纸张背衬不同衬底时的光反射率的研究

Reflectance of Paper Backed by Different Backings

从理论上研究了纸张背衬不同衬底的光反射率，得出下列表达式：Ｒｂ＝Ｒｏ＋（Ｒ∞－Ｒｏ）×（１／Ｒ∞－Ｒｏ）／（１／Ｂ－Ｒｏ）（Ｂ为衬底的光反射率），该式简单实用且物理意义明确。利用上述公式，可将Ｔａｐｐｉ标准列出的Ｔａｐｐｉ不透明度Ｃ０．８９的换算公式简化，并可从理论上定性地讨论纸张不透明度与印刷透印性的关系。

In this paper, the reflectance of paper backed by different backings is studied. The following expression is suggested: Rb= Ro+ (R∞-Ro) (1/R∞-Ro)/(1/B-Ro), where B stands for the optical reflectance of the backings. With the aid of this expression, the conversion formula given in TAPPI Standard T425 om-91 for TAPPI opacity and printing opacity can be simplified. This expression is also helpful to understand the relationship between opacity and print-through.