1
Elton Robert L, Vander Louw John F: Stretch-oriented porous films and preparation and use thereof. Minnesota Mining and Manufacturing Company, Alexander Sell Steldt & DeLaHunt, March 11, 1975: US3870593 (101 worldwide citation)

Porosity (preferably microporosity) can be introduced into a polymeric film by (1) dispersing finely divided particles of a non-hygroscopic inorganic salt such as calcium carbonate into a suitable polymer, e.g., by milling, (2) forming a film of the filled polymer, and (3) stretching the film to pro ...


2
Elton Robert L, Vander Louw John F: Method of making stretch-oriented porous films. Minnesota Mining and Manufacturing Company, Alexander Sell Steldt & DeLaHunt, October 29, 1974: US3844865 (58 worldwide citation)

Porosity (preferably microporosity) can be introduced into a polymeric film by (1) dispersing finely divided particles of a non-hygroscopic inorganic salt such as calcium carbonate into a suitable polymer, e.g., by milling, (2) forming a film of the filled polymer, and (3) stretching the film to pro ...