▎ 摘　　要

NOVELTY - Chemically modifying aqueous wood coating by nanocellulose-dispersed graphene comprises e.g. subjecting cellulose raw material for extraction treatment and delignification treatment to obtain hemicelluloses, subjecting to mechanical pretreatment or chemical mechanical mixing pretreatment to obtain hemicellulose-containing nanofiber aqueous solution, where mechanical pretreatment specifically comprises adding deionized water in hemicellulose to make 0.1-0.3% hemicelluloses, treating with high pressure homogenizing machine at 600 bar for 30-40 minutes to obtain hemicellulose-containing nanocellulose aqueous dispersion, where amount of hemicellulose is 20-30% of the mass of the cellulose, the chemical mechanical mixing pretreatment comprises adding deionized water in 1-0.3% hemicelluloses, adding sodium bromide and TEMPO reagents, performing magnetic stirring, adding sodium hypochlorite at 2.5-3 ml/minute rate, adjusting pH to 10-10.5, and reacting until pH is stable. USE - The method is useful for chemically modifying aqueous wood coating by nanocellulose-dispersed graphene. ADVANTAGE - The method improves mechanical properties i.e. adhesion, abrasion resistance, hardness and impact resistance of the water-based wood coating, impart certain electrical conductivity, thermal conductivity and anti-UV resistance and aging resistance. DETAILED DESCRIPTION - Chemically modifying aqueous wood coating by nanocellulose-dispersed graphene comprises (i) subjecting cellulose raw material for extraction treatment and delignification treatment to obtain hemicelluloses, subjecting to mechanical pretreatment or chemical mechanical mixing pretreatment to obtain hemicellulose-containing nanofiber aqueous solution, where mechanical pretreatment specifically comprises adding deionized water in hemicellulose to make 0.1-0.3% hemicelluloses, treating with high pressure homogenizing machine at 600 bar for 30-40 minutes to obtain hemicellulose-containing nanocellulose aqueous dispersion, where amount of hemicellulose is 20-30% of the mass of the cellulose, the chemical mechanical mixing pretreatment comprises adding deionized water in 1-0.3% hemicelluloses, adding sodium bromide and TEMPO reagents, performing magnetic stirring, adding sodium hypochlorite at 2.5-3 ml/minute rate, adjusting pH to 10-10.5, reacting until pH is stable, where amount of sodium bromide is 12-13 wt.%, TEMPO reagent is 1-2 wt.% and sodium hypochlorite is 25-35 wt.%, performing suction filtration, washing by water, adding deionized water and sodium chlorite to adjust pH to 4-5, magnetically stirring at 70-80 degrees C for 1-2 hour, performing suction filtration, washing using water to obtain carboxylated cellulose, where the mass ratio of the deionized water to the hemicellulose is 95-105:3, the amount of sodium chlorite is 25-35 wt.%, preparing 0.1-0.3% aqueous carboxylated cellulose dispersion, mechanically dispersing by high-speed mixer at 14000-16000 revolutions/minute for 20-30 minutes to prepare hemicellulose-containing nanocellulose aqueous dispersion, where the amount of hemicellulose is 10-20 wt.%, (ii) placing graphene or the reduced graphene in hemicellulose-containing nanocellulose aqueous dispersion, mechanically dispersing under high-speed stirring conditions at 14000-16000 revolutions/minute for 1-20 minutes, dispersing at 900-1100 W for 1-20 minutes to obtain uniformly dispersed nanocellulose/graphene aqueous dispersion, where amount of graphene or reduced graphene is 0.1-0.3% of the mass of the hemicellulose-containing nanocellulose aqueous solution, heating nanocellulose/graphene aqueous dispersion under stirring conditions of 600-1000 revolutions/minute, evaporating water to obtain an 10-20% aqueous dispersion, adding acetone in aqueous dispersion to make 30-40% acetone, dispersing for 1-20 minutes at 400-600 W, centrifuging at 8000-10000 revolutions/minute to obtain a precipitate, adding acetone in precipitate, dispersing under ultrasonic conditions of 500-600 W for 1-20 minutes, centrifuging at 8000-9000 revolutions/minute to obtain precipitate, where the mass ratio of the precipitate to acetone is 1:9-11, repeating for 5-6 times, and adding acetone in precipitate to obtain an acetone dispersion having solid content of 20-25%, and (iii) mixing isophorone diisocyanate and acetone dispersion, stirring uniformly, heating to 65-70 degrees C for 1-2 hours, adding polypropanol-2000 in reaction system, reacting at 65-70 degrees C for 1.5-2 hours, adding 15-25% 1,4-butanediol in acetone dropwise to the reaction system, reacting at 70-80 degrees C for 1.5-2 hours, dissolving dimethylolpropionic acid in N-methylpyrrolidone, adding in reaction system, reacting at 65-75 degrees C, controlling viscosity of the reaction solution to less than 100 mPa.S with acetone, reacting for 3.5-4 hours, adding triethylamine in reaction system, neutralizing reaction for 15-20 minutes, dispersing reaction solution by high-speed disperser to obtain hemicellulose-containing nanocellulose-dispersed graphene in-situ chemically modified aqueous polyurethane emulsion, i.e. nanocellulose-dispersed graphene chemically modified aqueous wood coating.