High performance waterborne phenoxy resin coating and its preparation method and application

Abstract

The application provides a high-performance water-based phenoxy resin coating and a preparation method and application thereof, and belongs to the technical field of coatings for airplanes, high-speed rails and the like. Raw materials of the coating include 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 the water-based phenoxy resin dispersion with N-methylpyrrolidone; adding phenyl boronic acid and p-toluenesulfonic acid to perform a borate esterification reaction; adding triethylamine and deionized water to obtain the cyclic borate-terminated water-based phenoxy resin dispersion; mixing defoaming agents, rutile titanium dioxide and modified flaky boron nitride and the like; adding the cyclic borate-terminated water-based phenoxy resin dispersion into a stirring kettle, adding modified hollow ceramic microspheres, pre-dispersed mixed materials and the like, and uniformly stirring to obtain the high-performance water-based phenoxy resin coating. The coating has good insulation, good heat resistance and strong cycle resistance after curing.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coatings for aircraft, high-speed rail, etc., in particular to a high-performance water-based phenoxy resin coating and a preparation method and application thereof. BACKGROUND

[0002] Phenoxy resin is a high-performance polymer containing ether bonds and hydroxyl groups in the molecular chain, with intrinsic high insulation and excellent thermal insulation (thermal conductivity 0.2-0.3 W / m·K), widely used in new energy battery pack, ship ballast tank, 5G electronic packaging and other extreme environment protection fields. Phenoxy resin is widely used in the field of electronic and electrical insulation. It can be used for copper-clad plate substrate, replacing epoxy resin as high-frequency circuit board bonding layer; it can be applied to coil packaging glue, used for motor / transformer winding packaging, breakdown voltage > 35 kV / mm (IEC 60243 standard); it can be applied to lithium battery insulation coating, coated on battery aluminum shell / pole.

[0003] The current mainstream water-based process of phenoxy resin includes:

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

[0005] Self-emulsification method: grafting carboxyl groups to phenoxy resin by reacting with succinic anhydride, and dispersing after neutralization with ammonia water.

[0006] The above-mentioned technologies have the following fundamental defects:

[0007] Insulation collapse: residual emulsifier forms ion channels, and volume resistivity drops sharply;

[0008] Thermal insulation degradation: hydrophilic groups destroy the conjugated structure of benzene ring, thermal conductivity rises by 80% to 0.45 W / m·K, resulting in a battery pack temperature difference of 12℃ (far exceeding the safety threshold of 5℃);

[0009] Adhesion decreases: carboxyl neutralization consumes crosslinking sites, and metal adhesion decreases from > 15 MPa to < 8 MPa.

[0010] The phenoxy resin prepared in the prior art often has poor cold and hot cycle resistance, and poor insulation and thermal insulation. SUMMARY

[0011] The present application provides a high-performance water-based phenoxy resin coating and a preparation method and application thereof, to solve the technical problems of poor cold and hot cycle resistance, poor insulation and thermal insulation of phenoxy resin in the prior art.

[0012] To achieve the above-mentioned application purposes, the technical solutions provided by the present application are as follows:

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

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

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

[0016] Preferably, the dispersant is a sodium salt of polycarboxylic acid dispersant, the defoaming agent is a mineral oil-based defoaming agent, the rheological agent is a hydrophobically modified polyurethane rheological agent, and the adhesion promoter is a gamma-glycidoxypropylsilane.

[0017] A preparation method of the high-performance water-based phenoxy resin coating according to the present application, comprising the following steps:

[0018] S1, mixing the water-based phenoxy resin dispersion with N-methylpyrrolidone, heating, vacuumizing and dehydrating;

[0019] S2, adding phenylboronic acid and p-toluenesulfonic acid, heating and reacting;

[0020] S3, after the reaction is completed, cooling, adding triethylamine, then adding deionized water, and dispersing in a high-speed disperser to obtain the cyclic borate ester-terminated water-based phenoxy resin dispersion;

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

[0022] S5, mixing deionized water, dispersant, defoaming agent, rutile titanium dioxide and modified flaky boron nitride, and obtaining a pre-dispersed mixture after mixing;

[0023] S6, adding the cyclic borate ester-terminated water-based phenoxy resin dispersion into a stirred tank, starting stirring, and sequentially adding the modified hollow ceramic microspheres, the pre-dispersed mixture, the rheological agent and the adhesion promoter;

[0024] S7, increasing the stirring speed, continuously dispersing and high-speed dispersing and homogenizing;

[0025] S8, add a closed hexamethylene diisocyanate trimer, stir to obtain a high-performance water-based phenoxy resin coating.

