| 摘要 |
1346446 Silica MONSANTO CO 1 July 1971 [1 July 1970] 30800/71 Heading C1A [Also in Division C3] Anhydrous, synthetic, amorphous, pulverulent SiO 2 having (a) an average particle size of 0À5-4À0 Á, (b) a surface area of 40-600 m.<SP>2</SP>/g., (c) a bulk density of 1-30 lbs/cu. ft. and (d) a linseed oil absorption of from 1-4 lbs per lb. of SiO 2 , is calcined in air at 300-750‹ C. for at least 10 sees. to improve the flatting ability in coating compositions. The material treated may be an aerogel, xerogel, precipitated arc or pyrogenic SiO 2 . The SiO 2 may be heated for up to 6 hrs. at a pressure of 0À5-10 atm. in an oven, kiln or fluidized bed. |
