WO1997047788A1

WO1997047788A1 - Process for production of a screen by electrolysis, and device for performing said process

Info

Publication number: WO1997047788A1
Application number: PCT/EP1997/003103
Authority: WO
Inventors: Martin Klemm
Original assignee: Martin Klemm
Priority date: 1996-06-14
Filing date: 1997-06-13
Publication date: 1997-12-18
Also published as: EP0907766B1; AU3258797A; ATE201725T1; DE59703680D1; DE19623724C1; EP0907766A1

Abstract

The invention relates to a process for production of a screen by electrolysis. During said process, metal from an electrolyte is deposited on electrically conductive deposit surfaces (2) of a matrix (1) in the electrolyte in such a manner that a screen with screen members (5, 6, 7) and screen openings (8, 9) is formed. The invention firstly proposes to increase the viscosity of the electrolyte to at least 50 mPas; secondly to add a protective agent (11) modified by ions to the electrolyte, said protective agent (11) being removed during deposition from each outer side (12) of the screen members (5, 6, 7) which form; thirdly to eliminate the second procedural step; and fourthly to introduce an electrically insulating protective substance (13) into the screen openings (8, 9) which form when the matrix (1) is in the electrolyte, and so that the protective substance (13) does not deposit on the outer sides (12) of the screen members (5, 6, 7) which form.

Description

Description:

Process for the electrolytic production of a screen and device for carrying out this process

The invention relates to a method for the electrolytic production of a sieve, in which metal is deposited from an electrolyte onto electrically conductive deposition surfaces of a mother die located in the electrolyte in such a way that a sieve with a sieve web and sieve openings is formed. It further relates to a device for the electrolytic production of a sieve with an electrolyte bath and a mother die which can be inserted or is used in the electrolyte strip and which has a surface which has a sieve-like pattern of electrically conductive separation surfaces.

It is known in the prior art to produce fine screens, such as those used for screen and film printing, by electroplating, that is, by means of electroplating or electroforming. A basic distinction can be made between two methods.

In one method, a mother die is used, for example, in the form of a mother plate or a mother roller, which has a regular, sieve-like pattern of electrically conductive separation surfaces, which surround electrically non-conductive regions - also called "islands". The non-conductive regions are usually produced by molding corresponding depressions in the mother die and then filling them with electrically non-conductive material flush with the surface of the separating surfaces. For the deposition process, the mother matrix is immersed in an electrolyte bath and forms the cathode there. After the electrical current has been switched on, the metal ions present in the electrolyte bath are deposited on the deposition surfaces in accordance with the pattern. Sieve webs are created in this way, while the electrically non-conductive "islands" remain essentially free of the metal ions and sieve openings are created in this way. When the desired sieve thickness has been reached, the separation process is stopped and the fully perforated sieve thus created is pulled off the mother die. A screen printing stencil is produced from such a screen in that in a subsequent process step, according to the intended printing pattern, the screen opening of parts of the screen are closed by means of template material, while those parts of the screen which are responsible for the passage of the printing ink are intended to be left open.

In the second procedure - also called galvanoplastics in the narrower sense - an electrically insulating photo layer is applied to a mother die with a smooth, metallic and thus electrically conductive surface over its entire extent. Conventional copying material can be used for this purpose, which is water-soluble, for example, but is light-curable. The photo layer is then exposed in certain areas by means of a slide, as a result of which these areas are hardened and thus fixed to the mother matrix. The remaining areas remain water-soluble so that they can be freed of the copying material in a further process step.

With the aid of this method, a fully perforated screen can be produced if it is exposed in such a way that regular, light-hardened areas result in accordance with the screen openings provided (raster copy). However, this would have been - As with the screen produced by the first method - the disadvantage that part of the screen opening would have to be closed in a subsequent process step in order to form the screen printing stencil. It is therefore preferable to combine the two processes in such a way that the areas which are said to be impermeable to the printing ink are not exposed over the entire area and in the areas which are said to be permeable to the printing ink. exposure is carried out in the areas provided for the screen openings. After the unexposed and therefore water-soluble areas have been detached, coherent separation surfaces result in the areas which are said to be impermeable to the printing ink, while in the areas which are to be provided for the passage of the printing ink, a seven-web-like pattern of Separation surfaces are formed.

