EP additives: Regulatory updates of chlorinated paraffins and options on alternatives

Dr. Neil Canter, Contributing Editor | TLT Tech Beat September 2014

As agencies worldwide examine how these substances will be governed, formulators search for alternative solutions.

KEY CONCEPTS
• There are no restrictions on the use of MCCP and LCCP chlorinated paraffins though they continue to be under regulatory assessment.
• A newly commercialized type of chlorinated paraffin known as vLCCP is available and not under regulatory assessment at this time.
• A number of alternative EP additives are available for use as replacements for chlorinated paraffins.
• Alternative EP additives can be used in synergistic combinations and also in combination with boundary lubricity additives to provide comparable performance to chlorinated paraffins.

CHLORINATED PARAFFINS ARE ONE OF A NUMBER OF EXTREME PRESSURE additives used to boost the performance of metalworking fluids in specific applications. A good deal of confusion exists in the marketplace about whether chlorinated paraffins can be used commercially and, if so, which types are available.

Extreme pressure (EP) additives are a specific class of boundary lubricity additives that either react with the metal surface to form a metal salt layer under extreme boundary lubrication conditions or form a carbonated film between two metal surfaces under severe lubrication conditions (1). The first part of this definition refers to compounds based on chlorine, phosphorus and sulfur that all react or become activated within a specific temperature range. The second part of the definition refers to overbased sulfonates that form a carbonated film independent of temperature.

To draw a distinction, boundary lubricity additives typically are based on fatty oils and their derivatives (2). In a previous TLT article, the contributors in general believe that boundary lubricity additives adhere to the metal surface and impart a physical boundary between contacting surfaces.

The difference in the operating temperature ranges for boundary lubricity additives and the three types of EP additives are shown in Figure 1. Chlorinated and phosphorus compounds display similar activation temperatures while sulfur compounds activate at a higher temperature.


Figure 1. Operating temperature ranges for boundary lubricity additives and three types of EP additives run from 0 to 1,000 C. (Courtesy of The Lubrizol Corp.)

The purpose of this article is to (1.) provide an update on the regulatory status of chlorinated paraffins among the appropriate governmental agencies, (2.) discuss how best to use this EP additive type in metalworking fluid applications and (3.) present information on alternative EP additives that can be used in place of chlorinated paraffins.

CHLORINATED PARAFFINS
Input on the current status of chlorinated paraffins has been obtained by Andrew Jaques, manager of the Chlorinated Paraffins Industry Association in Washington, D.C. A perspective on how metalworking fluid (MWF) formulators should use chlorinated paraffins is provided by STLE member James MacNeil, product manager for Qualice LLC in Hamlet, N.C.

The three traditional categories of chlorinated paraffins—short-chain (SCCP), medium-chain (MCCP) and long-chain (LCCP)—are listed in Table 1. Chlorinated paraffins are available with specific chlorine contents and at particular viscosities.


Table 1. The chain lengths for the traditional three chlorinated paraffin categories are shown. (Courtesy of Chemical Solutions)

Jaques indicates that chlorinated paraffins are used in MWFs because they are a proven technology. He adds, “My understanding is that each metalworking operation requires specific fluid characteristics depending on the metal, operational condition, etc. Chlorinated paraffins are part of that equation. When Environmental Canada had its public stakeholders meeting a few years ago, one of the clear messages from the metalworking industry in Canada is there are no real substitutes for chlorinated paraffins in some metalworking operations. This same message was also delivered by ILMA to the U.S. EPA several years ago.”

MacNeil indicates that the major benefits in using chlorinated paraffins are reduced tool wear and improved parts finish. He says, “There has to be a balance between chlorine content and viscosity. Chlorine can deplete during use in some applications, so there has to be enough present in the metalworking fluid to provide an adequate useful lifetime. A viscosity needs to be chosen that is appropriate for the operation.”

From an application standpoint, MacNeil contends that chlorinated paraffins are beneficial in almost every metalworking operation. “The value of chlorinated paraffins is that they can increase tool life, a critical parameter for almost every machine shop,” he says. “They are extremely cost-effective, and they have been extensively tested from a health, safety and environmental perspective. Furthermore, there are operations involving very hard metals, deep drawing or severe metal removal that can only be performed using chlorinated paraffins to increase the extreme pressure performance of the lubricant.”

