Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
  • G03C1/08—Sensitivity-increasing substances
  • G03C1/28—Sensitivity-increasing substances together with supersensitising substances
  • G03C1/29—Sensitivity-increasing substances together with supersensitising substances the supersensitising mixture being solely composed of dyes ; Combination of dyes, even if the supersensitising effect is not explicitly disclosed
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
  • G03C1/08—Sensitivity-increasing substances
  • G03C1/09—Noble metals or mercury; Salts or compounds thereof; Sulfur, selenium or tellurium, or compounds thereof, e.g. for chemical sensitising
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
  • G03C1/08—Sensitivity-increasing substances
  • G03C1/10—Organic substances
  • G03C1/12—Methine and polymethine dyes
  • G03C1/14—Methine and polymethine dyes with an odd number of CH groups
  • G03C1/16—Methine and polymethine dyes with an odd number of CH groups with one CH group

Definitions

• This invention relates to a photographic element, in particular to a photographic element comprising a silver halide emulsion layer containing at least two sensitizing dyes.
• Photographic elements typically contain a light sensitive silver halide emulsion layer sensitive to blue light.
• a sensitizing dye is generally used to provide the desired sensitivity to blue light.
• Dyes used for this purpose tend to be water insoluble and are added to a silver halide emulsion in a water/alcohol solution.
• a problem that arises with this procedure is crystallization of the dye. because of this, larger amounts of dye must be used to ensure the desired degree of sensitivity. Also crystallization of the dye poses difficulties in manufacture of photographic elements, e.g., plugging filters used to purify the emulsion prior to coating the emulsion on a support.
• the components used can result in undesirable results.
• certain gold compounds react with gelatin which results in variability from batch to batch.
• Photographic elements typically contain a light sensitive silver halide emulsion layer sensitive to blue light.
• a sensitizing dye is generally used to provide the desired sensitivity to blue light.
• Dyes used for this purpose tend to be water insoluble and are added to a silver halide emulsion in a water/alcohol solution.
• a problem that arises with this procedure is crystallization of the dye. because of this, larger amounts of dye must be used to ensure the desired degree of sensitivity. Also crystallization of the dye poses difficulties in manufacture of photographic elements, e.g., plugging filters used to purify the emulsion prior to coating the emulsion on a support.
• the components used can result in undesirable results.
• certain gold compounds react with gelatin which results in variability from batch to batch.
• This invention also addresses the problems encountered in the manufacture of a photographic element, in particular, the problems of crystallization of the sensitizing dye, reaction of the gold compound with gelatin and optimizing the relative amounts of gold and sulfur used to chemically sensitize the silver halide.
• One aspect of this invention comprises a photographic element comprising at least one silver halide emulsion layer in which:
• the silver halide is chemically senstized with a gold(I) compound of formula (I) AuL 2 +X - or AuL(L 1 )+X - wherein
• the silver halide emulsion layer further comprises a disulfide compound of formula (II): wherein:
• This invention provides an adjustable sensitization envelope by the appropriate selection of the first and second dyes. Also, we have found much less speed loss when the first dye provides a maximum sensitization of 475 nm or less and the structural features of the dyes result in formation of a mixed aggregate.
• this invention (1) provides an adjustable sensitization envelope by the appropriate selection of the first and second dyes; (2) provides adjustable gold/sulfur chemical sensitization by use of appropriate amounts of a gold compound of formula (I) and a disulfide compound of formula (II) and (3) provides improved manufacturability.
• a silver halide emulsion is spectrally sensitized to blue light using a combination of two blue dyes.
• Preferred dyes are of the following classes: wherein Z 1 , Z 2 and Z" are independently a hydrogen or halogen atom or a substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aromatic, substituted or unsubstituted alkoxycarbonyl or substituted or unsubstituted heterocyclic group; and R 1 and R 2 , are independently substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl or substituted or unsubstituted aryl.
• At least one of R 1 and R 2 contains a water solubilizing group, such as sulfoalkyl, carboxyalkyl, sulfoaryl and the like.
• the dyes may also contain one or more substituents in other positions of the benzo ring.
• the approximate peak wavelength for each of the parent chromophores, when optimally substituted to enable aggregation, is shown.
• the pair of dyes which comprise the mixed aggregate as comprising a "long dye” and a “short dye” (i.e. dyes corresponding to the first and second dyes, respectively). Proceeding from top to bottom of Table A, adjacent pairs of long and short dyes will, when optimally substituted, form mixed aggregates.
• a dye with a maximum peak wavelength of about 470 nm will form a mixed aggregate with a dye with a maximum peak wavelength of about 450 nm or greater
• a dye with a maximum peak wavelength of about 450 nm will form a mixed aggregate with a dye with a peak wavelength of about 440 nm or greater
• so on down to a dye with a maximum peak wavelength of about 420 nm will form a mixed aggregate with a dye with a maximum peak wavelength of about 410 nm or greater.
• the differences in wavelengths between the short and long dyes determined by a ⁇ E that does not exceed 0.12 eV will range from about 15nm to about 25nm. Dyes need not be of different classes.
• a dye at the high end of the wavelength range for dyes of that class can be advantageously used with a dye at the low end of the wavelength range.
• a dye of class F having a peak wavelength of about 470 nm can be paired with a dye of class F having a peak wavelength of about 465 nm or less (not exceeding 0.12eV.)
• the dyes should be J-aggregating dyes which form a mixed aggregate when used in combination.
• substituents may be used to effect J-aggregation on predominantly AgBr emulsions.
