Softening-resistant low-temperature soldering tin H-level enameled wire and production process thereof

Abstract

The invention relates to a softening-resistant low-temperature soldering tin H-grade enameled wire and a production process thereof.The enameled wire is composed of a wire and a coating, the coating comprises a bottom coating and a surface coating, and the bottom coating is obtained by coating H-grade heat-resistant polyurethane paint with the solid content of 25%-30% and the viscosity of DIN 4 # 20-30 s; the surface coating is obtained by coating self-lubricating polyurethane paint with the solid content of 23%-28% and the viscosity DIN4 # of 15-25 s. The production process comprises the steps of raw material selection, wire drawing, annealing, cooling, cleaning, painting, curing, cooling and take-up.

Description

Technical Field

[0001] The invention relates to the technical field of enameled wire processing, and in particular to a softening-resistant low-temperature solder H-class enameled wire and a production process thereof. Background Art

[0002] With the development of new energy electric vehicles, the new energy vehicle market has expanded from the early urban market to the township market. Going to the countryside has become an important measure to revitalize the performance of the automobile market and promote the development of the automobile industry. At the same time, the National Energy Administration actively promotes the layout of charging facilities in rural areas, and the scale of the new energy charging infrastructure system continues to expand. As an important material for charging pile transformers, enameled stranded wire single wire has huge market potential.

[0003] At present, the most commonly used stranded wires on the market are F-class (155 heat resistance class) and ordinary H-class (180 heat resistance class) wires. The performance of the enameled wire is directly related to the overall performance and service life of the charging pile. Due to defects in the production process, F-class products have low heat resistance and cannot meet the needs of fast charging and continuous use. If used continuously, overload and burnout may occur. Although ordinary H-class polyurethane enameled wire can withstand high temperature environments up to 180°C and has a higher softening temperature than F-class, it still cannot meet the requirements of fast charging and continuous use: During the soldering process, a single strand of solder requires a high temperature of 370°C for 2s to penetrate; when soldering multiple strands, it still cannot penetrate at 430°C and 5s. Therefore, the welding process may damage the insulation layer of the enameled wire and affect its electrical performance.

[0004] Therefore, how to provide a softening-resistant, low-temperature soldering enameled wire and its production process is a technical problem that needs to be urgently solved in the application field of new energy vehicle charging piles.

[0005] Traditional polyurethane enameled wires are usually composed of a three-layer structure consisting of a metal conductor + a polyurethane insulation layer (some enameled wires also include nylon paint as a topcoat to increase the lubricity of the enameled wire) + a lubricating oil layer. For example, the patent with the announcement number CN109767876B prepared a three-layer structure of direct-welded 180-grade polyurethane enameled wire, but the soldering temperature of the enameled wire is still not less than 370°C. Xu Licun et al. (patent announcement number CN112133494B) improved the layer structure on the basis of the existing polyurethane enameled wire and prepared a polyurethane enameled wire that does not require a special lubricating layer. However, the patent only states that the prepared polyurethane enameled wire has low organic gas volatility, and does not involve the soldering temperature and whether it is easy to solder.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] The first purpose of the present invention is to provide a H-class enameled wire resistant to softening and low-temperature soldering in view of one of the deficiencies of the current technology, so that the polyurethane enameled wire is resistant to high-temperature softening and can realize low-temperature soldering.

[0008] The second object of the present invention is to provide a production process for H-class enameled wire resistant to softening and low-temperature soldering.

[0009] To achieve the above-mentioned purpose, the technical solution of the present invention is: a softening low-temperature solder resistant H-class enameled wire, which is composed of a conductor and a coating, wherein the coating includes a primer coated on the surface of the conductor and a top coating coated on the primer, wherein the primer is obtained by coating at least 7 coats of an H-class heat-resistant polyurethane paint with a solid content of 25% to 30% and a viscosity of DIN4# 20s to 30s; and the top coating is obtained by coating a self-lubricating polyurethane paint with a solid content of 23% to 28% and a viscosity of DIN4# 15s to 25s.

