High-strength thermo-oxidative aging resistant waterborne epoxy insulating paint and preparation method thereof

Abstract

The invention discloses a high-strength thermo-oxidative aging resistant waterborne epoxy insulating paint and a preparation method thereof.The high-strength thermo-oxidative aging resistant waterborne epoxy insulating paint adopts high-temperature-resistant inorganic rare earth and a composition thereof and utilizes the 4f orbital characteristic of the rare earth to quench free radicals generated in the epoxy thermo-oxidative aging process, and the purpose of enhancing thermo-oxidative aging resistance of waterborne epoxy resin is achieved; the surface oxygen separation energy of the nano rare earth oxide is low, so that oxygen vacancies are easily formed, and the nano rare earth oxide has endogenous free radical capturing and quenching functions; under the action of heat and oxygen, weak bonds on alpha carbon of epoxy resin are broken, a large number of free radicals are generated, a free radical chain reaction is generated, a molecular chain structure is destroyed, a carbonyl product is generated, nano cerium oxide is applied to the waterborne epoxy insulating paint, free radicals generated by thermo-oxidative aging of epoxy are eliminated in a capture quenching mode, and the curing effect of the waterborne epoxy insulating paint is improved. The free radical chain reaction is terminated; the nano rare earth oxide can prevent thermo-oxidative aging of the epoxy resin; the nano oxide can enhance the mechanical property of the insulating paint.

Description

Technical Field

[0001] The invention relates to the technical field of insulating coatings, in particular to a high-strength thermal-oxidative-aging-resistant water-based epoxy insulating varnish and a preparation method thereof. Background Art

[0002] Insulating varnish is a coating with electrochemical, thermal, mechanical and chemical properties after curing. It provides insulation protection for copper wires and iron substrates, avoiding accidents such as leakage, spontaneous combustion and shutdown in production and life, and avoiding unnecessary losses of personnel and equipment. In recent years, with the increasing demand for renewable energy such as wind power and hydropower, pump motors have continuously put forward new requirements for the performance of insulating varnish.

[0003] Water-based epoxy resin insulating varnish uses water as solvent and has no volatile organic solvents, which meets environmental protection requirements; after curing, epoxy resin has the advantages of excellent mechanical strength, chemical resistance, electrical properties, moisture resistance, low shrinkage, and high cost performance. However, it still has various shortcomings. Affected by the heat and oxygen in the air under the use environment, its heat and oxygen aging resistance deteriorates, which seriously restricts the durability and reliability of motor copper wire in the application process.

[0004] Patent CN110283369A discloses a heat-resistant oxygen aging epoxidized natural rubber nanocomposite material and a preparation method thereof. The invention grafts a silane coupling agent onto the surface of graphene oxide, then grafts antioxidant molecules onto the graphene oxide, and then composites the graphene oxide grafted with the antioxidant with the epoxidized natural rubber through a tetrahydrofuran solution mixing method to obtain an epoxidized natural rubber nanocomposite material.

[0005] Patent CN115109390A discloses a composition for preparing heat-resistant and oxidative aging-resistant epoxy asphalt and its preparation method. The invention adds an organic hindered phenol 1010 antioxidant to a mixture of bisphenol A epoxy resin, a long carbon chain anhydride curing agent and a 50# base asphalt or a 70# base asphalt, and utilizes the antioxidant properties of 1010 to improve the aging resistance of the epoxy resin.

[0006] Patent CN104194109A discloses a heat-oxidative aging-resistant epoxidized natural rubber composite material and a preparation method thereof. By adding modified hydrotalcite to the epoxidized natural rubber latex, a large number of non-bridging hydroxyl groups on the surface of the hydrotalcite react with the epoxy groups in the epoxidized natural rubber, so that the hydrotalcite can better bond and disperse in the rubber particle system. At the same time, it can also absorb and neutralize the free acid generated during the aging process of the epoxidized natural rubber, thereby inhibiting the progress of the heat-oxidative aging process.

[0007] The anti-thermal oxidation method involved in the above patents mainly improves epoxy thermal oxidation by adding modified graphene, organic antioxidants and inorganic hydrotalcite.

