Single-component organic silicon insulating impregnating varnish and preparation method thereof

Abstract

The invention relates to a single-component organic silicon insulating impregnating varnish and a preparation method thereof, the single-component organic silicon insulating impregnating varnish comprises phenyl silicone resin with vinyl groups on a T chain link and an M chain link and a hydrogen-containing group on a D chain link, a platinum catalyst and an inhibitor, and water, xylene and a cosolvent are added, mixed, stirred and heated; uniformly mixing a trifunctional monomer and a difunctional monomer, dropwise adding the mixture into the reaction kettle, and carrying out heat preservation reaction; adding a monofunctional monomer for reaction, separating liquid, washing with a saturated sodium bicarbonate aqueous solution, washing with pure water, and taking an organic phase; removing the solvent in vacuum to obtain phenyl silicone resin; and adding a platinum catalyst and an inhibitor, and uniformly mixing. By controlling the position of the hydrogen-containing group on the D chain link and controlling the resin to form a nonlinear topological structure through the raw material ratio, the activity of the hydrogen-containing group is reduced, the stability of the hydrogen-containing group is improved, and the curing speed of the resin at different temperatures is controlled through the activity differentiation design of the reaction functional groups, so that the curing performance of the resin is improved. And the requirement of two-stage curing is met.

Description

Technical Field

[0001] This invention relates to a single-component organosilicon insulating impregnating varnish and its preparation method, belonging to the field of impregnating varnish synthesis technology. Background Technology

[0002] Impregnating varnishes are commonly used for insulation of electronic and electrical components, impregnation of H-class motor and transformer coils, impregnation for motor bushings, electrical insulation windings, and main insulation of high-voltage motors. Based on their main components, they can be classified into epoxy, polyester, and silicone types. In terms of heat resistance, polyester impregnating varnishes have a heat resistance rating of B (130℃) or F (155℃), but they soften easily at high temperatures and decompose with long-term use. Epoxy impregnating varnishes have better heat resistance than polyester, reaching F (155℃) or H (180℃). Silicone impregnating varnishes have the best heat resistance, reaching H (180℃) or C (above 200℃), with short-term temperature resistance up to 300℃. From the perspective of mechanical properties and adhesion, polyester impregnation varnishes have low film hardness and poor impact resistance, making them prone to cracking due to vibration. Epoxy impregnation varnishes, with their high cross-linking density, possess excellent mechanical strength (Shore D 85 and above) and adhesion, but are brittle and easily cracked by thermal shock. Silicone impregnation varnishes exhibit good flexibility (elongation 500%~1000%). From the perspective of chemical corrosion resistance, polyester impregnation varnishes are sensitive to acids, alkalis, and organic solvents, and are prone to swelling or degradation. Epoxy and silicone impregnation varnishes demonstrate excellent chemical corrosion resistance. From the perspective of environmental friendliness and process adaptability, traditional solvent-based polyester impregnation varnishes have high VOCs, and solvent-free / water-based processes are still immature. Epoxy impregnation varnishes are mainly solvent-free, but have a short shelf life. Silicone impregnation varnishes are environmentally friendly and have good storage resistance. In summary, silicone impregnation varnishes have superior heat resistance, environmental friendliness, and process stability, making them particularly suitable for applications such as new energy vehicle motors and rail transit traction systems.

[0003] Patent No. 202411137201.6 discloses a C-grade solvent-free organosilicon impregnation varnish and its preparation method. This patent uses vinyl methyl phenyl silicone resin and hydrogen-containing methyl phenyl silicone resin as the main components of the impregnation varnish. By adjusting the molar ratio between each structural unit, the viscosity of the resin is kept within a suitable range. However, its reactive groups are all at the end groups, resulting in high reactivity, short gel time, and need to be used up in a short time after mixing. It also has poor storage stability. In addition, since it is a two-component varnish, the construction process is relatively complicated. Patent 202410640102.3 discloses a single-component solvent-free organosilicon impregnation varnish with long shelf life and fast curing, and its preparation method. It mainly includes a polymethylphenyl vinylhydrosiloxane resin with vinyl and hydrogen groups at the ends, and a thermosensitive platinum catalyst that is stable below the critical temperature but can promote the addition reaction of polymethylphenyl vinylhydrosiloxane resin above the critical temperature. The core of the invention lies in the preparation of a special thermosensitive catalyst. The resin storage stability is not improved through resin design. At the same time, due to the characteristics of the thermosensitive catalyst, the curing temperature and curing time are fixed, which is not suitable for the segmented curing vacuum pressure impregnation process. Moreover, the catalyst synthesis process is complicated and costly. Summary of the Invention