Here, too, the sieve is formed in the same way as in the first method, ie the mother matrix is immersed in an electrolyte bath, and after the electrical current has been switched on, metal ions are deposited on the separating surfaces. Here, however, a sieve-like pattern of sieve webs and sieve openings only arises in the areas which are intended for the passage of the printing ink, while the metal ions separate over the entire area in the areas which are to be blocked for the printing ink. In this way, a sieve template is already formed by the galvanic deposition process, so that a subsequent closing of the sieve openings can be omitted. For reasons of language simplification, this application also speaks of sieves insofar as they are at least partially sieve-like, namely in the areas provided for the color passage. Insofar as sieve webs are mentioned below, this also means the full-area areas that arise in the second method. The problem with the galvanic production of such screens is that the screen webs that form - as well as the possibly provided full areas - not only grow perpendicular to the separation area - that is, in the direction of thickness - but also parallel over the extent of the separation areas, that is in the width direction. The reason for this is the three-dimensional structure of the resulting screen. As the sieve webs grow, the vertical flanks of the sieve webs also form separation surfaces on which metal ions settle. This is particularly disadvantageous if, on the one hand, very fine-meshed and, on the other hand, mechanically stable sieves with a large wall thickness have to be produced. However, such screens are required in particular in textile screen printing, where the screens can have a diameter of more than 300 mm and lengths of more than 3 m.

To solve this problem, the proposal has been made in US Pat. No. 4,039,397 and DE-OS 26 16 480 to divide the deposition process into several stages and, after each stage, the flanks of the parts of the sieve webs formed in each case with an electrically non-conductive insulating layer to see. Since this can practically only be done by spraying on the insulating layer, the outer sides of the sieve webs lying parallel to the separating surfaces are also provided with the insulating layer. This requires the outer sides to be freed from the insulating layer, which is done by grinding. In a modification of this method, it is proposed to gradually fill insulating material into the openings between the sieve webs.

A similar proposal is made in DE-AS 28 22 455. The deposition process is divided into a large number of individual stages, a layer of electrically non-conductive resin being applied before each deposition process. The Resin remaining on the sieve webs is removed with the aid of a non-metallic roller or plate, which has a strong affinity for the resin, in the not yet dried state. Only then can a further separation process be carried out.

A fundamental disadvantage of these proposals is that the deposition process for spraying on the insulating layer or for filling the insulating material is interrupted, i. H. the mother die is lifted out of the electrolyte bath and then provided with the insulating layer or the insulating material. Then the surfaces of the sieve webs parallel to the separating surfaces must be freed from the insulating layer or the insulating material. Only then can the deposition process be continued after the mother mold has been immersed in the electrolyte. As a result, the manufacturing process is expensive. In addition, there is the disadvantage that a certain increase in the width of the webs cannot be prevented even with these methods, since the flanks of the partial webs that are produced between two interruptions are initially unprotected. Finally, the adhesion of the individual electroplating layers is apparently not satisfactory due to the passivation of the open areas in the meantime.

The invention has for its object to design the method of the type mentioned so that it works much more economically and yet a wide growth of the screen webs is largely prevented. Another object is to provide an apparatus for performing this method.

The first part of the object is achieved according to the invention in that the viscosity of the electrolyte is increased to at least 50 mPas. This increase in viscosity has the consequence that the electrolyte in the sieve openings which form strongly depleted of metal ions because the bath circulation, which is often forced, is soothed there. This effectively reduces the width growth of the webs, since metal ion precipitation on the flanks of the sieve webs that are formed is largely avoided. The width growth can be adjusted to a desired level by adjusting the viscosity accordingly. Viscosity values up to 400 mPas are possible. Another advantage is that the deposition process does not have to be interrupted, so that the process works considerably more economically than the previously known processes.

In an embodiment of the invention it is provided that a non-ionic thickener is added to the electrolyte for increasing the viscosity. Starkeather, carboxyl-methyl-cellulose ether or polyvinyl alcohols are particularly suitable for this.

