Propoxylated-ethoxylated Block Copolymers
A demulsifier composition that is a blend of a propoxylated-ethoxylated block copolymer of a bis-hydroxy alkylether and a propoxylated-ethoxylated block copolymer of 2-hydroxymethyl-1, 3-propanediol has been described.
The blend is partially crosslinked with a vinyl monomer when dissolved in an organic aprotic solvent and has a pH of 5.0 or lower. The first block copolymer is prepared by polycondensing a bis-hydroxyalkyl ether with propylene oxide. Next, the resulting propoxylated diol is reacted with ethylene oxide to produce the block copolymer. The second copolymer is prepared by polycondensing 2-amino-2-hydroxymethylp-1, 3-propanediol, commonly known as TRIS, with propylene oxide to provide a polymer having preferably 10 to 25 oxypropylene units. Next, the propoxylated diol is reacted with ethylene oxide to produce the block copolymer having preferably 5 to 10 ethylene oxide units. The two block copolymers are dissolved together in an organic aprotic solvent, such as toluene, xylene, trialkylbenzene, cyclohexane, heptane, and hexane.