DE1547789B - Direct positive fogged silver halide photographic emulsion - Google Patents

Description

R ₆ R ₁

contains, wherein R ₁ , R ₂ , R ₃ , R ₅ , R ₆ , Ar and X have the meaning already given and R _{4 is} a radical of the meaning given _{for R 5.}

3. Direct-positive photographic silver halide emulsion according to Claims 1 and 2, characterized in that R ₂ and R ₃ represent the atoms required to form a fused-on benzene ring.

4. Direct-positive photographic silver halide emulsion according to claims 1 to 3, characterized characterized in that Ar has the meaning of a pyridyl ring.

5. Direct-positive photographic silver halide emulsion according to claims 1 to 4, characterized characterized as containing fogged silver halide grains of which at least 95 percent by weight have a diameter that does not deviate by more than ± 40% from the mean grain diameter.

The invention relates to a direct-positive, veiled, photographic silver halide emulsion containing an indole dimethine cyanine spectral sensitizing dye the formula

-Z.

= L-C

R ₆

■ N

R ₅

_Χ Θ

in which Ar denotes an optionally substituted aryl group or a heterocyclic group with 5 or 6 ring atoms with a heteroatom consisting of a nitrogen, oxygen or sulfur atom, L denotes an optionally substituted methine group, Z denotes the atoms required to complete a hetero nucleus, X denotes an anion, R ₁ an optionally substituted alkyl radical or together with R ₆ an optionally substituted alkylene radical, R ₂ and R ₃ individually hydrogen or halogen atoms or alkyl or alkoxy radicals or together the atoms required to form a fused, 6-membered, aromatic ring, R ₅ an optionally substituted one Alkyl or aryl radical, an allyl, alkenyl, alkynyl, cycloalkyl or dialkylaminoalkyl radical and R _{6 is} a hydrogen or halogen atom or an alkyl or alkoxy radical or together with R ₁ an optionally substituted alkylene radical or together with R ₂ to form of a condensed, 6-member Rigen, aromatic ring required atoms, and optionally contains a color coupler.

It is known e.g. B. from British Patent 970 601, direct-positive, fogged, photographic silver halide emulsions to add dimethine cyanine dyes as sensitizers. These dimethine cyanine dyes have an indole nucleus which is substituted in the 2-position by a phenyl radical. By using such sensitizing dyes, images with clear white image areas can be obtained. A disadvantage of these known dimethine cyanine dyes, however, is that when they are used in direct-positive photographic silver halide emulsions, only emulsions with a relatively low sensitivity are obtained.
The object of the invention is to provide direct-positive,

3 4

A coated silver halide photographic emulsion sensitizing dye represented by the following formula
indicate that is sensitized by a dye

who take advantage of the well-known Dimethincyanin- y *

has dyes without having their disadvantages, I

by having direct-positive, veiled, photographi- 5 R / fi \ ru γή γ ¹ Υ * ΐ "Π

see silver halide emulsions more sensitized. y | j äj] ^ "^""^ θ ^ Ι * .1 V

It was found that the task at hand. κ / \ / * Ν * \ |

can be solved by using direct positive, | | Ar X

veiled, photographic silver halide R ₆ Ri
emulsions indole dimethine cyanine dyes included

that have desensitizing nuclei. wherein R ₁ , R ₂ , R ₃ , R ₅ , R ₆ , Ar and X the already indicated

The invention relates to a direct positive, given meaning and R _{4 is} a radical for R ₅

obscured, photographic silver halide is given the meaning.

sion, which is a spectral sensitizing indole In the formulas I and II, Ar can, for example, a

methine cyanine dye of the formula I 15 given above be phenyl or naphthyl nucleus which is

and optionally a color coupler containing the most diverse substituents, e.g. B. by alkyl radicals

is characterized by, since the emulsion those di- with 1 to 8 carbon atoms, such as methyl, ethyl,

methine merocyanines of the general formula I ent propyl or butyl radicals, or with alkoxy radicals

holds, in which Z has a desensitizing effect of about 1 to 8 carbon atoms, such as methoxy, ether

Nitrobenzthiazole, imidazo [4,5 - b] quinoxaline, oxy, propoxy or butoxy radicals may be substituted

3,3 - Dialkyl - 3H - pyrrolo [2,3 - b] pyridine, nitrobenz can. The aryl group represented by Ar can also

oxazole-, nitrobenzselenazole- or nitro-3,3-dialkyl-, for example, be substituted by halogen atoms,,

indole nucleus completed. such as bromine, chlorine or iodine atoms, or by aryl

Under desensitizing nuclei are residues such as phenyl residues.

