Synthetic Papers based on biaxially oriented films

Synthetic Papers based on
Biaxially Oriented Films
Brückner Maschinenbau GmbH, Siegsdorf, Germany
Dr. J. Breil, Dr. M. Wolf, J. Sänze
19. Leobener KunststoffKunststoff-Kolloquium, 16. & 17.11.2006
Überblick:
 1) Einleitung
 2) Definition Synthetisches Papier „Syn Pa“
 3) Verfahren zur Produktion biaxial orientierter Folien –
Vergleich simultanes/ sequentielles Verfahren
 4) Dichtereduktion durch den Verstreckungsprozess
 5) Beispiele experimenteller synthetischer Papiere
 Basis Polypropylen, dichtereduziert, mehrlagig
 Basis Blends, z. B. PET/ PP oder PA6/PP, dichtereduziert
 Geschäumte Systeme
 7-Lagen Barrierefolien
 6) Zusammenfassung und Ausblick
© Brückner
1) Introduction: Requirements to film packagings
Advertising
• Optics
• Printability
- brand name
- attractivity
Protection
Environmentfriendly
• Mechanical
• Water vapour
• Gas ( O2, CO2, …)
• Light
• Aroma,taste
• Seal integrity
• Production
Processing
• Minimization of
material requirement
• Disposal
Econimcs
• Cost effective
production
• Suitability for fast
packaging machines
© Brückner
Improvement of properties by a stretching process
3500
CPP
BOPP
90
500 500
70
4
250
560
5
1,5
MD
1500
160
160
50
850
10
200
100
60
30
TD
tensile strength
[N/mm²]
MD TD
Elongation
at break
[%]
Mechanical properties
H2O
Haze
Gloss
[%]
[%]
Optical properties
g 25µm
m² d
O2
CO2 N2
cm³ 25µm
m² d bar
Barrier properties © Brückner
Share of thermoplastics for oriented films
Production capacity 2002 worldwide
PVC
Rawmaterial
PA
Others
Others
PS
PET
PP
1000
t/a
%
Share
PP
PET
PS
PVC
PA
Others
Others
4.970
66,0
1.780
23,6
480
6,4
100
1,3
120
1,6
80
1,1
Sum
7.530
100,0
© Brückner
Classification of BOPP application areas
Market-
Growth
share
Standard products:
Biscuit & cookies
31%
5%
Chips & Snacks
15%
7%
Candies
10%
6%
Noodles
8%
3%
Others
19%
Special products:
Labels
8%
8%
Ice cream
5%
10%
Others (new)
4%
Worldwide BOPP production capacity 2002: 4,97 Mio. t/a
Worldwide BOPP SYN PA production capacity 2002: ?????? t/a
© Brückner
2) A Definition of Synthetic Paper
 SYN PA is a film produced by extrusion:
 which contains high amounts of fillers/ pigments
 with a white opaque, paperlike appearance
 with high stiffness, good slip and antistatic properties
 with microscopic vacuoles and/or foam structures
 which is printable and writeable
 with three- or morelayered film structures possible
 offering all attributes of traditional cellulosic paper
 Restriction to biaxially stretched film, e.g. based on
Polypropylene as film forming polymer (Paper production
by using synthetic fibers shall not be discussed here)
There is not only one form of „SYN PA film“
© Brückner
Thickness Ranges and typical Applications
Thickness [µm]
Recommended Applications
50-180 µm
Pressure sensitive, cut and stack, and wrap-around labels; release
liners, posters ink jet printing base
75-100 µm
Pressure sensitive, wrap-around and in-mold labels
75-200 µm
Cut and stack and wrap around labels, posters, maps, shopping bags,
business cards, calendars, banners
75-250 µm
Labels, books, posters, calendars
75-400 µm
Maps, posters, tags, cards, charts, menus, phone cards, calendars,
banners
130-700 µm
Carriers, files, folders
250-1000 µm
Cards, tags, book covers, folders, charts, maps
© Brückner
Synthetic Paper
© Brückner
Advantages of Synthetic Paper
Advantages












Higher wet strength
Higher dimension stability in wet condition
Higher folding strength
Low density
Low anisotropy
Higher tear resistance
Heat-sealable, thermoformable
Low surface roughness
Flexible techniques for production
Non-sensitivity against humidity, oil, fat, greases
Good Barrier Properties against water vapour and gases
Low waste water and air pollution in production
© Brückner
About the history of SYNPA-production:
 End of 60s and beginning of 70s the development of SYNPA started
 SYN PA production was thought to be less expensive
 especially in Japan and Great Britain because of rare timber existence
Between 1980 and 1995 the market share of SYNPA is <2%,
in the light of a constant fall in prices for conventional papers
Price for a coated, high grade cellulosic paper: ~1.600-1.700 €/ t
Price for a single side coated 75µm SYNPA : ~4.000 €/ t
Usually für SYNPA: Price in €/ m2
Today SYNPA is used for high price special applications
Basic patents are free  it is not to be expected, that anyone will
succeed in exclusively securing patent rights in the field of synthetic
paper (Basic patents between 1960 and 1970, until 2002 110 patents
in the field of SYN PA, mainly NANYA and Oji-Yuka)
© Brückner
© BRÜCKNER
Synthetic Paper Products and Players
Company
Trade Name
Resin
Comments
American Profol
Arjobex
B&F Plastics
Cosmo Films Ltd.
