The Manufacture of Fine Papers

1
The Manufacture of Fine Papers

• Spring Semester 1999
• TEC 4562 Ink Paper Substrates

2
Introduction

• The ability of humans to supplement their speech
  with the written word is an indication of a high
  degree of civilization.
• From carvings on slabs of rock to paper, humans
  have been able to devise a form of communication
  that goes beyond speech.

3
The History of Paper

• What civilization invented paper?
• Ancient Egyptians?
• Moors or Arabs
• Persians?
• Aztecs?
• Japanese?
• Chinese?

4
Pre-Paper Media

• The following is a list of pre-paper media
  developed by early humans
• Wood
• Metal
• Stone
• Leaves
• Ceramics
• Bark
• Papyrus
• Parchment
• Cloth

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Egyptians and Papyrus

• The papyrus developed before 2,200 B.C. by the
  Egyptians was not considered true paper.
• The reason papyrus and the other materials did
  not qualify as paper was due to the way it is
  formed from a liquid suspension of individual
  fibers into a mat or sheet.
• It was made by slicking the plants stalk from
  end-to-end into very thin blades and then
  laminating them into something of a weave.
• It appears similar to cloth.

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The History of Paper

• Although papyrus is not structured like the
  writing or printing surfaces in use todayit
  became the Latin word for paper.
• Nearly 2,000 years later, the Chinese created the
  first true or practical form of paper.
• They did this by reducing raw material into
  individual fibers and then forming them into a
  mat or sheet.

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The Inventor of Paper

• It is widely accepted that Tsai Lun, a Chinese
  court official, invented paper in 105 AD.

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Tsai Luns Paper

• Mulberry Bark
• Hemp Waste
• Old Rags
• Fish Nets

9
The Wove Mold Process

• This process was devised by the Chinese
• Pulp was made by beating bark (Pulp Friction),
  which had been washed and boiled
• During the washing and boiling process, the pulp
  fibers were separated using smooth-edged stones
  and sticks.

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The Laid Mold

• Consisted of a flexible cover made of thin strips
  of bamboo held together with silk or some other
  similar thread
• It was placed on a wooden frame.
• The papermaker would hold the two together and
  dip them in a vat of water and fibers.

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The Laid Mold (continued)

• The papermaker would lift the mold and let the
  water drain away.
• This formed the sheet.
• The layer of wet paper and light bamboo were
  lifted from the wooden frame and placed on a
  smooth stone with the wet fiber mat facing down.
• The light bamboo matting was then rolled from the
  paper leaving a wrinkle-free sheet to be dried.
• The mold was reusable.

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Therefore,

• the Laid Mold was considered better than the Wove
  Mold

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Historical significance of paper...

• Early use as a symbol for money to burn over
  graves of the dead
• 175 A.D. - Paper replaced silk as a medium for
  writing.
• 610 A.D. the Japanese began to make paper
• 750 A.D. the battle fought between Muslims and
  Chinese at Samarkand in Turkestan (now part of
  Uzbekistan at formerly part of the Soviet Union)
  spurred the development of paper outside Chinas
  domain.

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• 875 A.D. - First known use of toilet paper.
• Late 900s - Playing cards invented.
• Mid 15th century - Johannes Gutenburgs invention
  of movable type spurred the production for paper
  necessary for the production of books.

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The Paper Renaissance- 17th to 19th Century
Europe

• France was the center of paper production...
• Exported papers to all of Europe
• It possessed the best papermakers and the finest
  equipment in the world.
• France also experienced internal struggle and
  unrest during the 17th century...
• This caused their papermakers to flee to England,
  Holland and America.
• The skilled French papermakers contributed to the
  English and Dutch paper manufacturers, thus,
  transforming them into the foremost paper
  manufacturers in Europe.

