DD281265A5 - GELATINE-CONTAINING COUPLER DISPERSES FOR PHOTOGRAPHIC SILVER HALOGENIDE MATERIALS - Google Patents

Abstract

The invention relates to gelatin-containing coupler dispersants for photographic silver halide materials. According to the invention, gelatin-containing coupler dispersants comprise a water-insoluble p-hydroxybenzoic acid alkyl ester in combination with an alkyl or arylsulfonate of the general formula {gelatin-containing coupler dispersants; photographic silver halide materials, water-insoluble p-hydroxybenzoic acid alkyl esters; alkyl sulfonate; arylsulfonate; Fungal growth; bacterial decomposition; Farbkupplerdispergat; Degree of conversion}

Description

Field of application of the invention

The invention relates to gelatin-containing coupler dispersants for use in photographic silver halide materials.

Characteristic of the known state of the art

Some components for photographic materials, e.g. certain classes of color couplers, clear coaters, antioxidants, leaning agents or substances for absorbing unwanted light have little or no water solubility and must therefore be added to the pouring solution dispersed in gelatin. In doing so, they are mixed with the addition of high-boiling solvents, such as bi or ticresyl phosphate, bi- or tributyl phthalate, e.g. according to US-PS 2322027, triphenyl phosphate, diethyllaurylamide or liquid benzoic acid ester ^ e.g. according to DE-OS 2629842, usually with the addition of a low-boiling auxiliary solvent and a wetting agent by mechanical means finely dispersed in aqueous gelatin solution. After removal of the auxiliary solvent and solidification, the resulting disperse is stored until used in the film production. Such dispersants are required to be photographically inert, i. H. do not reduce the sensitivity and do not increase the fog. Specifically coupler dispersants also require high reactivity and high color yield, i. That is, the dispersed coupler should react quickly and as completely as possible to the image dye, whereby hue or color unit may not be adversely affected by Dispergatherstellung or additions. Furthermore, a sufficient durability of the dispersants in storage is necessary. This storage stability is mainly limited by three factors.

a) coalescens, d. H. the coalescence of the dispersed droplets reduces the surface area and hence the reactivity and deteriorates graininess and sharpness; larger droplets can lead to wetting errors.

b) crystallization of dissolved in the oil droplets. Substances also significantly reduces the reactivity and leads to turbidity.

c) The biodegradation of gelatin by bacteria leads to the destruction of the gel structure and generates decomposition products. Similarly, fungal infestation makes gelatin gels useless.

However, conventional dispersants meet the requirements mentioned only partially. In particular, reactivity and color yield of the coupling dispersants leave something to be desired, so that a part of the dispersed coupler remains unused or couplers must always be used in excess in order to achieve the required photographic properties.

Furthermore, the storage stability of gelatin-containing dispersants is insufficient. Although many substances have been proposed to improve the resistance to bacterial and fungal attack, e.g. in EP 150517, JP 60119517 and JP 60119547. These substances are added as aqueous or alcoholic solutions. However, in contrast to silver halide emulsions in which the equilibrium silver ions already effectively inhibit the growth of bacteria and fungi, in coupler dispersions and similar gels, a substantially higher concentration of these actives is needed to provide adequate protection. This is problematic insofar as substances such as phenol, Raschit and particularly highly chlorinated phenols are toxic and cause problems both in the production and processing of photographic materials as well as an environmental impact when they enter the wastewater during photographic processing. Furthermore, high concentrations of these drugs are often not tolerated by the photographic system, resulting in problems with casting or drying of the material as well as the consistency of the photographic properties in the storage of the films or photographic papers. In part, the sensitivity or fog of the photographic materials are negatively affected. Although it is possible to increase the shelf life of the dispersants in the storage of the dispersants in cold storage or reduce the amount of substance necessary for protection something, but these measures are costly and limited in their effectiveness. Thus, coupler dispersants according to the prior art prove to be a compromise solution which can satisfy completely neither with regard to security of the storage nor with regard to the photographic properties.

OBJECT OF THE INVENTION The object of the invention is storage-stable gelatin-containing coupler dispersates for photographic silver halide materials.

Explanation of the essence of the invention

The object of the invention is to increase the resistance of gelatin-containing Kupplerdispergate against fungal growth and bacterial decomposition and the degree of conversion of couplers.

