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504 Lubricant Additives: Chemistry and Applications
In the case of water base uids such as hydraulic, metalworking, water-glycols, antifreeze, and
other similar uids, the use of demulsi ers, emulsi ers, biocides, and corrosion prevention additives
are often required.
Metalworking uids can contain AW, EP, antimist, corrosion inhibitors, biocides, antifungi-
cides, defoamers, couplers, and dyes.
20.14 INDUSTRIAL APPLICATIONS
The preceding Section 20.13 has described the form and function of additives and the chemistry
involved in the use of these additives. The areas of industrial application are extremely diverse, both
in terms of applications and in the severity of the conditions under which the additives must perform
and maintain the integrity and quality of the lubricant.
Following is a list of some of the more important lubricants for industrial applications.
1. Air tool lubricants
2. Bearing lubricants
3. Cable oils
a. Hollow cables
b. Solid cables
4. Chain lubricants
5. Compressor lubricants
a. Air compressors
b. Reciprocating compressors
c. Rotary screw compressors
i. Oil- ooded compressors
d. Rotary vane compressors
e. Centrifugal compressors
f. Axial ow compressors
g. Gas compressors
i. Natural gas compressors
ii. Ethylene compressors
iii. Process gas compressors
h. Refrigeration compressors
i. Reciprocating compressors
ii. Rotary screw compressors
6. Condenser oils
7. Conveyor lubricants
8. Drilling uids
9. Gear lubricants
a. AW
b. EP
c. R&O
10. Grease
11. Heat transfer uids
12. Hydraulic oils
a. Gear pumps
b. High-pressure hydraulics
c. Piston pumps
d. Vane pumps
13. Metalworking uids
a. Continuous casting
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Additives for Industrial Lubricant Applications 505
b. Cold forging
c. Cutting
d. Coolants
e. Drawing
f. Extrusion
g. Grinding
h. Honing
i. Lapping
j. Punching
k. Rolling
l. Quenching
m. Spark erosion oils
14. Mold release agents
15. Rubber release agents
16. Shock absorber oils
17. Switch gear oils
18. Textile lubricants
19. Turbines
a. Gas turbines
i. Aircraft turbines
b. Steam turbines
20. Transformer uids
21. Vacuum pump oils
22. Vibration damping oils
23. Wire rope protection uids
Each of these applications has various subsets, and lubricants and the additives used will depend
on the properties of the oil and the performance requirements for that oil. Some of these applica-
tions require oil-only formulations and, therefore, require oil-soluble additives. Other formulations,
especially in some metalworking applications, use oil-in-water emulsions, and these formulations
require different additive chemistries. Details on the types of additives that are used in each of these
areas can be found in various chapters of this book and in several excellent references [2,3,66].
Essentially all industrial lubricants include some additives, even if only a protective amount
of antioxidant or a small amount of AW additive. Bench tests are typically used to screen the
performance of additives. This is done because the cost of testing using bench tests is signi cantly
less than the cost of eld test or full-scale equipment tests. An additional reason is that tests can
be performed using less lubricant, and test times permit more variations to be evaluated than can
typically be done in full-scale equipment.
There are countless methods available for evaluating lubricant formulations. These range from
measuring physical properties, for example, viscosity, pour point, ash point, re point, speci c
gravity, and volatility, to structural analysis using infrared spectroscopy, elemental analysis, aniline
point, and carbon residue. Further testing might include corrosion testing, hydrolytic stability, seal
compatibility, and seal swell tests. There are also a wide variety of mechanical test methods such
as the four-ball wear test and various Falex test methods. Most of the industry-accepted tests are
those listed by the Institute of Petroleum, the American Standard Testing Materials (ASTM), the
Deutsche Industrie Normung (DIN), the Japan Industrial Standard (JIS), and the Co- ordinating
European Council (CEC). A summary of many of these standard test methods can be found in
Chapter 27.
