A surface protection method for epoxy resin

Abstract

This invention discloses a surface protection method for epoxy resin, relating to the field of coating technology. The surface protection method for epoxy resin provided by this invention involves first plasma-activating the epoxy resin matrix, then grafting it into an alkoxyfluorosilane vapor atmosphere, and finally coating the epoxy resin matrix surface with a silane gel containing alkoxysilanes. This forms a dense, low-porosity protective layer, effectively blocking water vapor, ions, and small molecules. While further hindering carrier accumulation, the surface defects of the protective layer are also reduced. Furthermore, the protective layer has lower surface energy, stronger hydrophobicity, and higher insulation, which can inhibit the accumulation and migration of carriers on the epoxy resin matrix and the protective layer surface. Based on the combined effect of the above mechanisms, this invention can significantly reduce the surface flashover initiation voltage of the epoxy resin matrix and inhibit the carbonization of the epoxy resin.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and more specifically, to a surface protection method for epoxy resin. Background Technology

[0002] Epoxy resins are widely used in electrical equipment insulation due to their excellent electrical insulation, mechanical strength, and bonding properties. In recent years, with the rapid development of industries such as new energy and consumer electronics, epoxy resin materials have faced the challenge of operating under extreme conditions such as high voltage and high temperature. Under these extreme conditions, adsorbed water films and shallow energy level traps easily form on the epoxy resin surface, increasing the probability of surface flashover. This leads to repeated discharges and thermal decomposition and carbonization reactions on the epoxy resin surface. The conductive carbides generated by surface flashover easily form conductive paths within the epoxy resin material, significantly affecting its volume resistivity, dielectric strength, and arc resistance, ultimately causing insulation failure. Researchers have proposed improvements to enhance the lifespan of epoxy resin insulation materials by suppressing carbon deposition and increasing the initial surface flashover voltage. However, existing improvement methods typically only address one aspect. Therefore, it is essential to provide a method that can simultaneously increase the surface flashover initiation voltage and reduce surface carbon deposition. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a method for surface protection with epoxy resin.

[0004] The above-mentioned objective of this invention is achieved through the following technical solution: A method for surface protection with epoxy resin includes the following steps: S1. Plasma activation is performed on the epoxy resin matrix to obtain a surface-activated matrix; S2. The surface-activated matrix obtained in step S1 is placed in an alkoxyfluorosilane vapor atmosphere for grafting to obtain a matrix with surface-grafted alkoxyfluorosilane. S3. Disperse silane containing alkoxy groups in a solvent to obtain silane sol, adjust the pH to <7 and age to obtain silane gel; coat the silane gel onto the surface of the substrate grafted with fluorosilane obtained in step S2, and after curing, obtain an epoxy resin with a protective layer on the surface; the solvent includes water.

[0005] The epoxy resin surface protection method provided by this invention first involves plasma activation of the epoxy resin matrix, which enriches the surface of the epoxy resin matrix with hydrophilic groups, enabling it to adsorb water molecules from the air. Subsequently, the epoxy resin matrix is ​​placed in an alkoxyfluorosilane vapor atmosphere. The alkoxy groups in the alkoxyfluorosilane readily hydrolyze to form silanol groups under the induction of active groups on the epoxy resin matrix surface and trace amounts of water. These silanol groups can then react and bond with the active groups formed by plasma activation on the matrix surface. Building upon this, in step S3, this invention further introduces silanes containing alkoxy groups. The newly introduced silane, along with the alkoxyfluorosilane introduced in step S2, the intrinsic active groups on the activated matrix surface, and water, can also bond through the hydrolysis of the alkoxy groups, allowing the alkoxy-containing silanes to tightly bond with the epoxy resin matrix. Therefore, this invention can form a tightly bonded protective layer on the surface of an epoxy resin matrix. The resulting protective layer, based on the introduction of alkoxy-containing fluorosilanes and alkoxy-containing silanes, possesses lower surface energy, stronger hydrophobicity, and higher insulation, suppressing carrier accumulation on the epoxy resin matrix and the protective layer surface, while also hindering carrier migration. Furthermore, the alkoxy-containing silanes, introduced in a gel form, form a dense, low-porosity coating, effectively blocking water vapor, ions, and small molecules. This further hinders carrier accumulation while reducing surface defects in the protective layer (surface defects also easily form shallow-level traps, making the coating prone to carrier capture). Based on the combined effect of these mechanisms, this invention can significantly reduce the surface flashover initiation voltage of the epoxy resin matrix. Simultaneously, the increased density reduces micropores within the coating, directly suppressing partial discharge and thermal corrosion caused by air gaps. High composite strength eliminates the interfacial air gap between the coating and the matrix, preventing surface breakdown caused by interfacial peeling under high field strength. Both effectively block the direct action of electric arc heat on epoxy resin, which can inhibit the carbon precipitation of organic chains from the source, thereby reducing the amount of carbon precipitation in epoxy resin.

