Elongated absorbent article

Disclosed is an elongated absorbent article including: rear inner compressed grooves disposed in a rear half of the absorbent article and extending symmetrically about a longitudinal centerline of the absorbent article, defining therebetween a rear central region; and a rear connecting compressed groove connecting rear ends of the rear inner compressed grooves, defining a rear end of the rear central region. A liquid absorbent layer is recessed in the rear central region from the side of the garment surface toward the skin surface to have a backside compressed portion extending along the longitudinal centerline. The backside compressed portion has a rear end positioned forward of the rear connecting compressed groove.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an absorbent article suitable for absorbing menstrual blood and so on discharged from a woman's genital organ, more particularly, relates to an elongated absorbent article intended to cover the wearer's body from a vaginal opening to buttocks.

2. Description of the Related Art

Absorbent articles intended to absorb menstrual blood discharged from a woman's genital organ are typically constructed to include a liquid-permeable topsheet appearing on its skin surface, a liquid-impermeable backsheet appearing on its garment surface and a liquid absorbent layer disposed between the topsheet and the backsheet, and generally, they are worn with the backsheet adhered to an inner side of a groin piece of an undergarment through a pressure-sensitive adhesive layer.

In such an absorbent article, the function of certainly collecting menstrual blood applied to the skin surface is required so as to prevent lateral leakage of liquid and rearward leakage of liquid from the absorbent article.

Particularly in an absorbent article that is intended to be worn by a woman during menstruation while sleeping, required is not only prevention of lateral leakage of menstrual blood from the absorbent article but certain absorption of menstrual blood trying to flow along the wearer's body toward the anus and the cleft of the buttocks or trying to flow along the skin surface of the absorbent article rearwardly without causing any leakage. Accordingly, such an absorbent article for nighttime use is elongated more than absorbent articles for daytime use so that its skin surface can cover a large area from a mons pubis which is anterior to the vaginal opening to the buttocks which is posterior to the anus.

In sanitary napkins of this kind, there have been known ones whose skin surface can easily fit in the woman's crotch, wherein compressed grooves are formed in the liquid absorbent layer so as to function as flexible hinges.

Japanese Unexamined Patent Publication No. 10-328233 (Patent Publication 1) discloses an elongated sanitary napkin whose rear portion can cover the buttocks of a wearer. In a front portion of this sanitary napkin, a pair of longitudinally extending topside grooves is formed in the skin surface; in a rear portion thereof, a longitudinally extending rear groove is formed in the garment surface. The topside grooves are spaced longitudinally apart from the rear groove so as not to overlap as viewed from a lateral direction. In this sanitary napkin, since the topside grooves in the front portion can function as flexible hinges, a central portion positioned between the topside grooves can be easily deformed in an arch-like state toward the wearer's body so as to come into close contact with the excretory part, and in addition, since the napkin can be easily deformed in the rear portion to bulge toward the wearer's body along the rear groove, the bulging portion can easily fit in the cleft of the buttocks.

On the other hand, Japanese Unexamined Utility-Model Publication No. 3-33622 (Patent Publication 2) discloses a sanitary napkin, in which a pair of longitudinally extending first compressed grooves is formed in the skin surface of the napkin, while a longitudinally extending second compressed groove is formed in the garment surface of the napkin at an intermediate position between the first compressed grooves in pair. This sanitary napkin can be easily deformed into a W-shaped cross section such that the central portion of the napkin is deformed at the second compressed groove to bulge toward the wearer's skin while both side portions of the napkin are deformed at the first compressed grooves to bulge toward the garment, whereby the central portion of the napkin comes into close contact with the excretory part of the wearer's body.

In the sanitary napkin disclosed in Patent Publication 1, the rear groove is formed in its rear portion so that the portion having the rear groove can fit in the cleft of the buttocks. However, since the rear portion is flat except for the rear groove, if the rear groove is pressed against the cleft of the buttocks, such as by elastic members provided centrally of a back body of sanitary shorts, portions at both sides of the rear groove tend to deform away from the buttocks due to a reaction force to the pressure given to the rear groove. Accordingly, a space is easily left between the surface of the buttocks and the rear portion of the sanitary napkin.

In the sanitary napkin disclosed in Patent Publication 2, on the other hand, the sanitary napkin can be easily deformed into a W-shaped cross section when subjected to a lateral pressure from the thighs, so that the central portion of the skin surface can easily come into close contact with the vaginal opening. However, if the construction disclosed in Patent Publication 2 is adopted for a rear portion of a sanitary napkin that is intended to contact the buttocks, the rear portion of the sanitary napkin cannot closely conform to the curved surface of the buttocks. More specifically, since the buttocks have a cleft posterior to the anus and are three-dimensionally outwardly curved at both sides of the cleft, the rear portion of the sanitary napkin that is deformed in a W-shaped cross section hardly conforms to the three-dimensionally outwardly curved surface. Therefore, leaving a space between the surface of the buttocks and the rear portion of the sanitary napkin cannot be prevented.

SUMMARY OF THE INVENTION

The present invention has been worked out in view of the shortcomings in the prior art set forth above. It is therefore an object of the present invention to provide an absorbent article whose rear portion can easily fit in the cleft of the buttocks and can be easily deformed in portions other than the portion intended to fit in the cleft to have a three-dimensionally concavely curved surface in accordance with the contour of the buttocks.

According to the present invention, there is provided an elongated absorbent article comprising: a liquid-permeable topsheet appearing on a skin surface; a backsheet appearing on a garment surface; and a liquid absorbent layer disposed between the topsheet and the backsheet, the absorbent article having compressed groove where the skin surface is recessed toward the garment surface with the liquid absorbent layer compressed together with the topsheet, whereinthe compressed groove includes: rear inner compressed grooves disposed in a rear half of the absorbent article and extending symmetrically about a longitudinal centerline of the absorbent article, defining therebetween a rear central region; and a rear connecting compressed groove connecting rear ends of the rear inner compressed grooves, defining a rear end of the rear central region, whereinthe liquid absorbent layer is recessed in the rear central region from the side of the garment surface toward the skin surface to have a backside compressed portion extending along the longitudinal centerline, the backside compressed portion having a rear end positioned forward of the rear connecting compressed groove.

