US5126085A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for preparing polyimide sheet molding compound
Assignee: Dexter Composites Inc
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Filing: 1990-12-07
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Granted: 1992-06-30
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Expires: 2010-12-07
Abstract
Abstract A process for making polyimide sheet molding compounds which involves the preparation of a polyimide precursor solution of adjusted viscosity that includes a mixture of high and low boiling alcohols, and which also includes monomeric reactants including a diester of an aromatic dianhydride, an aromatic diamine, a monoester of norbornene dianhydride, the reactants being present in a relative molar ratio selected to yield a polyimide having a desired molecular weight. The solution, which further contains particular amounts of staple reinforcing fibers is deposited as a sheet between two carrier film layers and is partially dried to remove the low boiling alcohols. The molecular weight of the polyimide and the amount of any insoluble components present in the solution are controlled so that when the sheet molding compound is imidized under particular heating conditions, its melt viscosity will allow the melted polyimide to retain the staple fibers present therein uniformly distributed throughout the melt as it flows throughout molds into which the sheet molding compounds are placed.
Inventors
- 👤 John D. Thorp
- 👤 Joseph P. Reardon
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 11:34
CPC Classifications
C; C08; C08G; C08G73/00; C08G73/06; C08G73/10; C08G73/1003; C08G73/1007; C08G73/101; C08J; C08J5/00; C08J5/24; C08J5/241; C08J5/243; C08J2379/00; C08J2379/04; C08J2379/08
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
108 words
A process for preparing thermosetting polyimide sheet molding compounds comprising: preparing a monomer solution from monomeric reactants comprising a diester of an aromatic dianhydride, an aromatic diamine, and a monoester of norbornene anhydride together with a mixture of alcohols, at least one of said alcohols having from 1 to 2 carbon atoms, and at least one of said alcohols having 4 to 6 carbon atoms; combining said monomer solution having a viscosity of from about 400 to about 2000 centipoise with staple filamentary material to form a polymerizable blend, and removing at least part of said alcohols having from 1 to 2 carbon atoms from said polymerizable blend.
Claim 2
Dependent Claim
108 words
A process for preparing thermosetting polyimide sheet molding compounds comprising: preparing a monomer solution from monomeric reactants comprising a diester of an aromatic dianhydride, an aromatic diamine, and a monoester of norbornene anhydride together with a mixture of alcohols, at least one of said alcohols having from 1 to 2 carbon atoms, and at least one of said alcohols having 4 to 6 carbon atoms; combining said monomer solution having a viscosity of from about 400 to about 2000 centipoise with staple filamentary material to form a polymerizable blend, and removing at least part of said alcohols having from 1 to 2 carbon atoms from said polymerizable blend.
Claim 3
Dependent Claim
28 words
A process according to claim 1 in which said monomeric reactants comprise (a) a diester of 3,3',4,4'-benzophenone tetracarboxylic dianhydride, (b) 4,4'-methylenedianiline, and (c) a monoester of 5-norbornene-2,3-dicarboxylic anhydride.
Claim 4
Dependent Claim
13 words
A process according to claim 2 in which said esters are methyl esters.
Claim 5
Dependent Claim
22 words
A process according to claim 2 in which reactants (a), (b), and (c) are present in the molar ratio of approximately 2:3:2.
Claim 6
Dependent Claim
52 words
A process according to claim 1 in which said alcohol mixture is a mixture of at least one alcohol selected from a first group of alcohols consisting of methyl and ethyl alcohol, and at least one alcohol selected from a second group of alcohols consisting of hexyl, butyl, amyl and pentyl alcohol.
Claim 7
Dependent Claim
29 words
A process according to claim 5 in which said filamentary material is in the form of staple fibers selected from the group consisting of glass fibers and carbon fibers.
Claim 8
Dependent Claim
13 words
A process according to claim 6 in which said fibers are glass fibers.
Claim 9
Dependent Claim
52 words
A process according to claim 6 in which said sheet molding compound is formed into a desired shape and heated until a polyimide is formed having a formulated molecular weight of from about 1,400 to about 1,600, said polyimide then being further heated until cross-linking occurs, thereby forming a fiber-reinforced composite structure.
Claim 10
Dependent Claim
23 words
A process according to claim 8 in which the cross-linked polyimide contains from about 42% to about 60%, by volume, of said fibers.
Claim 11
Dependent Claim
150 words
A process for preparing a thermosetting polyimide sheet molding compound comprising: preparing a monomer solution from monomeric reactants including a diester of an aromatic dianhydride, an aromatic diamine, and a monoester of norbornene anhydride together with a mixture of alcohols, at least one of said alcohols having from 1 to 2 carbon atoms, and at least one of said alcohols having from 4 to 6 carbon atoms, said monomer solution having a viscosity of from about 400 centipoise to about 2,000 centipoise; combining said monomer solution with staple fibers to form a polymerizable blend and placing said blend between two layers of a carrier film as a sheet, and heating said sheet to a temperature at which at least part of said alcohols having from 1 to 2 carbon atoms are removed, but at which at least part of said alcohols having from 4 to 6 carbon atoms are retained.
Claim 12
Dependent Claim
150 words
A process for preparing a thermosetting polyimide sheet molding compound comprising: preparing a monomer solution from monomeric reactants including a diester of an aromatic dianhydride, an aromatic diamine, and a monoester of norbornene anhydride together with a mixture of alcohols, at least one of said alcohols having from 1 to 2 carbon atoms, and at least one of said alcohols having from 4 to 6 carbon atoms, said monomer solution having a viscosity of from about 400 centipoise to about 2,000 centipoise; combining said monomer solution with staple fibers to form a polymerizable blend and placing said blend between two layers of a carrier film as a sheet, and heating said sheet to a temperature at which at least part of said alcohols having from 1 to 2 carbon atoms are removed, but at which at least part of said alcohols having from 4 to 6 carbon atoms are retained.
Claim 13
Dependent Claim
35 words
A process according to claim 10 which said monomeric reactants comprise a diester of 3,3',4,4'-benzophenone tetracarboxylic dianhydride; 4,4'-methylenedianiline; and a monoester of 5-norbornene-2,3-dicarboxylic anhydride, said reactants being present in the molar ratio of approximately 2:3:2.
Claim 14
Dependent Claim
13 words
A process according to claim 11 in which said fibers are glass fibers.
Claim 15
Dependent Claim
49 words
A process according to claim 12 in which said sheet molding compound is subsequently formed into a desired shape and heated to produce imidization and cross-linking, thereby providing a reinforced composite structure in which the cross-linked material contains from about 42% to about 60%, by volume, of said fibers.
Claim 16
Dependent Claim
29 words
A process according to claim 13 in which the polyimide thus formed has a melt viscosity of from about 10 2 poise to about 10 5 poise before cross-linking.
References Cited (Backward Citations)
US3654227A
Cited
US3528950A
Cited
US3573132A
Cited
US3745149A
Cited
US4141929A
Cited
US4568505A
Cited
US4302575A
Cited
US4880584A
Cited
US4765942A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-06-30 | 1995-12-30 | 1996-06-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-06-30 | 1999-12-30 | 2000-06-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-06-30 | 2003-12-30 | 2004-06-30 | $7700.00 | Window Closed / Lapsed |