Absorbent article

The present invention aims to provide an absorbent article incorporated with a functional sheet without any anxiety that the wearer's skin might be contaminated even though the article is partially colored.In an absorbent article 1a comprising a sheet assembly 10, a functional sheet 51 having a size smaller than that of the sheet assembly 10, and a bodily fluid-absorbent structure 30 wherein the functional sheet 51 and the bodily fluid-absorbent structure 30 are attached to the sheet assembly 10, the functional sheet 51 is put flat with and bonded to the sheet assembly 10 so as to be kept in contact with the wearer's skin and an externally visible colored zone 4 is provided between the functional sheet 51 and the sheet assembly 10.

RELATED APPLICATIONS

The present application is a 35 U.S.C. §371 national stage filing of International Patent Application No. PCT/JP2007/074093, filed Dec. 14, 2007, to which priority is claimed under 35 U.S.C. §120 and through which priority is claimed under 35 U.S.C. §119 to Japanese Priority Patent Application No. 2007-24791, filed Feb. 2, 2007.

TECHNICAL FIELD

The present invention relates to an absorbent article including a functional sheet.

RELATED ART

It is well known to incorporate a functional sheet impregnated with antimicrobial agent or deodorant into the absorbent article such as disposable diaper or sanitary napkin and thereby to add the absorbent article with an additional function. The absorbent article according to this technique has sometimes been partially colored, for example, by printing in order to camouflage any intrinsic color of the antimicrobial agent or the other functional additives or in order to facilitate the article to be distinguished from the similar article without the functional sheet incorporated thereinto.

PATENT DOCUMENT 1 discloses the absorbent article provided in a region on the side thereof facing the wearer's skin extending outward beyond the peripheral edge of the absorbent core with a plurality of spots depressed in the thickness direction of this region wherein an appropriate quantity of ink is transferred into each of these depressed spots to form a printed pattern.PATENT DOCUMENT 1: Japanese Patent Application Laid-Open Publication No. 2006-181193 (claim 1, FIG. 1)

DISCLOSURE OF THE INVENTION

Problem to be Solved by the Invention

In the case of the absorbent article disclosed in PATENT DOCUMENT 1, the printed pattern serves to improve the leak-barrier effect and to give the wearer a feeling of assurance by making the wearer recognize such improvement of the leak-barrier effect.

However, it is apprehended that the printed pattern of ink provided directly on the side of the absorbent article facing the wearer's skin might fall away from the article and the wearer's skin might be contaminated therewith. Thus, there is a need for further improvement.

In view of the problem as has been described above which has been left behind unsolved by the prior art, it is a principal object of the present invention to provide an absorbent article incorporated with a functional sheet without any anxiety that the wearer's skin might be contaminated even though the article is partially colored.

Measure to Solve the Problem

The object set forth above is achieved, according to the present invention, by an improvement in the absorbent article comprising a sheet assembly, a functional sheet having a size smaller than that of the sheet assembly, and a bodily fluid-absorbent structure wherein the functional sheet and the bodily fluid-absorbent structure are attached to the sheet assembly.

The improvement according to the present invention is characterized in that the functional sheet is put flat with and bonded to the sheet assembly so as be kept in contact with the wearer's skin and an externally visible colored zone is provided between the functional sheet and the sheet assembly.

According to one preferred embodiment of the present invention, the functional sheet is bonded to the sheet assembly by the intermediary of an adhesive region, the adhesive region is provided so as to be spaced inward from an outer peripheral edge of the functional sheet, and the colored zone is provided in a same region as the adhesive region or within the adhesive region.

According to another preferred embodiment of the present invention, the colored zone is formed by at least one of ink with which the functional sheet is printed, ink with which the sheet assembly is printed, and hot melt adhesive used to bond the functional sheet to the sheet assembly and containing appropriate pigment.

According to still another preferred embodiment of the present invention, the bodily fluid-absorbent structure includes a liquid-absorbent material at least containing fluff pulp and the colored zone is provided in a region of the sheet assembly in which the liquid-absorbent material is not present.

