Patent GB-619275-A (GB)
Title: Manufacture of polymeric ureas
IPC: C08L75/02
Filed: 1946-11-29
Abstract: A polyamine and carbon dioxide are condensed at an elevated temperature, preferably between 100 DEG  and 350 DEG  C., and under a pressure exceeding 100 atmospheres to give polymeric ureas which may be spun into fibres or made into films.  The polyamines may, in some cases, be suspended or dissolved in a liquid such as benzene or phenol and meta-cresol.  The products, which have intrinsic viscosities between 0.4 and 0.8, may be represented by the general formula (NH.R.NH.CO)x, examples of the divalent organic radical R being -C3H6.O.C3H6-; -C3H6.O.CH2.O.C3H6-; -C2H4.NH.C2H4-; -C3H6.S.C3H6-; -CnH2n-; where n is any integer from 6 to 10 inclusive.  The polyamines used are generally aliphatic or cycloaliphatic compounds having at least two primary amine groups and the carbon chain may include substituent groups or be interrupted by other atoms or groups such as O, S and NH.  Preferred polyamines are diamines containing 6 to 14 carbon atoms and include hexamethylene diamine, decamethylene diamine, octamethylene diamine, g ,g 1-diaminopropyl ether, ethyleneglycol bis-g -aminopropyl ether, diethylenetriamine and g ,g 1-diaminopropyl sulphide.  The pressure used is generally 200 to 800 atmospheres, but may range up to 10,000 atmospheres and higher.  The polyamine may be converted into its carbonate, as by bubbling carbon dioxide through the melted polyamine, before condensation and the latter may be a batch or continuous process.  It is preferable to remove liberated water as by sweeping it out with dry carbon dioxide or by conducting the condensation in the presence of a liquid having an affinity for water but low solvent power for the product or by suspending a dehydrating agent such as phosphorus pentoxide in the vapour space.  In examples, carbon dioxide was reacted with (1) hexamethylenediamine at 200 DEG C. and 500 atmospheres for 22 hours; (2) hexamethylenediamine carbonate at 220 DEG  C. for 7 hours; (3) hexamethylenediamine carbonate at 200 DEG  C. and 500 atmospheres for 1 hour while bleeding off gas, the product ground and the reaction continued at 200 DEG  C. and 500 atmospheres for 13 hours; (4) g ,g 1-diaminopropyl ether carbonate was reacted at 220 DEG  C. and 2000 atmospheres for 7 hours with hourly release of pressure; (5) hexamethylenediamine dissolved in meta-cresol was reacted at 250 DEG C. and 500 atmospheres for 24 hours, the product being obtained by precipitating with alcohol.ALSO:Polyamine carbonates are prepared by bubbling carbon dioxide through the melted polyamine.  The polyamines are generally aliphatic or cycloaliphatic compounds having at least two primary amino groups and the carbon chain may include substituent groups or be interrupted by other atoms or groups such as O, S and NH. Preferred amines are diamines containing 6 to 14 carbon atoms and include hexamethylene diamine, decamethylene diamine, octamethylene diamine, g :g 1-diamino propyl ether, ethylene glycol bis-g -aminopropyl ether, diethylene triamine and g :g 1-diamino propyl sulphide.  The carbonates are starting materials in a preparation of polymeric ureas (see Group IV (a)).