” >Metal processing includes metal cleaning, surface coating, and metal turning, milling, planing, cobalt, rolling, casting and other processing processes. In order to reduce labor intensity, improve product quality, save energy, and reduce Cost, some additives are often used in various processing processes, among which surfactants play a very important role.
” >1、Surface active agents and their properties
” >Surfactant It refers to a substance that can significantly reduce the surface tension of liquid or the interfacial tension of liquid-liquid. Their molecules are composed of polar hydrophilic groups and non-polar hydrophobic groups. Common hydrophilic groups include carboxyl, sulfate, and sulfonic acid groups, amine groups, quaternary ammonium groups, hydroxyl groups, etc.; hydrophobic groups are groups represented by long-chain alkanes and aromatic hydrocarbons.
” >Because they have both hydrophilic and lipophilic properties “Amphipathic” property, therefore during chemical cleaning, the surface (or interface) properties of the cleaning solution can be changed, making it have a lower surface tension. According to the difference in charge of the surface active part, the surfactant is Divided into anionic, cationic, nonionic and amphoteric types. Surfactants have the functions of wetting, foaming, solubilizing, Defoaming and other properties.
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” >Water-based cleaning agents are mostly based on nonionic surfactants and anionic surfactantsA mixture composed of a compound as the main body and a variety of auxiliary agents.The former has great decontamination ability and good Anti-rust and corrosion inhibition capabilities, the latter can improve and improve the overall performance of the cleaning agent,The cleaning mechanism is by means of The wetting, penetration, emulsification, solubilization, and dispersion of surfactants weaken the adhesion of oil stains on the metal surface, and then physical methods such as mechanical stirring, brushing, heating, and ultrasonic waves are used to separate the oil stains from the metal surface. It enters the lotion and is emulsified and dispersed.
” >Surfactants commonly used in metal cleaning include fatty alcohol polyethylene oxide ethers, alkylphenol polyethylene oxide ethers, and dodecyl benzene sulfonic acid Sodium, lauryl glycol amide, sodium methoxy fatty acid amido benzene sulfonate, etc..
” >Wang Yu et al. studied the use of bis-octyl polymers The cleaning performance of metal cleaning agents is based on two types of gemini surfactants: oxyethylene ether and dialkyl benzene disulfonate. The results show that this metal cleaning solution containing anionic/non-gemini surfactants has high surface activity, and there is a good synergistic effect between anionic/non-gemini surfactants.
” >(2) Application in metal phosphating treatment p>
” >Phosphating treatment is to treat metals with dilute solutions containing phosphoric acid, phosphates and other chemicals. The metal surface reacts with phosphoric acid and phosphate media in the above solution Chemical reaction, transforming into a complete insoluble metal phosphate layer with moderate corrosion protection. This phosphate conversion coating on metal has many uses , it can improve the bonding force and corrosion resistance between paint and metal; it can also be used as a carrier for anti-rust oil, a carrier for lubricants during metal cold working, and a lubricant for friction tables, etc..
” >In order to improve the phosphating film structure, improve the phosphating The phosphating solution also contains other additives, among which the functions of surfactants are as follows: It has the effect of emulsifying and solubilizing the oil stains adhered to the metal surface, and can prevent the reprecipitation of the dirt; making the solution moist , penetration, which is conducive to the contact between the phosphating liquid and the metal surface; reducing the surface tension of the liquid is conducive to the escape of hydrogen during the phosphating reaction, strengthening cathode depolarization, thereby accelerating the phosphating film formation process.
” >Surfactants commonly used in phosphating treatment are formed by the condensation of ethylene oxide and various hydrophobic hydrocarbon long chains, that is,Nonionic surfactants.
” >(3) Application in metal electroplating
” >In the electroplating process, in order to improve the performance of the electrolyte and improve the quality of the coating, it is often necessary to add some additives, among which surfactants are one of the main varieties. , bright, diffuse, change the physical properties of the coating, inhibit the escape of acid mist, etc..
” >The surfactants commonly used in electroplating include Pingpingjia ,OP emulsifier, sodium lauryl sulfate, sodium methylene bisnaphthalene sulfonate, fluorosurfactant, fatty acid polyethylene oxide ester, polyethylene oxide castor oil, etc. .
style: none; border: 0px; font-family: Microsoft Yahei;”>In order to improve the phosphating film structure, To improve the phosphating effect, the phosphating solution also contains other additives, among which the functions of surfactants are as follows: It has the effect of emulsifying and solubilizing the oil stains adhered to the metal surface, and can prevent the reprecipitation of the dirt; making the solution Produces wetting and penetration, which is conducive to the contact between the phosphating liquid and the metal surface; reducing the surface tension of the liquid is conducive to the escape of hydrogen during the phosphating reaction, strengthening cathode depolarization, thereby accelerating the phosphating film formation process .
” >Surfactants commonly used in phosphating treatment are formed by the condensation of ethylene oxide and various hydrophobic hydrocarbon long chains, that is,Nonionic surfactants.
” >(3) Application in metal electroplating
” >In the electroplating process, in order to improve the performance of the electrolyte and improve the quality of the coating, it is often necessary to add some additives, among which surfactants are one of the main varieties. , bright, diffuse, change the physical properties of the coating, inhibit the escape of acid mist, etc..
” >The surfactants commonly used in electroplating include Pingpingjia ,OP emulsifier, sodium lauryl sulfate, sodium methylene bisnaphthalene sulfonate, fluorosurfactant, fatty acid polyethylene oxide ester, polyethylene oxide castor oil, etc. .
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