Synthesis And Application Of Modified Vegetable Oils In Water Repellent Finishing Of Cotton Fabrics

Water repellent finishing is an important aspect in functional finishing. At present, the most widely used water-repellent agents are silicone agents and organic fluorine agents. However, silicones increase pilling, and their wastewater are harmful to aqua-life. Comparatively, fluorocarbon compounds can significantly lower surface energy when applied on surfaces of materials and bring remarkable water repellency, and they have been paid more attention by the market for its unique water and oil repellency, anti-soiling ability and durability to washing, dry cleaning and climate. But cotton fabrics treated with organic fluorine agents have bad hydrophilicity and are incline to produce static electricity, which brought bad effect on the wearability. Besides, the cost of organic fluorine agents is high, people have realized that the long chain organic fluorine agents do harm to enviroment and people’s health. Consequently, developing an enviromental friendly, durable and harmless water-repellent agent is of great importance.Vegetable oils are bio energy resources and because of the long carbon chains, they are somewhat water repellent, but there is still great gap compared with the effect of traditional water-repellent agents. Introduction of C-F bond to the oil can further reduce surface energy at fiber surface, which may produce fabrics with improved water repellency at lower cost with less resource consumption and pollution.Four vegetable oils （castor oil, palm oil, soybean oil and peanut oil） were used and modified to impart hydrophobicity to cotton fabrics. Main researches are as follows:（1） The main physical chemistry characteristics of four vegetable oils were analyzed through measuring the acid value, saponification value and iodine value to find out characteristics of potential plant that are suitable for further treatment and modification. （2） The effect of directly using vegetable oils as water repellent agents was tested. Two ways were adopted. One, different vegetable oils were emulsified with sulfonated castor oil as emulsifier. Two, different vegetable oils were dissolved with acetone. The results showed that the cotton fabrics treated with vegetable oils had good water repellency.（3） Different fluorine containing fatty acid esters were synthesized by modifying several vegetable oils-castor oil, palm oil and soybean oil, through alkaline hydrolysis, acidification, acylation and reaction with 2, 2, 2-trifluoro ethanol. The synthesis method of each modified oil was almost the same and was investigated with orthogonal experiment and single factor experiment. The structues were characterized by FT-IR, ¹H NMR, ¹⁹F NMR and MS. It can be seen that the short fluorine chain was grafted on the carbon chains of vegetable oils.（4） The effect of modified vegetable oils and their impact on the whiteness, breaking strength, permeability of the fabrics and structures of the fiber were tested. The finishing processes were optimized based on the hydrophobicity of the treated cotton fabrics indicated by contact angle, time for water to disappear, breaking strength and the whiteness. The results showed that the cotton fabrics treated with the modified vegetable oils demonstrated excellent water repellency, without significantly compromising the whiteness, breaking strength and permeability of the fabrics, indicating the modified vegetable oils had little bad effct on fabrics’ performance. The cotton fabrics treated with the modified palm oil exhibited the highest water repellency among all treated fabrics. All the treated fabrics showed good durability of water repellency. Even after 5 cycles of washing, the contact angle remained about 90°or even higher. The cotton fabric treated with modified soybean oil demonstrated the best durability of imparted hydrophobicity.