CN113337146A

CN113337146A - Auxiliary agent for silicon steel water-based inorganic insulating coating and preparation method thereof

Info

Publication number: CN113337146A
Application number: CN202110591832.5A
Authority: CN
Inventors: 伍林; 刘盈; 胡雅; 姜伟才; 赵维民; 孙世文; 祝存燕; 吴仁智
Original assignee: Wuhan Huijing New Material Technology Co ltd
Current assignee: Wuhan Huijing New Material Technology Co ltd
Priority date: 2021-05-28
Filing date: 2021-05-28
Publication date: 2021-09-03

Abstract

The invention belongs to the technical field of coatings, and particularly relates to an auxiliary agent for a silicon steel water-based inorganic insulating coating and a preparation method thereof, wherein the auxiliary agent for the silicon steel water-based inorganic insulating coating comprises the following materials in parts by mass: 10-40 parts of aluminum dihydrogen phosphate solution, 0.1-5 parts of magnesium oxide, 0.01-5 parts of thickening agent and 1-80 parts of water. The invention also provides a preparation method of the auxiliary agent, wherein magnesium oxide suspension is added into aluminum dihydrogen phosphate solution to obtain aluminum-magnesium mixed solution for later use, then thickening agent pre-sol is added into the aluminum-magnesium mixed solution at room temperature under the stirring condition to obtain the required auxiliary agent, and the inorganic material is prepared by using the auxiliary agent.

Description

Auxiliary agent for silicon steel water-based inorganic insulating coating and preparation method thereof

Technical Field

The invention belongs to the technical field of coatings, and particularly relates to an auxiliary agent for a silicon steel water-based inorganic insulating coating and a preparation method thereof.

Background

Silicon steel is a soft magnetic functional material with complex production process and high technical content, and is one of important materials required by the development of multiple fields such as energy, military industry and the like. Silicon steel is often used in the form of laminations as the core of an electric motor or generator. In order to prevent short circuit between the laminated sheets and increase eddy current loss, an insulating coating needs to be coated on the surface of the silicon steel sheet.

At present, silicon steel insulating coatings are mainly divided into three types, namely organic coatings, semi-inorganic coatings and inorganic coatings. The organic coating is formed by mixing one or more organic resins, is suitable for a low-temperature drying process, is burnt after a high-temperature drying process or an oriented silicon steel high-temperature annealing process, and greatly reduces the insulativity, the corrosion resistance, the adhesive force and the like. The semi-inorganic coating can improve the performance of the coating by adding different inorganic components on the basis of the organic coating, for example, the addition of metal chelate can improve the adhesion of the coating, and the addition of tungstate can improve the corrosion resistance of the coating, but the semi-inorganic coating is still limited by the temperature of the drying or sintering process due to the organic components. Although the inorganic coating has good heat resistance, is suitable for the existing rolling process and is the future development trend of the silicon steel insulating coating, the existing inorganic coating also has the problems of poor adhesion, poor stability and the like, and the inorganic environment-friendly insulating coating also has the problems of poor corrosion resistance compared with a chromium-containing coating and the like, so that the inorganic coating cannot replace the chromium-containing coating.

Disclosure of Invention

Aiming at the problems of poor comprehensive properties such as stability, corrosion resistance, adhesive force and the like of the inorganic insulating paint used for silicon steel in the prior art, the invention provides the assistant for the silicon steel water-based inorganic insulating paint and the preparation method thereof.

The invention provides an auxiliary agent for a silicon steel water-based inorganic insulating coating, which comprises the following materials in parts by mass: 10-40 parts of aluminum dihydrogen phosphate solution, 0.1-5 parts of magnesium oxide, 0.01-5 parts of thickening agent and 1-80 parts of water; the content of phosphorus pentoxide in the aluminum dihydrogen phosphate solution is 32-34 wt%, and the content of aluminum oxide is 7.5-8.5 wt%; the magnesium oxide is light magnesium oxide, the purity is more than 95%, and the particle size is less than 1 mu m; the thickening agent is one or a mixture of more of sodium bentonite, sodium carbonate modified bentonite, cellulose modified bentonite, calcined kaolin, hydrothermal modified kaolin, attapulgite, acid modified attapulgite and sericite.

