Pull-on disposable diaper

Abstract: A pull-on disposable diaper 1 is provided, in vicinity of transversely opposite side edges 1a, 1b in a rear waist region 32, with fastening tape strips 12 adapted to hold the diaper 1 in its rolled up state for disposal after the diaper 1 has been used, each of the tape strips 12 includes a first portion 12a extending longitudinally of the diaper 1 parallel to the associated one of transversely opposite side edges 1a, 1b and a second portion 12b branched from the first portion 12a and extends longitudinally of the diaper 1, longitudinally opposite end regions 12a 1 of the first portion 12a are bonded to edges 8, 9 of waist- and leg-openings 6, 7, and an anchoring zone adapted to be separably anchored on the outer peripheral surface of the rolled up diaper 1 is defined on the second portion 12b.

Description: This invention relates to a pull-on disposable diaper provided with fastening tape to fasten the diaper in its rolled up state for disposal after diaper has been used. Japanese Patent Publication A No. 1997-253123 describes a disposable diaper comprising a topsheet, a backsheet and an absorbent core disposed between these two sheets so as to configure a front waist region, a rear waist region and a crotch region extending between these two waist regions. The front or rear waist region is provided on the outer surface of the backsheet with a single strip of fastening tape adapted to secure the used diaper in its rolled up state for disposal. More specifically, the strip of fastening tape extends circumferentially of the diaper and has its longitudinally middle portion fixed to the diaper and its longitudinally opposite end portions folded up so that these end portions may be unfolded when it is desired to use this strip of fastening tape. The longitudinally opposite end portions are coated with pressure-sensitive adhesive by means of which these end portions are maintained in folded up state. Japanese Patent Publication A No. 1997-253124 describes a disposable diaper comprising a topsheet, a backsheet and an absorbent core disposed between these two sheets so as to configure a front waist region, a rear waist region and a crotch region extending between these two waist region. The front or rear waist region is provided on the outer surface of the backsheet with fastening tape adapted to secure the used diaper in its rolled up state for disposal. In this diaper of prior art, the fastening tape comprises at least two strips of adhesive tape extending in parallel to each other circumferentially of the diaper. For disposal, these diapers of prior art are similar to each other in that the strip(s) of fastening tape is or are wound around the outer peripheral surface of the diaper which has been used and rolled up from its transversely opposite side edges and fixed to the outer peripheral surface of the used diaper. Certainly, it is possible for these diapers described in the above-mentioned Publication to hold the used diaper in its rolled up state by secure the rolled up diaper substantially at a middle level of the diaper. However, it is impossible for these diapers to close the waist-opening of the diaper utilizing the strip(s) of fastening tape. Even after the used diaper has tightly been rolled up from its transversely opposite side edges, the waist-opening remains free and it is concerned that excretion itself or its odor might leak through the waist-opening. It is an object of this invention to provide a pull-on disposable diaper adapted to be held in its rolled up state for disposal without any anxiety that excretion itself or its odor might leak through the waist-opening and/or the leg-openings. According to this invention, there is provided a pull-on disposable diaper comprising a liquid-pervious topsheet, a liquid-impervious backsheet and a liquid-absorbent core disposed between the topsheet and the backsheet to define a front waist region, a rear waist region and a crotch region extending between the front and rear waist regions, the front and rear waist regions being placed upon each other with the topsheet inside along transversely opposite side edges of the diaper to define a waist-opening and a pair of leg-openings wherein the waist-opening and the leg-openings have an elastic stretchability circumferentially thereof, and the diaper being provided on an outer surface of the backsheet with fastening tape strips adapted to hold the diaper in a rolled up state thereof for disposal after the diaper has been used. This invention further comprises the fastening tape strips are provided in vicinity of the transversely opposite side edges at least one of the front and rear