Preparation method of mesoporous silica hollow sphere insulating paint

Abstract

The invention relates to the technical field of insulating paint, in particular to a preparation method of mesoporous silica hollow sphere insulating paint, which comprises the following steps: synthesizing mesoporous silica hollow spheres as filler by adopting a double-template emulsion method; the preparation method comprises the following steps: carrying out modification treatment on mesoporous silica hollow spheres, preparing boric acid group modified mesoporous silica hollow spheres by using 3-aminophenylboronic acid, and then grafting a bio-based flame retardant containing an ortho-dihydroxyl structure; the bio-based flame retardant containing the o-dihydroxyl structure is prepared by the following steps: preparing vanillin-based diol from a green raw material vanillin and 3-chloro-1, 2-propylene glycol, and then continuously synthesizing the vanillin-based diol, 2-aminobenzothiazole and DOPO into the bio-based flame retardant containing nitrogen, phosphorus and sulfur elements. The self-repairing flame-retardant prepolymer is introduced into the insulating paint, so that the service life of the insulating paint is effectively prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of insulating varnishes, in particular to a method for preparing mesoporous silicon dioxide hollow ball insulating varnish. Background Art

[0002] With the advancement of technology, the application scope of insulating varnishes with heat resistance and electrical insulation is constantly expanding. For example, when applied to motors, the performance of insulating varnishes is closely related to the performance and life of the motors.

[0003] Nowadays, in order to improve the heat resistance of insulating paint, a high content of thermal conductive materials is usually added to improve it. However, there are also the following problems: the added thermal conductive materials are unevenly dispersed in the insulating paint base material, making it difficult to achieve good heat resistance. At the same time, the compatibility of the thermal conductive material with the surface interface of organic matter further limits its effectiveness. In addition, the existing insulating paint has a single function, which greatly limits its scope of use. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing mesoporous silica hollow sphere insulating varnish to solve the problems raised in the prior art.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for preparing mesoporous hollow silica spheres comprises the following steps:

[0007] The catalyst, surfactant and ultrapure water are mixed, and an organic solvent and a silicon source are added in sequence, and the mixture is heat-treated in an oil bath, and the mixture is transferred to a hydrothermal kettle for heat treatment, filtered, dried and calcined to obtain mesoporous silica hollow spheres.

[0008] Furthermore, the catalyst is one or a combination of ammonia water, ethylenediamine, dodecylamine, triethanolamine and diethanolamine.

[0009] Furthermore, the surfactant is a cationic surfactant and a non-ionic surfactant compounded in a mass ratio of (1-3):1; the organic solvent is a compound of one or more of dioxane, cyclohexane, n-hexane, octadecene, and decahydronaphthalene; and the silicon source is a compound of one or more of methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, and butyl orthosilicate.

[0010] Furthermore, the working conditions of the oil bath insulation treatment are: temperature 30-80°C, time 22-24h; the working conditions of the heat treatment are: temperature 60-80°C, time 12-24h; the working conditions of the roasting are: temperature 500-1000°C, time 1-5h.

[0011] Furthermore, the mass ratio of the surfactant to the silicon source is 0.05-0.5.

[0012] Furthermore, a method for preparing a mesoporous hollow silica sphere insulating varnish comprises the following steps:

[0013] S1: Preparation of composite mesoporous silica hollow spheres using mesoporous silica hollow spheres;

[0014] S2: Mix epoxy resin, dispersant and solvent, add composite mesoporous silica hollow spheres and additives, stir and grind, add self-healing prepolymer, add curing agent, and obtain a mesoporous silica hollow sphere insulating paint.

[0015] Furthermore, the raw material composition of the insulating paint is, by weight: 1-5 parts of composite mesoporous silica hollow spheres, 20-35 parts of solvent, 16-26 parts of epoxy resin, 7-13 parts of self-healing flame retardant prepolymer, 1-5 parts of dispersant, 2-5 parts of auxiliary agent, and 8-15 parts of curing agent.

[0016] Furthermore, the auxiliary agent is one or more of a defoamer, a film-forming agent, a leveling agent, an anti-settling agent, and a wetting agent; and the solvent is one or more of a defoamer, anhydrous ethanol, methanol, and N,N-dimethylacetamide.

