edited and reprinted from CHEMMUNIQUE,
`publication of ICI Americas Inc.
`
`ICI Americas Inc.
`Wilmington, Delaware 19897
`ANTICIPATING NEEDS
`
`1
`
`The
`HLB
`SYSTEM
`
`at
`
`ime-saving
`guide
`to
`emulsifier
`selection
`
`HYDRITE EXHIBIT 1008
`(1 OF 22)
`
`

`
`CHAPTER 1
`
`Meaning of HLB
`Advantages and Limitations
`
`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
`
`2
`
`HLB scale of typical
`ATLAS emulsifiers
`20
`
`TWEEN 20
`
`TWEEN 40
`
`TWEEN 80
`TWEEN 60
`
`TWEEN 21
`
`TWEEN85
`
`TWEEN 65
`
`TWEEN 81
`TWEEN 61
`
`SPAN 20
`
`SPAN 40
`
`SPAN 60
`SPAN80
`
`SPAN 65
`SPAN 85
`
`hydrophilic
`
`10
`
`lipophilic
`
`0
`
`HYDRITE EXHIBIT 1008
`(2 OF 22)
`
`

`
`WHEN you are faced with the problem of making
`an emulsion, you have 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.
`
`What the HLB System Does
`
`To help save time in emulsifier selection, ICI
`introduced 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 of emulsifiers 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
`complete dissertation on the many factors which
`influence your choice of emulsifiers would
`necessarily cover aspects of emulsion technology
`far beyond the HLB System.
`For example, before you can begin making use
`of the HLB System, you must set up some sort of
`evaluation system for your "satisfactory" emulsion.
`Do you want an oil-in-water (O/W) emulsion or a
`water-in-oil (W/O)? How stable do you want your
`emulsion, in storage? -in use? What are your cost
`limits? Should your emulsifier be stable toward
`alkalies, salts, or electrolytes? Must it be non-toxic
`
`3
`
`-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 of emulsifier?
`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
`numerical value 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 (oil-
`loving 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 two or 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
`
`As you will discover in applying the HLB
`System, the HLB of an emulsifier or blend of
`emulsifiers is an excellent indication of what the
`emulsifier system will do, that is, whether it will
`make an oil-in-water (O/W) emulsion or a W/O
`emulsion, or act as a solubilizer for some oil. The
`HLB of an emulsifier class or blend is also an
`
`HYDRITE EXHIBIT 1008
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`
`

`
`indication of the efficiency of chemically-related
`emulsifiers or of a blended pair of emulsifiers for
`performing any given emulsifier task.
`When you consider a variety of chemical types
`of emulsifier, and classify them according to struc-
`ture, each class covers a segment of the HLB range.
`The efficiency of these classes differs. HLB is not
`an indication of the relative efficiency of one class
`to another. This "class efficiency" seems to be
`related more to chemical structure (that is, whether
`the emulsifier is a soap, a partial ester, a complete
`ester, whether the lipophilic group is saturated, etc.)
`and the relationship of its chemical structure to the
`chemical structure of the material to be emulsified.
`Subsequent chapters in this book will give you
`some guides to comparison of chemical types when
`the "ideal" HLB of emulsifier for your application
`has been determined, although no specific rules
`have been established for this step in emulsifier
`selection.
`
`HLB Related to Solubility
`
`The HLB of an emulsifier is related to its
`solubility. Thus, an emulsifier having a low HLB
`will tend to be oil-soluble, and one having a high
`HLB will tend to be water-soluble, although two
`emulsifiers may have the same HLB and yet exhibit
`quite different solubility characteristics.
`
`Anyone who works with emulsifiers soon
`becomes aware of the relationship between the
`solubility of an emulsifier and its behavior. For
`
`example, you will use a "water-soluble" emulsifier
`or blend to make an O/W emulsion, or to solubilize
`oils, or to obtain detergent action. In other words,
`you use a "water-soluble" emulsifier when you
`to exhibit aqueous
`want your final product
`characteristics, i.e. to dilute readily with water. For
`these purposes, you would
`rarely use an
`"oil-soluble" emulsifying system. On the other
`hand, if you wanted to make a W/O emulsion, or
`couple watersoluble materials into an oil, or
`produce some other type of non-aqueous emulsion
`system, you would
`choose
`an oil-soluble
`emulsifier.
