Papermaking The process of going from Pulp to Paper

1. PapermakingThe process of going from Pulp to Paper

2. Objectives Of Papermaking • Good Formation • Physical and Optical Properties • High Capacity (tons paper/day)

3. PapermakingWet to Dry • Stock Preparation (Wet-end) • Refining, Screens, Cleaners, Chemical Additives • Papermachine • Headbox, Forming Section, Press Section, Dryers, Size Press, Paper Reel • Dry End • Coating, Calendaring, Rewinding, Packaging

5. Refining • Purpose of Refining • Collapse fibers to improve bonding • Fibrillates (shreds fibers) to improve bonding

6. RefiningIncreased Bonding

7. Pressure Screens • Remove large contaminants • Plastics • Metals • Rocks

8. Centrifugal Cleaners • Use centrifugal force to remove contaminants • Removes particles that are lighter or heavier than pulp • Plastics • Dirt

9. Chemical Paper Additives • Acids and Bases • Control pH • Sizing Agents • Rosin, waxes, AKD • Used for paper grades requiring water repellency or controlled rate of water absorption • Dry Strength Additives • Starch and other polymers • Used to improve strength and stiffness of paper • Wet Strength Additives • Polymers that crosslink to fiber surfaces • Used for paper grades such as toweling

10. Chemical Paper Additives • Fillers • Clay, talc, TiO2 (titanium dioxide) • Improves optical and surface properties for printing grade papers • Retention Aids • Polymers that improve retention of fiber fines and fillers • Defoamers • Improve water drainage and sheet formation • Slimicides • Controls slime growth and other microorganisms in papermachine whitewater

11. Papermachine • Headbox and Forming Section • Press Section • Dryer Section

12. Papermachine BasicsFourdrinier Machine • Headbox • Distribute fibers onto wire • Forming Section • Form sheet and remove water • Press Section • Remove more water and improve smoothness and bonding • Dryer Section • Dry paper using steam • Paper Reel - Roll up paper

13. Headbox and Forming Section Headbox Gap former (also called twin wire former) can remove water from both sides of the sheet.

14. Headbox and Forming Section Secondary headbox Used to make linerboard like what is on the outside of fruit boxes. Primary headbox would be brown pulp and secondary bleached pulp.

15. Mechanical Water RemovalHydrofoil • As the wire passes over the foil the pressure underneath the wire is less than on top and water is forced through the wet web. water

16. Press Section • Remove more water from sheet before drying • It can smooth surface of sheet and reduce bulk (make a thinner sheet).

17. Papermachine Water Loop(Basis: 1 ton bone dry pulp) 1.49 ton 339 gal 0.5% fiber 20% fiber 40% fiber 92% fiber Forming Section Press Section Dryer Section Fiber 1 ton 1 ton 1 ton 1 ton Water 4 ton 950 gal 1.5 ton 360 gal 0.09 ton 21 gal 199 ton 47,400 gal 195 ton 46,450 gal 2.5 ton 590 gal Recycle

18. Papermachine Energy Consumption(Basis: 1 ton air dry pulp) Electricity 100 kWh Stock Prep Forming & Pressing Dryer Section 140 kWh 90 kWh Steam 0.7 GJ 0.3 GJ 3.4 GJ Drying accounts for approximately 66% of total energy consumption.

19. Dryer Section • Water removed by evaporation using steam heated cylinders.

20. Size Press • Puts surface coating of a sizing agent on a sheet • Usually starch • Decreases water and air permeability and increases paper strength.

21. Calendaring • Means to “press with a roll” • Smoothes surface of paper sheet

22. Paper ReelThe End of the Line

23. Rewinder • Cut and roll paper to customer needs.

24. Pigment Coating To dryer • Fine filler particles mixed with binders put on surface of paper • Improves sheet surface for printing Knife or Air Paper Sheet Coating