Fibrillated polyolefin foam
View Patent ↗A method for generating a thermoplastic foam from an aqueous dispersion, the aqueous dispersion comprising a thermoplastic resin, water, and a dispersion stabilizing agent, the method including: adding at least one froth stabilizing surfactant to the aqueous dispersion to form a mixture; adding a fiber to the mixture; and frothing the mixture to create a froth, removing at least a portion of the water in the froth to create a foam, wherein the foam generated has a non-cellular fibrillated morphology. In another aspect, embodiments disclosed herein relate to a foam having a thermoplastic-based, fibrillated, non-cellular structure, wherein the foam has an average density of about 0.02 g/cm 3 to about 0.07 g/cm 3 . In certain embodiments, the foam may be used in an absorbent article.
1. A method for generating a thermoplastic non-cellular fibrillated foam, the method comprising:
melting a thermoplastic resin and dispersion stabilizing agent in a fist part of an extruder to form a polymer melt;
adding water to the polymer melt to form an aqueous dispersion in a second part of the extruder;
adjusting the pH of the aqueous dispersion to between 8 and 11;
adding at least one froth stabilizing surfactant to the aqueous dispersion to form a mixture;
adding fiber to the mixture,
wherein the fiber comprises at least one of a polyethylene homopolymer, copolymer, or multiblock interpolymer, a polypropylene homopolymer, copolymer, or multiblock interpolymer, and combinations thereof; and
wherein the fiber has an average length in the range from about 0.2 to about 30 mm; and
wherein the fiber is present in the range from about 30 wt. % to about 60 wt. % based on a total weight of the thermoplastic resin and the fiber;
frothing the mixture to create a froth, and
removing at least a portion of the water in the froth to create a foam,
wherein the foam generated has a non-cellular fibrillated morphology.
2. The method of claim 1 , further comprising:
coating at least a portion of a substrate with a layer of the froth; and
removing a majority of the water from the froth.
3. The method of claim 1 , wherein the removing at least a portion of the water in the froth to create a foam results in a foam having from 0 to 20 weight percent residual water.
4. The method of claim 1 , wherein the dispersion stabilizing agent comprises a fatty acid.
5. The method of claim 1 , wherein the froth stabilizing surfactant comprises cellulose.
6. The method of claim 1 , wherein the dispersion comprises from about 25 to about 74% thermoplastic resin and dispersion stabilizing agent by volume of the dispersion.
7. The method of claim 1 , wherein the dispersion comprises from about 40 to about 55 percent thermoplastic resin and dispersion stabilizing agent by weight, exclusive of any filler.
8. The method of claim 6 , wherein the thermoplastic resin comprises a polyolefin.
9. The method of claim 1 , wherein the fibers have a melting point greater than the thermoplastic resin.
10. The method of claim 1 , wherein the foam has at least one layer having an average thickness of from about 0.01 cm to about 2.5 cm.
11. The method of claim 1 , wherein the fiber has an average length in the range from about 0.5 to about 20 mm.
12. A method for generating a thermoplastic non-cellular fibrillated foam, the method comprising:
melting a thermoplastic resin and a dispersion stabilizing agent in a first part of an extruder to form a polymer melt in a second part of the extruder;
adding water to the polymer melt to form an aqueous dispersion;
adjusting the pH of the aqueous dispersion to between 8 and 11;
adding at least one froth stabilizing surfactant to the aqueous dispersion to form a mixture;
adding fiber to the mixture,
wherein the fiber comprises at least one of a polyethylene homopolymer, copolymer, or multiblock interpolymer, a polypropylene homopolymer, copolymer, or multiblock interpolymer, and combinations thereof; and
wherein the fiber has an average length in the range from about 0.2 to about 30 mm; and
wherein the fiber is present in the range from about 30 wt. % to about 60 wt. % based on a total weight of the thermoplastic resin and the fiber;
frothing the mixture to create a froth; and
removing at least a portion of the water in the froth to create a foam;
wherein the foam created comprises 20 weight percent or less residual water; and
wherein the foam generated has a non-cellular fibrillated morphology.
13. The method of claim 12 , wherein the dispersion stabilizing agent comprises a fatty acid.
14. The method of claim 12 , wherein the froth stabilizing surfactant comprises cellulose.
15. The method of claim 12 , further comprising coating at least a portion of a substrate with a layer of froth.
16. The method of claim 12 , wherein the dispersion comprises from about 25 to about 74% thermoplastic resin and dispersion stabilizing agent by volume of the dispersion.
17. The method of claim 12 , wherein the thermoplastic resin comprises a polyolefin.
18. The method of claim 12 , wherein the fibers have a melting point greater than the thermoplastic resin.
19. The method of claim 12 , wherein the foam has at least one layer having an average thickness of from about 0.01 cm to about 2.5 cm.
20. The method of claim 12 , wherein the resulting foam comprises from 0 to 10 weight percent residual water.
21. The method of claim 12 , wherein the resulting foam comprises from 0 to 8 weight percent residual water.
22. The method of claim 12 , wherein the dispersion comprises from about 40 to about 55 percent thermoplastic resin and dispersion stabilizing agent by weight, exclusive of any filler.
23. The method of claim 12 , wherein the fiber has an average length in the range from about 1 to about 10 mm.