to understand those nuclei which, if they _{convert the meaning of halogen to a symmetrical carbocyanine dye in the presence of R 2} and R ₃ atoms, these can preferably be chlorine, after incorporation of the dye into one or bromine atoms. If R ₂ and R _{3 have} the gelatin silver chlorobromide emulsion with 40 molar meanings of alkyl or alkoxy radicals, cent silver chloride and 60 mol percent silver bromide preferably have 1 to 8 carbon atoms and a concentration of 0.01 to 0.2 g of dye per 30 consist, for example, of methyl, ethyl, propyl, mol of silver by capturing or absorbing elec- butyl, methoxy, propoxy and hydroxyethyl radicals. trons to a reduction in blue sensitivity If R _{1 has} the meaning of an alkyl radical, the silver halide emulsion has at least 80% of these, preferably 1 to 8 carbon atoms and, if the emulsion is exposed sensitometrically, consists of, for example, methyl, ethyl and 3 minutes is developed for a long time at 20 ° C in a developer A 35 propyl, butyl or octyl radical or a sulfoalkyl of the following composition: radical, e.g. B. a sulfopropyl or sulfobutyl radical,

or a sulfatoalkyl radical, e.g. B. a sulfatopropyl

Water (at about 50 ° C) 500 cm ³ or sulfatobutyl radical, or a carboxyalkyl radical,

N-methyl-p-aminophenol sulfate .... 2.0 g e.g. B. a carboxyethyl or carboxybutyl radical.

Anhydrous sodium sulfite 90.0 g 40 If R ₄ and R ₅ consist of alkyl radicals, these have

Hydroquinone 8.0 g preferably 1 to 18 carbon atoms and

Sodium carbonate, monohydrate ... 52.5 g are available for. B. from methyl, ethyl, propyl, isopropyl,

Potassium bromide 5.0 g butyl, sec-butyl, hexyl, dodecyl or octadecyl

Water made up to 11 residues. R ₄ and R ₅ can also, for example, from

45 benzyl, / I-phenylethyl or sulfoalkyl radicals

As particularly advantageous desensitizing nuclei, z. B. from sulfopropyl or sulfobutyl radicals, those have been found that after the transfer or from sulfatoalkyl radicals, such as. B. sulfatopropylin a symmetrical carbocyanine dye and after or sulfatobutyl radicals, or from carboxyalkyl radicals, the test of the same on the above z. B. Carboxyäthyl- and Carboxybutylresten, or from way to a practically complete Desensibili- 50 hydroxyalkyl, z. B. Hydroxyäthyl- or Hysierung, ie to a reduction of the sensitive droxypropyl or hydroxybutyl residues. If R _{4 has a} speed of at least about 90, preferably at least, and R _{5 is} alkenyl radicals, about 95% can lead to blue radiation. these, for example, consist of propenyl or the invention achieves that high-temp butenyl radicals. If R ₄ and R ₅ mean sensitive, direct-positive silver halide emulsions for 55 alkynyl radicals, then these can be available, for example, from those in which the dye propargyl radicals used consist. As cycloalkyl radicals, the emulsions are not only spectrally sensitized to, for example, cyclobutyl and cyclohexyl radicals of wavelengths beyond 480 πΐμ, but also mentioned. At the same time, a suitable dialkylaminoalkyl radical is, for example, a dimethylaminoethyl radical, with excellent electron acceptability. Have R ₄ goals. With regard to the achievable hervor- 60 and R ₅ the importance of aryl radicals, these can superior spectral sensitization are composed for example of phenyl, p-tolyl, o-Tolylerfindungsgemäßen direct positive silver halide or 3,4-Dichlorphenylresten .

emulsions also in a particularly advantageous manner R ₆ can have the same meaning as R ₂ .

for the production of multilayer color photographic images If R ₆ together with R ₁ forms an alkylene radical, then

Recording materials. 65 this can optionally be substituted, e.g. B.

1 According to a particularly advantageous embodiment by an alkyl radical, a cycloalkyl radical or a

of the invention contains a direct-positive photographic halogen atom, such as a bromine or chlorine atom, or

phical silver halide emulsion has a spectrally sensitive through a cyano radical. Preferably the

Alkylene radical 2 to 3 carbon atoms and thus consists of a dimethylene or trimethyl radical. X can for example be a chloride, bromide, iodide, p-toluenesulfonate, thiocyanate, sulfamate, methyl sulfate, Ethyl sulfate or perchlorate anion.

