FIELD OF THE INVENTION
[0001] The present invention relates to a silver halide photographic material, more particularly
to a silver halide photographic material having improved antistatic property and improved
coating ability.
BACKGROUND OF THE INVENTION
[0002] Silver halide photographic materials are generally composed of an electrically insulating
support and photographic layers coated thereon. Such a structure promotes the formation
and accumulation of static charges when subjecting the photographic materials to friction
or separation, caused by contact with the surface of the same or different materials
during steps for manufacturing of the photographic materials or when using them for
photographic purposes. These accumulated static charges cause several drawbacks. The
most serious drawback is discharge of accumulated charges prior to development processing,
by which the light-sensitive silver halide emulsion layer is exposed to light to form
dot, spots, or branched or feathery linear specks when development of the photographic
film is carried out. This phenomenon is called "static marks". Such static marks cause
a reduction of the commercial value of photographic films, which sometimes become
useless. For example, the formation of static marks in medical or industrial X-ray
films may result in a very dangerous judgment or erroneous diagnosis. Static marks
are a particular problem because it becomes evident for the first time after development.
Further, these static charges are also the origin of secondary problems such as adhesion
of dust to the surface of films, uneven coating, and the like.
[0003] As mentioned above, static charge is frequently accumulated when manufacturing and/or
using silver halide photographic materials. For example, during production, they are
generated by friction of the photographic film contacting a roller or by separation
of the emulsion surface from a support surface during a rolling or unrolling step.
Further, they are generated on X-ray films in an automatic apparatus by contact with
or separation from mechanical parts or fluorescent screens, or they are generated
by contact with or separation from rollers and bars made of rubber, metal, or plastics
in a bonding machine or an automatic developing machine or an automatic developing
apparatus or in a camera in the case of color negative films or color reversal films.
In addition they can be generated by contact with packing materials, and the like.
[0004] Silver halide photographic materials having high sensitivity and handling speed are
subject to an increase of static mark appearance. In particular, static marks are
easily generated because of high sensitization of the photographic material and severe
handling conditions such as high speed coating, high speed exposure, and high speed
automatic processing.
[0005] To prevent problems caused by static charges, it is suitable to add an antistatic
agent to the silver halide photographic materials. However, antistatic agents conventionally
used in other fields cannot be used universally for silver halide photographic materials,
because they are subjected to various restrictions due to the nature of the photographic
materials. More specifically, the antistatic agents which can be used in silver halide
photographic materials must have excellent antistatic abilities while not having adverse
influences upon photographic properties of the photographic materials, such as sensitivity,
fog, granularity, and sharpness. Such antistatic agents also must not have adverse
influences upon the film strength and upon antiadhesion properties. Furthermore, the
antistatic agents must not accelerate exhaustion of processing solutions and not deteriorate
adhesive strength between layers composing the silver halide photographic material.
[0006] In the art of silver halide photographic materials, a wide number of solutions to
the above described problems have been suggested in patent and literature references,
mainly based on charge control agents and electrically conductive compounds coated
on the silver halide emulsion layer together with a binder as an antistatic layer.
[0007] The most useful charge control agents known in the art are ionic and non-ionic surfactants
as well as ionic salts. Fluorinated surfactants are often mentioned as good antistatic
agents in silver halide photographic materials.
[0008] Electrically conductive compounds are mainly focused on conductive polymers such
as ionic polymers and electronically conductive polymers.
[0009] The use of ionic and non-ionic surfactants as well as fluorinated surfactants is
widely disclosed in many patents, such as, for example, US 2,600,831, 2,719,087, 2,982,651,
3,026,202, 3,428,456, 3,457,076, 3,454,625, 3,552,972, 3,655,387, 3,850,640, 3,850,642,
4,192,683, 4,267,265, 4,304,852, 4,330,618, 4,367,283, 4,474,873, 4,510,233, 4,518,354,
4,596,766, 4,649,102, 4,703,000, 4,847,186, 4,891,307, 4,891,308, 4,916,054, EP 245,090,
300,259, 319,951, 370,404, and the like.
[0010] The use of conductive polymers is widely disclosed in many other patents, such as,
for example, US 2,882,157, 2,972,535, 3,062,785, 3,262,807, 3,514,291, 3,615,531,
3,753,716, 3,769,020, 3,791,831, 3,861,924, 3,938,999, 4,147,550, 4,225,665, 4,363,872,
4,388,402, 4,460,679, 4,582,783, 4,585,730, 4,590,151, 4,701,403, 4,960,687, EP 35,614,
36,702, 87,688, 391,176, 391,402, 424,010, GB 815,662, 1,222,595, 1,539,866, 2,001,078,
2,109,705.
[0011] In particular, US 4,272,615 discloses the use of a non-ionic perfluoroalkenylpolyoxyethylene
surfactant, US 4,649,102 discloses the combination of a non-ionic surfactant and an
anionic surfactant having a polyoxyethylene group therein, US 4,847,186 discloses
the use of a fluorinated ionic or non-ionic compound, EP 245,090 discloses the combination
of fluoroalkylpolyoxyethylene compounds with fluorine-containing polymers and a polyoxyethylene
non-ionic surfactant together with a high-molecular high weight hardening agent, US
3,850,640 discloses the combination of a first layer comprising an anionic surfactant
and a second layer comprising cationic and non-ionic surfactants, US 4,596,766 discloses
the combination of a polyoxyethylene non-ionic surfactant and a fluorine-containing
compound, US 4,367,283 discloses the combination of a polyoxyethylene non-ionic surfactant,
a sulfonated surfactant, and a fluorine-containing phosphate surfactant, US 4,335,201
discloses the use anionic fluoroalkyl surfactant, such as fluoroalkyl sulfonate, sulfate
and carboxylate salts, GB 2,246,870 discloses the combination of a polyoxyalkylene
compound and a polystyrenesulfonate compound, US 5,037,871 and WO 91/18325 disclose
the use of hydrolyzed metal lower alkoxide in combination with fluoroalkyl polyether
surfactants and a water-soluble hydroxylated polymer, US 4,891,308 discloses the use
of ionic and non-ionic fluorine containing surfactant together with a fluorine free
non-ionic surfactant, EP 319,951 describes the combination of an anionic and non-ionic
surfactant with a fluorinated non-ionic surfactant, US 4,610,955 and 4,582,781 describe
the combination of an inorganic salt with polymers containing blocks of polymerized
oxyalkylene monomers, US 5,176,943 discloses an antistatic composition comprising
an ionic perfluoro surfactant, a nonionic perfluoro surfactant and a nonfluorinated,
copolymerizable, radiation curable prepolymer, US 5,258,276 discloses a ternary surfactant
system comprising a mixture of a specific anionic and two specific nonionic surfactants.
[0012] However, many of these substances and combinations thereof exhibit great specificity,
depending upon the kind of film support or the photographic composition. Although
some substances produce good results on certain specific film supports, photographic
emulsions or other photographic elements, they are not only useless for preventing
generation of static marks when using different film supports and photographic elements,
but also may have an adverse influence upon photographic properties.
[0013] On the other hand, there are many cases wherein, although they have excellent antistatic
effects, they cannot be used due to their adverse influence upon photographic properties
such as sensitivity, fog, granularity, sharpness, and the like.
[0014] For example, it has been well known that polyethylene oxide compounds have antistatic
effects, but they often have an adverse influence upon photographic properties, such
as an increase in fog, desensitization, and deterioration of granularity, in particular
in silver halide photographic materials in which both sides of the support are coated
with silver halide emulsions, such as medical X-ray photographic materials. The combination
of polyoxyethylene compounds with organic salts can improve the surface resistivity,
but also may increase of tackiness and film-to-film adhesion.
[0015] The use of fluorinated surfactants for controlling the electricity generation caused
by friction or contacting with different materials, such as, for example, rollers,
increases the charging in negative polarity. Accordingly, although it is possible
to adapt the electric characteristics of the silver halide photographic material for
each roller, such as, for example, rubber rollers, Delrin™ rollers, and nylon rollers
by suitably combining the fluorinated surfactants with surfactants, charging in positive
polarity problems still occurs, because a general solution for all kind of rollers
cannot be obtained.
[0016] Moreover, the market requirement of silver halide photographic material having a
reduced processing time has increased the problems of static charges due to the higher
speed to which silver halide photographic materials go through the automatic processors.
[0017] Furthermore, the increasing demand of the radiographic market of medical X-ray silver
halide photographic material, due to the increase in the worldwide consumption and
diffusion of apparatus for X-ray diagnosis, requires an increase in productivity of
medical X-ray photographic material that can be obtained with an increase of coating
speed. Higher coating speed increases the likelyhood of static charges if conventional
antistatic agents are used.
SUMMARY OF THE INVENTION
[0018] The present invention relates to a silver halide photographic material comprising
a support, at least one silver halide emulsion layer coated thereon, and a hydrophilic
colloid layer coated on said at least one silver halide emulsion layer, wherein said
hydrophilic colloid layer comprises a combination of (a) at least one surfactant selected
from the group consisting of non-ionic perfluoroalkyl(ene)polyoxyethylene surfactants
and polyoxyethylene-modified polysiloxane surfactants, and (b) at least one salt selected
from the group of salts of perfluoroalkylsulfonyl imide or perfluoroalkylsulfonyl
methide.
DETAILED DESCRIPTION OF THE INVENTION
[0019] The silver halide photographic material according to the present invention comprises
a combination of a non-ionic perfluoroalkyl(ene)polyoxy-ethylene surfactant and/or
a polyoxyethylene-modified polysiloxane surfactant, and at least one salt of a perfluoroalkylsulfonyl
imide or perfluoroalkylsulfonyl methide. The combination is coated on the silver halide
emulsion layer together with a hydrophilic binder as a top-coat protective layer.
[0020] The term "non-ionic perfluoroalkyl(ene)polyoxyethylene surfactants" means a non-ionic
surfactant comprising a mixture of compounds consisting in an alkyl or alkylene group
of from 4 to 16 carbon atoms wherein the hydrogens are totally replaced by fluorine
atoms (at least 90% of the hydrogens are replaced by fluorine) joined to a polyoxyethylene
group comprising from 6 to 30 oxyethylene groups.
[0021] According to the scope of the present invention when the term "group" is used to
describe a chemical compound or substituent, the described chemical material includes
the basic group and that group with conventional substitution. Where the term "moiety"
is used to describe a chemical compound or substituent only an unsubstituted chemical
material is intended to be included.
[0022] The non-ionic perfluoroalkyl(ene)polyoxyethylene surfactants can be represented by
the following formula:

