Preparation method of epoxy-modified silicone resin composite coating on the surface of (Ce, Nd)-Fe-B magnet

Abstract

The present invention discloses a preparation method of an epoxy-modified silicone resin composite coating on the surface of a (Ce, Nd)-Fe-B magnet, comprising the following preparation method: step S1: preparation of an epoxy-modified silicone resin; more specifically: treating bisphenol A epoxy resin to obtain an epoxy-modified silicone resin; step S2: electrophoretic liquid configuration; more specifically: mixing a color paste, a mixed resin and deionized water to prepare an electrophoretic liquid; step S3: electrophoretic pretreatment; more specifically: subjecting the (Ce, Nd)-Fe-B magnet to an acid wash activation treatment. The present invention has a simple method for preparing an epoxy-modified silicone resin, an easy-to-implement reaction environment, and improves the poor compatibility of epoxy resin and silicone resin, and the full reaction process is green and environmentally friendly. The present invention utilizes an aqueous epoxy emulsion to react with a methylphenyl silicone resin, and the obtained mixed resin can be prepared into an electrophoretic liquid with an electrophoretic slurry and water, and a coating is prepared on the surface of a cerium-neodymium-iron-boron magnet by a cathode electrophoretic deposition method.

Description

Technical Field

[0001] The present invention relates to the technical field of composite coating preparation methods, and more specifically, to a preparation method of an epoxy-modified organic silicon resin composite coating on the surface of a (Ce, Nd)-Fe-B magnet. Background Art

[0002] Cerium-NdFeB has excellent magnetic properties and low cost, and has been widely used in various industrial sectors such as electroacoustics, electronics, aerospace, etc. However, due to its multi-phase structure and the large potential difference between the phases, it is prone to corrosion and failure, which is a major reason for the limited development and application of it.

[0003] Currently, effective corrosion protection methods for cerium-neodymium-iron-boron magnets, both domestically and internationally, primarily fall into two categories: alloying and surface protection. While alloying improves the magnet's corrosion resistance, it also affects its magnetic properties. The high cost of alloying elements also limits its application. Therefore, surface protection treatment is currently the most widely used method. Organic coatings, as a modern surface treatment technology, are the most convenient, direct, and cost-effective corrosion protection method. They are applicable to both new and in-service equipment and components, making them widely used across various industrial sectors. Silicone materials, a semi-inorganic, semi-organic polymer compound, combine the properties and functions of both inorganic and organic materials. They not only possess the excellent weather resistance, oxidation resistance, electrical insulation, flame retardancy, water absorption, and corrosion resistance of inorganic silica, but also offer the ease of processing of organic polymers, allowing them to be tailored to meet diverse application requirements. However, the high cost, poor mechanical properties, and difficulty in fully curing of pure silicone resins significantly limit their industrial application. Epoxy resin has attracted widespread attention due to its advantages such as low price, simple preparation, good chemical stability and environmental friendliness. However, due to the volatilization of some solvents in epoxy coatings during the curing process, microporous defects are easily formed, leading to the rapid intrusion of external corrosive media. In addition, the corrosion resistance of water-based epoxy resin itself is relatively poor, which greatly limits its industrial application.

[0004] Therefore, we proposed a method for preparing epoxy-modified silicone resin composite coating on the surface of (Ce, Nd)-Fe-B magnet to solve the above problems. Summary of the Invention

[0005] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides a method for preparing an epoxy-modified silicone resin composite coating on the surface of a (Ce, Nd)-Fe-B magnet to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a method for preparing an epoxy-modified silicone resin composite coating on the surface of a (Ce, Nd)-Fe-B magnet, comprising the following preparation methods:

[0007] Step S1: Preparation of epoxy-modified silicone resin;

[0008] More specifically:

[0009] The bisphenol A epoxy resin is treated to obtain an epoxy-modified silicone resin;

[0010] Step S2: preparing electrophoresis fluid;

[0011] More specifically:

[0012] The color paste, mixed resin and deionized water are mixed to prepare an electrophoresis solution;

[0013] Step S3: electrophoresis pre-treatment;

[0014] More specifically:

[0015] The (Ce, Nd)-Fe-B magnet is cleaned and dried;

[0016] Step S4: electrophoresis treatment;

[0017] More specifically:

[0018] The (Ce, Nd)-Fe-B magnet is placed in the electrophoresis solution for treatment;

[0019] Step S5: coating curing;

[0020] More specifically:

[0021] The (Ce, Nd)-Fe-B magnet after electrophoresis is heated and solidified.

