Corona-resistant variable-frequency self-adhesive wire and preparation method thereof

Abstract

The invention discloses a corona-resistant variable-frequency self-adhesive wire and a preparation method thereof, the method comprises a copper conductor and a paint film layer which is coated on the copper conductor and is obtained by curing under the condition of the same temperature and the same furnace, and the paint film layer comprises an inner corona-resistant insulating paint layer and an outer self-adhesive layer; and the self-adhesive layer is obtained by coating and curing self-adhesive insulating paint of thermal bonding type aromatic polyamide. The paint film layer of the self-adhesive wire can be baked and cured on the copper conductor at the same temperature and in the same furnace, the technological process is saved, the cost is saved, the re-softening temperature of the self-adhesive wire is high, and the self-adhesive wire can meet the use environment of high-heat-resistance special working conditions.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of enameled wire, and particularly relates to a corona-resistant variable-frequency self-adhesive wire and a preparation method thereof. BACKGROUND

[0002] In recent years, with the rapid development of electronic technology, variable-frequency electronic and electrical products such as audio equipment and refrigeration equipment are increasingly widely used in life. However, the traditional variable-frequency wire is relatively cumbersome in installation and use, and requires additional fixing devices or complex connection steps such as dip coating treatment, and the dip coating process easily releases harmful solvent gas.

[0003] A patent application with the publication number CN109659078A discloses a high-PDIV corona-resistant enameled wire and a preparation process thereof. The high-PDIV corona-resistant variable-frequency enameled wire comprises a core conductor and a paint layer, and the paint layer is composed of a first paint layer, a second paint layer and a third paint layer. The first paint layer is a polyimide paint film with a dielectric constant less than 3.3; the second paint layer is a variable-frequency polyester imine paint film and / or a variable-frequency polyamide-imide paint film; and the third paint layer is a polyamide-imide paint film or a polyimide paint film with a dielectric constant less than 3.3. The high-PDIV corona-resistant variable-frequency enameled wire is formed by using a high-speed continuous drawing and coating machine to stretch, coat insulating paint and sequentially bake and solidify the core rod. The high-PDIV corona-resistant enameled wire and the preparation process thereof provided by the application realize that the PDIV value of the high-PDIV corona-resistant enameled wire is greater than 1250V, and the measured life time of the high-frequency pulse resistance characteristic is 20-30 hours, through the design of the coating process, the comprehensive application of multiple paints and the adjustment of the oven process parameters. However, the corona-resistant enameled wire disclosed in the patent application needs to be subjected to complex dip coating treatment.

[0004] Although the existing self-adhesive wire simplifies the coil forming process, the adhesion performance is prone to decrease due to changes in environmental temperature and humidity during long-term use, resulting in unstable line structure. In addition, the adaptability of ordinary enameled wire or ordinary self-adhesive wire to different frequency motors is poor, and there is unstable signal transmission in a variable-frequency environment, which affects the transmission efficiency and accuracy of the signal. The pulse voltage generated by the variable frequency and the dielectric heating have a destructive effect on the paint film of the enameled wire, and the enameled wire is prone to inter-turn breakdown during long-term use. Neither the single variable-frequency wire nor the single self-adhesive wire can meet the diversified industrial and civil needs.

[0005] In addition, most of the self-adhesive wires sold on the market currently adopt the same-speed different-temperature or double-oven production process to solve the cross-linking and solidification between different characteristic paints, so that the enameled wire reaches the best solidification state. However, this method has high energy consumption and is not conducive to energy saving and emission reduction.

[0006] Therefore, to solve the problems of complicated installation and use of the existing variable frequency wire, unstable signal transmission of the self-adhesive wire, easy reduction of the self-adhesive performance, and poor adaptability to different frequencies, it is an urgent need in the current technical field to develop a low-energy-consumption and high-benefit variable frequency self-adhesive wire which is easy to install and use, has a variable frequency function, and is produced in the same temperature and same furnace. SUMMARY

[0007] The application provides a corona-resistant variable frequency self-adhesive wire, the paint film layer of the self-adhesive wire can be baked and solidified on a copper conductor in the same temperature and same furnace, thereby saving a process flow and saving cost, and the self-adhesive wire provided by the application has a higher softening temperature again, and can meet the use environment of high heat resistance special working conditions.

