Montan wax
Contents
Description
Montan wax is a hard, brittle, lustrous wax extracted from lignites, principally in Central Europe and also mined in Australia, New Zealand, Czechoslovakia, Russia, Great Britain and in the United States. The coal is granulated, dried and solvent extracted to remove the wax. The crude wax is usually further processed to produce an acceptable market product. One type of refining is by vacuum distillation, using steam and producing the so-called "double-refined" montan wax. In a second a more important refining process, the wax may be deresinified by solvent processing, and then treated by chromic acid oxidation. The crude wax is dark brown and the refined wax of a yellowish color. The so-called white montan wax is a mixture of refined montan wax with paraffin wax. Depending on the geographical occurrence, the resin content of the wax varies. For example, the German deposits are noted for their relatively low resin content, thus yielding a satisfactory product more economically[1].
Properties[2]
| Melting Point | 72 -92 ºC |
| Specific Gravity | 1.00 |
| Acid Number | 15 - 85 |
| Saponification Number | 58 - 89 |
| Unsaponifiables | 35 - 45% |
| Iodine Number | 7.75 |
| Acetyl Number | 11.2 |
| Color | tan, brown |
| Dielectric Constant | 2 - 68 |
| Effective A.C. Conductivity | 25 -55 |
| Volume Resistivity | 270 - 630 |
Solubility
Montan wax is soluble in: benzol, carbon tetrachloride, chloroform, dichloroethylene, isopropyl ether, naphtha, tetralin, toluol, trichloroethylene, turpentine, xylol.
Montan wax solutions set more slowly than carnauba wax solutions and, therefore, should be filled into containers at a lower temperature. Pure montan wax can scarcely be scratched by the fingernail. It breaks with a conchoidal fracture. It is a good solvent (when melted) for basic dyes and shows good wetting and flow in oil solutions. It is the hardest of the natural nonvegetable waxes and is fairly resistant to oxidation.
The bleached or highly refined wax loses some of the listed characteristics, becoming softer and less emulsifiable[3].
Uses
It can be used in place of carnauba wax in many compositions because of its hardness, toughness, high melting point and emulsifiability; polish, rubber, printing-ink, electrical insulating compositions, leather finishes and dressings, carbon papers, grease, phonograph records, waterproofing[4].
Comparison of the properties of different waxes
| German Montan Wax |
Devon Lignite Wax |
English Peat Wax |
Scottish Peat Wax | |
|---|---|---|---|---|
| Melting Point ºC | 74 - 82 | 73 - 83 | 63 -68 | 64 - 73 |
| Acid Value | 33 | 30 | 50 | 48 |
| Saponification Value | 76 | 75 | 119 | 113 |
| Ester Value | 43 | 45 | 69 | 65 |
| Resin Content, % | 14 | 40 | - | 23 |
| Specific Gravity at 20ºC | 1.05 | 1.04 | 1.03 | - |