The double bond in the acid structure of rosin resin is one of the reactive active centers. Reactions based on double bonds, especially conjugated double bonds, are much more complex than those based on carboxyl groups, and the number of reaction products is also much higher. The so-called modification of rosin is essentially based on such reactions, by introducing appropriate functional groups through double bonds in resin acids to achieve the purpose of modification.
Hydrogenated rosin
The conjugated double bonds of abietic resin acids in hydrogenated rosin series are partially or completely saturated with hydrogen gas under the action of a catalyst at a certain temperature and pressure.
Rosin partially saturated with hydrogen is called dihydrorosin, commonly known as hydrogenated rosin. Rosin that is completely saturated with hydrogen is called tetrahydrorosin, also known as fully hydrogenated rosin.
Disproportionated rosin
When rosin was used as the emulsifier of Styrene-butadiene, it was found that dehydroabietic acid and dihydroabietic acid accelerated the polymerization of styrene butadiene, while the presence of conjugated double bond resin acid significantly slowed the polymerization of butadiene and styrene, while the presence of non conjugated double bond resin acid had little effect.
In ordinary resin rosin, there are more than 70% conjugated double bond resin acids.
Polymerized rosin
Polymerized rosin is one of the important varieties in rosin modified products. It has the characteristics of high softening point, light color, non crystallization, excellent oxygen resistance, higher viscosity in organic solvents, and low acid value.
Due to the presence of conjugated double bonds in abietic resin acids in rosin, rosin polymerizes into dimers of abietic resin acids. Polymerization usually occurs under the action of acidic catalysts to produce polymerized rosin.
Malay rosin
Malay rosin is a highly efficient modified rosin. It is a product obtained by a certain chemical reaction between rosin and maleic anhydride. This product was made in the 1930s and gradually applied in industries such as paper, paint, and ink.