CS251619B1 - A method of producing black-and-white or chromogenic-induced negative photographic materials - Google Patents

Abstract

The solution relates to a method for preparing highly sensitive photographic negative materials consisting of 2 or more layers of different sensitivities. The less sensitive layer is prepared by mixing 2 separately prepared dispersions. The more sensitive layer is prepared from a bromo-iodosilver dispersion with a halide particle size of 0.7 to 1.3 µm, depending on the desired sensitivity. The Ag contents in the layers are determined according to the desired sensitivity, the steepness of the individual dispersions, the primary grain sizes and the use of a developing activator. The resulting material is sensitized either panchromatically or to the far panchromacy region.

Description

The invention relates to highly sensitive silver halide dispersions for photographic, black-and-white or chromogenically developed negative materials with sensitivities of 24 to 31 ČSN and a method of their preparation.

In photographic dispersions for the preparation of film and photographic negative materials, both black and white and color, increasingly higher sensitivity is required. Negative materials with a sensitivity of 27 ČSN and higher, sufficiently fine-grained, are becoming increasingly important. To achieve higher sensitivities, a number of production processes have been developed, consisting in the creation of silver halide particles containing various ratios of silver halides, i.e. silver chlorides, bromides and iodides dispersed in a protective colloid, e.g. gelatin or various polymeric substances.

The method of preparation of such dispersions leads to the formation of very large particles of silver halides in an attempt to increase sensitivity. Such dispersions are without exception based on mixed bromide and silver iodide with an iodide content of 1 to 15 mol .96. Silver halide dispersions for the preparation of panchromatic black and white and monochrome materials with a sensitivity of 24 to 31 ČSN require an average particle diameter of the mixed silver halide 3 = 0.7 to 1.3 / μm, in the case of planar crystal types, even higher sizes.

Such dispersions have a high particle size dispersion coefficient. An increase in the size of the primary halide grains leads to a disproportionate increase in the graininess of the developed image S„, a sharp decrease in the value of the maximum optical density D _mg|X , a decrease in the steepness, a decrease in the linear part of the characteristic curve and a decrease in the resolving power.

To improve the sensitometric properties of highly sensitive dispersions, simple mixing of stabilized dispersions can no longer be used. Such mixing leads to a decrease in the sensitivity of the more sensitive dispersion due to competition between the sensitivity centers of the mixed dispersions.

To achieve high sensitivity while maintaining low grain size and satisfactory sensitometric parameters, it is necessary to use the sum of the positive properties of a highly sensitive bromo-silver iododispersion with a large primary grain size and the positive influence of a lower sensitive chlorobromo-silver iododispersion, i.e. high maximum optical density, small grain size and higher steepness, without mutual influence.

The only method for solving this problem is multilayer dispersion coating, where the individual dispersions are arranged according to sensitivity when coating onto the substrate. This method is known for specific photographic negative and positive color and black and white materials and described in a number of patent documents such as US 4 124 876, DE 2 718 548 and DE 2 003 993· z*

The preparation of highly sensitive photographic negative materials according to these patents and the described procedures is difficult to solve, does not correspond to the required sensitivities and the ratios of individual dispersion coatings given in the patents do not provide satisfactory results. The patent literature of multilayer dispersion coatings is focused mainly on color negative materials with dispersions not suitable for the black and white process.

A series of photographic light-sensitive mixed silver halide dispersions in gelatin have now been prepared, different from the dispersions described in the above-mentioned patents and suitable, due to their properties, for multi-layer coating of dispersions for the production of highly sensitive photographic black-and-white or chromogenically developed negative films, with a relatively low grain size of the developed silver, an exceptionally high maximum optical density, fast development kinetics and a long straight-line portion of the characteristic curve and with a reduced silver content per area compared to commonly produced black-and-white negative materials. The newly prepared dispersions can be prepared by conventional casting techniques, i.e. single-jet casting, or even double-jet casting.

