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1 Omya AG
Calcium Carbonate in Blown HDPE Film
New Developments to increase Productivity and Profitability
Version 2.1 - October 2003
2 Omya AG
CaCO3 in Polyolefines : Oriented Lamellae
Polyolefines Matrix
CaCO3 Particles
Bridge(oriention of lamellea)
Oriented Layer
3 Omya AG
Estimation of Matrix Ligament Thickness
=d x[ ( / 6 )1/3 - 1] x exp[(ln )2]β σΛ π φd = number average geom.. mean diam. of particles
β = geom.. constant depending on assumed packing :1.0 for cubic lattice, 1.09 for body-centered cubic,1.12 for face-centered cubic
φ = volume fraction of particles
σ = geom.. std dev. of particle size distribution
Ref : Bartczak et al. Polymer 40 (1999) 2331
Brittle Behavior
When ligament thickness is larger than 2 times the thickness
of the oriented crystallization layer around the particles.
Ref : Bartczak et al. Polymer 40 (1999) 2331
Filler / Rubber Particle
Bulk Matrix
Oriented Layer
Ductile Behavior
When ligament thicknessis less than 2 times the thickness
of the oriented crystallization layeraround the particles
andmaterial with reduced plastic resistance
percolates through the blend.
* Connecting lines show orientation of lamellae ininter-particle ligaments
8 Omya AG
Objective
To introduce CaCO3 in PE Blown Film in order to improve profitability by enhancement of productivity and
mechanical properties.
9 Omya AG
New Concept - Method’s Description
1- To produce a concentrate of a fine coated CaCO3
To use the base resin from film producer as the carrier for a 65% to 75% Masterbatch
2- To introduce this Masterbatch till 25 % CaCO3 in the film extrusion line
Increase the screw rpm to maximise the benefits of CaCO3
No additional changes are required
10 Omya AG
Trials & Process Conditions
KIEFEL EXTRUDER COMPEX 80 SAScrew Size : 80 mm X 25 DDie Diam : 200 mm X 1.4IBC System with Aero-CoolOutput without CaCO3 : 260 kg/hr.Specific Screw Output : 2,56 Kg/rpm/hr
Film Extrusion Line
Basic Polymer Blend
80% Unimodal HDPE + 15% butene LLDPE + 5% White
Masterbatches 65 % Omyafilm + LLDPE
11 Omya AG
Process Conditions
Layflat Width 1440 mm
Initial Thickness (without CaCO3) : 14 µ
then downgauged Film to work at identical Weight
by adding 10 %,17,5 % and 25 % of CaCO3
Production Programme
12 Omya AG
Production Enhancement
• Melt Pressure
By introducing CaCO3 in the screw, melt pressure dropsallowing an increase of screw speed.
Lower manufacturing cost per unit (bag)
13 Omya AG
458
bar
550
bar
505
bar
476
bar
-16,73%
-13,45%
-8,18%
0,00%
400 bar
425 bar
450 bar
475 bar
500 bar
525 bar
550 bar
575 bar
0% 5% 10% 15% 20% 25% 30%
CaCO3 Pigments
-27,3%
-22,7%
-18,2%
-13,6%
-9,1%
-4,5%
0,0%
Variation Melt Pressure
14 Omya AG
Production Enhancement
• Higher Spec. Output
internal volume of the screw will be reduced
viscosity of the blend will be reduced
higher melt homogeneity
Increase of the blend density
higher efficiency of the grooved feed section of the extruder
15 Omya AG
Variation Specific Output
3,21
3,002,87
2,57
1,1591,0951,0380,97
0,0
0,5
1,0
1,5
2,0
2,5
3,0
3,5
0 % 5 % 10 % 15 % 20 % 25 %
CaCO3 Pigments
Mix
ture
Den
sity
/ Sp
ec O
utpu
t
Spec. Output [kg/h/rpm]
Mixture Density [kg/dm3]
+ 25,2%
+19,5%
16 Omya AG
Production Enhancement
• Bubble stability improved
Faster cooling of blown bubble thanks to higher thermal conductivity of CaCO3
• Neck Height could be increased from 8 X Die Diam to 13 X.