[0026] Preferably, the preparation method comprises:

[0027] S1, mix the water-based phenoxy resin dispersion with N-methyl pyrrolidone, and then heat to 80-85°C, vacuumize the reaction system to a vacuum degree of -0.085 MPa, and dehydrate;

[0028] S2, add phenylboric acid and p-toluenesulfonic acid, pass nitrogen, and increase the temperature to perform boric acid esterification reaction; S3, after the reaction is completed, cool to 60-65°C, add triethylamine to neutralize the acid, and add deionized water to

[0029] Slowly add a high-speed dispersion machine, emulsify to obtain a cyclic boric acid ester-terminated water-based phenoxy resin dispersion;

[0030] S4, mix the hollow ceramic microspheres with titanate at a high speed of 1500-2000 rpm for 20-30 min, and dry to obtain modified hollow ceramic microspheres;

[0031] S5, mix deionized water, a dispersant, a defoaming agent, rutile titanium dioxide, and modified flaky boron nitride, and mix to obtain a pre-dispersion mixture;

[0032] S6, add the cyclic boric acid ester-terminated water-based phenoxy resin dispersion to a stirred tank, start moderate stirring, and sequentially add the modified hollow ceramic microspheres, the pre-dispersion mixture, a rheological agent, and an adhesion promoter;

[0033] S7, increase the stirring speed to 1200-1500 rpm, and continuously disperse for 20-30 min to homogenize at a high speed;

[0034] S8, add a closed hexamethylene diisocyanate trimer, stir uniformly, and obtain the high-performance water-based phenoxy resin coating.

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

[0036] (1) treat the flaky boron nitride with an argon plasma treater;

[0037] (2) put the flaky boron nitride treated by plasma into a KH-560 epoxy silane ethanol solution with a mass concentration of 3-5% at a feeding ratio of 1 g: 25-30 ml, ultrasonic, centrifuge, wash with ethanol, and dry to obtain a monosilane-modified flaky boron nitride;

[0038] (3) according to the ratio of 1g:15-20ml, the single silane modified boron nitride is put into the 1.5% mass concentration of tridecafluorooctyltriethoxysilane ethanol solution, immersed, centrifuged, dried to obtain the double silane modified boron nitride;

[0039] (4) the double silane modified boron nitride is put into anhydrous ethanol, and the mass ratio of the double silane modified boron nitride to anhydrous ethanol is 100:74-78;

[0040] (5) tetraethyl orthosilicate is added, and the 8-9% mass concentration of ammonia water solution is added dropwise, wherein the mass ratio of the double silane modified boron nitride, tetraethyl orthosilicate and ammonia water solution is 100:21-23:3.6-4, and the modified boron nitride is obtained after reaction, centrifugation, washing and drying.

[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 the deionized water to the aqueous phenoxy resin dispersion in S3 is 11-12:10.

[0043] Preferably, S4 is specifically that the hollow ceramic microspheres and NDZ-201 titanate are mixed at 1500-2000rpm for 20-30min, and the modified hollow ceramic microspheres are obtained after drying at 110-120℃ for 2-3h, and the mass of the NDZ-201 titanate is 2-3wt% of the hollow ceramic microspheres.

[0044] An application of a high-performance aqueous phenoxy resin coating of the application in the field of insulating coatings.

[0045] The benzene rings in the phenoxy resin main chain of the application form a large pi conjugated system, the electron cloud is highly delocalized, the free electron migration is hindered, the molecular chain segment polarity is low, and the polarization loss under the alternating electric field is reduced. The cyclic borate ester end-capping is introduced, the B-O bond energy is high (536 kJ / mol), the resin terminal hydroxyl ionization is inhibited, and the ionic conductivity is reduced. Therefore, the insulating property of the phenoxy resin coating is improved. In addition, the cyclic structure reduces the free charge at the molecular chain end, and the volume resistivity is improved.

