Ultraviolet-cured composite coating as well as preparation method and application thereof

Abstract

The invention discloses an ultraviolet-cured composite coating as well as a preparation method and application thereof, and belongs to the technical field of insulating materials. The phenolic aldehyde modified acrylate is good in insulativity, polyolefin in the polyolefin modified polyurethane acrylate is good in temperature resistance and moisture resistance, the electrical performance of the ultraviolet-cured composite coating is enhanced by mixing the phenolic aldehyde modified acrylate and the polyolefin modified polyurethane acrylate, and the temperature resistance, the moisture resistance and the corrosion resistance of the ultraviolet-cured composite coating are also improved; meanwhile, the active diluent dissolves and disperses all the components, the adhesion promoter can form chemical bonds or relatively strong intermolecular force between a base material and the ultraviolet-cured composite coating, the adhesion of the ultraviolet-cured composite coating to the base material is improved, and finally, the ultraviolet-cured composite coating with high crosslinking density and good adhesion is prepared through ultraviolet curing. And the hardness, the wear resistance and the chemical resistance of the ultraviolet-cured composite coating are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of insulating materials, and particularly relates to a composite coating cured by ultraviolet light, a preparation method thereof, and an application thereof. Background Art

[0002] The core of new energy vehicles lies in the power batteries and energy storage batteries of the vehicles. In new energy vehicles, the batteries supply power to the vehicle in series. To save space, the distance between each series-connected battery is usually shortened and they are closely attached together. This leads to friction between the closely attached batteries due to bumps or sudden stops during vehicle driving, resulting in conduction short circuits, which may cause fires or explosions. Therefore, the insulating material wrapped outside the battery needs to have better insulation, and also needs to have excellent toughness and impact resistance. As people's requirements for the cruising range of the power batteries of new energy vehicles are getting higher and higher, the charging rate of the batteries is also required to be faster and faster. During the charging process, alternating current needs to be converted into high-voltage direct current, and these direct currents are directly input into the batteries of electric vehicles to shorten the charging time. Currently, the charging voltage has been increased from 400V to 800V, which poses higher requirements for the insulating material outside the battery, such as higher insulation withstand voltage, better impact resistance, bending resistance, and better liquid resistance.

[0003] The battery insulating material of new energy vehicles is generally a modified material of polyolefins. Among them, the poly(ethylene terephthalate) (PET) film material is relatively common. For example, Patent CN115260933A discloses a flexible sheet of poly(ethylene terephthalate) and a thermally activated adhesive and a thermal cooling structure using the same, including a first layer of poly(ethylene terephthalate) having opposite first and second surfaces and electrical insulation of at least 500 ohms at 2.0 kV DC, and a second layer of thermally activated adhesive attached to and covering the first surface. The PET blue film has problems such as low sticking yield, low adhesion between the pressure-sensitive adhesive, the battery cell, and the PET, which easily causes bubbling, slipping, and falling off. This results in the risk of flammability and short circuits in the battery after long-term use.

[0004] To overcome this problem, the material is mostly attached to the outer layer of the battery by spraying. For example, Patent CN110760238B discloses a powder coating and its preparation method. By weight, it contains the following components: 150-200 parts of epoxy resin, 10-50 parts of modified epoxy resin, 5-20 parts of curing agent, 0.1-3 parts of curing accelerator, 50-150 parts of filler, 5-20 parts of auxiliary agent, and 0.5-10 parts of pigment. The powder coating has good insulation, is resistant to high voltage, acids and alkalis, and organic solvents. When the powder coating is sprayed at 200-300 μm, the coating is not broken down under a voltage of 5000 V; after continuous baking at 155 °C for 400 hours, the coating is not broken down under a voltage of 5000 V. Among them, the sprayed powder insulating material needs to be baked for a long time to meet the use requirements, with high energy consumption and low efficiency.

[0005] However, at present, the processing method of the battery insulation material for new energy vehicles has gradually changed to ultraviolet (UV) curing. Compared with the traditional thermal curing process, UV curing is faster, can significantly shorten the production cycle, improve production efficiency, and the cured insulation material is thin and dense, which can perfectly fit on the outer layer of the battery, and the curing process is more environmentally friendly.

[0006] For example, Patent CN117916290A discloses an ultraviolet curable resin composition, adhesive, sealant, insulation protector, and electronic circuit board, which includes: substance (A), which is at least 1 selected from poly(meth)acrylate (a1) and polyethylene ether (a2); compound (B), which has at least 2 mercapto groups in its molecule; photoinitiator (C), whose absorbance at 385 nm in an acetonitrile solution with a concentration of 500 ppm and an optical path length of 10 mm is 0.10 or more; and photosensitizer (D), and the above materials are cured by irradiating ultraviolet light.

[0007] Patent CN115806764A discloses an insulating coating for new energy vehicle batteries and its preparation method, including alicyclic epoxy resin, reactive monomer, fumed silica, quartz powder, wetting and dispersing agent, cationic photoinitiator, and photosensitizing agent. The prepared insulating coating is applied to the outer surface shell of the workpiece of the new energy vehicle battery by air spraying, baked at 40-60 °C for 3-5 minutes, and then transferred to a UV furnace for curing with an energy of 5000-8000 mJ / cm 2 The technical solution uses an epoxy cationic photocuring system to prepare UV insulating paint, and the cationic photocuring system has problems such as relatively slow curing speed, being easily affected by moisture, relatively few types of cationic resin monomers, poor performance adjustability, and high cost.

[0008] Patent US20230002636A1 discloses a UV insulating coating comprising one or more acrylate monomers, a polyurethane prepolymer, a crosslinker, at least one tackifier, a photoinitiator, and optionally one or more fillers and / or additives. The coating can be used to insulate battery cells and battery packs, such as battery cells and battery packs used in electric vehicles. The coating can be easily applied and cured quickly. The cured coating can also have high adhesion strength even after exposure to humid conditions. However, 17.5% of fumed silica is added to the technical solution, and the porous structure of a large amount of fumed silica is bound to lead to a decrease in liquid resistance.

[0009] In summary, in order to improve the safety level of new energy vehicles, it is particularly important to improve the insulation, impact resistance and high temperature resistance of the insulating material of the outer layer of the battery. The preparation method of traditional insulating materials has problems such as short film life, easy shedding, difficult process, low efficiency, etc. The ultraviolet curing process has replaced the conventional thermal curing process to improve efficiency and enhance life. However, due to the current requirements for the endurance of new energy vehicles and other reasons, the insulation, impact resistance, bending resistance, electrolyte resistance, high temperature resistance, moisture resistance and other properties of the insulating material cannot meet the requirements, which is still a problem to be solved urgently. Summary of the invention

[0010] In view of the above problems, the present invention provides a composite coating cured by ultraviolet light, a preparation method and an application thereof, which is prepared by mixing phenolic modified acrylate, polyolefin modified polyurethane acrylate and other additives in a certain ratio, and thereby preparing an insulating material, wherein the insulating material has strong adhesion, good pressure resistance and high insulation.

[0011] The invention provides a composite coating cured by ultraviolet light. The composite coating cured by ultraviolet light is obtained by mixing phenolic modified acrylate, polyolefin modified polyurethane acrylate, reactive diluent, adhesion promoter, leveling agent, dispersant, defoamer, pigment, filler and photoinitiator, and then spraying and curing. The composite coating cured by ultraviolet light has an adhesion grade of 0 and a pencil hardness of HB-2H. The composite coating cured by ultraviolet light has an insulation resistance of more than 1GΩ after polarization at 1000V / 60s and a leakage current of less than 0.1mA after polarization at 5000V / 60s. The UV-cured composite coating has no changes in adhesion and pencil hardness after being impacted in a vertical direction of 1kg*50cm, being bent around a shaft with a curvature radius of 0.5mm, being immersed in a room temperature electrolyte for 30 days, being immersed in an electrolyte at 85°C for 4 hours, and being stored in a neutral salt spray condition for 2000 hours. The surface has no paint exposure, no cracks, no bubbling, no shedding, and no changes in insulation resistance and leakage current. After being stored at 85°C and 85% RH for 2000 h, the adhesion and pencil hardness of the ultraviolet-cured composite coating remain unchanged, the surface has no paint peeling, cracks, bubbles, or peeling, the surface has slight discoloration, the insulation resistance and leakage current remain unchanged, and the bonding strength is 12 - 20 MPa; After 1000 h of thermal cycling at -40 to 85°C, the adhesion and pencil hardness of the ultraviolet-cured composite coating remain unchanged, the surface has no paint peeling, cracks, bubbles, or peeling, the surface has slight discoloration, the insulation resistance and leakage current remain unchanged, and the bonding strength is 12 - 20 MPa.