17 Omya AG
Thermal Conductivity
-
0.50
1.00
1.50
2.00
2.50
3.00
[W/ M°K]
PP LLDPE HDPE CaCO3
18 Omya AG
Mechanical Properties Enhancement
• Increased Dart Drop Impact Strength
Toughening of PE matrix thanks to addition of CaCO3.
Possibility of down-gauging
19 Omya AG
12,6
19 g
/µ
16,1
00 g
/µ
16,9
00 g
/µ
17,2
50 g
/µ
0,00%
27,59%
36,70%33,93%
10 g/µ
11 g/µ
12 g/µ
13 g/µ
14 g/µ
15 g/µ
16 g/µ
17 g/µ
18 g/µ
0,0% 2,5% 5,0% 7,5% 10,0% 12,5% 15,0% 17,5% 20,0% 22,5% 25,0%
CaCO3 Pigments
-20,8%
-14,8%
-8,9%
-3,0%
3,0%
8,9%
14,8%
20,8%
26,7%
32,6%
38,5%
Variation Dart Drop Test
20 Omya AG
Mechanical Properties Enhancement
• Increased Dart Drop Impact Strength
Toughening of PE matrix thanks to addition of CaCO3.
Possibility of down-gauging
• Higher Elmendorf Tear Strength
21 Omya AG
7,71
5 m
N/µ
10,2
50 m
N/µ
11,2
54 m
N/µ
10,7
80 m
N/µ
0,00%
32,86%
45,87% 39,73%
7 mN/µ
8 mN/µ
9 mN/µ
10 mN/µ
11 mN/µ
12 mN/µ
0,0% 2,5% 5,0% 7,5% 10,0% 12,5% 15,0% 17,5% 20,0% 22,5% 25,0%
CaCO3 Pigments
-9,3%
0,0%
9,3%
18,6%
27,9%
37,2%
46,5%
Variation Elmendorf MD
22 Omya AG
Variation Elmendorf TD
75,4
23 m
N/µ
110,
120
mN
/µ
130,
116
mN
/µ
128,
000
mN
/µ
0,00%
69,71%72,52%
46,00%
60 mN/µ
70 mN/µ
80 mN/µ
90 mN/µ
100 mN/µ
110 mN/µ
120 mN/µ
130 mN/µ
140 mN/µ
0,0% 2,5% 5,0% 7,5% 10,0% 12,5% 15,0% 17,5% 20,0% 22,5% 25,0%
CaCO3 Pigments
-20%-12%-4%4%12%20%29%37%45%53%61%70%78%
23 Omya AG
Mechanical Properties Enhancement
• Increased Dart Drop Impact Strength
Toughening of PE matrix thanks to addition of CaCO3.
