Episode Transcript
[00:00:00] Speaker A: Good day, everyone. Welcome to lubrication experts. And today I have returning for a third time. This is the first time that anyone has ever returned for a third episode. I have the Andy Weynick. Now, Andy has had already two very, very popular episodes on calcium sulfonate as well as lithium complex. I've actually had people come up to me at industry events and be and actually say, wow, you know, Andy, you got Andy. He's the guy that's like, on every patent that I've ever read. So people are always very excited when Andy comes on. So today, this is actually going to be a bit of a follow up, part two, if you like, to our last episode, which was on lithium based greases. So in the last episode, we were kind of where we got to was a discussion of lubricating properties of lithium greases. And there's a bit of history as to why is it that lithium has become the dominant soap within the industry, and basically it's jack of all trades, master of none, and it does everything pretty well, but it has no particular downside. And that's why they are so popular. And I think by volume. The last NLGI survey said that they were in the ballpark of 70% of global grease volume. Now, today, we're going to take that discussion a little bit further, because we would like to understand exactly how lithium greases are manufactured, as well as some of the new developments.
Yes, it is an old technology, but technology is always moving forward, and Andy's certainly a part of that. So we're going to talk a little bit about some of the new manufacturing methods that are coming to lithium greases, how that might affect the performance and things like that. So, without further ado, Andy, welcome back on the podcast.
[00:01:44] Speaker B: Thanks, Ray. It's always great be able to talk with you halfway around the world.
And I've been looking forward to this, and there were some delays along the way, but we finally done it. So here we are.
And I think probably now, because of the time, about six months, we didn't want it to be that long, but that's how it's turned out to be. I want to do a very brief review of the really top mountaintop items we discussed. Discussed. So that the viewers today won't be kind of wondering where I'm coming out from in terms of, you know, being left field.
[00:02:20] Speaker A: Yeah, that sounds great.
[00:02:22] Speaker B: Lithium soap greases, of course, were first published in the open literature with those five classic Clarence Ural patents in 1942.
And from that point on, the spread of lithium soap greases in terms of their use and in terms of technology development was very rapid, very rapid.
All simple lithium soap greases are really made by a very similar process. You put in the twelve hydroxy stearic acid in a portion of the base oil and then you heat it up to an appropriate temperature of around, oh, 82, 88 degrees celsius, well below the boiling point of water. And then you add the lithium hydroxide, usually in the form of an aqueous solution, and then you react it and you form your simple lithium sulfuries.
Clarissa Earl's patents were lithium stearate. A few years later and we'll talk about this. Toward the end came lithium twelve hydroxy stearate.
You form the thickener, then you heat the grease up to about 204 degrees celsius. That gets rid of the waters of reaction. It also melts the simple lithium salt thickener and then you cool the grease down. And when you cool it down, you reform the grease structure. And we found, and I'll talk about this a little later, the cooling rate really matters, typically between 204 to about 182 degrees celsius. We found that the cooling rate actually matters quite a bit.
This was discovered within the first ten years of lithium soap greases being documented. And the tool that helped to discover that was electron microscopy in a landmark paper published in the NLGI spokesman in 1947. That's just five years after clearance, the Ural patents.
There was actually a gentleman by the name of Bb Farrington and a co author published for the first time electron micrographs of thickener fiber structures in various greases of various thickener types, including simple lithium soap greases. And we saw for the first time the now well known twisted fiber structure of simple lithium soap greases. And using electron microscopy, we were able to show that critical cooling rate between 204 and about 182 celsius determines how those thickener fibers grow. If you cool it slowly, you get long thickener fibers. If you cool it quickly, if you quench it, you get short thickener fibers. And each of those brings to the table a different set of some grease rheology properties, which I'm not going to go into today. But anyway, this was part of the process. Now that we've set the stage, one more little bit of review. Simple lithium soap greases. Of course you have a simple lithium salt of a long chain monocarboxylic acid, usually stearic, or more preferably today, twelve hydroxy steric acid. That's your simple lithium soap thickener. For lithium complex greases, you have that, but you also have the dilithium salt of a shorter chain dicarboxylic acid, such as sebastic acid, which is a c ten straight chain dicarboxylic acid, or azelaic acid, which is a c nine straight chain dicarboxylic acid.
And those are the differentiations between simple lithium salt creases. Lithium complex greases. Now, I also pointed out that lithium complex greases, they're not true complexes. There is no such thing as a true lithium complex in the strictest chemical sense of the word. Lithium complex greases are co crystallized. Those shorter chain dilithium salts have melting points above 400 degrees celsius. And if you intimately co crystallize the dilithium salts of the shorter chain dicarboxylic acid, and this monolithium salt of the longer chain monocarboxylic acid, stearic, or twelve hydroxy stearic acid, then the high melting point of the short chain dilithium salt will translate to the overall structure, and you'll get that huge increase in dropping points. So lithium complex greases are co crystallized. That's how they get their high dropping points.
With that stage set, we can now talk about lithium complex greases, their development and the technology of how they are made, because they're intimately related, and you can't really separate the two.
So I've had people ask me, when was the first lithium complex grease developed? Well, that depends on how you define lithium complex grease. As I pointed out in the previous podcast, some early complex silk thickened greases were developed in such a way where they didn't really meet today's definition of a true complex silk thickened grease. And the dropping points weren't even improved. That's the case with the very first so called lithium complex greases. There was one patent that issued by a man named McClellan McLennan in 1947, five years after the clarity Ural patents. And he had a number of examples, eleven of them, three of which were what he called lithium complex greases. But they were nothing like what we consider a lithium complex grease today. And in fact, he didn't improve the dropping points. And in fact, of those three so called lithium complex grease examples, the dropping points were actually lower than what we would consider to be a good, simple lithium soap grease today.
