A silicon steel sheet doped with rare earth metal elements and a preparation method thereof

Abstract

The present invention relates to the technical field of electrical steel manufacturing, and specifically to a silicon steel sheet doped with rare earth metal elements and a preparation method thereof. Through various technological treatments on the silicon steel raw materials, the present invention obtains a pretreated silicon steel sheet. Then, by adding polytetrahydrofuran, hydroxypropyl-terminated silicone oil, diisobutyltin dilaurate, hexamethylene diisocyanate, a modified silica solution, a fluorine-containing solution, and / or silanized epoxy resin, an organosilicon-modified polyurethane is prepared. By adding the organosilicon-modified polyurethane, a dispersion aid, a rheological aid, barium sulfate precipitate, talcum powder, and an anticorrosive pigment, two coatings are prepared. The two coatings are sequentially coated on the surface of the pretreated silicon steel sheet to obtain a finished product. The finished product prepared by the present invention has good corrosion resistance and surface adhesion properties, and thus has broad application prospects in the technical field of electrical steel manufacturing.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical steel manufacturing, and particularly to a silicon steel sheet doped with rare earth metal elements and a preparation method thereof. Background Art

[0002] Silicon steel sheets, also known as electrical steel plates, are special steels containing a certain proportion of silicon. They have excellent magnetic properties, low iron loss, high magnetic permeability, etc., and are widely used in the fields of power, electronics, and electrical equipment manufacturing. With the rapid development of modern technology, the role of silicon steel sheets in the industrial and energy fields has become increasingly prominent, mainly reflected in:

[0003] 1. In modern power systems, the manufacturing of high-efficiency transformers highly depends on silicon steel sheets. Especially in the field of renewable energy generation (such as wind energy, solar energy), high-efficiency motors and transformers are the core to improve energy conversion efficiency. The low iron loss property of silicon steel sheets helps to reduce energy loss during power transmission and conversion, thereby reducing carbon emissions and conforming to the global trend of energy conservation and emission reduction.

[0004] 2. The rapid expansion of the new energy vehicle industry has put forward higher requirements for high-efficiency motors, and silicon steel sheets are one of the key materials for manufacturing high-efficiency motors. The high magnetic permeability and low iron loss properties of silicon steel sheets can effectively improve the energy efficiency of electric vehicle drive motors, extend the driving range, and reduce battery energy consumption. In addition, the excellent mechanical properties of silicon steel sheets can also improve the heat dissipation and durability of motors, adapt to the complex working environment of new energy vehicles, and further promote industrial upgrading.

[0005] 3. The wide application of silicon steel sheets in transformer manufacturing directly promotes the improvement of the efficiency of power transmission and distribution systems. By reducing the energy loss of transformers during power transmission, silicon steel sheets can effectively improve the overall efficiency of the power grid, reduce power waste, and lower energy costs.

[0006] However, when silicon steel sheets are used in harsh environments (such as high humidity, large temperature changes, or contact with corrosive media), they are prone to corrosion. This corrosion will cause a reduction in the mechanical properties of the metal, increase power loss, and may even lead to equipment failure in severe cases. Therefore, improving the corrosion resistance of silicon steel sheets is crucial for slowing down the corrosion process, extending the service life of equipment, and reducing replacement and maintenance costs. In addition, ensuring the adhesion performance of the coating is equally important. Good adhesion performance can ensure that the coating is not easily peeled off during use, which is crucial for protecting the substrate from external erosion, improving wear resistance, etc. The excellent adhesion of the coating can enable it to maintain the expected function during long-term operation and reduce the decline in equipment performance caused by coating peeling.

[0007] In order to overcome the defects of the prior art, the present invention provides a silicon steel sheet doped with rare earth metal elements and a preparation method thereof. Summary of the Invention

[0008] The object of the present invention is to provide a silicon steel sheet doped with rare earth metal elements and a preparation method thereof to solve the problems in the prior art.

[0009] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0010] A preparation method of a silicon steel sheet doped with rare earth metal elements, comprising the following steps:

[0011] Step 1: Vacuum smelt, hot-roll, normalize, heat-treat at high temperature, cool by water quenching, temper, and pickling the silicon steel raw material in sequence to obtain a pretreated silicon steel sheet;

[0012] Step 2: Dry polytetrahydrofuran and hydroxypropyl-terminated silicone oil at 120 - 130 °C, then add diisobutyltin dilaurate, hexamethylene diisocyanate, and tetrahydrofuran, stir and react at 80 - 90 °C for 2 - 3 h, then add a modified silica solution, a fluorine-containing solution, and / or a silanized epoxy resin, fully stir at 80 - 90 °C for 2 - 3 h, and after the reaction is completed, dry at 25 - 30 °C for 25 - 30 h to obtain an organosilicon-modified polyurethane;

[0013] By adding a modified silica solution, a fluorine-containing solution, and a silanized epoxy resin solution, an organosilicon-modified polyurethane A is prepared; by adding a modified silica solution and a fluorine-containing solution, an organosilicon-modified polyurethane B is prepared;

[0014] Step 3: Mix and grind organosilicon-modified polyurethane A, a dispersion aid, a rheology aid, barium sulfate precipitate, talcum powder, and an anticorrosive pigment to obtain Coating A; mix and grind organosilicon-modified polyurethane B, a dispersion aid, a rheology aid, barium sulfate precipitate, talcum powder, and an anticorrosive pigment to obtain Coating B; coat Coating A on the surface of the pretreated silicon steel sheet and cure at 180 - 200 °C for 1 - 2 h to obtain an adhesion layer; then coat Coating B and cure at 180 - 200 °C for 1 - 2 h to obtain a corrosion-resistant layer.

