High-aging-resistance wire enamel, enameled stranded wire and preparation method of enameled stranded wire

Abstract

The invention relates to the technical field of enameled wires, in particular to high-aging-resistance wire enamel, an enameled stranded wire and a preparation method of the enameled wire enamel. The preparation method of the high-aging-resistance wire enamel comprises the following steps: firstly, preparing an isocyanate group-terminated polyurethane prepolymer, then preparing epoxy group-modified nano titanium dioxide, and finally, carrying out cross-linking reaction on the polyurethane prepolymer, the modified nano titanium dioxide, amino polysiloxane and polyamine, thereby obtaining the high-aging-resistance wire enamel. According to the wire enamel obtained by the method, when the wire enamel is cured, polysiloxane tends to be enriched on the surface, so that the hydrophobic property is good, the bonding strength of polysiloxane and polyurethane is high, and the heat resistance, the aging resistance and the mechanical property are excellent. The surface of a metal wire core is coated with the wire enamel to prepare an enameled stranded wire, and the enameled stranded wire also has good heat resistance, aging resistance and mechanical property.

Description

Technical Field

[0001] This application relates to the technical field of enameled wires, and particularly relates to a highly aging-resistant enameled wire paint, an enameled stranded wire, and a preparation method thereof. Background Art

[0002] An enameled wire is a conductive material made by coating a layer of enameled wire paint solution on the surface of a wire core made of copper wire or aluminum wire through processes such as baking. It is a core component of motors, electrical appliances, and electronic equipment. The performance of the enameled wire directly determines the reliability and safety of the equipment operation. With the development of industrial technology towards high power and miniaturization, higher requirements are put forward for the heat resistance and aging resistance of enameled wires in equipment such as motors and transformers. However, under the action of long-term high temperature, electric field, and harsh environmental factors, enameled wires generally have aging problems such as a decrease in insulation performance and a weakening of mechanical strength, resulting in an increase in equipment failure rate and maintenance cost.

[0003] As a part of the enameled wire, the enameled wire paint has a very important impact on the aging resistance of the enameled wire. Currently, the more commonly used enameled wire paints include polyester-based, polyurethane-based, polyamide-based, and polyimide-based. Among them, the polyimide-based enameled wire paint has very good aging resistance and a very high heat resistance grade, but it has a high cost and a complex process; while the polyester-based, polyurethane-based, and polyamide-based enameled wire paints all have problems of poor aging resistance.

[0004] The above-mentioned polyurethane-based enameled wire paint has strong adhesion, high-frequency resistance, good corrosion resistance, and has direct soldering properties. In order to improve its aging resistance, the method of composite coating is often used. For example, the patent application document with the publication number of CN106519649A discloses an aging-resistant insulated enameled wire, which includes a metal wire core and an insulating layer wrapped around the outer layer of the metal wire core. The insulating layer is composed of a polyurethane insulating layer attached to the surface of the metal wire core and an insulating paint layer coated on the outer surface of the polyurethane insulating layer. The polyurethane insulating layer is made of polyether polyol, toluene diisocyanate, epoxy resin, propylene glycol, and modified filler, and the insulating paint layer is made of epoxy-modified silicone resin, acrylic resin, pigment, modified filler, and dispersant. By sequentially wrapping the polyurethane insulating layer and the insulating paint layer on the surface of the metal wire core, the aging resistance, wear resistance, and corrosion resistance of the enameled wire are improved. However, using this method of composite coating not only has a complex coating process and high cost, but also the bonding strength between the two layers may be poor, which will also affect the aging resistance of the enameled wire. Summary of the Invention

[0005] In order to improve the aging resistance of polyurethane enameled wire paint, this application provides a highly aging-resistant enameled wire paint, an enameled stranded wire, and a preparation method thereof.

