DE1547788A1 - Direct positive silver halide photographic emulsion - Google Patents

Description

Eastman Kodak Company, 3 ¹ J 3 State Street, Rochester, New York State, United States of America

Direct positive silver halide photographic emulsion (Pall A) (R. A. Litzerman)

The invention relates to direct positive photographic Silver halide emulsion containing silver halide grains which are fogged and at least halide thereof 50 mole? consists of chloride and which also contain an electron or halogen acceptor.

Direct positive photographic silver halide emulsions with Silver halide grains which are fogged for the production of direct positive photographic images are known. Such Emulsions are described, for example, in British Patent 723,019. The previously known direct positive photographic silver halide emulsions with fogged silver halide grains for the production of direct-positive images

90.9847 / 080t

have the disadvantage that they have a low sensitivity and are therefore unsuitable for many uses. Direct-positive photographic ones have proven particularly suitable Silver halide emulsions with fogged silver halide grains, the halide of which is at least 50 mol-Si from chloride consists. Such direct-positive emulsions can be developed quickly and processed into images.

The invention was based on the object of improving the known direct-positive photographic silver halide emulsions with silver halide grains which are fogged and whose halide consists of at least 50 mol% of chloride and which contain an electron or halogen acceptor in such a way that they are improved Emulsions have improved sensitivity and produce images whose unexposed areas have a high density.

The invention was based on the knowledge that the task set by means of a direct-positive photographic Silver halide emulsion of the type described can be dissolved when the silver halide grains are on its surface Have electron acceptors or halogen acceptors of certain properties and, if further, the silver halide grains have a bromide precipitate on their surface and also optionally an iodide leather precipitate.

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Accordingly, the invention relates to a direct positive silver halide photographic emulsion Silver halide grains that are veiled and their Halide consists of at least 50 mol-} chloride and

and / a content of an electron or halogen acceptor, which is characterized in that the silver halide grains have on their surface;

(a) An electron acceptor with anodic and cathodic

polarographic potentials, which adds one

and/
positive sum or a halogen acceptor with an anodic polarographic potential of less than 0.85 and a cathodic polarographic potential that is more negative than -1.0 and

(b) a bromide precipitate and, if applicable, also an iodide precipitate.

The silver halide grains of direct positive photographic Silver halide emulsions of the invention thus have a bromide and optionally an iodide on their surface regardless of whether the silver halide grains themselves are halide, bromide or iodide, be it in form of silver bromide or silver iodide or mixed silver halides, such as silver bromoiodide or silver chloroiodide.

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The knowledge underlying the invention that the deposition of a bromide precipitate on the Silver halide grains of the silver halide emulsion increase the sensitivity of the grains and thus of the emulsion could not have been foreseen. Furthermore, it was not foreseeable that particularly favorable maximum density values would result would then be achieved if in addition to the deposition of bromide on the silver halide grains Iodide is deposited.

The deposition or precipitation of bromides and Iodides on the surface of the silver halide grains can easily be carried out in such a way that the Silver halide grains brought into contact with water-soluble bromides and optionally water-soluble iodides will.

For the precipitation of the bromide and iodide low damage In the case of silver halide grains, all commonly known water-soluble bromides and iodides (salts) have been found. Examples include ammonium and alkali bromides and iodides, such as ammonium, potassium, Sodium and lithium bromide or iodide and alkaline earth bromides and iodides, such as strontium bromide and iodide as well as, for example, furthermore cadmium bromide and iodide.

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For making a direct positive photographic The silver halide emulsion of the present invention can be the water-soluble salts of the emulsion of the silver halide grains Various concentrations can be added in the oven. An increase in the sensitivity of the silver halide grains occurs even with the separation of very small amounts of a bromide precipitate and an improvement the maximum density values even with the deposition of small iodide precipitates.

It has been found to be expedient to add about 0.01 to about 0.2 moles of bromide salt per mole of silver when preparing the emulsion. It has proven to be particularly advantageous to add about 0.04 to about 0.09 moles to the emulsions For example, it is possible to add about 1 to 20 g, preferably 4 to 9 g of potassium bromide per mole of silver to the emulsion about 0.01 to about 0.2 moles of bromide per mole of silver and preferably about 0.04 to about 0 _t 09 moles per mole of silver bromide on. This bromide concentrations on the surface of Silberhalogeniökörner are "as already described, independent of a possible content of bromide of the silver halide grains »

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The same procedure can be used to separate the iodine precipitate, ie. Corresponding iodides can be used. It has been found to be expedient to add about 0.002 to about 0.03 moles of a water-soluble iodide salt per mole of silver to the emulsions. Particularly advantageous results are obtained when the water-soluble iodide is used in concentrations of from about 0.003 to about 0.012 moles per mole of silver. For example, it is possible to add potassium iodide to the emulsion in concentrations of about 0.5 to 5 g per mole of silver. In other words, from about 0.002 to about 0.03, and preferably from about 0.003 to about 0.012 moles of iodide per mole of silver are deposited on the surface of the silver halide grains.

As already stated, there is on the surface of the silver halide grains a bromide precipitate or a bromide and Iodide precipitate produces regardless of whether in the Silver halide grains bromide or iodide is present for example in the form of silver chlorobromide, Silver chloroiodide or silver chlorobromoiodide.

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It was also surprising to find that the Only then can increase the sensitivity of the emulsion lets when very specific electron acceptors or halogen acceptors are used. It has shown that the suitable electron acceptors and halogen acceptors in the simplest way by their polarographic half-wave potentials, d. H. their Oxidation and reduction potentials, determined on polarographic way.

Halogen acceptors have proven to be particularly advantageous those proved to have an anodic polarographic potential of less than 0.62 and a cathodic potential have a polarographic potential which is more negative than -1.3.

The cathodic measurements can be carried out with 1 10 molar solutions of the acceptors in solvents, such as, for example, methanol, which is 0.05 molar with respect to lithium chloride. A dripping mercury electrode can be used, the polarographic half-step potential for the most positive cathodic wave being denoted _{by E n.} The anodic measurements can be carried out with

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1 χ 10 molar aqueous solvent solutions, for example methanolic solutions of the acceptors, which are 0.05 molar with respect to sodium acetate and 0.005 molar with respect to acetic acid, using an electrode made of pyrolytic graphite, the voltometric half-wave potential for the most negative anodic response being denoted by E. An aqueous silver-silver chloride (saturated potassium chloride) electrode at 20 ^° C. can be used as a comparison electrode for the measurements. Electrochemical measurement methods of this type are known and are described, for example, in the book "New Instrumental Methods in Electrochemistry," by Delahay, Interscience Publishers, New York, 195 ¹ I; in the Kolthoff and Lingane book "Polarography", 2nd Edition, Interscience Publishers, New York, New York, 1952; as well as in the journal "Analytical Chemistry", ^ §. $ ^{2l <26} (1961) and 30, 1576 (1958).

The signs of the measured values are given in accordance with the Stockholm Agreement of 1953 (IUPAC).

Particularly advantageous electron acceptors have proven to be those which simultaneously have such bring about spectral sensitization that the ratio of relative minus blue sensitivity to relative Blue sensitivity of the emulsion is greater than 7, preferably greater than 10, if the emulsion is exposed to tungsten light by Wrattenfliter No. 16 or No. 35 + 38A

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is exposed. Such electron acceptors can be referred to as “spectrally sensitizing electron acceptors” ^1. However, electron acceptors which do not bring about any spectral sensitization can of course also be used.

A particularly advantageous class of electron acceptors consists of cyanine dyes, in particular Imidazo ^ jS-b ^ iquinoxaline dyes. Dyes this Class are described for example in the Belgian patent specification 660 253. With these dyes is the imidazoj_4,5-b] quinoxaline nucleus through the 2-carbon atom of the core bound to the methine chain.

Particularly advantageous results are also obtained with dyes with an indole nucleus which is substituted in the 2-position by an aromatic radical, ie for example cyanine dyes which have an indole nucleus which is substituted in the 2-position by an aromatic radical. Advantageously, such dyes also contain a desensitizing nucleus in addition to the indole nucleus "Under a desensitizing nucleus is a _t understand such the after conversion into a symmetrical carbocyanine dye, and adding to a silver chlorobromide emulsion

with 40 MoI-? Chloride and 60 MoI-Si iodide in one concentration from about 0.01 to about 0.2 grams of dye per mole of silver by electron uptake or capture leads to at least an 80, preferably greater than 90 or 95, loss of blue sensitivity.