Direct-positive photographic silver halide emulsions which contain a sensitizing indole dimethine cyanine dye of the above formula I in which R ₂ and R ₃ or R ₂ and R ₆ represent the atoms required to form a fused-on benzene ring have particularly advantageous properties.

According to a further embodiment of the invention, an indole dimethine cyanine dye is used as the spectral sensitizing dye of the formula I given above, wherein Ar is a pyridyl ring, for example a 2-, 3- or 4-pyridyl ring.

Examples of indole dimethine cyanine dyes useful in the spectral sensitization of the silver halide emulsion of the invention are particularly suitable

No.

dye

1,3-diethyl-l'-methyl-2'-phenylimidazo- [4,5-b] -quinoxalino-3'-indolocarbocyano iodide; II 1,1 ', 3', 3'-tetramethyl-2-phenyl-

3-indolopyrrolo [2,3-b] pyridocarbocyanine iodide;

III 1,1 ', 3,3-tetramethyl-5-nitro-2'-phenyl-

indo-3'-indolocarbocyanine iodide;

IV 3'-ethyl-l-methyl-2-phenyl-6'-nitro-

3-indolothiacarbocyanin iodide;

V S'-Chloro-l ^ '- dimethyW-phenyl-

o'-nitro-S-indolothiacarbocyanine p-toluenesulfonate;

VI 3'-Ethyl-1-methyl-6'-nitro-2- (3-pyridyl> -

3-indolothiacarbocyanine-p-toluenesulfonate-hydro-p-toluenesulfonate;

VII 1,3-diethyl-l'-methyl-2 '- (3-pyridyl) -

imidazo- [4,5-b] -quinoxalino-3'-indolocarbocyanine iodide hydroiodide;

VIII l, 3'-dimethyl-6'-nitro-2-phenyl-

3-benz [g] indolothiacarbocyanine p-toluenesulfonate;

IX! '^' - Diet-l-methyW-phenyl-

3-benz [g] indoloimidazo [4,5-b] quinoxalinocarbocyanine iodide;

X 3'-ethyl-6'-nitro-2-phenyl-l, 7-tri-

methylene-3-indolothiacarbocyanine p-toluenesulfonate;

XI U-diethyl ^ '- phenyl-1'J'-trimethyleneimidazo [4,5-b] quinoxalino-3'-indolocarbocyanin iodide;

XII 1 ', 3', 3'-trimethyl-2-phenyl-l, 7-tri-

methylene-3-indolopyrrolo [2,3-b] pyridocarbocyanine iodide;

XIII 6-chloro-1'-methyl-1,2 ', 3-triphenylimide-

azo [4,5-b] quinoxalino-3'-indolocarbocyanine ^ p -toluenesulfonate.

The super halide direct positive photographic emulsions of the invention may be obscured in a known manner, for example by Einwir

35

40

45

55

60 light or so-called chemical concealment agents. Reducing compounds and compounds of metals which are electropositive than silver, e.g. B. Compounds of gold, rhodium, platinum, palladium and iridium.

Examples of typical reducing compounds suitable for masking are the stannous salts, e.g. B. tin (II) chloride, hydrazine, formaldehyde, sulfur compounds, e.g. B. thiourea dioxide, and phosphonium salt, z. B. Tetra (hydroxymethyl) phosphonium chloride. Thiourea dioxides have proven to be particularly advantageous. Examples of typical noble metal compounds which are suitable for concealment are potassium chloroaurate, gold (III) chloride and (NH ₄ I _{2 PdCl 6,} described in British patent specification 723 019. The use of these has been found to be particularly advantageous Noble metal compounds have been shown, which are in the form of their water-soluble salts.

The concentration of the compounds used for obfuscation can vary widely. It has proven to be expedient to add about 0.05 to 40 mg of reducing compound per mole of silver halide and to use 0.5 to 15.0 mg of the noble metal compound. Particularly beneficial results will be then obtained when particularly low concentrations of both reducing compound and be used on noble metal compound.

The dyes can also be added in various concentrations. As functional it has been found to add 50 to 2000 mg, preferably 400 to 800 mg, of dye per mole of silver halide use.

