NZ207296A - Disposable diapers:reticulated elastic panel extends across and along crotch region - Google Patents

Description

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Complete Specification Filed: Class: Publication Date: P.O. Journal, No: ''2.0 FEB 1987' » • «/ • 111 t i ,i i < i p.

Patents Form No. 5 Number PATENTS ACT 1953 Dated COMPLETE SPECIFICATION ELASTICIZED DISPOSABLE DIAPERS kWe JOHNSON & JOHNSON, a corporation organised under the laws of the State of New Jersey, United States of America of One Johnson & Johnson Plaza, New Brunswick, New Jersey 08933, United States of America do hereby declare the invention for which ?/we pray that a Patent may be granted to MH/us, and the method by which it is to be performed, to be particularly described in and by the following, statement: r; The present invention relates to elasticated disposable diapers.

Elasticated disposable diapers conventionally comprise a fluid pervious facing panel, usually of 5 non-woven material, an absorbent batt below the facing sheet and a fluid impervious backing sheet, the components being secured together by adhesive and elastication being provided by elongated elastic members secured by adhesive along the marginal portions in the 10 crotch region of the diaper. During manufacture, the elastic members are held in a tensioned state until the adhesive has set and thea upon relaxation of the elastic members a gathering effect occurs along the edges of the crotch region of the diaper. Extension of the elastic 15 members occurs during application of the diaper to an infant whereby a sealing effect occurs around the legs of the infant.

Longstanding requirements for disposable diapers are that they be comfortable in use. provide a good fit and 20 conform to the shape of an infant, are effective in use * 'A even when wet or soiled, and are economic to manufacture. It has proven difficult to reconcile all these requirements and considerable effort has been devoted to developing various different diaper types. 25 A published example of a development applicable to elasticated disposable diapers is that disclosed in New Zealand patent specification 194293. 1888S - 2 -i JBD 19 2072^6 ? i; However, it is still considered that new and useful alternatives to previous proposals can be advantageous in the diaper field, and the present invention is concerned with improvements and developments to elasticated disposable diapers.

According to a first aspect of the present invention, there is provided a disposable diaper comprising a fluid impervious backing sheet, a fluid pervious facing sheet, an absorbent batt secured between the facing sheet and backing sheet and elastic means for contracting the crotch region of the diaper and provided by a reticulated elastic panel extending across and along the crotch region of the diaper and secured in an extended condition at least along marginal portions of the crotch region of the diaper for imparting contraction forces at least to the crotch region of the diaper.

The term "reticulated" refers to the provision of openings or apertures which are distributed to produce a generally net-like construction.

Preferably, the reticulated elastic panel comprises a net-like sheet of highly elastic material, for example of the type disclosed in detail in New Zealand Specification No. 194293. Such an elastic panel is highly fluid pervious.

The present invention extends to the case in which the elastic panel is tensioned during manufacture only in the transverse direction or only in" the 'longitudinal - 3 y.PfVTEMT OFFICE lRn 19 1 4 i\'GV 1986 £% '**S* & / /7 ,/ % O w direction of the diaper, although preferably extension of the elastic panel in both the transverse and longitudinal directions is utilised whereby the elastic panel can provide a comfortable and effective means for 5 establishing a fluid leak resistant seal along the legs of an infant in place of a conventional elastic member, as well as providing for contraction of the diaper in the crotch region to provide a good fit with a sump-like effect for receiving and containing waste. 10 Preferably, during manufacture a transverse stretch of the elastic panel by about 80% is provided and preferably a longitudinal elongation by about 50% is also provided.

In a preferred embodiment of the invention, the 15 elastic panel is confined to the crotch region of the diaper and is secured in the diaper by lines of adhesive such as hot melt adhesive which preferably secure the elastic panel to the fluid pervious facing sheet of the diaper.

The present invention is especially applicable to a "contoured" diaper in which the entire diaper has a narrower or central crotch region, such diapers also being known as "hour-glass11 shaped diapers. For this application it is preferred to mount the elastic panel in 25 association with elongated continuous relatively inelastic strips, for example of non-woven fabric material typically of synthetic fibres secured by a 1888S JBD 19 '• 'v binder. The elongated strips are secured to edge portions of the elastic sheet by adhesive to facilitate manufacture of the diaper. Preferably, the diaper manufacturing process includes cutting away side "crotch" 5 portions of the sheet material used for the facing and the backing together with the portions of said strips in the crotch region and the immediately adjacent edge of the elastic panel to leave a narrow crotch. The remaining portion of the elastic panel member is retained 10 in the crotch region by cured adhesive preferably applied as lines of adhesive.