[0015] Preferably, in Step 1, the silicon steel raw material comprises 7 - 10 wt% Si, 0.7 - 1.0 wt% Cu, 0.3 - 0.6 wt% rare earth element, and the balance is Fe.

[0016] More preferably, in step one, the rare earth element is specifically any one of Ce, La, Y, Dy, and Nd; vacuum smelting: temperature is 1400 - 1600 °C, time is 30 - 40 min; hot rolling processing temperature is 900 - 1100 °C; normalizing heat treatment: temperature is 900 - 1000 °C, time is 10 - 20 min; high-temperature heat treatment: 900 - 1000 °C, time is 1 - 2 h; cooling and water quenching treatment: cooling to 600 - 650 °C and then water quenching and cooling to 25 - 30 °C; tempering heat treatment: temperature is 200 - 300 °C, time is 0.5 - 1 h.

[0017] More preferably, in step two, the component contents of the silicone-modified polyurethane are as follows: by mass parts, 13 - 15 parts of polytetrahydrofuran, 25 - 30 parts of hydroxypropyl-terminated silicone oil, 0.005 - 0.007 parts of diisobutyltin dilaurate, 18 - 25 parts of hexamethylene diisocyanate, 105 - 115 parts of tetrahydrofuran, 12 - 16 parts of modified silica solution, 14 - 19 parts of fluorine-containing solution and / or 18 - 28 parts of silanized epoxy resin solution.

[0018] More preferably, when preparing the silicone-modified polyurethane A, the reaction mass ratio of the modified silica, 2,3,5,6-tetrafluoroterephthalyl alcohol, and silanized epoxy resin is 1:1.2:(1.5 - 1.7); when preparing the silicone-modified polyurethane B, the reaction mass ratio of the modified silica and 2,3,5,6-tetrafluoroterephthalyl alcohol is 1:(1.2 - 1.4).

[0019] More preferably, the modified nano-silica is dissolved in tetrahydrofuran to obtain a modified silica solution; 2,3,5,6-tetrafluoroterephthalyl alcohol is dissolved in tetrahydrofuran to obtain a fluorine-containing solution; the silanized epoxy resin is dissolved in acetone to obtain a silanized epoxy resin solution.

[0020] More preferably, the preparation process of the silanized epoxy resin is as follows: in a nitrogen environment, epoxy resin and butyl acetate are mixed, heated to a liquid state at 40 - 50 °C, and then 3-aminopropyltriethoxysilane is added, and stirring and reacting continue for 3 - 4 h to obtain the silanized epoxy resin; the reaction mass ratio of the epoxy resin, butyl acetate, and 3-aminopropyltriethoxysilane is 10:1:(1.0 - 1.5).

[0021] Preferably, the preparation process of the modified nano-silica is as follows: Mix nano-silica filler and toluene, and stir evenly to obtain a nano-silica solution; Mix 3-mercaptopropyltrimethoxysilane and toluene, and stir evenly to obtain a 3-mercaptopropyltrimethoxysilane solution; Heat the nano-silica solution to 100-110 °C, then add the 3-mercaptopropyltrimethoxysilane solution, and continue to react for 10-14 h. After the reaction is completed, centrifuge, purify, and dry to obtain the modified nano-silica; The reaction mass ratio of the nano-silica filler to 3-mercaptopropyltrimethoxysilane is 2:(5-6).

[0022] Preferably, in step three, the component contents of coating A are as follows: by mass fraction, 65-75% organosilicon-modified polyurethane A, 0.7-1.0% dispersion aid, 0.3-0.5% rheology aid, 5-7% barium sulfate precipitate, 5-7% talc powder, and the balance is anticorrosive pigment; The component contents of coating B are as follows: by mass fraction, 65-75% organosilicon-modified polyurethane B, 0.7-1.0% dispersion aid, 0.3-0.5% rheology aid, 5-7% barium sulfate precipitate, 5-7% talc powder, and the balance is anticorrosive pigment.

[0023] Preferably, in step three, the thickness of the adhesion layer is 40-60 μm, and the thickness of the corrosion-resistant layer is 90-100 μm.

[0024] The beneficial effects of the present invention are as follows:

[0025] The characteristics of the present invention are that in step two, an organosilicon-modified polyurethane is prepared by adding polytetrahydrofuran, hydroxypropyl-terminated silicone oil, diisobutyltin dilaurate, hexamethylene diisocyanate, a modified silica solution, a fluorine-containing solution, and / or a silanized epoxy resin. The reaction mechanism of this process is as follows: Under the catalytic action of diisobutyltin dilaurate, the hydroxyl groups of polytetrahydrofuran and hydroxypropyl-terminated silicone oil and the isocyanate groups of hexamethylene diisocyanate undergo a polycondensation reaction to obtain an isocyanate-terminated polyurethane intermediate; Then, a modified silica solution, a fluorine-containing solution, and / or a silanized epoxy resin solution containing hydroxyl groups are further added to obtain an organosilicon-modified polyurethane. The modified silica material can effectively block the penetration of corrosive media and enhance the corrosion resistance of the organosilicon-modified polyurethane. The fluorine-containing material has an extremely low surface energy, which can significantly reduce the wettability of the material surface, making it more difficult for water and other corrosive liquids to spread and penetrate on the material surface, thereby improving the corrosion resistance of the material. The silanized epoxy resin contains many polar groups such as epoxy groups and hydroxyl groups, so it can effectively increase the molecular polarity and improve the adhesion performance of the material surface.

[0026] Among them, a silanized epoxy resin is prepared by adding epoxy resin, butyl acetate and 3-aminopropyltriethoxysilane. In this step, after hydrolysis of 3-aminopropyltriethoxysilane, silanol groups and alcohols are generated. Further, ring-opening reaction occurs between the epoxy groups of the epoxy resin and the silanol groups to obtain a silanized epoxy resin containing hydroxyl groups. A mercapto-modified modified silica solution is obtained by adding 3-mercaptopropyltrimethoxysilane, nano-silica filler and toluene.

