Claims
- 1. A process for preparing an isoimide-containing oligomer which comprises:
- (a) reacting in a first chosen organic solvent with the addition of heat
- (1) the reaction product of
- (i) a carboxylic acid dianhydride having the formula, ##STR38## wherein R is a tetravalent organic group containing 2 to 27 carbon atoms, and
- (ii) a diamine having the formula H.sub.2 N--R.sub.5 --NH.sub.2 wherein R.sub.5 is a divalent aryl group containing 2 to 30 carbon atoms; with a compound to enable formation of a polyamic acid and which compound is selected from the group consisting of:
- (2) a functional amine having the formula H.sub.2 N--R.sub.1 --X wherein R.sub.1 is a divalent organic group containing 1 to 20 carbon atoms, and
- (3) a monoanhydride having the formula ##STR39## wherein R.sub.7 is a trivalent aryl group having substituted thereon X, a radical containing an alkenylene group, or a heterocyclic group, and X in (2) and (3) is a radical having an unsaturated functional group capable of undergoing addition polymerization with another radical having an unsaturated functional group;
- (b) cooling the resulting first reaction mixture to a selected temperature about at least as low as ambient temperature,
- (c) adding to said first reaction mixture at said selected temperature a dehydrating agent to cyclize said polyamic acid by dehydration to thereby form an isoimide-containing oligomer in solution in a second reaction mixture, and which dehydrating agent has the following properties of (1) being readily soluble with a polyamic acid in a common solvent, (2) cyclizing a polyamic acid at reduced temperatures at least as low as ambient temperature, (3) not substantially adversely affecting solubility of any reactants in the presence of the polyamic acid and permitting all of the necessary reactants to remain in solution, (4) not causing generation of a substantial amount of undesirable side-reaction products which are not readily removable and which might or do adversely affect the isoimide oligomer thus produced, and (5) not substantially adversely affecting a polyimide produced therefrom,
- (d) mixing the solution of said second reaction mixture with a second selected solvent to produce precipitation of said isoimide-containing oligomer as a solid product; and
- (e) separating said solid product from said second selected solvent.
- 2. The process of claim 1 wherein the unsaturated functional groups on the amine containing compound are vinyl groups, cyano groups, acetylenic groups, and ethylenic groups.
- 3. The process of claim 1 wherein the reaction mixture is further reduced to a temperature within a range of 0.degree. C. to about 5.degree. C. to cause reduction of further undesirable side-reaction products.
- 4. The process of claim 1, wherein said dehydrating agent is selected from the group consisting of trifluoroacetic anhydride and N,N-dicyclohexylcarbodiimide and said selected temperature is within the range of about 0.degree. C. to about 20.degree. C.
- 5. The process of claim 1 wherein said first chosen organic solvent is selected so that it has the following properties of (1) having a low boiling temperature of at least below 120.degree. C., (2) having a high solubility factor so that both the polyamic acid and the cyclizing agent are readily and quickly solubilized in the solvent, (3) having a solubility characteristic so that the oligomer produced by the cyclization of the polyamic acid is also readily soluble therein, (4) having minimum reactivity with the oligomer thus formed, (5) being sufficiently insoluble to any undesirable by-products which may be formed, (6) having substantially no strong hydrogen bond interaction with the oligomer thus formed, (7) presenting substantially no toxicity to the reactants or the oligomer thus formed, and (8) and not causing reversion of isoimide to imide.
- 6. The process as defined in claim 1 wherein the dianhydride is benzophenonetetracarboxylic dianhydride.
- 7. The process as defined in claim 1 wherein the functional amine is 3-aminophenyl acetylene.
- 8. The process as defined in claim 1 wherein the dehydrating agent is N,N-dicyclohexylcarbodiimide.
- 9. The process as defined in claim 1 wherein the diamine is 1,3-di-(3-aminophenoxy) benzene.
- 10. The process as defined in claim 1 wherein the diamine is 4,4'-oxydianiline.
- 11. The process as defined in claim 1 wherein X is a vinyl, acetylene or cyano group.
- 12. The process defined in claim 1, wherein the dianhydride has the formula: ##STR40## wherein Y is selected from the group consisting of ##STR41## --(CH.sub.2).sub.x, --C(CH.sub.3).sub.2 --, --O--, --S--, --SO.sub.2 --, --C(CF.sub.3).sub.2 --, --(CF.sub.2).sub.x -- wherein x is an integer from 1 to 5, and a group having the formula: ##STR42## wherein R.sub.2 and R.sub.3 are each selected from the group consisting of aryl and alkyl.
- 13. The process as defined in claim 1 wherein X is selected from the group consisting of a group of the formula:
- --C.tbd.CH
- --CH.dbd.CH.sub.2 ##STR43## wherein R.sub.4 is H or --CH.sub.3, and --CN.
- 14. The process as defined in claim 1 wherein the monoanhydride is maleic anhydride.
- 15. The process as defined in claim 1 wherein the monoanhydride has the formula: ##STR44## wherein R.sub.8, R.sub.9 and R.sub.10 are the same or different and are each selected from the group consisting of H or lower alkyl.
- 16. A process for preparing acetylene-terminated isoimide oligomers essentially free of impurities which comprises:
- (a) reacting an aromatic dianhydride, an aromatic diamine and an amino aromatic acetylene in a first chosen solvent to produce a polyamic acid,
- (b) reacting said polyamic acid with a cyclization agent selected from the group consisting of trifluoroacetic anhydride and N,N-dicylohexylcarbodiimide at a temperature at least as low as ambient temperature to cause cyclization of said polyamic acid and produce a reaction mixture containing said acetylene-terminated isoimide oligomer in solution and essentially free of said impurities,
- (c) mixing the solution of said reaction mixture with a second solvent to produce precipitation of said isoimide oligomer as a solid product; and
- (d) separating said solid product from said second solvent.
