Two-component high-hydrophobicity PRTV coating and preparation method thereof

Abstract

The invention belongs to the technical field of organic silicon coatings and electrical functional materials, and discloses a two-component high-hydrophobicity PRTV coating and a preparation method thereof. The two-component high-hydrophobicity PRTV coating is composed of a component A and a component B. The component A comprises the following components in parts by weight: 50-150 parts of alpha, omega-dihydroxy polysiloxane, 80-100 parts of dimethyl silicone oil, 2-7 parts of titanium dioxide, 20-40 parts of flame-retardant powder, 10-15 parts of fumed silica, 10-50 parts of nano calcium carbonate, 0.2-2 parts of an antistatic agent and 20-50 parts of fluorine-containing silicon resin. The component B comprises the following components in parts by weight: 10-30 parts of a cross-linking agent, 10-20 parts of a No.3 waterproof agent, 0.5-3 parts of a silane coupling agent, 2-10 parts of dimethyl silicone oil and 0.02-0.1 part of a catalyst. The PRTV coating disclosed by the invention has remarkably improved hydrophobic and anti-fouling performance, mechanical properties of a coating and component stability.

Description

Technical Field

[0001] The invention belongs to the technical field of organic silicon coatings and electrical functional materials, and specifically relates to a two-component highly hydrophobic PRTV coating and a preparation method thereof. Background Art

[0002] PRTV coating, the full name of which is durable in-situ formed anti-pollution flashover composite coating for external insulation of power equipment, is a new type of electrical functional material. Its main function is to prevent pollution flashover accidents in power equipment and ensure the safe and stable operation of the power system.

[0003] Silicone rubber has been widely used in PRTV coatings because of its good hydrophobicity, weather resistance, and high electrical insulation performance. For example, patents CN 102702974 A and CN 105086824 A both disclose PRTV long-lasting anti-fouling flashover coatings prepared by cross-linking end-hydroxy polydimethylsiloxane. However, the hydrophobicity of pure silicone rubber is limited. When it rains, many water droplets cannot slide away easily, which can easily cause electrical short circuits. Its hydrophobicity can be enhanced by adding fluorine-containing resins. For example, patent CN108641439A discloses a PRTV durable anti-fouling flashover coating, which improves its pollution resistance by adding fluorocarbon resins, difluoroethylene, tetrafluoroethylene, and hexafluoropropylene. However, the above-mentioned fluorine-containing resins or fluorine-containing compounds have poor compatibility with the silicone rubber matrix, and the migration speed of small molecule fluorine-containing compounds is too fast, resulting in poor pollution resistance and durability. Summary of the invention

[0004] In view of the shortcomings and deficiencies of the above prior art, the primary purpose of the present invention is to provide a two-component highly hydrophobic PRTV coating.

[0005] Another object of the present invention is to provide a method for preparing the above-mentioned two-component highly hydrophobic PRTV coating.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A two-component highly hydrophobic PRTV coating, consisting of component A and component B, wherein component A includes the following components in parts by weight:

[0008] 50-150 parts of α,ω-dihydroxy polysiloxane, 80-100 parts of dimethyl silicone oil, 2-7 parts of titanium dioxide, 20-40 parts of flame retardant powder, 10-15 parts of fumed silica, 10-50 parts of nano calcium carbonate, 0.2-2 parts of antistatic agent, 20-50 parts of fluorine-containing silicone resin;

[0009] The B component includes the following components in parts by weight:

[0010] 10-30 parts of cross-linking agent, 10-20 parts of No. 3 waterproofing agent (polymethyltriethoxysilane), 0.5-3 parts of silane coupling agent, 2-10 parts of dimethyl silicone oil, and 0.02-0.1 parts of catalyst.

[0011] Furthermore, the viscosity of the α,ω-dihydroxy polysiloxane is 200 to 5000 mPa·s; the viscosity of the dimethyl silicone oil in component A and component B is 10 to 1000 mPa·s.

