Patent GB-994890-A (GB)
Title: New organic polyisocyanates and their manufacture
Inventor: KERRIGAN VINCENT
IPC: C08G18/80
Filed: 1961-12-18
Abstract: The invention comprises allophanate polyisocyanates which are obtainable by reacting an excess of organic diisocyanate with a urethane isocyanate of formula R1(OOCNHRNCO)n where R1 is a monovalent or polyvalent organic radical, the residue of a mono or polyhydroxylic compound after reaction of the hydroxyl group with an isocyanate group, n is an integer from 1 to 6 and represents the functionality of the hydroxyl compound and R is a divalent organic radical, the excess of organic diisocyanate being an excess over that required for the reaction of one molecule of diisocyanat for each urethane group.  Examples of monoe hydric alcoholds from which R1 may bedrived include methanol, ethanol, isopropanol and phenol.ALSO:Allophanate polyisocyanates are produced by reacting an excess of organic diisocyanate with a urethane isocyanate of formula R1(OOCNHRNCO)n, wherein R1 is a monovalent or polyvalent organic radical, the residue of a mono- or poly-hydroxylic compound after reaction of the hydroxyl group with an isocyanate group, n is an integer from 1 to 6 and represents the functionality of the hydroxyl compound and R is a divalent substituted or unsubstituted organic radical, the excess of organic diisocyanate being an excess over that required for the reaction of one molecule of diisocyanate for each urethane group. The divalent radical R may be alkyl, cycloalkyl, aryl or aralkyl and may be substituted e.g. by halogen, nitro or other radicals non-reactive to the isocyanate group.  The radical R1 may preferably be derived from alcohols containing 2 to 6 hydroxyl groups, e.g. ethylene glycol, diethylene glycol, trimethylol propane, glycerol, butylene glycols and oxypropylation products of diethylene glycol, trimethylolpropane and sorbitol.  Any organic diisocyanate may be used, preferred diisocyanates are: hexamethylene-, tolylylene-, methylcohexyl-, and xylylene diisocyanates in an excess of from 10 to 300% over that required for the reaction of one molecule of diisocyanate with each urethane group.  A catalyst may be added, e.g. metal carboxylate, metal chelate, or tertiary amine. Many catalysts are listed. Without a catalyst the reaction is carried out at 100 DEG  to 160 DEG  C. and with a catalyst at 0 DEG  to 50 DEG  C. A solvent, e.g. ethyl acetate or butyl acetate may be used. The reaction product may be used as polyisocyanate in the production of polyurethanes which may be homogeneous or cellular, rigid or flexible.  In examples the reactants were:  (1) hexamethylene diisocyanate and diethylene glycol; (3) tolylene diisocyanate and trimethylol propane; (4) hexamethylene diisocyanate and oxypropylated sorbitol catalysed by pyrrolizidine; in (7) the product of Example (6) was reacted with an adduct of propylene oxide and triethanolamine to produce a polyurethane foam.ALSO:An allophanate polyisocyanate produced by reacting hexamethylene diisocyanate with oxypropylated sorbitol under conditions such that allophanate groups are formed by reaction of isocyanate and urethane groups in Example 5 (see Division C3) is subsequently dissolved (in Example 8) in ethylene glycol monoethyl ether acetate and dibutyltin dilaurate added and the solution painted on to clean tinned iron plates.