wherein Rf can be a perfluoroalkyl group, a perfluoroalkylene group, a perfluorocycloalkyl
group, and a perfluorocycloalkylene group having from 4 to 16 carbon atoms, X can
be -O-, -SO₂NR''-, -CONR'', -CH₂O-, or a single bond, R, R' and R'' are, independently,
hydrogen or a lower alkyl of from 1 to 4 carbon atoms, and y is a number from 6 to
30.
[0023] A particularly preferred non-ionic perfluoroalkylpolyoxyethylene surfactant is the
Zonyl™ FSN, a trade name of DuPont Company. Non-ionic perfluoroalkyl(ene)polyoxyethylene
surfactants are used in amount of from 10 to 100 mg/m², preferably from 20 to 60 mg/m²,
more preferably of about 40 mg/m² of top-coat protective layer. Other useful non-ionic
perfluoroalkyl(ene)poly-oxyethylene surfactants are listed below.

The polyoxyethylene-modified polysiloxane surfactant comprises a non-ionic polysiloxane
polymer (preferably having a linear polymeric backbone) which has pendant polyoxyethylene
polymeric units adhered to the polysiloxane backbone. The polyoxyethylene chain is
preferably linked to the polysiloxane through ether linkages, and the polyoxyethylene
may also contain propylene units as random or block units throughout the polyoxyethylene
chain. The polyoxyethylene-modified polysiloxane surfactant can be better represented
by the following formula:

