Absorbent article with longitudinal elastic members

Abstract: An absorbent article including a liquid-retentive absorptive layer formed on a liquid-impermeable, leak-preventive layer in a substantially elongated configuration, the absorbent layer including a liquid-permeable top sheet and a liquid-retentive absorbent member, and the absorbent article is provided longitudinally with left and right opposite side portions containing elastic members which extend in the longitudinal direction thereof, wherein the elastic members are covered with an elastic member-attached sheet provided on an inner surface side of the top sheet.

Description: The present invention relates to an absorbent article as defined in the preamble of claim 1, such as a sanitary napkin or an incontinent pad. The absorbent article of the present invention renders no adverse effect to the skin of the user due to the oozing-out of an adhesive agent. The absorbent article is also superb in fitness and high in its leak-preventive effect. WO-A-97/09016 and EP-A-534 488 describe absorbent articles of the type as defined in the preamble of claim 1, having a topsheet, a backsheet and an absorbent member enclosed therebetween. The top and back sheets extend beyond the lateral sides of the absorbent member and are attached to each other in this region. The attachment region is covered by one or more separate sheets to form lateral cuffs which may include elastic means. The sheets are intended to make the cuffs compliant and soft to the skin. EP-A-219 326 describes an absorbent article having lateral cuffs. In one embodiment the cuffs contain absorbent material and are provided with elastic means. The elastic means are enclosed within a fold of the combined back and top layers which are extended beyond the absorbent member and which are attached to each other to form the cuffs. As an absorbent article such as a sanitary napkin and the like, there has heretofore been widely used one including a liquid-retentive absorptive layer and a liquid impermeable leak-preventive layer and formed in a substantially vertically elongated configuration. In such an absorbent article, the absorbent layer usually comprises a liquid-permeable top sheet and a liquid-retentive absorbent member. Recently, it has been proposed, in order to enhance the fitness and leak-preventive property, that the elastic members should each be disposed on opposite left and right side edge portions of the absorbent member. However, since it is the usual practice that the elastic member is adhered to the top sheet and the absorbent member through an adhesive agent directly applied to the elastic member, the conventional absorbent article such as a sanitary napkin and the like provided with such an elastic member has the shortcoming in that the adhesive agent oozes out to the top sheet to reach the surface of the top sheet where the adhesive agent contacts the skin of the wearer which degrades the perception of wearing. In a worst case, the adhesive agent even adversely affects the skin of the wearer. It is, therefore, an object of the present invention to provide an absorbent article which is superb in fitness and in absorbing ability and which renders no adverse effect to the skin of the wearer. The present inventors have discovered the fact that an absorbent article according to claim 1 comprising an elastic member covered with an elastic member-attached sheet provided with an elastic member can achieve the above object. The present invention provides an absorbent article including a liquid-retentive absorptive layer and a liquid-impermeable, leak-preventive layer and formed in a substantially vertically elongated configuration wherein the absorbent layer includes a liquid-permeable top sheet and a liquid-retentive absorbent member, and wherein the absorbent article is provided on longitudinal left and right opposite side portions thereof with elastic members extending in the longitudinal direction thereof, such that the elastic members are covered with an elastic member-attached sheet provided on the inner surface side of the top sheet The absorbent article of the present invention is superb in fitness and in absorbing ability and renders no adverse effect to the skin of the wearer. The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: Figure 1 is a perspective view showing a sanitary napkin as one embodiment of the absorbent article of the present invention; Figure 2 is a view taken along line II-II of Figure 1; and Figure 3 is an enlarged view of the portion indicated by III of Figure 2. The absorbent article of the present invention will now be described in detail with reference to the drawing. Figure 1 is a perspective view showing a sanitary napkin as one embodiment of the absorbent article of the present invention, and Figure 2 is a view taken along line II-II of Figure 1. Figure 3 is an enlarged view of a portion indicated by III of Figure 2. As shown in Figure 2, a leak-preventive layer 3 comprises