• the dye is an oxacyanine, thiacyanine, oxacarbocyanine, or thiacarbocyanine
• alkyl group refers to a substituted or unsubstituted alkyl
• alkoxy refers to a substituted or unsubstituted alkoxy group
• aromatic substituent refers to a substituted or unsubstituted aromatic group
• heterocyclic substituent refers to a substituted or unsubstituted heterocyclic group.
• substituent groups usable on molecules herein include any groups, whether substituted or unsubstituted, which do not destroy properties necessary for the photographic utility.
• substituents on any of the mentioned groups can include known substituents, such as: halogen, for example, chloro, fluoro, bromo, iodo; alkoxy, particularly those "lower alkyl" (that is, with 1 to 6 carbon atoms, for example, methoxy, ethoxy; substituted or unsubstituted alkyl, particularly lower alkyl (for example, methyl, trifluoromethyl); thioalkyl (for example, methylthio or ethylthio), particularly either of those with 1 to 6 carbon atoms; substituted and unsubstituted aryl, particularly those having from 6 to 20 carbon atoms (for example, phenyl); and substituted or unsubstituted heteroaryl, particularly those having a 5 or 6-membered ring containing 1 to 3 heteroatoms selected from N, O, or S (for example, pyridyl, thienyl, furyl, pyrrolyl); acid or acid or
• Alkyl substituents may specifically include "lower alkyl” (that is, having 1-6 carbon atoms), for example, methyl, ethyl, and the like. Further, with regard to any alkyl group or alkylene group, it will be understood that these can be branched or unbranched and include ring structures.
• the invention can be achieved with dyes that: (a) for the two dyes with one allowed 5-position substituent, it must be aromatic in character; and (b) for the dyes with two allowed 5-position substituents, at least one of them must be aromatic in character.
• inventive and comparative dyes are shown in the following Table B. Note that the adjective "comparative" applies for these dyes only in reference to the AgCI emulsion; these dyes fail to aggregate or sustain the invention on this substrate. The predominant feature of this invention is that it applies to pairs of dyes rather than to single dyes.
• This invention describes the use of the combination of at least two blue sensitizing dyes having specifically different structures in combination with a silver halide emulsion so as to adjust the sensitization maximum of the element. This can afford improved color reproduction while maintaining high photographic sensitivity.
• Preferred combinations of dyes include, for example:
• blue dyes for use in this invention are of structures I and II defined below. wherein:
• a + and B + are counterions required to balance the net charge of the dye. Any positively charged counterion can be utilized. Common counterions that can be used include sodium, potassium, triethylammonium (TEA + ), tetramethylguanidinium (TMG + ), diisopropylammonium (DIPA + ), and tetrabutylammonium (TBA + ).
• the photographic element of the invention comprises a blue sensitive emulsion layer which has been chemically sensitized with a gold(I) compound of formula (Ia) or (Ib): AuL 2 + X - or AuL(L 1 ) + X - wherein
• the compounds may be soluble in any of a variety of solvents, including water or organic solvents such as acetone or methanol, but the most preferred compounds are water soluble.
• water soluble herein means that the gold(I) compound dissolves in water at the concentration of at least 10 -5 mole per liter of water at a temperature of 20° C at normal pressure.
• the mesoionic compound L herein is any such compound that can be coordinated with gold(I) ions to form a gold(I) compound that is water soluble and enables the described chemical sensitization of a photographic silver halide composition.
• the mesoionic compound is preferably represented by the formula: wherein the circle with the + sign on the heterocyclic ring symbolizes six delocalized ⁇ electrons associated with a partial positive charge on the heterocyclic ring.
• the a, b, c, d, and e represent the unsubstituted or substituted atoms necessary to complete the mesoionic compound, for example the carbon and nitrogen atoms necessary to complete mesoionic triazolium or tetrazolium 5-member heterocyclic ring.
• the members of the heterocyclic ring may be CR 5 or NR 5 ' groups or chalcogen atoms.
• the minus sign indicates two additional electrons on the exocyclic group f which are conjugated with the six ⁇ electrons on the heterocyclic ring. It is understood that there is extensive delocalization and that the charges indicated are only partial charges.
• the exocyclic group f may be S, Se, or NR 5 ".
• the groups R 5 , R 5 ' and R 5 " may be hydrogen atoms, substituted or unsubstituted alkyl, aryl, or heterocyclic groups, or R 5 , R 5 ' and R 5 " may link together by bonding to form another ring.
• Examples of the gold(I) compounds of the invention are given in the table below.
• the partial charges on the mesoionic ligands are dropped to avoid confusion with the overall charge of the complex ion.
• the rings symbolizing six delocalized ⁇ electrons on the heterocyclic moieties are retained, but will be understood not to imply aromaticity.
• R 6 , R 7 , and R 8 are independently a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, an amino group, a substituted or unsubstituted aryl group, and
• X - is a halogen or BF 4 - anion.
• gold(I) compounds are advantageous over certain other gold compounds containing sulfur known in the art such as trisodium aurous dithiosulfate because the compounds do not contain any labile S atoms, thus allowing independent choice and amount of S sensitizer, which is not possible with trisodium aurous dithiosulfate.
• the flexibility in choice and amount of sulfur sensitizer to be used in photographic emulsion is necessary in some cases to achieve proper gradation, reduced sensitivity to red light, and other sensitometric properties.
• the compounds of the present invention also are advantageous over other soluble gold(I) compounds which do not contain labile S atoms because the compounds have a lower dissociation constant and consequently have better solution stability.
• Alkyl or aryl thiolates for example, have a propensity to form polymeric gold(I) compounds with a 1:1 thiolate to gold formula.
