DE1207791B - Process for the preparation of highly sensitive photographic emulsions for latent silver halide grain interior images - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY GERMAN # | Ä PATENT OFFICE

EDITORIAL

Int. σ .:

G 03 c

Number: File number: Filing date: Display date:

German KL: 57 b-8/01

1 207 791
F 44440IX a / 57 b
November 14, 1964
December 23, 1965

The invention relates to a method of manufacture a highly sensitive photographic emulsion for the production of latent halosilver grain interior images.

When treating a photographic silver halide emulsion, the fine silver halide grains creates a latent image that can be developed. However, the latent image does not arise only on the surface, but also inside the crystals. The latent inner image can only then with brought into contact with the developer or developed ίο if it contains substances that Can solve halogen silver. Such substances are e.g. B. sulfites, thiosulfates, thiocyanates, amines or copious amounts of alkali halide.

In the specially prepared silver halide emulsion, it happens that the latent image is predominant arises within the halogen silver grains. If such halosilver grain interior image emulsions after developed during exposure, a visible image will only be obtained if halogen silver is dissolving Substances are contained in the developer. Such emulsions are widely used, e.g. B. receives a direct positive reversal image with subsequent appropriate treatment. When the exposure the emulsion layer takes place with very intense light or the emulsion layer during exposure in If water or a developer bath is immersed, a surface image is also obtained in the emulsion. if the emulsion layer after exposure under such special conditions, e.g. B. in the camera is exposed with an object, the latent image produced is subject to the influence of the already formed latent surface image. With appropriate choice of exposure and development conditions an emulsion layer can be obtained in which the density of the surface image in the part of the weak camera exposure is high and the density of the halogen silver grain interior image due to longer exposure is increased. In this way a direct positive reversal image is obtained with a developer which does not contain any substances that dissolve halogen silver (surface developer).

Other uses have also been suggested for such emulsions Description must be mentioned.

In order to achieve the above-mentioned object, an emulsion is needed in which the formation of the surface latent image is strongly suppressed and the latent image is formed substantially in the interior of the halide silver grains. Such an emulsion is hereinafter referred to as an emulsion for latent silver halide grain interior images. The production takes place in the process of making
high sensitivity photographic emulsions
for latent halogen silver grain interior images

Applicant:

Fuji Shashin Movie Kabushiki Kaisha,
Minamiashigara-machi, Ashigarakami-gun,
Kanagawa-ken (Japan)

Representative:

Dr. G. W. Lotterhos

and Dr.-Ing. H. W. Lotterhos, patent attorneys,

Frankfurt / M., Annastr. 19th

Named as inventor:

Hirozo Ueda,

Minamiashigara-machi, Ashigarakami-gun,

Kanagawa-ken (Japan);

Wolfgang Friedrich Berg, Scheuren-Forch

(Switzerland)

Claimed priority:

Switzerland of November 19, 1963 (14 439)

for example according to US Pat. No. 2,592,250 in such a way that in the presence of inert gelatin a silver salt is precipitated which at least partially contains such a silver salt as AgCl or AgCNS is more soluble in water than AgBr. Then the water-soluble silver salt becomes the less soluble one Silver bromide or silver iodide converted.

A major disadvantage of such emulsions is that they are not chemically sensitized can, as is possible with the usual emulsions for latent surface images. Therefore have the known emulsions for latent halosilver grain interior images only have a low sensitivity.

The invention aims at the preparation of an emulsion for latent silver halide grain interior images which has high photographic sensitivity. In the method of the invention is based on halogen silver, which is already chemically sensitized, further halogen silver deposited. The newly formed, made of halogen silver existing surface has extremely low effectiveness in creating a latent surface image, while inside the

509 759/514

chemically sensitized halogen silver grains selectively produce a latent halogen silver grain interior image.

According to the invention, a chemically sensitized main emulsion becomes very fine-grained with another Mixed emulsion containing fine, non-sensitized halide silver grains, with before or after the coating is treated with a solvent for halogen silver such as sulfite, thiosulfate, Thiocyanate, amine, or copious amounts of alkali halide until there is silver halide on the grains the first emulsion has deposited. The fine halogen silver grains are therefore first loosened and dissolved deposited on the halide silver grains of the main emulsion. For example, a with Silver bromide saturated 3N KBr solution can be used. When the silver potential of this solution after is shifted on the oxidizing side, the latent image is easily oxidized. To avoid this, can include an oxidation-reduction buffer, such as ferric-ferro-ions, and a complexing agent in the Solution are given, whereby the oxidation properties are reduced. As halogen silver can be used under the prerequisite that the fine particles of the auxiliary emulsion due to their dimensions and / or of chemical nature are more soluble than the particles of the main emulsion; z. B. is silver bromine than fine particles to be preferred to silver bromide.

To further explain the invention, the following exemplary embodiments are given.

example 1

A blue-sensitive silver bromide emulsion containing 5 mol percent silver iodine was made to be extremely sensitive by heat treatment in the presence of a sulfur-containing compound. An equivalent amount of an emulsion, the particles of which had a diameter smaller than one-tenth the particle diameter of the main emulsion, was separately prepared and mixed with the former main emulsion. The mixture was coated on a support so that the amount of silver was 100 mg / dm ² . The coating was treated with a solution prepared as follows:

In 70 cc of distilled water, 35.7 g of KBr were dissolved at a temperature at 20 ⁰ C aqueous 0.1 N AgNO ₃ solution was added until a yellow solution around the cloud had formed. Ig K ₂ SO ₄ · Cr ₂ (SO ₄ ) ₃ · 24H ₂ O and, after its dissolution, distilled water to make up 100 cm ^{3 were} added to the cloudy solution. To deaerate the solution, nitrogen was bubbled through for one hour, then the liquid was sealed with petroleum ether.

