DE1547793A1 - Direct positive silver halide photographic emulsion - Google Patents

Description

Eastman Kodak Company, 3 ^ 3 State Street, Rochester, New York State, United States of America

Direct positive silver halide photographic emulsion

The invention relates to a direct positive fogged photographic silver halide emulsion a sensitizing dye as an electron acceptor.

Direct positive fogged silver halide photographic emulsions are described, for example, in British Patent 723,019. The direct-positive silver halide emulsions described in British Patent 723 019 contain dyes that serve as electron acceptors. However, it has been shown that the previously available known and for example in the British patent 723 019 described electron

acceptors (electron trappers) are not able to make the direct-positive photographic silver halide emulsions spectrally effective to make them more sensitive.

It has now been found that a certain class of unsymmetrical cyanine dyes which differ from N-substituted Carbazole-3-carboxaldehydes not only derive excellent electron acceptors for direct-positive photographic applications Silver halide emulsions can also be excellently spectrally sensitized capital.

The subject of the invention is a direct positive veiled photographic silver halide emulsion containing a sensitizing dye as an electron acceptor, which thereby is characterized in that it has at least one asymmetrical cyanine dye of the following formula as electron acceptor contains:

■ CH C (* «CH — CH) YY ^ -N

909847 / Ü80fl

where mean:

R is an optionally substituted alkyl or aryl radical, an acyl radical or an alkane or Arylsulfonyl radical;

R. an optionally substituted alkyl radical;

R ₂ and R hydrogen or halogen atoms, alkyl radicals or optionally substituted aryl radicals or carboxyl, sulfo, nitro or cyano radicals

X is an acid anion j

Z to complete a 5- or 6-link heterocyclic ring required non-metallic atoms and

η = 1 or 2.

By adding an unsymmetrical cyanine dye of the formula given to a fogged direct-positive photographic silver halide emulsion, this is sensitized to light in the green to red range of the visible spectrum, i.e. up to wavelengths of about 620 to 680 μm, with maximum sensitivities usually around 5 ¹ IO to 580 mu occur.

BATH ORIGINAL

8Q8847 / Q8Cft

The unsymmetrical cyanine dyes used in the present invention are not only excellent electron acceptors and spectral sensitizing dyes but they are also excellently compatible with color couplers.

According to a particularly advantageous embodiment of the In accordance with the invention, the direct-positive silver halide emulsion of the invention contains, as electron acceptor, a dye of the formula given, in which Z represents the atoms necessary to complete a desensitizing nucleus.

According to a further particularly advantageous embodiment of the invention, the direct-positive silver halide emulsion of the invention contains as electron acceptor a dye of the structural formula given, in which Z represents the atoms required to complete a thiazole, oxazole, selenasole, thiazoline, pyrydin, quinoline or imidaseol ring.

The emulsion can be masked in the usual way be, d. H. chemically or by exposure to light.

90 647/0 # original

The concealment by chemical means can be effected by the customary, known concealment agents.

If the emulsion is fogged by chemical means _f such a combination is to conceal some of the other from a so-called Reduktlonssehleiermlttel and a compound of a metal which is elektropositiv®r than silver.

Suitable reduction methods are, for example, Staimoiftls ·, e «B ₉ Stannoe & lorid, Hyuras in, Schwe-felver ~ viiuliitigen, «ie for example) Thioureadloi ^ d, Plios- ■ heitliiualse, wi · s. B, Ttti * (hydrosyMthyl) phosphonluB · ehlorld, fofm * l & mh ^ a wnd dersltifhen * Hp Metall®, di · '

elektropesl% i9 «r« la Silbwz 'nlnA ₉ , be gSFifiKat »SoId ₀ » Platinum, PalladitM and Iridiuas. B «86nö« re gt-

Metsll «* .ΐΐιώ wt> g» «reddish

(NHJj) ₂ FdGIg unü dergltlohcn · Di «Vervenduiig τοη ■ ihloroaurat is btlspitltvtise in the British Pftientsohrift 723 019.

BAD O «'Q! NAl

909847 / ΟΙβΙ

Btsitst in the given formula R denotes an optionally substituted alkyl radical, this preferably has 1 to 8 carbon atoms and consists, for example, of a methyl, ethyl, propyl, butyl or ootyl radical or a sulfoalkyl radical, e.g. B, a sulfopropyl or sulfobutyl radical, a sulfatoalkyl radical, e.g. B · a sulfatopropyl or sulfatobutylreand, or a carboxyalkyl radical, e.g. a carboxyethyl or carboxybutyl radical. If R has the meaning of an aryl radical, this consists, for example, of an optionally substituted phenyl or naphthyl radical, for example a sulfophenyl, carboxypheal or toly radical. Has R dl · importance of Aeylrestes, has the latter preferably 1 to 10 carbon at of 'on, d · fc ₉ of Aeylrest consists for example of a "Aeetyl-, Froplonyl-, B" tyryl- ο4 · τ benzoyl. The meaning of an alkane or arylsulfonyl radical, it has about 1 to 10 carbon atoms, ie. h · the remainder consists, for example, of a · kethanesulfonyl, ithanesulfenyl, butanesulfonyl or lenzeliulfonyl radical.

