Radiation imagery chemistry: process – composition – or product th – Post imaging processing – Including post developing step
Reexamination Certificate
2002-03-27
2003-04-22
Schilling, Richard L. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Post imaging processing
Including post developing step
C430S012000, C430S531000, C430S533000, C430S934000, C430S961000, C430S494000
Reexamination Certificate
active
06551766
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method of improving the usefulness and integrity of motion picture films, especially intermediate film that is used in the production of motion picture print films. In particular, the invention relates to use of an aqueous film-forming polymer dispersion that is applied to the base side of a scratched motion picture film, which upon drying will minimize the appearance and impact of the scratch(s). Motion picture films treated in accordance with the invention can thus be salvaged for subsequent use.
BACKGROUND OF THE INVENTION
Motion picture photographic films used in producing a release print (the film projected in movie theaters) include camera origination film, intermediate film, and the release print film. Current practice for most color motion picture production involves the use of at least four photographic steps. The first step is the recording of the scene onto a camera negative photographic film. While the original negative (typically after editing) may be printed directly onto a negative working print film in a second step to produce a direct release print, most motion picture productions use an additional two intermediate steps. Typically, the original camera negative film is printed onto a negative working intermediate film, such as Eastman Color Intermediate Film, yielding a master positive. The master positive is subsequently printed again onto an intermediate film providing a duplicate negative. Finally, the duplicate negative is printed onto a print film forming the release print.
In practice, several duplicate negative copies are produced from the master positive, and each of the duplicate negatives may then be used to make hundreds of print film copies. This multistep process helps save the integrity of the valuable original camera negative film in preparing multiple release prints. In certain situations, usually involving special effects, intermediate film may be used an additional two or more times in preparing the final duplicate negatives to be used in printing the release prints. In this case, the first duplicate negative is used to print onto intermediate film to produce a second master positive, which is in turn used to produce a second duplicate negative. The second duplicate negative may be then used for printing the release prints.
Motion picture films typically comprise one or more light sensitive silver halide emulsion imaging layers coated on one side of a film base. The occurrence of scratches on the side of the film opposite to the imaging layers (i.e., the “back” side or “base” side of the film) is generally more common because greater effort is taken to avoid scratching the inherently softer imaging layer side in all steps of film handling, processing, printing, and/or projecting. The presence of such scratches on original or duplicate films which are being printed can result in images of the scratch marks themselves being reproduced on the printed film. The impact of such reproduced scratch mark images, as well as actual scratch marks which may be formed in a print film, on the projected print image is of course undesirable. Accordingly, once an intermediate film obtains too many scratches to produce acceptable prints therefrom, another intermediate film needs to be prepared. Considerable time and expense during production of print films can be eliminated if minor damage to the base side of an intermediate film can be “healed” rather than generating a new film. Additionally, if scratches formed on the base side of a print film, visible upon projection, can be minimized or eliminated by “healing”, the quality and duration of use of a print film can also be improved.
The photographic film supports materials used in motion picture intermediate and print film elements typically are synthetic high molecular weight polymeric materials. These support materials may be comprised of various polymeric films, but polyester and triacetate film supports, which are well known in the art, are preferred.
One method of scratch healing which has been employed for older, acetate-based photographic films consisted of transporting the scratched film over a rotating glass wheel immersed in an organic solvent mixture containing esters, ketones, and/or chlorinated hydrocarbons. This solvent blend sufficiently softened the film support so that it could be effectively burnished by the glass wheel, thereby eliminating all but the most severe scratches. Problems with this approach include the use of toxic and flammable organic solvents plus the fact that the approach will not work with newer, less soluble polyester-based films. Although polyester film base is more resistant to scratches and abrasion than cellulose triacetate base films, scratches can still occur which could render an intermediate film useless or dramatically compromise the quality or life expectancy of a print film.
Other approaches of suppressing the impact of scratches on photographic film base have involved alterations to the method of projection. A scratch suppressing illumination system for photographic printing is described in U.S. Pat. No. 4,427,283. This approach, however, is a costly way to compensate for the efect rather than eliminate its presence.
There are numerous references for providing abrasion and scratch resistant protective overcoats for photographic elements, but they primarily rely on a thermal or radiation-cured, cross-linkable coating to be applied prior to extensive handling. Their purpose is primarily to prevent scratching rather than heal already scratched photographic film. These coatings generally tend to be expensive and in some cases employ flammable and toxic monomers and/or coating solvents. Applications utilizing such protective overcoats are described, e.g., in U.S. Pat. Nos. 3,019,131, 3,081,192, 3,097,106, 5,401,541, and 5,633,049. While such cross-linked overcoats provide effective scratch and abrasion resistance, their use requires special additional processing steps following application of the coating and the uneconomical position of treating all film, whether it is scratched or not.
Simpler, less toxic and non-flammable overcoating alternatives are described, e.g., in U.S. Pat. Nos. 5,266,455, 6,268,101, and 6,303,281. These aqueous coating formulations eliminate the issue of flammability and they are relatively non-toxic. However, they rely on either elevated temperature curing, or incorporation of matte particles to provide suitable scratch resistance. Again, they do not address the issue of rendering existing scratches invisible, but rather the prevention of scratches in the first place.
Motion picture films with polyester film supports have recently been introduced which employ a process-surviving antistat backing layer and a protective topcoat on the base side (non image layer side) of the film, where such layers are applied as part of the film manufacturing process. The primary functions of the protective overcoat or barrier layer are to prevent the antistatic layer from interacting with components of the processing solutions, and to provide abrasion resistance. Protective topcoats that may be applied over the antistatic layer can include essentially any known polymeric binder. Useful hydrophobic polymers that may be effectively employed in the protective topcoat include polyurethanes, polyesters, polyamides, polycarbonates, cellulose esters, acrylic polymers, styrenic polymers, and the like. U.S. Pat. No. 5,679,505, e.g., describes the use of aliphatic polyurethanes as preferred polymeric binders for use in motion picture film back side topcoats. While the use of such materials has improved the overall performance of the motion picture film elements, they do not address the problem of healing scratches which may nevertheless be formed after manufacture of the film elements.
European Patent 678,784 A1 is directed towards a method and device for the rejuvenating of a polyester film base, and describes coating and drying of an aqueous film-forming polymer dispersion onto the base side of a scratched polyeste
Kordovski Luba
Smith Thomas M.
Anderson Andrew J.
Eastman Kodak Company
Schilling Richard L.
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