Abstract:
A method of producing an elasticized member having two different degrees of stretch, to be used in an absorbent product. The method involves stretching an elastic member by a first amount and securing part of it in the stretched condition to an inelastic web, while a second portion of the elastic member is stretched by a second amount and secured in the stretched position to the first web or to a second web. Differentially stretched products produced by the method can be used to provide advantages in terms of material savings and elasticity effects in absorbent products.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. §119 to U.S. Provisional Application No. 60/368,979, filed on Apr. 2, 2002. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a method of producing a differentially stretched member, such as a differentially stretched elongated strip, for use in an absorbent product (such as a diaper or the like for absorbing human exudate). In particular, the invention relates to a method of producing a differentially stretched member for use in the waist area of such an absorbent product. 
     BACKGROUND OF THE INVENTION 
     There is often a desire to provide a part of an absorbent product with differing degrees of elastic extension. For example, in the waist region a strip of elastic material is often placed between the top and back sheet having been given a pretension of some 30 to 80%, in order to provide an elasticized waist portion. Similarly, elastic side flaps, with a high degree of elasticity (i.e. able to be extended by a large distance elastically) and including an attachment means at the outer end of each flap, may be provided on one waist portion of an absorbent product for releasable attachment to a second waist portion. 
     The presence of an elasticized waist and elasticized side flaps requires differing elastic material portions to be handled and applied in a series of manufacturing operations. As a solution to this inconvenience, a single elastic strip member of high elasticity may instead be used to span across both the waist and end flaps, whereby the entire waist band and the end flaps are both imparted with a high degree of elasticity. However, since the waistband is not normally stretched to the available extent of this high degree of elasticity, the waist band material where the elastic strip member is attached will generally comprise very coarse gathers. The presence of these coarse gathers may affect either the comfort and/or the containment characteristics of the product. Additionally, when a highly stretched elastic material is attached in the waistband, a greater amount of material is required in the top sheet and/or back sheet in order to produce any given size of waist area, since the coarse gathers require a significant amount of top sheet and/or back sheet material. 
     The invention seeks to overcome the above problems, whereby individual areas of an absorbent product can be provided with differing degrees of elasticity such that differing areas can be stretched elastically by differing amounts, without resorting to the use of different elastic members in the different areas of the product. 
     WO-A-01/87213 discloses elasticated areas such as leg or waist areas, added to absorbent products. The elasticated areas are formed as laminates, in which a nonwoven elastic material is stretched and then fixed between two outer layers of inelastic material. The resulting laminate is provided with regions of differing elastic tension or in other words differing elastic modulus. This can be achieved for example by using elastic filaments which are separated by a different distance in two different parts of the laminate, or by using a different elastomeric polymeric compounds or mix of elastomers for the filaments in one part of the web compared to another part, or even by choosing different diameter filaments in different parts of the web. The filaments for the different areas of the web are passed over a common series of rollers in order to be stretched by a certain amount before being attached. In this way, all filaments are stretched the same distance. The resulting differently formed areas of the laminate may each be stretched, by different maximum forces up to the maximum extension of the non-elastic material, which thereby provides different characteristics in the same laminate. 
     Although the resulting laminate in WO-A-01/87213 includes areas of different elastic modulus, this does not concern the problem of providing areas of different elastic strain in a single member. 
     SUMMARY OF THE INVENTION 
     These and other objects are achieved by providing a method of producing a member which has been differentially stretched, and a product produced thereby. 
     In accordance with embodiments of the invention, an elastic member is used in combination with at least one relatively inelastic member. 
