Patent ID: 7476272

Claim:
An aqueous paper stock comprising a paper stock slurry of a blend of: (a) pulp; (b) a rutile titanium dioxide pigment slurry having a solids content from 50 wt. % to 92 wt. % by weight of the titanium dioxide pigment slurry; and (c) an alumina trihydrate extender pigment slurry, having a solids content of at least 67.5 wt. % by weight of the extender pigment slurry, comprising: (i) at least 50% by weight of the extender pigment slurry of alumina trihydrate pigmentary particles having an average particle size of at least 0.5 micron; (ii) a dispersant comprising an acrylic dispersing resin, and optionally citric acid; (iii) a rheology modifier consisting of a synthetic hectorite clay in an amount from 0.1 up to about 1% by weight of the total extender pigment slurry formulation; (iv) optionally a compound to adjust pH; (v) a biocide; and (vi) water, wherein at least 50% by weight of the slurry is dispersed alumina trihydrate, whereby the slurry blend comprises 75 to about 50% by weight of rutile titanium dioxide and from 25% to about 50% alumina trihydrate.