Characteristics of surfactants commonly used in detergents
1. Surfactants
There are many types of surfactants, and they account for 56% of anionic surfactants, 36% of nonionic surfactants, 5% of amphoteric surfactants, and 3% of cationic surfactants in terms of production volume.
2.Anionic surfactants
2.1 Anionic surfactants sulfonates are commonly found as sodium straight-chain alkylbenzenesulfonate and sodium α-alkenylsulfonate. Sodium straight-chain alkylbenzene sulfonate, also known as LAS or ABS, is a white or yellowish powdery or flaky solid, soluble in water, although the water solubility is poor at low temperatures, and the solubility in water at room temperature is less than 3, but the solubility is very good in the complex surfactant system. It is stable to alkali, dilute acid and hard water, with decomposition temperature of 240°C. The irritation index of 10% solution is 5.0, the microbial degradation rate is 80%～90%, and the LD50 is 1300～2500mg/kg].
Sodium α-alkenyl sulfonate alias AOS, when the content of active substance is 38%～40%, the appearance is yellow transparent liquid, very soluble in water. It has good stability in a wide range of pH values; 30 ℃ for 3 days, pH2, pH4, pH10, hydrolysis rate are 0. It is less irritating to the skin, microbial degradation rate of 100%, LD50 is 1300 ~ 2400mg / kg. Among them, LAS is not used in shampoo shampoos, and seldom used in the shower liquid, commonly used in clothing liquid detergent and dishwashing liquid detergents (dishes). It is commonly used in liquid detergent for clothes and dishwashing liquid (dishwashing liquid). In detergents, LAS can account for about half of the total surfactants, and in liquid detergents for clothes, the actual adjustment range of the proportion of LAS is very wide.
The water solubility of LAS is mainly reflected at higher temperatures (e.g., 60°C) and in combination with certain surfactants. A typical compounding system used in detergents is the ternary system “LAS-AES-FFA”. A typical compounding system used in liquid detergents for clothes is the three-component system “LAS-AES-FFA”, and the compounding system used in liquid detergents for clothes is “LAS-soap-η-SAA”. It is worth noting that LAS directly compounded with nonionic surfactant alkyl alcohol amide does not necessarily achieve good results, “LAS-FFA” system is unstable and small viscosity and the appearance of white emulsion.LAS is the largest production (290kt/a), the most inexpensive varieties of synthetic surfactants. LAS has the lowest price among the top 5 synthetic surfactants in terms of production volume, and is comparable to soap-based (fatty ester soap) among the common anionic surfactants.The outstanding advantages of LAS are good stability, good detergency, and low price, and the outstanding disadvantage is high irritation.
AOS in the sulfonate varieties, the best performance, with the advantages of general sulfonate or its advantages are more prominent, but does not have the defects of the general sulfonate.AOS is the shampoo shampoo and shower liquid in the common use of one of the main surfactants. The application in other liquid detergents will also be gradually increased with the realization of localization of products (price reduction).The outstanding advantages of AOS are good stability, good water solubility, good compatibility, low irritation, microbial degradation is also very ideal; the outstanding disadvantage is that the price of anionic surfactants is more expensive.
AS in addition to good foaming and decontamination, other aspects of performance are inferior to AES, such as acid stability is slightly worse, irritation is relatively large — just smaller than LAS, in the common anionic surfactants in the price is also the highest.
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