[0010] When manufacturing traditional enameled wires, a layer of lubricant must be applied to the surface of the enameled wires to make the enameled wires tightly arranged when they are wound up, which is conducive to the winding companies to release the wires smoothly and prevent them from breaking easily. However, if too much lubricant is applied, the lubricant will be thrown out during the high-speed release process during winding, which will directly pollute the air in the production environment of the winding company. At the same time, since the lubricant is volatile, it is easy to evaporate in the working environment of electronic components. If too much lubricant is applied, it is easy to accelerate oxidation and aging corrosion of the paint film under long-term influence, making the enameled wires more prone to aging, failure, and loss of insulation effect. In addition, the non-volatile aromatic substances in the enameled wire paint film will gradually escape when the electronic components are working. When the enameled wire is used as the winding wire of a sealed electronic component or an electronic component with high environmental protection requirements, these volatile gases will be adsorbed on the contact surface of the electronic component in a closed environment, and gradually corrode these metal parts under the action of the electric arc, reducing the service life of the electronic component in advance, and eventually causing the entire electronic control system to lose control or paralyze, or even damage and scrap the entire machine, so the unvolatile aromatic substances in the paint film and the lubricant content on the surface of the enameled wire should be reduced as much as possible. This application uses a H-class heat-resistant polyurethane paint with a solid content of 25%~30% and a viscosity of DIN4#20s~30s as the base coat; a self-lubricating polyurethane paint with a solid content of 23%~28% and a viscosity of DIN4#15s~25s as the top coat, which does not require a lubricating oil layer, greatly reducing the impact of volatiles, and the resulting enameled wire is resistant to high temperature softening, meeting the use requirements of H-class enameled wire. The paint film composed of this polyurethane paint is easily decomposed into low molecular substances and volatilized when the solder is heated, optimizing the application process, promoting the formation of a good interface with the solder, and improving the welding strength.

[0011] Furthermore, the total thickness of the paint film of the primer and the topcoat is 0.018 mm to 0.028 mm, and the thickness ratio of the primer film thickness to the topcoat film thickness is 11 to 12. The appropriate paint film thickness ensures insulation, high softening resistance, electrical reliability and stability, and also saves the amount of paint and reduces the impact of volatiles during use.

[0012] Furthermore, the thickness of the primer film is the thickness of 7 to 8 coats of H-grade heat-resistant polyurethane paint, and the thickness of the topcoat film is the thickness of 1 to 2 coats of self-lubricating polyurethane paint. The appropriate thickness of the primer ensures the insulation requirements, and the self-lubricating polyurethane paint is coated on the surface, which plays an insulating role on the one hand and a lubricating role on the other hand, so that the enameled wire is tightly arranged when it is taken up, which is beneficial for the winding enterprise to release the wire smoothly during use and not easy to break the wire.

[0013] Furthermore, the H-grade heat-resistant polyurethane paint is a 215 / 28S or 56 / 28LS polyurethane paint, and the self-lubricating polyurethane paint is a STU56 / 25SL polyurethane paint. These polyurethane paints have better effects when used.

[0014] Furthermore, the conductor is a copper wire, the purity of the copper wire is not less than 99.99%, wherein the content of Se and Te is not higher than 0.0003wt%, the content of Ag is not higher than 0.0025wt%, and the resistivity is not greater than 0.017241Ωmm 2 / m. Enameled copper wire is widely used in electronic components. For enameled copper wire above grade 180, the quality requirements for the wire are also high due to the high operating temperature.

[0015] A production process of H-class enameled wire resistant to softening and low-temperature soldering, characterized in that it comprises the following steps: (1) Wire drawing: The raw wire blank is drawn into a bare wire of the required size through pressure processing; (2) Annealing: Perform protective bright annealing on the bare wire; (3) Cooling and cleaning: Use circulating water at the exit of the annealing furnace to cool and clean the bare wire after annealing, and then blow dry; (4) Painting and curing: The cleaned bare wire is introduced into the painting oven area. After each coat of paint is applied, it is sent to the oven for baking and curing. After it comes out of the oven and is cooled by cold wind, it returns to the painting area and repeats the next painting step. (5) After the paint is cured, the enameled wire is taken out of the oven for cooling and winding to obtain H-grade enameled wire that is resistant to softening and low-temperature soldering.