[0017] Furthermore, the curing agent is an amine curing agent.

[0018] Furthermore, the preparation of composite mesoporous silica hollow spheres includes the following steps:

[0019] The mesoporous silica hollow spheres and deionized water are mixed, 3-aminophenylboric acid is added, ultrasonic dispersion is performed for 1-2 hours, stirring is performed for 10-12 hours in a dark environment, centrifugation is performed, a bio-based flame retardant containing an ortho-dihydroxy structure is added, the pH value is adjusted to 9, stirring is continued for 5-6 hours, washing and drying are performed to obtain composite mesoporous silica hollow spheres.

[0020] Furthermore, the preparation of the self-healing flame-retardant prepolymer includes the following steps: under a nitrogen atmosphere, hydrogenated terminal hydroxyl polybutadiene and isophorone diisocyanate are mixed, kept warm at 78-82°C for 50-70 minutes, dibutyltin dilaurate is added, the heat preservation is continued for 1-2 hours, a mixed solution of 4,4'-diaminodiphenyl disulfide and anhydrous tetrahydrofuran is added, the heat preservation is continued for 1-2 hours, a mixed solution of a bio-based flame retardant containing an ortho-dihydroxy structure and anhydrous tetrahydrofuran is added, the temperature is reduced to 30-35°C, triethylamine is added, rotary evaporation is performed, and the material is discharged to obtain a self-healing flame-retardant prepolymer.

[0021] Furthermore, the preparation of the bio-based flame retardant containing an ortho-dihydroxy structure comprises the following steps:

[0022] 1) Mix sodium hydroxide and deionized water, transfer to a nitrogen environment at 18-25° C., add vanillin, stir at 78-82° C. for 50-70 min, add 3-chloro-1,2-propanediol, heat to 98-100° C. and stir for 3-4 h, extract with n-butanol, wash with water, and rotary evaporate, recrystallize with ethyl acetate and n-hexane in a mass ratio of 1:1, filter, and dry to obtain vanillin-based diol;

[0023] 2) Under a nitrogen atmosphere, vanillin diol, 2-aminobenzothiazole and anhydrous ethanol are mixed, stirred at 60-65° C. for 8-10 hours, a mixed solution of DOPO and anhydrous ethanol is added, and stirring is continued for 10-12 hours. The mixture is filtered, washed and dried to obtain a bio-based flame retardant containing an ortho-dihydroxy structure.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The invention provides a method for preparing a mesoporous silica hollow ball insulating varnish, optimizes its components, and prepares a multifunctional insulating varnish with good electrical insulation, high temperature resistance, high flame retardancy, and self-repairing properties.

[0026] In order to improve the heat resistance of insulating paint, the present invention adopts a double-template emulsion method to synthesize simple-operation, spherical and stable mesoporous silica hollow spheres as fillers. During the preparation process, a non-ionic surfactant with a longer molecular weight is introduced into the surfactant. Filling in the emulsion can provide a higher emulsion ball hardness and give the mesoporous hollow spheres a better spherical morphology. The reaction solution is hydrothermally treated to increase the hardness of the mesoporous layer, effectively maintaining the stability of the spherical morphology of the mesoporous hollow spheres, which is beneficial to its market promotion.

[0027] In order to give the insulating paint high flame retardancy and improve the uniformity of dispersion of mesoporous silica hollow spheres in the insulating paint, the mesoporous silica hollow spheres were modified. Based on the boron affinity reaction mechanism, 3-aminophenylboronic acid was used to prepare boric acid-modified mesoporous silica hollow spheres, and then a bio-based flame retardant containing an ortho-dihydroxy structure was grafted to obtain a composite mesoporous silica hollow sphere with a dynamic borate ester bond, wherein the bio-based flame retardant containing an ortho-dihydroxy structure is prepared by using green raw materials vanillin and 3-chloro-1,2-propanediol to prepare vanillin-based diol, and then further synthesized with 2-aminobenzothiazole and DOPO to synthesize a bio-based flame retardant containing nitrogen, phosphorus and sulfur elements, thereby giving the insulating paint excellent resistance to mechanical damage and flame retardancy, so as to solve the problem that the insulating paint is easily damaged by external factors during long-term use and the microcracks are generated, which reduces the protective performance of the insulating paint.

