▎ 摘　　要

NOVELTY - Coating comprises 40-60 pts. wt. polyurethane emulsion, 1-2 pts. wt. antifoaming agent, 20-30 pts. wt. film-forming auxiliary agent, 0.5-1 pts. wt. flatting agent, 4-8 pts. wt. dispersant, 2-4 pts. wt. wetting agent and 5-8 pts. wt. water, where the polyurethane emulsion is prepared by using aminoporphyrin grafted titanium dioxide as chain extender. The amino porphyrin grafted titanium dioxide is prepared by reacting 5, 10, 15, 20-tetra (4-aminobenzene)-21H, 23H-porphyrin in amino and acyl chloride in titanium dioxide. The acyl chloride titanium dioxide is prepared by acyl chlorination of hydrophilic titanium dioxide. USE - Used as coating containing polyurethane. ADVANTAGE - The coating: enhance the visible light absorption of titanium dioxide; promote the separation of photo generated electron hole pair; and improves the performance of the titanium dioxide for catalyzing and degrading formaldehyde. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparing the coating comprising (i) adding hydrophilic nano titanium dioxide into an anhydrous toluene solvent, continuing to add trimesoyl chloride after uniform ultrasonic dispersion, stirring and reacting at constant temperature in a nitrogen atmosphere, centrifuging, washing and drying a product to obtain acyl chloride nano titanium dioxide, adding acyl chloride nano titanium dioxide into a dichloromethane solvent, continuously adding 5,10,15, 20-tetra (4-aminobenzene)-21H, 23H-porphyrin and triethylamine after uniform ultrasonic dispersion, transferring the mixture into an oil bath pot for amidation reaction, cooling a product, centrifuging, washing and drying to obtain amino porphyrin grafted titanium dioxide chain extender, (ii) heating polypropylene glycol for vacuum dehydration, adding isophorone diisocyanate, heating to 80degrees Celsius in a nitrogen atmosphere, carrying out prepolymerization reaction for 2 hours, reducing the temperature to 55degrees Celsius, adding 2,2-dimethylolpropionic acid and dibutyltin dilaurate and reacting for 2 hours, adding N,N-dimethylacetamide solvent for regulating the viscosity of the solution, adding triethylamine for regulating the pH of the solution to be neutral, adding amino porphyrin grafted titanium dioxide chain extender for graft chain extension reaction, carrying out reduced pressure distillation for removing the solvent, adding distilled water for high-speed emulsification, and (iii) taking the polyurethane emulsion, defoaming agent, film-forming assistant, flatting agent, dispersing agent, wetting agent and water according to the corresponding weight and mechanically stirring uniformly.