• the compounds of this invention contain discrete gold(I) complexes possessing two ligands. Consequently, the compounds have solubility properties which are convenient for dispersion in the emulsion without requiring that a sulfonic acid or other solubilizing group be attached to the ligand.
• the compounds of the present invention also are advantageous over prior art gold(I) compounds is very convenient and does not involve potentially explosive material.
• the mesoionic compounds L used as starting materials to form the compounds with gold(I) may be made by methods described by Altland, Dedio and McSweeney, U.S. Pat. No. 4,378,424 (1983) or by methods described in the review article by Ollis and Ramsden cited above and references given therein. Synthesis of the gold(I) compounds can be effected by various techniques known to the art. One convenient method comprises reacting a gold(I) precursor compound with an appropriate amount of the mesoionic compound.
• the ligands of the gold(I) precursor compound are displaced by the mesoionic compounds, which have a higher affinity for gold(I).
• the product may then be isolated and purified by crystallization techniques.
• the various substituent groups on the mesoionic compound modify the solubility of the final product gold(I) compound.
• the most desired gold(I) compounds are those which are soluble in water and which may be made in water. Those which are soluble in organic solvents such as acetone can still be used to sensitize aqueous emulsions, and can be used to sensitize emulsions in non-aqueous media.
• the gold compounds are described in more detail in U.S. Patent No. 5,049,485, the entire disclosure of which is incorporated herein by reference.
• Disulfide compound used in the photographic element of this invention is preferably a compound represented by formula (II): wherein:
• Ar is an aromatic group either of a single ring or a condensed ring, preferably having 6 to 10 carbon atoms and more preferably having 6 carbon atoms. Examples of suitable aromatic groups include naphthyl and phenyl. Ar may be further substituted or may be unsubstituted, more preferably Ar is unsubstituted.
• substituents include alkyl groups (for example, methyl, ethyl, hexyl), fluoroalkyl groups (for example, trifluoromethyl), alkoxy groups (for example, methoxy, ethoxy, octyloxy), aryl groups (for example, phenyl, naphthyl, tolyl), hydroxyl groups, halogen atoms, aryloxy groups (for example, phenoxyl), alkylthio groups (for example, methylthio, butylthio), arylthio groups (for example, phenylthio), acyl groups (for example, acetyl, propionyl, butyryl, valeryl), sulfonyl groups (for example, methylsulfonyl, phenylsulfonyl), acylamino groups, sulfonylamino groups, acyloxy groups (for example, acetoxy, benzoxy), carb
• X' is independently an -O-, -NH- or -NR-. Most preferably X is -NH-. If X is -NR-, R is a substituent which does not interfere with the intended function of the disulfide compound in the photographic emulsion and which maintains the water soluability of the compound.
• suitable substituents include alkyl groups (for example, methyl, ethyl, hexyl), fluoroalkyl groups (for example, trifluoromethyl), aryl groups (for example, phenyl, naphthyl, tolyl), sulfonyl groups (for example, methylsulfonyl, phenylsulfonyl).
• Preferred are simple alkyl groups and simple fluoroalkyl groups.
• r and m are independently 0, 1 or 2. Therefore, included are those compounds in which only one of the aromatic groups is substituted. Preferably m and r are both 1.
• X' is independently in any position in the aromatic nucleus relative to the sulfur. More preferably, the molecule is symmetrical and preferably X' is either in the para or ortho position.
• L 2 is a linking group. p is 0 or 1.
• L 2 is a unsubstituted alkylene group and is usually -(CH 2 ) n - where n ranges from zero to 11 and is preferably 1 to 3.
• Other examples of L' are given below,
• M is either a hydrogen atom or a cationic species if the carboxyl group is in its ionized form.
• the cationic species may be a metal ion or an organic ion.
• organic cations include ammonium ions (for example, ammonium, tetramethylammonium, tetrabutylammonium), phosphonium ions (for example, tetraphenylphosphonium), and guanidyl groups.
• M is hydrogen or an alkali metal cation, with a sodium or potassium ion being most preferred.
• Examples of the disulfide compounds of this invention are shown below. Compounds I-A through I-H are preferred with Compounds I-D and I-E being most preferred.
• solubilized disulfides of this invention are easily prepared using readily available starting materials. Most of the solubilized disulfides can be obtained by reacting aminophenyl disulfide or hydroxyphenyl disulfide with the appropriate cyclic anhydride followed by conversion of the free diacid to its anionic form using materials such as sodium bicarbonate. Other solubilized disulfides could be obtained by reacting aminophenyl disulfide or hydroxyphenyl disulfide with the mono chloride of a dicarboxylic acid mono ester, followed by hydrolysis of the ester to the carboxylic acid. A discussion of these disulfide compounds can be found in U.S. Patent No. 5,418,127, the entire disclosure of which is incorporated herein by reference.
• the emulsion layer of the photographic element of the invention can comprise any one or more of the light sensitive layers of the photographic element.
• the photographic elements made in accordance with the present invention can be black and white elements, single color elements or multicolor elements.
• Multicolor elements contain dye image-forming units sensitive to each of the three primary regions of the spectrum. Each unit can be comprised of a single emulsion layer or of multiple emulsion layers sensitive to a given region of the spectrum.
• the layers of the element, including the layers of the image-forming units, can be arranged in various orders as known in the art.
• the emulsions sensitive to each of the three primary regions of the spectrum can be disposed as a single segmented layer.