[0028] In order to further improve the flame retardancy, water resistance and adhesion of insulating paint, self-healing flame retardant prepolymer is introduced into the insulating paint. Hydrogenated terminal hydroxyl polybutadiene is used as the hydrophobic soft segment and the prepolymer is synthesized with isophorone diisocyanate under the catalysis. The prepolymer is chain extended with 4,4'-diaminodiphenyl disulfide containing dynamic disulfide bonds and capped with a bio-based flame retardant containing an ortho-dihydroxy structure to prepare a water-resistant and highly adhesive self-healing flame retardant prepolymer, thereby greatly improving the various properties of the insulating paint and effectively increasing the service life of the insulating paint. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a characteristic transmission electron microscope image of the mesoporous silica hollow spheres of Example 1;

[0030] Figure 2 This is a high-magnification characteristic transmission electron microscopy image of the surface of the mesoporous silica hollow sphere in Example 1. DETAILED DESCRIPTION

[0031] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] It should be noted that if the embodiments of the present invention involve directional indications such as up, down, left, right, front, and back, the directional indication is only used to explain a specific posture such as the relative position relationship between the components, the movement status, etc. If the specific posture changes, the directional indication will also change accordingly. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0033] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0034] Example 1: A method for preparing mesoporous hollow silica spheres, comprising the following steps:

[0035] S1: 0.5 g catalyst, 0.4 g surfactant, and 100 mL ultrapure water were mixed, 40 mL organic solvent and 4 mL silicon source were added in sequence, the mixture was treated in an oil bath, and the mixture was transferred to a hydrothermal reactor for heat treatment, filtered, dried, and calcined to obtain mesoporous silica hollow spheres;

[0036] The catalyst is ethylenediamine; the surfactant is a mixture of hexadecyltrimethylammonium bromide and surfactant F127 in a mass ratio of 1:1; the organic solvent is n-hexane; and the silicon source is propyl orthosilicate;

[0037] The working conditions of oil bath insulation treatment are: temperature 30°C, time 24h; the working conditions of heat treatment are: temperature 60°C, time 24h; the working conditions of calcination are: temperature 500°C, time 5h.

[0038] Embodiment 2: A method for preparing a mesoporous hollow silica sphere insulating varnish, comprising the following steps:

[0039] S1: 0.5 g catalyst, 0.4 g surfactant, and 100 mL ultrapure water were mixed, 40 mL organic solvent and 4 mL silicon source were added in sequence, the mixture was treated in an oil bath, and the mixture was transferred to a hydrothermal reactor for heat treatment, filtered, dried, and calcined to obtain mesoporous silica hollow spheres;

[0040] The catalyst is ethylenediamine; the surfactant is a mixture of hexadecyltrimethylammonium bromide and surfactant F127 in a mass ratio of 1:1; the organic solvent is n-hexane; and the silicon source is propyl orthosilicate;

[0041] The working conditions of oil bath insulation treatment are: temperature 30℃, time 24h; the working conditions of heat treatment are: temperature 60℃, time 24h; the working conditions of roasting are: temperature 500℃, time 5h;

[0042] S2: Composite mesoporous silica hollow spheres are prepared using mesoporous silica hollow spheres, the preparation comprising the following steps:

[0043] 5 g of mesoporous silica hollow spheres and 100 mL of deionized water were mixed, 2 g of 3-aminophenylboronic acid was added, ultrasonic dispersion was performed for 1 h, stirring was performed for 10 h in the dark, centrifuged, 2.6 g of a bio-based flame retardant containing an ortho-dihydroxy structure was added, the pH value was adjusted to 9, stirring was continued for 5 h, washing and drying were performed to obtain composite mesoporous silica hollow spheres;

[0044] The preparation of the bio-based flame retardant containing an ortho-dihydroxy structure comprises the following steps:

[0045] 1) Mix 4 g of sodium hydroxide and 50 g of deionized water, transfer to a nitrogen environment at 18° C., add 0.1 mol of vanillin, stir at 78° C. for 70 min, add 0.1 mol of 3-chloro-1,2-propanediol, heat to 98° C. and stir for 4 h, extract with 80 g of n-butanol, wash with water, and rotary evaporate, recrystallize with ethyl acetate and n-hexane in a mass ratio of 1:1, filter, and dry to obtain vanillin-based diol;

