FREE RADICAL INITIATOR COMPOSITIONS CONTAINING T-BUTYL HYDROPEROXIDE AND THEIR USE
A composition comprising (a) an epoxy resin; and (b) a hydroperoxide composition comprising a t-butyl hydroperoxide solution that contains no more than 7 weight percent water, and use of the compositions to prepare foundry shapes, the foundry shapes prepared by the process, the use of the foundry shapes to prepare cast metal articles, and the cast metal articles prepared by the process.
1 . An epoxy composition comprising:
an epoxy resin; and
a free radical initiator composition comprising a t-butyl hydroperoxide solution containing water in an amount of less than 7 weight percent.
2 . The epoxy composition of claim 1 , further comprising:
cumene hydroperoxide in the free radical initiator composition.
3 . The epoxy composition of claim 2 , wherein:
the weight ratio of t-butyl hydroperoxide to cumene hydroperoxide is from 20 to 1 to 1 to 20.
4 . The composition of claim 3 , wherein
the amount of free radical initiator composition is from 10 to 30 parts by weight based upon 100 parts by weight of total composition.
5 . A foundry binder comprising:
20 to 70 parts by weight of an epoxy resin;
0 to 50 parts by weight of an acrylate;
0 to 30 parts by weight of an alkyl ester of a fatty acid, wherein the alkyl group of the ester is an aliphatic hydrocarbon having up to 8 carbon atoms, preferably butyl tallate; and
an effective free radical initiating amount of the free radical initiator composition of claim 1 ,
wherein the epoxy resin, acrylate, alkyl ester and free radical initiator are separate components or, if mixed, the free radical initiator is separate from the acrylate; and
wherein the parts by weight are based upon 100 parts of binder.
6 . A process for preparing a foundry shape, comprising the steps of:
introducing, into a pattern to form a foundry shape, a foundry mix comprising from about 90 to about 99 parts by weight of a foundry aggregate, with the balance comprising a foundry binder comprising, based on parts by weight of the foundry binder:
20 to 70 parts of an epoxy resin;
0 to 50 parts of an acrylate;
0 to 30 parts of an alkyl ester of a fatty acid, wherein the alkyl group of the ester is an aliphatic hydrocarbon having up to 8 carbon atoms; and
an effective amount of a free radical initiator comprising at least one of: t-butyl hydroperoxide and cumene hydroperoxide; and
curing the formed shape with gaseous sulfur dioxide.
7 . The process of claim 6 , wherein:
the gaseous sulfur dioxide used for the curing step is diluted with nitrogen, such that the concentration of sulfur dioxide is as low as 25% based on the volume of the inert carrier gas.
8 . The process of claim 6 wherein:
the gaseous sulfur dioxide used for the curing step is diluted with nitrogen, such that the concentration of sulfur dioxide is as low as 5% based on the volume of the inert carrier gas.
9 . A foundry shape prepared by the method of claim 7 .
10 . A process of casting a metal article, comprising the steps of:
fabricating a foundry shape according to claim 7 ;
pouring a molten metal into the foundry shape;
allowing the poured molten metal to cool and solidify in the foundry shape, forming a cast article; and
separating the cast article from the foundry shape.
11 . The process of claim 10 , wherein:
the metal is aluminum.
12 . A metal casting produced by the process of claim 10 .
13 . The process of claim 6 , wherein:
the alkyl ester of a fatty acid is butyl tallate.