[0016] Through the above technical scheme, the initial raw wire blank is drawn into the required size; then the wire grain structure is regulated by annealing to obtain better elongation and springback angle; cooling and cleaning are carried out to avoid high-temperature oxidation, remove grease and other pollutants on the surface of the wire, and ensure good adhesion between the paint layer and the wire; finally, the polyurethane paint layer is coated after painting and curing to obtain H-grade enameled wire with high softening resistance and low-temperature soldering.

[0017] Furthermore, the pH value of the wire drawing oil used in the wire drawing is 7-9, and the concentration of the wire drawing oil when used is 2-9%. The concentration of the wire drawing oil can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or a value between any two of the above numerical ranges. Preferably, the concentration of the wire drawing oil is 7%-9% for medium drawing, 4%-6% for small drawing, and 2%-4% for micro drawing.

[0018] Furthermore, during annealing, the inlet temperature of the annealing furnace is controlled to be 470℃~510℃, the center temperature is 450℃~490℃, and the outlet temperature is 440℃~480℃. This temperature range can fully anneal the copper conductor, so that the product has better elongation and rebound angle.

[0019] Furthermore, the temperature of circulating water in cooling and cleaning is 40℃~50℃, and the conductivity of circulating water is less than 10us / cm. The temperature of the wire is high after annealing, and it is very easy to be oxidized at high temperature when in contact with air, so it needs to be immediately put into cooling circulating water for cooling.

[0020] Furthermore, during the paint curing, the bare wire is introduced into the paint baking furnace area at a speed of 300m / min~350m / min, the furnace inlet temperature is 200℃~250℃, the furnace center is 330℃~400℃, and the furnace outlet temperature is 400℃~450℃.

[0021] Furthermore, a circulating catalytic-waste discharge process is set up during paint curing, so that the excess components of the paint are evaporated into gas in the oven, which is then discharged after catalytic combustion to generate carbon dioxide and water vapor. The combustion heat is used as a heat source for the oven, and some of the unreacted gases are recycled for catalytic reaction again.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention selects H-grade heat-resistant polyurethane paint as the primer and self-lubricating polyurethane paint as the topcoat to ensure the thermal stability of the enameled wire in a high temperature environment, and has a self-lubricating function, does not require a special oiling process, saves production costs, and improves production efficiency. By using high-quality copper materials, a reasonably optimized combination of heat-resistant insulating paint and self-lubricating insulating paint, and an optimized painting and curing process, combined with wire drawing, varnishing processes and recycling waste discharge technology, continuous production is carried out on the enameling machine, the enameled wire is resistant to softening and low temperature and can be directly welded, achieving 430℃ 5s multi-strand solder penetration without slag, avoiding potential damage to the insulation layer during welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The process flow chart of an embodiment of the present invention.

[0024] Figure 2 This is the infrared spectrum of the paint layer of the product of Example 1 of the present invention.

[0025] Figure 3 This is the infrared spectrum of the paint layer of Comparative Example 1.

[0026] Figure 4 This is a soldering effect diagram of the enameled wire in Example 1 of the present invention; wherein, Figure 4-1 This is a view of the tin liquid surface of 400 strands of enameled wire soldered at 430℃ for 5s; Figure 4-2 This is the surface view of the bundle of 400 strands of enameled wire soldered at 430℃ for 5s; Figure 4-3 This is an overall view of 400 strands of enameled wire being soldered at 430°C for 5 seconds.

[0027] Figure 5 This is a soldering effect diagram of the enameled wire of Example 2 of the present invention; wherein, Figure 5-1 This is a view of the tin liquid surface of 400 strands of enameled wire soldered at 430℃ for 5s; Figure 5-2 This is the surface view of the bundle of 400 strands of enameled wire soldered at 430℃ for 5s; Figure 5-3 This is an overall view of 400 strands of enameled wire being soldered at 430°C for 5 seconds.

[0028] Figure 6 This is a soldering effect diagram of the enameled wire of Comparative Example 1 of the present invention; wherein, Figure 6-1 This is a view of the tin liquid surface of 400 strands of enameled wire soldered at 430℃ for 5s; Figure 6-2 This is the surface view of the bundle of 400 strands of enameled wire soldered at 430℃ for 5s; Figure 6-3 This is an overall view of 400 strands of enameled wire being soldered at 430°C for 5 seconds.

