Glass bubbles of increased collapse strength
AssigneeMinnesota Mining and Manufacturing Company
InventorPeter A. Howell
Life of this patent
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Abstract
Glass bubbles of increased collapse strength are prepared. The bubbles have an average particle density of 0.4 or more and are made of glass that consists essentially of SiO.sub.2 (60-90 weight-percent), alkali metal oxide (2-20 weight-percent), B.sub.2 O.sub.3 (1-30 weight-percent), sulfur (0.005 to 0.5 weight-percent), and other conventional glass-forming ingredients.
Claims34
Glass bubbles of average diameter between about 5 and 200 micrometers and average particle density of at least 0.4 gram/cubic centimeter consisting essentially of the following ingredients in the stated weight-percents:
- ______________________________________ SiO.sub.2 60-90 Alkali metal oxide 2-20 B.sub.2 O.sub.3 1-30 S 0.005-0.5 RO 0-25 RO.sub.2 (other than SiO.sub.2) 0-10 R.sub.2 O.sub.3 (other than B.sub.2 O.sub.3) 0-20 R.sub.2 O.sub.5 0-10 F 0-5 Other ingredients 0-2 ______________________________________
Free-flowing mass of glass particles, at least 85 volume-percent of which are glass bubbles that float on water, said glass bubbles having an average diameter between about 5 to 200 micrometers and an average particle density of at least 0.4 gram/cubic centimeter, and consisting essentially of the following ingredients in the stated weight-percents:
- ______________________________________ SiO.sub.2 60-90 Na.sub.2 O + K.sub.2 O + Li.sub.2 O 2-20 B.sub.2 O.sub.3 1-30 S 0.005-0.5 RO 0-25 RO.sub.2 (other than SiO.sub.2) 0-10 R.sub.2 O.sub.3 (other than B.sub.2 O.sub.3) 0-20 R.sub.2 O.sub.5 0-10 F 0-5 Other ingredients 0-2 ______________________________________
Free-flowing mass of glass particles, at least 85 volume-percent of which are glass bubbles that float on water, said glass bubbles having an average diameter between about 5 and 200 micrometers and an average particle density of at least 0.4 gram/cubic centimeter, and consisting essentially of the following ingredients in the stated weight-percent ranges:
- ______________________________________ SiO.sub.2 60-90 Na.sub.2 O + K.sub.2 O + Li.sub.2 O 2-20 B.sub.2 O.sub.3 2-10 S 0.005-0.2 RO 0-25 RO.sub.2 (other than SiO.sub.2) 0-10 R.sub.2 O.sub.3 (other than B.sub.2 O.sub.3) 0-20 R.sub.2 O.sub.5 0-10 F 0-5 Other ingredients 0-2 ______________________________________
Dependencies are inferred from the claim text.