Preferably, the assistant for the silicon steel water-based inorganic insulating paint comprises the following materials in parts by mass: 10-40 parts of aluminum dihydrogen phosphate solution, 0.1-1.2 parts of magnesium oxide, 0.05-1.2 parts of thickening agent and 3.35-52.18 parts of water.

The invention also provides a preparation method of the water-based inorganic insulating coating additive for silicon steel, which comprises the following steps:

(1) adding the thickener into water under the stirring condition of 3000-;

(2) weighing magnesium oxide, adding the magnesium oxide into the balance of water, and uniformly stirring (preferably stirring for 5min) under the stirring condition of 300-500r/min to prepare a magnesium oxide suspension with the mass fraction of the magnesium oxide of 5-15%;

(3) adding the magnesium oxide suspension into the aluminum dihydrogen phosphate solution in several times under the stirring conditions of 40-80 ℃ and 200-;

(4) under the conditions of room temperature and stirring at 800r/min and 600-.

The invention also provides the application of the silicon steel water-based inorganic insulating paint additive in the silicon steel water-based inorganic insulating paint, wherein the silicon steel water-based inorganic insulating paint mainly comprises inorganic components such as aluminum dihydrogen phosphate solution, silica sol, pigment and filler, deionized water and the like, the applicable pH value range is 2-7, and the aluminum dihydrogen phosphate solution in the original silicon steel water-based inorganic paint is equivalently replaced and uniformly stirred when in use.

When in use, the optional pigment and filler is one of calcined kaolin, copper-cobalt black, copper-chromium black, iron oxide black and titanium dioxide.

In the silicon steel water-based inorganic insulating paint additive, aluminum dihydrogen phosphate can form a net structure at high temperature, so that the adhesive force of a coating is improved, magnesium oxide in the additive can optimize the net structure formed by the coating, the adhesive force and the corrosion resistance are improved, and the thickening agent can slow down the sedimentation of pigments and fillers and improve the stability of the paint; when the coating is applied to the oriented silicon steel coating, the magnetic performance of the oriented silicon steel can be further improved due to the tension difference between the aluminum dihydrogen phosphate and the magnesium silicate bottom layer, the defects of the magnesium silicate bottom layer can be improved due to the magnesium oxide, the viscosity of the coating can be improved due to the thickening agent, the coating performance of the coating can be improved, the reaction between the aluminum dihydrogen phosphate and the silica sol in the preparation process of the coating can be avoided, the silica sol flocculation is avoided, and the stability of the coating is improved.

Through the matching and synergistic effect of the components, the assistant provided by the invention can improve the stability of the paint and improve the corrosion resistance and adhesive force of the insulating coating when being applied to the silicon steel water-based inorganic insulating paint, thereby improving the comprehensive performance of the silicon steel inorganic insulating paint.

The technical scheme of the invention has the following beneficial technical effects:

(1) the stability of the inorganic insulating coating is improved;

(2) the adhesive force and the heat resistance of the insulating coating are improved;

(3) the corrosion resistance of the insulating coating is improved;

(4) the assistant has no special requirement, has wide application range, is suitable for non-oriented silicon steel insulating paint and oriented silicon steel insulating paint, and can be used for acidic to neutral paint.

Drawings

FIG. 1 is an SEM image of the inorganic insulating coating of oriented silicon steel of comparative example 1 at 50000 times;

FIG. 2 is an SEM image of the inorganic insulating coating of oriented silicon steel of comparative example 2 at 50000 times;

FIG. 3 is an SEM image of the inorganic insulating coating of oriented silicon steel of example 1 at 50000 times.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the description is intended to be exemplary only, and is not intended to limit the scope of the present invention. Furthermore, in the following description, descriptions of well-known technologies are omitted so as to avoid unnecessarily obscuring the concepts of the present invention.

The following examples are all commercially available starting materials, unless otherwise specified, in which:

the content of phosphorus pentoxide in the aluminum dihydrogen phosphate solution is 32-34 wt%, and the content of aluminum oxide is 7.5-8.5 wt%.

The magnesium oxide is light magnesium oxide, the purity is more than 95%, and the particle size is less than 1 μm.

