Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Structurally defined
Reexamination Certificate
2001-11-28
2002-11-05
Schilling, Richard L. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Structurally defined
C430S505000, C430S523000, C430S531000, C430S536000, C430S537000, C430S950000, C430S961000
Reexamination Certificate
active
06475712
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a photographic element with improved physical properties of its surface layer. More specifically, this invention relates to a photographic element having a surface protective layer that contains a composite wax particle having a wax phase and a polymer phase, where the polymer phase is soluble in alkaline photographic processing solutions.
BACKGROUND OF THE INVENTION
During the manufacture and use of a photographic element, for example, during coating, drying, finishing, winding, rewinding, printing, projecting, and so on, the surfaces of a photographic element are often damaged by contact with various equipment or as a result of contact between the front and back side of the element. This damage is typically scratches or abrasion marks that are visible during viewing of the processed photographic element (i.e., film, slide or paper print). The photographic print itself may be scratched or the scratch may be copied during printing of a damaged negative. In either case, scratch and abrasion represent significant problems in the practical use of photographic films. This is especially true in recent years since the conditions under which photographic materials are manufactured or used have become more severe. For example, in Advanced Photographic System cameras which provide a mid roll interrupt feature the film cassette may be wound and unwound several times before the entire roll of film is exposed. In addition, photographic film and paper are now coated, finished, and printed at higher speeds than ever before in order to improve productivity. Transporting photographic film and paper at these higher speeds make them more susceptible to damage by scratch and abrasion.
To improve scratch and abrasion resistance, a lubricant or slipping agent is often used in the surface layers of photographic elements. Representative examples of the lubricants used for this purpose include silicone derivatives, esters of long-chain fatty acids and alcohols, tetrafluoroethylene particles, natural and synthetic waxes such as paraffin wax, polyethylene wax, and carnauba wax, and others as described in
Research Disclosure
, Number 38957, September 1996, pages 613-614.
The addition of lubricants also lowers the coefficient of friction of the surface layer. In the past, this has been desirable since it improves the transport of the photographic film during manufacture and use. However, the desire to further improve the scratch and abrasion resistance of photographic films has led to the need for large amounts of lubricants in the surface layers, which has resulted in surface layers having a very low coefficient of friction (for example, coefficient of friction values less than about 0.15). Although incorporating high concentrations of lubricants provides excellent resistance to scratch and abrasion, the low coefficient of friction which results from use of such high lubricant levels may compromise the handling and wound roll stability during manufacturing, shipping, and storage of the film. As discussed in U.S. Pat. No. 5,679,505, e.g., when the coefficient of friction is below about 0.15 there is a significant danger that long, slit rolls (for example, the roll geometries often employed in the motion picture industry) may become unstable in storage or shipping and become telescoped or dished (i.e., the center of the roll slides outward from the core). During the manufacturing process, telescoping may also occur while handling and shipping long master rolls of film (prior to film slitting). Thus one often faces a dilemma when designing surface protective layers for photographic elements.
In many photographic applications, resistance to scratch and abrasion is most critical after the film has been exposed and processed. For example, for a motion picture print film that is used for theater display, the processed film must be sufficiently durable to withstand perhaps 100 or more passes through a projector. The raw (unprocessed) print film is also desirably resistant to scratch and abrasion, however, it is not subjected to the same level of wear and tear as the processed film. For this reason, it has long been a practice in the motion picture industry to apply a common paste wax to the edges of a print film after processing (“edge waxing”), which process primarily provides protection in the vicinity of the film perforations where the soundtracks are located. Since the wax is applied after processing, the coefficient of friction, and therefore, the winding and roll stability of the raw print film during manufacturing, shipping, and printing are not compromised. However, while edge waxing has proved to be fairly effective, it is a time consuming and messy procedure.
The incorporation of matting agents in the outermost layers of photographic elements is also well known. These matting agents can reduce the potential for a photographic film to ferrotype when the backside of the film is in contact with the frontside (i.e., emulsion side) of the film under the pressures that are typical of, for example, a tightly wound roll of film. Ferrotyping may cause the two sides of the film to stick together, and, under severe cases of ferrotyping, damage to the emulsion side surface layer may occur when the roll is unwound. In some cases, ferrotyping may have an adverse effect on the sensitometric response of the photographic emulsion. Matting agents are also employed for such purposes as reduction of static charging and excessive sheen, pencil mark acceptance and avoidance of Newton's rings. A wide variety of materials have been employed as matting agents including both inorganic and polymeric fine particles as illustrated by
Research Disclosure
, Item 38957, pages 615-616, September, 1996.
Large quantities of matting agents are often employed for the purposes described above. However, the use of a large quantity of matting agent may result in undesirable side effects such as increased haze and graininess of the processed image. To overcome these limitations, a matting agent that is removed during film processing is often employed in place of “permanent” matting agents. Such “removable” or “soluble” matting agents are typically alkali soluble polymeric matte particles comprising, for example, a copolymer of methyl methacrylate and methacrylic acid. Soluble matte particles are described, for example, in U.S. Pat. Nos. 2,322,037; 2,992,101; 3,767,448; 4,094,848; 4,142,894; 4,447,525 and 4,524,131.
Composite particles comprising wax (or lubricant) and polymer, and uses of such composite particles in photographic element layers, have been described previously in U.S. Pat. Nos. 5,695,919, 5,958,658 and 6,165,702. Although these references generally relate to composite wax particles, they are primarily directed towards providing lubricants especially suited for dispersibility in organic solvent coating systems. These references do not teach or suggest the use or benefits of a protective surface layer containing a composite wax particle having a polymer phase which is soluble in alkaline photographic processing solutions.
It would be desirable to provide an improved surface protective layer for photographic elements that is easily manufactured and that has both very good resistance to scratch and abrasion after photographic processing and which is not prone to telescoping during manufacture, storage, and shipping.
SUMMARY OF THE INVENTION
In accordance with the present invention there is provided an unprocessed photographic element comprising a support, at least one image-forming layer, and at least one surface protective layer that contains a polymeric binder and composite wax particles having a wax phase and a polymer phase, wherein the polymer phase is soluble in alkaline photographic processing solutions. The surface protective layer of elements in accordance with the invention advantageously enables a change in frictional characteristics after film processing in alkaline solutions which enables the photographic element to have both pre-processed wound roll stability a
Anderson Charles C.
Wang Yongcai
Anderson Andrew J.
Eastman Kodak Company
Schilling Richard L.
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