Howard W Malarkey

US Patent:

50322745, Jul 16, 1991

Filed:

Aug 17, 1990

Appl. No.:

7/569060

Inventors:

Larry Y. Yen - Tewksbury MA
George Lopatin - Newton Centre MA
Howard Malarkey - Lowell MA
David Soane - Piedmont CA

Assignee:

Millipore Corporation - Bedford MA

International Classification:

B01D 7132

US Classification:

21050042

Abstract:

Microporous or open ultrafiltration poly (tetrafluoroethylene-co-perfluoro-(alkyl vinyl ether)) (PFA) or poly (tetrafluoroethylene-co-hexafluoropropylene) (FEP) film membrane or hollow fibers having open pores are formed from a melt blend of 10 to 35 weight percent of the PFA or FEP and a chlorotrifluoroethylene oligomer solvent. The melt blend is shaped and one or more surfaces of the shaped melt blend are coated with the solvent prior to phase separation of the melt blend. Coating the membrane with solvent during shaping results in membrane having larger pores on that membrane surface as compared to membranes not coated with solvent. The shaped melt blend is cooled to effect phase separation and crystallization of the PFA or FEP from the blend. The solvent is separated from the PFA or FEP by extraction and the porous PFA or FEP is heat set under restraint to prevent shrinkage. In one embodiment of this invention the dry film membrane recovered after extraction or the membrane wet with extraction liquid is stretched in the cross-web direction to below its breaking limit, dried restrained and then heat-set.

US Patent:

49902946, Feb 5, 1991

Filed:

Sep 26, 1989

Appl. No.:

7/412959

Inventors:

Larry Y. Yen - Tewksbury MA
George Lopatin - Newton Centre MA
Howard Malarkey - Lowell MA
David Soane - Piedmont CA

Assignee:

Millipore Corporation - Bedford MA

International Classification:

C08L 926
B01D 1300

US Classification:

264 41

Abstract:

Microporous or open ultrafiltration poly (tetrafluoroethylene-co-perfluoro-(alkyl vinyl ether)) (PFA) or poly (tetrafluoroethylene-co-hexafluoropropylene) (FEP) film membrane or hollow fibers having open pores are formed from a melt blend of 10 to 35 weight percent of the PFA or FEP and a chlorotrifluoroethylene oligomer solvent. The melt blend is shaped and one or more surfaces of the shaped melt blend are coated with the solvent prior to phase separation of the melt blend. Coating the membrane with solvent during shaping results in membrane having larger pores on that membrane surface as compared to membranes not coated with solvent. The shaped melt blend is cooled to effect phase separation and crystallization of the PFA or FEP from the blend. The solvent is separated from the PFA or FEP by extraction and the porous PFA or FEP is heat set under restraint to prevent shrinkage. In one embodiment of this invention the dry film membrane recovered after extraction or the membrane wet with extraction liquid is stretched in the cross-web direction to below its breaking limit, dried, restrained and then heat-set.