DE19754996C2 - Process for coating magnetic tapes or sheets - Google Patents

Description

The invention relates to a method for coating thin magnetic tapes or Sheets.

When processing thin magnetic tapes or sheets, it is necessary to use the Parts with an electrically insulating coating to provide contacts between prevent the sheet or strip layers. The parts made from it must subjected to heat treatment to obtain their magnetic properties become. The coating must also weld the individual sheet metal or Strip layers during annealing to adjust the magnetic properties prevent each other. Since this depends on the material and application at temperatures up to at 1200 ° C, the insulation material must be able to withstand these temperatures gene.

A coating process is e.g. B. from US-A 2,796,364. There is a Lö solution of magnesium in an alcohol from the group consisting of methyl alcohol, ethyl alcohol and Propyl alcohol described. For example, this patent provides a solution Magnesium methylate used in methyl alcohol. The sheets or strips to be insulated which are immersed in this solution or sprayed with it and then dried. What remains is a thin layer of approx. 0.1 to 1 µm made of magnesium methylate. For dic Multiple layers require a multiple pass. Leave coated tapes like this then continue processing with relatively little tool wear. By the up Removal of air humidity transforms the magnesium methylate layer into magnesi umoxid. The disadvantages of this method are the toxicity and the easy Ent flammability of methyl alcohol. It is also difficult to use thicker tapes of e.g. B. 60 to 400 µm a layer thickness in the same amount as that of low-burr belts the remaining ridges of e.g. B. 5% of the strip thickness. If necessary, very many passes through the magnesium methylate solution. Also liable the magnesium oxide layer that forms on the belt is very tight on the metal belt because  the resulting layer can adapt to the surface roughness and so too a particularly tightly adhering layer comes, what the glow to adjust the magnetic properties can lead to tension. These tensions can reduce the magnetic properties of the parts by up to 50%.

Another possibility of isolating the tapes is e.g. B. with toroidal cores, in which are particles of suitable grain size made of magnesium and / or aluminum oxide or other ceramic substances in the winding process, such as the example has been described in DE-C 38 40 509. The appropriate grain size can also be used adjust the distance between the tape layers, which is necessary to prevent gluing because of the rest to avoid burrs. Because the particles lie loosely on the belt, it comes with the subsequent annealing and cooling do not lead to tension in the material. The Disadvantages of this method, however, lie in the high tool and machine consumption wear due to the loose particles. There is also a risk that the edge areas of the toroidal cores manufactured in this way are not sufficiently insulated and so too Touching of the layers comes, which in addition to Ver can lead to welds.

A process for the production of permalloy alloys has become known from EP-B 0 480 265. Mg (OH) _{2 is used here} , with the advantage that it forms a firmly adhering film which is only converted into film-like MgO in the course of the annealing treatment to adjust the magnetic properties. A good adhesion of the layer has the disadvantage that the different coefficients of expansion of the magnetic tape and the firmly adhering layer form tensions which impair the magnetic properties of the material.

The object underlying the invention is to be seen in the ceramic sub punch suitable grain on the sheet or tape so that the Disadvantages of processing loose particles are eliminated. In addition, however, the disadvantages a very firmly adhering layer, such as when coating with magnesium methylate, be avoided, the substance after annealing without firm adhesion between the layers should lie so that no tension can occur in the material nen.  

This object is achieved by a method for coating thin, magneti shear strips or sheets, by particles of predeterminable grain size from ceramic Substances, such as magnesium and / or aluminum oxide, by means of an adhesive the tape or sheet is applied and then the tape or sheet passed through a drying area and then to the Erzeu supply of electrotechnical or electronic components, such as toroidal cores is wrapped, the adhesive then in this way from this tape or sheet that the strip or sheet is removed from a combustion process in an acid Gas containing substance is subjected, the particles then loose on the belt or sheet metal.

This object is also achieved by a method for coating thin, ma Magnetic strips or sheets by adding particles of predeterminable grain size from kerami substances such as magnesium and / or aluminum oxide by means of an adhesive be applied and then the strip or sheet by one Passed drying area and then electro to generate technical or electronic components, such as core laminated core, the strip or sheet if necessary, divided and with other strips or sheets or parts thereof, to a pa ket is layered, and the adhesive is then removed from this package it is said to contain a combustion process in an oxygen is subjected to the gas, the particles then lying loosely on the sheet.