In this absorbent article, when the rear central region is pressed against the cleft of the buttocks by a tightening force of an undergarment, the rear central region having the backside compressed portion can be deformed to fit in the cleft of the buttocks. Since the rear central region having the backside compressed portion is surrounded by the rear inner compressed grooves and the rear connecting compressed groove, portions outside the rear central region that is deformed to bulge toward the cleft of the buttocks can be easily curved concavely three-dimensionally with starting point at the rear inner compressed grooves and the rear connecting compressed groove. Thus, while the rear central region can enter the cleft of the buttocks, the surrounding portions can conform to the curved surface of the buttocks, thereby improving contact between the buttocks and the absorbent article.

In the present invention, the rear inner compressed grooves may be formed to gradually decrease a separation distance therebetween rearwardly of the absorbent article.

With this construction, the rear central region can easily enter the cleft of the buttocks.

In the present invention, rear outer compressed grooves may be disposed laterally outside the rear inner compressed grooves to extend longitudinally of the absorbent article.

With this construction, portions outside the rear central region can be easily curved concavely three-dimensionally.

Preferably, the rear outer compressed grooves are connected with each other at a position spaced rearwardly apart from the rear connecting compressed groove.

With this construction, since the compressed grooves are doubled in a rear portion of the absorbent article, the absorbent article can be easily curved concavely three-dimensionally in the rear portion.

In the present invention, density of the liquid absorbent layer may be higher in regions positioned between the rear inner compressed grooves and the rear outer compressed grooves than in the rear central region.

With the density of the liquid absorbent layer thus increased outside the rear inner compressed grooves, the portions outside the rear central region can be kept in a three-dimensionally concavely curved state, preventing occurrence of distortion or twist due to a pressure from the wearer's body.

The present invention may also be constructed such that the compressed groove further includes: front inner compressed grooves extending forwardly from the rear inner compressed grooves without interruption; and front outer compressed grooves disposed laterally outside the front inner compressed grooves to extend longitudinally of the absorbent article, whereininflected portions are provided at boundaries between the rear inner compressed grooves and the front inner compressed grooves to increase a separation distance between laterally opposed compressed grooves, the rear outer compressed grooves being spaced apart from the front outer compressed grooves in portions laterally outside the inflected portions.

In the absorbent article thus constructed, the widened portion positioned between the inflected portions intensively receives a pressure from four directions due to the presence of the front outer compressed grooves and the rear outer compressed grooves positioned forward and rearward thereof, the widened portion positioned between the inflected portions can be bulged toward the perineum of a wearer to come into close contact with the perineum. Leakage of menstrual blood from the rear end of the absorbent article toward the buttocks can be effectively prevented by such close contact with the perineum, the fit of the rear central region into the cleft of the buttocks, and the deformation into a three-dimensionally concavely curved state.

In the present invention, elastically extensible members for exerting an elastic shrinkage force on the skin surface in the longitudinal direction may be disposed so that rear action ends of the elastically extensible members are positioned forward of or in the vicinities of front ends of the rear outer compressed grooves.

Since front and rear portions of the absorbent article are attracted to each other with such elastically extensible members, the absorbent article can be easily recessed to conform to the contour of the wearer's body. Here, since the rear outer compressed grooves are positioned rearward of the action ends of the elastically extensible members, the elastic shrinkage force of the elastically extensible members does not act on the rear inner compressed grooves and the rear outer compressed grooves disposed around the rear central region, so that the portions outside the rear central region can be certainly kept in a concavely curved state.

In the present invention, it is also preferred that the backsheet is bonded to the backside compressed portion of the liquid absorbent layer so that the backsheet fits in the recess of the backside compressed portion.

With the backsheet fitting in the recess of the backside compressed portion, the material of the backsheet functions to reinforce the shape of the backside compressed portion, so that the liquid absorbent layer can be certainly maintained in a bulging state along the backside compressed portion.

Also preferably, a pressure-sensitive adhesive layer is disposed on an exterior surface of the backsheet in a region elongated longitudinally of the absorbent article to cover the backside compressed portion.

With this construction, since the backsheet can be firmly fixed to an undergarment within the elongated region covering the backside compressed portion, the backside compressed portion can be prevented from being displaced from the center of the undergarment, so that the portion including the backside compressed portion can be certainly pressed into the cleft of the buttocks by a tightening force of the undergarment.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In the present invention, the absorbent article refers to a sanitary napkin whose primary object is to absorb menstrual blood discharged from the vaginal opening of a woman. It should be noted that the absorbent article has two major surfaces: of which one surface intended to be worn toward the wearer's crotch is referred to as “skin surface”, while the other surface is referred to as “garment surface” regardless of whether a garment is worn outside the absorbent article or not.

As used herein, the term “longitudinal centerline” refers to a line which extends longitudinally to divide the absorbent article laterally in two. On the other hand, the term “lateral reference line” does not necessarily refer to a line which extends laterally to divide the absorbent article longitudinally in two, but refers to a line which extends laterally to cross a longitudinal center of a portion intended to be brought into contact with the vaginal opening during wear.

The compressed grooves and the backside compressed portion may be formed such that a recess is extended in the shape of a continuous line or such that discrete compressed portions are arranged in a row. The rear central region refers to a region that is intended to face a portion of a wearer's body positioned posterior to the vaginal opening and including the anus and the cleft of the buttocks, while a front central region refers to a region that is intended to contact the vaginal opening. The boundary between the front central region and the rear central region is intended to face the perineum positioned between the vaginal opening and the anus.

FIGS. 1 to 3are top plan views showing a sanitary napkin1as an absorbent article according to one embodiment of the present invention, wherein the skin surface faces upward. Although showing the same sanitary napkin1,FIGS. 1 to 3are prepared as different drawings for convenience of explanation of individual components.FIG. 1mainly shows a pattern of compressed groove,FIG. 2shows a configuration of a topsheet, andFIG. 3shows a backside compressed portion and an arrangement of pressure-sensitive adhesive layers.

FIG. 4is a sectional view taken along line IV—IV (lateral reference line), in which the sanitary napkin1is attached to a groin piece of an undergarment, andFIG. 5is a half sectional view taken along line V—V, showing a rear portion of the sanitary napkin1.