A particularly advantageous class of spectral sensitizers Electron acceptors for the preparation of a direct positive silver halide photographic emulsion according to the invention can be represented by the following general formula:

A-L-b

where mean:
L is a methine chain having 2 to 3 carbon atoms;

A is an indole nucleus, which is in the 2-position by an aromatic Radical is substituted and which is bonded to the methine chain through its 3-carbon atom and

B is an organic heterocyclic nucleus consisting of a desensitizing core with the formation of an asymmetrical dimethine cyanine dye, when L is a methine chain with 2 carbon atoms or which consists of an indole nucleus in the 2-position is substituted by an aromatic radical, and that attached to the methine chain by the 3-carbon atom

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is bonded when L is a methine chain with 3 carbon atoms is.

A particularly advantageous desensitizing nucleus for the case that L is a nethine chain with 2 carbon atoms is an imidazo \ u, 5-bjquinoxaline nucleus which is bonded to the methine chain through the 2-carbon atom.

Spectrally senslbilislerende electron acceptors this Types can be prepared by conventional methods known for the preparation of spectral sensitizing dyes will.

A suitable method for the production of such electron acceptors is to use a carboxaldehyde i vat an indole substituted in the 2-position by an aromatic radical with an alkyl-substituted one quaternary salt of a compound with the desired one deaensitizing core in a suitable solvent to heat to reflux temperature. For example, a suitable electron acceptor can be produced in this way by refluxing an indole-3-carboxaldehyde with an aromatic radical in the 2-position together with a 2-alkyl imidazo [^, 5-quinoxalinium salt or a 2-alkylenepyrrolo | j2,3-bJpyridine in a solvent such as for example acetic anhydride.

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A particularly advantageous class of electron acceptors, which at the same time spectrally sensitize, can be passed through reflect the following general formula:

L = L-C

7'n

here mean:

a methine group which may optionally be substituted by an alkyl radical or aryl radical, d. H. for example, a methine group of the following formulas:

-CH =, -C (CH ₃ ) =, -C (C ₆ H ₅ ) =;

an aromatic nucleus, such as a phenyl nucleus, which may be optionally substituted can, for example, by alkyl radicals, for example methyl, ethyl, propyl or butyl radicals, or by Alkoxy radicals, e.g. B. methoxy, ethoxy, propoxy or butoxy radicals or halogen atoms, such as 3rom, chlorine or fluorine atoms or aryl radicals, such as, for example, phenyl radicals; However, A can also be a heterocyclic aromatic ring with preferably 5 to 6 ring atoms, the hetero atom preferably from a nitrogen, sulfur or

Consists of oxygen atom;

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R and R are each hydrogen or halogen atoms, such as for example chlorine | Bromine or fluorine atoms or alkyl or alkoxy radicals, such as methyl, ethyl, propyl, butyl, methoxy, Propoxy or hydroxyethyl radicals or together the atoms which condensed to complete one aromatic ring with 6 carbon atoms are required;

R _{1 is} an alkyl radical which can optionally be substituted with preferably 1 to 8 carbon atoms, for example a methyl, ethyl, propyl, butyl, octyl or sulfoalkyl radical, e.g. B. a sulfopropyl or sulfobutyl radical or a sulfatoalkyl radical, e.g. B. a sulfatopropyl or sulfatobutyl radical or a carboxyalkyl radical, e.g. B »a carboxyethyl or a carboxybutyl radical;

₁ J and R ₁ . optionally substituted alkyl radicals, preferably with 1 to 18 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, see-butyl, hexyl, dodecyl, octadecyl, benzyl, β-phenylethyl radicals or sulfoalkyl z, ty "Sulfatobutylrestej or Carboxyalkylreöte such as Carboxyathyl- or Garboxy * - z butylrestej Allylrestei.cAXkenylreste ^» · B, Propenyt -. or ButenyIrrstei Alkynylresto, jz "B * Propargyli Cyeloalkylreste, z, B» Gyclobutyl- barren

90 0 δ4 1Ί 0 80 t

Cyclohexyl radicals; Dialkylaminoalkyl radicals, ζ. Β. Dlraethylaminoäthylreste or aryl radicals, such as. B. phenyl, p-tolyl, S ^ -dichlorophenyl- or o-tolyl radicals;

Rg is equal to R ~ or together with FL is an alkylene radical, for example a trimethine or diinethine residue;

R _{7 is} a halogen atom or a -CN or -N0 "radical; η = 0, 1, 2 or 3 and

X is an anion, preferably an acid anion, such as a chloride, bromide, iodide, p-toluenesulfonate, Thiocyanate, sulfonate, methyl sulfate, ethyl sulfate or perchlorate anion.

There is a very similar class of extremely advantageous spectral sensitizing electron acceptors from so-called pyrroles [_2,3-bJpyrido dyes, i. e. Dyes represented by the following formula II;

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here mean:

R ₁₂ , R ₁ O and R _are each alkyl groups, such as, for example

Methyl, ethyl, propyl or butyl radicals or aryl radicals, such as, for example Phenyl radicals;

L and X have the meanings already given

and

Q is a radical of the formula -L = Q ₁ , wherein Q ₁

stands for the atoms which are necessary to complete a desensitizing nucleus with formation of a trimethine dye, ie for example a 6-nitrobenzthiazole nucleus, a 5-nitroindolenine nucleus, an imidazo JjI, 5-bJquinoxaline nucleus or a pyrrolo [2,3-bjpyridokernes, for example of the following formula III:, _{R 16 R-}

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in which R ₁₅ , R ₁ ^ and R _{17 have} the meaning given for R ₁₂ , R ₁₃ and R ^ or in which Q can also stand for the atoms which are necessary for the completion of a desensitizing nucleus with the formation of a dimethine cyanine dye, for example those for completion a pyrazole nucleus or an indole nucleus which is substituted in the 2-position by an aromatic radical and which is bonded to the methine chain through the 3-carbon atom, for example the atoms required to complete a nucleus of the following formula IV:

IV

R,

wherein R ₁ , Rp, R ^ and Rg have the meaning already given.

Another class of particularly advantageous spectrally sensitizing electron acceptors can be passed through reflect the following general formula V:

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wherein

X ₁ L, A, R ₁ , Rp, R- and Rg have the meaning already given and in which A., Rg, Rq, R ₁₀ and R _{11 also} have the same meaning as A, R ₁ , R ₂ , Ro

and Rg and wherein further Y represents a hydrogen atom, an aryl radical, for example a phenyl radical, an alkyl radical, e.g. B. a methyl, ethyl, Propyl or butyl radical or an alkoxy radical, e.g. B. a Methoxy, ethoxy or propoxy radical, an optionally substituted phenyl radical or a heterocyclic radical aromatic radical, such as a thiophene radical. Dyes of this type can be followed, for example the method described in U.S. Patent 2,930,694 produce.

Particularly advantageous electron acceptors are also the symmetrical imidazo [jl, 5 -bjchinoxal int rime thincy anine dyes, in which each nucleus is bound to the methine chain by its 2-carbon atom. Such dyes can be given by the following general formula VI:

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herein, X, L, R ^ and R_ have those already given Meaning;

R ₁₁ and R ₁₉ have a meaning corresponding to R ₁ . and R ₅ and

X is a halogen atom, for example a bromine, chlorine or fluorine atom and

η = 0, 1, 2 or 3..

Dyes of this type are for example in the
Belgian patent 660 253.

Another class of particularly advantageous electron acceptors are pyrazolyi dyes, which by the following general formula VII can be reproduced:

... Γ ι

Ϊ »i ¹⁸

Λ *

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here R ₇ , η, R ₁₄ , R ₅₈ L and X have the meaning already given and R ^ n and R. » are hydrogen atoms, alkyl radicals, preferably with 1 to 18 carbon atoms, for example methyl, butyl, octyl, dodecyl or octadecyl radicals or aryl radicals such as phenyl, p-tolyl or Sj ^ radicals and

R ₂₀ corresponds to Rj ..

Dyes of this type can by conventional methods for the manufacture of photographic sensitizers. One suitable method is, for example therein, in a suitable solvent such as acetic anhydride, a 2-alkylimidazo [j4,5-bjquinoxalinium salt with a pyrazole-4-carboxaldehyde to heat to reflux temperature.

A typical representative of this class of dyes is 1,3-diallyl-2-L2 _r (3,5-dimethyl-l-phenyl-l | -pyrazolyl) -vinyIJ-imidazoL ^ jS-bjquinoxalinium iodide of the following general structural formula VIII:

VIII CH ₂ = CHCH ₂ CH ₃

CH ₃ = CHCH ₂

CH ₃ 909847 / Q8Q7

This dye can be prepared, for example, by heating 1,3-diallyl-2-methylimidazo [^ 1,5-t> '] -quinoxalinium-p-toluenesulfonate and 3 »5-dimethyl-1-phenylpyrazole-JJ-carboxaldehyde in acetic anhydride to reflux temperature, with, for example, heating times of 10 minutes are suitable.

