| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve heat insulating performance without increase in solid heat conductivity by mixing powder with a grain size within one specific range and powder with a grain size within another specific range together for using the mixture as a core material for a vacuum heat insulating material. SOLUTION: A vacuum heat insulating material 1 consists of a core material using powder with grain sizes showing volume frequency peaks at 100-400μm and at 1-50μm in a histogram representing a volume frequency to a grain size and a coating material covering the core material. Because these kinds of powder 4 is applied to the core material for the vacuum heat insulating material 1, a void in the powder is reduced and gas heat conductivity is reduced, while increase in conduction points between the powder is lowered and solid heat conductivity is not also increased, and consequently a heat insulating material with excellent heat insulating performance can be provided. As the grain sizes of the powder 4 are limited within a range of 100-400μm and within a range of 1-50μm, the vacuum heat insulating material 1 excellent in both of gas heat conductivity and solid heat conductivity can be provided.</p> |
