# US 8,569,408 B2 · Acrylonitrile copolymer and method for producing the same, acrylonitrile copolymer solution and polyacrylonitrile precursor fiber for carbon fiber and method for producing the same

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- Number: US 8,569,408 B2
- Document ID: US8569408B2
- Status: Granted
- Kind: B2
- Application number: 12/994,526
- Filed: 2009-05-12
- Published: 2011-06-02
- Granted: 2013-10-29
- Earliest claimed: 2008-05-30
- Assignees: Mitsubishi Rayon Co., Ltd.
- Applicants: Norifumi Hirota; Yusuke Shinmen; Naomasa Matsuyama; Takeshi Nii; Harumi Shibatani
- Inventors: Norifumi Hirota; Yusuke Shinmen; Naomasa Matsuyama; Takeshi Nii; Harumi Shibatani
- Web page: https://patentgrep.com/patent/US8569408B2

## CPC

- C08F 4/40: Redox systems
- C08F 220/44: Acrylonitrile
- D01F 6/38: comprising unsaturated nitriles as the major constituent
- D01F 9/22: from polyacrylonitriles
- C08F 220/06: Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
- C08F 220/56: Acrylamide; Methacrylamide
- C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- D01F: CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS

## Abstract

Disclosed are an acrylonitrile copolymer excellent in thermal stability as a solution (spinning dope) when dissolved in an amide solvent and capable of forming dense polyacrylonitrile fiber suitable for production of carbon fiber, an acrylonitrile copolymer solution in which the acrylonitrile copolymer is dissolved in an amide solvent, and a method for producing polyacrylonitrile precursor fiber for carbon fiber by use of the acrylonitrile copolymer solution. Specifically, an acrylonitrile copolymer contains a sulfonate group derived from a polymerization initiator in an amount of 1.0×10−5 equivalent/g or more, and the value (equivalent ratio) of (the content of a sulfate group derived from the polymerization initiator/the total content of the sulfonate group and the sulfate group) is 0.4 or less; an acrylonitrile copolymer solution contains the aforementioned acrylonitrile copolymer and an amide solvent.

## Claims

### Claim 1

An acrylonitrile copolymer comprising a sulfonate group derived from a polymerization initiator in an amount of 1.0×10−5 equivalent/g or more, an equivalent ratio of a content of a sulfate group derived from the polymerization initiator/a total content of the sulfonate group and the sulfate group being 0.4 or less,
wherein a total content of the sulfonate group and/or the sulfate group in the acrylonitrile copolymer is 1.0×10−5 equivalent/g or more and less than 4.0×10−5 equivalent/g.

### Claim 2 (depends on 1)

A method for producing the acrylonitrile copolymer according to claim 1, comprising
copolymerizing acrylonitrile with a vinyl monomer in the presence of at least one polymerization initiator selected from the group consisting of a persulfate and a sulfite.

### Claim 3 (depends on 1)

A method for producing the acrylonitrile copolymer according to claim 1,
comprising copolymerizing acrylonitrile with a vinyl monomer in the presence of at least one polymerization initiator selected from the group consisting of a persulfate and a sulfite to form a copolymer, then hydrolyzing a sulfate group in the copolymer.

### Claim 4 (depends on 3)

The method for producing the acrylonitrile copolymer according to claim 3, wherein hydrolysis of the sulfate group in said copolymer is carried out in a solution comprising said copolymer and an amide solvent.

### Claim 5 (depends on 1)

An acrylonitrile copolymer solution comprising the acrylonitrile copolymer according to claim 1 and an amide solvent.

### Claim 6 (depends on 5)

The acrylonitrile copolymer solution according to claim 5, wherein the amide solvent is at least one of dimethylacetamide and dimethylformamide.

### Claim 7 (depends on 5, 6)

A method for producing polyacrylonitrile precursor fiber for carbon fiber comprising the step of spinning the acrylonitrile copolymer solution according to claim 5 or 6 as spinning dope.

### Claim 8 (depends on 1)

Acrylonitrile precursor fiber for carbon fiber to be obtained from coagulated fiber obtained by spinning of an acrylonitrile copolymer solution as spinning dope, an acrylonitrile copolymer in said precursor fiber being the acrylonitrile copolymer according to claim 1.