Photosensitive element having an aluminum base and silane intermediate layer

Claim 1

An improved light sensitive element for use in preparing an offset printing plate by imagewise exposure comprising an aluminum base which has been pretreated and anodically oxidized, a positive- or negative-working light sensitive layer and an intermediate layer between said aluminum base and said light sensitive layer, the improvement comprising an intermediate layer which consists essentially of a silane hydrolysis product, condensate or mixtures thereof which has hydrophilic properties, said silane being selected from compounds of the formula (I) X--(CH.sub.2).sub.y --Si(R.sup.1).sub.n (OR.sup.2).sub.3-n (I) where R 1 and R 2 are identical or different and are each alkyl of 1 to 9 carbon atoms or aryl of 6 to 12 carbon atoms; and X is one of the radicals ##STR5## ##STR6## ZO 3 S--, HalO 2 S--, ZO 3 S-Ar-- or HalO 2 S-Ar--; where R 3 is hydrogen, alkyl of 1 to 9 carbon atoms; a carboxylic acid radical of 1 to 9 carbon atoms or a carboxylic anhydride ring formed from said carboxylic acid radical and the ##STR7## radical bonded to R 3 ; R 4 and R 5 are identical or different and are each alkyl of 1 to 9 carbon atoms or aryl of 6 to 12 carbon atoms; R 6 is hydrogen, alkyl of 1 to 9 carbon atoms or aryl of 6 to 12 carbon atoms; Z is hydrogen or an alkali metal; Ar is arylene of 6 to 12 carbon atoms; Hal is chlorine or bromine; y is an integer from 1 to 4 and n is 0, 1 or 2.