EP0087149A2
Expired / Lapsed
EP
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Semisintered polytetrafluoroethylene article and production thereof
Assignee: Daikin Industries Ltd
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Filing: 1983-02-19
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Granted: —
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Expires: 2003-02-19
Abstract
Abstract A semisintered polytetrafluoroethylene article which is prepared by heating at least a part of an unsintered polytetrafluoroethylene article at a temperature of at least a melting point of a sintered polymer, the heated part of the article having an endothermic curve at a temperature of 345 ± 5°C on a crystalline melting chart measured with a differential scanning carolimeter and the crystalline conversion of from 0.10 to 0.85 defined by heat of fusion of the unsintered, semisintered and sintered polymer, and the crystallinity of the heated surface of the semisintered article measured by X-ray diffraction being from 80 to 93 % being expandable biaxially to afford a porous polytetrafluoroethylene material having an almost unporous surface.
Inventors
- 👤 Katsutoshi Yamamoto
- 👤 Syoji Kawachi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-23 14:18
CPC Classifications
C; C08; C08J; C08J5/00; C08J5/18; B; B29; B29C; B29C48/00; B29C48/022; B29C48/03; B29C48/07; B29C48/08; B29C55/00; B29C55/005; B29C67/00; B29C67/02; B29C67/04; C08J9/00; B29C48/06; B29C48/09; B29C48/10; B29K; B29K2027/00; B29K2027/12; B29K2027/18; C08J2327/00; C08J2327/02; C08J2327/12; C08J2327/18
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
101 words
A semisintered polytetrafluoroethylene article which is prepared by heating at least a part of an unsintered polytetrafluoroethylene article at a temperature of at least a melting point of a sintered polymer, the heated part of the article having an endothermic curve at a temperature of 345 ± 5°C on a crystalline melting chart measured with a differential scanning carolimeter and the crystalline conversion of from 0.10 to 0.85 defined by heat of fusion of the unsintered, semisintered and sintered polymers, and the crystallinity of the heated portion of the semisintered article measured by X-ray diffraction being from 80 to 93 %.
Claim 2
Dependent Claim
101 words
A semisintered polytetrafluoroethylene article which is prepared by heating at least a part of an unsintered polytetrafluoroethylene article at a temperature of at least a melting point of a sintered polymer, the heated part of the article having an endothermic curve at a temperature of 345 ± 5°C on a crystalline melting chart measured with a differential scanning carolimeter and the crystalline conversion of from 0.10 to 0.85 defined by heat of fusion of the unsintered, semisintered and sintered polymers, and the crystallinity of the heated portion of the semisintered article measured by X-ray diffraction being from 80 to 93 %.
Claim 3
Dependent Claim
16 words
The semisintered article according to claim 1, wherein the crystalline conversion is from 0.15 to 0.70.
Claim 4
Dependent Claim
16 words
The semisintered article according to claim 1, wherein the crystallinity is from 85 to 92 %.
Claim 5
Dependent Claim
23 words
The semisintered article according to claim 1, wherein the specific gravity of the heated surface of the semisintered article is at least 1.80.
Claim 6
Dependent Claim
19 words
The semisintered article according to claim 1, wherein the unsintered article has a specific gravity of at least 1.4.
Claim 7
Dependent Claim
24 words
The semisintered article according to claim 1, wherein the unsintered article is a sheet or a film having a thickness less than 0.2 mm.
Claim 8
Dependent Claim
88 words
The semisintcred article according to claim 1, wherein the unsintered article is a sheet or a film having a thickness of at least 0.2 mm, a tube having a wall thickness of at least 0.2 mm or a rod having a diameter of at least 0.2 mm, and the surface layer having thickness of at least 0.1 mm on at least one surface of the heated article or at least 0.1 % of the cross section of the heated article has the properties as defined in claim 1.
Claim 9
Dependent Claim
40 words
A process for producing a semisintered article according to any one of claims 1 to 7, which comprises heating at least a part of an unsintered polytetrafluoroethylene article at a temperature of at least a melting point of sintered polytetrafluoroethylene.
Claim 10
Dependent Claim
32 words
The process according to claim 8, wherein the heating is carried out at a temperature of from the melting point of the sintered polymer to the melting point of the unsintered polymer.
Claim 11
Dependent Claim
35 words
A process for producing a porous polytetrafluoroethylene material, which comprises expanding a semisintered article according to any one of claims 1 to 7 at a temperature lower than the melting point of the unsintered polymer.
Claim 12
Dependent Claim
12 words
A porous polytetrafluoroethylene material prepared by the process according to claim 10.
References Cited (Backward Citations)
No citation records indexed.
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