Bio-based powder coating with insulation, heat insulation and fingerprint resistance and preparation method thereof

Abstract

The invention discloses a bio-based powder coating with insulation, heat insulation and fingerprint resistance and a preparation method of the bio-based powder coating, and belongs to the technical field of powder coatings. The powder coating is prepared from the following components in parts by weight: 439 to 593 parts of modified bio-based epoxy resin, 20 to 28 parts of dicyandiamide, 55 to 65 parts of hydroxyl polyester resin, 4 to 8 parts of isocyanate, 0.3 to 0.8 part of acrylic acid, 40 to 60 parts of modified glass beads, 3 to 8 parts of glass fibers, 7 to 15 parts of talcum powder, 0.3 to 0.8 part of thermal expansion agent, 20 to 40 parts of pigment, 2 to 4 parts of flatting agent and 0.5 to 1.5 parts of benzoin. The powder coating has the advantages of good insulation performance, heat insulation performance, fingerprint resistance and the like, and can effectively solve the problems of the powder coating in the prior art.

Description

Technical Field

[0001] The present invention belongs to the technical field of powder coatings, and particularly relates to a bio-based powder coating with insulation, heat insulation and fingerprint resistance properties and a preparation method thereof. Background Art

[0002] Powder coatings are solvent-free solid coatings, which are coated on the surface of objects by methods such as electrostatic spraying and fluidized bed, and form a coating after heating and curing. Compared with traditional liquid coatings, it has the characteristics of environmental protection, high efficiency and excellent performance. Powder coatings are mainly prepared by mixing, pressing, crushing, grinding and sieving resin, curing agent, pigment / filler and additives to obtain powder coatings. As the main film-forming substance, the resin determines the basic properties of the coating; powder coatings are generally adsorbed on the surface of workpieces by electrostatic spraying, and then the workpieces are sent into an oven, and the powder is cured into a film after heating.

[0003] Powder coatings are gradually replacing organic solvent-based coatings with their advantages of economy, environmental protection, high efficiency and excellent performance, and becoming an important development direction in the coating industry. With the expansion of the powder coating market, the requirements for its performance are also getting higher and higher. Most of the existing powder coatings have single functions and do not have heat insulation and fingerprint elimination properties, which limits their application in special fields. Summary of the Invention

[0004] In view of the above deficiencies in the prior art, the present invention provides a bio-based powder coating with insulation, heat insulation and fingerprint resistance properties and a preparation method thereof. The powder coating has the advantages of good insulation performance, heat insulation performance and fingerprint resistance performance, and can effectively solve the problems existing in the powder coatings in the prior art.

[0005] To achieve the above object, the technical solution adopted by the present invention to solve its technical problems is: A bio-based powder coating with insulation, heat insulation and fingerprint resistance properties, comprising the following components in parts by weight: 439-593 parts of modified bio-based epoxy resin, 20-28 parts of dicyandiamide, 55-65 parts of hydroxyl polyester resin, 4-8 parts of isocyanate, 0.3-0.8 parts of acrylic acid, 40-60 parts of modified glass microspheres, 3-8 parts of glass fiber, 7-15 parts of talcum powder, 0.3-0.8 parts of thermal expander, 20-40 parts of pigment, 2-4 parts of leveling agent, 0.5-1.5 parts of benzoin.

[0006] Further, the preparation method of the modified bio-based epoxy resin is as follows: Mix ethanol and water, adjust the pH value of the mixed solution to 4-5, dropwise add a silane coupling agent thereto, react at 4-30 °C under stirring conditions for 1.5-3 h to obtain a hydrolyzed solution of the silane coupling agent; Under nitrogen protection conditions, heat the bio-based epoxy resin to 75-85 °C, and then dropwise add the hydrolyzed solution of the silane coupling agent thereto under stirring conditions, stir and react, and after the reaction is completed, remove the solvent by rotary evaporation to obtain the modified bio-based epoxy resin.

[0007] Further, the mass ratio of the silane coupling agent, ethanol and water is 8-12:75-85:8-12; the mass ratio of the bio-based epoxy resin to the silane coupling agent is 100:1-2.

[0008] Further, the bio-based epoxy resin includes itaconic acid-based epoxy resin and cardanol-based epoxy resin, and the silane coupling agent is KH560.

[0009] Further, the isocyanate is triphenylmethane triisocyanate.

[0010] Further, the preparation method of the modified glass microspheres is as follows: (1) Under ice-water bath conditions, mix ethanol and acetylacetone, and dropwise add tetrabutyl titanate thereto to obtain a mixed solution, and then dropwise add an aqueous solution containing ammonia to adjust the pH of the mixed solution to 3-4, continuously stir to obtain a transparent sol; Mix the glass microspheres with the transparent sol and ultrasonically disperse them, then evaporate and remove the solvent under stirring conditions, and then calcine the product under nitrogen protection conditions to obtain glass microspheres coated with titanium dioxide; (2) Vaporize perfluorooctyltriethoxysilane and deposit it on the surface of the glass microspheres coated with titanium dioxide, and then anneal under nitrogen conditions at 110-130 °C to obtain modified glass microspheres.

[0011] Further, in step (1), the molar ratio of tetrabutyl titanate, ethanol, acetylacetone and water is 1:18-22:0.4-0.6:0.2-0.4; the solid-liquid ratio of the glass microspheres to the transparent sol is 1:1.5-2.5; the calcination temperature is 280-320 °C, and the calcination time is 1.5-3 h.

[0012] Further, in step (2), the volume-mass ratio of perfluorooctyltriethoxysilane to the glass microspheres coated with titanium dioxide is 5 ml:90-110 g; the vaporization temperature of perfluorooctyltriethoxysilane is 140-160 °C.