[0008] The application provides a corona-resistant variable frequency self-adhesive wire, which is characterized by comprising a copper conductor and a paint film layer obtained by coating and solidifying on the copper conductor under the same temperature and same furnace, wherein the paint film layer comprises an inner corona-resistant insulating paint layer and an outer self-adhesive layer. The self-adhesive layer is obtained by coating and solidifying a heat-bonding aromatic polyamide self-adhesive insulating paint.

[0009] Preferably, the heat-bonding aromatic polyamide self-adhesive insulating paint comprises, in percentage by mass: N-methyl-2-pyrrolidone: 62-64%; Xylene: 1.0-2.0%; Cresol: 0.5-5.0%; Aromatic polyamide resin: 25-28%.

[0010] Preferably, the heat-bonding aromatic polyamide self-adhesive insulating paint provided by the application has a solid content of 25-28%.

[0011] Since the solvent of the self-adhesive insulating paint provided by the application is a high-boiling-point solvent and has high heat resistance, and the molecular formula of the aromatic polyamide provided by the application is (C6H11NO)n, which is a heat-resistant aromatic nylon, when the temperature of the solidification zone is set to 530-580 DEG C, the self-adhesive paint provided by the application still has good adhesion without carbonization, and therefore can be baked and solidified in the same temperature and same furnace as the variable frequency paint.

[0012] Preferably, the processing hot melting temperature of the heat-bonding aromatic polyamide self-adhesive insulating paint is 200-240 DEG C.

[0013] The processing temperature of the self-adhesive insulating paint coated by the hot-bonding type aromatic polyamide provided by the application is 200-240 DEG C, and the self-adhesive layer has better adhesion, the re-softening temperature of the self-adhesive layer can be as high as 180-190 DEG C, and the self-adhesive layer can meet the special working condition of high heat resistance, and the coil can be bonded and formed by baking or direct power supply, and the self-adhesive layer has excellent bonding force, heat resistance and deformation resistance, the friction coefficient of the paint film surface is small, the self-adhesive layer can meet the forming of the boneless coil product of the customer and reduce the paint immersion process of the product, greatly improve the processing efficiency of the product of the downstream customer, and make a contribution to the improvement of the environment, and the self-adhesive layer can be combined and matched with polyester imide paint and polyamide imide paint in various ways due to the unique high heat resistance, and the self-adhesive layer can meet the same temperature and same furnace production process condition.

[0014] Preferably, the copper conductor is a hard copper conductor with a diameter of 0.4 mm to 1.6 mm, an electrical resistance of 0.00826 Ω / m to 0.1407 Ω / m, and an out-of-roundness of less than or equal to 0.003, and the copper conductor is subjected to annealing treatment before being coated with paint to ensure tensile resistance.

[0015] Preferably, the corona-resistant insulating paint layer is two insulating layers, wherein the inner layer is a 200-grade polyester imide frequency conversion insulating layer, and the outer layer is a 220-grade polyamide imide frequency conversion insulating layer. Alternatively, the corona-resistant insulating paint layer is a 220-grade polyamide imide frequency conversion insulating layer. Alternatively, the corona-resistant insulating paint layer is a 240-grade aromatic polyamide layer.

[0016] Further preferably, the polyester imide frequency conversion insulating layer is obtained by coating and baking polyester imide paint, the polyester imide paint has a solid content of 38% to 41%, and the content of nano-powder shielding particles in the polyester imide paint is 1% to 10%.

[0017] The polyester imide frequency conversion insulating layer used in the application uses a 200-grade corona-resistant polyester imide paint with an actual heat resistance index as a coating layer, and has good corona resistance.

[0018] Preferably, the polyamide imide frequency conversion insulating layer is obtained by coating and baking polyamide imide paint, the polyamide imide paint has a solid content of 32% to 35%, and the content of nano-powder shielding particles in the polyamide imide paint is 5% to 9%.

[0019] Further preferably, the nano-powder shielding particles are (1) silicon dioxide: reducing dielectric loss and inhibiting partial discharge; (2) silicon carbide: resisting arc erosion (improving corona resistance by 5-8 times); and (3) TiO2 / Ag hybrid particles: Ag nanoparticles (3-5 nm) embedded in TiO2, realizing anti-corona and anti-bacterial dual functions.

