Eastman-kodak Company

James T Beck

Pranab Bagchi

Krishnan Chari

Brian Thomas

Steven J Sargeant

Lia A Crede

Vincent J Flow

The invention discloses a continuous method of manufacture of gelled dispersion melts of 'small-particle' microprecipitated photographic agents. The continuous melt manufacturing process of this invention provides dispersion melts that are invariant in agent concentration, melt viscosity, and turbidity as a function of the run time and are also very reproducible and robust in repetitive preparations. Many photographic melts of this invention exhibit high photographic activity and light stability of the agents when exposed to light.

Continuous manufacture of gelled microprecipitated dispersion melts

This invention describes a process of coprecipitating a photographic material such as a dye-forming coupler inside a base ionizable polymeric particle. Preparation of such a dispersion is performed by providing a first flow comprising a solution of a surfactant in water containing a polymer ionizable by base, providing a second flow comprising a water miscible solvent, base, water, and the photographic material, then mixing the said first and said second flow and immediately neutralizing the mixed flow to precipitate the photographic material inside the polymer particles forming a fine particle colloidal dispersion of the photographic material. The polymer dispersions of the invention are characterized by high photographic activity and high dye-stability in some cases.

Polymer co-precipitated coupler dispersion

The invention provides stable dispersions of couplers and methods of their formation. The stable dispersions are formed by the use of a nonionic water soluble polymer in combination with an anionic surfactant having a sulfate or sulfonate head group and a hydrophobic group of 8 to 20 carbons. The preferred nonionic water soluble polymers are polyethyleneoxide and polyvinylpyrrolidene. It is preferred that the dispersions have a pH of between about 5 and 5.5.

Stabilization of precipitated dispersions of hydrophobic couplers

The invention is performed by providing a first flow of water and surfactant, a second flow comprising solvent, base and photographic material, and mixing said first and second streams and either simultaneously or immediately following thereof neutralizing said streams to prevent hydrolysis of a hydrolyzable surfactant and/or premature precipitation of particles before neutralization. The streams then may be immediately treated for formation into photographic materials. In a preferred method the first and second stream may be brought together immediately prior to a mixer with addition of acid directly into the mixer to neutralize the dispersion of fine particles.

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Rochester, NY, United States of America

James T Beck