High tenacity low shrinkage polyamide yarns

Patent metadata

Field	Value
Publication number	US-10125436-B2
Application number	US-25950908-A
Country	US
Kind code	B2
Filing date	Oct 28, 2008
Priority date	Nov 9, 2007
Publication date	Nov 13, 2018
Grant date	Nov 13, 2018

Abstract

Multi-filament polyamide yarns characterized by high tenacity and low shrinkage are disclosed. Such yarns or fabrics made therefrom can be used in industrial applications in which such a combination of properties is desirable. Such yarns are particularly useful in the manufacture of automobile airbag fabrics. Also disclosed is a process for making such yarns. The yarn manufacturing process involves spin-drawing molten nylon, relaxing and controlling the yarn tension, and then winding the yarn. Yarns made according to this process exhibit linear density in the range of 110-940 decitex, tenacity equal to or greater than 80 cN/tex, and shrinkage, measured at 177° C., of less than 5%.

First claim

What is claimed is:

1. A spin-draw process for manufacturing a multifilament polyamide yarn having a tenacity equal to or greater than 80 cN/tex, a hot air shrinkage at 177° C. of less than 5% measured according to ASTM D4974 and linear density less than 940 decitex comprising the steps:
a. extruding molten nylon at a formic acid relative viscosity from about 40-85 through a multi-capillary spinneret into a plurality of filaments which are then directed through a quench zone;
b. coalescing the filaments into a multifilament yarn and applying lubricating spin finish to said
c. directing the yarn, by means of at least one feed roll, to a draw zone consisting of at least two pair of driven draw rolls, each roll within a pair rotating at the same peripheral speed, and each pair rotating at a relatively higher peripheral speed than the pair preceding it;
d. causing the yarn to form at least two wraps around each said pair of draw rolls;
e. maintaining the yarn at a temperature of 160°-245° C. as it passes over the at least two pairs of draw rolls by heating the immediate zone surrounding the said pairs of rolls with hot, dry air or by heating the rolls, or by a combination of both;
f. controlling the relative peripheral speeds of the rolls between each pair of draw rolls and the following pair of draw rolls, and controlling the temperature of the yarn as it passes over the at least two pairs of draw rolls, so as to impart an increasing extent of draw to the yarn as it traverses each pair of draw rolls and finally achieves a total yarn draw ratio of 4.2-5.8;
g. directing the yarn to a tension relaxation and control zone consisting of a first driven tension relaxation roll and a second driven tension control roll wherein said first roll is rotating at a lower peripheral speed relative to the final pair of draw rolls that the yarn just exited, thereby achieving a relaxation ratio of about 12 to about 13%, and rotating at a lower rate than said second roll, such that the ratio of peripheral speeds of the second to the first roll in the tension relaxation and control zone is about 1.01 to about 1.07, and so as to maintain a stable yarn tension in the tension relaxation and control zone that is higher than that experienced by the yarn as it exits the draw zone, wherein the draw zone is at a temperature of 210° C.;
h. directing the yarn through an interlacing jet; and
i. directing the yarn to a wind-up roll rotating at a relatively higher peripheral speed than the second roll of the tension relaxation and control zone so as to maintain a stable yarn tension during wind-up, and such that the yarn traversing the tension relaxation and control zone is at a higher tension than the yarn exiting the last pair of draw rolls and at a lower tension than that of the yarn as it is wound on the wind-up roll.

2. A woven or knit fabric comprising a yarn produced in accordance with the process of claim 1 .

3. An article of manufacture made from the fabric of claim 2 .

4. An uncoated woven fabric of claim 2 characterized by an air permeability of less than 1001/dm 2 /min at 500 Pa.

5. An uncoated woven fabric according to claim 2 characterized by an air permeability in the range 1 to 30 l/dm 2 /min.

6. An uncoated woven fabric according to claim 2 characterized by an air permeability in the range of 1 to 10 l/dm 2 /min.

7. An airbag comprising the fabric of claim 6 .

8. A one piece, woven airbag comprising the fabric of claim 6 .

9. A fabric according to claim 2 further comprising a coating wherein the coating is applied at a loading in the range of 5 to 130 g/m 2 and wherein said coating comprises a polymer selected from the group consisting of silicones, polyurethanes, and mixtures and reaction products thereof.

10. A coated fabric according to claim 9 characterized by an air permeability of less than 2 l/dm 2 /min.

11. An airbag comprising the fabric of claim 10 .

12. A one piece, woven airbag comprising the fabric of claim 10 .

13. A fabric according to claim 2 further comprising a laminated structure of fabric and film wherein the film has a density in the range of 5 to 130 g/m 2 and wherein said film comprises a polymer selected from the group consisting of silicones, polyurethanes, and mixtures and reaction products thereof.

14. A fabric which comprises a multifilament yarn produced in accordance with the process of claim 1 oriented parallel to the weft direction.

15. A fabric which comprises a multifilament yarn produced in accordance with the process of claim 1 oriented parallel to the warp direction.

Assignees

• Barnes John Alan
• Dempster David Forbes
• Invista North America Sarl

Inventors

• Barnes John Alan
• Dempster David Forbes

Classifications

• D01D10/02

  Heat treatment (heating for finishing D02J13/00) · CPC title

• D01F6/605

  from aromatic polyamides · CPC title

• Y10T442/3976

  Including strand which is stated to have specific attributes [e.g., heat or fire resistance, chemical or solvent resistance, high absorption for aqueous composition, water solubility, heat shrinkability, etc.] · CPC title

• Y10T442/2139

  Coating or impregnation specified as porous or permeable to a specific substance [e.g., water vapor, air, etc.] · CPC title

• D02G3/446

  Yarns or threads for use in automotive applications · CPC title