| 摘要 |
In a process for the preparation of a polyurethane from an organic polyisocyanate or polyisothiocyanate reactant and a polyether reactant, the polyether reactant comprises a polyol having an average molecular weight of at least 4,000 and formed by reacting (1) a condensation product of an alkylene oxide reactant and an organic compound having at least three active hydrogen atoms in the molecule with (2) at least 1% but less than 10% of ethylene oxide (by weight of the alkylene oxide content of the condensation product). "Alkylene oxide reactant" means any organic compound or compounds, except ethylene oxide, which contains in the molecule an epoxy group capable of reacting with the active hydrogen atoms of an organic compound having a plurality of active hydrogen atoms in the molecule to form a condensation product. Polyurethane foams can be prepared by the one shot or prepolymer methods. Prepolymers containing either free isocyanate or hydroxyl radicals can also be converted into polyurethane plastics. In preparing the polyols there can be used nucleating agents containing active hydrogen as part of hydroxyl, phenolic, carboxylic, mercaptan, thiophenol or thiocarboxylic groups. Examples are glycerol, pentaerythritol and sucrose. The condensation products reacted with the ethylene oxide can be random or block copolymers obtained from a plurality of alkylene oxides other than ethylene oxide. In preparing prepolymers up to 0.5% water can be present to give a "water-branched" prepolymer, The reaction can be effected in inert gas atmosphere. The propolymer can be converted to synthetic rubber by heating with inorganic or organic bases or to plastics by reaction with water, glycols, diamines, dicarboxylic acids, hydroxyamines, hydroxy acids or amino acids. Foams can be prepared by reacting the prepolymers with water, hydrogen sulphide, carboxylic acids, or esters or polyesters containing free carboxylic groups. A film of a solution of prepolymer in benzene, toluene, xylene, solvent naphtha, gasoline, carbontetrachloride ethyl acetate or amyl acetate can be exposed to atmospheric moisture or reacted with an organic compound containing active hydrogen atoms to give a polyurethane sheet. In examples the polyols are prepared (1) to (5) by reacting glycerol in the presence of potassium hydroxide with propylene oxide and reacting the product with different amounts of ethylene oxide. They are converted to foams by the one-shot method by reaction with tolylene diisocyanates, water, silicone fluid and mixtures of (1) triethylene diamine, dibutyl tin laurate and stannous octoate, (5) triethylamine, triethylene diamine and dibutyl tin laurate. Specification 868,996 is referred to.
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