[0013] The preparation method of the above-mentioned bio-based powder coating with insulation, heat insulation and anti-fingerprint properties includes the following steps: (1) Mix a partially modified bio-based epoxy resin and dicyandiamide in a mass ratio of 100:5 to obtain Mixture 1; (2) Mix the remaining modified bio-based epoxy resin and a partial hydroxy polyester resin in a mass ratio of 1:1 to obtain Mixture 2; (3) Mix the remaining hydroxy polyester resin and isocyanate in a mass ratio of 4:1 to obtain Mixture 3; (4) Mix acrylic acid, modified glass microspheres, glass fiber, talcum powder, thermal expander, pigment, leveling agent, and benzoin to obtain Mixture 4; (5) Mix Mixture 1, Mixture 2, Mixture 3, and Mixture 4 to obtain a total mixture; (6) Perform heating extrusion, cooling, tablet pressing, crushing, grinding, and sieving operations on the total mixture in sequence to obtain a powder coating.

[0014] Further, the heating extrusion temperature in step (6) has three stages. The heating temperature in the first stage is 85 - 95 °C, the heating temperature in the second stage is 96 - 105 °C, and the heating temperature in the third stage is 96 - 105 °C.

[0015] The beneficial effects produced by the present invention are as follows: 1. During the modification process of the bio-based epoxy resin in the present invention, the silane coupling agent can undergo a condensation reaction with the epoxy resin to form a Si - O - C covalent bond, and a bio-based epoxy resin with siloxane groups on the surface is prepared. The grafted siloxane groups can reduce the surface energy of the resin, enhance the binding ability between the resin and the inorganic filler interface, improve the insulation and hydrophobicity of the powder coating, and thus improve the insulation and anti-fingerprint performance of the coating.

[0016] 2. During the surface modification process of the glass microspheres in the present invention, anatase can be attached to the surface of the glass microspheres to improve the infrared reflection performance of the glass microspheres, ultimately reducing the absorption of heat and improving the heat insulation performance of the coating; continue to deposit perfluorooctyltriethoxysilane on the surface of the glass microspheres to form a silane film layer on the surface of the glass microspheres, making the surface of the glass microspheres form a hydrophobic film and improving the hydrophobicity of the glass microspheres. The modified glass microspheres can not only improve the heat insulation performance of the coating but also improve the anti-fingerprint effect of the coating.

[0017] 3. In the present invention, epoxy resin is premixed with dicyandiamide curing agent and isocyanate curing agent respectively, and hydroxyl polyester resin is premixed with isocyanate, so that after the above materials are cured, a uniform and dense three-dimensional cross-linked network structure is formed inside the coating, improving the density of the coating, effectively blocking the migration path of charges, inhibiting the hopping conduction of electrons, and thus realizing the improvement of insulation performance. At the same time, the dense network structure can also improve heat insulation and anti-fingerprint performance. Moreover, in this application, by increasing the dosage of epoxy resin, the encapsulation effect on fillers such as glass beads, glass fibers, and talcum powder is improved, thereby increasing the service life of the coating.

[0018] 4. In the preparation method of the present invention, the resin raw materials and different curing agents are premixed respectively, which can avoid the premature curing of the resin, improve the stability of the powder coating, and thus improve the use effect of the powder coating. Specifically, premixing the modified bio-based epoxy resin with dicyandiamide can avoid dicyandiamide contacting acidic or hydroxyl components, ensuring that the curing reaction occurs in a high-temperature environment after painting; premixing isocyanate with hydroxyl polyester resin can limit the reaction of isocyanate groups with other groups such as carboxyl groups, reducing the occurrence of side reactions; premixing the remaining raw materials such as modified glass beads and glass fibers with acrylic acid can achieve the coating of liquid raw materials on the surface of solid raw materials, improving the uniformity of dispersion in the subsequent coating, reducing the generation of air gaps after the coating is cured, and further improving the anti-fingerprint performance of the coating.

[0019] 5. In the present invention, through staged heating and extrusion, through preliminary cross-linking, the rapid shrinkage of materials to generate cracks is avoided, the generation of defects is reduced, and through the final heating-up, complete cross-linking is achieved to form a defect-free dense structure. The dense structure can not only reduce the risk of electric leakage, but also improve heat insulation performance and anti-fingerprint performance. Description of the Drawings

[0020] Figure 1 It is a physical display diagram of the anti-fingerprint effect of the sample in Example 1. a is the physical diagram of the sample after the first fingerprint pressing, b is the physical diagram of the sample 2 seconds after the first fingerprint pressing, c is the physical diagram of the sample after the second fingerprint pressing, d is the physical diagram of the sample after the third fingerprint pressing, and e is the physical diagram of the sample 6 seconds after the third fingerprint pressing; Figure 2 It is a physical display diagram of the anti-fingerprint effect of the sample in Comparative Example 1. a is the physical diagram of the sample after the first fingerprint pressing, b is the physical diagram of the sample after the second fingerprint pressing, and c is the physical diagram of the sample after the third fingerprint pressing; Figure 3 It is a physical display diagram of the anti-fingerprint effect of the sample in Comparative Example 2. a is the physical diagram of the sample after the first fingerprint pressing, b is the physical diagram of the sample after the second fingerprint pressing, and c is the physical diagram of the sample after the third fingerprint pressing; Figure 4It is a physical display diagram of the anti-fingerprint effect of the sample in Comparative Example 3. a is the physical diagram of the sample after the first fingerprint pressing, b is the physical diagram of the sample after the second fingerprint pressing, and c is the physical diagram of the sample after the third fingerprint pressing. Detailed implementation manners

[0021] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0022] Therefore, the following detailed description of the provided embodiments of the present invention is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of protection of the present invention.

[0023] It should be noted that relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article or device including the element.

[0024] The features and performance of the present invention will be further described in detail below in conjunction with embodiments.

