Abstract: The present invention is a process for producing a polyvinyl chloride paste blending resin comprising polymerizing a vinyl chloride-based monomer by a suspension polymerization in an aqueous medium, wherein as a suspending agent, both (A) and (B) are used in a mixing weight ratio (A)/(B) of 99/1 to 50/50, and a total amount of said (A) and said (B) is 0.1 to 1.0 part by weight based on 100 parts by weight of the vinyl chloride-based monomer, said (A) being a partially hydrolyzed water-soluble poly(vinyl alcohol) having a viscosity at 20° C. of 4% aqueous solution by weight of 20 to 110 cps and the degree of hydrolysis of 86 to 99 mol %, and said (B) being a partially hydrolyzed water-soluble poly (vinyl alcohol) having a viscosity at 20° C. of 4% aqueous solution by weight of 5 to 10 cps and the degree of hydrolysis of 70 to 80 mol %.

Abstract: The present invention is a process for producing a polyvinyl chloride paste blending resin comprising polymerizing a vinyl chloride-based monomer by a suspension polymerization in an aqueous medium, wherein as a suspending agent, both (A) and (B) are used in a mixing weight ratio (A)/(B) of 99/1 to 50/50, and a total amount of said (A) and said (B) is 0.1 to 1.0 part by weight based on 100 parts by weight of the vinyl chloride-based monomer, said (A) being a partially hydrolyzed water-soluble poly(vinyl alcohol) having a viscosity at 20.degree. C. of 4% aqueous solution by weight of 20 to 110 cps and the degree of hydrolysis of 86 to 99 mol %, and said (B) being a partially hydrolyzed water-soluble poly(vinyl alcohol) having a viscosity at 20.degree. C. of 4% aqueous solution by weight of 5 to 10 cps and the degree of hydrolysis of 70 to 80 mol %.

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 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.