Thermally expandable multilayer packing for building material

摘要

[Problem] To provide a thermally expandable multilayer packing for building material, said thermally expandable multilayer packing exhibiting excellent surface appearance and fire resistance and admitting of free control of functions such as water tightness, air tightness and mechanical strength. [Solution] A thermally expandable multilayer packing for building material, having protruding parts and a body part in the cross-sectional shape based a plane perpendicular to the longitudinal direction. The thermally expandable multilayer packing comprises both a thermally expandable resin composition layer and a thermoplastic resin composition layer as the essentials, wherein the thermally expandable resin composition forming the thermally expandable resin composition layer comprises 100 parts by weight of a resin component comprising a chlorinated polyvinyl chloride resin and/or an EPDM, 3 to 300 parts by weight of a thermally expandable graphite, 3 to 200 parts by weight of an inorganic filler and 20 to 200 parts by weight of a plasticizer. The thermally expandable resin composition layer and the thermoplastic resin composition layer are formed by simultaneous co-extrusion using the thermally expandable resin composition and the thermoplastic resin composition.