waist regions, each of the fastening tape strips being formed by a first portion extending in parallel to the side edges longitudinally of the diaper and a second portion extending from a predetermined region of the first portion longitudinally or transversely of the diaper, the first portion having longitudinally opposite end regions thereof bonded to the diaper in vicinity of an edge of the waist-opening and in vicinity of an edge of the leg-opening so that at least one of an intermediate region extending between the longitudinally opposite end regions of the first portion and the second portion defines an anchoring zone adapted to be separably anchored on an outer peripheral surface of the rolled up diaper. In the pull-on disposable diaper according to this invention, the respective first portions of the fastening tape strips have their longitudinally opposite ends are secured to the respective peripheral edges of the waist- and leg-openings in contiguousness to the elastic members secured under tension to the respective peripheral edges of the waist- and leg-openings so that the respective elastic members may be stretched outward transversely of the diaper as the respective fastening tape strips are pulled outward transversely of the diaper. The fastening tape strips wound and anchored on the outer peripheral surface of the rolled up diaper well hold the diaper in its rolled up state and tensile force generated in the respective elastic members maintains the waist-opening and the leg-openings in closed state. As a result, there is no anxiety that these openings might be loosen and excretion or its odor might leak through these openings. With the embodiment of the diaper in which the fastening tape strips extend to describe curves which are convex outward transversely of the diaper, the fastening tape strips can be anchored on the outer peripheral surface of the diaper more firmly than the fastening tape strips extending rectilinearly. In this way, it is avoided that the fastening tape strips anchored on the outer peripheral surface of the diaper might be unintentionally peeled off therefrom. With the embodiment of the diaper in which the second portions of the respective fastening tape strips extend outward from the intermediate regions of the first portions and folded back so that they may be unfolded outward transversely of the diaper after the diaper has been used, the second portions do not extend outward transversely of the diaper before and during actual use of the diaper. In this way, the fastening tape strips can be provided in the vicinity of the side edges of the diaper and the second portions do not obstruct handling of the diaper. Fig. 1 is a perspective view depicting one embodiment of a partially cutaway pull-on disposable diaper according to this invention as viewed from a rear waist region side; Fig. 2 is a sectional view taken along line A - A in Fig. 1; Fig. 3 is a perspective view depicting the diaper of Fig. 1 as rolled up for disposal; Fig. 4 is a view similar to Fig. 1 depicting another embodiment of the diaper as viewed from the rear waist region side; Fig. 5 is a sectional view taken along line B - B in Fig. 4; Fig. 6 is a view similar to Fig. 3 depicting the diaper of Fig. 4 as rolled up for disposal; Fig. 7 is a view similar to Fig. 1 depicting still another embodiment of the diaper as viewed from the rear waist region side; Fig. 8 is a sectional view taken along line C - C in Fig. 7; Fig. 9 is a sectional view taken along line D - D in Fig. 7; Fig. 10 is a view similar to Fig. 3 depicting the diaper of Fig. 7 as rolled up for disposal; Fig. 11 is a view similar to Fig. 1 depicting further another embodiment of the diaper as viewed from the rear waist region side; Fig. 12 is a sectional view taken along line E - E in Fig. 11; Fig. 13 is a sectional view taken along line F - F in Fig. 11; and Fig. 14 is a view similar to Fig. 3 depicting the diaper of Fig. 11 as rolled up for disposal. Details of a pull-on disposable diaper according to this invention will be more fully understood from the description given hereunder with reference to the accompanying drawings. Fig. 1 is a perspective view depicting one embodiment of a pull-on disposable diaper 1 according to this invention as viewed from the side of a rear waist region and Fig. 2 is a sectional view taken along line A - A in Fig. 1. Referring to Fig. 1, one of fastening tape strips 12 is illustrated as it has been peeled off from a release sheet 15 as indicated by chain lines. The diaper 1 basically comprises a liquid-pervious topsheet 2, a liquid-impervious backsheet 3 and a liquid-absorbent core 4 disposed between the topsheet 2 