Bisaminophenyl-based curatives and amidine-based curatives and cure accelerators for perfluoroelastomeric compositions
Novel monoamidine, monoamidoxime and bisamidine curatives, co-curatives and cure accelerators are provided for use with perfluoroelastomeric compositions as well as novel synthesis methods for making monoamidine- and monoamidoxime-based curatives, co-curatives and cure accelerators. Also provided are diphenyl-based curatives, co-curatives and cure accelerators having sufficiently high molecular weight such that the melting temperature of the curatives, co-curatives and cure accelerators is no greater than about 240° C., and more preferably no greater than about 230° C.
1. A method for making an amidine-based curative, comprising
(a) reacting an organic alkylacid with an alcohol to form an alkylester;
(b) reacting the alkyl ester with ammonia to form an alkylcarboxyamide;
(c) reacting the alkylcarboxyamide with dehydrating agent to form an alkyl nitrile; and
(d) reacting the alkyl nitrile with at least one of ammonia or an amine to form a curative, wherein the amidine-based curative is capable of curing or accelerating the cure of a perfluoroelastomeric composition.
2. The method according to claim 1 , wherein the perfluoroelastomeric composition comprises at least one cyano curesite monomer.
3. The method according to claim 1 , wherein the curative is perfluoroheptanamidine.
4. The method according to claim 1 , wherein the alkyl nitrile is added to an excess of the at least one of ammonia or amine.
5. The method according to claim 4 , wherein the at least one of ammonia or amine is liquid ammonia and the excess of the liquid ammonia is ten fold.
6. A method for making a bisaminophenol-based curative, comprising:
(a) reacting a perfluoroacyl fluoride with potassium fluoride to form a potassium alcoholate reaction product;
(b) reacting the potassium alcoholate reaction product with a perfluoroallylfluorosulfate to form a perfluoroallyl ether;
(c) reacting the perfluoroallyl ether with an oxidizing agent to form a perfluoroglycidyl ether;
(d) reacting the perfluoroglycidyl ether with aluminum chloride in a fluorinated solvent to isomerize an epoxide group on the perfluoroglycidyl ether to a ketone;
(e) reacting the ketone group with phenol in the presence of hydrogen fluoride to form a bisphenol-based compound;
(f) nitration of the bisphenol-based compound to give a bisnitrophenol-based compound; and
(g) reduction of the bisnitrophenol-based compound to form a bisaminophenol-based curative, wherein the bisaminophenol-based curative is capable of curing a perfluoroelastomeric composition.
7. The method according to claim 6 , wherein the perfluoroelastomeric composition comprises at least one cyano curesite monomer.
8. The method according to claim 6 , wherein the bisaminophenol based curative is a substituted bisaminophenyl-based curative which has formula (III):
wherein Z is an amino, sulthydryl, or hydroxyl group; and A is selected from the group consisting of unsubstituted and substituted and branched and straight chain carbon-based groups, wherein the carbon-based groups are selected from the group consisting of perfluoroalkyl and perfluoralkoxy groups of from 1 to about 22 carbon atoms.
9. The method according to claim 8 , wherein A comprises from 3 to 10 carbon atoms.