| 摘要 |
<p>PURPOSE: To reduce occurrence of compression deformation during discharge to a vacuum and to reduce vacuum heat conductivity by a method wherein an average length of inorganic fibers is decreased to a value lower than a specified value, and control is effected so that the orientation direction of the inorganic fiber is extended vertically to a heat transfer direction. CONSTITUTION: Inorganic fibers having a average fiber length of 1mm or less forms a main component and the inorganic fibers are oriented in a direction vertically to the direction of heat conduction. It is preferable that the average length of the inorganic fibers is in a range of 0.1-1mm. When the average fiber length is 0.1mm or less, strength of a heat insulation material itself is low and density is too high, orientation of fibers is not controllable and at random. When the average fiber length exceeds 1mm, occurrence of compression deformation during discharge to a vacuum is not reduced. Further, the average fiber diameter of the inorganic fibers is preferably 0.5-3μm. the inorganic fiber having an average fiber diameter of 0.5μm or less is high in a manufacturing cost and has no high general purpose usability and when the average fiber diameter exceeds 3μm, a recess is increased during discharge of a vacuum.</p> |
