# US 5,346,926 A · Small diameter electric wire insulated with highly expanded cellular polyethylene and production thereof

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- Number: US 5,346,926 A
- Document ID: US5346926A
- Status: Granted
- Kind: A
- Application number: 08/136,667
- Filed: 1993-10-14
- Granted: 1994-09-13
- Earliest claimed: 1993-10-14
- Assignees: Nippon Unicar Company Limited
- Inventors: Toshio Sakamoto; Kenichiro Kumai; Shigeru Gotoh
- Web page: https://patentgrep.com/patent/US5346926A

## CPC

- C08J 9/10: developing nitrogen {, the blowing agent being a compound containing a nitrogen-to-nitrogen bond}
- C08L 23/06: Polyethylene
- C08L 23/0815: {with aliphatic 1-olefins containing one carbon-to-carbon double bond}
- H01B 3/441: {from alkenes}
- C08J 2323/06: Polyethene
- C08L 91/06: Waxes
- C08L 2203/202: use in electrical wires or wirecoating
- C08L 2205/02: containing two or more polymers of the same C08L -group
- C08L 2205/03: containing three or more polymers in a blend
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- H01B: CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES (selection for magnetic properties H01F1/00; waveguides H01P {; printed circuits H05K})

## Abstract

A process for producing an expandable resin composition for a small diameter electric wire insulated with highly expanded cellular polyethylene which comprises (1) heat-kneading at a temperature higher than 135.degree. C. a mixture comprising: (i) a low density polyethylene having a density ranging from about 0.890 to 0.925 g/ml; (ii) a high density polyethylene having a melting point higher than 130.degree. C.; and (iii) a polyolefin wax having an average molecular weight ranging from about 1500 to 8000 and a melting point ranging from about 100.degree. C. to 160.degree. C.; and (2) heat kneading at a temperature ranging from 120.degree. C. to 130.degree. C. and at a preliminary expansion ratio lower than 5% the mixture of step (1) with a low temperature decomposable chemical blowing agent.

## Claims

### Claim 1

A process for producing an expandable resin composition for a small diameter electric wire insulated with a highly-expanded cellular polyethylene, said process comprising:
(1) heat-kneading at a temperature higher than 135.degree. C.
(i) 100 parts by weight of a low density polyethylene having a density of 0.890 to 0.925 g/ml;
(ii) 1 to 110 parts by weight of a high-density polyethylene having a melting point higher than 130.degree. C.; and
(iii) 0.3 to 5 parts by weight of a low molecular weight polyolefin wax having an average molecular weight 1500 to 8000 and a melting point of 100.degree. C. to 160.degree. C.; and
(2) heat-kneading at a temperature of 120.degree. C. to 130.degree. C. and at preliminary expansion ratio lower than 5%:
(i) 100 parts by weight of the mixture obtained in (1) with;
(ii) 0.5 to 5 parts by weight of a low temperature decomposable chemical blowing agent.

### Claim 2 (depends on 1)

A process for producing an expandable resin composition according to claim 1, wherein a low molecular weight polyolefin wax is a low molecular weight polyethylene wax or a low molecular weight polypropylene wax.

### Claim 3 (depends on 2)

A process for producing an expandable resin composition according to claim 2, wherein a low temperature decomposable chemical blowing agent is a p,p'-oxybisbenzenesulfonylhydrazide and azo-dicarbonamide treated with a blowing auxiliary in a mixing ratio of 1:1 to 2:1.

### Claim 4 (depends on 1)

An expandable resin composition for highly-expanded insulating polyethylene prepared according to claim 1.

### Claim 5 (depends on 4)

A production method for a small diameter electric wire insulated with highly-expanded cellular polyethylene characterized by extrusion covering a wire with an expandable resin composition as according to claim 4 at a temperature 130.degree. C. to 160.degree. C.

### Claim 6 (depends on 5)

A small diameter electric wire insulated with highly expanded cellular polyethylene produced by the method of claim 5.

### Claim 7

A composition comprising:
(A) 100 parts by weight of a mixture comprising;
(i) 100 parts by weight of a low density polyethylene having a density of 0.890 to 0.925 g/ml,
(ii) 1 to 110 parts by weight of a high-density polyethylene having a melting point higher than 130.degree. C.; and
(iii) 0.3 to 5 parts by weight of a low molecular weight polyolefin wax having an average molecular weight of 1500 to 8000 and a melting point of 100.degree. C. to 160.degree. C.; and
(B) 0.5 to 5 parts by weight of a low temperature decomposable chemical blowing agent.