Light-adhesion thermally conductive coating for silicon steel, silicon steel sheet, and manufacturing method therefor

Abstract

A light-adhesion thermally conductive coating for silicon steel, comprising active components dispersed in water, the active components comprising: 10-30 parts by mass of an organic epoxy resin and a curing agent; 45-75 parts by mass of a metal phosphate, the metal phosphate at least comprising a zinc-containing phosphate; 5-20 parts by mass of a modified thermally conductive filler; and 2-10 parts by mass of a metal oxide. Further disclosed is a silicon steel sheet, comprising a silicon steel substrate and a thermally conductive coating on a surface of the silicon steel substrate, wherein the thermally conductive coating is obtained by coating the light-adhesion thermally conductive coating on the surface of the silicon steel substrate.

Description

A lightweight, thermally conductive coating for silicon steel, a silicon steel sheet, and a method for manufacturing the same. Technical Field

[0001] This invention relates to a coating, a steel plate, and a method for manufacturing the same, and more particularly to a coating for silicon steel, silicon steel, and a method for preparing the same. Background Technology

[0002] Silicon steel, as an important soft magnetic material, is widely used in electromagnetic equipment such as transformers and motors.

[0003] During equipment operation, silicon steel generates a significant amount of heat due to hysteresis and eddy current losses. Long-term accumulation of this heat can lead to equipment malfunctions, severely impacting its lifespan and reliability. Therefore, developing efficient heat dissipation solutions is crucial for ensuring the stable operation of silicon steel equipment, and coating the surface of silicon steel with a thermally conductive coating has become an effective heat dissipation method.

[0004] In the prior art, existing patent literature covers the above-mentioned fields:

[0005] For example, Chinese patent document CN115109514A, published on September 27, 2022, entitled "A High Thermal Conductivity Coating, Preparation Method and Application," discloses a high thermal conductivity coating, its preparation method and application. It describes a process of mixing graphene, modified high thermal conductivity powder, high thermal conductivity whiskers, organosilicon resin, organic solvent, dispersant, and curing agent, dispersing the mixture, and then preparing a high-temperature resistant, high thermal conductivity coating. The high thermal conductivity coating is then sprayed onto the surface of the component to be coated using a pressure spraying process. The component coated with the high thermal conductivity coating is then placed at a temperature of 150-300℃ for 30-60 minutes to cure, resulting in a high thermal conductivity coating layer.

[0006] For example, Chinese patent document CN106519757A, published on March 22, 2017, entitled "A Thermally Conductive Coating for Heat Dissipation of Electronic Devices," discloses a thermally conductive coating for heat dissipation of electronic devices. It adopts a reasonable formula design, which makes the composite coating have excellent adhesion and film hardness. After being coated on the surface of electronic components, it not only dissipates heat efficiently, but also helps to dissipate the heat generated by electronic components in a timely and efficient manner, thereby increasing the heat dissipation rate and improving the heat dissipation and cooling effect, resulting in excellent overall performance.

[0007] For example, Chinese patent document CN111647354A, published on September 11, 2020, entitled "A Waterproof Thermal Conductive Coating and a Method for Preparing a Waterproof Thermal Conductive Coating", discloses a method for preparing a waterproof thermal conductive coating and a waterproof thermal conductive coating. It adopts a combination of "adhesive" and "powder" in the preparation method. Fluorinated resin is selected as the adhesive to bind nano-sized hydrophobic silica and few-layer boron nitride. The nano-sized hydrophobic silica serves as the hydrophobic powder, generating a nano-rough structure on the surface of the coating. The few-layer boron nitride serves as the reinforcing phase to enhance the thermal conductivity.

[0008] The thermally conductive coatings disclosed in the aforementioned patent documents are mostly used in electronic components, and the prepared thermally conductive coatings are solvent-based coatings, which are not suitable for water-based coatings in the silicon steel field. Most thermally conductive fillers have poor dispersibility in aqueous solutions. Furthermore, since silicon steel sheets need to be subsequently laminated into iron cores, the air layers between the silicon steel sheets will greatly reduce the heat transfer effect of the thermally conductive coating.

