Carbon Additives for Polymer Compounds

Polymers

Carbon Additives for
Polymer Compounds

Conductive Carbon Black
Graphite & Coke

www.timcal.com

1

Who are we?

TIMCAL Graphite & Carbon has a strong tra- agement and continuous process improve-
dition and history in carbon manufacturing. Its ment, all TIMCAL manufacturing plants comply
first manufacturing operation was founded in with ISO 9001-2008.
1908. TIMCAL Graphite & Carbon is committed to
Today, TIMCAL facilities produce and market a produce highly specialized graphite and car-
large variety of synthetic and natural graphite bon materials for today’s and tomorrow’s cus-
powders, conductive carbon blacks and water- tomers needs.
based dispersions of consistent high quality. TIMCAL Graphite & Carbon is a member of IMERYS,
Adhering to a philosophy of Total Quality Man- a world leader in adding value to minerals.

Where are we located?

With headquarters located in Switzerland, TIMCAL The Group’s industrial and commercial activities
Graphite & Carbon has an international pres- are managed by an experienced multinational
ence with production facilities and commercial team of more than 430 employees from many
offices located in key markets around the globe. countries on three continents.

HQ Bodio, Switzerland Willebroek, Belgium Lac-des-Îles, Canada Terrebonne, Canada
Graphitization & pro- Manufacturing & pro- Mining, purification and Exfoliation of natural
cessing of synthetic cessing of conductive sieving of natural graphite, processing of
graphite, manufacturing carbon black graphite flakes natural and synthetic
of water-based dispersions, graphite
processing of natural
graphite & coke and
manufacturing & pro-
cessing of silicon carbide

Baotou, China Changzhou, China Fuji, Japan For the updated list of
Purification, intercalation, Manufacturing of Manufacturing of commercial offices and
exfoliation, size reduc- descaling agents and water-based dispersions distributors please visit
tion, shape modification processing of natural www.timcal.com
and sieving & classifying graphite
of natural graphite

What is our vision?
To be the worldwide leader and to be recog-
nized as the reference for innovative capability
in the field of carbon powder-based solutions.

2

Contents

ENSACO® Conductive Carbon Black
TIMREX® Graphite and Coke

Carbon additives for polymer compounds

The products p. 4
p. 5
• Introduction to ENSACO® Conductive Carbon Black p. 6
• Introduction to TIMREX® Graphite and Coke p. 8
• ENSACO® Conductive Carbon Black for polymer compounds
• TIMREX® Graphite and Coke for polymer compounds

Typical applications for ENSACO® Conductive Carbon Black p. 10
p. 14
• Electrically conductive plastics p. 17
• Rubber
• Power cables and accessories

Typical applications for TIMREX® Graphite and Coke p. 18
p. 20
• Self lubricating polymers p. 22
• Filled PTFE
• Thermally conductive polymers

3

the product Introduction to ENSACO® TEM picture of ENSACO® 250 G
Conductive Carbon Black Carbon Black showing the high
level of aggregation.
Conductive carbon blacks are carbon blacks By courtesy of University of
with high to very high stucture (or void volume) Louvain (Louvain-La-Neuve)
allowing the retention of a carbon network at
low to very low filler content. The void volume 100 nm
can originate from the interstices between the
carbon black particles, due to their complex ar- STM picture of the surface of
rangement, and from the porosity. ENSACO® 250 G Carbon Black
5x5 nm.
How ENSACO® Conductive Carbon By courtesy Prof. Donnet - Mulhouse
Blacks are produced
The Timcal carbon black process has been de- SEM picture of ENSACO® 250 G
veloped around 1980 and is commercially ex- Carbon Black illustrating the
ploited since 1982. The plant uses most modern high void volume.
technology. The process is based on partial oil By courtesy of University of
oxidation of carbochemical and petrochemical Louvain (Louvain-La-Neuve)
origin. The major difference with other partial
combustion carbon black technologies lies in 100 nm
the aerodynamic and thermodynamic condi-
tions:
• 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 consistent product
maintaining an outstanding dispersibility. It is in
fact a free-flowing soft flake characterised by a
homogeneous and very low crushing strength
that guarantees 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 conduc-
tive carbon blacks. The unique combination of
high structure and low surface area also con-
tributes to give outstanding dispersibility and
smooth surface finish. The low surface area ma-
terials show a chain-like structure comparable
to acetylene black. The very high surface area
materials 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 rein-
forcement is concerned.
ENSACO® Carbon Blacks combine to a certain
extent both the properties of furnace and acet-
ylene black, reaching the optimal compromise.