`From experience, then, you would expect that the
`functions of emulsifiers might well be classified by
`HLB, and this is true. Table I shows some
`interesting general correlations.
`
`Table 1
`
`HLB Range
`4-6
`7-9
`8-18
`13-15
`10-18
`
`Use
`W/O emulsifiers
`Wetting agents
`O/W emulsifiers
`Detergents
`Solubilizers
`
`These correlations are based on long experience
`with ICI emulsifiers, and are amazingly accurate,
`although certain exceptions have been found. For
`example, a few excellent detergents have been
`found in the HLB range 11-13.
`
`HLB
`10
`
`HLB
`10
`
`HLB
`10
`
`0
`
`O
`
`20
`
`W
`
`0
`
`O
`
`20
`
`W
`
`0
`
`O
`
`20
`
`W
`
`When oil-loving groups in surfactant
`are predominant, HLB is low... for
`producing water-in-oil emulsions.
`
`When water-loving groups predominate,
`the surfactant has high HLB and is
`used for oil-in-water emulsions.
`
`When oil-loving and water-loving
`groups are fairly well balanced,
`HLB is intermediate (around 10).
`
`4
`
`HYDRITE EXHIBIT 1008
`(4 OF 22)
`
`

`
`CHAPTER 2
`
`"Required HLB" for Typical Ingredients
` to be Emulsified
`
`The "Required HLB" of an Ingredient
`
`Through long experience in using the HLB
`System, ICI emulsion technologists have found that
`all oils, waxes and other materials likely to be
`incorporated into emulsions have an individual
`"Required HLB." For instance, in Table 2A, you
`will see that the required HLB for a fluid O/W,
`emulsion of paraffin is 10.
`
`This means that an emulsifier, or blend of
`emulsifiers, having an HLB of 10 will make a more
`stable fluid O/W paraffin emulsion than emulsifiers
`of any other HLB value. It does not mean that
`every emulsifier or blend having an HLB of 10 will
`"work" - you might have an "HLB 10" emulsifier of
`the "wrong" chemical family (wrong for this
`purpose, at least). However, you can be assured that
`when you're working with any certain family of
`emulsifiers, you will obtain optimum results more
`quickly if you work in the area of HLB 10, say ± 1.
`You'd be wasting time to try emulsifier blends at
`HLB 8 or 13, for example, unless you might
`happen to be looking for a particular quality other
`than stability in your emulsion.
`Do not make the mistake of assuming, from this
`preliminary working data,
`that you
`should
`immediately try all single emulsifiers in the catalog
`that have an HLB of 10 for your paraffin emulsion.
`Remember, you can blend emulsifiers to make any
`HLB you want, and blends usually work best. In
`Chapters 5 and 6, emulsifier blends and selection of
`"chemical families" for trial will be discussed more
`fully.
`
`It is important to remember that, as noted in
`Table 2 this HLB of 10 is for a 10-20% paraffin
`wax fluid O/W emulsion made by propeller mixing.
`If you want an emulsion of different concentration,
`composition or viscosity-or made by a different
`method-its required HLB will likely be different.
`Differences in supplies and batches of oils and
`waxes can also result in variations in required HLB.
`
`Required HLB for Ingredient Blends
`
`Table 2 gives you some idea of the required HLB
`values for O/W emulsions of various oils and
`waxes that you are likely to encounter most
`frequently. From these values, you can calculate
`required HLB values for blends of these oils and
`waxes, each component contributing its share to the
`whole.
`For example, suppose you are making an O/W
`emulsion textile lubricant. The product might be
`30% mineral spirits, 50% cottonseed oil and 20%
`chlorinated paraffin to be emulsified in water. The
`required HLB of the combination can be calculated
`as follows:
`
`Mineral Spirits ..........30% X Req. HLB 14 = 4.2
`Cottonseed Oil ..........50% X Req. HLB 6 = 3.0
`Chlorinated Paraffin . . 20% X Req. HLB 14 = 2.8
` _______
`Estimated HLB for emulsifier system ..........10.0
`
`You should ckeck this estimated value with a few
`exploratory tests in the range of say 9-11, as shown
`in Chapter 3, but you know from this calculation
`
`5
`
`HYDRITE EXHIBIT 1008
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`
`

`
`
`
`
`
`Method of Determining Above Required HLB Values
`
`The figures in Table 2A, which supersede similar
`values published by ICI in other literature, represent the
`Required HLB for O/W emulsions containing 20% (or
`less) of the material to be emulsified.
