Outdoor high-flexibility polyurethane wire enamel and preparation method thereof

Abstract

The invention relates to the technical field of wire enamel, in particular to outdoor high-flexibility polyurethane wire enamel and a preparation method of the outdoor high-flexibility polyurethane wire enamel. The high-flexibility polyurethane wire enamel is prepared from the following raw materials in parts by weight: 45-55 parts of weather-resistant high-flexibility polyester resin, 8-12 parts of a weather-resistant curing agent, 5-10 parts of a drier solution and 25-35 parts of a solvent. According to the high-flexibility polyurethane wire enamel capable of being used outdoors, a main film forming substance is saturated polyester resin rich in aliphatic dibasic acid and dihydric alcohol; the content of aromatic dibasic acids such as terephthalic acid and isophthalic acid is greatly reduced, so that a paint film can be ensured to have extremely high flexibility, and the outdoor durability of the paint film can be greatly improved.

Description

Technical Field

[0001] This invention relates to the field of enameled wire coating technology, and in particular to a high-flexibility polyurethane enameled wire coating suitable for outdoor use and its preparation method. Background Technology

[0002] With the rapid development of new energy vehicles, the market size of enameled wires for new energy vehicles is growing year by year, and various cable materials are also showing the characteristics of diversified technical requirements and high performance requirements. Cable materials for new energy vehicles need to meet the following main performance requirements:

[0003] High and low temperature resistance: The cable material needs to be able to remain stable under extreme temperatures, typically requiring no cracking in a temperature range of -40℃ to 125℃ and a voltage resistance of 1kV.

[0004] Oil-resistant, water-resistant, and acid and alkali-resistant: Cable materials need to be able to resist the erosion of oils such as gasoline, diesel, and engine oil, while also being able to withstand water immersion and corrosion in acid and alkali environments.

[0005] Tear and crack resistance: Cable materials need to have high tear resistance, usually requiring a tear strength greater than 15 N / mm², or even higher.

[0006] Flexibility: The cable must maintain good electrical performance under repeated bending, typically requiring it to continue working normally after 30,000 bends.

[0007] Abrasion and crush resistance: Cables need to be able to resist mechanical abrasion and crushing, which is usually verified through scraping and dragging tests.

[0008] Flexibility: The cable should have good flexibility to facilitate installation and wiring.

[0009] Environmentally friendly and flame-retardant: Cable materials need to meet environmental standards and have characteristics such as low smoke, halogen-free, and flame retardant.

[0010] UV resistance: Cable materials need to be able to resist the aging effects of ultraviolet rays and maintain stable electrical performance over a long period of time.

[0011] High voltage / high current transmission: Cables need to be able to withstand high voltage and high current. High voltage harnesses used in new energy vehicles typically need to withstand 600V voltage and 300A current.

[0012] Electromagnetic interference shielding: Cables need to have good electromagnetic shielding performance to reduce the impact of electromagnetic interference on the system.

[0013] Existing polyurethane enameled wire enamels generally consist of polyisocyanate imide and aromatic polyol esters. Their flexibility, tested using the tensile winding method, is 1 day / 20% at a test temperature of 23℃. Slight cracking occurs in the enamel film at -40℃. Furthermore, aromatic polyol esters have poor weather resistance, making them unsuitable for long-term outdoor use. In short, it is difficult for any existing polyurethane enameled wire enamel suppliers to simultaneously meet the comprehensive performance requirements of low-temperature flexibility and outdoor durability. Therefore, we propose a high-flexibility polyurethane enameled wire enamel suitable for outdoor use and its preparation method. This enamel maintains good flexibility even at -40℃, addressing the comprehensive performance requirements of commonly used enameled wire enamels and cable materials. Summary of the Invention

[0014] The purpose of this invention is to overcome the shortcomings of the prior art and to propose a high-flexibility polyurethane enameled wire coating for outdoor use and its preparation method.

[0015] A type of high-flexibility polyurethane enameled wire coating suitable for outdoor use is composed of the following raw materials in parts by weight: 45-55 parts of weather-resistant high-flexibility polyester resin, 8-12 parts of weather-resistant curing agent, 5-10 parts of drying agent solution, and 25-35 parts of solvent.

[0016] Preferably, the preparation method of the weather-resistant and highly flexible polyester resin includes the following steps: (1) adding diacid, diol, polyol and catalyst into a sealed container and mixing evenly; (2) heating the above materials to 110-130°C under nitrogen protection, starting the stirrer, continuing to heat, raising the temperature to 155-165°C and holding for 20-40 minutes; (3) continuing to heat to 175-185°C and holding for 1.5-2.5 hours, then raising the temperature of the reaction materials to 240-250°C at a heating rate of 0.5-1°C / min, holding the reaction until the reaction is complete; (4) stopping the nitrogen flow, reducing the pressure and removing impurities; (5) cooling the sealed container to below 100°C, drawing it into a diluent container containing diluent, stirring evenly to obtain the finished resin.