[0025] Embodiment 1 A bio-based powder coating with insulation, heat insulation and anti-fingerprint properties, comprising the following components in parts by weight: 476 parts of modified cashew phenol-based epoxy resin, 22 parts of dicyandiamide, 60 parts of hydroxyl polyester resin, 6 parts of triphenylmethane triisocyanate, 0.5 part of acrylic acid, 50 parts of modified glass microspheres, 5 parts of glass fiber, 10 parts of talcum powder, 0.5 part of thermal expander, 30 parts of pigment, 3 parts of leveling agent, 1 part of benzoin.

[0026] Among them, the preparation method of the modified cardanol-based epoxy resin is as follows: Mix ethanol and water, adjust the pH value of the mixed solution to 4, dropwise add silane coupling agent KH560 thereto, and react for 2 h at 15 °C under stirring conditions to obtain a KH560 hydrolysis solution, wherein the mass ratio of KH560, ethanol, and water is 10:80:10; then under the condition of nitrogen protection, heat the cardanol-based epoxy resin to 80 °C, and dropwise add the KH560 hydrolysis solution thereto under stirring conditions, the mass ratio of the cardanol-based epoxy resin to the KH560 hydrolysis solution is 100:1.5, stir and react for 2 h, and after the reaction is completed, rotate and evaporate to remove the solvent at 60 °C to obtain the modified cardanol-based epoxy resin; The preparation method of the modified glass microspheres is as follows: (1) Under the condition of an ice-water bath, mix ethanol and acetylacetone, dropwise add tetrabutyl titanate thereto, and then dropwise add an aqueous solution containing ammonia water, adjust the pH of the mixed solution to 4, and continuously stir to obtain a transparent sol, wherein the molar ratio of tetrabutyl titanate, ethanol, acetylacetone, and water is 1:20:0.5:0.3; mix the glass microspheres and the transparent sol according to a solid-liquid ratio of 1:2 and ultrasonically disperse them, then evaporate and remove the solvent under stirring conditions, and then calcine the product at 300 °C for 2 h under the condition of nitrogen protection to obtain glass microspheres coated with titanium dioxide; (2) Vaporize perfluorooctyltriethoxysilane at 150 °C and deposit it on the surface of the glass microspheres coated with titanium dioxide, the volume-mass ratio of perfluorooctyltriethoxysilane to the glass microspheres coated with titanium dioxide is 5 ml:100 g, and then anneal at 120 °C under nitrogen to obtain the modified glass microspheres.

[0027] The preparation method of the above bio-based powder coating with insulation, heat insulation, and anti-fingerprint properties includes the following steps: (1) Mix a part of the modified cardanol-based epoxy resin and dicyandiamide according to a mass ratio of 100:5 to obtain mixture 1; (2) Mix the remaining modified cardanol-based epoxy resin and a part of the hydroxyl polyester resin according to a mass ratio of 1:1 to obtain mixture 2; (3) Mix the remaining hydroxyl polyester resin and triphenylmethane triisocyanate according to a mass ratio of 4:1 to obtain mixture 3; (4) Mix acrylic acid, modified glass microspheres, glass fiber, talcum powder, thermal expander, pigment, leveling agent, and benzoin to obtain mixture 4; (5) Mix mixture 1, mixture 2, mixture 3, and mixture 4 to obtain a total mixture; (6) Heat and extrude the premix. The feeding speed of the extruder is 30 rpm, the main machine speed is 50 rpm, and the extrusion temperature is divided into three stages. The heating temperature in the first stage is 90 °C, the heating temperature in the second stage is 100 °C, and the heating temperature in the third stage is 100 °C; then it undergoes cooling and tablet pressing, crushing, grinding, and sieving operations in sequence to obtain a powder coating with a particle size D50 = 40 μm ± 5 μm. Among them, the tablet pressing speed is 20 rpm, the feeding speed during grinding is 25 rpm, the main grinding speed is 50 rpm, the auxiliary grinding speed is 25 rpm, and the mesh number of the sieve is 200 mesh.

[0028] Example 2 A bio-based powder coating with insulation, heat insulation, and anti-fingerprint properties, comprising the following components in parts by weight: 593 parts of modified itaconic acid-based epoxy resin, 28 parts of dicyandiamide, 65 parts of hydroxyl polyester resin, 8 parts of triphenylmethane triisocyanate, 0.3 part of acrylic acid, 40 parts of modified glass beads, 3 parts of glass fiber, 15 parts of talcum powder, 0.3 part of thermal expander, 20 parts of pigment, 4 parts of leveling agent, 0.5 part of benzoin.

[0029] Among them, the preparation method of the modified itaconic acid-based epoxy resin is as follows: Mix ethanol and water, adjust the pH value of the mixed solution to 4, dropwise add KH560 thereto, and react at 20 °C under stirring conditions for 1.5 h to obtain a KH560 hydrolysis solution. Among them, the mass ratio of KH560, ethanol, and water is 8:80:12; then under nitrogen protection conditions, heat the itaconic acid-based epoxy resin to 85 °C, and dropwise add the KH560 hydrolysis solution thereto under stirring conditions. The mass ratio of the itaconic acid-based epoxy resin to the KH560 hydrolysis solution is 100:1, stir and react for 2 h, and after the reaction, rotate and evaporate to remove the solvent at 60 °C to obtain the modified itaconic acid-based epoxy resin; The preparation method of the modified glass beads is as follows: (1) Under ice-water bath conditions, mix ethanol and acetylacetone, dropwise add tetrabutyl titanate thereto, and then dropwise add an aqueous solution containing ammonia water, adjust the pH of the mixed solution to 3, and continuously stir to obtain a transparent sol. Among them, the molar ratio of tetrabutyl titanate, ethanol, acetylacetone, and water is 1:18:0.6:0.2; Mix the glass beads and the transparent sol according to a solid-liquid ratio of 1:1.5 and ultrasonically disperse them, then evaporate and remove the solvent under stirring conditions, and then calcine the product at 280 °C for 3 h under nitrogen protection conditions to obtain glass beads coated with titanium dioxide; (2) Vaporize perfluorooctyltriethoxysilane at 140 °C and deposit it on the surface of the glass beads coated with titanium dioxide. The volume-mass ratio of perfluorooctyltriethoxysilane to the glass beads coated with titanium dioxide is 5 ml:90 g, and then anneal under nitrogen conditions at 110 °C to obtain the modified glass beads.

