Preparation method of epoxy modified acrylic resin light-cured composite coating on surface of NdFeB magnet

Abstract

The invention relates to the technical field of preparation methods of composite coatings, in particular to a preparation method of an epoxy modified acrylic resin light-cured composite coating on the surface of an NdFeB magnet, and the preparation method comprises the following steps: S1, preparing mixed resin; mixing bisphenol A epoxy resin with acrylic resin to obtain mixed resin; the method for preparing the epoxy modified acrylic light-cured composite coating is simple, grafting modification of acrylic resin is not needed, the raw material utilization rate is high, the preparation time is short, and mechanical production is easy to achieve; the waterborne epoxy emulsion and the waterborne acrylic resin are mixed, the obtained mixed resin and water can be prepared into electrophoretic liquid, and the coating is prepared on the surface of the neodymium-iron-boron magnet through a cathode electrophoretic deposition method; the prepared epoxy modified acrylic resin light-cured composite coating has good corrosion resistance, and the service life of the neodymium-iron-boron magnet under harsh conditions is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of composite coating preparation methods, and more specifically to a method for preparing an epoxy-modified acrylic resin photocuring composite coating on the surface of a NdFeB magnet. Background Art

[0002] As an important rare earth application material, NdFeB rare earth permanent magnet material is closely related to people's lives. It is a magnetic material with extremely high magnetic energy product and coercivity, and is widely used in various types of motors, instruments and meters with excellent performance. However, the multiphase structure in NdFeB and the differences in chemical properties between the phases make NdFeB rare earth permanent magnet materials show inherent insufficient corrosion resistance, which limits its development. In recent years, on the one hand, with the increasing application scope of NdFeB rare earth permanent magnet materials and the continuous improvement of user requirements, in the past, more attention was paid to its magnetic properties, but now requirements are also put forward for surface corrosion resistance, beautiful appearance, and even antibacterial properties; on the other hand, the relatively backward surface protection technology and equipment of domestic rare earth permanent magnet materials have become a bottleneck restricting China's development from a rare earth permanent magnet power to a strong country. These problems have forced the innovation and progress of the corrosion protection technology of NdFeB rare earth permanent magnet materials. To make up for the shortcoming of corrosion protection that restricts the development of NdFeB rare earth permanent magnet materials, it is necessary to use new corrosion protection technologies, new processes and new methods to obtain NdFeB materials with better comprehensive performance to meet the requirements of practical applications.

[0003] Surface protection is currently the most widely used corrosion protection method, among which organic coating is the most convenient and economical surface treatment technology. Traditional organic coatings have long curing time, poor moisture and heat resistance, weak aging resistance and other disadvantages. At the same time, the generation of organic protective film will produce environmental problems such as waste liquid and waste residue, which further increases the production cost. Therefore, the future research direction should be to develop diversified organic coatings, improve the anti-corrosion and mechanical properties of the coatings, and try to use less polluting materials. Photocuring is a "green" new technology. At this stage, its development speed is getting faster and faster, and its application range is constantly expanding. Compared with thermal curing, it has the advantages of high efficiency and excellent performance. Compared with thermal curing, the curing time is greatly reduced. Photocuring coatings will inevitably gradually replace traditional thermal curing coatings and become the mainstream. However, the poor bonding strength of pure photocuring acrylic resin coatings to the substrate leads to its poor corrosion resistance.

[0004] Therefore, we proposed a method for preparing epoxy-modified acrylic resin photocuring composite coating on the surface of NdFeB magnet to solve the above problems. Summary of the invention

[0005] In order to overcome the above defects of the prior art, an embodiment of the present invention provides a method for preparing an epoxy-modified acrylic resin photocurable composite coating on the surface of a NdFeB magnet to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a method for preparing an epoxy-modified acrylic resin photocurable composite coating on the surface of a NdFeB magnet, comprising the following preparation method:

[0007] Step S1: preparation of mixed resin;

[0008] Mixing bisphenol A epoxy resin and acrylic resin to obtain a mixed resin;

[0009] Step S2: preparing electrophoresis fluid;

[0010] The mixed resin, photoinitiator and deionized water in step S1 are mixed to prepare an electrophoresis solution;

[0011] Step S3: electrophoresis pretreatment;

[0012] The NdFeB magnet is cleaned and dried;

[0013] Step S4: electrophoresis treatment;

[0014] The NdFeB magnet is placed in the electrophoresis solution in step S2 for treatment;

[0015] Step S5: coating curing;

[0016] The NdFeB magnet after electrophoresis is cured by ultraviolet light.

[0017] In a preferred embodiment, step S1 includes:

[0018] The bisphenol A epoxy resin and the acrylic resin are mixed, and the added amount of the bisphenol A epoxy resin is 10wt%-25wt%.

