Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Identified backing or protective layer containing
Reexamination Certificate
1998-12-21
2001-07-31
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Identified backing or protective layer containing
C430S022000, C430S496000, C430S536000, C430S930000
Reexamination Certificate
active
06268117
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to photographic materials. In a preferred form it relates to base materials for photographic clear display that do not have incorporated diffuser layers.
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. Furthermore, 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, photographic processing 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 and tints, rather than being dispersed a single melt extruded layer of polyethylene could be concentrated nearer the surface where they would be more effective optically.
Prior art photographic clear display materials have light sensitive silver halide emulsions coated directly onto a gelatin coated clear polyester sheet. Clear photographic display materials are typically used as overhead materials that are projected on a screen, typically highly reflective and white and display materials that utilize light boxes with a white diffuser screen. Diffuser screens are necessary to diffuse the light source used to backlight clear display materials and to provide the white portion of the image. Without a diffuser, the light source would significantly reduce the quality of the image. Since light sensitive silver halide emulsions that are used for prior art clear display materials tend to be yellow because of the gelatin used as a binder for photographic emulsions, the minimum density areas of a developed image will tend to appear as a yellow white. A yellow white reduces the commercial value of a transmission display material because the imaging viewing public associates image quality with a blue white. It would be desirable if a clear display material could have a more blue white.
Prior art clear display materials use a high coverage of light sensitive silver halide emulsion coated on one side of the base to increase the density of the image compared to photographic reflective print materials. An increase in dye density is required for clear display materials to provide the required dye density associated with a quality image. While increasing the coverage does increase the density of the image in transmission space, the time to image development is also increased as the coverage increases. Typically, a high density clear display material has a developer time of 110 seconds compared to a developer time of 45 seconds or less for photographic reflective print materials. Prior art high density clear display materials, when processed, reduce the productivity of the development lab. Further, coating a high coverage of emulsion requires additional drying of the emulsion in manufacturing reducing the productivity of emulsion coating machines. It would be desirable if a clear display material was high in dye density to provide a quality image and had a developer time less than 50 seconds.
Prior art photographic display material use polyester as a base for the support. Typically the polyester support is from 150 to 250 &mgr;m 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 need for clear display materials that provide improved transmission of light while, at the same time, reducing the yellowness of the density minimum areas of the image.
SUMMARY OF THE INVENTION
It is an object of the invention to provide improved clear display materials.
It is another object to provide display materials that are lower in cost, as well as providing sharp durable images.
It is a further object to provide a clear display materials with a whiter density minimum.
It is an another object to provide a product that may be provided with a silver halide image on each side but still retain a single exposure step and short processing time.
These and other objects of the invention are accomplished by a photographic member comprising at least one photosensitive layer and an integral base material comprising at least one polyester layer and an upper surface layer comprising a polyester or polyolefin polymer and a bluing tint wherein said integral base material has a spectral transmission of greater than 90%.
ADVANTAGEOUS EFFECT OF THE INVENTION
The invention provides whiter images by off setting the yellowness of the light sensitive silver halide emulsion.
DETAILED DESCRIPTION OF THE INVENTION
The invention has numerous advantages over prior clear display materials and methods of imaging transmission display materials. The display materials of the invention provide transmission of a high percentage of the light. The material as it contains in its preferred form silver halide imaging layers on both sides of a polymer sheet that may be imaged by a collimated beam exposure device in a single exposure. As there are two relatively thin layers of silver halide image materials, the developing of the invention element may be carried out rapidly as the penetration of the developing solution is rapid through the thin layers of imaging material. This rapid processing of images allows for efficient and low cost production of overhead slides for sales and business presentations. The materials are low in cost as the transparent polymer material sheet is thinner than in prior products. They are also lower in cost as less gelatin is utilized and no antihalation layer was surprisingly found to be not necessary. The minimum density areas of the clear display material of the invention will appear whiter to the observer than prior art materials which have a tendency to appear somewhat yellow as the light sensitive silver halide emulsions used for clear display materials have a native yellowness. These and other advantages will be apparent from the detailed description below.
The terms as used herein, “top”, “upper”, “emulsion side”, and “face”
Aylward Peter T.
Bourdelais Robert P.
Camp Alphonse D.
Laney Thomas M.
Baxter Janet
Eastman Kodak Company
Leipold Paul A.
Wallace Amanda C.
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