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Americas First Paper Mill

• Built in 1690 by William Rittenhouse
• Location Philadelphia
• Since that time, America has become the worlds
  largest producer of paper and pulp products

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Fibers for Papermaking

• Fibers are defined as ...tough threadlike
  substances capable of being spun or woven,
  whether they be natural (vegetable, mineral,
  animal) or man-made.
• In papermaking, animal fibers are not used at
  all, and mineral fibers are used only
  occasionally.
• Vegetable fibers (cellulose) wet easily in a
  water medium and will form a strong bond to each
  other when dried in contact.

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Four Types of Cellulose Fibers

• Seed Hair Fibers
• Cotton fibers
• Bast Fibers
• Flax plant
• Only 5 of the flax plant is usable for paper
  manufacturing
• Grass Fibers
• Wheat straw
• Bagasse fiber (extracted from sugar cane stalks)
• Esparto grass
• Kenaf plant
• Wood Fibers

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Seed Hair FibersCotton Plant

• Cotton fibers are very expensive.
• Used primarily for bank notes, high grade writing
  papers, mapsanything that requires exceptional
  strength and durability.

20
Bast Fibers

• Obtained from the flax plant.
• Located inside the stem.
• Only 5 usable for papermaking.
• Hemp and jute are other forms of bast fibers.
• Hemp has been used for cigarette and Bible papers.

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Bast Fibers (continued)

• Jute obtained from new burlap cuttings or other
  sources
• It is used for heavy duty shipping tags and heavy
  pattern boards.

22
Grass Fibers

• Wheat Straw
• Absorbs water readily.
• Was used during World War II in England due to a
  severe shortage of pulpwood.
• Bagasse fiber
• Made from crushed stalks of sugar cane.
• Used as a source of fuel for Sugar Mills.
• Esparto Plant
• Has very little strength and does not split into
  fibrils easily.
• Impractical for use in the United States because
  of the distance from the source of supply.

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Grass Fibers (continued)

• Kenaf plant
• Shows great potential for papermaking.
• May produce 5 to 7 times more pulp/acre than
  pine.
• Grows to maturity in 120 days compared to 20
  years for most trees.

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Wood Fibers

• 95 of all paper is made from wood fibers.
• Deciduous hardwood trees, e.g., Oak, Gum, Maple,
  Aspen, etc.
• Coniferous softwood trees, e.g., Pine, Spruce,
  Fir, etc. (the softwoods produce a stronger pulp).

25
Wood Procurement

• 39 of the available forests in the United States
  are in the South.
• Private citizens own 3 quarters of land.
• Paper industry uses specially designed equipment
  to harvest prepare crops of trees
• Power chain saws
• Skidders-forest tractors are used for opening
  sections of land.
• Specially designed combines.
• Mechanized tree shears.
• Cranes, clamp trucks, truck dumpers.
• Slashers saws.
• Debarking drums.

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Pulping

• The objective of pulping is to separate the wood
  into individual fibers.
• Three broad classifications of pulping methods
• Mechanical (groundwood)
• Chemical
• Combination (chemi-mechanical)

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Mechnical Pulping Processes

• Stone Groundwood
• Mechanical process used to rip fibers from the
  logs
• Slurry of pulp formed from the grounded mix.
• Can be made from either hardwood or softwood.
• Refiner-Mechanical Pulping
• Wood chips are pumped into rotating disks causing
  internal friction that generates heat.
• The heat from the refiner softens lignin.
• Thermo-Mechanical Pulping
• Chemi-Mechanical Pulp

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To Make Groundwood Pulp...

• The bark is removed from the logs.
• Then, the cut logs are forced by hydraulic or
  steam pressure against a revolving grinding stone
  in the presence of water.
• This treatment converts the wood into a pulp
  consisting of minute particles of both fibrous
  and nonfibrous portions of wood.
• The nonfibrous materials deteriorate when left
  for some time in contact with air.
• Therefore, paper made from this kind of pulp
  lacks permanency.

