DK144838B - PROCEDURE FOR MANUFACTURING PRINT FORMS OR MATALLIC ESSAY PICTURES - Google Patents

Description

(19) DENMARK (¾)

| J | (12) PUBLICATION ON 144838 B

DIRECTORATE OF THE PATENT AND TRADEMARKET SYSTEM

(21) Application No. 2378/74 (51) IntCI.® β 03 0 13/26 (22) Submission day 1 · ®aj 1 974 (24) Race day 1. May 1974 (41) Aim. available Nov. 3 1974 (44) Presented 14 Jun. 1982 (86) International application no.

(86) International filing day (85) Continuation day (62) Application number -

(30) Priority May 2, 1973 * 2322046, DE

(71) Applicant HOECHST AKTIENGESELLSCHAFT * 6230 Frankfurt, DE.

(72) Inventor Erwin Lind, DE: Franz Freimuth, DE.

(74) Associate Engineer Hofman-Bang & Bout ard.

(54) Process for making printing molds or metallic etch = feeder.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method of producing printing or metallic etching images by electrophotographic or electrographic means, which is of the kind set forth in the preamble of claim 1.

Methods for producing printing molds by electrophotographic fish are known. Thus, in German Patent No. 974,162, such a method for producing lithographic printing plates O of coated paper is proposed by coating the surface of an electrically conductive, moisture-resistant paper film with a layer formed by a photoconductor suspended. in a dielectric, tn 2 U4 838 film-forming carrier, which is illuminated image-wise and elicited with a fat-assuming powder. The places of the induced pressure storm. that is not to be printed is then rendered hydrophilic. This is done by fixing the powder by heating on the photoconductive layer such that the powder melts as far as possible throughout the photoconductive layer, or by pressing the powder into the photoconductive layer, or by providing the powder image with a thin coating of a material serving as a solvent for the photoconductive layer to ensure adequate adhesion. The solvent is then evaporated by heat application. The non-imaging sites are then, by an impregnation process, transformed into a hydrophilic material, at which conversion the fixed powder image must remain unaffected.

In the presence of a hydrophilic layer applied under the photoconductor layer and in the case that the photoconductive layer consists of a readily removable substance, the photoconductive coating can also be removed at the non-imaging locations.

Such a method is only suitable for paper printing plates which are known in connection with low printing sizes and poor lithographic quality. It is necessary to fasten the powder by heat fixation, to apply pressure or to use dissolving liquids and possibly additional heat, which further makes the process disadvantageous due to the time consumption and the increased apparatus supply.

In addition, German Patent Specification No. 1,117,391 is also known for the preparation of printing forms for the use of photoconductive, organic compounds in the layers of electrophotographic copying materials. These have a carrier suitable for printing purposes. The photoconductive layer consists of a monomolecular photoconductor and high molecular weight alkali soluble substances. It is charged in the usual way, illuminated and developed with colored resin powder. The resin powder is fixed by heating to 100 to 250 ° C, then the layer is treated with an alkaline solution, whereby the non-imaging layers are removed by dissolution, and a full adherent form is formed. However, although this method is proposed for foils of metals, paper or plastics, as accurate image reproduction as possible is not ensured, because a thermal fixation of the powder image cannot completely exclude a dimensional change. In addition, the systematic procurement for the implementation of the thermal fixation is still a major obstacle to the automation of a printing plate manufacturing process.

It is therefore the object of the invention to provide a method for producing printing or metallic etching images of the kind set forth in the preamble of claim 1, which method may be carried out more quickly and using simpler apparatus which gives rise to a more picturesque representation which opens the way for automation, and which can be carried out at as low a temperature as possible, preferably at room temperature, without the additional step involving the fixation.

The method according to the invention, which is of the kind set forth in the preamble of claim 1, is characterized by the method of claim 1. Surprisingly, it has been found that the process according to the invention can be carried out more quickly and using simpler apparatus, that it can be carried out at low temperatures without carrying out any fixation and that according to the method according to the invention a more picturesque representation is produced.

The hydrophobing that occurs at the imaging sites is achieved by the use of a substance which, due to its chemical constitution, has hydrophobic properties and exhibits a sufficiently good adhesion to the copying layer and which is poorly soluble relative to the layer-removing agent. Therefore, as the inducer, one which uses as a toner contains the high molecular weight products of the bituminous, waxy or resinous nature specified in the characterizing part of claim 1.

