DE1547643C3 - Direct post photographic material - Google Patents

Description

= CH-CH = C ⁷ \ / V

H ₃ CC

CH,

and a nitrostyryl dye of the formula

NO ₇

--Ö

contains.

contains.

10. Direct positive photographic material according to claims 1 to 4, characterized in that it is a methine dye of the formula

CH

and a nitrostyryl dye of the formula

CH,

V-CH = CH

NO,

contains.

11. Direct positive photographic material according to claims 1 to 4, characterized in that it is a methine dye of the formula

O -Cl CH ₃ \ CH-C /
: h = c N H ₃ c-c- CH / K CH ₃ N ⁺ / V J- <U

The invention relates to a direct positive photographic material and in particular a direct positive emulsion with one in the visible spectral range improved sensitivity.

It is known that by using the Herschel effect or the solarization effect directly can lead to positive photographic images.

During solarization, the image is reversed due to excessive exposure; is a layer up to pre-exposed to the greatest possible blackness, this decreases according to the further exposure. At the Herschel effect is a developable blackening produced by an exposure second exposure to light of greater wavelength weakened. The decrease in blackening takes place in contrast to solarization, this happens immediately at the beginning of the second exposure. She is independent on the size of the blackening of the first exposure. In both cases attempts have been made to use the photographic one To increase the sensitivity of the recording material.

The sensitizing dyes known for the spectral sensitization of negative emulsions cannot simply be incorporated into direct positive emulsions that are used in solarization technology are provided. They bring a number of serious disadvantages here, such as: B. a discoloration of the white image areas, plus a flattening of the gradation curve and / or increased blackening in the exposed parts either immediately after exposure or during storage of the Materials.

45 In order to overcome these disadvantages, the use of special sensitizing dyes has been proposed. Are interesting in this context-CH ₃ SO ₄ "hang the methine dyes and in particular the

2-phenylindole group. Dyes of this type are described in British Patents 825,965 and 970,601. Your sensitizing effect in the usual negative emulsions is weak. An increase in the sensitivity of direct positive emulsions, which are processed using the Herschel effect can be mixed with dyes that have a desensitizing effect in negative emulsions (C. E. K. M ees, The Theory of the Photographic Process, Revised Edition (1954), Macmillan Company New York, p. 263). It will be in in this context, in particular, to desensitizing dyes of the nitrostyryl and nitrobenzylidene type as described in British Patents 667,206, 698,576 and 834,839 will.

The invention is based on the object of providing a direct positive photographic material with improved Develop overall sensitivity and storage stability.

A direct positive material has now been found that can be processed using the solarization technique is determined and which is provided with a photosensitive silver halide layer, which is through Exposure or chemically obscured

N ⁺

'V

and which is a spectral sensitizing methine dye from the series of 2-phenylindole of the following formula with a desensitizing nitrostyryl or nitrobenzylidene dye:

Ph "- R ₅ = CH - N Ph ' / \ C-CH =

Z ₂

R ₁ and R ₅ here denote an optionally substituted alkyl radical of the type generally known in the chemistry of cyan dyes, such as methyl, ethyl, n-propyl, η-butyl, n-amyl, isopropyl, isobutyl, / 3-hydroxyethyl, β-acetoxyethyl, Sulfoethyl, sulfopropyl, sulfobutyl, sulfatopropyl or sulfatobutyl, an unsaturated aliphatic radical, e.g. Allyl, aralkyl, e.g. B. benzyl, a substituted benzyl radical such as carboxybenzyl, an aryl radical, e.g. B. phenyl, substituted aryl such as carboxyphenyl, a cycloalkyl group such as cyclohexyl and cyclopentyl or a substituted alkyl group such as

-A-CO-OB-SO ₂ OH

where A and B each represent a hydrocarbon radical as in British patent specification 886 271 described or the grouping

-W -NH-V -B

Ri Y- Ph ' R ₅ N L-CH- ⁺ N-, p J = CH-

, Y

H ₁ C

40

where A is a methylene, ethylene, propylene or butylene group, B is an alkyl group, an amino group, a substituted amino group or hydrogen, if V is a single bond, and W and V are each a - mean CO group, an -SO ₂ group or a single bond, but at least one of these groups is a - SO ₂ group, as described in British Patent specification 904,332; R _{2 is} hydrogen or alkyl, such as methyl, ethyl, propyl, butyl, benzyl, a cycloalkyl group such as cyclohexyl or cyclopentyl, a thienyl or R ₄ -C ₆ H ₄ radical, in which R _{4 is} hydrogen or alkyl; Ph 'and Ph "each have an optionally substituted phenyl radical, e.g. a phenyl radical substituted by alkyl, aryl, alkoxy or halogen, the substituents preferably being in the p-position; Z ₁ and Z _{2 are} the atoms necessary to form a benzene nucleus, where the nucleus can be substituted, for example, by halogen, alkyl or alkoxy and X "is an anion, ζ. B. Cl ", Br", I ", ClO ₄ , CH ₃ SO ₄ " and

so;