[0004] To address the problems of poor storage stability, poor process adaptability, and high cost of impregnating varnishes, this invention provides a single-component organosilicon insulating impregnating varnish and its preparation method.

[0005] The technical solution of this invention is as follows: A one-component silicone insulating impregnating varnish comprises a phenyl silicone resin having vinyl groups on T- and M-units and hydrogen-containing groups on D-units, a platinum catalyst, and an inhibitor. The phenyl silicone resin has the molecular formula (ViSiO). 3 / 2 )x(PhSiO 3 / 2 )y(MeSiO 3 / 2 )z(HMeSiO 2 / 2 )m(PhMeSiO 2 / 2 )n(Me3SiO)a(ViMe2SiO)b, (x+y+z): (m+n): (a+b)=(1.2-2.2):1: (0.7-1.4), (x+b): m=0.85-0.95; The platinum catalyst is a platinum-divinyltetramethyldisiloxane complex, used at 15-25 ppm of the total mass of the system, and the inhibitor is ethynylcyclohexanol, used at 0.05-0.15% of the total mass of the system.

[0006] Preferably, the amount of platinum catalyst is 20 ppm of the total mass of the system, the amount of inhibitor is 0.1% of the total mass of the system, and x / b ≥ 1.5.

[0007] The method for preparing the single-component organosilicon insulating impregnating varnish includes the following steps: (1) Add water, xylene and co-solvent to the reactor and mix and stir, then heat up; mix the trifunctional and difunctional monomers evenly and add them dropwise to the reactor, keep the temperature and react for 2-3 hours; add the monofunctional monomer to the reactor; (2) After the reaction is complete, let it stand, separate the liquid and wash it once with saturated sodium bicarbonate aqueous solution, then wash it twice with pure water, and separate the liquid to take the organic phase; (3) The solvent was removed from the organic phase under vacuum to obtain phenyl silicone resin; (4) Mix phenyl silicone resin, platinum catalyst and inhibitor evenly to obtain a single-component organosilicon insulating impregnation varnish.

[0008] Preferably, the trifunctional monomer in step (1) is one or more of vinyl monomers, phenyl monomers and methyl monomers, the vinyl monomer is one of vinyltriethoxysilane and vinyltrimethoxysilane, the phenyl monomer is one of phenyltriethoxysilane and phenyltrimethoxysilane, and the methyl monomer is one of methyltriethoxysilane and methyltrimethoxysilane. The difunctional monomer is one or more of methylphenyldimethoxysilane, methylphenyldiethoxysilane, and methyldichlorosilane, and must contain methyldichlorosilane.

[0009] More preferably, the amount of water used in step (1) is 1.2-1.8 times the total mass of the trifunctional and difunctional monomers; The amount of xylene used is 60-90% of the total mass of the trifunctional and difunctional monomers.

[0010] Preferably, the co-solvent in step (1) is one or a mixture of several lower fatty alcohols.

[0011] More preferably, the co-solvent is methanol, ethanol, isopropanol or a mixture thereof, and the amount of co-solvent used is 5-15% of the total mass of the trifunctional and difunctional monomers.

[0012] Preferably, the monofunctional monomer in step (1) is one or more of dimethylvinylethoxysilane, dimethylvinylchlorosilane, trimethylethoxysilane, and trimethylchlorosilane.

[0013] Preferably, the amount of sodium bicarbonate saturated solution used in step (2) is 15% of the total mass of the system in step (1), and the amount of pure water used each time is 15% of the total mass of the system in step (1).