Accordingly, the developing material of claim 1 also conforms to the composition of the layer removal solutions used to remove the copy layer at the non-imaging locations.

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Using the invention, it is achieved that the additional step which includes fixing, e.g. by heating or burning at an adjustable temperature range which is as constant as possible is completely e-eliminated, there is now a process for producing printing molds which can be carried out in a simple and cost-saving manner in connection with any suitable support material.

For example, if using plastic foils, after the layer removal and etching of the metal layer, transparent images are obtained at the image-free locations, at which the image teas are distinguished by a high optical density. The images that appear on the substrate are also available on the correct scale. By means of the invention, a considerable temporal and apparatus advantage is obtained, which is of decisive importance for the automation of the total method.

It is admittedly known from German Patent Specification No. 1 622,958 a method of producing a toner for a liquid, electrophotographic developer, in which the individual toner constituents enter into a chemical reaction at elevated temperature. By this known technique, advantageous production of copies according to the electrophotographic method can be obtained. This means that the toner performs a final function in the sense that the electrophotographic method is completed when the image is formed and fixed. However, the technical difficulty at this stage only begins with the method according to the invention, since it is now about getting the toner to adhere so well to the electrophotographic layer that a removal by dissolution of the portion of the layer not provided with toner is possible. This problem has been solved so far in the production of printing molds by heating to 100 to 250 ° C a fixed anchoring of resin powder, or - as is evident from Danish patent application no. 2216/67 - by using the evaporated dispersant produces an initial dissolution effect. However, the latter method, due to the presence of solvent, has not yet evaporated for a longer storage time until the solvent has evaporated. This known method is therefore also disadvantageous in the sense that one must either carry out a further heating step or that the total process must be extended in a technically disadvantageous way. In contrast, in the method of the invention, only at room temperature, the latent electrostatic image is contacted with a developer which acts hydrophobically on the imaging positions containing a more specified, high molecular weight product, while at the same time providing development and resistance to layer removal agent. .

Although German publication specification No. 2,052,201 also discloses a method for producing a lithographic plate, the toner which according to this prior art necessarily and contrary to the method according to the invention must consist of three components, namely dyeing material, asphalt and synthetic resin, are solely intended to produce a hydrophobic effect. Contrary to what is the case with the method according to the invention, a selective layer removal in connection with the non-imaging positions should not be carried out in connection with the known method. However, it is precisely for this process step that far-reaching demands are made for a self-fixing toner in terms of solvent resistance and resistance to mechanical impact, which is not at all necessary in the prior art.

According to the method according to the invention, the manufacture of flat, deep, high and silk printing forms as well as of printed circuits is possible both electrophotographically and electrographically.

The printing or metallic etching images produced by the invention by electrophotographic or electrographic means are known in principle. The use of photoconductive organics in the electrophotographic layers and their use in printing forms is known. Thus, as photoconductors, one which exhibits one or more dialkylamino groups can be used.

In particular, heterocyclic compounds such as oxdiazole derivatives disclosed in German Patent No. 1,058,836, in particular 2,5-bis- (4'-diethylamino-phenyl) -oxdiazole-1,3,4, must be mentioned. As additional suitable photoconductors, e.g. triphenylamine derivatives, higher condensed aromatic compounds such as anthracene, benzo-condensed heterocycles, pyrazoline or imidazole derivatives are disclosed. These include triazole and oxazole derivatives, as disclosed in German patents 1,060,260 and 1,120,875. Further, vinyl aromatic polymers such as polyvinyl anthracene, polyacenaphthylene, polyvinylcarbazole, and blend polymerisates of these compounds are suitable if selected for a solubility differentiation, optionally in conjunction with a resin binder. Also included in this group are polycondensates of aromatic amines and aldehydes, as known from German Patent Specification No. 1,197,325.

In addition to these listed compounds, which have predominantly β-conducting character, n-conducting compounds can also be used. These so-called electron acceptors are e.g. known from German Patent No. 1,127,218.

As resin binders, in terms of film properties and adhesion strength, natural or artificial resin is suitable. In selecting them, in addition to the film-forming and electrical properties as well as the properties associated with the adhesion strength of the support substrate, above all, the solubility properties play a special role.

