Aluminum cover plate for drilling with water-soluble coating and preparation method thereof

Abstract

The present invention relates to the technical field of aluminum cover plates for drilling, and discloses an aluminum cover plate for drilling with a water-soluble coating and a preparation method thereof. The aluminum cover plate for drilling prepared by the present invention is made by coating a surface of an aluminum sheet with a water-soluble coating. The water-soluble coating comprises the following raw materials in parts by weight: 25-35 parts of polyvinyl alcohol, 20-40 parts of polyacrylic acid, 8-15 parts of reinforcing filler, 3-7 parts of polyvinyl pyrrolidone, 3-7 parts of modified hyperbranched polyether, and 0.1-0.3 parts of a defoamer. The coating has excellent adhesion, heat dissipation, and heat resistance on the surface of the aluminum sheet, and has good plastic deformation ability, thereby extending the service life of the aluminum cover plate.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum cover plates for drilling, and in particular to an aluminum cover plate for drilling with a water-soluble coating and a preparation method thereof. Background Art

[0002] PCBs are widely used in medical devices, industrial equipment, communications equipment, automotive electronics, and household appliances. The drilling process is crucial in PCB manufacturing. To protect the PCB and improve drilling quality, a cover material is often required. This material, placed on the copper-clad laminate being processed, is called a "cover." Cover materials include phenolic resin, epoxy glass cloth, ordinary aluminum foil, and resin-coated aluminum. Compared to other cover materials, resin-coated aluminum cover offers many unique advantages. These not only effectively improve the quality of the drilled holes and extend the life of the drill bit, but can also be used to increase the number of stacked boards, significantly improving drilling efficiency.

[0003] However, during the PCB drilling process, the drill bit generates a significant amount of heat. If this heat cannot be dissipated promptly, the drill bit temperature will rise, affecting drilling accuracy and drill life. Therefore, the water-soluble coating on the aluminum cover plate surface needs to have good thermal conductivity to quickly dissipate the heat generated by the drill bit during drilling, reducing the drill bit temperature, protecting the drill bit, and ensuring drilling accuracy. In addition, it needs to provide lubrication and cushioning functions to meet actual production needs. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides an aluminum cover plate for drilling with a water-soluble coating and a preparation method thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A drilling aluminum cover plate with a water-soluble coating comprises a water-soluble coating and an aluminum sheet; the water-soluble coating is formed by coating a water-soluble paint on the surface of the aluminum sheet;

[0007] The water-soluble coating comprises the following raw materials in parts by weight: 25-35 parts of polyvinyl alcohol, 20-40 parts of polyacrylic acid, 5-9 parts of reinforcing filler, 3-7 parts of polyvinyl pyrrolidone, 3-7 parts of modified hyperbranched polyether, and 0.1-0.3 parts of defoaming agent;

[0008] The defoamer is one of BYK024 or BYK028;

[0009] The reinforcing filler is prepared by the following steps:

[0010] Step A1, nano boron carbide (B4C) is evenly dispersed in a mixture of deionized water and ethanol, ultrasonically treated for 0.5-1h, 0.1mol / L hexadecyltrimethylammonium bromide is added and mixed and stirred evenly, the pH is adjusted to 8-9, stirring is continued for 10min, and the temperature is raised to 35-45°C, and tetraethyl orthosilicate is then added three times, each with an interval of 2h. Finally, the reaction is stirred for 24h, filtered, washed, and the product is collected. The product is redispersed in an ethanolamine ethanol solution and refluxed at 90°C for 12h. The extraction is repeated once, filtered, washed, and dried to obtain B4C@SiO2 nanomaterial;

[0011] Step A2: Disperse the B4C@SiO2 nanomaterial evenly in a 1 mol / L Tris-HCl buffer solution with a pH of 8-8.5, add deionized water and ultrasonically disperse for 15-25 minutes, then heat to 30-40°C, add dopamine hydrochloride and stir to react for 5-10 hours, centrifuge, wash, and dry to obtain a reinforcing filler;

