Process for producing a negative-working lithographic printing form utilizing solvent mixture of mono-(C.sub.1 -C.sub.4) alkyl ether of diethylene glycol and a solvent having boiling point between 50.degree. and 150.degree. C.

A process for producing a negative-working photosensitive lithographic printing form comprising the steps of:

• (a) providing a solvent mixture consisting essentially of, in admixture,
• (i) from about 10 to 50% by weight of at least one mono-(C.sub.1 -C.sub.4)alkyl either of diethylene glycol, and
• (ii) at lest one organic solvent having a boiling point between about 50 and 150.degree. C.,
• (b) dissolving a negative-working photosensitive mixture which contains a negative-working photosensitive diazonium salt polycondensation product in an amount sufficient to cause a layer of the mixture to become insoluble when it is exposed to actinic radiation and a polymeric binder which is insoluble in water but soluble in aqueous alkaline solution in said solvent mixture, said binder being present in an amount sufficient to form a uniform layer of the mixture on a substrate,
• (c) applying said photosensitive mixture dissolved in said solvent mixture to a base to form a layer, and
• (d) drying said layer wherein said diazonium salt polycondensation product comprises
• (i) units derived form condensable compounds selected from the group consisting of aromatic amines, phenols, phenol ethers, aromatic thioethers, aromatic hydrocarbons, aromatic heterocyclics and organic acid amides, and
• (ii) units derived from compounds of the formula (R.sup.8 --R.sup.9 --).sub.p R.sup.10 --N.sub.2 X, where
• X is the anion of the diazonium compound,
• p is an integer from 1 to 3,
• R.sup.8 is an aromatic radical containing at least one position capable of condensation with an active carbonyl compound,
• R.sup.10 is a phenylene group,
• R.sup.9 is a single bond or one of the groups:
• --(CH.sub.2).sub.q --NR.sup.11 --,
• --O--(CH.sub.2).sub.r --NR.sup.11 --,
• --S--(CH.sub.2).sub.r --NR.sup.11 --,
• --S--(CH.sub.2 CO--NR.sup.11 --,
• --O--R.sup.12 --O--,
• --O--
• --S--or
• --CO--NR.sup.11 --
• wherein
• q is a number from 0 to 5,
• r is a number from 2 to 5,
• R.sup.11 is hydrogen, an alkyl group containing 1 to 5 carbon atoms, an aralkyl group containing 7 to 12 carbon atoms or an aryl group containing 6 to 12 carbon atoms, and
• R.sup.12 is an arylene group containing 6 to 12 carbon atoms.