Release time：2021-07-09
We often encounter some household appliances in our daily life. After using them for a long time, we will find that the outermost plastic shell changes from milky white to beige, and even we often find that if the temperature of the air conditioner shows, the characters also turn yellow. Let's understand what happened inside.
Let's first talk about the yellowing of LED module or LED digital tube digital screen products. Most of our LED digital enclosures are PC, PPO, ABS or PC ABS. Those with the lowest cost belong to ABS. In order to reduce the material cost, some plastic digital consumer manufacturers will consider ABS materials or add ABS components to other main plastics in the selection of raw materials. If the LED emits white light and blue light, the ABS plastic shell will definitely turn yellow after being used for a certain number of years.
In addition, the most common shell of our household appliances, such as air conditioners, changes from bright white to yellow and dim after being placed at home for a period of time. The age of yellowing varies according to different manufacturers. The most important thing is that most of the plastic shells of this kind of white appliances have ABS raw materials or contain ABS raw materials. Let's talk about in detail why ABS raw materials turn yellow?
Generally speaking, the yellowing of ABS recycled plastic granular products is caused by the aging or degradation of materials. Generally, it is caused by aging (degradation). Due to the existence of side groups on polypropylene, its stability is not good, especially under the condition of light. Ordinary light stabilizer.
(1) As for ABS regenerated particles, because there is no side base, there are not many yellowing conditions in the initial stage of ordinary processing or application. ABS regenerated particles will turn yellow, which is closely related to the formula of the product.
(2) Yellowing may be related to damp heat oxidation and ultraviolet light. It will be heated (electric heating) in the process of application. If it is wet, it is easy to be further oxidized, resulting in yellowing and embrittlement. Or due to the problem of ABS processing technology, the long residence time during injection molding leads to the rapid time request of ABS processing, short cycle time, and mold temperature of 60-70), leading to degradation.
(3) Simply put, the main advantage of the air outlet of ABS data is that it will not condense, it will not deform at high temperature, and it is elegant and beautiful (the thermal deformation temperature of ABS can reach 95 degrees). In the process of consuming ABS tuyere profiles, antioxidants and light stabilizers were added, which weakened the appearance yellowing caused by UV absorption.
(4) ABS oxidation resistance is not very good, and it is easy to turn yellow in the environment of light or wind and rain. The condition without additives is that the yellowing is very serious after a long time of illumination, even if it is white, so pay special attention to the elements of illumination when storing ABS particles.
If the yellowing ABS is expected to turn white, the physical method is to scrape off the yellowing layer on the surface, but this will cause great damage to the plastic. Even if it turns white successfully, it will be full of scratches; The chemical method is to use oxidants to stop the recovery of plastics. This method is more thorough, and the damage to the appearance of plastics is relatively small. In theory, plastic anti yellowing agents can also be used for white mobile phones and other plastic materials, but it has no essential significance for our daily white appliances.
After the above understanding of the principle of ABS material, our colleagues in the industry should understand that it is best to avoid ABS material components when selecting materials for the shell of light-emitting digital screen, especially in the condition of white light and blue light and in the environment of high temperature and high humidity. However, at present, the plastic industry of the shell of household appliances is also developing new materials with more yellowing resistance on the premise of cost. I believe that it will soon be widely used in the market.
Well, this time we will first understand the choice of plastic raw materials in the plastic home appliance shell industry. If you have any suggestions or questions about the plastic home appliance shell industry, please leave a message in the comment area or pay attention to private chat!
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