hydrogenated resins are amorphous thermoplastic polymers produced by polymerization of unsaturated hydrogenated resin. The feedstock are various by-products of naphtha crackers.1 These resins have typically a low molecular weight ranging from about 400 to 5000 g/mol. The three main types are C5 aliphatic, C9 aromatic, and DCPD cycloaliphatic resins. They are sometimes hydrogenated to reduce discoloration and to improve their heat and UV stability.
Aliphatic hydrogenated resins (C5 Hydrocarbon Resins) are made from C5 piperylene and its derivatives. The most important ones are cis/trans 1,3-pentadienes, 2-methyl-2-butene, cyclopentene, cyclopentadiene, and dicyclopentadiene (see below). These monomers are polymerized to oligomeric resins with low to high softening point using Lewis acid catalysts. C5 resins are aliphatic in nature and are, therefore, 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) and provide outstanding tack. They also have a light yellow to light brown color and possess excellent heat stability.
Aromatic hydrogenated resins (C9 Petroleum Resins) are made from C9 aromatic hydrogenated resin. Their composition depends on the hydrocarbon feedstock (coal tar, crude oil). The most important base monomers are indene, methyindenes, dicyclopentadiene, styrene, alpha-methylstyrene and various vinyl toluenes (see below). These 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 (dark yellow to brown)2 and have higher softening point ranging from about 100 to 150°C.3 C9 resins are very versatile resins that are compatible with many polymers.
Hydrogenated C5/C9 resins and resin blends are also commercially
available. These resins are often colorless and have improved heat and
color stability. However, they are also noticeably more expensive and
only used if superior heat and color stability is of concern.
hydrogenated resins are used as tackifiers, performance modifiers and homogenizing agents. They are extensively used in the manufacture of rubbers, coatings, printing inks, and adhesives. The largest market for hydrogenated resins are hot melts, PSA tapes and labels. They are important ingredients in many rubber adhesive formulations, particularly synthetic rubbers that are less tacky than natural rubber. They improve tack, peel strength, and increase the glass transition temperature, which in turn improves shear strength. In paints, they provide superior pigment wetting, enhanced adhesion, gloss, and film hardness. They also improve flow and leveling, reduce VOCs and provide improved mildew and water resistance.