| 摘要 |
<p>Glass microbubbles having, on a weight basis, a composition consisting essentially of 70-80% SiO2, 8-15% CaO, 3-8% Na2O, and 2-6% B2O3, and about 0.2-1.5% SO3 and having a CaO:Na2O ratio of 1-3.5. These microbubbles, which are made of significantly less expensive raw materials than conventional products, can also be made with a higher percent "floaters" and a lower average density. Certain substitutions can be made for at least a portion of each of the first three oxides.</p> |