     An elastic member, such as a continuous or discontinuous sheet, web, layer, or net for example, is considered to be elastic in accordance with the invention if it can be elastically extended by more than 50% without substantial permanent strain, whereby substantial permanent strain is understood as being of the order of more than about 10 to 30% of the initial length at the first stretching. In most cases, elastic materials used in accordance with embodiments of this invention will have an elastic extensibilty of more than 100%, more preferably more than 200% or even more preferably more than 300%, and still more preferably more than 400%. Elastic members suitable for the invention may include for example, non-exclusively, elastomers made from block copolymers such as polyurethanes, copolyetheresters, polyamide polyether block copolymers, EVAs (ethyl-vinyl-acetates), elastomeric styrene-butadiene copolymers, tetrablock copolymers, including styrene-poly(ethylene-propylene) elastomeric block copolymers, polyamides, or natural and synthetic rubber materials, etc. One suitable elastomer is Extraflex™ CEX 802WR having a surface weight of 54 g/m 2 , available from Tredegar film products. 
     Relatively inelastic members may comprise a continuous or discontinuous sheet, web, layer or fabric for example, which member can be stretched elastically by only small amounts, normally of the order of between 1 to 15%, but typically less than 10%. 
     A differentially stretched member is produced by applying different extension forces to different parts of an elastic member, preferably a uniform elastic member such as a film or net of homogenous material, or by applying the same extension forces to non-homogenous and/or non-uniform parts of an elastic member, before attachment of said elastic member to at least one relatively inelastic member. The resulting differentially stretched member may be a laminate or other layered structure, for example a substantially non-elastic sheet of an absorbent product attached to an elastic member. The differentially stretched member structure will thus comprise at least two portions, in series, the portions having different elastic properties in terms of elastic strain, such that when the structure is subjected to opposed lateral extension forces, the structure will be able to be extended elastically by a different amount in one portion as compared to the other portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be explained in more detail with reference to certain non-limiting embodiments thereof and with the aid of the accompanying drawings, in which: 
         FIG. 1  shows a plan view illustrating the steps of a first embodiment of the invention, 
         FIG. 2  shows a plan view illustrating the steps of a of a second embodiment of the invention, 
         FIG. 3  shows a plan view and cross-sectional views illustrating the steps of a third embodiment of the invention, 
         FIGS. 4   a  and  4   b  respectively show a plan view and cross-sectional view of a differentially stretched member in a relaxed condition, 
         FIGS. 5   a – 5   c  show cross-sectional views through a differentially stretched member in the form of a net undergoing production, 
         FIG. 6  shows a plan view of a differentially stretched band attached to an absorbent product in the waist region thereof, 
         FIG. 7  shows a cross-sectional view on to line VII—VII in  FIG. 6 , 
         FIG. 8  shows a cross-sectional view similar to  FIG. 7  of an alternative embodiment, 
         FIGS. 9   a – 9   d  show a plan view and sectional views of a further embodiment of the invention whereby the top sheet and back sheet are used as first and second relatively inelastic webs, 
         FIG. 10  shows a schematic plan view of a still further embodiment of the invention, 
         FIG. 11  shows a pair of strips, each made in accordance with the second embodiment, and each attached to respective side edge portions of an absorbent product, 
         FIGS. 12   a  and  12   b  show cross-sectional views of a still further embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     In  FIG. 1 , an elastic member  1  in the form of an elongate rectangular strip, preferably of a uniform elastic material or possibly a net of uniform filaments, is placed above a first web  7 . The first web is in the form of a continuous sheet of a relatively inelastic material. The member  1  thus has two major surfaces constituted by the upwardly facing surface in the Figure and the opposite lower surface. In step (a), the member  1  is laid flat on the first web  7  with one of its major surfaces overlying and preferably adjacent to the first web  7 . 
     In step (b), the respective ends  8 ,  9  of the member  1  are each held by a suitable gripping means such as two sets of gripping jaws or gripping belts (not shown) of a manufacturing machine (not shown) and said gripping means are each moved outwardly in opposite directions respectively, as indicated by the opposed arrows A. In this way, the entire elastic member  1  is stretched into a first stretched condition. A suitable amount for this first stretched condition is an extension of e.g. between 30% and 80%, for example about 50%. 
