Why do blow molded products fade?
The fading of blow-molded products is often caused by humans, mainly for the following reasons:
1. Acid and alkali resistance
The fading of blow molding products is often caused by the chemical resistance of the colorant. For example, molybdenum red is resistant to dilute acid, but it is sensitive to alkali, and cadmium yellow is not acid-resistant, which seriously affects the coloring effect of the colorant. , which induces fading.
2. Heat resistance
This is very easy to understand. Heat resistance refers to the degree of discoloration and fading of pigments at high temperatures. For colorant pigments, organic pigments will change their molecular structure at high temperatures and cause fading effects; while inorganic Pigments are relatively heat resistant and more stable.
3. Light fastness
Poor light fastness of the coloring agent will directly lead to fading. Many blow-molded products are outdoor products, so light fastness is the first requirement. According to general industry regulations, the light fastness of outdoor products must not be lower than grade 6, which is an internal product. Generally choose level 4-5.
4. Oxidation resistance
Some inorganic pigments undergo macromolecular dissolution or other modifications after oxidation and gradually fade. The first process is high-temperature oxidation during production and processing, and the second is oxidation when encountering strong oxidants. After the color lake, formamide color paste and iron oxide yellow are mixed and applied, the redness will gradually decrease.