The dilemma of promoting green products: what we know and don't know about biobased metalworking fluids.

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Introduction

For many decades, concerns have been growing about negative environmental, health, and safety impacts of chemicals and products that are derived from petroleum-based feedstocks. As a result, the search for environmentally friendly products, commonly referred to as "green products," has received worldwide attention in recent years. The U.S. and countries in Europe have continued to provide financial support toward research and development of "green products." In the U.S., many firms design and manufacture a myriad of biobased products and sell them as "green products" or "sustainable products."

Advocates of biobased products argue that these products are "green" because they are safer, more ecologically friendly, and healthier than their counterparts that are derived from petroleum feedstock (Honary, 2001). Little research, however, has focused on what actually constitutes "green products."

No universally agreed-upon criteria exist to define a "green product." It is generally construed as a product that will not damage environmental compartments such as air, water, or soils to a degree that will be socially, ecologically, and economically acceptable by society. In addition, "green products" will not affect consumers' or workers' health and safety. A study conducted recently used criteria such as global warming and ozone depletion potential, pH, flammability, and volatile organic compounds to evaluate biobased floor strippers for their ecological, health, and safety aspects (Massawe, Geiser, Ellenbecker, & Marshall, 2007). The weakness of these criteria is that they may apply only in limited circumstances, including geographical and political boundaries.

Biobased lubricants are a class of the so-called "green products" on the market today. They include metalworking fluids (MWFs), greases, hydraulic oils, and turbine oils. Manufacturers, formulators, and suppliers contend that biobased MWFs will soon replace the conventional petroleum-based MWFs as "green products." By the very nature of the functions of an MWF, however, biobased MWFs products must be formulated to meet the technical performance and other expectations of consumers in terms of efficiency and cost. As a result, petroleum-based MWF formulations use a series of additives to withstand robust work environments involving cooling of metal parts running against one another, usually in machine shops.

Recognizing that both conventional and biobased MWFs will require various additives to function well under various conditions, the goal of our study was to identify categories of these two MWFs and compare and contrast their health and safety aspects on the basis of their composition. In other words, our study was designed to investigate if the additives used in one type of MWF formulation varied significantly from the other and what this means in terms of their health and safety impacts.

Materials and Methods

Purpose

Our study was designed to investigate various categories of petroleum-based MWFs on the market and compare with biobased MWFs in terms of the composition or additives used in their formulations. To accomplish this objective, surveys and informal telephone interviews were administered to various formulators of biobased MWFs in the U.S. Relevant journals, books, trade magazines, and materials, particularly material safety data sheets (MSDS), were used as additional sources of information.

Surveys and Telephone Interviews

A questionnaire was designed and sent as a mail survey followed by formal and informal telephone interviews with the manufacturers and formulators of biobased MWFs in the U.S. Eleven manufacturers and one university research laboratory were contacted for this survey. This segment of stakeholders was considered a good source of primary information in our study. Only one perceived limitation of this method existed: a lack of cooperation due to the desire to protect market niche and trade secrecy, including pending patents.

The survey questionnaire focused on requesting generic information related to the MWFs and the additives that were being used to formulate biobased MWFs in particular. The main question asked was about the broad categories of additives used to make biobased MWFs, and the follow-up questions requested the specific types and amount of additives used in the biobased MWFs.

MSDS

To complement the above method, MSDS were obtained from the Internet and used to identify and quantify additives used to formulate biobased MWFs. Ideally, section 2 of any MSDS is generally supposed to be a public source of this category of information by providing the identity, amount, and possibly the toxic properties of chemicals. A Hazard Communication Standard (HCS) requires manufacturers and suppliers of chemicals to provide or make available to the public through MSDS any toxicity information for each chemical product stored, manufactured, or transported (Hazard

Communication, 2011). Employers and employees can rely upon this information to make informed decisions on the type of engineering controls or personal protective equipment or other preventive measures to use when they are handling a chemical or product containing toxic agents in the workplace and in the community setting. The strength of the MSDS in this regard is to provide information useful for evaluating health and safety aspects of various products. By using a chemical abstract service number, composition can be reported and subsequently determine a product's health and safety from other related toxicity databases.

