Paper sizing by liquid-type ketene dimers. Part 2. Effects of drying methods, UV and air-blowing treatments on PCC-filled sheets

Sizing behavior of laboratory sheets prepared with two liquid-type ketene d imers (alkenylketene dimer and branched alkylketene dimer,alkenyl-KD and br anched-AKD) was studied in terms of the following aspects: precipitated CaC O3 (PCC) filler addition levels in the sheet-making, drying procedures of t he laboratory sheets, continuous air-blowing and UV irradiation treatments of the sized sheets. The sizing level clearly decreased with increased PCC addition for the liquid-type ketene dimer sizing, although sufficient amoun ts were retained in the sheets. Especially, immediate drum drying of PCC-fi lled sheets gave far lower sizing degrees than other during methods. Contin uous air-blowing and UV irradiation treatments resulted in greater reductio n in sizing degrees for the alkenyl-KD-sized sheets than for AKD-sized shee ts. The presence of PCC in the sheets enhanced such decreases. Branched-AKD showed similar sizing behavior to that of alkenyl-KD.