The silicon steel water-based inorganic insulating paint auxiliary agent prepared by the invention is suitable for silicon steel water-based inorganic insulating paint mainly comprising inorganic components such as aluminum dihydrogen phosphate solution, silica sol, pigment and filler, deionized water and the like, the applicable pH value range is 2-7, and the use method is as follows: replacing aluminum dihydrogen phosphate solution in the original silicon steel water-based inorganic coating with equal amount, and uniformly stirring. When the paint is used, the pigment and the filler are added into the auxiliary agent, the mixture is uniformly stirred under the stirring condition of 300r/min, then the mixture is added into the mixed solution of the rest components to prepare the silicon steel inorganic insulating paint, the silicon steel inorganic insulating paint is uniformly coated on the surface of a silicon steel sheet by using a roller coating, and an insulating coating is formed after the insulating paint coating section is cured or sintered in the silicon steel rolling process.

The optional pigment and filler is one of calcined kaolin, cobalt black, copper chromium black, iron oxide black or titanium dioxide.

In the preparation of the additive, the thickening agent is kept still for too short time, so that the hydration degree of the thickening agent is reduced, the additive is layered, and the improvement of the stability of the coating by the additive is weakened, so that the additive is kept still for more than 12 hours in the preparation method, and the additive is ensured not to be layered. In the preparation process of the aluminum-magnesium mixed solution, when the preparation temperature is lower than 40 ℃, magnesium oxide is difficult to react with the aluminum dihydrogen phosphate solution, the temperature needs to be raised to promote the reaction, when the preparation temperature is higher than 80 ℃, the reduction of the preparation time is limited, and the production cost is increased due to overhigh temperature. In different steps, when the stirring rotating speed is lower than the rotating speed in the technical scheme, the stirring time is prolonged, the production cost is increased, meanwhile, the effective dispersion and the sufficient contact reaction of each component also need large shearing force and sufficient mixing provided by high rotating speed, and in addition, the grinding step in the preparation method can reduce the particle size of suspended matters, so that the coating is more stable.

The aluminum dihydrogen phosphate is used as a film forming additive to form a net structure at high temperature, so that the coating has good adhesion and heat resistance, and when the aluminum dihydrogen phosphate coating is applied to the oriented silicon steel coating, the tension difference between the aluminum dihydrogen phosphate coating and the magnesium silicate bottom layer is beneficial to improving the magnetic performance of the oriented silicon steel.

The magnesium oxide can optimize a net structure formed by the coating, improve the bonding strength of the aluminum dihydrogen phosphate, improve the adhesive force and the corrosion resistance, and play a role in improving the defects of a magnesium silicate bottom layer in the oriented silicon steel coating.

The thickening agent has excellent adsorption performance and cation exchange capacity, slows down the sedimentation speed of the filler or pigment, improves the stability of the coating, can also improve the viscosity of the coating, and is convenient for construction and coating. In addition, in the coating containing the silica sol, the thickening agent can prevent aluminum dihydrogen phosphate and the silica sol from reacting in the preparation process of the coating, so that the gel speed of the silica sol is reduced, and the stability of the coating is further improved.

Example 1

An auxiliary agent for silicon steel water-based inorganic insulating paint comprises the following raw materials in parts by weight: 10 parts of aluminum dihydrogen phosphate solution, 0.1 part of magnesium oxide, 0.6 part of sodium bentonite, 0.6 part of sodium carbonate modified bentonite and 24.7 parts of deionized water.

The silicon steel water-based inorganic insulating coating additive is prepared by the following method:

(1) weighing a thickener sodium bentonite, adding the thickener sodium bentonite into deionized water under the stirring condition of 4000r/min, stirring for 20min, filtering by using a 250-mesh steel screen, preparing thickener pre-sol with the thickener mass fraction of 5%, and standing for more than 12 hours for later use.

(2) Weighing magnesium oxide, adding into deionized water, and stirring at 400r/min for 5min to obtain magnesium oxide suspension with magnesium oxide mass fraction of 12.5%.

(3) Adding the magnesium oxide suspension into the aluminum dihydrogen phosphate solution by times under the stirring condition of 60 ℃ and 400r/min, stirring until the solution is completely clear and transparent, and then cooling to room temperature to obtain an aluminum-magnesium mixed solution for later use.

(4) Adding thickener pre-sol into the aluminum-magnesium mixed solution in several times under the stirring conditions of room temperature (25 ℃, the same below) and 700r/min, increasing the rotating speed to 1000r/min after the pre-sol is completely added, continuously stirring for 15min, then adding grinding beads, increasing the rotating speed to 3000r/min, grinding for 40min, and finally filtering by using a 250-mesh steel screen to obtain the auxiliary agent for the silicon steel water-based inorganic insulating paint.