wherein R is a lower alkyl having from 1 to 4 carbon atoms, R' is a lower alkylene
having from 1 to 4 carbon atoms, R'' is hydrogen or a lower alkyl of from 1 to 4 carbon
atoms, m is an integer from 5 to 100, n is an integer from 2 to 50, p is an integer
from 5 to 50, and q is an integer from 0 to 50. Compounds of this class are sold by
Union Carbide Co., under the trade name of Silwet™. Examples of useful compounds for
use in the combination of the present invention are Silwet™ L-7605, Silwet™ L-77,
Silwet™ L-7001, and the like. The polyoxyethylene-modified polysiloxane surfactants
are used in amount of from 1 to 100 mg/m², preferably from 5 to 50 mg/m² of top-coat
protective layer.
[0024] The salt of perfluoroalkylsulfonyl imide or perfluoroalkylsulfonyl methide useful
in the combination of the present invention can be represented by the following formula:

wherein Rf is a fluorinated alkyl group having 1 to 10 carbon atoms, X is nitrogen
or carbon atom, M is an organic or inorganic cation, and v is the X valence, and wherein
two Rf groups can join together to form a ring.
[0025] In a preferred embodiment M can be any of alkali metal cations, alkaline-earth metal
cations, an alkyl ammonium cation, or a quaternary ammonium cation. In a more preferred
embodiment M can be Li⁺, Na⁺, K⁺. In the most preferred embodiment M is Li⁺.
[0026] In a preferred embodiment, v is 3 when X is nitrogen atom, and v is 4 when X is a
carbon atom.
[0027] A description of the above mentioned compounds and their synthesis can be found in
US 4,505,997, US 5,021,308, US 5,072,040, US 5,162,177 and 5,273,840, incorporated
herein by reference. Examples of lithium salts of perfluoroalkylsulfonyl imide or
perfluoroalkylsulfonyl methide are illustrated below. However, the present invention
is not limited to the following examples.

The salts of perfluoroalkylsulfonyl imides or perfluoroalkylsulfonyl methides are
employed in an amount of from 1 to 100 mg/m², preferably from 5 to 80 mg/m², more
preferably from 10 to 70 mg/m² of top-coat protective layer.
[0028] The top-coat layer comprising the antistatic combination of the present invention
can comprise other compounds conventionally known in the art, such as, for example,
coating aids, hardeners, and the like. Particularly useful coating aids are ionic
and non-ionic polyoxyethylene surfactants and alkylsulfate surfactants. The antistatic
layer of the present invention may contain other addenda which do not influence the
antistatic properties of the layer, such as, for example, matting agents, plasticizers,
lubricants, dyes, and haze reducing agents.
[0029] More particularly, the non-ionic polyoxyethylene surfactants useful as coating aids
in the top-coat layer comprising the combination of the present invention can be represented
by the following formula:

wherein R₂ represents an alkyl group having 1 to 30 carbon atoms, an alkenyl group
having 1 to 30 carbon atoms or an aryl group having 6 to 30 ring atoms (such as phenyl
or naphthyl) or a combination thereof, R₃ represents a hydrogen atom or a methyl group,
D represents a group -O-, -S-, -COO-, -NR₄-, -CO-NR₄-, or -SO₂-NR₄-, wherein R₄ represents
a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, q represents 0 or 1
and r represents an integer of 2 to 50.
[0030] Examples of non-ionic polyoxyalkylene surfactants are illustrated below.

The non-ionic polyoxyalkylene surfactants are employed in an amount of from 10
to 200 mg/m², preferably from 20 to 150 mg/m², more preferably from 30 to 120 mg/m²
of top-coat protective layer.
[0031] Anionic polyoxyethylene surfactants, normally used in photography, are surfactants
of the type including a polyoxyethylene group linked to an anionic hydrophilic group
and to a hydrocarbon residue directly or by means of a bridge consisting of a divalent
organic residue, as expressed by the following formula:

wherein R is an aliphatic, aromatic or a mixed hydrocarbon residue and preferably
a linear or branched alkyl group having from 4 to 18 carbon atoms or an aryl group
substituted with one or more alkyl groups altogether having from 4 to 18 carbon atoms,A
is a divalent organic residue, preferably a carbonyl, a sulfonyl, an amino or an alkylene
group preferably having from 1 to 3 carbon atoms, an oxygen atom or groups consisting
of two or more of the above-mentioned groups, such as for example carbonylamino, sulfonylamino,
aminocarbonyl, aminosulfonyl, or ester, X is an anionic group selected from the class
consisting of sulfonate group, carboxylate group, phosphate group and sulfate group,
[0032] Me is an alkaline or alkaline-earth metal, such as Na, K, Li, Ca, Mg, and the like,
and m is 0 or 1 and n is an integer of from 1 to 25.Anionic surface active agents
of this type are described for example in Schwarz et al. "Surface Active Agents and
Detergents", Vol. I and II, Interscience Publ., in the US Pat. Nos. 2,992,108, 3,068,101,
3,201,152 and 3,165,409, in the French Pat. Nos. 1,556,240 and 1,497,930 and in the
British Pat. Nos. 580,504 and 985,483.Examples of anionic polyoxyethylene surfactants
useful in the combination of the present invention are listed hereinbelow.
C₁₂H₂₅―O―(CH₂CH₂O)₂-SO₃⁻ Na⁺
C₁₈H₃₇―SO₂-NH―(CH₂CH₂O)₄―SO₃⁻ Na⁺

The anionic polyoxyalkylene surfactants are employed in an amount of from from
10 to 200 mg/m², preferably from 20 to 100 mg/m², more preferably from 30 to 80 mg/m²
of top-coat protective layer.
[0033] Alkylsulfate surfactants, normally used in photography, are surfactants of the type
including an alkyl group linked to a sulfate group through an oxygen atom, as expressed
by the following formula:

wherein R is an aliphatic group and preferably a linear or branched alkyl group having
from 4 to 18 carbon atoms, and Me is an alkali metal, such as Na, K, Li.
[0034] The alkylsulfate surfactants are employed in an amount of from 10 to 200 mg/m², preferably
from 10 to 100 mg/m², more preferably from 10 to 50 mg/m² of top-coat protective layer.
[0035] Photographic materials according to the invention generally comprise at least one
light sensitive layer, such as a silver halide emulsion layer, coated on at least
one side of a support. Silver halide emulsions typically comprise silver halide grains
which may have different crystal forms and sizes, such as, for example, cubic grains,
octahedral grains, tabular grains, spherical grains and the like. Tabular grains are
preferred. The tabular silver halide grains contained in the silver halide emulsion
layers of this invention have an average diameter:thickness ratio (often referred
to in the art as aspect ratio) of at least 3:1, preferably 3:1 to 20:1, more preferably
3:1 to 14:1, and most preferably 3:1 to 8:1. Average diameters of the tabular silver
halide grains suitable for use in this invention range from about 0.3 to about 5 µm,
preferably 0.5 to 3 µm, more preferably 0.8 to 1.5 µm. The tabular silver halide grains
suitable for use in this invention have a thickness of less than 0.4 µm, preferably
less than 0.3 µm and more preferably less than 0.2 µm. The tabular silver halide grain
characteristics described above can be readily ascertained by procedures well known
to those skilled in the art. The term "diameter" is defined as the diameter of a circle
having an area equal to the projected area of the grain. The term "thickness" means
the distance between two substantially parallel main planes constituting the tabular
silver halide grains. From the measure of diameter and thickness of each grain the
diameter:thickness ratio of each grain can be calculated, and the diameter:thickness
ratios of all tabular grains can be averaged to obtain their average diameter:thickness
ratio. By this definition the average diameter:thickness ratio is the average of individual
tabular grain diameter:thickness ratios. In practice, it is simpler to obtain an average
diameter and an average thickness of the tabular grains and to calculate the average
diameter:thickness ratio as the ratio of these two averages. Whatever the used method
may be, the average diameter:thickness ratios obtained do not greatly differ. In the
silver halide emulsion layer containing tabular silver halide grains of the invention,
at least 15%, preferably at least 25%, and, more preferably, at least 50% of the silver
halide grains are tabular grains having an average dia-meter:thickness ratio of not
less than 3:1. Each of the above proportions, "15%", "25%" and "50%" means the proportion
of the total projected area of the tabular grains having a diameter:thickness ratio
of at least 3:1 and a thickness lower than 0.4 µm, as compared to the projected area
of all of the silver halide grains in the layer. Other conventional silver halide
grain structures such as cubic, orthorhombic, tetrahedral, etc. may make up the remainder
of the grains. In the present invention, commonly employed halogen compositions of
the silver halide grains can be used. Typical silver halides include silver chloride,
silver bromide, silver iodide, silver chloroiodide, silver bromoiodide, silver chloro-bromoiodide
and the like. However, silver bromide and silver bromoiodide are preferred silver
halide compositions for tabular silver halide grains with silver bromoiodide compositions
containing from 0 to 10 mol% silver iodide, preferably from 0.2 to 5 mol% silver iodide,
and more preferably from 0.5 to 1.5% mol silver iodide. The halogen composition of
individual grains may be homogeneous or heterogeneous. Silver halide emulsions containing
tabular silver halide grains can be prepared by various processes known for the preparation
of photographic materials. Silver halide emulsions can be prepared by the acid process,
neutral process or ammonia process. In the stage for the preparation, a soluble silver
salt and a halogen salt can be reacted in accordance with the single jet process,
double jet process, reverse mixing process or a combination process by adjusting the
conditions in the grain formation, such as pH, pAg, temperature, form and scale of
the reaction vessel, and the reaction method. A silver halide solvent, such as ammonia,
thioethers, thioureas, etc., may be used, if desired, for controlling grain size,
form of the grains, particle size distribution of the grains, and the grain-growth
rate. Preparation of silver halide emulsions containing tabular silver halide grains
is described, for example, in de Cugnac and Chateau, "Evolution of the Morphology
of Silver Bromide Crystals During Physical Ripening", Science and Industries Photographiques,
Vol. 33, No.2 (1962), pp. 121-125, in Gutoff, "Nucleation and Growth Rates During
the Precipitation of Silver Halide Photographic Emulsions", Photographic Science and
Engineering, Vol. 14, No. 4 (1970), pp. 248-257, in Berry et al., "Effects of Environment
on the Growth of Silver Bromide Microcrystals", Vol.5, No.6 (1961), pp. 332-336, in
US Pat. Nos. 4,063,951, 4,067,739, 4,184,878, 4,434,226, 4,414,310, 4,386,156, 4,414,306
and in EP Pat. Appl. No. 263,508. As a binder for silver halide emulsions and other
hydrophilic colloid layers, gelatin is preferred, but other hydrophilic colloids can
be used, alone or in combination, such as, for example, dextran, cellulose derivatives
(e.g.,hydroxyethylcellulose, carboxymethyl cellulose), collagen derivatives, colloidal
albumin or casein, polysaccharides, synthetic hydrophilic polymers (e.g., polyvinylpyrrolidone,
polyacrylamide, polyvinylalcohol, polyvinylpyrazole) and the like. Gelatin derivatives,
such as, for example, highly deionized gelatin, acetylated gelatin and phthalated
gelatin can also be used. Highly deionized gelatin is characterized by a higher deionization
with respect to the commonly used photographic gelatins. Preferably, highly deionized
gelatin is almost completely deionized which is defined as meaning that it presents
less than 50 ppm (parts per million) of Ca⁺⁺ ions and is practically free (less than
5 parts per million) of other ions such as chlorides, phosphates, sulfates and nitrates,
compared with commonly used photographic gelatins having up to 5,000 ppm of Ca⁺⁺ ions
and the significant presence of other ions. The amount of gelatin employed in the
light-sensitive photographic material of the present invention is such as to provide
a total silver to gelatin ratio lower than 1 (expressed as grams of Ag/grams of gelatin).
In particular the silver to gelatin ratio of the silver halide emulsion layers is
in the range of from 1 to 1.5. Silver halide emulsion layers can be sensitized to
a particular range of wavelengths with a sensitizing dye. Typical sensitizing dyes
include cyanine, hemicyanine, merocyanine, oxonols, hemioxonols, styryls, merostyryls
and streptocyanines. The silver halide photographic material of the present invention
can have one or more silver halide emulsion layers sensitized to the same or different
regions of the electromagnetic spectrum. The silver halide emulsion layers can be
coated on one side or on both side of a support base.
[0036] Examples of materials suitable for the preparation of the support include glass,
paper, polyethylene-coated paper, metals, polymeric film such as cellulose nitrate,
cellulose acetate, polystyrene, polyethylene terephthalate, polyethylene, polypropylene
and the like. Specific photographic materials according to the invention are black-and-white
light-sensitive photographic materials, in particular X-ray light-sensitive materials.
Preferred light-sensitive silver halide photographic materials according to this invention
are radiographic light-sensitive materials employed in X-ray imaging comprising a
silver halide emulsion layer(s) coated on one surface, preferably on both surfaces
of a support, preferably a polyethylene terephthalate support. Preferably, the silver
