Neutral salt mist resistant non-oriented silicon steel coating composition as well as preparation method and application thereof

Abstract

The invention provides a neutral salt mist resistant non-oriented silicon steel coating composition and a preparation method and application thereof. The coating composition provided by the invention comprises a corrosion inhibitor, and the corrosion inhibitor comprises a benzotriazole derivative and sodium benzoate; zinc borate; octylphenol polyoxyethylene ether; an acrylic resin; and a solvent. According to the coating composition, the benzotriazole derivative and the sodium benzoate are compounded, meanwhile, the zinc borate is added, an insulating coating can be formed on the surface of the non-oriented silicon steel, the insulating performance of the non-oriented silicon steel is guaranteed, meanwhile, the neutral salt spray corrosion resistance of the non-oriented silicon steel is improved, the corrosion speed of the non-oriented silicon steel is decreased, and the corrosion amount of the non-oriented silicon steel is reduced. Experimental results show that the interlayer resistance of the coating is 3 omega.cm < 2 > / piece or above, the non-oriented silicon steel is corroded for 10 hours under the neutral salt mist condition, the corrosion area is lower than 10%, and the neutral salt mist corrosion resistance of the non-oriented silicon steel is remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of metal treatment, and in particular to a neutral salt spray-resistant non-oriented silicon steel coating composition, a preparation method thereof and an application thereof. Background Art

[0002] With the high growth of new energy vehicle output, energy efficiency upgrades in the manufacturing industry, and quality and efficiency improvements in power grids, the rapid development of multiple industries such as electricity, metallurgy, mining, building materials, petroleum and petrochemicals, environmental protection, and water conservancy has been driven. High-end non-oriented silicon steel has gradually become one of the important materials for promoting the rapid development of modern electronics and information industries. High-end non-oriented silicon steel is a starting, excitation, compensation, and speed regulation structure for medium and large AC motors with a single power of 200 to 30,000 kilowatts, high-efficiency energy-saving motors, increased safety explosion-proof motors, variable frequency speed-regulating motors, small and medium-sized gas turbine generators, permanent magnet synchronous motors, large diesel generators and other equipment. Depending on the transportation and service environment of the equipment, it is inevitably corroded by seawater, atmosphere, rainwater, sulfides and other substances. Neutral substances will act as electrolytes, accelerating the diffusion of oxygen atoms into the non-oriented silicon steel substrate used to make the iron core to form a large amount of Si and Fe oxides, thereby causing serious corrosion and reducing the service life of the motor. Therefore, corrosion resistance requirements are put forward for the performance of silicon steel, especially resistance to neutral salt corrosion.

[0003] The prior art discloses a variety of methods for improving the corrosion resistance of non-oriented silicon steel, mainly by improving the composition of silicon steel and its preparation process. For example, the patent document with application number 202311807934.1 discloses a method for producing high-efficiency non-oriented silicon steel with good corrosion resistance, which is determined by the range of chemical composition, especially Si, Sn and Cu elements, and a reasonable production process to obtain high-efficiency non-oriented silicon steel with high magnetic induction, low iron loss and good corrosion resistance, which fundamentally improves the corrosion resistance of silicon steel. However, this method increases the complexity of the production process of non-oriented silicon steel. Summary of the invention

[0004] In view of this, the present invention provides a neutral salt spray resistant non-oriented silicon steel coating composition, a preparation method and an application thereof. The present application forms a coating on the surface of non-oriented silicon steel, which can not only form an electronic shielding system, but also slow down the corrosion rate and amount of silicon steel.

[0005] The present application provides a neutral salt spray resistant non-oriented silicon steel coating composition, comprising:

[0006] Solvents;

[0007] A corrosion inhibitor with a mass concentration of 0.2wt% to 1.5wt%, wherein the corrosion inhibitor comprises a benzotriazole derivative and sodium benzoate;

[0008] Zinc borate with a mass concentration of 1wt% to 5wt%;

[0009] A nonionic surfactant with a mass concentration of 1wt% to 5wt%;

[0010] The mass concentration of the acrylic resin is 20wt% to 30wt%.