[0046] The modified sheet-like boron nitride (BN), the modified hollow ceramic microsphere (HCM) and the rutile titanium dioxide (TiO2) synergistically act together through the multi-level defense mechanism of "electron blocking-phonon regulation-radiation shielding", thereby significantly improving the insulation and thermal insulation of the coating. The h-BN wide band gap of the modified sheet-like boron nitride blocks the electron migration, the double-silane / SiO2 coating layer improves the interface resistance to cause the "labyrinth effect", and the breakdown path is prolonged. The modified hollow ceramic microsphere has a large Al2O3 / SiO2 shell layer resistance, and the hollow structure physically separates the conductive network to form an "insulation island". The microsphere is embedded between the BN layers to block the electron tunneling effect, and the breakdown field strength is improved. The rutile titanium dioxide can reduce the carrier concentration, and the TiO2 nanoparticles fill the gap between the BN-microsphere to eliminate the partial discharge point. The electron migration path is: resin matrix → impact BN sheet layer (deflection) → blocked by ceramic microsphere → TiO2 fills the gap (insulation is improved), thereby realizing the improvement of the insulation of the matrix.

[0047] The modified hollow ceramic microsphere can realize gas phase conduction blocking, the modified sheet-like boron nitride and TiO2 scatter phonons to realize solid phase thermal conduction regulation, and the rutile titanium dioxide realizes radiation heat reflection. The oriented skeleton support of BN supports the horizontally arranged BN layer to construct a heat conduction network, converts the normal heat flow into in-plane diffusion, provides dispersion anchor points for HCM, and makes the HCM uniformly embedded between the BN layers to form a thermal resistance unit. The gas phase synergistic blocking of HCM blocks the normal heat conduction of the gas chamber, and the titanate modified shell and the SiO2 coating layer of BN are bonded through B-O-Ti to form a phonon scattering resonance at the interface (thermal resistance is stacked by more than 200%). The radiation-gap filling of TiO2 fills the gap between BN / HCM with nano-TiO2 to eliminate the air heat bridge, and reflects the infrared radiation overflowing from the BN layer. The reflection light path is orthogonal to the in-plane heat conduction direction of BN, forming a "radiation reflection-lateral heat conduction" closed loop to reduce heat loss. The three realize the cascade synergy of gas phase blocking, solid phase regulation and radiation defense through the bonding interface and space interlocking structure, thereby realizing the improvement of the heat insulation effect.

[0048] The modified sheet-like boron nitride improves the surface activity through plasma activation, constructs a hydrophobic-epoxy bifunctional layer through silane-fluorosilane gradient grafting, and forms an ion barrier through nano-SiO2 hybrid coating to form a "core-shell-brush" structure (BN@SiO2@fluorosilane). In the water-based phenoxy resin coating, the fluorosilane C-F bond forms a high-potential barrier electron trap, and the volume resistivity is greatly improved. The horizontally oriented BN and the SiO2 coating layer synergistically block the heat conduction path, and the thermal conductivity coefficient decreases, effectively blocking the spread of thermal runaway.

[0049] Compared with the prior art, the technical scheme of the present application has at least the following beneficial effects:

[0050] The water-based phenoxy resin coating of the present application fundamentally improves the insulation of the substrate by blocking electron migration through the large pi-conjugated system of the phenoxy resin backbone and inhibiting ionic ionization through cyclic borate end-capping; the wide band gap of modified boron nitride, the labyrinth effect, the "insulating island" structure of hollow ceramic microspheres, and the carrier elimination ability of titanium dioxide synergistically form a multi-level electron barrier network, significantly extending the breakdown path and achieving a leap in insulation performance.

[0051] Horizontally oriented boron nitride layers convert normal heat flow into lateral diffusion, and the gas phase barrier of hollow ceramic microspheres and phonon scattering resonance significantly inhibit heat conduction, while rutile titanium dioxide shields radiant heat through high reflectivity and fills the gap between thermal bridges. The three are chemically bonded and spatially interlocked to build a synergistic defense system of "solid phase regulation-gas phase blocking-radiation reflection", breaking through the performance limits of traditional thermal insulation materials.

