Sanitary napkins

Abstract: A sanitary napkin (10) includes liquid barriers (15) and wings (16), wherein the liquid barriers (15) can be freely erected without any hindrance due to folding back of the wings (16). The sanitary napkin (10) comprises the above-mentioned liquid barriers (15) extending along laterally opposite sides thereof and provided with elastic members, respectively, and the above-mentioned wings (16) outwardly extending from the respective liquid barriers (15). The liquid barriers (15) and the wings (16) are branched from each other so that the liquid barriers (15) are not pulled outward even when the respective wings (16) are folded back onto the outer surface of a crotch zone of the user's shorts in order to fix the napkin thereto.

Description: This invention relates to sanitary napkins (or sanitary pads or towels)used to absorb and hold menstrual discharges and more particularly to such sanitary napkins provided with wings and liquid barriers adapted to be folded back around a crotch zone of the user's shorts or underpants in order to fix the napkin thereto. Conventional sanitary napkins classified herein for the purpose of explanation as napkins of a first type comprise a liquid-permeable topsheet, a liquid-impermeable backsheet, a liquid-absorbent core sandwiched therebetween, and wings formed by sections of the top- and backsheets which outwardly extend from laterally opposite side edges of the liquid-absorbent core at a longitudinally middle portion of the liquid-absorbent core. In actual use of napkins of this type, the wings are folded back onto the outer surface of a crotch zone of the user's shorts and thereby the wings are fixed thereto with adhesive applied to rear sides of the respective wings. Thus, the napkins are advantageous in that it can be reliably fixed to the crotch zone. Such a sanitary napkin is described in patent GB-A-2214085. Well known sanitary napkins classified as napkins of a second type include liquid barriers longitudinally extending along laterally opposite sides and adapted to be erected under the effect of elastic elements associated with the respective liquid barriers. Napkins of this type are advantageous in that the liquid barriers effectively contribute to prevent body fluids from leaking laterally. Prior art sanitary napkins classified as napkins of a third type comprise an upper napkin and a lower napkin dimensioned wider than the upper napkin so that the former is fixed to the latter at longitudinally opposite ends of the latter In use of napkins of this type, the lower napkin is fixed to a crotch zone of the user's shorts with adhesive applied on a rear side of the lower napkin. Thus, such composite napkins are advantageous in that the upper napkin is free from any adverse influence of deformation possibly occurring in the crotch zone of the user's shorts. However, the napkins of the first and third types are inferior to the napkins of the second type with respect to the preventive effect against lateral leakage of body fluids because both the napkins of the first type and the napkins of the third type have no liquid barriers characterizing the napkins of the second type. The napkins of the second type are, in turn, inferior to the napkins of the first type as far as fixation of the napkin to a crotch zone of the user's shorts is concerned. In view of this, the inventors attempted to obtain sanitary napkins having combined advantageous features of these first and second types and found that the advantageous feature of the second type can not satisfactorily function when these two advantageous features are merely combined with one another. More specifically, with such composite napkins well known in the art, the liquid barriers provided on the component napkin of the second type are pulled outward against the contractile force of the associated elastic members as the wings provided on the component napkin of the first type are fixed to the user's shorts by folding the wings back onto an outer side of the crotch zone thereof, with a disadvantageous consequence that the liquid barriers can not satisfactorily operate. In view of these problems remaining unsolved in spite of various efforts which have been attempted by prior art napkins, it is a principal object of the invention to provide improved sanitary napkins which maintain the advantages expected from all of the above-mentioned first, second and third types in combination. The object set forth above is achieved, according to one aspect of the invention, by a sanitary napkin composed of a liquid-permeable topsheet, a liquid-impermeable backsheet, a liquid-absorbent core sandwiched therebetween, and two spaced apart wings outwardly extending from laterally opposite sides of the liquid-absorbent core substantially at a longitudinal middle portion of the liquid-absorbent core and applied with adhesive at least on rear sides of the wings, each wing having an inner root portion and an outer portion, the outer portion being adapted to be folded around a side edge of a crotch of a wearer's undergarment, and two spaced apart liquid barriers each located inwardly of one of the wings and extending longitudinally adjacent the inner root portion of the associated wing characterised in that each liquid barrier comprises a portion of the topsheet which is folded over so as to extend upwardly with respect to and away from the backsheet and then inwardly to the liquid-absorbent core so