All slides for April 15 - June 24, 2014

Biomaterial Science（Schedule）
#

Date

1

4/15

History of papermaking
Pulps – Beating and fiber properties

Content

Bio-Material Science

2

4/22

3

5/9, Fri Pulps – Additives and functions

Toshiharu Enomae

4

5/13

Papermaking processes & interfiber bonding

Professor, PhD, Paper Device and Eco-friendly materials

5

5/20

Paper– Structural properties

6

5/27

Paper– Surface properties

7

6/3

Polysaccharide chemistry by Assoc Prof Akiko Nakagawa

8

6/10

Paper–Wetting and absorption properties

9

6/17

Paper– Mechanical and optical properties

10

6/24

Recent trend of paper science and technology

EG60411

2G103, 10:10-11:25, Tuesday

Lecture information and contact

Biomaterial and Biomaterial Science Homepage of “Biomaterial Science (T.

 What biomaterial is

Enomae)” http://www.enomae.com/→ Handouts in lecture(講義資料)
 E-mail address→ t@enomae.com
for any questions and visit to laboratory(Bio-Agr. Bldg. 生農C209 or E201)“Paper” －Definition
 “A thin, flat material obtained by sheet-forming and drying fibers especially ofplants”

Materials constituting components and thestructure of organisms processed to provide
properties required for the use such as:
Wood, paper,
paper, cellophane, rubber,
rubber,leather, polylactic acidpolylactic acid What biomaterial science is

Science and technology for providing highperformance to biomaterials

Scope of Paper Science Colloid Sci（Fiber dispersion system）+ Applied Paper Sci

Colloid Science
Fiber dispersion

Silviculture・ Wood Chem・
Biotechnol. Pulping
Digestion

Pulp

 “A thin, flat material made from crushedwood or cloth used especially for writing
and printing on and in packaging”- Cambridge Dict.
 Plant fibers, especially wood-sourced, as a

ForestChip

Applied Paper Science
Printing, Packaging

Calendering

Bleaching
CoatingDrying

Press

Wire

Inlet

raw material of paper are called “a pulp”

Biomaterial Science by Toshiharu Enomae

1All slides for April 15 - June 24, 2014

Who has affected you most?
 “Who has affected you most in your life so far?”

was voted in an internet site.
 Jesus Christ received the second largest

numbers of votes
 Ts’ai Lun（蔡倫）received
the largest.
(A) Without paper, printing technology would nothave developed, nor would wealthy life today beguaranteed.

Origin of paper Ts’ai Lun is traditionallyregarded as the inventor of
paper. Exactly, however, heinvented the composition for
paper along with thepapermaking in A.D. 105.
 The fibrous materials used inthose day were bark, hemp,
silk, and fishing net.

Origin of paper

MoscowEngland The world oldest paper

found in that is
estimated to be between
179 and 142 BC (earlyWestern Han 漢朝).
 It was used as a map,
where mountains,
Fangmatan（放馬灘）paper
waterways and roads
are drawn.

USA

蔡倫

Westward and eastward from China

Nuremberg 1390
Fabriano
1276

Samarkand

BaghdadTs’ai Lun 105

Improvement of paper Japan 610

Spread of papermaking technology

History of papermaking tech. -Materials

History of papermaking tech. -Materials

 Hemp （Cannabis大麻・ Linen亜麻） Leaves, of Treang tree to make

Cannabis has been used for
cloth and fishing net in China
and Japan. Linen in Europe.
Hemp Rags Recycling of cloth woven originally from
hemp. Cotton from the age of Industrial
Revolution
 Bast (skin) fibers, such as Paper Mulberryetc. for Japanese paper“Sastra”
 Wood, capable of producing on alarge scale Kenaf

A kind of hemp promoted forforestry preservation, but not
accepted any more.

 Plastics, synthesized paper frompolypropylene called “Yupo”

Biomaterial Science by Toshiharu Enomae

Treang tree

Sastra2

All slides for April 15 - June 24, 2014

Origin of Printing technology
Gutenberg (1395? –1468)
invented a printing press in around
1445.
The invention consisted of mass-producing movable type; oil-based ink from linseed oil; and a wooden printing press similar to
the agricultural screw presses
and allowed the mass production of
printed books and was economically
viable for printers and readers alike.

42-line Bible (42B) Gutenberg printed andpublished 180 copies of
42-line Bible.
 The start of the age of theJohannes Gutenberg

printed book in the West Relationship with paper Increased paper demand Development of mass production of paper Use of wood as a papermaking material
 Invention of paper machine to produce

Movable type“continuous paper”.

History of papermaking tech. – Machine
The Greatest Inventions of the Past 2000 Years
Edited by John Brockman and published on Jan 12, 2000
John Brockman, a novelist of USA, asked “What is the mostimportant invention in the past two thousand years? and Why?”
to famous.
“Reading glasses” and “eraser” were unexpectedly proposed.



Many people including Dr. Philip Anderson, a Nobel prize
winner, chose “printing technology” because it promoted
knowledge occupied by privileged people to the public.
Another physical scientist chose “watch” for quantification oftime passage that was dependent on one’s sense so far.
“Heliocentric theory”, “mathematics”, “differential and integral
calculus”, “democracy”, and “religion” were also supported.


