CS239604B1 - A method of stabilizing highly sensitive photographic emulsions - Google Patents

Abstract

Stabilization of highly sensitive photographic emulsions by the action of a combination of 2-hydroxy-4,6-dichloro-1,3,5-triazine and alkoxypolyethylene oxide derivatives. The synergistic action of the above components results in a significant improvement in the ratio of sensitivity and haze Sq while maintaining the necessary steepness and, moreover, the decreases in sensitivity, steepness and maximum optical density during aging are significantly better.

Description

The invention relates to a method for stabilizing highly sensitive photographic emulsions.

When preparing highly sensitive photographic emulsions, the influence of other ingredients that determine the production of photographic materials often leads to a decrease in the photographic sensitivity of the emulsion, possibly to an increase in haze or a decrease in the steepness and maximum optical density. These undesirable properties sometimes appear immediately after coating, but most often only after a certain period of natural aging, i.e. during storage of the finished photographic material. The positive effects of individual ingredients of spectral sensitizers, development activators, or hardeners, on the photochemical properties of the photographic emulsion in some cases not only mutually eliminate each other, but often also bring undesirable qualitative features, for example an increase in haze, decreases in sensitometric values - steepness, sensitivity, etc., especially in the process of aging of the material.

The method of stabilizing highly sensitive photographic emulsions according to the invention by combining 2-hydroxy-4,6-dichloro-1,3,5-triazine and alkoxypolyethylene oxide of the general composition RO(CH ₂ CH ₂ O) _n CH ₂ CH ₂ OH, where R is a residue of a fatty alcohol, phenol, naphthol, alkylated phenol, aliphatic amine, amide, aliphatic acid, diamine or phosphoric acid ester, containing 6 to 30 carbon atoms and n = 30 to 100, does not have the above-mentioned disadvantages.

2-hydroxy-4,6-dichloro-1,3,5-triazine acts by itself as a hardener for photographic emulsions (FR 2 353 877? SU 499 546? JP 32 024). Alkoxypolyethylene compounds, for example polyethylene glycol with a molecular weight of 1 500 and higher, allylene oxide condensation products or their polymers and copolymers, increase the sensitivity of the emulsion (US 1 970 578; 2 240 472? 2 423 549;

441,389; 2,531,832; 2,533,990; GB 920,637; 940,051; 945,340; 991,608; BE 648,310 and others).

The synergistic effect of 2-hydroxy-4,6-dichloro-1,3,5-triazine results in a significant improvement in the sensitivity-haze ratio (SO _{Q 2} /Dq) when using the alkoxypolyethylene oxide preparation, ^while maintaining the required slope. In contrast, this does not occur when using another type of hardener, e.g. dimethylurea. In addition, the decreases in sensitivity, slope and maximum optical density during aging of the material are significantly lower.

Example 1

To a highly sensitive emulsion containing 4 mol % J , which is panchromatically sensitized with a mixture of common cyanine dyes and contains casting additives, e.g. wetting agents, 5 ml of an aqueous solution of the sodium salt of 2-hydroxy-4,6-dichloro-1,3,5-triazine in a 1 N sodium carbonate solution and 5 ml of a 10% solution of a condensate of lauryl alcohol with polyethylene oxide (80 ethylene oxide units) are added per 1 kg of emulsion containing 45 g of Ag. The emulsion is cast onto a triacetate support together with a gelatin protective layer containing common additives and 3.5 ml of a 5% aqueous solution of 2-hydroxy-4,6-dichloro-1,3,5-triazine. The sensitograms obtained are developed according to ČSN 66 6403.

The same panchromatically sensitized emulsion is used as a comparative test.

a) not containing a solution of sodium salt of 2-hydroxy-4,6-dichloro-1,3,5-triazine and a solution of lauryl alcohol condensed with 80 units of ethylene oxide. The required hardening effect is achieved by diffusion hardening from the protective layer using 10.45 ml of 7% dimethyl urea solution/1 kg of conventional gelatin protective layer;

b) not containing an aqueous solution of sodium salt of 2-hydroxy-4,6-dichloro-1,3,5-triazine, but containing 5 ml of a 10% solution of a condensate of lauryl alcohol with polyethylene oxide of n = 80/1 kg of emulsion. The required hardening effect is achieved by diffusion hardening from the protective layer using 10.45 ml of dimethylol urea solution/1 kg of a conventional gelatin protective layer;

c) containing 5 ml of a 5% aqueous solution of 2-hydroxy-4,6-dichloro-1,3,5-triazine/1 kg of emulsion; the gelatin protective layer contains 3.5 ml of the same substance/1 kg of protective layer.