R _{1 is} preferably an optionally substituted alkyl radical of 1 to 10 carbon atoms, for example a methyl, ethyl, propyl, isopropyl, butyl, oetyl or

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Decyl radical or, for example, a sulfoalkyl radical, ζ. Β. a sulfopropyl or sulfobutyl radical or a sulfatoalkyl radical, e.g. B. a sulfatopropyl radical or a SuIfatο-butyl radical, or a carboxyalkyl radical, e.g. B. a carboxyethyl or carboxybutyl radical.

If R ₂ and R. are alkyl radicals, these preferably have 1 to Ί carbon atoms, ie the radicals consist of methyl, ethyl, propyl, isopropyl and butyl radicals. If R ₂ and R, have the meaning of aryl radicals, these consist, for example, of optionally substituted phenyl or naphthyl radicals, ie, for example of tolyl, chlorophenyl, methoxyphenyl, St ^ -dichlorophenyl or nitrophenyl radicals «have R ₂ and R ^ the meaning of halogen atoms, these preferably consist of chlorine or bromine atoms

X can be, for example, a chloride, bromide, «iodide, p-toluene sulfonate, thiocyanate, sulfamate, methyl sulfate, Ethyl sulfate or perchlorate anion.

The 5- or 6-membered heterocyclic represented by Z Ring can have 1 or 2 heteroatoms and was, for example, oxygen, sulfur, selenium or nitrogen atoms.

ORIGINAL INSPECTED

900847 / QIQI

In particular, Z can stand for one, for example

Thiazole ring, e.g. B. a thiazole, Jl-methylthiazole, il-phenylthiazole, 5-methylthlazole, 5-phenylthiazole,! », S-dimethylthiazole, 4,5-diphenylthiazole, iJ- (2-thienyl) thiazole -, Benzothiazole,! »- Chlorobenzothiazole, 5-chlorobenzothiazole, 6-chlorobenzothiazole, 7-chlorobenzothiazole, 4-methylbenzothiazole, 5-methylbenzothiazole, 6-methylbenzothiazole, 5-bromobenzothiazole, 6-bromobenzothiazole , 5-phenylbenzothiazole, 6-phenylbenzothiazole, 4-methoxybenzothiazole, 5-methoxybenzothiazole, 6-methoxybenzothiazole, 5-iodobenzothiazole, 6-iodobenzothiazole, ή-ethoxybenzothiazole, srahydrobenzothiazole, 5-ethoxybenzothiazole -Dimethoxybenzothiazole, 5 "6-dioxymethylene benzothiazole, 5-hydroxybenzothiazole, 6-hydroxybenzothiazole, Q-naphthothiazole", 0-naphthothiazole, 5-methoxy-β, 0-naphthothiazole, 5-naphthothiazole, 5-naphoxy-thoxy , 8-methoxy-o-naphthothiazole, 7-methoxy-a-naphthothiazole or a ^ '- MethoXythianaphtheno-7 ^f , 6 ♦, 4,5-thiazole ring; ,

an oxazole ring, e.g. B. a 4-methyloxazole, 5-methyloxazole, il-phenyloxazole, 4,5-diphenyloxazole, Ij-ethyloxazole, 4,5-dimethyloxazole, 5-phenyloxazole, benzoxazole, 5-chlorobenzoxazole, 5-methylbenzoxazole, 5-phenylbenzoxazole, 6-methylbenzoxazole-, 5,6-dimethylbenzoxazole-, 4,6-dimethyl-

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benzoxazole, 5-methoxybenzoxazole, 5-ethoxybenzoxazole, 5-chlorobenzoxazole, 6-methoxybenzoxazole, 5-hydroxybenzoxazole, 6-hydroxybenzoxazole, α-naphthoxazole or one β-naphthoxazole ring;

a selenazole ring, e.g. B. a 4-methylselenazole, Ί-phenylselenazole, benzoselenazole 5-chlorobenzoselenazole, 5-methoxybenzoaelenazole, 5-hydroxybenzoselenazole, Tetrahydrobenzoselenazole, a-naphthoselenazole or a O-naphthoselenazole ring j

a thiazoline ring, e.g. B. a thiazoline or 4-methylthiazole ring;

a pyridine ring, e.g. B. a 2-pyridine, 5-methyl-2-pyridine, 4-pyridine or 3-methyl- ¹ »-pyridine ring;

a quinoline ring, e.g. B. a 2-quinoline, 3-methyl-2-quinoline, 5-ethyl-2-quinoline, 6-chloro-2-quinoline, 8-chloro-2-quinoline, 6-methoxy-2- quinoline-, 8-Xthoxy-2-quinoline-, 8-hydroxy-2-quinoline-, 4-quinoline-, 6-methoxy-4-quinoline- _f 7-methyl-M-quinoline-, ß-chloro-M- quinoline, 1-l-quinoline, B ^^ - Dlhydro-l-i-quinoline or 3-isoquinoline ring j

