Novel H-grade direct-welding electromagnetic wire coating material with high hydrolysis resistance as well as preparation method and application of novel H-grade direct-welding electromagnetic wire coating material

Abstract

The invention relates to a novel H-grade direct-weldability coating material for an electromagnetic wire with high hydrolysis resistance (high temperature and high humidity resistance), and the coating material for the electromagnetic wire is prepared from the following raw materials: polysulfone resin, polyurethane resin, novolac epoxy resin and phenolic resin. The coating material for the electromagnetic wire can fully meet the requirements of special electric appliance winding wires in various current cross-regional environments such as new energy automobiles, marine ships and aerospace.

Description

Technical Field

[0001] The present invention relates to a novel coating material for electromagnetic wires having high hydrolysis resistance (high temperature and high humidity resistance), resistance to cold and heat shock, and H-level direct welding performance, as well as a preparation method and use thereof. Background Art

[0002] As the main material for windings of electrical devices such as electrical appliances and motors, electromagnetic wire has developed over hundreds of years to form a series of products with different heat resistance levels from A to C and various characteristics. When designing industrial electrical products, according to the use occasion / environmental requirements, you can choose matching electromagnetic wires with different performance characteristics, such as mechanical properties, electrical insulation properties, chemical resistance and heat resistance, etc., and it is particularly necessary to consider the characteristics that can meet the requirements of special use environments.

[0003] At present, new electric products, mainly new energy vehicles, low-altitude economic spacecraft, drones, ships, etc., have developed rapidly. As the market layout becomes increasingly international, different usage environments have put forward new technical requirements for electrical equipment systems, such as the need to meet new assessment factors such as resistance to high / low temperature shock, large changes in temperature and humidity in different regions. These new usage requirements have added new performance indicators to the electromagnetic wires used, such as resistance to hydrolysis (humidity) and resistance to cold and hot shocks.

[0004] After conducting water resistance (such as 120℃ / 100RH / 400h) and thermal shock resistance (such as -65℃&160℃ / 1h 150 cycles) tests on various types / variety of existing electromagnetic wire products (BYD vehicle electrical standard), the results show that some of the existing electromagnetic wires (PU, PVF, PEI, PAI, PI, etc.) can pass the thermal shock resistance test, but no variety can meet the requirements of both performance tests at the same time. This reflects that the electromagnetic wire products on the market cannot simultaneously meet the hydrolysis resistance / humidity and thermal shock test required by the new standard.

[0005] Therefore, it is urgent to develop a new type of electromagnetic wire insulation material that can simultaneously meet the requirements of high hydrolysis resistance, resistance to cold and heat shock, and direct welding performance, so as to meet the high performance requirements of electromagnetic insulation materials for new electric products (such as new energy electric vehicle on-board electrical appliances (such as relays, etc.)). Summary of the invention

[0006] The object of the present invention is to provide a coating material for electromagnetic wire having excellent hydrolysis resistance (high temperature and high humidity resistance), resistance to cold and hot shock, and H-level direct welding performance, and a method for manufacturing the material. The coating material for electromagnetic wire has good basic properties (such as coating performance, surface performance, electrical insulation performance, mechanical properties), and has direct welding performance (390-420°C / 3-5 seconds), which can meet the production requirements of electrical winding wires in a hot and humid environment with rapid temperature changes.

[0007] In view of this, the present invention provides a coating material for electromagnetic wire. Among them, the raw materials for making the coating material for electromagnetic wire include: polysulfone resin, polyurethane resin, phenolic epoxy resin and phenolic resin;

[0008] Optionally, a leveling agent is further included.

[0009] Based on the solid content of the raw materials, the polysulfone resin is 110-200 parts by weight, the polyurethane resin is 90-180 parts by weight, the phenolic epoxy resin is 5.0-9.0 parts by weight, and the phenolic resin is 2.5-4.5 parts by weight;

[0010] Optionally, based on the solid content of the raw materials, the polysulfone resin is 115-194 parts by weight, the polyurethane resin is 96.9-172.5 parts by weight, the phenolic epoxy resin is 5.8-8.2 parts by weight, and the phenolic resin is 2.85-4 parts by weight;

[0011] Optionally, based on the solid content of the raw materials, the leveling agent is 0.50-2.50 parts by weight, and can be 0.63-2.31 parts by weight.

