GB887288A - Improvements in or relating to the manufacture of polyurethanes - Google Patents

Abstract

A process for the manufacture of elastomeric materials by reacting hydroxyl group-containing polymers containing at least two hydroxyl groups per molecule, such as polyesters, polyesteramides and polyethers, with organic polyisocyanates, is characterized in that the reaction is carried out in the presence of a tin compound of the formula R1R11SnX1X11 wherein R1 and R11 are alkyl groups which may be the same or different and X1 and X11 are organic acid radicals which may be the same or different. Specified tin compounds are those containing such alkyl groups as n-propyl, n-butyl, n-octyl or cyclohexyl and as acid radicals acetate, laurate, naphthenate, phenate, 2-ethyl hexoate or maleate. They are usually employed in about 0,01 to 5% by weight based on the weight of the polymer. The polymer usually has a hydroxyl value between 20 and 250. Glycols, dicarboxylic acids, hydroxy acids and amino compounds from which the polymers can be prepared are listed. Branching components such as glycerol, hexanetriols, triethanolamine, pentarythritol, trimesic acid, polymethacrylic acid, diethanolamine and dihydroxystearic acid are among the reactants specified. The polyethers can be those prepared from cyclic oxides in the presence of initiators such as water, diethylene glycol, hexanetriols, glycerol, triethanolamine, ethylene diamine, ethanolamine, sucrose or sorbitol. Particularly preferred are polymers containing predominantly secondary hydroxyl end-groups, such as polyesters and polyesteramides prepared from components including 1;2-propylene glycol, 1;3-butylene glycol, 2;3-butylene glycol and glycerol, and especially polymers obtained by polymerizing propylene oxide in the presence of, for example, hexanetriols, triethanolamine, glycerol, hexamethylene diamine, sorbitol, castor oil and castor oil derivatives. Preferred reactants for the polyurethane include at least one compound with more than 2 isocycanate or isocyanate-reactive groups per molecule. Pigments, fillers, plasticizers, antioxidants, stabilizers such as tert.-butyl catechol. In Examples (1) a linear polypropylene glycol and tolylene -2:4- and 2:6-diisocyanates are heated in the presence of dibutyl tin dilaurate. After cooling a glycerol/propylene oxide product is added and the mixture poured into a mould and cured by heating; (2) a hexanetriol/propylene oxide product is added to the initial reaction product in a similar process to (1). Uses. Printers rollers, potting and encapuslating compositions, and shock absorbers.