[0006] An enameled stranded wire is made by stranding enameled wires. The enameled wire includes a metal wire core and an enamel film coated on the metal wire core. The enamel film is formed by curing a high anti-aging enameled wire paint. The preparation method of the high anti-aging enameled wire paint includes the following steps: S1: React a diol and a diisocyanate under nitrogen protection to obtain a polyurethane prepolymer; S2: Disperse nano-titanium dioxide in DMF, add epoxy group silane and react to obtain modified nano-titanium dioxide; S3: Mix the polyurethane prepolymer and the modified nano-titanium dioxide, add amino polysiloxane, react at room temperature, then raise the temperature to 55-70 °C, add polyamine, and continue to react to obtain.

[0007] In the above technical solution, the polyurethane prepolymer contains a relatively large amount of isocyanate groups, and the surface of the modified nano-titanium dioxide contains epoxy groups. React the polyurethane prepolymer and the modified nano-titanium dioxide with amino polysiloxane. The isocyanate groups in the polyurethane prepolymer react with the amino groups of the amino polysiloxane to introduce polysiloxane into the polyurethane. Since the surface tensions of polysiloxane and polyurethane are different, the surface tension of the polysiloxane chain segment is smaller and tends to enrich on the surface, while the surface tension of the polyurethane is larger and tends to form a stronger force with the surface of the substrate. Therefore, the surface of the formed enamel film shows excellent hydrophobicity, heat resistance, weather resistance and insulation due to the enrichment of more polysiloxane chain segments, and the bottom of the formed enamel film shows good adhesion due to the enrichment of more polyurethane chain segments.

[0008] Moreover, the amino groups of the amino polysiloxane not only react with the isocyanate groups, but also react with the epoxy groups in the titanium dioxide, thereby introducing polysiloxane chain segments onto the surface of the nano-titanium dioxide; after adding polyamine, the amino groups of the polyamine further react with the isocyanate groups and the epoxy groups on the surface of the nano-titanium dioxide to form an interpenetrating cross-linked network structure, which not only improves the anti-aging performance and heat resistance of the enamel film, but also increases the interaction between polysiloxane and polyurethane, reduces the risk of phase separation caused by poor compatibility between polyurethane chain segments and polysiloxane chain segments, and enhances the strength of the enamel film, thereby further improving the anti-aging performance, heat resistance and mechanical properties of the enamel film.

[0009] In addition, compared with the composite coating, the enamel film formed after coating and curing the enameled wire paint obtained by the above method reduces at least one coating process, the coating process is simpler, and the cost is reduced; moreover, the introduced nano-titanium dioxide is also beneficial to improving the anti-aging performance, heat resistance and mechanical properties of the enamel film.

[0010] Preferably, the enameled stranded wire is a helical stranded body formed by twisting multiple enameled single wires with a certain structure and a specific lay length according to certain rules, such as concentric stranding and bunch stranding. Generally, according to different insulation grades and usage requirements, the diameters of the metal wire cores and the thicknesses of the enameled wire coatings are different.

[0011] Further preferably, the requirements for stranding are as follows: the maximum number of stranding times is 4 times, the maximum number of strands is 7200 strands, the maximum finished outer diameter is 8 mm, and the minimum lay length is 2.2 mm.

[0012] Preferably, in the step S1, the molar ratio of the diol to the diisocyanate is 1:(1.4 - 2).

[0013] By adopting the above technical solution, the prepared polyurethane prepolymer contains more isocyanate groups, which is beneficial to the subsequent reaction with the amino groups in the amino polysiloxane and polyamine, introducing polysiloxane chain segments with better weather resistance, heat resistance and hydrophobicity, and forming a cross-linked network, effectively reducing the phase separation between the polysiloxane chain segments and the polyurethane chain segments.

[0014] In some specific embodiments, in the step S1, the molar ratio of the diol to the diisocyanate can be 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2. Generally, in the step S1, when the molar ratio of the diol to the diisocyanate is 1:1.7, better experimental results can be obtained.

[0015] Preferably, in the step S2, the mass ratio of the nano-titanium dioxide to the epoxy group silane is 1:(0.3 - 0.6).

