The invention relates to the technical field of macromolecules, and discloses a preparation method of modified
polyurethane toughened
epoxy resin, which comprises the following steps: by taking 4-(Boc-amino)
phenylboronic acid, diethanol amine, 1, 3-bis (3-
glycidyl ether oxypropyl) tetramethyldisiloxane and the like as raw materials, carrying out a series of chemical reactions to obtain a borate
siloxane chain
extender; the method comprises the following steps: adding a
polyurethane prepolymer into the
epoxy resin, participating in chain extension of
polyurethane, and modifying the
epoxy resin by using the polyurethane
prepolymer to obtain the modified polyurethane toughened epoxy resin. A'
soft segment 'and an Si-O structure in the modified polyurethane can also improve the flexibility of a curing network, effectively change the fracture mechanism of the resin, absorb a large amount of energy when the resin is fractured, and contribute to improving the
toughness of the epoxy resin; on the basis of ensuring the strength of the epoxy resin, the
toughness and
flame retardant property of the epoxy resin are improved, and the epoxy resin can be applied to the fields of composite materials, coatings, adhesives and the like with higher
toughness and
flame retardant requirements, and has wide applicability.