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Chemistry and Industry of Forest Products ›› 2021, Vol. 41 ›› Issue (4): 1-9.doi: 10.3969/j.issn.0253-2417.2021.04.001

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Preparation and Corrosion Resistance of Tannin Acid/Toughened Shellac Resin Composite Coating

Chunyin LI1,2(), Kun LI1,*(), Yanlin SUN2, Yiwen LIU3, Hong ZHANG1, Fuhou LEI4   

  1. 1. Research Institute of Resources Insects, Chinese Academy of Forestry; National Forestry and Grassland Bureau Characteristic Forest Resources Engineering Technology Research Center, Kunming 650224, China
    2. College of Chemical Engineering, Kunming University of Science and Technology, Kunming 650500, China
    3. Wufeng Chicheng Biotechnology CO., LTD.; Research Centers of Chinese Gall Effective Cultivation and Deep Processing Engineering Technology, National Forestry and Grassland Administration, Yichang 443413, China
    4. Guangxi Key Laboratory of Chemistry and Engineering of Forest Products, Guangxi Collaborative Innovation Center for Chemistry and Engineering of Forest Products, Guangxi University for Nationalities, Nanning 530006, China
  • Received:2020-09-29 Online:2021-08-28 Published:2021-08-31
  • Contact: Kun LI E-mail:licy12615@126.com;likunkm@163.com


In order to improve the toughness of shellac(SHL) resin, eleostearic acid(EA) was added to shellac resin through Diels-Alder reaction to prepare toughened shellac(TS) resin, and its structure was analyzed by gel chromatography(GPC), infrared spectroscopy(FT-IR) and 13C nuclear magnetic resonance(13C NMR). And then, tannic acid(TA) was added to prepare SHL-TA, and TS-TA composite coating. The effects of TA and EA on the anti-corrosion properties of shellac resin coating were analyzed by electrochemical workstation, neutral salt water resistance and neutral salt spray(NSS) resistance tests. The results showed that the TS modified by EA through the Diels-Alder reaction exhibited good toughness. When the weight ratio of SHL and EA was 1.8:1, the elongation at break of TS-3 coating was as high as 381.81%. In addition, the hydrophobicity of shellac coating was increased by the modification of EA, and its static water contact angle reached 95.01°.The addition of TA could improve the adhesion of the coating on the metal substrate, and the combined action of TA and EA could enhance the anti-corrosion of SHL coating. The best corrosion protection system was TS-3-TA coating. After immersion in 3.5% NaCl for 48 h, the polarization resistance of the coating was still 36.3 kΩ, far more higher than that of other coatings. And the time of neutral salt water resistance and neutral salt spray(NSS) resistance tests of TS-3-TA, which was prepared in alkali system, was 120 h and 168 h.

Key words: eleostearic acid, toughened shellac resin, tannin acid, anticorrosion coating

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