In the field of materials science, the aging resistance of artificial leather is a key indicator of its long-term reliability. The UV aging test chamber provides an efficient and controllable testing method for evaluating the aging resistance of artificial leather by simulating and accelerating aging factors such as light, heat, and humidity in the natural environment. This paper aims to elaborate on the principles, methods, evaluation indicators and related technical considerations of using UV aging test chambers to evaluate the aging resistance of artificial leather.
Rationale
The core of UV aging test is to use fluorescent UV lamps to simulate ultraviolet band radiation in sunlight. In the solar spectrum, ultraviolet light (especially in the UV-A and UV-B bands) is the main factor causing photochemical degradation of polymer materials such as polyurethane, PVC coatings or base fabrics of artificial leather. Test chambers reproduce and accelerate aging outdoors for months or even years in the lab by precisely controlling irradiance, temperature (usually divided into blackboard temperature vs. chamber air temperature), and condensation or spray humidity cycles. Its accelerated aging factor can be estimated by comparing the model with natural exposure data.
Test methodology
Tests to evaluate the aging resistance of leather typically follow a range of international or national standards, such as ISO 4892-3, ASTM G154, and more. The testing process mainly includes four stages: sample preparation, condition setting, cycle cycle, and performance testing.
Sample preparation should ensure that it represents the actual production batch and is cut to size. Condition setting is a critical step in selecting the spectral distribution (e.g., UVA-340 lamp simulating the ultraviolet part of sunlight), irradiation intensity (e.g., 0.76 W/m² @ 340nm), and cycle period according to the final use environment of the leatherette. A typical cycle may include alternating hours of UV light (controlled temperature at e.g. 60°C±3) with several hours of condensation (controlled temperature at e.g. 50°C±3). The total test duration can be set according to requirements, such as 200 hours, 500 hours or more.
The mathematical expression of the test conditions can be used to describe the approximation of the photochemical reaction using the following formula:
ΔP ∝ I × t
where ΔP represents the amount of change in material properties, I represents irradiance, and t represents exposure time. This relationship has reference value when comparing the aging effect under different irradiances.
Evaluation indicators
Before and after the test, the key properties of artificial leather need to be quantitatively evaluated to judge its aging resistance. The main evaluation indicators are shown in the table below:
| Evaluation categories | Specific test items and methods |
| Appearance changes | Chromatic aberration (ΔE) measurement, gloss change, surface chalking rating, crack observation |
| Physical and mechanical properties | Rate of change between tensile strength and elongation at break, tear strength, coating adhesion (peel strength) |
| Chemical structure changes | Fourier transform infrared spectroscopy was used to analyze chemical group changes |
When evaluating, performance retention is typically calculated. Taking tensile strength as an example, the formula for calculating the retention rate is:
R = (Ta / T0) × 100%
where R is the performance retention rate, Ta is the tensile strength after aging, T0 is the initial tensile strength. The higher the retention rate, the better the aging resistance of the material.
Technical considerations
When using the UV aging chamber for evaluation, the following technical points should be noted: First, the irradiance in the chamber needs to be calibrated regularly to ensure uniformity and stability. Secondly, the leatherette sample should be evenly exposed and rotated regularly to reduce possible gradient differences within the box. Finally, the water quality during the condensation stage should meet the requirements of the standard to prevent impurities from affecting the test results.
The interpretation of the results needs to be combined with specific application scenarios. The test results effectively compare the relative weather resistance differences of different formulations, processes, or supplier leatherette materials and provide direction for material improvement. However, it is important to recognize that laboratory accelerated aging testing is simulated and accelerated, and the results are not absolutely equivalent to real outdoor exposure, but they are well correlated. It is often recommended to correlate accelerated test results with outdoor natural exposure data or real-world usage experience to build a more reliable predictive model.
Conclusion
UV aging test chambers are an important tool for evaluating the aging resistance of artificial leather. Through standardized testing methods, rigorous condition control and multi-dimensional performance evaluation, the performance evolution trend of artificial leather in long-term light, humid and hot environments can be efficiently and scientifically predicted. This provides solid technical support for the research and development, quality control and standard compliance verification of artificial leather products, and helps promote the development of the industry towards the production of more durable and reliable products.
References
ISO 4892-3:2016, Plastics — Methods of exposure to laboratory light sources — Part 3: Fluorescent UV lamps.
ASTM G154-16, Standard Practice for Operating Fluorescent Ultraviolet (UV) Lamp Apparatus for Exposure of Nonmetallic Materials.
Wang Jin, Polymer Material Aging and Anti-Aging Technology. Chemical Industry Press.