[0009] To achieve efficient heat dissipation, thermally conductive fillers can be added to the C-3 self-adhesive coating. After curing, the self-adhesive coating can effectively isolate the air layer between the silicon steel sheets in the iron core, and the thermally conductive fillers can form an efficient heat conduction network. However, compared with the existing C-5 coating, the self-adhesive coating has a series of problems: the self-adhesive coating is expensive, resulting in high usage costs; the coating thickness is large, which easily causes adhesive overflow and reduces the stacking factor; the main component of the self-adhesive coating is organic resin, which has poor heat resistance and weldability. Summary of the Invention

[0010] One objective of this invention is to provide a lightweight, adhesive thermally conductive coating for silicon steel. This coating can be applied to the surface of a silicon steel substrate to form a coating layer. In addition to the excellent properties of conventional C-5 type coatings, this coating also possesses the inter-layer bonding effect of C-3 type self-adhesive coatings, as well as excellent thermal conductivity. Furthermore, after a secondary hot-pressing process, the problems of poor thermal conductivity, low fixing strength, and vibration noise in the iron core can be effectively improved.

[0011] To achieve the above objectives, the present invention provides a lightweight, viscous, thermally conductive coating for silicon steel, comprising an effective component dispersed in water, wherein the effective component comprises, based on 100 parts by weight:

[0012] 10-30 parts by weight of organic epoxy resin and its curing agent;

[0013] 45-75 parts by weight of metal phosphates, wherein the metal phosphates include at least zinc-containing phosphates;

[0014] 5-20 parts by weight of modified thermally conductive filler;

[0015] 2-10 parts by mass of metal oxides.

[0016] Preferably, in the lightweight viscous thermally conductive coating of the present invention, the effective component, based on 100 parts by weight, comprises the following components:

[0017] 10-30 parts by weight of organic epoxy resin and its curing agent;

[0018] 45-75 parts by weight of metal phosphates, wherein the metal phosphates include at least zinc-containing phosphates;

[0019] 5-20 parts by weight of modified thermally conductive filler;

[0020] 2-10 parts by mass of metal oxides.

[0021] In this invention, the organic epoxy resin and its curing agent initiate a crosslinking process through chemical reactions between functional groups, releasing heat and forming primary crosslinking points. As the reaction proceeds, the resin molecular chains form a three-dimensional network crosslinked structure through the bridging effect of the curing agent. This structure significantly improves the mechanical strength of the coating while providing strong interfacial adhesion to the silicon steel sheets, inhibiting interlayer slippage. Before curing, the liquid resin can fully wet the micro-uneven structure of the silicon steel surface, and the volume shrinkage rate is low during curing, forming a continuous and dense adhesive layer. This layer, through the dual effects of physical interlocking and chemical bonding, tightly adheres adjacent silicon steel sheets, effectively replacing the air layer with poor thermal conductivity (the thermal conductivity of air is approximately 0.02 W / (m·K)). The crosslinked resin matrix forms thermally conductive channels through the orderly arrangement of molecular chain segments. This continuous phase structure significantly shortens the heat conduction path and reduces interfacial thermal resistance.

[0022] In this invention, metal phosphates can ensure that the coating has good heat resistance, corrosion resistance, and adhesion.

[0023] In this invention, the modified thermally conductive filler reduces its surface energy and enhances its compatibility with the resin by covering the polar sites on the surface of the thermally conductive filler, thereby reducing agglomeration. At the same time, the two ends of the modifier molecule are respectively combined with the filler and the resin to form "molecular bridges" and improve the interfacial bonding force. In addition, the long-chain modifier can also prevent the filler from agglomerating through the steric hindrance effect, so that the filler is uniformly dispersed in the coating, significantly improving the mixing stability and thermal conductivity.

[0024] In this invention, the metal oxide can be further combined with thermally conductive fillers to form a thermally conductive network, while enhancing the insulation and scratch resistance of the coating.

[0025] It should be noted that the term "lightly adhesive coating" refers to steel sheets prepared with this type of coating that have adhesive properties, but the bond strength is lower than that of coatings formed by self-adhesive coatings. The bond strength of steel sheets prepared with lightly adhesive coatings is typically 2.0-3.5 N / mm (DIN EN 1464 standard), which is lower than that of ordinary C-3 type self-adhesive coatings (bond strength > 3.5 N / mm).

