Ultraviolet-cured recoatable composite material as well as preparation method and application thereof

Abstract

The invention discloses an ultraviolet-cured recoatable composite material as well as a preparation method and application thereof, and belongs to the technical field of insulating materials. The composite coating capable of being repeatedly coated is prepared by adding the auxiliaries into the phenolic aldehyde modified acrylate and the polyurethane acrylate and blending, the phenolic aldehyde modified acrylate and the polyurethane acrylate have excellent corrosion resistance, temperature resistance and moisture resistance, and meanwhile, the phenolic aldehyde modified acrylate and the polyurethane acrylate are blended with the reactive diluent with high permeability, so that the recoatability of the material is improved, and the service life of the material is prolonged. And the additives such as the filler and the dispersing agent also increase the roughness of the material and maintain the processability of the material. The recoatable composite coating disclosed by the invention has the advantages that the recoatability of the material is improved by mixing the copolymer and the copolymer by utilizing the compatibility of the copolymer, and the properties such as impact resistance, bending resistance, temperature resistance and salt resistance of the material are greatly improved at the same time by mixing the copolymer and the copolymer with other assistants.

Description

Technical Field

[0001] The present invention relates to the technical field of insulating materials, and particularly relates to an ultraviolet-curable recoatable composite material, a preparation method thereof, and uses thereof. Background Art

[0002] Insulating coatings play a crucial role in the production and application of electronic devices, power systems, and various electrical products. Their main function is to form an effective insulating barrier between different conductive components to prevent accidental current conduction, thereby ensuring the safe and stable operation of the equipment. Insulating coatings are usually prepared by coating on a substrate and then curing. Moreover, the cost of some insulating coatings is relatively high. When the insulating coating is worn or peeled off due to friction or collision of the substrate, the insulating coating needs to be repeatedly coated and cured. Usually, the recoating method is to polish the position where the product needs to be recoated and then spray a layer of recoating paint to solve the problem.

[0003] However, during the repeated coating process of conventional insulating coatings, due to secondary coating, the coating is extremely prone to peeling, resulting in difficulty for the newly coated coating to adhere firmly. When subjected to slight external forces, such as vibration, friction, etc., it is easy to peel off from the substrate surface, thereby greatly reducing the insulation performance and increasing the safety hazards of equipment operation. This is because after the first coating and curing of some thermosetting insulating coatings, the molecular structure undergoes a cross-linking reaction to form a three-dimensional network structure. This structure reduces the chemical activity on the surface of the insulating coating. When recoating, the molecules in the new coating are difficult to effectively interact and penetrate with the molecules of the cured insulating coating, thereby affecting the adhesion between the new coating and the old coating and resulting in poor recoatability. Secondly, after repeated coating, obvious imprints will appear on the coating appearance. These imprints may manifest as uneven color, inconsistent texture, or obvious boundary marks, etc., seriously affecting the appearance quality of the product. For some electronic products with high appearance requirements, such as mobile phones, tablet computers, etc., such appearance defects are unacceptable and directly affect the market competitiveness of the product.

[0004] Therefore, improving the adhesion between the recoated insulating coating and the original insulating coating is an important indicator for measuring the recoatability of insulating coatings. To solve the problem of poor recoatability, non-reactive resins have also been developed and introduced into the system to increase adhesion and recoatability. However, the performance of the material will decline in terms of chemical resistance, electrolyte resistance, etc., or by adding solvents and using the erosion of the solvents to obtain recoatability, which will inevitably bring pollution problems.

[0005] In summary, with the continuous improvement of the performance requirements for insulating coatings in various industries and the increasing demand for repeated coating, the defects such as peeling, obvious imprints on the appearance, weak adhesion, etc. that occur during the repeated coating of conventional insulating coatings, as well as the serious pollution caused by the large amount of solvent use, have become key problems to be solved urgently. Summary of the Invention

[0006] In view of the above problems, the present invention provides an ultraviolet-curable recoatable composite material, a preparation method and a use thereof. A recoatable composite coating is prepared by blending phenolic modified acrylate and polyurethane acrylate with additives. The phenolic modified acrylate and polyurethane acrylate have excellent corrosion resistance, temperature and humidity resistance. At the same time, the two are blended with an active diluent with strong permeability, which improves the recoatability of the material. Additives such as fillers and dispersants also increase the roughness of the material and maintain the processing performance of the material.

[0007] The present invention provides an ultraviolet-curable recoatable composite material, which is prepared by dissolving and mixing phenolic modified acrylate and polyurethane acrylate with additives; the adhesion grade of the ultraviolet-curable recoatable composite material is grade 0, and the adhesion grade after recoating is grade 0; the pencil hardness of the ultraviolet-curable recoatable composite material is 2B-H; the insulation resistance of the composite coating after polarization at 1000V / 60s is >1GΩ, and the leakage current after polarization at 5000V / 60s is <0.1mA; After the ultraviolet-curable recoatable composite material is impacted vertically at 1kg*50cm, bent around a shaft rod with a curvature radius of 0.5mm, soaked in normal temperature electrolyte for 15 days, soaked in 85°C electrolyte for 2h, and stored under neutral salt spray conditions for 1000h, the adhesion and pencil hardness remain unchanged, and there is no paint peeling, cracking, bubbling or peeling on the surface, and the insulation resistance and leakage current do not change; After the ultraviolet-curable recoatable composite material is stored at 85°C and 85%RH for 1000h, the adhesion and pencil hardness remain unchanged, there is no paint peeling, cracking, bubbling or peeling on the surface, the surface slightly changes color, the insulation resistance and leakage current do not change, and the bonding strength is 10-15MPa; After the ultraviolet-curable recoatable composite material undergoes 1000h of thermal cycling at -40 to 85°C, the adhesion and pencil hardness remain unchanged, there is no paint peeling, cracking, bubbling or peeling on the surface, the surface slightly changes color, the insulation resistance and leakage current do not change, and the bonding strength is 15-20MPa; The additives are active diluent, adhesion promoter, leveling agent, dispersant, defoaming agent, wetting agent, pigment, filler and photoinitiator.