So, probably a better way to ask the question would be, when was the first high dropping point lithium complex grease that uses the kind of chemistry that today we've come to be associated with true lithium complex greases? When were those lithium complex greases first developed and the answer to that question is specifically August 4 of 1959.
A man named Pattenden and coworkers developed in this patent the first documented case of a high dropping point lithium complex grease that uses long chain lithium salt of a long chain monocarboxylic acid and the dilithium salt of a shorter chain dicarboxylic acid. Now, coincidentally, this patent issued only a few months after those five Clarence ERL patents had expired. Don't know if that was by design or not, but that's the way the timing turned out. Now, what patentin did was he didn't use the shorter chain dicarboxylic acid. Instead, he used the diester of the shorter chain dicarboxylic acid, specifically the diesters of sebastic acid or adipic acid. Adipic acid is a c six dicarboxylic acid, and the longer chain fatty acid monocarboxylic acid he used was stearic acid, not twelve hydroxysteric acid. And what he did was he took the stearic acid and the shorter chain diester of the shorter chain dicarboxylic acid, he put them in base oil, and then he reacted it with aqueous lithium hydroxide. Now, the stearic acid to sebastic acid, weight weight ratio for these greases, if you calculate how much sebastic acid actually was released, was about 2.1. Now, this ratio of the longer chain monocarboxylic acid to shorter chain dicarboxylic acid is what I refer to as the thickener acid ratio. And I'm going to be talking about this over and over again by the end of our podcast, our audience will understand why I'm talking about this and what its significance is.
So anyway, that's how he developed his greases, and he got dropping points in excess of 260 degrees celsius in these first lithium complex high dropping point greases, which are excellent.
But that's not the most important thing in the patent. The most important thing in the patent, although I don't think he probably understood the significance at that point, was an observation he made. And that observation was if he didn't use the diasters of the shoulder chain dicarboxylic acid, sebastic or adipic, but instead used the actual acids, he got a grainy product with low thickener yield, and the dropping points weren't even as good as a simple lithium soap grease.
Now that was very important because it gave a hint as to what's really going on here. You see, when you form that thickener and you add the water and the lithium hydroxide. The lithium hydroxide is reacting with the stearic acid, the long chain mono carboxylic acid. And the water is cleaving the esters to release the sebastic acid or the adipic acid, which then promptly reacts with lithium hydroxide to form the dilithium salt. But that reaction is happening in the presence of a lot of yet unreacted esters. And the esters that are reacting are releasing the alcohol moieties on the ends where you had the ester linkages, the esters and the alcohols are very polar materials, and they were acting as what today we would call coupling agents. They were basically helping to couple the lithium salt of the stearic acid and the dilithium salt of the sebastic acid or adipic acid, into that intimate co crystallized structure.
And so when he heated it up to a top temperature of around 204 degrees and then cooled it back down, by that time, most of those alcohols were gone, presumably, and you had this nice cochry slice structure, which gave you the dropping point. And that's really the reason why this worked.
Now, again, as I pointed out, these complexes are not true Werner coordination complexes, which you learn about inorganic chemistry. It was a marketing term, but of course, the marketing term is stuck. And we always call them lithium complex greases. Now, only about a year later, the same group of scientists, inventors, patent and associates, had another patent. And in that one, he did things a little bit differently. He took the stearic acid and he took the shorter chain dicarboxylic acid, and he took a polyhydric alcohol, that's basically an alcohol with specifically two alcohol groups on either end. And he reacted that together separately at the beginning to form a polyester material. Now, I won't go into the chemistry, but because you have two alcohol groups and you have two carboxyl acid groups on the ends of two of your reactants, they can tend to react and form espers, and they just keep propagating the chain until it's terminated by the stearic acid on the end. It was done in a way where you had excess acidity at the end. So it was referred to as an acidic polyester material. He then put that acidic polyester material in initial portion of the base oil, and then he reacted it with an aqueous solution of lithium hydroxide that cleaved all the ester linkages and reacted all of the acid materials, the stearic acid. And he released shorter chain dicarboxylic acid, which was usually in this patent sebastic acid. And then again, he would then heat this thing all the way up to top temperature and cool it back down. And he got really great dropping points again.
Now, the steric to sebastic or stearic to azelaic acid ratio, because he also used azelaic, the thickener acid ratio for that was about 1.5.
But notice it required two heating and cooling cycles to do this. The first heating and cooling cycle was when you form that polyester material, you had to heat it up to reactant, then you cool it back down, and then you put it in the base oil, added the aqueous lithium hydroxide, and then you had to heat that up to form the grease and cool it back down. And once again, all those ester and transient alcohol materials that were present and were formed during the process were acting as coupling agents to co crystallize and intimately associate the lithium stearate and the dilithium azylate or dilithium sebicate to form that necessary intimate co crystallized structure so that you get the high dropping points.
That's how that worked. Well, our next example came about ten years later.
