| 摘要 |
<p>A fire retardant, intumescent composition is provided which comprises a mixture of alkali metal silicate, represented by the formula M20:xSiO2 in which M is the alkali metal; an oxy boron compound selected from boric acid or salts of Group I and II elements; and water; in which the weight ratio x ranges from about 1.5 to about 4, the molar ratio of boron to M is between about 0.2 and 0.9, and the water comprises about 5 to 15 weight percent of the total composition. These compositions are made by mixing an alkali metal silicate sol with a borate (e.g., boric acid) to form a gel which is dried in an oven. The resulting residue is crumbled to granules. A fire retardant which is relatively insoluble and has improved stability to long term exposure to water and humidity is formed. Various parameters (e.g., the weight ratio x, the amount of water present, and the ratio of boron to sodium) can be adjusted to control the amount of intumescence retained after exposure to water and also to control the temperature of intumescence. Granules made of these compositions have many applications, including incorporation into asphalt roofing materials.</p> |