[0016] In some specific embodiments, in the step S2, the mass ratio of the nano-titanium dioxide to the epoxy group silane can be 1:0.3, 1:0.35, 1:0.4, 1:0.45, 1:0.5, 1:0.55, 1:0.6. Generally, in the step S2, when the mass ratio of the nano-titanium dioxide to the epoxy group silane is 1:0.5, better experimental results can be obtained.

[0017] Preferably, in the step S3, the amino polysiloxane is prepared by reacting an organosiloxane monomer with an amino silane coupling agent, and the mass ratio of the organosiloxane monomer to the amino silane coupling agent is 1:(0.2 - 0.5).

[0018] In the above technical solution, the more the amino silane coupling agent is added, the higher the amino content in the amino polysiloxane, and the more polysiloxane chain segments are introduced into the polyurethane.

[0019] In some specific embodiments, in step S3, the mass ratio of the organosiloxane monomer to the aminosilane coupling agent can be 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.45, 1:0.5. Generally, in step S3, when the mass ratio of the organosiloxane monomer to the aminosilane coupling agent is 1:0.35, better experimental results can be obtained.

[0020] Preferably, the organosiloxane monomer is one or more of diphenyldimethoxysilane, phenyltrimethoxysilane, and phenyltriethoxysilane; and / or, the aminosilane coupling agent is one or more of γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane.

[0021] Preferably, in step S3, the polyamine is one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and p-phenylenediamine.

[0022] By adopting the above technical solution, adding polyamine can form a crosslinked network structure, improve the bonding strength between polyurethane and polysiloxane, reduce phase separation between the two, and thus improve heat resistance, aging resistance, mechanical properties, etc.

[0023] Further preferably, in step S3, a curing agent is added after adding the polyamine. The curing agent is tetrabutyl titanate or dibutyltin oxalate; the mass ratio of the aminopolysiloxane to the curing agent is 100:(1 - 5).

[0024] In the above technical solution, adding a curing agent is beneficial to improving the curing rate of polysiloxane and reducing the curing temperature of polysiloxane, thereby reducing film defects caused by different curing processes of polyurethane and polysiloxane, such as incomplete curing of polysiloxane under polyurethane curing conditions or stress concentration inside polyurethane under polysiloxane curing conditions.

[0025] In some specific embodiments, in step S3, the mass ratio of the aminopolysiloxane to the curing agent can be 100:1, 100:2, 100:2.5, 100:3, 100:3.5, 100:4, 100:4.5, 100:5. Generally, in step S3, when the mass ratio of the aminopolysiloxane to the curing agent is 100:3, better experimental results can be obtained.

[0026] Further preferably, in step S3, the mass ratio of the sum of the mass of the polyurethane prepolymer and the modified nano-titanium dioxide to the mass of the aminopolysiloxane is 100:(10 - 30); And / or, in the step S3, the mass ratio of the sum of the mass of the polyurethane prepolymer and the modified nano-titanium dioxide to the mass of the polyamine is 100:(1 - 5).

[0027] Adopting the above technical solution, when the addition amount of the amino polysiloxane is small, the polysiloxane chain segments introduced into the polyurethane are less, so the polysiloxane chain segments enriched on the surface are less, which is not conducive to improving the hydrophobicity, heat resistance, aging resistance, etc. of the paint film; if the addition amount of the amino polysiloxane is too much, the flexibility of the paint film increases, but the hardness is insufficient, which will also affect the mechanical properties and aging resistance of the enameled wire.

[0028] When the addition amount of the polyamine is large, the crosslinking rate is accelerated and the crosslinking degree is increased. On the contrary, if the addition amount of the polyamine is small, the crosslinking rate is slowed down and the crosslinking degree is decreased.

