Dave Lawson IRC 2009 Presentation

Dow Corning PROPRIETARY

Recent Innovations in Fluorosilicone Rubber (FSR)

IRC 2009, NurembergDave Lawson, Dow Corning

co-authors:Marco Pagliani, Emmanuel Bravais, Craig Gross, Lauren Tonge, Fabien Virlogeux, Bruno Cuocci, Hans Peter Wolf


Objective of Today’s Presentation• To review recent developments in fluorosilicone rubber (FSR)

and highlight the growing potential for this class of material

1. A multigenerational approach to upgrade our high consistency FSR for use as high temperature turbocharger hose liner• Temperature Resistance up to 200-225C• Oil Resistance• Interlayer Adhesion and Adhesion Stability

2. New family of liquid FSR (Silastic® F-LSR) that achieves typical FSR chemical resistance in an injection moldable delivery form• Fabrication of intricate parts• Fast cycle time with low scrap rates


Introduction to Fluorosilicone and Fluorosilicone Rubber (FSR)*

* FSR and FVMQ are used interchangeably


What is a Fluorosilicone

• Replacing one of a silicone’s methyl groups with trifluoropropyl results in the following:

– Improved resistance to non-polar hydrocarbon fuels, oils, and solvents– Increased specific gravity– Lower refractive index– Improved solubility in polar fluids such as esters and ketones– Improved lubricity– Lower use temperature by eliminating polymer Tm crystallization

-O-Si-O-

CH3

CH3

--

-O-Si-O-

CH3

CH2CH2CF3

--


Why Use a Fluorosilicone Rubber

• FSR maintains the extreme temperature resistance of conventional silicone rubber (VMQ), now with additional levels of chemical resistance

• FSR is therefore uniquely suited to a variety of automotive applications that require elastomeric components to survive increasingly harsh conditions

Very HotVery Cold

AggressiveFluids

Very HotVery Cold

AggressiveFluids


Part 1

Recent Developments in High Consistency FSR for Turbocharger

Hose Applications


High Consistency Silicone Rubber (HCR) is now well established to satisfy the high temperature requirements for “hot side” hoses

Hose liner can be either Fluorosilicone Rubber (FSR) or Fluorocarbon (FKM)

Liner needs to provide oil barrier properties, resistance to extremes of temperature, plus long lasting functional performance & hose integrity

Fluoroelastomer liner(for oil resistance)

Aramid fabric (reinforcement)

HCRMedium layer

HCROuter layer


Key Performance Requirements

• Temperature Resistance• Oil Resistance• Interlayer Adhesion and Adhesion Stability• Processing Characteristics

Calendering Co-extrusion


Temperature Resistance & Trends• Under the bonnet temperatures are increasing• Continuous use temperatures have increased from 175C

200C 225C and higher– Euro IV, V, VI …– Small trucks in US market (US EPA 2007, 2010)

• Peak temperatures of 250C are now common• Formulation expertise is very important in order to

achieve the highest levels of temperature resistance• Our optimised FSR formulations show excellent property

retention after relevant heat ageing• FSR in general shows superior property retention

compared to FKM when measured at typical service temperatures


Heat Ageing - 42 Days @ 200C

• Under these conditions we have been able to reduce the loss in tensile strength to around 10-25%

• Changes in elongation at break are in the range 35-45%• Actual (retained) values of elongation after this heat exposure are

typically between 150% and 220%

Property Retention - 42 Days Heat Ageing @ 200C

0102030405060

HT1 HT2 HT3 HT4 HT5 HT6

Formulation

% C

hang

e in

Pro

perty

% loss in tensilestrength

% loss in elongation atbreak


Heat Ageing – 7 Days @ 225C

• Similar trends are observed compared to continuous test at 200C; stability in general is improved with this combination of higher temperature/shorter time

• Tensile strength changes are typically ~ 10% or lower• Elongation at break changes can be as low as 25% (especially

formulations HT1, 2 and 3)

