Self-bonding coating composition, self-bonding coated electrical steel sheet, method of forming the same, and method of producing laminated core

Abstract

A self-bonding coating composition, a self-bonding coated electrical steel sheet, a method of forming the same, and a method of producing a laminated core are provided. The self-bonding coating composition includes an aqueous hydroxyl-containing epoxy resin (A), an aqueous curing agent (B), an epoxy siloxane compound (C) and a siloxane compound (D). The self-bonding coated electrical steel sheet with improved corrosion resistance, insulation, high-temperature yellowness resistance and adhesive strength can be obtained by coating the self-bonding coating composition with specific composition content on the electrical steel sheet.

Description

Technical Field

[0001] This invention relates to a self-adhesive coating composition, and more particularly to a self-adhesive coating composition, a self-adhesive coated electromagnet sheet, a method for manufacturing the same, and a method for manufacturing a laminated iron core. Prior Technology

[0002] Electromagnetic steel (ES) sheets are used in the cores of generators, transformers, and motors, and are one of the important steel products. Generally, motor cores can be formed by welding or riveting electromagnetic steel sheets, but these processing methods still have drawbacks. For example, welding can easily cause short circuits at the core edges and a decrease in interlayer insulation, leading to thermal deformation or changes in magnetic properties. Furthermore, welding may generate harmful gases due to coating decomposition. Riveting uses localized rivet points for fixation, resulting in a weak connection strength in the core. Therefore, self-adhesive coated electromagnetic steel sheets represent a new and emerging assembly and bonding method.

[0003] The conventional self-bonding coating belongs to the C3 type organic resin system of ASTM A976 classification. The manufacturing method of steel strip using this self-bonding coating involves applying the self-bonding coating to the steel strip via roller coating on a coating production line (Stage A). After being heated and baked on the production line, this coating forms an incompletely cured coated steel strip (Stage B). The coated steel strip then undergoes coiling, customer slitting, stamping, stacking of loose sheets, and fixing with clamps before being heated and pressurized for curing (Stage C). The cured and bonded iron core avoids stress and iron loss variations caused by welding or riveting of the electromagnetic steel sheets, improves the overall performance of the motor, and reduces vibration and noise generated during iron core rotation. Therefore, self-bonding coating technology is suitable for high-specification thin electromagnetic steel sheets and high-efficiency motor products. However, steel sheets or iron cores produced by conventional self-bonding coatings are prone to severe yellowing due to excessively high heating temperatures.

[0004] In view of this, there is an urgent need to provide a self-adhesive coating composition, a self-adhesive coated electromagnetic steel sheet and a method for manufacturing the same, so as to improve the high-temperature yellowing problem of conventional self-adhesive coatings. Summary of the Invention

[0005] One aspect of the present invention is to provide a self-adhesive coating composition comprising a specific amount of waterborne hydroxyl epoxy resin (A), waterborne curing agent (B), epoxy-based silicone compound (C), and silicone compound (D) to improve the high-temperature yellowing and bonding strength problems of self-adhesive coatings.

[0006] Another aspect of the present invention is to provide a method for manufacturing a self-adhesive coated electromagnetic steel sheet, which involves coating an electromagnet steel sheet with a self-adhesive coating composition as described above.

[0007] Another aspect of the present invention is to provide a self-adhesive coated electromagnetic steel sheet, which is prepared by the method described above.

[0008] Another aspect of the present invention is to provide a method for manufacturing a multilayer iron core, which is to stack the self-adhesive coated electromagnetic steel sheets of the above-mentioned aspect.

[0009] According to one aspect of the present invention, a self-adhesive coating composition is provided, comprising an aqueous hydroxyl epoxy resin (A), an aqueous curing agent (B), an epoxy-based silicone compound (C), and a silicone compound (D) without epoxy groups. The aqueous hydroxyl epoxy resin (A) comprises 100 parts by weight, the aqueous curing agent (B) comprises 5 to 20 parts by weight, and the total content of the epoxy-based silicone compound (C) and the silicone compound (D) comprises 2.0 to 8.0 parts by weight. The weight ratio of the epoxy-based silicone compound (C) to the silicone compound (D) is 0.5:1 to 3:1.