In addition to the standard test methods, there are several laboratory test techniques that have
been used to evaluate various aspects of lubricant uids and formulations. Furthermore, there are
many unpublished proprietary methods that have been designed and used by various companies in
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506 Lubricant Additives: Chemistry and Applications
the lubricant industry. A few examples of analytical techniques that have been applied to lubricant
evaluation will be described in the following few paragraphs.
Thermal methods, such as thermogravimetric analysis (TGA) and pressure differential scan-
ning calorimetry (PDSC), have been used to evaluate volatility, oxidation stability, and deposit-
forming tendencies [67–74]. Noel and Cranton were among the rst to realize the potential of using
DSC for characterizing lubricant uids [67–69].
A method has been developed using DSC to evaluate the remaining useful life of a lubricant.
This work showed that one could use the data from DSC to essentially predict when to change the
oil in turbine engines resulting in savings in the costs associated with equipment failure by not
changing the oil soon enough and the costs associated with changing the oil too soon because of
inaccurate data on the quality of the used oil [70].
In-Sik Rhee [71] has reported on the development of a new oxidation stability test method for
greases using a PDSC. Advantages to use of PDSC are that only small samples are required, the
analyses are rapid and repeatable, and sensitivity is high.
The observation that lubricant base uids exhibit differences in volatility depending on whether
air is present or not has been demonstrated, and this difference has been described as the oxida-
tion-mediated volatility [75]. Others have used DSC to evaluate the thermooxidative stability of
formulated lubricants using thermal analytical methods [76].
Standard oxidation tests are routinely used to determine the quality of a lubricant formulation,
and the results of these tests are frequently listed in the product speci cation or on the technical
data sheets for the product. Two important industry tests are the rotating pressure vessel oxidation
test (RPVOT), ASTM Method D2272, and the oxidation characteristics of inhibited mineral oils,
ASTM Method D943. Both of these are examples of bulk oxidation tests [77]. More recently devel-
oped oxidation tests are the thin- lm oxygen uptake test (TFOUT) and a thermooxidation engine
oil simulation test (TEOST). These, in contrast to the previously described tests, are thin- lm oxi-
dation tests [78,79]. All of these tests are used to evaluate the thermal and oxidative stability of base
uids and formulations containing additives expected to enhance performance.
Evaluation of friction and wear can be performed on various testers. ASLE (now STLE) in 1976
[80] compiled a list of 234 wear test methods. ASTM lists several friction and wear methods includ-
ing four four-ball methods—ASTM Methods D2266, D2783, D4172, and D51283 [76]. Variations of
the use of the four-ball test as a research tool are reported in the literature [81,82]. The Cameron-Plint
and pin-on-disc tests are also widely used for evaluation of materials, friction, and wear [83,84].
20.15 SUMMARY AND CONCLUSIONS
Additives perform a wide variety of functions and represent an important and necessary contribution
to the overall properties and performance of industrial lubricants. Without additives, even the best
base uids are de cient in some features. Formulation of a product is always a compromise. There is
always the issue of cost/performance. Many times, there is a great amount of research necessary to
balance the various effects of the different additives used in combination with the base oils.
The arsenal of lubricant additives is large, and yet, new additives continue to be developed.
This will help future lubricants meet the increasingly demanding conditions that equipment manu-
facturers require. Furthermore, environmental issues will require more benign and environmental-
friendly additive design in the future to meet the global regulations that are being proposed and
implemented.
ACKNOWLEDGMENT
I acknowledge J. M. Perez for his original chapter on additives for industrial applications in Lubri-
cant Additives: Chemistry and Applications, Marcel Dekker, New York, 1st Edition, 2003 from
which this chapter has been expanded, updated, and revised.
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Additives for Industrial Lubricant Applications 507
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E. R. Booser (Ed.), CRC Press, Boca Raton, FL, 1997.