The silver halide grains of the direct positive silver halide photographic emulsion of the invention can consist of the commonly known silver halides used for the production of direct-positive photographic Silver halide emulsions are used; d. that is, the grains can, for example, be made of silver bromide, Silver iodide, silver chloride, silver chlorobromide, silver bromoiodide and silver chlorobromoiodide exist.

"Veiled" emulsions are referred to here as those which provide a density of at least 0.5 when applied in a thickness of 50 to 500 mg of silver per 0.09 m ^{2 of} support surface to a conventional photographic support without being exposed, Developed for 5 minutes at 20 ° C in a developer with the following composition:

Developer B.

N-methyl-p-aminophenol sulfate 2.5 g

Sodium sulfite (anhydrous) 30.0 g

Hydroquinone 2.5 g

Sodium metaborate 10.0 g

Potassium bromide 0.5 g

Made up to 1.0 1 with water

The direct positive silver halide photographic emulsions of the invention can, among others consist of emulsions in which the silver halide grains have a water-insoluble silver salt nucleus and an outer shell, the latter consisting of a veiled, water-insoluble Silver salt is made up of which can be developed into silver without exposure. In the case of such emulsions

the dyes are preferably on the outer shell.

The shell of such grains can be produced, for example, by precipitating a photosensitive, water-insoluble, concealable silver salt onto the silver halide cores, it being possible for the haze to be removed by a bleaching process. The shell should be sufficiently strong so that the developer used in developing the emulsion is prevented from penetrating the core of the silver halide cores. The surface of the silver salt shell is veiled so that it can be developed into metallic silver with conventional surface developers. The silver salt of the shell is expediently obscured to such an extent that a density of at least about 0.5 is achieved when the emulsion is applied at a strength of 100 mg per 0.09 m ² to a normal layer support for 6 minutes at 20 ° C is developed in a developer C of the composition given below:

N-methyl-p-aminophenyl sulfate ..: .. 2.5 g

Ascorbic acid 10.0 g

Potassium metaborate 35.0 g

Potassium bromide 1.0 g

Made up to 1.0 1 with water

pH 9.6

Such concealment can be achieved by chemical sensitization to haze with sensitizers that are suitable for chemical sensitization of the core emulsion, or by exposure to high intensity light. While thus the nuclei of the silver halide grains need not be sensitized to concealment, the envelopes are concealed. Disguising with a reducing sensitizer, a Precious metal salt, e.g. B. a gold salt, and a reducing sensitizer or a sulfur sensitizer, while maintaining high pH values and low pAg values during the precipitation of silver halide. Optionally, the shell of the grains can also be applied after the emulsion has been applied a layer support can be obscured.

Before the casings are applied to the silver salt cores, the cores are first applied chemically or physically in a known manner, centers which cause the precipitation of accelerate photolytic silver. Chemical sensitization processes, for example, can be used for this purpose as they are from the journal "Science et Industries Photographiques", Volume XXVIII, January 1957, pp. 1 to 23 and pp. 57 to 65 are known.

Such direct-positive photographic silver halide emulsions have also proven to be particularly advantageous Proven according to the invention, the silver halide grains are only so veiled that one Photographic preparations made from the silver halide grains and coated on a support Silver halide emulsion when left in developer B for 6 minutes at a temperature of 20 ° C developed to a maximum density of at least about 1 has a maximum density that is at least about 30% greater than the maximum density of a comparative sample that is equal to Conditions developed after being in a bleach bath for 10 minutes at 20 ° C as follows composition

Potassium Cyanide 50 mg

Glacial acetic acid 3.47 cm ³

Sodium acetate 11.49 g

Potassium bromide 119 mg

Made up to 1.01 with water

has been bleached.

Are such emulsions 10 minutes at 20 ° C in a potassium cyanide bath of the specified composition bleached, there is a loss of fog of at least about 25 percent, generally at least 40% a. Such a loss of fog can easily be illustrated if an appropriate emulsion applied to a layer support and the emulsion with 6 minutes of development at 20 ° C in a developer B is developed to a maximum density of at least 1.0. If you compare the Density of such a layer with the density of an identical layer that has been applied for 6 minutes at 20 ° C in the same developer was developed after it had previously been in one for about 10 minutes at 20 ° C Potassium cyanide bleach bath of the specified composition was bleached, it is found that the maximum The density of the unbleached layer is at least 30% greater, generally at least 60% greater than the maximum density of the bleached layer.