     A first portion  2  of the elastic member is shown in  FIG. 1  as extending between the upper and lower edges of the strip and between dashed lines  3  and  4 . The first portion  2  is also positioned generally centrally with respect to the elastic member and also with respect to the first web  7 , although off-centre arrangements (not shown) may be used. 
     The first portion  2  is maintained in the first stretched condition. This may be performed either by simply maintaining the gripping means at the initial extension or by the application of alternative means such as holding fingers (not shown) at, or outside of, lines  3  and  4 , which will hold the first portion  2  in said first stretched condition. 
     In this maintained first stretched condition, the first portion  2  may now be fixedly secured to the underlying first web  7 . Fixed securement may be carried out in any suitable manner such as by e.g. ultrasonic welding, heat welding, or by the use of adhesive (e.g. hot melt adhesive) applied preferably uniformly over the first portion  2  of member  1  between the first web  7  and the member  1 . 
     With the first portion  2  maintained in said first stretched condition, each of the portions on either side of the first portion constitutes a second portion  5 ,  6  of the elastic member  1 . In the next step, step (c), each of the gripping means mentioned above then moves further in the direction of the opposed arrows A so as to extend each of said second portions  5  and  6  by a second amount which is greater than said first amount. The second amount may for example be a stretch of each of the second portions of the elastic member (compared to an unstretched condition of said second portions) by an amount of up to 100% when the first portion has been stretched by up to 30%, or by an amount up to 200% when the first portion has been stretched by up to 60%, or up to 300% when the first portion has been stretched by up to 100%, or by up to 500% when the first portion has been stretched by up to 150%. As shown in  FIG. 1 , the ends  8  and  9  have been stretched suitably to coincide substantially with the outer edges  10 ,  11  of the first web  7 . 
     In the condition shown, each of the two second portions  5 ,  6  is securely fixed to the first web  7  by any suitable method, such as those described above with reference to securely fixing the first portion  2  to the web  7 . Preferably the same method is used to fixedly secure the first portion  2  and the second portions  5 ,  6  to the first web  7 . 
     Although in the aforegoing embodiment the secure fixing of the first portion  2  to the first web  7  precedes the fixing of the second portions  5 ,  6  it is also possible to keep the first portion in said first stretched condition while stretching said second portions to said second stretched condition and only then fixedly attach the first web  7  to the first portion  2  and to the second portions  5 ,  6 . Thus the first portion  2 , although preferably attached to the first web  7  before the second portions  5 ,  6  can also be attached at the same time as the second portions are attached to the first web  7 , or the first portion  2  could be attached after the second portions  5 ,  6  have been attached. 
       FIG. 1  shows the web  7  as a continuous web having a width (left to right in the Figure) equal to the width of the finally stretched elastic member  1  but with a greater height (top to bottom in the Figure). In such an embodiment, the differentially stretched strip formed at the end of step (c) may be cut from the continuous first web  7  at a cutting station (not shown). It will also be clear that, particularly for mass production, the elastic members  1  may be applied consecutively, or in groups, to the underlying web  7 , with little or no gaps between consecutive elastic members  1 . 
     In a still further embodiment, the elastic member may instead be formed as a continuous elastic web (i.e. like web  7 ) or in the form of an elastic web having a net structure, and the various operations shown in steps (a), (b) and (c) would be carried out sequentially during forward movement of both elastic and non-elastic webs such that a differentially stretched web comprising the combined web  7  and the elastic member web is formed. To use the combined web as a differentially stretched member in absorbent products, a cutting stage (not shown) would then be required before adding to the absorbent product. 
     Embodiments are also envisaged where the first web  7  is however shorter and generally corresponds to the height dimension (top to bottom as shown in the Figure) of elastic member  7  when in its stretched condition such that little or no trimming is required. 