Another class of particularly suitable spectral sensitizers Electron acceptors are dyes substituted by at least one nitro radical, such as, for example Cyanine dyes and merocyanine dyes in which at least one nucleus, preferably both nuclei, has a desensitizing agent -NO- have remainder.

Other particularly advantageous electron acceptors consist of the reaction products of cyanine dyes with a halogen or a halogenating compound. Particularly advantageous electron acceptors of this type are those in which a hydrogen atom of at least one methine group of the cyanine dye is replaced by a halogen atom having an atomic weight of about 35 to about 127; i.e. H. is replaced by a chlorine, bromine or iodine atom. Possibly a Koaenstoffatom that connects the two nuclei with each other also have two halogen atoms.

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Particularly advantageous electron acceptors of this type can be identified by the following two structural formulas Play IX and X:

AX ZX + Z

ζβτ \ I / φ

ι y-1 2

^X 2 Α ^θ

here mean:

Z ₁ and Z ₂ each represent the non-metallic atoms required to complete a heterocyclic nucleus, such as those normally found in cyanine dyes, that is to say, for example, a nucleus of the benzothiazole series, e.g. B. a benzothiazole-i 4-chloro-benzothiazole-; 5-chlorobenzothiazQl-i 7-chlorobenzothiazole-; 4-methylbenzothiazole-j 5 "methylbenzothiazole-j 5-bromobenzothiazole" j il-phenylbenzothiazole-; 5 "Phenylbenzothiazol-j 6" Phenylbenzothiazole-J 4-MethQxybenzothiazol-s 5-MethoxybenziofchIazoi-j 5-Jodobenzothlazol "j ^ -ethoxybenzothiazol-J S-ethoxybenzothlazol-j or S-hydroxybenzothiagolringes;

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a ring of the benzoxazole series, e.g. B. a benzoxazole; 5-chlorobenzoxazoi-; 5-methylbenzoxazole-; 5-phenylbenzoxazole-; 5-methoxybenzoxazole-; 5-methoxybenzoxazole or 5-hydroxybenzoxazole ring;

a ring of the naphthoxazole series, e.g. B. one α-naphthoxazole or β-naphthoxazole ring;

a ring 8es of the benzoselenazole series, e.g. ß · one Benzoselenazole-; 5-chlorobenzoselenazole-; 5-methylbenzoselenazole or 5-hydroxybenzoselenazole ring;

a ring of the naphthoselenazole series, e.g. B. one ot-naphthoselenazole or ß-naphthoselenazole ring;

a ring of the quinoline series, including 2-quinolines, e.g. B. a quinoline; 3-methylquinoline-; 5-methylquinoline-; 7-methylquinoline-; 8-methylquinoline-; 6-chloroquinoline-; 8-chloroquinoline-; 6-methoxyquinoline-j 6-hydroxyquinoline- or 8-hydroxyquinoline ring;

of a ring of the quinoline series, e.g. B. a quinoline; 6-methoxyquinoline-; 7-methoxachinolln- or 8-methoxyquinoline ring or a ring

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of the isoquinoline series, ζ. B. a 1-isoquinoline or 3-isoquinoline ring;

L is an optionally substituted methine radical; j X _{2 is} a chlorine, bromine or iodine atom;

X ₁ and X each hydrogen atoms or chlorine, bromine or iodine atoms, where at least one of the substituents X or X _{1 is} a chlorine, bromine or iodine atom;

R ₁ and R _{2 are} each alkyl radicals, preferably short-chain alkyl radicals, such as methyl, ethyl, propyl, isopropyl, butyl, sec * butyl, tert. Butyl radicals and the like or sulfoalkyl radicals in which the alkyl group has 1 to ^ carbon atoms, such as sulfomethyl, sulfoethyl, sulfopropyl or sulfobutyl radicals or carboxyalkyl radicals in which the alkyl group preferably has 1 to 4 carbon atoms, such as carboxymethyl, carboxyethyl, Carboxypropyl or carboxybutyl radicals;

A is an acid anion, for example a chloride, Bromide, iodide, p-toluenesulfonate, thiocyanate, Methyl sulfate, ethyl sulfate or perchlorate anion;

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- 2k -

y = 1, 2 or 3 and

d, m, η and ρ each 1 or 2.

Halogen-containing dyes of the type described can be easily prepared by halogenating one Cyanine dye with chlorine, bromine or iodine or another halogenating compound, for example with Using an aqueous alcoholic, for example methanolic or ethanolic solution of the halogen or N-chlorosuccinimide, N-bromosuccinimide, N-iodosuccinimide or a commercially available halopyrrolidone complex, for example a bromo-pyrrolidone complex (manufacturer General Aniline and Film Corp. UNITED STATES).

By halogenating the dyes at least e ^ n Hydrogen atom of the methine chain replaced by a halogen atom. In the case of carbocyanines and dicarbocyanines it is believed that the halogen substitution occurs on the terminal carbon atoms of the methine chain.

The electron acceptors and halogen acceptors can be in very different concentrations can be applied. The electron acceptors are preferably in concentrations from about 100 mg to about 2 g per mole of silver halide is used. Particularly beneficial results are obtained when using from about 300 to about 600 mg electron acceptor

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achieved per mole of silver halide. Typical examples of particularly advantageous electron acceptors are:

1,1-dimethyl-2,2 ¹ -diphenyl-3,3 ¹ -indolocarbocyanine bromide;

2,2'-di-p-methoxyphenyl-1,1'-dimethyl-3,3'-indolocarbocyanine bromide;

1,1'-dimethyl-2,2 ', 8-triphenyl-3,3'-indolocarbocyanine perchlorate;

1,3-diallyl-2- \ 2- {9-methyl-3-carbazoly1) vinyI-imidazole, S-bJquinoxalinium-p-toluenesulfonate; 1,3-diethyl-l ^l -methyl-2 ^l -phenylimidazo [il, 5-b_] quinoxalino-3'-indolocarbocyanine iodide

11! "3 " 3 "-Tetraethylimidazole ¹ !, 5-bl quinoxalinocarbocyanine chloride

6-chloro-1 * -methyl-1,2 ^f , 3-triphenylimldazo | ^ 4,5-bJ quinoxalino-3'-indolocarbocyanine-p-toluenesulfonate;6,6'-dichloro-1,1 »» 3,3 * -tetraphenylimidazo \ Ji »5-bquinoxalino carbocyanine-p-toluenesulfonate;

1,1 ', 3', 3'-tetramethyl-2-phenyl-3-indolopyrrolo \ 2 , 3 - ^] -pyridocarbocyanine iodide;

lsl ^f »3» 3,3 ', 3'-hexamethyIpyrrolo [2,3-pyridocarbocyanine perchlorate;

1,1 ', 3 »3-tetramethyl-5-nitro-2'-phenylindo-3'-indolocarbocyanine iodide;

l, l ^f , 3 »3» 3 ', 3'-hexamethy1-5 »5'-dinitroindocarbocyanine ptoluenesulfonate;

3'-ethyl-1-methyl-2-phenyl-6 · -nitro-S-indolothiacarbocyanin iodide;

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5 ^f -chloro-1,3 ^f -dimethyl-2-phenyl-6'-nitroO-indolocarbo- 'cyanine-p-toluenesulfonate;

5,5 · -dichloro-3,3 ^f -diethyl-6,6 · -dinltrothiacarbocyaninjodid; Pinacryptol yellow;
5-m-nitrobenzylidene rhodanine;
5-m-nitrobenzylidene-3-phenylrhodanine;

1,3-diallyl-2- [2- (3,5-dimethyl-1-phenyl-4-pyrazolyl) vinyl] imidazo [4,5-b-quinoxalinium iodide;

3-ethyl-5-m-nitrobenzylidene rhodanine; 3-ethyl-5- (2,4-dinitrobenzylidene) rhodanine; 5-o-nitrobenzylidene-3-phenylrhodanine; l _"> 3-diethyl-6-n31rothia" 2 ^l -cyaninjodid;

6-chloro- ¹ i-nitro-benzotriazole-6-amino-1-methyl-2-fl ¹ -raethyl-6'-quinolinium) vinyl] quinolinium dichloride; 4- (pn-amyloxyphenyl) -2,6-di (p-ethylphenyl) thiapyrylium perchlorate and the like.