[0019] In a preferred embodiment, in step S2;

[0020] The mixed resin is mixed with 3wt%-5wt% of a photoinitiator and deionized water to prepare an electrophoresis solution;

[0021] Step S2 also includes:

[0022] The electrophoresis solution in step S2 is stirred at room temperature for 2 h-3 h.

[0023] In a preferred embodiment, step S3 includes:

[0024] The NdFeB magnet is placed in a nitric acid solution for pickling, and after cleaning, it is placed in deionized water for ultrasonic treatment, and then placed in an absolute ethanol solution for ultrasonic treatment, and then dried for use;

[0025] Step S3 also includes:

[0026] The NdFeB magnet was placed in a 3vt% nitric acid solution for pickling for 15s-30s. After cleaning, it was placed in deionized water for ultrasonic treatment for 30s-60s. The above operation was repeated once. Then, the magnet was placed in anhydrous ethanol solution for ultrasonic treatment for 1min and dried with a hair dryer.

[0027] In a preferred embodiment, step S4 comprises:

[0028] The acid-washed NdFeB magnet is placed in an electrophoresis tank for cathode electrophoresis to prepare an epoxy-modified acrylic resin photocurable composite coating, and then the residual electrophoresis liquid on the surface is washed away with deionized water;

[0029] Step S4 also includes:

[0030] The pickled NdFeB magnet is subjected to cathode electrophoresis, the working voltage is 60V-80V, the working environment temperature is 25℃-30℃, and the power-on time is 10s-20s.

[0031] In a preferred embodiment, step S5 includes:

[0032] The NdFeB magnet after electrophoresis is placed under a fan for pre-drying for 5-10 minutes, then placed in a 70° oven for flash evaporation for 10-15 minutes, and then placed under a UV curing lamp for irradiation;

[0033] Step S5 also includes:

[0034] The UV lamp irradiation time is 30s-60s, and the irradiation distance is 5cm.

[0035] Technical effects and advantages of the present invention:

[0036] The method for preparing the epoxy-modified acrylic light-curing composite coating is simple, does not require grafting modification of acrylic resin, has high raw material utilization rate, short preparation time, and is easy to realize mechanical production.

[0037] The invention uses water-based epoxy emulsion and water-based acrylic resin to mix, and the obtained mixed resin can be prepared into electrophoresis liquid with water, and a coating is prepared on the surface of a neodymium iron boron magnet by a cathode electrophoresis deposition method.

[0038] The epoxy-modified acrylic resin light-cured composite coating prepared by the invention has good corrosion resistance and prolongs the service life of the NdFeB magnet under harsh conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a cross-sectional SEM image of the epoxy-modified acrylic resin photocurable composite coating obtained in Example 2 of the present invention;

[0040] Figure 2 EIS curves of NdFeB of epoxy-modified acrylic resin photocurable composite coating prepared with different epoxy resin addition amounts in the present invention, immersed in 3.5% NaCl solution for 14 days. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0042] Reference Figure 1 and Figure 2 , a method for preparing an epoxy-modified acrylic resin photocurable composite coating on the surface of a NdFeB magnet;

[0043] A method for preparing an epoxy-modified acrylic resin photocuring composite coating on the surface of a NdFeB magnet.

[0044] Embodiment 1:

[0045] Step S1: Mix bisphenol A epoxy resin and acrylic resin (EA), wherein the addition amount of bisphenol A epoxy resin is 20 wt % of the acrylic resin (EA), to obtain a mixed resin.

[0046] Step S2: Add a photoinitiator to the mixed resin, the amount of the photoinitiator added is 3wt% of the acrylic resin, and prepare an electrophoresis solution in a ratio of acrylic resin to deionized water = 7:43.

[0047] Step S3: The NdFeB magnet is placed in a 3vt% nitric acid solution for pickling for 30 seconds. After cleaning, the magnet is placed in deionized water for ultrasonic treatment for 1 minute. The above operation is repeated once. The magnet is then placed in an anhydrous ethanol solution for ultrasonic treatment for 1 minute and blow-dried with a hair dryer.

[0048] Step S4: placing the acid-washed NdFeB magnet in an electrophoresis tank for cathode electrophoresis to prepare an epoxy-modified acrylic resin photocurable composite coating;

[0049] Electrophoresis parameters: 25°, 60V, 15s;

[0050] Then, the residual electrophoresis solution on the surface was washed away with deionized water.

[0051] Step S5: The NdFeB magnet after electrophoresis is placed under a fan for pre-drying for 10 minutes, and then placed in a 70° oven for flash evaporation for 10 minutes, and then placed under a UV curing lamp for 30 seconds at a distance of 5 cm.

[0052] Embodiment 2:

[0053] Step S1: Mix bisphenol A epoxy resin and acrylic resin (EA), wherein the addition amount of bisphenol A epoxy resin is 15 wt % of the acrylic resin (EA), to obtain a mixed resin.

