Process for the preparation of dispersing agents in a solid form and their use in mineral binding compositions

A process for producing a dispersant in solid form, wherein the dispersant comprises at least 90% by weight in each case based on the total weight of dispersant, of at least one copolymer CP, wherein the copolymers CP comprise the following constituents:

• (i) repeat units A of general structure (I),
• and
• (ii) repeat units B of general structure (II),
• where
• each Ru is independently hydrogen or a methyl group,
• each Rv is independently hydrogen or COOM, where M is independently H, an alkali metal, or an alkaline earth metal,
• m=0, 1, 2 or 3,
• p=0 or 1,
• each R1 is independently —[YO]n—R4, where Y is a C2 to C4 alkylene and R4 is H, C1 to C20 alkyl, cyclohexyl or alkylaryl, and n=2-350, and
• the repeat units A and B in the copolymer CP have a molar ratio
• A:B within a range from 10:90 to 90:10,
• wherein the process comprises the following steps:
• a) producing a mixture of at least one copolymer CP, at least one base, and water, wherein the molar ratio of base to copolymer CP is selected such that a degree of neutralization of at least 55%, results,
• b) optionally drying the neutralized aqueous preparation from step a), and
• c) optionally comminuting the material obtained in step b).