Resin composition for sealing electronic device, and electronic device

A resin composition for sealing an electronic device, the resin composition comprising:

• (A) a polybutadiene polymer represented by formula (1) and having a (meth)acryloyl group at a terminal end thereof;
• (B) a photopolymerization initiator;
• (C) a reactive diluent, wherein a mass ratio between the component (A) and the component (C), (A):(C), is 5:95 to 50:50;
• and
• (D) a hydrocarbon compound having a number average molecular weight of less than 50,000, wherein a mass ratio of the sum of the component (A) and the component (C) to the component (D), [(A)+(C)]:(D), is 20:80 to 70:30;
• and
• wherein the resin composition does not include a thermoplastic resin having a mass average molecular weight of 50,000 or more:
• wherein R1 and R2 each independently represent a hydroxyl group or H2C═C(R7)—COO— provided that R1 and R2 do not represent hydroxyl groups at the same time;
• R3 and R4 each independently represent a substituted or unsubstituted divalent organic group having 1 to 16 carbon atoms and at least one of R3 and R4 comprises a group of formula (2);
• R5, R6 and R7 each independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms;
• l and m each independently represent 0 or 1;
• n represents an integer from 15 to 150;
• and the ratio x:y is such that x:y=0 to 100:100 to 0