[0012] Furthermore, in step A1, the usage ratio of nano-boron carbide, deionized water, ethanol, hexadecyltrimethylammonium bromide, tetraethyl orthosilicate and ethanolamine ethanol solution is 2-4 g: 70 mL: 30 mL: 3-5 mL: 1.5-3 mL: 100 mL;

[0013] Furthermore, in step A1, the volume ratio of ethanolamine to ethanol in the ethanolamine-ethanol solution is 1:4;

[0014] Furthermore, in step A2, the usage ratio of B4C@SiO2 nanomaterial, Tris-HCl buffer solution, deionized water and dopamine hydrochloride is 1-3 g: 5 mL: 100 mL: 0.3-0.6 g.

[0015] The modified hyperbranched polyether is prepared by the following steps:

[0016] Step B1, tris(hydroxymethyl)aminomethane and sodium hydroxide are mixed and stirred in ethanol, ethyl glycidyl ether is added and stirred for 2.5-3.5 hours, and distilled under reduced pressure, filtered, washed, and dried to obtain an ether-containing monomer;

[0017] Step B2, triglycidyl isocyanurate and tetrabutylammonium bromide are mixed and stirred in N,N-dimethylformamide, and then the ether-containing monomer is added. Under nitrogen conditions, the temperature is raised to 90-100° C. and the reaction is carried out for 3.5-4.5 hours. Then, tetrahydrofuran is added and stirred for 5-10 minutes, and the mixture is washed alternately with 80° C. hot water and cold ether, filtered, and dried to obtain a hyperbranched polyether;

[0018] Step B3, mixing the hyperbranched polyether and sodium hydroxide in N,N-dimethylformamide and stirring evenly, then adding 5-aminoisophthalic acid and stirring to react for 2-4 hours, and distilling under reduced pressure to obtain the modified hyperbranched polyether;

[0019] Furthermore, in step B1, the ratio of tris(hydroxymethyl)aminomethane, sodium hydroxide, ethanol and ethyl glycidyl ether is 0.01-0.03 mol: 0.03-0.06 g: 50 mL: 0.012-0.033 mol;

[0020] Furthermore, in step B2, the usage ratio of triglycidyl isocyanurate, tetrabutylammonium bromide, N,N-dimethylformamide, ether-containing monomer, tetrahydrofuran, hot water and cold diethyl ether is 0.01-0.03 mol: 0.0005-0.0015 mol: 100 mL: 1.5-3.5 g: 30 mL: 50 mL: 50 mL;

[0021] Furthermore, in step B3, the usage ratio of the hyperbranched polyether, sodium hydroxide, N,N-dimethylformamide and 5-aminoisophthalic acid is 5-10 g: 0.1-0.8 g: 100 mL: 1-3 g.

[0022] A method for preparing an aluminum cover plate for drilling with a water-soluble coating comprises the following steps:

[0023] Step S1, weighing raw materials in parts by weight, mixing and stirring polyvinyl alcohol, polyacrylic acid, polyvinyl pyrrolidone, modified hyperbranched polyether, defoaming agent and reinforcing filler to obtain a water-soluble coating;

[0024] Step S2: evenly apply the water-soluble coating on the aluminum sheet to form a coating with a thickness of 0.15 mm, and dry it to obtain an aluminum cover plate for drilling with a water-soluble coating.

[0025] Beneficial effects of the present invention:

[0026] The aluminum cover plate for drilling prepared by the present invention is made by coating an aluminum sheet with a water-soluble coating on its surface. The water-soluble coating exhibits excellent plastic deformation properties on the aluminum sheet surface, extending the service life of the aluminum cover plate. Furthermore, the water-soluble coating is made from highly water-soluble polyvinyl alcohol and polyacrylic acid, with the addition of polyvinyl pyrrolidone, modified hyperbranched polyether, and enhanced strength, while maintaining water solubility to improve the coating's adhesion, heat dissipation, and heat resistance.