[0052] The fluorosilane hydrophobic layer and the corrosion-resistant silica shell form a molecular-level barrier, effectively resisting heat and humidity, acid corrosion, and high-temperature aging; the stable interface and chemical bonding design of the modified filler ensure that the coating maintains insulation and thermal insulation functions under harsh conditions such as electrolyte corrosion and salt spray, with a significant extension of the service life. DETAILED DESCRIPTION

[0053] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical scheme of the embodiments in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the described embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0054] The mineral oil-based defoaming agent is BYK-020 from BYK (Borchem);

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

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

[0057] The gamma-glycidyl ether oxypropyl silane is produced by Guangzhou Yuanda New Materials Co., Ltd., with CAS: 2530-83-8;

[0058] The molecular weight of the water-based phenoxy resin dispersion is 30000;

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

[0060] Embodiment 1

[0061] A high-performance water-based phenoxy resin coating, the raw materials of which include, by mass fraction, 40 parts of a cyclic borate ester-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 polycarboxylic acid sodium salt dispersant, 0.3 parts of mineral oil-based defoaming agent, 0.5 parts of hydrophobically modified polyurethane rheological agent, and 0.5 parts of γ-glycidyl ether oxypropyl silane.

[0062] A preparation method of a high-performance water-based phenoxy resin coating based on the embodiment, comprising the following steps:

[0063] S1, mix 1000 g of water-based phenoxy resin dispersion with 750 g of N-methyl pyrrolidone and heat to 80°C, the solid content of the water-based phenoxy resin dispersion is 38%, vacuumize the reaction system to a vacuum degree of -0.085 MPa and dehydrate for 30 min;

[0064] S2, add 48 g of phenyl boronic acid and 1.25 g of p-toluenesulfonic acid, introduce nitrogen (1.5 L / min), and increase the temperature for borate esterification reaction (110°C); take samples every hour: measure the hydroxyl value by titration, and terminate the reaction when the hydroxyl value = 8 mgKOH / g;

[0065] S3, after the reaction is completed, cool to 60°C, add 0.75 g of triethylamine to neutralize the acidity, slowly add 1100 g of deionized water (temperature control = 60°C) into a high-speed disperser, emulsify for 30 min, the rotation speed during emulsification is 8000 rpm, to obtain a cyclic borate ester-terminated water-based phenoxy resin dispersion;

[0066] S4, mix the hollow ceramic microspheres and NDZ-201 titanate at a high speed of 1500 rpm for 30 min, dry at 110°C for 2 h to obtain modified hollow ceramic microspheres, the mass of NDZ-201 titanate is 2 wt% of the hollow ceramic microspheres;

[0067] S5, mix deionized water (the addition amount is 35% of the total mass of rutile titanium dioxide and modified flaky boron nitride), polycarboxylic acid sodium salt dispersant, mineral oil-based defoaming agent, rutile titanium dioxide, and modified flaky boron nitride, start a high-speed disperser, and pre-disperse at 1000 rpm for 10 min, to obtain a pre-dispersed mixture after mixing;

[0068] S5, mix deionized water (the addition amount is 35% of the total mass of rutile titanium dioxide and modified flaky boron nitride), polycarboxylic acid sodium salt dispersant, mineral oil-based defoaming agent, rutile titanium dioxide, and modified flaky boron nitride, start a high-speed disperser, and pre-disperse at 1000 rpm for 10 min, to obtain a pre-dispersed mixture after mixing;

[0069] S6, the cyclic borate end-capped aqueous phenoxy resin dispersion is added to the stirred tank, medium stirring (400 rpm) is started, the modified hollow ceramic microspheres, the pre-dispersed mixture, the rheological agent (hydrophobically modified polyurethane rheological agent) and the adhesion promoter (γ-glycidoxypropylsilane) are sequentially added;

[0070] S7, the stirring speed is increased to 1200 rpm, and the dispersion is continued for 20 minutes, and high-speed dispersion homogenization is performed;

[0071] S8, the blocked hexamethylene diisocyanate trimer is added, and after uniform stirring, the high-performance aqueous phenoxy resin coating is obtained.

[0072] The preparation method of the modified sheet-shaped boron nitride comprises the following steps:

[0073] (1) The sheet-shaped boron nitride is subjected to plasma treatment by using an argon plasma treater, the power is 10 W / cm 2 at a speed of 0.5 m / min through the treatment zone (exposed for 120 s);

[0074] (2) The sheet-shaped boron nitride subjected to plasma treatment is placed in a 3% KH-560 epoxy silane anhydrous ethanol solution according to a feeding ratio of 1 g:25 ml, ultrasonic treatment is performed at 60°C for 30 min, centrifugal separation is performed, ethanol cleaning and drying are performed, and the monosilane-modified sheet-shaped boron nitride is obtained;

