1、 Principle of action
The decontamination effect of water-based cleaning agent is realized by the wettability, permeability, emulsification, dispersion and solubilization of surfactants.
1. The wetting of detergent solution on the washed substrate and dirt and the penetration between the two;
2. The surfactant in the cleaning agent emulsifies, solubilizes and disperses oily dirt, separates the dirt from the solid surface, and disperses or emulsifies in the washing medium (usually water);
3. Prevent emulsified oily dirt and dispersed solid dirt from re depositing on the substrate surface. The washing process is a reversible process, and the dirt dispersed and suspended in the medium may also be redeposited on the solid surface, which is called dirt redeposition.
The cleaning effect will be greatly improved if a certain amount of mechanical force is applied in the above process.
2、 Selection of surfactants
Due to the difference of cleaning base materials, and choose the appropriate cleaning agent, cleaning environment is divided into: neutral, acidic, alkaline, the correct selection of surfactants will play an important role.
1. During pickling
In order to improve the pickling effect, that is, to accelerate the dissolution of oxide layer, delay the corrosion of acid on the matrix and inhibit the diffusion of hydrogen atom to the matrix, a small amount of surfactant is often added into the metal pickling solution, because the added surfactant will form a thin film on the metal surface and play a certain role in corrosion inhibition.
2. During alkaline washing
The main function of surfactant is to reduce surface tension, emulsify and disperse dirt, so as to significantly improve cleaning efficiency.
Nonionic surfactants (such as alkyl phenol polyoxyethylene ether, polyether, etc.) have good wetting and permeability.
1. Adding a small amount of surfactant can reduce the surface tension between the substrate and the liquid surface, and improve the permeability, so that the alkali liquor can better contact with the oil, form saponification reaction, and remove part of the grease.
2. The addition of surfactant can increase the emulsification and dispersion of oil.
3. In the process of solvent cleaning. The main surfactants used are ethylene oxide adducts of esters, ethers and amines or their mixtures, and the mixtures of nonionic and anionic surfactants can also be used.
The selection of surfactant depends on the type of solvent and the type of detergent emulsion to be prepared. In addition, some cosolvent should be added to the solvent based cleaning agent to improve the solubility of the solvent (such as higher alcohols, glycol, glycol derivatives, etc.)