Binder, and the use thereof for the production of foundry moulds

A process for the preparation of foundry forms comprising the steps of: a) preparing a binder composition constituted by an aqueous solution of aluminum borophosphate curable by mixing with an alkaline earth oxide, with a boron content of up to 40 mol percent calculated on aluminum, where the molar ratio of phosphorus to aluminum and boron is around 2: 1 to 4: 1 and where the alkaline-earth material containing an alkaline earth oxide represents about 5-50% of the total weight of the oxide and phosphate, whose preparation consists of adding granulated boric acid on 85% phosphoric acid, with gentle agitation; add hydrated alumina to the stirred dispersion; heat the reaction mass to a temperature of about 110-120º f (43-49º c), remove the external heat source and continue the exothermic reaction for some time until reaching a maximum temperature of about 220-250º f. (104-110º c); apply again an external heat source up to a maximum temperature of 245-250º f (118-121º c); maintain this temperature until the reaction is complete; cool the reaction mass to about 200º f (93º c) and add water slowly with stirring; B) adding to said binder composition a normally solid compound which contains as a part of its chemical structure a group of general formula: Oh oh - c - c - Wherein the compound contains from 1 to 10 carbon atoms per hydroxy group and wherein 1 or 2 carbon atoms may be attached to a carbonyl oxygen; C) apply the binder composition and the additive to a sand to which an alkaline-earth hardening material containing an alkaline earth metal and an oxide has been applied D) configure the combination in appropriate castings and allow to harden. (Machine-translation by Google Translate, not legally binding)