Resin composition, resin cured product, and liquid discharge head

A method for manufacturing a liquid discharge head including a discharge port member provided with a discharge port for discharging liquid, the method comprising:

• providing a layer of a photosensitive resin composition for forming the discharge port member on the substrate, the composition comprising:
• an epoxy resin (A) represented by Formula (1);
• an epoxy resin (B) having an epoxy equivalent of 220 or less and having twice or more epoxy groups in a molecule than epoxy groups of the epoxy resin (A);
• and
• a photocationic polymerization initiator (C), wherein:
• the epoxy resins (A) and (B) constitute main components of the photosensitive resin composition;
• and
• a weight of the epoxy resin (A) is 40% or more and a weight of the epoxy resin (B) is 30% or more with respect to a total weight of the epoxy resins (A) and (B),
• where:
• R represents a hydrogen atom, a methyl group, an ethyl group, a propyl group, or a t-butyl group;
• n represents an integer of 0 or more and 4 or less;
• and m represents an integer of 1 or more and 3 or less;
• and
• exposing a part of the layer and removing a part of the layer not exposed to form the discharge port.