Multicomponent Biodegradable Filaments and Nonwoven Webs Formed Therefrom
A biodegradable, substantially continuous filament is provided. The filament contains a first component formed from at least one high melting polyester and a second component formed from at least one low melting polyester. The low melting point polyester is an aliphatic-aromatic copolyester formed by melt blending a polymer and an alcohol to initiate an alcoholysis reaction that results in a copolyester having one or more hydroxyalkyl or alkyl terminal groups. By selectively controlling the alcoholysis conditions (e.g., alcohol and copolymer concentrations, catalysts, temperature, etc.), a modified aliphatic-aromatic copolyester may be achieved that has a molecular weight lower than the starting aliphatic-aromatic polymer. Such lower molecular weight polymers also have the combination of a higher melt flow index and lower apparent viscosity, which is useful in the formation of substantially continuous filaments.
1 . A biodegradable, substantially continuous multicomponent filament comprising a first component and a second component, the first component containing a first polyester having a melting point of from about 150° C. to about 250° C. and the second component containing a second polyester, wherein the second polyester is an aliphatic-aromatic copolyester terminated with an alkyl group, hydroxyalkyl group, or a combination thereof, the aliphatic-aromatic copolyester having a melt flow index of from about 5 to about 200 grams per 10 minutes, determined at a load of 2160 grams and temperature of 190° C. in accordance with ASTM Test Method D1238-E.
2 . The biodegradable filament of claim 1 , wherein the melt flow index of the copolyester is from about 15 to about 50 grams per 10 minutes.
3 . The biodegradable filament of claim 1 , wherein the copolyester has a number average molecular weight of from about 10,000 to about 70,000 grams per mole and a weight average molecular weight of from about 20,000 to about 125,000 grams per mole.
4 . The biodegradable filament of claim 1 , wherein the copolyester has a number average molecular weight of from about 20,000 to about 60,000 grams per mole and a weight average molecular weight of from about 30,000 to about 110,000 grams per mole.
5 . The biodegradable filament of claim 1 , wherein the copolyester has a melting point of from about 50° C. to about 150° C.
6 . The biodegradable filament of claim 1 , wherein the copolyester has a glass transition temperature of about 0° C. or less.
7 . The biodegradable filament of claim 1 , wherein the copolyester has the following general structure:
wherein,
m is an integer from 2 to 10, in some embodiments from 2 to 4, and in one embodiment, 4;
n is an integer from 0 to 18, in some embodiments from 2 to 4, and in one embodiment, 4;
p is an integer from 2 to 10, in some embodiments from 2 to 4, and in one embodiment, 4;
x is an integer greater than 1;
y is an integer greater than 1; and
R 1 and R 2 are independently selected from hydrogen; hydroxyl groups; straight chain or branched, substituted or unsubstituted C 1 -C 10 alkyl groups; and straight chain or branched, substituted or unsubstituted C 1 -C 10 hydroxalkyl groups.
8 . The biodegradable filament of claim 7 , wherein m and n are each from 2 to 4.
9 . The biodegradable filament of claim 7 , wherein the copolyester is derived from polybutylene adipate terephalate.
10 . The biodegradable filament of claim 1 , wherein the first polyester is polylactic acid.
11 . The biodegradable filament of claim 1 , wherein the filament has a sheath/core or side-by-side configuration.
12 . A nonwoven web comprising the biodegradable filament of claim 1 .
13 . An absorbent article comprising an absorbent core positioned between a substantially liquid-impermeable layer and a liquid-permeable layer, wherein the substantially liquid-impermeable layer contains the nonwoven web of claim 12 .
14 . The absorbent article of claim 13 , wherein the substantially liquid-impermeable layer forms an outer cover of the absorbent article.
15 . The absorbent article of claim 14 , wherein the nonwoven web is laminated to a breathable film.
16 - 37 . (canceled)