Light-sensitive silver halide radiographic film material having satisfactory antistatic properties during handling

A silver halide photographic material has been provided, having in a layer arrangement at one or both sides of a subbed support, corresponding with a single-side coated or a double-side coated material respectively, one or more layer(s) comprising a light-sensitive silver halide emulsion, one or more protective antistress layer(s) and, optionally, an outermost afterlayer, wherein at least one of said layers, subbing layer(s) inclusive, further comprises means in order to provide, when conditioned at a relative humidity of at most 30%, an electrical resistance, measured as described in Research Disclosure June 1992, item 33840, of from 4.times.10.sup.9 .OMEGA./sq. up to 5.times.10.sup.10 .OMEGA./sq. for the layer having the lowest resistance.

FIELD OF THE INVENTION
 The present invention relates to a radiographic light-sensitive silver
 halide film material having improved antistatic properties.
 BACKGROUND OF THE INVENTION
 It is known that hydrophobic resin sheet and web materials of low
 conductivity readily become electrostatically charged by frictional
 contact with other elements during their manufacture, e.g. during coating
 or cutting, and during use, e.g. during the recording of information in
 exposure devices. Since radiographic film materials, those used for
 medical diagnostic purposes as well as those used for non-destructive
 testing methods, have a hydrophobic resin as a support it is no wonder
 that transport problems tend to occur in the exposure devices as well as
 in the processors wherein after loading the film into the processor the
 film runs into a developer station, a fixer station, optionally rinsing
 stations inbetween and always after said fixer station, followed by
 drying.
 In order to prevent such web materials from being electrostatically charged
 the "tribo-electrical behaviour" of the said web material has been
 optimized (e.g. versus polymethylmethacrylate as a reference polymer) in
 that differences with respect to the said tribo-electrical behaviour
 between said web material and materials with which contact is made during
 further handling (especially before, during and after exposure and before
 processing) are minimized. Useful compounds added to the layers coated
 onto the resin sheet or web material are e.g. polyoxyethylene compounds,
 whether or not combined with surfactants having fluoride substituents as
 has e.g. been described in EP-A's 0 191 491, 0 245 090, 0 260 593, 0 319
 951, 0 320 962, 0 370 404, 0 534 006, 0 633 496 and 0 644 454, and in U.S.
 Pat. Nos. 4,229,524; 4,367,283; 4,388,402; 4,582,781; 4,649,102;
 4,916,054; 5,098,821; 5,258,276 and 5,561,032.
 Such combination of antistatic agents may provide a so-called "lateral
 electrical surface resistivity" of about 10.sup.12 .OMEGA./square,
 measured at a relative humidity of 30%. The said materials are said to
 provide "non-permanent antistatic properties" due to their "ionic
 conductivity". More recently "permanent antistatic properties" have been
 attained for materials by provision of "electronic conductivity", thereby
 reducing the said "lateral electrical resistance" to a value of about
 10.sup.6 .OMEGA./square. Such a relatively low resistance has been
 obtained, particularly in the presence of electronically conducting
 polymers as e.g. polyethylene dioxythiophene, described in EP-A's 0 253
 594,0 292 905, 0 339 340, 0 348 961, 0 440 957, 0 505 955, 0 530 849,0 553
 502, 0 554 588, 0 564 911, 0 570 795, 0 593 111, 0 602 713 and 0 628 560,
 and in U.S. Pat. Nos. 5,279,768; 5,213,714 and 5,306,443.
 In most cases the thiophene compounds are comprised in one or more subbing
 layers of the materials. By reducing the lateral electrical resistance of
 the light-sensitive silver halide photographic material the positive or
 negative charges generated after e.g. friction with another material (e.g.
 inlet in a processing machine) are non-locally distributed over the whole
 material making decrease the charge density, whereby local concentrations
 of electrostatic charges are avoided. Moreover it is possible that
 electrical charges may flow back after interrupting contact with
 electrically conducting materials. It is clear that such low electrical
 surface resistivity is highly appreciated.
 The said "antistatic layers" may be subbing layers, providing adhesion
 between the web sheet and the other layers to be coated thereon, wherein
 said subbing layers are normally coated at both sides of the said web
 sheet or support. The materials having light-sensitive silver halide
 emulsion layers at one or both sides of the subbed supports are said to be
 "single-side" or "double -side" coated respectively.
 In case of a single-side coated material the compounds providing antistatic
 properties may be added to the backing layer(s). Other layers containing
 antistatic agents and coated onto the subbing layers may be an
 intermediate gelatinous layer, whether or not containing filter dyes in
 favour of sharpness, one or more emulsion layers coated adjacent to each
 other, one or more protective antistress layers and, optionally, an
 afterlayer. "Handling film materials" should be understood as "loading
 cassettes" with e.g. radiological films in intensifying screen/film sytems
 as well as recording films in laser devices for recording digitally stored
 information on a hard-copy material, which may cause electrostatic
 phenomena such as "electrostatic sticking" to occur, as well as
 electrostatic charging or discharging.
 Effects of handling caused by electrostatical phenomena can be visually
 observed on the images obtained after processing of e.g. radiographic film
 materials which have been run in some processing devices: it has been
 established that undesired "sparks" are occurring in form of a black line,
 thereby disturbing the diagnostic value of the image, even when the
 electrical surface resistance is as low as 10.sup.6 .OMEGA./sq.,
 especially at low relative humidity of about 30%. This is the case with
 e.g. the trademarked radiographic materials Curix Ortho HTG and Curix
 Ortho HTL from Agfa-Gevaert N.V., Mortsel, Belgium. It is believed that
 those spark discharges, are generated by charge transport from
 electrostatic charges with which an operator is loaded, who brings an
 unprocessed film material to a processing machine that is connected to the
 ground: charges are conducted from the operator, through the film after
 making contact with metal surfaces making part of the said processing
 machine and further to the ground. The same phenomena may appear in an
 apparatus wherein metallic parts have been mounted so that they are
 isolated from the rest of the apparatus and when said metallic parts bear
 accumulated charges: a discharge may take place through the film, over the
 operator and further to the earth. As a result "strikes" or "sparks" in
 form of black lines are found on the film after processing whereby the
 diagnostic value of the film is highly disturbed.
 OBJECTS OF THE INVENTION
 It is an object of the present invention to provide a light-sensitive
 silver halide photographic material for diagnostic imaging in medical as
 well as in non-destructive testing applications, wherein said film has
 such antistatic properties that spark discharges are avoided, in
 particular when loading said film material into a processing machine.
 It is a further object of the present invention to provide a method of
 formation of a diagnostic image by means of the said materials.
 Further advantages and embodiments of the present invention will become
 apparent from the following description.
 SUMMARY OF THE INVENTION
 The objects of the present invention are realized by providing a silver
 halide photographic material comprising at one or both sides of a subbed
 support, corresponding with a single-side coated or a double-side coated
 material respectively, one or more layer(s) comprising a light-sensitive
 silver halide emulsion, one or more protective antistress layer(s) and,
 optionally, an outermost afterlayer, wherein at least one of said layers,
 subbing layer(s) inclusive, further comprises means in order to provide,
 when conditioned at a relative humidity of at most 30%, an electrical
 resistance, measured as described in Research Disclosure June 1992, item
 33840, of from 4.times.10.sup.9 .OMEGA./sq. up to 5.times.10.sup.10
 .OMEGA./sq. for the layer having the lowest resistance, more preferably
 from 1.times.10.sup.10 .OMEGA./sq. up to 5.times.10.sup.10 .OMEGA./ sq.
 and still more preferably up to 2.times.10.sup.10 .OMEGA./sq., even at a
 relative humidity of 30% or lower, thanks to the presence of a conductive
 compound, preferably a polythiophene derivative, and most preferably
 polyethylene dioxythiophene (PEDT).
 This compound is preferably incorporated in the antistatic layer coated
 upon the subbing layer, making part of the subbing layer unit, wherein
 said subbing layer unit is in direct contact with the support and wherein
 said polyethylene dioxythiophene in the said antistatic layer is present
 as an aqueous dispersion containing a polymeric anion, more preferably
 polystyrene sulphonate.
 An image forming method for the formation of a radiographic diagnostic
 image has further been provided, said method comprising the step of
 exposing image-wise by laser irradiation or by X-ray irradiation said
 materials, followed by processing by the steps of developing, fixing,
 rinsing and drying.

