Electrodeposition coating for forming a flame-retardant insulating polymer coating, preparation method and the flame-retardant insulating polymer coating

Abstract

The present invention discloses an electrodeposition coating for forming a flame-retardant insulating polymer coating, which is formed by mixing an epoxy resin emulsion and a color paste in deionized water; by weight percentage, the epoxy resin emulsion comprises: 52%-62% of a functional modified epoxy component A, 15%-25% of a functional modified epoxy component B, 1%-5% of a fluorinated nano-silica sol, 20%-30% of a fully blocked isocyanate, 1.7%-4.8% of glacial acetic acid, and the balance of deionized water. This epoxy resin material can adhere to the surfaces of metal components such as steel, aluminum and its alloys, copper and its alloys, form a dense polymer material coating with a thickness of 15-30 microns, the neutral salt spray can reach 1200 hours, can withstand a voltage breakdown of 1k-40kV, and has a self-extinguishing effect, the oxygen index is 29, and the flame retardant performance reaches UL94-V0 level.

Description

Technical Field

[0001] The present invention relates to the technical field of electrophoretic coatings, and particularly to an electrodeposition coating for forming a flame-retardant insulating polymer coating, a preparation method thereof, and the flame-retardant insulating polymer coating. Background Art

[0002] With the development of fields such as transportation, construction, and aerospace, people's requirements for safe and environmentally friendly coatings are increasing day by day, and the demand for flame-retardant insulating polymer coatings is gradually increasing. This coating has excellent flame-retardant performance, good insulation performance, excellent weather resistance and chemical resistance, and can effectively reduce the occurrence of current leakage and fire accidents. It is one of the important development directions in the future coating market.

[0003] Cathodic electrophoretic coating is a special coating method that forms a protective film on the surface of a substrate through cationic electrodeposition. It has characteristics such as high leveling property, high throwing power, full coverage, and high automation degree, and is widely used in fields such as metal surface protection, electronic equipment protection, and automotive coating. At present, most cationic electrodeposition coatings on the market are mainly composed of resin emulsions and color pastes, and have defects such as weak water resistance, anti-corrosion performance, and flame-retardant performance, which seriously restrict the popularization and application scope of this coating. Therefore, designing a preparation method for an anodic electrodeposition coating with high flame-retardant performance and insulation performance to improve the deficiencies of existing coatings has become a problem that needs to be solved by those skilled in the art. Summary of the Invention

[0004] The purpose of the present invention is to introduce a functional resin into the electrophoretic coating, thereby improving the breakdown strength of the electrophoretic coating after film formation and drying by electrophoresis. At the same time, an efficient flame-retardant structure is introduced. Through electrodeposition technology, the epoxy resin material can adhere to the surfaces of metal parts such as steel, aluminum and its alloys, and copper and its alloys, forming a dense polymer material coating with a thickness of 15 - 30 microns. The neutral salt spray can reach 1200 hours, can withstand voltage breakdown of 1k - 40kV, has a self-extinguishing effect, the oxygen index is 29, and the flame-retardant performance reaches UL94-V0 level.

[0005] In the first aspect, an electrodeposition coating for forming a flame-retardant insulating polymer coating provided by the present invention is formed by mixing an epoxy resin emulsion and a color paste in deionized water; calculated by weight percentage, the epoxy resin emulsion includes:

[0006] 52% - 62% of functional modified epoxy component A,

[0007] 15% - 25% of functional modified epoxy component B,

[0008] 1% - 5% of fluorinated nano-silica sol,

[0009] 20% - 30% of fully blocked isocyanate,

[0010] Glacial acetic acid 1.7% - 4.8%,

[0011] with the balance being deionized water.

[0012] In certain embodiments, the functional modified epoxy component A includes the following preparation method:

[0013] Add an inert organic solvent, hexafluorobisphenol A, and an organic base to F51 phenolic epoxy resin. While stirring, heat up to 130 - 150 °C and keep warm for 1 - 2 hours to obtain an epoxy resin with an epoxy equivalent of 500 - 1500. Then cool down to 85 - 100 °C, add an amine compound containing active hydrogen. After adding, heat up to 100 - 120 °C and keep warm for 3 hours, then cool down and discharge to obtain the functional modified epoxy component A.

