Amorphous silica

Details Amorphous silica Amorphous silica

2002-11-29

2010-02-16

Krass, Frederick (Department: 1612)

Drug, bio-affecting and body treating compositions

Dentifrices

C423S335000

Reexamination Certificate

active

07662363

ABSTRACT:
An amorphous silica suitable for use in a dental composition has a weight mean particle size in the range 3 to 15 μm with at least 90 per cent by weight of particles having a size below 20 μm, a Radioactive Dentine Abrasion (RDA) determined on an aqueous slurry of the silica powder of 100 to 220, a Pellicle Cleaning Ratio (PCR), when incorporated in a dental composition at 10 per cent by weight, greater than 85, the ratio of PCR to RDA being in the range 0.4:1 to less than 1:1 and having a Plastics Abrasion Value (PAV) in the range 11 to 19. A silica having the above properties is prepared by a precipitation route. The silica made available by the invention is also useful as an anti-blocking agent in plastics.

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Wulknitz, P. “Cleaning Power and Abrasivity of European Toothpastes”, Adv. Dent. Res. 11(4):576-579, Nov. 1997.

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