As solvents for silver halides, necessary in the precipitation process to achieve the required microcrystal sizes and thus sensitivity, it is possible to use thiocyanates, excess bromide of an electrolytic metal, and thioethers, which are described in US patent 3,574,628.

DE 2 824 249 or DE 2 921 817 e.g. 1,8-dihydroxy~3,6-dithiaoctane and longer, methionine and ethio' ··. in nin as described e.g. in patent DE 2 744 308 alkylcysteines with thioester derivatives as described in patent DE 2 614 862 or DE 2 938 535 and imicazoles or thiazoles as described in patent DE 2 758 7,1, preferably however ammonia.

The removal of the salts formed and the excess alkali metal bromide can be carried out by classical washing in the form of a gel in the cold or by decantation with distilled water after separation of the solid phase of silver halides using a flocculant. As flocculants, anionic polymers can be used, e.g. polystyrenesulfonic acid and sulfonated styrene copolymers as disclosed in patent DE J 085 422, anionic surfactants, inorganic salts of aphthalyl derivatives of gelatin, as disclosed, e.g., in patents US 2,614,928, 2,614,929 and 2,728,662.

As a protective colloid, for example, gelatin, polymeric substances of natural origin such as albumin, agar, gum arabic, gelatin derivatives such as acetyl gelatin, phthalyl derivative, dextransein, hydrophilic cellulose polymers and cellulose esters can be used, as disclosed in patent documents US 2,327,808, 2,448,534, 3,563,791, 2,311,086, 2,322,085, 2,6.4,928,

614,929, 2,614,930, 2,614,931, 2,748,022, 2,787,545, 2,816,027, 2,956,880, 3,061,436,

132,945, 3,138,461, 3,157,906, 3,184,312, 3,227,571, 3,436,220, 3,551,151, 3,532,502,

539,353, 3,923,517, and 4,018,609, synthetic polymers such as acrylamide polymers, polyvinyl alcohols and their derivatives, polyvinyl acetals, alkylated and sulfoalkylated acrylates and methacrylates, polyvinylpyrrolidones, polyvinylpyridines, maleic acid copolymers, vinylamine copolymers, polyalkylene imines and their copolymers, and vinylimidazoles, as are

listed in patents US files 2,253,078, , 2,484,456, 2,414 207, 2 541 474, 2 632 704 2,579,016, 2,632,704, 2,698,240, 2,533,166, , 2,495,918, 2,565 418, 2 860 986, 2 860 428 2,893,867, 2,904,539, 3,003,879, 3,167,430, , 3,284,207, 2,957 767, 2 904 539, 3 419 397 3,479,186, 3,392,025, 3,511,818, 3,679,425, 3706 564, 3,415 653, 3 615 624, 3 681 079 3,721,565, 3,852,073, 3,861,918, 3,813,251 , and 3,939,130.

The dispersions of the invention can be chemically sensitized with conventional chemical sensitizers containing sulfur, selenium or tellurium, such as active gelatin, thiosulfate, allyl isothiocyanate, thiourea, thioacetamide, S-alkylthiourea, allylselenourea, allyltellurourea, colloidal selenium and reducing agents such as stannous chloride, aminomethanesulfinic acids polyamines and thiourea dioxide as disclosed in U.S. Patents 1,623,499, 2,399,083, 3,297,447, 3,189,458, 3,501,313, 2,518,689 and 2,923,610.

They can also be chemically sensitized with platinum group metals, such as gold, palladium, iridium, rhodium, ruthenium, platinum, in the form of salts and inorganic or organic complexes of these metals, as disclosed in US Patents 2,399,083, 2,448,060,

540,086 and 3,367,778 and publications by E. Koslowski Z. Wiss Photogr. Photophys. Photochem.

65-72 (1951). The process of chemical sensitization is intended to create sufficiently large centers of sensitivity and thereby substantially increase dispersion.

After the chemical sensitization is complete, the process must be stopped and stabilized against fogging during the aging process. Conventional stabilizers can be used to stabilize the dispersions. Spectral sensitizers, hardeners, development activators, and wetting agents can also be used in a similar manner as described in U.S. Patents 2,399,083, 2,448,060, 2,540,086, and 3,367,778.