[0014] Preferably, in step (1), the mixture is stirred for 5-15 minutes, and then heated to 60-75°C; the trifunctional and difunctional monomers are mixed evenly and added dropwise to the reactor, with the addition time controlled at 20-30 minutes, and the reaction is kept at the temperature for 2-3 hours; the monofunctional monomer is added to the reactor and the reaction is carried out for 2-4 hours.

[0015] Step (3) Remove the solvent from the organic phase under vacuum at 70-90℃.

[0016] The beneficial effects of this invention are: 1. Based on the hydrogen-containing groups located in the D-unit, a three-dimensional nonlinear topological structure is formed by controlling the ratio of M, D, and T monomers and the synthesis process. This structure has several advantages: First, it has a high functional group density, allowing for more reaction sites, resulting in high crosslinking density after curing, excellent mechanical properties, higher chemical resistance, and lower heat loss. Second, the T, D, and M units in this topological structure have a specific positional relationship, resulting in low reactivity of the vinyl groups in the T-unit and high reactivity of the vinyl groups in the M-unit. Furthermore, by controlling the methyl and phenyl groups on each unit, steric hindrance is altered, further regulating the reactivity of the groups and creating a differentiated design of reactive group activity. Third, by controlling the proportion of vinyl groups in the M-unit and the proportion of methyl and phenyl groups on each unit, a gradient of silicone resin group activity is created, controlling the resin's curing activity and curing rate at different temperatures. This results in minimal viscosity increase during the impregnation step and rapid curing during the curing stage, meeting the requirements of two-stage curing while also considering post-curing performance.

[0017] 2. By controlling the position of the hydrogen-containing groups on the D-units, the activity of the hydrogen-containing groups is reduced. Simultaneously, due to the topological structure of silicone resin, the hydrogen-containing groups are not exposed, reducing contact between themselves and with vinyl groups, thus improving the stability of the hydrogen-containing groups. This enhances the retention rate of hydrogen-containing groups during resin preparation and the storage stability of the silicone resin. Furthermore, the reduced chain entanglement in the silicone resin's topology results in higher flowability and processability. Detailed Implementation

[0018] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0019] To better understand this invention, the following embodiments and comparative examples further illustrate its content, but the scope of this invention is not limited to the embodiments described below. The parts in the embodiments and comparative examples refer to parts by mass.

[0020] Example 1 (1) Add water, xylene and ethanol to the reaction vessel and mix and stir for 10 min, then heat to 65℃; mix 89 parts vinyltrimethoxysilane, 178.5 parts phenyltrimethoxysilane, 115 parts methyldichlorosilane and 45.6 parts methylphenyldimethoxysilane evenly, and add dropwise to the reaction vessel, controlling the dropwise addition time to 20 min, and keep the temperature for 2 h; add 82.8 parts trimethylethoxysilane and 32.6 parts dimethylvinylethoxysilane to the reaction vessel and react for 4 h.

[0021] (2) After the reaction is complete, let it stand, separate the liquid and wash it once with saturated sodium bicarbonate aqueous solution, then wash it twice with pure water, and separate the liquid to take the organic phase.

[0022] (3) The organic phase was desolventized under vacuum at 70°C to obtain phenyl silicone resin.

[0023] (4) Mix the phenyl silicone resin, platinum catalyst and inhibitor evenly.

[0024] Example 2 (1) Add water, xylene and methanol to the reaction vessel and stir for 10 min, then heat to 60℃; mix 180.8 parts of vinyltriethoxysilane, 300.5 parts of phenyltriethoxysilane and 115 parts of methyldichlorosilane evenly, and add them dropwise to the reaction vessel. The dropwise addition time is controlled at 25 min, and the reaction is kept at the temperature for 2.5 h; add 76 parts of trimethylchlorosilane to the reaction vessel and react for 3.5 h.

[0025] (2) After the reaction is complete, let it stand, separate the liquid and wash it once with saturated sodium bicarbonate aqueous solution, then wash it twice with pure water, and separate the liquid to take the organic phase.

