Aluminum trihydrate containing slurries
View Patent ↗The present invention relates to Aluminum trihydrate slurries comprising aluminum trihydrate particles, an acrylic dispersant, citric acid, synthetic hectorite clay, optionally a compound to adjust pH, a biocide and water. These slurries may be mixed with titanium dioxide slurries to produce a stable slurry blends useful in paper and paper-board applications.
1. 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.
2. The aqueous paper stock of claim 1 wherein the slurry blend is FDA compliant for indirect food contact.
3. The aqueous paper stock of claim 1 wherein at least 67-68% by weight of the alumina trihydrate extender pigment slurry is dispersed alumina trihydrate pigmentary particles.
4. The aqueous paper stock of claim 1 wherein the Brookfield viscosity of the extender pigment slurry is less than 1500 cps at 20 rpm.