A man named Jelani and some associates had a patent where they claimed that glycols that are left in the grease and that would have applied to some of the earlier patents. Patented work was deleterious to oxidation and water resistance. Now, they didn't provide any data to back that claim up with, but it is consistent with some other things that were reported in the literature much earlier. And of course, this was done because he needed to differentiate what he was going to do with the well established patentin patents. So what he did was he actually used not the esters, but the actual acids. He used twelve hydroxycharic acid, and he used primarily azelaic acid as the shorter chain dicarboxylic acid. He dissolved it in the base oil at about 82 to 93 degrees celsius. He then added the lithium hydroxide as a solution, an aqueous solution of lithium hydroxide, and he reacted. And then he heated that up to 204 to 221 degrees celsius to complete the reaction and remove all the waters of hydration. Now he's using the acid forms so there's no alcohols being given off. Then he cooled it rapidly to 104 degrees celsius, and then he heated it again all the way up to about 190 degrees celsius. And then he rapidly cooled it again to 116 degrees celsius and finished it. Now the thickener acid ratio for his work, that is, the ratio of twelve hydroxysteric acid to azelaic acid, ranged from about 1.6 to 2.95. And he was able to get dropping points as high as 282 degrees celsius. He didn't use alcohols or esters in his grease, so he avoided that. So there weren't any glycols or residual alcohols left in the grease, but he did require those two heating and cooling cycles. Now, when you're making a grease, this is time consuming. In open kettle production, this takes time. So that was a problem, but nonetheless, he avoided the use of esters and the release of alcohols. Now, again, about two years later, the same group, Jelani and associates, developed a slightly different take on this. In this case, he added lithium hydroxide to a solution of only the twelve hydroxy stearic acid, and he used only enough lithium hydroxide to react with that. And then he heated that all the way up to around 150 degrees celsius to complete that reaction and dehydrate it. So at that point you got a simple lithium salt grease. He then cooled it down to lower than 96 degrees celsius. Then he added the shorter chain dicarboxylic acid, specifically azelaic acid, and then he added more lithium hydroxide in aqueous solution form, reacted with that, and then he heated the whole mixture again all the way up to almost 200 degrees celsius to complete the reaction and dehydrated. Then he cooled it back down and he got his grease. He had great dropping points, 329 degrees celsius, his typical dropping point. So that's really good.
And the thickener acid ratio ranged from 2.0 to 3.2.
And he avoided esters and alcohols, but again, two heating and cooling cycles. So it takes time to make this grease in open kettle production.
So the final patent I want to talk about in the development of how you make lithium complex greases was actually about ten years later, a scientist by the name of Carly and some associates developed some technology in a us patent where they avoided the. Avoided the. They avoided the use of two heating and cooling cycles and they used only the acid forms. They added both of the twelve hydroxy stearic acid and the dicarboxylic shorter chain acid. They primarily used azelaic in initial portion of the base oil, and then they added aqueous lithium hydroxide very slowly in a metered process. And the patent discusses why this worked. And it has to do with reaction kinetics.
And by doing this he was able to get the reaction, heat it up to a top temperature of around 204 celsius one time, cool it back down with rapid quenching finish degrees, and they got great dropping points greater than 260 degrees celsius. And the twelve hydroxysteric acid to azelaic ratio. The thickener acid ratio was around 2.6 or lower. They got great dropping points. They didn't use esters, alcohols were not released, and they only had one heating and cooling cycle. The only drawback was you had to really, really control the addition of the lithium hydroxide here in order to make this thing work. And again, they explain why. And it all boils down to reaction kinetics, so that you don't form things so quickly that you can't get good co crystallization. Again, it's all about the co crystallization.
So that's really how the initial lithium complex grease technology, both formulation and manufacturing, initially formed. Now, of course, we had contactors. Contactors have actually been around for a lot longer than people realize. They were already well in existence when the first true lithium complex high dropping point patent existed. With contactors, of course, you recycle like this from the bottom to top, you have a high speed impeller on the bottom, you get really good shearing. As a result, you can form lithium soap and lithium complex grease soaps with one heating and cooling cycle. Again, it's because you have that high shear zone on the bottom with lithium complex greases, and that allows you to affect that really good co crystallization without having to go with all kinds of gymnastics to try to get that co crystallization to occur. But that's really the initial story of lithium complex greases, in terms of both their formulation and in terms of how they were manufactured.
[00:23:02] Speaker A: Yeah, that's really interesting, and it's always nice to have that sort of background. Maybe just something for our viewers to better understand. You've touched on open kettle and contactors as being two of the different production methods for grease. We've obviously also got inline grease units, which are probably the more modern version for mass production.
If you wouldn't mind, do you mind just giving a brief summary of those kind of three technologies and some of like the, maybe the differences between the two in terms of manufacturing?
[00:23:38] Speaker B: Sure. You have open. Well, the three are open kettle production, contactors and continuous. And I've already spoken a little bit about open kettle. All the patents I discussed, all five of them, were only for open kettle production. Contactors weren't even mentioned. They were around, but they weren't mentioned, however, it was not a. It was not a really difficult thing to adapt contactors to make lithium complex greases. They were already being used to make simple lithium soaked greases.
Now, with regard to the advantage, again, contactors are much faster material. By the very nature of the design. You have an annular structure, you have an outer shell, most of the volumes on the inside. And what you have is a circular motion propeller on the bottom and impeller. And the grease basically goes like this in a two dimensional cross section, and you get rapid heating, so you're able to rapidly form the thickener, dehydrate it, and then once the thickener base greases form, it's pumped to a finishing kettle where it's cool. Additional base oil is added, degrade additives are added, and, you know, the advantages are you will get better yields with contactors, and it's a faster process. But of course, not everybody back then, and even today, not everybody has access to contactors.
I really don't know, quite frankly, how it breaks down in terms of world grease production. Open kettle, lithium grease versus contactor, I don't know what the percentage is. There might be other people that have a better idea on that. Now, with regard to continuous, continuous grease manufacturing was first developed and discussed both first in patents and then in a paper LGI spokesman in the 1960s. And of course, it was pioneered by Texaco.
And there were a number of very well known Texaco scientists and engineers that put this together. It really is a very significant piece of engineering to make this work. So you can continuously make lithium soap releases, and then it wasn't very long until they were able to adapt it so that you could continuously make lithium complex creases.
Now, the advantage of that, obviously, is that, you know, you just start the ball rolling, and it just keeps cranking until you want to stop. And again, you can get good yields. But the real payoff for continuous grease manufacturing is this very tiny fish.
By doing this properly, I mean, you can really crank the lithium greases out in a very time efficient fashion. Now, originally, Texaco basically owned the shop with regard to continuous grease manufacturing. Other companies developed their own modifications of that in the ensuing years. So there are other variations on that theme, but really, those are the three ways that you make lithium based greases, and all three are still being used today.