[0006] It should be noted that this application requires grafting fluorosilane in step S2 and then introducing alkoxysilane in step S3 because the low surface energy inherent in fluorosilane can "passivate" defects on the substrate surface and has a certain rate-limiting effect on the reaction between the active sites on the substrate surface and the subsequently introduced alkoxysilane. This can prevent the disordered condensation of alkoxysilane on the uneven substrate surface, which would lead to a decrease in coating density and an increase in defects.

[0007] It should be noted that the method of introducing fluorosilanes in this application requires steam grafting. Although conventional coating methods such as spin coating can also graft alkoxyfluorosilanes onto the epoxy resin matrix, they can easily lead to excessively high grafting density of fluorosilanes on the matrix surface, affecting the subsequent grafting of alkoxysilanes. Furthermore, the introduction of alkoxysilanes in this application requires the preparation of a gel via a sol-gel method. The inventors of this application have found through experiments that if the silane sol is directly coated onto the matrix surface, subsequent curing, whether direct or aging followed by curing, cannot form a coating with a smooth surface, high density, and reduced porosity. This is presumably because the sol can form a more regular molecular arrangement structure after aging; therefore, aging to form a gel is a necessary condition for achieving the coating effect. However, if the sol is directly coated onto the matrix surface and then aged to form a gel, the alkoxysilane sol, under conditions containing more migratory water, will rapidly hydrolyze and condense with the active sites on the matrix surface. The reaction is difficult to control, and this will also result in a coating that cannot achieve a dense and smooth morphology.

[0008] It should be noted that the silane sol in this application needs to be aged under acidic conditions. Under neutral conditions, the hydrolysis rate of the silane sol is too slow, easily leading to the separation of the silane phase and the aqueous phase, making it impossible to form a homogeneous system. Under alkaline conditions, the silane sol tends to form particulate agglomerates, severely affecting the density and protective performance of the coating. Acidic conditions can catalyze the hydrolysis of the silane sol and form a linear polymer structure, which is beneficial for obtaining a dense, continuous coating with excellent adhesion.

[0009] Preferably, the plasma activation in step S1 satisfies at least one of the following (1)-(5): (1) The carrier gas for plasma activation in step S1 includes oxygen; (2) The plasma activation described in step S1 is carried out under a cavity pressure of 120-180 mTorr; (3) The plasma activation described in step S1 is carried out under the condition of a carrier gas flow rate of 80-120 sccm; (4) The plasma activation described in step S1 is carried out under a power of 60-100W; (5) The plasma activation time in step S1 is 30-60 s.

[0010] Plasma activation using oxygen can form active sites such as -OH, O·, and -COOH on the surface of the epoxy resin matrix after plasma treatment, resulting in a better activation effect.

[0011] Preferably, the plasma activation in step S1 is performed at a frequency of 10-15 MHz.

[0012] Preferably, step S1, before plasma activation of the epoxy resin matrix, further includes a pretreatment step, wherein the pretreatment includes cleaning and drying with an organic solvent, wherein the organic solvent includes at least one of acetone and isopropanol.

[0013] More preferably, the cleaning is ultrasonic cleaning. More preferably, the cleaning involves ultrasonically cleaning the epoxy resin matrix in an organic solvent for 1-10 minutes.

[0014] More preferably, the drying is performed at 70-100°C for 20 min-2 h.