[0029] In some specific embodiments, in the step S3, the mass ratio of the sum of the mass of the polyurethane prepolymer and the modified nano-titanium dioxide to the mass of the amino polysiloxane can be 100:10, 100:12, 100:15, 100:18, 100:20, 100:22, 100:25, 100:28, 100:30. Generally, in the step S3, when the mass ratio of the sum of the mass of the polyurethane prepolymer and the modified nano-titanium dioxide to the mass of the amino polysiloxane is 100:18, better experimental results can be obtained.

[0030] In some specific embodiments, in the step S3, the mass ratio of the sum of the mass of the polyurethane prepolymer and the modified nano-titanium dioxide to the mass of the polyamine can be 100:1, 100:1.5, 100:2, 100:2.5, 100:3, 100:3.5, 100:4, 100:4.5, 100:5. Generally, in the step S3, when the mass ratio of the sum of the mass of the polyurethane prepolymer and the modified nano-titanium dioxide to the mass of the polyamine is 100:3, better experimental results can be obtained.

[0031] Preferably, the curing conditions of the high-aging-resistant enameled wire paint are: the furnace temperature is 280 - 380 °C, the softening temperature is 410 - 460 °C, and the wire outlet speed is 115 - 285 m / min.

[0032] In the above technical solution, full-automatic baking of paint is carried out by a full-automatic paint baking machine. First, before starting the machine, clean all guide wheels, the sand guide grooves in front of and behind the guide wheels, and the nip plate of the cord, to keep the guide wheels, sand guide grooves, and nip plate smooth, flexible, and clean. Second, after starting the machine, when the temperature reaches the set temperature, open the exhaust gas switch to carry out early waste discharge. As the vehicle speed gradually increases, the speed of the exhaust fan also gradually increases accordingly. Third, the vehicle speed should not be too fast, otherwise it is easy to produce unqualified products and increase waste wire. If the vehicle speed is too slow, the take-up head cannot drive the spool, affecting normal take-up. Finally, the produced finished products should be handled with care to avoid surface scratches or abrasions, etc.

[0033] A highly aging-resistant enameled wire paint is prepared by the above preparation method.

[0034] In the above technical solution, the enameled wire paint is a polysiloxane-modified polyurethane, and an interpenetrating crosslinked network is formed. At the same time, nano-titanium dioxide is introduced to improve the aging resistance, heat resistance, mechanical properties, hydrophobic properties, etc. of the enameled wire paint.

[0035] Compared with the prior art, the present application has the following beneficial effects: 1. In the present application, polysiloxane is introduced into polyurethane. Since polysiloxane has good heat resistance, weather resistance, and hydrophobicity, and tends to accumulate on the surface, while polyurethane has strong adhesion, the formed enameled wire paint film not only has strong adhesion, but also has good aging resistance, heat resistance, hydrophobic properties, and mechanical properties.

[0036] 2. In the present application, nano-titanium dioxide is modified, and epoxy groups are introduced on the surface of titanium dioxide, which can react with amino polysiloxane and polyamine, and form an interpenetrating crosslinked network with the polyurethane chain. This not only improves the temperature resistance, aging resistance, etc. of polyurethane, but also restricts the microphase separation between polysiloxane chain segments and polyurethane chain segments, improving the strength of the enameled wire paint film, and thus improving the aging resistance, heat resistance, hydrophobic properties, mechanical properties, etc. of the enameled wire paint.

[0037] 3. In the present application, by adding a curing agent, the crosslinking rate of polysiloxane chain segments is increased, enabling polysiloxane to complete curing at a lower temperature, and reducing the performance degradation of the enameled wire paint film caused by poor curing. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is the water contact angle of the enameled wire paint film.

[0039] Figure 2 is the cross-sectional microscopic morphology of the enameled wire paint films of Comparative Example 1 and Example 3.

[0040] Figure 3 is a schematic diagram of enameled wire stranding.

[0041] Figure 4 This is the process flow diagram for the production of enameled stranded wires. Specific implementation manners

[0042] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present application.