[00:27:00] Speaker A: Yeah, awesome. Thanks for that. Thanks for that overview. So I think that gives us a really good lineage of kind of the history, the pattern history that goes into the different ways to create lithium complex greases. And we've got the three manufacturing methods as well. So now we're starting to kind of get into, like, lithium complex grease manufacturing 102 instead of 101.
My understanding there's a little bit of history of using kind of boron based additives as part of this process. Would you mind going into a little bit of detail on how that kind of affects the finished product?
[00:27:41] Speaker B: Sure. Absolutely.
First of all, I want to talk a little bit about boric acid itself.
If you go to general chemistry textbooks, they usually write formula for boric acid as h three. Bo three.
I don't like that because that formula implies that boric acid is a bronze state acid. In fact, it's not those three hydrogens. Even the very first one will not come off in a bronsted Lowry acid base reaction unless you hit that thing with an amount of chemical force. That's just ridiculous. Under all conditions by which you make Reese's, none of those hydrogens are coming off. In fact, boric acid is not a bronsted acid under most reasonable conditions. It is, however, a Lewis acid because that boron is bonded to three oh groups, which is why I like to use the formula for warric acid, b and then oh in parentheses with a sub three underneath the parentheses close. So it's boh taken three times. That emphasizes the fact that that boron short an electron pair and is therefore rather electrophilic. It's a Lewis acid, it's an electron paired acceptor. And that really defines boric acid chemistry.
And boric acid can be used to elevate the dropping point of simple lithium twelve hydroxy stearate greases. And there are two ways this can happen. You can actually use the boric acid itself, or you can take various organic compounds with various functional groups, react those organic compounds separately with the boric acid to obtain the borated form of those organic compounds, and then take those borated organic compounds as an additive and add it to the lithium soap grease during the final stages, preferably during the final stages of its manufacturing. And that will elevate the dropping point as well. So with that, I'll talk about two key patterns regarding the use of boric acid itself, and then we'll talk about those organic borated additives. The first patent that I know of that used boric acid per se to elevate the dropping point of lithium. Twelve hydroxysterate greases. And they need to be twelve hydroxysteric acid greases. This doesn't work very well with lithium. Stearate was issued, actually in 1973. The inventor was a man named Harding and he actually used twelve hydroxy stearic acid, boric acid and lithium hydroxide. He had an aqueous solution of lithium hydroxide and boric acid, which he added to twelve hydroxycharic acid in an initial portion of the base oil. And then that mixture was heated ultimately to around 200 degrees celsius to form the thickener and reactant. And the initial base oil was added upon cooling. Now Harding said that sometimes it was useful to add another outshield acid and the one he liked to use the most was salicylic acid. I can't help but wonder if aspirin would have also worked. But at any rate, he got dropping points anywhere from about 251 degrees celsius all the way to about greater than 260 degrees celsius. So he was able to get bona fide lithium complex dropping points without using any shoulder chain dicarboxylic acids. Now, about ten years later, another patent issued. The inventor of that was a gentleman named Statler. And once again he used the same materials, twelve hydroxy stearic acid, boric acid and lithium hydroxide. And but he also used a polyhydric alcohol and preferably he used glycerol or, and the patent refers to it as cis dihydroxybenzane. Now, I must tell you as a nitpickler, a nitpicker on chemistry nomenclature, cis is not the right word. He actually meant orthodihydroxybenzene. Cis trans isomerism is not used for substituted benzenes. You use portho, meta and para. The patent says cis dihydroxybenzene, but he actually meant portho dihydroxybenzene. But what he did was the aqueous lithium hydroxide in boric acid was added to the twelve hydroxy stearic acid in a portion of the base oil in the presence of that glycerol or ortho dihydroxybenzene. And the mixture was then ultimately heated to 199 celsius, 200 celsius to fully react and dehydrate. It was cooled.
Additional oil was added to grade to penetration ranges as needed, finished by adding whatever additives you wanted. And the dropping points were good. They ranged from 261 to greater than 315 degrees celsius when they used the polyhydric alcohol.
When they didn't use it, the dropping points were lower, 218 to 228 degrees celsius based on the reported information in the patent. So those are the two key patents that initially used boric acid as a means to avoid using the shorter chain dicarboxylic acids to make high dropping point lithium based rhesus.
Now, the other approach is to take the boric acid and separately react it with certain classes of organic compounds, each of which will have a functional group for which the boric acid can react with.
And those were represented by a series of at least 16 us patents that I've been able to find. And they're all by the same group of mobile oil company scientists. This was done before the ExxonMobil merger. And the inventors were Donner, Haradisky and Keller.
Now, I don't know whether the gentleman pronounced his name Donner or Donner. I'm going to go with the german pronunciation of Donner.
But either way, these 16 patents really defined this entire approach. And each patent basically took a different functional group. An organic material with a different functional group reacted it with boric acid. And then that was added as an additive to a simple lithium soap grease to elevate the dropping point. So you'll have patents where you have borated manic bases, or borated epoxides, or borated alcohols, or borated amides or borated amines or borated oxozolones, just to mention a few.
And each one of these patents, basically as a group, they lock this technology up.
The patents did allow for certain optional organic sulfur phosphorus materials. The most common was zinc bathiophosphates to be used in conjunction with the addition of these borated organic materials in order to further facilitate the increase of the dropping point.
They got dropping points as high as 327 degrees celsius. And again, it was done without using any of the shoulder chain dicarboxylic acids that had defined high dropping point lithium complex cases in those earlier patents that I mentioned.