halide emulsions are coated on the support at a total silver coverage in the range
of 3 to 6 grams per square meter. Usually, the radiographic light-sensitive materials
are associated with intensifying screens so as to be exposed to radiation emitted
by said screens. The screens are made of relatively thick phosphor layers which transform
the X-rays into more imaging-effective radiation such as light (e.g., visible light).
The screens absorb a much larger portion of X-rays than the light-sensitive materials
do and are used to reduce the X-ray dose necessary to obtain a useful image. According
to their chemical composition, the phosphors can emit radiation in the ultraviolet,
blue, green or red region of the visible spectrum and the silver halide emulsions
are sensitized to the wavelength region of the radiation emitted by the screens. Sensitization
is performed by using spectral sensitizing dyes absorbed on the surface of the silver
halide grains as known in the art. More preferred light-sensitive silver halide photographic
materials according to this invention are radiographic light-sensitive materials which
employ intermediate diameter:thickness ratio tabular grain silver halide emulsions,
as disclosed in US 4,425,426 and in EP Pat. Appl. 84,637.
[0037] However other black-and-white photographic materials, such as lithographic light-sensitive
materials, black-and-white photographic printing papers, black-and-white negative
films, as well as light-sensitive photographic color materials such as color negative
films, color reversal films, color papers, etc. can benefit of the use of the present
invention. The light sensitive layers intended for use in color photographic material
contain or have associated therewith dye-forming compounds or couplers. For example,
a red-sensitive emulsion would generally have a cyan coupler associated therewith,
a green-sensitive emulsion would generally have a magenta coupler associated therewith,
and a blue-sensitive emulsion would generally have a yellow coupler associated therewith.
The silver halide photographic materials of the present invention are fore-hardened.
Typical examples of organic or inorganic hardeners include chrome salts (e.g., chrome
alum, chromium acetate), aldehydes (e.g., formaldehyde and glutaraldehyde), isocyanate
compounds (hexamethylene diisocyanate), active halogen compounds (e.g., 2,4-dichloro-6-hydroxy-s-triazine),
epoxy compounds (e.g., tetramethylene glycol diglycidylether), N-methylol derivatives
(e.g., dimethylolurea, methyloldimethyl hydantoin), aziridines, mucohalogeno acids
(e.g., mucochloric acid), active vinyl derivatives (e.g., vinylsulfonyl arid hydroxy
substituted vinylsulfonyl derivatives) and the like. Other references to well known
hardeners can be found in
Research Disclosure, December 1989, Vol. 308, Item 308119, Section X. Other layers and additives, such
as subbing layers, surfactants, filter dyes, intermediate layers, protective layers,
anti-halation layers, barrier layers, development inhibiting compounds, speed-increasing
agent, stabilizers, plasticizer, chemical sensitizer, UV absorbers and the like can
be present in the photographic element. A detailed description of photographic elements
and of various layers and add tives can be found in Research Disclosure 17643 December
1978, 18431 August 1979, 18716 November 1979, 22534 January 1983, and 308119 December
1989. The silver halidephotographic material of the present invention can be exposed
and processed by any conventional processing technique. Any known developing agent
can be used into the developer, such as, for example, dihydroxybenzenes (e.g., hydroquinone),
pyrazolidones (1-phenyl-3-pyrazo-lidone-4,4-dimethyl-1-phenyl-3-pyrazolid-one), and
aminophenols (e.g., N-meth-yl-p-aminophenol), alone or in combinations thereof. Preferably
the silver halide photographic materials are developed in a developer comprising dihydroxy-benzenes
as the main developing agent, and pyrazolidones and p-aminophenols as auxiliary developing
agents. Other well known additives can be present in the developer, such as, for example,
antifoggants (e.g., benzotriazoles, indazoles, tetrazoles), silver halide solvents
(e.g., thiosulfates, thiocyanates), sequestering agents (e.g., aminopolycarboxylic
acids, aminopolyphosphonic acids), sulfite antioxidants, buffers, restrainers, hardeners,
contrast promoting agents, surfactants, and the like. Inorganic alkaline agents, such
as KOH, NaOH, and LiOH are added to the developer composition to obtain the desired
pH which is usually higher than 10. The silver halide photographic material of the
present invention can be processed with a fixer of typical composition. The fixing
agents include thiosulfates, thiocyanates, sulfites, ammonium salts, and the like.
The fixer composition can comprise other well known additives, such as, for example,
acid compounds (e.g., metabisulfates), buffers (e.g., carbonic acid, acetic acid),
hardeners (e.g., aluminum salts), tone improving agents, and the like. The present
invention is particularly intended and effective for high temperature, accelerated
processing with automatic processors where the photographic element is transported
automatically and at constant speed from one processing unit to another by means of
roller. Typical examples of said automatic processors are 3M TRIMATIC™ XP515 and KODAK
RP X-OMAT™. The processing temperature ranges from 20° to 60°C, preferably from 30°
to 50°C and the processing time is lower than 90 seconds, preferably lower than 45
seconds. The good antistatic and surface characteristics of the silver halide photographic
material of the present invention allow the rapid processing of the material without
having the undesirable appearance of static marks or scratches on the surface of the
film. The invention will be described hereinafter by reference to the following example.
EXAMPLE 1
[0038] A tabular grain silver bromide emulsion (having an average dia-meter:thickness ratio
of about 7.6:1, prepared in the presence of a deionized gelatin having a viscosity
at 60°C in water at 6.67% w/w of 4.6 mPas, a conducibility at 40°C in water at 6.67%
w/w of less than 150 µs/cm and less than 50 ppm of Ca⁺⁺) was optically sensitized
to green light with a cyanine dye and chemically sensitized with sodium p-toluenethiosulfonate,
sodium p-toluenesulfinate and benzothiazoleiodoethylate. At the end of the chemical
digestion, non-deionized gelatin (having a viscosity at 60°C in water at 6.67% w/w
of 5.5 mPas, a conducibility at 40°C in water at 6.67% w/w of 1,100 µs/cm and 4,500
ppm of Ca⁺⁺) was added to the emulsion in an amount to have 83% by weight of deionized
gelatin and 17% by weight of non-deionized gelatin. The emulsion, containing 5-methyl-7-hydroxy-triazaindolizine
stabilizer and a hardener, was divided into twelve portions. Each portion was coated
on each side of a blue polyester film support at a silver coverage of 2.15 g/m² and
a gelatin coverage of 1.5 g/m² per side. A non-deionized gelatin protective supercoat
containing 1.01 g/m² of gelatin per side and the compounds indicated in Table 1 was
applied on each coating so obtaining seventeen different double-side radiographic
films 1 to 17.
TABLE 1
Sample |
Triton™ X-100 mg/m² |
Triton™ X-200 mg/m² |
Zonyl ™ FSN mg/m² |
Compound A mg/m² |
Compound B mg/m² |
Compound C mg/m² |
Note |
1 |
50 |
105 |
|
|
|
|
control |
2 |
50 |
70 |
|
|
|
|
control |
3 |
50 |
105 |
|
40 |
|
|
control |
4 |
50 |
105 |
|
|
40 |
|
control |
5 |
50 |
105 |
40 |
|
|
|
control |
6 |
50 |
105 |
|
|
|
40 |
control |
7 |
50 |
105 |
|
70 |
|
|
control |
8 |
50 |
105 |
|
|
70 |
|
control |
9 |
50 |
105 |
40 |
|
40 |
|
invention |
10 |
50 |
105 |
|
|
40 |
40 |
invention |
11 |
50 |
70 |
40 |
40 |
|
|
invention |
12 |
50 |
70 |
40 |
|
40 |
|
invention |
13 |
50 |
70 |
|
|
40 |
40 |
invention |
14 |
50 |
40 |
|
|
40 |
70 |
invention |
15 |
50 |
10 |
|
|
40 |
80 |
invention |
16 |
50 |
105 |
|
|
20 |
40 |
invention |
17 |
50 |
105 |
|
|
10 |
40 |
invention |
[0039] Compound A is a perfluoromethylsulfonylmethide lithium salt having the following
formula:

