Foundry mold and core compositions

Claim 1

A REFRACTORY MOLD AND CORE COMPOSITION FOR THE FABRICATION OF FOUNDRY SHAPES WHICH COMPRISES A MAJOR AMOUNT OF FOUNDRY AGGREGATE COHERENTLY BONDED BY AN EFFECTIVE BONDING AMOUNT OF UP TO ABOUT 20 WEIGHT PERCENT OF A BINDER COMPOSITION CONSISTING ESSENTIALLY OF 10 TO 75 WEIGHT PERCENT COLLOIDAL SILICA UNIFORMLY DISPERSED IN A MATRIX OF 25 TO 90 WEIGHT PERCENT RSIO3/2 IN WHICH R IS SELECTED FROM THE GROUP CONSISTING OF ALKYL RADICALS OF 1 TO 3 CARBON ATOMS, THE VINYL RADICAL, THE 3,3,3-TRIFLUOROPROPYL RADICAL, THE GAMMA-GLYCIDOXYPROPYL RADICAL AND THE GAMMA-METHACRYLOXYPROPYL RADICAL, AT LEAST 70 WEIGHT PERCENT OF THE MATRIX BEING CH3SIO3/2.

Claim 6

A method of preparing molds and cores for the casting of metals comprising a. mixing a major amount of foundry aggregate with a binder composition consisting essentially of a dispersion of colloidal silica in a lower aliphatic alcohol-water solution of the partial condensate of a silanol of the formula RSi(OH)3 in which R is selected from the group consisting of alkyl radicals of 1 to 3 inclusive carbon atoms, the vinyl radical, the 3,3,3, -trifluoropropyl radical, the gamma-glycidoxypropyl radical and the gamma-methacryloxypropyl radical, at least 70 weight percent of the silanol being CH3Si(OH)3, said binder composition containing from 15 to 60 weight percent solids consisting essentially of 10 to 75 weight percent colloidal silica and 25 to 90 weight percent of the partial condensate, said composition containing sufficient acid to provide a pH in the range of 3.0 to 6.0; b. forming the mixture into the desired shape c. drying the shaped article to remove at least the major portion of the binder solvent, d. thereafter curing the partial condensate portion of the binder.

Claim 7

A method of preparing molds and cores for the casting of metals comprising a. mixing a major amount of foundry aggregate with a binder composition consisting essentially of a dispersion of colloidal silica in a lower aliphatic alcohol-water solution of the partial condensate of a silanol of the formula RSi(OH)3 in which R is selected from the group consisting of alkyl radicals of 1 to 3 inclusive carbon atoms, the vinyl radical, the 3,3,3, -trifluoropropyl radical, the gamma-glycidoxypropyl radical and the gamma-methacryloxypropyl radical, at least 70 weight percent of the silanol being CH3Si(OH)3, said binder composition containing from 15 to 60 weight percent solids consisting essentially of 10 to 75 weight percent colloidal silica and 25 to 90 weight percent of the partial condensate, said composition containing sufficient acid to provide a pH in the range of 3.0 to 6.0; b. forming the mixture into the desired shape c. drying the shaped article to remove at least the major portion of the binder solvent, d. thereafter curing the partial condensate portion of the binder.