[0012] Furthermore, the components and their contents in the ultraviolet-cured composite coating are as follows: Phenol-formaldehyde modified acrylate: 10 - 40 parts by weight; Polyolefin modified polyurethane acrylate: 5 - 40 parts by weight; Reactive diluent: 20 - 60 parts by weight; Adhesion promoter: 1 - 8 parts by weight; Leveling agent: 0.1 - 0.5 parts by weight; Dispersant: 0.1 - 5 parts by weight; Defoamer: 0.1 - 5 parts by weight; Pigment: 1 - 20 parts by weight; Filler: 0.5 - 40 parts by weight; Photoinitiator: 3 - 6 parts by weight.

[0013] Furthermore, when the thickness of the phenol-formaldehyde modified acrylate is 40 μm, the withstand voltage strength is 6 kV, and when the thickness is 110 μm, the withstand voltage strength is 8 - 11 kV.

[0014] Furthermore, the phenol-formaldehyde modified acrylate is one or more of phenol-formaldehyde modified epoxy acrylate and phenol-formaldehyde modified polyurethane acrylate.

[0015] Furthermore, the modification process of the phenol-formaldehyde modified epoxy acrylate is as follows: At 40 - 60°C, add 1 mol of o-cresol novolac epoxy resin, 0.1 - 0.3% of benzyltriethylammonium chloride based on the total mass of the substances, 300 - 800 ppm of 4-methoxyphenol based on the total mass of the substances, and 100 - 200 ppm of phenothiazine based on the total mass of the substances. Then add 1 mol of acrylic acid or methacrylic acid and continuously bubble at 200 mL / min. Continue heating to 80 - 100°C and keep it warm for 2 - 5 h until the difference between the acid value in the system and the initial acid value is < 5 mg / KOH / g and the epoxy value is < 0.03, then the reaction ends to obtain the phenol-formaldehyde modified epoxy acrylate.

[0016] Furthermore, the modification process of the phenol-formaldehyde modified polyurethane acrylate is as follows: 2.0 - 2.15 mol of diisocyanate is added dropwise to 0.1 - 1 mol of polyol, and the mixture is stirred and heated to 40 - 85 °C at 300 - 500 r / min. After reacting for 0.5 - 4 h, 0.2 - 2 mol of o-cresol formaldehyde resin is added, and the reaction continues for 0.5 - 4 h. Finally, 2.0 - 2.2 mol of capping agent is added and reacted for 2 - 6 h. The reaction is terminated when the NCO content in the system is lower than 0.1% at 40 - 85 °C, and phenolic modified polyurethane acrylate is obtained.

[0017] Furthermore, the water absorption rate of the polyolefin modified polyurethane acrylate after being soaked in normal temperature water for 1000 h is 0.15%. After being soaked in normal temperature electrolyte for 1000 h, after 2000 h of thermal cycling at -40 to 85 °C, and after steaming at 85 °C and 1000% RH for 1000 h, there are no bubbles, no peeling, and it has insulation withstand voltage.

[0018] Furthermore, the modification process of the polyolefin modified polyurethane acrylate is as follows: 2.0 - 2.15 mol of diisocyanate and 0.1 - 1 mol of polyol are stirred and reacted at 100 - 800 r / min and 40 - 85 °C for 0.5 - 4 h. Then 1 - 2 mol of polyolefin is added, and the reaction continues for 0.5 - 4 h. Finally, 2.0 - 2.2 mol of capping agent is added and reacted for 2 - 6 h. The reaction is terminated when the NCO content in the system is lower than 0.1%, and the polyolefin modified polyurethane acrylate is obtained.

[0019] Furthermore, the polyolefin in the polyolefin modified polyurethane acrylate is one or more of polybutadiene, polybutadiene - acrylonitrile, and polybutadiene - styrene.

[0020] Furthermore, in the modification processes of the phenolic modified polyurethane acrylate and the polyolefin modified polyurethane acrylate, the diisocyanate is one or more of toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI), xylylene diisocyanate (XDI), 2,2,4 - trimethylhexamethylene diisocyanate (TMDI), isophorone diisocyanate (IPDI), and hexamethylene diisocyanate (HDI).

[0021] Further, in the modification processes of the phenolic modified polyurethane acrylate and the polyolefin modified polyurethane acrylate, the polyol is one or more of polypropylene glycol, polypropylene glycol, polypropylene triol, polycaprolactone diol, polytetrahydrofuran diol, polyhexylene adipate diol, neopentyl adipate diol, diethylene adipate diol, ethylene glycol propylene glycol adipate diol, polycarbonate diol, neopentyl isophthalate adipate diol, castor oil and castor oil derivatives.

[0022] Further, in the modification processes of the phenolic modified polyurethane acrylate and the polyolefin modified polyurethane acrylate, the capping agent is one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate and hydroxypropyl methacrylate.

[0023] Further, the reactive diluent is one or more of (ethoxy) phenol acrylate, 2-(propoxy) nonylphenol acrylate, phenyl methacrylate, benzyl acrylate, benzyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, dicyclopentene acrylate, isobornyl acrylate, isobornyl methacrylate, acryloylmorpholine, tetrahydrofuran acrylate, tetrahydrofuran methacrylate, 4-tert-butylcyclohexyl acrylate, 4-tert-butylcyclohexyl methacrylate, isooctyl acrylate, isooctyl methacrylate, isodecyl acrylate, isodecyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, bisphenol fluorene diacrylate, ethoxylated bisphenol fluorene diacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, dipropylene glycol diacrylate, dipropylene glycol dimethacrylate, 1,3-propanediol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tricyclodecane dimethanol diacrylate, tricyclodecane dimethanol dimethacrylate, diallyl isocyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, ethoxylated trimethylolpropane triacrylate, bis-trimethylolpropane tetraacrylate, isocyanuric acid triacrylate, pentaerythritol triacrylate and dipentaerythritol hexaacrylate.

[0024] Further, the adhesion promoter is one or more of titanate, monofunctional acid ester modifier, trifunctional phosphate modifier, 3-acryloxypropyltrimethoxysilane and tetra-neoalkoxy bis(didecyl phosphite acyloxy) titanate.

[0025] Further, the leveling agent is a polyether silicone copolymer.

[0026] Further, the dispersant is a polymer segment with an amphiphilic molecular structure, and the amphiphilic molecular structure includes a pigmentophilic group and a solventophilic group; The pigmentophilic group is a polar group, including one or more of a carboxyl group, a sulfonic acid group, and an amino group; The solventophilic group is a nonpolar group, including one or more of a long-chain hydrocarbon group and a polyether segment; The polymer segment includes one or more of an acrylic polymer and a polyether polymer.

[0027] Further, the density of the dispersant is 0.94 - 1.06 kg / m³.

[0028] Further, the defoamer is one or more of a silicone-free defoamer, an organically modified polysiloxane, and a self-emulsifying defoamer.

[0029] Further, the pigment is one or more of iron oxide black, carbon black, titanium dioxide, iron oxide yellow, iron oxide red, phthalocyanine blue, and phthalocyanine green.

[0030] Further, the filler includes one or more of mica powder, barium sulfate, kaolin, talc powder, silica powder, alumina, fumed silica, polytetrafluoroethylene wax powder, zinc phosphate, glass flakes, calcium ion-exchanged anti-rust pigment, magnesium dihydrogen phosphate, and zinc phosphomolybdate.

[0031] Further, the photoinitiator includes one or more of 2-hydroxy-2-methylpropiophenone, 1-hydroxycyclohexyl phenyl ketone, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPPO), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), 4-chlorobenzophenone, methyl o-benzoylbenzoate, 2-isopropylthioxanthone, ethyl 4-dimethylaminobenzoate, benzophenone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, 2,2-dimethoxy-2-phenylacetophenone, and 2-methyl-2-(4-morpholinyl)-1-[4-(methylthio)phenyl]-1-propanone.

[0032] The present invention also provides a method for preparing the ultraviolet-cured composite coating, including the following steps: Step 1: Place phenolic modified acrylate, polyolefin modified polyurethane acrylate, active diluent, dispersant, and defoamer in a mixing tank and stir and mix to obtain a mixed material; Step 2: Add the pigment and filler to the mixing tank, continue to stir and mix with the mixed material, and sand mill after mixing evenly to obtain a fine material; Step 3: Add the adhesion promoter, leveling agent and photoinitiator into the mixing tank, continue to stir and mix with the fine material, and filter to obtain a liquid paint precursor; Step 4: Spray the paint precursor into a film and cure it to obtain the ultraviolet-cured composite paint.