REGULATORY STATUS
As Jaques indicates in a recent article (3), chlorinated paraffins have been under evaluation in the U.S. since the late 1970s. Within the past few years, SCCP has been restricted or prohibited in the U.S., Canada and the European Union (EU). This has led to concern in the metalworking fluid industry about the status of MCCP and LCCP.

Says Jaques: “Currently, there are no restrictions on the use of MCCP and LCCP products in the U.S., Canada and the EU. It is difficult to predict whether this will ever change in the future. There have not been any restrictions proposed, though assessments are ongoing by EPA and others. The regulatory landscape is constantly shifting, so the best advice I can give a metalworking fluid formulator or any chemical product formulator is to make sure you have the most current regulatory information from your chlorinated paraffin supplier.”

EPA is currently undertaking risk assessments on MCCP and LCCP. This process has been ongoing since March 2012, and there is no indication when EPA will prepare and release its findings. Jaques provides his perspective on EPA’s possible actions. “The issue of possible future restrictions is a complex one and will not be decided quickly,” he says. “There are no restrictions currently being proposed by EPA on the use of MCCP and LCCP in metalworking fluids. EPA is considering requiring additional environmental fate testing that will take some time to complete and assess before risk management decisions can be made. Recent research suggests that chain length may not be the only consideration when it comes to assessment of the environmental assessment of these chemicals.”

Jaques is optimistic that some type of chlorinated paraffin will be available to the metalworking fluid industry. He says, “New research we just conducted in the EU shows that moderately chlorinated MCCPs (up to approximately 50 percent chlorination by weight) will readily biodegrade. In fact, while the European Chemicals Agency (ECHA) is still pressing industry to do more testing on MCCP, it is now focusing exclusively on the higher chlorinated versions of MCCP and have concluded that MCCPs up to 50 percent chlorinated (by weight) are not Persistent, Bioaccumulative and Toxic (PBTs) substances.”

vLCCP
In moving forward, a new chlorinated paraffin category has been commercialized. MacNeil says, “Chlorinated paraffins with chain lengths greater than C20 are now available. These are known as very long-chain chlorinated paraffins (vLCCP).

Table 2 shows the current chain lengths for the four chlorinated paraffin categories. vLCCP are now defined as C18-C20. vLCCP have chain lengths at least up to C30.


Table 2. The chain lengths of the four current chlorinated paraffin categories are shown. (Courtesy of Chemical Solutions)

The higher chain length of the vLCCP can present some new challenges to the metalworking fluid formulator. Mac- Neil explains, “The higher viscosity of vLCCPs requires some care in formulating. However, they can be emulsified using standard industry-accepted emulsifiers to create water-based products and have comparable solubility in oil for neat oil formulations. The higher viscosity dictates that the maximum chlorine content of a vLCCP is around 50 percent by weight, as opposed to close to 60 percent for a MCCP. This difference becomes quite small in a formulated product. For example, the 10 percent difference in chlorine content becomes only a 2 percent difference if the chlorinated paraffin is used to a treat rate of 20 percent in the formula.”

Several tests need to be done to evaluate any chlorinated paraffin. Says MacNeil: “The first test is to evaluate the solubility of the chlorinated paraffin in the base oil being used and/or the metalworking fluid concentrate. Then the metalworking fluid can be evaluated using such screening tests as the 4-Ball, microtap and the twist compression.”

Figure 2 shows Twist Compression testing done comparing the results from a neat oil formulated with a MCCP versus two neat oils formulated with vLCCPs. The results show comparable performance for all of the samples.


Figure 2. Twist compression testing shows that two vLCCPs display comparable performance to a MCCP in neat oils. (Courtesy of Qualice LLC)

One added element about vLCCP is their regulatory status in the U.S. MacNeil says, “vLCCP products are fully registered under TSCA and are not under EPA risk assessment at this time. In addition, vLCCP products are also on Canada’s Domestic Substances List.”

ALTERNATIVE EP ADDITIVES
With the concern about chlorinated paraffins, there are alternative EP additives that can be used by metalworking fluid formulators. To further discuss these options, industry representatives from the following companies were interviewed: Afton Chemical, Croda Inc., DIC Corp., The Elco Corp., The Lubrizol Corp., PCC Chemax, Inc. and Rhein Chemie Rheinau GmbH.