[0015] Preferably, the epoxy resin matrix in step S1 comprises bisphenol A type epoxy resin.

[0016] In a specific embodiment of the present invention, the epoxy resin matrix is ​​a cured epoxy resin, and the curing agent can be a conventional amine or acid anhydride in the art, which is not limited in this application.

[0017] Preferably, the alkoxyfluorosilane vapor atmosphere in step S2 satisfies at least one of the following (1)-(4): (1) The alkoxyfluorosilane in step S2 includes perfluorooctyltriethoxysilane; (2) The pressure of the alkoxyfluorosilane vapor atmosphere in step S2 is 8-15 Torr; (3) The temperature of the alkoxyfluorosilane vapor atmosphere in step S2 is 40-60℃; (4) The grafting time described in step S2 is 60-120 min.

[0018] Preferably, in step S2, the mass ratio of the surface-activated matrix to the alkoxyfluorosilane is 100:(0.5-2).

[0019] Preferably, step S2 further includes a nitrogen treatment step after grafting, wherein the nitrogen treatment includes replacing the alkoxyfluorosilane vapor atmosphere with an equimolar amount of nitrogen, and placing the matrix in the nitrogen atmosphere for 5-15 minutes.

[0020] Preferably, the silane containing alkoxy groups in step S3 includes at least one of silane A, silane B, and silane C, wherein: silane A includes alkylalkoxysilane, silane B includes at least one of epoxyalkoxysilane and aminoalkoxysilane, and silane C includes alkoxysilane.

[0021] The inventors of this application discovered through experiments that using different alkoxysilanes in combination can obtain epoxy resin protective layers with better overall performance. Specifically, the alkyl portion of the alkylalkoxysilane, as a non-polar segment, helps to reduce the overall surface energy of the coating and improve its hydrophobicity. The epoxyalkoxysilane and aminoalkoxysilane selected for silane B can react with the active groups such as hydroxyl and epoxy groups on the surface of epoxy resin through epoxy and amino groups, respectively, to form chemical bond crosslinking sites, thereby enhancing the bonding force between the alkoxysilane coating and the epoxy resin matrix. Furthermore, the active reaction sites in silane B can also participate in crosslinking during the coating curing process, which helps to increase the structural stability of the film. The alkoxysilane used for silane C is mainly because it can provide a basic framework structure for the coating through the hydrolysis of multiple alkoxy groups.

[0022] More preferably, the alkylalkoxysilane includes methyltriethoxysilane.

[0023] More preferably, the epoxyalkoxysilane includes 3-glycidoxypropyltrimethoxysilane.

[0024] More preferably, the aminoalkoxysilane includes 3-aminopropyltriethoxysilane.

[0025] More preferably, the alkoxysilane includes at least one of methyl orthosilicate, ethyl orthosilicate, and propyl orthosilicate.

[0026] More preferably, the alkoxy-containing silane in step S3 includes silane A, silane B and silane C in a mass ratio of (4-8):(1-3):2.

[0027] Preferably, step S3 satisfies at least one of the following (1)-(2): (1) The solvent in step S3 includes water and ethanol; (2) The mass ratio of the alkoxy-containing silane to the solvent in step S3 is 40: (100-200).

[0028] More preferably, the solvent comprises water and ethanol in a volume ratio of 12:(100-150).

[0029] Preferably, step S3 satisfies at least one of the following (1)-(2): (1) In step S3, hydrochloric acid is used to adjust the pH to <7; (2) Step S3, adjusting pH < 7, means adjusting the pH to 3.5 ± 0.3.

[0030] More preferably, step S3, after adjusting the pH to <7 and before aging, further includes a stirring and mixing step, wherein the stirring and mixing is magnetic stirring for 0.5-2 h.

[0031] Preferably, step S3 satisfies at least one of the following (1)-(2): (1) The aging time in step S3 is 6-10 h; (2) The viscosity of the silane gel obtained in step S3 is 5-15 cP.

