DE2061288A1 - Preparing film for high pressure - Google Patents

Description

Badische Anilin- & Soda-Fabrik AG

Our reference: O.Z. 27 223 D / Ot

6700 Ludwigshafen, December 10th, 1970 make-up film for high-pressure printing

The invention relates to a finishing film for high pressure.

Beirr. In order to achieve a good print result, especially in the case of images, letterpress printing processes, it is necessary that full-tone areas and higher halftone values receive more pressure than lighter halftone areas. This is achieved by using a make-up film that is attached under the printing plate or in the elevator i. Like the printing cliché, the make-up film contains a relief-like image. In contrast to the printing cliché, however, the height of the relief depends on the tonal value of the image to be printed. It is greatest for full tone areas, generally between 100 to 150 μm, and practically zero for very small tone values.

In the previously known and mainly used methods, the variable relief height of the dressing film is achieved in different ways, for example by a build-up swelling process (3M dressing), a build-up scattering powder process (Primaton dressing) or a degrading a etching process (MKZ- Finishing). What all these processes have in common is that only a copy of the motif to be printed is produced on the make-up film in the printing machine. The printed film is then treated further depending on the finishing process used.

Furthermore, attempts are known to achieve a finishing for high pressure photomechanically. Included is made by exposing a special photographic film through the carrier film and subsequent overdevelopment corresponding relief received. In addition to the special film, this process also includes a normal photographic one Film necessary for making the dressing. For the her-

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The position of the photomechanical finishing are two prints of the mold closed in the machine. Because of the extremely difficult production of the special film it is not possible to use the photomechanical finishing in practice.

The aim of the invention is to simplify the relatively complicated and cumbersome finishing process. It is It is an object of the invention to produce a make-up film bypassing the pressure. It's another job of the Invention, the relief structure depending on the tone value and to be produced independently of the coloring. The inventive Make-up film should allow better standardization and reproducibility of the make-up.

The object is achieved in a method for producing a finishing film for high pressure, whereby one exposing the photopolymerizable layer of a multilayer film under a negative through the support and the unexposed parts of the photopolymerizable layer including the parts of the Wash the intermediate layer with a solvent from the unexposed side.

The multilayer film is made up of

a) a dimensionally stable transparent to actinic light Carrier,

b) a 5 to 60 µm strong, non-photopolymerizable,

Solvent-soluble and 0.01 to 10 Gew.ft. actinic Light absorbing compounds containing intermediate layer and

c) a 20 to 250 µm strong, photopolymerizable, 0.01 to 10 wt% actinic light absorbing compounds containing layer.

The make-up film according to the invention consists of several layers built up. A carrier that is trans-

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parent plastic film from a thickness of 20 to 250 ^ uir used. Another requirement of this carrier is dimensional stability with respect to the mechanical stresses when printing. As suitable support materials, the above For example, polyester films, polyvinyl chloride or cellulose acetate films have proven to be suitable proven. A polyester film made of polyethylene terephthalate with a thickness of 20 to 250 μm is preferred proven.

On the carrier film there is a layer, called an intermediate layer, of a material that is not photopolymerizable, but soluble in the solvents that {

to wash out the unexposed parts of the photopolymerizable Layer can be used. The intermediate layer expediently has a thickness of 5 to 60 μm.

In the simplest case, the intermediate layer consists of the same material as the photopolymerizable layer, but without photoinitiator and optionally without monomers.

It proves to be particularly advantageous if the intermediate layer for actinic light about the same optical properties with regard to optical density or transmission for UV radiation, as the photopolymerizable layer has. This is achieved by the Interlayer the same additions from 0.01 to 10% by weight, based on the total weight of the interlayer, of actinic Contains light absorbing compounds,

The photopolymerizable layer has a basic composition as for example in US Pat. No. 2,760 or British Pat. No. 1,173,043 for photopolymer layers to be discribed.

It consists of a polymeric base material, monomers with olefinically unsaturated double bonds, photoinitiators and low levels of thermal polymerization inhibitors.

