Patent ID: 8088213

Claim:
A method of preparing a stable dispersion of flocculated filler particles having a specific particle size distribution for use in papermaking processes comprising: a) providing an aqueous dispersion of filler particles; b) adding a first flocculating agent to the dispersion in an amount sufficient to mix uniformly in the dispersion without causing significant flocculation of the filler particles, the first flocculating agent being a flocculant, being anionic and having an RSV of at least 10 dL/g wherein there are no paper fibers present in the dispersion; c) adding a second flocculating agent to the dispersion after adding the first flocculating agent, in an amount sufficient to initiate flocculation of the filler particles in the presence of the first flocculating agent, the second flocculating agent being of opposite charge to the first flocculating agent and being cationic; d) shearing the flocculated dispersion to provide a dispersion of filler flocs having the desired particle size; and e) steps a) through d) are performed prior to adding the dispersion of filler flocs to paper fibers.