New Silicone Copolymer Lubricants - the alternative to PFPE lubrication

Outline of presentation
• Polysiloxanes: Structure and Properties
• Phenyl / Fluoro Siloxane Copolymer Lubricants
– Structure
– Properties
– Additive acceptance
– Greases
• Applications
• Summary
2

Polysiloxanes: Structure and Properties
Silicone or Polysiloxanes (IUPAC) are chain polymers with a
Si-O-Si backbone:
3
They have some unique properties like:
High thermal stability High oxidative stability
Chemically inert Low vapor pressure
Low surface tension

Polysiloxanes: Structure and Properties
4
Dimethyl
Silicone
“Standard” silicones H3C –Si – O – Si – O — Si – O – CH3
CH3 CH3
n
CH3
CH3CH3CH3
Phenyl
Methyl
Silicone
Additional thermal
and oxidation stability
H3C –Si – O – Si – O — Si – O – CH3
CH3 CH3
n
CH3
CH3C6H5CH3
Fluorosilicone
Better load-carrying capacity
and wear resistance
Excellent chemical
resistance H3C –Si – O – Si – O — Si – O – CH3
CH3 CH3
n
CH3
CH3
CH2
CH3
CH2
CF3

– Structure
– Properties
– Greases
• Applications
• Summary
5

Structure of Phenyl / Fluoro Siloxane
Copolymer Lubricants
6
FluoroPhenyl
Thermal stability Wear resistance
Phenyl / Fluoro Copolymer
Different Ph/F ratio allowes to
ballance between thermal stability
and wear resistance

Properties – Thermal Stability
7
• Samples stored in
an oven at 250°C
• Viscosity measured
weekly / biweekly
until gelling
Sample with high phenyl
content (75:25) has best
thermal / oxidation
stability
Open cup allows evaporation of fluid

Properties – Thermal Stability
8
• Samples stored in
an oven at 250°C
• Viscosity measured
weekly / biweekly
• All ratios behave
similarly
• Slight viscosity
decrease
Closed cup prevents evaporation of fluid

Properties – Viscosity
9
Temperature
(°C)
Viscosity
(mPas)
-30 607300
-20 88000
-10 20500
0 6300
10 2650
20 1380
30 780
40 480
50 330
60 230
70 170
80 130
90 95
100 80
110 65
120 55
Ph/F ratio
50:50
Fluid density: 1.15 – 1.20 g/cm3

Properties – Comparison
10
Fluid Ph/F
75:25
Ph/F
50:50
Ph/F
25:75
PAO
40
Polyol-
ester
Silicone
fluids
(PMPS)
Fluoro-
silicone
PFPE
(branched)
PFPE
(linear)
Viscosity (40°C),
mPas
408 328 314 345 171 244 188 80 cSt 159 cSt
Viscosity Index 229 239 242 155 145 220 241 108 338
TGA (250°C) 98,6% 99,0% 99,0% 97,4% 96,5% 99,1% 97,2% 93,4% 99,3%
DSC (onset
temperature)
282°C 283°C 277°C 205°C 203°C 366°C 246°C 348°C 330°C
Evaporation
(200°C, 7d)
0,13% 0,47% 0,65% 7,85% 13,38% 1,46% 18,50%
Not
tested
Not
tested
TGA and DSC: 30-500°C, 10°C/min, air 60ml/min
Evaporation: internal test method (open cups in oven)
• Viscosity indices 230 – 250
• DSC onset temperatures > 270°C
• Low evaporation

Properties – Wear Resistance of Neat Fluids
11
Fluid Ph/F ratio 400 N load 800 N load
Average wear scar diameter
Phenyl / Fluoro Siloxane
Copolymer
75:25 1,53 mm
Not
measureable
50:50 1,48 mm 2,82 mm
25:75 0,55 mm 1,81 mm
Polyphenylmethylsiloxane Not measurable
Fluorosilicone 1,18 mm 1,17 mm
4-ball wear scar test (DIN 51350-3)
• 400 N load typically too high for Phenyl-Si-fluids
• Copolymer fluids are able to generate results
• The higher the fluoro content the smaler the wear scars

Properties – Wear Resistance of Neat Fluids
12
T = 50°C
Freq.= 50 Hz
Load = 300 N
Stroke = 2 mm
Cylinder / Plate
Phenylmethyl-
polysiloxane
fluids are not
measureable
(300 N)

Additive Acceptance
13
Polysiloxane fluids have
limited miscibility with
additives
Fluorosiloxane fluids are
immiscible with additives
Phenyl / Fluoro copolymer fluids show good
acceptance with many commercial available additives
New lubricants using commercial available additives

