A major component of liquid laundry detergent is based on surfactants that remove soil from the fabric and clean it. A combination of anionic and nonionic surfactants is commonly used for optimum performance. In general, anionics are good for particulate soil removal and nonionics are good for greasy soil removal. Other components of a liquid laundry detergent formula are detailed in this article.  (To keep up with the detergent market trends, click here for the latest launches from Procter & Gamble, Church & Dwight, Dropps and other market leaders).

Thus, a liquid laundry detergent formula can be as simple and economical as say 5% active surfactant solution in water with preservatives. The formula will foam and do some cleaning of the clothes. From here one can improve this basic formula to any desired level in order to enhance the performance and position it for various categories such as economical, mid tier, premium, ultra, and 2X, 3X, 4X etc. Some common additives include:

Builders: Remove the hardness ions so the surfactant can be fully functional. Sodium citrate, tetrasodium EDTA and acrylic polymers are commonly used in liquid laundry detergents.

Antiredeposition agents: Keeps the soil particles suspended in the wash liquor so they do not get deposited back on the fabric. A variety of polymers can be used.

Dye transfer inhibitors: Help prevent dye from coming off one fabric and getting deposited on other. PVP K-30, Chromabond S-100 (PVP with betaine functionality) Chromabond S-400 (PVP with nitrogen oxide functionality) from ISP.

Soil release polymer: Soil release polymers provide a barrier to the fabric, which is removed during the wash, together with the soil. Sorez 100 (polyethylene glycol polyester copolymer) from ISP, Repel-O-Tex SRP-6 (polyethylene glycol polyester) from Rhodia and Texcare SRN 170 from Clariant.

Optical brighteners: Improve the apparent “whiteness” of clothes by absorbing invisible UV light and giving off a blue fluorescence. Tinopal CBS-X from BASF.

Enzymes: For tough stain removal, color and fabric care. Enzymes help remove stains and soils like blood, grass and gravy by breaking them down to smaller, easily removable components. Lipase (0.2%) removes grease and oil; cellulase (0.1%) whitens and brightens; amylase (0.5%) removes starch-based soils; and protease (0.6%) removes protein stains. To stabilize the enzymes, pH should be 7-9; water content (less than 60%), calcium chloride (0.2%), sodium tetraborate (1-2%), propylene glycol (5-10%), sodium formate (1-2%), sodium citrate (3-5%) and monoethanolamine (1%)

pH control: Add citric acid or monoethanolamine to bring pH to desired level.

Viscosity control: Increase or decrease viscosity to desired level with the addition of propylene glycol, sodium xylene sulfonate, polymers.

Suds control: Soap and silicones control excessive foaming.

Preservatives: Microbial control.

Perfume & Dye: Scent and appearance.

Enough talk. Let’s start formulating. Where do we start? Why not start with an economy, really economy, formula; i.e., a formula that is less than 10 cents per pound in raw material cost. Such a formula is a mixture of low cost surfactants, thickeners, builders and preservatives. So if we take 2.5% of DDBSA like Pilot Chemical’s LAS-99 and neutralize it with about 0.65% of 50% caustic soda in water to a pH of 8-10 and then add 1% of cocamide DEA (Calamide C) and 1% of sodium citrate and add a suitable dye and preservative then this will be our economy, or rather, ultra economy, formula. This formula will have a pH of about 9.0 and viscosity of about 100 cp. at 70°F.

Some may think, “This ultra economy formula does not have many of the ingredients listed above.”
Well, that is what you get for less than 10 cents a pound. This formula will foam and do some cleaning of the fabric, but of course will not perform as a premium laundry detergent. Dig a little deeper into your pocket and we can add at least some more ingredients to this basic ultra economic formula. How about we go to an economy formula from the ultra economy we listed above? To be honest, you may have to spend around 12-15 cents a pound in the raw material cost for this upgrade from ultra economy to economy formula. Remember the formulation magic can only go so far—after that you get what you pay for.

