THE HLB SYSTEMTHE HLB SYSTEM

THE HLB SYSTEM

Formulating an Emulsion

• Emulsions are one of the most common forms of

cosmetic products

• An Emulsion is a dispersion of two or more immiscible

materials where one phase (internal) is dispersed in the

continuous (external) phase

THE HLB SYSTEM

Formulating an Emulsion• Multiple types, but most common is O/W

• When faced with task of making an emulsion, you have a

choice of hundreds of emulsifiers

• Out of these, you need to select one or two

• HOW?…HLB System

THE HLB SYSTEM

What is the HLB SYSTEM?

• Time Saving, Systematic Guide to Nonionic Emulsifier

Selection

• HLB stands for Hydrophile Lipophile Balance

• “Balance” means:

• All emulsifiers have a part of the molecule that is

water soluble & corresponding part of the molecule

that is oil soluble

• The ratio of one to another on a molecular weight

basis is the “Balance”

• Developed for use in the late 1940’s* by William C. Griffin

(Atlas Powder Company)

*1949 Presented to SCC Chicago Chapter; published in Journal of the

Society of Cosmetic Chemists

THE HLB SYSTEM

HLB System• We use nonionic surfactants to create emulsions

• Nonionic surfactants are molecules that have a

lipophilic/hydrophobic (oil soluble) portion and

hydrophilic/lipophobic (water soluble) portion

• The hydrophilic group is often a polyhydric alcohol (-OH) or

EO

• The lipophilic group is often a fatty acid or a fatty alcohol

• They act as emulsifiers by lowering the interfacial

tension and decreasing the coalescence of dispersed

droplets

THE HLB SYSTEM

Importance of Lowest Interfacial Tension• When two immiscible materials are placed in contact, an interface

results.

• The force causing each material to resist breaking up into smaller particle(s) is called interfacial tension.

• An addition of an emulsifier (s) lowers the interfacial tension making two materials miscible.

• The lowest interfacial tension results in better efficiency of the system, i.e.

– Minimize mechanical energy req’d to form the emulsion

– Minimize the amount of workload on the emulsifier(s) at the interface to fight coalescence of the droplets

– Minimize emulsifier concentration

– Save money

– Impact on sensory of the emulsion

THE HLB SYSTEM

Interfacial Tension

The emulsifier (surfactant) reduces the interfacial tension

and gives rise to smaller droplets and a reduced

tendency of the droplets to flow together (coalescence)

when mixing.

Forces(tension) between

the two phases occurs at the

Interface.

THE HLB SYSTEM

The “Logic” of HLB• All nonionic emulsifiers have an HLB Value

– the higher the number, the more hydrophilic (water

soluble)

– the lower the number, the more lipophilic (oil soluble)

• Emulsion oils have a specific HLB Requirement

Matching HLB requirement (oil) with HLB Value

(emulsifier) yields optimum performance

So how do you determine the HLB Value??

THE HLB SYSTEM

Calculating HLB Values• The most simple way of calculating the HLB

value of a nonionic emulsifier:

• Calculate hydrophilic portion on molecular weight % basis

• Divide that number by “5” (for ease) (~20)

THE HLB SYSTEM

Calculating HLB Value: Example • Oleth-20 is a 20 mole ethoxylate of oleyl alcohol

• We calculate the molecular weight of the 20 moles of ethylene oxide ( one mole ETO =44 )(hydrophilic portion)

� 20 x 44 = 880

• We add this number to the molecular weight of the oleylalcohol

� 880+ 268 (MW=oleyl alcohol) = 1148 (MW of Oleth-20)

• What percentage is the hydrophilic portion, i.e. of 1148 is 880 ?

� 880/1148 = 76.6%

• 76.6 divided by 5 = 15.3

� 15.3 is the HLB value of Oleth-20

• 15.3 is a relatively high HLB so we know it will be more water soluble

THE HLB SYSTEM

Calculating HLB Value: Example • Laureth-4 is a 4 mole ethoxylate of lauryl alcohol

• We calculate the molecular weight of the 4 moles of EO

• ( one mole ETO =44 )

� 4 x 44= 176

• We add this number to the molecular weight of the lauryl alcohol

� 176+ 186 (MW=lauryl alcohol) = 362 (MW of laureth-4)

• What percentage of 362 is 176 ?