[0017] Preferably, in the preparation process of the weather-resistant and highly flexible polyester resin, the raw materials, by molar amount, are: 25-40 parts of diacid, 20-30 parts of diol, 5-10 parts of polyol, and 0.1-0.2 parts of catalyst;

[0018] The mass fraction of diluent in the finished resin is 25%-35%;

[0019] The dicarboxylic acid is a mixture of adipic acid, azelaic acid, 1,3-cyclopentanedicarboxylic acid, 1,3-cyclobutanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid, wherein the molar ratio of cycloalkane dicarboxylic acid to straight-chain dicarboxylic acid is 0.5-3:1; the diol is one or more of 1,4-butanediol, 1,6-hexanediol, and neopentyl glycol; the polyol is one or more of glycerol, trimethylolpropane, trimethylolethane, and pentaerythritol; the catalyst is antimony trioxide; and the diluent is selected from at least one of the following: a dicarboxylic acid ester mixture DBE, propylene glycol methyl ether acetate, xylene, butyl acetate, methyl isobutyl ketone, and cyclohexanone.

[0020] Preferably, the weather-resistant curing agent is a trimer-blocked form of hexamethylene diisocyanate.

[0021] Preferably, the method for preparing the drying agent solution includes the following steps:

[0022] (1) Weigh magnesium nitrate and aluminum nitrate and dissolve them in deionized water. Adjust the pH to 8-13 with 1-3 mol / L sodium hydroxide aqueous solution. Stir the reaction at 70-100℃ for 1-3 hours, then keep it warm for crystallization for 10-18 hours. After the reaction is complete, add silane coupling agent and continue stirring for 1-2 hours. After filtration, washing, drying and grinding, obtain silane coupling agent modified magnesium-aluminum hydrotalcite.

[0023] (2) The magnesium-aluminum hydrotalcite modified with silane coupling agent is placed in the stripping agent for stripping to obtain a stripping hydrotalcite colloidal solution. Then, a drying agent is added and mixed evenly to obtain a drying agent solution.

[0024] The molar ratio of magnesium nitrate to aluminum nitrate is 2:1, the mass ratio of magnesium nitrate to deionized water is 1:6-10, the mass ratio of magnesium nitrate to silane coupling agent is 1:0.1-0.3, the mass ratio of magnesium nitrate to stripping agent is 1:3-5, and the mass ratio of drying agent to stripping agent is 0.01-0.05:1.

[0025] Preferably, the drying agent is dibutyltin dilaurate, and the silane coupling agent is one of KH550, KH560, and KH570.

[0026] Preferably, the stripping agent is selected from xylene, n-butanol, butyl acetate, methyl isobutyl ketone, and cyclohexanone.

[0027] Preferably, the solvent is selected from at least one of the following: a mixture of diesters (DBE), propylene glycol methyl ether acetate, xylene, n-butanol, butyl acetate, methyl isobutyl ketone, and cyclohexanone.

[0028] Preferably, the method includes the following steps: weighing the weather-resistant high-flexibility polyester resin, weather-resistant curing agent, drier solution, and solvent according to the specified proportions, adding them to a mixing tank, and stirring evenly with a high-speed mixer at a temperature of 15-35℃ to obtain a high-flexibility enameled wire enamel suitable for outdoor use.

[0029] Preferably, the high-speed mixer rotates at a speed of 1200-1800 rpm.

[0030] The beneficial effects of this invention are:

[0031] 1. The high-flexibility polyurethane enameled wire varnish proposed in this invention can be used outdoors. The main film-forming substance (weather-resistant and highly flexible polyester resin) is a saturated polyester resin rich in aliphatic dicarboxylic acids. The content of aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid is greatly reduced. This can ensure that the paint film has extremely high flexibility and greatly improve the outdoor durability of the paint film.

[0032] 2. The high-flexibility polyurethane enameled wire varnish proposed in this invention can be used outdoors. Its weather-resistant curing agent is an aliphatic polyisocyanate blocked curing agent. A typical example is Covestro's BL3370MPA, which is a trimer of hexamethylene diisocyanate (HDI). This curing agent can not only give the varnish film excellent flexibility, but also excellent outdoor durability and good insulation performance.

[0033] 3. The high-flexibility polyurethane enameled wire paint for outdoor use proposed in this invention uses a drying agent solution as its drying component, which has a good dispersion effect. The drying agent can better promote the reaction between -NCO and -OH, making the paint film more uniform and dense after film formation.

