| 摘要 |
Polyurethanes are prepared by reacting an organic polyisocyanate with a polyhydroxy compound which is the reaction product of cyanuric acid and an alkylene oxide. Suitable alkylene oxides are ethylene oxide, 1,2-propylene oxide and 1,2-butylene oxide preferably in amounts to provide reaction products containing from 3 to 200 oxyalkylene units for each cyanuric acid residue. Conventional aliphatic, cycloaliphatic and aromatic diisocyanates may be used as well as triisocyanates, reaction products of an excess of a diisocyanate with a polyhydric alcohol, uretedione dimers and isocyanurate polymers of diisocyanates and polyisocyanate compositions obtained by the phosgenation of the mixed polyamine reaction products of formaldehyde and aromatic amines. Foamed polyurethanes may be prepared by incorporating water and/or a low boiling point liquid into the reaction mixture. Suitable low boiling point liquids are hydrocarbons and hydrogenated hydrocarbons having boiling points not exceeding 75 DEG C. Rigid foamed materials may be prepared by using as the polyhydroxy compound a mixture containing from 40 to 90% by weight of a reaction product of cyanuric acid and an alkylene oxide having an OH value of 400 to 600 mg.KOH/g. and from 60 to 10% by weight of another polyhydroxy compound having at least three isocyanate-reactive groups in the molecule and a combined hydroxyl and acid value of from 300 to 600 mg.KOH/g. The latter mentioned polyhydroxyl compounds may be conventional polyethers and polyesters. Catalysts such as tertiary amines and organic compounds of tin, iron, manganese and lead may also be included in the polyurethane-forming reaction mixture. The cyanuric acid may be reacted with an alkylene oxide preferably at temperatures between 100 DEG C. and 140 DEG C. in the presence of a basic catalyst and a solvent. Preferred catalysts are alkali metal hydroxides, calcium hydroxide, sodium carbonate, quaternary ammonium hydroxides and tertiary amines. Suitable solvents are N, N-dimethylformamide, dimethylsulphoxide, formamide and diethyl carbonate. Mixtures of alkylene oxides may be used or the cyanuric acid may be reacted with the alkylene oxides in more than one stage, a different oxide being used at each stage.ALSO:Oxyalkylation products of cyanuric acid may be prepared by reacting an alkylene oxide with cyanuric acid in the presence of a basic catalyst and a solvent for the cyanuric acid. In examples, cyanuric acid is reacted with 1,2 propylene oxide in N,N-dimethylformamide in the presence of (1) sodium hydroxide, and (2) N,N-dimethyl benzylamine as catalyst. |