To prepare a second solution, 80 cm ^{3 of} distilled water were freed from the dissolved air using nitrogen, then 2.61 g of K ₈ SO ₄ , 3.0 g of Fe ₂ (SO ₄ ) S, 2.1 g of FeSO ₄ · 5H were added ₂ O and 35.7 g of KBr were added and made up to 100 cm ³ with distilled water. This solution was kept like the former.

As a third solution, 50 cm ^{3 of} the second solution were mixed with 2.5 g of citric acid and stored as above.

The three solutions were mixed and the mixture allowed to settle for half a day. With the supernatant solution, the emulsion coating was applied for 5 to 10 minutes 16 ° C treated. The treatment was carried out with the solution sealed off.

The emulsion layer was then washed for 15 minutes with running water 6-8 ° C, then for 5 minutes at 16 to 20 ⁰ C with a l% aqueous solution treated the disodium salt of ethylenediaminetetraacetic acid, then again for 15 minutes with running water

ίο Washed from 6 to 7 ° C and finally dried.

The sensitivity of an emulsion treated in this way is shown in the following table. The sensitivity is as The logarithm of the reciprocal of the exposure required for a density of fog +0.1.

Be Untreated inner Treated clearing emulsion Receive emulsion Upper find- Upper! inner area- lightly- area- | Receive recommend speed feel 2-10 ² find- 3.7 find- j sensitive- 2 ■ ΙΟ " ¹ opportunity 1.2 opportunity Treatment f 2 · ΙΟ " ⁴ 0.8 1.3 - (*)! 1.1 before J. 2-10 ² 1.6 2.0 -! 1.9 Exposure [ 2 · 10- ¹ 1.0 1.5 - j 1.5 Treatment ί 2-10 ⁴ 0.8 1.7 -! 0.4 after < 1.5 - '1.1 Exposure [ 1.1 - i 0.8

(*) The surface sensitivity was so low that it could not be measured.

The table shows the results both for the treatment according to the invention before exposure and for also indicated after exposure.

The exposure times were 200, 2 * "" ¹ and 2 * 10 -4 * seconds. A solution for surface development and a solution for internal development were used for development. It can be seen from the table that the treatment according to the invention increases the internal sensitivity of the halogenated silver grains of the emulsion and the surface sensitivity is substantially reduced.

Example 2

600 g of a Bromjodsilberemulsion (particle size 0.4 to 0.5 microns) 100 g Bromjodsilber and 5 mole percent silver iodide, a sulfur-containing compound (gelatin with a high content of sulfur compound) was kept warm for 60 minutes at 55 ⁰ C in the presence and so brought to the highest sensitivity. This emulsion was mixed with an equivalent amount of a separately prepared, non-sensitized emulsion whose halide silver particles were smaller than 0.1 microns.

35.7 g of KBr were dissolved in 90 ecm of distilled water, then 0.1 N aqueous silver nitrate solution became at 20 ° C. until a yellow cloudiness had formed throughout the solution.

This solution was mixed with the emulsion held for 30 minutes at 5O ⁰ C and then cooled to 35 ° C. The cloudy solution was charged with 20 cc of a 5% aqueous solution of chrome alum and 10 cc of a 6 ° / _o aqueous solution of saponin was added. This mixture was coated on photographic paper of 60 g / m ² in an amount of 80 cm ³ / m ² and then dried.

The sensitometric test showed that the emulsion was fully an emulsion for latent Halogen silver grain interior images was.

The main emulsion to be used according to the invention can, in addition to that mentioned in the examples Sulfur sensitization also through reducing sensitization, a noble metal or polyalkylene glycol and other means to be sensitized.

The emulsions prepared according to the invention for latent halosilver grain interior images can be used for the following Purposes or processes are used: for the generation of direct positive reversal images, z. By the method of U.S. Patent 2,497,875 in which such an image is developed the latent halosilver grain interior image is created by means of a fog developer, and for the production a high density, high gamma reversal image including the fog developer with a fog inhibitor is added (U.S. Patent 2,497,917). The reverse image of a silver pigment and dye is produced by developing the latent silver halide grain interior image with a color developer (U.S. Patent 2,507,154). For the reverse development of the latent halosilver grain interior, a developer containing a hydrazine compound was used (U.S. Patent 2,563,785). A hydrazine compound is added to an internal halide silver grain emulsion (U.S. Patent 2,588,982). To the Two exposures of different intensities are produced to produce a direct positive reversal image (U.S. Patents 2,912,326, 2,912,327 and 2,912,328). The emulsions can be used are used for Sabattier image reversal or for a procedure that has the effect of low-intensity desensitization or a destruction of the latent image. The emulsion for latent halosilver grain interior images can also be mixed with other emulsions, e.g. B. can be a color photographic Material with three photosensitive emulsions will have two layers if one of the three Emulsions is a halosilver grain interior image emulsion (U.S. Patents 2,453,765 and 2,490,751). Copy-out emulsions of high sensitivity can also be produced according to the invention. In all these applications achieve a higher sensitivity and stability than the known ones Halogen silver grain interior image emulsions.

Claims (2)

Patent claims: 1. Process for the production of highly sensitive photographic emulsions for latent halosilver grain interior images, characterized in that a chemically ripened as usual and a sensitized emulsion having a second, very fine-grain, non-sensitized silver halide grain containing emulsion is mixed and that in this mixture before or after coating by means of a solvent the fine particles are dissolved until their halosilver is deposited on the coarser particles Has. 2. The method according to claim 1, characterized in that a sulfite as a solvent Thiosulfate, a thiocyanate, an amine or alkali halide is used. 509 759/51 + 12.65 © Bundesdruckerei Berlin