[0014] In certain embodiments, the amine compound containing active hydrogen is at least one primary secondary amine or a polyamine containing both secondary amine groups and tertiary amine groups or a mixture thereof. The primary secondary amine is an alkylamine, a ketimine, an alkanolamine, or a mixture thereof. The alkylamine is diethylamine, methyl isobutylamine, or dibutylamine. The ketimine is hydroxymethylethylenediamine ketimine or diethylenetriamine ketimine. The alkanolamine solvent is diethanolamine or N - methylethanolamine. The organic base is selected from triethylamine, N - N dimethylbenzylamine, triethanolamine, dimethylethanolamine, triphenylphosphine, or methyldiethanolamine. The inert organic solvent is an alcohol solvent, an alcohol ether solvent, a toluene solvent, or a ketone solvent. The alcohol solvent is n - butanol or isobutanol. The alcohol ether solvent is ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, or diethylene glycol monobutyl ether. The toluene solvent is toluene, o - xylene, or m - xylene. The ketone solvent is methyl isobutyl ketone;

[0015] The addition amount of the organic base is 1‰ - 5‰ of the addition amount of F51 phenolic epoxy resin. The addition amount of the amine compound containing active hydrogen, calculated by the number of moles of active hydrogen, has a ratio of 0.8 - 0.9:1 to the number of moles of epoxy groups of the chain - extended epoxy resin.

[0016] In certain embodiments, the functional modified epoxy component B includes the following preparation method:

[0017] Add DOPO - modified phenolic epoxy resin, bisphenol A epoxy resin, and an inert organic solvent into a four - necked flask. Heat up to 100 - 110 °C. After the materials are completely dissolved, add an organic base as a catalyst and heat up to 125 - 155 °C and keep warm for 1 - 2 hours to obtain an epoxy resin with an epoxy equivalent of 600 - 1000. Then cool down to 85 - 95 °C, add an amine compound containing active hydrogen. After adding, heat up to 100 - 120 °C and keep warm for 3 hours, then cool down and discharge to obtain the functional modified epoxy component B.

[0018] In some embodiments, the amine compound containing active hydrogen is at least one primary secondary amine or a polyamine containing both secondary amine groups and tertiary amine groups or a mixture thereof. The primary secondary amine is an alkylamine, a ketimine, an alkanolamine or a mixture thereof. The alkylamine is diethylamine, methyl isobutylamine or dibutylamine. The ketimine is hydroxymethylethylenediamine ketimine or diethylenetriamine ketimine. The alkanolamine is diethanolamine or N-methylethanolamine. The organic base is triethylamine, N,N-dimethylbenzylamine, triethanolamine, dimethylethanolamine, triphenylphosphine or methyldiethanolamine. The inert organic solvent is an alcohol solvent, an alcohol ether solvent, a toluene solvent or a ketone solvent. The alcohol solvent is n-butanol or isobutanol. The alcohol ether solvent is ethylene glycol monobutyl ether, ethylene glycol monohexyl ether or diethylene glycol monobutyl ether. The toluene solvent is toluene, o-xylene or m-xylene. The ketone solvent is methyl isobutyl ketone;

[0019] The addition amount of the organic base is 1‰ - 3‰ of the addition amount of the DOPO-modified phenolic epoxy resin. The addition amount of the secondary amine compound containing active hydrogen, calculated by the number of moles of active hydrogen, has a ratio of 0.8 - 0.9:1 to the number of moles of epoxy groups of the epoxy resin chain-extended with bisphenol A.

[0020] In some embodiments, the fluorinated nano-silica sol includes the following preparation method:

[0021] Mechanically stir and disperse the silica sol aqueous solution and tetraethyl orthosilicate in deionized water, and dropwise add a polymer dispersant and a fluorosilane. Continuously heat at 50 °C in a water bath for 12 - 24 h. After suction filtration, wash with deionized water 3 - 5 times to obtain the fluorinated nano-silica sol.

[0022] In some embodiments, the fluorinated nano-silica sol includes the following components in parts by weight:

[0023] Silica sol aqueous solution 10 - 15 parts,

[0024] Tetraethyl orthosilicate 0.3 - 0.6 part,

[0025] Deionized water 80 - 100 parts,

[0026] Polymer dispersant 0.1 - 0.5 part,

[0027] Lactic acid 0.02 - 0.2 part

[0028] Fluorosilane 0.2 - 0.5 part;

[0029] Wherein: the silica sol aqueous solution is obtained by adding nano-silica sol with a particle size of 4-10 nm, a solid content of 15%, and a pH value of 8-9 to deionized water and adjusting the pH value to 5.5-6.5 with lactic acid; the fluorosilane is a fluoroalkylsilane with a carbon chain of 5-8; the polymer dispersant is at least one of polyamine salt and polyvinylpyrrolidone.

[0030] In certain embodiments, the preparation method of the fully blocked isocyanate includes the following:

[0031] In the case of using organotin as a catalyst, a mixture of 4,4-dicyclohexylmethane diisocyanate and a solvent is heated to 45-55 °C with stirring, and then a blocking agent is added dropwise. After the addition is completed in 1.5-2 hours, the mixture is kept warm for 1.5-2 hours to obtain the fully blocked isocyanate.

