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[laundry chemicals] Surfactants(Surface active agent)

2019-01-18 16:39
● Definition

○ Lowers surface tension by clinging to the surface in the solvent.
(At 1% concentration, the surface tension of water is reduced from 72 mN / m to 30 mN / m or less.)

● Structure

○ hydrophile+hydrophobic

● Characters

○ Dual solvency: Generally there is affinity for water and oil which are opposite to each other

○ e.g.) soap – representative surfactant

● Type of hydrophiles

○ Carboxylic acid salt - COOM / ○ sulfonic acid salt - SO3M / ○ Sulfuric acid ester salt - OSO3M / ○ Amine salt - N + -HX-

○ quaternary ammonium salt - N + -] X- / ○ pyridinium salt - + NN- / ○ hydroxyl group - O H / ○ oxyethylene - CH2CH2O-

● Kinds of oil
Alkyl group - CnH2n + 1 - (n: 8 to 20) / alkylaryl group - CnH2n + 1 - (n: 8 to 15)
- CnH2n + 1 - (n: 3 ~)

● categorizing surfactants

● categorizing ionities

○ Ion surfactants: ionized in aqueous solution.

○ Anion surface active agent: Anionic surface active agent:

○ cation surface active agent: The cationic surfactant (amine type)

○ Amphoteric surface active agent: When the pH is high, the part showing the surfactant is an anion. When the pH is low, the part showing the surfactant is the cation
Nonionic surfactants: do not ionize in aqueous solution (ex-alkyl, phenol, etc.)

● Classified by industrial technology

○ Basic raw material production technology: Technology to manufacture fatty acid, fatty alcohol, linear alkylbenzene, olefin, nonylphenol, etc. using copper, vegetable oil, chemical industry, petrochemical industry

○ Intermediate production technology: It is a technology to produce derivative of small quantity variety through various reaction processes using basic raw materials. Generally, surfactant manufacturing technology refers to such intermediate production technology. Some of the domestic reaction processes (sulfonation, sulfation, ethoxylation, etc.) have been localized, but the technology to localize such as amidation still remains.

○ Application technology: It is the most underdeveloped part in Korea because it contains a lot of know-how as compounding technology to mix final product with various kinds of intermediate product of various kinds of small quantity.

● Characteristics of surfacants

○ Wetting: The surface tension of water is increased by the surfactant because the surfactant absorbs on the interface between air and water and widens the surface.
ex) Plastic surfaces are usually hydrophobic and do not get wet. However, when it is immersed in a surfactant solution, it easily gets wet in water. This is because the hydrophobic component of the surfactant is absorbed on the plastic surface and the outer surface is surrounded by the hydrophilic group. Conversely, a surfactant may act on the hydrophilic surface to produce a hydrophobic material.

○ Micelle: A strong electric field is formed around the micelle which is ionized by the hydrophilic group. Micelles in aqueous solution are thermodynamically stable and are treated as colloidal particles. The inner part of the micelle is a dense region of the hydrophobic group, and when the micellar solution is added with a poorly soluble substance such as benzene, the benzene enters the inner hydrophobic part. At this time, the solution is transparent and appears to be dissolved in benzene, which is called solubilization. Solubilization is used when the chemical fiber is dyed with a pigment hardly soluble in water or when the useful vitamin is dispersed in water.

○ Emulsification: When oil is dispersed in water by a surfactant, an emulsion is formed. This phenomenon is referred to as emulsification. Surfactants are absorbed around oil droplets to stabilize oil droplets. Suspensions are formed when the dispersed particles are solid. This phenomenon is widely used in cosmetics, polymers, and margarine. The surfactant used for easy and stable emulsification is called an emulsifier.

○ Washing: It is an important function of surfactant to clean dirt on fiber or metal surface. The cleaning action has various properties such as absorption, wetting, solubilization and dispersion. The detergent is a product that effectively enhances the cleaning effect of the surfactant. In addition to the detergency, the household detergent needs good solubility, proper foam, wettability, odorlessness, colorlessness, no irritation to the skin, degradation by microorganisms and low toxicity to fish. Phosphate, silicate and the like are added to increase washability.

○ Antistatic Protection: Synthetic fibers and plastics are prone to static electricity, and if the air is dry in winter, it is easy for static to be generated by the fabric. Surfactants can prevent such phenomenon if added to chemical fibers. This is because the surfactant on the fiber surface absorbs water in the air to increase the conductivity.

○ Sterilization: The discovery of quaternary ammonium compounds was done in the early part of the 20th century by German chemist G. Domak. Cationic surfactants contain quaternary ammonium groups, and in aqueous solution this part is positively charged.