EP0071122B1 - Colour-photographic recording material - Google Patents

Description

The invention relates to a color photographic recording material with at least one silver halide emulsion layer and embedded color couplers, in which the color yield is increased by special additives and at the same time the color granularity is reduced.

High color yields in chromogenic development are generally very desirable. Color yield is understood to mean the ratio of maximum color density to silver halide application (given in g AgN0 ₃ per m ² ). With higher color yields, the required maximum densities are achieved with low silver deposits, which has an advantageous effect on sharpness and sensitivity.

Methods of increasing the color yield (ie to achieve the highest possible color densities with the lowest possible silver application) are known to the person skilled in the art: in principle, higher color yields are achieved by using a high ratio of coupler to silver halide in order to remove the developer oxidation product that occurs during color development as completely as possible To couple dye. Color couplers with a high coupling speed work in the same way. However, both methods have the disadvantage that, as a rule, the color granularity increases sharply with increasing color yield.

Smaller silver halide grains are known to provide higher color yields and lower color grains than large ones; however, the photographic sensitivity is lower for smaller silver halide grains.

US Pat. No. 4,207,393 describes substances by means of which the color yield can be increased. The effectiveness of these substances is comparatively low; furthermore, they do not reduce the color grain.

DE-A-2 049 689 discloses a method for emulsifying substances with the aid of succinic acid derivatives. DE-A-3 002 201 discloses recording materials which have succinic acid derivatives in a color coupler-containing layer for the introduction of hydrophilic color couplers.

The invention has for its object to provide a color photographic recording material with increased color yield and reduced color granularity, which contains hydrophobic color couplers.

worin bedeuten :

• R¹ eine geradkettige oder verzweigte, gesättigte oder ungesättigte aliphatische Gruppe mit mindestens 8, vorzugsweise 12 bis 18 C-Atomen,
• R² Wasserstoff oder Alkyl, z. B. -CH₃ oder C₂H₅,
• R³ eine über ein Ring-C-Atom oder über ein Ring-N-Atom angeknüpfte heterocyclische Gruppe, z. B. Furyl, Thienyl oder Morpholino, oder eine Gruppe der Formel ―(X)_n―R⁴,
• R⁴ eine Arylgruppe,
• X -0-, -NH-, -NCH₃- oder -CH = CH-,
• m 0, 1 oder 2,
• n 0 oder 1.

A color photographic recording material has now been found with at least one light-sensitive silver halide emulsion layer, which in this layer or associated with it contains at least one color coupler, the color coupler-containing layer having a succinic acid monoester and being an inner layer. According to the invention, all color couplers in this inner layer are hydrophobic and the succinic acid monoester corresponds to the following formula I.

in which mean:

• R ^{1 is} a straight-chain or branched, saturated or unsaturated aliphatic group with at least 8, preferably 12 to 18, carbon atoms,
• R ^{2 is} hydrogen or alkyl, e.g. B. -CH ₃ or C ₂ H ₅ ,
• R ^{3 is} a heterocyclic group attached via a ring C atom or via a ring N atom, e.g. B. furyl, thienyl or morpholino, or a group of the formula - (X) _n ―R ⁴ ,
• R ^{4 is} an aryl group,
• X -0-, -NH-, -NCH ₃ - or -CH = CH-,
• m 0, 1 or 2,
• n 0 or 1.

tragen, worin R¹, R², X, m, n die bereits angegebenen Bedeutungen haben, oder aber einen Substituenten der eine solche Gruppe enthält.The aryl group represented by R ⁴ is, for example, a phenyl group or a naphthyl group. These groups can be unsubstituted or carry further substituents, e.g. B. halogen, alkyl, alkoxy, acylamino, nitro, alkylsulfonyl, arylsulfonyl, cyan. In addition, the aryl groups represented by R ⁴ can be another group of the formula

wear in which R ¹ , R ² , X, m, n have the meanings already given, or a substituent which contains such a group.

• a) lange Ketten zur Mizellbildung mit dem Bindemittel (Gelatine),
• b) freie Carboxylgruppen zur Seifenbildung oder für eine gewisse Solubilisierungstendenz im alkalischen Bereich,
• c) Estergruppierungen mit benachbarten cyclischen Resten, die möglicherweise lösungsvermittelnde Wirkungen auf den Bildfarbstoff, den Leukofarbstoff oder den Farbkuppler ausüben.

