CA1242556A
Expired / Lapsed
CA
⏱️ 0.0 years remaining
Porous polytetrafluoroethylene material
Assignee: Daikin Industries Ltd
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Filing: 1983-12-14
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Granted: 1988-10-04
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Expires: 2003-12-14
Abstract
Abstract Abstract: The invention provides a porous polytetrafluoro-ethylene material produced by forming a mixture of a suitable amount of a liquid lubricant and a fine powder of polytetra-fluoroethylene 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°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, 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 the polytetra-fluoroethylene.
Inventors
- 👤 Syozo Fumoto
- 👤 Jyuzaemon Hoashi
- 👤 Kiyoshi Oshita
- 👤 Atsuo Yoshimura
- 👤 Shoji Suzuki
- 👤 Yasuhiro Moriyama
- 👤 Kanji Kawakami
Bibliographic Details
Application Number
—
Jurisdiction
CA
Data Source
google_patents
Last Synchronized
2026-11-09 20:38
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
124 words
A porous polytetrafluoroethylene material produced by: forming a mixture of an adequate amount of a liquid lubricant and a 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 temperature between 330°C and the temperature of said clear endothermic peak on a crystalline melting chart recorded by a differential scanning calori-meter; extruding the mixture to prepare a formed material; removing the lubricant from the formed material to obtain an unsintered polytetrafluoroethylene material; and simultane-ously expanding the unsintered polytetrafluoroethylene material at least monoaxially and sintering the polytetra-fluoroethylene material at a temperature higher than the melting point of the polytetrafluoroethylene.
Claim 2
Dependent Claim
124 words
A porous polytetrafluoroethylene material produced by: forming a mixture of an adequate amount of a liquid lubricant and a 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 temperature between 330°C and the temperature of said clear endothermic peak on a crystalline melting chart recorded by a differential scanning calori-meter; extruding the mixture to prepare a formed material; removing the lubricant from the formed material to obtain an unsintered polytetrafluoroethylene material; and simultane-ously expanding the unsintered polytetrafluoroethylene material at least monoaxially and sintering the polytetra-fluoroethylene material at a temperature higher than the melting point of the 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
25 words
A porous polytetrafluoroethylene material according to claim 1, claim 2 or claim 3 wherein the endo-thermic ratio of the fine powder is larger than 0.30.
Claim 6
Dependent Claim
32 words
A porous polytetrafluoroethylene material according to claim 1, claim 2 or claim 3 wherein the critical thickness of devitrification of the film formed from the fine powder is 20 to 45 microns.
Claim 7
Dependent Claim
64 words
A porous polytetrafluoroethylene material according to claim 1, claim 2 or claim 3 wherein the fine powder was 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/cm2.
Claim 8
Dependent Claim
28 words
A porous polytetrafluoroethylene material according to claim 1, which is formed from a polytetra-fluoroethylene fine powder having a number average primary particle size of 0.1 to 0.8 microns.
Claim 9
Dependent Claim
194 words
A porous formed article of polytetra-fluoroethylene material 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 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°C and another endothermic peak or shoulder at a temperature be-tween 330°C and the temperature of said clear endothermic peak on a crystalline melting chart recorded by a differ-ential scanning calorimeter and 5 to 50 parts by weight of a liquid lubricant per 100 parts by weight of the poly-tetrafluoroethylene 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 point of PTFE 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
194 words
A porous formed article of polytetra-fluoroethylene material 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 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°C and another endothermic peak or shoulder at a temperature be-tween 330°C and the temperature of said clear endothermic peak on a crystalline melting chart recorded by a differ-ential scanning calorimeter and 5 to 50 parts by weight of a liquid lubricant per 100 parts by weight of the poly-tetrafluoroethylene 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 point of PTFE 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
20 words
A porous formed article according to claim 8, wherein the endothermic ratio of the fine powder is larger than 0.30.
Claim 14
Dependent Claim
26 words
A porous formed article according to claim 8, wherein the critical thickness of devitrification the film formed from the fine powder is 20 to 45 mirons.
Claim 15
Dependent Claim
59 words
A porous formed article according to claim 8, wherein the fine powder was prepared by emulsion poly-merizing 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/cm2.
Claim 16
Dependent Claim
14 words
A porous formed article according to claim 8, in the form of a film.
References Cited (Backward Citations)
No citation records indexed.
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