Formula composition of chlorinated polyvinyl chloride (PVC-C) pipes - 1

Chlorinated polyvinyl chloride resin (hereinafter referred to as CPVC resin) was successfully developed in 1958 by BFGoodrich from USA, which is the product of chlorination of polyvinyl chloride resin (PVC resin).

After chlorination of PVC, the chlorine content can be increased from 57% to 64% - 75%, with the increase in chlorine content, the corresponding temperature resistance, rigidity, chemical resistance, flame retardant, smoke and so on can be enhanced. However, CPVC resin melt viscosity increases, brittleness increases, impact strength decreases, thermal stability decreases, to the CPVC extrusion process brings great difficulty, at the same time, if the process not properly controlled will produce a large number of HCl gas and make the processing equipment and molds are seriously corroded.

Therefore, the extrusion processing of CPVC resin has been the focus of discussion. In the CPVC processing, "plasticization" is the key, therefore, how to get a good quality of plasticization from the formula, equipment and process technology, is the key to CPVC resin processing.

So firstly Let's talk about the Chlorinated polyvinyl chloride (PVC-C) pipe formula composition.

1. Heat stabilizer

CPVC resin is easier to decompose than PVC in the process, so it is necessary to add more heat stabilizers than PVC, when making the trial production, the dosage of stabilizer can be added in accordance with the dosage of PVC added 1.5 to 2.5 times, and then according to the trial production of the appropriate increase or decrease.

The general principle is: heat stabilizer should not be added too much, otherwise it will affect the plasticization of CPVC resin.

Basically, most of PVC heat stabilizers can be used to process CPVC, such as Lead salt stabilizers, Calcium Zinc stabilizers, composite Lead stabilizers, metal soap stabilizers and liquid organoTin stabilizers, etc., in the many heat stabilizers, when the pipe has different special requirements, there is a difference in the selection.

Organic Tin stabilizers should be used when producing sanitary CPVC pipes; liquid organic tin stabilizers should be avoided as much as possible when producing pipes with requirements for temperature resistance; calcium stearate should not be added when producing high-impact pipes.

At present, the most used stabilizer is liquid organoTin stabilizer.

(To be continued...)