2. Summary
From Tree to Pulp
From Pulp to Paper
Different kinds of paper
Paper characteristics
2 | [Wood, pulp and paper]
3. Summary
From Tree to Pulp
From Pulp to Paper
Different kinds of paper
Paper characteristics
3 | [Wood, pulp and paper]
4. Wood is use for ……..
World production by area - source FAO 2009
More info about the sustainability of the paper industry:
http://www.twosides.info/#page=Latest-5
4 | [Wood, pulp and paper]
5. Wood is used for….by continent
100%
Production by area by woodfuel sawnwood
90% continent - source FAO 2009 87%
wood based panels industrial roundwood
80%
pulp, paper & paperboard
70%
60% 57%
55%
49% 49%
50%
40% 38%
34%
30%
22%
19%
20% 17% 17%
14% 14% 16%
14% 14%
12%
10% 9%
10% 7% 7% 8% 8%
5% 6% 6%
3%
1% 0% 1%
0%
Europe Asia & Pacific Afrique Latin America & North America Western & Central Asia
Caribbean
5 | [Wood, pulp and paper]
6. Which part of a tree does the paper industry use ?
Wood left-overs,
wood shavings :
Construction wood : for pulp and
for carpentry, panelling
furniture or
construction
Bark :
for energy
Sawdust :
or compost
for panelling or energy
6 | [Wood, pulp and paper]
10. Pulp making : practically : Debarking
Cutting logs with
rotating saws
Logs rotated in
drum with water
Debarked logs
10 | [Wood, pulp and paper]
11. Pulp making : practically : Chipping
Chipper
Chip Screen
Chips Chips Chips!
11 | [Wood, pulp and paper]
12. From Tree to Pulp : Mechanical Pulp
2 Major processes :
Mechanical pulp
The wood is only mechanically
treated (grounded)
The yield is about 98%, rests
products (barks) are used as
fertilizer or for heating
1 ton of wood produces 980kg
mechanical pulp
All the lignin remains in the pulp
12 | [Wood, pulp and paper]
13. Stonegroundwood process
Debarking
Bark is used to produce energy (bleaching)
Pine Washing
logs
Grinding
water exit of the fibres
13 | [Wood, pulp and paper] rotating stone
14. From Tree to Pulp : Chemical Pulp
Chemical pulp
The wood is treated :
• mechanically (grounded),
• thermally (heated up in boiling water)
• chemically
All the lignin is removed from the
wood
The yield is about 50%:
With 1 ton of wood, we
produce about 500kg chemical pulp
14 | [Wood, pulp and paper]
15. Chemical pulp process
chips
cooking
debarking bleaching
washing
pine/birch sorting
Liqueur de cuisson
fraiche
Chemical recovery
Cooking liquor
Causticising
steam
evaporation
production of
electricity
15 | [Wood, pulp and paper]
17. Different types of pulp…..
Between Mechanical process & Chemical process, we have intermediate processes :
TMP and CTMP. These processes only remove part of the lignin, up to the level desired.
Trees Trees Trees Trees Secondary fibre
Logs Logs Logs Logs Deinking
Debarking Debarking Debarking Debarking Washing
Grinding Steaming Chemical pre- Chemical Recycled
softening cooking Pulp
Mechanical Grinding
Pulp Grinding Chemical
Thermo- Pulp
Mechanical Chemi -
Pulp Thermo -
Mechanical
Pulp
Wood Free Recycled
Wood Containing Papers
Papers Papers
Light Wood Containing Papers
17 | [Wood, pulp and paper]
18. Under the microscope…
Chemical pulp Mechanical pulp Recycled pulp
Pine Birch Birch
18 | [Wood, pulp and paper]
19. Different pulp for different kinds of paper
100 % chemical pulp 100% mechanical pulp
Strength is higher Less strength
Less stiffness Higher stiffness
Less bulk High bulk
Easy to bleach Lower brightness
Lower opacity High opacity
Smooth surface Rougher surface
Brightness stable with time Trend to yellowing
19 | [Wood, pulp and paper]
20. Bleaching of the pulp
Without bleaching, the pulp is brown
Therefore, depending on the level of brightness we want to achieve, we need to « bleach »
the pulp with chemicals. We can make it step by step with different chemicals :
2nd step 3rd step 4th step
20 | [Wood, pulp and paper]
21. Bleaching of the pulp
1
No Elemental
(Cl2) Chlorine
Free
2 No
(Cl2)
Total
And
Chlorine
Free
No
(ClO2)
21 | [Wood, pulp and paper]
22. Summary
From Tree to Pulp
From Pulp to Paper
Different kinds of paper
Paper characteristics
22 | [Wood, pulp and paper]
23. Integrated or not integrated……
Papermills do not always make their own pulp
they are so called “non integrated mills” (those who produce their own pulp are … integrated
mills); they received the pulp in units with a dryness of around 90%....