and the backsheet 3 and entirely covered with and bonded to a water-pervious tissue paper 5. The tissue paper 5 is bonded to the inner surface of at least one of the topsheet 2 and the backsheet 3. The diaper 1 is longitudinally configured by a front waist region 30, a rear waist region 32 and a crotch region 31 extending between the front and rear waist regions 30, 32. In this diaper 1, transversely opposite side edges 1a, 1b longitudinally extending in the front and rear waist regions 30, 32, respectively, are put flat together and bonded together to define a waist-opening 6 and a pair of leg-openings 7. A plurality of elastically stretchable members 10 extend entirely along a peripheral edge 8 of the waist-opening 6 between the topsheet 2 and the backsheet 3 and are secured under tension to the inner surface of at least one of the topsheet 2 and the backsheet 3. Similarly, a plurality of elastically stretchable members 11 extend entirely along a peripheral edge 9 of each leg-opening 7 between the topsheet 2 and the backsheet 3 and are secured under tension to the inner surface of at least one of the topsheet 2 and the backsheet 3. In the diaper 1, the respective peripheral edges 8, 9 of the waist-opening 6 and the leg-openings 7 have an elastic stretchability circumferentially of these openings 6, 7. In the state shown by Fig. 1, the elastic members 10, 11 have been relieved of the tension and a plurality of gathers are formed along the respective peripheral edges 8, 9 of the waist-opening 6 and the leg-openings 7. In the vicinity of the transversely opposite side edges 1a, 1b of the rear waist region 32, the backsheet 3 is provided on its outer surface with a pair of fastening tape strips 12 used to hold the used diaper 1 in its rolled up state for disposal. These fastening tape strips 12 are formed by flexible but non-stretchable plastic sheets each comprising a first portion 12a longitudinally extending in parallel to the side edge 1a, 1b and a second portion 12b branched from the outer surface of the first portion 12a and extending in parallel to the first portion 12a toward the peripheral edge 8 of the waist-opening 6. The first portion 12a has longitudinally opposite end regions 12a 2 and an intermediate region 12a 1 extending between the longitudinally opposite end regions 12a 2 . The longitudinally opposite end regions 12a 2 of the first portion 12a are contiguous to the elastic members 10, 11 which are, in turn, attached to the respective peripheral edges 8, 9 of the waist-opening 6 and the leg-openings 7, respectively, and bonded to the outer surface of the backsheet 3 by means of adhesive 14. While the longitudinally opposite end regions 12a 2 are preferably contiguous to two or more of the elastic members 10, 11 respectively associated with the waist-opening 6 and the leg-openings 7, it suffices that these end regions 12a 2 are contiguous to at least one of these elastic members 10, 11, respectively. The first portion 12a is provided on its outer surface with a plastic release sheet 15 extending from the intermediate region 12a 1 to one of the end regions 12a 2 and firmly bonded to the outer surface by means of adhesive 16. The second portion 12b is branched from the intermediate region 12a 1 of the first portion 12a and has a fixed proximal end region 12b 2 bonded to the outer surface of the first portion 12a by means of adhesive 17 and a free end region 12b 1 of which the inner surface is coated with pressure-sensitive adhesive 18. The free end region 12b 1 of the second portion 12b is separably bonded to the release sheet 15 by means of the pressure-sensitive adhesive 18. A distal end region of the second portion 12b free from coating of pressure-sensitive adhesive defines a handling tip 13. Of the fastening tape strip 12, the free end region 12b 1 of the second portion 12b is destined to be separably anchored on the outer surface of the backsheet 3 after the used diaper 1 has been rolled up for disposal. The state of the fastening tape strip 12 is changed to the state indicated by chain lines in Fig. 1 as the free end region 12b 1 of the second portion 12b is peeled off from the release sheet 15. Both the intermediate region 12a 1 of the first portion 12a and the free end region 12b 1 of the second portion 12b are deformable, e.g., flexible and twistable. Fig. 3 is a perspective view depicting the diaper 1 of Fig. 1 as rolled up for disposal. The diaper 1 is longitudinally rolled up from the crotch region 31 toward the waist-opening 6 with the front waist region 30 inside and the waist-opening 6 outside the rolled up. The first portion 12a and the second portion 12b extending transversely of the