As an alternative or in combination with the above-described method, it is proposed to achieve the object that an ionically modified protective agent is added to the electrolyte in such a way that it deposits on the screen being formed, and that the protective agent is separated from the solvent during the separation process 3eweιlιgen outside of the forming webs is removed. The removal can take place continuously or intermittently, in the latter case the distances should be so small that the protective agent layer on the outside of the forming screen is reliably kept free for the metal precipitation. In this way it is ensured that the protective agent is deposited only on the flanks of the forming sieve webs, so that no metal can be deposited on them. This largely prevents the sieve webs from growing in width. This method also works very economically, because the separation process is not interrupted for external processing of the mother die must become .

The protective agent layer on the outside of the forming screen can be removed in various ways. The protective agent should preferably be stripped off, in particular scraped off. The wiping or doctoring process removes the protective agent particles continuously from the surface of the screen and at the same time transports them into the forming screen openings, where they adhere due to the electrical charge conditions. The wiping process therefore supports the precipitation of the protective agent particles on the flanks of the sieve webs.

The above-described method is not suitable without further ado for galvanoplastics in the narrower sense, in which a light-curable photo layer is applied to the smooth surface of the mother matrix. This photo layer is so sensitive even after light curing that it would be destroyed when the protective agent was stripped off, for example with the aid of a doctor blade. Nevertheless, the method is also suitable here if the stripping during the galvanization is waited until the sieve webs which have built up have reached a thickness which is greater than that of the photo layer. The photo layer is then protected from the abrasive effect of the scraper.

Studies have shown that good results are achieved even if the stripping process according to the second method is completely dispensed with. The deposition of the metal ions on the deposition surfaces is practically not disturbed by this, and the width growth of the sieve webs is surprisingly only slight. This is apparently due to the following phenomenon.

The ionically modi Protected agents on the non-conductive areas, since they are chemically related and therefore polar and non-polar interaction forces arise. So these districts are already occupied with the protective agent. When the current is switched on, the cations of the protective agent and the metal cations migrate in the direction of the deposition surfaces. There is a competitive situation between the metal ions and the protective agent cations. The metal ions apparently displace the cations of the protective agent, since the construction of the victory webs starts easily and continues unrestrictedly.

The competition situation described above is in principle also present on the flanks of the sieve webs that are being built up. Apparently, however, so many cations of the protective agent accumulate in the sieve openings that are formed that the metal ions are strongly prevented from being deposited on the flanks. This is favored by the ever-decreasing flushing action in the sieve openings, with the result that the electrolyte is depleted of metal ions. As a result, the width growth of the sieve webs remains low.

The advantages of this method lie in the fact that there is no risk of damage when using a photo layer to form the non-conductive regions. In addition, the stripping mechanism can be dispensed with. H. the usual galvanizing devices can be used.

In the development of the second and third proposal it is provided that such a protective agent is used which also increases the viscosity of the electrolyte. This supports the protective effect based on the effect described for the first proposal.

Suitable protective agents are cationic polymers on a synthetic or natural basis, e.g. B. cationically modified grained starch or cellulose, polycations based on vinyl polymers and cationic silicone polymers. Low molecular weight organic compounds which contain a cationic or at the same time anionic (amphoteric) compound and / or nonionic groups are also suitable. The materials mentioned act as thickeners in the electrolyte and cause the depletion effect described above. Since they are cationically modified, their cations migrate in the circuit to the cathode, ie to the mother matrix. The concentration of the protective agent in the electrolyte bath is preferably less than 1 g / 1.

According to the invention it is further provided that such a protective agent is used, which can be at least partially removed again after completion of the screen, so that the cross section of the screen openings through the protective agent layer is not restricted.