A class of particularly advantageous halogen acceptors for the production of direct-positive photographic silver

emulsion
halide of the invention are spectral sensitizing merocyanine dyes of the following formula:

/ C.
I. / - I.
/ B.
t
ν -C : = (LL =) _n

here mean:

the atoms required to complete an acidic heterocyclic nucleus, e.g. B. the atoms that

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Completion of a rhodanine or a 2-thiohydantoin nucleus is required;

B the atoms which are to complete a heterocyclic nucleus with a basic nitrogen
atom required Afceftg » ie for example the atoms that are required to complete a benzothiazole, naphthothiazole or benzoxazole nucleus;

L is an optionally substituted methine residue, d. H.

for example a methine residue of the following structural formulas:

-CH =, -C = or -C =

I I

CH ₃ C ₆ H ₅

η = 0, 1 or 2.

Particularly advantageous halogen acceptors derived from merocyanine dyes exist, can also be represented, for example, by the following structural formula:

RN- (LL) _t -C = (LL) = CC = O

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here mean:

m = 1, 2 or 3;

R is an optionally substituted alkyl radical preferably having 1 to 8 carbon atoms, d. H. for example a methyl, ethyl, propyl, butyl, octyl or Suifoalkylrest, z. B. a Sulfopropyl or sulfobutyl radical or a sulfatoalkyl radical, e.g. B. a sulfatopropyl or sulfatobutyl radical or a carboxyalkyl radical, e.g. B. a Carboxyäthyl- or Carboxybutylrest or one Aryl radical, which can optionally be substituted, for example a phenyl, sulfophenyl, carboxyphenyl or tolyl radical;

L is an optionally substituted methine radical; η = 1, 2 or 3;

Z to complete a 5- or 6-link heterocyclic ring required atoms, d. H. for example the atoms that are required for Completion of a Benzothiazole Benzoxazole} Benzoselenazole α-Naphthothiazole-; ß-naphthothiazole-; α-naphthoxazole-; β-naphthoxazole - ^ - naphthoselenazole-; ß-naphthoselenazole-; Thiazoline or thiazole nucleus,

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.- 29 -

ζ. B. a 4-methylthiazole, 4-phenylthiazole or 4- (2-thienyl> -thiazole nucleus or a nucleus the selenazole series, e.g. 3. of a 4-methylselenazo- or a 4-phenylselenazole nucleus or one Core of the oxazole series, e.g. B. a 4-methyloxazole or 4-phenylthiazole nucleus or a nucleus of Quinoline series or a nucleus of the pyridine series or a nucleus of the 3 »3-dialkylindolenin series and

Q the non-metallic atoms that are required to complete a heterocyclic nucleus with 5 atoms in the nucleus, d. H. for example one Rhodanine nucleus, a 2- ^ 10-2.4 (3,5J-OXaZoIdIOnkernes, a 2-thiohydantoin nucleus or a 5-pyrazolone nucleus.

A particularly advantageous class of halogen acceptors can be represented by the following structural formula:

NO

R-N C = (CH-CH) = C C = S

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here mean :.

R is in each case an alkyl radical which can optionally be substituted and preferably 1 to 8 carbon has atoms, such as a methyl, ethyl, propyl, butyl or octyl radical or a Sulfoalkyl radical, e.g. B. a sulfopropyl or sulfobutyl radical or a sulfatoalkyl radical, e.g. B. a Sulphatopropyl or sulphatobutyl radical or a carboxyalkyl radical, e.g. B. a carboxyethyl or Carboxybutyl radical or an aryl radical which can also optionally be substituted, e.g. B. a Phenyl, sulfophenyl, carboxyphenyl or tolyl radical;

η = 1 or 2;

Z necessary to complete a heterocyclic nucleus with 5 to 6 atoms in the ring Atoms, where the ring can have one of the meanings already given and

X is a sulfur or selenium atom or a residue of

Formula -NR where R is an alkyl radical which is optionally substituted and preferably 1 to 8 Has carbon atoms, i. E. for example a methyl, ethyl, propyl, butyl or octyl radical or a sulfoalkyl radical, e.g. B. a sulfopropyl or sulfobutyl radical or a sulfatoalkyl radical,

909847 / QÖ07

ζ. B. a sulfatopropyl or sulfatobutyl radical or a carboxyalkyl radical, ζ. B. a carboxyethyl or carboxybutyl radical or an optionally substituted aryl radical, e.g. B. a phenyl, sulfophenyl, Carboxyphenyl or tolyl radical.

Suitable processes for the preparation of dyes des described type used to produce a direct positive photographic silver halide emulsions according to the invention are, for example, in U.S. Patent Nos. 2,493,7 ^ 7 and 2,493,7 * »8.

Particularly advantageous halogen acceptors for the preparation of a direct-positive photographic silver halide emulsion according to the invention are for example:

3-carboxamethyl-5-f (3-ethyl-2-benzothiazolinylidene) ethylidene] rhodanine; 3-ethyl-5-L (3-ethyl-2-benzothiazolinylidene) ethylidene] rhodanine; 3- (2-dimethylaminoethyl) -5- [n- (3-ethyl-2-benzothiazolinylidene) -2-butenyldenjrhodanine; 3- & thyl-5 - [(3-ethyl-2-benzoxazolinylidene) ethylidene-jrhodanine; 3-carboxymethyl-5-Γί 3-ethyl-2-benzoxazolinylidene) ethylidene | rhodanine; 3-carboxymethyl-5 - [(3-methyl-2-thiazolidinylidene) -l-methylethylidene rhodanine; 3-carboxymethyl-5- (3-ethyl-i-methyl- ¹ ! -Thiazolin-2-ylidene) rhodanine; 5 - {_ (3-methyl-2-thiazolidinylidene) -l-methylethylidene] -3- (2-sulfoethyl) rhodanine; 3-ethyl-5- | jL- (4-sulfobutyl) -4- (IH) -pyridylidenjrhodanine; Sodium salt;

90 9-8 47/0807

3-Ethy1-5- (1-ethyl-4 (IH) -pyridylidene) rhodanine 3-Ethy1-5_ £ (3-ethyl-2-benzothlazolinylidene) ethylidene] -2-thio-2, ⁱ J-oxazolidendione; 3-carboxymethyl-5- | _ (3-ethyl-2-benzoxazolinylidene) ethylidene-2-thio-2,4-oxazolidinedione; 3-Xthyl-5- [(3-ethylnaphth [2,1-oxazolin-2-ylidene) ethylidene]-2-thio-2, ^ - oxazolidinedione; 1-carboxymethyl-5 - [_ (3-ethyl-2-benzothiazolinylidene) ethylidene] -3-phenyl-2-thiohydantoin; l-carboxymethyl-5- || (ethyl-2-benzoxazolinylidene.) ethylidene-3-phenyl-2-thiohydantoin; 1-carboxymethyl-5 - [(1-ethylnaphtho- [1,2-d] thiazolin-2-ylidene) ethylidene] 3-phenyl-2-thiohydantoin; 3-heptyl-5- (1-methylnaphtho [1,2-dJ thiazolin-2-ylidene) -l-phenyl-2-thiohydantoin; 5 - IjU - C 3-Ethy 1-2-benzoxazolinylidene) -2-butenylideneJ -1,3-diphetyl-2-thiohydantoin; i <- [(l-Ethylnaphtho [1,2-d] thiazolin-2-ylidene) methylethylidene] -3-methyl-1- (^ l-sulfophenyl) -2-pyrazolin-5-one; l-Äthoxycarbonylmethyl-S-LCL äthylnaphtho- [l, 2-d] thiazolin-2-ylidene) äthyllden] -3- ⁽ⁱ i-nitrophenyl) -2-thiohydantoinj 5-Q- (3-ethyl-2-benzothiazolinylidene ) -2-butenylideneJ -3-heptyl-2-thio-2, ^ - oxazolidinedione; 5- [(1,3-diallylimidazo \ ji, 5-bJ quinoxaline-2 (3H) -ylidene) ethylidene] -3-ethyrhodanine; 3-Ethyl-5- (3-methyl-2-thiazolinylidene) ethylidene -2-thio-2, ¹ l-oxazolidinedione 5- [(3- (2-carboxyethyl) -2-thiazolinylidene) ethylidene] -3-ethylrhodanine ; 5 - [(3-methyl-2-thiazolidinylidene) -lmethylethylidenj-3- (2-morpholinoethyl) rhodanine; 5-j_ (3- (2-carboxyethyl-2-thiazolidinylidene) -1-methylethylideneJ 3-carboxymethy! Rhodanine; 5- L (3- (2-carboxyethyl) -2-

909847/0807

thiazolidinylidene) -1-methyläthylidenj-3- (2-methoxyethyl) rhodanine; 3- (3-Dlmethylaminopropy 1) -5-J_ (3-methyl-2-thiazolidinylidene) ethylideneJ -rhodanine.