Such direct-positive photographic silver halide emulsions have proven to be particularly advantageous in which the silver halide grains have an average grain size of less than about 1 micron, preferably less than about 0.5 micron. The silver halide grains can be a have the usual known crystal forms, d. that is, the grains can be, for example, cubic or octahedral being. Such direct-positive photographic silver halide emulsions have proven to be particularly advantageous proven in which at least 80 percent by weight or 80% by number of the silver halide grains have a regular structure. Preferably at least 80 percent by weight or 80% by number of the silver halide grains. a regular cubic structure.

It has also proven to be particularly advantageous if the silver halide grains of the emulsion have the same grain diameter as possible, ie if the silver halide grains are as large as possible. According to a further preferred embodiment of the invention, the direct-positive silver halide emulsion contains fogged silver halide grains, of which at least 95 percent by weight have a diameter which does not deviate by more than ± 40% from the mean grain diameter. The mean grain diameter preferably deviates from the mean grain diameter by no more than ± 30%.

The average grain diameter can be calculated, for example, from the method from »The Photographic Journal ", Vol. LXXIX, 1949, pp. 330 to 338, known methods can be determined.

Such direct-positive photographic silver halide emulsions have also proven to be particularly advantageous proven, the halide of which consists of at least 50 mol percent of bromide, with particular useful emulsions are silver bromoiodide emulsions, especially those that are less than about 10 mole percent Contain iodide.

The direct positive photographic silver halo

209 537/452

Genide emulsions of the invention can be applied to conventional layer supports in the conventional manner. The emulsions are preferably applied to the support in a layer thickness such that 50 to 500 mg of silver are present ^{on a support area of 0.09 m 2.} The dimethine cyanine dyes are preferably added to the washed, finished silver halide emulsion, for example in the form of solutions in suitable solvents, and thoroughly dispersed therein.

If the direct-positive photographic emulsions of the invention contain color couplers, these are among them Such compounds are meant, those with the oxidation products of primary, aromatic Amines couple existing developer compounds with the formation of dyes and in photographic Do not diffuse silver halide emulsions.

In the following, the preparation of some dyes used according to the invention will first be described in more detail will.

Dye No. VI S'-Ethyl-1-methyl-o-nitro ^ -iS-pyridyO-S-indolothiacarbocyanine-p-toluenesulfonate-hydro-p-toluenesulfonate

CH, -N

CH ₃ · C ₆ H ₄ SO ₃ H · N

NO,

CH = CH-C

QH ₅
CH ₃ C ₆ H ₄ SO ₃ Q

A mixture of 1.12 g of l-methyl-2- (3-pyridyl) indole-3-carboxaldehyde, 1.98 g (1 mole) of 3-ethyl-2-methyl-6-nitrobenzothiazolium - ρ - toluenesulphonate and 0.95 g (1 mol) of p-toluenesulphonic acid in 10 ml of acetic acid was heated to reflux for 5 minutes and then the mixture was cooled. The Reaction product was precipitated by slowly adding excess ether with stirring. The precipitated product was filtered off and dried. After two recrystallizations Ethanol, 2.45 g of dye, according to theory, were obtained.

Dye No. VII

quinoxalino ^ '- indolocarbocyanine iodide hydroiodide

C ₂ H ₅

CH, -N

THERE

CH = CH-C

ever

0.32 g, corresponding to 9% of theory! The melting point of the dye was 223 ^° C. (dec).

Dye No. VIII

1,3'-Dimethyl-6'-nitro-2-phenyl-3-benz [g] indolothiacarbocyanine p-toluenesulfonate

CH, -N

40

NO ₁

CH = CH-C

CH ₃

CH ₃ C ₆ H ₄ SO ₃ ⁵

45

1.12g of 1 - methyl - 2 - (3 - pyridyl) indole - 3 - carboxaldehyde and 1.39 g (1 mole) 1,3-diethyl-2-methylimidazo [4,5-b] -quinoxalinium chloride in 10 ml acetic anhydride were refluxed for 5 minutes. Then the mixture was cooled, whereupon 1 ml of concentrated hydrochloric acid was added. The mixture was then cooled whereupon the reaction product is precipitated in the form of an oil by adding excess ether would. The ether was decanted off, whereupon the residue was dissolved in 50 ml of hot 50% ethanol would. Then 2 g of potassium iodide were added. The dye which separated out on cooling was filtered off and recrystallized from methanol. The yield of purified dye was 1.43 g of 1 - methyl - 2 - phenylbenz [g] indole - 3 - carboxaldehyde and 1.90 g of 2,3 - dimethyl - 6 - nitrobenzothiazolium - ρ - toluenesulfonate in 20 ml of acetic anhydride were refluxed for 5 minutes with constant stirring. After Cooling, the mixture was diluted by adding ether, whereupon the precipitated dye was filtered off and washed with ether. After two recrystallizations from methyl alcohol, the value was the yield of purified dye 1.22 g, corresponding to 38% of theory. The melting point of the The dye was 287 to 289 ° C (dec).

