High-performance water-based phenoxy resin coating as well as preparation method and application thereof

Abstract

The invention provides a high-performance water-based phenoxy resin coating as well as a preparation method and application thereof, and belongs to the technical field of coatings in the fields of airplanes, high-speed rails and the like, and the raw materials of the coating comprise a cyclic borate-terminated water-based phenoxy resin dispersion, modified flaky boron nitride, modified hollow ceramic microspheres and the like. The preparation method comprises the following steps: mixing a water-based phenoxy resin dispersion with N-methyl pyrrolidone; adding phenylboronic acid and p-toluenesulfonic acid, and carrying out boric acid esterification reaction; adding triethylamine and deionized water to obtain a cyclic borate-terminated aqueous phenoxy resin dispersion; mixing a defoaming agent, rutile type titanium dioxide, modified flaky boron nitride and the like; and adding the cyclic borate-terminated waterborne phenoxy resin dispersion into a stirring kettle, adding modified hollow ceramic microspheres, a pre-dispersed mixed material and the like, and uniformly stirring to obtain the high-performance waterborne phenoxy resin coating. After being cured, the coating disclosed by the invention is good in insulativity, excellent in heat resistance and high in cycle resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings for aircraft, high-speed railways and the like, and in particular to a high-performance water-based phenoxy resin coating and a preparation method and application thereof. Background Art

[0002] Phenoxy resin is a high-performance polymer with ether bonds and hydroxyl groups in its molecular chain. It possesses inherently high electrical insulation and excellent thermal insulation properties (thermal conductivity 0.2-0.3 W / m·K). It is widely used in extreme environment protection applications such as new energy battery packs, ship ballast tanks, and 5G electronic packaging. Phenoxy resin is widely used in electronic and electrical insulation. It can be used as a substrate for copper-clad laminates, replacing epoxy resin as an adhesive layer for high-frequency circuit boards. It can be used in coil encapsulation adhesives for motor / transformer winding encapsulation, with a breakdown voltage of >35kV / mm (IEC 60243 standard). It can also be used as an insulating coating for lithium batteries, such as on aluminum battery cases and tabs.

[0003] The current mainstream water-based processes for phenoxy resins include:

[0004] External emulsification method: dissolve phenoxy resin in butanone, add sodium dodecyl sulfate (SDS) emulsifier, add water to invert the phase after high-speed shearing, and distill to remove the solvent;

[0005] Self-emulsification method: react phenoxy resin with succinic anhydride to graft carboxyl groups, neutralize with ammonia water and then disperse in water.

[0006] The above techniques have fundamental flaws:

[0007] Insulation collapse: Emulsifier residue forms ion channels, and the volume resistivity drops sharply;

[0008] Thermal insulation deteriorates: Hydrophilic groups destroy the conjugated structure of the benzene ring, causing thermal conductivity to soar 80% to 0.45 W / m·K, resulting in a temperature difference of 12°C in the battery pack (far exceeding the safety threshold of 5°C).

[0009] Adhesion decreases: carboxyl groups neutralize and consume cross-linking sites, and metal adhesion decreases from >15 MPa to <8 MPa.

[0010] The phenoxy resins prepared in the prior art often have poor resistance to cold and hot cycles, and poor electrical and thermal insulation properties. Summary of the Invention

[0011] The present invention provides a high-performance water-based phenoxy resin coating, a preparation method and application thereof, in order to solve the technical problems in the prior art of poor resistance to cold and heat cycles, and poor insulation and heat insulating properties of phenoxy resin.

[0012] To achieve the above-mentioned purpose, the present invention provides the following technical solutions:

[0013] A high-performance water-based phenoxy resin coating, the raw materials of which include a cyclic borate-terminated water-based phenoxy resin dispersion, modified flake boron nitride, modified hollow ceramic microspheres, blocked hexamethylene diisocyanate trimer, rutile titanium dioxide, a dispersant, a defoamer, a rheological agent, and an adhesion promoter.

[0014] Preferably, the raw materials include, by mass, 40-60 parts of cyclic borate-terminated aqueous phenoxy resin dispersion, 15-20 parts of modified flake boron nitride, 10-15 parts of titanate-modified hollow ceramic microspheres, 8-10 parts of blocked hexamethylene diisocyanate trimer, 5-8 parts of rutile titanium dioxide, 0.8-1.2 parts of dispersant, 0.3-0.5 parts of defoaming agent, 0.5-1 parts of rheological agent and 0.5-1.5 parts of adhesion promoter.

[0015] Preferably, the modified hollow ceramic microspheres are titanate-modified hollow ceramic microspheres.

[0016] Preferably, the dispersant is a polycarboxylate sodium salt dispersant, the defoamer is a mineral oil-based defoamer, the rheological agent is a hydrophobically modified polyurethane rheological agent, and the adhesion promoter is γ-glycidyloxypropyl silane.