See http://www.edge.org/documents/Invention.html

Mechanical pulping－Groundwood pulpGP or SGW ([Stone] Groundwood Pulp)
Keller invented ground wood pulp in 1844

Biomaterial Science by Toshiharu Enomae

1670 Hollander beater invented [Holland]
1719 Reaumur submitted his invention - paper can be madefrom wasp hives- to the Academy [France]
1798 Louis-Nicolas Robert invented manufacture of continuous
paper [France]
1844 Keller invented ground wood pulp [Germany]
1851 Burgess [USA] and Watts [England]invented soda pulping
to make wood pulp.
1856 Healey received a patent of corrugated [England]
1856 Tilghman invented the sulfite pulping [USA]1879 Dahl invented Kraft pulping [Germany]
1950 Hardwood pulping initiated[Japan]
1968 Thermo-Mechanical Pulping (TMP) Developed[Sweden]
1977 Quinone-added pulping invented [Japan]

Old printed material in Japan
In 764, Emperor Koken
had holy texts (無垢浄光陀羅尼経) printed on paper
one million copies forpeace of Japan, containedin one million wooden
miniatures of a three story
tower, and laid out in theten great temples like
Horyu-temple and Todaitemple.

3

All slides for April 15 - June 24, 2014

The world oldest printed material

The world oldest printed material

In 1966, printed holy
texts was discovered in
the Buddha tower of
Bukkoku-temple (仏国寺)
of Keishu, Shinra (新羅慶州), currelty Korea(韓国).
This tower is known tohave been built in 751.

Paper with holy texts (華厳経)
written in 755, Silla era (新羅)was analyzed.

世界最古の印刷物

 755年に新羅時代の華厳経が書かれた紙

Paper Industry of Japan

Bankruptcy of Lehman Brothers Great East Japan Earthquake
Production amount, million ton

35
30

From 2004

25
‒7.8%

20
15

Paper board
Paper

10
‒17.8%
50Year

Biomaterial Science by Toshiharu Enomae

4All slides for April 15 - June 24, 2014

Production of paper and paperboard
120

100

Production , million ton

How to make paper  From “wood”
China
(A2)
USA
Japan
(A3)
Germany
Sweden
Korea
CanadaFinland
BrazilIndonesia
India
Thailand

80

60

40

20

0

ForestChip1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

Wood tissue－cells of beech tree

Waste(A4)
paper

Wood
(thinned out)

Pulp

Paper

Axial parenchyma cell
Bright-field

Polarized light

Component of
hardwood tissue
Vessel20%
Wood fiber

60％

Axial
10％
parenchyma cell
Radial10％
parenchyma cell

parenchyma cells

Wood tissue－structure of cell wall
S3 layer(Secondary cell wall - 3rd layer )Cellulose microfibril(indicated by parallel lines)

S2 layer

0.1 mmKind of pulp
 Pulp Fibers mainly consisting of cellulose
extracted from plant such as wood bymechanical or chemical treatment
 Mechanical pulp [MP]S1 layerBast fibers

Fibers extracted from wood by crushing Chemical pulp [CP]Primary wall
Middle lamella

Fibers extracted from wood by dissolving lignin

 Deinked pulp [DIP] (recycled pulp)
Fibers extracted from waste paper by removing ink

Structure of plant cell wall and axial direction of cellulose microfibrils

Biomaterial Science by Toshiharu Enomae

5All slides for April 15 - June 24, 2014

Wood composition－Major 3 components

Chemical pulp－Fiber geometry
Softwood pulp fiber

Chemicalcomponent

Hardwood pulp fiber Copy paper

consists ofpulp fibers

(B)

wood

Approx. ratio (%)

Hardwood

Softwood Hardwood

Cellulose

Cellulose

45

45

Hemicellulose

25

30

Lignin25

20

 Observe pulps

Form of pulp

45 %Hemicellulose
30 %OthersTerpenoid
Resin acid
Fatty acidetc.

Lignin2-8Bleached
kraft pulp
40 %

20 %

10 %
2%

Others5%

Change of Compositionby kraft pulping

Disintegration - Separation into individual fibers
Slush pulp
Pulp suspension withconcentrations of approx.
1-4% Lap pulp
Pulp Formed and folded bywet machine. Called “Drylap” when dried

Dry lap pulpDry lap pulp

Dispersed in water ( (D) pulp)

Bale pulp
A bunch of pulp sheets
compressed and boundwith a wireTransported (C) pulp

Standard disintegrator (defibrator)

Waste paper in yard

Pulp is put in water in steel
container with ca. 3.4 L capacity
Stirred with a propeller mixer at
3000 min-1（rpm）
Latency of MP should be
removed at high temperature（Latent=hidden）
Pulp
ChemicalDry Water Revolmass volume utions
30 g
2.0 L 30,000

Mechanical

60 g

2.7 L

Biomaterial Science by Toshiharu Enomae

60,0006All slides for April 15 - June 24, 2014

Waste paper and pulp

Belt conveyer

Disintegration in industry (pulper)

Disintegration in industry (Drum pulper)

Drum pulper

Floatation
 Deinking
Postflowtation

Disperser

Centrifugal

 Bleaching
Peroxide
tower

Floatation (flowtator)

Post-flowtator

Biomaterial Science by Toshiharu Enomae

7All slides for April 15 - June 24, 2014

Beating (refining)

Beating (refining)

Post-disintegration process Process where shear stress is applied
to water-containing fibers resulting infibrillation (formation of small
filaments or fibers) on the surface
and concentrically loose structure

Beating achieves large bonded area
between fibers and thus higher paper
strength.

