specialty carbons for polymer compounds
TRANSCRIPT
imerys-graphite-and-carbon.com
TIMCAL GraphiteTIMREX®
TIMCAL CokeTIMREX®
SPECIALTY CARBONS FORPOLYMER COMPOUNDS
TIMCAL Carbon BlackENSACO®
TIMCAL DispersionTIMREX®
Polymers
2
Imerys Graphite & Carbon
WHAT IS OUR MISSION?To promote our economic, social and cultural advance-ment with enthusiasm, efficiency and dynamism by of-fering value, reliability and quality to ensure the lasting success of our customers.
WHAT IS OUR VISION?To be the worldwide leader and to be recognized as the reference for innovative capability in the field of carbon powder-based solutions.
IMERYS Graphite & Carbon has a strong tradition and history in carbon manufactur-ing. Its first manufacturing operation was founded in 1908. Today, IMERYS Graphite & Carbon facilities produce and market a large variety of synthetic and natural graphite powders, conductive carbon blacks and water-based dispersions of consistent high quality. Adhering to a philosophy of Total Quality Management and continuous process improve-ment, all Imerys Graphite & Carbon manufacturing plants comply with ISO 9001:2008. IMERYS Graphite & Carbon is committed to produce highly specialized graphite and carbon materials for today’s and tomorrow’s customers needs.IMERYS Graphite & Carbon belongs to IMERYS, the world leader in mineral-based specialties for industry.
WHO ARE WE?
HQ Bodio, SwitzerlandGraphitization and processing of synthetic graphite, manufacturing of water-based dispersions, processing of natural graphite and coke, and manufacturing and processing of silicon carbide
Changzhou, ChinaManufacturing of descaling agents and processing of natural graphite
Fuji, JapanManufacturing of water-based dispersions
Willebroek, BelgiumManufacturing and processing of conductive carbon black
Lac-des-Îles, CanadaMining, purification and sieving of natural graphite flakes
For the updated list of commercial offices and distributors please visit www.imerys-graphite-and-carbon.com
Terrebonne, CanadaExfoliation of natural graphite, processing of natural and synthetic graphite
With headquarters located in Switzerland, IMERYS Graphite & Carbon has an inter-national presence with production facilities and commercial offices located in key markets around the globe. The Group’s industrial and commercial activities are man-aged by an experienced multinational team of more than 430 employees from many countries on three continents.
WHERE ARE WE LOCATED?
3
Contents
ENSACO® conductive carbon blackTIMREX® graphite and coke Specialty carbons for polymer compounds
THE PRODUCTS • Introduction to ENSACO® conductive carbon black p. 4 • Introduction to TIMREX® graphite and coke p. 5 • ENSACO® conductive carbon black for polymer compounds p. 6 • TIMREX® graphite and coke for polymer compounds p. 8
TYPICAL APPLICATIONS FOR ENSACO® CONDUCTIVE CARBON BLACK • Electrically conductive plastics p. 10 • Rubber p. 14 • Power cables and accessories p. 17
TYPICAL APPLICATIONS FOR TIMREX® GRAPHITE AND COKE • Self lubricating polymers p. 18 • Filled PTFE p. 20 • Thermally conductive polymers p. 22
4
TH
E P
RO
DU
CT
S
Introduction to ENSACO® conductive carbon black
Conductive carbon blacks are carbon blacks with high to very high stucture (or void volume) allowing the retention of a carbon network at low to very low filler content. The void volume can originate from the interstices between the carbon black particles, due to their complex arrangement, and from the porosity.
TEM picture of ENSACO® 250G carbon black showing the high level of aggregation.By courtesy of University of Louvain (Louvain-La-Neuve)
STM picture of the surface of ENSACO® 250G carbon black 5x5 nm.By courtesy Prof. Donnet - Mulhouse
SEM picture of ENSACO® 250G carbon black illustrating the high void volume.By courtesy of University of Louvain (Louvain-La-Neuve)
The Imerys Graphite & Carbon carbon black process has been developed around 1980 and is commercially exploited since 1982. The plant uses most modern technology. The process is based on partial oil oxidation of carbochemical and petrochemical origin. The major difference with other partial combustion carbon black technologies lies in the aerodynamic and thermodynamic conditions: • low velocity; • no quench; • no additives.
This leads to a material with no or nearly no sieve residue on the 325 mesh sieve and allows the highest possible purity. The granulation process has been developed to achieve an homogeneously consist-ent product maintaining an outstanding dispersibility. It is in fact a free-flowing soft flake characterised by a homogeneous and very low crushing strength that guaran-tees the absence of bigger and harder agglomerates. The process enables the production of easily dispersible low surface area conductive carbon blacks as well as very high surface area conductive carbon blacks. The unique combination of high structure and low surface area also contributes to give outstand-ing dispersibility and smooth surface finish. The low surface area materials show a chain-like structure comparable to acetylene black. The very high surface area materi-als belong to the extra conductive (EC) family. Although ENSACO® carbon blacks are slightly more graphitic than furnace blacks, they are quite close to the latter ones as far as reinforcement is concerned.ENSACO® carbon blacks combine to a certain extent both the properties of furnace and acetylene black, reaching the optimal compromise.
100 nm
100 nm
HOW ENSACO® CONDUCTIVE CARBON BLACKS ARE PRODUCED
5
TH
E P
RO
DU
CT
S
Introduction to TIMREX® graphite and coke
Graphite finds wide application thanks to its favourable combination of properties such as: • low friction, chemical inertness and absence of inherent abrasiveness; • high thermal conductivity, thermal stability and electrical conductivity; • film forming ability on metal surfaces; • relatively inoffensive nature of both powders and products of combustion.
These properties are a consequence of the lamellar graphite structure and the ani-sotropic nature of chemical bonding between carbon atoms. In graphite, three sp2 hybrid orbitals (each containing one electron) are formed from the 2s and two of the 2p orbitals of each carbon atom and participate in covalent bonding with three sur-rounding carbon atoms in the graphite planes. The fourth electron is located in the remaining 2p orbital, which projects above and below the graphite plane, to form part of a polyaromatic π-system.