For practical purposes, such resin binders are particularly suitable which are soluble in aqueous or alcoholic solvent systems, optionally during acid or alkali addition. For physiological and safety reasons, aromatic or aliphatic, easily combustible solvents are not suitable. Resin binders, preferably used, are then such high molecular weight substances which carry groups which produce alkali solubility. Such groups are e.g. acid anhydride, carboxyl, phenol, sulfonic acid, sulfonamide or sulfonimide groups. Preferably, resin binder systems are used. Mixture polymers with anhydride groups can be used with particularly good results because the conductivity of the electrophotographic layer in the dark is poor despite good alkali solubility.

Particularly suitable are blend polymers of styrene and maleic anhydride, such as e.g. those known by the name "Lutron" ^. Also phenolic resins such as, e.g. those sold under the name "Alnovol" ^ have proved suitable.

In addition, the photocopying layer in the electrophotographic printing form serving as a starting material may contain sensitizers in a known manner. These are added to the copy layer in small amounts, approx.

0.001 to approx. 1%, calculated in relation to the photoconductor ratio. Suitable sensitizers, which are essentially dyes, are e.g. disclosed in Belgian Patent No. 558,078.

For the high Ohm value layer, the resin binders described in connection with the electrophotographic layers can be used. The requirements of these layers with respect to the properties are the same as those of the photoconductor layers, whereby the photoconductor addition lapses.

As a carrier for the starting photographic electrophotographic or electrographic printing plate, all the materials known for this purpose can be used, e.g. aluminum, zinc, magnesium, chromium or copper sheets, the surfaces of which may be pretreated; but also cellulose products such as cellulose hydrate, cellulose acetate or cellulose butyrate films are suitable. Furthermore, paper or resin foils made of superficial hydrophilic and electrically conductive as well as laminated materials of paper or foil and metal can be used; also multi-metal foils are considered.

U4838 8

To produce metallic etching images, metallized plastic carriers are used in the form of foils or sheets, whereby the metal layer can be applied by evaporation, lamination or by chemical or galvanic separation.

The tones of the developers used in the process according to the origin, according to the materials listed in the characterizing part of claim 1, are hydrophobic or, because of the layer removal solution, difficult wettable substances, they differ in their solubility properties to a great extent from the copying layer, they are difficult soluble in the layer removal solutions that dissolve the copy layer at the non-imaging positions, and they additionally possess a good adhesion to the copy layer and, in addition, a good hedging effect against the image positions. It has been found that particularly suitable substances within the materials listed in the characterizing part of claim 1 are synthetic ester wax with saponification numbers between 130 and 150 and drop points between ca. 75 and 90 ° C, hard paraffin with a softening range between approx.

50 and 70 ° C, carnauba wax and high vacuum bitumen with a softening range between approx. 130 and approx. 150 ° C.

The development of the specified substances can be carried out by dry route or in the form of dispersion inducers as liquid development. Liquid induction is preferably used, employing a developer consisting of a high phase Ohm liquid phase and a solid phase dispersed therein. The liquid induction has proven to be particularly useful because of the clean, dust-free working method and the good photographic resolution.

The developer consists of a dispersing agent, of the developing substance and of aids for dispersing and controlling the charge of the developing substance. The manufacture and use of suitable aids is known from German publication no.

1047616.

Liquids which do not dissolve the solid phases at room temperature, e.g. an isoparaffin having a boiling point interval between 185 and 210 ° C. The nature of the charge of the dispersed phase depends on the properties of the dispersed substance itself and the desired dispersing agent.

As an advantageous process for preparing wax-based developer dispersions, the solution of the developer substance in the dispersant in the heat and the subsequent quenching at room temperature can be stated, leading to a finely divided wax dispersion whose suitability is excellent.

The application of the developer can be done in known manner, e.g. by immersion or roll application, which is preferred for automation, in the case of the liquid developer.

Following the development of the latent electrostatic image, the developing substance adheres image-wise to the copy layer. Then follows the application of the layer removal agent.

The solutions of the layer removal agent are applied over the layer, e.g. with a cotton ball. The plates can also be immersed directly in the liquid layer removal agent. A preferred embodiment is spraying with liquid layer removal agent. Also similarly constructed apparatus, e.g. those with liquid application rollers are suitable. This results in the desired offset pressure differentiation in hydrophilic and oleophilic regions, whereby the image sites represent the oleophilic regions.

