Hydrolyzed water-resistant protective overcoat for an imaging element

#The present invention relates to photographic elements having a protective overcoat that resists fingerprints, common stains, and spills. More particularly, the present invention provides a processing-solution-permeable protective overcoat that is water resistant in the final processed product. The overcoat, before formation of the image, comprises hydrophobic polymeric particles in a gelatin matrix. Subsequent treatment of the overcoat, after formation of the image, to remove the gelatin, causes coalescence of the hydrophobic particles, resulting in the formation of a water-resistant continuous protective overcoat.

#Gelatin has been used extensively in a variety of imaging elements as the binder because of its many unique and advantageous properties. For example, its property of water swellability allows processing chemistry to be carried out to form silver halide-based photographic images, and its hydrophilic nature allows gelatin to function as an ink-receiver in ink-jet recording media. However, due to this same property, imaging elements with exposed gelatin-containing materials, no matter if they are formed on transparent or media, have to be handled with extreme care so as not to be in contact with any aqueous solutions that may damage the images. Accidental spillage of common household solutions such as coffee, punch, or even plain water can damage imaging elements such as photographic prints.

#There have been attempts over the years to provide protective layers for gelatin-based photographic systems that will protect the images from damage by water or aqueous solutions. U.S. Pat. No. 2,173,480 describes a method of applying a colloidal suspension to moist film as the last step of photographic processing before drying. A number of patents describe methods of solvent coating a protective layer on the image after photographic processing is completed and are described, for example, in U.S. Pat. Nos. 2,259,009, 2,331,746, 2,798,004, 3,113,867, 3,190,197, 3,415,670 and 3,733,293. More recently, U.S. Pat. No. 5,376,434 describes a protective layer formed on a photographic print by coating and drying a latex on a gelatin-containing layer bearing an image. The latex is a resin having a glass transition temperature of from 30° C. to 70° C. Another type of protective coating involves the application of UV-polymerizable monomers and oligomers on a processed image followed by radiation exposure to form crosslinked protective layer, which is described in U.S. Pat. Nos. 4,092,173, 4,171,979, 4,333,998 and 4,426,431. A drawback for both the solvent coating method and for the radiation cure method is the health and environmental concern of those chemicals or radiation to the coating operator. Another drawback is that the photographic materials need to be coated after the processing step. Thus, the processing equipment needs to be modified and the personnel running the processing operation need to be trained to apply the protective coating.

#The present invention is illustrated by the following Examples.

#Characterizations of polymeric materials in the following examples were obtained by the following tests or analytical techniques:

#Glass Transition Temperature and Melting Temperature