阅读说明：本技术 用于变压器的复合材料 (Composite material for transformer ) 是由 克里斯蒂安·黑希特 卢德格尔·拉恩 雷吉斯·勒迈特 卡斯滕·舍佩尔斯 王潮湧 英戈·罗格纳 于 2017-03-03 设计创作，主要内容包括：本发明涉及一种复合材料,尤其是用于变压器的复合材料,该复合材料包括第一和第二晶粒取向的电工钢带层和设置在其间的聚合物层,其中该聚合物层由交联的高分子量的丙烯酸酯基共聚物组成,并且层厚在3至10μm范围内。(The invention relates to a composite material, in particular for transformers, comprising a first and a second grain-oriented electrical steel tape layer and a polymer layer arranged therebetween, wherein the polymer layer consists of a crosslinked, high molecular weight acrylate-based copolymer and has a layer thickness in the range of 3 to 10 [ mu ] m.)

1. Composite material, in particular for transformers, comprising

-first and second layers of grain-oriented electrical steel strip and

-a polymer layer disposed therebetween, wherein the polymer layer consists of a crosslinked, high molecular weight acrylate-based copolymer with a layer thickness of 3 to 10 μm.

2. The composite material according to claim 1, wherein the crosslinked, high molecular weight acrylate-based copolymer consists of a copolymerization mixture and a crosslinking agent,

the copolymerization mixture is at least the following monomer units:

alkyl acrylate monomer units and/or alkyl methacrylate monomer units, both of which have an alkyl group having 1 to 12 carbon atoms,

-a glycidyl monomer unit of a glycidyl group,

-unsaturated carboxylic acid monomer units.

3. The composite material according to claim 2, wherein the average molar mass of the copolymerization mixture is 500-1500 kDa.

4. A composite material according to any one of claims 1 to 3, wherein the layer thickness of the grain-oriented electrical steel tape layer is between 50 and 1500 μm.

5. A composite material according to any one of claims 1 to 4, wherein the electrical steel strip layer has an insulating layer with a layer thickness in the range of 0.5 to 2 μm.

6. A method for the continuous production of a composite material, the method comprising the method steps of:

-providing a first layer of grain-oriented electrical steel strip,

-coating a first electrical steel tape layer with a polymer composition consisting of a high molecular weight acrylate based copolymer and a cross-linking agent,

-heating the coated grain oriented first electrical steel strip layer,

-providing and heating a second layer of grain-oriented electrical steel strip,

-laminating two grain-oriented layers of said electrical steel strip to obtain a composite material having a polymer layer consisting of a high molecular weight crosslinked acrylate-based copolymer having a layer thickness of 3 to 20 μm.

7. The method of claim 6, wherein the high molecular weight acrylate-based copolymer is formed from a copolymerization mixture comprising at least

Alkyl acrylate monomer units and/or alkyl methacrylate monomer units, both of which have an alkyl group having from 1 to 12 carbon atoms,

-glycidyl monomer units and

-unsaturated carboxylic acid monomer units.

8. The method according to claim 6 or 7, wherein the layer of grain oriented electrical steel tape is heated to a temperature of 150 to 250 ℃.

9. A composite material prepared by the method according to any one of claims 6 to 8.

10. The composite material according to claim 9, having a loss, determined according to DIN EN 60404-2, of P1.7; in the range of 0.60 to 1.0W/kg at 50Hz, and/or in the range of 1.88 to 1.96T at J800.

11. A core for a transformer comprising a plurality of thin layers of a composite material according to any one of claims 1 to 5 or 9 to 10.

12. A transformer comprising the core of claim 11.

13. A method for manufacturing a core, the method comprising the steps of:

-providing a composite material according to any one of claims 1 to 5 or 9 to 10,

-separating a plurality of sheets from the composite material, and

-gluing the sheets to form a core.

14. The method according to claim 13, wherein the attachment of the foil is performed by means of a heat-activatable adhesive.

