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Application Characteristics Of Hydroxypropyl Methyl Cellulose In PVC Industry

The role of hydroxypropyl methyl cellulose in the polymerization of VCM is in the VCM suspension polymerization. In order to avoid the aggregation of polymer particles between early and late polymer droplets, it is necessary to participate in the VCM suspension polymerization system for loose protectants. Under the condition of fixed agitation, the types, properties and dosage of loose agent are the key factors to control the properties of PVC particles. The commonly used loose system is the multicomponent PVA system and the two large composite loose system of HPMC + multiple PVA, and the domestic use of the latter is mostly at that time.

(1) hydroxypropyl methyl cellulose polymerization temperature: the polymerization temperature based on the choice of average molecular mass of PVC, loose agent on the molecular weight of no effect, but in order to guarantee the effect of glue agent on the loose loose aggregates, we need to keep the loose gel temperature is higher than the polymerization temperature.

(2) particle characteristics: particle diameter, shape, porosity and particle distribution as an important guideline for SPVC quality, which are related to agitator / reactor plan, polymerized water / oil ratio, loose system and end conversion rate of VCM.

(3) hydroxypropyl methyl cellulose mixing: the same as the loose system has a great impact on the quality of SPVC, because the end particle depends on the standard of VCM droplet in water, the speed of agitation is accelerated, and the drop standard is reduced. When the stirring speed is too large, droplets will attack coalescence.

(4) loose protection system: protection system protects VCM droplets at the early stage of reaction, avoids swallowing, and once the generated PVC is accumulated in VCM droplets, the loose system protection is controlled by the agglomeration of particles, and then the SPVC particles are finished. The loose system is divided into the main loose system and the auxiliary loosening system. The main high sapond PVA loose powder, hydroxypropyl methyl cellulose, they affect the full function of SPVC; some characteristics of assistant system for moving SPVC particles loose. In general, large reactors can do the least with the use of loose systems.

(5) the main loose system of hydroxypropyl methyl cellulose: they are water-soluble, stabilizing VCM droplets by reducing the interfacial tension between VCM and water. The loosening agent is necessary to be used below the gel temperature, and the viscosity of the main dispersant solution should not be too high. The aspirations of SPVC are spherical, with high porosity, narrow particle size distribution and high accumulation density. The high porosity and high accumulation density are antagonistic to each other, and the best balance can be achieved by controlling the loose system. In the SPVC industry, the main loose powder was PVA and hydroxypropyl methyl cellulose. Hydroxypropyl methyl cellulose (HPMC) has the advantages of low dosage, thermal stability and excellent plasticizing function of SPVC, although it is still widely used in spite of the high price.

(6) the loose system of hydroxypropyl methyl cellulose is used to assist the loose system: they are connected with the main loose system, which can advance the porosity and dispatch the particle distribution. Compared with the water solubility of the main loose powder, they are appropriate to the solubility of VCM. Generally, the dosage of main loose powder can be slightly reduced after participating in the adjuvant of loosening agent.

Hangzhou Hongbo New Materials Co., Ltd 

Contact Person : Mison WANG


Mobile: 86-15990171382


Hangzhou Hongbo New Materials Co.,Ltd