Abstract: For in mold spraying, a double-inclined mixing nozzle is connected obliquely and fixedly with a side surface of a third half-mold through a lateral sealing structure and connected with a side surface of a first half-mold in an inclined and sealing manner, side faces of a first half-mold and the third half-mold are respectively provided with installation inclined surfaces. A lateral sealing structure includes a mounting plate and a sealing member. The sealing member is sleeved on the double-inclined mixing nozzle and is in transition fit with the double-inclined mixing nozzle and the mounting plate respectively. A butt sealing groove provided on the installation inclined surface of the first half-mold and is in sealing fit with the mounting plate.