[0034] 4. The high-flexibility polyurethane enameled wire varnish proposed in this invention, applicable to outdoor use, involves the preparation of magnesium-aluminum hydrotalcite during the drying agent solution preparation process. Magnesium-aluminum hydrotalcite is first prepared, and after modification with a silane coupling agent, its dispersion performance in organic matter is improved. After being peeled off with a stripping agent, the hydrotalcite is formed into a single sheet-like structure. The large specific surface area of ​​the hydrotalcite and the silane coupling agent on its surface facilitate its bonding with the drying agent. After the enameled wire varnish forms a film, the sheet-like hydrotalcite can form a nano-barrier network, improving the insulation performance of the enameled wire varnish. Furthermore, the hydrotalcite can scatter ultraviolet light to a certain extent, further enhancing the coating's anti-aging properties.

[0035] 5. The high-flexibility polyurethane enameled wire coating proposed in this invention can be used outdoors. Secondly, the film-forming substance (weather-resistant curing agent) does not contain aromatic benzene ring structure, which effectively solves the problems of excessive rigidity, insufficient flexibility and poor weather resistance of enameled wire coating. Detailed Implementation

[0036] The present invention will be further explained below with reference to specific embodiments.

[0037] In the following embodiments, unless otherwise specified, the test methods or experimental methods are conventional methods; reagents and materials, unless otherwise specified, are obtained from conventional commercial sources or prepared using conventional methods. Specifically: diacids, diols, polyols, antimony trioxide, weather-resistant curing agents, solvents, and drying agents were purchased from Daikin Industries, Shanghai Kaiyin Chemical, Yantai Wanhua Chemical, Guangzhou Haoyi New Materials Co., Ltd., Weng Kai'er Co., Ltd., Shanghai McLean Co., Ltd., and Cardley Co., Ltd.; solvents were purchased from Shanghai Tikem Co., Ltd. and Jiangsu Sanmu Group.

[0038] In Example 1, a type of high-flexibility polyurethane enameled wire coating suitable for outdoor use is composed of the following raw materials in parts by weight: 45 parts of weather-resistant high-flexibility polyester resin, 8 parts of weather-resistant curing agent, 5 parts of drying agent solution, and 25 parts of solvent.

[0039] The preparation method of weather-resistant and highly flexible polyester resin includes the following steps: (1) adding diacid, diol, polyol and catalyst into a sealed container and mixing evenly; (2) heating the above materials to 110°C under nitrogen protection, starting the stirrer, continuing to heat, raising the temperature to 155°C and holding for 20 minutes; (3) continuing to heat to 175°C and holding for 1.5 hours, then raising the temperature of the reaction materials to 240°C at a heating rate of 0.5°C / min, holding the reaction until the reaction is complete; (4) stopping the nitrogen flow, reducing the pressure and removing impurities; (5) cooling the sealed container to 90°C, drawing it into a diluent container containing diluent, stirring evenly to obtain the finished resin, the mass fraction of diluent in the finished resin is 30%, and the diluent is selected from xylene.

[0040] In the preparation process of weather-resistant and highly flexible polyester resin, the raw materials, by molar ratio, are: 25 parts of dicarboxylic acid, 20 parts of diol, 5 parts of polyol and 0.1 parts of catalyst;

[0041] The dicarboxylic acid is a mixture of adipic acid and 1,3-cyclopentadicarboxylic acid, wherein the molar ratio of cyclic dicarboxylic acid to straight-chain dicarboxylic acid is 0.5:1; the diol is 1,4-butanediol; the polyol is glycerol; and the catalyst is antimony trioxide.

[0042] The weather-resistant curing agent is a trimer-blocked form of hexamethylene diisocyanate.

[0043] The preparation method of the drying agent solution includes the following steps:

[0044] (1) Weigh magnesium nitrate and aluminum nitrate and dissolve them in deionized water. Adjust the pH to 8 with 1 mol / L sodium hydroxide aqueous solution. Stir the reaction at 70°C for 1 hour and then keep it warm for 10 hours to crystallize. After the reaction is complete, add silane coupling agent and continue stirring for 1 hour. After filtration, washing, drying and grinding, obtain silane coupling agent modified magnesium-aluminum hydrotalcite.

[0045] (2) The magnesium-aluminum hydrotalcite modified with silane coupling agent is placed in the stripping agent for stripping to obtain a stripping hydrotalcite colloidal solution. Then, a drying agent is added and mixed evenly to obtain a drying agent solution.