[0032] Preferably, step S3 satisfies at least one of the following (1)-(3): (1) The coating in step S3 is either spin coating or dip coating, wherein: when the coating is spin coating, the spin coating speed is 2000-3000 rpm; when the coating is dip coating, the dip coating speed is 60-80 mm / min; (2) The thickness of the coating formed after the silane gel is coated on the substrate surface in step S3 is 2-3 μm; (3) The curing in step S3 is carried out at a temperature of 90-100℃ for 60-90 min.

[0033] Preferably, step S3 further includes a degassing step after coating, wherein the degassing is carried out at a temperature of 80-90°C and a pressure of <1 Torr for 2-4 hours.

[0034] Compared with the prior art, the present invention has the following beneficial effects: The epoxy resin surface protection method provided by this invention can provide excellent surface protection for epoxy resin, increasing the initial surface flashover voltage of epoxy resin to above 40.2kV, while reducing the amount of carbon deposited on the epoxy resin surface, reducing the carbonization coverage rate of the epoxy resin surface to below 6.3%, and the carbon deposition areal density to below 500mg / mm². 2 the following. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the electrode before flashover discharge and the surface of the untreated epoxy resin matrix.

[0036] Figure 2 This is a schematic diagram of the electrode and the untreated epoxy resin matrix surface after flashover discharge. Detailed Implementation

[0037] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents. The raw material information used in each embodiment and comparative example is as follows: Epoxy resin raw material: Bisphenol A epoxy diglycidyl ether (DGEBPA, epoxy equivalent 186-190 g / eq) produced by Nantong Xingchen Synthetic Materials Co., Ltd.

[0038] Curing agent: Methylhexahydrophthalic anhydride (MeHHPA, 168.19 g / mol) produced by Puyang Huicheng Electronic Materials Co., Ltd.

[0039] Accelerator: N,N-dimethylbenzylamine (135g / mol, 99% purity) produced by Aladdin Biochemical Technology Co., Ltd.

[0040] Epoxy resin matrix: 30 mm × 30 mm × 1 mm, prepared by mixing epoxy resin raw materials, curing agent and accelerator in a ratio of 100:85:2 and reacting them.

[0041] Example 1 A method for surface protection with epoxy resin includes the following steps: S1. The epoxy resin matrix was immersed in acetone and ultrasonically cleaned for 5 min, then immersed in isopropanol and ultrasonically cleaned for 5 min. After that, it was placed in a 90℃ oven and dried for 30 min. After that, it was removed and cooled to room temperature in a dry environment. Oxygen (O2) was introduced into the plasma cleaner and the flow rate was set to 100 sccm. The chamber pressure was stabilized at 150 mTorr (±10 mTorr). The radio frequency power supply was set to 13.56 MHz and 80 W. The epoxy resin sample was placed flat on a quartz tray and treated at room temperature. The plasma activation of the epoxy resin matrix was completed 40 s from the start of radio frequency power stabilization, and the surface-activated matrix was obtained. S2. Place 2 g of perfluorooctyltriethoxysilane (PFOTES) in an open boat in a vacuum chamber and place the boat in the lower support, with the surface-activated substrate in the upper support; evacuate to 10 Torr and stabilize the chamber temperature at 50 °C, maintaining the reaction for 90 min; then stop heating, replace with dry nitrogen for 10 min, and remove the sample to obtain a substrate grafted with alkoxyfluorosilane. S3. Mix 24 g of methyltriethoxysilane (MTES), 8 g of 3-glycidoxypropyltrimethoxysilane (GPTMS), and 8 g of tetraethoxysilane (TEOS). Add 120 g of anhydrous ethanol and 12 g of deionized water. Slowly add hydrochloric acid and adjust the pH to 3.5 ± 0.3. After magnetic stirring at room temperature for 1 h, allow the mixture to stand for 8 h to age. The viscosity of the silane gel is measured to be ~10 cP. Dip coating is performed at a pumping speed of 60 mm / min to form a coating with a thickness of ~2.5 μm on the surface of the epoxy resin matrix. Then, place the sample in a hot air circulating oven at 90℃ for 75 min to cure. Then, transfer it to a vacuum oven and continue vacuum drying at 85℃ and 0.5 Torr for 3 h to obtain an epoxy resin with a protective layer on the surface.