[0046] 2) Under a nitrogen atmosphere, 9 g of vanillin diol, 7.5 g of 2-aminobenzothiazole, and 50 mL of anhydrous ethanol were mixed, stirred at 60 ° C for 10 h, and a mixed solution of 10.8 g of DOPO and 75 mL of anhydrous ethanol was added, and the mixture was stirred for 10 h. The mixture was filtered, washed, and dried to obtain a bio-based flame retardant;

[0047] S3: mixing epoxy resin, dispersant and solvent, adding composite mesoporous silica hollow spheres and additives, stirring and grinding, adding self-healing flame retardant prepolymer, adding curing agent, and obtaining a mesoporous silica hollow sphere insulating paint;

[0048] The preparation of the self-repairing flame-retardant prepolymer comprises the following steps: in a nitrogen atmosphere, 31 g of hydrogenated hydroxyl-terminated polybutadiene and 5 g of isophorone diisocyanate are mixed, the mixture is kept at 78° C. for 70 min, 0.18 g of dibutyltin dilaurate is added, the mixture is kept for 1 h, 2.2 g of 4,4'-diaminodiphenyl disulfide and 5 mL of anhydrous tetrahydrofuran are added, the mixture is kept for 1 h, 2 g of a bio-based flame retardant containing an ortho-dihydroxy structure and 5 mL of anhydrous tetrahydrofuran are added, the mixture is cooled to 30° C., 0.7 g of triethylamine is added, the mixture is rotary evaporated, and the material is discharged to obtain a self-repairing flame-retardant prepolymer;

[0049] The raw material composition of the insulating paint is, in parts by mass: 1 part of composite mesoporous silica hollow spheres, 20 parts of solvent, 16 parts of epoxy resin, 7 parts of self-healing flame retardant prepolymer, 1 part of dispersant, 2 parts of auxiliary agent, and 8 parts of curing agent; the auxiliary agent is a defoaming agent; and the solvent is anhydrous ethanol.

[0050] Embodiment 3: A method for preparing a mesoporous hollow silica sphere insulating varnish, comprising the following steps:

[0051] S1: 2.5 g of catalyst, 2 g of surfactant, and 100 mL of ultrapure water were mixed, and 25 mL of organic solvent and 4 mL of silicon source were added in sequence. The mixture was heat-treated in an oil bath, and then transferred to a hydrothermal reactor for heat treatment. The mixture was filtered, dried, and calcined to obtain mesoporous silica hollow spheres.

[0052] The catalyst is dodecylamine;

[0053] The surfactant is prepared by mixing octadecyltrimethylammonium chloride and surfactant P123 in a mass ratio of 3:1;

[0054] The organic solvent is octadecene; the silicon source is methyl orthosilicate;

[0055] The working conditions of oil bath heat treatment are: temperature 70℃, time 1h; the working conditions of heat treatment are: temperature 70℃, time 18h; the working conditions of roasting are: temperature 1000℃, time 1h;

[0056] S2: Composite mesoporous silica hollow spheres are prepared using mesoporous silica hollow spheres, the preparation comprising the following steps:

[0057] 5 g of mesoporous silica hollow spheres and 100 mL of deionized water were mixed, 2 g of 3-aminophenylboronic acid was added, ultrasonic dispersion was performed for 1.5 h, stirring was performed for 11 h in the dark, centrifuged, 2.6 g of a bio-based flame retardant containing an o-dihydroxy structure was added, the pH value was adjusted to 9, stirring was continued for 5.5 h, washing and drying were performed to obtain composite mesoporous silica hollow spheres;

[0058] The preparation of the bio-based flame retardant containing an ortho-dihydroxy structure comprises the following steps:

[0059] 1) Mix 4 g of sodium hydroxide and 50 g of deionized water, transfer to a nitrogen environment at 20° C., add 0.1 mol of vanillin, stir at 80° C. for 60 min, add 0.1 mol of 3-chloro-1,2-propanediol, heat to 99° C. and stir for 3.5 h, extract with 80 g of n-butanol, wash with water, and rotary evaporate, recrystallize with ethyl acetate and n-hexane in a mass ratio of 1:1, filter, and dry to obtain vanillin-based diol;