Possibility of down-gauging
• Higher Elmendorf Tear Strength
• Higher secant modulus
Helps in bag production
•Better folding and winding on bag lines
24 Omya AG
Tensile Strength at Break MD
0 N/mm2
10 N/mm2
20 N/mm2
30 N/mm2
40 N/mm2
50 N/mm2
60 N/mm2
0% 10% 17,5% 25%CaCO3 Pigments
25 Omya AG
Tensile Strength at Break TD
0 N/mm2
10 N/mm2
20 N/mm2
30 N/mm2
40 N/mm2
50 N/mm2
60 N/mm2
0% 10% 17,5% 25%CaCO3 Pigments
26 Omya AG
Elongation at Break MD
0 %
100 %
200 %
300 %
400 %
500 %
600 %
0% 10% 17,5% 25%CaCO3 Pigments
27 Omya AG
Elongation at Break TD
0 %
100 %
200 %
300 %
400 %
500 %
600 %
0% 10% 17,5% 25%CaCO3 Pigments
28 Omya AG
Isotropy : CaCO3 Balances Polymer’s Orientation
TD
.MD
MD
TD
Neck Height 8X Die
With CaCO3
.Neck Height 12X Die
Without CaCO3
29 Omya AG
Isotropy : Elmendorf TD/MD
16,501
-57,07
13,672
31,849
25,433
-20,15
-48,19-60-50-40-30-20-10
010203040
0% 10% 17,50% 25%
%
Rate TD/MDAver. Decrease Rate
CaCO3
30 Omya AG
Sealing
Sealing Strength with Omyalene 2021 P
0
2
4
6
8
10
12
0 5 10 15 20 25 30
CaCO3 Pigments [%]
Seal
ing
Stre
ngth
[N/1
5mm
]
Sealing Strength 160° [N/15mm]]Sealing Strength 150° [N/15mm]]Sealing Strength 140° [N/15mm]]Sealing Strength 130° [N/15mm]]Sealing Strength 120° [N/15mm]]
15µm monolayer 82% HDPE 13% LLDPE 5% White MB
change HDPE for CaCO3
keep LLDPE const.
31 Omya AG
Mechanical Properties Enhancement Summary
CaCO3 will bring a homogeneous and isotropic film with upgraded characteristics.
Decreased orientation and equalisationof MD and TD propertiesBetter bubble stabilityNeck length can be increased up to13 X die diameterBUR can be reduced by 10% and abigger die can be used, increasing outputImproved film flatness and thicknesstolerancesBetter roll qualityBetter PrintabilityFaster welding
32 Omya AG
Mechanical Properties Enhancement Summary
Dart drop increased by up to 45%Elmendorf MD tear increased by up to 150%Elmendorf TD tear increased by up to 140%
Thinner film with equal mechanical properties
OR
Same thickness with much improved mechanical properties
33 Omya AG
Process Enhancement Summary
Lower melt pressuresHigher specific screw outputBetter bubble stabilityFaster cooling due to higher thermal conductivity of CaCO3
Better melt homogeneity
=
Higher Extruder Output by up to1% per percent CaCO3
34 Omya AG
Productivity Enhancement Summary
Potential raw material cost savings
Potential to compete with higher
performance resins
Reduction of TiO2 Masterbatch
Elimination of blocking problems
Lower extrusion costs
35 Omya AG
Final Costs Calculation
0 % CaCO3 10% CaCO3 17.5 % CaCO3 25 % CaCO3
Production (mT/Year) 2.660 2.926 3.126 3.325
Total Fixed Costs 236.875 € 236.875 € 236.875 € 236.875 €
Variable Costs 228.359 € 234.147 € 237.660 € 240.878 € Polymer Costs 2.056.111 € 2.246.466 € 2.361.295 € 2.471.805 €
Total Costs 2.521.345 € 2.717.488 € 2.835.830 € 2.949.558 € Price/Kg of Good Film 0,95 € 0,93 € 0,91 € 0,89 €
0,00% -3,88% -5,71% -7,51%0 € - 91.472 € - 165.130 € - 242.442 €
Total Saving Money
36 Omya AG
Additional Benefits
CaCO3 cleans the die and extruder
Shorter changeover times
CaCO3 is an ecological product
Replacing polymer
Neutralising flue gases so preventing acid rain
37 Omya AG
Additional Benefits
Incineration of bags containing CaCO3 decreases CO2 emission
1 Kg of PE gives 2.917 Kg CO2
1 Kg of bags containing 20 % CaCO3 gives 2,602 Kg CO2
- 17,2 % CO2
38 Omya AG
Summary
• Improve physical properties
• Competitive with higher performance resins
• Potential for down-gauging film
• Potential raw material cost savings
• Higher output rates
• Lower manufacturing costs
• Contribute to a cleaner environment
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