Patent ID: 6512087
Filing Date: 2003-01-28
Classification: C08G,G03F

Abstract:
A method for separating and isolating low molecular weight oligomers of a film forming resin, said method comprising:a) providing a solution of the film forming resin in a first solvent system comprising a photoresist solvent, and optionally a water-soluble organic polar solvent, wherein the ratio of the photoresist solvent to the water soluble organic polar solvent ranges from about 10/90 to about 100/0; b) providing a second solvent system comprising at least one substantially pure C5-C8 alkane and/or at least one alkyl aromatic hydrocarbon solvent and/or water/C1-C4 alcohol mixture provided that the C1-C4 alcohol content of the water/C1-C4 alcohol mixture is less than 50% by weight; and performing steps c)-e) below in the following order: c) mixing the solutions from a) and the second solvent system from b) in a static mixer for a time period sufficient for efficient mixing; d) feeding the mixture from c) and the second solvent system from b) through two separate inlet ports into a liquid/liquid centrifuge, one of said inlet ports feeding the mixture from c), the second inlet port feeding the second solvent system from b) into said liquid/liquid centrifuge at a feed ratio of the mixture from c) to the second solvent system from b) of from about 10/90 to about 90/10, at a temperature of from about 0Â° C. up to a maximum temperature that is less than the boiling point of the lowest boiling solvent in the first or second solvent system; e) rotating the mixture from step d) inside the liquid/liquid centrifuge at a rotational speed sufficient to separate the mixture from step d) into two separate phases, and then collecting the two separate phases, each from two separate outlet ports, into two separate containers, wherein the heavier phase (H) comprises a fractionated film forming resin comprising higher molecular weight fractions of the film forming resin, in the first solvent system with a minor amount of the second solvent system, and the lighter phase (L) comprises low molecular weight oligomers of the film forming resin in the second solvent system with a minor amount of the first solvent system.