DE1597846C3 - Electrophotographic process for the production of recordings on a metallic substrate - Google Patents

Description

The invention relates to an electrophotographic process for the production of records on a metallic substrate, which with at least one insulating layer is covered, in which an electrically conductive layer on the insulating Layer applied, the conductive layer covered with a layer of a photoconductive powder, the powder layer charged, exposed imagewise, the powder removed in the exposed parts of the image and the remaining powder image is optionally fixed.

In particular, the invention relates to a method of pressure marking a metal Material, for example a plate which is coated thereon with a layer of a substantially having electrically insulating paint by placing on it copies or images of photoelectrically conductive Powder materials for processing the metallic material are formed with at least an insulating layer is covered, in which an electrically conductive layer on the insulating layer applied, the conductive layer covered with a layer of a photoconductive powder, the powder layer charged, exposed imagewise, the powder in the exposed parts of the image removed and that remaining powder image is optionally fixed.

If so far metallic materials have been processed, z. B. in accordance with the by Sample or construction drawings drawn lines in the shipbuilding, aerospace and vehicle industries were cut, drawing the lines on the metal material was usually done through Measure the sizes or dimensions on the drawings and draw in the measured drawings on the metallic materials or by applying wood patterns with the actual ones Size measurements on the metallic materials and carrying out the drawing thereof or also by projecting scaled-down drawings onto the metallic ones Materials in the practical sizes and by editing the materials under Ads done with the help of a photoelectric tube.

It can be seen that these procedures require a great deal of labor and time and are technically very complicated and arduous.

Recently, a method has been proposed and applied in various technical fields, in which an electrophotographic photosensitive layer is formed on a metal plate is, after electrostatic charging of the layer, the charged layer to form an electrostatic latent image exposed, the latent image

ίο then through a toner to create a toner image is developed, which is fixed, and then the plate is cut, for example, by welding or is separated.

According to this procedure, the image is made against a high temperature or a high-temperature flame stabilized in the case of fusion cutting of metal materials. It can have a number of auxiliary representations and markings of additional images for the assembly or mounting points are determined, in addition to the lines indicated in the construction drawings be recorded on it. In addition, this method has the advantage that no error occurs the "drawing" created by hand in the process

a5 is gentle.

Moreover, according to this procedure, the photosensitive layer can be directly on the electrically conductive material can be formed, or this layer can be on a film with a relatively high electrical conductivity, e.g. B. one formed with different anti-corrosive paints Film, whereby the images can be developed.

Moreover, this image can be developed without any obstacle even if the film layer composed of various primer paints and having a thickness of 10 to 50 µm is formed on an electroconductive base.
A new method for marking or recording electrocopies has also been found in which the photoelectrically conductive powders having a satisfactorily high insulating property in the dark and a large electrification, but which extinguish their electric charge with brightness, are uniformly applied to a material having a high electric power Conductivity are scattered and are charged by a "corona discharge" or sprinkled with an electrostatic powder atomizer and a desired image is exposed or irradiated and the powder layers, in which the adhesion is electrostatically weakened by irradiation with light, by means of an external force, e.g. B. wind, blown away or removed and then the powder image is developed thereon, the image being fixed thereon, if necessary, by heating or with the aid of a solvent or binder-containing solutions.

This novel method is, compared to the method described above, that of application a coating of a photosensitive layer on the metal material is very advantageous and economical because photoconductive materials do not cover the entire surface of the metal material can be applied as a light-sensitive layer, but only for the parts where the powder image is applied and the powder is removed in areas where no image is developed can be. In addition to the above

can shorten the working stage for applying a coating on the photosensitive layer become, which is still beneficial.

The method of applying a coating of a photosensitive layer to a metal material can be applied to the surface of a metal material, even if this is up to is covered with an insulating film to some extent. According to the above Operation, however, it is necessary for the surface of the metal material that it is sufficient having electrical conductivity to form a powder image thereof, which is disadvantageous.

For example, in the shipbuilding industry, an organic or inorganic "zinc-rich" primer " used and, if these paints, a paint with a somewhat low electrical resistance represent no difficulties arise. If, however, other common paints, which form an insulating film are applied as a coating on metal materials, the development of the powder image on it is impossible, or only very blurred, imprecise images can be obtained will.

The object of the invention is therefore to provide an electrophotographic process for production of recordings on a metallic substrate, in which the above-described, opposing points are ideally balanced.

