Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Two or more radiation-sensitive layers containing other than...
Reexamination Certificate
2000-08-31
2001-12-04
Schilling, Richard L. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Two or more radiation-sensitive layers containing other than...
C430S510000, C430S523000, C430S527000, C430S531000, C430S536000, C430S537000, C430S539000, C430S961000
Reexamination Certificate
active
06326131
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to imaging elements, and more particularly in a specific embodiment to a motion picture print film photographic elements with improved resistance to abrasion and dust generation in projection equipment.
BACKGROUND OF THE INVENTION
Motion picture photographic film elements that are used as print films for movie theater projection have long used a carbon black-containing layer on the backside of the film. This backside layer provides both antihalation protection and antistatic properties prior to film processing. The carbon black is applied in an alkali-soluble binder that allows the layer to be removed by a process that involves soaking the film in alkali solution, scrubbing the backside layer, and rinsing with water. This carbon black removal process, which takes place prior to image development, is both tedious and environmentally undesirable since large quantities of water are utilized in this film processing step. In addition, in order to facilitate removal during film processing, the carbon black-containing layer is not highly adherent to the photographic film support and may dislodge during various film manufacturing operations such as film slitting and film perforating. Carbon black debris generated during these operations may become lodged on the photographic emulsion and cause image defects during subsequent exposure and film processing.
After removal of the carbon black-containing layer, antistatic properties provided thereby are lost. Undesired static charge build-up can then occur on processed motion picture print film when transported through projectors or on rewind equipment. While discharge of high static charges does not cause static marks on the processed photographic film as the film's light sensitive silver halide has also been removed during film processing, high static charges can attract dirt particles to the film surface. Once on the film surface, these dirt particles can create abrasion or scratches or, if sufficiently large, the dirt particles may be seen on the projected film image.
U.S. Pat. No. 5,679,505 describes a motion picture print film which, in place of a carbon black-containing layer on the backside of the film, contains an antihalation undercoat on the front side of the film support under the film emulsion layers, and an antistatic layer and a protective overcoat on the backside of the support. The protective overcoat is comprised of a polyurethane binder and lubricant. The polyurethane binder has a tensile elongation to break of at least 50% and a Young's modulus measured at 2% elongation of at least 50000 lb/in
2
. Despite the toughness of this overcoat, abrasive wear and the subsequent dust generation have continued to be a problem with protective overcoats in motion picture print film. During the lifetime of a print in a theater, abrasions in the perforation area can become severe enough that the soundtrack is damaged. In addition, dust can build up in the picture area of the film and reduce the quality of the projected image.
One approach that greatly reduces projector dust is to heavily lubricate the overcoat. However, at the lubricant levels necessary to reduce dusting in projectors, the coefficient of friction of the overcoat is reduced to the point that such a film is non-manufacturable because support rolls have insufficient traction for satisfactory conveyance in high speed sensitizing machines, and also because the long, slit rolls of photographic film become telescoped or dished in storage or shipping, wherein the roll integrity is at risk. It would be desirable to reduce projector dust by providing a print film with a highly lubricated protective overcoat having a sufficiently high coefficient of friction to eliminate the above manufacturing difficulties.
SUMMARY OF THE INVENTION
In accordance with one embodiment of the invention, an imaging element is disclosed comprising a support, an imaging layer, and an outermost protective layer on at least one side of the support which comprises a lubricant and an additive which is immiscible with and more surface active than the lubricant, wherein the lubricant is present in an amount of at least 5 mg/m
2
and the additive is present in an amount of at least 25 wt percent relative to that of the lubricant, the amount of additive being effective to increase the coefficient of friction for the outermost layer after coating and drying thereof relative to that obtained in the absence of the additive material.
In accordance with a preferred embodiment of the present invention there is provided a motion picture photographic film element comprising a support having on a front side thereof an antihalation undercoat and at least one silver halide emulsion layer, and on the back side thereof an antistatic layer and an outermost protective layer which comprises a lubricant and an additive as described above.
In accordance with a particularly preferred embodiment of the present invention there is provided a color motion picture print film element comprising a support having on a front side thereof, in order, an antihalation undercoat, a yellow dye image-forming unit comprising at least one blue-sensitive silver halide emulsion layer having associated therewith at least one yellow dye-forming coupler, a cyan dye image-forming unit comprising at least one red-sensitive silver halide emulsion layer having associated therewith at least one cyan dye-forming coupler, and a magenta dye image-forming unit comprising at least one green-sensitive silver halide emulsion layer having associated therewith at least one magenta dye-forming coupler, and on the backside thereof an antistatic layer and an outermost protective layer which comprises a lubricant and an additive as described above.
Imaging elements comprising highly lubricated protective outermost layers in accordance with the invention advantageously provide increased scratch and wear resistance, while the presence of an additive which is immiscible with and more surface active than the lubricant surprisingly has been found to increase the coefficient of friction to provide good manufacturability of the imaging element.
DETAILED DESCRIPTION OF THE INVENTION
Outermost protective layers in accordance with this invention can be used for many different types of imaging elements where it is desirable to provide increased protection against wear (e.g., during manufacture or subsequent use of the imaging element) while retaining sufficiently high coefficients of friction to enable good manufacturability. The outermost protective layers in accordance with the invention are particularly useful as protective layers coated over imaging element antistatic layers. While the invention is applicable to a variety of imaging elements such as, for example, photographic, electrostatophotographic, photothermographic, migration, electrothermographic, dielectric recording and thermal-dye-transfer imaging elements, the invention is primarily applicable to photographic elements, particularly silver halide photographic elements, and more particularly motion picture print film elements. Accordingly, for the purpose of describing this invention and for simplicity of expression, photographic elements will be primarily referred to throughout this specification; however, it is to be understood that the invention also applies to other forms of imaging elements.
The materials employed as the support member for imaging elements in accordance with the invention may be, e.g., paper, synthetic high molecular weight polymeric materials, or laminates thereof. These materials may be comprised of various polymeric films, but polyester (e.g., poly(ethylene terephthalate) and poly(ethylene naphthalate)) and cellulose triacetate film supports, which are well known in the art, are preferred. The thickness of the support is not critical. Conventional support member thicknesses of from about 50 to 250 microns (2 to 10 mils, or 0.002 to 0.010 inches) can be employed, for example, with very satisfactory results. Polyester supports typic
Nair Mridula
Schell Brian A.
Anderson Andrew J.
Eastman Kodak Company
Schilling Richard L.
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