Q. Why can this breaking process increase paper strength?

Difference between disintegration and beating Disintegration is a process toseparate fibers bonded orentangled, keeping fiber
characteristics
 Beating is a process to treat

mechanically individual fibers,changing fiber characteristics

Beater－PFI mill (beating)Beater－Refiner(refining)Processed by refiner

Rotor

In

Out

Motor
Blade
Disk plate
StatorOut

Rotor
Pulp slurry flow Stator

Beating － mechanism

Effect of blades on pulp fibers during beating

https://www.youtube.com/watch?v=b17d6ssw8f4

Biomaterial Science by Toshiharu Enomae

8All slides for April 15 - June 24, 2014

Refining－movie－refiner

Beating－change of fibers－external fibrillation
External fibrillation
Internal fibrillation

Scanning Electron Micrographs of freeze-dried
softwood pulp fibers after beating

Beating－change of fibers－internal fibrillation

Beating－change of paper structure

External fibrillation

Internal fibrillation＝Concentric loosening(Lamellar separation)
Connection of small
pores formed by lignin
removalLamellar separation offiber cell wall by beating

Unbeaten (left) and beaten (right) softwood pulp sheets
Q. How did fibers and sheets change by beating?

Evaluation of fiber properties
 Freeness (Drainability)
 Specific surface area
 Fiber length distribution
 Distinguishment by staining
 Fiber coarseness Curl index

Evaluation of Freeness
Canadian standard
freeness（mLCSF）



One L of pulp
suspension at 0.3%
and 20 ºC is pored andthe volume (mL) of
water drained from theside pipe is measured.
Q. Does CSF increase or
decrease by beating?

Biomaterial Science by Toshiharu Enomae

9All slides for April 15 - June 24, 2014

Evaluation of Freeness

Water Retention Value (WRV)Canadian standard freenessUnbeaten pulp ca. 650 mL CSF
Beaten pulp ca. 400 mL CSF
Reasons why freenessby(E)
beating are
 More fines (small pieces of fibers)
 Fibrillation
make paths between fibers in a pulp
mat thin, winding, and long.

Nitrogen adsorption methodLangmuir model

Mw : Mass of pulp after centrifugation
Md : Mass of the pulp after oven drying

WRV(%) =100×(Mw－Md)/Md
Q. Calculate WRVs to 2
decimals in percentage.

All the adsorption sites areequivalent and the surface ishomogenous.
 Monolayer coverage No interactions between
adsorbate molecules on adjacentsites

Nitrogen adsorption method
Nitrogen gas
(N2)

Paper
specimen
Liquid nitrogen(Coolant)

Biomaterial Science by Toshiharu Enomae

WRV, %
102

Bleached hardwood

101

TMP

139

CTMP (hardwood)122

After cent.(g) Oven dried(g) CTMP (50% HW + 50% SW)
Unbleached sulphite
0.61
0.23

Pulp

SBKP beaten

124
104

SBKP unbeaten 0.59

0.28

Recycled pulp

159

HBKP beaten
0.54
HBKP unbeaten 0.45

0.22
0.24

Non-wood pulp

204

Never-dried Kraft pulp

114

Nitrogen adsorption methodSampleBleached softwood

Langmuir model (cont’d)The fractional coverage of the surface θchanges at the adsorption rate
proportional to gas pressure p and thenumber of empty sites N(1-θ).
The desorption rate proportional to Nθ.

Nitrogenmolecule

Material surface

Adsorption
site

Specific surface area (SSA)
DryingmethodSampleUnbleached Spruce KP
Bleached Spruce KP
Solvent
Spruce α-cellulose
exchange
Spruce GP
Birch KP
Evaporation Unbonded pulp fibers
at 105 °C
Paper
KP=kraft pulp, GP=ground wood pulp

BET SSA, m2/g
230
185
185
25
129
1.2
0.5 ̶ 1.0

10All slides for April 15 - June 24, 2014

Length and width of fibers

Fiber length and width distribution

Softwood tracheid
Hardwood fiber
Hardwood vessel

Fiber tester, ABB(L&W), Sweden

1 mm

Fiber length and width distribution

Fiber length and width distribution

CCD camera
0.5 mm
Water

Water

Example of captured image

Fiber length and width distribution

Mean fiber length
Copy paper
MeasurementlShredderUnshredded

Projected area A
Width =
True length L
Shape factor =(Linearity)

Projected length ℓTrue length L

Biomaterial Science by Toshiharu Enomae

Shredded
5 mm wide each

Dispersed
in water11

All slides for April 15 - June 24, 2014

Effect of beating on paper propertiesComparison in fiber length between shredded
and unshuredded copy papers
40

Coefficient LSA decreases as

Shredded

Ratio (%)

 Specific Surface Area on Light Scattering30

1.76 mm20

Unshredded

fiber bonding area
increases.
 Interfiber bondingarea can beevaluated by SSA.

