HU187581B - Method for making phitographic emulsiors pure from cadmium - Google Patents

Abstract

A light-sensitive silver halide photographic emulsion which includes indium (III) and/or lathanum (III) ions and which is substantially free of cadmium (III) ions and processes for its preparation. A better fogging stability is achieved and the sensitivity is increased.

Description

The present invention relates to a process for the preparation of cadmium-free photographic emulsions.

Cadmium salts have long been used in the preparation of silver halide photographic emulsions. They are mainly added to the alkaline halide-containing aqueous solution of gelatin before precipitation, usually with the aim of obtaining crystals of a smaller size with a higher contrast photosensitive layer. (P. Glafkides: Photographic Chemistry, Fountain Press, London, 1958, pp. 307, 318). Their stabilizing effect is also described (G. F. Duffin, Photographic Emulsion Chemistry Focal Press, London, 1965, p. 148).

A very small proportion of cadmium ions are incorporated into the peripheral layer of the crystal, while some of it is adsorbed on silver halide crystals, but a larger proportion remains in the gelatin phase. This part is washed out of the layer during photographic elaboration and can be released into the environment with sewage. This is undesirable.

In addition to cadmium, the effects of several metal salts have been studied. For example, salts of lead, mercury and copper have been found to reduce sensitivity (P. Glafkides, Photographic Chemistry, Fountain Press, London, 1958, p. 318), and lead and mercury are known to be environmentally polluting and therefore not applicable. to replace cadmium ions.

For the replacement of cadmium ions in high - contrast printing products

EC Patent 4,566,543 describes the use of complexes containing a cobalt (III) or chromium (III) cation, while EC Patent 1,500,278 discloses the use of a cationic ruthenium (III) complex. All of these substances work optimally when used in combination with tetraazaindole derivatives. These metal complexes often cause sensitivity reduction; in such cases, they are recommended for use in the gelatin auxiliary layer.

U.S. Patent 160,429, dated 1962, discloses an emulsion production method which otherwise does not contain cadmium ions prior to pouring into AgCl, Ag (Br, J) or Ag (Cl, Br, J) emulsion prepared by conventional technology. ΙΟ ^-3 -10 ^-2 mol / mol silver halide is added in an amount of indium salt.

In our experience, the addition of indium nitrate to emulsions without cadmium salt does not increase gradation, which can be explained by the effect of metal ions on silver halide crystals.

The metal ions added during the deposition are incorporated to a greater or lesser extent in the crystal peripheral layer and reduce the concentration of the inter-lattice silver ions (S. Takada, Phot. Sci. Eng. 18. 506/1974; 19/214/1975). As a result, the crystalline surface becomes more negative (H. A. Hoyen-Y. T. Tan; J. Coll. Interface Sci. 79 525/1981), which results in the formation of crystals of smaller size and more homogeneous distribution due to inhibition of growth, resulting in increased gradation. administered after the precipitation of metal ions are not incorporated into the crystal, and - as shown kadmiumionokra (Szucs, M. J. Signal AM 5/1980/217) - practically no crystal growth inhibitor effect. Under these conditions, the gradation is not increased, only the veil value is decreased.

The metal ions introduced during chemical maturation can only affect adsorption, sensitization and the formation of veils, thus affecting the sensitivity and the tendency of the photographic material to develop.

Metal ions added prior to casting have no effect on crystal size or on the development of sensitivity centers.

In accordance with the present invention, photographic emulsions may be replaced by compounds that provide at least equivalent photographic properties (sensitivity, gradation, maximum density, vein value) to the layers containing the cadmium salts without the above disadvantages.

The present invention is based on the discovery that the electron structure of metals plays a role in the action of metal ions on silver halides, according to which the indium (III) and optionally lanthanum (III) salts are used according to the invention, preferably in the form of nitrate or halide.

The invention has also been facilitated by the discovery that the indium (III) and lanthanum (III) ions used together at the time of impact enhance the effect of each other in increasing gradation and that the indium (III) ions added during chemical maturation at optimum concentration cause an increase in sensitivity.