4

Introduction to TIMREX®
Graphite and Coke

Graphite finds wide application thanks to its carbon atom and participate in covalent bond- the product
favourable combination of properties such as: ing with three surrounding carbon atoms in the
graphite planes. The fourth electron is located
• low friction, chemical inertness and in the remaining 2p orbital, which projects
absence of inherent abrasiveness; above and below the graphite plane, to form
part of a polyaromatic π-system.
• high thermal conductivity, thermal
stability and electrical conductivity; Delocalisation of electrons in π-electron sys-
tem is the reason of graphite’s high stability
• film forming ability on metal surfaces; and electrical conductivity. Interlamellar bond-
• relatively inoffensive nature of both ing was once thought to be weak and mainly
the result of Van der Waals forces, however, it
powders and products of combustion. now appears that interlamellar bonding is re-
inforced by π-electron interactions. Graphite is
These properties are a consequence of the la- therefore not intrinsically a solid lubricant and
mellar graphite structure and the anisotropic requires the presence of adsorbed vapours to
nature of chemical bonding between carbon maintain low friction and wear.
atoms. In graphite, three sp2 hybrid orbitals
(each containing one electron) are formed
from the 2s and two of the 2p orbitals of each

SEM picture of TIMREX® Graphite showing the perfect c How TIMREX® Graphite and Coke
crystalline structure. c/2 powders are produced

Lc TIMREX® Primary Synthetic Graphite
TIMREX® Primary Synthetic Graphite is pro-
c/2 = Interlayer distance duced in a unique highly controlled graphitiza-
Lc = Crystallite height tion process which assures narrow specifications
and unequalled consistent quality thanks to:
monitoring of all production and processing
stages, strict final inspection, and clearly de-
fined development processes.
TIMREX® Primary Synthetic Graphite shows
unique properties thanks to the combination of
a consistent purity, perfect crystalline structure
and well defined texture.

TIMREX® Natural Flake Graphite
TIMREX® Natural Flake Graphite is produced
in a wide range of products distinguished by
particle size distribution, chemistry and carbon
content. Timcal mines the graphite from its own
source in Lac-des-Îles, Quebec, Canada. Further
processing 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 laboratories to ensure quality,
consistency and total customer satisfaction.

TIMREX® Coke
TIMREX® Petroleum Coke is calcined at appro-
priate temperature with low ash and sulphur
content, well defined texture and consistent
particle size distribution.

5

ENSACO® Conductive Carbon Black
for polymer compounds

Typical values

Property Test Method UNIT ENSACO® 150 G ENSACO® 210 G ENSACO® 250 G ENSACO® 260 G ENSACO® 350 G

Form Granules (*) Granules Granules (*) Granules Granules
55 65 70 770
BET Nitrogen Surface Area m2/g 50
ASTM D3037 155 190 190 320

OAN ml/100 g 165
Absorption
ASTM D2414 (1)

COAN Crushed OAN (1) ml/100 g 95 95 104 104 270
ASTM D2414

Pour Density kg/m3 190 210 170 170 135
ASTM D1513

the product Moisture (as packed) % 0.1 0.1 0.1 0.1 1 max
ASTM D1509 ppm 2
Sieve residue 0.1 2 2 2 10
325 mesh (45 μm) %
ASTM D1514 0.1 0.01 0.01 0.03
Ash Content
ASTM D1506

Volatile Content (2) % 0.2 max 0.2 max 0.2 max 0.2 max 0.3 max
TIMCAL Method 02

Sulphur Content % 0.5 max 0.5 max 0.02 0.02 0.02
ASTM D1619

Toluene Extract % 0.1 max 0.1 max 0.1 max 0.1 max 0.1 max
ASTM D4527

pH 8–11 8–11 8–11 8–11 8–11
ASTM D1512

Volume Resistivity (3) (4) Ohm.cm 2000 max (3) 500 max (3) 10 max (3) 5 max (3) 20 max (4)
TIMCAL Method 11

(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.

6

ENSACO® Conductive Carbon Black
for polymer compounds

Typical effects on polymer compounds

Property ENSACO® 150 G ENSACO® 210 G ENSACO® 250 G ENSACO® 260 G ENSACO® 350 G
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      the product

Water absorption very low very low very low very low high

Surface smoothness     

Electrical/Mechanical     
properties balance
    
Resistance to shear
MRG Easy strippable All polymers
Comments to (Mechanical insulation shields
application domains Rubber Goods)

excellent 
very good 
good 
quite good 
difficult 

(*) ENSACO® 150 and ENSACO® 250 are also available in powder form.

7

TIMREX® Graphite and Coke
for polymer compounds

Typical values

Particle size range Grade Ash Scott density Surface area
d90 (µm) (%) (g/cm3) Bet (m2/g)
Synthetic Graphite KS 6
KS Graphite KS 15 0.06 0.07 26.0
KS 5-25 0.05 0.07 20.0
0 25 50 75 KS 44 0.03 0.23 8.6
KS 5-44 0.06 0.19 9.0
SFG Graphite KS 150 0.02 0.31 5.9
0.06 0.42 3.0
the product 0 25 50 75 150
0.07 0.07 17.0
T Graphite SFG 6 0.07 0.19 5.0
SFG 44 0.03 0.29* 2.5
SFG 150
0.08 0.10 13.0
150 0.07 0.18 10.0
0.07 0.21 9.8
T 15
0 25 50 75 T 44
T 75

150

Natural Graphite

PP Flake PP 10 <5 0.05 10.0
Graphite PP 44 <5 0.11 4.8

0 25 50 75 150 <1 0.08 9.3
<1 0.20 5.4
LSG Flake LSG 10
Graphite LSG 44 <6 0.4* 1.9
<6 0.6* 0.9
0 25 50 75 150

Large flake cumulative size M150
graphite min. 80% <150 mesh (105 µm) 80X150

min. 80% >150 mesh (105 µm)

Coke oversize control PC 40-OC 0.15 0.47* 10.0
PC Coke min. 98% <45 µm (air jet sieving)

max. 0,1% >106 µm (air jet sieving)

