1. FIELD OF THE INVENTION.
[0001] The invention is related to a processing method of a light-sensitive silver halide
photographic material having satisfactory surface characteristics after rapid processing
in hardener free processing solutions.
2. BACKGROUND OF THE INVENTION
[0002] Rapid processing becomes more and more important and therefore the thickness of the
light-sensitive hydrophilic colloid layers of a photographic film is reduced. However
this causes disadvantages related with pressure sensitivity in the dry state before
or in the wet state during processing. 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 and drying
velocity. This is obviously contradictory to the trend to develop rapid processing
systems with films having thin coating layers.
[0003] Besides a demand for rapid processing there is a constant demand for processing solutions
having a simplified composition, which is friendly to customer and environment.
[0004] Mixing of different developer and/or fixing solutions is no longer necessary due
to the absence of hardening agents therein and as a consequence mistakes are avoided.
Moreover fixing solutions free from aluminum ions as a source of hardening agent provide
the possibility to enhance the pH value and to reduce the unagreable odour thereof.
[0005] It has been established however that especially 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, especially when use has been made of (rapid)
infrared drying means.
[0006] If in fixer solutions ready-for-use the amounts of hardening aluminum ions expressed
as amount of aluminum sulphate are reduced to less than 4 g per litre the first symptoms
of insufficient surface glare and unevenness phenomena occur.
3. OBJECTS OF THE INVENTION.
[0007] Therefore it is a first object of this invention to provide a photographic material
having satisfactory surface characteristics, particularly an even surface glare over
the whole film surface after rapid processing with minimum amounts of processing agents.
[0008] It is a particular object to get desired surface glare and surface glare evenness
for medical X-ray film materials having thin hydrophilic layers when processed in
less than 90, and more preferred in less than 50 seconds.
[0009] It is a further object to get the said glare evenness after a fixation step in a
processing cycle wherein a fixer is used with amounts of aluminum ions per litre of
less than 4 g expressed as equivalent amount of aluminum sulphate, and more preferably
without aluminum ions. Moreover it is an object to get less generation of inconvenient
odour from sulphur dioxide in the fixation step, said step being followed by rinsing
and rapid drying.
[0010] Other objects will become apparent from the description hereinafter.
4. SUMMARY OF THE INVENTION.
[0011] It has been found that the objects of the present invention can be attained by a
method 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
litre of aluminum ions expressed as an equivalent amount of aluminum sulphate, rinsing
and drying; characterised 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 from 0.5 to 1.5 (more preferably from 0.9 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 demineralised water of 25 °C is not more than 300 % (and more preferably
not more than 200 %).
[0012] According to the present invention it has been made possible to select an amount
of latex so that differences in average surface glare values measured as described
in ASTME D523 at a reflection angle of 60° between a processed material treated during
fixation with a fixer solution containing more than 4 g, in particular 5.44 g, per
litre of aluminum sulphate and same material treated during fixation in a fixer solution
free from aluminum ions, is less than 2%.
5. DETAILED DESCRIPTION
[0013] Preferred polymer latices used in the protective antistress layer of the light-sensitive
silver halide material used in the processing method according to the present invention
are cross-linked polymers and are prepared as described e.g. in US-A 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 US-A 5,472,832.
[0014] In the method of the present invention a 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 butylmethacrylate and acrylamide-N-isobutylsulphonic acid
sodium salt as represented in the formula (I).
[0015] Another preferred latex is polyethylacrylate, being a non-ionic polymer. A 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 µm. The polyurethane is added
to the coating solution as an aqueous latex dispersion.
[0016] An especially useful polyurethane is the one having a high procentual amount of urethane
groups, in order to get a high degree of cross-linking and as a consequence low tendency
to sticking. Moreover the presence of a lubricant in an outermost afterlayer on top
of the protective antistress layer comprising said polyurethane dispersion may be
favorable.
