Corona treatment of perforated film
AssigneeEthyl Corporation
InventorsPaul E. Thomas, Garland E. Raley
Life of this patent
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Abstract
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.
Claims10
A process for increasing the liquid flow through perforated thermoplastic film having tapered capillaries, comprising:
- a. forming a perforated thermoplastic film having tapered capillaries;
- and,
- b. subjecting said perforated thermoplastic film having tapered capillaries to a corona discharge treatment sufficient to provide a perforated film having an increased liquid flow through rate over that of said perforated thermoplastic film prior to the corona discharge treatment and said film has a percent run off of from 5 percent to 20 percent.
In a process for the preparation of perforated thermoplastic film having tapered capillaries, said process comprising forming a hot film of thermoplastic material, applying the hot film to a moving perforated screen, and applying an air pressure differential across the film toward a portion of the screen sufficient to distort the film into the perforations and cause rupture of the film, the improvement comprising subjecting said perforated film to a corona discharge treatment sufficient to provide a perforated film having an increased liquid flow through rate over that of said perforated thermoplastic film prior to the corona discharge treatment and said film has a percent run off of from 5 percent to 20 percent.
Dependencies are inferred from the claim text.