as to form a free barrier upper end which is branched with respect to the inner root portion of the associated wing so that each free barrier upper end will not be affected by an outwardly pulling force when its associated wing is folded around a side edge of a crotch of the undergarment. The object set forth above is also achieved, according to a second aspect, by a sanitary napkin composed of an upper napkin including a liquid-absorbent core covered with at least a liquid-permeable topsheet and a relatively wide lower napkin including a liquid-impermeable backsheet on a top surface of which a liquid-permeable sheet is bonded at least along opposite side edges of the backsheet so that the upper napkin is bonded to the lower napkin at longitudinally opposite ends of the lower napkin, the sanitary napkin being characterised in that the upper napkin includes two spaced apart liquid barriers extending longitudinally along laterally opposite sides thereof which extend upwardly with respect to and away from a lower side of the liquid-absorbent core, each liquid barrier having a free upper end that encloses an elastic member which assists in positioning each liquid barrier in an erected position, the lower napkin including two spaced apart wings which extend outwardly beyond laterally opposite sides of the liquid-absorbent core substantially at a longitudinal middle portion of the lower napkin, each wing having an inner portion and an outer portion, the outer portion being adapted to be folded around a side edge of a crotch of the wearer's undergarment, and each wing having adhesive applied thereto at least on a rear side thereof. For implementation of both the first and second aspects, it is preferred to form the wings at least from top- and backsheets bonded together and to provide the inner side edges of said topsheets with respective elastic members assisting the inner side edges to be erected. For implementation of the second aspect, on the other hand, it is preferred to sandwich a liquid-absorbent core between the top- and backsheets of the lower napkin. The invention will be described in more detail with reference to the attached drawings, in which: FIG. 1 is a perspective top view showing an embodiment of a sanitary napkin constructed according to the teachings of the invention; FIG. 2 is a perspective bottom view showing the sanitary napkin: FIG. 3 is a sectional view, in an enlarged scale, taken along a line 3-3 in Fig. 1; Fig. 4 is a view similar to Fig. 3 showing another embodiment of the sanitary napkin constructed according to the teachings of the invention; and Fig. 5 is a sectional view showing, in an enlarged scale, the sanitary napkin shown by Fig. 3 as has been fixed to a crotch zone of the user's shorts. Referring to Figs. 1 to 3, a napkin 10 basically comprises a liquid-permeable topsheet 11, a liquid-impermeable first backsheet 12, a liquid-impermeable second backsheet 13 underlying and bonded to the first backsheet 12, and a liquid-absorbent core 14 which is smaller than the above-mentioned sheets both in length and width and sandwiched between the topsheet 11 and the first backsheet 12 so that these sheets partially extend beyond the absorbent core 14 in the form of extensions 11a, 12a, 13a. The absorbent core 14 is provided along laterally opposite sides with liquid barriers 15 and wings 16 which outwardly extend from the respective liquid barriers 15. It is also possible without departure from the scope of the invention to employ a first backsheet 12 which is liquid-permeable Each liquid barrier 15 is formed by successive steps of folding the outer extension 11a substantially along a longitudinally middle length thereof up- and inward, bonding an inner edge of this fold to the top of the absorbent core 14 so as to form a sleeve, placing an elastic member 17, as it is stretched, longitudinally inside an outer edge of said sleeve and fixing the elastic member 17 to said sleeve at least at longitudinally opposite ends thereof. Each wing 16 comprises second outer extensions 12b, 13b extending further outward beyond the outer extensions 12a, 13a at a location adjacent the front end of the napkin 10 and a liquid barrier sheet 18 which comprises, in turn, an inner section 18a bonded to the top of the outer extension 12a, an outer extension 18b being identical to the second outer extensions 12b, 13b in size as well as in configuration and bonded to the top of second outer extension 12b, and downwardly folded back section 18c being continuous with the inner section 18a. An elastic member 19 is placed, as it is stretched, inside an inner edge of a sleeve formed by the folding back longitudinally of the sleeve and fixed to the sleeve at least at longitudinally opposite ends of the elastic member 19. If it is desired to provide the liquid barrier 15 with liquid-impermeability, the liquid barrier 15 may be subjected to a suitable water repelling treatment, or a width of the first backsheet 12 may be dimensioned to be substantially equal to a width of the topsheet 11 and outer edges of these sheets may be formed into the liquid barrier 15 as shown, or a separately provided liquid-impermeable sheet may be sandwiched between the absorbent core 14 and the first backsheet 12. Referring to Fig. 4, another embodiment is shown. A napkin 110 comprises an upper napkin 110a and a lower napkin 110b which is wider than the upper napkin 110a. The upper napkin 110a is fixed at longitudinally