Do you know what causes the fading of blow molded products? Let’s talk about Jinhua blow molding, Jinhua injection molding, and Jinhua plastic toy manufacturers in detail below. The main elements are heat resistance, light resistance, acid and alkali resistance, and oxidation resistance.

1. Heat resistance

The thermal stability of a pigment refers to the degree of thermal weight loss, discoloration, and fading of the pigment at the processing temperature. Inorganic pigments are composed of metal oxides and salts, which have good thermal stability and high heat resistance. The pigments of organic compounds will undergo molecular structure changes and a small amount of differentiation at a certain temperature. Especially for PP, PA and PET products, the processing temperature is above 280℃. When choosing the coloring agent, one should pay attention to the heat resistance of the pigment, and on the other hand, consider the heat resistance time of the pigment. Generally, the heat resistance time is required to be 4— 10rain.

2. Lightfastness

The light fastness of the coloring agent directly affects the fading of the product. For outdoor products exposed to strong light, the light fastness (light fastness) rating of the coloring agent used is a primary policy. The light fastness level is poor, and the product will quickly fade during use. The light resistance grade selected for weather-resistant products should not be lower than grade 6, and grades 7 and 8 are used, and grades 4 and 5 are available for indoor products. The light resistance function of the carrier resin also has a greater impact on the color change. The molecular structure of the resin changes and fades after being irradiated by ultraviolet rays. Add light stabilizers such as ultraviolet absorbers in the mother guess, which can be used for coloring agents and light-fastness functions of colored blow-molded products.

Three, acid and alkali resistance

The fading of colored blow molding products is related to the chemical resistance of the coloring agent (acid and alkali resistance, oxidation-reduction resistance). For example, molybdenum chrome red is resistant to dilute acid, but is active to alkalis, and cadmium yellow is not acid resistant. These two pigments and phenolic resin have a strong reducing effect on certain coloring agents, which seriously affects the heat resistance and weather resistance of the coloring agent. fade.

4. Antioxidant

Some organic pigments undergo macromolecular degradation or other changes after oxidation and gradually fade. This process is high temperature oxidation during processing, and oxidation when encountering strong oxidants (such as chromate in chrome yellow). After the lake, azo pigment and chrome yellow are mixed and used, the red color will gradually fade.