[0008] Furthermore, the components and their contents in the ultraviolet-curable recoatable composite material are as follows: Phenolic modified acrylate: 10-30 parts by weight; Polyurethane acrylate: 20-40 parts by weight; Active diluent: 20-60 parts by weight; Adhesion promoter: 1-8 parts by weight; Leveling agent: 0.1 - 2 parts by weight; Dispersing agent: 0.1 - 2 parts by weight; Defoaming agent: 0.1 - 2 parts by weight; Wetting agent: 0.1 - 2 parts by weight; Pigment: 1 - 20 parts by weight; Filler: 0.5 - 30 parts by weight; Photoinitiator: 1 - 8 parts by weight.

[0009] Furthermore, when the thickness of the phenolic modified acrylate is 40 μm, the withstand voltage strength is 6 kV; when the thickness is 110 μm, the withstand voltage strength is 8 - 11 kV.

[0010] Furthermore, the phenolic modified acrylate is one or several of phenolic modified epoxy acrylate and phenolic modified polyurethane acrylate.

[0011] Furthermore, the preparation 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.

[0012] Furthermore, the preparation process of the phenolic modified polyurethane acrylate is as follows: Dropwise add 0.1 - 1 mol of polyol to 2.0 - 2.15 mol of diisocyanate, stir and heat at 300 - 500 r / min to 40 - 85 °C, react for 0.5 - 4 h, then add 0.2 - 2 mol of o-cresol novolac resin, continue to react for 0.5 - 4 h, and 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.

[0013] Furthermore, the preparation process of the polyurethane acrylate is as follows: Stir and react 2.0 - 2.15 mol of diisocyanate with 0.1 - 1 mol of polyol at 100 - 800 r / min and 40 - 85 °C for 0.5 - 4 h, then 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 polyurethane acrylate.

[0014] Further, the glass transition temperature of the polyurethane acrylate is less than room temperature.

[0015] Further, in the preparation process of the phenolic modified polyurethane acrylate and the 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).

[0016] Further, in the preparation process of the phenolic modified polyurethane acrylate and the polyurethane acrylate, the polyol is one or more of polypropylene glycol, polypropylene glycol, polypropylene triol, polycaprolactone diol, polytetrahydrofuran diol, polycarbonate diol, neopentyl glycol adipate isophthalate diol, castor oil, and castor oil derivatives.

[0017] Further, in the preparation process of the phenolic modified polyurethane acrylate and the polyurethane acrylate, the capping agent is one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate.

[0018] Further, the active diluents are all hydrophobic and include one or more of 2-phenoxyethyl acrylate, isobornyl acrylate, isobornyl 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, dimethyl acrylate dipropylene glycol ester, 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.

[0019] Further, the adhesion promoter is one or more of titanate, monofunctional acid ester modifier, trifunctional phosphate ester modifier, 3-acryloxypropyltrimethoxysilane, and tetra-neoalkoxy bis(didecyl phosphite acyloxy)titanate.

[0020] Further, the leveling agent is one or two of polyether silicone copolymer or acrylate copolymer.

[0021] 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 carboxyl group, sulfonic acid group, and amine group; The solventophilic group is a non-polar group, including one or more of long-chain hydrocarbon group and polyether chain segment; The polymer segment includes one or more of acrylic polymers and polyether polymers.

[0022] Further, the density of the dispersant is 0.94 - 1.06 kg / m³.

[0023] Further, the defoamer is one or more of silicone-free defoamer, silicone defoamer, organically modified polysiloxane, and self-emulsifying defoamer.

[0024] Further, the wetting agent is one or two of polyether silicone copolymer or acrylate copolymer.

[0025] 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.

[0026] 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 exchange type rust-inhibitive pigment, magnesium dihydrogen phosphate, and zinc phosphomolybdate.

[0027] 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.

[0028] The present invention provides a method for preparing the ultraviolet-curable recoatable composite material, comprising the following steps: Step 1: Put phenolic modified acrylate, polyurethane acrylate, reactive diluent, dispersant and defoamer into a mixing tank and stir and mix them to obtain a mixed material; Step 2: Add pigment and filler into the mixing tank, continue to stir and mix with the mixed material, and perform sanding after mixing evenly to obtain a fine material; Step 3: Add adhesion promoter, leveling agent, wetting 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-curable recoatable composite material.

[0029] Further, in the step 1, the mass ratio of the phenolic modified acrylate, polyurethane acrylate, reactive diluent, dispersant and defoamer is (10 - 30):(20 - 40):(20 - 60):(0.1 - 2):(0.1 - 2).

[0030] Further, when the thickness of the phenolic modified acrylate in the step 1 is 40 μm, the voltage withstand strength is 6 kV, and when the thickness is 110 μm, the voltage withstand strength is 8 - 11 kV.

[0031] Further, the phenolic modified acrylate in the step 1 is one or more of phenolic modified epoxy acrylate and phenolic modified polyurethane acrylate.