The electrophotographic method of manufacture of recordings on a metallic substrate according to the invention with at least an insulating layer is covered, in which an electrically conductive layer on the insulating Layer applied, the conductive layer covered with a layer of a photoconductive powder, the powder layer charged, exposed imagewise, the powder removed in the exposed parts of the image and that remaining powder image is optionally fixed, which is characterized in that as electrical conductive layer a layer with a quaternary ammonium salt, alkylarylsulfonate, aliphatic Sulphonate, sodium stearylbenzotriazolesulphonic acid or with a polyoxyethylene alkylaryl ether is applied.

In the method according to the invention, for the production of electrical print records on metal substrates a solution beforehand that contains an antistatic agent or such as a component. contains components in a mixture, applied as a coating to the film-like surface of the metal material, this a photoelectrically conductive powder is sprinkled on, whereupon the following Stages are executed.

Steel plates are commonly used in the metal materials processing or handling industries Treated by means of sandblasting or grain blasting to remove mill scale from the surface of the Remove the steel plate and immediately apply anti-corrosive coatings, in order to obtain protection against corrosion.

The method according to the invention for the production of electrical pressure recordings is therefore special advantageous in the treatment or processing of metal materials referred to in the above were treated in the manner indicated.

For example, after performing the sandblasting treatment of steel plates, the method the electroprint recording treatment on these steel plates in accordance with Methods of powder image formation are practically carried out; However, the coating of anti-corrosive leads Painting in the subsequent stage to a poorer effectiveness, and additional "Instructions" are deleted.

In particular, when coated with an anti-corrosive paint, the previous staining occurs the material with the residual powder, which is used to form powder images, in appearance, and this is not wanted. In the shipbuilding industry, marking can be carried out directly on steel plates are carried out, however, the electrical pressure recording or marking is usually carried out on a Executed film surface, which has an insulating behavior in various degrees. That's how it is The method according to the invention is very effective in the treatment of metal materials similar to those above Have the described insulating surface of the coating film. According to the procedure according to According to the invention, an image can be developed without any hindrance to practical operation is brought about, and it can be practically carried out, even if the film-like Layers as a result of different primer coats with a thickness of 100 μ or less the conductive material are formed.

The method according to the invention is carried out in such a way that a substance with a antistatic behavior (or a mixture containing this substance) in an organic solvent or dissolved or dispersed in water or in a mixture thereof and the resulting Spray the solution on the surface of the metal material that is isolated by the primer coats or as a coating to make them adhere to that surface.

The substance used here is required to have an antistatic behavior in adequate Extent has an effect to impart electrical conductivity to the surface and also has a lower adhesion to the photoelectrically "conductive powder materials. (Hereinafter, this substance will be referred to as a treatment agent). Examples of such substances are a quaternary ammonium salt, e.g. B. trimethyloctadecylammonium chloride or trimethyldodecylammonium chloride, an alkyl aryl sulfonate, e.g. B. butylnaphthalene sodium sulfonate or alkylbenzene sodium sulfonate, an aliphatic sulfonate, e.g. B. dioctyl sodium sulfonate, stearyl benzotriazole sodium sulfonate or the like

The image will be on the surface after the Process according to the invention has been treated, whereupon the treatment agent if necessary can be washed off.

However, it has been found that when the coating thickness by the treating agent is below 0.2 μ is, this serves to promote the image and also has no adverse effects on the paint, which is applied later delivers.

In addition, when these surface treatment agents can be coated with the paints the metal plate, imparting electrical conductivity to the film, the image

developed by the electrophotographic process, with photoconductive powders on the Surface to apply. In this case, a multiple or more of the Materials for surface treatment are added to the paint compositions in excess of the necessary amount.

Moreover, in the case of mixing the electroconductive substance with the paint, a Film with a thickness of 5 to 100 μ is formed on the metal plate, whereupon the surface is caused by »corona discharge« is charged, and a poorer picture is developed, even if the electric Potential on the surface is low, while in contrast after the treatment process according to the invention the image from the photoconductive powder by the electrophotographic Process is rapidly developed on the surface, essentially leaving a practical image is obtained even if the electric potential on the surface is above several times of the potential given above.

In addition, it is not necessary in the treatment method according to the invention, short-circuit contacts between the treated surface and the metal conductor.

According to these working methods for surface treatment the film coating on the conductor surface has a high insulating property and, if one The thickness of 100μ is exceeded, the image development cannot be carried out satisfactorily will.

