PURPOSE: To improve heat resistant ability, compression proof ability, impact resistance and make it free from halogenation by constituting the most external layer of a heat insulation pipe, on the external periphery of which air chambers are formed, of polyolefin resin composition to which a specified reactive compound is reacted, added and impregnated in fire resistant insulation pipe for cold and hot water.
CONSTITUTION: A plastic structural body 3 comprising the external periphery of a base pipe 2 formed with many independent air chamber (d) and foamed body 4 made of polyethylene or the like are coated as layered body beforehand. The external periphery is coated with envelope material comprising inorganic fire resistant agent 6, for example, polyolefin resin composition including aluminium hydroxide. To this polyolefin resin composition, reactive compound selected from carboxylic acid group, carboxylic ester group or monomer including acid anhydride group, monomer including epoxy group, monomer including hydroxyl group, monomer including amino group, alkanyl imino ether derivative, multifunctional monomer, unsaturated silane compound and unsaturated titanate compound, for example, acrylic acid glycidyl, etc., are reacted, added and impregnated.
KEZUKA KIYOHISA
KAWAMURA TSUTOMU
NIPPON PETROCHEMICALS CO LTD