15. Use of a composite material according to any one of claims 1 to 5 or 9 to 10 for manufacturing a core of a transformer.

Technical Field

The present application relates to a composite material, in particular for a transformer, and a method for manufacturing a composite material according to the invention. In another aspect, the present invention relates to an iron core and a transformer. Furthermore, the invention relates to a method for producing an iron core.

Background

In the case of transformers known from the prior art, the grain-oriented electrical steel strip is installed in the form of a laminate. Due to the magnetostrictive effect, it oscillates when an alternating current is applied, which results in a characteristic hum of the transformer. Since the transformer is also installed in or near the residential area, additional sound attenuation measures must be taken to reduce noise pollution. These measures are very expensive.

Other methods known from the prior art for reducing noise pollution are structural sound-absorbing composite plates, which are installed in transformers. For example, US 6,499,209B 1 discloses a transformer made of a plurality of composite sheets. Here, the individual composite sheets consist of two external magnetic layers and a viscoelastic film arranged therebetween, the film thickness being approximately 25 μm and based on crosslinked acrylic polymers.

Although such systems have the required acoustic properties and suitable adhesion values due to the correspondingly large layer thicknesses, the known systems still do not have sufficient magnetic properties for use in transformers and do not have a sufficient iron filling factor that can be achieved in the iron core when using these systems. Thus, these composite sheets have further potential for development.

Disclosure of Invention

It is an object of the present invention to provide a composite material which is improved with respect to the prior art, in particular a composite material for transformers, which has improved properties compared to monolithic electrical steel strips.

This object is achieved by a composite material having the features of claim 1.

Advantageous embodiments and variants of the invention are given by the dependent claims and the following description.

According to the invention, a composite material, in particular for transformers, comprises a first and a second layer of grain-oriented electrical steel tape and a polymer layer arranged therebetween, wherein the polymer layer consists of a crosslinked high molecular weight acrylate based copolymer and has a layer thickness in the range of 3 to 10 μm.

It has surprisingly been found that the composite material according to the invention has defined soft magnetic properties in the range of the entire electrical steel strip in comparison with the composite materials known from the prior art.

The loss of the composite material, determined according to DIN EN 60404-2, is at P1.7; preferably in the range of 0.60 to 1.0W/kg, more preferably in the range of 0.60 to 0.90W/kg, most preferably in the range of 0.60 to 0.8W/kg at 50Hz, and/or in the range of 1.88 to 1.96T field strength at J800, more preferably 1.90 to 1.96T field strength.

Furthermore, it was surprisingly found that in subsequent applications in the field of transformers, the composite material according to the invention has an iron filling factor comparable to that of the prior art, and therefore the performance is not degraded.

Preferably, the iron fill factor in a transformer using the composite material according to the present invention is 96.0% to 99.0%, more preferably 98.0% to 99.0%, still more preferably 98.3% to 99.0%.

By using the composite material according to the invention, not only can the structural noise generated in the transformer be actively reduced significantly, but in addition, efficiency can be increased by, for example, varying the thickness of the electrical steel strip used.

By having the polymer layer composed of a cross-linked high molecular weight acrylate-based copolymer, vibrations and/or oscillations may be better absorbed and converted into thermal energy. Thereby, a significant reduction of structural noise is achieved, thereby significantly reducing or even completely eliminating the use of secondary acoustic measures.

The hysteresis losses of electrical steel strip sheets are strongly dependent on the thickness of the sheet used. Generally, the smaller the thickness of an electrical steel strip, the lower the loss. By using the composite sheet according to the invention, two electrical steel strips of correspondingly better quality with a thickness of 0.20mm can be glued together compared to an electrical steel strip with a thickness of, for example, 0.40 mm. Depending on the transformer type, this may significantly improve the efficiency of the transformer, or allow a smaller transformer to be constructed with the same efficiency.