[0043] Example 1 The preparation method of the enameled wire paint in this embodiment includes the following steps: S1: Add 50 g of polyoxypropylene glycol (Mn is 1000) to a three-necked flask, then place the three-necked flask in an 80 °C water bath and stir. Add 11.8 g of hexamethylene diisocyanate, introduce nitrogen, and react for 2.5 h to obtain a polyurethane prepolymer; S2: Weigh 10 mL of isopropyl titanate and 100 mL of glacial acetic acid, stir for 15 min, add them to 500 mL of deionized water, stir and react at 75 °C for 0.5 h, raise the temperature to 95 °C and react for 1 h. Dilute the reaction solution 3 times with deionized water and transfer it to a hydrothermal reactor. React at 150 °C for 8 h. After the reaction is completed, cool to room temperature and vacuum dry at 80 °C to obtain a powder. Weigh 10 g of the powder and ultrasonically disperse it in 400 mL of DMF. Add 3 g of β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, disperse evenly and place it in a three-necked flask. React at 75 °C under nitrogen protection for 20 h. After the reaction is completed, precipitate with ethyl acetate to obtain modified nano-titanium dioxide; S3: Weigh 95 g of the polyurethane prepolymer and 5 g of the modified nano-titanium dioxide, mix them evenly, slowly add 10 g of diaminopropyl polydimethylsiloxane, protect with nitrogen, react at room temperature for 1 h, then raise the temperature to 55 °C, add 1 g of p-phenylenediamine, and continue to react for 2 h. Evacuate to remove bubbles, and that's it; The preparation process of the enameled stranded wire in this embodiment is as follows: 1) Paint solution preparation: Mix the enameled wire paint prepared above with phenol, cresol, and xylene, and stir at high speed for 30 min to obtain a paint solution with a solid content of 35%, and set it aside; 2) Preparation before startup: First, use a cotton flannel and a brush to scrub all the guide wheels on the machine, the sand guide grooves and the nip plate splints in front of and behind the guide wheels, all the heads at the headstock, the furnace inlets and outlets, the paint tank, the nip bar shelf and the nip bar pressing blocks above the paint tank, and the paint rollers, etc. Then, scrub them again with a small amount of acetone until they are clean and smooth; install one finished bobbin tube and one waste yarn bobbin tube on each head. Replace the nip bars on time. Then, check and record the spool identification on the wire guiding record sheet. Place the spool below the wire feeding positioning steel ring and align it vertically with the positioning steel ring. Cover it with a brush; 3) Startup: Connect the power supply, set the furnace inlet temperature to 300 °C and the furnace outlet temperature to 360 °C. After the temperature reaches the set temperature, turn on the exhaust gas switch, set the exhaust fan speed to 200 r / min, set the traction speed to 40 m / min, turn on the power supply of the waxing device to make the white wax enter the nip bar in the waxing box, so that the whole nip bar is soaked with white wax; transport the wire spool to the wire feeding area, thread the wire through the felt pressing plate, the wire guiding groove, and the guide wheels, and then reach the annealing furnace inlet. Use a steel wire to thread the wire into the thin tube of the annealing furnace. After the wire exits the annealing furnace, it passes through the wire hook and the guide wheels and enters the oven inlet for splitting the wire back and forth, and is led out of the oven inlet through 8 channels.

[0044] 4) Painting: Let the 0.2 mm copper wire pass through the white wax nip bar, thread it through the wire arranging guide wheels and wind it around the waste yarn bobbin tube of the take-up spool. Turn on the power supply of the spool and start it slowly. After all the wire ends are wound around the take-up spool, turn on the power supply of the paint pump to fill the paint tank with paint liquid; neatly and flatly place the dry nip bars and the painted nip bars on the nip bar shelf and press them with a nip bar pressing plate that conforms to the wire gauge. Turn on all the take-up spools, slowly increase the vehicle speed to 60 m / min, turn on the paint cylinder to paint the copper wire, and slowly increase the vehicle speed to 120 m / min. Use a laser diameter gauge to measure the diameter, record the outer diameter of each spool, which is 0.27 ± 0.01 mm, and that's all right.