[0029] Figure 7 This is a soldering effect diagram of the enameled wire of Comparative Example 2 of the present invention; wherein, Figure 7-1 This is a view of the tin liquid surface of 400 strands of enameled wire soldered at 430℃ for 5s; Figure 7-2 This is the surface view of the bundle of 400 strands of enameled wire soldered at 430℃ for 5s; Figure 7-3 This is an overall view of 400 strands of enameled wire being soldered at 430°C for 5 seconds.

[0030] Figure 8 This is a soldering effect diagram of the enameled wire of comparative example 3 of the present invention; wherein, Figure 8-1 This is a view of the tin liquid surface of 400 strands of enameled wire soldered at 430℃ for 5s; Figure 8-2 This is the surface view of the bundle of 400 strands of enameled wire soldered at 430℃ for 5s; Figure 8-3 This is an overall view of 400 strands of enameled wire being soldered at 430°C for 5 seconds. DETAILED DESCRIPTION

[0031] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. Unless the context otherwise clearly indicates the opposite, the singular form used herein is also intended to include the plural form. It should also be understood that the term "comprising" does not specifically refer to a certain characteristic, field, integer, step, action, element and / or component, but excludes the existence or addition of other characteristics, fields, integers, steps, actions, elements, components and / or groups.

[0032] If a part is described as being "on" another part, it may be directly on the other part or there may be other parts therebetween. When a part is described as being "directly on" another part, there may be no other parts therebetween.

[0033] Although not otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those commonly understood by those skilled in the art. Terms with definitions in dictionaries should be interpreted as having the same meaning as those disclosed in the relevant technical literature and this article, and should not be interpreted in an idealized or overly formal sense.

[0034] The present invention provides a softening-resistant low-temperature solder H-class enameled wire and a production process thereof. The specific process flow is shown in Figure 1 As shown below. Figure 1 Provide specific instructions.

[0035] The enameled wire is composed of a conductor and a coating, wherein the coating includes a primer coated on the surface of the conductor and a top coating coated on the primer. The primer is a H-grade heat-resistant polyurethane paint coating with a solid content of 25% to 30% and a viscosity of DIN4#20s to 30s; the top coating is a self-lubricating polyurethane paint coating with a solid content of 23% to 28% and a viscosity of DIN4#15s to 25s. The conductor is preferably made of high-quality hard copper material, with a lead diameter of TR2.0mm to 2.6mm, a purity of not less than 99.99%, wherein the mass fraction of selenium Se and tellurium Te is not higher than 0.0003%, the mass fraction of silver Ag is not higher than 0.0025%, and the final copper rod resistivity is not greater than 0.017241Ωmm 2 / m. The insulating paint selects H-grade heat-resistant polyurethane paint with outstanding high temperature resistance as the heat-resistant insulating layer, brand 215 / 28S or 56 / 28LS; self-lubricating polyurethane paint is used as the lubricating insulating layer, brand STU56 / 25SL. This combination can promote the formation of a good interface with the solder and improve the welding strength.

[0036] Wire drawing: After the conductor and insulating paint are selected, the copper material is drawn in sequence through medium drawing, small drawing and micro drawing by a small amount of multiple drawing method, and finally drawn to 0.080mm~0.150mm bare wire, ensuring that the bare wire has excellent softness and elongation. In order to prevent demulsification and stratification during use, improve the lubrication effect, and thus improve the surface finish of the copper wire, the pH value of the wire drawing oil is controlled at 7~9, and the concentration of the wire drawing oil is controlled at 7%~9% for medium drawing, 4%~6% for small drawing, and 2%~4% for micro drawing. During the wire drawing process, the medium drawing speed is 800m / min~1000m / min, the small drawing speed is 1200m / min~1500m / min, and the micro drawing speed is 1600m / min~2000m / min.