Property Retention - 7 Days Heat Ageing @ 225C

0

10

20

30

40


Formulation

% C

hang

e in

Pro

perty

% loss in tensilestrength



Peak Temperature Testing from 225C-250C

• Trends are very clear as the severity of this test increases• Even at 250C we retain around 60% of our starting tensile strength

and 55% of original elongation at break• 250C peak temperature represents continuous exposure to 225C• Materials are competitive for continuous hose temperatures of ~ 225C

Property Retention - 7 Day Testing at Peak Temperatures (Formulation HT2)

010

2030

4050

225C 230C 240C 250C

Peak Temperature

% C

hang

e in

Pr

oper

ty % loss in tensilestrength

% loss in elongationat break


Alternative View: Measure Properties @ Service Temperature

• Room temperature values of > 400% EB are achievable with FSR• FSR @ 180C can still maintain 200-300% EB• FKM @ 180C shows < 100% EB

Elongation at Break as Measured @ 180C

0100200300400500

FSR # 1

FSR # 5

FSR # 6

FSR # 7

FKM Ref

AEM Ref

Material

% E

long

atio

n @

Bre

ak

E.B. @ Room Temp

E.B. @ 180C


Oil Resistance• Hose liner must act as a barrier layer to prevent oil weep

into subsequent layers and degradation of the hose• Typical testing involves immersion in hot oil and

measurement of change in mechanical properties• Test temperatures are trending upwards (150C 175C

200C)• Oils are becoming more aggressive due to their fully

synthetic nature and additive packages– Engine wear is reduced– Service intervals are increased– Elastomeric components are challenged to survive!

• Our preferred test oil has been LUB MA4 5w30


Oil Resistance – 7 Days @ 175C

• This latest range of optimised formulations demonstrates exceptionally low property changes in this oil immersion test

• Loss in tensile strength can be controlled down to 10-15%• Best materials exhibit loss in elongation at break of 10-20%

Property Retention - 7 Days Oil Ageing @ 175C in pre-aged MA4

01020304050


Formulation

% C

hang

e in

Pr

oper

ty % loss in tensilestrength



Interlayer Adhesion and Heat Stability

• We have developed novel adhesion promoter chemistry that achieves good initial adhesion, but also excellent stability

• Initial peel strength of 2 N/mm is considered acceptable• Ageing of an FVMQ-VMQ composite @ 200C shows 5% loss in initial

bond strength after 24 hours and just 50% loss after 1 month• FKM-VMQ composite shows much higher adhesion loss

Adhesion Stability @ 200C

0

1

2

3

4

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Days

Peel

Str

engt

h (N

/mm

)

FSR-HCR

FKM-HCR


Processing Characteristics• FSR has many attributes that are well matched with the

needs in this application• Wide range of hardness both calendering and co-

extrusion are possible to yield thin and therefore cost effective layers Co-extrusion simpler and more compact hose designs Calendering more complex, convoluted and larger

diameter hoses• Similarity between FSR and HCR (chemical nature of

siloxane backbone, cure chemistry, cure speed)


Conclusions from PART 1• We have been able to deliver multigenerational FSR improvements

to meet the increasing challenges of turbocharger hose applications• We strongly believe in the all round superiority and sustainability of

an FSR-HCR solution for this fast growing segment, given the established and/or upgraded performance in the following areas:

Resistance to increasing temperatures Resistance to modern, synthetic, aggressive engine oils Interlayer adhesion and adhesion stability Low temperature performance and flexibility Chemical and physical compatibility between FSR and HCR Processing efficiencies fast throughput & low levels of waste Wide range of hardness materials are compatible with fabrication

via both calendering and co-extrusion techniques


Part 2

A New Product Line of Liquid FSR (Silastic® F-LSR)


Overview• We are commercializing a new product line of liquid F-

LSR, including our first 100 mol% F-LSR materials• These products offer similar chemical resistance to

traditional high consistency FSR, combined with lower viscosity and processability of an LSR

• An upgraded range of 40 mol% F-LSR copolymers is also available; this copolymer approach already offers enhanced performance compared to a silicone rubber

• New design possibilities are now enabled thanks to the existence of FSR in a genuinely liquid form