[0027] The reinforcing filler was first synthesized on the surface of boron carbide using hexadecyltrimethylammonium bromide as a template and tetraethyl orthosilicate as a raw material to produce a B4C@SiO2 nanomaterial. Polydopamine was then synthesized on the surface of the B4C@SiO2 nanomaterial using dopamine hydrochloride as a raw material to produce a reinforcing filler. The reinforcing filler introduced into the coating promotes heat transfer, improves the coating's heat dissipation, and reduces wire entanglement caused by high heat during drilling, thereby improving drilling quality and efficiency. It also enhances the coating's plastic deformation capacity, ensuring it can adapt to the drill bit's cutting motion during drilling, reducing the risk of drill bit breakage and detachment. It also allows the coating to better adapt to the friction and shear forces generated during drilling, thereby ensuring the coating's integrity and uniformity. Furthermore, the polydopamine layer coating the reinforcing filler has a catechol structure, which exhibits excellent adhesion. This structure improves the coating's adhesion to the aluminum sheet, reduces cracking during drilling, and increases the sheet's service life.

[0028] In the modified hyperbranched polyether, tris(hydroxymethyl)aminomethane) and ethyl glycidyl ether are first reacted to produce an ether-containing monomer. Triglycidyl isocyanurate and the ether-containing monomer are then used as raw materials to synthesize a hyperbranched polyether containing a triazine structure. Finally, the hyperbranched polyether is reacted with 5-aminoisophthalic acid to produce the modified hyperbranched polyether. The modified hyperbranched polyether has a highly branched three-dimensional structure, which allows for a large number of vacancies within the molecule, making it easier for heat to transfer through these vacancies, thereby enhancing the heat dissipation effect of the coating. The introduced triazine structure has excellent heat resistance, which can improve the heat resistance of the coating, allowing the coating on the aluminum sheet surface to withstand higher drilling temperatures and resist deformation and shedding. Furthermore, the active groups (carboxyl and hydroxyl groups) at the ends of the modified hyperbranched polyether can react chemically with oxides on the aluminum sheet surface to form stable chemical bonds. This bonding action gives the coating better bonding strength to the aluminum sheet surface, thereby increasing the service life of the aluminum sheet. DETAILED DESCRIPTION

[0029] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0030] Example 1: The reinforcing filler is prepared by the following steps:

[0031] Step A1, 2g of nano-boron carbide (B4C) was evenly dispersed in a mixture of 70mL of deionized water and 30mL of ethanol, ultrasonically treated for 0.5h, 3mL of 0.1mol / L hexadecyltrimethylammonium bromide was added and mixed and stirred evenly, the pH was adjusted to 8, stirring was continued for 10min, and the temperature was raised to 35°C, and then 1.5mL of tetraethyl orthosilicate was added three times, each time with an interval of 2h, and finally stirred for 24h, filtered, washed, and collected. The product was redispersed in 100mL of ethanolamine ethanol solution, and refluxed at 90°C for 12h, and the extraction was repeated once, filtered, washed, and dried to obtain B4C@SiO2 nanomaterial, and the volume ratio of ethanolamine to ethanol in the ethanolamine ethanol solution was 1:4;

[0032] Step A2: Disperse 1 g of B4C@SiO2 nanomaterial evenly in 5 mL of 1 mol / L Tris-HCl buffer solution with a pH of 8, add 100 mL of deionized water and ultrasonically disperse for 15 min. Then, heat to 30°C, add 0.3 g of dopamine hydrochloride and stir to react for 5 h. Centrifuge, wash, and dry to obtain a reinforced filler.

[0033] The modified hyperbranched polyether is prepared by the following steps:

[0034] Step B1, 0.01 mol of tris(hydroxymethyl)aminomethane and 0.03 g of sodium hydroxide were mixed and stirred in 50 mL of ethanol, 0.012 mol of ethyl glycidyl ether was added, and stirred for 2.5 h. The mixture was distilled under reduced pressure, filtered, washed, and dried to obtain an ether-containing monomer;