909847/0) 909

a 3 «3 dialkylindolenin ring, preferably with one Nitro or cyano group, e.g. B. a 3 »3-dimethyl-5- or 6-nitroindolenine or 3,3-dimethyl-5- or 6-cyanolndolenine or

an imidazole ring, e.g. B. an imidazole, 1-alkyliraidazole, l-alkyl-4-phenylimidazole-, l-alkyl-4,5-dimethylimidazole-, Benzimidazole, 1-alkylbenzimidazole, 1-aryl-5,6-dichiorο-benzimidazole, 1-alkyl-a-naphthimidazole, 1-aryl-8-naphthimidazole or 1-alkyl-5-methoxy-a-naphthimidazole ring or

a 1 _t 3-diethylimidazof4,5-b) quinoxaline ring.

Those dyes in which Z represents the _{atoms required to complete an imidazo Oi (} 5-b] quinoxaline length have proven to be particularly advantageous.

In general, those dyes have proven to be particularly advantageous in which Z is the complement of a desenslbilislerenden ring represents the atoms required. A desensitizing ring is used understood such a ring, which, when converted into a symmetrical carbocyanine dye and incorporated in the form of this dye into a gelatin silver chlorobromide emulsion, the silver halide of which is 40 mol% of chloride

909847/0809

and 60 MoI-X consists of bromide by electron trapping or picking up electrons to a minimum of 80 years A reduction in the blue sensitivity of the emulsion leads to it if it contains 0.01 to 0.2 g of dye per mole of silver applied to a support according to the sensitometric method Exposure and development for 3 minutes in a developer of the following composition is developed at room temperature.

Water, about 50 ⁰ C 500 cm ^

N-methyl-p-aminophenol sulfate 2.0 g

Sodium sulfite (dehydrated) 90.0 g

Hydroquinone 8.0 g

Sodium carbonate, conobydrate 52.5 g

Potassium bromide 5 »0 g Make up to the liter with water.

Desensitizing cores which, when converted into a symmetrical carbocyanine dye and tested in the manner described, practically lead to complete desensitization of the test emulsion to blue radiation, ie a greater loss of sensitivity to blue radiation, have proven to be particularly advantageous than about 90 to 955t.

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A direct-positive silver halide emulsion has proven to be particularly advantageous which is characterized in that it uses 1,3-diethyi-2-ß- (9-methyl-3-carbazolyl) vinylimidazo ß », 5-b] quinoxalinium iodide; S-methyl-Z-ß - ^ - methyl-S-carbazolydvinyl-o-nitrobenzothiazolium-p-toluenesulfonate; 5-chloro-3-methyl-2-ß- (g-diethyl-S-carbazolydvinyl-o-nitrobenzothiazolium ptoluenesulfonate; 1,3 »3-triraethyl-2-ß- (9-methyl-3-carbazolyl) vinyl -S-nitro-SH-indolium perchlorate or 3-methyl-2-e- (9-methyl-S-carbazolyDvinyl-o-nitrobenzoxazolium-p-toluenesulfonate).

If the direct-positive photographic silver halide emulsion is chemically fogged by means of a reducing compound and a noble metal compound, the known customary concentrations of the compounds can be used for this purpose. Good results can be obtained for example when using mg of 0.05 to ¹ IO reducing compound per mole of silver halide and 0.5 to 15.0 mg of precious metal compound per mole of silver halide.

Particularly favorable results are obtained when the concentrations of both the reducing compound as well as the noble metal compound is kept as low as possible will.

9098A7 / 0809

More generally counter to as "veiled ¹¹ emulsions understood as those whose silver halide grains produce a density of at least 0.5, when an emulsion on a conventional film support at a thickness of 5Q to 500 mg in the form of per o o9 m (1 square foot ) applied, developed without exposure for 5 minutes at 20 ⁰ C in a developer A of the following composition:

Developer A 2.5 G N-methyl-p-aminophenol sulfate 30.0 G Sodium sulfite (anhydrous) 2.5 G Hydroquinone 10.0 G Sodium metaborate 0.5 G Potassium bromide 1.0 liter Topped up with water

The direct positive silver halide photographic emulsion of the invention may, for example, be one whose silver halide grains are one of a water-insoluble Have silver salt existing core and an outer shell made of a veiled, water-insoluble silver salt, which can be developed into silver without exposure. In the case of such a direct positive silver halide photographic emulsion, the dyes are preferred

909847/0101

-Hl-

incorporated into the outer shell of the silver halide grains. Such silver halide emulsions can be prepared, for example, by methods as described in US patent application Ser. M8 467.