[0026] Preferably, in the lightweight viscous thermally conductive coating of the present invention, the effective ingredient further comprises 1-8 parts by weight of an additive, based on 100 parts by weight of the effective ingredient.

[0027] In this invention, the main function of the additives is to increase the mutual solubility of the above-mentioned coating components, and at the same time, to reduce the surface tension of the solution and prevent defects such as pinholes and missed coatings from occurring in the coating during the baking process.

[0028] Preferably, in the lightweight viscous thermally conductive coating of the present invention, the additives include at least two of ethylene glycol, glycerol, n-butanol, isobutanol, isopropanol, ethylene glycol methyl ether, ethylene glycol butyl ether, propylene glycol methyl ether, propylene glycol butyl ether, and propylene glycol methyl ether acetate.

[0029] Preferably, in the lightweight viscous thermally conductive coating of the present invention, the organic epoxy resin includes at least one of bisphenol A type epoxy resin, alicyclic epoxy resin, biphenyl type epoxy resin, and phenolic epoxy resin; the curing agent includes at least one of dicyandiamide, amino resin, imidazole, and polyisocyanate.

[0030] Preferably, in the lightweight viscous thermally conductive coating of the present invention, the content ratio of curing agent to organic epoxy resin by mass is 0.1-0.4.

[0031] Preferably, in the lightweight viscous thermally conductive coating of the present invention, the organic epoxy resin has an epoxy value of 0.40-0.90 eq / 100g and a molecular weight of 300-800.

[0032] Preferably, in the lightweight viscous thermally conductive coating of the present invention, the average particle size of the organic epoxy resin satisfies D 50 ≤2μm, D 90 ≤5μm.

[0033] In this invention, D 50 This indicates that 50% of the particle size is within the measured size range, D 90 This indicates that 90% of the particle size is within the range of the measured size values.

[0034] Preferably, in the lightweight viscous thermally conductive coating of the present invention, the metal phosphate further includes at least one phosphate containing aluminum, calcium, manganese or magnesium.

[0035] Preferably, in the lightweight, viscous thermally conductive coating of the present invention, the zinc-containing phosphate accounts for 50-75 wt% of the total amount of all metal phosphates.

[0036] Preferably, in the lightweight viscous thermally conductive coating of the present invention, the average particle size of the metal phosphate is 80-300 nm; preferably, the Zeta potential of the metal phosphate is +20 mV to -20 mV.

[0037] Preferably, in the lightweight viscous thermally conductive coating of the present invention, the agglomeration index of the metal phosphate is ≤1.8 (tested by a laser particle size analyzer).

[0038] Preferably, in the lightweight viscous thermally conductive coating of the present invention, the modified thermally conductive filler is selected from at least one of modified alumina, modified aluminum nitride, modified boron nitride, modified silicon nitride, and modified silicon carbide; and / or the particle size of the modified thermally conductive filler is 20-100 nm.

[0039] Modifying thermally conductive fillers is within the scope of conventional knowledge for those skilled in the art, and any suitable coupling agent can be used to modify the thermally conductive fillers using methods known in the art. However, preferably, in the lightweight viscous thermally conductive coating of the present invention, the modifier of the modified thermally conductive filler can be one or more of titanate coupling agents or silane coupling agents.

[0040] Preferably, the silane coupling agent is one or more of KH-560, KH570, and A171.

[0041] Preferably, in the lightweight viscous thermally conductive coating of the present invention, the metal oxide is selected from at least one of SiO2, TiO2, ZnO, ZrO2, and Fe3O4; preferably, the particle size of the metal oxide is 100-300 nm.

[0042] Preferably, in the light-viscosity thermally conductive coating of the present invention, the solid content is 25-50 wt%; preferably, the viscosity of QND-4 is 15-40 s.

[0043] In this invention, by controlling the viscosity of QND-4, better precise control of coating thickness and high-speed roll coating performance can be achieved.

[0044] To achieve the above objectives, the present invention provides a silicon steel sheet comprising a silicon steel substrate and a thermally conductive coating on the surface of the silicon steel substrate, wherein the thermally conductive coating is obtained by coating the surface of the silicon steel substrate with the aforementioned lightweight, viscous thermally conductive coating.