[0075] (3) The monosilane-modified sheet-shaped boron nitride is placed in a 1.5% tridecafluorooctyltriethoxysilane anhydrous ethanol solution according to a feeding ratio of 1 g:15 ml, immersed for 2 h, centrifuged and dried to obtain the disilane-modified sheet-shaped boron nitride;

[0076] (4) The disilane-modified sheet-shaped boron nitride is placed in anhydrous ethanol, and the mass ratio of the disilane-modified sheet-shaped boron nitride to anhydrous ethanol is 100:74;

[0077] (5) Tetraethyl orthosilicate is added, and then an 8% ammonia water solution (1 mL / min) is added dropwise, the mass ratio of the disilane-modified sheet-shaped boron nitride to tetraethyl orthosilicate to the ammonia water solution is 100:21:3.6, 50°C reaction is performed for 4 h, centrifugal separation, washing and drying are performed, and the modified sheet-shaped boron nitride is obtained.

[0078] Example 2

[0079] A high-performance water-based phenoxy resin coating, the raw materials of which include, by mass fraction, 50 parts of 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 polycarboxylic acid sodium salt dispersant, 0.4 parts of mineral oil-based defoaming agent, 0.7 parts of hydrophobically modified polyurethane rheological agent, and 1 part of γ-glycidyl ether oxypropyl silane.

[0080] A preparation method of a high-performance water-based phenoxy resin coating according to the embodiment, comprising the following steps:

[0081] S1, mix 1000g of water-based phenoxy resin dispersion with 800g of N-methyl pyrrolidone and heat to 83℃, the solid content of the water-based phenoxy resin dispersion is 39%, vacuumize the reaction system to a vacuum degree of -0.083, and dehydrate for 40min;

[0082] S2, add 50g of phenylboronic acid and 1.3g of p-toluenesulfonic acid, introduce nitrogen (1.5L / min), and increase the temperature for borate esterification reaction (110℃); take samples every hour: measure the hydroxyl value by titration, and terminate the reaction when the hydroxyl value = 8mgKOH / g;

[0083] S3, after the reaction is completed, reduce the temperature to 63℃, add 0.8g of triethylamine to neutralize the acidity, slowly add 1180g of deionized water (temperature control = 60℃) into a high-speed disperser, emulsify for 30min, and the rotation speed during emulsification is 8000rpm, to obtain a cyclic borate-terminated water-based phenoxy resin dispersion;

[0084] S4, mix hollow ceramic microspheres and NDZ-201 titanate at a high speed of 1800rpm for 25min, and dry at 115℃ for 2.5h to obtain modified hollow ceramic microspheres, the mass of NDZ-201 titanate is 2.5wt% of the hollow ceramic microspheres;

[0085] S5, mix deionized water (the addition amount is 35% of the total mass of rutile titanium dioxide and modified flaky boron nitride), polycarboxylic acid sodium salt dispersant, mineral oil-based defoaming agent, rutile titanium dioxide, and modified flaky boron nitride, start a high-speed disperser, and pre-disperse for 13min at 1800rpm, to obtain a pre-dispersed mixture after mixing;

[0086] S6, add the cyclic borate-terminated water-based phenoxy resin dispersion into a stirred tank, start moderate stirring (500rpm), and sequentially add the modified hollow ceramic microspheres, the pre-dispersed mixture, the rheological agent (hydrophobically modified polyurethane rheological agent), and the adhesion promoter (γ-glycidyl ether oxypropyl silane);

[0087] S7, the stirring speed is raised to 1400 rpm, and the dispersion is homogenized at high speed for 25 minutes;

[0088] S8, the blocked hexamethylene diisocyanate trimer is added, and the high-performance water-based phenoxy resin coating is obtained after uniform stirring.

[0089] The preparation method of the modified sheet-like boron nitride comprises the following steps:

[0090] (1) The sheet-like boron nitride is treated by an argon plasma processor, the power is 10 W / cm2, the speed through the treatment zone is 0.5 m / min (exposed for 120 s);

[0091] (2) The sheet-like boron nitride treated by the plasma is put into a 4% KH-560 epoxy silane ethanol solution according to the feeding ratio of 1 g:28 ml, ultrasonic treatment is performed at 60°C for 35 min, centrifugal separation is performed, and the sheet-like boron nitride modified by monosilane is obtained after ethanol cleaning / drying;

[0092] (3) The sheet-like boron nitride modified by monosilane is put into a 1.5% tridecafluorooctyltriethoxysilane ethanol solution according to the feeding ratio of 1 g:18 ml, immersed for 3 h, centrifuged and dried to obtain sheet-like boron nitride modified by disilane;

