Triazinic polyols

All the triazinic polyols discussed here, have a high thermostable triazinic structure and a high nitrogen content, which gives inherently flame retardant, rigid PU foams [24]. 

At this moment, in spite of their high application potential, the triazinic polyols are only used to a very small extent for rigid PU foam production. The structure of these triazinic polyols has many similarities to the structure of urethane - isocyanuric foams, the difference being that the triazinic rings (isocyanuric rings) are introduced into the PU structure with the polyol and in urethane-isocyanuric foams they are generated in situ (by trimerisation of -NCO groups). 

Aromatic polyols and triazinic polyols lead to polyurethanes with superior fire resistance due to the high char yield generated during the burning process. Sometimes, the rigid polyurethanes based on aromatic and triazinic polyols have an intrinsic flame retardancy (gives self-extinguishing foams without the addition of flame retardants). 

Flame retardant rigid PU foams, due to their high aromaticity, and high crosslink density are easier to be obtain. An aromatic polyol has a supplementary contribution to improving the fire resistance (for example Mannich polyols, novolak polyols, triazinic polyols based... 

As the polyol-based char formers needs to be substituted, Li and Xu40 reported the synthesis of a novel char former for intumescent system based on triazines and their derivatives. It is a macromo-lecular triazine derivative containing hydroxyethylamino, triazine rings and ethylenediamino groups (Figure 6.7). They showed that the new char former in an intumescent formulation containing APP... 

Modification of poly(carbodiimide) foams with polyols afford hybride foams containing urethane sections. However, the thermal stabilities of the poly (urethane carbodiimide) foams are lower. Using isocyanate trimerization catalysts, such as l,3,5-tris(3-dimethylaminopropyl)hexahydro-s-triazine, in combination with the phospholene oxide catalyst gives poly(isocyanurate carbodiimide) foams with improved high temperature properties. The cellular poly(carbodiimide) foams derived from PMDI incorporate six-membered ring structures in their network polymer structure. ... 

Modification of the poly(carbodiimide) foams, using polyols as comonomers, is possible, but the excellent thermal and flammability properties are reduced. Poly(carbodiimide isocyanurate) foams can also be continuously produced using 1,3,5-tris-(3-dimethylaminopropyl)-hexahydro-s-triazine as the cocatalyst. Other trimerization catalysts, such as potassium 2-ethylhexanoate and quaternary ammonium carboxylate (Dabco TMR 2) are also used as cocatalysts in the formation of poly(carbodiimide isocyanurate)... 

Higher alkylene oxylated derivatives of isocyanuric acid were claimed to be useful for poly(ester-imide) preparations [43], and also l,3,5-tris(2-hydroxye-thyl)-hexahydro-l,3,5-triazine-2,4-dione, prepared by reacting ethylene oxide and hexahydro-l,3,5-triazine-2,4-dione [44]. No wire enamels made from these polyols have been seen on the market. 

Similar polyols with triazinic structure are obtained by using cyanuric acid condensates. Cyanuric acid is a product of urea thermal decomposition or the product of hydrolysis of melamine or of cyanuryl chloride [40]. 

By the reaction of cyanuric acid with formaldehyde or by Mannich reaction with formaldehyde and diethanolamine interesting polyolic starters with heteroxyxlic triazinic structure are formed [31,41] ... 

By propoxylation of the resulting polyols (trimethylolisocyanurate and the Mannich base (15.44), in the presence of a tertiary amine as catalyst (for example dimethylaminoethanol) new heterocyclic polyols for rigid PU foams with a triazinic structure are obtained (reactions 15.45 and 15.46). 

---