| 摘要 |
Thermoplastic wood resins which are soluble in aromatic hydrocarbons but which are substantially insoluble in aliphatic hydrocarbons and which have an average softening point of about 185 DEG F. to about 250 DEG F., are obtained by solvent extraction from pine wood. The pine wood, preferably in shredded form, is treated with an aliphatic solvent such as petroleum ether, gasoline, heptane or hexane, to extract terpene and rosin-type materials and is then treated with an aromatic solvent such as benzene, toluene, naptha or xylene to extract the desired resins. The solvent is then evaporated or distilled off. An alternative method of obtaining the wood resins comprises subjecting the pine wood to extraction with aromatic hydrocarbon solvents to remove with the resin-type materials and the aliphatic hydrocarbon, insoluble materials. The solvent is then separated from the resinous materials. Pine oil, turpentine and other volatiles are removed from the resinous residue by distillation and the remainder is extracted with aliphatic solvents leaving the thermoplastic wood resins.ALSO:Oxyalkylation products are prepared by reacting an alkylene oxide having 2-4 carbon atoms with a thermoplastic wood resin obtained by solvent extraction of pine wood, said resin being soluble in aromatic hydrocarbons and substantially insoluble in aliphatic hydrocarbons. Suitable resins are those having an average softening point of about 185-250 DEG F., e.g., those having the Trade Marks "Vinsol," "Belro" and "Solo." The process may be carried out by dissolving the resin in the alkylene oxide and conducting the reaction in a pressure vessel, or by dissolving the resin in an inert solvent or in a conventional polyether polyol and then reacting the solution with the alkylene oxide. The products having a hydroxyl value of 50 to 500 are used in the manufacture of rigid and flexible polyurethane foams. In the preparation of rigid foams, it is preferred that the oxyalkylation products have a hydroxyl number of 200-500 while products of number 50-70 are useful for preparing flexible foams. The foams are prepared by reacting the oxyalkylation product, which may be blended with a polyether polyol conventionally used in polyurethane production, with an organic polyisocyanate in the presence of a catalyst, a blowing agent and an emulsifier. Amine compounds may also be present in the reaction mixture. The prepolymer method for the preparation of foams is also described in which a polyurethane resin is cured in the presence of a catalyst, suitably a tertiary or hydroxy amine or an organic salt of tin. To convert this to a foam, a gassing agent, preferably a halocarbon, is added. An emulsifier and/or surfactant may be present in the reaction mixture. |