a liquid-permeable sheet 31, a leak-preventive sheet 32 and an absorbent core 33 interposed between sheets 31 and 32. That is, the leak-preventive layer 3 is formed by sandwiching an absorbent core 33 composed of an absorptive sheet between the liquid-permeable sheet 31 and the leak-preventive sheet 32, and sealing the liquid-permeable sheet 31 and the leak-preventive sheet 32 at the peripheral edge portions of the absorbent core 33. An absorptive-layer 2 is placed on the liquid-permeable sheet 31 of the leak-preventive layer 3 and fixed thereto. This fixture is made by adhering left and right opposite side edge portions of the fixture portion 21 with an adhesive agent. The longitudinal opposite end edges of the absorptive-layer 2 and the leak-preventive layer 3 are fixedly heat sealed. The leak-preventive layer 3 is provided on its back side with an article fixture portion 34 for fixing the sanitary napkin, when in use, to a clothing member such as underwear or any standard undergarment. In this embodiment, the fixture portion 34 exhibits a strip-like configuration. Two such fixture portions 34 can be provided on the longitudinal left and right opposite side edges of the leak-preventive layer. As shown in Figures 1 and 2, a groove portion 26 is formed at the left and right opposite side edges of the fixture portion 21 so that the above-mentioned free edge portion 22 is more favorably erected or extended in the upward direction. As the adhesive agent for fixing the liquid-permeable sheet 31, the leak-preventive sheet 32 and the absorptive sheet as the absorbent core 33 constituting the leak-preventive layer 3, the elastic member 25, the absorptive-layer 2, and the viscous agent for forming the article fixture portion 34, those ordinarily used in an absorbent article such as a sanitary napkin can be used without any particular limitation. The absorptive-layer 2 includes a liquid-permeable top sheet 23 and a liquid-retentive absorbent member 24. The elastic member 25 is provided on longitudinal left and right opposite side portions of the sanitary napkin 1 along its longitudinal direction such that the elastic member 25 is covered with the top sheet 23 and an elastic member-attached sheet 28 disposed on the inner side (absorbent member side 24) of the top sheet 23. More specifically, the elastic member 25 is interposed between the absorbent member 24 and the top sheet 23 disposed in such a manner as to cover the absorbent member 24. The elastic member 25 is fixed to the elastic member-attached sheet 28 through an adhesive agent 29. The elastic member-attached sheet 28 is disposed in such a manner as to cover the absorbent member 24. It should be noted that the elastic member-attached sheet 28 is not required to cover the entire absorbent member 24, but it may cover only a part of the absorbent member 24 as long as the effect of attachment of the elastic member 25 can be obtained, and the elastic member 25 can be attached in such a manner that the adhesive agent will not ooze out. As shown in Figures 2 and 3, in the sanitary napkin 1 according to this embodiment, the absorptive-layer 2 is divided into the fixture portion 21 fixed to the leak-preventive layer 3 located on its widthwise central portion, and a pair of left and right free edge portions 22 located widthwise and extending outwardly of the fixture portion 21. The liquid-permeable top sheet 23 covers the outer surface of the liquid-retentive absorbent member 24 such that the absorbent member 24 is present widthwise over the entire area of the absorptive-layer 2. The elastic members 25 are disposed on the longitudinal left and right opposite side edge portions 24a of the absorbent member 24 along the longitudinal direction of the absorbent member 24 over a predetermined length thereof. The free edge portions 22 in the absorptive-layer 2 are extended upwardly of the leak-preventive layer 3 by contraction of the elastic members 25. As shown in Figure 2, the absorptive-layer 2 is covered by the top sheet 23 at its entire area, with the exception of the area abutting with the leak-preventive layer 3 of the absorbent member 24. In the absorptive-layer 2, a second absorbent member 27 is disposed on the fixture portion 21 between the top sheet 23 and the absorbent member 24. As material for forming the top sheet 23, those ordinarily used as a top sheet in an absorbent article such as a sanitary napkin can be used without any particular limitation. Preferably the top sheet 23 is formed of a perforated sheet having a bore share of 4 to 30%, a bore of 0.15 to 1.0 mm and composed of a linear low density polyethylene (L-LDPE), low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene, ethylene vinyl acetate (EVA), or blended polymers thereof In this embodiment, the absorbent member 24 is formed of an ordinary absorptive sheet (not shown). The elastic member 25 is disposed along an edge portion 24a of the absorbent member 24 on the back side of the absorbent member 24 at the free edge