What are foaming promoters and foaming catalysts?
In the modification of plastics, sometimes it is necessary to produce plastics with microporous structure, so foaming agents must be added. In order to expand the application scope of foaming agents in production, foaming promoters and foaming catalysts must also be added to accelerate the foaming reaction rate. This article introduces the difference between foaming promoters and foaming catalysts for readers.
Foaming promoter is a kind of compound that can reduce the decomposition temperature of foaming agent. In the foaming system, it is generally required that the decomposition temperature of the foaming agent should match the melting temperature of the resin. This undoubtedly limits the scope of use of blowing agents. In production, in order to expand the application range of the foaming agent, generally for solid resins, if the decomposition temperature of the foaming agent does not match the melting temperature of the resin, a foaming promoter can be added to reduce the decomposition temperature of the foaming agent.
Foaming catalyst is a kind of compound that can accelerate the reaction rate, effectively control the foaming process, and establish a good balance between the molecular chain growth reaction and foaming. It is usually mainly used in the foaming system of polyurethane (PU) and phenolic resin (PF).
There are many types of foaming promoters and foaming catalysts. Common foaming promoters mainly include the following types:
① Zinc compounds, such as zinc oxide, zinc octanoate, zinc nitrate and fatty acid zinc soap.
② Lead compounds, such as lead carbonate, lead phthalate, lead phosphite, tribasic lead sulfate, dibasic lead phosphite, lead phosphite, lead stearate and lead oxide.
③ Cadmium compounds, such as cadmium octanoate, cadmium hexanoate, cadmium laurate, fatty acid cadmium soap, etc.
④ Organic acids, such as stearic acid, lauric acid, salicylic acid, etc. ⑤ Urea and its derivatives, such as urea, ammonia, ethanolamine, etc.
Foaming catalysts are mainly amines, tin compounds and acids, and the commonly used varieties are mainly as follows:
① Amines mainly include aliphatic amines and alcohol amines, such as triethylenediamine, dimethyl Hexadecylamine, trimethylaniline, triethylenediamine, triethanolamine, ethanolamine, etc., which are mainly used in PU foaming system.
② Tin, mainly stannous octanoate, dibutyltin dilaurate, etc., is mainly used in PU foaming system.
③ Acids, mainly hydrochloric acid, sulfuric acid, phosphoric acid, benzenesulfonic acid, petroleum sulfonic acid, etc., are mainly used in PF foaming system.