     Although only a first web  7  is shown attached to one major surface of the elastic member  1 , it should be understood that a second web (not shown), for example a second relatively inelastic web, preferably of the same material as the first web, may be applied to the other major surface of the elastic member  1 . In such an embodiment, the operations of fixed securement of the first and second portions in the respective first and second stretched conditions should be carried out such that both the first and second webs are fixedly attached to the elastic member  1  at each securement operation. In this way, the elastic member becomes affixed or laminated between the first and the second webs. 
     The first and/or second web is preferably made of an inelastic nonwoven material. A typical nonwoven web may be made in the form of a spunbonded PP (polypropylene) fabric or an S-M-S (spunbond-meltblown-spunbond) fabric for example. Further examples are other types of spunbonded nonwovens or other nonwoven materials such as carded material, or material manufactured in another way. The nonwoven material can for example be made of synthetic fibres such as polyolefins, for example polypropylene or polyethylene. Other fibres such as for example different types of polyesters or nylon are also possible. It is further possible to use bi-component fibres and/or fibre mixtures of two or more different fibre types. One specific example of a nonwoven for use with the invention is a spunbonded nonwoven of polypropylene fibres having a basis weight of 12–30 g/m 2  and a fibre thickness of 0.5–5 dtex. Other nonwoven fabrics or webs may also be used. 
     Since the differentially stretched strip members are to be used in absorbent products, the relatively inelastic material should clearly be chosen to be soft, at least on the surface intended to contact the wearer&#39;s skin, and preferably on both surfaces. 
     In a second embodiment shown in  FIG. 2 , parts similar to those in the first embodiment have the same reference numerals raised by  100 . 
     The differentially stretched strip of the second embodiment is produced in a manner similar to the strip of the first embodiment, but the final product only has one second portion  105 . In step (a), the elastic member  101  is thus placed above and adjacent the first web  107 . 
     In step (b), the elastic member  101  can be held stationary at its left edge  109  while the opposite edge  108  is gripped by suitable means (not shown) such as those described in the first embodiment. The gripping means are then moved in the direction of arrow A so as to stretch the entire elastic member by a first amount, said amount preferably being about 30 to 80% of the initial unstretched length of the elastic member  101 . A first portion  102  is designated, said first portion extending from edge  109  to dashed line  104  and bounded by the upper and lower edges of the elastic member  101 . 
     The first portion is then maintained in said first stretched condition and then attached fixedly to the underling web, whereby edge  109  of the elastic member is aligned with the edge  111  of the first web  107 . 
     In step (c), the single second portion  105 , positioned to the right of the first portion  102 , is stretched in the direction of arrow A by a second amount which is different to and preferably greater than the first amount, the second amount may for example be a stretch of the second portion of the elastic member (compared to an unstretched condition of same) of greater than 100%, for example 200%. In this stretched condition, the edge  108  of the second portion  102  is preferably aligned with the edge  110  of the first web  107 . 
     The second portion  102  is then fixedly secured, by any suitable means such as welding, adhesive or the like, to the first web  107 . 
     The materials used in the first embodiment are equally applicable to use in the second embodiment and further embodiments, as are the attachment methods employed and the order of the steps in which fixed securement takes place. 
     A suitable area of use for the differentially stretched strip of the second embodiment is as a waist side flap of an absorbent diaper, whereby the first portion  102  of said differentially stretched strip is attached to one edge of an absorbent product and the second portion  105  extends from one edge of said absorbent product.  FIG. 11  shows an example of such an attachment. 
     In a third embodiment of the invention, shown in  FIG. 3 , a method of producing a differentially stretched belt having a first web and a second web is shown. Cross-sectional views of the elements in each stage are shown to the right in  FIG. 3 , whereby the thickness dimensions of the cross-sectional views are oversized for reasons of clarity. In this third embodiment, elements similar to those in the first embodiment have reference numerals raised by  200 . Thus, in step (a), the respective major surfaces of the elastic member  201  are placed over and adjacent a relatively non-elastic first web  207  and underneath and adjacent a second web  212  respectively. 