Information Database

Literature review of peer-reviewed journals and other open-access publications was used to document various classes of petroleum-based MWFs and the properties of additives used in different classes of biobased MWFs. The Journal of Cleaner Production, Journal of Industrial Ecology, Industrial Lubrication and Tribology, Tribology International, and industry trade magazines such as Lubes 'n' Greases and the Agricultural-Based Industrial Lubricant magazine of the University of Northern Iowa were particularly useful for this purpose. In addition, proceedings from national and international conferences on tribology and product design were used. Electronic journal databases from various libraries were used to search for the availability of journals by using key words such as additives, biolubricants, life cycle assessment of biolubricants, and industrial ecology of the industrial lubricants.

Results and Discussion

Our study can report four classes of conventional petroleum-based MWFs as documented by the National Institute for Occupational Safety and Health (NIOSH, 1998). These MWFs are categorized as straight oils, soluble oils, synthetic, and semisynthetic. The four classes of petroleum-based MWFs reported by NIOSH are dependent upon the amount of the base oil or feedstock and the quantity of water used in each formulation (Gauthier, 2003; Whittaker, 1997). NIOSH has described the health and safety aspects of these petroleum based MWFs in detail (Whittaker, 1997).

Straight-Oil MWFs

Straight-oil MWFs, also referred to as "neat oil," are comprised of nearly 100% of base oils; this means that they are made up of severely refined mineral or petroleum products (Gauthier, 2003; Whittaker, 1997). In other scenarios, straight-oil MWFs have base oils derived from animals, marine life, or vegetables in combination with mineral oils (Gauthier, 2003; Whittaker, 1997). As expected, straight-oil-based MWFs are designed to improve the metalwork as a coolant but at the same time to prevent rusting of metal parts during operations, particularly in moderate- to heavy-duty machining work environments. It is reported that since the amount of petroleum feedstock used to formulate this category of MWFs is close to 100%, very few additives, and only in small quantities, are usually added to this category of MWFs (Childers, 1994).

Soluble-Oil MWFs

Soluble-oil MWFs are defined as emulsion fluids containing much less severely refined petroleum or vegetable oils than straight oil. The composition of severely refined petroleum or vegetable oils lies between 30% and 85% of petroleum-based feedstocks. The remaining components required to formulate these products are emulsifiers, pH stabilizers, rust preservatives, antifoaming agents, corrosion inhibitors, lubricity aids, viscosity modifiers, biocides, and extreme pressure additives such as chlorine, sulfur, and phosphorus-based additives.

Soluble oil-based MWFs are often diluted with water in the range of 5%-25%, creating the need to use biocides and emulsifiers as a way to limit environmental conditions conducive for bacteria or fungal growth (Hewstone, 1994; John, Bhattacharya, & Raynor, 2004).

Soluble oil-based MWFs were developed between 1910 and 1920 to replace strait-oil MWFs because the latter had many risks, including high flammability and poor cooling properties (Wu & Dacre, 1997). Due to the nature of the components used in this category of MWFs, technical performance characteristics of most soluble-oil MWFs are reported to be "extraordinarily good" when used in a high-temperature environment.

Synthetic Oil-Based MWFs

The third category of petroleum-based MWFs falls under the category of the synthetic oil-based MWFs that evolved in the 1950s as the concentrates of synthetic esters and organic and inorganic salts (Nachtman & Kalpakjian, 1985). Several additives are reported under this category of MWFs: synthesized hydrocarbons, polyglycols and phosphate esters, corrosion inhibitors, and biocides; and emulsifiers, chelating, anti-wear, wetting and coupling agents, rust preservatives, corrosion inhibitors, extreme pressure, antifoaming agents, surfactants, and dyes are often added in the formulation of these products (Fritz, 2006).

Semisynthetic-Based MWFs

The fourth category of petroleum-based MWFs is semisynthetic oil-based MWFs, commonly referred to as "preformed" emulsions (Choi, Ahn, Kwon, & Chun, 1997). These MWFs contain water in the range of 30%-40% and severely refined petroleum oils almost in the same percentage range (Ratoi, Anghel, Bovington, & Spikes, 2000). Additives reported for these products are emulsifiers, coupling agents, extreme pressure and antiwear agents, antifoaming and defoaming compounds, rust preservatives, and corrosion inhibitors.