[0046] The molar ratio of magnesium nitrate to aluminum nitrate is 2:1, the mass ratio of magnesium nitrate to deionized water is 1:6, the mass ratio of magnesium nitrate to silane coupling agent is 1:0.1, the mass ratio of magnesium nitrate to stripping agent is 1:3, and the mass ratio of drying agent to stripping agent is 0.01:1.

[0047] The drying agent is dibutyltin dilaurate, and the silane coupling agent is KH550.

[0048] The stripping agent is selected from xylene.

[0049] The solvent is selected from a mixture of diester ester mixture DBE and xylene in a volume ratio of 1:1.

[0050] A method for preparing a high-flexibility polyurethane enameled wire varnish for outdoor use includes the following steps: weighing weather-resistant high-flexibility polyester resin, weather-resistant curing agent, drier solution, and solvent according to the specified proportions, adding them to a mixing tank, and stirring evenly with a high-speed mixer at a temperature of 15°C to obtain a high-flexibility enameled wire varnish suitable for outdoor use.

[0051] The high-speed mixer operates at 1200 rpm.

[0052] In Example 2, a type of high-flexibility polyurethane enameled wire coating suitable for outdoor use is composed of the following raw materials in parts by weight: 55 parts of weather-resistant high-flexibility polyester resin, 12 parts of weather-resistant curing agent, 10 parts of drying agent solution, and 35 parts of solvent.

[0053] The preparation method of weather-resistant and highly flexible polyester resin includes the following steps: (1) adding diacid, diol, polyol and catalyst into a sealed container and mixing evenly; (2) heating the above materials to 130°C under nitrogen protection, starting the stirrer, continuing to heat, raising the temperature to 165°C and holding for 40 minutes; (3) continuing to heat to 185°C and holding for 2.5 hours, then raising the temperature of the reaction materials to 250°C at a heating rate of 1°C / min, holding the reaction until the reaction is complete; (4) stopping the nitrogen flow, reducing the pressure and removing impurities; (5) cooling the sealed container to 95°C, drawing it into a diluent container, stirring evenly to obtain the finished resin, the mass fraction of the diluent in the finished resin is 25%, and the diluent is selected from the diacid acid mixture DBE.

[0054] In the preparation of weather-resistant and highly flexible polyester resin, the raw materials, by molar ratio, are: 40 parts of diacid, 30 parts of diol, 10 parts of polyol and 0.2 parts of catalyst;

[0055] The dicarboxylic acid is a mixture of azelaic acid and 1,3-cyclobutanedicarboxylic acid, wherein the molar ratio of cyclic dicarboxylic acid to straight-chain dicarboxylic acid is 3:1; the diol is a mixture of 1,4-butanediol and 1,6-hexanediol in a volume ratio of 1:1; the polyol is trimethylolpropane; and the catalyst is antimony trioxide.

[0056] The weather-resistant curing agent is a trimer-blocked form of hexamethylene diisocyanate.

[0057] The preparation method of the drying agent solution includes the following steps:

[0058] (1) Weigh magnesium nitrate and aluminum nitrate and dissolve them in deionized water. Adjust the pH to 13 with 3 mol / L sodium hydroxide aqueous solution. Stir the reaction at 100°C for 3 hours and then keep it warm for 18 hours to crystallize. After the reaction is complete, add silane coupling agent and continue stirring for 2 hours. After filtration, washing, drying and grinding, obtain silane coupling agent modified magnesium-aluminum hydrotalcite.

[0059] (2) The magnesium-aluminum hydrotalcite modified with silane coupling agent is placed in the stripping agent for stripping to obtain a stripping hydrotalcite colloidal solution. Then, a drying agent is added and mixed evenly to obtain a drying agent solution.

[0060] The molar ratio of magnesium nitrate to aluminum nitrate is 2:1, the mass ratio of magnesium nitrate to deionized water is 1:10, the mass ratio of magnesium nitrate to silane coupling agent is 1:0.3, the mass ratio of magnesium nitrate to stripping agent is 1:5, and the mass ratio of drying agent to stripping agent is 0.05:1.

[0061] The drying agent is dibutyltin dilaurate, and the silane coupling agent is KH560.

[0062] The stripping agent is selected from n-butanol.

[0063] The solvent is selected from a mixture of propylene glycol methyl ether acetate and n-butanol in a volume ratio of 1:1.

[0064] A method for preparing a high-flexibility polyurethane enameled wire varnish for outdoor use includes the following steps: weighing weather-resistant high-flexibility polyester resin, weather-resistant curing agent, drier solution, and solvent according to the specified proportions, adding them to a mixing tank, and stirring evenly with a high-speed mixer at a temperature of 35°C to obtain a high-flexibility enameled wire varnish suitable for outdoor use.

[0065] The high-speed mixer operates at 1800 rpm.