2.06 mm10 Beating

0
0

1

2

3

4

5

6

7

Fiber length (mm)increasedinterfiber
bonding area.

Light scattering coefficient,, m2/kg

Mean fiber length

BET surface area, m2/kg

Effect of beating on paper properties

Effect of beating on paper properties Beating increased Wet Fiber Flexibility

 Beating increased Density and Modulus ofWet fiber flexibility, 1/Nm2

Bending strengthof single wet fibers
was measured for
determination of
WFF.
 SR = SchopperRiegler method for
determination ofdrainabilityLinear relationshipbetween density
and MOE
regardless ofbeating degree
F=kx

2x

Elastic modulus, GPa

Elasticity (MOE)(WFF)

k; spring
constant
= MOE

x
F
2F

Beating degree, SR-number

Density, kg/m3

Effect of beating on paper properties

Stock preparation－ additives

 Beating increased Stretch at Break (SAB) to Paper quality control

Size (sizing agent) - water repellency
Filler - brightness and opacity
 Strength agent – dry or wet strength Dye – optical brightening agent (OBA)with as well, butleveled off.

Low beating degree

High beating degree

Stretch at break, %certain degree
 SAB increased Paper manufacturing control

Retention aid – ex. aluminum sulfate –fines, fillers, and size retained more Antiseptic (preservative)Density, kg/m3

Biomaterial Science by Toshiharu Enomae

12All slides for April 15 - June 24, 2014

Additives－size and filler
Acidic paper
Size (sizing
agent)

Additives－size and filler

Non-acidic paper

Rosin (abietic acid)
AKD

Rosin（Abietic acid) Alkyl ketene dimer （AKD）,
Alkenyl succinic anhydride（ASA）
Aluminum sulfate Cationic polymer such as(alum),Polyamine-amide
deteriorates paper epichlorohydrin (PAE)
Clay, Titan dioxide, Calcium carbonate, Titan
TalkdioxideRetention
aid
Filler

pH at
4.5～5.5
papermaking+[ C (CH 2)4 C NH (CH 2)2 N (CH 2)2 NH ]nO

7.5～8.5(7 or slightly greater)

O

ASA
PAE

OH

Q. Why is calcium carbonate not used for acidic paper?

Additives – deterioration of acidic paper
Aluminum sulfate deteriorates paper.
Al２(SO4)3 + 2H2O → 2Al(OH)2+ + 2H+ + 3SO42CH2OH
O
OH

O

CH2OH
O
OH

+ H2O

OH

OH
CH2OH
H
O
OH
HO
OH

OH

O

Acidic paper
Strength Cationic polyacrylamide(C-PAM)
resin
CH2CH n CH2CH

O

CH2OH
O OH, HOH

Additives－size and filler (2)Acid hydrolysis↓
Deteriorationof paper

Papermaking – Additives - movie

C=O

C=O

NH2

O

O

Non-acidic paper
Cationic starch
CH2OH
O
OH
CH3
O
CH2-CH2-N+-CH3

CH3

CH2-CH2-N+-CH3

CH3

CH3

Cationic polyacrylamide

Cationic starch

Papermaking－approach section
Pressurized screen Head box

Wire (Fourdrinier )Centrifugal cleaner

白水 waterWhite

Secondary screen
Secondary cleaner

Fanpump Wire
pit
Inlet

Beaten pulp
Broke
Additives

Machine
chest

Paper
product
Broke

RecycleBiomaterial Science by Toshiharu Enomae

Markets
Consumers
Waste
paper

13

All slides for April 15 - June 24, 2014

Papermaking - wire section
Twin-wire machine

Fourdrinier machine

Papermaking – (wet) press section
 A wet web is pressed at high pressure

Felt

Cylinder machine

Web
CylinderQ. What is a merit of
Cylinder machine?

between large rolls to squeeze out excesswater.
 Water transfers to felts that sandwich thewet web.
 Pressing increases
density and wet web
strength.
 The common numberof nips is 3 or 4.
Kodak Historical Collection #003 (1986)

Papermaking – (wet) press section

Papermaking – dryer section
 Steam-heated cylinders dry the paper withcanvases.

 Free water evaporates, between fibers first , inside

fibers second, and between fibrils last .

 At less than 9 % moisture content, bonding water

evaporates, forming interfiber bonds.

Paper
Canvas (felt)

Drying cylinder
for felt
DryingcylinderPaper

Canvas (felt)
Vietnam Paper Corporation (2014)

Papermaking – calender section

Papermaking – calender section

 A number of rolls press the passing paper.
 They make the paper surface extra smooth and glossy

with friction, and provide a higher density and more
uniform thickness
プライバシー保護のため、この画像の自動ダウンロードをブロックしました。

Supercalender
Soft nip calender

Biomaterial Science by Toshiharu Enomae

14All slides for April 15 - June 24, 2014

Types of chemical bondPapermaking – calendering effect Ionic bond = a chemical bond in which two ions are joined

Paper gloss, %Linear pressure at nip:Thickness decrease ratio, % Gloss improvement and compression of paper

together because one has a positive charge and the other anegative charge
 Covalent bond = a chemical bond in which two atoms share
one or more pairs of electrons that hold them together (ca.
500 kJ/mol) Hydrogen bond = a weak connection that is formed between
an atom of hydrogen (= a gas) and an atom of anothersubstance such as oxygen or nitrogen (= a gas) （10～40
kJ/mol）
 Van der Waals forces = the relatively weak attractive forcesthat act on neutral atoms and molecules and that arise
because of the electric polarization induced in each of theparticles by the presence of other particles
 Dipolar bond (coordination bond) Metallic bondBasepaper

Coat layer

Number of passed nips

Number of passed nips

 The number of nips is occasionally more than 10.