The method of preparing extremely sensitive silver halide dispersions for photographic negative materials with a sensitivity of 24 to 31 ⁰ ČSN according to the invention consists in preparing a photographic dispersion with a sensitivity of 18 to 22 ČSN, which is the basis of the first coating. This dispersion has a low graininess of the developed image _ θ g = 10 - 22.10“^ with a high value of maximum optical density.

25,619

According to the invention, for the resulting photographic negative materials with a sensitivity of 24 to 26 ČSN, it is necessary to achieve in the first coating with a dispersion of sensitivity of 18 to 21 ČSN at a silver content on the surface in the first layer of 2 to 3 g/m ² , i.e. in such a way as to ensure a sufficient number of microcrystals with a low primary grain size and low sensitivity for areas of optical densities higher than 1. The maximum optical density achieved by this dispersion in the first layer must be D _m0x = 1.3 to 2. The slope of this dispersion must be at least the same or higher than the slope of the higher-sensitivity dispersion.

For photographic materials with a sensitivity above 28 ČSN, the silver halide dispersion for the first layer must have a sensitivity of 20 to 22 ČSN with a silver content per area of 2.3 to 3.5 g/m ² . The maximum optical density of this layer must be D _msx = 1.2 to 2. The particle size of the silver halide must be 3 = 0.4 to 0.7 μm. The preparation of such dispersions is described in the above-mentioned patents.

For the first coating, the best suited are mixed silver halide dispersions based on chlorine _- bromine silver iodide/ which are prepared by mixing two basic dispersions as follows. A typical dispersion of the first layer is shown in Fig. 1 (microcrystal images were obtained on a Tesla BS 200 electron microscope at 20,000 times magnification). Fig. 2 shows the different sizes of silver halide microcrystals of a typical mixed dispersion I.

The dispersion with higher sensitivity, i.e. the dispersion for the second layer coating, must meet the following requirements:

- the Ag/m content in the second layer must correspond to the required sensitivity at the dB dimension of the microcrystals and the achieved steepness of the first layer.

- the steepness of the second layer is regulated by the dispersion's own steepness, the dispersion coefficient of the particle size distribution, the Ag/m content and the use of the development activator. The steepness of the second layer must not be higher than the steepness of the first layer.

- the size of the primary grain of the dispersion of the II. layer must lie in the range 3 - 0.7 to 1.3 µm, depending on the required sensitivity of the resulting photographic material.

- the dispersion for the second layer must be based on silver bromide-iodide.

Silver contents for individual layers of photographic material and required sensitivity

I. layers can be calculated or graphically determined from the characteristic curves of individual dispersions obtained from monolayers with a defined Ag/m content. If the 2 Ag/m contents are not sufficiently matched with the sensitivity and slope for the individual layers, breaks or delays occur on the characteristic curve of the resulting photographic material.

Fig. 3a) shows the correct alignment of both layers. The I. layer is noticeably steeper here with a higher D_„„ . In Fig. 3b) there is a clear delay on the sum characteristic curve due to sensitivity mismatch. Fig. 3c) and 3d) show the misalignment of both layers due to incorrect Ag/m content or due to sensitivity mismatch, e.g. higher sensitivity in the I. layer.

For dispersions for the coating of the second layer, only dispersions based on mixed silver halide bromide-silver iodide in a molar ratio of 85 to 99.5 : 0.5 to 15 are suitable according to the invention. The required size of silver halide microcrystals can be regulated by the time of the silver nitrate solution flowing into the aqueous gelatin solution of the halide mixture/the length of Ostwald ripening in an ammonia environment/the process temperature in the range of 40 to 70 °C and the concentration of the solutions used in the precipitation phase. The variation coefficient can be regulated by dividing the AgNO^ solution into several parts, the amount of iodide and the length of Ostwald ripening.