[0008] Therefore, a high-strength thermal-oxidative-aging-resistant water-based epoxy insulating varnish and a preparation method thereof are proposed. Summary of the invention

[0009] To achieve the above object, the present invention provides the following technical solution: a high-strength thermal-oxidative-aging-resistant water-based epoxy insulating varnish, the raw materials of which are as follows: Waterborne epoxy resin, latent curing agent, water, dispersant, defoamer and nano rare earth oxide.

[0010] A method for preparing a high-strength thermal-oxidative-aging-resistant water-based epoxy insulating varnish comprises the following steps: S1, preparation of nano rare earth oxide: firstly, reagent grade cerium nitrate and lanthanum nitrate solution and reagent grade sodium hydroxide are subjected to precipitation reaction in a certain ratio; The precipitate is then filtered and washed to obtain a water-containing compound; Then put it into a high-temperature muffle furnace for sintering at a temperature of 1000-1300°C and keep it at a constant temperature for 2-4 hours before cooling to obtain a granular oxide; 40% of granular oxide, 59% of water, 1% of dispersant and an appropriate amount of zirconium beads were added into a high-speed grinder and ground to obtain a nano-cerium oxide aqueous solution, and then the solid content was measured for later use; S2, add water-based epoxy resin emulsion and latent curing agent into the pull cylinder in proportion, add deionized water, and disperse at high speed for 10-20 minutes at a dispersion speed of 1000r / min; S3, add the defoamer into the pull cylinder and continue to disperse for 10 minutes; S4, add the slurry obtained in S1 into the pulling cylinder, continue stirring for 20 minutes, and the dispersion speed is 2000r / min. Then the material can be filtered and packaged.

[0011] Preferably, in S1, the grinding time of 40% granular oxide, 59% water, 1% dispersant and an appropriate amount of zirconium beads has a start / stop ratio of 1 min / 5 min.

[0012] Preferably, in S1, 40% granular oxide, 59% water, 1% dispersant and an appropriate amount of zirconium beads need to be cyclically ground for 200 to 300 times, and the zirconium beads must be filtered after grinding.

[0013] Preferably, in S1, the cerium oxide particle size distribution of the obtained granular oxide is 100-500 nm.

[0014] Preferably, in S2, the pulling cylinder is specifically a dispersing cylinder which is a stirring container of a disperser.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention adopts high temperature resistant inorganic rare earth and its combination, and utilizes the 4f orbital characteristics of rare earth to quench the free radicals generated in the epoxy thermal oxidative aging process, thereby achieving the purpose of enhancing the thermal oxidative aging resistance of waterborne epoxy resin; Among them, the oxygen detachment energy on the surface of nano rare earth oxide is low, which makes it easy to form oxygen vacancies and has the function of capturing and quenching endogenous free radicals; Under the action of heat and oxygen, the weak bonds on the α carbon of epoxy resin are mainly broken, a large number of free radicals are generated, a free radical chain reaction occurs, the molecular chain structure is destroyed, and carbonyl products are generated. Applying nano-cerium oxide to water-based epoxy insulating paint can eliminate the free radicals generated by thermal oxidation aging of epoxy by capturing and quenching, thus terminating the free radical chain reaction. Adding nano rare earth oxides can effectively prevent the thermal oxidation aging of epoxy resin; In addition, the addition of nano-oxides can also enhance the mechanical properties of insulating paint. DETAILED DESCRIPTION

[0016] The present invention will be described in more detail below by way of examples, which are merely illustrative and do not in any way limit the scope of the present invention.

[0017] Example 1 In one aspect of the present invention, the present invention provides a technical solution: a high-strength thermal-oxidative-aging-resistant water-based epoxy insulating varnish, the raw materials of which are as follows: The invention comprises a water-based epoxy resin, a latent curing agent, water, a dispersant, a defoaming agent and a nano rare earth oxide; according to an embodiment of the present invention, the latent curing agent is a modified cyanamide curing agent; the water is deionized water prepared by a water making machine; the auxiliary agent is a dispersant and a defoaming agent, and the dispersant is UNIQ SPERSE 630 U, UNIQ SPERSE 650 U, UNIQ SPERSE 680 U, preferably one of the above; The defoaming agent is UNIQ FOAM 265 W, UNIQ FOAM 280W, UNIQ FOAM 265 W, preferably one of them; The nano rare earth oxide is prepared by chemical precipitation, high temperature sintering and grinding. The nano oxide is a combination of nano cerium oxide and cerium lanthanum oxide.