Delocalisation of electrons in π-electron system is the reason of graphite’s high sta-bility and electrical conductivity. Interlamellar bonding was once thought to be weak and mainly the result of Van der Waals forces, however, it now appears that interla-mellar bonding is reinforced by π-electron interactions. Graphite is therefore not in-trinsically a solid lubricant and requires the presence of adsorbed vapours to maintain low friction and wear.
SEM picture of TIMREX® Graphite showing the perfect crystalline structure.
c/2 = Interlayer distanceLc = Crystallite height
c/2
Lc c
TIMREX® PRIMARY SYNTHETIC GRAPHITETIMREX® primary synthetic graphite is produced in a unique highly controlled graphiti-zation process which assures narrow specifications and unequalled consistent quality thanks to: monitoring of all production and processing stages, strict final inspection, and clearly defined development processes. TIMREX® primary synthetic graphite shows unique properties thanks to the combi-nation of a consistent purity, perfect crystalline structure and well defined texture.
TIMREX® NATURAL FLAKE GRAPHITETIMREX® natural flake graphite is produced in a wide range of products distinguished by particle size distribution, chemistry and carbon content. Imerys Graphite & Carbon mines the graphite from its own source in Lac-des-Îles, Quebec, Canada. Further pro-cessing can be done either in Lac-des-Îles or in our processing plant in Terrebonne, Quebec, Canada. All TIMREX® “naturals” are thoroughly controlled in our laborato-ries to ensure quality, consistency and total customer satisfaction.
TIMREX® COKETIMREX® petroleum coke is calcined at appropriate temperature with low ash and sulphur content, well defined texture and consistent particle size distribution.
HOW TIMREX® GRAPHITE AND COKE POWDERS ARE PRODUCED
6
TH
E P
RO
DU
CT
S
ENSACO® conductive carbon black for polymer compounds
TYPICAL VALUES
PROPERTY TEST METHOD UNIT ENSACO® 150G ENSACO® 210G ENSACO® 250G ENSACO® 260G ENSACO® 350G
Form Granules (*) Granules Granules (*) Granules Granules
BET nitrogen surface areaASTM D3037
m2/g 50 55 65 70 770
OANabsorptionASTM D2414 (1)
ml/100 g 165 155 190 190 320
COAN crushed OANASTM D2414 (1)
ml/100 g 95 95 104 104 270
Pour densityASTM D1513
kg/m3 190 210 170 170 135
Moisture (as packed)ASTM D1509
% 0.1 0.1 0.1 0.1 1 max
Sieve residue325 mesh (45 μm)ASTM D1514
ppm 2 2 2 2 10
Ash contentASTM D1506
% 0.1 0.1 0.01 0.01 0.03
Volatile contentTIMCAL Method 02 (2)
% 0.2 max 0.2 max 0.2 max 0.2 max 0.3 max
Sulphur contentASTM D1619
% 0.5 max 0.5 max 0.02 0.02 0.02
Toluene extractASTM D4527
% 0.1 max 0.1 max 0.1 max 0.1 max 0.1 max
pHASTM D1512
8–11 8–11 8–11 8–11 8–11
Volume resistivityTIMCAL Method 11 (3) (4)
Ohm.cm 2000 max (3) 500 max (3) 10 max (3) 5 max (3) 20 max (4)
(1) Spring: 0.9 lbs/inch; 10 g of carbon black (2) Weight loss during heating between 105 and 950°C (3) 25% carbon black in HDPE Finathene 47100(4) 15% carbon black in HDPE Finathene 47100
(*) ENSACO® 150 and ENSACO® 250 are also available in powder form.
7
TH
E P
RO
DU
CT
S
TYPICAL EFFECTS ON POLYMER COMPOUNDS
PROPERTY ENSACO® 150G ENSACO® 210G ENSACO® 250G ENSACO® 260G ENSACO® 350G
Form Granules (*) Granules Granules (*) Granules Granules
BET nitrogen surface area (m2/g) 50 55 65 70 770
OAN oil absorption (ml/100 g) 165 155 190 190 320
Conductivity
Dispersibility
Purity
Water absorption very low very low very low very low high
Surface smoothness
Electrical/mechanicalproperties balance
Resistance to shear
Comments toapplication domains
MRG(mechanical
rubber goods)
Easy strippableinsulation shields
All polymers
excellent
very good
good
quite good
difficult
(*) ENSACO® 150 and ENSACO® 250 are also available in powder form.