Steven Anderson, R&D manager, Global MWF Product Development for Afton Chemical in Manchester, U.K., says that extended boundary lubricity additives can be used as alternatives to chlorinated paraffins. “Modified natural esters provide extended boundary lubrication but do not chemically react with the metal surface in the same manner as chlorinated paraffin,” he says. “This extended performance can overlap with phosphate esters additives and in combination can replace chlorinated paraffin. Phosphorus and sulfur also can be used to provide actual extreme pressure functionality. Some phosphorus-containing antiwear additives such as zinc dialkyldithiophosphate have been used as EP additives in neat oil applications. Oil soluble boron-containing molecules also can be used in neat oils.”

STLE member Dr. Paul Bonner, lubricant applications team leader for Croda Inc. in Snaith, U.K., believes that two different approaches can be used to achieve equivalent or superior performance to chlorinated paraffins in standard cutting and grinding applications. He says, “The first approach is the use of an organic-based lubricity package that optimizes the friction reduction in the metal-cutting process. This low-friction package reduces the temperature of the operation, lowers wear and eliminates the need for chlorinated parafffins.”

Microtap testing shows modified natural esters exhibit comparable and in some cases superior cutting efficiencies to chlorinated paraffin. Evaluation in real-world applications has confirmed these test results.

Bonner says, “The second approach is the development of intricately designed polymeric lubricity additives that work synergistically with existing phosphorus- and sulfur-containing EP additives.” Data showing this synergism is provided in a Reichert study shown in Figure 3.


Figure 3. Reichert testing is shown for chlorinated paraffin and alternative EP additives evaluated in ISO 22 base oil. A combination of a commercially available, sulfur-containing additive package with a polymeric lubricity additive displays comparable performance to chlorinated paraffin. (Courtesy of Croda Inc.)

A commercially available sulfur-containing additive package was formulated into ISO 22 base oil, and the Reichert wear scars were measured using standard Reichert steel parts. Samples formulated with 10 percent chlorinated paraffin showed the expected low wear scar. The sulfur-containing additive package alone could not match this result. But when used in combination with a polymeric lubricity additive at 2-10 percent, wear scars are now comparable.

Hiroshi Sakata, manager polymer technical group for DIC in Chiba, Japan, focuses on two particular alternative EP additives. He says, “The typical alternatives to chlorinated paraffins are a sulfurized olefin that contains 40 percent sulfur, most of which is active and the combination of a sulfurized fatty oil mixed with overbased calcium sulfonates.”

There are several alternatives available to replace chlorinated paraffins in metalworking fluids, according to STLE member Victor Gober of The Elco Corp. in Cleveland. He says, “Some alternatives are nitrated vegetable oils, synthetic esters or combinations of sulfurized olefins and overbased calcium or sodium sulfonates.”

More specifically, several proprietary chlorine-free additives are available that will replace chlorinated paraffins in 80 to 85 percent of the applications. An example showing the effectiveness of alternative EP additives is found in Figure 4, which compares the performance of a chlorinated paraffin with a combination of a chlorine-free EP additive and a light-colored sulfurized additive. The Pin and Vee Block study shows that the mixture with the alternative EP additives displayed a lower torque, suggesting a reduced level of abrasive wear and a reduced presence of microwelds. High levels of both phenomena can lead to premature failure.


Figure 4. A mixture of a chlorine-free EP additive and a light-colored sulfurized additive exhibits lower torque than a chlorinated paraffin in a Pin and Vee Block study done in 150 N base oil. (Courtesy of The Elco Corp.)

STLE member Ben Faber, a metalworking fluid product manager for The Lubrizol Corp. in Wickliffe, Ohio, indicates that there are a number of chlorine-free options available to the metalworking fluid formulator. “Alternative chemistries include sulfurized fats and olefins, overbased sulfonates, polymeric esters and various phosphorus compounds,” Faber says.

STLE member Chad Crocker, metals technical manager for PCC-Chemax, Inc., in Piedmont, S.C., provides a similar list. He says, “Among the alternatives to chlorinated paraffins are high molecular weight/viscosity polymer esters, phosphate esters and sulfurized additives.”

