A DISCUSSION OF PETROLEUM SULFONATE IN LUBRICANTS - PART II: BARIUM SULFONATES AND ALOX PACKAGES

Vietnam has a forth wave of COVID-19, and the situation become worst in Ho Chi Minh City now. I cannot pay a visit to my customers, what I can do is online communication and telesales… Thus, I can have time to continue write the topic: A DISCUSSION OF PETROLEUM SULFONATE IN LUBRICANTS. After having a quick review on Ca Sulfonate with the typical products of CHEMTURA (LANXESS), today I would like to talk about Barium Petroleum Sulfonate and several famous commercial packages for Rust Preventative Oil in combination with some components from CRODA, LANXESS.

 

Actually, sulfonate metal soaps can be described as detergents, which must contain metal in the structure to distinguish with dispersants that are ashless or metal-free. The common metal used to synthesize detergents can be: Li, Na, K for group IA; Mg, Ca, Sr, and Ba for group IIA in the periodic table; and Al for group IIIA. The raw materials are sulfonic petroleum sulfonic acid (organic acids) and metal oxide or metal hydroxide (inorganic compounds); they are not easy to react because of the poor contact between two phases. One phase is hydrophilic and the other is hydrophobic. Therefore, to accelerate the reaction, there are one or many compounds which is called “promoters” are employed. Some common promoters consist of alcohol (methanol, ethanol, butanol), NH₄OH, alkanolamine, low molecular weight carboxylic acid (i.e. formic acid and acetic acid), and low molecular weight alkylphenols. Those promoters are mentioned as a coupling agent to enhance the contact between two phases and help the reaction occur.

 

Detergents can be made in neutral and over-based forms. Neutral detergents provide higher content of sulfonate soaps, which provide better corrosion protection properties because it can provide maximum metal surface coverage at the lower treat-rate than that of over-based ones. Over-based detergents consist less sulfonate soap content, but it is enhanced base number through the colloid CaCO₃/Ca)OH)₂. Thus, it will provide better acid scavengers and long-term corrosion protection in some applications where acids are one of the serious issues (e.g., engine oil, marine oil). Of course, in both mentioned cases we have not mentioned on the MW of sulfonate. The better corrosion inhibitors are affected by many parameters such as: sulfonic acid MW, the coverage on metal surface (depends on the numbers of molecules sticks on the metal surface), and the TBN value. Depending on the specific applications and the manufacturer’s design for sulfonate soaps, the specific additive can be used for some specific applications.

 I.  BARIUM SULFONATE COMPONENTS

Ba Sulfonate can be prepared in both neutral and overbased soaps. It can be prepared from natural sources or synthetic alkylbenzen sulfonic acid including monoalkylated compounds (C16-C40) and alkynaphthalene derivatives (i.e., dinonyl naphthalene sulfonic acid). Both natural and synthetic Ba sulfonates show outstanding corrosion protection in formula for rust preventative oils. Ba dinonyl naphthalene sulfonate works well at low concentration in contrast to Ca and Na. This is directly proportional to an increase of ionic radius: Na < Mg < Ca < Ba.

There are several manufactuers to produce Ba Sulfonate around the world, but some of them are very strong for this products in term of product stability and reputation (i.e., Lubrizol, King Industry, Lanxess). Since it is hard to find some technical data sheets from reliable manufacturers, I choose LANXESS Ba Sulfonate to discuss in this part.

Table 1: Typical physical properties of LANXESS Ba Sulfonate

Property	Surchem 404	Surchem 404D	Barinate B70
Ba wt%	6.6	6.6	14
Ba Sulfonate wt%	49	49	43
Equivalent Weight	500	500	500
TBN	4	4	68
Vis@100 cSt	110	110	40
Flash Point COC	220	220	190
Water demulsibility	-	Pass	Pass
Cu corrosion	1b	1b	1b

Note: The different between Surchem 404 and 404D is that Surchem 404D has already added a small amount of demulsifier, so it will provide better water demulsibility than that of Surchem 404.

Surchem 404/404D has the same MW to Barinate B70, but the content of Ba soaps are slightly higher than B70. In addition, the vis@100 deg C of 404 series is much thicker than B70, hypothesizing that they will provide a thicker film on the metal surface at the same treat rate ==> better corrosion protection properties. If I am a formulator, I may use 404 series for RP oils to use in the neutral atmosphere without acid vapours. However, if I would like to make the RP oils for acidic atmospheres in the workshops because of acidic cleaning process,  I prefer B70 over 404 series because it contains high TBN value. 

II. BARIUM SULFONATE IN PACKAGES

If you work on RP oils, you may know the reputation of LUBRIZOL for ALOX packages. So, I will talk about ALOX packages since we are also selling ALOX 2100 and 2028S packages in Vietnam. Basically, I was educated in university within 6 years and I have worked as a salesman in Vietnam for lubricant additive since Sep. 2016, so I would like to discuss in scientific points of views. 

There are many reasons why ALOX packages can have good reputation in lubricant industries. It has been showed on the market of Korea, Taiwan, and China as well. For other market, I do not really know, but I strongly believed that it will be one of the leaders for RP oils. In addition, ALOX packages (i.e., ALOX 2028S) in combination with Pentalan 1 (CRODA), Calcinate C-300R, PIB-tackifiers can provide super good performance for long-lasting salt spray test. This formula works quite well in Taiwan and Korea, and it may work well in Indonesia as well since the biggest consumption of Pentalan 1 of CRODA coming from Indonesia (this is the information shared by my friend, it needs somebody in Indonesia to confirm this).

However, the use of ALOX 2028S has a drawback is that the applied metal parts cannot be exported to the US and EU since it contains Barium inside. As a result, when customers want to export to those areas, we always recommend them to select ALOX 2100 which just contains Ca without Ba.

                               Table 2: ALOX 2100 Basic Formula for Reference

  

There are two important parameters of RP oils. They are ASTM B117 (salt spray) and ASTM D1740. The others (water separation and water displacement) are also crucial. For ASTM B117, there is no standard specimens, so technician can use whatever metal parts with different shapes are ok. Thus, in my perspective, ASTM B117 is just a method for reference and make a comparison between/among many RP oils with the required metal parts of end-users. Some custosmers contact me said that why the result of ALOX 2100 20% + 80% petroleum solvent cannot reach the result of 168 hours... as claimed in the TDS... Here, we need to make it clear that the metal parts in the test showed in TDS of ALOX 2100 is Sand Blasted Steel Panels, so if end-users run the test with the same materical and shape, the result may be the same, but different materials and shapes can completely give different results. To cut the long story short, ASTM B117 is an effective tool to compare 2 or more RP oils at the same test conditions: same metal parts, same NaCl concentration,...

Figure 1: Test Specimens in ASTM B117 

(to be continued)

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