Q. Why is it as many as 10 although only 3 or 4 for wet press?

Inter-fiber bondInter-fiber bondEffect of water on interfiber bond formation

Cellulose surface
Fiber

H-O-H

L µm

H-O-H

Fiber

d µm


The attractive force iscalled Campbell force.

Inter-fiber bondEvidence of hydrogen bond








Interfiber approach and hydrogen bondformation due to water evaporation

H-O-H

Q. Suppose twocrossing flat fibers witha square , length L on aside at the crossing
point. As they dry andthe interfiber distance dcomes to 1 mm, Howmuch contraction stressdevelops between thetwo fibers?



H-O-H



Cellulose surface

Loose hydrogen bond mediated by water

Firm hydrogen bond with a water monolayer Direct hydrogen bondInter-fiber bond
 Effect of cell wall thickness on wet fiber flexibility

When paper mass was measured after allowing tostand in deuterium water (D2O) vapor until
saturation, 0.5 to 2.0 % of hydrogen of all thehydroxyl groups was not replaced with deuterium.
This ratio corresponds to the percentage ofhydrogen bonded hydroxyl groups.
Energy required for tensile breakage was calculated.
19 kJ/mol (equivalent to hydrogen bond energy)
Strength decreased with acetylation of carboxylgroupsCell-OH → Cell-O-C-CH3
O

Biomaterial Science by Toshiharu Enomae

15

All slides for April 15 - June 24, 2014

Inter-fiber bondForming (Wire section) － Moisture content
HeadboxSlice Effect of fiber flexibility on Relative Bonded Area

Bonding ratio, %Cell wall thickness, µm
4.7 µm
8.8 µmSize press

Couch rollWiresectionFiber flexibility, 1/Nm2

Pulp
1%
Moiture99 ％PresssectionCalendersectionDryer section

20 %

40 %

95 %

80 ％

60 ％

5％

Pigment coating

Pigment coating

Pigment
BinderWater
Dispersion / Mixture

Blade coater etc.

Pigment coating

Coated paper surface Scanning Electron Micrograph

Basepaper
surfaceCoatingsurfaceBiomaterial Science by Toshiharu Enomae

To increase smoothness, brightness,
opacity, and gloss, and control liquid
penetration

16

All slides for April 15 - June 24, 2014

Drying and processing – movie

Paper properties –Fundamental and applied properties
 Conditioning Structure Surface chemistry Liquid absorption
 Mechanical properties Optical properties

 23 ºC

50% RH (Relative Humidity)

Paper properties depend on
humidity, but less on temperature
although temperature differenceby more than 10 ºC changes ex.
tensile strength significantly.

Paper structure – basic properties
 Grammage (g/m2)

Mass (g) per square meter at 23 ºC and 50％RH
Grammage（（oven-dry basis）） is based on theconstant mass attained when kept at 105 ºC Thickness (mm)Single sheet thickness, distance between twoparallel planes holding a sheet at 100 kPa
 Bulking thickness, thickness per sheet,calculated from that of 10 superimposed sheets Includes surface roughness (dents)


Biomaterial Science by Toshiharu Enomae

Conditioning and test atmosphere Hysteresis

Moisture content (%)

Conditioning and test atmosphere Dry paper to half

50 humidity% r.h. (%)
Relative

the equilibrium
moisture content
and back to 50%
RH for testing Moisture content
is affected by
crystallinity

Paper structure – basic properties
Q. Which is higher, single sheet thickness or
bulking thickness?
 Density

Mass per unit volume in g/cm3 calculated fromgrammage divided by thickness

17All slides for April 15 - June 24, 2014

Paper structure – basic properties Density（grammage/thickness） affected by grammage!?

Paper structure – Why is the thickness
different between the two methods?

Apparent thickness, µm

140Filter paper side

120
100
80

Laboratory sheet

60

Sheets prepared fromsoftwood bleached kraft
pulp beaten moderately

40
20

Micrometer
thickness

0
0

20

40

60

80

Metal plate side100

Mercury B
thickness

Grammage, g/m2

Paper structure – Factors affecting density

Paper structure – Factors affecting density
 Wet press and calendering

0.8

0.8

0.7

0.7

Density, g/cm 3

Density g/cm 3

 Beating and filler loading

0.6
0.5
0.4

Beating rev. (PFI mill）

Calcium carbonate addition

Paper structure-Scanning electron microscope(1)