The halogen acceptors used according to the invention can can be used in different concentrations. However, it has proven to be useful to use them in concentrations from about 200 mg to about 1.0 g, preferably from about 300 to about 600 mg per mole of silver halide.

According to a special embodiment of the invention the direct positive photographic silver halide emulsion contains both an electron acceptor and also a halogen acceptor.

The water-soluble bromide can be added to the emulsion prior to the addition of the electron acceptor or halogen acceptor be admitted. However, very particularly advantageous results are obtained when the halogen acceptor or the electron acceptor can be added to the emulsion prior to the addition of the water-soluble bromide. To the To increase the sensitivity it is not necessary that between addition of halogen acceptor or electron acceptor and bromide salt is paused. It has been found to be useful while stirring the emulsion first add the halogen acceptor or electron acceptor and then immediately add the bromide

90 984 7/0807

while continuing to stir without pausing. Of course, you can choose between adding each Additions can also be paused.

The direct positive silver halide photographic emulsion of the invention can be fogged in the usual manner be, d. H. exposure to light or exposure to chemical fogging agents. It has proven to be particularly advantageous if the silver halide grains are chemically fogged will. The customary known chemical concealers can be used for concealment can be used, such as, in particular, reducing compounds, e.g. B. stannous salts, such as stannous chloride, Formaldehyde, thlourea dioxide and the like.

According to a particularly advantageous embodiment of the In the invention, the silver halide grains are formed by a reducing compound and a compound of a metal, which is more electropositive than silver, veiled. The combination has proven to be a particularly advantageous combination from thiourea dioxide and a gold salt, for example Potassium chloroaurate. The use of potassium chloroaurate is also used, for example, in the British Patent 723 019.

909847/08

In addition to the compounds listed, suitable chemical fogging agents are, for example, hydrazine, a wide variety of other sulfur compounds, phosphonium salts and z. B, tetra (hydroxymethylphosphonium chloride and the like. Compounds of metals which are more electropositive than silver are compounds of, for example, gold, rhodium, platinum, palladium, iridium and the like. These compounds are preferably used in the form of water-soluble salts, ie for example in the form of potassium chloroaurate , Aurichlorid, (NH ^ JpPdCl ₁ , and the like ».

The concentration of the concealing agents can be very high to be different. When using a reducing compound and a noble metal compound, it has become Proven to be useful, about 0.05 to 40 mg reducing Compound per mole of silver halide and 0.5 to 15.0 mg of noble metal compound per mole of silver halide. Particularly beneficial results are obtained using very low concentrations of the obscurant achieved"

The silver halide grains of direct positive photographic Silver halide emulsions of the invention are said to be so fogged that they have a density of at least 0.5 when the emulsion is applied to a carrier in a thickness of from about 50 to about

500 mg of silver per 0.0929 m (1 square foot) in one

9098A7 / 0807

usual carrier 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 silver halide emulsion of the invention may be based on silver halide grains of various constructions and types as used in known silver halide emulsions. This means that the silver halide grains of the direct-positive photographic silver halide emulsion according to the invention can also consist of a core consisting of a water-insoluble silver salt and an outer shell consisting of a fogged water-insoluble silver salt which develops into silver without exposure. Emulsions of this type, ie emulsions with silver halide grains of a layered structure, are described, for example, in US Pat. kH8 467 described.

909847/0 8 07

The shell of such grains can be produced by precipitating a light-sensitive, water-insoluble silver salt, which can be veiled and whose veil can be removed by a bleaching process, onto the cores of a so-called core emulsion. The shell should be so thick that the developer can penetrate during the The development process of the emulsion down to the core is prevented. The surface of the silver salt shell is veiled in order to make it developable into metallic silver with a conventional surface developer. The silver salt of the sheath is sufficiently obscured so that a density of at least about 0.5 is formed when the emulsion after application mg on a support in a thickness of 100 per 0,0929 m (1 square foot) for 6 minutes at 20 ⁰ C is developed in a developer of the following composition:

Developer B

N-methyl-p-aminophenol sulfate 2.5 g

Ascorbic acid 10.0 g

Potassium metaborate 35 »0 g

Potassium bromide 1.0 g

Made up to 1.0 liter with water

PH value . 9.6

90 9 8 47/0807

Such concealment can be caused by chemical sensitization to haze with the sensitizing agents Compounds are effected which are also used for chemical sensitization of the core emulsion can or the concealment can be done by exposure to high intensity light. While the nuclei do not need to be sensitized to veil, the shell is veiled. One Concealment with exposure to a reduction sensitizer, a concealment by the action of a precious metal salt, such as a gold salt and a reduction sensitizer, a fogging by exposure to a sulfur sensitizer, due to high pH values and low pAg values in the precipitation of the silver halide and the like has proven to be particularly advantageous.

If necessary, the cover can also be concealed after applying the emulsion to a carrier.

Before the shell of water-insoluble silver salt on the silver salt cores is generated, the core emulsion is first chemically or physically in a known manner treated in order to create centers on the nuclei, which cause the excretion or deposition of photolytic silver favor or promote, d. H. so-called latent image core centers are generated. Such centers can can be generated by various methods. Suitable

9098 ^ 7/0807

Methods are described, for example, in US patent application serial no. Ms 467 described. Particularly Cores which have centers made of metals from Group VIII of the periodic have proven advantageous System of elements, d. h * Centers made of palladium, iridium or platinum as these centers act as electron acceptors at the same time.

Chemical sensitization techniques such as those used for example by Antoine Hautot and Henri Saubeneir in the journal "Science et Industries Photographiques", Volume XXVIII, January 1957, pages 1 to 23 and 57 to are described to be particularly advantageous proven. Such chemical sensitizations can practically be divided into three main classes, namely in a sensitization by means of a noble metal compound, a sensitization with a Sulfur compound, d. H. especially a sensitization with a compound having a labile sulfur atom and reduction sensitization, d. H. one Treatment of the silver halide with a strongly reducing compound which leaves small spots or spots metallic silver into the silver salt grain or the silver salt crystal.

909847/0807

According to a particularly advantageous embodiment of the invention, the direct-positive photographic silver halide emulsion of the invention has silver halide grains which have a simple structure, ie do not have a layered structure and do not consist of a core and shell and which contain an electron acceptor, the silver halide grains being fogged only to the extent that that a photographic silver halide emulsion prepared from the grains and applied to a support, if it is for 6 minutes at a temperature of 20 C in a developer of the following composition:

Water, 52 ° C 500 cm ^ N-methyl-p-aminophenol sulfate 2.5 g

Sodium sulfite (dehydrated) 30.0 g, hydroquinone 2.5 g

Sodium metaborate 10.0 g potassium bromide 0.5 g

Made up to 1.0 liter with water

developed to a maximum density of at least about 1 has a maximum density that is at least is about 30X greater than the maximum density of a reference sample, which developed under the same conditions

9098A7 / 08Ö7

after being in a for 10 minutes at 20 ° C Bleaching bath of the following composition:

Potassium cyanide 50 mg glacial acetic acid 3.47 cm ³

Sodium acetate - 11.49 g

Potassium bromide 119 mg made up to 1.0 liter with water

has been bleached.

The grains of such emulsions lose at least about 25%, as a rule at least 40%, of their haze when they ^{are bleached for 10 minutes at 20 °} C. in a potassium cyanide bleach bath of the specified composition. This loss of fog can 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 after 6 minutes of development at about 20 °} C. in developer A and comparing the density of the emulsion with a corresponding one Emulsion layer, the 6 minute! developed in Developer A for about 10 minutes at 20 ° C after being bleached for about 10 minutes at 20 ° C in the potassium cyanide bleach bath of the specified composition. As already stated,

909847/0807

If the maximum density of the unbleached emulsion layer is at least about 3O] E ₉ , as a rule at least βθ% greater than the maximum density of the bleached layer «

The silver halide grains of direct positive photographic Silver halide emulsions of the invention can consist of the usual silver halides, however, the halide is at least 50 HoI-JE from Should consist of chloride. I. E. the silver halide grains can for example consist of silver chloride, Süberchlorobromid, Silcherchlorobromojodld and the like. Emulsion mixtures can also be used; H. Mixtures of silver chloride and silver chlorobromide. Also, in the case of a layered structure of the grains of one, the grains of the silver halide grains Silver halide, which is different from the silver halide from which the outer shell is formed. In any case, however, the total amount of chloride should be at least 50 MoI-JE

Particularly good results are obtained when the silver halide grains have an average grain size of less than 1 micron, preferably less than about 0.5 micron. The silver halide grains can have the usual structure, d. H. the silver halide grains can have the various known shapes,

§09847 / 0807

as used in silver halide photographic emulsions are common

According to a particularly advantageous embodiment of the invention possess at least 80 wt .- # or SOjC the number of silver halide grains of the emulsion a regular, preferably a cubic regular or an octahedral structure · Especially advantageous is also preferred if at least 95 wt. - % of the silver halide grains of the emulsion have a diameter that does not deviate by _{more than -HOt 9,} preferably by no more than -30% _t, from the mean Komduehmesser

The mean grain diameter can be determined by known, customary methods, as described, for example, in the magazine "The Photographic Journal", Volume LXXIX ₉ 1949 »Rare 330 to 338.