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Vinyl polymers such as polyvinyl chloride, vinylidene chloride polymers and copolymers may be mentioned as polymeric base materials from vinyl chloride and vinyl esters of monocarboxylic acids and / or vinyl alcohol, polymers from predominant amounts of olefinically unsaturated carboxylic acids with 3 to 5 carbon atoms and / or their esters and / or amides, e.g. of acrylic acid, methacrylic acid and their esters with alkanols with 1 up to 12 carbon atoms, such as acrylamide or methacrylamide. Also polymers based on styrene or vinyl esters of Monocarboxylic acids having 2 to 11 carbon atoms such as vinyl acetate and vinyl chloroacetate are suitable. Be mentioned also the polymers based on methacrylic and acrylic acid esters of aliphatic diols and polyols, such as ethylene glycol, 1, * 4-butanediol or glycerin. Finally you can too soluble cellulose derivatives, polyesters and polyethers can be used.

Particularly suitable polymers are the linear synthetic polyamides with recurring amide groups in the main molecular chain, which are soluble in customary organic and, in particular, alcoholic solvents. From them mixed polyamides, which are in common solvents or solvent mixtures, such as in lower aliphatic alcohols, alcohol-water mixtures or mixtures of alcohols with other solvents, jg.B. Beneol-alcohol-water mixtures, or soluble in ketones, ethers or aromatic hydrocarbons, are preferred. These are eB mixed polyamides which have been prepared in the usual way by polycondensation or polymerization, eB activated anionic polymerization, from two or more lactams with 5 to 13 ring members. Such lactams are, for example, pyrrolidone, caprolactam, önantholactam, capryllactam, laurolactam or corresponding C-B-substituted lactams, such as C-methyl- ε-caprolactam, ε-ethyl-ε-caprolactam or S- ethylönanthlactam. Instead of the lactams, the aminocarboxylic acids on which they are based may have been polycondensed. Other suitable mixed polyamides are polycondensation products from salts of the diamine / dicarboxylic acid type, which are composed of at least three polamide-forming starting materials

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... materials have been produced. Dicarboxylic acids or diamines suitable for this purpose are preferably aliphatic dicarboxylic acids with 4 to 20 carbon atoms, such as adipic acid, suberic acid, sebacic acid, dodecanedicarboxylic acid, and corresponding substitution products, such as o (, oC-diethyladipic acid, oC-ethylkorkic acid, heptadecanedicarboxylic acid-1, 1,8 or 1,8-heptadecanedicarboxylic acid , 9 or mixtures thereof as well as dicarboxylic acids containing aliphatic or aromatic ring systems.Suitable diamines are particularly aliphatic or cycloaliphatic diamines with 2 primary and / or secondary amino groups, in particular with 4 to 20 carbon atoms, such as pentamethylene diamine, hexamethylene diamine, heptamethylene diamine, octamethylene diamine or C- and / or N-substituted derivatives of these amines, etc., such as N-methyl-N-ethyl-hexamethylenediamine, l, 6-diamino-4-methylhexane, ^, ^ '- diaminodicyclohexylmethane or 4,4'-Diaaiinodicyclohexylpropan further aromatic diamines such as m-phenylenediamine, m-xylylenediamine or 4,4'-diaminodiphenyl! »than, with all Starting materials, the bridge members between the two carboxylic acid groups or amino groups can also be interrupted by heteroatoms, for example oxygen, nitrogen or sulfur atoms. Particularly suitable mixed polyamides are those which have been produced by co-condensation of a mixture of one or more lactams, in particular caprolaotam, and at least one dicartonic acid / diamine salt, for example from g-caprolactam, hexamethylene diammonium adipate and 4,4'-diaminodicyclohexyl methane adipate. "

Compounds with photopolymerizable monomers are used olefinically unsaturated double bonds in frag ·, which see below at least JJQ up to 50 percent by weight with the Polymers are compatible. The majority of the monomers used, 70 to 100 percent by weight of the total monomers used, should be more al * contain a photopolymerizable olefinic double bond. Suitable monomers with at least two polymerizable olefinic double bonds, which are particularly suitable for Mixtures with soluble linear polyamides are favorable, are those that contain amide groups in addition to the double bonds,

