Process for the suspension polymerization of polyvinyl chloride
AssigneeDiamond Shamrock Plastics Corporation
InventorWilliam D. Peeples
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Abstract
The present invention relates to the manufacture of suspension grade PVC and other vinyl chloride resins of superior overall quality, especially in that they possess both high bulk densities and excellent porosities as shown by their fast absorption rates for hot liquid plasticizers. The key feature of the suspension polymerization process involved is the use of a particular combination of two types of suspending agents throughout the process, namely a polyvinyl alcohol resin with a hydrolysis level of about 68 to about 78 percent together with a hydroxypropyl cellulose ether with a molar substitution of between about 2 and about 4.
Claims9
A process for the suspension polymerization in an aqueous medium at temperatures between about 30.degree. and about 80.degree. C. of vinyl chloride monomer with or without suitable comonomer in the presence of an oil soluble initiator wherein said aqueous medium contains from about 0.02 to about 0.75 parts per 100 parts, by weight, of total monomer of a combination of suspending agents composed of (a) a polyvinyl alcohol resin (PVA) with a hydrolysis level of between about 68 percent and 78 percent and having a viscosity in a 4 percent, by weight, solution in water of between about 1 and about 25 centipoises, and (b) a hydroxypropyl cellulose ether (HPC) having a molar substitution of between about 2 and about 4 hydroxypropoxyl groups per anhydroglucose monomer unit in the cellulose chain, with the HPC/PVA ratio, by weight, being between about 1/5 and about 2/1.
Dependencies are inferred from the claim text.