Biodegradable multicomponent fibers
View Patent ↗A multicomponent fiber that contains a high-melting aliphatic polyester and a low-melting aliphatic polyester is provided. The multicomponent fibers are substantially biodegradable, yet readily processed into nonwoven structures that exhibit effective fibrous mechanical properties.
1. A biodegradable multicomponent fiber comprising:
a first component that contains at least one high-melting point aliphatic polyester having a melting point of from about 160° C. to about 250° C.;
a second component that contains at least one low-melting point aliphatic polyester, the melting point of the low-melting point aliphatic polyester being at least about 30° C. less than the melting point of the high-melting point aliphatic polyester, wherein the low-melting point aliphatic polyester has a number average molecular weight of from about 30,000 to about 120,000 Daltons and an apparent viscosity of from about 50 to about 215 Pascal-seconds, as determined at a temperature of 160° C. and a shear rate of 1000 sec −1 , wherein the second component is free of a multicarboxylic acid nucleating agent.
2. The biodegradable multicomponent fiber of claim 1 , wherein the high-melting point aliphatic polyester has a melting point of from about 180° C. to about 220° C.
3. The biodegradable multicomponent fiber of claim 1 , wherein the high-melting point aliphatic polyester is polylactic acid.
4. The biodegradable multicomponent fiber of claim 1 , wherein the low-melting point aliphatic polyester has an apparent viscosity of from about 75 to about 200 Pascal-seconds, as determined at a temperature of 160° C. and a shear rate of 1000 sec −1 .
5. The biodegradable multicomponent fiber of claim 1 , wherein the low-melting point aliphatic polyester has an apparent viscosity of from about 80 to about 150 Pascal-seconds, as determined at a temperature of 160° C. and a shear rate of 1000 sec −1 .
6. The biodegradable multicomponent fiber of claim 1 , wherein the low-melting point aliphatic polyester has a melting point at least about 40° C. less than the melting point of the high-melting point aliphatic polyester.
7. The biodegradable multicomponent fiber of claim 1 , wherein the low-melting point aliphatic polyester has a melting point of from about 120° C. to about 160° C.
8. The biodegradable multicomponent fiber of claim 1 , wherein the low-melting point aliphatic polyester has a number average molecular weight of from about 40,000 to about 100,000 Daltons.
9. The biodegradable multicomponent fiber of claim 1 , wherein the low-melting point aliphatic polyester has a polydispersity index of from about 1.0 to about 3.0.
10. The biodegradable multicomponent fiber of claim 1 , wherein the low-melt point aliphatic polyester has a melt flow index of from about 20 to about 120 grams per 10 minutes, measured at a force of 2160 grams and temperature of 190° C. in accordance with ASTM Test Method D1238-E.
11. The biodegradable multicomponent fiber of claim 1 , wherein the fiber has a tenacity of from about 0.75 to about 7.0 grams-force per denier.
12. The biodegradable multicomponent fiber of claim 1 , wherein the fiber has a peak tensile stress of from about 150 to about 500 Megapascals.
13. The biodegradable multicomponent fiber of claim 1 , wherein the fiber has a peak tensile stress of from about 200 to about 400 Megapascals.
14. The biodegradable multicomponent fiber of claim 1 , wherein the low-melting point aliphatic polyester has a glass transition temperature of less than about 50° C.
15. The biodegradable multicomponent fiber of claim 1 , wherein the low-melting point aliphatic polyester has a glass transition temperature of less than about 0° C.
16. The biodegradable multicomponent fiber of claim 1 , wherein the low-melting point aliphatic polyester has a glass transition temperature of less than about −10° C.
17. The biodegradable multicomponent fiber of claim 1 , wherein the low-melting point aliphatic polyester contains from about 10 mol. % to about 40 mol. % of an aromatic monomer constituent.
18. The biodegradable multicomponent fiber of claim 1 , wherein the aliphatic polyester constitutes at least about 95 wt. % of the second component.
19. The biodegradable multicomponent fiber of claim 1 , wherein the low-melting point aliphatic polyester is polybutylene succinate.
20. The biodegradable multicomponent fiber of claim 1 , wherein the fiber has a sheath/core or side-by-side configuration.
21. A method for forming the multicomponent fiber of claim 1 , the method comprising:
extruding a first thermoplastic composition, the first thermoplastic composition comprising the high-melting point aliphatic polyester; and
extruding a second thermoplastic composition, the second thermoplastic composition comprising the low-melting point aliphatic polyester, wherein the second thermoplastic composition is extruded at a temperature ranging from about 120° C. to about 200° C.; and
quenching the extruded thermoplastic compositions; and
drawing the extruded and quenched thermoplastic compositions.
22. The method of claim 21 , wherein the second thermoplastic composition is extruded at a temperature ranging from about 145° C. to about 195° C.
23. The method of claim 21 , wherein the fiber is drawn at a ratio of from about 200:1 to about 6000:1.
24. A nonwoven web comprising biodegradable multicomponent fibers, wherein the multicomponent fibers comprise:
a first component that contains at least one high-melting point aliphatic polyester having a melting point of from about 160° C. to about 250° C.;
a second component that contains at least one low-melting point aliphatic polyester, the melting point of the low-melting point aliphatic polyester being at least about 40° C. less than the melting point of the high-melting point aliphatic polyester, wherein the low-melting point aliphatic polyester has a number average molecular weight of from about 30,000 to about 120,000 Daltons and an apparent viscosity of from about 50 to about 215 Pascal-seconds, as determined at a temperature of 160° C. and a shear rate of 1000 sec −1 , wherein the second component is free of a multicarboxylic acid nucleating agent.
25. The nonwoven web of claim 24 , wherein the high-melting point aliphatic polyester has a melting point of from about 180° C. to about 220° C.
26. The nonwoven web of claim 24 , wherein the high-melting point aliphatic polyester is polylactic acid.
27. The nonwoven web of claim 24 , wherein the low-melting point aliphatic polyester has an apparent viscosity of from about 75 to about 200 Pascal-seconds, as determined at a temperature of 160° C. and a shear rate of 1000 sec −1 .
28. The nonwoven web of claim 24 , wherein the low-melting point aliphatic polyester has an apparent viscosity of from about 80 to about 150 Pascal-seconds, as determined at a temperature of 160° C. and a shear rate of 1000 sec −1 .
29. The nonwoven web of claim 24 , wherein the low-melting point aliphatic polyester has a melting point of from about 120° C. to about 160° C.
30. The nonwoven web of claim 24 , wherein the low-melting point aliphatic polyester has a number average molecular weight of from about 45,000 to about 85,000 Daltons.
31. The nonwoven web of claim 24 , wherein the low-melting point aliphatic polyester is polybutylene succinate.
32. The nonwoven web of claim 24 , wherein the fibers have a peak tensile stress of from about 150 to about 500 Megapascals.
33. The nonwoven web of claim 24 , wherein the fibers have a peak tensile stress of from about 200 to about 400 Megapascals.
34. An absorbent article comprising a substantially liquid-impermeable layer, a liquid-permeable layer, and an absorbent core, wherein the absorbent core, the liquid-permeable layer, or both comprise the nonwoven web of claim 24 .
35. The biodegradable multicomponent fiber of claim 1 , wherein the low-melting point aliphatic polyester has a number average molecular weight of from about 45,000 to about 85,000 Daltons.
36. The nonwoven web of claim 24 , wherein the low-melting point aliphatic polyester has a number average molecular weight of from about 45,000 to about 85,000 Daltons.