creping. tissue machine creping
TRANSCRIPT
•Introduction
•Definition of Creping
•Types of Creping
•Types of Crepe
Creping
•Hardware Geometry
•Theoretical Model
•Process Variables
•Sheet Properties
•Coatings
Yankee Dryer
Wet Press Reel Doctor Blade
Crepe Structure Formed
Creping
Yankee Dryer
UncrepedSheet
CrepedSheet
Blade Holder
Creping Changes the Sheet
From
To
Hood
Yankee Dryer
Former
Felt
Reel
Creping Blade
Typical Dry-Crepe Machine
•Introduction
•Theoretical Model - Macroscopic Model
- Microscopic Model
•Hardware Geometry
•Process Variables
•Sheet Properties
•Coatings
Creping
Yankee Dryer
CoatingAdhesive Uncreped
Sheet
CrepedSheet
GrindAngle
Blade Holder
BladeWearAngle
PocketAngle
BladeExtension
YANKEEDRYER
Mechanism of Creping
YANKEE DRYER
Microfold (Primary Crepe)
Macrofolds (Secondary Crepe)
Microfold (Primary Crepe)
Macrofold (Secondary Crepe)
Yankee Dryer
Doctor Blade
Creping Analogy
6 m 90 E
Pocket Angle
MG SHEET CREPING BLADE
95 km/hr
Failure Mechanisms in Compression
P
Shear Zone
Lateral Supports
P (a) Shear-slip-plane
mode (brittle) (b) Bending mode (c) Bulging mode
(internal rupture)
P P
P
Lateral Supports
We want this kind of failure
P
Crepe Wavelength
Crepe Amplitude
Folding Radius
Crepe Structure Measurement
Creped Sheet
100X Actual Size
•Introduction
•Theoretical Model
•Hardware Geometry
•Angle Definition
•Inter-Relationships
•Measuring Blade Angles
•Process Variables
•Sheet Properties
•Coatings
Creping
Creping Geometry Yankee Tangent Line
Yankee Tangent
Creping Blade
Yankee Dryer
Creping Geometry Blade Wear Angle
Yankee Tangent
Creping Blade
Yankee Dryer
Blade Wear
Angle
Creping Geometry Blade Grind Angle
Yankee Dryer
Blade Grind Angle
Yankee Tangent
Creping Blade
Creping Geometry Creping Pocket Angle
Blade
Yankee Dryer
Creping Pocket
Yankee Tangent
Creping
POCKET = 90 - WEAR+ GRIND
Creping Geometry Creping Angle Summary
Yankee Dryer
Blade Grind Angle
Yankee Tangent
Creping Blade
Creping Geometry Sheet Take-Off Angle
Creped Sheet
Creping Blade
Yankee Dryer
Yankee Tangent
Sheet Take-Off Angle
SHEET-TO-BLADE + TAKE-OFF = POCKET
Creping Geometry Sheet to Blade Angle
Sheet-to- Blade Angle
Creping Blade
Yankee Dryer
Yankee Tangent
Creped Sheet
SHEET-TO-BLADE + TAKE-OFF = POCKET
Effect of Creping Pocket Angle Crepe Amplitude vs Creping Pocket Angle
PRIMARY
SECONDARY
Creping Pocket Angle, degrees
0.6
0.5
0.4
70
0.3
0.1
0
0.2
75 80 85 90 65
Yankee Dryer CREPING
Yankee Tangent
Creping Blade
Cre
pe A
mplit
ude
s,
mm
Reflective Wear Angle Gauge
Flashlight Angle Finder
Sighting Tube
Micarta Block
Doctor Blade
Base
Magnet
Typical Dry Creping Geometry 12 - 24
2.6 kN/m (15 pli)
Blade Wear Angle
Loading Pressure
O
0 - 15
82 - 88
52 - 68
12 - 30
12 - 19 mm
0.65- 1.25 mm
Blade Grind Angle
Creping Pocket Angle
Sheet Take-Off Angle
Sheet-To-Blade Angle
Blade Extension
Blade Thickness
O
O
O
O
Creping Mechanism Effect of Pocket Angle
Pocket Angle < 80
Pocket Angle > 80
Primary Crepe Only
Primary & Secondary Crepe
Creping Mechanism TISSUE CROSS SECTIONS