According to a fourth proposal, the object is achieved in that an electrically insulating protective substance is introduced into the sieve openings which form when the mother matrix is located in the electrolyte and the outer sides of the sieve webs which are formed are kept free of the protective substance. This method also works very economically in comparison with the known methods in that external processing and thus removing the mother die from the electrolyte bath is not necessary. It is still within the scope of the invention if the separation process for introducing the protective substance is interrupted. It is expedient, however, if the protective substance is introduced and the sieve webs are kept free during the separation process, that is to say simultaneously, because this saves time and avoids liability problems. The protective substance can be introduced continuously or intermittently, the latter method being used to determine the thickness To control the growth of the forming sieve webs as desired. In any case, this procedure also ensures that sieve webs are formed with flanks running practically perpendicular to the separation surfaces.

It is also possible to make the sieve openings smaller than this corresponds to the separating surfaces. For this purpose, the introduction of the protective substance into the openings formed only begins after a certain time after the separation process has been started, or the introduction of the protective substance is stopped before the separation process has ended.

In the development of this proposal, it is envisaged that the protective substance will be knife-coated. This type of introduction ensures that the protective substance is continuously kept flush with the outside of the screen being formed. At the same time, the outside of the forming screen is kept free of protective substance, so that the metal can deposit there.

In a further embodiment of the invention it is provided that the introduction of the protective substance is preceded by drying of the mother matrix. Depending on the type of protective substance, it may be necessary to provide the protective substance with areas free of the electrolyte. Drying can be carried out with compressed air, it being advantageous if the compressed air is sucked off again immediately. Alternatively or in combination, the drying can also be carried out by suction and / or stripping.

The protective substance remains in the sieve openings until the end of the separation process and is removed from the mother matrix after the sieve has been removed. Suitable materials for the protective substance are those which have no significant influence on the electrolyte bath, in particular not have a thickening effect. So z. B. waxes, pasty stearin, bituminous formulations or other pasty and resistant to the electrolyte substances.

The flank formation of the sieve openings can be influenced by the use of specific protective substances. If a highly viscous, viscoelastic paste is used, there is an expansion effect after the knife application, so that the protective substance protrudes beyond the respective sieve opening, both vertically and parallel to the separating surfaces. A corresponding effect can be achieved by a protective substance that expands when heated. It is therefore introduced into the sieve openings at a temperature which is considerably lower than the temperature of the electrolyte bath. The electrolytic bath then causes thermal expansion in all directions. It goes without saying that such behavior can also be combined with the viscoelastic material mentioned. Finally, the effect can also be achieved by using a hydrophilic protective substance. The absorbed protective substance "grows" out of the sieve opening by water absorption, with an expansion - as in the cases described above - also taking place parallel to the separating surfaces.

The second part of the task, which relates to the provision of a device for carrying out the method according to the second and fourth proposals, is achieved according to the invention in that the electrolytic bath has a stripping device with a stripping element resting on the separating surfaces of the mother die and a drive for a relative movement between the separating surface and the stripping device are assigned such that stripping can be carried out with the mother die inserted into the electrolyte bath and preferably during the separating process. This pre direction makes it possible to keep the outside of the sieve webs built up during the separation process free of a protective agent located in the electrolyte or of a protective substance of the types described above, so that the separation process does not have to be interrupted. At the same time, the protective agent or protective substance is transported through the stripping process into the sieve openings that are formed. In accordance with the second method described above, the protective agent is deposited on the flanks of the sieve webs that are formed. If a protective substance in the sense of the fourth proposal is used, the sieve openings which form are filled with the protective substance flush with the outside of the sieve.

A scraper device with a single scraper element, for example in the form of a rubberized or plastic scraper strip, is sufficient. However, several stripping elements can also be provided, either to intensify the stripping process or to keep the stripping paths short. Instead of squeegees, simpler arrangements are also possible, such as. B. a cloth or a net that wraps around the mother matrix.

In particular, the stripping device can have at least one doctor blade as a stripping element. This training is particularly suitable for carrying out the method according to the fourth proposal. For this purpose, at least one feed device should be provided, which can be combined with the stripping device for the protective substance. This makes it possible to bring the protective substance to the mother matrix in close proximity to the stripping device. For this purpose, a doctor blade is particularly suitable, which is designed as a hollow doctor blade with a doctor blade cavity open to the separation surface, which is delimited by at least two doctor blade strips and into which the feed device opens. A level sensor should be arranged in the squeegee cavity O 97/47788 PC17EP97 / 03103

13

to ensure that the protective agent or protective substance is applied evenly.

