Patent ID: 7041772

Claim:
A process for producing a benzoxazine resin comprising the steps of reacting a phenol compound, an aldehyde compound and a primary amine in the presence of an organic solvent to synthesize a benzoxazine resin and removing generated condensation water and the organic solvent from a reaction system under heating and a reduced pressure, wherein a pressure in the reaction system at the time of removal is set to 260 mmHg or higher, and wherein the pressure in the reaction system is set to less than 260 mmHg at the time that the temperature of a reaction mixture exceeds a minimal point and is higher than a temperature which is 10° C. lower than the softening point of the benzoxazine resin to be obtained, during removal of the produced condensation water and the organic solvent from the reaction system under a pressure of the reaction system being set to 260 mmHg or higher.