Effect of the Invention

The absorbent article according to the present invention includes the external visible colored zone between the sheet assembly and the functional sheet. In consequence, the colored zone is covered with the functional sheet to prevent the wearer's skin from being contaminated with ink or the other coloring material.

The colored zone may be provided in the same region as the adhesive region or within the adhesive region to prevent, further reliably, the colored zone from coming in contact with the wearer's skin

The colored zone may be provided in the region of the sheet assembly in which the bodily fluid-absorbent material including fluff pulp is not present to improve the visibility of the colored zone since the colored zone is not masked by the bodily fluid-absorbent material including fluff pulp.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Details of the present invention will be described hereinafter on the basis of a disposable diaper1, one of typical examples of the invention, in reference to the accompanying drawings wherein the diaper1includes an antimicrobial sweat-absorbent sheet51as the functional sheet.

FIG. 1is a partially cutaway perspective view of the disposable diaper1according to the invention. The diaper1comprises a sheet assembly10including a top-sheet2, a back-sheet3and a leak-barrier sheet17as primary components, a sweat-absorbent sheet51of a size smaller than the sheet assembly10and a bodily fluid-absorbent structure30.

The top-sheet2adapted to be kept in contact with diaper wearer's skin is liquid-pervious and air-permeable while the back-sheet3serving as exterior material is liquid-impervious but air-permeable. These top- and back-sheets2,3are put flat together and partially bonded to each other by means of hot melt adhesive (not shown) to present a pants-like shape. The pants-type diaper1formed in this manner has a crotch region6adapted to face the wearer's crotch region, a front waist region7extending forward from the crotch region6and a rear waist region8extending rearward from the crotch region6. Specifically, the front and rear waist regions7,8respectively have transversely opposite lateral edges7a,7aand8a,8aalong which the front and rear waist regions7,8are put flat and fusion bonded together at bonding short bars9intermittently arranged in a vertical direction as viewed inFIG. 1. Thereupon, a waist-opening11and a pair of leg-openings12are formed.

The leak-barrier sheet17is liquid-impervious and sandwiched between the top-sheet2and the back-sheet3so as to extend across the crotch region6into the front waist region7and the rear waist region8. As indicated by a dashed line, the bodily fluid absorbent structure30is attached to an inner side (i.e., the side facing the wearer's skin) of the top-sheet2. In the vicinity of the waist-opening11, the sweat-absorbent sheet51having an externally visible colored zone4is bonded to the sheet assembly10of the diaper1in the rear waist region8in a manner that the sweat-absorbent sheet51may be kept in contact with the wearer's skin. Referring toFIG. 1, the colored zone4is provided on the rear surface of the sweat-absorbent sheet51and the range in which the colored zone4externally visible is indicated as a shaded region.

In the vicinity of a peripheral edge of the waist-opening11, a plurality of waist-surrounding elastic members13extending along the peripheral edge of the waist-opening11are sandwiched between the top-sheet2and the back-sheet3and bonded under tension to at least one of these top- and back-sheets2,3. In the vicinity of respective peripheral edges of the leg-openings12, a plurality of leg-surrounding elastic members14extending in parallel to the respective peripheral edges of the leg-openings12are sandwiched between the top-sheet2and the back-sheet3and bonded under tension to at least one of these top- and back-sheets2,3. In addition to these elastic members13,14, a plurality of auxiliary waist-surrounding elastic members16circumferentially extending in parallel to the waist-surrounding elastic members13are provided between front and rear edges7b,8bof the peripheral edge of the waist-opening11and the peripheral edges of the respective leg-openings12. These auxiliary waist-surrounding elastic members16are also sandwiched between the top-sheet2and the back-sheet3and bonded under tension to at least one of these top- and back-sheets2,3.

FIG. 2is a partially cutaway plan view showing the diaper1ofFIG. 1as the front and rear waist regions7,8have been torn apart from each other along the arrays of bonding short bars9and the diaper1as a whole has been developed in a transverse direction indicated by a double-headed arrow X as well as in a front-back direction orthogonal to the transverse direction X and indicated by a double-headed arrow Y. For a viewer ofFIG. 2, the top-sheet2, i.e., the side of the diaper1afacing the wearer's skin, is shown on the near side.