[0012] Optionally, the polysulfone resin is bisphenol A type polysulfone resin. Optionally, the weight average molecular weight is 15000-25000. Optionally, the bisphenol A type polysulfone resin is Shandong Haoran Tosu S200;

[0013] Optionally, the polyurethane resin is H-class polyurethane electromagnetic wire paint STU56 (solid content 30%), such as can be sourced from Danyang Sida Chemical Industry.

[0014] Optionally, the phenolic epoxy resin is F-type phenolic epoxy resin, and can be F-51 phenolic epoxy resin, such as can be sourced from Nantong Xingchen Synthetic Resins Co., Ltd.

[0015] Optionally, the phenolic resin is butanol etherified phenolic resin 284# (solid content 50%), and can be sourced from Kunshan Fumin Resin Materials Co., Ltd.

[0016] Optionally, the leveling agent is leveling agent TEGO FLOW370# (solid content 70%), and can be the TEGO FLOW370# leveling agent produced by Degussa in Germany.

[0017] Optionally, the raw materials for making the coating material for electromagnetic wire further include: cresol, xylene and butanol; optionally, the cresol is composed of m-cresol, p-cresol and o-cresol. Optionally, the content of m-cresol and p-cresol in the cresol accounts for ≥40%, such as can be sourced from No. 1 industrial cresol produced by Shanghai Baosteel; the xylene can be industrial mixed xylene with a purity ≥98%; the butanol can be a commercially available product with a purity ≥97%.

[0018] Optionally, the coating material for electromagnetic wire according to the present invention is made from the following raw materials: cresol, xylene, butanol, polysulfone resin, H-class polyurethane electromagnetic wire paint STU56, F-51 phenolic epoxy resin, butanol etherified phenolic resin 284#, and leveling agent TEGO FLOW370#.

[0019] Optionally, the coating material for electromagnetic wire is made from the following raw materials in parts by weight:

[0020] 189 to 305 parts by weight of cresol, 73 to 118 parts by weight of xylene, 28 to 47 parts by weight of butanol, 115 to 194 parts by weight of polysulfone resin, 323 to 575 parts by weight of H-class polyurethane electromagnetic wire paint STU56, 5.8 to 8.2 parts by weight of F-51 phenolic epoxy resin, 5.7 to 8.0 parts by weight of butanol etherified phenolic resin 284#, and 0.9 to 3.3 parts by weight of leveling agent TEGO FLOW370#; wherein, the solid content of H-class polyurethane electromagnetic wire paint STU56 is 30%, the solid content of butanol etherified phenolic resin 284# is 50%, and the solid content of leveling agent TEGO FLOW370# is 70%.

[0021] In the present invention, the solid content of each raw material refers to the mass percentage of the remaining part after drying under specified conditions to the total amount before drying. The solid components usually include film-forming substances, fillers, and additives, etc.

[0022] On the other hand, the present invention provides a preparation method for the above-mentioned coating material for electromagnetic wire, which is characterized by including the following steps:

[0023] Step a: Take cresol, xylene, and butanol according to the said parts by weight, stir and mix them evenly at room temperature, and gradually heat up to 50 ± 5°C to obtain liquid A;

[0024] Optionally, in step a, cresol, xylene, and butanol are added to a reaction kettle equipped with a condensing reflux pipe and stirred and mixed evenly at room temperature; optionally, the temperature of the stirring and mixing at room temperature is 5 - 35°C;

[0025] Step b: Take polysulfone resin according to the said parts by weight and put it into liquid A, stir and mix evenly, heat up to 90 ± 5°C during the stirring and mixing process (optionally, the time of the stirring and mixing process is 2 - 3 h), keep stirring at this temperature for 2 - 3 h, and then cool down to 50 ± 5°C to obtain liquid B;

[0026] Step c: Take polyurethane resin according to the said parts by weight and put it into liquid B, stir and mix evenly, the temperature during the stirring and mixing process is 45 - 50°C, and the time of the stirring and mixing process is 1 h - 1.5 h to obtain liquid C;

[0027] Step d: Then, take phenolic epoxy resin, phenolic resin and leveling agent respectively according to the above parts by weight, and put them into liquid C (optionally, put them into liquid C in sequence), keep the temperature at 35-45°C and stir and mix for 1.5-2 h to obtain the finished product.