The photosensitive photographic emulsion of the present invention is prepared by precipitating the silver halide, optionally in the presence of a rhodium or gold (III) or iridium (IV) salt, and subjecting the crystals formed to physical and chemical aging. standard emulsion is added to the resulting emulsion such as 1,3-diethylthiazole-pseudocyanine (color-sensitizer I) or 3-ethylthiazole-3'-ethyl-2'-thio-1 'as a color sensitizer per mole of silver halide, 0.05% by weight of 4'-oxazolidone-dimethylmerocyanine (color sensitizer II) and 5- (letyl-2-quinobenzimidazolo) -2 ': Γ-2: 3-thiazolidin3-one (color sensitizer III) os solution; 80-110 mL; 100-120 ml of a 50% solution of glycerol as a plasticizer; as a wetting agent 40-60 ml of a 4% solution of alkenyl succinic polyglyceride or dodecylphenol polyglycol ether or saponin; 20 to 30 ml of a 5% solution of formalin 5 as a tanning agent; 35-45 ml of a 1% solution of 1-phenyl-5-mercapto-tetrazole or mercaptobenzothiazole as a stabilizer. The emulsion additionally contains from 10 to ^{7 to} 5 x 10 * ¹ moles of indium (III) salt and optionally lanthanum (III) salt per mole of silver halide. The indium (III) - and optionally lanthanum (III) salts may be incorporated into the emulsion upon precipitation of the silver halide or during physical and chemical aging.

Indium (III) according to the invention - and lanthanum (III) salts are preferably administered ^_O 10 ^_1 -10 moles / mole silver halide amount.

The main advantages of the process according to the invention are as follows:

1. It allows the replacement of environmentally polluting cadmium ions in silver halide photographic emulsions.

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2. The indium (III) and, if appropriate, lanthanum (III) salts may act in very low doses.

3. Indium (III) - and optionally lanthanum (III) salts added during silver halide deposition inhibit the growth of photographic veils during storage rather than cadmium ions.

4. Indium (III) salts also exhibit a sensitizing effect when used during maturation.

The following embodiments illustrate the use of the process of the present invention:

Example 7

In a 3% gelatin solution containing 250 ml of 0.05 molar potassium bromide and 0.08 molar sodium chloride, silver halide was precipitated with 0.1 molar silver nitrate at 62 ° C. After 15 minutes of heat treatment, 32 g of maturing gelatin are added and the heat treatment (also at 62 ° C) is continued for another 45 minutes. The resulting emulsion is cooled to 40 ° C, and the usual additives (90 ml of 0.05% w / w color-sensitizing II, 110 ml of 50% glycerol, 40 ml of 4% saponin solution, 20 ml) are added to an aliquot. ml of 5% strength by weight formalin, 38 ml of ⁵ s per one 1-phenyl-mercaptotetrazole% - 1 mol of silver halide, and then applied to a paper substrate 10 of ² g / dm ² of silver metal content (A).

The emulsion is prepared in such a way that the gelatine IO ³ moles of cadmium chloride is added to ⁰ (B) and then adding an amount specified in Table 1 instead of indium nitrate, cadmium chloride (C).

Characteristics of photographic light-sensitive layers obtained in (AHD) emulsions of Table ⁵ illustrate the first aspect. (A sensitograms exposed to 2800 K color temperature of an incandescent lamp, and developed with the solution containing less than 18 ° C, 2 minutes, 1 g methol, 4 g of hydroquinone, 20 g of anhydrous sodium sulfite, 10 g of anhydrous sodium carbonate, 1 g of potassium ⁰ um bromide - 1 liter in water).

Table 7

Emulsion The addition of the metal salt is denominated in _{m (} * _{/ mol} Treatment way Relative sensitive- ness Average gradient D _m ,. up Veil 18 'C 2 ' 30 'C 10 ' (THE) - _ F 100 1.43 2.02 0.04 0.11 I 71 1.22 2.06 0.05 0.25 (B) CdCl ₂ 10 ² F 86 1.48 2.04 0.03 0.13 I 73 1.53 2.08 0.04 0.28 (C) In (NO ₃ ) ₃ 10 * ⁶ F 81 1.46 2.10 0.05 0.13 I 81 1.54 2.07 0.03 0.13 IO ² F 53 1.63 2.06 0.04 0.09 I 54 1.58 2.01 0.02 0.12

(Note: F = fresh, untreated sample, I = 50 'C after 5 days incubation).

