Development of etching process of DLC films in PET bottles

近年来，类金刚石(DLC)薄膜被沉积在聚对苯二甲酸乙二醇酯(PET)瓶壁上，以防止二氧化碳气体穿透和抗紫外线照射变质。然而，在聚酯瓶的回收过程中，类金刚石薄膜会受到污染。为了回收沉积在类金刚石薄膜中的PET瓶，在回收过程的早期阶段将类金刚石薄膜移除是非常必要的。由于碳膜与等离子体中的氧自由基和离子发生强烈的反应，所以采用氧气辉光放电等离子体对DLC膜进行化学刻蚀。用拉曼光谱研究了沉积在PET材料上的类金刚石薄膜的刻蚀过程。拉曼光谱证实了类金刚石膜的完全去除。刻蚀深度随刻蚀时间的延长而增加，在最佳条件下的刻蚀速率约为50 nm/min。原子力显微镜观察了不同刻蚀时间的腐蚀处理后的PET表面状况。在氧等离子体作用下，完全去除PET的DLC膜的表面粗糙度与纯PET基片的表面粗糙度基本相同。

Recently, the diamond-like carbon (DLC) films are deposited in the wall of the polyethylene terephthalate (PET) bottles because of the protection for carbon dioxide gas penetration and deterioration against ultraviolet irradiation. However the DLC films fall into the contamination through the recycling process of PET bottle. In order to recycle the PET bottles deposited in DLC films, it is quite necessary to remove the DLC films at the early stage of recycling process. The DLC films were chemically etched by the glow discharge plasma of oxygen gas because carbon films were greatly reacted by the oxygen radicals and ions in the plasma. The etching of the DLC films deposited on the PET materials has been investigated using Raman spectroscopy. The complete removal of the DLC films was confirmed by Raman spectra. The etching depth increases with the etching time and the etching rate at optimum condition is approximately 50 nm/min. Atomic force microscopy observation was relieved surface condition of the PET after the etching treatment at different etching time. The surface roughness of the PET completely removed DLC films is almost same as the pure PET substrate without the exposure of oxygen plasma.