[0022] In a preferred embodiment, step S1 includes activating bisphenol A epoxy resin at high temperature for 10 min-30 min, the activation temperature of bisphenol A epoxy resin is 70° C.-100° C., and the pH is adjusted to 7.5-9 using a dilute HCl solution.

[0023] In a preferred embodiment, step S1 further comprises mixing the activated bisphenol A epoxy resin and methylphenyl silicone resin, adding phosphoric acid, and stirring for 20 min to 40 min to obtain epoxy-modified silicone resin.

[0024] In a preferred embodiment, in step S1, the mixing ratio of the activated bisphenol A epoxy resin and the silicone resin is 1:1-6:1, and the phosphoric acid is 0.04g-0.1g.

[0025] In a preferred embodiment, in step S2, the electrophoresis solution is stirred at room temperature for 3 h to 6 h for aging.

[0026] In a preferred embodiment, step S3 includes placing the (Ce, Nd)-Fe-B magnet in an oxalic acid solution for pickling and activation treatment, placing it in deionized water for ultrasonic treatment after cleaning, then placing it in an anhydrous ethanol solution for ultrasonic treatment, and drying it for use.

[0027] In a preferred embodiment, step S3 further includes placing the (Ce, Nd)-Fe-B magnet in a 0.2 mol / L-0.8 mol / L oxalic acid solution for rust removal for 1 min-4 min, and after cleaning, placing it in deionized water for ultrasonic treatment for 10s-30s, and then placing it in an anhydrous ethanol solution for ultrasonic treatment for 1 min-5 min.

[0028] In a preferred embodiment, step S4 includes placing the acid-washed (Ce, Nd)-Fe-B magnet in an electrophoresis tank as a cathode to perform electrophoresis to prepare an epoxy-modified silicone resin composite coating, and then washing away the residual electrophoresis liquid on the surface with deionized water.

[0029] In a preferred embodiment, step S4 further includes using the pickled (Ce, Nd)-Fe-B magnet as a cathode for electrophoresis, with an operating voltage of 60V-110V, an operating environment temperature of 25°C-32°C, and a power-on time of 10s-60s.

[0030] In a preferred embodiment, step S5 includes: placing the (Ce, Nd)-Fe-B magnet after electrophoresis under a fan for pre-drying for 5 minutes to 10 minutes, and then placing it in a tube furnace for heating and curing for 60 minutes to 120 minutes;

[0031] The heat curing includes, more specifically, heating at 5°C / min-10°C / min to 150°C-200°C and holding for 60min-120min.

[0032] Technical effects and advantages of the present invention:

[0033] 1. The method for preparing epoxy-modified silicone resin of the present invention is simple, the reaction environment is easy to achieve, the poor compatibility between epoxy resin and silicone resin is improved, and the entire reaction process is green and environmentally friendly.

[0034] 2. The present invention utilizes water-based epoxy emulsion to react with methylphenyl silicone resin, and the obtained mixed resin can be prepared into electrophoretic liquid with electrophoretic slurry and water, and a coating is prepared on the surface of cerium neodymium iron boron magnet by cathode electrophoretic deposition method.

[0035] 3. The method for preparing epoxy-modified silicone resin composite coating of the present invention is flexible and simple, has high raw material utilization rate, and is easy to realize mechanized production, which is of great significance to industrial production.