In practice, the composite material itself and the components produced therefrom are sometimes in contact with oils of very aggressive nature in the various parts, which attack the polymer layer and thus lead to delamination. Therefore, it is desirable that the polymer layer is resistant to such technical oils. Thus, it has been found that when a high molecular weight crosslinked acrylate-based copolymer is preferably composed of at least one alkyl acrylate monomer unit and/or alkyl methacrylate monomer unit (both of which have an alkyl group of 1 to 12 carbon atoms), a copolymerized mixture of glycidyl monomer units, unsaturated carboxylic acid monomer units, and a crosslinking agent, no swelling of the polymer layer or delamination of the composite is seen.

In a more preferred embodiment, the high molecular weight crosslinked acrylate-based copolymer consists of only two components, namely the copolymerization mixture and the crosslinking agent.

In a further preferred embodiment, the copolymerized mixture consists of at least one alkyl acrylate monomer unit and/or alkyl methacrylate monomer unit (wherein each monomer unit has an alkyl group having from 1 to 12 carbon atoms), a glycidyl monomer unit and an unsaturated carboxylic acid monomer unit.

Preferably, the glycidyl monomer unit is selected from: allyl glycidyl ether, glycidyl acrylate, glycidyl methacrylate and/or mixtures thereof.

Preferably, the alkyl acrylate monomer units and/or alkyl methacrylate monomer units have an alkyl group having 4 to 12 carbon atoms.

If the glass transition temperature of the polymer layer is above-15 ℃, alkyl acrylate monomer units and/or alkyl methacrylate monomer units having an alkyl group of 1 to 4 carbon atoms can be added to the mixture to be copolymerized in a preferred embodiment.

According to a preferred embodiment, the composition of the high molecular weight crosslinked acrylate-based copolymer is: at least 55 to 85 weight percent of a copolymerized mixture of alkyl acrylate monomer units and/or alkyl methacrylate monomer units, wherein each monomer unit has an alkyl group with 4-12 carbon atoms; 0 to 35 wt% alkyl acrylate monomer units and/or alkyl methacrylate monomer units, both of which have an alkyl group having 1 to 4 carbon atoms; 0.01% to 2% by weight of glycidyl monomer units; 1 to 15% by weight, more preferably 3 to 13% by weight, of unsaturated carboxylic acid monomer units; and 0.05 to 1 weight percent of a cross-linking agent.

Preferably, the average molar mass of the copolymerization mixture is 500-1500kDa, more preferably 600-1000kDa, even more preferably 700-900kDa, most preferably 800 kDa. + -. 20 kDa. The average molar mass is determined here by GPC. Polystyrene standards were used for calibration.

Preferably, the alkyl acrylate monomer units and/or alkyl methacrylate monomer units having an alkyl group with 4 to 12 carbon atoms are selected from 2-ethylhexyl acrylate, isooctyl acrylate, butyl acrylate, 2-methylbutyl acrylate, 4-methyl-2-pentyl acrylate, isodecyl methacrylate, methyl acrylate, ethyl acrylate, methyl methacrylate and/or mixtures thereof.

Preferably, the unsaturated carboxylic acid monomer units are selected from acrylic acid, methacrylic acid, fumaric acid and/or mixtures thereof. Preferred mixtures consist of acrylic acid and methacrylic acid, of acrylic acid and fumaric acid, or of methacrylic acid and fumaric acid.

According to a preferred embodiment, the copolymerization is carried out with the aid of a solvent mixture, preferably a mixture of ethyl acetate and acetone. The solvent mixture preferably has a ratio that allows reflux in the range of 68 to 78 ℃.

The solids content during the copolymerization is preferably from 40 to 60% by weight.

AIBN is preferably used as a free-radical initiator for the copolymerization.

Furthermore, the copolymerization is preferably carried out under a nitrogen atmosphere, so as to obtain a copolymer of high molecular weight, preferably with an average molar mass of > 500 kDa.