• a typical multicolor photographic element comprises a support bearing a cyan dye image-forming unit comprised of at least one red-sensitive silver halide emulsion layer having associated therewith at least one cyan dye-forming coupler, a magenta dye image-forming unit comprising at least one green-sensitive silver halide emulsion layer having associated therewith at least one magenta dye-forming coupler, and a yellow dye image-forming unit comprising at least one blue-sensitive silver halide emulsion layer having associated therewith at least one yellow dye-forming coupler.
• the element can contain additional layers, such as filter layers, interlayers, overcoat layers, subbing layers, antihalation layers and the like. All of these can be coated on a support which can be transparent or reflective (for example, a paper support).
• Photographic elements of the present invention may also usefully include a magnetic recording material as described in Research Disclosure , Item 34390, November 1992, or a transparent magnetic recording layer such as a layer containing magnetic particles on the underside of a transparent support as in US 4,279,945 and US 4,302,523.
• the element typically will have a total thickness (excluding the support) of from 5 to 30 microns. While the order of the color sensitive layers can be varied, they will normally be red-sensitive, green-sensitive and blue-sensitive, in that order on a transparent support, (that is, blue sensitive furthest from the support) and the reverse order on a reflective support being typical.
• the present invention also contemplates the use of photographic elements of the present invention in what are often referred to as single use cameras (or "film with lens” units). These cameras are sold with film preloaded in them and the entire camera is returned to a processor with the exposed film remaining inside the camera. Such cameras may have glass or plastic lenses through which the photographic element is exposed.
• the silver halide emulsions employed in the photographic elements of the present invention may be negative-working, such as surface-sensitive emulsions or unfogged internal latent image forming emulsions, or positive working emulsions of the internal latent image forming type (that are fogged during processing).
• negative-working such as surface-sensitive emulsions or unfogged internal latent image forming emulsions, or positive working emulsions of the internal latent image forming type (that are fogged during processing).
• Suitable emulsions and their preparation as well as methods of chemical and spectral sensitization are described in Sections I through V.
• Color materials and development modifiers are described in Sections V through XX.
• Vehicles which can be used in the photographic elements are described in Section II, and various additives such as brighteners, antifoggants, stabilizers, light absorbing and scattering materials, hardeners, coating aids, plasticizers, lubricants and matting agents are described, for example, in Sections VI through XIII. Manufacturing methods are described in all of the sections, layer arrangements particularly in Section XI, exposure alternatives in Section XVI, and processing methods and agents in Sections XIX and XX.
• a negative image can be formed.
• a positive (or reversal) image can be formed although a negative image is typically first formed.
• the photographic elements of the present invention may also use colored couplers (e.g. to adjust levels of interlayer correction) and masking couplers such as those described in EP 213 490; Japanese Published Application 58-172,647; U.S. Patent 2,983,608; German Application DE 2,706,117C; U.K. Patent 1,530,272; Japanese Application A-113935; U.S. Patent 4,070,191 and German Application DE 2,643,965.
• the masking couplers may be shifted or blocked.
• the photographic elements may also contain materials that accelerate or otherwise modify the processing steps of bleaching or fixing to improve the quality of the image.
• Bleach accelerators described in EP 193 389; EP 301 477; U.S. 4,163,669; U.S. 4,865,956; and U.S. 4,923,784 are particularly useful.
• nucleating agents, development accelerators or their precursors UK Patent 2,097,140; U.K. Patent 2,131,188
• development inhibitors and their precursors U.S. Patent No. 5,460,932; U.S. Patent No. 5,478,711
• electron transfer agents U.S. 4,859,578; U.S.
• antifogging and anti color-mixing agents such as derivatives of hydroquinones, aminophenols, amines, gallic acid; catechol; ascorbic acid; hydrazides; sulfonamidophenols; and non color-forming couplers.
• the elements may also contain filter dye layers comprising colloidal silver sol or yellow and/or magenta filter dyes and/or antihalation dyes (particularly in an undercoat beneath all light sensitive layers or in the side of the support opposite that on which all light sensitive layers are located) either as oil-in-water dispersions, latex dispersions or as solid particle dispersions. Additionally, they may be used with "smearing" couplers (e.g. as described in U.S. 4,366,237; EP 096 570; U.S. 4,420,556; and U.S. 4,543,323.) Also, the couplers may be blocked or coated in protected form as described, for example, in Japanese Application 61/258,249 or U.S. 5,019,492.
• the photographic elements may further contain other image-modifying compounds such as "Development Inhibitor-Releasing” compounds (DIR's).
• DIR's Development Inhibitor-Releasing compounds
• DIR compounds are also disclosed in "Developer-Inhibitor-Releasing (DIR) Couplers for Color Photography," C.R. Barr, J.R. Thirtle and P.W. Vittum in Photographic Science and Engineering, Vol. 13, p. 174 (1969), incorporated herein by reference.
• the concepts of the present invention may be employed to obtain reflection color prints as described in Research Disclosure, November 1979, Item 18716, available from Kenneth Mason Publications, Ltd, Dudley Annex, 12a North Street, Emsworth, Hampshire P0101 7DQ, England, incorporated herein by reference.
• the emulsions and materials to form elements of the present invention may be coated on pH adjusted support as described in U.S. 4,917,994; with epoxy solvents (EP 0 164 961); with additional stabilizers (as described, for example, in U.S. 4,346,165; U.S. 4,540,653 and U.S. 4,906,559); with ballasted chelating agents such as those in U.S.
• the silver halide used in the photographic elements may be silver iodobromide, silver bromide, silver chloride, silver chlorobromide, silver chloroiodobromide, and the like.
• the type of silver halide grains preferably include polymorphic, cubic, and octahedral.
