DE596421C - Photographic fade color layers - Google Patents

Description

GERMAN EMPIRE

ISSUED ON
May 4, 1934

REICH PATENT OFFICE

PATENT LETTERING

CLASS 57 b GROUP 18 oi

144926 IVbI57 b Date of publication of the patent grant: Ip. April

I. G. Farbenindustrie Akt.-Ges. in Frankfurt a. M. *)

Photographic fade color layers

Patented in the German Empire on July 22, 1932

It is known to be used in photographic fade color layers to use gelatin or cellulose derivatives as binders. With the normal cellulose derivatives one is in each case limited to those fade dyes and sensitizers that are in the same Solvent are soluble from which the cellulose derivative has been poured. These layers show the disadvantage that they cannot be treated with aqueous pickling solutions, What is necessary above all after copying the image to make it more resistant to light close. However, the use of gelatin as a binder includes one large range of dyes that have very good fading properties, but are not sufficiently soluble in water that they are not mixed with aqueous gelatin solutions can be. For these dyes it is desirable to use a binder which is also soluble in the organic solvents for the dye, but on the other hand provides a layer which is sufficiently swellable in water. This attribute is above all necessary to remove the fade-out color layers after copying of the picture with aqueous pickling solutions, for example tannin and tartar emetic, to make it more lightfast.

It has now been found that as binders showing these properties, quite partially hydrolyzed cellulose esters and cellulose ethers are particularly suitable. Suitable Cellulose esters and ethers are obtained by using more highly acidylated cellulose esters or higher alkylated cellulose ethers are partially hydrolyzed. Be for this purpose Cellulose esters or ethers treated with saponifying agents, with some of the esterified or etherified hydroxyl groups is exposed again. As a saponifying agent acids or alkalis come into question. Temperature and duration of exposure chosen according to the degree of saponification desired. These are hydrolyze products Soluble in organic solvents, but show with increasing degree of hydrolysis also an increasing swellability in water. You can therefore both from purely organic Solvents such as pouring from a solvent mixture with added water, and it is therefore also possible to use both water and alcohol-soluble fading dyes or to use other accessories.

Furthermore, these layers can be used because of their increased swellability in water aqueous fixatives are treated. It has also been found that these

*) The patent seeker stated as the inventor:

. 'Dr. Bruno W'endt in Dessau, Anhalt.

Layers in contrast to z. B. to layers of normal cellulose acetate the fixing process can train as a pickling process and thereby obtain more genuine and also insoluble colors. As a result of the insolubility of the pickled dyes, it is also much easier to get the mostly only in organic solvents soluble sensitizer after pickling remove the layer. The new layer

iQ ten therefore offer over the well-known Layers of cellulose esters have practically important advantages. They unite in relation to each other the advantages of cellulose derivatives (solubility in organic Solvents, formation of coherent films with sufficient mechanical properties, Swellability in organic solvents) with those of gelatine (swellability in water, pickling ability) and thus differ significantly from the previously proposed Layer substances for the bleaching process.

A hydrolyzed cellulose acetate with an acetyl content of 44 to 48 0/0. This is in methanol methylene chloride 3: 7 soluble. In this solvent mixture are all in Water sparingly or insoluble basic fading dyes easily soluble, and you can mix them with the cellulose acetate solution without difficulty.

example

To produce the casting solution for the bleaching layer, 30 g of hydrolyzed Cellulose acetate (acetyl number 46) swelled in 240 g of methylene chloride. For this one gives the Solutions of 80 mg of Nile blue in 30 g of methanol and 60 mg of selenopyronine, prepared from Monoethyl-o-PhenetLdin in 30 ecm of methanol, 90 mg resorcinol benzioindimethyl ether borofluoride in 10 ecm of methanol, 5 g of maleic acid in ι ο ecm of methanol, 5 g of diethylallylthiourea in 10 ecm of methanol. After adding these solutions, the hydrolyzed acetate dissolves very quickly. After filtering, this solution is poured onto baryta paper.

This layer is exposed through an original. The resulting image is fixed, by treating it as follows:

i. 15 minutes in 25 percent aqueous Tannic acid solution, 2. 5 minutes in water, 3. 5 minutes in 5% aqueous emetic tartar solution and optionally 5 minutes in Soprozentigena alcohol for removal of the thiourea derivative.

Claims (1)

Claim: Photographic fade-out color layers, characterized in thati the binder for the dyes made from partially hydrolyzed cellulose esters and ethers consists. Berlin, printed in the