GB769091A - Production of condensation products, resinous foams and polymeric materials of high molecular weight - Google Patents

Abstract

A polyurethane is made by reacting in the liquid state and under anhydrous conditions an organic isocyanate or isothiocyanate of the formula R(NCX)n, where R is an organic group, X is oxygen or sulphur and n is at least 2, with a polyalkylene glycol having a molecular weight of at least 200 in amount such that the ratio of -(NCX) groups to the OH groups contained therein is greater than 1 : 1. The reactants are merely mixed together, or where solid at room temperature they are melted before mixing. The reaction may also be effected in a solvent, e.g. benzene, toluene, xylene, naphtha, gasoline, carbon tetrachloride, ethyl acetate or amyl acetate, and may be accelerated by the addition of up to 5 per cent of sodium or potassium hydroxide or a tertiary amine, e.g. N-methylmorpholine, triethylamine, tripropylamine, tributylamine, pyridine or quinoline. Many isocyanates and isothiocyanates are specified. The polyalkylene glycols, e.g. tetraethylene glycerol, polyethylene glycols having average molecular weights of 200, 400 and 600, polypropylene glycols having average molecular weights of 400, 750, 1200 and 2000 and carbowaxes having average molecular weights of 500 to 600 and 1000, may be used alone or in conjunction with polyols, e.g. pentaerythritol, sorbitol, sucrose, glycerine, glycerine-ethylene oxide condensate and triethanolamine-ethylene oxide condensate, or with monomeric diols, e.g. ethylene-, propylene- or butylene-glycol, 2-methyl pentane diol, 2-ethylhexane diol, styrene glycol, glycol-a -isopropyl ether or glycerol-a -phenyl ether. Polyurethanes or mixtures of polyurethanes and isocyanates or isothiocyanates result respectively where the ratio (NCX : OH) falls short of or exceeds n : 1. The polyurethanes so produced contain iso- or isothio-cyanate groups and may be reacted further either per se or with water or other compounds containing a plurality of active hydrogen atoms, e.g. hydrogen sulphide, carboxylic acids or esters or polyesters thereof, preferably in the presence of an emulsifying agent, to yield resinous foams or bubblefree resins, and find use in the production of adhesives, coating compositions, electrical-, heat- and sound-insulation materials, plastic articles, laminated products, radomes, abrasive articles and internal coatings for metallic receptacles. In examples (1, 3, 6 to 11 and 17)-m-tolylene diisocyanate is reacted with polyethylene glycol (200 or 400) in the presence or absence of dry benzene and in the presence or absence of various polyols to give liquids which may be further reacted in the presence of a tertiary amine to yield tough films; (12 to 16) the same reactants as used to make polyurethanes which are reacted further with water and ethylene glycol in the presence of emulsifying agents and tertiary amines to yield foamed products; (2, 4, 5) the isocyanate used is p.p1-diisocyanatodiphenylmethane; (18 to 21) particular applications are described in detail. Films of the polyurethanes are made by applying a volatile solvent, e.g. acetone, to a non-adhesive surface such as mercury and then casting a film of the polyurethane upon the surface of the mercury, with subsequent evaporation of the solvent and gradual reaction with atmospheric moisture or other active hydrogen-containing compound. The hardened film may then be removed from the non-adhesive surface.ALSO:In example (18) samples of aluminium and cold rolled steel were cleaned and coated with a benzene solution of a polymethane (see Group IV(a)) and then allowed to dry at room temperature and then at elevated temperatures. Corrosion resistant sheet metal objects such as autobodies, airplanes and air-conditioning conduits may be coated with resinous foams by depositing the polyurethane on the surface of the selected base and exposing the coating to atmospheric moisture to cause foam formation of the polyurethane.