[0060] 2) Under a nitrogen atmosphere, 9 g of vanillin diol, 7.5 g of 2-aminobenzothiazole, and 50 mL of anhydrous ethanol were mixed, stirred at 63 ° C for 9 h, and a mixture of 10.8 g of DOPO and 75 mL of anhydrous ethanol was added, and the mixture was stirred for 11 h, filtered, washed, and dried to obtain a bio-based flame retardant;

[0061] S3: mixing epoxy resin, dispersant and solvent, adding composite mesoporous silica hollow spheres and additives, stirring and grinding, adding self-healing flame retardant prepolymer, adding curing agent, and obtaining a mesoporous silica hollow sphere insulating paint;

[0062] The preparation of the self-repairing flame-retardant prepolymer comprises the following steps: in a nitrogen atmosphere, 31 g of hydrogenated hydroxyl-terminated polybutadiene and 5 g of isophorone diisocyanate are mixed, the mixture is kept at 80° C. for 60 min, 0.18 g of dibutyltin dilaurate is added, the mixture is kept at 80° C. for 1.5 h, 2.2 g of 4,4'-diaminodiphenyl disulfide and 5 mL of anhydrous tetrahydrofuran are added, the mixture is kept at 80° C. for 1.5 h, 2 g of a bio-based flame retardant containing an ortho-dihydroxy structure and 5 mL of anhydrous tetrahydrofuran are added, the mixture is cooled to 33° C., 0.7 g of triethylamine is added, the mixture is rotary evaporated, and the mixture is discharged to obtain a self-repairing flame-retardant prepolymer;

[0063] The raw material composition of the insulating paint is, in parts by mass: 3 parts of composite mesoporous silica hollow spheres, 28 parts of solvent, 22 parts of epoxy resin, 11 parts of self-healing flame retardant prepolymer, 3 parts of dispersant, 3 parts of auxiliary agent, and 9 parts of curing agent; the auxiliary agent is a defoaming agent; and the solvent is anhydrous ethanol.

[0064] Embodiment 4: A method for preparing a mesoporous hollow silica sphere insulating varnish, comprising the following steps:

[0065] S1: 1.5 g catalyst, 1.5 g surfactant, and 100 mL ultrapure water were mixed, 15 mL organic solvent and 4 mL silicon source were added in sequence, the mixture was treated in an oil bath, and the mixture was transferred to a hydrothermal reactor for heat treatment, filtered, dried, and calcined to obtain mesoporous silica hollow spheres;

[0066] The catalyst is triethanolamine;

[0067] The surfactant is prepared by mixing dodecyltrimethylammonium chloride and surfactant F108 in a mass ratio of 2:1;

[0068] The organic solvent is decahydronaphthalene; the silicon source is butyl orthosilicate;

[0069] The working conditions of oil bath heat treatment are: temperature 80℃, time 22h; the working conditions of heat treatment are: temperature 80℃, time 12h; the working conditions of roasting are: temperature 750℃, time 3h;

[0070] S2: Composite mesoporous silica hollow spheres are prepared using mesoporous silica hollow spheres, the preparation comprising the following steps:

[0071] 5 g of mesoporous silica hollow spheres and 100 mL of deionized water were mixed, 2 g of 3-aminophenylboronic acid was added, ultrasonic dispersion was performed for 2 h, stirring was performed in the dark for 12 h, centrifugation was performed, 2.6 g of a bio-based flame retardant containing an o-dihydroxy structure was added, the pH value was adjusted to 9, stirring was continued for 6 h, washing and drying were performed to obtain composite mesoporous silica hollow spheres;

[0072] The preparation of the bio-based flame retardant containing an ortho-dihydroxy structure comprises the following steps:

[0073] 1) Mix 4 g of sodium hydroxide and 50 g of deionized water, transfer to a nitrogen environment at 25° C., add 0.1 mol of vanillin, stir at 82° C. for 50 min, add 0.1 mol of 3-chloro-1,2-propanediol, heat to 100° C. and stir for 3 h, extract with 80 g of n-butanol, wash with water, and rotary evaporate, recrystallize with ethyl acetate and n-hexane in a mass ratio of 1:1, filter, and dry to obtain vanillin-based diol;