[0045] Preferably, in the silicon steel plate of the present invention, the single-sided dry film thickness of the thermally conductive coating is 0.5-2 μm.

[0046] Preferably, in the silicon steel plate of the present invention, the thermal conductivity of the silicon steel plate is ≥3W / (m·K).

[0047] Preferably, in the silicon steel sheet of the present invention, the bonding strength of the silicon steel sheet is ≥2N / mm (DIN EN 1464 bonding strength test standard).

[0048] Compared with existing technologies, the lightweight, viscous thermally conductive coating for silicon steel, the silicon steel plate, and the manufacturing method thereof described in this invention have the following beneficial effects:

[0049] The lightweight, viscous thermally conductive coating for silicon steel described in this invention uses a water-based epoxy resin emulsion system, which is free of volatile organic solvents (VOCs). It releases no irritating odors during production and use. The metal phosphates are mainly light metals such as zinc and aluminum, and do not contain toxic heavy metals such as lead and chromium, thus reducing the risk of environmental pollution. The coating and the silicon steel substrate form an integrated structure through chemical bonding, which does not affect the recycling of silicon steel sheets and conforms to the concepts of green manufacturing and circular economy.

[0050] The lightweight, thermally conductive coating for silicon steel described in this invention, while possessing the excellent properties of conventional C-5 type coatings, also exhibits the bonding effect of C-3 self-adhesive coatings, with a bonding strength exceeding 2 N / mm. This results in an overall strengthening of the iron core structure, effectively improving issues such as low core fixing strength, low natural frequency, and high vibration and noise, thereby enabling the manufacture of motors with higher efficiency and lower vibration and noise. Furthermore, the organic epoxy resin emulsion penetrates the microstructure of the silicon steel surface, and combined with the chemical barrier effect of metal phosphates, achieves synergistic optimization of corrosion resistance and mechanical properties. This avoids the problems of poor heat resistance, poor weldability, low stacking coefficient, and hot-pressing overflow associated with C-3 type self-adhesive coatings.

[0051] The lightweight, viscous thermally conductive coating for silicon steel described in this invention constructs a thermally conductive network using metal phosphates and nano-thermal conductive fillers, achieving a thermal conductivity of over 3 W / (m·K), which is more than 15 times higher than that of traditional silicon steel resin coatings. The organic epoxy resin emulsion forms continuous cross-linked channels after curing, significantly reducing interfacial thermal resistance and maintaining stable thermal conductivity at high temperatures, effectively solving the heat dissipation problems of motors and transformers.

[0052] The lightweight, viscous thermally conductive coating for silicon steel described in this invention can be applied to the substrate surface of silicon steel plates used in the cores of various electric motors and generators, and can form a coating on the substrate. It is particularly suitable for non-oriented silicon steel materials used in new growth fields such as electric motors for new energy vehicles, servo motors, and micro motors. The ultra-thin coating is compatible with high-speed roller coating processes, has low material costs, and combines the advantages of efficient heat dissipation and large-scale production, with huge market potential. Attached Figure Description

[0053] Figure 1 schematically illustrates the relationship between the organic epoxy resin content and the coating adhesion strength in the lightweight, viscous thermally conductive coating for silicon steel described in this invention.

[0054] Figure 2 schematically shows the relationship between the content of modified thermally conductive filler and the thermal conductivity in the lightweight, viscous thermally conductive coating for silicon steel described in this invention. Detailed Implementation

[0055] The following will further explain and illustrate the lightweight, viscous thermally conductive coating for silicon steel, the silicon steel plate, and the manufacturing method thereof according to the present invention with reference to specific embodiments. However, such explanation and illustration do not constitute an undue limitation on the technical solution of the present invention.

[0056] Examples 1-10 and Comparative Examples 1-4

[0057] Prepare a lightweight, viscous thermally conductive coating for silicon steel according to the following steps:

[0058] (1) Prepare an effective component masterbatch, which, based on 100 parts by weight, contains 10-30 parts by weight of organic epoxy resin and its curing agent; 45-75 parts by weight of metal phosphate, which includes at least zinc-containing phosphate; 5-20 parts by weight of modified thermally conductive filler; and 2-10 parts by weight of metal oxide.