Example 2

To emulsion (A) of Example 1, In (NO ₃ ) ₃ (E) is added 5 minutes after the addition of the maturing formate, followed by the procedure described in Example 1 below. The results are shown in Table 2.

Table 2

Emulsion The metal salt Treatment- way Relative sensitivity Average Djnax Veil name administration mol / mol 18 'C 2 ' 30'C 10 ' (B) CdCl ₂ 10 ² F 100 1.48 2.04 0.03 0.13 I 85 1.53 2.08 0.05 0.26 (E) In (NO ₃ ) ₃ 10 ^ F 114 1.50 2.02 0.03 0.11 I 108 1.43 2.06 0.05 0.14 IO ⁵ F 110 1.46 2.05 0.02 0.11 I 104 1.42 2.03 0.04 0.11 10 ⁴ F 96 1.44 2.03 0.03 0.12 I 92 1.41 2.05 0.05 0.11 10 ³ F 87 1.20 2.04 0.02 0.12 I 85 1.18 2.04 0.05 0.12

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Example 3

The emulsion of Example 1 (A) was prepared by double-jet precipitation by adding 0.02 moles of cadmium chloride (I) to the brine; 0.02 moles of cadmium chloride and rhodium chloride (J); and 0.1 moles of cadmium chloride (K), as described in Example 1 below. The test was carried out without then cadmium ion in the silver nitrate, indium nitrate (I) and the salt solution of rhodium chloride, the silver nitrate indium nitrate (Mn) was added, and ₅ so that the salt solution of gold chloride, indium nitrate (N) is added to the silver nitrate, and ammonium hexachloridate is added to the brine, and indium nitrate (P) is added to the silver nitrate. The results are a

Table 3 shows.

Table 3

Emulsion The metal salt name Treatment way Relative sensitive- of Average gradient ^D mx Veil 18'C 2 ' 30 ° C 10 ' (I) CDCI 0.2 F 100 2.9 2.10 0.04 0.09 I 87 2.8 2.10 0.05 0.10 ' (J) CdCl ₂ 0.2 F 42 3.8 2.12 0.04 0.12 RhClj 2 · IO ^-7 I 44 3.3 2.13 0.04 0.13 (R) CdCl ₂ 0.1 F 150 2.4 2.10 0.02 0.05 I 129 2.3 2.10 0.03 0.10 (L) In (NO ₃ ) ₃ 10 " ² F 147 2.4 2.16 0.03 0.09 I 132 2.3 2.14 0.04 0.13 (M) In (NO ₃ ) ₃ 0.1 F 56 3.7 2.10 0.04 0.08 RhClj 4 · 10 ~ ⁷ I 50 3.4 2.12 0.04 0.12 (N) In (NO ₃ ) ₃ IO ' ² F 161 2.52 2.16 0.03 0.09 HAuC1 ₄ IO ' ⁵ I 158 2.47 2.12 0.03 0.10 (P) In (NO ₃ ) ₃ 10 ' ² F 150 2.70 2.12 0.04 0.10 (NH ₄ ) ₂ IrCl ₆ IO ' ⁶ I 143 2.73 2.10 0.05 0.11

Example 4

The test described in Example 3 is also carried out by adding lanthanum chloride to the saline solution, indium nitrate to the silver nitrate, or by adding lanthanum chloride to the saline solution or indium nitrate only to the silver nitrate to show synergistic effect (R1). ..R6). The amounts of salt added and the results are shown in Table 4.