• the grain size of the silver halide may have any distribution known to be useful in photographic compositions, and may be either polydipersed or monodispersed.
• Tabular grain silver halide emulsions may also be used.
• Tabular grains are those with two parallel major faces each clearly larger than any remaining grain face and tabular grain emulsions are those in which the tabular grains account for at least 30 percent, more typically at least 50 percent, preferably >70 percent and optimally >90 percent of total grain projected area.
• the tabular grains can account for substantially all (>97 percent) of total grain projected area.
• the emulsions typically exhibit high tabularity (T), where T (i.e., ECD/t 2 ) > 25 and ECD and t are both measured in micrometers ( ⁇ m).
• the tabular grains can be of any thickness compatible with achieving an aim average aspect ratio and/or average tabularity of the tabular grain emulsion.
• the tabular grains satisfying projected area requirements are those having thicknesses of ⁇ 0.3 ⁇ m, thin ( ⁇ 0.2 ⁇ m) tabular grains being specifically preferred and ultrathin ( ⁇ 0.07 ⁇ m) tabular grains being contemplated for maximum tabular grain performance enhancements.
• thicker tabular grains typically up to 0.5 ⁇ m in thickness, are contemplated.
• High iodide tabular grain emulsions are illustrated by House U.S. Patent 4,490,458, Maskasky U.S. Patent 4,459,353 and Yagi et al EPO 0 410 410.
• Tabular grains formed of silver halide(s) that form a face centered cubic (rock salt type) crystal lattice structure can have either ⁇ 100 ⁇ or ⁇ 111 ⁇ major faces.
• Emulsions containing ⁇ 111 ⁇ major face tabular grains, including those with controlled grain dispersities, halide distributions, twin plane spacing, edge structures and grain dislocations as well as adsorbed ⁇ 111 ⁇ grain face stabilizers, are illustrated in those references cited in Research Disclosure I , Section I.B.(3) (page 503).
• the silver halide grains to be used in the invention may be prepared according to methods known in the art, such as those described in Research Disclosure I and James, The Theory of the Photographic Process . These include methods such as ammoniacal emulsion making, neutral or acidic emulsion making, and others known in the art. These methods generally involve mixing a water soluble silver salt with a water soluble halide salt in the presence of a protective colloid, and controlling the temperature, pAg, pH values, etc, at suitable values during formation of the silver halide by precipitation.
• one or more dopants can be introduced to modify grain properties.
• any of the various conventional dopants disclosed in Research Disclosure , Item 38957, Section I. Emulsion grains and their preparation, sub-section G. Grain modifying conditions and adjustments, paragraphs (3), (4) and (5), can be present in the emulsions of the invention.
• a dopant capable of increasing imaging speed by forming a shallow electron trap (hereinafter also referred to as a SET) as discussed in Research Discolosure Item 36736 published November 1994, here incorporated by reference.
• the SET dopants are effective at any location within the grains. Generally better results are obtained when the SET dopant is incorporated in the exterior 50 percent of the grain, based on silver. An optimum grain region for SET incorporation is that formed by silver ranging from 50 to 85 percent of total silver forming the grains.
• the SET can be introduced all at once or run into the reaction vessel over a period of time while grain precipitation is continuing. Generally SET forming dopants are contemplated to be incorporated in concentrations of at least 1 X 10 -7 mole per silver mole up to their solubility limit, typically up to about 5 X 10 -4 mole per silver mole.
• SET dopants are known to be effective to reduce reciprocity failure.
• the use of iridium hexacoordination complexes or Ir +4 complexes as SET dopants is advantageous.
• Iridium dopants that are ineffective to provide shallow electron traps can also be incorporated into the grains of the silver halide grain emulsions to reduce reciprocity failure.
• the Ir can be present at any location within the grain structure.
• a preferred location within the grain structure for Ir dopants to produce reciprocity improvement is in the region of the grains formed after the first 60 percent and before the final 1 percent (most preferably before the final 3 percent) of total silver forming the grains has been precipitated.
• the dopant can be introduced all at once or run into the reaction vessel over a period of time while grain precipitation is continuing.
• reciprocity improving non-SET Ir dopants are contemplated to be incorporated at their lowest effective concentrations.
• the contrast of the photographic element can be further increased by doping the grains with a hexacoordination complex containing a nitrosyl or thionitrosyl ligand (NZ dopants) as disclosed in McDugle et al U.S. Patent 4,933,272, the disclosure of which is here incorporated by reference.
• NZ dopants a nitrosyl or thionitrosyl ligand
• the contrast increasing dopants can be incorporated in the grain structure at any convenient location. However, if the NZ dopant is present at the surface of the grain, it can reduce the sensitivity of the grains. It is therefore preferred that the NZ dopants be located in the grain so that they are separated from the grain surface by at least 1 percent (most preferably at least 3 percent) of the total silver precipitated in forming the silver iodochloride grains.
• Preferred contrast enhancing concentrations of the NZ dopants range from 1 X 10 -11 to 4 X 10 -8 mole per silver mole, with specifically preferred concentrations being in the range from 10 -10 to 10 -8 mole per silver mole.
• concentration ranges for the various SET, non-SET Ir and NZ dopants have been set out above, it is recognized that specific optimum concentration ranges within these general ranges can be identified for specific applications by routine testing. It is specifically contemplated to employ the SET, non-SET Ir and NZ dopants singly or in combination. For example, grains containing a combination of an SET dopant and a non-SET Ir dopant are specifically contemplated. Similarly SET and NZ dopants can be employed in combination. Also NZ and Ir dopants that are not SET dopants can be employed in combination. Finally, the combination of a non-SET Ir dopant with a SET dopant and an NZ dopant. For this latter three-way combination of dopants it is generally most convenient in terms of precipitation to incorporate the NZ dopant first, followed by the SET dopant, with the non-SET Ir dopant incorporated last.