[0045] Example 2 The preparation method of the enameled wire paint in this example includes the following steps: S1: Add 50 g of polytetrahydrofuran ether diol (Mn is 1000) to a three-necked flask, then place the three-necked flask in an 80 °C water bath and stir. Add 17.4 g of toluene-2,4-diisocyanate, introduce nitrogen gas, and react for 2.5 h to obtain a polyurethane prepolymer; S2: Weigh 10 mL of isopropyl titanate and 100 mL of glacial acetic acid, stir for 15 min, add them to 500 mL of deionized water, stir and react at 75 °C for 0.5 h, raise the temperature to 95 °C and react for 1 h. Dilute the reaction solution 3 times with deionized water and then transfer it to a hydrothermal reactor, react at 150 °C for 8 h. After the reaction is completed, cool to room temperature and vacuum dry at 80 °C to obtain a powder. Weigh 10 g of the powder, ultrasonically disperse it in 400 mL of DMF, add 6 g of γ-glycidoxypropyltrimethoxysilane, and after uniform dispersion, place it in a three-necked flask and react under nitrogen protection at 75 °C for 20 h. After the reaction is completed, precipitate with ethyl acetate to obtain modified nano-titanium dioxide; S3: Weigh 95 g of polyurethane prepolymer and 5 g of modified nano-titanium dioxide, mix them thoroughly, slowly add 30 g of amino polysiloxane, protect with nitrogen, react at room temperature for 1 h, then raise the temperature to 70 °C, add 5 g of diethylenetriamine, and continue to react for 1 h. Then evacuate to remove bubbles, and that's it; The preparation method of the amino polysiloxane in this example includes the following steps: Weigh 20 g of phenyltrimethoxysilane and 4 g of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, place them in a three-necked flask, add an aqueous hydrochloric acid solution with a mass fraction of 1%, react at room temperature for 15 min, then raise the temperature to 80 °C and react for 6 h, and then carry out rotary evaporation and separation; The preparation process of the enameled stranded wire in this example is the same as that in Example 1.

[0046] Example 3 The preparation method of the enamel paint in this example includes the following steps: S1: Add 50 g of poly(adipic acid-1,4-butanediol) diol (Mn is 1000) to a three-necked flask, then place the three-necked flask in an 80 °C water bath and stir, add 21.3 g of diphenylmethane diisocyanate, introduce nitrogen, and react for 2.5 h to obtain a polyurethane prepolymer; S2: Weigh 10 mL of isopropyl titanate and 100 mL of glacial acetic acid, stir for 15 min, add them to 500 mL of deionized water, stir and react at 75 °C for 0.5 h, raise the temperature to 95 °C and react for 1 h. Dilute the reaction solution 3 times with deionized water and then transfer it to a hydrothermal reactor, react at 150 °C for 8 h. After the reaction is completed, cool to room temperature and vacuum dry at 80 °C to obtain a powder. Weigh 10 g of the powder, ultrasonically disperse it in 400 mL of DMF, add 5 g of γ-glycidoxypropyltrimethoxysilane, and after uniform dispersion, place it in a three-necked flask and react under nitrogen protection at 75 °C for 20 h. After the reaction is completed, precipitate with ethyl acetate to obtain modified nano-titanium dioxide; S3: Weigh 95 g of polyurethane prepolymer and 5 g of modified nano-titanium dioxide, mix them thoroughly, then slowly add 18 g of amino-polysiloxane, protect with nitrogen, react at room temperature for 1 h, then raise the temperature to 60 °C, add 3 g of tetraethylenepentamine, continue to react for 1 h, add 0.54 g of tetrabutyl titanate, mix well and then evacuate to remove bubbles, and that's it. The preparation method of the amino-polysiloxane in this example includes the following steps: Weigh 20 g of diphenyldimethoxysilane and 7 g of γ-aminopropyltriethoxysilane, place them in a three-necked flask, add an aqueous hydrochloric acid solution with a mass fraction of 1%, react at room temperature for 15 min, then raise the temperature to 80 °C and react for 6 h, and then carry out rotary evaporation and separation. The preparation process of the enameled stranded wire in this example is the same as that in Example 1.

