Heat-resistant flexible three-layer insulated wire for high-frequency transformer and preparation method of heat-resistant flexible three-layer insulated wire

Abstract

The invention discloses a heat-resistant flexible three-layer insulated wire for a high-frequency transformer and a preparation method of the heat-resistant flexible three-layer insulated wire, and relates to the technical field of three-layer insulated wires. The invention discloses a preparation method of a heat-resistant flexible three-layer insulated wire for a high-frequency transformer, and the method comprises the following steps: sequentially wrapping the outer side of a conductor with a first insulating polymer layer, a second insulating polymer layer and a nylon modified glass fiber outer layer to obtain a three-layer insulated wire; the preparation method of the nylon modified glass fiber outer layer comprises the following steps that a wire with the surface wrapped with a first insulating polymer layer and a second insulating polymer layer penetrates through a die opening of an extruder and is coated with a nylon modified glass fiber material, and the nylon modified glass fiber outer layer is obtained; the prepared three-layer insulated wire has the advantages of being ultrathin, high in flexibility, resistant to breakage, high in insulativity and high in voltage resistance.

Description

Technical Field

[0001] The invention relates to the technical field of three-layer insulated wires, and in particular to a heat-resistant flexible three-layer insulated wire for a high-frequency transformer and a preparation method thereof. Background Art

[0002] Three-layer insulated wire, also known as triple insulated wire, is a new high-performance insulated wire developed internationally in recent years. This wire has three insulation layers and a metal core wire in the middle. With the miniaturization, lightness, and high frequency of various electronic equipment, communication equipment, motors, household appliances, etc., three-layer insulated wire is widely used in cutting-edge technology and defense fields. It is an essential material for manufacturing high-frequency transformer windings for miniaturized switching power supplies. High-frequency switching power supplies are used in almost all electronic equipment and are an indispensable key subsystem for the rapid development of today's electrical industry and electronic information industry. At present, high-frequency switching power supplies are developing in the direction of high forward conversion rate and high control accuracy, and are also becoming lighter and smaller. In order to achieve lightweight and miniaturization of high-frequency switching power supplies, the key is to achieve miniaturization and reliability of internal parts of high-frequency switching power supplies. However, with the high frequency of transformers, the insulation strength of the original insulating wire material, enameled wire, can no longer meet the needs, which has become the primary reason restricting the development of high-frequency transformers. High-frequency transformers assembled with three-layer insulated wires have the same number of wires and cross-sectional area, and the volume becomes smaller, and automated winding production can also be achieved.

[0003] However, the common three-layer insulated wires still have a lot of room for improvement in terms of insulation, flexibility, heat resistance, etc. At present, the insulation layer of three-layer insulated wires generally uses PET, PEN or a mixture of PET and PEN. The material is too hard and easy to break. When used in small electrical components that need to be bent repeatedly, it is easy to cause insulation failure during operation. In addition, it is difficult to combine the three properties of insulation, flexibility, and heat resistance of most insulation layer materials. Summary of the invention

[0004] The purpose of the present invention is to provide a heat-resistant flexible three-layer insulated wire for a high-frequency transformer and a preparation method thereof, so as to solve the following technical problems:

[0005] Existing insulation layer materials are difficult to simultaneously possess high insulation, high flexibility and heat resistance, which affects their application in high-frequency transformers.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for preparing a heat-resistant flexible three-layer insulated wire for a high-frequency transformer, characterized in that it comprises the following steps: sequentially wrapping a first insulating polymer layer, a second insulating polymer layer and a nylon modified glass fiber outer layer on the outer side of a conductor to obtain a three-layer insulated wire;

[0008] The method for preparing the nylon modified glass fiber outer layer comprises the following steps: passing a wire having a first insulating polymer layer and a second insulating polymer layer wrapped on the surface through an extruder die to coat the nylon modified glass fiber material to obtain a nylon modified glass fiber outer layer;

[0009] The nylon modified glass fiber material includes the following raw materials in parts by weight:

[0010] S1: add octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane to a reaction kettle, control the temperature at 40-50°C, evacuate to remove water, then introduce nitrogen to restore to normal pressure, add hexadecylheptasiloxane and tetramethylammonium hydroxide siliconate, control the temperature at 110-120°C, keep the temperature for reaction for 2-4h, control the temperature at 160-165°C, evacuate to remove unreacted small molecules, remove the negative pressure, introduce nitrogen to restore to normal pressure and temperature, and obtain component 1;

[0011] S2: Add component 1 and tetrahydrofuran into a reaction kettle and disperse them evenly, add thiolated glass fiber and benzoin dimethyl ether, treat with ultraviolet light for 0.5-1h, add anhydrous ethanol for washing, and dry to obtain component 2;

[0012] S3: Add component 2 and chlorobenzene into the reaction kettle, control the temperature at 55-60°C, disperse evenly, add m-chloroperbenzoic acid, keep the reaction for 36-72 hours, control the temperature at -10~-5°C, keep the reaction for 12-15 hours, filter, wash with methanol, and obtain elastomer-modified glass fiber;

[0013] S4: PA66 and elastomer-modified glass fiber are mixed and added into a twin-screw extruder, extruded into granules, and dried to obtain nylon-modified glass fiber material.

[0014] As a further solution of the present invention: the addition ratio of octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane, hexadecylheptasiloxane and tetramethylammonium hydroxide siliconate in S1 is 10g: 1.5-5g: 0.005-0.01g: 0.1-0.2g.

[0015] As a further solution of the present invention: the addition ratio of component 1, tetrahydrofuran, thiolated glass fiber and benzoin dimethyl ether in S2 is 10g: 50-100mL: 2-4g: 0.02-0.03g.

[0016] As a further solution of the present invention: the addition ratio of component 1, chlorobenzene and meta-chloroperbenzoic acid in S3 is 10g:200-400mL:0.5-1g.

[0017] As a further solution of the present invention: the mass ratio of PA66 to elastomer-modified glass fiber in S4 is 10:1-4.

[0018] As a further solution of the present invention: the preparation method of mercaptolated glass fiber comprises the following steps: adding high-temperature calcined glass fiber, γ-mercaptopropyltrimethoxysilane and deionized water into a reaction kettle for blending, controlling the temperature at 50-60°C, heat preservation for 2-4 hours, washing with water and drying to obtain mercaptolated glass fiber.

[0019] As a further solution of the present invention: the preparation method of high-temperature calcined glass fiber comprises the following steps: calcining the glass fiber at 350-400°C for 6s to remove the original impregnating agent on the fiber surface to obtain the high-temperature calcined glass fiber.

[0020] As a further solution of the present invention: the addition ratio of the glass fiber after high temperature calcination, γ-mercaptopropyltrimethoxysilane and deionized water is 10g: 0.5-1g: 50-100mL.

[0021] As a further scheme of the present invention: the preparation method of tetramethylammonium hydroxide siliconate comprises the following steps: adding 20g of octamethylcyclotetrasiloxane and 0.8g of 25wt% tetramethylammonium hydroxide aqueous solution into a reaction bottle and dispersing them evenly, controlling the temperature at 40-50°C, vacuuming and removing water, introducing nitrogen to restore normal pressure, controlling the temperature at 75-85°C, and keeping the temperature for reaction for 2-4h to obtain tetramethylammonium hydroxide siliconate.

[0022] As a further embodiment of the present invention: the mixing temperature of the twin-screw extruder is 250-270°C.

[0023] As a further solution of the present invention: the preparation method of the first insulating polymer layer comprises the following steps: wrapping a polyimide film on the surface of the wire to obtain the first insulating polymer layer.

[0024] As a further scheme of the present invention: the preparation method of the second insulating polymer layer comprises the following steps: passing a wire with a first insulating polymer layer wrapped on its surface through an extruder die to coat a second insulating polymer material to obtain a second insulating polymer layer; the second insulating polymer material comprises the following raw materials in parts by weight: 15-35 parts of polytrimethylene terephthalate, 50-70 parts of polyethylene terephthalate, 5-10 parts of polybutylene terephthalate, 1-3 parts of a compatibilizer, and 1-2 parts of a masterbatch; the compatibilizer is maleic anhydride modified polyethylene.

[0025] As a further solution of the present invention: the thickness of the first insulating polymer layer is 0.01-0.02mm; the thickness of the second insulating polymer layer is 0.02-0.05mm; the thickness of the nylon modified glass fiber outer layer is 0.08-0.15mm; the total thickness of the first insulating polymer layer, the second insulating polymer layer and the nylon modified glass fiber outer layer is 0.08-0.2mm.

[0026] As a further solution of the present invention: the conductor is a copper core wire after annealing, and the diameter of the copper core wire is 0.2-1 mm.

[0027] A heat-resistant flexible three-layer insulated wire for a high-frequency transformer is made by any one of the above-mentioned preparation methods.

[0028] Beneficial effects of the present invention:

[0029] The present application first uses octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane as raw materials, hexadecylheptasiloxane as a capping agent, and tetramethylammonium hydroxide silicon alkoxide as a catalyst to prepare silicone rubber with vinyl side chains through reaction, that is, component one; and uses γ-mercaptopropyltrimethoxysilane to organically treat the glass fiber to obtain a modified glass fiber with a large number of mercapto groups grafted on the surface, that is, mercaptolated glass fiber; the present application uses the mercapto group of the mercaptolated glass fiber to click with part of the vinyl groups on a side chain of the component, and crosslinks the glass fiber and the silicone rubber through the molecular chain to obtain component two; the present application uses meta-chloroperbenzoic acid to epoxidize the remaining vinyl groups in component two to obtain an elastomer-modified glass fiber. The present application then uses the elastomer-modified glass fiber and PA66 to blend and extrude through a twin-screw extruder, and the epoxy group of the elastomer-modified glass fiber reacts with the terminal amino group and the terminal carboxyl group of PA66, thereby crosslinking the elastomer with PA66 to obtain a nylon-modified glass fiber material.

[0030] After the glass fiber is organically modified, the present application not only improves the dispersion of the glass fiber in the matrix resin, but also improves the interface bonding between the glass fiber and the organic resin through the reaction between the molecular bonds. With the addition of the glass fiber of the present application, the molecular chain on the surface of the glass fiber is cross-linked with the organic silicon molecular chain prepared by component 1 and polyamide 66, and is evenly distributed in the resin matrix, and the thermal stability and mechanical properties of the material are effectively improved. The siloxy groups in the nylon modified glass fiber material prepared by the present application can improve the heat resistance and mechanical properties of the polyamide material; the bond length of the S iOS i bond is long, the molecular gap is large, and the force between the chain segments is low. The present application utilizes the excellent volume thermal expansion coefficient and good temperature stability of the silicone rubber molecular chain and the molecular chain on the surface of the glass fiber, and complements the performance of polyamide 66, which can improve the high and low temperature resistance, hydrophobicity and unstable toughness of polyamide 66, and give the material excellent temperature resistance, mechanical properties and waterproof insulation properties. DETAILED DESCRIPTION

[0031] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Example 1 The preparation method of tetramethylammonium hydroxide siliconate comprises the following steps: adding 20g of octamethylcyclotetrasiloxane and 0.8g of a 25wt% tetramethylammonium hydroxide aqueous solution into a reaction bottle and dispersing them evenly, controlling the temperature at 50°C, evacuating to -0.09MPa to remove water for 1h, introducing nitrogen to restore normal pressure, controlling the temperature at 81°C, and keeping the temperature for reaction for 3h to obtain tetramethylammonium hydroxide siliconate.

[0033] The preparation method of mercaptolated glass fiber comprises the following steps:

[0034] A1: 10um diameter and 3mm length alkali-free chopped glass fiber is placed at 400℃ for 6s to obtain high temperature calcined glass fiber;

[0035] A2: Add 10g of high-temperature calcined glass fiber, 1g of γ-mercaptopropyltrimethoxysilane and 100mL of deionized water into a reactor and mix them. Control the temperature at 60°C, keep the mixture warm for 3h, wash with water and dry to obtain mercaptolated glass fiber.

[0036] The preparation method of maleic anhydride modified polyethylene comprises the following steps: adding 94.5g PP, 6g maleic anhydride, 0.3g initiator diisopropylbenzene peroxide, and 0.2g antioxidant 1010 into a twin-screw extruder for extrusion at an extrusion temperature of 180°C and a rotation speed of 150rpm, and granulating to obtain maleic anhydride modified polyethylene.

[0037] Example 2 The nylon modified glass fiber material includes the following raw materials in parts by weight:

[0038] A1: 10 g of octamethylcyclotetrasiloxane and 5 g of tetramethyltetravinylcyclotetrasiloxane were added to a reaction kettle, the temperature was controlled at 50°C, and the reaction was evacuated to -0.09 MPa for 1 h to remove water, nitrogen was introduced to restore normal pressure, 0.06 g of hexadecylheptasiloxane and 0.1 g of tetramethylammonium hydroxide silicon alkoxide prepared in Example 1 were added, the temperature was controlled at 110°C, and the reaction was kept warm for 3 h, the temperature was controlled at 165°C, the reaction was evacuated to -0.09 MPa for 1 h to remove unreacted small molecules, the negative pressure was removed, nitrogen was introduced to restore normal pressure and temperature, and component 1 was obtained;

[0039] A2: 10 g of component 1 and 50 mL of tetrahydrofuran were added to a reaction kettle and dispersed evenly, 3 g of the thiolated glass fiber prepared in Example 1 and 0.02 g of dimethyl benzoate were added, and the mixture was treated with ultraviolet light for 0.5 h. Anhydrous ethanol was added for washing and drying to obtain component 2;

[0040] A3: Add 10g of component 2 and 200mL of chlorobenzene into the reactor, control the temperature at 55°C, disperse evenly, add 0.5g of m-chloroperbenzoic acid, keep the reaction for 36h, control the temperature at -10°C, keep the reaction for 12h, filter, wash with methanol, and obtain elastomer-modified glass fiber;

[0041] A4: 10g PA66 and 3g elastomer-modified glass fiber were mixed and added into a twin-screw extruder at a mixing temperature of 260°C. The mixture was extruded into granules and dried to obtain nylon-modified glass fiber material.

[0042] Example 3 The nylon modified glass fiber material includes the following raw materials in parts by weight:

[0043] A1: 10 g of octamethylcyclotetrasiloxane and 5 g of tetramethyltetravinylcyclotetrasiloxane were added to a reaction kettle, the temperature was controlled at 50°C, and the reaction was evacuated to -0.09 MPa for 1 h to remove water, nitrogen was introduced to restore normal pressure, 0.06 g of hexadecylheptasiloxane and 0.1 g of tetramethylammonium hydroxide silicon alkoxide prepared in Example 1 were added, the temperature was controlled at 110°C, and the reaction was kept warm for 3 h, the temperature was controlled at 165°C, the reaction was evacuated to -0.09 MPa for 1 h to remove unreacted small molecules, the negative pressure was removed, nitrogen was introduced to restore normal pressure and temperature, and component 1 was obtained;

[0044] A2: 10 g of component 1 and 70 mL of tetrahydrofuran were added to a reaction kettle and dispersed evenly, 3 g of the thiolated glass fiber prepared in Example 1 and 0.02 g of dimethyl benzoate were added, and the mixture was treated with ultraviolet light for 1 h. Anhydrous ethanol was added for washing and drying to obtain component 2;

[0045] A3: Add 10g of component 2 and 300mL of chlorobenzene into the reactor, control the temperature at 60℃, disperse evenly, add 0.5g of m-chloroperbenzoic acid, keep the reaction for 48h, control the temperature at -10℃, keep the reaction for 12h, filter, wash with methanol, and obtain elastomer-modified glass fiber;

[0046] A4: 10g PA66 and 3g elastomer-modified glass fiber were mixed and added into a twin-screw extruder at a mixing temperature of 260°C. The mixture was extruded into granules and dried to obtain nylon-modified glass fiber material.

[0047] Example 4 The nylon modified glass fiber material includes the following raw materials in parts by weight:

[0048] A1: 10 g of octamethylcyclotetrasiloxane and 5 g of tetramethyltetravinylcyclotetrasiloxane were added to a reaction kettle, the temperature was controlled at 50°C, and the reaction was evacuated to -0.09 MPa for 1 h to remove water, nitrogen was introduced to restore normal pressure, 0.06 g of hexadecylheptasiloxane and 0.1 g of tetramethylammonium hydroxide silicon alkoxide prepared in Example 1 were added, the temperature was controlled at 110°C, and the reaction was kept warm for 3 h, the temperature was controlled at 165°C, the reaction was evacuated to -0.09 MPa for 1 h to remove unreacted small molecules, the negative pressure was removed, nitrogen was introduced to restore normal pressure and temperature, and component 1 was obtained;

[0049] A2: 10 g of component 1 and 100 mL of tetrahydrofuran were added to a reaction kettle and dispersed evenly, 3 g of the thiolated glass fiber prepared in Example 1 and 0.03 g of benzoin dimethyl ether were added, and the mixture was treated with ultraviolet light for 1 h, and anhydrous ethanol was added for washing and drying to obtain component 2;

[0050] A3: Add 10g of component 2 and 400mL of chlorobenzene into the reactor, control the temperature at 60℃, disperse evenly, add 1g of m-chloroperbenzoic acid, keep the reaction for 72h, control the temperature at -10℃, keep the reaction for 15h, filter, wash with methanol, and obtain elastomer-modified glass fiber;

[0051] A4: 10g PA66 and 3g elastomer-modified glass fiber were mixed and added into a twin-screw extruder at a mixing temperature of 260°C. The mixture was extruded into granules and dried to obtain nylon-modified glass fiber material.

[0052] Embodiment 5 A method for preparing a heat-resistant flexible three-layer insulated wire for a high-frequency transformer comprises the following steps:

[0053] B1: The outer surface of the annealed copper core wire (diameter 0.2 mm) is wrapped with a polyimide film (thickness 1.2 μm, purchased from the American DuPont company, model 120TWT561 polyimide film) to obtain a first insulating polymer layer, the thickness of the first insulating polymer layer is 0.02 mm;

[0054] B2: 30g of polytrimethylene terephthalate (PTT), 55g of polyethylene terephthalate (PET), 5g of polybutylene terephthalate (PBT), 2g of maleic anhydride-modified polyethylene prepared in Example 1, and 1g of masterbatch are blended to obtain a second layer of insulating polymer material; a wire having a surface coated with the first layer of insulating polymer layer is passed through an extruder die to be coated with a second layer of insulating polymer material to obtain a second layer of insulating polymer layer, the thickness of the second layer of insulating polymer layer is 0.05mm;

[0055] B3: Pass the wire having the first insulating polymer layer and the second insulating polymer layer through the extruder die to be coated with the nylon modified glass fiber material prepared in Example 2 to obtain a three-layer insulated wire having a nylon modified glass fiber outer layer, the thickness of the nylon modified glass fiber outer layer being 0.1 mm.

[0056] Compared with Example 5, Example 6 is the case in which only the nylon modified glass fiber material prepared in Example 2 used in Example 5 is replaced by an equal amount of the nylon modified glass fiber material prepared in Example 3, and the remaining components and preparation methods are completely consistent with those in Example 5.

[0057] Compared with Example 5, Example 7 is that only the nylon modified glass fiber material prepared in Example 2 used in Example 5 is replaced by the nylon modified glass fiber material prepared in Example 4 in equal amount, and the other components and preparation method are exactly the same as those in Example 5.

[0058] Comparative Example 1 The nylon modified glass fiber material includes the following raw materials in parts by weight:

[0059] A1: 10 g of octamethylcyclotetrasiloxane and 5 g of tetramethyltetravinylcyclotetrasiloxane were added to a reaction kettle, the temperature was controlled at 50°C, and the reaction was evacuated to -0.09 MPa for 1 h to remove water, nitrogen was introduced to restore normal pressure, 0.06 g of hexadecylheptasiloxane and 0.1 g of tetramethylammonium hydroxide silicon alkoxide prepared in Example 1 were added, the temperature was controlled at 110°C, and the reaction was kept warm for 3 h, the temperature was controlled at 165°C, the reaction was evacuated to -0.09 MPa for 1 h to remove unreacted small molecules, the negative pressure was removed, nitrogen was introduced to restore normal pressure and temperature, and component 1 was obtained;

[0060] A2: 10 g of component 1 and 70 mL of tetrahydrofuran were added to a reaction kettle and dispersed evenly, 3 g of the thiolated glass fiber prepared in Example 1 and 0.02 g of benzoin dimethyl ether were added, and the mixture was treated with ultraviolet light for 1 h, and anhydrous ethanol was added for washing and drying to obtain an elastomer-modified glass fiber;

[0061] A3: 10g PA66 and 3g elastomer modified glass fiber were mixed and added into a twin-screw extruder at a mixing temperature of 260°C. The mixture was extruded into granules and dried to obtain nylon modified glass fiber material.

[0062] Comparative Example 2 The nylon modified glass fiber material includes the following raw materials in parts by weight:

[0063] A1: 10 g of octamethylcyclotetrasiloxane and 5 g of tetramethyltetravinylcyclotetrasiloxane were added to a reaction kettle, the temperature was controlled at 50°C, and the reaction was evacuated to -0.09 MPa for 1 h to remove water, nitrogen was introduced to restore normal pressure, 0.06 g of hexadecylheptasiloxane and 0.1 g of tetramethylammonium hydroxide silicon alkoxide prepared in Example 1 were added, the temperature was controlled at 110°C, and the reaction was kept warm for 3 h, the temperature was controlled at 165°C, the reaction was evacuated to -0.09 MPa for 1 h to remove unreacted small molecules, the negative pressure was removed, nitrogen was introduced to restore normal pressure and temperature, and component 1 was obtained;

[0064] A2: Add 10g of component 1 and 300mL of chlorobenzene into a reactor, control the temperature at 60°C, disperse evenly, add 0.5g of m-chloroperbenzoic acid, keep the reaction for 48h, control the temperature at -10°C, keep the reaction for 12h, filter, and wash with methanol to obtain a modified elastomer;

[0065] A3: 10 g PA66, 3 g modified elastomer and 0.9 g glass fiber prepared in Example 1 after high temperature calcination were mixed and added into a twin-screw extruder at a mixing temperature of 260° C. The mixture was extruded into granules and dried to obtain a nylon modified glass fiber material.

[0066] Comparative Example 3 The nylon modified glass fiber material includes the following raw materials in parts by weight:

[0067] A1: 10 g of octamethylcyclotetrasiloxane and 5 g of tetramethyltetravinylcyclotetrasiloxane were added to a reaction kettle, the temperature was controlled at 50°C, and the reaction was evacuated to -0.09 MPa for 1 h to remove water, nitrogen was introduced to restore normal pressure, 0.06 g of hexadecylheptasiloxane and 0.1 g of tetramethylammonium hydroxide silicon alkoxide prepared in Example 1 were added, the temperature was controlled at 110°C, and the reaction was kept warm for 3 h, the temperature was controlled at 165°C, the reaction was evacuated to -0.09 MPa for 1 h to remove unreacted small molecules, the negative pressure was removed, nitrogen was introduced to restore normal pressure and temperature to obtain an elastomer;

[0068] A2: 10 g PA66, 3 g elastomer, and 0.9 g mercapto glass fiber prepared in Example 1 were mixed and added into a twin-screw extruder at a mixing temperature of 260° C. The mixture was extruded into granules and dried to obtain a nylon modified glass fiber material.

[0069] Compared with Example 5, Comparative Example 4 is that only the nylon modified glass fiber material prepared in Example 2 used in Example 5 is replaced by the nylon modified glass fiber material prepared in Comparative Example 1 in equal amount, and the other components and preparation methods are completely consistent with Example 5.

[0070] Compared with Example 5, Comparative Example 5 is that only the nylon modified glass fiber material prepared in Example 2 used in Example 5 is replaced by the nylon modified glass fiber material prepared in Comparative Example 2 in equal amount, and the other components and preparation methods are completely consistent with Example 5.

[0071] Compared with Example 5, Comparative Example 6 is the case in which only the nylon modified glass fiber material prepared in Example 2 used in Example 5 is replaced by an equal amount of the nylon modified glass fiber material prepared in Comparative Example 3, and the remaining components and preparation method are completely consistent with those of Example 5.

[0072] Performance Testing

[0073] (1) Insulation performance: The three-layer insulated wires prepared in Examples 5-7 and Comparative Examples 4-6 were placed in an aging box for accelerated aging treatment. The aging treatment program was set as follows: baking at a temperature of 260° C. for 30 min. The three-layer insulated wires after accelerated aging treatment were energized at a test voltage of 3000 V for 60 seconds to observe whether they were broken down. The test results are shown in Table 1.

[0074] (2) Flexibility: The three-layer insulated wires prepared in Examples 5-7 and Comparative Examples 4-6 were placed in an aging box for accelerated aging treatment. The aging treatment program was set as follows: baking at a temperature of 260°C for 30 min; the three-layer insulated wires after accelerated aging treatment were repeatedly bent 180° for 60 times to observe whether the insulating layer on the surface of the three-layer insulated wires was cracked or fell off. The test results are shown in Table 1;

[0075] Table 1: Statistical table of performance test data of Examples 5-7 and Comparative Examples 4-6

[0076] Insulation properties Flexibility Example 5 Not penetrated No cracking, no falling off Example 6 Not penetrated No cracking, no falling off Example 7 Not penetrated No cracking, no falling off Comparative Example 4 28s Breakdown Cracks, no peeling Comparative Example 5 25s breakdown Cracks, no peeling Comparative Example 6 20s breakdown Cracks, partial peeling

[0077] It can be seen from Table 1 that the three-layer insulated wire prepared in the present application has the advantage of good heat aging resistance, and the insulation performance and flexibility are still maintained well after high temperature treatment.

[0078] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for preparing a heat-resistant flexible three-layer insulated wire for a high-frequency transformer, characterized in that: The method comprises the following steps: sequentially wrapping a first insulating polymer layer, a second insulating polymer layer and a nylon modified glass fiber outer layer on the outer side of a conductor to obtain a three-layer insulated wire; The method for preparing the nylon modified glass fiber outer layer comprises the following steps: passing a conductive wire having a first insulating polymer layer and a second insulating polymer layer wrapped on its surface through an extruder die to be coated with a nylon modified glass fiber material to obtain a nylon modified glass fiber outer layer; The nylon modified glass fiber material comprises the following raw materials in parts by weight: S1: add octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane to a reaction kettle, control the temperature at 40-50°C, evacuate to remove water, then introduce nitrogen to restore to normal pressure, add hexadecylheptasiloxane and tetramethylammonium hydroxide siliconate, control the temperature at 110-120°C, keep the temperature for reaction for 2-4h, control the temperature at 160-165°C, evacuate to remove unreacted small molecules, remove the negative pressure, introduce nitrogen to restore to normal pressure and temperature, and obtain component 1; S2: Add component 1 and tetrahydrofuran into a reaction kettle and disperse them evenly, add thiolated glass fiber and benzoin dimethyl ether, treat with ultraviolet light for 0.5-1h, add anhydrous ethanol for washing, and dry to obtain component 2; S3: Add component 2 and chlorobenzene into the reaction kettle, control the temperature at 55-60°C, disperse evenly, add m-chloroperbenzoic acid, keep the reaction for 36-72 hours, control the temperature at -10~-5°C, keep the reaction for 12-15 hours, filter, wash with methanol, and obtain elastomer-modified glass fiber; S4: PA66 and elastomer-modified glass fiber are mixed and added into a twin-screw extruder, extruded into granules, and dried to obtain nylon-modified glass fiber material.

