US4405550A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Manufacture of polyimide film by solvent casting
Assignee: Mobil Oil AS
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Filing: 1981-04-17
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Granted: 1983-09-20
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Expires: 2001-04-17
Abstract
Abstract Polyimide film is manufactured by solvent casting onto a film-supporting surface. A solution of polyimide resin is dissolved in hot organic solvent to provide a casting dope. The film is coagulated by contacting an aqueous medium, substantially replacing the organic solvent in the film with water. Orienting the water-containing film and drying the oriented film to remove water produces a substantially homogeneous polyimide film having high electrical resistance, flexibility and strength.
Inventors
- 👤 Gordon P. Hungerford
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 23:50
CPC Classifications
B; B29; B29C; B29C41/00; B29C41/24; B29C41/26; B29C55/00; B29C55/02; B29C55/10; B29C55/12; B29C55/14; B29C55/143; C; C08; C08J; C08J5/00; C08J5/18; B29K; B29K2079/00; B29K2079/08; C08J2379/00; C08J2379/04; C08J2379/08
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
111 words
A method for making optically clear oriented polyimide film comprising: (a) applying onto a film supporting cooled surface a hot concentrated solution of polyimide in a polar aprotic organic solvent to provide a film comprising said polymer and said solvent; (b) comparatively slowly coagulating the polymer by contacting said film with an aqueous medium containing a major amount of organic solvent and a minor amount of water; (c) at least substantially replacing the solvent in said film with water; (d) machine direction orienting said water-containing film; and (e) transverse direction orienting said water-containing film; and (f) drying the biaxially oriented film while under constraint to remove at least substantially all water.
Claim 2
Independent Claim
111 words
A method for making optically clear oriented polyimide film comprising: (a) applying onto a film supporting cooled surface a hot concentrated solution of polyimide in a polar aprotic organic solvent to provide a film comprising said polymer and said solvent; (b) comparatively slowly coagulating the polymer by contacting said film with an aqueous medium containing a major amount of organic solvent and a minor amount of water; (c) at least substantially replacing the solvent in said film with water; (d) machine direction orienting said water-containing film; and (e) transverse direction orienting said water-containing film; and (f) drying the biaxially oriented film while under constraint to remove at least substantially all water.
Claim 3
Dependent Claim
38 words
The method of claim 1 wherein said aprotic solvent comprises one or more low molecular weight N-alkyl-2-pyrrolidones, pyridines, sulfoxides, sulfones, N,N-dialkyl-carboxamides; wherein said polyimide solution comprises a hot dope containing at least about 45 wt. % polyimide resin.
Claim 4
Dependent Claim
33 words
The method of claim 2 further comprising the step of passing the coagulated film through an aqueous medium having increasing water content and decreasing organic solvent content in the direction of film transport.
Claim 5
Dependent Claim
36 words
The method of claim 3 wherein said film is transported through a body of aqueous medium moving countercurrently to the film, said film being finally contacted with wash water to remove substantially all organic solvents therefrom.
Claim 6
Dependent Claim
13 words
The method of claim 3 wherein said aprotic solvent consists essentially of N-methyl-2-pyrrolidones.
Claim 7
Dependent Claim
27 words
The method of claim 5 wherein said aqueous medium initially contacting said film is maintained at an organic solvent content of at least about 95 weight percent.
Claim 8
Dependent Claim
25 words
The method of claim 1 wherein the polyimide contains a major portion of repeating units containing the moiety: ##STR3## where R is an organic residue.
Claim 9
Dependent Claim
26 words
The method of claim 1 wherein the polyimide resin comprises the reaction product of at least one aromatic polycarboxylic acid anhydride with aromatic polyisocyanate or polyamine.
Claim 10
Dependent Claim
22 words
The method of claim 8 wherein the anhydride consists essentially of pyromelletic dianhydride, benzophenone-3,3',4,4'-tetracarboxylic acid dianhydride or mixtures thereof with one another.
Claim 11
Dependent Claim
41 words
The method of claim 1 wherein said polyimide comprises the polymeric reaction product of at least one aromatic polycarboxylic anhydride and at least one polyisocyanate and wherein said resin solution contains up to about 40 weight percent of aprotic polar solvent.
Claim 12
Dependent Claim
15 words
The method of claim 2 wherein said aprotic polar solvent consists essentially of dimethyl sulfoxide.
Claim 13
Dependent Claim
14 words
The method of claim 2 wherein said aprotic polar solvent consists essentially of N-methyl-2-pyrrolidone.
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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) | 1986-09-19 | 1987-03-21 | 1987-09-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-09-19 | 1991-03-21 | 1991-09-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-09-19 | 1995-03-21 | 1995-09-20 | $7700.00 | Window Closed / Lapsed |