ExxonMobil Films
Flexcon
Grafix Plastics
Granwell
Harrier
Hop Industries
Propaper
Polyart
Polyprint
CMP III
Label-Lyte
AlphaMax
GrafixPro
Polylith
Paperfeel
Hopsyn
PP
HDPE
Polyester
PP
PP
3-layer cast film
Clay-coated on both sides, oriented
Talc (20%)
BOPP uncoated
BOPP clay-coated, corona treated
Labels
Mile High Eng
Denver, CO
Accuplot
NanYa Plastics
Polyolefin
PP
HDPE
PP
TiO2, CaCO3, monolayer
3-layer coex
Calendered Film from Nan Ya
Dura-Lite
PP
Outdoor posters, semi-gloss finish, needs pigment
inks to keep water proofing
3-layer with clay coating
Plastics Suppliers
Duraflex
Polyflex
V-Max
BOPS
BOPS
Policrom
PPG
SCO-PAT
Teslin
A Schulmann
Toyobo
Transilwrap
Van Leer
Yupo Corp
Papermatch
Crisper Opaque
Proprint
Valeron
Yupo
Versatile Polyolefin
PE
BOPP, Polyester
Microporous film, silica-filled, single-layer (HiSil),
uncoated
HDPE
Fully compounded or in concentrates
PP
Cross laminated
BOPP
Talc-filled
Coated and Uncoated
© Brückner
[tpa]
Synthetic Paper Market by Resin, 2000 – 2005
50
45
40
35
30
25
20
15
10
5
0
2000
BOPP
HDPE
2005
others
© Brückner
Production Capacity SynPa Worldwide
Country
Company
North
Yupo U.S.A.
America Arjobex
Mobil
Europe Arjobex
Mobil
Taiwan NanYa
Line Capacity Production Domestic Export Comment
Rate
1
10000
9500
6000
3500 U.S.A. 60%, EU: 40%
2
7000
6000
6000
HDPE
4
Label
2
7000
5000
5000
3
2
50000
24500
5400 19100
Japan
Yupo Co.
