Porous film and porous film manufacturing apparatus.

摘要

This invention provides a porous film (76) useful as a fresh fruit and vegetable wrapping material which is obtained by forming a large number of small recesses (74) in an organic film (69) and which does not allow permeation of water, bacteria, and viruses, but allows permeation of a gas, e.g., the oxygen gas or the carbon dioxide gas, and water vapor. The porous film (76) includes the organic film (69) and the large number of recesses (74) formed in the organic film (69) and having an average opening width of 0.5 <0>m to 300 <0>m and inner surfaces exhibiting affinity. The invention provides as well a porous film manufacturing apparatus comprising: feed means for feeding an elongated organic film (69; a recess-forming unit (29) including a first rotatable roll (9) having a surface on which a large number of dielectric particles (10), each having sharp pointed portions and a Mohs hardness value of not less than 5, are deposited, and a second roll (16) which is rotatable in a direction reverse to a rotating direction of the first roll and having a surface on which a dielectric layer is formed, the first and second rolls being arranged to cause the elongated organic film to pass therebetween, and either one or both of the rolls being movable in a direction along which the first and second rolls (9), (16) are aligned; pressure control means (53), arranged near two end portions of either one of the rolls (9), (16) of the recess-forming unit (29), for controlling a pressure applied from each of the rolls to the elongated organic film (69); and high-voltage supply means for supplying a high voltage to the first roll.