[0059] In some embodiments, the masterbatch may also contain 1-8 parts by weight of an additive. In some more specific embodiments, the additive includes any two or more of the following substances: ethylene glycol, glycerol, n-butanol, isobutanol, isopropanol, ethylene glycol methyl ether, ethylene glycol butyl ether, propylene glycol methyl ether, propylene glycol butyl ether, and propylene glycol methyl ether acetate.

[0060] In some specific embodiments, the organic epoxy resin may be one or more selected from bisphenol A type epoxy resin, alicyclic epoxy resin, biphenyl type epoxy resin, and phenolic epoxy resin. The curing agent may be one or more selected from dicyandiamide, amino resin, imidazole, and polyisocyanate.

[0061] In some specific embodiments, the epoxy value of the organic epoxy resin can be 0.40-0.90 eq / 100g, and the molecular weight can be 300-800.

[0062] In some specific implementations, the ratio of curing agent to organic epoxy resin can be 0.1-0.4.

[0063] In some specific embodiments, the average particle size of the organic epoxy resin satisfies D 50 ≤2μm, D 90 ≤5μm.

[0064] In some specific embodiments, zinc phosphate accounts for 50-75 wt% of the total amount of all metal phosphates. In some specific embodiments, zinc-containing phosphate can be prepared by dissolving zinc sulfate and ammonium dihydrogen phosphate in deionized water at a molar ratio of 1:2, adding 1-2% polyvinyl alcohol as a dispersant, stirring at room temperature for 30 min, and filtering.

[0065] In addition, metal phosphates may include at least one phosphate containing aluminum, zinc, calcium, manganese or magnesium.

[0066] In some specific implementations, the average particle size of the metal phosphate can be 80-300 nm, the agglomeration index ≤1.8 (measured by a laser particle size analyzer), and the zeta potential can be +20 mV to -20 mV.

[0067] In some specific embodiments, the modified thermally conductive filler can be one or more of the following: modified alumina, aluminum nitride, boron nitride, silicon nitride, and silicon carbide. The particle size of the modified thermally conductive filler can be between 20-100 nm, and the modifier can be one or more of the following: titanate coupling agents, silane coupling agents such as KH-560, KH570, and A171.

[0068] In some specific embodiments, the metal oxide can be any one or more of the following substances: SiO2, TiO2, ZnO, ZrO2, Fe3O4.

[0069] In some specific implementations, the particle size of the metal oxide can be 100-300 nm.

[0070] (2) Mix the above components and add an appropriate amount of water. Stir at 300-800 rpm for 45-90 min to finally obtain the light viscous thermal conductive coating of the present invention.

[0071] In some embodiments, the solid content of the lightweight thermally conductive coating is 25-50 wt%, and the viscosity of QND-4 is controlled at 15-40 s, so as to achieve better precise control of coating thickness and high-speed roller coating workability.

[0072] Tables 1-1, 1-2, and 1-3 list the types and mass fractions of each active ingredient in the lightweight, viscous thermally conductive coatings used in Examples 1-10 of the present invention and the comparative coatings used in Comparative Examples 1-4.

[0073] Table 1-1.

[0074] Table 1-2.

[0075] Table 1-3.

[0076] Table 2 lists the specific preparation parameters of the lightweight, viscous thermally conductive coatings used in Examples 1-10 of the present invention and the comparative coatings used in Comparative Examples 1-4.

[0077] Table 2.

[0078] The viscosity of QND-4 was determined according to GB / T 1723-1993.

[0079] Solid content was determined according to GB / T 1725-2007.

[0080] The lightweight, viscous thermally conductive coatings used in Examples 1-10 and the comparative coatings prepared in Comparative Examples 1-4 were applied to silicon steel substrates with a thickness of 0.10-0.50 mm. The substrates were then subjected to a baking process at 150-280°C for 0.5-4 minutes to obtain silicon steel sheets with a thermally conductive coating. The single-sided dry film thickness of the thermally conductive silicon steel sheets obtained in each example and comparative example was tested according to GB / T 22462-2008.