Grade Ash Density Particle size Solid content
LB 1300 (%) (g/cm3) distribution (%)
20°C d90 (µm)
0.10
Water-based dispersion 1.17 6.5 27.5
LB Dispersion
Grade Ash Scott density Form d90
Special Grade (%) (g/cm3) (µm)
C-THERM™
C-THERM™001 <0.3 0.15* soft granules 81
* bulk density C-THERM™011 <2.5 0.15* soft granules 81
C-THERM™002 <0.3 0.04* powder
C-THERM™012 <2.5 0.04* powder

8

EnSACo® Conductive Carbon Black
TIMREX® Graphite
for polymer compounds

Conductivity
Targets

9

Typical applications for ENSACO® Conductive Carbon Black Electrically
conductive plastics

The selection of a Some typical final
plastics applications
conductive carbon black • handling of electronic components: carrier
ENSACO® Conductive Carbon Blacks find their
applications in an unlimited number of plastics. boxes, carrier trays, carrier tapes, etc.;
The combination of the polymer type and grade • films: antistatic and conductive films,
and the carbon black grade are determining the
overall electrical and mechanical performance. packaging films, garbage bags, etc.;
The main parameter influencing the final con- • automotive industry: fuel injection systems,
ductivity of a finished part in a given polymer is
the type and level of carbon black used. anticorrosion systems, fuel tank inlet,
The higher the structure of the carbon black, electrostatically paintable parts, etc.;
the lower the level of carbon black needed to • transport: mobile phone parts, wheels,
achieve the required conductivity. Nevertheless, containers, bins, pallets, etc.;
in a minor way, other parameters like the ad- • computer: antistatic articles for computer &
ditives in presence, the compounding or pro- accessories, CD player, etc.;
cessing conditions may also influence the final • health: medical applications, cleanroom
conductivity of parts. equipments, articles for antistatic
Low surface area conductive carbon blacks workplaces, etc.;
show a particular advantage on dispersion and • antistatic flooring;
processing. • heating element;
Percolation curves – correlating the volume re- • sensors;
sistivity and the carbon black percentage – are • PTC switches;
a useful comparative tool to predict the con- • UV protection and pigmentation.
ductivity in place and to select the more appro-
priate system. These curves are valid for a given In the following pages there are some of the re-
formulation and sample preparation technique. sults of experimental work carried out on EN-
The selection of the conductive carbon black SACO® Conductive Carbon Blacks in different
will also influence: polymer compounds.
• the compounding behaviour
The data shown here are given as orientation
(dispersibility, resistance to shear, mixing and are valid for the particular formulations and
cycle, melt flow index, extrusion throughput); sample preparation technique mentioned.
• the surface appearance of the finished mate- Results in other polymers, full studies and pub-
rial (number of surface defects); lications are available upon request.
• the mechanical properties
(polymer property retention, reinforcement);
• the overall price – performance ratio.

The preparation

of a conductive compound
Suitable mixing equipments for the preparation
of black conductive compounds include inter-
nal mixers, twin screw extruders, single screw
kneader machines and LCM. The feeding of low
bulk density, soft flake-type carbon blacks into
extruders requires the use of twin screw feeders
and separate introduction on an already molten
polymer (split feeding technology).

10

EnSACo® ConduCTIvE CARBon BLACkS In HdpE TYpICAL AppLICATIonS FoR EnSACo® ConduCTIvE CARBon BLACk

Influence of the carbon black type on the various carbon blacks in HdpEVolume Resistivity [Ohm.cm] ENSACO® 250 G
resistivity ENSACO® 260 G
109 ENSACO® 350 G
Compounding: laboratory Brabender internal mixer. 107
Processing: compression moulding. 105

The higher the structure of the carbon black,
the lower the percolation threshold.

103

10

0.1 10 20 30 40 50
0 Carbon Black %

At a concentration very near to the percolation Resistivity vs mixing time - 18% carbon black
level, when overmixed, ENSACO® 260 G offers a
higher consistency in resistivity resulting from Volume Resistivity [Ohm.cm] 800 ENSACO® 250 G
its higher shear stability in extreme working 700 ENSACO® 260 G
conditions. 600
500
400 56789 10
300 Brabender Mixing Time [min]
200
100

0
4

At a concentration far above the percolation Resistivity vs mixing time - 25% carbon black
level, both blacks are very stable in resistivity
when overmixed. ENSACO® 260 G shows a con- Volume Resistivity [Ohm.cm] 7.0 ENSACO® 250 G
sistent lower resistivity. 6.5 ENSACO® 260 G
6.0
5.5 56789 10
5.0 Brabender Mixing Time [min]
4.5
4.0
3.5
3.0

4

11

TYpICAL AppLICATIonS FoR EnSACo® ConduCTIvE CARBon BLACk EnSACo® ConduCTIvE CARBon BLACkS In LdpE

Influence of the carbon black type and of the Volume Resistivity [Ohm.cm]various carbon black in LdpE MFI 0.3 and 36 (g/10 min) E250 G LD 0.3
MFI of the starting polymer on the resistivity E250 G LD 36
108 N472 LD 0.3
Compounding: laboratory Brabender internal mixer. 106 N472 LD 36
Processing: compression moulding. P-type LD 0.3
P-type LD 36
The higher the structure of the carbon black, 104
the lower the percolation threshold.
At equal structure, the carbon black of lower 102
surface area gets an advantage on resistivity
that may be coming from the easier dispersion 100 5 10 15 20 25 30 35
resulting in smoother compounding. The higher 0 Carbon Black Concentration [%]
the meltflow index of the starting polymer, the
lower the percolation threshold.