Dye No. IX

l ', 3'-Diethyl-1-methyl-2-phenyl-3-benz [g] -indoloimidazof ^ S-bJ-quinoxalinocarbocyanine iodide

CH, -N

CH = CH

1.43 g 1 - methyl - 2 - phenylbenz [g] indole - 3 - carboxaldehyde, 1.84 g 1,3 - diethyl - 2 - methylimidazo- [4,5-b] quinoxalinium iodide in 20 ml acetic anhydride were refluxed for 5 minutes with constant stirring. The mixture was allowed to cool and diluted with ether. The precipitated dye was filtered off. To twice recrystallization from methanol, the yield of purified dye was 0.48 g, correspondingly 15% of theory. The dye had a melting point of 293 to 294 ° C (dec).

Dye No. X

3'-Ethy 1-6 '-nitro-2-phenyl-1,7-trimethylene-S-indolothiacarbocyanine-p-toluenesulfonate

1.31 g of 2-phenyl-1,7-trimethylene indole-3-carboxaldehyde and 1.98 g of 3-ethyl-2-methyl-6-nitrobenzothiazolium - ρ - toluenesulfonate in 10 ml of acetic acid were refluxed for 5 minutes. The mixture was then cooled, whereupon a solid precipitate parted. The mixture was then diluted with ether. The unusual one Precipitate was filtered off and washed with ether. After two recrystallizations Methanol, the yield of purified dye was 1.54 g, corresponding to 48% of theory. the The compound's melting point was 254-255 ° C (dec).

Dye No. XI

Dye No. XII

l '^' ^ '- TrimethyW-phenyl-lJ-trimethylene-

3-indolopyrrolo [2,3-b] pyridocarbocyanine iodide

the formula

H, C

CH = CH

30th

35

1,3-Diethyl-2'-phenyl-1 'J'-trimethyleneimidazo ^ S-bjquinoxalino-S'-indole carbocyanin iodide 1.31 g of 2-phenyl-1,7-trimethylene indole-3-carboxaldehyde and 1.84 g of 1.3 - Diethyl - 2 - methylimidazo- [4,5-b] quinoxalinium iodide in 10 ml acetic anhydride were heated to reflux temperature for 5 minutes. The mixture was then cooled and diluted with ether. The deposited precipitate was filtered off and washed with ether. After two recrystallizations from methanol, the yield of purified dye was 0.33 g, corresponding to 11% of theory. The melting point of the dye was 230 to 231 ⁰ C (dec).

parted in the form of an oil. The essential layer was then decanted off, whereupon the oil in a small amount Part of ethanol was dissolved. Thereupon, 1.0 g of sodium iodide was dissolved in a small amount Water, added. The mixture was then quenched and the precipitated dye was filtered off and washed with ethanol. After recrystallization from methanol once, the yield was of purified dye 0.35 g, corresponding to 21% of theory. The melting point of the dye was at 283 to 284 ° C (dec).

In a corresponding manner, other dyes can be produced instead of a trimethylene bridge contain a dimethylene bridge.

In the case of dyes of type VII, the trimethylene group can advantageously be substituted, for example by an alkyl radical on the 1-, 2- or 3-carbon atom (calculated from the nitrogen atom of the indole nucleus). The 2-carbon atom can advantageously also be replaced by halogen atoms or Be substituted by cyano groups.

The following examples are intended to illustrate the invention in more detail.