[0026] (3) The organic phase was desolventized under vacuum at 80°C to obtain phenyl silicone resin.

[0027] (4) Mix the phenyl silicone resin, platinum catalyst and inhibitor evenly.

[0028] Example 3 (1) Add water, xylene and isopropanol to the reaction vessel and mix and stir for 10 min, then heat to 70℃; mix 102.8 parts of vinyltriethoxysilane, 238 parts of phenyltrimethoxysilane, 82 parts of methyltriethoxysilane and 115 parts of methyldichlorosilane evenly, add dropwise to the reaction vessel, control the dropwise addition time to 30 min, and keep the temperature for 3 h; add 71 parts of trimethylethoxysilane and 46.9 parts of dimethylvinylethoxysilane to the reaction vessel and react for 3 h.

[0029] (2) After the reaction is complete, let it stand, separate the liquid and wash it once with saturated sodium bicarbonate aqueous solution, then wash it twice with pure water, and separate the liquid to take the organic phase.

[0030] (3) The organic phase is desolventized under vacuum at 90°C to obtain phenyl silicone resin.

[0031] (4) Mix the phenyl silicone resin, platinum catalyst and inhibitor evenly.

[0032] Example 4 (1) Add water, xylene and ethanol to the reaction vessel and stir for 10 min, then heat to 75℃; mix 118.6 parts vinyltrimethoxysilane, 238 parts phenyltrimethoxysilane, 35.7 parts methyltriethoxysilane and 115 parts methyldichlorosilane evenly, add dropwise to the reaction vessel, control the dropwise addition time at 25 min, and keep the temperature for 2.5 h; add 153 parts trimethylethoxysilane and 11.6 parts dimethylvinylmethoxysilane to the reaction vessel and react for 2.5 h.

[0033] (2) After the reaction is complete, let it stand, separate the liquid and wash it once with saturated sodium bicarbonate aqueous solution, then wash it twice with pure water, and separate the liquid to take the organic phase.

[0034] (3) The organic phase was desolventized under vacuum at 80°C to obtain phenyl silicone resin.

[0035] (4) Mix the phenyl silicone resin, platinum catalyst and inhibitor evenly.

[0036] Example 5 (1) Add water, xylene and ethanol to the reaction vessel and mix and stir for 10 min, then heat to 75℃; mix 133.2 parts vinyltriethoxysilane, 144.2 parts phenyltriethoxysilane, 150 parts methyltrimethoxysilane, 115 parts methyldichlorosilane and 109.4 parts methylphenyldimethoxysilane evenly, add dropwise to the reaction vessel, control the dropwise addition time at 25 min, and keep the temperature for 3 h; add 165.6 parts trimethylethoxysilane and 24.1 parts dimethylvinylchlorosilane to the reaction vessel and react for 2 h.

[0037] (2) After the reaction is complete, let it stand, separate the liquid and wash it once with saturated sodium bicarbonate aqueous solution, then wash it twice with pure water, and separate the liquid to take the organic phase.

[0038] (3) The organic phase was desolventized under vacuum at 80°C to obtain phenyl silicone resin.

[0039] (4) Mix the phenyl silicone resin, platinum catalyst and inhibitor evenly.

[0040] Example 6 (1) Add water, xylene and ethanol to the reaction vessel and stir for 10 min, then heat to 75℃; mix 89 parts vinyltrimethoxysilane, 178.5 parts phenyltrimethoxysilane, 160.5 parts methyltriethoxysilane, 115 parts methyldichlorosilane and 63.1 parts methylphenyldiethoxysilane evenly, add dropwise to the reaction vessel, control the dropwise addition time at 25 min, and keep the temperature for 2.5 h; add 125.1 parts trimethylmethoxysilane and 39 parts dimethylvinylethoxysilane to the reaction vessel and react for 2.5 h.

[0041] (2) After the reaction is complete, let it stand, separate the liquid and wash it once with saturated sodium bicarbonate aqueous solution, then wash it twice with pure water, and separate the liquid to take the organic phase.