EnSACo® ConduCTIvE CARBon BLACkS In pp

Influence of the carbon black type on the Volume Resistivity [Ohm.cm]ppH MI54 (230 °C/5 kg) with various conductive carbon blacks
resistivity. Relation between resistivity and
melt flow index 104 E250 G
high structure
Compounding and processing: twin screw extruder Haake PTW16 low surface area
and realization of tapes.
103 N472
At same structure level, the carbon black with high structure
the lowest surface area has the smallest impact high surface area
on fluidity reduction.
102

101

100 10 100
0 MFI [230 °C/5 kg] [g/10 min]

Influence of carbon black loading and Volume Resistivity [Ohm.cm] 106 13.50% E250 G
processing on the resistivity 105 4.6E + 10 15% E250 G

Compounding: ZSK25 twin screw extruder. 104
Processing: injection moulding.
103 54
Injection moulding generates more shear than
compression moulding. The closest to the per- 171 10 6
colation, the more visible is that effect. A con- 102
centration safety margin can overcome this
phenomenon. 24

101

100

strands pellets + pressed pellets +
plaques injection moulding

12

EnSACo® ConduCTIvE CARBon BLACkS In pC TYpICAL AppLICATIonS FoR EnSACo® ConduCTIvE CARBon BLACk

Influence of the carbon black type Volume Resistivity [log (Ohm.cm)]volume Resistivity (vR) in function of carbon black loading
on the resistivity
12 ENSACO® 250 G
Compounding: ZSK57 twin screw extruder. 11
Processing: injection moulding. 10 ENSACO® 350 G
9
8
7
6
5
4
3
2
1

5 10 15 20 25

Carbon Black concentration [%]

Influence of the carbon black type on Izod impact strength, notched, in function of vR ENSACO® 250 G
mechanical and rheological performances ENSACO® 350 G
12
Compounding: ZSK57 twin screw extruder. 11Izod [kJ/m2]
Processing: injection moulding. 10
9
Although the concentration for percolation is 8
double the level with ENSACO® 250 G, most 7
mechanical properties are still better. 6
5
4

1 2 3 4 5 6 7 8 9 10 11 12
Volume Resistivity [log (Ohm.cm)]

Tensile Strength for both carbon blacks is almost Tensile strength in function of vR ENSACO® 250 G
at the same level. ENSACO® 350 G

68Tensile Strength [MPa]
67
66
65
64
63
62
61
60

1 2 3 4 5 6 7 8 9 10 11 12
Volume Resistivity [log (Ohm.cm)]

13

Typical applications for ENSACO® Conductive Carbon Black Rubber

Carbon black is one of the main ingredients A few conductive applications:
of any rubber compound. Conductive carbon • belt cover compounds;
blacks are before all carbon blacks, to be mixed • flooring;
and handled as any other reinforcing or semire- • conveyer belts;
inforcing carbon black. They are high structure • hoses for fuel, for conveying of powders, etc.;
materials bulky by nature. Although the com- • cylinder coating;
mon carbon blacks are conductive by nature • shoe soles;
and impart also conductivity to the compounds • seals.
when used in sufficiently high loading, conduc-
tive carbon blacks have the advantage to reach ENSACO® 150 and 250 are also used in non con-
conductivities at lower loading and are often ducting applications where the compounder
used to give the final boost to a compound al- can take profit of the low surface area and high
ready filled with other carbon blacks. As carbon structure of those blacks:
black structure is the parameter determining • low hysteresis with relatively high hardness;
the conductivity, structure being an additive • good thermal aging;
property, the combinations of conductive and • very good tear strength;
normal black can be predicted. • very good dispersion, very good mechani-
Specifications of rubber compounds being usu-
ally quite complex and conductivity being only cal performance at thin layer.
one of the numerous physical requirements, the
use of carbon black blends is very often the A few non-conductive applications:
only solution. In some specific cases, especially • antivibration systems;
in special polymers, it occurs that the conduc- • textile coating;
tive carbon black is used by its own in order to • membranes;
maintain mechanical properties and processing • articles exposed to chipping and chunking.
at a good level.
ENSACO® carbon blacks are, quite close to fur- In the following pages there are some of the re-
nace blacks as far as the reinforcing activity is sults of experimental work carried out on EN-
concerned. Especially the low surface area car- SACO® Conductive Carbon Blacks in different
bon blacks, grades 150, 250 and 260, are, due to rubber compounds.
their very easy dispersion, quite performing in The data shown here are given as orientation
most rubber compounds. ENSACO® 350 is also and are valid for the particular formulations and
used in some compounds where small additions sample preparation technique mentioned. Re-
are required. sults in other polymers, full studies and publica-
tions are available upon request.

