Gas-filled glass beads and method of making
AssigneeGlaverbel
InventorMarcel Delzant
Life of this patent
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Abstract
A method of producing gas filled hollow glass beads comprises the steps of: i. manufacturing hollow glass beads having an alkali content of at least 20% calculated as weight per cent of oxide in the bead, ii. exposing the beads to an acidic treatment medium, for example HCl, HNO.sub.3, H.sub.2 SO.sub.4, SO.sub.2, SO.sub.3, to reduce the alkali content of the beads to not more than 15%, and iii. causing gas to diffuse into the beads.
Claims15
A method of producing gas-filled hollow glass beads comprising the steps of manufacturing hollow glass beads having an alkali content of at least 20% calculated as weight % of oxide in the bead, contacting the beads with an acidic treatment medium to reduce the alkali content of the beads to not more than 15%, and causing nonhydrogen gas to diffuse into the beads after manufacture thereof by exposing said beads to said gas at a pressure greater than one atmosphere.
Dependencies are inferred from the claim text.