Table 4

The Metal Salt Emulsion. denomination of feed additive _{m (} J _{/ mol} Treatment way Relative sensitive- of Average gradient ^D max Veil 18 'C 2 ' 30 ° C 10 ' rl In (NO ₃ ) ₃ IO ² F 147 2.40 2.16 0.03 0.09 I 132 2.30 2.14 0.04 0.13 R2 LaCl ₃ IO ' ² F 78 2.52 2.15 0.05 0.08 I 59 2.47 2.14 0.05 0.08 R3 In (NO ₃ ) ₃ IO ' ² F 100 2.80 2.12 0.05 0.09 LaClj 10 ' ² I 96 2.60 2.19 0.05 0.08 R4 In (NÖ ₃ ) ₃ 10 ^-3 F 102 2.11 2.06 0.03 0.09 I 97 2.02 2.04 0.04 0.10 R5 LaClj IO ' ³ F 86 2.27 2.08 0.04 0.09 I 82 2.14 2.17 0.05 0.10 R6 In (NO ₃ ) ₃ IO ' ³ F 93 2.43 2.10 0.05 0.09 LaClj 10 ³ I 91 2.29 2.09 0.06 0.10

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Example 5

250 ml of a 3.2% gelatin solution containing 0.03 molar sodium chloride were stirred at 60 ° C while stirring in 0.1 ml of silver nitrate in 50 ml of water and 0.040 mol of potassium bromide in 50 ml of water. and 0.060 moles of sodium chloride. After 12 minutes of heat treatment, 28 g of maturing gelatin are added, and the heat treatment is continued for an additional 45 minutes, following the procedure of Example 1 (S).

The test is then repeated so that the silver nitrate solution of indium nitrate gave ⁵ golu a) the precipitation (T), b) 5 minutes after the introduction of the gelatin ripening, during chemical ripening (V) or c) before casting (Z).

The results are shown in Table 5.

Table 5

The Metal Salt ^Emulsion 'XlT Treatment way Relative sensitive- of Average gradient ^D m " Veil 18 * C 2 ' 30 'C 10 ' (S) no F 100 2.30 2.06 0.03 0.20 I 100 2.06 2.06 0.04 0.27 (T) In (NO ₃ ) ₃ 10 ' ² F 62 2.90 2.Π 0.04 0.12 I 68 2.75 2.16 0.05 0.17 (V) In (NO ₃ ) ₃ 10 ' ⁵ F 135 2.18 2.05 0.05 0.12 I 124 2.12 2.06 0.06 0.14 IO ² F 83 2.20 2.06 0.04 0.10 I 92 2.10 2.06 0.04 0.12 (Z) In (NO ₃ ) ₃ 10 ' ⁴ F 158 2.30 2.02 0.03 0.27 I 135 2.07 2.06 0.04 0.29 10 ' ³ F 123 2.30 2.04 0.05 0.22 I 126 2.10 2.07 0.05 0.28 10 ~ ² F 107 2.20 2.04 0.05 0.19 I 123 2.10 2.06 0.05 0.23

It is apparent from the examples shown that the indium nitrate alone or lanthanum chloride, ₃₅ illet- ve other suitable metal salts when administered to a cadmium equivalent substitute for the different transmitter átlaggradienst photographic emulsions.

From the results of Table 5, it can be seen that only cadmium-free emulsion can exert a gradation-enhancing effect when added to _{4Q at} the time of precipitation. By introducing the indium salt into the system during chemical maturation, it increases the sensitivity at optimum dosage (see also Table 2) and reduces the veil value compared to the metal-free emulsion. Indium nitrate added before casting does not increase gradation.

By replacing a smaller amount of cadmium salt (Table 1), the indium salt produces a better vein value with practically the same sensitivity and average gradient. When replacing larger amounts of cadmium salt (Table 3), an increase in sensitivity can be observed with practically the same average gradient and veil value.

Indium (III) - salt was coadministered and lanthanum (III) obtained gradation larger than ⁵⁵ in the case where they are added separately (Table 4).

Claims (2)

1. A process for the preparation of photosensitive photographic emulsions containing silver halide free of cadmium ion by precipitation of silver halide, optionally in the presence of a salt of radium, gold (III) or iridium (IV), physical and chemical maturation of the crystals formed; with the addition of plasticizers, wetting agents, tanning agents and stabilizers, characterized in that, at the time of precipitation into the emulsion or during physical or chemical maturation, 10 ^{-7 to} 5 * 10 * moles of indium (III) salt and optionally ⁵⁰ lanthanum ( III) salt is added. 2. Process according to any one of claims 1 to 3, characterized in that the indium (III) salt is indium (III) nitrate, the lanthanum (III) salt is lanthanum (III) nitrate or a halide.