[0017] Said polyurethane latex can moreover be loaded with e.g. a developing agent by addition
of the aqueous loadable polyurethane latex to a solution of useful agent(s) as e.g.
a developing agent in a water-miscible organic solvent as e.g. acetone, or by simultaneous
addition of said latex and said solution to an aqueous gelatinous solution as gelatin
is a preferred binder for this loaded latex. A mixture of developing agents including
a dihydroxybenzene like hydroquinone and a 3-pyrazolidine-1-one developing agent as
e.g. 1-phenyl-3-pyrazolidine-1-one also known as "phenidone", being an electron transfer
agent or super additive developer, can be used in combination, in that case preferably
in a respective molar ratio of from 2/1 to 10/1. In that case dihydroxybenzene or
dihydroxybenzenes is (are) preferably present in an amount of from 0.05 to 0.5 g for
a coverage of silver halide equivalent with 1 g of silver nitrate. Ascorbic acid,
iso-ascorbic acid whether or not in combination with the preferred developing agent(s)
can also be used. In this way a so-called "activation material" can be obtained which
can be developed by means of an alkaline solution.
[0018] In accordance with the method of the present invention the latex should be present
in the gelatinous protective layer(s) of the material to be processed in an amount
in order to reduce the relative deviation of glare measured by reflection measurements
as described in ASTME-D523 at a reflection angle of 60° to a value of not more than
2 %. Therefore measurements of glare are performed by means of a reflectometer under
an angle of 60° at 10 different sites at the processed film surface in two different
developing conditions: one in the presence in the fixer solution of at least 4 g of
aluminum expressed as an equivalent amount of aluminum sulphate in the processing
solutions and one in the absence thereof as will become clear from the Examples. The
commercially available G334 fixer, trademarked product from Agfa-Gevaert NV, used
in the tests, contains 5.44 g of aluminum sulphate in a fixer solution ready-for-use.
In principle developer solutions may contain a hardening agent, but in a preferred
embodiment said solutions are also free from hardening agents.
[0019] In praxis said latex polymer(s) coated in the gelatinous protective antistress layer
is (are) present in an amount of at least 50 % by weight versus the total amount of
gelatin present therein as a binder, and even more preferably in an amount of at least
90%. The maximum ratio by weight of latex polymer(s) to gelatin binder is preferably
1.5.
[0020] In addition the said latex-type (co)polymers may optionally be present in a gelatin
free afterlayer (if present) applied over the protective antistress layer and even
in one or more emulsion layer(s) coated between said protective antistress layer and
a subbed support, the subbing layer of which may be overcoated with at least one gelatinous
intermediate layer.
[0021] As has been set forth the swelling degree of said photographic material to be processed
according to the method of this invention after immersing said material for 3 minutes
in demineralised water of 25 °C shouldn't exceed 300 % and even more preferred shouldn't
exceed 200 %. Said swelling degree expresses the requirement to sufficiently harden
the binder in the light-sensitive silver halide photographic material used in processing
method of this invention.
[0022] In order to express the hardening in a quantitative manner as a procentual swelling
degree the following method is applied. After incubating a sample of a light-sensitive
silver halide photographic material at 57 °C and 34 % RH for 3 days the thickness
(a) of the layer assemblage is measured. Thereafter the sample is immersed in distilled
water at 21°C for 3 minutes and the thickness (b) of the swollen layer is measured
by means of the technique described in US-A 4,414,304.
[0023] The swelling ratio is then calculated as:
[0024] Layers and layer arrangements which can be applied to the film material in the processing
method according to the present invention are those described in EP-A 0 752 617, in
EP-A's 0 712 036 and 0 712 034, in EP-A's 0 677 773 and 0 678 772, in EP-A's 0 610
608; 0 610 609 and in EP-A 0 569 075, in US-A's 4,092,168 and 4,311,787; in DE 2,453,217
and in GB Patent 7,907,440.
[0025] The gelatin coverage in the protective layer is preferably not higher than about
1.50 g per m
2 and is more preferably in the range from 0.60 to 1.50 g per m
2.