An isolated and loaded operator causing electrostatic discharge (occurring
 as "line discharges" on the film material after processing) is represented
 by a loaded capacitor plate having a capacity C=300 pF. Contact has been
 made between plate A of said capacitor (loaded up to a capacity of 300 pF)
 and a film material sample F without making contact with any other subject
 (by hanging up the film material sample F in an isolating frame FR). The
 other capacitor plate B, without making contact with the earth, was loaded
 up to -2 kV (corresponding with a discharge energy of about 2.4 mJoule).
 After having no charging current anymore, contact with the source of high
 voltage has been broken. In capactor C between plates A and B dielectric
 medium DM is present.
 In order to simulate the metal inlet of a processing machine a metal bar M
 having a relatively sharp edge (representing the inlet of the earthed
 processing machine) has been provided in order to make contact with the
 (thereby discharged) film material F.
 DETAILED DESCRIPTION OF THE INVENTION
 It has been found unexpectedly that, in order to avoid a failure in form of
 a black line hindering an unambiguous diagnosis from a processed recording
 film material after processing said material in certain film processors,
 that it is of utmost importance that the layer in the layer arrangement of
 said film material having the lowest resistance (or the highest
 conductivity) is characterized by a resistance, even at a relative
 humidity of 30% or lower, having a value of from 4.times.10.sup.9
 .OMEGA./sq. up to 5.times.10.sup.10 .OMEGA./ sq. for the layer having the
 lowest resistance, when measured according to the method described in
 Research Disclosure June 1992, item 33840. More preferably this resistance
 should have a value of from 1.times.10.sup.10 .OMEGA./sq. up to
 5.times.10.sup.10 .OMEGA./sq. and even more preferably up to
 2.times.10.sup.10 .OMEGA./sq. Values of the said resistance outside these
 barriers, thus lower than 4.times.10.sup.9 .OMEGA./sq. or higher than
 5.times.10.sup.10 .OMEGA./sq., give rise to the problems of spark
 discharges as set forth hereinbefore.
 As explained above, in a preferred embodiment at least one of the
 antistatic layers being a light-sensitive silver halide emulsion, a
 protective antistress layer and/or an--optionally present--after-layer
 contain(s) a conductive compound the nature of which will now be explained
 in detail.
 Such a compound can show ionic or electronic conductivity. Ionic conducting
 compounds are e.g. high molecular weight polymeric compounds having ionic
 groups, e.g. carboxylic sodium salt groups, built in at frequent intervals
 in the polymer chain [ref. Photographic Emulsion Chemistry, by G. F.
 Duffin,--The Focal Press--London and New York (1966)--Focal Press Ltd., p.
 168]. In order to further enhance the permanence of the conductivity of
 ionic conductive polymers it has been proposed to cross-link these
 polymers with hydrophobic polymers as has been illustrated in U.S. Pat.
 Nos. 4,585,730; 4,701,403; 4,589,570; 5,045,441 and in EP-A's 0 391 402
 and 0 420 226. The conductivity however of an antistatic layer containing
 said ionic conductive polymers, even after cross-linking, is dependent on
 moisture, quantitatively expressed as the relative humidity.
 Therefore electronically-conducting conjugated polymers have been developed
 that have electronic conductivity. Representatives of such polymers have
 been described in the periodical Materials & Design, Vol. 11, No. 3--June
 1990, p. 142-152, and in the book "Science and Applications of Conducting
 Polymers"--Papers from the 6th European Physical Society Industrial
 Workshop held in Lothus, Norway, 28-31 May 1990, Edited by W R Salaneck
 Linkoping University, D T Clark ICI Wilton Materials Research Centre, and
 E J Samuelson University of Trondheim, published under the Adam Hilger
 imprint by IOP Publishing Ltd Techno House, Redcliffe Way, Bristol BS1
 6NX, England. Substances having electronic conductivity instead of ionic
 conductivity have a conductivity that is independent from moisture. The
 said substances, being conductive compounds, are particularly suited for
 use in the production of antistatic layers with permanent and, especially
 preferred as in the present invention, reproducibly controlled
 conductivity.
 According to the present invention said conductive compound is a
 (co)polymer compound selected from the group consisting of a polymer with
 acidic groups optionally further crosslinked by aziridines; a mixture of
 water-soluble conductive polymers, containing sulphonic acid groups,
 sulphuric acid groups or carboxylic acid groups together with a
 hydrophobic polymer and a crosslinking or curing agent, a
 (poly)phosphazene, a graft polymer of polyphosphazenes with polyalkylene
 glycols; (co)polymers of a diallyldialkylammonium salt; polyalkyleneimine
 grafted vinyl polymers; a copolymer of styrene sulphonic acid and a
 hydroxyl group containing monomer crosslinked by methoxyalkylmelamine; the
 said copolymer of styrene sulphonic acid but crosslinked by a hydrolyzed
 metal lower alkoxide; polymer complexes containing polyalkylene oxide
 units; a combination of polymerized oxyalkylene oxide units and a fluorine
 containing inorganic salt; a polyoxyalkylene in combination with a
 thiocyanate, iodide, perchlorate, or periodate; a highly crosslinked
 vinylbenzyl quaternary ammonium polymer in combination with a hydrophobic
 binder; a sulphonated anionic microgel latex, polymers and copolymers of
 pyrrole, furan, aniline, vinylcarbazole and pyridine and their
 derivatives, tetracyanoquinone (TCNQ) complex and polyarenemethylidenes
 and derivatives thereof.
 Many of the known electronically conductive polymers among them are highly
 colored which makes them less suited for use in photographic materials of
 to the present invention, but some of them of the group of the
 polyarenemethylidenes, as e.g. polythiophenes and polyisothianaphthenes
 are not prohibitively colored and transparent, at least when coated in
 thin layers. As a result thereof polythiophene derivatives are a preferred
 type of conductive compounds for use in the materials of the present
 invention.
 The production of conductive polythiophenes has been described in
 preparation literature mentioned in the above mentioned book "Science and
 Applications of Conducting Polymers", p. 92.
 For ecological reasons the coating of antistatic layers should proceed,
 where possible, from aqueous solutions by using organic solvents in
 amounts as low as possible. The production of antistatic coatings from
 aqueous coating compositions being dispersions of polythiophenes in the
 presence of polyanions has described in EP-A 0 440 957. Thanks to the
 presence of the polyanion the polythiophene compound is kept in
 dispersion.
 Preferably said polythiophene has thiophene nuclei substituted with at
 least one alkoxy group, or --O(CH.sub.2 CH.sub.2 O).sub.n CH.sub.3 group,
 n being an integer having a value from 1 to 4, or, most preferably,
 thiophene nuclei that are ring closed over two oxygen atoms with an
 alkylene group including such group in substituted form.
 Preferred polythiophenes for use in materials according to the present
 invention are made up of structural units corresponding to the following
 general formula (I):
 ##STR1##
 in which
 each of R.sup.1 and R.sup.2 independently represents hydrogen or a
 C.sub.1-4 alkyl group or together represent an optionally substituted
 C.sub.1-4 alkylene group or a cycloalkylene group, preferably an ethylene
 group, an optionally alkyl-substituted methylene group, an optionally
 C.sub.1-12 alkyl- or phenyl-substituted 1,2-ethylene group, a
 1,3-propylene group or a 1,2-cyclohexylene group.
 The most preferred compound however is poly(3,4-ethylenedioxythiophene),
 (PEDT) with following formula (II):
 ##STR2##
 The preparation of said polythiophene and of aqueous polythiophenepolymeric
 polyanion dispersions containing said polythiophene has been described
 EP-A 0 440 957, cited above. The synthesis proceeds, in the presence of
 said polymeric polyanion compounds, by oxidative polymerization of
 3,4-dialkoxythiophenes or 3,4-alkylenedioxythiophenes according to the
 following general formula (III) :
 ##STR3##
 wherein:
 R.sup.1 and R.sup.2 are as defined in general formula (I), with oxidizing
 agents typically used for the oxidative polymerization of pyrrole and/or
 with oxygen or air in the presence of said polyacids, preferably in
 aqueous medium containing optionally a certain amount of organic solvents,
 at temperatures of 0 to 100.degree. C.
 The polythiophenes get positive charges by the oxidative polymerization.
 The location and number of said charges cannot be determined with
 certainty and therefore they are not mentioned in the general formula of
 the repeating units of the polythiophene polymer.
 The size of polymer particles in the coating dispersion is in the range of
 from 5 nm to 1 .mu.m, preferably in the range of 40 to 400 nm.
 Suitable polymeric polyanion compounds required for keeping said
 polythiophenes in dispersion are provided by acidic polymers in free acid
 or neutralized form. The acidic polymers are preferably polymeric
 carboxylic or sulphonic acids. Examples of such polymeric acids are
 polymers containing repeating units selected from the group consisting of
 acrylic acid, methacrylic acid, maleic acid, vinyl sulfonic acid and
 styrene sulfonic acid or mixtures thereof.