Now, how do these work? Well, the patents all taught one thing in common, that it was better to use these organic materials if they were overborated. And by that, what the inventors meant was you reacted more than 1 mol of the boric acid with one molar moiety of the functional group in the organic material. And what this was doing, by virtue of the Lewis acid properties of the boric acid, was it was having the boric acid react with the functional groups, but then having more boric acid react with the boric acid that's reacting with the functional groups to form oxygen boron oxygen linkages. And these extended linkages became very reactive, so that when you added them to the lithium twelve hydroxysterate, you could get very easy reactions of those boron boron oxygen oxygen boron oxygen linkages with probably the oxygen in the twelve hydroxy sterate to start cross linking the various lithium twelve hydroxysterate groups. Now, if you start cross linking the various lithium twelve hydroxy stearate groups of the so called simple lithium salt grease, well, what would you expect would happen to the structure of the thickener, the lithium twelve hydroxy stearate thickener, if you start cross linking the individual thickener molecules? Well, you would expect the dropping point to go up because you're interlocking things and forming a more intimate three dimensional molecular network. That's exactly what happens, and that's very likely how this chemistry works. Now, I will tell you that while these patents were enforced, not a lot of documentation in the published non patent literature was being published.
However, when these patents started to expire, we started to get papers being published in, in the open literature, especially in the NLGI spokesman. The first of those papers that I've been able to find was actually published in the September October issue of the 2010 NLGI spokesman. It was published by a friend of mine, John Lorrimore. But there have been a number of papers that have been published since then, and a number of major additive companies now market various organic boron materials that are marketed for use to elevate the dropping point of lithium showcases. Many of these materials have secondary functions. Some of them are very good rust inhibitors, some of them are good oxidation inhibitors, some of them are good anti wear additives, and some of them have more than one of those. So, depending on your choice of organic borinated material, you can actually double or triple dip the functionality that you're adding to the lithium soaked grease. So that's really the story of how these boron based chemistries have been used to elevate the dropping point of lithium sulfur. And I will tell you, the combinations of using shorter chain dicarboxylic acids and boron chemistry have also been used. Basically, you put in some boron chemistry and you don't want to bring the dropping point all the way up, but you bring it up enough so that you don't have to use nearly as much of the dicarboxylic acid. And that approach has been used as well.
[00:39:58] Speaker A: Yeah. Wow. Absolutely fascinating. It's one of those things where you see, you see boron additives kind of listed everywhere, but without that sort of like, deeper understanding of their genesis and where they come from. So maybe it'd be helpful to understand. We've already talked about sort of like, heating and cooling cycles and things like that. But what are the kind of the limitations that we've run up against in terms of manufacturing processes even? Are there specific additives that aren't really compatible with the manufacturing process? And that's why we don't see them in lithium complex greases? Like at what point do you kind of run up against the, the bounds of physics and chemistry?
[00:40:42] Speaker B: Okay, good question. Well, and I touched on this a little bit in the last podcast, but let's go into a little bit more detail now.
First of all, additives, functional additives, to either introduce new properties into the grease that the base grease doesn't have at all, or to enhance properties that the base grease has at a low level, but you want them be more profound.
Both additives are typically added at the end of the grease making process after the thickener has been formed. After the thickener fiber structure has been formed, the grease has been cooled down, and basically the base grease structure is pretty much carved in concrete.
Additive temperature the temperatures in which the additives are added are typically going to be somewhere, and I'm speaking around numbers here, 77 to 93 degrees celsius would not be a bad range of temperatures to which additives can be added. There can be exceptions to that.
Most of the additives that can be used in greases are going to be compatible with lithium soap greases as well. Now you want to make sure that the additives don't harm the thickener fiber structure. As I mentioned, high levels of detergent additives are probably not a good idea.
One interesting limitation is if you're going to use the boron chemistry approach to make a lithium complex grease a high dropping point lithium grease, you probably want to make sure you make your lithium grease using twelve hydroxysteric acid and not use hydrogenated castor oil. Now, hydrogenated castor oil is primarily composed of glycerin, primarily with three ester linkages on each glycerin backbone. And those ester linkages are twelve hydroxysteric acid almost entirely. So when you cleave that by hydrolysis, if you use hco, hydrogen and castorol to make your lithium so crease, we'll react it in water with the lithium hydroxide. The water will hydrolyze the hco, release the twelve hydroxy stearic acid, which will promptly react with the lithium hydroxide to form the lithium twelve hydroxy stearate. Then you dehydrate that to get rid of the waters of reaction and the water that you added. But you're going to be ending up with glycerin in your grease.
If you use twelve hydroxysteric acid, there will be no glycerin in grease. Now, why can this be an issue? Well, it's been determined that if you make a simple lithium salt grease using hco and then try to use the boric acid trick at the end, you don't get much of a dropping point increase.
The reason is the boric acid preferentially reacts with the glycerin in the grease.
And that prevents what you want to have happen in terms of boric acid forming oxygen boron oxygen extended linkages between the various lithium twelve hydroxy sterate units. Now, what's really interesting about this is it's been shown that if you separately react glycerin with boric acid properly and then add the borated glycerin as an additive at the end to a simple lithium soap grease made with twelve hydroxyzuric acid, you can elevate the dropping point. So think about that one for a while. That gives you just an idea of the molecular complexities of processes that are going on here. There's still some stuff that we really don't know everything about.
Now, I also want to talk a little bit about polymers.
Polymers, or one of those areas where depending on what kind of polymer you're using and how you use it, you can have problems. Traditionally, polymers were the non reactive type and they were traditionally added at the end with every other additive. And polymers were used to modify the rheology. Especially the high molecular weight polymers would be used to provide straininess and tackiness. If you use polymers in that way to provide stringiness and tackiness, you get your best results if you mill the grease first and then add the polymer to it. Because these greases have extremely high molecular weights and are very shear sensitive. And the process of going through a really good colloid mill, which is what's usually used for lithium based greases, will tend to chop those polymers up into much smaller pieces, and then you lose much of the polymer's ability to provide that really stringy, gutty, tacky texture that the polymer is being put in for.