It will be appreciated that due to the reticulated nature or net-like effect of the elastic panel, adhesive such as hot-melt adhesive will penetrate the elastic 15 panel whereby a single application of such adhesive will secure together the sandwich comprising the facing sheet, elastic panel and backing sheet, at least along the edges of the crotch region of the diaper. This produces a relatively smooth, broad elastic characteristic which can 20 spread the elastic load over a considerable area of skin. This provides a high degree of comfort as well as an effective seal against fluid leakage.

Furthermore, in a preferred embodiment of the invention, lines of adhesive are used to secure the 25 elastic panel along the crotch region to the facing sheet and especially when the preferred embodiment utilises both transverse and longitudinal stretch of the elastic 1888S JBD 19 -v . . ' . - V : -- -Jim--. . : : ' ' ' - ' ~ ' m I 2072 panel, the crotch region of the diaper, at least in the facing sheet, is contracted to be bunched and have channels. Furthermore, the elastic panel can induce a sump-like effect in the absorbent batt in the crotch 5 region.

Thus, a most preferred embodiment of the invention consists in a- disposable diaper comprising a fluid pervious non-woven facing sheet, a reticulated elastic panel for applying contraction forces to at least the 10 crotch portion of the diaper and in both transverse and ^ longitudinal directions, the elastic panel being secured by adhesive to the facing sheet in a central region of the crotch portion of the diaper, an absorbent batt and a fluid impervious backing sheet covering the batt and 15 secured thereto by adhesive, the marginal portions of the -facing sheet and backing sheet being secured together by adhesive with the elastic panel being secured by adhesive between the facing sheet and backing sheet in the marginal portions of the crotch region of the diaper, the 20 arrangement being such that in the crotch region a bunching effect is applied to the facing sheet and a sump-like shape is imposed on the absorbent batt.

At least with this most preferred embodiment, a disposable diaper can have an effective combination of 25 properties in that there is provided (a) a high degree of comfort and conformity to the shape of an infant. 1888S JBD 19 207 (b) a high degree of leakage resistance around the legs of the infant. (c) a good capacity for retention of waste in the crotch region of the diaper and (d) the potential for economic manufacture.

A major problem with disposable diaper design is that a good fit can be achieved at the expense of.omitting a high degree of absorption and ability to retain waste in the crotch region, yet the present invention (at least in a preferred embodiment) can provide an advantageous blend of properties especially due to effective application of the concept of using a reticulated elastic panel secured in the crotch region to impart at least a substantially transversely directed contraction force.

According to a second aspect of the invention, there is provided a method of manufacturing a disposable diaper comprising: (a) securing a stretched reticulated elastic panel to a zone on a fluid pervious facing sheet for a diaper, the zone being adapted to correspond with the crotch portion of the diaper when completed, and (b) locating an absorbent batt and a fluid impervious backing sheet over the extended elastic panel and securing the components together by adhesive such that after curing of the adhesive relaxation of the elastic panel causes contraction in the crotch region of the diaper.

JBD 19 -5* V 7 V I -) . -' 'v -,.. r'' ■/— -/■ 2 072 9& Preferably, the method includes supplying elongated substantially non-elastic parallel strips of material, and adhesively forming a sandwich structure comprising the fluid pervious facing sheet, the panel of elastic 5 material in a stretched condition and the non-elastic strips extending along edge portions of the elastic panel, this sandwich structure being secured by adhesive to the absorbent batt and backing sheet with the non-elastic strips extending along lines which extend 10 outside and adjacent to portions which will be the edges of the crotch portion of the diaper when completed, and in the crotch region cutting away side portions of the backing sheet and facing sheet together with said strips and attached edge portions of the stretched elastic panel, 15 The invention will be further exemplified by way of example only with reference to the accompanying drawings of which: Figure 1 is a schematic plan view illustrating the overall manufacturing process for a diaper embodying the 20 invention; Figure 2 is a schematic side elevation of the initial stages of the process illustrated in Figure 1; Figure 3A is a more detailed plan view of the process of Figures 1 and 2; Figure 3B is a side view corresponding to Figure 3A; Figure 4 is a schematic sectional perspective view through a completed diaper prior to its packaging after 1888S _ 8 - JBD 19 / ' 7- r>> the manufacturing process; Figure 5 is a plan view of the finished diaper when in a stretched condition at the end of the manufacturing process but with the facing sheet omitted to show the 5 component parts; and Figure 6 is an enlarged perspective view of reticulated elastic material suitable for use as the elastic panel in the diaper.