[0027] The characteristics of the present invention are that in step three, an organosilicon-modified polyurethane A is prepared by adding polytetrahydrofuran, hydroxypropyl-terminated silicone oil, diisobutyltin dilaurate, hexamethylene diisocyanate, modified silica solution, fluorine-containing solution and silanized epoxy resin solution. In this step, by setting the reaction mass ratio of modified silica, 2,3,5,6-tetrafluoroterephthalyl alcohol and silanized epoxy resin to 1:1.2:(1.5-1.7), a material with good adhesion performance and corrosion resistance is prepared. Preparing this material into a coating can significantly improve the material polarity, enhance the interaction between the coating and the pretreated silicon steel sheet, and improve the coating adhesion performance. An organosilicon-modified polyurethane B is prepared by adding polytetrahydrofuran, hydroxypropyl-terminated silicone oil, diisobutyltin dilaurate, hexamethylene diisocyanate, modified silica solution and fluorine-containing solution. In this step, by setting the reaction mass ratio of modified silica and 2,3,5,6-tetrafluoroterephthalyl alcohol to 1:(1.2-1.4), the enhancement effect of modified silica and the corrosion resistance of fluorine element can reach the best balance, making the coating have excellent mechanical properties and corrosion resistance, thereby significantly improving the corrosion resistance of the surface of the pretreated silicon steel sheet. Detailed implementation manners

[0028] The technical solutions in the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work shall fall within the protection scope of the present invention.

[0029] Source of raw materials:

[0030] Epoxy resin is provided by Jinan Zesheng Chemical Co., Ltd., with the model of E51; the particle size of the nano-silica filler is 0.8 μm; polytetrahydrofuran, Mw = 1000 g / mol; hydroxypropyl-terminated silicone oil, Mw = 2000 g / mol; the dispersion aid is specifically LOPON 895 dispersion aid; the rheology aid is specifically BENTONE LT rheology aid; the fineness of talcum powder is 400 mesh; the anti-corrosion pigment is provided by Guangzhou Situlong Chemical Co., Ltd., with the model of Halox SZP-391; by mass fraction, one part is 1 g.

[0031] Example 1: Step 1: The silicon steel raw material is successively subjected to vacuum smelting at 1600 °C for 40 min, hot rolling at 1100 °C, normalizing heat treatment at 1000 °C for 20 min, high-temperature heat treatment at 1000 °C for 2 h, cooling to 650 °C and then water quenching to 30 °C, tempering heat treatment at 300 °C for 1 h, and pickling treatment to obtain a pretreated silicon steel sheet; the silicon steel raw material includes 10 wt% Si, 1 wt% Cu, 0.6 wt% rare earth element Ce, and 88.4 wt% Fe;

[0032] Step 2: In a nitrogen environment, 10 g of epoxy resin and 1 g of butyl acetate are mixed and heated to a liquid state at 50 °C, and then 1.3 g of 3-aminopropyltriethoxysilane is added, and the stirring reaction is continued for 4 h to obtain silanized epoxy resin;

[0033] 2 g of nano-silica filler and toluene are mixed and stirred evenly to obtain a nano-silica solution; 5.5 g of 3-mercaptopropyltrimethoxysilane and toluene are mixed and stirred evenly to obtain a 3-mercaptopropyltrimethoxysilane solution; the nano-silica solution is heated to 110 °C, and then the 3-mercaptopropyltrimethoxysilane solution is added, and the reaction is continued for 14 h. After the reaction is completed, it is centrifuged, purified, and dried to obtain modified nano-silica;

[0034] Among them, 4 g of modified nano-silica is dissolved in 8 g of tetrahydrofuran to obtain a modified silica solution; 4.8 g of 2,3,5,6-tetrafluoroterephthalyl alcohol is dissolved in 10 g of tetrahydrofuran to obtain a fluorine-containing solution; 6.4 g of silanized epoxy resin is dissolved in 12 g of acetone to obtain a silanized epoxy resin solution;

[0035] 13 g of polytetrahydrofuran and 25 g of hydroxypropyl-terminated silicone oil are dried at 130 °C, and then 0.005 g of diisobutyltin dilaurate, 25 g of hexamethylene diisocyanate, and 115 g of tetrahydrofuran are added, and the stirring reaction is carried out at 90 °C for 3 h. Then, the modified silica solution, the fluorine-containing solution, and / or the silanized epoxy resin are added, and the stirring is carried out at 90 °C for 3 h. After the reaction is completed, it is dried at 30 °C for 30 h to obtain organosilicon-modified polyurethane; by adding the modified silica solution, the fluorine-containing solution, and the silanized epoxy resin solution, organosilicon-modified polyurethane A is prepared; by adding the modified silica solution and the fluorine-containing solution, organosilicon-modified polyurethane B is prepared;

[0036] Step 3: Mix and grind 75% organosilicon-modified polyurethane A, 1% dispersing aid, 0.5% rheological aid, 7% barium sulfate precipitate, 7% talcum powder, and 9.5% anti-corrosion pigment by mass fraction to obtain Coating A; mix and grind 75% organosilicon-modified polyurethane B, 1% dispersing aid, 0.5% rheological aid, 7% barium sulfate precipitate, 7% talcum powder, and 9.5% anti-corrosion pigment to obtain Coating B; coat Coating A on the surface of the pretreated silicon steel sheet, and cure it at 200 °C for 2 h to obtain an adhesion layer with a thickness of 60 μm; then coat Coating B and cure it at 200 °C for 2 h to obtain a corrosion-resistant layer with a thickness of 100 μm.

