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Color problems

Color Couplers Color Formers

D As we know with regard to black and white film rendering processes, if this bleaching agent reduces silver salts and turns them into metallic silver, then it is oxidized from the other side. Hydroquinone, for example, is converted to quinone according to the following equation:

Silver bromide - hydroquinone = silver + hydrobromic acid + quinone, and in the same way as the previous example. Other display agents, including all the reducing agent known as Paraphenyline Diamine, which is a very important reducing agent in color imaging processes.

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And based on the previous property, Rudolf Fischer discovered in 1909 that as a result of the reduction process carried out by the previous salt, some very other substances arise, and if they combine with chemical compounds (such as those we mention below), pigments of different colors will be formed. The blue-green dye Cyan (1) is formed by the combination of the reaction products with a-naphthol, the magenta dye is formed by the combination of the reaction products with pyrazolonderivatives, and the yellow dye is formed by the combination of the reaction products with Acetoacetic esters. Color Couplers, as a result of displaying under the previous conditions, two images will be formed as follows: Active

(a) A silver image resulting from the reduction of a salt to metallic silver

x (b) A picture of the dye Dye Image: It results from the union of the oxidation products of paraphenylene diamine with the previous compounds that form the colors. This process is known as color development

人 is three: a formula which its discoverer Fischer called chromogenic development, and this designation is still valid today in many references. It can be concluded from the foregoing that the purpose of the color rendering process is to form

Pictures, and therefore Dye Images must be in the three layers of the colored film: (a) We require that an image of the yellow dye be formed in the upper blue sensitive layer, and therefore a substance must be included in its composition to form the yellow color (b) and that it be formed A picture of the dye cochineal magenta in the green sensitive layer, in which a substance is included to form the color cochineal. (C) That a form of cyan dye is formed in the lower red sensitive layer, and therefore a substance must be included in its composition to form the cyan color. And in the introduction of color problems within the materials that make up the sensitive layers, which allows the color film to be shown in one display solution only instead of treating it in three successive display solutions, in order to facilitate the individuals who wish to show their color films with their knowledge after photographing them.

Some technical problems arose as a result of the inclusion of color-forming materials within the composition of the three sensitive layers. These problems are: the inequality of the degree of interaction of the oxidation products of the reducing agent with the color-forming materials in the three barriers that make up the film, so the intensity of the interaction increases in one layer over the other, This results in one color being more intense in one layer than other colors in subsequent layers

. for colors

- The color-forming substances are soluble in nature

Water, which is an attribute that must be present in these materials for the following reasons: (1) In order to facilitate the mixing of these materials in the sensitive gelatinous dough, completely and evenly in all its parts. (b) To ensure full interaction between the outputs of the rendering process and the formed materials

Although it is clear from the above that it is preferable for the materials that form the colors to be easily soluble in water, on the other hand, acceptable reasons appear that suggest the desire for these materials not to be soluble, because if they were soluble, they would also dissolve in water. The display solution and the three materials that make up the colors mix and spread through the three sensitive layers, making it difficult to control them, so we see colors in one of the sensitive layers.

In the movie, she shouldn't have been in it. In view of the previous considerations, it was finally found that the necessary properties

It is available in the materials that form the colors, it is to be soluble when preparing the sensitive dough for each of the three layers, and it is required to prevent its movement after the end of its manufacture or during the rendering operations. Herein lies the difficulty in selecting color-forming materials in the color film industry. D

It was possible to overcome this problem by choosing color problems of two large molecules (1) Large Molecular size, although the color problems chosen in the previous form are still soluble so that they are easily mixed with the gelatinous emulsion while it is in a liquid state, but their size is relatively large.

(1) It will create an obstacle that prevents its movement in the small distances in the layer of gelatin, which becomes sponge-like when it turns into a solid state. To simplify the understanding of the wisdom of following this method, it can be said that it is in increasing the size of the color problem particles, in order to prevent their movement inside the gelatin, similar to what we find. Obstacles when trying to remove a large tree branch cut from it among the rest of the branches of this dense tree. And Kodak references mention) that it was possible to overcome the tendency of color problems to move inside the sensitive emulsion, by making the color problems inside microscopic globules of very small organic materials, and they are anchored through the sensitive layer. It is also useful to make color problems inside these pellets as a way to protect them from chemical interaction with silver salts. And when showing the film in the colored highlighting solution, the oxidation products of the show agent (reducing agent) permeate those globules, spread inside them and interact with the color problems, according to what was mentioned above. This method is known as the Protected coupler process