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such as amides derived from acrylic and / or methacrylic acid. The alkylene-bis- (meth) acrylamides, such as methylene-bis-acrylamide, methylene-bis-methacrylamide, the bis-acrylamides, bis-methacrylamides of aliphatic, cycloaliphatic and aromatic di- or polyamines with 2 to 12 carbon atoms, such as of ethylenediamine, may be mentioned , Propylenediamine, butylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, xylylenediamine and also polyamines and other diamines, which can also be branched and interrupted by heteroatoms such as oxygen, nitrogen or sulfur atoms. Dieters composed of 1 mole of an aliphatic diol or polyol and 2 moles of N-methylol- (meth) acrylamide are very suitable. Also suitable are photopolymerizable monomers which, optionally in addition to amide groups, also contain urethane or urea groups, such as the reaction products of mono- (meth) acrylates of aliphatic diols with diisocyanates or the corresponding reaction products of mono- (meth) acrylamides of diamines with diisocyanates . Of nitrogen-containing monomers, triacryloyl perhydrotriazine or triallyl cyanurate are also suitable. The di-, tri- or tetra-acrylates or methacrylates of di- or polyhydric alcohols and phenols, for example di- and triethylene glycol di (meth) acrylate, are also suitable. However, the use of bifunctional or polyfunctional polymerizable monomers is not limited to the selection mentioned above. It also includes other monomers with at least two polymerizable double bonds, provided that they are at least 20 to 50 % compatible with the copolyamides mentioned, which can easily be determined by a simple manual experiment.

In addition to the monomers with more than one polymerizable olefinic double bond, monomers with only one polymerizable olefinic double bond, such as aromatic hydrocarbons, e.g. styrene or vinyl toluene, acrylamide, can also be used in a minor amount, preferably in an amount of less than 30 percent by weight of the total amount of monomers. or methacrylamides and their substitution products, such as N-methylol (meth) acrylamide or their ethers or esters or monoesters of olefinically unsaturated carboxylic acids having 3 to 5 carbon atoms

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and aliphatic di- or polyols, e.g. mono (meth) acrylates of ethylene glycol, diethylene glycol, triethylene glycol, glycerine, 1,1,1-trimethylolpropane or Ι, Ί-butanediol. For the appropriate The above-mentioned features apply to the selection, the selection also depends on the type of use of the light-sensitive or hardenable mixtures.

Contain very suitable photopolymerizable or curable mixtures in a largely uniform mixture 10 to 50 and in particular 20 to 10 percent by weight of monomers and 90 to 50 and in particular 80 to 60 percent by weight of solid polymers, such as soluble polyamides. Preferred mixtures are solid and are Not sticky even when heated to higher temperatures, e.g. 50 to 60 ° C.

Suitable photoinitiators are above all compounds which decompose into free radicals under the action of light or radiation start the polymerization of the monomers, for example vicinal ketaldonyl compounds, such as diacetyl, benzil; o (-Ketaldonylalkoho-Ie, like benzoin; Acyloin ethers, such as benzoin methyl ether or benzoin isopropyl ether, o (-substituted aromatic acyloins, such as OC -methylbenzoin. The photoinitiators are used in the usual amounts, expediently in amounts of 0.01 to 10 percent by weight, preferably in amounts of 0.01 to 3 percent by weight, based on the total mixture is used. |

Suitable polymerization inhibitors are the usual ones for prevention a thermal polymerization used, for example hydroquinone, p-methoxyphenol, p-quinone, copper-I-chloride, Methylene blue, ß-naphthol, phenols, salts of N-nitrosocyclohexylhydroxylamine i.a. * The polymerization inhibitors are usually used in amounts of 0.01 to 2.0 percent by weight, preferably in amounts of 0.05 to 0.5 percent by weight, based on the total mixture, used.

The thickness of the photopolymerizable layer is zweckir.äßigerweise 20 to 250 / To, preferably l \ 0 to 150 ^ order. By adding compounds that are light in the actinic

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Absorb area, the photopolymerizable layer has the optimal optical density, this can be maintained by adding compounds which absorb particularly in the ultraviolet part of the spectrum in an amount of 0.01 to 10 Gew.J5, based on the total weight of the photopolymerizable Layer.