[0018] Preparation method: In the second aspect of the present invention, the present invention provides a method for preparing the polymer material film described above, the method comprising: preparing nano rare earth oxide, firstly, reacting reagent grade cerium nitrate and lanthanum nitrate solution with reagent grade sodium hydroxide in a certain proportion for precipitation reaction; then filtering and washing the precipitate to obtain a water-containing compound; then sintering it in a high-temperature muffle furnace, the sintering temperature is 1000~1300℃, and cooling at a constant temperature for 2-4h to obtain a granular oxide; adding 40% granular oxide, 59% water, 1% dispersant and an appropriate amount of zirconium beads into a high-speed grinder for grinding to obtain a nano cerium oxide aqueous solution, and then measuring the solid content for standby use; then adding a water-based epoxy resin emulsion and a latent curing agent into a pull cylinder in proportion, adding deionized water, and dispersing at high speed for 10-20min, with a dispersion speed of 1000r / min; adding a defoaming agent into the pull cylinder, and continuing to disperse for 10min; finally adding the slurry obtained in S1 into the pull cylinder, continuing to stir for 20min, with a dispersion speed of 2000r / min, and then filtering and discharging the material for packaging.

[0019] First, reagent-grade cerium nitrate and lanthanum nitrate solutions are reacted with reagent-grade sodium hydroxide for precipitation reaction, filtering, and washing to obtain a hydrated compound, and then the hydrated compound is sintered to obtain a granular oxide, in order to facilitate better and more uniform grinding of the particles in the next step; then, water-based epoxy resin emulsion, latent curing agent, ionized water, defoaming agent and slurry are added to the pull cylinder in turn for dispersion. The purpose of dispersion is to evenly disperse the solid matter in the carrier to form a stable dispersion system to reduce agglomeration / phase separation / precipitation.

[0020] The invention adopts high temperature resistant inorganic rare earth and its composition, utilizes the 4f orbital characteristics of rare earth, realizes the quenching of free radicals generated in the process of epoxy thermal oxidation aging, thereby achieving the purpose of enhancing the thermal oxidation aging resistance of waterborne epoxy resin; wherein, the oxygen separation energy on the surface of nano rare earth oxide is low, which makes it easy to form oxygen vacancies, and has the function of capturing and quenching endogenous free radicals; under the action of heat and oxygen, the weak bond on the α carbon of epoxy resin mainly breaks, generates a large number of free radicals, and a free radical chain reaction occurs, the molecular chain structure is destroyed, and a carbonyl product is generated. The application of nano cerium oxide to waterborne epoxy insulating paint can eliminate the free radicals generated by the thermal oxidation aging of epoxy by capturing and quenching, thereby terminating the free radical chain reaction; the addition of nano rare earth oxide can effectively prevent the thermal oxidation aging of epoxy resin; in addition, the addition of nano oxide can also enhance the mechanical properties of insulating paint.

[0021] According to an embodiment of the present invention, the grinding time of 40% granular oxide, 59% water, 1% dispersant and an appropriate amount of zirconium beads has a start / stop ratio of 1min / 5min. According to an embodiment of the present invention, the grinding of 40% granular oxide, 59% water and 1% dispersant is to ensure that the particle size of each substance remains consistent.

[0022] According to an embodiment of the present invention, 40% granular oxide, 59% water, 1% dispersant and an appropriate amount of zirconium beads need to be cyclically ground 200 to 300 times. After grinding, the zirconium beads must be filtered. According to an embodiment of the present invention, the zirconium beads must be filtered cleanly to avoid residues that affect subsequent processing or use.

[0023] According to an embodiment of the present invention, the particle size distribution of the cerium oxide obtained as the granular oxide is 100~500nm. According to an embodiment of the present invention, the cerium oxide with a particle size greater than 100~500nm needs to be reprocessed until it meets the requirements, while the cerium oxide with a particle size less than 100~500nm is not used.

[0024] According to an embodiment of the present invention, the pulling cylinder is specifically a dispersion cylinder which is a stirring container of a disperser. According to an embodiment of the present invention, the disperser is mainly used to disperse solid substances to form a stable dispersion system, thereby reducing the occurrence of precipitation problems.

