Synthesis And Application Performance Of Vegetable Oil Based Water Repellent Agent

Water repellent finish is an important aspect of functional finishing. Organic fluorine agent can significantly reduce the surface tension of fabric and impart excellent water repellent properties. This kind of agent is highly favored by the textile market due to its superiority, such as unique water and oil repellent, stain resistant, washable, dry cleaning, weather resistant and breathable. Most of the widely used fluorinated finishing agents contain a perfluoroalkyl group (CnF2n+1, n>8). But the long fluorocarbon chains compound generates into PFOS and PFOA which are difficult to degrade and will accumulate in the human body for a long term with potential carcinogenic effects. The application of these compounds has been or will be restricted. Therefore, the development of environmentally water-repellent finishing agent which contains no long fluorocarbon segment is a very meaningful work.A class of short-chain fluorine containing vegetable oil-based water repellent agent was designed and synthesized. The agent was used to finish the cotton fabric which showed excellent water repellent performance. The research mainly contained three parts:(a) modification of vegetable oil the aim was to introduce fluorine-containing group into the vegetable oil to improve the water-repellence while retaining polymerizable double bond of the oil. and to achieve the reasonable split of the oil. The traditional preparation principle of biodiesel was adopted. First, the higher fatty acid corresponding to the oil was generated through the preparation of saponification and acidification of the oil. Then vegetable oil based trifluoroacetate was obtained by the reaction among the higher fatty acid, the acylating agent thionyl chloride and the esterification agent trifluoroethanol. FT-1R and 19F-NMR was used to characterize the structure of the intermediate product and the modified product. (b) cationic polymerization happened between soft monomer vegetable oil-based fluorine and hard monomer styrene. The initiator and polymerization mechanism was studied. The product was purred by soxhlet extraction and the yield was calculated. The glass transition temperature and thermal stability was studied by TG and DSC. The film property was researched by SEM. The ratio of soft and hard monomer suitable for textiles was screened, (c) the synthetic polymer molecules was emulsified. The cotton fabric was prepared by the polymer. The contact angle, water repellent rating, durability, whiteness and breaking strength of the treated fabric were detected. The impact of concentration, curing temperature and other conditions on performance were studied.The results showed that vegetable oil based trifluoroacetate synthesized by saponification, acidification and acylating esterified of vegetable oil was brown liquid. Then cationic polymerization was taken. While the ratio of the vegetable oil based trifluoroethyl and styrene was 1:1, the glass transition temperature of linseed oil based polymer was about 4℃ and the yield was 44%; the glass transition temperature of soybean oil based polymer was about-3℃ and the yield was 32%. When the ratio of the vegetable oil based trifluoroethyl and styrene was bellow 1:1 the fabric showed good feel, but the yield of the polymer was low. When the ratio was greater than 1:1, the conversion of the polymer was improved, but the glass transition temperature increased, which did not meet the requirement of feel and fastness. Therefore, the ratio of 1:1 was adopted. In this case, both film forming property and thermal stability could meet the requirements. The initial cleavage temperature of linseed oil based and soybean oil based polymer was 360.5℃ and 345.3℃, both showed a good thermal stability. The synthesized polymer was emulsified and then was used to finish the fabric, the result showed that vegetable oil based water-repellent agent had good water-repellent performance. When the concentration of the polymer was 35g/L, the contact angel of the fabric finished by linseed oil based agent was 146.45° and the waterproof rating was 5; the contact angel of the fabric finished by soybean oil based agent was 141.98° and the waterproof rating was 4. The contact angel changed a little after 20 washes, but decreased a lot after 30 washes. The main reason was that there was no reactive group which could react with the fiber, so the agent was semi-durable water repellent agent. The whiteness of the finished fabric declined a little, which was mainly due to the fact that the agent was brown, while the break strength was not affected.