# US 4,400,339 A · Process for producing very fine denier synthetic fibers

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- Number: US 4,400,339 A
- Document ID: US4400339A
- Status: Granted
- Kind: A
- Application number: 06/213,531
- Filed: 1980-12-04
- Granted: 1983-08-23
- Earliest claimed: 1979-12-21
- Assignees: Bayer Aktiengesellschaft
- Inventors: Ulrich Reinehr; Toni Herbertz; Hermann J. Jungverdorben; Joachim Dross
- Web page: https://patentgrep.com/patent/US4400339A

## CPC

- D01D 5/098: with simultaneous stretching
- D01D 5/04: Dry spinning methods {(D01D5/0038 takes precedence)}
- D01F 6/18: from polymers of unsaturated nitriles, e.g. polyacrylonitrile, polyvinylidene cyanide
- Y10T 428/2913: Rod, strand, filament or fiber
- Y10T 428/2973: Particular cross section
- Y10T 428/2978: Surface characteristic
- D01D: MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01F: CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

Dry-spun synthetic fibers and filaments having an individual as-spun denier of 3 dtex are obtained by dry-spinning a viscosity-stable spinning solution with a draft of at least 20.

## Claims

### Claim 1

A process for the production of synthetic acrylonitrile fibers and filaments having at least 40% by weight acrylonitrile units and individual as spun deniers of 3 dtex and less from filament-forming synthetic polyacrylonitrile polymers containing at least 40% by weight acrylonitrile units by a dry spinning process and further treating the spun material in a manner known per se to produce finished fibers or filaments, comprising spinning a viscosity-stable spinning solution in an organic solvent under thermal conditions such that a draft of at least 30 is established.

### Claim 2 (depends on 1)

A process according to claim 1, in which dimethyl formamide is used as the spinning solvent.

### Claim 3 (depends on 1)

A process according to claim 1, in which the spinning solution is spun with a draft of from 30 to 500.

### Claim 4 (depends on 1)

A process according to claim 1, in which filaments are produced having round to bean-shaped cross sections.

### Claim 5 (depends on 1)

A process according to claim 1, wherein said viscosity stable spinning solution contains a polar organic solvent.

### Claim 6 (depends on 5)

A process according to claim 5, wherein said polar organic solvent is selected from the group consisting of dimethyl acetamide, dimethyl sulphoxide, ethylene carbonate and N-methyl pyrrolidone.