 The anionic acidic polymers used in conjunction with the dispersed
 polythiophene polymer have preferably a content of anionic groups of more
 than 2% by weight with respect to said polymer compounds to ensure
 sufficient stability of the dispersion. Suitable acidic polymers or
 corresponding salts have been described e.g. in DE-A's 25 41 230, 25 41
 274 and 28 35 856, in EP-A's 0 014 921 0 069 671 and 0 130 115, and in
 U.S. Pat. Nos. 4,147,550; 4,388,403 and 5,006,451.
 The polymeric polyanion compounds may consist of straight-chain, branched
 chain or crosslinked polymers. Cross-linked polymeric polyanion compounds
 with a high amount of acidic groups are swellable in water and are named
 microgels. Such microgels have been disclosed e.g. in U.S. Pat. Nos.
 4,301,240, 4,677,050 and 4,147,550.
 The molecular weight of the polymeric polyanion compounds being polyacids
 is preferably in the range from 1,000 to 2,000,000 and more preferably in
 the range from 2,000 to 500,000. Polyacids within the above criteria are
 commercially available, for example polystyrene sulfonic acids and
 polyacrylic acids, or may be produced by known methods (ref. e.g.
 Houben-Weyl, Methoden der Organischen Chemie, Vol. E20, Makromolekulare
 Stoffe, Teil 2, (1987), pp. 141 et seq.).
 Instead of the free polymeric polyacids applied in conjunction with the
 polythiophenes it is possible to use mixtures of alkali salts of said
 polyacids and non-neutralized polyacids, optionally in the presence of
 monoacids. Free acid groups of the polyanionic polymer may be allowed to
 react with an inorganic base, as with sodium hydroxide, in order to obtain
 a neutral polymer dispersion before coating.
 The weight ratio of polythiophene polymer to polymeric polyanion
 compound(s) can vary widely, for example from about 50/50 to 15/85. The
 most preferred polymeric polyanion for use in combination with the
 polythiophene derivative used in materials according to the present
 invention, e.g. PEDT, is polystyrene sulphonate (PSS).
 Besides the first embodiment described hereinbefore wherein the conductive
 compound is a polythiophene derivative in another embodiment a conductive
 compound providing the desired resistance when measured by the method
 described in Research Disclosure June 1992, item 33840, is a metal oxide
 compound, said metal being selected from the group consisting of tin,
 indium tin, vanadium, zinc, manganese, titan, indium, silicium, magnesium,
 barium, molybdene and tungsten. Said metal oxides, such as vanadium
 pentoxide, as disclosed e.g. in WO 91/02289, U.S. Pat. No. 5,221,598; ZnO,
 SnO.sub.2, MgO, as disclosed in e.g. U.S. Pat. No. 5,238,801, colloidal
 manganese dioxide as disclosed in EP-A 0 504 826; oxides from Zn, Ti, In,
 Si, Mg, Ba, Mo, W, V, as disclosed in EP-A 0 569 821; in combination with
 a fluorine containing (co)polymer according to EP-A 0 552 617, a reaction
 product of a metal oxide sol and a chitosan salt as in EP-A 0 531 006;
 heteropolycondensates of tin and boron oxide as described in WO 90/013851;
 doped metal oxides; silica and modified silica compounds, as in U.S. Pat.
 Nos. 4,895,792; 5,385,986 and 5,236,818; EP-A's 0 334 400, EP-A 0 438 621,
 EP-A 0 296 656 and EP-A 0 444 326, conductive polymers with acidic groups
 optionally further crosslinked e.g. by aziridines or other compounds, such
 as those disclosed in U.S. Pat. Nos. 4,960,687; 4,891,308; 5,077,185 and
 5,128,233; in EP-A's 0 318 909, 0 439 181, 0 486 982 and 0 505 626 and in
 DE-A 41 03 437; mixtures of a water-soluble conductive polymer, containing
 e.g. sulphonic acid groups, sulphuric acid groups or carboxylic acid
 groups and in addition thereto a hydrophobic polymer and a crosslinking or
 curing agent as disclosed e.g. in U.S. Pat. Nos. 5,013,637; 5,079,136;
 5,098,822; 5,135,843 and EP-A's 0 432 654, 0 409 665 and 0 391 402;
 (poly)phosphazene derivatives, as described in U.S. Pat. Nos. 4,948,720
 and 4,898,808 and in WO 90/08978; graft polymers of polyphosphazenes with
 polyalkylene glycols as disclosed in EP-A 0 304 296; (co)polymers of a
 diallyldialkylammonium salt as disclosed in EP-A 0 320 692,
 polyalkyleneimine grafted vinyl polymers such as disclosed in U.S. Pat.
 No. 5,153,115, copolymer of styrene sulphonic acid and a hydroxyl group
 containing monomer crosslinked by methoxyalkylmelamine as described in WO
 91/18061, the same copolymer but crosslinked by a hydrolyzed metal lower
 alkoxide as disclosed in WO 91/18062; polymer complexes containing
 polyalkylene oxide units as disclosed in JP-A 62/286038; a combination of
 polymerized oxyalkylene oxide units and a fluorine containing inorganic
 salt as disclosed in EP-A 0 170 529; a polyoxyalkylene in combination with
 a thiocyanate, iodide, perchlorate, or periodate as in U.S. Pat. No.
 4,272,616; a highly crosslinked vinylbenzyl quaternary ammonium polymer in
 combination with a hydrophobic binder as described in Research Disclosure,
 June 1977, Item 15840 and U.S. Pat. No. 3,958,995; sulphonated anionic
 microgel latices as described in Research Disclosure, October 1977, Item
 16258; polymers and copolymers of pyrrole, furan, aniline, vinylcarbazole,
 pyridine, and other heterocycles and their derivatives as disclosed in
 several patents, usually outside the scope of imaging science, as in
 EP-A's 0 537 504, 0 326 864, 0 264 786, 0 259 813, 0 195 381 and 0 469
 667; in DE-A's 39 40 187, 37 43 519, 37 34 749 and 37 16 284 and in WO
 96/01480; and so-called TCNQ-complexes as e.g.
 N-butyl-isochinolinium-tetracyanoquinone-dimethane. References with
 respect to TCNQ-complexes can be found in "Handbook of organic conductive
 molecules and polymers", Vol. 1, Chapter 4, p. 229, and in J. Am. Chem.
 Soc., Vol. 84, (162) p. 3370.
 In a further embodiment of the present invention in said material said
 conductive compound is a mixture of different types of conductive
 compounds, mentioned hereinbefore.
 In a more preferred embodiment in the material according to the present
 invention said conductive compound is thus a polythiophene compound
 present as an aqueous dispersion of a polythiophene compound/polymeric
 anion complex, incorporated in a layer or layers providing antistatic
 properties as in one or more optionally present afterlayers and/or in a
 subbing layer unit, more preferably in a layer coated upon the subbing
 layer in direct contact with the support.
 In a still more preferred embodiment in the material according to the
 present invention said polymeric anion is polystyrene sulphonate and in
 the most preferred embodiment said polythiophene compound is polyethylene
 dioxythiophene (PEDT).
 Apart from being rendered antistatic by the presence of a conductive
 compound the outermost layer(s) can be made antistatic by adding a
 compound or mixtures of compounds which reduce the so-called triboelectric
 chargeability of the layer. Usually one of these compounds is a
 perfluorated surfactant. The triboelectric chargeability of a layer versus
 a reference material is expressed as its Q.sub.Far value which is
 determined as follows. The experimental mounting consists of two
 concentric cylinders isolated from each other. The external cylinder is
 connected to the earth potential and the internal cylinder, functioning as
 cage of Faraday, is connected to an electrometer. The internal cylinder
 contains a flat metal plate to which a 275.times.35 mm strip of the sample
 to be measured is applied. A 60.times.35 strip of the reference material
 (e.g. the backing layer of CURIX HT.RTM., trademarked product from
 Agfa-Gevaert N.V.) is applied to a PTFE-block (polytetrafluor-ethylene, a
 strong insulator) of dimensions 55.times.30.times.15 mm. Materials and
 test equipment are conditioned for at least 24 hours in a room with fixed
 temperature and relative humidity conditions. After discharging of the
 whole the block is put in the Faraday cage. The triboelectric charge is
 generated by rubbing the PTFE-block containing the reference sample under
 its own weight (0.53 N) over the metal plate containing the sample to be
 measured. The block is moved five times there and back at an average speed
 of 10 cm/s. Then the reference material is removed from the inner cylinder
 and the countercharge is measured. An average (median) of twenty repeated
 measurements is calculated. It was found experimentally that in order to
 avoid problems with static charging a Q.sub.Far value not surpassing
 3.6.times.10.sup.-6 C/m.sup.2 could be allowed for an outermost layer.
