Importance

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Abstract

A process for making a direct dispersion of a photographically useful material is disclosed comprising subjecting a mixture of an aqueous gelatin solution, a liquid organic phase comprising a photographically useful material, and an ionic polymer to conditions of high shear or turbulence to form a fine dispersion of the organic phase having an average particle size of less than 0.5 micron dispersed in the aqueous solution; wherein the ratio of the organic phase viscosity to the aqueous gelatin solution viscosity in the absence of the ionic polymer, measured at the temperature of the dispersion forming step, is greater than a value of 2.0, and the ionic polymer is a water soluble or dispersible substantially non-surface active polyelectrolyte which has a molecular weight of at least 10,000 selected from: i) synthetic polymers derived from at least 5 mole % of monomers which contain --OSO.sub.3 M, --SO.sub.3 M, --COOM, or ---OPO(OM).sub.2 substituent groups where M represents a hydrogen atom or a cationic counterion, and ii) polysaccharide materials bearing at least one substituent group as described in i) per saccharide unit. The present invention facilitates the creation of finely dispersed liquid organic phase oil drops containing an oil soluble PUM, without the need of an auxiliary solvent, without the need to add high levels of the hydrophilic colloid and without the need to use high homogenizing temperatures. Further, the present invention facilitates the preparation of equally fine particle dispersions when the level of permanent solvent has been reduced.

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First Claim