High performance elastic laminates made from high molecular weight styrenic tetrablock copolymer
View Patent ↗An elastic laminate is provided which has an elastic layer and one or two outer facing layers. The elastic layer is formed from an improved styrene-(ethylene-butylene)-styrene-(ethylene-butylene) tetrablock copolymer, or a blend of the copolymer. The copolymer has a number average molecular weight of at least about 70,000. The two ethylene-butylene blocks have number average molecular weights which together constitute more than 75% of the number average molecular weight of the copolymer.
1. An elastic laminate, comprising:
an elastic layer including about 25-100% by weight of a SEBSEB copolymer; and
at least one facing layer comprising a fibrous thermoplastic nonwoven web, bonded to the elastic layer;
the SEBSEB copolymer having a number average molecular weight of at least about 70,000 and including a styrene end block, an ethylene-butylene midblock, a styrene midblock, and an ethylene-butylene end block;
the ethylene-butylene blocks having number average molecular weights which together constitute more than 75% of the number average molecular weight for the SEBSEB copolymer;
the styrene midblock having a number average molecular weight about 5-50% higher than a number average molecular weight of the styrene end block.
2. The elastic laminate of claim 1 , comprising a stretch-bonded laminate.
3. The elastic laminate of claim 2 , comprising a vertical filament laminate.
4. The elastic laminate of claim 1 , comprising a neck-bonded laminate.
5. The elastic laminate of claim 4 , comprising a neck-stretch bonded laminate.
6. The elastic laminate of claim 1 , comprising two of the facing layers bonded on both sides of the elastic layer.
7. The elastic laminate of claim 1 , wherein the elastic layer comprises an array of substantially parallel, nonintersecting filaments.
8. The elastic laminate of claim 1 , wherein the elastic layer comprises a film.
9. The elastic laminate of claim 1 , wherein the elastic layer comprises a foam.
10. The elastic laminate of claim 1 , wherein the elastic layer comprises a fibrous nonwoven web.
11. The elastic laminate of claim 1 , wherein the elastic layer comprises a net.
12. The elastic laminate of claim 1 , wherein the SEBSEB copolymer has a number average molecular weight of about 73,000 to about 100,000.
13. The elastic laminate of claim 1 , wherein the elastic layer further comprises a poly(monoalkenyl arene).
14. The elastic laminate of claim 13 , wherein the elastic layer further comprises a polyolefin.
15. The elastic laminate of claim 14 , wherein the elastic layer further comprises a tackifying resin.
16. An elastic laminate, comprising:
an elastic layer including about 50-80% by weight of a SEBSEB copolymer, about 4-15% by weight of a poly(monoalkenyl arene), about 5-20% by weight of a polyolefin, and zero to about 25% by weight of a tackifying resin; and
at least one fibrous thermoplastic nonwoven facing layer bonded to the elastic layers;
the SEBSEB copolymer having a number average molecular weight of at least about 70,000 and including a styrene end block, an ethylene-butylene midblock, a styrene midblock, and an ethylene-butylene end block;
the styrene midblock having a number average molecular weight about 5-50% higher than a number average molecular weight of the styrene end block.
17. The elastic laminate of claim 16 , comprising two of the facing layers bonded on both sides of the elastic layer.
18. The elastic laminate of claim 16 , wherein the elastic layer includes about 65-75% by weight of the SEBSEB copolymer, about 5-10% by weight of the poly(monoalkenyl arene), about 5-15% by weight of the polyolefin, and about 10-25% by weight of the tackifying resin.
19. The elastic laminate of claim 16 , wherein the SEBSEB copolymer has a number average molecular weight of about 70,000 to about 120,000.
20. The elastic laminate of claim 16 , wherein the poly(monoalkenyl arene) comprises polystyrene.
21. The elastic laminate of claim 16 , wherein the polyolefin comprises a polyethylene wax.
22. The elastic laminate of claim 16 , wherein the tackifying resin comprises a hydrocarbon resin selected from low molecular weight hydrogenated polystyrene, low molecular weight hydrogenated poly-alphamethyl styrene, and combinations thereof.
23. The elastic laminate of claim 16 , wherein the facing layer comprises a fibrous nonwoven web.
24. The elastic laminate of claim 16 , wherein the elastic layer comprises an array of substantially parallel, nonintersecting filaments.
25. The elastic laminate of claim 16 , wherein the elastic layer comprises a film.
26. The elastic laminate of claim 16 , wherein the elastic layer comprises a foam.
27. The elastic laminate of claim 16 , wherein the elastic layer comprises a net.
28. The elastic laminate of claim 16 , wherein the elastic layer comprises a fibrous nonwoven web.
29. A disposable garment comprising the elastic laminate of claim 16 .
30. A disposable infection control product comprising the elastic laminate of claim 16 .
31. A disposable personal care product comprising the elastic laminate of claim 16 .
32. An elastic laminate, comprising:
an elastic layer including about 25-100% by weight of a SEBSEB copolymer, zero to about 25% by weight of a poly(monoalkenyl arene), zero to about 25% by weight of a polyolefin, and zero to about 25% by weight of a tackifying resin; and
two nonwoven facing layers bonded to the elastic layer;
the SEBSEB copolymer having a number average molecular weight of at least about 70,000 and including a styrene end block, an ethylene-butylene midblock, a styrene midblock, and an ethylene-butylene end block, each of the blocks having a number average molecular weight;
the number average molecular weight of the styrene midblock being at least about 5% higher than the number average molecular weight of the styrene end block.