[0032] In certain embodiments, the blocking agent of the fully blocked isocyanate is an organic compound containing active hydrogen, and the organic compound includes alcohol compounds, alcohol ether compounds or ketoxime compounds. The alcohol compounds are methanol or ethanol, the alcohol ether compounds are ethylene glycol monomethyl ether, ethylene glycol monoethyl ether or ethylene glycol monobutyl ether, and the ketoxime compound is butanone oxime; the organotin catalyst is stannous octoate or dibutyltin dilaurate; the solvent includes ester solvents or ketone solvents. The ester solvents are ethyl acetate or butyl acetate, and the ketone solvents are methyl ethyl ketone or methyl isobutyl ketone.

[0033] In a second aspect, the method for preparing an electro-deposition coating for forming a flame-retardant insulating polymer coating provided by the present invention includes the following steps:

[0034] It is prepared by mixing an epoxy resin emulsion and a color paste in deionized water;

[0035] Wherein: the preparation method of the epoxy resin emulsion component is: sequentially adding a functional modified epoxy component A, a functional modified epoxy component B and a fully blocked isocyanate into a four-necked flask, heating to 60-70 °C, stirring evenly and keeping warm for 30 min, then adding glacial acetic acid for neutralization, stirring at 60 °C for 0.5-2.5 h and slowly adding deionized water. After adding, continue stirring for 30 min, adding sodium fluoride nano-silica sol under high-speed stirring, mixing evenly and then decompressing and evacuating to remove the solvent to obtain an electrophoretic paint emulsion component with a solid content of 25-40%;

[0036] The conductivity of the deionized water is controlled below 5 us / cm. In certain embodiments, the color paste is the HL-1701E black paste from the products of HLS Company.

[0037] In certain embodiments, the mixing ratio of epoxy resin emulsion and HL-1701E black paste is preferably in the range of 10:1 to 4:1 based on the solid content mass ratio. After mixing, deionized water is added to dilute the solid content to 10 to 22%, and the target electrodeposition coating is matured for more than 24 hours under low-speed stirring to obtain.

[0038] In a third aspect, the present invention provides a method for preparing a flame retardant insulating polymer coating, comprising the following steps:

[0039] A metal steel plate is used as the electrode material at both ends of the power supply, and the electrode material is immersed in the electrodeposition coating described in any one of claims 1 to 8. After electrophoresis is performed at a voltage of 100-350V for 2-5 minutes, the cathode material is taken out, rinsed with deionized water, and cured at 150-300°C for 10-50 minutes to obtain the flame-retardant insulating polymer coating on the surface of the cathode material.

[0040] The following beneficial effects are achieved by adopting the solution of the present invention:

[0041] (1) Hexafluorobisphenol A participates in chain extension and introduces CF into the main structure of the resin 3 Group; CF 3 The introduction of groups introduces deep traps in the modified epoxy resin, which slows down the decay rate of surface charge. The introduction of deep traps will inhibit the migration of carriers in the body, resulting in an increase in volume resistivity and breakdown field strength after modification, effectively improving the withstand voltage insulation effect of the coating;

[0042] (2) Among the selected cross-linking agents, the active hydrogen-containing blocking agent, HMDI, is selected as the main body, which effectively provides toughness while taking into account the resistance, balancing the loss of flexibility caused by the excessive rigidity of the phenolic main body. At the same time, the aliphatic ring main body can provide a certain pressure resistance, effectively improving the insulation effect of the overall coating;

[0043] (3) CF is introduced into the main resin structure 3 , which can effectively balance the possible coating defects caused by the strong rigidity of the main chain;

[0044] (4) Introducing DOPO structure into the main chain of the component and aminated the main chain, which effectively improves the electrophoretic film formation. The synergistic flame retardant effect of NP greatly enhances the flame retardant effect of the coating;

[0045] (5) The introduction of phosphorus-containing heterocycles and fluorine-containing structures into the main chain can effectively improve the corrosion resistance of the coating;

[0046] (6) The addition of fluorinated nano-silica sol can effectively form hydrophobic sites in the coating, hindering the invasion, transmission and diffusion of water molecules, improving the hydrophobicity and moisture absorption resistance of the coating, thereby further improving the anti-corrosion and insulation properties of the coating. Description of the Drawings

[0047] Figure 1 It is a surface microscopic morphology diagram of the flame-retardant insulating polymer coating;

[0048] Figure 2 It is a picture of the surface droplet nucleation of the flame-retardant insulating polymer coating under condensation conditions. Detailed Implementation Modes

[0049] The technical solutions of the present invention will be described in detail below in conjunction with each embodiment.

