Masking agents and oil from Curtin7 February 2002
Spanish leather chemical makers Curtin have introduced two new basifying masking agents for chrome tanning and a fatliquor for garment leathers. Adutan MB is a basifying and masking agent made from organo-metallic compounds, which provide a slow alkaline basification and strong masking properties. The fine white powder provides good fixation and exhaustion of the chrome. The alkaline properties of Adutan MB are slow and progressive allowing a gentle pH evolution during the chrome tanning process after Adutan MB has been added. Increasing the temperature during basification completes the reaction. The second function of Adutan MB is to act as a masking agent. In practice, the use of Adutan MB provides the leather with a fine open grain, good fullness and level colour. The fixation of the chrome onto the leather is very uniform and can even be used with heavy cowhide without splitting, (grain, intermediate layers and flesh). The product should be added in the tanning bath and the normal offer is about 20% based on the amount of chrome sulfate in the tanning bath, however the exact quantity should be determined according to the different variables of each tannery such as the volume of the pickle bath, pH and chrome basicity etc. Adutan OM is similar to Adutan MB and is a basifying masking agent added during chrome tanning. The white/yellowish powder is based upon an organo-metallic compound with alkaline properties and a strong masking power. Adutan OM is a balanced blend of several products, which produce several effects on the chrome complex. The offer and reactivity of Adutan OM is the same as Adutan MB. The product is always applied during the chrome-tannage bath; it can be used in a single addition, although it is recommended to add it in two offers. The addition is about 10%, based on the amount of chrome sulfate, although the exact quantity should be determined according to the different variables in each tannery such as the pickle bath volume, pH and chrome basicity etc. It is a suitable product to be used when a long bath of water is needed for the chrome tanning process, (sheepskin, goatskin, crossbreeds etc). The product can also be used in a short bath tanning process. Aduvax E-325 is a special fatliquor designed for garment leathers. The white liquid emulsion is a preparation based on a surface-active agent and synthetic oils and it has the following physical properties: Water content (%): 51-55 Solid content (%): 45-49 Anionic matter (%SO3): 0.9-1.6 pH emulsion (1:10): 6.0-8.0 Emulsion stability: stable milky solution Emulsion stability with Cr III: stable Emulsion stability in pickle: stable Because this is an emulsion based product, it is necessary to agitate and to mix before using. It is an entirely synthetic lubricant with special properties. It is completely non-oxidisable and provides a particularly soft handle or feel. Aduvax E-325 is as stable as an emulsion and can be used during the tanning or retanning process. It also has a very strong affinity with the leather fibre structure and has good penetration into the leather. Aduvax E-325 can also be used on woolskins such as shearlings etc as it is possible to alleviate the problems of cleaning the wool or hair, thus being an ideal fatliquor for wool or hair-on products. The hydrophilic character of skins can also be enhanced using Aduvax E-325.