0.6
0.5
0.4

Wet press

Paper structure-Scanning electron microscope(2)100 µmCopy paper

Newspaper

Biomaterial Science by Toshiharu Enomae

Calendering- linear pressure

100 µmJapanese paper

Tissue paper

18

All slides for April 15 - June 24, 2014

Paper structure– Smoothness
紙の構造-表面形状測定

Paper structure – Smoothness

Surface profile can be measured in 2D or 3D.
Stylus, light beam, electron beam, or probe Air leak method Air flow rate through a gap between

paper surface and smooth metal plate Surface profile (Microscopy) Surface shape measured using

profilometry such as stylus profilometry,
confocal optical microscope.
 Several ways of expressing surface
roughnessOken smoothness, s

Ra =

1 l
y dy
l ∫0

Root mean squared roughness

z

y
dy

Paper structure –Smoothness of coated paper
450
400
350
300
250
200
150
100
50
0

Centerline average roughness(arithmetic average)

RMS =

1 l 2
y dy
l ∫0

l

Paper structure - FormationFormation
[] Unevenness sensed visually when
white light is transmitted through paper – STD or
CV of optical density
Transmitted light I 0  I1 I2 …
log Mass
B1 B2 …
 In 
[]
Distribution of
local mass Bn –STD or CV ofPaper I0 I0
local mass
Irradiating light
STD=Standard deviation, CV= coefficient of variation

After calendering
Basepaper
Before calendering

0

5

10

15

20

Latex content, pph

Paper structure - Formation
Time until dehydration (s)Transmitted lightimages of softwood
pulp sheets Formation becomes
(F)
worse
by cationicpolymer addition
and increased time
until dehydration
 Cationic polymers
increases fiber
retention.

10

Interaction- between paper and water (liquid)

120

Cationic polymer
P:Added
N:Nonadded



Wetting Contact angle
 Surface energy Sizing degree
 Liquid penetration Swelling


HN10

HN120

HP10

HP120

Biomaterial Science by Toshiharu Enomae

19All slides for April 15 - June 24, 2014

Surface chemistry - Contact angleSurface chemistry - Contact angle

Contact angle (θ)
 The angle made by the solid and liquid surfaces Supposed that the area including

when a liquid droplet is placed on a solid
surface.
 When 0º< θ < 90º, “wetted” and when θ>90º
γL“unwetted”.

microscopic structure is r times larger
than the apparent one, Wenzel’s contact angleγ

Young equationLθ When the contact angle

is constant, horizontal
components of forces
are balanced.

 On a rough surface,140

Wet-press: 90 g/m2, 0.70 MPa130180
r=1 の場合

150

見かけの接触角θw

when θw ＜ θ at θ ＜90º, easily-wetted
surfaces become
more easily-wetted.
But, when θw ＞ θ at
θ ＞ 90º, hardlywetted surfaces
become more hardlywetted.

γsContact angle of paper - Beating effectcos θ w = r cos θ

Wenzel’s equation

θγiγi － γs ＋ γL cos θ ＝0

Surface chemistry - Contact angleθwcosθ w = r cosθγsγiContact angle, °Contact angle on a rough solid surface

r=1.2の場合
r=2 の場合

120

Hardly-wetted

90

120
110
100

5000 rev beating
10000 rev beating
20000 rev beating

90

60

Easily-wetted

30

80
0

0
0

30

60

90

120

150

180

200

400

600

Contact time, s

真の接触角θ

Beating and smoothness
Oken smoothness, s

Hardwood kraft pulp sheet Surfacessmoothed bybeating
became easilywetted.

20
15
10
5
0

20000 Rev
10000 Rev
5000 Rev

Grammage and wet press pressure

Biomaterial Science by Toshiharu Enomae

Surface chemistry - Contact angle

On composite surfaces

Cassie's law

 The effective contact angle θC is dependent on

the areal ratio of each component.
 is stated ascosθ C = Q1 cosθ1 + Q2 cos θ 2, where θ1 is the contact
angle for component 1 withareal fraction Q1 and θ2 isθ
the contact angle forcomponent 2 with areal
fraction Q2 (Q1 + Q2 = 1). Component 1 Component 2

20

All slides for April 15 - June 24, 2014

Surface chemistry - Contact angle

Surface chemistry - Contact angle
Q. What is the contact angle θc of sized paper?
 Sizing agent need not cover the whole surfaceof fibers for repelling water. If a sizing agent
covers 5% of the whole surface, what is thecontact angle θ ?
 Assume that θ is 0˚ for unsized fibers and 120˚
for the covering size.
θc(G) × cos 0º +
 cosθc = 0.95
(H) × cos 120º
0.05
Paper
cosθc = 0.95 –(I)0.025 = 0.925(O) ºθc = 92.1

Size

(J)
θc = 22.3º

Paper
Size

Surface chemistry - Contact angle


Q2. What is the contact angle θc of sized paper?
 Half the volume of paper is air. If 50% of
paper surface is air, what is the θc ?
 Assume that θc of a true surface of sized
paper is 22.3˚ and θ of air is 180˚.
(K)(K)
 cosθc = 0.5×cos
22.3º + 0.5×cos
180º(K)(L) + (K)cosθc = 0.5×0.925
0.5× (M)1θc(N)= 0.155

Liquid absorption theory - Capillary model

Comparison in Water absorptionForce developing arounda meniscus of a liquid ina capillary (pipe)
Steady flow in a pipe

