CS202670B1 - Photographic emulsion on the base of the silver halogenide - Google Patents

Abstract

1496989 Photographic emulsion sensitizer FILMFABRIK WOLFEN VEB 5 April 1976 [15 April 1975] 13692/76 Heading G2C In a process for the manufacture of a photographic silver halide emulsion there is added, prior to or during the step of digesting the emulsion, as a chemical sensitizer, an asymmetric disulphide of the general Formula in which each of A and B, which may be identical or different, denotes an alkyl, aryl or aralkyl radical which radicals are unsubstituted or are substituted as indicated in the Formula; each of W and Z, which may be identical or different, denotes an unsubstituted amino group, a mono- or dialkylamino group, a trialkylammonium group, a quaternary ammonium group, a betaine group, or a mono or diacylamino group; each of X and Y, which may be identical or different, denotes a carboxy group or an alkoxycarbonyl group; and each of a, b, c and d, which may be identical or different, denotes 0, 1, 2 or 3 with the proviso that each of the sums a + d and b + c should be at least 1; with the proviso that in at least one of the pairs of symbols A/B, W/Z, X/Y, a/d and b/c the two symbols have different meanings. A noble metal compound or a reducing agent can be added as an additional sensitizer. A number of leucine derivatives are listed as examples of suitable compounds.

Description

BACKGROUND OF THE INVENTION The present invention relates to a silver halide-based photographic emulsion containing sensitizer additives to enhance sensitivity during chemical aging.

It is already known to add sulfur-containing sensitizers to the photographic emulsions to improve chemical maturation, for example symmetrical disulfides, cysteines, cystines, or their N-substituted products, reducing agents or gold compounds, or combinations thereof. This can increase the sensitivity of the photographic emulsions during aging. For many purposes, however, this increase in sensitivity achievable enough or has ^the disadvantage that it is accompanied by a strong tendency towards the formation of veils. Depending on the circumstances, this veil can also become particularly apparent only after spectral sensitization or storage.

The above-mentioned drawbacks do not have a photographic silver halide emulsion containing an additive of sensitizers for increasing sensitivity during chemical maturation, characterized in that it contains asymmetric disulfides of the formulas (W) _and (X) _b A - S - S - V (Y) _c (Z) _d , wherein A and V are C 1 -C 6 alkyl, phenyl or benzyl,

202 670

202 β70

X and a ϊ carboxyl and / or methoxycarbonyl or ethoxycarbonyl group,

V and Z are an amino group, which is optionally acetylated, methyl or ethylated, and a, b, c, d are 0 to 2, wherein a + b or b + c are 0 to 4.

The photographic emulsion may also contain noble metal sensitizers or reducing sensitizers. The disulfide is added to the emulsion in an amount of 0.5 · 10 ^-5 to 2. 10 ³ moles per mole of silver halide ·

Advantages of the emulsion according to the present invention are that a silver halo genide emulsion is obtained which has a high sensitivity and reduced veil formation, further enhancing its sensitivity and gradation.

The unsymmetrical disulfide sensitizers of the invention may be, for example

HgN - CH ₂ w CH ₂ - p - S - CH ₂ - COOH, HjC - s - with - CH ₂ - СВ (Ш ₂ ) - COOH i-C 1 - p - with - CH ₂ - CH (№ ₂ ) - COOH, н ₅ с _б - CH ₂ - with • S ch ₂ - ch (k ₂ ) - cooh, HjN - CH ₂ - s · - s - CH ₂ - CH (M ₂ ) - COOH, n-C _{7 7} - p - with - CH ₂ - CH _(NHCH3) - COOH - p - with - CH ₂ - CH (HH _2), - COOCH ₃ β n-C ₇ H ₇ - p - with - ch ₂ - CH (NHCOCH ₃ ) - COOH.

It should be noted that compounds in which W and / or Z are alkylamino groups, in addition to increasing the sensitivity at normally short exposure times, exhibit particularly good activity at long exposure times and correspondingly lower intensity.

Likewise, conventional non-clouding agents, stabilizers, spectral sensitizers, color coupling agents and other additives may be used with the emulsions prepared.

The sensitizing effect of the disulfides according to the invention is to be illustrated by the following examples.

Example 1

Emulsion 8 with silver chloride bromide, adjusted by gelatin, containing a small amount of admixtures, was divided into three parts before maturation and after the addition of various chemical sensitizers left to ripen, then returned, illuminated and finally induced.

202 670 emulsifiers were used as chemical sensitisers per kg;

Sample A: no addition

Sample B: 5 mg sodium thiosulfate

Sample C: 8.4 mg of compound 7.

Table 1 shows the results.

Table 1

Exam Maturation time (min) Veil Citl. 0.1 Citl · 1 Aging temperature (° C) Gradation AND 30 0.28 6.5 5.0 58 3.6 60 0.44 7.3 6.2 4.2 90 0.65 7.1 6.0 4.3 В 30 0.28 7.0 6.2 50 5.1 60 0.70 7.3 6.1 4.0 C 30 0.32 7.3 6.2 58 3.7 60 0.44 8.0 . 6.7 3.8 90 0.57 8.3 7.0 4.0

A sensitivity of 0.1 and 1, respectively, indicates the relative sensitivity at a density of 0.1 and 1, respectively, above the veil.

