1.What are the testing principles and characteristics of ultraviolet (UV) aging tests?
Main Equipment: QUV Accelerated Aging Chamber (most commonly used) or Q-SUN Xenon Chamber.
Test Principle:
QUV: Uses ultraviolet fluorescent lamps to simulate the ultraviolet band of sunlight, combined with condensation or spray functions to simulate dew and rain. Primarily assesses the coating's chalking, fading, gloss loss, and cracking properties.
Q-SUN: Uses xenon arc lamps, simulating a more complete solar spectrum (including ultraviolet, visible, and infrared light), more closely resembling real sunlight.
Test Standards:
ASTM G154: Standard Operating Procedure for Fluorescent Ultraviolet Lamp Exposure Testing of Nonmetallic Materials.
ISO 16474-3: Coatings and varnishes – Laboratory light source exposure methods – Part 3: Fluorescent ultraviolet lamps.
2.What are the principles and characteristics of salt spray corrosion testing?
Main Equipment: Salt Spray Test Chamber.
Test Principle: Creates a constant temperature and humidity environment with continuous spraying of neutral or acidic salt spray. This primarily assesses the coating's corrosion resistance, adhesion, and scratch propagation (scratch test) capability. This is particularly important for evaluating edge protection performance.
Test Standards:
ASTM B117: Standard Operating Procedure for Salt Spray Testing.
ISO 9227: Artificial Atmosphere Corrosion Testing - Salt Spray Testing.
Common Evaluation Indicators: After a certain testing time (e.g., 500h, 1000h), inspect the surface for blistering and rust, and evaluate the width of the corrosion spread (unit: mm) on one side of the scratch.
3.What is the principle behind damp heat resistance testing?
Test Principle: The test assesses coating blistering and adhesion degradation under high temperature and humidity conditions (e.g., temperature 40℃±2℃, relative humidity above 95%).
Test Standard: ASTM D2247 or ISO 6270 (condensation immersion test).
4.What is the principle behind outdoor natural exposure testing?
Test Principle: Samples are subjected to long-term exposure in realistic, representative outdoor environments (such as industrial areas, coastlines, rural areas, deserts, etc.). This is the most realistic and reliable method, but the period is very long (usually measured in years).
Main Locations: World-renowned exposure sites include Florida (high temperature, strong UV radiation, high humidity) and Arizona (dry heat, strong UV radiation) in the United States, and Guangzhou, Dunhuang, and Mohe in China (representing humid heat, dry heat and dust, and frigid climates, respectively).
Test Standards:
ASTM G7: Standard procedure for testing the natural aging of nonmetallic materials outdoors.
ISO 2810: Paints and varnishes – Guidelines for natural aging exposure.
Evaluation Indicators: Samples are taken periodically (e.g., every 6 months, 1 year, 2 years, 5 years) to evaluate overall performance, including color difference, gloss, chalking, mildew, and corrosion.
5.What are the performance evaluation criteria?
Grading and Evaluation: Different grades of color-coated coils correspond to different testing requirements. For example:
Ordinary Polyester (PE) Coating: Typically requires QUV testing ≥ 600 hours and neutral salt spray (NSS) ≥ 500 hours without red rust.
High Weather-Resistant Polyester (HDP)/Silicone-Modified Polyester (SMP) Coating: Typically requires QUV ≥ 1000 hours and salt spray ≥ 1000 hours.
Polyvinylidene Fluoride (PVDF) Coating: Typically requires QUV ≥ 2000 hours and salt spray ≥ 1000 hours, representing the highest grade.
Warranty Basis: Well-known color-coated coil manufacturers (such as Bluestar, Yieh Phui, Baosteel, etc.) offer 10-year, 15-year, 20-year, or even longer quality guarantees. The core basis for these guarantees comes from the correlation and comparison of their rigorous laboratory accelerated aging test data and long-term outdoor exposure databases.