Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Antihalation or filter layer containing
Reexamination Certificate
1999-08-10
2001-01-30
Schilling, Richard L. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Antihalation or filter layer containing
C430S510000, C430S517000, C430S521000, C430S536000, C430S538000, C430S539000, C347S105000
Reexamination Certificate
active
06180330
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to high quality imaging materials. In a preferred form it relates to materials for photographic color papers and other imaging materials manufactured by using high temperature extruded layers.
BACKGROUND OF THE INVENTION
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 and requires great care and expense to ensure proper laydown and cooling of the polyethylene layers.
In photographic papers the polyethylene layer also serves as a carrier layer for titanium dioxide and other whiting materials as well as tinting materials. By experience, it has been shown that a bluish tint is necessary as the background for images on paper type bases to obtain a favorable response from customers of these products. It would be desirable if the colorant materials rather than being dispersed throughout the polyethylene layer could be included in a layer of the photographic materials that is not subjected to the rigors of high temperature extrusion, which is the most common way of manufacturing the melt extruded polyethylene layer.
The high temperature processing of the polyethylene layer requires tint materials that are expensive because they must be chemically and color stable at temperatures typically over 290 degrees centigrade. It is common to incur clumping of the whitener and tint materials and it may be necessary to resort to special high temperature filtration to minimize objectionable clumping which is seen as undesirable spots in the image.
The compounding of the polyethylene, whiteners, and tinting agents is usually done far in advance of the extrusion of the layer on the base therefore, it is impossible to change the tint significantly if tint changes are needed to accommodate any colorimetric variations of the base materials or subsequent image forming 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.
In European Application EP 585 679 A1, anthraquinone dyes are incorporated into emulsion interlayers as conventional oil and water dispersions. The anthraquinone dye dispersions used both ethyl acetate and a high boiling permanent solvent to dissolve the organic compounds prior to incorporation into the photographic emulsion coated on a support consisting of a high density polyethylene coated on a base paper. Incorporating oil and water dispersion pigments as disclosed in EP 585 679 A1 is undesirable because pigments, by nature, are insoluble, crystalline solids, which are the most thermodynamically stable form that they can assume. In an oil and water dispersion, they would be in the form of an amorphous solid, which is thermodynamically unstable. Therefore, one would have to worry about the pigment eventually converting to the crystalline form with age. A further problem with the use of ethyl acetate and a high boiling point solvent is that the high boiling solvent is not removed with evaporation, and it will cause unwanted interactions in the coating melt such as ripening of Ostwald oxidized developer scavenger of dispersion particles, or other components in the other imaging layers. It would be desirable if pigments could be incorporated into the imaging layers without the use of ethyl acetate and high boiling point permanent solvents.
PROBLEM TO BE SOLVED BY THE INVENTION
There is a need for improved methods of providing a generally blue tint to substrates comprising the base of the imaging element without clumping of pigments and at lower cost and with more flexibility to accommodate colorimetric variations of the base materials or subsequent image forming layers. Further, there is a need to avoid the need for high boiling point solvents for the incorporation of pigments into the imaging layers.
SUMMARY OF THE INVENTION
It is an object of the invention to provide improved tinting of imaging materials.
It is another object to provide lower cost tints in imaging materials.
It is a further object to provide the use of stable pigments in imaging materials which can be used at lower temperatures during the assembly process.
It is an additional object to provide better dispersion of tinting materials in imaging elements.
These and other objects of the invention are generally accomplished by an imaging element comprising a reflective base and at least one gelatin containing layer, said at least one layer comprising a dispersion of solid particle pigments of a particle size less than 1.0 micrometer.
ADVANTAGEOUS EFFECT OF THE INVENTION
The invention provides lower cost tinting of color imaging materials. It further provides greater flexibility in tinting of imaging materials and greater selection of pigments for tinting of imaging materials.
DETAILED DESCRIPTION OF THE INVENTION
The invention has numerous advantages over prior methods of tinting of imaging materials. The invention provides the ability to use lower cost and lower amounts of pigments as they are applied in low temperature gelatin systems. Further, the invention provides the ability to easily change tint levels during manufacturing as tinting is carried out as the element is laid down and is not fixed by the choice of substrate. In conventional color photographic paper the tints are added into the waterproofing polyethylene layers on the base paper. These tints are generally mixed into the polyethylene long before coating, and their color may change prior to coating being carried out. The tints are added by the manufacture of the polyethylene and arrive in pelletized form. It is difficult to determine what tint a layer formed with these pellets will have without actually coating the pellets onto paper. It would be desirable if tint could be adjusted during manufacturing rather than relying on polymer supplies to be consistent. In the instant invention colorant is not added to the imaging element until the moment of emulsion coating and, therefore, the colorant will not change prior to laydown. The prior colorants utilized in tinting base materials had a tendency to clump during coating. This clumping led to irregularities in image quality in photographic elements. The filtering of polyethylene polymers to remove clumping has been attempted. However, such filtering is expensive and not completely successful as clumping still takes place and is present in the laydown material. The pigments coated from gelatin layers are much less susceptible to clumping resulting in a more uniform photographic element. The pigments of the invention are an aqueous solid particle dispersion added directly to the imaging layer or layers. The aqueous dispersion of solid particle pigments overcomes the problems associated with a high boiling point solvent and avoids the problem of the pigment eventually converting to the crystalline form with age. These and other advantages will be apparent from the detailed description below.
Table 1 is the typical assembly of a photographic print with the following details:
A. A multilayered gelatin formulation with many distinct layers which will be exposed to light and developed to provide a color image only in the areas that are needed to imitate the image as photographed
C. A typical waterproof monolayer of polyethylene with additives for color tint adjustment and whiteness
D. A comparatively thick layer of paper fiber to provide the necessary product thickness, opacity, and stiffness
E. A typical waterproof monolayer of clear polyethylene with an outside surface roughness sufficient to reflect light to give a dull appearance.
Table 1A shows the addition of layer B. which is an addit
Bourdelais Robert P.
Brick Mary Christine
Gula Thaddeus S.
Sawyer John F.
Eastman Kodak Company
Leipold Paul A.
Schilling Richard L.
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