Hydroxypropyl methyl cellulose CAS NO.9004-65-3

Purpose: The monomer should be dispersed to stable granule in the polymerization process of PVC suspending polymerization system. By using HPMC as dispersant, it can effectively improve the suspendi…

Purpose: The monomer should be dispersed to stable granule in the polymerization process of PVC suspending polymerization system. By using HPMC as dispersant, it can effectively improve the suspending dispersing performance, the shape of granule, and the absorbency to plasticizing agent. Solution Preparation: In the production and use of PVC, normally the HPMC is confected to water solution for use. First, add 50% of needed deionized water (about 85οC); add in HPMC and stir for 45 minutes (80r/min-90r/min); then add in the rest of needed water; cool while stiring by cooling water for total soluble solution because HPMC swells by heat that delamination may happen in the solution if stir is not sufficient and quality of solution will be reduced. Different HPMC solution requires different cooling temperature: product 60HD50 to 20οC; product 65HD50 to 25οC. Application Hint: The amount of HPMC added has direct influence to the distribution of resin granule shape. Under the situation of no surface active agent and other salt, increasing the HPMC concentration will change the shape to fish eye, and high viscosity HPMC will cause rough granule. HPMC product polymerization system is very sensitive to soluble iron salt. Under centain circumstances, even rion content of <20ppm can cause rough granule; therefore, it is necessary to keep water, monomer and other materials pure from the pollution of iron.