PULP PRODUCTION within SFPE
ALFELD
EHINGEN
GRATKORN
KIRKNIEMI
LANAKEN
STOCKSTADT
23 | [Wood, pulp and paper]
24. Just before the paper machine
Water
Hydrapulper Refining Cleaning & Screening
Softwood pulp
Dyes/Filler
Hardwood pulp
Waste Filter System
Recycled Water
24 | [Wood, pulp and paper]
26. Refining
Drawing of a refiner
Fibres are cut, frayed and hydrated Admission of
the pulp
discs
Feeding screw
Refiner discs
Outflow of Refining chamber
the
pulp
Slide
26 | [Wood, pulp and paper]
26
27. Refining
Fibres before refining fibers after refining
27 | [Wood, pulp and paper]
28. Cleaning and screening
Cleaned pulp
Pulp entry
Pulp entry
Rejected
material
Screened pulp
28 Rejected material
| [Wood, pulp and paper]
29. Just before the paper machine
Before the pulp is sent to the papermaking machine various additives are included.
Water
Papermaking uses a lot of water and this is why mills are built next to rivers.
A kilo of paper will use 100 litres of water.
The water systems are virtually closed where excess water is continuously recycled.
Colouring
Optical Brightening Agents are added that react with ultra violet light and give the paper a
blue whiteness.
Dyers are also added.
Binders
Both latex and starch are used to keep the fillers bound with the pulp. Starch also adds
stiffness.
Other additives
Anti bacterial, retention aids, pH buffers, …etc
Fillers
29 | [Wood, pulp and paper]
31. Paper machine
Up to 80 km/hour
Up to 10 meters wide,
430 meters long
Cost: a few hundreds
millions €
18 months to be built
31 | [Wood, pulp and paper]
32. Paper machine
The function of the paper machine is mainly to remove water
32 | [Wood, pulp and paper]
35. Forming the web
Fourdrinier former
Twin wire
Twin wire
hybrid former
Duo former
35 | [Wood, pulp and paper]
36. Press section
The water is removed
by pressure of the sheet in the nip
Press felts
water
water
paperweb
about 50% of the water is removed
in the press section
36 | [Wood, pulp and paper]
38. Pre - drying section
The water is removed by
evaporation
The moisture content of the
paper is around 5-8%
The basis paper is ready to be
coated (for coated papers) or
sized (for uncoated papers)
38 | [Wood, pulp and paper]
40. Fibrous support
Fibrous support + sizing = uncoated paper
Fibrous support + (sizing) + coating = coated paper
~ 0.1 mm
40 | [Wood, pulp and paper]
41. Size press
Absorption
Hydrodynamic pressure
Mechanical pressure
Split of the starch layer
A few g/m²/face is applied;
the layer is mainly made of starch
41 | [Wood, pulp and paper]
42. Post - drying section
The water is removed by
evaporation
The moisture content of the
paper is around 5-8%
The basis paper is ready to be
coated (for coated papers) or
calendered/rewinded for
uncoated papers
42 | [Wood, pulp and paper]
44. Why coating papers ?
uncoated paper light weight coated high weight coated
Print quality improves
44 | [Wood, pulp and paper]
45. Why coating papers ?
base paper light weight coated high weight coated
More and more coating
BRIGHTNESS
SMOOTHNESS
GLOSS
PRINTING QUALITY
Slide
45 | [Wood, pulp and paper]
45
46. What is the coating colour made of ?
What is coating ?
Le couchageis made of
Coating
Mineral pigments
Binders
Additives
Water (35-45%)
+ or – coating will lead to different kind of papers :
LWC, MWC, modern, classic
On-line or Off-line coating
Single, double, triple coated
46 | [Wood, pulp and paper]
47. How do we coat ? Blade coating
Base paper Coating
Blade
Coating tank
47 | [Wood, pulp and paper]
48. How do we coat ? Blade coating
Scanner Hot air dryer Infra red dryers Hot air dryer Scanner
Blade coating heads
48 | [Wood, pulp and paper]
50. Cross section of a coated paper
fibres
fillers coating
50 | [Wood, pulp and paper]
51. Surface of the coated paper
Satin? Gloss?
Silk? Matt?
Satimat? Demi-mat?
