a time-saving guide to emulsifier selection
edited and reprinted from CHEMMUNIQUE, publication of ICI Americas Inc.
ICI Americas Inc.
Wilmington, Delaware 19897
HLB scale of typical ATLAS emulsifiers
TWEEN 40 TWEEN 80 TWEEN 60
TWEEN85 TWEEN 65
TWEEN 81 TWEEN 61
Meaning of HLB Advantages and Limitations
SPAN 60 SPAN80
SPAN 65 SPAN 85
Trademarks of ICI Americas Inc., include:
ARLACEL, ARLASOLVE, ARLATONE, ATLAS, ATLOX, ATMOS, ATMUL, BRIJ, MYRJ, RENEX, SPAN, TWEEN, TWEEN-MOS
© 1976 ICI Americas Inc. (All Rights Reserved) Revised, March, 1980
WHEN you are faced with the problem of making an emulsion, youhave your choice of hundreds upon hundreds of emulsifying agents - well over a hundred just from ICI alone. Out of this welter of products, you have the unenviable task of selecting one or two which will satisfactorily emulsify your chosen ingredients. You can choose from among hundreds of manufacturers and thousands of surface active agents, according to the 1975 edition of John W. McCutcheon's"Detergents and Emulsifiers" Your own definition of the words "satisfactorily emulsify," as used above, is of course the prime factor in your choice of one emulsifier instead of another.
-or non-irritating to the skin? How about your manufacturing equipment -or the equipment your customer might use in applying your emulsion product-will ease of preparation or application affect your choice ofemulsifier? Such factors as this may immediately lead you to discard certain types or groups of emulsifiers from further consideration. In any case, they will certainly influence your choice of emulsifiers when you are weighing the relative merits of one emulsion or another in final trials.
HLB Numbers of Emulsifiers What Do They Mean? In the HLB System, each emulsifier is assigned a numericalvalue which we call its HLB. The HLB of ICI emulsifiers is shown in all current ICI emulsifier literature, and similar values may be calculated or estimated by various means for any emulsifier. Methods for determining this HLB value are discussed in Chapter 7. The HLB of an emulsifier is an expression of its Hydrophile-Lipophile Balance, i.e. the balance of the size and strength of the hydrophilic(water-loving or polar) and the lipophilic (oilloving or non-polar) groups of the emulsifier. All emulsifiers consist of a molecule that combines both hydrophilic and lipophilic groups. An emulsifier that is lipophilic in character is assigned a low HLB number (below 9.0), and one that is hydrophilic is assigned a high HLB number (above 11.0). Those in the range of 9-11 are intermediate. When twoor more emulsifiers are blended, the resulting HLB of the blend is easily calculated. For example, suppose you want to determine the HLB value of a blend comprising 70% of TWEEN 80 (HLB = 15) and 30% Of SPAN 80 (HLB = 4-3). The calculation would be: TWEEN 80 SPAN 80 70% X 15.0 = 10.5 30% X 4.3 = 1.3 HLB of blend = 11.8
What the HLB System Does To help save time in emulsifier selection, ICIintroduced in the late 1940's a systematic scheme of centering down on the relatively few emulsifiers suitable for any given application. This is called the HLB System - the letters HLB standing for "Hydrophile-Lipophile Balance. Briefly, the HLB System enables you to assign a number to the ingredient or combination of ingredients you want to emulsify, and then to choose an emulsifier or blend ofemulsifiers having this same number. At least, this is the principle of the system. In practice, unfortunately, the task is never simple. But the HLB System does provide a useful guide a series of beacons to steer you through channels where virtually no other markers exist.
Where the HLB System Can Help Most Our discussion here will assume that you have had some experience in making emulsions. A...