[0010] According to one embodiment of the present invention, the above-mentioned water-based hardener (B) contains a carbodiimide compound.

[0011] According to one embodiment of the present invention, the above-mentioned epoxy-siloxane compound (C) has the structure shown in formula (I): (I).

[0012] In formula (I), R1 represents a group having an epoxy group, R2 represents an alkoxy group having 1 to 4 carbon atoms, R3 independently represents an alkoxy group having 1 to 4 carbon atoms or an alkyl group having 1 to 4 carbon atoms, X represents -CH2- or -O-, m1 represents 0 or 1, and n1 represents an integer from 0 to 3.

[0013] According to one embodiment of the present invention, the above-mentioned silicate compound (D) comprises a specific silicate compound (D1), which has the structure shown in formula (II): (II).

[0014] In formula (II), R 4 independently represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, R 5 independently represents an alkyl group having 1 to 4 carbon atoms, a is 0 or 1, b is 3 or 4, and the sum of a and b is 4.

[0015] According to one embodiment of the present invention, the above-mentioned silicate compound (D) comprises an aminosiloxane compound (D2), which has the structure shown in formula (III): (III).

[0016] In formula (III), R6 represents a primary amino group, a secondary amino group, or a tertiary amino group, R7 independently represents an alkoxy group with 1 to 4 carbon atoms, R8 represents an alkoxy group with 1 to 4 carbon atoms or an alkyl group with 1 to 4 carbon atoms, Y represents -CH2- or -NH-, where m2 represents 0 to 2 and n2 represents an integer from 0 to 3.

[0017] According to another aspect of the present invention, a method for manufacturing a self-adhesive coated electromagnet sheet is provided. The method includes applying the above-mentioned self-adhesive coating composition to the surface of the electromagnet sheet to form a coating on the surface; and performing a drying step on the coating to form a self-adhesive coated electromagnet sheet, wherein the drying temperature of the drying step is from 150°C to 330°C, and the self-adhesive coated electromagnet sheet includes a protective film.

[0018] According to one embodiment of the present invention, the thickness of the protective film is 0.8 micrometers to 8.0 micrometers.

[0019] According to another aspect of the present invention, a self-adhesive coated electromagnetic sheet is provided, which is manufactured using the above-described method for manufacturing a self-adhesive coated electromagnetic sheet.

[0020] According to another aspect of the present invention, a method for manufacturing a laminated iron core is provided. The method includes stacking a plurality of the above-described self-adhesive coated electromagnet sheets to obtain laminated electromagnet sheets; and a heating step of heating the laminated electromagnet sheets to form a laminated iron core, wherein the heating temperature of the heating step is from 70°C to 350°C.

[0021] According to one embodiment of the present invention, the heating frequency of the above heating step is 0.1 kHz to 1 kHz.

[0022] The self-adhesive coating composition, self-adhesive coated electromagnet sheet, its manufacturing method, and the manufacturing method of the laminated core of this invention are used to form a self-adhesive coated electromagnet sheet with corrosion resistance, insulation, and curing adhesion by comprising specific amounts of waterborne hydroxyl epoxy resin (A), waterborne curing agent (B), epoxy-based silicone compound (C), and silicone compound (D). Furthermore, by forming a cross-linked structure using a specific weight ratio of epoxy-based silicone compound (C) and silicone compound (D), the self-adhesive coated electromagnet sheet exhibits better resistance to high-temperature yellowing and better curing adhesion strength before and after high-temperature curing. Simple Explanation of the Diagram

[0023] none. Implementation

[0024] The manufacture and use of embodiments of the present invention are discussed in detail below. However, it will be understood that the embodiments provide many applicable inventive concepts that can be implemented in a wide variety of specific contexts. The specific embodiments discussed are for illustrative purposes only and are not intended to limit the scope of the invention.