[0037] Example 2: Step 1: Subject the silicon steel raw material to vacuum smelting at 1500 °C for 35 min, hot rolling at 1000 °C, normalizing heat treatment at 950 °C for 15 min, high-temperature heat treatment at 950 °C for 1.5 h, cooling to 625 °C and then water quenching to 27 °C, tempering heat treatment at 250 °C for 0.7 h, and pickling treatment in sequence to obtain a pretreated silicon steel sheet; the silicon steel raw material includes 10 wt% Si, 1 wt% Cu, 0.6 wt% rare earth element Ce, and 88.4 wt% Fe;

[0038] Step 2: Under a nitrogen atmosphere, mix 10 g of epoxy resin and 1 g of butyl acetate, heat it to a liquid state at 45 °C, and then add 1.3 g of 3-aminopropyltriethoxysilane, and continue stirring and reacting for 3.5 h to obtain silanized epoxy resin;

[0039] Mix 2 g of nano-silica filler and toluene, and stir evenly to obtain a nano-silica solution; mix 5.5 g of 3-mercaptopropyltrimethoxysilane and toluene, and stir evenly to obtain a 3-mercaptopropyltrimethoxysilane solution; heat the nano-silica solution to 105 °C, and then add the 3-mercaptopropyltrimethoxysilane solution, and continue reacting for 12 h. After the reaction is completed, centrifuge, purify, and dry to obtain modified nano-silica;

[0040] Dissolve 4 g of modified nano-silica in 8 g of tetrahydrofuran to obtain a modified silica solution; dissolve 4.8 g of 2,3,5,6-tetrafluoroterephthalic alcohol in 10 g of tetrahydrofuran to obtain a fluorine-containing solution; dissolve 6.4 g of silanized epoxy resin in 12 g of acetone to obtain a silanized epoxy resin solution;

[0041] 13 g of polytetrahydrofuran and 25 g of hydroxypropyl-terminated silicone oil were dried at 125 °C, then 0.005 g of diisobutyltin dilaurate, 25 g of hexamethylene diisocyanate and 115 g of tetrahydrofuran were added, and the mixture was stirred and reacted at 85 °C for 2.5 h. Then, a modified silica solution, a fluorine-containing solution and / or a silylated epoxy resin were added, and the mixture was sufficiently stirred at 85 °C for 2.5 h. After the reaction was completed, it was dried at 27 °C for 27 h to obtain a silicone-modified polyurethane; by adding a modified silica solution, a fluorine-containing solution and a silylated epoxy resin solution, a silicone-modified polyurethane A was prepared; by adding a modified silica solution and a fluorine-containing solution, a silicone-modified polyurethane B was prepared;

[0042] Step 3: By mass fraction, 75% of the silicone-modified polyurethane A, 1% of a dispersion aid, 0.5% of a rheology aid, 7% of barium sulfate precipitate, 7% of talc powder and 9.5% of an anti-corrosion pigment were mixed and ground to obtain Coating A; 75% of the silicone-modified polyurethane B, 1% of a dispersion aid, 0.5% of a rheology aid, 7% of barium sulfate precipitate, 7% of talc powder and 9.5% of an anti-corrosion pigment were mixed and ground to obtain Coating B; Coating A was coated on the surface of a pretreated silicon steel sheet and cured at 190 °C for 1.5 h to obtain an adhesion layer with a thickness of 60 μm; then Coating B was coated and cured at 190 °C for 1.5 h to obtain a corrosion-resistant layer with a thickness of 100 μm.

[0043] Example 3: Step 1: The silicon steel raw material was successively subjected to vacuum smelting at 1500 °C for 30 min, hot rolling at 900 °C, normalizing heat treatment at 900 °C for 10 min, high-temperature heat treatment at 900 °C for 1 h, cooling to 600 °C and then water quenching to 25 °C, tempering heat treatment at 200 °C for 0.5 h, and pickling treatment to obtain a pretreated silicon steel sheet; the silicon steel raw material included 10 wt% Si, 1 wt% Cu, 0.6 wt% rare earth element Ce, and 88.4 wt% Fe;

[0044] Step 2: In a nitrogen environment, 10 g of epoxy resin and 1 g of butyl acetate were mixed and heated to a liquid state at 40 °C, then 1.3 g of 3-aminopropyltriethoxysilane was added, and the mixture was continuously stirred and reacted for 3 h to obtain a silylated epoxy resin;

[0045] 2 g of nano-silica filler and toluene were mixed and stirred evenly to obtain a nano-silica solution; 5.5 g of 3-mercaptopropyltrimethoxysilane and toluene were mixed and stirred evenly to obtain a 3-mercaptopropyltrimethoxysilane solution; the nano-silica solution was heated to 100 °C, then the 3-mercaptopropyltrimethoxysilane solution was added, and the reaction was continued for 10 h. After the reaction was completed, it was centrifuged, purified and dried to obtain modified nano-silica;

[0046] Dissolve 4 g of modified nano-silica in 8 g of tetrahydrofuran to obtain a modified silica solution; dissolve 4.8 g of 2,3,5,6-tetrafluoroterephthalyl alcohol in 10 g of tetrahydrofuran to obtain a fluorine-containing solution; dissolve 6.4 g of silanized epoxy resin in 12 g of acetone to obtain a silanized epoxy resin solution;

[0047] Dry 13 g of polytetrahydrofuran and 25 g of hydroxypropyl-terminated silicone oil at 120 °C, then add 0.005 g of diisobutyltin dilaurate, 25 g of hexamethylene diisocyanate and 115 g of tetrahydrofuran, stir and react at 80 °C for 2 h, then add the modified silica solution, the fluorine-containing solution and / or the silanized epoxy resin, stir well at 80 °C for 2 h, and after the reaction is completed, dry at 25 °C for 25 h to obtain organosilicon-modified polyurethane; by adding the modified silica solution, the fluorine-containing solution and the silanized epoxy resin solution, organosilicon-modified polyurethane A is prepared; by adding the modified silica solution and the fluorine-containing solution, organosilicon-modified polyurethane B is prepared;

