DE1547859B1 - Silver halide photographic emulsion - Google Patents

Description

C-CH = C-CH = C

C-CH = C-CH = C

Χ ^Θ

contains, in which R ¹ , R ² , R ³ and R ^{4 are} each optionally substituted by hydroxyl alkyl group, where at least one of the radicals R ¹ and R ² in formula (I) and at least one of the radicals R ³ and R ⁴ in formula ( II) a carboxymethyl, / 9-carboxyethyl, 2- (2-carboxyethoxy) - ethyl, y-carboxypropyl, jö-sulfoethyl, 2-ethyl [2- (3-sulfopropoxy) ethoxy] ethyl , γ-sulfopropyl, 2-hydroxy-1-sulfopropyl, 3-methoxy-2- (3-sulfopropoxy) propyl, 2-hydroxy-3- (3'-sulfopropoxy) propyl or <5-sulfobutyl group and X® denotes an anion which is omitted in the presence of a betaine structure.

The invention relates to a black and white photographic silver halide emulsion formed by at least two thiacarboxycyanine dyes are spectrally oversensitized.

Spectrally sensitized silver halide photographic emulsions, which do not contain any color couplers and 2,2'-dialkyl-8-alkyl-thiacarbocyanines as sensitizers (e.g. 4,4'-dichloro-2,2 ', 8-triethylthiacarbocyanine chloride) and 2,2'-dialkyl-8-alkyl-3,4,3', 4'-dibenzthiacarbocyanines (e.g. 2,2'-dimethyl-8-ethyl-3,4,3 ', 4'-dibenzthiacarbocyanine iodide) contained in combination are known from GB-PS 4 98 289.

It is also known from DE-PS 9 72 811 that the sensitivity of gelatin silver bromide iodide emulsions that do not contain color couplers and act as red sensitizers following 8 - ethylthiacarbocyanine dyes of the following formulas

C-CH = C-CH = C

C ₂ H ₅

contains, drops from 425 to 325 or from 480 to 240 if the gelatin silver bromide iodide emulsion contains compounds as red sensitizers instead of the aforementioned compounds in which, apart from the lack of the iodine anion, the ethyl groups on the ring nitrogen atoms are each replaced by the group - CH ₂ - CH ₂ - COOH are replaced.

The object of the invention is to provide those known from GB-PS 498 289 which do not contain a color coupler spectrally oversensitized photographic emulsions

sions with regard to their oversensitization effect to improve further.

This object is achieved in that the silver halide emulsion at least one spectral sensitizer of the following general formula (I) and at least one spectral sensitizer of the following general formula (II)

C ₂ H ₅

C-CH = C-CH = C

X =

contains, in which R ¹ , R ² , R ³ and R ⁴ each represent alkyl groups optionally substituted by hydroxyl, where at least one of the radicals R ¹ and R ² in formula (I) and at least one of the radicals R ³ and R ⁴ in formula ( II) a carboxymethyl, ß-carboxyethyl, 2- (2-carboxyethoxy) ethyl, γ-carboxypropyl, ß-sulfoethyl, 2 - ethyl [2 - (3 - sulfopropoxy) ethoxy] ethyl, v-sulfopropyl , 2-hydroxy-I-sulfopropyl, 3-methoxy-2- (3-sulfopropoxy) propyl, 2-hydroxy-3- (3'-sulfopropoxy) propyl or d - sulfobutyl group and X® is an anion, which does not apply in the presence of a betaine structure.

The invention achieves that the red sensitivity is increased more than the green sensitivity, the sensitizers used having a satisfactory diffusion resistance exhibit.

The ratio of the amount of the spectral sensitizer according to formula (I) to the amount of the spectral Sensitizer according to formula (II) according to the invention is not subject to any particular restriction and can can expediently be varied in the range from 9: 1 to 1: 9.

The spectral oversensitization according to the invention is indicated by the simultaneous presence of a compound with an acid group, ζ. B. a sulfonic acid or a carboxyl group such as a surface active agent, a high molecular one Sensitizer or a flocculant hardly disturbed.

