A new insight into the benefits ofsynthetic esters in lubrication

Nicolas FRIZON

Lubgrax Annual meeting – August, 2017

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AGENDA

I. General properties of synthetic esters▪ The relationship between chemical structure and properties▪ The useful features of esters in lubrication

II. Traditional use of esters▪ Various demanding or severe lubricating applications :from jet engines to oven chains

III. Requirements on future lubricants :how esters will contribute

▪ High performance and lowered environmental impact :esters take up the challenge

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GENERAL PROPERTIES OF SYNTHETIC ESTERS

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Volatility, Rheology

δ-

δ+

δ-

Property Unit Naphthenic Gr I Gr III PAOAlkyl

NaphthaleneDiester

Neopolyolester

Complex ester

Viscosity at 100°C mm²/s 4.6 5.0 5.1 5.1 4.8 5.3 4.9 5.7

Viscosity at 40°C mm²/s 31.3 29.8 26 24.1 28.7 26.6 22.6 28

Flash point COC °C 194 195 226 245 232 234 267 265

Evaporation250°C – 1 h*

% 43.4 38.3 19.3 5.6 12.0 4.7 2.3 2.6

Viscosity Index - 25 92 122 145 81 136 148 160

Pour Point °C -51 -10 -18 -46 -48 -54 -38 -38

� Esters show lower volatility and higher flash points than hydrocarbons of equivalent viscosity, thanks to stronger intermolecular attraction

� Esters show high Viscosity Indices and low Pour Points as they generally exhibit linear, asymmetric structures

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Tribology

Property Unit Gr I Gr IIIAlkyl

Naphthalene PAO DiesterNeopolyol

ester

Viscosity at 100°C mm²/s 4.18 4.25 4.82 3.95 3.56 4.40

Viscosity at 40°C mm²/s 21.3 19.7 28.7 17.3 13.7 19.7

4 ball Wear Scar40 kg, 1 h

(ASTM D4172)

mm1.10 0.76 0.91 0.73 0.85 0.64

60 kg, 30 min mm - - - 1.78 - 0.71

Property Unit PAO Gr IIIAlkyl

Naphthalene DiesterNeopolyol

esterComplex

ester

Viscosity at 100°C mm²/s 3.95 4.25 4.82 3.22 4.40 5.73

Viscosity at 40°C mm²/s 17.3 19.7 28.7 11.6 19.7 28.0

HFRR -5N, 60°C , 75 mnFriction coefficient

--0.492 0.311 0.296 0.225 0.230 0.220

� Esters show high affinity with positively charged metal surfaces, generating friction modification

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Polarity

Anilin Points

100°CGroup I, II, III, PAO

130°C

90°C Naphthenics

32°C Alkyl Naphthalenes

10°C Esters

-30°C PAG

Micro-Coking TestGFC-Lu-27-A-13

230-280°CPAO 40

PAG40 mm2/s

Neopolyol ester

40 mm2/s

�Oil quantity: 0.6 cm³

�Plate inclination: 1° to the

hot point

�Cold point temperature:

variable (200°C to 280°C)

�Hot point temperature:

variable (250°C to 330°C)

�Duration: 90 minutes

� Esters are good polar solvents and help dissolve components into non polar base stocks

� Esters show detergency and dispersivityproperties

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Thermo-oxidative stability

Chemical function β-elimination Neopentyl structure Branched acid

ASTM D4636

204°C – 72 h Gr I Gr III PAOAlkyl

NaphthaleneDiester

Neopolyol

ester 1

Neopolyol

ester 2

Test tube

Deposits

5 mm2/s @100°C fully formulated fluids

� Ester function is highly resistant to oxidation, and increases oxidation stability of adjacent carbon atoms

� Neopentyl structure inhibits β-elimination and greatly improves thermal stability

� Branched, short hydrocarbon chains further improve resistance to oxidation

Coking propensity

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� Esters show low coking and deposit formation properties

� Use of branched hydrocarbon chains favours clean decomposition pathwaysonce oxidation is initiated

Micro-coking Test

230-280°C

40 mm²/s

Unit PAO PAG Complex

ester 1

Complex

ester 2

Linear

Neopolyol

ester

Branched

Neopolyol

ester

Deposit temperature °C <230 <230 <230 <230 273 >280

Average Merit - 6.6 5.5 7.9 6.9 8.8 10

Metal plates -

Environmental profile and Food contact

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Base fluid Mineral PAO PAG Esters

Typical biodegradability

OECD 301BMax. 40% Max. 60% 10 - 70% 10 - 95%

Renewable carbon content

0% 0% 0 – 20% 0 - 100%

� Ester function may be degraded by bacteria, making these compounds biodegradable

� Esters can be made of acids coming from vegetable sources : they may contain high amounts of renewable carbon

� Certain esters are HX1 approved for the food industry

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TRADITIONAL USE OF ESTERS

Jet engines, compressors

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Aircraft gas turbines require lubricants showing:

� superior thermal and oxidative stability (up to 220°C in bulk)� low liquid and vapour phase coking (hot parts in

the engine – up to 375°C)

In volumetric air compressors, lubrication may take place in the compression chamber:

� Need for high resistance to oxidation (up to 230°C)� Need for excellent deposit control (safety issue : valve

sticking, auto-ignition)

Refrigeration compressors using HFC require lubricants showing:

� the right miscibility/immiscibility profile with HFC� very low pour points� good lubricity

