US2513238A - Dry mixes for use in electrolytic - Google Patents

Description

Patented June 27, 1950 DRY MIXES FOR USE IN ELECTROLYTIC RECORDING Harold G. Greig, Princeton, N. J., assignor to Radio Corporation of America, a corporation of Delaware No Drawing. Original application November 4, 1944, Serial N0. 562,032. Divided and this ap plication September 26, 1947, Serial No. 776,411

4 Claims. 1

The present invention relates to dry stable mixes for use in preparing solutions for the electrolytic preparation of colored images on a traveling web or band which for simplicity may be referred to as a receiver. This application is a division of my co-pending application Serial No. 562,032, filed November 4, 1944, now Patent No. 2,442,596, granted June 1, 1948.

The production of color image records by electrolyzing a solution containing a diazotizable amine, a nitrite, an electrolyte such as sodium chloride, potassium chloride and the like and a coupler, is disclosed in Solomon U. S. P. 2,306,471. In my co-pending application Serial No. 562,033, filed November 4, 1944, now Patent No. 2,493,963, granted Jan. 10, 1950, and entitled Electrolytic Recording, it is suggested that there be substituted for the amine and nitrite of such solution a stabilized diazo amino compound. Manifold advantages, including an improved stability of the records to light, are obtained when operating in this way. It has been found that these two methods are the most eiiicacious for electrolytically producing color image records especially in facsimile recording. By the term facsimile recording as used herein is meant not only the reproduction on the receiver of a pre-existing subject, but also the reception of subject-matter in the process of creation or formation.

The production from dry mixes of the electrolytic recording solutions with which the receiver is treated in these methods has manifest advantages. If the dry mix be storage stable, it can be prepared in bulk and stored for a considerable period of time. Furthermore, it can be shipped to whatever destination desired at a much lower cost than the water solutions. The production of dry mixes suitable for use in these processes has accordingly been a desideratum in this art.

The couplers which have been found to give best results in the methods previously outlined are naphthol sulfonic acids, of which chromotropic acid is an example. This acid is usually sold in the form of its mono-sodium salt. This salt is acid and if incorporated into a dry mix containing a diazotizable amine and a nitrite or a stabilized diazo amino compound, it would induce premature diazotization and coupling in the first instance, and premature splitting of the diazo amino compound and coupling in the second 2 instance. If, on the other hand, the alkalinity of such compounds be increased to avoid such premature action by the utilization of the usual alkalies such as sodium hydroxide, sodium car- 'lbonate, potassium hydroxide, and the like, it is found that the records obtained suffer because of a poor shade of the images and because of the instability of the background to light. It has therefore been considered preferable, up to the present time, to prepare fresh solutions for electrolytic recording rather than to produce dry mixes which can be stored and shipped for use at a time in the future despite the advantages inherent in the latter course of action.

I have now discovered that the objections to in water in the concentrations in which they are used in electrolytic recording to give a pH of approximately 9.5. The alkalinity induced by using the alkylolamine prevails during storage so that no premature diazotization or splitting of the diazo amino compound with resulting coupling takes place. Due to the stability of such compounds or to some other as yet unascertained property thereof, solutions in water or another suitable solvent such as alcohol of dry mixes containing the same, produce on electrolysis, dark image records the background of which has a much higher permanence to light than records" obtained where the alkalinity has been produced by resort to the usual alkalies.

It is accordingly an object of my invention to produce dry mixes for the production of electrolytic recording solutions wherein the coupling component is a naphthol sulfonic acid in which at least one sulfonic acid group has been neutralized with an alkylolamine.

It is a further object of my invention to produce dry mixes for the production of electrolytic" recording solutions wherein the coupling compound is a naphthol polysulfonic acid in which at least one sulfonic acid group has been neutralized with an alkylolamine.

It is a further object of my invention to pro-,

duce storage stable dry mixes containing a pri mary aromatic amine, a nitrite, an electrolyte and a naphthol sulfonic acid as the coupling compound in which at least one sulfonic acid group has been neutralized with an alkylolamine.

It is a further object of my invention to produce storage stable dry mixes of a stabilized diazo amino compound, an electrolyte and as the coupling compound a naphthol sulfonic acid at least one of the sulfonic acid groups of which has been neutralized with an alkylolamine.

It is a further objectof my invention to produce records by electrolyzing a solution containing a source of diazonium ions, an electrolyte, and as a coupling compound a naphthol sulfonic acid in which a sulfonic acid group has been neutralized by an alkylolamine.