[0032] Further, the preparation 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. When the difference between the acid value in the system and the initial acid value < 5 mg / KOH / g and the epoxy value < 0.03, the reaction ends to obtain the phenolic modified epoxy acrylate.

[0033] Further, the preparation process of the phenolic 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 a capping agent is added and reacted for 2 - 6 h. The reaction is terminated when the NCO content in the system is less than 0.1% at 40 - 85 °C to obtain the phenolic-modified polyurethane acrylate.

[0034] Further, the preparation process of the polyurethane acrylate in step 1 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, 2.0 - 2.2 mol of a capping agent is added and reacted for 2 - 6 h. The reaction is terminated when the NCO content in the system is less than 0.1% to obtain the polyurethane acrylate.

[0035] Further, the glass transition temperature of the polyurethane acrylate in step 1 is less than room temperature.

[0036] Further, in the preparation processes of the phenolic-modified polyurethane acrylate and the 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).

[0037] Further, in the preparation processes of the phenolic-modified polyurethane acrylate and the polyurethane acrylate, the polyol is one or more of polypropylene glycol, polypropylene glycol, polypropylene triol, polycaprolactone diol, polytetrahydrofuran diol, polycarbonate diol, neopentyl glycol adipate isophthalate diol, castor oil, and castor oil derivatives.

[0038] Further, in the preparation processes of the phenolic-modified polyurethane acrylate and the polyurethane acrylate, the capping agent is one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate.

[0039] Furthermore, the reactive diluents in Step 1 are all hydrophobic and include one or more of 2-phenoxyethyl acrylate, isobornyl acrylate, isobornyl 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 triacrylate, dipropylene 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.

[0040] Furthermore, the dispersant in Step 1 is a polymer chain segment with an amphiphilic molecular structure, and the amphiphilic molecular structure contains 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 chain segments; The polymer chain segment includes one or more of acrylic polymers and polyether polymers.

[0041] Furthermore, the density of the dispersant in Step 1 is 0.94 - 1.06 kg / m³.

[0042] Furthermore, the defoamer in Step 1 is one or more of silicone-free defoamers, silicone defoamers, organically modified polysiloxanes, and self-emulsifying defoamers.

[0043] Furthermore, the stirring speed in Step 1 is 500 - 1500 r / min, and the stirring time is 15 - 45 min.

[0044] Furthermore, the mass ratio of the pigment, the filler, and the phenolic modified acrylate in Step 2 is (1 - 20):(0.5 - 30):(10 - 30).

[0045] Furthermore, the pigment in 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.

[0046] Further, the filler in 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 flakes, calcium ion exchange type rust preventive pigment, magnesium dihydrogen phosphate, and zinc phosphomolybdate.

[0047] Further, the speed of continuous stirring in step 2 is 500 - 1500 r / min, and the time of continuous stirring is 15 - 45 min.

[0048] Further, the fineness of sanding in step 2 is < 15 μm.

[0049] Further, the mass ratio of the adhesion promoter, the leveling agent, the wetting agent, the photoinitiator to the phenolic modified acrylate in step 3 is (1 - 8):(0.1 - 2):(0.1 - 2):(1 - 8):(10 - 30).

[0050] Further, the adhesion promoter in step 3 is one or more of titanate, monofunctional acid ester modifier, trifunctional phosphate ester modifier, 3 - acryloxypropyltrimethoxysilane, and tetraalkoxy bis(didecylphosphite) titanate.

[0051] Further, the leveling agent in step 3 is one or two of polyether silicone copolymer or acrylate copolymer.

[0052] Further, the wetting agent in step 3 is one or two of polyether silicone copolymer or acrylate copolymer.

[0053] Further, the photoinitiator in step 3 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.

[0054] Further, the speed of continuous stirring in step 3 is 500 - 1500 r / min, and the time of continuous stirring is 15 - 45 min.

[0055] Further, in the step 4, the spraying pressure is 1.5 - 4 bar, and the spraying distance is 15 - 25 cm.

[0056] Further, in the step 4, the thickness of the film is 80 - 130 μm.

[0057] 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 。

[0058] The present invention also provides an electrical insulation outer layer coating, and the electrical insulation outer layer coating is prepared from the ultraviolet-cured recoatable composite material.

[0059] Advantages of the present invention: 1. By blending phenolic modified acrylate and polyurethane acrylate, in addition to their excellent insulation properties and mechanical properties, the phenolic structural unit and acrylate group in the phenolic modified acrylate, as well as the urethane bond and acrylate double bond in the polyurethane acrylate molecule, have high reactivity. The polyurethane acrylate resin with a glass transition temperature lower than room temperature has strong segmental movement ability, enabling a certain degree of interpenetrating crosslinking between the liquid coating and the outermost layer of the coating, thereby enhancing the adhesion between the new coating and the old coating and improving the recoatability; 2. The present invention also cures the ultraviolet-cured recoatable composite material on the substrate by ultraviolet curing. The ultraviolet curing method can form a coating with a certain hardness and wear resistance in a short time. By selecting a hydrophobic reactive diluent, the adverse effect of humidity on the coating is further reduced. At the same time, during recoating, the curing process of the new coating will not cause excessive swelling or damage to the old coating, maintaining the stability of the coating system. Under ultraviolet irradiation, the acrylate double bond rapidly undergoes a free radical polymerization reaction to quickly form a dense coating structure, and this curing process is relatively mild, having less impact on the old coating and being beneficial for recoating; 3. The phenolic modified acrylate and polyurethane acrylate in the present invention are blended with a liquid reactive diluent, and the microphase separation between the phenolic modified acrylate and polyurethane acrylate and the hydrophobic reactive diluent is utilized to increase the roughness of the ultraviolet-cured recoatable composite material, enhancing the adhesion of the ultraviolet-cured recoatable composite material during recoating. At the same time, a fixed amount of inorganic filler is added in the present invention to further increase the roughness of the coating, further enhancing the adhesion of the ultraviolet-cured recoatable composite material during recoating. The introduction of a leveling agent for the photocurable modified acrylate provides better leveling performance for the coating without affecting the recoatability. Specific embodiments

