Use and Fiber Savings in Graphic Grades

Transcription

1 New Technology for Increased Filler Use and Fiber Savings in Graphic Grades 05/02/2011 Wi Weiguo Cheng, Ph.D Nalco Company Nalco and the logo are trademarks of Nalco Company 1 PaperCon 2011 Page 621

2 Outline Introduction Impact of Fillers on Sheet Properties Challenges of Increasing Filler Content Effects of Filler Preflocculation Technology on Sheet Properties Pilot Machine Study Commercial Application Summary 2 PaperCon 2011 Page 622

3 Fillers in Papermaking Fillers were introduced into papermaking for improving sheet properties Optical properties, print quality, smoothness Filler is much smaller than fiber Interference with fiber fiber bonding Interference with wet end chemicals Sizing agent Strength agent 3 PaperCon 2011 Page 623

4 Why Is Higher Filler Content Desired? Fiber substitution > cost savings Pulp Pric ce in US ($/ /tonne) Kraft 850$/ton; 800 PCC 100$/ton Energy savings SBSK NBHK 400 1/3/2008 6/1/ /29/2008 3/28/2009 8/25/2009 1/22/2010 6/21/2010 Time 4 PaperCon 2011 Page 624

5 Challenges in Higher Filler Usage Sheet Strength Reduction Dusting and Picking 55 strength ndex Nm/g) Sheet s (tensile in % Filler in sheet 5 PaperCon 2011 Page 625

6 More Challenges in Higher Filler Usage Sheet Properties Loss Internalsheet strength reduction Surface strength reduction Bulk loss Poor Machine Runnability Wet web strength reduction Press picking Rt Retention ti and Sheet Formation Fillers are harder to retain Increased retention chemicalsleads leads to poorformation 6 PaperCon 2011 Page 626

7 Traditional Methods of Increasing Filler Content Furnish Optimization Composition, Refining Filler Optimization PCC vs. GCC Size and morphology Wet end chemical optimization RDF program Size press formula Dry strength thadditives 7 PaperCon 2011 Page 627

8 Filler Preflocculation Technology Increase filler particle size and reduce the interference with fiber fiber bonding Untreated Filler Prefloc. Filler 8 PaperCon 2011 Page 628

9 Why Not Use Larger Sized Filler Particle? 9 PaperCon 2011 Page 629

10 Why not Use Larger Sized Filler Particle? 10 PaperCon 2011 Page 630

11 Challenges of Filler Preflocculation Proper filler flocs size and size distribution Filler flocs to be shear resistant Large shear in modern high speed paper machine Economical Hurting Sheet Strength 11 PaperCon 2011 Page 631

12 Controllable Preflocculation with Improved Particle Size Distribution Conventional lmethod New Mthd Method 12 PaperCon 2011 Page 632

13 Controllable Preflocculation with Improved Shear Stability 13 PaperCon 2011 Page 633

14 Pilot Machine Trial Conditions EuroFEX gap former pilot machine at Innventia Machine speed: 1000 m/min Grade: 75 gsm sheet at 20%, 25% and 30% ash Furnish: 85/15 eucalyptus (26 SR) / pine (22 SR) Filler: Untreated or preflocculated dispersed PCC Chemical Additives 7.5kg/tonstarch starch, 4.5kg/tonOBA OBA, 6 kg/tonakd AKD, cationic flocculant (dosage varied), 5 kg/ton microparticle 14 PaperCon 2011 Page 634

15 Effect of Preflocculation on Strength 15 PaperCon 2011 Page 635

16 Effect of Preflocculation on Opacity 16 PaperCon 2011 Page 636

17 Case Study of Commercial Application Grade: Coated freesheet, off machine coater Basis weight ihof base sheet: 106 gsm Machine Speed: 1400 m/min Filler Starting ash content: 17% Filler: 100% PCC Wet end chemicals 5 kg/ton dry strength thagent 9.5 kg/ton cationic starch 17 PaperCon 2011 Page 637

18 Effects of Preflocculation on Sheet Properties Highlights: Ash content increased from 17% to 22%, or 5% Critical sheet strength properties were maintained Opacity increased Bulk loss was 1.5%, which was recovered by furnish optimization Tear and stiffness decreased slightly, but within specs 400% ROI 18 PaperCon 2011 Page 638

19 Steam Reduction with Increased Filler Content Treatment started 19 PaperCon 2011 Page 639

20 Steam Reduction with Increased Filler Content 20 PaperCon 2011 Page 640

21 Impact on First Draw Treatment started 21 PaperCon 2011 Page 641

22 Summary With increasing fiber prices, increasing the ash content in graphic paper can significantly decrease the production costs of papermaking Filler preflocculation technology was proven capable of helping papermakers increase filler content by 3% to 5% while maintaining sheet properties Filler preflocculation technology has minimal impact on machine runnability Steam consumption reduced with increased ash. 22 PaperCon 2011 Page 642