� 176/362 = 48.6%

• 48.6 divided by 5 = 9.7

� 9.7 is the HLB value of Laureth-4

THE HLB SYSTEM

Calculating HLB Value: Example Blend�a 50 / 50 blend of steareth-2 and steareth-21

�50% times the HLB value of the steareth-2

• 0.5 X 4.9 = 2.45

�50% times the HLB value of the steareth-21

• 0.5 X 15.5 = 7.75

�2.45 + 7.75 = 10.2

�10.2 is the HLB Value of a 50/50 blend of

steareth-2 and steareth-21The combination of emulsifiers is usually comprised of emulsifier of

high HLB and low HLB allowing good anchoring in both water phase

( high HLB ) and oil phase ( low HLB)

improving stability

THE HLB SYSTEM

Quick Test for an Unknown HLB

Water solubility of the emulsifier(s) can serve as an

approximation of HLB

Behavior when added to water HLB Range

No Dispersibility in Water 1-4

Poor dispersion 3-6

Milky dispersion after shaking 6-8

Stable Milky dispersion 8-10

Translucent to Clear dispersion 10-13

Clear solution 13 +

Let’s try it!

THE HLB SYSTEM

HLB Value…Good News!• You may not have to do this

• HLB value from suppliers, literature, etc.

• Only part of the story…

THE HLB SYSTEM

Required HLB• Like a nonionic surfactant has an HLB value, each

lipophilic ingredient used in an O/W emulsion has an

individual required HLB.

• The required HLB for an oil(s) is the HLB value of the

surfactant that will provide the lowest interfacial tension

between your oil phase and your water phase.

• Interfacial tension (def): the force causing each material

to resist breaking up into smaller particles

• When you are at the lowest interfacial tension between

these two phases, you will need the lowest amount of

surfactant to achieve a stable emulsion.

THE HLB SYSTEM

How is the Required HLB of individual ingredients useful to a formulator?

• Once you know the required HLB of individual

oils, it is easy to calculate the required HLB of

a mixture of oils

• Knowing the required HLB of an oil or an oil

mixture means that you can use the least

amount of emulsifier to achieve emulsification

THE HLB SYSTEM

Typical HLB Requirements for OilsClass Required HLB

Vegetable oil family 5-7

Silicone oils 8-12

Petroleum oils 9-11

Typical emollient ester 10-12

Fatty acids and alcohols 14-15

Paraffinic mineral oil (petro) has a required HLB of 10.

This means that a surfactant, or blend of surfactants having an

HLB of 10 will generally make a more stable & fluid O/W

emulsion with mineral oil than surfactants of any other HLB.

No point trying surfactant or surfactant blend at HLB 8 or 13.

THE HLB SYSTEM

Calculating Required HLB• Each lipophilic ingredient of the oil phase has its

own required HLB

• The required HLB of an oil phase mixture can be

calculated by first calculating the percent of the

oil phase each ingredient contributes

• This percentage is then multiplied by the

required HLB for each ingredient and

summed

THE HLB SYSTEM

Calculating Required HLB

of an Oil Phase Mixture• The oil phase is 10% of the total formula & consists of:

– 4% Shea Butter, 40% of oil phase, Req’d HLB of 8

– 3% Jojoba oil, 30% of oil phase, Req’d HLB of 6.5

– 3% Sunflower seed oil, 30% of the oil phase, Req’d HLB of 7

• Total Required HLB:– Shea Butter contribution: 0.4 x 8=3.20

– Jojoba Oil contribution: 0.3 x 6.5= 1.95

– Sunflower seed oil contribution: 0.3 x 7=2.10

• Total Required HLB= 7.25

THE HLB SYSTEM

Experimental Determination of

Required HLB • What happens when you do not have the required HLB

for all of your oil ingredients?