Advantageous further developments of the subordinate methods are the associated ones See subclaims.  

The adhesive should be chosen so that it can be made after the parts have been manufactured layered tape or sheet, e.g. B the toroidal cores or the core laminated core can be removed without residue. To a large extent, adhesives consist of Carbon. The most suitable way to remove carbon is in an oxygen containing gas z. B. burn air. Other atmospheres e.g. B. hydrogen or nitrogen pose a risk of polycyclic hydrocarbon formation can then be burned without residue in the flame of the protective gas, but also depending on the length of the molecules formed and condense beforehand and dirty the oven. (Aside from their possible toxicity) This can Depending on the design of the furnace, increase to one after the other with several anneals impairment of the magnetic properties of the tape th ring cores or core laminated core or other stamped parts. The Ver However, the combustion temperature must be so low that the magnetic material its properties are not affected by the annealing in air.

The burning of the adhesive removes material between the turns or Layers removed. This process loosens the toroidal core somewhat so additionally the occurrence of stresses in the toroidal core during annealing Magnetic properties setting decreased.

In addition, the adhesive should address the processing and environmental problems at Lö avoid solvents, be water-soluble. It makes sense for the same reasons full to find a non-toxic glue so that none during processing Protective measures must be taken. As one that meets these conditions Adhesive comes z. B. a material based on cellulose ethers in question, for. B. Me ethyl celluloses, hydroxypropyl celluloses or hydroxypropyl methyl cellulose, which u. a. can also be used for medication as a shell for the tablet core. You stick when processed correctly. The layer is not rigid but deformable, so that all further processing steps such as bending, kinking, cutting and punching without Chipping of the layer is possible. It is also possible to use the layer in partial areas scrape off so that parts of the tape z. B. exposed for spot welds  can. The adhesive can also be dissolved in water after drying, which makes the coating system very easy to use.

The mixture of the adhesive dissolved in water with the particles is a suspension. In order to avoid deposits on the floor, it should be used during processing be stirred. Their viscosity can be selected by the choice of cellulose ether and the dilution vary in a wide range and so the respective application adjust type. The area of coarse particles makes sense in combination with Avoid very thin adhesive solution so as not to tend to settle too much to obtain sufficient suspensions. As application options come for thin rivers suspensions, spraying, brushing, dipping and electrophoresis.

In the case of suspensions of higher viscosity, the application is via plastic rollers with egg nem profile useful such. B. described in EP 0 480 265 B1 or DE 42 38 150 A1. The suspension can be applied on one or both sides. Degrease well The suspension can be applied without additional additives. Ver A wetting agent can be added to improve the application. After the order the suspension is to be dried. The combustion temperature of the adhesive must not be exceeded.

The band or sheet coated in this way can, for. B. to toroidal cores, core sheet packs ten and other parts are processed. After this processing, the Adhesive at temperatures between 250 and 450 ° C, preferably at temperatures between 300 ° C and 400 ° C, burned in an oxidizing atmosphere (e.g. air). There the parts can adjust the normal, the magnetic properties Be subjected to annealing process.

The process according to the invention is illustrated by the following examples.

For the isolation of magnetic tapes from a soft magnetic nickel Iron alloy was exemplified by a suspension from a solution of hydroxy propylmethylcellulose in water and magnesium oxide particles. This Sus pension was applied to both sides of the belt with profiled plastic rollers.  

Table 1

The following suspensions are listed in Table 1:

With the suspension 1 from a solution of hydroxypropylmethyl cellulose in water and magnesium oxide particles with ad _50% of 4 µm, a layer thickness of 4 µm was achieved. With the suspension 2 from a solution of hydroxypropylmethylcellulose in water and magnesium oxide particles with ad _50% of 9 microns, a layer thickness of 10 microns has been achieved. With the suspension 3 from a solution of hydroxypropylmethyl cellulose in water and magnesium oxide particles with ad _50% of 3 microns, a layer thickness of 2.5 microns has been achieved. If necessary, a wetting agent can be added to ensure good wetting even with poorly degreased tape.