It is a further object of my invention to produce dry mixes for forming electrolytic recording solutions in which the coupling compound is chromotropic acid, the sulfonic acid groups of which have been neutralized by an alkylolamine.

Further objects of my invention will appear as the description proceeds.

It has been stated the dry mixes of the present invention contain either a diazotizable amine and a nitrite or a stabilized diazo amino compound. In other words, the diazonium ions which react with the coupling component are produced by the action of the facsimile recording current on the diazotizable amine and the nitrite on the one hand and the diazo amino compound on the other hand. The diazotizable amine or the aryl amine from which the stabilized diazo amino compound is produced may be any of the diazotizable aryl amines utilized in the azo dyestufi" art. Examples of such amines are given in the aforesaid Solomon patent and in my aforesaid co-pending application Serial No. 562,033 and entitled Electrolytic Recording,

to which attention is directed. Such amines are, for example, naphthionic acid, 4.4'diamino-diphenyl-2.2-disulfonic acid, 4.4-diaminodiphenyl 3.3'-disulfonic acid, 4.4'-diaminodiphenylamine-Z-sulionic acid, orthotolidine-2.2-disulionic acid, alpha-naphthylamine-4.8-disulfonic acid, alpha-naphthylamine--sulfonic acid, 0- anisidinei-sulionic acid, and the like. These amines when used in the form of the stabilized diazo amino compounds may have their diazonium compounds stabilized with an aliphatic amine such as ethanolamine, diethanolamine, carcosine, diisopropanolamine, diinethylamine, diethylamine, and the like, by an aromatic amine which does not readily couple, such as 4-sulfo-2- aminobenzoic acid, 2-methyl-amino-4-sulfobenzoic acid and the like, or by a heterocyclic amine, such as alpha-carboxy pyrrolidine, alp'ha-l-alpha-Z-dicarboxy pyrrolidine, piperidine, carbazole and the like.

The stabilized diazo amino compounds are prepared by diazotizing the primary aromatic amine and reacting the resulting diazonium compound in an alkaline solution with one of the aforesaid organic amines which does not easily couple to form an azo dye. It is advisable when producing the stabilized compound, to use an excess of the stabilizing amine over the quantity theoretically necessary to produce the stabilized diazonium compound since otherwise difficulties may be encountered in the stability of the records to light.

As the coupling component there may be used any naphthol sulfonic acid at least one sulfo group of which has been neutralized with an alkylolamine. Such compounds have the following formula, assuming that diethanolamine is the neutralizing agent:

Z-naphthol-G-sulfonic acid 2-naphthol-8-sulfonic acid 1-hydroxy-8-acetylamino naphthalene-3.6-diSu1- ionic acid 1 hydroxy-S-amino naphthalene-3.5-disulfonic acid l-hydroxy 8 amino naphthalene-6.7-disulfonic acid 1.8-dihydroxynaphthalene-3.6-disulfonic acid l-hydroxy 8 amino naphthalene-3.6-disulfonic acid l-hydroxy naphthalene-3.6-disulfonic acid 2-hydroxy-naphthalene-3.6-disulfonic acid 1.7-dihydroxy naphthalene-3.6-disulfonic acid Z-hydroxynaphthalene-G.8-disulfonic ac-id 1-hydroxynaphthalene-3.6.8-trisulfonic acid 1.3-dihydroxynaphthalene-5.7-disulfonic acid 1.5-dihydroxy-naphthalene-2.7-disulfonic acid 1.5-dihydroxynaphthalene-3.7 -disulfonic acid 1.7-dihydroxynaphthalene-3.7-disulfonic acid l-hydroxy '7 amino naphthalene-3.6-disu1fori ic acid and the like. Best results, however, have been secured with the salts of chromot'ropic acid and the use of the salt of this acid represents the preferred embodiment of my invention.

The preparation of the alkylolamine derivative of the coupling compound may be carried out by dissolving the alkyl'olamine in a volatile, inert solvent such as alcohol, and reacting the coupling component with the solution of the alkylolamine. Upon heating to a temperature of to C., the excess alkylolamine is removed with the alcohol. a solvent, morpholine may also be employed and by proportioning the quantities of the alkylolamine and the morpholine a mixed alkyola'minem'orpholine salt is obtained.

