A lead-free coating applied to a resistor and a method of making the same

Abstract

The application relates to the technical field of lead-free coating, and discloses a lead-free coating applied to a resistor and a preparation method thereof. After cold pressing, ball milling and heat treatment, mixed powder is prepared from bismuth trioxide, aluminum trioxide, boron trioxide, potassium oxide and calcium fluoride. Grafted nano-silicon dioxide is prepared by grafting hyperbranched polyesters prepared from polymeric esters prepared by polymerization of acrylic acid, polyurethane and chitosan. Modified hydroxyethyl cellulose is prepared by modification of dodecylpyridine bromide. The lead-free coating prepared by the application has good explosion-proof performance, can not be cracked in the conversion process of low pressure and high pressure, the adhesion is greatly improved, the lead-free coating is not easy to fall off in the use process, the service life is prolonged, the lead-free coating has good hydrophobic performance and is easy to clean. The process is simple, harmful pollutants are not easy to be generated, and the process meets the green production requirement.

Description

Technical Field

[0001] This invention relates to the field of lead-free coating technology, specifically to a lead-free coating for resistors and its preparation method. Background Technology

[0002] Resistors are essential electrical components in circuit systems. They come in various materials, such as metal, carbon, and ceramic, and are categorized as fixed or variable. The appropriate resistor must be selected for the specific operating environment. Prolonged use of exposed resistors, especially metal ones, can lead to corrosion and aging, affecting their resistivity and causing circuit malfunctions, potentially even resulting in safety accidents. Therefore, applying a coating to the surface of resistors effectively protects the resistive element, extends its lifespan, and maintains good performance over a long period, which is beneficial to the entire industry. Summary of the Invention

[0003] (a) Technical problems to be solved

[0004] To address the shortcomings of existing technologies, this invention provides a lead-free coating for resistors and its preparation method.

[0005] (II) Technical Solution

[0006] A method for preparing a lead-free coating for use in resistors includes the following steps:

[0007] S1. Mix bismuth trioxide, aluminum trioxide, boron trioxide, potassium oxide, and calcium fluoride, and process them using a horizontal ball mill at a speed of 200~400 rpm for 1~3 h. Then, perform cold pressing at a pressure of 10~20 MPa for 2~5 min, followed by heat treatment at a temperature of 420~480℃ for 20~40 min. After processing, crush and sieve through a 100~200 mesh to obtain the mixed powder.

[0008] S2. Dissolve chitosan in a 10% (w / w) glacial acetic acid solution to prepare a chitosan solution. Add liquid polyurethane to water and stir until homogeneous to prepare a polyurethane solution. Heat the chitosan solution to 50-60°C, add the polyurethane solution, acrylic acid, ammonium persulfate initiator, and manganese ions initiator. Raise the temperature to 80-90°C and stir the reaction for 1-3 hours to obtain the product, acrylic acid polymer ester.

[0009] S3. Diethylenetriamine was placed in an ice-water bath, nitrogen gas was introduced, and acrylic acid polymer and methanol were slowly added dropwise. The reaction was carried out at 20-30℃ for 3-6 h. The solvent was removed by vacuum distillation to obtain the reaction monomer. Then, it was mixed with nano-silica and p-toluenesulfonic acid and stirred at high speed at 120-150℃ for 8-16 h under nitrogen gas. The product was washed with methanol, centrifuged at 10000-20000 r / min to precipitate, and vacuum dried to obtain grafted nano-silica.

[0010] S4. Mix hydroxyethyl cellulose and isopropanol, purge with nitrogen, slowly add benzoyl peroxide, and allow to swell for 12-24 h. Then, raise the temperature to 75-90℃, slowly add dodecylpyridine bromide, react for 3-6 h, filter and wash, neutralize to pH 7-8, and vacuum dry to obtain modified hydroxyethyl cellulose.

[0011] S5. Add the mixed powder, grafted nano-silica, and modified hydroxyethyl cellulose to deionized water, stir evenly, add aluminum dihydrogen phosphate, and ball mill for 30-60 min to prepare a lead-free coating.