0 25 50 75 150
8
TH
E P
RO
DU
CT
S
TYPICAL VALUES
TIMREX® graphite and coke for polymer compounds
0 25 50 75 150
0 25 50 75 150
0 25 50 75 150
0 25 50 75 150
PARTICLE SIZE RANGE GRADE (µm)
ASH(%)
SCOTT DENSITY(g/cm3)
SURFACE AREA BET (m2/g)
Synthetic graphite
KS graphite KS6KS15KS5-25KS44KS5-44KS150
0.060.050.030.060.020.06
0.070.070.230.190.310.42
26.020.08.69.05.93.0
SFG graphite SFG6SFG44SFG150
0.070.070.03
0.070.19
0.29*
17.05.02.5
T graphite T15T44T75
0.080.070.07
0.100.180.21
13.010.09.8
Natural graphite
PP flake graphite
PP10PP44
<5<5
0.050.11
10.04.8
LSG flake graphite
LSG10LSG44
<1<1
0.080.20
9.35.4
Cumulative size
Large flakegraphite
min. 80% <150 mesh (105 μm)min. 80% >150 mesh (105 μm)
M15080X150
<6<6
0.4*0.6*
1.90.9
Coke
Oversize control10.0PC coke min. 98% <45 μm (air jet sieving)
max. 0,1% >106 μm (air jet sieving)
PC40-OC 0.15 0.47*
GRADE ASH(%)
DENSITY(g/cm3)20°C
PARTICLE SIZEDISTRIBU-TIONd90 (µm)
SOLID CONTENT(%)
Water-based dispersion
LB dispersion LB1300 0.10 1.17 6.5 27.5
GRADE ASH (%)
SCOTT DENSITY(g/cm3)
FORM D90 (µm)
Special grade
C-THERM™ C-THERM™001 <0.3 0.15* soft granules
C-THERM™011 <2.5 0.15* soft granules
C-THERM™002 <0.3 0.04* powder 81
C-THERM™012 <2.5 0.04* powder
* bulk density
9
MEET CONDUCTIVITY TARGETSWITH DEDICATEDIMERYS GRAPHITE & CARBON ADDITIVES
TY
PIC
AL
AP
PLI
CA
TIO
NS
FO
R E
NS
AC
O® C
ON
DU
CT
IVE
CA
RB
ON
BLA
CK
10
ENSACO® conductive carbon blacks find their applications in an unlimited number of plastics. The combination of the polymer type and grade and the carbon black grade are determining the overall electrical and mechanical performance.The main parameter influencing the final conductivity of a finished part in a given polymer is the type and level of carbon black used. The higher the structure of the carbon black, the lower the level of carbon black needed to achieve the required conductivity. Nevertheless, in a minor way, other parameters like the additives in presence, the compounding or processing conditions may also influence the final conductivity of parts.Low surface area conductive carbon blacks show a particular advantage on disper-sion and processing.Percolation curves – correlating the volume resistivity and the carbon black percent-age – are a useful comparative tool to predict the conductivity in place and to select the more appropriate system. These curves are valid for a given formulation and sample preparation technique.The selection of the conductive carbon black will also influence: • the compounding behaviour (dispersibility, resistance to shear, mixing cycle, melt flow index, extrusion throughput);
• the surface appearance of the finished material (number of surface defects); • the mechanical properties(polymer property retention, reinforcement); • the overall price – performance ratio.
Suitable mixing equipments for the preparation of black conductive compounds in-clude internal mixers, twin screw extruders, single screw kneader machines and LCM. The feeding of low bulk density, soft flake-type carbon blacks into extruders re-quires the use of twin screw feeders and separate introduction on an already molten polymer (split feeding technology).
• handling of electronic components: carrier boxes, carrier trays, carrier tapes, etc.; • films: antistatic and conductive films, packaging films, garbage bags, etc.; • automotive industry: fuel injection systems, anticorrosion systems, fuel tank in-let, electrostatically paintable parts, etc.;
• transport: mobile phone parts, wheels, containers, bins, pallets, etc.; • computer: antistatic articles for computer & accessories, CD player, etc.; • health: medical applications, cleanroom equipments, articles for antistatic work-places, etc.;
• antistatic flooring; • heating element; • sensors; • PTC switches; • UV protection and pigmentation.
In the following pages there are some of the results of experimental work carried out on ENSACO® conductive carbon blacks in different polymer compounds.
The data shown here are given as orientation and are valid for the particular formula-tions and sample preparation technique mentioned. (Results in other polymers, full studies and publications are available upon request).
Electrically conductive plastics
THE SELECTION OF A CONDUCTIVE CARBON BLACK
THE PREPARATION OF A CONDUCTIVE COMPOUND
SOME TYPICAL FINAL PLASTICS APPLICATIONS
TY
PIC
AL
AP
PLI
CA
TIO
NS
FO
R E
NS
AC
O® C
ON
DU
CT
IVE
CA
RB
ON
BLA
CK
11
ENSACO® CONDUCTIVE CARBON BLACKS IN HDPE
Various carbon blacks in HDPE
Resistivity vs mixing time - 18% carbon black
Resistivity vs mixing time - 25% carbon black
Influence of the carbon black type on the resistivityThe higher the structure of the carbon black, the lower the percolation threshold.
At a concentration very near to the percolation level, when overmixed, ENSACO® 260G offers a higher consistency in resistivity resulting from its higher shear stability in extreme working conditions.
At a concentration far above the percolation level, both blacks are very stable in resis-tivity when overmixed. ENSACO® 260G shows a consistent lower resistivity.
Volu
me
resi
stiv
ity (O
hm.c
m)
Carbon black concentration (%)
0.10 30 4010 20 50
105
10
107
109
103
ENSACO® 250G
ENSACO® 260G
ENSACO® 350GVo
lum
e re
sist
ivity
(Ohm
.cm
)
Brabender mixing time (min)
04 8 965 7 10
500
100
700
600
400
200
800
300
ENSACO® 250G
ENSACO® 260G
Volu
me
resi
stiv
ity (O
hm.c
m)
Brabender mixing time (min)
3.04 8 965 7 10
5.5
3.5
6.5
6.0
5.0
4.0
7.0
4.5
ENSACO® 250G
ENSACO® 260G
Compounding: laboratory Brabender internal mixer. Processing: compression moulding.
TY
PIC
AL
AP
PLI
CA
TIO
NS
FO
R E
NS
AC
O® C
ON
DU
CT
IVE
CA
RB
ON
BLA
CK
12
Volu
me
resi
stiv
ity (O
hm.c
m)
Carbon black concentration (%)
100
0 25 30105 2015 35
106
104
108
102
ENSACO® 250G LD 0.3
ENSACO® 250G LD 36
N472 LD 0.3
N472 LD 36
P-type LD 0.3
P-type LD 36
Volu
me
resi
stiv
ity (O
hm.c
m)
MFI (230 °C/5 kg) (g/10 min)
100
0 10 100
103
101
104
102
ENSACO® 250Ghigh structure low surface area
N472high structurehigh surface area
Volu
me
resi
stiv
ity (O
hm.c
m)
100
101
103
strands
171
2410 6
4.6E +10
54
pellets + pressedplaques
pellets +injection moulding
105
102
106
104
13.5% ENSACO® 250G
15% ENSACO® 250G
Compounding: laboratory Brabender internal mixer.Processing: compression moulding.
