GB758125A - Apparatus for the continuous production of aminoplasts - Google Patents

Abstract

In apparatus for the continuous production of aminoplasts the liquid mixture of starting materials and condensation catalysts is continuously passed upwardly under pressure through a heated annular space between the walls of concentric cylinders over the rim of the inner cylinder and down a spiral channel on the innermost wall to a discharge duct leading to a surface cooler which stops the reaction. The reaction mixture 1 is fed through pipe 4 and filter 5 by pump 3 from tank 2 to regulator 6 which controls the flow into pressure reactor 8. Excess liquid from pump 3 is returned by pipe 11 to tank 2. The reaction mixture flows up space 15, heated by jacket 18 containing heaters 19, and over rim 16 to the spiral channel 25 on the inside wall of evaporator 14. A pressure of about four atmospheres is maintained <PICT:0758125/IV(a)/1> in reactor 8. Liquid condensate collects at the bottom of evaporator 14 and passes, via discharge valve 28, controlled by feelers 28b to ensure constant level, to cooler 32 where it is spread by roller 37 over the top of a stepped surface 33 down which it flows to outlet 38. The surface 33 is cooled from beneath by coolant 34. Vapours from reactor 8 pass to injector unit 41 which also draws vapours from cooler 32 and passes the mixed vapours to cooler 42 in which volatile constituents of the vapours are condensed by coolant 34 coming by pipe 36 from cooler 32. A central process control unit 46 governs the rate of throughput, the reaction time and the temperature and pressure. Reactor 8 is fitted with a safety valve, temperature and pressure indicators, inspection windows and internal lighting. The maximum temperature reached by the reactants in reactor 8 is preferably between 140 DEG and 150 DEG C. The reaction mixture is an aqueous solution of formaldehyde and urea, part of which may be replaced by thiourea and/or melamine. Condensation catalysts may be included, and thiourea is mentioned as a suitable catalyst.ALSO:<PICT:0758125/III/1> In apparatus for the continuous production of aminoplasts the liquid mixture of starting materials and condensation catalysts is continuously passed upwardly under pressure through a heated annular space between the walls of concentric cylinders over the rim of the inner cylinder and down a spiral channel on the innermost wall to a discharge duct leading to a surface cooler which stops the reaction. The reaction mixture 1 is fed through pipe 4 and filter 5 by pump 3 from tank 2 to regulator 6 which controls the flow into pressure reactor 8. Excess liquid from pump 3 is returned by pipe 11 to tank 2. The reaction mixture flows up space 15, heated by jacket 18 containing heaters 19, and over rim 16 to the spiral channel 25 on the inside wall of evaporator 14. A pressure of about four atmospheres is maintained in reactor 8. Liquid condensate collects at the bottom of evaporator 14 and passes, via discharge valve 28, controlled by feelers 28b to ensure constant level, to cooler 32, when it is spread by roller 37 over the top of a stepped surface 33 down which it flows to outlet 38. The surface 33 is cooled from beneath by coolant 34. Vapours from reactor 8 pass to injector unit 41 which also draws vapours from cooler 32 and passes the mixed vapours to cooler 42 in which volatile constituents of the vapours are condensed by coolant 34 coming by pipe 36 from cooler 32. A central process control unit 46 governs the rate of throughput, the reaction time and the temperature and pressure. Reactor 8 is fitted with a safety valve, temperature and pressure indicators, inspection windows and internal lighting. The maximum temperature reached by the reactants in reactor 8 is preferably between 140 and 150 DEG C. The reaction mixture is an aqueous solution of formaldehyde and urea, part of which may be replaced by thiourea and/or melamine. Condensation catalysts may be included, and thiourea is mentioned as a suitable catalyst.