14

NBR conductive hose compound Typical applications for ENSACO® Conductive Carbon Black

A B A B

NBR NT 3945 Compound Compound t90% (min) Compound Compound
ENSACO® 250 ENSACO® 250 N-472 Mooney ML (1+4) at 100° C ENSACO® 250 N-472
N-472
N-550 100 100 11.46 11.37
ZnO 25 47.2
Stearic acid 25 45.7
DOP 40 40 72.2
Sulphur 4 4 Vulcanizate data unaged at RT 70.9
Methyl Thuads 0.5 0.5 311
Amax 30 30 Shore A Hardness 339 14.8
0.4 0.4 Stress-strain 13.8 4.6
By courtesy of Bayer 2 2 Elongation at break (%) 3.9 10.3
2 2 Tensile Strength (MPa) 8.6 14.4
Modulus 100% (MPa) 12.6 360
Modulus 300% (MPa) 79 31.8
Modulus 500% (MPa) 32.4
Resistivity (Ohm.cm)
Tear Strength (N/mm)

Conductive CR conveyor belt cover compound

A B A B

Bayprene 610 (CR) Compound Compound Dispersion Rating DIK Compound Compound
Buna CB 10 ENSACO® 250 N-472 t90% (min) ENSACO® 250 N-472
MgO Powder Mooney ML(1+4) at 100°C
N-472 100 100 86.8 85.8
ENSACO® 250 2 2 21.8
Vulkanox DDA 4 4 20.7 64
Vulkanox 4020 30
Ingralen 450 30 62 64
ZnO Powder 1.5 1.5
Rhenogran ETU-80 0.5 0.5 Vulcanizate data unaged at RT 62 540
Stearic acid 15 15 Shore A hardness 22.4
5 5 1.4
By courtesy of Bayer 0.2 0.2 Stress-strain 676 2.7
0.5 0.5 Elongation at break (%) 23.4 11.5
Tensile Strength (MPa) 1.2 20.6
Modulus 50% (MPa) 2.4
Modulus 100% (MPa) 9.2 19
Modulus 300% (MPa) 16.1
Modulus 500% (MPa) 800

Compression Set 24h at 18
70°C (%) 100
Resistivity (Ohm.cm)

15

TYpICAL AppLICATIonS FoR EnSACo® ConduCTIvE CARBon BLACk FkM ConduCTIvE CoMpoundS

12 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
MT black % 127.0 117.0 127.0 137.0 117.0 127.0 137.0 137.0 147.0
E250G % 15.7 0.0 0.0 0.0 0.0 0.0 0.0 14.6 13.6
SCF N-472 % 0.0 8.5 15.7 21.9 0.0 0.0 0.0 7.3 13.6
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

Mooney viscosity ML (1+10’), 100°C 9 t 90% (min)
9
180 20
160 (*) 18 *
140 16
120 14
100 12
80 10
60 8
40 6
20 4
2
0 0
1 2345678
1 2345689
(*) Rejected because uncurable.
Vulcanizate properties at 177°C for 10 min. Compression set (%)

Log Resistivity (ohm.cm) 70
60
14 50
40
12 30
20
10 10

8 0
1 2345689
6

4

2

0
1 234568

Shore A

100
90
80
70
60
50
40
30
20
10

0
1 2345689

16

Power cables and accessories Typical applications for ENSACO® Conductive Carbon Black

Conductive carbon black is used in semicon Typical EVA/NBR strippable compounds
compounds for conductor and insulator shields.
The requirements for those compounds are be- Levaprene 450 Compound Compound Compound
sides processing, a sufficient electrical conduc- N-472 ENSACO® 210 ENSACO® 250
tivity, a smooth or even supersmooth surface Perbunan NT 8625
finish, and high purity. Rhenogran P60 90 90 90
For strippable or easy strippable compounds N-472 10 10
these requirements are added to a specific ad- E 210 10 3 3
hesion strength between the insulating layer E 250 3
and the insulator shield. These strippable or N-550 40 40 40
easy strippable layers have to peeled of by hand Antilux 654 40
or using a specific peeling device. Zn Stearate 40 40 10
Typical polymer compositions are polyolefins or Rhenovin DDA-70 10 10
copolymers; for strippable compounds quite of- Rhenofit TAC/CS 11 1
ten blends of EVA and NBR are used. Percadox BC-408 1.4 1.4 1.4
4.3 4.3 4.3
55 5

Viscosity ML (4+1) 56 44 48
Rheometer@180 t90% 3.6 3.6 3.8
Mechanical properties
Non aged (diff. aged) 16.5 (-19) 16.9 (-15) 16.9 (-15)
Tensile strength MPa 215 (-58) 180 (-50) 170 (-53)
Elongation at break %
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 7 3 4
- after 21 days N 5 4 3
Volume resistivity (Ohm.cm) 5 3 4
210 6600 410

Typical EEA/EBA semicon compounds

EEA Compound Compound
EEA EBA
EBA
E 250 100 100
Peroxide 30
30
Mixing cond. L/D15; Feed BC; Truput 30 5.6
Resistivity @ RT 7.2 22
Resistivity @ 90°C 37 99.4
Carbon black dispersion: <3µm 97.9 239
Die pressure (bar) 229 21.39
MFI (g/10 min) 23.12 0.326
Specific net mixing energy (KWh/kg) 0.313 0
0
Protrusion N°/m2