[0042] Example 2 A surface protection method for epoxy resin, wherein the only difference from Example 1 is: Step S3 replaces 3-glycidoxypropyltrimethoxysilane with an equal mass of 3-aminopropyltriethoxysilane (APTES).

[0043] Example 3 A surface protection method for epoxy resin, wherein the only difference from Example 1 is: The silanes containing alkoxy groups in step S3 include 20 g of methyltriethoxysilane (MTES), 10 g of 3-glycidoxypropyltrimethoxysilane (GPTMS), and 10 g of tetraethoxysilane (TEOS).

[0044] Example 4 A surface protection method for epoxy resin, wherein the only difference from Example 1 is: The silanes containing alkoxy groups in step S3 include methyltriethoxysilane (MTES) 30 g, 3-glycidoxypropyltrimethoxysilane (GPTMS) 5 g, and tetraethoxysilane (TEOS) 5 g.

[0045] Example 5 A surface protection method for epoxy resin, wherein the only difference from Example 1 is: The silanes containing alkoxy groups in step S3 include methyltriethoxysilane (MTES) 13.5 g, 3-glycidoxypropyltrimethoxysilane (GPTMS) 13.5 g, and tetraethoxysilane (TEOS) 13.5 g.

[0046] Example 6 A surface protection method for epoxy resin, wherein the only difference from Example 1 is: The silanes containing alkoxy groups in step S3 include 20 g of methyltriethoxysilane (MTES) and 20 g of tetraethoxysilane (TEOS).

[0047] Example 7 A surface protection method for epoxy resin, wherein the only difference from Example 1 is: The silanes containing alkoxy groups in step S3 include 20 g of 3-glycidoxypropyltrimethoxysilane GPTMS and 20 g of tetraethoxysilane TEOS.

[0048] Example 8 A surface protection method for epoxy resin, wherein the only difference from Example 1 is: In step S1, the plasma activation chamber pressure is 130 mTorr (±10 mTorr), the carrier gas flow rate is 120 sccm, the power is 80W, and the plasma activation is completed 30 s from the start of RF power stabilization.

[0049] Example 9 A surface protection method for epoxy resin, wherein the only difference from Example 1 is: In step S1, the plasma activation chamber pressure is 190 mTorr (±10 mTorr), the carrier gas flow rate is 150 sccm, the power is 120W, and the plasma activation is completed 70 s from the start of RF power stabilization.

[0050] Example 10 A surface protection method for epoxy resin, wherein the only difference from Example 1 is: In step S1, the cavity pressure for plasma activation is 110 mTorr (±10 mTorr), the carrier gas flow rate is 60 sccm, the power is 40W, and the plasma activation is completed 20 s from the start of RF power stabilization.

[0051] Example 11 A surface protection method for epoxy resin, wherein the only difference from Example 1 is: In step S2, the vacuum was evacuated to 15 Torr and the chamber temperature was stabilized at 60°C, and the reaction was maintained for 120 min.

[0052] Example 12 A surface protection method for epoxy resin, wherein the only difference from Example 1 is: In step S2, the vacuum is evacuated to 6 Torr and the chamber temperature is stabilized at 30°C, and the reaction is maintained for 30 min.

[0053] Example 13 A surface protection method for epoxy resin, wherein the only difference from Example 1 is: In step S2, the vacuum is evacuated to 20 Torr and the chamber temperature is stabilized at 80°C, and the reaction is maintained for 150 min.

[0054] Comparative Example 1 A surface protection method for epoxy resin, wherein the only difference from Example 1 is: In step S1, plasma activation is not performed. After the substrate is cleaned and dried, it is placed in a vacuum chamber for vapor grafting of alkoxyfluorosilanes.

[0055] Comparative Example 2 A surface protection method for epoxy resin, wherein the only difference from Example 1 is: In step S2, no vapor grafting is performed. After obtaining the surface-activated matrix in step S1, a silane gel is directly prepared and coated onto the surface of the surface-activated matrix, followed by the remaining steps.

[0056] Comparative Example 3 A surface protection method for epoxy resin, wherein the only difference from Example 1 is: Step S3 is omitted. The sample obtained in this comparative example is an epoxy resin matrix with surface grafted alkoxy fluorosilanes.

