Light sensitive diazonium compounds having both bisulfate and zincate parts, method of making the compounds and compositions utilizing them
AssigneePrecision Lithograining Corp.
InventorAlbert S. Deutsch
Life of this patent
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Abstract
A water soluble diazonium salt composition made by the condensation of diazoaryl amines and aldehydes and precipitated to form a polymeric anionic species having both ZnCl.sub.4.sup.= and HSO.sub.4.sup.- moieties. These composition are blended with suitable binders, colorants and other optional components to produce light sensitive coating compositions. When applied to aluminum substrates, these light sensitive coating compositions form lithographic printing plates that are especially stable under high humidity conditions. Such plates may be developed by either water alone or by water which contains surfactants and/or a small amount of an organic solvent.
Claims20
A compound having the formula:
- ##STR4## wherein the diphenylamine groups are solely connected by --CH.sub.2 -- groups;
- and
- having a mixture of anions X.sup.- comprising from about 45 to about 94 mol percent ZnCl.sub.4.sup.- and from about 6 to about 55 mol percent HSO.sub.4.sup.-, and n ranges from about 2 to about 50.
A light sensitive composition which comprises a water dispersible polymeric binder in an amount sufficient to bind the composition components, and a compound having the formula:
- ##STR5## wherein the diphenylamine groups are solely connected by --CH.sub.2 -- groups;
- and
- having a mixture of salons X.sup.- comprising from about 45 to about 94 mol percent ZnCl.sub.4.sup.- and from about 6 to about 55 mol percent HSO.sub.4.sup.- ;
- and n ranges from about 2 to about 50, in an amount sufficient to render the light sensitive composition sensitive to actinic radiation.
A process for preparing a composition having the formula:
- ##STR6## having a mixture or anions X.sup.- comprising from about 45 to about 94 mol percent ZnCl.sub.4.sup.= and from about 6 to about 55 mol percent HSO.sub.4.sup.- ;
- and n ranges from about 2 to about 50 which comprises
- (a) reacting a 4-diazodiphenylamine with an aldehyde in the presence of sulfuric acid, to thereby produce a diazonium polymer;
- (b) cooling the result from step (a) with ice water until a temperature of from about 10.degree. C. to about 30.degree. C. is attained, with a sufficient volume of water to produce a concentration of the diazonium polymer ranging from about 0.6 weight percent to about 1.5 weight percent;
- and
- (c) precipitating the diazonium polymer resulting from step (b) with zinc chloride in an amount of from about 3 to about 6 times the weight of the diazonium polymer, which zinc chloride is added from an aqueous solution at a concentration of from about 15 weight percent to about the saturation point.
Dependencies are inferred from the claim text.