The invention relates to an anti-scaling agent, which is used for preventing polymer kettle scale generated on the inner wall of a polymerization kettle from adhering to the kettle wall, for example, in the polymerization process of vinyl monomers.
When vinyl monomer is polymerized in the presence of dispersant, emulsifier and polymerization initiator, solid polymer called kettle scale often adheres to the inner surface of the polymerization reactor, that is, its inner wall, stirring blades, baffles and condensers.
Due to the influence of these kettle scales, the heat transfer efficiency will decrease and the yield of products will also decrease. Because the peeling kettle scale is mixed into the product, the product quality will be reduced. In addition, in order to remove the kettle scale, it takes manpower and time, which will inevitably reduce its production efficiency, and there are many unfavorable factors such as labor safety and health of operators.
In order to solve these problems, many methods have been proposed to prevent the formation of kettle scale or prevent the kettle scale from sticking to the polymerization kettle.
For example, there is a method that dyes, pigments, other polar organic compounds, inorganic acids and their salts and multivalent metal salts are coated on the inner wall of a polymerization kettle, or they are added to a water-soluble medium. However, these methods have various disadvantages, for example, it is difficult to maintain the durability of their effects and make various characteristics of products worse.
As a scheme of these improved methods, it is also proposed to coat the inner wall of polymerization kettle with polymer compounds containing functional groups that can prevent the formation of kettle scale.
In the past, phenolic compounds were used as polymerization terminators, so many anti-scaling schemes using phenolic compounds were also proposed.
For example, in Japanese Patent PublicationNo. Zhao55- 16004, it is reported that the initial condensate of phenol and aldehyde reacts with nitrophenol. 4080 173, and in Japanese patent publicationNo. Zhao 55-543 17, it is pointed out that phenolic compounds react with aromatic aldehydes. Propylene glycol alginate is reported in Japanese Patent PublicationNo. Zhao 55- 1026 10, a polymer containing nitrile groups is reported in Japanese Patent PublicationNo. Zhao 55-1209, and rosin is reported to be modified in Japanese Patent PublicationNo. Zhao 58-740 1. Japanese Patent PublicationNo. Zhao58-2040006 reports a method of coating drying oil or semi-drying oil on the inner wall of a polymerization kettle with phenolic compounds and aldehydes as required.