What are the raw materials of foam plastics and how do they come out?
The foaming agents for epoxy resins are two types: physical foaming agents and chemical foaming agents. Physical foaming agents are mainly low boiling liquid, such as three chloro methane (F11), three chlorine, three fluorine ethane (F112), two chlorine, two fluorine methane (F12) and so on. By using the curing heat of the epoxy resin, the liquid with low boiling point is evaporated, and the gas is released, and the products are small in density and low in thermal conductivity. But fluorine hydrocarbons have a damaging effect on the atmosphere and are often used to spray foaming processes. According to the experts of China epoxy resin industry association, toluene and so on can be used as auxiliary foaming agent. In addition to foaming, it also acts as a curing reaction, a heat absorber and a diluent.
More bisphenol A epoxy resin, epoxy value of 0.51 ~ 0.22mol/100g. When the viscosity is 25 degrees centigrade, it is 20Pa / S; the viscosity is 130 s at 1Pa.
Chemical blowing agents are mainly azo organic compounds such as azo two formamide (ADCA or AC), 2, 2 '- azo two, DAB, AIBN, etc.. This kind of foaming agent is cheap, and the products are non-toxic, odorless and colorless. In addition to sulfonylhydrazine, such as 4, 4 '- oxo benzene sulfonyl hydrazide (OBSH) etc.. Attention should be paid to the decomposition temperature. The properties of chemical foaming agents are as follows:Azo two formamide (AC, ADCA). Orange crystalline powder. A large amount of gas (N2, CO and a small amount of CO2) is decomposed at 120 DEG C, and the gas yield is 200 ~ 300mL/g in the standard state, which is an efficient foaming agent.
