Method for polymerizing vinyl halide polymers

Claim 2

allowing a portion of the monomers to escape from the body of the polymerization mixture as a vapor phase and returning the condensate to said body to provide cooling concurrently with liquid-phase heat exchange during the bulk of the polymerization cycle;

Claim 3

The method of claim 1 wherein said heat-exchange coNtact is essentially the sole heat exchange step employed until about 10-20 percent of the polymerizable monomer in said monomer formulation is converted to polymer and wherein said inert liquid is water.

Claim 4

The method of claim 21 wherein said dispersing agent formulation is a mixture of dispersing agents comprising a water-soluble cellulose ether selected from the group consisting of methyl cellulose, ethyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose and mixtures thereof; a partially hydrolyzed polyvinyl acetate; and about 0.1- 0.25 percent of a sorbitan fatty acid ester surfactant, based upon the weight of polymerizable monomers in the monomer formulation, the fatty acid chain of the sorbitan ester containing 12 to 18 carbon atoms, the polyvinyl acetate and cellulose ether being included in a ratio of their respective weights ranging from about 0.3 to 3.0:1 and the combination thereof being present in said polymerization mixture in an amount of about 0.04 to 0.1 percent based upon the weight of polymerizable monomers in said formulation.

Claim 5

while concurrently extracting heat from said mixture by said liquid-phase heat exchange and vapor-phase condensation, introducing inert liquid into said polymerization mixture at about the point of conversion of the monomers at which the polymerization reaction accelerates rapidly, the temperature of said inert liquid being lower than the batch temperature existing in the body of said mixture, said point of acceleration of the polymerization reaction being at about 65 to 80 percent conversion of the polymerizable monomers in said monomer formulation to polymer with said low temperature inert liquid introduced serving to help control the temperature at and after the point of rapid acceleration of the polymerization reaction at which viscosity of the polymerization mixture is increased; D. allowing the polymerization reaction to continue after the rapid acceleration to the desired degree of completion of conversion of monomers to polymer; E. terminating the polymerization reaction; and F. withdrawing the polymerization mixture from the reaction vessel and recovering the polymer from said polymerization mixture.

Claim 6

0.005 to 1.0 percent, based upon monomer, of a highly active polymerization initiator having a half-life of less than 5 hours at 50* C. in 1,2-dichloroethane, and

Claim 7

water B. adjusting the temperature of said polymerization mixture within said reaction vessel to a desired polymerization temperature in the range from about 45* to 70* C. to effect polymerization of the polymerizable monomers therein; C. maintaining said polymerization mixture under substantially isothermal conditions during the polymerization of the monomer therein, the maximum temperature fluctuation from the desired polymerization temperature in said polymerization mixture being limited to 2.5* C. during the polymerization reaction and until said reaction is substantially complete by a combination of heat-exchange steps comprising:

Claim 8

The method of claim 3 wherein said surfactant is included in an amount ranging from about 0.15 to 0.18 percent based upon the weight of polymerized monomers, wherein said polyvinyl acetate has a residual acetate content of about 20 to 45 weight percent, and wherein said surfactant is a sorbitan monoester selected from the group consisting of the esters of lauric acid, oleic acid, palmitic acid, stearic acid and mixtures of said acids, and wherein the combination is present in an amount of about 0.07 to 0.09 percent by weight of the polymerizable monomers.

Claim 9

The method of claim 1 wherein the said polymerization initiator is selected from the group consisting of dialkylperoxydicarbonates, acyl persulfonates, symmetrical peroxides and symmetrical azo compounds and mixtures thereof.

Claim 10

The method of claim 1 wherein a portion of said monomer formulation is substantially continuously introduced into said water during at least a portion of the polymerization reaction.