Creping Pocket Angle = 65
Creping Pocket Angle = 80
O
O
•Introduction
•Theoretical Model
•Hardware Geometry
•Process Variables •Pocket Angle
•Adhesion
•Basis Weight
•Uncreped Sheet Properties
•Sheet Properties
•Coatings
Creping
Creping Mechanism Effect of Adhesion Level
LOW ADHESION
HIGH ADHESION
Fine, Uniform Crepe
Coarse, Skippy Crepe
Creping Mechanism TISSUE CROSS SECTIONS
Dryer Adhesion = 2.3 gram per inch
Dryer Adhesion = 12.2 gram per inch
Effect of Adhesion on Crepe Amplitude
2 4 14 6 8 10 12 16
Sheet-To-Dryer Adhesion (g/in)
0.13
0.15
0.11
0.09
0.07
0.05
Creping Mechanism
UNCREPED
SECTIONS
High Adhesion, Pocket < 80
High Adhesion, Pocket > 80
PRIMARY
CREPE
ONLY
PRIMARY &
SECONDARY
CREPING
Low Adhesion, Pocket < 80
#1
#2
#3
o
o
o
Effect of Basis Wt on Crepe Amplitude
8 10 20
Basis Weight (gsm)
0.11
0.09
0.07
0.05
0.03 12 14 16 18
•Introduction
•Theoretical Model
•Hardware Geometry
•Process Variables
•Sheet Properties
•Creping Moisture
•Strength
•Debonding
•Crepe ratio
•Coatings
Creping
200X
Sheet Debonding
0 4 8 12 16 20 0
20
40
60
80
100
Debonding In Creping Process
Effect of Adhesion and Blade Geometry
Adhesion To Dryer (g/in)
80 Pocket
70 Pocket
60 Pocket
o
o
o
50 60 70 80 90 100
Dryer Adhesion vs Sheet Dryness
Sheet Dryness, %
FT 94
TAPPI
Strength - Softness Curve Facial Tissue
Invariant Tensile Strength (g/ 3” sheet)
0
2
4
6
8
10
12
0 200 400 600 800 1,000 1,200 1,400
QA
L S
oftn
ess
Strength - Softness Curve Facial Panel Softness
Invariant Tensile Strength (g/3”)
0 400 800 1,200 1,600 2,000 0
2
4
6
8
10
12
Historical Line
Closed Pocket Angle
Open Pocket Angle
Very Open Pocket
8
600
6
4
2
0 1,000 1,400 1,800 2,200
Overall Strength (g)
10
So
ftn
ess
Facial Tissue Brand / Structural Comparison
Sheet Debonding vs. Stiffness
% Debonding/ Length
Sensory Panel Stiffness
15.0 Marcal 7.4
30.0 6.0
5.0
5.8
4.5
3.6
30.0
37.5
45.0
55.0
Secondary Fiber Kleenex
Virgin Fiber Kleenex
Regular Puffs
Kleenex Softique
New Puffs
Panel Stiffness
Reel Doctor Blade
Crepe Ratio
Crepe Ratio = V 2 / V1
where:
V 2 is Reel surface speed V 1 is Yankee Dryer surface speed
Bulk Development in Creped Wadding
1 2 3 4 5
0.2
0.4
0.6
0.8
0
Crepe Ratio
90 Pocket
80 Pocket
O
O
O
Debonding In Creping
Weak Points KOTEX ® TYPE WADDING
Closed Pocket, High Adhesion
Uniformly Debonded, No Weak Points KLEENEX ® FACIAL WADDING
Open Pocket, High Adhesion
•Introduction
•Theoretical Model
•Hardware Geometry
•Process Variables
•Sheet Properties
•Coatings
•Definition
•Inorganic Coatings
•Organic Coatings
•Application Systems
Creping
Title of Chart
Title of Chart
"Advanced" Coatings "Natural" Coatings
Organic From
Fibers
Organic From
Fibers
Inorganic
Salts
Inorganic
Salts
Embedded
Fibers Embedded
Fibers
Synthetic
Additives
Title of Chart
Inorganic Salts
•100 ppm Calcium needed to form good coatings
•Some must harden water to achieve
•More than 600 ppm will cause excessive scaling elsewhere
Organic From
Fibers
Embedded
Fibers
Inorganic
Salts
Creping Adhesive References
