Claims
- 1. A dielectric film comprising vinylidene fluoride polymer comprising at least about 70 mole percent vinylidene fluoride monomer units;
- said polymer having crystalline regions comprising in major proportion alpha-form crystal structure;
- said crystalline regions having a degree of orientation, .pi., of the molecular axes in the direction substantially parallel to the film surface of from about 0.8 to about 1.0;
- said vinylidene fluoride polymer having an inherent viscosity of from about 0.8 to about 1.8 dl/g as a solution thereof in dimethylformamide at a concentration of 0.4 g/dl at 30.degree. C.;
- said film exhibiting substantially no heat shrinkage when heated from room temperature to a temperature just below the melting point of the polymer.
- 2. The dielectric film of claim 1, wherein said vinylidene fluoride polymer comprises at least about 75 mol% of vinylidene fluoride monomer units.
- 3. The dielectric film of claim 1, wherein said vinylidene fluoride polymer comprises at least about 80 mol% of vinylidene fluoride monomer units.
- 4. The dielectric film of anyone of claim 1, 2, or 3, wherein said vinylidene fluoride polymer has an inherent viscosity of from about 1.0 to about 1.4.
- 5. The dielectric film of anyone of claim 1, 2, or 3 wherein said film consists essentially of vinylidene fluoride polymer.
- 6. The dielectric film of claim 1, in which the composition of the crystal structure has an absorption ratio D.sub.530 /D.sub.510 of greater than about 3.
- 7. The dielectric film of anyone of claim 1, 2, or 3 wherein the molecular axes in crystal regions of the film are anisotropically oriented within the plane of the film and the dichroic ratio, D-perpendicular/D-parallel in the characteristic infrared absorption at 530 cm.sup.-1 of the predominant crystal form is greater than 1.0.
- 8. The dielectric film of anyone of claim 1, 2, or 3 wherein the dichroic ratio, D-perpendicular/D-parallel, in the characteristic infrared absorption at 530 cm.sup.-1 of the predominant crystal form is greater than 1.3.
- 9. The dielectric film of anyone of claim 1, 2, or 3 wherein the dielectric constant is greater than 11 at a temperature of 20.degree. C. and at a frequency of 1 KHz and its variation between 20.degree. to 80.degree. C. is within .+-.5% of the half value of the sum of a dielectric constant measured at 20.degree. C. and that measured at 80.degree. C., at 1 KHz.
Priority Claims (1)
Number |
Date |
Country |
Kind |
57-173634 |
Oct 1982 |
JPX |
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CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of application Ser. No. 536,896, filed Sept. 28, 1983, which application is now abandoned and is incorporated herein by reference.
US Referenced Citations (4)
Foreign Referenced Citations (1)
Number |
Date |
Country |
1533050 |
Sep 1979 |
GBX |
Non-Patent Literature Citations (2)
Entry |
U.S. patent application Ser. No. 256,839, filed 4/23/81. |
European Search Report from EP 83305952.0. |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
536896 |
Sep 1983 |
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