From the band coated on both sides with the suspension 1, ring band cores were ge manufactures. These were annealed in air at 360 ° C to burn the adhesive. There After that, the toroidal cores were annealed to set their magnetic egg properties.

Table 2 shows the mean values of the permeabilities compared to Toroidal cores in which particles are directly in the winding process (particles directly in the Tables 2 and 3) was wrapped with the same batch of an 80% Ni 15% Fe 5% Mo alloy with 60 µm band thickness.

Table 2

Table 3 shows another example of toroidal cores from another batch the 80% Ni 15% Fe 5% Mo alloy with a band thickness of 60 µm.

Table 3

The examples in Tables 2 and 3 show that those with the invention Suspension coated cores have higher permeabilities due to the uniform allow the tape to be isolated. For both insulation options the layer thickness or the particle supply selected so that - as is generally desired - the greatest possible fill factor has been achieved, but no sticking to the Edges appeared due to the remaining burr. As you can see, with the coating of the invention achieve higher fill factors.

Table 4 shows a comparison between toroidal cores in which particles are direct were wrapped in the winding process with toroidal cores, which were made with Magnesi ummethylate coated tape were made from the same batch of an 80% Ni 15% Fe 5% Mo alloy with 80 µm band thickness.

Table 4

Table 5 also shows another example made in the same way as in Table 4 with another batch of 80% Ni 15% Fe 5% Mo alloy with 80 µm Tape thickness.  

Table 5

As you can see, the ring band cores coated with magnesium methylate have clearly Lich lower permeabilities. The cause is that very firmly on the belt surface adhesive layer.

The best values are therefore with the toroidal cores from the one with the magne silicon oxide particle adhesive suspension coated tape, the worst values achieved with the tape coated with magnesium methylate.

From tape coated with suspension 1 on both sides from a 75% Ni 18% Fe 5% Cu 2% Cr alloy with a band thickness of 350 µm, punch rings were manufactured. These became too Packages layered and then annealed in air at 360 ° C to burn the glue nen. This was followed by annealing to adjust the magnetic properties. Table 5a shows the permeabilities achieved in comparison to punch rings that from tape coated with magnesium methylate from the same batch of 75% Ni 18% Fe 5% Cu 2% Cr alloy with a band thickness of 350 µm were produced and in the same annealing were used to adjust the magnetic properties.

Table 6

As you can see, the core plate packages coated with magnesium methylate have significantly lower permeabilities.  

If the glow for setting the magnetic properties is carried out without removing the adhesive from cellulose ether - in this example at 1200 ° C under hydrogen - after a few glowings, the permeability will decrease, which cannot be completely remedied even by extending the glow times leaves. An example with toroidal tape cores from a batch of 80% Ni 15% Fe 5% Mo alloy with a tape thickness of 60 µm is shown in Table 6. The toroidal tape cores were wound from tape coated with suspension 1 and immediately afterwards subjected to annealing to adjust the magnetic properties . Annealing No. 1 in the first row of Table 7 shows the original level of the mean values of the permeabilities µ ₄ and µ _max . The annealing listed in the second line shows that the level of the permeabilities µ ₄ and µ _max after 16 further annealing can be maintained in the same furnace with ge-made toroidal cores with the help of an extension of the annealing time. After 7 further anneals in the same furnace with ring band cores produced in the same way, the permeabilities µ ₄ and µ _max then decrease despite a further increase in the annealing times. An examination of the furnace and the gas-discharging lines partially revealed tar-like deposits made of polycyclic hydrocarbons.

Table 7

Another example is shown in Table 8 with toroidal cores made with suspensions sion 1 coated tape from another batch of 80% Ni 15% Fe 5% Mo Alloy with 60 µm band thickness. The glow No. 18 in Table 8 in the same The furnace was immediately after annealing 17 in table 7. It had an annealing time of only 5 hours in contrast to annealing no. 17. One after 2 further annealing with ring band cores made from strip coated with suspension 1, annealing carried out of 10 hours (No. 21 in Table 8) with toroidal cores made from with suspensions sion 1 coated tape of the same batch as in annealing no. 18 gave one significant improvement in the mean values of the permeabilities.  

