PVC Hard Pipe Production Process of PVC Pipe Production Line

Common PVC products are PVC pipes, which account for a large proportion of plastic pipes. PVC pipes can be divided into two types: PVC hoses and PVC hard pipes (usually called UPVC, or RPVC).

PVC hard pipe (UPVC pipe) is made by mixing PVC resin with stabilizers, lubricants and other additives, then granulating and molding on a PVC production line extruder. It can also be extruded with powder at one time. UPVC pipe is easy to cut, weld, bond, heat and bend, so it is very convenient to install and use.

1. Raw material selection for UPVC pipe production on PVC pipe production line

In the production of PVC production line for hard pipes, the resin should be SG-5 resin with a lower degree of polymerization. The higher the degree of polymerization, the better its physical and mechanical properties and heat resistance, but the poor fluidity of the resin brings certain difficulties to processing, so it is generally used Sc-5 resin with viscosity of (1.7~1.8)×10-3pa·s is suitable.

The hard pipe of PVC production line generally uses lead-based stabilizer, which has good thermal stability. Tribasic lead is commonly used, but its lubricity is poor, and it is usually used together with lead and barium soap with good lubricity. When processing hard pipes, the choice and use of lubricants are very important. It is necessary to consider internal lubrication and reduce the intermolecular force to reduce the viscosity of the melt to facilitate forming, and also consider external lubrication to prevent the melt from adhering to the hot metal and make the product The surface is bright. Metal soaps are generally used for internal lubrication, and low-melting waxes are used for external lubrication. The filler mainly uses calcium carbonate and barium. Calcium carbonate makes the surface of the pipe good. Barium can improve the formability and make the pipe easy to shape. Both can reduce the cost. However, too much use will affect the performance of the pipe. Pressure pipes and corrosion-resistant pipes are the best It's better to add no or less fillers.

2. The process flow of UPVC pipe production on PVC pipe production line

The UPVC pipe molding PVC production line uses SG-5 PVC resin, and adds stabilizers, lubricants, fillers, pigments, etc. These raw materials are kneaded according to the formula after appropriate treatment. If the extrusion pipe uses a single screw extruder, The kneaded powder should also be formed into pellets, and then extruded; if a twin-screw extruder is used, the powder can be directly used for forming.

In addition, in the production of PVC production line, it can be different from the process shown above, that is, the powder is used to directly extrude the pipe without pelletizing, but two points should be paid attention to:

First, it is best to use a twin-screw extruder for direct powder extrusion molding, because powder and pellets have one less mixing and shearing plasticizing process, so the twin-screw extruder can strengthen the shearing and plasticizing process to achieve the desired effect;

Second, because the pellets are denser than powders and have poor heat and heat conduction, the processing temperature of the powders can be about 10°C lower than the processing temperature of the corresponding pellets.