Formulating with Sodium Cocosulfate, A Non-Traditional Surfactant

Household & Personal Products Industry, Feb, 2001 by Tom Schoenberg

This material provides excellent foam, builds good viscosity, is easy to handle and provides excellent conditioning.

SODIUM COCOSULFATE is an infrequently-used surfactant for personal cleansing products. The primary reason for this lack of use is that most formulators are unfamiliar with the unique properties of this surfactant. When formulating a cleansing compound, such as shampoo, body wash, liquid hand soap or facial cleanser, the anionic surfactant of choice is normally an alcohol sulfate, an ether sulfate or a combination of both. These traditional surfactants have been used for more than 50 years and will continue to be used for several good reasons: they are excellent foamers, build viscosity, are easy to handle and are relatively inexpensive.

Sodium cocosulfate behaves quite differently from sodium lauryl sulfate. The following data compares the general differences found between the two surfactants (see chart below). These varying properties are due to the differences in composition. Sodium lauryl sulfate is a relatively pure compound derived from lauryl alcohol which has excellent solubility and foam properties. Sodium cocosulfate is derived from cocofatty alcohol which is a mixture of alcohols based on the alkyl distribution found in coconut oil. The higher molecular weight fraction accounts for the lower solubility of sodium cocosulfate.

Property              Sodium Lauryl Sulfate   Sodium Cocosulfate

Appearance            Liquid, typically 30%   Anhydrous flake,
                      active                  typically 90% active

Solubility in water   Disperses readily       Requires heat to
                                              disperse

Foam properties       Excellent flash foam    Provides dense lather

Viscosity building    Requires a builder      Excellent. Does not
                      such as amide,          require a builder.
                      betaine or amine        Often requires a
                      oxide                   hydrotrope to
                                              reduce viscosity

Conditioning          Not applicable. Needs   Provides mild
                      added conditioner       conditioning

With proper formulating techniques, sodium cocosulfate can eliminate the need for traditional surfactants such as lauryl sulfates, alkanolamides and betaines. This article will provide guidance in developing unique formulas based on sodium cocosulfate.

The DEA Controversy

Diethanolamides have been reported to be carcinogenic.[1,2,3] Because of this controversy, many companies are reformulating personal cleansing products to be diethanolamide-free. Some have replaced diethanolamide with monoethanolamides; however, since the chemistry of these two surfactants is similar, the latest trend is to have alkanolamide-free formulas.[4,5] Cocosulfate is an excellent choice, as it provides the same viscosity building properties as alkanolamide. There is also a trend among some companies to develop lauryl sulfate-free formulas. A sodium cocosulfate formula can eliminate both concerns. Excellent lather and viscosity are achievable when cocosulfate formulations incorporate amphoteric and betaine surfactants. Here is an excellent body wash formula based on this type of system:

Emollient Body Wash (amide and lauryl sulfate-free)

Ingredients:                                   %Wt.

Mackam HPL-28                                  22.0
  (sodium lauroamphoacetate)
Mackam LMB                                     16.0
  (lauramidopropyl betaine)
Mackol CAS-100F                                 7.0
  (sodium cocosulfate)
Mackalene 426                                    25
  (isostearamidopropyl
  morpholine lactate)
Mackester EGDS                                  1.5
  (glycol distearate)
Mackernium C-14U                                0.6
  (guar hydroxypropyltrimonium
   chloride)
Paragon III                                    q.s.
  (phenoxyethanol (and)
  DMDM hydantoin (and)
  methylparaben (and)
  propylparaben)
EDTA (40%)                                   0.2
Citric acid                      q.s. to pH=6.5-7.0
Water, fragrance                      q.s. to 100.0

Procedure:

Disperse Mackernium C-14U in water (no heat) and blend for one hour. Add the first five ingredients and heat to 75 [degrees] C. Blend until completely homogeneous. Adjust pH with citric acid and cool. At 50 [degrees] C, add preservative, EDTA and fragrance. Cool and fill.

Comments:

The product is a viscous, pearly liquid. It provides rich lather and emollient after-feel.

Clear Cleansers

Sodium cocosulfate has low solubility which is ideal for opaque or pearly products. Clear products, however, can also be formulated with proper balance of the surfactants and a coupling agent. The combination with amphoteric and betaine surfactants provides enhanced foam volume and clarity. The following is a clear conditioning shampoo based on these components. The cocosulfate provides conditioning, thickening and lather properties. This type of system can also be applied to a clear body wash, hand cleanser or facial cleanser.