[0020] Preferably, when the corona-resistant insulating paint layer is two layers of insulating layers, in the paint film layer, the thickness ratio of the polyester-imide variable-frequency insulating layer is 30%-40%, the thickness ratio of the polyimide variable-frequency insulating layer is 25%-35%, and the thickness ratio of the self-adhesive layer in the paint film layer is 35%-40%.

[0021] The polyimide variable-frequency insulating layer used in the application uses a 220-grade polyimide paint with actual heat resistance index as a coating layer, and the polyimide variable-frequency insulating layer and the polyimide variable-frequency insulating layer are used as the main insulating body, so that the enameled wire has good heat resistance grade and corona resistance.

[0022] The thickness of the polyester-imide variable-frequency insulating layer and the polyester-imide variable-frequency insulating layer is controlled, so that the variable-frequency self-adhesive wire provided by the application has high corona resistance at a reasonable cost, and the thickness of the self-adhesive layer is controlled, so that the variable-frequency self-adhesive wire provided by the application has high high-temperature resistance.

[0023] On the other hand, the application also provides a preparation method of the corona-resistant variable-frequency self-adhesive wire, comprising: Annealing the copper conductor, and coating the corona-resistant insulating paint layer and the aromatic polyamide self-adhesive insulating paint on the outer surface of the annealed copper conductor in multiple passes; After each pass, the corona-resistant insulating paint layer and the aromatic polyamide self-adhesive insulating paint are cured under the same temperature and same oven conditions to obtain a paint film layer, and in the curing process, the temperature of the curing zone is 530-580 DEG C, and the speed DV is 100-110; The paint film layer is coated with oil, and the variable-frequency self-adhesive wire is obtained.

[0024] The aromatic polyamide self-adhesive insulating paint provided by the application can still maintain good adhesion at a high temperature without carbonization, so the application accidentally discovered during a large number of tests that the temperature of 530-580 DEG C can simultaneously achieve the curing of the variable-frequency insulating paint (i.e. the corona-resistant insulating paint layer) and the self-adhesive insulating paint, and realizes the same temperature and same oven baking and curing, compared with the existing two ovens for curing the variable-frequency insulating paint and the self-adhesive paint respectively, the multiple processes are saved, the cost is saved, the efficiency is improved, and the environment is more friendly.

[0025] Preferably, during the curing process, the oven inlet temperature is 200-350 DEG C, the temperature before catalysis is 600-650 DEG C, and the temperature after catalysis is 650-700 DEG C. The temperature before catalysis refers to the temperature control process of stepwise heating of the conductor coated with insulating paint in the preheating zone before entering the main curing zone (catalytic furnace). This stage mainly completes the evaporation of solvent and the pre-crosslinking reaction of resin, and prepares for the subsequent high-temperature catalytic curing. The temperature after catalysis refers to the temperature of the main curing stage of the enameled wire in the catalytic furnace. The complete crosslinking reaction of resin is triggered by high temperature, forming a three-dimensional network structure, so that the insulating layer obtains the final performance.

[0026] Preferably, the speed DV is 100-110, and the increment between passes is 0.005-0.007 mm when coating the corona-resistant insulating paint; and the increment between passes is 0.010-0.012 mm when coating the aromatic polyamide self-adhesive insulating paint.

[0027] The application provides that, under the suitable speed DV, by controlling the increment of the corona-resistant insulating paint and the increment of the self-adhesive insulating paint, the evaporation effect of the variable-frequency paint and the self-adhesive insulating paint is better, and the failure possibility of the self-adhesive insulating paint is lower under the conditions of the same temperature, the same furnace and the production speed requirement.

[0028] Preferably, the corona-resistant insulating paint layer is polyester-imide paint and polyamide-imide paint.