[0025] As used in this invention, "around," "about," "approximately," or "substantially" generally mean within 20 percent, 10 percent, or 5 percent of the stated value or range.

[0026] As described above, this invention provides a self-adhesive coating composition, a self-adhesive coated electromagnet sheet, a method for manufacturing the same, and a method for manufacturing a laminated core. The self-adhesive coated electromagnet sheet is formed by comprising specific amounts of waterborne hydroxyl epoxy resin (A), waterborne curing agent (B), epoxy-based silicone compound (C), and silicone compound (D), thereby achieving corrosion resistance, insulation, and curing adhesion. Furthermore, a cross-linked structure is formed by a specific weight ratio of epoxy-based silicone compound (C) and silicone compound (D), resulting in better high-temperature yellowing resistance and curing adhesion strength before and after high-temperature curing of the self-adhesive coated electromagnet sheet.

[0027] Conventional self-adhesive coating compositions are prone to yellowing during high-temperature baking due to the poor anti-yellowing ability of epoxy resin itself. This leads to changes in the gloss of the formed coating, causing the finished iron core to fail to meet appearance inspection standards. A reasonable hypothesis for the yellowing of epoxy resin is that the benzene rings in the epoxy resin generate free radicals under high-temperature conditions. In the presence of oxygen, peroxide free radicals and peroxides are rapidly generated. These free radicals readily abstract hydrogen atoms from neighboring macromolecules, further accelerating the deterioration of the benzene rings. Therefore, this invention provides a self-adhesive coating composition comprising an aqueous hydroxyl epoxy resin (A), an aqueous curing agent (B), an epoxy-based silicone compound (C), and a silicone compound (D), wherein the silicone compound (D) does not possess epoxy groups.

[0028] In some embodiments, the waterborne hydroxyl epoxy resin (A) is a polymer compound containing two or more hydroxyl groups and two or more epoxy functional groups, wherein the number of hydroxyl groups can be, for example, two to one hundred, and it is generally a liquid oligomer with epoxy functional groups. The waterborne hydroxyl epoxy resin (A) can enhance the barrier effect of the formed coating, thereby inhibiting corrosion of the metal surface of the electromagnetic steel sheet. Therefore, a specific content of waterborne hydroxyl epoxy resin (A) can improve the anti-sticking properties, adhesion, corrosion resistance, insulation, and cured adhesion of the formed coating.

[0029] In some embodiments, the waterborne hydroxyl epoxy resin (A) may be a polymer synthesized from waterborne polyurethane, waterborne polyether polyol, waterborne polyester polyol, polyurea resin, polyolefin resin and / or waterborne epoxy resin, and acrylic acid and its derivatives, wherein acrylic acid and its derivatives include monomers such as acrylic acid, methacrylic acid, acrylate, methacrylate and its salts. In some specific examples, the waterborne hydroxyl epoxy resin (A) may be a copolymer of acrylic (polymethyl methacrylate) and epoxy resin, a copolymer of acrylic and polyurea resin, a copolymer of acrylic and polyolefin resin, or any combination thereof.

[0030] In some embodiments, the waterborne curing agent (B) comprises a carbodiimide compound. In some specific examples, the waterborne curing agent (B) may be N,N'-dicyclohexyl carbodiimide (DCC), N,N'-diisopropyl carbodiimide (DIC), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), or any combination thereof.

[0031] In some embodiments, the content of the waterborne hydroxyl epoxy resin (A) is 100 parts by weight, and the content of the waterborne curing agent (B) is about 5 parts by weight to about 20 parts by weight. If the content of the waterborne curing agent (B) is too low (e.g., less than 5 parts by weight), the adhesion of the self-adhesive coating composition will be insufficient; conversely, if the content of the waterborne curing agent (B) is too high (e.g., more than 20 parts by weight), the properties of the formed coating (e.g., corrosion resistance) may decrease.