[0033] Further, the mass ratio of the phenolic-modified acrylate, polyolefin-modified polyurethane acrylate, reactive diluent, dispersant and defoamer in the step 1 is (10 - 40):(5 - 40):(20 - 60):(0.1 - 5):(0.1 - 5).

[0034] Further, when the thickness of the phenolic-modified acrylate in the step 1 is 40 μm, the voltage resistance is 6 kV, and when the thickness is 110 μm, the voltage resistance is 8 - 11 kV.

[0035] Further, the phenolic-modified acrylate in the step 1 is one or more of phenolic-modified epoxy acrylate and phenolic-modified polyurethane acrylate.

[0036] Further, the modification process of the phenolic-modified epoxy acrylate is as follows: At 40 - 60 °C, add 1 mol of o-cresol novolac epoxy resin, 0.1 - 0.3% of benzyltriethylammonium chloride based on the total mass of the substances, 300 - 800 ppm of 4-methoxyphenol based on the total mass of the substances, and 100 - 200 ppm of phenothiazine based on the total mass of the substances. Then add 1 mol of acrylic acid or methacrylic acid and continuously bubble at 200 mL / min. Continue to heat to 80 - 100 °C and keep warm for 2 - 5 h until the difference between the acid value in the system and the initial acid value < 5 mg / KOH / g and the epoxy value < 0.03, then the reaction ends to obtain the phenolic-modified epoxy acrylate.

[0037] Further, the modification process of the phenolic-modified polyurethane acrylate is as follows: Drop 0.1 - 1 mol of polyol into 2.0 - 2.15 mol of diisocyanate, stir and heat to 40 - 85 °C at 300 - 500 r / min. After reacting for 0.5 - 4 h, add 0.2 - 2 mol of o-cresol novolac resin and continue to react for 0.5 - 4 h. Finally, add 2.0 - 2.2 mol of capping agent and react for 2 - 6 h. When the NCO content in the system is lower than 0.1% at 40 - 85 °C, the reaction ends to obtain the phenolic-modified polyurethane acrylate.

[0038] Further, the water absorption rate of the polyolefin-modified polyurethane acrylate soaked in normal-temperature water for 1000 h in Step 1 is 0.15%. After being soaked in normal-temperature electrolyte for 1000 h, after 2000 h of thermal cycling at -40 to 85°C, and after steaming at 85°C and 1000% RH for 1000 h, there are no bubbles, no peeling, and it has insulation withstand voltage.

[0039] Further, the modification process of the polyolefin-modified polyurethane acrylate is as follows: React 2.0 - 2.15 mol of diisocyanate with 0.1 - 1 mol of polyol by stirring at 100 - 800 r / min and 40 - 85°C for 0.5 - 4 h, then add 1 - 2 mol of polyolefin and continue to react for 0.5 - 4 h. Finally, add 2.0 - 2.2 mol of capping agent and react for 2 - 6 h. When the NCO content in the system is lower than 0.1%, the reaction ends to obtain the polyolefin-modified polyurethane acrylate.

[0040] Further, the polyolefin in the polyolefin-modified polyurethane acrylate is one or more of polybutadiene, polybutadiene-acrylonitrile, and polybutadiene-styrene.

[0041] Further, in the modification processes of the phenolic-modified polyurethane acrylate and the polyolefin-modified polyurethane acrylate, the diisocyanate is one or more of toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI), xylylene diisocyanate (XDI), 2,2,4-trimethylhexane diisocyanate (TMDI), isophorone diisocyanate (IPDI), and hexamethylene diisocyanate (HDI).

[0042] Further, in the modification processes of the phenolic-modified polyurethane acrylate and the polyolefin-modified polyurethane acrylate, the polyol is one or more of polyoxypropylene diol, polyoxypropylene diol, polyoxypropylene triol, polycaprolactone diol, polytetrahydrofuran diol, polyhexamethylene adipate diol, polyneopentyl adipate diol, poly(ethylene adipate) diol, poly(ethylene adipate propylene glycol) diol, polycarbonate diol, poly(neopentyl isophthalate adipate) diol, castor oil, and castor oil derivatives.

[0043] Further, in the modification processes of the phenolic-modified polyurethane acrylate and the polyolefin-modified polyurethane acrylate, the capping agent is one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate.

[0044] Further, the reactive diluent in the step 1 is one or more of (ethoxy)phenol acrylate, 2-(propoxy)nonylphenol acrylate, phenyl methacrylate, benzyl acrylate, benzyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, dicyclopentenyloxyethyl acrylate, isobornyl acrylate, isobornyl methacrylate, acryloylmorpholine, tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, 4-tert-butylcyclohexyl acrylate, 4-tert-butylcyclohexyl methacrylate, isooctyl acrylate, isooctyl methacrylate, isodecyl acrylate, isodecyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, bisphenol fluorene diacrylate, ethoxylated bisphenol fluorene diacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, dipropylene glycol diacrylate, diethylene glycol diacrylate, 1,3-propanediol dimethacrylate, dipropylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tricyclodecane dimethanol diacrylate, tricyclodecane dimethanol dimethacrylate, diallyl isocyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, ethoxylated trimethylolpropane triacrylate, bis-trimethylolpropane tetraacrylate, isocyanuric acid triacrylate, pentaerythritol triacrylate, and dipentaerythritol hexaacrylate.

[0045] Further, the dispersant in the step 1 is a polymer segment with an amphiphilic molecular structure, and the amphiphilic molecular structure includes a pigmentophilic group and a solventophilic group; The pigmentophilic group is a polar group, including one or more of carboxyl group, sulfonic acid group, and amine group; The solventophilic group is a non-polar group, including one or more of long-chain hydrocarbon groups and polyether segments; The polymer segment includes one or more of acrylic polymers and polyether polymers.

[0046] Further, the density of the dispersant in the step 1 is 0.94 - 1.06 kg / m³.

[0047] Further, the defoamer in the step 1 is one or more of silicon-free defoamers, organically modified polysiloxanes, and self-emulsifying defoamers.

[0048] Further, the stirring speed in the step 1 is 500 - 1500 r / min, and the stirring time is 15 - 45 min.

[0049] Further, the mass ratio of the pigment, the filler and the phenolic modified acrylate in the step 2 is (1 - 20):(0.5 - 40):(10 - 40).

[0050] Further, the pigment in the step 2 includes one or more of iron oxide black, carbon black, titanium dioxide, iron oxide yellow, iron oxide red, phthalocyanine blue and phthalocyanine green.

[0051] Further, the filler in the step 2 includes one or more of mica powder, barium sulfate, kaolin, talc powder, silica powder, alumina, fumed silica, polytetrafluoroethylene wax powder, zinc phosphate, glass flake, calcium ion exchange type rust preventive pigment, magnesium dihydrogen phosphate and zinc phosphomolybdate.

[0052] Further, the speed of continuous stirring in the step 2 is 500 - 1500 r / min, and the time of continuous stirring is 15 - 45 min.

[0053] Further, the fineness of the fine material in the step 2 is < 15 μm.

[0054] Further, the mass ratio of the adhesion promoter, the leveling agent, the photoinitiator and the phenolic modified acrylate in the step 3 is (1 - 8):(0.1 - 0.5):(3 - 6):(10 - 40).

[0055] Further, the adhesion promoter in the step 3 includes one or more of titanate, monofunctional acid ester modifier, trifunctional phosphate modifier, 3 - acryloxypropyltrimethoxysilane and tetraalkoxy bis(didecyl phosphite) titanate.

[0056] Further, the leveling agent in the step 3 is a polyether silicone copolymer.

[0057] Further, the photoinitiator in the step 3 includes one or more of 2 - hydroxy - 2 - methylacetophenone, 1 - hydroxycyclohexyl phenyl ketone, diphenyl(2,4,6 - trimethylbenzoyl) phosphine oxide (TPPO), phenylbis(2,4,6 - trimethylbenzoyl) phosphine oxide (TPO), 4 - chlorobenzophenone, methyl o - benzoylbenzoate, 2 - isopropylthioxanthone, ethyl 4 - dimethylaminobenzoate, benzophenone, 2 - benzyl - 2 - dimethylamino - 1 - (4 - morpholinophenyl) butanone, 2,2 - dimethoxy - 2 - phenylacetophenone and 2 - methyl - 2 - (4 - morpholinyl) - 1 - [4 - (methylthio)phenyl] - 1 - propanone.

[0058] Further, the speed of continuous stirring in the step 3 is 500 - 1500 r / min, and the time of continuous stirring is 15 - 45 min.