The following structural features, which are present together in the compounds according to the invention, probably contribute to the described effect (increase in the color yield and reduction in the color granularity):

• a) long chains for micelle formation with the binder (gelatin),
• b) free carboxyl groups for soap formation or for a certain tendency towards solubilization in the alkaline range,
• c) ester groups with adjacent cyclic radicals, which may have solubilizing effects on the image dye, the leuco dye or the color coupler.

Examples of suitable compounds according to the present invention are given below (Table 1):

The radical R ³ given in the compounds 11, 12 and 13 is a symmetrical double-bonded radical to which two succinic acid monoester radicals with the meanings given in each case for R ¹ , R ² and m are bound.

The long-chain residues occurring in the listed compounds 1 to 21 are not clearly determined with regard to the degree of branching and, as far as unsaturated residues are concerned, with regard to the position of the double bond. Presumably these are mixtures of isomers.

The compounds used according to the invention are very easily accessible preparatively. They are produced from long-chain substituted succinic anhydrides which are reacted in a known manner with suitable hydroxy compounds. The succinic anhydride ring is opened to form a carboxyl group and an ester group. Products are formed side by side in which the long chain residue is in the position to the carboxyl group and those in which it is in the β position to the carboxyl group. For the sake of simplicity, only one form is represented in general formula I, which in this respect represents a simplified spelling.

Manufacturing instructions for compound 3

3520 g of octadecenylsuccinic anhydride, 1,080 g of benzyl alcohol and 20 g of DABCO (1,4-diazabicyclo [2,2,2] octane) were heated at 120 ° C. in a 10 1 four-necked flask equipped with a stirrer, thermometer and reflux condenser, for 3 hours. 4,600 g of diethyl carbonate were added to the highly viscous reaction mixture, which had cooled to 50 ° C., with stirring, a 50% solution in diethyl carbonate being obtained.

The other connections can be made in an analogous manner.

The compounds of the general formula can advantageously be used as oil formers in the preparation of color coupler emulsions, they being used either instead of or in a mixture with conventional hydrophobic oil formers such as tricresyl phosphate or dibutyl phthalate. B. according to US 2,322,027 or more or less hydrophilic oil formers z. B. according to DE-OS 1 772 192, DE-OS 2 042 659, DE-OS 2 049 689 can be used. Several of the compounds of the general formula I can also be used next to one another or in a mixture with one another. However, these compounds can also be emulsified in the absence of color couplers and the color coupler-free emulgate obtained in this way can be mixed with color coupler-containing emulsions or solutions. To produce the emulgate, the usual method is used, in which the substances to be emulsified, e.g. B. the color couplers and optionally other additives such as white couplers, UV stabilizers, antioxidants together with the compounds to be used according to the invention in a water-immiscible or only slightly miscible organic solvent and with the aid of an emulsifier in the ratio that the desired concentration of the substance to be incorporated corresponds to emulsified into the casting solution of the photographic layer, which contains in particular the binder and optionally other ingredients.

However, it is also possible first to produce an emulsifier and, if necessary, to store it temporarily, which is not identical to the actual casting solution, but which is only added at a later point in time. Suitable emulsifiers for this purpose are, for example, high-speed stirrers, so-called mixing sirens, ultraturrax devices and ultrasound devices. The compounds of general formula 1 are generally used in an amount of 0.05 to 5.0 parts, based on 1 part of color coupler; they are preferably used in amounts of 0.1 to 1.0 parts per 1 part of color coupler (parts by weight).

The color photographic recording material of the present invention contains at least one silver halide emulsion layer and at least one hydrophobic color coupler associated with this silver halide emulsion layer. The term “assigned” means that the spatial arrangement of the silver halide emulsion layer and color coupler is of such a type that an interaction is possible between them in the chromogenic development, which allows an image-like correspondence between the silver image formed and the image-like distribution of the chromogenically produced dye. For this purpose, the color coupler need not necessarily be contained in the light-sensitive silver halide emulsion layer; it can also be present in a non-photosensitive binder layer adjacent to the silver halide emulsion layer. As a rule, the color photographic recording material according to the invention even contains at least three silver halide emulsion layers with different spectral sensitivity and respectively assigned color couplers, whereby the relationship between the spectral sensitivity of the silver halide emulsion layer and the color of the dye produced from the assigned color coupler during chromogenic development is also addressed by "assigned . In general, the color of the image dye is complementary to the color of the light that is recorded in the associated silver halide emulsion layer. In certain cases, the color photographic recording material can also contain several silver halide emulsion layers of the same spectral sensitivity and possibly different general sensitivity ("speed"), whereby again several silver halide emulsion layers with the respectively assigned color couplers, either arranged according to their spectral sensitivity or according to their general sensitivity, can be combined to form layer units or layer units of different spectral sensitivity are generally separated from one another by non-light-sensitive intermediate layers in order to effectively prevent unwanted diffusion of developer oxidation products into layers (not (spectrally) assigned) containing color coupler. The intermediate layers can be pure binder layers or binder layers which contain further additives, e.g. B. Compounds that can react with diffusing developer oxidation products genes, filter dyes, curing agents, embedded developers, UV absorbers or (not light-sensitive) micrate emulsions.