[0030] The preparation method of the above-mentioned bio-based powder coating with insulation, heat insulation and fingerprint resistance properties comprises the following steps: (1) Mix part of the modified itaconic acid-based epoxy resin and dicyandiamide according to a mass ratio of 100:5 to obtain mixture 1; (2) Mix the remaining modified itaconic acid-based epoxy resin and part of the hydroxyl polyester resin according to a mass ratio of 1:1 to obtain mixture 2; (3) Mix the remaining hydroxyl polyester resin and triphenylmethane triisocyanate according to a mass ratio of 4:1 to obtain mixture 3; (4) Mix acrylic acid, modified glass microspheres, glass fiber, talcum powder, thermal expander, pigment, leveling agent and benzoin to obtain mixture 4; (5) Mix mixture 1, mixture 2, mixture 3 and mixture 4 to obtain the total mixture; (6) Heat and extrude the total mixture. The feeding speed of the extruder is 30 rpm, the main machine speed is 50 rpm, and the extrusion temperature is divided into three stages. The heating temperature in the first stage is 85 °C, the heating temperature in the second stage is 96 °C, and the heating temperature in the third stage is 96 °C; then successively pass through cooling and tablet pressing, crushing, grinding and sieving operations to obtain a powder coating with a particle size D50 = 40 μm ± 5 μm, wherein the tablet pressing speed is 20 rpm, the feeding speed during grinding is 25 rpm, the main grinding speed is 50 rpm, the secondary grinding speed is 25 rpm, and the mesh number of the sieve is 200 mesh.

[0031] Example 3 A bio-based powder coating with insulation, heat insulation and fingerprint resistance properties, comprising the following components in parts by weight: 439 parts of modified cardanol-based epoxy resin, 20 parts of dicyandiamide, 55 parts of hydroxyl polyester resin, 4 parts of triphenylmethane triisocyanate, 0.8 part of acrylic acid, 60 parts of modified glass microspheres, 8 parts of glass fiber, 7 parts of talcum powder, 0.8 part of thermal expander, 40 parts of pigment, 2 parts of leveling agent, 1.5 parts of benzoin.

[0032] Among them, the preparation method of the modified cardanol-based epoxy resin is as follows: Mix ethanol and water, adjust the pH value of the mixed solution to 5, dropwise add silane coupling agent KH560 thereto, and react at 15 °C under stirring conditions for 3 h to obtain KH560 hydrolysis solution, wherein the mass ratio of KH560, ethanol and water is 12:80:8; the mass ratio of cardanol-based epoxy resin to KH560 is 100:2; then under nitrogen protection conditions, heat the cardanol-based epoxy resin to 75 °C, and dropwise add KH560 hydrolysis solution thereto under stirring conditions, the mass ratio of cardanol-based epoxy resin to KH560 hydrolysis solution is 100:2, stir and react for 2 h, and after the reaction, rotate and evaporate to remove the solvent at 60 °C to obtain the modified cardanol-based epoxy resin; The preparation method of the modified glass microspheres is as follows: (1) Under the condition of an ice-water bath, ethanol and acetylacetone are mixed, tetrabutyl titanate is added dropwise thereto, and then an aqueous solution containing ammonia is added dropwise thereto, and the pH of the mixed solution is adjusted to 4, and continuous stirring is carried out to obtain a transparent sol. Among them, the molar ratio of tetrabutyl titanate, ethanol, acetylacetone and water is 1:22:0.4:0.4; the glass microspheres and the transparent sol are mixed according to a solid-liquid ratio of 1:2.5 and ultrasonically dispersed, and then the solvent is removed by evaporation under stirring conditions, and then the product is calcined at 320 °C for 1.5 h under nitrogen protection to obtain glass microspheres coated with titanium dioxide; (2) Perfluorooctyltriethoxysilane is vaporized and deposited on the surface of the glass microspheres coated with titanium dioxide at 150 °C. The volume-mass ratio of perfluorooctyltriethoxysilane to the glass microspheres coated with titanium dioxide is 5 ml:110 g, and then annealing is carried out under nitrogen conditions at 130 °C to obtain the modified glass microspheres.

[0033] The preparation method of the above-mentioned bio-based powder coating with insulation, heat insulation and anti-fingerprint properties includes the following steps: (1) Part of the modified cardanol-based epoxy resin and dicyandiamide are mixed evenly according to a mass ratio of 100:5 to obtain mixture 1; (2) The remaining modified cardanol-based epoxy resin and part of the hydroxyl polyester resin are mixed evenly according to a mass ratio of 1:1 to obtain mixture 2; (3) The remaining hydroxyl polyester resin and triphenylmethane triisocyanate are mixed evenly according to a mass ratio of 4:1 to obtain mixture 3; (4) Acrylic acid, modified glass microspheres, glass fiber, talcum powder, thermal expander, pigment, leveling agent and benzoin are mixed evenly to obtain mixture 4; (5) Mixture 1, mixture 2, mixture 3 and mixture 4 are mixed evenly to obtain the total mixture; (6) The total mixture is heated and extruded. The feeding speed of the extruder is 30 rpm, the main machine speed is 50 rpm, and the extrusion temperature is divided into three stages. The heating temperature in the first stage is 95 °C, the heating temperature in the second stage is 105 °C, and the heating temperature in the third stage is 105 °C; then it is successively subjected to cooling and pressing, crushing, grinding and sieving operations to obtain a powder coating with a particle size D50 = 40 μm ± 5 μm. Among them, the pressing speed is 20 rpm, the feeding speed during grinding is 25 rpm, the main grinding speed is 50 rpm, the secondary grinding speed is 25 rpm, and the mesh number of the sieve is 200 mesh.