[0028] Optionally, the preparation method further includes step e: Take the finished product for physical and chemical parameter detection of appearance, viscosity and solid content, filter it through a 300-mesh stainless steel filter screen and package it, and finally obtain a new type of coating material product for electromagnetic wire that meets the physical and chemical parameter standards.

[0029] On the other hand, the present invention provides the use of the above coating material for electromagnetic wire in electromagnetic wire products.

[0030] Beneficial effects:

[0031] For the coating material for electromagnetic wire of the present invention, various performance tests can fully meet the demanding hydrolysis resistance (high temperature and high humidity resistance) and thermal shock performance test requirements on the basis of meeting "Enameled Round Winding Wires GB / T 6109-2018", and can be successfully applied to the manufacture of special high-end electromagnetic wire materials with special requirements for the "water" factor, such as new energy electrical appliances, ships, and aerospace assembly electrical windings. Specific embodiments

[0032] The present invention will be further described below through examples to verify the range and correction effect of the formulation process.

[0033] In the following examples,

[0034] Cresol is industrial cresol, which is composed of m-cresol, p-cresol and o-cresol. The content ratio of m-cresol and p-cresol in the cresol is 40%, and it is sourced from No. 1 industrial cresol produced by Shanghai Baosteel; the purity of xylene is 98%, and the purity of butanol is 97%;

[0035] Polysulfone resin is Shandong Haoran Tosu S200;

[0036] H-class polyurethane enameled wire paint STU56 is sourced from Danyang Sida Chemical Industry, and the solid content is 30%;

[0037] F-51 phenolic epoxy resin is sourced from Nantong Xingchen Synthetic Resin Co., Ltd.;

[0038] Butanol etherified phenolic resin 284# is sourced from Kunshan Fumin Resin Materials Co., Ltd., and the solid content is 50%;

[0039] Leveling agent TEGO FLOW370# is TEGO FLOW370# leveling agent produced by Degussa Germany, and the solid content is 70%.

[0040] Example 1:

[0041] Step a: Take 305 parts by weight of cresol, 118 parts by weight of xylene, and 47 parts by weight of butanol, add them to a reaction kettle equipped with a condenser reflux pipe, stir and mix evenly at room temperature, and gradually heat up to 50 ± 5 °C for standby, which is called Liquid A;

[0042] Step b: Take 194 parts by weight of polysulfone resin and add it to Liquid A mixed in step a in batches, stir and mix evenly. The time for the stirring and mixing process is 2 - 3 h. During the stirring and mixing process, heat up to 90 ± 5 °C, keep stirring for 2 - 3 h, take samples for observation to ensure that the polysulfone resin is fully dissolved in Liquid A, and then cool to 50 ± 5 °C to obtain semi-finished product Liquid B;

[0043] Step c: Take 323 parts by weight of H-class polyurethane electromagnetic wire paint STU56, add it to the above semi-finished product Liquid B, stir while adding, keep the temperature at 45 - 50 °C during the stirring and mixing process, and the stirring and mixing time is 1 h. Take samples for observation to obtain semi-finished product Liquid C in a slightly transparent state;

[0044] Step d: Take 5.8 parts by weight of F-51 phenolic epoxy resin, 5.7 parts by weight of butanol etherified phenolic resin 284#, and 0.9 parts by weight of leveling agent TEGO FLOW370#, and add them to Liquid C prepared in step C in sequence, continue to stir for 2 h, and keep stirring and mixing evenly at 35 - 45 °C to obtain the finished product.

[0045] Step e: Take the finished product for physical and chemical parameter detection of appearance, viscosity and solid content. After passing the inspection, filter it through a 300-mesh stainless steel filter screen and package it to finally obtain a new type of electromagnetic wire coating material product that meets the physical and chemical parameter standards.