The color photographic recording material according to the invention contains a compound of the general formula I in at least one inner layer containing a color coupler, ie. H. in a layer that is covered by at least one further layer. This inner layer can be any one or more of the light-sensitive silver halide emulsion layers or one or more of the non-light-sensitive color coupler-containing layers which are adjacent to a silver halide emulsion layer. The color couplers in this layer are couplers that are incorporated into casting solutions using oil formers. These are couplers that are soluble in organic solvents, especially in oil formers (so-called hydrophobic couplers).

However, it is also possible to use hydrophilic couplers in other layers, which can be incorporated together with oil formers, for example by a method such as is described in German patent application P 30 02 201.6. The couplers are 2, 4 or 6 equivalent color couplers (Research Disclosure 19 536 - July 1980). They are colorless or colored (mask couplers). In addition, other couplers can be used, e.g. B. white coupler or DIR coupler.

• a) bei Anwesenheit von Silberhalogenid weniger als 0,6 g, vorzugsweise weniger als 0,5 g Gelatine pro 1 g AgNO₃, bzw.
• b) bei Abwesenheit von Silberhalogenid, aber Anwesenheit von Farbkuppler weniger als 0,8 g, vorzugsweise weniger als 0,6 g Gelatine pro 1 g Farbkuppler enthalten.

With the aid of the compounds of the general formula I, not only is the color yield effectively improved, but at the same time the color granularity is considerably reduced. The increase in color yield and the reduction in color granularity are particularly pronounced when the compounds according to the invention are used in comparatively low-gelatin layers. This includes layers that

• a) in the presence of silver halide less than 0.6 g, preferably less than 0.5 g gelatin per 1 g AgNO ₃ , or
• b) in the absence of silver halide, but the presence of color couplers contain less than 0.8 g, preferably less than 0.6 g of gelatin per 1 g of color coupler.

The color photographic recording material according to the invention is equally suitable for the production of color negatives and for the reversal process.

example 1 Emulgate containing color couplers 1.1 Manufacturing the Emulgate

As described below using the example of compound 3, the invention was carried out using the Connections made with Emulgate containing color couplers. A compound of the following formula was used as the color coupler:

A solution of 5 g of compound 3 and 1.33 g of sodium dodecylbenzenesulfonic acid (75% strength) in 15 g of ethyl acetate was emulsified in 400 g of a 5% strength aqueous gelatin solution (50 ° C.) in 15 g of ethyl acetate (first stage). After the addition had ended, the mixture was stirred for a further 3 min and then a coupler solution of 100 g of color coupler and 30 g of compound 3 was emulsified in 200 g of ethyl acetate (second stage). Ethyl acetate was then largely evaporated.

The amount of the oil former emulsified together with the color coupler (second stage) is between 10 and 150%, based on the amount of the coupler, preferably between 20 and 70%.

1.2 Preparation of the casting solution

1 part of a red-sensitized silver bromide iodide emulsion with 6 mol% iodide, which contained 200 g of AgNO ₃ , equivalent amount of silver halide and 30 g of gelatin per kg, was mixed with 1 part of the according to 1.1. prepared emulsifier and 2 parts of water mixed (parts by weight).

1.3. Production of a photosensitive material and processing

The after 1.2. The casting solution produced was poured onto a layer support (silver application: 2 g AgNO ₃ per m ² ), hardened, exposed behind a gradient wedge and processed according to a color negative process, which is described in "The British Journal of Photography", 1974, pages 597 and 598 is. The following table 2 shows the color yields determined at D _max (measured behind the red filter) and for the densities D = 0.5; D = 1.0; D = 1.5 the measured color granularity values σ _{D are} compiled. For the determination of the (color) granularity, reference is made to TH James, The Theory of the Photographic Process, 4th ed., Macmillan Publ. Co., Inc., New York / London 1977, pp. 618-621.