[0034] Example 4 A bio-based powder coating with insulation, heat insulation, and fingerprint resistance properties, comprising the following components in parts by weight: 512 parts of modified cardanol-based epoxy resin, 24 parts of dicyandiamide, 60 parts of hydroxyl polyester resin, 7 parts of triphenylmethane triisocyanate, 0.6 parts of acrylic acid, 45 parts of modified glass microspheres, 7 parts of glass fiber, 12 parts of talcum powder, 0.6 parts of thermal expander, 35 parts of pigment, 3 parts of leveling agent, and 1 part of benzoin.

[0035] Among them, the preparation method of the modified cardanol-based epoxy resin is as follows: Mix ethanol and water, adjust the pH value of the mixed solution to 5, dropwise add silane coupling agent KH560 thereto, and react at 20 °C under stirring conditions for 2 h to obtain KH560 hydrolysis solution, wherein the mass ratio of KH560, ethanol, and water is 8:80:12; the mass ratio of cardanol-based epoxy resin to KH560 is 100:1.5; then under nitrogen protection conditions, heat the cardanol-based epoxy resin to 85 °C, and dropwise add KH560 hydrolysis solution thereto under stirring conditions, the mass ratio of cardanol-based epoxy resin to KH560 hydrolysis solution is 100:1, stir and react for 2 h, and after the reaction, rotate and evaporate to remove the solvent at 60 °C to obtain the modified cardanol-based epoxy resin; The preparation method of the modified glass microspheres is as follows: (1) Under ice-water bath conditions, mix ethanol and acetylacetone, dropwise add tetrabutyl titanate thereto, and then dropwise add an aqueous solution containing ammonia water, adjust the pH of the mixed solution to 4, and continuously stir to obtain a transparent sol, wherein the molar ratio of tetrabutyl titanate, ethanol, acetylacetone, and water is 1:18:0.6:0.4; mix the glass microspheres and the transparent sol according to a solid-liquid ratio of 1:2 and ultrasonically disperse, then evaporate to remove the solvent under stirring conditions, and then calcine the product at 320 °C under nitrogen protection for 3 h to obtain glass microspheres coated with titanium dioxide; (2) Vaporize perfluorooctyltriethoxysilane at 155 °C and deposit it on the surface of the glass microspheres coated with titanium dioxide, the volume-mass ratio of perfluorooctyltriethoxysilane to the glass microspheres coated with titanium dioxide is 5 ml:105 g, and then anneal under nitrogen conditions at 125 °C to obtain the modified glass microspheres.

[0036] The preparation method of the above bio-based powder coating with insulation, heat insulation, and fingerprint resistance properties includes the following steps: (1) Mix part of the modified cardanol-based epoxy resin and dicyandiamide according to a mass ratio of 100:5 to obtain mixture 1; (2) Mix the remaining modified cardanol-based epoxy resin and part of the hydroxyl polyester resin according to a mass ratio of 1:1 to obtain mixture 2; (3) Mix the remaining hydroxyl polyester resin and triphenylmethane triisocyanate according to a mass ratio of 4:1 to obtain mixture 3; (4) Mix acrylic acid, modified glass microspheres, glass fiber, talcum powder, thermal expander, pigment, leveling agent and benzoin evenly to obtain mixture 4; (5) Mix mixture 1, mixture 2, mixture 3 and mixture 4 evenly to obtain the total mixture; (6) Heat and extrude the total mixture. The feeding speed of the extruder is 30 rpm, the main machine speed is 50 rpm, and the extrusion temperature is divided into three stages. The heating temperature in the first stage is 90 °C, the heating temperature in the second stage is 102 °C, and the heating temperature in the third stage is 102 °C; then successively pass through cooling and tablet pressing, crushing, grinding and sieving operations to obtain a powder coating with a particle size D50 = 40 μm ± 5 μm. Among them, the tablet pressing speed is 20 rpm, the feeding speed during grinding is 25 rpm, the main grinding speed is 50 rpm, the secondary grinding speed is 25 rpm, and the mesh number of the sieve is 200 mesh.

[0037] Comparative Example 1 A bio-based powder coating, comprising the following components in parts by weight: 476 parts of cardanol-based epoxy resin, 22 parts of dicyandiamide, 60 parts of hydroxyl polyester resin, 6 parts of triphenylmethane triisocyanate, 0.5 part of acrylic acid, 50 parts of glass microspheres, 5 parts of glass fiber, 10 parts of talcum powder, 0.5 part of thermal expander, 30 parts of pigment, 3 parts of leveling agent, 1 part of benzoin.

[0038] The preparation method of the above bio-based powder coating comprises the following steps: (1) Mix a part of cardanol-based epoxy resin and dicyandiamide in a mass ratio of 100:5 evenly to obtain mixture 1; (2) Mix the remaining cardanol-based epoxy resin and a part of hydroxyl polyester resin in a mass ratio of 1:1 evenly to obtain mixture 2; (3) Mix the remaining hydroxyl polyester resin and triphenylmethane triisocyanate in a mass ratio of 4:1 evenly to obtain mixture 3; (4) Mix acrylic acid, glass microspheres, glass fiber, talcum powder, thermal expander, pigment, leveling agent and benzoin evenly to obtain mixture 4; (5) Mix mixture 1, mixture 2, mixture 3 and mixture 4 evenly to obtain the total mixture; (6) Heat and extrude the total mixture. The feeding speed of the extruder is 30 rpm, the main machine speed is 50 rpm, and the extrusion temperature is divided into three stages. The heating temperature in the first stage is 90 °C, the heating temperature in the second stage is 100 °C, and the heating temperature in the third stage is 100 °C; then successively pass through cooling and tablet pressing, crushing, grinding and sieving operations to obtain a powder coating with a particle size D50 = 40 μm ± 5 μm. Among them, the tablet pressing speed is 20 rpm, the feeding speed during grinding is 25 rpm, the main grinding speed is 50 rpm, the secondary grinding speed is 25 rpm, and the mesh number of the sieve is 200 mesh.