portion 22 and generally over the longitudinal entire area of the absorptive-layer 2. The elastic member 25 exhibits a strip-like configuration and is preferably 2 to 15 mm in width. As the elastic member 25, those ordinarily used for an absorbent article can be used without any particular limitation. Particularly preferred are elastic members composed of a foamed member of polyolefins or polyurethanes, or, alternatively, natural rubber can be used as the elastic member 25. The elastic member 25 can take the form of a string, a film, or any planar configured member. In this embodiment, a string-like elastic member is used. The number of the elastic members is not particularly limited. A plurality of elastic members may be provided instead of one each as in this embodiment. It is preferable that the elastic force of the elastic member is 100 g or less in stress at 20% expansion. The elastic member-attached sheets 28 are disposed in such a manner as to cover the elastic member 25 and also cover the front and back sides of the absorbent member 24 at the free edge portions 22. That is, the elastic member 25 is disposed such that one surface of the elastic member 25 contacts the absorbent member 24 and the other surface contacts the elastic member-attached sheets 28. The elastic member-attached sheets 28 cover the entire surface of the free edge portions 22 such that longitudinal left and right opposite side portions 28a, 28b thereof are located on the widthwise more central side than the groove portion 26. That is, the elastic member-attached sheets 28 are generally the same in configuration as the top sheet and located at the same position as the top sheet. As the material for forming the elastic member-attached sheets 28, those capable of preventing the adhesive agent from oozing out can be used without any particular limitation. However, in case the elastic member attached sheets 28 are disposed in such a manner as to cover the front side (skin-contact surface side) of the absorbent member 24 located on the free edge portions 22 as in this embodiment, they are required to be liquid-permeable sheets. AS sheets usable as material for forming the elastic member-attached sheets 28, those ordinarily used as a top sheet can be used without any limitation. Examples of such sheets include those obtained by forming a liquid-impermeable film composed of the above-mentioned material in the form of a net using perforated film and a thermoplastic resin, and the below-listed nonwoven fabric. In view of rigidity, nonwoven fabric is preferably used. In this embodiment, the elastic member-attached sheets 28 are each formed of a nonwoven fabric. Nonwoven fabrics are obtained by twisting or adhering fibers together. Particularly preferable in view of flexibility and the sense of touch and outlook is the so-called dried heat-adhered nonwoven fabric obtained by fixing the fibers together by heat welding. As the fiber composition of the nonwoven fabric, polyolefins, polyesters, acrylics, polyamides, or the like can be freely used. Particularly, preferable composite fibers of polyethylene/polyesters, polyethylene/polypropylenes or polyethylene/polyethylenes can be used in view of the sense of touch, outlook and strength. The basic weight of the nonwoven fabric used as the material for forming the elastic member-attached sheet is preferably 10 to 30 g/m 2 . The fineness of the composite fibers of the nonwoven fabric is preferably 1.5 to 15d. In case the elastic member-attached sheets 28 are disposed not in such a manner as to cover the absorbent member 24, for example, in case the absorbent member 24 is not present at the free edge portions 22, an ordinary liquid-impermeable sheet may also be used as the elastic member-attached sheet 28. The sanitary napkin of this embodiment is such that the adhesive agent used for fixing the elastic members will not ooze out of the surface of the absorptive-layer and therefore the perception of wearing is not degraded, and no adverse effect is given to the skin of the wearer. For the above reasons, the adhesive agent employed in this embodiment can be selected from a wide range of adhesive agents. Specifically, in the sanitary napkin of this embodiment, the adhesive agent for fixing the elastic member can be freely selected from hot melt viscous agents based on styrene, natural rubber, olefins, polyisobutylene, or the like. Since the adhesive agent of this type rarely oozes out to the top side, the material may be of the type ranging from a low melting point of about 90°C. to a high melting point of about 230°C. With respect to the basic weight of the coating of the adhesive agent, in the case where the adhesive agent is applied directly to the top material, the upper limit is several g/m 2 , but in this embodiment, the adhesive agent can be applied in a large amount of about several tens of g/m 2 maximum in order to ensure strength of viscosity. In order to fix the elastic members 25 to the elastic member-attached