17

Self lubricating
polymers

Typical applications for TIMREX® Graphite and Coke The choice of a polymer-based self lubricating Graphite powder is widely used in polymer
solid for a particular application depends mainly composites, either alone or in combination with
upon the operating conditions of: temperature, reinforcing fibres, PTFE or various inorganic
chemical environment and the maximum values fillers, e.g. mica, talc (bottom, right table). Ap-
of pressure (p) and sliding speed (v). For each plications include gears, dry sliding bearings,
polymer or composite material, a pv limit is quot- seals, automotive and micro-mechanical parts.
ed, which corresponds to the pressure times the
sliding speed at which the material fails, either The properties of graphite which favour its use
due to unacceptable deformation, or to the high in polymer composites are:
frictional energy dissipated causes surface melt- • low friction lamellar solid
ing, softening and excessive wear.
The pv limit of a polymeric material may be in- (reduces friction);
creased by increasing its mechanical strength • tendency to form a transfer film on the
(resistance to deformation), thermal con-
ductivity (reduction in surface temperatures) countersurface
and by decreasing friction (reduces frictional (assists in wear reduction, particularly when
heating). In practice, thermoplastics (with the graphite is applied as water based dispersion
exception of PTFE) are mainly used as pure i.e. LB 1300);
solids, since their wear resistance and frictional • high thermal conductivity
coefficient, are satisfactory for most applica- (decreases temperature rise due to frictional
tions. Solid lubricant fillers or fibre reinforce- heating);
ment (glass fibres, carbon fibres, textiles) are • electrical conductivity
only employed under the more extreme condi- (prevent build-up of static charge which may
tions of load and speed. be a problem in some cases);
The major polymers employed as self lubricat- • chemically inert
ing solids/composites, are illustrated below. (used in conjunction with PTFE in corrosive
environments);
• high thermal stability
(favours use in high temperature applica-
tions, e.g. polyimide graphite composites
may be used up to 350°C).

18

Incorporation of graphite powder into a ther- Ball/disc Friction & Wear data: polystyrene/graphite filler TYpICAL AppLICATIonS FoR TIMREX® GRApHITE And CokE
moplastic polymer will generally result in a
reduction in the friction coefficient (with the ex- specific wear (m3/Nm)x10-12 12 0.4 wear
ception of PTFE) but rarely improves the wear 10 0.3 friction
resistance. This behaviour is illustrated in the 8 0.2
two graphs, which show the mean friction co- 6 0.1 friction coe cient
efficient and specific wear rate for a stainless 4
steel ball (ø = 5 mm) rubbing on discs of graph- 2 0
ite filled polystyrene and polyamide at constant 0
load (32.5 N) and speed (0.03 m/s). The specific 30% 50%
wear rates of the graphite-polymer composites pure T 75 T 75
were calculated from the diameters of the wear polystyrene
tracks and the contact geometry.
Influence of graphite addition on the specific wear rate and friction of polystyrene
In the case of polystyrene, addition of 30–50%
of a high purity macrocrystalline synthetic specific wear (m3/Nm)x10-12Ball/disc Friction & Wear data: polyamide 6/graphite filler
graphite (T 75), reduced both friction and wear
rate. With polyamide however, addition of a 20 0.4 wear
graphite similar to T 75 reduced the friction friction
coefficient, but caused a slight increase in the
wear rate, with the finer particle size powder 15 0.3
(KS 6) giving the better result. In the case of friction coe cient
low density polyethylene and polypropylene, 10 0.2
graphite incorporation causes both an increase
in friction and wear. 5 0.1

The results described above are thought to be 0 0
related to the strength of adhesion at the pol- pure
ymer-graphite interface, which depends upon 30% 30%
the wettability of the powder by the molten pol- polyamide KS 6 KS 44
ymer, powder surface area to volume ratio, sur-
face chemistry, etc. In simple terms, polystyrene Influence of graphite addition on the specific wear rate and friction of polyamide 6
shows a strong affinity for the graphite surface,
while polyolefins show a weak affinity. Interfa-
cial adhesion increases with increasing powder
surface area to volume ratio, or decreasing par-
ticle size.

For this reason relatively fine graphite pow- The above mentioned results are the confir-
ders (95%<15 microns) are recommended for mation that TIMREX® graphite powder is an
thermoplastics. The strength of thermosetting excellent additive to produce self-lubricated
polymers is much less sensitive to filler-polymer polymers. The addition of TIMREX® graphite
interactions, therefore coarser graphite pow- powder to the unfilled polymers allow for a re-
ders may be used (typically 95%<75 microns). duction of the friction coefficient and in most
For thermoplastics, the viscosity of the poly- of the cases to a reduction of the wear rate.
mer-graphite melt during extrusion/ moulding These results are achieved by a synergic com-
will also depend on the graphite particle size, binations of all the good properties of TIMREX®
which should be appropriate. Excessive graph- graphite powder that among the others are:
ite surface area may also lead to void formation the high degree of crystallinity, the extremely
in the finished composite, due to desorption of high purity, the optimal texture and the perfect
physisorbed vapours in the hot melt. particle size distribution. All of them linked by
a common factor: the consistency!
High graphite purity is generally desirable in or-
der to minimize wear, although this parameter
is unlikely to be important in the presence of
abrasive fillers (glass fibre, carbon fibre).