[0039] Comparative Example 2 A bio-based powder coating, comprising the following components in parts by weight: 476 parts of modified cardanol-based epoxy resin, 22 parts of dicyandiamide, 60 parts of hydroxyl polyester resin, 6 parts of triphenylmethane triisocyanate, 0.5 part of acrylic acid, 50 parts of modified glass beads, 5 parts of glass fiber, 10 parts of talcum powder, 0.5 part of thermal expander, 30 parts of pigment, 3 parts of leveling agent, and 1 part of benzoin.

[0040] Among them, the preparation method of the modified cardanol-based epoxy resin is as follows: Mix ethanol and water, adjust the pH value of the mixed solution to 4, dropwise add silane coupling agent KH560 thereto, and react at 15 °C under stirring conditions for 2 h to obtain KH560 hydrolysis solution, wherein the mass ratio of KH560, ethanol and water is 10:80:10; then under nitrogen protection, heat the cardanol-based epoxy resin to 80 °C, and dropwise add the KH560 hydrolysis solution thereto under stirring conditions, and the mass ratio of the cardanol-based epoxy resin to the KH560 hydrolysis solution is 100:1.5, stir and react for 2 h, and after the reaction is completed, rotate and evaporate to remove the solvent at 60 °C to obtain the modified cardanol-based epoxy resin; The preparation method of the modified glass beads is as follows: (1) Under ice-water bath conditions, mix ethanol and acetylacetone, dropwise add tetrabutyl titanate thereto, and then dropwise add deionized water to obtain a mixed solution, adjust the pH of the mixed solution to 4, and continuously stir to obtain a transparent sol, wherein the molar ratio of tetrabutyl titanate, ethanol, acetylacetone and water is 1:20:0.5:0.3; mix the glass beads and the transparent sol according to a solid-liquid ratio of 1:2 and ultrasonically disperse, then evaporate and remove the solvent under stirring conditions, and then calcine the product at 300 °C for 2 h under nitrogen protection to obtain glass beads coated with titanium dioxide; (2) Vaporize perfluorooctyltriethoxysilane at 150 °C and deposit it on the surface of the glass beads coated with titanium dioxide. The volume-mass ratio of perfluorooctyltriethoxysilane to the glass beads coated with titanium dioxide is 5 ml:100 g, and then anneal at 120 °C under nitrogen to obtain the modified glass beads.

[0041] The preparation method of the above bio-based powder coating comprises the following steps: (1) Pour all the raw materials into a mixer and mix for 3 h to obtain a total mixture; (2) Heat and extrude the premix. The feeding speed of the extruder is 30 rpm, the main machine speed is 50 rpm, and the extrusion temperature is divided into three stages. The heating temperature in the first stage is 90 °C, the heating temperature in the second stage is 100 °C, and the heating temperature in the third stage is 100 °C; then successively pass through cooling and tablet pressing, crushing, grinding, and sieving operations to obtain a powder coating with a particle size D50 = 40 μm ± 5 μm. Among them, the tablet pressing speed is 20 rpm, the feeding speed during grinding is 25 rpm, the main grinding speed is 50 rpm, the secondary grinding speed is 25 rpm, and the mesh number of the sieve is 200 mesh.

[0042] Comparative Example 3 A bio-based powder coating, comprising the following components in parts by weight: 476 parts of modified cardanol-based epoxy resin, 22 parts of dicyandiamide, 60 parts of hydroxyl polyester resin, 6 parts of triphenylmethane triisocyanate, 0.5 part of acrylic acid, 50 parts of modified glass beads, 5 parts of glass fiber, 10 parts of talcum powder, 0.5 part of thermal expander, 30 parts of pigment, 3 parts of leveling agent, and 1 part of benzoin.

[0043] Among them, the preparation method of the modified cardanol-based epoxy resin is as follows: Mix ethanol and water, adjust the pH value of the mixed solution to 4, dropwise add silane coupling agent KH560 to it, and react at 15 °C under stirring conditions for 2 h to obtain KH560 hydrolysis solution. Among them, the mass ratio of KH560, ethanol, and water is 10:80:10; then under the condition of nitrogen protection, heat the cardanol-based epoxy resin to 80 °C, and dropwise add the KH560 hydrolysis solution to it under stirring conditions. The mass ratio of the cardanol-based epoxy resin to the KH560 hydrolysis solution is 100:1.5, stir and react for 2 h, and after the reaction, rotate and evaporate to remove the solvent at 60 °C to obtain the modified cardanol-based epoxy resin; The preparation method of the modified glass beads is as follows: (1) Under the condition of an ice-water bath, mix ethanol and acetylacetone, dropwise add tetrabutyl titanate to it, and then dropwise add deionized water to obtain a mixed solution. Adjust the pH of the mixed solution to 4, continuously stir to obtain a transparent sol. Among them, the molar ratio of tetrabutyl titanate, ethanol, acetylacetone, and water is 1:20:0.5:0.3; Mix the glass beads and the transparent sol according to a solid-liquid ratio of 1:2 and ultrasonically disperse them, then evaporate and remove the solvent under stirring conditions, and then calcine the product at 300 °C for 2 h under nitrogen protection to obtain glass beads coated with titanium dioxide; (2) Vaporize perfluorooctyltriethoxysilane at 150 °C and deposit it on the surface of the glass beads coated with titanium dioxide. The volume-mass ratio of perfluorooctyltriethoxysilane to the glass beads coated with titanium dioxide is 5 ml:100 g, and then anneal at 120 °C under nitrogen to obtain the modified glass beads.