[0036] 4. The epoxy-modified silicone resin coating prepared by the present invention has good corrosion resistance and prolongs the service life of the cerium-neodymium-iron-boron magnet under harsh conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 FTIR spectrum of the epoxy-modified silicone resin composite coating of the present invention;

[0038] Figure 2 This is a cross-sectional SEM image of the epoxy-modified organosilicon resin composite coating obtained in Example 2 of the present invention;

[0039] Figure 3 EIS curves of (Ce, Nd)-Fe-B coated with epoxy-modified silicone resin prepared with different resin ratios (epoxy resin: silicone resin = 1:1, 2:1, 3:1, 5:1) in the present invention, immersed in 3.5% NaCl solution for 30 days. DETAILED DESCRIPTION

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0041] Reference Figure 1 、 Figure 2 and Figure 3 , a method for preparing an epoxy-modified silicone resin composite coating on the surface of a (Ce, Nd)-Fe-B magnet,

[0042] Example 1:

[0043] Step S1: Activate bisphenol A epoxy resin (EP) at 90°C for 30 minutes. Mix the activated epoxy resin (EP) and methylphenyl silicone resin in a ratio of 1:1 (15 g:15 g), add phosphoric acid (0.06 g), and stir on a magnetic stirrer at 30°C for 40 minutes to obtain an epoxy-modified silicone resin.

[0044] Step S2: prepare an electrophoresis solution in a ratio of color paste: composite resin: deionized water = 1:6:10.5, and stir and mature it at room temperature for 5 hours; it is particularly important to note that the color paste is an ordinary dyeing color paste, and the composite resin is the epoxy-modified silicone resin in step S1.

[0045] Step S3: The (Ce, Nd)-Fe-B magnet sample was acid-washed with a 0.5 mol / L oxalic acid solution for 2.5 min, ultrasonically treated in deionized water for 20 s, and then ultrasonically treated in anhydrous ethanol solution for 1 min, and dried for later use;

[0046] Step S4: Place the acid-washed (Ce, Nd)-Fe-B magnet in an electrophoresis tank as the cathode for electrophoresis at 32° C., 100 V, and 10 seconds. Deionized water is then used to wash away any residual electrophoresis solution on the surface.

[0047] Step S5: The (Ce, Nd)-Fe-B magnet after electrophoresis was pre-dried under a fan for 10 minutes, and then placed in a tube furnace and heated to 180° C. for 30 minutes at a heating rate of 5° C. / min.

[0048] Summary: The epoxy-modified silicone resin composite resin coating obtained was dark black with uniform color and dense film layer. In the static full immersion test (NaCl solution concentration was 3.5%), the erythema time reached 768h.

[0049] Example 2:

[0050] Step S1: Activate bisphenol A epoxy resin (EP) at 90°C for 30 minutes. Mix the activated epoxy resin (EP) and methylphenyl silicone resin in a ratio of 2:1 (20 g:10 g), add phosphoric acid (0.06 g), and stir on a magnetic stirrer at 30°C for 40 minutes to obtain an epoxy-modified silicone resin.

[0051] Step S2: prepare an electrophoresis solution in a ratio of color paste: composite resin: deionized water = 1:6:10.5, and stir and mature it at room temperature for 5 hours; it is particularly important to note that the color paste is an ordinary dyeing color paste, and the composite resin is the epoxy-modified silicone resin in step S1.

[0052] Step S3: The (Ce, Nd)-Fe-B sample was acid-washed with a 0.5 mol / L oxalic acid solution for 2.5 min, ultrasonically treated in deionized water for 20 s, and then ultrasonically treated in anhydrous ethanol solution for 1 min, and dried for later use;

[0053] Step S4: Place the acid-washed (Ce, Nd)-Fe-B magnet in an electrophoresis tank as the cathode for electrophoresis at 32° C., 100 V, and 10 seconds. Deionized water is then used to wash away any residual electrophoresis solution on the surface.

[0054] Step S5: The (Ce, Nd)-Fe-B magnet after electrophoresis is placed under a fan for pre-drying for 10 minutes, and then placed in a tube furnace and heated to 180° C. for 30 minutes at a heating rate of 5° C. / min.