[0054] Step S2: Add a photoinitiator to the mixed resin, the amount of the photoinitiator added is 3wt% of the acrylic resin, and prepare the electrophoresis liquid in a ratio of acrylic resin: deionized water = 7:43.

[0055] Step S3: The NdFeB magnet is placed in a 3vt% nitric acid solution for pickling for 30 seconds. After cleaning, the magnet is placed in deionized water for ultrasonic treatment for 1 minute. The above operation is repeated once. The magnet is then placed in an anhydrous ethanol solution for ultrasonic treatment for 1 minute and blow-dried with a hair dryer.

[0056] Step S4: placing the acid-washed NdFeB magnet in an electrophoresis tank for cathode electrophoresis to prepare an epoxy-modified acrylic resin photocurable composite coating;

[0057] Electrophoresis parameters: 25°, 60V, 15s;

[0058] Then, the residual electrophoresis solution on the surface was washed away with deionized water.

[0059] Step S5: The NdFeB magnet after electrophoresis is placed under a fan for pre-drying for 10 minutes, and then placed in a 70° oven for flash evaporation for 10 minutes, and then placed under a UV curing lamp for 30 seconds at a distance of 5 cm.

[0060] Embodiment 3:

[0061] Step S1: Mix bisphenol A epoxy resin and acrylic resin (EA), wherein the addition amount of bisphenol A epoxy resin is 10 wt % of the acrylic resin (EA), to obtain a mixed resin.

[0062] Step S2: Add a photoinitiator to the mixed resin, the amount of the photoinitiator added is 3wt% of the acrylic resin, and prepare an electrophoresis solution in a ratio of acrylic resin to deionized water = 7:43.

[0063] Step S3: The NdFeB magnet is placed in a 3vt% nitric acid solution for pickling for 30 seconds. After cleaning, the magnet is placed in deionized water for ultrasonic treatment for 1 minute. The above operation is repeated once. The magnet is then placed in an anhydrous ethanol solution for ultrasonic treatment for 1 minute and blow-dried with a hair dryer.

[0064] Step S4: placing the acid-washed NdFeB magnet in an electrophoresis tank for cathode electrophoresis to prepare an epoxy-modified acrylic resin photocurable composite coating;

[0065] Electrophoresis parameters: 25°, 60V, 15s;

[0066] Then, the residual electrophoresis solution on the surface was washed away with deionized water.

[0067] Step S5: The NdFeB magnet after electrophoresis is placed under a fan for pre-drying for 10 minutes, and then placed in a 70° oven for flash evaporation for 10 minutes, and then placed under a UV curing lamp for 30 seconds at a distance of 5 cm.

[0068] Embodiment 4:

[0069] Step S1: Mix bisphenol A epoxy resin and acrylic resin (EA), wherein the addition amount of bisphenol A epoxy resin is 25 wt % of the acrylic resin (EA), to obtain a mixed resin.

[0070] Step S2: Add a photoinitiator to the mixed resin, the amount of the photoinitiator added is 3wt% of the acrylic resin, and prepare an electrophoresis solution in a ratio of acrylic resin to deionized water = 7:43.

[0071] Step S3: The NdFeB magnet is placed in a 3vt% nitric acid solution for pickling for 30 seconds. After cleaning, the magnet is placed in deionized water for ultrasonic treatment for 1 minute. The above operation is repeated once. The magnet is then placed in an anhydrous ethanol solution for ultrasonic treatment for 1 minute and blow-dried with a hair dryer.

[0072] Step S4: placing the acid-washed NdFeB magnet in an electrophoresis tank for cathode electrophoresis to prepare an epoxy-modified acrylic resin photocurable composite coating;

[0073] Electrophoresis parameters: 25°, 60V, 15s;

[0074] Then, the residual electrophoresis solution on the surface was washed away with deionized water.

[0075] Step S5: The NdFeB magnet after electrophoresis is placed under a fan for pre-drying for 10 minutes, and then placed in a 70° oven for flash evaporation for 10 minutes, and then placed under a UV curing lamp for 30 seconds at a distance of 5 cm.

[0076] In summary, the following table can be obtained:

[0077]

[0078]

[0079] Secondly, the following conclusions can be drawn:

[0080] Example 1: The obtained epoxy-modified acrylic resin light-cured composite coating is dark transparent, uniform in color, and has a dense film layer;

[0081] After two weeks of full immersion corrosion test, |Z|0.01Hz is 5.782×10 6 Ω·cm 2 .

[0082] Example 2: The obtained epoxy-modified acrylic resin light-cured composite coating is dark transparent, uniform in color, and has a dense film layer;

[0083] After two weeks of full immersion corrosion test, |Z|0.01Hz is 1.175×10 6 Ω·cm 2 .