A typical dispersion for the coating of the second layer of negative materials with a sensitivity of 27 ČSN is shown in Fig. 2, obtained using a Tesla BS 200 electron microscope. Magnification 20 OOOx. Such dispersions are prepared according to the invention by the classical single-jet method. After the precipitation is complete, excess salts can be removed by washing with cold in noodles or by using the solid phase separation method, where flocculation is preferably carried out with an N-phenylcarbamoyl derivative of gelatin.

Flocculation of the dispersion takes place in the pH range of 4.5 to 5.5. The separated mixed silver halide is redispersed before chemical sensitization in gelatin. The dispersion is then adjusted after washing to a pBr value of 2.5 to 3.2 and pH 6 to 7 by chemical maturation in the presence of active gelatin containing sodium thiosulfate pentahydrate in an amount of 3 to 15 mg/mol Ag, a gold complex formed from 3 to 15 mg gold chloride/mol Ag and ammonium thiooxynate in an amount of 50 to 150 mg/mol Ag, disodium salt of diaminotetraacetic acid, sodium toluenesulfinate and sucrose.

Chemical sensitization takes place at a temperature of 48 to 55 °C and after its completion, it is necessary to dose stabilizers, namely 5-methyl-7-hydroxy-tetraazaindem and 2-amino-5-mercaptothiadiazole in an amount of 500 to 2,000 mg, or 1 to 3 mg/mol Ag. The Ag/kg dispersion content varies depending on the type of preparation and ranges from 0.3 to 1 mol/kg dispersion, the binder content is 7 to 9%.

The average size of the diameter of the AgHal microcrystals of the II. layer of the photographic material with a sensitivity of 27 ČSN is 0.83 to 1.05 tons, the coefficient of variation /P= 15 to 50%, preferably 20 to 30%. The size distribution curve of the microcrystal dispersion of the II. layer is shown in Fig. 4.

* 2

In the case of a double coating of dispersions, namely a typical dispersion with an Ag content of 2.85 g/m (dispersion from Figure 1) with a mean size of 0.55 µm and a coefficient of variation of 23.5% and a typical dispersion II with a silver content per area of 3.4 g (dispersions from Figures 4 and 5) with a mean microcrystal size _of 0.90 µm and a coefficient of ^variation of 25%), the resulting photographic material has the size distribution of silver halide microcrystals given by the curve from Figure 4).

The average size of the microcrystals of the resulting negative material is 0.72 µm with a coefficient of variation /5^ ⁼ 27.5%. The grain morphology is represented by Fig. 5), obtained using an electron microscope at a magnification of 20,000x.

The described method of preparing light-sensitive silver halide negative photographic materials allows for a reduction in silver on the film surface while improving sensitometric properties and microsensitometric parameters.

Before coating, the dispersion must be spectrally sensitized. For sensitizing dispersions according to our invention, a combination of spectral sensitizers I to VI in an amount of 30 to 80 mg/mol Ag sensitizers I, 45 to 70 mg/mol Ag sensitizers II can be advantageously used.

to 100 mg/mol Ag sensitizer III or a combination of 30 to 70 mg/mol Ag sensitizer IV, 40 to 80 mg/mol Ag sensitizer V and 40 to 100 mg/mol Ag sensitizer VI.

III

(ch ₂ ) ₂ cooh

(ch ₂ ) ₃ sat ₃ (ch ₂ ) ₃ sat ₃ h

II

IV

(CH ₂ ) ₃ SOg (CH ₂ ) ₃ SO ₃ Na (ch ₂ ) ₃ so ₃ (ch ₂ ) ₃ so ₃ h

VI

(ch ₂ ) ₃ sat ₃

The exact amount of sensitizers depends on the specific surface area of the dispersion. Fig. 5 shows the spectrogram of the resulting film b with a combination of sensitizers I to III. Fig. 6 shows the spectrogram of the resulting negative film with a combination of sensitizers I to III (Fig. 6a) and IV to VI (Fig. 6b). Before coating, it is necessary to add a hardener solution, preferably a 5% solution of 2-hydroxy-4,6-dichloro-1,3,5-triazine in an amount of 2.5 to 12 mg/lg of binder.

