- Hardness
- Thermoplasticity
- Color
- Heat Stability
- Clarity
- Chemical Reactivity
- Compatibility
- Solubility
- Oxidative Resistance
- Noncrystallinity
Additionally, rosins and their derivatives offer useful properties in numerous applications (including adhesives), providing specific adhesion, wetting characteristics to various substrates, and viscosity control.
A natural product, rosin is useful in food applications such as chewing gums and citrus beverages, or wherever stringent regulatory clearances are required.
Other application areas where rosin and rosin-based resins are used include:
- Cement and Asphalt
- Coatings and Sealants
- Emulsion Polymerization
- Surfactants
- Papermaking
- Rubber and Plastics
Rosin is a complex mixture of organic materials produced by a pine tree. Three forms of rosin are used commercially by Hercules worldwide: gum rosin, tall oil rosin, and wood rosin. These crude rosins are treated by chemical and physical means to produce refined rosins and darker, modified rosins. These are further modified, changing color, viscosity, hardness, oxidation resistance, and other properties to increase their usefulness.
One of the many modifications used by Hercules is hydrogenation. Rosin, by its nature, is very susceptsble to oxidation, forming products with undesirable properties, including darker color. The oxidation reaction takes place with the abietic-type resin acids, where oxygen reacts with the resin through a system of conjugated double bonds. Hydrogenation alters this double-bond structure, thus stabilizing the resin.
Hydrogebation can take place in varying degrees depending on the number of double bonds affected during the reaction. Hydrogenation improves the initial color and color stability of the resin through hydrogenation of color bodies. Like-wise, it significantly decreases the susceptibility of the resin to oxidative attack, as seen through the Sealed Vial Oxygen Uptake test. Increasing the levelof hydrogenation not only im-proves the oxidative stability of the resin, but also changes the compatibility of the resin and its derivatives in various polymer systems.
Hydrogenated rosi and rosin esters have acquired numerous Food & Drug Administration (FDA) and other regulatory clearances in a wide range of applications, including chewing gum and adhesives.
