Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
2000-06-29
2001-10-16
McPherson, John A. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
Reexamination Certificate
active
06303283
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to improved emulsions. It particularly relates to improved silver chloride emulsions for color print film.
BACKGROUND OF THE INVENTION
In color print films, particularly those utilized for projection of motion pictures, there is a continuing need for an improvement in grain. Such films as they are projected to enormous size in comparison with the size of the image on the film require a very fine grain to achieve a desirable projection quality.
PROBLEM TO BE SOLVED BY THE INVENTION
There is a continuing need for improvement in graininess in projected images of color print film. There is also a continuing need for improved speed of the emulsions without using larger silver halide grains which will result in increased grain in the projected images of the film.
SUMMARY OF THE INVENTION
It is an object of the invention to overcome disadvantages of prior photographic elements.
It is another object of the invention to provide color print film having reduced grain in projected images.
It is another object of the invention to provide finer grain print film that has higher speed for exposure.
These and other objects of the invention generally are accomplished by a method of forming an emulsion comprising providing a silver chloride emulsion, said emulsion comprising silver chloride grain having a grain volume of 0.001 &mgr;m
3
to 2.2 &mgr;m
3
, adding chemical and spectral sensitizing materials, heating said emulsion to sensitize, cooling said emulsion, and then bringing the sensitized emulsion into contact with iodide and bromide.
In another embodiment of the invention there is formed a photographic element comprising at least one layer comprising silver chloride grains having on their surface between 0.0005 and 0.002 mol I/mol Ag and 0.005 and 0.05 mol Br/mol Ag.
ADVANTAGEOUS EFFECT OF THE INVENTION
The invention provides improved motion picture color print film that has a fine grain image when projected. It particularly provides a finer grain projected image from the blue sensitive layer.
DETAILED DESCRIPTION OF THE INVENTION
The invention has numerous advantages over prior practice in the art. The invention provides projection films that have a fine grain image. Further, these films are of higher speed, allowing lower light exposure of the film. The emulsion forming technique of the invention produces a lower fog emulsion, thereby resulting in greater exposure latitude of the print film. Further, it has surprisingly been found that the films formed with grains produced by the invention wherein they have been formed from emulsions treated with iodide and bromide after finishing are robust in development allowing a wider latitude of developing solution chemistry to produce a satisfactory image. The emulsions of the invention further are formed by a technique that is robust, reliable, and does not require the addition of chemicals that are deleterious to the film elements. The emulsions formed by the method of the invention find their preferred use in the blue-sensitive layer of motion picture color print film. However, they may be utilized in other materials that are formed with silver chloride emulsions such as color paper. Further, particularly with the use of tabular emulsions, it could find use in color negative films and color intermediate films.
The invention emulsions find their preferred use in the blue-sensitive layer of a color print film. There is a need for greater speed and grain size in the print film's blue-sensitive layer because, as is well known in the trade, the reproduction system results in low energies in the blue wavelength region, as the masking dyes in the negative and printer light source limit blue wavelength exposure. However, it is not possible to increase the grain size significantly, as this will result in graininess of the film being increased. Therefore, there is a desire to make the grains faster, but the same or smaller size. Generally, the grains of the color films for the invention have a cubic edge length of between 0.1 &mgr;m and 1.0 &mgr;m for best balance of high speed and low graininess of the developed film.
The grain volume of the silver chloride emulsions of the invention is generally between 0.001 and 2.2 &mgr;m
3
. A preferred grain volume for the preferred cubic silver chloride grains is between 0.14 and 0.5 &mgr;m
3
.
The emulsion of the invention may be any silver chloride emulsion that results in good image quality of the photographic element. Generally, it is possible that the silver chloride emulsion is formed with up to about 5 percent of iodide and bromide formed in the grain. The grain is generally washed prior to the invention treatment after sensitization with bromide and iodide. It has been found preferred to utilize an emulsion of 100 percent or one consisting essentially of 100 percent silver chloride grain, as such grain is more rapidly developable, as the addition of iodide and bromide into the grain during emulsion formation provides increased difficulty in formation and results in a less robust manufacturing process as more materials must be precisely controlled. The silver chloride grains may be suitable morphology. Suitable are tabular and cubo-octohedral grains. Preferred are cubic grains, as these have good photographic properties and low granularity.
In the method of the invention the chemical and spectral sensitization is carried out in a conventional manner in the art.
The emulsion finishing method of the invention may be carried out using any suitable sensitizing dye. Suitable for the invention are the cyanine sensitizing dyes. The cyanine dyes have the general structure as follows:
wherein Z
1
and Z
2
are independently selected from N—R, O, S, and R is a lower alkyl, N=1, 3, or 5 if n>1, then center C may be substituted with lower alkyl, Z
5
and Z
6
represent atoms sufficient to complete a substituted or unsubstituted 5-membered ring, it may be saturated or unsaturated and may have a substituted or unsubstituted benzene or naphthaline fused onto it,
Z
3
or Z
4
may be sulfoalkyl, carboxyalkyl.
Any of the alkyl groups described above include cycloalkyl. Examples of any of the alkyl groups mentioned above are methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, hexyl, octyl, 2-ethylhexyl, and the like. Particular cycloalkyl groups can be cyclopentyl, cyclohexyl, 4-methylcyclohexyl, and the like. Alkenyl groups can be vinyl, 1-propenyl, 1-butenyl, 2-butenyl, and the like. Aryl groups can be phenyl, naphthyl, styryl, and the like. Aralkyl groups (which are a type of substituted alkyl) can be benzyl, phenethyl, and the like. Useful substituents on any of the foregoing or other groups disclosed (including substituents on Z
5
and Z
6
) include halogen, alkyl (particularly lower alkyl), alkoxy, acyl, alkoxycarbonyl, aminocarbonyl, carbonamido, carboxy, sulfamoyl, sulfonamido, sulfo, nitro, hydroxy, amino, cyano, trifluoromethyl, and the like. Any of the foregoing (where possible) may be substituted or unsubstituted.
Examples of suitable dyes are
Preferred dyes are the blue cyanine dyes. The most preferred are the cyanines of Structure I:
Where Z
1
is phenyl, pyrrole, or a fused benzene ring; Z
2
is phenyl, pyrrole or halogen, R
1
and R
2
are acid substituted alkyl groups, A
+
is a counterion.
The most preferred of the Structure I dyes is D1
The Structure I dyes may comprise the entire blue sensitizing dye for the method of the invention.
The Structure I dyes may be combined in an amount up to 60 weight percent of the two dyes with dyes of Structure II. It is preferred that between 25 and 50 weight percent of the total dye be Structure II dye for widest latitude blue light sensitivity. Structure II dyes have the Dye II formula:
wherein:
Y
1
is pyrrole or phenyl,
when X is O, then Y
2
is a 4,5-benzo substituent;
When X is S, then Y
2
is a phenylcarbamoyl or a phenylcarboxamido substituent,
R
3
and R
4
are acid substituted alkyl groups, B
+
is a counterion.
The most preferred Dye II dye for combination, particularly
Klingman Karen J.
Mroczek Susan K.
Eastman Kodak Company
Leipold Paul A.
McPherson John A.
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