VACUUM HEAT INSULATION MATERIAL

PROBLEM TO BE SOLVED: To provide a vacuum heat insulation material with high uniformity in heat insulation characteristics, easily manufacturable by a normal paper making device and method, having a structure not having particular orientation in fiber orientation in a sheet horizontal direction, and providing efficient removal of a very small amount of adsorbed moisture on an inorganic fiber surface, in regard to a vacuum heat insulation material using multiple layers of wet type papermaking sheets mainly composed of inorganic fiber with very small diameters as a vacuum heat insulation material core material. SOLUTION: The vacuum heat insulation material is composed by using plurally laminated inorganic sheets formed by carrying out wet type paper making on mainly inorganic fiber with an average fiber diameter of 4 μm or less. It is characterized by that a percentage content of particulate matter with a particle size of 30 μm or more and fibrous matter with a diameter of 10 μm or more in the inorganic fiber is 0.1 wt.% or less, thickness of the inorganic fiber sheet is 0.2 mm or less, and the inorganic fiber in the core material is arranged in a vertical direction with respect to a laminated direction of the inorganic fiber. COPYRIGHT: (C)2007,JPO&INPIT