To obtain the subject oligomer having excellent moldability, low hygroscopicity, high heat resistance, adhesivity to different materials and electrical insulating properties by making the oligomer include a specific structural unit in a specified ratio.
This oligomer comprises structural units of formula I to formula II (R1 and R2 are each H or a 1-12C hydrocarbon) in the molar ratio of the structural unit of formula I/formula II of 100/0 to 0/100 and contains a structural unit of formula III at least at one end. The objective oligomer having 200-5,000 number-average molecular weight is obtained by polymerizing 0-50 mol% of a styrene with 20-90 mol% of an indene and 10-30 mol% of a thiophenol or its thioether. Preferably the polymerization is carried out in the presence of an acid catalyst (e.g. boron trifluoride dimethyl ether complex) to give an oligomer having 50-200°C softening point.
KAJI MASASHI
YONEKURA KIYOKAZU
YANO HIROYUKI
KATAYAMA HISASHI
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