Study On Improving Oil Resistance And Extraction Performance Of Thermoplastic Polyurethane Anti Ultraviolet Aging Agent

Thermoplastic polyurethane（TPU）has outstanding wear resistance and fatigue resistance,good oil resistance and chemical reagent resistance,excellent mechanical properties and easy processing.It is most widely used in the rubber layer materials of oil storage and transportation equipment.During the outdoor use of oil equipment,it will be affected by ultraviolet light,which causes the aging of TPU materials.At present,the main way to improve UV stability of TPU is adding organic anti-UV aging agent.However,because of the long-term contact with oil,the organic anti-UV aging agent in TPU will be dissolved with the impregnation and penetration of oil,which would not only destroy the structure of TPU materials,accelerate the UV aging process,but also cause oil pollution,and thus seriously affect the use of oil.To solve the problem,this work aim on the improvement of oil extraction resistance of anti-UV aging agent of TPU.The organic UV absorber 2-（2-hydroxy-5-benzyl）benzotriazole（UVP）was grafted onto inorganic nano titanium dioxide（nano-Ti O₂）particles to promote the oil extraction resistance.The main research contents and conclusions are as follows:First of all,the composites of anti-UV aging agent and nano-Ti O₂（Ti O₂-g-UVP）was obtained by solid-phase grafting.UVP was grated to the dispersed nano-Ti O₂ by fast rate mechanical shear at high temperature,which benefited the activation of UVP molecules.Various tests and characterization showed that the grafting rate of UVP was around 9.5%,and the microstructure observation ensured that the dispersion of nano-Ti O₂ in TPU matrix was significantly improved after grafting.In order to investiage the UV resistance of Ti O₂-g-UVP,UVP,nano-Ti O₂ and Ti O₂-g-UVP were respectively mixed into TPU and processed into thin films for comparsion study.Meanwhile,Ti O₂ and UVP were together blended into TPU as the control according to the grafting rate.A UV aging test cycle lasting for 300h was carried out.The results indicated that UVP has good UV absorption ability.What is more,Ti O₂-g-UVP could not only maintain good UV resistance,but also realize the synergy between nano-Ti O₂and UVP compared with a single component.Then,the oil extraction resistance of Ti O₂-g-UVP was explored and evaluated.After soaking and extraction operations with simulated fuel B solution,UV accelerated aging test was carried out.The results showed that the properties of TPU/UVP samples decreased seriously after oil extraction,and the oil resistance of TPU/Ti O₂ samples remained limited.Hovever,the TPU/Ti O₂-g-UVP samples displayed the best oil resistance and UV aging resistance among all.The analysis of extraction B solution showed that the retention rate of UVP in TPU was rather high,while the extraction rate of Ti O₂-g-UVP was only 3.7%.Finally,the application research of TPU was carried out to investigate the effect of anti-UV aging agent Ti O₂-g-UVP on the coloring of TPU.Dye-TPU and Dye-TPU/Ti O₂-g-UVP samples were obtained by coloring with masterbatch,and tested for color difference,mechanical properties and dispersibility.The results show that the Dye-TPU/Ti O₂-g-UVP sample not only exhibits good oil resistance and UV resistance,but also has better coloring effect and higher color saturation.