▎ 摘　　要

NOVELTY - Emulsified asphalt modifier comprises 4wt.% to 20wt.% polyurethane A component, 5wt.% to 25wt.% polyurethane B component, 0.15wt.% to 0.4wt.% initiator, 0.4wt.% to 4wt.% chain extenders, 0.02wt.% to 0.2wt.% nitrogen-doped graphene, 0.3wt.% to 1.5wt.% neutralizer, 10wt.% to 20wt.% diluent and deionized water. The polyurethane A component comprises methyl toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate or dicyclohexylmethane diisocyanate. USE - Emulsified asphalt modifier used in road building. ADVANTAGE - Emulsified asphalt modifier has integrated physical and chemical performance of graphene and polyurethane, and significantly enhances the road performance of emulsified asphalt. DETAILED DESCRIPTION - Emulsified asphalt modifier comprises 4wt.% to 20wt.% polyurethane A component, 5wt.% to 25wt.% polyurethane B component, 0.15wt.% to 0.4wt.% initiator, 0.4wt.% to 4wt.% chain extenders, 0.02wt.% to 0.2wt.% nitrogen-doped graphene, 0.3wt.% to 1.5wt.% neutralizer, 10wt.% to 20wt.% diluent and deionized water. The polyurethane A component comprises methyl toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate or dicyclohexylmethane diisocyanate. The polyurethane B component comprises polyethylene glycol, polypropylene glycol, polyoxypropylene glycol, polytetrahydrofuran diol, polyhexamethylene adipate, aminopropyltriethoxysilane or propylene glycol block polyether. The initiator is azobisisobutyronitrile or dibutyltin dilaurate. The chain extender is ethylenediamine, methyldiethanolamine, diethylenetriamine, 4,4'-diamino-3,3'-dichlorodiphenylmethane, aminoethylaminopropylpolydimethylsiloxane, ethylenediamine ethanesulfonic acid, dimethylolpropionic acid, dihydroxy half ester or dicarbamic acid. The neutralizing agent is formic acid, acetic acid, oxalic acid, hydrochloric acid, ammonia, trimethylamine, triethyl or triethanolamine. The diluent is acetone, butanone, methyl ethyl ketone, dioxane, N, N-dimethylformamide or N-methylpyrrolidone. An INDEPENDENT CLAIM is included for a method for preparing emulsified asphalt modifier, which involves: (A) weighing raw materials, which are polyurethane A component, polyurethane B component, initiator and the diluent and adding to the reaction vessel; (B) stirring and mixing to heat up to 70-90 degrees C for prepolymerization reaction for 1-2h; (C) adding nitrogen-doped graphene to the mixed liquid and then raising the temperature to 100 to 120 degrees C to carry out polymerization reaction for 1 to 3 hours; (D) cooling the mixed solution to 60 to 80 degrees C; (E) adding chain extender; (F) stirring for 3 to 5 hours, and then lowering to room temperature; (G) adding neutralizing agent and stirring for 0.5 h to obtain graphene/polyurethane compound, which is hydrophilic; (H) adding deionized water to the mixed solution under stirring; and (I) stirring is continued until a homogeneous emulsion is formed, followed by steaming the diluent to obtain a emulsified asphalt modifier.