IL33311A - Light-sensitive material for the preparation of printing formes suitable for printing continuous tones,process for the preparation of such light-sensitive material and process for the preparation of the printing formes - Google Patents

Description

FOB THE OF FQBMES PBOCESS THE Off SUCH AND PBOCESS ΡΒΕΡΑΒΑίΧΟΰ Off THE FOBMES B This Invention is concerned with a process for the production of material for the preparation of printing ormes for printing continuous which material consists of a support for the reproduction layer and on said support a particular reproduction layer to be invention concerns a process fior the paration of a printing materials suitable for the preparation of printing formes have been known for a long They consist of a support for the necessary reproduction layer and the reproduction layer disposed For the preparation of printing these materials are exposed to an original corresponding to writing or an image pattern to be printed being and the exposed reproduction layer then If an image to be printed which contains continuous a screen is usually placed between light source and in addition to the Among the known reproduction materials are such ascan be stored for several weeks or months before they are converted a printing Good keeping qualities of the reproduction layer depend upon the selection of a suitable material is known which a compound the reproduction layer as the it is known that certlan materials containing diazide compounds their reproduction layers are suitable for preparation of printing formes which print continuous without having to use a screen during their The knovn materiel which enable the preparation of unscreened continuous tone printing formes a printin which prints a positive image of the original used for it has been assumed that for the preparation of less printing formes for printing continuous only such reproduction materials can be used as possess a relatively thin light sensitive reproduction Reproduction material for the reproduction of continuous tones is also known which contains a compound the reproduction layer and in addition 20 per cent by weight of a calculated on the weight of the the resin was not incorporated for the purpose of increasing the thickness of the reproduction but the reproduction layers were made relatively solutions containing only 12 per cent by weight of solids being used for their Due their relatively thin the known materials suitable for the re aration of rintin formes for the reroduction so good as to leave norroom for The present invention provides in the first place a process o or production of a reproduction material for the reparation of printing formes suitable for printing continuous tones wherein a solution of a qiiinone diazide in dimethyl dimethyl or which solution contains at least per cent by weight of the quinoneddiazlde and also resin in the proportion of to 100 per cent by calculated on the weight of quinone the sum of the weights of resin and quinone diazide being at least per cent by weight of the is applied to a support in such a manner that after drying a dried coating obtained having a thickness of to If an original is to be used for exposure of thereproduction hich a positive of the to be the quinone zide compound for be an amide or an ester of an one diazide If an original is to used which is negative of the image to be the quinone diazide compound for be a diazide The resin contained in the reproduction laye may be a chloroacetic a a polyurethane polyvinyl an a resin based on maleic an epoxy copolymer of and unsaturated carboxyllc or a polyaer acid As regards the quality of the gradation o tone the resin content shpould be relatively but whe a long printing run is to be a somewhat higher resin content is If it is desired to have a tone values of good but to have a relatively long printing resin contents between 25 per cent by calculated on the weight of the diazide compound contained in the reproduction layer are to be Reproduction layers of a t cknevs of to microns are preferred for materials fromwhich relief printing formes are to be prepared by usin the exposed and developed reproduction layer as an etch Reproduction materials which to be exposeduunder a negative original order to produce a positive printing preferably hasas reproduction layer of same order of Reproduction material layer of reproduction longer are the exposure times necessary for processing reproduction carrying layers thickness mor than microns are no suitable for practical Reproductio layers of the thickness of micronsmay be one by means of a plate applicator roll and doctor a reproduction to be prepared which isto be under a positive a solution advantageously applied to the support which contains at least per cent by of The the of continuous tones achieved by the reproduction material produced according to the invention to some also on the solvent used for ts has that the quality of reproduction material produced is the the more strongly pola the solvent used forlits beet reproduction was obtained by using dimethyl formamide as the The present invention further provides a process for preparation o a printing for printing continuous wherein reproduction material produced according the process of invention exposed under a continuous tone without the use of a followed by development in the conventional After exposure under a continuous tone original and the reproduction material produced according to the invention yields a printing image as regards th gradation of tone values or the printing run or is superior to known veproduction material intended for the preparation of printing ormes for printing continuous The following Examples illustrate the the percentages being by Examples Brushed aluminium plates were separately by means of a plate with different solutions containing a then In all the solution used consisted dimethyl formamide as the a novolak of a melting range of 108 to which was identical in all and an diazide compound which was in all and consisted of the diester of 2 whose hydroxyl groups in the positions had been with The preparation of this compound is from Specification The ollowing Table sets forth the compositions by weight of the various coating solutions In this 0 means the quinone diazide means resin FK means and is the quantity of resin per calculated on the weight of the quinone diazide Composition1 the Solution in t SD 2 10 32 25 4 100 The reproduction materials thua obtained exposed through a step wedge with a density Increment of per in such a manner that so muchlightpassed through the most transparent ste of the wedge that the following development the reproduction material only the area of the reproduction layer exposed through most step of the completely removed from the The exposure times ranged from to When they were used for the planographic printing produced in Exam les reproduced an image of the step wedge in which the number of steps listed the table under column was As can be seen from Table the reduction the number of printed steps is not up to a resin content of based on the weight of the ulnone but at a resin content of the luence of the resin is already considerabl In column 7 or Table the thickness of the copying layers is in microns under the The planographic printing formes obtained according to Examples 1 to 3 were used for printing in offset printing until the resulting prints showed of printing runs obtained are entered in coluns 8 and 9 of Table column 8 showin under the heading the runs obtainable rom printing formes which had been subjected to temperaturehad not been subjected to a temperature above after whereas column 9 under the heading the printing runs obtainable from printing formes whose printing images ha been hardened after by heating them to about It ca be seen particular with a resin content of 10 to 15 per cent based on the of the diazide compound a considerable increase the number of prints obtainable is while the quality of reproduction of the continuous tones is only slightly reduced Up to the last the continuous tones are excellently reproduced by the printing In Examples 5 to 25 the changes made compared with the Examples referred to are not such as to lead to any appreciable changes in coating 20 A planographic printing orme was produced inthe manner described in Example 2 above with exception that instead o a brushed aluminium laminate of paper and aluminium foil was coated on the aluminium The planographic printing thus obtained showed 5 to 6 in the printing It was that reproduction material the reproduction layer applied relatively aanooth surface less results than does reproduction reproduc io layer is o a the result obtained is because the reduction in quality is compensated by a simpli ied manufacturing process fo the printing Example A planographic printing forme was prepared in the manner described Example 20 above that support for the reproduction layer consisted of a plastics film a layer thereon had been hardened with diinethylol urea the presence of aluminium The product corresponds to the result of Example Example A zinc plate was by means of a plate with a solution which contained of diaside compound used Examples 1 to o the novolak used in Examples to and of polyvinyl dissolved in dimethyl The layer being by a plate was was further dried by heating for 20 seconds to It then had a thickness of The reproduction material thus produce mayb used for the preparation of a ielief printin It was exposed for minutes to the light of a carbon arc using step but no The reproduction layer then bathing it insufficientOCRQuality

