Radiation imagery chemistry: process – composition – or product th – Imaged product – Structurally defined
Reexamination Certificate
2001-08-16
2003-07-22
Schilling, Richard L. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaged product
Structurally defined
C430S014000, C430S220000, C430S432000, C430S510000, C430S523000, C430S533000, C430S536000, C430S961000, C347S106000
Reexamination Certificate
active
06596447
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to imaging materials. In a preferred form, it relates to nacreous photographic reflective paper.
BACKGROUND OF THE INVENTION
In reflective photographic papers there is a need to protect the imaging layers from scratches, fingerprints, and stains. Current photographic reflective papers use a gelatin overcoat to protect the imaging layers. While the gelatin does provide some level of protection, it can easily be scratched reducing the quality of the image. Further, fingerprints or stains caused by common household liquids such as coffee, water, or fruit juice can easily stain and distort images. Wiping the images while wet causes undesirable distortion to the gelatin overcoat. Post photographic processing equipment exists that provides a protective coating to the imaging layers. Typically consumer images are individually coated or laminated with a polymer to provide protection to the image layers. A common example is photographic identification badges which are typically laminated with a clear polymer sheet to provide protection to the image on the identification badge. Post processing application of a protective layer is expensive, as it requires an additional step in the preparation of the reflective print and additional materials to provide the overcoat. It would be desirable if a reflective photographic image could be formed with a protective coating over the developed image layers that could be efficiently applied.
It is also well know in the art of imaging to provide a protective over-lamination of the imaging element. This is commonly practiced in the industry. Typically this is a clear polymer sheet with either a pressure sensitive or heat activated adhesive that is applied in a post image formation application. The clear polymer sheet may be polyolefins, polyester or polycarbonate sheet. These sheets may even in textured. There have also been numerous attempts to apply liquid polymer over coats to the image to protect them from damage and handling abuses. There remains a need to provide an over protective layer that not only provides protection to the image but further enhances its value by provide a nacreous appearance to the image.
Prior art reflective imaging output materials such as silver halide reflective images or inkjet reflective images typically comprise imaging layers applied to a white reflective base material. The white reflective base reflects ambient light back to the observer's eye to form the image in the brain. Prior art base materials typically utilize white reflecting pigments such as TiO
2
or barium sulfate in a polymer matrix to form a white reflective base material. Prior art reflective photographic papers also contain white pigments in the support just below the silver halide imaging layers to obtain image whiteness and sharpness during image exposure, as the white pigment reduces the amount exposure light energy scattered by the cellulose paper core. Details on the use of white pigments in highly loaded coextruded layers to obtain silver halide image sharpness and whiteness are recorded in U.S. Pat. No. 5,466,519.
It has been proposed in U.S. Pat. No. 6,071,680 (Bourdelais et al) to utilize a voided polyester sheet coated with light sensitive silver halide imaging layers for use as photographic output material. The voided layer in U.S. Pat. No. 6,071,680 improves opacity, image lightness, and image brightness compared to prior art polyethylene melt extrusion coated cellulose paper base materials. The image base proposed in U.S. Pat. No. 6,071,680 also contains an integral polyolefin skin layer to facilitate imaging layer adhesion at the time of manufacture and during the processing of silver halide imaging layers.
It has been proposed in U.S. Pat. No. 5,866,282 (Bourdelais et al) to utilize a composite support material with laminated biaxially oriented polyolefin sheets as a photographic imaging material. In U.S. Pat. No. 5,866,282, biaxially oriented polyolefin sheets are extrusion laminated to cellulose paper to create a support for silver halide imaging layers. The biaxially oriented sheets described in U.S. Pat. No. 5,866,282 have a microvoided layer in combination with coextruded layers that contain white pigments such as TiO
2
above and below the microvoided layer. The composite imaging support structure described in U.S. Pat. No. 5,866,282 has been found to be more durable, sharper and brighter than prior art photographic paper imaging supports that use cast melt extruded polyethylene layers coated on cellulose paper.
There, however, remains a continuing need for improvements to the appearance of imaging output materials. It has been shown that consumers, in addition to reflective output material, also prefer nacreous images. Nacreous images exhibit a pearly or nacreous luster, an iridescent play of colors, and a brilliant luster that appears in three dimensions. Nacreous appearance can be found in nature if one examines a pearl or the polished shell of
Turbo marmoratus.
A nacreous photographic element with a microvoided sheet of opalescence is described in U.S. Pat. No. 5,888,681 (Gula et al). In U.S. Pat. No. 5,888,681 microvoided polymer sheets with microvoided polymer layer located between a cellulose paper base and developed silver halide imaging provide an image with an opalescence appearance. The nacreous appearance is created in U.S. Pat. No. 5,888,681 by providing multiple internal reflections in the voided layer of the polymer sheet. While the opalescence appearance is present in the image, the image suffers from a loss of image sharpness or acutance, a higher density minimum position, and a decrease in printing speed compared to a typical photographic image formed on a white, reflecting base. It would be desirable if the opalescent look of the image could be maintained while improving printing speed, increasing sharpness, and decreasing density minimum. Also, while the voided polymer does provide an excellent nacreous image, the voided layer, because it is pre-fractured, is subjected to permanent deformation, thus reducing the quality of the image.
Nacreous pigments added to a matrix, such as paint or plastic, have been known to exhibit a nacreous appearance. The prior art use of the nacreous pigments have been for pigmenting paints, printing inks, plastics, cosmetics, and glazes for ceramics and glass. Nacreous pigments are dispersed in a matrix and then painted or printed onto a substrate. Pearl luster pigments containing titanium dioxide have been successfully employed for many years. They are constructed in accordance with the layer substrate principle, with mica being employed virtually without exception as substrate.
Mica pigments are used widely in the printing and coating industries, in cosmetology, and in polymer processing. They are distinguished by interference colors and a high luster. For the formation of extremely thin layers, however, mica pigments are not suitable, since the mica itself, as a substrate for the metal-oxide layers of the pigment, has a thickness of from 200 to 1200 nanometer. A further disadvantage is that the thickness of the mica platelets within a certain fraction defined by the platelet size in some cases varies markedly about a mean value. Moreover, mica is a naturally occurring mineral that is contaminated by foreign ions. Furthermore, technically highly complex and time-consuming processing steps are required including, in particular processing steps are required including, in particular, grinding and classifying.
Pearl luster pigments based on thick mica platelets and coated with metal oxides have, owing to the thickness of the edge, a marked scatter fraction, especially in the case of relatively fine particle-size distributions below 20 micrometers. As a substitute for mica, it has been proposed to use thin glass flakes that are obtained by rolling a glass melt with subsequent grinding. Indeed, interference pigments based on such materials exhibit color effects superior to those of conventional, mica-based pigments. Disadvantages, ho
Aylward Peter T.
Bourdelais Robert P.
Camp Alphonse D.
Eastman Kodak Company
Leipold Paul A.
Schilling Richard L.
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