 Materials and methods wherein a material is made antistatic by reducing
 its triboelectric chargeability are disclosed in e.g. U.S. Pat. Nos.
 3,775,126 and 3,850,640; disclosing a combination of a cationic
 perfluorinated alkyl surfactant and a non-ionic alkyl phenoxy
 polypropylene oxide surfactant; U.S. Pat. No. 3,850,642 wherein the
 surface layer contains a so-called "charge control agent"; GB-A 1,330,356
 wherein a fluoro-substituted quaternary ammonium compound is combined with
 another wetting agent; U.S. Pat. No. 4,956,270 describing the combination
 of an organic fluoro compound and a non-ionic surfactant; EP-A 0 288 059
 disclosing particular compounds containing polyalkylene groups; EP-A 0 319
 951 and U.S. Pat. No. 5,258,276 combining an anionic, a non-ionic and a
 fluorinated non-ionic surfactant; and EP-A 0 534 006 combining a
 polyalkylene compound and a fluorinated surfactant containing oxyethylene
 groups.
 Apart from the conductive compound or the compounds reducing the
 triboelectric position the antistatic layers can contain several other
 types of ingredients. So a matting agent, also called roughening agent or
 spacing agent, may be present. This roughening agent can be chosen from a
 wide variety of chemical classes and commercial products provided the
 particles chosen show an excellent mechanical and thermal stability.
 Preferred roughening agents include following :
 the spherical polymeric beads disclosed in U.S. Pat. No. 4,861,818;
 the alkali-soluble beads of U.S. Pat. No. 4,906,560 and EP-A 0 584 407;
 the insoluble polymeric beads disclosed in EP-A 0 466 982;
 polymethylmethacrylate beads;
 copolymers of methacrylic acid with methyl- or ethylmethacrylate;
 TOSPEARL siloxane particles (e.g. types T105, T108, T103, T120), marketed
 by Toshiba Co;
 SEAHOSTAR polysiloxane--silica particles (e.g. type KE-P50), marketed by
 Nippon Shokubai Co;
 ROPAQUE particles, being polymeric hollow spherical core/sheat beads,
 marketed by Rohm and Haas Co, and described e.g. in U.S. Pat. Nos.
 4,427,836, 4,468,498 and 4,469,825;
 ABD PULVER, marketed by BASF AG
 CHEMIPEARL, spherical poymeric particles, marketed by Misui Petrochemical
 Industries, Ltd.
 The spacing particles must be chosen so that they are not optically
 disturbing.
 In a most preferred embodiment the roughening agent is based on polymethyl
 methacrylate beads which are preferably cross-linked. They preferably have
 an average particle size of 0.5 to 5 .mu.m, and most preferably 1 to 4
 .mu.m. Other preferred roughening agents are disclosed in EP-A's 0 080
 225, 0 466 982, and 0 698 625. Furtheron, the antistatic layer(s) may
 contain an adhesion promoting agent, preferably a (co)polymer with
 hydrophilic groups (see example section furtheron), and a so-called
 anti-scratch agent, e.g. a polysiloxane-polyether copolymer.
 The different other layers and sheets constituting the recording material
 of the present invention, apart from the antistatic layers, will be
 explained now in more detail. A common support of a photographic silver
 halide emulsion material is a hydrophobic resin support or hydrophobic
 resin coated paper support. Useful transparent polymeric supports include
 e.g. cellulose nitrate film, cellulose acetate film, polyvinylacetal film,
 polystyrene film, polyethylene terephthalate film, polyethylene
 naphthalate film, polycarbonate film, polyvinylchloride film or
 poly-.alpha.-olefin films such as polyethylene, polynaphthalene or
 polypropylene film. Hydrophobic resin supports are well known to those
 skilled in the art and are made e.g. of polyester, polystyrene, polyvinyl
 chloride, polycarbonate, preference being given to polyethylene
 terephthalate and polyethylene naphthalate. Hydrophobic resin supports of
 the materials according to the present invention are further provided with
 one or more subbing layers known to those skilled in the art for adhering
 thereto a hydrophilic colloid layer, as described e.g. for polyethylene
 terephthalate in U.S. Pat. Nos. 3,397,988, 3,649,336, 4,123,278 and
 4,478,907, wherein in said subbing layers the conductive compound
 providing low lateral surface resisitivity as desired is incorporated. The
 thickness of such organic resin film is preferably comprised between 0.03
 and 0.35 mm. In a most preferred embodiment of the present invention the
 support is a polyethylene terephthalate layer provided with a subbing
 layer. This subbing layer can be applied before or after stretching of the
 polyester film support. The polyester film support is preferably biaxially
 stretched at an elevated temperature of e.g. 70-120.degree. C., reducing
 its thickness by about 1/2 to 1/9 or more and increasing its area 2 to 9
 times. The stretching may be accomplished in two stages, transversal and
 longitudinal in either order or simultaneously. The subbing layer is
 preferably applied by aqueous coating between the longitudinal and
 transversal stretch, in a thickness of 0.1 to 5 .mu.m. In case of a
 bismuth recording layer the subbing layer preferably contains a
 homopolymer or copolymer of a monomer comprising covalently bound chlorine
 as described in EP-A 0 464 906. Examples of said homopolymers or
 copolymers suitable for use in the subbing layer are e.g. polyvinyl
 chloride, polyvinylidene chloride, a copolymer of vinylidene chloride, an
 acrylic ester and itaconic acid, a copolymer of vinyl chloride and
 vinylidene chloride, a copolymer of vinyl chloride and vinyl acetate, a
 copolymer of butylacrylate, vinyl acetate and vinyl chloride or vinylidene
 chloride, a copolymer of vinyl chloride, vinylidene chloride and itaconic
 acid, a copolymer of vinyl chloride, vinyl acetate and vinyl alcohol etc..
 Polymers that are water dispersable are preferred since they allow aqueous
 coating of subbing layers which is in favour of ecology.
 Suitable coating agents for layers building-up the material according to
 the present invention include non-ionic agents such as saponins, alkylene
 oxides as e.g. polyethylene glycol, polyethylene glycol/polypropylene
 glycol condensation products, polyethylene glycol alkyl esters or
 polyethylene glycol alkylaryl esters, polyethylene glycol esters,
 polyethylene glycol sorbitan esters, polyalkylene glycol alkylamines or
 alkylamides, silicone-polyethylene oxide adducts, glycidol derivaties,
 fatty acid esters of polyhydric alcohols and alkyl esters of saccharides;
 anionic agents comprising an acid group such as a carboxy, sulpho,
 phospho, sulphuric or phosphoric ester group; ampholytic agents such as
 aminoacids, aminoalkyl sulphonic acids, aminoalkyl sulphates or
 phosphates, alkyl betaines, and amine-N-oxides; and cationic agents such
 as aklylamine salts, aliphatic, aromatic, or heterocyclic quaternary
 ammonium salts, aliphatic or heterocyclic ring-containing phosphonium or
 sulphonium salts. Other suitable surfactants include perfluorinated
 compounds.
 The silver halide photographic material according to the present invention
 thus preferably contains the conductive compound providing the desired
 resistance for the layer showing the best conductivity, wherein said
 silver halide photographic material comprises a subbed support and at one
 or both sides thereof, corresponding with a single-side coated or a
 double-side coated material respectively, at least one layer comprising
 one or more light-sensitive silver halide emulsion, a protective
 antistress layer and, optionally, an afterlayer, wherein at least one of
 said layers, subbing layer(s) inclusive, contains said conductive
 compound.
 In the antistress layer(s) from the materials according to the present
 invention latex-type polymers or copolymers may be included, besides
 hydrophilic colloid binders, wherein those polymers or copolymers are
 chosen in order to be mixed homogeneously therewith. Proteinaceous
 colloids, e.g. gelatin, polysaccharide, and synthetic substitutes for
 gelatin as e.g. polyvinyl alcohol, poly-N-vinyl pyrrolidone, polyvinyl
 imidazole, polyvinyl pyrazole, polyacrylamide, polyacrylic acid, and
 derivatives thereof can be used therefore. Furthermore the use of mixtures
 of said hydrophilic colloids is not excluded. Among these binders the most
 preferred is gelatin. Conventional lime-treated or acid treated gelatin
 can be used. The preparation of such gelatin types has been described in
 e.g. "The Science and Technology of Gelatin", edited by A. G. Ward and A.