According to the invention, toroidal tape cores were then wound from tape coated with suspension 1 at temperatures of 360 ° C. in air in order to burn the adhesive of the coating. They were then subjected to annealing at 1200 ° C. for 5 hours under hydrogen to adjust the magnetic properties. Even after 17 anneals in this furnace, they were wound with toroidal cores made of strip coated with suspension 1, which were annealed at temperatures of 360 ° C. in air , a constant high level of the mean values of the permeabilities µ ₄ and µ _{max was reached} with the short glow time of 5 hours (table 8), which was higher than for the glow plug 18 and 21 in table 7. The previously observed contamination of the furnace and the Gas discharges no longer occurred.

Table 8

A surface analysis of toroidal cores, wound from with suspension 1 be layered strip after annealing at temperatures of 360 ° C in air, that the surfaces of the unwound toroidal cores free from contamination Were carbon. The investigation of from the coated with suspension 1 Band wound ring band cores after annealing at the same temperature under nitrogen or hydrogen showed that on the surfaces partially with the Visible carbon deposits were visible to the naked eye. These studies show the benefit of performing the glow to remove the glue under acidic atmosphere.

Claims (14)

1. Method for coating thin, magnetic strips or sheets by Particles of predeterminable grain size from ceramic substances, such as magnesium and / or aluminum oxide, by means of an adhesive on the tape or the Sheet metal are applied and then the tape or sheet by one Drying area passed and then for production electrotechnical or electronic components, such as toroidal cores is wrapped, the glue thereafter from this tape or Sheet metal is removed that the strip or sheet in a combustion process is subjected to an oxygen-containing gas, the particles then lie loosely on the belt or sheet. 2. Method for coating thin, magnetic strips or sheets by Particles of predeterminable grain size from ceramic substances, such as magnesium and / or aluminum oxide, are applied by means of an adhesive and the strip or sheet is then passed through a drying area leads and then to the production of electrotechnical or electronics shear components, such as core laminations, the strip or sheet metal, if necessary, divided and with other strips or sheets or parts thereof, layered into a package the adhesive is then removed from this package in such a way that the same a combustion process in an oxygen-containing Is subjected to gas, the particles then lying loosely on the sheet. 3. The method according to claim 1 or 2, characterized in that what water-soluble, non-toxic adhesive is used. 4. The method according to any one of claims 1 to 3, characterized in that a suspension of an adhesive dissolved in water with the particles inserted is set.   5. The method according to any one of claims 1 to 4, characterized in that a cellulose ether is used as the adhesive. 6. The method according to any one of claims 1 to 5, characterized in that as an adhesive methyl cellulose, hydroxypropyl cellulose or hydroxypropyl methyl celluloses are used. 7. The method according to any one of claims 1 to 6, characterized in that a wetting agent is added to the adhesive. 8. The method according to any one of claims 1 to 7, characterized in that the suspension, depending on its viscosity, by spraying, brushing, Dipping or electrophoresis is applied to the tape or sheet. 9. The method according to any one of claims 1 to 7, characterized in that the strip or the sheet metal at least on one side by means of at least one if necessary is coated with a profiled plastic roller. 10. The method according to any one of claims 1 to 9, characterized in that the strip or sheet following the coating process between counter rotating plastic, possibly with a profile rollers are passed through. 11. The method according to any one of claims 1 to 10, characterized in that layer thicknesses between 1 µm and 50 µm on the strip or sheet be put. 12. The method according to any one of claims 1 to 11, characterized in that the strip or sheet made of a soft magnetic material based of nickel and / or iron and / or cobalt.   13. The method according to any one of claims 1 to 12, characterized in that the adhesive at temperatures between 250 ° C and 400 ° C, in particular between 300 ° C and 400 ° C in an oxygen-containing atmosphere is burned. 14. The method according to any one of claims 1 to 13, characterized in that the electrical or electronic components, such as toroidal cores or Core sheet packages, for setting their intended magnetic properties create at least one glow following the combustion process be subjected to action.