Detergents characteristics

The main producers worldwide are Shell, Gulf, and Ethyl. The physical and detergency characteristics of a-olefins are affected by the carbon chain length distribution and therefore each new supply may require testing to determine whether the desired properties for the new chosen application can be achieved. The following specifications (Table 12) may be used as a guideline. 

The synthetic detergents industry originated in the 1940s, when it was found that a new anionic surfactant type—alkylbenzene sulfonate—had detergent characteristics superior to those of natural soaps. The first surfactant of this kind was sodium dodecylbenzene sulfonate (SDBS). This material was produced by the Friedel-Crafts alkylation reaction of benzene with propylene tetramer (a mixture of Co olefin isomers), followed by sulfonation with oleum or sulfur trioxide and then neutralization, usually with sodium hydroxide. The alkylation was typically performed using homogenous acid catalysts, such as HF or sulfuric acid. 

Instead of the use of sulfuryl chloride, SO2 and CI2, which combine to give sulfuryl chloride, can be employed for vapor-phase reactions. When the ratio of SO2 to CI2 is adjusted, it is feasible to produce sulfonic or chlorosulfonic acid derivatives of saturated paraffins in liquid-phase reactions. According to Lockwood and Richmond, a premixed stream of sulfur dioxide and chlorine can be used for the countercurrent photochlorination of white oil (petroleum fraction, sp gr, 0.8033 bp, 283-324 C) at about 50°C. The product, after hydrolysis with 30 per cent sodium hydroxide, yields an aqueous solution of the sodium salt of a sulfonic or chlorosulfonic acid. An increase in the ratio of SO2 to CI2 greatly increases the yield of solubilized product. When a 3 1 ratio is used, the product contains very little chlorine and has good wetting and detergent characteristics. ... 

The benchmark feeds indicated in Table 11.2 have been extensively tested in both laboratory and commercial settings and are known to produce MES products of low color and disalt content suitable for use in liquid and powder products. The C16 is preferred over C16-C18 for a sulfonation feedstock because it makes a better color MES and has proven product quality and excellent detergency characteristics it will become more widely available as a feedstock, the economics of producing detergent-grade ME favors C16 (requires less hydrogenation). 

MONA NF-10, NF-15 and NF-25 are low foaming anionic surfactants which are soluble in concentrated alkaline builder solutions. These products differ in their degree of electrolyte tolerance but each provides excellent detergency characteristics. They are recommended for use in spray, soak tank, in-place pipeline cleaners and floor scrubbing formulations. 

The basicity of a detergent is an essential additive characteristic. It is expressed as Total Basic Number (T.B.N.) (ASTM D 664). 

Enzymes are important catalysts in biological organisms and are of increasing use in detergents and sensors. It is of interest to understand not only their adsorption characteristics but also their catalytic activity on the surface. The interplay between adsorption and deactivation has been clearly illustrated [119] as has the ability of a protein to cleave a surface-bound substrate [120]. 

The surface-active agents (surfactants) responsible for wetting, flotation and detergency exhibit rather special and interesting properties characteristic of what are called association colloids or, in the older literature, colloidal electrolytes. These properties play an important role in determining, at least indirectly, the detergency of a given surfactant and are therefore considered here... 

The adsorption of detergent-type molecules on fabrics and at the solid-solution interface in general shows a complexity that might be mentioned briefly. Some fairly characteristic data are shown in Fig. XlIl-15 [242]. There is a break at point A, marking a sudden increase in slope, followed by a maximum in the amount adsorbed. The problem is that if such data represent true equilibrium in a two-component system, it is possible to argue a second law violation (note Problem Xni-14) (although see Ref. 243). 

Starch monophosphates are quite useful in foods because of their superior freeze—thaw stabiUty. As thickeners in frozen gravy and frozen cream pie preparations, they are preferred to other starches. A pregelatinized starch phosphate has been developed (131) which is dispersible in cold water, for use in instant dessert powders and icings and nonfood uses such as core binders for metal molds, in papermaking to improve fold strength and surface characteristics, as a textile size, in aluminum refining, and as a detergent builder. 

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. 

These phenomena are most rapid and easiest to observe in fairly concentrated aqueous detergent solutions, that is, minimally 2—5% detergent solutions. In a practical quaHtative way, this is a familiar effect, and there are many examples of the extraordinary solvency and cleaning power of concentrated detergent solutions, for example, in the case of fabric pretreatment with neat heavy-duty Hquid detergents. Penetration can also be demonstrated at low detergent concentrations. As observed microscopically, the penetration occurs in a characteristic manner with the formation of a sheathlike stmcture, termed myelin they are filled with isotropic Hquid but have a Hquid crystalline birefringent skin. 

Observable Characteristics - Physical State (as normally shipped) Powder or thick liquid Color Pale yellow Odor Faint detergent. 

The information presented in this chapter is intended to provide a brief overview of the composition, performance, and formulation properties of LAS by itself and in combination with other surfactants. The particular performance synergies and processing characteristics of certain combinations of surfactants are discussed briefly. The examples of mixed active formulations provided herein represent to the best of the author s knowledge the approximate levels of major surfactants in actual household detergent products both past and present. This does not imply that these formulations are complete because many additives, such as bleaches, enzymes, builders, hydrotropes, thickeners, perfumes, and coloring agents, may also be present in varying amounts. 

Carbon chain homolog distribution is nearly always the most important factor in determining performance and formulation characteristics of LAS [19]. Phenyl isomer distribution and dialkyltetralinsulfonate content have their greatest impact on the formulation characteristics of LAS in liquid detergents. 

In formulating liquid detergent products with LAS, the carbon chain distribution, phenyl isomer distribution, and DATS level can all contribute to the solubility and viscosity characteristics. Hydrotrope requirements for isotropic liquid detergents can vary widely for different types of commercial LAS. 

Improved formulation characteristics in liquid detergent products... 

Because of its superior solubility characteristics, a high 2-phenyl LAS (with an alkyl chain length average of 11.4) was the preferred type. The detergency performance of one LAS/AE type of formulation was discussed previously (see Figs. 12 and 13). Early commercial heavy-duty liquid (HDL) formulations were built with phosphate, but since 1979 almost all U.S. HDLs have been formulated without phosphate. 

Tallow alcohol sulfate is an important surfactant used in heavy-duty detergents. The unsaturated part of the alkyl chain of tallow alcohol gives their sulfates an improved solubility with excellent detergent and foaming characteristics. 

Alkyl sulfates and alcohol ether sulfates have been established for use in emulsion polymerization. AOS, although it has been used for many detergent applications during the past four decades, does not find any large-scale use as a primary surfactant system in emulsion polymerization. A study by Kreis [92] has shown that AOS surfactants are very well able to produce a small size latex and have excellent foaming characteristics (i.e., foam height and stability) in latex. They should therefore be able to compete with alkyl sulfates and alcohol ether sulfates. 

Often a phosphorus-containing surfactant provides the combination of desired characteristics, e.g., wettability, detergency, and anticorrosiveness. Thus classification by discriminate application is difficult. The following structure only serves the purpose of a better survey. The limits between specific sections are hazy, and as a result the mentioned surfactants encompass more than one characteristic. 

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