US4351784A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Corona treatment of perforated film
Assignee: Tredegar Corp
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Filing: 1980-12-15
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Granted: 1982-09-28
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Expires: 2000-12-15
Abstract
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.
Inventors
- 👤 Paul E. Thomas
- 👤 Garland E. Raley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 22:07
CPC Classifications
A; A61; A61F; A61F13/00; A61F13/00987; A61F13/00991; A61F13/15; A61F13/51; A61F13/511; A61F13/51121; A61F13/512; B; B26; B26F; B26F1/00; B26F1/26; B26F1/28; B29; B29C; B29C59/00; B29C59/10; A61F13/15577; A61F2013/15821
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
80 words
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.
Claim 2
Dependent Claim
80 words
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.
Claim 3
Dependent Claim
18 words
The process of claim 1, wherein the tapered capillaries of said perforated thermoplastic film have curved side walls.
Claim 4
Dependent Claim
20 words
The process of claim 1 wherein the film has a run off percent of from 7 percent to 15 percent.
Claim 5
Dependent Claim
12 words
The process of claim 3 wherein said film is low density polyethylene.
Claim 6
Dependent Claim
10 words
The process of claim 3 wherein said film is polypropylene.
Claim 7
Dependent Claim
114 words
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.
Claim 8
Dependent Claim
114 words
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.
Claim 9
Dependent Claim
18 words
The process of claim 6 wherein the tapered capillaries of said perforated thermoplastic film have curved side walls.
Claim 10
Dependent Claim
20 words
The process of claim 6 wherein said film has a run off percent of from 7 percent to 15 percent.
Claim 11
Dependent Claim
12 words
The process of claim 8 wherein said film is low density polyethylene.
Claim 12
Dependent Claim
10 words
The process of claim 8 wherein said film is polypropylene.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-09-27 | 1986-03-29 | 1986-09-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-09-27 | 1990-03-29 | 1990-09-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-09-27 | 1994-03-29 | 1994-09-28 | $7700.00 | Window Closed / Lapsed |