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Groundwood Pulp

• This type of pulp is not as strong as chemical
  pulp.
• Groundwood pulp has to be mixed with other pulps,
  e.g., Newsprintcontains 80 groundwood pulp and
  20 chemical pulp.
• It is highly suitable for products such as
  wallpaper, paper towels, or lightweight catalog
  papers.
• It is unexcelled in its ability to produce papers
  with high opacity, smoothness and ink receptivity.

30
Thermo-Mechanical Pulp

• To make TMP, wood chips or sawdust are first
  softened by steam and then subjected, under
  pressure, to the defibering action of a a
  disk-type refiner.
• This causes the fibers to completely separate
  from each other and suffer less damage than those
  produced by the conventional groundwood pulp
  process.
• TMP is cleaner and stronger when compared with
  groundwood pulp.

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Chemical Pulp

• Chemicals are used to reduce wood chips into
  fibers.
• This process separates each fiber from its
  bonding materiallignin.
• The adhesive qualities of lignin holds cellulose
  fibers together.

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Bleaching

• The purpose of bleaching is to remove stains
  caused by lignin.
• Major bleaching agents
• chlorine, sodium hypochlorite, hydrogen peroxide,
  chlorine-dioxide, and oxygen.
• Chlorine gas is one of the different bleaching
  systems that are used to remove lignin that
  remains in the pulp.
• Chlorine gas is passed into the pulp-water
  mixture.
• The gas reacts with whatever lignin that is left
  and becomes chlorinated.
• The chlorinated lignin is then removed when
  treated with the caustic soda NaOH (Sodium
  Hypochlorite)

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Fourdrinier Paper Making Machine

• Nicolas Louis Robert invented the papermaking
  machine in 1798.
• Sealy Fourdrinier and Robert improved the
  original design of the papermaking machine to
  produce paper with a felt side and a wire side.
• The paper is formed at the wet end of the
  machineafter the pulp-water mixture has been
  refined.
• Fillers
• Coloring material
• Sizing

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The Headbox

• The headbox spreads pulp and water mix evenly
  over the moving wire.
• The pulp-water mixture containing the added
  fibers, coloring material and size is diluted
  with water to make slurry containing ½ to 1
  of cellulose fibers.
• The headbox must maintain the uniform delivery of
  dispersion of fibers across the width of the
  machine.

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The Fourdrinier Wire

• The fourdrinier wire causes the forming of paper
  at the wet end of the machine.
• It is the section of the papermaking machine made
  up of a fine woven screen to let water drain away
  causing the pulp to remain to form a thin mat.
• Suction boxes remove water as the mat moves along
  the wire.
• Synthetic plastic fiber wires are used in modern
  papermaking machines.
• When the mat had left this stage of production it
  contains 75 water.

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Presses

• During this stage of production, the mat enters
  wet rollers carried by felt blankets to reduce
  the amount of water to 60 - 65.
• It is during this stage that the thin mat or
  paper begins to form a web or long ribbon.
• The paper continues through press rolls and felt
  blankets to remove water.

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Dryers

• Steam heated cylinders dry paper to 5 moisture.

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Size Presses

• Size press applies 10 starch solution to both
  sides of paper.

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Dryers

• Second dryer unit removes moisture applied to
  sheet in size press.

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Calender-Reel

• Polished rollers iron and control thickness of
  sheet. Reel winds paper on mandrel.

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Winder

• Winder unwinds paper from mandrel, passes sheet
  across slitter to trim edges and cut paper to
  final width.

42
Twin Wire Machines

• This method of papermaking was developed to
  improve the efficiency of the fourdrinier design.
• Two vertical sides restrain the furnish to permit
  the extraction of water from both sides of the
  paper.
• Increase machine speeds and reduction in drying.

43
Cylinder Machine

• This type of machine is designed for making
  extremely heavyweight paper and/or multi-ply
  products used in the manufacture of corrugated
  containers, folding cartons, and solid fiber
  boxes.
• All layers for multi-ply products can be
  manufactured with all layers formed in a single
  continuous operation.
• Two types of cylinder vats contraflow and direct
  flow.