For example, the shell of the silver halide grains of such emulsions can be produced by the precipitation of a light-sensitive, water-insoluble silver salt on the cores, a light-sensitive, water-insoluble silver salt being used for the precipitation, which can be veiled, and the veil can be removed again by a bleaching process. The thickness of the shell should be such that the developer is prevented from accessing the core of the grains during the development process. The silver salt of the shell is sufficiently obscured so that a density of at least 0.5 can be achieved if the grains are in the form of an emulsion, which is applied to a support in a layer thickness of 100 mg silver per 0.09 m ² (1 sq .ft.), developed for 6 minutes at 20 ° C in a developer B of the following composition:

9U3847 / QIQ

Developer B 2.5 G N-methyl-p-aminophenol sulfate 10.0 E. Ascorbic acid 35.0 G Potassium metaborate 1.0 G Potassium bromide 1 liter Topped up with water 9.6 PH value

Such fogging can be effected by chemical sensitization to fog using sensitizing compounds described for chemical sensitization of the core emulsion, high intensity light and the like. While the shell of the nuclei ver ^ _; : is droned ₈ , the kernels themselves do not need to be sensitized to obfuscation *

Reducing sensitizers, precious metal salts, such as gold salts in connection with a reducing sensitizer, sulfur sensitizers, high pH values and low pAg values during precipitation of silver halide grains and the like. Optionally, the shell of the silver halide grains can also be used after an emulsion has been applied to one Bearers are veiled.

9098 ^ 7/0809

bath

Before the shell of water-insoluble silver salt is applied to the Silver salt cores is generated, the core emulsion is first subjected to such a chemical or physical treatment that centers are formed on the cores which favor the precipitation or deposition of photolytic silver, d. H. there are so-called Centers generating latent images generated * This can be done, for example, by chemical sensitization processes, as described in the journal "Science et Industries Photographiques ", Volume XXVIII, January 1957, pages 1-23 and 57-65. Such chemical Sensitizations include, for example, gold or precious metal sensitization, sulfur sensitization, z. B. with a compound with a labile sulfur atom and a so-called reduction sensitization, d. H. one Treatment of the silver halide with a strongly reducing compound that leaves small spots or spots metallic silver can be introduced into the silver halide grain or silver halide crystals.

The direct positive silver halide emulsion of the invention however, simple, i. H. veiled silver halide grains not composed of a core and a shell as they are described, for example, in British patent specification 723 019.

9 0 9 8 4 7 / Q 8 0 8

A type of direct-positive silver halide emulsion for which the cyanine dyes used according to the invention have proven particularly useful is further described, for example, in the US patent application with serial no. Described 533 4Ί8 · Such emulsions are characterized in that the silver halide grains are only so far obscured that a mold made of the grains and coated on a support photographic silver halide emulsion when at a temperature of 2O ⁰ C in a developer of the following six minutes Composition:

Water, 52 ⁰ C 500 cm ³

N-methyl-p-aminophenol sulfate 2.5 g Sodium sulfite (dehydrated) 30.0 g Hydroquinone 2.5 g Sodium Taborate x 10.0 g Potassium bromide 0.5 g Made up to 1.0 liter with water

is developed to a maximum density of at least about 1, has a maximum density which is at least about 30% greater than the maximum density of a comparative sample developed under the same conditions after being in a bleach bath ^{at 20 ° C. for 10 minutes} of the following composition:

909847/0101

Kalumcyanld glacial acetic acid Sodium acetate potassium bromide

50 mg 3.17 cm ³ 11. ¹ Ig g 119.0 mg

Made up to 1.0 liter with water

has been bleached.

The grains of such emulsions lose at least about 25> tons and generally at least about 40 g of their Schleyer when they ^{are bleached for 10 minutes at 20 °} C. in a potassium cyanide bath of the composition described.

Such a loss of fog can easily be illustrated by applying the silver halide grains in the form of a photographic silver halide emulsion to a support to achieve a maximum density of at least 1.0 with a 6 minute development at 20 ^° C. in the developer described last and comparing the density achieved with the density of a same emulsion layer which developed for 6 minutes at 20 ° C in the same developer long after the film was developed at about 20 ⁰ C in the Kaliumcyanidbleichbad the composition given 10 minutes. As already stated, the

909847/0801

Maximum density of the unbleached layer by at least 30j, generally at least 60g greater than the maximum density the bleached layer.

For the preparation of the direct-positive photographic silver halide emulsion according to the invention, the conventionally used for the preparation of photographic silver halide emulsions silver halides used are used, d. H. the silver halide grains of the emulsion may, for example consist of silver bromide, silver iodide, silver chloride, silver chlorobromide, silver bromoiodide and the like.

According to a particularly advantageous embodiment of the In the invention, the silver halide of the grains consists of at least 50 mol-i

It has proven to be useful to turn the emulsion around; he such conditions that the mean particle diameter of the silver halide grains is about 0.01 to 2 microns, preferably up to about 1 micron, and more preferably below 0.5 microns.

According to a particularly advantageous embodiment of the Invention have at least 80% by weight or 80% of the number of the silver halide grains of the emulsion, a regular one, preferably a regular cubic structure. However, the shape of the silver halide grains can also be, for example be octahedron. 9O9847 / Q8Q0

According to a further particularly advantageous embodiment, at least 95% by weight of the veiled silver halide grains have a diameter which does not deviate by more than + - H0% from the mean grain diameter. Those emulsions whose silver halide grains have at least 95 parts by weight of a diameter which does not deviate by more than + - 30> from the mean grain diameter are very particularly advantageous.