According to STLE member Thomas Rossrucker, vice president-technology, Lubricant Division for Rhein Chemie Rheinau GmbH in Mannheim, Germany, the replacement of chlorinated paraffins is sometimes very challenging because this additive type is multifunctional and works under a wide spectrum of operating conditions. He says, “It is often not possible to substitute for chlorinated paraffins with just one additive type/group. Depending upon the application, synergistic combinations of various additives are used. In general, the lubricity part is covered by polymers, in particular sulfurized polymers and special polymer esters. The EP and antiwear function of chlorinated paraffins is not very distinct. Therefore, typical EP additives such as sulfurized olefins, triglycerides, fatty acids or esters and also thiadiazole derivatives can be used solely or in combination with esters, dispersants, overbased sulfonates or phosphorus-containing additives to cover the antiwelding and antiwear functionality.”

FLUID TYPES AND APPLICATIONS
Sakata believes sulfurized EP additives are used in most types of neat oils. “Active sulfurized olefins are typically used in cutting, forming or rolling oils,” he says. “Inactive sulfurized fats are used in cutting and press forming operations. Both of these types also can be blended for use in heavy duty cutting or forming.”

A new inactive sulfurized olefin containing 30 percent sulfur shows good performance in neat oil fluids compared to other sulfurized additives. Figure 5 shows 4-Ball EP test data (ASTM D2783) for the 30 percent inactive sulfurized olefin versus a 22 percent di-t-dodecyl polysulfide and a 40 percent active sulfurized olefin. The results indicate that the 30 percent inactive sulfurized olefin demonstrated the same performance as the di-t-dodecyl polysulfide at 1/5 of the treat rate. This inactive sulfurized olefin also displays almost the same performance as the 40 percent active sulfurized olefin.


Figure 5. Two 4-Ball EP studies show the capability of a 30 percent, inactive sulfurized olefin to display similar performance to di-t-dodecyl polysulfide at a much lower treat rate and to a 40 percent active sulfurized olefin. (Courtesy of DIC).

Sakata adds, “The 30 percent inactive sulfurized olefin also can be used in water-soluble applications because of its stability and EP performance.”

Faber believes that chlorinated paraffins can be replaced in nearly any metalworking application, including drawing, stamping, broaching and gun drilling using all types of metalworking fluids, including straight oils, soluble oils and semisynthetic fluids. He says, “In a recent case, we were able to replace a soluble oil stamping fluid containing a chlorinated paraffin with a ‘neo-synthetic’ metalworking fluid containing a water-dispersible polymeric ester. This fluid was used in a three-stage stamping operation to make high-strength steel tire plates for heavy equipment. This switch was especially important because these parts were to be welded later, and the OEM had restrictions on chlorine residues on the parts.”

Rossrucker states that chlorinated paraffins are not used in full synthetic fluids but, rather, in soluble oils and neat oils. He says, “For soluble oils typically used for applications such as drilling, milling, turning, etc., combinations of alternative EP and antiwear additives are commonly used to substitute for chlorinated paraffins. In neat oils, the alternative EP and antiwear additives have proven that they can replace chlorinated paraffins, even in severe applications such as cold forming, stamping, fine blanking, drilling, milling and turning of stainless steel and highly alloyed steel.”

Bonner contends that chlorinated paraffins in general will only be chosen in the most demanding applications and, therefore, are most likely to be found in neat oil formulations. The organic-based lubricity package and the polymeric lubricity additive can be used to replace chlorinated paraffins in neat oils or enable a formulator to switch to a semisynthetic or synthetic formulation with performance rivaling neat chlorinated paraffin-containing fluids. He says, “For example, the organic- based lubricity package successfully replaced a chlorinated paraffin in a camshaft plant in a tapping application and has had field trial success in internal broaching and on alloys such as Inconel.”

Gober indicates that the proprietary chlorine-free additives can be used in not only the conventional MWFs but also with vegetable oils and esters. “We have found that one of these additives can be used in environmentally sensitive applications such as chainsaw lubricants,” he says.

