Use of Super Heavy Naphthenics in Lubricant Formulations

1
Use of Super Heavy Naphthenics in Lubricant
Formulations

• Luis Bastardo-Zambrano, PhD
• Nynas Naphthenics AB
• Nynashamn, Sweden

2
Outline

• Introduction Base Oil Market Overview
• Bright Stocks
• Super heavy naphthenic oil (Naphthenic 4000) and
  Polyisobutenes
• Film Strength
• Thickening Effect
• Tackiness
• Shear Stability

3
Base Oil Market Overview

• Base stock supply is estimated at 931000
  barrels/day more than half Group I
• Global demand may increase by 6 by 2010 (34 of
  it in the Asia/Pacific region)
• Shift to higher quality oil worldwide (Group II
  and Group III)
• Detriment of Group I production, especially
  bright stocks
• Bright stocks output fell by 8 between
  1995-2005. Group I shut downs, will bring down
  bright stocks production by 10 in the next 10
  years.

Tocci, L. High stakes for base oils.
LubesnGreases. Vol.13 (1). 2007. DeMarco, N.
Totals Take on Base Oil Balances. Lube Report.
February 2007.
4
Bright Stocks

• High viscosity base oils refined from paraffinic
  crude
• Mainly use is
• Marine oils
• Monograde motor oils
• Gear oils
• Greases
• Other products
• Possible substitutions
• PIB (Polyisobutene)
• PAO (Polyalphaolefins)
• Heavy Naphthenics

5
Super Heavy Naphthenic Oil

• The Super Heavy Naphthenic Oil used in this work
  (Naphthenic 4000) is a product with a very high
  viscosity (4800 cSt at 40C) and excellent
  solvent power (aniline point 80C)
• Naphthenic 4000 can be used as additive in gear
  oils, metalworking fluids, greases and oil
  treatment as well as in blends with lower
  viscosity naphthenic oils to obtain naphthenic
  bright stocks
• It displays interesting properties such as
• Very good shear stability
• High film strength
• High tackiness
• Very low carbon residue (lt0.10)

Naphthenic 4000
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Tests on Naphthenic 4000

• The super-heavy naphthenic oil Naphthenic 4000
  was compared with several commercial PIBs
  presenting different molecular weight
• The following properties were tested
• Film strength
• Thickening effect
• Tackiness
• Shear stability

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Main Properties of the PIBs Tested
Characteristics Method PIB A PIB B PIB C PIB D
Number average molecular weight GPC 1000 1050 1600 2300
Viscosity _at_ 40C (cSt) ASTM D 445 4650 7750 21000 48000
Viscosity _at_ 100C (cSt) ASTM D 445 190 230 725 1500
Density _at_ 20C (g/cm3) DIN 51757 0.890 0.890 0.900 0.900
Pour point (C) ASTM D 97 -9 -3 -4 0
Flash point (C) ASTM D 92 180 210 215 220
8
Film Strength - Method

• Film strength Ability of a lubricant to
  withstand the effects of load
• Method used ASTM D2783 (Four-Ball Test). Upper
  ball under load and rotating (speed 1760 40
  rpm)
• Film strength given by initial seizure
• Materials tested Naphthenic 4000, PIB A and
  PIB D

Naphthenic 4000 Film Strength 2 x PIB A Film
Strength Naphthenic 4000 Film Strength 50 higher
than PIB Bs
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Thickening Effect - Method

• Increasing amounts of Naphthenic 4000 and the PIB
  having the same viscosity (PIB A) were added to
  the naphthenic oil Base oil 400
• Treating rates of 10, 20, 30, 40, 50, 60, 70, 80
  and 90 were used
• After each addition, the viscosity of the blend
  was measured by ASTM D 445
• A viscosity curve was obtained for each thickener

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Thickening Effect Results and Discussion (1)
Naphthenic 4000
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Thickening Effect Results and Discussion (2)

• The PIB A has a more marked thickening effect
  compared to the Naphthenic 4000
• The difference in viscosity becomes evident at
  additions above 30 treating rates
• The difference is most pronounced at high
  treating rates (gt 60)

12
Tackiness - Method

• Tackiness is defined as the resistance to flow
  in extension and is a combination of cohesivity
  and adhesivity
• The tackiness was measured in a filament break-up
  rheometer
• The test fluid is placed between two cylindrical
  test fixtures (rheometer plates) and is submitted
  to an axial step-strain applied generating the
  formation of an elongated liquid thread

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The Capillary Break-Up Extensional Rheometer
Filament Formation
Axial strain
Axial strain
14
Tackiness Tests Experimental Conditions

• Naphthenic 4000 and four PIBs were added to the
  naphthenic oils Base oil 400 and Base oil 110
• Treating rates of 0.5 and 1.5 were used
• The time evolution of the filament diameter for
  the pure and additivated oils was followed
• The final gap between the rheometer plates was
  set to 8 mm for the tests performed on Base oil
  400 and to 6 mm for the tests carried out on Base
  oil 110
• The final gap between the plates must be kept
  constant through a series of experiments as it is
  directly correlated to the deformation to which
  the material is submitted during the test

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Tackiness Tests on Base Oil 110 with 1.5
Treating Rate
16
Tackiness Tests Results and Discussion

• Naphthenic 4000 gave a tackiness increase equal
  to that given by the PIB B (having a viscosity at
  40C of 7750 cSt)
• Increasing the treating rate has a positive
  effect both for Naphthenic 4000 and the PIB B.
  The effect is more marked with Base oil 110.
• As expected, the tackifying effect of the PIBs
  increases with increasing molecular weight.
• Nevertheless, the higher the molecular weight of
  the PIBs, the higher the sensitivity to shearing
  forces.

17
Shear Stability Tests - Method

• Method used CEC L 45-A-99 (Viscosity shear
  stability of transmission lubricants Tapered
  roller bearing rig)
• The bearing is loaded axially with 5000 N,
  rotated at 1475 rev/min and maintained at a
  temperature of 60C.
• The viscosity of the fluid before and after the
  test was measured using the method DIN 51562. The
  result of viscosity lost by the fluid

The polymer molecules break when submitted to
high shear stresses
18
Conclusions

• Worldwide production of base oils is shifting to
  higher quality products, Group II and III base
  oils
• These changes may cause shortage of Bright Stocks
  in the market
• Heavy naphthenic oils and PIBs are alternatives
  available right now
• The super heavy naphthenic oil Naphthenic 4000
  outperforms PIBs in properties such as film
  strength and shear stability
• Conversely, the thickening effect of PIBs is
  higher than that of the Naphthenic 4000
• The impact on tackiness of Naphthenic 4000 is
  comparable to that of the medium molecular weight
  PIBs, while high molecular weight PIBs show a
  more marked tackifying effect