Analyzing the additives presented above for petroleum-based MWFs categories echoes the sentiments that they seem to be a huge "library of cookbooks" or "a black box of chemical blends (Wu & Dacre, 1997)." This observation is also supported by the NIOSH findings of the additives used in the petroleum-based MWFs as evident in Table 1 (Bartz, 1998).

From the literature review, we recognized that a large and complex nature of additives is available for use with MWFs and other lubricant formulations on the market (Figure 1). The U.S. market for these additives for this purpose alone is about 33% of the total world demand or approximately 1.1 million tons (Modern Applications News, 2001). The market value of additives to support these traditional MWF formulations and other industrial lubricants worldwide is about $7.5 million (Lin & So, 2004).

Results of survey and telephone conversations with stakeholders in the industry inquiring about biobased MWFs indicate that three main classes of biobased MWFs are identified (Table 2) as opposed to the four classes of conventional MWF products that are identified and reported in literature through NIOSH documents. It can be reported that Table 2 shows a high resemblance to Table 1 for various types of additives commonly found in the conventional or petroleum-based MWFs as reported in NIOSH studies.

Out of 10 manufacturers or formulators who were contacted for this study, four (40%) responded to the question about the identity of the additives that were used in their biobased MWFs formulations. For example, one manufacturer noted that "we don't use sulfur, chlorine, or phosphate-based additives, but other manufacturers in the biobased industry do." Another biobased MWFs formulator expressed similar concerns over the products they formulated. He noted that biobased feedstocks form a large percentage of the company's biobased MWFs, however, they include other additives in the formulations in the form of "oilness additives" in order to control wetting, emulsification, and other properties that include colloidal stability of the final biobased MWFs. These two statements point out the possible use of additives that are also commonly or similarly used in the conventional petroleum-based MWFs.

As expected, none of the manufacturers or formulators of biobased MWFs disclosed information related to the identity or amount of the specific additives used to formulate their biobased MWFs. This outcome can only be perceived as an attempt to control market niche by protecting trade secrets and other related technical information.

MSDS and Information on Additives Found in the Biobased MWFs

Eleven MSDS were downloaded from the Internet and analyzed. As expected, most MSDS did not provide valuable information about the specific types and amounts of additives used to formulate biobased MWFs. Three out of 11 MSDS revealed the three categories of biobased MWFs as straight-oil, water-soluble, or semisynthetic-based MWFs.

Although one could tell from the MSDS that biobased MWFs formulations contained soybean oil as the main feedstock, other additives were not disclosed. A possible explanation for this could be the reluctance to reveal trade secrets and protection of pending patents. Nondisclosure of information can be crucial in evaluating the health and safety aspects of products and a comparative assessment can be relatively difficult to conduct in this situation. It is reasonable to assume that manufacturers are weighing the benefits of selling their biobased MWFs in a competitive market versus the burden of disclosing trade secret information through publicly available MSDS (Norrby, 2003). As expected, an HCS, which mandates disclosure of information on chemicals, has not been successful in this regard.

Regarding information disclosure on MSDS, Section 1910.1200(g)(2)(i)(c)(1) of HCS states the following: " ... the chemical and common name(s) of all ingredients which have been determined to be health hazards, and which comprise 1% or greater of the composition, except that chemicals identified as carcinogens under paragraph (d) of this section shall be listed if the concentrations are 0.1% or greater"; and Section 1910.1200(g)(2)(i)(c)(2) of this HCS law adds, "the chemical and common name(s) of all ingredients which have been determined to be health hazards, and which comprise less than 1% (0.1% for carcinogens) of the mixture, if there is evidence that the ingredient(s) could be released from the mixture in concentrations which would exceed an established OSHA permissible exposure limit or ACGIH Threshold Limit Value, or could present a health risk to employees (Hazard Communication, 2011)."

