Auto Care Products Formulation (part 2)

Exterior Car Care Agents/Polishes

Silicone oils, especially polydimethylsiloxanes and aminosiloxanes, have been in use in all kinds of polishes for decades. They are common ingredients in car, furniture, and shoe polish for use in household and industrial applications. Despite this, the use of silicone surfactants is still not as well established in polish product formulations and not nearly as well in cleaning systems. Silicone surfactants in this context are silicones modified with polar groups such as polyethers, quaternary, anionic or amphoteric groups, as well as silicone emulsifiers with hydrophilic polyether and hydrophobic alkyl chain moiety. As silicones and aminosiloxanes are not directly water soluble or dispersible, they have to be emulsified to cope with users’ needs in aqueous systems. The derivation of silicones with functional groups like polyethers is leading to silicone surfactants.

These can be incorporated into water or work as emulsifiers and solubilizers on their own. The most important silicone surfactant is polyether siloxane. In a good car polish, for achieving a long-lasting gloss, which is detergent resistant for several washings, it is recommended to use an aminosiloxane. This is usually formulated as oil in water emulsion with emulsifier, thickener, and abrasive and other ingredients.

For the convenience of the production as well as for the improvement of product performance the use of a self-emulsifying aminosiloxane is interesting. It is a clear aminosiloxane which forms an emulsion with water of water/oil (w/o) type without any further emulsifiers or additives.

For all surfaces where stress cracks can come up, like polymethylmethacrylate or polycarbonate, special silicone emulsions free from nonionic surfactants have to be used. Here the emulsifier system is based on anionic materials that are nonethoxylated and therefore prevent stress cracking.

Interior Car Care/Leather Care

The market offers a broad range of special interior cleansers for all kinds of surfaces, e.g., plastics, leather, wood, and fine metal finishes. Antistatic and ultraviolet (UV) protection are market claims for these product groups. The interior cleanser should not interact with plastic materials and should protect materials as well. It should remove greasy spots and create an antistatic effect without visible residues on hard surfaces. The formulation could be with or without alcohol and slightly acidic when the antistatic effect is the main criterion. On the other hand, it could be slightly alkaline for more grease removing capacity with a low antistatic effect.

The refractive index of a silicone emulsifier is quite high and compared to organic emulsifiers it is nearly as crystal clear as other silicone compounds. This effect is already used in the cosmetic industry for the creation of clear gels as antiperspirants and for other applications. A transparent gel system is achieved only when both of the emulsion phases have the same refractive index. In the water phase, by correct selection of polyalcohols like glycerol, polyglycerol, or propylene glycol the refractive index can be adapted very easy. Therefore, the continuous phase, the oil phase, is blended first and the water phase is then made up and added. In cosmetics, skin feel can be improved by these gels, using high amounts of volatile silicone oils. For leather polishes, the use of volatile silicone oils is suitable due to the fact that the cleaning effect of these oils is excellent. In addition, silicone wax which stays on the leather surface for a prolonged period is more important.

Rim/Tire Care

Tire cleaners are formulated to remove the tough road film, grease, grime, and dirt from the tire. They are heavy in caustic and builders. The surfactants used in this application must be stable to high pH and presence of electrolytes. Amphoteric surfactants that can provide performance advantages in this application include sulfobetaines or amphopropionates. Nonionics like amine oxides or alkyl polyglucosides are also used because of their good cleaning ability in alkaline conditions.

This process is accomplished using the same raw materials with different concentrations of builder systems and a different pH range. Chemicals are used in higher concentrations than the car wash soaps with different brushes and pickup systems.

Glass/Windshield Cleansing

Windshield washers are designed to remove greasy soil and dust from the glass. Since the greasy soil is comparatively light and the substrate glass is a hard, nonporous surface, it is easier to clean. Here the important requirement is that the surfactant should not leave spots and streaks. Most formulators use alcohol, generally isopropyl alcohol (IPA), to prevent the formula from freezing. Glycol ethers like di propylene glycol monomethyl ether are used as solvents to dissolve any oil or grease and grime. Ammonia or other suitable alkalies are used to give alkalinity to the formula and enhance the grease removing capacity. Surfactants are used in low amounts of 0.2 to 1.0% to provide the wetting and penetrating action to the formula.

Binary blends of low foaming surfactants also have interesting properties, especially when looking at the blend of capryl/capramidopropyl betaine and decaminoxide on glass or car windshields [8]. The very low wetting effect, i.e., slightly hydrophobic effect created by water-soluble ingredients of the blend, can be of use in glass cleaners for car windshields, as the dilution required to use the product is very easily removed by the wiper. Due to the increasing use of polyacrylate and polycarbonate in car headlights, and the problem of stress cracking, the use of nonionics should no longer be recommended. The formula for a summer product is developed with the objective that the windshield is clear after only one or two strikes of the wiper. A similar formulation for winter is possible with antifreeze agents. As a consequence, an all-season concept does not interfere with the spray jets.

Sources:

• F Müller, J Peggau, Low-foaming Surfactants in Ternary Blends, Jorn Com Esp Deterg 28:1998, 127–136.
• F Müller, J Peggau, Ternary Surfactants in Synergistic Blends, 4th World Conference on Detergents, Montreux 1998, Proceedings of the 4th World Conference on Detergents, A. Cahn ed., Champaign, 1999, pp. 234–237.
• F Müller, J Peggau, Low-Foaming Surfactants in Synergistic Ternary Blends, SÖFW-Journal 125: 1999 5, 2–10.
• J Henning, F Müller, J Peggau, Novel Applications of Silicone Surfactants in Cleaners and Polishes, Jorn Com Esp Deterg 29:1999, 235–246.
• J Henning, F Müller, J Peggau, Novel Applications of Silicone Surfactants in Cleaners and Polishes, SÖFW-Journal 127: 2001 1–2, 38–43.
• I Eissmann, J Henning, F Müller, S Stadtmüller, W/O-Emulsionen, enthaltend aminofunktionelle Organopolysiloxane, German Patent Application (DE) 198 56 930.0, 1998.
• Handbook of detergents, Michael S. Showell, Auto Care and Industrial/Institutional Products, Felix Mueller, Jörg Peggau, and Shoaib Arif.