# US 4,393,093 A · Preparation of high gamma (.alpha.)phase poly(vinylidene fluoride) piezoelectric materials

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

- Number: US 4,393,093 A
- Document ID: US4393093A
- Status: Granted
- Kind: A
- Application number: 06/272,823
- Filed: 1981-06-12
- Granted: 1983-07-12
- Earliest claimed: 1981-06-12
- Assignees: Pennwalt Corporation
- Inventors: Oliver S. Sprout, Jr.
- Web page: https://patentgrep.com/patent/US4393093A

## CPC

- H10N 30/098: Forming organic materials
- B29C 59/14: by plasma treatment {(plasma tubes per se H01J)}
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)

## Abstract

The piezoelectric and pyroelectric activity of vinylidene fluoride polymers is enhanced by treating the polymers with a glow discharge at a reduced pressure. The treatment is believed to convert a portion of the .alpha. phase crystal content of the polymers to the .gamma. phase. Piezoelectric and pyroelectric elements are formed by metallizing a film of the treated polymer and poling the metallized film.

## Claims

### Claim 1

A process for increasing the piezoelectric activity of a vinylidene fluoride polymer containing an .alpha. crystalline phase and having an .alpha./.beta. ratio of at least about 0.05 comprising treating the polymer with a glow discharge at reduced pressure to convert a portion of the .alpha. crystalline phase to .gamma. crystalline phase and then poling the polymer in an electric field.

### Claim 2 (depends on 1)

The process of claim 1 including the step of coating the polymer with a metal film.

### Claim 3 (depends on 2)

The process of claim 2 wherein the treating and coating is carried out in the same vacuum chamber.

### Claim 4 (depends on 1)

The process of claim 1 wherein the polymer is treated at a pressure of 0.01 to 2 torr for from at least about 3 minutes.

### Claim 5 (depends on 1)

The process of claim 1 wherein the polymer is in the form of a film and, after the polymer is treated with the glow discharge, it is coated on each side with a metal film so as to form a piezoelectric element.

### Claim 6 (depends on 1)

The process of claim 1 wherein the polymer is a poly(vinylidene fluoride) homopolymer.

### Claim 7 (depends on 1)

The process of claim 1 wherein the the .alpha./.beta. ratio is from about 0.05 to 3.0.