[0057] Comparative Example 4 A surface protection method for epoxy resin, wherein the only difference from Example 1 is: In step S3, the raw materials for preparing the sol are mixed and magnetically stirred at room temperature for 1 h. Then, the mixture is dipped onto the surface of the epoxy resin matrix at a speed of 60 mm / min to obtain an epoxy resin matrix with silane sol on the surface. The matrix is ​​then allowed to stand at room temperature for 8 h until a gel is formed on the surface of the epoxy resin matrix. The remaining steps, such as curing, are then performed.

[0058] Performance testing Initial surface flashover voltage test (Uf): An AC flashover experimental platform was built, using finger electrodes with a 10mm gap. The voltage was slowly increased at 0.4 MPa in a 3.5% C4F7N / 96.5% CO2 gas environment until the first discharge. The initial surface flashover voltage Uf of the epoxy resin with a protective layer obtained in the examples and comparative examples was recorded. The voltage was reduced to 0 kV, and the test was repeated 50 times, with the average value taken. The morphology of the electrodes and the untreated epoxy resin matrix surface before and after flashover discharge is shown in the figure. Figure 1 , 2 As shown.

[0059] Carbonization coverage test (fC): The carbonization coverage of the sample after 50 flashover discharges in Test 1 was tested. A ring-shaped shadowless light source was used for illumination, and the surface of the epoxy material after flashover discharge was photographed from a vertical angle using an industrial camera. Standardized imaging and threshold segmentation were used to quantitatively obtain the surface carbonization coverage fC.

[0060] Where fC is the surface carbonization area coverage, A1 is the test surface area of ​​the epoxy material (mm2), and AC is the carbonization area of ​​the epoxy material (mm2). 2 ).

[0061] Carbon deposition areal density test (∑C): The carbonization coverage of the sample after 50 flashover discharges in Test 1 was tested. The mass of the epoxy resin material (with protective layer) before the flashover test was measured using a microbalance. After the flashover discharge, the carbonization deposit was removed with a soft brush and the mass of the epoxy resin material (with protective layer) after the flashover test was measured again using a microbalance.

[0062] Where ∑C is the carbon precipitation surface density (μg / mm²), mb is the mass of the epoxy resin material (with protective layer) before flashover test (μg), ma is the mass of the epoxy resin material (with protective layer) after flashover test (μg), and A2 is the discharge exposure area of ​​the epoxy material (mm²).

[0063] The performance test data is shown in Table 1 below: Table 1. As shown in Table 1 above, the epoxy resin surface protection method provided by this invention can provide excellent surface protection for epoxy resin, increasing the initial surface flashover voltage of epoxy resin to above 40.2kV. Simultaneously, it can reduce the amount of carbon deposited on the epoxy resin surface, reducing the carbonization coverage to below 6.3% and the carbon deposition areal density to 500mg / mm². 2 the following.

[0064] According to Examples 1-5, when the silanes containing alkoxy groups in step S3 include silane A, silane B and silane C in the preferred mass ratio of (4-8):(1-3):2, they can have a better epoxy resin surface protection effect.

[0065] According to Examples 6-7, the effect is even better when the silane contains the preferred combination of alkylalkoxysilane, epoxyalkoxysilane, aminoalkoxysilane, and alkoxysilane of the present invention.

[0066] According to Examples 8-10, when plasma activation is carried out under the preferred conditions of 120-180 mTorr, 80-120 sccm, 60-100 W, and 30-60 s, better results can be obtained.

[0067] According to Examples 11-13, the grafting reaction conditions in step S2 are the preferred conditions of the present invention: pressure of 8-15 Torr, temperature of 40-60℃, and time of 60-120 min, which provide better surface protection for epoxy resin.

[0068] According to Comparative Examples 1-3, the absence of any one of the three steps in this invention will result in the inability to obtain satisfactory results.

