Patent ID: 6387296
Filing Date: 2002-05-14
Classification: D21H

Abstract:
A method for whitening a paper coating slip based on synthetic binders which comprises incorporating into said coating slip a whitened polyacrylonitrile powder having a weight-average particle size of less than 1 &mgr;m, or an aqueous suspension of said whitened polyacrylonitrile powder, wherein said polyacrylonitrile powder is whitened with a whitener selected from the group consisting of in whichX represents CH or N, R1 represents CH3 or CH2â€”C6H5 and R2 represents H or SO2â€”CH3; and in whichR3 denotes NH2, CH3, NHâ€”C3H6â€”N(CH3)3+Anâˆ’, C2H4â€”N(CH3)3+Anâˆ’, CH2â€”CH(CH3)â€”N(CH3)3+Anâˆ’, CH(CH3)â€”CH2â€”N(CH3)3+Anâˆ’, C2H4Oâ€”CH(CH3)â€”CH2â€”N(CH3)3+Anâˆ’ or C2H4â€”COâ€”NHâ€”C3H6â€”N(CH3)3+Anâˆ’ and An&ominus; denotes the anion of a mineral acid, formic acid, acetic acid, lactic acid or O3SOCH3.