[0074] 2) Under a nitrogen atmosphere, 9 g of vanillin diol, 7.5 g of 2-aminobenzothiazole, and 50 mL of anhydrous ethanol were mixed, stirred at 65 ° C for 8 h, and a mixture of 10.8 g of DOPO and 75 mL of anhydrous ethanol was added, and the mixture was stirred for 12 h, filtered, washed, and dried to obtain a bio-based flame retardant;

[0075] S3: mixing epoxy resin, dispersant and solvent, adding composite mesoporous silica hollow spheres and additives, stirring and grinding, adding self-healing flame retardant prepolymer, adding curing agent, and obtaining a mesoporous silica hollow sphere insulating paint;

[0076] The preparation of the self-repairing flame-retardant prepolymer comprises the following steps: in a nitrogen atmosphere, 31 g of hydrogenated hydroxyl-terminated polybutadiene and 5 g of isophorone diisocyanate are mixed, the mixture is kept at 82° C. for 50 min, 0.18 g of dibutyltin dilaurate is added, the mixture is kept at 82° C. for 2 h, 2.2 g of 4,4'-diaminodiphenyl disulfide and 5 mL of anhydrous tetrahydrofuran are added, the mixture is kept at 82° C. for 2 h, 2 g of a bio-based flame retardant containing an ortho-dihydroxy structure and 5 mL of anhydrous tetrahydrofuran are added, the mixture is cooled to 35° C., 0.7 g of triethylamine is added, the mixture is rotary evaporated, and the mixture is discharged to obtain a self-repairing flame-retardant prepolymer;

[0077] The raw material composition of the insulating paint is, in parts by mass: 5 parts of composite mesoporous silica hollow spheres, 35 parts of solvent, 26 parts of epoxy resin, 13 parts of self-healing flame retardant prepolymer, 5 parts of dispersant, 5 parts of auxiliary agent, and 15 parts of curing agent; the auxiliary agent is a defoaming agent; and the solvent is anhydrous ethanol.

[0078] Comparative Example 1: Taking Example 4 as the control group, the composite mesoporous silica hollow spheres were replaced with mesoporous silica hollow spheres, and the other processes were normal.

[0079] Comparative Example 2: Example 4 was used as the control group, and no self-repairing flame-retardant prepolymer was prepared, and other processes were normal.

[0080] Sources of raw materials used (for demonstration purposes only):

[0081] Defoamer TL-J20: Shenzhen Jihechang New Materials Co., Ltd.; methyl orthosilicate 681-84-5, dispersant NNOT25140: Shanghai Yuanye Biotechnology Co., Ltd.; epoxy resin E51 (99%): Jinan Chuangshi Chemical Co., Ltd.; curing agent (650 low molecular weight polyamide): Wuhan Jiyesheng Chemical Co., Ltd.; propyl orthosilicate 682-01-9: Hubei Fangde New Materials Co., Ltd.; hydrogenated hydroxyl-terminated polybutadiene GI-3000 (HHPB, industrial grade): Japan Soda Co., Ltd.; surfactant F108 (Pluronic F108): BASF; Surfactant F-127R1837, Surfactant P123R1837-1: Nanjing Dulai Biotechnology Co., Ltd.; Ethylenediamine E112132, Dodecylamine D113939, Triethanolamine T108151, Butyl Orthosilicate T161830, Dodecyltrimethylammonium Chloride D298576, Octadecyltrimethylammonium Chloride S105314, Hexadecyltrimethylammonium Bromide H108983, 3-Aminophenylboronic Acid A101981, Vanillin V100115, 3-Chloro-1,2-Propanediol C117 659, 2-aminobenzothiazole A110691, DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) D102416, isophorone diisocyanate I109582, dibutyltin dilaurate D100274, 4,4'-diaminodiphenyl disulfide A101817, tetrahydrofuran T103263, triethylamine T103285, decahydronaphthalene D119689, octadecene O109487: Aladdin reagent; n-hexane, sodium hydroxide, n-butanol, ethyl acetate, anhydrous ethanol, analytical grade: Sinopharm reagent.