19

Filled PTFE

Typical applications for TIMREX® Graphite and Coke Polytetrafluoroethylene (PTFE) exhibits a very TIMREX® Graphite
low coefficient of friction and retains useful me- and Coke fillers in filled-PTFE
chanical properties at temperatures from -260
to +260 °C for continuous use. TIMREX® PC 40-OC Coke
The crystalline melting point is 327 °C, much TIMREX PC 40-OC Coke is calcined at high tem-
higher than that of most other semi-crystalline peratures offering low sulphur concentration,
polymers. Furthermore, PTFE is nearly inert low content of oversize particles, high apparent
chemically and does not adsorb water, leading density and high chemical stability against most
to excellent dimensional stability. On the one chemical substances. TIMREX® PC 40-OC Coke
hand, these characteristics of PTFE are very is added to the virgin PTFE in a percentage by
useful in the matrix polymer of polymer-based weight between 10 and 35% along with small
composites which are used in sliding applica- percentage of graphite.
tions. On the other hand, PTFE is subjected to Compounds made of PTFE and TIMREX® PC
marked cold flow under stress (deformation 40-OC Coke have excellent wear resistance
and creep) and reveals the highest wear among and deformation strength and compared to the
the semicrystalline polymers. virgin PTFE, they have practically unchanged
However, these disadvantages are very much chemical resistance and friction behaviour.
improved by incorporating suitable fillers, al- Typical final materials that can be produced
lowing the use of PTFE in fields otherwise pre- with coke filled PTFE are:
cluded to this polymer. engineering design components, slide bearings,
The treated PTFE is generally known as filled- valve housing and valve seats for chemical ap-
PTFE. There are many kinds of filled- PTFE plications, piston sealing and guiding elements
composite because various fillers are incorpo- for dry-running compressors.
rated into PTFE and one or more materials can
be used simultaneously. Usually, these fillers are TIMREX® KS44 Synthetic Graphite
in form of powders or fibers intimately mixed NTIMREX® KS 44 is a Primary Synthetic Graph-
with the PTFE. ite obtained by the full graphitisation of amor-
The addition of fillers to the PTFE improves or phous carbon materials through the well known
modifies its properties depending upon the na- Acheson process. The process parameters in the
ture and quantity of filler: Acheson furnace such as temperatures and resi-
• remarkable increase in wear resistance; dential times are all optimised in order to achieve
• decrease of deformation under load and of the perfect degree of crystallinity and the lowest
level of impurities whereas others minor adjust-
creep; ments are made during the material sizing and
• reduction of thermal expansion; conditioning.
• some types of filler increase the thermal and The percentage of TIMREX® KS 44 used in the
filled PTFE vary between 5 and 15%.
electric conductivity. TIMREX® KS 44 can be used alone or in combina-
tion with glass or coke.
Filled PTFE is often not as strong and TIMREX® KS 44 lowers the coefficient of friction
resilient as virgin PTFE. Sometimes, the filler and is, therefore, often added to other types of
limits the resistance to chemical agents and filled PTFE for improving this property (and also
modify the electrical properties. to improve the lifetime of the cutting tools dur-
ing for instance the production of gaskets and
seals). It improves the deformation under load,
strength and, to a minor degree the wear. Like
coke, it serves well in corrosive environments.
PTFE filled with TIMREX® KS 44 are often used in
steering and shock-absorber gasket, bearings as
well as in slide films for anti-static applications.

20

Influence of TIMREX®Graphite Typical applications for TIMREX® Graphite and Coke
and Coke fillers in filled-PTFE

Wear resistance
virgin PTFE shows much high wear as a result of
the destruction of the banded structure due to
easy slippage between the crystalline lamellae
in the bands.
The presence of well distributed carbon parti-
cles in the filled PTFE partially avoid the slip-
page between the crystalline lamellae in the
bands and therefore the wear resistance is im-
proved.

Deformation strength
virgin PTFE deformation behaviour is somehow
similar to the mechanism previously described.
In someway the deformation phenomena could
be explained by the tendency of slippage that
occurs between the crystalline lamellae. How-
ever, 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 Coefficient
the coefficient of friction for various filled PTFE
composites is weakly dependent upon the in-
corporated filler, because a thin PTFE film gen-
erally 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 over-
size particles.

21

Thermally
conductive polymers

Typical applications for TIMREX® Graphite and Coke What is thermal conductivity? Thermal conductivity
The ability of a material to conduct heat is known
as its thermal conductivity. Thermal conductiv- of graphite
ity itself is nothing else than the transportation Graphite is an excellent solution for making
of thermal energy from high to low tempera- polymers thermally conductive when electri-
ture regions. Thermal energy within a crystalline cal conductivity is also tolerated. Graphite
solid is conducted by electrons and/or discrete operates by a phonon collision mechanism,
vibrational energy packets (phonons*). Each ef- very different from the percolation mechanism
fect, phonons and movement of free electrons, occurring with metallic powders. This mecha-
contributes to the rate at which thermal energy nism, together with the particular morphology
moves. Generally, either free electrons or phon- of graphite particles, helps to meet the re-
ons predominate in the system. quired thermal conductivity at lower additive
levels without any abrasion issues. In addition,
*Phonons due to its particular structure, thermal con-
In the crystalline structures of a solid mate- ductivity is different in the different directions
rial, atoms excited into higher vibrational fre- of the crystal. It is highly conducting along
quency impart vibrations into adjacent atoms its layers (ab direction or in-plane) and less
via atomic bonds. This coupling creates waves conducting perpendicular to the layers (c dir-
which travel through the lattice structure of a ection or through-plane) because there is no
material. In solid materials these lattice waves, bonding between the layers.
or phonons, travel at the velocity of sound. In particular, expanded graphite, is well known
During thermal conduction it is these waves as an excellent thermally and electrically con-
which aid in the transport of energy. ductive additive for polymers. On the way to
graphene, high aspect ratio expanded graph-
ite is thermally more conductive when com-
pared to conventional carbon materials 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 common feeding/mixing technolo-
gies. In order to overcome the feed issues en-
countered by compounders with expanded
graphite, TIMCAL has developed a range of
products belonging to the TIMREX® C-THERM™
carbon-based product family.