It has been previously pointed out that at least one of the sulfonic acid groups of the coupling component is neutralized with the alkylola'inine'. If the naphthol sulfonic acid employed is a monosulfonic acid, only the monoamine salt is formed, in which case the preparation is effected by using 1 mol of the. naphthol sul'foni'c acid with at least 1 mol of the alkylolamine. Where the coupling component is a polysulfonic acid, the ratio of the reactants will vary depending upon the particular naphthol polysulfonicacid selected and the results desired. If, for instance, a disulfonic acid such as ohromotropic acidis used-,

It might be noted'th'at as such amonoamine salt may be prepared by using 1 1 mol of the-sulfonic acid for each molof the algroup is neutralized with an alkylolamine and" another group is neutralized by means of another radical. Thus, by using 'a" naphthalene disulfonic acid such as chromotropic acid, with l mol of an alkylolamine and 1 mol of morpholine', the mixed alkylolamine-morpholine salt results.

The dry mixture which is used, irrespective ofthe source of the diazonium compound,must con-- tain an electrolyte, The electrolyteis preferably sodium chloride, although other common electrolytes such as potassium chloride, sodium bromide I and the like may be utilized with equally good results.

The preferred pH of the solution resulting from dissolving the dry mixture in water is between 9.5 and 11.5. In some instances, the alkalinity afforded by the salt of the coupling agent will not give the pH which is optimum for the component used. In that case, it is desirable to add a very small amount of an inorganic alkali such as sodium hydroxide, potassium hydroxide or the like. The quantity of this agent required will usually be from 1 to 2 grams per literof the recording solution.

Other ingredients may be incorporated-in the dry mix and in particular a wetting agent to facilitate the impregnation of the carrier by the solution. Suitable wetting agents are alkyl naphthalene sulfonic acids, for example, butyl naphthalene sulfonate and the like, the condensation product of a sulfonated benzene with chlorinated kerosene, said compound having the formula SOaNB where R represents the hydrocarbon radicals present in kerosene (see U. S. P. 2,220,099), and sarcosine and taurines, the nitrogen atom of which is acylated with a high molecular weight fatty acid, for example, oleic, palmitic and the like. The wetting agent will usually be present in an amount ranging from .05 to about 1 gram per liter of solution.

The invention will be further understood from the following examples, but it is to be remembered that these examples are illustrative and not limitative.

Example I .06 gram mols of diethanolamine are dissolved in cc. of ethyl alcohol.

.03 gram mols of dry, finely ground chromotropic acid is slurried from one-half hour with this ethyl alcohol solution. The product is then dried at a temperature of 65 to 70 C. There is thus obtained a purple-gray product having a dry weight of 21.42 grams and which is the di-salt of diethanolamine chromotropic acid.

.2 gram mol of diethanolamine salt of chromotropic acid, .4 gram mol of the diazo compound from diazotized naphthionic acid and diethanolamine,

3.3 grams of the condensation product of naphthale'ne sulfonic acid with chlorinated kerosene,

163.8grams of sodium chloride, and 8.2 grams of sodium hydroxide are thoroughly ground and mixed together to produce a uniform dry product.

74.5 grams of this mixture are dissolved in a liter of Water for the preparation of a facsimile recording solution, This solution has a pH of 10.1. Records produced with such a solution are a dark blue purple, the background of which has a high stability to light.

The diazo amino compound from diazotized naphthionic acid and diethanolamine referred to andice. Diazotization is complete almost as soon as the solution is added and the diazonium com-= pound, which is quite insoluble, precipitates out as a thick, creamy slurry. Stirring is continued for one hour to obtain the product in a form in. which it is more easily filtered. Filter cake ob tained upon filtration is reslurried in approxi-- mately 500 cc. of water until a smooth paste is: obtained. This paste is added slowly at 10 to 15 C. over a two-hour period with rapid agitation tor a solution of cc. of diethanolamine in 250 cc. of water while maintaining a temperature of 10 to 15 C. in an ice bath to minimize decomposition.

The reaction is complete when all the diazoniuin compound has been added. Th resulting solution is amber in color and may stain paper with a reddish tint. It must be alkaline when tested with brilliant yellow test solution.

2 grams of sodium hydrosulfite are added and the solution stirred for one hour at room temperature to clear away the red-staining impurities. 20 grams of activated charcoal are incorporated and the temperature raised to 50 to 55 C. for /2 hour for the purpose of further clarifying the solution and to remove basic impurities. Sodium y chloride is then added to precipitate the diazomum compound which is filtered off, washed and dried.

Example II 30 cc.of ethyl alcohol.

.03 mol of chromotropic acid in a dry, finely ground condition is slurried for one-half hourwith this ethyl alcohol solution. The product. obtained upon drying at 65 to 70 C. has a dry Weight equal to 18.74 grams and is the di-mono-- ethanolamine salt. It is a dark gray in color.