Now in the two thousands we had first in the patent literature, and then in a number in LGI spokesman papers, the introduction of what's called functionalized polymers. Now, these are polymers that have pendant functional groups hanging off of the polymer backbone, usually carboxylic acid groups. And they actually, you add them at the beginning, you add them at the beginning when you form the thicker. Now, you don't want to put these in at the same concentration you put in the non functionalized polymers. If you do that, you're going to end up with a real gelatinous meth on your hands that you can't even manage. These polymers are typically put in at 10% or less of what you put in a non functionalized polymer. And properly used, these can provide some really significant changes to grease rheology, but you have to use them properly using non functionalized polymers. There are not the strainy, tachy level that you can put those in also initially, before you form a thickener. And the reason you do that is so you can get what's called a thickener, polymer entanglement, in which when you form the thickener fiber structures in the presence of these polymers, which at the temperatures of reaction, those polymers have unwound quite a bit. Then you get the thickener fiber and the polymer structure tangled up within one another, and this modifies the overall thickener structure as well.
And again, proper use of this, you can get some very interesting rheology in these greases.
So that's some of the. Some of the, I would say, the high points of what you want to know about how additives can and cannot be used in lithium soaps.
There are other things like to say as well, but that's a good primer for white. Now, I think.
[00:47:51] Speaker A: Yeah, that's awesome. Now, you know, I think that's really helpful to sort of contextualize.
And I always find it fascinating, because coming from the lubricating oil world, grease is a kind of like a whole different beast. It's almost like an entirely different species. And the complexity of having to manage, you know, the additives, the thickener, the bases, and getting all that to coordinate into a single product that can actually function exactly the way that you want over a long period of time. That's kind of what fascinates me about the lubricating greases world. It's definitely a very highly specialized area.
One thing that would be helpful to understand, and usually, as we kind of draw to an end in these podcasts, we'd like to talk a little bit about the future. And, you know, sometimes that really relates to kind of new developments in the field.
You've published in a fair bit of detail, you know, some optimizations around grease manufacturing and ways to, you know, improve properties or decrease the amount of lithium that's required as part of the manufacturing process. That's actually pretty, I'd say, pretty topical. Obviously, we've had a little bit of relief in lithium prices recently compared to a couple of years ago. But with battery demand being what it is, it's very likely that at some stage we'll see a spike in lithium price in the future. And so manufacturers are always looking to optimize on cost, but also improve yield. So, could you talk a little bit about some of that sort of work that you've been doing and what are kind of, some of the levers that we can pull to really help us in that process?
[00:49:46] Speaker B: Sure. Be happy to. Well, to do that, I want to go back and I promised I was going to do this. Let's talk about the thickener acid ratio, that is to say, the weight weight ratio of the amount of one chain monocarboxylic acid use relative to the weight of the shorter chain dicarboxylic acid you use for a traditional non boronated lithium complex grease. Now consider these facts.
If you do the stoichiometry.
Each pound of twelve hydroxy stearic acid requires 0.14 pounds lithium hydroxide monohydrate to react and neutralize it.
One pound of azelaic acid short chain dicarboxylic acid. That requires not 0.14 pounds of lithium hydroxide monohydrate, but 0.46 pounds of lithium hydroxide monohydrate. In other words, a bit over three times as much. Okay, now consider this. As I mentioned in the previous podcast, it's the lithium twelve hydroxy stearate lithium long chain fatty acid salt that's responsible for the thickening the dilithium salt of the shorter chain dicarboxylic acid. Azelaic acid isn't a good thickener. It's there for only one reason, to raise the dropping point. In fact, as you add the dilithium azalate to the structure, you actually require so much of it. And what it does, it actually dilutes the effect of the simple lithium salt salt, so that not only do you add this dilithium salt that requires more than three times lithium to react with it, but you're actually now going to be requiring even more lithium for the lithium, for the twelve hydroxy stearing acid as well. So you're getting hit with a double whammy to make a lithium complex grease in terms of the required lithium. So any method that can reduce the amount of the shorter chain dicarboxylic acid relative to the longer chain monocarboxylic acid, or in other words, anything that can increase the ratio of the long chain to the short chain nico oxalic acid, can be expected to reduce the required amount of lithium. And it's going to do that in at least two ways. First of all, by reducing the amount of azelaic acid relative to twelve hydroxysteric acid, you're reducing the amount of lithium needed because azelaic acid requires more than three times as much lithium to neutralize it. But it's doing something else as well.
The more you lower the amount of baseline gas in your lithium complex grease structure, the more lithium complex thickener starts to resemble a simple lithium. So grease and that improves thickener yield. And when you improve the thickener yield, you need less thickener and you need less lithium for the twelve hydroxy steric acid portion.
So you might say, well, that's easy, just use a lot less azelaic acid. Well, unfortunately, that's a problem because it's the azelaic acids that's raising the dropping point. There's a reason why thickener acid ratios in the literature prior to my work were never reported any higher than 3.2.
Because if you go any higher than that with the old technologies that I've discussed, your dropping point craters. So what we need is some new technology that allows you to have the best of both worlds. Quote candy so what you want is something that allows you to dramatically reduce the azelaic acid content relative to the twelve hydroxy steric acid content and keep that dropping point and all other thickener related properties of grease where they are. And that's what I did with my new technology that I developed. Now, in this new formulation approach, here's how it works. You add an initial portion of the base oil to your kettle.
Then you add a small amount of an arylamine antioxidant. That's not actually key to the invention, it's simply, it's just a good idea. You're going to be heating this grease up to 204 degrees celsius. You don't want the base oil to oxidize like crazy. So you put in an antioxidant at the beginning. That's all that's there. Then you add, and here's the secret sauce, you add about a half a percent, based on the total weight of the final grease, of a 400 total base number over base, magnesium sulfonate. And then you add water and the appropriate amount of lithium hydroxide monohydrate to react with over the acid you're going to add.
Now, notice right from the beginning, we're doing something different. In all the other technologies I mentioned, all the prior patent technology, you always add lithium hydroxide to the acids in this technology, you put the lithium hydroxide in first and we're going to add acids later to hit, so it's in reverse.
