Rubber-modified polyamide resin, epoxy resin composition and cured product thereof

A phenolic hydroxy group-containing rubber-modified polyamide resin obtained by reaction of (1) one or both kinds selected from the group consisting of a butadiene polymer which is terminated with a carboxy group at both ends and has a weight average molecular weight of 1,000 to 10,000 and an acrylonitrile-butadiene copolymer which is terminated with a carboxy group at both ends and has a weight average molecular weight of 1,000 to 10,000 with (2) a polyamide resin terminated with an amino group at both ends and having a structure represented by the following formula (A),

• wherein, m and n are average values and represent 0.01≦n/(m+n)≦0.30, m+n represents a positive number of 5 to 200, and Ar represents a group represented by the following formula (1)
• wherein, R1 is a hydrogen atom, a fluorine atom, a hydroxy group or a substituent having 1 to 6 carbon atoms which may contain O, S, P, F and Si, R2 represents a direct bond or a divalent linking group of 0 to 6 carbon atoms which may contain O, N, S, P, F, and Si, an b is an average substituent number and represents a positive number of 0 to 4,
• which has a phenolic hydroxy group-containing aromatic polyamide segment having a structure represented by the above formula (A) and a butadiene polymer or acrylonitrile-butadiene copolymer segment selected from the following formula (B-1) or (B-2)
• —(CH2—CH═CH—CH2)x— (B-1)
• —(CH2—CH═CH—CH2)y—(CH2—CH(CN))z— (B-2)
• wherein, each of x, y and z is an average value, x represents a positive number of 5 to 200, y and z represent 0<z/(y+z)<0.09, and also y+z is a positive number of 10 to 200, wherein the molar ratio of the repeating unit represented by the following formula (B-3)
• —(CH2—CH═CH—CH2)— (B-3)
• and the repeating unit represented by the following formula (B-4)
• —(CH2—CH(CN))— (B-4)
• is
• 0≦(B-4)/((B-3)+(B-4)<0.09.