[0017] A method for preparing a high-performance water-based phenoxy resin coating according to the present invention comprises the following steps:

[0018] S1, mixing the aqueous phenoxy resin dispersion with N-methylpyrrolidone, heating, vacuuming, and dehydrating;

[0019] S2, adding phenylboronic acid and p-toluenesulfonic acid, raising the temperature, and reacting;

[0020] S3. After the reaction is completed, the temperature is lowered, triethylamine is added, and then deionized water is added, and the mixture is dispersed in a high-speed disperser to obtain a cyclic borate-terminated water-based phenoxy resin dispersion;

[0021] S4, mixing the hollow ceramic microspheres with titanate, and drying to obtain modified hollow ceramic microspheres;

[0022] S5. Mixing deionized water, a dispersant, a defoamer, rutile titanium dioxide, and modified flake boron nitride to obtain a pre-dispersed mixed material;

[0023] S6. Add the cyclic borate-terminated waterborne phenoxy resin dispersion to a stirred tank, start stirring, and sequentially add the modified hollow ceramic microspheres, pre-dispersed mixed material, rheological agent, and adhesion promoter;

[0024] S7, increase the stirring speed, continue to disperse, and disperse homogenize at high speed;

[0025] S8. Add blocked hexamethylene diisocyanate trimer and stir to obtain a high-performance water-based phenoxy resin coating.

[0026] Preferably, the preparation method comprises:

[0027] S1. Mix the aqueous phenoxy resin dispersion with N-methylpyrrolidone, raise the temperature to 80-85°C, evacuate the reaction system to a vacuum degree of -0.085 MPa, and dehydrate.

[0028] S2, add phenylboronic acid and p-toluenesulfonic acid, introduce nitrogen, and increase the temperature to carry out borate esterification reaction; S3, after the reaction is completed, cool to 60-65 ° C, add triethylamine to neutralize the acid, add deionized water to slow

[0029] The mixture was slowly added dropwise and switched to a high-speed disperser, and a cyclic borate-terminated water-based phenoxy resin dispersion was obtained after emulsification;

[0030] S4, mixing the hollow ceramic microspheres with titanate at a high speed of 1500-2000 rpm for 20-30 min, and obtaining modified hollow ceramic microspheres after drying;

[0031] S5. Mixing deionized water, a dispersant, a defoamer, rutile titanium dioxide, and modified flake boron nitride to obtain a pre-dispersed mixed material;

[0032] S6, adding the cyclic borate-terminated aqueous phenoxy resin dispersion to a stirred tank, starting medium-speed stirring, and sequentially adding the modified hollow ceramic microspheres, pre-dispersed mixed material, rheological agent, and adhesion promoter;

[0033] S7. Increase the stirring speed to 1200-1500 rpm and continue dispersing for 20-30 minutes to achieve high-speed dispersion and homogenization;

[0034] S8. Add blocked hexamethylene diisocyanate trimer and stir evenly to obtain the high-performance water-based phenoxy resin coating.

[0035] Preferably, the preparation method of the modified flake boron nitride comprises the following steps:

[0036] (1) Plasma treatment of boron nitride flakes using an argon plasma processor;

[0037] (2) Plasma-treated boron nitride flakes were placed in a 3-5% KH-560 epoxysilane ethanol solution at a feed ratio of 1 g: 25-30 ml, ultrasonicated, centrifuged, washed with ethanol, and dried to obtain monosilane-modified boron nitride flakes;

[0038] (3) The monosilane-modified flake boron nitride was placed in a 1.5% mass concentration of tridecafluorooctyltriethoxysilane ethanol solution at a feed ratio of 1 g: 15-20 ml, immersed, centrifuged, and dried to obtain the disilane-modified flake boron nitride;

[0039] (4) placing the disilane-modified flake boron nitride in anhydrous ethanol, wherein the mass ratio of the disilane-modified flake boron nitride to anhydrous ethanol is 100:74-78;

[0040] (5) adding ethyl orthosilicate and dropping an aqueous ammonia solution with a mass concentration of 8-9%, wherein the mass ratio of the disilane-modified flaky boron nitride, ethyl orthosilicate, and the aqueous ammonia solution is 100:21-23:3.6-4, reacting, centrifuging, washing, and drying to obtain the modified flaky boron nitride.

[0041] Preferably, the solid content of the aqueous phenoxy resin dispersion in S1 is 38-40%, and the mass ratio of the aqueous phenoxy resin dispersion to N-methylpyrrolidone is 100:75-83.

[0042] Preferably, the mass ratio of the aqueous phenoxy resin dispersion, phenylboric acid, p-toluenesulfonic acid and triethylamine is 1000:48-52:1.25-1.35:0.75-0.85, and the mass ratio of deionized water to aqueous phenoxy resin dispersion in S3 is 11-12:10.

[0043] Preferably, S4 is specifically mixing the hollow ceramic microspheres and NDZ-201 titanate at a high speed of 1500-2000 rpm for 20-30 min, and drying at 110-120° C. for 2-3 h to obtain modified hollow ceramic microspheres, wherein the mass of NDZ-201 titanate is 2-3 wt % of the hollow ceramic microspheres.

[0044] The invention discloses an application of the high-performance water-based phenoxy resin coating in the field of insulating coatings.

[0045] The benzene rings in the phenoxy resin backbone of this invention form a large π-conjugated system, resulting in a highly delocalized electron cloud that hinders free electron migration. This results in low molecular segment polarity and reduces polarization losses under alternating electric fields. The introduction of a cyclic borate endcapping agent with a high BO bond energy (536 kJ / mol) inhibits the ionization of the resin's terminal hydroxyl groups and reduces ionic conductivity, thereby enhancing the insulating properties of the phenoxy resin coating. Furthermore, the cyclic structure reduces free charge at the molecular chain ends, increasing volume resistivity.

