US2286701A - Diazotype printing material - Google Patents

Description

Patented June 16,1942

UNITED STATES PATENT OFFICE DIAZOTYPiPRINTING MATERIAL Georg Werner.

iesbaden-Blebrich, Germany,

asslgnor to Kalle & Co. Aktiengesellsehaft. Wiesbaden-Blebrlch, Germany No Drawing. Application June 22, 1940, Serial No. 341,901. In Germany June 8, 1939 8Claims.

7 The present invention relates to light-sensitive layers for diazotype purposes with the aid of which positive copies may be obtained.

It has been found that diazo compounds of printing materials containing the said newdiazo compounds.

Compounds of the kind named in which the etherified inercapto group is. a thialkyl group are especially valuableand well suited for the production of diazotype materials.

The two alkyl groups bound to oxygen as well as the alkyl group bound to sulfur should preferably contain not more than 4 carbon atoms and in this connection reference is made to the methyl and ethyl groups. The alkyl groups may also have substituents, for instance hydroxy groups. The alkyl group combined with the sulfur atom may also be substituted by a carboxyl group whereas the two ether alkyl groups may be substituted by alkoxy groups, such as methoxy groups or ethoxy groups as substituents. The compounds in which the alkyl groups are free from any substituents are, however, the most useful.

If required, the benzene nucleus may be further substituted by substituents, such as are usually present in compounds employed for diazotype purposes. It is, however, to be recommended that the substituents introduced into the molecule should not impair the solubility of the diazo compounds in water. v

The diazo compounds named possess to a very large extent the properties desired for diazotype purposes. They are solid substances which are very strongly colored so that the bleaching of the light-sensitive layers prepared therewith is accordingly marked. Moreover, the diazo compounds possess a high sensitiveness to light as well as an excellent stability. The light-sensitive layers prepared therewith are, therefore, very stable during storage and require only a very short period 01; exposure to light. The prints obtained with the light-sensitive layers show very dark lines if suitable azo-components, for instance .phloroglucine, are used and are furthermore distinguished by a pure ground. The good solubility in water of the diazo compounds, particularly the good solubility of the zinc chloride double salts especially suitable for diazotype purposes is to be particularly emphasized.

The diazo compounds forming an object of the present invention are suited in the first place for the manufacture of one-component diazotype papers to be developed by the moist developing method. They may, however, likewise beused for the manufacture of two-component papers which contain the azo component besides the diazo compound and may be developed by the dry developing method.

The favorable properties of the diazo compounds mentioned could not be foretold. Attempts have already been made for to use the diazo compound of amino-hydro-quinone-dlmethyl-ether for diazotype purposes. Said compound, has, however, not attained any industrial importance in this respect, due to the facts that the layers prepared'with such compound are very unstable and their sensitiveness to light is not satisfactory. Moreover, the prints therewith .show unfavorable shades. Photographic printing paper having satisfactory properties can', therefore, not be obtaine'dwith the aid of these compounds. By the introduction of the usual substituents into the molecule of the known diazo compound the properties which are important for diazotype purposes cannot, in general, be materially improved. It is, therefore, very surprising, that by the introduction of an etherified mercapto group which constitutes a substituent entirely unusual in the diazotype process an extraordinary improvement of the properties is attained.

The diazo compounds used according to the present invention may be prepared as follows:

A solution adjusted to a very weak acid reaction (pH=ca. 5.5 to 6.5) of the diazonium chloride obtained in the usual manner from a 2.5-dialkoxy-1.4-nitraniline is caused to flow into an aqueous solution heated to about 70 C. of the equimolecular quantity of potassium xanthogenate. The xanthogenate produced in this manner from the diazo compound with separation of nitrogen and formation of potassium chloride (Leuckart reaction) and in most cases constituting an oil is saponified by boiling it for a prolonged time with an alcoholic solution of potassium hydroxide until the thiophenolate is obtained. The solution of the thiophenolate filtered over charcoal is reacted with dimethylsulfate, .diethylsulfate, sodium chloroacetate, ethylene-chlorhydrine or similar etherifying agents; whereby the thio-ethers insoluble in soda lye precipitate. These 2,5-dialkoxy-1enitro- 4-thiophenol-ethers are transformed in the usual manner by reduction and diazotation of the bases mended that the thiophenolate first be isolated by precipitating it with an acid and the etherification then efiected in an alcoholic solution.

produced The process may be illustrated by the following formulae:

wherein R1 and R2 stand for alkyl and Rs stands for alkyl, aralkyl or aryl.

The following examples serve to illustrate the invention, but they are not intended to limit it thereto:

1. The diazo compound from 4-ethylmercapto- 1-amino-2.5-diethoxybenzene is produced in the manner described above from 1-nitro-2.5-diethoxy-i-aniline. of the diazo compound is a well crystallized yel- 10w substance which decomposes at 141-143 C. The melting point of the corresponding nitrocompound (Formula V above) is 925 C.