• Photographic emulsions generally include a vehicle for coating the emulsion as a layer of a photographic element.
• Useful vehicles include both naturally occurring substances such as proteins, protein derivatives, cellulose derivatives (e.g., cellulose esters), gelatin (e.g., alkali-treated gelatin such as cattle bone or hide gelatin, or acid treated gelatin such as pigskin gelatin), deionized gelatin, gelatin derivatives (e.g., acetylated gelatin, phthalated gelatin, and the like), and others as described in Research Disclosure I .
• Also useful as vehicles or vehicle extenders are hydrophilic water-permeable colloids.
• the vehicle can be present in the emulsion in any amount useful in photographic emulsions.
• the emulsion can also include any of the addenda known to be useful in photographic emulsions.
• the silver halide to be used in the invention may be advantageously subjected to chemical sensitization.
• Compounds and techniques useful for chemical sensitization of silver halide are known in the art and described in Research Disclosure I and the references cited therein.
• Compounds useful as chemical sensitizers include, for example, active gelatin, sulfur, selenium, tellurium, gold, platinum, palladium, iridium, osmium, rhenium, phosphorous, or combinations thereof.
• Chemical sensitization is generally carried out at pAg levels of from 5 to 10, pH levels of from 2 to 8, and temperatures of from 30 to 80°C, as described in Research Disclosure I , Section IV (pages 510-511) and the references cited therein.
• the silver halide may be sensitized by sensitizing dyes by any method known in the art, such as described in Research Disclosure I .
• the dye may be added to an emulsion of the silver halide grains and a hydrophilic colloid at any time prior to (e.g., during or after chemical sensitization) or simultaneous with the coating of the emulsion on a photographic element.
• the dyes may, for example, be added as a solution in water or an alcohol.
• the dye/silver halide emulsion may be mixed with a dispersion of color image-forming coupler immediately before coating or in advance of coating (for example, 2 hours).
• Photographic elements of the present invention are preferably imagewise exposed using any of the known techniques, including those described in Research Disclosure I , section XVI. This typically involves exposure to light in the visible region of the spectrum, and typically such exposure is of a live image through a lens, although exposure can also be exposure to a stored image (such as a computer stored image) by means of light emitting devices (such as light emitting diodes, CRT and the like).
• a stored image such as a computer stored image
• Photographic elements comprising the composition of the invention can be processed in any of a number of well-known photographic processes utilizing any of a number of well-known processing compositions, described, for example, in Research Disclosure I , or in T.H. James, editor, The Theory of the Photographic Process , 4th Edition, Macmillan, New York, 1977.
• a negative working element the element is treated with a color developer (that is one which will form the colored image dyes with the color couplers), and then with a oxidizer and a solvent to remove silver and silver halide.
• the element is first treated with a black and white developer (that is, a developer which does not form colored dyes with the coupler compounds) followed by a treatment to fog silver halide (usually chemical fogging or light fogging), followed by treatment with a color developer.
• a black and white developer that is, a developer which does not form colored dyes with the coupler compounds
• a treatment to fog silver halide usually chemical fogging or light fogging
• a color developer usually chemical fogging or light fogging
• Dye images can be formed or amplified by processes which employ in combination with a dye-image-generating reducing agent an inert transition metal-ion complex oxidizing agent, as illustrated by Bissonette U.S. Patents 3,748,138, 3,826,652, 3,862,842 and 3,989,526 and Travis U.S. Patent 3,765,891, and/or a peroxide oxidizing agent as illustrated by Matejec U.S. Patent 3,674,490, Research Disclosure, Vol. 116, December, 1973, Item 11660, and Bissonette Research Disclosure, Vol. 148, August, 1976, Items 14836, 14846 and 14847.
• the photographic elements can be particularly adapted to form dye images by such processes as illustrated by Dunn et al U.S.
• Patent 3,822,129, Bissonette U.S. Patents 3,834,907 and 3,902,905 Bissonette et al U.S. Patent 3,847,619, Mowrey U.S. Patent 3,904,413, Hirai et al U.S. Patent 4,880,725, Iwano U.S. Patent 4,954,425, Marsden et al U.S. Patent 4,983,504, Evans et al U.S. Patent 5,246,822, Twist U.S. Patent No.
• the folloing examples illustrate the use of the dye combinations of the invention.
• This example demonstrates the use of dye combinations of this invention with a cubic AgCI emulsion.
• a pure AgCI emulsion of predominantly cubic morphology was used.
• the median grain size was 0.39 micron cubic edge length (CEL).
• the emulsion was chemically sensitized (finished) by melting the emulsion at 40 degrees C, then adding colloidal aurous sulfide at 0.0177 g per mole of AgCI, and heating the emulsion to 65 degrees C for 55 minutes prior to chilling the emulsion.
• the sensitizing dyes were added by re-melting the emulsion at 40 degrees C, and adding the dyes from methanolic solutions at a concentration of 0.000471 moles per liter to produce a dye-to-silver ratio of 3.8 x 10 -4 moles of dye per silver mole.
• the emulsion was held with stirring for 20 minutes, then chilled with stirring.
• the two dyes comprising a particular combination were tested by adding each of them individually to the emulsion, and also by adding them to the emulsion simultaneously from pre-mixed co-solutions in the percentages 75% Dye 1, 25% Dye 2; 50% Dye 1,50% Dye 2; 25% Dye 1,75% Dye 2.