Compounding and processing: twin screw extruder Haake PTW16 and realization of tapes.
Compounding: ZSK25 twin screw extruder.Processing: injection moulding.
ENSACO CONDUCTIVE CARBON BLACKS IN LDPE
ENSACO® CONDUCTIVE CARBON BLACKS IN PP
Influence of the carbon black type and of the MFI of the starting polymer on the resistivityThe higher the structure of the carbon black, the lower the percolation threshold. At equal structure, the carbon black of lower surface area gets an advantage on resistivity that may be coming from the easier dispersion resulting in smoother compounding. The higher the meltflow index of the starting polymer, the lower the percolation threshold.
Various carbon black in LDPE MFI 0.3 and 36 (g/10 min)
Influence of the carbon black type on the resistivity. Relation between resistiv-ity and melt flow indexAt same structure level, the carbon black with the lowest surface area has the small-est impact on fluidity reduction.
PPH MI54 (230 °C/5 kg) with various conductive carbon blacks
Influence of carbon black loading and processing on the resistivityInjection moulding generates more shear than compression moulding. The closest to the percolation, the more visible is that effect. A concentration safety margin can overcome this phenomenon.
Electrically conductive plastics
TY
PIC
AL
AP
PLI
CA
TIO
NS
FO
R E
NS
AC
O® C
ON
DU
CT
IVE
CA
RB
ON
BLA
CK
13
Volu
me
resi
stiv
ity (l
og (O
hm.c
m))
Carbon black concentration (%)
15 1510 20 25
32
121110
87654
ENSACO® 250G
ENSACO® 350G
9
Izod
(kJ/
m2 )
Volume resistivity (log (Ohm.cm))
41 6432 5 8 10 117 9 12
6
5
12
11
10
9
8
7
ENSACO® 250G
ENSACO® 350G
Tens
ile s
treng
th (M
Pa)
Volume resistivity (log (Ohm.cm))
601 6432 5 8 10 117 9 12
62
61
68
67
66
65
64
63
ENSACO® 250G
ENSACO® 350G
Compounding: ZSK57 twin screw extruder.Processing: injection moulding.
Compounding: ZSK57 twin screw extruder.Processing: injection moulding.
ENSACO® CONDUCTIVE CARBON BLACKS IN PC
Influence of the carbon black type on the resistivity
Influence of the carbon black type on mechanical and rheological performancesAlthough the concentration for percolation is double the level with ENSACO® 250G, most mechanical properties are still better.
Tensile strength for both carbon blacks is almost at the same level.
Volume resistivity in function of carbon black loading
Izod impact strength, notched, in function of volume resistivity
Tensile strength in function of volume resistivity
TY
PIC
AL
AP
PLI
CA
TIO
NS
FO
R E
NS
AC
O® C
ON
DU
CT
IVE
CA
RB
ON
BLA
CK
14
Rubber
Carbon black is one of the main ingredients of any rubber compound. Conductive carbon blacks are before all carbon blacks, to be mixed and handled as any other reinforcing or semireinforcing carbon black. They are high structure materials bulky by nature. Although the common carbon blacks are conductive by nature and impart also conductivity to the compounds when used in sufficiently high loading, conduc-tive carbon blacks have the advantage to reach conductivities at lower loading and are often used to give the final boost to a compound already filled with other car-bon blacks. As carbon black structure is the parameter determining the conductiv-ity, structure being an additive property, the combinations of conductive and normal black can be predicted. Specifications of rubber compounds being usually quite complex and conductivity be-ing only one of the numerous physical requirements, the use of carbon black blends is very often the only solution. In some specific cases, especially in special polymers, it occurs that the conductive carbon black is used by its own in order to maintain mechanical properties and processing at a good level.ENSACO® carbon blacks are, quite close to furnace blacks as far as the reinforcing ac-tivity is concerned. Especially the low surface area carbon blacks, grades 150, 250 and 260, are, due to their very easy dispersion, quite performing in most rubber compounds. ENSACO® 350 is also used in some compounds where small additions are required.
A few conductive applications: • belt cover compounds; • flooring; • conveyer belts; • hoses for fuel, for conveying of powders, etc.; • cylinder coating; • shoe soles; • seals.
ENSACO® 150 and 250 are also used in non conducting applications where the com-pounder can take profit of the low surface area and high structure of those blacks: • low hysteresis with relatively high hardness; • good thermal aging; • very good tear strength; • very good dispersion, very good mechanical performance at thin layer.
A few non-conductive applications: • antivibration systems; • textile coating; • membranes; • articles exposed to chipping and chunking.
In the following pages there are some of the results of experimental work carried out on ENSACO® conductive carbon blacks in different rubber compounds.The data shown here are given as orientation and are valid for the particular formula-tions and sample preparation technique mentioned. Results in other polymers, full studies and publications are available upon request.