[0032] To improve the yellowing and adhesion strength degradation of epoxy resin caused by high temperatures, the self-adhesive coating composition of this invention includes an epoxy-based silicone compound (C) and a silicone compound (D). Part of the silicone compound (C) enhances the compatibility and crosslinking properties with the waterborne hydroxyl epoxy resin (A), while the other part undergoes a sol-gel reaction to form a two-dimensional and / or three-dimensional crosslinked structure containing an inorganic Si-O bond framework, and can form Si-OM bonds at the interface with the steel sheet surface. By increasing the proportion of inorganic components, the problem of high-temperature yellowing of the resin is resisted, while simultaneously maintaining excellent adhesion strength of the coating.

[0033] In some embodiments, the epoxy siloxane compound (C) has the structure shown in formula (I): (I).

[0034] In formula (I), R1 represents a group having an epoxy group, R2 represents an alkoxy group having 1 to 4 carbon atoms, R3 independently represents an alkoxy group having 1 to 4 carbon atoms or an alkyl group having 1 to 4 carbon atoms, X represents -CH2- or -O-, m1 represents 0 or 1, and n1 represents an integer from 0 to 3.

[0035] In some specific examples, the epoxysiloxane compound (C) may include, but is not limited to, γ-epoxypropylpropyltrimethoxysilane, γ-epoxypropylpropyltriethoxysilane, γ-epoxypropylpropylmethyldiethoxysilane, or combinations thereof.

[0036] In some embodiments, the content of the aqueous hydroxyl epoxy resin (A) is 100 parts by weight, and the total content of the epoxy-based silicone compound (C) and silicone compound (D) is about 2.0 parts by weight to about 8.0 parts by weight. When the total content of the epoxy-based silicone compound (C) and silicone compound (D) is too low (e.g., less than 2.0 parts by weight), the high-temperature yellowing problem of the formed coating film cannot be improved; conversely, if the total content of the epoxy-based silicone compound (C) and silicone compound (D) is too high (e.g., greater than 8.0 parts by weight), the adhesive strength of the formed coating film will be reduced.

[0037] Epoxy-based silicone compound (C) is the main component in the hydrolysis-condensation reaction, and is combined with silicone compound (D) to form a water-soluble oligomer or prepolymer. In some embodiments, the weight ratio of epoxy-based silicone compound (C) to silicone compound (D) is from about 0.5:1 to about 3:1. If the relative content of epoxy-based silicone compound (C) is too high (e.g., a weight ratio greater than 3:1), the high-temperature yellowing problem of the coating film cannot be effectively improved, and the stability of the coating film is poor; conversely, if the relative content of epoxy-based silicone compound (C) is too low (e.g., a weight ratio less than 0.5:1), the adhesive strength of the coating film may be insufficient.

[0038] In some embodiments, the siloxane compound (D) comprises a specific siloxane compound (D1) and / or an aminosiloxane compound (D2). In other words, the siloxane compound (D) may comprise only one of the specific siloxane compound (D1) and the aminosiloxane compound (D2), or may comprise both the specific siloxane compound (D1) and the aminosiloxane compound (D2). In some embodiments where the siloxane compound (D) comprises both the specific siloxane compound (D1) and the aminosiloxane compound (D2), the weight ratio of the specific siloxane compound (D1) to the aminosiloxane compound (D2) is from 0.5:1.0 to 1:1. When the siloxane compound (D) contains a specific siloxane compound (D1) and an amino siloxane compound (D2) in the aforementioned weight ratio, the reaction of the siloxane compound (D) with the epoxy siloxane compound (C) can result in a coating film with better resistance to high-temperature yellowing, corrosion resistance, and high-temperature adhesion strength.

[0039] In some embodiments, a particular siloxane compound (D1) has the structure shown in formula (II): (II).

[0040] In formula (II), R 4 independently represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, R 5 independently represents an alkyl group having 1 to 4 carbon atoms, a is 0 or 1, b is 3 or 4, and the sum of a and b is 4.

