Processes to prepare polymer solutions from polymer melts

摘要

A number of different materials are used to modify the flow properties of liquid formulations, preferably latex paints. In the 1970's the market began to move to so-called nonionic associative thickeners. The vast majority of these materials are based on polyethylene glycol or polyalkylene oxides containing a high amount of ethylene oxide based repeating units, but they require a reaction step to increase the molecular weight and to add hydrophobic associating groups onto the polymers. There are numerous technologies employed to achieve this reaction. The most common chemical technologies used to make associative thickener polymers use isocyanates to create urethane thickeners (HEUR, cf. US 4,079,028 B1 and US 4,155,892 A) or aminoplast linkers to provide aminoplast thickeners (HEAT, cf. US 5,627,232 A and US 5,914.373 A).