[0082] Performance test: The insulating varnishes prepared in Examples 2-4 and Comparative Examples 1-2 were tested:

[0083] Sample: The insulating paint is cured on the surface of a steel plate with a length of 100 mm, a width of 90 mm, and a thickness of 0.12 mm. Electrical insulation: The electrical strength test is carried out with reference to GB / T1981.2-2009. Self-healing rate: A scratch with a length of 1 mm, a width of 2 μm, and a depth of 80 μm is made on the sample, and the scratch length is observed with an electron microscope at 60°C for 12 hours. The self-healing rate = (L 初始 -L 现有 ) / L 初始 ×100%; Flame retardancy: The sample was subjected to UL-94 vertical combustion test for flame retardancy; Water resistance: The sample was placed at 220℃ for 6 hours, cooled and then immersed in deionized water at 25℃ for 168 hours to observe whether peeling, blistering, breakage, etc. occurred. If there was no peeling, blistering, breakage, etc., the sample was qualified. The results are shown in Table 1;

[0084] Table 1

[0085] Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Electrical strength / (kV / mm) 68 69 70 57 62 Self-healing rate (%) 99.9 99.9 100 91.2 89.5 Flame retardant grade V-0 V-0 V-0 V-1 V-1 Water resistance qualified qualified qualified Failure Failure

[0086] The invention provides a method for preparing a mesoporous silica hollow ball insulating varnish, optimizes its components, and prepares a multifunctional insulating varnish which is resistant to high temperatures, highly flame-retardant and self-repairing.

[0087] By comparing Example 4 with Comparative Example 1, it can be seen that in order to give the insulating paint high temperature resistance and high flame retardancy and improve the uniformity of dispersion of mesoporous silica hollow spheres in the insulating paint, the mesoporous silica hollow spheres are modified. Based on the boron affinity reaction mechanism, 3-aminophenylboronic acid is used to prepare boric acid-modified mesoporous silica hollow spheres, and then a bio-based flame retardant containing an ortho-dihydroxy structure is grafted to obtain a composite mesoporous silica hollow sphere with a dynamic borate ester bond, wherein the bio-based flame retardant containing an ortho-dihydroxy structure is prepared by preparing vanillin-based diol with green raw materials vanillin and 3-chloro-1,2-propanediol, and then further synthesizing a bio-based flame retardant containing nitrogen, phosphorus and sulfur elements with 2-aminobenzothiazole and DOPO, thereby giving the insulating paint excellent resistance to mechanical damage and flame retardancy, so as to solve the problem that the insulating paint is easily damaged by external factors during long-term use and the microcracks generated, which reduces the protective performance of the insulating paint.

[0088] By comparing Example 4 with Comparative Example 2, it can be seen that in order to further improve the flame retardancy, water resistance and adhesion of the insulating paint, a self-healing flame retardant prepolymer is introduced into the insulating paint, and hydrogenated terminal hydroxyl polybutadiene is used as the hydrophobic soft segment. The prepolymer is synthesized under the catalysis of isophorone diisocyanate, and the prepolymer is chain extended with 4,4′-diaminodiphenyl disulfide containing a dynamic disulfide bond, and the prepolymer is end-capped with a bio-based flame retardant containing an ortho-dihydroxy structure to prepare a water-resistant, highly adhesive self-healing flame retardant prepolymer, thereby greatly improving the various properties of the insulating paint and effectively increasing the service life of the insulating paint.

[0089] The above descriptions are only embodiments of the present invention and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the present invention specification under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for preparing hollow mesoporous silica spheres, characterized in that: The following steps are involved: The catalyst, surfactant and ultrapure water are mixed, and an organic solvent and a silicon source are added in sequence, and the mixture is heat-treated in an oil bath, and the mixture is transferred to a hydrothermal kettle for heat treatment, filtered, dried and calcined to obtain mesoporous silica hollow spheres.

2. The method for preparing mesoporous hollow silica spheres according to claim 1, characterized in that: The catalyst is one or a combination of ammonia water, ethylenediamine, dodecylamine, triethanolamine and diethanolamine.

3. The method for preparing hollow mesoporous silica spheres according to claim 1, characterized in that: The surfactant is a cationic surfactant and a nonionic surfactant mixed in a mass ratio of (1-3):1; the organic solvent is a mixture of one or more of dioxane, cyclohexane, n-hexane, octadecene, and decahydronaphthalene; and the silicon source is a mixture of one or more of methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, and butyl orthosilicate.

