Gas separation – Two or more separators – Plies or layers of different characteristics or orientation
Patent
1998-08-28
2000-02-29
Spitzer, Robert H.
Gas separation
Two or more separators
Plies or layers of different characteristics or orientation
55524, 55528, 96 13, B01D 4610
Patent
active
060304286
ABSTRACT:
A fine powder of polytetrafluoroethylene is mixed with a liquid lubricant, and the mixture is molded into an unsintered sheet by at least one of an extrusion method and a rolling method. The liquid lubricant is removed from the sheet by at least one of a heating method and an extrusion method. This sheet-form molding is stretched in the machine direction to produce a sheet-form polytetrafluoroethylene molding which, upon analysis with a differential scanning calorimeter, gives a crystal fusion curve having an endothermic peak in the temperature range of 345.+-.5.degree. C. and which has a degree of crystallization of from 0.1 to 0.85 and a specific gravity of 1.4 or lower. The molding is then stretched in the transverse direction to produce a porous polytetrafluoroethylene (PTFE) membrane. The process is effective in producing, with good reproducibility, a useful porous PTFE membrane which has a high collection efficiency and a low pressure loss and is reduced in the leakage of coarse particles.
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Abstract of Japan 7-196,831 (Published Aug. 1, 1995).
Ishino Toshiaki
Maeoka Takuya
Nabata Norikane
Nitto Denko Corporation
Spitzer Robert H.
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