Poly-(aminoamides) Winslow.Spicer 1972:Giles.Espy 1975:Oliver 1980:Schoreer et al.1982: Soerens 1985.1987 : Obokata.Takizawa 1990
Polyamides Lazorisak et al. 1977: Pomplu.Grube 1984 : Marzullo 1987: Chen et al. 1989: Soerens 1991
Polyamines Lazorisak et al. 1977: Latimer.Stevens 1983: Soerens 1991
Polyvinyl Alcohol Bates 1975: Grube.Ries 1981: Pomplun.Grube 1984: Soerens 1985 : Pippen 1987; Soerens 1987: Chen et al. 1989:Soerens 1991
Polyvinyl acetate & copolymers
Grossman1977: Lazorisak et al.1977: Grube.Ries 1981: Pomplun.Grube1984 : Pippen1987: Chen et al 1989
Polyethers & copolymers polycrylic acid
Pomplu.Grube 1984: Soerens 1991 : Lazorisak et al. 1977:
Animal glue Fuxelius 1967: Sanford.Sisson 1967: Lazorisak et al. 1977: Oliver 1980
Starch Fuxelis 1967: Salvucci. Yannos 1974: Oliver 1980
Cellulose derivatives Grossman 1977: Marzullo 1987
Title of Chart
Absorption Diffusion
Mechanical Interlocking
Weak Boundary
Layers
Chemical Bonding
Acid-Based Interactions
Electrostatic Attractions
Components of Adhesion
Strong adhesion between materials
is governed by two interactions:
• Intimate molecular contact closer than 9
angstroms (0.0000000009 meters). This is a
necessary condition.
•Maximum attractive force with minimum
potential energy. This is a sufficient condition.
(Chung 1991)
Force
Cast Iron
Adhesive
Cotton Cloth
Peel Speed = 30 cm/min
Peel Adhesion Test
Adhesion Values
0.0 0.5 2.0 1.0 1.5 2.5 3.0 3.5 4.0
90.0
80.0
70.0
60.0
50.0
40.0
30.0
20.0
10.0
0.0
Concentration (% actives)
Sample 1 Sample 2 Sample 3 Sample 4 Sample 5
Ave
rag
e P
ee
l F
orc
e (
g/2
5m
m)
Typical Tensile Stress
Strain
Low Modulus
Weak
Tough
Strain
High Modulus
Strong
Tough
Brittle
Coating Requirements
• Must form uniform films
• Provide stable adhesion
• Be stable
• Have some re-wettability
• Have controllable hardness
Synthetic Additives
Organics from
Fibers
Inorganic
Salts
Embedded
Fibers
Thermoplastic
(rewettable)
Thermoset
(cross-linking)
Release
Kymene
• Good attraction to fibers (cationic)
•Strength increases with heating
•Crosslinking polymer
•Limited wettability
•Provides good dryer protection
•Minimum addition rate for dryer
protection is 0.35 kg/ton
PVA
• Nonionic (compatible with kymene)
• Good film former
• High cohesive strength
• Rewettable
• Different grades available
•% Hydrolysis
•Molecular Weight
• Typical application amounts: 0.3-2.5 kg/ton
based on tissue grade
Peel Adhesion
PVA / KYMENE MIXTURES
10 0 20 60 30 40 50 100 70 80 90 600
800
700
1,000
900
1,100
1,200
% Polyvinyl Alcohol (balance kymene)
Releases
• Modify coating
•Provide lubrication for doctor blade
•Examples
Quaternary Amines - Quaker 2008
Emulsified Oils - Cynol, Mulrex, Houghton
Polyglycol Esters - Hercules M-1336
•Quat. Amines and Esters provide less release
action
•Oils are powerful releases and difficult to
control to correct amount
What we spray on the dryer -
Water Polymer A Polymer B Release
Inorganic Salts
What is actually in the coating -
Cellulose fiber Ash?