Differences from 1 mean half or double sensitivity. Developed within 5 minutes at 20 ° C in a developer having the following composition:

1.5 g of N-methyl-p-aminophenyl hydrogen sulphate g of sodium sulphite

2.5 g hydroquinone g potassium carbonate g potassium bromide dissolved in distilled water to a volume of 1 liter ·

As can be seen from Table 1, the addition of sodium thiosulphate, a widely used sulfur sensitiser in practice, under these conditions, i.e. in the absence of gold salts, results in a very rapid maturation which results even though the maturing temperature is lowered without there is an increase in sensitivity to veil formation, whereas in the presence of a labile sulfur compound of the invention, an increase in sensitivity at the start of the characteristic curve of about 2-fold can be observed without an increase in veil.

Example 2

The silver bromide chloride emulsion produced according to Example 1 is divided into 4 parts before chemical maturation and mixed with various chemical sensitizers.

202 670 ripen under the same conditions and process ee further as in example 1 ·

As chemical sensitisers, ee will use emulsions per kg:

Sample A: only complex salt of dirhodanoaurate (corresponding to 2 mg of gold) Sample B: as A with addition of 1 mg of sodium thio sulfate

Sample C: as A 8 by adding 2 mg of sodium thiosulfate

Sample D: as A but 8 by adding 20 mg of sodium thiosulfate.

The result is shown in Table 2 below

Table 2

Sample Veil Citl. 0.1 Citl. 1 Gradation AND 0.20 8.8 7.7 3.5 В 0.21 9.3 8.0 3.7 C 0.26 8.9 7.8 3.8 D 0.16 9.2 8.1 5.0

The values show only the sensitizing effect of the disulfide used as compared to the maturation carried out with the gold salt, as well as a reduced tendency to form a veil over maturation with a conventional sulfur sensitizer sodium thiosulfate.

Example 3

The same emulsion as in Example 1 is divided into 8 parts before chemical maturation and processed as in Example 1, adding the following ripening agents per kg of parts:

Test A: only the gold salt of Example 1 is present Test B: as A, but by adding 10 mg of S-methylmercapto-L-cyateine Test C: as A, but with the addition of 25 g of S-methylmercapto-L-cyeteine Test D: as A, but with the addition of 11.5 mg S-ethylmercapto-L-cyeteine Test E: as A, but with the addition of 29 mg of S-ethylmercapto-L-cyeteine Test F: as A, but with the addition of 12.5 mg of S-n-propyl mercapto-L-cyeteine Test G: as A, but with the addition of 13.5 mg of S-n-butylmercapto-L-cyeteine Test H: as A, but with the addition of 15.5 mg S-beniylmercapto-L-eysteine.

The following table 3 gives a clear overview of the sensitometric results:

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Table 3

Exam Veil Citl. 0.1 Citl. 1 Gradation AND 0.45 7.3 6.0 3.1 В 0.46 7.8 6.5 3.4 C 0.40 8.2 7.0 4.1 D 0.30 9.0 7.8 4.0 E 0.30 9.3 8.2 4.2 F 0.30 9.0 8.0 5.0 G 0.35 8.2 7.2 4.4 H 0.35 7.5 6.5 5.0

It can be seen from the table that increased sensitivity can be achieved by adding the additives according to the invention with a slight veil.

Example 4

The highly sensitive emulsion with silver iodide bromide and gelatinised gum, which was poor in accompanying substances, was subjected to chemical maturation with the additives listed below:

Test A: 6 ml of a 20% solution of benzensulfinan sodium and a complex of dirhodanoaurate corresponding to 1,6 mg gold per kg emulsion

Test B: As A except that it additionally contained 4.2 mg of N-methyl-S-n-propylmercapto-L-cysteine as a methanol solution.

The layered emulsions were illuminated

a) 1/25 seconds

(b) 30 minutes (corresponding to a lower intensity).

It was developed together for 5 minutes with the developer described in Example 1 and for 15 minutes with an additional veil call.

It can be seen from the following Table 4 that the ripening agent has a better effect under long-term illumination with a lower intensity of 2 Din compared to an increase in intensity of 1 Din in short-term illumination of higher intensity.

Table 4

Exam Lighting Veil ⁺ 15) Veil 5 *) Citl. 0.1 AND and 0.56 0.28 8.5 В and 0.53 0.25 8.8 AND b 0.56 0.28 2.9 В b 0.53 0.23 3.5

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*) Development time in minutes ·

Claims (3)

1 «Photographic silver halide emulsion» containing, as binder for silver halide, gelatin »especially gelatine-poor accompanying substances and containing an additive for sensitizing the emulsion during chemical maturation» characterized by »as said sensitisers containing asymmetric disulphides of the general formula (W) _a (X) _b A - S - S - V (X) _e (Z) _d , 2. wherein A represents a C 1 -C 6 alkyl group, a phenyl group or a benzyl group; a carboxyl group and / or a methoxycarbonyl or ethoxycarbonyl group; an amino group which may optionally be acetylated, methylated or ethylated and d denotes a number from 0 to 2, wherein a + d »or Ъ + e» has a value of 0 to 4 · A photographic emulsion of a noble metal or reducing sensitizer · Item 1 »characterized by» containing sensitizers based on 3. A photographic emulsion according to claim 1 or 2, characterized in that it contains asymmetric disulfide in an amount of 0.5 · 10 * ⁵ to 2 · 10 * 3 _øо у _{и per} mole of silver halide ·