• the dyed emulsions were coated onto an ESTARTM support using a coating machine equipped with an extrusion device to deliver the melted emulsion onto the support.
• the melt as coated consisted of emulsion, gelatin, water, dye solutions as described above, the surfactant saponin (which is a naturally occurring glycoside), and the hardener 1,1'-(oxybis-(methylenesulfonyl)bis-)ethene (BVSME).
• the total "wet" laydown was 157.2 g/m 2 (14.6 mg/ft 2) .
• the resulting single-layer coatings contained 3229 mg/m 2 of silver, 7319 mg/m 2 of gelatin, 122.6 mg/m 2 of BVSME, and 144.8 mg/m 2 of saponin.
• a spectrum was obtained of the coated material using a scanning spectrophotometer equipped with an integrating sphere.
• the coated materials were exposed with a sensitometer equipped with a tungsten light source which is filtered with a collection of Wratten filters designed to approximate exposure through a color film negative.
• a step tablet was used to provide a D logE curve from which photographic speed at 0.8 density units above Dmin was determined, as is familiar to those skilled in the art.
• the exposed strips were developed in the following process at 20 degrees C.
• This emulsion is predominantly AgCI, so that the structural requirement for the practice of the invention is much more stringent than when the substrate is predominantly AgBr.
• dyes may bear two 5 position substituents, at least one of them must be aromatic, and
• the symmetrical dinapthoxazole chromophore is excluded from the invention because it does not aggregate on the AgCI emulsion.
• inventive pairs of dyes maintain the height of the combined aggregate peak, that they result in a steady progression of peak wavelength between the long and the short dye, and that they preserve photographic speed, and that all three of these features are accomplished to a much greater extent than for the comparative pairs of dyes.
• the nominal halide composition was AgBr 97.4% I 2.6% .
• the median grain size was 0.20 ⁇ m equivalent spherical diameter (esd).
• the emulsion was chemically sensitized by melting the emulsion and applying the chemical sensitizers NaSCN at a level of 44 mg per mole of silver, Na 2 S 2 O 3 .5H2O at a level of 33 mg per mole of silver, and KAuCl 4 at a level of 6.6 mg per silver mole.
• the sensitizing dyes were added by re-melting the emulsion at 40 degrees C, and adding the dyes from methanolic solutions at a concentration of 0.00035 moles per liter to produce a dye-to-silver ratio of 8 x 10 -4 moles of dye per silver mole.
• the emulsion was held with stirring for 20 minutes, then chilled with stirring.
• the two dyes comprising a particular combination were tested by adding each of them individually to the emulsion, and also by adding them to the emulsion simultaneously from pre-mixed co-solutions in the percentages 75% Dye 1, 25% Dye 2; 50% Dye 1,50% Dye 2; 25% Dye 1,75% Dye 2.
• the cubic emulsion melts were coated on a machine equipped with an extrusion device to deliver the melted emulsion as a single layer to ESTARTM support.
• the melts were coated at 10.8 mg/dm 2 silver and 77 mg/dm 2 gelatin, and hardened with 0.08% bis(vinylsulfonyl)methylether (BVSME).
• a spectrum was obtained of the coated material using a scanning spectrophotometer equipped with an integrating sphere.
• the coated materials were exposed with a single-grating transmission sensitometer which produces a separate D log E curve at 10 nm intervals across the visible spectrum.
• the result is a "wedge spectrograph", which is well-known in the art. (See, for example, "Use of Spectral Sensitizing Dyes To Estimate Effective Energy Levels of Silver Halide Substrates", by P. B. Gilman, Jr., in Photographic Science and Engineering, Volume 18, Number 5, September/October 1974.)
• the exposed coatings were processed at 35 degrees C in an Eastman KODAK RP X-OMATTM machine.
• inventive pairs of dyes maintain the height of the combined aggregate peak, that they result in a steady progression of peak wavelength between the long and the short dye, and that they preserve photographic speed, and that all three of these features are accomplished to a much greater extent than for the comparative pairs of dyes.
• the nominal halide composition was AgBr 97.0% I 3.0% .
• the median grain size was 0.30 ⁇ m equivalent spherical diameter (esd).
• the emulsion was chemically sensitized by melting the emulsion and applying the chemical sensitizers NaSCN at a level of 150 mg per mole of silver, Na 2 S 2 O 3 .5H 2 O at a level of 8 mg per mole of silver, and KAuCl 4 at a level of 5 mg per silver mole.
• the cubic emulsion melts were coated on a machine equipped with an extrusion device to deliver the melted emulsion as a single layer to ESTARTM support.
• the melts were coated at 21.5 mg/dm 2 silver and 86 mg/dm 2 gelatin, and hardened with 0.08% bis(vinylsulfonyl)methylether (BVSME).
• the sensitizing dyes were added by re-melting the emulsion at 40 degrees C, and adding the dyes from methanolic solutions at a concentration of 0.00032 moles per liter to produce a dye-to-silver ratio of 4.0 x 10 -4 moles of dye per silver mole.
• the emulsion was held with stirring for 20 minutes, then chilled with stirring.
• the two dyes comprising a particular combination were tested by adding each of them individually to the emulsion, and also by adding them to the emulsion simultaneously from pre-mixed co-solutions in the percentages 75% Dye 1, 25% Dye 2; 50% Dye 1,50% Dye 2; 25% Dye 1,75% Dye 2.
• a spectrum was obtained of the coated material using a scanning spectrophotometer equipped with an integrating sphere.
