TiO_2添加量對精製漆耐光性改善及塗膜性質之影響

EFFECTS OF ADDING AMOUNTS OF TIO_2 ON THE LIGHTFASTNESS IMPROVEMENT AND FILM PROPERTIES OF REFINED ORIENTAL LACQUER

李佳臻(Jia-Jhen Lee) ； 盧崑宗(Kun-Tsung Lu)

《中華林學季刊》 52卷1期 (2019/01) Pp. 17-34

摘要

精製漆（Refined oriental lacquer）是將生漆（Oriental lacquer）攪拌加熱脫水而得的天然高分子塗料，其塗膜具溫潤色澤、優越的耐藥品及耐久性等，但因含芳香環結構之漆酚聚合體，導致塗膜耐光性不佳；為改善精製漆耐光性，本研究依精製漆固形分分別添加0、1、2、3、5、10、15、20及30 phr之微米級金紅石型二氧化鈦（TiO_2）至精製漆中，探討其不同添加量對精製漆耐光性之改善效益，及對塗料與塗膜性質之影響。試驗結果發現，TiO_2添加量達10 phr以上者已失去精製漆原有之色澤；未添加TiO_2精製漆之塗膜經UV光照射192 hr之色差值（Color difference, ΔE*）、明度差值（Brightness difference, ΔL*）及黃色指數差值（Yellowness difference, ΔYI），分別為31.1、10.7及99.0，而添加少量之1 phr即可明顯改善精製漆塗膜耐光性，其ΔE*、ΔL*及ΔYI值分別為15.0、6.2及54.6；同時以SEM觀察塗膜表面樹膠質析出減少；又由FTIR分析可知，精製漆塗膜之光劣化主要發生於漆酚苯環及其側鏈結構，而添加TiO_2即可減少光劣化現象；又添加1 phr之TiO_2即可獲得良好之耐衝擊性、抗彎曲性、附著性及耐熱性等均衡的塗膜性質。

關鍵字

生漆 ； 精製漆 ； 耐光性 ； 二氧化鈦

並列摘要

The refined oriental lacquer, obtained from oriental lacquer by heating with agitation and dehydration, is a natural polymeric coating which possesses a satiny texture and excellent chemical resistance and durability of film. However, its film contains aromatic urushiol polymeric structure which results in poor lightfastness. In this study, for improving the lightfastness of refined oriental lacquer, a micrometer rutile titanium dioxide (TiO_2) of 0, 1, 2, 3, 5, 10, 15, 20 and 30 phr (by wt. of solid content of refined oriental lacquer) was added to the refined oriental lacquer, respectively. The effects of adding amounts of TiO_2 on the lightfastness improved efficiency and the coating and film properties of refined oriental lacquer were examined. The results showed that the color and gloss of refined oriental lacquer would be lost on the adding amounts of TiO_2 over 10 phr. The color difference (ΔE*), brightness difference (ΔL*) and yellowness difference (ΔYI) of refined oriental lacquer film without adding TiO_2 were 31.1, 10.7 and 99.0, respectively, after UV exposure of 192 hrs. Furthermore, the lightfastness of refined oriental lacquer could be improved significantly by adding only 1 phr of TiO_2 and its ΔE*, ΔL* and ΔYI were 15.0, 6.2 and 54.6, respectively. At the same time, the gum separated out to the surface of film decreased by SEM inspection. According to FTIR analysis, the major photodegradation of the refined oriental lacquer film occurred in the benzene ring and side chain structure of urushiol which could be slowed down by adding TiO_2. Meanwhile, the film with 1 phr TiO_2 added had excellent balance properties between impact resistance, bending resistance, adhesion, heat resistance and other performances.

並列關鍵字

Oriental lacquer ； Refined oriental lacquer ； Lightfastness ； Titanium dioxide (TiO_2)