The sheet assembly10including the top-sheet2, the back-sheet3and the leak-barrier sheet17as the primary components has a contour in the crotch region6which curves inwardly of the diaper1aand thereby presents an hourglass-like shape as a whole. The top-sheet2constituting the sheet assembly10is provided in a central region with the bodily fluid-absorbent structure30covered with a liquid-absorbent top-sheet36. The bodily fluid-absorbent structure30extends across the crotch region6into the front waist region7as well as into the rear waist region8and has a shape symmetric about a longitudinal center line C-C substantially bisecting a transverse dimension of the diaper1a.

The bodily fluid-absorbent structure30is formed by liquid-absorbent material31such as fluff pulp or a mixture of fluff pulp and super-absorbent polymer particles sandwiched between a sheet of tissue paper32and a sheet of tissue paper and further covered with the previously described liquid-pervious top-sheet36directly facing the wearer's skin. The sheets of tissue paper32,33and the top-sheet36are substantially same in shape as well as in size and put flat together along transversely opposite lateral edges43,43extending in the front-back direction, front and rear ends41,42extending in the transverse direction of the bodily liquid-absorbent structure30. It should be appreciated that the top-sheet2is sandwiched between the bodily fluid-absorbent structure30and the leak-barrier sheet17in the case of the illustrated embodiment.

In the front and rear waist regions7,8of the diaper1a, the front edge7band the rear edge8bcooperating to define the peripheral edge of the waist-opening11inFIG. 1extend in the transverse direction inFIG. 2.

The back-sheet3is folded back along the front edge7band the rear edge8bonto the side of the diaper1aon which the bodily fluid-absorbent structure30is attached. The portion of the back-sheet3folded back along the front edge7bwill be referred to hereinafter as a front turnback46and the portion of the back-sheet3folded back along the rear edge8bwill be referred to hereinafter as a rear turnback47.

A front lower edge46adefined by a distal end of the front turnback46overlaps the front end41of the bodily fluid-absorbent structure30. A rear lower edge47adefined by a distal end of the rear turnback47also overlaps the rear end42of the bodily fluid-absorbent structure30but short of the liquid-absorbent material31.

Referring toFIG. 2, the front turnback46and the rear turnback47are bonded to the top-sheet2by means of adhesive52such as hot melt adhesive. The front turnback46and the rear turnback47are formed by the liquid-impervious back-sheet3and therefore it is not apprehended that a quantity of bodily fluids once having been absorbed by the bodily fluid-absorbent structure30might seep out from the bodily fluid-absorbent structure30in the front and rear waist regions7,8and come in contact with the wearer's skin.

The sweat-absorbent sheet51is substantially rectangular is bonded to the side of the rear turnback47facing the wearer's skin by the intermediary of an adhesive region61coated with hot melt adhesive57so that the sweat-absorbent sheet51may be kept in contact with the wearer's skin. The hot melt adhesive57is applied in dot-, stripe- or spiral-pattern. Between the sweat-absorbent sheet51and the rear turnback47, there is provided the externally visible colored zone4. It should be appreciated that the colored zone4is concealed behind the sweat-absorbent sheet51and therefore eliminated inFIG. 2.

A lower end50aand an upper end50bof the rectangular sweat-absorbent sheet51extend in the longitudinal direction thereof, i.e., in the transverse direction of the diaper1a, and substantially in parallel to the rear lower edge47aof the rear turnback47. A dimension of the sweat-absorbent sheet51as measured in the transverse direction of the diaper1ais larger than the corresponding dimension of the bodily fluid-absorbent structure30and same as or smaller than the corresponding dimension of the rear turnback47.FIG. 2shows the exemplary embodiment in which the sweat-absorbent sheet51fully extends between the transversely opposite lateral edges8a,8a. A dimension of the sweat-absorbent sheet51as measured between the lower end50aand the upper end50bthereof is smaller than a dimension of the rear turnback47as measured between the rear lower edge47aand a rear upper edge47bthereof.

