US3770537A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for preparing a microporous sheet by heat-forming, annealing and leaching
Assignee: 3M Co
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Filing: 1971-04-19
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Granted: 1973-11-06
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Expires: 1991-04-19
Abstract
Abstract In the disclosed method of making a microporous sheet material a heat-formed (extruded, calendered, or pressed) film comprising (1) a polyurethane (preferably combined with an epoxidized soybean oil processing aid - a water insoluble plasticizer can also be included) capable of forming a nonporous film having a storage shear modulus (G'') of about 0.4 to 5 X 108 dynes/cm.2 and a loss tangent at 0.2 cycle/sec. less than 0.5, both measured at 23* C., and (2) distributed throughout the film, a plurality of <30 micron salt (e.g., NaCl) particles, is annealed prior to leaching of the salt from the film with an aqueous medium. The resulting microporous film is useful in making leather-like sheet materials. Preferably, the film is embossed prior to leaching but after annealing.
Inventors
- 👤 R Elton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 18:15
CPC Classifications
D; D06; D06N; D06N3/00; D06N3/0043; D06N3/0052; B; B29; B29C; B29C67/00; B29C67/20; B29C67/202; C; C08; C08J; C08J9/00; C08J9/26; B29C71/00; B29C71/02; B29C2071/022; B29C59/00; B29C59/02; B29C59/04; B29K; B29K2105/00; B29K2105/04; B29K2105/041; B29K2995/00; B29K2995/0037; B29K2995/0072; B29K2995/0074; C08J2325/00; C08J2325/02; C08J2325/04; C08J2325/06; C08J2375/00; Y; Y10; Y10T; Y10T156/00; Y10T156/10; Y10T156/1002; Y10T156/1039
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
20 words
A method according to claim 1 further comprising the step of embossing said heat-formed film prior to said leaching step.
Claim 2
Dependent Claim
20 words
heat-forming the ground mixture resulting from said step (1) under stress by extruding, calendering or pressing, to form a film,
Claim 3
Dependent Claim
43 words
heat treating said film under a pressure of less than 10 p.s.i. for a sufficient time and at a sufficient temperature to relieve strain patterns introduced into said film by the stress applied during said heat-forming, without causing degradation of said polyurethane, and
Claim 4
Dependent Claim
23 words
A method according to claim 2 wherein said heat-formed film, after said heat treatment, is superposed upon a nonwoven web and laminated thereto.
Claim 5
Dependent Claim
33 words
A method according to claim 3 wherein said heat-formed film is laminated to a backup interlayer prior to said superposing step, and said interlayer is laminated to said web after said superposing step.
Claim 6
Dependent Claim
9 words
leaching said particles from said heat-formed and heat-treated film.
Claim 7
Dependent Claim
85 words
A method according to claim 1 wherein: said storage shear modulus ranges from 0.5 to 2.5 X 108 dynes/cm2 at 23* C., said loss tangent determined under said conditions is less than 0.2, said particles are less than 15 microns in size and are present in said heat-formed film to the extent of about 30 to about 60 volume percent, and said heat treatment lasts less than 60 minutes and is carried out at an ambient temperature ranging from about 250* to about 500* F.
Claim 8
Dependent Claim
77 words
A method according to claim 1 wherein said heat-formed film further comprises an amount of an epoxidized glyceryl ester of a C5 - C24 carboxylic acid sufficient to ensure that said leached film, prior to any further processing will have an M.V.T. greater than 3,000 g./hr/100 percent m2, at 23* C. and a relative humidity increment of 100 percent on one side of said leached film and 50 percent on the other side of said leached film.
Claim 9
Dependent Claim
34 words
A method according to claim 6 wherein said epoxidized glyceryl ester is epoxidized soybean oil and said amount of said epoxidized glyceryl ester is 1-10 parts per hundred parts by weight of said polyurethane.
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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) | 1976-11-05 | 1977-05-07 | 1977-11-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-05 | 1981-05-07 | 1981-11-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-05 | 1985-05-07 | 1985-11-06 | $7700.00 | Window Closed / Lapsed |