The sanitary napkin1ofFIGS. 1 to 3is an elongated sanitary napkin that is suitable for nighttime use by a woman during menstruation, wherein the entire length in the longitudinal direction is from about 200 to 450 mm.

The sanitary napkin1has longitudinally extending right and left side edges1aand1bthat are laterally spaced an equal distance apart from a longitudinal centerline Oy—Oy and outwardly curved front and rear end edges1cand1dthat are longitudinally spaced apart from a lateral reference line Ox—Ox. The distance from the lateral reference line Ox—Ox to the rear end edge1dis larger than the distance from the lateral reference line Ox—Ox to the front end edge1c.

Within a range having a given length in the longitudinal direction and containing the lateral reference line Ox—Ox, the right and left side edges1aand1bproject laterally outwardly, thereby providing wings1A and1A. Rearward of the wings1A and1A, furthermore, the right and left side edges1aand1bare curved to gradually rearwardly increase the lateral separation distance therebetween, thereby providing rear flaps1B and1B.

As shown in the sectional view ofFIG. 4, the sanitary napkin1comprises a liquid-impermeable backsheet2appearing on the garment surface and a liquid-permeable topsheet3appearing on the skin surface. A liquid absorbent layer4is disposed between the backsheet2and the topsheet3, and a second layer5is disposed between the topsheet3and the liquid absorbent layer4. As indicated by a dotted line inFIG. 1, the liquid absorbent layer4extends over a large area from a position just inside the front end edge1cto a position just inside the rear end edge1d, but for the wings1A,1A and the rear flaps1B,1B.

In the sanitary napkin1, compressed groove10is formed in the skin surface by locally pressing and heating at least the topsheet3and the liquid absorbent layer4. More specifically, the compressed groove10is formed by embossing with a heating roller. The compressed groove10may be formed such that after the liquid absorbent layer4is stacked on the topsheet3, a smooth surface roller is applied to an exterior surface of the liquid absorbent layer4while a heating roller with projections arranged in a pattern for embossing is applied to a surface of the topsheet3for pressing and heating.

The compressed groove10has high-density compressed portions10a, in which the liquid absorbent layer4and the topsheet3are pressed until they get almost filmy, and medium-density compressed portions10b, in which although doesn't get filmy, the liquid absorbent layer4is of a higher density than in portions other than the compressed groove10. The high-density compressed portions10aand the medium-density compressed portions10balternate with each other to provide continuously recessed grooves where the skin surface of the sanitary napkin1is recessed toward the side of the backsheet2.

As shown inFIG. 1, the compressed groove10has several distinct compressed grooves indicated by numerals11–17.

Longitudinally extending front inner compressed grooves11A and11A are disposed symmetrically about the longitudinal centerline Oy—Oy. The front inner compressed grooves11A and11A are curved toward the longitudinal centerline Oy—Oy so that separation distance therebetween is minimum at the lateral reference line Ox—Ox. As the front inner compressed grooves11A and11A extend rearwardly (toward the rear end edge1d) from the lateral reference line Ox—Ox, the separation distance therebetween gradually increases. Rearward of the front inner compressed grooves11A and11A, on the other hand, there are disposed rear inner compressed grooves11D and11D whose separation distance gradually decreases rearwardly. The front inner compressed grooves11A and11A are connected to the rear inner compressed grooves11D and11D through inflected portions11B and11B that are also compressed grooves. The separation distance between the inflected portions11B and11B becomes larger than those between the compressed grooves positioned forward and rearward thereof.

Front ends of the front inner compressed grooves11A and11A are connected to each other through a front connecting compressed groove12. The front connecting compressed groove12is curved toward the front end edge1c. From boundaries between the front inner compressed grooves11A and11A and the front connecting compressed groove12, extension compressed grooves13and13are further extended toward the front end edge1c. The extension compressed grooves13and13are disposed symmetrically about the longitudinal centerline Oy—Oy.

Rear ends of the rear inner compressed grooves11D and11D are connected to each other through a rear connecting compressed groove14. The rear connecting compressed groove14is curved toward the rear end edge1d.

Thus, the front inner compressed grooves11A and11A, the inflected portions11B and11B, the rear inner compressed grooves11D and11D, the front connecting compressed groove12, the extension compressed grooves13and13and the rear connecting compressed groove14are mutually connected. In addition, a given area of the skin surface of the sanitary napkin1is surrounded by the front inner compressed grooves11A and11A, the rear inner compressed grooves11D and11D, the front connecting compressed groove12and the rear connecting compressed groove14, and this surrounded area is referred to as central region20. The central region20is of an elongated shape symmetrical about the longitudinal centerline Oy—Oy, wherein a portion forward of the lateral reference line Ox—Ox is shorter than a portion rearward of the lateral reference line Ox—Ox.

The central region20includes a front central region20A and a rear central region20D.FIG. 8shows a state where the sanitary napkin1is applied to the woman's crotch, wherein the front central region20A is in contact with the vaginal opening (N), while the rear central region20D is in contact with a portion including the anus (P) and the cleft (Q) of the buttocks. It should be noted that the central region20is widened at a portion between the inflected portions11B and11B.

In the embodiment shown inFIGS. 1 to 3, the front central region20A is positioned forward of a straight line20E connecting the inflected portions11B and11B and the rear central region20D is positioned rearward of the straight line20E. It should be noted that the widened portion between the inflected portions11B and11B is indicated by20B and the widened portion20B overlaps with both the front central region20A and the rear central region20D.

Laterally outside the front inner compressed grooves11A and11A, there are disposed front outer compressed grooves15and15. The front outer compressed grooves15and15are within a range having a given length forwardly and rearwardly from the lateral reference line Ox—Ox. The front outer compressed grooves15and15are curved similarly to the front inner compressed grooves11A and11A.

Laterally outside the rear inner compressed grooves11D and11D, there are disposed rear outer compressed grooves16and16. The rear outer compressed grooves16and16are inclined to gradually decrease separation distance therebetween toward the rear end edge1d, and the right and left rear outer compressed grooves16and16are connected to each other through an outer rear connecting compressed groove17. The rear outer compressed grooves16and16and the outer rear connecting compressed groove17are continuously formed, wherein the outer rear connecting compressed groove17is curved toward the rear end edge1d.