Here is the economy formula:
Take 86.7% water, add 1.3% of sodium hydroxide (50%). Start mixing. Add 5% of DDBSA (Calsoft LAS-99—Pilot). Mix well until complete neutralization. Add 3% of alcohol ethoxylate (Tomadol 25-7—Air Products) and 1% each of lauramine oxide (Caloxamine LO—Pilot), Cocamide DEA (Calamide C—Pilot), tetrasodium EDTA (Versene 220—Dow Chemical) and a hydrophobically-modified acrylate polymer (Aculyn 22—Dow Chemical). Mix well and adjust the pH to 9-10 with DDBSA or sodium hydroxide. Add preservative, dye and perfume. Mix well until a smooth, homogenous batch is obtained. This formula is about 9% solids with a pH of 9-10 and a viscosity of 500-1000 cp. at 25°C (Brookfield RV, spindle 3 speed 20 RPM). Some companies also offer blends for laundry applications. Blends offer some advantages such as convenience, less storage space, less chances of error and batch-to-batch variations. Pilot offers a blend called Calsuds CD-6. An economy formula can be made by diluting 10% of this blend with water.

Mid-Tier Detergents
Both ultra economy and economy liquid laundry detergents can be classified as value brand products. Let us continue our journey and climb to the mid-tier. Needless to say, this detergent costs more than the value detergent. The raw material cost may go to 20-30 cents a pound (the cost will vary according to the purchase quantity of major ingredients). The solid level will vary from 15-25%. Few differences from economy formulas are as follows:. The medium grade formulas contain surfactants, builders, anti-redeposition agents, optical brighteners and the minor components such as preservative, perfume and dye. We will use a combination of alkyl benzene sulfonate and lauryl ether sulfate as part of the anionic surfactant portion of the formula. For the nonionic portion, we will still use an alcohol ethoxylate. In this category we can also choose to stay with the surfactants listed on “Cleangredients” database for DfE approval of the formula. For builders and anti-redeposition, we will add sodium citrate and a polyacrylate. We will also add an optical brightener.

Here’s the formula: Add 72.31% of water in the mixing tank and start mixing. Add 5.04% of sodium hydroxide (50% solution) followed by 9.6% of DDBSA (Calsoft LAS-99, Pilot). Mix well until complete neutralization to pH 7-9. Add 5% of SLES (Calfoam ES-702, Pilot). Mix well until a clear, homogenous solution. Add 2% sodium citrate and 1% polyacrylate (Accusol 445 N, Dow Chemical) followed by 5% of alcohol ethoxylate (Tomadol 25-7, Air Products). Continue mixing. Add 0.05% of optical brightener (Tinopal CBS-X, BASF). Mix well and add the minors with constant mixing.

This formula can be modified to achieve various product positioning and performance attributes. If you like to call it a predominantly naturally-derived formula, replace LAS with sodium lauryl sulfate (Calfoam SLS-30, Pilot). Replace Tomadol 25-7 with a naturally-derived alcohol ethoxylate such as Tomadol L-124. If you want to upgrade the formula to an upper mid-tier formula, add a dye transfer inhibitor and a soil release polymer such as 0.25 % of PVP K-30 (ISP) and 0.4% of Texcare SRN 240 (Clariant).

Premium Formulas
If we can dig a little deeper into our pockets, we can go all out to develop the ultimate liquid laundry detergent, or in other words, make a premium formula. Now we are talking about making a formula with 30-40% solids containing all the ingredients listed in the beginning of this article. Here we will use a combination of three anionic surfactants, two nonionics and an amine oxide. For builder we will stay with sodium citrate. We will use PVP NO (Chromabond S-400—ISP) and Texcare SRN 170 for dye transfer inhibition, soil release and antiredeposition effects. Also let us add some oleic acid soap for suds control. For an optical brightener, let us use Tinopal CBX (BASF) and for pH adjustment, we will go with citric acid and monoethanolamine. Try propylene glycol and sodium diphenyloxide disulfonates (Calfax DB-45, Pilot) for viscosity control and coupling. The disulfonates are excellent anionic surfactants as well as hydrotropes and couplers. In premium 2X or 3X laundry detergent formulas, they increase the activity of the formula, but at the same time, lower the viscosity and also perform the coupling action. This is a unique benefit of disulfonates. Most surfactants will increase the viscosity of the formula and may even cause gelling. Disulfonates are also stable in chlorine bleach, peroxide, alkalis and acids. That is why they can be used in a wide variety of HI&I cleaners.

