Analysis of the causes and solutions for the fading of plastic products
Plastic colored products can be discolored by a variety of factors. The fading of plastic colored products is related to the light resistance of the pigment, the dye, the oxidation resistance, the heat resistance, the acid and alkali resistance, and the properties of the resin used. According to the processing conditions and use requirements of plastic products, the above properties of the desired pigments, dyes, surfactants, dispersants, carrier resins and anti-aging additives should be comprehensively evaluated before the masterbatch is produced. 1. Lightfastness The lightfastness of the colorant directly affects the fading of the product. For outdoor products exposed to strong light, the lightfastness (lightfastness) rating of the colorant used is an important indicator. The lightfastness is poor and the product is used very quickly. fade. The light resistance grade of weathering products should be no less than six grades, preferably seven or eight grades, and four or five grades of indoor products. The light resistance of the carrier resin also has a great influence on the change of color, and the molecular structure of the ultraviolet-induced resin is changed to fade after irradiation. By adding a light stabilizer such as a UV absorber to the master batch, the light resistance of the colorant and the colored plastic article can be improved. 2. The thermal stability of a heat-resistant pigment refers to the degree of heat 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. Especially for PP, Pa, PET products, the processing temperature is above 280 °C. On the one hand, the coloring agent should pay attention to the heat resistance of the pigment. On the one hand, the heat resistance time of the pigment should be considered. Generally, the heat resistance time is 4-10rain. . 3. Antioxidant Some organic pigments gradually degrade after macromolecular degradation or other changes after oxidation. The first process is high temperature oxidation during processing, and the second is the occurrence of strong oxidants (such as chromate in chrome yellow). Oxidation. When the lake, azo pigment and chrome yellow are mixed, the red color will gradually decrease. 4. The fading of acid and alkali resistant colored plastic products is related to the chemical resistance (acid and alkali resistance, oxidation and reduction resistance) of the colorant. For example, molybdenum chrome red is resistant to dilute acid, but sensitive to alkali, and cadmium yellow is not resistant to acid. 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. Ultra High Pressure Double Plug Cement Head High Pressure Double Plug Cement Head,Float Ore Shoe,Oilfield Cement Mechanical,Parabow Cementing Tools Puyang Junhong Rubber Co., Ltd. , https://www.pyjhxs.com
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