Antioxidants in plastics are sensitive to oxidative degradation in the process of manufacturing, processing, storage and application of most plastics. Oxygen penetrates into plastic films and can react with most polymers. Causes degradation or cross-linking, which changes the properties of the material.
The oxidation process of polymers is a free radical type chain reaction. Plastic antioxidants are such substances, which can capture active free radicals, generate inactive free radicals, or can decompose polymer hydroperoxides generated during the oxidation process, terminate the chain reaction, and delay the polymer oxidation process. . As a result, the polymer can be processed smoothly and its service life can be extended.
Classification
The chemical structure of plastic antioxidants can be divided into:
⑴. Phenols, including: monophenol, bisphenol, triphenol, polyphenol, hydroquinone, thiobisphenol;
⑵. Amines, including: naphthylamine, diphenylamine, p-phenylenediamine, quinoline derivatives, in addition to phosphites, thioesters and other types.
1. Main use
（1）. Plastic antioxidants are widely used, and can be used as antioxidants such as polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), polyester (PC), polystyrene (PS), ABS resin, fiber resin, etc. .
（2）. Plastic antioxidants can effectively inhibit the aging caused by factors such as light, heat and oxygen.
2. Outstanding advantages
Plastic antioxidants have been widely used in plastics, among which polyolefin and ABS are the most used, followed by polyoxymethylene, polyvinyl chloride and nylon. In use, two or more antioxidants should be fully utilized together, which can produce the advantages of additive or synergistic effects to obtain better benefits.
(1) Additive effect: When the main antioxidant and the auxiliary antioxidant are used together, their respective characteristics are exerted, and the effect is better than that of using one of them alone. The use of a high-concentration antioxidant will cause side effects. When several low-concentration antioxidants are used, side effects can be avoided and additive benefits can be exerted.
(2) Synergistic reaction: When the antioxidants are used together properly and their total efficacy exceeds the sum of their respective efficacy alone, it is regarded as a synergistic effect.
Finally, the oxygen stability of different plastics is different, so some plastics do not need to add antioxidants. Some must add antioxidants. The role of plastic antioxidants is to capture active free radicals and interrupt the chain reaction, in order to delay the oxidation process and speed of plastics. According to the mechanism of action of antioxidants, it is effective for all plastics.
3. How to use
White powder, the addition amount is 0.1-0.5%, directly add the plastic antioxidant into the masterbatch and disperse completely.
