ABSTRACT
This paper describes a newly developed catalyst system based on metal and tertiary amine by fundamental investigation in CASE, especially sealant application. In CASE application, the most important point is to get the special step reaction profile: “Long pot life and with sharp increase in viscosity”.
In the CASE application, amine catalysts are very seldom used because they exhibit a short pot life with a mild viscosity rise. In these applications, mercury, lead or stannous catalysts are used mostly because they are strong gelling catalysts and exhibit long pot life with a sharp viscosity rise profile. However, some of these heavy metal catalysts show high toxicity. Tin catalysts exhibit a lower toxicity compared to the mercury or lead catalysts, however, they may contain endocrine disrupters such as tributyltin compound [1]. Nowadays, people even become more sensitive to the toxicity of chemical substances as well as the effects to the environment. Of course CASE producers or suppliers want to avoid the use of these toxic substances and look for alternative, however, no catalysts exhibited the requested viscosity rise profile.
Tosoh Corporation has examined the effectiveness of various metals and tertiary amine catalysts in several problems associated to the sealant application. We will propose a novel catalyst system, which is based on an amine catalyst. This system is non toxic while maintaining a long pot life with a sharp viscosity rise, as well as, excellent elastomer properties. These novel catalyst systems could also be applied in other CASE applications.