Laterally outside the widened portion20B defined between the inflected portions11B and11B, the rear ends of the front outer compressed grooves15,15are separated from the front ends16D,16D of the rear outer compressed grooves16,16. Laterally outside the inflected portions11B and11B, therefore, there are provided regions where both the front outer compressed grooves15,15and the rear outer compressed grooves16,16are absent. The distance between the rear ends of the front outer compressed grooves15,15and the front ends16D,16D of the rear outer compressed grooves16,16in the longitudinal direction is about 20 to 60 mm.

In the rear central region20D, as shown inFIGS. 3,5and7, the liquid absorbent layer4is recessed from the side of the garment surface toward the skin surface to have a backside compressed portion18. The backside compressed portion18is formed by compressing the liquid absorbent layer4from the side of the garment surface and extended along the longitudinal centerline Oy—Oy. The backside compressed portion18may be a linear groove, or a row of dot-like compressed portions intermittently arranged in the longitudinal direction, or a row of short linear compressed portions intermittently arranged in the longitudinal direction. As shown inFIG. 3, the backside compressed portion18has a front end18athat is positioned rearward of the straight line20E and a rear end18bthat is positioned forward of the rear connecting compressed groove14.

Along the backside compressed portion18, the liquid absorbent layer4is bonded and fixed to the backsheet2through a hot-melt adhesive or the like. Alternatively, the liquid absorbent layer4may be thermally bonded to the backsheet2. Thus, the backsheet2fits in the recess of the backside compressed portion18.

As shown inFIG. 2, the second layer5is given the shape of a strip elongated to traverse the central region20in the longitudinal direction, wherein right and left side edges5a,5aare spaced inwardly apart from the front inner compressed grooves11A,11A and the rear inner compressed grooves11D,11D. Here, the front end of the second layer5reaches the front end edge1cof the sanitary napkin1, while the rear end reached the rear end edge1d. Accordingly, the topsheet3, the second layer5and the liquid absorbent layer4are compressed together at the front connecting compressed groove12, the rear connecting compressed groove14and the outer rear connecting compressed groove17. At least in the front central region20A of the central region and between the second layer5and the liquid absorbent layer4, moreover, there may be provided a liquid acquisition layer, that is formed of a water absorbent sheet such as air-laid nonwoven fabric (air-laid pulp) obtained by bonding hydrophilic fibers such as pulp and synthetic fibers together with a binder into the form of a sheet.

In the front central region20A, there are regularly arranged a large number of liquid passage holes25. The liquid passage holes25are circular, but may be otherwise shaped, such as elliptical or slit-shaped. Each liquid passage hole25has an opening area of 0.2 to 8 mm2, and in case of circle, it has a diameter of 0.5 to 3.2 mm. The center-to-center distance between adjacent liquid passage holes25is 1.5 to 8 mm. The liquid passage holes25are formed to pass through the topsheet3and reach the second layer5, and preferably, the liquid passage holes25are formed to pass through both the topsheet3and the second layer5, as shown inFIG. 4. The liquid passage holes25are evenly distributed over the front central region20A positioned between the straight line20E connecting the inflected portions11B,11B and the front connecting compressed groove12.

In the rear central region20D, as shown inFIGS. 2 and 5, the topsheet3is shaped to have a corrugated portion28. Within the corrugated portion28, more specifically, the topsheet3is given a wavy cross-section so that ribs and grooves extend parallel with the longitudinal direction of the article and alternate with each other in the lateral direction of the article. The corrugated portion28covers the entire rear central region20D that is surrounded by the rear inner compressed grooves11D,11D, the straight line20E and the rear connecting compressed groove14.

Since the topsheet3thus provided with the corrugated portion28is extensible in the lateral direction, when the rear central region20D is deformed to bulge toward the wearer's body as shown inFIG. 7, the topsheet3is allowed to freely extend in the lateral direction.

The topsheet3comprises heat-fusible, thermoplastic fibers, and the second layer5also comprises heat-fusible, thermoplastic fibers. Here, the topsheet3and the second layer5should not be construed as limited to a sheet/layer formed only of such thermoplastic fibers, but may contain other fibers that are not heat-fusible, such as natural fibers and regenerated cellulose fibers, in addition to the thermoplastic fibers.

The liquid passage holes25can be formed using heated needles or pins. More specifically, the liquid passage holes25can be formed in such a way that after the topsheet3and the second layer5are stacked, the needles or pins are inserted in a direction from the topsheet3to the second layer5and then drawn out. At this time, the thermoplastic fibers contained in the topsheet3and the thermoplastic fibers contained in the second layer5are fusion-bonded together along inner surfaces of the liquid passage holes25and therearound. This results in that the opening shape of the liquid passage hole25becomes stable and that the portion around the opening of the liquid passage hole25is reinforced with the second layer5. In addition, since the topsheet3and the second layer5are thermally fusion-bonded together, there is no need for bonding the topsheet3and the second layer5together through an adhesive, precluding the possibility that the adhesive will interfere with liquid permeation.

The corrugated portion28is formed by heat-embossing only the topsheet3, for example, such that an embossing roller having ribs of a height of 1.8 mm arranged at a pitch of 1.8 mm and another embossing roller having grooves in which the ribs are to be mated are heated to 100 to 125 degrees centigrade and then the topsheet3is held between these rollers to form ribs and grooves. Since the topsheet3comprises the thermoplastic fibers, it tends to maintain such a corrugated configuration when no external force is exerted thereon, which makes the topsheet3extensible in the lateral direction.

The topsheet3may be through-air bonded nonwoven fabric. For the through-air bonded nonwoven fabric, sheath/core bicomponent synthetic fibers, of which the core component is polyethylene terephthalate (PET) containing titanium oxide and the sheath component is polyethylene (PE), are bonded together by means of hot air to have a basis weight of about 15 to 60 g/m2. It should be noted that some of the bicomponent synthetic fibers used for the topsheet3are coated with a hydrophilic lubricant while the rest are coated with a water-repellent lubricant and they are blended with each other, wherein the blending ratio of the fibers coated with the water-repellent lubricant is preferably 10 to 30% by weight. With the fibers coated with the water-repellent lubricant uniformly contained in the topsheet3to have a blending ratio within the above-mentioned range, menstrual blood given to the topsheet3can be prevented from being excessively diffused in the topsheet3, so that menstrual blood can be introduced into the liquid absorbent layer4mainly through the liquid passage holes25.