`In most cases, 2.5% to 5% of several emulsifier blends
`was tried, blended to HLB values 2 units apart in the
`range from 4 to 18. The material to be emulsified, if
`liquid, was blended with emulsifier at room temperature.
`Solids were blended at 10 ºC above necessary melting
`point. Water was added with propeller agitation, at room
`temperature for liquids, or heated to 15 °C higher than
`temperature of solids.
`After determination of the best one or two emulsions,
`4 or 5 more emulsions were prepared with emulsifier
`_____________________________________________
`
`that emulsifier combinations in this range will
`probably give best results.
`This method of calculating required HLB is often
`useful for fluid types of emulsions, but is not
`usually practical for "solid" cream type emulsions
`or very heavy lotions. In this latter type of
`emulsion, an excess of lipophilic (low HLB)
`emulsifier, such as a stearic acid soap or SPAN 60
`sorbitan monostearate,
`is generally used
`for
`thickening action. Thus the HLB of the emulsifier
`combination employed will be substantially lower
`than the HLB value needed only for emulsification
`or solubilization.
`
`6
`
`blends one HLB unit apart, bracketing the apparently
`best HLB range.
`The Required HLB of any material is likely to vary
`slightly with the source of the material, the concentration
`desired and the method of preparation, and should be
`verified against your own ingredients at your own
`desired concentration and with your own manufacturing
`technique.
`Materials that are surface active, such as fatty acids,
`fatty alcohols, etc., when used at high concentrations,
`will likely require a higher HLB.
`The Required HLB for making W/O emulsions of any
`material will lie in the range of 3 to 8; for solubilization
`in water, in the range of 10 to 18. Typical values are
`shown in Table 2B.
`
`_____________________________________________
`
`Experimental Determination of Required HLB
`If you are so fortunate as to find all your oil
`phase ingredients listed in Table 2A, it is quite easy
`for you to calculate the required HLB of any
`combination of
`these
`ingredients for a fluid
`emulsion. However, what if you're using other oils
`or waxes of unknown "required HLB"? What if you
`want a thick emulsion instead of a fluid ? The HLB
`System provides a refined trial-and-error method of
`determining the required HLB for any combination
`of ingredients to meet your own requirements for
`viscosity and stability. Chapter 3 will discuss this
`method in detail.
`
`HYDRITE EXHIBIT 1008
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`
`

`
`CHAPTER 3
`
`Determining “Required HLB” for Your
`Own Ingredients
`
`If the ingredients of your oil phase are not shown
`in Table 2A, then your next step is to determine the
`required HLB of your
`ingredients by an
`experimental procedure. The HLB System provides
`you with a simple method. Essentially, this method
`consists in actually producing a series of trial
`emulsions of your own
`ingredients, using
`emulsifier combinations of known HLB value. The
`HLB value of the emulsifier system that "works
`best," under your own trial conditions, is the
`"Required HLB" for your set of ingredients.
`
`Even when all the required HLB values of your
`ingredients are published in Table 2A, it is still a
`good idea to run this experimental determination,
`because oils, waxes and solvents from various
`sources vary
`in properties
`'and emulsifying
`characteristics.
`
`Making Trial Emulsions
`
`For your preliminary tests, to determine your
`required HLB, select any matched pair of SPAN
`and TWEEN emulsifiers, i.e. SPAN 20 with
`TWEEN 20 or SPAN 60 with TWEEN 60. This
`will give you two emulsifiers of the same chemical
`class, one
`lipophilic
`(oil-loving),
`the other
`hydrophilic (water-loving). For example, the "20"
`SPAN-TWEEN emulsifiers are both laurate esters;
`the "40"s are palmitate esters; the "60"s are
`stearates; and the "80"s oleates.
`
`The SPAN emulsifiers are lipophilic, the TWEEN
`products hydrophilic.
`This is only a trial run, so you don't care at this
`point whether the emulsifiers you select are perfect
`for your purpose or not.
