GB981135A - Improvements in the manufacture of cellular polyurethanes - Google Patents

Abstract

Foamed polyurethanes may be prepared by reacting an organic polyisocyanate and a polyether containing at least two ether groups and two hydroxy groups per molecule, under such conditions that a foam forming gas is generated, and having in the reaction mixture an N-substituted dialkanolamine in an amount of at least 15% by weight of the polyether. The preferred polyethers are polymers and copolymers of ethylene oxide or propylene oxide, optionally prepared by polymerization in the presence of a substance having two or more active hydrogen atoms per molecule, such as ammonia and polydroxy compounds such as glycerol, triethanolamine and polyamines such as ethylene diamine and tolylene diamine. Other alkylene oxides may be used such as 1:2 butylene oxide and 2:3 butylene oxide. Many aliphatic and aromatic diisocyanates are listed as suitable polyisocyanates such as hexamethylene diisocyanate and tolylene 2:4-diisocyanate. Triisocyanate may also be used such as 2:4:6-triisocyanateotoluene. The foam forming gas may be generated by adding water to the reaction mixture to react with a proportion of the diisocyanate to produce carbon dioxide, or by incorporating a low boiling liquid having a boiling point not exceeding 75 DEG C. which will volatilize on heating. A combination of these two methods may be employed. Preferred low boiling liquids are halogenated alkanes containing fluorine, such as monofluorotrichloromethane, dibromodifluoromethane, 1:1:1 - trichloro - 2:2:2 - trifluoroethane, dichlorodifluoromethane, dichloromonofluoromethane, dichlorotetrafluoroethane, monochlorodifluoromethane, trifluoroethylbromide and mixtures thereof. Examples of suitable N-substituted dialkanolamines include N - methyl diethanolamine, N - ethyldiethanolamine, N-butyl diethanolamine, N-phenyldiethanolamine and N-methyl diisopropanolamine. Other additives which may be included are catalysts such as tertiary amines and soluble organic compounds of heavy metals such as iron and manganese acetyl acetonate, lead actoate, dibutyl tin dilaurate and stannous octoate, surface active agents, e.g. oxethylated phenols, oleyl alcohol, sulphated methyl oleate, polyalkyl or polaryl siloxanes and siloxane-oxyalkylene copolymers, flame retardants such as b -trichloroethylphosphate and dioctylphthalate, colouring matters and fillers such as carbon black and silica and colour stabilizers, whitening agents, and anti-oxidants such as tert-butylalcohol and sterically hindered phenols.