US4760102A
Expired / Lapsed
US
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Porous polytetrafluoroethylene material
Assignee: Daikin Industries Ltd
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Filing: 1986-07-15
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Granted: 1988-07-26
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Expires: 2006-07-15
Abstract
Abstract A porous polytetrafluoroethylene material produced by forming a mixture of an adequate amount of a liquid lubricant and polytetrafluoroethylene fine powder having an average molecular weight of at least 6,000,000, an amorphous index larger than 0.1 and a number average primary particle size of 0.1 to 0.8 microns, and a clear endothermic peak at a temperature of 347+/-3 DEG C. and an another endothermic peak or shoulder at a temperature between 330 DEG C. and the temperature of said clear endothermic peak on a crystalline melting chart recorded by a differential scanning calorimeter, removing the lubricant to obtain an unsintered PTFE material and expanding the unsintered polytetrafluoroethylene material at least monoaxially at a temperature higher than the melting point of polytetrafluoroethylene.
Inventors
- 👤 Yasuhiro Moriyama
- 👤 Shoji Suzuki
- 👤 Atsuo Yoshimura
- 👤 Kanji Kawakami
- 👤 Jyuzaemon Hoashi
- 👤 Syozo Fumoto
- 👤 Kiyoshi Oshita
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 11:25
CPC Classifications
C; C08; C08J; C08J5/00; C08J5/18; B; B29; B29C; B29C55/00; B29C55/005; B29C67/00; B29C67/20; B29C67/202; C08J9/00; C08J9/28; B29K; B29K2027/00; B29K2027/12; B29K2027/18; B29K2105/00; B29K2105/04; C08J2327/00; C08J2327/02; C08J2327/12; C08J2327/18; Y; Y10; Y10S; Y10S521/00; Y10S521/919
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
122 words
A porous polytetrafluoroethylene material having a tensile strength of 356 to 723 Kg/cm 2 produced by: forming a mixture of an adequate amount of a liquid lubricant and polytetrafluoroethylene fine powder having an average molecular weight of at least 6,000,000 an amorphous index larger than 0.1, and a clear endothermic peak at a temperature of 347±3° C. and another endothermic peak or shoulder at a temperture between 330° C. and the temperature of said clear endothermic peak on a crystalline melting chart recorded by a differential scanning calorimeter; removing the lubricant to obtain an unsintered polytetrafluoroethylene material; and simultaneously expanding the unsintered polytetrafluoroethylene material at least monoaxially and sintering the polytetrafluoroethylene material at a temperature higher than the melting point of polytetrafluoroethylene.
Claim 2
Dependent Claim
122 words
A porous polytetrafluoroethylene material having a tensile strength of 356 to 723 Kg/cm 2 produced by: forming a mixture of an adequate amount of a liquid lubricant and polytetrafluoroethylene fine powder having an average molecular weight of at least 6,000,000 an amorphous index larger than 0.1, and a clear endothermic peak at a temperature of 347±3° C. and another endothermic peak or shoulder at a temperture between 330° C. and the temperature of said clear endothermic peak on a crystalline melting chart recorded by a differential scanning calorimeter; removing the lubricant to obtain an unsintered polytetrafluoroethylene material; and simultaneously expanding the unsintered polytetrafluoroethylene material at least monoaxially and sintering the polytetrafluoroethylene material at a temperature higher than the melting point of polytetrafluoroethylene.
Claim 3
Dependent Claim
20 words
A porous polytetrafluoroethylene material according to claim 1, wherein the molecular weight of the fine powder is at least 6,500,000.
Claim 4
Dependent Claim
20 words
A porous polytetrafluoroethylene material according to claim 1, wherein the amorphous index of the fine powder is larger than 0.11.
Claim 5
Dependent Claim
23 words
A porous polytetrafluoroethylene material according to claim 1, wherein the endothermic ratio as defined hereinbefore of the fine powder is larger than 0.30.
Claim 6
Dependent Claim
27 words
A porous polytetrafluoroethylene material according to claim 1, wherein the critical thickness of devirification of the film formed from the fine powder is 20 to 45 microns.