compound B is a perfluoromethylsulfonylimide lithium salt having the following formula:

compound C is a non-ionic perfluoroalkylenepolyoxyethylene surfactant having the following
formula:

Triton™ X-200 is the trade name of an anionic surfactant of the alkylphenyloxyethylene
sulfonate type having the following formula:

Triton™ X-100 is the trade name of a non-ionic surfactant of the alkylphenoxyethylene
type having the following formula:

Zonyl™ FSN is the trade name of a non-ionic surfactant of the perfluoroalkylpolyoxyethylene
type, manufactured by DuPont and having the following formula:

wherein x is an integer from 10 to 20.
[0040] The samples 1 to 17 were conditioned for 160 minutes at 70°C and 40% of relative
humidity to evaluate the sensitometric properties, and for 15 hours at 50°C and 20%
relative humidity to evaluate the physical properties. After conditioning, the samples
were exposed and developed. The samples were then evaluated according to the following
tests.
CHARGE DECAY TIME TEST
[0041] According to this test, the static charge dissipation of each of the films was measured.
The films were cut into 45x54mm samples and conditioned at 25% relative humidity and
T=21°C for 15 hours. The charge decay time was measured with a Charge Decay Test Unit
JCI 155 (manufactured by John Chubb Ltd., London). This apparatus deposits a charge
on the surface of the film by a high voltage corona discharge and a fieldmeter allows
observation of the decay time of the surface voltage. The lower the time, the better
the antistatic properties of the film. To prevent the charge decay behavior of the
tested surface from being influenced by the opposite surface, this surface was grounded
by contacting it with a metallic back surface.
SURFACE RESISTIVITY TEST
[0042] According to this test the resistivity of the sample surface was measured using the
Hewlett Packard model 4329A high resistance meter. The lower the value, the better
the antistatic protection of the film.
SLIPPERINESS TEST
[0043] This test was performed with a Lhomargy apparatus. It consists of a slide moving
on the film at a speed of about 15 cm/min. A force transducer connected to the slide
transforms the applied force into an amplified DC voltage which is recorded on a paper
recorder. The force applied to start the sliding movement represents the value of
static slipperiness. The movement of the slide on the film is not continuous. The discontinuity of the
movement can be measured (in terms of slipperiness difference) from the graph of the
paper recorder. This value represents the
dynamic slipperiness. It was noted that the more the movement was discontinuous (i.e., the higher the value
of slipperiness difference), the better was the performance of the film.
[0044] The results of the above mentioned tests are summarized in the following Table 2.
TABLE 2
Physical properties |
Sample |
Decay Time (sec) |
Surface Resistivity (Ω/cm²) |
Static Slipperiness |
Dynamic Slipperiness |
NOTE |
1 |
184 |
9.4*10¹² |
130 |
114 |
Control |
2 |
215 |
9.8*10¹² |
138 |
116 |
Control |
3 |
234 |
1.0*10¹³ |
124 |
95 |
Control |
4 |
319 |
1.3*10¹³ |
150 |
120 |
Control |
5 |
108 |
4.1*10¹² |
144 |
90 |
Control |
6 |
105 |
6.0*10¹² |
112 |
86 |
Control |
7 |
487 |
1.6*10¹³ |
103 |
92 |
Control |
8 |
437 |
1.5*10¹³ |
118 |
111 |
Control |
9 |
49 |
2.8*10¹² |
142 |
85 |
Invention |
10 |
12 |
7.9*10¹¹ |
130 |
96 |
Invention |
11 |
130 |
5.4*10¹² |
97 |
75 |
Invention |
12 |
55 |
3.6*10¹² |
102 |
68 |
Invention |
13 |
28 |
1.7*10¹² |
137 |
95 |
Invention |
14 |
25 |
1.1*10¹² |
138 |
107 |
Invention |
15 |
38 |
1.9*10¹² |
137 |
107 |
Invention |
16 |
14 |
8.1*10¹¹ |
142 |
98 |
Invention |
17 |
14 |
8.2*10¹¹ |
129 |
98 |
Invention |
[0045] Samples 9 to 17 of the invention give the best results in terms of decay time and
surface resistivity. In particular, samples 16 and 17 comprising compound C and compound
B give the best results.
[0046] In the following Table 3 are summarized the sensitometric characteristics of samples
1 to 17. The presence of the antistatic layer of the present invention does not adversely
affect the good sensitometric characteristics of the silver halide materials.
TABLE 3
Sensitometry |
Sample |
D.min |
D.max |
Speed |
Contrast |
NOTE |
1 |
0.15 |
1.53 |
2.55 |
1.41 |
Control |
2 |
0.15 |
1.61 |
2.51 |
1.46 |
Control |
3 |
0.15 |
1.55 |
2.51 |
1.45 |
Control |
4 |
0.15 |
1.65 |
2.51 |
1.45 |
Control |
5 |
0.15 |
1.66 |
2.51 |
1.49 |
Control |
6 |
0.15 |
1.62 |
2.46 |
1.59 |
Control |
7 |
0.15 |
1.58 |
2.52 |
1.46 |
Control |
8 |
0.15 |
1.53 |
2.56 |
1.43 |
Control |
9 |
0.15 |
1.66 |
2.49 |
1.48 |
Invention |
10 |
0.15 |
1.58 |
2.55 |
1.41 |
Invention |
11 |
0.15 |
1.58 |
2.57 |
1.49 |
Invention |
12 |
0.15 |
1.52 |
2.57 |
1.41 |
Invention |
13 |
0.15 |
1.56 |
2.54 |
1.45 |
Invention |
14 |
0.16 |
1.57 |
2.52 |
1.44 |
Invention |
15 |
0.16 |
1.52 |
2.52 |
1.34 |
Invention |
16 |
0.16 |
1.55 |
2.54 |
1.49 |
