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How to formulate lauryl sulfate-free products: here's a useful guide for the cosmetic chemist who is challenged to create lauryl sulfate-free personal care products.

LAURYL SULFATES have been used for personal cleansing in the U.S. since the mid-1940s. They were considered an improvement over "castile" shampoos which were based on liquid soaps composed of saponified vegetable oils. Lauryl sulfates were found to provide a significant improvement in foam properties, whereas soap shampoos form insoluble calcium soaps in hard water, causing depressed foam and soap buildups. An acid rinse was required to remove the insoluble calcium soap. (1)

In the 1950s, sulfates from ethoxylated lauryl alcohol were introduced. They provided greater solubility that enabled the formulator to develop higher active formulations. The ether sulfates were found to be better solubilizers for fragrance oils and milder than lauryl sulfates (see Tables I and II). (2) Also, the irritation of the ether sulfates can be greatly reduced by blending with a sulfosuccinate or amphoteric. Lauryl sulfates are less responsive to reduced irritation when blended with a mild surfactant. (3,4,5)

Today, lauryl and laureth sulfates continue to be the "workhorse" surfactants in practically all personal cleansers: shampoos, body wash, liquid hand soaps and facial cleansers. Properties such as foam, viscosity-building, light color and low odor are unsurpassed compared to other major surfactants offered on the market.

In recent years, however, there has been a trend among some consumer product companies to replace lauryl sulfates in personal cleansers. Lauryl sulfate surfactants have received bad press over the internet and as a result, some manufacturers have decided to reformulate their products in order to avoid controversy.

There is no surfactant available on the market that will directly replace lauryl sulfate and maintain the identical properties. Compromises are necessary. With proper formulation techniques, however, lauryl sulfate-free formulas can be developed that are more mild and in some cases have improved properties, such as viscosity-building and conditioning. Although there are other options, this article offers alternative surfactants and model formulas to enable chemists to formulate quality lauryl sulfate-free products.

Sodium Cocosulfate

Sodium cocosulfate is prepared by the sulfation of coco alcohol which is derived from the hydrogenation of coconut oil fatty acids at high temperature and pressure. The product is typically supplied as a 90% active solid in either a flake or needle form. The needle is the preferred form since it is less dusty when handled.

In recent years, sodium cocosulfate has become a popular choice as a replacement for sodium lauryl sulfate for several reasons:

* It has a more natural-sounding name. Many companies, especially those promoting natural products, prefer a name with a natural-sounding as opposed to a chemical-sounding name.

* It is an excellent viscosity builder and therefore can replace an alkanol amide or a fatty betaine.

* It has a noticeable conditioning effect on hair, whereas lauryl (a laureth) sulfate simply cleans. (6)

Sodium cocosulfate is used in a wide range of products either as a replacement for sodium lauryl sulfate or to enhance the qualities of a formula; i.e., conditioning and viscosity-building. Applications currently on the market include:

* Conditioning shampoos,

* Liquid hand soaps,

* Body washes,

* Bath beads,

* Toothpaste,

* Synthetic detergent bars and

* Facial cleansers.

Sodium cocosulfate is an excellent replacement for sodium lauryl sulfate because it provides viscosity building properties and a rich dense foam. It is also a useful replacement for diethanolamides which have come under attack in recent years as potential carcinogens. (7,8) The following model body wash formula is an example where a combination of sodium cocosulfate betaine, and an amphoteric can replace the traditional lauryl sulfate/ DEA amide system.
Emollient Body Wash
(Amide and Lauryl Sulfate Free)

Ingredients %Wt.

