High temperature-heat insulator and method for manufacturing three-dimensionally shaped insulator thereof
Disclosed is a heat insulator comprising a substrate comprising of a bulk of silica-based inorganic fiber containing a hydroxyl group; a metallic or ceramic infrared mediator held on at least a part of one surface of the substrate; and a silica cured product holding the infrared mediator on/in the substrate. As the infrared mediator, a metal foil or a ceramic particle may be used. This heat insulator exhibits excellent heat insulating performance in a high temperature range of 600° C. or more, and can be molded into a three-dimensional shape which can be directly mounted to a structure.
1. A high temperature-heat insulator comprising
a substrate comprising of a bulk of silica-based inorganic fiber containing a hydroxyl group;
a metallic infrared mediator which is a metal foil having a thermal emissivity of 0.3 or less held on at least a part of one surface of the substrate; and
a first silica cured product holding the infrared mediator on the substrate wherein the first silica cured product is a solidified material containing a layered silicate and crystalline silica powder,
wherein the metal foil is held on one surface of the substrate, and the other surface of the substrate faces a thermal source to be insulated; and
wherein the other surface comprises a second silica cured product holding a ceramic particle as a ceramic infrared mediator, wherein the second silica cured product is an inorganic polymer containing siloxane bond.
2. The high temperature-heat insulator according to claim 1 ,
wherein the second silica cured product is a dried or solidified material of a colloidal solution in which particles of anhydrous silicic acid and the ceramic particle are dispersed in aqueous medium.
3. The high temperature-heat insulator according to claim 1 , wherein the ceramic particle has a thermal emissivity of 0.6 to 0.9.
4. The high temperature-heat insulator according to claim 3 , wherein the ceramic particle has an average particle diameter of 0.5 to 4 μm.
5. The high temperature-heat insulator according to claim 1 , wherein the layered silicate is smectite.
6. The high temperature-heat insulator according to claim 1 , wherein the substrate is a nonwoven fabric or mat, both in which the silica-based inorganic fibers are entangled, or a three-dimensionally shaped molded article of the nonwoven fabric or mat.
7. The high temperature-heat insulator according to claim 1 , wherein the first silica cured product further comprises a dried sodium silicate.
8. The high temperature-heat insulator according to claim 1 , wherein the first silica cured product is a dry solidified product of suspension or paste containing crystalline silica powder, layered silicate, water, and water glass.