Method for the preparation of graft polymer dispersions having broad particle size distribution without wildly fluctuating viscosities

Claim 1

A method for preparing graft polymer dispersions having broad particle sized distribution comprising: (a) Preparing an intermediate graft polymer dispersion containing 30 percent by weight or less solids to achieve a broad distribution of particle sizes in a continuous process, by feeding a mixture of a polyoxyalkylene polyol, an unsaturated polyol, an ethylenically unsaturated monomer or mixture of ethylenically unsaturated monomers, and a free radical initiator into a continuous flow reactor containing a starting seed graft polyol at a temperature of from about 25° C. to about 180° C.; and, (b) Charging the intermediate graft polymer dispersion of (a) to a semi-batch reactor as seeds for further grafting to increase the solids content of the dispersion to about 40 percent by weight, by feeding an amount of an ethylenically unsaturated monomer calculated to raise the solids content to the desired level, and a free radical initiator into the semi-batch reactor at the same temperature as in (a), wherein the particles generally grow large but retain the characteristics of broad size distribution.

Claim 2

A method for preparing graft polymer dispersions having broad particle sized distribution comprising: (a) Preparing an intermediate graft polymer dispersion containing 30 percent by weight or less solids to achieve a broad distribution of particle sizes in a continuous process, by feeding a mixture of a polyoxyalkylene polyol, an unsaturated polyol, an ethylenically unsaturated monomer or mixture of ethylenically unsaturated monomers, and a free radical initiator into a continuous flow reactor containing a starting seed graft polyol at a temperature of from about 25° C. to about 180° C.; and, (b) Charging the intermediate graft polymer dispersion of (a) to a semi-batch reactor as seeds for further grafting to increase the solids content of the dispersion to about 40 percent by weight, by feeding an amount of an ethylenically unsaturated monomer calculated to raise the solids content to the desired level, and a free radical initiator into the semi-batch reactor at the same temperature as in (a), wherein the particles generally grow large but retain the characteristics of broad size distribution.