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40. Liston, T. V., Lubricating additives—what they are and how do they function, Lubr. Eng. 48(5), 389–397,
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41. Spikes, H. A., Additive–additive and additive–surface interactions in lubricants, Lubr. Sci., 2(1), 4–23,
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process of zinc dialkyldithiophosphate, ASLE Trans., 16(3), 161–167, 1972.
43. Rounds, F. G., Some factors affecting the decomposition of three commercial zinc organic phosphates,
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46. Watkins, R. C., The antiwear mechanism of ZDDPs, Part II, Trib. Int., 15, 13–15, 1982.
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additives in white oil, ASLE Trans., 24, 77–90, 1981.
48. Perez, J. M., Ku, C. S., Pei, P., Hegeemann, B. E., and Hsu, S. M., Characterization of tricresylphophate
lubricating lms using micro-Fourier transform infrared spectroscopy, Trib. Trans., 33(1), 131–139,
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49. Taylor, L., Dratva, A., and Spikes, H. A., Friction and wear behaviour of zinc dialkyl-dithiophophate
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50. U.S. Patent 2,124,598 (Standard Oil—1938).
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56. Hamblin, P. C., Kristen, U., and Chasen, D., A review: Ashless antioxidants, copper deactivators and
corrosion inhibitors. Their use in lubricating oils, Int. Colloquium on Additives for Lubricants and
Operational Fluids, W. J. Bartz (Ed.), Techn. Akad. Esslingen, 1986.
57. O’Brien, J. A., Lubricating oil additives, in STLE Handbook of Lubrication, Vol. II, E. R. Booser (Ed.),
CRC Press, Boca Raton, FL, pp. 301–315, 1984.
58. Ibid., p. 309.
59. Haviland, M. L. and Goodwin, M. C., Fuel economy improvements with friction modi ed engine oils
in EPA and road tests, SAE Technical Paper No. 790945.
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61. Dancy, J. H., Marshall, H. T., and Oliver, C. R., Determining frictional characteristics of engine oils by
engine friction and viscosity measurements, SAE Technical Paper No. 800364, 1980.
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cants, ASLE Trans., 24, 232, 1981.
63. Klaus, E. E. and Tewksbury, E. J., Liquid lubricants, in STLE Handbook of Lubrication, Vol. II, E.R.
Booser (Ed.), CRC Press, Boca Raton, FL, pp. 229–253, 1984.
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Additives for Industrial Lubricant Applications 509
64. Peter Wu, C. S., Melodick, T., Lin, S. C., Duda, J. L., and Klaus, E. E., The viscous behavior of poly-
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Plenum Publishing Company, New York, p. 305, 1974.
70. Kauffman, R. E. and Rhine, W. E., Development of a remaining useful life of a lubricant evaluation
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71. Rhee I.-S., The development of a new oxidation stability test method for greases using a pressure dif-
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SAE Technical Paper No. 801383, 1980.
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831682, San Francisco, CA, SAE Special Technical Publication No. 558, 1983.
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microanalysis methods, SAE Technical Paper No. 910750, Detroit, MI, 1991.
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5(2), 133–148, 1988.
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of Lubricant Stability in ASTM Sequence IIIE, SAE Technical Paper No. 902121, Tulsa, OK, 1990.
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(TEOST), SAE Technical Paper No. 932837, 1993.