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Paper (handout)

• 1. The Chinese are given credit for inventing the
  technique of papermaking.
• 2. To make a continuous supply of wood, the basic
  raw material for making paper, paper companies
  operate tree farms.
• 3. Pulp fibers are obtained from, woody fibrous
  materials, and reclaimed products are made from
  these materials.
• 4. Wood pulp sources are divided between softwood
  (coniferous) and hardwood (deciduous).

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Paper (handout) continued

• 5. All paper fibers are made of a compound called
  cellulose.
• 6. Lignin serves as a binder and support for the
  cellulose fibers of woody plants.
• 7. Groundwood pulp process uses almost all of the
  substance in wood to make paper.
• 8. The manufacturer of chemical pulp uses
  chemical action to dissolve some of the woods
  substances to make higher quality paper.

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Paper (handout) continued

• 9. The chemical-mechanical pulp method combines
  mechanical and cooking separation processes.
• 10. Opacity refers to the amount of light that
  can be seen through a sheet of paper.
• 11. In all three pulping methods, washing is used
  to remove all traces of chemicals and dirt from
  wood fibers.
• 12. True. Groundwood pulp is often referred to as
  mechnical pulp because it has been reduced to
  fibers by a mechanical grinding process.

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Paper (handout) continued

• 13. The pulp selected for bleaching is treated
  with chlorine and similar chemical solutions to
  whiten the paper fibers.
• 14. The primary purpose of adding fillers to the
  pulp is to strengthen its properties.
• 15. Sizing is used to helpl make paper less
  absorbent and more water repellent, so it will
  not allow ink to spread.
• 16. Dyes and pigments are added to pulp during
  washing to give paper color.

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Paper (handout) continued

• 17. The forming of paper starts at the wet end of
  the papermaking machine. Then processed pulp,
  which is 99 water, flows rapidly over an apron
  the width of the machine onto a moving mesh wire
  screen.
• 18. Where the paper touches the screen, it shows
  a mesh pattern. This is called the wire side of
  the paper.

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Paper (handout) continued
19. Identify the water content and machine
sections of a typical papermaking machine
operation in the mill.

• A. 99.0 - 99.5
• B. 75
• C. 60 - 65

• D. 5
• E. 35
• F. 4.7 - 5.5

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Paper Making Machine

• G. Headbox
• H. Fourdrinier
• I. Presses
• J. Dryers

• K. Size
• L. Dryers
• M. Calender-Reel
• N. Winder Press

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Paper (handout) continued

• 20. As the paper starts to form, the pulp passes
  under a dandy roll to produce a surface finish on
  the paper. The roll is made of mesh wire.
• 21. The paper begins to form into a web, or long
  ribbon as it passes through the papermaking
  machine.
• 22. The ribbon of paper continues through press
  rolls and felt blankets, which remove more water.

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Paper (handout) continued

• 23. The side of the paper that is in contact with
  the felt blanket is called the felt side of the
  paper.
• 24. Calender rolls are made of smooth iron to
  polish the paper and give it a very smooth
  finish.
• 25. Sheet-fed offset paper must have more
  strength than other printer processes because of
  the tackier ink.
• 26. The basis weights of paper generally used for
  web offset range from about 20 - 80 pound.

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Paper (handout) continued

• 27. Joining the ends of two rolls of paper is
  referred to as splicing.
• 28. There are eight paper properties which must
  be considered for each job
• Grain
• Finish
• Pick Resistance
• Brightness and Basis weight
• Flatness
• Ink setting and sizing
• Moisture absorbency and resistance
• Opacity

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• 29. Fibers tend to align themselves in the paper
  as it passes through the machine. This alignment
  of fiber is referred to as the grain of the
  paper.
• 30. Tear strength in paper increases with
  increased fiber strength.
• 31. The term finish refers to any action
  performed to the surface of the sheet of printing
  paper that affects its surface.
• 32. Coated papers are exceptionally smooth, since
  they are subjected to an additional smoothing
  process.