s are generally divided into hard pipes and hoses, such as drain pipes, threading pipes, UPVC pipes, etc. These are hard pipes; and hoses are often used on the surface of floors, ceilings, and leather. Because PVC hose contains plasticizer, its physical properties are relatively poor and its application range is limited. The PVC hard pipe does not contain plasticizers, so it is easy to form and has better physical properties, so it is one of the plastics with relatively large output at present. After the pipe has been used for a period of time, yellowing will appear, and for this problem, the root cause must be found.
First of all, it is necessary to determine whether it is caused by the processing temperature being too high. If the temperature is too high, the paste will turn yellow. If the temperature is too high, you need to appropriately lower the temperature of the barrel material, which can improve the yellowing phenomenon. Secondly, it is necessary to determine whether the yellowing is caused by the decomposition of PVC. If it is, the formula and process should be improved. And check if the heat stabilizer has been added enough. Check whether the amount of added fluorescent whitening agent is not enough, or whether the selected fluorescent whitening agent is not suitable. These can be tested by themselves
PVC pipes are made of PVC plastic. PVC plastic has excellent resistance to oxidants, reducing agents and strong acids, but PVC plastics are easily corroded by concentrated oxidizing acids such as concentrated sulfuric acid and concentrated nitric acid, and are not suitable for aromatic hydrocarbons, Where chlorinated hydrocarbons come into contact. The melting temperature is a very critical parameter in the production and processing of PVC. If this parameter is used improperly, it will cause the problem of material decomposition. It is recommended to use the fluorescent whitening agent LP-127 for PVC pipes. Its appearance is light yellow crystalline powder, which has very good anti-ultraviolet effect, especially for pipes and sheets. The dosage is small, and the key is higher whiteness. Yellow again.