However, X is absent if R ₁ itself contains an anionic group.

where R ₁ , R ₅ , Ph ", Z ₁ and X have the same meaning as in formula I and Y is the atoms necessary to complete a heterocyclic nucleus customary for cyanine dyes, e.g. a nucleus from the thiazole series, e.g. thiazole, 4 - methylthiazole, 4 - methyl - 5 - carbethoxythiazole, 4 - phenylthiazole, 5 - methylthiazole, 5 - phenylthiazole, 4 - (p - tolyl) - thiazole, 4 - (p - bromophenyl) - thiazole , 4,5-dimethylthiazole, 4,5-diphenylthiazole, 4- (2-thienyl) - thiazole, 4 - (m - nitrophenyl) - thiazole, from the benzothiazole series, e.g. benzothiazole, 4-chlorobenzothiazole, 5 -Chlorobenzothiazole, 6-chlorobenzothiazole, 7-chlorobenzothiazole, 5-methylbenzothiazole, 6-methylbenzothiazole, 5-bromobenzothiazole, 6-bromobenzothiazole, 6-sulfobenzothiazole, 4-phenylbenzothiazole, 5-phenylbenzothiazole, 5-phenylbenzothiazole, 6-methoxybenzothoxy, 6-methoxybenzothoxy, 5-phenylbenzothiazole, 5-phenylbenzothiazole, 6-methoxybenzothoxy , 5 - iodobenzothiazole, 6-iodobenzothiazole, 4-ethoxybenzothiazole, 5-ethoxybenzothiazole, 4,5,6,7-tetrahydrobenzothiazole, 5,6-D ioxymethylene benzothiazole, 5-hydroxybenzothiazole, 6-hydroxybenzothiazole, 5,6-dimethylbenzothiazole, from the naphthothiazole series, e.g. B. naphtho - [2,1 - d] - thiazole, naphtho - [1,2 - d] thiazole, 5-methoxynaphtho [1,2-d] thiazole, 5-ethoxynaphtho - [1,2 - d ] - thiazole, 8 - methoxynaphtho- [2,1 - d] - thiazole, 7 - methoxynaphtho - [2,1 - d] - thiazole, from the thionaphtheno - [7,6 - d] - thiazole series, e.g. 7 - Methoxy - thionaphtheno - [7,6 - d] - thiazole, from the thiadiazole series, e.g. B. 4-phenyl-thiadiazole, from the oxazole series, e.g. B. 4-methyloxazole, 5-methyloxazole, 4-phenyloxazole, 4,5-diphenyloxazole, 4-ethyloxazole, 4,5-dimethyloxazole, 5-phenyloxazole, from the benzoxazole series, e.g. B. benzoxazole, 5-chlorobenzoxazole, 5-methylbenzoxazole, 5-phenylbenzoxazole, 6-methylbenzoxazole, 5,6-dimethylbenzoxazole, 4,6-dimethylbenzoxazole, 5-methoxybenzoxazole, 6-methoxybenzoxazole, 5-hydroxybenzoxazole, from the Naphthoxazole series, for example naphtho- [2,1-d] oxazole, naphtho- [1,2-d] oxazole, from the selenazole series, e.g. B. 4-methylselenazole, 4-phenylselenazole, from the benzoselenazole series, e.g. B. Benzoselenazole, 5-chlorobenzoselenazole, 5-methoxybenzo-