[0093] (4) The sheet-like boron nitride modified by disilane is put into anhydrous ethanol, and the mass ratio of the sheet-like boron nitride modified by disilane to anhydrous ethanol is 100:76;

[0094] (5) Tetraethyl orthosilicate is added, and then an ammonia water solution with a mass concentration of 8.5% is added dropwise (1 mL / min), the mass ratio of the sheet-like boron nitride modified by disilane to tetraethyl orthosilicate to the ammonia water solution is 100:22:3.8, and the reaction is performed at 55°C for 4.5 h, and the modified sheet-like boron nitride is obtained after centrifugal separation, washing and drying.

[0095] Example 3

[0096] A high-performance water-based phenoxy resin coating, the raw materials of which include, by mass fraction, 60 parts of a cyclic borate-terminated water-based phenoxy resin dispersion, 20 parts of modified sheet-like boron nitride, 15 parts of titanium ester modified hollow ceramic microspheres, 10 parts of blocked hexamethylene diisocyanate trimer, 8 parts of rutile titanium dioxide, 1.2 parts of polycarboxylic acid sodium salt dispersant, 0.5 parts of mineral oil-based defoaming agent, 1 part of hydrophobically modified polyurethane rheological agent, and 1.5 parts of γ-glycidyl ether propyl silane.

[0097] A preparation method of a high-performance water-based phenoxy resin coating based on the high-performance water-based phenoxy resin coating described in the embodiment, comprising the following steps:

[0098] S1, mix the aqueous phenoxy resin dispersion 1000g with N-methyl pyrrolidone 830g and heat to 85℃, the solid content of the aqueous phenoxy resin dispersion is 40%, vacuumize the reaction system to -0.080 MPa and dehydrate for 40 min;

[0099] S2, add phenylboronic acid 52g and p-toluenesulfonic acid 1.35g, and introduce nitrogen (1.5 L / min), and raise the temperature to perform borate esterification reaction (110℃); sample every hour: measure the hydroxyl value by titration, and terminate the reaction when the hydroxyl value = 8 mgKOH / g;

[0100] S3, after the reaction is completed, cool to 65℃, add triethylamine 0.85g to neutralize the acidity, slowly add deionized water 1200g (temperature control = 50℃) to a high-speed disperser, emulsify for 30 min, the speed during emulsification is 8000 rpm, and then a cyclic borate capped aqueous phenoxy resin dispersion is obtained;

[0101] S4, mix the hollow ceramic microspheres and NDZ-201 titanate at 2000 rpm for 20 min, and dry at 120℃ for 3 h to obtain modified hollow ceramic microspheres, the mass of the NDZ-201 titanate is 3% of the mass of the hollow ceramic microspheres;

[0102] S5, mix deionized water (the amount added is 35% of the total mass of the rutile titanium dioxide and the modified flaky boron nitride), polycarboxylic acid sodium salt dispersant, mineral oil-based defoaming agent, rutile titanium dioxide and modified flaky boron nitride, start the high-speed disperser, and pre-disperse at 1500 rpm for 15 min, and then mix to obtain a pre-dispersed mixture;

[0103] S6, add the cyclic borate capped aqueous phenoxy resin dispersion to a stirred tank, start moderate stirring (600 rpm), and then add the modified hollow ceramic microspheres, the pre-dispersed mixture, rheological agent (hydrophobically modified polyurethane rheological agent) and adhesion promoter (γ-glycidyl ether oxypropyl silane) in sequence;

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

[0105] S8, add blocked hexamethylene diisocyanate trimer, and uniformly stir to obtain the high-performance aqueous phenoxy resin coating.