[0059] Further, in the step 4, the spraying pressure is 1.5 - 4 bar, and the spraying distance is 15 - 25 cm.

[0060] Further, in the step 4, the thickness of the film is 80 - 130 μm.

[0061] Further, in the step 4, the curing speed is 1 - 20 m / min, the curing method is ultraviolet curing, and the irradiation intensity of the ultraviolet light is 300 - 500 mW / cm 2 .

[0062] The present invention also provides an insulating coating, which is prepared from the composite coating cured by ultraviolet light.

[0063] Advantages of the present invention: 1. In the present invention, after blending phenolic modified acrylate and polyolefin modified polyurethane acrylate and adding other additives for mixing, the polymer structure formed after curing of the phenolic modified acrylate is compact, which can effectively prevent the conduction of charges, making the material have a high volume resistivity, and can withstand a high voltage under the action of an electric field without breakdown, greatly reducing the leakage risk and ensuring the safe operation of electrical equipment. At the same time, it has good temperature and corrosion resistance; in the polyolefin modified polyurethane acrylate, the polyolefin and acrylate structures result in low water absorption and swelling, and in a humid environment, it can maintain stable insulation performance, avoiding the decline of insulation performance due to water absorption, and is suitable for electrical equipment in outdoor, underwater and other humid environments, and has good tolerance to common acids, alkalis, organic solvents and other chemical substances. Moreover, the long-chain structure of the polyolefin in the polyolefin modified polyurethane acrylate can also play an internal plasticizing role, improving the flexibility and processing performance of the composite coating cured by ultraviolet light, interpenetrating with the phenolic modified acrylate at the molecular level to form a uniform mixing system, enhancing the electrical performance of the composite coating cured by ultraviolet light during use, and also improving the temperature, humidity and corrosion resistance of the composite coating cured by ultraviolet light; 2. In the present invention, in addition to phenolic modified acrylate and polyolefin modified polyurethane acrylate, an active diluent is also added. The viscosity of the active diluent is low, which can make the phenolic modified acrylate and polyolefin modified polyurethane acrylate dissolve better. At the same time, after adding a leveling agent, a dispersant, an antifoaming agent, pigments and fillers, the dispersibility of the material will be better. In addition, the adhesion promoter in the present invention can form chemical bonds or strong intermolecular forces between the substrate and the composite coating cured by ultraviolet light, improving the adhesion of the composite coating cured by ultraviolet light to the substrate. Finally, the addition of a photoinitiator enables the composite coating cured by ultraviolet light in the present invention to be cured under the irradiation of ultraviolet light; 3. In the preparation process of the composite coating cured by ultraviolet in the present invention, first, phenolic modified acrylate, polyolefin modified polyurethane acrylate, dispersant, and defoamer are dissolved and dispersed in the active diluent, and then pigments and fillers are added for mixing to prevent the aggregation and caking caused by the large particle size or content of the pigments and fillers, which hinder the dissolution of phenolic modified acrylate and polyolefin modified polyurethane acrylate. Finally, adhesion promoter, leveling agent, and photoinitiator are added to the system to prevent the thermal decomposition of the adhesion promoter and leveling agent during the sanding process. At the same time, during the preparation process, the photoinitiator is prevented from being partially inactivated due to the long-term irradiation of natural light. After mixing, it is cured by ultraviolet irradiation. The ultraviolet curing speed is fast, and it is friendly to heat-sensitive substrates, and will not deform due to the heat sensitivity of the substrates. At the same time, the composite coating cured by ultraviolet has a high crosslinking density after ultraviolet curing, and has good hardness, wear resistance, and chemical resistance. Description of the Drawings

[0064] Figure 1 It is the surface state diagram of the composite coating cured by ultraviolet described in Example 2 after the impact resistance test; Figure 2 It is the surface state diagram of the composite coating cured by ultraviolet described in Example 2 after the bending resistance test; Figure 3 It is the surface state diagram of the composite coating cured by ultraviolet described in Comparative Example 2 after the impact resistance test; Figure 4 It is the surface state diagram of the composite coating cured by ultraviolet described in Comparative Example 2 after the bending resistance test. Detailed Description of the Embodiments

[0065] The following is a detailed description of the invention in combination with the embodiments: The present invention provides a composite coating cured by ultraviolet and its preparation method and application. Through the mixing and preparation method of the components in the present invention, the composite coating cured by ultraviolet prepared has strong adhesion, good corrosion resistance, and greatly improves its insulation performance.

[0066] Example 1 This example provides a composite coating cured by ultraviolet. The composite coating cured by ultraviolet is obtained by mixing phenolic modified acrylate, polyolefin modified polyurethane acrylate, active diluent, adhesion promoter, leveling agent, dispersant, defoamer, pigment, filler, and photoinitiator, and then spraying and curing; the adhesion grade of the composite coating cured by ultraviolet is 0 level, and the pencil hardness is H; the insulation resistance of the composite coating cured by ultraviolet after polarization at 1000V / 60s > 1GΩ, and the leakage current after polarization at 5000V / 60s < 0.1mA; After the UV-cured composite coating is impacted vertically at 1 kg * 50 cm, bent around a shaft rod with a curvature radius of 0.5 mm, soaked in normal-temperature electrolyte for 30 days, soaked in 85 °C electrolyte for 4 h, and stored under neutral salt spray conditions for 2000 h, the adhesion and pencil hardness remain unchanged, and there is no paint peeling, no cracking, no bubbling, and no peeling on the surface. The insulation resistance and leakage current do not change; After the UV-cured composite coating is stored at 85 °C and 85% RH for 2000 h, the adhesion and pencil hardness remain unchanged, there is no paint peeling, no cracking, no bubbling, and no peeling on the surface, the surface slightly changes color, the insulation resistance and leakage current do not change, and the bonding strength is 15.6 MPa; After the UV-cured composite coating undergoes 1000 h of thermal cycling from -40 to 85 °C, the adhesion and pencil hardness remain unchanged, there is no paint peeling, no cracking, no bubbling, and no peeling on the surface, the surface slightly changes color, the insulation resistance and leakage current do not change, and the bonding strength is 16.8 MPa.

[0067] In this embodiment, the components and their contents in the UV-cured composite coating are as follows: Phenolic-modified polyurethane acrylate: 15 parts by weight; Polybutadiene-modified polyurethane acrylate: 15 parts by weight; Reactive diluent: 35 parts by weight; Adhesion promoter: 3 parts by weight; Leveling agent: 0.3 parts by weight; Dispersant: 2 parts by weight; Defoaming agent: 0.5 parts by weight; Pigment: 6.2 parts by weight; Filler: 18 parts by weight; Photoinitiator: 5 parts by weight; The modification process of the phenolic-modified polyurethane acrylate is as follows: 2.0 mol of toluene diisocyanate is added dropwise to 1 mol of polytetrahydrofuran diol, and the reaction is carried out with stirring at 500 r / min and 65 °C for 2 h. 1 mol of o-cresol formaldehyde resin is added, and the reaction continues for 2 h. Finally, 2.2 mol of 2-hydroxyethyl methacrylate is added and the reaction is carried out for 4 h. The reaction ends at 65 °C when the NCO content in the system is lower than 0.1% to obtain the phenolic-modified polyurethane acrylate; The modification process of the polybutadiene-modified polyurethane acrylate is as follows: 2.15 mol of toluene diisocyanate and 1 mol of polytetrahydrofuran diol were stirred at 500 r / min and 65° C. for 2 h, and then 1 mol of polybutadiene was added and the reaction was continued for 2 h. Finally, 2.2 mol of hydroxyethyl methacrylate was added and the reaction was continued for 4 h. When the NCO content of the system was less than 0.1%, the reaction was terminated to obtain the polybutadiene-modified polyurethane acrylate. The active diluent is 20 parts by weight of isobornyl acrylate and 15 parts by weight of 4-tert-butyl cyclohexyl acrylate; The adhesion promoter is a trifunctional phosphate modified substance, the manufacturer is Arkema, and the brand is SR9054; The leveling agent is a polyether siloxane copolymer, manufactured by BYK, with a brand name of BYK379; The dispersant is a polymer segment with an amphiphilic molecular structure, and the brand is Lencolo 1108; The defoamer is a silicon-free defoamer, manufactured by Digo, with a brand name of TEGO920; The pigment is 0.2 parts by weight of red iron oxide, 1 part by weight of yellow iron oxide and 5 parts by weight of titanium dioxide; The filler comprises 15 parts by weight of mica powder and 3 parts by weight of zinc phosphomolybdate; The photoinitiator includes 3 parts by weight of 1-hydroxycyclohexyl phenyl ketone and 2 parts by weight of phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (TPO).