TY
PIC
AL
AP
PLI
CA
TIO
NS
FO
R E
NS
AC
O® C
ON
DU
CT
IVE
CA
RB
ON
BLA
CK
15
NBR CONDUCTIVE HOSE COMPOUND
CONDUCTIVE CR CONVEYOR BELT COVER COMPOUND
A B
CompoundENSACO® 250
CompoundN-472
NBR NT 3945 100 100
ENSACO® 250 25
N-472 25
N-550 40 40
ZnO 4 4
Stearic acid 0.5 0.5
DOP 30 30
Sulphur 0.4 0.4
Methyl thuads 2 2
Amax 2 2
By courtesy of Bayer
A B
CompoundENSACO® 250
CompoundN-472
Bayprene 610 (CR) 100 100
Buna CB 10 2 2
MgO powder 4 4
N-472 30
ENSACO® 250 30
Vulkanox DDA 1.5 1.5
Vulkanox 4020 0.5 0.5
Ingralen 450 15 15
ZnO powder 5 5
Rhenogran ETU-80 0.2 0.2
Stearic acid 0.5 0.5
By courtesy of Bayer
A B
CompoundENSACO® 250
CompoundN-472
t90% (min) 11.46 11.37
Mooney ML (1+4) at 100° C 45.7 47.2
Vulcanizate data unaged at RT
Shore A Hardness 70.9 72.2
Stress-strain
Elongation at break (%) 339 311
Tensile Strength (MPa) 13.8 14.8
Modulus 100% (MPa) 3.9 4.6
Modulus 300% (MPa) 8.6 10.3
Modulus 500% (MPa) 12.6 14.4
Resistivity (Ohm.cm) 79 360
Tear Strength (N/mm) 32.4 31.8
A B
CompoundENSACO® 250
CompoundN-472
Dispersion rating DIK 86.8 85.8
t90% (min) 20.7 21.8
Mooney ML(1+4) at 100°C 62 64
Vulcanizate data unaged at RT
Shore A hardness 62 64
Stress-strain
Elongation at break (%) 676 540
Tensile strength (MPa) 23.4 22.4
Modulus 50% (MPa) 1.2 1.4
Modulus 100% (MPa) 2.4 2.7
Modulus 300% (MPa) 9.2 11.5
Modulus 500% (MPa) 16.1 20.6
Compression set 24h at 70°C (%)
18 19
Resistivity (Ohm.cm) 100 800
TY
PIC
AL
AP
PLI
CA
TIO
NS
FO
R E
NS
AC
O® C
ON
DU
CT
IVE
CA
RB
ON
BLA
CK
16
FKM CONDUCTIVE COMPOUNDS
Mooney viscosity ML (1+10’), 100°C
Log resistivity (Ohm.cm)
Shore A
t 90% (min)
Compression set (%)
1 2 3 4 5 6 7 8 9
VITON A-32J - Fluoroelastomer 100 100 100 100 100 100 100 100 100
MgO 3 3 3 3 3 3 3 3 3
Ca(OH)2 3 3 3 3 3 3 3 3 3
MT black (N990) 20 - - - - - - 20 20
ENSACO® 250G - 10 20 30 - - - 10 20
N-472 SCF - - - - 10 20 30 - -
VPA-2 1 1 1 1 1 1 1 1 1
Total phr 127.0 117.0 127.0 137.0 117.0 127.0 137.0 137.0 147.0
MT black % 15.7 0.0 0.0 0.0 0.0 0.0 0.0 14.6 13.6
ENSACO® 250G % 0.0 8.5 15.7 21.9 0.0 0.0 0.0 7.3 13.6
SCF N-472 % 0.0 0.0 0.0 0.0 8.5 15.7 21.9 0.0 0.0
Experimental data provided by DuPont Dow Elastomers, Japan
05321 4 7
(*)
96 8
40
20
180
160
140
120
100
80
60
05321 4 96 8
6
24
2018161412108
05321 4 96 8
14
12
10
8
6
4
2
05321 4 96 8
70
60
50
40
30
20
10
05321 4 96 8
1009080
60
40
70
50
302010
(*) Rejected because uncurable. Vulcanizate properties at 177°C for 10 min.
TY
PIC
AL
AP
PLI
CA
TIO
NS
FO
R E
NS
AC
O® C
ON
DU
CT
IVE
CA
RB
ON
BLA
CK
17
Conductive carbon black is used in semicon compounds for conductor and insulator shields. The requirements for those compounds are besides processing, a sufficient electrical conductivity, a smooth or even supersmooth surface finish, and high purity.For strippable or easy strippable compounds these requirements are added to a spe-cific adhesion strength between the insulating layer and the insulator shield. These strippable or easy strippable layers have to peeled of by hand or using a specific peeling device.Typical polymer compositions are polyolefins or copolymers; for strippable com-pounds quite often blends of EVA and NBR are used.
TYPICAL EEA/EBA SEMICON COMPOUNDS
TYPICAL EVA/NBR STRIPPABLE COMPOUNDS
CompoundN-472
CompoundENSACO® 210
CompoundENSACO® 250
Levaprene 450 90 90 90
Perbunan NT 8625 10 10 10
Rhenogran P60 3 3 3
N-472 40
ENSACO® 210 40
ENSACO® 250 40
N-550 40 40 40
Antilux 654 10 10 10
Zn stearate 1 1 1
Rhenovin DDA-70 1.4 1.4 1.4
Rhenofit TAC/CS 4.3 4.3 4.3
Percadox BC-408 5 5 5
Viscosity ML (4+1) 56 44 48
Rheometer@180 t90% 3.6 3.6 3.8
Mechanical properties
Non aged (diff. aged)
Tensile strength (MPa) 16.5 (-19) 16.9 (-15) 16.9 (-15)
Elongation at break (%) 215 (-58) 180 (-50) 170 (-53)
Modulus 100% (MPa) 11 12.2 12.7
Shore A 87 (+7) 90 (+4) 89 (+7)
Peel strength hot air 100°C (N)- after 3 days (N)- after 21 days (N)
755
343
434
Volume resistivity (Ohm.cm) 210 6600 410
CompoundEEA
CompoundEBA
EEA 100
EBA 100
ENSACO® 250 30 30
Peroxide
Mixing cond. L/D15; Feed BC; Truput 30
Resistivity @ RT 7.2 5.6
Resistivity @ 90°C 37 22
Carbon black dispersion: <3μm 97.9 99.4
Die pressure (bar) 229 239
MFI (g/10 min) 23.12 21.39
Specific net mixing energy (kWh/kg) 0.313 0.326
Protrusion (N°/m2) 0 0
Power cables and accessories
TYPICAL EEA/EBA SEMICON COMPOUNDS
18
TY
PIC
AL
AP
PLI
CA
TIO
NS
FO
R T
IMR
EX
® G
RA
PH
ITE
AN
D C
OK
E
Self lubricating polymers
The choice of a polymer-based self lubricating solid for a particular application depends mainly upon the operating conditions of: temperature, chemical environment and the maximum values of pressure (p) and sliding speed (v). For each polymer or composite material, a pv limit is quoted, which corresponds to the pressure times the sliding speed at which the material fails, either due to unacceptable deformation, or to the high fric-tional energy dissipated causes surface melting, softening and excessive wear.The pv limit of a polymeric material may be increased by increasing its mechanical strength (resistance to deformation), thermal conductivity (reduction in surface tem-peratures) and by decreasing friction (reduces frictional heating). In practice, thermo-plastics (with the exception of PTFE) are mainly used as pure solids, since their wear resistance and frictional coefficient, are satisfactory for most applications. Solid lubri-cant fillers or fibre reinforcement (glass fibres, carbon fibres, textiles) are only em-ployed under the more extreme conditions of load and speed.The major polymers employed as self lubricating solids/composites, are illustrated below.