[0046] The synergistic effect of modified boron nitride (BN) flakes, modified hollow ceramic microspheres (HCM), and rutile titanium dioxide (TiO2) significantly enhances the coating's electrical and thermal insulation properties through a multi-stage defense mechanism: electron blocking, phonon regulation, and radiation shielding. The wide bandgap of the h-BN flakes blocks electron migration, while the disilane / SiO2 coating increases interfacial resistance, creating a "maze effect" and extending the breakdown path. The Al2O3 / SiO2 shells of the modified hollow ceramic microspheres have high resistivity, while the hollow structure physically isolates the conductive network, forming "insulating islands." The microspheres are embedded between the BN flakes, blocking electron tunneling and enhancing the breakdown field strength. Rutile titanium dioxide reduces carrier concentration, while TiO2 nanoparticles fill the gaps between the BN and microspheres, eliminating localized discharge points. Electron migration path: resin matrix → impact on BN layer (deflection) → blocked by ceramic microspheres → TiO2 fills the gap (insulation is improved), thereby improving the insulation of the matrix.

[0047] Modified hollow ceramic microspheres can block gas-phase conduction, modified boron nitride flakes and TiO2 scatter phonons to regulate solid-phase thermal conduction, and rutile titanium dioxide achieves radiative heat reflection. The oriented skeleton support of BN—horizontally arranged BN flakes—constructs a thermal network that converts normal heat flow into in-plane diffusion, providing dispersed anchor points for the HCM, allowing it to evenly embed between BN layers to form a thermal resistance unit. The HCM's gas-phase synergistic blocking—the microsphere air chamber blocks normal heat conduction. Simultaneously, its titanate-modified shell and the BN SiO2 coating are bonded via BO-Ti, forming a phonon scattering resonance at the interface (thermal resistance superposition >200%). TiO2's radiation-gap filling—nano-TiO2 filling the BN / HCM gap eliminates air thermal bridges and reflects infrared radiation escaping the BN layer. The reflected light path is orthogonal to the in-plane thermal conduction direction of the BN, forming a closed loop of "radiation reflection-lateral thermal conduction," reducing heat loss. The three achieve cascade synergy of gas phase barrier, solid phase regulation and radiation defense through chemical bonding interface and spatial interlocking structure, thereby improving the thermal insulation effect.

[0048] Modified flake boron nitride enhances surface activity through plasma activation, gradient silane-fluorosilane grafting to create a hydrophobic-epoxy dual-functional layer, and nano-SiO2 hybrid coating to form an ion barrier, resulting in a "core-shell-brush" structure (BN@SiO2@fluorosilane). Fluorosilane C-F bonds in the water-based phenoxy resin coating form high-barrier electron traps, significantly increasing volume resistivity. The horizontally oriented BN and SiO2 coating synergistically block the heat conduction path, reducing thermal conductivity and effectively preventing the spread of thermal runaway.

[0049] The technical solution of the present invention has at least the following beneficial effects compared with the prior art:

[0050] The water-based phenoxy resin coating of the present invention blocks electron migration through the large π conjugated system of the phenoxy resin main chain, and combines cyclic borate end-capping to inhibit ion ionization, thereby fundamentally improving the insulation of the substrate; the wide band gap and maze effect of modified boron nitride, the "insulating island" structure of hollow ceramic microspheres, and the carrier elimination ability of titanium dioxide work synergistically to form a multi-level electron blocking network, greatly extending the breakdown path and achieving a leapfrog improvement in insulation performance.

[0051] Horizontally oriented boron nitride flakes convert normal heat flow into lateral diffusion. The vapor phase barrier and phonon scattering resonance of the hollow ceramic microspheres significantly inhibit heat conduction. Rutile titanium dioxide, with its high reflectivity, shields radiant heat and fills thermal bridge gaps. Through chemical bonding and spatial interlocking, these three elements form a synergistic defense system of "solid-phase regulation, vapor phase blocking, and radiation reflection," surpassing the performance limits of traditional thermal insulation materials.

[0052] The fluorosilane hydrophobic layer and the silica corrosion-resistant shell form a molecular-level barrier, effectively resisting moisture, heat, acid corrosion and high-temperature aging; the stable interface and chemical bonding design of the modified filler ensure that the coating maintains its insulation and heat-insulating functions for a long time under harsh conditions such as electrolyte corrosion and salt spray, extending its service life by orders of magnitude. DETAILED DESCRIPTION

[0053] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the following will be described clearly and completely in conjunction with the technical solutions of the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] The mineral oil-based defoamer is BYK-020 from BYK Chemicals;

[0055] The polycarboxylate sodium salt dispersant is the high-efficiency dispersant HT-5040 produced by Nantong Hantai Chemical Co., Ltd.

[0056] The hydrophobically modified polyurethane rheological agent is the polyurethane thickening rheological agent BLJ-6020 produced by Shanghai Baolijia Chemical Co., Ltd.

[0057] γ-Glycidyloxypropylsilane was produced by Guangzhou Yuanda New Materials Co., Ltd., CAS: 2530-83-8;

[0058] The molecular weight of the waterborne phenoxy resin dispersion is 30,000;

[0059] Blocked hexamethylene diisocyanate trimer is Wanhua Chemical (Yantai) product number: Wannate HB-100B.