[0055] Summary: The obtained epoxy-modified silicone resin composite resin coating is dark black with uniform color and dense film layer. In the static full immersion test (NaCl solution concentration is 3.5%), the erythema time reaches 960 hours.

[0056] Example 3:

[0057] Step S1: Activate bisphenol A epoxy resin (EP) at 90°C for 30 minutes. Mix the activated epoxy resin (EP) and methylphenyl silicone resin in a ratio of 3:1 (22.5 g:7.5 g), add phosphoric acid (0.06 g), and stir on a magnetic stirrer at 30°C for 40 minutes to obtain an epoxy-modified silicone resin.

[0058] Step S2: prepare an electrophoresis solution in a ratio of color paste: composite resin: deionized water = 1:6:10.5, and stir and mature it at room temperature for 5 hours; it is particularly important to note that the color paste is an ordinary dyeing color paste, and the composite resin is the epoxy-modified silicone resin in step S1.

[0059] Step S3: The (Ce, Nd)-Fe-B sample was acid-washed with a 0.5 mol / L oxalic acid solution for 2.5 min, ultrasonically treated in deionized water for 20 s, and then ultrasonically treated in anhydrous ethanol solution for 1 min, and dried for later use;

[0060] Step S4: Place the acid-washed (Ce, Nd)-Fe-B magnet in an electrophoresis tank as the cathode for electrophoresis at 32° C., 100 V, and 10 seconds. Deionized water is then used to wash away any residual electrophoresis solution on the surface.

[0061] Step S5: The (Ce, Nd)-Fe-B magnet after electrophoresis is placed under a fan for pre-drying for 10 minutes, and then placed in a tube furnace and heated to 180° C. for 30 minutes at a heating rate of 5° C. / min.

[0062] Summary: The epoxy-modified silicone resin composite resin coating obtained was dark black with uniform color and dense film layer. In the static full immersion test (NaCl solution concentration was 3.5%), the erythema time reached 840 h.

[0063] Example 4:

[0064] Step S1: Activate bisphenol A epoxy resin (EP) at 90°C for 30 minutes. Mix the activated epoxy resin (EP) and methylphenyl silicone resin in a ratio of 5:1 (25 g:5 g), add phosphoric acid (0.06 g), and stir on a magnetic stirrer at 30°C for 40 minutes to obtain an epoxy-modified silicone resin.

[0065] Step S2: prepare an electrophoresis solution in a ratio of color paste: composite resin: deionized water = 1:6:10.5, and stir and mature it at room temperature for 5 hours; it is particularly important to note that the color paste is an ordinary dyeing color paste, and the composite resin is the epoxy-modified silicone resin in step S1.

[0066] Step S3: The (Ce, Nd)-Fe-B sample was acid-washed with a 0.5 mol / L oxalic acid solution for 2.5 min, ultrasonically treated in deionized water for 20 s, and then ultrasonically treated in anhydrous ethanol solution for 1 min, and dried for later use;

[0067] Step S4: Place the acid-washed (Ce, Nd)-Fe-B magnet in an electrophoresis tank as the cathode for electrophoresis at 32° C., 100 V, and 10 seconds. Deionized water is then used to wash away any residual electrophoresis solution on the surface.

[0068] Step S5: The (Ce, Nd)-Fe-B magnet after electrophoresis is placed under a fan for pre-drying for 10 minutes, and then placed in a tube furnace and heated to 180° C. for 30 minutes at a heating rate of 5° C. / min.

[0069] Summary: The epoxy-modified silicone resin composite resin coating obtained was dark black with uniform color and dense film layer. In the static full immersion test (NaCl solution concentration was 3.5%), the erythema time reached 720h.