51 | [Wood, pulp and paper]
52. Satin or Mat ?
Satin Mat
150x
5000x
52 | [Wood, pulp and paper]
53. Classification of paper surfaces
Gloss Satin / Silk Matt
5000x
Gloss > 70 % 30 - 40 % <15%
Smoothness 1500 - 3000 sec 300 - 900 sec 50 - 200 sec
Marketing evaluation, no strict rule/norm
53 | [Wood, pulp and paper]
54. How do me make the surface ? Calendering
Pressure
Temperature
Moisture
MAT, BRILLANT, DEMI MAT, SILK, ...
Hardness of the rolls
Number of rolls
54 | [Wood, pulp and paper]
55. Supercalendering
Uncalendered
Steel Steel Paper
Soft Soft Blow rolls to
cool sheet and
Steel
prevent
Steel
wrinkling in nip
The soft
The soft rolls
rolls can Soft Soft
are usually
be of a
made of Reversing nip
cotton,
synthetic
paper or Soft Soft
covering
synthetic
covering
Steel Steel
Soft Soft
Steel Steel
Calendered
Soft Soft Paper
Bottom Bottom
driver roll driver roll
55 | [Wood, pulp and paper]
66. Summary
From Tree to Pulp
From Pulp to Paper
Different kinds of paper
Paper characteristics
66 | [Wood, pulp and paper]
67. Grammage (g/m²), Thickness (µm), Bulk (cm³/g)
Substance or basis weight : Thickness or Caliper :
weight in grams of 1 m² paper Distance between one face of the paper
and the other
Bulk (cm³/g) = Thickness (µm) / grammage (g/m²)
67 | [Wood, pulp and paper]
68. ISO-brightness (%) and CIE whiteness
ISO brightness is a measurement of reflected blue light off the paper surface.
This is expressed as a percentage in comparison with an ultimate reference.
The ISO standard only measures a portion of the reflected light.
The CIE whiteness measures the
reflected light of the whole spectrum.
For both measures, the higher the
value, the brighter or whiter the
paper is.
68 | [Wood, pulp and paper]
69. Opacity (%)
Opacity is related to the ability of light to
pass through paper.
The higher the percentage, the more
opaque the paper is.
Opacity isn't always determined by
thickness or weight; a thinner paper may
have more opacity than a thicker paper
if opacifying agents are used.
High Low
opacity opacity
Opacity (ISO 2471) can be defined as the ratio of reflectance
from a paper sheet backed by a perfect black and from a
sufficiently thick stack of identical sheets of paper.
69 | [Wood, pulp and paper]
70. Gloss (%)
Gloss is an optical phenomenon caused when evaluating the appearance of a surface.
The evaluation of gloss describes the capacity of a
surface to reflect directed light.
The measure can be made on the paper itself (paper gloss) or on a printed area (print
gloss). Gloss papers are generally the most calendered
and thus the thinnest.
Gloss
Please note we cannot compare gloss measures made paper
according to different norms (Tappi T480 & DIN 54502
are the most common).
Gloss paper => smooth => high gloss
Mat paper
Matt paper => rough => low gloss
70 | [Wood, pulp and paper]
71. Smoothness Bekk. (sec)
Known also as “roughness”
This method measures how long it takes for a certain amount of air to escape from
between the paper surface and a smooth metal disc.
The smoother the paper, the less openings there are between paper surface and metal
disc, so the longer it will take for the air to escape.
The higher the figure is, the rougher the surface is.
Mat paper Silk paper
71 | [Wood, pulp and paper]
72. Fiber orientation
The paper fibers naturally take up
alignment roughly parallel to the
direction of travel of the web on
the PM :
this becomes the grain direction or
the Machine Direction (MD).
the other direction is called Cross Direction (CD).
This influences the strength characteristics of the finished paper.
72 | [Wood, pulp and paper]
73. Grain direction
64
SG 64 x 45
Jumbo-reel
45
64
45 x 64
LG 45
• Long Grain: fibres // long side (LG) : 45 X 64
• Short Grain: fibres // short side (SG) : 64 x 45
The first dimension is by convention always the dimension cross the web
73 | [Wood, pulp and paper]
74. Questions ?
Will be happy to answer your technical questions :
Françoise Accou
+32 492.582.287
francoise.accou@sappi.com
74 | [Wood, pulp and paper]
![Wood, pulp and paper
1 | [Wood, pulp and paper]](https://image.slidesharecdn.com/basicsofwoodpulpandpaper-november2012-130130054018-phpapp01/85/Basics-of-wood-pulp-and-paper-november-2012-1-320.jpg)
![Summary
From Tree to Pulp
From Pulp to Paper
Different kinds of paper
Paper characteristics
2 | [Wood, pulp and paper]](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)