[0048] Step 3: Mix and grind 75% organosilicon-modified polyurethane A, 1% dispersing aid, 0.5% rheological aid, 7% barium sulfate precipitate, 7% talc powder and 9.5% anti-corrosion pigment by mass fraction to obtain Coating A; mix and grind 75% organosilicon-modified polyurethane B, 1% dispersing aid, 0.5% rheological aid, 7% barium sulfate precipitate, 7% talc powder and 9.5% anti-corrosion pigment to obtain Coating B; coat Coating A on the surface of the pretreated silicon steel sheet, cure at 180 °C for 1 h to obtain an adhesion layer with a thickness of 60 μm; then coat Coating B and cure at 180 °C for 1 h to obtain a corrosion-resistant layer with a thickness of 100 μm.

[0049] Comparative Example 1: Adjust the reaction mass ratio of modified silica and 2,3,5,6-tetrafluoroterephthalyl alcohol in the corrosion-resistant layer and the adhesion layer to 1:0.7, and the rest is the same as in Example 1. The specific steps are as follows: Step 1: Vacuum smelt the silicon steel raw material at 1600 °C for 40 min, hot roll at 1100 °C, normalize and heat-treat at 1000 °C for 20 min, heat-treat at 1000 °C for 2 h, cool to 650 °C and then water-quench and cool to 30 °C, temper and heat-treat at 300 °C for 1 h, and perform pickling treatment to obtain a pretreated silicon steel sheet; the silicon steel raw material includes 10 wt% Si, 1 wt% Cu, 0.6 wt% rare earth element Ce, and 88.4 wt% Fe;

[0050] Step 2: Under a nitrogen atmosphere, mix 10 g of epoxy resin and 1 g of butyl acetate, heat to liquid state at 50 °C, then add 1.3 g of 3-aminopropyltriethoxysilane, and continue to stir and react for 4 h to obtain silanized epoxy resin;

[0051] Mix 2 g of nano-silica filler with toluene, and stir evenly to obtain a nano-silica solution; mix 5.5 g of 3-mercaptopropyltrimethoxysilane with toluene, and stir evenly to obtain a 3-mercaptopropyltrimethoxysilane solution; heat the nano-silica solution to 110 °C, then add the 3-mercaptopropyltrimethoxysilane solution, and continue the reaction for 14 h. After the reaction is completed, centrifuge, purify, and dry to obtain modified nano-silica;

[0052] Dissolve 4 g of modified nano-silica in 8 g of tetrahydrofuran to obtain a modified silica solution; dissolve 2.8 g of 2,3,5,6-tetrafluoroterephthalyl alcohol in 10 g of tetrahydrofuran to obtain a fluorine-containing solution; dissolve 6.4 g of silanized epoxy resin in 12 g of acetone to obtain a silanized epoxy resin solution;

[0053] Dry 13 g of polytetrahydrofuran and 25 g of hydroxypropyl-terminated silicone oil at 130 °C, then add 0.005 g of diisobutyltin dilaurate, 25 g of hexamethylene diisocyanate, and 115 g of tetrahydrofuran, stir and react at 90 °C for 3 h, then add the modified silica solution, the fluorine-containing solution, and / or the silanized epoxy resin, stir well at 90 °C for 3 h. After the reaction is completed, dry at 30 °C for 30 h to obtain organosilicon-modified polyurethane; by adding the modified silica solution, the fluorine-containing solution, and the silanized epoxy resin solution, organosilicon-modified polyurethane A is prepared; by adding the modified silica solution and the fluorine-containing solution, organosilicon-modified polyurethane B is prepared;

[0054] Step 3: Mix and grind 75% organosilicon-modified polyurethane A, 1% dispersing aid, 0.5% rheological aid, 7% barium sulfate precipitate, 7% talc powder, and 9.5% anti-corrosion pigment by mass fraction to obtain Coating A; mix and grind 75% organosilicon-modified polyurethane B, 1% dispersing aid, 0.5% rheological aid, 7% barium sulfate precipitate, 7% talc powder, and 9.5% anti-corrosion pigment to obtain Coating B; coat Coating A on the surface of the pretreated silicon steel sheet, and cure at 200 °C for 2 h to obtain an adhesion layer with a thickness of 60 μm; then coat Coating B and cure at 200 °C for 2 h to obtain a corrosion-resistant layer with a thickness of 100 μm.

[0055] Comparative Example 2: Remove the preparation step of the corrosion-resistant layer, and the rest is the same as in Example 1. The specific steps are as follows: Step 1: Subject the silicon steel raw material to vacuum smelting at 1600 °C for 40 min, hot rolling at 1100 °C, normalizing heat treatment at 1000 °C for 20 min, high-temperature heat treatment at 1000 °C for 2 h, cooling to 650 °C and then quenching with water to 30 °C, tempering heat treatment at 300 °C for 1 h, and pickling treatment to obtain a pretreated silicon steel sheet; the silicon steel raw material includes 10 wt% Si, 1 wt% Cu, 0.6 wt% rare earth element Ce, and 88.4 wt% Fe;

[0056] Step 2: Under a nitrogen atmosphere, 10 g of epoxy resin and 1 g of butyl acetate are mixed, heated to a liquid state at 50 °C, then 1.3 g of 3-aminopropyltriethoxysilane is added, and stirring reaction is continued for 4 h to obtain silanized epoxy resin;

