← Back to Patent Explorer
EP0172750A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Porous structures

Assignee: EIDP Inc
•
Filing: 1985-08-20
•
Granted: —
•
Expires: 2005-08-20
📄 Original PDF 🌐 Google Patents 🔄 Sync Now

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 the melting point of the 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 calorimeter and a 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 78 to 95%.

Inventors

  • 👤 Paul Smith

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-10-23 10:02
CPC Classifications
B; B29; B29C; B29C67/00; B29C67/20; B29C67/205; B29C48/00; B29C48/03; B29C55/00; B29K; B29K2027/00; B29K2027/12; B29K2027/18

Claims Analysis

Total Claims: 5
Claim 1
Independent Claim 36 words
A process for producing a semisintered polytetrafluoroethylene article which comprises heating an unsintered granular polytetrafluoroethylene article while under compression at a temperature of between 332 and 345°C and then stretching the article at a lower temperature.
Claim 2
Dependent Claim 36 words
A process for producing a semisintered polytetrafluoroethylene article which comprises heating an unsintered granular polytetrafluoroethylene article while under compression at a temperature of between 332 and 345°C and then stretching the article at a lower temperature.
Claim 3
Dependent Claim 19 words
A process according to claim 1 wherein the unsintered granular polytetrafluoroethylene has a specific gravity of 1.4 to 1.7.
Claim 4
Dependent Claim 26 words
A process according to claim 1 or 2 wherein the article is under compression of 7.8 to 1.2 MPa (80 to 120 kg/cm 2 ) pressure.
Claim 5
Dependent Claim 25 words
A process according to claim 1, 2 or 3 wherein the heated article is cooled to less than 200°C and expanded in a separate stage.

References Cited (Backward Citations)

No citation records indexed.

USPTO Annuity & Maintenance Windows

Maintenance schedule is calculated for granted US utility patents.

Assigned Categories & Tags

No categories assigned to this patent yet.

Assign Category Tag