[0050] Embodiment 1

[0051] 1. Prepare the functional modified epoxy component A (component P1)

[0052] The specific formula is as follows:

[0053]

[0054] In a four-necked flask equipped with a thermometer, a stirring paddle, and a condenser, add 631 phenolic epoxy resin (produced by South Asia Company, general brand F51), then add hexafluorobisphenol A and methyl isobutyl ketone solvent. Add N,N-dimethylformamide as a catalyst, turn on the nitrogen protection, heat up to 145 °C, keep warm for 1.5 hours, then cool down to 90 °C, slowly add N-methylethanolamine under rapid stirring, and after adding, naturally heat up to 110 °C, keep warm for 3 hours and then cool down and discharge to obtain the functional modified component A, which is placed in a clean and sealed container for standby.

[0055] 2. Prepare the functional modified epoxy component B (component P2)

[0056] The specific formula is as follows:

[0057]

[0058] In a four-necked flask equipped with a thermometer, a stirring paddle, and a condenser, add DOPO-modified phenolic epoxy resin (Chengdu Keyi, CE5300), then add bisphenol A and methyl isobutyl ketone solvent. Add triphenylphosphine as a catalyst, turn on the nitrogen protection, heat up to 150 °C, keep warm for 2 hours, then cool down to 90 °C, slowly add a mixture of N-methylethanolamine and KT22 under rapid stirring, and after adding, naturally heat up to 115 °C, keep warm for 3 hours and then cool down and discharge to obtain the functional modified component B, which is placed in a clean and sealed container for standby.

[0059] 3. Prepare the fully enclosed isocyanate component (component P3)

[0060] The specific formula is as follows:

[0061]

[0062] In a four-necked flask equipped with a thermometer, a stirring paddle, and a condenser, add HMDI, dibutyltin dilaurate, and methyl isobutyl ketone. Under nitrogen protection, heat to 50 °C, and then dropwise add ethylene glycol monoethyl ether. During the dropping process, control the temperature at 50 - 60 °C. After about two hours of dropping, continue to keep the temperature at 60 °C for two hours. After the NCO groups react completely, a fully blocked isocyanate is obtained.

[0063] 4. Preparation of sodium fluoride nanosilica sol

[0064] The specific formulation is as follows:

[0065]

[0066] In a four-necked flask equipped with a thermometer, a stirring paddle, and a condenser, add nanosilica sol to deionized water, adjust the pH value to 5.5 - 6.5 with lactic acid to obtain an aqueous solution of silica sol, and then add tetraethyl orthosilicate, polycarboxylate, and fluorosilane. Continuously heat in a water bath at 50 °C for 12 h. After suction filtration, wash with deionized water 3 - 5 times to obtain fluorinated nanosilica sol.

[0067] 5. Preparation of the resin emulsion 1 of the present invention

[0068] The specific formulation is as follows:

[0069]

[0070] In a four-necked flask equipped with a thermometer, a stirring paddle, and a condenser, as shown in the table. Sequentially add component P1 (which needs to be preheated to make it fluid), component P2 (which needs to be preheated to make it fluid), and component P3. After heating to 60 °C, stir evenly and keep the temperature for 30 minutes, then add glacial acetic acid for neutralization, stir at 60 °C for 1 hour, slowly add deionized water under stirring. After adding, continue to stir for 30 minutes, add sodium fluoride nanosilica sol under high-speed stirring, and after mixing evenly, reduce the pressure and vacuum to remove the solvent to obtain an electrophoretic paint emulsion component with a solid content of 34%.

[0071] 6. Preparation of the electrophoretic coating of the present invention and electrophoretic coating

[0072] The specific formulation is as follows:

[0073]

[0074] After mixing according to the formula shown in the table, a cathodic electrophoretic coating is prepared, in which the conductivity of deionized water is controlled below 5 us / cm, and the black paste selects the existing high-performance black paste products of HLS Company. The specific preparation is made by dispersing 30 parts of a general quaternary ammonium salt-modified epoxy resin, 65 parts of kaolin, 12 parts of carbon black, 3 parts of dibutyltin oxide and 100 parts of deionized water, and then grinding with a sand mill until the fineness is less than 15 μm.

[0075] The electrophoretic coating prepared according to the above scheme is placed in an electrophoresis tank and cured for 48 hours to obtain a well-cured working solution 1 of cathodic electrophoretic paint.