[0066] In Example 3, a type of high-flexibility polyurethane enameled wire coating suitable for outdoor use is composed of the following raw materials in parts by weight: 50 parts of weather-resistant high-flexibility polyester resin, 10 parts of weather-resistant curing agent, 7 parts of drying agent solution, and 30 parts of solvent.

[0067] The preparation method of weather-resistant and highly flexible polyester resin includes the following steps: (1) adding diacid, diol, polyol and catalyst into a sealed container and mixing evenly; (2) heating the above materials to 120°C under nitrogen protection, starting the stirrer, continuing to heat, raising the temperature to 160°C and holding for 30 minutes; (3) continuing to heat to 180°C and holding for 2 hours, then raising the temperature of the reaction materials to 245°C at a heating rate of 0.8°C / min, holding the reaction until the reaction is complete; (4) stopping the nitrogen flow, reducing the pressure and removing impurities; (5) cooling the sealed container to 80°C, drawing it into a diluent container containing diluent, stirring evenly to obtain the finished resin, the mass fraction of diluent in the finished resin is 35%, and the diluent is selected from propylene glycol methyl ether acetate.

[0068] In the preparation process of weather-resistant and highly flexible polyester resin, the raw materials, by molar ratio, are: 30 parts of diacid, 25 parts of diol, 5 parts of polyol and 0.15 parts of catalyst;

[0069] The dicarboxylic acid is a mixture of azelaic acid and 1,4-cyclohexanedicarboxylic acid, wherein the molar ratio of cyclic dicarboxylic acid to straight-chain dicarboxylic acid is 2:1; the diol is neopentyl glycol, the polyol is trimethylolethane, and the catalyst is antimony trioxide.

[0070] The weather-resistant curing agent is a trimer-blocked form of hexamethylene diisocyanate.

[0071] The preparation method of the drying agent solution includes the following steps:

[0072] (1) Weigh magnesium nitrate and aluminum nitrate and dissolve them in deionized water. Adjust the pH to 11 with 2 mol / L sodium hydroxide aqueous solution. Stir the reaction at 90°C for 2 h and then keep it warm for 16 h to crystallize. After the reaction is complete, add silane coupling agent and continue stirring for 1.5 h. After filtration, washing, drying and grinding, obtain silane coupling agent modified magnesium-aluminum hydrotalcite.

[0073] (2) The magnesium-aluminum hydrotalcite modified with silane coupling agent is placed in the stripping agent for stripping to obtain a stripping hydrotalcite colloidal solution. Then, a drying agent is added and mixed evenly to obtain a drying agent solution.

[0074] The molar ratio of magnesium nitrate to aluminum nitrate is 2:1, the mass ratio of magnesium nitrate to deionized water is 1:8, the mass ratio of magnesium nitrate to silane coupling agent is 1:0.2, the mass ratio of magnesium nitrate to stripping agent is 1:4, and the mass ratio of drying agent to stripping agent is 0.04:1.

[0075] The drying agent is dibutyltin dilaurate, and the silane coupling agent is KH570.

[0076] The stripping agent is selected from cyclohexanone.

[0077] The solvent is selected from a mixture of xylene and cyclohexanone in a volume ratio of 1:1.

[0078] A method for preparing a high-flexibility polyurethane enameled wire varnish for outdoor use includes the following steps: weighing weather-resistant high-flexibility polyester resin, weather-resistant curing agent, drier solution, and solvent according to the specified proportions, adding them to a mixing tank, and stirring evenly with a high-speed mixer at a temperature of 25°C to obtain a high-flexibility enameled wire varnish suitable for outdoor use.

[0079] The high-speed mixer operates at 1600 rpm.

[0080] In Example 4, a type of high-flexibility polyurethane enameled wire coating suitable for outdoor use is composed of the following raw materials in parts by weight: 50 parts of weather-resistant high-flexibility polyester resin, 10 parts of weather-resistant curing agent, 7 parts of drying agent solution, and 30 parts of solvent.

[0081] The preparation method of weather-resistant and highly flexible polyester resin includes the following steps: (1) adding diacid, diol, polyol and catalyst into a sealed container and mixing evenly; (2) heating the above materials to 120°C under nitrogen protection, starting the stirrer, continuing to heat, raising the temperature to 160°C and holding for 30 minutes; (3) continuing to heat to 180°C and holding for 2 hours, then raising the temperature of the reaction materials to 245°C at a heating rate of 0.8°C / min, holding the reaction until the reaction is complete; (4) stopping the nitrogen flow, reducing the pressure and removing impurities; (5) cooling the sealed container to 98°C, drawing it into a diluent container containing diluent, stirring evenly to obtain the finished resin, the mass fraction of diluent in the finished resin is 28%, and the diluent is selected from butyl acetate.