For accelerated development and increased sensitivity, it is necessary to dose the condensate of stearylamine with polyethylene glycol C^H^^N/(C ₂ H^0)H ₂ c./ ₂ in an amount of 0.3 sž 1 g/mol Ag. To improve the coating properties, a suitable combination of surfactants is added.

Example 1

Preparation of dispersion Ie: 24.1 ml of distilled water, 4.24 g KBr, 0.52 g IfeCl, 0.14 g KJ and 0.6 g inert gelatin are left to swell for 20 minutes at 20 °C; and at a temperature of 60 °C the gelatin is dissolved. Two solutions of silver nitrate are added to this solution in turn: 1. a solution of 3.4 g AgNO^ in 35 ml of distilled water and 2. a solution of 2.26 g AgNO^ in 21 ml of distilled water.

The solutions are merged gradually so that the average diameter of the silver halide microcrystals is 3 = 0.34 µm and the coefficient of variation is 10.6%. Then the dispersion was washed in gel form, the pBr was adjusted to 3.2 (pAg = 8.4) and chemical sensitizers were added: sodium thiosulfate pentahydrate in active gelatin in an amount of 0.25 mg, a gold complex prepared from 0.23 mg of gold chloride and 3.38 mg of ammonium thiocyanate and 55 mg of sodium toluenesulfinate.

110 mg of phenol in 0.61 ml of ethanol is added as a preservative. Chemical sensitization lasts 150 minutes at a temperature of 52 °C. 45 mg of 5-methyl-7-hydroxy-tetraazaindene was added to stabilize the emulsion. The silver content in the emulsion was 3.2 g/100 g of dispersion, the binder content was 6.7%.

Preparation of dispersion lb: 27.7 ml of distilled water, 4.43 g of KBr, 0.22 g of KJ and 0.55 g of internal gelatin are allowed to swell for 20 minutes at 20 °C. At a temperature of 60 °C, the gelatin dissolves. The solution is heated to the desired temperature and a solution of 55.4 ml of distilled water and 5.54 AgNO^ is added, which was divided into two equivalent parts so as to achieve a mean size of the silver halide particle diameter of 3 = 0.658 µm and a coefficient of variation of 20.8%.

Then the cooled dispersion is washed with distilled water and after adding active gelatin, Br is adjusted to 3.3 (pAg = 8.4) and chemical sensitizers are added:

0.210 mg of sodium thiosulfonate pentahydrate, a gold complex prepared from 0.134 mg of gold chloride and 2.77 mg of ammonium thiocyanate and 54 mg of sodium toluenesulfinate. The dispersion was subjected to chemical sensitization at 52°C for 150 minutes.

As a preservative, 100 mg of phenol in 0.4 ml of ethanol was added, to suppress haze caused by heavy metals, disodium salt of diaminotetraacetic acid was added in an amount of 63 mg. After completion of chemical sensitization, the dispersion was stabilized with 40 mg of 5-methyl-7-hydroxytetraazainuene. The silver content was 3.15 g Ag/100 g of dispersion, the binder content was 8%. The dispersions Ia and Ib prepared in this way are mixed after completion of chemical sensitization and stabilization.

100 mg of dispersion prepared by mixing 25 g of dispersion Ia and 75 g of dispersion Ib are melted, heated to 42 °C and 1.98 mg of panchromatic sensitizer I, dissolved in a phenol-ethanol-water mixture, 1.4 mg of orthochromatic sensitizer II and 1.69 mg of orthochromatic sensitizer III, both also in a solution of the said mixture, are added.

To the dispersion was added 35 mg of 2-hydroxy-4,5-dichloro-1,3,5-triazine in the form of a 5% solution, 0.25 ml of a 10% solution of dialkyl sulfosuccinate (wetting agent) and 0.125 ml of a 10% solution of surfactant. The dispersion for the I layer was coated on a triacetate substrate with a final Ag content of 2.75 g/m .

