Increased Filler Levels in Alkaline Paper Using PCC Technology, 1992 Papermakers Conference Proceedings

Considerable interest exists in achieving more filler for fiber substitution in alkaline paper. However, papermakers are limited by losses in strength, stiffness, and sizing which occur at increased filler levels. Other limitations include dusting or linting, and changes in drainage and de-watering. By altering precipitated calcium carbonate (PCC) particle size and morphology with existing PCC technology, these problems can be minimized.

PCC’s having scalenohedral morphology are widely used in paper filling applications due to their superior optical and bulking properties. These scalenohedral PCC’s are often optimized for opacity, resulting in unacceptable losses in strength and/or sizing at increased filler levels. Increasing the average particle size of calenohedral PCC or blending PCC’s of different average particle size will provide improvements in strength and sizing, allowing for increased filler usage.

Solid particle PCC morphologies provide a further opportunity for higher filler levels in paper. Of particular interest are PCC’s having a prismatic morphology. This solid particle PCC offers excellent strength, stiffness and sizing as well as superior drainage and dewatering characteristics.

Blends of scalenohedral and prismatic PCC can provide a balance of strength, optics, and sizing.

Pilot papermachine and handsheet study results are presented to illustrate PCC approaches to higher filler levels.