1. Field of the Invention
This invention relates to a heat insulator and a structure using the heat insulator.
2. Prior Art
A heat insulator for buildings which heretofore has been known includes a heat insulator molded board such as Styrofoam (a registered trademark) to be integrally applied by being driven in the form to serve for a fill-up concrete block, too and an expanded urethane to be applied by being sprayed onto a concrete surface on a job site.
An organic heat insulator such as the above expanded urethane and Styrofoam to be applied on a job site has a very low thermal conductivity of 0.02 to 0.03 (kcal/mhr.degree.C.), exhibiting a remarkable heat-insulating property. But it has a disadvantage that it is easily flammable because it is organic.
In view of legal fire preventing regulations and to provide strength, a flame retardant material such as a plaster board is put on the organic heat insulator to form a base on which facing is required to be applied. This requires many construction steps to make a building fireproofed, resulting in a disadvantage requiring much labor.
As a heat insulator free from the above disadvantage, an expanded mortar, pearlite mortar and other lightweight mortar are used as an inorganic heat insulator.
Such an inorganic heat insulator is hard to burn. But it has a thermal conductivity of 0.2 to 0.3 (kcal/mhr.degree.C.) which is very large as compared with that (0.02 to 0.03 kcal/mhr.degree.C.) of an organic heat insulator. Therefore, it has a disadvantage that its heat-insulating performance is inferior to that of the organic heat insulator.
Thus, it is difficult to obtain a desired heat-insulating performance. And to obtain the desired performance, a very thick insulator is required
Heretofore, as the inorganic heat insulator for a building, there has been used a heat-insulating material such as an expanded mortar and pearlite mortar in which cement is mainly used in the form of matrix.
Such an expanded mortar and pearlite mortar are applied by a wet process such as spraying and troweling or a dry process in the form of a heat insulator molded board.
The above expanded mortar, pearlite mortar and other heat insulators are inorganic and are hard to burn because they use cement in the form of matrix. And they have properties which are expected to provide strength to some extent. But their thermal conductivity is 0.2 to 0.3 (kcal/mhr.degree.C.) which are very large as compared with 0.02 to 0.03 (kcal/mhr.degree.C.) of Styrofoam, expanded urethane and other organic heat insulators, being inferior in a heat-insulating performance.
Therefore, it is difficult to obtain a desired heat-insulating performance. To obtain the desired performance, it is required to use a very thick insulator.
On the other hand, the organic heat insulators such as an expanded urethane and Styrofoam which are applied on a job site have a thermal conductivity of 0.02 to 0.03 (kcal/mhr.degree.C.) which is very small, exhibiting a remarkable heat-insulating performance. But they have a disadvantage that they are easily flammable because they are organic.
In view of legal fire preventing regulations and strength, a flame retardant material such as a plaster board is put on the organic heat insulator to form a base on which facing is required to be applied. This requires many construction steps to make a building fireproofed, resulting in a disadvantage requiring much labor.