[0057] 2 g of nano-silica filler and toluene are mixed and stirred evenly to obtain a nano-silica solution; 5.5 g of 3-mercaptopropyltrimethoxysilane and toluene are mixed and stirred evenly to obtain a 3-mercaptopropyltrimethoxysilane solution; the nano-silica solution is heated to 110 °C, then the 3-mercaptopropyltrimethoxysilane solution is added, and the reaction is continued for 14 h. After the reaction is completed, centrifugation, purification, and drying are carried out to obtain modified nano-silica;

[0058] Among them, 4 g of modified nano-silica is dissolved in 8 g of tetrahydrofuran to obtain a modified silica solution; 4.8 g of 2,3,5,6-tetrafluoroterephthalic alcohol is dissolved in 10 g of tetrahydrofuran to obtain a fluorine-containing solution; 6.4 g of silanized epoxy resin is dissolved in 12 g of acetone to obtain a silanized epoxy resin solution;

[0059] 13 g of polytetrahydrofuran and 25 g of hydroxypropyl-terminated silicone oil are dried at 130 °C, then 0.005 g of diisobutyltin dilaurate, 25 g of hexamethylene diisocyanate, and 115 g of tetrahydrofuran are added, and stirring reaction is carried out at 90 °C for 3 h. Then the modified silica solution, the fluorine-containing solution, and the silanized epoxy resin are added, and sufficient stirring is carried out at 90 °C for 3 h. After the reaction is completed, drying is carried out at 30 °C for 30 h to obtain organosilicon-modified polyurethane;

[0060] Step 3: By mass fraction, 75% of organosilicon-modified polyurethane, 1% of dispersion aid, 0.5% of rheological aid, 7% of barium sulfate precipitate, 7% of talc powder, and 9.5% of anti-corrosion pigment are mixed and ground to obtain a coating; the coating is coated on the surface of the pretreated silicon steel sheet and cured at 200 °C for 2 h to obtain an adhesion layer with a thickness of 60 μm.

[0061] Comparative Example 3: The reaction mass ratio of modified nano-silica, 2,3,5,6-tetrafluoroterephthalic alcohol, and silanized epoxy resin in the adhesion layer is adjusted to 1:1.2:0.5, and the rest is the same as in Example 1. The specific steps are as follows: Step 1: The silicon steel raw material is successively subjected to vacuum smelting at 1600 °C for 40 min, hot rolling at 1100 °C, normalizing heat treatment at 1000 °C for 20 min, high-temperature heat treatment at 1000 °C for 2 h, cooling to 650 °C and then water quenching to 30 °C, tempering heat treatment at 300 °C for 1 h, and pickling treatment to obtain a pretreated silicon steel sheet; the silicon steel raw material includes 10 wt% Si, 1 wt% Cu, 0.6 wt% rare earth element Ce, and 88.4 wt% Fe;

[0062] Step 2: Under a nitrogen environment, 10 g of epoxy resin and 1 g of butyl acetate were mixed, heated at 50° C. until liquid, and then 1.3 g of 3-aminopropyltriethoxysilane was added, and the reaction was continued by stirring for 4 h to obtain a silylated epoxy resin;

[0063] 2 g of nano-silica filler and toluene were mixed and stirred to obtain a nano-silica solution; 5.5 g of 3-mercaptopropyltrimethoxysilane and toluene were mixed and stirred to obtain a 3-mercaptopropyltrimethoxysilane solution; the nano-silica solution was heated to 110° C., and the 3-mercaptopropyltrimethoxysilane solution was added, and the reaction was continued for 14 hours. After the reaction was completed, the modified nano-silica was obtained by centrifugation, purification, and drying;

[0064] 4 g of modified nano-silica was dissolved in 8 g of tetrahydrofuran to obtain a modified silica solution; 4.8 g of 2,3,5,6-tetrafluorophenylenedimethanol was dissolved in 10 g of tetrahydrofuran to obtain a fluorine-containing solution; 2 g of silylated epoxy resin was dissolved in 12 g of acetone to obtain a silylated epoxy resin solution;

[0065] 13g of polytetrahydrofuran and 25g of hydroxypropyl-terminated silicone oil were dried at 130°C, and then 0.005g of diisobutyltin dioctanoate, 25g of hexamethylene diisocyanate and 115g of tetrahydrofuran were added, and the mixture was stirred at 90°C for 3h, and then a modified silica solution, a fluorine-containing solution and / or a silylated epoxy resin were added, and the mixture was fully stirred at 90°C for 3h. After the reaction was completed, the mixture was dried at 30°C for 30h to obtain an organosilicon-modified polyurethane; an organosilicon-modified polyurethane A was prepared by adding a modified silica solution, a fluorine-containing solution and a silylated epoxy resin solution; an organosilicon-modified polyurethane B was prepared by adding a modified silica solution and a fluorine-containing solution;

[0066] Step 3: In terms of mass fraction, 75% of silicone modified polyurethane A, 1% of dispersing agent, 0.5% of rheological agent, 7% of barium sulfate precipitate, 7% of talcum powder and 9.5% of anti-corrosion pigment are mixed and ground to obtain coating A; 75% of silicone modified polyurethane B, 1% of dispersing agent, 0.5% of rheological agent, 7% of barium sulfate precipitate, 7% of talcum powder and 9.5% of anti-corrosion pigment are mixed and ground to obtain coating B; coating A is applied to the surface of the pretreated silicon steel sheet and cured at 200°C for 2h to obtain an adhesion layer with a thickness of 60μm; then coating B is applied and cured at 200°C for 2h to obtain a corrosion-resistant layer with a thickness of 100μm.

