US3931446A
Expired / Lapsed
US
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Process for producing polymeric piezoelectric elements and the article formed thereby
Assignee: Kureha Corp
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Filing: 1974-03-11
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Granted: 1976-01-06
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Expires: 1994-03-11
Abstract
Abstract A highly piezoelectric polyvinylidene fluoride element is prepared by treating a polyvinylidene fluoride film having an infrared absorbance ratio D 530 /D 510 of not more than 1.2, namely having a major proportion of β-type crystal structure, at a temperature of at least 40°C but below the melting point of the film while applying to the film a direct current voltage of 200 KV/cm to 1,500 KV/cm. The polyvinylidene fluoride film having a major proportion of β-type crystal structure may be obtained by stretching a fabricated article of polyvinylidene fluoride having a major proportion of α-type crystal structure under specific conditions.
Inventors
- 👤 Naohiro Murayama
- 👤 Takao Oikawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 13:47
CPC Classifications
C; C08; C08J; C08J5/00; C08J5/18; B; B29; B29C; B29C71/00; B29C71/0063; H; H01; H01G; H01G7/00; H01G7/02; H01G7/021; H01G7/023; H10; H10N; H10N30/00; H10N30/01; H10N30/09; H10N30/098; C08J2327/00; C08J2327/02; C08J2327/12; C08J2327/16; Y; Y10; Y10T; Y10T428/00; Y10T428/31504; Y10T428/3154; Y10T428/31678
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
33 words
A polarized piezoelectric film comprising an oriented or unoriented polyvinylidene fluoride having electrodes on both surfaces, wherein said PVDF has an infrared absorbance ratio D 530 /D.sub. 510 of not more than 1.2.
Claim 2
Dependent Claim
33 words
A polarized piezoelectric film comprising an oriented or unoriented polyvinylidene fluoride having electrodes on both surfaces, wherein said PVDF has an infrared absorbance ratio D 530 /D.sub. 510 of not more than 1.2.
Claim 3
Dependent Claim
22 words
The film of claim 1, wherein said PVDF has an infrared absorbance ratio D 530 /D 510 of not more than 0.6.
Claim 4
Dependent Claim
15 words
The film of claim 1, wherein said electrodes are formed by a vacuum metallizing process.
Claim 5
Dependent Claim
20 words
The film of claim 1, wherein said film has a piezoelectric constant in excess of 1.5 × 10.sup. -7 c.g.s.e.s.u.
Claim 6
Dependent Claim
116 words
A process for producing highly piezoelectric elements which comprises stretching a polyvinylidene fluoride film having a major proportion of the α-type crystal structure at a temperature not higher than 100°C in at least one axial direction to form a polyvinylidene fluoride film having a major proportion of the β-type crystal structure as exibited by an infrared absorbance ratio D 530 /D.sub. 510 of not more than 1.2; attaching electrodes on both surfaces of the resulting film; and then treating the resulting film with the electrodes to a temperature of at least 40°C, but below the melting point of said film, while applying to said film a direct current voltage of between 200 KV/cm amd 1,500 KV/cm.
Claim 7
Dependent Claim
116 words
A process for producing highly piezoelectric elements which comprises stretching a polyvinylidene fluoride film having a major proportion of the α-type crystal structure at a temperature not higher than 100°C in at least one axial direction to form a polyvinylidene fluoride film having a major proportion of the β-type crystal structure as exibited by an infrared absorbance ratio D 530 /D.sub. 510 of not more than 1.2; attaching electrodes on both surfaces of the resulting film; and then treating the resulting film with the electrodes to a temperature of at least 40°C, but below the melting point of said film, while applying to said film a direct current voltage of between 200 KV/cm amd 1,500 KV/cm.
Claim 8
Dependent Claim
17 words
The process of claim 1, wherein said film is heated at a temperature of 50°C to 160°C.
Claim 9
Dependent Claim
41 words
The process of claim 1, wherein prior to said heating, said film having a major proportion of the β-type crystal structure is heat-treated under tension at a temperature of at least 80° C but below the melting point of said film.
Claim 10
Dependent Claim
19 words
The process of claim 1, wherein said film is heated for a period of 10 minutes to 2 hours.
Claim 11
Dependent Claim
15 words
The process of claim 1, wherein said electrodes are formed by a vacuum metallizing process.
Claim 12
Dependent Claim
12 words
The process of claim 1, wherein said stretching is conducted below 100°C.
Claim 13
Dependent Claim
31 words
The process of claim 1, wherein said film having a major part of the β-type crystal structure exibits an infrared absorbance ratio D 530 /D 510 of not more than 0.6.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-01-05 | 1979-07-07 | 1980-01-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-01-05 | 1983-07-07 | 1984-01-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-01-05 | 1987-07-07 | 1988-01-06 | $7700.00 | Window Closed / Lapsed |