[0060] Example 1

[0061] A high-performance water-based phenoxy resin coating comprises, by weight, 40 parts of a cyclic borate-terminated water-based phenoxy resin dispersion, 15 parts of modified flaky boron nitride, 10 parts of titanate-modified hollow ceramic microspheres, 8 parts of blocked hexamethylene diisocyanate trimer, 5 parts of rutile titanium dioxide, 0.8 parts of a sodium polycarboxylate dispersant, 0.3 parts of a mineral oil-based defoamer, 0.5 parts of a hydrophobically modified polyurethane rheology agent, and 0.5 parts of γ-glycidyloxypropylsilane.

[0062] A method for preparing the high-performance water-based phenoxy resin coating according to this embodiment comprises the following steps:

[0063] S1, after mixing 1000g of water-based phenoxy resin dispersion and 750g of N-methylpyrrolidone, the temperature was raised to 80°C, and the solid content of the water-based phenoxy resin dispersion was 38%. The reaction system was evacuated.

[0064] The vacuum degree is -0.085MPa, and dehydration is carried out for 30min;

[0065] S2. Add 48 g of phenylboronic acid and 1.25 g of p-toluenesulfonic acid, introduce nitrogen (1.5 L / min), and raise the temperature to carry out borate esterification reaction (110°C). Take samples every hour and measure the hydroxyl value by titration. When the hydroxyl value is 8 mgKOH / g, terminate the reaction.

[0066] S3. After the reaction is completed, the temperature is lowered to 60°C, 0.75 g of triethylamine is added to neutralize the acidity, and 1100 g of deionized water is slowly added dropwise (temperature control = 60°C) into a high-speed disperser. The mixture is emulsified for 30 minutes at a speed of 8000 rpm to obtain a cyclic borate-terminated water-based phenoxy resin dispersion.

[0067] S4, mixing the hollow ceramic microspheres and NDZ-201 titanate at a high speed of 1500 rpm for 30 min, and drying at 110° C. for 2 h to obtain modified hollow ceramic microspheres, wherein the mass of NDZ-201 titanate is 2 wt % of the hollow ceramic microspheres;

[0068] S5. Deionized water (added in an amount of 35% of the total mass of rutile titanium dioxide and modified flaky boron nitride), a sodium polycarboxylate dispersant, a mineral oil-based defoamer, rutile titanium dioxide, and modified flaky boron nitride were mixed, and a high-speed disperser was turned on. The mixture was pre-dispersed at 1000 rpm for 10 minutes to obtain a pre-dispersed mixed material.

[0069] S6. Add the cyclic borate-terminated aqueous phenoxy resin dispersion to a stirred tank, start medium-speed stirring (400 rpm), and sequentially add the modified hollow ceramic microspheres, pre-dispersed mixed material, rheological agent (hydrophobically modified polyurethane rheological agent), and adhesion promoter (γ-glycidyloxypropyl silane);

[0070] S7. Increase the stirring speed to 1200 rpm and continue dispersing for 20 minutes to achieve high-speed dispersion and homogenization;

[0071] S8. Add blocked hexamethylene diisocyanate trimer and stir evenly to obtain the high-performance water-based phenoxy resin coating.

[0072] The preparation method of the modified flaky boron nitride comprises the following steps:

[0073] (1) Plasma treatment of boron nitride flakes was performed using an argon plasma processor with a power of 10W / cm 2 Pass through the treatment area at a speed of 0.5 m / min (exposure 120 s);

[0074] (2) Plasma-treated boron nitride flakes were placed in a 3% KH-560 epoxysilane anhydrous ethanol solution at a feed ratio of 1 g:25 ml, ultrasonicated at 60 °C for 30 min, centrifuged, washed with ethanol, and dried to obtain monosilane-modified boron nitride flakes;

[0075] (3) The monosilane-modified flake boron nitride was placed in an anhydrous ethanol solution of tridecafluorooctyltriethoxysilane with a mass concentration of 1.5% at a feed ratio of 1 g:15 ml, immersed for 2 h, and centrifuged and dried to obtain a disilane-modified flake boron nitride;

[0076] (4) placing the disilane-modified flake boron nitride into anhydrous ethanol, wherein the mass ratio of the disilane-modified flake boron nitride to anhydrous ethanol is 100:74;

[0077] (5) Adding tetraethyl orthosilicate, and then dropping an aqueous ammonia solution with a mass concentration of 8% (1 mL / min), the mass ratio of disilane-modified flake boron nitride, tetraethyl orthosilicate, and aqueous ammonia solution is 100:21:3.6, reacting at 50°C for 4 hours, and obtaining the modified flake boron nitride after centrifugation, washing, and drying.

[0078] Example 2

[0079] A high-performance water-based phenoxy resin coating comprises, by weight, 50 parts of a cyclic borate-terminated water-based phenoxy resin dispersion, 18 parts of modified flaky boron nitride, 13 parts of titanate-modified hollow ceramic microspheres, 9 parts of blocked hexamethylene diisocyanate trimer, 7 parts of rutile titanium dioxide, 1 part of a polycarboxylate sodium salt dispersant, 0.4 parts of a mineral oil-based defoamer, 0.7 parts of a hydrophobically modified polyurethane rheological agent, and 1 part of γ-glycidyloxypropylsilane.