The sweat-absorbent sheet51comprises a top layer and bottom layer each formed by air-permeable non-woven fabric of polyester fiber having a basis weight of 25 g/cm2and a middle layer formed by moisture-absorbent tissue paper impregnated with antimicrobial agent and having a basis weight of 2-0 g/cm2. After these three layers may be stacked on one another, this stack is subjected to impact of high-pressure to tangle component fibers of these layers and thereby to obtain the sweat-absorbent sheet51. When the sweat-absorbent sheet51of such construction comes in contact with the wearer's skin, sweat permeates, disperses from the top layer into the middle layer and can be held therein. In this way, uncomfortable wet feeling is eliminated and the wearer experiences pleasant cooling sensation.

The antimicrobial agent with which the middle layer of the sweat-absorbent sheet51functions to inhibit proliferation of microbes such asStaphylococcusepiermidis due to sweat and thereby to inhibit development of heat rash due to such microbes. Such antimicrobial agent may be selected from a group of quaternary ammonium salts such as alkylpyridinium salt, alkylammonium salt, alkylbenzildimethyl ammonium salt (benzalkonium chloride), dialkyldimethyl ammonium salt and benzethonium chloride. Such antimicrobial agent may include additive, for example, catechin, if desired.

The adhesive region61in which the sweat-absorbent sheet51is bonded to the rear turnback47is provided so as to be spaced inward from an outer peripheral edge58of the sweat-absorbent sheet51and implemented as small dots of hot melt adhesive57distributed at a rate of 1 to 20 dots/cm2. Between the outer peripheral edge58and the adhesive region61of the sweat-absorbent sheet51, a non-adhesive region62is left, in which the sweat-absorbent sheet51is free from the rear turnback47. As will be apparent fromFIG. 2, the outer peripheral edge58of the sweat-absorbent sheet51includes the lower end50aand the upper end50b.

The colored zone4is defined by or within the adhesive region61so as to extend outside the rear end42of the bodily fluid-absorbent structure30. In other words, the colored zone is spaced from the outer peripheral edge58of the sweat-absorbent sheet51and is provided in a zone of the sheet assembly10constituting the diaper1ain which the liquid-absorbent material31containing fluff pulp is not present.

FIG. 3is a sectional view taken along a line inFIG. 2. The sweat-absorbent sheet51is bonded to the turnback47of the back-sheet3by the intermediary of the adhesive region61so as to be kept in contact with the wearer's skin and includes the non-adhesive region62between the adhesive region61and the outer peripheral edge58of the sweat-absorbent sheet61.

The colored zone4is defined by a plurality of ink dots59printed on the sweat-absorbent sheet51in the same regions as the adhesive region61so as to be sandwiched between the sweat-absorbent sheet51and the turnback47. These ink dots4are arranged within a zone spaced from the rear end42of the bodily fluid-absorbent structure30.

As will be apparent fromFIG. 3, the colored zone4is visible from the side of the diaper1afacing the wearer's skin through the sweat-absorbent sheet51formed by non-woven fabric. In other words, the wearer or the helper can make sure that the diaper1ais of the type provided with the sweat-absorbent sheet51and determine the position of this sweat-absorbent sheet51merely by opening the diaper1ain the pants-shape adapted to be put on the wearer's body. Thus it is easily possible to position the sweat-absorbent sheet51properly on the rear waist region of the wearer.

The sweat-absorbent sheet51is provided in the region of the diaper1afree from the presence of the liquid-absorbent material31including the fluff pulp. With such arrangement, the colored zone4is easily visible through the top-sheet2and the turnback47of the back-sheet3and there is no anxiety that the colored zone4might be shielded by the liquid-absorbent material31which is impenetrable to light. The wearer or the helper is allowed thereby to eliminate the need for opening the diaper1ain the pants-shape in order to make sure that the diaper1ais of the type provided with the sweat-absorbent sheet51.

The colored zone4is provided so as to be sandwiched between the sweat-absorbent sheet51and the turnback47of the back-sheet3and thereby covered with the sweat-absorbent sheet51. With this arrangement, there is no possibility that the colored zone4might come in direct contact with the wearer's skin and the wearer's skin might be contaminated with a quantity of ink51rubbed off from the colored zone4.