[0011] In some specific implementations, the benzotriazole derivative is selected from at least one of 4-sulfonic acid benzotriazole, 5-methyl-4-sulfonic acid benzotriazole, 4-carboxylic acid benzotriazole and 5-carboxylic acid benzotriazole.

[0012] In some specific implementations, the mass ratio of the benzotriazole derivative to sodium benzoate is 1 to 5:1.

[0013] In some specific implementations, the nonionic surfactant is selected from at least one of alkylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, alkylolamide, polyoxyethylene nonionic surfactant and sucrose fatty acid ester.

[0014] The present application also provides a method for preparing the non-oriented silicon steel coating composition described in the above technical solution, comprising the following steps:

[0015] The corrosion inhibitor is dissolved in an organic solvent, and then mixed with zinc borate, a nonionic surfactant and an acrylic resin for reaction to obtain a non-oriented silicon steel coating composition.

[0016] In some specific implementations, the reaction is carried out under stirring conditions;

[0017] The reaction temperature is room temperature, the pressure is normal pressure, and the reaction time is 1 h to 2 h.

[0018] The present application also provides a neutral salt spray resistant non-oriented silicon steel, comprising: a non-oriented silicon steel body and a coating formed on the surface of the non-oriented silicon steel body, wherein the coating is formed by the coating composition described in the above technical solution or a coating composition prepared by the preparation method described in the above technical solution.

[0019] In some specific implementations, the coating has a thickness of 0.6 μm to 1.4 μm.

[0020] The present application provides a method for preparing neutral salt spray resistant non-oriented silicon steel, comprising the following steps:

[0021] Pre-treating the non-oriented silicon steel body;

[0022] Annealing the pre-treated non-oriented silicon steel body;

[0023] The annealed non-oriented silicon steel body is coated with the coating composition described in the above technical solution or the coating composition prepared by the preparation method described in the above technical solution, and a coating is formed on the surface of the non-oriented silicon steel body after drying.

[0024] In some specific implementations, during the coating process, a magnetic filtration device or a 100-200 mesh filter is used to filter the coating composition.

[0025] The neutral salt spray resistant non-oriented silicon steel coating composition provided in the present application includes: a solvent; a corrosion inhibitor with a mass concentration of 0.2wt% to 1.5wt%, wherein the corrosion inhibitor includes a benzotriazole derivative and sodium benzoate; a zinc borate with a mass concentration of 1wt% to 5wt%; a non-ionic surfactant with a mass concentration of 1wt% to 5wt%; and an acrylic resin with a mass concentration of 20wt% to 30wt%. The coating composition provided in the present application is compounded with benzotriazole derivatives and sodium benzoate, and zinc borate is added at the same time, which can form an insulating coating on the surface of non-oriented silicon steel, thereby ensuring the insulation performance of the non-oriented silicon steel while improving its resistance to neutral salt spray corrosion, slowing down the corrosion rate of the non-oriented silicon steel, and reducing its corrosion amount. Experimental results show that the interlayer resistance of the coating provided in the present application is 3Ω·cm 2 / piece or more, and the corrosion area of ​​non-oriented silicon steel is less than 30% after 6 hours of corrosion under neutral salt spray conditions, and even less than 10% after 10 hours of corrosion under neutral salt spray conditions, which significantly improves its neutral salt spray corrosion resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The photo of silicon steel corrosion for 2h provided in Example 4;

[0027] Figure 2 The photo of silicon steel corrosion for 4 hours provided in Example 4;

[0028] Figure 3 The photo of silicon steel corrosion for 6 hours provided in Example 4;

[0029] Figure 4 The photo of silicon steel corrosion for 8 hours provided in Example 4;

[0030] Figure 5 The photo of silicon steel corrosion for 2h provided in Comparative Example 2;

[0031] Figure 6 The photo of silicon steel corrosion for 4 hours provided in Comparative Example 2;

[0032] Figure 7 The photo of silicon steel corrosion for 6 hours provided in Comparative Example 2;

[0033] Figure 8 This is a photo of silicon steel corroded for 10 hours provided for Comparative Example 2. DETAILED DESCRIPTION

[0034] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0036] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined. In addition, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] The present application provides a neutral salt spray resistant non-oriented silicon steel coating composition, comprising:

[0038] Solvents;

[0039] A corrosion inhibitor with a mass concentration of 0.2wt% to 1.5wt%, wherein the corrosion inhibitor comprises a benzotriazole derivative and sodium benzoate;

[0040] Zinc borate with a mass concentration of 1wt% to 5wt%;

[0041] A nonionic surfactant with a mass concentration of 1wt% to 5wt%;

[0042] The mass concentration of the acrylic resin is 20wt% to 30wt%.

