Addition-curable silicone resin composition, addition-curable silicone resin cured product, and optical semiconductor element sealed body

The purpose of the present invention is to provide an addition-curable silicone resin composition having excellent interface adhesion and transparency. The purpose of the present invention is also to provide an addition-curable silicone resin cured product comprising said addition-curable silicone resin composition and to provide an optical semiconductor element sealed body. This addition-curable silicone resin composition contains an addition-curable silicone resin mixture and an adhesiveness-imparting agent. The adhesiveness-imparting agent contains a compound having a structural unit indicated by formula (1-3) and/or a structural unit indicated by formula (1-4), between a structural unit indicated by formula (1-1) and a structural unit indicated by formula (1-2). Each R 1a in formula (1-1) and formula (1-2) independently indicates a C1-18 alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, a C2-9 alkenyl group, or a C1-4 alkoxy group. Each R 1b in formula (1-3) and formula (1-4) independently indicates a C1-18 alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, a C2-9 alkenyl group, or a C1-4 alkoxy group. m in formula (1-3) indicates an integer 1-50 and n in formula (1-4) indicates an integer 1-1,500. Each A in formulas (1-1)-(1-3) independently indicates a C1-18 alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, a C2-9 alkenyl group, a C1-4 alkoxy group, or a group indicated by formula (2). However, at least one A in formulas (1-1)-(1-3) indicates a group indicated by formula (2). R 2a in formula (2) indicates a C1-8 alkylene group having some carbon atoms, excluding carbon atoms bonded to silicon atoms, substitutable by oxygen atoms. Each R 2b independently indicates a C1-3 alkylene group and each R 3 independently indicates a C1-18 alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, a group including a sulfonyl group, an acyl group, a (meth) acryloyl oxyalkl group, or a silyl group. In formula (2), x is an integer 0-2 and Y is an oxygen atom or NH.