Invention |
17 |
0.16 |
1.49 |
2.58 |
1.34 |
Invention |
EXAMPLE 2
[0047] A tabular grain silver bromide emulsion (having an average dia-meter:thickness ratio
of about 7.6:1, prepared in the presence of a deionized gelatin having a viscosity
at 60°C in water at 6.67% w/w of 4.6 mPas, a conducibility at 40°C in water at 6.67%
w/w of less than 150 µs/cm and less than 50 ppm of Ca⁺⁺) was optically sensitized
to green light with a cyanine dye and chemically sensitized with sodium p-toluenethiosulfonate,
sodium p-toluene-sulfinate and benzothiazoleiodoethylate. At the end of the chemical
digestion, non-deionized gelatin (having a viscosity at 60°C in water at 6.67% w/w
of 5.5 mPas, a conducibility at 40°C in water at 6.67% w/w of 1,100 µs/cm and 4,500
ppm of Ca⁺⁺) was added to the emulsion in an amount to have 83% by weight of deionized
gelatin and 17% by weight of non-deionized gelatin. The emulsion, containing 5-methyl-7-hydroxy-triazaindozine
stabilizer and a hardener, was divided into twelve portions. Each portion was coated
on each side of a blue polyester film support at a silver coverage of 2.15 g/m² and
a gelatin coverage of 1.5 g/m² per side. A non-deionized gelatin protective supercoat
containing 1.01 g/m² of gelatin per side, 16mg/m² of Tergitol™ 4 as coating aid, and
the compounds indicated in Table 4 was applied on each coating so obtaining twelve
different double-side radiographic films 1 to 9. Tergitol™ 4 is the trade name of
an alkylsulfate surfactant manufactured by Union Carbide.
TABLE 4
Sample |
Compound 1 mg/m² |
Zonyl™ FSN mg/m² |
Silwet™ L-7605 mg/m² |
NOTE |
1 |
13 |
/ |
/ |
Control |
2 |
/ |
52 |
/ |
Control |
3 |
/ |
/ |
20 |
Control |
4 |
13 |
52 |
/ |
Invention |
5 |
13 |
/ |
39 |
Invention |
6 |
13 |
52 |
39 |
Invention |
7 |
13 |
52 |
20 |
Invention |
8 |
13 |
52 |
7 |
Invention |
9 |
26 |
90 |
39 |
Invention |
compound 1 is a perfluoromethylsulfonylimide lithium salt having the following formula:

Silwet™ L-7605 is the trade name of a polyalkyleneoxide-modified dimethylpolysiloxane
surfactant manufactured by Union Carbide and having the following formula:

wherein m ranges from 5 to 100, n ranges from 2 to 50, p ranges from 5 to 50, and
q ranges from 0 to 50.
[0048] The samples 1 to 9 were conditioned for 160 minutes at 70°C and 40% of relative humidity
to evaluate the sensitometric properties, and for 15 hours at 50°C and 20% relative
humidity to evaluate the physical properties. After conditioning the samples were
exposed and developed. The samples were then evaluated according to the same tests
of Example 1.
[0049] The results of the tests are summarized in the following Table 5.
TABLE 5
Physical properties |
Sample |
Decay Time (sec) |
Surface Resistivity (Ω/cm²) |
Static Slipperiness |
Dynamic Slipperiness |
NOTE |
1 |
104 |
5.83*10¹² |
102 |
80 |
Control |
2 |
81 |
3.62*10¹² |
84 |
50 |
Control |
3 |
137 |
5.93*10¹² |
107 |
86 |
Control |
4 |
46 |
2.21*10¹² |
78 |
47 |
Invention |
5 |
48 |
3.6*10¹² |
81 |
63 |
Invention |
6 |
25 |
1.44*10¹² |
78 |
50 |
Invention |
7 |
24 |
1.26*10¹² |
73 |
51 |
Invention |
8 |
26 |
1.41*10¹² |
74 |
44 |
Invention |
9 |
10 |
3.40*10¹¹ |
62 |
42 |
Invention |
[0050] The combination of the present invention gives a strong improvement in all the antistatic
characteristics of the photographic material, without adversely affect the sensitometric
results, as showed in the following table 6.
TABLE 6
Sensitometry |
Sample |
D.min |
D.max |
Speed |
Contrast |
NOTE |
1 |
0.20 |
3.62 |
2.24 |
2.73 |
Control |
2 |
0.20 |
3.61 |
2.27 |
2.67 |
Control |
3 |
0.21 |
3.67 |
2.27 |
2.70 |
Control |
4 |
0.20 |
3.65 |
2.27 |
2.61 |
Invention |
5 |
0.20 |
3.66 |
2.28 |
2.60 |
Invention |
6 |
0.20 |
3.51 |
2.29 |
2.42 |
Invention |
7 |
0.20 |
3.68 |
2.27 |
2.71 |
Invention |
8 |
0.20 |
3.66 |
2.27 |
2.61 |
Invention |
9 |
0.20 |
3.88 |
2.25 |
2.63 |
Invention |
1. A silver halide photographic material comprising a support, at least one silver halide
emulsion layer coated thereon, and a hydrophilic colloid layer coated over said at
least one silver halide emulsion layer, wherein said hydrophilic colloid layer comprises
a combination of (a) at least one surfactant selected from the group consisting of
non-ionic perfluoroalkyl(ene)poly-oxyethylene surfactants and polyoxyethylene-modified
polysiloxane surfactants, and (b) at least one salt selected from the group of salts
of perfluoroalkylsulfonyl imides and perfluoroalkylsulfonyl methides.
2. The silver halide photographic material of claim 1, characterized in that said hydrophilic
colloid layer further comprises at least one surfactant selected from the group consisting
of (a) non-ionic polyoxyethylene surfactants, (b) anionic polyoxyethylene surfactants,
and (c) alkylsulfate surfactants.
3. The silver halide photographic material according to claim 1 or 2 characterized in
that said non-ionic perfluoroalkyl(ene)polyoxyethylene surfactant is represented by
the following formula:

wherein Rf can be a perfluoroalkyl group, a perfluoroalkylene group, a perfluorocycloalkyl
group, and a perfluorocycloalkylene group having from 4 to 16 carbon atoms, X can
be -O-, -SO₂NR''-, -CONR'', -CH₂O-, or a single bond, R, R' and R'' are, independently,
hydrogen or a lower alkyl of from 1 to 4 carbon atoms, and y is a number from 6 to
30.
4. The silver halide photographic material according to claim 1 or 2 characterized in
that said polyoxyethylene modified-polysiloxane surfactant is represented by the following
formula:

wherein R is a lower alkyl having from 1 to 4 carbon atoms, R' is a lower alkylene
having from 1 to 4 carbon atoms, R'' is hydrogen or a lower alkyl of from 1 to 4 carbon
atoms, m is an integer from 5 to 100, n is an integer from 2 to 50, p is an integer
from 5 to 50, and q is an integer from 0 to 50.
5. The silver halide photographic material according to claim 1 or 2 characterized in
that said salt of perfluoroalkylsulfonyl imide or perfluoro-alkylsulfonyl methide
is represented by the following formula:

wherein Rf is a fluorinated alkyl group having 1 to 10 carbon atoms, X is nitrogen
or carbon atom, M is an organic or inorganic cation, and v is the X valence, and wherein
two Rf groups can join together to form a ring.
6. The silver halide photographic material according to claim 5 characterized in that
M is selected from the group consisting of alkali metal cations, alkaline-earth metal
cations, alkylammonium, and quaternary ammonium cations.
7. The silver halide photographic material according to claim 5 characterized in that
M is a lithium cation.
8. The silver halide photographic material according to claim 2 characterized in that
said non-ionic polyoxyethylene surfactant is represented by the following formula:

wherein R₂ represents an alkyl group having 1 to 30 carbon atoms, an alkenyl group
having 1 to 30 carbon atoms or an aryl group having 6 to 30 ring atoms or a combination
thereof, R₃ represents a hydrogen atom or a methyl group, D represents a group -O-,
-S-, -COO-, -NR₄-, -CO-NR₄-, or -SO₂-NR₄-, wherein R₄ represents a hydrogen atom or
an alkyl group having 1 to 12 carbon atoms, q represents 0 or 1 and r represents an
integer of 2 to 50.
9. The silver halide photographic material according to claim 2 characterized in that
said anionic polyoxyethylene surfactant is represented by the following formula:

wherein R is an aliphatic, aromatic or a mixed hydrocarbon residue and preferably
a linear or branched alkyl group having from 4 to 18 carbon atoms or an aryl group
substituted with one or more alkyl groups altogether having from 4 to 18 carbon atoms,
A is a divalent organic residue, preferably a carbonyl, a sulfonyl, an amino or an
alkylene group preferably having from 1 to 3 carbon atoms, an oxygen atom or groups
consisting of two or more of the above-mentioned groups, such as for example carbonylamino,
sulfonylamino, aminocarbonyl, aminosulfonyl, or ester, X is an anionic group selected
from the class consisting of sulfonate group, carboxylate group, phosphate group and
sulfate group,
Me is an alkali or alkaline-earth metal, and m is 0 or 1 and n is an integer of
from 1 to 25.
10. The silver halide photographic material according to claim 2 characterized in that
said alkylsulfate surfactant is represented by the following formula:

wherein R is a linear or branched alkyl group having from 4 to 18 carbon atoms, and
Me is an alkali metal.
11. The silver halide photographic material according to claim 1 or 2 characterized in
that said salt of perfluoroalkylsulfonyl imide or perfluoro-alkylsulfonyl methide
is present in an amount of from 1 to 100 mg/m² of top-coat protective layer.
12. The silver halide photographic material according to claim 1 or 2 characterized in
that said non-ionic perfluoroalkyl(ene)polyoxyethylene surfactant is present in an
amount of from 10 to 100 mg/m² of top-coat protective layer.
13. The silver halide photographic material according to claim 1 or 2 characterized in
that said polyoxyethylene-modified polysiloxane surfactants is present in an amount
of from 1 to 100 mg/m² of top-coat protective layer.
14. The silver halide photographic material according to claim 2 characterized in that
each of said surfactants selected from the group consisting of non-ionic polyoxyethylene
surfactants, anionic polyoxyethylene surfactants, and alkylsulfate surfactants are
present in an amount of from 10 to 200 mg/m² of top-coat protective layer.
15. A silver halide photographic material comprising a support, at least one silver halide
emulsion layer coated thereon, and a hydrophilic colloid layer coated on said at least
one silver halide emulsion layer, wherein said hydrophilic colloid layer comprises
a combination of (a) a non-ionic perfluoroalkyl(ene)poly-oxyethylene surfactants,
(b) a polyoxyethylene-modified polysiloxane surfac-tants, and (c) at least one salt
selected in the group of salts of perfluoroalkylsulfonyl imide and perfluoroalkylsulfonyl
methide.