RUBBER COMPOSITION FOR PRODUCING FOAM HAVING HIGH FOAM RATIO, HIGH FOAM RATIO FOAM, TIRE, ACOUSTIC MEMBER, SEALING MATERIAL, HOSE, TAPE, WIRE COATING, HEAT INSULATION MATERIAL, FOAM RATIO IMPROVER FOR RUBBER, METHOD FOR IMPROVING FOAM RATIO, AND METHOD FOR PRODUCING HIGH FOAM RATIO FOAM

Provided are a rubber composition for producing a foam having a high expansion ratio, a foam having a high expansion ratio, a tire, an acoustic member, a sealing material, a hose, a belt, a wire coating, a heat insulating material, a foam ratio improver for rubber, a method for improving the expansion ratio of a foam, and a method for producing a foam having a high expansion ratio. A rubber composition for producing a foam having a high expansion ratio, the rubber composition comprising the following components (a), (b), (c), and (d). (a) a rubber component, (b) a chemical foaming agent, (c) a compound represented by formula (1) or a salt thereof, and (d) at least one selected from the group consisting of vulcanizing agents and cross-linking agents. In the formula, R1 represents a hydrogen atom, an alkyl group or an aralkyl group, R2, R3 and R4 may be the same or different and represent a hydrogen atom, an alkyl group, an aralkyl group or an aryl group, and each of these groups may further have one or more su