초록

Catalysts for hardening aqueous alkali metal silicate solutions comprising mixtures of alkylene carbonate and methyl esters of organic acids are disclosed. The hardening catalysts are primarily useful in the production of high quality foundry molds and cores based on alkali metal silicate binders.

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A composition of matter for hardening aqueous alkali metal silicate solutions consisting essentially of a mixture of an alkylene carbonate having 2 to 10 carbon atoms in the alkylene radical and a methyl ester of an organic acid which is selected from the group consisting of a methylester of a monoc

A composition of matter for hardening aqueous alkali metal silicate solutions consisting essentially of a mixture of an alkylene carbonate having 2 to 10 carbon atoms in the alkylene radical and a methyl ester of an organic acid which is selected from the group consisting of a methylester of a monocarboxylic acid containing 1 to 6 carbon atoms and a dimethylester of a dicarboxylic acid containing 3 to 10 carbon atoms, in a weight ratio of 4 to 30 parts by weight of ester to 70 to 96 parts by weight of carbonate. In a method for producing foundry molds and foundry cores, comprising mixing sand, an aqueous solution of an alkali metal silicate, and a hardening catalyst, the improvement comprising including in the mixture, as said hardening catalyst, a sufficient quantity of a mixture of an alkylene carbonate having 2 to 10 carbon atoms in the alkylene radical and a methyl ester of an organic acid which is selected from the group consisting of a methylester of a monocarboxylic acid containing 1 to 6 carbon atoms and a dimethylester of a dicarboxylic acid containing 3 to 10 carbon atoms, in a weight ratio of 4 to 30 parts by weight of ester to 70 to 96 parts by weight of carbonate, and then shaping the mix and allowing the shaped mix to set.