[0037] Annealing: The bare wire is annealed in an annealing furnace at a speed of 300m / min~350m / min to soften the copper wire. The inlet temperature of the annealing furnace is set to 470℃~510℃, the center temperature is 450℃~490℃, and the outlet temperature is 440℃~480℃. This temperature range can fully anneal the copper conductor and allow the product to have better elongation and rebound angle. If the annealing temperature is too low, incomplete annealing will reduce the adsorption of wire ions to the paint liquid during the painting process. If the temperature is higher than this, it will easily lead to coarsening of the copper conductor grains, and a significant decrease in tensile strength and elongation.

[0038] Cooling and cleaning: The temperature of the copper wire is high after annealing, and it is very easy to oxidize at high temperature when in contact with air. It needs to be immediately cooled and cleaned in the cooling circulating water, and then blown dry. Connect a cooling water tank at the outlet of the annealing furnace to prevent the copper wire from oxidizing, and thoroughly remove grease and other pollutants on the surface of the copper wire to ensure good adhesion between the paint layer and the copper wire. The temperature of the circulating deionized water is 40℃~50℃. If the cooling water temperature is too high, it is easy to cause the copper wire to oxidize during the cooling process; if it is too low, the surface of the copper wire will carry more water and it will not be easy to be blown dry. The painting process is prone to produce paint film particles and wire hair, which affects the painting effect. In addition, in order to reduce the secondary pollution of ions in the water to the copper conductor, the conductivity of the circulating water is less than 10us / cm.

[0039] Painting: The bare wire products processed in the previous step are passed through the painting area, and 7~8 coats of H-grade heat-resistant polyurethane paint are applied on the surface of the copper wire as a heat-resistant insulation layer by using a multi-coat painting method; 1~2 coats of self-lubricating polyurethane paint are used as an insulating lubricating layer to prevent cracking during transportation and use. Multi-coat painting can promote the subsequent cross-section inner layer paint film to solidify fully and evenly. Too thick a paint film will increase the melting time of the welding process, resulting in a long welding time; too thin a paint film thickness is prone to paint peeling and tin leakage. The total thickness of the paint film after painting is between 0.018mm and 0.028mm, which can significantly increase the breakdown voltage value and reduce the dispersion of the breakdown voltage.

[0040] Curing: It is an important step in the painting process. After each coat of paint is applied, it is sent to the oven for baking and curing. After leaving the oven, it is cooled by cold wind and returned to the painting area. The painting and curing steps are repeated until the painting and baking procedures are completed. A low curing temperature will lead to insufficient curing, affecting the thermal shock performance and softening breakdown performance; a high curing temperature is conducive to improving the thermal shock performance, but the softening breakdown performance decreases and is not conducive to the soldering process. In combination with the raw materials used in this patent, the wire feeding speed is set to 300m / min~350m / min, the oven inlet temperature is 200℃~250℃, the oven center is 330℃~400℃, and the temperature outlet temperature is 400℃~450℃, which can effectively improve the thermal shock performance and softening breakdown performance and reduce the soldering temperature. Furthermore, a circulating catalytic-waste discharge function is set in the oven, and the excess components in the paint solvent evaporate into gas in the oven, which is catalytically burned by the catalyst, and the generated harmless gas is discharged from the reactor through the exhaust fan. The unreacted gas is catalytically reacted again through the cycle until the reaction is complete and discharged from the reactor. The heat energy generated by the combustion reaction can be used as a heat source for baking the paint film. The circulating fan speed is 800rpm~1600rpm, and the exhaust fan speed is 1200rpm~2500rpm.

[0041] Cooling and winding: After the cured enameled wire is run out of the oven, it is subjected to impurity absorption and cooling procedures to ensure that the paint film does not adhere to impurities and the enameled wire is stably cooled to 50℃~60℃; then the wire winding machine is used to wind the wire after the cooling treatment, and the enameled wire is neatly arranged on the wire drum. At this point, the required high softening resistance and low temperature solder H-grade enameled wire is completed.

[0042] The following is an example of a preferred specific implementation.

[0043] Example 1

[0044] This embodiment provides a production process for H-class enameled wire resistant to softening and low temperature soldering, and the specific preparation steps are as follows: 1) Select high-quality hard copper material: The selected copper material is high-quality copper wire with good conductivity and mechanical strength. The inlet wire diameter is set to TR2.60mm, the purity is greater than 99.99%, the mass fraction of selenium Se and tellurium Te is not more than 0.0003%, the mass fraction of silver Ag is not more than 0.0025%, and the final copper rod resistivity is not more than 0.017241Ωmm 2 / m.

