Radiation imagery chemistry: process – composition – or product th – Imaged product – Structurally defined
Reexamination Certificate
1999-12-22
2001-04-17
Schilling, Richard L. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaged product
Structurally defined
C430S014000, C430S432000, C430S531000, C430S534000, C430S536000, C430S538000, C430S961000
Reexamination Certificate
active
06218059
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to photographic materials. In a preferred form it relates to base materials for photographic reflective display.
BACKGROUND OF THE INVENTION
It is known in the art that photographic display materials are utilized for advertising, as well as decorative displays of photographic images. Since these display materials are used in advertising, the image quality of the display material is critical in expressing the quality message of the product or service being advertised. Further, a photographic display image needs to be high impact, as it attempts to draw consumer attention to the display material and the desired message being conveyed. Typical applications for display material include product and service advertising in public places such as airports, buses and sports stadiums, movie posters, and fine art photography. The desired attributes of a quality, high impact photographic display material are a slight blue density minimum, durability, sharpness, and flatness. Cost is also important, as display materials tend to be expensive compared with alternative display material technology, mainly lithographic images on paper. For display materials, traditional color paper is undesirable, as it suffers from a lack of durability for the handling, photoprocessing, and display of large format images.
In the formation of color paper it is known that the base paper has applied thereto a layer of polymer, typically polyethylene. This layer serves to provide waterproofing to the paper, as well as providing a smooth surface on which the photosensitive layers are formed. The formation of a suitably smooth surface is difficult, requiring great care and expense to ensure proper laydown and cooling of the polyethylene layers. The formation of a suitably smooth surface would also improve image quality, as the display material would have more apparent blackness, as the reflective properties of the improved base are more specular than the prior materials. As the whites are whiter and the blacks are blacker, there is more range in between and, therefore, contrast is enhanced. It would be desirable if a more reliable and improved surface could be formed at less expense.
Prior art photographic reflective papers comprise a melt extruded polyethylene layer which also serves as a carrier layer for optical brightener and other whitener materials as well as tint materials. It would be desirable if the optical brightener, whitener materials and tints, rather than being dispersed throughout the single layer of polyethylene could be concentrated nearer the surface of the layer where they would be more effective optically.
Prior art photographic reflective display materials have light sensitive silver halide emulsions coated directly onto a gelatin coated opacified polyester base sheet. Since the emulsion does not contain any materials to opacify the imaging element, white pigments such as BaSO
4
have been added to the polyester base sheet to provide an imaging element with both opacity and the desired reflection properties. Also, optical brighteners are added to the polyester base sheet to give the sheet a blue tint in the presence of an ultraviolet light source. The addition of the white pigments into the polyester sheet causes several manufacturing problems which can either reduce manufacturing efficiency or reduce image quality. The addition of white pigment to the polyester base causes manufacturing problems, such as die lines and pigment agglomeration, which reduce the efficiency at which photographic display material can be manufactured. It would be desirable if the optical brightener, whitener materials and tints, rather than being dispersed throughout the polyester base sheet, could be concentrated nearer the surface where they would be more effective optically and improve manufacturing efficiency.
Prior art reflective photographic materials with a polyester base use a TiO
2
pigmented polyester base onto which light sensitive silver halide emulsions are coated. It has been proposed in WO 94/04961 to use opaque polyester containing 10% to 25% TiO
2
for a photographic support. The TiO
2
in the polyester gives the reflective display materials an undesirable opalescence appearance. The TiO
2
pigmented polyester also is expensive because the TiO
2
must be dispersed into the entire thickness, typically from 100 to 180 micrometers. This also gives the polyester support a slight yellow tint which is undesirable for a photographic display material. For use as a photographic display material, the polyester support containing TiO
2
must be tinted blue to offset the yellow tint of the polyester causing a loss in desirable whiteness and adding cost to the display material. It would be desirable if a reflective display support did not contain any TiO
2
in the base and TiO
2
could be concentrated near the light sensitive emulsion.
Prior art photographic display material uses polyester as a base for the support. Typically the polyester support is from 150 to 250 micrometers thick to provide the required stiffness. A thinner base material would be lower in cost and allow for roll-handling efficiency, as the rolls would weigh less and be smaller in diameter. It would be desirable to use a base material that had the required stiffness but was thinner to reduce cost and improve roll-handling efficiency.
PROBLEM TO BE SOLVED BY THE INVENTION
There is a continuing need for tough scratch resistant display materials that are low in cost and provide superior whiteness and color saturation.
SUMMARY OF THE INVENTION
It is an object of the invention to overcome disadvantages of prior reflective display materials.
It is another object to provide lower cost, high quality reflective display materials.
These and other objects of the invention are accomplished by a photographic element comprising at least one photosensitive layer, and a base material comprising an upper and lower biaxially oriented polymer sheet separated by a paper sheet, wherein said base material has a thickness of greater than 254 micrometers, a stiffness of greater than 325 millinewtons in any direction, and an upper surface roughness of less than 0.45 micrometers at a spatial frequency of between 0.30 and 6.35 millimeters, and a transmission percent of less than 15 percent.
ADVANTAGEOUS EFFECT OF THE INVENTION
The invention provides improved reflective display materials that provide whiter whites and have higher durability compared with polymer materials. The reflective display materials further provide a wider contrast range and sharper images. The invention materials are lower in cost compared to polymer materials.
REFERENCES:
patent: 3777608 (1973-12-01), Kopf et al.
patent: 4912333 (1990-03-01), Roberts et al.
patent: 5141085 (1992-08-01), Maier et al.
patent: 5212053 (1993-05-01), McSweeney et al.
patent: 5393652 (1995-02-01), Marui
patent: 5422175 (1995-06-01), Ito et al.
patent: 5866282 (1999-02-01), Bourdelais et al.
patent: 5888643 (1999-03-01), Aylward et al.
patent: 5888714 (1999-03-01), Bourdelais et al.
patent: 5902720 (1999-05-01), Haydock et al.
patent: 6020116 (2000-02-01), Camp et al.
patent: 6030742 (2000-02-01), Bourdelais et al.
Aylward Peter T.
Bourdelais Robert P.
Camp Alphonse D.
Eastman Kodak Company
Leipold Paul A.
Schilling Richard L.
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