Referring first to Figure 1. the manufacturing 10 process commences at the right hand side. Beticulated (^) elastic netting 10 is drawn from a roll and transverse stretching is applied at a stretching device 11 to increase the width of the netting by about 80% and then longitudinal stretch is applied at an elongation unit 12 15 to increase the length of the netting by about 45%. the netting then being severed to form discrete stretched elasticated panels 13. The drive system for advancing the elastic netting is intermittently operated and the rest of the drive system operates continuously to form a 20 stream of completed diapers.

^ The stretched panels 13 are placed on top of non-woven fabric 14 supplied from a roll and to which lines of hot-melt adhesive have been applied in the zone to be occupied by each panel 13. The fabric 14 is for 25 the diaper facing sheet and has continuous lines of adhesive applied along lines adjacent the regions of the edges of the elastic panel, substantially non-elastic 1888S JBD 19 holding strips 15 being applied on top of these continuous lines of adhesive whereby the edge portions of each elastic panel are sandwiched between the facing sheet 14 and the strips 15. It will be noted that the 5 diaper is manufactured "upside down".

After permitting the hot-melt adhesive to be cooled ^ and thus cured, the continuous facing sheet 14 with its associated elastic panels 13 and strips 15 is advanced to a station at which contoured absorbent batts 16 are applied as shown in the drawing with the crotch region of > ... the batt overlying the elastic panel 13. A polyethylene fluid-impervious backing sheet 17 (having applied thereto a multiplicity of fine lines of hot melt adhesive 18) is also introduced at this station and overlies the batt 15 thereby securing the backing sheet 17 in the marginal portions thereof to the facing sheet 14 and in the other regions to the absorbent batt 16.

At a subsequent station, adhesive tape tabs 19 are applied to the portion which will be the rear waist band 20 portion of the diaper, and subsequently at a cutting station central side portions 20 of the facing sheet and backing sheet are removed to provide the final contoured shape: this removal step also removes the central region 15A of the strips 15 and adjacent edge portions 13A of 25 the elastic panel 13.

Finally, individual diapers are produced by transverse cutting thereby leaving portions of the strips 1888S JBD 19 within the diaper structure and the elastic panel arranged to impart contraction both transversely and longitudinally to gather the crotch region of the diaper.

Figure 2 schematically illustrates the configuration for feeding the component parts into the process. Fabric from a roll 21 provides the non-woven facing sheet 14 and passes over suitable guide rollers (not shown) to an adhesive application station 22 at which hot-raelt adhesive lines are applied. Three spaced parallel adhesive lines are provided in the centre region for securing the elastic netting and"a multiplicity of fine lines are provided for each elongated zone at which the strips 15 are to be applied. Elastic netting is supplied from a roll 22A over suitable guide arrangements (not shown in Figure 2 but shown in Figures 3A and 3B) to impart stretch and to apply the netting so as to be secured by the hot-melt adhesive to the non-woven facing 14. The non-elastic strips 15 similarly are supplied from respective reels 23.

At a laminating station 24, the composite (comprising the facing 14, elastic netting formed into panels 13 and continuous elongated strips 15) receives discrete contoured absorbent panels 16 which overlie the elastic panels 13 and a polyethylene backing sheet is supplied from a reel 25. The backing sheet carries hot-melt adhesive which has been applied in lines at a station 18A and when cured secures together the diaper.

JBD 19 ' • / , ^ -•w' ) It has been found that the adhesive tends to migrate into the apertures in the elastic netting and in effect to laminate together the sheet material on the opposite sides of the netting, namely the non-woven fabric strips 5 15 and the facing sheet 14. It should also be noted that further lines of hot-raelt adhesive are provided parallel to and spaced inwardly from the strips 15 so that in a similar way the facing sheet 14 is laminated to the backing sheet 17 as described further below. This can 10 result in the highly advantageous feature of relatively low amounts of adhesive providing a most effective gathering in the region of the elastic netting side portions in the final product since the elastic netting is effectively held in position by a very large number of 15 glue "tacks".

Referring now to Figures 3A and 3B. schematic details of the apparatus for the method described above with reference to Figures 1 and 2 are given.