[0068] This embodiment also provides a method for preparing the composite coating by UV curing, comprising the following steps: Step 1, placing phenolic modified polyurethane acrylate, polybutadiene modified polyurethane acrylate, reactive diluent, dispersant and defoamer in a mixing tank and stirring and mixing at 800 r / min for 30 minutes to obtain a mixture; Step 2, adding pigment and filler into the mixing tank, and continuing to stir and mix with the mixture at 800r / min for 30min, and sand-grinding after mixing evenly to obtain fine material with a fineness of less than 15μm; Step 3, adding an adhesion promoter, a leveling agent and a photoinitiator into the mixing tank, stirring and mixing with the fine material at 800 r / min for 30 min, and filtering to obtain a liquid coating precursor; Step 4: After the coating precursor is sprayed into a film with a thickness of 100 μm, the coating precursor is sprayed at a speed of 5 m / min at 300 mW / cm 2 The composite coating is cured under ultraviolet irradiation intensity of , the spraying pressure is 1.5 bar, and the spraying distance is 15 cm to obtain the composite coating cured by ultraviolet.

[0069] Example 2 This embodiment provides a composite coating cured by ultraviolet light. The composite coating cured by ultraviolet light is obtained by mixing phenolic modified acrylate, polyolefin modified polyurethane acrylate, reactive diluent, adhesion promoter, leveling agent, dispersant, defoaming agent, pigment, filler and photoinitiator, and then through spraying and curing; the adhesion grade of the composite coating cured by ultraviolet light is grade 0, and the pencil hardness is H; the insulation resistance of the composite coating cured by ultraviolet light after polarization at 1000V / 60s is >1GΩ, and the leakage current after polarization at 5000V / 60s is <0.1mA; After the composite coating cured by ultraviolet light is impacted in the vertical direction of 1kg*50cm, bent around a shaft rod with a curvature radius of 0.5mm, soaked in normal temperature electrolyte for 30 days, soaked in 85°C electrolyte for 4h, and stored under neutral salt spray conditions for 2000h, the adhesion and pencil hardness remain unchanged, and there is no paint peeling, no crack, no bubbling, no peeling on the surface, and the insulation resistance and leakage current have no change; After the composite coating cured by ultraviolet light is stored at 85°C and 85%RH for 2000h, the adhesion and pencil hardness remain unchanged, there is no paint peeling, no crack, no bubbling, no peeling on the surface, the surface slightly discolors, the insulation resistance and leakage current remain unchanged, and the bonding strength is 15.3MPa; After the composite coating cured by ultraviolet light undergoes 1000h of thermal cycling from -40 to 85°C, the adhesion and pencil hardness remain unchanged, there is no paint peeling, no crack, no bubbling, no peeling on the surface, the surface slightly discolors, the insulation resistance and leakage current remain unchanged, and the bonding strength is 16.6MPa.

[0070] In this embodiment, the components and their contents in the composite coating cured by ultraviolet light are as follows: Phenolic modified epoxy acrylate: 18 parts by weight; Polybutadiene modified polyurethane acrylate: 10 parts by weight; Reactive diluent: 30 parts by weight; Adhesion promoter: 5 parts by weight; Leveling agent: 0.5 part by weight; Dispersant: 1 part by weight; Defoaming agent: 0.5 part by weight; Pigment: 5.5 parts by weight; Filler: 27 parts by weight; Photoinitiator: 2.5 parts by weight; The modification process of the phenolic modified epoxy acrylate is as follows: At 40 °C, 1 mol of o-cresol novolac epoxy resin was added with 0.3% of benzyltriethylammonium chloride based on the total mass of the substances, 500 ppm of 4-methoxyphenol based on the total mass of the substances, and 100 ppm of phenothiazine based on the total mass of the substances. Then, 1 mol of acrylic acid or methacrylic acid was added, and continuous bubbling was carried out at 200 mL / min. The mixture was further heated to 80 °C and held for 3 h. When the difference between the acid value in the system and the initial acid value was < 5 mg KOH / g and the epoxy value was < 0.03, the reaction ended, and phenolic modified epoxy acrylate was obtained. The modification process of the polybutadiene modified polyurethane acrylate is as follows: 2.15 mol of toluene diisocyanate and 1 mol of polytetrahydrofuran diol were stirred and reacted at 500 r / min and 65 °C for 2 h. Then, 1 mol of polybutadiene was added, and the reaction continued for 2 h. Finally, 2.2 mol of 2-hydroxyethyl methacrylate was added and reacted for 4 h. When the NCO content in the system was lower than 0.1%, the reaction ended, and the polybutadiene modified polyurethane acrylate was obtained. The active diluent is 30 parts by weight of isooctyl acrylate. The adhesion promoter is titanate. The leveling agent is a polyether silicone copolymer, manufactured by BYK, with the product number BYK3760. The dispersant has a polymer chain segment with an amphiphilic molecular structure, which is an acrylic copolymer, manufactured by BYK, with the product number BYK-2013. The defoaming agent is a silicone-free defoaming agent, manufactured by Degussa, with the product number TEGO900. The pigment is 0.5 part by weight of phthalocyanine blue and 5 parts by weight of titanium dioxide. The filler includes 25 parts by weight of mica powder and 2 parts by weight of zinc phosphate. The photoinitiator includes 1.5 parts by weight of 2-hydroxy-2-methylpropiophenone and 1 part by weight of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (TPO).

[0071] This example also provides a preparation method of the composite coating cured by ultraviolet light, including the following steps: Step 1: Put the phenolic modified epoxy acrylate, polybutadiene modified polyurethane acrylate, active diluent, dispersant, and defoaming agent into a mixing tank and stir and mix at 1000 r / min for 20 min to obtain a mixed material. Step 2: Add the pigment and filler into the mixing tank, continue to stir and mix with the mixed material at 1000 r / min for 20 min, and after mixing evenly, perform sand grinding to obtain a fine material with a fineness < 15 μm. Step 3: Add the adhesion promoter, leveling agent, and photoinitiator into the mixing tank, and continue to stir and mix with the fine material at 1000 r / min for 20 min, and then filter to obtain a liquid paint precursor; Step 4: After spraying the paint precursor into a film with a thickness of 120 μm, cure it at a speed of 5 m / min under an ultraviolet irradiation intensity of 500 mW / cm 2 , with the spraying pressure of 3 bar and the spraying distance of 20 cm, to obtain the ultraviolet-cured composite paint.

[0072] As Figure 1 is the surface state diagram of the ultraviolet-cured composite paint described in Example 2 after the impact resistance test. After the impact resistance test, there is no paint peeling, no crack, no bubbling, and no falling off on the surface; Figure 2 is the surface state diagram of the ultraviolet-cured composite paint described in Example 2 after the bending resistance test. After the bending resistance test, there is no paint peeling, no crack, no bubbling, and no falling off on the surface.

[0073] Example 3 This example provides an ultraviolet-cured composite paint, which is obtained by mixing phenolic modified acrylate, polyolefin modified polyurethane acrylate, reactive diluent, adhesion promoter, leveling agent, dispersant, defoamer, pigment, filler, and photoinitiator, and then through spraying and curing; the adhesion grade of the ultraviolet-cured composite paint is 0 level, and the pencil hardness is HB; the insulation resistance of the ultraviolet-cured composite paint after polarization at 1000 V / 60 s > 1 GΩ, and the leakage current after polarization at 5000 V / 60 s < 0.1 mA; After the ultraviolet-cured composite paint is impacted in the vertical direction of 1 kg * 50 cm, bent around a shaft rod with a curvature radius of 0.5 mm, soaked in normal temperature electrolyte for 30 days, soaked in 85 °C electrolyte for 4 h, and stored under neutral salt spray conditions for 2000 h, the adhesion and pencil hardness remain unchanged, there is no paint peeling, no crack, no bubbling, and no falling off on the surface, and the insulation resistance and leakage current do not change; After the ultraviolet-cured composite paint is stored at 85 °C and 85% RH for 2000 h, the adhesion and pencil hardness remain unchanged, there is no paint peeling, no crack, no bubbling, and no falling off on the surface, the surface slightly discolors, the insulation resistance and leakage current do not change, and the bonding strength is 13.2 MPa; After the ultraviolet-cured composite paint undergoes 1000 h of thermal cycling from -40 to 85 °C, the adhesion and pencil hardness remain unchanged, there is no paint peeling, no crack, no bubbling, and no falling off on the surface, the surface slightly discolors, the insulation resistance and leakage current do not change, and the bonding strength is 14.6 MPa.

