Drilling aluminum cover plate with water-soluble coating and preparation method of drilling aluminum cover plate

Abstract

The invention relates to the technical field of aluminum cover plates for drilling, and discloses an aluminum cover plate with a water-soluble coating for drilling and a preparation method of the aluminum cover plate. The prepared aluminum cover plate for drilling is prepared by taking an aluminum sheet as a base material and coating the surface of the aluminum sheet with a water-soluble coating; the water-soluble paint is prepared from the following raw materials in parts by weight: 25 to 35 parts of polyvinyl alcohol, 20 to 40 parts of polyacrylic acid, 8 to 15 parts of reinforcing filler, 3 to 7 parts of polyvinylpyrrolidone, 3 to 7 parts of modified hyperbranched polyether and 0.1 to 0.3 part of defoaming agent; the coating has excellent adhesive force, heat dissipation performance and heat resistance on the surface of an aluminum sheet and has good plastic deformation capacity, and the aluminum cover plate can have the longer service life.

Description

Technical Field

[0001] The 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] PCB boards are widely used in medical equipment, industrial equipment, communication equipment, automotive electronics, household appliances and other fields. The drilling process is extremely important in the manufacturing process of PCB. In order to protect the PCB board and improve the quality of drilling, it is often necessary to put a layer of cover material. This board placed on the processed copper clad board is called a "cover". The "cover" materials mainly include phenolic resin board, epoxy glass cloth board, ordinary aluminum foil board, resin-coated aluminum-based cover, etc. Among them, compared with other cover, the resin-coated aluminum-based cover has many unique advantages. It can not only effectively improve the quality of the drilled hole and extend the service life of the drill bit, but also can be used in drilling operations with increased number of stacked boards, greatly improving the efficiency of drilling.

[0003] However, during the PCB drilling process, the drill bit will generate a lot of heat. If this heat cannot be dissipated in time, the drill bit temperature will rise, which will affect the drilling accuracy and the life of the drill bit. Therefore, the water-soluble coating on the surface of the aluminum cover plate needs to have good thermal conductivity so that it can quickly take away the heat generated by the drill bit during drilling, reduce the temperature of the drill bit, protect the drill bit and ensure the drilling accuracy. In addition, it is also necessary to have lubrication, buffering and other 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 coating 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: Prepare nano boron carbide (B 4C) Disperse uniformly in a mixture of deionized water and ethanol, ultrasonically treat for 0.5-1h, add 0.1mol / L hexadecyltrimethylammonium bromide and stir uniformly, 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, 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 B 4 C@SiO 2 Nanomaterials;

[0011] Step A2: B 4 C@SiO 2 The nanomaterial is dispersed uniformly in a 1 mol / L Tris-HCl buffer solution with a pH of 8-8.5, and then deionized water is added for ultrasonic dispersion for 15-25 minutes, and then the temperature is raised to 30-40° C., dopamine hydrochloride is added, stirred and reacted for 5-10 hours, and then centrifuged, washed and dried to obtain a reinforced filler;

[0012] Further, 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] Further, in step A1, the volume ratio of ethanolamine to ethanol in the ethanolamine ethanol solution is 1:4;

[0014] Furthermore, in step A2, B 4 C@SiO 2 The dosage ratio of the 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 2.5-3.5h, 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, and the temperature is raised to 90-100° C. under nitrogen conditions to react for 3.5-4.5 hours, and 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] Further, 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;

[0020] Further, 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;

[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 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, uniformly coating the water-soluble coating on the aluminum sheet to form a coating with a thickness of 0.15 mm, and drying the coating 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 prepared by coating a water-soluble coating on the surface of an aluminum sheet with an aluminum sheet as a substrate; the water-soluble coating has good plastic deformation ability on the surface of the aluminum sheet, and can make the aluminum cover plate have a longer service life. In addition, the water-soluble coating uses polyvinyl alcohol and polyacrylic acid with good water solubility as raw materials, and adds polyvinyl pyrrolidone, modified hyperbranched polyether and enhanced coating to improve the adhesion, heat dissipation and heat resistance of the coating while maintaining water solubility.

[0027] In the reinforcing filler, hexadecyl trimethyl ammonium bromide was used as a template and tetraethyl orthosilicate was used as a raw material to synthesize mesoporous silica on the surface of boron carbide to obtain B 4 C@SiO 2 Nanomaterials; dopamine hydrochloride is used as raw material, in B 4C@SiO 2 Polydopamine is synthesized on the surface of nanomaterials to produce reinforcing fillers. The reinforcing fillers introduced into the coating can promote heat transfer, improve the heat dissipation effect of the coating, reduce the entanglement of the metal wire caused by the high heat of the drill bit during drilling, and thus improve the quality and efficiency of drilling; it can also improve the plastic deformation ability of the coating, ensure that the coating can adapt to the cutting of the drill bit during drilling, reduce the risk of drill bit breakage and falling off, and at the same time enable the coating to better adapt to the friction and shear force generated during the drilling process, thereby ensuring the integrity and uniformity of the coating; in addition, the polydopamine layer coated on the surface of the reinforcing filler also has a catechol structure, which has excellent adhesion, can improve the adhesion of the coating to the aluminum sheet, reduce the occurrence of coating cracking during drilling, and increase the service life of the aluminum sheet.