Stretching of the elastic netting 10 is effected 20 first by a transverse stretching unit 11 comprising a pair of diverging interlocking belts which cooperate with a pair of primary take-off rollers 30 at the downstream end which in turn cooperate with a pair of primary stretch rollers 31 which operate at a greater speed to ) 25 stretch longitudinally the elastic netting 10.

Immediately downstream of the rollers 31 is a hot wire cutter 32 disposed for securing the netting into the 1888S JBD 19 panels 13.

Immediately downstream of the hot wire cutter 32 is the point at which the continuous elongated strips 15 and continuous non-woven facing 14 with applied hot melt 5 adhesive lines are supplied. The hot melt adhesive is forced into intimate contact with the elastic netting and strips 15 by virtue of pairs of laminating belts 33 disposed adjacent the respective sides of the machine and which run over primary and secondary laminating rollers 10 34 and 35. Downstream of the secondary laminating rollers 35 are a pair of chiller rollers 35A typically chilled to about 5°C for ensuring effective and rapid curing of the hot-melt adhesive before the next stage.

The composite structure of the facing sheet 14. 15 elastic netting panel 13 and strips 15 is maintained under tension and transported by a pair of interengaglng tensioning belts 36 at the respective sides of the machine to supply the composite structure to the laminating station 24 Immediately upstream of the pair of 20 laminaitlng rollers provided at the laminating station. discrete absorbent batts 16 and polythene backing sheet 17 is introduced as described with reference to Figures 1 and 2.

After the cutting station (not shown in Figures 3A 25 and 3B.) the diaper as a discrete unit is free and. as shown in Figure 4. contraction of the elastic netting panel 13 tends to cause a longitudinal gathering, and 1888S JBD 19 m...., - ■ : ' \ V /'1 ,- . . . ""■ " .v-A,V ... ^ - : v-.- ~\ J 20729S under the influence of the transverse contraction the formation of channels and ruffles 40 and 41 in the facing sheet 14 occurs. Fine gathering is also provided at 42 along the edge portions of the crotch region of the 5 diaper for providing a seal against the infant's legs. It will be noted that lines of adhesive 43 secure the facing sheet in the central portion to the elastic netting panel 13. and a multiplicity of fine lines of adhesive 44 secure together the facing sheet, side 10 portions of the elastic netting 13 and backing sheet 17 in the marginal portions of the crotch region of the diaper. It will also be noted that the absorbent batt 16 has a sump-like shape (exaggerated for clarity in the drawing) and has a thickness which is contoured in the 15 transverse direction. ' Whereas Figure 4 is a schematic illustration and sketch illustrating the effect that can be produced by the invention. Figure 5 is a more detailed view illustrating a contoured diaper in a stretched condition 20 at the end of the production line.

Figure 5 shows the diaper arranged the correct way up with the facing sheet 14 removed to show the remaining parts. The polyethylene backing sheet 17 has a multiplicity of parallel lines of adhesive 17A which hold 25 the absorbent panel 16 in position and in the marginal portions of the diaper hold the facing sheet 14 securely. The remnants of the holding strips 15 are 1888S JBD 19 y ,'y 296 eecured in the end portions of the diaper by virtue of two of these lines of adhesive, although a multiplicity of four fine lines of adhesive 44 are used for securing together the structure in the final marginal portion at 5 each side of the crotch region of the diaper. In just the crotch region of the diaper, major lines of adhesive 43 are applied for securing the facing sheet to the elastic netting panel 13.

Referring now to Figure 6. a suitable form of sheet 10 like.material is shown for the reticulated elastic panels described above. The material shown in Figure 6 comprises a branched or net-like construction 61 having openings or apertures 60 therein. The openings may be of any suitable shape and configuration although the 15 embodiment shown in the drawing has square uniformly arranged openings. Alternatively the openings may be. for example, round, oval or other shapes. The array of openings need not be symmetrical or regular and in general the reticulated elastic material may simply be 20 provided by a multiplicity of inter-connected elastic elements between which apertures are defined.

