Elastic film laminates prepared by multiple stretching steps
View Patent ↗Elastic laminates and methods of making same are provided, wherein the laminate includes an elastic film laminated to at least one substrate web, and wherein the elastic film has been stretched at least twice prior to bonding the film to the substrate layer. Such laminates possess improved bond strength between the film and the substrate web and have greater elongation versus laminates made with a film that has been stretched only once.
1. A process of manufacturing a laminate, the process comprising:
providing an elastic film comprising a styrene/isoprene/styrene core and one or more skin layers of a polyethylene polymer;
stretching the film in the machine direction to a 4:1 draw ratio or greater in a first stretching step;
relaxing the film after the first stretching step;
perforating the film after relaxing the film;
stretching the film at least once more in the machine direction less than the draw ratio after perforating the film in a second stretching step such that the film is stretched less in the second stretching step than in the first stretching step;
laminating the film to at least one substrate web while the film is stretched in the second stretching step to form a laminate; and
relaxing the laminate.
2. The process of claim 1 , wherein the second stretching step comprises laminating the film to at least one nonwoven web.
3. The process of claim 1 , wherein the elastic film comprises an elastic core and at least one skin layer.
4. The process of claim 3 , wherein providing the elastic film comprises co-extruding an elastic film having an elastic core and at least two skin layers.
5. The process of claim 1 , wherein providing the elastic film, stretching the film in the first stretching step, relaxing the film after the first stretching step and perforating the film after relaxation are performed by a film manufacturer when stretching the film in the second stretching step, laminating the film, and relaxing the laminate are performed by an article manufacturer.
6. The process of claim 5 , wherein at least a portion of stretching the film in the second stretching step, laminating the film, or relaxing the laminate involve the use of a cut-and-place apparatus.
7. The process of claim 1 , further comprising:
winding the film after perforation; and
unwinding the film prior to the second stretching step.
8. The process of claim 1 , wherein at least one of the following: stretching the film in the first stretching step or stretching the film in the second stretching step comprises intermittently stretching the film.
9. The process of claim 8 , wherein stretching the film in the first stretching step comprises intermittently stretching the film.
10. The process of claim 9 , wherein the film is intermittently stretched using intermeshing gear stretching.
11. The process of claim 8 , wherein stretching the film in the second stretching step comprises intermittently stretching the film.
12. The process of claim 8 , wherein the film is intermittently stretched in a machine direction using intermeshing gear stretching in the first stretching step and wherein the intermittent stretching in the second stretching step comprises alternately gripping the film with a ribbed roller such that the film is alternately placed under tension in the machine direction and stretched between the ribbed roller and a downstream nip operating at a greater rotation speed as compared to the ribbed roller.
13. A process of manufacturing a laminate, the process comprising: providing an elastic film comprising a styrene/isoprene/styrene core and one or more skin layers of a polyethylene polymer;
intermittently stretching the film in the machine direction to a 4:1 draw ratio or greater in a first stretching step;
relaxing the film after the first stretching step;
perforating the film after relaxing the film;
intermittently stretching the film at least once more in the machine direction less than the draw ratio after perforating the film in a second stretching step such that the film is stretched less in the second stretching step than in the first stretching step;
laminating the film to at least one substrate web while the film is stretched in the second stretching step to form a laminate; and
relaxing the laminate.
14. The process of claim 13 , wherein the second stretching step comprises laminating the film to at least one nonwoven web.
15. The process of claim 13 , wherein the elastic film comprises an elastic core and at least one skin layer.
16. The process of claim 15 , wherein providing the elastic film comprises co-extruding an elastic film having an elastic core and at least two skin layers.
17. The process of claim 13 , wherein providing the elastic film, intermittently stretching the film in the first stretching step, relaxing the film after the first stretching step and perforating the film after relaxation are performed by a film manufacturer when intermittently stretching the film in the second stretching step, laminating the film, and relaxing the laminate are performed by an article manufacturer.
18. The process of claim 17 , wherein at least a portion of intermittently stretching the film in the second stretching step, laminating the film, or relaxing the laminate involve the use of a cut-and-place apparatus.
19. The process of claim 13 , further comprising:
winding the film after perforation; and
unwinding the film prior to the second stretching step.
20. The process of claim 13 , wherein the film is intermittently stretched in a machine direction using intermeshing gear stretching in the first stretching step and wherein the intermittent stretching in the second stretching step comprises alternately gripping the film with a ribbed roller such that the film is alternately placed under tension in the machine direction and stretched between the ribbed roller and a downstream nip operating at a greater rotation speed as compared to the ribbed roller.