To provide a vacuum thermal insulation material capable of improving productivity and deterioration with age of thermal insulation performance.
This glass wool board which becomes a core material of the vacuum thermal insulation material holds its shape by pressurizing a glass fiber collection body 4 in a heated condition. By heating it at temperature of 480°C or more, viscosity of glass becomes 1018P or less to hold the shape by fusing a part of a glass constituent material at a contact point between glass fibers 2. A connection part 3 made of a glass fiber 2 constituent material is provided at the contact point between mutually connected glass fibers 2, and composition ratio of the connection part 3 is substantially the same as composition ratio of the glass fiber 2. This connection part 3 occurs at the contact point when pressurizing the glass fibers 2 whose viscosity is reduced by heating. It is possible to hold the shape when pressurizing even after releasing press and hold the glass wool board in the predetermined shape even if there is no connection material in fibers mutually by connection of the connection part 3 caused in a contact point part.
Tomoyasu Sakaguchi
Hiroki Naito
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