未加填和加填纸张的光散射系数

Light Scattering Coefficient of Filled and Unfilled Paper Sheets

对未加填和加填纸张的光散射系数进行了研究。未加填纸张的光散射系数与纸浆种类、磨浆（或打浆）和湿压的程度、成形条件等有关。加填增加纸张的不透明度和亮度是由于增加了纸张的光散射系数。填料的光散射效能取决于它的折射指数和粒度。文中对填料的最佳程度和加填纸光散射系数的表达式进行了详细的讨论。

It is well-known that the light scattering coefficient of an unfilled paper sheet depends highly on the void area in the sheet,i. e. the interfacial area between the fibres and air. Well-bonded sheets resulted from highly beaten low freeness stocks would evidently lead to less fibres-air interfaces. It is also known that light scattering in a paper sheet is inversely and linearly proportional to the degree of fibre bonding. Wet pressing would also retard light scattering,as fibers are forced to more compactness and closer contact. In the case of filled paper sheets,however,fillers tend to occupy the voids between fibres,leading to a decrease in strength properties but an increase in light scattering,the degree of which depends highly on the refractive index of the pigment filler employed and its particle size. For any specific pigment of a definite light scattering coefficient,it is obvious that the particle size of the pigment acts as the controlling factor the final filled sheet for its light scattering. Optimization of particle size of pigment fillers is being discussed to the end of obtaining optimum light scattering performances. Evidently,the light scattering of a filled paper sheet will rely on the optimal properties of the pigment employed as well as on the lower degrees of bonding of fibres. It is proposed that corrected light scattering coefficients for fibres and pigments should be used when the conventional light scattering coefficient expression is employed to predict or verify the optical properties of filled paper sheets.