Mackam HPL-28 (McIntyre) 22.0
 (sodium lauroamphoacetate)
Mackam LMB (McIntyre) 16.0
 (lauramidopropyl betaine, 30%)
(Mackol CAS-100N) (McIntyre) 7.0
 (sodium cocosulfate, 90%)
Mackalene 426 (McIntyre) 2.5
 (isostearamidopropyl morpholine
 lactate, 25%)
Mackester EGDS (McIntyre) 1.5
 (glycol distearate)
Mackernium C-14U (McIntyre) 0.5
 (guar hydroxpropyltrimonium chloride)
Paragon MEPB (McIntyre) q.s.
 (phenoxyethanol (and) methylparaben
 (and) ethylparaben (and) butylparaben
 (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 at
room temperature (no heat) and blend for
one hour. Add the first five components and
heat to 75[degrees]C. Blend until completely
homogenous. Adjust pH with citric acid and
cool. At 50[degrees]C add preservative, EDTA and
fragrance. Cool and fill.


The body wash is a viscous pearly liquid. It provides a rich creamy lather and has an emollient afterfeel.

Creamy Texture

Sodium cocosulfate is also ideal for products that require a creamy consistency; e.g., shave cream or facial cleansers. When combined with a mild disodium lauryl sulfosuccinate, a smooth creamy product can be developed which is ideal for dispensing from a tube. The following is an example of a shave cream formula combining sodium cocosulfate with disodium lauryl sulfosuccinate to provide a shave cream with a creamy texture:
Shave Cream

Ingredients %Wt.

Phase A
Water 33.9
Mackernium C-14U (McIntyre) 0.4
 (guar hydroxypropyltrimonium chloride)
Glycerin 7.0
Mackol CAS-100N (McIntyre) 6.0
 (sodium cocosulfate (90%)
Sodium chloride 0.5
EDTA (40%) 0.2
Citric acid q.s. to pH 6.0-7.0
Phase B
Mackanate LO (McIntyre) 52.0
 (disodium lauryl sulfosuccinate (40%)
Paragon MEPB (McIntyre) q.s.
 (phenoxyethanol (and) methylparaben(and)
 ethyl paraben (and)
 propylparaben (and) butylparaben)
Fragrance q.s.

Procedure:

Disperse Mackernium C-14U into room
temperature water. Heat to 40[degrees]C and maintain
for 30 minutes. Add glycerin, EDTA and
sodium chloride. Heat to 65[degrees]C and slowly
add Mackol CAS-100N. Heat Mackanate LO
to 50[degrees]C and add Paragon MEPB and EDTA.
Slowly add Phase A to Phase B. Blend and
add fragrance. Cool and fill.


Formulating Toothpaste

Sodium cocosulfate is also used in toothpaste to replace sodium lauryl sulfate as the primary foamer and cleaning agent. The following formula is ideal for promotion to the "natural" market.
Toothpaste

Ingredients %Wt.

Phase A
Sorbitol (70%) 31.85
Glycerin 10.00
Mackol CAS-100N (90%) (McIntyre) 0.60
 (sodium cocosulfate)
Phase B
CMC PH-6000 powder (TIC Gums) 0.45
 (cellulose gum)
Phase C
Dicalcium phosphate dihydrate 45.00
Monoammonium glycyrrizinate 0.30
Phase D
Water 11.20
Sodium benzoate 0.25
Phase E
Peppermint oil 0.25
Spearmint oil 0.10

Procedure:

In jacketed, stainless steel kettle equipped
with in-tank homogenizer mixing and sweep
agitation, combine phase A materials and
heat to 80-82[degrees]C. Under homogenization, add
phase B and disperse uniformly (batch will
produce foam). Add phase C to batch with
same sheer and continue homogenization
until all powder has been incorporated.
Immediately add premixed phase D until
uniformly incorporated. Switch to slow,
sweep agitation and begin cooling batch
slowly to 40-45[degrees]C to remove any aeration. At
this temperature range, add phase E. Add
water to batch and cool to 30-35[degrees]C.
Compensate for water loss then compare top
and bottom samples to standard. Finished
product is a thick paste suitable for dispensing
from a tube.


