Patent US3985934A successfully refreshed from Google Patents.
US3985934A
Expired / Lapsed
US
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Polyimide fiber having a serrated surface and a process of producing same
Assignee: Dow Chemical Co
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Filing: 1975-05-08
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Granted: 1976-10-12
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Expires: 1995-05-08
Abstract
Abstract High temperature resistant aromatic copolyimide fibers are disclosed together with processes for their preparation by wet and dry spinning techniques from solvent soluble copolyimides. The latter are prepared from benzophenone-3,3',4,4'-tetracarboxylic acid dianhydride and a mixture of 4,4'-methylenebis(phenyl isocyanate) and toluene diisocyanate (2,4-, or 2,6-isomer, or mixtures thereof). The wet spinning process can be stopped at any one of the stages taught, to yield useful fibers. The choice of coagulant fluid in the spin bath controls the fiber cross-section which in turn controls certain fiber characteristics. When glycerine or a low molecular weight aliphatic glycol is employed as coagulant fluid, the high temperature fiber obtained has advantageous properties which are otherwise difficult or impossible to obtain.
Inventors
- 👤 William J. Farrissey, Jr.
- 👤 Besir K. Onder
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 05:17
CPC Classifications
D; D01; D01F; D01F6/00; D01F6/78; D01D; D01D5/00; D01D5/253; Y; Y10; Y10T; Y10T428/00; Y10T428/29; Y10T428/2913; Y10T428/2933; Y10T428/2964; Y10T428/2967; Y10T428/2969; Y10T428/2973; Y10T428/2978
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
60 words
A filament characterized by a serrated and interrupted annular cross-section said filament comprising a copolyimide having the structure ##SPC6## wherein from 10 to 30 percent of said recurring units are those in which R represents ##SPC7## and the remainder of said units are those in which R represents a member selected from the group consisting of ##SPC8## and mixtures thereof.
Claim 2
Dependent Claim
60 words
A filament characterized by a serrated and interrupted annular cross-section said filament comprising a copolyimide having the structure ##SPC6## wherein from 10 to 30 percent of said recurring units are those in which R represents ##SPC7## and the remainder of said units are those in which R represents a member selected from the group consisting of ##SPC8## and mixtures thereof.
Claim 3
Dependent Claim
47 words
A filament according to claim 1 wherein 20 percent of said recurring units are those in which R represents ##SPC9## and the remaining 80 percent of said recurring units are those in which R represents a member selected from the group consisting of ##SPC10## and mixtures thereof.
Claim 4
Dependent Claim
246 words
A process for the production of copolyimide filaments characterized by a serrated and interrupted annular cross-section comprising the steps of: a. forming a copolyimide filament by spinning a dipolar aprotic solvent solution of a copolyimide having the structure ##SPC11## wherein from 10 to 30 percent of said recurring units are those in which R represents ##SPC12## and the remainder of said units are those in which R represents a member selected from the group consisting of ##SPC13## and mixtures thereof, directly into a coagulant bath comprising a member selected from the group consisting of lower monoalkylene glycols, lower dialkylene glycols, glycerine, and solutions thereof with water; b. passing said filament through at least one aqueous bath containing from about 0.5 percent to about 2.0 percent of a surfactant; c. removing at least 75 percent of the volatiles from said washed filament by passing it over at least one roller heated to a temperature from about 100° C to about 220° C while drawing it to a total draw ratio from about 1X to about 3X; d. drying said filament to remove the remaining volatiles; e. orienting said filament by drawing it over a surface heated from about 325° C to about 400° C to a draw ratio up to about 5X and; f. tempering said filament by passing it over a surface at a temperature at least as high as the orienting temperature, said surface being disposed between two rollers, and allowing the filament to relax.
Claim 5
Dependent Claim
246 words
A process for the production of copolyimide filaments characterized by a serrated and interrupted annular cross-section comprising the steps of: a. forming a copolyimide filament by spinning a dipolar aprotic solvent solution of a copolyimide having the structure ##SPC11## wherein from 10 to 30 percent of said recurring units are those in which R represents ##SPC12## and the remainder of said units are those in which R represents a member selected from the group consisting of ##SPC13## and mixtures thereof, directly into a coagulant bath comprising a member selected from the group consisting of lower monoalkylene glycols, lower dialkylene glycols, glycerine, and solutions thereof with water; b. passing said filament through at least one aqueous bath containing from about 0.5 percent to about 2.0 percent of a surfactant; c. removing at least 75 percent of the volatiles from said washed filament by passing it over at least one roller heated to a temperature from about 100° C to about 220° C while drawing it to a total draw ratio from about 1X to about 3X; d. drying said filament to remove the remaining volatiles; e. orienting said filament by drawing it over a surface heated from about 325° C to about 400° C to a draw ratio up to about 5X and; f. tempering said filament by passing it over a surface at a temperature at least as high as the orienting temperature, said surface being disposed between two rollers, and allowing the filament to relax.
Claim 6
Dependent Claim
51 words
The process according to claim 3 wherein the copolyimide has the structure ##SPC14## wherein 20 percent of said recurring units are those in which R represents ##SPC15## and the remainder of said units are those in which R represents a member selected from the group consisting of ##SPC16## and mixtures thereof.
Claim 7
Dependent Claim
13 words
The process according to claim 3 wherein the dipolar aprotic solvent is N-methylpyrrolidone.
Claim 8
Dependent Claim
33 words
The process according to claim 3 wherein said dipolar aprotic solvent solution of copolyimide employed as the spinning solution contains from about 10 percent to about 30 percent by weight of said copolyimide.
Claim 9
Dependent Claim
20 words
The process according to claim 3 wherein said surfactant employed in step (b) is a polyalkyleneoxy polydimethylsiloxane containing hydroxyl groups.
Claim 10
Dependent Claim
12 words
The process according to claim 3 wherein the coagulant bath comprises glycerine.
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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) | 1979-10-12 | 1980-04-12 | 1980-10-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-10-12 | 1984-04-12 | 1984-10-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-10-12 | 1988-04-12 | 1988-10-12 | $7700.00 | Window Closed / Lapsed |