Anderson draws a distinction between how two of the alternative EP additives can be used to replace chlorinated paraffins. He says, “Phosphate esters can be used in both straight oils and water-based emulsion-containing fluids. Typically, they are used in heavy duty applications such as rolling, drawing and cutting. As phosphate esters are surface active, they also can form part of the emulsion package for a reduction in raw material cost.”

With sulfurized additives, Anderson also discusses the difference between using inactive and active sulfurized compounds. “Sulfurized molecules can be used in a similar manner to phosphate esters, although most of these are purely oil-soluble,” he says. “The higher activation temperature required for inactive sulfur means that these molecules are generally used for particularly difficult operations. Active sulfur is effective at lower loads but brings corrosion and staining issues with it that must be addressed by the formulator.”

BENEFITS OF ALTERNATIVE EP ADDITIVES
Crocker feels that the large variety of alternative EP additives gives the metalworking fluid formulator sufficient flexibility in preparing chlorine-free products. “The right combination of alternative EP additives can provide improved lubricity, leading to increased tool life,” he says.

STLE member Larisa Marmerstein of The Elco Corp. comments that higher disposal costs due to new regulatory restrictions increase the cost of working with chlorinated paraffins. She says, “The new, alternative EP additive chemistries have no regulatory restrictions, can be used at a third to a fifth the treat rate of chlorinated paraffins and still get equal or better performance in bench testing and real-world applications. These chemistries may cost more per pound than chlorinated paraffin, but it may be the same or less when the net treat cost is taken into account.”

Another consideration is the possibility for residual chlorinated paraffin left on metal parts to interfere with coating or cause corrosion. Marmerstein continues, “Chlorinated paraffins form a tenacious film that, if left on the parts, may interfere with coatings or cause steel corrosion. In contrast, amine-phosphite chemistries are easy to clean and may have additional corrosion inhibiting benefits.”

Anderson agrees about the possibility of residual chlorinated paraffin presenting corrosion issues and maintains that the main benefit of replacing chlorinated paraffins is environmental. He adds, “One other benefit of alternative EP additives is found in water-containing fluids where the intrinsic stability of phosphate esters and sulfurized additives is somewhat higher than chlorinated paraffins.”

Lubrizol’s Faber feels that switching away from chlorinated paraffins gives the formulator peace of mind. “The health, environmental and regulatory concerns that come with chlorinated paraffins can be avoided by removing them,” he says. “This gives a formulator assurance he or she will not be forced to follow the chlorinated paraffin debate in the industry or abide by any future regulations that may come at a later date. The uncertainty with chlorinated paraffins has made the term ‘chlorine-free’ a positive marketing claim in the industry.”

Bonner points out that use of alternative EP additives will be a more important factor due to the implementation of GHS at the end of May 2015. He says, “GHS is coming, and with more stringent labeling requirements the issues with some materials will be highlighted and more visible to workers. Formulators and end-users will be required to provide products that enable a safer working environment.”

Sakata says sulfurized additives can provide benefits from the standpoints of performance, formulation flexibility and odor. He says, “Sulfurized EP additives are designed to reduce the friction between metal surfaces by forming metal sulfide tribofilms at a wide range of temperatures. This benefits the metalworking fluid formulator by contributing better surface finish and extended tool life. The high sulfur content of some sulfurized additives provides the formulator with a high degree of flexibility in working with other components. Sulfurized EP additives are also available that exhibit low odor, which can contribute health and safety benefits to formulators and end-users.”

Rossrucker summarizes the benefits by saying, “Use of alternative EP additives will give metalworking fluid formulators wider market access by preparing fluids that have fewer health risks, corrosion risks and limitations due to specific country regulations. Other benefits include the possibility of higher machining speeds and the ability of formulators to develop more specific products to meet customer needs rather than just supplying duplicate fluids.”

REPLACEMENT OF CHLORINATED PARAFFINS
Formulators should follow five steps in replacing chlorinated paraffins with alternatives in a specific application. Faber says, “First, the formulator needs to find a lubrication test or tests that replicate the intended application. Second, the formulator should identify the most effective chlorinated paraffin replacement alternatives. This step includes evaluating synergistic combinations such as sulfurized olefins and overbased sulfonates. Step three is if the formulator is making a water-based fluid. In that case, he should confirm and adjust emulsifier performance as needed.”

