引用本文:张秀丽,刘志兰,徐秀芳,王旭,吴永玲,吴棣本.橡胶模具表面FEP涂层防粘耐久性影响因素及机理[J].中国表面工程,2024,37(1):126~136
ZHANG Xiuli,LIU Zhilan,XU Xiufang,WANG Xu,WU Yongling,WU Diben.Factors and Mechanisms Influencing the Anti-sticking Durability of FEP Coatings on Rubber Molds[J].China Surface Engineering,2024,37(1):126~136
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橡胶模具表面FEP涂层防粘耐久性影响因素及机理
张秀丽1,2, 刘志兰3,4, 徐秀芳3,4, 王旭1,2, 吴永玲1,2, 吴棣本3,4
1.山东理工大学机械工程学院 淄博 255000;2.山东省精密制造与特种加工重点实验室 淄博 255000;3.山东省轮胎模具关键技术重点实验室 高密 261000;4.山东豪迈机械科技股份有限公司 高密 261000
摘要:
防粘性失效是橡胶模具表面涂层的主要失效形式之一,但影响涂层防粘耐久性的因素和机理尚不清晰。为了提高橡胶模具表面常用氟化乙烯丙烯共聚物(FEP)涂层的使用寿命,通过橡胶硫化试验并利用 SEM 和 EDS 测试,分析试样表面微观形貌和元素成分随硫化试验次数的变化,研究溶剂体系、涂层厚度和烧结工艺对橡胶模具表面 FEP 涂层防粘耐久性的影响规律,分析各因素对涂层使用寿命的影响机理。通过 XPS 测试胶垢成分发现胶垢主要包含 Zn、S、C、O 四种元素,模具使用初期 ZnS 是胶垢的主要成分,随硫化次数增加,ZnS 层上产生有机沉积。硫化试验 300 次后,45 钢试样、双层水性 FEP 涂层和单层溶剂型 FEP 涂层试样表面 Zn 元素质量含量分别为 40.6%、0.45%和 1.13%,FEP 涂层表面胶垢出现在涂层表面缺陷处。由于双层水性 FEP 涂层更容易控制表面 FEP 树脂成膜厚度和质量,其较单层溶剂型 FEP 涂层具有更好的防粘耐久性。 涂层面层厚度和成膜质量是影响双层水性 FEP 涂层防粘耐久性的关键因素;在 300 次硫化试验范围内,烧结工艺对涂层的防粘耐久性影响不大。采用橡胶硫化试验和表面分析的方法研究橡胶模具表面涂层的防粘耐久性,探究溶剂体系、涂层厚度和烧结工艺等因素的影响,研究结果可为橡胶模具表面处理提供理论依据。
关键词:  涂层  氟树脂  防粘  耐久性  橡胶模具
DOI:10.11933/j.issn.1007-9289.20230508002
分类号:TQ330;G76
基金项目:国家自然科学基金(51905317);山东省自然科学基金(ZR2020ME047)
Factors and Mechanisms Influencing the Anti-sticking Durability of FEP Coatings on Rubber Molds
ZHANG Xiuli1,2, LIU Zhilan3,4, XU Xiufang3,4, WANG Xu1,2, WU Yongling1,2, WU Diben3,4
1.School of Mechanical Engineering, Shandong University of Technology, Zibo 255000 , China;2.Shandong Provincial Key Laboratory of Precision Manufacturing and Non-traditional Machining,Zibo 255000 , China;3.Shandong Provincial Key Laboratory of Core Tire Mold Technology, Gaomi 261000 , China;4.Himile Mechanical Science and Technology (Shandong) Co., Ltd., Gaomi 261000 , China
Abstract:
Rubber molds are widely used in the manufacturing of tires, shoe soles, seals, and stern bearings. The mold surface quality directly affects the quality and appearance of products. However, the surfaces of rubber molds are contaminated after multiple vulcanizations, causing difficulty in demolding and affecting product quality. Coatings are usually used to improve the anti-sticking performance of rubber molds in industry; however, anti-sticking failure is still one of the main failure modes of rubber mold surface coatings. The factors and mechanisms that affect the anti-sticking durability of coatings are unclear. To improve the service life of commonly used fluorinated ethylene propylene (FEP) coatings on rubber molds, coatings were prepared on flat samples using the air-spraying method, and their anti-sticking durability was evaluated using rubber vulcanization tests. The surface morphology and elemental composition of the samples were examined using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) to study the changes with the vulcanization time. A bilayer waterborne FEP coating sample and a single-layer solvent-based FEP coating sample were prepared, and their anti-sticking durabilities were compared with that of a type 45 steel sample. The results showed that Zn and S were added to the surface of the samples after the vulcanization tests. After 300 tests, the surface Zn weight concentrations of the type 45, bilayer waterborne FEP coating, and single-layer solvent-based FEP coating samples were 40.6%, 0.45%, and 1.13%, respectively. X-ray photoelectron spectra (XPS) analysis was conducted for the type 45 steel sample, and it was found that the contaminants were mainly composed of Zn, S, C, and O. ZnS was the main component of the contaminants in the beginning, and as the number of vulcanizations increased, organic deposition occurred in the ZnS layer. The contaminants on the FEP coating samples appeared at the surface defects of the coating. The surface FEP resin film thickness and quality are easier to control for the bilayer waterborne FEP coating than for the single-layer solvent-based FEP coating; thus, the bilayer waterborne FEP coating has better anti-sticking durability. Three bilayer waterborne FEP coating samples with different coating thicknesses (T1: 13.7 μm, T2: 20.4 μm, T3: 29 μm) were prepared by changing the thickness of the topcoat, and their anti-sticking durability was studied and compared. The results showed that the increase in the Zn concentration on the surface of the T1 sample was more significant than those of the T2 and T3 samples, indicating that the topcoat thickness and film quality are the key factors affecting the anti-sticking durability of the bilayer waterborne FEP coating. Bilayer waterborne FEP coating samples with different sintering processes were prepared by changing the sintering temperature (340 ℃ and 380 ℃) and using a cooling method (furnace cooling, air cooling, and water quenching). The Fourier-transform infrared spectra (FTIR) of the coating samples were obtained, and it was deduced that the sintering process of the coating had a slight effect on the molecular structure of the FEP resin but had an effect on the crystallinity. The water-quenching and air-cooling methods resulted in lower crystallinity of the FEP resin than the furnace-cooling method. The results of the anti-sticking durability test showed that, within 300 vulcanization tests, the sintering process had a slight effect on the anti-sticking durability of the bilayer waterborne FEP coating. The research results provide a theoretical basis for the anti-sticking surface treatment of rubber molds.
Key words:  coating  fluororesin  anti-sticking  durability  rubber mold
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