Granules based on pyrogenically produced aluminium oxide,...

Details Granules based on pyrogenically produced aluminium oxide,... Granules based on pyrogenically produced aluminium oxide,...

2002-08-06

2004-06-01

Marcheschi, Michael (Department: 1755)

Abrasive tool making process, material, or composition

With inorganic material

Metal or metal oxide

C501S127000, C502S355000, C502S414000, C424S691000, C106S003000, C106S401000, C423S625000

Reexamination Certificate

active

06743269

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to granules based on pyrogenically produced aluminium oxide, to the process for the production thereof, and to the use thereof.
2. Description of the Background
It is known to produce pyrogenic aluminium oxide by means of elevated temperature or flame hydrolysis from AlCl
3
(Ullmanns Enzyklopädie der technischen Chemie, 4th edition, volume 21, page 464 (1982)).
Pyrogenic aluminium oxides are distinguished by extreme fineness, correspondingly elevated specific surface area (BET), very high purity, spherical particle shape and the absence of pores. Due to these properties, there is increasing interest in pyrogenically produced aluminium oxides as supports for catalysts (D. Koth et al, Chem. Ing. Techn. 52, 628 (1980)). For this application, the pyrogenically produced aluminium oxide is mechanically formed, for example by means of tabletting machines.
SUMMARY OF THE INVENTION
The object accordingly arose of providing sprayed granules of pyrogenically produced aluminium oxide which may be used for a variety of purposes, such as, for example, catalyst supports.
It is another object of the invention to provide methods of making and using such granules, as well as to provide compositions containing the same.
The objects of the present invention, and others, may be accomplished with granules comprising, i.e., based on, pyrogenically produced aluminium oxide having the following physicochemical characteristics:
Average grain diameter:
5.0 to 150 &mgr;m
Tamped density:
300 to 1200 g/l.
The objects of the invention may also be accomplished with granules comprising pyrogenicaly produced aluminium oxide having the following physicochemical characteristics:
Average grain diameter:
5 to 160 &mgr;m
Tamped density:
300 to 1200 g/l
Carbon content:
0.3 to 12.0 wt. %.
The objects of the invention may also be accomplished with a process for the production of the granules described above, comprising dispersing pyrogenically produced aluminium oxide is dispersed in water and then spray drying.
The objects of the invention may also be accomplished with a composition selected from the group consisting of a catalyst support, glass, ceramic, abrasive agent, polishing agent, cosmetic, toner powder, paint and lacquer, which comprises the granules described above, and with methods of making the composition.
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the detailed description below.
DETAILED DESCRIPTION OF THE INVENTION
As described above, the average grain diameter of the inventive granules may be 5.0 to 150 &mgr;m and the tamped density may be 300 to 1200 g/l. In a preferred embodiment of the invention, the granules may exhibit an average grain diameter of 5.0 to 45 &mgr;m and a tamped density of 300 to 550 g/l. These ranges for the average grain diameter include all specific values and subranges therebetween, such as 10, 15, 20, 25, 50, 75, 100 and 125 &mgr;m. These ranges for the tamped density include all specific values and subranges therebetween, such as 350, 400, 500, 600, 700, 800, 900, 1000 and 1100 g/l.
The granules according to the invention may be produced by dispersing pyrogenically produced aluminium oxide in water, spray drying it and optionally heat treating the granules obtained at a temperature of 150 to 1100° C. for a period of 1 to 8 hours. This temperature range includes all specific values and subranges therebetween, such as 200, 250, 300, 400, 500, 600, 700, 800, 900, and 1000° C. This range for the time period includes all specific values and subranges therebetween, such as 2, 3, 4, 5, 6, and 7 hours.