[0080] A method for preparing a high-performance water-based phenoxy resin coating according to this embodiment comprises the following steps:

[0081] S1, after mixing 1000g of an aqueous phenoxy resin dispersion and 800g of N-methylpyrrolidone, the mixture was heated to 83°C, wherein the solid content of the aqueous phenoxy resin dispersion was 39%, and the reaction system was evacuated to a vacuum degree of -0.083, and dehydrated for 40min;

[0082] S2. Add 50 g of phenylboronic acid and 1.3 g of p-toluenesulfonic acid, introduce nitrogen (1.5 L / min), and raise the temperature to carry out borate esterification reaction (110°C). Take samples every hour and measure the hydroxyl value by titration. When the hydroxyl value is 8 mgKOH / g, terminate the reaction.

[0083] S3. After the reaction is completed, the temperature is lowered to 63°C, 0.8 g of triethylamine is added to neutralize the acidity, and 1180 g of deionized water is slowly added dropwise (temperature control = 60°C) into a high-speed disperser. The mixture is emulsified for 30 minutes at a speed of 8000 rpm to obtain a cyclic borate-terminated water-based phenoxy resin dispersion.

[0084] S4, mixing the hollow ceramic microspheres and NDZ-201 titanate at a high speed of 1800 rpm for 25 min, and drying at 115° C. for 2.5 h to obtain modified hollow ceramic microspheres, wherein the mass of NDZ-201 titanate is 2.5 wt % of the hollow ceramic microspheres;

[0085] S5. Deionized water (added in an amount of 35% of the total mass of rutile titanium dioxide and modified flaky boron nitride), a sodium polycarboxylate dispersant, a mineral oil-based defoamer, rutile titanium dioxide, and modified flaky boron nitride were mixed, and a high-speed disperser was turned on. The mixture was pre-dispersed at 1800 rpm for 13 minutes to obtain a pre-dispersed mixed material.

[0086] S6. Add the cyclic borate-terminated aqueous phenoxy resin dispersion to a stirred tank, start medium-speed stirring (500 rpm), and sequentially add the modified hollow ceramic microspheres, pre-dispersed mixed material, rheological agent (hydrophobically modified polyurethane rheological agent), and adhesion promoter (γ-glycidyloxypropyl silane);

[0087] S7, increase the stirring speed to 1400 rpm, continue dispersing for 25 minutes, and disperse and homogenize at high speed;

[0088] S8. Add blocked hexamethylene diisocyanate trimer and stir evenly to obtain the high-performance water-based phenoxy resin coating.

[0089] The preparation method of the modified flaky boron nitride comprises the following steps:

[0090] (1) Plasma treatment of boron nitride flakes was performed using an argon plasma processor with a power of 10 W / cm2 and a speed of 0.5 m / min through the treatment area (exposure 120 s);

[0091] (2) Plasma-treated boron nitride flakes were placed in a 4% KH-560 epoxysilane anhydrous ethanol solution at a feed ratio of 1 g:28 ml, ultrasonicated at 60 °C for 35 min, centrifuged, washed with ethanol, and dried to obtain monosilane-modified boron nitride flakes.

[0092] (3) The monosilane-modified flake boron nitride was placed in an anhydrous ethanol solution of tridecafluorooctyltriethoxysilane with a mass concentration of 1.5% at a feed ratio of 1 g:18 ml, immersed for 3 h, and centrifuged and dried to obtain a disilane-modified flake boron nitride;

[0093] (4) placing the disilane-modified flake boron nitride into anhydrous ethanol, wherein the mass ratio of the disilane-modified flake boron nitride to anhydrous ethanol is 100:76;

[0094] (5) Adding tetraethyl orthosilicate, and then dropping an ammonia solution with a mass concentration of 8.5% (1 mL / min), the mass ratio of disilane-modified flake boron nitride, tetraethyl orthosilicate, and ammonia solution is 100:22:3.8, reacting at 55°C for 4.5 hours, and obtaining the modified flake boron nitride after centrifugation, washing, and drying.

[0095] Example 3

[0096] A high-performance water-based phenoxy resin coating comprises, by weight, 60 parts of a cyclic borate-terminated water-based phenoxy resin dispersion, 20 parts of modified flaky boron nitride, 15 parts of titanate-modified hollow ceramic microspheres, 10 parts of blocked hexamethylene diisocyanate trimer, 8 parts of rutile titanium dioxide, 1.2 parts of a polycarboxylate sodium salt dispersant, 0.5 parts of a mineral oil-based defoamer, 1 part of a hydrophobically modified polyurethane rheological agent, and 1.5 parts of γ-glycidyloxypropylsilane.

[0097] A method for preparing a high-performance water-based phenoxy resin coating according to this embodiment comprises the following steps:

[0098] S1, after mixing 1000g of an aqueous phenoxy resin dispersion and 830g of N-methylpyrrolidone, the temperature was raised to 85°C, wherein the solid content of the aqueous phenoxy resin dispersion was 40%, and the reaction system was evacuated to a vacuum degree of -0.080MPa, and dehydrated for 40min;

[0099] S2. Add 52 g of phenylboronic acid and 1.35 g of p-toluenesulfonic acid, introduce nitrogen (1.5 L / min), and raise the temperature to carry out borate esterification reaction (110°C). Take samples every hour and measure the hydroxyl value by titration. Terminate the reaction when the hydroxyl value is 8 mgKOH / g.