Table 3 provides only scanty information about biobased MWFs and the additives. This information may not be useful to make informed decisions about the extent of "greenness" of biobased MWF formulations. The language in the HCS is clear about the content of MSDS. We can only speculate that perhaps the disclosure of trade secrets is the main reason why manufacturers of biobased MWFs, who claim to be promoting these formulations as "green products," would not want to disclose information related to the individual components used to formulate such biobased products.

The only useful information appearing to promote biobased MWFs is presented in Table 2 showing that the feedstock (base oil) used in these products is within 5%-90%. Biobased feedstock, such as high oleic rapeseed, is derived from sunflower oils, soybean, or canolas, or the lard, neatsfoot, and tallow oils (Durak, 2004). While Table 3 illustrates the world production of biobased feedstocks and their corresponding fatty acids, Table 4 is an illustration of comparative performance of different base oils or feedstocks used to formulate MWFs.

Conclusion and Recommendations

Our study confirms that as many additives are used in the biobased MWF formulations as in the traditional or conventional petroleum-based MWF formulations. Some additives, such as biocides, can potentially be toxic, ecologically damaging, and probably unsafe. Our study did not address this issue in detail. With the information available now, it is difficult to conclude if biobased MWFs can be promoted as substitutes to petroleum MWFs in order to protect workers' health and safety or contribute to sustainability, as widely perceived.

Looking at the results of our study, it is relatively difficult to accept biobased MWFs as "green products" without subjecting them to a rigorous process of assessment on the basis of health and safety criteria regardless whether the feedstock used are biobased, which can be biodegradable. Perhaps biodegradability should not be the only deciding factor to categorize biobased MWFs as "green products" until a thorough knowledge of the health and safety information of individual additives is presented (Table 5). Until then, precautionary measures should be taken when promoting biobased MWFs as "green products" to avoid health and safety impacts of these products that could be similar to those presented by petroleum-based MWFs.

Research efforts should focus on identifying the specific types and amount of individual additives that manufacturers use to formulate various biobased MWFs. Regardless of the source, base oils should also be considered as a source of serious health concerns because of the potential of these feedstocks to aerosolize. To avoid this scenario, good housekeeping measures recommended for handling petroleum-based MWFs should also be planned and adopted to control worker and public exposures from aerosols related to working with biobased MWFs.

Another conclusion of our study is that it is difficult to depend on the information from manufacturers of biobased products, MSDS, and other literature sources about the specific types, the amount, and quantity of individual additives used to formulate biobased MWF products. This was anticipated because of the existing trade secret and potential pending patent information. MSDS that were used in our study did not reveal sufficient information to identify and quantify each additive used to formulate the biobased MWF products. It is true to state that information disclosure laws in the U.S. are flawed and they should be reviewed to support sustainable development of the biobased industry. One way is to hold manufacturers liable who cannot provide consumers with the information to make informed decisions about the "greenness" of biobased MWFs. Concurrently, a more transparent approval process for approving additives manufactured or used to formulate biobased MWFs and other related biobased products is needed. A process by the Food and Drug Administration designed to approve additives for the food industry can be adopted for the biobased industry.

Acknowledgements: The authors wish to acknowledge the assistance of Lowell Center for Sustainable Production and the Toxics

Reduction Institute, both at the University of Massachusetts Lowell, for supporting this research. Any views presented in this report are solely those of the authors and do not reflect the official position of these two institutions.

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Ephraim Massawe, ScD

Kenneth Geiser, PhD

Corresponding Author: Ephraim Massawe, Assistant Professor, Industrial Hygiene and Environmental Health, Southeastern Louisiana University, SLU 10847, Hammond, LA 70402. E-mail: [e-mail].

TABLE 1
Common Additives in Different Classes of Petroleum-Based
Metalworking Fluids

                                              Classification

Component            Function                 Straight Oils

Water                As a coolant, solvent,   Dissolved 10-500 ppm (a)
                     diluents

Mineral oils         Carries lubricants       60%-100%

Emulsifier           Emulsifiers              n/a

Chelating agents     Ties up ions in          n/a
                     solutions

Coupling agents      Stabilizes               n/a

VI modifiers         Maintains viscosity      Different amounts

Detergents           Prevents deposit         Different amounts
                     formation