diaper 1 are wound around the outer peripheral surface of the rolled up diaper 1 and the free end region 12b 1 of the second portion 12b is anchored on the outer surface of the backsheet 3 by means of pressure-sensitive adhesive 18. Referring to Fig. 3, the respective peripheral edges 8, 9 of the waist-opening 6 and the leg-openings 7 are partially folded inward transversely of the diaper 1. To fasten the rolled up diaper 1 by the fastening tape strip 12, the second portion 12b is peeled off from the release sheet 18 with the handling tip 13 held by fingers and then the free end region 12b 1 of the second portion 12b is pressed against the outer surface of the backsheet 3 with the fastening tape strip 12 being pulled outward transversely of the diaper 1. The elastic members 10 associated with the waist-opening and the elastic members 11 associated with the leg-openings to which the longitudinally opposite end regions 12a 2 of the respective first portions 12a are stretched outward transversely of the diaper 1 as the respective fastening tape strips 12 are pulled outward transversely of the diaper 1. Tensile force generated in the respective elastic members 10, 11 stretched in this manner places the respective peripheral edges 8, 9 of these openings 6, 7 under tension and thereby tends to close these openings 6, 7. In this way, the used diaper 1 is held by the respective fastening tape strips 12 in its rolled up state and at the same time the waist-opening 6 and the leg-openings 7 are closed under the tensile force generated in the respective elastic members 10, 11. Accordingly, there is no anxiety that these openings 6, 7 might be loosen and excretion or its odor might leak through these openings 6, 7. Fig. 4 is a view similar to Fig. 1 depicting another embodiment of the diaper 1 as viewed from the side of the rear waist region 32 and Fig. 5 is a sectional view taken along line B - B in Fig. 4. Referring to Fig. 1, one of fastening tape strips 12 is illustrated as it has been peeled off from release sheets 15, 20 as indicated by imaginary line. The diaper 1 basically comprises a liquid-pervious topsheet 2, a liquid-impervious backsheet 3 and a liquid-absorbent core 4 disposed between the topsheet 2 and the backsheet 3 and covered with and bonded to a water-pervious tissue paper 5. In this diaper 1, transversely opposite side edges 1a, 1b in the front and rear waist regions 30, 32, respectively, are put flat together and firmly bonded together to define a waist-opening 6 and a pair of leg-openings 7. A plurality of elastic members 10 are secured under tension to the waist-opening 6 along its peripheral edge 8 and a plurality of elastic members 11 are secured under tension to the leg-openings 7 entirely along their peripheral edges 9. In the vicinity of the transversely opposite side edges 1a, 1b of the rear waist region 32, the backsheet 3 is provided on its outer surface with a pair of fastening tape strips 12. These fastening tape strips 12 are formed by flexible but non-stretchable plastic sheets each comprising a first portion 12a longitudinally extending in parallel to the side edge 1a, 1b and a second portion 12b branched from the outer surface of the first portion 12a and extending in parallel to the first portion 12a toward the peripheral edge 9 of the leg-openings 7. The first portion 12a has longitudinally opposite end regions 12a 2 and an intermediate region 12a 1 extending to describe a curve which is convex outward transversely of the diaper 1. The longitudinally opposite end regions 12a 2 of the first portion 12a are contiguous to the elastic members 10, 11 which are, in turn, attached to the respective peripheral edges 8, 9 of the waist-opening 6 and the leg-openings 7, respectively, and bonded to the outer surface of the backsheet 3 by means of adhesive 14. The first portion 12a is provided on its outer surface with a plastic release sheet 15 extending from the intermediate region 12a 1 to one of the end regions 12a 2 and bonded to the outer surface by means of adhesive 16. The intermediate region 12a 1 of the first portion 12a is coated on its inner surface with pressure-sensitive adhesive 19. A release sheet 20 is bonded to the outer surface of the backsheet 3 by means of adhesive 21 so that the intermediate region 12a 1 of the first portion 12a may be separably bonded to the release sheet 20 by means of pressure-sensitive adhesive 19. The second portion 12b is branched from the intermediate region 12a 1 of the first portion 12a and has a fixed proximal end region 12b 2 bonded to the outer surface of the first portion 12a by means of adhesive 17 and a free end region 12b 1 of which the inner