[0025] The following table shows the main component ratios of water-based epoxy insulating paint: Table 1 Ratio of each ingredient The present invention is mainly tested with reference to GB 18445-2012 standard, and the test results are shown in the following table: Table 2 is the test results of the insulating paint performance of the present invention Example 2 1. A method for preparing a high-strength thermal-oxidative-aging-resistant water-based epoxy insulating varnish: S1, preparation of nano rare earth oxide: first, prepare reagent grade cerium nitrate and lanthanum nitrate in a mass ratio of 6:4 into an aqueous solution and react with reagent grade sodium hydroxide in a certain proportion for precipitation reaction; then, filter and wash the precipitate to obtain a water-containing compound; then put it into a high-temperature muffle furnace for sintering at a sintering temperature of 1000°C for a constant temperature time of 4 hours, cool it to obtain a granular oxide, add 40% oxide, 59% water, 1% UNIQ SPERSE 680 U, a dispersant and an appropriate amount of zirconium beads into a high-speed grinder for grinding, the grinding time is 1min / 5min, the grinding is circulated for 200 times, the zirconium beads are filtered, and a nano cerium oxide aqueous solution is obtained, wherein the cerium oxide particle size is mainly distributed in 300~500nm, the solid content is measured, and it is set aside; S2, add water-based epoxy resin emulsion and latent curing agent into the pull cylinder in proportion, add deionized water, and disperse at high speed for 20 minutes at a dispersion speed of 1000r / min; S3, add UNIQ FOAM 265 W defoamer to S2 and continue dispersing for 10 min; S4, add the slurry in S1 into S3 in proportion, continue stirring for 20 minutes, and the dispersion speed is 2000r / min; S5, filtering, discharging and packaging; The following table shows the main component ratios of water-based epoxy insulating paint: Table 2 Ratio of ingredients in Example 2 Effects of the embodiments The test was carried out according to GB 18445-2012 standard. The test results are shown in the following table: Table 3 Insulation paint performance test results of Example 2 Example 3 1. A method for preparing a high-strength thermal-oxidative-aging-resistant water-based epoxy insulating varnish: S1, preparation of nano rare earth oxide: first, prepare reagent grade cerium nitrate and lanthanum nitrate in a mass ratio of 6:4 into an aqueous solution and react with reagent grade sodium hydroxide in a certain ratio for precipitation reaction; then, filter and wash the precipitate to obtain a water-containing compound; then put it into a high-temperature muffle furnace for sintering at a sintering temperature of 1150°C for a constant temperature time of 3 hours, cool it to obtain a granular oxide, add 40% oxide, 59% water, 1% UNIQ SPERSE 650 U and UNIQ SPERSE 680 U mixed dispersant (ratio 4 / 6) and an appropriate amount of zirconium beads into a high-speed grinder for grinding, the grinding time is 1min / 5min, the grinding is circulated for 300 times, the zirconium beads are filtered, and a nano cerium oxide aqueous solution is obtained, wherein the cerium oxide particle size is mainly distributed in 100-400nm, the solid content is measured, and it is set aside; S2, add water-based epoxy resin emulsion and latent curing agent into the pull cylinder in proportion, add deionized water, and disperse at high speed for 15 minutes at a dispersion speed of 1000r / min; S3, add UNIQ FOAM 265 W defoamer to S2 and continue dispersing for 10 min; S4, add the slurry in S1 into S3 in proportion, continue stirring for 20 minutes, and the dispersion speed is 2000r / min; S5, filter out the material and package it.

[0026] The following table shows the main component ratios of water-based epoxy insulating paint: Table 4 Ratio of ingredients in Example 3 Effects of the embodiments The test was carried out according to GB 18445-2012 standard. The test results are shown in the following table: Table 5 Insulation varnish performance test results of Example 3 Example 4 1. A method for preparing a high-strength thermal-oxidative-aging-resistant water-based epoxy insulating varnish: S1, preparation of nano rare earth oxides: first, reagent-grade cerium nitrate and lanthanum nitrate are prepared into an aqueous solution in a mass ratio of 6:4 and reacted with reagent-grade sodium hydroxide in a certain ratio for precipitation reaction; then, the precipitate is filtered and washed to obtain a water-containing compound; then, the precipitate is placed in a high-temperature muffle furnace for sintering at a temperature of 1300°C for a constant temperature time of 2 hours, cooled to obtain a granular oxide, 40% oxide, 59% water, 1% UNIQ SPERSE 630 U dispersant and an appropriate amount of zirconium beads are added to a high-speed grinder for grinding, the grinding time is 1min / 5min, the grinding is circulated for 250 times, the zirconium beads are filtered, and a nano cerium oxide aqueous solution is obtained, wherein the cerium oxide particle size is mainly distributed in 200~400nm, the solid content is measured, and the mixture is set aside; S2, add water-based epoxy resin emulsion and latent curing agent into the pull cylinder in proportion, add deionized water, and disperse at high speed for 10 minutes at a dispersion speed of 1000r / min; S3, add defoamer UNIQ FOAM 280W into S2 and continue dispersing for 10 min; S4, add the slurry in S1 into S3 in proportion, continue stirring for 20 minutes, and the dispersion speed is 2000r / min; S5, filter out the material and package it.

