METHOD OF PREPARING PLASTICIZER FOR POLYVINYLCHLORIDE COMPOSITIONS Russian patent published in 1999 - IPC

FIELD: industrial organic synthesis. SUBSTANCE: method includes continuous isobutylene-formaldehyde condensation process, separation of hydrocarbon layer and returning light hydrocarbons into process, and separation of remaining reaction mass to distill 4,4-dimethyl-1,3-dioxan at 140-150 C/10-30 mm Hg. Remaining high-boiling by-products are rectified at still temperature 155-160 C and pressure 10-30 mm Hg. Light rectification fraction is utilized in condensation stage and still residue is used as plasticizer. Method is distinguished by that, amount of light rectification fraction fed into condensation zone is 4 to 10% of the total isobutylene-formaldehyde weight and the rest of this fraction is brought into interaction with formaldehyde at weight ratio (4-4.5):1 carried out in presence of acid catalyst in benzene until separation of water is finished. Purified and dried hydrocarbon layer of reaction mass is fed into another rectification column operated at still temperature 155-160 C at pressure 10-30 mm Hg. Bottom residue in this column is also used as plasticizer. Use of this product increases by 30% film rigidity and makes it more transparent. EFFECT: increased yield of plasticizer and improved its properties. 1 dwg, 1 tbl, 5 ex