[0012] Preferably, in step S1, the mass ratio of bismuth trioxide, aluminum trioxide, boron trioxide, potassium oxide, and calcium fluoride is 1:0.8~1.2:0.8~1.2:0.2~0.4:0.1~0.3.

[0013] Preferably, in step S2, the mass ratio of chitosan, liquid polyurethane, acrylic acid, ammonium persulfate, and manganese ions is 1:2~4:0.6~1:0.1~0.3:0.1~0.3.

[0014] Preferably, in step S3, the mass ratio of diethylenetriamine, acrylate, methanol, nano silica, and p-toluenesulfonic acid is 1:0.8~1.2:1.5~2.5:1~1.5:0.05~0.12.

[0015] Preferably, in step S4, the mass ratio of hydroxyethyl cellulose, isopropanol, benzoyl peroxide, and dodecyl pyridine bromide is 1:0.6~0.8:0.05~0.2:0.6~0.8.

[0016] Preferably, in step S5, the mass ratio of the mixed powder, grafted nano-silica, modified hydroxyethyl cellulose, deionized water, and aluminum dihydrogen phosphate is 1:0.2~0.4:0.6~0.8:1.2~2.5:0.1~0.3.

[0017] Preferably, the lead-free coating is applied to various types of resistors.

[0018] Preferably, a lead-free coating is evenly applied to the surface of the resistor, and after coating, it is subjected to a heat curing treatment at 200~500℃ for 1~3 hours.

[0019] (iii) Beneficial technical effects

[0020] The lead-free coating of this invention is made from bismuth trioxide, aluminum trioxide, boron trioxide, potassium oxide, calcium fluoride, grafted nano-silica, modified hydroxyethyl cellulose, aluminum dihydrogen phosphate, and deionized water. Bismuth trioxide, aluminum trioxide, boron trioxide, potassium oxide, and calcium fluoride are mixed into a powder through cold pressing, ball milling, and heat treatment. The grafted nano-silica is obtained by grafting onto a hyperbranched polymer ester obtained from a polymer ester synthesized from acrylic acid, polyurethane, and chitosan. The modified hydroxyethyl cellulose is prepared by modification with dodecylpyridine bromide.

[0021] The lead-free coating obtained by this invention has excellent explosion-proof performance, preventing cracking during low-pressure to high-pressure transitions. Simultaneously, its adhesion is significantly improved, making it less prone to peeling during use and extending its service life. Furthermore, it exhibits good hydrophobic properties and is easy to clean. The process of this invention is simple, does not generate harmful pollutants, and meets the requirements of green production. Detailed Implementation

[0022] Example 1: S1. Mix 10 kg of bismuth trioxide, 8 kg of aluminum trioxide, 8 kg of boron trioxide, 2 kg of potassium oxide, and 1 kg of calcium fluoride. Then, use a horizontal ball mill at 200 rpm for 1 h, followed by cold pressing at 10 MPa for 2 min, and then heat treatment at 420℃ for 20 min. After the treatment, crush and sieve through a 100-mesh sieve to obtain the mixed powder.

[0023] S2. Dissolve 5 kg of chitosan in 30 L of 10% glacial acetic acid solution to prepare a chitosan solution. Add 10 kg of liquid polyurethane to 30 L of water and stir until homogeneous to prepare a polyurethane solution. Heat the chitosan solution to 50°C, add the polyurethane solution, 3 kg of acrylic acid, 0.5 kg of ammonium persulfate initiator, and 0.5 kg of manganese ions initiator. Raise the temperature to 80°C and stir for 1 h to obtain the product, acrylic acid polymer ester.

[0024] S3. Place 10 kg of diethylenetriamine in an ice-water bath, purge with nitrogen, and slowly add 8 kg of acrylic acid polymer and 15 kg of methanol. React at 20 °C for 3 h. Remove the solvent by vacuum distillation to obtain the reactant monomer. Then mix it with 10 kg of nano-silica and 0.5 kg of p-toluenesulfonic acid, and stir at high speed at 120 °C for 8 h under nitrogen. Wash the product with methanol, centrifuge at 10000 r / min to precipitate, and vacuum dry to obtain grafted nano-silica.