[0029] Further preferably, the total coating passes are 19-25, and the overall paint film thickness is designed according to GB and can be controlled and adjusted to be 0.080-0.120 mm. The increment between passes of the polyester-imide variable-frequency paint is 0.005 mm, and the paint is re-coated after baking and curing; the overall paint film thickness is controlled to be 0.030-0.040 mm, accounting for 35-40% of the total paint film thickness. The increment between passes of the polyamide-imide variable-frequency paint is 0.005 mm, and the paint is re-coated after baking and curing; the overall paint film thickness is controlled to be 0.025-0.030 mm, accounting for 25-30% of the total paint film thickness. The increment between passes of the aromatic polyamide (nylon) self-adhesive paint is 0.010 mm, and the paint is re-coated after baking and curing; the overall paint film thickness is controlled to be 0.025-0.035 mm, accounting for 35-40% of the total paint film thickness. Under the condition of fixed temperature and speed, the application can adjust the baking degree of each paint layer by the different increments of the paint coating arranged by the mold, so that the wire performance reaches better characteristics.

[0030] Preferably, the oiling process is as follows: 1-2 layers of motor oil are coated on the surface of the enameled wire after curing by adopting the cylinder oiling method, so that the surface smoothness is increased, and the phenomenon of wire knotting in the use process of the enameled wire can be prevented.

[0031] Preferably, the process of taking up the wire is that the produced enameled wire is finally taken up in a wire reel, and then is packaged to obtain the variable frequency self-adhesive wire product meeting the performance.

[0032] Compared with the prior art, the application has the following beneficial effects: The self-adhesive enameled wire provided by the application has good self-adhesion at a higher curing temperature, so that the enameled wire can be baked and cured in the same oven as the variable frequency insulation layer, compared with single oven production, the drawing step is simplified, the electricity is saved, the energy consumption is reduced, the process control points are reduced, and the influence of various fluctuations in the production process on the product performance is minimized.

[0033] The application coats the variable frequency enameled wire, which has excellent high-frequency performance, high-temperature resistance and wear resistance, on the outer surface of the conductor, that is, the corona-resistant insulation enameled wire. Since the variable frequency enameled wire used introduces quantum nanometer shielding particles with electric shielding function in the enameled base polymer (enamel base resin), excellent electric shock resistance, partial discharge resistance and thermal stability are provided, so that the pulse high voltage can be dispersed and resolved, thereby avoiding the local ionization of the enameled wire insulation enameled film under the variable frequency high voltage, which causes the enameled film to be broken down, and improving the durability of the enameled wire. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The structural schematic diagram of the corona-resistant variable frequency self-adhesive wire provided by the application is shown in FIG. 1. Figure 2 The structural schematic diagram of the corona-resistant variable frequency self-adhesive wire provided by the application is shown in FIG. 1. Figure 3 The structural schematic diagram of the corona-resistant variable frequency self-adhesive wire provided by the application is shown in FIG. 1. DETAILED DESCRIPTION

[0035] The corona-resistant variable frequency self-adhesive wire provided by the application integrates variable frequency and self-adhesion, and meets the requirements of simplifying the installation and use process, good signal transmission stability and durability, so that the product can adapt to various complex use environments and improve the reliability of the equipment. The special formula of the self-adhesive layer enables it to maintain good adhesion in different environments, facilitating the fixation and wiring of the coil. By introducing the self-adhesive layer, the cable can be conveniently adhered to various surfaces without the need for additional fixing devices and complex connection steps, reducing the installation and use cost and improving the work efficiency. By using the conductor with high electrical conductivity and low resistance and the insulation material suitable for the variable frequency environment, the signal attenuation and distortion in the transmission process can be effectively reduced, and the normal use in the variable frequency equipment can be ensured.

[0036] The corona-resistant variable-frequency self-adhesive wire provided by the application is produced by using a new process of same-temperature and same-furnace production, which simplifies the process, saves energy, is environmentally friendly, and is efficient and stable. The process uses a single furnace for production, which simplifies the wire-drawing step, saves electricity, reduces energy consumption, reduces process control points, and reduces various fluctuations that may occur in the production process and affect the performance of the product.

[0037] The 0.4mm-1.6mm variable-frequency self-adhesive wire produced by the method provided in the embodiment of the application can be separated at a high temperature load of 200℃ / 180℃, and the room temperature load can reach 4N. Under a 20KHz frequency, a 1500V-3000V steady-state pulse voltage impact, the breakdown time is 60h-80h.