[0043] The coating composition provided in the present application includes a corrosion inhibitor, and the corrosion inhibitor includes a benzotriazole derivative and sodium benzoate. The two are used in combination, which can not only improve the neutral salt spray corrosion resistance of the coating, but also improve the insulation performance of the coating. In some specific implementations, the benzotriazole derivative is selected from at least one of 4-sulfonic acid benzotriazole, 5-methyl-4-sulfonic acid benzotriazole, 4-carboxylic acid benzotriazole and 5-carboxylic acid benzotriazole, preferably 4-sulfonic acid benzotriazole. In some specific implementations, the mass ratio of the benzotriazole derivative and sodium benzoate is 1 to 5: 1, preferably 2 to 4: 1, and more preferably 3: 1. In some specific implementations, the mass concentration of the corrosion inhibitor is preferably 0.5wt% to 1.4wt%.

[0044] The coating composition provided in the present application includes zinc borate, which can improve the neutral salt spray resistance of silicon steel. In some specific implementations, the mass concentration of the zinc borate is preferably 2wt% to 4wt%, more preferably 2.5wt% to 3.5wt%.

[0045] The coating composition provided in the present application includes a nonionic surfactant. In some specific implementations, the nonionic surfactant is selected from at least one of alkylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, alkylolamide, polyoxyethylene nonionic surfactant and sucrose fatty acid ester, preferably alkylphenol polyoxyethylene ether, more preferably octylphenol polyoxyethylene ether. In some specific implementations, the mass concentration of the nonionic surfactant is preferably 2wt% to 4wt%, more preferably 2.5wt% to 3.5wt%.

[0046] The coating composition provided in the present application includes an acrylic resin, which is used as a film-forming resin to form a coating under dry conditions. In some specific implementations, the mass concentration of the acrylic resin is preferably 22wt% to 28wt%, more preferably 23wt% to 27wt%.

[0047] The coating composition provided in the present application includes a solvent. The present application has no special limitation on the solvent, as long as it can dissolve the corrosion inhibitor, and can be an organic solvent, such as dimethylformamide (DMF) and the like.

[0048] In some specific implementations, the pH value of the coating composition is preferably 5.5-5.9, more preferably 5.6-5.8.

[0049] The present application also provides a method for preparing the non-oriented silicon steel coating composition described in the above technical solution, comprising the following steps:

[0050] The corrosion inhibitor is dissolved in an organic solvent, and then mixed with zinc borate, a nonionic surfactant and an acrylic resin for reaction to obtain a non-oriented silicon steel coating composition.

[0051] The present application first dissolves the corrosion inhibitor in an organic solvent, and then reacts with zinc borate, octylphenol polyoxyethylene ether and acrylic resin to form a hybrid system. In some specific implementations, the reaction is carried out under stirring; the reaction temperature is room temperature, such as 25°C, the pressure is normal pressure, such as 0.1MPa, and the time is 1h to 2h, preferably 1.5h.

[0052] The present application also provides a neutral salt spray resistant non-oriented silicon steel, comprising: a non-oriented silicon steel body and a coating formed on the surface of the non-oriented silicon steel body, wherein the coating is formed by the coating composition described in the above technical solution or the coating composition prepared by the preparation method described in the above technical solution. In some specific implementations, the thickness of the coating is 0.6 μm to 1.4 μm, preferably 0.8 μm to 1.4 μm.

[0053] The present application provides a method for preparing neutral salt spray resistant non-oriented silicon steel, comprising the following steps:

[0054] Pre-treating the non-oriented silicon steel body;

[0055] Annealing the pre-treated non-oriented silicon steel body;

[0056] The annealed non-oriented silicon steel body is coated with the coating composition described in the above technical solution or the coating composition prepared by the preparation method described in the above technical solution, and a coating is formed on the surface of the non-oriented silicon steel body after drying.