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511
21
Formulation Components for
Incidental Food-Contact
Lubricants
Saurabh Lawate
CONTENTS
21.1 Introduction ........................................................................................................................... 511
21.1.1 Background ..............................................................................................................511
21.1.2 Approval of Components and Base Oils .................................................................. 512
21.1.3 Registration of the Fully Formulated (Finished) Lubricant .................................... 513
21.1.4 Religious Approvals ................................................................................................. 513
21.1.5 Other Factors to Consider for Incidental Food-Contact Lubricants ........................ 514
21.1.6 Summary of Criteria for Incidental Food-Contact Lubricants ................................ 514
21.1.7 Components Used in Incidental Food-Contact Lubricants ...................................... 515
21.1.8 Base Oils for Incidental Food-Contact Lubricants .................................................. 515
21.2 Additives ............................................................................................................................... 515
21.2.1 Thickeners ............................................................................................................... 515
21.2.2 Tacki ers ................................................................................................................. 516
21.2.3 Pour Point Depressants ............................................................................................ 517
21.2.4 Antioxidants ............................................................................................................517
21.2.5 Antiwear and Extreme-Pressure Agents ................................................................. 519
21.2.6 Rust and Corrosion Inhibitors ................................................................................. 519
21.2.7 Defoamers ................................................................................................................520
21.2.8 Additive Packages for Incidental Food-Contact Lubricants ................................... 520
21.2.9 Formulation Challenges for Incidental Food-Contact Lubricants ..........................520
21.2.10 Future Outlook and Driving Forces for Components Used
in Incidental Food-Contact Lubricants .................................................................... 520
Ack nowledgment s ..........................................................................................................................522
References ...................................................................................................................................... 522
21.1 INTRODUCTION
21.1.1 B
ACKGROUND
Lubricants are used in the food industry during processing, production, manufacture, and packaging
of food products. Lubricating oils and greases as well as solid lubricants are used in the food industry.
These lubricants are classi ed into three categories—H1, H2, and direct food-contact lubricants.
A fourth category, H3, is generally applied to trolley lubricants. An excellent review of this topic is
found in the previous edition of this book [1,2].
By de nition, H1 lubricants have to be used in applications where the lubricant is likely to come
into contact with food, and as a result, H1 lubricants are called incidental food-contact lubricants.
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512 Lubricant Additives: Chemistry and Applications
These lubricants are also commonly referred to as food-grade lubricants in the industry, but this
term is to some extent misleading in that the end user may be led to believe that the lubricants meet
the same safety standards as edible food and food ingredients, which is not the case. In contrast, H2
lubricants can only be used in parts of a food plant where there can be no possibility of contact with
food. H1 lubricants can therefore be used in place of H2 lubricants but not the other way around.
The distinction between the categories is summarized in Table 21.1.
The nished lubricant and components undergo different levels of scrutiny.
21.1.2 APPROVAL OF COMPONENTS AND BASE OILS
The additive components and base oils used in the formulation of H1 lubricants must belong to
speci c sections in the Code of Federal Regulations, Book 21. These sections include [3]
Incidental Food-Contact Lubricants (21 CFR Section 178.3570)
Prior Sanctions List (21 CFR Section 181)
Generally Recognized as Safe (GRAS, 21 CFR Section 182)
Section 178.3570 speci cally contains ingredients that can be used as lubricating additives or base
oils for incidental food contact applications. To be listed in this section, the supplier has to petition
the Food and Drug Administration (FDA). This review could result in an opinion letter from the
FDA (which generally applies to chemical equivalents such as in cases where the sodium salt is
listed but the potassium salt is not) or a full review for new ingredients. A full review can be very
expensive and time-consuming. A key global supplier of incidental food-contact lubricants has
effectively developed, petitioned, and won approval for a large number of additives that are listed in
Section 178.3570 and has effectively enabled the development of this category of lubricants. On the
base oil side, there are many suppliers who have successfully passed the scrutiny of the FDA.
The prior sanctions list and GRAS list does not speci cally list ingredients for use in incidental
food-contact lubricants. However, if ingredients on these lists will function as additives, or base oils
they may be used in incidental food-contact lubricants. The prior sanctions list does not change as
it identi es components that have been grandfathered due to the history of safe use.
The GRAS list is a well-established list that contains numerous ingredients that are mostly of
value for food use, but there are some ingredients on the GRAS list that have lubricating properties.
For example, vegetable oils would t this category as they are on the GRAS list and can be used as
lubricant base oils. Likewise, lecithin and certain fatty acids are GRAS listed and may be used in
lubricants also. To list an ingredient as GRAS, the supplier can either self-af rm its GRAS status
or petition the FDA.