When all this is accomplished, step four is to evaluate the formulations using bench top laboratory tests. The final step is confirming positive laboratory results through the use of in-house CNC testing or field trial testing that matches the intended application.”

Anderson recommends that formulators do careful testing both in the lab and in production facilities in the reformulation process. He says, “Because the performance profiles of chlorinated paraffins and the available alternatives are so different, it is hard to distinguish chlorinated paraffin replacement from the formulation of a completely new fluid for the same application.”

Gober indicates that the alternative EP additives are not direct “drop-in” replacements for chlorinated paraffin. He adds, “These alternatives are used at different percentages, have different structure, pH, polarity, etc. It is good to start reformulation with a confirmation of base oil solubility and emulsion stability for the water-based fluids. More work may need to be done for soluble oils, as the new chemistries might require use of different emulsifiers.”

Further assistance to formulators in determining the right chlorine-free alternative technology to use in specific applications can be obtained from additive suppliers, according to Rossrucker. “Some additive suppliers provide information on additive performance under specific conditions and in real field tests and will even recommend starting formulations,” he says. “It is not possible to substitute chlorinated paraffins just based on the chlorine content.”

EVALUATION
All of the respondents indicated that there are a number of lab tests that can be used to evaluate alternative EP additives. Examples include the Falex Pin and Vee Block, Falex Tapping Torque, 4-Ball, Microtap and the Twist Compression tests.

The advice from all of the respondents is to do initial screening tests followed by focusing on the specific application in the lab and/or in field trials.

SYNERGISM
Rossrucker offers some advice on how to find alternative EP additive combinations that will improve metalworking fluid performance. “There are many theories on synergistic performance of extreme pressure additives,” he says. “In many cases, the synergistic additive provides a function the extreme pressure additive is lacking. For example, a very polar unsaturated ester may provide the lubricity needed until the reaction temperature is reached to make the sulfur work. Other synergistic effects may be caused by real chemical reactions between the synergists.”

He continues, “EP additives are very versatile and multifunctional. Products based on special selected raw materials are available. Additives excellent for cutting fluids might not be suitable for heavy duty deformation and vice versa. Therefore, combinations of various additives working synergistically are used.”

As an example, Rossrucker recommends four additive types that can work synergistically with sulfurized additives:

• Polycarboxylates, Polymeric Esters
• Overbased Sulfonates
• Polyisobutenylsuccinic Anhydride (PIBSA) Derivatives
• Molybdenum Compounds.

Figure 6 shows an example of synergism found with sulfur and phosphorus EP additives in a study done to evaluate neat oils in a gear milling application on the steel alloy 42 CrMo4V (ASTM 4140). As the cutting speed increases, neat oils formulated with a sulfurized olefin/triglyceride or a combination of the sulfurized additive with a phosphorus/sulfur compound provide superior tool life as compared to chlorinated paraffin.


Figure 6. A blend of sulfurized olefin/triglyceride with a phosphorus/sulfur compound shows superior tool life as compared to chlorinated paraffin in a gear milling application. (Courtesy of Rhein Chemie Rheinau GmbH)

Sakata agrees that a synergism can be seen with sulfurized additives and overbased calcium sulfonates. He says, “Formulating with calcium sulfonate and sulfurized olefins or fats can produce a synergistic effect. Small calcium particles might help the reaction between the sulfurized EP additives and the metal surface.”

Bonner indicates that boundary lubricity additives can be used synergistically with alternative EP additives. He says, “Lubricity additives can be designed through techniques such as molecular design and surface imaging to work synergistically with non-chlorine-containing antiwear and EP additives.” An example was shown earlier in Figure 3.

Anderson agrees and says, “Combinations of overbased calcium sulfonates and active or inactive sulfurized molecules appear to be synergistic, as are sulfur and phosphorus in neat oil formulations. Combining these molecules with polymeric boundary lubricants can create substantial additional improvements in performance as well.”

Scott Prickett, a metalworking product manager for the Lubrizol Corp., says, “It is important to have the right blend of extreme pressure additives to cover the temperature ranges that may occur from 200-1,000 C (see Figure 1). This will provide additional performance to the fluid and allows it to be used in more applications. By using a mixture of polymeric esters, sulfur and phosphorus additives, the EP additives can activate across the entire temperature range and provide the performance needed for the machining or stamping operation. This combination yields better lubricity than if the fluid contains only one type of EP additive.”