The crosslinking agent is preferably selected from aluminium acetylacetonate (AlACA), iron acetylacetonate (FeACA), titanium acetylacetonate (TiACA) or zirconium acetylacetonate (ZrACA).

According to another preferred embodiment, the layer thickness of the electrical steel strip layer is in the range of 50 to 1500 μm, more preferably 100 to 500 μm, even more preferably 150 to 350 μm, most preferably 180 to 270 μm.

To produce the composite material according to the invention, two layers of electrical steel strips having the same thickness or different thicknesses can be used.

According to another preferred embodiment, the grain-oriented electrical steel strip layer has one or preferably 2 to 5, more preferably 2 to 3 surface layers, the layer thickness of which is 0.3 to 5 μm, more preferably 1 to 2.5 μm, respectively. The surface layer exerts a tensile stress on the silicate part of the grain oriented electrical steel strip layer such that the difference between the magnetic losses of the individual sheets and the finished transformer (the so-called construction factor) is minimized.

Each layer may consist of a silicate, preferably magnesium silicate, alternatively a phosphate compound, preferably a phosphosilicate compound.

According to another preferred embodiment, the layer thickness of the polymer layer is 4 to 8 μm, more preferably 4.5 to 7.5 μm.

According to another aspect, the invention relates to a method for the continuous production of a composite material, comprising the following method steps:

-providing a first layer of grain-oriented electrical steel strip,

-coating a first layer of grain-oriented electrical steel tape with a polymer composition consisting of a high molecular weight acrylate-based copolymer and a cross-linking agent,

-heating the coated grain oriented first electrical steel strip layer,

-providing and heating a second layer of grain-oriented electrical steel strip,

-laminating two grain-oriented electrical steel tape layers to obtain a composite material having a polymer layer consisting of a high molecular weight crosslinked acrylate-based copolymer having a layer thickness of 3 to 10 μm.

The grain-oriented first electrical steel strip layer and the grain-oriented second electrical steel strip layer are preferably provided in the form of coils, whereby a continuous process for manufacturing the composite material according to the invention can be realized.

The grain-oriented first electrical steel strip layer is preferably coated by means of a coating machine. Whereby a uniform layer of the polymer composition is applied to the grain oriented first electrical steel tape layer. The application is performed in such a way that after the lamination step the composite has a polymer layer with a layer thickness in the range of 3 to 10 μm, preferably 4 to 8 μm, more preferably 4 to 8 μm, and most preferably 4.5 to 7.5 μm.

According to another preferred embodiment, the first electrical steel strip layer is pretreated between the step of providing the first electrical steel strip layer and the step of applying the polymer layer. The pre-treatment is preferably a cleaning operation. The surface of the electrical steel strip used is here freed from adhering foreign particles and oil, and is thus ready for application of the polymer composition.

In a preferred embodiment, the high molecular weight acrylate-based copolymer is formed from a copolymerized mixture of at least one alkyl acrylate monomer unit and/or alkyl methacrylate monomer unit (both of which have an alkyl group of 1 to 12 carbon atoms), a glycidyl monomer unit, and an unsaturated carboxylic acid monomer unit.

The electrical steel strip layer is preferably heated to a temperature of 150 to 250 ℃, more preferably 160 to 190 ℃, further preferably 175 to 185 ℃. The heating of the electrical steel strip layer may be accomplished by a conventional furnace or by induction. Corresponding techniques are known to the person skilled in the art.

The lamination of the two tempered electrical steel strip layers is preferably carried out by means of a folding station. Here, the first electrical steel strip layer, onto which the polymer composition is applied, is combined with the second electrical steel strip layer to obtain the composite material according to the invention.

The still hot composite is typically passed through a cooling zone where it is cooled to room temperature and then wound into a roll.

According to a particularly preferred embodiment variant, in the next process stage, the heat-activatable adhesive is applied to one side, more preferably both sides, of the composite material by means of a coil coating method.

According to another aspect, the invention relates to a composite material produced by the method according to the invention.