[0081] The thermal conductivity of the thermally conductive silicon steel obtained in each embodiment and comparative example was tested according to GB / T 22588-2008, and the bond strength was tested according to the DIN EN 1464 bond strength test standard. Table 3 lists the performance parameters of the silicon steel sheets of each embodiment and comparative example.

[0082] Table 3.

[0083] Furthermore, Figure 1 schematically illustrates the relationship between the organic epoxy resin content and the coating adhesion strength in the lightweight, viscous thermally conductive coating for silicon steel described in this invention.

[0084] As can be seen from Table 3 and Figure 1 above, the content of organic epoxy resin affects the main properties of the coating. Comparative Example 1 does not meet the content of organic epoxy resin specified in this invention, so its bonding strength is poor.

[0085] As can be seen from Figure 1, the bonding strength is the highest when the mass fraction of organic epoxy resin is 25 parts, reaching 3.33 N / mm.

[0086] Figure 2 schematically shows the relationship between the content of modified thermally conductive filler and the thermal conductivity in the lightweight, viscous thermally conductive coating for silicon steel described in this invention.

[0087] As can be seen from Table 3 and Figure 2 above, the content of modified thermally conductive filler has a direct impact on the thermal conductivity of the coating. When the content of modified thermally conductive filler is 12 parts by mass, the thermal conductivity of the coating is optimal, with a thermal conductivity coefficient of 3.87 W / (m·K). However, when the filler content is too low, as shown in Comparative Example 3, the thermal conductivity of the coating is poor.

[0088] In addition, the present invention also conducted performance tests on the coatings of some embodiments and comparative examples, including insulation, dispersibility, heat resistance, and weldability, and the test results are listed in Table 4. The evaluation symbols "◎" represent excellent; "⊙" represents good; "○" represents average; "△" represents deviation; and "×" represents poor and unacceptable. The specific test methods are as follows:

[0089] (1) Insulation test: The insulation of silicon steel sheets was determined according to GB / T 2522-2017 "Test method for insulation resistance and adhesion of coatings on electrical steel sheets (strips)".

[0090] (2) Dispersion test: The dispersion of the coating was tested using a laser particle size analyzer.

[0091] (3) Heat resistance test: The heat resistance of the coating was determined according to the method in GB / T 1735-2009 "Determination of heat resistance of paints and varnishes".

[0092] (4) Weldability test: The weldability of the coating was determined according to the method in GB / T 19869.1-2019 "Metallic materials welding procedure specification and qualification part 1: Welding procedure qualification of steel".

[0093] Table 4.

[0094] As can be seen from Table 4 above, the metal phosphate content of Comparative Example 2 is too low, resulting in poor heat resistance and weldability. The viscosity of QND-4 in Comparative Example 4 is too high, and no metal oxides were added, resulting in poor dispersibility.

[0095] Furthermore, Table 4 also shows that the content of metal oxides and modified thermally conductive fillers has a certain impact on the insulation of the coating. When the content of modified thermally conductive fillers or metal oxides is too low, for example, the content of modified thermally conductive fillers in Comparative Example 3 is too low, and no metal oxides are added in Comparative Example 4, the insulation of the coating is poor.

[0096] It should be noted that the combination of the technical features in this case is not limited to the combination methods described in the claims of this case or the combination methods described in the specific embodiments. All technical features described in this case can be freely combined or combined in any way, unless they contradict each other.

[0097] It should also be noted that the embodiments listed above are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made thereto are those that can be directly derived or easily conceived by those skilled in the art from the content disclosed in the present invention, and should all fall within the protection scope of the present invention.

Claims

1. A thermally conductive coating for silicon steel, characterized in that, The thermally conductive coating contains an effective ingredient dispersed in water. Based on 100 parts by weight of the effective ingredient, the effective ingredient comprises: 10-30 parts by weight of organic epoxy resin and its curing agent; 45-75 parts by weight of metal phosphates, wherein the metal phosphates include at least zinc-containing phosphates; 5-20 parts by weight of modified thermally conductive filler; 2-10 parts by mass of metal oxides.