[0041] In some specific examples, a particular siloxane compound (D1) may include, but is not limited to, tetramethoxysilane, ethyltrimethoxysilane, tetraethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, or combinations thereof.

[0042] In some embodiments, the aminosiloxane compound (D2) has the structure shown in formula (III): (III).

[0043] In formula (III), R6 represents a primary amino group, a secondary amino group, or a tertiary amino group, R7 independently represents an alkoxy group with 1 to 4 carbon atoms, R8 represents an alkoxy group with 1 to 4 carbon atoms or an alkyl group with 1 to 4 carbon atoms, Y represents -CH2- or -NH-, where m2 represents 0 to 2 and n2 represents an integer from 0 to 3.

[0044] In some specific examples, the aminosiloxane compound (D2) may include, but is not limited to, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β(aminoethyl)-γ-aminopropylmethyldiethoxysilane, N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropyltriethoxysilane, or combinations thereof.

[0045] The present invention also provides a method for manufacturing a self-adhesive coated electromagnetic steel sheet, which includes coating the above-mentioned self-adhesive coating composition onto the surface of the electromagnetic steel sheet to form a coating. In some embodiments, based on the electromagnetic steel sheet being 100 wt%, the electromagnetic steel sheet contains no more than 0.005 wt% carbon, 2 wt% to 4 wt% silicon, no more than 2 wt% aluminum, 0.1 wt% to 1.0 wt% manganese, no more than 0.05 wt% phosphorus, no more than 0.005 wt% sulfur, no more than 0.005 wt% nitrogen, no more than 0.003 wt% titanium, 0.05 wt% to 0.95 wt% nickel, unavoidable impurities, and a balanced amount of iron, wherein the total content of silicon and aluminum is no more than 5 wt%.

[0046] After the coating is formed on the surface of the electromagnet sheet, a drying step is performed on the coating to form a self-adhesive coated electromagnet sheet. In some embodiments, the drying temperature of the drying step is from about 150°C to about 330°C, and the drying time is from about 5 seconds to about 1 minute.

[0047] The self-adhesive coated electromagnetic steel sheet comprises a protective film formed after the coating has been dried and cured. In some embodiments, the thickness of the protective film is from about 0.8 micrometers to about 8.0 micrometers, preferably from about 1.0 micrometers to about 5.5 micrometers. When the thickness of the protective film is within the aforementioned range, the protective film provides good corrosion protection and adhesion strength for the electromagnetic steel sheet.

[0048] The present invention also provides a method for manufacturing a laminated iron core, which includes stacking a plurality of the above-described self-adhesive coated electromagnet sheets to obtain laminated electromagnet sheets. Next, the laminated electromagnet sheets are heated using an induction heating device to form a laminated iron core. In some embodiments, the heating device includes a lower cover plate configured to support the bottom of the laminated iron core, an upper cover plate configured to cover the top of the laminated iron core, a coil assembly disposed around the laminated iron core, and a power supply connected to the coil assembly to provide current to the coil assembly. In some embodiments, the heating temperature of the heating step is from about 70°C to about 350°C, and the heating time is from about 5 minutes to about 10 minutes. In some embodiments, the heating frequency of the heating step is from about 0.1 kHz to about 1 kHz.

[0049] The following examples illustrate the application of the present invention, but they are not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention.

[0050] Example 1 (E1)

[0051] The self-adhesive coating composition used in Example 1 comprises an aqueous hydroxyl epoxy resin (A), a carbodiimide-containing aqueous curing agent (B), γ-glycidylpropyltrimethoxysilane (C1) as an epoxy-based silicone compound (C), and tetraethoxysilane (specific silicone compound (D1)) as a silicone compound (D). The aqueous hydroxyl epoxy resin (A) comprises 100 parts by weight, the carbodiimide-containing aqueous curing agent (B) comprises 8 parts by weight, the epoxy-based silicone compound (C) comprises 0.6 parts by weight, and the silicone compound (D) comprises 1.2 parts by weight.

