In the process of processing unsaturated polyester resins, volatile toxic styrene will cause great harm to the health of construction workers. At the same time, the emission of styrene into the air can also cause serious air pollution. Therefore, the functional authorities of many countries limit the allowable concentration of styrene in the air of production workshops. For example, in the United States, the allowable PEL value (permissible exPOsure level) is 50 ppm, while in Switzerland, the PEL value is 25 ppm, such a low content is not easy to achieve. Relying on strong ventilation is also very limited. At the same time, strong ventilation will also lead to the loss of styrene from the surface of the product and the volatilization of a large amount of styrene into the air. Therefore, to find a way to reduce the volatility of styrene, from the root, it is still necessary to complete this work in the resin production plant. This requires the development of low-styrene volatile (LSE) resins that do not pollute or pollute the air or unsaturated polyester resins that do not contain styrene monomer.
Reducing the content of volatile monomers has been the subject of development in the unsaturated polyester resin industry abroad in recent years. There are many methods currently used:
1. The method of adding low volatility inhibitors.
2. The unsaturated polyester resin formulation without styrene monomer uses divinyl, vinyl methylbenzene and α-methylstyrene to replace the vinyl monomer containing styrene monomer
3. The formula of unsaturated polyester resin with low styrene monomer is to use the above monomer and styrene monomer together, such as the use of high boiling point vinyl monomer and styrene monomer such as diallyl phthalate, acrylic copolymer, etc. Use it
4. Another method to reduce the volatility of styrene is to introduce other units such as dicyclopentadiene and its derivatives into the skeleton of the unsaturated polyester resin to achieve low viscosity and ultimately reduce the styrene monomer content. Compared with the unsaturated resin of Kebao Chemical, the content of styrene meets the national standards.
In seeking to solve the problem of styrene volatilization, it is necessary to comprehensively consider the applicability of the resin to the existing molding methods such as surface spraying, lamination process, SMC molding process, the cost of raw materials for industrial production, and the compatibility with the resin system , Reactivity of resin, viscosity, mechanical properties of resin after molding, etc. In our country, there is no clear legislation on restricting the emission of styrene, but with the improvement of people’s living standards, people’s awareness of their own health and environmental protection, for the unsaturated consumer countries like us, the relevant legislation is only a matter of time