At a given heat load,The temperature at which petroleum resin deforms. The softening point provides the viscosity index within the resin, which is controlled by the average molecular weight of the oligomer. The softening point of a resin is generally determined by its relative molecular weight and structure. The larger the relative molecular weight, the higher the specific gravity of the circular structure, and the higher the softening point of petroleum resin. The softening point of petroleum resin is about 40-50 ℃ higher than the glass transition temperature Tg, the Tg point of C5 petroleum resin is about 20 ℃ above, and the Tg point of NR is about -70 ℃. The significance of softening point for customers is that it reflects the solubility properties of polymers and helps customers obtain the most suitable product formula at the required usage temperature.
When the components of the resin contain highly polar functional groups or double or triple bonds, petroleum resins are prone to producing darker colors. Therefore, when the formula contains non hydrogenated hydrocarbon resin, natural rosin, terpene derivatives, and other highly polar raw materials, the color is usually darker than that of the formula containing hydrogenated components. There are double bonds in the molecular chain of petroleum resin, and yellow light can pass through, so it appears yellow. By hydrogenation, double bonds can be saturated, and petroleum resins appear as water white. When the resin reacts with oxygen in the air at high temperatures, it may darken the color of the resin, indicating a decrease in the initial properties of the product.
The significance of petroleum resin color for customers: the most important thing is the resin's ability to resist thermal yellowing and aging. Unsaturation refers to the measurement of the number of residual unreacted double bonds in the molecular structure of petroleum resin, expressed by bromine number or iodine number. High degree of unsaturation indicates that its weather resistance and heat resistance are poor, and it is easy to oxidize or form carbon; But degree of unsaturation is also easy to graft. The acid value represents the carboxylic acid content in the molecules of C5 petroleum resin and measures the scale of changes in the carboxyl compounds of petroleum resin after being placed in air. The presence of inorganic impurities in ash petroleum resin is not desired, as these impurities are residues that are not completely separated after neutralization or rust in storage tanks and pipelines.