Product Line

• Copolymers (40 mol%) are available in 45 Shore and 65 Shore• 100 mol% materials are currently available in 30 Shore and 40 Shore

versions

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100

Mol % Trifluoropropyl Methyl

Dur

omet

er FL 65-9001

FL 45-9001FL 40-9201FL 30-9201

Dim

ethy

lLS

Rs

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100

Mol % Trifluoropropyl Methyl

Dur

omet

er FL 65-9001

FL 45-9001FL 40-9201FL 30-9201

Dim

ethy

lLS

Rs

Copolymers (40 mol%) 100 mol% F-LSRs

Silicone Rubber


General Characteristics All these F-LSR materials offer the following capabilities:

No post cure potential Lower use temperature by elimination of polymer melt point Wide range of temperature stability Good mechanical properties for excellent performance

The new Silastic® 100 mol% F-LSRs offer further significant benefits:

Excellent resistance to non-polar hydrocarbon fuels, oils, and solvents

Improved solubility in polar fluids such as esters and ketones Same fluid resistance as standard high consistency FSR grades


Volume Swell Performance

• Data shows the very good swell resistances achieved over extended testing times

• Note particularly the performance in aggressive diesel type fluids• Good mechanical properties were retained throughout the ageing tests,

especially for the two Silastic® 100 mol% F-LSRs• The effect of fluorine substitution is evident in the lower swell for the

100 mol% materials

-2

0

2

4

6

8

10

FL 30-9201 FL 40-9201 FL 45-9001 FL 65-9001

Volu

me

Swel

l

MA4 7d/175C SLX 0W30 3d/150C SLX 0W30 500hrs/150C

IRM 903 72hrs/150C FAME Biodiesel 3d/40C Diesel 3d/40C


Uncompressed Permeation in CE10 @ 60C

• Data shows results from permeation cup testing• Test used CE10 (Reference Fuel C with 10% Ethanol) at 60C• The performance of the copolymer is already significantly better than

the dimethyl HCR• Silastic® 100 mol% liquid F-LSR and a traditional high consistency

FSR give very similar results (and dramatically lower than the copolymer offerings)

05,000

10,00015,00020,00025,00030,00035,00040,00045,000

HCR(VMQ)

CopolymerF-LSR

FSR(FVMQ)

FL 40-9201

Perm

eatio

n R

ate

(gm

*mm

/m2*

day)


Blow By Testing using FL 30-9201BMW Specification GS 97018 : 2001-11Fluid 1

72 h 120°C Drying : 2 h 23°C + 24 h 60°C + 24 h 80°C + 24 h 120°C

Test Unit Norm Value Change Value Change

Wet status After drying

Hardness Shore A DIN 53505-A 21 -12pts 44 +11 pts

Tensile N/mm2 DIN 53504 S2 3.5 -49% 6.8 0%

Elongation % DIN 53504 S2 290 -25% 298 -23%

50 % modulus N/mm2 DIN 53504 S2 0.33 -30% 0.76 +62%

100% modulus N/mm2 DIN 53504 S2 0.71 -26% 1.54 +60%

weight change % 7.5 -2.3

volume change % 14.8 -2.2

• Very good retention of elastomeric properties with 100 mol% F-LSR• Elongation at break still ~ 300%• Relatively low volume swell, even at wet stage


Blow By Testing using FL 30-9201BMW Specification GS 97018 : 2001-11Fluid 2

72 h 120°C

Drying : 2 h 23°C + 24 h 60°C + 24 h 80°C + 24 h 120°C

Test Unit Norm Value Change Value Change

Wet status After drying

Hardness Shore A DIN 53505-A 34 1pts 37 +4 pts

Tensile N/mm2 DIN 53504 S2 6.7 -1.5% 7.4 9%

Elongation % DIN 53504 S2 402 +4.4% 382 -0.8%

50 % modulus N/mm2 DIN 53504 S2 0.5 +6.4% 0.55 +17%

100% modulus N/mm2 DIN 53504 S2 0.97 1% 1.11 +16%

weight change % 1.8 -0.5

volume change % 2.6 -0.5

• Exceptional stability to aqueous/acidic environment• Volume changes very low• Elongation at break virtually unaffected


