▎ 摘　　要

NOVELTY - Preparing a graphene-modified aqueous polyurethane coating involves: (1) synthesizing a powder catalyst; (2) synthesizing a light stabilizer; (3) preparing a carboxylated graphene sheet; (4) putting powder catalyst obtained in the step (1), polytetrahydrofuran ether glycol and isophorone diisocyanate into a 500 ml four-neck flask, reacting at 70 degrees C for 1 hour, adding 0.2 g 2-sulfobenzoic anhydride and 0.05 g carboxylated graphene sheet obtained in the step (3), and reacting at 80 degrees C for 2 hours to obtain a polyurethane prepolymer (A), where the molecular weight of polytetrahydrofuran ether glycol is 500; and (5) adding 1.2 g aminobenzenesulfonic acid and 20 g acetone to the prepolymer (A), reacting at 75 degrees C for 2 hours, adding 1 g 2,4,6-trihydroxybenzoic acid and 1.2 g light stabilizer obtained in the step (2), again reacting at 85 degrees C for 0.5 hour, adding 12 g triethylamine to carry out neutralization reaction for 30 minutes, adding 110 g water, stirring and emulsifying. USE - The method is useful for preparing a graphene-modified aqueous polyurethane coating, which is useful for coating a furniture or a metal appliance. ADVANTAGE - The method enables economical preparation of the graphene-modified aqueous polyurethane coating with excellent flame retardance and light resistance in an environmentally-friendly manner. DETAILED DESCRIPTION - Preparing a graphene-modified aqueous polyurethane coating involves: (1) synthesizing a powder catalyst by adding 2.2 g 3-hydroxy-7-methoxy-2-naphthoic acid, 4.1 g sodium carboxymethyl cellulose, 1.6 g titanium trichloride, 0.6 g magnesium ethoxide, 5.3 g zinc acetate, 4.5 g diethanolamine and 3.2 g N-bromosuccinimide to 30 ml methyl ethyl ketone and 2 ml p-toluenesulfonyl chloride, reacting at 90 degrees C for 3 hours, evaporating the most of solvents, cooling and filtering, washing the filter cake with hot potassium bicarbonate solution, again washing with water to neutral, drying, and recrystallizing with tetrahydrofuran mixed with methanol and acetone; (2) synthesizing a light stabilizer by stirring 3 g sodium sulfite, 0.9 g sodium metabisulfite, 3.5 g sodium tripolyphosphate, 6.2 g citric acid, 4.5 g tea polyphenol, and 1.3 g dibutylhydroxytoluene were at 60 degrees C for 1 hour, adding 4.2 g aluminum carbonate and 1.6 g aluminum stearate, again stirring at 70 degrees C for 2 hours, adding 2.5 g methyltriethoxysilane and 3.2 g dimethylformamide, and stirring at 80 degrees C for 3 hours; (3) preparing carboxylated graphene sheets by adding 0.05 g graphene to 400 ml concentrated sulfuric acid, 0.4 g 4-boric acid triphenylamine and 0.3 g 3,4,5-trifluorophenylboronic acid, condensing and refluxing the mixture in an ultrasonic cleaner at a temperature of 70 degrees C, an ultrasonic power of 500 W and an ultrasonic frequency of 100 kHz for 3 hours, ultrasonically processing, diluting with 450 ml deionized water, then carrying out suction filtration with a microporous membrane having a diameter of 0.2 mu m, washing repeatedly with deionized water until neutral, finally baking at 80 degrees C for 8 hours, and grinding to a fine powder, i.e. a carboxylated graphene sheet, where the graphene is a graphene sheet produced by a chemical vapor deposition method, and the graphene sheet has a length of 0.1-10 mu m, a width of 0.1-10 mu m, a thickness of 1-10 nm, a purity of 99.5 wt.%, and a specific surface area of 500-2600 m2/g; (4) putting 0.6 g powder catalyst obtained in the step (1), 80 g polytetrahydrofuran ether glycol and 40 g isophorone diisocyanate into a 500 ml four-neck flask provided with a stirring paddle, a thermometer and a condensation tube, reacting at 70 degrees C for 1 hour, adding 0.2 g 2-sulfobenzoic anhydride and 0.05 g carboxylated graphene sheet obtained in the step (3), and reacting at 80 degrees C for 2 hours to obtain a polyurethane prepolymer (A), where the molecular weight of polytetrahydrofuran ether glycol is 500; and (5) adding 1.2 g aminobenzenesulfonic acid and 20 g acetone to the prepolymer (A), reacting at 75 degrees C for 2 hours, adding 1 g 2,4,6-trihydroxybenzoic acid and 1.2 g light stabilizer obtained in the step (2), again reacting at 85 degrees C for 0.5 hour, adding 12 g triethylamine to carry out neutralization reaction for 30 minutes, adding 110 g water, stirring and emulsifying.