The educt used may comprise an aluminium oxide as described in Ullmanns Enzyklopädie der technischen Chemie, 4th edition, volume 21, page 464(1982), incorporated herein by reference. Another educt which may be used is a pyrogenically produced aluminium oxide with an elevated surface area, which exhibits a BET specific surface area of greater than 115 m
2
/g, and the Sears value is greater than 8 ml/2 g.
Measured on a sample weight of 16 g, the dibutyl phthalate absorption of this aluminium oxide powder is not measurable (no detectable end point).
This pyrogenically produced aluminium oxide may be produced using the flame oxidation or preferably the flame hydrolysis method, wherein the starting material used is a vaporisable aluminium compound, preferably the chloride. This aluminium oxide is described in DE 199 42 291.0-41, incorporated herein by reference.
The present invention also provides granules based on pyrogenically produced aluminium oxide having the following physicochemical characteristics:
Average grain diameter:
5 to 160 &mgr;m
Tamped density:
300 to 1200 g/l, preferably 300-600 g/l
Carbon content:
0.3 to 12.0 wt. %, preferably 1.0 to 6.0 wt. %
The granules according to the invention may be produced by dispersing pyrogenically produced aluminium oxide in water, spray drying it, optionally heat treating the granules obtained at a temperature of 150 to 1000° C. for a period of 1 to 8 hours and then silanizing them.
Silanization may be performed using halosilanes, alkoxysilanes, silazanes and/or siloxanes.
The following substances may in particular be used as organosilanes:
(a)
Organosilanes of the type (RO)
3
Si(C
n
H
2n+1
) and (RO)
3
Si(C
n
H
2n−1
)
R =
alkyl, such as for example methyl, ethyl, n-propyl, i-propyl, butyl
n =
1-20
(b)
Organosilanes of the type R′
x
(RO)
y
Si(C
n
H
2n+1
) and R′
x
(RO)
y
Si(C
n
H
2n−1
)
R =
alkyl, such as for example methyl, ethyl, n-propyl, i-propyl, butyl
R′ =
alkyl, such as for example methyl, ethyl, n-propyl, i-propyl, butyl
R′ =
cycloalkyl
n =
1-20
x+y=
3
x =
1.2
y =
1.2
(c)
Haloorganosilanes of the type X
3
Si(C
n
H
2n+1
) and X
3
Si(C
n
H
2n−1
)
X =
Cl, Br
n =
1-20
(d)
Haloorganosilanes of the type X
2
(R′)Si(C
n
H
2n+1
) and X
2
(R′)Si(C
n
H
2n−1
)
X =
Cl, Br
R′ =
alkyl, such as for example methyl, ethyl, n-propyl, i-propyl, butyl
R′ =
cycloalkyl
n =
1-20
(e)
Haloorganosilanes of the type X(R′)
2
Si(C
n
H
2n+1
) and X(R′)
2
Si(C
n
H
2n−1
)
X =
Cl, Br
R′ =
alkyl, such as for example methyl, ethyl,
R′ =
cycloalkyl, n-propyl, i-propyl, butyl
n =
1-20
(f)
Organosilanes of the type (RO)
3
Si(CH
2
)
m
-R′
R =
alkyl, such as methyl, ethyl, propyl
m =
0.1-20
R′ =
methyl, aryl (for example C
6
H
5
, substituted phenyl residues)
—C
4
F
9
, OCF
2
—CHF—CF
3
, —C
6
F
13
, —O—CF
2
—CHF
2
—NH
2
, —N
3
, —SCN, —CH═CH
2
, —NH—CH
2
—CH
2
—NH
2
,
—N—(CH
2
—CH
2
—NH
2
)
2
—OOC(CH
3
)C═CH
2
—OCH
2
—CH(O)CH
2
—NH—CO—N—CO—(CH
2
)
5
—NH—COO—CH
3
, —NH—COO—CH
2
—CH
3
, —NH—(CH
2
)
3
Si(OR)
3
—S
x
—(CH
2
)
3
Si(OR)
3
—SH
- NR′R″R′″ (R′ = alkyl, aryl; R″ = H, alkyl, aryl; R′″ = H, alkyl, aryl, benzyl,
C
2
H
4
NR″″ R′″″ where R″″ = H, alkyl and R′″″ = H, alkyl)
(g)
Organosilanes of the type (R″)
x
(RO)
y
Si(CH
2
)
m
-R′
R″
=
alkyl
x+y = 2
=
cycloalkyl
x = 1.2
y = 1.2
m = 0.1 to 20
R′ =
methyl, aryl (for example C
6
H
5
, substituted phenyl residues)
—C
4
F
9
, OCF
2
—CHF—CF
3
, —C
6
F
13
, —O—CF
2
—CHF
2
—NH
2
, —N
3
, —SCN, —CH═CH
2
, —NH—CH
2
—CH
2
—NH
2
,
—N—(CH
2
—CH
2
—NH
2
)
2
—OOC(CH
3
)C═CH
2
—OCH
2
—CH(O)CH
2
—NH—CO—N—CO—(CH
2
)
5
—NH—COO—CH
3
, —NH—COO—CH
2
—CH
3
, —NH—(CH
2
)
3
Si(OR)
3
—S
x
—(CH
2
)
3
Si(OR)
3
—SH - NR′R″R′″ (R′ = alkyl, aryl; R″ = H, alkyl, aryl; R′″ = H, alkyl, aryl,
benzyl, C
2
H
4
NR″″ R′″″ where

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