To apply a protective substance, it may be necessary to connect a drying device upstream of the stripping device so that the protective substance finds a surface freed of the electrolyte. If a hollow doctor is used, the drying device is expediently arranged in the doctor cavity. In this case, it is recommended that the doctor blade cavity be divided by an intermediate wall into a feed space into which the feed device opens and a drying room in which the drying device is arranged.

The drying device can be designed as an air blowing device, wherein an air suction device should also be provided in particular if the air blowing device is arranged in a doctor blade cavity. Alternatively, the drying device can be designed as a suction device. An embodiment is possible in which the suction device has a perforated suction pipe and a stripping layer arranged on the outside thereof, wherein the stripping layer can consist of open-cell foam.

If the mother die is cylindrical in a manner known per se for producing a circular screen, it is expedient for the drive to be designed as a rotary drive for the mother die, while the stripping device is arranged in a stationary manner. In the case of a plate-shaped, in particular flat, design of the mother die, the drive can be designed in such a way that it detaches the stripping device, for. B. reversely moved.

In principle, the mother matrix can be arranged completely immersed in the electrolyte bath. this applies especially if the procedure according to the second proposal is used. However, this arrangement is also suitable for carrying out the method according to the third proposal, especially if the stripping device has a hollow doctor blade with a feed device opening into it. If the mother matrix is cylindrical, it can also be arranged in such a way that it is only partially immersed in the electrolyte bath. The stripping device can then be arranged outside the electrolyte bath. This arrangement is particularly suitable for the method according to the fourth proposal.

The invention is illustrated in more detail in the drawing with the aid of exemplary embodiments. Show it:

1 shows a partial cross section through a

Mother matrix with a sieve deposited on it, manufactured according to the method according to the first proposal;

Figure 2 shows a partial cross section through a

Mother die with a sieve deposited on it, made according to the procedure of the second proposal;

Figure 3 shows a partial cross section through a

Mother matrix with a sieve deposited on it, produced according to the method according to the third proposal;

FIG. 4 shows a first embodiment of the device according to the invention for carrying out the method according to the third proposal,

FIG. 5 shows a cross section through a stripping device for carrying out the method according to the third proposal with feed device and drying device and

6 shows a cross section through another drying device for the stripping device according to FIG. 5.

In Figure 1, a cylindrical female die 1 is partially shown, which consists of a metal, that is, electrically conductive. It has electrically conductive separation surfaces 2 on its outside. Inserts 3, 4, which consist of electrically non-conductive material, for example ceramic, plastic or the like, are embedded in the mother matrices 1 flush with the separation surfaces 2. These inserts 3, 4 form "islands" which are distributed over the outside of the mother die 1 in such a way that they are surrounded by a sieve-like pattern of separation surfaces 2.

If this mother matrix 1 is immersed in an electrolyte bath and connected as a cathode to a power source, the metal ions contained in the electrolyte bath are deposited on the separating surfaces 2, so that a sieve with sieve webs 5 structured according to the sieve pattern of the separating surfaces 2 gradually builds up , 6, 7 builds. The thickness, i.e. H. the extent of the screen webs 5, 6, 7 perpendicular to the separating surfaces 2 can be determined by the duration of the separating process.

When using the method according to the invention according to the first proposal, a thickening agent is added to the electrolyte, which leads to a reduced exchange of the electrolyte in the sieve openings 8, 9 that form between the sieve webs 5, 6, 7. This reduced exchange causes depletion of the electrolyte, ie a reduced concentration of the metal ions in the sieve openings 8, 9, and thereby effectively reduces the pulp th growth of the sieve webs 5, 6, 7. The flanks - for example designated by 10 - have a quarter-ellipse shape with high eccentricity, ie the width growth of the sieve webs 5, 6, 7 is severely restricted. By varying the viscosity of the electrolyte bath, this effect can be adjusted according to the respective requirements.

The same mother die 1 is used in FIG. 2, which is why reference is made to the description of FIG. 1 for the description thereof and the same reference numbers are also used.

