Increased Filler Content in Graphic Papers. K. M. Broadus, M. A. Ancona, W. Cheng, R. T. Gray, D. Castro

Transcription

1 Increased Filler Content in Graphic Papers K. M. Broadus, M. A. Ancona, W. Cheng, R. T. Gray, D. Castro 1

2 Abstract Purchased virgin fiber can cost 5 times more than filler. Nalco s technology delivers increased ash content while preserving the sheet s strength and optical properties. Pilot and commercial machine data will be presented. 2

3 Conclusions Successfully used to increase sheet ash content up to 5 units while maintaining sheet attributes in pilot and commercial machines. UCFS mill has utilized this technology consistently for over 1 year across all paper grades. Improved internal bond strength is a key deliverable. Resulted in equal or less dust in printing and converting trials, even at higher sheet ash levels. 3

4 Raw material cost reduction is a key business driver for every papermaker in today s market. Water / Energy 20% Fixed Costs 10% Raw Material Fiber 50% Commodity Chemicals 10% Specialty Chemicals 2% The cost of filler (PCC and GCC) is approximately 20% of the cost of purchased virgin fiber. 4

5 Challenges in higher filler usage Loss in sheet strength as filler level increases Dusting and picking in converting and printing operations 55 Sheet strength (tensile index Nm/g) % Filler in sheet 5

6 Technology Basis of Nalco s approach: Increase particle size of filler in order to minimize the interference with the fiber-fiber bonding strength network Controlled size distribution of filler flocs provides strength without compromising the formation and optical properties of the sheet Volume Percentage, % untreated PCC prefloc PCC particle size, um Designed for ash increases of 3-5 points Applicable for PCC, GCC or a blend of PCC/GCC Intended for UFS and CFS grades; demonstrated with a variety of furnish types Treated on-site; no holding time required before use Introduced with minimal adjustments to paper machine operations 6

7 Differentiation Controllable Method Well-defined particle size distribution of filler flocs PCR FillerTEK Technology TM PARETO TM Improved Stability Filler flocs exhibit improved shear stability ROI Maximize your profits by raising the limits Differentiation is achieved through a combined chemical and mechanical approach. Offering is strengthen by Nalco s expertise in wet-end operations and papermaking. 7

8 Impact of Bond Strength Pilot machine trial on EuroFEX gap former, 1000 m/min The ash level can be increased by 10 points without a loss in internal bond strength as measured by z-directional tensile. Eucalyptus /pine furnish, 80 gsm sheet produced in pilot trial at Innventia AB 8

9 Impact of on Opacity Pilot machine trial on EuroFEX gap former, 1000 m/min Opacity loss due to filler treatment can be recovered with a 2.5 point increase in ash content. Eucalyptus /pine furnish, 80 gsm sheet produced in pilot trial Innventia AB 9

10 Impact of on Formation Pilot machine trial on EuroFEX gap former, 1000 m/min Sheets showed a slight improvement in Kajaani formation relative to untreated PCC, at comparable FPR and FPAR values. Eucalyptus /pine furnish, 80 gsm sheet produced in pilot trial Innventia AB 10

11 Commercial Application Uncoated free sheet mill in Latin America: Produces 75 gsm copy paper and offset grades Top-former machine operating at 800 m/min; 400 TPD Using a blend of PCC/GCC Sheet ash: Historical ash level was 18%; currently at 23% Utilized continuously across all grades for over one year. Paper machine runnability is good: Production rate stable Sizing (ASA) usage steady, despite filler increase 11

12 Impact of Sheet Properties Commercial Account Results represent an average of 10 samples randomly selected from 10,000 sheets. Mill incorporated BCTMP in furnish for cost savings and bulk advantage. 12

13 Distribution of Filler in Z-Direction Commercial Sheets 30 Untreated PCC/GCC blend Treated PCC/GCC blend 25 Ash, % Relative Basis Weight, % z-direction ash profile remains similar at the higher level. Sheets were found to generate 47% less dust in a converting study of 10,000 sheets. 13

14 Print Trial at RIT Goss Sunday heat set offset press; 4 head (KCMY), 28,000 impressions Commercially produced 75 gsm text grade sheets: Untreated PCC at 25% ash Treated PCC at 25% and 29% sheet ash No runnability problems observed at higher sheet ash. Linting was monitored by tape pulls of printing blanket. Top side SM Essential Expertise for Water, Energy and Air Bottom side SEM images of tape pulls 14

15 Reduced Linting in Print Trial Tape pulls of printing blanket were analyzed for calcium (Ca) levels by EDS (energy dispersive x-ray spectroscopy). Conclusion: Linting decreases with Chemical technology. Ca counts Top Side 25% Filler 25% Prefloc 29% Prefloc Bottom Side B C M Y 25% Filler 25% Prefloc 29% Prefloc 75 gsm text grade 15