Study On The Preparation Of Carbomer By The Method Of Precipitation Polymerization

Carbomer resin has excellent thickening, gelling, adhering, emulsifying and suspending abilities. Because of these performances, it was recorded by the Pharmacopoeias of the United States, Britain and some other countries. It can also be found in2000Edition of the Pharmacopoeia of China. Carbomer resin has occupied an important position in the pharmaceutical and cosmetics industries. Due to the security of foreign synthetic technology, there are few papers and articles about the composition, synthetic method and details process of carbomer resin, while most of them are about thickening property. Domestic development of carbomer resin is still in its infancy, with few large-scale industrial production. Considering the increasingly-developed domestic cosmetics, pharmaceutical industries in which carbomer resin plays a significant roll, the total domestic need for carbomer resin is especially large. But there are few manufacturers in China, the carbomer resins are mostly imported from the United States, Japan and so on. It is of a great practical significance to study on the synthetic technology of carbomer resin.Comparing with the emulsion polymerization and suspension polymerization, which are currently used in the preparation of polymers, precipitation polymerization has a broader application. It is easy to control the pattern of the product and the heat transfer in suspension polymerization,but there are small amount of dispersant residues. When solid products are ncessary, emulsion polymerization requires filtering, washing and drying processes, which is complex. And it also leaves emulsifiers and other impurities in the products, which are difficult to exclude and effect the electrical performance. In solution polymerization, it is hard to stir in the middle and later stage of polymerization because of the high viscosity, the monomer concentration should be low because of the adverse thermal diffusion, and it’s difficult to increase the molecular weight because of the solvent effects. Precipitation polymerization can remain the advantages of solution polymerization, overcoming the large viscosity of polymerization system and contributing to increase the molecular weight, thereby improving some application properties of water soluble polymers. Mixing acrylic acid monomer and initiator with solvent of cyclohexane and ethyl acetate, after deoxidation and thermal initiation, we can get carbomer particles in the solution. Removing the solvents, carbomer powder is obtained. This is the simple and promising preparation process for carbomer preparation. We investigated the relations between the appearance and thickening ability, clarity performance and stability. Conclusions showed that we obtain a high performance of carbomer with the propotion of monomer10%,initiator0.2%(by the weight of monomer), dispersing agent0.4%(by the weight of monomer), cross-linking agent0.4%(by the weight of monomer), and we characterized its properties.