Patent ID: 6214956
Filing Date: 2001-04-10
Classification: A61K,A61Q,C08F,C08K

Abstract:
A solvent-free process for making solvent-free, free-flowing, fine white powders of a copolymer product of maleic anhydride (MAN) and a C.sub.1 -C.sub.4 alkyl vinyl ether (AVE) having a specific viscosity of about 0.5 to about 2 (1% wt/v in methyl ethyl ketone, 25.degree. C.) and substantially without residue, odor or taste which comprises precharging a reactor with excess AVE, acetaldehyde as chain transfer agent and 0.01 to 0.2% based upon said product of a free radical initiator, feeding MAN into said precharged reactor over a period of at least 1 hour, said excess AVE being maintained at a mole ratio of AVE:MAN of 12:1 to 7:1, said acetaldehyde being present in said reaction mixture in a predetermined amount of 0.01 to 2% by weight thereof, copolymerizing said monomers at 55-80.degree. C., stripping off excess AVE and drying under vacuum at 40-100.degree. C. to remove any remaining traces of AVE, wherein when said amount of acetaldehyde is 1.75%, said specific viscosity is 0.55. and when said amount of acetaldehyde is 1.0%, said specific viscosity is 1.2.