surface is coated with pressure-sensitive adhesive 18. The free end region 12b 1 of the second portion 12b is separably bonded to the release sheet 15 by means of the pressure-sensitive adhesive 18. A distal end region of the second portion 12b free from coating of pressure-sensitive adhesive defines a handling tip 13. Of the fastening tape strip 12, the intermediate region 12a 1 of the first portion 12a and the free end region 12b 1 of the second portion 12b are destined to be separably anchored on the outer surface of the backsheet 3 after the used diaper 1 has been rolled up for disposal. Fig. 6 is a perspective view depicting the diaper 1 of Fig. 4 as rolled up for disposal. The diaper 1 is rolled up from the crotch region 31 toward the waist-opening 6 with the waist-opening 6 lying outside the rolled up. The first portion 12a and the second portion 12b extending transversely of the diaper 1 are wound around the outer peripheral surface of the rolled up diaper 1. Thereupon, the intermediate 12a 1 of the first portion 12a and the free end region 12b 1 of the second portion 12b have their inner surfaces anchored on the outer surface eof the backsheet 3 by means of pressure-sensitive adhesive 18, 19, respectively. A tensile force generated in the respective elastic members 10, 11 maintains the waist-opening 6 and the leg-openings 7 in closed state and there is no anxiety that these openings 6, 7 might be loosen and excretion or its odor might leak through these openings 6, 7. The intermediate region 12a 1 of the first portion 12a and the free end region 12b 1 of the second portion 12b are destined to be anchored on the backsheet's outer surface of the rolled up diaper 1. The unique arrangement that the first portion 12a extend so as to describe a curve which is convex outward transversely of the diaper 1 enables the intermediate region 12a 1 of the first portion 12a to be anchored on the outer surface of the backsheet 3 more reliably than the case in which the intermediate region 12a 1 is not coated with pressure-sensitive adhesive or the first portion 12a is rectilinear. Consequently, it is avoided that the fastening tape strips 12 once anchored on the outer surface of the backsheet 3 might be unintentionally peeled off therefrom. Fig. 7 is a perspective view depicting another embodiment of the diaper 1 as viewed from the side of the rear waist region 32, Fig. 8 is a sectional view taken along line C - C in Fig. 7 and Fig. 9 is a sectional view taken along line D - D in Fig. 7. Referring to Fig. 7, one of fastening tape strips 12 is illustrated as it has been peeled off from release sheet 20, as indicated by imaginary line. The diaper 1 basically comprises a liquid-pervious topsheet 2, a liquid-impervious backsheet 3 and a liquid-absorbent core 4 disposed between the top- and backsheets 2, 3 and covered with and bonded to a water-pervious tissue paper 5. In this diaper 1, transversely opposite side edges 1a, 1b in the front and rear waist regions 30, 32, respectively, are put flat together and bonded together to define a waist-opening 6 and a pair of leg-openings 7. A plurality of elastic members 10 are secured under tension to the waist-opening 6 along its entire peripheral edge 8 and a plurality of elastic members 11 are secured under tension to the leg-openings 7 along their entire peripheral edges 9. In the vicinity of the transversely opposite side edges 1a, 1b of the rear waist region 32, the backsheet 3 is provided on its outer surface with a pair of fastening tape strips 12, 13. These fastening tape strips 12 are formed by flexible but non-stretchable plastic sheets each comprising a first portion 12a longitudinally extending in parallel to the side edge 1a, 1b of the diaper 1 and a second portion 12b branched from said first portion 12a. The first portion 12a has longitudinally opposite end regions 12a 2 and an intermediate region 12a 1 extending to describe a curve which is convex outward transversely of the diaper 1. The longitudinally opposite end regions 12a 2 of the first portion 12a are contiguous to the elastic members 10, 11 which are, in turn, secured to the respective peripheral edges 8, 9 of the waist-opening 6 and the leg-openings 7, respectively, and bonded to the outer surface of the backsheet 3 by means of adhesive 14. The second portion 12b extends outward transversely of the diaper 1 from the intermediate region 12a 1 of the first portion 12a. The intermediate region 12a 1 of the first portion 12b and the second portion 12b have their inner surfaces coated with pressure-sensitive adhesive 19. The release sheet 20 made of plastic material is bonded to the outer surface of the backsheet 3 by