 Courts, Academic Press 1977, page 295 and next pages. The gelatin can also
 be an enzyme-treated gelatin as described in Bull. Soc. Sci. Phot. Japan,
 No 16, page 30 (1966). In order to minimize the amount of gelatin, however
 can be replaced in part or integrally by synthetic polymers as cited
 hereinbefore or by natural or semi-synthetic polymers. Natural substitutes
 for gelatin are e.g. other proteins such as zein, albumin and casein,
 cellulose, saccharides, starch, whether or not in oxidized form, and
 alginates. Semi-synthetic substitutes for gelatin are modified natural
 products as e.g. gelatin derivatives obtained by conversion of gelatin
 with alkylating or acylating agents or by grafting of polymerizable
 monomers on gelatin, and cellulose derivatives such as hydroxyalkyl
 cellulose, carboxymethyl cellulose, phthaloyl cellulose, cellulose
 sulphates, etc.. Cross-linked copolymers may be applied, and when applied
 preferable amounts are at least 10% by weight versus the amount of
 hydrophilic colloid present in the antistress layer or layers. In addition
 the said copolymers may be present in an optionally present outermost
 gelatin free coating applied thereover.
 In the material according to the present invention a preferred protective
 antistress layer is made from gelatin hardened up to a degree
 corresponding with a water absorption of less than 2.5 grams of water per
 m.sup.2 and more preferably of at most 1 gram per m.sup.2. The gelatin
 coverage in the protective layer is preferably not higher than about 1.20
 g per sq.m and is more preferably in the range of 0.60 to 1.20 g per sq.m.
 Gelatin in the antistress layer may partially be replaced by colloidal
 silica as it gives rise to a further improvement of the obtained
 properties according to the present invention. Preferably colloidal silica
 having an average particle size not larger than 10 nm and with a surface
 area of at least 300 sq.m. per gram is used, the colloidal silica being
 present at a coverage of at least 50 mg per m2. Further the coverage of
 said colloidal silica in the antistress layer is preferably in the range
 of 50 mg to 500 mg per m.sup.2. Particularly good results which are fully
 in accordance with the present invention are obtained by using a
 protective antistatic layer comprising besides the conductive compound as
 claimed, at least 50% by weight of colloidal silica versus the said
 conductive compound. Especially preferred colloidal silica particles have
 a surface area of 500 m.sup.2 per gram and an average grain size smaller
 than 7 nm. Such type of silica is sold under the name KIESELSOL 500
 (KIESELSOL is a registered trade name of Bayer AG, Leverkusen, Germany).
 In admixture with the hardened gelatin the antistress layer may further
 contain friction-lowering substance(s) such as dispersed wax particles
 (carnaubawax or montanwax) or polyethylene particles, fluorinated polymer
 particles, silicon polymer particles etc. in order to further reduce the
 sticking tendency of the layer especially in an atmosphere of high
 relative humidity.
 The gelatin binder can be forehardened with appropriate hardening agents
 such as those of the epoxide type, those of the ethylenimine type, those
 of the vinylsulfone type e.g. 1,3-vinylsulphonyl-2-propanol, chromium
 salts e.g. chromium acetate and chromium alum, aldehydes e.g.
 formaldehyde, glyoxal, and glutaraldehyde, N-methylol compounds e.g.
 dimethylolurea and methyloldimethylhydantoin, dioxan derivatives e.g.
 2,3-dihydroxy-dioxan, active vinyl compounds e.g.
 1,3,5-triacryloyl-hexahydro-s-triazine, active halogen compounds e.g.
 2,4-dichloro-6-hydroxy-s-triazine, and mucohalogenic acids e.g.
 mucochloric acid and mucophenoxychloric acid. These hardeners can be used
 alone or in combination. The binder can also be hardened with
 fast-reacting hardeners such as carbamoylpyridinium salts as disclosed in
 U.S. Pat. No. 4,063,952 and with the onium compounds as disclosed in EP-A
 0 408 143.
 Besides said conductive compounds providing the desired lateral electrical
 surface resistivity ionic or non-ionic polymers or copolymeric
 combinations of monomers cited hereinbefore are optionally added to
 non-ionic surfactants having antistatic characteristics that is(are)
 present in the outermost layer, optionally present at side of the support
 where the light-sensitive emulsion layer(s) has(have) been coated. As
 non-ionic surfactant(s) having antistatic characteristics any of the
 generally known polyalkylene oxide polymers are useful as antistatic
 agent. Suitable examples of alkylene oxides are e.g. polyethylene glycol,
 polyethylene glycol/polypropylene glycol condensation products,
 polyethylene glycol alkyl ethers or polyethylene glycol alkylaryl ethers,
 polyethylene glycol esters, polyethylene glycol sorbitan esters,
 polyalkylene glycol alkylamines or alkylamides, silicone-polyethylene
 oxide adducts, glycidol derivatives, fatty acid esters of polyhydric
 alcohols and alkyl esters of saccharides.
 In one embodiment the material of the present invention has as an outermost
 coating a protective antistress layer at the silver halide emulsion layer
 side or sides of the photographic silver halide emulsion layer material of
 the present invention, wherein said material is single-side or double side
 coated. In another embodiment the protective antistress layer is covered
 with a gelatin free antistatic afterlayer containing a conductive compound
 as required in at least one of the layers of the material according to the
 present invention. The coating of the said gelatin free antistatic layer,
 as well as the coating of the antistress layer may proceed by any coating
 technique known in the art, e.g. by doctor blade coating, air knife
 coating, curtain coating, slide hopper coating or meniscus coating, which
 are coating techniques known from the production of photographic silver
 emulsion layer materials. Moreover the spray coating technique, known from
 U.S. Pat. No. 4,218,533, may be applied. Any thickening agent may be used
 in order to regulate the viscosity of the solution used for any of the
 said coating techniques provided that they do not particularly affect the
 photographic characteristics of the silver halide light-sensitive
 photographic material. Preferred thickening agents include aqueous
 polymers such as polystyrene sulphonic acid, sulphuric acid esters,
 polysaccharides, polymers having a sulphonic acid group, a carboxylic acid
 group or a phosphoric acid group, polyacrylamide, polymethacrylic acid or
 its salt, copolymers from acrylamide and methacrylic acid and salts
 derived thereof, copolymers from 2-acrylamido-2-methyl-propansulphonic
 acid, polyvinyl alcohol, alginate, xanthane, carraghenan and the like.
 Polymeric thickeners well-known from the literature resulting in
 thickening of the coating solution may be used independently or in
 combination. Patents concerning thickening agents which can be used in the
 layers of the material acccording to the present invention are U.S. Pat
 No. 3,167,410, Belgian Patent No. 558 143, JP-A's 53-18687 and 58-36768,
 DE-A 38 36 945 and EP-A's 0 644 456 and 0 813 105. The gelatin-free
 antistatic afterlayer, if present as outermost layer of the material
 according to the present invention may further comprise spacing agents and
 coating aids such as wetting agents as e.g. :perfluorinated surfactants.
 Spacing agents which may also be present in the protective antistress
 layer in generally have an average particle size which is comprised
 between 0.2 and 10 .mu.m. Spacing agents can be soluble or insoluble in
 alkali. Alkali-insoluble spacing agents usually remain permanently in the
 photographic element, whereas alkali-soluble spacing agents usually are
 removed therefrom in an alkaline processing bath. Suitable spacing agents
 can be made i.a. of polymethyl methacrylate, of copolymers of acrylic acid
 and methyl methacrylate, and of hydroxypropylmethyl cellulose
 hexahydrophthalate. Other suitable spacing agents have been described in
 U.S. Pat. No. 4,614,708. Presence of at least one ionic or non-ionic
 polymer or copolymer latex in the protective antistress coating, and,
 optionally, in the afterlayer coated thereover, moreover provides the
 preservation of good antistatic properties of the material. Moreover the
 absence of water spot defects for the dry film after processing can be
 observed as has been described in EP-A's 0 644 454 and 0 644 456 as well
 as the appearance of an improved surface glare as has been described in
 the same EP-A's and in EP-A 0 806 705 and in EP-Application No. 98203412,
 filed Oct. 8, 1998. Even for thin coated layers for applications in rapid
 processing conditions the same advantages can be recognized. Furthermore
 the appearance of sludge in the processing is significantly reduced as
 well in hardener free as in hardener containing processing solutions.