The average or mean grain diameter can be determined by known methods, such as for example, are described in the magazine "The Photographic Journal ", Volume LXXIX, 1949, pages 330-338.

Direct positive silver halide emulsions of the type just described, d. H. a simple grain structure advantageously obscured to the extent that they result in a density of at least 0.5 when in shape an emulsion in a layer thickness of 50 to about 500 mg

ρ
Silver per 0.09 m (1 square foot) support area applied to a support without exposure for 5 minutes at a temperature of 20 ° C in the developer of the last specified composition (Kodak DK-50).

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As already stated, there have been direct positives Silver halide emulsions have proven to be particularly advantageous, the silver halide of which is at least 50 mol Silver bromide consists. Those emulsions whose silver halide have proven to be particularly advantageous Silver bromoiodide consists, with the iodide content below 10 MoI-Jt lies

The direct positive silver halide emulsion of the invention can be coated on supports in the usual manner. It has been found to be expedient to apply the emulsion to a carrier in a thickness of about 50 to about 500 mg of silver per 0.09 m ^{2 of} carrier area (1 square foot).

The preparation of the direct positive silver halide emulsion according to the invention can be carried out in a known manner, i. H. the dye can be in the emulsion by customary methods be dispersed. The dye is preferably added to the washed, finished emulsion. as It has been found to be useful, the dye from a solution in a suitable solvent, such as Methanol, xsopropanol, pyridine, water and the like. Or To add mixtures thereof to the emulsion.

909647/0309

For the preparation of the direct positive silver halide emulsion of the invention, the usual ones can also be used known hydrophilic colloids can be used, d. H. for example naturally occurring substances such as B. Gelatine, albumin, agar-agar, gum arabic, alginic acid and the like or hydrophilic synthetic plastics, such as, for example, polyvinyl alcohol, polyvinylpyrrolidone, cellulose ethers, partially hydrolyzed cellulose acetates and the same.

The concentration of the dyes used in the present invention in the direct positive silver halide emulsion is not critical. It has proven to be expedient to use the dyes in concentrations of 50 to 2000 mg, preferably 400 to 800 mg, per mole of silver halide.

The direct positive silver halide emulsion of the invention can be coated on conventional photographic supports are, for example, on supports made of glass or films made of, for example, cellulose acetate, cellulose acetate butyrate, Polyester, e.g. B. polyethylene terephthalate, paper, baryta paper, paper coated with a polyolefin layer, z. B, on a paper coated with a polyethylene layer or a polypropylene layer and the like. If necessary, the carrier can also have been irradiated with electrons in order to ensure that the emulsion adheres to the carrier

to enhance. _A , _{A. 4th}

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The asymmetrical cyanine dyes used according to the invention can be easily prepared by condensation of a carbazole-3-carboxaldehyde, preferably of the following general formula:

CHO

wherein R, R and R- have the meaning already given, with a 5- or 6-bellied heterocyclic quaternary salt of the following general formula:

H ₃ C-CC = CH-CH) _n-1 = NR ₁

in which n, R ₁ , X and Z have the meaning already given in an inert dehydrating medium, such as, for example, acetic anhydride, at elevated temperatures, preferably reflux temperatures of the reaction mixtures. The dyes then separate out when the reaction mixture cools and can easily be removed by one or more recrystallization from suitable solvents, for example alkanols or mixtures of alkanols with a phenol, for example by recrystallization from methanol or mixtures

909847/0800

recrystallize from methanol and cresol *

In the reaction of the two reaction components, one can be used in a stoichiorometric excess will. However, approximately equimolecular amounts of the two reaction components are preferably used.

The carbazole-3-aldehydes represented by the given formula II can be prepared by known processes, for example in the book "The Chemistry of Heterocyclic Compounds with Indole and Carbazole Systems ^w Chapter II, Interscience Publishers, New York 195 ^, by WC Sumpter and FM Miller.

Processes for the preparation of heterocyclic compounds of the formula III are also known.

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

I. Preparation of the dyes Dye No. 1 - X .3-Dläthyl-2-e- (g-

viny! imidazo D ** 5-b3 -quinoxalinium iodide

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CHsCH-C

1 * 05 g (1 mol of ⁴⁾ 9-methylcarbazole-3-carboxaldehyde and 1.85 g (1 mol) l _r 3-diethyl-2-raethylimidazo [j _»f 5-bJ chinoxalinlumjodld In 10 ml of acetic anhydride were 5 minutes heated to reflux temperature. Some precipitate separated out. The mixture was then washed with the aid of a little acetic acid into a beaker and herein sidelined · The precipitated dye was abfiltrlert and washed with ether · After two Umkristalllsation of methanol was added 0.48 g, corresponding to n% of theory of pure dye having a melting point of 270 to 273 ° C (dec.) Obtained.