It should be noted that also in regions other than the liquid passage holes25, menstrual blood can permeate through the topsheet3into the second layer5. In order to provide the topsheet3with such permeability to liquid, the density is preferably equal to or less than 0.12 g/cm3, wherein the lower limit is about 0.025 g/cm3.

The second layer5may be through-air bonded nonwoven fabric comprising eccentric sheath/core bicomponent synthetic fibers, of which the core component is polypropylene (PP) and the sheath component is polyethylene (PE). In the through-air bonded nonwoven fabric for the second layer5, all the fibers are coated with a hydrophilic lubricant. That is, fibers coated with a water-repellent lubricant are not contained. In the present embodiment, the second layer5is formed by stacking a plurality of layers of the through-air bonded nonwoven fabric, such as by folding a single through-air bonded nonwoven fabric in three-ply construction. The single through-air bonded nonwoven fabric has a basis weight of about 15 to 50 g/m2, so that the second layer5has a basis weight of about 35 to 150 g/m2, preferably 50 to 100 g/m2.

With the basis weight of the second layer5made higher than the basis weight of the topsheet3, the topsheet3of a low basis weight and a low density can be reinforced, thereby preventing occurrence of extremely large wrinkles in the topsheet3and occurrence of breakage from the liquid passage holes25.

For example, the topsheet3may comprise fibers having a fineness of 2.2 dtex and the second layer5may comprise fibers having a fineness of 4.4 dtex so that the fiber density of the second layer5is lower than the fiber density of the topsheet3. The fiber density of the second layer5is 0.08 to 0.016 g/cm3.

If the second layer5is formed of fibers with high fineness, the second layer5can be provided with a three-dimensional fiber network structure to leave a great number of large voids therein. Accordingly, menstrual blood having passed through the topsheet3can also pass through the voids under gravitation, so that a large amount of menstrual blood given to the napkin at a time can be rapidly introduced into the liquid absorbent layer4.

Alternatively, the topsheet3and the second layer5may be nonwoven fabric other than the through-air bonded nonwoven fabric. For example, the topsheet3may be spunlaced nonwoven fabric comprising regenerated cellulose fibers, heat-fusible thermoplastic fibers and optionally also pulp; the second layer5may be air-laid nonwoven fabric (air-laid pulp), in which pulp and thermoplastic fibers are accumulated in air, bonded together with a binder, and pressed between heating rollers.

The liquid absorbent layer4may be formed by adding synthetic absorbent polymer such as polyacrylate, polyacrylamide and maleic anhydride or natural absorbent polymer such as starch and cellulose to an aggregate of pulp such as ground pulp, mercerized pulp or crosslinked pulp, wherein the pulp and the synthetic absorbent polymer or the like are wrapped in hydrophilic tissue paper.

The backsheet2is a liquid-impermeable, breathable sheet such as a polyethylene (PE) or polypropylene (PP) film formed with minute pores. The minute pores may be appropriately distributed over the film for improving breathability such as by adding inorganic filler such as CaCO3and BaSO4to the plastic sheet, followed by drawing. The film may have a thickness of about 15 to 50 μm.

The second layer5and the liquid absorbent layer4are bonded together through a hot-melt adhesive that is partially applied so as not to interfere with liquid permeation. The liquid absorbent layer4and the backsheet2are also bonded together through a hot-melt adhesive. Therefore, the backsheet2can enter the recess of the backside compressed portion18, as set forth above.

In a manufacturing process of the sanitary napkin1, after the topsheet3in which the corrugated portion28has been already formed and the second layer5are stacked, the liquid passage holes25are formed therein, and then, the liquid absorbent layer4and the second layer5are bonded together, followed by forming the compressed groove10and the backside compressed portion18. Subsequently, the backsheet2is bonded to a surface of the liquid absorbent layer4. Here, it is also possible to thermally fusion-bond the liquid absorbent layer4to the backsheet2in such a manner that after the backsheet2is thus bonded to the surface of the liquid absorbent layer4, the backsheet2and the liquid absorbent layer4are heated together under pressure at the backside compressed portion18.

The basis weight of the liquid absorbent layer4becomes largest at the central region20. The basis weight at front side regions21,21located between the front inner compressed grooves11A,11A and the front outer compressed grooves15,15, the basis weight at rear side regions24,24located between the rear inner compressed grooves11D,11D and the rear outer compressed grooves16,16and the basis weight at a rear region26located between the rear connecting compressed groove14and the outer rear connecting compressed groove17are all lower than the basis weight at the central region20. The basis weight of the liquid absorbent layer4at the other portions is equal to or slightly lower than those at the front side regions21,21, the rear side regions24,24and the rear region26.

The basis weight of the liquid absorbent layer4at the central region20is preferably 400 to 1200 g/m2, more preferably 500 to 1000 g/m2. The basis weight at the front side regions21,21, the basis weight at the rear side regions24,24and the basis weight at the rear region26are preferably 300 to 900 g/m2, more preferably 350 to 600 g/m2. The basis weight of the liquid absorbent layer4at the other portions is preferably 200 to 700 g/m2.

As a result, the thickness is increased in the front central region20A and the rear central region20D so that the skin surface bulges toward the wearer's body in these regions, as shown inFIGS. 4 and 5.

The compressed grooves11–17are formed at a time by heat-embossing with the heating roller. As the topsheet3is pressed together with the liquid absorbent layer4at the front inner compressed grooves11A,11A and the front outer compressed grooves15,15, the density of the liquid absorbent layer4increases at the front side regions21,21due to tension given to portions of the topsheet3covering the front side regions21,21.