[0076] Example 2

[0077] 1. Preparation of functional modified epoxy component A (component P1)

[0078] The specific formula is as follows:

[0079]

[0080] In a four-necked flask equipped with a thermometer, a stirring paddle and a condenser, add 631 phenolic epoxy resin (produced by South Asia Company, general brand F51), then add hexafluorobisphenol A and n-butanol solvent. Add triethanolamine as a catalyst, turn on nitrogen protection, heat up to 130 °C, keep warm for 2 hours, then cool down to 85 °C, slowly add methyl isobutylamine under rapid stirring, and after adding, naturally heat up to 100 °C, keep warm for 3 hours and then cool down and discharge to obtain functional modified component A, which is placed in a clean and sealed container for standby.

[0081] 2. Preparation of functional modified epoxy component B (component P2)

[0082] The specific formula is as follows:

[0083]

[0084] In a four-necked flask equipped with a thermometer, a stirring paddle and a condenser, add DOPO-modified phenolic epoxy resin (Chengdu Keyi, CE5300), then add bisphenol A and n-butanol solvent. Add dimethylethanolamine as a catalyst, turn on nitrogen protection, heat up to 125 °C, keep warm for 1.5 hours, then cool down to 85 °C, slowly add a mixture of diethanolamine and KT22 under rapid stirring, and after adding, naturally heat up to 100 °C, keep warm for 3 hours and then cool down and discharge to obtain functional modified component B, which is placed in a clean and sealed container for standby.

[0085] 3. Preparation of fully enclosed isocyanate component (component P3)

[0086] The specific formula is as follows:

[0087]

[0088] In a four-necked flask equipped with a thermometer, a stirring paddle, and a condenser, add HMDI, stannous octoate, and ethyl acetate. Under nitrogen protection, heat to 50 °C, and then dropwise add methanol. During the dropping process, control the temperature at 50 - 60 °C. After about two hours of dropping, continue to keep the temperature at 60 °C for two hours. After the NCO groups have completely reacted, a fully blocked isocyanate is obtained.

[0089] 4. Preparation of sodium fluoride nanosilica solution

[0090] The specific formulation is as follows in the table:

[0091]

[0092] In a four-necked flask equipped with a thermometer, a stirring paddle, and a condenser, add nanosilica sol to deionized water, and adjust the pH value to 5.5 - 6.5 with lactic acid to obtain an aqueous silica sol solution. Subsequently, add tetraethyl orthosilicate, polycarboxylate, and fluorosilane, and continuously heat in a water bath at 50 °C for 24 h. After suction filtration, wash with deionized water 3 - 5 times to obtain fluorinated nanosilica sol.

[0093] 5. Preparation of the resin emulsion 2 of the present invention

[0094] The specific formulation is as follows in the table:

[0095]

[0096] In a four-necked flask equipped with a thermometer, a stirring paddle, and a condenser, as shown in the table. Sequentially add component P1 (which needs to be preheated to make it fluid), component P2 (which needs to be preheated to make it fluid), and component P3. After heating to 60 °C, stir evenly and keep the temperature for 30 minutes, then add glacial acetic acid for neutralization, stir at 60 °C for 1 hour, slowly add deionized water under stirring, continue to stir for 30 minutes after adding, and add sodium fluoride nanosilica sol under high-speed stirring. After mixing evenly, reduce the pressure and vacuum to remove the solvent to obtain an electrophoretic paint emulsion component with a solid content of 34%.

[0097] 6. Preparation of the electrophoretic coating of the present invention and electrophoretic coating

[0098] The specific formulation is as follows in the table:

[0099]

[0100] Mix according to the formulation shown in the table to prepare a cathodic electrophoretic coating, wherein the conductivity of deionized water is controlled below 5 us / cm, and the black paste selects the existing high-performance black paste product of HLS Company. The specific preparation is obtained by dispersing 30 parts of epoxy resin modified with a general quaternary ammonium salt, 65 parts of kaolin, 12 parts of carbon black, 3 parts of dibutyltin oxide, and 100 parts of deionized water, and then grinding with a sand mill to a fineness of less than 15 μm.

[0101] Example 3

[0102] 1. Preparation of functional modified epoxy component A (component P1)

[0103] The specific formula is as follows:[[]]END]]

[0104]

[0105] In a four-necked flask equipped with a thermometer, a stirring paddle, and a condenser, add 631 phenolic epoxy resin (produced by South Asia Company, general brand F51), then add hexafluorobisphenol A and o-xylene solvent. Add dimethylethanolamine as a catalyst, start nitrogen protection, heat up to 150 °C, keep warm for 1 hour, then cool down to 100 °C, and slowly add hydroxymethyl ethylenediamine ketimine under rapid stirring. After adding, naturally heat up to 120 °C, keep warm for 3 hours, and then cool down and discharge to obtain functional modified component A, which is placed in a clean and sealed container for standby.