[0042] (3) The organic phase was desolventized under vacuum at 80°C to obtain phenyl silicone resin.

[0043] (4) Mix the phenyl silicone resin, platinum catalyst and inhibitor evenly.

[0044] Comparative Example 1 (1) Add water, xylene and ethanol to the reaction vessel and mix and stir for 10 min, then heat to 75℃; mix 89 parts vinyltrimethoxysilane, 178.5 parts phenyltrimethoxysilane, 160.5 parts methyltriethoxysilane, 129 parts dimethyldichlorosilane and 63.1 parts methylphenyldiethoxysilane evenly, add dropwise to the reaction vessel, control the dropwise addition time at 25 min, and keep the temperature for 2.5 h; add 90 parts dimethylmethoxysilane, 20.9 parts trimethylmethoxysilane and 39 parts dimethylvinylethoxysilane to the reaction vessel and react for 2.5 h.

[0045] (2) After the reaction is complete, let it stand, separate the liquid and wash it once with saturated sodium bicarbonate aqueous solution, then wash it twice with pure water, and separate the liquid to take the organic phase.

[0046] (3) The organic phase was desolventized under vacuum at 80°C to obtain phenyl silicone resin.

[0047] (4) Mix the phenyl silicone resin, platinum catalyst and inhibitor evenly.

[0048] Comparative Example 2 (1) Add water, xylene and ethanol to the reaction vessel and mix and stir for 10 min, then heat to 75℃; mix 133.2 parts vinyltriethoxysilane, 144.2 parts phenyltriethoxysilane, 13.6 parts methyltrimethoxysilane, 135.5 parts trichlorosilane, 120.2 parts dimethyldimethoxysilane and 109.4 parts methylphenyldimethoxysilane evenly, add dropwise to the reaction vessel, control the dropwise addition time at 25 min, and keep the temperature for 3 h; add 165.6 parts trimethylethoxysilane and 24.1 parts dimethylvinylchlorosilane to the reaction vessel and react for 2 h.

[0049] (2) After the reaction is complete, let it stand, separate the liquid and wash it once with saturated sodium bicarbonate aqueous solution, then wash it twice with pure water, and separate the liquid to take the organic phase.

[0050] (3) The organic phase was desolventized under vacuum at 80°C to obtain phenyl silicone resin.

[0051] (4) Mix the phenyl silicone resin, platinum catalyst and inhibitor evenly.

[0052] Comparative Example 3 (1) Add water, xylene and ethanol to the reaction vessel and stir for 10 min, then heat to 75℃; mix 118.6 parts vinyltrimethoxysilane, 238 parts phenyltrimethoxysilane, 27.1 parts trichlorosilane, 57.5 parts methyldichlorosilane and 64.5 parts dimethyldichlorosilane evenly, add dropwise to the reaction vessel, control the dropwise addition time to 25 min, and keep the temperature for 2.5 h; add 118.3 parts trimethylethoxysilane, 27 parts dimethylmethoxysilane and 11.6 parts dimethylvinylmethoxysilane to the reaction vessel and react for 2.5 h.

[0053] (2) After the reaction is complete, let it stand, separate the liquid and wash it once with saturated sodium bicarbonate aqueous solution, then wash it twice with pure water, and separate the liquid to take the organic phase.

[0054] (3) The organic phase was desolventized under vacuum at 80°C to obtain phenyl silicone resin.

[0055] (4) Mix the phenyl silicone resin, platinum catalyst and inhibitor evenly.

[0056] Comparative Example 4 (1) Add water, xylene and isopropanol to the reactor and mix and stir for 10 min, then heat to 70℃; mix 102.8 parts vinyltriethoxysilane, 238 parts phenyltrimethoxysilane, 160.5 parts methyltriethoxysilane and 115 parts methyldichlorosilane evenly, add dropwise to the reactor, control the dropwise addition time to 30 min, and keep the temperature for 3 h; add 71 parts trimethylethoxysilane and 46.9 parts dimethylvinylethoxysilane to the reactor and react for 3 h.