Claim 7
Dependent Claim
62 words
A porous polytetrafluoroethylene material according to claim 1, wherein the fine powder is prepared by emulsion polymerizing tetrafluoroethylene in an aqueous medium in the presence of an anionic surfactant, an emulsion stabilizer which is liquid under the polymerization conditions and a water-soluble polymerization initiator, at a temperature of lower than 20° C. under a pressure of 5 to 20 Kg/cm 2 .
Claim 8
Dependent Claim
28 words
A porous polytetrafluoroethylene material according to claim 1, which is formed from a polytetrafluoroethylene fine powder having a number average primary particle size of 0.1 to 0.8 microns.
Claim 9
Dependent Claim
205 words
A porous formed article of polytetrafluoroethylene material having a tensile strength of 356 to 723 Kg/cm 2 produced by: forming a mixture consisting essentially of polytetrafluoroethylene fine powder having an average molecular weight of at least 6,000,000, an amorphous index 1a than 0.1 and a number average primary particle size of 0.1 to microns, and a clear endothermic peak at a temperature of 347±3° C. and another endothermic peak or shoulder at a temperature between 330° C. and the temperature of said clear endothermic peak on a crystalline melting chart recorded by a differential scanning calorimeter and 5 to 50 parts by weight of a liquid lubricant per 100 parts by weight of the polytetrafluoroethylene fine powder; extruding the mixture to prepare a formed article; removing the lubricant from the formed article to obtain an unsintered formed article; and simultaneously stretching the unsintered formed article at a draw ratio of about 15 to 750% at least monoaxially and sintering at a temperature higher than the melting pont of PTGE of about 340 to 410° C. for 0.1 to 5 minutes to form a sintered porous formed article with a porosity of about 35 to 90% and a pore size of about 0.01 to 50 microns.
Claim 10
Dependent Claim
205 words
A porous formed article of polytetrafluoroethylene material having a tensile strength of 356 to 723 Kg/cm 2 produced by: forming a mixture consisting essentially of polytetrafluoroethylene fine powder having an average molecular weight of at least 6,000,000, an amorphous index 1a than 0.1 and a number average primary particle size of 0.1 to microns, and a clear endothermic peak at a temperature of 347±3° C. and another endothermic peak or shoulder at a temperature between 330° C. and the temperature of said clear endothermic peak on a crystalline melting chart recorded by a differential scanning calorimeter and 5 to 50 parts by weight of a liquid lubricant per 100 parts by weight of the polytetrafluoroethylene fine powder; extruding the mixture to prepare a formed article; removing the lubricant from the formed article to obtain an unsintered formed article; and simultaneously stretching the unsintered formed article at a draw ratio of about 15 to 750% at least monoaxially and sintering at a temperature higher than the melting pont of PTGE of about 340 to 410° C. for 0.1 to 5 minutes to form a sintered porous formed article with a porosity of about 35 to 90% and a pore size of about 0.01 to 50 microns.
Claim 11
Dependent Claim
20 words
A porous formed article according to claim 8, wherein the molecular weight of the fine powder is at least 6,500,000.
Claim 12
Dependent Claim
20 words
A porous formed article according to claim 8, wherein the amorphous index of the fine powder is larger than 0.11.
Claim 13
Dependent Claim
23 words
A porous formed article according to claim 8, wherein the endothermic ratio as defined hereinbefore of the fine powder is larger than 0.30.
Claim 14
Dependent Claim
27 words
A porous formed article according to claim 8, wherein the critical thickness of devirificaton of the film formed from the fine powder is 20 to 45 microns.
Claim 15
Dependent Claim
62 words
A porous formed article according to claim 8, wherein the fine powder is prepared by emulsion polymerizing tetrafluoroethylene in an aqueous medium in the presence of an anionic surfactant, an emulsion stabilizer which is liquid under the polymerization conditions and a water-soluble polymerization initiator, at a temperature of lower than 20° C. under a pressure of 5 to 20 Kg/cm 2 .
Claim 16
Dependent Claim
14 words
A porous formed article according to claim 8, in the form of a film.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-07-26 | 1992-01-25 | 1992-07-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-07-26 | 1996-01-25 | 1996-07-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-07-26 | 2000-01-25 | 2000-07-26 | $7700.00 | Window Closed / Lapsed |