[0067] Comparative Example 4: The preparation step of the adhesion layer was removed, and the rest was the same as in Example 1. The specific steps were as follows: Step 1: The silicon steel raw material was successively subjected to vacuum smelting at 1600 °C for 40 min, hot rolling at 1100 °C, normalizing heat treatment at 1000 °C for 20 min, high-temperature heat treatment at 1000 °C for 2 h, cooling to 650 °C and then water quenching to 30 °C, tempering heat treatment at 300 °C for 1 h, and pickling treatment to obtain a pretreated silicon steel sheet; the silicon steel raw material included 10 wt% Si, 1 wt% Cu, 0.6 wt% rare earth element Ce, and 88.4 wt% Fe;

[0068] Step 2: 2 g of nano-silica filler was mixed with toluene, and after stirring evenly, a nano-silica solution was obtained; 5.5 g of 3-mercaptopropyltrimethoxysilane was mixed with toluene, and after stirring evenly, a 3-mercaptopropyltrimethoxysilane solution was obtained; the nano-silica solution was heated to 110 °C, and then the 3-mercaptopropyltrimethoxysilane solution was added, and the reaction continued for 14 h. After the reaction ended, centrifugation, purification, and drying were carried out to obtain modified nano-silica;

[0069] Among them, 4 g of modified nano-silica was dissolved in 8 g of tetrahydrofuran to obtain a modified silica solution; 4.8 g of 2,3,5,6-tetrafluoroterephthalyl alcohol was dissolved in 10 g of tetrahydrofuran to obtain a fluorine-containing solution;

[0070] 13 g of polytetrahydrofuran and 25 g of hydroxypropyl-terminated silicone oil were dried at 130 °C, and then 0.005 g of diisobutyltin dilaurate, 25 g of hexamethylene diisocyanate, and 115 g of tetrahydrofuran were added. The mixture was stirred and reacted at 90 °C for 3 h, then the modified silica solution and the fluorine-containing solution were added, and the mixture was fully stirred at 90 °C for 3 h. After the reaction ended, drying was carried out at 30 °C for 30 h to obtain organosilicon-modified polyurethane;

[0071] Step 3: By mass fraction, 75% of organosilicon-modified polyurethane, 1% of dispersion aid, 0.5% of rheology aid, 7% of barium sulfate precipitate, 7% of talc powder, and 9.5% of anticorrosive pigment were mixed and ground to obtain a coating; the coating was coated on the surface of the pretreated silicon steel sheet and cured at 200 °C for 2 h to obtain a corrosion-resistant layer with a thickness of 100 μm.

[0072] Adhesion performance test: The coating (coating A and / or coating B) prepared by the present invention was coated on one end of the substrate tinplate, and then epoxy glue was coated on the coating surface. The other end of another tinplate was adhered to the above-mentioned tinplate end with epoxy glue. After placing at 30 °C for 2 d, the tinplate was fixed with a Zwick / Roell Z020 universal material testing machine, and the constant rate was set at 50 mm / min. The adhesion performance was evaluated by testing the shear tensile force.

[0073] Corrosion resistance performance test: The coatings prepared according to the present invention (coating A and / or coating B) were coated on the surface of a glass sheet. After standing for 1 day, they were respectively placed in an acid solution with pH = 3 and an alkali solution with pH = 11. After impregnation for 1 day, the water contact angle of the coating surface was measured, and the corrosion resistance performance was evaluated by testing the water contact angle. The results are shown in the following table:

[0074]

[0075] Conclusion: The dosages in Examples 1 to 3 remained unchanged, and only some reaction parameters were modified. From the experimental data, it can be seen that there were no obvious fluctuations in the performance of the specimens.

[0076] Comparative Example 1: The reaction mass ratio of modified silica and 2,3,5,6-tetrafluoroterephthalyl alcohol in the corrosion-resistant layer and the adhesion layer was adjusted to 1:0.7, and the rest was the same as in Example 1. From the experimental data, it can be seen that compared with Example 1, the water contact angle after acid corrosion decreased to 119° and the water contact angle after alkali corrosion decreased to 109°. The reason for the analysis is that when the component dosage of 2,3,5,6-tetrafluoroterephthalyl alcohol in the corrosion-resistant layer and the adhesion layer was reduced, the surface energy of the prepared coating increased, making it more easily eroded by corrosive acids and alkalis. Therefore, the water contact angle decreased and the corrosion resistance performance declined.

[0077] Comparative Example 2: The preparation step of the corrosion-resistant layer was removed, and the rest was the same as in Example 1. From the experimental data, it can be seen that compared with Example 1, the water contact angle after acid corrosion decreased to 110° and the water contact angle after alkali corrosion decreased to 102°. The reason for the analysis is that after removing the corrosion-resistant layer on the surface of the pretreated silicon steel sheet, the surface corrosion resistance of the pretreated silicon steel sheet was significantly reduced, so the water contact angle decreased and the corrosion resistance performance declined.

[0078] Comparative Example 3: The reaction mass ratio of modified silica, 2,3,5,6-tetrafluoroterephthalyl alcohol and silanized epoxy resin in the adhesion layer was adjusted to 1:1.2:0.5, and the rest was the same as in Example 1. From the experimental data, it can be seen that compared with Example 1, the shear tensile force decreased to 0.539 MPa. The reason for the analysis is that after reducing the dosage of silanized epoxy resin in the adhesion layer, the adhesion of the adhesion layer decreased, so the shear tensile force decreased and the coating was more likely to fall off.

[0079] Comparative Example 4: The preparation step of the adhesion layer was removed, and the rest was the same as in Example 1. From the experimental data, it can be seen that compared with Example 1, the shear tensile force decreased to 0.453 MPa. The reason for the analysis is that after removing the adhesion layer, the adhesion performance of the pretreated silicon steel sheet decreased significantly, and the shear tensile force decreased significantly.

[0080] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or elements inherent to such process, method, article or device.