[0012] Furthermore, the flame retardant powder is at least one of aluminum hydroxide, magnesium hydroxide, sodium tripolyphosphate, sodium hexametaphosphate, triphenyl phosphate, and ammonium polyphosphate.

[0013] Furthermore, the antistatic agent is at least one of stearamidopropyl hydroxyethyl quaternary ammonium nitrate, alkyl dicarboxymethyl ammonium betaine, and dodecyl dimethyl quaternary betaine.

[0014] Furthermore, the fluorine-containing silicone resin is polytrifluoropropylmethylsiloxane, polymethylnonafluorohexylsiloxane, polyheptadecafluoromethylsiloxane or a specific alkoxy-modified fluorine-containing polysiloxane; preferably alkoxy-modified fluorine-containing polysiloxane; the alkoxy-modified fluorine-containing polysiloxane is prepared by the following method:

[0015] Hydrogen-containing silicone oil, a fluorine-containing monomer containing an unsaturated double bond, and a silane coupling agent containing an unsaturated double bond are added to an organic solvent and mixed evenly, the temperature is raised to 70-100° C., and after deoxygenation and dehydration with nitrogen, a chloroplatinic acid catalyst solution is added and stirred to react until the unsaturated double bond reaction is complete, and the organic solvent is removed under reduced pressure to obtain an alkoxy-modified fluorine-containing polysiloxane.

[0016] The alkoxy-modified fluorinated polysiloxane has the following molecular structure:

[0017]

[0018] In the above structural formula, -R f represents a fluorine-containing group, -OR represents an alkoxy group, and R1 and R2 represent connecting groups after silylation; wherein a, b, m, and n can be adjusted according to the molecular weight and hydrogen content of the hydrogen-containing silicone oil, and the added ratio of the fluorine-containing monomer containing an unsaturated double bond and the silane coupling agent containing an unsaturated double bond.

[0019] In the preparation of the above-mentioned alkoxy-modified fluorinated polysiloxane, the viscosity of the hydrogen-containing silicone oil is 100-1000 mPa·s (25° C.), and the hydrogen content is 0.3-1.5 wt.%; the fluorinated monomer containing unsaturated double bonds is perfluoroalkyl ethylene, perfluoroalkyl vinyl ether or perfluoroalkyl acrylate; the silane coupling agent containing unsaturated double bonds is vinyl trimethoxy silane, vinyl triethoxy silane, methacryloxypropyl trimethoxy silane or methacryloxypropyl triethoxy silane; the molar ratio of the hydrogen-containing silicone oil to the fluorinated monomer containing unsaturated double bonds and the silane coupling agent containing unsaturated double bonds is 1:0.1-0.5:0.1-0.5 based on the hydrogen content.

[0020] Furthermore, the crosslinking agent is methyl orthosilicate, ethyl orthosilicate or a specific cyclosiloxane crosslinking agent; preferably a cyclosiloxane crosslinking agent; the cyclosiloxane crosslinking agent is prepared by the following method:

[0021] The hydrogen-containing ring body and the vinyl silane coupling agent are mixed and reacted under the condition of a hydrosilylation catalyst to obtain a cyclosiloxane crosslinking agent.

[0022] In the preparation of the above-mentioned cyclosiloxane crosslinking agent, the hydrogen-containing ring body is tetramethylhydrogencyclotetrasiloxane (D4H) or pentamethylhydrogencyclopentasiloxane (D5H); the molar ratio of the reaction of the hydrogen-containing ring body and the vinyl silane coupling agent is 1:2-5; the vinyl silane coupling agent is vinyltrimethoxysilane or vinyltriethoxysilane; the mixed reaction is carried out under solvent-free conditions or anhydrous solvent conditions, and the anhydrous solvent is one or a mixed solvent of two or more of ethanol, isopropanol, acetone, benzene, toluene, ethyl acetate, cyclohexane, dimethylformamide, and dimethyl sulfoxide; the hydrosilylation catalyst is an isopropanol solution of chloroplatinic acid (Speier catalyst) or a vinyl platinum complex (Karstedt's catalyst); the temperature of the mixed reaction is 70-90°C and the time is 2-8h.