[0057] The present application uses non-oriented silicon steel as raw material, and the non-oriented silicon steel can be high-grade non-oriented silicon steel of 50W470 or above.

[0058] The present application first pre-treats the non-oriented silicon steel body to remove impurities, oil stains, etc. on the surface of the silicon steel. In some specific implementations, the pre-treatment is alkali washing, and the specific process is as follows:

[0059] First, use alkali solution spray, then electrolytic ultrasonic cleaning, and finally hot water cleaning.

[0060] In some specific implementations, the free alkalinity of the alkali solution is 20-40, the temperature is 60-85°C, and the alkali content is ≥2.7%. In some specific implementations, during electrolytic ultrasonic cleaning, the current is 2500A-3000A, the ultrasonic frequency is 20-50kHZ, and the cleaning time is 13.8s-24s; in some specific implementations, the hot water cleaning includes hot water brushing and hot water spraying in sequence, the temperature of the hot water is 60°C-85°C, the brush roller current is 18-30A during hot water brushing, and the hot water spraying is performed until the conductivity of the non-oriented silicon steel is not more than 10ms / cm.

[0061] After the pretreatment is completed, the obtained non-oriented silicon steel body is subjected to annealing treatment. Specifically, a one-stage annealing process can be adopted, so that the non-oriented silicon steel is sequentially subjected to radiation tube heating (RTF), electric heating furnace (EHF), soaking furnace (SF), cooling tube furnace (CTF), and protective gas circulation injection rapid cooling section (RJC), wherein the hydrogen content in the RTF, EHF, SF, and CTF furnaces is 0-50%, preferably 0-40%, and more preferably 0-30%; the maximum hydrogen content in the SJC furnace is 0-30%, preferably 0-20%, and more preferably 0-15%; the hydrogen content in the RJC furnace is 0-10%, and preferably 0-5%. In some specific implementations, the holding temperature of the annealing is 920°C to 980°C, preferably 930°C to 970°C, and more preferably 940°C to 960°C; the holding time of the annealing is 30s to 90s, preferably 40s to 80s, and more preferably 50s to 70s. The cooling rate after heat preservation is ≤15°C / s, preferably 5°C / s to 15°C / s, more preferably 8°C / s to 12°C / s, and the cooling time is 20s to 26s.

[0062] After annealing, the coating composition described in the above technical solution is used to coat the non-oriented silicon steel body. The present application has no special restrictions on the coating method, and roller coating is preferred. In some specific implementations, the coating amount of the roller coating is preferably 0.7 g / m 2 ~1.6g / m 2 , preferably 0.8g / m 2 ~1.5g / m 2 , more preferably 0.9 g / m 2 ~1.4g / m 2 ; The roller speed ratio is preferably 0.5-1.4:0.5-1.35, more preferably 0.7-1.3:0.7-1.3; the roller pressure is preferably 0.05kN-2.5kN, preferably 0.1kN-2kN, preferably 0.5kN-1.5kN.

[0063] In some specific implementations, during coating, it is preferred to add a magnetic filtration device or a 100-200 mesh filter in the coating liquid pan to filter out the tiny charged metal components that cannot be filtered by a 0.5 mm precision filter, so as to prevent the effective ingredients in the coating liquid from changing.

[0064] After applying the coating composition, the coating composition is dried to form a resin film to form a coating. Specifically, the drying process includes the following steps:

[0065] First, three-stage drying is performed, then three-stage sintering is performed, and finally two-stage cooling is performed.

[0066] In some specific implementations, the temperature of the three-stage drying is 610°C to 665°C, and the temperature of each stage of drying is 5°C to 15°C lower than the temperature of the previous stage of drying, preferably 10°C. In some specific implementations, the temperature of the three-stage sintering is 450°C to 490°C, and the temperature of each stage of sintering is 5°C to 15°C lower than the temperature of the previous stage of sintering, preferably 10°C. In some specific implementations, the temperature of the two-stage cooling is 400°C to 450°C.