[0081] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a rare earth metal element doped silicon steel sheet, characterized in that: The following steps are involved: Step 1: subjecting the silicon steel raw material to vacuum smelting, hot rolling, normalizing heat treatment, high temperature heat treatment, cooling water quenching, tempering heat treatment, and pickling treatment in sequence to obtain a pretreated silicon steel sheet; Step 2: Dry the polytetrahydrofuran and hydroxypropyl terminated silicone oil at 120-130° C., then add diisobutyltin dioctanoate, hexamethylene diisocyanate and tetrahydrofuran, stir and react at 80-90° C. for 2-3 hours, then add modified silica solution, fluorine-containing solution and / or silylated epoxy resin, stir well at 80-90° C. for 2-3 hours, and after the reaction is completed, dry at 25-30° C. for 25-30 hours to obtain silicone-modified polyurethane; The nano-silica filler and toluene are mixed and stirred to obtain a nano-silica solution; 3-mercaptopropyltrimethoxysilane and toluene are mixed and stirred to obtain a 3-mercaptopropyltrimethoxysilane solution; the nano-silica solution is heated to 100-110°C, and the 3-mercaptopropyltrimethoxysilane solution is added, and the reaction is continued for 10-14 hours. After the reaction is completed, the modified nano-silica is obtained by centrifugation, purification, and drying; the modified nano-silica is dissolved in tetrahydrofuran to obtain a modified silica solution; 2,3,5,6-tetrafluorophenylenedimethanol is dissolved in tetrahydrofuran to obtain a fluorine-containing solution; under a nitrogen environment, epoxy resin and butyl acetate are mixed, heated to a liquid state at 40-50°C, and 3-aminopropyltriethoxysilane is added, and the reaction is continued with stirring for 3-4 hours to obtain a silylated epoxy resin; the silylated epoxy resin is dissolved in acetone to obtain a silylated epoxy resin solution; Organosilicon-modified polyurethane A is prepared by adding modified silica solution, fluorine-containing solution and silylated epoxy resin solution; organosilicon-modified polyurethane B is prepared by adding modified silica solution and fluorine-containing solution; when preparing organosilicon-modified polyurethane A, the reaction mass ratio of modified silica, 2,3,5,6-tetrafluorophenylenedimethanol and silylated epoxy resin is 1:1.2:(1.5-1.7); when preparing organosilicon-modified polyurethane B, the reaction mass ratio of modified silica and 2,3,5,6-tetrafluorophenylenedimethanol is 1:(1.2-1.4); Step 3: Mix and grind the organosilicon-modified polyurethane A, a dispersing agent, a rheological agent, a barium sulfate precipitate, talcum powder and an anticorrosive pigment to obtain coating A; mix and grind the organosilicon-modified polyurethane B, a dispersing agent, a rheological agent, a barium sulfate precipitate, talcum powder and an anticorrosive pigment to obtain coating B; Coating A is applied to the surface of the pretreated silicon steel sheet and cured at 180-200°C for 1-2h to obtain an adhesive layer; Then apply coating B and cure it at 180-200°C for 1-2h to obtain a corrosion-resistant layer.

2. The method for preparing a rare earth metal element doped silicon steel sheet according to claim 1, characterized in that: In step 1, the silicon steel raw material includes 7-10wt% Si, 0.7-1.0wt% Cu, 0.3-0.6wt% rare earth elements, and the balance is Fe.

3. The method for preparing a rare earth metal element doped silicon steel sheet according to claim 1, characterized in that: In step 1, the rare earth element is specifically any one of Ce, La, Y, Dy, and Nd; vacuum smelting: temperature is 1400-1600°C, time is 30-40min; hot rolling processing temperature is 900-1100°C; normalizing heat treatment: temperature is 900-1000°C, time is 10-20min; high temperature heat treatment: 900-1000°C, time is 1-2h; cooling water quenching treatment: cooling to 600-650°C and then cooling to 25-30°C by water quenching; tempering heat treatment: temperature is 200-300°C, time is 0.5-1h.

4. The method for preparing a rare earth metal element doped silicon steel sheet according to claim 1, characterized in that: In step 2, the contents of the components of the organosilicon-modified polyurethane are as follows: by mass: 13-15 parts of polytetrahydrofuran, 25-30 parts of hydroxypropyl-terminated silicone oil, 0.005-0.007 parts of diisobutyltin dioctanoate, 18-25 parts of hexamethylene diisocyanate, 105-115 parts of tetrahydrofuran, 12-16 parts of modified silica solution, 14-19 parts of fluorine-containing solution and / or 18-28 parts of silanized epoxy resin solution.

5. The method for preparing a rare earth metal element doped silicon steel sheet according to claim 1, characterized in that: In step 2, the reaction mass ratio of epoxy resin, butyl acetate and 3-aminopropyltriethoxysilane is 10:1:(1.0-1.5).

6. The method for preparing a rare earth metal element doped silicon steel sheet according to claim 1, characterized in that: In step 2, the reaction mass ratio of the nano-silica filler and 3-mercaptopropyltrimethoxysilane is 2:(5-6).

7. The method for preparing a rare earth metal element doped silicon steel sheet according to claim 1, characterized in that: In step three, the content of each component of coating A is: by mass fraction, 65-75% silicone modified polyurethane A, 0.7-1.0% dispersing aid, 0.3-0.5% rheological additive, 5-7% barium sulfate precipitate, 5-7% talcum powder, and the balance is anti-corrosion pigment; the content of each component of coating B is: by mass fraction, 65-75% silicone modified polyurethane B, 0.7-1.0% dispersing aid, 0.3-0.5% rheological additive, 5-7% barium sulfate precipitate, 5-7% talcum powder, and the balance is anti-corrosion pigment.

8. The method for preparing a rare earth metal element doped silicon steel sheet according to claim 1, characterized in that: In step three, the thickness of the adhesion layer is 40-60 μm, and the thickness of the corrosion-resistant layer is 90-100 μm.

Images