Corona treatment of perforated film

Abstract From the Canadian patent

Abstract of the Disclosure A perforated thermoplastic film with tapered capillaries which has an increased liquid flow rate through the tapered capillaries and a method for making such a film. The method includes subjecting a perforated thermoplastic film having tapered capillaries to a corona discharge treatment sufficient to increase the flow rate of liquid through said perforated film. The film made in accordance with the invention has a much higher liquid transmission rate than the perforated film of the prior art. Furthermore, the film may be treated with a corona discharge continuously as the film is being formed and perforated.