Abstract The invention relates to improved mineral fillers for use in papermaking. The particulate filler is treated with polymeric material including both anionic and cationic groups, which coagulates or flocculates to coat the particles of filler and cause them to agglomerate. The flocculent filler has improved retention in a paper web, more importantly the invention enables calcium carbonate (for example chalk whiting) to be employed as a mineral filler because the coagulated polymer protects the mineral from the acidic alum in the paper stock. The preferred polymeric material is a mixture of anionic starch derivative and cationic starch derivative. The filler may be mixed with aqueous solutions of the starch derivatives or may be mixed with dry starch derivatives and stirred in water before use.
A METHOD OF TREATING PARTICLES OF CALCIUM CARBONATE FILLER TO REDUCE ITS SENSITIVITY TO PAPERMAKERS'' ALUM WHICH COMRPISES DISSOLVING CATIONIC AND ANOINIC STARCH DERIVATIVES IN WATER TO FORM AN AQUEOUS SOLUTION, MIXING SAID FILLER PARTICLES WITH SAID STARCH DERIVATED IN THE RESULTING AQEOUS SOLUTION, WHEREIN THE TOTAL WEIGHT OF THE ANOIONIC AND CATIONIC STARCH DERIVATIVES IS AT LEAST ABOUT 4% OF THE WEIGHT OF THE FILLER PARTICLES, AND WHEREIN THE WEIGHT RATIO OF ANIONIC TO CATIONIC STARCH IS FROM 1*1 TO 2:1, AND DEPOSITING SAID STARCH DERIVATIVES IN MUTUALLY COAGULATED ADMIXTURE ON SAID PARTICLES.
Claim 2
Independent Claim
94 words
A METHOD OF TREATING PARTICLES OF CALCIUM CARBONATE FILLER TO REDUCE ITS SENSITIVITY TO PAPERMAKERS'' ALUM WHICH COMRPISES DISSOLVING CATIONIC AND ANOINIC STARCH DERIVATIVES IN WATER TO FORM AN AQUEOUS SOLUTION, MIXING SAID FILLER PARTICLES WITH SAID STARCH DERIVATED IN THE RESULTING AQEOUS SOLUTION, WHEREIN THE TOTAL WEIGHT OF THE ANOIONIC AND CATIONIC STARCH DERIVATIVES IS AT LEAST ABOUT 4% OF THE WEIGHT OF THE FILLER PARTICLES, AND WHEREIN THE WEIGHT RATIO OF ANIONIC TO CATIONIC STARCH IS FROM 1*1 TO 2:1, AND DEPOSITING SAID STARCH DERIVATIVES IN MUTUALLY COAGULATED ADMIXTURE ON SAID PARTICLES.
Claim 3
Dependent Claim
30 words
A method according to claim 1 wherein separate aqueous solutions of said anionic and cationic starches are prepared and said solutions are mixed with the filler particles prior to deposition.
Claim 4
Dependent Claim
28 words
A method according to claim 1 in which a dry mixture of said anionic and cationic starches and the filler particles is stirred in water prior to deposition.
Claim 5
Dependent Claim
17 words
A method according to claim 1 in which the starches are treated with glyoxal to insolubilize them.