US3729536A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of producing water vapor permeable sheet material
Assignee: Porvair PLC
•
Filing: 1970-06-02
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Granted: 1973-04-24
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Expires: 1990-06-02
Abstract
Abstract Coagulation process and apparatus for producing thick microporous polyurethane sheet material by passing a sheet of polymer extended with liquid vehicle beneath a close spaced plate with liquid non-solvent fed to the gap between the plate and the surface to produce controlled imitation of the coagulation.
Inventors
- 👤 Eric Albert Warwicker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 04:06
CPC Classifications
D; D06; D06N; D06N3/00; D06N3/12; D06N3/14; B; B29; B29C; B29C44/00; B29C44/20; B29C48/00; B29C48/03; B29C48/07; B29C48/08; B29C48/25; B29C48/88; B29C48/911; B29C48/9135; B29C48/9145; B29C48/919; C; C08; C08J; C08J9/00; C08J9/26; Y; Y10; Y10S; Y10S264/00; Y10S264/62; Y10S264/77
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
51 words
A method as in claim 1 in which the said polymer composition comprising a solution of thermoplastic elastomeric polyurethane in a liquid selected from the group consisting of dimethyl formamide and blends of dimethyl formamide and water, microscopic particles of a water soluble inorganic salt being dispersed through said polymer composition.
Claim 2
Dependent Claim
53 words
Process as in claim 1 in which the speed of said free surface of said layer of polymer composition with respect to said first mentioned line is less than 15 feet per minute, and said layer of polymer composition is maintained on the support until the layer is coagulated to self supporting form.
Claim 3
Dependent Claim
22 words
A method as claimed in claim 1 in which the distance between said lines is maintained substantially constant during the relative movement.
Claim 4
Dependent Claim
33 words
Process as in claim 1 in which said layer of polymer composition is arranged uppermost on said support and there is a meniscus of coagulating liquid extending between said first and second lines.
Claim 5
Dependent Claim
81 words
Process as in claim 1 in which said support is porous, said solid boundary is stationary, said support carrying said layer is moved continuously, the speed of said support and layer of polymer composition with respect to said first mentioned line is less than 15 feet per minute, said body of coagulating liquid extends downstream (taken in the direction of movement of said support and layer) of said solid boundary, and said layer and said support pass under said solid boundary.
Claim 6
Dependent Claim
16 words
Process as in claim 6 in which said speed is 1 to 10 feet per minute.
Claim 7
Dependent Claim
65 words
A method as claimed in claim 6 in which prior to the application of the layer of polymer composition to the porous support the porous support is dried and liquid non-solvent is evenly applied thereto so as to ensure even penetration of the support by the layer of polymer composition and that the coagulation caused by the non-solvent content of the belt is also even.
Claim 8
Dependent Claim
28 words
A method as claimed in claim 8 in which the support carries 50 to 80 percent by weight based on its own weight of the non solvent liquid.
Claim 9
Dependent Claim
28 words
A method as claimed in claim 8 in which the non-solvent liquid comprises 5 to 40 percent by weight of the liquid vehicle the balance being liquid non-solvent.
Claim 10
Dependent Claim
38 words
Process as in claim 1 in which said porous support has an underside which also contacts said body of coagulating liquid, said polymer composition and coagulating liquid being such that a microporous layer is produced by the process.
Claim 11
Dependent Claim
82 words
Process as in claim 6 in which said solid boundary is in such relationship to said layer of polymer composition that there is an elongated narrow gap between said layer and said boundary, which gap is filled with coagulating liquid, and said coagulating liquid is so supplied as to form a thin layer thereof over the free surface of said layer of polymer composition, the thickness of said thin layer of liquid being in the range of 0.1 mm to 1 cm.
Claim 12
Dependent Claim
33 words
Process as in claim 12 in which the thickness of said thin layer of liquid is 1 to 5 mm and in which coagulating liquid is continuously supplied to said thin layer thereof.
Claim 13
Dependent Claim
20 words
Process as in claim 12 in which the width of said gap is in the range 0.1 to 8 mm.
Claim 14
Dependent Claim
20 words
Process as in claim 12 in which the width of said gap is in the range 2 to 7 mm.
Claim 15
Independent Claim
147 words
A method of making a water vapor permeable polymer sheet material which comprises forming an initial mixture comprising elastomeric thermoplastic polyurethane dissolved in dimethylformamide with microscopic water soluble inorganic salt particles dispersed through the mixture, forming a layer at least 0.5 mm thick of the initial mixture in adherence with a support, passing the layer in adherence with the support past a plate spaced from the free surface of the said layer a distance such that on supplying an aqueous non solvent liquid to The gap between the plate and the layer a meniscus is formed at the upstream end of the gap and supplying the said aqueous non-solvent for the polymer to the said gap so as to establish and maintain the said meniscus of non solvent at the upstream end of the gap and coagulating said layer by the action of aqueous non-solvent liquid thereon.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-04-23 | 1976-10-23 | 1977-04-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-23 | 1980-10-23 | 1981-04-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-23 | 1984-10-23 | 1985-04-24 | $7700.00 | Window Closed / Lapsed |