The figure shows the galvanic screen structure according to the second proposal of the invention. A cationically modified polymer is added to the electrolyte bath. Low molecular weight organic compounds which contain a cationic or at the same time anionic (amphoteric) compound and / or non-ionogenic group are also suitable. These connections accumulate in the progress of the construction of the sieve webs 5, 6, 7 as protective layers - designated 11 by way of example - on the flanks 10 of the sieve webs 5, 6, 7, so that - as FIG. 2 shows - practically vertical flanks 10 are formed. In this way, a growth in width of the sieve webs 5, 6, 7 beyond the separating surfaces 2 is prevented, i. H. the pattern of the separation surfaces 2 also corresponds to the structure of the sieve after completion.

The outer sides - designated by way of example at 12 - of the screen webs 5, 6, 7 are continuously stripped off by means of a doctor blade during the separation process. As a result, the polymer ions located in the area of the outer sides 12 are conveyed into the sieve openings and thus ensure that the flanks 10 of the sieve webs 5, 6, 7 are insulated against the precipitation of metal ions. The protective layer 11 can be removed from the mother die 1 after removal of the sieve are so that subsequently sieve openings 8, 9 with vertical flanks 10 of the sieve webs 5, 6, 7 are ready.

The same mother die 1 is also used in the illustration according to FIG. 3, which is why the same reference numbers are used for the same parts.

The structure of the sieve according to the fourth proposal of the invention can be seen from FIG. In this method, a protective substance 13 is introduced into the sieve openings 8, 9 during the separation process with the aid of special scraping devices, as can be seen in FIGS. 4 to 6, in particular by means of a doctor blade, so that the protective substance 13 is always flush with the respective one Outside of the forming webs 5, 6, 7 comes to rest. In this method, too, metal ion precipitation on the flanks 10 of the screen webs 5, 6, 7 is prevented, so that essentially vertical flanks 10 are created. The wiping of the protective substance 13 at the same time also ensures that the outer sides 12 of the screen webs 5, 6, 7 are kept free, so that the metal ions can precipitate there and the screen webs 5, 6, 7 grow in thickness. After the sieve has been removed, the protective substance 13 is removed again, for example by washing or blowing out.

The end face of the female die 1 is shown in FIG. 4, the direction of rotation being symbolized by the arrow A. A hollow doctor device 14 is arranged above the mother die 1 and, viewed in the direction of rotation, has two spaced-apart doctor blades 15, 16 made of rubber or plastic material, which extend over the length of the mother die 1 perpendicular to the plane of the drawing and are resilient rest on the mother matrix 1. The squeegee strips 15, 16 enclose a squeegee cavity 17 into which a feed tube 18 opens. The feed pipe 18 extends over the entire width of the hollow doctor device. device 14, so that the mouth of the feed tube 18 is slit-shaped. The feed pipe 18 belongs to a feed device with which the protective substance 13 already described above can be introduced into the doctor blade cavity 17. The squeegee strips 15, 16 sweep over the outer sides 12 of the respective sieve webs 5, 6, 7, so that these outer sides 12 remain free of the protective substance 13 and only the sieve openings 8, 9 are filled with them. The hollow doctor device 14 is therefore suitable for carrying out the method according to the invention according to the fourth proposal.

FIG. 5 shows a hollow doctor device 19 which is divided in two in the direction of rotation of the mother die 1 (not shown here), that is to say has two doctor cavities 20, 21. The first squeegee cavity 20 is delimited by an outer squeegee 22 and an inner squeegee 23. In operation, both doctor blades 22, 23 resiliently rest on the outside 12 of the forming webs 5, 6, 7.

A feed tube 24 of a feed device, via which the protective substance 13 is introduced into the doctor cavity 20, opens into the doctor blade cavity 20. In operation, this protective substance 13 is deposited in a wedge shape between the outer doctor strip 22 and the female die 1. A level sensor 25 projects into the doctor blade cavity 20 in the direction of the protective substance 13. The supply of the protective substance 13 can be controlled via it.

