HEAT STABLE POLYMER, ITS PRODUCTION AND HOLDING AGENT AND FLOWABILITY LOWERING ADDITIVE

摘要

The thermostable polymers are characterised in that they comprise… a) from 16 to 67 mol% of units of the formula I …… b) from 5 to 42 mol% of units of the formula II …… where R<1>, R<2> and R<3> are each, independently of one another, H or CH3, and… c) from 16 to 46 mol% of units of the formula III …… in which R<4> is H or CH3,… and, due to their high heat resistance, are highly suitable as retention agents for aqueous systems and as fluid-loss additives.