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US 5,904,761 AGranted
Process for preparing a pigment for a coated paper
OwnerKyu Jae Youinventor
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Abstract
The present invention provides a method for preparing a needle-shaped pigment with a particle size of 0.3.+-.0.1 .mu.m, which has uniform particle distribution, higher thixotropy, an excellent gloss, and good absorption of printing ink, by continuous addition of aluminum sulfate solution and zinc sulfate solution to a milk of lime.
Claims2
A process for preparing needle-shaped pigment with a mean particle size of 0.3.+-.0.1 .mu.m for a coated paper comprising the steps of:
- (a) continuously admixing an aqueous solution of aluminum sulfate, an aqueous solution of zinc sulfate and an aqueous suspension of calcium hydroxide, wherein each individual solution and suspension has a concentration of 7.+-.2% by weight and a temperature of 40.+-.5.degree. C., wherein the concentration of aluminum sulphate is based on Al.sub.2 O.sub.3, and the amounts of the solutions and the suspension are controlled such that the molar ratios of ZnO to CaO, and ZnO and CaO to Al.sub.2 O.sub.3, are in the range of 0.04 to 0.25/l and 7.+-.0.5/l, respectively;
- and
- (b) aging the resultant suspension.
Dependencies are inferred from the claim text.