Plasticizers         Reduces tackiness        n/a

Antimist agents      Reduces misting          Different amounts

Antiweld agents      Prevents welding         0%-20%

Oiliness agents      Increases film           Different amounts
                     strength

Surfactant wetting   Reduces surface          0%-10%
agent                tension

Dispersant           Prevents deposit         Different amounts
                     formation

Passivator           Prevents staining        Different amounts

Antifoaming          Prevents foaming         0-500 ppm
agents

Alkaline reserve     Acts as buffer control   n/a

Dyes                 Leak detection           n/a

Odorant              Masks odor               Different amounts

Corrosion            Prevents rust and film   0%-10%
inhibitors,          barrier
antirusts

Biocides             Prevents bacteria/       n/a
                     fungal growth

Extreme pressure     Reaction lubrication     0%-40%
additives

                     Classification

Component            Soluble Oils         Semisynthetic

Water                5-40 parts/1 part    10-40 parts/1 part

Mineral oils         30%-85%              5%-30%

Emulsifier           5%-20%               5%-10%

Chelating agents     0%-1%                0%-1%

Coupling agents      1%-3%                1%-3%

VI modifiers         n/a                  n/a

Detergents           Different amounts    Different amounts

Plasticizers         Different amounts    Different amounts

Antimist agents      Different amounts    n/a

Antiweld agents      0%-20%               0%-10%

Oiliness agents      n/a                  n/a

Surfactant wetting   5%-20%               10%-20%
agent

Dispersant           n/a                  n/a

Passivator           n/a                  n/a

Antifoaming          0-500 ppm            0-500 ppm
agents

Alkaline reserve     2%-5%                2%-5%

Dyes                 0-500 ppm            0-500 ppm

Odorant              Different amounts    Different amounts

Corrosion            3%-10%               10%-20%
inhibitors,
antirusts

Biocides             0%-2%                0%-2%

Extreme pressure     0%-20%               0%-10%
additives

                     Classification

Component            Synthetic

Water                10-40 parts/1 part

Mineral oils         n/a

Emulsifier           5%-10%

Chelating agents     0%-1%

Coupling agents      1%-3%

VI modifiers         n/a

Detergents           Different amounts

Plasticizers         Different amounts

Antimist agents      n/a

Antiweld agents      0%-10%

Oiliness agents      n/a

Surfactant wetting   10%-20%
agent

Dispersant           n/a

Passivator           n/a

Antifoaming          0-500 ppm
agents

Alkaline reserve     2%-5%

Dyes                 0-500 ppm

Odorant              Different amounts

Corrosion            10%-20%
inhibitors,
antirusts

Biocides             0%-2%

Extreme pressure     0%-10%
additives

Source: Bartz, 1998.

(a) ppm = parts per million.

TABLE 2
Additives in Three Classes of Biobased MWF Products Investigated

Component               Function               Classification

                                               Straight Oils

Water                   As a coolant,          --
                        solvent, diluents

Vegetable oils          Base oil               70%-100%

Emulsifier              Emulsifiers            n/a
(ester of
vegetable oil)

Chelating agents        Tie up ions in         n/a
                        solutions

Coupling agents         Corrosion/emulsion     n/a
TEA/MEA/DEA

Viscosity index         Maintain viscosity     Present in different
modifiers (blown                               amounts
vegetable oil)

Detergents              Prevents deposit       n/a
(alcohol ethoxy         formation
sulphate)

Antimist agents         Reduce misting         Present in different
                                               amounts

Extreme pressure        Prevent wear           0%-20%
and antiwear
(ZDDP)--phosphate
esters

Surfactant wetting      Reduces surface        0%-10%
agent                   tension
(polyisobutylene
succinic anhydride
amino ester)

Passivator              Prevents staining      Present in different
                                               amounts

Antifoaming agents      Prevent foaming        0%-1%
(polydimethylsiloxne)

Alkaline reserve        Buffer control         n/a
agents

Dyes                    Color                  n/a
(optional)

Odorant (optional)      Masks odor             Present in different
                                               amounts

Corrosion               Prevent rust           0%-10%
inhibitors,
antirusts

Biocides/               Fungal/bacteria        n/a
preservative            growth

Antioxidants            Prevent oxidation      0-1000 ppm (a)

