提高新闻纸不透明度的措施

Measures to improve newsprint opacity

不透明度是新闻纸的一项重要指标。降低新闻纸的定量及提高纸张的白度,则会造成不透明度的下降。为了生产高不透明度、低定量并且白度达到65%的新闻纸,可采用下述三种方法:一是在新闻纸配料中添加填料改善纸张的不透明度,填料必须具有较高的光散射能力和孔隙率,添加量较低;其二是通过添加荧光增白剂来获得较高的白度而不损失不透明度;其三是当脱墨浆作为新闻纸的主要原料时,为获得较高的不透明度,建议采用较高的漂白温度、较低的pH,且在热分散或漂白后进行后浮选。

Opacity is an important characteristic of newsprint.When the basis weight is decreased and the brightness of the paper is increased,the opacity of newsprint will inevitably be reduced.In order to produce high opacity and low basis weight newsprint with 65% brightness,three methods can be employed.First,fillers are added in the newsprint furnish to improve newsprint opacity,the filler must have high light scattering ability and high porosity,with a relatively low loading dosage.Second,fluorescent whitening agents（FWA） are used to achieve higher whiteness without the loss of opacity.The third,when deinking pulp is used as the main furnish of newsprint,it is suggested that bleaching temperature should be high and pH should be low,and that a post-flotation can be followed after kneading or bleaching to obtain higher opacity.