The composition of suitable solutions of coating agent is known per se from German Patent No. 1,117,391. Alcohol blends to which alkali in the form of sodium metasilicate or ethanolamine are used as solutions of layer removal agent particularly suitable for the present invention. A 5% aqueous phosphoric acid solution is e.g. suitable as acidic layer-removing agent solution.

In addition to the treatment with the layer removal agent solution, the printing form is advantageously rinsed with water and may even further improve the hydrophobic properties of diluted phosphorus acid solution overcutting. After dyeing in bold color, the known way can then be printed in flat printing machines (offset method).

However, it is also possible to produce printing molds for high pressure and possibly also for deep printing by subsequently eliminating dissolution of the released base material.

The elimination solution can be made in etching machines which operate with one or more steps and are known for this purpose. When using multi-metal support material, etch is etched according to the usual methods of chemistry. Printing molds made according to the method of the invention give rise to the appearance of very large printing layers.

The invention will be explained in more detail in connection with the following examples.

Example 1 On a superficial rye deer, ca. 100 µm thick aluminum foil is applied to a solution of 10 g of 2-vinyl-4- (2'-chlorophenyl) -5- (4 "diethylamino-phenyl) oxazole, 10 g of a styrene-maleic anhydride blend polymer with a softening point. of 210 ° C and 20 mg of Rhodamine FB in 235. ml of glycol monomethyl ether and 65 ml of butyl acetate After evaporation of the solvent, the resulting photoconductor layer is charged negatively to 400 volts by means of a corona and illuminated in a back magnifier through a dianegative.

The illumination time amounts to using a 100 W incandescent lamp and an aperture setting of 8 thirty seconds at a 1: 5 magnification. The latent image is elicited by a liquid toner which is obtained when a fine dispersion of 1 g of a synthetic ester wax having a saponification number of 130 - 150 and a drop point of 81 to 86 ° ("Esterwachs KP") is obtained in a solution of 2 g of a pentaerythritic resin ester as a dispersing aid (e.g., "Pentalyn" ® H) in 20 ml of an isoparaffin and dilute with 1000 ml of an isoparaffin at a boiling range of 185 ° -210 ° C. 0.5 g of soya lecithin as the control agent is added to the developer.

The developed plate is converted into a printing mold, immersed for one minute in a solution of 35 g of sodium silicate in 140 ml of glycerol, 550 ml of ethylene glycol and 140 ml of ethanol and then rinsed off with a jet of water under light brushing. From the negative microfilm uptake, a positive printing form emerges.

Example 2

To proceed as described in Example 1, simply use a phenolic resin instead of the synthetic ester wax as a developing substance.

The developer is prepared by preparing a fine dispersion of 1 g of a phenol formaldehyde resin having a melting point of 75 - 83 ° C in a ball mill in a solution of 1.5 g of a pentaerythritic resin ester in 70 ml of an isoparaffin, diluted with 1000 ml of an isoparaffin with a boiling range between 185 and 210 ° C and adding 0.2 g of soya lecithin as the control agent.

Example 5

A solution of 15 g of a condensation product of N-ethylaniline and formaldehyde, 0.41 g of dibromarboxylic acid and 0.15 g of Rhodamine FB in 40 ml of toluene, 20 ml of trichlorethylene and 25 ml of methanol is applied to aluminum foil by mechanical means. After evaporation of the solvent, a photoconductor layer is obtained which is charged in the dark to 350 volts negative voltage by means of a corona. The charged film is then illuminated in a repro camera approx. 2 minutes and then developed with a liquid toner that hydrophobizes the imaging positions and covers against the influence of layer detergent. The liquid toner is obtained by producing a fine dispersion of 1 g of a hard paraffin with a softening range between 50 and 62 ° C in a solution of 2 g of a pentaerythritic ester in 20 ml of an isoparaffin and diluting with 1000 ml of an isoparaffin having a boiling point between 185 and 210 ° C. The developed plate is then bathed in 15% aqueous phosphoric acid for approx. 2 minutes. The photoconductor dissolved in the image-free places is rinsed with water.

