Spectrally sensitized tabular grain photographic materials

Details Spectrally sensitized tabular grain photographic materials Spectrally sensitized tabular grain photographic materials

1994-06-29

2001-08-28

Letscher, Geraldine (Department: 1752)

Radiation imagery chemistry: process, composition, or product th

Radiation sensitive product

Two or more radiation-sensitive layers containing other than...

C430S567000, C430S599000, C430S609000, C430S637000, C430S966000

Reexamination Certificate

active

06280915

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to tabular grain emulsions suitable for use in radiographic elements exhibiting reduced dye stain.
BACKGROUND OF THE INVENTION
Tabular grain emulsions have found a wide acceptance in the art of photography.
Tabular grains are herein defined as grains having two substantially parallel (111) crystal faces, each of which is substantially larger than any other single crystal face of the grain. The aspect ratio, that is the ratio of the diameter to thickness of the tabular grains is substantially greater than two.
In a radiographic element, spectrally sensitized tabular grain emulsions as compared to non-tabular grain emulsions having a comparable speed (sensitivity) and silver coverage, show an improved granularity, an increased silver image covering power especially for strongly hardened layers, a more rapid developability and a decreased dependence of the photographic results on changes of the processing temperature.
Besides these general advantages tabular grain emulsions, coated in double side coated radiographic materials, show an improved speed-cross-over relationship as set forth in U.S. Pat. No. 4,411,986.
Although double side coated radiographic elements containing spectrally sensitized tabular grains have numerous advantages an important disadvantage is met for tabular grains having a mean grain thickness of less than 0.3 &mgr;m in that an increased dye stain of the fully processed radiographic elements can occur. This dye stain is the result of an incomplete removement of the spectral sensitizer during processing. Because of their high surface to volume ratio tabular grains contain significantly higher amounts of spectral sensitizer per volume of silver halide to obtain the optimal sensitivity and thus higher amounts of spectral sensitizer have to be removed.
Particularly with relation to recent trends as shorter processing times to save time, lower regeneration volumes with a composition that is less threatening the environment, it is important to offer suitable films to the customer that are adapted to the new requirements.
Solutions for the increased dye stain after processing have been described e.g. in EP-Application 426 193 and U.S. Pat. No. 4,960,683, wherein thiols, triazolium thiolates, disulphides and thioether compounds have been added to the processing solutions or to the photographic material. The addition of products to the layer(s) of the photographic material that are released during the processing of the said material are described in U.S. Pat. No. 5,108,888.
Another solution is offered by the choice of a spectral sensitizing dye with an adapted structure like benzimidazolo carbocyanines disclosed in EP-A 506 584. Other miscellaneous measures consist e.g. in the addition of very fine high silver iodide crystals to the protective coating capable of being dissolved during fixation as in U.S. Pat. No. 4,520,098.
OBJECT OF THE INVENTION
It is an object of the present invention to provide reduced dye stain in a radiographic material with spectrally sensitized tabular grain emulsions after processing said materials in a rapid processing cycle of less than 60 seconds dry to dry and/or under processing conditions using lower regeneration volumes.
It is a further object of the present invention to provide a material that should be particularly suitable for the said rapid processing cycle with an acceptable dye stain.
Further objects will become apparent from the description hereinafter.
SUMMARY OF THE INVENTION
According to this invention a silver halide coated X-ray photographic material is disclosed comprising exposed spectrally sensitized silver bromide or silver bromoiodide tabular grains having an average thickness of less than 0.30 &mgr;m, in at least one light-sensitive layer and which is characterised in that it further contains in the said light-sensitive layer and/or at least one non-light sensitive layer at least one polyoxyethylene compound comprising from about 20 to 100 mole percent recurring units of the formula (Ia)
and 80 to 0 mole % recurring units of the formula (Ib)
and wherein R represents an aliphatic, aromatic, or heterocyclic group, and X represents a halogen e.g. bromine or chlorine.
DETAILED DESCRIPTION OF THE INVENTION
According to this invention R is preferably selected from the group consisting of alkyl, aralkyl, hydroxyalkyl, alkoxyalkyl, alkylthioalkyl, acyloxyalkyl, cycloalkyl and aryl. Still more preferably R is a alkyl and the number of carbon atoms is from 1 to 5.
Polyethylene oxide compounds carrying thioether groups as substituents on the linear chain are known for accelerating or activating the development of exposed silver halide elements as set forth in U.S. Pat. No. 4,013,471. Said activators can be used in silver complex diffusion transfer processes wherein the alkaline processing solution contains a tertiary alkanolamine and that is free of primary and secondary alkanolamines as has been described in EP-Application 565 152, filed Apr. 10, 1992. Unexpectedly, a long term ambient storage and/or usage of the alkaline solution without loss of overall process quality becomes achievable by applying that invention.
Specific examples of compounds for use according to this invention are given hereinafter (see compounds I.1 to I.3):
In a preferred embodiment 60 to 0 mole % recurring units of the formula (Ib)
and still more preferably only 40 to 0 mole % of the said recurring units are present, whereas preferably from about 40 to 100 mole percent and still more preferably 60 to 100 mole percent recurring units of the formula (Ia)
are present.
According to the present invention the tabular silver bromide or silver bromoiodide grains can be prepared as described by Berry et al in Photographic Science and Engineering, Vol 5, No 6, 1961, by Duffin, Photographic Emulsion Chemistry, Focal Press, 1966, p. 66-72 and by early patent literature including Bogg U.S. Pat. No. 4,063,951, Lewis U.S. Pat. No. 4,067,739 and Maternaghan U.S. Pat. Nos. 4,150,994; 4,184,877 and 4,184,878. However as the tabular grains described therein cannot be regarded as showing a high diameter to thickness ratio, commonly termed aspect ratio, it is more preferable to prepare the silver bromide or silver bromoiodide used in this invention as described in U.S. Pat. No. 4,434,226 (Wilgus et al.) for tabular silver bromoiodide grains having a thickness less than 0.2 &mgr;m, a diameter of at least 0.6 &mgr;m and an average aspect ratio greater than 8:1 and accounting for at least 50 percent of the total projected area of all the emulsion grains; U.S. Pat. No. 4,439,520 (Kofron et al) for similar grains which are spectrally sensitized; U.S. Pat. No. 4,425,425 (Abbott et al) for radiographic materials containing tabular grains with an aspect ratio of at least 8:1 and U.S. Pat. No. 4,425,426 from the same author for similar grains with an aspect ratio between 5:1 and 8:1 as well as the survey on high aspect ratio silver halide emulsions as appeared in Research Disclosure, Volume 225, January 1983, Item 22534. A way can be followed to prepare tabular grains with an increased thickness as described in U.S. Pat. Nos. 4,801,522; 5,028,521 and 5,013,641 making use of ammonia or ammonia generated “in situ”.
In accordance with the present invention a more preferred method for the preparation of an emulsion with tabular silver halide grains, having an average thickness of less than 0.30 &mgr;m and an average aspect ratio of at least 2:1 has been described in EP-Application No. 92.201.259.
For silver bromoiodide crystals it is specifically contemplated to incorporate up to 3 mole percent of iodide ions in the silver halide e.g. silver bromide tabular grains of the present invention. This can be achieved by mixing a soluble bromide and a soluble iodide salt in one or more of the halide solutions up to the desired mole % concentrations required in each preparation step or by a triple jet technique, or separate addition of a iodide containing aqueous solution. Due to the lower solubility of iodide ions in comparison with bromide io

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