[0100] S3. After the reaction is completed, the temperature is lowered to 65°C, 0.85 g of triethylamine is added to neutralize the acidity, and 1200 g of deionized water is slowly added dropwise (temperature control = 50°C) into a high-speed disperser. The mixture is emulsified for 30 minutes at a speed of 8000 rpm to obtain a cyclic borate-terminated water-based phenoxy resin dispersion.

[0101] S4, mixing the hollow ceramic microspheres and NDZ-201 titanate at 2000 rpm for 20 min, and drying at 120° C. for 3 h to obtain modified hollow ceramic microspheres, wherein the mass of NDZ-201 titanate is 3 wt % of the hollow ceramic microspheres;

[0102] S5. Deionized water (added in an amount of 35% of the total mass of rutile titanium dioxide and modified flaky boron nitride), a sodium polycarboxylate dispersant, a mineral oil-based defoamer, rutile titanium dioxide, and modified flaky boron nitride were mixed, and a high-speed disperser was turned on. The mixture was pre-dispersed at 1500 rpm for 15 minutes to obtain a pre-dispersed mixed material.

[0103] S6. Add the cyclic borate-terminated aqueous phenoxy resin dispersion to a stirred tank, start medium-speed stirring (600 rpm), and sequentially add the modified hollow ceramic microspheres, pre-dispersed mixed material, rheological agent (hydrophobically modified polyurethane rheological agent), and adhesion promoter (γ-glycidyloxypropyl silane);

[0104] S7, increase the stirring speed to 1500 rpm, continue dispersing for 30 minutes, and disperse and homogenize at high speed;

[0105] S8. Add blocked hexamethylene diisocyanate trimer and stir evenly to obtain the high-performance water-based phenoxy resin coating.

[0106] The preparation method of the modified flaky boron nitride comprises the following steps:

[0107] (1) Plasma treatment of boron nitride flakes was performed using an argon plasma processor with a power of 10W / cm 2 Pass through the treatment area at a speed of 0.5 m / min (exposure 120 s);

[0108] (2) Plasma-treated boron nitride flakes were placed in a 5% KH-560 epoxysilane anhydrous ethanol solution at a feed ratio of 1 g:30 ml, ultrasonicated at 60 °C for 40 min, centrifuged, and washed with ethanol / dried to obtain monosilane-modified boron nitride flakes;

[0109] (3) The monosilane-modified flake boron nitride was placed in an anhydrous ethanol solution of tridecafluorooctyltriethoxysilane with a mass concentration of 1.5% at a feed ratio of 1 g:20 ml, immersed for 4 hours, and centrifuged and dried to obtain a disilane-modified flake boron nitride;

[0110] (4) placing the disilane-modified flake boron nitride into anhydrous ethanol, wherein the mass ratio of the disilane-modified flake boron nitride to anhydrous ethanol is 100:78;

[0111] (5) Adding tetraethyl orthosilicate, and then dropping an aqueous ammonia solution with a mass concentration of 9% (1 mL / min), the mass ratio of disilane-modified flake boron nitride, tetraethyl orthosilicate, and aqueous ammonia solution is 100:23:4, reacting at 60°C for 5 hours, and obtaining the modified flake boron nitride after centrifugation, washing, and drying.

[0112] Comparative Example 1

[0113] This comparative example is the same as Example 1, except that steps (4) and (5) are not included in the preparation process of the modified flake boron nitride in this comparative example, and the modified flake boron nitride in this comparative example is disilane-modified flake boron nitride.

[0114] Comparative Example 2

[0115] This comparative example is the same as Example 1, except that in this comparative example, an equal amount of modified flake boron nitride is replaced by titanate-modified hollow ceramic microspheres.

[0116] Comparative Example 3

[0117] This comparative example is the same as Example 1, except that the modified flake boron nitride in this comparative example is 10 parts of modified flake boron nitride.

[0118] Comparative Example 4

[0119] This comparative example is the same as Example 1, except that the modified flake boron nitride in this comparative example is 25 parts of modified flake boron nitride.

[0120] The high-performance water-based phenoxy resin coatings of Examples 1-3 and Comparative Examples 1-4 were cured at 120° C. for 30 minutes and then subjected to relevant tests.

[0121] The reference test standard for volume resistivity test is GB / T 1410-2006. The test results are shown in Table 1 below.

[0122] Table 1 Volume resistivity of each group of waterborne phenoxy resin coatings

