# US 7,744,999 B2 · Crystallized meta-aramid blends for improved flash fire and arc protection

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- Number: US 7,744,999 B2
- Document ID: US7744999B2
- Status: Granted
- Kind: B2
- Application number: 12/218,125
- Filed: 2008-07-11
- Published: 2010-01-14
- Granted: 2010-06-29
- Earliest claimed: 2008-07-11
- Assignees: E. I. Du Pont de Nemours and Company
- Inventors: Reiyao Zhu
- Web page: https://patentgrep.com/patent/US7744999B2

## CPC

- D02G 3/443: {Heat-resistant, fireproof or flame-retardant yarns or threads (fire- or flame-proof filaments D01F1/07; woven fabrics using heat-resistant or fireproof threads D03D15/513)}
- D02G 3/047: {including aramid fibres}
- D10B 2321/101: modacrylic
- D10B 2331/021: aromatic polyamides, e.g. aramides
- Y10T 428/2915: including textile, cloth or fabric
- Y10T 428/2969: Polyamide, polyimide or polyester
- Y10T 442/3976: 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.]
- Y10T 442/3984: Strand is other than glass and is heat or fire resistant
- D02G: CRIMPING OR CURLING FIBRES, FILAMENTS, THREADS, OR YARNS; YARNS OR THREADS
- D10B: INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A yarn, fabric, and garment suitable for use in arc and flame protection and having improved flash fire protection contains a majority, by weight, of meta-aramid fibers having a degree of crystallinity of at least 20%, and a minority of modacrylic fibers, para-aramid fibers, and antistatic fibers. Garments made from the yarns provide thermal protection such that a wearer would experience less than a 65 percent predicted body burn when exposed to a flash fire exposure of 4 seconds per ASTM F1930, while maintaining a Category 2 arc rating per ASTM F1959 and NFPA 70E.

## Claims

### Claim 1

A yarn for use in arc and flame protection consisting essentially of:
(a) 50 to 80 weight percent meta-aramid fiber having a degree of crystallinity of at least 20%;
(b) 10 to 30 weight percent modacrylic fiber;
(c) 5 to 20 weight percent para-aramid fiber; and
(d) 1 to 3 weight percent antistatic fiber;
said percentages on the basis of components (a), (b), (c), and (d).

### Claim 2 (depends on 1)

The yarn of claim 1 consisting essentially of:
(a) 65 to 75 weight percent meta-aramid fiber;
(b) 15 to 25 weight percent modacrylic fiber;
(c) 5 to 15 weight percent para-aramid fiber; and
(d) 2 to 3 weight percent antistatic fiber.

### Claim 3 (depends on 1)

The yarn of claim 1 wherein the anti-static component comprises carbon or metal.

### Claim 4 (depends on 1)

The yarn of claim 1 with the meta-aramid fiber has a degree of crystallinity in a range from 20 to 50%.

### Claim 5

A fabric suitable for use in arc and flame protection comprising a yarn consisting essentially of:
(a) 50 to 80 weight percent meta-aramid fiber having a degree of crystallinity of at least 20%;
(b) 10 to 30 weight percent modacrylic fiber;
(c) 5 to 20 weight percent para-aramid fiber; and
(d) 1 to 3 weight percent antistatic fiber;
said percentages on the basis of components (a), (b), (c), and (d);
the fabric having a basis weight in the range of 186.5 to 237 grams per square meter (5.5 to 7 ounces per square yard).

### Claim 6 (depends on 5)

The fabric of claim 5 wherein the yarn consists essentially of:
(a) 65 to 75 weight percent meta-aramid fiber;
(b) 15 to 25 weight percent modacrylic fiber;
(c) 5 to 15 weight percent para-aramid fiber; and
(d) 2 to 3 weight percent antistatic fiber.

### Claim 7 (depends on 5)

The fabric of claim 5 having a char length according to ASTM D-6413-99 of less than 6 inches.

### Claim 8 (depends on 5)

The fabric of claim 5 having arc resistance according to ASTM F-1959-99 of at least 1.1 calories per square centimeter per ounce per square yard of fabric.

### Claim 9 (depends on 8)

The fabric of claim 8 wherein the arc resistance is at least 1.3 calories per square centimeter per ounce per square yard of fabric.

### Claim 10 (depends on 5)

The fabric of claim 5 wherein the meta-aramid fiber has a degree of crystallinity in a range from 20 to 50%.

### Claim 11 (depends on 5)

The fabric of claim 5 having a shrinkage of 5% or less after 10 wash cycles.

### Claim 12

A garment suitable for use in arc and flame protection comprising a fabric consisting essentially of:
(a) 50 to 80 weight percent meta-aramid fiber having a degree of crystallinity of at least 20%;
(b) 10 to 30 weight percent modacrylic fiber;
(c) 5 to 20 weight percent para-aramid fiber; and
(d) 1 to 3 weight percent antistatic fiber;
said percentages on the basis of components (a), (b), (c), and (d)
the fabrics having a basis weight in the range of 186.5 to 237 grams per square meter (5.5 to 7 ounces per square yard).

### Claim 13 (depends on 12)

The garment of claim 12 wherein the fabric consists essentially of:
(a) 65 to 75 weight percent meta-aramid fiber;
(b) 15 to 25 weight percent modacrylic fiber;
(c) 5 to 15 weight percent para-aramid fiber; and
(d) 2 to 3 weight percent antistatic fiber.

### Claim 14 (depends on 12)

The garment of claim 12, providing thermal protection equivalent to less than a 65% body burn at a 4 sec flame exposure per ASTM F1930, while maintaining a Category 2 arc rating per ASTM F1959 and NFPA 70E.

### Claim 15 (depends on 12)

The garment of claim 12 wherein the fabric has a shrinkage of 5% or less after 10 wash cycles.