opposite ends thereof to the top of the lower napkin 110b. The upper napkin 110a comprises a liquid-permeable topsheet 111, a liquid-impermeable backsheet 112, a liquid-absorbent core 114 which is smaller than the above-mentioned sheets both in length and width and sandwiched therebetween so that these sheets partially extend beyond the absorbent core 114 as respective outer extensions 111a, 112a. The absorbent core 114 is provided along laterally opposite sides with liquid barriers 115. Each liquid barrier 115 is formed by successive steps of folding the outer extensions 111a, 112a up- and inward, bonding inner edges of these folded portions to the non-folded portions to form a sleeve, placing an elastic member 117, as it is stretched, longitudinally inside an outer edge of the sleeve and fixing the elastic member 117 to the sleeve at least at longitudinally opposite ends thereof. It is also possible without departure from the scope of the invention to employ a backsheet 112 which is liquid-permeable. The lower napkin 110b comprises a liquid-permeable topsheet 211, a liquid-impermeable backsheet 212. a liquid-absorbent core 214 which is smaller than the above-mentioned sheets both in length and width and sandwiched between said two sheets, and wings 116 extending outward from laterally opposite sides of the liquid-absorbent core 214, respectively. More specifically, each wing 116 comprises second outer extensions 211b, 212b outwardly extending further beyond respective outer extensions 211a, 212a of the top- and backsheets 211, 212 which, in turn, outwardly extend from each lateral side of the liquid-absorbent core 214 and a liquid-barrier sheet 118. The wing 116 is similar to the previously mentioned wing 16 in configuration as will be apparent from comparison with Fig. 3, except that an inner section 118a of the liquid barrier sheet 118, which is folded back to define an inner end of the wing 116 and contains therein an elastic member 119,is overlaid on a side edge of the liquid-absorbent core 214 with the topsheet 211 interposed therebetween. An alternative arrangement (not shown) is also possible within the scope of the invention wherein the lower napkin 110b has no liquid-absorbent core 214. Referring to Figs. 3 and 4 (see Fig. 2 also), outer surfaces of the sheets 13, 212 are applied at their central zones with adhesive 20, 120 each in a narrow strip extending in parallel to the longitudinal direction of these sheets 13, 212 while bottom surfaces of the wings 16, 116 are applied at their central zones with adhesive 21, 121 each in a square shape, and these adhesive zones are protected by covering them with release sheets 22, 122 and 23, 123, respectively. Now, a manner in which the napkin 10 constructed as has been mentioned hereinabove is actually used will be described. (No description will be made here in connection with the napkin 110.) The release sheet 22 is removed to expose the adhesive 20 with which the napkin 10 is fixed at its central zone to an inner side of the user's shorts at a central zone 25 thereof (see Fig. 5), then the release sheets 23 are removed to expose the adhesive 21 and the wings 16 are folded back onto an outer side of the crotch zone of the user's shorts so as to fix the wings 16 thereto with the adhesive 21. With the napkin being fixed to the user's shorts in this manner, a free upper end of the liquid barrier 15 and an inner edge of the inner section 18a defining an inner end of the wing 16 are erected under contractile force of the respective elastic members 17, 19. During such erection, the liquid barrier 15 is free from any pulling force directed outward due to folding back of the wing 16. It should be understood here that provision of the elastic member 19 is not essential because the inner edge of the inner section 18a can be erected as the wing 16 is folded back even if the elastic member 19 is not provided, i.e., the elastic member 19 serves merely to assist the inner edge to be erected. Respective components of the napkin 10, 110 may be made of the materials used for corresponding components of conventional napkins. For example, the topsheets 11, 111, 211 may be made of nonwoven fabric or porous plastic film, the backsheets 12, 112, 212 may be made of plastic film and the liquid barrier sheets 18, 118 may be made of water repellent nonwoven fabric. With the sanitary napkin of this invention having the construction and the operation as have been described hereinabove, the liquid barrier is never pulled outward by the wings against the contractile force of the elastic member provided within the liquid barrier but is erected under the contractile force of this elastic member closely against skin of the user's private parts and thereby satisfactorily prevents body fluid from partially leaking in the lateral directions. With the embodiment of the sanitary napkin so arranged that the inner edge of the sheet used to constitute the top of each wing normally rises up, this inner edge also contributes to prevent any quantity of body fluids from leaking laterally. With the embodiment of the sanitary napkin comprising the upper napkin and the lower napkin, the upper napkin can be properly kept in close contact with skin of the user's private parts without adverse influence of deformation such as wrinkles and twists possibly appearing in the lower napkin and/or the crotch zone of the user's shorts, so that lateral leakage can be more effectively avoided.