[0035] Step B2, 0.01 mol of triglycidyl isocyanurate and 0.0005 mol of tetrabutylammonium bromide were mixed and stirred in 100 mL of N,N-dimethylformamide, and then 1.5 g of ether-containing monomer was added. Under nitrogen conditions, the temperature was raised to 90 ° C. and reacted for 3.5 hours. Then 30 mL of tetrahydrofuran was added and stirred for 5 minutes. The mixture was washed alternately with 50 mL, 80 ° C hot water and 50 mL of cold ether, filtered and dried to obtain a hyperbranched polyether;

[0036] Step B3: 5 g of the hyperbranched polyether and 0.1 g of sodium hydroxide were mixed and stirred in 100 mL of N,N-dimethylformamide, and then 1 g of 5-aminoisophthalic acid was added and stirred for 2 h, and then distilled under reduced pressure to obtain the modified hyperbranched polyether.

[0037] Example 2: The reinforcing filler is prepared by the following steps:

[0038] Step A1, 3g of nano-boron carbide (B4C) was evenly dispersed in a mixture of 70mL of deionized water and 30mL of ethanol, ultrasonically treated for 0.8h, 4mL of 0.1mol / L hexadecyltrimethylammonium bromide was added and mixed and stirred evenly, the pH was adjusted to 8.5, stirring was continued for 10min, and the temperature was raised to 40°C, and then 2.2mL of tetraethyl orthosilicate was added three times, each time with an interval of 2h, and finally stirred for 24h, filtered, washed, and collected. The product was redispersed in 100mL of ethanolamine ethanol solution, and refluxed at 90°C for 12h, and the extraction was repeated once, filtered, washed, and dried to obtain B4C@SiO2 nanomaterial, and the volume ratio of ethanolamine to ethanol in the ethanolamine ethanol solution was 1:4;

[0039] Step A2: Disperse 2 g of B4C@SiO2 nanomaterial evenly in 5 mL of 1 mol / L Tris-HCl buffer solution with a pH of 8.3, add 100 mL of deionized water and ultrasonically disperse for 20 min. Then, heat to 35°C, add 0.45 g of dopamine hydrochloride and stir to react for 7 h. Centrifuge, wash, and dry to obtain a reinforced filler.

[0040] The modified hyperbranched polyether is prepared by the following steps:

[0041] Step B1, 0.02 mol of tris(hydroxymethyl)aminomethane and 0.045 g of sodium hydroxide were mixed and stirred in 50 mL of ethanol, 0.022 mol of ethyl glycidyl ether was added, and stirred for 3 h. The mixture was distilled under reduced pressure, filtered, washed, and dried to obtain an ether-containing monomer;

[0042] Step B2, 0.02 mol of triglycidyl isocyanurate and 0.001 mol of tetrabutylammonium bromide were mixed and stirred in 100 mL of N, N-dimethylformamide, and then 2.5 g of ether-containing monomer was added. Under nitrogen conditions, the temperature was raised to 95 ° C. and reacted for 4 hours. Then 30 mL of tetrahydrofuran was added and stirred for 7.5 minutes. The mixture was washed alternately with 50 mL, 80 ° C hot water and 50 mL of cold ether, filtered and dried to obtain a hyperbranched polyether;

[0043] Step B3: 7.5 g of the hyperbranched polyether and 0.5 g of sodium hydroxide were mixed and stirred in 100 mL of N,N-dimethylformamide, and then 2 g of 5-aminoisophthalic acid was added and stirred for 3 h, and then distilled under reduced pressure to obtain the modified hyperbranched polyether.

[0044] Example 3: Reinforced filler is prepared by the following steps:

[0045] Step A1, 4g of nano-boron carbide (B4C) was evenly dispersed in a mixture of 70mL of deionized water and 30mL of ethanol, ultrasonically treated for 1h, 5mL of 0.1mol / L hexadecyltrimethylammonium bromide was added and mixed and stirred evenly, the pH was adjusted to 9, stirring was continued for 10min, and the temperature was raised to 45°C, and then 3mL of tetraethyl orthosilicate was added three times, each time with an interval of 2h, and finally stirred for 24h, filtered, washed, and collected. The product was redispersed in 100mL of ethanolamine ethanol solution, and refluxed at 90°C for 12h, and the extraction was repeated once, filtered, washed, and dried to obtain B4C@SiO2 nanomaterial, and the volume ratio of ethanolamine to ethanol in the ethanolamine ethanol solution was 1:4;