[0023] The preparation of the cyclosiloxane crosslinking agent includes the following reaction formula:

[0024]

[0025] Furthermore, the silane coupling agent is at least one of KH-550 (γ-aminopropyltriethoxysilane) and KH-560 (γ-glycidyloxypropyltrimethoxysilane).

[0026] Furthermore, the catalyst is an organotin catalyst.

[0027] The preparation method of the above two-component highly hydrophobic PRTV coating comprises the following preparation steps:

[0028] (1) α,ω-dihydroxy polysiloxane is mixed with nano calcium carbonate, titanium dioxide, flame retardant powder and fumed silica, and then dimethyl silicone oil, fluorine-containing silicone resin and antistatic agent are added and mixed to obtain a base material of component A;

[0029] (2) The crosslinking agent, No. 3 waterproofing agent and silane coupling agent are mixed evenly under closed anhydrous conditions, and then the catalyst and dimethyl silicone oil are added and mixed evenly to obtain the B component base material.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The present invention can significantly improve the hydrophobic and anti-fouling properties of PRTV coatings by adding fluorine-containing silicone resins. Compared with existing fluorocarbon resins and fluorine-containing compounds, the fluorine-containing silicone resins used have better compatibility with silicone rubber substrates, and can thus better exert their hydrophobic and anti-fouling properties. And by further using alkoxy-modified fluorine-containing polysiloxanes, the alkoxy groups contained therein can be chemically cross-linked with α,ω-dihydroxy polysiloxanes, further improving the compatibility and bonding strength between the fluorine-containing component and the silicone rubber component, thereby improving the hydrophobic and anti-fouling properties and the mechanical properties of the coating.

[0032] (2) The present invention further adopts a specific cyclosiloxane crosslinking agent, whose highly hindered ring structure can effectively reduce the self-condensation tendency of the crosslinking agent and significantly enhance the storage stability of the coating component. At the same time, it has better compatibility with α,ω-dihydroxy polysiloxane and more crosslinking active sites, so it can significantly improve the crosslinking efficiency with linear α,ω-dihydroxy polysiloxane, thereby improving the mechanical properties of the coating. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

[0034] Example 1

[0035] A two-component highly hydrophobic PRTV coating, consisting of component A and component B, wherein component A includes the following components in parts by weight:

[0036] 100 parts of α,ω-dihydroxypolysiloxane (viscosity is 2000mPa·s), 90 parts of dimethyl silicone oil (viscosity is 200mPa·s), 5 parts of titanium dioxide, 30 parts of aluminum hydroxide flame retardant powder, 12 parts of fumed silica, 25 parts of nano calcium carbonate, 1 part of antistatic agent dodecyl dimethyl quaternary ethyl salt, and 35 parts of polymethyl nonafluorohexylsiloxane.

[0037] The B component includes the following components in parts by weight:

[0038] 20 parts of ethyl orthosilicate crosslinking agent, 15 parts of No. 3 waterproofing agent, 1 part of KH-550 silane coupling agent, 0.5 parts of KH-560 silane coupling agent, 6 parts of dimethyl silicone oil (viscosity 200mPa·s), and 0.05 parts of dibutyltin dilaurate catalyst.

[0039] The preparation method of the two-component highly hydrophobic PRTV coating comprises the following steps:

[0040] (1) α,ω-dihydroxy polysiloxane is stirred and mixed with nano calcium carbonate, titanium dioxide, flame retardant powder and fumed silica under heating conditions, and then dimethyl silicone oil, fluorine-containing silicone resin and antistatic agent are added and mixed to obtain component A base material.