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

[0107] (1) treat the flaky boron nitride by argon plasma processor, power 10 W / cm 2 at a speed of 0.5 m / min through the treatment zone (exposed for 120 s);

[0108] (2) The flaky boron nitride after plasma treatment was placed in a 5% KH-560 epoxy silane anhydrous ethanol solution according to a ratio of 1 g:30 ml, ultrasonic treatment was performed at 60°C for 40 min, and then centrifugal separation, ethanol cleaning / drying were performed to obtain monosilane-modified flaky boron nitride;

[0109] (3) The monosilane-modified flaky boron nitride was placed in a 1.5% tridecafluorooctyltriethoxysilane anhydrous ethanol solution according to a ratio of 1 g:20 ml, and then immersed for 4 h, and then centrifugal separation and drying were performed to obtain disilane-modified flaky boron nitride;

[0110] (4) The disilane-modified flaky boron nitride was placed in anhydrous ethanol, and the mass ratio of the disilane-modified flaky boron nitride to anhydrous ethanol was 100:78;

[0111] (5) Tetraethyl orthosilicate was added, and then a 9% ammonia water solution was added dropwise (1 mL / min), and the mass ratio of the disilane-modified flaky boron nitride to tetraethyl orthosilicate to the ammonia water solution was 100:23:4, and then reaction was performed at 60°C for 5 h, and then centrifugal separation, cleaning and drying were performed to obtain the modified flaky boron nitride.

[0112] Comparative Example 1

[0113] The comparative example was the same as Example 1, except that the preparation process of the modified flaky boron nitride in the comparative example did not have steps (4) and (5), and the modified flaky boron nitride in the comparative example was disilane-modified flaky boron nitride.

[0114] Comparative Example 2

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

[0116] Comparative Example 3

[0117] The comparative example was the same as Example 1, except that the modified flaky boron nitride in the comparative example was modified flaky boron nitride 10 parts.

[0118] Comparative Example 4

[0119] The comparative example was the same as Example 1, except that the modified flaky boron nitride in the comparative example was modified flaky boron nitride 25 parts.

[0120] After the high-performance water-based phenoxy resin coatings of Examples 1-3 and Comparative Examples 1-4 were cured at 120°C for 30 min, relevant tests were performed.

[0121] The volume resistivity test refers to the test standard GB / T 1410-2006, and the test results are shown in Table 1.

[0122] Table 1 Volume resistivity of each group of water-based phenoxy resin coatings

[0123]

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

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

[0126]

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

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

[0129]

[0130] The cold-heat cycle resistance test (-40~120℃) refers to the test standard GB / T 1735-2009, and the test results are shown in Table 4.

[0131] Table 4 Cold-heat cycle resistance of each group of water-based phenoxy resin coatings

[0132]

[0133] From the test data in Tables 1-4, it can be seen that the water-based phenoxy resin coating of the present application has good insulation and thermal insulation properties.

[0134] From the test data in Comparative Example 1 and Comparative Example 1, it can be seen that the double-silane modified flaky boron nitride without being modified by ethanol and tetraethyl orthosilicate will reduce the thermal insulation and insulation of the coating, because the double-silane modified flaky boron nitride without being modified by ethanol and tetraethyl orthosilicate has only the surface modified by double-silane (KH-560 and tridecafluorooctyltriethoxysilane), and lacks the silica coating formed by the hydrolysis of tetraethyl orthosilicate, which leads to the following problems: on the one hand, the interface bonding force between the flaky boron nitride and the resin matrix is weak, and interface defects (such as voids and bubbles) are easily formed, which will become a channel for heat conduction and a path for charge leakage, reducing the thermal insulation and insulation; on the other hand, the lack of The barrier effect of the coating, the bisilane-modified layer may be hydrolyzed and detached during the preparation or use of the coating due to environmental factors (such as humidity, temperature), resulting in a decrease in the dispersibility of the boron nitride flake layer, stacking agglomeration, and the inability to form a continuous and stable heat insulation and insulation network, thereby significantly weakening the heat insulation (increase in thermal conductivity) and insulation performance (decrease in volume resistivity and decrease in breakdown voltage) of the coating. As can be seen from the test data in Comparative Example 1 and Comparative Example 2, the addition of the modified flaky boron nitride can affect the heat insulation, insulation, and cold-heat cycle resistance of the coating.

[0135] As can be seen from the observation of Table 1 and Table 2, and the comparison of the test data in Comparative Example 1 and Comparative Example 3 and Comparative Example 4, the addition amount of the modified flaky boron nitride can affect the heat resistance and insulation of the coating, because the layered structure and excellent intrinsic properties (high thermal conductivity and high insulation) of the modified flaky boron nitride need to form an effective functional network through a reasonable addition amount: when the addition amount is insufficient, the flake layer is difficult to build a continuous heat conduction path and insulation barrier, heat is easily transmitted through the resin matrix, and charges are also easily leaked at defects, resulting in limited improvement in heat resistance (such as heat distortion temperature and thermal weight stability) and insulation (volume resistivity and breakdown voltage); when the addition amount is too high, the flake layer is easily agglomerated to form local defects (such as voids and stacking), which destroys the continuity of the resin matrix, and instead increases the heat conduction channels and charge migration paths, and at the same time, the high filling amount reduces the interfacial bonding force of the coating, resulting in a decrease in heat resistance and insulation.