If the embossing projections arranged on the surface of the heating roller are adapted to have shallow grooves between projections for forming the front inner compressed grooves11A,11A and projections for forming the front outer compressed grooves15,15, furthermore, the liquid absorbent layer4can be pressed with the shallow grooves at the front side regions21,21as the front inner compressed grooves11A,11A and the front outer compressed grooves15,15are formed by pressing. In this case, therefore, the density of the liquid absorbent layer4can be increased more at the front side regions21,21. Likewise, the density of the liquid absorbent layer4can be increased more at the rear side regions24,24between the rear inner compressed grooves11D,11D and the rear outer compressed grooves16,16. The density can also be increased more at the rear region26than at the central region20.

The density of the liquid absorbent layer4at the front side regions21,21, the rear side regions24,24and the rear region26is preferably in the range of 0.08 to 0.2 g/cm3. On the other hand, the density of the liquid absorbent layer4at the central region20is preferably in the range of 0.05 to 0.18 g/cm3. The density of the liquid absorbent layer4at the other regions is preferably in the range of 0.05 to 0.13 g/cm3. It should be noted that the density of the liquid absorbent layer4at the front side regions21,21and the rear side regions24,24is preferably higher than that at the central region20by at least 0.01 g/cm3, more preferably, by at least 0.02 g/cm3.

It is preferred that the density of the high-density compressed portions10aand the density of the medium-density compressed portions10bfall within the range of 0.4 to 1.5 g/cm3.

The length of the central region20, i.e., the longitudinal distance between the front connecting compressed groove12and the rear connecting compressed groove14is about 130 to 350 mm. The width W1of the front central region20A on the lateral reference line Ox—Ox shown inFIG. 4is decided according to the width of the woman's genital organ. Because the crotch width of average women is about 30 mm, the width W1of the front central region20A is preferably in the range of 15 to 50 mm, more preferably in the range of 20 to 40 mm. On the other hand, the rear central region20D is so dimensioned as to easily fit in the cleft (Q) of the buttocks of the woman's body shown inFIG. 8, wherein the length, i.e., the longitudinal distance between the straight line20E connecting the inflected portions11B,11B and the rear connecting compressed groove14is about 60 to 150 mm. Here, the distance W2between the rear inner compressed grooves11D,11D at a position where the rear central region20D is longitudinally divided in two is in the range of 15 to 50 mm.

In regions adjacent the right and left side edges1aand1b, in which the liquid absorbent layer4does not exist, the backsheet2and the topsheet3are bonded together, and liquid-impermeable sheets30and30are laid on and bonded to the topsheet3and the backsheet2through a hot-melt adhesive, as shown inFIGS. 4 and 5. The wings1A and1A and the rear flaps1B and1B are mainly composed of the backsheet2and the liquid-impermeable sheets30.

The liquid-impermeable sheets30are folded in two with a plurality of elastically extensible members32interposed therebetween, wherein the confronting surfaces of the folded liquid-impermeable sheet30are bonded to each other. In front fixation regions33and33, the liquid-impermeable sheets30thus folded in two are refolded and then bonded and fixed to the skin surface in such a folded state. Also in rear fixation regions34and34, the liquid-impermeable sheets30are bonded and fixed to the skin surface in such a folded state. InFIG. 1, the front fixation regions33and33and the rear fixation regions34and34are indicated by hatching. The rear fixation region34is also shown in the sectional view ofFIG. 5.

Between the front fixation regions33,33and the rear fixation regions34,34, the liquid-impermeable sheets30and30are free within a given width, whereby the liquid-impermeable sheets30and30provide leakage preventing walls31and31. The elastically extensible members32exert a longitudinal elastic shrinkage force on the leakage preventing walls31and31. Front action ends35of the elastic shrinkage force are rear ends of the front fixation regions33, while rear action ends36of the elastic shrinkage force are front ends of the rear fixation regions34. The action ends35and the action ends36are attracted to each other due to the elastic shrinkage force, so that the sanitary napkin1is deformed with its skin surface recessed within an area of a distance L1between the action ends35and the action ends36. As a result, the leakage preventing walls31and31are raised from the skin surface within the area between the action ends35and the action ends36, as shown inFIG. 4.

As shown inFIG. 1, the front action ends35are in the same longitudinal position as the boundaries between the front inner compressed grooves11A and the front connecting compressed grooves12or in the vicinity thereof On the other hand, the rear action ends36are positioned in the vicinities of or slightly forward of the front ends16D of the rear outer compressed grooves16.

Accordingly, the elastic shrinkage force does not act on a front potion where the extension compressed grooves13and13are present, and therefore, the front portion can be freely deformed without being affected by the elastic shrinkage force. Similarly, since the elastic shrinkage force does not act on a rear portion where the rear outer compressed grooves16,16and the outer rear connecting compressed groove17are present, the rear portion of the sanitary napkin1can be easily deformed to provide a three-dimensionally concavely curved surface, as will be described hereinbelow.

On the exterior surface of the backsheet2, as shown inFIG. 3, pressure-sensitive adhesive layers41–44are provided. The pressure-sensitive adhesive layer41is disposed in a strip-shaped region elongated longitudinally to cover the backside compressed portion18. The pressure-sensitive adhesive layers42,42are disposed in the front portion of the sanitary napkin1symmetrically about the longitudinal centerline Oy—Oy so that one pressure-sensitive adhesive layer42is in a region elongated longitudinally to cover one front inner compressed groove11A and one front outer compressed groove15adjacent thereto and the other pressure-sensitive adhesive layer42is in a region elongated longitudinally to cover the other front inner compressed groove11A and the other front outer compressed groove15adjacent thereto. On the other hand, the pressure-sensitive adhesive layers43,43are disposed in the wings1A,1A; the pressure-sensitive adhesive layers44,44are disposed in the rear flaps1B,1B.

When the sanitary napkin1is to be attached to the wearer's body, the pressure-sensitive adhesive layer41and the pressure-sensitive adhesive layers42,42provided on the exterior surface of the backsheet2are adhered to an inner side of a groin piece51shown inFIG. 4, and at this time, the rear flaps1B,1B are also adhered to the inner side of the undergarment through the pressure-sensitive adhesive layers44,44. On the other hand, the wings1A,1A are folded back against an outer side of the undergarment to cover both side edges of the groin piece51, and adhered to the outer side of the groin piece51through the pressure-sensitive adhesive layers43,43provided on the garment surface of the wings1A,1A.