The composite material produced in this way preferably has soft magnetic properties in the range of the bulk grain oriented electrical steel strip plate, in contrast to the composite materials known from the prior art.

The loss of the composite material, determined according to DIN EN 60404-2, is at P1.7; preferably in the range of 0.60 to 1.0W/kg, more preferably in the range of 0.60 to 0.90W/kg, most preferably in the range of 0.60 to 0.8W/kg at 50Hz, and/or in the range of 1.88 to 1.96T field strength at J800, more preferably 1.90 to 1.96T field strength.

In another aspect, the invention relates to a core consisting of a plurality of composite material sheets according to the invention.

In another aspect, the invention relates to a transformer comprising a core according to the invention.

Another aspect of the present invention also relates to a method of producing an iron core, the method comprising the steps of:

-providing a composite material according to the invention,

-separating a plurality of sheets from the composite material, and

-connecting the sheets into a core.

The separation of the plurality of sheets from the composite material, preferably in the form of a web, can be effected, for example, by means of suitable stamping or cutting tools. The separated sheets are then stacked to form a stack and bonded to each other.

By means of the composite material, which preferably has been provided in the form of a coil, a process advantage is created in the separation compared to the manufacture of the core using a monolithic electrical steel strip plate, since only half of the separation steps are needed to provide a core with the same number of lamellae.

The joining of the sheets is preferably carried out by means of a punched cladding, wherein a mechanical bond is produced between the individual sheets. This connection is formed by protrusions punched in the respective sheets.

According to a more preferred embodiment, the individual foils are glued to one another. Bonding is preferably performed using a heat-activatable adhesive. It may be activated before, during or after stacking the sheets. The heat-activatable adhesive can thus be activated by different process steps and thus converted into a viscous state, so that separation occurs in time and/or space.

Alternatively, so-called baking lacquers (backsacks) or spot adhesives can also be used for bonding the foils.

In another aspect, the invention relates to the use of a composite material according to the invention for manufacturing a core for a transformer.

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

Examples of the invention

Different polymer compositions were prepared:

solution 1:

for this purpose, a monomer solution consisting of 207g of butyl acrylate, 61.2g of 2-ethylhexyl acrylate, 23.1g of acrylic acid and 0.1g of 2, 3-epoxypropylmethacrylate was prepared. 68.5g of this monomer solution were then taken out and introduced into a 1.5 l reactor which had been purged with nitrogen. The reactor was equipped with a stirring device, a reflux cooler and a thermistor. Subsequently, 29.7g of ethyl acetate and 18g of acetone were added to the monomer solution. The solution was heated under reflux. 0.05g of AIBN (DuPont) is then dissolved in 4.5g of ethyl acetate and added to the solution which boils under reflux. The solution was then held under vigorous reflux for 15 minutes. The remaining monomer solution was mixed with 195g of ethyl acetate, 40g of acetone and 0.24g of AIBN and added continuously as a solution to the solution boiling under reflux in the reactor over a period of 3 hours. After the addition was complete, the solution was refluxed for an additional hour. Subsequently, a solution consisting of 0.12g of AIBN, 9g of ethyl acetate and 4g of acetone was added to the reactor, and the solution was refluxed for another hour. This operation was repeated two more times. After the addition was complete, the solution was refluxed for an additional hour. Subsequently, 178g of toluene and 27g of n-heptane were added. The crude product obtained had a solids content of 36% by weight and a viscosity of 8000 pas. The viscosity was measured with a Brookfield viscometer (#4 spindle, 12U/min). The resulting copolymer consisted of 71% by weight of n-butyl acetate, 21% by weight of 2-ethylhexyl acrylate, 8% by weight of acrylic acid and 0.03% by weight of 2, 3-epoxypropyl methacrylate. The copolymer was then mixed with 0.1 wt% of aluminum acetylacetonate to obtain a polymer composition.