In addition, the colored zone4is provided within the adhesive region61, leaving the non-adhesive region62. Even if the force tending to curl up the sweat-absorbent sheet51is exerted thereupon in the course of putting the diaper1aon the wearer's body or due to movement of the wearer, the non-adhesive region62is sufficiently deformable to be curled up in first as indicated by an arrow Z inFIG. 3and thereby to restrict a possibility that the sweat-absorbent sheet51might be curled up over the unacceptable range. Consequentially, there is no anxiety that the colored zone4might be exposed due to curling up of the sweat-absorbent sheet51over the unacceptable range and the wearer's skin might be contaminated with ink rubbed off from the colored zone4. A width dimension of such non-adhesive region62, i.e., a distance between the outer peripheral edge58of the sweat-absorbent sheet51and the adhesive region61is at least 1 mm or larger, preferably 3 mm or larger.

Ink59used to form the colored zone4is not specified and may be appropriately selected from a group commonly used in the relevant technical field depending on the materials of the sweat-absorbent sheet51and the sheet assembly10. To improve the visibility of the colored zone4, it is preferred to enhance a differential light value between the colored zone4and the sweat-absorbent sheet51and the turnback47of the back-sheet3both covering the colored zone4. In general, the absorbent article is typically made using white non-woven fabric. If the white non-woven fabric used as stock material for the absorbent article is of poor see-through, printing ink of lower light value, for example, black, blue or green printing ink may be used to enhance the differential light value with respect to this non-woven fabric and thereby to improve the visibility of the colored zone4.

According to one exemplary embodiment of the colored zone4provided within the adhesive region61, the dots of hot melt adhesive57and the dots of ink59may be arranged in alternate shifts to present a printing pattern of ink59as schematically illustrated byFIG. 4(a). By printing the sweat-absorbent sheet with the dots of ink59in this manner, it is possible to restrict an increase in stiffness of the sweat-absorbent sheet51compared to the case in which the sweat-absorbent sheet51is printed with continuous lines of ink59and thereby to maintain comfortable drape of the non-woven fabric constituting the sweat-absorbent sheet51.

To keep a desired air-permeability of the sweat-absorbent sheet51, a total coated area of ink59is preferably limited to 30% or less with respect to a total area of the adhesive region61. To reduce the total coated area of ink59as effectively as possible, a central zone of the adhesive region61as viewed inFIG. 4(a) may be left not printed with ink59. Alternatively, it is also possible to replace the filled dots of ink59by small rings each defined by an outer diameter of 1.0 mm and an inner diameter of 0.6 mm or less encircling a non-printed area.

Even if the sweat-absorbent sheet51is printed with ink59in a pattern of the small rings each having the inner diameter of 0.6 mm or less encircling the non-printed area as has been described above, it is difficult for the naked eye to distinguish the small rings from the filled dots of ink59. This is for the reason that the outline of the small ring necessarily blurs through the non-woven fabric and the non-printed area can not be visually recognized. Taking account of this, the sweat-absorbent sheet51may be advantageously printed with ink59in the pattern of small rings distributed in the given region to reduce the total printed area while the same level of visibility as the case of printing in the pattern of filled dots. In this way, it is possible to obtain the sweat-absorbent sheet51exhibiting high air-permeability.

Alternatively, the sweat-absorbent sheet51may be printed with ink59inside the adhesive region61as illustrated byFIG. 4(b) to provide the colored zone4inside the adhesive region61. With this arrangement, the portion of the sweat-absorbent sheet51extending outward beyond the colored zone4is sealed by the adhesive region61and thereby effectively protects the wearer's skin from being contaminated with ink59even if the sweat-absorbent sheet51is partially curled up. It should be appreciated that the portions of the sweat-absorbent sheet51and/or the back-sheet3or the other sheets constituting the sheet assembly10which respectively correspond to the adhesive region61have been previously printed with ink59.

It is also possible to use hot melt adhesive containing an appropriate pigment to form the colored zone4. With such arrangement, the wearer's skin can be effectively protected from contamination and the step of printing with ink59can be eliminated since the pigment is reliably sealed in the hot melt adhesive.

