Learn what’s really involved in making a commercially viable product.
Despite conventional wisdom that oil and water don’t mix, water and oil can indeed seem to mix or at least form very stable emulsions, thanks to surfactants.1 There are all kinds of materials around us that derive some or all of their properties from the use of surfactants: engine oils, metalworking fluids (MWFs), certain other lubricants, a wide variety of face creams, lotions, conditioners and cosmetics, shaving cream, water-based paints and coatings, a wide variety of food products conjured by man and, in fact, almost anything that is a water-based non-solution.
That’s really only the tip of the iceberg in terms of what is really involved in making a commercially viable product. So perhaps it will be of use to peel back another layer of the onion to see just what the formulator is faced with when given the assignment to make a particular emulsified product. The formulator will need to apply a mix of science and art, whether the formulator works in the food, cosmetics, pesticides, MWFs or other industry.
First, remember the surfactant is a molecule that typically has a long carbon chain tail with some kind of polar head. The size and strength of the polar (hydrophilic or water-loving) head can vary as well as the size and strength of the hydrocarbon (lipophilic or water-hating) tail. To make matters worse, the nature of the polar head and hydrocarbon tail also can affect such properties of the final emulsion as:
- Toxicity
- Skin irritation
- Stability
- Resistance to salts
- Acids or alkalis
- Ease of manufacture
- Ease of dilution
- Storage stability
- Whether you get a water-in-oil or oil-in-water emulsion.
Added to that partial list, of course, is cost. Further, the material to be emulsified will have certain inherent properties that also will affect the decision on which emulsifier to use. Finally, most emulsified products will use more than one emulsifier. Thus, it is easy to see why there are so many commercially available emulsifiers on the market, even from a single company.
So what is the poor formulator to do? The first step is to define what the final product is supposed to do (what it is used for?) and what constitutes a satisfactory emulsion (what properties must the emulsion have?).
Additionally, such factors as those listed previously such as storage conditions, temperature in use, viscosity, whether you get oil-in-water or the opposite, etc., are not only listed but defined and specified.
Further, the methods for testing to determine whether those properties have been achieved and the necessary quality assurance requirements must all be defined and specified as well. Once this step is completed, many potential emulsifiers can be eliminated and certain chemical classes of emulsifiers will emerge as having the highest probability of success.
What’s the next step? Learn more about lubricant emulsifiers at STLE.org
This article is excerpted and reprinted with permission from the March 2016 issue of Tribology and Lubrication Technology (TLT), the official magazine of the Society of Tribologists and Lubrication Engineers, an international not-for-profit technical society headquartered in Park Ridge, Illinois. Read the full article at stle.org.
Reference:
- Tribology & Lubrication Technology: Want to mix oil and water?
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That’s interesting that metalworking fluids would contain an emulsification of oil and water. I have been considering getting some oil to use with my machines, but I could see how getting some with water in it could make it more cost-efficient. If that would work just as well as plain oil, I might have to consider getting some metalworking fluid like that.