[0026] In the antistress layer(s) comprising a polyurethane latex and/or the latex-type
polymers or copolymers described hereinbefore, hydrophilic colloid binders differing
from gelatin that can be homogeneously mixed therewith are e.g. other proteinaceous
colloids, polysaccharides as e.g. starch and polydextranes, as well as synthetic substitutes
for gelatin as e.g. poly-N-vinylpyrrolidone, polyvinyl alcohol, polyacrylamide, polyacrylic
acid, polymethylacrylate, polyethyl-acrylate, polymethyl-methacrylate, polyethylmethacrylate,
polyvinyl imidazole, polyvinyl pyrazole and derivatives thereof as well as styrene-maleïc
acid or a styrene-maleïc acid anhydrid type copolymer.
[0027] Furthermore the use of mixtures of said hydrophilic colloids is not excluded. Among
these binders as already set forth hereinbefore the most preferred one 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, N° 16, page 30 (1966). In order to minimise the amount of gelatin, said gelatin
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, 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 polymerisable monomers on gelatin, and cellulose derivatives
such as hydroxyalkyl cellulose, carboxymethyl cellulose, phthaloyl cellulose, and
cellulose sulphates.
[0028] In a preferred embodiment gelatin in the antistress layer is partially replaced by
colloidal silica as it gives rise to a further improvement of the obtained properties
of the material processed according to the method of this invention. Preferably colloidal
silica having an average particle size of not larger than 10 nm and with a surface
area of at least 300 m
2 per gram is used. Especially preferred colloidal silica particles have a surface
area of 500 m2 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). Colloidal silica is preferably present at a coverage
of at least 50 mg per m
2. Further the coverage of said colloidal silica in the antistress layer is preferably
in the range of 50 mg to 500 mg per m
2.
[0029] 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.
[0030] The gelatin binder can be forehardened with appropriate hardening agents such as
those of the epoxide type, those of the ethylene-imine type, those of the vinylsulfone
type as e.g. 1,3-vinylsulphonyl-2-propanol, bis-vinyl-sulphonyl methyl or bis-vinyl
sulphonyl ethyl ether, hydroxy substituted vinyl sulphonyl hardeners, chromium salts
as e.g. chromium acetate and chromium alum, aldehydes as e.g. formaldehyde, glyoxal,
and glutaraldehyde, N-methylol compounds as e.g. dimethylolurea and methyloldimethylhydantoin,
dioxan derivatives as e.g. 2,3-dihydroxy-dioxan, active vinyl compounds as e.g. 1,3,5-triacryloyl-hexahydro-s-triazine,
active halogen compounds as e.g. 2,4-dichloro-6-hydroxy-s-triazine, and mucohalogenic
acids as 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 US-A 4,063,952 and with the onium
compounds as disclosed in EP-A 0 408 143.
[0031] To the ionic or non-ionic latex polymers or latex copolymeric combinations of monomers
cited hereinbefore can optionally be added in addition non-ionic surfactant(s) having
antistatic characteristics such as e.g. polyoxyethylene compounds. In a more preferred
embodiment the said surfactant(s) is (are) present in an optionally present outermost
layer at the side of the support where the emulsion layer(s) has (have) been coated.
Said layer may be a gelatin free afterlayer or a thin gelatinous layer.
In a preferred embodiment a latex polymer having antistatic properties is added to
the protective antistress layer containing the latex polymer(s) set forth hereinbefore.
A preferred one is the latex of a cross-linked polymer, being a copolymer of an acrylic
and/or methacrylic acid ester including 90-99 mole % of acrylate and/or methacrylate
units and 1 to 10 mole % of tetraallyloxyethane units as polyfunctional crosslinking
monomer, wherein in said copolymer at least 75 % of the ester groups have been transformed
into alkali metal carboxylate groups, thus exhibiting ionic characteristics: especially
preferred as a cross-linked ionic polymer is poly([c.l.]tetraallyloxyethane-co-methyl
acrylate/acrylic acid), the formula (II) of which is given hereinafter with a preferable
3/18/79 molar ratio set forth in EP-A 0 644 456
[0032] Other antistatic agents can be provided therein as has e.g. been given in US-P 5,391,472.
A gelatin-free antistatic afterlayer, if present, 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 generally have
an average particle size which is comprised between 0.2 and 10 µm. 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 US-A 4,614,708.
[0033] The coating of the layers of the material used in the processing method according
to the present invention 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
US-A 4,218,533, may be applied if an afterlayer is present.
