Abstract: In a process for the microsuspension of emulsion polymerization of vinyl chloride using a polymerization apparatus equipped with an agitator the improvement where the ratio (H/D) of the effective height (H) of the apparatus to the effective inner diameter (D) of the apparatus is 4 or more.

Abstract: In a process for the microsuspension or emulsion polymerization of vinyl chloride using a polymerization apparatus equipped with an agitator the improvement where the ratio (H/D) of the effective height (H) of the apparatus to the effective inner diameter (D) of the apparatus is 4 or more.

Abstract: A method for purifying a crude high-molecular weight substance containing an alkali metal compound by extracting the alkali metal compound with water is disclosed, which comprises stirring a mixture comprising said crude high-molecular weight substance and water in a high-speed stirring tank to extract the alkali metal compound into an aqueous phase and separating the high-molecular weight substance phase and the aqueous phase from each other by continuous centrifugation. An alkali metal compound as an impurity can be efficiently removed with small-sized equipment in a short time.

Abstract: The present invention provides a process for producing vinyl chloride resin in suspension polymerization of vinyl chloride monomer by the use of a polymerization reactor equipped with a reflux condenser using an improved brumagine-type impeller equipped with auxiliary blade/s, and polymerization is started in a range of 0.8 to 1.0 of the water/monomer ratio, polymerization temperature is raised to 3.degree. to 10.degree. C. at polymer conversion being not more than 50 weight percent, with water being added in the course of polymerization not more than making up for the volumetrical contraction resulting from the progress of polymerization so that upon completion of polymerization the water/monomer ratio is controlled in a range of 1.0 to 1.4. The polyvinyl chloride resin obtained by the present process is superior in quality such as high bulk density and little fish eye with high productivity.

Abstract: The present invention provides a process for producing vinyl chloride resin in suspension polymerization of vinyl chloride monomer by the use of a polymerization reactor equipped with a reflux condenser wherein a nonionic surface active agent having a HLB value of 6-14 is added upon initial charging of reactants, polymerization is started in a range of 0.8 to 1.0 of the water/monomer ratio, the polymerization temperature is raised 3.degree. to 10.degree. C. when polymer conversion is not more the 50 weight percent, with water being added in the course of polymerization to not more than make up for the volumetrical contraction resulting from the progress of polymerization so that upon completion of polymerization the water/monomer ratio is controlled in a range of 1.0 to 1.4. The polyvinyl chloride resin obtained by the present process is superior in quality such as high bulk density and little fish eye content with high productivity.

Abstract: A reflux condenser attracts attention from the standpoints of improvement in productivity by increase in cooling capacity as well as saving in energy, and recently, it is frequently employed in particularly large-sized polymerization reactors. But, the well-known cooling method has a problem that the overall heat transfer coefficient of condensers lowers with the progress of polymerization to result in the reduction of heat-removing capacity and reduction of the stability of polymerization temperature control. In order to solve the above problems, in the present invention the temperature is controlled with the heat amount removed by the condenser as a control variable, coupled with intermittent purge of a part of the unreacted monomer from the reflux condenser.

Abstract: A process for polymerizing vinyl chloride is disclosed which comprises coating prior to the polymerization the surfaces of a polymerization reactor, agitator blades and a reflux condenser with a reaction product obtained by the reaction of a phenolic compound and an aromatic aldehyde, said reaction product having an average molecular weight of from 3,000 to 10,000. Not only is the polymer scales formation prevented surprisingly, but a high quality product substantially free from fish eyes is obtained.

Abstract: A method for production of vinyl chloride resin is provided, in which vinyl chloride or a monomeric mixture containing vinyl chloride as a major ingredient is polymerized, while controlling the operation of a reflux condenser provided at a polymerization vessel by supplying hot water or steam and then cooling water to the side of cooling water of the condenser, whereby bubbling is suppressed. The method provides outstanding advantages, such as, a high quality product improved with respect to fish eyes, high productivity, a shortened polymerization time, and a savings in steam for heating.