Amide-modified isocyanurate foams

Amide-Modified Isocyanurate Foams. The amide linkage is a thermally stable, difunctional linkage. Amide-modified isocyanurate foams can be prepared by using carboxylic acids having at least two carboxylic groups as modifiers. 

Two-Step Process. A mixture composed of 100 g of 4,4 -diphenylmethane diisocyanate and 1.1 g of l-phenyl-3-methyl-l-phospholene oxide is stirred for 3 minutes at room temperature. After carbon dioxide is evolved 4.0 g of 2,4,6-tris(dimethylaminomethyl) phenol is added into the reaction mixture. The mixture generates a reaction exotherm and expands to form a foamed product. After curing at 125°C for one hour, the resultant foam is colorless and posesses low friability. 

One-Step Process. Into 100 g of polymeric isocyanate, 0.8 g of 1-phenyl-3-methyl-l-phospholine oxide, 2.1 g of methanol and 2.1 g of 2,4,6-tris(dimethylaminomethyl) phenol are mixed and stirred for 15 sec. After 10 sec of mixing, foam rise starts, and the rise time is 60 sec. Low-friable foamed products result. 

The co-use of furfuryl alcohol with a triazine derivative or triethanolamine and a quaternary borate ester-salt catalyzed the polymer- 

A modification of isocyanurate foams by incorporating urethane-, carbodiimide- and imide groups has been reported (97). An example is as follows. The amounts of ingredients used are shown in parts by weight in parenthesis. 

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Modification of cellular polymers by incorporating amide, imide, oxa2ohdinone, or carbodiimide groups has been attempted but only the urethane-modified isocyanurate foams are produced in the 1990s. PUIR foams often do not require added fire retardants to meet most regulatory requirements (34). A typical PUIR foam formulation is shown in Table 6. 

The modification linkages include urethane, amide, imide, carbodiimide and oxazolidone linkages. A urethane-modified isocyanurate foam (trade name Airlite Foam SNB, Nisshinbo, Ind. Inc.) was first applied to the petrochemical industry as a seamless fire-resistant insulant in 1965 (39). 

As opposed to flexible urethane foams, rigid urethane foams have a highly cross-linked chemical structure and a high percent of closed cells, e.g., over 90%. Rigid urethane foams can be classified as follows unmodified (or pure) rigid urethane foams and modified rigid urethane foams, which include isocyanurate-modified, epoxy-modified, amide-modified and oxazolidone-modified rigid urethane foams. 

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