Abstract: A process for preparing a hydrocarbon resin which comprises copolymerizing (A) a hydrocarbon fraction boiling within the range of 130.degree. to 300.degree. C. obtained by cracking, reforming and/or refining petroleum with (B) dicyclopentadiene in the presence of a Friedel-Crafts catalyst in a proportion such that the resulting hydrocarbon resin contains, based on the total weight thereof, 20 to 80% of a unit derived from the dicyclopentadiene (B).A hydrocarbon resin having a number average molecular weight of 300 to 2500, a softening point of 40.degree. to 180.degree. C., a bromine number of 5 to 100 g/100 g, and a Gardner color hue of 5 to 17, prepared by the above process. This hydrocarbon resin is useful as an adhesive component of pressure-sensitive adhesives and hot-melt composition.

Abstract: A process for preparing resins for use in printing inks, which comprises co-polymerizing at least 50% by weight of dicyclopentadiene and not more than 50% by weight of another cationically polymerizable monomer in the presence of a Friedel-Crafts polymerization catalyst, adding 1 to 20% by weight, based on the weight of the resulting co-polymer, of an .alpha.,.beta.-unsaturated carboxylic acid or its anhydride to the resulting copolymer, and then esterifying the resulting adduct at last partially with a polyhydric alcohol.