According to the invention the object is achieved in that gelatin coupler dispersants color coupler in combination with a water-insoluble p-hydroxybenzoic acid ester of the general formula

COOR

in the

R is alkyl having 3 to 12 carbon atoms, in an amount of 0.04 to 0.12 mmol prog gelatin and a compound of the general formula Il A SO ₃ ZII, in the

A is alkyl having at least 8 C atoms, phenyl, naphthyl and Z is Na, K, in an amount of 0.01 to 1 mmol per g of gelatin.

Compounds of the formula I and II can be prepared easily by known methods (p-hydroxybenzoic acid alkyl ester, see Beilstein's Handbook of Organic Chemistry, 4th ed., Third Supplementary Works, pp. 306 et seq., Fourth Supplementary Works, page 374 et seq., Substances of the general formula A) SO ₃ Z see, for example, Ullmanns Enzykl, d.techn. Chemie, 3rd ed., Vol.3, p.312 ff.). As a coupler, the usual hydrophobic couplers can be used.

The additives of the invention are dispersed together with the photographic components, wherein the usual hydrophobic oil-forming agents such as tricresyl phosphate or dibutyl phthalate z. B. in accordance with US Patent 2322027 used alone or in admixture with other dispersing additives. The dispersion can be carried out by the usual methods. Since the additives according to the invention remain relatively small in quantity relative to the amounts of coupler and oil-forming agent used, they can generally be dispersed in without increasing the amount of oil-forming agent. An advantage of the invention is that the storage stability of the gelatin-containing Kupplerdispergate invention is substantially improved. Although the bacteriostatic activity of p-hydroxybenzoic acid esters is known per se, however, the combination according to the invention with alkyl or arylsulfonates results in a substantial increase which was hitherto unknown.

According to Handbook of Antiseptics II / 2, Berlin 1983, p 121 and Szantho et al., Farmacia 19 (1971), pp. 115-121 surface-active substances weaken the inhibitory effect of p-hydroxybenzic acid esters. With the application of the combination according to the invention, which shows significant advantages, a prejudice is therefore eliminated. Another advantage of the invention is that the additives of the invention are toxicologically safe. The p-hydroxybenzoic acid esters are practically insoluble in water and remain in the photographic processing in the film or photographic paper, so that the dispersants of the invention are also advantageous from the viewpoint of environmental protection. Gelatin-containing coupler dispersants containing the combination of substances according to the invention can be stored for at least 6 months at room temperature without bacterial decomposition or fungal infestation occurring. Coalescence and crystallization in oil-dispersed color couplers are not caused by the substance combination according to the invention. An additional advantage of the invention is an improved degree of conversion of the coupler which manifests itself in an increase in color density per unit amount of coupler dispersant and results in higher gradation and maximum density as well as higher sensitivity of the photographic material prepared using the inventive dispersate. Since less color coupler is required to achieve the same maximum density than prior art dispersants, material costs are saved.

example 1

1.1. Preparation of Dispergate Dispergat 1 100 g of the magenta coupler of Structural Formula I.

LJ

VNH CO

Cl-, ^ ~ ^{Ί (l)}

are dissolved in a mixture of 40OmI ethyl acetate and 100 ml of tricresyl phosphate at 50 ⁰ C and dispersed at 6O ⁰ C in 1.2518% gelatin solution with the addition of a conventional wetting agent using a high-speed stirrer for 30 min. Then ethyl acetate is distilled off at 40 ^° C. under reduced pressure. There is obtained a stable dispersion having an average particle diameter of 0.22 цt.

Dispergate A1 contains no stabilizing additives.

In a completely analogous manner, the following dispersants are prepared, but have the following differences:

Dispergate B1 subsequently receives an addition of 9.5 mg = 0.1 mmol of phenol prog gelatin.

Dispergate C1 subsequently receives an addition of 14.5 mg & 0.1 mmol of Rashit (г-МеИіуІ-З-СЫогргіепоІ) per g of gelatin.

The dispersants B1 and C1 show the influence of preservatives according to the prior art.

Dispergate D1 contains 10 mg of 0.055 mmol p-hydroxybenzoic acid propyl ester per g of gelatin which was dispersed together with the coupler.

Dispertrate E1 contains 5 mg of 0.015 mmol of stearylsulfonate prog gelatin, co-dispersed with the coupler.

