Synthetic detergent bars

Simion, F., Rhein, L., Morrison, B., Scala, D., Salko, D., Kligman, A., and Grove, G., Self perceived sensory responses to soap and synthetic detergent bars correlate with clinical signs of irritation. J. Am. Acad. Dermatol. 32 205-211, 1995. 

Synthetic detergent bars deliver much of the same chemistry to the wash as heavy-duty granules. The primary cleaning power comes from anionic surfactants along with phosphate builders such as sodium tripolyphosphate (STPP) and tetra sodium pyro phosphate (TSPP). In India, Latin America, and Africa, LAS is used as the main surfactant, whereas in the Philippines, a combination of alcohol sulfates (preferably coconut based) and LAS is used as the surfactant system. In premium bars, STPP is the preferred builder as it offers, in addition to excellent hardness binding capacity. 

The solubihty characteristics of sodium acyl isethionates allow them to be used in synthetic detergent (syndet) bars. Complex blends of an isethionate and various soaps, free fatty acids, and small amounts of other surfactants reportedly are essentially nonirritant skin cleansers (66). As a rule, the more detersive surfactants, for example alkyl sulfates, a-olefin sulfonates, and alkylaryl sulfonates, are used in limited amounts in skin cleansers. Most skin cleansers are compounded to leave an emollient residue on the skin after rinsing with water. Free fatty acids, alkyl betaines, and some compatible cationic or quaternary compounds have been found to be especially useful. A mildly acidic environment on the skin helps control the growth of resident microbial species. Detergent-based skin cleansers can be formulated with abrasives to remove scaly or hard-to-remove materials from the skin. 

In 1950 the Fischer-Tropsch synthesis was banned in Germany by the allied forces. Sinarol, a high paraffinic kerosene fraction sold by Shell, was used as a substitute. This ban coincided with the rapid development of the European petrochemical industry, and in due time Fischer-Tropsch synthesis applied to the production of paraffins became uneconomic anyway. After the war there was a steady worldwide increase in the demand for surfactants. In order to continually meet the demand for synthetic detergents, the industry was compelled to find a substitute for /z-paraffin. This was achieved by the oligomerization of the propene part of raffinate gases with phosphoric acid catalyst at 200°C and about 20 bars pressure to produce tetrapropene. Tetrapropene was inexpensive, comprising a defined C cut and an olefinic double bond. Instead of the Lewis acid, aluminum chloride, hydrofluoric acid could now be used as a considerably milder, more economical, and easier-to-handle alkylation catalyst [4],... 

Detergent bars are either 100% synthetic detergent or a blend of detergent and soap. They are blended in essentially the same manner as conventional soap. Fairly frequent cleanups generate a wastewater stream. A process flow diagram is shown in Figure 19. 

Personal Care Products. Within the broad definition of synthetic detergents, a variety of cleansing products are made for personal care. These include such products as cleansing bars, shampoos, bubble-bath products, cosmetic cleansers, and tooth pastes. Formulations of these products vary widely, depending upon their intended use. 

In 2004, Draelos and coworkers reported the effect of a petrolatum-containing body wash on the treatment of xerotic eczema. In this study, the researchers found that the patients who used a petrolatum-containing body wash in addition to moderate corticosteroid therapy had improved significantly more than the patients who used a more potent topical corticosteroid and a typical synthetic detergent cleansing bar. Thus, the petrolatum s skin treatment benefits were clearly evident, even when it was contained in a wash-off product.86... 

Almost as a rule, the solubility of soap in water increases with an increase in the size of the monovalent cation (base) however, an increase in the size of a divalent cation (Mg+2, Ca+2) results in a decrease in the solubility. An increase in the chain length of the fatty acid moiety of soap results in a decrease in the solubility of soap, whereas the presence of unsaturation results in an increase in its solubility. In general, an increase in the water solubility is accompanied by an increase in the softness and use-up properties of soap. Adequate solubility results in good performance in soft water, although in hard water, lather decreases due to the formation of insoluble Ca+2 and Mg+2 salts. Cleansing bars formulated with various levels of synthetic detergents (corn-bars or syndets) provide improved performance in hard water conditions. 

Laundry bars can be divided into two main categories—soap bars and syndet bars. In some markets, combars are available, which contain both soap and synthetic detergent Soap bars are generally more mild to the skin than syndet bars, but syndet bars are usually more efficacious, especially at high water hardness. Consumers will choose a laundry bar based on their habits and practices, desired level of efficacy, and their economic situation. 

Soap scum cleaners are by far the largest group of bathroom cleaners. Soap scum is a prevalent problem in almost any bathroom. Hard water deposits are more of a problem in very hard waters area such as Europe, but the precipitatiou of soap caused by hard water salts can become a problem even in areas with moderate hard water. This tends to be less of a problem in households that use shower gels or synthetic detergent (syndet) bars, because the detergents used in these products are... 

Nonsoap detergent bars do not contain soaps. They are synthetic detergents made from petroleum derivatives (Table 6.3) [1-3]. 

SCI, sulfosuccinates, AGES, and CMOS are the main synthetic detergents used in com-bars and syndet bars. The KP of surfactants plays a very important role in the selection of a particular surfactant for the product. Vel Beauty Bar, launched by Colgate in 1948, was the first syndet bar, followed by Zest and Dove in 1952 and 1955, respectively, by P G and Lever Brothers. 

Since the advent of synthetic detergents, there has been active research to overcome a few drawbacks of traditional soap by replacing it with synthetic bars. 

Despite the replacement of soap by synthetic detergents, products for wet shaving continue to be based on soap. Shaving creams and soaps are available as solids, that is, bars creams, generally in tubes or aerosols. Solids are essentially pme soaps applied to the face as foams with a brush. Shaving creams may be nonlathering (emulsion) and rarely consist entirely of lubricating hpids. 

These are named as derivatives of taurine (2-aminoethanesulfonic acid) and are also called taurides. The typical synthetic route involves reaction of sodium bisulfite and ethylene oxide to form sodium isethionate, reaction of the isethionate with methylamine to form sodium iV-methyltaurate, then subsequent reaction with the acyl chloride of a fatty acid to give the iV-acyl-Al-methyltaurate. Taurates have good tolerance to water hardness and find specialty applications in textiles and in detergent bars and shampoos. Taurates are sometimes classified as amphoteric surfactants. 

Most bar soap is indeed soap. A few products consist of synthetic detergent. The products most often used are isethionate esters, alcohol sulfate, and alkyl glyceryl ether sulfonate. 

Applications. a-Sulfo methyl ester surfactants deriving from Qe—Cig fatty acid (e.g., ASMT, the tallowate) are appropriate for use in phosphate-free laundry detergents they have, however, a tendency to generate too much foam in European drum machines when the washing liquid is subjected to extensive mechanical action. The addition of an effective foam inhibitor or soaps can correct this drawback. ASME is also used in the formulation of syndet bars (laundry bars based on synthetic surfactants). 

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