The fogged silver halide grains of such direct-positive photographic silver halide emulsions of the invention produce a density of at least 0.5 if, without being exposed, Developed in developer A for 5 minutes at 20 ° C when in the form of an emulsion at a strength of 50 to about 500 mg of silver per 0.0929 -m (1 square foot} to be applied to a trägex ^.

909847/0807

The silver halide grains of direct positive photographic Silver halide emulsions according to the invention are expediently used in layer thicknesses of 50 to 500 mg Silver applied per 0.0929 m (1 square foot) of a support.

In the production of a direct positive photographic Silver halide emulsion according to the invention is expediently proceeded in such a way that the electron acceptor, the halogen acceptor, the bromide and the iodide of the washed, finished silver halide emulsion are added and distributed as well as possible in the emulsion will. The usual procedures for incorporation can be used of additives in silver halide photographic emulsions. For example catfish it has proven to be useful proved to add the additives in the form of solutions in suitable solvents to the emulsion. Suitable Solvents are, for example, methanol, isopropanol, Fyrldln, water or mixtures thereof. Such solutions or solvent systems are excellent for incorporating the electron acceptors and halogen acceptors.

The binders of the silver halide emulsions can be made from the usual ones for the preparation of photographic silver halide emulsions used hydrophilic colloids exist, d. H. for example from natural materials,

909847 / Q8Q7

such as gelatin, albumin, agar-agar, gum arabic, Alginic acid and the like, or from hydrophilic synthetic ones Plastics, such as polyvinyl alcohol, polyvinylpyrrolidone, cellulose ethers, partially hydrolyze cellulose acetates and the like. The binders can furthermore be dispersed polymerized vinyl compounds such as those described in U.S. Patents 3,142,568; 3,193,386; 3,062,674 and 3,220,844. These polymers include, for example, water-insoluble polymers made from alkyl acrylates and alkyl methacrylates, Acrylic acid, sulfoalkyl acrylates and sulfoalkyl methacrylates.

The direct positive silver halide photographic emulsions according to the invention can be coated on the usual photographic supports, i.e. H. for example on supports made of glass, film bases, for example on films made of cellulose acetate, cellulose acetate butyrate, Polyester, such as polyethylene terephthalate, on a paper backing, on a backing Barytized paper, on a carrier made of paper coated with a polyolefin layer, for example on a carrier with a polyethylene layer or a polypropylene layer and the like. The carrier optionally with Electrons may have been irradiated to improve the adhesion of the emulsion to the support.

9098A7 / 0807

The following examples are intended to illustrate the invention in more detail. In the examples, the bromides and iodides are added following the addition of the halogen acceptor or electron acceptor, if nothing else is stated.

Example 1 shows the considerable improvement in sensitivity that is achieved in accordance with the invention that a soluble bromide salt is added to a fogged direct positive emulsion, the silver halide grains thereof a halogen content of at least 5035 Have chloride and wherein the silver halide grains have a halogen acceptor or an electron acceptor.

The example also demonstrates the improvement in maximum density achieved when using iodide salts can be used in combination with bromide salts. The example also illustrates the use of a Bromides alone, d. H. in the absence of a halogen acceptor or an electron acceptor in which Case no increase in sensitivity is achieved.

909847/080?

example 1

First, a Gelatlne-Sllberchloridemulsion was prepared with an average grain size of about 0.3 microns, by spraying an aqueous solution of potassium chloride and an aqueous solution of silver nitrate equal to each other under vigorous stirring to an aqueous gelatin solution of a temperature of 70 ⁰ C within a Zeitrauaes of 35 Hinuten The emulsion was then quenched, noodled and washed with cold water in order to leach out water-soluble salts in the usual way.

The EmuMon was then veiled by first adding 0.2 mg of thiourea fdioxy-t per pint of silver, while ^{heating the emulsion to 65 °} C. for 60 minutes, by further adding 0.0 mg of potassium chloroaurate per mole of silver and, meanwhile, the emulsion also being 60 Was heated to 65 ^{0 C for minutes}

The emulsion was then divided into several parts, whereupon the parts halogen acceptors, electron acceptors, potassium bromide and potassium iodide, as in Table I below, has been added.

The resulting emulsions were then coated on cellulose acetate film support with comparative emulsions so that a support area of 0.0929 m ² (1 sq.ft.)

909847/0807

ORIGINAL

100 mg of silver and 350 mg of gelatine were used. After the emulsion layers had dried on, the films obtained were exposed in an intensity scale sensor, developed for 3 minutes at 65 ^° C. in a conventional developer (Kodak D-19), fixed, washed and dried. The following results shown in Table I were obtained. The sensitivities were read at 0.3 below D _χ

Table I.

Halogen or
Electrons
acceptor
(g / mole Ag) KI g /
Mol Ag KBr g /
Mol Ag Relative
Sensation
opportunity ^D raax ^{in 1} ^ ¹ -
exposed
Districts «Wn ^ln
exposed
Districts Without .... <0.15 1.1 1.05 Without 1 * 0 - <0.15 1.33 1.36. Without - 8.76 <0.15 1.27 1.25 Without 1.0 8.76 <0.15 1.25 1.12 K1.5) - - 2.4 1.07 0.04 K1.5) 1.0 ~ 0.51 1.41 0.07 K1.5) ~ 8.76 15.9 1.24 0.04 1 (1.5) 1.0 8.76 11.0 1.27 0.05 11 (1.0) ~ - * 0.15 1.19 0.84 11 (1.0) 1.0 ~ 1.2 1.27 0.04 11 (1.0) - 8.76 • MM 0.11 0.04 11 (1.0) 1.0 8.76 15.1 1.26 0.04

909847/0807

111 (0.5) iii (0.5) 111 (0.5) 111 (0.5)

1.0

1.0

- - 1.1 1.32 0.80 - - <0.15 1.24 1.07 8th .76 42.0 1.16 0.22 8th .76 53.0 1.26 0.42

The following example 2 illustrates the particularly advantageous effects that are achieved when the addition of the halogen acceptor or electron acceptor before the addition of the soluble bromide or optionally takes place before adding the bromide and iodide. It can be seen from the example that the increase in sensitivity is even greater if the bromide or the bromide and iodide are added to the emulsion before the Addition of the electron acceptor or halogen acceptor he follows.

Example 2

After the procedure described in Example 1, a Emulsion made with grains an average grain size of 0.7 microns. The emulsion was then in divided into several shares. The different proportions were halogen or electron acceptors in the The concentrations given in Table II below were added. The addition of the halogen or Electron acceptors before or after the addition of potassium iodide or potassium bromide. During the addition of the acceptors ^ and Salts, the emulsion was stirred vigorously, whereby

909847/010 *

between the addition of electron acceptors or halogen acceptors and potassium bromide or potassium iodide, none
Pause has been taken.