[0069] According to Comparative Example 4, directly coating the epoxy resin surface with silane sol and allowing it to form a gel did not achieve the excellent results of this application, indicating that the surface-modified epoxy resin has a better bonding effect with the silane gel.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for surface protection of epoxy resin, characterized in that, Includes the following steps: S1. Plasma activation is performed on the epoxy resin matrix to obtain a surface-activated matrix; S2. The surface-activated matrix obtained in step S1 is placed in an alkoxyfluorosilane vapor atmosphere for grafting to obtain a matrix with surface-grafted alkoxyfluorosilane. S3. Disperse silane containing alkoxy groups in a solvent to obtain silane sol, adjust the pH to <7 and age to obtain silane gel; coat the silane gel onto the surface of the substrate grafted with fluorosilane obtained in step S2, and after curing, obtain an epoxy resin with a protective layer on the surface; the solvent includes water.

2. The surface protection method for epoxy resin as described in claim 1, characterized in that, The plasma activation described in step S1 satisfies at least one of the following (1)-(5): (1) The carrier gas for plasma activation in step S1 includes oxygen; (2) The plasma activation described in step S1 is carried out under a cavity pressure of 120-180 mTorr; (3) The plasma activation described in step S1 is carried out under the condition of a carrier gas flow rate of 80-120 sccm; (4) The plasma activation described in step S1 is carried out under a power of 60-100W; (5) The plasma activation time in step S1 is 30-60 s.

3. The surface protection method for epoxy resin as described in claim 1, characterized in that, The alkoxyfluorosilane vapor atmosphere described in step S2 satisfies at least one of the following (1)-(4): (1) The alkoxyfluorosilane in step S2 includes perfluorooctyltriethoxysilane; (2) The pressure of the alkoxyfluorosilane vapor atmosphere in step S2 is 8-15 Torr; (3) The temperature of the alkoxyfluorosilane vapor atmosphere in step S2 is 40-60℃; (4) The grafting time described in step S2 is 60-120 min.

4. The surface protection method for epoxy resin as described in claim 1, characterized in that, The alkoxy-containing silane in step S3 includes at least one of silane A, silane B, and silane C, wherein: silane A includes alkylalkoxysilane, silane B includes at least one of epoxyalkoxysilane and aminoalkoxysilane, and silane C includes alkoxysilane.

5. The surface protection method for epoxy resin as described in claim 4, characterized in that, The alkoxy-containing silanes in step S3 include silane A, silane B, and silane C in a mass ratio of (4-8):(1-3):

2.

6. The surface protection method for epoxy resin as described in claim 1, characterized in that, Step S3 satisfies at least one of the following (1)-(2): (1) The solvent in step S3 includes water and ethanol; (2) The mass ratio of the alkoxy-containing silane to the solvent in step S3 is 40: (100-200).

7. The surface protection method for epoxy resin as described in claim 1, characterized in that, Step S3 satisfies at least one of the following (1)-(2): (1) In step S3, hydrochloric acid is used to adjust the pH to <7; (2) Step S3, adjusting pH < 7, means adjusting the pH to 3.5 ± 0.

3.

8. The surface protection method for epoxy resin as described in claim 1, characterized in that, Step S3 satisfies at least one of the following (1)-(2): (1) The aging time in step S3 is 6-10 h; (2) The viscosity of the silane gel obtained in step S3 is 5-15 cP.

9. The surface protection method for epoxy resin as described in claim 1, characterized in that, Step S3 satisfies at least one of the following (1)-(3): (1) The coating in step S3 is either spin coating or dip coating, wherein: when the coating is spin coating, the spin coating speed is 2000-3000 rpm; when the coating is dip coating, the dip coating speed is 60-80 mm / min; (2) The thickness of the coating formed after the silane gel is coated on the substrate surface in step S3 is 2-3 μm; (3) The curing in step S3 is carried out at a temperature of 90-100℃ for 60-90 min.

10. The surface protection method for epoxy resin as described in claim 1, characterized in that, Satisfy at least one of the following (1)-(3): (1) Step S1 includes a pretreatment step before plasma activation of the epoxy resin matrix. The pretreatment includes cleaning and drying with an organic solvent, and the organic solvent includes at least one of acetone and isopropanol. (2) The epoxy resin matrix in step S1 includes bisphenol A type epoxy resin; (3) Step S3 includes a degassing step after coating. The degassing is carried out at a temperature of 80-90℃ and a pressure of <1 Torr for 2-4 hours.

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