When the undergarment is worn with the sanitary napkin1attached to the groin piece51, as shown inFIG. 8, the area from the mons pubis (M) to the cleft (Q) of the buttocks in the woman's crotch can be covered with the skin surface of the sanitary napkin1.

When thus worn, the thighs exert a compressive force toward the longitudinal centerline Oy—Oy on the front outer compressed grooves15,15. The compressive force is transmitted to the front side regions21,21of a high density and a high stiffness via the front outer compressed grooves15,15, and further to the front inner compressed grooves11A,11A. Since the front outer compressed grooves15,15and the front inner compressed grooves11A,11A are located sufficiently below the midpoint of the thickness of the front central region20A, when the compressive force is exerted, the front outer compressed grooves15,15, the front side regions21,21and the front inner compressed grooves11A,11A try to get under the front central region20A, so that the front central region20A is supported from below and raised up toward the wearer's body into close contact with the vaginal opening (N) by the front side regions21,21of a high stiffness.

The front inner compressed grooves11A, the front side regions21and the front outer compressed grooves15arranged at both right and left sides of the article are fixed to the inner side of the groin piece51through the underlying pressure-sensitive adhesive layers42,42. Since the sanitary napkin1is adhered to the groin piece51with the separation distances between the front inner compressed grooves11A, between the front side regions21and between the front outer compressed grooves15maintained, when a compressive force is exerted on the groin piece51by the thighs, the sanitary napkin1can be deformed together to follow the deformation of the groin piece51, without causing displacement of the front inner compressed grooves11A, the front side regions21and the front outer compressed grooves15from the groin piece51. Therefore, the front central region20A to be deformed to bulge toward the wearer's body can always be positioned centrally of the groin piece51, so that the front central region20A can be easily brought into close contact with the vaginal opening (N).

In ordinary sanitary shorts, furthermore, elastically extensible members are provided centrally of a back body to extend along the cleft (Q) of the buttocks, so that when applied to the wearer's body, an elastic shrinkage force of the elastically extensible members acts on the groin piece51as a hanging-up force.

In the rear central region20D, the backside compressed portion18, in which the garment surface of the liquid absorbent layer4is recessed, is formed to extend in the longitudinal direction. When a pressure F1is applied to push up the backside compressed portion18toward the wearer's body due to the elastic shrinkage force, as shown inFIG. 7, the rear central region20D is deformed to bulge, easily coming into close contact with the anus (P) and fitting in the cleft (Q) of the buttocks.

As shown inFIG. 3, since the pressure-sensitive adhesive layer41is disposed beneath the backside compressed portion18, the portion having the backside compressed portion18can be firmly fixed to the undergarment. In addition, since the portion of the backsheet2where the pressure-sensitive adhesive layer41is disposed is bonded to the backside compressed portion18of the liquid absorbent layer4, the hanging-up force of the undergarment can certainly acts on the backside compressed portion18of the liquid absorbent layer4through the backsheet2, so that the portion intended to be deformed to bulge due to the presence of the backside compressed portion18can be prevented from being displaced from the center of the undergarment.

Since the backside compressed portion18is positioned within the rear central region20D and forward of the rear connecting compressed groove14, bulging deformation with the backside compressed portion18taken as a flexible hinge occurs only in the rear central region20D.

Since the rear central region20D is held between the rear inner compressed grooves11D,11D extending rearwardly to gradually decrease the separation distance therebetween and its rear end is closed by the rear connecting compressed groove14, when the rear central region20D is deformed to bulge toward the wearer's body, forces F2, F2act on the rear inner compressed grooves11D,11D to approximate them each other. When the portions outside the rear central region20D in such a state are pressed against the wearer's body by the undergarment, the portions laterally outside the rear central region20D and the portion behind the rear central region20D can be easily deformed along a curved surface indicated by curved lines X1and Y1ofFIG. 6, with the rear inner compressed grooves11D,11D and the rear connecting compressed groove14taken as flexible hinges.

That is, when the rear central region20D is deformed to bulge toward the cleft (Q) of the buttocks, the rear inner compressed grooves11D,11D and the rear connecting compressed groove14functioning as flexible hinges become the lowest parts in the concavely curved skin surface so that the right and left side edges1a,1band the rear end edge id of the sanitary napkin1project more toward the wearer's body than the flexible hinges. As a result, the portion extending outwardly from the flexible hinges to the right and left side edges1a,1band the rear end edge1dcan be deformed to provide a three-dimensionally concavely curved surface.

The present embodiment is constructed such that the rear outer compressed grooves16,16extending rearwardly to gradually decrease the separation distance therebetween and the outer rear connecting compressed groove17are further provided outside the rear inner compressed grooves11D,11D and the rear connecting compressed groove14, so that the rear central region20D is surrounded at its right, left and rear sides by doubled compressed grooves. Therefore, the rear inner compressed grooves11D,11D and the rear connecting compressed groove17function as inner flexible hinges, while the rear outer compressed grooves16,16and the outer rear connecting compressed groove17function as outer flexible hinges, whereby the rear portion of the sanitary napkin1can be deformed to provide a three-dimensionally concavely curved surface more easily.

In the rear side regions24,24and the rear region26, furthermore, the density of the liquid absorbent layer4is increased more than in the rear central region20D to increase the stiffness, and the rear central region20D is surrounded at its right, left and rear sides by these regions of a high stiffness. Therefore, the rear portion of the sanitary napkin1can be easily kept in the concavely curved state to thereby prevent the concavely curved rear portion from being twisted or wrinkled. Moreover, since the elastic shrinkage force of the elastically extensible members32used for raising the leakage preventing walls31,31does not act on the rear central region20D and its surroundings, the concavely curve surface of the rear portion of the sanitary napkin1will not be affected by the elastic shrinkage force of the elastically extensible members32.