[0025] S4. Mix 10 kg of hydroxyethyl cellulose and 6 kg of isopropanol, purge with nitrogen, slowly add 0.5 kg of benzoyl peroxide, allow to swell for 12 h, then heat to 75 °C, slowly add 6 kg of dodecylpyridine bromide, react for 3 h, filter, wash, neutralize to pH 7, and vacuum dry to obtain modified hydroxyethyl cellulose.

[0026] S5. Add 10 kg of mixed powder, 2 kg of grafted nano silica, and 6 kg of modified hydroxyethyl cellulose to 12 kg of deionized water, stir evenly, add 1 kg of aluminum dihydrogen phosphate, and ball mill for 30 min to prepare a lead-free coating.

[0027] Example 2: S1. Mix 10 kg of bismuth trioxide, 12 kg of aluminum trioxide, 12 kg of boron trioxide, 4 kg of potassium oxide, and 3 kg of calcium fluoride. Then, use a horizontal ball mill at 400 rpm for 3 hours. Perform cold pressing at 20 MPa for 5 minutes, followed by heat treatment at 480℃ for 40 minutes. After the treatment, crush and sieve through a 200-mesh screen to obtain the mixed powder.

[0028] S2. Dissolve 5 kg of chitosan in 60 L of 10% glacial acetic acid solution to prepare a chitosan solution. Add 20 kg of liquid polyurethane to 60 L of water and stir until homogeneous to prepare a polyurethane solution. Heat the chitosan solution to 60°C, add the polyurethane solution, 5 kg of acrylic acid, 1.5 kg of ammonium persulfate initiator, and 1.5 kg of manganese ions initiator. Raise the temperature to 90°C and stir for 3 h to obtain the product, acrylic acid polymer ester.

[0029] S3. Place 10 kg of diethylenetriamine in an ice-water bath, purge with nitrogen, and slowly add 12 kg of acrylic acid polymer and 25 kg of methanol. React at 30 °C for 6 h. Remove the solvent by vacuum distillation to obtain the reactant monomer. Then mix it with 15 kg of nano-silica and 1.2 kg of p-toluenesulfonic acid, and stir at 150 °C for 16 h under nitrogen. Wash the product with methanol, centrifuge at 20,000 r / min to precipitate, and vacuum dry to obtain grafted nano-silica.

[0030] S4. Mix 10 kg of hydroxyethyl cellulose and 8 kg of isopropanol, purge with nitrogen, slowly add 2 kg of benzoyl peroxide, allow to swell for 24 h, then heat to 90 °C, slowly add 8 kg of dodecylpyridine bromide, react for 6 h, filter, wash, neutralize to pH 8, and vacuum dry to obtain modified hydroxyethyl cellulose.

[0031] S5. Add 10 kg of mixed powder, 4 kg of grafted nano silica, and 8 kg of modified hydroxyethyl cellulose to 25 kg of deionized water, stir evenly, add 3 kg of aluminum dihydrogen phosphate, and ball mill for 60 min to prepare a lead-free coating.

[0032] Example 3: S1. Mix 10 kg of bismuth trioxide, 9 kg of aluminum trioxide, 10 kg of boron trioxide, 3 kg of potassium oxide, and 2 kg of calcium fluoride. Then, use a horizontal ball mill at 300 rpm for 1.5 h, followed by cold pressing at 12 MPa for 3 min, and then heat treatment at 450℃ for 30 min. After the treatment, crush and sieve through a 120-mesh screen to obtain the mixed powder.

[0033] S2. Dissolve 5 kg of chitosan in 40 L of 10% glacial acetic acid solution to prepare a chitosan solution. Add 12 kg of liquid polyurethane to 4 L of water and stir until homogeneous to prepare a polyurethane solution. Heat the chitosan solution to 55°C, add the polyurethane solution, 3.5 kg of acrylic acid, 0.8 kg of ammonium persulfate initiator, and 0.6 kg of manganese ions initiator. Raise the temperature to 90°C and stir for 2 h to obtain the product, acrylic acid polymer ester.

