Foamable resin composition

A foamable resin composition, comprising:

• a urethane (meth) acrylate oligomer having an inclusion quantity from 20 to 90 parts by weight;
• a photoinitiator having an inclusion quantity from 0.1 to 10 parts by weight;
• a heat-expandable microcapsule having an inclusion quantity from 1 to 25 parts by weight;
• and
• a photopolymerizable monomer having an inclusion quantity from 10 to 45 parts by weight, wherein:
• the photopolymerizable monomer comprises at least one compound with chemical formula R—Xa, having a group of a reactive functional group X and a non-reactive functional group R,
• the non-reactive functional group R is selected from a group consisting of a small molecule group, a group with steric hindrance, a group with side reaction sites, and a long chain group,
• a weight ratio of the urethane (meth) acrylate oligomer and the photopolymerizable monomer in the foamable resin composition is from 1.5:1 to 2.5:1, and
• the photopolymerizable monomer comprises:
• a compound with chemical formula (1),
• wherein R1 is a straight-chain or branched-chain alkyl of C1-C18, a substituted cycloalkyl or non-substituted cycloalkyl, or a substituted aryl or non-substituted aryl, and R2 is hydrogen or methyl,
• at least one of a compound with chemical formula (2) or (3)
• wherein R3 is hydrogen or methyl and n is any integer from 3 to 12,
• wherein Y is a straight-chain or branched-chain alkylene of C1-C18, or a substituted or non-substituted cycloalkylene, and R4 is hydrogen or methyl, and
• at least one of a compound with chemical formula (4) or (5),
• wherein i+j+k=15, and R5 is hydrogen or methyl;
• wherein R6 is hydrogen or methyl.