- 17. The process as defined in claim 16, said first solvent being selected from the class consisting of tetrahydrofuran and dioxane.
- 18. The process as defined in claim 16, said temperature ranging from about 20.degree. C. to about 0.degree. C.
- 19. The process as defined in claim 16, wherein said second solvent comprises a hexane compound.
- 20. The process as defined in claim 16, said reaction between said aromatic dianhydride, said aromatic diamine and said amino aromatic acetylene taking place at approximately reflux temperature.
- 21. A process for preparing acetylene-terminated isoimide oligomers essentially free of impurities which comprises the steps of:
- (a) heating a solution of an aromatic dianhydride and an aromatic diamine in a first chosen organic solvent to produce a first reaction mixture,
- (b) adding an amino aromatic acetylene to said first reaction mixture and heating the resulting second reaction mixture to produce the corresponding polyamic acid,
- (c) cooling said second reaction mixture to a selected temperature at least as low as ambient temperature,
- (d) adding a dehydrating agent selected from the group consisting of trifluoroacetic anhydride and N,N-dicyclohexylcarbodiimide to said second reaction mixture at said selected temperature to cause cyclization of said polyamic acid and to produce a third reaction mixture containing said acetylene-terminated isoimide oligomer in solution, without formation of side-reaction products,
- (e) mixing with the solution of said third reaction mixture a second solvent to produce precipitation of said oligomer as a solid product, and
- (f) separating said solid product from said second solvent.
- 22. The process as defined in claim 21, said heating in steps (a) and (b) taking place at about reflux temperature, and the reaction with said dehydrating agent in step (d) taking place at between about 20.degree. C. and 0.degree. C.
- 23. The process as defined in claim 21, said first chosen solvent being selected from the class consisting of tetrahydrofuran and dioxane.
- 24. The process as defined in claim 21, wherein said second solvent is selected from the class consisting of isopropyl alcohol and hexane.
- 25. The process as defined in claim 21, said aromatic dianhydride being a benzophenonetetracarboxylic dianhydride, said aromatic diamine being di(aminophenoxy)benzene and said amino aromatic acetylene being an aminophenylacetylene.
- 26. The process as defined in claim 21, said aromatic dianhydride being employed in a proportion ranging from about 1.1 to about 2.5 moles and said amino aromatic acetylene in a proportion ranging from about 2.2 to about 0.12 moles, per mole of said aromatic diamine, and said dehydrating agent in a proportion from about 2.0 to about 2.3 moles, per mole of aromatic dianhydride.
- 27. The process as defined in claim 21, said aromatic dianhydride being pyromellitic dianhydride, said aromatic diamine being 2,2-bis[4-aminophenoxy)phenyl]-hexafluoropropane and said aromatic acetylene being an aminophenyl acetylene.
- 28. The process as defined in claim 21, said aromatic dianhydride being a benzophenonetetracarboxylic dianhydride, said aromatic diamine being 2,2-bis[4-(4-aminophenoxy)phenyl]-hexafluoropropane and said aromatic acetylene being an aminophenylacetylene.
- 29. A process for preparing acetylene-terminated isoimide oligomers essentially free of impurities which comprises the steps of:
- (a) heating a solution of benzophenonetetracarboxylic dianhydride and a first solvent selected from the class consisting of (1) di(aminophenoxy)benzene in tetrahydrofuran, (2) tetrahydrofuran, and (3) dioxane, under reflux to produce a first reaction mixture,
- (b) adding an aminophenylacetylene to said first reaction mixture and heating the resulting second reaction mixture under reflux to produce the corresponding polyamic acid,
- (c) cooling said second reaction mixture to a selected temperature within the range of about 0.degree. C. to about 20.degree. C.,
- (d) adding a dehydrating agent selected from the group consisting of trifluoroacetic anhydride and N,N-dicyclohexylcarbodiimide to said second reaction mixture at said selected temperature to cause cyclization of said polyamic acid and to produce a third reaction mixture containing said acetylene-terminated oligomer,
- (e) filtering said third reaction mixture to remove any side-reaction products which are insoluble in said first solvent, to thereby form a filtrate containing said isoimide oligomer,
- (f) pouring said filtrate into a second precipitating solvent selected from (1) a mixture of hexanes and (2) isopropyl alcohol, and precipitating said oligomer,
- (g) separating said oligomer from said precipitating solvent,
- (h) washing said oligomer with a third solvent, and
- (i) drying said oligomer to recover an isoimide oligomer product essentially free of impurities.
- 30. The process as defined in claim 29, said benzophenone tetracarboxylic dianhydride being 3,3',4,4'-benzophenonetetracarboxylic dianhydride, said di(aminophenoxy)-benzene being 1,3-di(3-aminophenoxy)-benzene, and said aminophenylacetylene being 3-aminophenylacetylene.
- 31. The process as defined in claim 30, said dehydrating agent being N,N-dicyclohexylcarbodiimide.
- 32. The process as defined in claim 1 said first solvent being selected from the class consisting of tetrahydrofuran and dioxane.
RELATED APPLICATION
This application is a continuation-in-part of U.S. patent application Ser. No. 206,317, filed July 24, 1981, entitled "Isoimide Containing Oligomers", now U.S. Pat. No. 4,438,273.
US Referenced Citations (5)
Continuation in Parts (1)
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Number |
Date |
Country |
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206317 |
Jul 1981 |
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