Biodegradable and breathable film
View Patent ↗Breathable and biodegradable polymeric film materials of the invention are highly suitable for use in personal care absorbent articles and other articles. The film includes a biodegradable polymer resin, a thermoplastic starch, a filler and optionally, a protein. The breathable film has a renewable natural polymer component.
1. A biodegradable, breathable film comprising:
a thermoplastic starch, wherein the thermoplastic starch is present in an amount ranging from about 20% to about 30% by weight of the film;
a filler selected from inorganic fillers, organic fillers, and mixtures thereof, wherein the filler is present in an amount ranging from about 25% to about 35% by weight of the film; and
a biodegradable polymer resin comprising an aliphatic-aromatic copolyester that is polybutylene adipate terephthalate, wherein the biodegradable polymer resin is present in an amount ranging from about 39% to about 45% by weight of the film, wherein the film after stretching has a water vapor transmission rate of about 2000 g/m 2 /day to about 2800 g/m 2 /day.
2. The film of claim 1 wherein the inorganic filler is coated with a blend of stearic and palmitic acid.
3. The film of claim 1 further comprising a protein.
4. The film of claim 3 wherein the protein comprises a plant protein.
5. The film of claim 4 wherein the protein comprises gluten or soy protein.
6. The film of claim 4 wherein the plant protein ranges from 5% to about 45% by weight of the film.
7. The film of claim 1 wherein the thermoplastic starch is a thermoplastic hydroxypropyl starch.
8. The film of claim 1 wherein the inorganic and/or organic filler comprises particles having a mean size of 2 microns.
9. The film of claim 1 wherein the thermoplastic starch comprises a plasticizer.
10. The film of claim 9 wherein the plasticizer is a polyhydric alcohol.
11. The film of claim 9 wherein the plasticizer is glycerol or sorbitol.
12. The film of claim 9 wherein the plasticizer is a mixture of two or more plasticizers.
13. The film of claim 1 , wherein the film has a percent elongation in the machine direction ranging from 176% to 464%.
14. An article comprising the film of claim 1 as a drape sheet.
15. An absorbent article comprising the film of claim 1 wherein the film is configured to be a backsheet.
16. The absorbent article of claim 15 comprising an absorbent core disposed between the backsheet and a body-side liner attached to the backsheet.
17. A method for manufacturing a biodegradable, breathable film comprising the steps of:
a) forming a thermoplastic resin from a starch, a modified starch, or a mixture of starch and plant protein, wherein the thermoplastic resin is present in the film in an amount ranging from about 20% to about 30% by weight of the film;
b) melt blending the thermoplastic resin with a filler selected from inorganic fillers, organic fillers, and mixtures thereof, wherein the filler is present in an amount ranging from about 25% to about 35% by weight of the film, and a biodegradable polymer resin comprising an aliphatic-aromatic copolyester that is polybutylene adipate terephthalate, wherein the biodegradable polymer resin is present in the film in an amount ranging from about 39% to about 45% by weight of the film; and
c) extruding the film from the melt blend to form a film; and
d) stretching the film wherein the film after stretching has a water vapor transmission rate of about 2000 g/m 2 /day to about 2800 g/m 2 /day.
18. The method of claim 17 , wherein the film has a percent elongation in the machine direction ranging from 176% to 464%.