含有紫外光安定劑舉塗膜劣化之研究

Degradation of Coatings Containing UV-Stabilizers

張上鎮(Shang-Tzen Chang)

《林業試驗所研究報告季刊》 2卷2期 (1987/06) Pp. 165-185

https://doi.org/10.7075/BTFRI.198706.0165

摘要

塗膜很容易受紫外光的影響而劣化，本試驗的主要目的是研究紫外光安定劑添加入塗料中對於塗膜耐光性之影響，並研究塗膜受紫外光作用所產生之劣化。本試驗使用二種紫外光安定劑，即2, 4-雙羥基二甲苯酮(HBP)與2-氰基-3, 3-二苯基丙烯酸乙酯(ECPA)分別添加於硝化纖維素粒卡塗料(NC)與聚聚酯塗料(PU)中，以此作爲防止臺灣杉表面色變之保護劑。以掃瞄電子顯微鏡、X光能量散射分析儀進行檢視與分析塗膜表面之變化情形，試驗結果顯示含有紫外光安定劑之塗料系統不但不能發揮共保護功效，抑止臺灣杉的色變，相反地，反而加速塗膜的劣化。此乃因爲紫外光安定劑與塗料樹脂的相容性不好，故含有紫外光安定劑之塗膜靜置於常溫室內一段時間後，卽産生分離作用，紫外光安定劑單獨或是與塗料中矽類添加物結合後，慢慢地析出於塗膜表面，先集聚成塊狀、片狀或長條狀的構造物，然後再分裂成顆粒狀的類似結晶物，如果將含有紫外光安定劑之塗膜曝露於紫外光下，則受紫外光之影響而加速了紫外光安定劑與塗料樹脂之分離作用，使得塗料樹脂亦遭受破壞，而塗膜表面則佈滿容易剝離的顆粒狀類似結晶物，這些顆粒狀的類似結晶物經由光譜分析確知爲紫外光安定劑，換言之，含有紫外光安定劑之塗膜受光之作用會劣化成佈滿顆粒狀紫外光安定劑之表面。

關鍵字

塗料 ； 紫外光安定劑 ； 掃瞄電子顯微鏡 ； X光能量散射分析 ； 紅外線光譜分析 ； 光劣化 ； 相容性 ； 類似結晶物

並列摘要

The objective of this study was to determine the effect of ultraviolet stabilizers on the performance of clear coating films in the prevention of discoloration of Taiwania cryptomerioides lumber. It was accomplished by using scanning electron microscope (SEM), energy dispersive X-ray analysis (EDXA) technique and infrared (IR) spectroscope. Clear coating systems studied were nitrocellulose (NC) and polyurethane (PU) consisted of 2, 4-dihydroxy-benzophenone (IIBP) or ethyl-2-cyano-3, 3-diphenylacrylate (ECPA) which functioned as an ultraviolet absorber.
SEM observations showed that crystalline particles appeared on the coating films studied as it was exposed to ambient conditions or ultraviolet light. The EDXA technique revealed silicon signals from the silicone-type additives in the crystalline particles. Further analysis with infrared spectroscope demonstrated that the crystalline particles were actually the ultraviolet stabilizers.
Conclusions drawn from these findings are as follows:
1. Due to their incompatibility, ultraviolet stabilizers, whether alone or combined with silicone-type additives, separate from coating resins in the form of crystalline particles.
2. This separation is accelerated by the exposure to ultraviolet light.
3. The clear coating systems containing the aforementioned ultraviolet stabilizers are vulnerable to the deleterious effects of ultraviolet light and therefore are rendered inoperative in the protection against discoloration of Taiwania cryptomerioides lumber.

並列關鍵字

Nitrocellulose ； polyurethane ； ultraviolet stabilizers ； SEM ； EDXA ； IR ； discoloration ； degradation ； incompatability, crystalline particle ； silicon ； separation ； Taiwania cryptomerioides Hay