桉木透明涂饰漆膜耐光性的研究

Light Fastness of Clear Painted Varnish Film on Eucalyptus Wood

采用硝基外用清漆、聚氨酯清漆和醇酸树脂清漆对细叶桉、赤桉、巨桉、尾叶桉、粗皮桉和大花序桉进行涂饰处理,在紫外老化的作用下,通过测定试样表面色度学和光泽度参数,对3种涂膜的耐光性进行研究。结果表明:1)6种桉木经清漆涂刷后,桉木漆膜表面的亮度随着光照时间的增加均呈下降趋势。细叶桉和粗皮桉亮度较低,赤桉、巨桉、尾叶桉、大花序桉亮度较高。黄色指数随着光照时间的增加呈上升趋势,光照时间越长,黄化现象越严重。总色差随着光照时间的增加呈下降趋势,但变化不明显。细叶桉总色差变化最小,巨桉总色差变化最大。2)漆膜随着光照时间的增加,漆膜劣化程度越来越明显,光泽度均有小幅下降趋势,但变化均不明显。3)3种清漆均发生劣化变色,醇酸树脂清漆的耐光性最好,聚氨酯清漆次之,硝基外用清漆最差。建议用户在选择清漆涂饰时,应加入抗紫外光的吸收剂等提高漆膜的耐光性,或者选用耐光性能改良过的木材加以使用,实现木材的耐光性和耐久性。

Woods of 6 Eucalyptus trees(including E.tereticornis,E.camaldulensis,E.grandis,E.urophylla,E.pellita,and E.cloeziana)were painted by nitrocellulose varnish,polyurethane varnish and alkyd varnish,which were subjected to UV irradiation to examine the light fastness of 3 films by testing chromatics and glossiness parameters.The results showed that:1)the brightness of the films painted on the surface of eucalyptus wood decreased with the time of irradiation.Brightness was lower on E.tereticornis and E.pellita woods,and the others were higher.The yellow index increased by the increase of irradiation time,the longer the irradiation time,the more serious the etiolation.The color difference decreased with the increase of irradiation time,but the change was not obvious.2)The degradation of three films was more and more obvious with irradiation time,glossiness had a slight decrease,but the change was not obvious.3)Degradation occurred in three vanishes,among them,the best light fastness was alkyd varnish and the worst was nitrocellulose varnish.It was suggested that in order to improve the light fastness of the varnishes,the light stabilizer or absorber against the UV light irradiation should be added into the varnishes when they were used,or the modified wood of light resistance could be used to improve wood light fastness and durability.