     In step (b), the elastic member  201  is stretched by a first amount in a similar way to that described with respect to the first embodiment, by the order of about 30% to 80%. The elastic member  201 , and thereby a first portion  202  having left and right imaginary boundaries  203 ,  204  shown in dashed lines, is maintained in said first stretched condition and said first portion  202  is fixedly secured to said first web  207  and to said second web  212 . In the embodiment shown, attachment areas  213 ,  214  are shown positioned between the second web  212  and the first portion  202  and between the first web  207  and the first portion  202 . Said attachment areas may for example be constituted by an adhesive which has been pre-coated on the surface of the elastic member  201  and/or the first and second webs  207 ,  212 , whereby the adhesive may be activated by the use of heat applied through the area bounded by dashed lines  203 ,  204 . Alternatively, the attachment areas  213 ,  214  may be regarded as being a weld, or other fixed attachment, between the elastic member and the first and second webs respectively. 
     In step (c), two second portions  205 ,  206  of the elastic member  201  are each stretched by a second amount, e.g. of the order of 100% or more. In the shown embodiment, the second portions  205 ,  206  are stretched such that their outer edges  208 ,  209  each are generally aligned with the outer edges  210 ,  211  of the first web  207  and the second web  212 . However it will be evident that the elastic member  201  may also be stretched to an amount such that its outer end edges lie outside the end edges  210 ,  211 . 
     The second portions are then secured fixedly to the first and second webs  207 ,  212  respectively while said second portions  205 ,  206  are still in said second stretched condition. A similar method of attachment as used for attachment of the first portion  202  to the first and second webs  207 ,  212  may be used. 
     When the differentially stretched strip is released from the gripping means it assumes a relaxed state and has the shape of a rectangular strip as shown in  FIG. 4   a  in plan view, whereby said elastic element has returned generally back to its initial length, although it is generally slightly longer due to some permanent elongation of the elastic material.  FIG. 4   a  and  FIG. 4   b  are however drawn on a different scale to  FIG. 3  so as to more clearly indicate the gathers.  FIG. 4   b  shows a cross-sectional view on to line IVb—IVb in  FIG. 4   a.  In  FIG. 4   a  and  FIG. 4   b,  it can be seen that the first portion  202  and the second portions  205 ,  206  have each drawn the relatively inelastic first and second webs  207 ,  212  into a gathered condition by different amounts, whereby coarse gathers are present on the two second portions  205 ,  206  and fine gathers are present on the first portion  202 . The coarseness of the gathering may of course also be affected by the actual pattern of binding sites between the elastic and non-elastic webs. 
       FIG. 5  shows a further embodiment of the invention in cross-sectional view, not to scale, whereby the elastic member  301  is in the form of a net of elastic material. The net has longitudinal and laterally extending elastic material strands  315  surrounding apertures  316 . Apertures  316  may be, for example, square or rectangular in shape. The cross-sectional shape of the elastic net members is shown as rectangular, but may be any suitable shape such as square, oval, circular, or any other shape. 
     In step (a) the elastic  301  member is placed between two relatively inelastic first and second webs  307 ,  312  and then stretched in mutually opposite directions denoted by arrows A, as explained with reference to the aforegoing embodiments. 
     As shown in step (b), a first portion  302  of the elastic member  301  located generally at the middle of the first and second webs  307 ,  312  is fixedly secured by means of the first and second webs  307 ,  312 , by means of weld areas  317 , such as ultrasonic weld areas, or adhesive or the like, whereby the first web  307  is connected to the second web  312  directly through the apertures  316  in the net, over preferably all the area of the first portion bounded by imaginary lines  303 ,  304 . 
     In step (c), the net is stretched by a second, greater amount, such that the ends of the net generally extend up to the ends of the first and second web. In this stretched condition, the second portions  305 ,  306  of the elastic member are fixedly secured to respective outer portions of the first and second webs  307 ,  312  for example by welding or adhesive. 