`
`Suppose you happen to have some SPAN 60 and
`TWEEN 60 on your lab shelf. You can use these
`for your trials. As a start, make up small batches of
`seven emulsifier combinations, ranging in HLB
`from straight SPAN 60 (HLB = 4.7) to a straight
`TWEEN 60 (HLB = 14.9),* as follows:
`
`*HLB values of all ICI surfactants are given in the
`booklet "Genenral Characteristics of ICI Surfactants" (0-
`1), and many representative chemical types are also
`listed in Chapter 6. While the seven test emulsifier
`combinations shown here will usually give you a good
`indication of the "Required HLB" of your oil phase, you
`may find it advisable to try higher HLB values. For
`example, by working with SPAN 20 and TWEEN 20
`instead of SPAN 60 and TWEEN 60, you could try HLB
`values from 8.6 to 16.7.
`
`7
`
`HYDRITE EXHIBIT 1008
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`
`

`
`Now, make seven test emulsions, using one of
`the above emulsifier samples in each. Use an excess
`of emulsifier (say 10-20% of the weight of your oil
`phase), and dissolve or intimately disperse the
`emulsifier into the oil phase, melting ingredients
`together if necessary.
`
`While simple mixing of your ingredients and
`emulsifiers will probably be sufficient at this point
`in your testing, it is important that you use
`preparation methods as nearly identical as possible
`for each of your seven emulsions, simulating your
`own plant methods.
`
`Using the appropriate method or methods for
`comparison and evaluation of your product, you
`will probably notice fairly quickly that one or
`another of these emulsifier combinations will give
`you a better emulsion than the other six, even
`though not necessarily a very good one. If all the
`emulsions seem fairly good, with not much
`noticeable difference, then repeat the seven tests,
`using
`less emulsifier. Conversely,
`if all
`the
`emulsions are poor and show no great difference,
`repeat the tests but use higher emulsifier content.
`
`More often than not, you will be comparing your
`emulsions for stability - you'll be watching for
`separation of ingredients, perhaps in a matter of
`minutes, perhaps overnight, or after heating or after
`freeze-thaw cycles. However, it is entirely possible
`your criterion for a good emulsion might be clarity
`or viscosity, ease of preparation or ease of
`application. Whatever your index for judgment
`might be, these preliminary tests will enable you to
`
`center down on an approximate HLB range (say
`plus-or-minus-one) for the emulsifier system that
`will work best for you.
`
`Suppose you find that an HLB of approximately
`12 is optimum for your purpose. You might then
`make further tests around this value to establish
`this HLB value more accurately, i.e. these same
`two emulsifiers might be blended to try making
`emulsions at HLB values
`ranging step-wise
`between 11 and 13.
`
`In this preliminary test, you may find that you
`get a fairly good emulsion at HLB 4.7 and another
`one at HLB 12.0. If something like this occurs,
`you'll probably find that your "low HLB" emulsion
`is a W/O emulsion (doesn't dilute readily with
`water, doesn't conduct electricity) and your "high
`HLB" emulsion is an O/W emulsion (easily
`water-dispersible,
`conducts
`electricity). Most
`likely, you're trying for an O/W emulsion - the
`usual kind - but that's a matter of your own choice.
`
`Merely by this one easy set of trials, you have
`already narrowed yourself down to a relatively
`small field for further trials of emulsifiers or
`emulsifier blends. Next, you will be looking for the
`ideal chemical type, and a later chapter in this book
`will give you some guideposts for this. Regardless
`of the chemical type finally chosen for your
`emulsifier or blend, it will fall fairly closely within
`the HLB limits you have found in these preliminary
`tests. You'll be wasting your valuable time if you
`bother looking elsewhere in the HLB range for
`your emulsifier answer.
`
`8
`
`HYDRITE EXHIBIT 1008
`(8 OF 22)
`
`

`
`CHAPTER 4
`
`Importance of Blending Emulsifiers and Choosing
`Ideal Chemical Type
`
`Let's assume that you have determined the
`"Required HLB" of your ingredients as outlined in
`Chapter 3. Let's say it's 12.0. It might appear that
`the proper way to proceed now would be to obtain
`all the emulsifiers ICI supplies having an HLB of
`12, or somewhere around 12, and try them.