Clear Products

Sodium cocosulfate has low solubility in water, but when combined with a betaine, amphoteric and propylene glycol, a clear product can be achieved. The following is an example of a clear hand soap.
Clear Emollient Liquid Hand Soap

Ingredients: %Wt.

Mackam 35UL (McIntyre) 12.0
 (cocamidopropyl betaine, 30%)
Mackam HPC-32 (McIntyre)
 (sodium cocoamphoacetate, 32%) 10.0
Propylene glycol 7.5
Mackol CAS-100N (McIntyre) 5.5
 (sodium cocosulfate, 90%)
EDTA (40%) 0.2
Citric acid q.s. to pH 6.5-7.0
Mackstat SHG (McIntyre) q.s.
 (sodium hydroxymethylglycinate)
Water, dye, fragrance q.s. to 100.0

Procedure:

Add the first five components to water and
heat to 70[degrees]C. Blend until the Mackol CAS-100N
is melted and dispersed. Cool to 50[degrees]C
and adjust pH with citric acid. Cool to 35[degrees]C.
Add Mackstat SHG. Cool and fill. Product is
a clear, viscous, free-flowing liquid.


Alpha Olefin Sulfonate

Sodium [C.sub.14-16] olefin sulfonate (AOS) is another excellent replacement for lauryl sulfates. It has been used for many years in personal cleansers and is known to provide excellent foam properties and detergency. (9) There are several differences between alpha olefin sulfonates (AOS) and sodium lauryl sulfate. For example, AOS requires a higher amount of viscosity builder (amide, betaine, electrolyte, etc.) to achieve equal viscosity of a lauryl sulfate formula when formulated at the same active level. Also, AOS typically is not as lightly colored as sodium lauryl sulfate and therefore water white or blue colors cannot be achieved.

The following model formula for a 2:1 shampoo was developed with sodium alpha olefin sulfonate in place of sodium lauryl sulfate. Note that the formula also contains cocamide MIPA as a viscosity builder and foam stabilizer instead of the traditional cocamide MEA. The reason is that cocamide MIPA was chosen because it has no free diethanolamine, whereas cocamide MEA contains trace amounts of diethanolamine which can be unacceptable to some consumers. Also, the isostearmidopropyl morpholine lactate used in this formula was found to provide excellent conditioning without depressing foam. Eye and skin irritation are very low. (10,11,12)
2:1 Silicone-Free Shampoo

Ingredients: %Wt.

Sodium [C.sub.14-16] olefin sulfonate, 40%) 25.0
Mackanate EL (McIntyre) 15.0
 (disodium laureth sulfosuccinate, 40%)
Makamide CPA (McIntyre) 3.0
 (cocamide MIPA)
Mackernium 007 (McIntyre) 6.0
 (polyquaternium 7, 9.2%)
Mackalene 426 (McIntyre) 8.0
 (isostearamidopropyl morpholine
 lactate, 25%)
Mackester EGDS (McIntyre) 1.5
 (ethylene glycol distearate)
ETDA (40%) 0.2
Paragon MEPB (McIntyre) q.s.
 (phenoxyethanol (and) methylparaben
 (and) ethylparaben
 (and) propylparaben (and)
 butylparaben
Citric acid q.s. to pH 6.5-7.0
Water, fragrance q.s. to 100.0

Procedure:

Add first seven components to water and
heat to 70[degrees]C. Blend until the Mackamide
CPA and Mackester EGDS are melted and
dispersed. Cool to 50[degrees]C and add fragrance
and Paragon MEPB. Adjust pH to 6.5-7.0
with citric acid if needed. Cool and fill.
Product is a pearly, viscous, free-flowing
liquid.


Cocoglyceryl Sulfonate

Cocoglyceryl sulfonate is another interesting replacement for lauryl sulfate. A more "non-traditional" surfactant, it provides excellent lather and cleansing properties. When blended properly with conditioners and thickening agents, the cocoglyceryl sulfonate provides excellent cleaning and conditioning properties. The following is an example of a 2:1 silicone free shampoo based on cocoglyceryl sulfonate, mild surfactants and conditioners compatible with anionic surfactants.
2:1 Silicone-Free Shampoo

Ingredients: %Wt.