[0074] In this embodiment, the components and their contents in the composite coating cured by ultraviolet light are as follows: Phenol-formaldehyde modified epoxy acrylate: 15 parts by weight; Polybutadiene-styrene modified polyurethane acrylate: 40 parts by weight; Reactive diluent: 30 parts by weight; Adhesion promoter: 5 parts by weight; Leveling agent: 0.3 parts by weight; Dispersant: 0.5 parts by weight; Defoamer: 0.2 parts by weight; Pigment: 3.5 parts by weight; Filler: 0.5 parts by weight; Photoinitiator: 5 parts by weight; The modification process of the phenol-formaldehyde modified epoxy acrylate is as follows: At 40°C, add 1 mol of o-cresol novolac epoxy resin, 0.3% of benzyltriethylammonium chloride based on the total mass of the substances, 500 ppm of 4-methoxyphenol based on the total mass of the substances, and 100 ppm of phenothiazine based on the total mass of the substances. Then add 1 mol of acrylic acid or methacrylic acid and continuously bubble at 200 mL / min. Continue to heat to 80°C and keep it warm for 3 h. When the difference between the acid value in the system and the initial acid value is < 5 mg / KOH / g and the epoxy value is < 0.03, the reaction ends, and the phenol-formaldehyde modified epoxy acrylate is obtained; The modification process of the polybutadiene-styrene modified polyurethane acrylate is as follows: React 2.15 mol of toluene diisocyanate with 1 mol of polytetrahydrofuran glycol under stirring at 500 r / min and 65°C for 2 h. Then add 1 mol of polybutadiene-styrene and continue the reaction for 2 h. Finally, add 2.2 mol of 2-hydroxyethyl methacrylate and react for 4 h. When the NCO content in the system is lower than 0.1%, the reaction ends, and the polybutadiene-styrene modified polyurethane acrylate is obtained; The reactive diluent is isodecyl acrylate; The adhesion promoter is titanate; The leveling agent is a polyether silicone copolymer, manufactured by Degussa, with the product number TEGO280; The dispersant has a polymer segment with an amphiphilic molecular structure, manufactured by Degussa, with the product number TEGO 688; The defoamer is a silicone-free defoamer, manufactured by Degussa, with the product number TEGO920; The pigment is 0.5 parts by weight of phthalocyanine blue and 3 parts by weight of titanium dioxide; The filler includes 0.5 parts by weight of fumed silica; The photoinitiator includes 2 parts by weight of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide and 3 parts by weight of 1-hydroxycyclohexyl phenyl ketone.

[0075] This example also provides a method for preparing the ultraviolet-cured composite coating, including the following steps: Step 1: Place phenolic modified epoxy acrylate, polybutadiene-styrene modified polyurethane acrylate, active diluent, dispersant and defoamer in a mixing tank and stir and mix at 500 r / min for 45 min to obtain a mixed material. Step 2: Add pigments and fillers to the mixing tank, continue to stir and mix with the mixed material at 500 r / min for 45 min, and perform sanding after mixing evenly to obtain a fine material with a fineness <15 μm. Step 3: Add adhesion promoter, leveling agent and photoinitiator to the mixing tank, continue to stir and mix with the fine material at 500 r / min for 45 min, and filter to obtain a liquid coating precursor. Step 4: After spraying the coating precursor into a film with a thickness of 120 μm, cure it at a speed of 5 m / min under an ultraviolet irradiation intensity of 500 mW / cm 2 The spraying pressure is 4 bar and the spraying distance is 25 cm to obtain the ultraviolet-cured composite coating.

[0076] Example 4 This example provides an ultraviolet-cured composite coating. The ultraviolet-cured composite coating is obtained by mixing phenolic modified acrylate, polyolefin modified polyurethane acrylate, active diluent, adhesion promoter, leveling agent, dispersant, defoamer, pigment, filler and photoinitiator, followed by spraying and curing; the adhesion grade of the ultraviolet-cured composite coating is 0 level and the pencil hardness is 2H; the insulation resistance of the ultraviolet-cured composite coating after polarization at 1000 V / 60 s > 1 GΩ, and the leakage current after polarization at 5000 V / 60 s < 0.1 mA; After the ultraviolet-cured composite coating is impacted in the vertical direction of 1 kg * 50 cm, bent around a shaft rod with a curvature radius of 0.5 mm, soaked in normal temperature electrolyte for 30 days, soaked in 85 °C electrolyte for 4 h, and stored under neutral salt spray conditions for 2000 h, the adhesion and pencil hardness remain unchanged, and there is no paint peeling, no crack, no bubble, no shedding on the surface, and the insulation resistance and leakage current do not change; After the ultraviolet-cured composite coating is stored at 85 °C and 85% RH for 2000 h, the adhesion and pencil hardness remain unchanged, there is no paint peeling, no crack, no bubble, no shedding on the surface, the surface slightly discolors, the insulation resistance and leakage current do not change, and the bonding strength is 17.8 MPa; After 1000 hours of thermal cycling between -40°C and 85°C, the adhesion and pencil hardness of the ultraviolet-cured composite coating remain unchanged. There is no paint peeling, cracking, bubbling, or flaking on the surface, and the surface only shows slight discoloration. The insulation resistance and leakage current remain unchanged, and the bonding strength is 19.8 MPa.

[0077] In this embodiment, the components and their contents in the ultraviolet-cured composite coating are as follows: Phenolic modified epoxy acrylate: 40 parts by weight; Polybutadiene-styrene modified polyurethane acrylate: 10 parts by weight; Reactive diluent: 30 parts by weight; Adhesion promoter: 2 parts by weight; Leveling agent: 0.3 parts by weight; Dispersant: 0.5 parts by weight; Defoamer: 0.2 parts by weight; Pigment: 2.5 parts by weight; Filler: 0.5 parts by weight; Photoinitiator: 4 parts by weight; The modification process of the phenolic modified epoxy acrylate is as follows: At 40°C, 1 mol of o-cresol novolac epoxy resin is added with 0.3% of benzyltriethylammonium chloride, 500 ppm of 4-methoxyphenol, and 100 ppm of phenothiazine based on the total mass of the substances. Then, 1 mol of acrylic acid or methacrylic acid is added, and continuous bubbling is carried out at 200 mL / min. The mixture is further heated to 80°C and kept warm for 3 hours. When the difference between the acid value in the system and the initial acid value is <5 mg / KOH / g and the epoxy value <0.03, the reaction ends, and the phenolic modified epoxy acrylate is obtained. The modification process of the polybutadiene-styrene modified polyurethane acrylate is as follows: 2.15 mol of toluene diisocyanate and 1 mol of polytetrahydrofuran diol are stirred and reacted at 500 r / min and 65°C for 2 hours. Then, 1 mol of polybutadiene-styrene is added, and the reaction continues for 2 hours. Finally, 2.2 mol of 2-hydroxyethyl methacrylate is added and reacted for 4 hours. When the NCO content in the system is lower than 0.1%, the reaction ends, and the polybutadiene-styrene modified polyurethane acrylate is obtained. The reactive diluent is 10 parts by weight of lauryl methacrylate and 30 parts by weight of isobornyl methacrylate; The adhesion promoter is a monofunctional acid ester modifier with the brand name SR9050; The leveling agent is a polyether silicone copolymer, manufactured by BYK, with the brand name BYK3760; The dispersant has a polymer segment with an amphiphilic molecular structure, which is an acrylic copolymer. The manufacturer is BYK and the grade is BYK-2013; The defoamer is a self-emulsifying defoamer. The manufacturer is BYK and the grade is BYK1799; The pigment is 0.5 parts by weight of phthalocyanine blue and 2 parts by weight of titanium dioxide; The filler includes 0.5 parts by weight of fumed silica; The photoinitiator includes 1 part by weight of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide and 3 parts by weight of 1-hydroxycyclohexyl phenyl ketone.

[0078] This example also provides a method for preparing the ultraviolet-cured composite coating, including the following steps: Step 1: Place phenolic-modified epoxy acrylate, polybutadiene-styrene-modified polyurethane acrylate, active diluent, dispersant, and defoamer in a mixing tank and stir and mix at 1500 r / min for 15 min to obtain a mixed material; Step 2: Add the pigment and filler to the mixing tank, continue to stir and mix with the mixed material at 1500 r / min for 15 min, and perform sanding after mixing evenly to obtain a fine material with a fineness < 15 μm; Step 3: Add the adhesion promoter, leveling agent, and photoinitiator to the mixing tank, continue to stir and mix with the fine material at 1500 r / min for 15 min, and filter to obtain a liquid coating precursor; Step 4: After spraying the coating precursor into a film with a thickness of 120 μm, cure it at a speed of 5 m / min under an ultraviolet irradiation intensity of 500 mW / cm 2 The spraying pressure is 1.5 bar and the spraying distance is 15 cm to obtain the ultraviolet-cured composite coating.