`However, if you do this, you're very likely
`making a serious mistake. First, you're assuming
`that having the right HLB is enough. Actually,
`however, you must also find the right chemical
`type having the right HLB. Secondly, you're
`missing the opportunity the HLB System gives you
`to tailor-make the ideal emulsifier for your own
`set of ingredients and conditions. By blending two
`emulsifiers, you can arrive at the exact HLB you
`need, instead of trying to "make do" with a single
`emulsifier having an HLB that's "close but not quite
`right." Moreover, you can adjust your emulsifier
`blend to suit your oil or other active ingredients,
`instead of having to limit or adjust your active
`ingredients to suit the emulsifier.
`Bear in mind that the most stable emulsion
`systems usually consist of blends of two or more
`emulsifiers,
`one
`portion
`having
`lipophilic
`tendencies, the other hydrophilic. (For example,
`glyceryl monostearate, self - emulsifying grade, is
`actually a blend of lipophilic non-self-emulsifying
`g.m.s., with a hydrophilic soap or other substance
`to make it more water-soluble.)
`Only in relatively rare instances will you find a
`single emulsifier product to suit your requirements,
`even though it might have the exact HLB you need.
`Sometimes a complex blend is sold as a single
`emulsifier, and this might give you a somewhat
`better chance.
`
`Importance of Chemical Type
`
`Knowing the "Required HLB" of your ingre-
`dients narrows down your choice of emulsifiers
`considerably, but you're still faced with the problem
`of choosing the ideal chemical type of emulsifiers.
`
`At least, when you try different chemical types, you
`won't need to try all sorts of blends of each
`chemical type - but just the one blend having the
`"Required HLB" you need.
`"Right chemical type" is just as important as
`"right HLB." The two go hand in hand. Suppose
`you found that a blend of SPAN 60 and TWEEN 60
`(stearates), at an HLB of 12, gave you a better
`emulsion than any other HLB of these two
`emulsifiers. That HLB of about 12 will be best for
`any chemical type you might try. But now you
`must determine whether some other SPAN-
`TWEEN blend at HLB 12 (say laurates, palmitares
`or oleates) might not be better or more efficient
`than the stearates. Or perhaps some chemical
`family blend outside the popular SPAN-TWEEN
`class might be even more suitable. (In any case,
`remember, it will have an HLB of about 12! )
`
`The "chemical type" of an emulsifier blend is just as important
`as its HLB. For example, at left we see a polyoxyethylene
`sorbitan oleate ester type of emulsifier blend with its
`unsaturated lipophilic oleate "tail" in the oil; an unsaturated
`chain like this seems to "attract" oils having unsaturated
`bonds. At right is another emulsifier blend, similar to the other
`except that it is a stearate; a saturated chain like this (or a
`laurate or palmitate) seems to "attract" saturated oil chains,
`Thus, although both types of oil might "require" an emulsifier
`having an HLB of 12, and both emulsifiers might have this
`HLB, the emulsifier that ''attracts" the oil will be more
`effective.
`
`9
`
`HYDRITE EXHIBIT 1008
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`
`

`
`CHAPTER 5
`
`Calculating Ratio of Emulsifiers to Reach
`Any Desired HLB
`
`Suppose, for example, that you used various
`blends of SPAN 60 and TWEEN 60 (stearates) to
`determine your "Required HLB," as was suggested
`to you in Chapter 3, and let's say you determined
`that your "Required HLB" is about 12.0. Now, you
`might like to try the oleate family of SPAN-
`TWEEN emulsifiers, i.e. SPAN 80 and TWEEN
`80. How much of each do you need to give you an
`HLB of 12.0?
`Here's an easy way to calculate how much of any
`emulsifier (A) to blend with any other emulsifier
`(B), to reach an HLB of X.
`
`Using this formula to calculate how much SPAN
`80 (HLB = 4-3) and how much TWEEN 80 (HLB =
`15.0) you need to arrive at an HLB of 12.0, your
`calculation would be:
`
`then you draw a horizontal line for the HLB value
`you want your blend to have. By drawing a
`perpendicular line through the intersection of your
`two previous lines, you can read off the percentage
`of TWEEN you need, at the top or bottom of the
`graph.
`You can enter the HLB values of any emulsifiers
`you wish along the left and right margins to
`compute HLB of any desired blend.
`
`Blends are Usually Best
`
`We re-emphasize here that blends of emulsifiers
`are nearly always much more effective as
`emulsifiers than any single chemical composition
`would be. Therefore, when you have found the
`
`HLB Computagraph
`
`If you need to make many such calculations, you
`will find it more convenient to use the HLB
`Computagraph, illustrated in Figure 2. An HLB
`Computagraph is included in the center insert to be
`removed and used in a plastic cover or copied for
`your own calculations. On
`the
`reverse are
`precalculated values for surfactant blends.
