Patent GB-870273-A (GB)
Title: Improvements in process of trimerizing isocyanates
Filed: 1958-01-30
Abstract: Insoluble cross-linked polymers are prepared from di-isocyanate modified polyesters having aryl isocyanate groups at each end and formed by the action of excess of an aromatic diisocyanate with a polyester having terminal hydroxyl groups, by trimerizing the aryl isocyanato end groups at a temperature not exceeding 50 DEG C. in the presence of both a tertiary organic amine containing no groups reactive with the isocyanate under the reaction conditions, and an alkylene oxide of the general formula: <FORM:0870273/IV (a)/1> in which each of R1, R2, R3 and R4 is hydrogen or a hydrocarbon radical, the aromatic di-isocyanate being free from substituent groups which are reactive with the isocyanate group, the alkylene oxide or the amine.  The reaction may be effected in solution.  The amine and alkylene oxide catalysts may be used in amounts of from 0,1 to 2 moles or more per 100 moles of isocyanate.  Specified catalysts are ethylene, propylene and butylene oxides, triethylamine, tripropylamine, N : N1-dimethyl piperazine, N-methyl morpholine, diethyl cyclohexylamine, tetra methyl ethylene diamine, penta methyl diethylene triamine and di-(b -diethylamino ethyl) adipate.  In Example 6: a polyester (M.W. 2000) derived from adipic acid and a mixture of ethylene and propylene glycols is modified at both terminal hydroxy-end groups by reaction with toluene di-isocyanate and then trimerized with the aid of propylene oxide and triethyl amine.  Specification 773,569 is referred to.ALSO:Trimers of aromatic isocyanates are prepared by trimerizing at a temperature not exceeding 50 DEG C. an aromatic isocyanate RNCO in the presence of an alkylene oxide of the general formula:  <FORM:0870273/IV (b)/1> in which each of R1, R2, R3 and R4 represent hydrogen or a hydrocarbon radical, and a tertiary organic amine containing no groups reactive with the isocyanate under the reaction conditions, the aromatic radical R of the isocyanate comprising no substituent groups which are reactive with the isocyanate group, the alkylene oxide or the amine.  The alkylene oxide and amine catalysts may be used in amounts of from 0,1 to 2 moles or more per 100 moles of isocyanate. Specified catalysts are ethylene, propylene and butylene oxides and triethylamine, tripropylamine, N:N1-dimethyl piperazine, N-methyl morpholine, diethyl cyclohexylamine, tetramethyl ethylene diamine, penta methyl diethylene triamine and di-(b -diethylamino ethyl) adipate.  Reaction may be effected in the presence of a substantially inert solvent for the reaction mixture.  The isocyanates may be phenyl, naphthyl or anthryl compounds.  A preferred class is urethano substituted aryl isocyanates prepared by reacting one mole of an aromatic di-isocyanate with about a molar proportion of a saturated aliphatic alcohol; these yield on trimerisation tri (urethano aryl) isocyanurates which on heating at a temperature sufficiently high to decompose the urethano groups are converted to tri-(isocyanato-aryl) isocyanurates Examples describe the trimerization of phenyl isocyanate, p-tolyl isocyanate and a urethano isocyanate obtained by reacting n-butanol with 2:4-toluene di isocyanate; the trimerised urethano tolyl isocyanate is heated at 180-200 DEG C. with loss of butanol to give a tri-(isocyanato tolyl) isocyanurate.  Aromatic di-isocyanate modified polyester resins are also specified as suitable aromatic isocyanates (see Group IV(a)).  Comparative tests describe attempted trimerizations of phenyl iso cyanate with N-methyl morpholine or triethylamine only, yielding dimer and with propylene oxide only, yielding diphenyl urea.  Specification 773,569 is referred to.