means of adhesive 21 so that the intermediate region 12a 1 of the first portion 12b and the second portion 12b may be separably bonded to the release sheet 20. In this manner, the intermediate region 12a 1 of the first portion 12b and the second portion 12b have their inner surfaces separably bonded to the release sheet 20 by means of the pressure-sensitive adhesive 19. A distal end region of the second portion 12b free from coating of pressure-sensitive adhesive defines a handling tip 13. Fig. 10 is a perspective view depicting the diaper 1 of Fig. 7 as rolled up for disposal. The diaper 1 is longitudinally rolled up from the crotch region 31 toward the waist-opening 6 with the waist-opening 6 lying outside the rolled up. The first portion 12a and the second portion 12b extending transversely of the diaper 1 are wound around the outer peripheral surface of the rolled up diaper 1. Thereupon, the intermediate 12a 1 of the first portion 12b and the second portion 12b have their inner surfaces anchored on the outer surface of the backsheet 3 by means of pressure-sensitive adhesive 19. A tensile force generated in the respective elastic members 10, 11 maintains the waist-opening 6 and the leg-openings 7 in closed state and there is no anxiety that these openings 6, 7 might be loosen and excretion or its odor might leak through these openings 6, 7. Fig. 11 is a perspective view depicting another embodiment of the diaper 1 as viewed from the side of the rear waist region 32, Fig. 12 is a sectional view taken along line E - E in Fig. 11 and Fig. 13 is a sectional view taken along line F - F in Fig. 11. Referring to Fig. 11, one of fastening tape strips 12 is illustrated as its second portion 12b transversely unfolded as indicated by imaginary line. The diaper 1 basically comprises a liquid-pervious topsheet 2, a liquid-impervious backsheet 3 and a liquid-absorbent core 4 disposed between the topsheet 2 and the backsheet 3 and covered with and bonded to a water-pervious tissue paper 5. In this diaper 1, transversely opposite side edges 1a, 1b in the front and rear waist regions 30, 32, respectively, are put flat together and bonded together to define a waist-opening 6 and a pair of leg-openings 7. A plurality of elastic members 10 are secured under tension to the waist-opening 6 along its entire peripheral edge 8 in the rear waist region 32 and a plurality of elastic members 11 are secured under tension to the leg-openings 7 along their entire peripheral edges 9. In the vicinity of the transversely opposite side edges 1a, 1b of the rear waist region 32, the backsheet 3 is provided on its outer surface with a pair of fastening tape strips 12, 13. These fastening tape strips 12, 13 are formed by flexible but non-stretchable plastic sheets each comprising a first portion 12a longitudinally extending in parallel to the side edge 1a, 1b of the diaper 1 and a second portion 12b branched from the first portion 12a. The first portion 12a has longitudinally opposite end regions 12a 2 and an intermediate region 12a 1 . The longitudinally opposite end regions 12a 2 of the first portion 12a are contiguous to the elastic members 10, 11 which are, in turn, attached to the respective peripheral edges 8, 9 of the waist-opening 6 and the leg-openings 7, respectively, and bonded to the outer surface of the backsheet 3 by means of adhesive 14. As indicated by chain lines in Fig. 11, the second portion 12b extends outward transversely of the diaper 1 from the intermediate region 12a 1 of the first portion 12a. The second portion 12b is folded back in two in a manner that it may be unfolded outward transversely of the diaper 1. The second portion 12b is coated in desired zones on its inner and outer surfaces with pressure-sensitive adhesive 19 so that the second portion 12b may be held in its folded state by means of the pressure-sensitive adhesive 19. The surface of the second portion 12b destined to be opposed to the pressure-sensitive adhesive 19 as the second portion 12b is folded back has previously been subjected to an appropriate surface treatment in order that the second portion 12b can be easily unfolded. A distal end region of the second portion 12b free from coating of pressure-sensitive adhesive defines a handling tip 13. The second portion 12b of the fastening tape strip 12 may be pulled outward transversely of the diaper 1 with the handling tip 13 held by fingers to unfold the second portion 12b outward transversely of the diaper 1. Fig. 14 is a perspective view depicting the diaper 1 of Fig. 11 as rolled up for disposal. The diaper 1 is longitudinally rolled up from the crotch region 31 toward the waist-opening 6 with the