The following table 1 shows the sensitometric values, relative swelling and melting point achieved for the individual tests. Ag/m content for all tests 3.8 g.

Table 1

Emulsion proposed • cf. 1. a) 2. compare 1. b) 2 . compare 1. C) 2. 1. 2. development time at D = 0.8 10 12 12 16 10 14 13 16 in minutes D _Q 0.22 0.28 0.21 0.45 0.26 0.63 0.22 0.25 ^D max 1.91 1.90 1.9 0 1.79 1.91 2.00 1.75 1.75 With _Ojl (ČSN) 20.60 20.30 20.90 18.50 21.00 18.30 19.20 19.50 swelling - 100% 136% - 142% - 98% melting point - 90°C - 66°C - 65°C - 98°C

1st - immediately after frosting

2. -3 days of terracotta at 50 °C and 30% relative humidity.

Example 2

To a highly sensitive emulsion with an iodide content of 5 mol %, which is panchromatically sensitized with carbocyanine dyes and contains coating additives, e.g. wetting agents, 6 ml of an aqueous solution of the sodium salt of 2-hydroxy-4,6-dichloro-1,3,5-triazine in 1 N sodium carbonate containing 5% by weight of 2-hydroxy-4,6-dichloro-1,3,5-triazine/1 kg of emulsion and 5 ml of a 10% solution of ethylene oxide condensate with lanolin (75 ethylene oxide units) per 1 kg of emulsion 2 containing 45 g of Ag are added. The emulsion is poured onto a triacetate support. The Ag content/m is 4 g. As comparative tests, the same basic emulsions were coated, where the emulsion was hardened by diffusion from the protective layer using dimethylurea and an unhardened emulsion containing polyethylene oxidized lanolin, 5 ml per 1 kg of emulsion. The obtained values are shown in Table 2.

Table 2

Sensitometric values after frosting and after standing in a thermostat at 50 °C and 75% relative humidity for 10 days.

Compared emulsions ^With 0.2 immediately after frosting ^D o steepness ^With 0.2 10 days in thermostat ^D 0 steepness A 100% 0.20 1.2 90% 0.22 1.1 B 105% 0.21 1.2 52% 0.82 0.8 C 132% 0.27 1.25 110% 0.43 1.08 D 130% 0.22 1.21 130% 0.23 1.19

A - 2-hydroxy-4,6-dichloro-1,3,5-triazine

B - emulsion hardened by diffusion from the protective layer using dimethylol urea

C - uncured emulsion containing polyethylene oxide condensate of lanolin (5 ml per 1 kg of emulsion) D - emulsion containing 2-hydroxy-4,6-dichloro-1,3,5-triazine and polyethylene oxide lanolin

Example 3

The procedure is the same as in Example 1, where instead of the combination of 2-hydroxy-4,6-dichloro-1,3,5-triazine and polyethylene oxidized lanolin, the combination is a 50% solution of 2-hydroxy-4,6-dichloro239604.

-1,3,5-triazine and polyethyleneanoxidized stearylamine (25 ethylene oxide units).

Claims (1)

SUBJECT OF THE INVENTION Process for stabilizing highly sensitive photographic emulsions, characterized in that 2-hydroxy-4,5-dichloro-1,3,5-triazine and an alkoxypolyethylene oxide of the formula I are added as a hardener to the emulsion. RO (CH ₂ CH ₂ O) _n CH ₂ CH ₂ OH, wherein R represents a fatty alcohol, phenol, naphthol, alkylated phenol, aliphatic amine, amide, aliphatic acid, diamine or phosphoric acid ester containing from 6 to 30 carbon atoms and 30 to 100, said hardener being added in an amount of 2 to 20 ml of a 5% aqueous solution and alkoxypolyethylene oxide added in an amount of 1 to 10 ml of a 10% aqueous solution, based on 1 kg of emulsion. Severography, n. P., MOST Price 2,40 Kčs