Process of making microporous membranes from poly(etheretherketone)-type polymers and low melting point crystallizable polymers
AssigneeThe Dow Chemical Company
InventorsRobert D. Mahoney, H. Nelson Beck, Richard A. Lundgard, Hawk S. Wan, Jiro Kawamoto, Mark F. Sonnenschein
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Abstract
The invention relates to a process for preparing a microporous membrane from an unsulfonated poly(etheretherketone)-type polymer by forming a mixture of an unsulfonated poly(etheretherketone)-type polymer, a low melting point crystallizable polymer, and a plasticizer, heating the resulting mixture, extruding or casting the mixture into a membrane, quenching or coagulating the membrane, and leaching the membrane, while optionally drawing the membrane before, during, after leaching, or a combination thereof.
Claims25
A process for preparing a microporous membrane from an unsulfonated poly(etheretherketone)-type polymer comprising the steps of:
- A. forming a mixture comprising:
- (i) at least one unsulfonated poly(etheretherketone)-type polymer, and
- (ii) at least one low melting point crystallizable polymer which is at least partially incompatible with said poly(etheretherketone)-type polymer and which possesses a melting point of less than about (Tm -30.degree. C.), wherein Tm is the melting point of said poly(etheretherketone)-type polymer, and a molecular weight of at least about 400;
- B. heating said mixture to a temperature at which said mixture becomes a fluid;
- C. extruding or casting said fluid under conditions such that a membrane is formed;
- and
- D. leaching said membrane under conditions such that at least a portion of said low melting point crystallizable polymer is removed from said membrane.
A process for preparing a microporous membrane from an unsulfonated poly(etheretherketone)-type polymer which comprises the steps of:
- A. forming a mixture comprising:
- (i) at least one unsulfonated poly(etheretherketone)-type polymer,
- (ii) at least one low melting point crystallizable polymer which is at least partially incompatible with said poly(etheretherketone)-type polymer and which possesses a melting point of less than about (Tm -30.degree. C.), wherein Tm is the melting point of said poly(etheretherketone)-type polymer, and a molecular weight of at least about 400, and
- (iii) a plasticizer comprising at least one organic compound capable of dissolving at least about 10 weight percent of said poly(etheretherketone)-type polymer at the extrusion or casting temperature;
- B. heating said mixture to a temperature at which said mixture becomes a fluid;
- C. extruding or casting said fluid under conditions such that a membrane is formed;
- and
- D. leaching said membrane under conditions such that at least a portion of said low melting point crystallizable polymer, at least a portion of said plasticizer, or combination thereof, is removed from said membrane.
Dependencies are inferred from the claim text.