[0047] Comparative Example 1 The preparation method of the enamel paint in this comparative example includes the following steps: S1: Add 50 g of polyoxypropylene glycol (Mn is 1000) to a three-necked flask, then place the three-necked flask in an 80 °C water bath and stir, add 11.8 g of hexamethylene diisocyanate, introduce nitrogen, and react for 2.5 h to obtain a polyurethane prepolymer. S2: Weigh 95 g of polyurethane prepolymer and 5 g of nano-silica, slowly add 10 g of diaminopropyl polydimethylsiloxane, protect with nitrogen, react at room temperature for 1 h, then raise the temperature to 60 °C, add 1 g of p-phenylenediamine, continue to react for 1 h, evacuate to remove bubbles, and that's it. The preparation process of the enameled stranded wire in this comparative example is the same as that in Example 1.

[0048] Performance testing Preparation of enamel paint film Mix the enamel paints of Examples 1 - 3 and Comparative Example 1 with phenol, cresol, and xylene, stir at high speed for 30 min to obtain a paint solution with a solid content of 35%, then spread it on a polytetrafluoroethylene plate, naturally dry at room temperature for 24 h, then put it into a blast drying oven and dry at 65 °C for 6 h, and then put it into a vacuum drying oven and dry at 65 °C for 6 h, cut it into dumbbell-shaped standard specimens with a length of 40 mm and a width of 10 mm for standby, measure the film thickness to be 0.3 ± 0.1 mm.

[0049] 1. Mechanical property testing Test method: Use a bench-top electronic precision universal testing machine to measure the tensile strength and elongation at break of the standard specimens, conduct a tensile test with a 500 N sensor, the tensile rate is 100 mm / min, and take the average value of 3 tensile specimens as the test result.

[0050] ① Thermal aging test: Cut the standard sample strips and place them in a muffle furnace. After heating to 180 °C, keep them at this temperature for 12 h, then take samples to test the tensile strength and elongation at break.

[0051] ② High temperature and high humidity test: Put the cut standard sample strips into a thermo-hygrostat chamber with a temperature of 85 ± 2 °C and a humidity of 95 ± 5%. Place them for 7 days. After taking them out, dry the sample strips, then vacuum dry them at 60 °C for 24 h, and then conduct tensile property tests.

[0052] At the same time, conduct a blank test, that is, test the mechanical properties when no aging test is carried out. The results are shown in Table 1.

[0053] Table 1 Test results of the mechanical properties of the enameled wire coatings in Examples 1 - 3 and Comparative Example 1 2. Water contact angle test Place the newly prepared enameled wire coating on a contact angle tester, drop 300 μL of water each time, and measure the contact angle of water on the coating. The results are as Figure 1 shown.

[0054] 3. Scanning electron microscopy observation Use scanning electron microscopy to observe the cross-section of the enameled wire coatings in Example 3 and Comparative Example 1. The microscopic morphology is as Figure 2 shown.

[0055] 4. Thermal property test Refer to the standard GB / T 4074.6 - 2008, and use a softening breakdown tester to conduct softening breakdown tests on the enameled wires. The test conditions are 220 °C, 4.5 N, and 2 min; use a hot air drying oven to conduct thermal shock tests on the enameled wires. The oven temperature is 200 °C, and the thermal shock time is 30 min. Use a magnifying glass to observe the cracking situation on the surface of the coating. It is found that no cracking phenomenon occurs on the enameled wires in Examples 1 - 3, and the temperature grade meets Class 155, while cracks appear on the surface of the enameled wire in Comparative Example 1.