Dispersate F1 demonstrates the benefits of the invention and contains 10 mg = 0.055 mmol of propyl p-hydroxybenzoate per g of gelatin in combination with 5 mg = 0.015 mmol of sodium stearylsulfonate prog gelatin.

Both substances were dispersed in with the coupler.

1.2. Storage of the dispersates

Samples of the dispersants are diced and loose

a) in the refrigerator at + 5 ° ... + 8 ° C

b) at room temperature in closed bottles

kept. The bottles are opened and inspected weekly. The dispergate is classified as unusable as soon as the gel strength decreases so that the cubes deform. In addition, in these cases, a distinct smell occurs.

Table 1 Dispersion durability at room temperature in the refrigerator 3 weeks A1 8 weeks 6 weeks B1 15 weeks 11 weeks CI 32 weeks 21 weeks D1 49 weeks 4 weeks E1 10 weeks 40 weeks F1 > 18 months

1.3. Photographic exam

On a photographic not transparent film base, an emulsion layer is applied containing a green sensitized Chlorbromsilberemulsion in a 0.37 gag / m ² corresponding amount of Dispersion A1 in a 470mg = 0,85ттоІ / ^т г magenta coupler equivalent amount and customary wetting agents and curing agent. As a coating, a hardened gelatin layer of thickness 1.0 цt is applied.

The resulting material A is exposed behind a sensitometric gray wedge, developed according to ORWO specification 7182 and measured on a commercially available densitometer motor (x-Rite 310 TRX). The sensitometric test corresponds to TGL 8400/04.

In a completely analogous manner, the materials BF are produced and tested. They differ with regard to the dispersants used, but have the same silver and coupler order per m ² as material A.

Table 2 shows the results obtained. Material F made with dispersate according to the invention shows about 15% higher maximum density and correspondingly higher gradation.

Table 2 material Fri. _min Ei.o D _m .x gi 92 0.09 7Hz [Pez] A 0.08 0.11 13.6 2.35 1.56 2.30 B 0.09 0.12 13.8 2.40 1.57 2.30 C 0.07 0.11 13.6 2.43 1.59 2.26 D 0.08 0.11 13.8 1.35 - 1.55 2.28 e 0.07 0.10 13.4 2.28 1.40 2.26 F 0.10 14.0 2.71 1.73 2.65

7 Hz = values after artificial aging in an oven for 7 days at 5O ⁰ C, 30% rel. humidity

Example 2

100g pivaloylacetanilide (yellow couplers) are dissolved in a mixture of 200 ml ethyl acetate and 100 ml of tricresyl phosphate to 5O ⁰ C dispersed at 6O ⁰ C dissolved in 625ml 8% gelatin solution with addition of a conventional wetting agent by means Schnellrührwerk in 30min. After removal of the ethyl acetate, a stable dispersion having a mean particle diameter of

The additives of the dispersions A2-F2 produced according to this specification correspond to A1-F1 from Example 1.

In a storage test analogous to Example 1, the following durability is achieved:

Table 3 Dispersion durability at room temperature in the refrigerator 6 weeks A2 10 weeks 10 weeks B2 16 weeks 14 weeks C2 30 weeks 20 weeks D2 12 months 5 weeks E2 10 weeks 38 weeks F2 > 18 months

Example 3

100g of a cyan coupler of structural formula

OH

Cp

^C 18 ^H 37

Cl

are dissolved and dispersed in 100 ml of dibutyl phthalate as a high-boiling solvent analogous to Example 1. There is obtained a stable dispersion having a mean particle diameter of 0.16K. The additions of these dispersants A3-F3 correspond to A1-F1 from Example The following durabilities are achieved in a test analogous to Example 1:

Table 4 Dispersion durability at room temperature in the refrigerator 4 weeks A3 7 weeks 7 weeks B3 16 weeks 12 weeks C3 30 weeks 20 weeks D3 42 weeks 5 weeks E3 8 weeks 36 weeks F3 > 18 months

Claims (1)

Gelatin-containing coupler dispersants for photographic silver halide materials, characterized in that they contain color couplers in combination with a water-insoluble p-hydroxybenzoic acid ester of the general formula COOR in which R is alkyl having 3 to 12 C atoms, in an amount of 0.04 to 0.12 mmol per g of gelatin and a compound of the general formula II ASO3 ZII, in which A is alkyl having at least 8 C atoms, phenyl, Naphthyl and Z denote Na, K, in an amount of 0.01 to 1 mmol per g gelatin.