PURPOSE: To contrive control of a uniform temperature, by a method wherein a storage tank, a gear pump and a mixing head are put in an oil tank whose temperature is controllable, each piping provided among them is formed by a platelike combination block and an openable and closable washing route is connected through a valve with a mixing head.

CONSTITUTION: A main agent tank 1 and a reactive liquid tank 2 being compounded are connected through a connecting block 3 and a control valve with a gear pump 5. The gear pump is connected through a connecting block 6 with a mixing head 7. They are put within an oil tank 11 of a predetermined temperature along with the respective valves. The mixing head is kept provided with three control valves 23 for the main agent, mixing of catalysts and a washing solvent, which are closed by either air or N2 pressure and opened by a spring. A route of a washing agent is connected through a connecting part 5 from a solvent tank 24 with the pouring port 26 of the mixing head.