# US 4,399,061 A · Preparation of video disc molding composition

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- Number: US 4,399,061 A
- Document ID: US4399061A
- Status: Granted
- Kind: A
- Application number: 06/311,165
- Filed: 1981-10-14
- Granted: 1983-08-16
- Earliest claimed: 1981-10-14
- Assignees: RCA Corporation
- Inventors: Paulo Sickert
- Web page: https://patentgrep.com/patent/US4399061A

## CPC

- H01B 1/24: the conductive material comprising carbon-silicon compounds, carbon or silicon
- C08J 3/203: {Solid polymers with solid and/or liquid additives}
- C08J 2327/06: Homopolymers or copolymers of vinyl chloride
- 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})
- 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)

## Abstract

An improvement in preparing PVC resin based conductive molding compositions suitable for the manufacture of capacitive high density information discs wherein isopropyl alcohol is added to ingredients to be dry blended thus substantially reducing the amount of powder which accumulates on the inner surface of the mixing vessel during blending.

## Claims

### Claim 1

In a process for preparing a conductive vinyl chloride resin based molding composition containing at least about 12 percent by weight of conductive carbon black particles wherein certain components of said composition, including said resin and carbon black, are mixed in the dry state in a mixing vessel, said mixing having the tendency to deposit powder onto the inner surface of said vessel, the improvement comprising adding to said dry components an amount of isopropyl alcohol sufficient to substantially reduce the amount of powder deposited on said surface during mixing, but not exceeding about 2 percent by weight of said composition.

### Claim 2 (depends on 1)

A process in accordance with claim 1, wherein the amount of isopropyl alcohol added comprises from about 0.5 to about 1.5 percent by weight of said conductive molding composition.

### Claim 3 (depends on 1)

A process in accordance with claim 1, wherein the amount of isopropyl alcohol added comprises about 1 percent by weight of said conductive molding composition.