[0044] The preparation method of the above bio-based powder coating includes the following steps: (1) Mix a partial modified cashew phenol-based epoxy resin and dicyandiamide in a mass ratio of 100:5 to obtain Mixture 1; (2) Mix the remaining modified cashew phenol-based epoxy resin and a partial hydroxyl polyester resin in a mass ratio of 1:1 to obtain Mixture 2; (3) Mix the remaining hydroxyl polyester resin and triphenylmethane triisocyanate in a mass ratio of 4:1 to obtain Mixture 3; (4) Mix acrylic acid, modified glass microspheres, glass fiber, talcum powder, thermal expander, pigment, leveling agent and benzoin to obtain Mixture 4; (5) Mix Mixture 1, Mixture 2, Mixture 3 and Mixture 4 to obtain the total mixture; (6) Heat and extrude the total mixture. The feeding speed of the extruder is 30 rpm, the main machine speed is 50 rpm, and the extrusion temperature is 120 °C; then successively carry out cooling and pressing, crushing, grinding, and sieving operations to obtain a powder coating with a particle size D50 = 40 μm ± 5 μm. Among them, the pressing speed is 20 rpm, the feeding speed during grinding is 25 rpm, the main grinding speed is 50 rpm, the secondary grinding speed is 25 rpm, and the mesh number of the sieve is 200 mesh.

[0045] The hydroxyl polyester resin, thermal expander, pigment, and leveling agent used in the above examples and comparative examples are the same, and they are all commercially available products.

[0046] Test Example Taking the powder coatings prepared in Example 1 and Comparative Examples 1-3 as examples, the coatings were respectively applied to the aluminum plate by electrostatic coating (keeping the spraying parameters consistent), and then heated and cured to obtain specimens. Then, the insulation, heat insulation, and fingerprint resistance properties of the coatings were measured. The specific results are shown in Table 1.

[0047] Insulation voltage withstand test: Apply a gradually increasing alternating voltage to the surface of the specimen, and observe and record the voltage when the coating breaks down; Heat insulation performance test: Use an infrared heating lamp to irradiate and heat one side of the coating of the specimen, measure the temperatures on the heated side and the back side of the coating, and calculate the temperature difference between the two sides, denoted as △T1; as a control, use an infrared heating lamp to irradiate and heat one side of the aluminum plate without coating, and keep the heating temperature and time the same as above, calculate the temperature difference between the two sides of the aluminum plate, denoted as △T2, and the percentage (%) of the temperature difference between the two sides of the coating ; Fingerprint resistance performance: Dip a finger in fingerprint oil (composed of 70% glycerin, 25% water, and 5% urea), and evenly apply a circular area with a diameter of about 20 mm on the surface of the coating, and let it stand for 10 min to simulate the fingerprint drying process, and observe the obviousness of the fingerprint marks in the applied area and the unapplied area; Table 1: Test Results From the data in the above table, it can be known that the powder coatings produced by the method in Example 1 have good insulation performance, heat insulation performance and anti-fingerprint performance. Compared with Example 1, in Comparative Example 1, the modification treatment of bio-based epoxy resin and glass microspheres was cancelled; in Comparative Example 2, the premixing treatment was cancelled; in Comparative Example 3, the staged heating treatment during the heating process was cancelled. From the final results, it can be seen that after adjusting the formulation and preparation method, the performance of the prepared coatings decreased, further proving that the above operations are crucial for the performance of the coatings.

[0048] Figure 1 It is a physical display diagram of the anti-fingerprint effect of the sample in Example 1. Among them, Figures a, b, c, d, and e were taken in chronological order. The results show that after the first fingerprint pressing, fingerprint marks can be seen at the edge position of the fingerprint on the surface of the sample (Figure a), but after 2 seconds, the fingerprint marks almost disappear, and only a little remains at the lower edge position (Figure b). When the fingerprint is pressed for the second time, the fingerprint marks of the first pressing have completely disappeared at this time (Figure c). When the fingerprint is pressed for the third time, the fingerprint marks of the second pressing have also completely disappeared at this time (Figure d). The results show that all fingerprint marks have disappeared 6 seconds after the third fingerprint pressing (Figure e). It can be seen that the sample in this application has good anti-fingerprint effect.

[0049] Figure 2 It is a physical display diagram of the anti-fingerprint effect of the sample in Comparative Example 1. Among them, Figures a, b, and c were taken in chronological order. The results show that after the first fingerprint pressing, obvious fingerprint marks remain on the surface of the sample (Figure a). After 9 seconds, when the fingerprint is pressed for the second time, the fingerprint of the first pressing is still obvious and shows no tendency to disappear (Figure b). After 5 seconds, when the fingerprint is pressed for the third time, the fingerprints of the first and second pressings still exist and show no tendency to disappear (Figure c), proving that the anti-fingerprint effect of the sample in Comparative Example 1 is not obvious and there are fingerprint residues after pressing.

[0050] Figure 3 It is a physical display diagram of the anti-fingerprint effect of the sample in Comparative Example 2. The results show that Figures a, b, and c were taken in chronological order. The results show that after the first fingerprint pressing, obvious fingerprint marks remain on the surface of the sample (Figure a). After 4 seconds, when the fingerprint is pressed for the second time, the fingerprint of the first pressing is still obvious and shows no tendency to disappear (Figure b). After 5 seconds, when the fingerprint is pressed for the third time, the fingerprints of the first and second pressings still exist and show no tendency to disappear (Figure c), proving that the anti-fingerprint effect of the sample in Comparative Example 1 is not obvious and there are fingerprint residues after pressing.