Chisso
3
1
Others
Shorko
Cosmo Film
1
1
28000
2400
19000
16000 3000
Australia
India
© Brückner
Synthetic Paper Lines from Brückner
Customer
Year of
Start-Up
Country
Capacity
[ tpa ]
Arjobex
1988
UK
3000
Arjobex
1991
USA
3000
Nan Ya
1998
Taiwan
25000
Nan Ya
2001
Taiwan
25000
Nan Ya
2003
Taiwan
31500
Nan Ya
2003
Taiwan
31500
Nan Ya
2005
China
31500
Nan Ya
2005
China
31500
Nan Ya
2005
Vietnam
31500
© Brückner
Layer Structures of Synthetic Paper, examples
Single Layer Comprises:
60,0 %
25,0 %
7,0 %
8,0 %
Two / Three Layer Comprises:
Polypropylene
CaCO3
TiO2
PP-wax
Core Layer:
77,5 %
Polypropylene
15,0 %
CaCO3
2,5 %
TiO2
5,0 %
MSA-PP wax
Skin Layer (2-3 µm):
57,0 %
Polypropylene
27,5 %
CaCO3
7,5 %
TiO2
0,5 %
MSA-PP wax
7,5 %
PP-wax
MSA-PP wax:
 Better binding of the pigments
 Better bonding of the layers
PP-wax:
 Viscosity reduction
 Surface coating
 Wetting and embedding of the
pigment particles
© Brückner
Film Sample: 80µm 5-layer white opaque film – pearlized - heatsealable
A:
B:
C:
D:
E:
1,0 µm
1,0 µm
74,0 µm
2,0 µm
2,0 µm
Film Test Results:
Description
No
1
2
3
4
5
-TD
-MD
Tensile Strength
-TD
-MD
Elongation at Break
-TD
-MD
Modulus of
-TD
Elasticity
F/F- T/O - µs
Coefficient of
F/F- T/O - µk
Friction
Thickness
Unit
Average
Method
µm
N/mm²
N/mm²
%
%
N/mm²
N/mm²
—
—
80
104
171
135
34
1534
2744
0,21
0,2
DIN 53370
DIN 53455
DIN 53455
DIN 53455
DIN 53455
DIN 53457
DIN 53457
DIN 53375
DIN 53375
6
Haze
%
—
ASTM 1003
7
Gloss
—
89 / 86
ASTM 2457
8
Opacity
9
Thermal Shrinkage
%
%
%
91
3,9
2
DIN 53146
BMS TT 02
BMS TT 02
10 Density
g/cm³
0,68
ASTM 1501
11 Wetting Tension
mN/m
42
ASTM 2587
-MD
-TD
Terpolymer / Slip + Antiblock MB
Homopolymer + slip/antistatic MB
Homopolymer + White MB + Pearlized MB
Homopolymer + White + Antistatic MB
Terpolymer / Slip + Antiblock MB
Applications:
• Name cards
• Menus
• Biscuits
• Labels
• Leaflets
• Sheets for advertisement
• Calendars
• Lamination to aluminum
• 2 Sheet lamination
• Labels for Bottles and Boxes
Film Requirements:
• High Opacity
• High Yield due to low density
• High surface treatment for good
printability
• Reasonable slip properties
• Reasonable antistatic properties
© Brückner
Base Raw Materials for the Core and Intermediate Layers (Examples)
Homopolymer BOPP Grade or special grades, eg. high cryst.
Calcium Carbonate CaCO3 or other mineral fillers
Additives, e.g. Slip, Antistatics, compatibilizers, HC resins
PP in Mixture with other Polyolefins, e.g. PE or thermoplastics
like PA6, PBT, PET
Base Raw Materials for the Skin Layers (Examples)
Homopolymer BOPP Grade or
Copolymer BOPP Grade for sealing applications
TiO2, CaCO3 or other mineral fillers
PP in Mixture with other Polyolefins,
e.g. PE or thermoplastics like PA6
© Brückner
Example Formulations and purposes of the different layers
Formulation
1. PP with anorganic fillers
Core layer
2. Chemically foamed PP-layer
Intermediate
layer
Skin layer
Purpose
 Increase in stiffness
 Opacity
 Density reduction of the
stretched film
1. High crystallinity PP
 Increase in stiffness
2. PP / PA - blends
 Increase in opacity
1. PP with anorganic fillers – high
content
2. Pure homo- or copolymer






Paperlike haptic
Surface roughness
Printable
Coatable
Gloss
Coatable
© Brückner
Increasing possibilities by using 5-layer Technology
 Excellent white film with high gloss: Film density and opacity are
functions of film thickness, orientation filler contents and type of
fillers. Five layer structures offer a broad spectrum in terms of film
density, gloss, opacity, whiteness and heatsealability.With three
layer strucure it is not possible to get:
 for non heatsealable film:
 High gloss, high opacity and low density
 for heatsealable film:
 High density, high opacity and high gloss
 Worst Combination: High gloss, high opacity and low density