[0079] Comparative Example 1 This comparative example provides an ultraviolet-cured composite coating. The ultraviolet-cured composite coating is obtained by mixing polyolefin-modified polyurethane acrylate, active diluent, adhesion promoter, leveling agent, dispersant, defoamer, pigment, filler, and photoinitiator, followed by spraying and curing; the adhesion grade of the ultraviolet-cured composite coating is 0, and the pencil hardness is B; the insulation resistance of the ultraviolet-cured composite coating after polarization at 1000 V / 60 s > 1 GΩ, and the leakage current after polarization at 5000 V / 60 s < 0.1 mA; After being impacted vertically at 1 kg * 50 cm, bent around a shaft rod with a curvature radius of 0.5 mm, and stored under neutral salt spray conditions for 2000 h, the adhesion and pencil hardness of the composite coating cured by ultraviolet light remain unchanged, and there is no paint peeling, no cracking, no bubbling, and no peeling on the surface, and there is no change in insulation resistance and leakage current; After the composite coating cured by ultraviolet light is immersed in normal temperature electrolyte for 30 days and in 85 °C electrolyte for 4 h, the adhesion is grade 4, and the composite coating cured by ultraviolet light after polarization at 1000 V / 60 s is broken down; After the composite coating cured by ultraviolet light is stored at 85 °C and 85% RH for 2000 h, the adhesion and pencil hardness remain unchanged, there is no paint peeling, no cracking, no bubbling, and no peeling on the surface, the surface slightly changes color, the insulation resistance and leakage current remain unchanged, and the bonding strength is 11.7 MPa; After the composite coating cured by ultraviolet light undergoes 1000 h of thermal cycling from -40 to 85 °C, the adhesion and pencil hardness remain unchanged, there is no paint peeling, no cracking, no bubbling, and no peeling on the surface, the surface slightly changes color, the insulation resistance and leakage current remain unchanged, and the bonding strength is 12.5 MPa.

[0080] In this comparative example, the components and their contents in the composite coating cured by ultraviolet light are as follows: Polybutadiene-modified polyurethane acrylate: 15 parts by weight; Reactive diluent: 35 parts by weight; Adhesion promoter: 3 parts by weight; Leveling agent: 0.3 parts by weight; Dispersant: 2 parts by weight; Defoaming agent: 0.5 parts by weight; Pigment: 6.2 parts by weight; Filler: 18 parts by weight; Photoinitiator: 5 parts by weight; The modification process of the polybutadiene-modified polyurethane acrylate is as follows: 2.15 mol of toluene diisocyanate and 1 mol of polytetrahydrofuran diol are stirred and reacted at 500 r / min and 65 °C for 2 h, then 1 mol of polybutadiene is added and the reaction continues for 2 h, and finally 2.2 mol of 2-hydroxyethyl methacrylate is added and reacted for 4 h. When the NCO content in the system is lower than 0.1%, the reaction ends to obtain the polybutadiene-modified polyurethane acrylate; The reactive diluent is 20 parts by weight of isobornyl acrylate and 15 parts by weight of 4-tert-butylcyclohexyl acrylate; The adhesion promoter is a trifunctional phosphate ester modifier, manufactured by Arkema, with the trade name SR9054; The leveling agent is a polyether silicone copolymer, manufactured by BYK, with the grade of BYK379; The dispersant has a polymer segment with an amphiphilic molecular structure, and its grade is Lencolo 1108; The defoaming agent is a silicone-free defoaming agent, manufactured by Degussa, with the grade of TEGO920; The pigments are 0.2 parts by weight of iron oxide red, 1 part by weight of iron oxide yellow, and 5 parts by weight of titanium dioxide; The fillers include 15 parts by weight of mica powder and 3 parts by weight of zinc phosphomolybdate; The photoinitiators include 3 parts by weight of 1-hydroxycyclohexyl phenyl ketone and 2 parts by weight of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (TPO).

[0081] This comparative example also provides a method for preparing the ultraviolet-cured composite coating, which includes the following steps: Step 1: Put the polybutadiene-modified polyurethane acrylate, active diluent, dispersant, and defoaming agent into a mixing tank and stir and mix them at 800 r / min for 30 min to obtain a mixed material; Step 2: Add the pigments and fillers to the mixing tank, continue to stir and mix them with the mixed material at 800 r / min for 30 min, and then perform sanding after mixing evenly to obtain a fine material with a fineness < 15 μm; Step 3: Add the adhesion promoter, leveling agent, and photoinitiator to the mixing tank, continue to stir and mix them with the fine material at 800 r / min for 30 min, and filter to obtain a liquid coating precursor; Step 4: After spraying the coating precursor into a film with a thickness of 100 μm, cure it at a speed of 5 m / min under an ultraviolet irradiation intensity of 300 mW / cm 2 The spraying pressure is 1.5 bar, and the spraying distance is 15 cm to obtain the ultraviolet-cured composite coating.

[0082] Comparative Example 2 This comparative example provides an ultraviolet-cured composite coating, which is obtained by mixing phenolic-modified acrylate, active diluent, adhesion promoter, leveling agent, dispersant, defoaming agent, pigments, fillers, and photoinitiator, followed by spraying and curing; the adhesion grade of the ultraviolet-cured composite coating is 0, and the pencil hardness is 2H; the insulation resistance of the ultraviolet-cured composite coating after polarization at 1000 V / 60 s > 1 GΩ, and the leakage current after polarization at 5000 V / 60 s < 0.1 mA; After the ultraviolet-cured composite coating is impacted vertically at 1 kg * 50 cm and bent around a shaft rod with a curvature radius of 0.5 mm, cracks occur on the surface; After the composite coating cured by UV is immersed in an electrolyte at room temperature for 30 days, immersed in an electrolyte at 85°C for 4 hours, and stored under neutral salt spray conditions for 2000 hours, the adhesion and pencil hardness remain unchanged, there is no paint exposure, cracks, bubbling, or shedding on the surface, and the insulation resistance and leakage current remain unchanged; After the composite coating cured by UV is stored at 85°C and 85%RH for 2000h, the adhesion and pencil hardness remain unchanged, there is no paint exposure, cracks, bubbling, or shedding on the surface, the surface is slightly discolored, the insulation resistance and leakage current remain unchanged, and the bonding strength is 16.9MPa; After the UV-cured composite coating has been subjected to a cold and hot cycle at -40 to 85°C for 1000 hours, the adhesion and pencil hardness remain unchanged, there is no paint exposure, cracks, bubbles, or peeling on the surface, the surface has slight discoloration, the insulation resistance and leakage current remain unchanged, and the bonding strength is 18.7MPa.

[0083] In this comparative example, the components and the contents of the components in the composite coating cured by ultraviolet light are: Phenolic modified polyurethane acrylate: 15 parts by weight; Active diluent: 35 parts by weight; Adhesion promoter: 3 parts by weight; Leveling agent: 0.3 parts by weight; Dispersant: 2 parts by weight; Defoaming agent: 0.5 parts by weight; Pigment: 6.2 parts by weight; Filler: 18 parts by weight; Photoinitiator: 5 parts by weight; The modification process of the phenolic modified polyurethane acrylate is as follows: 2.0 mol of toluene diisocyanate was added dropwise with 1 mol of polytetrahydrofuran diol, and the mixture was stirred at 500 r / min and 65°C for 2 h. 1 mol of o-cresol resin was added and the reaction was continued for 2 h. Finally, 2.2 mol of hydroxyethyl methacrylate was added and the reaction was continued for 4 h. The reaction was terminated at 65°C when the NCO content of the system was less than 0.1%, thereby obtaining phenolic modified polyurethane acrylate. The active diluent is 20 parts by weight of isobornyl acrylate and 15 parts by weight of 4-tert-butyl cyclohexyl acrylate; The adhesion promoter is a trifunctional phosphate modified substance, the manufacturer is Arkema, and the brand is SR9054; The leveling agent is a polyether siloxane copolymer, manufactured by BYK, with a brand name of BYK379; The dispersant has a polymer segment with an amphiphilic molecular structure, and the brand is Lencolo 1108; The defoamer is a silicone-free defoamer, manufactured by Degussa, with the grade of TEGO920; The pigments are 0.2 parts by weight of iron oxide red, 1 part by weight of iron oxide yellow, and 5 parts by weight of titanium dioxide; The fillers include 15 parts by weight of mica powder and 3 parts by weight of zinc phosphomolybdate; The photoinitiators include 3 parts by weight of 1-hydroxycyclohexyl phenyl ketone and 2 parts by weight of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (TPO).