[0056] Result analysis As can be seen from Table 1, after thermal aging or high temperature and high humidity treatment, the tensile strength and elongation at break of the enameled wire coating in Comparative Example 1 have decreased significantly, indicating poor aging resistance, while the enameled wire coatings in the examples have good aging resistance.

[0057] From Figure 1 it can be seen that the hydrophobic properties of the enameled wire coatings in Examples 1 - 3 and the comparative example are good, probably because the polysiloxane chain segments tend to enrich on the surface during the curing process of the enameled wire paint.

[0058] From Figure 2It can be seen that there is a relatively serious phase separation phenomenon in the enameled wire film of the comparative example, while the phase separation phenomenon of the enameled wire film of Example 3 is weakened. Combining with the mechanical property analysis, it can be known that the polyurethane and polysiloxane in Example 3 have a strong binding strength.

[0059] Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present invention.

Claims

1. An enameled stranded wire, characterized in that, It is made by stranding enameled wires. The enameled wires include a metal wire core and an enamel film coated outside the metal wire core. The enamel film is formed by curing a highly aging-resistant enameled wire paint. The preparation method of the highly aging-resistant enameled wire paint includes the following steps: S1: React diol and diisocyanate under nitrogen protection to obtain a polyurethane prepolymer; S2: Disperse nano-titanium dioxide in DMF, add epoxy group silane and react to obtain modified nano-titanium dioxide; S3: Mix the polyurethane prepolymer and the modified nano-titanium dioxide evenly, add amino polysiloxane, react at room temperature, then heat up to 55 - 70 °C, add polyamine, and continue to react to obtain the product.

2. The enameled stranded wire according to claim 1, wherein In the step S1, the molar ratio of diol to diisocyanate is 1:(1.4 - 2).

3. The enameled stranded wire according to claim 1, wherein, In the step S2, the mass ratio of nano-titanium dioxide to epoxy group silane is 1:(0.3 - 0.6).

4. The enameled stranded wire according to claim 1, wherein, In the step S3, the amino polysiloxane is prepared by reacting an organosiloxane monomer with an amino silane coupling agent, and the mass ratio of the organosiloxane monomer to the amino silane coupling agent is 1:(0.2 - 0.5).

5. The enameled stranded wire according to claim 4, characterized in that, The organosiloxane monomer is one or more of diphenyl dimethoxysilane, phenyl trimethoxysilane, and phenyl triethoxysilane; And / or, the amino silane coupling agent is one or more of γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane.

6. The enameled stranded wire according to claim 1, wherein In the step S3, the polyamine is one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and p-phenylenediamine.

7. The enameled stranded wire according to claim 1, wherein In the step S3, a curing agent is added after adding the polyamine, and the curing agent is tetrabutyl titanate or dibutyltin oxalate; And / or, the mass ratio of the amino polysiloxane to the curing agent is 100:(1 - 5).

8. The enameled stranded wire according to claim 1, wherein In the step S3, the mass ratio of the sum of the masses of the polyurethane prepolymer and the modified nano-titanium dioxide to the mass of the amino polysiloxane is 100:(10 - 30); And / or, in the step S3, the mass ratio of the sum of the masses of the polyurethane prepolymer and the modified nano-titanium dioxide to the mass of the polyamine is 100:(1 - 5).

9. The enameled stranded wire according to claim 1, wherein The conditions for curing the highly aging-resistant enameled wire paint are: the furnace temperature is 280 - 380 °C, the softening temperature is 410 - 460 °C, and the wire outlet speed is 115 - 285 m / min.

10. A highly anti-aging enameled wire paint, characterized in that, It is prepared by adopting the following preparation method: S1: React diol and diisocyanate under nitrogen protection to obtain a polyurethane prepolymer; S2: Disperse nano-titanium dioxide in DMF, add epoxy group silane and react to obtain modified nano-titanium dioxide; S3: Mix the polyurethane prepolymer and the modified nano-titanium dioxide evenly, add amino polysiloxane, react at room temperature, then heat up to 55 - 70 °C, add polyamine, and continue to react to obtain the product.

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