[0123] Group Model 1 / Ω·cm Model 2 / Ω·cm Model 3 / Ω·cm Average volume resistivity / Ω·cm Example 1 <![CDATA[3.46×10 15 ]]> <![CDATA[3.42×10 15 ]]> <![CDATA[3.4×10 15 ]]> <![CDATA[3.43×10 15 ]]> Example 2 <![CDATA[3.54×10 15 ]]> <![CDATA[3.53×10 15 ]]> <![CDATA[3.58×10 15 ]]> <![CDATA[3.55×10 15 ]]> Example 3 <![CDATA[3.46×10 15 ]]> <![CDATA[3.41×10 15 ]]> <![CDATA[3.4×10 15 ]]> <![CDATA[3.42×10 15 ]]> Comparative Example 1 <![CDATA[3.16×10 15 ]]> <![CDATA[3.18×10 15 ]]> <![CDATA[3.18×10 15 ]]> <![CDATA[3.17×10 15 ]]> Comparative Example 2 <![CDATA[2.65×10 15 ]]> <![CDATA[2.66×10 15 ]]> <![CDATA[2.64×10 15 ]]> <![CDATA[2.65×10 15 ]]> Comparative Example 3 <![CDATA[31.10 ×10 15 ]]> <![CDATA[31.10 ×10 15 ]]> <![CDATA[31.04 ×10 15 ]]> <![CDATA[31.08 ×10 15 ]]> Comparative Example 4 <![CDATA[32.09 ×10 15 ]]> <![CDATA[32.14 ×10 15 ]]> <![CDATA[32.19 ×10 15 ]]> <![CDATA[32.14 ×10 15 ]]>

[0124] The thermal conductivity test reference standard is GB / T 10297-2015, and the test results are shown in Table 2 below.

[0125] Table 2 Thermal conductivity of each group of water-based phenoxy resin coatings

[0126] Group Style 1 / W / (m·k) Style 2 / W / (m·k) Style 3 / W / (m·k) Average volume resistivity / W / (m·k) Example 1 0.0783 0.0782 0.078 0.0782 Example 2 0.0783 0.079 0.0783 0.0785 Example 3 0.0793 0.0796 0.0796 0.0795 Comparative Example 1 0.0943 0.0942 0.0947 0.0944 Comparative Example 2 0.1251 0.1297 0.1289 0.1279 Comparative Example 3 0.0821 0.0824 0.0821 0.0822 Comparative Example 4 0.0909 0.0907 0.0914 0.0910

[0127] The adhesion (cross-hatch method) test refers to the test standard GB / T 9286-1998. The test results are shown in Table 3 below.

[0128] Table 3 Adhesion of each group of water-based phenoxy resin coatings

[0129] Group Style 1 Style 2 Style 3 Example 1 Level 0 Level 0 Level 0 Example 2 Level 0 Level 0 Level 0 Example 3 Level 0 Level 0 Level 0 Comparative Example 1 Level 0 Level 0 Level 0 Comparative Example 2 Level 0 Level 0 Level 1

[0130] The reference test standard for the thermal cycling resistance test (-40~120℃) is GB / T 1735-2009. The test results are shown in Table 4 below.

[0131] Table 4 Resistance to cold and hot cycling of each group of water-based phenoxy resin coatings

[0132] Group Style 1 Style 2 Style 3 Example 1 20 times without cracking 20 times without cracking 20 times without cracking Example 2 20 times without cracking 19 times without cracking 20 times without cracking Example 3 20 times without cracking 20 times without cracking 20 times without cracking Comparative Example 1 20 times without cracking 19 times there was cracking 19 times there was cracking Comparative Example 2 16 times cracked 15 times there was cracking 16 times cracked

[0133] It can be seen from the test data in Tables 1 to 4 that the water-based phenoxy resin coating of the present invention has good electrical insulation and heat insulation properties.

[0134] Comparing the test data in Example 1 and Comparative Example 1, it can be seen that the bis-silane-modified flake boron nitride without the synergistic modification of ethanol and ethyl orthosilicate will reduce the thermal insulation and electrical insulation properties of the coating. This is because the bis-silane-modified flake boron nitride without the synergistic modification of ethanol and ethyl orthosilicate has only the surface modified by bis-silane (KH-560 The modified boron nitride (BN) is modified with tridecafluorooctyltriethoxysilane (T3F3) and lacks a silica (SiO2) coating formed by the hydrolysis of ethyl orthosilicate, leading to the following problems: On the one hand, the interfacial bonding between the flake boron nitride and the resin matrix is ​​weak, easily forming interfacial defects (such as voids and bubbles). These defects become channels for heat conduction and charge leakage, reducing thermal insulation and electrical insulation. On the other hand, due to the lack of the barrier effect of the SiO2 coating, the double silane modified layer may hydrolyze and fall off due to environmental factors (such as humidity and temperature) during the preparation or use of the coating, resulting in a decrease in the dispersion of the BN flakes and stacking and agglomeration, making it impossible to form a continuous and stable thermal insulation and electrical insulation network, thereby significantly weakening the thermal insulation (increased thermal conductivity) and electrical insulation properties (decreased volume resistivity and breakdown voltage) of the coating. Comparing the test data in Example 1 and Comparative Example 2, it can be seen that the thermal insulation, electrical insulation, and resistance to cold and hot cycling of the coating without the modified BN flakes are all affected.

[0135] By observing Table 1 and Table 2, and comparing the test data in Example 1 and Comparative Examples 3 and 4, it can be seen that the addition amount of modified flake boron nitride affects the heat resistance and insulation properties of the coating. This is because the layered structure and excellent intrinsic properties (high thermal conductivity and high insulation) of the modified flake boron nitride require a reasonable addition amount to form an effective functional network: when the addition amount is insufficient, it is difficult for the flakes to construct a continuous heat conduction path and insulation barrier, heat is easily transferred through the resin matrix, and charge is easily leaked at defects, resulting in limited improvement in heat resistance (such as heat deformation temperature, thermal weight loss stability) and insulation properties (volume resistivity, breakdown voltage); and when the addition amount is too high, the flakes are easily agglomerated to form local defects (such as voids and stacking), which destroy the continuity of the resin matrix and increase the heat conduction channel and charge migration path. At the same time, too high a filling amount will reduce the interfacial bonding strength of the coating, resulting in a decrease in both heat resistance and insulation properties.

