A polymer nano-insulating self-cleaning material and its preparation method

Abstract

This invention belongs to the field of organic coatings, specifically relating to a polymeric nano-insulating self-cleaning material, composed of the following components by weight: 100 parts α,ω-dihydroxypolysiloxane; 2-8 parts polydimethylsiloxane; 2-6 parts titanium dioxide; 30-60 parts flame retardant powder; 10-20 parts fumed silica; 10-30 parts nano-calcium carbonate; 1-6 parts antistatic agent; 15-30 parts fluorosilicone resin; 2-6 parts silane coupling agent; 0.2-0.5 parts crosslinking agent; and 20-30 parts diluent. The crosslinking agent is composed of tetrabutylone oxime silane and methyltributanone oxime silane in a weight ratio of 3-5:1. It exhibits excellent fast-drying properties, anti-flashover ability, excellent adhesion and bonding strength, and maintains superhydrophobicity and self-cleaning properties for a long time. A second objective of this invention is to provide a method for preparing the above-mentioned organosilicon coating.

Description

Technical Field

[0001] This invention belongs to the field of organosilicon, specifically relating to a polymer nano-insulating self-cleaning material and its preparation method. Background Technology

[0002] Currently, insulators on railway lines and trains are coated with anti-flashover paint to ensure cleanliness and prevent flashover. The base material of PRTV anti-flashover paint is a special siloxane polymer compound with a Si-O-Si molecular chain and CH2 substituents or side chains. The methyl groups (organic groups) in the polysiloxane molecule are connected to the main chain, forming an inverted tetrahedral umbrella-shaped spatial configuration outside the Si atoms. Since H atoms have the smallest van der Waals atomic radius, the umbrella-shaped methyl structures they form are tightly arranged together, creating a closed barrier that keeps water molecules out. When rainwater or dew comes into contact with the coating surface, it turns into droplets that automatically roll off or scatter on the coating surface, preventing the formation of continuous water chains or spreading into a water film, thus exhibiting extremely excellent hydrophobic properties.

[0003] PRTV coating possesses excellent water-repellent and hydrophobic migration properties, while also exhibiting some oleophobicity and good non-stickiness. Under harsh climatic conditions, a continuous water film can form along the surface of a damp and dirty insulator, leading to flashover. When PRTV coating is applied, its hydrophobic migration properties make the surface of the contaminant layer also hydrophobic. Only discontinuous small water droplets exist on the surface of the contaminant layer, preventing wetting and clogging, thus greatly improving the anti-flashover performance of the power equipment. Hydrophobic substances alone are insufficient for use as anti-flashover coatings for insulators; excellent hydrophobic migration properties are also necessary. When contaminants accumulate on the surface, the free hydrophobic substances within the PRTV gradually extend to the contaminant surface, making the contaminant layer hydrophobic as well. It is not wetted by rainwater or moisture in fog, nor is it ionized, thus effectively suppressing leakage current and greatly improving the insulator's anti-flashover capability. Therefore, hydrophobic migration properties are one of the key indicators of the anti-flashover performance of PRTV coating.

[0004] Since hydrophobic migration requires a process, this process can also lead to a decrease in the anti-flashover performance of insulators, resulting in an increasing demand for self-cleaning coatings that are non-dust-adhesive or have low dust-adhesive properties.

[0005] The applicant previously filed a patent application CN116218365A, which disclosed an organosilicon coating and its preparation method. The formulation is as follows: 30-50 parts of Shin-Etsu KP-549 acrylate / polydimethylsiloxane copolymer, 50-100 parts of low-viscosity α,ω-dihydroxypolysiloxane, 2-10 parts of polydimethylsiloxane, 10-30 parts of white oil, 20-40 parts of fumed silica, 10-15 parts of polymethylnonafluorohexylsiloxane, 10-40 parts of methoxyPEG-10propyltrimethoxysilane, 2-5 parts of crosslinking agent, 0.5-1 part of coupling agent, 0.01-0.05 parts of catalyst, and 100-300 parts of solvent oil.

[0006] The viscosity of the low-viscosity α,ω-dihydroxy polysiloxane is 1000 mPa·s to 5000 mPa·s; the relative molecular mass of the polydimethylsiloxane is 20000 to 50000.

[0007] The viscosity of the polymethylnonafluorohexylsiloxane is 3000-7500 mPa·s. The coupling agent is a mixture of isopropyltriisostearate titanate and γ-methacryloyloxypropyltrimethoxysilane in a mass ratio of 3:2.

[0008] This coating is mainly used in electrical boxes, so it is more important to test its protective function under conditions of long-term exposure to high voltage, enclosed environment, wind, sun and rain.

