BINDER FOR FOUNDRY SANDS

1. Use of binders based on plastics containing carboxyl groups for preparing thermosetting moulding sand foundry use, characterized in that the binders are an aqueous dispersion of a copolymer P synthesised from A) at least one unsaturated carboxylic acid of formula I see diagramm : EP0119468,P12,F1 wherein R1 , R2 and R3 represent hydrogen, an alkyl group with 1 to 6 carbon atoms or a group -(CH2 )n -COOM, whilst M represents a proton or an ammonium, alkali or alkaline earth metal cation and n represents zero or one, with the proviso that the unsaturated carboxylic acids of formula I have no more than two -COOM groups in the molecule, ijn amounts of at least 20 and at most 90 % by weight, based on all the copolymer P, and B) monomers which copolymerise with A) in amounts of from 10 to 80 % by weight, based on P, with the proviso that the percentage of groups -COOM wherein M represents an ammonium, alkali or alkaline earth metal cation, should not exceed 20 % of all the groups -COOM is the copolymer P, as monomers.