Formulating manual dishwash detergents: an optimum hand dishwash liquid formula can be developed by using LAS, SLES and cocamidopropyl betaine and perhaps some cocamide DEA. Read on to learn how to develop a variety dishwash detergents.
FOAM, VISCOSITY AND CREASE cutting power are some of the basic requirements for manual dishwash detergent. Go a little further than the basic formula and it may require good foam stability and a certain pH range. Still not satisfied? Try adding performance in hard water and cold temperatures. Want still more? Throw in quick rinsing and drying. For even more discerning consumers, add mildness and moisturizing effects. Or, how about adding benefits such as naturally-derived, DfE-approved and readily biodegradable? Last, but not least, some formulators add aromatherapy and antibacterial effects.
Let's start with the basics--foam, viscosity and grease cutting--and create a very economical formula, one with the raw material cost of 5-10 cents per 16oz. So, if you can get a bottle, cap and label and the labor for about 15-25 cents, the total cost of a 16oz. dishwash detergent in a bottle ready to be shipped to a customer can be between 20-35 cents. The formula is simple. It has 95% water, 0.63% sodium hydroxide (50% solution), 2.4% DDBSA DDBSA Dodecylbenzene Sulfonic Acid (Pilot's Calsoft LAS-99), 1.2% cocamide DEA (Pilot's Calamidc C), 0.77% sodium chloride and preservatives and dye as required. The blending procedure is easy. Add the ingredients in the order listed with continuous mixing until a clear, smooth and homogenous batch is obtained that is free of lumps and particles. Adjust the pH to 8-9 with DDBSA or sodium hydroxide.
To make an economy formula, start with economy ingredients. DDBSA is one of the lowest cost anionic surfactants in its class, as is cocamide DEA. Together, these two ingredients bring the essentials of a manual dishwash performance attributes to the formula. DDBSA is generally sold as 95% plus active material. With today's high shipping costs it is an obvious advantage. Cocamide DEA is also a high active material with no water or solvent in it. Neutralized DDBSA is an excellent foamer with good detergency de·ter·gen·cy
The power or quality of cleansing.
Noun 1. detergency - detergent quality; the quality of having cleansing power
usefulness, utility - the quality of being of practical use and oily soil removal capabilities. Cocamide DEA adds foam enhancement and stability, emulsification and viscosity building properties. The formula listed above has a viscosity of 200 cp. at 70[degrees]F, as measured by Brookfield RV viscometer using spindle number 3 at 20 RPM. We can develop a wide range of formulas using essentially the DDBSA, sodium hydroxide and cocamide DEA and perhaps some tetra-sodium EDTA EDTA: see chelating agents. or sodium citrate as builders for water softening. So, for example, using the two surfactants, caustic soda neutralized DDBSA (also called sodium alkyl alkyl /al·kyl/ (al´k'l) the monovalent radical formed when an aliphatic hydrocarbon loses one hydrogen atom.
n. benzene sulfonate sul·fo·nate
A salt or ester of sulfonic acid.
1. To introduce one or more sulfonic acid groups into an organic compound.
2. To treat with sulfonic acid. ) and cocamide DEA and, optionally, some EDTA and salt, we can build formulas for hand dishwash liquids with increasing active contents to fit various categories on a retailer's shelf. The categories can include economy, medium grade and premium. Also, the same formulas with little modifications can be used for pots and pan cleaners in I&I applications. The formulas are listed in Table 1 on the following page. All amounts are listed in weight percents.
Table 1. Hand Dishwash Formulas Economy Medium Premium Water to 100% Sodium hydroxide 50% 1.26 2.52 5.04 DDBSA (Pilot's LAS-99) 4.80 9.60 19.20 Cocamide DEA (Pilot's Calamide C) 1.20 1.20 2.40 pH adjustment Adjust pH to 8-9 by DDBSA or sodium hydroxide Sodium chloride 1.0 1.2 Preservative, perfume, dye Q.S Q.S Q.S % Solids 7.63 13.26 24.12 Viscosity (Cp.) at 70[degrees] F 300 700 5500 Ross Miles Foam Height mm 0.1% in D.I water Initial 100 120 135 After 5 min. 85 105 125 National Brand (37% solids) Initial 140 After 5 min. 140
The most economical way to add sodium alkyl benzene sulfonate is to neutralize the DDBSA while making the batch. Make sure your mixing tank and agitator arc constructed of a material that can take pH extremes. The preferred procedure for neutralization neutralization, chemical reaction, according to the Arrhenius theory of acids and bases, in which a water solution of acid is mixed with a water solution of base to form a salt and water; this reaction is complete only if the resulting solution has neither acidic nor of DDBSA is to add the formula amount of water into the mixing tank and start mixing. Add the formula amount of sodium hydroxide 50% solution and then slowly add the DDBSA. Adjust the mixer speed so that it will mix the contents well but at the same time will not generate excessive foaming. Remember, you are handling strong alkali and strong acid, so be careful as these are corrosive material, read MSDS MSDS Material Safety Data Sheets, see there and take appropriate precautions. Also, this neutralization reaction is exothermic exothermic /exo·ther·mic/ (-ther´mik) marked or accompanied by evolution of heat; liberating heat or energy.
ex·o·ther·mic or ex·o·ther·mal
1. . It generates a considerable amount of heat. So also take precautions to accommodate the heat generation, particularly if you are manufacturing a large batch with big amounts of DDBSA and sodium hydroxide. Alternatively, you can buy pre-neutralized material as well. It will probably cost more but may be worthwhile in some instances. Pre-neutralized materials or the sodium salts of DDBSA, also called sodium linear alkyl benzene sulfonate or sodium LAS, are available in 30-, 40-, 50-and 60% active varieties. Some of these materials may contain a hydrotrope (sodium xylene xylene (zī`lēn) or dimethylbenzene (dī'mĕthəlbĕn`zēn), C6H4(CH3)2 sulfonate) to reduce the viscosity and make the product easier to handle. Others that do not contain a hydrotrope, may come in a paste or gel form. These high viscosity versions need special handling and storage.