FUTURE TRENDS
Insight was obtained from the additive suppliers about future trends for the use of EP additives. Bonner says, “Regulations will govern the usage or lack thereof for chlorinated paraffins. Due to economics, formulators will continue to utilize chlorinated paraffins until they are forced to switch. Now that materials are available on the market that can meet the EP performance levels of chlorinated paraffins, the move away from them can be accelerated.”

Bonner continues, “Beyond this, some formulators are also looking to reduce levels of non-chlorinated antiwear/ EP additives to move to a ‘hazardfree’ metalworking fluid. This futureproofs the formulation so that it will not need to be changed in the face of any further legislation on additives and labeling.”

Anderson is also in agreement that chlorinated paraffins won’t be abandoned by formulators until mandated by law. He says, “The cost effectiveness and functionality of chlorinated paraffins are very attractive and will drive their continued use where possible. Eventually, it is quite likely that chlorinated paraffins will be prohibited. With some commitment and enough time to formulate substitutions, very few machining applications will be unable to be replaced with alternative EP additives.”

Crocker stresses the growing use of phosphate esters to provide EP performance in the future. “We see phosphate esters/derivatives use growing as end-users turn to use more aluminum in the future because this metal exhibits light weight combined with excellent strength,” he says. “Besides providing EP characteristics, phosphate esters also impart the additional benefit of providing antistaining properties on aluminum alloys.”

Sakata believes that strict regulation of chlorinated paraffin use will expand globally, emphasizing the importance of finding alternative EP additives. He adds, “Currently, machined parts are becoming smaller and more complex physically. Metalworking operations on these parts will require higher lubricant performance because of the harsher conditions for lubrication (more force per area). We expect that formulators will rely more on EP additives (and other lubricant additives) to meet the enhanced level of lubrication required.”

Prickett predicts a growing need for EP additives due to the more severe machining conditions and the tighter tolerances for machined parts. “Manufacturers are anticipating higher production rates due to increased demand for their products in the upcoming years,” he says. “Despite this increase in demand, manufacturers most likely will not invest in new equipment—they will rely on their existing machinery to increase throughput. This means speeds and feeds will increase, and more operations will require extreme pressure lubrication. The need for improved metalworking fluid performance will be an expectation, not just a ‘nice to have’ characteristic of the fluid.”

Rossrucker sees the wider use for alternative EP additives in more highly refined base oils and also in water-based formulations. He says, “Improving solubility and odor of traditional sulfurized additives is a focus. Highly refined base oils (Group II and III) as well as synthetic base oils such as polyalphaolefins and GTL (gas-toliquid) require a modification of EP additives. Suitable replacements for traditional sulfurized fats are already available today.”

Rossrucker continues, “Future trends suggest that water soluble and emulsifiable products will replace neat oil formulations. This trend will continue not only for light to medium duty operations but also for severe machining processes.”

The use of EP additives in the future will include all of the major types described in this article. Synergisms among EP additives and with boundary lubricity additives provide the formulator with a number of different approaches that can be used to meet the growing number of metalworking applications.

At this point, chlorinated paraffins still appear to be an option for future formulators. The only question remaining is which types of chlorinated paraffins will be available.

Further information on EP additives can be found in a previous TLT article (4).

REFERENCES
1. Canter, N. (1997), “Additives for Metalworking Fluids,” in Booser, E., Tribology Data Handbook, CRC
Press, Boca Raton, Fla. and New York, N.Y., pp. 862-871.
2. Canter. N. (2009), “Special Report: Boundary Lubricity Additives,” TLT,” 65 (9), pp. 10-18.
3. Jaques, A. (2014), “Chlorinated Paraffins: Maintaining a Long-Term Focus in a Complex Regulatory Environment,” Compoundings, 64 (5), pp. 13-14.
4. Canter, N. (2007), “Special Report: Trends in extreme pressure additives,” TLT, 63 (9), pp. 10-18.

Neil Canter heads his own consulting company, Chemical Solutions, in Willow Grove, Pa. Ideas for Tech Beat items can be sent to him at neilcanter@comcast.net.