Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
1999-10-13
2001-07-24
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S523000, C430S533000, C430S948000
Reexamination Certificate
active
06265143
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an improved photographic material of the Lippmann emulsion type for industrial applications.
BACKGROUND OF THE INVENTION
So-called Lippmann emulsions having an average grain size of less than 0.1 &mgr;m (100 nm) are of particular importance for the preparation of photographic plates or films with high resolution for use in microphotography, for recording nucleophysical phenomena, for the preparation of masks in the production of microelectronic integrated circuits, for use in holography, for high density storage, etc.
In the production of microelectronic integrated circuits drawings are made, optionally on a highly enlarged scale, of the various successive masks necessary to produce one integrated circuit whereupon the drawings are reduced, if necessary in successive steps, and reproduced on a photographic plate or film material forming thereby the mask ready for use. By various photographic and and chemical steps (photo-etching of laquered plates) the images of the masks thus produced are transferred to the surface on which the integrated circuit is to be made, in order to produce the required circuit elements. In recent times several of the preliminary steps are reproduced digitally.
The photographic materials for use in the production of masks as described above should have a high resolving power and acutance and allow a correct reproduction of the dimensions of the image. Unless the dimensional reproduction is kept within the accepted tolerances the maks will be useless because it will not enable electronic components to be formed in the circuitry with the required degree of accuracy. Developments in the field of computer and telecommunication systems create the need for ever increasing packing densities on the circuit elements and therefore it has become common practice to reproduce image details e.g. lines and slits having widths even smaller than the emulsion thickness e.g. smaller than 5 &mgr;m. These image details should be reproduced within the accepted width tolerances of at most 10% respective to the original width.
Old patents dealing with the type of material described above are e.g. U.S. Pat. Nos. 3,652,280, 4,148,647, 4,108,661, and DE 2002062.
Materials and corresponding processing chemicals usable in the applications as explained above are marketed by Agfa-Gevaert N.V. under the trade name MILLIMASK.
Now recently new applications for this type of material have been invented by us that pose high requirements to the material concerning resistance to mechanical and thermal deformation. This is the case when the material is used under so-called “heavy duty” circumstances such as high temperature, extreme humidity, fast changes in temperature or humidity, or high mechanical stress. Under these circumstances the conventional supports for this type of material such as glass or polyethylene terephthalate and acrylic plates behave unsatisfactory.
OBJECTS OF THE INVENTION
It is an object of the present invention to provide a Lippman-type photographic material with improved dimensional stability under heavy duty circumstances such as high temperature, extreme humidity, fast changes in temperature or humidity, or high mechanical stress.
It is a further object of the present invention to provide new applications for this type of material.
SUMMARY OF THE INVENTION
The objects of the present invention are realized by providing a photographic material comprising a transparent polycarbonate support and at least one silver halide emulsion layer comprising a Lippmann emulsion having an average grain size smaller than 0.1 &mgr;m.
DETAILED DESCRIPTION OF THE INVENTION
In a most preferred embodiment the polycarbonate film used as support is the aromatic polycarbonate based on bisphenol A as recurring unit. This is the world-wide most used polycarbonate film for industrial applications. This type of polycarbonate film shows following excellent physical and mechanical characteristics which make it most suitable as support for the photographic materials of the present invention:
good machinability: cutting (band or circular sawing, drilling, turning, routing, tapping, threading, . . .
excellent optical transmission properties:
light transmission: 90%
haze: 0.5%
refractive index: 1.586
temperature behaviour:
coefficient of thermal expansion: 70 &mgr;m/m° C.
heath conductivity: 0.20 W/m° C.
i.e. polycarbonate adapts fast (in minutes) to temperature changes;
humidity behaviour:
coefficient of relative humidity expansion: about 0 &mgr;m/m % RH;
water absorption after 24 h: 0.035%
water absorption after 7 days: 0.35%
polycarbonate adapts slowly (several days) to relative humidity changes;
specific gravity: 1.20×10
3
kg/m
3
;
tensile heat distortion at 50 psi: 134° C. or higher for particular types;
i.e. PC can be used in heavy duty circumstances;
printing possible;
cementing possible;
image protection: waxing or lamination.
Polycarbonate film can be manufactured in several thicknesses. For use in connection with the present invention thicknesses of 400 &mgr;m or of 1.5 mm are preferred depending on the particular application.
For use in the present invention the polycarbonate film is preferably provided with a subbing layer. An example of a suitable subbing layer is based on a combination of colloidal silica, gelatin and resorcine.
The halide composition of the silver halide Lippmann emulsions used in accordance with the present invention is not specifically limited and may be any composition selected from e.g. silver chloride, silver bromide, silver iodide, silver chlorobromide, silver bromoiodide, and silver chlorobromoiodide. In a prefered embodiment however the Lippmann emusion is a iodobromo emulsion containing at least 90% of bromide. In the most preferred embodiment the emulsion consists of 97% of bromide and 3% of iodide.
The photographic emulsion(s) can be prepared from soluble silver salts and soluble halides according to different methods as described e.g. by P. Glafkidès 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). They can be prepared by mixing the halide and silver solutions in partially or fully controlled conditions of temperature, concentrations, sequence of addition, and rates of addition. The silver halide can be precipitated according to the single-jet method, the double-jet method, the conversion method or an alternation of these different methods.
The emulsion can be desalted in the usual ways e.g. by dialysis, by flocculation and re-dispersing, or by ultrafiltration.
The light-sensitive silver halide emulsions are preferably chemically sensitized as described e.g. in the above-mentioned “Chimie et Physique Photographique” by P. Glafkidès, in the above-mentioned “Photographic Emulsion Chemistry” by G. F. Duffin, in the above-mentioned “Making and Coating Photographic Emulsion” by V. L. Zelikman et al, and in “Die Grundlagen der Photographischen Prozesse mit Silberhalogeniden” edited by H. Frieser and published by Akademische Verlagsgesellschaft (1968). As described in said literature chemical sensitization can be carried out by effecting the ripening in the presence of small amounts of compounds containing sulphur e.g. thiosulphate, thiocyanate, thioureas, sulphites, mercapto compounds, and rhodamines. The emulsions can be sensitized also by means of gold-sulphur ripeners, gold-selenium ripeners or by means of reductors e.g. tin compounds as described in GB 789,823, amines, hydrazine derivatives, formamidine-sulphinic acids, and silane compounds. Chemical sensitization can also be performed with small amounts of Ir, Rh, Ru, Pb, Cd, Hg, Tl, Pd, Pt, or Au. One of these chemical sensitization methods or a combination thereof can be used.
The light-sensitive silver halide emulsions can be spectrally sensitized with proper dyes such as those described by F. M. Hamer in “The Cyanine Dyes and Related
Janssens Eric René
Peeters Gustaaf Joannes
AGFA-GEVAERT
Baxter Janet
Guy Joseph T.
Hardaway/Mann IP Group
Walke Amanda C.
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