As discussed in the section on
C5, Aliphatic Resins, the feedstocks for hydrocarbon resins are produced via cracking of naphtha. Basic C9, aromatic resins are produced from C9 resin oil that contains various monomers as illustrated in Figure 1.
Figure 1: C9 Resin Oil Composition
A cationic polymerization reaction converts the liquid feed to a hard resin as seen in Figure 2.
Figure 2: C9 Resin Oil Polymerization
The aromatic characteristics of the feedstocks are preserved in the final resin polymer so the molecular weight and solubility properties of C9 resins are considerably different from those of C5, aliphatic tackifiers. Since C9 resin oil is a relatively unrefined material, its polymerization leads to much darker resins than other hydrocarbon resins. Due to their aromatic structure, C9 resins are more compatible with polar elastomers than C5 resins. They are most commonly used in systems based on styrene butadiene rubber, styrene-butadiene-styrene block copolymers, polychloroprene rubber, ethylene vinyl acetate copolymers with high levels of vinyl acetate (>28%), chlorinated paraffins, paints, and concrete curing compounds.
Table 1: Property Ranges of C9, Aromatic Hydrocarbon Resins
|Ring and ball softening point, °C||100–142|
|Gardner color (50% in toluene)||6–12|
|Glass transition temperature, °C||40–85|
|MMAP cloud point, °C||2–45|
|DACP cloud point, °C||35–100|
The C9, aromatic hydrocarbon resins produced by Eastman Chemical Company are: