Processing Technology and Control Points of Waste PVC Cable Materials

1, process flow:

The process flow for production of lining special materials and deep processing using waste PVC cable materials is as follows: waste PVC cable material collection → sorting and sifting → crushing and cutting → mixed sampling test → removing magnetic bagging → proportioning mixing → high speed mixing → extruding Smelting → Granulation Cooling → Air Bagging → Sampling Test → Extrusion Lining → Sampling Test.

2, production control points

Process parameters are the core elements of extrusion granulation. If the process parameters are not correct, it is difficult to produce qualified products even with excellent formulations. Whether or not the setting of process parameters is reasonable will directly affect whether the semi-finished products are fully mixed and uniformly plasticized, and whether the preliminary pre-plasticizing effect can be achieved; otherwise, not only the appearance and performance of the products are caused, but also during deep processing (extruding the inner lining of the cable). It is easy to produce abnormal quality.

In the process of collection, crushing and demagnetization of waste PVC cable materials, foreign materials should be carefully selected, and materials such as PE, XLPE and PVC cable tapes must not be mixed, and copper, aluminum and other metal and wood chips must be separated to ensure that used PVC cable materials are clean. No debris.

After the broken and bagged waste PVC cable material is mixed and mixed for 4 to 5 minutes at a mixing temperature of 70 to 85°C, the uniformly mixed PVC material is added to the TY75-180 double-stage twin-screw extrusion granulation unit for extrusion granulation. The extrusion temperature is (150 ± 5) °C. Granulated pellets need to be dispersed and cooled to prevent pellets from sticking.

In the secondary granulation of used PVC cables, the filter should be replaced regularly and the exhaust gas should be checked regularly. Normally, 3 to 4 layers of 150 to 250 μm mesh (60 to 100 mesh) stainless steel strainers (or copper strainers) are replaced every 2 to 3 hours to prevent the strainer from being broken by impurities and coke in the waste PVC cable material. When the inner lining layer is mixed with impurities, the spark rate of the cable jacket is high and a voltage breakdown occurs.

It is necessary to intensify the inspection of the exhaust device to prevent the vacuum pressure from decreasing due to the leakage of the exhaust device, and it is not easy to discharge decomposition products such as HCl, CO2, and CO, and water vapor, resulting in the formation of pores and pinholes in the inner liner, and the poor performance of the process. The appearance of the cable product is rough and not smooth.

The special materials for PVC lining produced by secondary granulation shall be used in a timely manner and should not be placed for too long to avoid moisture absorption and moisture absorption. It is recommended that the time for placement should not exceed 1 month.