Radiation imagery chemistry: process – composition – or product th – Transfer procedure between image and image layer – image... – Diffusion transfer process – element – or identified image...
Reexamination Certificate
2000-05-03
2001-07-17
Schilling, Richard L. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Transfer procedure between image and image layer, image...
Diffusion transfer process, element, or identified image...
C430S204000, C430S227000, C430S517000, C430S519000, C430S606000
Reexamination Certificate
active
06261733
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a silver salt diffusion transfer material suitable for making a printing plate.
More specifically, the present invention relates to a silver salt diffusion transfer material for making a printing plate that is spectrally sensitized for light of about 400 nm.
BACKGROUND OF THE INVENTION
With recent rapid progress of information transmitting systems, silver halide photographic light sensitive materials have been increasingly required to have high sensitivity. Such systems are, for example, high speed phototypesetting systems according to which information output from an electronic computer is immediately displayed as letters or figures by a cathode ray tube and press facsimile systems for rapid transmission of news paper originals to remote places.
Photographic phototype setting materials include photographic films and papers used in a process for preparing a lithographic printing plate and silver salt diffusion transfer, called DTR-based lithographic printing plates disclosed in e.g. U.S. Pat. No. 4,501,811 and U.S. Pat. No. 4,784,933. With the latter materials a lithographic printing plate is immediately obtained without the need of a contact exposure or camera exposure.
Todate on the market phototypesetters usually work with a He/Ne laser (632 nm), a laser diode (680 nm) or LED ( 670 or 780 nm). Especially phototypesetters that operate with a He/Ne laser or LED (670-680 nm) are frequently employed. Since these light sources emit in a very narrow spectral range photographic materials were developed for each of the above mentioned light sources.
A disadvantage of all these materials is that they are sensitive to visible light and have to be treated in a dark room. Recently, there are available lasers which emit in the spectral range of 390-410 nm. Materials, sensitive for said lasers could have the possibility of being treated in subdued yellow light.
However, when said deep blue lasers are used to irradiate an imaging element comprising in the order given on a hydrophilic surface of a support (i) an image receiving layer containing physical development nuclei, (ii) a photosensitive layer containing at least one silver halide emulsion in water permeable relationship with said image receiving layer and spectrally sensitized for said laser, the imaging element can still not be treated under subdued yellow light without an unwanted increase in sensitivity, leading to an irreproducible sensitivity and possibly fog.
OBJECTS OF THE INVENTION
It is an object of the present invention to provide a high speed photographic material that can be imaged using scanning exposure beams with wavelengths in the deep blue i.e. between 390 and 410 nm and that yields printing plates of high contrast and high resolving power.
It is a further object of the present invention to provide a high speed photographic material that can be imaged using scanning exposure beams with wavelengths in the deep blue and that can be treated under subdued yellow light.
It is still a further object of the invention to provide a method for obtaining a lithographic plate with said photographic material.
Further objects of the present invention will become clear from the description hereafter.
SUMMARY OF THE INVENTION
According to the present invention, there is provided a silver salt diffusion transfer material, comprising on a hydrophilic surface of a support in the order given (i) an image receiving layer containing physical development nuclei, (ii) a photosensitive layer containing a silver halide emulsion being in water permeable relationship with said image receiving layer and (iii) a top layer containing gelatin, said silver halide emulsion being spectrally sensitized with a dye with a sensitizing maximum between 380 and 430 nm, characterized in that said top layer comprises a compound I
and/or a compound II
DETAILED DESCRIPTION OF THE INVENTION
Compound I and compound II can be used together but are preferably used separately. The amount of compound I and/or compound II in the top layer ranges preferably from 50 mg/m
2
to 1000 mg/m
2
, more preferably from 100 mg/m
2
to 500 mg/m
2
.
Said silver halide photographic emulsion is spectrally sensitized with spectral sensitizing dyes having preferably their sensitizing maximum in the range between 390 nm and 415 nm. More preferred said spectral sensitizing dyes are compounds corresponding
to the general formulas I, II or III wherein each of Y and Z independently represents O or S, W represents CH or N, T and T′ each represents hydrogen, or one or more substituents selected from the group consisting of alkyl, aryl, aralkyl, alkoxy, halogen, cyano, fused-on ring, R
1
and R
2
each independently represents an alkyl group, preferably methyl or ethyl, R
3
and R
4
each independently represents an alkyl group wherein one of said groups carries an anionic group, R
5
and R
6
each independently represents alkyl groups carrying an acidic group, one of these acid groups being in anionic form, preferably butylsulphonic acid, X
−
represents an anion, e.g. F
−
, Cl
−
, Br
−
, I
−
, toluene sulphonate, triflate, ClO
4
−
etc. . . and M represents a basic group, preferably an ammine group. Most preferred sensitizing dyes are compounds corresponding to formula I. Examples of deep blue sensitizing dyes according to formula I and III are shown in respectively tables 1 and 2.
TABLE 1
Dye I-1
Dye I-2
TABLE 2
Dye III-1
Dye III-2
The spectral sensitizing dye is preferably present in said photographic emulsion in an amount between 0.3 and 3 mmole/mole AgX, more preferably in an amount between 0.5 and 1.5 mmole/mole AgX.
The silver halide emulsion or emulsions according to the invention are substantially free from silver bromide. Substantially free from silver bromide means that said silver halide emulsion or emulsions comprises less than 1 mole % of silver bromide, preferably less than 0.1 mole % of silver bromide, still more preferably less than 0.01 mole % most preferably is totally free from silver bromide.
The silver halide emulsion or emulsions according to the invention preferably comprises a minor amount of silver iodide. A minor amount means between 1 mole % and 0.01 mole %, more preferably between 0.03 and 0.1 mole %. Said iodide is preferably present in the outer sphere of said silver halogenide.
The photosensitive layer used according to the present invention may be any layer comprising a hydrophilic colloid binder and at least one silver halide emulsion, at least one of the silver halide emulsions being photosensitive and all of the silver halide emulsions being substantially free from silver bromide.
The photographic silver halide emulsion(s) used in accordance with the present invention can be prepared from soluble silver salts and soluble halides according to different methods as described e.g. by P. Glafkides in “Chimie et Physique Photographique”, Paul Montel, Paris (1967), by G. F. Duffin in “Photographic Emulsion Chemistry”, The Focal Press, London (1966), and by V. L. Zelikman et al in “Making and Coating Photographic Emulsion”, The Focal Press, London (1966).
Preferably a silver halide emulsion containing at least 99 mole % of silver chloride is used in order to be suitable for treatment in subdued yellow light.
The average size of the silver halide grains may range from 0.10 to 0.70 &mgr;m, preferably from 0.25 to 0.45 &mgr;m.
Preferably during the precipitation stage iridium and/or rhodium containing compounds or a mixture of both are added. The concentration of these added compounds ranges from 10
−8
to 10
−3
mole per mole of AgNO
3
, preferably between 10
−7
and 10
−5
mole per mole of AgNO
3
.
The emulsions can be chemically sensitized e.g. by adding sulphur-containing compounds during the chemical ripening stage e.g. allyl isothiocyanate, allyl thiourea, and sodium thiosulphate. Also reducing agents e.g. the tin compounds described in BE-P-493 464 and 568 687, and polyamines such as diethylene triamine or derivatives of aminomethan
Callant Paul
Coppens Paul
Vervloet Ludo
AGFA-GEVAERT
Breiner & Breiner
Schilling Richard L.
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