Polymer A Polymer B
Inorganic Salts Release Water
Dryer Coating Composition (In order of % of mixture)
Coating Application System
Recirculation Line
Chemicals
Water
Coating Application System
Hard Water
Chemicals
Mixer Spray Boom & Nozzles Filters (2)
Yankee Surface Pressure
Gauges
Booster Pump
Variable Speed Chemical Metering Pumps (Gear)
Mass Flowmeters
In-line
VS VS VS
FIC FIC FIC
Check
Valves
Metering Pumps
Advantages
Disadvantages
• Inexpensive
•Uneven flow, possible hammering in lines
•Pulsation dampers needed
•More Accurate
•Infinite speed adjustment
• Expensive
•Reduces nozzle plugging from:
•Water source •Undissolved PVA •Bacteria "slugs"
•Should be placed close to application
•Progressively finer screens as
you move down steam
Filters
•Must be safe and convenient for operator
•Should have:
•Gauge cocks to isolate tips •Separate cross bars w/individual bodies for each tip •Removable booms
•Typical set-up: 15 cm apart, 12-20 cm away from yankee, 700 900 kPa supply pressure
•K-C uses Spraying Systems Unijet® nozzles
•Spray angles range from 65 - 110
•Flowrates range from .025 - .100 gpm
•Nozzle part number tells flowrate and spray angle at 275 kPa
Example:
80 01
80 Spray Angle .100 gpm Flowrate
65 0050
65 Spray angle .050 gpm Flowrate
Spray Nozzles
O O
O
O
"W"
"H"
Spray Nozzle Geometry
O/2 O/2
20 40 60 100 80 120 140 160 200 180
50
60
70
40
100
80
90
Spraying Systems Uni Jet Nozzles
8001
6501
6501
650025
Nozzle Pressure (PSI)
650025
Spraying Systems Vee Jet Nozzles
0.3
0.2
0.1
0 20 40 60 100 80 120 140 160 200 180
650025 650033
650050
650067
6501
0
Pressure (PSI)
50
Volumetric Distribution of Spray Nozzle For A New Nozzle
0 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 1
10
20
30
40
Spray Pattern
Spray Pattern
31 3 5 7 9 11 13 15 17 19 21 23 25 27 29 1 0
10
20
50
30
40
Volumetric Distribution of a Spray Nozzle For a worn nozzle
Volumetric Distribution of Spray Nozzle Double Coverage - New Nozzles
0 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 1
10
20
50
30
40
Spray Pattern
50
Volumetric Distribution of Spray Nozzle Double Coverage - Worn Nozzles
0
3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 1
10
20
30
40
Spray Pattern
Volumetric Distribution Spray Coverage Triple Coverage - New Nozzles
Spray Pattern
30
40
20
0 1
10
9 5 13 17 21 25 29
Volumetric Distribution Spray Coverage Triple Coverage - Worn Nozzles
50
40
30
20
0
10
1 5 9 13 17 21 25 29 Spray Pattern
Drying Load (for coating application)
Nozzle
Size
Spray
Pressure
Spray
Spacing
Nozzle
Coverage
X's
Total
Flow
Flow
per
Nozzle
Number of
Nozzles
Steam
Consumption
% of Total
Steam Flow
(kg/cm 2 ) (cm) (LPM) (LPM) (KG/HR)
6501
650050
8001
650067
8.4
8.4
2.8
8.4
15
15
23
10
2
2
2
3
19.5
9.8
7.6
20.1
0.65
0.33
0.38
0.45
30
30
20
45
656
328
254
674
13.4%
6.3%
4.8%
13.9%
Spray System
Recommendations
Spray Tips - 650050
Coverage - Double Overlap / 5 Offset
Boom - Easily Changeable Tips/Booms
Filters - 70 to 100 Microns
Pumps - Gear Pumps
Mixing - Direct Injection
Water - 100+ ppm Calcium and Alkalinity
Temperature - As is (non heated)
Flow Meters - Micromotion (Mass Flowmeters)
Chemicals - PVA/Kymene/Release
O
Adhesive Type Comments
poly (aminoamides) Commercial materials crosslinked with epichlorohydrin 48-70
polyamides polyacrylamide 165 ployvinyl pyrrolidone 126-174
polyamines commercial ethylene dichloride alkylamine type -18-20
polyvinyl alcohols commercial 68-75
polyvinyl acetate 28
polyethers polyethylene oxide (PEO) -67 polypropylene oxide (PPO) -75
poly (acrylic acid) 106
cellulose derivatives methyl cellulose 150 ethyl cellulose 43
hemicellulose various types 150-220
Glass Transition Temperatures of Common
Dryer Coating Chemicals
T (C) g