The foam height data listed in Table 1 shows that the national brand commercial product has better foam stability than the premium formula made with LAS and alkanolamide. So, the obvious question is, how to increase the foam stability? We tried adding lauramine oxide and cocamido-propyl betaine betaine /be·ta·ine/ (be´tah-en) the carboxylic acid derived by oxidation of choline; it acts as a transmethylating metabolic intermediate and is used in the treatment of homocystinuria. to the medium formula. First we added 3% active lauramine oxide to the "medium" formula. The initial foam height increased to 130mm but it dropped 120mm after five minutes. When 3% active cocami-dopropyl betaine was added to the "medium formula" the initial foam height increased to 135mm and after five minutes it dropped to 130mm. This shows that in LAS-based formulas, the cocamidopropyl betaine may be a better choice as a secondary surfactant Surfactant Definition
Surfactant is a complex naturally occurring substance made of six lipids (fats) and four proteins that is produced in the lungs. It can also be manufactured synthetically. than lauramine oxide. Polymers like cellulose ethers (hydroxypropyl methykellulose, for example) can also be used as foam stabilizers although they may not be as economical as amine oxides and betaines, will take longer to process and will not add to the foam volume in any considerable quantity.
We then tried using sodium lauryl sulfate Noun 1. sodium lauryl sulfate - a caustic detergent useful for removing grease; although commonly included in personal care items (shampoos and toothpastes etc. and sodium laureth-2 sulfate as primary surfactants in dishwash formulas. We chose the medium formula and replaced the LAS with equal amount of active SLS. The initial foam height, as well as the height after five minutes, was the same as those listed for the LAS based formula (initial, 120mm and after 5 min., 105mm).
Next we made a modification to the medium formula by replacing LAS with an equal active amount of SLES (SuSE Linux Enterprise Server) See SuSE Linux. (2 mole EO). This formula showed a slight reduction in initial foam height compared to the LAS formula but an improvement in the foam stability (foam height after five minutes). The initial foam height was 115mm and after five minutes it dropped to 110mm.
In light of these experiments and their results, an optimum hand dishwash liquid formula can be developed by using LAS, SLES, and cocamidopropyl betaine and perhaps some cocamide DEA. Let us develop a 15% active formula using these surfactants. A starting formula can be made using 6% active LAS, 4% active SLES, 3% active cocamidopropyl betaine and 2% cocamide DEA. This formula, when diluted 0.1% with deionized water, gave an initial foam height of 135mm and five minutes later the foam went down to 133mm (Ross Miles foam test). In contrast, when lauramine oxide was substituted for cocamidopropyl betaine in the above-mentioned formula, the initial foam height was 120mm and after five minutes it went down to 115mm. That means cocamidopropyl betaine is a better secondary surfactant in an LAS/SLES formula than lauramine oxide.
One or two percent of tetrasodium EDTA or sodium citrate can be added to this formula as a builder; viscosity can be reduced by adding SXS, propylene glycol or denatured ethyl alcohol. A naturally-derived product can be formulated using SLES, cocamide DEA and cocamidopropyl betaine. SLES will give better foam stability than LAS, particularly in hard water. A DEA-free formula can be developed by using LAS, SLES and cocamidopropyl betaine. A sulfate-free and DEA-free formula can be developed using LAS and cocamidopropyl betaine. Both surfactants are listed on the Cleangredients' database used by EPA's Design for Environment.
Alkyl diphenyloxide disulsonates (AD-PODS), such as Calfax DB-45 from Pilot Chemical Co., is an excellent additive to improve cold water efficacy and low streaking and spotting properties in hand dishwashing formulas. These powerful anionic surfactants have excellent hydrophilic hydrophilic /hy·dro·phil·ic/ (-fil´ik) readily absorbing moisture; hygroscopic; having strongly polar groups that readily interact with water.
adj. properties and act as hydrotropes as well as surfactants. AD PODS can also help create ultra concentrated detergents. They reduce the viscosity of high active surfactant solutions and, unlike sodium xylene sulfonate, also add to percent active surfactant in the formula.
To create mild and skin friendly dishwashing liquids, use SLES with three moles of EO like Pilot's Calfoam ES-303. Cocamidopropyl betaine can be added for improved mildness. Other amphoterics like sodium lauroamphoacetate can also be used for mildness. Aloe vera, vitamin E, panthenol, glycerin glycerin /glyc·er·in/ (-in) a clear, colorless, syrupy liquid used as a laxative, an osmotic diuretic to reduce intraocular pressure, a demulcent in cough preparations, and a humectant and solvent for drugs. Cf. glycerol. and other herbal extracts can be added to the formula for skin care benefits in premium products. Essential oils, such as lavender and rosemary, can be used for aromatherapy benefits. Triclosan is commonly used as an antibacterial agent. To claim antibacterial/antimicrobial efficacy, the product must be registered with appropriate regulatory agencies such as FDA and EPA EPA eicosapentaenoic acid.
n.pr See acid, eicosapentaenoic.
About the Author
Shoab Arif is manager, applications & tech service, at Pilot Chemical Company.
Shoaib Arif * Pilot Chemical Co. * Cincinnati, OH