What are the precautions for spraying ECTFE on lithium battery equipment

Source：www.cicaero.cn Release date： 2025年02月05日

Information summary：When spraying ECTFE (ethylene trifluorochloroethylene copolymer) on lithium battery equipment, there are many key points to pay attention to, including surface treatment, spraying environment, material selection, etc. The following is a specific introduction: 1. Surface treatment Cleaning: The surface of the parts to be sprayed on lithium battery equipment must be cleaned to remove impuriti

When spraying ECTFE (ethylene trifluorochloroethylene copolymer) on lithium battery equipment, there are many key points to pay attention to, including surface treatment, spraying environment, material selection, etc. The following is a specific introduction:
1. Surface treatment
Cleaning: The surface of the parts to be sprayed on lithium battery equipment must be cleaned to remove impurities such as oil stains, dust, rust, and release agents. Solvent cleaning, sandblasting, and other methods can be used. If there is oil stains on the surface, it will cause a decrease in the adhesion of the ECTFE coating and result in peeling.
Coarsening: To enhance coating adhesion, it is usually necessary to roughen the surface, such as sandblasting or chemical corrosion. The degree of roughening should be moderate, as excessive roughening can result in uneven surface roughness, affecting the appearance and performance of the coating; The effect of improving adhesion through detailed rules is not significant.
2. Spray environment
Temperature: The spraying environment temperature should be controlled between 15 ℃ and 35 ℃. If the temperature is too low, the leveling of ECTFE coating will be poor, resulting in defects such as orange peel and sagging; If the temperature is too high and the coating dries too quickly, it may cause the spray gun to clog and increase the internal stress of the coating, making it easy to crack.
Humidity: The environmental humidity should be maintained between 40% and 70%. Excessive humidity can lead to the formation of a water film on the surface of the coating, resulting in blistering, whitening, and reduced adhesion; Low humidity can generate static electricity, causing uneven dispersion of coating particles during the spraying process.
Ventilation: The spraying area should have a good ventilation system to timely discharge volatile solvents and exhaust gases, which can reduce the concentration of flammable gases and prevent safety accidents such as explosions; On the other hand, it can timely release the volatile gases during the drying process of the coating, avoiding affecting the quality of the coating.
3. Material selection
ECTFE coating: The appropriate model of ECTFE coating should be selected based on the usage environment and performance requirements of lithium battery equipment. For components that come into contact with electrolytes, coatings with good resistance to electrolyte corrosion should be selected; For areas with high wear resistance requirements, ECTFE coatings containing wear-resistant fillers should be selected.
Diluent: Use the diluent that matches the ECTFE coating and dilute it strictly according to the specified ratio. Excessive use of diluent can reduce the solid content of the coating, affecting the thickness and performance of the coating; Insufficient dosage, high viscosity of coating, difficulty in spraying, affecting atomization effect.
4. Spraying operation
Spray gun debugging: Before spraying, it is necessary to carefully debug the spray gun, including adjusting parameters such as pressure, flow rate, and nozzle diameter. Excessive pressure can cause excessive atomization of the coating, resulting in thinning and unevenness of the coating; Insufficient pressure can lead to poor atomization of the coating, resulting in accumulation and sagging.
Spray thickness: The principle of multiple thin coatings should be followed, and the thickness of each spray should be controlled within an appropriate range. Generally, the dry film thickness is around 50-100 microns per coat. If the coating is sprayed too thick at once, bubbles and pinholes are easily generated inside the coating, and the drying and curing time is long, which can lead to problems such as cracking and peeling.
Spray distance and angle: The distance between the spray gun and the surface of the object to be coated is generally maintained at 150-300 millimeters, and the spray angle is around 90 degrees. Being too close can lead to paint accumulation; Distance too far, paint scattering, low utilization rate, and poor coating uniformity.
5. Curing treatment
Temperature control: After spraying the ECTFE coating, it needs to undergo curing treatment. The curing temperature is usually between 230 ℃ -280 ℃, and the specific temperature is determined according to the coating formula and equipment requirements. The curing temperature is too low, the coating cannot fully crosslink and cure, and the performance does not meet the requirements; Excessive temperature can cause coating aging and discoloration, affecting its service life.
Curing time: The curing time is generally 1-3 hours, and the specific time depends on factors such as coating thickness, curing temperature, and equipment heating efficiency. The curing time is too short, and the coating curing is incomplete; Excessive time not only increases production costs, but may also have adverse effects on coating performance.
6. Quality inspection
Appearance inspection: After the coating is cured, the first step is to conduct an appearance inspection to observe whether the coating surface is flat, smooth, and whether there are defects such as bubbles, pinholes, sagging, orange peel, etc. If any appearance defects are found, the cause should be analyzed in a timely manner and corresponding measures should be taken for repair.
Performance testing: Testing the performance of coatings, such as adhesion, hardness, corrosion resistance, etc. Adhesion can be tested using the grid method, hardness can be measured using a hardness tester, and corrosion resistance can be tested through salt spray tests. Coatings that fail performance testing need to be re sprayed or remedial measures taken.

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