33. The elastic laminate of claim 32 , wherein the number average molecular weight of the styrene midblock is about 10-50% higher than the number average molecular weight of the styrene end block.
34. The elastic laminate of claim 32 , wherein the number average molecular weight of the styrene midblock is about 15-35% higher than the number average molecular weight of the styrene end block.
35. The elastic laminate of claim 32 , wherein:
the styrene end block has a number average molecular weight of about 6,000 to about 8,000;
the styrene midblock has a number average molecular weight of about 7,500 to about 9,000;
the ethylene-butylene midblock has a number average molecular weight of about 55,000 to about 70,000; and
the ethylene-butylene end block has a number average molecular weight of about 5,000 to about 12,000.
36. The elastic laminate of claim 32 , wherein the elastic layer includes about 50-80% by weight of the SEBSEB copolymer.
37. The elastic laminate of claim 32 , wherein the elastic layer includes about 4-15% by weight of the poly(monoalkenyl arene).
38. The elastic laminate of claim 32 , wherein the elastic layer includes about 5-20% by weight of the polyolefin.
39. The elastic laminate of claim 32 , wherein the elastic layer includes about 10-25% by weight of the tackifying resin.
40. A disposable garment comprising the elastic laminate of claim 32 .
41. A disposable infection control product comprising the elastic laminate of claim 32 .
42. A disposable personal care product comprising the elastic laminate of claim 32 .
43. The elastic laminate of claim 32 , wherein the nonwoven facing layers comprise spunbond webs.
44. The elastic laminate of claim 32 , wherein the elastic layer comprises an array of substantially continuous, nonintersecting filaments.
45. The elastic laminate of claim 44 , comprising a stretch-bonded laminate.
46. The elastic laminate of claim 32 , wherein the elastic layer comprises a material selected from a film, foam, fibrous nonwoven web, and combinations thereof.
47. The elastic laminate of claim 46 , comprising a neck-bonded laminate.
48. The elastic laminate of claim 46 , comprising a stretch-bonded laminate.
49. The elastic laminate of claim 46 , comprising a neck-stretch bonded laminate.
50. An elastic laminate, comprising:
an elastic layer including about 25-100% by weight of a SEBSEB tetrablock copolymer; and
at least one fibrous thermoplastic nonwoven facing layer bonded to the elastic layer;
wherein the elastic layer is formed of an elastic polymer composition having an elastic modulus at least 10% higher than for a control polymer composition including 80% by weight styrene-(ethylene-propylene)-styrene-(ethylene-propylene) tetrablock copolymer, 7% by weight polyethylene wax, and 13% by weight tackifying resin;
the SEBSEB copolymer having a number average molecular weight of at least about 70,000 and including a styrene end block, an ethylene-butylene midblock, a styrene midblock, and an ethylene-butylene end block;
the styrene midblock having a number average molecular weight about 5-50% higher than a number average molecular weight of the styrene end block.
51. The elastic laminate of claim 50 , wherein the elastic modulus for the elastic polymer composition is at least 25% higher than for the control polymer composition.
52. An elastic laminate, comprising:
an elastic layer including about 25-100% by weight of a SEBSEB tetrablock copolymer; and
at least one fibrous thermoplastic nonwoven facing layer bonded to the elastic layer;
wherein the elastic layer is formed of an elastic polymer composition having a stress at 50% elongation at least 5% higher than for a control polymer composition including 80% by weight styrene-(ethylene-propylene)-styrene-(ethylene-propylene) tetrablock copolymer, 7% by weight polyethylene wax, and 13% by weight tackifying resin;
the SEBSEB copolymer having a number average molecular weight of at least about 70,000 and including a styrene end block, an ethylene-butylene midblock, a styrene midblock, and an ethylene-butylene end block;
the styrene midblock having a number average molecular weight about 5-50% higher than a number average molecular weight of the styrene end block.
53. The elastic laminate of claim 52 , wherein the stress at 50% elongation for the elastic polymer composition is at least 15% higher than for the control polymer composition.
54. An elastic laminate, comprising:
an elastic layer including about 25-100% by weight of a SEBSEB tetrablock copolymer; and
at least one fibrous thermoplastic nonwoven facing layer bonded to the elastic layer;
wherein the elastic layer is formed of an elastic polymer composition having an elongation at break at least 10% higher than for a control polymer composition including 80% by weight styrene-(ethylene-propylene)-styrene-(ethylene-propylene) tetrablock copolymer, 7% by weight polyethylene wax, and 13% by weight tackifying resin;
the SEBSEB copolymer having a number average molecular weight of at least about 70,000 and including a styrene end block, an ethylene-butylene midblock, a styrene midblock, and an ethylene-butylene end block;
the styrene midblock having a number average molecular weight about 5-50% higher than a number average molecular weight of the styrene end block.
55. The elastic laminate of claim 54 , wherein the elastic polymer composition has a stress at break at least 40% higher than for the control polymer composition.
56. The elastic laminate of claim 55 , wherein the stress at break for the elastic polymer composition is at least 100% higher than for the control polymer composition.