 Cost savings due to lower additivation
 An increased percentage of recycled material can be processed
 Three- and five layer film with the same equipment
© Brückner
Concept of a Synthetic Paper Line
• Machine design for high output in thick film up to 200
µm
• Twin screw extrusion with direct additivation
technique
• All coextruders twin screw extruders
• 5-layer die design recommended
BR/BHP
miami/!s_dtp/bhp/folien/Folien/SynPa Extrusion
© BRÜCKNER
© Brückner
5-Layer Coextrusion System with Twin Screw
Output: 2400 kg/h+4 x 190kg/h
BR/BHP
miami/!s_dtp/bhp/folien/Folien/5-Layer CoEx
© BRÜCKNER
© Brückner
Extrusion
Main Extruder
•
•
•
Co-rotating twin screw extruder
Direct powder feeding (Brückner patent)
Screw for optimum mixing of powder and PP in
agglomerate free quality
Moisture and volatiles removal by vacuum (no
drying necessary)
Controlled melt temperature
•
•
Coextruder
•
•
•
•
•
VOB/ET
Twin screw extruders for all coextruders
Screw for excellent melt quality
Improved optical properties by moisture and
volatiles vacuum removal
No predrying of moisture sensitive additives
Controlled melt temperature
miami/!s_dtp/bhp/folien/Folien/SynPa Extrusion
© Brückner
© BRÜCKNER
3) Processes for the production of biaxially oriented films
Sequential Stretching
MDO - TDO
Simultaneous Stretching
Pentagraph, Spindle, LISIM
Double-Bubble
© Brückner
LISIM® Principle
Linearmotor Simultaneous Stretching technology
Clips
Linear motors
Simultaneous stretched film
Cast-film
© Brückner
Comparison Sequential / Simultaneous Stretching Processes
Simultaneous Stretching
Sequential Stretching
TD
10
9
8
7
6
5
4
3
2
1
MD
Useful area
MDO
TDO
10
9
8
7
6
5
4
3
2
1
MD
TD
Useful area
LISIM® Simultaneous stretch. technology
© Brückner
Comparison of mechanical film properties:
Sequential / Simultaneous
LISIM®
Sequential
Stretching ratio
(MD x TD)
Tensilestrength
[N/mm²]
Elongation at
break [%]
E-modulus
[N/mm²]
5x9
8x8
10 x 5
MD
140
258
310
TD
290
252
208
MD
200
78
52
TD
55
82
110
MD
2000
3060
4070
TD
3500
3130
2685
© Brückner
Selected current BOPP-trends:
 Low and very low sealing copolymers (SIT down to 80°C).
 More layer film structures, e.g. 7-Layer barrierfilms with
EVOH as barrier material.
 Development of copolymers for higher barrier values of metallized films
 Printable Cigarette film.
 Development of high speed resins.
 Material savings by thickness- and density reduction:
 Formation of vacuoles by adding matrix incompatible organic or
anorganic fillers (CaCO3, PBT).
 Use of chemical foaming agents and subsequent simultaneous
stretching.
© Brückner
4) Density reduction: Formation of vacuoles by incompatible additives
(Inorganic, organic e. g. PBT, -PP)
Y
Vacuole
Z
Particle
X
Polymer matrix
Side view
Top view
Sequential und simultaneous
© Brückner
Parameters influencing the Cavitation
Influence of CaCO3 Content
Influence of MDO Temperature
Influence of MDO Stretching Ratio
Influence of TDO Stretching Ratio
© Brückner
BOPP SYN PA Density as a function of the filler´s nature
BOPP-SYN PA
Density [g/cm3]
0.79
0.69
0.57
Talcum
CaCO3
TiO2
15% filler
© Brückner
© Brückner
Stearic Acid as a wetting agent for hydrophobisation of
CaCO3 during the extrusion process
70 °C
~ 245 °C
+ T °C
CaCO3 + Stearic Acid
Ca-Stearate + H2O +
CO2
A wide range of CaCO3 types with and without surface treatment
was available for our work
© BRÜCKNER
© Brückner
Laboratory trials with precipitated CaCO3 fillers (Company Solvay):
PCC properties, controlled by the precipitation process
Particle form
Aragonit, Needles
Calcit, Scalenoid
Calcit Rhomboid
Primary particle diameter: 50 - 500 nm
© Brückner
5) Examples of synthetic papers
REM-photograph of a sequentially produced, densityreduced 3- layer white film with a density of 0.68 g/ cm3.