Graphite powder is widely used in polymer composites, either alone or in combination with reinforcing fibres, PTFE or various inorganic fillers, e.g. mica, talc. Applications include gears, dry sliding bearings, seals, automotive and micro-mechanical parts.
The properties of graphite which favour its use in polymer composites are: • low friction lamellar solid (reduces friction); • tendency to form a transfer film on the countersurface (assists in wear reduc-tion, particularly when graphite is applied as water based dispersion i.e. TIMREX® LB1300);
• high thermal conductivity (decreases temperature rise due to frictional heating); • electrical conductivity (prevent build-up of static charge which may be a problem in some cases);
• chemically inert (used in conjunction with PTFE in corrosive environments); • high thermal stability (favours use in high temperature applications, e.g. polyimide graphite composites may be used up to 350 °C).
Incorporation of graphite powder into a thermoplastic polymer will generally result in a reduction in the friction coefficient (with the exception of PTFE) but rarely improves the wear resistance. This behaviour is illustrated in the two graphs, which show the mean friction coefficient and specific wear rate for a stainless steel ball (ø = 5 mm) rub-bing on discs of graphite filled polystyrene and polyamide at constant load (32.5 N) and speed (0.03 m/s). The specific wear rates of the graphite-polymer composites were calculated from the diameters of the wear tracks and the contact geometry.
In the case of polystyrene, addition of 30–50% of a high purity macrocrystalline syn-thetic graphite (TIMREX® T75), reduced both friction and wear rate. With polyamide however, addition of a graphite similar to TIMREX® T75 reduced the friction coeffi-cient, but caused a slight increase in the wear rate, with the finer particle size powder (TIMREX® KS6) giving the better result. In the case of low density polyethylene and polypropylene, graphite incorporation causes both an increase in friction and wear.
19
TY
PIC
AL
AP
PLI
CA
TIO
NS
FO
R T
IMR
EX
® G
RA
PH
ITE
AN
D C
OK
E
The results described above are thought to be related to the strength of adhesion at the polymer-graphite interface, which depends upon the wettability of the powder by the molten polymer, powder surface area to volume ratio, surface chemistry, etc. In simple terms, polystyrene shows a strong affinity for the graphite surface, while poly-olefins show a weak affinity. Interfacial adhesion increases with increasing powder surface area to volume ratio, or decreasing particle size.For this reason relatively fine graphite powders (95%<15 microns) are recommended for thermoplastics. The strength of thermosetting polymers is much less sensitive to filler-polymer interactions, therefore coarser graphite powders may be used (typically 95%<75 microns). For thermoplastics, the viscosity of the polymer-graphite melt dur-ing extrusion/moulding will also depend on the graphite particle size, which should be appropriate. Excessive graphite surface area may also lead to void formation in the finished composite, due to desorption of physisorbed vapours in the hot melt.High graphite purity is generally desirable in order to minimize wear, although this param-eter is unlikely to be important in the presence of abrasive fillers (glass fibre, carbon fibre).
Ball/disc friction & wear data: polystyrene/graphite filler
Ball/disc friction & wear data: polyamide 6/graphite filler
Fric
tion
coef
ficie
nt
Spec
ific
wea
r (m
3 /N
m)x
10-1
2
0pure
polystyrene30%
TIMREX® T7550%
TIMREX® T75
2
6
10
8
4
0
0.2
0.1
0.3
0.412 Wear
Friction
Fric
tion
coef
ficie
nt
Spec
ific
wea
r (m
3 /N
m)x
10-1
2
0pure
polyamide30%
TIMREX® KS630%
TIMREX® KS44
5
10
15
0
0.2
0.1
0.3
0.420 Wear
Friction
Influence of graphite addition on the specific wear rate and friction of polystyrene
Influence of graphite addition on the specific wear rate and frictionof polyamide 6
The above mentioned results are the confirmation that TIMREX® graphite powder is an excellent additive to produce self-lubricat-ed polymers. The addition of TIMREX® graphite powder to the unfilled polymers allow for a reduction of the friction coefficient and in most of the cases to a reduction of the wear rate. These results are achieved by a synergic combinations of all the good properties of TIMREX® graphite powder that among the others are: the high degree of crystallinity, the extremely high purity, the optimal texture and the perfect particle size distribution. All of them linked by a common factor: the consistency!
