Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Two or more radiation-sensitive layers containing other than...
Reexamination Certificate
1999-09-29
2001-04-17
Schilling, Richard L. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Two or more radiation-sensitive layers containing other than...
C430S531000, C430S536000, C430S537000, C430S961000
Reexamination Certificate
active
06218094
ABSTRACT:
FIELD OF THE INVENTION
The invention is related to a light-sensitive silver halide photographic material having satisfactory developability, reduced pressure sensitivity and excellent surface characteristics after processing in both hardener containing and hardener free processing.
BACKGROUND OF THE INVENTION
Rapid processing becomes more and more important and therefore the thickness of the light-sensitive hydrophilic colloid layers of a photographic film is reduced and the hardening level is increased. However this causes disadvantages related with pressure sensitivity in the dry state before or in the wet state during processing. Scratch formation in the wet state often occurs and a solution for this may be offered by coating a thicker antistress layer with an increased amount of binder e.g. gelatin. Although these increased amounts have the advantage of giving rise to more surface glare after processing, an inadmissable contamination or sludge formation may occur in the processing solutions. Moreover a thicker antistress layer may retard the processing, resulting in a decreased developability, and drying velocity.
It has been established however that if the processing proceeds in developer and fixer solutions containing hardening agents that after treatment with said solutions and rinsing the film material water is spreaded unevenly on the surface of the processed film material. As a consequence unevenly dried water spots remain on the film after the drying step at the end of the processing cycle as so called “water spot defects”.
It has been established otherwise that if the processing proceeds with solutions free from hardening agents problems related with surface characteristics occur as e.g. lack of surface glare and, even more important, unevenness in glare over the processed surface after rapid drying. A solution therefore can be found in EP-A 0 806 705, wherein a method has been disclosed of processing an image-wise exposed light-sensitive silver halide material by the steps of developing, fixing in a fixer solution containing less than 4 g per liter of aluminum ions expressed as an equivalent amount of aluminum sulphate, rinsing and drying; characterized in that said material comprises a support and on one or both sides thereof at least one light-sensitive silver halide emulsion layer and a gelatinous protective antistress layer, wherein said antistress layer comprises at least one polymer latex in such an amount that there is a ratio by weight of latex to gelatin is from 0.5 to 1.5 and wherein said material is hardened to such an extent that its swelling degree after immersing said material for 3 minutes in demineralized water of 25° C. is not more than 300% (a condition which does even not express very high hardening levels). When no aluminum ions are present in the fixer solution as in hardener free processing the problem of “water spot defects” is not as stringent as in the presence thereof.
From practical experience it has been pointed out however that that the presence of a polymer latex in the protective antistress layer in order to avoid uneven surface glare or gloss as set forth in EP-A 0 806 705 leads to lack for developability of the emulsion crystals coated in the light-sensitive silver halide emulsion layer(s) of the silver halide photographic material which causes problems, especially in rapid processing applications.
OBJECTS OF THE INVENTION
Therefore it is a first object of the present invention to provide a light-sensitive silver halide photographic material having satisfactory surface characteristics, particularly reflected in the absence of “water spot defects” due to uneven drying in the processing cycle of automatic processors (in rapid processing cycles from 90 as well as from 45 seconds) and even in manual processing conditions.
It is still a further object of the present invention that all measures taken in order to promote excellent surface characteristics of the film material mentioned hereinbefore lay no burden on the developability (sensitometric properties especially reflected by speed and contrast) of the silver halide emulsion crystals coated in the light-sensitive layer(s) of the said material, especially in the short developing times provided in rapid processing cycles.
Other objects will become apparent from the description hereinafter.
SUMMARY OF THE INVENTION
The above mentioned objects are realized by providing a light-sensitive silver halide photographic material comprising a support and on one or both sides thereof at least one light-sensitive silver halide emulsion layer, a gelatinous protective antistress layer and, adjacent thereto as an outermost layer, a gelatinous afterlayer characterized in that said afterlayer comprises at least one polymer latex, being a polybutylacrylate, a polybutylmethacrylate latex or a polyurethane latex, or a copolymer latex being a copolymer poly(butyl methacrylate) polyacrylamide N-substituted sulfo-isobutyl salt, in a ratio amount by weight of (co)polymer latex to gelatin from 0.2:1 up to 5:1 and a total amount of (co)polymer latex and gelatin of at least 0.10 g/m
2
.
Specific features for preferred embodiments of the invention are disclosed in the dependent claims.
Further advantages and embodiments of the present invention will become apparent from the following description.
DETAILED DESCRIPTION OF THE INVENTION
Preferred (co)polymer latices used in the protective antistress layer and/or outermost afterlayer of the light-sensitive silver halide material according to the present invention are cross-linked polymers and can be prepared as described e.g. in U.S. Pat. No. 4,301,240 by emulsion polymerisation of aliphatic esters of acrylic and/or methacrylic acid in water in the presence of polyfunctional cross-linking monomers and an emulsifier, followed by saponification of the obtained copolymer. By said emulsion polymerisation copolymers with a molecular weight well above 500,000 are obtained and the average particle size of the latex is smaller than 150 nm. Another example of the synthesis of ionic cross-linked copolymers can further be found e.g. in EP-A 0 452 568 and the corresponding U.S. Pat. No. 5,472,832.
In photographic material of the present invention a particularly preferred latex of an ionic copolymer for use in the gelatinous protective antistress layer of a light-sensitive silver halide material is a copolymer of butyl methacrylate and acrylamide-N-isobutylsulphonic acid sodium salt as represented in the formula (I).
In one embodiment in the copolymer according to the formula (I) suitable for use in the material according to the present invention a ratio amount of butylmethacrylate and and acrylamide-N-isobutyl-sulphonic acid sodium salt is at least 80:20 and more preferably about 95:5.
Other preferred latex compounds are polybutylacrylate and polybutylmethacrylate as examples of non-ionic polymer latex compounds. It is not excluded to use them in combination, e.g. in a mixture with each other or even with other polymers dispersed as a latex as there are polymethylmethacrylate, polymethylacrylate, polyethylacrylate latex compounds and the like. Average particle sizes of the latex particles are in the range from about 50 nm up to about 115 nm as for the latex copolymer according to the formula (I) given hereinbefore.
Another particularly preferred latex is a polyurethane latex, which is preferably in the form of a dispersion of an aliphatic anionic polyurethane. In praxis the commercially available product IMPRANIL 43056, trademarked product from BAYER AG, Leverkusen, Federal Republic of Germany is very suitable. This IMPRANIL-latex is a 40% aqueous dispersion of polyurethane prepared from DESMODUR W (trademarked product from BAYER AG), which is a dicyclohexylmethane diisocyanate, and a polyester having a low molecular weight of about 800. The average particle size of the latex may vary between 0.02 and 0.2 &mgr;m The polyurethane is added to the coating solution as an aqueous latex dispersion. An especially useful polyurethane is the one having a high procentual amount of uret
den Zegel Marc Van
Louwet Frank
Michiels Eddy
Vandenabeele Hubert
AGFA-GEVAERT
Breiner & Breiner
Schilling Richard L.
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