Freeze Coagulation of ABS Latex

Thermoplastic injection and extrusion resins based on acrylonitrile/butadiene/styrene (ABS) are widely used because of their toughness and solvent resistance. When high gloss is necessary, these resins must be produced by emulsion polymerization, which requires that they be coagulated and dewatered before sale. We review the coagulation techniques that are available, discuss the advantages and disadvantages of each, and then focus on coagulation by freezing. We examine two approaches to freeze coagulation: The first involves freezing against a cold surface. The second involves direct contact freezing of a suspension of ABS latex particles in contact with liquid CO2 at about 3340 kPa (485 psia).