1.What are the requirements of the two-coat and two-bake process for workshop temperature and humidity?
Temperature: 20-30℃ (optimal 23±2℃) is usually required. Too low temperature (<15℃) will lead to poor leveling and poor curing of the coating; too high temperature (>35℃) will accelerate solvent evaporation, causing defects such as orange peel and pinholes.
Relative humidity: Strictly controlled at 40%-70% (optimal 50-60%). Too high humidity (>80%) will lead to: Condensation on the surface of the substrate, affecting the adhesion of the coating
Imbalance of solvent evaporation rate, causing the paint film to turn white and lose gloss
Ineffectiveness of curing agent (such as isocyanate) reacting with water
Measures: The coating workshop needs to be equipped with a constant temperature and humidity air conditioning system for real-time monitoring and adjustment.
2.What are the requirements for air cleanliness in the two-coat and two-bake process?
Dust-proof level: The coating line must reach 100,000 (ISO Class 8) cleanliness.
Dust particles (＞5μm) will embed into the wet film to form convex spots, causing coating shrinkage and particle defects. Measures: Closed workshop design + positive pressure air supply system
High efficiency filtration (HEPA) air intake device
Dust-proof treatment (epoxy floor)
Personnel wear dust-proof clothing/shoe covers
3.What are the requirements for lighting conditions for the two-coat and two-bake process?
Illumination of inspection area: ≥ 500 lux (using high color rendering LED light source), which is convenient for visual inspection of coating defects.
Light protection requirements: Some primers (such as epoxy) need to be stored away from light to prevent photosensitivity reactions.
4.What are the requirements of the two-coating and two-baking process for the external environment?
Waste gas heat recovery: The exhaust temperature of the oven can reach 150-250℃, and a heat exchanger is required to recover waste heat (preheat fresh air or production water) to reduce energy consumption.
Hazardous waste treatment Hazardous waste: Waste solvents, paint residues, waste activated carbon, etc. are HW12/13 hazardous wastes. Requirements: Entrust qualified units to handle, implement the transfer joint form system, and prohibit illegal emissions.
Noise control: The noise of equipment such as fans and pumps must meet GB 12348-2008: ≤65 dB(A) at the factory boundary during the day.
Measures: Sound insulation cover, muffler, vibration reduction foundation.
5. What suggestions are there for dealing with extreme climates?
High humidity areas (such as coastal areas): add dehumidifiers + pre-drying sections to ensure that the substrate temperature before coating is 3°C above the dew point.
High dust areas (such as industrial areas) ◦ Upgrade to ISO Class 7 cleanliness and add air showers.
Low temperature areas (<5°C): Store the paint in a constant temperature room (15-25°C) and add steam heating to the pipeline.