[0060] The invention will be described in detail below in conjunction with embodiments: The present invention provides an ultraviolet-curable recoatable composite material, its preparation method and uses. Phenol-formaldehyde modified acrylate and polyurethane acrylate with excellent properties are mixed. By virtue of the compatibility between the copolymers, the advantages of both are reflected in the recoatable composite coating of the present invention. Other additives are mixed with the two to improve the recoatability of the material, and at the same time, its impact resistance, bending resistance, temperature resistance, salt resistance and other properties are greatly improved.

[0061] Example 1 This example provides an ultraviolet-curable recoatable composite material, which is prepared by dissolving and mixing phenol-formaldehyde modified acrylate and polyurethane acrylate and adding additives; the adhesion grade of the ultraviolet-curable recoatable composite material is grade 0, and the adhesion grade after recoating is grade 0; the pencil hardness of the ultraviolet-curable recoatable composite material is 2B; the insulation resistance of the composite coating after polarization at 1000V / 60s > 1GΩ, and the leakage current after polarization at 5000V / 60s < 0.1mA; After the ultraviolet-curable recoatable composite material is impacted vertically at 1kg * 50cm, bent around a shaft rod with a curvature radius of 0.5mm, immersed in normal-temperature electrolyte for 15 days, immersed in 85°C electrolyte for 2h, and stored under neutral salt spray conditions for 1000h, the adhesion and pencil hardness remain unchanged, and there is no paint peeling, no cracking, no bubbling, no falling off on the surface, and the insulation resistance and leakage current do not change; After the ultraviolet-curable recoatable composite material is stored at 85°C and 85% RH for 1000h, the adhesion and pencil hardness remain unchanged, there is no paint peeling, no cracking, no bubbling, no falling off on the surface, the surface slightly changes color, the insulation resistance and leakage current do not change, and the bonding strength is 11.3MPa; After the ultraviolet-curable recoatable composite material undergoes 1000h of thermal cycling at -40 to 85°C, the adhesion and pencil hardness remain unchanged, there is no paint peeling, no cracking, no bubbling, no falling off on the surface, the surface slightly changes color, the insulation resistance and leakage current do not change, and the bonding strength is 16.5MPa; The additives are reactive diluents, adhesion promoters, leveling agents, dispersants, defoamers, wetting agents, pigments, fillers and photoinitiators.

[0062] In this example, the components and their contents in the ultraviolet-curable recoatable composite material are as follows: Phenol-formaldehyde modified polyurethane acrylate: 10 parts by weight; Polytetrahydrofuran ether polyurethane acrylate: 20 parts by weight; Reactive diluent: 35 parts by weight; Adhesion promoter: 3 parts by weight; Leveling agent: 0.2 parts by weight; Dispersant: 0.8 parts by weight; Defoaming agent: 0.5 parts by weight; Wetting agent: 0.3 parts by weight; Pigment: 5.2 parts by weight; Filler: 20 parts by weight; Photoinitiator: 5 parts by weight; The preparation 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 preparation process of the polytetrahydrofuran ether polyurethane acrylate is: 2.15 mol of toluene diisocyanate and 1 mol of polytetramethylene glycol were stirred at 500 r / min and 65° C. for 2 h, and then 2.2 mol of hydroxyethyl methacrylate was added for 4 h. When the NCO content of the system was less than 0.1%, the reaction was terminated to obtain the polytetramethylene ether polyurethane acrylate; The active diluent is 20 parts by weight of isobornyl methacrylate and 15 parts by weight of isodecyl acrylate; The adhesion promoter is a trifunctional phosphate modified substance, the manufacturer is Arkema, and the brand is SR9054; The leveling agent is a photopolymerizable polyether siloxane copolymer, the manufacturer is TEGO, the brand is TEGO RAD2250; The dispersant has 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 wetting agent is a polyether siloxane copolymer, the manufacturer is TEGO, the brand is TEGO WET 270; The pigment is 0.2 parts by weight of red iron oxide, 1 part by weight of yellow iron oxide and 4 parts by weight of titanium dioxide; The filler includes 20 parts by weight of mica powder; 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).

[0063] This embodiment also provides a method for preparing the UV-curable recoatable composite material, comprising the following steps: Step 1: Place phenolic modified polyurethane acrylate, polytetrahydrofuran ether polyurethane acrylate, reactive 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 pigment and filler to the mixing tank, continue to stir and mix with the mixed material at 800 r / min for 30 min, and perform sanding after mixing evenly to obtain a fine material with a fineness < 15 μm; Step 3: Add adhesion promoter, leveling agent, wetting 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 , the spraying pressure is 1.5 bar, and the spraying distance is 15 cm to obtain the ultraviolet-cured recoatable composite material.

