The development of insulated powder coating of aluminum round winding wire.

Abstract
In this paper, bisphenol A epoxy resin, phenolic epoxy resin and phenolic hydroxyphenol solidification agent as the main body of the film, studied the selection of epoxy resin and curing agent and the effect of ratio on the coating performance of powder coating, including flexibility and thermal properties, etc., through formula optimization, obtained an insulated powder coating suitable for paint-wrapped aluminum winding line.
Foreword
Paint-wrapped aluminum winding line is widely used in electric motors, generators, transformers and other fields, surface coating is currently mainly polyimide as the representative of solvent-based insulation coating, thermoso-solid powder coating with polyamide and other solvent-based coatings in terms of thermal performance and flexibility, but with Environmental protection requirements are getting higher and higher, paint-wrapped aluminum winding line manufacturers on the insulation powder coating demand is more and more urgent, this study produced insulation powder coating, can meet the national standard GB / T 23312 part of the standard requirements, softening the knock-through temperature can reach more than 210 degrees C, can achieve a solvent-based insulation coating partial replacement.
1 Experimental part
1.1 Raw materials
BPA epoxy resin (504), phenolic epoxy resin: industrial grade, Changchun Chemical (Jiangsu) Co., Ltd.;
phenol hydroxyphenol resin curing agent, industrial grade, Daqing Lulangrun Technology Co., Ltd.;
Powder coating general additives (leveling agents, moisturizers, sabbaths, etc.), industrial grade, Shanghai So is Chemical Co., Ltd.;
Organic pigments: industrial grade, Xiannico Chemical (Shanghai) Co., Ltd.;
Silicon micro-powder: industrial grade, Changxing Huayuan Powder Materials Co., Ltd.;
dimeth methamide: industrial grade, Langfang Hongtai Chemical Co., Ltd. .
1.2 main equipment
twin screw extruder, high-speed mixer, lmnable shredder, 200-eye manual screen, electrostation gun and experimental spray system, high temperature oven, membrane thickness instrument, automatic voltage tester, softening knock-through tester, elongation tester and so on.
1.3 Experimental process
1.3.1 Experimental formula
the ingredients required for the formula are accurately weighed as required in Table 1.
1.3.2 Raw material premixing
said to have taken the raw material placed in a high-speed mixer (Yantai Far Force Machinery Co., Ltd., FHJ-01N), stirring at 1200r/min speed mixing mix 180S, to obtain the components evenly dispersed premix.
1.3.3 Premix Extrusion Pressure
The extruder (Yantai Far Force Machinery Co., Ltd., SFJ-29A) parameters are set for temperature, feeding and extrusion speed as required in Table 2;
1.3.4 Sheet Smashing and Screening
places the collected sheet in a 10-piece shredder (Ryan City Seytt Electrical and Mechanical Co., Ltd., ST-512) and turns on the all-in-one shredder to crush the sheet Powdering, then pouring the powder into 200 manual screens for powder screening, to obtain a powder coating that meets the particle size requirements, the particle size range is generally in D50 (35 to 45) sm.
1.3.5 Pre-treatment of aluminum round wire and spraying and curing of powder coatings
the substrate is applied to eligible aluminum round wire (diameter 2.0mm, as shown in Figure 1), industrial pure alcohol is extracted from gauze, the aluminum round wire is wiped clean and dried in a clean ventilation place for use; Medium, with a good powder coating sprayed on the surface of the aluminum round line, the sprayed aluminum round wire in a 200 degrees C oven baking curing, baking time of 15 to 20min, after curing, take out the finished round line, natural cooling, and with a membrane thickness meter (Qnix44500) measurement film thickness should be between (100 to 120 m).
2 results and discussion
2.1 paint package aluminum round winding line powder coating main performance test results
in accordance with the relevant regulations and test methods of the national standard GB/T 23312 paint package aluminum winding line powder coating performance test, test results as shown in Table 3 and Figure 2, Figure 3, Figure 4, Figure 5.
2.2 Effect of raw material selection on product performance
Epoxy resins currently suitable for powder coatings are mainly bisphenol A and phthalates type 2, bisphenol A epoxy resin comprehensive performance is excellent, with curing agents Crosslinking reaction has good flexibility, but the crosslink density is limited, so heat resistance is not high, and the adjacent formaldehyde epoxy resin reacts with curing agent to form a higher crosslink density, thus improving the heat resistance of the coating, but the flexibility is poor. We use bisphenol A epoxy resin and adjacent formaldehyde epoxy resin compound, to obtain a balance of flexibility and heat resistance.
test, bisphenol A-type epoxy resin with epoxy equivalent of 780 to 850, phthalates epoxy resin with epoxy equivalent of 200 to 300, and phenolic hydroxyphenol resin was selected for curing agent, which produces modified phenolic resin combining flexible chain and rigid chain with excellent temperature resistance and flexibility.
test results of Tables 1 and 3 show that as the amount of acetaldehyde epoxy resins in the formulation gradually increases, the softening and perforation temperature of the coating gradually increases, but the flexibility decreases gradually. Powder coating products with a balance of flexibility and temperature resistance are obtained in formula F softening the knock-through temperature to reach 210 degrees C.
3 Conclusion
Epoxy resin / phenolic hydroxyphenolic resin curing system of the paint-wrapped aluminum round winding line powder coating physical mechanical properties, electrical insulation properties, etc. have reached the national standard GB / T 23312 related requirements, softening the knock-through temperature can reach about 210 degrees C, products can be replaced in a certain range of polyimide as the representative of solvent-based insulation paint.
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