     Although a net is used as the elastic member  301  in  FIG. 5 , the elastic member could equally be a continuous elastic film (not shown) without pre-formed apertures. The two webs  312  and  307  could however still be joined by means of e.g. ultrasound welding through the elastic film, thereby creating apertures in said film where webs  312  and  307  are joined. Alternatively, adhesive may be used for example. 
       FIG. 6  schematically shows an absorbent diaper  318 , typically comprising a top sheet  323  and back sheet  324  surrounding an absorbent core  335  which could comprise cellulose fluff or other absorbent material, optionally mixed with superabsorbent gelling material. The diaper  318  has two opposed ends, each comprising a waist portion  319 ,  320  including the top sheet  323  and the back sheet  324  and optionally a part of the absorbent core. Between each waist portion there are curved leg openings  321 ,  322 . Additional features such as standing gathers and elastics of various types may also be fitted in the longitudinal direction of the diaper. Such additional features are well known in the art. 
     Further, a differentially stretched member  301 ,  307 ,  312  in the form of a rectangular strip (shown as a single element) has been fixed to the upper end waist portion  319 , whereby the first portion  302  together with its attached first and second webs  307 ,  312  can be initially stretched to its elastic limit (i.e. the first amount of stretching) and then fixedly attached in a relatively flat condition to the top sheet  323  and/or to the back sheet  324  which are also in a relatively flat condition. The second portions lie outside the outer edges  325 ,  326  of the waist portion  319  formed by the top and back sheets  323 ,  324 . 
     When allowed to relax, the absorbent product gathers the waist region  319  as the first portion  302  returns to its relaxed length. Each of the outer portions  330 ,  331  (i.e. second portions  305 ,  306  with attached first and second webs  307 ,  312 ) of the differentially stretched member is fitted with an attachment means  327 ,  328  respectively. Said attachment means  327 ,  328  can for example releasably attach to a corresponding member  329  on the outer surface of the opposite waist portion  320  in a stretched condition of said outer portions  330 ,  331 , such that the members  327 ,  328  and  329  respectively together form a releasable attachment means, for example of the mechanical type provided with cooperating hook and loop type fasteners (e.g. Velcro®), or the like. 
     Alternatively, only one of the members  327  or  328  need be present on one outer portion, for example in the form of a strip  327  of hook-type material of a hook and loop type fastener, or other similar mechanical fastener, whereby the two outer portions  330 ,  331  can be passed around a user&#39;s waist and the attachment strip  327  is engaged in the outer surface of outer portion  331  to thereby secure the outer portions  330 ,  331  together in the form of a belt. Attachment means such as hook-type attachment strips  332 ,  333  on the top sheet  323  may then be used to fix the front waist part  320  of the absorbent product to the waist belt formed by the connected portions  330 ,  331 . 
     Although the portion  302  has been shown substantially equal in lateral extent to the extent of the top and back sheets in  FIG. 6  such that the outer portions  330 ,  331  start at the edges  325 ,  326  of the top and back sheets  323 ,  324  in the waist portion  319 , it is to be understood that this is only exemplary and the outer portions  330 ,  331  may start laterally inside the outer edges  325 ,  326 , or they may start laterally outside the outer edges  325 ,  326 . Additionally, the first portion  302  and its attached webs  307 ,  312  do not need to be attached to the top and/or back sheets over the whole area (as indicated by the dotted area in  FIG. 6 ), but instead may be attached over a smaller area (e.g. over only a central portion of the top and/or back sheet in the waist portion  319  lying inside the edges  325 ,  326 ). Thus, for example the first portion need only be attached to the waist region  319  over a distance of between 25% and 75% of the distance between the edges  325 ,  326  for example. As a further example, the first portion may be attached to the waist region all the way along the upper edge (i.e. the outermost edge) of the depicted dotted area of same but not at the lowermost edge in a middle portion, such that in this way an inwardly open pocket can be formed having lines of connection proximate the outer edge and proximate the edges  325 ,  326 . Such a pocket can be used for holding exudate and thus improving leakage resistance. 