20
TY
PIC
AL
AP
PLI
CA
TIO
NS
FO
R T
IMR
EX
® G
RA
PH
ITE
AN
D C
OK
E
Filled PTFE
Polytetrafluoroethylene (PTFE) exhibits a very low coefficient of friction and retains useful mechanical properties at temperatures from -260 to +260 °C for continuous use. The crystalline melting point is 327 °C, much higher than that of most other semi-crystalline polymers. Furthermore, PTFE is nearly inert chemically and does not adsorb water, leading to excellent dimensional stability. On the one hand, these char-acteristics of PTFE are very useful in the matrix polymer of polymer-based compos-ites which are used in sliding applications. On the other hand, PTFE is subjected to marked cold flow under stress (deformation and creep) and reveals the highest wear among the semicrystalline polymers. However, these disadvantages are very much improved by incorporating suitable fill-ers, allowing the use of PTFE in fields otherwise precluded to this polymer. The treated PTFE is generally known as filled-PTFE. There are many kinds of filled- PTFE composite because various fillers are incorporated into PTFE and one or more materials can be used simultaneously. Usually, these fillers are in form of powders or fibers intimately mixed with the PTFE. The addition of fillers to the PTFE improves or modifies its properties depending upon the nature and quantity of filler: • remarkable increase in wear resistance; • decrease of deformation under load and of creep; • reduction of thermal expansion; • some types of filler increase the thermal and electric conductivity.
Filled PTFE is often not as strong and resilient as virgin PTFE. Sometimes, the fillerlimits the resistance to chemical agents and modify the electrical properties.
TIMREX® PC40-OC cokeTIMREX® PC40-OC coke is calcined at high temperatures offering low sulphur con-centration, low content of oversize particles, high apparent density and high chemi-cal stability against most chemical substances. TIMREX® PC40-OC coke is added to the virgin PTFE in a percentage by weight between 10 and 35% along with small percentage of graphite.Compounds made of PTFE and TIMREX® PC40-OC coke have excellent wear resist-ance and deformation strength and compared to the virgin PTFE, they have practi-cally unchanged chemical resistance and friction behaviour.Typical final materials that can be produced with coke filled PTFE are:engineering design components, slide bearings, valve housing and valve seats for chemi-cal applications, piston sealing and guiding elements for dry-running compressors.
TIMREX® KS44 synthetic graphiteTIMREX® KS 44 is a primary synthetic graphite obtained by the full graphitisation of amor-phous carbon materials through the well known Acheson process. The process param-eters in the Acheson furnace such as temperatures and residential times are all optimised in order to achieve the perfect degree of crystallinity and the lowest level of impurities whereas others minor adjustments are made during the material sizing and conditioning. The percentage of TIMREX® KS44 used in the filled PTFE vary between 5 and 15%. TIMREX® KS44 can be used alone or in combination with glass or coke. TIMREX® KS44 lowers the coefficient of friction and is, therefore, often added to other types of filled PTFE for improving this property (and also to improve the lifetime of the cutting tools during for instance the production of gaskets and seals). It improves the de-formation under load, strength and, to a minor degree the wear. Like coke, it serves well in corrosive environments. PTFE filled with TIMREX® KS44 are often used in steering and shock-absorber gasket, bearings as well as in slide films for anti-static applications.
TIMREX® GRAPHITEAND COKE FILLERS IN FILLED-PTFE
21
TY
PIC
AL
AP
PLI
CA
TIO
NS
FO
R T
IMR
EX
® G
RA
PH
ITE
AN
D C
OK
E
Wear resistanceVirgin PTFE shows much high wear as a result of the destruction of the banded struc-ture due to easy slippage between the crystalline lamellae in the bands.The presence of well distributed carbon particles in the filled PTFE partially avoid the slippage between the crystalline lamellae in the bands and therefore the wear resist-ance is improved.
Deformation strengthVirgin PTFE deformation behaviour is somehow similar to the mechanism previously de-scribed. In someway the deformation phenomena could be explained by the tendency of slippage that occurs between the crystalline lamellae. However, in this case the presence of well distributed carbon particles in the filled PTFE offers only a partial explanation to the phenomena because also hardness of these particles is important in determine an improvement of the deformation behaviour.
Friction coefficientThe coefficient of friction for various filled PTFE composites is weakly dependent upon the incorporated filler, because a thin PTFE film generally exists at the interface between the body and counter-body. Consequently the coefficient of friction is both similar in the filled PTFE and virgin PTFE. This evidence is true as long as no oversize particles are present in the filler. In fact the presence of oversize particles could lead to a radically modification of the coefficient of friction. Because of that in carbons as well as in other fillers is very important the control of oversize particles.
INFLUENCE OF TIMREX®GRAPHITEAND COKE FILLERS IN FILLED-PTFE
22
TY
PIC
AL
AP
PLI
CA
TIO
NS
FO
R T
IMR
EX
® G
RA
PH
ITE
AN
D C
OK
E
The ability of a material to conduct heat is known as its thermal conductivity. Thermal conductivity itself is nothing else than the transportation of thermal energy from high to low temperature regions. Thermal energy within a crystalline solid is conducted by electrons and/or discrete vibrational energy packets (phonons*). Each effect, phon-ons and movement of free electrons, contributes to the rate at which thermal energy moves. Generally, either free electrons or phonons predominate in the system.
*PhononsIn the crystalline structures of a solid material, atoms excited into higher vibrational fre-quency impart vibrations into adjacent atoms via atomic bonds. This coupling creates waves which travel through the lattice structure of a material. In solid materials these lattice waves, or phonons, travel at the velocity of sound. During thermal conduction it is these waves which aid in the transport of energy.
Graphite is an excellent solution for making polymers thermally conductive when elec-trical conductivity is also tolerated. Graphite operates by a phonon collision mecha-nism, very different from the percolation mechanism occurring with metallic powders. This mechanism, together with the particular morphology of graphite particles, helps to meet the required thermal conductivity at lower additive levels without any abrasion issues. In addition, due to its particular structure, thermal conductivity is different in the different directions of the crystal. It is highly conducting along its layers (ab direction or in-plane) and less conducting perpendicular to the layers (c direction or through-plane) because there is no bonding between the layers.In particular, expanded graphite is well known as an excellent thermally and electrically conductive additive for polymers. On the way to graphene, high aspect ratio expanded graphite is thermally more conductive when compared to conventional carbon materi-als such as standard graphite and carbon fibres. However, the very low bulk density of expanded graphite makes it very difficult to feed into a polymer melt using com-mon feeding/mixing technologies. In order to overcome the feed issues encountered by compounders with expanded graphite, Imerys Graphite & Carbon has developed a range of products belonging to the TIMREX® C-THERM™ carbon-based product family.
