| 摘要 |
An alkaline-resistant and excellent ink-water balance lithographic printing plate is provided comprising a layer of a photosensitive composition on an aluminum substrate. The photosensitive composition contains (a) a photosensitive diazo resin comprising a condensation product of an aromatic diazonium salt, a copolymerizable compound free of diazonium groups and an active carbonyl-containing compound and (b) a binder comprising a high molecular weight acrylic. The aluminum substrate is treated for use by graining, etching with a caustic solution containing from about 1.0% to about 4.75% of an alkali metal hydroxide by weight, and hydrophilizing. In a preferred embodiment the photosensitive composition comprises: (a) a photosensitive diazo resin comprising a copolymer containing the recurring monomer units having the general formula (I) -- <IMG> wherein R1, R2, and R3 each denote separately a hydrogen atom, a halogen atom, an alkyl group having from 1 to 3 carbon atoms, or an alkoxy group having from 1 to 6 carbon atoms, X denotes PF6 or BF4, R is a hydrogen atom, an alkyl group having 1 or 2 carbon atoms or a phenyl group, at least one of R4 and R5 is hydroxyl or carboxyl and the other is a hydrogen atom, hydroxyl, carboxyl, an alkyl group having from 1 to 3 carbon atoms, an alkoxy group having from 1 to 6 carbon atoms, halogen, -SO3H or its salt, or -SO2H or its salt, R6 is a hydrogen atom, an alkyl group having 1 or 2 carbon atoms or a phenyl group, and wherein the ratio of m to n is from about 70:30 to about 85:15, and (a) has an average molecular weight of from about 2,000 to about 3,000 and (b) a binder comprising a high molecular weight acrylic co-polymer, wherein the ratio of (a) to (b) by weight is from about 0.033/1 to about 0.17/1.0. Aluminum substrates for use in such printing plates and methods for producing such substrates and printing plates are also provided.
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