Patent ID: 8919421

Claim:
A method for producing cores and moulds for the foundry industry, comprising: providing a flowable, fire-resistant primary moulding material; applying an acid to the flowable, fire-resistant primary moulding material, to obtain an acid-coated primary moulding material; applying a binder that is curable with an acid to the acid coated fire-resistant primary moulding material, to obtain a fire-resistant primary moulding material coated with a binder; shaping the fire-resistant primary moulding material coated with a binder to form a moulded body; and curing the moulded body; wherein the acid is a mixture of methane sulfonic acid and at least one further, sulphur-free acid, wherein the fraction of methane sulfonic acid in the acid is selected to be less than 70% by weight, the sulphur-free acid is an organic acid having a carboxyl group and at least one more group selected from the group consisting of carboxyl group, hydroxy group, and aldehyde group, and the organic acid has a pK a of less than 4, measured at 25° C., and the acid-binder comprises a furan-no-bake binder or a phenol-no-bake binder.