[0082] In the preparation process of weather-resistant and highly flexible polyester resin, the raw materials, by molar ratio, are: 30 parts of diacid, 25 parts of diol, 5 parts of polyol and 0.15 parts of catalyst;

[0083] The dicarboxylic acid is a mixture of azelaic acid and 1,4-cyclohexanedicarboxylic acid, wherein the molar ratio of cyclic dicarboxylic acid to straight-chain dicarboxylic acid is 2:1; the diol is neopentyl glycol, the polyol is trimethylolethane, and the catalyst is antimony trioxide.

[0084] The weather-resistant curing agent is a trimer-blocked form of hexamethylene diisocyanate.

[0085] The preparation method of the drying agent solution includes the following steps:

[0086] (1) Weigh magnesium nitrate and aluminum nitrate and dissolve them in deionized water. Adjust the pH to 8 with 1 mol / L sodium hydroxide aqueous solution. Stir the reaction at 70°C for 1 hour and then keep it warm for 10 hours to crystallize. After the reaction is complete, add silane coupling agent and continue stirring for 1 hour. After filtration, washing, drying and grinding, obtain silane coupling agent modified magnesium-aluminum hydrotalcite.

[0087] (2) The magnesium-aluminum hydrotalcite modified with silane coupling agent is placed in the stripping agent for stripping to obtain a stripping hydrotalcite colloidal solution. Then, a drying agent is added and mixed evenly to obtain a drying agent solution.

[0088] The molar ratio of magnesium nitrate to aluminum nitrate is 2:1, the mass ratio of magnesium nitrate to deionized water is 1:6, the mass ratio of magnesium nitrate to silane coupling agent is 1:0.1, the mass ratio of magnesium nitrate to stripping agent is 1:3, and the mass ratio of drying agent to stripping agent is 0.01:1.

[0089] The drying agent is dibutyltin dilaurate, and the silane coupling agent is KH570.

[0090] The stripping agent is selected from butyl acetate.

[0091] The solvent is selected from a mixture of xylene and butyl acetate in a volume ratio of 1:1.

[0092] A method for preparing a high-flexibility polyurethane enameled wire varnish for outdoor use includes the following steps: weighing weather-resistant high-flexibility polyester resin, weather-resistant curing agent, drier solution, and solvent according to the specified proportions, adding them to a mixing tank, and stirring evenly with a high-speed mixer at a temperature of 30°C to obtain a high-flexibility enameled wire varnish suitable for outdoor use.

[0093] The high-speed mixer operates at 1600 rpm.

[0094] In Example 5, a type of high-flexibility polyurethane enameled wire coating suitable for outdoor use is composed of the following raw materials in parts by weight: 50 parts of weather-resistant high-flexibility polyester resin, 10 parts of weather-resistant curing agent, 7 parts of drying agent solution, and 30 parts of solvent.

[0095] The preparation method of weather-resistant and highly flexible polyester resin includes the following steps: (1) adding diacid, diol, polyol and catalyst into a sealed container and mixing evenly; (2) heating the above materials to 120°C under nitrogen protection, starting the stirrer, continuing to heat, raising the temperature to 160°C and holding for 30 minutes; (3) continuing to heat to 180°C and holding for 2 hours, then raising the temperature of the reaction materials to 245°C at a heating rate of 0.8°C / min, holding the reaction until the reaction is complete; (4) stopping the nitrogen flow, reducing the pressure and removing impurities; (5) cooling the sealed container to 85°C, drawing it into a diluent container containing diluent, stirring evenly to obtain the finished resin, the mass fraction of diluent in the finished resin is 32%, and the diluent is a mixture of methyl isobutyl ketone and cyclohexanone in a volume ratio of 1:1.

[0096] In the preparation process of weather-resistant and highly flexible polyester resin, the raw materials, by molar ratio, are: 30 parts of diacid, 25 parts of diol, 5 parts of polyol and 0.15 parts of catalyst;

[0097] The dicarboxylic acid is a mixture of adipic acid and 1,4-cyclohexanedicarboxylic acid, wherein the molar ratio of cyclic dicarboxylic acid to straight-chain dicarboxylic acid is 2:1; the diol is neopentyl glycol, the polyol is trimethylolethane, and the catalyst is antimony trioxide.

[0098] The weather-resistant curing agent is a trimer-blocked form of hexamethylene diisocyanate.