Example 2 Colored coupler-free concentrated admixture gate 2.1. Production of the Emulgate

The example of compound 3 below describes how concentrated coupler-free admixture gates were produced from the compounds according to the invention.

To 10 l of a 10% gelatin solution (50 ° C.) was added 0.5 kg of a 10% aqueous solution of sodium disec.-butylnaphthalenesulfonic acid, and then a solution of 4 kg of compound 3 in 4 kg was mixed with a high-speed siren Diethyl carbonate emulsified. After the auxiliary solvent had been evaporated off, a highly concentrated admixture was obtained with a content of 270 g of compound 3 per kg of emulsate, which can be added to an emulsion in addition to the color coupler emulsate.

2.2. Preparation of the casting solution

sowie 55 g Dibutylphthalat und 37 g Gelatine enthielt. Weiter hinzugefügt wurden 0,1 Teile des unter 2.1. beschriebenen Zumischemulgats und 0,4 Teile Wasser (Gewichtsteile).1 part of a green-sensitized silver bromide iodide emulsion with 6 mol% iodide, which contained 200 g of AgNO ₃ equivalent amount of silver halide and 30 g of gelatin per kg, was mixed with 0.5 part of an emulsifier containing 185 g of a coupler per kg formula

and 55 g of dibutyl phthalate and 37 g of gelatin. 0.1 parts of the item 2.1. described admixture and 0.4 parts water (parts by weight).

2.3. Production of a photosensitive material and processing

The after 2.2. The casting solution prepared was poured onto a layer support with a silver coating of 2 g AgNO ₃ per m ² , hardened, exposed behind a gradient wedge and subjected to the following color-Umkerverarbeitung:

Black and white development:

6 min at 30 ° C in a developer consisting of:

Stop bath:

5 min in a solution

Intermediate watering: 10 min Diffuse reverse exposure: 2 min

Zwischenwässerung : 10 min Bleichbad : 5 min in einem Bleichbad bestehend aus

mit Wasser auf 100 ml aufgefüllt und mit Essigsäure auf pH = 5,2 eingestellt.

• Zwischenwässerung : 5 min
• Fixierung : 5 min in einem Fixierbad bestehend aus :

mit Wasser auf 1 000 ml aufgefüllt, pH = 7.
Schlußwässerung : 5 min

Color development: 6 min in a color developer
consisting of :

Intermediate rinsing: 10 min bleach bath: 5 min in a bleach bath consisting of

made up to 100 ml with water and adjusted to pH = 5.2 with acetic acid.

• Intermediate watering: 5 min
• Fixation: 5 minutes in a fixing bath consisting of:

made up to 1000 ml with water, pH = 7.
Final watering: 5 min

Claims (4)

1. Colour photographic recording material which comprises at least one light-sensitive silver halide emulsion layer and contains in this layer or associated therewith, at least one colour coupler, wherein the colour-coupler-containing layer contains a succinic acid monoester and is an internal layer, characterised in that, in this internal layer, all of the colour couplers are hydrophobic and the succinic acid monoester corresponds to the following formula I

wherein

R¹ denotes a straight-chain or branched, saturated or unsaturated aliphatic group with at least 8 C atoms,

R² denotes hydrogen or alkyl,

R³ denotes a heterocyclic group attached via a ring C atom or via a ring N atom or a group of the formuia ―(X)_n―R⁴,

R₄ denotes an aryl group,

X denotes -0-, -NH-, -NCH₃- or -CH = CH-,

m denotes 0, 1 or 2, and

n denotes 0 or 1.

2. Recording material according to Claim 1, characterised in that the internal layer contains an additional oil former for the hydrophobic colour coupler.

3. Recording material according to Claim 1, characterised in that the compound of the general formula I is contained in a silver halide emulsion layer which contains less than 0.6 g of gelatine based on the quantity of silver halide corresponding to 1 g of AgNOg.

4. Recording material according to Claim 1, characterised in that the compound of the general formula I is contained in a silver-halide-free binder layer which contains less than 0.8 g of gelatine based on 1 g of the colour coupler contained therein.