The squeegee cavity 21, which is arranged adjacent to the direction of rotation (arrow A), is delimited by the inner squeegee strip 23 and an outer squeegee strip 26. A blow slot tube 27 and a suction slot tube 28 protrude into the doctor blade cavity 21. Both also extend over the entire width of the hollow doctor device 14 (perpendicular to the plane of the drawing). The blow slot tube 27 is with his Mouth directed to the surface of the mother die 1, not shown here. It is part of a blowing device, not shown here, via which compressed air can be directed onto the mother die 1 in order to dry it. So that the blown off electrolyte is sucked off and that too high a pressure does not arise in the doctor blade cavity 23, the blown-in air is led out again via the suction slit tube 28. Because of this additional device, it is ensured that the protective substance 13 strikes a dry surface of the mother die 1.

6 shows of the hollow doctor device 19 only the left-sided doctor cavity 21 with an inner doctor bar 23 and an outer doctor bar 26. Instead of blowing and suction slit tubes 27, 28, a perforated suction tube 29 extending across the width of the hollow doctor device 19 is provided here seen, which is surrounded on the underside semicircularly by an open-pored synthetic foam 30. When the hollow doctor device 19 abuts, the foam 30 slides over the surface of the mother die 1 or the outer sides 12 of the screen webs 5, 6 and capillaryly absorbs the adhering electrolyte. The electrolyte is sucked out of the foam 30 via the suction pipe 29. In this way, the surface of the mother die 1 is dried.

Claims

Claims; Process for the electrolytic production of a screen and device for carrying out this process

1. A process for the electrolytic production of a sieve, in which metal is deposited from an electrolyte on electrically conductive deposition surfaces (2) of a mother die (1) located in the electrolyte in such a way that a sieve with sieve is at least in some areas (5, 6, 7) and sieve openings (8, 9), characterized in that the viscosity of the electrolyte is increased to at least 50 mPas.

2. The method according to claim 1, characterized in that a non-ionic thickener is added to the electrolyte.

3. Method for the electrolytic production of a sieve, in which metal is deposited from an electrolyte on electrically conductive separation surfaces (2) of a mother die (1) located in the electrolyte in such a way that a sieve with sieve webs (5, 6, 7) and sieve openings (8, 9), also according to claim 1 or 2, characterized in that such an ionically modified protective agent (11) is added to the electrolyte that it deposits on the forming sieve, and that Protective means (11) is removed from the respective outside (12) of the forming screen webs (5, 6, 7) during the deposition process.

4. The method according to claim 3, characterized in that the protective agent (11) is stripped.

5. A process for the electrolytic production of a sieve, in which metal is deposited from an electrolyte on electrically conductive separation surfaces (2) of a mother die (1) located in the electrolyte in such a way that a sieve with a sieve is at least in some areas (5, 6, 7) and sieve openings (8, 9), also according to claim 1 or 2, characterized in that such an ionically modified protective agent is added to the electrolyte that during the deposition process it moves towards the mother matrix ( 1) moves.

6. The method according to any one of claims 3 to 5, characterized in that a protective agent (11) increasing the viscosity of the electrolyte is used.

7. The method according to any one of claims 3 to 6, characterized in that an ionically modified, polymeric or low molecular weight organic compound is used as the protective agent (11).

8. The method according to any one of claims 3 to 7, characterized in that a protective agent (11) is inserted which can be at least partially removed after completion of the screen.

9. Method for the electrolytic production of a sieve, in which metal is deposited from an electrolyte onto electrically conductive separation surfaces (2) of a mother die (1) located in the electrolyte in such a way that a sieve with sieve webs (at least in some areas) 5, 6, 7) and sieve openings (8, 9), characterized in that an electrically insulating protective substance (13) is introduced into the sieve openings (8, 9) that form in the mother matrix (1) located in the electrolyte, and the outer sides (12) of the sieve webs (5, 6, 7) that are formed from the Protective substance (13) must be kept free.

10. The method according to claim 9, characterized in that the protective substance (13) in the sieve openings (8, 9) introduced during the separation process and also the outer sides (12) of the sieve webs (5, 6, 7) are kept free during the separation process.

