Method for reducing the aliphatic halide content of epoxy resins using a solvent mixture including a polar aprotic solvent
AssigneeThe Dow Chemical Company
InventorsChun S. Wang, Zeng-Kun Liao
Life of this patent
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Abstract
The total halide content of epoxy resins is reduced by heating a resin containing undesirable halide dissolved in a solvent mixture containing at least one polar aprotic solvent in the presence of an alkali metal hydroxide for a time sufficient to reduce the total halide content.
Claims16
In a method for reducing the undesirable halide content of an epoxy resin containing hydrolyzable halide and/or bound halide which method consists essentially of heating said epoxy resin which has been dissolved in a solvent system containing a ketone, an aromatic hydrocarbon, or any combination thereof in the presence of a basic-acting compound at a temperature and for a time sufficient to reduce the total aliphatic halide content of said epoxy resin and thereafter recovering the resultant epoxy resin;
- the improvement which comprises employing as an additional solvent an organic polar aprotic solvent different from the aforementioned ketone or aromatic hydrocarbon in an amount of from about 2 to about 80 percent by weight of the total amount of solvent employed.
A process for reducing the total undesirable halide content of an epoxy resin containing hydrolyzable and/or bound halide which process consists essentially of
- (A) dissolving said epoxy resin in a solvent system which comprises
- (1) from about 2 to about 80 percent by weight of at least one organic polar aprotic solvent which is neither a ketone nor an aromatic hydrocarbon;
- (2) from about 20 to about 49 percent by weight of at least one ketone;
- and
- (3) from about 20 to about 49 percent by weight of at least one aromatic hydrocarbon;
- and;
- (B) heating the resultant solution to a temperature of from about 60.degree. C. up to about 150.degree. C.;
- (C) adding from about 0.25 to about 10 moles of a 10% to about 70% aqueous solution of an alkali metal hydroxide per equivalent of total halide;
- (D) continuing the heating for a time sufficient to reduce the total halide content of said epoxy resin;
- (E) washing the product from step (D) with either water, a dilute aqueous solution of a weak inorganic acid, acid salt or a combination thereof;
- and
- (F) recovering the resultant epoxy resin having a reduced total halide content from the product of step (E).
Dependencies are inferred from the claim text.