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Factors affecting the fading of plastic products

Update:29 Sep 2019
Summary:

According to the data and practice, there are many fact […]

According to the data and practice, there are many factors that affect the fading of plastic products. The fading of plastic color products is related to the light resistance, anti-oxidation, heat resistance, acid and alkali resistance of the pigments and the properties of the resins used. In the production of masterbatch, the above properties of the desired pigments, dyes, surfactants, dispersants, carrier resins and anti-aging additives are comprehensively evaluated. The following are the reasons for the conventional color change and logistics performance. For the reference of the parents.

1. Lightfastness

The light fastness of the colorant directly affects the fading of the product. For outdoor products exposed to strong light, the light fastness (lightfastness) grade requirement of the colorant used is an important indicator, and the light resistance grade is poor, and the product will quickly fade in use. So this is why, for example, anti-glare panels on the highway, water horses, etc., after a few years, the color of the sun will fade, but in the case of blow molding, quantitative anti-UV components will be added to ensure Product color retention time persistence.

2. 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. The inorganic pigment is composed of metal oxides and salts, has good thermal stability and high heat resistance. However, the pigment of an organic compound undergoes a change in molecular structure and a small amount of decomposition at a certain temperature. Actually, we need it in the production process. If it is a plastic product that needs high temperature heating, it is necessary to select a pigment with more heat resistance to ensure color discoloration, fading, and ensure the overall appearance of the product.

3. Antioxidant

Some organic pigments gradually degrade after macromolecular degradation or other changes after oxidation. The first process is high temperature oxidation in processing, and the second is oxidation of strong oxidants (such as chromate in chrome yellow). When the lake, azo pigment and chrome yellow are mixed, the red color will gradually decrease.

4. Acid and alkali resistance

The fading of colored plastic products is related to the chemical resistance (acid and alkali resistance, oxidation and reduction resistance) of the colorants. For example, molybdenum chrome red is resistant to dilute acid, but sensitive to alkali, cadmium yellow is not acid resistant. These two pigments and phenolic resin have strong reduction effect on certain colorants, which seriously affect the heat resistance, weather resistance and fading of the colorant.