Sodium alkyl [C.sub.10-16] 12.0
 (glyceryl sulfonate, 50%)
Mackanate EL (McIntyre) 20.0
 (disodium laureth
 sulfosuccinate, 40%)
Mackalene 426 (McIntyre) 6.0
 (isostearamidopropyl morpholine
 lactate, 25%)
Mackernium 007 (McIntyre) 4.0
 (polyquaternium-7, 9.2%)
Mackamide CPA (McIntyre) 4.0
 (cocamide MIPA)
Mackester EGDS 1.5
 (ethylene glycol distearate)
ETDA (40%) 0.2
Phenagon PDI (McIntyre) q.s.
 (phenoxyethanol (and) DMDM
 hydantoin (and) iodopropynyl
 butylcarbamate)
Citric acid q.s. to pH 6.0-6.5
Water, fragrance q.s. to 100.0

Procedure:

Dissolve the Mackernium 007 in water. Add
the other components (except fragrance and
preservative) and heat to 70-[degrees]C. Blend until
the Mackester EGDS and Mackamide CPA
are melted and dispersed. Cool to 50-[degrees]C and
add Phenagon PDI and fragrance. Cool and
fill. Product is a pearly, viscous, free-flowing
liquid.


Alkylamido Betaines

Alkylamido betaines are another replacement for lauryl (or laureth) sulfates in personal care cleansing formulations. Betaines have excellent foam and cleaning properties without the need to include an additional foam booster. (13) A betaine-based formula also has the added advantage for products that are required to be anionic surfactant-free. Anionic-free formulas are important for antibacterial cleansers because the active ingredient may be deactivated by anionic surfactants. The following is an example of a clear liquid hand soap based on a lauramidopropyl betaine, which utilizes hydroxethyl cellulose as a thickener and polyquaternium-7 to provide a smooth feel to the skin. Similar products, such as body washes and shampoos can also be formulated with a few minor modifications.
Clear, Anionic-Free Liquid Hand Soap

Ingredients: % Wt.

Mackam LMB (McIntyre) 30.0
 (lauramidopropyl betaine, 35%)
Mackernium 007 (McIntyre) 2.0
 (polyquaternium-7, 9.2%)
Natrosol 250HHR 1.0
 (hydroxyethyl cellulose)
Paragon q.s.
 (DMDM hydantioin (and)
 methylparaben (and)
 propylene glycol)
EDTA (40%) 0.2
Water, fragrance, dye q.s. to 100.0

Procedure

Slowly disperse Natrosol 250HHR in water.
Blend until completely hydrated (approximately
one hour). Add Mackernium 007 and
blend until completely dispersed. Add
Mackam LMB and EDTA and heat to 40[degrees]C.
Add Paragon and blend until clear. Add fragrance,
dye and blend until clear. Adjust pH
to 6.5-7.0 with citric acid if needed. Product
is a clear, free-flowing liquid.


Conclusion

In today's ever-changing market, an ingredient that is widely-favored one day may fall out of favor the next. For example, diethanolamides were the traditional viscosity builder and foam stabilizer in cleansing products for more than 50 years. Then in December 1997, the National Toxicology Program published a report that diethanolamine (DEA) when applied to the skin induced liver and kidney cancers. (14) The results were reported to the public on February 22, 1998 by CBS Morning News. (15) The effect on the industry was that many companies decided to reformulate so they could remove the word DEA from their label to avoid possible public controversy.

There are other examples in the industry, such as nitrosamine-free, dioxane-free, acrylamide-free, ethoxylate-free and animal-free that have resulted in product reformulations. It is difficult to know at this time whether "lauryl sulfate-free" will become a major trend, or remain in the niche market. The purpose of this article is to address the questions "how to reformulate" and not "why to reformulate." The why is often traced to special interest groups and not necessarily based on sound science.

