Method of making extensible web laminates
A method of making extensible web laminates comprising a multilayer film and at least one web layer and the use of such extensible web laminates in personal care articles. The method generally includes activating the multilayer film in a first direction by stretching at least a portion of the multilayer film past the elastic deformation limit of the skin layers and recovering the skin layers with the elastomeric core layer to produce a multilayer film that is elastic in the first direction. The activated multilayer film is subsequently stretched beyond the deformation limit of the skin layers in a second direction substantially perpendicular to the first direction. At least one web layer is applied to the multilayer film while in the stretched state. The multilayer film is then recovered to produce an extensible web laminate.
1. A method of making an extensible web laminate comprising:
providing a multilayer film comprising two skin layers and an elastomeric core layer sandwiched therebetween, where the multilayer film has been activated in the cross-machine direction by stretching at least a portion of the multilayer film beyond the elastic deformation limit of the skin layers and recovering the multilayer film to impart elastic extensibility to the film in the direction of stretch;
after the multilayer film has been activated in the cross-machine direction, then stretching the multilayer film past the deformation limit of the skin layers in the machine direction;
laminating a web layer to the multilayer film while it is stretched in the machine direction; and
recovering the multilayer film to produce an extensible web laminate.
2. The method of claim 1 , wherein the multilayer film that has been activated in the cross-machine direction exhibits microtextured surface structure over a least a portion of the multilayer film.
3. The method of claim 1 , wherein the multilayer film has been activated in the cross-machine direction by incremental stretching.
4. The method of claim 1 , wherein the multilayer film has been activated in the cross-machine direction by diverging disks.
5. The method of claim 1 , wherein the stretch ratio of the multilayer film during activation in the cross-machine direction was 2:1 to 5:1.
6. The method of claim 1 , wherein the multilayer film is stretched in the machine direction by differential speed rolls.
7. The method of claim 1 , wherein the multilayer film is colored and/or contains a print pattern.
8. The method of claim 1 , wherein the web layer is a nonwoven layer.
9. The method of claim 1 , further providing a second web layer that is laminated to the multilayer film while it is stretched in the machine direction, where the multilayer film is sandwiched between the two web layers.
10. The method of claim 1 , wherein the web layer is laminated to the multilayer film by adhesive bonding, thermal bonding, point bonding, ultrasonic welding or combinations thereof.
11. The method of claim 1 , wherein the web layer is laminated to the multilayer film by ultrasonic welding.
12. The method of claim 8 , further providing a second nonwoven layer that is laminated to the multilayer film while it is stretched in the machine direction, where the multilayer film is sandwiched between the two nonwoven layers.
13. The method of claim 12 , wherein each of the nonwoven layers has a different basis weight.
14. The method of claim 12 , wherein the nonwoven layers are laminated to the multilayer film by ultrasonic welding.
15. The method of claim 14 , wherein the multilayer film is apertured but the nonwoven layers are not.
16. The method of claim 14 , wherein the multilayer film and nonwoven layers are apertured.
17. The method of claim 1 , wherein the core:skin ratio of the multilayer film prior to activating the multilayer film in the cross-machine direction is at least 2:1.
18. The method of claim 1 , wherein the core:skin ratio of the multilayer film prior to activating the multilayer film in the cross-machine direction is at least 3:1.
19. The method of claim 1 , wherein the elastomeric core layer is a styrenic block copolymer and the skin layers are each a polyolefin.
20. The method of claim 1 , wherein the elastomeric core layer is a SIS and polystyrene blend and the skin layers are a polypropylene and polyethylene blend.
21. The method of claim 1 , wherein the elastomeric core layer is a SIS and polystyrene blend and the skin layers are polypropylene.
22. The method of claim 1 , wherein the multilayer film provided for stretching would require a force of at least 2.5 N to stretch a 25.4 mm wide sample 10% in the machine direction.
23. The method of claim 1 , wherein the multilayer film provided for stretching would require a force of about 5 N to 10 N to stretch a 25.4 mm wide sample 10% in the machine direction.
24. The method of claim 1 , wherein activation of the film in the cross-machine direction reduces % neck-in of the film during stretching in the machine direction by at least 1%.
25. The method of claim 1 , wherein activation of the film in the cross-machine direction reduces % neck-in of the film during stretching in the machine direction by at least 5%.
26. The method of claim 1 , wherein the extensible web laminate is incorporated into a personal care article.