• Experimental Determination using an HLB “Kit”

• Produce a series of trial emulsions of your ingredients

using emulsifier combinations of known HLB value

• The HLB Value that works best under your trial

conditions is the Required HLB for your set of

ingredients

THE HLB SYSTEM

Blends of Emulsifiers in HLB Kit

HLB Sorbitan Oleate Polysorbate 80

4 100% -

6 83% 17%

8 65% 35%

10 46% 54%

12 28% 72%

14 9% 91%

THE HLB SYSTEM

Required HLB Test• In a series of 2 oz. jars, add:

– 20 gm oil to each jar

– 2 gm emulsifier systems with HLB = 2, 4, 6, 8, 10,12, 14, 16

– Shake well

• Add 28 gm DI water to each jar, shake well

• the blend that separates the least is the required HLB

THE HLB SYSTEM

Determine the Required HLB

6 148 10 12

Use applicable water hardness, pH and temperature

4

O/W

emulsion

W/O

emulsion

if when running a required HLB test you see a “winner” at both the high and low end

of the scale of the test this almost always means the “winner” at the low end is an

invert (w/o) emulsion.

THE HLB SYSTEM

HLB Three-Step System

1) Determine the HLB Requirement of oil

2) Determine the most effective emulsifier

chemistry (HLB Value)

3) Determine emulsifier concentration required

to achieve desired stability/rheology

THE HLB SYSTEM

Select Chemistry…Determine Concentration

All emulsifiers: HLB = 12

----

----

Surf A

8%

Surf B

8%

Surf C

8%

Surf C

6%

Surf C

4%

THE HLB SYSTEM

HLB Values of Blended Components

• The HLB value of an emulsifier blend is the

weighted average of the HLBs of the blended

emulsifiers(e.g. 50 / 50 blend of HLB 4 with HLB 16 = HLB 10)

• The HLB requirement of an oil blend is the

weighted average of the HLB requirements

of the blend components

(e.g. 50 / 50 blend of Req 10 oil with Req 14 = Req 12)

THE HLB SYSTEM

Calculating Required HLBEX: Skin Care Formulation

Ingredients %

Mineral Oil 10

Emollient Ester 5

Fatty Alcohol 4

Silicone 1

Emulsifier 4

Water q.s

Humectant 4

Polymer 0.2

Preservative/

Fragrance

1

Oil Phase to be emulsified

Ingredients % % weight of Oil

Mineral oil 10 50

Emollient Ester 5 25

Fatty Alcohol 4 20

Silicone 1 5

Total Oil Phase 20

Ingredients % Req. HLB

Mineral Oil 50 10.5 5.25

Emollient Ester 25 12 3.0

Fatty Alcohol 20 15.5 3.1

Silicone 5 8 0.4

Required HLB 11.75

THE HLB SYSTEM

HLB by calculation• We should select emulsifier blend with an HLB value ~ 11.75

• Fraction A = (X- HLB(B))/ HLB(A)- HLB(B)

• Fraction B = 1- Fraction (A)

• X= rHLB , A= Emulsifier, B = Co-emulsifier,

If HLB= 11.75,

Sorbitan Oleate = HLB 4.3, Polysorbate 80 = 15.0

Fraction of Polysorbate 80= (11.75-4.3)/(15.0-4.3) = 0.69

Fraction of Sorbitan Oleate = 1- 0.69 =0.31

If we use 5% of total emulsifier ;

Polysorbate 80 = 5% x 0.69 = 3.45

Sorbitan Oleate = 5% x 0.31= 1.55

THE HLB SYSTEM

Summary• The HLB System predicts how oils and

non-ionic emulsifiers will likely interact

• Emulsifiers have HLB values– the higher the number, the more hydrophilic

– the lower the number, the more lipophilic

• Oil(s) have HLB requirements

• Match the emulsifier HLB value with the HLB

requirement

• Determine chemistry & use level…

….optimum performance

THE HLB SYSTEM

Thank you!