1. Surfactant

There are many types of surfactants. According to their output, they are: anionic 56%, non-ionic 36%, zwitterionic 5%, and cation 3%.

2. Anionic Surfactant

2.1 Anionic surfactant sulfonate. Commonly used in this type are sodium linear alkylbenzene sulfonate and sodium α-alkenyl sulfonate. Sodium linear alkyl benzene sulfonate, also known as LAS or ABS, is a white or light yellow powder or flake solid, soluble in water, although it has poor water solubility at lower temperatures, and its solubility in water at room temperature is below 3. But it has good solubility in the compound surfactant system.

Alpha-alkenyl sodium sulfonate is also known as AOS. When the active content is 38%-40%, the appearance is a yellow transparent liquid, which is easily soluble in water. It has good stability in a wide range of pH values. It has little irritation to the skin and the microbial degradation rate is 100%. Among them, LAS is generally not used in shampoos, and rarely used in shower liquids. It is often used in liquid laundry detergents and detergents (tableware liquid lotions). The LAS in the detergent can account for about half of the total surfactant, and the actual adjustment range of the proportion of LA in the liquid detergent for clothing is very wide.

AOS has the best performance among the sulfonate varieties. It has the advantages of general sulfonates or its advantages are more prominent, without the defects of general sulfonates. AOS is one of the main surfactants commonly used in shampoos and shower liquids. The application in other liquid detergents will gradually increase with the realization of product localization (price reduction). The outstanding advantages of AOS are good stability, good water solubility, good compatibility, low irritation, and ideal microbial degradation; the outstanding disadvantage is that the price is more expensive among anionic surfactants.

2.2 Anionic surfactant sulfate

Common such active agents are fatty alcohol polyoxyethylene ether sodium sulfate and sodium lauryl sulfate. Fatty alcohol polyoxyethylene ether sodium sulfate is alias AES, alcohol ether sodium sulfate. It is easily soluble in water, the appearance is light yellow viscous liquid (translucent) when the active content is 70%, and the stability is inferior to general sulfonates. It is hydrolyzed quickly below pH4, but has good hydrolytic stability in alkaline environment.

Sodium lauryl sulfate is also aliased as AS, K12, sodium cocoyl sulfate, sodium lauryl sulfate, foaming agent. It is soluble in water, and the solubility in water at 25°C is about 15, but the degree of water solubility is inferior to AES. It is not sensitive to alkali and hard water, but the stability under acidic conditions is inferior to general sulfonate, close to AES, long-term heating should not exceed 95 ℃, irritation is at the middle level of surfactant, 10% solution irritation index 3.3, high Lower than AES, lower than LAS.

AES can be used in shampoo, shower liquid, liquid dishwashing detergent (dishwashing liquid), and liquid detergent for clothing. In application, if the pH value quality index permits, the pH value should be adjusted as high as possible, such as neutral or alkaline. When AES must be used under low pH conditions (in shampoos), its ethanolamine salt is generally used. The water solubility of AES is better than that of AS; it can be prepared into any proportion of transparent aqueous solution at room temperature. AES is not only more widely used in liquid detergents than LAS, but also has better compatibility; it can be combined with many surfactants in binary or multiple combinations to form a transparent aqueous solution. Among synthetic surfactants, AES ranks third in output, and the price is lower than that of AS. In 2002, 70% AES was sold at 8,500 yuan/t. The outstanding advantages of AES are low irritation, good water solubility, good compatibility, and good performance in preventing skin dryness and roughness; the disadvantage is that the stability in acidic media is slightly poor-the pH must be controlled to be much greater than 4, and the detergency is inferior to LAS, AS.

AS is used in liquid detergents, pay attention to the pH medium condition-the acidity is not too high; the ethanolamine salt or ammonium salt must be used in the shampoo; the ethanolamine salt or ammonium salt is often used in the shower liquid. Using its ethanolamine salt can not only increase the acid resistance stability, but also help reduce irritation. 10% triethanolamine salt stimulation index 3.0. The application frequency of AS in liquid dishwashing detergents is low, and it is rarely used as the main surfactant, that is, the amount of formula is small. The main reason is that it is unfavorable to reduce product costs. Secondly, this type of product has almost no requirement for foaming. AS ranks No. 5 in the production of synthetic surfactants, and the price is relatively high. In 2002, the powdered price was 15,000 yuan/t. Except for good foaming and strong detergency, AS is not as good as AES in other aspects. For example, the acid resistance and stability are slightly worse, and the irritation is relatively large—just less than LAS, and the price is the highest among the common anionic surfactants.