The coating was prepared as described above: the aluminum dihydrogen phosphate solution in the silicon steel aqueous chromium-free inorganic insulating coating with the modification function consisting of the aluminum dihydrogen phosphate solution, the silica sol and the copper-cobalt black is replaced by the aid in equal amount and is uniformly stirred to obtain the silicon steel aqueous inorganic insulating coating of the example 1, in addition, according to the same method, the oriented silicon steel inorganic insulating coating of the comparative example 1 is prepared under the condition that the aid is not added, and then the oriented silicon steel inorganic insulating coating of the comparative example 2 is prepared by replacing the aid with the same amount of MgO.

The inorganic insulating coating prepared in the comparative example 1 is coated on the oriented silicon steel substrate, and then the inorganic insulating coating is formed by curing and sintering, wherein a microscopic morphology graph obtained after the microscopic morphology graph is magnified by 50000 times is shown in figure 1, and the microscopic morphology graph obtained after the microscopic morphology graph is magnified by 50000 times of the coating without the aid is shown in the figure, the morphology of the coating is formed by the agglomeration and the accumulation of particles, and cracks and pores exist among the particles.

The inorganic insulating coating prepared in the comparative example 2 is coated on the oriented silicon steel substrate and then cured and sintered to form the inorganic insulating coating, the microcosmic topography image of the oriented silicon steel substrate amplified by 50000 times is shown in figure 2, and the assistant coating amplified by 50000 times can be seen, and the MgO can convert the topography characteristics of the coating from particle agglomeration and accumulation into a net-shaped structure through comparison with figure 1, and in further element analysis (the following table 1 is the element analysis result of the bottom and the net surface of the coating of the comparative example 2), although the overlooking topography of the net-shaped structure shows the characteristic of being porous, the bottom elements of the pores are consistent with the net surface, which shows that the bottom of the pores are also insulating coatings, so that the net-shaped structure is not only a plane net-shaped structure, but also a three-dimensional net-shaped structure. Therefore, the MgO can improve the network structure formed by the coating, improve the bonding strength of the coating and improve the adhesive force and the corrosion resistance.

TABLE 1

The inorganic insulating coating prepared in the comparative example 2 is coated on the oriented silicon steel substrate, and then the inorganic insulating coating is formed through curing and sintering, wherein a micro-topography image amplified by 50000 times is shown in figure 3, and through comparison with figures 1 and 2, the finding can be seen that the use of the auxiliary agent can effectively improve the morphology of the coating, the auxiliary agent can fill holes in a coating net structure, so that the coating is smoother and more compact, no obvious holes exist in a top view, and although a small amount of cracks exist, the width of the cracks is small, and the comprehensive performance of the oriented silicon steel can still be effectively improved.

Example 2

An auxiliary agent for silicon steel water-based inorganic insulating paint comprises the following raw materials in parts by weight: 40 parts of aluminum dihydrogen phosphate solution, 1.2 parts of magnesium oxide, 0.05 part of sodium carbonate modified bentonite and 21.25 parts of deionized water. The preparation of the adjuvant is the same as in example 1, except that: the mass concentration of the thickening agent pre-sol is 1.51 percent, the mass concentration of the magnesium oxide suspension is 6.25 percent, and the temperature of the step (3) is 50 ℃.

The silicon steel water-based inorganic insulating paint was prepared according to the method of example 1.

Example 3

An auxiliary agent for silicon steel water-based inorganic insulating paint comprises the following raw materials in parts by weight: 15 parts of aluminum dihydrogen phosphate solution, 0.2 part of magnesium oxide, 0.08 part of carboxymethyl cellulose modified bentonite and 5.78 parts of deionized water. The preparation of the adjuvant is the same as in example 1, except that: the mass concentration of the thickening agent pre-sol is 1.97%, the mass concentration of the magnesium oxide suspension is 10%, and the temperature of the step (3) is 40 ℃.

The silicon steel water-based inorganic insulating paint is prepared according to the method of the embodiment 1, except that the copper-cobalt black is replaced by titanium dioxide, and the rest is unchanged.