[0084] Embodiment three:

[0085] The obtained epoxy modified acrylic resin light-cured composite coating is deep transparent, uniform in color, and has a dense film layer;

[0086] After two weeks of full immersion corrosion test, |Z|0.01Hz is 5.166×10 5 Ω·cm 2 .

[0087] Embodiment 4:

[0088] The obtained epoxy modified acrylic resin light-cured composite coating is deep transparent, uniform in color, and has a dense film layer;

[0089] In the full immersion corrosion test, |Z|0.01Hz after two weeks is 2.242×10 5 Ω·cm 2 .

[0090] Finally, a few points should be explained: First, in the description of this application, it should be noted that, unless otherwise specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, which may refer to mechanical connection or electrical connection, or internal communication between two components, or direct connection. "upper", "lower", "left", "right", etc. are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may change;

[0091] Secondly: In the drawings of the embodiments disclosed in the present invention, only the structures related to the embodiments disclosed in the present invention are involved, and other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of the present invention can be combined with each other;

[0092] 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 protection scope of the present invention.

Claims

1. A method for preparing an epoxy-modified acrylic resin photocurable composite coating on the surface of a NdFeB magnet, characterized in that: The invention comprises the following preparation methods: Step S1: preparation of mixed resin; Mixing bisphenol A epoxy resin and acrylic resin to obtain a mixed resin; Step S2: preparing electrophoresis fluid; The mixed resin, photoinitiator and deionized water in step S1 are mixed to prepare an electrophoresis solution; Step S3: electrophoresis pretreatment; The NdFeB magnet is cleaned and dried; Step S4: electrophoresis treatment; The NdFeB magnet is placed in the electrophoresis solution in step S2 for treatment; Step S5: coating curing; The NdFeB magnet after electrophoresis is cured by ultraviolet light.

2. The method for preparing an epoxy-modified acrylic resin light-cured composite coating on the surface of a NdFeB magnet according to claim 1, characterized in that: Step S1 comprises: The bisphenol A epoxy resin and the acrylic resin are mixed, and the added amount of the bisphenol A epoxy resin is 10wt%-25wt%.

3. The method for preparing an epoxy-modified acrylic resin light-cured composite coating on the surface of a NdFeB magnet according to claim 1, characterized in that: In step S2; The mixed resin is mixed with 3wt%-5wt% of a photoinitiator and deionized water to prepare an electrophoresis solution.

4. The method for preparing an epoxy-modified acrylic resin light-cured composite coating on the surface of a NdFeB magnet according to claim 3, characterized in that: Step S2 also includes: The electrophoresis solution in step S2 is stirred at room temperature for 2 h-3 h.

5. The method for preparing an epoxy-modified acrylic resin light-cured composite coating on the surface of a NdFeB magnet according to claim 1, characterized in that: Step S3 comprises: The NdFeB magnet is placed in a nitric acid solution for pickling treatment, placed in deionized water for ultrasonic treatment after cleaning, and then placed in an anhydrous ethanol solution for ultrasonic treatment, and dried for use.

6. The method for preparing an epoxy-modified acrylic resin light-cured composite coating on the surface of a NdFeB magnet according to claim 5, characterized in that: Step S3 also includes: The NdFeB magnet was placed in a 3vt% nitric acid solution for pickling for 15s-30s. After cleaning, it was placed in deionized water for ultrasonic treatment for 30s-60s. The above operation was repeated once. Then, the magnet was placed in anhydrous ethanol solution for ultrasonic treatment for 1min and dried with a hair dryer.

7. The method for preparing an epoxy-modified acrylic resin light-cured composite coating on the surface of a NdFeB magnet according to claim 1, characterized in that: Step S4 comprises: The acid-washed NdFeB magnet was placed in an electrophoresis tank for cathode electrophoresis to prepare an epoxy-modified acrylic resin photocurable composite coating, and then the residual electrophoresis liquid on the surface was washed away with deionized water.

8. The method for preparing an epoxy-modified acrylic resin light-cured composite coating on the surface of a NdFeB magnet according to claim 7, characterized in that: Step S4 also includes: The pickled NdFeB magnet is subjected to cathode electrophoresis, the working voltage is 60V-80V, the working environment temperature is 25℃-30℃, and the power-on time is 10s-20s.

9. The method for preparing an epoxy-modified acrylic resin light-cured composite coating on the surface of a NdFeB magnet according to claim 1, characterized in that: Step S5 comprises: The NdFeB magnet after electrophoresis is placed under a fan for pre-drying for 5min-10min, then placed in a 70° oven for flash evaporation for 10min-15min, and then irradiated under a UV curing lamp.

10. The method for preparing the epoxy-modified acrylic resin light-cured composite coating on the surface of NdFeB magnet according to claim 9, characterized in that: Step S5 also includes: The UV lamp irradiation time is 30s-60s, and the irradiation distance is 5cm.

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