[0041] (2) The crosslinking agent, No. 3 waterproofing agent and silane coupling agent are mixed evenly under closed anhydrous conditions, and then the catalyst and dimethyl silicone oil are added and mixed evenly to obtain the B component base material.

[0042] Example 2

[0043] A two-component highly hydrophobic PRTV coating, consisting of component A and component B, wherein component A includes the following components in parts by weight:

[0044] 50 parts of α,ω-dihydroxypolysiloxane (viscosity is 1000mPa·s), 100 parts of dimethyl silicone oil (viscosity is 600mPa·s), 7 parts of titanium dioxide, 20 parts of aluminum hydroxide flame retardant powder, 15 parts of fumed silica, 10 parts of nano calcium carbonate, 1 part of antistatic agent stearamidopropyl hydroxyethyl quaternary ammonium nitrate, and 20 parts of polytrifluoropropyl methylsiloxane.

[0045] The B component includes the following components in parts by weight:

[0046] 10 parts of ethyl orthosilicate crosslinking agent, 20 parts of No. 3 waterproofing agent, 0.5 parts of KH-550 silane coupling agent, 0.2 parts of KH-560 silane coupling agent, 2 parts of dimethyl silicone oil (viscosity 600mPa·s), and 0.05 parts of dibutyltin dilaurate catalyst.

[0047] Example 3

[0048] A two-component highly hydrophobic PRTV coating, consisting of component A and component B, wherein component A includes the following components in parts by weight:

[0049] 150 parts of α,ω-dihydroxypolysiloxane (viscosity 4000mPa·s), 80 parts of dimethyl silicone oil (viscosity 100mPa·s), 2 parts of titanium dioxide, 40 parts of aluminum hydroxide flame retardant powder, 10 parts of fumed silica, 50 parts of nano calcium carbonate, 1 part of antistatic agent alkyl dicarboxymethyl ammonium ethyl lactone, and 50 parts of polyheptadecafluoromethyl methylsiloxane.

[0050] The B component includes the following components in parts by weight:

[0051] 30 parts of ethyl orthosilicate crosslinking agent, 10 parts of No. 3 waterproofing agent, 2 parts of KH-550 silane coupling agent, 1 part of KH-560 silane coupling agent, 10 parts of dimethyl silicone oil (viscosity of 100mPa·s), and 0.05 parts of dibutyltin dilaurate catalyst.

[0052] Example 4

[0053] A two-component highly hydrophobic PRTV coating, compared with Example 1, the polymethyl nonafluorohexylsiloxane in component A is replaced by a specific alkoxy-modified fluorinated polysiloxane; the alkoxy-modified fluorinated polysiloxane is prepared by the following method:

[0054] Hydrogenated silicone oil with a viscosity of 400 mPa·s (25° C.) and a hydrogen content of 0.9 wt.% is added to toluene, mixed evenly, and heated to 90° C. After nitrogen deoxygenation and dehydration, a catalytic amount of chloroplatinic acid isopropanol solution is added, stirred and reacted for 3 hours until the double bond reaction is complete, and the toluene solvent is removed by reduced pressure distillation to obtain an alkoxy-modified fluorinated polysiloxane. The molar ratio of the hydrogenated silicone oil to perfluorooctylethylene and vinyl triethoxysilane is 1:0.3:0.3 based on the hydrogen content.

[0055] Example 5

[0056] A two-component highly hydrophobic PRTV coating, compared with Example 1, the tetraethyl orthosilicate crosslinking agent in component B is replaced by a specific cyclosiloxane crosslinking agent; the cyclosiloxane crosslinking agent is prepared by the following method:

[0057] D4H and vinyltrimethoxysilane were added into the reactor in a molar ratio of 1:4 and mixed evenly. After nitrogen substitution, the temperature was raised to 70-80°C. Speier catalyst was added dropwise and stirred for 4 hours. The vinyl content in the product was detected by sampling and the addition reaction rate was calculated to be 98.6%. The temperature was raised to 100-110°C to remove the residual solvent and unreacted raw materials in vacuum to obtain a cyclosiloxane crosslinking agent.

