| ZHANG Xiuli,FENG Rukang,WU Yongling,LIU Zhilan,WU Diben,ZHENG Hongyu.Preparation and Anti-sticking Properties of Rubber Mold Surface Coating by Sol-gel Method[J],53(16):229-239 |
| Preparation and Anti-sticking Properties of Rubber Mold Surface Coating by Sol-gel Method |
| Received:September 03, 2023 Revised:January 05, 2024 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2024.16.020 |
| KeyWord:sol-gel method coating rubber mold anti-sticking property durability |
| Author | Institution |
| ZHANG Xiuli |
School of Mechanical Engineering, Shandong University of Technology, Shandong Zibo , China;Shandong Provincial Key Laboratory of Precision Manufacturing and Non-traditional Machining, Shandong Zibo , China |
| FENG Rukang |
School of Mechanical Engineering, Shandong University of Technology, Shandong Zibo , China |
| WU Yongling |
School of Mechanical Engineering, Shandong University of Technology, Shandong Zibo , China;Shandong Provincial Key Laboratory of Precision Manufacturing and Non-traditional Machining, Shandong Zibo , China |
| LIU Zhilan |
Shandong Provincial Key Laboratory of Core Tire Mold Technology, Shandong Gaomi , China |
| WU Diben |
Shandong Provincial Key Laboratory of Core Tire Mold Technology, Shandong Gaomi , China |
| ZHENG Hongyu |
School of Mechanical Engineering, Shandong University of Technology, Shandong Zibo , China |
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| Abstract: |
| As the type 45 steel rubber mold is easy to be contaminated and the fluororesin coated mold is expensive, the work aims to prepare the anti-sticking coating on rubber mold based on the sol-gel method, and investigate the anti-sticking property and durability of the coating. With silica sol and methyl triethoxysilane (MTES) as the main raw materials, sol-gel coating was prepared on the type 45 steel mold samples. Fluoroalkyl silane modified sol-gel coating and fluoroalkyl silane surface treatment coating were also prepared for comparison with the non-fluorine sol-gel coating. The anti-sticking property and durability of the coatings were investigated by rubber vulcanization tests. The changes of surface micro morphology and element composition of the samples with the number of vulcanization tests were studied by scanning electron microscope and energy dispersive spectrometer. The adhesion process of rubber on the coating surface was investigated. The results showed that the sol-gel coating was composed of O, Si, C, and Ti, with good film forming property. Its vulcanization release force was about 20 N, similar to that of the PTFE coating. The element composition changed little after 10 vulcanization tests, indicating that it had good anti-fouling performance. The fluoroalkyl silane modified sol-gel coating was composed of O, Si, C, Ti, and F. The element F reduced the adhesion between the coating and the substrate, which might lead to cracking and spalling of the coating during the vulcanization tests. The fluoroalkyl silane surface treatment coating could reduce the surface energy and the release force, but the fluoroalkyl silane film was easy to stick to the rubber and pollute the products. The sol-gel coating was more applicable to rubber molds compared with the fluoroalkyl silane modified sol-gel coating and fluoroalkyl silane surface treatment coating. The results of the durability test showed that the type 45 steel surface became yellow after 100 vulcanization tests, with different brightness at different positions, and turned brown after 300 tests. However, the surface color of the sol-gel coating changed little after 200 vulcanization tests, turned light yellow after 300 tests, and became brown after 500 tests. The variation of Zn element mass content with the number of vulcanization tests indicated that the sol-gel coating could be used approximately 300 times more than the type 45 steel mold for rubber vulcanization, increasing the continuous service life of the mold 2-3 times. The adhesion and accumulation of rubber contaminants on the surface of the mold were related to the flow of rubber during vulcanization. In areas where the rubber flow speed was low, the micro morphology of rubber pollutants appeared as a textured pattern. While in the high flow rate area, rubber pollutants initially appeared as flakes, gradually thickened with increasing vulcanization times, and then cracked along the flow direction, developing into blocks. The different micro morphologies led to the different appearance at different positions, and affected the surface quality of the rubber products. Thus, reducing the rubber flow will improve the surface brightness uniformity of the products. Although the service life of the sol-gel coating is shorter than that of the fluororesin anti-sticking coating, it has the advantages of environmental friendliness (free of toxic and refractory substances such as perfluorooctanoic acid), low film forming temperature, low carbon consumption, low cost, and easy cleaning. The sol-gel coating has broad application prospects in rubber molds. |
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