[0009] This project is mainly used on insulators of railway lines and trains. Its basic requirements include, but are not limited to: quick drying, excellent adhesion, long-lasting superhydrophobicity and self-cleaning properties. Of course, insulation and flame retardancy are also indispensable options.

[0010] The applicant's earlier application CN201911135161.0 disclosed an anti-corrosion and wear-resistant organosilicon coating and its preparation method, which clearly proposed to use hydroxyl silicone oil and dimethyl silicone oil as the main adhesives and methyl tributanone oxime silane and tetrabutanone oxime silane as crosslinking agents for combination.

[0011] The applicant's earlier application CN201911134306.5 discloses an organosilicon waterproof and aging-resistant material and its preparation method. It discloses reducing the amount of tetrabutylone oxime silane and introducing methyl tributanone oxime silane, which can avoid crystallization for a considerable period of time and shorten the surface drying time to 5 minutes.

[0012] In its previous research, the applicant has conducted relatively thorough studies on methyltributanone oxime silane and tetrabutanone oxime silane.

[0013] However, the above studies are all based on the presence of a catalyst. The catalyst itself can promote the cross-linking reaction inside the main adhesive and exhibit good fast-drying performance.

[0014] However, for coatings with flashover voltages exceeding 200%, organotin catalysts are generally avoided. While these catalysts may accelerate the crosslinking reaction, they do not contribute to improving flashover voltage resistance. In some experimental verifications, especially in the presence of fillers such as flame retardant powder, silica, and calcium carbonate, achieving a stable and reliable coating to improve flashover voltage resistance is not easy.

[0015] Therefore, the main technical problem to be solved in this case is: how to improve the fast-drying performance and anti-flashover voltage capability of silicone coatings while ensuring adhesion, hydrophobicity, and self-cleaning properties. Summary of the Invention

[0016] In view of the shortcomings of the prior art, the first objective of the present invention is to provide an organosilicon coating that has excellent fast drying performance and anti-flashover ability, excellent adhesion and bonding strength, and can maintain superhydrophobicity and self-cleaning properties for a long time.

[0017] A second objective of this invention is to provide a method for preparing the aforementioned organosilicon coating.

[0018] To achieve the first objective, the present invention adopts the following technical solution:

[0019] An organosilicon coating is composed of the following components in parts by weight:

[0020] 100 parts of α,ω-dihydroxypolysiloxane;

[0021] 2-8 parts of polydimethylsiloxane;

[0022] 2-6 parts titanium dioxide;

[0023] 30-60 parts flame retardant powder;

[0024] 10-20 parts of fumed silica;

[0025] 10-30 parts of nano-calcium carbonate;

[0026] 1-6 parts of antistatic agent;

[0027] 15-30 parts of fluorinated silicone resin;

[0028] 2-6 parts of silane coupling agent;

[0029] Crosslinking agent 0.2-0.5 parts;

[0030] 20-30 parts diluent;

[0031] The crosslinking agent is composed of tetrabutylone oxime silane and methyltributanone oxime silane in a weight ratio of 3-5:1.

[0032] In the aforementioned organosilicon coating, the viscosity of the α,ω-dihydroxy polysiloxane is 2000 mPa·s to 10000 mPa·s; and the viscosity of the polydimethylsiloxane is 50 cs to 1000 cs.

[0033] In the aforementioned organosilicon coating, the fluorinated silicone resin is polymethylnonafluorohexylsiloxane.

[0034] In the aforementioned organosilicon coating, the flame retardant powder is one or more of aluminum hypophosphite, ammonium polyphosphate, and α-calcined alumina; the antistatic agent is one of stearamide propyl hydroxyethyl quaternary ammonium nitrate, alkyl dicarboxymethyl ammonium acetate, and dodecyl dimethyl quaternary acetate.

[0035] In the aforementioned organosilicon coatings, the silane coupling agent is methacryloyloxypropyltrimethoxysilane and / or aminoethylaminopropyltriethoxysilane.

[0036] In the above-mentioned silicone coating, the diluent is one or more of solvent oils No. 120, No. 150, and No. 200.

[0037] Meanwhile, this invention also discloses a method for preparing the organosilicon coating as described in any of the above, comprising the following steps:

[0038] (1) Dehydrate each raw material to a moisture content of less than 0.3 wt%;

[0039] (2) Add α,ω-dihydroxypolysiloxane, polydimethylsiloxane, fluorinated silicone resin, titanium dioxide, flame retardant powder, fumed silica and nano calcium carbonate into a planetary tank, stir and heat to 115-125℃, and vacuum for 2 hours to obtain a homogeneous mixture.

