Resin foam composition and foam, and wallpaper

A resin foam composition, comprising:

• a resin emulsion,
• cellulose nanofibers,
• a crosslinking agent for interfacial crosslinking between the resin and the cellulose nanofibers, and
• an organic solvent in an amount not larger than about 30% mass in 100 mass of the resin foam composition,
• wherein the cellulose nanofibers are modified with a carboxyl group and an amount of the carboxyl group is about 0.1-3.5 mmol/g,
• wherein an amount of the crosslinking agent is 0.01-30 parts by mass per 100 parts by mass of resin in the resin foam composition,
• wherein the crosslinking agent comprises at least one compound having a reactive functional group selected from the group consisting of a carbodiimide group, an oxazoline group, and an isocyanate group,
• wherein a foaming agent is present in an amount of not larger than about 30 parts by mass per 100 parts by mass of the resin, and the foaming agent is a thermally expandable microcapsule foaming agent,
• wherein an amount of the resin is 10 to 80 mass % when the resin foam composition is taken as 100 mass %, and
• wherein the amount of the cellulose nanofibers in the resin foam composition is about 0.2-50 parts by mass, per 100 parts.