[0034] In order to regulate the viscosity of the coating solutions 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, synthetic (smectite) clays 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 are e.g. US-A 3,167,410, Belgian
Patent No. 558.143, JP-A's 53/18687 and 58/36768 and DE 3 836 945.
[0035] In addition to the binder(s), silver halide(s) and, optionally, developing agent(s)
the silver halide photographic material may contain in the light-sensitive emulsion
layer(s) and/or in one or more layers in water-permeable relationship with said silver
halide emulsion layer(s) any of the kinds of compounds customarily used in such layers
for improving the photographic process, manufacture or preservability (storage). For
example such layers may incorporate one or more coating aids, stabilising agents or
antifogging agents as described e.g. in GB-P 1,007,020 filed March 6, 1963 by Agfa
A.G., plasticizers, development-modifying agents e.g. polyoxyalkylene compounds, onium
compounds, and sulphur compounds of the class which have sulphur covalently bound
derived from an ion such as a mercaptide or xanthate or coordinately bound sulphur
from a thioether. Preferably thioethers acting as silver chelating agents with at
least two sulphur atoms as donors are used. A survey of thioether compounds suitable
for incorporation in silver halide emulsion layers of widely varying silver halide
composition has been given in the EP-A 0 026 520. Useful compounds have further been
described in EP-A's 0 634 688 and 0 674 215.
[0036] Silver halide emulsion crystals used in the silver halide emulsion layer(s) of the
material processed according to the method of the present invention are composed of
silver chloride, silver chlorobromide, silver chloroiodide, silver chlorobromoiodide,
silver bromide or silver bromoiodide. Regular as well as tabular crystals may be present,
as well as mixtures thereof. Crystals having a different crystal habit may be coated
in different layers as e.g. in EP-Application No. 95202897, filed October 25, 1995.
[0037] Amounts of iodide of not more than 2 mole % are preferred in the said crystals and
even more preferred is an iodide content of from 0.1 to 1 mole %. Silver halide crystals
having a regular crystal habit preferably have an average grain size of at least 0.15
µm, up to at most 1.2 µm, more preferably up to 1.0 µm and still more preferably up
to 0.8 µm. Silver halide crystals having tabular {111} major faces accounting for
at least 50 % of the total projected area preferably have an average diameter from
0.5 to 2.5 µm and an average thickness from 0.06 to at most 0.3 µm, and even more
preferred to at most 0.2 µm. Average aspect ratios of from 2 to 20 and more preferred
from 5 to 15 are preferred. Said silver halide crystals may have been prepared in
gelatin and/or in colloidal silica as a protective colloid. Preparations in colloidal
silica have e.g. been described in EP-A 0 754 964; in EP-A's 0 677 773; 0 682 287
and 0 649 051.
[0038] Supports and subbing layers coated adjacent thereto, useful for the film materials
in the system according to this invention, can be those as described in Chapter XV
of RD 36544 and RD 38957 (published September 1994 and September 1996 respectively),
polyethylene naphthalate inclusive.
[0039] The hydrophobic resin support may be provided with one or more subbing layers known
to those skilled in the art for adhering thereto a hydrophilic colloid layer. Suitable
subbing layers for polyethylene terephthalate supports are described e.g. in US-A
3,397,988, 3,649,336, 4,123,278 and 4,478,907. For high speed processing applications
a useful subbing layer is disclosed e.g. in JP-A 01 166 031. Vinylidene chloride and
styrene-butadiene copolymers are the most well-known polymers for practical use as
subbing layer ingredients in the material to be processed according to the method
of this invention.
[0040] Photographic silver halide emulsion materials, suitable for use in the processing
method of the present invention are materials for continuous tone or halftone photography,
microphotography and radiography, in black-and-white as well as colour photographic
materials. Said materials are thus selected from the group consisting of materials
having one or more light-sensitive silver halide emulsion layers at one or at both
sides of the support. Preferred materials are X-ray materials, single-side as well
as double side coated, and more preferred medical X-ray materials.
[0041] Said materials may be imagewise exposed by means of any radiation source, depending
on their application as has been described e.g. in RD's 36544 and 38957, chapter XVI.