 Photographic silver halide emulsion materials according to the present
 invention are preferably used in radiography as the said materials as
 claimed hereinafter offer a solution for the problems as set forth in the
 background of the present invention. Single-side coated materials, as
 recording materials in mammographic applications (see e.g. EP-A's 0 610
 609, 0 712 036, 0 874 275) in contact with an intensifying screen at the
 side of the film support having the light-sensitive emulsion layer(s) or
 in laser recording applications as e.g. described in EP-A 0 610 608 and 0
 794 456 for the registration of digitally stored images, thus comprise a
 support and on one side thereof at least one silver halide emulsion layer
 and a protective gelatin antistress layer and, optionally, an outermost
 coating on the said side, whereas on the other side a backing layer is
 preferably present comprising e.g. one or more antihalation dyes which can
 be present either in the said outermost coating or in an underlying back
 coating or in both of them, thereby providing an improved image quality,
 especially sharpness. Antihalation dyes as mentioned are non-spectrally
 sensitizing dyes which are widely used in photographic elements to absorb
 reflected and scattered light. Examples of the said dyes have been
 described e.g. in U.S. Pat. Nos. 3,560,214 and 4,857,446 and in EP-A's 0
 587 229 and 0 587 230. The filter or accutance dye(s) can be coated in
 layers of photographic elements in the form as has been described in
 EP-A's 0 384 633, 0 323 729, 0 274 723, 0 276 566, 0 351 593; in U.S. Pat.
 Nos. 4,900,653; 4,904,565; 4,949,654; 4,940,654; 4,948,717; 4,988,611 and
 4,803,150; in Research Disclosure Item 19551 (July 1980); in EP-A 0 401
 709 and in U.S. Pat. No. 2,527,583, these examples however being not
 limitative.
 Double-side coated materials used in combination with intensifying screens
 in order to detect luminescent radiation generated from the phosphors
 absorbing X-rays as in medical X-ray applications or from direct X-rays as
 in non-destructive applications (see e.g. EP-A 0 890 875), wherein direct
 X-rays may be intensified and filtered by lead screens (see e.g. EP-A 0
 603 431), thus comprise a support and on both sides thereof at least one
 silver halide emulsion layer and a protective gelatin antistress layer
 and, optionally, an outermost coating on the said both sides, wherein
 filter or accutance dyes mentioned hereinbefore can, in order to reduce
 cross-over as in the case of intensifying screen/film combinations, be
 present in the subbing layers, in a hydrophilic (gelatinous) layer between
 said subbing layers and a light-sensitive emulsion layer, in said emulsion
 layers (which may be coated as single emulsion layers or in two or more
 layers adjacent to each other) or even in the protective antistress layer
 or layers. Patents related therewith are EP-A's 0 592 724, 0 603 431, 0
 678 772 and 0 790 526 and EP-Application No 98200061, filed Jan. 13, 1998.
 Light-sensitive silver halide emulsions coated in one or more layers at
 both sides of the subbed support may be the same or different, which means
 that the same or differing silver halide emulsions may be coated wherein
 differences are related with differences in silver halide composition (as
 e.g. silver bromide, silver bromoiodide, silver chlorobromide, silver
 chlorobromoiodide, silver chloride, silver chloroiodide, silver
 chlorobromoiodide) and/or emulsion crystal habit (irregular or regular,
 being cubic, octahedral, {111} or {100} tabular, etc.), differences in
 mean crystal diameter, in monodispersity or heterodispersity of the
 emulsion distribution, differences in chemical sensitization and/or in
 spectral sensitization. In case of differences at both sides of the
 support, films are called "asymmetrical", whereas otherwise they are
 called "symmetrical". Also screens held in contact at both sides of the
 film material during exposure of the films with X-rays may be the same or
 different, wherein differences may be related with the presence of
 different phosphors, providing luminescent radiation of a different
 wavelength at differing sides of the film.
 According to the present invention, a method is further provided for the
 formation of a diagnostic image comprising the step of exposing image-wise
 by laser irradiation a single-side coated material or exposing image-wise
 by X-ray irradiation a double-side coated material according to the
 present invention as described hereinbefore, said exposure step followed
 by processing said material by the steps of developing, fixing, rinsing
 and drying. A method for processing in a short total processing time of 60
 seconds or less of forehardened materials with a developer comprising
 dihydroxybenzenes has e.g. been described in EP-A 0 731 382. Developers
 comprising ascorbic acids or derivatives thereof which are very suitable
 for use in the development method of the materials of the present
 invention have been described e.g. in EP-A 's 0 731 381, 0 731 382 and 0
 732 619.
 A method of processing suitable for processing materials of the present
 invention in a vertical processing apparatus, however not being limited
 thereto in the present invention, has been described in EP-Application No.
 96201753, filed Jun. 24, 1996. Further processing methods have been
 disclosed extensively in EP-A's 0 851 282 and 0 851 286 (especially with
 respect to replenishment of the fixer solution), in EP-Application No.
 97203096, filed Oct. 6, 1997 (with respect to fixation in a fixer
 containing hardening agents, with less sludge formation), in
 EP-Application No. 98200319, filed Feb. 3, 1998 (with respect to ecology,
 thereby leaving less silver in the rinsing water), in EP-Application No.
 98201862, filed Jun. 5, 1998 (with respect to low replenishment amounts
 with low buffering capacity) and in EP-Application No. 98203412, filed
 Oct. 8, 1998 (with respect to excellent surface characteristics of the
 processed material, in processing solutions free from hardening agents and
 containing hardening agents as well).
 By using a recording material having a composition according to the present
 invention problems as preservation of antistatic characteristics before
 processing, water spot defects, sticking and insufficient glare after
 processing in automatic processing machines can be avoided or
 substantially reduced. This means for example that the formation of static
 charges by contact of a silver halide emulsion layer side with the rear
 side of the recording material or caused by friction with substances such
 as rubber and hydrophobic polymeric binder, e.g. the binder constituent of
 phosphor screens used as X-ray intensifying screens, can be markedly
 reduced by employing the present antistatic layer in the layer arrangement
 of the film material according to the present invention. The building up
 of static charges and subsequent dust attraction and/or sparking, e.g.
 during loading of films in cassettes, e.g. X-ray cassettes, or in cameras,
 or during the taking or projection of a sequence of pictures as occurs in
 automatic cameras or film projectors is prevented.
 The following examples illustrate the present invention without however
 limiting it thereto.
 EXAMPLE
 Preparation of Materials Nos. 1-3
 PEDT Containing Subbed Support
 On a web made of blue tinted longitudinally stretched polyethylene
 terephthalate having a thickness of approximately 610 .mu.m was deposited,
 at both sides, following coating composition (given per liter of coating
 solution):
 450 ml of demineralized water;
 260 ml (30%, expressed as weight/volume unit) of a latex of ternary
 co-polymer being co(vinylidene chloride/methyl acrylate/itaconic acid) in
 a procentual weight ratio amount of 88/10/2;
 91 ml (30%, expressed as weight/volume unit) of a latex of ternary
 co-polymer being co(butadiene/methyl acrylate/itaconic acid) in a
 procentual weight ratio amount of 47.5/47.5/5;
 5 ml of concentrated ammonium hydroxide;
 5.8 ml of an aqueous solution (50%, expressed as weight/volume unit) of
 melamine-formaldehyde derivative "Parez Resin 707"
 5 ml of Kieselsol 100 F.TM., trademark product from Bayer AG, Leverkusen,
 Germany.
 190 ml of a solution containing per liter of said solution
 600 ml of demineralized water;
 7.44 g of NaOH;
 47.2 g of sulfosalicylic acid sodium salt;
 260 ml ethanol
 4.4 g of HOSTA BV
 40 g of floroglucin
 7.76 g of AKYPO OP 80
 32.8 g of sorbitol
 40.8 g of 1,2-propanediol
 Said coating composition was applied on both sides of said support by
 air-knife coating, at a coverage of 130 sq.m./liter. The layer was dried
 in hot air stream whereafter the film was stretched transversally to 3.5
 times its original width in a tenter frame in order to get a final film
 thickness of about 175 .mu.m. The film was then heat-set while being kept
 under tension at a temperature of 190.degree. C. for about 20 seconds.
