Waxes are organic compounds that are solid and malleable at ambient temperatures, melting into low-viscosity liquids when heated. They are valued for their water-repellent, lubricating, and protective coating properties. This article explores the various methods through which different types of wax are produced, from natural biological processes to industrial chemical synthesis.
Waxes Originating from Living Organisms
Beeswax is produced by worker bees within a hive. Young worker bees possess specialized glands on their abdomens that secrete liquid wax, which hardens into small flakes upon exposure to air. These bees then chew the wax flakes, mixing them with saliva, to construct the hexagonal cells of their honeycomb, which serves as storage for honey, pollen, and as a nursery for young bees. Beekeepers harvest the honeycomb, and the beeswax is subsequently rendered by melting it down and filtering out impurities like honey, propolis, and other debris, yielding purified wax.
Plants produce various waxes as protective coatings on their leaves, stems, and fruits. These waxy layers help to minimize water loss through transpiration, protect against insect damage, and resist fungal and bacterial infections. Carnauba wax, derived from the leaves of the Copernicia prunifera palm native to northeastern Brazil, forms a powdery coating. This coating is scraped off, dried, and processed, often through boiling and filtering, to purify it.
Candelilla wax originates from the Euphorbia antisyphilitica plant, a shrub found in arid regions of Mexico and the southwestern United States. The wax is typically obtained by boiling the plant’s stems in acidic water, causing it to float to the surface for skimming and further processing.
Waxes Derived from Fossil Fuels
Paraffin wax is produced during the refining of crude oil. The process begins with fractional distillation, where crude oil is heated and separated into different components, or fractions, based on their boiling points. Lighter fractions like gasoline and kerosene vaporize at lower temperatures, while heavier fractions remain as liquids.
Paraffin wax is obtained from the heavier lubricating oil fractions that emerge from this distillation process. These fractions contain a mixture of oil and wax, known as “slack wax.” To isolate the wax, slack wax undergoes chilling, solidifying the wax components for separation from the oil. This chilled mixture is then filtered, often using rotary vacuum filters, to remove the oil, a process called deoiling. The resulting solid paraffin wax is further purified through hydrotreating or clay treatment to remove impurities and improve its color and odor.
Microcrystalline wax originates from the heavier residual fractions left after more volatile crude oil components are removed. Unlike paraffin wax, which has a larger, more crystalline structure, microcrystalline wax is characterized by its finer, less distinct crystal structure and higher branched hydrocarbon content. This difference gives microcrystalline waxes distinct properties, such as greater flexibility and adhesion compared to paraffin wax.
Waxes Created Through Chemical Processes
Some waxes are manufactured through chemical synthesis in industrial settings. These synthetic waxes are designed to possess specific properties for diverse applications. Polyethylene waxes, for example, are produced through the polymerization of ethylene monomers. This process involves chemically linking smaller ethylene molecules to form long polymer chains.
The properties of polyethylene waxes, such as melting point, hardness, and viscosity, can be precisely controlled by adjusting polymerization conditions, including temperature, pressure, and catalyst choice. High-density polyethylene waxes, for instance, are typically produced to have a higher melting point and greater hardness, while low-density versions are softer. These synthetic waxes offer consistent quality and tailored characteristics, finding use in industries from polishes and coatings to adhesives and plastics due to their customizable attributes.