The dyes also tested in the following examples for comparison purposes, which are were not known dyes used according to the invention, consisted of:

A. 3 '-Ethyl-1 -methyl ^ -phenyW-indolo-oxacarbocyanine perchlorate,

B. S'-EthyW-p-methoxy-phenyl-l-methyl-S-indolooxacarbocyanine iodide,

C. 3'-Ethyl-1-methyl-2-phenyl-3-indolothiacarbocyanine perchlorate,

D. 3 '-Ethyl-1 -methyl ^ -phenyl-S-indoloselenacarbocyanine iodide,

E. S'-Ethyl ^ -p-methoxy-phenyl-l-methyW-indoloselenacarbocyaninjodid,

F. 1,3 '-Dimethyl - ^ - phenyW ^' - benzo'-S-indolothiacarbocyanine-p-toluenesulfonate.

45

55

60

0.8 g of 2-phenyl-1,7-trimethyleneindole-3-carboxaldehyde, 0.54 g of U ^ trimethyl ^ methylene ^ dihydropyrrolo- [2,3-b] pyridine and 0.59 g (1 mole) of p-toluenesulfonic acid, monohydrate in 10 ml of acetic anhydride were refluxed for 1 minute. The mixture was then cooled and with Ether dilutes, whereupon the reaction product

example 1

First of all, a gelatin silver bromide iodide emulsion obscured by a reducing compound and a gold compound, in which the halide was 2.5 mole percent iodide and its silver halide grains had an average grain size of about 0.2 microns, made as follows:

An aqueous solution of potassium bromide and potassium iodide was combined with an aqueous Solution of silver nitrate with vigorous stirring to an aqueous gelatin solution at a temperature of 70 ° C added within 35 minutes. The emulsion was then quenched in a known manner, noodles and washed in the usual way with cold water. Then the emulsion obscured by first adding 0.4 mg of thiourea dioxide per mole of silver, the emulsion Heated to 65 ° C. for 60 minutes, 2.0 mg of potassium chloroaurate per mole of silver added and the emulsion was heated again to 65 ° C for 60 minutes. The fogged emulsion obtained was then in several. Shares, whereupon 0.87 millimoles of the shares listed in the following table

led dyes per mole of silver halide were added. The various emulsion fractions were then applied to cellulose acetate film supports in the usual manner in such a way that 100 mg of silver and 400 mg of gelatin were ^{applied to a support area of 0.09 m 2.} A second emulsion was prepared in the same way, but only fogging with thiourea dioxide. Fogging was carried out by adding 40 mg of thiourea dioxide per mole of silver halide to the emulsion and heating the emulsion at 65 ° C. for 60 minutes. The fogged emulsion was divided into several portions, and 0.87 millimoles of dye per mole of silver halide were added to the portions. The emulsions were then also so on cellulose acetate film support

applied so that 100 mg of silver and 400 mg of gelatin were accounted for on a carrier area of 0.09 m ^2.

Samples of the resulting recording materials were then placed in an Eastman sensitometer Ib exposed using a tungsten lamp. The films were made with unfiltered light exposed as well as with blue light through Wratten filters No. 35 and 38 A and further with minus blue light through a No. 16 Wratten filter. The exposed specimens were then developed for 6 minutes in a developer A of the specified composition.

The test specimens were then fixed, washed and dried in a known manner. There were get the following results:

Table I.
A. Concealment with thiourea dioxide and potassium chloroaurate

attempt dye 3 Relative blue Relative minus blue Vcrnaiinis of v / id / d No. No. ^A max sensitivity (B) sensitivity (MB) 0.41 1 A. 490 54 22nd 0.485 2 B. 440 33 _BC 16 2.86 3 C. 530 126 360 3.93 4th D. 535 145 570 3.49 5 E. 550 132 460 1.24 6th F. 440 63 78 13.1 7 *) I. 550 210 2760 3.96 8th*) III 530 225 890 13.9 9 *) IV 560 185 2570 14.4 10 *) V 575 210 3020 17.7 11 *) VI 570 205 3630

*) According to the invention.

B. Concealment with thiourea dioxide

Dye no. Relative attempt
No. sensitivity
opposite to A. white light 12th B. 1.15 13th C. 2.2 14th D. 6.8 15th E. 2.6 16 F. 2.0 17th I. 0.5 18 *) III 21.0 19 *) IV 15.0 20 *) V 19.0 21 *) VI 17.0 22 *) 30.0.

is applied (experiments 7 to 11 and 18 to 22), compared to emulsions to which known dyes are added (Trials 1 to 6 and 12 to 17).

As has already been explained, nuclei with a desensitizing effect are understood to be those which, if they are converted to a symmetrical carbocyanine dye, with at least an 80% loss the relative blue sensitivity of a test emulsion.

The following Example 2 illustrates the results of experiments with various dyes were carried out, during their production desensitizing cores in symmetrical carbocyanine dyes were convicted.

*) According to the invention.