Solution 2:

for this purpose, a monomer solution consisting of 30g of butyl methacrylate, 150g of butyl acrylate, 27g of ethyl methacrylate, 55g of 2-ethylhexyl acrylate, 18.7g of methacrylic acid and 0.1g of 2, 3-epoxypropyl acrylate was prepared. 75.5g of the monomer solution were then taken out and charged into a 1.5 liter reactor purged with nitrogen. The reactor was equipped with a stirring device, reflux condenser and thermistor. Subsequently, 32g of ethyl acetate and 20g of acetone were added to the monomer solution. The solution was heated under reflux. 0.05g of AIBN (DuPont) is then dissolved in 4.5g of ethyl acetate and added to the solution which boils under reflux. The solution was then held under vigorous reflux for 15 minutes. The remaining monomer solution was mixed with 195g of ethyl acetate, 40g of acetone and 0.24g of AIBN and added continuously as a solution to the solution boiling under reflux in the reactor over a period of 3 hours. After the addition was complete, the solution was refluxed for an additional hour. Subsequently, a solution consisting of 0.12g of AIBN, 9g of ethyl acetate and 4g of acetone was added to the reactor, and the solution was refluxed for another hour. This operation was repeated two more times. After the addition was complete, the solution was refluxed for an additional hour. Subsequently, 183g of toluene and 27g of n-heptane were added. The crude product obtained had a solids content of 38% by weight and a viscosity of 7500 pas. The viscosity was measured with a Brookfield viscometer (#4 spindle, 12U/min). The resulting copolymer consisted of 10% by weight of butyl methacrylate, 53% by weight of butyl acrylate, 10% by weight of ethyl methacrylate, 20% by weight of 2-ethylhexyl acrylate, 6.5% by weight of methacrylate and 0.03% by weight of 2, 3-epoxypropyl acrylate. The copolymer was then mixed with 0.1 wt% of aluminum acetylacetonate to obtain a polymer composition.

Solution 3 (reference):

for reference, a viscoelastic damping material ISD 110 from 3M was used. Films having a thickness of at least 1 and 2 mils, corresponding to 25 or 50 μm, were coated according to the data sheet. The adhesive was provided with 25 and 50 μm thick paper liners and was solvent free. When heated, 5 to 30. mu.g/cm²Volatiles (hydrocarbons, organic esters, alcohols, acrylates, acetates, etc.) escape. The application is performed according to a data sheet. Air inclusions are avoided.

Solution 4 (reference):

in addition, use is made ofA company's general purpose adhesive. This is a colorless, clear and transparent gel with a gel-like thixotropic consistency. The formulation is based on a density of 0.95g/cm³The solids content of the polyvinyl ester (b) was 32% by weight. The solvent used is a mixture of a low-boiling ester and an alcohol. 50 to 70% by weight of the formulation consists of methyl acetate and 5 to 10% by weight of ethanol and acetone.

Example 1

A total of 20 transformer cores were built. In all examples according to table 1, two grain oriented electrical steel strips of the electrical steel strip type 23HP85D (nominal thickness 230 μm) or 27HP85D (nominal thickness 270 μm) and the corresponding polymer compositions were used to prepare composites.

For this purpose, the solutions 1, 2 and 4 are coated with electrical steel strips which are grain-oriented with the binder system having the stated layer thicknesses by means of a coating machine. For solution 3, a correspondingly thick layer of solid adhesive was applied without bubbles to the grain-oriented electrical steel strip using a roller. The material was then pre-dried at 110 ℃ for 1 minute to remove the solvent. For the lamination process with solutions 1 to 4 according to table 1, the corresponding electrical steel strip was then heated in a continuous furnace (furnace time about 50 seconds) to about 180 ℃. Immediately after PMT (peak metal temperature) was reached, it was laminated under pressure in a roll stand with a grain oriented electrical steel strip plate also heated to 180 ℃. For solution 3, the layer thickness achieved was about 50 μm by laminating the grain oriented electrical steel strips of the two coatings together.

