Radiation imagery chemistry: process – composition – or product th – Nonradiation sensitive image processing compositions or... – Developer
Reexamination Certificate
1996-01-31
2002-04-30
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Nonradiation sensitive image processing compositions or...
Developer
C430S480000, C430S481000, C430S483000
Reexamination Certificate
active
06379877
ABSTRACT:
1. FIELD OF THE INVENTION
The present invention relates to a developing solution and a method for developing an exposed photographic silver halide material.
2. BACKGROUND OF THE INVENTION
It is known that by processing a silver halide photographic material finely divided metallic silver, so-called silver deposit, is formed in the developer (ref. e.g. Photographic Silver Halide Diffusion Processes by A. Rott and E. Weyde—The Focal Press, (1972), p. 67). The formation of silver deposit is particularly disturbing in automatic processing apparatus wherein it results in deposits of black silver on conveyor and transport rollers and smudging of photographic material conducted therewith.
The formation of silver deposit can be attributed to the presence in conventional developers of silver halide complexing agents like, e.g., sulphite and thiocyanate ions, which are present for stability and speed. In this medium the complex ions formed are effectively reduced to metallic silver nuclei. Growth of said nearly invisible fine nuclei leads to the formation of said silver deposit. As a consequence regularly cleaning of the automatic processing machines is required. When a film is introduced into the processor as first film of a whole series of films, its first contact with the first stained roller releases the deposit from the said roller or disturbs the deposited layer. As a consequence after one rotation of the said roller the unevenly distributed dirt or stain comes into contact again with the transported film surface so that it may be deposited onto said surface. This phenomenon is recurrently repeated, not only at the first roller, but also at the further rollers that are mounted onto the racks and is well-known as “pi-line” defect. The crystalline silver deposit may further cause damaging of the surface of the coated hydrophilic layers on the film and/or cause locally situated pressure phenomena, resulting in “artefacts”, thereby seriously impeding the diagnostic value of the obtained image. Especially when the silver halide photographic material shows processed images with a diagnostic value, like, e.g., in medical imaging or in non-destructive testing, said diagnostic value may be impaired.
Besides the occurrence of this defect in processed materials for radiographic recording and duplicating, it can also be detected at films and papers for general amateur and professional photography, at materials for pre-press graphic arts applications, films for cinematographic recording and printing, materials which after processing can serve as planographic printing plates, microfilm applications, etc.
In order to prevent the formation of silver deposit it has been proposed to add particular compounds to the developer, forming sparingly soluble and non-reducible silver salts, as, e.g., 5,5′-bis-1,2,4-triazoline-3-thiones or derivatives of 1,3,4-thiadiazole-2-thiols as described, e.g. in BE-P 606,550 and GB-P 1,120,963, 2-mercapto-1,3,4-thiadiazoles described in U.S. Pat. No. 3,212,892. A great variety of other mercapto compounds has been described in FR-P 1,470,235 and 1-phenyl-5-mercapto-tetrazole compounds having a —NHX substituent on the phenyl nucleus have been disclosed in GB-P 1,471,554. In the latter document it has been described that the emulsion layer may contain auxiliary coating agents such as saponin, sodium lauryl sulphate, dodecylphenol polyethylene oxide ether and hexadecyltrimethyl ammonium bromide.
The same result can be obtained by the presence in the developer of the fog inhibitor 1-phenyl-5-mercaptotetrazole, but if it is used in an amount higher than necessary for reducing fog in the silver halide photographic material, the sensitivity of the said material is markedly reduced. Such effect is probably due to the penetrating of the 1-phenyl-5-mercaptotetrazole from the developer liquid into the exposed photographic silver halide emulsion layer and its interaction with latent image nuclei. More recently triazolium thiolates for use in the developer have been described in e.g. EP-A 0 533 182.
In EP-Specification 0 223 883 a method to reduce the appearance of silver deposit has been described which comprises the treating of a silver halide photographic material with an aqueous alkaline liquid in the presence of (i) a developing agent, (ii) a heterocyclic mercapto compound including an aliphatic group of at least 3 carbon atoms and (iii) a surface active agent, characterised in that said surface active agent is an anionic alkylphenoxy polyalkyleneoxy phosphate ester surfactant.
In EP-A 0 620 484, reduction of the so-called “pi-line” defect, already mentioned hereinbefore, especially for processed materials for non-destructive testing purposes, has been described. Such materials should comprise at least one vinyl sulphone compound as a hardening agent and at least one polyoxyalkylene compound as a surfactant in at least one of its hydrophilic layers. Combined with a processing method comprising a developing step wherein the developer comprises as a surfactant at least one anionic alkylphenoxy and/or alkoxy polyalkyleneoxy phosphate ester, sulphate ester, alkyl carboxylic, sulphonic or phosphonic acid and/or a salt thereof a remarkable improvement has been obtained. A similar result has been obtained as disclosed in EP-A's 0 621 506 and 0 620 483.
Although said methods to reduce the amount of silver deposit are very effective it is not more than a “treating method” wherein the amount of silver nuclei is not decreased but wherein said nuclei are more “dispersed” and are merely inhibited to grow further to form larger crystalline silver deposits. No “curing” effect in the sense of reducing the generation of nuclei can be obtained with these methods. Moreover the stability of the developer, especially its sensitivity to oxidation by contact with air oxygen, is not improved either.
3. OBJECTS OF THE INVENTION
It is an object of the present invention to provide a stable developer and a method for developing a photographic silver halide material wherein the formation of silver deposit is reduced effectively without adversely affecting photographic speed.
It is a further object of the present invention to provide a suitable sensitometry for the material processed in the developer used according to the method of this invention.
Moreover it is an object to provide a developing method, wherein the developer is stable against oxidation by air oxygen as a low regeneration volume per square unit of the said material should be highly appreciated.
Other objects and advantages of the present invention will become clear from the further description.
4. SUMMARY OF THE INVENTION
It has surprisingly been found now that the objects of the invention can be attained by providing a developer having a low pH value between 9.6 and 11.0, preferably between 9.6 and 10.3, and comprising hydroquinone in an amount from 0 to less than 30 g per liter, an auxiliary developing agent, and as silver halide complexing agents alkali metal sulphite salts, preferably sodium salts, in an amount from 0 to less than 50 g per liter, more preferably to less than 40 g per liter, and thiocyanate salts in amounts from 0.1 to 3 g, more preferably from 0.5 to 2.5 g per liter,
and at least 1 g per liter of a compound corresponding to the formula (I), a precursor thereof, a derivative thereof and/or a metal salt thereof
wherein
each of A, B and D independently represents an oxygen atom or NR
1
;
X represents an oxygen atom, a sulphur atom, NR
2
; CR
3
R
4
; C═O; C═NR
5
or C═S;
Y represents an oxygen atom, a sulphur atom, NR
′2
; CR
′3
R
′4
; C═O; C═NR
′5
or C═S;
Z represents an oxygen atom, a sulphur atom, NR
″2
; CR
″3
R
″4
; C═O; C═NR
″5
or C═S;
n equals 0, 1 or 2;
each of R
1
to R
5
, R
′1
to R
′5
and R
″1
to R
″5
, independently represents hydrogen, subsituted or unsubstituted alkyl, aralkyl, hydroxyalkyl, carboxyalkyl; substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl
Andriessen Hieronymus
Henderickx Freddy
Meeus Pascal
Verbeeck Ann
Agfa-Gevaert
Breiner & Breiner L.L.C.
Le Hoa Van
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