This salt of monoethanolamine is employed in: the same manner as the diethanolamine treated; chromotropic acid of Example I to give a dry mix: suitable for electrolytic recording solutions. Bluepurple records of a good background stability to-- light are obtained upon submitting a receiver treated with a water solution of the dry mix to the action of an electrolytic current.

Example III .06 mol of triethanolamine are dissolved in 20 cc. of ethyl alcohol.

.03 mol of chromotropic acid in a dry, finely" ground condition are slurried with the alcohol so lution forhalf anhour and the reactionproduct-i is then dried 8.1365 to 70 C. The product obtained in-adryweightof 23.66 grams is a slightly gummy,

dark brown powder and is the di-triethanolamine salt.

The product when substituted for the diethanolamine treated chromotropic acid of Example I produces a dr mix which when used in electrolytic recording gives a blue-purple record.

Example I V' The procedure is the same as in Example I except that the chromotropic acid is replaced by l-hydro'icy-S-aminonaphthalene -'6."I-disulfonic acid. I

Example VI The. procedure is the same as in Example I' except that the chromotropic acid is replaced by2 hydroxy-naphthalene-3.G-disulfonic acid.

Example VII The procedure is the same as in Example I exceptv that the chromotropic acid is replaced by 1.7- dihydroxy-naphthalene-3.fi-disulfonic acid.

Various modifications of the invention Will occur to persons skilled in the art. and I therefore do notintend to be limited in the patent granted except as required by the prior art and the appended'claims.

I claim:

1. A storage-stable, dry mix for producing electrolytic recording solutions containing as its essential components a diazo amine compound capable of yielding a diazonium compound under the influence of an electrolytic recording current, a water soluble inorganic salt as the electrolyte in an amount to insure passage of the electrolytic recording current and a sufficient quantity. of a preformed salt of a naphthol sulfonic acid to couple with the. diazonium compound whenformedlto producean azo dyesaid'preformed salt.

having. the following constitution:

in which R is a member of the class consisting of. hydrogen, amino andacylamino, m is a num;

her from 1 to 3, n is a number from 1 to 2, and

Y is. a quaternary ammonium radical selected.

from the class consisting of monoethanol-ammonium, diethanol-ammonium, triethanol-ammonium, and di-isopropanol-ammonium, said compositionw'hen dissolved in water having a pH on the alkaline side any inorganic alkali present being inan amount not greater than 2 grams per liter of recording solution.

2.. A storage-stable dry mix for producing electrolytic recording solutions containing as its'essential components the diazo amino compound of! diazotized naphthionic acid and diethanolamine capable ofyielding: a diazonium compound undertheinfluence of an electrolytic recording current,-.awater'soluble inorganic salt as the electrolyte in. an amount to insure passage of the.

electrolytic recording current, and a sufiicient quantity of apreformed diethanolamine salt of v chnomotropic acidtocouple with the diazonium cqmpound when formed to produce an azo dye,.

said composition when dissolved in Water having a pH on. thealkaline sideany inorganic alkali present being in an amount not greater than 2 grams per liter ofrecording solution.

3 A fibrous sheet material impregnated with.

an aqueous solution of thecomposition of claim 1.

4. A fibrous. sheet. material impregnated. with an: aqueous solution-of.the-composition of claim 2.

HAROLD G. GREIG.

REFERENCES. CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2 ,088,506 Chambers July 27, 1937 2135;964 Dahlen Nov. 8, 1938 2,138,572 Etzelmiller Nov. 29; 1938 2331 53370 Nodler A r; 6, 1943- 2,42'1' ,3'6 7 Solomon May 27, 1947' 2,440.526 Solomon Apr. 27, 1948

Claims (1)

1. A STROAGE-STABLE DRY MIX FOR PRODUCING ELECTROLYTIC RECORDING SOLUTIONS CONTAINING AS ITS ESSENTIAL COMPONENTS A DIAZO AMINO COMPOUND CAPABLE OF YIELDING A DIAZONIUM COMPOUND UNDER THE INFLUENCE OF AN ELECTROLYTIC RECORDING CURRENT, A WATER SOLUBLE INORGANIC SALT AS THE ELECTROLYTE IN AN AMOUNT TO INSURE PASSAGE OF THE ELECTGROLYTIC RECORDING CURRENT AND A SUFFICIENT QUANTITY OF A PREFORMED SALT OF A NAPHTHOL SULFONIC ACID TO COUPLE WITH THE DIAZONIUM COMPOUND WHEN FORMED TO PRODUCE AN AXO DYE SAID PREFORMED SALT HAVING THE FOLLOWING CONSTITUTION: