Particle-filled microporous materials
AssigneeMinnesota Mining and Manufacturing Company
InventorsJerome W. McAllister, Kevin E. Kinzer, James S. Mrozinski, Eric J. Johnson, James F. Dyrud
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Abstract
A microporous particulate-filled thermoplastic polymeric article is provided. The article can be in the form of a film, a fiber, or a tube. The article has a thermoplastic polymeric structure having a plurality of interconnected passageways to provide a network of communicating pores. The microporous structure contains discrete submicron or low micron-sized particulate filler, the particulate filler being substantially non-agglomerated.
Claims34
A method for preparing a particulate-filled microporous thermoplastic polymeric shaped article which comprises the steps of
- (a) dispersing submicron or micron-sized particulate filler in a liquid compatible with the thermoplastic polymer to form a colloidal suspension of the particulate filler in the liquid, the particulate filler being substantially non-agglomerated;
- (b) melt-blending the thermoplastic polymer with a solubilizing amount of the compatible liquid containing the dispersed particulate filler at a temperature sufficient to form a homogeneous solution;
- (c) forming an article from the solution;
- (d) cooling the shaped article at a rate and to a temperature sufficient to initiate thermodynamic, non-equilibrium phase separation;
- (e) further cooling the article to solidify the thermoplastic polymer;
- and
- (f) removing at least a substantial portion of the compatible liquid, said particulate filler remaining substantially entirely within the thermoplastic polymer article.
Dependencies are inferred from the claim text.