Synthesis And Characterization Of Vinyl Chloride Copolymer With Enhanced Adhesive Property

Adhesive vinyl chloride copolymer resins were widely used in coating, print ink, magnetic tap bond and so on. To improve the adhesive property of vinyl chloride-with isobutyl vinyl ether(VC-IBVE) copolymer, 2-hydroxyethyl methacrylate (HEMA) was added to terpolymerizate. On the ground of the research on the emulsion stability, polymerization kinetics, composition control of VC-HEMA and VC-IBVE-HEMA emulsion polymerization system, VC-HEMA copolymer and VC-IBVE-HEMA terpolymer with more uniform composition distribution were synthesized, and the structure and property were studied .VC-HEMA copolymer and VC-IBVE-HEMA terpolymer was synthesized by emulsion polymerization, using K₂S₂O₈ (KPS) as initiator and sodium dodecyl sulfonate (SDS) as emulsifier. The latex became unstable as the feeding ratio of HEMA/H2O increased in both VC-HEMA and VC-IBVE-HEMA emulsion copolymerization system. It was caused by aqueous polymerization of HEMA and the increase of the solubility of SDS in water with the increase of HEMA/H2O. Polymerization kinetics was investigated for VC-HEMA and VC-IBVE-HEMA emulsion copolymerization. The copolymerization rate decreased with increase of HEMA fraction in the feeding monomers. With the increase of temperature and initiator concentration, the polymerization rate of VC-IBVE-HEMA increased.The reactivity ratios of VC and HEMA in bulk copolymerization were obtained as rvc=0.0123 and r_HEMA=18.53. While the apparent reactivity ratios of VC and HEMA in emulsion copolymerization were obtained as r_vc=0.341 and r_hema=4.29. The apparent reactivity ratios of IBVE-HEMA was fit as r₂3=0.0281 and r₃2'= 132.0 by least square method in combination with the apparent reactivity ratios of both VC-IBVE and VC-HEMA system. The composition of VC-IBVE-HEMA terpolymer was fitted by using the apparent reactivity ratio parameters of VC-IBVE-HEMA. The calculated compositon of HEMA in terpolymer is near to the actual composition ofthe terpolymer with low conversion. For terpolymers with high conversion, the calculated one was higher than the actual one. The terpolymer with more uniform composition distribution could be prepared by semi-continuous emulsion terpolymerization during which VC and HEMA was added.The Tg difference among semi-continuous terpolymers with different conversion was narrower, and with the increase of HEMA in feed, Tg of the final terpolymer of semi-continuous terpolymerization increased. The result of cross cut test indicated that adhesive strength with Al plate of terpolymers prepared by semi-continuous copolymenzation was improved with the increase of HEMA component in resins.