409 527/379

selenazole, 5-hydroxybenzoselenazole, 4,5,6,7-tetrahydrobenzoselenazole, from the naphtholselenazole series, e.g. naphtho- [2,1-d] -selenazole, naphtho- [l, 2-d] -selenazole, from the 2-quinoline series, ζ. B. quinoline, 3-methylquinoline, 5-methylquinoline, 7-methylchino-Hn, 8-methylquinoline, 6-chloroquinoline, 8-chloroquinoline, 6-methoxyquinoline, 6-ethoxyquinoline, 6-hydroxyquinoline, 8-hydroxyquinoline, etc., from the pyrimidine series, from the quinoxaline series, from the 1-phthalazine series, from the 2-pyridine series, e.g. Pyridine, 5-methylpyridine, 3-nitropyridine, from the benzimidazole series, e.g. B. benzimidazole, 5,6-dichlorobenzimidazole, 5-chlorobenzimidazole, 5,6-dibromobenzimidazole, 5 - chloro - 6 - aminobenzimidazole, 5 - chloro-6-bromobenzimidazole, 5-phenylbenzimidazole, 5-fluorobenzimidazole, 5,6-difluorobenzimidazole, 5-cyanobenzimidazole, 5,6-dicyanobenzimidazole, 5-chloro-6-cyanobenzimidazole, 5-fluoro-6-cyanobenzimidazole, 5-acetylbenzimidazole, 5-chloro-6-fluorobenzimidazole, 5-carboxybenzimidazole, 7-carboxybenzimidazole, 5-carbethoxybenzimidazole, 7-carbethoxybenzimidazole, 5-sulfamylbenzimidazole or 5-N-ethylsulfamylbenzimidazole.

The advantages of this combination over the 2-phenylindole dyes alone are greater Storage stability, the better whiteness in the exposed areas of the developed material and in particular in an increased overall sensitivity.

In order to form a direct positive image with the photosensitive material of the present invention, it is all that is necessary is to expose the material imagewise with white or blue light and convert it into to develop a silver shark developer solution.

In the following table 1 are some characteristic examples of dyes according to the general Formulas I and II put together:

Table 1

2.

4th

CH,

CH,

C = CH-CH = C

11th

H, CO

continuation

CH ₃

N ⁺

OCH ₃ H ₃ CO

V ⁷ c — c-

12th

CH ₃

CH = CH-

OCH,

CH ₃

N ⁺

CH ₃

C = CH-CH = CH-C

CH ₃

N ⁺

CH ₃

-C = C-CH = CH-C

\ 'V ⁷

ClO ₄ -

C = CH-CH = CH-C

OCH ₃

CH ₃

C = C CH = CH

CH ₃

13th

continuation

CH ₃ H ₃ C
CH CH = CH

CH ₃ CH ₃

V-χ /
C = CH-

14th

CH ₃

CH ₃ CH ₃

-CH = CH C

CH ₃

C == CH CH = CH C

oCH ₃ H ₃ CO

C = C CH = CH-

CH ₃

CH ₃

C = CH-CH = C
H ₃ CC

CH ₃

QH ₅

: = CH-CH = C
S-

-CH ₃

continuation

The dyes corresponding to the general formulas I and II can be according to the British Patents 825,965 and 970,601 described methods can be prepared.

Suitable nitrobenzylidene and nitrostyryl dyes are represented by the following general formulas:

CH (= CH-CH) "_ ₁ = C

(HI a)

NO,

NO,

-CH) _n _ ₁ = C '
^{0 = C} -

(III b)

CH = CH (-CH = CH) _n _! - <r Y Z ₃ j J ^ CH = CH (- CH = CH),.! -

NO,

(IV)

(V)

therein one or more of the methine groups, e.g. B. be substituted by CN; R ₁ , X ~ and Y have the meaning described above; Z ₃ represents the atoms necessary to complete an aromatic nucleus, e.g. B. a benzene nucleus which may be substituted, e.g. B. by another nitro group.

P and Q each represent an organic, electronegative one Group, e.g. B.

NOH

CR,
S.
-CR ₆

N = N

—C — SH

Il s

—C — N

R ₇

-C-SK,
S.

—C — N—

Il I

SR _a

R ₇

R «

COR ₆ R ₇ —C — N Il
0 0 R ₇ C — Ν — Ν
Il I \ -CC-OR ₆
Il Il Il I
OR Il Il
0 0

—SO ₂ R, in which R ₆ , R ₇ and R _{8 represent} hydrogen, alkyl, aryl, aralkyl or a heterocyclic radical, which radicals may be substituted, further —NO ₂ , —CN, an aromatic homocyclic monovalent radical, e.g. B. phenyl or naph- "thyl, where the radicals can preferably be substituted by an electronegative group or a monovalent heterocyclic radical with aromatic character, eg. Furyl, thienyl, pyrrolyl, indolyl or