[0051] Figure 4It is a physical display diagram of the anti-fingerprint effect of the sample in Comparative Example 3. The results show that Figures a, b, and c were taken in chronological order. The results show that after the first fingerprint pressing, obvious fingerprint marks remained on the surface of the sample (Figure a). After 4 seconds, the second fingerprint was pressed, and at this time, the fingerprint pressed for the first time was still obvious and showed no tendency to disappear (Figure b). After 4 seconds, the third fingerprint was pressed, and at this time, the fingerprints pressed for the first time and the second time still existed and showed no tendency to disappear (Figure c), proving that the anti-fingerprint effect of the sample in Comparative Example 1 was not obvious and fingerprints remained after pressing.

Claims

1. A bio-based powder coating with insulation, heat insulation and fingerprint resistance properties, characterized in that, It comprises the following components in parts by weight: 439 - 593 parts of modified bio - based epoxy resin, 20 - 28 parts of dicyandiamide, 55 - 65 parts of hydroxyl polyester resin, 4 - 8 parts of isocyanate, 0.3 - 0.8 parts of acrylic acid, 40 - 60 parts of modified glass microspheres, 3 - 8 parts of glass fiber, 7 - 15 parts of talcum powder, 0.3 - 0.8 parts of thermal expander, 20 - 40 parts of pigment, 2 - 4 parts of leveling agent, 0.5 - 1.5 parts of benzoin.

2. The bio-based powder coating with insulation, heat insulation and fingerprint resistance properties as claimed in claim 1, wherein The preparation method of the modified bio - based epoxy resin is as follows: Mix ethanol and water, adjust the pH value of the mixed solution to 4 - 5, dropwise add a silane coupling agent thereto, react at 4 - 30 °C under stirring conditions for 1.5 - 3 h to obtain a silane coupling agent hydrolysis solution; Under the condition of nitrogen protection, heat the bio - based epoxy resin to 75 - 85 °C, then dropwise add the silane coupling agent hydrolysis solution thereto under stirring conditions, stir and react, and after the reaction is completed, remove the solvent by rotary evaporation to obtain the modified bio - based epoxy resin.

3. The bio-based powder coating with insulation, heat insulation and fingerprint resistance properties as described in claim 2, wherein The mass ratio of the silane coupling agent, ethanol and water is 8 - 12:75 - 85:8 - 12; The mass ratio of the bio - based epoxy resin to the silane coupling agent is 100:1 - 2.

4. The bio-based powder coating having insulation, heat insulation and fingerprint resistance properties according to any one of claims 1-3, characterized in that, The bio - based epoxy resin includes itaconic acid - based epoxy resin and cardanol - based epoxy resin, and the silane coupling agent is KH560.

5. The bio-based powder coating having insulation, heat insulation and fingerprint resistance properties as claimed in claim 1, wherein The isocyanate is triphenylmethane triisocyanate.

6. The bio-based powder coating having insulation, heat insulation and fingerprint resistance properties as claimed in claim 1, wherein, The preparation method of the modified glass microspheres is as follows: (1) Under the condition of an ice - water bath, mix ethanol and acetylacetone, and dropwise add tetrabutyl titanate thereto to obtain a mixed solution, then dropwise add an aqueous solution containing ammonia to adjust the pH of the mixed solution to 3 - 4, continuously stir to obtain a transparent sol; Mix the glass microspheres with the transparent sol and ultrasonically disperse them, then evaporate the solvent under stirring conditions, and then calcine the product under the condition of nitrogen protection to obtain glass microspheres coated with titanium dioxide; (2) Vaporize perfluorooctyltriethoxysilane and deposit it on the surface of the glass microspheres coated with titanium dioxide, and then anneal under nitrogen conditions at 110 - 130 °C to obtain modified glass microspheres.

7. The bio-based powder coating with insulation, heat insulation and fingerprint resistance properties according to claim 6, characterized in that, In step (1), the molar ratio of tetrabutyl titanate, ethanol, acetylacetone and water is 1:18 - 22:0.4 - 0.6:0.2 - 0.4; The solid - liquid ratio of the glass microspheres to the transparent sol is 1:1.5 - 2.5; The calcination temperature is 280 - 320 °C, and the calcination time is 1.5 - 3 h.

8. The bio-based powder coating having insulation, heat insulation and fingerprint resistance properties according to claim 6, characterized in that, In step (2), the volume - mass ratio of perfluorooctyltriethoxysilane to the glass microspheres coated with titanium dioxide is 5 ml:90 - 110 g; The vaporization temperature of perfluorooctyltriethoxysilane is 140 - 160 °C.

9. The preparation method of the bio - based powder coating having insulation, heat - insulation and fingerprint - resistant properties according to any one of claims 1 - 8, characterized in that (1) Mix a part of the modified bio - based epoxy resin and dicyandiamide according to a mass ratio of 100:5 to obtain mixture 1; (2) Mix the remaining modified bio - based epoxy resin and a part of the hydroxyl polyester resin according to a mass ratio of 1:1 to obtain mixture 2; (3) Mix the remaining hydroxyl polyester resin and isocyanate according to a mass ratio of 4:1 to obtain mixture 3; (4) Mix acrylic acid, modified glass microspheres, glass fiber, talcum powder, thermal expander, pigment, leveling agent and benzoin to obtain mixture 4; (5) Mix mixture 1, mixture 2, mixture 3 and mixture 4 to obtain the total mixture; (6) Perform heating extrusion, cooling, tablet pressing, crushing, grinding and sieving operations on the total mixture in sequence to obtain the powder coating.

10. The preparation method of the bio-based powder coating with insulation, heat insulation and fingerprint resistance according to claim 9, characterized in that, In step (6), the heating extrusion temperature has three stages. The heating temperature in the first stage is 85 - 95 °C, the heating temperature in the second stage is 96 - 105 °C, and the heating temperature in the third stage is 96 - 105 °C.

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