Dye No. 2 - 3-methyl-2-g- (9-methyl-3-carbazolyl) vinyl-6-n-trobenzothiazole mn-p-toluenesulfonate

pVEoluenesulfonate anlon

Means more than molar equivalents

809847/0101

1.05 g (IMol) 9-methylcarbazole-3-carboxaldehyde and 1.90 g (1 mol) 2,3-dimethyl-6-nitrobenzothiazolium p-toluenesulfonate in 25 ml acetic anhydride were heated to reflux temperature for 5 minutes. The dye separated out. The mixture was then rinsed into a beaker with the help of a little acetic acid and chilled. The precipitated dye was filtered off and washed with ether. After two recrystallization from a cresol / methanol mixture, 1.67 g of dye, corresponding to 59% of theory, were obtained. The melting point of the dye was above 300 ^° C.

Dye No. 3 - 5-chloro-3-methyl-2-g- (9-methylcarbazolyl) vinyl-6-nitrobenzothlazollum p-toluenesulfonate

CH = CH-

p ^ toluenesulfonate anion

1 * 05 g (1 mole) 9-methylcarbazole-carboxaldehyde and 2.08 g (1 mole) of 5-chloro-2,3-dimethyl-6-n-trobenzothiazolium p-toluenesulfonate in 20 ml of acetic anhydride were added for 5 minutes long heated to reflux temperature, with a part of the dye precipitated. The cooled mixture was

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then diluted with ether, whereupon the precipitated dye was filtered off and washed with ether. After two times Recrystallization from a cresol / methanol mixture were carried out 1.40 g of pure dye, corresponding to 46% of theory, with a melting point of 297 ° C (dec.) obtained.

II. Preparation of the direct-positive silver halide demulsions example 1

A gelatin-silver bromoiodide emulsion with 2.5 mol / l iodine and an average grain size of the silver halide grains of about 0.2 microns was prepared by mixing an aqueous solution of potassium bromide and potassium iodide and an aqueous solution of silver nitrate simultaneously with vigorous stirring aqueous gelatin solution within a period of 35 minutes at a temperature; *? _ .., TO ⁰ C were added. The emulsion was then chilled, noodled and washed with the aid of cold water in the usual manner. The emulsion was then fogged. By first adding 0.2 mg of thiourea dioxide per mole of silver halide by heating it to 65 ^° C. for 60 minutes, by further adding 4.0 mg of potassium chloroaurate per mole of silver halide and by continuing to heat it ^{to 65 ° C. for 60 minutes.}

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Part of the emulsion was then 0.176 g of the dye No. 1 added per mole of silver. The resulting emulsion was then coated on a conventional cellulose acetate film support applied in such a way that on a support surface

ρ
0.09 m (1 square foot) 100 mg silver and 100 mg gelatin were used.

A sample of the film was then placed in an Eastman Ib sensitometer using a tungsten light source exposed and then developed in a developer C for 6 minutes at room temperature. The developer C had the following composition:

Developer C

N-methyl-p-aminophenol sulfate 2.0 g

Sodium sulfite (anhydrous) 90.0 g, hydroquinone 8.0 g

Sodium carbonate (monohydrate) 52.5 g Potassium bromide _% 5.0 g Make up to 1.0 liter with water

The results of the sensitometric evaluation are compiled in Table I below.

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SA7793

As can be seen from Table I, the dye leads in the exposed areas to a minimum density of only 0.05. The awareness area extends to to 650 mu, with a sensitization maximum of 575 mu. In the case of the comparative sample, which was prepared in the same way but did not contain a sensitizing dye, an increase in density upon exposure was observed. This comparison shows very clearly the excellent suitability of the dye as an electron acceptor and spectral sensitizing dye.

Purple images of excellent quality were obtained when, in a further experiment, l- (2, l «, 6-trichloro-phenyl) -3» 3 '- (2 ", 4" - dl-t-amylphenoxyacetamido) -benzimldazo-5-pyrazolone was incorporated. In this case the emulsion, after application to a support, was exposed in a sensitometer to tungsten light which was filtered through No. 61 and No. 16 Wratten filters. Subsequently was performed an inverse expansion, as shown in example (a) at column 27, lines 27 et seq. of U.S. Patent 3,046,129 except that the black and white development is omitted. In addition, the color development was shortened to 1 minute, as well as the development until after fixation was carried out in total darkness *

ORIGINAL INSPECTED

909847/08 01

SA7793

Example 2

The procedure described in Example 1 was repeated, but this time Dye No. 2 was used. The results of the sensitometric evaluation are also compiled in Table I below. From the received Results show that the dye leads to a minimum density in the exposed areas of only 0.04 and that further the sensitization range is extended to 630 mu, with the maximum sensitivity at 550 mu ligt. In contrast, in a comparative sample that did not contain any dye, the density on exposure

elevated.

Similar results were obtained when dye no. 3 was used.