[0052] After sequentially cleaning and drying the surface of the electromagnet sheet, the self-adhesive coating composition of Example 1 was applied to the surface of the electromagnet sheet using a roller coating method. Next, the coated electromagnet sheet was placed in a thermal cycling oven for curing to obtain the self-adhesive coated electromagnet sheet of Example 1, wherein the protective film thickness of the self-adhesive coated electromagnet sheet was 3.0 micrometers. Then, the self-adhesive coated electromagnet sheet was evaluated using the following evaluation methods, and the evaluation results are shown in Table 2.

[0053] Examples 2 to 6 (E2 to E6) and Comparative Examples 1 to 3 (C1 to C3)

[0054] Examples 2 to 6 and Comparative Examples 1 to 3 were prepared using a method similar to that of Example 1, with the only difference being the composition and content ratio of the self-adhesive coating composition. The composition and content ratio of the self-adhesive coating composition used in Examples 2 to 6 and Comparative Examples 1 to 3 are shown in Table 1 below. The evaluation results of the self-adhesive coated electromagnets of Examples 2 to 6 and Comparative Examples 1 to 3 are shown in Table 2.

[0055] Table 1 Waterborne hydroxyl epoxy resin (A) Water-based hardener (B) Epoxysiloxane compounds (C) Silicon oxide compounds (D) C1 C2 D1 D2 E1 100 8 0.6 - 1.2 - E2 100 9 3 - 2 - E3 100 10 6 - 2 - E4 100 12 - 4.5 0.5 1 E5 100 15 - 3 - 1.5 E6 100 20 - 2 - 2 C1 100 8 - - 5 - C2 100 10 1 - 4 - C3 100 15 5 - - 5 B: Aqueous hardener containing carbodiimide groups C1: γ-glycidylpropyltrimethoxysilane C2: γ-Epoxypropylpropyltriethoxysilane D1: Tetraethoxysilane D2: γ-aminopropyltriethoxysilane

[0056] Evaluation methods

[0057] The self-adhesive coated electromagnetic steel sheets prepared in Examples 1 to 6 and Comparative Examples 1 to 3 were subjected to the following tests, and the results are shown in Table 2.

[0058] 1. Resistance to high-temperature yellowing

[0059] The self-adhesive coated electromagnetic steel sheet prepared above was placed in a high-temperature environment of 220°C for 15 minutes, and the high-temperature resistance of the coating surface was visually evaluated. The evaluation criteria are as follows: ◎: The appearance of the protective film after the high-temperature test is the same as that of the protective film that has not undergone the high-temperature test (the original protective film); ○: The appearance of the protective film after the high-temperature test is slightly different from that of the original protective film; △: The protective film after the high-temperature test shows obvious yellowing or darkening compared to the original protective film; ╳: After the high-temperature test, the appearance of the protective film is obviously yellowed or darkened compared to the original protective film, and there are obvious cracks on the surface of the protective film.

[0060] 2. Corrosion resistance

[0061] A salt spray test was conducted using the JIS Z-2371 standard method. After 5 hours of testing, the area of ​​white rust formation on the steel plate surface was visually evaluated. A smaller white rust formation area (rusted area) indicates better corrosion resistance. The relevant evaluation criteria are as follows: ◎: 0% ≤ rusted area < 25%; ○: 25% ≤ rusted area < 50%; △: 50% ≤ rusted area < 75%; ╳: Rusted area ≥ 75%.

[0062] 3. Insulation

[0063] Insulation performance was assessed according to the JIS-C2550 standard method, using an interlayer impedance meter to measure the interlayer impedance of the self-adhesive coated electromagnetic steel sheet. Specific evaluation criteria are as follows: ◎: 25 Ω-cm² / sheet ≤ interlayer impedance; ○: 10 Ω-cm² / piece ≤ interlayer impedance < 25 Ω-cm² / piece; △: 5 Ω-cm² / piece ≤ interlayer impedance < 10 Ω-cm² / piece; ╳: Interlayer impedance ≥ 5Ω-cm² / piece.