It may be useful that the carrier Serving plastic film for better adhesion of the applied layers additionally provided with an adhesion promoter is. Electrostatically pretreated polyethylene films or adhesive varnishes are expediently applied as adhesion promoters Based on polyesters or polyurethanes used.

The actual finishing for the letterpress is made by making the photopolymerizable layer of the multilayer Film, built up from the three layers a), b) and c), under a negative through the carrier film exposed and the unexposed parts of the photopolymerizable layer including that located underneath Wash out parts of the intermediate layer with a solvent from the unexposed side.

According to an advantageous embodiment, the photopolymerizable Layer exposed for example through a rasterized negative through the carrier film.

Subsequent washing with a solvent from the unexposed side gives a relief, its The height of the optical density of the negative is largely proportional.

A photopolymerizable layer with a thickness of 20 to 250 μm, for example, has a composition of 50 to 90% by weight. a mixed polyamide, based on a mixture of hexamethylenediamine adipate, 4,4-diaminodicyclohexylmethane adipate and C -caprolactam, 10 to 50% by weight of one or more photopolymerizable crosslinking acrylic acid derivatives

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"derivatives, such as N-methylol acrylamide, m-xylylenebisacrylamide, Triäthylenglykoldiacrylat or diether of ethylene glycol and N-methylolacrylamide, and additions of 0.5 to 5 wt,% photoinitiator, such as CC-Methylolbenzoinniethyläther, benzoin isopropyl ether, from 0.1 to 1 wt. % thermal inhibitor, such as sodium N-nitrosocyclohexylhydroxylamine, p-methoxyphenol and optionally additives such as ethylene glycol or plasticizers.

To achieve an optimal optical density, the photopolymer layer contains an addition of compounds for light absorption in the actinic range, which should of course be photochemically and chemically inactive and in the crosslinking reaction ' are not allowed to intervene.

The exposure is generally done by area light, The usual larapen with a serve as radiation sources high proportion of actinic light, such as mercury vapor lamps, xenon lamps and fluorescent tubes. Under actinic light becomes near UV light with a wavelength of 300 to 400 μm Understood.

In order to achieve tonwertabhängige relief height, it is necessary that the passed through the negative rastered light beams overlap good, that is, the light beam formed by i the grid to be converted into a very homogeneous light front. This is achieved on the one hand by using area light. This effect is reinforced by the measure that the negative is kept at a certain distance from the photopolymerizable layer during exposure. The constant distance is achieved by exposure from the rear side, since in this case the carrier film, which acts as a "spacer", is located between the negative and the photopolymerizable layer.

In order to achieve a relief height that is dependent on the tone value, a sufficiently high optical density of the photopolymerizable layer for the actinic radiation is required. With a

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high optical density it is possible to use a steep gradient the light intensity within the photopolymerizable layer. From the decrease in the intensity of the actinic A reproducible photo-crosslinking and thus the relief height of the finishing film depends on the light within the photopolymer layer away.

The higher the optical density of the layer, the better the reproducibility and the smaller the minor error deviations in the relief height. On the other hand, optical densities that are too high require an exposure time that is unacceptably long in practice. One is therefore forced to choose a compromise.

The most favorable optical densities are achieved by adding compounds, in particular in the ultraviolet part of the spectrum and make the radiation in this area photochemically ineffective.

For example, a large number of customary UV stabilizers for plastics, such as those in the articles by RA Coleman, JA Weicksel, Modem Plastics, Volume 36, No. 12, pages 117 to 121 and 198 to 200 (1959) and H. Gysling and HJ Heller, Kunststoffe £ 1 (I96I) pages 13 to 17 are described. Suitable compounds are, for example, o-hydroxybenzophenones or bisphenols which are substituted in positions adjacent to the hydroxy groups, such as 2,2'-dihydroxy - ^ - methoxybenzophenone or bis (2-hydroxy-3-tert.-butyl-5-methyl- phenyl) methane. Aromatic di- and trinitro compounds, such as 2,4-dinitrophenol and soluble dyes with a heavy metal atom bound in a complex, such as are generally summarized in Color Index under the term "Solvent Dyes", are very suitable. The metal complex dyes are preferably 1: 1 or 1: 2 complexes of azo or azomethine dyes with 0-carboxy-o ¹ -hydroxy or o-amino-o'-hydroxy groups and in particular ο, ο'-dihydroxy groups . Chromium and cobalt are particularly suitable as complex metals. Suitable dyes are described, for example, in German patents 1,226,727 and 1,263,947. Than phthalocyanines are

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preferably to mention the copper-containing compounds. Suitable Dyes are specified in particular in German patent application P 19 05 012.5.