Component               Classification

                        Water-Soluble Oils     Semisynthetic

Water                   5-40 parts/1 part      10-40 parts/1 part

Vegetable oils          30%-85%                5%-30%

Emulsifier              5%-20%                 5%-20%
(ester of
vegetable oil)

Chelating agents        0%-1%                  0%-1%

Coupling agents         1%-3%                  1%-3%
TEA/MEA/DEA

Viscosity index         n/a                    n/a
modifiers (blown
vegetable oil)

Detergents              Present in different   Present in different
(alcohol ethoxy         amounts                amounts
sulphate)

Antimist agents         Present in different   Present in different
                        amounts                amounts

Extreme pressure        0%-20%                 0%-20%
and antiwear
(ZDDP)--phosphate
esters

Surfactant wetting      5%-20%                 10%-20%
agent
(polyisobutylene
succinic anhydride
amino ester)

Passivator              n/a                    n/a

Antifoaming agents      0%-1%                  0%-1%
(polydimethylsiloxne)

Alkaline reserve        2%-10%                 2%-10%
agents

Dyes                    0-500 ppm              0-500 ppm
(optional)

Odorant (optional)      Present in different   Present in different
                        amounts                amounts

Corrosion               3%-10%                 10%-20%
inhibitors,
antirusts

Biocides/               0%-2%                  0%-2%
preservative

Antioxidants            n/a                    n/a

(a) ppm = parts per million.

TABLE 3
Biobased Feedstock: World Production and Type of Fatty Acid

                   World Production
Source            (Million Tons/Year)      Fatty Acid Type

Soybean oil               20                Linoleic oleic
Groundnut oil              4                Linoleic oleic
Palm oil                  16                Palmitic oleic
Rapeseed                 11.5                   Oleic
Sunflower                  9                Linoleic oleic
Beef tallow               7.5           Oleic palmitic stearic
Lard                       6                Oleic palmitic
Coconut oil                3                    Lauric
Palm kernel oil            2                    Lauric
Olive oil                  2                    Oleic
Fish oil                  1.5           Long chain fatty acids
Corn oil                  1.8               Linoleic oleic
Castor oil                0.5                 Ricinoleic
Linseed oil               0.6                  Linoleic

                  Carbon Chain Length and
Source             Number of Double Bonds

Soybean oil            C18:2 or C18:1
Groundnut oil          C18:2 or C18:1
Palm oil               C16:0 or C18:1
Rapeseed                   C18:1
Sunflower              C18:2 or C18:1
Beef tallow       C18:1 or C16:0 or C18:0
Lard                   C18:1 or C16:0
Coconut oil                C12:0
Palm kernel oil            C12:0
Olive oil                  C18:1
Fish oil          C20:2 to 6 or C22:2 to 6
Corn oil               C18:2 or C18:1
Castor oil               C18:1 -OH
Linseed oil                C18:3

Source: Igartua, 1999.

TABLE 4
Relative Comparison and Rating of Different Base oils

Characteristic                          Mineral       Polyalpha
                                          Oils         Olefines

Viscosity temperature behavior (VI)      4 (a)            2
Low temperature behavior                   5              1
(pour point)
Liquid range                               4              2
Oxidation stability (aging)                4              2
Thermal stability                          4              4
Evaporation loss, volatility               4              2
Fire resistance, flash temperature         5              5
Hydrolytic stability                       1              1
Corrosion protection properties            1              1
Seal material compatibility                3              2
Paint and lacquer compatibility            1              1
Miscibility with mineral oil               --             1
Solubility of additives                    1              2
Lubricating properties, load               3              3
carrying capacity
Toxicity                                   3              1
Biodegradability                           4             3/4
Price relation against mineral oils        --            3-5

Characteristic                        Polyalkylene   Dicarboxylic
                                        Glycols      Acid Esters

Viscosity temperature behavior (VI)        2              2
Low temperature behavior                   3              1
(pour point)
Liquid range                               3              2
Oxidation stability (aging)                3             2/3
Thermal stability                          3              3
Evaporation loss, volatility               3              1
Fire resistance, flash temperature         4              4
Hydrolytic stability                       3              4
Corrosion protection properties            3              4
Seal material compatibility                3              4
Paint and lacquer compatibility            3              4
Miscibility with mineral oil               5              2
Solubility of additives                    4              2
Lubricating properties, load               2              2
carrying capacity
Toxicity                                   3              3
Biodegradability                          1/2            1/2
Price relation against mineral oils       6-10           4-10