sheets 28, the basic weight of the adhesive agent to be applied is effective 3 to 25 g/m 2 and particularly, preferably 5 to 18 g/m 2 , from the viewpoint of adhesive property and the perception of use of the fixed portion. As described above, since the absorptive-layer 2 is not fixed directly to undergarments or the like but only through the leak-preventive layer 3, the leak-preventive layer 3 follows the motion of the undergarments, etc. but the absorptive-layer 2 does not, and therefore the effect of motion by the wearer is small. Accordingly, the shape of the absorptive-layer 2 rarely collapses and thus it is superb in fitness. Particularly, in the case where the width of the article fixture portion 34 is larger than the width of the fixture portion 21, a particularly effective result can be exhibited because the ratio of the leak-preventive layer 3 following the motion of the wearer can be greatly reduced. Moreover, since the absorbent member 24 is present up to the wide edges of the absorptive-layer 2, the above arrangement is particularly superior in its side leakage-preventive property. The sanitary napkin of this embodiment can be manufactured as follows. After the elastic member 25 is adhered to the elastic member-attached sheets 28 through an adhesive agent, the elastic member-attached sheets 28 are disposed in such a manner as to cover the top side of the absorbent member 24 located on the fixture portion and the entire absorbent member 24 located on the free edge portion 22. Then, the entirety is covered with the top sheet 23 to form the absorptive-layer 2. Then, after the leak-preventive layer 3 is formed separately, the absorptive-layer 2 and the leak-preventive layer 3 are fixed together using an adhesive agent. It should be noted, however, that the present invention is not limited to the above-mentioned manufacturing method. It should be noted that the absorbent article of the present invention is not limited to the above-mentioned embodiments and that a wide range of modifications can be made without departing from the scope of the present invention. For example, in the embodiment of Figures 1 to 3, the leak-preventive layer 3 is acceptable even if it does not include the absorbent core 33. The leak-preventive layer 3 may be designed such that the leak-preventive sheet is disposed on the back of the absorbent member and the leak-preventive sheet is covered with the top sheet. In the absorbent article of the present invention, the whole absorptive layer may be provided with the leak-preventive layer, without dividing the absorptive-layer into the fixture portion 21 and the free edge portions 22.

Claims: An absorbent article (1) including a liquid-retentive absorptive layer (2) arranged on a liquid-impermeable, leak-preventive layer (3) in a substantially elongated configuration, said absorptive layer (2) including a liquid-permeable top sheet (23) and a liquid-retentive absorbent member (24), wherein said absorbent article (1) is provided on longitudinal left and right opposite side portions thereof with elastic members (25) which extend in the longitudinal direction thereof, said elastic member (25) being covered with a sheet (28) disposed on the inner surface side of said top sheet (23), characterised In that said sheet is an elastic member attached sheet (28), said absorbent member (24) includes a free edge portion (22), provided with said elastic member (25), said elastic member-attached sheet (28) is disposed in such a manner as to cover front and back sides of said free edge portion (22) of said absorbent member (24), and said elastic member (25) is fixed to said elastic member-attached sheet (28) by an adhesive agent (29), with one surface of the elastic member (25) contacting the absorbent member (24) and the other surface contacting the elastic member-attached sheet (28). The absorbent article according to claim 1, wherein said absorptive layer (2) has a central fixture portion (21) and lateral side portions. The absorbent article according to claim 1, wherein said elastic member-attached sheet (28) is formed of a nonwoven fabric. The absorbent article of claim 2, wherein the lateral side portions define said left and right free edge portions (22) which extend outwardly and upwardly from said centrally disposed fixture portion (21) due to the contraction of the elastic members (25). The absorbent article of claim 2, wherein the lateral side portions are extensions of the central fixture portion (21). The absorbent article of claim 2, wherein lateral side portions are independent of the central fixture portion (21).

Inventors: HAMAJIMA MITSUGU, KAMEO YOJI, NAKAYAMA TAKAO, TANAKA MASAHITO, HAMAJIMA, MITSUGU, KAMEO, YOJI, NAKAYAMA, TAKAO, TANAKA, MASAHITO, Hamajima, Mitsugu, c/o Kao Corporation, Kameo, Yoji, c/o Kao Corporation, Nakayama, Takao, c/o Kao Corporation, Tanaka, Masahito, c/o Kao Corporation
Applicants: KAO CORP, KAO CORPORATION
Application year: 1998
Main classification: A61F13
IPC codes: A61F13