# US 6,720,379 B1 · Electrostatic dissipative plastics adapted particularly for use at elevated temperatures

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 6,720,379 B1
- Document ID: US6720379B1
- Status: Granted
- Kind: B1
- Application number: 09/448,666
- Filed: 1999-11-24
- Granted: 2004-04-13
- Earliest claimed: 1998-11-24
- Inventors: Richard W. Campbell; Chi Way Lau
- Web page: https://patentgrep.com/patent/US6720379B1

## CPC

- C08K 7/06: Elements
- H01B 1/24: the conductive material comprising carbon-silicon compounds, carbon or silicon
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- 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

Resins suitable for use in compression molding processes are prepared by mixing between about 10 and 30 weight % of chopped partially carbonized fibers, i.e. fibers having a carbon content of between about 70 to 95% by weight and an average size of about 100 μm, with compression grade molding resins. Typically the compression grade molding resins are about 100 μm When chopped carbon fibers of reduced conductivity are used the curve obtained by plotting the resistivity against the concentration of carbon fibers is less steep in the critical regions of interest (i.e., between about 1010 and 1012 and between about 106 and 109) than is the curve obtained when high conductivity fibers are used. It has been observed that even if some dielectric breakdown occurs, the connected fibers are not as conductive and the effect has been found not to be as significant as is the case with the usual carbon fibers which have maximized conductivity.

## Claims

### Claim 1

A compression molding composition comprising a compression molding resin and partially carbonized fibers, wherein said fibers have an average size of about 100 μm and said resin is a particulate compression grade molding resin having an average particle size of about 100 μm.

### Claim 2 (depends on 1)

A compression molding composition according to claim 1, wherein said partially carbonized fibers comprise from about 70% to about 95% by weight of carbon.

### Claim 3 (depends on 1)

A compression molding composition according to claim 1, wherein said partially carbonized fibers are present in the amount from about 10% to about 30% by weight.

### Claim 4 (depends on 1)

A compression molding composition according to claim 1, wherein said resin is a thermoplastic resin.

### Claim 5 (depends on 3)

A compression molding composition according to claim 3, wherein said resin is selected from the group consisting of polyphenylenesulphides, polyamideimides, polyetheretherketones, polytertafluoroethylene, polyetherimides, and polyethersulfones.

### Claim 6 (depends on 1)

A compression molding composition according to claim 1 further comprising glass fibers.

### Claim 7 (depends on 1)

An article of manufacture obtained by compression molding a resin composition according to claim 1, wherein said article has a surface resistivity from about 106 to about 1012 Ω/□.

### Claim 8 (depends on 1)

An article of manufacture obtained by compression molding a resin composition according to claim 1, wherein said article has a surface resistivity from about 1010 to about 1012 Ω/□.

### Claim 9 (depends on 1)

An article of manufacture obtained by compression molding a resin composition according to claim 1, wherein said article has a surface resistivity from about 106 to about 109 Ω/□.

### Claim 10 (depends on 1)

An article of manufacture obtained by compression molding a resin composition according to claim 1, wherein said article has a surface resistivity within about one to about two orders of magnitude and said resistivity is in the range from about 106 to about 1012 Ω/□.

### Claim 11 (depends on 1)

An article of manufacture according to claim 1, wherein said article exhibits stable surface resistivity at a temperature of at least 160° C.

### Claim 12 (depends on 11)

A article according to claim 11, wherein said article has a surface resistivity from about 106 to about 1012 Ω/□.

### Claim 13 (depends on 1)

An article of manufacture obtained by compression molding a resin composition according to claim 1, wherein said article substantially retains its initial surface resistivity after exposure to applied voltage in excess of about 100 volts.

### Claim 14 (depends on 1)

A process for producing a shaped article comprising compression molding a resin composition according to claim 1 into a desired shape.

### Claim 15

A process for producing a compression molding composition comprising mixing partially carbonized fibers having a particle size of about 100 μm and a particulate compression grade molding resin having an average particle size of about 100 μm.