Trigonox® 21S Is an initiator for the (co-polymerization) of ethylene, styrene, acrylonitrile, acrylates and methacrylate. is a perester which is used for the curing of unsaturated polyester resin at elevated and high temperatures.

Trigonox 21S is preferred for the curing of UP resin based Hot Press Moulding formulation (such as SMC and BMC) in the temperature range of 120 - 160°C. As Trigonox 21S is a high reactive peroxide, it is very suitable as a kicker in formulations for pultrusion and SMC/BMC. In combination with a cobalt accelerator, Trigonox 21S is also applicable for the cure of UP resins in the temperature range of 60°C and higher.

Application area can be air drying lacquers, diplacquers, wall panels, filament winding, etc.

tert-Butyl peroxy-2-ethylhexanoate chemical formula

Storage Due to the relatively unstable nature of organic peroxides a loss of quality can be detected over a period of time. To minimize the loss of quality,AkzoNobel recommends a maximum storage temperature (Ts max.) for each organic peroxide product.

For Trigonox 21S Ts max.= 20°C and Ts min. = -30°C to prevent crystallization When stored according to these recommended storage conditions, Trigonox 21S will remain within the AkzoNobel specifications for a period of at least 3 months after delivery.

Thermal stability Organic peroxides are thermally unstable substances, which may undergo self-accelerating decomposition. The lowest temperature at which self- accelerating decomposition of a substance in the original packaging mayoccur is the Self-Accelerating Decomposition Temperature (SADT). The SADT is determined on the basis of the Heat Accumulation Storage Test.

For Trigonox 21S SADT : 35°C Emergency temperature (Tem) : 25°C Control temperature (Tc) : 20°C

The Heat Accumulation Storage Test is a recognized test method for the determination of the SADT of organic peroxides (see Recommendations on the Transport of Dangerous Goods, Manual of Tests and Criteria - United Nations, New York and Geneva).

Trigonox 21S is classified as Organic peroxide type C; liquid, temperature controlled, Division 5.2; UN 3113; PG II.

Safety and handling Keep containers tightly closed. Store and handle Trigonox 21S in a dry well-ventilated place away from sources of heat or ignition and direct sunlight. Never weigh out in the storage room.

Avoid contact with reducing agents (e.g. amines), acids, alkalis and heavy metal compounds (e.g. accelerators, driers and metal soaps). 

Dosage Depending on working conditions, the following dosage levels are recommended:

Trigonox 21S 1 - 2 phr *

Accelerator NL-49-P 0.5 - 3 phr