The prepared emulsions were then applied to the usual film base in a thickness that
a support area of 0.0929 m ² (1 square foot) accounted for 220 mg of silver and 425 mg of gelatin. After exposure in an intensity sensor, the film specimens were developed for 3.75 minutes in a Kodak D-85 developer. The results obtained are shown in Table II below. In this
Table refers to the indication "dye on the
Halogen or electron acceptor

Table II

Halogen or
Electrons
acceptor
p / MoJ. Ap First
admitted
bene ver
bIndune KI g /
Mole Kßr g /
Mole Relative
Sensation
opportunity unexposed
Districts ^D min ^ln
exposed:
Districts 1 (1.0) - ..... -. ... 0.21 1.34. 0.93 1 (1.0) dye 8.76 .... 0.16 0.04 1 (1.0) dye 1.0 8.7 1.34 0.27 1 (1.0) dye 1.0 8.76 363 ' UIt- 0.07 1 (1.0) salt ... 8.76 22.0 ^; 0.54 0.13 1 (1.0) salt 1.0 - ·, 1.3 1.42 0.21 Loo) salt 1.0 8.76 60.0 0.78 0.22 IIK0.5) dye ... 0.76 1.32 0.67 IIK0.5) dye ...... 4 * 38 240 0.74 0.08

909847/0807

copy

IIK0.5) dye 1.0 4.38 0.63 1.46 1.0 111 (0.5) dye 1.0 4.36 138 1.20 0.08 111 (0.5) Sals ... - 331 1.48 0.8 ΙΪΙ (0.5) salt .1.0 4.38 0.95 1.51 1.0 111 (0.5) salt 1.0 ... 60.0 1.46 0.09 IV (0.5) dye ... 4.38 58 1.50 0.63 IV (0.5) dye ... 4.38 795 0.90 0.06 IV (0.5) dye 1.0 120 1.66 0.15

Example 3 below illustrates the preparation a rectilinear photographic silver halide emulsion of the invention, the grains of which are composed of a central Core made of a water-insoluble silver salt with centers, which favor the deposition of photolytic silver and an outer shell made of water-insoluble veiled silver salt, which can be developed into silver without exposure to light.

Example 3

A gelatin silver chloride emulsion was prepared by simultaneous addition within a tent room of 20 minutes of 1000 ml of a 4 molar silver nitrate solution and 1000 ml of a 4 molar sodium chloride solution EU of a vigorously stirred aqueous solution of 1000 ml a 0.01 solar sodium chloride solution containing 40 g of belatine

9098A7 / 0807

and had a temperature of 70 ° C. Then 5000 ml of water with a content of 280 g of gelatin were added added, whereupon the resulting emulsion was cooled.

1/8 of the gelatin Silberchloridemulslon obtained (with 0,5MoI-? Silver chloride) was melted at 40 ° C, whereupon 100 mg of a water soluble iridium salt and indeed Kaliumchloroiridit, were dissolved in water was added, and the emulsion was heated to 70 ⁰ C. .

The emulsion prepared was a silver chloride core emulsion represented, the nuclei exhibiting physical discontinuities for accepting or capturing electrons. The nuclear envelope made of silver chloride was then applied to these cores by adding 500 ml of a ^ molar Silver nitrate solution and 500 ml of a 4 molar sodium chloride solution at the same time to the core emulsion within a period of 20 minutes. The silver chloride of the shell was then fogged by adding 0.2 mg of thiourea dioxide per mole of silver to the emulsion, applying the emulsion for 60 minutes 65 ° C., 4.0 mg of potassium chloroaurate per mole of silver were added to the emulsion and the emulsion continued for another 60 minutes was heated to 65 C. Then 16O g of gelatin, previously soaked in 3 ^ 10 ml of water, were stirred into the emulsion, whereupon the resulting emulsion was cooled.

BATH ORIGINAL 909847/0807

Silver nitrate was added both during the formation of the core emulsion and during the production of the shell and. sodium chloride in a constant ratio.

To form the shell, sufficient silver chloride was used that a ratio of 4 moles of silver chloride in the shell to one mole of silver chloride in the core.

The emulsion obtained was then melted, whereupon the gelatin content was increased to 160 g per mole of silver chloride became. Further water was then added so that there were 4,000 g of water for 1 mol of silver chloride.

The emulsion was then divided into several parts, whereupon electron acceptors, Halogen acceptors, potassium iodide and potassium bromide in the in the proportions given in Table III below were added. The various emulsions were then applied to conventional cellulose acetate film supports in such a way that on a support surface of 0.0929 m (1 square foot) 180 mg of silver and 400 mg of gelatine were used. After the emulsion sheets were dried, they were obtained Test specimens exposed in a sensitometer and then for 30 seconds in a Kodak D-72 developer, diluted with an equal volume of water. The specimens were then treated in the usual manner

fixed and washed and dried. The received Erin
The results are compiled in Table III below:

90 98 47/080?

Table III

Halogen or electron acceptor
(g / mol Ag)

1 (1.0)
1 (1.0)
1 (1.0)
1 (1.0)

V (I.0)
V (I.0)
V (I.0)
V (I.0)

VI (I.0)
VI (I.0)
VI (I.0)
VI (I.0)

VII (I.0)
VII (I.0)
VII (I.0)
VII (I.0)

VIII (I.0)
VIII (I.0)
VIII (1.0)
VIII (1.0)

IX (I.0)
IX (I.0)

KI (g / MoI Ag)

1.0 1.0

1.0 1.0

1.0 1.0

1.0 1.0

1.0 1.0

1.0 1.0 Relative

KBr (g / Sensitivity MoI Ag) ability

4.38 4.38

4.38 4.38

4.38 4.38

4.38 4.38

4.38 '4.38

4.38 4.38

4.38

71.0
48.0
50.0
80.0

<12.6
550.0
36.0
759.0

15.5
398.0
▼ 12.0
501.0

<12.0
302.0

T12.0
479.0

<12.0
32.0

27.5
1450.0

42.0
302.0

27.5
501.0

<12.0
115.0

Dmax ⁱⁿ 'Dmin ⁱⁿ !'! Exposed exposed districts districts

1.
1.
1.
1.

78
66
58
60

1.54
1.12

1.
1.

1.
1.

1.

39
39

52
46
40

1.44

1.32
1.10
1.40
1.32

1.24
0.34
1.54
1.16

1.30
1.26
1.14
1.28

1.40
1.22

0.06 0.56 0.06 0.06

1.45 0.03 0.11 0.03

1.22 0.02 1.34 0.02

1.30 0.03 1.36 0.03

1.16 0.03 1.01 0.03

0.15 0.04

0.23 0.06

1.31 0.13

90984 7/0807

COPY

IX (I.O) 1.0 - ■ U.38 17.5 1.40 0.88 ix (i.α) 1.0 4.38 - 110.0 1.28 0.10 X (I.0) • MW » - U, 38 <12.0 1.25 1.25 X (I.0) - 4.38 - 15.9 0.56 0.26 X (I.0) 1.0 U.38 <12.0 1.26 1.18 X (I.0) 1.0 1157.0 0.78 0.02 111 (0.5) 501.0 1.29 0.05 111 (0.5) - 2290.0 1.07 0.03 111 (0.5) 1.0 603.0 1.27 0.08 111 (0.5) 1.0 2890.0 1.38 0.04

The following Examples 4 and 5 illustrate the

Production of a uniformly fogged silver chlorobromide emulsion, the halide of the silver chlorobroraid grains being 90 Mo] -% chloride.

Example 4

After an emulsion described in Example 1 was prepared in procedures with the exception, however, that as much of potassium bromide was added during the precipitation of the Silberchlorobromides that the halogen content of the grains to 90 MOI? consisted of chloride. The emulsion obtained was then divided into several portions , whereupon various amounts of halogen acceptors and electron acceptors and potassium bromide were added to these portions. The emulsions

90984 7/0807

COPY

were then so on to conventional cellulose acetate film supports

ρ applied that 100 mg of silver and 370 mg of gelatin were accounted for on a support area of 0.0929 m (1 square foot). The specimens were then exposed and developed in the manner described in Example 1, however this time the development time was 1 minute. The results obtained are shown in Table IV below compiled:

Table IV

Halogen or
Electrons
acceptor
(g / mol Ag) KBr g /
Mol Ag Relative
Sensitive
speed ^D max ⁱⁿ
unexposed
Districts Dmin ¹ ^ ¹
exposed
Districts 1 (0.5) 7.3 1.18 0.06 1 (0.5) 8.76 115.0 1.10 0.02 111 (0.5) __ 100.0 1.58 0.80 111 (0.5) 8.76 117.0 1.31 0.05

Example 5

Following the procedure described in Example 3, a gelatin-silver chlorobromide emulsion with a Chloride content of 90 MoI-? made, each time such sodium bromide and sodium chloride ratios were used as to add the halide to the core emulsion 90 MoI-Ji consisted of chloride and the halide of the shell the grain was also formed from 90 MoI-Ji chloride.

9098A7 / 08G7

The resulting emulsion was then divided into several proportions divided, whereupon an electron acceptor or a halogen acceptor was incorporated into these emulsion portions and with and without the addition of potassium bromide. The emulsions obtained were then described as in Example 4 tested. The results given in Table V below were obtained.

Halogen or electron acceptor KBr g / (g / mol Ag) mol Ag

K0.5) 1 (0.5)

111 (0.5) 111 (0.5)

4.38

4.38

Table V Dmax in ^D min in Relative unexposed exposed Sensation Districts Districts opportunity 1.50 1.4 0.55 1.34 0.04 7.6 1.42 0.07 100.0 1.17 0.07 263.0

The following example 6 shows that electron acceptors are also suitable which are not themselves Are dyes.