Example 4 On an aluminum evaporated polyester film having a thickness of approx. 100 µl is applied to a solution of 10 g of 2,5-bis- (4'-diethylaminophenyl) -1,3,4-oxdiazole, 10 g of a styrene-maleic anhydride blend polymerizer having a softening point of 210 ° C and 20 mg of Rhodamine FB in 300 ml of glycol monomethyl ether. The layered film is charged with a corona to approx. 400 volts negative voltage and illuminated in contact with a film publisher with a 100 ¥ incandescent lamp at a distance of 65 cm for 3 seconds. A liquid developer is developed which dissolves or disperses 1.5 g of a high vacuum bitumen ("Bitumen D 130-140 HVB") with a softening point of 130 to 140 ° C and 6.5 g of a pentaery -thrith resin ester in 1000 ml of an isoparaffin with a boiling range between 185 ° and 210 ° C. The photoconductor layer is removed in places not covered by bitumen with a solution of sodium metasilicate, as described in Example 1. To remove the approx. light thick aluminum layers at the image-free locations are bathed in 2 n baking soda. There appears to be a good of comprehensive diapositive of the publisher.

Example 5

With an equally good result, instead of an aluminum evaporated film, a chemically nickel-plated polyester film can be used. To remove the nickel layer after image generation, a commercial nickel leaching agent is used.

Example 6

An aluminum foil provided with a photoconductor layer is used, the preparation of which is described in Example 1. The film is charged in the dark with a corona to 400 Volt negative voltage and illuminated in a repro camera for approx. 20 seconds.

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The film carrying a latent charge image is then developed in a dispersion of 1 g of collophonium in a solution of 2 g of a penta-erythrith resin ester in 1000 ml of an isoparaffin having a boiling range between 185 and 210 ° C, to which is added as a control agent. 0 * 2 g zirconyl linoleate.

The transformation of the developed plate into a printing mold is as described in Example 1.

Example 7

The aluminum foil described in Example 1, which is provided with a layer of photoconductor, is charged to 400 Volt negative voltage by means of a corona and illuminated in contact with a slide positive (film publisher). The illumination time is 3 seconds using a 100 W incandescent lamp at a distance of 65 cm. The resulting latent charge image is elicited with a liquid developer, which is made by fine dispersing 0.3 g of a white-bleached, wax-free powder shell with a melting point of 63 ° C in a solution of 0.4 g of a pentaerythritic resin ester in 1000 ml of an isoparaffin with a boiling range of 185 - 210 ° C. To the developer is added 3 ml of a 6% solution of zirconyl linoleate as the control agent.

The resulting plate is converted into a printing form in the manner described in Example 1 by eliminating resolution of the image-free positions by means of a sodium metasilicate solution.

Example 8

Proceed as described in Example 7. Instead of making «η f sounding evocation, you evoke the latent charge image with a dry toner. For this purpose, 6 g of a white-bleached, wax-free powder shellac with a melting point of 63 ° C is mixed with 100 g of iron powder with a particle size between 75 and 150 µm. This mixture is applied to the plate by means of a magnetic brush in the manner commonly used in the electrophotography. Afterwards

Claims (2)

According to the description given in Example 1, the plate is immersed in a solution containing a layer-removing agent and thereby converted into a printing form. Example 9 On a superficial roughened 100 µm thick aluminum foil, a solution of 6 g of a styrene and maleic anhydride blend polymer having a softening point of 210 ° C is applied in 74 ml of glycol monomethyl ether and 20 ml of butyl acetate. After evaporation of the solvent, the layered film is charged under a pictorially punched aluminum foil as a template by means of a corona so that the imaging positions exhibit a surface potential of 300 volts negative charge. The charge image is then developed with a liquid toner, which is prepared when dispersing 0.5 g of carauba wax in a solution of 1 g of a penetary arthritic hair ester in 10 ml of an isoparaffin and then diluting the dispersion with a solution of 0.3 g of zirconyl -2-ethylhexoate in 1000 ml of an isoparaffin with a boiling range between 185 and 210 ° C. The toner-treated film is then converted into a printing mold as described in Example 1. Patent claims: A method of producing printing molds or metallic etching guides by electrophotographic or electrographic means, thereby exposing a recording material consisting of a layer carrier and a photoconductive or high-ohmic layer therefor for charge, image illumination, or image image induction. toner image and removes the layer with a layer-removing agent at the toner image-free positions, and optionally etches the exposed carrier surface, characterized by using a developer containing toner containing high-vacuum bitumina, natural or synthetic ester waxes, hard paraffins, phenolic silica or phenol formaldehyde resin in mixture.