Then you heat the material up to about 82 to 88 celsius. And then you add the two acids, the twelve hsA.
And within 1 minute of adding the twelve hydroxy steric acid to this mixture, you have a heavy grease and ftir will show within five minutes that it's fully reacted. There's no twelve HSa left, but you don't wait that long. After about a minute, then you add the azelaic acid and boom, it reacts to you let it go for about 45 minutes just to make sure that everything is fully reacted. And then you heat it one time, up to 204 degrees celsius, to 210 degrees celsius. You hold for five minutes to dehydrate, ensure things reacted, and then you begin cooling.
And after you cool it down a bit, you add more base oil. You wait until the grease reforms. This gets really heavy. Then you add more base oil. You can speed up the cooling process from there. You have to add more base oil because you don't want to become so thick that you have a problem with heat transfer and mixing. You never want to have that problem. And then you cool it to about 77 degrees celsius as per typical grease. Add more base oil as needed to get it within pin range. Add your additives, milk, boom, you're done. That's really how you do it, and it works. Now, if you look at that process graphically, you're going to see just one heating and cooling cycle and you're adding the acids to the base, not the other way around.
And you're adding the acids one tray after the other with no essential delay at all. And it works really, really well.
But why? Why is it working well? Consider the following logical sequence of facts.
I told you, the magnesium overbased sulfonate is the secret sauce and it is overbased. Magnesium sulfonate is an excellent detergent disperser. Lithium hydroxide is a much stronger base than any of the magnesium bases that you're going to see in that overbased magnesium sulfonate, namely magnesium oxide, or magnesium hydroxide or magnesium carbonate. Lithium hydroxide is a far stronger base than any of those.
Also, there is far more lithium hydroxide than the overbase magnesium sulfonate and way more lithium hydroxide than the basic materials in the overbase magnesium sulfonate. Lithium hydroxide is very soluble in water overbased magnesium sulfonate and its basic components are not soluble in water.
By the time your temperature reaches 82 degrees celsius and you're ready to add the acids, that water is already very well dispersed because of the dispersancy of the over base magnesium sulfonate. And the water will be saturated with lithium hydroxide and the rest of the lithium hydroxide is disposed in the oil. Again, because of the over based magnesium sulfony, the amount of magnesium base, again is very tiny compared to the overwhelming amount of the strong base lithium hydroxide. So when you have those thick, those thickener acids, twelve hsa and then azelaic, they're going to react immediately with the lithium hydroxide and they're not even going to touch that little bit of overbase magnesium sulfonate as the brick thickener performs as the lithium twelve hydroxy steroid and the dilithium azylate form, the overbased magnesium sulfonate is going to disperse it into the thickener structure, which is why you get an instant heavy grease.
Now that's really what's going on. Now, I won't go into this. I wrote a paper on this and it's also in the patent that covers this. If you add too much overbased magnesium sulfonate, you disperse the thickener so well that you end up with an oil instead of a grease.
If you add too little of overbased magnesium sulfonate, you basically get a poor thickener yield. And again, you start shooting yourself in the foot with regard to the amount lithium hydroxide that you need. So this is very definitely a Goldilocks situation. You don't want too much, you don't want too little, you want it just right. And if you do that, you can. What happens is that overbased magnesium sulfony facilitates that really efficient co crystallization of the lithium twelve hydroxy stearate and the dilithium azalea. So in fact, it facilitates such an excellent and rigorous co crystallization that you don't need nearly as much of the azelaic acid to do the job.
And that's why it works. Now, when does this co crystallization occur? Now you might go, well, I know, you form that initial grease structure so fast. That's when the initial, that's when all that co crystallization occurs. No, again, read my paper or the patent. That's not true.
When you heat that up to around 204, you melt the lithium twelve hydroxy sterate portion. I show very rigorously that it is when you cool from top temperature down and reform the full grease, that's when co crystallization due to the magnesium over basulfinate does its job, and it does do its job.
How well does it do its job? Well, in the original lab work I showed, you could reduce the lithium content of a grease by 28%, with no deleterious effects on dropping point or anything else.
The grease had dropping points in excess of 300 degrees celsius. Excellent shear stability at 25 and 150 celsius. Four ball ep well loads, 620 kg was normal. Four ball wears of 0.43 or less. Excellent oil bleed. You do it right, you get one b. Copper strips. This has been successfully commercialized, and in commercialization, it works even better. We're seeing reductions in lithium, approaching 40%. Reduction in lithium required, with no reduction in properties at all.
And the reason why it works better when you scale up is because the chemical reaction is clean. It's only one thing. There aren't competing reactions that have a balance of kinetics. As I pointed out in the last podcast, there's only one thing that can happen. And by dramatically improving the mixing in open kettle production, you're able to get even better yields in commercial production. So, I mean, think about it. You're reducing the lithium required without any decrease in the performance. Laboratory properties, you're reducing lithium by up to 40%. That's great. Now, why did I do this? You know, some have suggested I develop this because I want to save lithium soap greases. You know, with the lithium price crisis, lithium, the share of lithium greases, and the global grease production pie is starting to go down for the first time since it went up. And maybe Andy's trying to save lithium. So greases. Not at all.
Not at all.
But if you look at the forecast, nobody is suggesting that because of the lithium price, lithium soap greases are going to go to zero.
Within the foreseeable future, there's still going to be a significant wedge in the global lithium production pie that's going to be due to lithium salt greases.
And for high performance lithium greases, lithium complex greases, it just makes sense to use as little lithium as possible. It's called sustainability, right? That word that everybody loves to use today. That's why I developed this technology.
It has nothing to do with trying to save lithium. It's simply common sense. You know, whatever amount of lithium complex greases are going to be made in the future, let's use as little lithium as possible to make them. And that is really the point of this new technology.
[01:04:04] Speaker A: Yeah, that's fascinating. And I think there's a couple of things which are really interesting to draw from that. I mean, number one, it's just a very cool technology.
