Chemical Components of a DI Additive package III

[MolaKule]

This question is open to all BITOG members.

Special Esters (Group V base oils) are being developed and tested for Electric Vehicles.

These esters will cool the electric motors, cool control electronics, provide gearbox protection for both bearings and gear teeth, and cool the batteries.

Considering the material make-up of the above EV components, what additive chemistry might be used from this list

https://bobistheoilguy.com/forums/threads/additives-xii-multifunctional-additives.41173/

Post #10

to enhance the performance of these esters and protect the above components?

 

[Tom NJ]

I've read that esters are being looked at for EVs but have not yet seen what ester chemistry is of interest. Do you happen to know the ester chemistry? As a start I would be looking at low viscosity esters for cooling efficiency as well as low polarity and ashless additives.

Re the additives, esters respond very well to amine anti-oxidants as opposed to phenolics. Which amines and what dosage will depend on the temperature profile the oil is exposed to. Phosphates also work well in esters for anti-wear and EP, although I doubt they will go the TCP route due to toxicity concerns in aircraft cabin air. Perhaps TPPT for better EP and hydrolytic stability. Triazoles work well for yellow metal protection, and there are proprietary additives for rust protection in esters used in aviation oils. Silicones may be used for foam, and a friction modifier and demulsifier additive may be useful depending on the polarity of the ester selected.

Shouldn't need any detergents, dispersants, pour point depressants, VI improvers, or seal swell agents.

Of course a complete temperature, load, materials, and operating environment profile is needed to do a proper job of formulating, so the above are just preliminary ideas.

 

[BusyLittleShop]

I'd look into free flowing Turbine or Jet Oils since they are made from a specially
prepared, ester base stock...

 

[Tom NJ]

I agree a low viscosity may be best depending on the load and engine design, but the POEs used in jet turbine oils are not ideal for this application. The esters used in jet oils are constructed with high percentages of short chain fatty acids, mainly C5 at 40-55%, in order to meet the low temperature flow and tight viscometric specifications for jet oils. C5 acid stinks and could be corrosive if hydrolyzed, and also yields an ester with a lower VI, lower lubricity, and higher volatility. I tend to avoid using C5 acid for indoor use due to potential odor.

I would prefer to trade some of that low temperature performance in jet POEs for higher VI & lubricity and lower volatility by using longer acids with smaller polyol alcohols. I would also add some branched acids to improve coking tendencies and hydrolytic stability. That's the beauty of POEs - custom designed molecules optimized for the application.

Also jet engine oils contain TCP (tricresyl phosphate) anti-wear additive which has toxicity concerns. There are better choices for automotive engines.

 

[Gentleman farmer]

Triphenyl phosphorothioate & diisodecyl adipate.

 

[Tom NJ]

Triphenyl phosphorothioate & diisodecyl adipate.

So long as the temperatures are not too high that's not a bad combination. DIDA may be a bit thin at 3.6 cSt @ 100°C and it would need some additional additives, like anti-oxidants and corrosion inhibitors. TPPT is what I had in mind for anti-wear/EP. A POE base may provide a lifetime oil, again depending on the operating environment.

 

[MolaKule]

Triphenyl phosphorothioate & diisodecyl adipate.

True, the ester(s) needed would have to be low viscosity esters in the range of potentially say 2.5 to 4.5 cSt to reduce energy (pumping) losses and to promote efficient cooling. We are assuming a closed loop cooling system similar to an AT system that touches electric motors, control electronics, provide gearbox protection for both bearings and gear teeth, and cool the batteries.

The primary question was: "Considering the material make-up of the above EV components, what additive chemistry might be used from this list."

The materials in an EV system are mostly copper and aluminum components with steel components as well. Conventional additives that contain phosphorus and sulfur compounds have to be ruled out.

So the first considerations would have to be Metal Inhibitors/Metal deactivators, anti-oxidants, and rust inhibitors.

Metal Inhibitors/Metal deactivators such as the N, N-bis(2-ethylhexyl)-methyl-1H-benzotriazole1-methanams or the 2,5 dimercapto-1,3,4-thiadiazole derivatives could serve this function.

For Anti-wear, Multi-functional compounds such as the 2,5 dimercapto-1,3,4-thiadiazole derivatives or similar could be also be used as Metal Inhibitors/Metal deactivator/anti-oxidant agents as well as function in the anti-wear role. Borates or potassium borate compounds could be used as primary or co-anti-wear and anti-friction agents.

Rust inhibitors such as compounds of the fatty acid derivatives of 4,5-dihydro-1H-imidazol could serve as an agent for this role.

Ester research into ester structure is still ongoing to determine which ester type will provide the best electrical isolation, breakdown voltage, and thermal heat transfer coefficients. An electric drive motor or Inverter is more efficient when it windings and components, respectively, are cooler. The copper windings have resistance such that the higher the temperature, the greater the resistance and hence, the greater the internal energy losses. These internal or I^2R losses raise internal temperatures of the components.

Studies have shown that many lower viscosity synthetic fluids, and especially ester fluids, exhibit greater thermal conductivities than other fluids. The greater the thermal conductivity of the fluid, the greater the heat transfer and the cooler the components.

 

[Pablo]

True, the ester(s) needed would have to be low viscosity esters in the range of potentially say 2.5 to 4.5 cSt to reduce energy (pumping) losses and to promote efficient cooling. We are assuming a closed loop cooling system similar to an AT system that touches electric motors, control electronics, provide gearbox protection for both bearings and gear teeth, and cool the batteries.

The primary question was: "Considering the material make-up of the above EV components, what additive chemistry might be used from this list."

The materials in an EV system are mostly copper and aluminum components with steel components as well. Conventional additives that contain phosphorus and sulfur compounds have to be ruled out.