2. The thermally conductive coating as described in claim 1, characterized in that, Based on 100 parts by weight of the active ingredient, the active ingredient is composed of the following components: 10-30 parts by weight of organic epoxy resin and its curing agent; 45-75 parts by weight of metal phosphates, wherein the metal phosphates include at least zinc-containing phosphates; 5-20 parts by weight of modified thermally conductive filler; 2-10 parts by mass of metal oxides.

3. The thermally conductive coating as described in claim 1 or 2, characterized in that, Based on 100 parts by weight of the active ingredient, the active ingredient further comprises 1-8 parts by weight of an adjuvant.

4. The thermally conductive coating as described in claim 3, characterized in that, The adjuvant includes at least two of the following: ethylene glycol, glycerol, n-butanol, isobutanol, isopropanol, ethylene glycol methyl ether, ethylene glycol butyl ether, propylene glycol methyl ether, propylene glycol butyl ether, and propylene glycol methyl ether acetate.

5. The thermally conductive coating as described in claim 1 or 2, characterized in that, The organic epoxy resin includes at least one of bisphenol A type epoxy resin, alicyclic epoxy resin, biphenyl type epoxy resin, and phenolic epoxy resin; the curing agent includes at least one of dicyandiamide, amino resin, imidazole, and polyisocyanate.

6. The thermally conductive coating as described in claim 1 or 2, characterized in that, The content ratio of curing agent to organic epoxy resin by weight is 0.1-0.

4.

7. The thermally conductive coating as described in claim 1 or 2, characterized in that, The epoxy value of organic epoxy resin is 0.40-0.90 eq / 100g, and the molecular weight is 300-800.

8. The thermally conductive coating as described in claim 1 or 2, characterized in that, The average particle size of the organic epoxy resin satisfies D 50 ≤2μm, D 90 ≤5μm.

9. The thermally conductive coating as described in claim 1 or 2, characterized in that, The metal phosphates also include at least one phosphate containing aluminum, calcium, manganese or magnesium.

10. The thermally conductive coating as described in claim 1 or 2, characterized in that, The zinc-containing phosphates comprise 50-75 wt% of the total amount of all metal phosphates.

11. The thermally conductive coating as described in claim 1 or 2, characterized in that, The average particle size of the metal phosphate is 80-300 nm; preferably, the zeta potential of the metal phosphate is +20 mV to -20 mV.

12. The thermally conductive coating as described in claim 1 or 2, characterized in that, The metal phosphate has an agglomeration index ≤1.8 as measured by a laser particle size analyzer.

13. The thermally conductive coating as described in claim 1 or 2, characterized in that, The modified thermally conductive filler is selected from at least one of modified alumina, modified aluminum nitride, modified boron nitride, modified silicon nitride, and modified silicon carbide; and / or the particle size of the modified thermally conductive filler is 20-100 nm.

14. The thermally conductive coating as described in claim 13, characterized in that, The modifier of the modified thermally conductive filler is one or more of titanate coupling agents or silane coupling agents; preferably, the silane coupling agent is one or more of KH-560, KH570, and A171.

15. The thermally conductive coating as described in claim 1 or 2, characterized in that, The metal oxide is selected from at least one of SiO2, TiO2, ZnO, ZrO2, and Fe3O4; preferably, the particle size of the metal oxide is 100-300 nm.

16. The thermally conductive coating as described in claim 1 or 2, characterized in that, The solid content of the thermally conductive coating is 25-50 wt%; preferably, the QND-4 viscosity of the thermally conductive coating is 15-40 s.

17. A silicon steel sheet, characterized in that, The silicon steel sheet includes a silicon steel substrate and a thermally conductive coating on the surface of the silicon steel substrate, the thermally conductive coating being obtained by coating and baking the thermally conductive coating as described in any one of claims 1-13 on the surface of the silicon steel substrate.

18. The silicon steel sheet as described in claim 17, characterized in that, The single-sided dry film thickness of the thermally conductive coating is 0.5-2 μm.

19. The silicon steel sheet as described in claim 17, characterized in that, The thermal conductivity of the silicon steel sheet is ≥3W / (m·K).

20. The silicon steel sheet as described in claim 17, characterized in that, The bonding strength of the silicon steel sheet is 2-3.5 N / mm.

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