[0045] 2) Insulating paint selection: Select H-grade heat-resistant polyurethane paint with outstanding high temperature resistance as the heat-resistant insulating layer, brand 215 / 28S, total solid content 28%, viscosity DIN4# 27s, which can promote the formation of a good interface with solder and improve welding strength; self-lubricating polyurethane paint as the lubricating insulating layer, brand STU56 / 25SL, solid content 25%, viscosity DIN4# 22s.

[0046] 3) Wire drawing: Select a suitable wire drawing die, and use a small amount of multiple stretching method to sequentially draw the copper material through medium drawing, small drawing, and micro drawing, and draw the copper rod to a bare wire of 0.10mm to ensure that the bare wire has excellent softness and elongation. During the wire drawing process, use YF-107 wire drawing oil (purchased from Yutuo Technology Co., Ltd.), and adjust the concentrations of medium drawing, small drawing, and micro drawing oil to 8%, 5%, and 3% respectively; the pH value of the wire drawing oil is 8, the medium drawing speed is 900m / min, the small drawing speed is 1300m / min, and the micro drawing speed is 1800m / min.

[0047] 4) Annealing: Pass the bare wire through the annealing furnace at a speed of 320m / min to soften the copper wire. The annealing inlet temperature is set to 490℃, the annealing center temperature is set to 470℃, and the annealing outlet temperature is 460℃.

[0048] 5) Cooling and cleaning: After annealing, the temperature of the copper wire is high, and it is very easy to oxidize at high temperature when in contact with air. It needs to be immediately cooled in the cooling circulating water. The temperature of the circulating deionized water is 45°C. In order to reduce the secondary pollution of ions in the water to the copper conductor, the conductivity of the circulating water is less than 10us / cm.

[0049] 6) Painting: The bare wire products processed in the previous step are passed through the painting area, and the multi-pass painting method is used to apply 8 coats of H-grade heat-resistant polyurethane paint as a heat-resistant insulation layer and 1 coat of self-lubricating polyurethane paint as an insulation lubricating layer on the surface of the copper wire to prevent cracking during transportation and use. After multiple coats of painting, the total thickness of the paint film is 0.021mm, the primer film thickness is 0.01925mm, and the topcoat film thickness is 0.00175mm, which can significantly increase the breakdown voltage value and reduce the dispersion of the breakdown voltage.

[0050] 7) Curing: Curing is an important part of the painting process. After each coat of paint is applied, it is sent to the oven for baking and curing. After being cooled by cold wind, it returns to the painting area and repeats steps 6) to 7) until the painting and baking program is completed. Combined with the raw materials used, the wire feeding speed is set to 320m / min, the oven inlet temperature is 220℃, the oven center is 360℃, and the oven outlet temperature is 425℃, which can effectively improve the thermal shock performance and softening breakdown performance and reduce the solder temperature. Furthermore, a circulating catalytic-waste discharge function is set in the oven. The excess components in the paint solvent evaporate into gas in the oven, and the catalyst catalytic combustion is carried out. The generated harmless gas is discharged from the reactor through the exhaust fan. The unreacted gas is catalytically reacted again after circulation until the reaction is complete and discharged from the reactor. The heat energy generated by the combustion reaction can be used as a heat source for paint film baking. The circulating fan speed is 1300rpm, and the exhaust fan speed is 1800rpm.

[0051] 8) Cooling: After the cured enameled wire runs out of the oven, it is subjected to impurity removal and cooling procedures to ensure that the paint film does not adhere to impurities and the enameled wire is stably cooled to 50℃~60℃.

[0052] 9) Wire taking-up: Use a wire taking-up machine to take up the wire after cooling treatment, and wind the enameled wire neatly on the reel.