[0067] The non-oriented silicon steel coating composition resistant to neutral salt spray provided by the present application comprises: a solvent; a corrosion inhibitor with a mass concentration of 0.2wt% to 1.5wt%, wherein the corrosion inhibitor comprises a benzotriazole derivative and sodium benzoate; a zinc borate with a mass concentration of 1wt% to 5wt%; an octylphenol polyoxyethylene ether with a mass concentration of 1wt% to 5wt%; and an acrylic resin with a mass concentration of 20wt% to 30wt%. The coating composition provided by the present application is compounded with a benzotriazole derivative and sodium benzoate, and zinc borate is added at the same time, so that an insulating coating can be formed on the surface of non-oriented silicon steel, while ensuring the insulation performance of the non-oriented silicon steel, improving its neutral salt spray corrosion resistance, delaying the corrosion rate of the non-oriented silicon steel, and reducing its corrosion amount. The experimental results show that the interlayer resistance of the coating provided by the present application is above 3Ω, and the non-oriented silicon steel is corroded under neutral salt spray conditions for 6 hours, and the corrosion area is less than 30%, and even the corrosion area is less than 10% under neutral salt spray conditions for 10 hours, which significantly improves its neutral salt spray corrosion resistance.

[0068] The following is a detailed description of a neutral salt spray resistant non-oriented silicon steel coating composition, a preparation method thereof and an application thereof provided in the present application in conjunction with embodiments.

[0069] Example 1

[0070] At 25°C and normal pressure, 4-sulfonic acid benzotriazole and sodium benzoate were added to dimethylformamide (DMF) in a mass ratio of 3:1 and stirred to dissolve. The total mass concentration of 4-sulfonic acid benzotriazole and sodium benzoate is shown in Table 1. Then, 3.5wt% of zinc borate, 2.3wt% of octylphenol polyoxyethylene ether, and 25wt% of acrylic resin were added, and the mixture was stirred for 1.5h to obtain a coating composition. The pH value of the coating composition is shown in Table 1.

[0071] Embodiments 2 to 7

[0072] (1) Alkali washing: 50W470 non-oriented silicon steel is sprayed and brushed with an alkali solution having a free alkalinity of 30, a temperature of 75°C and an alkali content of 3% at a unit speed of 80 m / min, and then electrolytically ultrasonically cleaned for 20 seconds at an alternating current of 2800A and an ultrasonic frequency of 30 kHz to fully clean the rolling oil stains, and then brushed with hot water at 75°C. During the hot water brushing, the brush roller current is 25A, and finally sprayed with hot water at 75°C to make the conductivity of the non-oriented silicon steel not greater than 10 ms / cm;

[0073] (2) Annealing: A one-stage annealing process is adopted, in which the non-oriented silicon steel is subjected to radiation tube heating (RTF), electric heating furnace (EHF), soaking furnace (SF), cooling tube furnace (CTF), and protective gas circulation injection rapid cooling section (RJC) in sequence. The hydrogen content in the RTF, EHF, SF, and CTF furnaces is 20%, the maximum hydrogen content in the SJC furnace is 20%, and the hydrogen content in the RJC furnace is 5%. The annealing soaking temperature is controlled at 960°C, the soaking time is 60s, the cooling rate is controlled at 12°C / s, and the annealing is performed for 20s.

[0074] (3) Use pre-coating liquid to pre-coat the nozzle, the pre-coating liquid formula is as follows:

[0075] Boric acid 6.8wt%, chromic anhydride 22.7wt%, magnesium oxide 1.5wt%, sodium borohydride 0.2wt%, acrylic resin 20wt%, ethylene glycol 47.4%, polydimethylsiloxane 1.3wt%, silicon dioxide 0.1wt%.

[0076] (4) A coating roller coating process is used to coat the non-oriented silicon steel obtained in step (2), which specifically comprises the following steps:

[0077] The coating composition prepared in Example 1 was used as the coating liquid, and the coating was applied by roller coating. A magnetic filtration device was added to the coating liquid pan to filter out the tiny metal components with charge accumulation that could not be filtered by the 0.5 mm precision filter, so as to prevent the effective ingredients in the coating liquid from changing; roller speed ratio: 1:1, roller pressure: 1 kN, coating amount and coating thickness see Table 1.