[0136] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A high-performance waterborne phenoxy resin coating, characterized in that, The raw materials, by weight, include: 40-60 parts of cyclic borate ester-terminated aqueous phenoxy resin dispersion, 15-20 parts of modified flake 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 defoamer, 0.5-1 parts of rheology modifier, and 0.5-1.5 parts of adhesion promoter. The preparation method of the modified flake boron nitride includes the following steps: (1) Plasty boron nitride was plasma-treated using an argon plasma processor; (2) The ion-treated flake boron nitride was placed in a KH-560 epoxy silane ethanol solution with a mass concentration of 3-5% at a feeding ratio of 1g:25-30ml. After sonication, centrifugation, ethanol washing and drying, monosilane modified flake boron nitride was obtained. (3) The monosilane-modified flake boron nitride was placed in a 1.5% (w / w) tridecafluorooctyltriethoxysilane ethanol solution at a feeding ratio of 1g:15-20ml, impregnated, and then centrifuged and dried to obtain bissilane-modified flake boron nitride. (4) Place the bissilane-modified plate boron nitride in anhydrous ethanol, with a mass ratio of bissilane-modified plate boron nitride to anhydrous ethanol of 100:74-78. (5) Add tetraethyl orthosilicate and dropwise add an aqueous solution of ammonia with a mass concentration of 8-9%, wherein the mass ratio of bissilane-modified plate boron nitride, tetraethyl orthosilicate and aqueous solution of ammonia is 100:21-23:3.6-4. After reaction, the modified plate boron nitride is obtained after centrifugation, washing and drying.

2. The high-performance waterborne phenoxy resin coating according to claim 1, characterized in that, The modified hollow ceramic microspheres are titanate-modified hollow ceramic microspheres.

3. The high-performance waterborne phenoxy resin coating according to claim 1, characterized in that, The dispersant is a sodium polycarboxylate dispersant, the defoamer is a mineral oil-based defoamer, the rheology modifier is a hydrophobically modified polyurethane rheology modifier, and the adhesion promoter is γ-glycidyl etheroxypropylsilane.

4. A method for preparing a high-performance waterborne phenoxy resin coating according to any one of claims 1-3, characterized in that, Includes the following steps: S1. After mixing the aqueous phenoxy resin dispersion with N-methylpyrrolidone, the mixture is heated, vacuumed, and dehydrated. S2. Add phenylboronic acid and p-toluenesulfonic acid, heat up, and react. S3. After the reaction is complete, cool down, add triethylamine, then add deionized water, and disperse in a high-speed disperser to obtain a cyclic borate ester-terminated aqueous phenoxy resin dispersion. S4. Mix hollow ceramic microspheres with titanate and dry to obtain modified hollow ceramic microspheres; S5. Mix deionized water, dispersant, defoamer, rutile titanium dioxide and modified flake boron nitride to obtain a pre-dispersed mixture. S6. Add the cyclic borate-terminated aqueous phenoxy resin dispersion to the mixing tank, start stirring, and add the modified hollow ceramic microspheres, pre-dispersed mixture, rheology modifier and adhesion promoter in sequence. S7. Increase the stirring speed to continuously disperse and homogenize at high speed; S8. Add blocked hexamethylene diisocyanate trimer and stir to obtain a high-performance waterborne phenoxy resin coating.

5. The method according to claim 4, 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.

6. The method according to claim 4, characterized in that, The mass ratio of the aqueous phenoxy resin dispersion, phenylboronic 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 the aqueous phenoxy resin dispersion in S3 is 11-12:

10.

7. The method according to claim 4, characterized in that, S4 specifically involves mixing hollow ceramic microspheres and NDZ-201 titanate at a high speed of 1500-2000 rpm for 20-30 min, and drying at 110-120℃ for 2-3 h to obtain modified hollow ceramic microspheres. The mass of NDZ-201 titanate is 2-3 wt% of the hollow ceramic microspheres.

8. An application of a high-performance waterborne phenoxy resin coating according to any one of claims 1-3 in the field of insulating coatings.

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