Epoxy resin composition, prepreg, resin-coated metal foil, resin sheet, laminate and multilayer board

An epoxy resin composition containing:

• a polyfunctional epoxy resin (A);
• a polyphenylene ether compound (B);
• a phosphorus-modified curing agent (C);
• and
• a component other than (A), (B) and (C), wherein:
• the polyfunctional epoxy resin (A) includes an average of 3 or more epoxy groups per molecule,
• the polyphenylene ether compound (B) includes an epoxy resin (B2) obtained by reacting a polyphenylene ether (B1) with an epoxy resin (D), the epoxy resin (D) having an average of 2.3 or fewer epoxy groups per molecule, and the polyphenylene ether (B1) having a number-average molecular weight of 500 to 2000 and an average of 1.0 to 3.0 hydroxyl group per molecule,
• at least one selected the group consisting of the polyfunctional epoxy resin (A), the epoxy resin (D), and the component other than the (A), (B) and (C) includes a phosphorus-modified epoxy resin (P),
• the phosphorus content is 1.5 to 4.5 mass % as a percentage of resin solids in the epoxy resin composition,
• the phosphorus-modified curing agent (C) is a resultant in a reaction between a first compound and an organic phosphorus second compound of the following Formula (I);
• the first compound is a resultant in an etherification between at least one monomer alcohol and a condensation product,
• the condensation product is a resultant in a condensation between formaldehyde and a phenol compound,
• wherein each R independently represents hydrogen or a C1-6 hydrocarbon group, and n is an integer from 0 to 4,
• a solids content of the phosphorus-modified curing agent (C) falls within a range of 3.9 to 43 mass % with respect to solids mass of the polyfunctional epoxy resin (A) and the polyphenylene ether compound (B), and
• the polyfunctional epoxy resin (A), the polyphenylene ether compound (B) and the phosphorus-modified epoxy resin (P) are miscible.