       FIG. 7  shows a cross-sectional view along line VII—VII in  FIG. 6 , wherein the differentially stretched member comprising the elastic member  301  combined with first and second webs  307 ,  312 , is shown as a single layer sandwiched between, and fixedly attached to, the top sheet  323  and back sheet  324  of the absorbent product. 
       FIG. 8  shows an alternative embodiment, similar to  FIG. 7 , wherein the differentially stretched strip member comprising layers  301 ,  307 ,  312  is affixed to the outer surface of the back sheet  324 . The attachment may be made over the whole area of contact of the back sheet  324  with the differentially stretched member, or only over part of the area, such as over an area having length  334 . The top sheet  323  and the back sheet  324  are joined directly. In this embodiment, the outer portions  330 ,  331  of the differentially stretched member start inside the edges  325 ,  326  of the top and back sheets  323 ,  324  and the middle portion  334  corresponds to the part of the differentially stretched member containing the first portion  302 . 
       FIG. 9   a  and  FIG. 9   c  show two different stages of production in plan view, while  FIG. 9   b  shows a cross-sectional view on to line IXb—IXb and  FIG. 9   d  shows a cross-sectional view on to line IXd—IXd in  FIG. 9   c.    
     In  FIG. 9   a  top sheet  423  is attached to a back sheet  424  in a similar way to that shown in  FIG. 6 . However, the embodiment of  FIG. 9  and  FIG. 6  differ in that in  FIG. 9  both the top sheet  423  and back sheet  424  are used to sandwich an elastic member  401  therebetween. Thus the differentially stretched member is formed of three parts, the top sheet  423  as a first relatively inelastic web, the back sheet  424  as a second relatively inelastic web and an elastic member  401 . 
     In accordance with the earlier described methods, the elastic member  401  is stretched in opposing directions indicated by arrows A by a first amount and then a first portion  402  is fixed securely to the top sheet  423  and/or back sheet  424  by suitable means as described previously, such as by ultrasonic welding for example. In the shown embodiment, the elastic member  401  is however fixed to both the top sheet  423  and the back sheet  424 . Then, the two outer portions  405 ,  406  of the elastic member are stretched by a second greater amount so that their ends become aligned substantially with the outer ends of the top and back sheets  423 ,  424 . Then the two second portions  405 ,  406  are secured in said extended condition to the top and back sheets  423 ,  424 . 
     When allowed to relax (not shown), the first portion  402  will gather the central waist portion top and back sheets  423 ,  424  until the elastic member has returned substantially to its initial length in the first portion, and the two second portions  405 ,  406  will gather the top and back sheets  423 ,  424  by an additional amount. As a result, the central part of the waist band may then be stretched elastically by a first amount e.g. up to 50% to resume a relatively flat condition and the outer portions may be stretched elastically by a greater amount e.g. up to 150% or more. 
     In the embodiment shown in  FIG. 10 , a differentially stretched member such as that resulting from the final step in the  FIG. 1  embodiment, or the embodiments in  FIGS. 4   a – 4   b,  and  5   a – 5   c  for example, is used to form one waist portion  519  of an absorbent product. The differentially stretched member is fixedly attached, e.g. by welding or adhesive or the like, to the upper end  534  of an absorbent product such as the absorbent product shown in  FIG. 6  but without an upper waist portion formed by the top and back sheets  523 ,  524 . Suitable releasable attachment means  527 ,  528  may be provided on the waist portion  519  to releasably attach to corresponding means  529  on the opposite waist portion  520  so as to be able to releasably attach the waist portions  519 ,  520  together. 