γ

πPr 4
Q=
8ηl
Parchmentθ

F=2πrγcosθ
F

2πr
S=πr2

θ
r

l: Capillary lengthr: Capillary radius
η: Liquid viscosity
Q: Volumetric flow rate

Wood-containing paper

P=F/S=2γcosθ/r

P

γcosθ

(Hagen-Poiseulle equation)“wood-containing” means “made from mechanical pulp”

Liquid absorption theory - Capillary model

Water absorption rate - How to measure

Q. Substitute the relation represented in the figure into
the H-P equation and develop the Lucas-Washburn equation.



H-P equation

2γ cos θrdVdlQ== π(Q)
r2
dt
dt
Substitute

πPr 4
Q=
8ηl


P=

dl

Bristow’s apparatus

A liquid supply head filled witha liquid of volume V scans
paper at various speeds v.

dt

2dl
dV = πr(P)rrγ cos θ ⋅ t2η

Biomaterial Science by Toshiharu Enomae

15 mm (w) Contact time

t=b/v

V
Scan speed
Slid width

Lucas-Washburn equationl=

1 mm (b)
Paper
moves

v

 Transfer Vol

Liquid volume
Slit width
Trace lengthvb

Vt=V/(wL)
V
w
L

21

All slides for April 15 - June 24, 2014

Calculate transferred volume per unit area Vt
L

w

Vt

Scan speed
Slid widthvb Transfer Vol Vt=/V (wL)

Liquid volume V
Slit widthw
Trace length L

Automatic Scanning Absorptometer（Spiral-scan Bristow’s apparatus）

Vt = Vr + K a T − TwFor oil, Tw = 0.
Then,

Vt = Vr +(Q)
Ka T

Oil A

Vt

Oil B

Water
Ka
Vr

Bristow’s plot of kraft paper

Water absorption rate - How to measureFor water,

Vr Roughness index
T Contact time
Tw Wetting delay
Ka Absorption coeff.

V Contact time t = b/v



Tw
T

Contact time, s

Water absorption rate of ink jet paper -ASA

To meniscus
detector

40
No.1

 Scanning speed changes stepwise during
measurement

Water supply
head

1 mm
5 mm
Infrared sensor
Glass capillary

Volume of INK transferred, mL/m2

Water absorption rate – Water and oil
Transferred liquid volume, ml/m2

Water absorption rate – How to measure

No.2
No.3

30

20
・インキが転移しなかった部分のデー
タ点、明らかに誤ったデータ点を省略
してプロットした図・No.1と2は、ほぼ同じ傾向のインキ

100Meniscus

0

5

10

15

Square root of contact time, (ms)1/2

Step motor

ASA

Mechanical properties –Tensile strength

Mechanical properties –Tensile strength

Load-elongation curve
Method 15 mm in width
 100 mm in span 10 mm/min elong speed
 Tensile index I

Plastic region

Load, N

Limit ofelasticity

ࡵ ൌ

∆F
∆Li
Elongation, mm

compression
 Breakage of inter-

fiber bonds
 Breakage of fibers

:





Strain at break εT
 εT ൌ

∆L

 Extension of micro-: 
 Extension of curl

Load, NF∆Elongation, mm
Elastic region

Modulus of elasticity E*

 Elastic elongation of fibers∆: 
∆ Elastic elongation of fiber

 E*ൌ

Biomaterial Science by Toshiharu Enomae

network

Compressive
force

Fiber

Microcompression

22All slides for April 15 - June 24, 2014

Anisotropy–Tensile strength

Anisotropy–Tensile strength
1212Unbeaten kraft paper (89.4 g/m2)
Copy paper (64.4 g/m2)

10

MD

8
Unbeaten kraft

6

Load, kgf

Load, kgf

10

CD

Copy paper

48Light-weight coated paper(64.9 g/m2)
Newsprint paper(46.4 g/m2)

MD

Light-weight coated paper
Newsprint paper

CD

6
4
2

2
0

0
0

1

2

3

4

5

6

7

8

0

1

2

3

4

5

6

7

8

Elongation, %Elongation, %Q. Why does light-weight coated paper elongate greatly?

Mechanical properties – Stiffness (Bending) stiffness

S represents the degree to which

paper resists bending

S=EI

S=Mr

E is Young’s modulus
I is area moment of

M is bending
momentMechanical properties – Stiffnessr (m)inertiar is radius ofcurvature

M (mN⋅m)M



Taber Stiffness15˚ Bending moment

when a test piece
38mm wide is bent
to 15˚ and load
length 50 mm
 The unit is mN⋅m

Taber tester

Mechanical properties – Folding endurance

Prospective future with
Paper devices andEco-friendly materials

 Folding endurance
 logarithm number ofdouble folds at 120˚on both sides thatare required tomake a test piecebreak Longer fibers
tend to show
120˚
higher values.