[0078] (5) Drying: The unit production speed is 120m / min, the drying sections (DS) 1 to 3 are 660℃, 650℃ and 640℃ respectively, the sintering sections (BS) 1 to 2 are 480℃ and 470℃ respectively, and the cooling section (AJC) is 420℃. The plate temperature is guaranteed to be no lower than 290℃, and a coating is formed after drying.

[0079] Table 1 Main process parameters of the embodiment

[0080]

[0081] Comparative Example 1

[0082] The difference from Example 4 is that no coating is formed, that is, only the steps of alkali washing and annealing are performed, and no subsequent steps are performed.

[0083] Comparative Example 2

[0084] The difference from Example 4 is that only 4-sulfonic acid benzotriazole is added to the coating composition, and sodium benzoate is not added. The other steps are the same as those of Example 4.

[0085] Comparative Example 3

[0086] The difference from Example 4 is that the coating liquid in step (4) uses a commercially available corrosion inhibitor from Quaker Houghton (RUST VETO4214HF).

[0087] Test example

[0088] Carry out the salt spray test as follows:

[0089] (1) Salt solution preparation: The salt solution should be prepared in a dissolving ratio of 5 parts sodium chloride and 95 parts water. The water should meet the requirements of Type IV in Specification D1193 (except for the restrictions on chloride ions in this specification, sodium ions can be ignored). The total impurity content of sodium chloride shall not exceed 0.3%. The content of other halogen ions (bromide ions, fluoride ions and iodide ions) except chloride ions shall be less than 0.1% (mass) of the salt content. The copper ion content shall be less than 0.3 ppm of the total amount. Sodium chloride with added anti-caking agent is not allowed to be used. The restrictions on the impurity content in sodium chloride are shown in Table 2, which shows the restrictions on the impurity content of sodium chloride.

[0090] Table 2 shows the limits of impurity content of sodium chloride

[0091] Impurities Allowable content Total impurities content ≤0.3％ Halides other than chloride (bromide, fluoride and iodide) ＜0.1％ Copper ions <0.3ppm

[0092] In addition, it is not allowed to add anti-caking agents and other substances related to ion components.

[0093] In addition, the salt solution needs to meet the following conditions:

[0094] A. To calculate the amount of salt required to make a 5% salt solution for a known mass of water, use the following general formula:

[0095] 0.053*total amount of water = required amount of NaCl

[0096] The density of water is 1g / mL. To calculate the number of grams of salt needed to prepare 1 liter of 5% saline solution, multiply 1000g by 0.053. To prepare a 5% saline solution by mass, 53g of NaCl is required per liter of water.

[0097] The multiplier 0.053 used for sodium chloride in the above formula is calculated as follows: 1000g divided by 0.95 (95% of the total mass is water) gives 1053g, which is the total mass of 1 liter of water containing 5% sodium chloride. 1053g minus the mass of the original 1 liter of water, 1000g, gives the mass of sodium chloride, which is 53 grams. The mass of sodium chloride, 53g, divided by the weight of water, 1000g, gives the coefficient of sodium chloride, 0.053.

[0098] B. To ensure that the appropriate salt solution concentration is achieved when mixing the solution, it is necessary to use a salt solution density meter or a liquid hydrometer to measure the solution. When using a salt solution density meter, the test result is 4% to 6% at 25°C (77°F).

[0099] C. If the purity of the salt used is greater than 99.9%, the halogen ion content can be ignored because the halogen ion content cannot be greater than or equal to 0.1%. If the purity of the salt is relatively low, the halogen ion content needs to be tested.

[0100] When atomized at 35°C (95°F), the pH of the collected salt solution should be between 6.5 and 7.2. The solution before atomization should be free of suspended solids. The pH test should be conducted at 23±3°C (73±5°F) using a suitable pH-sensitive glass electrode or standard electrode. The pH test system should comply with Test Method E70.

[0101] (2) Steel plate specimen: 100 mm × 150 mm;

[0102] (3) Test conditions: A sodium chloride solution prepared with distilled water having a conductivity of less than 20 μs, i.e., the above-mentioned salt solution, was used. The test chamber temperature was 35°C, the humidity was 100%, and the spraying cycle was 8 hours.

