1.What are the core requirements for high temperature discoloration resistance?
Color difference
Industry general standard: After high temperature testing, the color difference ΔE between the coating and the original state must be ≤3. The smaller the ΔE value, the slighter the discoloration, which is almost imperceptible to the naked eye.
Test method: Place the color coated coil sample in a specific high temperature environment for a certain period of time, and use a colorimeter to detect the color difference before and after cooling.
Gloss retention rate
After high temperature treatment, the gloss retention rate of the coating is required to be ≥80%. Excessive gloss reduction will cause the surface to be dull and affect the appearance texture.
Appearance defects
Cracking, blistering, powdering, peeling and other accompanying phenomena of the coating are not allowed, and only slight discoloration is considered qualified.
2.What are the temperature range requirements for common industrial and construction scenarios?
Applicable temperature: -40℃~120℃.
Typical scenarios: building exterior walls, roofs, home appliance housings, interior decoration, etc.
Requirements: No obvious discoloration when used for a long time below 120℃; when exposed to high temperature of 150℃ for a short time, the color difference ΔE≤3.
3.What are the temperature range requirements for medium and high temperature industrial scenarios?
Applicable temperature: 120℃~200℃.
Typical scenarios: oven shell, parts near automobile exhaust pipe, high-temperature pipe outer sheath, drying equipment shell, etc.
Requirements: After continuous use at 180℃ for 72 hours, the color difference ΔE≤3, and there is no coating degradation; it can withstand a peak temperature of 200℃ in a short term.
4.What is the weather resistance and stability of color coated coils?
Thermal cycle stability
In a high and low temperature alternating environment, it is necessary not only to withstand a single high temperature, but also to maintain color change stability under repeated hot and cold shocks to avoid cracking or accelerated color change of the coating due to thermal expansion and contraction.
Synergistic effect of UV resistance and high temperature
Outdoor high temperature scenes (such as roofs and exterior walls) need to withstand both sunlight ultraviolet rays and high temperatures. The coating is required to maintain low color difference (ΔE≤3) under the combined effect of "high temperature + ultraviolet rays" to avoid aggravated color change due to photooxidation reaction.
Long-term heat resistance
For products that are in medium and high temperature environments for a long time (such as industrial oven shells), it is required to be used continuously for more than 1 year at the rated temperature, and the cumulative color difference ΔE is still ≤5 (avoid frequent replacement).
5.What are the core requirements for color-coated coils to resist high-temperature discoloration?
The core requirement of color-coated coils' resistance to high-temperature discoloration is to have small color difference, good gloss retention, and no appearance defects at a specific temperature and time. The specific indicators need to be determined in combination with the temperature range of the application scenario (from room temperature to above 300°C) and the weathering cycle. Color-coated coils that meet these requirements need to rely on high-performance coating materials (such as silicon-modified polyester and fluorocarbon resin) and advanced coating processes to ensure appearance stability and service life in high-temperature environments.