Radiation imagery chemistry: process – composition – or product th – Silver halide colloid tanning process – composition – or product
Patent
1998-10-29
2000-03-07
Chea, Thorl
Radiation imagery chemistry: process, composition, or product th
Silver halide colloid tanning process, composition, or product
G03C 106
Patent
active
060338253
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a photographic silver halide recording material for producing black and white negatives with ultrahard-gradation contrast which contains a hydrazine compound and a contrast-boosting amino compound.
During photomechanical reproduction, halftone images frequently have to be converted into raster images. This is achieved using silver halide materials which are developed by special processes to ultrahard-gradation contrast, i.e. to a maximum gradation of the characteristic curve higher than 10. Known processes include, for example, the lithographic process employing low-sulphite, formaldehyde-containing hydroquinone developers. Development in the presence of hydrazine compounds has been widely practised in recent times.
With this process, certain amino compounds are frequently used further to boost the contrast. For example, EP-00 32 456-B1 claims a process in which a recording material is processed in the presence of a hydrazine compound with a hydroquinone-3-pyrazolidinone developer containing a contrast-boosting quantity of an amino compound. However, these developers have a number of drawbacks. For some years, therefore, contrast-boosting amino compounds have also been incorporated into the photographic recording material together with hydrazine compounds.
German Offenlegungsschrift DE-A-43 10 327 describes a process for producing negatives with ultrahard-gradation contrast, in which the silver halide recording material is developed in the presence of compounds of which the molecules contain at least one quaternary nitrogen atom and at least one tertiary amine function.
EP-04 73 342-A1 describes a photographic silver halide material which may be developed to ultrahard-gradation contrast in a developer with a pH<11. The light-sensitive coating of this material contains a hydrazine compound having a specific formula as well as an amino or a quaternary onium compound and is adjusted to a pH of at least 5.9.
U.S. Pat. No. 4,975,354 proposes that certain secondary or tertiary amino compounds also containing at least three oxyethylene units in their molecule be incorporated into the silver halide materials as contrast booster in addition to hydrazine compounds.
EP 04 22 677 describes the use of tertiary amino compounds with at least three oxyethylene units in the molecule as development accelerators in developer solutions which also act in the presence of hydrazine compounds.
EP 05 39 998 claims silver halide materials which contain thioether compounds with a tertiary amino group in addition to hydrazine compounds.
Further amino compounds which have a contrast-boosting effect when incorporated with hydrazine compounds are described in EP-A-06 63 611.
Finally, it is also known from U.S. Pat. No. 4,929,535 that certain phosphonium compounds may display a contrast-boosting effect in hydrazine compound-containing silver halide materials.
A drawback frequently observed in known high-contrast recording materials is a pronounced change in the photographic properties during prolonged storage.
The fog increases in particular. The normal precautions against fog, namely the addition of anti-fogging agents to the emulsion and less intensive chemical ripening have resulted in inadequate speed. Furthermore, the normal anti-fogging agents such as benzotriazoles, nitroindazoles and mercaptotetrazoles inhibit infectious development, resulting in unsatisfactory contrast, particularly in the case of high-speed processing which is normal nowadays.
In particular, high-contrast materials for high-speed processing, of which the layers contain only a few gelatins, have a particular type of fog which is described as black or coal dust fog. It differs from the phenomenon known as peppercorn fog in that the blackened regions are smaller and more numerous. On the other hand, these regions are much greater than those which consist only of one respective developed silver halide grain and are characteristic of the known emulsion fog.
A further drawback of these materials is the low acutance of the line and raster i
REFERENCES:
patent: 3043697 (1962-07-01), Foregard et al.
patent: 4929535 (1990-05-01), Takahashi et al.
patent: 4975354 (1990-12-01), Machonkin et al.
patent: 5420004 (1995-05-01), Fujita et al.
Ruger Reinhold
Varescon Fran.cedilla.ois
Agfa-Gevaert NV
Chea Thorl
LandOfFree
Silver-halide recording material to produce negatives with reduc does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Silver-halide recording material to produce negatives with reduc, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Silver-halide recording material to produce negatives with reduc will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-361249