[0058] Comparative Example 1

[0059] A two-component highly hydrophobic PRTV coating, compared with Example 1, the polymethyl nonafluorohexylsiloxane in component A is replaced by fluorocarbon resin (polytetrafluoroethylene powder).

[0060] The hydrophobicity (water contact angle test), hydrophobicity durability (water contact angle test after high temperature and high humidity treatment at 60°C, 90% RH, 160h), adhesion (GB / T 9286-2021), mechanical properties (GB / T 528-2009) and storage stability (the coating component B was sealed and placed in an 80°C oven for accelerated aging for 48h, then taken out and placed under standard conditions (temperature 25°C, relative humidity 55%) for 24h to test the mechanical properties of the coating after vulcanization) of the highly hydrophobic PRTV coating obtained in the above Example 1, Examples 4 to 5 and Comparative Example 1 on the power ceramic insulator substrate were tested, and the results are shown in Table 1 below.

[0061] Table 1

[0062]

[0063] It can be seen from the comparison results of Example 1 and Comparative Example 1 in Table 1 that the present invention uses fluorosilicone resin as a hydrophobic modifier for PRTV coatings, which can significantly improve the hydrophobicity, hydrophobic durability, adhesion and mechanical properties of the coating compared to conventional fluorocarbon resins. It can be seen from the comparison results of Example 4 and Example 1 that the use of specific alkoxy-modified fluorinated polysiloxanes can further improve the hydrophobicity, hydrophobic durability and mechanical properties compared to fluorosilicone resins without coupling groups. It can be seen from the comparison results of Example 5 and Example 1 that the use of specific cyclosiloxane crosslinkers can significantly improve the storage stability of the crosslinking component of the obtained coating compared to tetraethyl orthosilicate crosslinkers. Example 1 and Comparative Example 1 use tetraethyl orthosilicate crosslinkers, which basically lose their vulcanization properties after accelerated aging. Example 4 has certain vulcanization properties because it uses alkoxy-modified fluorinated polysiloxanes with crosslinking properties.

[0064] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A two-component highly hydrophobic PRTV coating, characterized in that: It is composed of component A and component B, wherein component A includes the following components in parts by weight: 50-150 parts of α,ω-dihydroxy polysiloxane, 80-100 parts of dimethyl silicone oil, 2-7 parts of titanium dioxide, 20-40 parts of flame retardant powder, 10-15 parts of fumed silica, 10-50 parts of nano calcium carbonate, 0.2-2 parts of antistatic agent, 20-50 parts of fluorine-containing silicone resin; The B component includes the following components in parts by weight: 10-30 parts of cross-linking agent, 10-20 parts of No. 3 waterproofing agent, 0.5-3 parts of silane coupling agent, 2-10 parts of dimethyl silicone oil, and 0.02-0.1 parts of catalyst.

2. A two-component highly hydrophobic PRTV coating according to claim 1, characterized in that: The viscosity of the α,ω-dihydroxy polysiloxane is 200 to 5000 mPa·s; the viscosity of the dimethyl silicone oil in the A component and the B component is 10 to 1000 mPa·s.

3. A two-component highly hydrophobic PRTV coating according to claim 1, characterized in that: The flame retardant powder is at least one of aluminum hydroxide, magnesium hydroxide, sodium tripolyphosphate, sodium hexametaphosphate, triphenyl phosphate, and ammonium polyphosphate; the antistatic agent is at least one of stearamidopropyl hydroxyethyl quaternary ammonium nitrate, alkyl dicarboxymethyl ammonium ethyl lactone, and dodecyl dimethyl quaternary ethyl lactone.