From 0.8t (for 230 μm thick sheets) or 48t (for 270 μm thick sheets) of composite material, a transformer with 3 legs was constructed according to the prior art and characterized in terms of noise according to EN 60076-10.

TABLE 1

In addition, the resistance of the polymer layer was examined. For this purpose, correspondingly cut specimens (2.5X 10cm) from the composite material obtained were placed at 120 ℃ in an appropriate test fluid (Shell ATF 134FE transmission oil; Nynas NytroTaurus transformer oil (IEC60296) Ed.4-standard grade) for 164 hours. After the load time has elapsed, the test specimen is visually inspected. Neither delamination nor swelling of the polymer layer was detected here.

Drawings

Hereinafter, the present invention will be explained in more detail with reference to the accompanying drawings. In the figure:

figure 1 is a first embodiment variant of the composite material according to the invention,

figure 2 is a second embodiment variant of the composite material according to the invention,

figure 3 is a multilayer structure using a composite material according to a second embodiment variant,

fig. 4 is a process flow diagram for producing a composite material according to the present invention.

Detailed Description

Fig. 1 shows a three-layer structure of a composite material 1 according to the invention according to a first embodiment. The composite material 1 comprises a first electrical steel strip layer 2, a second electrical steel strip layer 4 and a polymer layer 3 arranged therebetween.

Fig. 2 shows a second embodiment variant of a composite material 5 according to the invention, which has a first and a second electrical steel tape layer 2,4 and a polymer layer 3 arranged therebetween. On the side opposite the polymer layer 3, the two electrical steel strip layers 2,4 each have an insulating layer 6. According to a preferred embodiment variant, this is formed by a heat-activatable adhesive.

Fig. 3 shows a multilayer structure 7 using a composite material 5 according to a second embodiment variant. The individual layers of the composite material 5 are here stacked on top of one another to form a stack. If the insulating layer 6 is formed by a heat-activatable adhesive, the multilayer structure 7 has a uniform insulating layer 6 (not shown) between the individual sheets.

Fig. 4 shows a process flow diagram for the continuous production of the composite material 1,5 according to the invention by means of a coil coating installation 10. The plant 10 has a first and a second strip unwinding station 11,12, with which a first and a second layer 2,4 of grain-oriented electrical steel strips are provided. In addition, the apparatus 10 has a joining device 13 and a first and a second strip store 14,20, which allow the coils to be replaced without having to interrupt the process. The first electrical steel strip layer 2 is first, if necessary, sent to a pretreatment stage 15 in order to remove adhering foreign particles and oil from the surface of the electrical steel strip layer 2. Subsequently, the polymer composition (not shown) is applied on one side by means of an applicator roll 16. The electrical steel strip layer 2 coated with the polymer composition is then passed through a 2-zone furnace 17, wherein the applied coating is pre-dried at 100-120 ℃. Here the solvent is removed. In the second region of the furnace 17, the electrical steel strip layer 2 is heated to PMT (170-. Furthermore, a second electrical steel strip layer 4 is supplied from the second unwinding station 12 and is first sent to a heating station 17, wherein the second electrical steel strip layer 4 is also heated to PMT. In the merging station 18, the two electrical steel strip layers 2,4 are laminated to one another at a pressure of 5kN and a temperature of 150 ℃ and 170 ℃ to give the composite material 1, 5. The still hot composite material 1,5 is then passed through a cooling station where it is cooled to room temperature and then wound into a coil at a strip winding station 21.

Description of the reference numerals

1 composite material

2 first electric steel strip layer

3 Polymer layer

4 second electric steel strip layer

5 composite material

6 insulating layer

7 multilayer structure

10 strip coating installation

11 strip unwinding station

12 strip unwinding station

13 joining device

14 strip storage

15 pretreatment stage

16 applicator roll

17 heating station

18 merge station

19 Cooling station

20 strip storage

21 strip winding station