[0042] Ecological advantages of the processing method of said imagewise exposed materials
according to the method of the present invention are related with the use of fixer
solutions ready-for-use containing less than 4 g of aluminum per liter expressed as
an equivalent amount of aluminum sulphate and, more preferably, without aluminum ions.
In a preferred embodiment also the developer is free from the generally used well-known
glutardialdehyde hardener. A time saving factor is the total processing time: rapid
processing proceeds within a time of less than 90 seconds, more preferred within a
time of less than 50 seconds e.g. within a time from 20 to 45 seconds, in automatic
processing machines as e.g. CURIX HT 530, trade marketed product from Agfa-Gevaert
N.V..
[0043] For ecological reasons fixers having high sodium thiosulphate concentrations are
preferred over fixers containing ammonium thiosulphate. They are useful in those circumstances
wherein no replenishment system is available or where it is desirable to minimise
the replenishment amounts. Such fixers retain a high silver binding capacity and a
sufficient fixing speed even after prolonged continuous processing without replenishment
or with minimum replenishment. An example thereof has been given in Research Disclosure
355 039, p. 736-737, published November 1, 1993.
[0044] In order to reduce or to minimise odour by formation of sulphur dioxide fixation
proceeds in a fixer at a pH value of at least 4.6 and even more preferred in a fixer
having a pH value of at least 5.0, a condition which can be the better fulfilled the
lower the concentration of aluminum ions is as precipitation of aluminum hydroxyde
should be avoided. In the most preferred embodiment no aluminum is present at all
as has already been established hereinbefore. Nevertheless the processing method of
the present invention remains very useful in order to get the desired surface glare
without unevenness when aluminum ions are present in an amount of from 0.1 up to less
than 4 g, expressed as an equivalent amount of aluminum sulphate, per liter of fixer.
[0045] After fixing and rinsing, drying preferably proceeds by means of infrared drying
means as has e.g. been described in EP-A 0 620 482 for non-destructive testing film
materials. In these drying circumstances the improvement of surface characteristics
is in the best mode, especially thanks to the composition of the antistress layer.
[0046] As a result of the present invention after processing a forehardened light-sensitive
silver halide photographic material in hardener free fixing and, optionally, developing
solutions said processed material shows the desired surface glare and moreover no
unevenness of said surface glare over the processed film surface. Even for thin coated
layers of the materials for use in the rapid processing method according to the present
invention the same advantages can be recognised. Furthermore the appearance of sludge
in the processing is significantly reduced.
[0047] The present invention is illustrated by the following examples without however being
limited thereto.
EXAMPLES
EXAMPLE 1
General preparation of the photographic material.
[0048] A photographic material was prepared composed of
- a subbed polyester base (175 µm thick);
- an emulsion layer comprising a gelatin-silver halide emulsion (preparation described
hereinafter) of which the silver halide consists for 99 mole % of silver bromide and
1 mole % of silver iodide having a tabular {111} crystal habit;
- a protective antistress layer having the composition given hereinafter.
Preparation of the tabular silver bromoiodide emulsion.
Nucleation step:
[0049] 41.3 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 2.16 liter
of destilled water at 45°C, 12.6 grams of potassium bromide and 12.5 grams of gelatin.
After one minute the reaction temperature of this mixture was raised to 70°C in 20
minutes and 47.5 grams of phthalated gelatin in 475 ml destilled water were added.
After 10 minutes the neutralisation step was started.
First neutralisation step:
[0050] 21.7 ml of solution 1 were added to the reaction vessel at a rate of 7.5 ml per minute
to reach a pBr value of 1.63, whereafter the first growth step was started.
First growth step:
[0051] A double jet precipitation was started using solutions 1 and 2 which continued for
40 minutes 51 seconds. During this precipitation, the pBr value was kept constant
at 1.63. The flowing rate of solution 1 was 7.5 ml per minute at the start, linearly
increasing to 26.7 ml per minute at the end of the precipitation. Thereafter the second
neutralisation phase was started.
Second neutralisation step:
[0052] 45.8 ml of solution 1 was added at a rate of 7.5 ml per minute so that a pBr of 2.77
was obtained. The precipitation was then continued by a second growth step.
