Renewable polyester fibers having a low density

Patent metadata

Field	Value
Publication number	US-12139822-B2
Application number	US-202017111638-A
Country	US
Kind code	B2
Filing date	Dec 4, 2020
Priority date	Feb 10, 2012
Publication date	Nov 12, 2024
Grant date	Nov 12, 2024

Abstract

Fibers that are formed from a thermoplastic composition that contains a rigid renewable polyester and has a voided structure and low density are provided. To achieve such a structure, the renewable polyester is blended with a polymeric toughening additive in which the toughening additive can be dispersed as discrete physical domains within a continuous matrix of the renewable polyester. Fibers are thereafter formed and then stretched or drawn at a temperature below the glass transition temperature of the polyester (i.e., “cold drawn”).

First claim

What is claimed is:

1. A method for forming a low density fiber, the method comprising:
forming a blend that contains a polyester and a polymeric toughening additive, wherein the polyester has a glass transition temperature of about 0° C. or more, wherein the fiber contains domains of the polymeric toughening additive with an axial dimension ranging from about 0.05 μm to about 30 μm;
extruding the blend through a die to form the fiber; and
drawing the fiber at a temperature that is lower than the glass transition temperature of the polyester to form a thermoplastic composition that contains a plurality of voids and has a density of about 1.4 grams per cubic centimeter or less, wherein the axial dimension of the voids is about 5 micrometers or less.

2. The method of claim 1 , further comprising annealing the drawn fiber at a temperature that is above the glass transition temperature of the polyester.

3. The method of claim 1 , wherein the fiber has a density of from about 0.5 grams per cubic centimeter to about 0.95 grams per cubic centimeter.

4. The method of claim 1 , wherein the average percent volume of the fiber that is occupied by the voids is from about 20% to about 80% per cubic centimeter.

5. The method of claim 1 , wherein the polyester is a polylactic acid.

6. The method of claim 1 , wherein the polymeric toughening additive includes a propylene homopolymer, propylene/α-olefin copolymer, ethylene/α-olefin copolymer, or a combination thereof.

7. The method of claim 1 , wherein the blend comprises at least one interphase modifier.

8. The method of claim 1 , wherein the blend further comprises a polyepoxide modifier that includes an epoxy-functional (meth)acrylic monomeric component.

9. The method of claim 1 , wherein the fiber is drawn to a stretch ratio of from about 1.1 to about 3.0.

10. The method of claim 1 , wherein the fiber is drawn at a temperature at least about 10° C. below the glass transition temperature of the polyester.

11. The method of claim 1 , wherein the blend is generally free of gaseous blowing agents.

Assignees

• Kimberly Clark Co

Inventors

• Mceneany Ryan J
• Topolkaraev Vasily A
• Scholl Neil T
• Eby Thomas A

Classifications

• B29C48/911

  Cooling · CPC title

• B29C2948/92704

  Temperature · CPC title

• B29C48/022

  characterised by the choice of material · CPC title

• B29C48/04

  Particle-shaped (making granules B29B9/00) · CPC title

• B29C48/05

  Filamentary, e.g. strands · CPC title