Cationic surfactantQuaternary ammonium salts are formed by further alkylation of fatty tertiary amines. Commonly used alkylating agents are methyl chloride or dimethyl phosphate. There are many types of them, and their output ranks first among various cationic surfactants. Quaternary ammonium salts with practical value in industry include the following three categories: long carbon chain quaternary ammonium salts, imidazoline quaternary ammonium salts and pyridine quaternary ammonium salts.
The affinity of the quaternary ammonium salt cation itself It is much more watery than fatty primary amines, fatty secondary amines and fatty tertiary amines, which is enough to dissolve the hydrophobic end required for surface activity into the water. The positive charge on the quaternary ammonium cation allows it to be firmly adsorbed on negatively charged surfaces.
Currently, quaternary ammonium surfactants The biggest use of this agent is as a household fabric softener.
Long carbon chain quaternary ammonium salts are generally All contain more than one long carbon chain alkyl group. They have the highest yield among cationic surfactants. A typical example is dioctadecylbismethylammonium chloride.
Number of carbon atoms in alkyl group Mainly 16~18. In addition to chloride ions, methyl sulfate ions are also used as counter ions.
Dioctadecyldimethyl There are two main routes for the production of ammonium chloride. The starting material of the first method is fatty acid, which is first converted into fatty nitrile and then hydrogenated to generate amine during reduction.
Dioctadecyldimethyl Quaternary ammonium salts are mainly used as softeners in laundry operations. The softening effect comes from the arrangement of the fat tail groups in the molecules adsorbed on the fiber surface. It can smooth the fibers and make the washed clothes achieve the required softness and good feel.
At the same time, the slightly hydrophobic surface caused by cations can prevent the small water droplets contained in the clothes from merging together when drying, thus making the terry cloth surface The down becomes softer.
Long chain of quaternary salts The second use is for organobentonite clay. Organobentonite is a rheology modifier. It is used in the coating industry to control the rheology of paints. It is used in oil field drilling to prepare drilling oil slurries and as lubricants for various metals. The principle of organobentonite controlling the rheology is because it has hydroxyl groups in its molecular structure. Hydrogen bonds can be generated in the standing medium, making the slurry a uniform gel with a certain viscosity. When there is external force (such as stirring), the hydrogen bonds are destroyed and the viscosity becomes smaller. This characteristic is called rheology.
The third use of long-chain quaternary ammonium salts is sterilization. Most of the quaternary salts used for sterilization are in the structure Contains card base. The fields used for sterilization include: household, medical and industrial sterilization, disinfection and mildew prevention; algae killing in swimming pools; disinfection in the laundry process; microbial sterilization in oil fields, etc.
