CS200036B1 - Preparation method of negative working lightsensitive layer for offsetprinting plate - Google Patents

Description

The present invention is directed to a process for preparing a negative-working light-sensitive layer for preparing an offset printing press.

Image reproduction in printing techniques is based on the distribution of the polton image into tiny microelements that are fixed in the form of a copy onto the printing plate. The final copy is printed on paper or other printed material from the copy thus obtained after the ink has been rolled in the printing machine. The image on the copy is created by copying the negative into a photosensitive layer, usually applied on an aluminum support. Upon irradiation with ultraviolet radiation, the photosensitive polymer layer crosslinks at the radiation impact points, thereby rendering the insoluble breast ordinary solvents. By dissolving the non-irradiated areas a copy of the original is obtained on an aluminum support.

Currently, there are many proposed processes for the preparation of a light-sensitive layer, from which practical applications have been obtained mainly from substances based on diazides, diazoketones, derivatives of scoric acid and substituted stilbones. The vast majority of the other systems described have been applied mainly due to the difficulty of synthesis and the lack of photosensibility properties.

The copied image formation according to the invention is based on the cross-linking of linear macromolecules of natural or synthetic rubber in the presence of 4,4'-dinitro-1,3-diphenyl-1-butene as a resistant. Said substance undergoes a reduction in the environment which is capable of providing a hydrogen radical under the influence of ultraviolet radiation! via nitro groups at the same time

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the formation of free radicals on the polymer strand. The radicals e thus formed either recombine with each other or are screened over the bridging agent bridge. Reduction of the hydroxylamine and aminoacids formed may result in a system characterized by ea etnoeles of antloxidizing agents, which greatly prolongs the yellowish layer of the evetleeite layer relative to the ethoxylate. The photosensitive properties of the system can be modified by the addition of ultraviolet sensitizers, preferably bonzophenone, anthrone and Michler ketone in an amount of 0.1 to 5% by weight.

The advantage of the proposed process is the ease of preparation of the photosensitive solution, the relatively low cost and simple handling. Commonly used equipment of printing plants can be used for coating. The proposed avto-aloof copying door aa is characterized by large oetroal drawings, high mechanical strength of the obtained image and simple development of the process. A prime advantage of the system is that the light-sensitive layer extends the life-long eve by cutting off the dark reacols.

The method of steaming the right copy layer

The base composition aa prepared as a solution of polymeric substance and 4,4 ' -dinitro-1,1-diphenyl-1-butene with a suitable coneentreil. The prepared aa nanaale thus prepared on anodised aluminum sheet and the obtained film aa is allowed to extend. The film then copies the glow to the film and. The copied image aa produces a suitable developer, and copies aa adjust to the fire of Saliie's process. In Salami, you will come up with examples, without applauding these exclusive ones.

Example 1

The stock solution aa is prepared by treating 2% by weight of a solution of chloroprene, natural, butadiene or butadiene-styrene rubber in a chlorinated hydrocarbon and 4,4 ' -dinitro-1,3-diphenyl-1-butene, 2% by weight of the polymer. The so prepared rocaille aa is applied to an aluminum anodized surface in a horizontal centrifuge at 50 rpm. The coated plate is dried at room temperature for 1/2 hour, and connected with a negative reproductive substrate, and the image is copied in a standard 3000 V ultraviolet source, 4 min exposure time. The copied image aa is produced by a mixture of chlorinated and aromatic hydrocarbons.

Example 2

The process as in Example 1 and adding 0.5 wt% of an ultraviolet sensitizer, for example bonzophenone, Mlohler ketone, sodium to the aa base solution. Addition of the sensitizer shortened the exposure time to 45 to 90 eeconds.

Claims (1)

A method of preparing a negatively-functioning light-sensitive layer for an offset printing screen by ultraviolet radiation, characterized by the fact that image recording is generated 200 030 by cross-linking the linear macromolecules of rubbers radically resulting from the reduction of nitroaccharins, 4,4 ' -dinitro-1,3-diphenyl-1-butane on the polymer chain and in the presence of ultraviolet sensitizers such as benzophenone, anthrone and Michler ketone , 1 to 5% by weight.