Patent US4159370A successfully refreshed from Google Patents.
US4159370A
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US
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Polytetrafluoroethylene fine powder and process for producing the same
Assignee: Daikin Industries Ltd
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Filing: 1977-11-11
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Granted: 1979-06-26
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Expires: 1997-11-11
Abstract
Abstract Polytetrafluoroethylene fine powders which have an average molecular weight of not less than 5,000,000, preferably not less than 5,500,000, an amorphous index of not more than 0.1, preferably not more than 0.09, a number average primary particle size of 0.1 to 0.4 micron, preferably 0.15 to 0.38 micron, and a sharp endothermic peak at a temperature between 343 DEG C. and 350 DEG C. on the melting diagram by a differential scanning calorimeter, said sharp peak having an endothermic ratio of not more than 0.3, preferably not more than 0.27, and a half value width of the endothermic peak of not more than 8 degrees, preferably not more than 6 degrees, and a process for producing the polytetrafluoroethylene fine powders. The polytetrafluoroethylene fine powders have an excellent stretchability and are useful for electric wire coating, small diameter tubes, large diameter tubes, sealing tapes and the like.
Inventors
- 👤 Shun Koizumi
- 👤 Shigeru Ichiba
- 👤 Tetsuo Simizu
- 👤 Chuzo Okuno
- 👤 Tosinori Kadowaki
- 👤 Katsutoshi Yamamoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 20:24
CPC Classifications
C; C08; C08F; C08F14/00; C08F14/18; C08F14/26
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
73 words
A polytetrafluoroethylene fine powder which has an average molecular weight of not less than 5,000,000, an amorphous index of not more than 0.1 and a sharp endothermic peak at a temperature between 343° C. and 350° C. on the melting diagram by a differential scanning calorimeter, said sharp peak having an endothermic ratio of not more than 0.3 and a half value width of the endothermic peak of not more than 8 degrees.
Claim 2
Dependent Claim
73 words
A polytetrafluoroethylene fine powder which has an average molecular weight of not less than 5,000,000, an amorphous index of not more than 0.1 and a sharp endothermic peak at a temperature between 343° C. and 350° C. on the melting diagram by a differential scanning calorimeter, said sharp peak having an endothermic ratio of not more than 0.3 and a half value width of the endothermic peak of not more than 8 degrees.
Claim 3
Dependent Claim
18 words
The polytetrafluoroethylene fine powder according to claim 1, wherein the average molecular weight is not less than 5,500,000.
Claim 4
Dependent Claim
30 words
The polytetrafluoroethylene fine powder according to claim 1, wherein the endothermic peak on the melting diagram by a differential scanning calorimeter appears in the region of 345° to 349° C.
Claim 5
Dependent Claim
17 words
The polytetrafluoroethylene fine powder according to claim 1, wherein the endothermic ratio is not more than 0.27.
Claim 6
Dependent Claim
23 words
The polytetrafluoroethylene fine powder according to claim 1, wherein the half value width of the endothermic peak is not more than 6 degrees.
Claim 7
Dependent Claim
229 words
In a process for producing a polytetrafluoroethylene fine powder, which has an average molecular weight of not less than 5,000,000, an amorphous index of not more than 0.1 and a sharp endothermic peak at a temperature between 343° C. and 350° C. on the melting diagram by a differential scanning calorimeter, said sharp peak having an endothermic ratio of not more than 0.3 and a half value width of the endothermic peak of not more than 8 degrees. the polymerization reaction at a polymerization temperature of 55° to 86° C. using a water-soluble persulfate as the polymerization initiator in a concentration of 0.002% by weight or less, and changing the polymerization condition after the initiation of polymerization and after the polymer in an amount of at least 25% by weight of the final yield is produced but before at most 85% by weight of the final yield of the polymer is produced, said changing of the polymerization condition being carried out by adding either or both of an alkali and a radical scavenger to the polymerization system or by lowering the polymerization temperature 5° to 30° C. said alkali being added in such an amount that the polymerization system is kept on an alkaline side and said radical scavenger being added in an amount of about 2 to 5 times by weight of the amount of the polymerization initiator.
Claim 8
Dependent Claim
229 words
In a process for producing a polytetrafluoroethylene fine powder, which has an average molecular weight of not less than 5,000,000, an amorphous index of not more than 0.1 and a sharp endothermic peak at a temperature between 343° C. and 350° C. on the melting diagram by a differential scanning calorimeter, said sharp peak having an endothermic ratio of not more than 0.3 and a half value width of the endothermic peak of not more than 8 degrees. the polymerization reaction at a polymerization temperature of 55° to 86° C. using a water-soluble persulfate as the polymerization initiator in a concentration of 0.002% by weight or less, and changing the polymerization condition after the initiation of polymerization and after the polymer in an amount of at least 25% by weight of the final yield is produced but before at most 85% by weight of the final yield of the polymer is produced, said changing of the polymerization condition being carried out by adding either or both of an alkali and a radical scavenger to the polymerization system or by lowering the polymerization temperature 5° to 30° C. said alkali being added in such an amount that the polymerization system is kept on an alkaline side and said radical scavenger being added in an amount of about 2 to 5 times by weight of the amount of the polymerization initiator.
Claim 9
Dependent Claim
24 words
The process according to claim 6, wherein the changing of the polymerization condition is carried out by adding an alkali to the polymerization system.
Claim 10
Dependent Claim
48 words
The process according to claim 7, wherein the addition of the alkali is done after the polymer in an amount of at least 30% by weight of the final yield is produced and before at most 80% by weight of the final yield of the polymer is produced.
Claim 11
Dependent Claim
54 words
The process according to claim 6, wherein the changing of the polymerization condition is carried out by adding a radical scavenger to the polymerization system in an amount of about 2 to 5 times by weight of the amount of the polymerization initiator, said radical scavenger being effective on radicals in the aqueous phase.
Claim 12
Dependent Claim
49 words
The process according to claim 9, wherein the addition of a radical scavenger is done after the polymer in an amount of at least 30% by weight of the final yield is produced and before at most 80% by weight of the final yield of the polymer is produced.
Claim 13
Dependent Claim
31 words
The process according to claim 6, wherein the changing of the polymerization condition is carried out by lowering the polymerization temperature at least 5° C., but not more than 30° C.
Claim 14
Dependent Claim
15 words
The process according to claim 11, wherein the temperature is lowered at least 10° C.
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) | 1982-06-25 | 1982-12-25 | 1983-06-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-06-25 | 1986-12-25 | 1987-06-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-06-25 | 1990-12-25 | 1991-06-26 | $7700.00 | Window Closed / Lapsed |