[0046] Step A2: Disperse 3 g of B4C@SiO2 nanomaterial evenly in 5 mL of 1 mol / L Tris-HCl buffer solution with a pH of 8.5, add 100 mL of deionized water and ultrasonically disperse for 25 min. Then, heat to 40°C, add 0.6 g of dopamine hydrochloride and stir to react for 10 h. Centrifuge, wash, and dry to obtain a reinforced filler.

[0047] The modified hyperbranched polyether is prepared by the following steps:

[0048] Step B1, 0.03 mol of tris(hydroxymethyl)aminomethane and 0.06 g of sodium hydroxide were mixed and stirred in 50 mL of ethanol, 0.033 mol of ethyl glycidyl ether was added, and stirred for 3.5 hours, and the mixture was distilled under reduced pressure, filtered, washed, and dried to obtain an ether-containing monomer;

[0049] Step B2, 0.03 mol of triglycidyl isocyanurate and 0.0015 mol of tetrabutylammonium bromide were mixed and stirred in 100 mL of N, N-dimethylformamide, and then 3.5 g of ether-containing monomer was added. Under nitrogen conditions, the temperature was raised to 100 ° C. and reacted for 4.5 hours. Then 30 mL of tetrahydrofuran was added and stirred for 10 minutes. The mixture was washed alternately with 50 mL, 80 ° C hot water and 50 mL of cold ether, filtered and dried to obtain a hyperbranched polyether;

[0050] Step B3: 10 g of the hyperbranched polyether and 0.8 g of sodium hydroxide were mixed and stirred in 100 mL of N,N-dimethylformamide, and then 3 g of 5-aminoisophthalic acid was added and stirred for 4 h, and then distilled under reduced pressure to obtain the modified hyperbranched polyether.

[0051] Example 4: A method for preparing an aluminum cover plate for drilling with a water-soluble coating comprises the following steps:

[0052] Step S1, weighing raw materials by weight, mixing and stirring 25 parts of polyvinyl alcohol, 20 parts of polyacrylic acid, 3 parts of polyvinyl pyrrolidone, 3 parts of the modified hyperbranched polyether prepared in Example 1, 0.1 part of the defoamer BYK024, and 5 parts of the reinforcing filler prepared in Example 1 to obtain a water-soluble coating;

[0053] Step S2: evenly apply the water-soluble coating on the aluminum sheet to form a coating with a thickness of 0.15 mm, and dry it to obtain an aluminum cover plate for drilling with a water-soluble coating.

[0054] Example 5: A method for preparing an aluminum cover plate for drilling with a water-soluble coating comprises the following steps:

[0055] Step S1, weighing raw materials by weight, mixing and stirring 30 parts of polyvinyl alcohol, 30 parts of polyacrylic acid, 5 parts of polyvinyl pyrrolidone, 5 parts of modified hyperbranched polyether prepared in Example 2, 0.2 parts of defoamer BYK028, and 7 parts of reinforcing filler prepared in Example 2 to obtain a water-soluble coating;

[0056] Step S2: evenly apply the water-soluble coating on the aluminum sheet to form a coating with a thickness of 0.15 mm, and dry it to obtain an aluminum cover plate for drilling with a water-soluble coating.

[0057] Example 6: A method for preparing an aluminum cover plate for drilling with a water-soluble coating comprises the following steps:

[0058] Step S1, weighing raw materials by weight, mixing and stirring 35 parts of polyvinyl alcohol, 40 parts of polyacrylic acid, 7 parts of polyvinyl pyrrolidone, 7 parts of modified hyperbranched polyether prepared in Example 3, 0.3 parts of defoamer BYK028, and 9 parts of reinforcing filler prepared in Example 3 to obtain a water-soluble coating;

[0059] Step S2: evenly apply the water-soluble coating on the aluminum sheet to form a coating with a thickness of 0.15 mm, and dry it to obtain an aluminum cover plate for drilling with a water-soluble coating.