4. A two-component highly hydrophobic PRTV coating according to claim 1, characterized in that: The fluorine-containing silicone resin is polytrifluoropropylmethylsiloxane, polymethylnonafluorohexylsiloxane, polyheptadecafluoromethylsiloxane or alkoxy-modified fluorine-containing polysiloxane; the alkoxy-modified fluorine-containing polysiloxane is prepared by the following method: Hydrogen-containing silicone oil, a fluorine-containing monomer containing an unsaturated double bond, and a silane coupling agent containing an unsaturated double bond are added to an organic solvent and mixed evenly, the temperature is raised to 70-100° C., and after deoxygenation and dehydration with nitrogen, a chloroplatinic acid catalyst solution is added and stirred to react until the unsaturated double bond reaction is complete, and the organic solvent is removed under reduced pressure to obtain an alkoxy-modified fluorine-containing polysiloxane.

5. A two-component highly hydrophobic PRTV coating according to claim 4, characterized in that: The viscosity of the hydrogen-containing silicone oil is 100-1000 mPa·s, and the hydrogen content is 0.3-1.5 wt.%; the fluorine-containing monomer containing unsaturated double bonds is perfluoroalkyl ethylene, perfluoroalkyl vinyl ether or perfluoroalkyl acrylate; the silane coupling agent containing unsaturated double bonds is vinyl trimethoxy silane, vinyl triethoxy silane, methacryloxypropyl trimethoxy silane or methacryloxypropyl triethoxy silane; the molar ratio of the hydrogen-containing silicone oil to the fluorine-containing monomer containing unsaturated double bonds and the silane coupling agent containing unsaturated double bonds is 1:0.1-0.5:0.1-0.5 based on the hydrogen content.

6. A two-component highly hydrophobic PRTV coating according to claim 1, characterized in that: The crosslinking agent is methyl orthosilicate, ethyl orthosilicate or cyclosiloxane crosslinking agent; the cyclosiloxane crosslinking agent is prepared by the following method: The hydrogen-containing ring body and the vinyl silane coupling agent are mixed and reacted under the condition of a hydrosilylation catalyst to obtain a cyclosiloxane crosslinking agent.

7. A two-component highly hydrophobic PRTV coating according to claim 6, characterized in that: The hydrogen-containing ring body is tetramethylhydrogencyclotetrasiloxane or pentamethylhydrogencyclopentasiloxane; the molar ratio of the hydrogen-containing ring body to the vinyl silane coupling agent is 1:2-5; the vinyl silane coupling agent is vinyltrimethoxysilane or vinyltriethoxysilane; the mixed reaction is carried out under solvent-free conditions or anhydrous solvent conditions, and the anhydrous solvent is one or a mixed solvent of two or more of ethanol, isopropanol, acetone, benzene, toluene, ethyl acetate, cyclohexane, dimethylformamide, and dimethyl sulfoxide; the hydrosilylation catalyst is a Speier catalyst or a Karstedt's catalyst; the temperature of the mixed reaction is 70-90°C and the time is 2-8h.

8. A two-component highly hydrophobic PRTV coating according to claim 1, characterized in that: The silane coupling agent is at least one of KH-550 and KH-560.

9. A two-component highly hydrophobic PRTV coating according to claim 1, characterized in that: The catalyst is an organotin catalyst.

10. A method for preparing a two-component highly hydrophobic PRTV coating according to any one of claims 1 to 9, characterized in that: The method comprises the following preparation steps: (1) α,ω-dihydroxy polysiloxane is mixed with nano calcium carbonate, titanium dioxide, flame retardant powder and fumed silica, and then dimethyl silicone oil, fluorine-containing silicone resin and antistatic agent are added and mixed to obtain a base material of component A; (2) The crosslinking agent, No. 3 waterproofing agent and silane coupling agent are mixed evenly under closed anhydrous conditions, and then the catalyst and dimethyl silicone oil are added and mixed evenly to obtain the B component base material.

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