Factors affecting the fading of plastic EVA products

Nowadays, the development of EVA products represented by EVA bags is very good. What are the factors that affect the fading of plastic EVA products?

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 properties of the resin used. According to the processing conditions and usage requirements of plastic products, the required pigments, dyes, surfactants, surfactants, dispersants and anti-aging additives in the production of masterbatch.

1. The fading of acid and alkali resistant 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 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 colorants and causing fading.

2. Antioxidation: After oxidation, some organic pigments will undergo macromolecular degradation or other changes and gradually fade. This process involves high-temperature oxidation during processing and oxidation when encountering strong oxidants (such as chromate in chrome yellow). When lakes, azo pigments and chrome yellow are mixed, the red 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. Inorganic pigments are composed of metal oxides and salts and have good thermal stability and high heat resistance. Pigments of organic compounds will undergo molecular structure changes 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 a colorant, on the one hand, we should pay attention to the heat resistance of the pigment, and on the other hand, we should consider the heat resistance time of the pigment. Heat resistance time is generally 4-10rain. .

4. The quality of light fastness directly affects the fading of the product. For outdoor products exposed to strong light, the required lightfastness (lightfastness) rating of the colorant used is an important indicator. The lightfastness rating is poor and the product will fade quickly in use. fade. The light resistance grade selected for weather-resistant products should not be lower than grade six, which is grade seven or eight. For indoor products, grade four or five can be selected. The lightfastness of the carrier resin also has a large impact on color change. The molecular structure of the resin changes and fades when exposed to UV light. Adding light stabilizers such as ultraviolet absorbers to the masterbatch can improve the light resistance of colorants and colored plastic products.