       FIG. 11  shows a top waist portion of an absorbent product formed by a top sheet  123  joined to a back sheet  124  with absorbent core (not shown) therebetween. In the waist region  119  thereof, a pair of differentially stretched members produced by for example the method shown in  FIG. 2  are attached one to each side of the waist region  119 . The attachment is such that the first portion  102  (together with the attached first web and second web) is attached to the top sheet  123  and/or the back sheet  124 , whereby the outer edge  104  of said first portion is preferably aligned with an outer edge of said top sheet  123  and/or said back sheet  124 . In such a way, a first degree of elastication is given to the waist region at the outer edges of the waist portion and a second higher degree of elastication is given to the flap members (i.e. those parts of the differentially stretched member extending outside the first portion  102 ). 
     Further embodiments will be readily understood by the skilled person upon reading the aforegoing and are intended to be encompassed within the scope of the invention as defined by the appended claims. For example, although the differentially stretched member has been described as a rectangular strip, other shapes of strip are also possible, such as oval. 
     Further, although a first portion and at least one second portion have been described, it should be understood that the invention can be applied to an elastic member having further portions, whereby one or more further portions may be located between the first and second portions, and/or outside the second portions, and the elastic member subject to at least one different, preferably larger, amount of stretching for each additional portion. 
     In the aforegoing description, the elastic member has been described as preferably comprising a uniform elastic web. However, the idea behind the invention may also be used with non-uniform elastic webs such as that depicted in  FIGS. 12   a  and  12   b,  a non-uniform cross section elastic member  601  of substantially homogenous elastomeric material having a central first portion  602  and two second portions  605 ,  606  is shown positioned in an unstretched state between two relatively inelastic webs  607 ,  612 . 
     A single set of opposed forces in the direction of arrows A are applied to the elastic member  601  so that the outer ends of the elastic member  601  align approximately with the outer ends of the inelastic webs  607 ,  612 . The outer ends of the elastic member  601  could however instead be extended further than the outer ends of the inelastic webs or not as far out as the outer ends of the inelastic webs. The elastic member  601  is then fixedly attached, by any suitable methods as described with respect to the aforegoing embodiments, to either or both webs  607 ,  612  at its first portion  602  and at both its outer portions  605 ,  606 . In this way, a differentially stretched member can be produced without needing to apply two different extensions. As will be evident, the first portion  602  has been elongated over a shorter distance than the outer portions since it exhibits a greater modulus of elasticity, and thus the resultant strain is less on the central portion (i.e. the central portion is extended less compared to its original length than the outer portions). When the resulting laminate is then allowed to relax, the central part will cause a minimal gathering whereas the outer portions will gather more. When the laminate is stretched again, the central portion can only be stretched by a small distance elastically whereas the outer portions may be extended elastically a greater amount. 
     A further adjustment can be made in the embodiment described with respect to  FIGS. 12   a  and  12   b  as described in the following. After the single force has been applied to stretch the entire elastic member  601  (for example such that the outer ends of the elastic member  601  lie outside the outer ends of the inelastic webs  607 ,  612 ), the first portion  602  can be fixedly attached to the inelastic webs  607 ,  612 . Then the force stretching the elastic member in the direction of opposed arrows A is then reduced somewhat followed by subsequent attachment of the second portions to the webs  607 ,  612 . In this way, a laminate is obtained which can be stretched to a maximum in the outer areas (corresponding to the second portions) before the central area has approached its maximal extension. 
     The different modulus of elasticity of the first portion  602  in  FIGS. 12   a  and  12   b  as compared to portions  605 ,  606  can also be obtained in other ways such as for example by using a different polymer mix in these different portions, or by adding strengtheners or additional fibres or the like in the portion  602  compared to portions  605 ,  606 . 
     The invention may be used as a waist belt or a waist band which is to be attached to a waist portion of a top sheet and/or back sheet of an absorbent product, or which is to form the waist portion of an absorbent product. The invention also relates to products resulting from said method. Further features of the invention will be apparent to the reader of this specification. 
     Although only preferred embodiments are specifically illustrated and described herein, it will be appreciated that many modifications and variations of the present invention are possible in light of the above teachings and within the purview of the appended claims without departing from the spirit and intended scope of the invention.