[0064] Example 2 This example provides an ultraviolet-cured recoatable composite material, which is prepared by dissolving and mixing phenolic modified acrylate and polyurethane acrylate with additives; the adhesion grade of the ultraviolet-cured recoatable composite material is grade 0, and the adhesion grade after recoating is grade 0; the pencil hardness of the ultraviolet-cured recoatable composite material is HB; the insulation resistance of the 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 recoatable composite material is impacted vertically at 1 kg * 50 cm, bent around a shaft rod with a curvature radius of 0.5 mm, immersed in normal temperature electrolyte for 15 days, immersed in 85 °C electrolyte for 2 h, and stored under neutral salt spray conditions for 1000 h, the adhesion and pencil hardness remain unchanged, and there is no paint peeling, no crack, no bubbling, no shedding on the surface, and the insulation resistance and leakage current do not change; After the ultraviolet-cured recoatable composite material is stored at 85 °C and 85% RH for 1000 h, the adhesion and pencil hardness remain unchanged, there is no paint peeling, no crack, no bubbling, no shedding on the surface, the surface slightly changes color, the insulation resistance and leakage current do not change, and the bonding strength is 11.9 MPa; After the ultraviolet-cured recoatable composite material 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, no shedding on the surface, the surface slightly changes color, the insulation resistance and leakage current do not change, and the bonding strength is 17.2 MPa; The auxiliary agents are reactive diluents, adhesion promoters, leveling agents, dispersants, defoamers, wetting agents, pigments, fillers, and photoinitiators.

[0065] In this embodiment, the components and their contents in the ultraviolet-curable recoatable composite material are as follows: Phenolic modified epoxy acrylate: 10 parts by weight; Polycarbonate polyurethane acrylate: 18 parts by weight; Reactive diluent: 30 parts by weight; Adhesion promoter: 5 parts by weight; Leveling agent: 0.3 parts by weight; Dispersant: 1 part by weight; Defoamer: 0.5 parts by weight; Wetting agent: 0.2 parts by weight; Pigment: 5.5 parts by weight; Filler: 27 parts by weight; Photoinitiator: 2.5 parts by weight; The preparation process of the phenolic 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 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 to obtain the phenolic modified epoxy acrylate; The preparation process of the polycarbonate polyurethane acrylate is as follows: React 2.15 mol of toluene diisocyanate with 1 mol of polycarbonate diol by stirring at 500 r / min and 65°C for 2 h. Then 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 to obtain the polycarbonate polyurethane acrylate; The reactive diluent is 30 parts by weight of isobornyl acrylate; The adhesion promoter is titanate; The leveling agent is a photopolymerizable polyether silicone copolymer, manufactured by Degussa, with the product number TEGO RAD2100; The dispersant has a polymer chain segment with an amphiphilic molecular structure, and the product number is Lencolo 1108; The defoamer is a silicone-free defoamer, manufactured by Degussa, with the product number TEGO920; The wetting agent is an acrylate copolymer, manufactured by BYK, with the product number DISPERBYK2055; The pigment is 0.5 parts 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).

[0066] This example also provides a method for preparing the ultraviolet-curable recoatable composite material, which includes the following steps: Step 1: Place phenolic-modified epoxy acrylate, polycarbonate 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 pigment and filler to the mixing tank, continue to stir and mix 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, wetting 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 The spraying pressure is 1.5 bar, and the spraying distance is 15 cm to obtain the ultraviolet-curable recoatable composite material.

[0067] Example 3 This example provides an ultraviolet-curable recoatable composite material, which is prepared by dissolving and mixing phenolic-modified acrylate and polyurethane acrylate with additives; the adhesion grade of the ultraviolet-curable recoatable composite material is 0, and the adhesion grade after recoating is 0; the pencil hardness of the ultraviolet-curable recoatable composite material is B; the insulation resistance of the composite coating after polarization at 1000 V / 60 s is > 1 GΩ, and the leakage current after polarization at 5000 V / 60 s is < 0.1 mA; After the ultraviolet-curable recoatable composite material 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 15 days, soaked in 85°C electrolyte for 2 h, and stored under neutral salt spray conditions for 1000 h, the adhesion and pencil hardness remain unchanged, and there is no paint peeling, no cracking, no bubbling, no shedding on the surface, and there is no change in the insulation resistance and leakage current; After the ultraviolet-curable recoatable composite material is stored at 85 °C and 85% RH for 1000 h, 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 10.8 MPa; After the ultraviolet-curable recoatable composite material undergoes 1000 h of thermal cycling between -40 °C and 85 °C, both 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 15.9 MPa; The auxiliary agents are reactive diluents, adhesion promoters, leveling agents, dispersants, defoamers, wetting agents, pigments, fillers and photoinitiators.