Patterns in which the sweat-absorbent sheet51serving as the functional sheet may be printed with ink59are schematically illustrated byFIG. 5(a)-FIG. 5(c). While the invention will be described hereinafter with respect to the case in which the sweat-absorbent sheet51is printed with ink59, it is also possible to print the sheet assembly10with ink59. The colored zone4may be formed by printing the rectangular sweat-absorbent sheet51with ink59in the pattern of dots so that the colored zone4is spaced from the lower end50aand the upper end50band comes in contact with the transversely opposite lateral edges50c,50dof the rectangular sweat-absorbent sheet51as illustrated byFIG. 5(a). Alternatively, the colored zone4may be formed by printing the rectangular sweat-absorbent sheet51with ink59in the pattern of dots so that the colored zone4comes in contact with the lower end50aand the upper end50band is spaced from the transversely opposite lateral edges50c,50dof the rectangular sweat-absorbent sheet51as illustrated byFIG. 5(b).

The sweat-absorbent sheet51is coated with hot melt adhesive57in pattern of stripes extending in the longitudinal direction of the sheet51to form the adhesive region61fully extending between the transversely opposite lateral edges50c,50dso as to leave the non-adhesive regions62extending along the lower end50aand the upper end50bas illustrated byFIG. 5(a). Alternatively, the sweat-absorbent sheet51may be coated with hot melt adhesive57in pattern of stripes extending in the vertical direction orthogonal to the longitudinal direction so as to leave the non-adhesive regions62extending along the lateral sides50c,50das illustrated byFIG. 5(b). As seen in both cases, the non-adhesive regions62may be left not along the complete outer periphery but along a part of the outer periphery of the sweat-absorbent sheet51.

It should be noted here that the sweat-absorbent sheet51attached to the diaper1aso that the longitudinal direction thereof may be parallel to the transverse direction of the diaper1a, the sweat-absorbent sheet51is apt to be curled up in the vertical direction due to movement of the wearer's body. To overcome such problem, the sweat-absorbent sheet51may be coated with hot melt adhesive57extending in the vertical direction as illustrated byFIG. 5(b) to leave the non-adhesive regions61extending in vertical direction from the lower end50ato the upper end50b. In this way, undesirable curling up of the sweat-absorbent sheet51can be reliably restricted even if the wearer's body moves.

According to another exemplary embodiment, the sweat-absorbent sheet51may be printed with ink59in the pattern of dots distributed in the region spaced from the lower end50a, the upper end50band the transversely opposite lateral edges50c,50dof the sweat-absorbent sheet51. In this case, the sweat-absorbent sheet51may be coated with hot melt adhesive57in stripe-pattern extending in the longitudinal direction or in the vertical direction of the sweat-absorbent sheet51as illustrated. In each case, it is essential to print the sweat-absorbent sheet51with ink59in the same region as the adhesive region61to be coated with hot melt adhesive57or within this adhesive region61.

As has previously been described, the sweat-absorbent sheet51is implemented in the form of the laminate comprising the top and bottom layers formed by non-woven fabric of polyester fiber and the middle layer formed by tissue paper entangled together under impact of high pressure water stream.

The surface of the sweat-absorbent sheet51directly subjected to impact of high pressure water stream (referred to hereinafter as the impacted surface) and the surface opposite to the impacted surface (referred to hereinafter as the opposite surface) of the sweat-absorbent sheet51were compared to each other using Scanning Electron Microscope (SEM) of JSM-5800 Model manufactured by JEOL Ltd. It was found from this microscopic comparison that many of the component fibers on the impacted surface are oriented in one direction with relatively few intersections (SeeFIG. 6). In contrast with this, the component fibers on the opposite surface were oriented under a bouncing effect of high pressure water stream at the moment of impacting of high pressure water stream rather at random than on the impacted surface and the number of intersections was correspondingly increased (SeeFIG. 7).

Fewer intersections of the component fibers on the impacted surface make the impacted surface smoother than the opposite surface.