[0136] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A high-performance water-based phenoxy resin coating, characterized in that: Its raw materials include: cyclic borate-terminated water-based phenoxy resin dispersion, modified flake boron nitride, modified hollow ceramic microspheres, blocked hexamethylene diisocyanate trimer, rutile titanium dioxide, dispersant, defoamer, rheological agent and adhesion promoter.

2. A high-performance water-based phenoxy resin coating according to claim 1, characterized in that: The raw materials include, by mass, 40-60 parts of cyclic borate-terminated water-based phenoxy resin dispersion, 15-20 parts of modified flaky boron nitride, 10-15 parts of modified hollow ceramic microspheres, 8-10 parts of blocked hexamethylene diisocyanate trimer, 5-8 parts of rutile titanium dioxide, 0.8-1.2 parts of dispersant, 0.3-0.5 parts of defoaming agent, 0.5-1 parts of rheological agent and 0.5-1.5 parts of adhesion promoter.

3. A high-performance water-based phenoxy resin coating according to claim 1, characterized in that: The modified hollow ceramic microspheres are titanate-modified hollow ceramic microspheres.

4. A high-performance water-based phenoxy resin coating according to claim 1, characterized in that: The dispersant is a polycarboxylate sodium salt dispersant, the defoamer is a mineral oil-based defoamer, the rheological agent is a hydrophobically modified polyurethane rheological agent, and the adhesion promoter is gamma-glycidyl ether oxypropyl silane.

5. A method for preparing a high-performance water-based phenoxy resin coating according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, mixing the aqueous phenoxy resin dispersion with N-methylpyrrolidone, heating, vacuuming, and dehydrating; S2, adding phenylboronic acid and p-toluenesulfonic acid, raising the temperature, and reacting; S3. After the reaction is completed, the temperature is lowered, triethylamine is added, and then deionized water is added, and the mixture is dispersed in a high-speed disperser to obtain a cyclic borate-terminated water-based phenoxy resin dispersion; S4, mixing the hollow ceramic microspheres with titanate, and drying to obtain modified hollow ceramic microspheres; S5. Mixing deionized water, a dispersant, a defoamer, rutile titanium dioxide, and modified flake boron nitride to obtain a pre-dispersed mixed material; S6. Add the cyclic borate-terminated waterborne phenoxy resin dispersion to a stirred tank, start stirring, and sequentially add the modified hollow ceramic microspheres, pre-dispersed mixed material, rheological agent, and adhesion promoter; S7, increase the stirring speed, continue to disperse, and disperse homogenize at high speed; S8. Add blocked hexamethylene diisocyanate trimer and stir to obtain a high-performance water-based phenoxy resin coating.

6. The method according to claim 5, characterized in that The preparation method of the modified flaky boron nitride comprises the following steps: (1) Plasma treatment of boron nitride flakes using an argon plasma processor; (2) Plasma-treated boron nitride flakes were placed in a 3-5% KH-560 epoxysilane ethanol solution at a feed ratio of 1 g: 25-30 ml, ultrasonicated, centrifuged, washed with ethanol, and dried to obtain monosilane-modified boron nitride flakes; (3) The monosilane-modified flake boron nitride was placed in a 1.5% mass concentration of tridecafluorooctyltriethoxysilane ethanol solution at a feed ratio of 1 g: 15-20 ml, immersed, centrifuged, and dried to obtain the disilane-modified flake boron nitride; (4) placing the disilane-modified flake boron nitride in anhydrous ethanol, wherein the mass ratio of the disilane-modified flake boron nitride to anhydrous ethanol is 100:74-78; (5) adding ethyl orthosilicate and dropping an aqueous ammonia solution with a mass concentration of 8-9%, wherein the mass ratio of the disilane-modified flaky boron nitride, ethyl orthosilicate, and the aqueous ammonia solution is 100:21-23:3.6-4, reacting, centrifuging, washing, and drying to obtain the modified flaky boron nitride.

7. The method according to claim 5, characterized in that The solid content of the aqueous phenoxy resin dispersion in S1 is 38-40%, and the mass ratio of the aqueous phenoxy resin dispersion to N-methylpyrrolidone is 100:75-83.

8. The method according to claim 5, characterized in that The mass ratio of the aqueous phenoxy resin dispersion, phenylboric acid, p-toluenesulfonic acid and triethylamine is 1000:48-52:1.25-1.35:0.75-0.85, and the mass ratio of the deionized water to the aqueous phenoxy resin dispersion in S3 is 11-12:

10.

9. The method according to claim 5, characterized in that S4 specifically comprises mixing the hollow ceramic microspheres and NDZ-201 titanate at a high speed of 1500-2000 rpm for 20-30 min, and drying at 110-120° C. for 2-3 h to obtain modified hollow ceramic microspheres, wherein the mass of NDZ-201 titanate is 2-3 wt % of the hollow ceramic microspheres.

10. Use of the high-performance water-based phenoxy resin coating according to claims 1 to 4 in the field of insulating coatings.