© Brückner
Properties
Unit
SYN PA 3-layer
sequential
SYN PA 3-layer
simultaneous
Thickness
µm
100
87
DIN 53370
N/mm²
N/mm²
62
122
123
110
DIN 53455
DIN 53455
Elongation MD
at break
TD
%
%
112
37
73
57
DIN 53455
DIN 53455
E- Modulus MD
TD
N/mm²
N/mm²
981
1690
1775
2035
DIN 53457
DIN 53457
-
14
12
68
15
ASTM 2457
ASTM 2457
Opacity
%
94
79
DIN 53146
Density
Endfilm
g/cm³
0,68
0,91
DIN 53420
Tensile strength
Gloss
MD
TD
T
O
Method
© Brückner
Properties
Unit
Thickness
µm
19
34
DIN 53370
N/mm²
N/mm²
99
174
124
128
DIN 53455
DIN 53455
elongation MD
at break
TD
%
%
117
34
53
41
DIN 53455
DIN 53455
E-Modulus MD
TD
N/mm²
N/mm²
1426
2618
1800
1990
DIN 53457
DIN 53457
Density
endfilm
g/cm³
0,75
0.73
DIN 53420
Tensile
strength
MD
TD
„Pearlized film“
sequential
10 % CaCO3
„Pearlized film“
simultaneous
Method
20% CaCO3
Improvement of mechanical properties in machine direction possible.
Possibly improved behaviour on packaging machines (Project).
© Brückner
Other simultaneous stretched, density reduced systems:
PP/ PA6/ CaCO3-blend: Thickness (128 µm), highly opaque (98%)
white film with a density of 0.46 g/cm3, low water vapour
permeability, possible application as label or synthetic paper.
© Brückner
Other simultaneous stretched, density reduced systems:
PET/ PP/ CaCO3-blend: Thickness (120 µm), opaque (62%)
and stiff white film with a density of 0.97 g/cm3 (BOPET-film:
1.39 g/cm3), possible application as label or stiff synthetic paper.
© Brückner
Properties
Unit
„Pearlized film“
simultaneous
blend PP/
PA6/ CaCO3
breathable Method
film
Thickness
µm
34
128
83
DIN 53370
Tensile
strength
MD
TD
N/mm²
N/mm²
124
128
45
56
10
10
DIN 53455
DIN 53455
elongation
at break
MD
TD
%
%
53
41
69
40
24
10
DIN 53455
DIN 53455
N/mm²
N/mm²
1790
1990
600
770
160
207
DIN 53457
DIN 53457
-
53
57
16
16
12
13
ASTM 2457
ASTM 2457
Opacity
%
58
98
95
DIN 53146
Density
endfilm
g/cm³
0,73
0,46
0,52
DIN 53420
22% CaCO3
60% CaCO3
E-Modulus MD
TD
Gloss
T
O
20% CaCO3
© Brückner
Density reduction by foaming processes
Foaming process at the die exit, pressure increase towards die
© Brückner
Variation of endfilm properties by:
Use of the more layer technique: Foamed core with highly filled
rather smooth skin layers as foamed labels:
Skin layer with
Antiblock additive
Foamed
core
Skin layer
© Brückner
Variation of endfilm properties by:
• Use of different matrix polymers and raw material formulations:
As matrix polymers we used:
polypropylene-homopolymers,
polypropylene-block-copolymers,
high crystallinity polypropylene grades,
long chain branched polypropylene grades to increase the
melt strength,
blends thereof
Addition of different fillers like e.g. CaCO3 or TiO2 to influence
the surface properties, density reductions down to 0.30 g/ cm3,
wallpaper like structures, use of colour batches.
Use of other matrix polymers, e.g. PET or PA6.
High flexibility regarding machine settings (Stretching ratio MD
and TD, stretching temperatures, relaxation a.o.).
© Brückner
Structure of a density reduced, opaque, barrier BOPP film
Simultaneous biaxial orientation
Terpolymer
Homopolymer, CaCo3
1,1 µm
12,7 µm
Adhesive Layer
0,5 µm
EVOH
1,4 µm
Adhesive Layer
0,5 µm
Homopolymer, CaCo3
12,7 µm
Terpolymer
1,1 µm
Gauge:
30 µm
 Density: 0,78 g/ cm3
 OTR:
1,2 cm3/ m2 d bar
23°C/50% r.h.
