Heat Resistant Rigid Foams by Trimerization of Isocyanate Terminated Prepolymers

Abstract

Relative activities of a number of catalysts for isocyanate trimerization have been meas ured in order to select several having activi ties suitable for the preparation of rigid iso cyanurate foams. The effects of ring substitu ents on the rates of trimerization of phenyl isocyanate have been studied and attributed to a combination of steric and electronic fac tors. A series of rigid isocyanurate foams have been prepared by trimerization and simultaneous blowing of NCO terminated prepolymers. These foams retain dimensional stability and considerable strength up to 450°F., but degrade at about 480°F. Reac tions contributing to the degradation of these foams have been characterized by differ ential thermal analysis.

Reactive Flame Retardants for Polyurethane Foams

“…Various basic catalysts are used to control both the urethane and trimerization polymerization reactions. A number of investigators have exploited this chemistry in foaming by employing various TDI-terminated prepolymers as well as unrefined diisocyanatodiphenylmethanes (295)(296)(297)(298)(299)(300)(301)(302)(303)(304)(305)(306)(307)(308)(309)(310)(311)(312). Several have been recently developed into commercial products.…”

1,3,5-Tris(4-methoxyphenyl)-1,3,5-triazinane-2,4,6-trione

“…Trimerization of aromatic isocyanates, manufactured by cyclotrimerizing corresponding isocyanates, has been known to enhance the properties of polyurethanes or coating materials (Raders & Verkade, 2010;Duong et al, 2004;Tang et al, 1994;Zhitinkina et al, 1985;Nawata et al, 1975;Nicholas & Gmitter, 1965). Polymers, such as polyurethanes incorporated with isocyanurates, have enhanced thermal resistance, flame retardation, chemical resistance and filmforming characteristics.…”

“…For general background to trimerization of aromatic isocyanates, see: Raders & Verkade (2010); Duong et al (2004); Tang et al (1994); Zhitinkina et al (1985); Nawata et al (1975); Nicholas & Gmitter (1965).…”

Modified Isocyanurate Foams - Part I

“…Early reports by Nicholas and Gmitter (1) and Ball, et al (2) on preparation of isocyanurate foams disclosed that this new rigid cellular plastic displayed superior flame resistance properties in comparison to conventional and flame-retarded urethanes. These early foams also displayed a very high friability because of the highly crosslinked structure resulting from the trimerization reaction of isocyanate to isocyanurate.…”