waist-opening 6 lying outside the rolled up. The first portion 12a and the second portion 12b extending transversely of the diaper 1 are wound around the outer peripheral surface of the rolled up diaper 1. Thereupon, the second portion 12b has its inner surface anchored on the outer surface of the backsheet 3 by means of pressure-sensitive adhesive 19. A tensile force generated in the respective elastic members 10, 11 maintains the waist-opening 6 and the leg-openings 7 in closed state and there is no anxiety that these openings 6, 7 might be loosen and excretion or its odor might leak through these openings 6, 7. The respective second portions 12b are maintained to be folded back in two, respectively, before and during actual use of the diaper 1 and therefore it is not concerned that the handling convenience as well as the appearance of the diaper might be deteriorated by the second portions 12b extending outward transversely of the diaper 1. The topsheet 2 may be formed by a liquid-pervious sheet such as a nonwoven fabric or porous plastic film, preferably by a liquid-pervious hydrophilic sheet. The backsheet 3 may be formed by a hydrophobic nonwoven fabric, a liquid-impervious plastic film or a laminated sheet consisting of a hydrophobic nonwoven fabric and a plastic film, preferably by a breathable liquid-impervious sheet. It is also possible to form the backsheet 3 using composite a nonwoven fabric (SMS nonwoven fabric) comprising a sheet of melt blown nonwoven fabric being high in water resistance and two sheets of a spun bond nonwoven fabric being high in strength as well as in flexibility so that opposite sheet surfaces of the melt blown nonwoven fabric may be sandwiched between the respective sheet surfaces of the spun bond nonwoven fabric. The nonwoven fabric may be selected from a group including a spun lace nonwoven fabric, a needle punch nonwoven fabric, a melt blown nonwoven fabric, a thermal bond nonwoven fabric, a spun bond nonwoven fabric and a chemical bond nonwoven fabric. Component fiber of the nonwoven fabric may be selected from a group including polyolefine fiber, polyester fiber, polyamide fiber or conjugated fiber, for example, polyethylene/polypropylene or polyester conjugated fiber. The core 4 is a mixture of fluff pulp and high absorption polymer particles compressed to a desired thickness. Bonding or attaching of the core 4, the sheets 2, 3, 15, 20, the tape strips 12 and the elastic members 10, 11 may be carried out using suitable adhesive such as hot melt adhesive or pressure-sensitive adhesive or heat-sealing technique. The fastening tape strip 12 may be formed by an inelastic plastic sheet, elastomer such as synthetic or natural rubber having a certain degree of elastic stretchability or nonwoven fabric to which such elastomer has been secured under tension. In the case of the stretchable fastening tape strip 12, tensile force generated in the elastic members 10, 11 associated with the waist-opening and the leg-openings, respectively, cooperate with tensile force generated in the fastening tape strip 12 to improve the effect under which the waist-opening 6 and the leg-openings 7 can be held in closed state. It is possible without departing from the scope of this invention to attach the fastening tape strips 12 to the side edges 1a, 1b of the front waist region 30, respectively. It is also possible to attach one of these fastening tape strips 12 to one side edge 1a of the diaper 1 in the rear waist region 32 and to attach the other fastening tape strip 12 to the other side edge 1b of the diaper 1 in the front waist region 30. It is possible to dispose the longitudinally opposite end regions 12a 2 of the first portion 12a between the backsheet 3 and the tissue paper 5 and to bond them to at least one of the backsheet 3 and the tissue paper 5. While the elastic members 10 associated with the waist-opening may be secured under tension to the diaper 1 along the peripheral edge 8 of the waist-opening 6 at least one of the front and rear waist regions 30, 32, it is essential for the fastening tape strips 12 to be provided in the vicinity of the side edges 1a, 1b in the waist region provided with the elastic members 10 associated with the waist-opening 6. In the case of the backsheet 3 formed by a nonwoven fabric, it is also possible to provide the fastening tape strips 12 with hook members instead of being coated with pressure-sensitive adhesive so that the hook members are engaged with fibers of the nonwoven fabric to anchor the fastening tape strips 12 on the outer surface of the backsheet 3. when such hook members are used, the loop members may be used in the place of the release sheets.

