Appeal No. 1998-1353 Page 2
Application No. 08/488,288
BACKGROUND
Appellants’ invention relates to a composition in the form of a free-flowing powder of
agglomerates and a method of forming the agglomerates without flocculation. The agglomerates are
prepared from a mixture of a binder, solvent and oxide particles comprising SiO , TiO , ZrO , Al O or2 2 2 2 3
a mixture thereof obtained by hydrolytic polycondensation of alkoxides and having a surface modified
by covalently bonded organic groups. The oxide particles are monodisperse, i.e. the particles have a
narrow size distribution. According to the specification at page 3, “[t]he term monodisperse is to be
understood as meaning that the particles of a certain diameter have the lowest possible particle size
scatter lying within a very narrow range.” A standard deviation of particle diameter of less than 10%
and in particular less than 5% is preferred. The monodisperse oxide particles have a diameter between
10 nm and 10 µm. The binder, solvent and oxide particles are mixed together to form a suspension or
dispersion and then the solvent is removed by distillation. The resulting agglomerates contain between
70-95% by weight of oxide particles and 5-30% by weight binder. The agglomerates have a diameter
of 1-500 µm. Claims 1 and 6 are illustrative:
1. Preparations of monodisperse spherical oxide particles having a particle diameter between
10 nm and 10 µm and an essentially non-volatile binder in the form of a free-flowing powder of
agglomerates having a diameter of between 1 µm and 500 µm, in which the particles are bonded to one
another by the binder and in which 70 to 95% by weight of oxide particles and 30 to 5% by weight of
binder are present, obtainable by mixing the oxide particles homogeneously with the binder in a
corresponding ratio together with a solvent which is volatile being present in a weight ratio of 1:1 to
1:100, and then removing the solvent from the resulting suspension or dispersion by distillation, wherein
the monodisperse spherical oxide particles comprise SiO , TiO , ZrO , Al O or a mixture thereof, are2 2 2 2 3
Page: Previous 1 2 3 4 5 6 7 8 9 10 Next
Last modified: November 3, 2007