The invention is explained in more detail below with the aid of examples.

example 1

A zinc chromate primer was applied as a coating to a steel plate in a thickness of 20 μm, whereupon the plate was dried.

A solution of 0.1 part (based on weight, the parts given below are always parts by weight) an anionic surfactant, of the formula below:

(NaO ₃ S) _n -

45

CH,

90 parts of propanol and 10 parts of water were sprayed on the steel plate by means of an atomizing machine so that the spraying was uniform at a rate of 60 g / m ² , and the plate was dried.

Then, a photoconductive powder was sprinkled in an amount of 80 g / m ² on the treated surface of the steel plate by means of a sieve. These powders were charged by means of a corona discharge machine for -10 kV.

The powders were also irradiated to obtain an image, whereupon an air brush with a Capacity of 10 m / sec wind speed was applied to blow off the powder. There were the powders on those parts that have been exposed to the irradiation are removed, but the Powder remained on the unirradiated parts. The powders on the unirradiated parts were electrostatically connected to the surface and remained on the surface layers of the steel plate, that had been fully treated. Overall, a strong image was obtained. It was, however not possible to develop an image on an untreated steel plate.

The photo-conductive powder used in this example had the following composition:

Parts

photoelectrically conductive zinc oxide 75
Silicone resin paint for electrical

insulating coatings 40

Cyclohexane 13.5

Eosin 0.037

The above components were ground in a ball mill for 20 hours. Furthermore, polymethyl methacrylate with an average grain diameter of 70 μ was obtained by suspension polymerization.
150 parts of the kneaded solution and 15 parts of cyclohexane were added and mixed with 100 parts of polymethyl methacrylate, and the resulting mixture was atomized by a spray dryer and dried, and further dried for 4 hours in a vacuum dryer. The dried material was then separated by a partial compactor to remove fine particles having a diameter of 10 µm or less, and the desired powder was obtained.

Example 2

0.5 part of a nonionic surfactant, namely polyoxyethylene alkyl ether, was dissolved in 100 parts of ethyl alcohol. This mixture was sprayed in an amount of 50 g / m ² onto the surface of a steel plate, which was coated with an Oxydrot primer to a thickness of 20 μm, whereupon the surface was dried.

The image development was then carried out according to the procedure given in Example 1 on the in the above treated material was carried out, whereby a vivid image was obtained.

On the other hand, a similar treatment was applied to a steel plate, that of the Oxydrot primer was coated in a thickness of 20 μm. Included however, no image was obtained in which the powder was intensely adhered to the coating layer.

B e i s ρ i e 1 3

Aluminum plates were coated with the paint oxide red primer (sample 1) to a thickness of 15 μm. Then, a solution of 0.5 part of a cationic surfactant, namely trimethyloctadecylammonium chloride, and 100 parts of water was sprayed on the aluminum plate ^{in an amount of 40 g / m 2 (Sample 2).}

A solution of 100 parts of the paint of an Oxydrot primer and 2 parts of the cationic Trimethyloctadecylammonium chloride surfactant was applied to an aluminum plate up to sprayed on a dry thickness of 15 μm (sample 3).

These three samples were discharged by a corona discharge device of -10 kV at a rate of magnitude guided by 10 cm / sec, and in

in this case the film surfaces became immediate
kept under the machine. The electrical potentials on the film surfaces were measured at the first stage and resulted in 250 V for sample 1,
V for sample 2 and 70 V for sample 3. 5

Then a discharge was made for 30 seconds
executed these electrified conditions. Thereafter, Samples 1, 2 and 3 showed 180, 70, respectively
or 25 V.

Medium grain photoconductive powder

diameter of 60 μΐη were to an extent of about 85 g per m - over the three types of primed or coated panels using a spreader sprinkled for electrostatic powder. Then it was developing images through exposure executed. As a result, it was found that sample 1 was impossible to form an image Sample 2 showed a very favorable image and sample 3 a heavily fogged, somewhat deteriorated one Image delivered.

Claims (1)

Claim: Electrophotographic process for making records on a metal Layer support which is covered with at least one insulating layer, one of which is electrical conductive layer applied to the insulating layer, the conductive layer with a layer covered from a photoconductive powder, the powder layer charged, imagewise exposed, the Powder removed in the exposed parts of the image and the powder image that remains, if necessary is fixed, characterized in that the electrically conductive layer is a layer with a quaternary ammonium salt, alkylarylsulfonate, aliphatic sulfonate, sodium stearylbenzotriazole sulfonic acid or with a polyoxyethylene alkylaryl ether is applied.