Number two, the fact that we're speaking to someone who's actually developed it, that's also extremely cool. But also, when you put it together with our previous discussion, as well as the discussion we've had today, you can sort of trace the lineage of this technology all the way back to the world War two era. And to see that the technology continues to be developed and refined and optimized is just. That's extremely cool to me, to see that sort of direct lineage through all the pattern literature as you've laid out as well. So I find that really interesting.
On the point of lithium demand and all the rest of the sort of the economics that are playing into grease demand, what I see in the market, at least, is the demand for lithium greases is still extremely strong.
You know, at the margins, we're seeing some of it be replaced by the likes of the calcium sulfonate, particularly in the mining industry. So here in Australia, we've obviously got a lot of exposure to mining, and at the margins, we are seeing calcium sulfonate become more popular. But even then, we're coming off such a small base. It's a little bit like the EV adoption curve, right? Yeah. Calcium sulfonate is. Is growing by a substantial amount each year, but when you're coming off a market share of one to 2%, that growth, in absolute terms, is still relatively low. And so, like you said, for the foreseeable future, I don't see the lithium greasers really going anywhere. And so we still need to refine that technology even further. And as we outlined in the previous podcast, you know, lithium greases, the big advantage there is that there is no disadvantage, if you like. And so, again, being that jack of all trades and being, you know, the standard grease for so, so many oems, you know, it's going to take a very, very long time to shift it from its. From its throne.
[01:06:20] Speaker B: Yeah, it won't be happening in my lifetime.
[01:06:23] Speaker A: Yeah.
[01:06:26] Speaker B: Interestingly enough, as you know, and anybody that's listening to the previous two podcasts with me knows I love to tell stories, and I've got a good one. And I'd like to finish my portion of this podcast with this story. I started the previous podcast on lithium greases with talking about why 1942 was an important year. And it was a very important year. That was when those classic five Clarins eviral lithium stearate thick and grease patents issued. He actually filed for them in 1941. And they issued the next year.
And Clarence E. Earle is universally considered the father of all lithium based greases, as he should be. But what would you say if I told you he actually wasn't the first person to do it? Because according to Art Pelashuk, and you can read about this in page 202 and 203 of his book, a brief history of lubricating reasons, which is about a quarter of the way through the book, he tells a very interesting story.
And the bottom line is this. In the mid to late 1930s, another respected chemist named Harold M. Frazier was making consistently in the laboratory lithium twelve hydroxy stearate greases. And the story is interesting, and it's even indirectly linked to the invention of nylon, which was one of the most important synthetic synthesis inventions of the 20th century. You can read about this if you go to page 202 and 203 of that book. But here's the interesting thing. Harold M. Frazier's work clearly predated the work that Clarence C. URL did. But for reasons that are not clear, he didn't initially file for a us patent. Now he eventually he did. After Clare C. Earl's patents issued, he filed, and he ultimately got a patent for lithium twelve hydroxy steray greases, three years after Burl's patent was issued in 1945. But he didn't file before that. And maybe it had something to do with World War two, but nobody knows for sure.
The bottom line is this. He didn't publish. He didn't file for the patents. Clarence E. Earl, who did lithium steroid Greece, as later did, and in the industrial world as well. In academic as publisher Parish, Clara C. Hurrell is considered the inventor of lithium based greases, even though somebody else did it first. And Polishock knew Harold Frazier personally. There's no reason to disbelieve the story that Polishuck tells in his book, and I believe it's true.
So, you know, it's kind of interesting. People might think that that's a little unfair, but actually it's not. It's very fair, because science works by advances being published in the open literature, so that other scientists can digest it, build on it, and then they make contributions, which then can be the source of the process being repeated over and over again. And when you don't publish, for whatever reason, it could be company policy. Whatever you don't publish, you're short circuiting the scientific process.
So Harold M. Frazier might have been first doing the laboratory, but Clarence E. Berle is the father of lithium based greases, and, you know, one of the most prestigious awards that any lubricating Greece scientist can achieve is the clear sea for all memorial awards. I have several friends who have received that very important award.
And, you know, if Harold M. Frazier had, for whatever reason that prevented him, if he had actually filed for a patent or even published a paper before Clara C. Earl filed for his patents, that award might be known as the Harold M. Frazier Memorial Award. But it's not. And if you think that's still unfair, if you are asked the question who discovered the double helix structure of DNA? Everybody's going to say Watson and Crick. And I believe that is true. But if you've read the story, you know, there is at least some controversy as to whether or not Watson and Crick or a competing team might have actually discovered it first. But it doesn't matter, because Washington Cricket submitted their results for publication first, and that's all that matters. And the two of them have Nobel Prize medallions. They can hang around their neck as proof that that's the only thing that matters. So the moral of this story is, publish.
Find a way, whatever. When you find. When you do something inventive, innovative, figure out a way, beg, borrow, or steal, whatever it takes, publishing the literature so that science can move forward.
[01:11:50] Speaker A: Yeah, that's a. That's a really great note to sort of end on. And what's. What's I find hilarious is that that book, the art polish act book, I've actually tried to get ahold of it, but it's not in print anymore. But you did hold it up in. In the previous episode, this brief history of lubricating greases.
[01:12:09] Speaker B: And.
[01:12:09] Speaker A: And it's like hitting someone with the encyclopedia Britannica.
So if you do happen to have a copy of that book, first of all, reach out, because I'd like to buy it off you, but also hang onto it because it's no longer in print and it's pretty hard to get a copy of it. But hey, Andy, your insight is always awesome. Everyone really enjoys the way that you kind of lay out not only the technology, but the story behind the technology, and also giving credit to all these people who contributed to the corpus of knowledge as well. So I think everyone really appreciates that. So, once again, thank you for your time, and we'll talk soon.
[01:12:51] Speaker B: Take care.
Bye.