With respect to the widened portion20B defined between the inflected portions11B,11B, furthermore, a compressive force from the front outer compressed grooves15,15and the front side regions21,21toward the longitudinal centerline Oy—Oy is applied to the front central region20A that is positioned forward of the inflected portions11B,11B, while a compressive force from the rear outer compressed grooves16,16and the rear side regions24,24toward the longitudinal centerline Oy—Oy is applied to the rear central region20D that is positioned rearward of the inflected portions11B,11B. Still furthermore, a compressive force is applied forward to the widened portion20B from the front ends16D,16D of the rear outer compressed grooves16,16due to a deforming force caused when the sanitary napkin1is concavely deformed according to the contour of the wearer's body and due to the elastic shrinkage force of the elastically extensible members32for raising the leakage preventing walls31.

As a result, the widened portion20B defined between the inflected portions11B,11B receives a compressive force from four directions, i.e., both in front and in the rear at both right and left sides thereof, so that the widened portion20B is deformed to bulge toward the wearer's skin as if it were picked up from four directions. Accordingly, the widened portion20B comes into close contact with the perineum (O) shown inFIG. 8.

In the sanitary napkin1in which the front central region20A can be deformed to bulge and come into close contact with the vaginal opening (N), as set forth above, the widened portion20B defined between the inflected portions11B,11B easily comes into close contact with the perineum (O), the rear central region20D easily enters the cleft (Q) of the buttocks, and the rear portion easily conforms to the curved surface of the buttocks. Therefore, most of menstrual blood discharged from the vaginal opening (N) can be passed through the liquid passage holes25and absorbed by the liquid absorbent layer4in the front central region20A, wherein menstrual blood trying to move rearward can be certainly collected by the rear central region20D in close contact with the area from the perineum (O) to the cleft (Q) of the buttocks. Moreover, since the rear portion of the sanitary napkin1deformed into the three-dimensionally concavely curved state shown inFIG. 6is able to come into close contact with the buttocks, outward leakage of menstrual blood from the rear portion can be effectively prevented during sleep and so on.

FIGS. 9 to 11are top plan views showing sanitary napkins according to other embodiments of the present invention.

In the embodiments shown inFIGS. 9 to 11, only the portions different from those of the first embodiment shown inFIG. 1and so forth will be described hereinbelow; the detailed description of the portions similar to those of the first embodiment ofFIG. 1will be omitted by designating them by the common reference numerals.

FIG. 9shows a sanitary napkin100, wherein short compressed grooves19,19are disposed between the rear inner compressed grooves11D,11D in the rear central region20D. The short compressed grooves19,19are formed in the same manner as the compressed grooves11–17. In the short compressed grooves19,19, therefore, the skin surface is recessed toward the garment surface with the liquid absorbent layer4compressed together with the topsheet3. The short compressed grooves19,19are relatively short and inwardly spaced an almost equal distance apart from the rear inner compressed grooves11D,11D.

When the portion of the rear central region20D having the backside compressed portion18is raised up toward the wearer's body by the hanging-up force of the undergarment, the short compressed grooves19,19, particularly, rear ends19a,19aof the short compressed grooves19,19function as starting points for folding, so that the region of the rear central region20D positioned between the rear ends19a,19aand the rear connecting compressed groove14can be easily deformed to bulge toward the wearer's body, as shown inFIG. 7.

FIG. 10shows a sanitary napkin100A. In the rear portion of the sanitary napkin100A, pressure-sensitive adhesive layers45,45are provided on the exterior surface of the backsheet2. The pressure-sensitive adhesive layers45,45are disposed symmetrically about the longitudinal centerline Oy—Oy. The pressure-sensitive adhesive layers45,45are similar in shape to but separate from the pressure-sensitive adhesive layer42,42provided in the front portion of the sanitary napkin100A.

The pressure-sensitive adhesive layers45,45are formed to cover the rear inner compressed grooves11D, the rear side regions24and the rear outer compressed grooves16. However, no pressure-sensitive adhesive layers are provided on the backsheet2at portions laterally outside the inflected portions11B,11B.

In the front portion of the sanitary napkin100A, since the front inner compressed grooves11A, the front side regions21and the front outer compressed grooves15are firmly fixed to the undergarment through the pressure-sensitive adhesive layers42,42, the front central region20A can be strongly compressed from both sides thereof by deformation of the undergarment during wear, thereby bulging toward the wearer's skin. In the rear portion, on the other hand, since the rear inner compressed grooves11D, the rear side regions24and the rear outer compressed grooves16are firmly fixed to the inner side of the undergarment through the pressure-sensitive adhesive layers45,45, the rear central region20D can be certainly compressed from both sides thereof by deformation of the undergarment during wear, so that the rear central region20D can be deformed to bulge toward the wearer's body.

Furthermore, since the pressure-sensitive adhesive layers42,42in the front portion and the pressure-sensitive adhesive layers45,45in the rear portion are independent from each other, the front central region20A and the rear central region20D can move independently from each other so as to follow the movement of the undergarment.

FIG. 11shows a sanitary napkin100B, wherein pressure-sensitive adhesive layers46,46are disposed symmetrically about the longitudinal centerline Oy—Oy. The individual pressure-sensitive adhesive layers46,46are in the shape of an elongated strip formed by integrating the adjacent pressure-sensitive adhesive layers42and45together in the longitudinal direction. Also in the sanitary napkin100B, right and left side portions of the front central region20A and right and left side portions of the rear central region20D are firmly fixed to the undergarment, so that the front central region20A and the rear central region20D can be certainly deformed by a lateral compressive force to bulge toward the wearer's body.

According to the present invention, as has been described hereinabove, the rear central region between the compressed grooves can easily come into close contact with an area from the anus to the cleft of the buttocks, and the rear portion can be deformed to provide a three-dimensionally concavely curved surface that can closely conform to the contour of the buttocks. Therefore, rearward leakage of menstrual blood from the absorbent article can be effectively prevented.

Although the present invention has been illustrated and described with respect to exemplary embodiments thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omission and additions may be made therein and thereto, without departing from the spirit and scope of the present invention. In the present invention, for instance, the presence of the rear inner compressed grooves11D,11D and the rear connecting compressed groove14enables easy deformation of regions outside them into a three-dimensionally concavely curved state. Therefore, the rear outer compressed grooves16,16and the outer rear connecting compressed groove17are not necessarily required. Accordingly, the present invention should not be understood as limited to the specific embodiments set out above but to include all possible embodiments which can be embodied within a scope encompassed and equivalent thereof with respect to the feature set out in the appended claims.