[0103] (4) Test record: The samples were taken out every 2 hours, photographed and then the test was continued until 8 hours had passed.

[0104] The results are shown in Table 3, which shows the salt spray test results of non-oriented silicon steel provided in the embodiments and comparative examples of the present application.

[0105] Table 3 Salt spray test results of non-oriented silicon steel provided by the embodiments and comparative examples

[0106]

[0107] The corrosion conditions of the silicon steel provided in Example 4 and Comparative Example 2 were observed at 2h, 4h, 6h and 8h, respectively. Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 , Figure 1 The photo of silicon steel corrosion for 2h provided in Example 4, Figure 2 The photo of silicon steel corrosion for 4 hours provided in Example 4; Figure 3 The photo of silicon steel corrosion for 6 hours provided in Example 4; Figure 4 The photo of silicon steel corrosion for 8 hours provided in Example 4; Figure 5 The photo of silicon steel corrosion for 2h provided in Comparative Example 2; Figure 6 The photo of silicon steel corrosion for 4 hours provided in Comparative Example 2; Figure 7 The photo of silicon steel corrosion for 6 hours provided in Comparative Example 2; Figure 8 The photo of silicon steel corrosion for 8h provided for comparative example 2. Figures 1 to 8 As can be seen from Table 3, the coating provided in the present application can greatly improve the neutral salt spray corrosion resistance of silicon steel.

[0108] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A neutral salt spray resistant non-oriented silicon steel coating composition, comprising: Solvents; A corrosion inhibitor with a mass concentration of 0.2wt% to 1.5wt%, wherein the corrosion inhibitor comprises a benzotriazole derivative and sodium benzoate; Zinc borate with a mass concentration of 1wt% to 5wt%; A nonionic surfactant with a mass concentration of 1wt% to 5wt%; The mass concentration of the acrylic resin is 20wt% to 30wt%.

2. The non-oriented silicon steel coating composition according to claim 1, characterized in that: The benzotriazole derivative is at least one selected from 4-sulfonic acid benzotriazole, 5-methyl-4-sulfonic acid benzotriazole, 4-carboxylic acid benzotriazole and 5-carboxylic acid benzotriazole.

3. The non-oriented silicon steel coating composition according to claim 2, characterized in that: The mass ratio of the benzotriazole derivative to sodium benzoate is 1 to 5:

1.

4. The non-oriented silicon steel coating composition according to claim 1, characterized in that: The nonionic surfactant is selected from at least one of alkylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, alkylolamide, polyoxyethylene nonionic surfactant and sucrose fatty acid ester.

5. The method for preparing the non-oriented silicon steel coating composition according to any one of claims 1 to 4, comprising the following steps: The corrosion inhibitor is dissolved in an organic solvent, and then mixed with zinc borate, a nonionic surfactant and an acrylic resin for reaction to obtain a non-oriented silicon steel coating composition.

6. The preparation method according to claim 5, characterized in that: The reaction is carried out under stirring; The reaction temperature is room temperature, the pressure is normal pressure, and the reaction time is 1 h to 2 h.

7. A neutral salt spray resistant non-oriented silicon steel comprising: A non-oriented silicon steel body and a coating formed on the surface of the non-oriented silicon steel body, wherein the coating is formed by the coating composition according to any one of claims 1 to 4 or a coating composition prepared by the preparation method according to claim 5 or 6.

8. The non-oriented silicon steel according to claim 7, characterized in that: The coating has a thickness of 0.6 μm to 1.4 μm.

9. A method for preparing non-oriented silicon steel resistant to neutral salt spray, comprising the following steps: Pre-treating the non-oriented silicon steel body; Annealing the pre-treated non-oriented silicon steel body; The annealed non-oriented silicon steel body is coated with the coating composition according to any one of claims 1 to 4 or the coating composition prepared by the preparation method according to claim 5 or 6, and a coating is formed on the surface of the non-oriented silicon steel body after drying.

10. The preparation method according to claim 9, characterized in that: During the coating process, the coating composition is filtered using a magnetic filtering device or a 100-200 mesh filter.

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