Multilayer stretchy drawstring
View Patent ↗The disclosed subject matter relates to a multilayer stretchy drawstring and methods of making the same. The drawstring of the disclosed subject matter is a stretched multilayer coextruded or laminated film that offers good balance between easy stretching at low strain and high strain hardening at high strain. The multilayer film includes a first layer of elastomeric polymer and second and third layers of thermoplastic polymer and is stretched beyond the deformation limit of the thermoplastic polymer and allowed to recover. This novel drawstring can be incorporated into a bag to enable the bag to be securely fitted to the upper portion of a trash container while not interfering with the intrinsic strength and operation of the drawstring.
1. A drawstring bag comprising:
first and second thermoplastic body panels joined along a pair of opposing sides and a bottom bridging the opposing sides, the joined first and second body panels defining a mouth disposed opposite the bottom;
a drawstring comprising a first layer of elastomeric polymer, a second layer of thermoplastic polymer, and a third layer of thermoplastic polymer, the thermoplastic polymer of the second layer and of the third layer each having a deformation limit, the second layer and the third layer being disposed on opposite sides of the first layer, wherein the drawstring is stretched beyond the deformation limit of the thermoplastic polymer of the second layer and the third layer respectively and allowed to elastically recover, the drawstring has a tensile strength of at least 22 lbs;
the drawstring being disposed proximate the mouth of the bag.
2. The drawstring bag of claim 1 , wherein the drawstring is affixed proximate the mouth of the bag.
3. The drawstring bag of claim 2 , wherein the drawstring is affixed by thermal sealing.
4. The drawstring bag of claim 1 , comprising:
at least one of the first and second thermoplastic body panels further defines a hem extending along the mouth of the bag; and
the drawstring being disposed within the hem.
5. The drawstring bag of claim 1 , wherein the first layer of elastomeric polymer includes ethylene-octene copolymer.
6. The drawstring bag of claim 1 , wherein the first layer of elastomeric polymer includes ethylene-propylene copolymer.
7. The drawstring bag of claim 1 , wherein the second layer of thermoplastic polymer includes linear low density polyethylene.
8. The drawstring bag of claim 1 , wherein the second layer of thermoplastic polymer includes high density polyethylene.
9. The drawstring bag of claim 1 , wherein following recovery, an outer surface of the drawstring is substantially smooth.
10. The drawstring bag of claim 1 , wherein the drawstring is uniaxially stretched.
11. The drawstring bag of claim 1 , wherein the drawstring is biaxially stretched.
12. The drawstring bag of claim 1 , wherein the drawstring is between about 30 and 70 percent by volume of the first layer of elastomeric polymer.
13. The drawstring bag of claim 1 , wherein the drawstring is between about 40 and 70 percent by volume of the first layer of elastomeric polymer.
14. The drawstring bag of claim 1 , wherein the drawstring is between about 45 and 65 percent by volume of the first layer of elastomeric polymer.
15. The drawstring bag of claim 1 , wherein the drawstring is a laminate of the first, second, and third layers.
16. The drawstring bag of claim 1 , wherein the drawstring is formed by coextruding the first, second, and third layers.
17. The drawstring bag of claim 1 , wherein the thermoplastic polymer of the second layer and the thermoplastic polymer of the third layer are the same polymer.
18. A drawstring comprising:
a first layer of elastomeric polymer, a second layer of thermoplastic polymer, and a third layer of thermoplastic polymer, the thermoplastic polymer of the second layer and of the third layer each having a deformation limit, the second layer and the third layer being disposed on opposite sides of the first layer, wherein the drawstring is stretched beyond the deformation limit of the thermoplastic polymer of the second layer and the third layer respectively and allowed to elastically recover, the drawstring has a tensile strength of at least 22 lbs.
19. The drawstring of claim 18 , wherein the first layer of elastomeric polymer includes ethylene-octene copolymer.
20. The drawstring of claim 18 , wherein the first layer of elastomeric polymer includes ethylene-propylene copolymer.
21. The drawstring of claim 18 , wherein the second layer of thermoplastic polymer includes linear low density polyethylene.
22. The drawstring of claim 18 , wherein the second layer of thermoplastic polymer includes high density polyethylene.
23. The drawstring of claim 18 , wherein following recovery, an outer surface of the drawstring is substantially smooth.
24. The drawstring of claim 18 , wherein the drawstring is uniaxially stretched.
25. The drawstring of claim 18 , wherein the drawstring is biaxially stretched.
26. The drawstring of claim 18 , wherein the drawstring is between about 30 and 70 percent by volume of the first layer of elastomeric polymer.
27. The drawstring of claim 18 , wherein the drawstring is between about 40 and 70 percent by volume of the first layer of elastomeric polymer.
28. The drawstring of claim 18 , wherein the drawstring is between about 45 and 65 percent by volume of the first layer of elastomeric polymer.
29. The drawstring of claim 18 , wherein the drawstring is a laminate of the first, second, and third layers.
30. The drawstring of claim 18 , wherein the drawstring is formed by coextruding the first, second, and third layers.
31. The drawstring of claim 18 , wherein the thermoplastic polymer of the second layer and the thermoplastic polymer of the third layer are the same polymer.