[0057] (2) After the reaction is complete, let it stand, separate the liquid and wash it once with saturated sodium bicarbonate aqueous solution, then wash it twice with pure water, and separate the liquid to take the organic phase.

[0058] (3) The organic phase is desolventized under vacuum at 90°C to obtain phenyl silicone resin.

[0059] (4) Mix the phenyl silicone resin, platinum catalyst and inhibitor evenly.

[0060] Comparative Example 5 (1) Add water, xylene and isopropanol to the reactor and mix and stir for 10 min, then heat to 70℃; mix 38 parts vinyltriethoxysilane, 238 parts phenyltrimethoxysilane, 178.3 parts methyltriethoxysilane and 115 parts methyldichlorosilane evenly, add dropwise to the reactor, control the dropwise addition time to 30 min, and keep the temperature for 3 h; add 30.8 parts trimethylethoxysilane and 91.2 parts dimethylvinylethoxysilane to the reactor and react for 3 h.

[0061] (2) After the reaction is complete, let it stand, separate the liquid and wash it once with saturated sodium bicarbonate aqueous solution, then wash it twice with pure water, and separate the liquid to take the organic phase.

[0062] (3) The organic phase is desolventized under vacuum at 90°C to obtain phenyl silicone resin.

[0063] (4) Mix the phenyl silicone resin, platinum catalyst and inhibitor evenly.

[0064] Example 7 Examples 1-6 and Comparative Examples 1-5 were tested, and the results are shown in Table 1 below.

[0065] Table 1

[0066] As shown in the table above, the viscosity of the products in Examples 1-6 is <1400 mPa·s, which meets the requirements for impregnation coating. By keeping all hydrogen-containing groups located in the D-unit and adjusting the position of the vinyl groups, the stability in open containers is excellent, and the viscosity increase is less than 3 times. This meets the requirements of the impregnation process, which requires the temperature of the parts and the insulating varnish to be 60℃±5℃, the vacuum degree to be 18~25 Pa for 4 h, and the vacuum degree to be 0.45~0.55 MPa for 1.5 h. The curing time at 150℃ is short, and the curing time of the second stage after impregnation is short, which reduces energy consumption and meets the requirements of the two-stage curing impregnation process. Comparative Examples 1-3 showed that the positions of hydrogen-containing groups were changed to the M, T, and MDT positions, respectively. The products were prone to gelation in open containers at 50°C, which did not meet the requirements for dip coating. In Comparative Example 4, (x+y+z):(m+n):>2.2, the product could not form a specific topological structure, had a lot of intermolecular entanglement, high viscosity, and poor impregnation effect. In Comparative Example 5, x / b<1.5, the product showed a large increase in viscosity in open containers at 50°C, which did not meet the requirements for impregnation.

[0067] The thermal weight loss of silicone resin is closely related to its cross-linking structure, the type and content of organic groups. In particular, the introduction of phenyl groups can significantly improve thermal stability and reduce thermal weight loss. As shown in the table above, Examples 1 and 2 have high phenyl content and low thermal weight loss, while Examples 5 and Comparative Example 2 have low phenyl content and high thermal weight loss. Examples 1-6, due to their high degree of resin cross-linking and the introduction of phenyl groups, show a thermal weight loss of <5% at 400℃, indicating good thermal stability.

[0068] The storage stability of single-component impregnation varnish is crucial. By allowing the resin to stand at room temperature in a sealed container, the viscosity of the resin before and after standing was tested. As shown in the table above, the viscosity of Examples 1-6 fluctuated slightly, with an increase of less than 5%, which provides convenience for downstream storage and application.

[0069] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The embodiments and features described in these embodiments can be arbitrarily combined without conflict. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A single-component organosilicon insulating impregnating varnish, characterized in that: The single-component organosilicon insulating impregnating varnish comprises a phenyl silicone resin having vinyl groups on the T and M links and hydrogen-containing groups on the D link, a platinum catalyst, and an inhibitor. The phenyl silicone resin has the molecular formula (ViSiO). 3 / 2 )x(PhSiO 3 / 2 )y(MeSiO 3 / 2 )z(HMeSiO 2 / 2 )m(PhMeSiO 2 / 2 )n(Me3SiO)a(ViMe2SiO)b, (x+y+z): (m+n): (a+b)=(1.2-2.2):1: (0.7-1.4), (x+b): m=0.85-0.95; The platinum catalyst is a platinum-divinyltetramethyldisiloxane complex, used at 15-25 ppm of the total mass of the system, and the inhibitor is ethynylcyclohexanol, used at 0.05-0.15% of the total mass of the system.