`In Figure 2, HLB values of the SPAN group are
`marked along the left edge; those of the TWEEN
`group along the right edge; and percentage of
`TWEEN is shown from 0 to 100 across the bottom.
`If you're working with SPAN 20 and TWEEN 20,
`for instance, you merely draw a ruler line from the
`HLB value of one to the HLB value of the other;
`
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`HLB COMPUTAGRAPH
`
`VEEN5“ 20
`
`VEEN 40
`VEEN 80
`VEEN 60
`UEEN 21
`
`VEEN 85
`VEEN 65
`VEEN 81
`UEEN 61
`
`R HIGH HLB
`JRFACTANT)
`
`HLB
`
`S1"-’ANr‘?2Cl
`
`SPAN 40
`
`SPAN so
`853
`
`AN 80
`
`SPAN 65
`
`SPAN 85
`
`1
`
`(OR LOW HLB 0
`SURFACTANT)
`
`6
`
`5
`
`4 3
`
`2
`1
`
`0
`
`0
`
`5
`
`IO 15 20 25 30 35
`
`40
`
`45 50 55
`
`50 55
`
`70
`
`75
`
`30 35 90 95
`
`I00
`
`% HiGH HLB SURFACTANT
`
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`Blend of emulsifiers usually give more stable emulsions than
`any single emulsifier, even though the single emulsifier might
`have the HLB you want. Suppose you want an HLB of 12.6.
`Here are eight emulsifier blends of different chemical families
`- each blend will give you the desired HLB of 12.6.
`
`"Required HLB" for your own set of ingredients,
`don't blindly assume you should now try every
`single emulsifier you can find that happens to have
`this HLB value!
`
`Preliminary Step in Finding
`Ideal Chemical Type
`
`Just to give yourself some idea of a systematic
`procedure for determination of the best chemical
`type to suit your problem, it is suggested that you
`try blends of other SPAN-TWEEN combinations.
`For- example, if you determined your "Required
`HLB" of 12 by trying SPAN 60 blended with
`TWEEN 60, you might now try blending SPAN 20
`with TWEEN 20 (laurates); then try the "40" com-
`bination (palmitates); then the - 80" combination
`(oleates). Only one blend of each is necessary the
`blend having an HLB of 12. You can compute this
`blend easily by algebra or with
`the HLB
`Computagraph.
`You may find that oleates give you the best
`"feel," while stearates give you best viscosity
`control. At the same time, perhaps the laurates give
`you an emulsion of satisfactory stability at
`extremely low emulsifier concentration, so maybe
`you could save money by using them. These
`preliminary findings might well guide you toward
`later experimentation with certain members of other
`chemical groups, if necessary. Likewise, you might
`find that you can obtain ideal results by blending
`one of the SPAN-TWEEN chemical types with
`another - say SPAN 20 with TWEEN 80.
`
`Let's say you have found the "Required HLB" to emulsify your
`oil, by the method outlined in Chapter 3. You found it is 12.
`You decide to compare an ''HLB 12" emulsifier with an ''HLB
`11" of the same chemical class. Here's a theoretical graph of
`the results you might get. In lower left corner, at "zero"
`concentration of emulsifier, we have "zero" emulsion stability.
`At 4% concentration, the emulsifier having HLB 12 produces
`stable emulsions of your ingredients, and greater concen-
`trations produce no greater stability. By contrast, the emulsifier
`having HLB 11 might require a concentration of 8% to produce
`emulsions of equal or less stability than the other emulsifier. So
`you'll I probably save money with the "HLB 12" emulsifier.
`
`is 12 for
`''Required HLB"
`the
`Assume you've found
`emulsifying your oil. Now you're testing three different
`chemical types of emulsifier blends, all having an HLB of 12,
`using the same amount of each type to make trial emulsions. A
`graph of your results would look something like this. All three
`chemical types, ''A", "B'', and "C", would give you best
`emulsion stability in the general area of HLB 12, but one, say
`"A", is by far the best. You might achieve results equal to "A"
`by increasing the amount of "B" or "C". But obviously, all
`emulsifiers having your "Required HLB'' will not give equal
`performance in emulsifying your specific oil. "B" might be
`considered superior to "A" if it is less expensive or if a
`relatively mediocre stability of a wider HLB range is preferable
`to the high narrowrange stability of "A".
