Radiation imagery chemistry: process – composition – or product th – Transfer procedure between image and image layer – image... – Diffusion transfer process – element – or identified image...
Patent
1994-06-03
1996-07-30
Chea, Thorl
Radiation imagery chemistry: process, composition, or product th
Transfer procedure between image and image layer, image...
Diffusion transfer process, element, or identified image...
430204, 430254, 430300, 430309, 430611, 430619, G03C 800
Patent
active
055410340
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a heat-developable silver-based photosensitive imaging element coated from aqueous compositions and to a method for producing a lithographic printing plate in a dry manner by means of said imaging element.
BACKGROUND OF THE INVENTION
Lithography is the process of printing from specially prepared surfaces, some areas of which are capable of accepting lithographic ink, whereas other areas, when moistened with water, will not accept the ink. The areas accepting ink are the printing image areas and the ink-rejecting areas are the background areas.
In the art of photolithography, a photographic material is made image-wise receptive to oily or greasy inks in the photo-exposed (negative-working) or in the non-exposed (positive-working) areas on a hydrophilic background. Common photographic materials employed for making a lithographic printing plate are materials based on a photosensitive polymer or are silver salt diffusion transfer materials.
Silver salt diffusion transfer materials offer the advantage of having a high speed in a broad spectral range, whereas common photosensitive polymer materials are only sensitive to light of a narrow spectral range, commonly between 300 and 500 nm. Furthermore, photosensitive polymers do not offer the speed of a silver halide material.
Silver salt diffusion transfer materials require the use of liquid processing baths. As a consequence, the formation of a lithographic printing plate by means of such materials takes much time and requires much labour. The chemicals used in the wet processing are harmful to the human body and they soil the cloths and hands of the operators.
In GB-P 1,454,271 a method of making a lithographic printing plate in a dry manner has been described, which method comprises image-wise exposing to actinic radiation the sensitive layer of a photosensitive heat-processable photographic material, which layer contains a binder and, as part of an image-forming system, a light-insensitive reducible metal salt of a straight-chain fatty acid having at least 10 carbon atoms, heating the layer to develop a first image therein by reduction of the metal salt and thereby liberate fatty acid, and holding the layer in contact with a receiving sheet e.g. a hydrophilic grained anodized aluminium foil, whilst being held at a temperature above the melting point of the fatty acid so that fatty acid-containing material transfers from the developed areas to the receiving sheet to produce an oleophilic transfer image. However, an important disadvantage is that organic solvents are needed for preparing and coating the photosensitive heat-processable photographic material used according to that method. The use of organic solvents is more expensive than that of aqueous solvents, and moreover, organic solvents may be harmful ecologically.
It is therefore desired that the photosensitive silver-based material be coated from aqueous compositions and that the material be treated in a dry manner without the use of liquid processing solutions.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a heat-developable silver-based photosensitive imaging element coated from aqueous compositions.
It is another object of the present invention to provide a method for producing a lithographic printing plate in a dry manner by means of said heat-developable silver-based photosensitive imaging element.
Further objects of the present invention will become clear from the description hereinafter.
According to the present invention a heat-developable silver-based photosensitive imaging element is provided, which comprises a heat-reducible organic silver salt, a photosensitive silver halide a developing agent, and a releasing compound wherein said releasing compound is capable of information-wise releasing a hydrophobizing agent under the development conditions used for heat-developing exposed silver salts.
The present invention also provides a heat-developable silver-based photosensitive imaging element comprising a
REFERENCES:
patent: 4845018 (1989-07-01), Sato et al.
De Busser Rudi
Leenders Luc
Monbaliu Marcel
Van Cleuvenbergen Rudy
Agfa-Gevaert N.V.
Chea Thorl
LandOfFree
Production of lithographic printing plates in a dry manner does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Production of lithographic printing plates in a dry manner, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Production of lithographic printing plates in a dry manner will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1657416