Example 4

An auxiliary agent for silicon steel water-based inorganic insulating paint comprises the following raw materials in parts by weight: 18 parts of aluminum dihydrogen phosphate solution, 0.3 part of magnesium oxide, 0.05 part of calcined kaolin, 0.05 part of hydrothermal modified kaolin and 9.9 parts of deionized water. The preparation of the adjuvant is the same as in example 1, except that: the mass concentration of the thickening agent pre-sol is 1.41 percent, the mass concentration of the magnesium oxide suspension is 9.38 percent, and the temperature of the step (3) is 60 ℃.

Example 5

An auxiliary agent for silicon steel water-based inorganic insulating paint comprises the following raw materials in parts by weight: 24 parts of aluminum dihydrogen phosphate solution, 0.5 part of magnesium oxide, 0.5 part of sodium bentonite and 14.56 parts of deionized water. The preparation of the adjuvant is the same as in example 1, except that: the mass concentration of the thickening agent pre-sol is 6.67%, the mass concentration of the magnesium oxide suspension is 6.2%, and the temperature of the step (3) is 70 ℃.

Example 6

An auxiliary agent for silicon steel water-based inorganic insulating paint comprises the following raw materials in parts by weight: 12 parts of aluminum dihydrogen phosphate solution, 0.4 part of magnesium oxide, 0.3 part of sodium carbonate modified bentonite and 10.97 parts of deionized water. The preparation of the adjuvant is the same as in example 1, except that: the mass concentration of the thickening agent pre-sol is 5.67%, the mass concentration of the magnesium oxide suspension is 6.28%, and the temperature of the step (3) is 80 ℃.

Example 7

An auxiliary agent for silicon steel water-based inorganic insulating paint comprises the following raw materials in parts by weight: 25 parts of aluminum dihydrogen phosphate solution, 0.6 part of magnesium oxide, 0.4 part of carboxymethyl cellulose modified bentonite, 0.4 part of attapulgite and 18.6 parts of deionized water. The preparation of the adjuvant is the same as in example 1, except that: the mass concentration of the thickening agent pre-sol is 6.35 percent, the mass concentration of the magnesium oxide suspension is 15 percent, and the temperature of the step (3) is 60 ℃.

Example 8

An auxiliary agent for silicon steel water-based inorganic insulating paint comprises the following raw materials in parts by weight: 15 parts of aluminum dihydrogen phosphate solution, 1 part of magnesium oxide, 0.5 part of sodium carbonate modified bentonite, 0.5 part of sericite and 23 parts of deionized water. The preparation of the adjuvant is the same as in example 1, except that: the mass concentration of the thickening agent pre-sol is 7.14 percent, the mass concentration of the magnesium oxide suspension is 9.09 percent, and the temperature of the step (3) is 60 ℃.

Example 9

An auxiliary agent for silicon steel water-based inorganic insulating paint comprises the following raw materials in parts by weight: 35 parts of aluminum dihydrogen phosphate solution, 0.7 part of magnesium oxide, 0.2 part of calcined kaolin, 0.3 part of attapulgite and 12.13 parts of deionized water. The preparation of the adjuvant is the same as in example 1, except that: the mass concentration of the thickening agent pre-sol is 10%, the mass concentration of the magnesium oxide suspension is 8.4%, and the temperature of the step (3) is 60 ℃.

Example 10

An auxiliary agent for silicon steel water-based inorganic insulating paint comprises the following raw materials in parts by weight: 38 parts of aluminum dihydrogen phosphate solution, 1.1 parts of magnesium oxide, 0.2 part of sodium bentonite, 0.2 part of sodium carbonate modified bentonite and 13.5 parts of deionized water. The preparation of the adjuvant is the same as in example 1, except that: the mass concentration of the thickening agent pre-sol is 6.78%, the mass concentration of the magnesium oxide suspension is 12.09%, and the temperature of the step (3) is 60 ℃.

Example 11

An auxiliary agent for silicon steel water-based inorganic insulating paint comprises the following raw materials in parts by weight: 40 parts of aluminum dihydrogen phosphate solution, 0.3 part of magnesium oxide, 0.2 part of sodium carbonate modified bentonite, 0.2 part of calcined kaolin and 18.3 parts of deionized water. The preparation of the adjuvant is the same as in example 1, except that: the mass concentration of the thickening agent pre-sol is 2.6 percent, the mass concentration of the magnesium oxide suspension is 8.33 percent, and the temperature of the step (3) is 60 ℃.

