Complex Esters

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Staff member
Jun 5, 2002
Iowegia - USA
Some time ago a member asked us to explain Complex Esters. After reading;f=4;t=000056 this thread you know that esters are pure lubricants made from raw materials such as special alcohols and selected acids. When an alcohol and an acid are brought together with a catalyst, the temperature of the mixture goes up due to this being an exothermic or "giving-off-heat" reaction, and two main products are formed, the ester itself and some water. The mixture is then purged with nitrogen while heated further and by using vacuum stripping, the water is removed from the ester. For machine lubrication, we know there are about 50 useful diesters and six times that many variations of polyolesters. While some diesters have certain advantages, such as low pour points and seal swell, so do polyolesters, such as higher thermal stability and lower coefficient of friction, just to name a few. Now one could mix these esters in various ratios to combine their advantages, but each ester's advantage/disadvantage might show up in the final mix. What if you could get the best of both worlds in one ester? Along comes complex esters. Recall that for a polyolester such as TMP, we take an alcohol such as timethylpropane and react it with a acid, preferably a fatty acid such as heptanoic acid. For a polyolester such a pentaerylthritol ester (PE), we can take pentaerylthritol (alcohol) and react it with monoacid such as a valeric acid. If we also react the monoacid with an oleic acid, we obtain a polyoelate ester. Recall that for a di-ester, we can take for example a 2-ethylhexanol (alcohol) and react it with sebasic acid and get 2-ethylhexyl sebacate, a seal swell additive. Let's take Trimethylpropane (alcohol), 2-ethylhexanoic acid, Isopalmitic acid, heptane (an alcohol), and use Stannous octoate as the catalyst and put them into a flask. After the reaction is complete, the flask is heated to approx. 250 C under vaccum and all water is literally removed from the mixture. Acid content is adjusted via calcium oxide resulting in a tbn of 0.03 to 0.5; a very neutral ester. The resulting liquid, depending on the ratios of virgin components was approx. 3.2 cSt to 15 cSt, had a very light yellow tinge to it, and the resulting yield was 87%. Any solids that remained were filtered through very fine filters. Result: an ester that has very low pour points, high VI's, seal swell properties close to mineral oils, excellent lubricity (low coefficient of friction, high film strength, High Temperature/High Shear), and excellent additive compatibility. By adjusting processing parameters, as with PAO's, we can truly chemically engineer, through molecular modelling and design, just about any ester to perform as specified. So what is the name of the resulting ester? A polyolester [ August 09, 2004, 06:25 PM: Message edited by: MolaKule ]
I see at the Exxon/Mobil site their line of Esterex TM esters consists of 1. Adipate 2. Phthalate 3. Trimellitate 4. Dibasic 5. Neopolyol 6. Complex It is interesting in their marketing that they have a line sheet reference for Potential Applications for Esters that include drive line , hydraulic ect ect but when it comes to Automotive Engine Oil only the adipate , phthlate and neopolyol are grouped for such use to include blending with other basefluids . The complex ester C4261 and C4461 are strangely omitted from recommended use in automotive engine formulas and or as the sole base fluid .
I think what they are defining as neopolyol esters is what I described above. Neo meaning new types of complexed polyolesters. Their complex esters are specialty applications such as for aerospace and military. Their complex esters I would describe as advanced, specialty esters such as polyphenyl ether esters, alkyl-Poly-methacrylates, perfluoropolyesters, PFPE's, cycloaliphatic esters, dialkylcarbonates, silicone esters, etc.
Originally posted by MolaKule: So what is the name of the resulting ester? A polyolester
Isn't that what suits were made of in the 1970s? [Big Grin] Dan
Maybe slightly off topic: Has anyone used Uniqema's friction modifiers in their formulations? In particular Perfad FM 3388? According to their rep, it is an ashless friction modifier with superior oxidation stability and supposedly surpasses the FM properties of Moly in lubes. Any info? Thanx
MolaKule, Thanks for the reply . BTW a member has pointed out to me that the two esters I brought up have a very high VI at both 40 and 100c . Looks like too high to blend down for automotive use . Esterex Obviously the wrong thread to speak about the Alkylated Nathalenes from E/M but I was under the impression that they had many different viscosity's available for blending . Looks like they get the job done using their many Spectrasyn PAO's for the most part while using the two AN's. faa777 , Welcome to the forum [Cheers!] You asked an interesting question there so lets start a topic of it's own . [ August 10, 2004, 06:35 AM: Message edited by: Motorbike ]
Motorbike, That would be a good topic since Alkylated Naphthalenes and benzenes are set to possibly replace expensive esters. More testing will show if they will really do this. What I was trying to say in the previous post was this: Marketing data and Chemistry/Tribology Journals often use the same terms to refer to different things. I attempt to use descriptions from references like the STLE or chemistry journals in lieu of marketing descriptions. faa777, I have seen the specs but have never experimented with it. See the Intersting Articles for new info. [ August 10, 2004, 01:00 PM: Message edited by: MolaKule ]
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