2. The single-component organosilicon insulating impregnating varnish according to claim 1, characterized in that: The amount of platinum catalyst used is 20 ppm of the total mass of the system, the amount of inhibitor used is 0.1% of the total mass of the system, and x / b ≥ 1.

5.

3. The method for preparing the single-component organosilicon insulating impregnating varnish according to any one of claims 1-2, characterized in that, The preparation method includes the following steps: (1) Add water, xylene and co-solvent to the reactor and mix and stir, then heat up; mix the trifunctional and difunctional monomers evenly and add them dropwise to the reactor, keep the temperature and react for 2-3 hours; add the monofunctional monomer to the reactor; (2) After the reaction is complete, let it stand, separate the liquid and wash it once with saturated sodium bicarbonate aqueous solution, then wash it twice with pure water, and separate the liquid to take the organic phase; (3) The solvent was removed from the organic phase under vacuum to obtain phenyl silicone resin; (4) Mix phenyl silicone resin, platinum catalyst and inhibitor evenly to obtain a single-component organosilicon insulating impregnation varnish.

4. The method for preparing the single-component organosilicon insulating impregnating varnish as described in claim 3, characterized in that, The trifunctional monomer in step (1) is one or more of vinyl monomers, phenyl monomers and methyl monomers. The vinyl monomer is one of vinyltriethoxysilane and vinyltrimethoxysilane. The phenyl monomer is one of phenyltriethoxysilane and phenyltrimethoxysilane. The methyl monomer is one of methyltriethoxysilane and methyltrimethoxysilane. The difunctional monomer is one or more of methylphenyldimethoxysilane, methylphenyldiethoxysilane, and methyldichlorosilane, and must contain methyldichlorosilane.

5. The method for preparing the single-component organosilicon insulating impregnating varnish as described in claim 4, characterized in that, In step (1), the amount of water used is 1.2-1.8 times the total mass of the trifunctional and difunctional monomers; The amount of xylene used is 60-90% of the total mass of the trifunctional and difunctional monomers.

6. The method for preparing the single-component organosilicon insulating impregnating varnish as described in claim 3, characterized in that, The cosolvent in step (1) is one or a mixture of several lower fatty alcohols.

7. The method for preparing the single-component organosilicon insulating impregnating varnish as described in claim 6, characterized in that, The co-solvent is methanol, ethanol, isopropanol or a mixture thereof, and the amount of co-solvent used is 5-15% of the total mass of the trifunctional and difunctional monomers.

8. The solvent-free, single-component organosilicon insulating impregnating varnish and its preparation method as described in claim 3, characterized in that, The monofunctional monomer in step (1) is one or more of dimethylvinylethoxysilane, dimethylvinylchlorosilane, trimethylethoxysilane, and trimethylchlorosilane.

9. The solvent-free, single-component organosilicon insulating impregnating varnish and its preparation method as described in claim 3, characterized in that, The amount of sodium bicarbonate saturated solution used in step (2) is 15% of the total mass of the system in step (1), and the amount of pure water used each time is 15% of the total mass of the system in step (1).

10. The solvent-free, single-component organosilicon insulating impregnating varnish and its preparation method as described in claim 3, characterized in that, Step (1) Mix and stir for 5-15 minutes, then heat to 60-75℃; mix the trifunctional and difunctional monomers evenly and add them dropwise to the reactor, controlling the dropwise addition time at 20-30 minutes, and keep the temperature for 2-3 hours; add the monofunctional monomer to the reactor and react for 2-4 hours. Step (3) Remove the solvent from the organic phase under vacuum at 70-90℃.

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