[0084] This comparative example also provides a method for preparing the ultraviolet-cured composite coating described above, including the following steps: Step 1: Place the phenolic modified polyurethane acrylate, active diluent, dispersant, and defoamer in a mixing tank and stir and mix at 800 r / min for 30 min to obtain a mixed material; Step 2: Add the pigments and fillers to the mixing tank, continue to stir and mix with the mixed material at 800 r / min for 30 min, and after mixing evenly, perform sanding to obtain a fine material with a fineness < 15 μm; Step 3: Add the adhesion promoter, leveling agent, and photoinitiator to the mixing tank, continue to stir and mix with the fine material at 800 r / min for 30 min, and filter to obtain a liquid coating precursor; Step 4: After spraying the coating precursor into a film with a thickness of 100 μm, cure it at a speed of 5 m / min under an ultraviolet irradiation intensity of 300 mW / cm 2 , where the spraying pressure is 1.5 bar and the spraying distance is 15 cm, to obtain the ultraviolet-cured composite coating.

[0085] As Figure 3 This is the surface state diagram of the ultraviolet-cured composite coating described in Comparative Example 2 after the impact resistance test. Cracks appeared on the surface after the impact performance test; Figure 4 This is the surface state diagram of the ultraviolet-cured composite coating described in Comparative Example 2 after the flexural resistance test. Cracks appeared on the surface after the flexural performance test.

[0086] Table 1 shows the components and contents of the ultraviolet-cured composite coatings in Examples 1-4 and Comparative Examples 1-2

[0087] Table 2 shows the performance tests of the ultraviolet-cured composite coatings described in Examples 1-4 and Comparative Examples 1-2

[0088] As can be seen from Table 2, the composite coating cured by ultraviolet in the present invention has a high adhesion grade and high hardness, so it is scratch-resistant and wear-resistant during use. At the same time, the composite coating cured by ultraviolet in the present invention has a high insulation resistance and low leakage current under high pressure, so it has strong insulation. The composite coating cured by ultraviolet in the present invention has strong impact resistance and bending resistance, good corrosion resistance, temperature resistance and salt resistance, and can be used for a long time in extreme environments without aging, peeling and other situations. In Comparative Document 1, phenolic-modified acrylate is not added, and its adhesion grade decreases under high temperature, high humidity and corrosion conditions, and its hardness is low. In Comparative Example 2, polyolefin-modified polyurethane acrylate is not added, and it cracks under impact conditions and after bending.

[0089] The test standard for the adhesion grade in the present invention is the ISO grade, and the test method is: cross-cut method. Use a cross-cut tool to draw a cross-shaped grid with a side length of 1 mm on the coating surface, then stick and peel off with tape, and observe the peeling situation on the coating surface. Among them, the 0-grade standard is: there is no peeling at the grid edge after testing, and the incision edge is completely smooth; The test method for the pencil hardness is: rub the coating surface with pencil leads of different hardnesses (such as HB, H or 2H, etc.) to observe whether there are scratches. The composite coating cured by ultraviolet in the present invention has no scratches after being rubbed with HB, H and / or 2H pencils; The test condition for the impact performance is that a 1 kg heavy object impacts the coating surface at a distance of 50 cm in the vertical direction; The test standard for the bending performance is "GB / T1731-2020", the test standard for salt spray resistance is "GB / T10125-2021", the test standard for high temperature and humidity resistance is "GB / T2423.50-2012", and the test standard for thermal cycling resistance is "GB / T2423.22-2012"; In the electrolyte resistance test, the electrolyte is LB-315, pH 4-6, and the main components are propylene carbonate, ethylene carbonate, ethyl methyl carbonate and lithium hexafluorophosphate.

[0090] From the above, it can be seen that the composite coating cured by ultraviolet described in the present invention has a very wide range of uses and low costs, and has extremely high market prospects.

[0091] The above is only a preferred embodiment of the present invention, and it is not a limitation of the present invention in any other form. Any modification or equivalent change made according to the technical essence of the present invention still belongs to the scope protected by the present invention.

Claims

1. A composite coating cured by ultraviolet light, characterized in that: The composite coating cured by ultraviolet light is obtained by mixing phenolic modified acrylate, polyolefin modified polyurethane acrylate, active diluent, adhesion promoter, leveling agent, dispersant, defoamer, pigment, filler and photoinitiator, and then spraying and curing. The adhesion grade of the composite coating cured by ultraviolet light is 0, and the pencil hardness is HB-2H. The insulation resistance of the composite coating cured by ultraviolet light after polarization at 1000V / 60s is greater than 1GΩ, and the leakage current after polarization at 5000V / 60s is less than 0.1mA. The UV-cured composite coating has no changes in adhesion and pencil hardness after being impacted in a vertical direction of 1kg*50cm, being bent around a shaft with a curvature radius of 0.5mm, being immersed in a room temperature electrolyte for 30 days, being immersed in an electrolyte at 85°C for 4 hours, and being stored in a neutral salt spray condition for 2000 hours. The surface has no paint exposure, no cracks, no bubbling, no shedding, and no changes in insulation resistance and leakage current. After the composite coating cured by UV is stored at 85°C and 85%RH for 2000h, the adhesion and pencil hardness remain unchanged, there is no paint exposure, no cracks, no bubbling, no shedding on the surface, the surface is slightly discolored, the insulation resistance and leakage current remain unchanged, and the bonding strength is 12-20MPa; After the UV-cured composite coating has been subjected to a cold and hot cycle at -40 to 85°C for 1000 hours, the adhesion and pencil hardness remain unchanged, the surface has no paint peeling, no cracks, no bubbles, no falling off, the surface has slight discoloration, the insulation resistance and leakage current remain unchanged, and the bonding strength is 12-20MPa.

2. The UV-cured composite coating according to claim 1, characterized in that: The components and contents of the components in the composite coating cured by ultraviolet light are: Phenolic modified acrylate: 10-40 parts by weight; Polyolefin modified polyurethane acrylate: 5-40 parts by weight; Active diluent: 20-60 parts by weight; Adhesion promoter: 1-8 parts by weight; Leveling agent: 0.1-0.5 parts by weight; Dispersant: 0.1-5 parts by weight; Defoaming agent: 0.1-5 parts by weight; Pigment: 1-20 parts by weight; Filler: 0.5-40 parts by weight; Photoinitiator: 3-6 parts by weight.

3. The UV-cured composite coating according to claim 1, characterized in that: When the thickness of the phenolic modified acrylate is 40 μm, the compressive strength is 6 kV, and when the thickness is 110 μm, the compressive strength is 8-11 kV.

4. The UV-cured composite coating according to claim 1, characterized in that: The phenolic modified acrylate is one or more of phenolic modified epoxy acrylate and phenolic modified polyurethane acrylate.

5. The UV-cured composite coating according to claim 1, characterized in that: The polyolefin in the polyolefin-modified polyurethane acrylate is one or more of polybutadiene, polybutadiene-acrylonitrile and polybutadiene-styrene.

6. A method for preparing a composite coating by UV curing according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1, placing phenolic modified acrylate, polyolefin modified polyurethane acrylate, active diluent, dispersant and defoamer in a mixing tank, stirring and mixing to obtain a mixture; Step 2, adding pigment and filler into the mixing tank, continuing to stir and mix with the mixed material, and sand-grinding after mixing evenly to obtain fine material; Step 3, adding an adhesion promoter, a leveling agent and a photoinitiator into the mixing tank, continuing to stir and mix with the fine material, and filtering to obtain a liquid coating precursor; Step 4: spray the coating precursor into a film and then cure it to obtain the UV-cured composite coating.

7. The preparation method according to claim 6, characterized in that: The fineness of the fine material in step 2 is less than 15 μm.

8. The preparation method according to claim 6, characterized in that: The thickness of the film in step 4 is 80-130 μm.

9. The preparation method according to claim 6, characterized in that: The curing speed in step 4 is 1-20 m / min, the curing method is ultraviolet curing, and the irradiation intensity of the ultraviolet light is 300-500 mW / cm 2 .

10. An insulating coating, characterized in that: The insulating coating is prepared from the composite coating cured by ultraviolet light according to any one of claims 1 to 5.

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