IL33344A - Light-sensitive reproduction material and process for the preparation of a printing form - Google Patents

Description

Beproduction Material and Process for the Preparation of a Printing Forntf nam diazp materials which contain in their copying layers two dlazo compounds of different known from Patent and Patent and the corresponding British Patent The object of each of these patents ia a diazotype material which is materially different from materials for the preparation of a printing Since diazotype materials are d eveloped with a coupler to make one single visible azo dye colored image each individual while printing plates are with agent which removes the areas which shall not accept p to a printing gorm for printing m numerous visible printing ink colored from each Individual it had been unlikely that the use of two dlazo compounds of different would result in a better reproduction of continuous tones in printing plate The following illustrate the in them the reproduction layers are always exposed under a step wedge having a density increment of per steps A solution consisting of methyl of the lphonio aoid ester of from British Patent tion and g of the sulphonib aoid ester of esterified in from British Patent Specification applied by of plate whirle to the surface of an aluminium plate whioh has been roughened by the then The reproductio laye of the reproduction material thus produced for 70 seoonde under a step usin an aro lamp as whioh is slightly doped for the ultraviolet range adjacent the visible violet After the reproduction layer is developed with an aqueous alkaline The exposure time is selected such that only those areas of the reproduction layer that exposed through the least step of the step wedge are completely removed during the plahographic printing forme thus obtained is inked up with black An image printed from this printing forme hows 9 to 10 in gradated shades of the forme in shows the eigne of after a run of If easae procedure the exceptio that instead of g eac of the two naphthoquinone d of ester used i which exposure must seconds to achieve comparable forme ie obtained from which an is printed which 8 steps the wedge in different of Iff g of the trlhydroxy the second compound are used correspondingly in which an exposure off 40 eeoonde required a printing forme is obtained which 7 steps in different shades of Example 2 The procedure in xample 1 except that the solution of methyl glyco g off cumylphenol eater of Example trlhydroxy of Example and g off a phenol exposure time resulting printing prints 7 to in She first eigne wea become apparent only a run of Iff g of the phenol ester used instead off of each of the two esters which oaee an exposure insufficientOCRQuality

Claims (1)

1. What olaiia A reproduction material the preparation of a printing of a layer and a reproduction layer disposed thereon which at least oompounds of the same chemical which oompounds differ in their that at leaet one of them is at least one and a half times as at least other toward the ligh emitted b a specific light which light causes a decomposition of all the said oompounds present in the A material as claimed in Claim i hich 40 to mo per cent of the possess higher as specified in Claim A material as claimed in Claim 1 or which the reproduction layer one or more acid esters one or more acid esters in a molar ratio 40 60 to 60 t 50 per by weight of calculated on the weight of A material as claimed in any of Claims 1 to whioh the layer support has a roughened surface with a roughening depth of to mm and that the reproduction layer covers the projections present in the layer support due to A material as olaimed in claim substantially as described in any one of the Examples A process fo preparation of a printing wherein a reproduction material as olaimed in any one of subjected to insufficientOCRQuality