As noted later, the National Sanitation Foundation (NSF), Ann Arbor, Michigan, is the entity
that registers H1 lubricants [4]. All ingredients and base oils that belong to the 21CFR lists indicated
are now categorized as HX-1, whereas the nished lubricants are classi ed as H1.
•
•
•
TABLE 21.1
Classifi cation of Lubricants Used in the Food Industry
Lubricant Classifi cation Application Compliance
H1 Application where there is
possibility of food contact
21CFR Section 178.3570
H2 Application where there is no
possibility of food contact
Not de ned but generally the
lubricants must be free of any
toxic heavy metals or ingredients
H3 Trolley oils None de ned
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Formulation Components for Incidental Food-Contact Lubricants 513
21.1.3 REGISTRATION OF THE FULLY FORMULATED (FINISHED) LUBRICANT
Generally, lubricant suppliers to the food industry undertake the exercise of registering their
products as H1 or H2 lubricants. Until 2002, the U.S. Department of Agriculture (USDA) offered a
program to register H1 or H2 lubricants and granted letters of approval to the manufacturer of the
lubricant. The process involved submission of forms that outlined the complete composition (which
was held in con dence by the USDA) as well as a label and sample of the lubricant. The USDA
provided a letter of approval if the components of the lubricant complied with the 21 CFR sections
indicated earlier. The service was free. If there were one or more ingredients not belonging to the
sections mentioned earlier, then the USDA sought the opinion of the FDA.
However, the USDA abruptly discontinued this program in 1998. As a result, two organizations,
the NSF and the Underwriters Laboratory (UL), entered the fray with proposals to continue and
improve the program [1].
As of 2008, the NSF is now the key provider of this registration. More than 350 companies
worldwide have now registered their lubricants with the NSF, and the list continues to grow. Growing
awareness about the use of H1 lubricants is a key reason for this growth. Also, growth is driven by
the fact that the U.S. companies are opening manufacturing facilities in Asia, South America, and
other parts of the world. Previously, little consideration was given to the use of H1 lubricants in
these areas. But to stay competitive and to be able to export their food production, local companies
in these countries are also likely to use H1 lubricants, this is expected to spur further growth in
this market.
It must be noted that the NSF certi cation is not mandatory, and suppliers may self-certify their
products.
21.1.4 RELIGIOUS APPROVALS
In addition to approvals that are based on federal government criteria, there are certain approvals
associated with religious af liations that are sought after by manufacturers of components and
nished lubricants for incidental food contact.
The two key approvals are kosher and halal. Facilities that make food belonging to these
categories expect that the lubricants used in their facilities also meet this quali cation. As a
consequence, customers may demand kosher and halal certi cation for lubricants’ additives, and
nished lubricants.
For kosher and halal, manufacturers of additives base oils or nished lubes must generally meet
two distinct levels of compliance. The plant and process where the product is made must be kosher
or halal compliant, and the components or nished lubricant itself must be kosher or halal certi ed.
Often, therefore, the two criteria are not mutually exclusive but intertwined, and certi cation letters
may be obtained for the facility and the products.
Jewish dietary laws are termed kosher [5]. Although there may be slight differences in
interpretation of these laws by various kosher-certifying agencies, the ingredients and the facility
must meet the following criteria:
The products cannot mix meat and milk products or contain pork and related products. Also, if there is
an animal derived product then the animal must be slaughtered according to Kosher guidelines. From
a procedural standpoint no product should be processed on equipment that is processing non-Kosher
material. In such cases special cleaning and twenty-four hour wait periods apply.
In the United States, there are about 300 agencies that offer kosher certi cation. The Orthodox
Union in Manhattan, New York, is the largest and certi es about 4500 facilities in 68 countries. The
process involves a fee and a mandatory visit to the facilities by a rabbi. To maintain certi cation, a
company must be willing to pay the requisite fee and be amenable to unannounced inspections.
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