[0028] In the modified hyperbranched polyether, trihydroxymethylaminomethane and ethyl glycidyl ether are first reacted to obtain 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 obtain a modified hyperbranched polyether. The modified hyperbranched polyether has a highly branched three-dimensional structure, which allows a large number of holes to exist inside the molecule, making it easier for heat to be transferred through these holes, 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, so that the coating on the surface of the aluminum sheet can withstand a higher temperature drilling environment, and the coating is not easy to deform and fall off; in addition, the active groups (carboxyl and hydroxyl) at the ends of the modified hyperbranched polyether can also react chemically with the oxides on the surface of the aluminum sheet to form stable chemical bonds. This bonding action allows the coating to have better bonding strength on the surface of the aluminum sheet, thereby improving the service life of the aluminum sheet. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

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

[0031] Step A1: 2 g of nano boron carbide (B 4C) Disperse evenly in a mixture of 70 mL of deionized water and 30 mL of ethanol, treat with ultrasound for 0.5 h, add 3 mL of 0.1 mol / L hexadecyltrimethylammonium bromide and stir evenly, adjust the pH to 8, continue stirring for 10 min, and heat to 35 ° C, then add 1.5 mL of tetraethyl orthosilicate three times, each time with an interval of 2 h, and finally stir and react for 24 h, filter, wash, collect the product, and redisperse the product in 100 mL of ethanolamine ethanol solution, and reflux extract at 90 ° C for 12 h, repeat the extraction once, filter, wash, and dry to obtain B 4 C@SiO 2 Nanomaterials, the volume ratio of ethanolamine to ethanol in the ethanolamine ethanol solution is 1:4;

[0032] Step A2, 1g B 4 C@SiO 2 The nanomaterial was evenly dispersed in 5 mL of 1 mol / L Tris-HCl buffer solution with a pH of 8, and then 100 mL of deionized water was added for ultrasonic dispersion for 15 min. The temperature was then raised to 30° C., 0.3 g of dopamine hydrochloride was added, stirred and reacted for 5 h, and the reinforced filler was obtained by centrifugation, washing and drying.

[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, and 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, and the temperature was raised to 90° C. under nitrogen conditions for reaction for 3.5 hours, and then 30 mL of tetrahydrofuran was added and stirred for 5 minutes, and 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 the mixture was 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: 3 g of nano boron carbide (B 4C) Disperse evenly in a mixture of 70 mL of deionized water and 30 mL of ethanol, treat with ultrasound for 0.8 h, add 4 mL of 0.1 mol / L hexadecyltrimethylammonium bromide and stir evenly, adjust the pH to 8.5, continue stirring for 10 min, and heat to 40°C, then add 2.2 mL of tetraethyl orthosilicate three times, each time with an interval of 2 h, and finally stir and react for 24 h, filter, wash, collect the product, redisperse the product in 100 mL of ethanolamine ethanol solution, and reflux extract at 90°C for 12 h, repeat the extraction once, filter, wash, and dry to obtain B 4 C@SiO 2 Nanomaterials, the volume ratio of ethanolamine to ethanol in the ethanolamine ethanol solution is 1:4;

[0039] Step A2: 2gB 4 C@SiO 2 The nanomaterial was evenly dispersed in 5 mL of 1 mol / L Tris-HCl buffer solution with a pH of 8.3, and then 100 mL of deionized water was added for ultrasonic dispersion for 20 min. The temperature was then raised to 35° C., 0.45 g of dopamine hydrochloride was added, stirred and reacted for 7 h, and the reinforced filler was obtained by centrifugation, washing and drying.

[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, and 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, and the temperature was raised to 95° C. under nitrogen conditions for reaction for 4 h, and then 30 mL of tetrahydrofuran was added and stirred for 7.5 min, and 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 the mixture was distilled under reduced pressure to obtain the modified hyperbranched polyether.