[0070] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing an epoxy-modified silicone resin composite coating on the surface of a (Ce, Nd)-Fe-B magnet, characterized in that: The invention comprises the following preparation methods: Step S1: Preparation of epoxy-modified silicone resin; More specifically: The bisphenol A epoxy resin is treated to obtain an epoxy-modified silicone resin; Step S1 comprises activating bisphenol A epoxy resin at high temperature for 10-30 minutes, wherein the activation temperature of the bisphenol A epoxy resin is 70° C.-100° C. and the pH is adjusted to 7.5-9 using a dilute HCl solution; Step S1 further includes mixing the activated bisphenol A epoxy resin and methylphenyl silicone resin, adding phosphoric acid, and stirring for 20 minutes to 40 minutes to obtain an epoxy-modified silicone resin; Step S2: preparing electrophoresis fluid; More specifically: The color paste, epoxy modified silicone resin and deionized water are mixed to prepare an electrophoresis solution; Step S3: electrophoresis pre-treatment; More specifically: The (Ce, Nd)-Fe-B magnet is cleaned and dried; Step S4: electrophoresis treatment; More specifically: The (Ce, Nd)-Fe-B magnet is placed in the electrophoresis solution for treatment; Step S5: coating curing; More specifically: The (Ce, Nd)-Fe-B magnet after electrophoresis is heated and solidified.

2. The method for preparing an epoxy-modified silicone resin composite coating on the surface of a (Ce, Nd)-Fe-B magnet according to claim 1, characterized in that: In step S1, the activated bisphenol A epoxy resin and the silicone resin are mixed in a mass ratio of 1:1-6:1, and the phosphoric acid is 0.04g-0.1g.

3. The method for preparing an epoxy-modified silicone resin composite coating on the surface of a (Ce, Nd)-Fe-B magnet according to claim 1, characterized in that: In step S2, the electrophoresis solution is stirred at room temperature for 3 h to 6 h to mature.

4. The method for preparing an epoxy-modified silicone resin composite coating on the surface of a (Ce, Nd)-Fe-B magnet according to claim 1, characterized in that: Step S3 includes placing the (Ce, Nd)-Fe-B magnet in an oxalic acid solution for pickling and activation treatment, placing it in deionized water for ultrasonic treatment after cleaning, then placing it in an anhydrous ethanol solution for ultrasonic treatment, and drying it for later use.

5. The method for preparing an epoxy-modified silicone resin composite coating on the surface of a (Ce, Nd)-Fe-B magnet according to claim 4, characterized in that: Step S3 also includes placing the (Ce, Nd)-Fe-B magnet in a 0.2-0.8 mol / L oxalic acid solution for pickling and activation treatment for 1 min-4 min, placing it in deionized water for ultrasonic treatment for 10 s-30 s after cleaning, and then placing it in an anhydrous ethanol solution for ultrasonic treatment for 1 min-5 min.

6. The method for preparing an epoxy-modified silicone resin composite coating on the surface of a (Ce, Nd)-Fe-B magnet according to claim 1, characterized in that: Step S4 includes placing the acid-washed (Ce, Nd)-Fe-B magnet in an electrophoresis tank as a cathode to perform electrophoresis to prepare an epoxy-modified organic silicone resin composite coating, and then washing away residual electrophoresis liquid on the surface with deionized water.

7. The method for preparing an epoxy-modified silicone resin composite coating on the surface of a (Ce, Nd)-Fe-B magnet according to claim 6, characterized in that: Step S4 also includes using the pickled (Ce, Nd)-Fe-B magnet as a cathode for electrophoresis, with an operating voltage of 60V-110V, an operating environment temperature of 25°C-32°C, and a power-on time of 10s-60s.

8. The method for preparing an epoxy-modified silicone resin composite coating on the surface of a (Ce, Nd)-Fe-B magnet according to claim 1, characterized in that: Step S5 includes: placing the (Ce, Nd)-Fe-B magnet after electrophoresis under a fan for pre-drying for 5 minutes to 10 minutes, and then placing it in a tube furnace for heating and curing for 60 minutes to 120 minutes; The heat curing includes, more specifically, heating at 5°C / min-10°C / min to 150°C-200°C and holding for 60min-120min.

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