Requirements and Measurements of Sized Papers

The purpose of sizing is to modify the surface of the fibers to control penetration of aqueous liquids into the paper. The penetration usually correlates with the absorbency, repellency (hydrophobic ty), and spreading of the aqueous liquid concerned. Control of these important properties may be required for three purposes  

Control of the penetration rate of the aqueous phase in a converting operation such as size press treatment, coating, glueing (influences also the machine runnability). 

Control of liquid absorption or wetting in a printing process. 

Control of the serviceability of many grades of paper and board, e. g. milk/juice carton, packaging papers, wallpaper, printing writing papers, etc. 

Besides a certain degree of water and ink resistance the papermakers and their customers often look for improvements in dimensional stabihty, surface strength (pick and rub), internal bond, Hnting, dusting, stiffness, smoothness, porosity, or friction coefficient, depending on the converting process and use of the paper. 

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