Z '

wherein Z 'represents the atoms necessary to complete an aromatic heterocyclic ring and it is possible for these radicals to be substituted; Z ₄ denotes the atoms necessary to complete a cyclic ketomethylene nucleus, for example a nucleus from the pyrazolone series, e.g. B. 3 - methyl -1 - phenyl - 5 - pyrazolone, 1 - phenyl - 5 - pyrazolone, 1 - (2 - benzothiazolyl) - 3 - methyl - 5 - pyrazolone, from the isoxazolone series e.g. B. 3-phenyl-5-isoxazolone or 3-methyl-5-isoxazolone), from the oxindole series z. B. 1 - alkyl - 2: 3 - dihydro - 2 - oxindoles, from the 2: 4: 6-triketohexahydropyrimidine series, e.g. barbituric acid or 2-thiobarbituric acid, and their derivatives, for example the derivatives substituted in the 1-position by an alkyl group, z. B. with a methyl group, an ethyl group, a 1-n-propyl group and a 1-n-heptyl group or derivatives which are substituted in the 1- and 3-positions by an alkyl group or those in the 1- and 3-positions / 3-Methoxyäthylrest or are substituted in the 1- and 3-position with an aryl radical, such as phenyl or with a substituted phenyl radical such as p-chlorophenyl or p-ethoxycarbonylphenyl or those that are only in the 1-position by phenyl, p-chlorophenyl or p-Äthoxycyrbonylphenyl are substituted, furthermore the derivatives substituted with alkylaryl such as 1-ethyl-3-phenyl and 1-η-heptyl-3-phenyl-derivatives, further cores from the rhodanine series, e.g. B. from the 2 - thio - 2: 4 - thiazolidinedione series, such as rhodanine and aliphatically substituted rhodanines, ζ. Β. 3-ethylrhodanine or 3-allylrhodanine, those from the imidazo [l: 2-f /] pyridone series, from the 5: 7-dioxo-6: 7-dihydro-5-thiazo [3: 2-a] pyrimidine Series, e.g. 5: 7-Dioxo - 3 - phenyl - 6: 7 - dihydro - 5 - thiazol [3: 2 - a] pyrimidine, from the 2-thio-2: 4-oxazolidinedione series, e.g.

from the 2-thio-2: 4-oxazoldione series, e.g. 3-ethyl-2-thio-2: 4-oxazolidonedione, which from the thianaphthenone series, e.g. B. 3-thianaphthenone, from the 2-thio-2: 5-thiazolidinedione series, z. E.g. the 2-thio-2: 5-thiazole, e.g. the 2-thio-2: 5-thiazoldione series, e.g. 3-ethyl-2-thio-2: 5-thiazolidinedione, from the 2: 4 thiazolidinedione series, e.g. B. 2: 4-thiazolidinedione, 3-ethyl-2 ^ -thiazolidinedione. 3-phenyl-2: 4-thiazolidinedione, 3-alpha

naphthyl-2: 4-thiazolidinedione, from the thiazolidone series, e.g. B. 4-thiazolidone, 3-ethyl-4-thiazolidine, 3-phenyl -4-thiazolidine, 3-alpha-naphthyl -4-thiazolidone, from the 4-thiazolone series, e.g. B. 2-ethylmercapto-4-thiazolone, 2-alkylphenylamino-4-thiazolone, 2-diphenylamino-4-thiazolone, from the 2-imino-2: 4-oxazolidone, in particular pseudohydantoin series, from the 2: 4 imidazoline (hydantoin) series, e.g. B. 2: 4-imidazolinedione, 3 - ethyl - 2: 4 -imidazolinedione, 3-phenyl-2: 4-imidazolinedione, 3-alpha-naphthyl-2: 4-imidazolinedione, l: 3-diethyl-2: 4-imidazolinedione, 1-ethyl-3 - phenyl -2: 4- imidazolinedione, 1 - ethyl - 3 - alphanaphthyl-2: 4-imidazolinedione, 1: 3-diphenyl-2: 4-diphenyl-2: 4-imidazolinedione, from the 2-thio-2: 4-imidazolinedione, (2-thiohydantoin) series, e.g. B. 2-thio-2: 4-imidazolinedione, 3 - ethyl - 2 - thio -2: 4- imidazolinedione, 3 - phenyl - 3 - thio - 2: 4 - imidazolinedione, 3 - alpha - naphthyl - 2 - thio - 2: 4 - imidazolinedione, 1: 3- diethyl -2-thio-2: 4- imidazolinedione, 1 - ethyl-3 - phenyl - 2 - thio - 2: 4 - imidazolinedione, 1 - ethyl-3 - alpha - naphthyl - 2 - thio - 2: 4 - imidazolinedione, 1: 3-Diphenyl-2-thio-2: 4-imidazolinedione, from the 5 - imidazolone series, e.g. B. 2 - η - propyl - mercapto-5-imidazolone and homocyclic ring systems according to the following structural formulas:

Il

C-CH,

C- (CH ₂ ) ,,,
H ₂

30th

35

wherein m is 1, 2 or 3

Il

C-CH ₂

C- (CH ₂ ) _m
O

or s ~ \

= C ^X - '

= c

= c

= c

wherein m is 1, 2 or 3

η is 1 or desensitizing methine dyes that contain an aromatic nitro group can be prepared by condensation of an aromatic compound substituted with a nitro group which has an aldehyde group on the aromatic nucleus, which can also be linked to the nucleus via a methine chain, with a suitable heterocyclic compound Compound that bears an active methyl or methylene group.
Examples of desensitizing methine dyes which correspond to the general formulas mentioned are listed in Table 2 below.

Tabel

\ / ( / NO ₂ ^ H ₃ H ₅ C ₂ O- ^ 0-CH = CH- NO ₂ " QH ₅ . A. Yr ^N V-CH = CH- Jl ρ

CH ₃ SO ₄ "

Br '

continuation

CH ₃ SO ₄ -

C = S

Other suitable aromatic methine dyes having a nitro group are disclosed in British Patents 262 816, 667 206, 698 575, 698 576, 834 839, the German patent 396 402 and the USA patent 2 953 561.

When preparing the emulsion, the dyes are expediently added in the form of solutions. Suitable solvents are, for example, alcohols such as methanol or ethanol. The desensitizing one Dye is preferably used in an amount of 0.15 to 3.5 moles per mole of the optically sensitizing Dye applied, while the latter dye in an amount of 0.02 to 1 millimole per mole of silver halide is used.

In practice, 10 to 500 mg and preferably 100 to 250 mg of des is generally used spectral sensitizing dye per mole of silver halide. In special cases, however, it is also possible to use larger quantities.

The direct positive emulsions are produced according to the usual methods. You can use silver chloride, -bromide, -iodide or mixtures of the halides. Emulsions with are preferred at least 50% silver bromide. With the expression "direct positive emulsions" are obscured Emulsions which can be developed without a shimmering exposure after the imagewise exposure are.

The fogging of the emulsion can be done either by pre-exposure or by chemical means by increasing the pH value or by adding reducing agents such as tin compounds, can be achieved.

The following example shows the beneficial effect the inventive combination of spectral sensitizing compounds with desensitizing Links.

example

For each 1 kg of a washed photographic film chemically obscured with a reducing agent Emulsion containing 60 g of a silver iodide / bromide emulsion contains (95 mole percent AgBr and 5 mole percent AgI), it is applied to a cellulose triacetate support before application the amounts of the sensitizing compounds given in Table 3.

The finished emulsion layers are marked by a continuous gray wedge with the constant 0.2 exposed. It does this in two different ways. One exposes with a fluorine essence lamp, the other time with a 375 watt frosted glass bulb.

A group of emulsion strips of the same type is now after normal storage at room temperature exposed and processed, while a second group prior to exposure and processing Store for 36 hours at 34% relative humidity and 57 ° C.

A normal developer based on hydroquinone and N-methylp-aminophenyl hemisulfate is used for development used.

The total sensitivity is given in percent and based on a comparison emulsion, whose overall sensitivity was arbitrarily set at 100. The overall sensitivity is in marked with the letter S in the table. The blackening in the exposed areas is a measure for the quality of the whites and is denoted by D in the table.