909847/0801

Example 6

There was an emulsion as described in Example 2, produced and divided into several parts. Various proportions of the emulsion then became the compound I incorporated the composition given below, which itself is not a dye but an electron acceptor is. The compound I was introduced into emulsion fractions with and without the addition of potassium iodide. The various emulsion fractions were then applied to film supports in the usual manner and as in Example 2 described tested. The following results were obtained:

Halogen or
Electron acceptor Ki
(g / mol Ag) g / mol

Table VI

Relative I ^ _ax in DmI _n in KBr g / sensitivity unexposed exposed mol ility districts districts

link
(0.5) I. - 4th .38 0. 19th 1 .62 1 , 2 link
(0.5) I. 1.0 4th .38 - 0 .07 0 .03 link
(0.5) I. 18th 0 1 .08 0 .04

The Halogenak ^ eptQren and used in the examples Electron acceptors consisted of the following compounds;

909847/0807

Dye I.

Dye II
Dye III

Dye IV

Dye V

-59 -

1,3-diethy1-1 »-methyl-2'-phenylimidazo- _> 5-b-quinoxalino-3 ¹ -indolocarbocyanine-iodide (electron acceptor)

Pinacryptol yellow (electron acceptor)

3-carboxymethyl ~ 5- \ i 3-methyl-2 (3) -thlazolinyliden) isopropylidenj rhodanine (halogen acceptor)

3-ethyl-5- [l- (M-sulfobutyl) -k (IH) -pyridylidene] rhodanine, sodium salt (halogen acceptor)

2-L2- (3 _t 5-dimethyl-1-phenyl- ⁱ t-pyrazolyl) -vinylj-1,3-diphenylimidazo [4,5-b-quinoxalinium iodide (electron acceptor)

Dye VI

Dye VII

3 - [(1,3-Diethyl-2 (IH) -imidazo [ii, 5-b] quinoxalinylidene) ethylidene] -2H-pyridoLl, 2-a] pyrimidine-2,4- (3H) -dione (electron acceptor)

3-ethyl-2 - [(2-methyl-5-oxo-3-phenyl-3-isoxazolin-iJ-yl) vinylj -o-nitrobenzothiazolium methyl sulfate (Electron acceptor)

Dye VIII 1,1 », 3,3,3 ', 3'-hexamethyl-5,5'-dinitro-

indocarbocyanine p-toluenesulfonate (Electron acceptor)

ORIGINAL INSPECTED
9 09 8A7 / 0 807

Dye IX

Dye X

5,5 * -Dichloro-3,3'diethyl-6,6 »-dinitrothiacarbocyanine iodide (Electron acceptor)

3- [(3-Ethyl-6-nitro-2-benzothiazole: inylene) ■ ethylidene] -2H-pyrido [1,2-a] pyrimidine-2,4 (3H) -dione (Electron acceptor)

Compound I.

1,1 · diethyl-2,2 ^f -cyanine chloride, dibrominated. I. E. _t the carbon atom connecting the two nuclei had 2 bromine atoms.

Results similar to those described in Example 1 were obtained with a silver chloride emulsion made with High intensity light has been obscured or with an emulsion made by using a reducing compound alone, d. H. For example, stannous chloride was obscured.

Excellent results have also been obtained when a combination of halogen acceptors and electron acceptors was used on the surface of the silver halide grains.

9098A7 / 0807

Claims (1)

Claims (1./Direct positive photographic silver halide emulsion V / with silver halide grains that are veiled and the halide of which consists of at least 50 mol% chloride and a content of an electron or halogen acceptor, characterized in that the silver halide grains have on their surface: (a) An electron acceptor with anodic and cathodic polarographic potentials that add up and/ result in a positive sum / or a halogen acceptor with an anodic polarographic potential of less than 0.85 and a cathodic polarographic potential that is more negative than -1.0 and (b) a ßromide precipitate and optionally also an iodide precipitate. 2. Direct positive photographic silver halide emulsion according to claim 1, characterized in that the silver halide grains on its surface, 0.01 to 0.2 moles of bromide per mole of silver and optionally also 0.002 contain up to 0.03 moles of iodide. 9098A7 / 0807 3 «Direct positive silver halide photographic emulsion according to claims 1 and 2, characterized in that the silver halide grains on their surface per mole Silver 0.04 to 0.09 moles of bromide and optionally also contain 0.003 to 0.012 moles of iodide. H, direct positive photographic silver halide emulsion according to claims 1 to 3 »characterized in that the silver halide grains are chemically fogged. 5. Direct-positive photographic silver halide emulsion according to Claims 1 to 4, characterized in that the halide of the silver halide grains consists of at least 80 mol # of chloride. 6. Direct-positive photographic silver halide emulsion according to Claims 1 to 5 »characterized in that the silver halide grains of the emulsion by a reducing fogging agent and a compound of a metal, which is more electropositive than silver, veiled and veiled. 7. Direct positive photographic silver halide emulsion according to claim 6, characterized in that the silver halide grains are obscured by a reducing fogging agent and a gold compound. 90984 7/0807 Ib 4.7 78 8 8. Direct-positive photographic silver halide emulsion according to Claims 1 to 7 »characterized in that the silver halide grains contain a photographic sensitizing dye as an electron acceptor, which spectrally sensitizes the emulsion in such a way that the ratio of relative minus blue sensitivity to relative blue sensitivity is greater than 7. 9. Direct-positive photographic silver halide emulsion according to claim 7 »characterized in that the silver halide grains are veiled with thlourea dioxide and potassium chloroaurate. 10. Direct positive silver halide photographic emulsion according to claims 1 to 9, characterized in that at least 80% by weight or 80% by weight of the number of silver htlogenide grains of the emulsion have a regular, preferably a regular cubic structure. 11. Direct-positive silver halide photographic emulsion according to claims 1 to 10, characterized in that the silver halide grains act as electron acceptors (A) a dye with at least one indole nucleus which is substituted in the 2-position by an aromatic radical is, - (b) a dye with an imidazole4,5-b \ quinoline core, L -J (c) a pyrazolyl dye, (d) a dye with a pyrroloJ_2,3-bj pyridokern, (e) a dye having a nitro group or 9098A7 / 0807 IHSPECTEO (f) contain a halogenated cyanine dye. 12 «Direct-positive photographic silver halide emulsion according to Claims 1 to 10, characterized in that the silver halide grains contain a halogen acceptor of the following formula: B C = (L-L) = C C = O ι * η * / * J ^s Λ ^ * where mean: L is a methine residue; B required to complete a heterocyclic ring with a basic nitrogen atom Atoms; A are the atoms required to complete an acidic heterocyclic ring and η = 0, 1 or 2. 13. Direct-positive photographic silver halide emulsion according to claim 11 ^, characterized in that the silver halide grains contain 1,3-diethyl-1 »-methy1-2 · -phenylmidazo \ ß , S-bJchlnoxalino-S * -indolocarbocyanine iodide as electron acceptor. 909847/0807 '! 547788 14. Direct positive silver halide photographic emulsion according to claims 1 to 10, characterized in that the silver halide grains are 3-carboxymethyl-5 - [(3-methyl-2 (3) -thiazolinylidene) isopropylidene-rhodanine as the halogen acceptor contain. 15. Direct positive silver halide photographic emulsion according to claims 1 to 14, characterized in that at least 95% by weight of the silver halide grains of Emulsion have a diameter which does not deviate by more than -403 »from the mean grain diameter. 16. Direct-positive photographic silver halide emulsion according to claims 1 to 15, characterized in that the silver halide grains are fogged only to such an extent that a photographic silver halide emulsion prepared from "the grains and coated on a support, when it is stored for 6 minutes at a temperature of 20 ⁰ C in a developer of the following composition: Water, 52 ° C N-methyl-ρ-aminophenol sulfate Nätriümsülfit Hydroquinone Topped up with water mi 500 , 5 cm-* 2 »0 G 30th , 5 G 2 , 0 S. 10 , 5 G O , 0 1 liter ORIGINAL 547788 developed to a maximum density of at least about 1 has a maximum density that is around at least about 30? is greater than the maximum density a comparative sample developed under the same conditions after being at 20 ° C for 10 minutes in a bleach bath of the following composition: Potassium cyanide glacial acetic acid Sodium acetate Potassium bromide Made up with water 50 mg 3.47 cm ³ 11.49 g
119 mg 1.0 liter has been bleached. ORIGINAL