• the coated materials were exposed with a single-grating transmission sensitometer which produces a separate D log E curve at 10nm intervals across the visible spectrum.
• the result is a "wedge spectrograph", which is well-known in the art. (See, for example, "Use of Spectral Sensitizing Dyes To Estimate Effective Energy Levels of Silver Halide Substrates", by P. B. Gilman, Jr., in Photographic Science and Engineering, Volume 18, Number 5, September/October 1974.)
• the exposed coatings were processed at 35 degrees C in an Eastman KODAK RP X-OMATTM machine.
• inventive pairs of dyes maintain the height of the combined aggregate peak, that they result in a steady progression of peak wavelength between the long and the short dye, and that they preserve photographic speed, and that all three of these features are accomplished to a much greater extent than for the comparative pairs of dyes.
• the emulsion used was a predominantly silver chloride, ruthenium doped, (1.0.0) tabular grain emulsion.
• the average grain diameter was 0.60 microns equivalent circular diameter (ecd).
• the average grain thickness was 0.17 microns.
• the precise halide ratio was 99.404% chloride and 0.596 % iodide.
• the emulsion was doped with 125 ppm ruthenium hexacyanide.
• the emulsion was heated to 60°C, held for 25 min. and then cooled to 39°C. Then 100 mg/Ag mole of 1-(3-acetamidophenyl)-5-mercaptotetrazole was added.
• the emulsion was then coated on triacetate film with the yellow coupler of formula Y-C. The film was then dried.
• the film was exposed to white light at 3000K for a time of 0.004 sec. It was then processed in the ECP-2TM process for 3 min. at 98°F. The spectral absorption of the coated film samples was measured on a spectrophotometer. Results were obtained for the different ratiosof sensitizing dyes. These results are given in Table IV.
• the dye quantities given are the percent ratios of the millimoles of dye per silver mole. As can be seen, the dye peak transitions smoothly from 471 nm to 456 nm as the ratio of dye changes.
• Dye combinations were made from two dyes (Table B) which were blended in the following ratios 75/25, 50/50 and 25/75. Dyes and dye combination at a level of 3.8 x 10 -4 moles/Ag mole, were added to an aurous sulfide sensitized 0.39 ⁇ m(cubic edge length) silver chloride cubic emulsions which had 1.0% bromide present. The emulsions were coated on a polyester support in a Black and White format. The coatings were given a 1/10 second exposure on a wedge spectrographic instrument covering a wavelength range from 350 to 750 nm. The instrument contains a tungsten light source and a step tablet ranging in density from 0 to 3 density steps.
• the invention dye combinations allow the sensitization maximum to be adjusted by varying the ratio of the two dyes.
• the invention dye combinations give less speed loss than the comparison dye combination.
• the emulsion is precipitated by bringing together NaCI and AgNO 3 , in the presence of gelatin, antifoamant, dithio-3,6-octane-1,8-diol, and glutaryldiaminophenyldisulfide to form grains of cubic edge length 0.5 ⁇ m - 0.8 ⁇ m, with an aspect ratio of 1.2 or less.
• the emulsion is then chemically and spectrally sensitized by the addition of orthosuccinamidophenyldisulfide, gold(I) bis(1,4,5-trimethyl- 1,2,4-triazolium-3-thiolate)gold(I) fluoroborate, Dye F2, Dye E1 and sodium thiosulfate followed by a heat cycle.
• the emulsion (check) is precipitated by bringing together NaCI and AgNO3, in the presence of gelatin antifoamant, dithio-3,6-octane-1,8-diol, nitric acid,and Hg to form gains of cubic edge length 0.0 ⁇ m - 0.8 ⁇ m.
• the smulsion is then finished by addition of iridium (K 2 IrCl 6 ), sulfur gold(I)/sulfur compound (AuO 6 S4.2H 2 O 3Na, 1-(3-acetamidophenyl)-5-mercaptotetrazole, and thiourea, followed by a heat cycle, followed by addition of comparative dye COMP-1, 1-(3-acetamidophenyl)-5-mercaptotetrazole, KBr, and gelatin.
• iridium K 2 IrCl 6
• sulfur gold(I)/sulfur compound AuO 6 S4.2H 2 O 3Na
• AlO 6 S4.2H 2 O 3Na 1-(3-acetamidophenyl)-5-mercaptotetrazole
• thiourea sulfur gold(I)/sulfur compound
• Comparative dye COMP-1 1-(3-acetamidophenyl)-5-mercaptotetrazole
• gelatin gelatin
• the dye combination of dye F2 and dye E1 does not crystallize in solution, in the sensitized emulsion. Spectroscopic analysis of the emulsions have shown there to be no free dye. Therefore, no filtering is required of the emulsion prior to storage. Dyes F2 and E1 are fully incorporated into the emulsion.
• the new emulsion provides the same sensitometric performance as the check emulsion
• the new emulsion was evaluated in the multilayer format shown in Table V.
• SC-1 1,4-isododecyl hydroquinone Film samples were given white light exposures and processed in Kodak's ECP-2B process, which is well-known in the trade and is documented in Kodak's H-24 manual. The results are given in Table VI(a).
• Emulsion performance characteristics CHARACTERISTIC CHECK EMULSION INVENTION EMULSION Wasted dye due to crystals 30% none Organic solvents yes none speed 100
• 100 contrast 1.0 1.0 short-term LIK ⁇ 0.01 logE speed change per 1.0 log10(minutes) ⁇ 0.01 logE speed change per 1.0 log10(minutes) raw stock keeping no change 3months/13°C no change 3months/13°C lambda-max 461nm 466nm

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