CS241578B1 - Light sensitive solution to pre-sensitize offset printing plates - Google Patents

Abstract

Photosensitive solution for presensitization of offset printing plates, characterized in that it contains 0.5 to 50% by weight of C-(4-azidophenyl)-N-phenylnitrone and 0.5 to 50% by weight of aromatic diazide, based on the weight of the polymer substrate. Metacresol-formaldehyde resin or a mixture of metacresol-formaldehyde resin with polymers soluble in water or in basic aqueous solution, preferably with cellulose ethers, is used as the polymer substrate. 2,6-bis(4'-azidobenzal)-4-methylcyclohexanone or 2,6-bis-(4'-azidobenzal)-cyclohexanone is used as the aromatic diazide. The photosensitive solution is applied in an amount of about 2 g/m2 to an anodically oxidized aluminum plate and exposed to a halide discharge lamp. By using an aromatic nitrone with an azido group on the aromatic nucleus as a photosensitive substance, an increase in sensitivity in the blue region of the spectrum is achieved. Another advantage of the proposed system is that when copying the image of the copy master onto a thin photosensitive layer, the resulting latent image is simultaneously visualized.

Description

241578

The service relates to a susceptible solution of the specified pre-sensitization of the pre-set printing plate of a sensitized polymers or polymers, which, when applied in a thin layer on a suitable substrate and dried, can be used to copy the image of the copying pattern.

The principle of the photochemical method of making a copy in a printing reproduction is to record the light information of the copier in a layer sensitized by low molecular weight or semi-light sensitizers. Organic photopolymers, salts of hexavalent chromium, salts of silver, diazo compounds, organic azides, and benzodiazides, nitrons, etc. are used to record light information.

The polymeric substrate used in photochemical reproduction is natural and / or biosynthetic polymers, which, by sensitizing the light sensitive substances, change the physicochemical properties, most often solubility, at the point of radiation radiation. From the environmental point of view, development focuses primarily on water-soluble, light-sensitive layers, respectively. on the layer in which the main component of the developer forms a conduit. In terms of standardization and quality, in particular, pre-sensitized print subscriptions, which are characterized by long-term versatility and machine processing capabilities, are not detrimental to reproductive attenuation properties.

The use of light sensitive nitrons - in photo-chemical reproduction - is disclosed by US Patent Patent. A disadvantage of these systems is that light sources with rich ultraviolet radiation must be used for exposure.

This drawback solves the light-sensitive solution according to the invention, characterized in that it contains from 0.5 to 50% by weight of C- (4-azophenyl) -N-phenylnitrone and from 0.5 to 50% by weight of polymeric substrate. % by weight of aromatic diazide. The polymeric substrate is a methacresol formaldehyde resin, or a mixture of metacresol formaldehyde resin with water soluble polymers or a basic aqueous solution, preferably cellulose ethers. The aromatic diazide used is 2,6-bis (4'-azidobenzal-4-methylcyclohexanone or 2,6-bis (4-azidobenzal) -cyclohexanone. Another advantage of the proposed system is that when copying an image of the copying master into a thin, light sensitive layer, the resulting image is visualized.

A light-sensitive solution containing 6 parts by weight of methacresolformaldehyde resin, 3 parts by weight of C- (4-azidophenyl) -N-phenylnitrone, 60 parts by weight of ethylcellulose and 3l1 parts by weight of acetone is applied to the anodic oxidized aluminum canvas in a centrifuge. 2 g / m2 and dried. The prepared pre-sensitized canvas is contacted by copying a copy of the original from a distance of 1.5 m. Exposure time - 5 minutes. The resulting 1-figure is produced in 0.5% sodium hydroxide solution. EXAMPLE 2 - Light-sensitive solution containing 7 parts by weight of methacresol formaldehyde resin, 3 parts by weight of C- (4-azido-phenyl-N-phenylnitrone, 1 part by weight of 2,6-bis (4'-azidobenzal) of cyclohexanone, 59 parts by weight of methylene chloride and 30 parts by weight of acetone, anodized oxidized aluminum foil is coated in an amount of 1.8 g / m 2 by exposure to a 5,000 W h-allogenide lamp via a copying precursor. A good visible positive image is obtained after induction in 0.5% sodium hydroxide solution Exposure time - 3 ml.

A light sensitive solution of composition as in Example 2, using as the diazide 1 molar part of 2,6-bis (4'-azidobenzal j-4-methyl-cyclohexanone. Exposure to 5000 W halo excellent light quality is obtained after inducing a positive image. Example 1 -a -d 4

The light-sensitive composition of the composition as in Example 2 wherein 2 parts by weight of 2-hydroxypropylcellulose is added to the light sensitive composition. After application of the light-sensitive layer to the anodized oxidized aluminum coating, the exposure was shortened to 2 anines. .

Claims (3)

241578 PREDMET What is claimed is: 1. A light sensitive solution for the presensitization of offset printing plates, characterized in that it contains 0.5 to 50% by weight of C- (4-azidophenyl N-phenylnitrone and 0.5 to 50% by weight of aromatic diazide) to the weight of the polymeric substrate. . 2. A light-sensitive solution according to claim 1, wherein the resin is a resin or a methacresol formaldehyde resin with a water-soluble polymer or a basic aqueous solution, preferably with cellulose ethers. 3. A light sensitive solution according to claim 1, wherein the aromatic di-azide (2,6-bis (4'-azidobenzal) -4-methylcyclohexanone or 2,6-bis (4'-azidobenzene) is used). zal) -cyclohexanone.