Don’t forget the enzymes. They offer enhanced performance on various kinds of soils including grease and protein. Enzymes also help clothes look whiter and brighter. Enzymes are somewhat delicate materials, however, and must be treated with a little TLC. That includes slow mixing when processing a batch, avoiding hot temperatures, using less water and more actives and, finally, adding enzyme stabilizers to the formula. Enzyme stabilizers include propylene glycol, monoethanolamine, calcium chloride, borax, sodium citrate and sodium formate. Enzymes used in our premium formula are included further in the article.

All right, let’s get to work and develop a nice premium 3X liquid laundry detergent formula.

How It Works
For the surfactant part of the formula we need a well-rounded and balanced combination that can clean various kinds of soils. I suggest we use a combination of linear alkyl benzene sulfonate (Pilot’s LAS-99 neutralized with potassium hydroxide), diphenyl ether disulfonate (Pilot’s Calfax DBA-70 neutralized with potassium hydroxide), alkyl ether sulfate (Pilot’s Calfoam ES-603), alcohol ethoxylate (Air Products’ Tomadol 1-7) and amine oxide (Pilot’s Caloxamine LO).

Let us also use some builders like sodium citrate. For soil release, antiredeposition and dye transfer inhibition we will use a combination of PVPNO (Chromabond S-400 ISP) and a modified polyester copolymer (Sorez 100 ISP). How about Tinopal CBS-X from BASF as optical brightener? I know you would agree to use some silicone antifoam for suds control, something like Dow Corning’s 1520 antifoam. For enzymes we will go with lipase (Novozyme’s Lipolase 100 L), protease (Novozyme’s Savinase 16 L), amylase (Termamyl 300 L) and cellulase (Novozyme’s Carezyme 4500 L). The rest of the ingredients listed below will act as enzyme stabilizer, viscosity modifier, foam control agents and pH buffers. These include calcium chloride, sodium formate, propylene glycol, borax, monoethanolamine and potassium oleate.

Let us go to the lab and prepare a sample of the premium 3X liquid laundry detergent. First add deionized water (29.15%), followed by potassium hydroxide 45% solution (6.1%) in an appropriate beaker. Start mixing and slowly add Calsoft LAS-99 (10%) and Calfax DBA-70 (5%). Mix slowly to avoid excessive foaming for 10-15 minutes. Add oleic acid (3%) and mix well. Check the pH and adjust to 7-9, if necessary, with Calsoft LAS-99 or potassium hydroxide. With continuous mixing add 0.5% Dow Corning 1520 antifoam, 15% Tomadol 1-7 and 7% propylene glycol. Then add 10.0% Calfoam ES-603 and 3.0% Caloxamine LO. Mix well at slow speed. Add 3.0% sodium citrate, 1.0% sodium format, 0.2% calcium chloride, 1.0% borax, 1.0% monoethanolamine, 0.6% Chromabond S-400, 0.6% Sorez 100, 0.05% Tinopal CBS-X. Mix well and cool the batch down to room temperature if necessary before adding the enzymes. Add 0.3% of Carezyme 4500 L, 0.5% Lipolase 100L, 1.5% Savinase 16 L and 1.5% Termamyl 300L. Add preservatives, perfume and dye as required and mix well.

About the Author:
SHOAIB ARIF is manager, home and personal care applications at Pilot Chemical Co., Cincinnati, OH. Previously, he was manager of technology at Degussa Corp. He has also worked for Noveon, Witco and Olin Chemicals. Arif has more than 30 years experience in surfactant applications, technical service, product development and formulations involving personal care and HI&I products.
He can be reached at 513-939-6150 or via e-mail at sarif@pilotchemical.com.