4. The method for preparing hollow mesoporous silica spheres according to claim 1, characterized in that: The working conditions of oil bath insulation treatment are: temperature 30-80℃, time 22-24h; the working conditions of heat treatment are: temperature 60-80℃, time 12-24h; the working conditions of roasting are: temperature 500-1000℃, time 1-5h.

5. A method for preparing mesoporous silica hollow sphere insulating varnish, characterized in that: The mesoporous silica hollow spheres prepared by the preparation method according to any one of claims 1 to 4 are prepared, comprising the following steps: S1: Preparation of composite mesoporous silica hollow spheres using mesoporous silica hollow spheres; S2: Mix epoxy resin, dispersant and solvent, add composite mesoporous silica hollow spheres and additives, stir and grind, add self-healing prepolymer, add curing agent, and obtain a mesoporous silica hollow sphere insulating paint.

6. The method for preparing a mesoporous hollow silica sphere insulating varnish according to claim 5, characterized in that: The insulating paint comprises, by weight, 1-5 parts of composite mesoporous hollow silica spheres, 20-35 parts of solvent, 16-26 parts of epoxy resin, 7-13 parts of self-healing flame-retardant prepolymer, 1-5 parts of dispersant, 2-5 parts of auxiliary agent and 8-15 parts of curing agent.

7. The method for preparing a mesoporous hollow silica sphere insulating varnish according to claim 5, characterized in that: The auxiliary agent is one or more of a defoamer, a film former, a leveling agent, an anti-settling agent, and a wetting agent; and the solvent is one or more of a defoamer, anhydrous ethanol, methanol, and N,N-dimethylacetamide.

8. The method for preparing a mesoporous hollow silica sphere insulating varnish according to claim 5, characterized in that: The preparation of the composite mesoporous silica hollow spheres comprises the following steps: The mesoporous silica hollow spheres and deionized water are mixed, 3-aminophenylboric acid is added, ultrasonic dispersion is performed for 1-2 hours, stirring is performed for 10-12 hours in a dark environment, centrifugation is performed, a bio-based flame retardant containing an ortho-dihydroxy structure is added, the pH value is adjusted to 9, stirring is continued for 5-6 hours, washing and drying are performed to obtain composite mesoporous silica hollow spheres.

9. According to the method for preparing a mesoporous hollow silica sphere insulating varnish according to claim 5, the preparation of the self-repairing flame-retardant prepolymer comprises the following steps: In a nitrogen atmosphere, hydrogenated hydroxy-terminated polybutadiene and isophorone diisocyanate are mixed, kept warm at 78-82°C for 50-70 minutes, dibutyltin dilaurate is added, and the heat preservation is continued for 1-2 hours, a mixed solution of 4,4'-diaminodiphenyl disulfide and anhydrous tetrahydrofuran is added, and the heat preservation is continued for 1-2 hours, a mixed solution of a bio-based flame retardant containing an ortho-dihydroxy structure and anhydrous tetrahydrofuran is added, the temperature is lowered to 30-35°C, triethylamine is added, rotary evaporation is performed, and the material is discharged to obtain a self-repairing flame retardant prepolymer.

10. The method for preparing a mesoporous hollow silica sphere insulating varnish according to claim 8 or 9, characterized in that: The preparation of the bio-based flame retardant containing an ortho-dihydroxy structure comprises the following steps: 1) Mix sodium hydroxide and deionized water, transfer to a nitrogen environment at 18-25° C., add vanillin, stir at 78-82° C. for 50-70 min, add 3-chloro-1,2-propanediol, heat to 98-100° C. and stir for 3-4 h, extract with n-butanol, wash with water, and rotary evaporate, recrystallize with ethyl acetate and n-hexane in a mass ratio of 1:1, filter, and dry to obtain vanillin-based diol; 2) Under a nitrogen atmosphere, vanillin diol, 2-aminobenzothiazole and anhydrous ethanol are mixed, stirred at 60-65° C. for 8-10 hours, a mixed solution of DOPO and anhydrous ethanol is added, and stirring is continued for 10-12 hours. The mixture is filtered, washed and dried to obtain a bio-based flame retardant containing an ortho-dihydroxy structure.

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