Surfactant free dispersing agent

Process for producing a surfactant free, low molecular weight copolymer, comprising the steps of:

• polymerizing a composition comprising
• (i) at least one ethylenically unsaturated monomer having acidic functionality and being present in an amount of 95-75% by weight, based on the total amount of monomers in said composition, and
• (ii) at least one ethylenically unsaturated monomer having no acidic functionality and being present in an amount of 5-25% by weight, based on the total amount of monomers in said composition,
• in only water as polymerization reaction medium
• in the presence of a redox system of a hydroperoxide and a hydroxylammonium salt as polymerization initiator
• at atmospheric pressure and
• at a temperature in the range of 80° C. to 100° C.
• without use of a surfactant,
• and subsequently, after polymerization, neutralizing the reaction mixture by means of an alkali,
• thereby obtaining a surfactant free copolymer with a K value molecular weight in the range of 10 to 100, preferably 20 to 60, more preferably, 25 to 40,
• wherein the K value molecular weight is determined as described in the description,
• wherein the ethylenically unsaturated monomer having acidic functionality is selected from acrylic acid (AA), methacrylic acid (MAA), 2-acrylamido-2-methylpropane sulfonic acid (AMPS), or sodium vinylsulfonate (SVS), and the ethylenically unsaturated monomer having no acidic functionality is selected from butyl acrylate (BA), methyl methacrylate (MMA), ethyl acrylate (EA), 2-ethylhexyl acrylate or vinyl acetate (VAM).