Characteristic                         Neopentyl       Rapeseed
                                       Polyesters        Oils

Viscosity temperature behavior (VI)        2              2
Low temperature behavior                   2              3
(pour point)
Liquid range                               2              3
Oxidation stability (aging)                2              5
Thermal stability                          2              4
Evaporation loss, volatility               1              3
Fire resistance, flash temperature         4              5
Hydrolytic stability                       4              5
Corrosion protection properties            4              1
Seal material compatibility                4              4
Paint and lacquer compatibility            4              4
Miscibility with mineral oil               2              1
Solubility of additives                    2              3
Lubricating properties, load               2              1
carrying capacity
Toxicity                                   3              1
Biodegradability                          1/2             1
Price relation against mineral oils       4-10           2-3

Source: Lin & So, 2004.

(a) Evaluation criteria: 1 = excellent;
2 = very good; 3 = good; 4 = moderate; 5 = poor.

TABLE 5
Specific Additives in the Biobased Metalworking
Fluids Based on Literature Review and Interviews

Specific Additive                     Functions                CAS #

Zinc dialkyl-                 Extreme pressure/antiwear     68649-42-3
dithiophosphate (ZDDP)

Chlorinated paraffin,         Extreme pressure/antiwear         n/a
sulfur, phosphorous

Alkyl hydrogen phosphites     Extreme pressure/antiwear         n/a

S-alkyl O,O dialkyl           Extreme pressure/antiwear         n/a
phosphorodithioate

Chlorinated paraffins         Extreme pressure/antiwear     108171-26-2

Tricresyl-phosphate (TCP)              Antiwear               78-30-8

Dibutyl 3,5-di-t-butyl 4               Antiwear                 n/a
hydroxy benzyl phosphate
(DBP)

Tri-n-octyl thiophosphate              Antiwear                 n/a
(TOTP)

Tri-n-octyl                            Antiwear                 n/a
tetrathiophosphate (TOTTP)

Antimony dithiocarbamates              Antiwear                 n/a

Molybdenum                             Antiwear                 n/a
phosphorodithioate

T-butyl phthalonitrile                 Antiwear                 n/a

Zinc                                   Antiwear                 n/a
dialkyldithiocarbamate

N-phenyl-1-naphthylamine             Antioxidant              90-30-2

Dicarboxylic acid esters      Viscosity index modifiers         n/a

Lubrizol[R]7653               Viscosity index modifiers         n/a

-butylated phenol                                               n/a
(10%-19.9%)

-substituted triazole                                           n/a
(0.5%-1.5%)

-diphenylamine (0.1%-0.9%)                                   122-39-4

Diamond-like coatings             Thermal protection            n/a
(DLC)

Calcium alkaryl                       Detergent                 n/a
sulphonates

Calcium sulfonate                Corrosion resistance       61789-86-4

Sodium sulfonate                                             61789853

Triethanolamine (TEA)        pH Stabilizers; surfactants;    102-71-6
                             corrosion or rust inhibitors
Diethanolamine (DEA)                                         111-42-2

Monoethanolamine (MEA)                                       141-43-5

Diglycoamine (DGA) or                                        929-06-6
2-(2-Aminoethoxy)ethanol

Diphenylamine                        Antioxidant                n/a

Phenol                               Antioxidant                n/a

4,4'-dioctyldiphenylamine            Antioxidant                --
(DAT)

N-phenyl-1-naphthylamine             Antioxidant                --
(PAN)

Triazine                               Biocides              4719-04-4

1,3,5-Triazine-1,3-5 (2H,                                    7632-00-0
4H, 6H)-Triethanol (9CT)
and S-Triazine-1,3,5 (2H,
4H, 6H)-Triethanol (8CI)

Carbamic acid, butyl-,                                      55406-53-6
3-iodo-2-propynyl ester
(IPBC)