3. Nonionic Surfactant

The main varieties of non-ionic surfactants are alkyl alcohol amides (FFA), fatty alcohol polyoxyethylene ethers (AE), alkyl phenol polyoxyethylene ethers (APE or OP). Non-ionic surfactants have good solubilization, washing, antistatic, low irritation, calcium soap dispersion, etc.; the actual applicable pH range is wider than general ionic surfactants; it removes dirt and foaming properties. , Other properties are often better than general anionic surfactants. Experiments show that adding a small amount of non-ionic surfactants to ionic surfactants can increase the surface activity of the system—compared with the same active content.

Alkyl alcohol amides are a class of non-ionic surfactants with superior performance, wide range of uses and high frequency of use. They are commonly used in various liquid detergents. Alkyl alcohol amides commonly used specifications in liquid detergents are “2:1 amide” and “1.5:1 amide”, and “1:1 amide” can also be used. These three specifications have different performances in terms of water solubility and thickening. Generally speaking, “1.5:1 amide” is more moderate, and it is mostly used in detergent. Usually, “1:1 amide” is used in combination with other water-soluble surfactants to dissolve easily. Alkyl alcohol amides are more suitable for alkaline detergents, and can also be used in general acidic detergents. Alkyl alcohol amide is one of the cheapest non-ionic surfactants, the price in 2002 was 7,800 yuan/t. Alkyl alcohol amides are used more frequently in liquid detergents than fatty alcohol polyoxyethylene alcohols. The nonionic surfactants used in shampoos are often alkyl alcohol amides. The reasons may be: FFA’s comprehensive functions are better or more than AE; FFA products are less expensive than AE; FFA’s solubility is better than AE; FFA’s foaming property is better than AE.

4. Zwitterionic surfactants

Amphoteric surfactants refer to surfactants with both anionic and cationic hydrophilic groups, so this surfactant is cationic in acidic solutions, anionic in alkaline solutions, and similar in neutral solutions Non-ionic nature. Amphoteric surfactants are easily soluble in water, soluble in concentrated acid and alkali solutions, and can even be dissolved in concentrated solutions of inorganic salts. They have good hard water resistance, low skin irritation, good fabric softness, and antistatic properties. Good, has a good bactericidal effect, and has good compatibility with various surfactants.

This kind of product can be applied in a wide pH range, but from the point of view of the corresponding ionic state under different acid-base medium conditions, the performance under acidic and neutral conditions should be better than that under alkaline conditions. Generally speaking, the price of zwitterionic surfactants is higher than that of nonionic surfactants.

Important amphoteric surfactant varieties include dodecyl dimethyl betaine, carboxylate type imidazoline and so on. Compared with anionic surfactants, nonionic surfactants have more comprehensive performance and fewer defects—only detergency and foaming are worse; compared with nonionic surfactants, some properties of amphoteric surfactants are better , The other performance is not lagging behind. Amphoteric surfactants have better foaming ability than general nonionic surfactants — poor foaming ability of AE; better bacteric5. Cationic surfactant

Common cationic surfactant varieties include cetyl dimethyl ammonium chloride (1631), octadecyl trimethyl ammonium chloride (1831), cationic guar gum (C-14S), cationic panthenol, cationic Silicone oil, dodecyl dimethyl amine oxide (OB-2) and so on. Cationic surfactants are different from other surfactants. They have poor detergency and foaming properties, and often have a certain degree of irritating toxicity (low).

Cationic surfactants are used as co-surfactants in liquid detergents—a conditioner component with a small amount of formula; They are generally used in higher-end products, mainly used in shampoos. Cationic surfactants are not directly compatible with anionic surfactants. The compatibility of cations and anions may produce good results, but the risk of precipitation (crystallization) is greater.

There are many types of cationic surfactants used in shampoos, and the frequency of use is also relatively scattered-instead of using one or two types intensively, they are often formulated into conditioners. Cationic surfactants have a small output share in surfactants, and their prices are often more expensive than other types of surfactants. Compared with various types of surfactants, cationic surfactants have the most prominent adjustment effect and the strongest bactericidal effect; despite the disadvantages of poor detergency, poor foaming, poor compatibility, high irritation, and high price, they are the conditioning agent component in high-end liquid detergent shampoos cannot be replaced by other types of surfactants. It is worth noting that cationic surfactants can only be used as conditioning agent components or bactericides.