Latent elastic olefin film laminates and methods of making absorbent articles incorporating the same

Abstract

A latent elastic film laminate is provided including a film predominantly comprising olefin elastomers. The film is stretched and maintained in a stretched state in order to impart the desired level of latent elasticity such that the conditioned film laminate will shrink upon activation, such as by heating. The latent elastic film laminate can be advantageously used in the manufacture of various elasticated articles, including absorbent personal care articles, by activating the latent elasticity after attachment to the article and thereby shining and elasticizing components to which the film laminate is attached.

1 . A heat shrinkable composite material comprising:
 an elastic film having a polymeric portion and wherein the polymeric portion comprises at least 90% semi-crystalline polyolefin polymer;   a support layer intermittently bonded to said elastic film;   wherein the composite material has a % heat shrinkage greater than 15% at 72° C.   
     
     
         2 . The heat shrinkable composite material of  claim 1  wherein the polymeric portion of the elastic film comprises at least 95% by wt. semi-crystalline polyolefin polymer. 
     
     
         3 . The heat shrinkable composite material of  claim 1  wherein the semi-crystalline polyolefin polymer comprises a blend of an ethylene semi-crystalline polymer having a density between about 0.85 g/cm 3  and 0.89 g/cm 3  and a propylene semi-crystalline polymer having a density between about 0.85 g/cm 3  and 0.89 g/cm 3 . 
     
     
         4 . The heat shrinkable composite material of  claim 3  wherein the ethylene semi-crystalline polymer comprises about 80% to 99% of the polymeric portion of the film and the propylene semi-crystalline polymer comprises about 20% to 1% by wt. of the polymeric portion of the film. 
     
     
         5 . The heat shrinkable composite material of  claim 3  wherein the propylene semi-crystalline polymer comprises about 80% to 99% of the polymeric portion of the film and the ethylene semi-crystalline polymer comprises about 20% to about 1% by wt. of the polymeric portion of the film. 
     
     
         6 . The heat shrinkable composite material of any of  claim 1  wherein the film further incudes between about 0.1 and about 5% by wt. filler particles. 
     
     
         7 . The heat shrinkable composite material of  claim 1  wherein the film further includes between about 0.1 and 10% of an olefin tackifies. 
     
     
         8 . The heat shrinkable composite material of  claims 1  wherein the support layer comprises a nonwoven fabric having a basis weight between about 5 and about 20 g/M 2  and further wherein the support layer has a tensile strength greater than 50 g-f. 
     
     
         9 . The heat shrinkable composite material of  claim 1  wherein the semi-crystalline polyolefin polymer has a latent heat of fusion of between about 15 to about 75 J/g. 
     
     
         10 . The heat shrinkable composite material of  claim 1  wherein the semi-crystalline polyolefin polymer has a crystallinity between about 3 and about 30%. 
     
     
         11 . The heat shrinkable composite material of  claim 9  wherein the polymeric portion of the elastic film comprises at least 98% by wt. semi-crystalline polyolefin polymer. 
     
     
         12 . A method of making an elasticated article comprising:
 melt extruding an extrudate having a polymeric portion comprising at least 90% semi-crystalline olefin polymer;   chilling said extrudate to form a film having a temperature between about 10° C. and about 50° C.;   stretching said film between 2 times and 7 times its original length;   bonding a support fabric to said film at intermittent points while the film is in a stretched condition to form a composite material;   winding said composite material onto a winder roll under tension such that said composite material retracts less than 80% of its length at the time of said bonding step;   aging said tensioned composite material on said roll for at least 24 hours thereby forming a heat shrinkable composite material;   attaching the heat shrinkable composite material to at least one component of an article at two locations distal to one another and thereby forming distal points of attachment;   applying heat to said heat shrinkable composite material wherein the composite material shrinks and acts to pull inwardly between said distal points of attachment and cause the distal points of attachment to move closer to one another and create an elasticized region within said article.   
     
     
         13 . The method of  claim 12  wherein said extrudate comprises greater than 50% by weight propylene polymer and further wherein said at a temperature of said film at the onset of stretching is between about 21° C. and about 10° C. 
     
     
         14 . The method of  claim 12  wherein said extrudate comprises greater than 50% by weight ethylene polymer and further wherein said at a temperature of said film at the onset of stretching is between about 32° C. and about 10° C. 
     
     
         15 . The method of  claim 12  wherein said stretched film is bonded to a support fabric comprising a nonwoven fabric and having a basis weight between about 5 g/M 2  and about 20 g/M 2  and a tensile strength of at least about 50 g-f. 
     
     
         16 . The method of  claim 12  wherein said article comprises an absorbent personal care article having a liquid permeable body-facing topsheet, a liquid impermeable backsheet and an absorbent core between said topsheet and backsheet. 
     
     
         17 . The method of  claim 16  wherein said heat shrinkable composite material is attached to at least one of said topsheet and backsheet. 
     
     
         18 . The method of  claim 17  wherein the polymeric portion of the extrudate comprises at least 95% by wt. semi-crystalline polyolefin polymer selected from the group consisting of ethylene semi-crystalline polymers having a density between about 0.85 g/cm 3  and 0.89 g/cm 3  and a propylene semi-crystalline polymers having a density between about 0.85 g/cm 3  and 0.89 g/cm 3 . 
     
     
         19 . The method of  claim 18  wherein the polymeric portion of the extrudate comprises at least about 95% of a semi-crystalline olefin polymer having a crystallinity between about 3 and about 30%. 
     
     
         20 . The method of  claim 17  wherein the heat shrinkable film shrinks between about 15% and about 50% upon applying heat to shrink the composite material and pull inwardly between said distal points of attachment.