Second growth step (during which 47.0 % of the total amount of AgNO3 was used):
[0053] 704 ml of solution 1 was injected in the reaction vessel at a rate of 7.5 ml per
minute at the start linearly increasing to 37.5 ml per minute at the end of the precipitation.
The pBr was kept constant at 2.77 using solution 2 for the first 8 minutes and 51
seconds, followed by the replacement of solution 2 by solution 3 for the rest of the
precipitation.
The tabular grain emulsion, corresponding to this invention, had the following characteristics,
measured with electron microscopic techniques:
-average diameter: 1.26 µm
-coefficient of variation of the tabular grains : 0.37
-average thickness: 0.15 µm
-aspect-ratio : 8.9
-percentage of total projective surface: 99 %.
Washing and dispersing procedure.
[0054] 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°C. At 45°C
160 grams of gelatin were added and the values of pH and pAg at 40°C were adjusted
to 5.5 and 8.15.
Sensitisation
[0055] Emulsions 1 to 4 were each optimally sulphur and gold sensitized in the presence
of sodium thiocyanate and anhydro-5,5'-dichloro-3,3'-bis(n.sulfobutyl)-9-ethyloxacarbo-cyanine
hydroxide
[0056] An X-ray photographic material was provided with on top the protective antistress
layer covering the silver halide emulsion layer. Use was made of the slide hopper
coating technique for simultaneous application of the emulsion coating and the antistress
coating.
Coating.
[0057] Each emulsion was stabilized with 4-hydroxy-6-methyl-1,3,3a,7-tetra-azaindene and
after addition of the normal coating additives the solutions were coated simultaneously
together with a protective layer containing 1.1 g gelatine per m
2 per side on both sides of a polyethylene terephthalate film support having a thickness
of 175 µm. The resulting photographic material contained per side an amount of silver
halide corresponding to 3.5 grams of AgNO
3 per m
2.
Protective Antistress.
[0058] The said protective antistress layer was coated with the following compounds, expressed
in grams per square meter per side:
gelatin |
1.10 |
polymethylmethacrylate (average particle diameter : 6 µm) |
0.023 |
1-p-carboxyphenyl-4,4'-dimethyl-3-pyrazolidine-1-one |
0.054 |
C17H15-CO-NH-(CH2-CH2-O-)17-H |
0.0188 |
formaldehyde |
0.1 |
Film A (comparative example): the gelatinous protective antistress layer had the above
conventional composition.
Film B (inventive example): the gelatinous protective antistress layer contained in
addition to the above ingredients polyurethane latex IMPRANIL in an amount of 0.6
g/m2.
Polymer latex IMPRANIL 43056 was prepared as follows: a 40 % by weight of IMPRANIL-latex
was diluted with water in order to obtain a 20 % latex, pH was adjusted with acetic
acid.
Exposure,sensitometric and densitometric data:
[0059] Samples of these coatings were exposed with green light of 540 nm during 0.1 seconds
using a continuous wedge and were processed during the 90 seconds cycle described
below. The density as a function of the light dose was measured and therefrom were
determined the following parameters:
-fog level F (with an accuracy of 0.001 density),
-the relative speed S at a density of 1 above fog (the sample with the comparative
example was adjusted to a relative speed value of 100) ,
-the contrast C, calculated between the densities 0.25 and 2.0 above fog.
