Hydrocarbon Resins
Properties and Applications
Hydrocarbon resins are amorphous polymers produced mainly from by-products of naphtha crackers. These resins have typically a low to medium molecular weight ranging from about 400 to 5000 g/mol. The three main types are C5 aliphatic, C9 aromatic, and DCPD cycloaliphatic resins. Their composition and properties depend on the feedstock (coal tar, crude oil).
C5 aliphatic hydrocarbon resins are made from C5 piperylene and its derivatives which are polymerized to oligomeric resins. Due to their aliphatic nature, they are fully compatible with natural rubber, most olefins (LDPE) and many synthetic elastomers of low polarity. They are available in a wide range of molecular weights (MW) and softening points (solid grades 85 - 115°C and liquid grades 5 - 10°C).
C9 aromatic hydrocarbon resins are made from C9 aromatic feedstock. The most important base monomers are indene, methyindenes, dicyclopentadiene, vinyl benzene and vinyl toluene. C9 resins are available in a wide range of softening points. Compared to C5 resins, they have a much higher melt viscosity, are of darker color and have a higher softening point ranging from about 100 to 150°C.
Hydrocarbon resins are sometimes hydrogenated to reduce discoloration and to improve their heat and UV stability.
However, these resins are noticeably more expensive and thus are
only used if good color stability and improved performance is
required.
Hydrocarbon resins are used as tackifiers, performance modifiers, and homogenizing agents in a large number of products including hotmelts, tapes, sealants, labels, paints and printing inks. One of the most important applications is adhesives and tapes. They enhance tack and peel adhesion, and lower the melt viscosity and softening point of the base polymer. When added to paints and inks, they improve pigment wetting, adhesion, gloss, hardness and mildew and water resistance.