[0099] The preparation method of the drying agent solution includes the following steps:

[0100] (1) Weigh magnesium nitrate and aluminum nitrate and dissolve them in deionized water. Adjust the pH to 13 with 3 mol / L sodium hydroxide aqueous solution. Stir the reaction at 100°C for 3 hours and then keep it warm for 18 hours to crystallize. After the reaction is complete, add silane coupling agent and continue stirring for 2 hours. After filtration, washing, drying and grinding, obtain silane coupling agent modified magnesium-aluminum hydrotalcite.

[0101] (2) The magnesium-aluminum hydrotalcite modified with silane coupling agent is placed in the stripping agent for stripping to obtain a stripping hydrotalcite colloidal solution. Then, a drying agent is added and mixed evenly to obtain a drying agent solution.

[0102] The molar ratio of magnesium nitrate to aluminum nitrate is 2:1, the mass ratio of magnesium nitrate to deionized water is 1:10, the mass ratio of magnesium nitrate to silane coupling agent is 1:0.3, the mass ratio of magnesium nitrate to stripping agent is 1:5, and the mass ratio of drying agent to stripping agent is 0.05:1.

[0103] The drying agent is dibutyltin dilaurate, and the silane coupling agent is KH560.

[0104] The stripping agent is selected from methyl isobutyl ketone.

[0105] The solvent is selected from a mixture of methyl isobutyl ketone and cyclohexanone in a volume ratio of 2:1.

[0106] A method for preparing a high-flexibility polyurethane enameled wire varnish for outdoor use includes the following steps: weighing weather-resistant high-flexibility polyester resin, weather-resistant curing agent, drier solution, and solvent according to the specified proportions, adding them to a mixing tank, and stirring evenly with a high-speed mixer at a temperature of 30°C to obtain a high-flexibility enameled wire varnish suitable for outdoor use.

[0107] The high-speed mixer operates at 1600 rpm.

[0108] Comparative Example 1: STU56 polyurethane enameled wire enamel from a major domestic manufacturer was selected. Its main components are polyisocyanate imide and aromatic polyol ester.

[0109] Comparative Example 2: Purchased 6300 series polyurethane enameled wire enamel from a wholly foreign-owned enterprise. Its main components are polyisocyanate imide and aromatic polyol ester.

[0110] Comparative Example 3, compared with Example 3, added a drying agent instead of a drying agent solution, wherein the mass of the drying agent was the same as that of the drying agent in Example 3.

[0111] In Comparative Example 4, compared with Example 3, the preparation method of the drying agent solution includes the following steps: placing the silane coupling agent in the stripping agent, then adding the drying agent, mixing evenly, and obtaining the drying agent solution;

[0112] The mass ratio of silane coupling agent to stripping agent is 1:0.05, and the mass ratio of drying agent to stripping agent is 0.05:1.

[0113] The drying agent is dibutyltin dilaurate, and the silane coupling agent is KH560.

[0114] The enameled wire varnishes prepared in Examples 1-5 and Comparative Examples 1-4 were respectively applied to the plates to obtain nine groups of plates with enameled wire varnish coatings corresponding to Examples 1-5 and Comparative Examples 1-4. The xenon lamp aging effect of the above nine groups of plates was tested according to the method of national standard GB / T 1865-2009, and the test results are shown in Table 1.

[0115] Table 1

[0116]

[0117] The enameled wire enamels prepared in Examples 1-5 and Comparative Examples 1-4 were applied to copper wires with a diameter of 0.8 mm, and the enamel film thickness was uniformly 0.07 mm. The tensile winding flexibility and breakdown voltage at room temperature of the enamel film were tested according to the national standard GB / T 4074.3-2024 series. The test results are shown in Table 2.

[0118] Table 2

[0119]

[0120] As can be seen from Table 1, the weather-resistant enameled wire varnishes prepared in Examples 1-5 have excellent weather resistance, good adhesion, and good breakdown voltage. Compared with Example 1, Comparative Examples 1-2 have a higher proportion of aromatic structures in the main resin, resulting in a significant decrease in weather resistance, making them unsuitable for outdoor use, and their stretching and winding flexibility at low temperatures is generally poor. In Comparative Example 3, the addition of a drier instead of a drier solution resulted in a certain decrease in weather resistance, and the breakdown voltage at room temperature was inferior to that of Examples 1-5. In Comparative Example 4, its overall performance was better than that of Comparative Example 3, but it was still somewhat lower than that of Examples 1-5.

[0121] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A type of high-flexibility polyurethane enameled wire coating suitable for outdoor use, characterized in that, It is composed of the following raw materials in parts by weight: 45-55 parts of weather-resistant and highly flexible polyester resin, 8-12 parts of weather-resistant curing agent, 5-10 parts of drying agent solution and 25-35 parts of solvent.