Wear Resistance Improvements by Additives
14
Additivation Chemistry % 400 N load 800 N load
average wear scar diameter
(change compared to particular neat fluids)
antimony
o,o-dialkylphoshorodithionate
2,5% 0,55 mm (-69%) 1,03 mm (-59%)
zinc diamyldithiocrbamate 2,5% 0,51 mm (-71%) 1,07 mm (-57%)
dithiocarbamate, ashless
1,0% 0,66 mm (-55%) 1,29 mm (-54%)
2,5% 0,62 mm (-58%) 1,16 mm (-59%)
dialkylpentasulfide
1,0% 0,65 mm (-56%) 1,98 mm (-30%)
2,5% 0,82 mm (-45%) 2,07 mm (-27%)
zinc dialkyldithiophosphate
1,0% 0,76 mm (-49%) 1,21 mm (-57%)
2,5% 0,66 mm (-55%) 1,16 mm (-59%)
amine alkylisooctylphosphate 1,0% 1,48 mm (± 0%) 1,89 mm (-33%)
Wear resistance improvements of about 50% compared to pure fluids

Copolymer Greases
15
• Greases can be prepared by using single and complex thickener
systems. For example Li- and Li-complex soaps
• Non soap thickerners like polyurea or PTFE are also suitable to
prepare copolymer greases
Grease preparation process is similar to
current polysiloxane greases

Li-complex Grease (50:50 Ph/F ratio)
16
Characteristic Test
method
Value
Penetration
(unworked / 60 / 10k / 100k
strokes)
DIN ISO
2137
258 / 261 / 282 /
303
Base oil viscosity (40°C) 246 mPas
Bleed / Evaporation
(24h / 200°C)
ASTM
D 6184
0,46% / 1,17%
Dropping point IP 396-2 340°C
Flow pressure (-35°C) DIN 51805 925 mbar
Emcor corrosion
(7d, dist. water)
DIN 51802 0
Water resistance (3h, 90°C) DIN 51807 1
DIN 4 ball test (ok-load) DIN 51350 1700 N*
DIN 4 ball test
(wear scar, 400 N, 1h)
DIN 51350 1,05 mm
* Outside DIN measurement range

PTFE grease (50:50 Ph/F ratio)
17
Characteristic Test
method
PTFE
grease A
PTFE
grease B
Additivation No additives Additives
Penetration
(unworked / 60 / 100k strokes)
DIN ISO
2137
324 / - / -
290 / 290 /
296
Base oil viscosity (40°C) 790 mPas 460 mPas
Bleed / Evaporation
(24h / 200°C)
ASTM
D 6184
4,58% / 0,44% 3,67% / 0,33%
Dropping point IP 396-2 332°C 285°C
Flow pressure (-40°C) DIN 51805 1125 mbar 950 mbar
Emcor corrosion
(7d, dist. water)
DIN 51802 4 0
Water resistance (3h, 90°C) DIN 51807 0 0
DIN 4 ball test (ok-load) DIN 51350 1900 N* 2300 N
DIN 4 ball test
(wear scar, 400 N, 1h)
DIN 51350 1,02 mm 1,18 mm
FE9 (B, 6000rpm, 1500N, 220°C)
F50 value
DIN
51821-2
69h 63h
* Outside DIN measurement range

– Structure
– Properties
– Greases
• Applications
• Summary
18

Applications of Siloxanes as Lubricants
19
Dimethyl
Silicone
• O-ring and valve lubricants
• Damping grease
• Plastic gears
• Brake caliper
Phenyl Methyl
Silicone
• Overrunning clutch
• Clutch release bearing
• Bearings operating at
low temperatures
Fluorosilicone
• Chemical mixers and pumps
• O-rings or gaskets exposed
to aggressive chemicals
• Brake compressor
• Plug valves
• Circuit breakers
Phenyl-
Fluoro-
silicone
• High-temperature applications (corrugators bearings, oven chains,
automotive powertrain components...)
• Wide service temperature applications (-35°C to +220°C)

– Structure
– Properties
– Greases
• Applications
• Summary
20

Summary
21
• Phenyl- Fluoro- copolymer siloxane fluids are a totally new
class of lubricating polysiloxane fluids that opens new
opportunities and possibilities
• Their flexible structure allows to design fluids with high
thermal stability and improved wear resistance properties
• Ph/F copolymer fluids have an improved additive acceptance
which allows to create lubricants for a broad range of
applications.
• Copolymer greases are available with different kind of
thickener systems
• PTFE copolymer greases show excellent thermal resistance at
applications running at high temperatures (>200°C)

Acknowledgement
22
• Vesna Weber
• Aleksandra Nevskaya
• Dr. Manfred Jungk
• Dr. Detlev Hesse
• Dr. Michael Schütz
• Molykote® laboratory and testfield team

THANK YOU!

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24

New Silicone Copolymer Lubricants - the alternative to PFPE lubrication

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