[0106] 2. Preparation of functional modified epoxy component B (component P2)

[0107] The specific formula is as follows:[[]]END]]

[0108]

[0109] In a four-necked flask equipped with a thermometer, a stirring paddle, and a condenser, add DOPO-modified phenolic epoxy resin (Chengdu Keyi, CE5300), then add bisphenol A and ethylene glycol monobutyl ether solvent. Add triethanolamine as a catalyst, start nitrogen protection, heat up to 155 °C, keep warm for 2 hours, then cool down to 95 °C, and slowly add a mixture of dibutylamine and KT22 under rapid stirring. After adding, naturally heat up to 120 °C, keep warm for 3 hours, and then cool down and discharge to obtain functional modified component B, which is placed in a clean and sealed container for standby.

[0110] 3. Preparation of fully blocked isocyanate component (component P3)

[0111] The specific formula is as follows:[[]]END]]

[0112]

[0113] In a four-necked flask equipped with a thermometer, a stirring paddle, and a condenser, add HMDI, dibutyltin dilaurate, and butyl acetate. Under nitrogen protection, heat up to 50 °C, and then dropwise add ethylene glycol monobutyl ether. Control the temperature at 50 - 60 °C during the dropping process. After about two hours of dropping, continue to keep warm at 60 °C for two hours until the NCO group reacts completely to obtain a fully blocked isocyanate.

[0114] 4. Preparation of sodium fluoride nanosilica solution

[0115] The specific formula is as follows:[[]]END]]

[0116]

[0117] In a four-necked flask equipped with a thermometer, a stirring paddle, and a condenser, the nano-silica solution was added to deionized water, and the pH value was adjusted to 5.5 - 6.5 with lactic acid to obtain a silica sol aqueous solution. Subsequently, tetraethyl orthosilicate, polycarboxylate, and fluorosilane were added, and the mixture was continuously heated in a water bath at 50 °C for 12 h. After suction filtration, it was washed 3 - 5 times with deionized water to obtain fluorinated nano-silica sol.

[0118] 5. Preparation of the resin emulsion of the present invention 3

[0119] The specific formulation is as follows:

[0120]

[0121] In a four-necked flask equipped with a thermometer, a stirring paddle, and a condenser, as shown in the table. Component P1 (which needs to be preheated to make it fluid), Component P2 (which needs to be preheated to make it fluid), and Component P3 were added in sequence. After heating to 70 °C, it was stirred evenly and kept warm for 30 minutes, then neutralized with glacial acetic acid, stirred at 60 °C for 1 hour, slowly added deionized water under stirring, continued to stir for 30 minutes after adding, and added fluorinated sodium nano-silica sol under high-speed stirring. After mixing evenly, the solvent was removed by vacuum pumping under reduced pressure to obtain an electrophoretic paint emulsion component with a solid content of 34%.

[0122] 6. Preparation of the electrophoretic coating of the present invention and electrophoretic coating

[0123] The specific formulation is as follows:

[0124]

[0125] According to the formulation shown in the table, it was mixed to prepare a cathodic electrophoretic coating, in which the conductivity of deionized water was controlled below 5 μS / cm, and the black paste was selected from the existing high-performance black paste products of HLS Company. The specific preparation was obtained by dispersing 30 parts of an epoxy resin modified with a general quaternary ammonium salt, 65 parts of kaolin, 12 parts of carbon black, 3 parts of dibutyltin oxide, and 100 parts of deionized water, and grinding with a sand mill to a fineness of less than 15 μm.

[0126] Comparative Example 1

[0127] Preparation of a conventional electrophoretic coating and electrophoretic coating

[0128] The specific formulation is as follows:

[0129]

[0130] The cathode electrophoretic coating is prepared by mixing according to the formula shown in the table, wherein the conductivity of the deionized water is controlled below 5 us / cm, the black slurry is the same product as in Example 1, and the emulsion is HL-1701 emulsion, wherein the HL-1701 product is a high-performance cathode electrophoretic product maturely used on the market by HLS Company, and the solid content is the same as that of the emulsion in Example 1.

[0131] The electrophoretic coating prepared according to the above scheme was placed in an electrophoretic tank and aged for 48 hours to obtain a well-aged cathode electrophoretic paint working solution 2.

[0132] Performance Testing

[0133] A comprehensive evaluation of cathodic electrophoretic paint working fluids 1 and 2 was conducted, and the relevant evaluation results are shown in the following table:

[0134]

[0135] It can be seen from Table 1 that, compared with conventional high-performance electrophoretic coatings, the electrophoretic coating prepared in the present invention has significantly improved voltage resistance and flame retardancy.