W Depending on the modulus of elasticity of the material used and the thickness and width of the elastic member, the number of openings may vary from two to one 25 hundred openings per linear inch in both the longitudinal and transverse directions of the member. Furthermore the elastic elements may be of different widths in the 1888S - 15 - JBD 19 i •':-I longitudinal or transverse directions and the spacing between the elastic elements may vary from the transverse to the longitudinal direction. % 7 O 1888S JBD 19 07

Claims (11)

WHAT WE CLAIM IS:

1. A disposable diaper comprising a fluid impervious backing sheet, a fluid pervious facing sheet, an absorbent batt secured between the facing sheet and 5 backing sheet and elastic means for contracting the crotch region of the diaper and provided by a reticulated elastic panel extending across and along the crotch region of the diaper and secured in an extended condition at least along marginal portions of the crotch region of 10 the diaper for imparting contraction forces at least to (^) the crotch region of the diaper.

2. A disposable diaper as claimed in Claim 1, and wherein the elastic panel is extended for imparting both transverse and longitudinal contraction forces. 15

3. A disposable diaper as claimed in Claim 2. and wherein when the diaper is extended to a flat condition the reticulated elastic panel is stretched by about 80% in the transverse direction and by about 50% in the longitudinal direction of the diaper. 20

4. A disposable diaper as claimed in any one of the preceding claims and wherein the reticulated elastic panel extends substantially throughout the crotch region of the diaper and is secured by lines of adhesive to the fluid pervious facing sheet of the diaper. 25

5. A disposable diaper as claimed in any one of the preceding claims wherein the diaper is contoured to have a relatively narrow crotch region and the diaper is 1888S - 17 - JBD 19 *';207296;manufactured by the use of relatively inelastic strips adhesively securing the stretched reticulated elastic panel to the facing sheet of the diaper and before completion of the diaper, portions of the facing sheet and the strips are cut away at the side of the diaper to leave the relatively narrow crotch region of the diaper with adhesive securing the marginal portions in the crotch region of the diaper to attach the elastic panel to both the facing sheet and backing sheet.;

6. A diaper as claimed in any one of the preceding claims and wherein lines of hot-melt adhesive secure the elastic panel in the crotch region of the diaper to the facing sheet.;

7. A disposable diaper comprising a fluid pervious non-woven facing sheet, a reticulated elastic panel extending across and along the crotch region of the diaper and secured in an extended condition for applying contraction forces to at least the crotch portion of the diaper and in both transverse and longitudinal directions, the elastic panel being secured by adhesive to the facing sheet in a central region of the crotch portion of the diaper, an absorbent batt and a fluid impervious backing sheet covering the batt and secured thereto by adhesive, the marginal portions of the facing sheet and backing sheet being secured together by adhesive with the elastic panel being secured by adhesive between the facing sheet and backing sheet in the marginal portions of the crotch region*of the diaper, the arrangement being such that in the crotch region a N.2. PATENT OFFICE - 18 - | 1 4 HOV1986 RECEIVED JBD 19 r\ / 7;;/ , 207296 bunching effect is applied to the facing sheet and a sump-like shape is imposed on the absorbent batt.

8. A method of manufacturing a disposable diaper comprising: 5 (a) securing a stretched reticulated elastic panel to extend across and along a zone on a fluid pervious facing sheet for a diaper, the zone being adapted to correspond with the crotch portion of the diaper when completed, and (b) locating an absorbent batt and a fluid impervious 10 backing sheet over th.e extended elastic panel and securing the components together by adhesive such that after curing of the adhesive relaxation of the elastic panel causes contraction in the crotch region of the diaper. - 15

9. A method as claimed in Claim 8, and wherein the method includes supplying elongated substantially non-elastic parallel strips of material, and adhesively forming a sandwich structure comprising the fluid pervious facing sheet, the panel of elastic material in a 20 stretched condition and the non-elastic strips extending along edge portions of the elastic panel, this sandwich structure being secured by adhesive to the absorbent batt and backing sheet with the non-elastic strips extending along lines which extend outside and adjacent to portions 25 which will be the edges of the crotch portion of the diaper when completed, and in the crotch region cutting away side portions of the backing sheet and e 1888S - 19 -j i i i'.'oo RECHiVSP ■ JBD 19 ■. ~ .... ■■ ■ .... ■■■ v.,;... V;v I ■■ . , ■ ,'v V, - ,'7; 1 , "V ^ o / facing sheet together with said strips and attached edge portions of the stretched elastic panel.

10. A disposable diaper substantially as herein described with reference to the accompanying drawings. 5

11. A method of manufacturing a disposable diaper substantially as herein described with reference to the accompanying drawings. 10 WEST-WALKER, McCABE per: 15 ATTORNEYS- FOR THE APPLICANT 20 3 25 1888S - 20 - JBD 19