主权项 |
1. Glass particles comprising glass microbubbles, wherein the glass particles have a size distribution with a d50 in the range of from 15 to 100 microns, wherein the glass particles have a true density of less than 0.7 g/cm3, and wherein the glass particles comprise, on an equivalent weight basis: from 50 to 70 percent of silica, from 4 to 5 percent of boria, from 0.5 to 4 percent of zinc oxide, from 8 to 17 percent of calcia, from 0.8 to 7 percent of phosphorus pentoxide, greater than zero and less than 5 percent of alumina, and from 2 to 9 percent of sodium oxide. |