[0068] In this embodiment, the components and their contents in the ultraviolet-curable recoatable composite material are as follows: Phenol-formaldehyde modified epoxy acrylate: 10 parts by weight; Polycarbonate polyurethane acrylate: 18 parts by weight; Polytetrahydrofuran ether polyurethane acrylate: 10 parts by weight; Reactive diluent: 20 parts by weight; Adhesion promoter: 5 parts by weight; Leveling agent: 0.3 parts by weight; Dispersant: 1 part by weight; Defoamer: 0.5 parts by weight; Wetting agent: 0.2 parts by weight; Pigment: 5.5 parts by weight; Filler: 27 parts by weight; Photoinitiator: 2.5 parts by weight; The preparation process of the phenol-formaldehyde 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 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 is added and bubbled continuously at 200 mL / min. The temperature is continued to be raised to 80 °C and held 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 < 0.03, the reaction ends to obtain the phenol-formaldehyde modified epoxy acrylate; The preparation process of the polycarbonate polyurethane acrylate is as follows: 2.15 mol of toluene diisocyanate and 1 mol of polycarbonate diol were stirred at 500 r / min and 65° C. for 2 hours, and then 2.2 mol of hydroxyethyl methacrylate was added for 4 hours. When the NCO content of the system was less than 0.1%, the reaction was terminated to obtain the polycarbonate polyurethane acrylate; The preparation process of the polytetrahydrofuran ether polyurethane acrylate is: 2.15 mol of toluene diisocyanate and 1 mol of polytetramethylene glycol were stirred at 500 r / min and 65° C. for 2 h, and then 2.2 mol of hydroxyethyl methacrylate was added for 4 h. When the NCO content of the system was less than 0.1%, the reaction was terminated to obtain the polytetramethylene ether polyurethane acrylate; The active diluent is 20 parts by weight of isobornyl acrylate; The adhesion promoter is a trifunctional phosphate modified substance, the manufacturer is Arkema, and the brand is SR9051; The leveling agent is a photopolymerizable polyether siloxane copolymer, the manufacturer is TEGO, the brand is TEGO RAD2200; The dispersant has 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 wetting agent is a polyether siloxane copolymer, the manufacturer is TEGO, the brand is TEGO WET 280; The pigment is 0.5 parts by weight of phthalocyanine blue and 5 parts by weight of titanium dioxide; The filler comprises 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).

[0069] This embodiment also provides a method for preparing the UV-curable recoatable composite material, comprising the following steps: Step 1, placing phenolic modified epoxy acrylate, polycarbonate polyurethane acrylate, polytetramethylene ether polyurethane acrylate, active 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: Add the adhesion promoter, leveling agent, wetting agent, and photoinitiator into the mixing tank, and continue to stir and mix with the fine material at 800 r / min for 30 min, then filter to obtain the 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 4 bar, and the spraying distance is 25 cm to obtain the ultraviolet-curable recoatable composite material.

[0070] Comparative Example 1 This comparative example provides an ultraviolet-curable recoatable composite material, which is prepared by dissolving and mixing polyurethane acrylate with additives; the adhesion grade of the ultraviolet-curable recoatable composite material is 0, and the adhesion grade after recoating is 0; the pencil hardness of the ultraviolet-curable recoatable composite material is 3B; the insulation resistance of the 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-curable recoatable composite material is impacted vertically at 1 kg * 50 cm and bent around a rod with a curvature radius of 0.5 mm, the adhesion and pencil hardness remain unchanged, and there is no paint peeling, no crack, no bubbling, and no shedding on the surface, and the insulation resistance and leakage current do not change; After being immersed in the normal-temperature electrolyte for 7 days, the adhesion grades all become 3, and the surface has bubbling and shedding; After being immersed in the 85°C electrolyte for 2 h, the surface has severe bubbling, and the insulation resistance and breakdown voltage are greatly reduced; After being stored under neutral salt spray conditions for 1000 h, the adhesion grade becomes 5, the surface has severe bubbling and shedding, and the insulation resistance and breakdown voltage do not meet the requirements; After the ultraviolet-curable recoatable composite material is stored at 85°C and 85% RH for 1000 h, the adhesion grade becomes 3, there is no paint peeling, no crack, no bubbling, and no shedding on the surface, the surface has severe color change, and the insulation resistance and leakage current do not change; After the ultraviolet-curable recoatable composite material 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 shedding on the surface, the surface has slight color change, the insulation resistance and leakage current do not change, and the bonding strength is 13.5 MPa; The additives are reactive diluent, adhesion promoter, leveling agent, dispersant, defoamer, wetting agent, pigment, filler, and photoinitiator.

[0071] In this comparative example, the components and their contents in the ultraviolet-curable recoatable composite material are as follows: Polytetramethylene ether polyurethane acrylate: 20 parts by weight; Active diluent: 35 parts by weight; Adhesion promoter: 3 parts by weight; Leveling agent: 0.2 parts by weight; Dispersant: 0.8 parts by weight; Defoaming agent: 0.5 parts by weight; Wetting agent: 0.3 parts by weight; Pigment: 5.2 parts by weight; Filler: 20 parts by weight; Photoinitiator: 5 parts by weight; The preparation process of the polytetrahydrofuran ether polyurethane acrylate is: 2.15 mol of toluene diisocyanate and 1 mol of polytetramethylene glycol were stirred at 500 r / min and 65° C. for 2 h, and then 2.2 mol of hydroxyethyl methacrylate was added for 4 h. When the NCO content of the system was less than 0.1%, the reaction was terminated to obtain the polytetramethylene ether polyurethane acrylate; The active diluent is 20 parts by weight of isobornyl methacrylate and 15 parts by weight of isodecyl 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 silicon-free defoamer, manufactured by Digo, with a brand name of TEGO920; The wetting agent is a polyether siloxane copolymer, the manufacturer is TEGO, the brand is TEGO WET 270; The pigment is 0.2 parts by weight of red iron oxide, 1 part by weight of yellow iron oxide and 4 parts by weight of titanium dioxide; The filler includes 20 parts by weight of mica powder; 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).

