Preparation method of polyurethane foam

A method for preparing a rigid polyurethane foam, comprising the following steps of:

• (1) simultaneously pumping a mixed solution prepared from a hydrogen peroxide, an organic acid, a catalyst, a stabilizer and a vegetable oil into a first microstructured reactor of a micro-channel modular reaction device for reacting to obtain a reaction solution containing epoxidized vegetable oil;
• wherein a molar ratio of double bonds in the vegetable oil to the hydrogen peroxide to the organic acid to the catalyst to the stabilizer is 1:(6 to 20):(6 to 20):(0.02 to 0.4):(0.006 to 0.2);
• (2) simultaneously pumping the reaction solution containing the epoxidized vegetable oil obtained from the step (1) and a compound of formula III below into a second microstructured reactor of the micro-channel modular reaction device for reacting to obtain a vegetable oil polyol;
• wherein a molar ratio of an epoxy group in the epoxidized vegetable oil to the compound of formula III is 1:(1.5 to 4.5) and wherein the produced vegetable oil polyol is having hydroxyl value of 291-312 MCI KOH/g and viscosity of 4,658-4,959 mPas
• and
• (3) reacting the vegetable oil polyol prepared from the step (2) with a foam stabilizer silicone oil AK-8803, a cyclohexylamine, a diphenylmethane diisocyanate and a foaming agent cyclopentane for foaming so as to prepare the rigid polyurethane foam,
• wherein in the step (3), a mass ratio of the vegetable oil polyol to the foam stabilizer silicone oil AK-8803, the cyclohexylamine, the diphenylmethane diisocyanate and the foaming agent cyclopentane is 100:1.0:0.8:100:1.0;
• and
• wherein the produced polyurethane foam is having impact strength of 0.069 kJ/m2.