Introduction of PVC pipe extrusion production process and operation Ⅰ

PVC plastic pipes include hoses and hard pipes, which account for a large proportion of plastic pipes. In the production of PVC plastics, different additives are added according to different uses, and the added components are different. The pipe products show different physical and mechanical properties and are used for different occasions.

RPVC pipe has good chemical corrosion resistance and good insulation. The main advantages are that it is easy to cut, weld, bond, and bend when heated. It is very convenient to install and use. It mainly transports various fluids and is used as wire sleeves. RPVC pipe is made by mixing PVC resin with stabilizers, lubricants and other additives, and extruding it after granulation. It can also be extruded from powder at one time.

SPVC pipe has excellent chemical stability, excellent electrical insulation and good flexibility and colorability. It is made of PVC resin with a large amount of plasticizer, a certain amount of stabilizer, and other additives, and is extruded after granulation. Molded manufacturing. Spvc pipes are often used to replace rubber pipes to transport liquids and corrosive media, and are also used as cable casings and wire insulation pipes.

1. Correct selection of raw materials and formula

Generally, SG-5 resin with viscosity (1.7~1.8)×10-3Pa·s is suitable for hard pipe production. Tribasic lead is usually used as stabilizer, which has good thermal stability and is used with lead and barium soaps with good lubricity to increase lubricity. When processing hard pipes, it is necessary to consider internal lubrication to reduce the intermolecular force, so that the viscosity of the melt is reduced to facilitate molding, and external lubrication must be considered to prevent the melt from sticking to the hot metal and make the surface of the product bright. Metal soaps are generally used for internal lubrication, and low-melting waxes are used for external lubrication. Calcium carbonate and barium (barite powder) are mainly used as fillers. Calcium carbonate can improve the surface performance of the pipe, and barium can improve the formability and make the pipe easy to shape. It is best to add no or less filler to the pipe and corrosion-resistant pipe.

2. Points to note in the process flow

The molding of RPVC pipe uses SG-5 PVC resin, and adds stabilizers, lubricants, fillers, pigments, etc. These raw materials are properly treated and kneaded according to the formula. The PVC small pipe extruder of Huade Plastic Machinery adopts twin-screw . Extruder, which can be directly molded with powder.

In addition, when using powder to directly extrude the pipe without granulation, two points should be paid attention to: First, it is best to use a twin-screw extruder for direct extrusion of the powder, because the powder is one less than the granule. Mixed shearing and plasticizing process, so the use of twin-screw extruder can strengthen shearing and plasticizing to achieve the desired effect; secondly, because the pellets are denser than the powder, the heat and heat conduction are poor, so the processing temperature of the powder is comparable. The processing temperature of the corresponding pellets is preferably about 10°C lower.