▎ 摘　　要

NOVELTY - Preparing large biological coating containing tea biologically active ingredient comprises (i) drying the tea leaves a, grinding and sieving to obtain tea powder, mixing the tea powder with ethanol, and using ultrasound-assisted ethanol extraction method to extract tea polyphenols, filtering the extract, concentrating, and freeze-drying; (ii) mixing graphite powder and sodium nitrate, adding concentrated sulfuric acid, adding potassium permanganate and stirring, adding deionized water twice the volume of concentrated sulfuric acid, heating, stirring, adding hydrogen peroxide, filtering, and washing with deionized water and 5% hydrochloric acid to neutrality, centrifuging and fully drying in a 60 degrees C vacuum drying oven to obtain graphite oxide, dispersing the graphite oxide in water to obtain a brown-yellow solution, and adding the tea polyphenol powder into the graphene solution, ultrasonically treating, and stirring, diluting the dispersion, and removing excess tea polyphenols. USE - Th method is useful for preparing large biological coating containing tea biologically active ingredient. ADVANTAGE - The method uses tea polyphenol molecules to modify the surface of graphene, solves the problem of graphene agglomeration, and significantly improves the performance of the large biological coating containing tea biologically active ingredients, has simple process, good industrial production prospects and great economic value and is economical. DETAILED DESCRIPTION - Preparing large biological coating containing tea biologically active ingredient comprises (i) drying the tea leaves at 40-45 degrees C, grinding and sieving to obtain tea powder with an average particle size of less than or equal to 180 mu m, mixing the tea powder with ethanol, and using ultrasound-assisted ethanol extraction method to extract tea polyphenols, filtering the extract, concentrating, and freeze-drying to obtain tea polyphenol powder; (ii) mixing graphite powder and sodium nitrate, adding proper amount of concentrated sulfuric acid and stirring in an ice bath for 30 minutes, adding proper amount of potassium permanganate and continuously stirring for 60 minutes, transferring the reaction solution to a 40 degrees C warm water bath to continue the reaction for 30 minutes, slowly adding deionized water twice the volume of concentrated sulfuric acid, heating the system to 98 degrees C, stirring for 5 minutes, adding hydrogen peroxide until no bubbles are generated, filtering while hot, and washing with deionized water and 5% hydrochloric acid to neutrality, centrifuging and fully drying in a 60 degrees C vacuum drying oven to obtain graphite oxide, dispersing the graphite oxide in water to obtain a brown-yellow solution, and ultrasonically treating for 1 hour to obtain a graphene solution, adding the tea polyphenol powder into the graphene solution, ultrasonically treating at 60 degrees C for 12 hours, and continuously stirring the dispersion during the treatment, after the ultrasonic treatment is completed, diluting the dispersion, and removing excess tea polyphenols by centrifugation and freeze-drying the dispersion to obtain graphene modified by tea polyphenols; (iii) placing the modified graphene in an ethanol solution, ultrasonically dispersing for 30-45 minutes, and magnetically stirring for 5-10 minutes, weighing aqueous polyurethane, slowly adding the modified graphene dispersion suspension at a speed of 200 revolutions/minute, increasing the speed to 850-1000 revolutions/minute, stirring for 45-60 minutes, reducing the speed to 200 revolutions/minute, and continuously stirring for 30-15 minutes. An INDEPENDENT CLAIM is also included for: a method large biological coating containing tea biologically active ingredient prepared by the above method.