Hexahydro 1,3,5, tris (2-                                    4719-04-4
hydroxyethyl)-s-triazine

Hexahydro 1,3,5, tris                                         136356
ethyl-s-triazine

Hexahydro 1,3,5 tris (2                                         n/a
hydroxyproyl)-s-triazine

Dimethoxane                                                  828-00-2

Methylene-bis-oxazine                                           --
(4,4'-
methylenedimorpholine)

Polyisobutylylene                      Antimist                 n/a

Amine borate                      Alkaline reserves          63231481

1,2,4-Triazole                        Detergent              288-88-0

Sodium laureth sulfate or             Passivator             9004-82-4
sodium lauryl sulfate
ethoxylate

NaN[O.sub.2]                     Corrosion inhibitors        7632-00-0

KN[O.sub.2]                                                  7758-09-0

Specific Additive            References

Zinc dialkyl-                Barnes, Bartle, & Thibon, 2001; Nicholls
dithiophosphate (ZDDP)       et al., 2005; Snyder & Foster, 1983; Wu
                             & Dacre, 1997

Chlorinated paraffin,        Childers, 1994; Pawlack, 2003
sulfur, phosphorous

Alkyl hydrogen phosphites    Bansal, Dohhen, & Sarin, 2002

S-alkyl O,O dialkyl
phosphorodithioate

Chlorinated paraffins

Tricresyl-phosphate (TCP)    Choi et al., 1997

Dibutyl 3,5-di-t-butyl 4     Choi et al., 1997
hydroxy benzyl phosphate
(DBP)

Tri-n-octyl thiophosphate    Weimin et al., 2004
(TOTP)

Tri-n-octyl
tetrathiophosphate (TOTTP)

Antimony dithiocarbamates

Molybdenum
phosphorodithioate

T-butyl phthalonitrile       Yavrouian, Repar, Moran, Lawton,

Zinc                         & Anderson, 1994
dialkyldithiocarbamate

N-phenyl-1-naphthylamine

Dicarboxylic acid esters     Kenar et al., 2005

Lubrizol[R]7653              Zhang et al., 2002

-butylated phenol
(10%-19.9%)

-substituted triazole
(0.5%-1.5%)

-diphenylamine (0.1%-0.9%)

Diamond-like coatings        Kalin & Vizintin, 2005
(DLC)

Calcium alkaryl              Bartz, 1998; Boris & Vizintin, 2003;
sulphonates                  Kalin & Vizintin, 2005

Calcium sulfonate            Miller, 2009

Sodium sulfonate

Triethanolamine (TEA)

Diethanolamine (DEA)

Monoethanolamine (MEA)

Diglycoamine (DGA) or
2-(2-Aminoethoxy)ethanol

Diphenylamine

Phenol

4,4'-dioctyldiphenylamine    Bakunjin, Kuzmina, & Parenago, 2000
(DAT)

N-phenyl-1-naphthylamine
(PAN)

Triazine                     Miller, 2009; Sollenberg & Stahlbom, 1999

1,3,5-Triazine-1,3-5 (2H,
4H, 6H)-Triethanol (9CT)
and S-Triazine-1,3,5 (2H,
4H, 6H)-Triethanol (8CI)

Carbamic acid, butyl-,
3-iodo-2-propynyl ester
(IPBC)

Hexahydro 1,3,5, tris (2-
hydroxyethyl)-s-triazine

Hexahydro 1,3,5, tris
ethyl-s-triazine

Hexahydro 1,3,5 tris (2
hydroxyproyl)-s-triazine

Dimethoxane

Methylene-bis-oxazine
(4,4'-
methylenedimorpholine)

Polyisobutylylene

Amine borate

1,2,4-Triazole

Sodium laureth sulfate or
sodium lauryl sulfate
ethoxylate

NaN[O.sub.2]

KN[O.sub.2]

FIGURE 1

Demand for Additives (Tons) in the Industrial
Lubricants Industry by Continent

Europe            1065; 31%
America           1100; 33%
Pacific            475; 14%
Asia               650; 19%
Africa               90; 3%

Source: Rajewski, Fokens, & Watson, 2000.

Note: Table made from pie chart.