Preparation of dispersion II:

ml of distilled water, 4.73 g KBr, 1.25 g NH^Br, 0.375 g KJ and 0.5 g internal gelatin are allowed to swell for 20 minutes at 20 °C and the gelatin is dissolved at a temperature of 60 °C. »

The temperature of the solution is adjusted to the desired value (40 to 75 °C) and then solutions of 3.24 g AgNO in 12.5 ml water and 0.24 ml ammonium nitrate solution (50%) and a solution of 6.36 g silver nitrate in 25 ml water and 0.12 ml ammonium nitrate solution (50%), together with 9.6 ml 11.8 N ammonia solution, are gradually added.

Precipitation and Ostwald ripening were carried out so that the average size of the silver halide microcrystals was 3 = 0.90 /um and the coefficient of variation was 25%. Then the dispersion was classically washed in cold form in the form of a gel and after adding active gelatin the pH was adjusted to 6.8 and pBr to 2.5 and in the presence of chemical sensitizers, 0.5 mg of sodium thiosulfate pentahydrate, 1.2 mg of gold chloride, 22.5 mg of ammonium thiocyanate, 245 mg of sodium toluenesulfinate, 2,440 mg of sucrose the dispersion was subjected to chemical sensitization at a temperature of 52 °C for 140 minutes.

To counteract the destructive effects of bacteria, 120 mg of phenol was added, and to suppress the negative effects of heavy metals, 24.5 mg of disodium salt of disminotetraacetic acid was added. The dispersion was stabilized with 50 mg of 5-hydroxy-7-methyltetraazadiene.

0.11 mg of 2-amino and 5-mercapto-thiadiazole.

The Ag content/100 g of dispersion was 53.7 g, the coating content was 7.5%. Before coating, 100 g of dispersion was melted, heated to 42% and spectral sensitizer I in the amount of 2.27 mg, spectral sensitizer II in the amount of 1.81 mg, spectral sensitizer XII in the amount of 2.72 mg, more 0.95 ml of a 5% solution of 2-hydroxy-4,6-dichloro-1,3,5-triazine in the form of the sodium salt, 0.3 ml of a 10% solution of the substance H-j^C^N/CCgH^OJggH/g, 0.24 ml of dialkyl sulfosuccinate in the form of a 10% solution and 0.12 ml of a 10% solution of a wetting agent were gradually added.

Coating A was performed on a triacetate substrate which had already been coated with a dispersion coating with an Ag/m content for dispersion II of 3.4 mg. A gelatin protective layer of the usual composition was applied to this coating. Coating A was evaluated sensitometrically after exposure to ns

FSR-41 sensitometer, exposure time 1/20 s and after development in the developer about the composition 4 - aminophenol sulfate 0.5g Sodium sulfite anhydrous 40g Hydroquinone 1g Sodium carbonate anhydrous 1.5 grams Sodium bicarbonate 1g Potassium bromide 0.2g Distilled water to 1 liter

t

851619

The induced melt was stabilized with a stabilizer with the following composition:

Sodium thiosulfate kryat. 250 g

Acetic acid concentrated 25 ml

Distilled water up to 1 liter

The following table shows the obtained sensitometric and microsensitometric values in comparison with the standard material (Fomapan N with sensitivity 27 ⁰ ČSN)

Table 1

2 Total Ag/m ^D o o ^{Dmax With} 0.1 D ^vol. ^á D = 0.8.10 ^-3 frosting A 6.15 0.10 2.55 28.0 0.3 480 seconds 28.8 standard material 3.1 0.17 2.15 26.8 0.3 550 seconds 33.2

D _oq is the inherent dispersion veil after subtracting the optical density of the substrate ³ max is the maximum optical density of the developed material

D difference in optical densities of a point 0.1 above the veil and a distance of 1.3 log. exposures on the exposure axis. Normalized values of slope

S _A . sensitivity values in ⁰ ČSN °3 = 0.8.10 ^J grain size value (fluctuation of optical densities) obtained on a granulometer '.SAMPLE for optical density 0.8.

Τ _γθ1 is the retrieval time required to reach the value 3 = 0.3 for the given retrieval type.