[0038] The components and ratios of the corona-resistant heat-bonding aromatic polyamide self-adhesive insulating paint FSB AN 26H provided by the application are shown in Table 1.

[0039] Table 1 shows the components and content of the corona-resistant heat-bonding aromatic polyamide self-adhesive insulating paint FSB AN 26H

[0040] Example 1: 1) Selecting a light wire conductor: the conductor is a hard copper conductor with a diameter of 0.47m, the resistance is 0.09810Ω / m, and the non-circularity is less than or equal to 0.001.

[0041] 2) Selecting paint for the paint film layer: selecting a corona-resistant polyester imine paint BP65 / 40 (solid content 39.8%), a corona-resistant polyamide imide paint BP68 / 36 (solid content 33.0%), and a self-adhesive insulating paint FSB AN 26H (solid content 26.0%) as the polyester imine variable-frequency insulating layer, the polyamide imide variable-frequency insulating layer, and the self-adhesive layer, respectively.

[0042] 3) Annealing: the 0.47mm hard copper conductor is passed through an annealing furnace, the annealing furnace uses a two-stage temperature control method, the softening 1 temperature is 520℃, and the softening 2 temperature is 460℃, and the elongation rate after annealing is 40%.

[0043] 4) Painting: using mold painting method, according to the paint solid content and 0.47 mm copper conductor painting. First, 8 layers of corona resistant polyester imide paint BP65 / 40 are applied on the surface of the copper conductor, the mold is arranged in the order of 0.500, 0.505, 0.510, 0.515, 0.520, 0.525, 0.530, 0.535, after coating, the product size increases from 0.47 mm to 0.501 mm, the thickness increases by 0.031 mm, accounting for 36.47% of the total thickness. Then 6 layers of corona resistant polyamide imide paint BP68 / 36 are applied, the mold is arranged as 0.540, 0.545, 0.550, 0.555, 0.560, 0.565, after coating, the product size increases to 0.525 mm, the polyamide imide frequency conversion insulation layer thickness is 0.024 mm, accounting for 28.24% of the total thickness. Finally, 7 layers of self-adhesive insulation paint FSB AN 26H are applied, the mold is arranged as 0.560, 0.570, 0.580, 0.590, 0.600, 0.610, 0.620, after coating, the product size increases to 0.555 mm, the self-adhesive layer thickness is 0.030 mm, accounting for 35.29% of the total thickness.

[0044] 5) Curing: after each coating, the product is baked and cured at a speed of 213 m / min through an oven. The oven inlet temperature is 300°C, the curing zone temperature is 550°C, the pre-catalysis temperature is 600°C, and the post-catalysis temperature is 660°C. Through this series of speed and temperature design, the solvents in each paint are fully evaporated, and the self-adhesive layer is not damaged due to high baking temperature, so that the corona resistance and self-adhesion of the paint film after curing are effectively maintained.

[0045] Oil coating: using drum oil coating method, 1 layer of motor oil is applied on the surface of the cured enameled wire to increase the surface smoothness and prevent the enameled wire from knotting during use.

[0046] Winding: finally, the produced enameled wire is wound on a wire reel for packaging to obtain the finished variable frequency self-adhesive wire product with the structure as shown in Figure 1 The paint film layers wrapped around the copper conductor are in the order of 200 grade polyester imide variable frequency insulation layer, 220 grade polyamide imide variable frequency insulation layer and 200-240 grade self-adhesive layer from inside to outside.

[0047] The test results of the variable frequency self-adhesive wire prepared according to the present embodiment are shown in Table 2.

[0048] Example 2: The painting passes of the polyester imine variable frequency insulating layer, the polyamide imide variable frequency insulating layer and the self-adhesive layer in the painting process are adjusted from 8+6+7 to 7+7+7, and other process production technologies, raw materials and auxiliary materials are the same as those in Example 1. Among them, according to the paint solid content and the painting on the 0.47 mm copper conductor. First, 7 passes of corona-resistant polyester imine paint BP65 / 40 are applied on the surface of the copper conductor, the mold is arranged in the order of 0.500, 0.505, 0.510, 0.515, 0.520, 0.525, 0.530, and after painting, the product size increases from 0.47 mm to 0.497 mm, with an increase of 0.027 mm, accounting for 31.76% of the total thickness.

