本研究係探討將桐油藉由冰醋酸與過氧化氫(35%, v/v)於硫酸催化下製成環氧化桐油(Epoxidized Tung oil,簡稱ETO),再將ETO調配成陽離子聚合型(Cationic polymerization) UV塗料,探討反應性稀釋劑(1,4-環己烷二甲醇二乙烯醚,1,4-Cyclohexane dimethanol divinyl ether,簡稱CHDMDE)添加量及陽離子型光引發劑種類(三芳基硫型六氟磷塩,Triarylsulfonium hexafluorophosphate salt,簡稱磷塩;三芳基硫型六氟銻塩,Triarylsulfonium hexafluoroantimonate salt,簡稱銻塩)對UV塗料性質之影響。試驗結果得知,桐油以冰醋酸及過氧化氫環氧化反應10 h,可以穩定地合成黃色透明狀的環氧化桐油。將ETO/CHDMDE依100/0、90/10、80/20、70/30及60/40等重量比加以混合後,再分別加入對全量樹脂液重量5%之磷塩或銻塩光引發劑,共可得10種塗料配方;將塗料塗佈後以鹵素燈照射硬化成膜後,分析塗膜之硬度、拉伸強度、耐衝擊性、附著性、光澤度、耐久性、耐溶劑性、玻離轉移溫度及耐光性等;綜合各種塗膜性質分析結果,得知陽離子型UV塗料有優良的塗膜附著性及耐久性,尤以完全使用環氧化桐油而不添加反應稀釋劑者性質最佳,然而,此類型塗料卻是一軟韌的塗膜,硬度不足,應用於木材塗料上,仍需加以改良。
Epoxidized Tung oil (ETO) for cationic polymerization UV coatings was synthesized by reacting tung oil with glacial acetic acid and hydrogen peroxide (35%, v/v) in the presence of sulfuric acid as a catalyst. The effect of reactive diluent (1,4-cyclohexane dimethanol divinyl ether, CHDMDE) dosage and the kinds of photoinitiators (triarylsulfonium hexafluorophosphate salt and triarylsulfonium hexafluoroantimonate salt) on the properties of UV coatings were examined. The results indicated that the yellowish transparent ETO could be readily synthesized by epoxidation of the tung oil with glacial acetic acid and hydrogen peroxide for 10 h. Ten kinds of coating formulation were obtained based on the weight of ETO/CHDMDE of 100/0, 90/10, 80/20, 70/30, and 60/40 and 5% photoinitiator by the weight of total resins was added, respectively. The UV coating films were cured by exposure on the halide UV light and the films properties such as hardness, tensile strength, impact resistance, adhesion, gloss, durability, solvent resistance, glass transition temperature, and lightfastness were conducted. The results showed that the tung oil-based cationic polymerization UV coatings had excellent adhesion and durability, especially those formulations without containing reactive diluent. However, the UV coating films possessed a soft and tough characteristic and the deficiency in hardness must be further improved for wood coatings.