Some friends have encountered such a situation. I don’t know why. The color of this game bag has faded after being used for a long time. I originally thought it was a material that will not fade, but now it has faded. So let’s take a look at the reasons why. What is the reason for the fading of EVA game bags?
Factors affecting the fading of plastic EVA products. The fading of plastic colored products is related to the light resistance, oxygen resistance, heat resistance, acid and alkali resistance of pigments and dyes, and the characteristics of the resin used. According to the processing conditions and usage requirements of plastic products, the above-mentioned properties of the required pigments, dyes, surfactants, dispersants, carrier resins and anti-aging additives should be comprehensively evaluated during the production of masterbatch before selection.
1. Acid and alkali resistance The fading of colored plastic products is related to the chemical resistance of the colorant (acid and alkali resistance, redox resistance).
For example, molybdenum chromium red is resistant to dilute acid, but is sensitive to alkali, and cadmium yellow is not acid-resistant. These two pigments and phenolic resin have a strong reducing effect on certain colorants, seriously affecting the heat resistance and weather resistance of the colorants and causing fading.
2. Antioxidation: Some organic pigments gradually fade due to degradation of macromolecules or other changes after oxidation.
This process involves high-temperature oxidation during processing and oxidation when encountering strong oxidants (such as chromate in chromium yellow). When lakes, azo pigments and chrome yellow are mixed, the red color will gradually fade.
3. Thermal stability of heat-resistant pigments refers to the degree of thermal weight loss, discoloration, and fading of the pigment under processing temperature.
The ingredients of inorganic pigments are metal oxides and salts, which have good thermal stability and high heat resistance. Pigments made from organic compounds will undergo changes in molecular structure and a small amount of decomposition at a certain temperature. Especially for PP, PA, and PET products, the processing temperature is above 280°C. When selecting colorants, on the one hand, we must pay attention to the heat resistance of the pigment, and on the other hand, we must consider the heat resistance time of the pigment. The heat resistance time is usually 4-10rain. .
Post time: Jul-12-2024