UV-absorbing inorganic pigments, vjie Iron oxide, chromium oxide, titanium dioxide, etc. can be used.

The amount of additive is aimed at UV absorbing compounds is based on its extinction coefficient, the layer thickness and it depends on the tone values for which another one Finishing is desirable. In general, the addition is 0.01 to 10 wt. Ji, based on the total weight of the respective Layer. An addition of 0.1 to 1 wt. Si is preferred. With layer thicknesses of 100 .mu.m and optical densities between 1 and 2, the associated exposure times are then between 2, for example when using fluorescent tubes up to 5 minutes.

A prerequisite for a good quality of the print is that the light areas of an image from a tone value of 0 to about 30 % receive no finishing. This requires that during exposure through the negative , the light intensity that falls through the shade values between 0 and about 30% in the photopolymerizable layer must no longer trigger photopolymerization or relief formation.

This requirement can be met by the invention multilayer structure of the finishing film. The non-photopolymerizable intermediate layer and the actual photopolymerizable one Layer.

The intermediate layer has a thickness of 5 to 60 μm, is not photopolymerizable and has approximately the same optical properties, in particular with regard to optical density, as the photopolymer layer % correspond to, are absorbed in the intermediate layer and can no longer trigger any crosslinking reaction in the photopolymerizable layer. 209826/0828

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To achieve an exact reproducibility of the relief heights from the optical density of the film negative, it is advisable to to maintain the optimum distance between the negative and the photopolymer layer.

In the simplest case, the intermediate layer consists of the same Mixture like the actual photopolymer layer with the omission of the photoinitiator. If necessary, are in the intermediate layer also does not contain monomers contained in the photopolymer layer. The intermediate layer has a preferred thickness of 15 to 30 μm. The thickness of the intermediate layer depends on the tone values for which a finish is to be obtained.

Optical properties of the intermediate layer and the photopolymerizable layer which are as identical as possible are achieved by the same Additions of absorbent compounds achieved.

As an exemplary composition for an intermediate layer a mixed polyamide based on approximately equal parts hexamethylenediamine adipate, ^, ^ '- diaminodicyclohexylmethane adipate and ^ -Caprolactam, the 2, Ί-ϋίηίΐΓο-phenol or Zapponechtschwarz and possibly also the diether of ethylene glycol and methylol acrylamide, N-methylolacrylamide, ethylene glycol, sodium N-nitrosocyclohexylhydroxylamine can be added.

About the same composition of the layer thickness as the photopolymer layer has the advantage that the intermediate layer can be removed with the same solvent without any difficulty when developing the relief.

After exposure, the unexposed parts of the photopolymerizable layer are washed out by solvents. Lower aliphatic alcohols, preferably ethanol / water in a molar ratio of Ί: 1, have proven to be suitable as solvents proven.

The intermediate layer is in the places without photo-crosslinking or relief formation according to the lower tonal values,

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which should not receive any dressing, while with higher ones Tones the soluble underlayer through the overlying photopolymerized material against the washout solvent is protected.

With the help of the finishing film according to the invention, excellent Printing results achieved. The finishing process is largely simplified and saves considerable time. The printer is given a correct tonal corrective sheet, which is used to produce a finished printing form or form. a pressure is bypassed. The preparation foil, starting from the film negative, makes time-consuming and difficult to perform | Manual corrections are unnecessary and an improved standardization of the printing process is achieved.

In Pig. 1 is the curve-wise relationship between tone value and photopolymerized layer thickness or relief height shown, with tone values up to 20 not receiving any finishing in this example.