Claims (8)

WHAT IS CLAIMED IS :

1· A process for the production of a light-sensitive reproduction material for the preparation of printing formes suitable for y printing continuous tones* wherein a solution of a quinone dlazide in dimethyl formamide, dimethyl sulphoxlde* 2,2,3 ,3 ,-tetra-fluoroproponol or 2>23,3»4,4»S,5»-octafluoropentanol, which solution contains at least 1*9 per cent by weight of the qulnone diazide and also a resin in the proportion of 2,5 to 100 per cent by weight calculated on the weight of quinone dlazide* the sum of the weights of resin and qulnone dlazide being at least 2.1 per cent by welgh of the solution is applied to a support in such a manner that after drying a dried coating Is obtained having a thickness of 0.4 to 3*0 microns*'

2. A process as claimed in Claim 1» wherein the said solution contains 2.5 to 24 per cent of resin* calculated o the weight of dlazide compound.'

3. A process as claimed in Claim 1, wherein the said solution contains at least 2.2 per cent by weight of an o-naphthoquinone dlazide compound and is applied in such a manner that the resulting dried coating has a ttickness of at least 0.6 micron.

4. A process as claimed in Claim 1* substantially as described herein*

5* . A light-sensitive reproduction material when made by the process material* when made by the process claimed in any one of Claims 1 to 4.

6. A process for the preparation of a printing forme sutiable for printing continuous tones* wherein a light-sensitive reproductio material as claimed in Claim 5 is exposed under a coninuous tone original without ' the use of a screen followed by development in the conventional manner*

7. A process as claimed in Claim 6 substantially as described in any one of th< Examples herein.

8. A printing forme suitable for pri made by the process claimed in Claim 6