 WVTR:
1,2 g/ m2 d
23°C/0 - 85% r.h.
© Brückner
Possible Applications: Research Project „Thin Films“
Project coordination
Database
Simulation
End user
Filmproduction
simultaneous
sequential
Metallization
SiOx
Lamination
Print
Adhesive
Packaging
Packaging
properties
e.g. haptics
© Brückner
Brückner Synthetic Paper R & D Activities
Year
R & D Activity
1991
Development of biaxially oriented Synthetic Paper on
Brückner Sequential Pilot Line
1994
Introduction of Twin Screw Extrusion for
Synthetic Paper
1995
Printing Tests with Synthetic Paper
1996
Patent DE 19622082 Process for Synthetic Paper
1997
Patent WO 097/28948 Direct Additivation Process
1998
Transfer of Direct Additivation Process to
Production Scale
1998
Patent DE 19840991 Foamed Synthetic Paper
1999
Development of biaxially oriented Synthetic Paper on
Brückner Simultaneous Pilot Line
2001
Study on Coating Process for Synthetic Paper
2002
Experiments on Blend based Density Reduced Systems
2005
Development of White, Density Reduced 7-Layer Barrier Film
© Brückner
LISIM® Pilotline
© Brückner
LISIM® pilot line for simultaneous stretching
Film types
PET
PP
PA
1 – 150
3 – 60
5 – 25
Stretching ratio MD
3–6
6 – 10
3–5
Stretching ratio TD
3–5
5 – 10
3–5
[m/min]
150
150
50
[kg/h]
250
200
70
Thickness range
Speed (max.)
Net output
Winder
(max.)
[ µm ]
LISIM®
stretching
oven
IRpreheating
Chill-roll
Extrusion
© Brückner
Laboratory Stretching Frame
 Low amounts of material needed
 Comparison of materials or mixtures
 Data for upscaling experiments
mode: simultan bei 155°C 7,5x7,5; 400%/s
35,00
E27_S
30,00
E32_S
Force [N]
25,00
E38_S
20,00
E44_S
15,00
E47_S
10,00
E44_N
5,00
E32_N
0,00
1
2
3
4
5
TD-Stretching Ratio [-]
6
7
8
© Brückner
Upscaling Process
Method





Lab-Stretching Unit
Evaluation of Process Window
Optimisation of Film Properties
Measurement of Stretching Forces
Simulation with FEM-Method
Upscaling to production scale
Pilot-Line
Advantages
 Demonstration of the potentials of the
LISIM® - Technology
 Basic R & D for film stretching
 Development of new film types
 Development of new components
 Production of Sample Rolls for Pre-Marketing
Production-Line
© Brückner
Path Forward and Conclusion
 There is no unambigious definition for a synthetic paper
 Even under the restriction to biaxially oriented films there is a wide
range regarding use of raw materials, processing conditions, film
structures and endfilm properties
 New driving forces could be 7-layer white barrier films or the use of
thermoplastics from renewable sources, e.g. PLA
 Additionally coating applications are possible
We do not think, that conventional cellulose papers could be
substituted in the near future
but…
SYN PA can be a high priced supplementation for special applications
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Thank you very much for your attention!
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One Main difference between simultaneous and sequential
stretching: Significantly higher stretching speeds
during the sequential MDO-stretching:
About 20% CaCO3 for a comparable density reduction.
Possible advantage by using a direct dosing equipment.
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Advantages of 5-Layer Technology
Film Properties
High Flexibility
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Enhanced transparency
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Excellent white film with high gloss
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Special applications
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Ready for new materials and future filmtypes
3- and 5-layer film with the same equipment
Wide application range for white-opaque films
Raw Material
Application
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An increased percentage of recycled
material can be processed
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Savings due to lower additivation
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Self Adhesive Labels (Matt Or Glossy)
Wrap around labels
In-Mould Labels (Injection)
In-Mould Labels (Thermo Forming)
Film For Lamination To Paper, PE and other
Films
Overwrapping
Pressure Sensitive Labels
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General Film Structure for Synthetic Paper
Film structure for synthetic paper with foamed core layer
PP filled with TiO2 or
other white pigments
Homo-PP filled with
CaCO3 drawn to a
defined foamed
structure
Remark:
For the skin layers either homo-PP or copo-PP can be
used.
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