[0046] Example 2:

[0047] Step a: Take 260 parts by weight of cresol, 100 parts by weight of xylene, and 40 parts by weight of butanol, add them to a reaction kettle equipped with a condenser reflux pipe, stir and mix evenly at room temperature, and gradually heat up to 50 ± 5 °C for standby, which is called Liquid A;

[0048] Step b: Take 167 parts by weight of polysulfone resin and add it to Liquid A mixed in step a in batches, stir and mix evenly. The time for the stirring and mixing process is 2 - 3 h. During the stirring and mixing process, heat up to 90 ± 5 °C, keep stirring for 2 - 3 h, take samples for observation to ensure that the polysulfone resin is fully dissolved in Liquid A, and then cool to 50 ± 5 °C to obtain semi-finished product Liquid B;

[0049] Step c: Take 418 parts by weight of H-class polyurethane electromagnetic wire paint STU56, add it to the above semi-finished product Liquid B, stir while adding, keep the temperature at 45 - 50 °C during the stirring and mixing process, and the stirring and mixing time is 1 h. Take samples for observation to obtain semi-finished product Liquid C in a slightly transparent state;

[0050] Step d: Take 6.7 parts by weight of F-51 phenolic epoxy resin, 6.7 parts by weight of butanol etherified phenolic resin 284# and 1.5 parts by weight of leveling agent TEGO FLOW370#, and sequentially add them into the semi-finished product C solution prepared in step C, and continue stirring for 2 h. Keep stirring and mixing evenly at 35-45 °C to obtain the finished product.

[0051] Step e: Take the finished product for physical and chemical parameter detection of appearance, viscosity and solid content. After passing the detection, filter it through a 300-mesh stainless steel filter screen and package it to finally obtain a new type of electromagnetic wire coating material product that meets the physical and chemical parameter standards.

[0052] Example 3:

[0053] Step a: Take 234 parts by weight of cresol, 90 parts by weight of xylene and 36 parts by weight of butanol and add them to a reaction kettle equipped with a condensing reflux pipe. Stir and mix evenly at room temperature, and gradually heat up to 50±5 °C for standby, which is called solution A;

[0054] Step b: Add 144 parts by weight of polysulfone resin to solution A mixed in step a in batches and stir and mix evenly. The time for the stirring and mixing process is 2-3 h. During the stirring and mixing process, heat up to 90±5 °C, keep stirring for 2-3 h, take samples for observation to ensure that the polysulfone resin is fully dissolved in solution A, and then cool to 50±5 °C to obtain the semi-finished product B solution;

[0055] Step c: Take 480 parts by weight of H-class polyurethane electromagnetic wire paint STU56 and add it to the above semi-finished product B solution while stirring. Keep the temperature at 45-50 °C during the stirring and mixing process, and the stirring and mixing time is 1 h. Take samples for observation to obtain a slightly transparent semi-finished product C solution;

[0056] Step d: Take 7.2 parts by weight of F-51 phenolic epoxy resin, 7.2 parts by weight of butanol etherified phenolic resin 284# and 2.1 parts by weight of leveling agent TEGO FLOW370#, and sequentially add them into the semi-finished product C solution prepared in step C, and continue stirring for 2 h. Keep stirring and mixing evenly at 35-45 °C to obtain the finished product.

[0057] Step e: Take the finished product for physical and chemical parameter detection of appearance, viscosity and solid content. After passing the detection, filter it through a 300-mesh stainless steel filter screen and package it to finally obtain a new type of electromagnetic wire coating material product that meets the physical and chemical parameter standards.

[0058] Example 4:

[0059] Step a: Take 209 parts by weight of cresol, 80 parts by weight of xylene and 32 parts by weight of butanol and add them to a reaction kettle equipped with a condensing reflux pipe. Stir and mix evenly at room temperature, and gradually heat up to 50±5 °C for standby, which is called solution A;

[0060] Step b: Take 128 parts by weight of polysulfone resin and add it in batches to the liquid A mixed in step a, and stir and mix evenly. The time of the stirring and mixing process is 2 - 3 h. During the stirring and mixing process, heat up to 90 ± 5 °C, keep stirring for 2 - 3 h while maintaining the temperature, take a sample for observation to ensure that the polysulfone resin is fully dissolved in liquid A, and then cool to 50 ± 5 °C to obtain the semi-finished product liquid B;

[0061] Step c: Take 533 parts by weight of H-class polyurethane enameled wire paint STU56 and add it to the above semi-finished product liquid B. During the stirring and mixing process, keep the temperature at 45 - 50 °C, and the stirring time of the mixture is 1 h. Take a sample for observation to obtain a slightly transparent semi-finished product liquid C;

[0062] Step d: Take 7.7 parts by weight of phenolic epoxy resin, 7.7 parts by weight of butanol etherified phenolic resin 284#, and 2.7 parts by weight of leveling agent TEGO FLOW370#, and add them to the semi-finished product liquid C prepared in step C in sequence, and continue to stir for 2 h, and keep stirring and mixing evenly between 35 - 45 °C to obtain the finished product.