[0027] The following table shows the main component ratios of water-based epoxy insulating paint: Table 6 Ratio of ingredients in Example 4 Effects of the embodiments The test was carried out according to GB 18445-2012 standard. The test results are shown in the following table: Table 7 Insulation varnish performance test results of Example 4 Example 5 1. A method for preparing a high-strength thermal-oxidative-aging-resistant water-based epoxy insulating varnish: S1, add water-based epoxy resin emulsion and latent curing agent into the pull cylinder in proportion, add deionized water, and disperse at high speed for 10-20 minutes at a dispersion speed of 1000r / min; S2, add UNIQ FOAM 265 W defoamer to S2 and continue dispersing for 10 min; S3, filter out the material and package it.

[0028] The following table shows the main component ratios of water-based epoxy insulating paint: Table 8 Ratio of ingredients in Example 5 Effects of the embodiments The test was carried out according to GB 18445-2012 standard. The test results are shown in the following table: Table 9 Test results of insulating paint performance in Example 5 Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-strength thermal-oxidative-aging-resistant water-based epoxy insulating varnish, characterized in that: The ingredients are as follows: It includes water-based epoxy resin, latent curing agent, water, dispersant, defoaming agent and nano rare earth oxide.

2. A method for preparing a high-strength thermal-oxidative-aging-resistant water-based epoxy insulating varnish, characterized in that: The following steps are involved: S1, preparation of nano rare earth oxide: firstly, reagent grade cerium nitrate and lanthanum nitrate solution and reagent grade sodium hydroxide are subjected to precipitation reaction in a certain ratio; The precipitate is then filtered and washed to obtain a water-containing compound; Then put it into a high-temperature muffle furnace for sintering at a temperature of 1000-1300°C and keep it at a constant temperature for 2-4 hours before cooling to obtain a granular oxide; 40% of granular oxide, 59% of water, 1% of dispersant and an appropriate amount of zirconium beads were added into a high-speed grinder and ground to obtain a nano-cerium oxide aqueous solution, and then the solid content was measured for later use; S2, add water-based epoxy resin emulsion and latent curing agent into the pull cylinder in proportion, add deionized water, and disperse at high speed for 10-20 minutes at a dispersion speed of 1000r / min; S3, add the defoamer into the pull cylinder and continue to disperse for 10 minutes; S4, add the slurry obtained in S1 into the pulling cylinder, continue stirring for 20 minutes, and the dispersion speed is 2000r / min. Then the material can be filtered and packaged.

3. A method for preparing a high-strength heat-oxidation-resistant water-based epoxy insulating varnish according to claim 2, characterized in that: In S1, 40% granular oxide, 59% water, 1% dispersant and appropriate amount of zirconium beads were ground at a start / stop ratio of 1 min / 5 min.

4. A method for preparing a high-strength heat-oxidation-resistant water-based epoxy insulating varnish according to claim 2, characterized in that: In S1, 40% granular oxide, 59% water, 1% dispersant and an appropriate amount of zirconium beads need to be cyclically ground 200 to 300 times, and the zirconium beads must be filtered after grinding.

5. A method for preparing a high-strength heat-oxidation-resistant water-based epoxy insulating varnish according to claim 2, characterized in that: In S1, the cerium oxide particle size distribution of the obtained granular oxide is 100-500 nm.

6. A method for preparing a high-strength heat-oxidation-resistant water-based epoxy insulating varnish according to claim 2, characterized in that: In S2, the pulling cylinder is specifically a dispersion cylinder which is a stirring container of a disperser.

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