[0060] Comparative Example 1: This comparative example is an aluminum cover plate for drilling. The difference from Example 6 is that nano-boron carbide is used instead of the reinforcing filler prepared in Example 3, and the rest are the same.

[0061] Comparative Example 2: This comparative example is an aluminum cover plate for drilling. The difference from Example 6 is that commercially available hyperbranched polyether is used instead of the modified hyperbranched polyether prepared in Example 3, and the rest are the same.

[0062] The aluminum cover plates for drilling prepared in Examples 4-6 and Comparative Examples 1-2 were subjected to performance tests:

[0063] Adhesion test: Use a grid marker to draw 10×10 1mm squares on the coating film. Apply 3M transparent tape to the grid area and quickly pull it 180° to observe whether there is any adhesive peeling on the PCB board. The adhesive is graded from 0 to 5 according to the degree of peeling. No peeling is the best grade 0, and peeling with a peeling area of ​​less than 10% is grade 1. Shedding is not less than 10% and less than 30% is grade 2. Shedding area is not less than 30% and less than 50% is grade 3. Shedding area is not less than 50% and less than 70% is grade 4. Shedding area is not less than 70% and not less than 70% is grade 5.

[0064] Water solubility test: Immerse the specimen in water for 30 minutes, take it out and dry it, and observe the surface condition. The water solubility is divided into 0 to 5 levels, where level 0 means the solubility is higher than 90% by weight, level 1 means the solubility is higher than 80% but not higher than 90% by weight, level 2 means the solubility is higher than 60% but not higher than 80% by weight, level 3 means the solubility is higher than 30% but not higher than 60% by weight, level 4 means the solubility is higher than 10% but not higher than 30% by weight, and level 5 means the solubility is not higher than 10% by weight.

[0065] Drilling test: The aluminum cover plate specimen was subjected to a 0.25 mm hole drilling test;

[0066] Heat resistance test: Place the sample in an oven at 80°C for 30 minutes and observe whether the coating surface falls off;

[0067] Thermal conductivity test: Tested according to ASTM E1530 coating thermal conductivity test standard;

[0068] The test results are shown in Table 1:

[0069] Table 1: Performance test results

[0070]

[0071] As can be seen from Table 1, the coating on the surface of the aluminum cover plate for drilling prepared by the present invention has excellent adhesion, water solubility and heat resistance. The aluminum cover plate for drilling with the coating has less roughness of the hole wall after drilling and no broken needles, and has a high thermal conductivity.

[0072] The above content is merely an example and explanation of the concept of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the scope defined by the concept of the invention, they should all fall within the scope of protection of the present invention.