[0034] S3. Place 10 kg of diethylenetriamine in an ice-water bath, purge with nitrogen, and slowly add 10 kg of acrylic acid polymer and 18 kg of methanol. React at 25 °C for 4 h. Remove the solvent by vacuum distillation to obtain the reactant monomer. Then mix it with 12 kg of nano-silica and 0.6 kg of p-toluenesulfonic acid, and stir at 130 °C for 10 h under nitrogen. Wash the product with methanol, centrifuge at 15000 r / min to precipitate, and vacuum dry to obtain grafted nano-silica.

[0035] S4. Mix 10 kg of hydroxyethyl cellulose and 6.5 kg of isopropanol, purge with nitrogen, slowly add 0.9 kg of benzoyl peroxide, allow to swell for 15 h, then heat to 80 °C and slowly add 6.2 kg of dodecylpyridine bromide. React for 4 h, filter and wash, neutralize to pH 8, and vacuum dry to obtain modified hydroxyethyl cellulose.

[0036] S5. Add 10 kg of mixed powder, 2.5 kg of grafted nano silica, and 7.2 kg of modified hydroxyethyl cellulose to 18 kg of deionized water, stir evenly, add 1.2 kg of aluminum dihydrogen phosphate, and ball mill for 50 min to prepare a lead-free coating.

[0037] Example 5: S1. Mix 10 kg of bismuth trioxide, 10.3 kg of aluminum trioxide, 11.5 kg of boron trioxide, 3.5 kg of potassium oxide, and 2.2 kg of calcium fluoride. Then, use a horizontal ball mill at 300 rpm for 2.5 h, followed by cold pressing at 16 MPa for 5 min, and then heat treatment at 460℃ for 30 min. After the treatment, crush and sieve through a 160-mesh screen to obtain a mixed powder.

[0038] S2. Dissolve 5 kg of chitosan in 50 L of 10% glacial acetic acid solution to prepare a chitosan solution. Add 18 kg of liquid polyurethane to 45 L of water and stir until homogeneous to prepare a polyurethane solution. Heat the chitosan solution to 50°C, add the polyurethane solution, 4.5 kg of acrylic acid, 1 kg of ammonium persulfate initiator, and 1 kg of manganese ions initiator. Raise the temperature to 80°C and stir for 1.5 h to obtain the product, acrylic acid polymer ester.

[0039] S3. Place 10 kg of diethylenetriamine in an ice-water bath, purge with nitrogen, and slowly add 10.5 kg of acrylic acid polymer and 20 kg of methanol. React at 30 °C for 5 h. Remove the solvent by vacuum distillation to obtain the reactant monomer. Then mix it with 14 kg of nano-silica and 0.9 kg of p-toluenesulfonic acid, and stir at 140 °C for 15 h under nitrogen. Wash the product with methanol, centrifuge at 18000 r / min to precipitate, and vacuum dry to obtain grafted nano-silica.

[0040] S4. Mix 10 kg of hydroxyethyl cellulose and 7.5 kg of isopropanol, purge with nitrogen, slowly add 1.2 kg of benzoyl peroxide, allow to swell for 20 h, then heat to 80 °C, slowly add 7.5 kg of dodecylpyridine bromide, react for 5 h, filter, wash, neutralize to pH 7, and vacuum dry to obtain modified hydroxyethyl cellulose.

[0041] S5. Add 10 kg of mixed powder, 3.5 kg of grafted nano silica, and 7.5 kg of modified hydroxyethyl cellulose to 20 kg of deionized water, stir evenly, add 2.5 kg of aluminum dihydrogen phosphate, and ball mill for 50 min to prepare a lead-free coating.