Example 12

An auxiliary agent for silicon steel water-based inorganic insulating paint comprises the following raw materials in parts by weight: 20 parts of aluminum dihydrogen phosphate solution, 0.2 part of magnesium oxide, 0.15 part of attapulgite, 0.15 part of acid modified attapulgite and 25.5 parts of deionized water. The preparation of the adjuvant is the same as in example 1, except that: the mass concentration of the thickening agent pre-sol is 1.29 percent, the mass concentration of the magnesium oxide suspension is 7.41 percent, and the temperature of the step (3) is 60 ℃.

A silicon steel aqueous inorganic insulating coating was prepared according to the method of example 1, except that copper cobalt black was replaced with iron oxide black, and the others were not changed.

Example 13

An auxiliary agent for silicon steel water-based inorganic insulating paint comprises the following raw materials in parts by weight: 15 parts of aluminum dihydrogen phosphate solution, 0.1 part of magnesium oxide, 0.5 part of sodium carbonate modified bentonite and 20.23 parts of deionized water. The preparation of the adjuvant is the same as in example 1, except that: the mass concentration of the thickening agent pre-sol is 2.56%, the mass concentration of the magnesium oxide suspension is 7.52%, and the temperature of the step (3) is 60 ℃.

Example 14

An auxiliary agent for silicon steel water-based inorganic insulating paint comprises the following raw materials in parts by weight: 15 parts of aluminum dihydrogen phosphate solution, 0.1 part of magnesium oxide, 0.5 part of sodium carbonate modified bentonite and 25.65 parts of deionized water. The preparation of the adjuvant is the same as in example 1, except that: the mass concentration of the thickening agent pre-sol is 2%, the mass concentration of the magnesium oxide suspension is 8%, and the temperature of the step (3) is 60 ℃.

The silicon steel water-based inorganic insulating paint was prepared according to the method of example 2.

Example 15

An auxiliary agent for silicon steel water-based inorganic insulating paint comprises the following raw materials in parts by weight: 15 parts of aluminum dihydrogen phosphate solution, 0.1 part of magnesium oxide, 0.5 part of sodium carbonate modified bentonite and 16.73 parts of deionized water. The preparation of the adjuvant is the same as in example 1, except that: the mass concentration of the thickening agent pre-sol is 3.26 percent, the mass concentration of the magnesium oxide suspension is 5 percent, and the temperature of the step (3) is 60 ℃.

Example 16

An auxiliary agent for silicon steel water-based inorganic insulating paint comprises the following raw materials in parts by weight: 38 parts of aluminum dihydrogen phosphate, 0.4 part of magnesium oxide, 0.5 part of sodium carbonate modified bentonite and 52.18 parts of deionized water. The preparation of the adjuvant is the same as in example 1, except that: the mass concentration of the thickening agent pre-sol is 1 percent, the mass concentration of the magnesium oxide suspension is 12.99 percent, and the temperature of the step (3) is 60 ℃.

Example 17

An auxiliary agent for silicon steel water-based inorganic insulating paint comprises the following raw materials in parts by weight: 10 parts of aluminum dihydrogen phosphate, 0.1 part of magnesium oxide, 0.05 part of sodium bentonite and 3.35 parts of deionized water. The preparation of the adjuvant is the same as in example 1, except that: the mass concentration of the thickening agent pre-sol is 2.44%, the mass concentration of the magnesium oxide suspension is 6.9%, and the temperature of the step (3) is 60 ℃.

A silicon steel aqueous inorganic insulating coating was prepared according to the method of example 1, except that copper cobalt black was replaced with calcined kaolin, and the others were unchanged.

The coating obtained in each example is filled into a plastic or glass container, the container is sealed and then placed into a constant-temperature drying oven at 50 +/-2 ℃, the container is taken out in a period of 12 hours, the time for the coating to completely lose fluidity is observed and recorded, and the longer the time is, the better the stability of the coating is.

According to GB/T10125-2012 salt spray test for artificial atmosphere corrosion test, the corrosion resistance of the coated silicon steel is detected, and the result is shown in Table 2. The detection result shows that the corrosion area of the obtained chromium-free insulating coating is less than 5 percent after 8 hours of testing under the conditions of 5 percent NaCl aqueous solution and periodic spraying at 35 +/-0.5 ℃.