2. The method for preparing a heat-resistant flexible three-layer insulated wire for a high-frequency transformer according to claim 1, characterized in that: The addition ratio of octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane, hexadecylheptasiloxane and tetramethylammonium hydroxide siliconate in S1 is 10g: 1.5-5g: 0.005-0.01g: 0.1-0.2g.

3. The method for preparing a heat-resistant flexible three-layer insulated wire for a high-frequency transformer according to claim 1, characterized in that: The addition ratio of component 1, tetrahydrofuran, mercaptolated glass fiber, and benzoin dimethyl ether in S2 is 10g: 50-100mL: 2-4g: 0.02-0.03g.

4. The method for preparing a heat-resistant flexible three-layer insulated wire for a high-frequency transformer according to claim 1, characterized in that: The addition ratio of component 1, chlorobenzene and m-chloroperbenzoic acid in S3 is 10g:200-400mL:0.5-1g.

5. The method for preparing a heat-resistant flexible three-layer insulated wire for a high-frequency transformer according to claim 1, characterized in that: The mass ratio of PA66 and elastomer-modified glass fiber in S4 is 10:1-4.

6. The method for preparing a heat-resistant flexible three-layer insulated wire for a high-frequency transformer according to claim 1, characterized in that: The preparation method of the mercaptolated glass fiber comprises the following steps: adding high-temperature calcined glass fiber, γ-mercaptopropyltrimethoxysilane and deionized water into a reaction kettle for blending, controlling the temperature to 50-60° C., heat-insulating for 2-4 hours, washing with water and drying to obtain the mercaptolated glass fiber.

7. The method for preparing a heat-resistant flexible three-layer insulated wire for a high-frequency transformer according to claim 1, characterized in that: The method for preparing the first insulating polymer layer comprises the following steps: wrapping a polyimide film on the surface of a conducting wire to obtain the first insulating polymer layer.

8. The method for preparing a heat-resistant flexible three-layer insulated wire for a high-frequency transformer according to claim 1, characterized in that: The preparation method of the second insulating polymer layer comprises the following steps: passing a conductive wire with a first insulating polymer layer wrapped on its surface through an extruder die to coat a second insulating polymer material to obtain a second insulating polymer layer; the second insulating polymer material comprises the following raw materials in parts by weight: 15-35 parts of polytrimethylene terephthalate, 50-70 parts of polyethylene terephthalate, 5-10 parts of polybutylene terephthalate, 1-3 parts of a compatibilizer, and 1-2 parts of a masterbatch; the compatibilizer is maleic anhydride modified polyethylene.

9. The method for preparing a heat-resistant flexible three-layer insulated wire for a high-frequency transformer according to claim 1, characterized in that: The thickness of the first insulating polymer layer is 0.01-0.02mm; the thickness of the second insulating polymer layer is 0.02-0.05mm; the thickness of the nylon modified glass fiber outer layer is 0.08-0.15mm; the total thickness of the first insulating polymer layer, the second insulating polymer layer and the nylon modified glass fiber outer layer is 0.08-0.2mm.

10. A heat-resistant flexible three-layer insulated wire for a high-frequency transformer, characterized in that: Prepared by the preparation method described in any one of claims 1 to 9.