Grade Features Form Ash Effect on
powder content (%) thermal conductivity
TIMREX®KS family Standard powder < 0.1 medium
TIMREX®SFG family (spheroids) soft granules (through-plane +)
TIMREX®C-THERM™011 Standard soft granules < 0.1 medium
TIMREX®C-THERM™001 (flakes) (in-plane +)
High aspect ratio < 2.5 high
(pure)
High aspect ratio < 0.3 high
(pure +)

22

THERMALLY ConduCTIvE poLYMERS ing the measurement, but also on the type of
Thermally conductive polymers are able to polymer, the sample history (type and condi-
evenly distribute heat generated internally tions of compounding and processing) and the
from a device and eliminate “hot spots.” Pos- measurement method.
sible applications for thermally conductive A full set of measurements to determine me-
plastics include heat sinks, geothermal pipes, chanical properties in PP were performed and
LED light sockets, heat exchangers, appliance are available to customers. When tested at the
temperature sensors and many other industrial same loadings, C-THERM™ 001/011 imparts
applications. Also thermally conductive elas- similar mechanical properties as conventional
tomers can be found in a wide variety of in- carbon materials.
dustrial applications such as gaskets, vibration Thermal Conductivity [W/m.K]
dampening, interface materials, and heat sinks. 4.0 In-plane In-plane
As highlighted in the figure, the low thermal 3.5 inj > TYpICAL AppLICATIonS FoR TIMREX® GRApHITE And CokEThrough-planeThrough-plane
conductivity of virgin PPH (~0.38 W/m.K) 3.0
could be increased by one order of magni- 2.5 20% 20% 20%
tude already at relatively low addition level 2.0 ENSACO® TIMREX® TIMREX®
(~3.5 W/m.K at 20% C-THERM™). The “through- 1.5 C-THERM™
plane” thermal conductivity is about the half of 1.0 250G KS25
the longitudinal “in-plane” thermal conductiv- 0.5
ity. These results indicate that the anisotropy
of the graphite particles is conferred to the 0
final compound, due to their alignment dur- Virgin PPH
ing the injection molding process. This is an
important property that has to be taken into
account by design engineers. Of course the
thermal conductivity strongly depends not
only on the sample orientation (direction) dur-

Timcal locations

production plants
Commercial offices
Distributors present in
many countries. For the
updated list please visit
www.timcal.com

23

EUROPE Asia-Pacific Americas

TIMCAL Ltd. TIMCAL Japan K.K. TIMCAL America Inc. © 2012 TIMCAL Ltd., CH-Bodio. No part of this publication may be reproduced in any form without the prior written authorisation of TIMCAL Ltd.
Group Head Office Tokyo Club Building 13F 29299 Clemens Road 1-L
6743 Bodio 3-2-6 Kasumigaseki, Westlake (OH) 44145
Switzerland Chiyoda-ku USA
Tel: +41 91 873 20 10 Tokyo 100-0013 Tel: +1 440 871 75 04
Fax: +41 91 873 20 19 Japan Fax: +1 440 871 60 26
[email protected] Tel: +81 3 551 032 50 [email protected]
Fax: +81 3 551 032 51
TIMCAL Belgium NV/SA [email protected] TIMCAL Canada Inc.
Appeldonkstraat 173 990 rue Fernand-Poitras
2830 Willebroek Changzhou TIMCAL Terrebonne (QC) J6Y 1V1
Belgium Canada
Tel: +32 3 886 71 81 Graphite Corp. Ltd. Tel: +1 450 622 91 91
Fax: +32 3 886 47 73 188# Taishan Road Fax: +1 450 622 86 92
[email protected] Hi-Tech Zone [email protected]
Changzhou 213022
TIMCAL Deutschland GmbH China
Berliner Allee 47 Tel: +86 519 851 008 01
40212 Düsseldorf Fax: +86 519 851 013 22
Germany [email protected]
Tel: +49 211 130 66 70
Fax: +49 211 130 667 13 Changzhou TIMCAL
[email protected]
Graphite Corp. Ltd.
France Representative Office
c/o IMERYS Shanghai Branch Office
154-156 rue de l’Université
75007 Paris, c/o IMERYS (Shanghai)
France 288, Jiu Jiang Road
Tel: +33 1 495 565 90/91 Hong Yi Plaza
Fax: +33 1 495 565 95 Unit 1102-1105
[email protected] Shanghai 200001
China
UK Representative Office Tel: +86 21 613 782 88
Tel: +44 1 270 212 263 Fax: +86 21 613 780 02
Fax: +44 1 270 212 263 [email protected]
[email protected]
Singapore Representative Office

c/o IMERYS Asia Pacific (Singapore)
80 Robinson Road #19-02
068898 Singapore
Tel: +65 67 996 060
Fax: +65 67 996 061
[email protected]

www.timcal.com

24