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

[0045] Step A1: 4 g of nano boron carbide (B 4C) Disperse evenly in a mixture of 70 mL of deionized water and 30 mL of ethanol, treat with ultrasound for 1 h, add 5 mL of 0.1 mol / L hexadecyltrimethylammonium bromide and stir evenly, adjust the pH to 9, continue stirring for 10 min, and heat to 45 ° C, then add 3 mL of tetraethyl orthosilicate three times, each time with an interval of 2 h, and finally stir and react for 24 h, filter, wash, collect the product, and redisperse the product in 100 mL of ethanolamine ethanol solution, and reflux extract at 90 ° C for 12 h, repeat the extraction once, filter, wash, and dry to obtain B 4 C@SiO 2 Nanomaterials, the volume ratio of ethanolamine to ethanol in the ethanolamine ethanol solution is 1:4;

[0046] Step A2: 3gB 4 C@SiO 2 The nanomaterial was evenly dispersed in 5 mL of 1 mol / L Tris-HCl buffer solution with a pH of 8.5, and then 100 mL of deionized water was added for ultrasonic dispersion for 25 min. The temperature was then raised to 40° C., 0.6 g of dopamine hydrochloride was added, stirred and reacted for 10 h, and the reinforced filler was obtained by centrifugation, washing and drying.

[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 h, 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, and the temperature was raised to 100 ° C under nitrogen conditions for reaction for 4.5 hours, and then 30 mL of tetrahydrofuran was added and stirred for 10 minutes, and 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 the mixture was 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 modified hyperbranched polyether prepared in Example 1, 0.1 parts of defoamer BYK024 and 5 parts of reinforcing filler prepared in Example 1 to obtain a water-soluble coating;

[0053] Step S2, uniformly coating the water-soluble coating on the aluminum sheet to form a coating with a thickness of 0.15 mm, and drying the coating 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, uniformly coating the water-soluble coating on the aluminum sheet to form a coating with a thickness of 0.15 mm, and drying the coating 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, uniformly coating the water-soluble coating on the aluminum sheet to form a coating with a thickness of 0.15 mm, and drying the coating 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 is 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 is 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 cutter to draw 10×10 1mm squares on the coating film, stick 3M special transparent tape on the grid area, pull it 180° quickly, and observe whether there is any glue falling off on the PCB board; it is divided into 0 to 5 levels according to the shedding situation, with no shedding phenomenon as the best level 0, shedding with shedding area less than 10% as level 1, shedding of not less than 10% and less than 30% as level 2, shedding area not less than 30% and less than 50% as level 3, shedding area not less than 50% and less than 70% as level 4, and shedding area not less than 70% as level 5;

[0064] Water solubility test: immerse the specimen in water for 30 minutes, take it out and dry it, and observe the surface condition of the board. It is divided into 0 to 5 levels according to the water solubility, with level 0 being a dissolution weight higher than 90%, level 1 being a dissolution weight higher than 80% and not higher than 90%, level 2 being a dissolution weight higher than 60% and not higher than 80%, level 3 being a dissolution weight higher than 30% and not higher than 60%, level 4 being a dissolution weight higher than 10% and not higher than 30%, and level 5 being a dissolution weight not higher than 10%;

[0065] Drilling test: The aluminum cover plate specimen is 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: According to ASTM E1530 coating thermal conductivity test standard test;

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

[0069] Table 1: Performance test results

[0070]

[0071] It can be seen from Table 1 that 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 higher thermal conductivity.

[0072] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described 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 protection scope of the present invention.

Claims

1. An aluminum cover plate for drilling with a water-soluble coating, characterized in that: It 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; 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, ultrasonically treat for 0.5-1h, add 0.1mol / L hexadecyltrimethylammonium bromide and mix and stir 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, 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 for ultrasonic dispersion for 15-25 min, then heat to 30-40° C., add dopamine hydrochloride and stir to react for 5-10 h, centrifuge, wash and dry to obtain a reinforced filler.

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 dosage ratio of B4C@SiO2 nanomaterial, Tris-HCl buffer solution, deionized water and dopamine hydrochloride is 1-3g:5mL:100mL:0.3-0.6g.

5. The aluminum cover plate for drilling with a water-soluble coating according to claim 1, characterized in that: 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 2.5-3.5h, 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, and the temperature is raised to 90-100° C. under nitrogen conditions to react for 3.5-4.5 hours, and 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, the hyperbranched polyether and sodium hydroxide are mixed and stirred in N,N-dimethylformamide, and then 5-aminoisophthalic acid is added and stirred to react for 2-4 hours, and distilled under reduced pressure to obtain the modified hyperbranched polyether.

6. The aluminum cover plate for drilling with a water-soluble coating according to claim 5, 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.

7. The aluminum cover plate for drilling with a water-soluble coating according to claim 5, 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.

8. The aluminum cover plate for drilling with a water-soluble coating according to claim 5, 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.

9. 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.

10. A method for preparing the aluminum cover plate for drilling with a water-soluble coating according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step S1, weighing raw materials 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, uniformly coating the water-soluble coating on the aluminum sheet to form a coating with a thickness of 0.15 mm, and drying the coating to obtain an aluminum cover plate for drilling with a water-soluble coating.

Images