If necessary, the finishing film can also be produced without an intermediate layer. You then get one Relief height depending on the tone value, but must be how FIG. 2 shows, and is also apparent from Example 3, that if necessary the finishing film can be corrected for lower tonal values, I.

example 1

A 125 / um thick polyester film is a 25 / um thick Layer of the following composition applied:

89 parts of a mixed polyamide from approximately equal parts of hexamethylenediamine adipate, ^, M'-diaminodicyclohexylmethane adipate and ε-caprolactam, 27 parts of the diether from 1 mole of ethylene glycol and 2 mol of N-methylolacrylamide, 0.2 part of sodium salt of N-nitrosocyclohexy / hydroxylamine and 0.35 parts of Zapponechtschwarz RE, 1: 2 chromium-Miechkomplex of the azo dyes from the components

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<4-nitro-2-aminophenol, 5 ~ mitro-2-aminophenol and ß-naphthol. On top of this layer is then an 80 .mu.m thick layer of the same composition with an addition of 2 parts 0 (-Methylolbenzoinmetnyläther laminated. The film obtained is exposed for 2 minutes through the carrier film using a gray wedge. By exposure in a vacuum frame a close contact between the carrier film and the grid gray wedge is guaranteed. Fluorescent tubes also serve as the light source high UV component, which are located at a distance of 3 cm above the film. Then the unpolymerized portion is Washed out from the front with ethanol / H2 0 4: 1. After exposure and washing out, the dependence of the polymerized layer thickness on the one shown in Fig. 1 is obtained Tonal value of the film. A sample of this film, which is tested in a practical test as a make-up film, gives excellent results Results.

Example 2

On a 75 u thick polyester carrier film, two Layers applied:

A 25 / µm thick intermediate layer consisting of 100 parts of the in Example 1 described mixed polyamides, 0.2 parts of Na salt des N-nitrosocyclohexy / hydroxylamine and 0.2 part of 2,4-dinitrophenol. A 75 / µm thick photopolymerizable layer as follows Composition is laminated on top: 100 parts of the same Mixed polyamides, 8 parts of triethylene glycol bisacryliamide, 20 parts m-xylylene bisacrylamide, 30 parts N-methylolacrylamide, 0.1 part Na salt of N-nitrosocyolohexy / hydroxylamine and 0.3 part of 2,4-dinitrophenol. The exposure and washing were carried out as described in Example 1. You get a dependency of polymerized layer thicknesses of the tonal value of the film similar to FIG. 1. A printing test with this make-up film also shows excellent results.

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Example 3

A 100 u photopolymerizable film is placed on a 125 / U thick polyester film Layer of the following composition applied:

6h parts of the mixed polyamide described in Example 1, 27 parts of the diether of ethylene glycol and N-methylolacrylamide, 2 parts of OC-methylolbenzoin methyl ether, 8 parts of iithylene glycol, 0.2 part of sodium salt of N-nitrosocyclohexylhydroxylamine and 0.3 part of Zapponechtschwarz RE. The film obtained as described in Example 1 2 minutes exposed through a raster gray wedge and then excluded from the front t

to wash. A relief is obtained, the height of which depends on the tonal value of the film (Fig. 2). A printing test with this film shows satisfactory results. However, the light tones of the print (tone value 0 to 20) are still a little too pronounced.

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Claims (2)

- 16 - 0.2. 27 223 Claims fly Process for the production of a finishing film for letterpress printing, characterized in that the photopolymerizable layer of a multilayer film is exposed under a negative through the support and the unexposed portions of the photopolymerizable layer including the parts of the intermediate layer located underneath it is removed from the unexposed layer with a solvent Washes out the side. 2. Use of a multi-layer film as a finishing film for high pressure, built up from a) a dimensionally stable transparent to actinic light Carrier, b) a 5 to 60 um strong, non-photopolymerizable, Solvent-soluble and 0.01 to 10% by weight * containing actinic light-absorbing compounds Intermediate layer and c) a 20 to 250, to absorbent strong, 0.01 to 10 wt.% actinic light containing compounds photopolymerizable layer. Badische Anilin- & Soda-Fabrik AG drawing. 209826/0828