The main performance indexes of paraffin wax are melting point, oil content, and stability.
Paraffin wax is a mixture of hydrocarbons, so it does not have a strict melting point like pure compounds. The so-called melting point of paraffin wax refers to the temperature of the first stagnation period on the cooling curve when the melted paraffin wax sample is cooled under specified conditions. All kinds of wax products require paraffin wax to have good temperature resistance, that is, it does not melt or soften and deform at a specific temperature. Commercial paraffin wax is required to have a series of different melting points according to the differences of using conditions, areas, seasons, and using environment. The main factor affecting the melting point of paraffin wax is the weight of the selected raw material fraction. The melting point of paraffin wax removed from the heavier fraction is higher. In addition, the oil content also has a great influence on the melting point of paraffin wax. The more oil in paraffin wax, the lower the melting point.
Oil content refers to the amount of low melting point hydrocarbons contained in paraffin wax. High oil content will not only affect the chroma and storage stability of paraffin wax but also reduce its hardness. Therefore, the oil-bearing wax paste removed from the vacuum distillate needs to be deoiled by the sweating method or solvent method to reduce its oil content. However, most paraffin products need to contain a small amount of oil, which is beneficial to improve the luster and demoulding performance of the products.
In the process of modeling or coating, paraffin products are in a hot-melt state for a long time and in contact with air. If the stability is not good, it is easy to oxidize and deteriorate, darken the color, and even send out the odor. In addition, paraffin wax will turn yellow under light conditions. Therefore, paraffin wax is required to have good thermal stability, oxidation stability, and light stability. The main factors affecting the stability of paraffin wax are the trace of non-hydrocarbon compounds and polycyclic aromatic hydrocarbons contained in paraffin wax. In order to improve the stability of paraffin wax, it is necessary to deeply refine paraffin wax to remove these impurities.