The chemical process for making PVC involves three steps: first, production of
the monomer, vinyl chloride; then the linking of these monomer units in a polymerisation
process; and finally the blending of the polymer with additives.
Pressure is applied to vinyl chloride (dispersed in water as a suspension or an emulsion)
in high pressure chambers at temperatures of 50-70°C. The role of water is to remove
and control the heat given off in the polymerisation process. PVC forms as tiny particles
which grow and when they reach a desired size the reaction is stopped and any
unreacted vinyl chloride is distilled off and re-used. The PVC is separated off and dried to
form a white powder.
In the early 1970’s it was
discovered that prolonged exposure to
very high concentrations of VCM could PVC Manufacture
result in a rare form of liver cancer. All Flow Diagram
plants currently in operation employ
designs which ensure that the work RAW MATERIALS
force are protected against
this risk. NATURAL SALT ELECTRICITY GAS
Modern techniqies for the stripping of
unreacted monomer from the polymer
ensure that there are no problems
either during processing or in end uses
such as food packaging. “CRACKER” PROCESS
ELECTROLYSIS PROCESS
PVC is a very versatile
compound and the fact that it can
be combined with a wide range of other ETHYLENE CHLORINE GAS GAS
substances, including other polymers, VCM CAUSTIC
to give an exceptional range of HYDROCARBONS PLANT SODA AND OIL HYDROGEN
properties. GAS
HYDROCHLORIC ACID
The other substances are mixed with
the PVC polymer and hot processed. PVC PLANT
Thus, the flexibility of the end
product can be controlled accurately
with the use of plasticisers.
Alternatively plasticiser-free rigid
shatter resistant bottles or heavy duty
water / sewerage pipes can be
manufactured from PVC. BLENDER
PVC can be formulated to meet
specific requirements and the
possibilities of colour are boundless.
PVC ENDPRODUCT
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