[0064] 4. Cured bond strength

[0065] The self-adhesive coated electromagnetic steel sheets were pressed together at 200°C for 60 seconds and a pressure of 3 N / mm². The shear stress was then tested at room temperature using a universal tensile testing machine, and the maximum value was taken as the bond strength. The test speed was 10 mm / min. The relevant evaluation criteria are as follows: ◎: 10 N / mm² ≤ Maximum shear stress < 20 N / mm²; ○: 5 N / mm² ≤ maximum shear stress < 10 N / mm²; △: 1 N / mm² ≤ maximum shear stress < 5 N / mm²; ╳: 0 N / mm 2≤ Maximum shear stress < 1 N / mm 2.

[0066] 5. Bond strength after high-temperature curing

[0067] After placing the self-adhesive coated electromagnetic steel sheet at 200°C for 168 hours, it was removed and cooled to room temperature. It was then pressed together at 200°C for 60 seconds and a pressure of 3 N / mm², and its shear stress was tested at room temperature using a universal tensile testing machine. The maximum value was taken as the bond strength. The test speed was 10 mm / min. The relevant evaluation criteria are as follows: ◎: 10 N / mm² ≤ Maximum shear stress < 20 N / mm²; ○: 5 N / mm² ≤ maximum shear stress < 10 N / mm²; △: 1 N / mm² ≤ maximum shear stress < 5 N / mm²; ╳: 0 N / mm 2≤ Maximum shear stress < 1 N / mm 2.

[0068] Table 2 High temperature yellowing resistance corrosion resistance insulation Curing bond strength Bond strength after high temperature curing E1 ○ ○ ◎ ◎ ○ E2 ◎ ◎ ◎ ◎ ◎ E3 ◎ ◎ ◎ ◎ ○ E4 ◎ ◎ ◎ ◎ ◎ E5 ◎ ○ ◎ ◎ ◎ E6 ◎ ○ ◎ ◎ ◎ C1 ○ ╳ △ ╳ ╳ C2 △ ╳ △ ╳ ╳ C3 ╳ ╳ ╳ ╳ ╳

[0069] As can be seen from Tables 1 and 2 above, the self-adhesive coated electromagnetic steel sheets prepared in Examples 1 to 6 can simultaneously possess good resistance to high-temperature yellowing, corrosion resistance, insulation, and curing bonding strength before and after high temperature. In contrast, the self-adhesive coating composition of Comparative Example 1 does not contain epoxy-based silicone compounds (C), therefore its self-adhesive coated electromagnetic steel sheet has poor corrosion resistance and poor curing bond strength before and after high temperature; in the self-adhesive coating composition of Comparative Example 2, the content of epoxy-based silicone compounds (C) relative to silicone compounds (D) is too low, that is, its weight ratio is not within a specific range, therefore its self-adhesive coated electromagnetic steel sheet has poor corrosion resistance and poor curing bond strength before and after high temperature; while in the self-adhesive coating composition of Comparative Example 3, the total content of epoxy-based silicone compounds (C) and silicone compounds (D) is too high, therefore its self-adhesive coated electromagnetic steel sheet has poor high-temperature yellowing resistance, corrosion resistance, insulation, and poor curing bond strength before and after high temperature.

[0070] According to the above embodiments, the self-adhesive coating composition, self-adhesive coated electromagnet sheet, its manufacturing method, and the manufacturing method of the laminated core provided by the present invention utilize waterborne hydroxyl epoxy resin (A), waterborne curing agent (B), epoxy-based silicone compound (C), and silicone compound (D) in specific amounts to form a self-adhesive coated electromagnet sheet with corrosion resistance, insulation, and curing adhesion. Furthermore, by forming a cross-linked structure using epoxy-based silicone compound (C) and silicone compound (D) in a specific weight ratio, the self-adhesive coated electromagnet sheet exhibits better resistance to high-temperature yellowing and better curing adhesion strength before and after high-temperature curing.