The adhesion and insulation performance of the obtained inorganic insulating paint are tested according to GB/T2522-2017 test method for insulation resistance and adhesion of electrical steel strip (sheet) coating, and the results are shown in Table 2. The detection result shows that the chromium-free insulating coating prepared by using the auxiliary agent has good bonding force and excellent insulating property with silicon steel.

TABLE 2 coating Performance test results

Note: the stabilization time is the time taken for the paint to completely lose fluidity recorded in the storage stability observation experiment, and the corrosion area is the area measured after 8 hours of the periodic salt spray.

It is to be understood that the above-described embodiments of the present invention are merely illustrative of or explaining the principles of the invention and are not to be construed as limiting the invention. Therefore, any modification, equivalent replacement, improvement and the like made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. Further, it is intended that the appended claims cover all such variations and modifications as fall within the scope and boundaries of the appended claims or the equivalents of such scope and boundaries.

Claims

1. An auxiliary agent for silicon steel water-based inorganic insulating paint is characterized in that: the material comprises the following materials in parts by mass: 10-40 parts of aluminum dihydrogen phosphate solution, 0.1-5 parts of magnesium oxide, 0.01-5 parts of thickening agent and 1-80 parts of water; the content of phosphorus pentoxide in the aluminum dihydrogen phosphate solution is 32-34%, and the content of aluminum oxide is 7.5-8.5%; the magnesium oxide is light magnesium oxide, the purity is more than 95%, and the particle size is less than 1 mu m; the thickening agent is one or a mixture of more of sodium bentonite, sodium carbonate modified bentonite, cellulose modified bentonite, calcined kaolin, hydrothermal modified kaolin, attapulgite, acid modified attapulgite and sericite.

2. The additive for the silicon steel aqueous inorganic insulating paint according to claim 1, wherein: the auxiliary agent comprises the following materials in parts by mass: 10-40 parts of aluminum dihydrogen phosphate solution, 0.1-1.2 parts of magnesium oxide, 0.05-1.2 parts of thickening agent and 3.35-52.18 parts of deionized water.

3. A method for preparing the assistant for the silicon steel water-based inorganic insulating paint according to any one of claims 1 to 2, which is characterized in that: the preparation method comprises the following steps:

(1) adding the thickening agent into water under the stirring condition of 3000 plus 5000r/min, uniformly stirring, filtering, preparing thickening agent pre-sol with the mass fraction of the thickening agent of 1-10%, and standing for more than 12 hours for later use;

(2) weighing magnesium oxide, adding the magnesium oxide into the balance of water, and uniformly stirring under the stirring condition of 300-500r/min to prepare a magnesium oxide suspension with the mass fraction of the magnesium oxide of 5-15%;

(3) adding the magnesium oxide suspension liquid obtained in the step (2) into the aluminum dihydrogen phosphate solution in several times under the stirring conditions of 40-80 ℃ and 200-500r/min, stirring until the solution is completely clear and transparent, and cooling to room temperature to obtain an aluminum-magnesium mixed solution for later use;

(4) and (2) adding the thickener pre-sol in the step (1) into the aluminum-magnesium mixed solution in several times under the stirring conditions of room temperature and 800r/min, increasing the rotating speed to 1200r/min after the pre-sol is completely added, continuing stirring for 5-15min, adding grinding beads, increasing the rotating speed to 3000r/min, grinding for 10-60min, and finally filtering to obtain the auxiliary agent for the silicon steel water-based inorganic insulating coating.

4. Use of the auxiliary of any one of claims 1-2 for aqueous inorganic insulating coating for silicon steel in aqueous inorganic insulating coating for silicon steel.

5. Use according to claim 4, characterized in that: the silicon steel water-based inorganic insulating paint mainly comprises inorganic components such as aluminum dihydrogen phosphate solution, silica sol, pigment and filler, deionized water and the like, wherein the pH value application range of the auxiliary agent when the auxiliary agent is applied to the silicon steel water-based inorganic insulating paint is 2-7, and the aluminum dihydrogen phosphate solution in the silicon steel water-based inorganic insulating paint is equivalently replaced and uniformly stirred when the auxiliary agent is used.