[0049] Then 7 passes of corona-resistant polyamide imide paint BP68 / 36 are applied, the mold is arranged as 0.535, 0.540, 0.545, 0.550, 0.555, 0.560, 0.565, and after painting, the product size increases to 0.525 mm, the thickness of the polyamide imide variable frequency insulating layer is 0.028 mm, accounting for 32.95% of the total thickness. Finally, 7 passes of self-adhesive insulating paint FSB AN 26H are applied, the mold is arranged as 0.560, 0.570, 0.580, 0.590, 0.600, 0.610, 0.620, and after painting, the product size increases to 0.555 mm, the thickness of the self-adhesive layer is 0.030 mm, accounting for 35.29% of the total thickness, and a 200-grade polyamide imide composite polyester imine variable frequency self-adhesive wire product with a 0.47 mm national standard-2 paint film is prepared, and the structure of the finished product is as shown in Figure 1 .

[0050] The test results of the variable frequency self-adhesive wire prepared according to the present embodiment are shown in Table 2.

[0051] Example 3: The paint film layer uses paint selection: respectively select corona-resistant polyester imine paint 598 / 40 (solid content 38.2%), corona-resistant polyamide imide paint 595 / 34CR (solid content 33.0%) and self-adhesive insulating paint FSB AN 26H (solid content 26.0%) as the polyester imine variable frequency insulating layer, the polyamide imide variable frequency insulating layer and the self-adhesive layer, and other process production technologies, raw materials and auxiliary materials are the same as those in Example 2. The thickness and proportion of the polyester imine variable frequency insulating layer, the polyamide imide variable frequency insulating layer and the self-adhesive layer are respectively: 0.03 mm (accounting for 35.29%), 0.024 mm (accounting for 28.24%), 0.031 mm (accounting for 36.47%), and a 200-grade polyamide imide composite polyester imine variable frequency self-adhesive wire product with a 0.47 mm national standard-2 paint film is prepared, and the structure of the finished product is as shown in Figure 1 .

[0052] The test results of the variable frequency self-adhesive wire prepared according to the present embodiment are shown in Table 2.

[0053] Example 4: Paint selection for paint film layers: Resistive polyamide-imide paint 595 / 34CR (solid content 33.0%) and self-adhesive insulating paint FSB AN 26H (solid content 26.0%) were selected as the polyamide-imide frequency conversion insulating layer and the self-adhesive layer, respectively.

[0054] Other process production processes, raw materials and auxiliary materials are the same as those in Example 2. The number of passes for coating the polyamide-imide frequency conversion insulating layer is the same as the total number of passes for coating the polyester-imide frequency conversion insulating layer and the polyamide-imide frequency conversion insulating layer in Example 2, and the mold arrangement for coating the polyester-imide frequency conversion insulating layer and the polyamide-imide frequency conversion insulating layer is the same. The thickness and proportion of the polyamide-imide frequency conversion insulating layer and the self-adhesive layer are 0.055 mm (64.71% of the proportion) and 0.030 mm (35.29% of the proportion), respectively. A 220-grade polyamide-imide frequency conversion self-adhesive wire product with a 0.47 mm national standard-2 paint film was prepared. The structure of the prepared product is shown in Figure 2 The paint film layer wrapping the copper conductor is sequentially composed of a 220-grade polyamide-imide frequency conversion insulating layer and a 200-240-grade self-adhesive layer from the inside to the outside.

[0055] The test results of the frequency conversion self-adhesive wire prepared according to the present example are shown in Table 2.

[0056] Example 5: Paint selection for paint film layers: Resistive 240-grade aromatic polyamide-imide paint (solid content 25.0%) and self-adhesive insulating paint FSB AN 26H (solid content 26.0%) were selected as the aromatic polyamide-imide frequency conversion insulating layer and the self-adhesive layer, respectively.