[0071] Although the present invention has been disclosed above with reference to several embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the technical field to which this invention pertains may make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of this invention shall be determined by the appended claims.

[0072] none

[0073] Domestic storage information (please note in order of storage institution, date, and number) none Overseas storage information (please note in the order of storage country, institution, date, and number) none

Claims

1. A self-adhesive coating composition comprising: an aqueous hydroxyl epoxy resin (A); an aqueous curing agent (B), wherein the aqueous hydroxyl epoxy resin (A) comprises 100 parts by weight and the aqueous curing agent (B) comprises 5 to 20 parts by weight; an epoxy-based silicone compound (C); and a silicone compound (D), wherein the silicone compound (D) does not have an epoxy group, wherein the total content of the epoxy-based silicone compound (C) and the silicone compound (D) comprises 2.0 to 8.0 parts by weight and the weight ratio of the epoxy-based silicone compound (C) to the silicone compound (D) is 0.5:1 to 3:

1.

2. The self-adhesive coating composition as claimed in claim 1, wherein the waterborne curing agent (B) comprises a carbodiimide compound.

3. The self-adhesive coating composition as claimed in claim 1, wherein the epoxy siloxane compound (C) has the structure shown in formula (I): (I) In formula (I), R1 represents a group having an epoxy group, R2 represents an alkoxy group having 1 to 4 carbon atoms, R3 independently represents an alkoxy group having 1 to 4 carbon atoms or an alkyl group having 1 to 4 carbon atoms, X represents -CH2- or -O-, m1 represents 0 or 1, and n1 represents an integer from 0 to 3.

4. The self-adhesive coating composition as claimed in claim 1, wherein the siloxane compound (D) comprises a specific siloxane compound (D1) having the structure shown in formula (II): (II) In formula (II), R 4 independently represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, R 5 independently represents an alkyl group having 1 to 4 carbon atoms, a is 0 or 1, b is 3 or 4, and the sum of a and b is 4.

5. The self-adhesive coating composition as claimed in claim 1 or 4, wherein the siloxane compound (D) comprises an aminosiloxane compound (D2) having a structure as shown in formula (III): (III) In formula (III), R6 represents a primary amino group, a secondary amino group, or a tertiary amino group, R7 independently represents an alkoxy group having 1 to 4 carbon atoms, R8 represents an alkoxy group having 1 to 4 carbon atoms or an alkyl group having 1 to 4 carbon atoms, Y represents -CH2- or -NH-, wherein m2 represents 0 to 2, and n2 represents an integer from 0 to 3.

6. A method for manufacturing a self-adhesive coated electromagnet sheet, comprising: applying a self-adhesive coating composition according to any one of claims 1 to 5 onto a surface of an electromagnet sheet to form a coating on the surface; and performing a drying step on the coating to form the self-adhesive coated electromagnet sheet, wherein a drying temperature of the drying step is from 150°C to 330°C, and the self-adhesive coated electromagnet sheet includes a protective film.

7. A method for manufacturing a self-adhesive coated electromagnetic steel sheet as described in claim 6, wherein one of the protective films has a thickness of 0.8 micrometers to 8.0 micrometers.

8. A self-adhesive coated electromagnetic sheet, which is manufactured using the manufacturing method of the self-adhesive coated electromagnetic sheet described in claim 6 or 7.

9. A method for manufacturing a laminated iron core, comprising: stacking a plurality of self-adhesive coated electromagnet sheets as described in claim 8 to obtain a laminated electromagnet sheet; and performing a heating step on the laminated electromagnet sheet to form the laminated iron core, wherein a heating temperature of the heating step is from 70°C to 350°C.

10. A method for manufacturing a laminated core as claimed in claim 9, wherein a heating frequency of the heating step is from 0.1 kHz to 1 kHz.