2. The high-flexibility polyurethane enameled wire coating for outdoor use according to claim 1, characterized in that, The preparation method of the weather-resistant and highly flexible polyester resin includes the following steps: (1) adding diacid, diol, polyol and catalyst into a sealed container and mixing evenly; (2) heating the above materials to 110-130℃ under nitrogen protection, starting the stir, continuing to heat, raising the temperature to 155-165℃ and holding for 20-40 minutes; (3) continuing to heat to 175-185℃ and holding for 1.5-2.5 hours, then raising the temperature of the reaction materials to 240-250℃ at a heating rate of 0.5-1℃ / min, holding the reaction until the reaction is complete; (4) stopping the nitrogen flow, reducing the pressure and removing impurities; (5) cooling the sealed container to below 100℃, drawing it into a diluent container containing diluent, stirring evenly to obtain the finished resin.

3. The high-flexibility polyurethane enameled wire coating for outdoor use according to claim 2, characterized in that, In the preparation process of the weather-resistant and highly flexible polyester resin, the raw materials, by molar amount, are: 25-40 parts of diacid, 20-30 parts of diol, 5-10 parts of polyol and 0.1-0.2 parts of catalyst; The mass fraction of diluent in the finished resin is 25%-35%; The dicarboxylic acid is a mixture of adipic acid, azelaic acid, 1,3-cyclopentanedicarboxylic acid, 1,3-cyclobutanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid, wherein the molar ratio of cycloalkane dicarboxylic acid to straight-chain dicarboxylic acid is 0.5-3:1; the diol is one or more of 1,4-butanediol, 1,6-hexanediol, and neopentyl glycol; the polyol is one or more of glycerol, trimethylolpropane, trimethylolethane, and pentaerythritol; the catalyst is antimony trioxide; and the diluent is selected from at least one of the following: a dicarboxylic acid ester mixture DBE, propylene glycol methyl ether acetate, xylene, butyl acetate, methyl isobutyl ketone, and cyclohexanone.

4. The high-flexibility polyurethane enameled wire coating for outdoor use according to claim 1, characterized in that, The weather-resistant curing agent is a trimer-blocked form of hexamethylene diisocyanate.

5. The high-flexibility polyurethane enameled wire coating for outdoor use according to claim 1, characterized in that, The preparation method of the drying agent solution includes the following steps: (1) Weigh magnesium nitrate and aluminum nitrate and dissolve them in deionized water. Adjust the pH to 8-13 with 1-3 mol / L sodium hydroxide aqueous solution. Stir the reaction at 70-100℃ for 1-3 hours, then keep it warm for crystallization for 10-18 hours. After the reaction is complete, add silane coupling agent and continue stirring for 1-2 hours. After filtration, washing, drying and grinding, obtain silane coupling agent modified magnesium-aluminum hydrotalcite. (2) The magnesium-aluminum hydrotalcite modified with silane coupling agent is placed in the stripping agent for stripping to obtain a stripping hydrotalcite colloidal solution. Then, a drying agent is added and mixed evenly to obtain a drying agent solution. The molar ratio of magnesium nitrate to aluminum nitrate is 2:1, the mass ratio of magnesium nitrate to deionized water is 1:6-10, the mass ratio of magnesium nitrate to silane coupling agent is 1:0.1-0.3, the mass ratio of magnesium nitrate to stripping agent is 1:3-5, and the mass ratio of drying agent to stripping agent is 0.01-0.05:

1.

6. The high-flexibility polyurethane enameled wire coating for outdoor use according to claim 5, characterized in that, The drying agent is dibutyltin dilaurate, and the silane coupling agent is one of KH550, KH560 and KH570.

7. The high-flexibility polyurethane enameled wire coating for outdoor use according to claim 5, characterized in that, The stripping agent is selected from xylene, n-butanol, butyl acetate, methyl isobutyl ketone, and cyclohexanone.

8. The high-flexibility polyurethane enameled wire coating for outdoor use according to claim 1, characterized in that, The solvent is selected from at least one of the following: a mixture of diesters (DBE), propylene glycol methyl ether acetate, xylene, n-butanol, butyl acetate, methyl isobutyl ketone, and cyclohexanone.

9. A method for preparing a high-flexibility polyurethane enameled wire coating for outdoor use according to any one of claims 1-8, characterized in that, Includes the following steps: Weigh out the weather-resistant, highly flexible polyester resin, weather-resistant curing agent, drier solution, and solvent according to the specified proportions, add them to a mixing tank, and stir evenly with a high-speed mixer at a temperature of 15-35℃ to obtain a highly flexible enameled wire enamel suitable for outdoor use.

10. A method for preparing a high-flexibility polyurethane enameled wire coating for outdoor use according to claim 9, characterized in that, The high-speed mixer operates at a speed of 1200-1800 rpm.

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