[0053] Example 2

[0054] The present embodiment provides a production process for softening-resistant low-temperature solder H-grade enameled wire. The specific steps are basically the same as those in Example 1. The difference from Example 1 is that the primer layer uses a polyurethane paint with a brand of 56 / 28LS, a total solid content of 27.5%, a viscosity of DIN4# 23 s, and a total paint film thickness of 0.021 mm after multiple coats of coating, a primer film thickness of 0.01925 mm, and a topcoat film thickness of 0.00175 mm.

[0055] Comparative Example 1

[0056] The present comparative example provides a production process for softening-resistant low-temperature solder H-grade enameled wire, and the specific steps are basically the same as those in Example 1. The difference from Example 1 is that the primer layer uses a polyurethane paint with a brand of 1756 / 32, a total solid content of 32%, and a viscosity of DIN4# 34s; the top coating uses a self-lubricating nylon paint (purchased from Dingyuan Chengyu Electrical Materials Co., Ltd.), with a solid content of 8.5% and a viscosity of DIN4# 38s.

[0057] Comparative Example 2

[0058] This comparative example provides a production process for softening-resistant low-temperature solder H-grade enameled wire, and the specific steps are basically the same as those of Example 1. The difference from Example 1 is that the furnace inlet temperature is set to 220°C, the furnace center temperature is set to 450°C, and the furnace outlet temperature is set to 500°C.

[0059] Comparative Example 3

[0060] The present comparative example provides a production process for softening low-temperature solder H-grade enameled wire. The specific steps are basically the same as those in Example 1. The difference from Example 1 is that in the painting step, 10 coats of H-grade heat-resistant polyurethane paint are applied to the surface of the copper wire as a heat-resistant insulation layer and 1 coat of self-lubricating polyurethane paint is applied as an insulating lubricating layer. After multiple coats of paint, the total thickness of the paint film is 0.03 mm, the primer film thickness is 0.0275 mm, and the topcoat film thickness is 0.0035 mm.

[0061] The enameled wire products of Examples 1-2 of the present invention and Comparative Examples 1-3 were subjected to performance tests, and the relevant performance comparisons are shown in Table 1 below.

[0062] Table 1.

[0063]

[0064] It can be seen from the test results in Table 1 that the surface of the enameled wire of the present invention is smooth and continuous without spots, bubbles and impurities. The enameled wire has good soldering performance and can achieve low-temperature direct soldering. A single enameled wire can be soldered through at 320°C in 2 seconds, and multiple enameled wires can be soldered through at 430°C in 5 seconds. It also has excellent softening resistance and heat shock resistance.

[0065] Depend on Figure 2 and Figure 3 It can be seen from the infrared spectrum of the paint layer that the peak diagrams of the two are similar, but the number of peaks and the peak value are different. The embodiment of the present invention has a peak at 2900cm -1 ~3600cm -1 There are multiple peaks in the region, which indicates that the contents of various substances in the paint film are different.

[0066] Depend on Figure 4 and Figure 5 It can be seen that 400 strands of enameled wires prepared in Example 1 and Example 2 can be soldered through at 430° C. for 5 seconds, with only a small amount of black slag on the tin liquid surface, and the wire ends of the bundles are white without any black slag residue.

[0067] Depend on Figure 6 It can be seen that after using different paint layer materials in Comparative Example 1, the surface of the enameled wire occasionally has surface particles, and the 400 strands of enameled wire cannot be soldered through under the conditions of 430°C and 5s. The paint residue on the tin liquid surface is too much and black and concentrated, and there is also paint residue attached to the wire ends. Figure 7It can be seen that in Comparative Example 2, different curing conditions were used, and the 400 strands of enameled wire could not be welded through at 430°C and 5s, and a small amount of paint film remained undecomposed; a small amount of paint residue was black and scattered on the tin liquid surface, and the surface of the bundle was yellow with paint residue attached. Figure 8 It can be seen that in Comparative Example 3, different paint film thickness conditions were used, and the 400-strand enameled wire could not be welded through at 430°C and 5s, and part of the remaining paint film was not decomposed; there was too much paint residue on the tin liquid surface, the paint residue was black and scattered, and the wire surface was bright but with a small amount of paint residue attached.

[0068] The present invention can be implemented in various ways and is not limited to the above-mentioned embodiments and / or examples. A person skilled in the art can understand that the present invention can be implemented in other specific ways without changing the technical concept or essential features of the present invention. Therefore, it should be understood that the above-mentioned embodiments and / or examples are exemplary and are not intended to limit the present invention.

