The washing effect of surfactants - dry cleaning

The washing effect of surfactants is the basic characteristic of the most practical use of surfactants. It involves the daily life of thousands of families. And in all walks of life and various industrial production has also been more and more applied.

Dry cleaning is a method of washing in organic solvents, which uses the solubility of solvents and the solubility of surfactants to remove dirt on the surface of the fabric. Its advantage is that it can prevent the irreversible shrinkage of wool and silk fabrics caused by washing, and the problems of clothing deformation and poor hand feel.

The dirt on the fabric is roughly divided into three types: oil-soluble, water-soluble and oil-water insoluble.

Oil soluble dirt can be removed directly with organic solvents. The oil agent that can be used for washing solvent is mainly light petroleum hydrocarbons, and the main component is the aliphatic group based on n-decane, such as l, 3-diethylcyclohexane, aliphatic group and 1, 2, 4-trimethylbenzene aromatic group. In addition, there are carbon tetrachloride, trichloroethylene, tetrachloroethylene and so on.

In order to remove water-soluble or hydrophilic dirt, it is also necessary to add a small amount of water and surfactants in the system, and the addition of surfactants can prevent the redeposition of solid dirt in the solvent. The dispersion stability and suspension of dirt in organic media no longer depend on the electrorepulsion between particles, but may depend on the adsorption of surfactants at the solid-liquid interface.

In the organic medium, the surfactant is adsorbed on the solid surface with polar basis, and the oil-hydrophilic hydrocarbon chain is adsorbed on the solid-liquid interface towards the adsorption state of the organic solvent. In this way, a layer of hydrocarbon chain solvation film can be formed on the solid dirt surface to form a space barrier to prevent dirt accumulation or redeposition on the fabric surface. The presence of a small amount of water can hydrate the particle and textile surface, so that it is easy to interact with the polar group of the surfactant, which is conducive to the adsorption of the surfactant on the solid surface (especially the general polar surface). This is conducive to improving washing efficiency. In addition, when surfactants form reverse micelles in organic solvents, a small amount of water and its water-soluble dirt are often dissolved in the reverse micelle at the same time.

Surfactants for dry cleaning should have the following conditions:

(1) It can be dissolved in washing solvents, and after forming reverse micelles, it should have enough capacity to add dissolved water;

② Can disperse solid dirt well, so that dirt has good suspension stability in organic solvents;

③ The residual adsorption amount on the wash and filter is small;

No odor, no adverse effect on washing, no corrosion to metal, etc.

Surfactants used for dry cleaning should be readily soluble in organic media. Commonly used are:

① Anionic surfactants such as petroleum sulfonate, sodium alkyl benzene sulfonate (or amine salt), sodium succinate sulfonate;

② Non-ionic surfactants such as polyoxyethylene alkyl alcohol ether, polyoxyethylene alkyl phenol, polyoxyethylene alkyl amide, etc.