Synthesis and application of a polyacrylate dispersant on the preparation of ultrafine ground calcium carbonate in a laboratory stirred media mill

Free radical polymerization was used to prepare a series of P(AA/AMPS) polymers using acrylic acid (AA) and 2-acrylamido-2-methyl propane sulfonic acid (AMPS) as monomers, ammonium persulfate as the initiator, and isopropanol as the chain transfer agent. The effects of the AA/AMPS and isopropanol/water weight ratios, the initiator dosage, the reaction time, and the reaction temperature on the properties and the grinding effect of P(AA/AMPS) were investigated. The following optimal synthetic conditions were determined: an AA/AMPS weight ratio of 4, an isopropanol/water weight ratio of 1.25, an initiator dosage of 4 wt.% (based on the total monomer weight), a reaction time of 5.5 h, and a reaction temperature of 75 °C. The products were characterized by Fourier transform infrared (FT-IR) spectroscopy, liquid gel permeation chromatography (GPC) and thermogravimetric analysis (TGA). When the synthetic grinding dispersant was used in the ultrafine wet grinding of GCC, the fluidity of the GCC slurry was remarkably enhanced. P(AA/AMPS) prepared under optimal synthetic conditions was used in the ultrafine wet grinding process to investigate the P(AA/AMPS) dosage and the method of adding P(AA/AMPS), resulting in the selection of a P(AA/AMPS) dosage of 12 wt.‰ (based on the dry GCC), added in sections. Finally, the properties of the ultrafine GCC slurry prepared under optimal conditions were investigated.