Coating A also shows better stability in the aging process compared to the standard coating. The following table shows the measured values for the aging of the material. The material was stored for 5 days at a temperature of 50 °C and a relative humidity of 80%.

Table 2

3 00 0 mex 3 with 0.1 m ‘‘‘vol. t. t.layers glaze A standard 0.12 0.2> 2.5-0 2.1 0.3 0.3 27.5 26.0 5-00 sec. 080 sec. 100 °C 70 °C

Example 2

Both silver halide dispersions I and II were prepared analogously to example 1. The additives, spectral sensitizers, wetting agents and hardeners correspond to the amounts given in example 1 ¹ 2 for coatings a. Coating B was produced with a silver content per area of 2.5 g/m for dispersion I and II.

3.0 g Ag/m for dispersion II. The thickness and composition of the protective layer were identical for coatings A and B. The following table shows the measured values compared to the standard material.

Table 3

0 total Ag/m ^D o o ^max D ^With 0.1 ^vol. ^With D = 0.8.10 ^-3 icing 5.5 0.11 2.21 0.8 27.7 510 seconds 26.9 standard 3.1 0.17 2.15 0.8 26.8 550 seconds 33.2

Example 3 \

The precipitation is identical to Example 1. However, instead of internal gelatin, an identical amount of N-phenylcarbamoyl-derivative of gelatin was used in the precipitation and after the precipitation was completed, after the particles of the three basic dispersions were reached 3 = 0.33 (Ia), 0.685 (lb) and 0.90 (II), the pH was adjusted to 3.5 for dispersion Ia, 4.0 for dispersion lb and 5.0 for dispersion II.

This resulted in flocculation of the silver hydrogen microcrystals in all dispersions, which were washed with distilled water and redispersed back into gelatin. The redispersion was carried out as in Example 1. Dispersions la, lb were adjusted to a content of 60 g Ag/kg and dispersion II to a content of 65 g Ag/kg. The binder content in la and lb was 6% and dispersion II was 8%. The further procedure was the same as in Example 1.

The coating was carried out for dispersion I at 2.5 g, for dispersion II at 3.0 g. The protective gelatin layer was identical to example 1. The following table shows the measured sensitometric values for coating C.

Table 4

Ag/kg ^D o o D max αΏ ^With 0.1 Col. frosting C 5.5 0.12 2.2L· 0.8 28.1 280 seconds

Example 4

Both silver halide dispersions I and II were prepared in the same way as in Example 1. The additives, i.e. spectral sensitizers, wetting agents and hardeners in dispersion II are identical. In dispersion I, an oleylamine condensate with polyethylene oxide CJ gH^N/CCgH,-0 )^ ₀ H/2 was additionally added in an amount of 20 mg per 100 g of mixed dispersion I,

Dispersion coating I Coating and composition of ochre sensitometric 2 was performed at 2.75 g Ag/m , the nth layer was identical to the example values obtained from the D coating at ice cream 1 . away o dispersion II to 3.4 g Ag/m'". The following table shows the measurement according to example 1. Table 5 in g/m ² D D oo max D ^with 0, ) 1 Col. ^S D = 0.8.10- frosting D 6.1 5 0.10 2.64 0.8 28.2 460 seconds 29.0 P h o r k 5th grade

Mixed silver halide dispersion I was prepared in the same way as in Example 1. However, the mixing ratio of the partial dispersions Io and lb was chosen to be 0.25:1. After chemical maturation and the usual stabilization, heating of the dispersion to a temperature of 42 °C, the following was added:

spectral sensitizer VI 3 mg spectral sensitizer IV 2.5 mg spectral sensitizer V 2 mg

2-hydroxy-4,6-dichloro-1,3,5-trisine 0.7 ml (5% solution) dialkylsulfo-sennare (10% solution) 0.25 ml surfactant (10% solution) 0.125 ml oleylamine condensate with polyethylene oxide (10% solution) 0.2 ml

Dispersion II was prepared analogously to Example 1, only during precipitation the amount of iodide was reduced to 2.2 mol % and the addition of silver solutions and Ostweld ripening in ammonia were chosen so that the resulting mean diameter of the silver halide microcrystals was d = 1.30 /ic and the coefficient of variation was 35%.