[0136] The good water-repellent properties of the super-hydrophobic surface give the coating excellent moisture-proof properties. Figure 1 As shown in the figure, the modification of the resin and the addition of fluorinated nano-silica sol form micron-sized aggregates that are evenly distributed on the surface, successfully constructing a micro-nano composite rough structure to ensure the excellent super-hydrophobic properties of the coating. Figure 2 As shown, under condensation conditions, the air cavity pressure generated by the Laplace effect can effectively prevent water molecules from penetrating, and the water maintains a stable Cassie-Baxter state on the surface when the two come into contact, and the droplets are difficult to wet the coating, and can only condense and grow up in a spherical form on the coating surface. Water vapor will first nucleate and generate droplets of smaller size on the surface of super-hydrophobic activated carbon, and droplet condensation will occur. As the droplets continue to condense, droplets of different sizes in the local range will merge, and when the condensed droplets increase to a certain size, the adhesion of the super-hydrophobic surface will be eliminated, and self-driven bouncing will occur, so that the condensed droplets will be separated from the coating surface, and the nucleation-merging-bouncing process of water vapor will continue to occur at the position where the droplets are separated, and it will be carried out continuously over and over again, effectively preventing the entry of water vapor, and then playing a moisture-proof role. Therefore, the coating prepared by the present invention has excellent moisture resistance, can effectively reduce the coating breakdown phenomenon caused by the infiltration of water molecules, improve the breakdown voltage of the coating, and give the coating good insulation.

[0137] In summary: the flame retardant insulating electrophoretic coating of the present invention has the following advantages:

[0138] (1) Hexafluorobisphenol A participates in chain extension and introduces CF into the main structure of the resin 3 Group; CF3 The introduction of groups introduces deep traps in the modified epoxy resin, which slows down the decay rate of surface charge. The introduction of deep traps will inhibit the migration of carriers in the body, resulting in an increase in volume resistivity and breakdown field strength after modification, effectively improving the withstand voltage insulation effect of the coating;

[0139] (2) Among the selected cross-linking agents, the active hydrogen-containing blocking agent, HMDI, is selected as the main body, which effectively provides toughness while taking into account the resistance, balancing the loss of flexibility caused by the excessive rigidity of the phenolic main body. At the same time, the aliphatic ring main body can provide a certain pressure resistance, effectively improving the insulation effect of the overall coating;

[0140] (3) CF is introduced into the main resin structure 3 , which can effectively balance the possible coating defects caused by the strong rigidity of the main chain;

[0141] (4) Introducing DOPO structure into the main chain of the component and aminated the main chain, which effectively improves the electrophoretic film formation. The synergistic flame retardant effect of NP greatly enhances the flame retardant effect of the coating;

[0142] (5) The introduction of phosphorus-containing heterocycles and fluorine-containing structures into the main chain can effectively improve the corrosion resistance of the coating;

[0143] (6) The addition of fluorinated nano-silica sol can effectively form hydrophobic sites in the coating, hindering the invasion, transmission and diffusion of water molecules, improving the hydrophobicity and moisture absorption resistance of the coating, thereby further improving the anti-corrosion and insulation properties of the coating.

[0144] It will be clear to those skilled in the art that various modifications to the above embodiments may be made without departing from the overall spirit and concept of the present invention. All of these modifications fall within the scope of protection of the present invention. The protection scheme of the present invention shall be subject to the claims attached to the present invention.

Claims

1. An electrodeposition coating for forming a flame-retardant insulating polymer coating, which is formed by mixing an epoxy resin emulsion and a color paste in deionized water; Characterized in that, By weight percentage, the epoxy resin emulsion includes: 52%-62% of functional modified epoxy component A, 15%-25% of functional modified epoxy component B, 1%-5% of fluorinated nano-silica sol, 20%-30% of fully enclosed isocyanate, 1.7%-4.8% of glacial acetic acid, The balance of deionized water; The functional modified epoxy component A includes the following preparation method: Add an inert organic solvent, hexafluorobisphenol A and an organic base to F51 phenolic epoxy resin, heat up to 130-150 °C under stirring, keep warm for 1-2 hours, then an epoxy resin with an epoxy equivalent of 500-1500 is obtained. Cool down to 85-100 °C, add an amine compound containing active hydrogen, after adding, heat up to 100-120 °C and keep warm for 3 hours, then cool down and discharge to obtain the functional modified epoxy component A; The functional modified epoxy component B includes the following preparation method: Add DOPO-modified phenolic epoxy resin, bisphenol A epoxy resin and an inert organic solvent into a four-necked flask, heat up to 100-110 °C, wait until the materials are completely dissolved, add an organic base for catalysis, heat up to 125-155 °C and keep warm for 1-2 hours, then an epoxy resin with an epoxy equivalent of 600-1000 is obtained. Cool down to 85-95 °C, add an amine compound containing active hydrogen, after adding, heat up to 100-120 °C and keep warm for 3 hours, then cool down and discharge to obtain the functional modified epoxy component B.