[0063] Step e: Take the finished product for physical and chemical parameter detection of appearance, viscosity and solid content. After passing the inspection, filter it through a 300-mesh stainless steel filter screen and package it to finally obtain a new type of enameled wire coating material product that meets the physical and chemical parameter standards.

[0064] Example 5:

[0065] Step a: Take 189 parts by weight of cresol, 73 parts by weight of xylene, and 28 parts by weight of butanol and add them to a reaction kettle with a condensation reflux pipe, stir and mix evenly at room temperature, and gradually heat up to 50 ± 5 °C for standby, which is called liquid A;

[0066] Step b: Take 115 parts by weight of polysulfone resin and add it in batches to the liquid A mixed in step a, and stir and mix evenly. The time of the stirring and mixing process is 2 - 3 h. During the stirring and mixing process, heat up to 90 ± 5 °C, keep stirring for 2 - 3 h while maintaining the temperature, take a sample for observation to ensure that the polyphenylene sulfone resin is fully dissolved in liquid A, and then cool to 50 ± 5 °C to obtain the semi-finished product liquid B;

[0067] Step c: Take 575 parts by weight of H-class polyurethane enameled wire paint STU56 and add it to the above semi-finished product liquid B while stirring. During the stirring and mixing process, keep the temperature at 45 - 50 °C, and the stirring time of the mixture is 1 h. Take a sample for observation to obtain a slightly transparent semi-finished product liquid C;

[0068] Step d: Weigh 8.2 parts by weight of F-51 phenolic epoxy resin, 8.0 parts by weight of butanol etherified phenolic resin 284#, and 3.3 parts by weight of leveling agent TEGO FLOW370# respectively, and add them to the semi-finished product liquid C prepared in step C in sequence, and continue to stir for 2 h, and keep stirring and mixing evenly at 35 - 45 °C to obtain the finished product.

[0069] Step e: Take the finished product for inspection of physical and chemical parameters such as appearance, viscosity and solid content. After passing the inspection, filter it through a 300-mesh stainless steel filter and package it to finally obtain a new type of electromagnetic wire coating material product that meets the physical and chemical parameter standards.

[0070] Perform various physical and chemical performance tests on the finished paints made from the above various embodiments. The results are shown in Tables 1 and 2 below:

[0071] Table 1: Comparison of the performance of the finished paints of each embodiment

[0072]

[0073]

[0074] Table 2: Electromagnetic wire performance of the finished paints of each embodiment

[0075]

[0076] Thermal shock test: After cycling 150 times at -65°C and 160°C for 1 hour each, there are no wrinkles, cracks or bubbles.

[0077] High temperature and high humidity test: At a temperature of 120°C and a humidity of 100RH, after 400 hours, there is no peeling or paint loss, and the withstand voltage ≥ 2000V.

[0078] The test and testing methods refer to the general provisions of "GB / T6109.1-2008 Enameled Round Winding Wires".

[0079] Table 1 shows the comparison results of the performance of the finished paints of the above various embodiments / comparative examples. From the test results in Table 1, it can be seen that the finished paints made from Embodiments 1 to 5 of the present invention meet the requirements of the design standards for all indicators.

[0080] Table 2 is the performance test report of the electromagnetic wire coated with the finished paint made from the above embodiments. It can be seen from Table 2 that the finished paints made from Embodiments 1 to 5 of the present invention have outstanding performance in electromagnetic wire performance. In particular, they have passed the harsh hydrolysis resistance test and thermal shock test, almost exceeding the hydrolysis resistance performance and high and low temperature shock test that various commercially available electromagnetic wires currently do not have, fully meeting the expected design technical goals, and can fully meet the harsh technical requirements for electrical windings in various extreme high temperature and high humidity usage environments.

Claims

1. A coating material for electromagnetic wire, characterized in that: The raw materials for making the coating material for the electromagnetic wire include: polysulfone resin, polyurethane resin, phenolic epoxy resin and phenolic resin; Optionally, a leveling agent is also included.