 After heat-setting the film coated with this subbing layer at both sides
 thereof was cooled and further coated with following Compositions A, B and
 C as a first layer in contact with the subbed support layer for the
 Materials A, B and C respectively and Composition C as a second layer for
 the Materials A and B respectively (no second layer for Material C):
 Composition A
 500 ml of said coating composition A are containing:
 447.5 ml of demineralized water;
 5.8 ml of latex B (addition copolymer of vinylidene chloride,
 methylacrylate and itaconic acid, containing 88% by weight of vinylidene
 chloride units, 10% by weight of methylacrylate units, and 2% by weight of
 itaconic acid units was prepared as a latex by classical emulsion
 polymerisation conducted in aqueous medium in the presence of persulphate
 as initiator; concentration expressed as weight per volume unit: 30%).
 43.8 ml of a dispersion of poly(3,4-ethylenedioxy-thiophene)/polyanion
 prepared before as follows:
 Into 1000 ml of an aqueous solution of 20 g of polystyrene sulfonic acid
 (109 mmol of SO.sub.3 H groups) with number-average molecular weight (Mn)
 40,000, were introduced 12.9 g of potassium peroxidisulfate (K.sub.2
 S.sub.2 O.sub.8), 0.1 g of Fe.sub.2 (SO.sub.4).sub.3 and 2.8 g of
 3,4-ethylenedioxy-thiophene. The thus obtained reaction mixture was
 stirred for 24 h at 20.degree. C. and subjected to desalting.
 500 ml of the above prepared reaction mixture were diluted with 500 ml of
 water and stirred for 6 hours at room temperature in the presence of a
 granulated weak basic ion exchange resin LEWATIT H 600 (tradename of Bayer
 AG) and strongly acidic ion exchanger LEWATIT S 100 (tradename of Bayer
 AG. After said treatment the ion exchange resins were filtered off and the
 potassium ion and sulfate ion content were measured which were
 respectively 0.4 g K.sup.+ and 0.1 g (SO.sub.4).sup.2- per liter.
 1.25 ml of N-methylpyrrolidone;
 1.7 ml UVON (=10% solution, expressed as weight per volume unit, of
 ULTRAVON W in a solution of demineralized water/ethanol 80/20). Coating
 composition A was coated at both sides of the subbed support described
 hereinbefore in an amount in order to coat 35 sq.m./liter as first layers
 of Material A coated upon the subbed support described hereinbefore.
 Drying was performed during 1 minute at 120.degree. C.
 Composition B
 500 ml of said coating composition B are containing:
 482 ml of demineralized water;
 5.8 ml of latex B (same as in composition A, given hereinbefore)
 8.75 ml of a dispersion of poly(3,4-ethylenedioxy-thiophene)/polyanion
 prepared as given hereinbefore (composition A)
 1.25 ml of N-methylpyrrolidone;
 1.7 ml UVON (=10% solution, expressed as weight per volume unit, of
 ULTRAVON W in a solution of demineralized water/ethanol 80/20).
 Coating composition B was coated at both sides of the subbed support
 described hereinbefore in an amount in order to coat 35 sq.m./liter as
 first layers of Material B coated upon the subbed support described
 hereinbefore. Drying was performed during 1 minute at 120.degree. C.
 Composition C
 1000 ml of said coating composition C are containing:
 978 ml of demineralized water;
 5.7 g of gelatin Koepff K16353 (manufactured by Koepff, Heilbronn,
 Germany),
 14.2 ml of Kieselsol 300 F (trademarked product from BAYER AG, Leverkusen,
 Germany)
 0.15 ml of polymethyl methacrylate matting agent (diameter:2.5 .mu.m;
 concentration 20%, expressed in weight ratio per volume unit);
 10 ml of solution, the composition (per liter) of which is given
 hereinafter:
 940 ml of demineralized water;
 20 g of ULTRAVON W;
 10 g of ARKO N060;
 33.3 g of hexylene glycol;
 16.6 g trimethylol propane.
 Coating composition C was coated at both sides of the subbed support
 described hereinbefore in an amount in order to coat 35 sq.m./liter as
 first layers of Material C coated upon the subbed support described
 hereinbefore.
 As a second layer for Materials A and B, coated upon the first layers as
 indicated hereinbefore, composition C was coated. No second layer was
 coated for Material C.
 Double side coated X-ray photographic materials Nos 1-3 were provided by
 subsequently coating at both sides on the Materials A, B and C a silver
 halide emulsion layer, a protective antistress layer and a gelatin free
 outermost afterlayer on top. Use was therefore made of the slide hopper
 coating technique for simultaneous application of the emulsion layer, the
 antistress layer and the outermost afterlayer at both sides of the coating
 Materials A, B and C, the composition of which has been given in the Table
 1.
 Preparation Method of the Photographic Material
 A photographic material was prepared composed of
 a subbed polyester base (175 .mu.m thick);
 an emulsion layer comprising a mixture of two gelatinous silver halide
 emulsions (preparation described hereinafter) of which the silver halide
 consists for 99 mole % of silver bromide and 1 mole % of silver iodide
 having a .+-.111} tabular crystal habit;
 a protective antistress layer having the composition given hereinafter.
 an afterlayer as an outermost layer (in the examples where it applies)
 The emulsion layer was containing a light-sensitive tabular silver
 bromoiodide emulsion, the preparation of which has been described
 hereinafter, starting from following solutions (held at 55.degree. C.):
 solution 1: 1.96 molar of an aqueous silver nitrate solution. solution 2:
 1.96 molar of an aqueous potassium bromide solution, solution 3: mixture
 containing 1.93 molar of an aqueous potassium bromide solution and 0.03
 molar of an aqueous potassium iodide solution.
 Following preparation steps were performed in order to precipitate the
 tabular emulsion crystals:
 Nucleation Step
 28 ml of solutions 1 and 2 were introduced into a reaction vessel in 28
 seconds using the double jet technique. Said reaction vessel initially
 contained 2.127 liter of destined water at 45.degree. C., 10.6 grams of
 potassium bromide and 6 grams of inert gelatin and was held at 55.degree.
 C. After one minute the reaction temperature of this mixture was raised to
 70.degree. C. in 20 minutes and 47.5 grams of phthalated gelatin in 475 ml
 destilled water were added. After 10 minutes the neutralization step was
 started. During nucleation the stirring velocity in the reaction vessel
 was held at 150 rpm.
 Neutralization Step
 21.25 ml of solution 1 were added to the reaction vessel at a rate of 7.5
 ml per minute to reach a UAg value (potential versus silver/silver
 chloride reference electrode) of +10 mV, whereafter the first growth step
 was started.
 First Growth Step
 A double jet precipitation was started using solutions 1 and 2: during 1
 minute solution 1 was added at a flow rate of 7.5 ml per minute, while
 solution 2 was added at a rate of 7.7 ml/min., meanwhile maintaining the
 UAg value at +10 mV. The double jet precipitation continued for 31 min. 30
 seconds at a flow rate while increasing the rate of solution 1 up to 22.2
 ml per minute and solution 2 up to 22.6 ml per minute, meanwhile
 maintaining the UAg value at +10 mV again. Thereafter the second
 neutralization phase was started.
 Second Neutralization Step
 26.25 ml of solution 1 was added at a rate of 7.5 ml per minute in 3 min.
 30 seconds so that a UAg value of +100 mV was obtained. The precipitation
 was then continued by a second growth step.
 Second Growth Step
 During 30 seconds solution 1 was injected in the reaction vessel at a flow
 rate of 7.5 ml per minute, while solution 3 was injected at the same flow
 rate. After increasing the stirring velocity up to 550 rpm during 30
 seconds, the flow rates were increased during 41 minutes and 50 seconds up
 to 37.5 ml per minute, meanwhile maintaining a UAg value in the reaction
 vessel of +100 mV. The stirring velocity was decreased from 550 to 250
 rpm.
 The tabular grains of the emulsion thus obtained had the following
 characteristics, measured with electron microscopic techniques:
 average equivalent circular diameter (ECD): 1.04 .mu.m
 coefficient of variation of the tabular grains on ECD: 0.30
 average thickness: 0.22 .mu.m
 average aspect ratio: 4.8
 percentage of total projective surface: 93%.
 Washing and Dispersing Procedure
 After the emulsion precitation was ended the pH value was lowered to 3.5
 with diluted sulphuric acid and the emulsion was washed using
 demineralized water of 11.degree. C. At 45.degree. C. to the flocculate,
 having a volume of 1350 ml gelatin was added in order to have a gesi
 (ratio in grams of gelatin to silver) of 0.34 and demineralized water was
 added in order to have a total weight of 1923 grams. Values of pH and UAg
 at 40.degree. C. were adjusted to 5.5 and +100 mV.
 Sensitization
 The dispersed emulsion was optimally sulphur, selenium and gold sensitized
 in the presence of sodium thiocyanate and
 anhydro-5,5'-dichloro-3,3'-bis(n.sulfobutyl)-9-ethyloxacarbocyanine
 hydroxide.