After chemical sensitization, carried out according to Example 1 and after stabilization also described in Example 1, the Ag/m ² content was 53 g and the binder 9%, the dispersion temperature was adjusted to 42 °C and 2.5 mg of spectral sensitizer Iv, 3 mg of spectral sensitizer V, and 3 mg of spectral sensitizer VI, 1 ml of a 5% solution of 2-hydroxy-4,6-dicfclor251619 were added to the emulsion

-1,3,5-triazine in the form of sodium salt, 0.3 ml of a 10% solution of oleylamine condensate with polyethylene oxide, 0.25 wetting agent and 0.125 ml of a 10% solution of dialkyl sulfosuccinate.

O

The coating of dispersion I was carried out on a triacetate substrate so that the Ag/m content was about

3.0 g. The coating of dispersion II was carried out on dispersion I so that the Ag/m content in this coating was 5.0 g.

Polev bulka states protective layers, exposure not measured sensitometrically and processing value for this topping E corresponds to the example. 1. The following- Table 0 2 Ag/m content D max ^{AD S} 0.1 Salt. δβ = 0.8.10 frosting E oh,0 0.15 2.51 0.8 31.5 600 seconds 45.1

Example 6

Three basic silver halide dispersions 1a, 1b, and 11 were precipitated in the same manner as in Example 5. However, instead of inert gelatin, an N-phenylcarbamoyl derivative of gelatin was used for precipitation, and after precipitation and Ostwald ripening to the required microcrystal size in the given dispersion, as shown in Example 5, the pH of the individual dispersions was adjusted so as to separate the solid phase. The pH values for the individual dispersions are given in Example 3. Washing of the dispersions was carried out by decantation of 1a and 1b and was the same as in Example 5. Spectral sensitization, preparation of the dispersion for coating, coating of the protective layer, processing, and exposure are the same as in Example 5.

O

The coating of dispersion 1 was carried out to a content of 2.9 g Ag/m and dispersion 11 to 4.8 g. The following table shows the unmeasured bicroenitometric and sensitometric values for coating F.

Table 7

Ag/m ^{2 D} o o ^Dmax ad ^With 0.1 Col. ^6d “ °» ⁸ · ¹⁰ “ ³ frosting F 7.7 0.16 2.50 0.8 31 .2 550 seconds 44.1 P fi E D U fe T YOU N A L E From U

1. Method of preparing black and white or chromogenically developed negative photographs

Claims (3)

1. Method of preparation of black and white or chromogenically induced negative photographic materials with a sensitivity of 24 to 31 ČSN, in which the resulting Fetegrefl material is produced by glaze of two or more individual photosensitive dispersions of different composition and different sensitivity, characterized in that , prepared from two separately prepared dispersions by mixing in a ratio of 0, 2 to 0.4: 1 and the resulting mean grain size 3 = 0.4 to 0.7 µm and a coefficient of variation of 17 to 25 which guarantees a high B _{| 8X} β mass for the second coating of silver bromide iodide based on a ratio of 85 up to 91: 1 to 15 mel% prepared by monobasic precipitation, using ammonia as a halogen halide, a mean halide particle size of 0.7 - 1.3 / b and a coefficient of variation of 20 to 30%, which regulates Ostwald ripening conditions, mainly temperature and maturation time. ^J 2. Method of claim 1, wherein the silver content of the individual layers are bonded steepness dispersions used, the required sensitivity, the size of the primary and applying activator zrma developing. 3. The method according to items 1 and 2, characterized in that the dispersions for the individual coatings are spectrally sensitized by combinations of optical sensitizers of the following formulas I to III or formulas IV to VI II III I ^c 2 ^H 5 I (ch ₂ ) ₃ so ₃ (ch ₂ ) ₃ so ₃ h IV VI