Dye
concentration
in g / mol TABLE I. Minimum density Sens,
in exposed max.
Districts mu 575 Sens.
area
must dye
No. 0.176 Density in
unexposed
Districts 0.05 550 up to 650 1 0.241 2.02 0.04 to 630 2 o.fo 1.93 0.08 no defl-to 620
kidney tea
Max. 3 - 2.08 Increase in density at the
exposure without 1.98

909847/0809

ORIGINAL INSPECTED

'- /, 7793

Example 3

To 1.08 kg of a gelatin-silver chloride emulsion prepared from 100 g of silver nitrate, 0.017 g of 3-diethyl-2-3- (9-methyl-3-carbazolyl) vinylimidazo \ j \ , 5-b] -quinoxalinium iodide was added . The emulsion was then applied to a non-glossy paper support and flashed with white light so that a density of 1.2 was achieved when the emulsion layer was developed in a developer of the following composition after dilution with 2 parts of water per part of developer:

N-methyl-p-aminophenol sulfate 3.1 g

Sodium sulfite (anhydrous) M5.0 g

Hydroquinone 12.0 g

Sodium carbonate (anhydrous) 67.5 g

Potassium bromide 1.9 g

Made up to 1.0 liter with water

The light-fogged emulsion layer was then imagewise exposed using light for exposure which was filtered through a No. 15 Wratten filter. A direct positive image of excellent quality was obtained.

ORIGINAL INSPECTED

909847/0809

■ 1 S A 7 7 9 3

Similar results were obtained when dye No. 2 was used instead of 1,3-diethyl-2-β- (9-methyl-3-carbazolyDvinylimidazo [* J, 5-bl -quinoxalinium iodides used became.

example 1

3 »175 kg of a gelatin-silver chloride emulsion, produced from 100 g of silver nitrate, was ^{heated to 40 °} C., whereupon the pH was adjusted to 7.8. 8 cm ^ of a 40% formalin solution were then added, whereupon the emulsion was heated to 40 ° C. for a further 10 minutes. The pH of the emulsion was then adjusted to 6.0, whereupon 1.25 g of 3-methyl-2-β- (9-methyl-3-carbazolyl) vinyl-6-nitrobenzothiazolium p-toluenesulfonate were added. The emulsion was then applied to a normal film base and processed as described in Example 1. Direct positive images of excellent quality were obtained.

Correspondingly favorable results were obtained when dye no. 1 was used instead of 3-methyl-2-β- (9-methyl-3-carbazolyl) viny1-6-nitrobenzothiazolium p-toluenesulfonate was used.

909847/0809

¹ SA7793

Equally favorable results as in Examples 1 to 4 were obtained when the dyes used were:

3-methyl 1-2-0- (ii-methyl-T-nitro-S-carbazolyl) vinyl-5-chlorobenzothiazolium-p-toluenesulfonate;

3-ethyl-2-β- (9-ethyl-3-carbazolyl) vinyl-6-nitrobenzothiazolium-p-toluenesulfonate;

3-butyl-2-β- (9-butyl-3-carbazolyl) vinyl-6-chlorobenzothiazolium perehlorate;

3-methyl-2-β- (9-methyl-3-carbazolyl) vinyl-6-nitrobenzoxazolium p-toluenesulfonate;

3-ethyl-2-ß- (9-ethy1-3-carbazoly1) vinyl-5-chlorobenzoxazoliuinp-toluenesulfonate and

1 »3» 3-trimethyl-2-β- (9-methyl-3-carbazolyl) vinyl-5-nitro-3H-indolium perchlorate.

The direct positive silver halide photographic emulsion The invention can be hardened in the usual way, for example by adding aldehyde hardeners such as formaldehyde or mucochloric acid, by azlrldine hardeners, by derivatives of dioxane, by oxypolysaccharides, such as oxidized starch or oxidized vegetable gums and the same.

ORIGINAL INSPECTED

90984 7/0801

1S47793

The emulsion can also contain the usual additives used in the production of direct-positive photographic emulsions, such as, for example, lubricants, Stabilizers, compounds that increase sensitivity, absorption dyes, plasticizers and the like. Furthermore, the emulsions can be used in addition to the spectral sensitizing dyes used according to the invention contain spectrally sensitizing dyes. Furthermore, as already stated, the emulsions can Have color couplers or they can be developed in developer solutions which contain color couplers or other color-producing compounds. As a color coupler you can the usual in the production of color photographic Color couplers used in emulsion layers, d. H. for example so-called monomeric or polymeric color couplers, e.g. B. pyrazolone color couplers, as well as phenolic and heterocyclic and open-chain color couplers with a reactive methylene group. Such color couplers can be incorporated into the emulsion in a known manner, for example by methods such as those described in U.S. Patents 2,322,027; 2,801,171; 1 055 155 and 1 102 028 and 2 186 849 will.

909817/0809

■ iS /, 7793

Optionally, the direct positive photographic Emulsion of the invention also contain incorporated developer compounds, such as polyhydroxybenzenes, Aminophenols, 3-pyrazol donones, and the like.