In other words, the opposite surface of the sweat-absorbent sheet51may be printed with ink59and thereby the colored zone4may be formed to ensure that the colored zone4is easily visible when the colored zone4is observed through the smooth impacted surface from the side of the sweat-absorbent sheet51facing the wearer's skin. In addition, the smooth impacted surface lying on the side facing the wearer's skin serves to improve close contact of the sweat-absorbent sheet51with the wearer's skin and thereby to improve efficiency of sweat-absorbent and antimicrobial function for the wearer's skin.

From SEM observation of the sweat-absorbent sheet51printed with ink59, it was found that a quantity of ink59clings, at each of the intersections of the component fibers, in form of film extending between each pair of the adjacent component fibers (SeeFIG. 8) over an area larger than an area over which the same quantity of ink59clings to the single component fiber (SeeFIG. 9). In other words, the same quantity of ink59is able to color the sweat-absorbent sheet51over the area larger at each of the intersections than on the single fiber. In consideration of this, the opposite surface including many intersections of the component fibers may be printed with the same quantity of ink59to form the colored zone4presenting relatively high visibility.

As will be obvious from the description given heretofore, the sweat-absorbent sheet51is preferably formed by subjecting the laminate comprising the liquid-absorbent middle layer and the top and bottom layers both being air-permeable and liquid-pervious and formed by the air-permeable and liquid-pervious fibrous non-woven fabric made of synthetic resin to the impact of high pressure water stream directed from the top layer toward the bottom layer so as to intertangle the component fibers of the laminate. The bottom layer side (the opposite surface) of the sweat-absorbent sheet51formed in this manner may be provided with the colored zone4and the top layer (the impacted surface) may be bonded to the sheet assembly10so as to be kept in contact with the wearer's skin to improve visibility of the colored zone4and close contact of the sweat-absorbent sheet51with the wearer's skin.

While the exemplary embodiments have been described above, the present invention is not limited to these embodiments and details thereof may be modified in various manners without departing from the scope of the invention.

For example, while the sweat-absorbent sheet51has been described to comprise tissue paper sandwiched a pair of non-woven fabric layers made of polyester fiber, the invention is not limited to such embodiment so far as the sweat-absorbent sheet51is of trilaminar structure consisting of the liquid-absorbent middle layer reinforced by the top and bottom layers both made of air-permeable and liquid-pervious non-woven fabric of synthetic resin fiber or film. It is possible therefore to use hydrophilic fiber containing cellulose, for example, rayon, cotton or pulp as stock material for the middle layer. As stock material of the top layer and the bottom layer, it is possible to use air-permeable and liquid-pervious fibrous non-woven fabric or film, for example, of polyethylene or polypropylene.

When non-woven fabric is used for the top layer and the bottom layer, two or more types of fibers may be mixed together. For example, polyester fiber modified to become hydrophilic may be mixed to improve the liquid-pervious property of the sweat-absorbent sheet51. To modify polyester fiber to become hydrophilic, for example, polyethylene glycol may be blended with polyester or graft polymerized with polyester to achieve desired modification.

While the sheet assembly10has been described to comprise the top-sheet2, the back-sheet3and the leak-barrier sheet17as basic components, it is possible to increase the number of component sheets constituting the sheet assembly10, for example, by bisecting the top-sheet2. Alternatively, the top-sheet2and the back-sheet3may be put flat together and bonded to each other along the front edge7band the rear edge8bwithout folding back the back-sheet3. Ink59forming the colored zone4may contain ingredients other than pigment, for example, appropriate agent having solvatochromic property to water such as cobalt chloride(II).

While the exemplary embodiment has been described above in which the colored zone4is formed so as to be spaced from the rear end42of the bodily fluid-absorbent structure30, the position relationship between the colored zone4and the bodily fluid-absorbent structure30is not limited to such exemplary embodiment. For example, the colored zone4may partially overlap the tissue paper layers32,33constituting the bodily fluid-absorbent structure30or partially overlap the liquid-absorbent material31.

In other words, the colored zone4may be formed at the position corresponding to the position of the functional sheet (i.e., sweat-absorbent sheet51) and sandwiched between the functional sheet and the sheet assembly10so as to be externally visible. Position and size of the functional sheet relative to the bodily fluid-absorbent structure30as well as to the liquid-absorbent material31may be appropriately selected.