Table 3

number rrm pro
60 g
Silver-
bromide Fluorescent lamp
Emulsion at room temperature stored S. emulsion exposure S. impen
emulsion D ₁ 36h at 37% r. F. S. test
series of
add
Color
substance in S. around 0.04 Stored i 57 ° C Table 1 D ₁ 100 100 D ₁ Glowh
at room temperature 100 0.04 S. 100 or 2 62 a.i3 145 0.05 stored 251 0.03 100 100 A ' I. 62 0.08 182 0.03 S. 0.03 1 31 + 31 0.08 100 100 0.03 100 100 0.03 332 100 1 + 1 62 0.09 138 0.04 240 0.01 100 263 B. I. 62 0.08 138 0.03 400 0.03 2 31 + 31 0.06 100 100 0.01 100 100 0.03 288 100 1 + 2 62 0.09 120 0.04 191 0.01 100 166 C. I. 62 0.09 126 0.03 316 0.03 3 31 + 31 0.07 100 100 0.01 100 100 0.03 191 100 1 + 3 62 0.11 100 0.05 151 0.03 100 126 D. I. 62 0.11 100 0.04 251 0.04 6th 31 + 31 0.09 100 100 0.03 100 100 0.04 174 100 1 + 6 62 0.09 120 0.05 191 0.03 100 166 E. II 62 0.07 151 0.03 209 0.05 1 31 + 31 0.06 100 100 0.2 100 100 0.02 251 100 II + 1 62 0.09 145 0.06 151 0.02 100 151 F. IV 62 0.06 126 0.02 302 0.05 1 31 + 31 0.06 100 100 0.01 100 100 0.02 251 100 IV + 1 62 0.07 166 0.05 182 0.01 100 182 G III 62 0.06 166 0.02 257 1 31 + 31 0.01 0.01 100 400 III + 1 316

Claims (9)

Patent claims: 1. Direct positive photographic material with a fogged silver halide emulsion layer; characterized in that the emulsion layer has at least one nitrostyryl or nitrobenzylidene dye and at least contains a methine dye of the following general formulas I and II: Ph "Ph" C-CH = CH
R, = CH- R _{5 s} Y Ph ' ⁺ N- CH IO 20th (H) wherein R ₁ and R _{5 represent} an optionally substituted alkyl; R _{2 is} hydrogen, alkyl, cycloalkyl, thienyl or a group R ₄ —C ₆ H ₄ , in which R _{4 is} hydrogen or alkyl; Ph 'and Ph "an optionally substituted phenyl radical; Z ₁ and Z ₂ the atoms necessary to form an optionally substituted benzene ring; Y the atoms necessary to complete a heterocyclic nucleus common in cyanine dyes; X ~ an anion. 2. Direct positive photographic material according to claim 1, characterized by a Content of at least one nitrostyryl or nitrobenzylidene dye one of the following general Formulas III a, IIIb, IV and V: Z ₃ 1 ^ -CH (= CH-CH) _n _ ₁ = C (III a) 55. NO, O = QS = CH (-CH = CH) "_! < Y (IV) CH = CHeCH = (V) wherein R _{1 is} an optionally substituted alkyl; Y the atoms necessary to complete a heterocyclic nucleus customary in cyanine dyes; Z ₃ the atoms necessary to close a benzene nucleus; P and Q each represent an electronegative organic radical; Z ₄ the atoms necessary to complete a ketomethylene nucleus; X ~ an anion; η 1 or 2. 3. Photographic direct positive material according to claims 1 and 2, characterized by a content of at least one methine dye according to the general formulas I. or II in an amount of 0.02 to 1 millimole per mole of silver halide and a nitrostyryl or nitrobenzylidene dye in an amount of 0.15 to 3.5 moles per mole of the methine dye. 4. Direct positive photographic material according to claim 3, characterized in that the silver halide emulsion layer the methine dye in an amount of 100 to 250 mg per Contains moles of silver halide. 5. Direct positive photographic material according to Claims 1 to 4, characterized in that that it is a methine dye of the formula (III b) 60 and a nitrostyryl dye of the formula 5C ₂ O- CH ₃ CH = CH— < NO ₂ H ⁴ V CH ₃ SO ₄ : 6. Direct positive photographic material according to claims 1 to 4, characterized in that it is a methine dye of the formula CH ₃ N ⁺ CH ₃ χ / C = ^ = CH CH —C
H ₃ C CH ₃ and a nitrostyryl dye of the formula CH ₃ NO ₂ H ₅ C ₂ O CH ₃ SO ₄ " contains. 7. Direct positive photographic material according to claims 1 to 4, characterized in that it is a methine dye of the formula CH and a nitrostyryl dye of the formula CH ₃ C ₂ H ₅ NO, H ₅ C ₂ O VCH = CH- /) CH ₃ SO ₄ T contains. 8. Direct positive photographic material according to claims 1 to 4, characterized in that it is a methine dye of the formula Cl CH ₃ ^Ν _χ / V-OCH ₃ , f ~ VN ⁺ C-CH = CH-C H ₃ CC and a nitrostyryl dye of the formula contains. CH ₃ NO ₂ H ₅ C ₂ O-Ws, CH ₃ CH, so; 9. Photographic direct positive material according to claims 1 to 4, characterized in that that there is a methine dye of the formula and a nitrostyryl dye of the formula NO ₂ y ν Cl CH,