Thermally conductive polymers
WHAT IS THERMAL CONDUCTIVITY?
THERMAL CONDUCTIVITY OF GRAPHITE
GRADE FEATURES FORM ASH CONTENT (%)
EFFECT ON THERMAL CONDUCTIVITY
TIMREX® KS family Standard (spheroids)
powder < 0.1 medium (through-plane +)
TIMREX® SFG family Standard (flakes)
powder < 0.1 medium (in-plane +)
TIMREX® C-THERM™011 High aspect ratio(pure)
soft granules < 2.5 high
TIMREX® C-THERM™001 High aspect ratio (pure +)
soft granules < 0.3 high
23
TY
PIC
AL
AP
PLI
CA
TIO
NS
FO
R T
IMR
EX
® G
RA
PH
ITE
AN
D C
OK
E
Thermally conductive polymers are able to evenly distribute heat generated inter-nally from a device and eliminate “hot spots.” Possible applications for thermally conductive plastics include heat sinks, geothermal pipes, LED light sockets, heat exchangers, appliance temperature sensors and many other industrial applications. Also thermally conductive elastomers can be found in a wide variety of industrial ap-plications such as gaskets, vibration dampening, interface materials, and heat sinks.As highlighted in the figure, the low thermal conductivity of virgin PPH (~0.38 W/m.K) could be increased by one order of magnitude already at relatively low addition level (~3.5 W/m.K at 20% C-THERM™). The “through-plane” thermal conductivity is about the half of the longitudinal “in-plane” thermal conductivity. These results indicate that the anisotropy of the graphite particles is conferred to the final compound, due to their alignment during the injection molding process. This is an important property that has to be taken into account by design engineers. Of course, the thermal con-ductivity strongly depends not only on the sample orientation (direction) during the measurement, but also on the type of polymer, the sample history (type and condi-tions of compounding and processing) and the measurement method.A full set of measurements to determine mechanical properties in PP were performed and are available to customers. When tested at the same loadings, C-THERM™ im-parts similar mechanical properties as conventional carbon materials.
THERMALLY CONDUCTIVE POLYMERS
Ther
mal
con
duct
ivity
(W/m
.K)
020%
ENSACO®
250G
Virgin PPH 20%TIMREX®
KS25
20%TIMREX®
C-THERM™
1.0
2.0
3.0
3.5
2.5
1.5
0.5
4.0 In-plane
Through-planeIn-planeinj >
Through-plane
24
© 2
01
4 I
me
rys
Gra
ph
ite
& C
arb
on
CH
-Bo
dio
. N
o p
art
of
this
pu
blic
atio
n m
ay b
e r
ep
rod
uce
d in
an
y fo
rm w
ith
ou
t th
e p
rio
r w
ritt
en
au
tho
risa
tio
n.
© 2
01
4 I
me
rys
Gra
ph
ite
& C
arb
on
CH
-Bo
dio
. N
o p
art
of
this
pu
blic
atio
n m
ay b
e r
ep
rod
uce
d in
an
y fo
rm w
ith
ou
t th
e p
rio
r w
ritt
en
au
tho
risa
tio
n.
EUROPE
Imerys Graphite & Carbon Switzerland Ltd. Group Head Office • Strada Industriale 12 • 6743 Bodio • SwitzerlandTel: +41 91 873 20 10 • Fax: +41 91 873 20 19 • [email protected]
Imerys Graphite & Carbon Belgium SABrownfieldlaan 19 • 2830 Willebroek • BelgiumTel: +32 3 886 71 81 • Fax: +32 3 886 47 73 • [email protected]
Imerys Graphite & Carbon Germany GmbHBerliner Allee 47 • 40212 Düsseldorf • GermanyTel: +49 211 130 66 70 • Fax: +49 211 130 667 13 • [email protected]
France Representative Office c/o Imerys154-156 rue de l’Université • 75007 Paris • FranceTel: +33 1 495 565 90/91 • Fax: +33 1 495 565 95 • [email protected]
UK Representative OfficeTel: +44 1 270 212 263 • Fax: +44 1 270 212 263 • [email protected]
ASIA-PACIFIC
Imerys Graphite & Carbon Japan K.K. Tokyo Club Building 13F • 3-2-6 Kasumigaseki • Chiyoda-ku • Tokyo 100-0013 • JapanTel: +81 3 551 032 50 • Fax: +81 3 551 032 51 • [email protected]
Imerys Graphite & Carbon (Changzhou) Co. Ltd. 188# Taishan Road • Hi-Tech Zone • Changzhou 213022 • ChinaTel: +86 519 851 008 01 • Fax: +86 519 851 013 22 • [email protected]
Shanghai Branch Office c/o Imerys 288, Jiu Jiang Road • Hong Yi Plaza • Unit 1102-1105 • Shanghai 200001 • ChinaTel: +86 21 613 782 88 • Fax: +86 21 613 780 02 • [email protected]
Singapore Representative Office c/o Imerys Asia Pacific80 Robinson Road #19-02 • 068898 SingaporeTel: +65 67 996 060 • Fax: +65 67 996 061 • [email protected]
AMERICAS
Imerys Graphite & Carbon USA Inc. 29299 Clemens Road 1-L • Westlake (OH) 44145 • USATel: +1 440 871 75 04 • Fax: +1 440 871 60 26 • [email protected]
Imerys Graphite & Carbon Canada Inc. 990 rue Fernand-Poitras • Terrebonne (QC) J6Y 1V1 • Canada Tel: +1 450 622 91 91 • Fax: +1 450 622 86 92 • [email protected]
Imerys Graphite & Carbon is a trademark of the Imerys Group