[0072] This comparative example also provides a method for preparing the UV-curable recoatable composite material, comprising the following steps: Step 1, placing polytetramethylene ether polyurethane acrylate, active 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: Add pigments and fillers into the mixing tank, and continue to stir and mix with the mixture at 800 r / min for 30 min. After mixing evenly, perform sanding to obtain a fine material with a fineness < 15 μm; Step 3: Add an adhesion promoter, a leveling agent, a wetting agent, and a photoinitiator into the mixing tank, and continue to stir and mix with the fine material at 800 r / min for 30 min. Filter to obtain a liquid paint precursor; Step 4: After spraying the paint 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-curable recoatable composite material.

[0073] Comparative Example 2 This comparative example provides an ultraviolet-curable recoatable composite material, which is prepared by dissolving and mixing phenolic modified acrylate with additives; the adhesion grade of the ultraviolet-curable recoatable composite material is 0 grade, and the adhesion grade after recoating is 5 grade; the pencil hardness of the ultraviolet-curable recoatable composite material is H; the insulation resistance of the 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-curable recoatable composite material is impacted vertically at 1 kg * 50 cm, there are microcracks on the surface; After being bent around a shaft rod with a curvature radius of 0.5 mm, soaked in normal-temperature electrolyte for 15 days, soaked in 85 °C electrolyte for 2 h, and stored under neutral salt spray conditions for 1000 h, the adhesion and pencil hardness remain unchanged, and there is no paint peeling, no cracking, no bubbling, no peeling on the surface, and the insulation resistance and leakage current do not change; After the ultraviolet-curable recoatable composite material is stored at 85 °C and 85% RH for 1000 h, the adhesion and pencil hardness remain unchanged, there is no paint peeling, no cracking, no bubbling, no peeling on the surface, the surface has slight discoloration, the insulation resistance and leakage current do not change, and the bonding strength is 12.3 MPa; After the ultraviolet-curable recoatable composite material 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, no peeling on the surface, the surface has slight discoloration, the insulation resistance and leakage current do not change, and the bonding strength is 18.6 MPa; The additives are reactive diluents, adhesion promoters, leveling agents, dispersants, defoamers, wetting agents, pigments, fillers, and photoinitiators.

[0074] In this comparative example, the components and their contents in the ultraviolet-curable recoatable composite material are as follows: Phenolic modified epoxy acrylate: 10 parts by weight; Reactive diluent: 20 parts by weight; Adhesion promoter: 5 parts by weight; Leveling agent: 0.3 parts by weight; Dispersant: 1 part by weight; Defoaming agent: 0.5 parts by weight; Wetting agent: 0.2 parts by weight; Pigment: 5.5 parts by weight; Filler: 27 parts by weight; Photoinitiator: 2.5 parts by weight; The preparation process of the phenolic 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 hold for 3 h. When the difference between the acid value in the system and the initial acid value < 5 mg / KOH / g and the epoxy value < 0.03, the reaction ends to obtain the phenolic modified epoxy acrylate; The reactive diluent is 20 parts by weight of isobornyl acrylate; The adhesion promoter is a titanate; The leveling agent is a polyether silicone copolymer, manufactured by BYK, with the product number BYK379; The dispersant has a polymer chain segment with an amphiphilic molecular structure, and the product number is Lencolo 1108; The defoaming agent is a silicone-free defoaming agent, manufactured by Degussa, with the product number TEGO920; The wetting agent is a polyether silicone copolymer, manufactured by Degussa, with the product number TEGO WET 270; The pigment is 0.5 parts 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).

[0075] This comparative example also provides a preparation method of the ultraviolet-curable recoatable composite material, including the following steps: Step 1: Place the phenolic modified epoxy acrylate, reactive diluent, dispersant, and defoaming agent in a mixing tank and stir and mix at 800 r / min for 30 min to obtain a mixed material; Step 2: Add pigments and fillers into the mixing tank, continue to stir and mix with the mixture at 800 r / min for 30 min, and then perform sand grinding after uniform mixing to obtain a fine material with a fineness < 15 μm; Step 3: Add an adhesion promoter, a leveling agent, a wetting agent, and a photoinitiator into 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 The spraying pressure is 4 bar, and the spraying distance is 25 cm to obtain the ultraviolet-cured recoatable composite material.

[0076] Table 1 shows the components and contents of the ultraviolet-cured recoatable composite materials in Examples 1-3 and Comparative Examples 1-2 of this embodiment

[0077] Table 2 shows the performance tests of the ultraviolet-cured recoatable composite materials in Examples 1-3 and Comparative Examples 1-2 of this embodiment

[0078] As shown in Tables 1 and 2, the ultraviolet-cured recoatable composite material in the present invention has a high adhesion grade, high hardness, good insulation, and good chemical resistance, heat and cold resistance, and salt spray resistance. At the same time, after chemical resistance, heat and cold resistance, and salt spray tests, the adhesion, mechanical properties, and insulation are not affected. The ultraviolet-cured recoatable composite material after high temperature and high humidity and thermal cycling has high bond strength, can meet the adhesion requirements after repeated coating, and the insulation, mechanical properties, chemical resistance, temperature and humidity resistance, and salt spray resistance are not affected, and no obvious marks will appear. However, in Comparative Example 1 and Comparative Example 2, phenolic-modified acrylate and polyurethane acrylate are not added, and the adhesion decreases significantly.