11. The method according to claim 9 or 10, characterized in that the protective substance (13) is doctored.

12. The method according to any one of claims 9 to 11, characterized in that the introduction of the protective substance (13) precedes drying of the mother die (1).

13. The method according to claim 12, characterized in that the drying is carried out with compressed air.

14. The method according to claim 13, characterized in that the compressed air and the electrolyte are sucked off.

15. The method according to claim 14, characterized in that the drying is carried out by suction and / or stripping.

16. The method according to any one of claims 9 to 15, characterized in that a highly viscous, viscoelastic paste is used as protective substance.

17. The method according to any one of claims 9 to 16, characterized in that a protective substance is used which expands after being introduced into the sieve openings (8, 9) due to the action of heat from the electrolyte bath.

18. The method according to any one of claims 9 to 17, characterized in that a hydrophilic protective substance is used.

19. Apparatus for the electrolytic production of a sieve with an electrolytic bath and a mother die (1) which can be inserted or used in the electrolytic bath and has an outside which has a sieve-like pattern of electrically conductive separating surfaces (2), characterized in that the electrolytic bath has a Scraper device (14, 19) with at least one scraper member (15, 16, 22, 23, 26) resting on the separating surfaces (2) and a drive for a relative movement between separating surface (2) and scraper device (14, 19) are assigned in this way are that stripping can be carried out with the mother die (1) inserted in the electrolyte bath.

20. The apparatus according to claim 19, characterized in that the assignment is made so that stripping can be carried out during the deposition process.

21. The apparatus according to claim 19 or 20, characterized in that the stripping device (19) has a plurality of stripping organs (15, 16, 22, 23, 26). 22. Device according to one of claims 19 to 21, characterized in that the stripping device (14, 19) at least one doctor blade (15, 16,

22, 23, 26) as a scraper.

23. Device according to one of claims 19 to 22, characterized in that a feed device (18, 24) for the protective agent (11) or the protective substance (13) is provided.

24. Device according to one of claims 19 to 23, characterized in that the stripping device (14, 19) is combined with the feed device (18, 24).

25. The apparatus of claim 23 or 24, characterized in that the doctor blade as a hollow doctor blade (14, 19) with a to the separation surface (2) open Rakelhohl¬ space (17, 20), which by at least two Rakel¬ strips (15, 16, 22, 23) is limited and into which the feed device (18, 24) opens.

26. The apparatus according to claim 25, characterized in that a level sensor (25) is arranged in the doctor blade cavity (20).

27. The device according to one of claims 19 to 26, characterized in that the stripping device (14, 19) a drying device (27, 28, 29, 30) is connected upstream.

28. The apparatus according to claim 25 or 26 and 27, characterized in that the drying device (27, 28, 29, 30) is arranged in the doctor blade cavity (21).

29. The device according to claim 28, characterized in that the doctor blade cavity is divided by an intermediate wall into a feed space (20) in which the feed device (24) opens and into a drying space (21) in which the drying device (27, 28, 29, 30) is arranged.

30. Device according to one of claims 27 to 29, characterized in that the drying device is designed as an air blowing device (27).

31. The device according to claim 30, characterized in that the air blowing device (27) is combined with an air suction device (28).

32. Device according to one of claims 29 to 31, characterized in that the drying device is designed as a suction device (29, 30).

33. Apparatus according to claim 32, characterized in that the suction device has a perforated suction pipe (29) and a stripping layer (30) arranged on the outer side thereof.

34. Apparatus according to claim 33, characterized in that the stripping layer (30) consists of open-cell foam.

35. Device according to one of claims 19 to 34, characterized in that the mother die (1) Zy¬ cylindrical and the drive is designed as a rotary drive for the mother die (1), while the stripping device (14, 19) is arranged stationary .

36. Device according to one of claims 19 to 34, characterized in that the mother die is plate-shaped and the stripping device over the drive is movably guided.

37. Device according to one of claims 19 to 36, characterized in that the mother die is only partially immersed in the electrolyte bath and the stripping device (14, 19) is arranged outside the electrolyte bath.