DE832546C - Light-sensitive layers for reproduction technology - Google Patents

Description

In reproduction technology one uses for Coating of the metal or stone slabs or other supports colloids of various kinds. The in the presence of light-sensitive substances, such as. B. of salts of chromic acid, by the action of light, especially in their solubility (so-called hardening). One uses for coating mainly certain natural substances such as gum arabic, isinglass, gelatin, protein,

ίο which however have the disadvantage that they do not can always be preserved in the same quality and therefore reproduction materials deliver, which are subject to certain fluctuations in their properties. In addition, the named colloids are easily attacked by microorganisms.

The use of synthetic colloids as coating materials for Production purposes have been proposed, but the number of compounds which can be used in practice is very large small amount. Polyvinyl alcohol has become more widespread, see for example in the light with salts of chromic acid and with certain diazo compounds, such as those mentioned, inter alia. in the German patent specification 596731 have been described, harden as j lets. On the other hand, it is with azido compounds, which are technically very important because they are produced with them Layers on metal can be stored without change, in the usual way for hardeners Quantities applied not to achieve photocuring of polyvinyl alcohol. Also gum arabic and isinglass give in the light curing with azido compounds, as they are z. B. in the French No. 886 716 are unsatisfactory Results.

It has now been found that one can use polymers Acrylic acid amides with good success as coating materials use for reproduction purposes

can. Since these substances are easily produced with a constant quality let the layers produced with them be uniform at all times. In addition to the polyacrylic acid amide itself, those on nitrogen, for example by alkyl groups, are also substituted compounds useful. Copolymers of acrylic acid amides are also used other vinyl compounds, for example vinyl acetate, usable. The polymerization products of the homologues the aforementioned acrylic acid amides, e.g. B. Polymethacrylsäurcamide use.

The polyacrylic acid amides can also be used as a mixture with other soluble colloids. The higher viscosity products are particularly suitable for the coating.

Chromates, Use diazo compounds or azides. The layers are of particular importance which azides contain, as these are, as mentioned. on metal printing plates made of zinc or aluminum last a very long time without losing their ability to copy. This makes it possible to produce coated, Bringing copyable reproduction material on the market, while the printer has so far been compelled to do so was to coat his printing plates himself shortly before use.

Sensitizers, hardeners or other auxiliaries can also be added to the layers will.

The coating materials to be used according to the invention are mostly water-soluble. Consequently the creation of the photosensitive layer is very simple: the photosensitive substance is incorporated into an aqueous solution of the polyacrylic acid amide compound; which then to the Layer support is applied in a known manner and dried. Also the development of the enclosed Layers can be carried out very easily due to the water solubility of the layer. If water solubility is lacking, aqueous-alcoholic or, if necessary, alcoholic is used Solutions.

The present invention has relevance, for example for the production of master copies and printing forms for flat and offset printing, the production of gravure forms and rubber printing.

The preparation of the polymeric acrylic acid amides to be used according to the invention and their Substitution products and copolymers made therefrom are known and are described, for example in the French patent specification 898 577 and in the "Journal of the American Chemical Society" 69 (1947), pp. 1911-1914 (Hatchford and Fisher).

example 1

An aqueous solution containing 50/0 of a highly viscous polymerization product of N-dimethylacrylamide and 0.50 / 0 is applied to an aluminum foil one by condensation of 1 mole of p-diazodiphenylamine sulfate and 1 mol of formaldehyde in 80% sulfuric acid contains, in the usual way, for. B. using a slingshot, applied and then at moderately heat dried. Exposure is made under a negative, the film is rinsed off with water, whereby the areas of the photosensitive layer not struck by the light are dissolved away. and stains the hardened colloid with a dilute aqueous methylene blue solution. Man receives a blue positive image.

Instead of the aluminum foil, other metal foils can also be used as a layer carrier, as well as plastic films, glass, paper, fabric, etc. The images obtained can, for example can be used as reflective or transparent images or as master copies. One can if desired The solutions used for the coating also include dyes, sensitizers, stabilizing agents Add additives, etc.

Example2

The procedure is as in Example 1, but exposed under a positive. After showering the exposed The film is dried with water and the negative colloid image in a manner known per se by covering with a thin layer of varnish, for which an alcoholic varnish can be used, Rubbing in with bold paint and subsequent stripping into a ready-to-print positive printing form converted.

Example 3

With an aqueous solution which 5Ό / 0 of a poly-N-diethylacrylic acid camids (K value 70) and 0.50 / 0 ammonium dichromate, a zinc plate is coated in the usual way. To drying is exposed under a positive, the non-hardened parts are treated by treatment dissolved with cold water and the film is, as indicated in Example 2, in a known manner in converted to a positive pressure plate.

Example 4

With a 50 / o aqueous solution of polyacrylic acid having a K value 80, which further contains ⁰ ° j5 / o 4, 4'-diazidostilbene-2, 2'-disulfosaures sodium, is a film of a copolymer of vinyl chloride and vinyl acetate in a known Way coated on one side and dried. It is exposed under a negative original, washed with cold water, stained with a 40% aqueous solution of Sirius light blue G (Schultz,. Dye tables, 7th edition, supplementary volume. I, 1934, p. 131) at room temperature and obtained such a blue positive tanning pattern.

Example 5

In 100 parts of a 50% solution of a copolymer from 80 parts of acrylic acid amide and 20 parts of vinyl acetate in 2oOOigem aqueous Alcohol is 0.5 parts of 4,4'-diazidostilbene

2, 2'-disulfonic acid sodium and 0.5 part eosin dissolved, and the solution is anodized in a spinner on an aluminum printing plate with Surface applied.

The dried plate is exposed to light under a positive template and developed with water, whereby the colloid layer is removed from the areas not struck by the light. After the repeated The plate is dried with an alcoholic varnish and then with bold paint rubbed in. Then remove the ones that are still on the plate and hardened by the light Make the colloid layer with water and a brush. You get a positive printing form for flat or offset printing. If desired, the printing plate can be removed prior to application etch the paint in a known manner, for. B. by means of a concentrated solution of ferric chloride.

Claims (1)

Claim: Light-sensitive layers for ^ reproductive technology, characterized in that polyacrylamide, its homologues or substituted on nitrogen for their preparation Derivatives and copolymers containing these compounds can be used. θ 3234 2.