旧新闻纸脱墨浆调色机理的研究

Study on the Toning Mechanism of Old Newsprint Deinked Pulps

以CIE(国际照明委员会)色度空间理论为基础,首先研究CIE LAB与s RGB(通用色彩标准)色度系统之间的转化过程,并利用MAT LAB程序实现快速转化与显示,将抽象的CIE LAB色度空间值转化为能够在绝大多数电子设备上显示的直观的颜色。然后,利用染料和荧光增白剂对以脱墨浆的调色机理进行了研究。结果发现:紫色染料对L*和b*值的影响最大,染料用量越大,纸浆的亮度就越低,颜色向蓝色方向偏移;红色染料对a*值的影响最大,红色染料用量越大,a*值越小,颜色向绿色方面偏移。荧光增白剂的加入虽在一定程度上提高a*值,降低b*值,但对纸浆的亮度几乎没有影响。要改善纸张的颜色,最根本的是提高纸浆本身的白度,而不能采用加入荧光增白剂的方法来解决。

The conversion of CIELAB into standard RGB（sRGB） color space was investigated, based on the CIE （Commission Internationale de L＇Eclairage） color space theories. The conversion procedure was integrated in a MATLAB program which can be used to conveniently convert sets of L＊a＊b＊ values into sRGB values. Thus abstract L＊a＊b＊ values could be shown on most electronic devices visually. Besides, the toning mechanism of old newsprint deinked pulps with two dyes and an optical brightening agent （OBA）. Results showed that the violet dye had significant effects on the L＊ and b＊ values of deinked pulps. The brightness （L＊） decreased with the increasing dosage of the violet dye, and the color of handsheets shifted to blue. As expected, the red dye used has a very positive effect on a＊ values. An increase in red dye load would lead to greener handsheets. The OBA used had only a slightly positive effect on L＊ value, although it could to some extent result in an increase in a＊ values and a decrease in b＊ values. Based on the results, in order to improve the tone of deinked pulps, the essential measure is to increase the brightness of pulps, instead of adding OBAs.