Claims

1. A H-class enameled wire resistant to softening and low temperature soldering, characterized in that: The H-class enameled wire is composed of a conductor and a coating, wherein the coating comprises a primer coated on the surface of the conductor and a top coating coated on the primer, wherein the primer is obtained by coating at least 7 coats of an H-class heat-resistant polyurethane paint having a solid content of 25% to 30% and a viscosity of DIN4# 20s to 30s; and the top coating is obtained by coating a self-lubricating polyurethane paint having a solid content of 23% to 28% and a viscosity of DIN4# 15s to 25s.

2. The H-class enameled wire resistant to softening and low temperature soldering according to claim 1, characterized in that: The total thickness of the paint film of the base coating and the top coating is 0.018 mm to 0.028 mm, and the thickness ratio of the paint film thickness of the base coating to the paint film thickness of the top coating is 11 to 12.

3. The H-class enameled wire resistant to softening and low temperature soldering according to claim 1, characterized in that: The paint film thickness of the primer layer is the layer thickness of 7 to 8 coats of H-grade heat-resistant polyurethane paint, and the paint film thickness of the top coating layer is the layer thickness of 1 to 2 coats of self-lubricating polyurethane paint.

4. The H-class enameled wire resistant to softening and low temperature soldering according to claim 1, characterized in that: The H-grade heat-resistant polyurethane paint is a 215 / 28S or 56 / 28LS polyurethane paint, and the self-lubricating polyurethane paint is a STU56 / 25SL polyurethane paint.

5. The H-class enameled wire resistant to softening and low temperature soldering according to claim 1, characterized in that: The conductor is a copper wire, the purity of which is not less than 99.99%, wherein the content of Se and Te is not higher than 0.0003wt%, the content of Ag is not higher than 0.0025wt%, and the resistivity is not greater than 0.017241Ωmm 2 / m.

6. A production process for a softening-resistant low-temperature solder H-grade enameled wire according to any one of claims 1 to 5, characterized in that: The steps include: (1) Wire drawing: The raw wire blank is drawn into a bare wire of the required size through pressure processing; (2) Annealing: Perform protective bright annealing on the bare wire; (3) Cooling and cleaning: Use circulating water at the exit of the annealing furnace to cool and clean the bare wire after annealing, and then blow dry; (4) Painting and curing: The cleaned bare wire is introduced into the painting and baking oven area. After each coat of paint is applied, it is sent into the baking oven for baking and curing. After it comes out of the baking oven, it is cooled by cold wind and returned to the painting area. The painting and curing steps are repeated until the paint baking is completed; (5) After the paint is cured, the enameled wire is taken out of the oven for cooling and winding to obtain H-grade enameled wire that is resistant to softening and low-temperature soldering.

7. The production process of a softening-resistant low-temperature solder H-grade enameled wire according to claim 6, characterized in that: During annealing, the inlet temperature of the annealing furnace is controlled at 470°C ~ 510°C, the center temperature is controlled at 450°C ~ 490°C, and the outlet temperature is controlled at 440°C ~ 480°C.

8. The production process of a softening-resistant low-temperature solder H-class enameled wire according to claim 6, characterized in that: The circulating water temperature during cooling and cleaning is 40℃~50℃, and the circulating water conductivity is less than 10us / cm.

9. The production process of a softening-resistant low-temperature solder H-class enameled wire according to claim 6, characterized in that: During paint curing, the bare wire is introduced into the paint baking furnace area at a speed of 300m / min~350m / min. The furnace inlet temperature is 200℃~250℃, the furnace center is 330℃~400℃, and the furnace outlet temperature is 400℃~450℃.

10. The production process of a softening-resistant low-temperature solder H-class enameled wire according to claim 6, characterized in that: During the paint curing, a circulating catalytic-waste discharge process is set up to evaporate the excess paint components into gas in the drying furnace, which is then discharged after catalytic combustion. The combustion heat is used as the heat source of the drying furnace, and the gas that has not reacted completely is circulated for catalytic reaction again.

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