Preparation of antifoaming agent for PVC PVC foam board
1 preparation of antifoaming agent in PVC application of dispersants
PVC foamed sheet production phase is mainly distributed in the study of, when made with HPMC, PVA suspension must be prepared, and prepared to stir, so solution foam. Responsible for the loss of foam spills and dispersants, or height of the observation level, use DMCC MP319 defoamer on the Elimination of bubbles
2 application of defoamer in polymerization process
In the polymerization reaction, due to polymerization reaction system of HPMC, PVA is used as a dispersing agent, dispersing agent have a certain surface tension. As polymerization kettle in the mix may create bubbles, these may be called "wet bulb". "Wet bulb" above the liquid surface in the reaction system, resulting in gas phase polymerization of VCM, above the level of vessel wall viscosity in the pot, sticking off to the pot, resin-Black-Yellow point increase, affecting the quality of resin products. In the cauldron of the reflux condenser, in order to increase the cooling effect, responses have large amounts of VCM with gas crossing the liquid layer in the middle and to the condenser, condenser of condensing into a liquid, returned to the system. VCM with gas volatile in this process, produces large amounts of bubbles. This process takes place in the intense period of reaction, these bubbles can be called "dry bubble". Produced in the reaction system of "dry bulb" and "wet bulb" defoaming agent is needed to eliminate. Because of suspension reaction is an unstable system, anti-foaming agent variety selection are reasonable, will have a larger impact on the entire process. In addition, anti-foaming agents join methods should also be seriously considered, should start in response after 2 h, beginning with continuous drip and added, and defoaming agents should be suitably diluted, because of high concentrations of defoaming agent into the reaction system, has the potential to local failure of suspension system in reactor, coarse material particle, effect of resin quality
3 application of defoaming agent at the time of discharge
After the end of the polymerization, slurry flows into the worst response, no reaction of the VCM is to discharge. When unreacted gas discharge, discharging slot will have a lot of bubbles, bubbles with unreacted gas discharge, often cause pipe plug, material waste, and many other questions, use the defoamer can eliminate these. This process using defoamer, generic manufacturers and terminator and join. Select of Xiao bubble agent should has more wide of pH value applies range, and good of Xiao bubble performance and best of anti bubble performance, because for most of SMEs, recovery VCM monomer not used steam to Tower recovery, and in recovery VCM monomer process in the is no longer joined Xiao bubble agent, and recovery process needs is a time, so Xiao bubble agent anti bubble performance of bad directly effect to recovery VCM monomer of speed and time.
4 foam agent application in stripper action
Stripper VCM monomer recovery enterprises, removal of slurry when VCM by stripping the reaction ends, as are generally made in the stripper, paste to go from the top end of the Tower, and paste the steam by the end of the Tower up to full heat exchange, in this process, the slurry will produce bubbles on each tray. These bubbles can seriously impede slurry VCM volatile, increase the power of removal of VCM, remained on the Tower wall of bubbles for a long time will have a "black and yellow particles", affecting the quality of the product. In order to eliminate the stripping operation bubble, you need to use anti-foaming agent. Defoaming agent shall make appropriate dilution, uniform and stripping equipment, because the high concentration of defoaming agent, and may cause excessive absorption of PVC particles affect VCM monomer recovery and final treatment.