So the first considerations would have to be Metal Inhibitors/Metal deactivators, anti-oxidants, and rust inhibitors.

Metal Inhibitors/Metal deactivators such as the N, N-bis(2-ethylhexyl)-methyl-1H-benzotriazole1-methanams or the 2,5 dimercapto-1,3,4-thiadiazole derivatives could serve this function.

For Anti-wear, Multi-functional compounds such as the 2,5 dimercapto-1,3,4-thiadiazole derivatives or similar could be also be used as Metal Inhibitors/Metal deactivator/anti-oxidant agents as well as function in the anti-wear role. Borates or potassium borate compounds could be used as primary or co-anti-wear and anti-friction agents.

Rust inhibitors such as compounds of the fatty acid derivatives of 4,5-dihydro-1H-imidazol could serve as an agent for this role.

Ester research into ester structure is still ongoing to determine which ester type will provide the best electrical isolation, breakdown voltage, and thermal heat transfer coefficients. An electric drive motor or Inverter is more efficient when it windings and components, respectively, are cooler. The copper windings have resistance such that the higher the temperature, the greater the resistance and hence, the greater the internal energy losses. These internal or I^2R losses raise internal temperatures of the components.

Studies have shown that many lower viscosity synthetic fluids, and especially ester fluids, exhibit greater thermal conductivities than other fluids. The greater the thermal conductivity of the fluid, the greater the heat transfer and the cooler the components.

Several listed compounds contain sulfur. Are they not harmful to the metals??

 

[Gentleman farmer]

What about phosphonium based ionic liquid? Not included in this list though.

 

[MolaKule]

Several listed compounds contain sulfur. Are they not harmful to the metals??

The 2,5 dimercapto-1,3,4-thiadiazole has strong linkages which has a low probability of free sulfur disassociation at elevated temps. The oxidative and temperature stability of any molecule is an important consideration here.

Recall I said 'derivatives,' in which I meant 'types' of similar molecules that could be modified for improved performance.

N, N-bis(2-ethylhexyl)-methyl-1H-benzotriazole1-methanam and 4,5-dihydro-1H-imidazol have only CHN atoms in its molecule.

What other compounds did I mention that might be questionable?

​

 

[MolaKule]

What about phosphonium based ionic liquid? Not included in this list though.

For which agent or function?

The short list was an example of commercially available compounds (or their derivatives) that could be used in an EV fluid and currently being tested for component compatibilities.

I know that synthesized Phosphonium-based ionic fluids have better thermal stability than do some ammonia-based (high N) liquids.

Phosphonium-based ionic and other ionic compounds could be used if their electrical isolation, breakdown voltage, and thermal heat transfer coefficients were further characterized.

 

[Pablo]

The 2,5 dimercapto-1,3,4-thiadiazole has strong linkages which has a low probability of free sulfur disassociation at elevated temps. The oxidative and temperature stability of any molecule is an important consideration here.

Recall I said 'derivatives,' in which I meant 'types' of similar molecules that could be modified for improved performance.

N, N-bis(2-ethylhexyl)-methyl-1H-benzotriazole1-methanam and 4,5-dihydro-1H-imidazol have only CHN atoms in its molecule.

What other compounds did I mention that might be questionable?

​

Maybe it was just the 2,5 dimercapto-1,3,4-thiadiazole.

Thanks, makes sense. I mean the highest temps cannot be so harsh here.

 

[Tom NJ]

The 2,5 dimercapto-1,3,4-thiadiazole has strong linkages which has a low probability of free sulfur disassociation at elevated temps. The oxidative and temperature stability of any molecule is an important consideration here.

Likewise for TPPT. I used it in a high temperature oven chain oil and ran the formulation through multiple oxidation & corrosion stability tests run 72 hours @ 425°F. All passed with flying colors, and I smelled the used oil for any sulfur odor - there was none. The formulation went commercial in bulk with no odor complaints, so the sulfur appears to be quite stable.

 

[MolaKule]

Likewise for TPPT. I used it in a high temperature oven chain oil and ran the formulation through multiple oxidation & corrosion stability tests run 72 hours @ 425°F. All passed with flying colors, and I smelled the used oil for any sulfur odor - there was none. The formulation went commercial in bulk with no odor complaints, so the sulfur appears to be quite stable.

Thanks Tom, that's good to know.

Added: Another potential candidate for EV fluid additives.

 

[Foreman04]

Thanks Tom, that's good to know.

Added: Another potential candidate for EV fluid additives.

Likewise for TPPT. I used it in a high temperature oven chain oil and ran the formulation through multiple oxidation & corrosion stability tests run 72 hours @ 425°F. All passed with flying colors, and I smelled the used oil for any sulfur odor - there was none. The formulation went commercial in bulk with no odor complaints, so the sulfur appears to be quite stable.

No, you don’t want to be using TPPT in a new formulation now. It has a new Global reclassification attached to it so people are now moving away from it. You’ll want to look at alternatives to TPPT in a formulation because if you don’t do it now, you end up doing it later. It’s recent reclassification.
Aquatic Chronic 1
H410 Very toxic to aquatic life with long lasting effects.

 

[Tom NJ]

Thanks, I had not heard that. But then I have been retired for 17 years so I am out of touch with toxicity classifications, and no longer formulating lubricants (except in my head).

 

[MolaKule]

No, you don’t want to be using TPPT in a new formulation now. It has a new Global reclassification attached to it so people are now moving away from it. You’ll want to look at alternatives to TPPT in a formulation because if you don’t do it now, you end up doing it later. It’s recent reclassification.
Aquatic Chronic 1
H410 Very toxic to aquatic life with long lasting effects.

Ok, so it has been reclassified recently for Aquatic Toxicity. Good to know.