[0042] Example 5: S1. Mix 10 kg of bismuth trioxide, 11.2 kg of aluminum trioxide, 10.5 kg of boron trioxide, 3.5 kg of potassium oxide, and 2.3 kg of calcium fluoride. Then, use a horizontal ball mill at 350 rpm for 3 h, followed by cold pressing at 20 MPa for 5 min, and then heat treatment at 460℃ for 40 min. After the treatment, crush and sieve through a 200-mesh screen to obtain a mixed powder.

[0043] S2. Dissolve 5 kg of chitosan in 45 L of 10% glacial acetic acid solution to prepare a chitosan solution. Add 20 kg of liquid polyurethane to 30 L of water and stir until homogeneous to prepare a polyurethane solution. Heat the chitosan solution to 60°C, add the polyurethane solution, 4 kg of acrylic acid, 1.3 kg of ammonium persulfate initiator, and 1.2 kg of manganese ions initiator. Raise the temperature to 90°C and stir for 3 h to obtain the product, acrylic acid polymer ester.

[0044] S3. Place 10 kg of diethylenetriamine in an ice-water bath, purge with nitrogen, and slowly add 10.2 kg of acrylic acid polymer and 22 kg of methanol. React at 30 °C for 5 h. Remove the solvent by vacuum distillation to obtain the reactant monomer. Then mix it with 15 kg of nano-silica and 0.5 kg of p-toluenesulfonic acid, and stir at high speed at 150 °C for 15 h under nitrogen. Wash the product with methanol, centrifuge at 20,000 r / min to precipitate, and vacuum dry to obtain grafted nano-silica.

[0045] S4. Mix 10 kg of hydroxyethyl cellulose and 8 kg of isopropanol, purge with nitrogen, slowly add 0.5 kg of benzoyl peroxide, allow to swell for 24 h, then heat to 90 °C, slowly add 8 kg of dodecylpyridine bromide, react for 3 h, filter, wash, neutralize to pH 7, and vacuum dry to obtain modified hydroxyethyl cellulose.

[0046] S5. Add 10 kg of mixed powder, 3 kg of grafted nano silica, and 8 kg of modified hydroxyethyl cellulose to 15 kg of deionized water, stir evenly, add 2 kg of aluminum dihydrogen phosphate, and ball mill for 50 min to prepare a lead-free coating.

[0047] Comparative Example 1: 5 kg of aluminum dihydrogen phosphate was added to 8 kg of deionized water, stirred evenly, and ball-milled for 30 min to form a coating.

[0048] Test Example 1: Overvoltage Test

[0049] Test Method: Starting with 220 V AC and maintaining it for 1 minute, rapidly increase the voltage to 270 V (the center voltage between the starting voltage and the maximum permissible AC voltage of 320 V) within 2 seconds and maintain it for 1 minute. Then, rapidly increase the voltage to the maximum permissible AC voltage of 320 V within 2 seconds and maintain it for 2 minutes. Next, increase the voltage at a rate of 10 V every 30 seconds until the varistor fails the test, and observe for sparking, burning, or explosion of the varistor. The fuse is a 5 A slow-speed type. If the varistor shows sparking, burning, or explosion, the overvoltage test is considered failed and marked "X"; if the varistor does not show sparking, burning, or explosion, the overvoltage test is considered passed and marked "O" in Table 3 below.

[0050] Table 1

[0051]

[0052] As shown in Table 1, the lead-free coatings of Examples 1 to 5 have good explosion-proof properties and can withstand instantaneous voltage without producing sparks or causing combustion engine explosions.

[0053] Test Example 2: Adhesion Test

[0054] Test method: The cross-marking method was used as the test method. According to GB / T9286-2021, the coatings prepared in Examples 1 to 5 and Comparative Example 1 were coated on a carbon steel plate of 200 mm × 200 mm × 10 mm for testing. A 6×6 cutting method was used. Three parts of the coating of each sample were selected to make cut samples. The overall situation was observed. The adhesion index of the coating was evaluated according to the standard. The results are shown in Table 2.

[0055] Table 2

[0056]

[0057] As shown in Table 2, the coatings of Examples 1 to 5 have good adhesion and are not easy to peel off.

