Film formed from a blend of biodegradable aliphatic-aromatic copolyesters
View Patent ↗A film that is formed from a biodegradable polymer blend of different aliphatic-aromatic copolyesters is provided. More specifically, the blend contains a first copolyester formed from a terephthalic acid monomer. The use of a terephthalic acid monomer results in a polymer chain containing 1,4-(para-)terephthalate units linked in a generally linear configuration (e.g., ˜180°). The blend also contains a second aliphatic-aromatic copolyester formed from a phthalic acid and/or isophthalic acid monomer.
1. A laminate comprising:
a nonwoven web material; and
a film joined to the nonwoven web material, wherein the film comprises a biodegradable polymer blend, the biodegradable polymer blend containing from about 15 wt. % to about 85 wt. % of a first aliphatic-aromatic copolyester and from about 15 wt. % to about 85 wt. % of a second aliphatic-aromatic copolyester, wherein the first aliphatic-aromatic copolyester is formed from a first aromatic monomer that includes terephthalic acid or a derivative thereof and the second aliphatic-aromatic copolyester is formed from a second aromatic monomer that includes phthalic acid or a derivative thereof, isophthalic acid or a derivative thereof, or a combination of the foregoing, wherein the glass transition temperature of the first aliphatic-aromatic copolyester and the second aliphatic-aromatic copolyester is about 0° C or less, and wherein the film exhibits a water vapor transition rate of from about 800 to about 10,000 grams/m 2 -24 hours.
2. The laminate of claim 1 , wherein the first aliphatic-aromatic copolyester has a linear chain configuration and the second aliphatic-aromatic copolyester has a kinked chain configuration.
3. The laminate of claim 1 , wherein the first aliphatic-aromatic copolyester constitutes from about 25 wt. % to about 75 wt. % of the polymer blend and the second aliphatic-aromatic copolyester constitutes from about 25 wt. % to about 75 wt. % of the polymer blend.
4. The laminate of claim 1 , wherein the first aromatic monomer includes terephthalic acid.
5. The laminate of claim 1 , wherein the first aliphatic-aromatic copolyester is represented by the following structure:
wherein,
m is an integer from 2 to 10;
n is an integer from 0 to 18;
p is an integer from 2 to 10;
x is an integer greater than 1; and
y is an integer greater than 1.
6. The laminate of claim 1 , wherein the first aliphatic-aromatic copolyester is polybutylene adipate terephthalate.
7. The laminate of claim 1 , wherein the second aromatic monomer includes isophthalic acid or an ester thereof.
8. The laminate of claim 7 , wherein the second aromatic monomer includes an alkyl isophthalate.
9. The laminate of claim 1 , wherein the second aliphatic-aromatic copolyester is represented by the following general structure:
wherein,
m is an integer from 2 to 10;
n is an integer from 0 to 18;
p is an integer from 2 to 10;
r is an integer greater than 1; and
s is an integer greater than 1.
10. The laminate of claim 1 , wherein the second aliphatic-aromatic copolyester is polyethylene adipate isophthalate or polybutylene adipate isophthalate.
11. The laminate of claim 1 , wherein the first aliphatic-aromatic copolyester has a melting point of from about 80° C. to about 140° C. and the second aliphatic-aromatic copolyester has a melting point of from about 50° C. to about 160° C.
12. The laminate of claim 1 , wherein the blend further includes an aliphatic polyester.
13. The laminate of claim 1 , wherein the film is microporous.