[0079] 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 make a cross-shaped grid with a size of 1 mm on the surface of the coating, then stick and peel off with tape, and observe the peeling situation on the surface of the coating. Among them, the 0-grade standard is: there is no peeling at the edge of the grid after the test, and the incision edge is completely smooth; The test method for the adhesion grade after recoating is: repeat the coating of the ultraviolet-cured recoatable composite material on the upper layer of the composite material in the same spraying method and curing method; The test method for the pencil hardness is as follows: The pencil cores with different hardnesses (such as HB, H or 2H) are rubbed on the surface of the coating, and it is observed whether there are scratches. There are no scratches on the composite coating in the present invention after being rubbed by HB, H and / or 2H pencils; The test condition for the impact performance is that a 1 kg heavy object impacts the surface of the coating 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 shock resistance is "GB / T2423.22 - 2012"; In the electrolyte resistance test, the electrolyte is LB - 315, with a pH of 4 - 6, and the main components are propylene carbonate, ethylene carbonate, ethyl methyl carbonate and lithium hexafluorophosphate.

[0080] As can be seen from the above, the ultraviolet - curable recoatable composite material described in the present invention has a very wide range of applications, low cost, and extremely high market prospects.

[0081] The above - mentioned are only the preferred embodiments of the present invention, and do not impose any other form of limitation on the present invention. Any modification or equivalent change made based on the technical essence of the present invention still falls within the scope claimed by the present invention.

Claims

1. A UV-curable recoatable composite material, characterized in that: The UV-curable recoatable composite material is prepared by adding an auxiliary agent to dissolve and mix phenolic modified acrylate and polyurethane acrylate; the adhesion grade of the UV-curable recoatable composite material is 0, and the adhesion grade after recoating is 0; the pencil hardness of the UV-curable recoatable composite material is 2B-H; the insulation resistance of the composite coating 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-curable recoatable composite material has unchanged adhesion and pencil hardness after being impacted in a vertical direction of 1kg*50cm, bent around a shaft with a curvature radius of 0.5mm, immersed in a room temperature electrolyte for 15 days, immersed in an electrolyte at 85°C for 2 hours, and stored in a neutral salt spray condition for 1000 hours, and has no paint exposure, cracks, bubbles, or shedding on the surface, and no changes in insulation resistance and leakage current; After the UV-curable recoatable composite material is stored at 85°C and 85% RH for 1000 hours, 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 10-15MPa; After the UV-curable recoatable composite material 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 exposure, no cracks, no bubbling, no shedding, the surface has slight discoloration, the insulation resistance and leakage current remain unchanged, and the bonding strength is 15-20MPa; The auxiliary agents are active diluent, adhesion promoter, leveling agent, dispersant, defoamer, wetting agent, pigment, filler and photoinitiator.

2. The UV-curable recoatable composite material according to claim 1, characterized in that: The components and contents of the components in the UV-curable recoatable composite material are: Phenolic modified acrylate: 10-30 parts by weight; Polyurethane acrylate: 20-40 parts by weight; Active diluent: 20-60 parts by weight; Adhesion promoter: 1-8 parts by weight; Leveling agent: 0.1-2 parts by weight; Dispersant: 0.1-2 parts by weight; Defoaming agent: 0.1-2 parts by weight; Wetting agent: 0.1-2 parts by weight; Pigment: 1-20 parts by weight; Filler: 0.5-30 parts by weight; Photoinitiator: 1-8 parts by weight.

3. The UV-curable recoatable composite material 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.

4. The UV-curable recoatable composite material according to claim 1, characterized in that: The active diluents are all hydrophobic, including 2-phenoxyethyl acrylate, isobornyl acrylate, isobornyl methacrylate, 4-tert-butyl cyclohexyl acrylate, 4-tert-butyl cyclohexyl methacrylate, isooctyl acrylate, isooctyl methacrylate, isodecyl acrylate, isodecyl methacrylate, lauryl acrylate, lauryl methacrylate, octadecyl acrylate, octadecyl methacrylate, bisphenol fluorene diacrylate, ethoxylated bisphenol fluorene diacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, tripropylene glycol diacrylate, One or more of acrylate, dipropylene glycol diacrylate, 1,3-propylene glycol dimethacrylate, dipropylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tricyclodecane dimethanol diacrylate, tricyclodecane dimethanol dimethacrylate, diallyl isocyanuric acid, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, ethoxylated trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, isocyanuric acid triacrylate, pentaerythritol triacrylate and dipentaerythritol hexaacrylate.

5. The UV-curable recoatable composite material according to claim 1, characterized in that: The filler includes one or more of mica powder, barium sulfate, kaolin, talc, silica powder, alumina, fumed silica, polytetrafluoroethylene wax powder, zinc phosphate, glass flakes, calcium ion exchange anti-rust pigment, magnesium dihydrogen phosphate and zinc phosphomolybdate.

6. The UV-curable recoatable composite material according to claim 1, characterized in that: The photoinitiator includes one or more of 2-hydroxy-2-methylpropiophenone, 1-hydroxycyclohexyl phenyl ketone, diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, phenyl bis (2,4,6-trimethylbenzoyl) phosphine oxide, 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-morpholino)-1-[4-(methylthio)phenyl]-1-propanone.

7. A method for preparing the UV-curable recoatable composite material according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1, placing phenolic modified acrylate, 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, a wetting 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: spraying the coating precursor into a film and then curing it to obtain the UV-curable recoatable composite material.

8. The preparation method according to claim 7, characterized in that: The spraying pressure in step 4 is 1.5-4 bar, and the spraying distance is 15-25 cm.

9. The preparation method according to claim 7, characterized in that: The thickness of the film in step 4 is 80-130 μm.

10. An electrical insulation outer coating, characterized in that: The electrical insulation outer coating is prepared from the UV-curable recoatable composite material according to any one of claims 1 to 6.

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