[0057] Other process production processes, raw materials and auxiliary materials are the same as those in Example 2. The number of passes for coating the aromatic polyamide-imide frequency conversion insulating layer is the same as the total number of passes for coating the polyester-imide frequency conversion insulating layer and the polyamide-imide frequency conversion insulating layer in Example 2, and the mold arrangement for coating the polyester-imide frequency conversion insulating layer and the polyamide-imide frequency conversion insulating layer is the same. The thickness and proportion of the aromatic polyamide-imide frequency conversion insulating layer and the self-adhesive layer are 0.055 mm (64.71% of the proportion) and 0.030 mm (35.29% of the proportion), respectively. A 240-grade aromatic polyamide-imide frequency conversion self-adhesive wire product with a 0.47 mm national standard-2 paint film was prepared. The structure of the prepared product is shown in Figure 3 The paint film layer wrapping the copper conductor is sequentially composed of a 240-grade aromatic polyamide-imide frequency conversion insulating layer and a 200-240-grade self-adhesive layer from the inside to the outside.

[0058] The test results of the frequency conversion self-adhesive wire prepared according to the present example are shown in Table 2.

[0059] Comparative Example 1: The oven inlet temperature in the curing process was set to 380°C, the curing zone temperature was set to 600°C, and the other process production technology, raw and auxiliary materials, and paint film thickness were the same as in Example 1, to produce a 200-grade polyamide-imide composite polyester-imide frequency conversion self-adhesive wire product with a gauge of 0.47 mm and a GB-2 paint film.

[0060] The test results of the frequency conversion self-adhesive wire produced according to this example are shown in Table 2.

[0061] From the test results in Table 2, it can be seen that: 1. Using a combination of 200-grade corona-resistant polyester-imide paint with a solid content of 38% to 41%, 220-grade corona-resistant polyamide-imide paint with a solid content of 32% to 35%, and aromatic self-adhesive insulating paint with a solid content of 25% to 28%, a polyamide-imide composite polyester-imide frequency conversion self-adhesive wire with good heat resistance can be produced. 2. Compared with Example 1, the number of paint coating passes in Example 2 was adjusted from 8+6+7 to 7+7+7, the thickness ratio of the polyester-imide frequency conversion insulating layer was reduced from 36.47% to 31.76%, the thickness ratio of the polyamide-imide frequency conversion insulating layer was increased from 28.24% to 32.94%, and the thickness of the self-adhesive layer remained unchanged at 35.29%. Under a 2000V steady-state impulse voltage impact, the service life time was significantly increased from 65h to 76h. Due to the unique properties of the nanomaterials in the polyamide-imide frequency conversion insulating paint, the thickness ratio of the corona-resistant polyamide-imide paint was increased, and the anti-corona time was relatively increased (an increase of 0.001mm in the ratio increased the anti-corona time by more than 1 hour), and the self-adhesive performance did not change significantly.

[0062] 3. In Example 3, the same type of insulating paint was used to replace the production, with the solid content of the corona-resistant polyester-imide paint being 1.8% lower than in Example 1 and the ratio being 4% lower. Under a 2000V steady-state impulse voltage impact, the service life time was slightly shortened, and the self-adhesive performance did not change significantly.

[0063] 4. Compared with Example 2, in Example 4, the corona-resistant insulating paint layer was completely replaced by a polyamide-imide frequency conversion insulating layer, and the heat resistance grade was significantly increased. Under a 2000V steady-state impulse voltage impact, the service life time was significantly increased from 76h to 85h, and the self-adhesive performance did not change significantly.

[0064] 5. Compared with Example 2, in Example 5, the corona-resistant insulating paint layer was completely replaced by a corona-resistant 240-grade aromatic polyamide-imide paint, and the heat resistance grade was significantly increased. Under a 2000V steady-state impulse voltage impact, the service life time was significantly increased from 76h to 120h, and the self-adhesive performance did not change significantly.

[0065] 6. The same conditions as in Example 1 were used for each material provided by Comparative Example 1, except that the oven inlet and curing temperature were increased to the upper limit of the range set by the patent by 30°C, the corona resistance did not change significantly, the adhesion performance still met the national standard requirements, but the load separation after bonding was significantly reduced, mainly because the self-adhesive paint was sensitive to high temperature heating, which exceeded the optimal oven temperature production range. Therefore, the same temperature and oven production should be compatible with the curing temperature of the self-adhesive paint, and the compatible temperature range is relatively narrow (600±10), the process conditions are relatively high, the process temperature and speed cannot be adjusted arbitrarily, and the bonding performance and other performances will be affected to a certain extent.

