Sound-proofing material and method for producing same

A sound-proofing material comprising a polyurethane foam including a double wall structure region composed of a first skin layer/a core layer/a second skin layer, wherein

• a density ratio of a first skin layer region A is 1.05 or more,
• a density ratio of a second skin layer region A is 1.05 or more, and an overall (OA) density is less than 130 kg/m3,
• where
• the “density ratio of a first skin layer region A” refers to a ratio (=ρs1/ρc) of a density (ρs1) of the first skin layer region A to a density (ρc) of a core layer region A,
• the “density ratio of a second skin layer region A” refers to a ratio (=ρs2/ρc) of a density (ρs2) of the second skin layer region A to the density (ρc) of the core layer region A,
• the “core layer region A” refers to a region of ±tA/2 from a center of the double wall structure region,
• the “first skin layer region A” refers to a region from a surface on a side of the first skin layer of the double wall structure region to a depth tA,
• the “second skin layer region A” refers to a region from a surface on a side of the second skin layer of the double wall structure region to the depth tA, and
• tA is 5.0 mm or t0×0.125 (t0 is a thickness of the double wall structure region).