprising:
an absorbent material composed of a mixture of laminate of fluffy pulp and a highly blood absorbent polymer between a first absorbent paper sheet and a second absorbent paper sheet, the second absorbent paper sheet covering substantially the whole of the bottom face of the absorbent material and the first absorbent paper sheet covering the top and the side faces of the absorbent material as well as at least the outer portions of the second absorbent paper sheet, thus the first and second absorbent paper sheets together enveloping the absorbent material, the liquid-impermeable leakproof sheet covering the bottom face and optionally the side faces of the absorbent layer, the first absorbent paper sheet being fixed at a portion thereof covering the second absorbent paper sheet, to the leak-proof sheet, and the liquid-permeable surface sheet covering at least the top face of the absorbent layer.

6. A sanitary napkin as claimed in claim 5, in which the absorbent layer comprises a fluffy pulp layer on the bottom face of which the highly blood absorbent polymer is fixed.

7. A sanitary napkin as claimed in claim 6, which further comprises on the bottom face of the napkin, a tape means for inhibiting a slipping-off of the napkin from the skin of a wearer.

8. A sanitary napkin as claimed in claim 5, 6 or 7, in which the liquid-permeable surface sheet encloses substantially entirely the absorbent layer and the liquid-impermeable leakproof sheet.

9. A sanitary napkin as claimed in claim 5, 6 or 7, in which the liquid-permeable surface sheet is made of non-woven fabric and polymer-laminated waterproof paper.

10. A sanitary napkin as claimed in claim 4, in which the second absorbent layer has a width of 30 to 70 mm which is at least 10 mm smaller than the first absorbent layer.

11. A sanitary napkin as claimed in claim 4, in which the first absorbent layer has a width of 70 to 85 mm and the second absorbent layer has a width of 40 to 55 mm which is about 30 mm smaller than the first absorbent layer.

12. A sanitary napkin as claimed in claim 10, in which the second absorbent layer is placed near the center of the first absorbent layer, thus forming a flap region along each of the longitudinal sides of the first absorbent layer.

13. A sanitary napkin as claimed in claim 12, in which the liquid-permeable surface sheet and liquid-impermeable leakproof sheet are fixed to the first absorbent layer in the flap region by heat sealing or hot melt process.

14. A sanitary napkin as claimed in claim 3 or 7, wherein:
the slipping-off inhibiting means comprises at least three stripes of an adhesive arranged in a longitudinal direction on a non-use face of the napkin such that an imaginary line drawn by connecting front ends of the stripes is generally concave.