2. The electrodeposition coating for forming a flame-retardant insulating polymer coating according to claim 1, Characterized in that, The amine compound containing active hydrogen is at least one primary secondary amine or a polyamine containing both secondary amine groups and tertiary amine groups or a mixture thereof. The primary secondary amine is an alkylamine, a ketimine, an alkanolamine or a mixture thereof. The alkylamine is diethylamine, methyl isobutylamine or dibutylamine. The ketimine is hydroxymethylethylenediamine ketimine or diethylenetriamine ketimine. The alkanolamine is diethanolamine or N-methylethanolamine. The organic base is selected from triethylamine, N-N dimethylbenzylamine, triethanolamine, dimethylethanolamine, triphenylphosphine or methyldiethanolamine. The inert organic solvent is an alcohol solvent, an alcohol ether solvent, a toluene solvent or a ketone solvent. The alcohol solvent is n-butanol or isobutanol. The alcohol ether solvent is ethylene glycol butyl ether, ethylene glycol hexyl ether or diethylene glycol butyl ether. The toluene solvent is toluene, o-xylene or m-xylene. The ketone solvent is methyl isobutyl ketone; The addition amount of the organic base is 1‰-5‰ of the addition amount of F51 phenolic epoxy resin.

3. The electrodeposition coating for forming a flame-retardant insulating polymer coating according to claim 1, Characterized in that, The amine compound containing active hydrogen is at least one primary amine or a polyamine containing both secondary amine groups and tertiary amine groups or a mixture thereof. The primary amine is an alkylamine, a ketimine, an alkanolamine or a mixture thereof. The alkylamine is diethylamine, methyl isobutylamine or dibutylamine. The ketimine is hydroxymethylethylenediamine ketimine or diethylenetriamine ketimine. The alkanolamine is diethanolamine or N-methylethanolamine. The organic base is triethylamine, N,N-dimethylbenzylamine, triethanolamine, dimethylethanolamine, triphenylphosphine or methyldiethanolamine. The inert organic solvent is an alcohol solvent, an alcohol ether solvent, a toluene solvent or a ketone solvent. The alcohol solvent is n-butanol or isobutanol. The alcohol ether solvent is ethylene glycol monobutyl ether, ethylene glycol monohexyl ether or diethylene glycol monobutyl ether. The toluene solvent is toluene, o-xylene or m-xylene. The ketone solvent is methyl isobutyl ketone; The addition amount of the organic base is 1‰ - 3‰ of the addition amount of the DOPO-modified phenolic epoxy resin.

4. An electrodeposition coating for forming a flame-retardant insulating polymer coating according to claim 1, characterized in that, The fluorinated nano-silica sol includes the following preparation method: Disperse the silica sol aqueous solution and tetraethyl orthosilicate mechanically in deionized water, and dropwise add a polymer dispersant and a fluorosilane. Continuously heat at 50 °C in a water bath for 12 - 24 h, filter by suction and wash with deionized water 3 - 5 times to obtain the fluorinated nano-silica sol.

5. An electrodeposition coating for forming a flame-retardant insulating polymer coating according to claim 4, characterized in that, The fluorinated nano-silica sol includes the following components in parts by weight: 10 - 15 parts of silica sol aqueous solution, 0.3 - 0.6 part of tetraethyl orthosilicate, 80 - 100 parts of deionized water, 0.1 - 0.5 part of polymer dispersant, 0.02 - 0.2 part of lactic acid 0.2 - 0.5 part of fluorosilane; Wherein: The silica sol aqueous solution is obtained by adding nano-silica sol with a particle size of 4 - 10 nm, a solid content of 15%, and a pH value of 8 - 9 to deionized water and adjusting the pH value to 5.5 - 6.5 with lactic acid. The fluorosilane is a fluoroalkylsilane with a carbon chain of 5 - 8. The polymer dispersant is at least one of polyamine salt and polyvinylpyrrolidone.

6. An electrodeposition coating for forming a flame-retardant insulating polymer coating according to claim 1, characterized in that, The fully blocked isocyanate includes the following preparation method: In the case of using organotin as a catalyst, heat the mixture of 4,4'-dicyclohexylmethane diisocyanate and a solvent to 45 - 55 °C under stirring, then dropwise add a blocking agent. After the addition is completed in 1.5 - 2 hours, continue to keep warm for 1.5 - 2 hours to obtain the fully blocked isocyanate.

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