[0040] (3) Grind the resulting mixture to a particle size ≤40μm;

[0041] (4) Add antistatic agent, silane coupling agent, crosslinking agent and diluent to the ground mixture, vacuum, stir for 1 hour, and then discharge and package.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The main improvement of this invention is that a more suitable crosslinking agent and silane coupling agent are selected for the main adhesive to achieve a better fast drying effect. The adhesion is improved by selecting low-viscosity polydimethylsiloxane and α,ω-dihydroxy polysiloxane, and the self-cleaning performance of the coating is improved by adding fluorinated silicone resin.

[0044] In this invention, a large amount of filler is added in order to achieve better anti-flashover voltage capability. However, a large amount of filler leads to a decrease in coating stability. To solve this problem, this invention reduces the amount of methyl tributanone oxime silane and appropriately extends the fast drying time. By combining and selecting crosslinking agents and coupling agents, the advantages of good fast drying effect, excellent coating stability, and strong adhesion are achieved. Detailed Implementation

[0045] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0046] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0047] Examples 1-5

[0048] A method for preparing an organosilicon coating includes the following steps:

[0049] (1) Dehydrate each raw material to a moisture content of less than 0.3 wt%;

[0050] (2) Add α,ω-dihydroxypolysiloxane, polydimethylsiloxane, fluorinated silicone resin, titanium dioxide, flame retardant powder, fumed silica and nano calcium carbonate into a planetary tank, stir and heat to 115-125℃, and vacuum for 2 hours to obtain a homogeneous mixture.

[0051] (3) Grind the resulting mixture to a particle size ≤40μm;

[0052] (4) Add antistatic agent, silane coupling agent, crosslinking agent and diluent to the ground mixture, vacuum, stir for 1 hour, and then discharge and package.

[0053] The formulations for Examples 1-8 are shown in Table 1 below.

[0054] Table 1 Formula Table

[0055]

[0056] The viscosity of α,ω-dihydroxypolysiloxane is 5000 mPa·s;

[0057] The polydimethylsiloxane is Dow Corning PMX-350;

[0058] The flame retardant powder is: aluminum hypophosphite;

[0059] The antistatic agent is: alkyl dicarboxymethyl ammonium acetone;

[0060] The fluorinated silicone resin is: polymethylnonafluorohexylsiloxane 5000 mPa·s;

[0061] The silane coupling agent is: methacryloyloxypropyltrimethoxysilane

[0062] The diluent is No. 150 solvent oil.

[0063] Example 6

[0064] The preparation methods of Examples 1-5 are the same as those in Example 4;

[0065] The difference is that the silane coupling agent is aminoethylaminopropyltriethoxysilane; and the flame retardant powder is ammonium polyphosphate.

[0066] Example 7

[0067] The preparation methods of Examples 1-5 are the same as those in Example 4;

[0068] The difference is that the viscosity of α,ω-dihydroxy polysiloxane is 3000 mPa·s; and the polydimethylsiloxane is Dow Corning PMX-200.

[0069] Example 8

[0070] The preparation methods of Examples 1-5 are the same as those in Example 4;

[0071] The difference is that the silane coupling agents are methacryloyloxypropyltrimethoxysilane and aminoethylaminopropyltriethoxysilane, with a weight ratio of 2:1.

[0072] Example 9

[0073] The preparation methods of Examples 1-5 are the same as those in Example 4;

[0074] The difference is that the silane coupling agents are methacryloyloxypropyltrimethoxysilane and aminoethylaminopropyltriethoxysilane, with a weight ratio of 1:2.

[0075] Comparative Examples 1-5

[0076] The preparation methods of comparative examples 1-5 are as described in Table 2 below;

[0077] Table 2 Formula Table

[0078]

[0079] The materials used are the same as in Examples 1-5.

[0080] Comparative Example 6

[0081] The method is largely the same as in Example 4, except that methyltris(methylisobutyl ketone oxime)silane is used instead of methyltributyl ketone oxime silane.

[0082] Comparative Example 7

[0083] It is largely the same as Example 4, except that dimethyl dibutyl ketone oxime silane is used instead of methyl tributanone oxime silane.

[0084] Performance testing

[0085] The test includes 12 items: appearance, viscosity, volatile matter, density, shelf life, flowability, flame retardancy, Shore hardness, tensile strength, elongation at break, flashover voltage, and surface drying time. The relevant acceptance standards are shown in Table 3. Since the samples met the standards for viscosity, volatile matter, density, shelf life, and flowability, they are not listed separately in the table.

