Modified quinone-diazide group-containing phenolic novolak resins

An electrodepositable photosensitive modified phenolic novolak resin of general formula ##STR11## where Ar.sup.1 represents a divalent aromatic group linked through aromatic carbon atoms to the indicated groups --OR.sup.2 and --CH(R.sup.1)--,

• Ar.sup.2 represents a trivalent aromatic group linked through aromatic carbon atoms to the indicated groups --OR.sup.2 and --CH(R.sup.1)--,
• R.sup.1 represents a hydrogen atom or an alkyl, aryl or carboxyl group,
• R.sup.2 represents a hydrogen atom, an alkyl group, an alkyl group substituted by a hydroxyl or alkoxy group, or a group of formula --CO--R.sup.3 --COOH, --SO.sub.2 R.sup.4, --COR.sup.5 or --SO.sub.2 R.sup.5, at least 1% of the groups R.sup.2 representing a group --CO--R.sup.3 --COOH and at least 4% of the groups R.sup.2 representing a group --SO.sub.2 R.sup.4,
• R.sup.3 denotes a divalent aliphatic, cycloaliphatic, aromatic or araliphatic group,
• R.sup.4 denotes a 1,2-benzoquinone diazide group or 1,2-naphthoquinone diazide group of formula ##STR12## the free valency bond of formula III being in the 4- or 5 -position, R.sup.5 represents a carboxyl-free monovalent aliphatic, cycloaliphatic, aromatic or araliphatic group, and
• n denotes zero or an integer of 1 to 20.