A method for the preparation of stable and hard polyurethane - foams based on poly ether

摘要

PICT:0973121/C3/1 A stable rigid polyether-based polyurethane foam is formed upon a solid surface by spraying: (a) a polyoxyalkylene addition product of a polydydric alcohol having from 2 to 6 hydroxyl groups, a molecular weight 270-1,200, and an equivalent weight 90-300; (b) a tetra-(hydroxyalkyl) alkylene diamine having a molecular weight 220-400 and an equivalent weight 55-100; (c) an organic polyisocyanate; (d) a wetting agent; (e) a blowing agent solvent; and (f) a catalyst selected from triethylene diamine, dibutyl tin diacetate, dibutyl tin dilaurate, dibutyl tin di-2-ethyl hexoate, stannous octoate, stannous oleate, and mixtures thereof; and impinging the spray as an intimate mixture on to the surface while maintaining the following conditions:-(1) over-all NCO/OH equivalent ratio 0.8/1 to 1.2/1; (2) ratio of equivalents of (b) to (a) 0.75/1 to 6/1; (3) average equivalent weight of (a) and (b) combined 80 to 130; and (4) separation of components (b) and (c) until spraying. Spraying may be "one-shot", where all constituents are sprayed through a multiple orifice nozle or introduced through the mixing chamber of a single orifice nozzle; "pre-mix", where the spray is two component but the polyisocyanate is separated from the glycol or polyol until spraying; "pre-polymer", where at least part of the glycol or polyol is reacted with excess polyisocyanate by stirring at 50-130 DEG C. before spraying. The glycol or polyol may be the polyoxyethylene, polyoxypropylene, polyoxybutylene, or polyoxyethyleneoxypropylene derivatives of trimethylolpropane, glycerine, hexane triol, pentaerythritol, sorbitol, dimethylol phenols, triisopropanolamine, or tetra (2-hydroxy propyl) ethylene diamine. Polyoxypropylene glycols may be used and a number of suitable reactants are listed. Diamines may be ethylene, propylene, or butylene oxide addition products of ethylene, propylene, butylene, or amylene diamine of which a number are exemplified. A large number of suitable polyisocyanates are listed, and the wetting agent may be polyethylene glycol ethers of long chain alcohols, tert-amine or alkylolamine salts of long chain alkyl acid sulphate esters, alkyl sulphonic esters, and alkyl aryl sulphonic acids, or preferably the non-ionic surfactant prepared by sequential addition of propylene oxide and ethylene oxide to propylene glycol in amount 0.05-2.0%. The blowing solvent in amount 3-50% may be an alkane or halogenated alkane such as fluorotrichloromethane, but a number are listed including blends in which CO2 or N2 may be dissolved or dispersed. 0.1-2% of a listed antioxidant, and exemplified fillers and flame retardants may be included. As shown a prepolymer (Example 1) of a mixture of 2:4- and 2:6-tolylene diisocyanate and the polyoxypropylene derivative of trimethylol propane of average molecular weight 418 and also containing a liquid silicone surfactant is fed by compressed air entering at 14 from pressure pot 10 through hot-water heat-exchanger 26 and line 34, packed in trace lines 42 enclosed in jacket 44, to nozzle 36 of spray gun 40, also fed with compressed air through 45. Pressure pot 11 contains a mixture of N:N:N1:N1-tetrakis (2-hydroxypropyl) ethylene diamine, trichlorofluoromethane, triethylene diamine, and a barium-cadmium organic complex antioxidant which is passed to nozzle 37. The resulting spray may be applied to metal, e.g. Al, Cu, or steel, glass, wood, cement or paper board, and may be used for coating buildings, and lining or coating tanks, valves, or pipes. The examples refer to other combinations of constituents of the spray to make up the two components supplied to the two nozzles, and the foam may be conditioned for 1 week at 75 DEG F. and 50% humidity. Specifications 892,137 and 942,387 are referred to.ALSO:Polymethane foam forming reactants are sprayed on to a solid surface which may be metal, e.g. Al, Cu or steel, glass, wood, cement or paper board, and may be used for coating buildings, tanks, valves or pipes. The reactants are (a) a polyoxyalkylene addition product of a polyhydric alcohol having 2-6 hydroxyl groups, a molecular weight 270-1200 and an equivalent weight 90-300, (b) a tetra(hydroxyalkyl)alkylene diamine of molecular weight 220 -400 and an equivalent weight of 55-100, (c) an organic polyisocyanate, (d) a wetting agent, (e) a blowing agent solvent, and (f) a catalyst, and the spray impinges on the surface as an intimate mixture. Components (b) and (c) are separated until the spraying which may be "one-shot" where all the constituents are sprayed through a multiple orifice nozzle or introduced through the mixing chamber of a single orifice nozzle; "pre-mix", where the spray is two component but the polyisocyanate is separated from the glycol or polyol until spraying, "prepolymer" where at least part of the glycol or polyol is reacted with excess polyisocyanate before spraying. Fillers, e.g. carbon black, MgCo3, CaCO3 ammonium phosphate are mentioned. Many polymethane forming reactants are specified (see Division C3). Specifications 892,137 and 942,387 are referred to.