A process for preparing a vinyl chloride paste resin comprising the steps
of homogenizing a vinyl chloride monomer in an aqueous medium together
with an oil-soluble polymerization initiator to form a first aqueous
dispersion, and subjecting the first dispersion to a micro-suspension
polymerization wherein a second aqueous dispersion containing a vinyl
chloride monomer and a surface active agent is added to the reaction
system in such a manner that the addition is started after starting the
polymerization but by the time the polymerization conversion of the
initially charged monomer reaches 30%, and is terminated by the time the
polymerization conversion of the initially charged monomer reaches 95%.
The process has an improved productivity since the heat removing area of a
jacket of a reactor is prevented from lowering during the polymerization
to increase the amount of heat removed and since the polymer yield per
unit volume of the reactor is increased.