[0086] Table 3 Customer Performance Requirements

[0087] Serial Number project Technical indicators 1 Appearance The fluid should be fine and uniform, free of bubbles, crusts, and impurities. 2 Flame retardancy V0 3 Shore hardness / A ≤60 4 Tensile strength / MPa ≥0.4 5 Elongation at break / % ≥100％ 6 flashover voltage U1 / U2≥1.5 7 Surface drying time ≤30min

[0088] The detection results of Examples 1-9 and Comparative Examples 1-7 are shown in Table 4 below;

[0089] Table 4 Test Results

[0090]

[0091] Results analysis:

[0092] 1. As can be seen from Examples 3-5, with the increase of crosslinking agent, the hardness gradually increases, the elongation at break gradually decreases, and the flashover voltage gradually increases, indicating that the higher the degree of crosslinking of the film layer, the greater the improvement in anti-flashover ability;

[0093] 2. As can be seen from the comparison of Examples 4, 8 and 9, when the silane coupling agent is methacryloyloxypropyltrimethoxysilane and aminoethylaminopropyltriethoxysilane with a weight ratio of 1:2, its overall tensile elongation, surface drying time and anti-flashover ability are better.

[0094] 3. As can be seen from Example 4 and Comparative Examples 1-4, as the concentration of methyl tributanone oxime silane increases, the surface drying time becomes shorter, but the overall anti-flashover capability cannot exceed 2. This indicates that methyl tributanone oxime silane can improve the fast drying speed. In other words, a trade-off must be made between fast drying speed and anti-flashover capability. Since the surface drying requirements of the insulator itself are not stringent during construction, the formulation of the present invention is suitable.

[0095] 4. As can be seen from Comparative Example 5, the amount of polydimethylsiloxane used should not be too much, otherwise the surface drying time and elongation at break will be affected; as can be seen from Comparative Examples 6 and 7, the use of other crosslinking agents is not superior to the present invention.

Claims

1. A macromolecular nano-insulating self-cleaning material, characterized in that, consists of the following components by weight: α, ω-dihydroxypolydimethylsiloxane 100 parts; polydimethylsiloxane 2-8 parts; titanium white 2-6 parts; flame-retardant powder 30-60 parts; fumed silica 10-20 parts; nano calcium carbonate 10-30 parts; antistatic agent 1-6 parts; fluorine-containing silicone resin 15-30 parts; silane coupling agent 2-6 parts; crosslinking agent 0.2-0.5 parts; diluent 20-30 parts; The weight ratio of the crosslinking agents tetrabutyl ketoxime silane and methyltributyl ketoxime silane is 3-5:1; The silane coupling agent is methacryloyloxypropyl trimethoxysilane and aminoethyl aminopropyl triethoxysilane, and the mass ratio of methacryloyloxypropyl trimethoxysilane and aminoethyl aminopropyl triethoxysilane is 1:

2.

2. The polymeric nanoinsulating self-cleaning material according to claim 1, wherein The viscosity of the α, ω-dihydroxypolydimethylsiloxane is 2000 mPa.s-10000 mPa.s; the viscosity of the polydimethylsiloxane is 50 cs-1000 cs.

3. The polymeric nanoinsulating self-cleaning material according to claim 1, wherein The fluorine-containing silicone resin is polymethyl nonafluorohexyl siloxane.

4. The polymeric nanoinsulating self-cleaning material according to claim 1, wherein The flame-retardant powder is one or more of aluminum hypophosphite, ammonium polyphosphate, and α-type calcined alumina; the antistatic agent is one of stearoyl amido propyl hydroxyethyl quaternary amine nitrate, alkyl dicarboxymethyl ammonium lactone, and dodecyl dimethyl quaternary ethyl lactone.

5. The polymeric nanoinsulating self-cleaning material according to claim 1, wherein The diluent is one or more of No. 120, No. 150, and No. 200 solvent oil.

6. The method for preparing the polymer nanometer insulating self-cleaning material according to any one of claims 1-5, characterized in that, It includes the following steps: (1) Dehydrate each raw material to a water content of 0.3 wt% or less; (2) Put the α, ω-dihydroxypolydimethylsiloxane, polydimethylsiloxane, fluorine-containing silicone resin, titanium white, flame-retardant powder, fumed silica, and nano calcium carbonate into a planetary barrel, stir and heat to 115-125°C, vacuum for 2h, and obtain a uniform mixture; (3) Grind the obtained mixture to a particle size of ≤40μm; (4) Add the antistatic agent, silane coupling agent, crosslinking agent, and diluent to the ground mixture, vacuum, stir for 1h, and discharge and package.

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