Typical examples of spectral sensitizers used according to the invention are listed below.

C ₂ H ₅ C-CH = C -C =

(I-a)

C ₂ H ₅

C-CH = C-CH = C

(I-b)

(CH ₂ ) ₂
COOH

CH, CH, OH

C ₂ H ₅ C-CH = C-CH = C

(I-c)

(CH ₂ ) ₃
SO ₃ H · NC ₅ H ₅

C ₂ H ₅

. C-CH = C-CH = C

(I-d)

(CH ₂ CH ₂ O) ₂ - (CH ₂ J ₃ SQ ^ C ₂ H ₅ (CH ₂ CH ₂ O) ₂ - (CH ₂ ) ₃ SO ₃ Na

"C-CH = C-CH = C

C-CH = C-CH = C

S \ I / S \ / \

_e C-CH = C-CH = C

The invention is explained in more detail below using the example.

example

To 100 g of a gelatin silver bromide iodide emulsion with 6.0 mol% AgI, prepared by a customary process, the Snesibüisatoren (Ia) and / or (II-a) were added in the amounts given in Table I below. The mixture was then ^{stirred for 60 minutes at 40 °} C. to stabilize the spectral sensitization effect. After adding a hardener, the emulsion was applied directly to a layer support and dried.

The resulting. Recording material was cut into strips, that a red exposure through a red filter and a green sub exposure through a green filter using a sensitometer with a color temperature of about 4800 ⁰ K

Tabetfe-I

40

45

50 (II-c)

(CH ₂ ) ₃
SO ₃ HN (C ₂ Hs) ₃

designed and developed thereafter in a black and white developer of the following composition for 20 minutes at 2O ⁰ C.

Black and white developer

N-methyl-p-aminophenol sulfate 4 g

Sodium sulfite 50 g

Hydroquinone 5 g

Sodium carbonate (monohydrate) 40 g

Potassium bromide 5 g

Potassium thiocyanate 1.0 g

Potassium iodide (0.1% by weight) 5 ml

made up to 1 liter with water

pH 10.2 ± 0.1

Then it was fixed. The results are in the table below compiled.

sample 0.0Qlmofare 0.001 square meters Relative green » Relative red Sensitive No. Solution of the Solution of the sensitivity sensitivity ization Sensitiv ·. Sensjbili- niaxitnum gators (ta) satprs (Il-a) in methanol in MethanoF wr inni) 1 2 α 23.5 too 652 2 4th 0 35.5 140 654 J Θ 2 20.5 140 682 4th 0 4th 26.5 175 684 5 2 2 390 250 675

The results with similar but not according to the invention sensitizers are used for comparison the following formulas in Table II below.

'S _n 1 / S _n A

C-CH = C-CH = C Jl I

. ; ^ν νλΑ

α I I ei

C ₂ H ₅ C ₂ H ₅

Br

"C-CH = C-CH = C

Br

Table II

sample 0.001 molar 0.001 molar Relative green Relative red Sensitive No. Solution of the Solution of the sensitivity sensitivity ization Sensitive Sensitive maximum sators (A) sators (B) in methanol in methanol (ml) (ml) (nm)

4th
0

4 2

25 20 32

100

74

130

652
675
668

From the results in Table II it can be seen that, as can be seen from Table I, i-ί was according to the invention

that when using the sensitizers A and B, the nitrogen atoms neither by a carboxyalkyl nor are substituted by a sulfoalkyl group, the relative increase in red and green sensitivity was approximately the same. On the other hand 4 <>

if the sensitizers (I-a) and (II-a) are used at the same time, the sensitivity to red is considerably increased with a relatively small increase in green sensitivity.

809 582/5

Claims (1)

Claim: Black and white silver halide photographic emulsion formed by at least two thiacarbocyanine dyes is spectrally oversensitized, characterized by the fact that it is at least a spectral sensitizer represented by general formula (I) below and at least a spectral sensitizer represented by the following general formula (II)