Paper is coated with a solution of 3 grams of the zinc chloride double salt of. the diazo compound from 4-ethylmercapto-1-amino-2.5-dieth oxybenzene, 1 gram of tartaric acid, 1 gram of boric acid, 5 grams of thiourea and .2 gram of saponine in 100 cc. of water. The dried material is then exposed to light under an original, and developed with a developer containing .4 gram of phloroglucine, 6 grams of di-sodium-phosphate, 8 grams of trisodium-citrate and 1.5 grams or acid sodium tartrate in 100 cc. of water. Prints having dark blue-black lines are thus produced.

2. The diazo compound from 4-methylmercapto-1-amino-2.5-diethoxybenzene is produced in the manner described above from l-nitro-2.5- diethoxy-4-aniline. The zinc chloride double salt of the diazo compound decomposes at 143 C. The corresponding nitro-compqund (Formula V above) melts at 108 C.

3 grams of the zinc chloride double salt of the diazo compound from 4-methy1mercapto-1-amino-2.5-diethoxybenzene, 3 grams of 2-oxynaphthyI-B-biguanide, 3 grams of tartaric acid, 1 gram of boric acid, 6 grams of sodium 1.3.6-naphthalene-trisulfonate, 3 grams of thiourea and .2 gram of saponine are dissolved in 100 cc. of water and the solution is painted on to paper. The dried paper is sensitive to light and very stable. The prints prepared therewith may be developed for instance with ammonia gas.

3. A diazo photographic printing material is obtained by sensitizing a suitable base with a solution or 3 grams of the zinc chloride double salt of the diazo compound from 4-hydroxyethylmercapto-l-amino 2.5 diethoxybenzene, 1 gram of citric acid, 5 grams of sodium sulfate, 3 grams of thiourea, .2 gram of saponine in 100 cc. of water. The mentioned diazo compound which is a strongly yellow colored substance decomposes at 142 C. The corresponding intro-compound (Formula V above) melts at 109-,110 C.

Diazo photographic printing material for the moist development may be obtained in a similar derived from the following aminocompounds: r

The zinc chloride double salt 1 manner. by means of diazo compounds which are 4-ethylmercapto- 1 amino 2.5- dimethoxybenr zene, 4-methylme'rcapto- 1 amino 2.5- diethoxybenzene, 4-butylmercapto-l-amino-2.5-diethoxybenzene, 4-benzylmercapto-1-amino-2.5-diethoxybenzene, 4-phenylmercapto-l-amino-2.5-diethoxybenzene, 4-methylmercapto-1-amino 2.5 dimethoxybenzene, 1- amino 2.5 dimethoxyphenyl r 4 thioglycolic acid, 4-ethylmercapto 1 amino 2.5 di(methoxy-wmethoxy) benzene.

The last-named compound has the following formula:

S.C:H5

HZCO-HICO 0 0H,.OCH;

4. A very useful diazo photographic printing material is obtained by painting paper, film or any other suitable base with a solution of 3 grams of zinc chloride double salt of the diazo compound from 4-(n)propylmercapto-l-amino- 2.5-diethoxybenzene (point of decomposition 141 C.), 1 gram of citric acid, 1 gram of tartaric acid, 4 grams of aluminium sulfate, .5 gram of zinc chloride, 5 grams of thiourea and .2 gram of sapanine in cc. of water. The prints obtained with this material may be developed with a commercial developer containing phloroglucine.

A similar result is produced by applying the corresponding isopropyl-mercapto diazo come pound.

I claim:

1. A diazo printing material consisting of a sheet support carrying a light-sensitive layer which comprises a diazo compound of an aminohydroquinone-dialkyl-ether containing in paraposition to the diazo group an etherifled mercapto group.

2. A diazotype printing material as claimed in claim 1, wherein the said etherified mercapto group is a thioalkyl group.

3. A diazotype printing material consisting of a sheet support carrying a light-sensitive layer which comprises a diazo compound of an aminohydroquinone-dialkylether containing in paraposition to the diazo group a group S-alkyl wherein the said alkyl groups contain not more than four carbon atoms. d

4. A diazotype printing material consisting of a sheet support carrying a light-sensitive layer which comprises a diazo compound of the following general formula:

wherein X stands for a diazo group, Y for a member of the group consisting of an unsubstituted alkyl group, an alkyl group which contains a hydroxyl group as substituent and an alkyl group which contains a carboiwl group as substituent and R and R for a member of the group consisting of an alkyl group and an alkyl group which contains an alkoxy group as substituent wherein the various alkyl groups contain at most four carbon atoms.

5. A diazotype printing material consisting of a sheet support carrying a light-sensitive layer which comprises a diazo compound of the following general formula:

wherein X stands for a diazo group, Y for an 6. A material of the kind described comprising a paper and a light-sensitive layer on the said paper which layer comprises the diazo compound from 4 methylmercapto-l-amino-2.5-diethoxybenzene. v

'7. A material of the kind described comprising a paper and a light-sensitive layer on the said paper which layer comprises the diazo compound from 4-ethylmercapto-1-amino-2.5-diethoxybenzene.

8. A material of the kind described comprising a paper'and' a light-sensitive layer on the said paper which layer comprises the diazo compound from 4-(n) propylmercapto-l-amino 2.5 diethoxybenzene.

GEORG WERNER.