ORIGINAL INSPECTED

909847/0809

Claims (1)

ι ι: - 36 - U7793 Claims 1. Direct positive fogged silver halide photographic emulsion with a sensitizing dye as electron acceptor, characterized in that they contains at least one asymmetrical cyanine dye of the following formula as electron acceptor: C (—CH CH) - ■ N R, n-i ι ι where mean: R is an optionally substituted alkyl or aryl radical, an acyl radical or an alkane or Arylsulfonyl radical; R _{1 is} an optionally substituted alkyl radical; R ₂ and R- hydrogen or halogen atoms, alkyl radicals or optionally substituted aryl radicals or carboxyl, sulfo, nitro or cyano radicals; 09847 / Q8QS ORIGINAL INSPECTED ISA7793. X is an acid anion; Z to complete a 5- or 6-link heterocyclic ring required non-metallic atoms and η = 1 or 2, 2. Direct positive silver halide emulsion according to claim 1, characterized in that it contains a dye of the formula given as electron acceptor, wherein Z is the for Completion of a desensible kernel required Represents atoms 3 · Direct-positive silver halide emulsion according to claims 1 and 2, characterized in that it contains a dye of the formula given as electron acceptor, in which Z is the one to complete a thiazole, oxazole, selenazole, thiazoline, pyridine, quinoline or Iraidazolinrlnges represents the required atoms. 1. Direct-positive silver halide emulsion according to claims 1 to 3, characterized in that the silver halide grains are fogged emulsion chemically. 90 9 8 4 7 'SA7793 5. Direct-positive silver halide emulsion according to claims 1 to 3, characterized in that the silver halide grains of the emulsion are fogged by the action of light are. 6. Direct-positive silver halide uMon according to claims to 5, characterized in that, as the electron acceptor, 1,3-diethyl-2-β- (9-methyl-3-carbazolyl) vinylimidazo [il, 5-b] quinoxalinium iodide; 3-methyl-2-β- (9-methyl-3-carbazolyl) vinyl-6-nitrobenzothiazolium-p-toluenesulfonate; 5-chloro-3-methyl-2-ß- (9-methyl-3-carbazplyl) vinyl-6-nitrobenzothiazolium-p-toluenesulfonate; 1,3, 3-trimethyl-2-ß- (9-methyl- 3-carbazolyl) vinyl 5-nitro-3H-indolium perchlorate or 3-methyl-2-0- (9-methyl-3-carbazolyl) vinyl-6-nitrobenzoxazolium-p-toluenesulfonate. 7. Direct positive silver halide ^{emulsion according to claim 1} , characterized in that the silver halide grains are obscured by a reducing fogging agent and a gold compound. 909847/0809 8. Direct positive silver halide emulsion according to claim 7, characterized in that the silver halide grains 0.0005 the emulsion with XSyCSCM. up to 0.06 waste equivalent reducing agent and 0.001 to 0.01 millimoles of a compound of a metal more electropositive than Silver, are veiled. 9 _β direct-positive silver halide emulsion according to claim 8, characterized in that the silver halide grains of the emulsion are fleeced with a compound of a metal which is more electropositive than silver and a reducing fogging agent in a ratio of 1: 3 to 20: 1. 10. Direct-positive silver halide emulsion according to Claims to 9, characterized in that the silver halide grains veiled with thiourea dioxide and potassium chloroaurate. 11. Direct-positive silver halide emulsion according to Claims to 10, characterized in that the silver halide grains are only veiled po far, that one made from the grains and applied to a support g "" _84? , Photographic silver halide emulsion, if stored for minutes at a temperature of 20 ⁰ C in tints developer of the following composition: Water, 52 ° C 500 cm ³ N-methyl-p-aainophenol sulfate 2.5 g Sodium sulfite (dehydrated) 30.0 g Hydroquinone 2.5 g Natrlumet aborat 10.0 g Potassium bromide 0.5 g Filled with water to 1.0 liter tu a maxi bask density at least about developed l of is maximum density tint comprising the-at least TTWA 30% gröÄer 1st than the maximum density of a comparison sample which was developed under the same conditions after 10 Mlnuttn slt at 2O ⁰ C in a Bltiohbad of the following composition: Potassium cyanide 50 mg glacial acetic acid 3, * 7 cm ³ Sodium acetate 11, ^ 9 g Potassium bromide 119.0 mg made up to 1.0 liter with water has been bleached 3 0 9847/08 0 f ^{BAD 0RIGlNAL} 12. Direct-positive silver halide emulsion according to Claims 1 to 11, characterized in that at least 80% by weight * or 80% of the number of silver halide grains one regular, preferably cubic-regular, structure. 13. Direct-positive silver halide emulsion according to Claims 1 to 12, characterized in that at least 95% by weight of the veiled silver halide grains have a diameter not more than about - 40 pounds from the mean Grain diameter deviates. l4. Direct-positive silver halide emulsion according to Claims 1 to 13 »characterized in that the middle particle · silver halide grain diameter 0.01 to 2 microns amounts to. 15 · Direct positive silver halide emulsion according to claims 1 to 14, characterized in that the emulsion contains 50 to 2000 mg of the electron acceptor per mole of silver halide contains. 16 · Direct positive silver halide emulsion according to claims 1 to 15, characterized in that the silver halide of the grains consist of at least 50 mol / l of silver bromide.