PVDF/PMMA 블랜드 코팅의 기계적 물성과 내식성능에 대한 연구

Abstract

A study on the mechanical and corrosion performance of PVDF/PMMA blend coating

Yun Hwan Kim

Department of Industrial Chemistry, The Graduate School, Pukyong National University

Abstract

The industry-wide PVDF Color coated panel has a significant flexibility problem and an environmental maintenance issue due to the PVDF coating process. This defect results in a panel coating that peels off, costing extra time and money to properly maintain these panels. The PVDF Color coated panel, when coated by Coil coating, is subject to secondary reheating during the manufacturing process. The cooling method alters the product’s thermal history and results in a significant flexibility problems down-stream. A decreased amount of flexibility becomes apparent when it is stored in a warehouse for a long period of time. This issue leads to a requirement for repair and ongoing extra costs for the industry. To rectify this issue, this study focused on examining the performance of the mechanic, morphology, and corrosion elements of a blended coating system employing both a mix of PVDF and PMMA. When studying the crystallization of PVDF, crystallization only occurred during thermal water-quenching and did not appear during air cooling. Also, Maltese cross-pattern spherulite crystals were more readily observed when using a higher ratio of PVDF in the PVDF/PMMA coating film mix. When examining the blended coating, the melting & crystallization temperatures increased while there was less PMMA in the mix. It was noted that there was not any crystallization when the content of PVDF was under 40% from the mix in the test of POM DSC and XRD. On the subject of re-baking; the tensile strength of the product increased when it was given a longer re-baking time. Also, elongation decreased when the re-baking time was longer. The 60/40 mixing ratio of PVDF/PMMA resulted in the best outcome in tensile strength and elongation. On the matter of corrosion performance, after applying the EIS test, this product had the highest corrosion protection performance at 60 wt% PVDF-coated carbon steel. Two constant indicators of corrosion on steel surfaces were observed when the PVDF content was at 20 wt.%. First, a PVDF/PMMA coating with 40 wt.% First, a PVDF/PMMA coating with 40 wt.% PVDF did not show Rct and Cdl values; indicating no delamination of coating on carbon steel. Second, Rct decrease and Cdl increase were observed with an increase of immersion time for the PVDF 20wt.% coated carbon steel. This clearly demonstrated an increase of carbon steel corrosion as well as an increase of the amount of delamination of the coating.