汽车仪表板用聚氨酯搪塑粉料:组成、加工及流变性能

Polyurethane Slush Powders for Instrument Panel of Automobiles: Composition, Processing and Rheological Properties

中文关键词: 聚氨酯 搪塑 加工 流变 汽车

英文关键词: polyurethane, slush molding, processing, rheology, automobile

中文摘要:

      本工作研究了汽车仪表板用聚氨酯搪塑粉料的组成与其加工及流变性能的关系。利用傅里叶变换红外光谱仪、核磁共振波谱仪、示差扫描量热仪、扫描电镜能谱仪、X射线衍射仪、热重分析仪和激光共聚焦显微镜研究发现,商用聚氨酯搪塑粉料的主要成分为热塑性聚酯型聚氨酯,无机填料为二氧化硅、二氧化钛和高岭土等无机粒子。通过光学显微镜观察聚氨酯搪塑粉料的熔融合并过程,得到了搪塑加工过程中适宜的加工温度和塑化时间。利用流变仪的线性频率扫描实验方法研究发现,聚氨酯搪塑粉料的熔体在高频区(短时间尺度)表现为类液性(损耗模量大于储能模量),在低频区(长时间尺度)表现出类凝胶特性(储能模量与损耗模量接近,且低频区模量出现平台)。上述实验结果表明,聚氨酯搪塑粉料的组成导致其熔体具有特殊的流变性能,即搪塑粉料中的热塑性聚酯型聚氨酯赋予搪塑粉料熔体类液性,而搪塑粉料中的无机粒子与聚氨酯相互作用形成网络结构,导致其熔体在长时间尺度下具有类凝胶特性。同时,研究发现,在搪塑加工过程中(搪塑模具上下旋转),由于聚氨酯搪塑粉料的熔体在长时间尺度下的类凝胶行为,当搪塑粉料粘附在搪塑模具表面时,熔体只熔融合并而不滴落或流挂,从而得到厚度更均匀的汽车仪表板表皮。并且搪塑成型的表皮不同位置的花纹粗糙度一致性较好。

英文摘要:

      The influence of composition and processing of polyurethane slush powder for automobile instrument panel on its rheological properties was studied. The components of polyurethane slush powder were analyzed by Fourier transform infrared spectrometry, NMR spectra, differential scanning calorimeter, scanning electron microscopy spectrometer, X-Ray diffraction, thermogravimetric analysis and confocal laser scanning microscopy. It was found that the commercial polyurethane slush powder was mainly composed of thermoplastic polyester polyurethane, and inorganic fillers were consisted of silica, titanium dioxide and kaolin. The melting and merging of polyurethane slush powder under various temperatures were observed by optical microscope, and appropriate processing temperature and plasticizing duration for slush molding were obtained. The results of linear frequency sweep experiments carried out by rotational rheometer showed that the melt of polyurethane slush powder exhibited viscous-like behavior (loss modulus was larger than storage modulus) at high frequency (short-time scale), while gel-like behavior (storage modulus was close to loss modulus, and there was a plateau of moduli at low frequency) at low frequency (long-time scale). The above results indicated that the components of polyurethane slush powder endowed the melt with specific rheological characteristics. Namely, thermoplastic po-lyester polyurethane contributed to the viscous-like behavior of the melt, the network formed by the interaction between nanofillers and polyurethane resulted in the gel-like behavior of melt at long-time scale. Meanwhile, it was also found that during slush molding (the slush mold was rotated), thanks to the gel-like behavior of polyurethane slush powder melt at long-time scale, merging instead of dropping down or sagging was happened when the slush powder was adhered to the surface of mould, thus, a instrument panel skin with more uniform thickness was acquired. In addition, the roughness of patterns in various positions of slush skin was satisfactory.