SU542167A1 - Method for making photopolymer printing plates - Google Patents

Description

(54) METHOD FOR MAKING PHOTOPOLYMERIC PRINTING FORMS

one

The invention relates to the field of izgotovolshe print forms and can be used in the printing industry.

Known methods for the manufacture of printed forms include the following operations: mounting a negative, assembling a form, filling a form with a composition, double-sided oblagging, disassembling a form, leaching out the whitespace elements, re-irradiating the resulting printed form.

A disadvantage of the known methods of making printing plates is the increased stickiness of the whitespace elements.

In order to improve the quality of printing plates, a method is proposed in which re-irradiation is performed under a layer of liquid chemically indifferent to the material of the polymerized composition.

For the manufacture of printing forms, the following operations are performed:

- assembly of a high contrast photographic negative on a glass plate and assembly of a mold consisting of two glass plates

and growth frame;

-filling the collected mold with a liquid photo-polymerisable composition;

-two-sided hemming (simultaneous or alternate);

- disassembly of the cassette and the appearance of the mold by solvent; The printing plate can be produced using all known methods, for example, by solvent exposure, using the so-called air knife, sucking the unstructured liquid photopolymerizable composition with whitespace elements, soaking the form with various absorbing materials, etc.

- repeated irradiation of the printed form under a layer of liquid.

The liquid used is various solvents or solutions that do not destroy the unstructured regions of the developed forms; non-extracting or weakly extracting polymerization components and photoinitiator from the gel layer; well transmissive actinic radiation and effectively retarding thermal and slightly inhibiting the process of radical photopolymerization.

The most suitable protective liquid is water. It is desirable that the layer of protective fluid was at least 50 mm. Using

For pre-exposure sources that produce short-wave UV-radiation (X4250 nm), it is sometimes advisable to use as a protective fluid solutions of the mineral salts KNO, CuSO (., GO ,, etc., as well as dyes (methylene carbon, etc.) The use of solutions of these compounds makes it possible to isolate the acoustic region of the spectrum of radiation and absorb the other of the area of the radiation spectrum of the light source.

Photopolymerizable compositions used in the proposed method include polymerization-capable components with an average function of ionicity 2 and a photoinigator. Photopolymerizable compositions can also contain fillers (of organic or nonorganic origin), dyes, antioxidants, and other targeted additives.

Example 1. A liquid composition was prepared comprising, by weight.h. :

О; Ш1одие1иленпшкольклелининфтфалат

(polyester PN-32) 100.01

Dimethacrylic zirr trililengkkol (polyether TGM-3) 15.0

No processing

Extra charge

Additional h-treatment with 1% NaOH

Additional eco-liquid alcohol treatment in one mixture (1: 1)

Additional exposure with protective liquid

 rt

.

Styrene25.0Metacrzyuva Acid15.0

Benzoin methyl ester1,0

The finished composition was inserted into a mold consisting of two plane-parallel glass plates, a growth frame of rectangular shape with internal dimensions of 300x420 mm and a thickness of 1.75 mm, as well as a pressure device. A high-contrast dashed negative was mounted on the inner surface of the glass plate. The cassette assembled and filled with the composition was irradiated under a panel of L-UF-80 lamps at a distance of 80 mm in the flow from the negative side and 1 minute from the opposite side (from the substrate side). By the end of the irradiation, the mold was disassembled and the form was revealed by washing with conductive water for 1 clay. The printing form had a total thickness of 1.75 mm and a height of printing elements of 0.8 mm.

The stickiness of white spots was determined by a three-point system (sticky, weak-sticky, sticky-free).

The data are given in table. one.

Table 1

sticky

sticky

slightly sticky

slightly sticky

no stickiness

water

water +

f5% CuSO is not sticky

water

 5% KNO, no stickiness

kerosene is slightly sticky

TI p and m e r 2. Prepared a number of compositions according to table. 2. Compound fluids were poured into the mold and irradiated as described in Example 1. The irradiation modes and test results are given in the I table. 2

Using the proposed method

It is necessary to improve the quality of printing forms by getting 1 forms with non-whiteness of space elements and eliminating overheating of the material forks at the bottom of the plate, reducing the cost of manufacturing printing forms through the use of cheaper ones (table materials 2. Table 2).