Common problems in the production of chlorinated polyethylene cable - the surface of the cable sheath is rough and not smooth

Chlorinated polyethylene (CPE) is produced by chlorination of high-density polyethylene (HDPE), the molecular chain is saturated structure, and the vulcanization system generally uses the peroxide system, so it has good storage safety and processing safety. It has been proved by long-term practice that it is more convenient to use than traditional rubber.

Chlorinated polyethylene still has some characteristics of plastics, and when used for cable extrusion, it still requires a higher plasticizing temperature than traditional rubber. For customers who do not understand the characteristics of CPE, if they do not grasp the appropriate process parameters and follow the traditional rubber extrusion process to produce cables, problems such as too low temperature and poor plasticization will occur.

Chlorinated polyethylene is powdered, easy to absorb moisture for a long time, resulting in excessive moisture, so that products have bubbles or micropores, etc., southern humid climate is more likely to have this phenomenon. In addition, the production of rubber cables is more complex than that of plastic cables, affected by many factors such as equipment conditions, process conditions, operating level, technical level, etc., there are more problems in the extrusion process, and it is not easy to solve properly.

The surface of the cable sheath is rough and not smooth:

The influencing factors of this phenomenon need to be considered from three aspects: extrusion pressure, extrusion temperature, and compound quality.

(1) The screw length-diameter ratio is too short, the compression ratio is small, and the rubber pressure is not enough.

(2) The selection of mold core and mold sleeve is unreasonable.

(3) The processing accuracy of the die sleeve is not enough or the material is not good, and the damage is caused after corrosion.

(4) Extruder temperature setting is too low, plasticizing is not good.

(5) The viscosity of the mixed rubber Mooney is too high.

(6) The fineness of the mixed rubber filler is not enough.

(7) The mixing effect is poor and the dispersion is uneven during the production of mixed rubber.

(8) The selection of chlorinated polyethylene is not suitable.

The first four points are the equipment and process control problems of the cable manufacturer. In addition to the screw replacement has a certain difficulty, the rest can be solved by adjusting accordingly. Select suitable mold core and mold set, increase extrusion temperature, etc.

The last four points are the problems of mixing rubber, which can be solved by adjusting the formula, selecting raw materials with high fineness and increasing the mixing time. It should be emphasized that the selection of chlorinated polyethylene: the chlorinated polyethylene suitable for the production of rubber sheathing cables should be the rubber type (B type) with low Mooney viscosity, which has excellent comprehensive physical properties and good processing performance. High molecular weight chlorinated polyethylene Mooney viscosity, plasticization is difficult, filling amount is small, easy to cause rough surface, uneven diameter, cooked glue, gum and other defects. Rubber CM with Mooney viscosity of 60~80 is widely used abroad for the production of wire and cable.