Claims: A disposable diaper (1) of pants-type comprising a liquid-pervious topsheet (2), a liquid-impervious backsheet (3) and a liquid-absorbent core (4) disposed between said topsheet and said backsheet to define a front waist region (30), a rear waist region (32) and a crotch region (31) extending between said front and rear waist regions, said front and rear waist regions being placed upon each other with said topsheet inside along transversely opposite side edges (1a, 1b) of said diaper to define a waist-opening (6) and a pair of leg-openings (7) wherein said waist-opening and said leg-openings have an elastic stretchability circumferentially thereof, and said diaper being provided on an outer surface of said backsheet with fastening tape strips (12) adapted to hold said diaper in a rolled up state thereof for disposable after said diaper has been used, said diaper further comprising said fastening tape strips (12) being provided in vicinity of said transversely opposite side edges (1a, 1b) at least one of said front and rear waist regions, characterised in each of said fastening tape strips being formed by a first portion (12a) extending in parallel to said side edges longitudinally of said diaper and a second portion (12b) branched from a predetermined region (12a 1 ) of said first portion longitudinally or transversely of said diaper, said first portion (12a) having longitudinally opposite end regions (12a 2 ) thereof bonded to said diaper in vicinity of an edge of said waist-opening (6) and in vicinity of an edge of said leg-opening (7) so that at least one of an intermediate region extending between said longitudinally opposite end regions (12a 2 ) of said first portion (12a) and said second portion (12b) defines an anchoring zone (12b1) adapted to be separably anchored on an outer peripheral surface of said rolled up diaper. The diaper according to Claim 1, wherein said second portion (12b) is branched from an outer surface of said first portion at the intermediate region (12a 1 ) thereof and extends in parallel to said first portion toward the edge of said waist-opening or leg-openings so that said anchoring zone (12b 1 ) is defined on a surface of said second portion opposed to the outer surface of said first portion and separably bonded to the outer surface of said first portion by said anchoring zone. The diaper according to Claim 1, wherein said anchoring zone is defined on the inner surface of an intermediate region (12a 1 ) in said first portion and said inner surface of the intermediate region in said first portion is separably bonded to the outer surface of said backsheet (3) in vicinity of the associated one of said side edges (1a, 1b). The diaper according to Claim 1, wherein said second portion (12b) is branched from the intermediate region (12a 1 ) of said first portion and extends outward transversely of the diaper and said anchoring zone is defined on at least one of the inner surface of the intermediate region in said first portion and the inner surface of said second portion so that the inner surface of at least one of said first portion and said second portion is separably bonded to the outer surface of said backsheet (3) in vicinity of associated one of said transversely opposite side edges (1a, 1b) by said anchoring zone. The diaper according to Claim 4, wherein said second portion (12b) is folded back so that said second portion is unfolded outward transversely of said diaper and held in folded back state by said anchoring zone defined at the predetermined regions on the inner surface of said second portion as well as on the outer surface of said second portion. The diaper according to Claim 1, wherein said first portion (12a) has the intermediate region (12a 1 ) thereof extending to describe a curve which is convex outward transversely of the diaper. The diaper according to Claim 1, wherein said fastening tape strips (12) are made of a flexible but non-stretchable plastic sheet. The diaper according to Claim 1, wherein said anchoring zone (12b 1 ) is coated with pressure-sensitive adhesive (18).

Inventors: SHIMADA TAKAAKI, SUZUKI SEIJI, SHIMADA, TAKAAKI, SUZUKI, SEIJI, Shimada, Takaaki, Research &amp; Development Division, Suzuki, Seiji, Research &amp; Development Division
Applicants: UNI CHARM CORP, UNI-CHARM CORPORATION
Application year: 2001
Main classification: A61F13
IPC codes: A61F5, A61F13