Leather Chemicals

Leathers are made from animal hides or skins. These hides have to go through numerous processes before the product is finally become ready. In accordance of the process in which a hide supposed to go through, different chemicals are used. At an initial stage, the hide undergoes an under beamhouse and tannery processes. In these processes, several chemicals such as soda ash, adhesive tanning agents, agents, ammonium chloride, ammonium sulphate, biocides, caustic soda, chromium sulphate, degreasers, formic acid, fungicides, lime, low-sulphide unhairing agents, magnesium oxide, salt, sodium sulphide, sodium hydrosulphide, sodium metabisulphite, sodium formate, sulphuric acid, surfactants and swell regulating are used.

Furthermore, the growth of bacteria can harm the animal hides and in order to protect these hides and skins from such damages, different biocides are widely used. A wide range of hides are swelled with the help of lime and caustic soda and in these hides, the pH level is raised with the help of soda ash and magnesium oxide. In order to extinguish the hairs on hide, sodium sulphide and sodium hydro-sulphide are immensely used. Ammonium sulphate and ammonium chloride are used to remove lime from the hides or skins. Sodium metabisulphite prevents the formation of toxic hydrogen sulphide gas during deliming. It also acts as a bleaching agent.

Next comes the dye house process. Chemicals used in this process are chromium syntans, chromium sulphate, degreasers, dyeing auxiliaries, dyes, fat liquors, polymers, resins, surfactants/wetting agents, sodium formate, sodium bicarbonate and syntans.

In order to the remove fats or grease, degreasers are used. In the neutralization process pH is raised with the help of sodium formate and sodium bicarbonate. For improving softness of the final leather, chrome syntans and chromium sulphate are used. Softness, fullness and roundness like properties are due to the use of syntans. Fatliquors is the one of the crucial chemical to ensure extreme softness to the final leather. For providing a desired color to the raw leather, a wide range of dyes and dyeing auxiliaries are used.

Finally comes the finishing process. In finishing process, the chemicals that are generally used are acrylic resins, acrylic lacquers, butadiene resins, crosslinkers, defoamers, dullers, dyes, fillers, handle modifiers, nitrocellulose lacquers, pigments, polyurethane resins, polyurethane lacquers and viscosity modifiers.

Different chemicals give different properties in the leather. For example: pigments on hides are used for eleminating defects on the leather's surface, handle modifiers are used to give the leather surface a waxy or slippery feel, defoamers prevents bubbles from forming in the finish mixture, butadiene resins provides good coverage to the leather, acrylic resins is used to provide adhesion and water resistance and polyurethane resins provides good toughness and good lightfastness to the finish leather