2-stroke engines

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Clean burning properties of esters, detergency, natural lubricity, good biodegradability are precious features for 2-stroke engines

Compared to mineral oils, ester based 2-stroke engine oils :

� reduce exhaust smoke� reduce wear in engines� reduce deposit and varnish formation� show a much better environmental profile

Oven chains

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High temperature chain oils face :

� High evaporation rates� Thermal decomposition� Oxidation and formation of gummy or carbonaceous residues� Safety issues through ignition and fires

Synthetic esters have been providing :

� very low volatility, consequently high flash and fire points� high resistance to thermo-oxidation� Low deposit formation features

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REQUIREMENTS ON FUTURE LUBRICANTS: HOW ESTERS WILL CONTRIBUTE

Tougher requirements in modern lubrication

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Market drivers will favour synthetic performance products

Evolution on lubrication requirements is driven by :

� Commercial competition : the race for better performance, more durability,reduced costs

� OEM requirements, standards and legislation : require more energy efficiency,induce higher power density, provide better safety

� Sustainability : increasing demand for low environmental impact,renewable lubricants

Modern PCMO

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Future engine oils will need lower volatility, higher thermo-oxidative stability and improved cleanliness

ILSAC GF-5

Additives - 14,72

Group III 4 mm2/s 9,85

PAO 4 mm2/s 20,00

Group III 6 mm2/s 55,43

ILSAC GF-5 test

Additives - 14,72

Group III 4 mm2/s 9,85

Neopolyol ester 4 mm2/s 20,00

Group III 6 mm2/s 55,43

ACEA C1-2012

Additives - 26,20

Group III 4 mm2/s 53,80

PAO 4 mm2/s 20,00

ACEA C1-2012 test

Additives - 26,20

Group III 4 mm2/s 53,80

Neopolyol ester 4 mm2/s 20,00

Tests on 5W-30 engine oils, ACEA C1-2012 and ILSAC GF-5 performance level

Volatility, cleanliness

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Oil 1 PAO4 ILSAC GF-5

Oil 1 Neopolyol ester ILSAC GF-5

Oil 2 PAO4 ACEA C1-2012

Oil 2 Neopolyol ester ACEA C1-2012

TEOST 33C GF-5 GF-5 + ester

Rod Deposit mg 18.4 13.1

Filter Deposit mg 5.0 3.2

Total Deposit mg 23.4 16.3

NOACK volatility (correlation by TGA – ASTM D6375)

Oil 1 PAO4 ILSAC GF-5 9.3 %

Oil 1 Neopolyol ester ILSAC GF-5 7.7 %

Oil 2 PAO4 ACEA C1-2012 12.4 %

Oil 2 Neopolyol ester ACEA C1-2012 11.1 %

TGA – 200°C – O2

Esters may be used to reduce volatility and deposit formation in

engine oils

Volatility, cleanliness

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Evaporation

Pyrolysis

ResidueTGA

250°C - O2

280 mm2/s, trimellitate/neopolyol ester based

250 mm2/s, 100% branched neopolyol ester based

400 mm2/s, 100% branched neopolyol ester based, AO 1

400 mm2/s, 100% branched neopolyol ester based, AO 2

Micro-Coking Test 250 mm2/s - trimellitate/iso-paraffin 250 mm2/s – branched neopolyol ester

230-280°CDeposit TemperatureAverage Merit

°C--

2539.3

> 28010.0

250-300°CDeposit TemperatureAverage Merit

°C--

2507.9

2598.6

280-330°C

Deposit TemperatureAverage Merit

°C--

< 280

2.3

< 280

6.7

The ideal profile of branched neopolyol esters :

� Slow evaporation� Quick decomposition� Little residue left

Performance and low environmental impact

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Synthetic esters provide:

� High resistance to oxidation

� Natural lubricity

� High VI, improved shear stability

� High flash and fire points

� High biodegradability

� High renewable carbon content

� Biodegradability : >60% (OECD 301B)� Renewable carbon content : >50%

Future hydraulic fluids will need higher performance and will also have to account for improved environmental profile, as requested by latest standards (European Ecolabel, Vessel General Permit, US Biopreferred…)

Properties Test

Method ISO VG 46 – ISO 15380

European Ecolabel compliant

Composition - Saturated ester : 98.746% Additives : 1.254%

Complex ester : 99.095% Additives : 0.905%

Kinematic Viscosity, mm2/s

100°C

40°C

ISO 3104

7.9

45.6

8.31 45.0

Viscosity Index ISO 2909

144 162

Flash Point, °C ISO

2592 281 260

Foam properties, ml Sequence I, II, III

ISO 6247

0-0, 0-0, 0-0 0-0, 10-0, 10-0

Air release (50°C), min ISO 9120

1.9 9.1

Water separability (54°C), min ISO 6614

10 25

Dry TOST, hours ISO

4263-3 >7000 >2100

RPVOT, min ASTM D2272

833 -

FZG Load Carrying (A/8.3/90) Fail Load Stage

ISO 14635-1

10 >12

Van Pump wear (V104C) Cam ring, mg

Vanes, mg

ISO 20763

2.0

12.3

4.1

1.1

New trends, growing interest

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Power densityEnergy

efficiency Durability

SYNTHETIC ESTERSEnvironmental

impact Sustainability Safety

Demand for higherperformance will exploit unexpected benefits of

esters

THANK YOUNYCO Nicolas FRIZON : nicolas.frizon@nyco.frIMCD Brasil Joao PONCHIO : Joao.Ponchio@imcdbrasil.com.br