 Stabilization and Preparation of the Emulsion Coating Solutions
 The light-sensitive tabular grain emulsion was stabilized with
 4-hydroxy-6-methyl-1,3,3a,7-tetra-azaindene and after addition of the
 normal coating additives the coating emulsion was coated simultaneously
 together with a protective antistress layer and an outermost afterlayer
 the compositions of which are given hereinafter:
 The protective antistress layer was coated with the following compounds,
 expressed in grams per square meter per side:

gelatin 1.10
 polymethylmethacrylate 0.023
 (average particle diameter: 6 .mu.m)
 1-p-carboxyphenyl-4,4'-dimethyl-3-pyrazolidine-1-one 0.054
 C.sub.17 H.sub.15 --CO--NH--(CH.sub.2 --CH.sub.2 --O--).sub.17 --H
 0.0188
 formaldehyde 0.1
 The composition of said outermost afterlayer was as follows:
 an ammoniumperfluorocarbonate compound represented by formula (IV)
EQU F.sub.15 C.sub.7 COONH.sub.4 (IV)
 a polyoxyethylene compound represented by the formula (V)
EQU R--O--(CH.sub.2 CH.sub.2 O).sub.n --H (V)
 with n=10 and R=oleyl and
 a polymeric thickener represented by the formula (VI)
 ##STR4##
 with a molar ratio of 3:18:79 for the distinct parts of the copolymer in
 the copolymeric latex. The three products were added to an aqueous
 solution containing up to 10% of ethyl alcohol with respect to the
 finished solution, ready for coating. Said three products were present in
 an amount of 0.75 g/l, 5.0 g/l and 6.5 g/l respectively and coated in an
 amount of 6.0 mg/m.sup.2, 40.0 mg/m.sup.2 and 52.0 mg/m.sup.2
 respectively. The amount of ethyl alcohol was evaporated during coating
 and drying. The resulting coated radiographic materials were the Matls.
 Nos. 1-3 in Table 2, coated on the respective subbed supports, coated with
 coatings A, B and C, respectively called Materials A,B and C hereinbefore.
 Evaluation of the Material Samples Nos. 1-3
 The resistance of the best conducting layer, the so-called "Q-mobile"
 value, was determined at 30% of relative humdidity ("R.H.") at room
 temperature (21.degree. C.), said value being practically independent upon
 relative humidity, and was expressed in Ohm/square. Following test
 procedure, described in Research Disclosure--June 1992, item 33840, was
 therefore applied in order to capacitively measure the resistance of the
 best conducting layer (layer having the lowest resistance) in a layer
 arrangement of a multilayered material: the resistance of the layer
 assemblage was measured contactless by arranging it between capacitor
 plates making part of a RC-circuit differentiator network. The dimensions
 of the measurement cell are chosen in such a way that relying on the known
 capacitor value (C) it is possible to calculate from the measured RC-value
 the electrical resistance of the layer assemblage. Such proceeds by
 connecting the equivalent serial circuit CR to a sine wave generator with
 output voltage U.sub.0 and angular frequency .omega.. The voltage U over
 the resistor,when plotted versus .omega., giving a cut-off frequency
 .omega..sub.0 of the high-pass frequency filter of the first order (as the
 RC-circuit is considered to be) is reached at equal capacitance and
 resistivity so that R=1/ ((.omega..sub.0.times.C). When this condition has
 been fulfilled output voltage or source voltage U.sub.0 is related to the
 voltage U.sub.R over the resistance taking into account a phase shift of
 45.degree. between the voltages so that U.sub.R =U.sub.0 xsin 45.degree..
 If the sine wave generator frequency is adjusted at the value where
 U.sub.R =U.sub.0.times.sin 45.degree. is met, wherein the amplitude or the
 phase shift or both can be measured, it is possible to determine the
 resistance by converting the formula R=1/(.omega..sub.0.times.C) into
 R=1/(2.times..pi..times.f.sub.0.times.C).
 In case of a constant coupling capacitance C there is a fixed relation
 between the resistance and the measurable time constant .tau. wherein
 .tau.=R.times.C and thus also between said time constant .tau. and the
 cut-off frequency f.sub.0. Starting from the formula RC=1/2.pi.f and from
 the limitation of the sample frequency upon the used apparatus two
 differing experimental measuring arrangements are used in order to
 determine the "Q-mobile" value over two differing regions:
 "Q.sub.MOB1 " measured over the region between 2.times.10.sup.7 and
 3.times.10.sup.13 .OMEGA./sq.; and
 "Q.sub.MOB2 " measured over the region between 3.times.10.sup.3 and
 3.times.10.sup.9 .OMEGA./sq.
 The presence or absence of sparks in form of lines on the processed film
 appearing as a consequence of "line-discharges" was examined by following
 simulation procedure. The phenomenon of spark generation detected after
 processing in a processing machine occurs when an electrostatically loaded
 operator takes an exposed, unprocessed film material from a cassette,
 wherein it was in contact with intensifying screens comprising luminescent
 phosphors, whereafter an electrical discharge appears at the moment at
 which contact is made between the film material and the inlet of the said
 processing machine. Starting from the assumption that the operator was
 loaded electrostatically following electrical scheme (FIG. 1) is
 representative for the electrical discharge phenomena: an isolated and
 loaded operator is represented by a loaded capacitor plate having a
 capacity of 100 pF up to 300 pF (with an ability to load up to a voltage
 of some ten thousands of Volts). Contact was made between a plate A (see
 FIG. 1) of a capacitor (loaded up to a capacity of 300 pF) and a film
 material sample F without making contact with any other subject (by
 hanging up the film material sample F in an isolating frame FR). The other
 capacitor plate B, without making contact with the earth, was loaded up to
 -2 kV (corresponding with a discharge energy of about 2.4 mJoule). After
 having no charging current anymore contact with the source of high voltage
 was broken. In the capacitor, between plates A and B a dielectric medium
 DM was present.
 The approach of the metal inlet of the "M6" processing machine, trademark
 product from the Eastman Kodak Co., USA, by a film material sample was
 simulated by a quick move to the film material sample F of a metal bar M
 having a relatively sharp edge (representing the inlet of the earthed
 processing machine) followed by making contact with the film to be
 processed. Time between loading said film material sample and contacting
 it with the metal bar was set to 10 seconds. This procedure was repeated
 four times for the same film material sample before processing it in the
 M6-processing machine (trademarked product from Eastman Kodak, USA),
 wherein as developer and fixer solutions G138.RTM. and G334.RTM., both
 trademarked products from Agfa-Gevaert N.V., were used respectively in a
 total processing cycle of 90 seconds. Moreover the sensitivity to
 "spark-generation" for light-sensitive materials in case of
 tribo-electrical rubbing contact was determined by means of an apparatus
 (so-called "VONKOMAT" apparatus, wherein the material to be examined was
 brought into rubbing contact with a constant contacting force and with a
 constant velocity with two reference materials tribo-electrically far
 different from each other, like polyvinyl chloride (PVC) and polymethyl
 methacrylate (PMMA). By means of a so-called spark electrode the generated
 charge became discharged in a controlled way and the thus generated spark
 pattern was examined after processing. The presence of sparks, wherein the
 surface pattern was more important than the density thereof, was
 indicative for the "spark characterization" or "spark properties" of the
 material which was determined to a great extent by following factors,
 being chargeability, conductivity and sensitivity. Expressed in figures:
 "0" is indicative for the absence of spark generation, whereas a value of
 "3", "4" or "5" is indicative for an increasing sensitivity with respect
 to spark generation. The results are summarized in Table 2 hereinafter.
 TABLE 2
 "Q-mobile" resistance of the antistatic layer showing the
 best conductivity (lowest resistance); control of "appearance of
 sparks" and "spark characterization" in "VONKOMAT" versus
 PVC and PMMA for X-ray photographic Film Materials Nos. 1-3.
 Q-mobile
 Ohm/square VONKOMAT VONKOMAT
 Matl. No. 30% R.H. vs .multidot. PVC vs .multidot. PMMA Sparks
 1 (comp.) 2.10 .times. 10.sup.6 0 0 YES
 2 (inv.) 1.30 .times. 10.sup.10 0 0 NO
 3 (comp.) 9.30 .times. 10.sup.11 3.5 0 NO
 The results as presented in the Table 2 are illustrative for the superior
 antistatic properties of the Material No. 2 according to the present
 invention with a layer composition having the desired resistance in the
 antistatic layer having the best conductivity (lowest resistance).