[0058] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a lead-free coating for use in resistors, characterized in that, Includes the following steps: S1. Mix bismuth trioxide, aluminum trioxide, boron trioxide, potassium oxide, and calcium fluoride, and process them using a horizontal ball mill at a speed of 200~400 rpm for 1~3 h. Then, perform cold pressing at a pressure of 10~20 MPa for 2~5 min, followed by heat treatment at a temperature of 420~480℃ for 20~40 min. After processing, crush and sieve through a 100~200 mesh to obtain the mixed powder. S2. Dissolve chitosan in a 10% (w / w) glacial acetic acid solution to prepare a chitosan solution. Add liquid polyurethane to water and stir until homogeneous to prepare a polyurethane solution. Heat the chitosan solution to 50-60°C, add the polyurethane solution, acrylic acid, ammonium persulfate initiator, and manganese ions initiator. Raise the temperature to 80-90°C and stir the reaction for 1-3 hours to obtain the product, acrylic acid polymer ester. S3. Diethylenetriamine was placed in an ice-water bath, nitrogen gas was introduced, and acrylic acid polymer and methanol were slowly added dropwise. The reaction was carried out at 20-30℃ for 3-6 h. The solvent was removed by vacuum distillation to obtain the reaction monomer. Then, it was mixed with nano-silica and p-toluenesulfonic acid and stirred at high speed at 120-150℃ for 8-16 h under nitrogen gas. The product was washed with methanol, centrifuged at 10000-20000 r / min to precipitate, and vacuum dried to obtain grafted nano-silica. S4. Mix hydroxyethyl cellulose and isopropanol, purge with nitrogen, slowly add benzoyl peroxide, and allow to swell for 12-24 h. Then, raise the temperature to 75-90℃, slowly add dodecylpyridine bromide, react for 3-6 h, filter and wash, neutralize to pH 7-8, and vacuum dry to obtain modified hydroxyethyl cellulose. S5. Add the mixed powder, grafted nano-silica, and modified hydroxyethyl cellulose to deionized water, stir evenly, add aluminum dihydrogen phosphate, and ball mill for 30-60 min to prepare a lead-free coating.

2. The method for preparing a lead-free coating for a resistor according to claim 1, characterized in that: In step S1, the mass ratio of bismuth trioxide, aluminum trioxide, boron trioxide, potassium oxide, and calcium fluoride is 1:0.8~1.2:0.8~1.2:0.2~0.4:0.1~0.

3.

3. The method for preparing a lead-free coating for a resistor according to claim 1, characterized in that: In step S2, the mass ratio of chitosan, liquid polyurethane, acrylic acid, ammonium persulfate, and manganese ions is 1:2~4:0.6~1:0.1~0.3:0.1~0.

3.

4. The method for preparing a lead-free coating for a resistor according to claim 1, characterized in that: In step S3, the mass ratio of diethylenetriamine, acrylate, methanol, nano silica, and p-toluenesulfonic acid is 1:0.8~1.2:1.5~2.5:1~1.5:0.05~0.

12.

5. The method for preparing a lead-free coating for a resistor according to claim 1, characterized in that: In step S4, the mass ratio of hydroxyethyl cellulose, isopropanol, benzoyl peroxide, and dodecyl pyridine bromide is 1:0.6~0.8:0.05~0.2:0.6~0.

8.

6. The method for preparing a lead-free coating for a resistor according to claim 1, characterized in that: In step S5, the mass ratio of the mixed powder, grafted nano-silica, modified hydroxyethyl cellulose, deionized water, and aluminum dihydrogen phosphate is 1:0.2~0.4:0.6~0.8:1.2~2.5:0.1~0.

3.

7. The application of a lead-free coating prepared by the method for preparing a lead-free coating for a resistor as described in claim 1, characterized in that: Application of the lead-free coating on various resistors.

8. The application of the lead-free coating according to claim 7, characterized in that, Apply a lead-free coating evenly to the surface of the resistor. After coating, perform a heat curing treatment at 200~500℃ for 1~3 hours.

Images