Claims

1. An aluminum cover plate for drilling with a water-soluble coating, characterized in that: It includes a water-soluble coating and an aluminum sheet; the water-soluble coating is formed by coating a water-soluble paint on the surface of the aluminum sheet; The water-soluble coating comprises the following raw materials in parts by weight: 25-35 parts of polyvinyl alcohol, 20-40 parts of polyacrylic acid, 5-9 parts of reinforcing filler, 3-7 parts of polyvinyl pyrrolidone, 3-7 parts of modified hyperbranched polyether, and 0.1-0.3 parts of defoaming agent; The reinforcing filler is prepared by the following steps: Step A1, disperse nano-boron carbide evenly in a mixture of deionized water and ethanol, ultrasonicate for 0.5-1h, add 0.1mol / L hexadecyltrimethylammonium bromide and mix evenly, adjust the pH to 8-9, continue stirring for 10min, and heat to 35-45°C, then add tetraethyl orthosilicate three times, each time with an interval of 2h, and finally stir and react for 24h, filter, wash, collect the product, redisperse the product in ethanolamine ethanol solution, and reflux extract at 90°C for 12h, repeat the extraction once, filter, wash, and dry to obtain B4C@SiO2 nanomaterial; Step A2: Disperse the B4C@SiO2 nanomaterial evenly in a 1 mol / L Tris-HCl buffer solution with a pH of 8-8.5, add deionized water and ultrasonically disperse for 15-25 minutes, then heat to 30-40°C, add dopamine hydrochloride and stir to react for 5-10 hours, centrifuge, wash, and dry to obtain a reinforcing filler; The modified hyperbranched polyether is prepared by the following steps: Step B1, tris(hydroxymethyl)aminomethane and sodium hydroxide are mixed and stirred in ethanol, ethyl glycidyl ether is added and stirred for 2.5-3.5 hours, and distilled under reduced pressure, filtered, washed, and dried to obtain an ether-containing monomer; Step B2, triglycidyl isocyanurate and tetrabutylammonium bromide are mixed and stirred in N,N-dimethylformamide, and then the ether-containing monomer is added. Under nitrogen conditions, the temperature is raised to 90-100° C. and the reaction is carried out for 3.5-4.5 hours. Then, tetrahydrofuran is added and stirred for 5-10 minutes, and the mixture is washed alternately with 80° C. hot water and cold ether, filtered, and dried to obtain a hyperbranched polyether; Step B3: Mix the hyperbranched polyether and sodium hydroxide in N,N-dimethylformamide and stir evenly, then add 5-aminoisophthalic acid and stir to react for 2-4 hours, and distill under reduced pressure to obtain the modified hyperbranched polyether.

2. The aluminum cover plate for drilling with a water-soluble coating according to claim 1, characterized in that: In step A1, the usage ratio of nano boron carbide, deionized water, ethanol, hexadecyltrimethylammonium bromide, tetraethyl orthosilicate and ethanolamine ethanol solution is 2-4 g: 70 mL: 30 mL: 3-5 mL: 1.5-3 mL: 100 mL.

3. The aluminum cover plate for drilling with a water-soluble coating according to claim 2, characterized in that: The volume ratio of ethanolamine to ethanol in the ethanolamine-ethanol solution in step A1 is 1:

4.

4. The aluminum cover plate for drilling with a water-soluble coating according to claim 1, characterized in that: In step A2, the usage ratio of B4C@SiO2 nanomaterial, Tris-HCl buffer solution, deionized water and dopamine hydrochloride is 1-3 g: 5 mL: 100 mL: 0.3-0.6 g.

5. The aluminum cover plate for drilling with a water-soluble coating according to claim 1, characterized in that: In step B1, the usage ratio of tris(hydroxymethyl)aminomethane, sodium hydroxide, ethanol and ethyl glycidyl ether is 0.01-0.03 mol: 0.03-0.06 g: 50 mL: 0.012-0.033 mol.

6. The aluminum cover plate for drilling with a water-soluble coating according to claim 1, characterized in that: In step B2, the usage ratio of triglycidyl isocyanurate, tetrabutylammonium bromide, N,N-dimethylformamide, ether-containing monomer, tetrahydrofuran, hot water and cold ether is 0.01-0.03 mol: 0.0005-0.0015 mol: 100 mL: 1.5-3.5 g: 30 mL: 50 mL: 50 mL.

7. The aluminum cover plate for drilling with a water-soluble coating according to claim 1, characterized in that: In step B3, the usage ratio of the hyperbranched polyether, sodium hydroxide, N,N-dimethylformamide and 5-aminoisophthalic acid is 5-10 g: 0.1-0.8 g: 100 mL: 1-3 g.

8. The aluminum cover plate for drilling with a water-soluble coating according to claim 1, characterized in that: The defoamer is one of BYK024 and BYK028.

9. A method for preparing the aluminum cover plate for drilling with a water-soluble coating according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step S1, weighing raw materials in parts by weight, mixing and stirring polyvinyl alcohol, polyacrylic acid, polyvinyl pyrrolidone, modified hyperbranched polyether, defoaming agent and reinforcing filler to obtain a water-soluble coating; Step S2: evenly apply the water-soluble coating on the aluminum sheet to form a coating with a thickness of 0.15 mm, and dry it to obtain an aluminum cover plate for drilling with a water-soluble coating.

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