[0066] Table 2. Experimental data table of corona resistance and adhesion performance

Claims

1. A corona-resistant variable frequency self-adhesive wire, characterized in that: It includes a copper conductor and a paint film layer coated on the copper conductor and cured under the same temperature and furnace conditions, wherein the paint film layer includes an inner corona-resistant insulating paint layer and an outer self-adhesive layer; The self-adhesive layer is obtained by coating and curing a self-adhesive insulating varnish of a thermally adhesive aromatic polyamide.

2. The corona-resistant variable frequency self-adhesive wire according to claim 1, characterized in that: The heat-bonding aromatic polyamide self-adhesive insulating varnish comprises, by mass percentage: N-methyl-2-pyrrolidone: 62-64%; Xylene: 1.0-2.0%; Cresol: 0.5-5.0%; Aromatic polyamide resin: 25-27%.

3. The corona-resistant variable frequency self-adhesive wire according to claim 1, characterized in that: The processing hot melting temperature of the heat-bonding aromatic polyamide self-adhesive insulating varnish is 200-240°C.

4. The corona-resistant variable frequency self-adhesive wire according to claim 1, characterized in that: The corona-resistant insulating paint layer is a two-layer insulating layer, wherein the inner layer is a 200-grade polyesterimide frequency conversion insulating layer, and the outer layer is a 220-grade polyamideimide frequency conversion insulating layer; Or the corona-resistant insulating paint layer is a 220-grade polyamide-imide frequency conversion insulating layer; Alternatively, the corona-resistant insulating paint layer is a 240-grade aromatic polyimide layer.

5. The corona-resistant variable frequency self-adhesive wire according to claim 4, characterized in that: The polyesterimide frequency conversion insulation layer is obtained by coating and baking a polyesterimide paint, wherein the solid content of the polyesterimide paint is 38%-41%, and the content of the nano-powder shielding particles in the polyesterimide paint is 1%-10%; The polyamide-imide frequency conversion insulating layer is obtained by coating and baking polyamide-imide paint. The solid content of the polyamide-imide paint is 32%-35%, and the content of nanometer powder shielding particles in the polyamide-imide paint is 5%-9%.

6. The corona-resistant variable frequency self-adhesive wire according to claim 5, characterized in that: In the paint film layer, the nano powder shielding particles are silicon dioxide, silicon carbide, TiO2 / Ag hybrid particles and Ag nano particles embedded in TiO2.

7. The corona-resistant variable frequency self-adhesive wire according to claim 4, characterized in that: When the corona-resistant insulating paint layer is a two-layer insulating layer, in the paint film layer, the thickness of the polyesterimide frequency conversion insulating layer accounts for 30%-40%, the thickness of the polyesterimide frequency conversion insulating layer accounts for 25%-35%, and the self-adhesive layer accounts for 35%-40% of the paint film layer thickness.

8. A method for preparing a corona-resistant variable frequency self-adhesive wire according to any one of claims 1 to 7, characterized in that: include: Annealing the copper conductor, and coating the annealed copper conductor with a corona-resistant insulating varnish layer and an aromatic polyamide self-adhesive insulating varnish in multiple passes; After each coating, the corona-resistant insulating paint layer and the aromatic polyamide self-adhesive insulating paint are cured at the same temperature and in the same furnace to obtain a paint film layer. During the curing process, the temperature of the curing zone is 530° C.-580° C.; The paint film layer is oiled and the wire is wound to obtain a corona-resistant variable frequency self-adhesive wire.

9. The method for preparing the corona-resistant variable frequency self-adhesive wire according to claim 8, characterized in that: During the curing process, the oven inlet temperature is 200℃-350℃, the temperature before catalysis is 600℃~650℃, and the temperature after catalysis is 650℃~700℃.

10. The method for preparing the corona-resistant variable frequency self-adhesive wire according to claim 8, characterized in that: The speed DV is 100-110. When coating the corona-resistant insulating paint layer, the thickness of the paint mold is increased by 0.005-0.007 mm between passes. When coating the aromatic polyamide self-adhesive insulating paint, the thickness of the paint mold is increased by 0.010-0.012 mm between passes.

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