`
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`CHAPTER 6
`
`Investigation of Various Chemical Types
`
`in your emulsifier
`the remaining steps
`While
`selection system are still a matter of trial and error, you
`have already learned a great deal about what will work
`and what won't work as emulsifiers in your own
`emulsification system, simply by a few trials of SPAN-
`TWEEN emulsifier combinations blended to meet your
`"Required HLB."
`Your procedure now will be to try to even more
`chemical types, blended to meet your previously deter-
`mined "Required HLB." Occasionally, the "Required
`HLB" for one chemical type may be slightly different
`from that for another chemical type, but at least you
`have a reliable guide to your trials. Thus, if your
`"Required HLB" is 12, and you try another chemical
`family, at HLB ranges from 11 to 13, without getting
`equal or superior emulsifying results as compared with
`your previous trials, you can immediately discard this
`chemical family from further consideration.
`"Recent studies have shown stearic acid and stearyl
`alcohol derivatives consistently out-perform other
`chemical types in a variety of emulsification work.
`When time is limited for investigation of various
`chemical types of surfactants, you would do well to
`concentrate on blends of SPAN 60, TWEEN 60, BRIJ
`72, BRIJ 78, and BRIJ 700."
`
`Tables 3 and 4 as Guides to Investigation of
`Chemical Types
`After you have found the "Required HLB" of your
`oil phase under your own conditions, as discussed in
`Chapter 3, then Tables 3 and 4 on pages 16 to 19 make
`useful guideposts to the chemical types of emulsifiers
`you might try at your predetermined "Required HLB."
`Examine Table 3 first, bearing in mind the appli-
`cation of your emulsion and the "Required HLB" you
`have previously found. In the left-hand column, you
`will find dozens of emulsifier applications in which
`ICI emulsifiers are often used. In the second column is
`the
`reference number of any single surfactant
`suggested for this application. In the third column is
`the reference number of various blends of surfactants
`suggested for trial. Also included here is the HLB
`range suggested for trial of surfactant blends. Your
`own "Required HLB" will likely fall within this range.
`
`14
`
`If possible, find your own application in Table 3, or
`one as nearly like it as you can. Find the reference
`numbers of surfactants and surfactant blends suggested
`for this application.
`Now turn to Table 4 and look up these references.
`Here you will find the trade name and chemical
`identity of the ICI surfactants or surfactant blends
`which ICI would suggest for trial first, based on our
`past experience. This is merely a suggestion, however,
`because your own emulsion of formulation problem
`may be different in many respects from the particular
`examples with which we have had experience in our
`own laboratories. These suggestions will guide you not
`only to specific surfactants, but also to the broad
`"chemical families" they represent.
`Table 4 shows only about half of the total ICI "line"
`of surfactants. Many other surfactants in each of the
`chemical classes shown in Table 4 will be found in the
`booklet "General Characteristics of ICI Surfactants"
`(O-1).
`To see how you can make best use of these
`surfactant suggestions, let's look at an example in
`which both a single surfactant and a blend are
`suggested.
`Let's say you're trying to formulate an O/W anti-
`perspirant cream. In Table 3, under "Cosmetics," you
`find that a typical single surfactant for this purpose is
`Nº 131, and typical blends suggested are Nº 551 and
`the 600 Class.
`Now, turning to Table 4, you find that No. 131 is
`ARLACEL 165, of the glycerol mono- and di-stearate
`class, a blend of mono- and diglycerides with poly-
`oxyethylene stearate. Its HLB is around 11. 0 ± 1. In
`your previous tests to find the "Required HLB" of your
`own ingredients, you probably found that you need a
`surfactant having an HLB more like 16 to 17, for your
`typical stearic-acid based cream. So, you might
`conclude that No. 131 does not fit your needs. In this
`particular case, however, the glycerol monostearate
`portion of the ARLACEL 165 would also serve as part
`of the waxy portion of your cream, so that, by using
`less stearic acid (as is the usual practice in making
`monoglyceride-based
`creams) ARLACEL
`165
`becomes a logical candidate for your trial.
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`Nº 131 itself suggests that you might try other blend