Patent US4456570A successfully refreshed from Google Patents.
US4456570A
Expired / Lapsed
US
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Treatment of perforated film
Assignee: Tredegar Film Products LLC
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Filing: 1982-07-26
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Granted: 1984-06-26
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Expires: 2002-07-26
Abstract
Abstract A perforated thermoplastic film with less than ideally shaped tapered capillaries which has an increased liquid flow rate through the tapered capillaries and a method for making such a film. The method includes forming a perforated thermoplastic film having tapered capillaries from a resin into which an effective amount of a polarizable, migrating surfactant has been blended therewith and then treating the perforated thermoplastic film with a corona discharge treatment sufficient to increase the flow rate of liquid through said perforated film and provide a film having a percent run off of from about zero to ten percent. The perforated film made in accordance with the invention has a much higher liquid transmission rate than similarly made non-surfactant treated perforated film having tapered capillaries which has been treated only with a corona discharge treatment. The latter may be conducted 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
2026-11-01 04:58
CPC Classifications
B; B29; B29C; B29C59/00; B29C59/02; B29C59/06; B29C59/10; B29K; B29K2023/00
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
104 words
A method of preparing a perforated sheet comprising polymeric material utilizing non-welded screens comprising the steps of: (a) shaping into the form of a sheet, a resin selected from the group consisting of polyethylene and copolymers of ethylene and propylene, and blended therewith an effective small amount of a polarizable migrating surfactant up to about 10 percent by weight of the resin; (b) perforating said sheet utilizing a non-welded screen; (c) subjecting at least one surface of the perforated sheet to corona discharge treatment; and, (d) recovering a perforated plastic sheet having a percent run off from zero to less than about ten percent.
Claim 2
Independent Claim
104 words
A method of preparing a perforated sheet comprising polymeric material utilizing non-welded screens comprising the steps of: (a) shaping into the form of a sheet, a resin selected from the group consisting of polyethylene and copolymers of ethylene and propylene, and blended therewith an effective small amount of a polarizable migrating surfactant up to about 10 percent by weight of the resin; (b) perforating said sheet utilizing a non-welded screen; (c) subjecting at least one surface of the perforated sheet to corona discharge treatment; and, (d) recovering a perforated plastic sheet having a percent run off from zero to less than about ten percent.
Claim 3
Dependent Claim
16 words
The method of claim 1 wherein the surfactant is an antistatic agent or an antifog agent.
Claim 4
Dependent Claim
17 words
The method of claim 1, whereby the sheet formed has a percent run off of substantially zero.
Claim 5
Dependent Claim
122 words
A procoss for increasing the liquid flow through perforated thermoplastic film having tapered capillaries, comprising: (a) on non-welded screens forming a perforated thermoplastic film having tapered capillaries from a polyolefin resin into which an effective small amount of a polarizable migrating surfactant up to about 10 percent by weight of the polyolefin resin has been blended therewith; and (b) subjecting said surfactant treated perforated thermoplastic film having tapered capillaries to a corona discharge threatment sufficient to provide a perforated film having an increased liquid flow through rate over that of non-surfactant treated perforated thermoplastic film after corona discharge treatment and said surfactant treated and corona discharge treated film having a percent run off of from 0 percent to less than 10 percent.
Claim 6
Dependent Claim
122 words
A procoss for increasing the liquid flow through perforated thermoplastic film having tapered capillaries, comprising: (a) on non-welded screens forming a perforated thermoplastic film having tapered capillaries from a polyolefin resin into which an effective small amount of a polarizable migrating surfactant up to about 10 percent by weight of the polyolefin resin has been blended therewith; and (b) subjecting said surfactant treated perforated thermoplastic film having tapered capillaries to a corona discharge threatment sufficient to provide a perforated film having an increased liquid flow through rate over that of non-surfactant treated perforated thermoplastic film after corona discharge treatment and said surfactant treated and corona discharge treated film having a percent run off of from 0 percent to less than 10 percent.
Claim 7
Dependent Claim
18 words
The process of claim 4, wherein the tapered capillaries of said perforated thermoplastic film have curved side walls.
Claim 8
Dependent Claim
26 words
The process of claim 4 wherein the surface treated and corona discharge treated film has a run off percent of from 0 percent to 5 percent.
Claim 9
Dependent Claim
13 words
The process of claim 4 wherein said polyolefin resin is low density polyethylene.
Claim 10
Dependent Claim
11 words
The process of claim 4 wherein said polyolefin resin is polypropylene.
Claim 11
Dependent Claim
13 words
The process of claim 4, wherein said polarizable, migrating surfactant largely comprises monoglycerides.
Claim 12
Dependent Claim
18 words
The process of claim 4, wherein the percent by weight of said polarizable migrating surfactant is about five.
Claim 13
Dependent Claim
168 words
In a process for the preparation of perforated thermoplastic film having tapered capillaries of less than ideal dimensions, said process comprising forming a hot film of thermoplastic material, applying the hot film to a moving, non-welded perforated screen and applying an air pressure differential across the film toward a portion of the non-welded screen sufficient to distort the film into the perforations and cause rupture of the film, the improvement comprising blending with a polyolefin resin an effective small amount of a polarizable migrating surfactant up to about 10 percent by weight of the polyolefin resin prior to forming a hot film of thermoplastic material from said resin and subjecting the perforated film to a corona discharge treatment sufficient to provide a perforated film having an increased liquid flow through rate over that of a non-surfactant treated perforated thermoplastic film treated only with the corona discharge threatment and said surfactant treated and corona discharge treated film having a percent run off of from 0 percent to 10 percent.
Claim 14
Dependent Claim
168 words
In a process for the preparation of perforated thermoplastic film having tapered capillaries of less than ideal dimensions, said process comprising forming a hot film of thermoplastic material, applying the hot film to a moving, non-welded perforated screen and applying an air pressure differential across the film toward a portion of the non-welded screen sufficient to distort the film into the perforations and cause rupture of the film, the improvement comprising blending with a polyolefin resin an effective small amount of a polarizable migrating surfactant up to about 10 percent by weight of the polyolefin resin prior to forming a hot film of thermoplastic material from said resin and subjecting the perforated film to a corona discharge treatment sufficient to provide a perforated film having an increased liquid flow through rate over that of a non-surfactant treated perforated thermoplastic film treated only with the corona discharge threatment and said surfactant treated and corona discharge treated film having a percent run off of from 0 percent to 10 percent.
Claim 15
Dependent Claim
18 words
The process of claim 11, wherein the tapered capillaries of said perforated thermoplastic film have curved side walls.
Claim 16
Dependent Claim
26 words
The process of claim 11, wherein said surfactant treated and corona discharge treated film has a run off percent of from 0 percent to 5 percent.
Claim 17
Dependent Claim
14 words
The process of claim 11, wherein said film is manufactured from low density polyethylene.
Claim 18
Dependent Claim
13 words
The process of claim 11, wherein said film is made from polypropylene resin.
Claim 19
Dependent Claim
13 words
The process of claim 11 wherein said polarizable migrating surfactant is largely monoglycerides.
Claim 20
Dependent Claim
19 words
The process of claim 11, wherein the percent by weight of said polarizable, migrating surfactant added is about five.
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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) | 1987-06-26 | 1987-12-26 | 1988-06-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-06-26 | 1991-12-26 | 1992-06-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-06-26 | 1995-12-26 | 1996-06-26 | $7700.00 | Window Closed / Lapsed |