[0060] The processing conditions and the composition of the processing solutions is given
hereinafter. The processing of the described photographic materials in accordance
with this invention proceeds in the processing machine CURIX HT530 (Agfa-Gevaert trademarked
name) with the following time (in seconds) and temperature (in °C) characteristics:
loading |
0.2 sec. |
|
developing |
9.3 sec. |
35°C (developer described below) |
cross-over |
1.4 sec. |
|
rinsing |
0.9 sec. |
|
cross-over |
1.5 sec. |
|
fixing |
6.6 sec. |
35°C (fixer described below) |
cross-over |
2.0 sec. |
|
rinsing |
4.4 sec. |
20°C |
cross-over |
4.6 sec. |
|
drying |
6.7 sec. |
|
total |
sec. |
|
Composition of the Developer:
[0061]
-concentrated part : |
water |
200 ml |
potassium bromide |
12 grams |
potassium sulphite (65% solution) |
249 grams |
ethylenediaminetetraacetic acid, sodium salt,trihydrate |
9.6 grams |
hydroquinone |
106 grams |
5-methylbenzotriazole |
0.076 grams |
1-phenyl-5-mercaptotetrazole |
0.040 grams |
sodiumtetraborate (decahydrate) |
70 grams |
potassium carbonate |
38 grams |
potassium hydroxide |
49 grams |
diethylene glycol |
11 grams |
potassium iodide |
0.088 grams |
4-hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidinone |
12 grams |
Water to make 1 liter |
|
pH adjusted to 11.15 at 25°C with potassium hydroxide. |
For initiation of the processing one part of the concentrated developer was mixed
with 3 parts of water.
No starter was added.
The pH of this mixture was 10.30 at 25°C.
Composition of the fixer:
[0062]
-concentrated part : |
ammonium thiosulfate (78% solution) |
661 grams |
sodium sulphite |
54 grams |
boric acid |
25 grams |
sodium acetate-trihydrate |
70 grams |
acetic acid |
40 grams |
water to make 1 liter |
|
pH adjusted with acetic acid to 5.30 at 25°C |
To make this fixer ready for use one part of this concentrated part was mixed with
4 parts of water. A pH of 5.25 was measured at 25°C.
Alternatively the same materials A and B were processed in the G138 developer and
G334 fixer solution, both solutions being trademarked products from Agfa-Gevaert NV,
containing glutardialdehyde and aluminum sulphate respectively. G138 and G334 were
applied in their normal processing cycle of 90 seconds.
Sensitometric results are summarised in Table 1.
Table 1
Film |
Fog F (x 1000) |
Speed S |
Contrast C |
A (comp.)/RPC |
14 |
98 |
317 |
B (inv.)/RPC |
14 |
98 |
302 |
A / G138/G334 |
20 |
100 |
302 |
B / G138/G334 |
22 |
99 |
297 |
RPC = rapid processing cycle |
[0063] From Table 1 it can be concluded that almost the same sensitometric results were
obtained for both materials in the rapid processing cycle without hardening agent
in both fixer and developer as in the 90 seconds processing cycle with fixer and developer
both containing hardening agents.
[0064] For the two coated film materials A and B an evaluation of differences of surface
glare characteristics after rapid processing in hardener free and normal processing
in hardener containing processing solutions was further made quantitatively.
[0065] It was not possible to derive surface glare characteristics from surface roughness
data as optical theory for light interacting with smooth and rough surfaces tells
that sinusoidal roughness differences of 0.01 µm reduce gloss by ca. 40 % as has been
set forth in Journal of Coatings Technology, Vol. 67 (851), p. 61, published December
1995.
[0066] Therefor use was made of the measurement technique with a reflectometer as described
in ASTM D523, 1985, corresponding with DIN 67530 (01.82) and ISO 2813 (1978) wherein
reflections are measured at values of the reflection angles of 20° and 60°. Measurement
normally takes place at reflection angles of 20° in the case of high gloss and at
60° for moderate gloss as decreasing values are obtained at lower measurement angles.
[0067] Measurements were made at 10 different sites at the film surface. Average values
were calculated and differences (δGlare) were further calculated between said average
values obtained in hardener free (rapid) processing and in hardener containing processing
respectively.
The corresponding results are summarised in Table 2.
Table 2
Film Coating |
δGlare (angle: 20°) |
δGlare (angle: 60°) |
A (comparative) |
6.5 |
19 |
B (invention) |
0.6 |
1.5 |
[0068] As can be concluded from Table 2 differences in surface glare are about 10 times
lower for materials having a composition for use in the method of this invention if
compared with comparative materials. For those "invention materials" differences in
surface glare are about neglectable (less than 2 %, even if measured at a surface
angle of 60°) after processing in rapid processing cycles without hardening agents
if compared with the result after processing in normal processing cycles with solutions
containing hardening agent(s).