From the results compiled in Table I- results in the unexpectedly high increase in sensitivity when using the invention used dimethine cyanine ver

Example 2

Dyes No. VI through IX were made in various proportions with thiourea dioxide and potassium chloroaurate fogged emulsion, prepared as described in Example 1, added, whereupon the emulsions, as described in Example 1, applied to cellulose acetate and for 6 minutes in one Developer A. The following results were obtained:

15th . 1,547,789 density D _m ; "in exposed 16 Awareness raising Conc. in unexposed
Districts range in πΐμ g / mole Table Il 1.84 Awareness raising to 610 dye 0.258 1.81 maximum in ηΐμ up to 600 No. 0.244 1.99 560 up to 600 VI 0.243 1.96 550 up to 590 VII 0.20 Districts 565 VIII 0.07 535 IX 0.04 0.08 0.05

Comparative experiment 2.05.

Increase in density upon exposure.

Surprisingly, it has been shown that the invention used dimethine cyanine dyes in which the indole nucleus consists either of a benz [g] indole nucleus or a pyridyl ring substituted indole nucleus, emulsions can advantageously be added which Color coupler included. This result is surprising because known indole dimethine cyanine dyes hitherto it has not been possible to add any emulsions containing color couplers.

Example 3

The dye IX was added to an emulsion which was prepared as described in Example 1, however, this emulsion contained a color coupler. For comparison purposes, corresponding Emulsions made using known dyes. The emulsions were then converted into the usual: Way applied to cellulose acetate film support, where exposed to the test specimens obtained and 6 minutes have been developed for a long time. The following results were obtained:

Table III

dye Conc. Dispersion density D _mi "in exposed Awareness raising Awareness raising in unexposed
Districts Districts maximum Area No. g / mole Ωΐμ Πΐμ A. 0.187 B. 1.66 0.05 630 to 685 A. 0.187 1.66 rise the density exposure C. 0.675 D. 1.56 0.06 I 550 C. 0.675 1.57 rise the density to 605 IX 0.735 D. 1.38 0.06 exposure IX 0.735 1.52 0.38 550 535 to 610 to 580

In the table means

A l, r-dimethyl-2,2'-diphenyl-3,3'-indolocarbocyanine bromide,

B, a dispersion of a phenolic cyan coupler of that described in U.S. Patent 2,474,293 Type in di-n-butyl phthalate,

C l, 3-diethyl-r-methyl-2'-phenylimidazo [4,5-b] quinoxolino-3-indolocarbocyanine iodide,

D a dispersion of a pyrazolone magenta coupler of that described in U.S. Patent 2,600,788 Type in tri-o-cresyl phosphate.

When the dyes VI and VII were used in emulsions containing color couplers, the results were equally favorable Results as obtained using dye IX.

209 537 //

Claims (2)

Patent claims: 1. Direct positive fogged silver halide photographic emulsion containing a spectral sensitizing agent Indole dimethine cyanine dye of the formula L-C j (I) N '' 'X® R ₅ in which Ar denotes an optionally substituted aryl group or a heterocyclic group with 5 or 6 ring atoms with a heteroatom consisting of a nitrogen, oxygen or sulfur atom, L an optionally substituted methine group, Z the atoms required to complete a hetero nucleus, X® an anion, R _{1 is} an optionally substituted alkyl radical or together with R _{6 is} an optionally substituted alkylene radical, R ₂ and R _{3 are} individually hydrogen or halogen atoms or alkyl or alkoxy radicals or together are the atoms required to form a fused, 6-membered, aromatic ring, R _{5 is} an optionally substituted alkyl or aryl radical, an allyl, alkenyl, alkynyl, cycloalkyl or dialkylaminoalkyl radical and R _{6 is} a hydrogen or halogen atom or an alkyl or alkoxy radical or together with R ₁ an optionally substituted alkylene radical or together with R ₂ the for Formation of a condensed, 6glie Drigen, aromatic ring required atoms, and optionally contains a color coupler, characterized in that the emulsion contains those dimethine merocyanines of the general formula I in which Z is a desensitizing nitrobenzthiazole, imidazo [4,5-b] -quinoxaline, 3, 3 - dialkyl - 3 H - pyrrolo [2,3 - b] - pyridine, nitrobenzoxazole, nitrobenzselenazole or nitro - 3,3 - dialkyl - indolenine nucleus. 2. Direct positive photographic silver halide emulsion according to claim 1, characterized in that that they use a spectral sensitizing dye of the following formula