2. The coating material for electromagnetic wire according to claim 1, characterized in that: Based on the solid content of the raw materials, the polysulfone resin is 110-200 parts by weight, the polyurethane resin is 90-180 parts by weight, the phenolic epoxy resin is 5.0-9.0 parts by weight, and the phenolic resin is 2.5-4.5 parts by weight; Optionally, based on the solid content of the raw materials, the polysulfone resin is 115-194 parts by weight, the polyurethane resin is 96.9-172.5 parts by weight, the novolac epoxy resin is 5.8-8.2 parts by weight, and the phenolic resin is 2.85-4 parts by weight; Optionally, based on the solid content of the raw materials, the leveling agent is 0.50-2.50 parts by weight, and optionally 0.63-2.31 parts by weight.

3. The coating material for electromagnetic wire according to claim 1 or 2, characterized in that: The polysulfone resin is a bisphenol A type polysulfone resin; Optionally, the weight average molecular weight of the bisphenol A type polysulfone resin is 15000 to 25000; Optionally, the bisphenol A type polysulfone resin is Shandong Haoran Special Plastic S200; Optionally, the polyurethane resin is H-grade polyurethane electromagnetic wire paint STU56; Optionally, the phenolic epoxy resin is an F-type phenolic epoxy resin, and optionally, the phenolic epoxy resin is an F-51 phenolic epoxy resin; Optionally, the phenolic resin is butanol etherified phenolic resin 284#; Optionally, the leveling agent is leveling agent TEGO FLOW370#.

4. The coating material for electromagnetic wire according to any one of claims 1 to 3, characterized in that: The raw materials for making the coating material for the electromagnetic wire also include: cresol, xylene and butanol; Optionally, the cresol consists of m-cresol, p-cresol and o-cresol. Optionally, the content of m-cresol and p-cresol in the cresol accounts for ≥40%.

5. The coating material for electromagnetic wire according to claim 4, characterized in that: The coating material for electromagnetic wire is made of the following raw materials: cresol, xylene, butanol, polysulfone resin, H-grade polyurethane electromagnetic wire paint STU56, F-51 phenolic epoxy resin, butanol etherified phenolic resin 284# and leveling agent TEGO FLOW370#.

6. The coating material for electromagnetic wire according to claim 4, characterized in that: The coating material for electromagnetic wire is made of the following raw materials in parts by weight: The cresol is 189-305 parts by weight, the xylene is 73-118 parts by weight, the butanol is 28-47 parts by weight, the polysulfone resin is 115-194 parts by weight, the H-class polyurethane electromagnetic wire paint STU56 is 323-575 parts by weight, the F-51 phenolic epoxy resin is 5.8-8.2 parts by weight, the butanol etherified phenolic resin 284# is 5.7-8.0 parts by weight, and the leveling agent TEGO FLOW370# is 0.9-3.3 parts by weight; wherein, the solid content of the H-class polyurethane electromagnetic wire paint STU56 is 30%, the solid content of the butanol etherified phenolic resin 284# is 50%, and the solid content of the leveling agent TEGO FLOW370# is 70%.

7. The method for preparing the coating material for electromagnetic wire according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step a: taking cresol, xylene and butanol according to the weight parts, stirring and mixing them uniformly at room temperature (optionally, the temperature of the room temperature stirring and mixing is 5-35° C.), and gradually heating them to 50±5° C. to obtain liquid A; Step b: taking polysulfone resin according to the weight portion and adding it into liquid A and stirring and mixing evenly, during the stirring and mixing process (optionally, the stirring and mixing process time is 2-3 hours), the temperature is raised to 90±5° C., kept stirring at this temperature for 2-3 hours, and then cooled to 50±5° C. to obtain liquid B; Step c: taking polyurethane resin according to the weight portion, adding it into liquid B and stirring and mixing it evenly, the temperature of the stirring and mixing process is 45-50° C., and the time of the stirring and mixing process is 1h-1.5h, to obtain liquid C; Step d: taking phenolic epoxy resin, phenolic resin and leveling agent respectively according to the weight parts, putting them into liquid C (optionally, putting them into liquid C in sequence), keeping the temperature at 35-45° C. and stirring and mixing for 1.5-2 hours to obtain a finished product.

8. Use of the coating material for electromagnetic wire according to any one of claims 1 to 6 in electromagnetic wire products.

Images