SU295269A1 - METHOD OF GALVANICAL APPLICATION COATING ON THE SURFACE - Google Patents

Description

The invention relates to the application of paint coatings to electrically conductive products by electrodeposition.

With the known methods of electroplating on objects, when the coating with organic polymers, inorganic pigments is carried out using direct or alternating current, an electric field is created between the objects to be coated and their metal electrodes in a bath or in a liquid stream. Under the action of this field, the coating material is moved and deposited on the electrodes, and when using direct current, the coating material is deposited on only one electrode, while the alternating current causes the material to be coated on both electrodes. The prerequisite for using alternating current is that the material deposited on the electrode during one half of the alternating current phase does not dissolve when the potential changes during the other half of the alternating current phase. However, this method is applicable when using a small amount of coating material.

The methods described above are used primarily for covering large objects, as well as for covering endless ribbons that are moved through a bath. For covering small items, such methods are not applicable, since an electric current must be supplied to each covered item. Rational coverage of small offers and mass products is carried out, in particular, by a drum method.

For electroplating Hai PartsiiiiH coatings on objects by the drum method, it is necessary that the small objects to be covered that are in the drum are in constant contact with the current source. With the introduction of small objects, as with other similar methods of electroplating, into the drum, which simultaneously serves as one of the electrodes, the coating is applied

not only items, but also the walls of the drum. Metallic objects quickly lose electrical contact with the electrodump, as the film of material deposited on the drum acts as an insulator. The essence of the proposed

The method consists in the fact that one or several plies of electrodes are used, which, when introduced directly into the coloration zone in contact with the coating agent, have a rectifying effect. Such electrodes will be called