1kgf

120˚
MIT tester

Biomaterial Science by Toshiharu Enomae

Toshiharu Enomae
Professor
Faculty of Life and Environmental Sciences
University of Tsukuba , JAPAN23

All slides for April 15 - June 24, 2014

Development of Paper-based medical
check-up sensor and technology ofliquid transport in a micro-channel

 Paper device（Paper in future）• Paper electronics• Paper–based medical check-up sensor• Energy supply device• Paper-based bioassay system

Kento Maejima
Yinchao Xu
Toshiharu Enomae Paper cultural heritage（Paper in past）• Conservation Science Fundamental papermaking technology（Paper at present）• Paper coating, paper physics and chemistry, etc.
Yinchao Xu

Paper substrate
Doctor in hospital• Capillary force due to porous structure

Data

Diagnosis
Patient at home

• Liquid transport
designed channel

・Fewer patients in hospital for fewer days
→ Appropriate medical service by hospitalLab-on-paper as a medical check-up sensor

Affordable and simple device is required

Microchannel Fabrication
Advantage of paper and improvement

IJ printing• Cheap, disposable, portable, and flexible• Cotton linter pulp→ almost no impurities• Porous → micro-channel to transport liquid• Smaller pore size → Less ink bleeding
Beating,
revolutions-PFI millDensity,
g/cm3

1

10000

0.568

2

20000

0.622

3

30000

0.641

#

UV irradiation

Paper
Top

Top

Back

Back

Perspective

Top
Back

3 mm

Citterio, D. et al., Proc. MicroTAS 2011, 2099-2101

193

Biomaterial Science by Toshiharu Enomae

Microchannel was successfully fabricated24All slides for April 15 - June 24, 2014

Fabrication Processes of electrodes
Electrodes printed with PEDOT:PSS

Sample solution• 0.5 M KCl• 2 mM K3[Fe(CN)6]• 15 U/mL HRP• Glucose Conc.
(0-4.16 mM)

Prepared paper
Micro-channel printed
with UV-curable ink

BMP (binder&mediator)
PEDOT:PSS (electrode)Lab-on-Paper was successfully fabricated

1.2
y = 0.160 x + 0.203
R² = 0.979

0.9
0.6

n=3

0.3

Glucose + O2 
Gluconic acid + H+ + eGlucose concentration
quantified successfully

0
0
1
2
3
4
5
Glucose Concentration [mmol]

195

4 mm
Micro-channel
printed

(4 μL)

Effect of beating

9

0.12

Volume/ Grammage (μL/g/m2)

30 mm

Ink jet printerDimatix DMP-2831
Fuji Film, JAPAN

10000 Rev

0.1
0.08 2000 Rev

Effect of calendering

875000 Rev

6

Volume (μL)

EnzymeCurrent (t=10 s) [mA]

BMP printed
Enzyme (Glucose oxidase) printed

Potentiostat

Dispense

0.06

5
4
3

0.04

Uncalendered
0.5 MPa
1 MPa
3 MPa

2
0.02
1
0

0
0

200

400

600

800

1000

0

50

Time (s)Ink• Styrene-acrylate copolymer, CP-900, Harima Chemical, JAPAN• Neutral red (dye staff)

Lucas-Washburn’sequation: V ∝ rp

Laboratory of Paper Devices and Eco-friendly Materials
Prof. Toshiharu Enomae, University of Tsukuba

Beatingrp

Calendering rp

100
Time (s)rpWatertransport rp

150

200

Irreversible
Reversible

Paper-made Electric Power Generator

Conversion of vibrationenergy of paper toelectric energy

Moving-electrodeMoving-electrode

Electrode (Copper)
Paper

Electret (Teflon)
Electrode (Copper)～

Electret
Static-electrodeVibration

Biomaterial Science by Toshiharu EnomaeiiRApplication to:
Voice-activated posters

25All slides for April 15 - June 24, 2014

Bacterial culture system using paper
substrate and ink jet printing
Tithimanan Srimongkon

Ink jet printer dispenses

Toshiharu Enomae

Stack of Petri dishes fordifferent conditions!!

• constant number of cells,• same patterns, and• a few environments in
one medium.

48 hours after printing

Agar sheet medium

Dot of E. coli colony

Agar sheet medium

Agar medium
Printing
Liquid agar medium

Hydrophilic
Hydrophobic

0 hr

12 hrs

24 hrs48 hrs36 hrs• Bacteria grew
successfully.
• Agar maintained
moisture for 24 hObservation

Bacteria

Bacteria printing

Biomaterial Science by Toshiharu Enomae

26

All slides for April 15 - June 24, 2014

Influence of saltwater immersion onproperties of flood-damaged paper
Tunchira Bunyaphiphat
Akiko Nakagawa-Izumi
Toshiharu Enomae

Mold grows and• Characters cannot beread due to color• Bad smell• Health hazard
Flood-damaged paper and books • Artistic value lost
To inhibit mold growth
WashingDryingRestoration… Speedy action is difficult!

Immersion in saltwater

was proposed.

International alliances
Tsukuba
Vocational college of paper
technology and electro mechanics

0%

2.0%

3.0%

• As NaCl
concentration
increases, bacteria
grew less (top), and• fibers swelled less(right).

3.5%
Pure water
NaCl aq. sol.

Vietnam Forestry University

Asian Institute ofTechnology, Thailand

Chulalongkorn
University, Thailand

Zhejiang
University of
Science andTechnology , China

University of Technical
Education Ho Chi Minh City
Royal University ofPhnom Penh, Cambodia
Center for Pulp andPaper, Indonesia

Thank you for attention.

Biomaterial Science by Toshiharu Enomae

27