Selected Features/Benefits

• Processable via Injection Molding• Low Viscosity/Extended Pot Life• Fast Cycle Time• Overmolding Capabilities• Pigmentable• Etc


Processable via Injection Molding

• Silastic® F-LSR processes like conventional dimethyl silicone LSR• Fabrication of intricate fuel resistant parts is now possible• No special equipment or tooling is necessary• Pot life > 3 days is typical

BA

Injection Molding Machine•Standard Injection Molding Machine•Special LSR Screw and Barrel•Spring loaded Non-Return-Valve•Cooled Barrel to 23°C

Mold•Heated Mold up to 125 - 175°C•Cold Runners•Hardened Steel•Exact Finishing 1/1000 mm•Vacuum

Pump / Mixer•Hydraulic or Pneumatic•Pressure 180 - 220 bar•Trough Static Mixer•Plus Color Additive

Silastic LSR•Pourable to Paste•2-Component•1:1 Mixing Ratio•Supply in 20 l pails or 200 l Drums

Injection Molding Equipment

BA BA

Injection Molding Machine•Standard Injection Molding Machine•Special LSR Screw and Barrel•Spring loaded Non-Return-Valve•Cooled Barrel to 23°C

Mold•Heated Mold up to 125 - 175°C•Cold Runners•Hardened Steel•Exact Finishing 1/1000 mm•Vacuum

Pump / Mixer•Hydraulic or Pneumatic•Pressure 180 - 220 bar•Trough Static Mixer•Plus Color Additive

Silastic LSR•Pourable to Paste•2-Component•1:1 Mixing Ratio•Supply in 20 l pails or 200 l Drums

Injection Molding Equipment


Fast Cycle Time

• Short cycle times enhance process productivity and production flexibility• Mold temperatures can be reduced whilst retaining short molding cycles• Temperature dependence for platinum cured F-LSR is much less than

for peroxide cured high consistency FSR

0123456789

10

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0

Time, min

Torq

ue, l

b-in

F-LSR 120°C F-LSR 140°C F-LSR 160°C

FSR 160°C FSR 180°C FSR 200°C


Overmolding Capabilities• Fast cycle times can still be achieved at reduced molding

temperatures it is therefore possible to overmold Silastic® F-LSR onto temperature sensitive plastic parts

• This capability offers scope for supply chain efficiencies since multiple operations can be integrated (either by the silicone or the plastic molder)

• Key benefits include:– Saving time– Saving costs on shipment and stock of intermediate parts– Reducing quality assurance issues of incoming parts made

elsewhere– Removing the cost of assembling parts

• F-LSR can enable efficiency improvements through innovative design possibilities and flexibility in the fabrication of multi-component parts (rubber-plastic composites)


Conclusions from PART 2• This new class of F-LSR materials unites FSR and LSR

technologies with a new range of 100 mol% Liquid Fluorosilicone Rubber (Silastic® F-LSR)

• This product line is further complemented with an expanded range of 40 mol% copolymer offerings

• Materials can be processed with standard liquid injection molding machines to achieve fabrication of intricate parts with a high level of chemical resistance

• New design possibilities are now available with this unique technology

• We are now in the position to offer the market a family of materials that combines the best properties of high consistency FSR with the processing efficiencies of an LSR


Final Summary• We have described 2 areas of recent innovation in the field of

FLUOROSILICONE RUBBER In traditional high consistency form, optimised FSR hose liners

facilitate the continued growth in turbocharging, with its associated benefits (reduced CO2 emissions, improved fuel economy etc) We have demonstrated performance to continuous temperatures

of 200-225C, exceptional oil resistance and a unique, patented solution that achieves high and stable interlayer adhesion

In liquid form, our Silastic® F-LSR materials offer new design possibilities with both copolymer & 100 mole% fluorinated offerings Their combination of chemical/temperature resistance,

processability and fast cycle times make these new materials unique to designers, fabricators and OEMs who are looking for innovative and differentiated solutions

The opportunity now exists to fabricate small, intricate parts that withstand contact with aggressive fuels/oils over a wide range of operating temperatures


Thank you for Listening!

Dave Lawson IRC 2009 Presentation

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