below rectifier. The rectified electrodes, the preference electrodes 10, are to be connected, as opposed to the electrodes 1U, with respect to the objects to be coated, with which one of them is in galvanic contact. It is useful to use a rectifying electrode, since it is not covered during the electrodeposition process. The coating of objects can be carried out with the help of sources of constant, alternating, pulsating, modulated pulsating and / or combined pulsating current, that is, using any kind of current sources. This method serves for electroplating at least the upper surface of electrically conductive objects with material contained in an electrically conductive liquid. Such materials include organic polymers, inorganic pigments and filler substances, as well as mixtures thereof. Liquid nocrytic agent can, like other known methods, be used in the form of a bath for submerged liquid fluids. In this case, the objects to be coated come into one-pole galvanic contact with the current source, and the current loop is closed on the means for coating. The rectifying electrodes may consist of a surface-covering porous electrically conductive material, from a semiconductor material (eg, from germanium), from a metal coated with an oxide film (for example, from aluminum coated with alumina, or from tantalum coated with tantalum oxide), or from metal coated with an organic film {for example, varnish). Below there are two different manufacturing methods for erecting electrodes. However, it should not be possible to use other electrodes with a similar effect. Example 1 In order to manufacture an aluminum electrode coated with alumina, a very thin, otherwise untreated aluminum sheet is immersed in a 9% solution of chromic acid in water and included as an anode. By the beginning of the oxidation process, the working voltage is chosen such that current density did not exceed 5 mA / cm. During the oxidation process, provided that the density of the electric current is maintained, the voltage is gradually increased, n it reaches a value of 130 e. If the voltage is no longer increased, the current density drops to 2 mA / cm. Under these conditions, the aluminum sheet is further processed for 30 minutes, then washed and dried. The treated aluminum sheet molset should be subjected to an aging process in a clean lacquer bath with variable voltage from 60 to 100 volts. Example 2 In order to obtain a varnished semiconductor electrode, a steel electrode is straightened in a bath using the straightened electrical sequence in the bath described above, after which it is washed and burned. The composition of the bath (in weight, h,): Titanium dioxide20 Soluble hardening phenolic resin75 Water15 The concentrate is diluted with water to a solids content of 10%, the pH value is set to 7.5 with an amine solution. It should be noted that sheets of bare iron, bare iron, copper or another metal, or other alloyed alloys, produce the desired effect after varnishing and firing. In this case, a pigmented or non-pigmented coating material may be used, which contains artificial resins or similar conventional coloring agents as a binder. Electrode coating is optionally carried out by galvanic deposition, immersion, or other means. It is possible to use airborne drying agents. The rectifying action of electrodes when immersed in a bath should be attributed to the manifestation of diffusion on the upper and surface electrodes. This action is exemplified by the example of a plastic coating in which an aluminum electrode coated with alumina is immersed. The no-covering tool contains binding material deposited on the anode, dissolved in water. When said rectifying electrodes have a negative notional compared with the opposite electrode, current begins to flow and the opposite electrode is coated. But if the rectifying electrode has a positive potential compared to the opposite electrode, it prevents the current from flowing further. By using the alternating go source, the rectifier of the half-wave connected to the current-free bath is achieved by using the rectifying electrode in the bath. If there is material released at the anode in the bath, then in the bath itself, due to the occurring half-wave of non-transitory current, the electrode opposite to the rectifying electrode is coated. Similarly, a group of electrodes should be used instead of the corresponding one electrode or straightening electrode. The straightening electrodes that are simultaneously in contact with the coating means can be made of the same or a different material. The intensity of the coating can be adjusted during electro saling by changing the operating voltage and at the same time or independently of this by changing the distance between the electrodes. Dyes using DC in known devices are applicable for this method. Below are some examples of coloring agents. It should be especially noted that non-pigmented baths can also be used. Example 3. A concentrate containing (in g) 35 lithopone, 3 talc, 34 water-soluble melamine resin, plasticized and drying surface, 9 butyl diglycan, 3 ethylene glycol, 9 water, diluted with water to a solids content of up to 10%. Example 4. A concentrate containing (in g) 20 titanium dioxide, 0.5 ercuzole, 0.3 carbon black, 57.3 alkyl melamine resin (70%), 14.2 water, diluted with 4 liters of water. Example 5. A concentrate containing (in g) 5 soot, 70 zinc sulfide, 10 titanium dioxide, 15 barium chromate, 150 melamine resin (60%), 100 phenolic resin (65%), diluted with 4 liters of water. Example 6. A concentrate containing, in g) 88 titanium dioxide, 7 carbon black, 15 barium chromate, 20 aluminum silicate, 4 talc, 794 melamine resin (M 490), is diluted with a mixture of water and alcohol in a 1: 1 ratio to content solids up to 20% and set with ammonia pH 7.5. Significant advantages of the proposed method over the known methods of electroplating are to reduce the cost of the device and the possibility of coating mass products using a simple method using an electric current that is not required to be supplied to each object. The subject matter of the invention 1. The method of electroplating coating on surfaces of electrically conductive objects, one pole being in galvanic contact with a current source, and the second one being closed on a coating substance contained in an electrically conductive liquid used in the form of a bath or liquid stream, differing in In order to use any type of current sources, one or a group of rectifying electrodes are used, which are mounted directly into the coating area. 2. A method according to claim 1, characterized in that the rectifying electrodes are connected as anti-aging electrodes with respect to the objects to be coated. 3. A method according to claim 1, characterized in that the rectifying electrode is in galvanic contact with the objects to be coated and the rectifying electrode is similarly used as an anti-barrier electrode. 4. Method according to paragraphs. 1-3, characterized in that the straightening electrodes are made of a semiconductor material. 5. Method according to paragraphs. 1-3, characterized in that an organic film coated with an organic film, such as lacquer, is used as the material for the electrodes. 6. Method according to paragraphs. 1-5, characterized in that during the coating process only rectifying electrodes, which are made of the same material, are applied simultaneously. 7. Method according to paragraphs. 1-5, characterized in that during the coating process, such electrodes are used which are made of different materials.