The formulas presented in this article serve as a useful guide to the formulator who is given the challenge to develop a "lauryl sulfate-free" product. Compromises are needed to achieve this goal, but by using creative formulating techniques, lauryl sulfate free cleansers with equivalent (or improved) properties to traditional lauryl sulfate products are possible.
Table I: Eye Irritation Scores of Common Surfactants

 Draize Score

Lauramide DEA 59
Cocamidopropylamine oxide 59
Sodium [C.sub.14-16] olefin sulfonate 39
Sodium lauryl sulfate 32
Cocamidopropyl betaine 24
Sodium laureth sulfate 22
Disodium lauryl sulfosuccinate 18
Disodium laureth sulfosuccinate 14
Disodium cocoamphodiacetate 12
Disodium oleamido MEA sulfosuccinate 4

Table II: Skin Irritation Scores of Common Surfactants

 Draize Score
Sodium [C.sub.14-16] olefin sulfonate 5.5
Sodium lauryl sulfate 5.0
Sodium laureth sulfate 4.7
Cocamidopropylamine oxide 3.9
Lauramide DEA 3.8
Cocamidopropyl betaine 3.8
Disodium lauryl sulfosuccinate 3.4
Disodium laureth sulfosuccinate 1.4
Disodium cocoamphodiacetate 1.0
Disodium oleamido MEA sulfosuccinate 0.9


References

(1.) Schimmel Briefs, March 1947, No. 144, "Synthetic Detergents in Shampoos."

(2.) "A Guide to Formulating Mild Sulfosuccinate Products," McIntyre Group Product Guide, p.7, 2/93.

(3.) T.G. Schoenberg, "Formulating Mild Skin Cleansers," Soap/Cosmetics/Chemical Specialties, May 1983, p. 34A.

(4.) T.G. Schoenberg, "Formulating with Non-Traditional Amhoterics," Cosmetic and Toiletries, Vol. III, No. 10, p. 99.

(5.) T.G. Schoenberg, "Formulating with Betaine and Amphoteric Surfactants," Happi, October 1997.

(6.) T.G. Schoenberg, "Formulating with Sodium Coco-Sulfate, A Non-Traditional Surfactant," Happi, February 2001.

(7.) T.G. Schoenberg, "Formulating without Diethanolamides," Happi, July 1998.

(8.) T.G. Schoenberg, "Formulating without Ethanolamides," Happi, July 1999.

(9.) T.G. Schoenberg, "Formulating [C.sub.14-16] Alpha Olefin Sulfonates in High Foaming Shampoos," Soap/Cosmetics/Chemical Specialties, May 1980.

(10.) T.G. Schoenberg, "New Look at Cationic Surfactants for Today's Low pH Shampoos", Cosmetics and Perfumery, March 1975.

(11.) T.G. Schoenberg, A.A. Scafidi, "Rose of Alkylamidoamine Salts in the Modern Hair Conditioner," Cosmetics and Toiletries, March 1979.

(12.) T.G. Schoenberg, U.S. Patent 4,168,302.

(13.) T.G. Schoenberg, "Formulating with Betaine and Amphoteric Surfactants," Happi, October 1997.

(14.) NTP Board of Science Conselor's Technical Reports Review Sub Committee (Dec. 9, 10, 1997).

(15.) "Major cosmetic and toiletry ingredient poses avoidable cancer risk," R.R. Newswire, February 22, 1998.

Tom Schoenberg

Director of International Sales

McIntyre Group Ltd.

TOM SCHOENBERG is the director of international sales with the McIntyre Group Ltd., University Park, IL. He has more than 40 years of experience in the personal care market. For most of his career, Mr. Schoenberg has been involved in the development of new applications for raw materials. He has published many articles and holds several patents in the area of new and novel products.
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Date:Jun 1, 2004
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