Claims: A sanitary napkin comprising a liquid-permeable topsheet (11), a liquid-impermeable backsheet (12, 13), a liquid-absorbent core (14) sandwiched therebetween, and two spaced apart wings (16) outwardly extending from laterally opposite sides of the liquid-absorbent core (14) substantially at a longitudinal middle portion of the liquid-absorbent core (14) and applied with adhesive (21) at least on rear sides of the wings (16), each wing (16) having an inner root portion and an outer portion, the outer portion being adapted to be folded around a side edge of a crotch of a wearer's undergarment, and: two spaced apart liquid barriers (15) each located inwardly of one of the wings (16) and extending longitudinally adjacent the inner root portion of the associated wing (16), characterized in that each liquid barrier (15) comprises a portion of the topsheet (11) which is folded over so as to extend upwardly with respect to and away from the backsheet (12, 13) and then inwardly to the liquid-absorbent core (12) so as to form a free barrier upper end which is branched with respect to the inner root portion of the associated wing (16) so that each free barrier upper end will not be affected by an outwardly pulling force when its associated wing (16) is folded around a side edge of a crotch of the undergarment The sanitary napkin claimed in claim 1, wherein each wing (16) comprises a barrier sheet (18) overlying and bonded to the backsheet (12, 13), the side of each barrier sheet (18) which is closest to the core (14) being folded over to form a sleeve which is raised up with respect to the remainder of the associated wing (16). The sanitary napkin claimed in claim 2, wherein each sleeve encloses a stretched elastic member (19) which assists in positioning the sleeve in a raised position. The sanitary napkin claimed in any preceding claim, wherein each liquid barrier (15) encloses a stretched elastic member (17) which assists in positioning the liquid barrier (15) in its upwardly extending position. A sanitary napkin comprises an upper napkin (110a) including a liquid-absorbent core (114) covered with at least a liquid-permeable topsheet (111) and a relatively wide lower napkin (110b) including a liquid-impermeable backsheet (212) on a top surface of which a liquid-permeable sheet (211) is bonded at least along opposite side edges of the backsheet (212) so that the upper napkin (110a) is bonded to the lower napkin (110b) at longitudinally opposite ends of the lower napkin, the sanitary napkin being characterised in that: the upper napkin (110a) includes two spaced apart liquid barriers (115) extending longitudinally along laterally opposite sides thereof which extend upwardly with respect to and away from a lower side of the liquid-absorbent core (114), each liquid barrier (115) having a free upper end that encloses an elastic member (117) which assists in positioning each liquid barrier (115) in an erected position, the lower napkin (110b) including two spaced apart wings (116) which extend outwardly beyond laterally opposite sides of the liquid-absorbent core (114) substantially at a longitudinal middle portion of the lower napkin (110b), each wing (116) having an inner portion and an outer portion, the outer portion being adapted to be folded around a side edge of a crotch of the wearer's undergarment, and each wing (116) having adhesive (121) applied thereto at least on a rear side thereof. The sanitary napkin claimed in claim 5, wherein each wing (116) comprises the backsheet (212) and an overlying barrier sheet (118), the side of each barrier sheet (118) which is closest to the liquid barrier (115) being folded over to a form a sleeve which is raised up with respect to the remainder of the associated wing (116). The sanitary napkin claimed in claim 6, wherein each sleeve encloses a stretched elastic member (119) which assists in positioning the sleeve in a raised position. The sanitary napkin claimed in claim 5, 6 or 7, wherein each liquid barrier (115) comprises a portion of the topsheet (111) which is folded over so as to extend upwardly with respect to the backsheet (212) The sanitary napkin claimed in any one of claims 5 to 8 wherein each liquid barrier (115) comprises portions of the topsheet (111) and a further backsheet (112) of the upper napkin (110a) that are bonded together and folded over to extend upwardly with respect to the remaining portion of the backsheet (112) of the upper napkin (110a). The sanitary napkin claimed in any one of claims 5 to 9 wherein the lower napkin (110b) includes a liquid-absorbent core (214) sandwiched between a further topsheet (211) that is bonded to the backsheet of the lower napkin (110b).

Inventors: YAMAMOTO MASAMITSU, YAMAMOTO, MASAMITSU
Applicants: UNI CHARM CORP, UNI-CHARM CORPORATION
Application year: 1993
Main classification: A61F13
IPC codes: A61F13