Indian Patents. 250520:A PROCESS FOR THE PREPARATION OF GAS BLACK

Title of Invention	A PROCESS FOR THE PREPARATION OF GAS BLACK
Abstract	A process for the preparation of the carbon black according to the invention, wherein a salt solution is converted into an aerosol and this is then introduced into the carbon black formation zone, is furthermore described. The carbon black according to the invention can be used in inks, paints, lacquers, printing inks and ink-jet inks, and for colouring plastics.

Full Text	The invention relates to a carbon black, a process for its preparation and its use. DE 19650500 discloses doped, pyrogenically prepared oxides of metals and / or metal oxides which are doped with one or more doping components in an amount of 0.00001 to 20 wt.-%. The doped pyrogenically prepared oxides are prepared by adding an aerosol which comprises an aqueous solution of a metal and / or metal oxide to the gas mixture during flame hydrolysis of vaporizable compounds of metals and / or metal oxides. A gas black process (DRP 29261, DE-PS 2931907, DE-PS 671739, Carbon Black, Prof. Donnet, 1993 by MARCEL DECCER, INC, New York, page 57 et seq.) in which a hydrogen- containing carrier gas loaded with oil vapours is burned in excess air at numerous discharge openings is furthermore known. The flames impinge on water-cooled rollers, which interrupts the combustion reaction. Some of the carbon black formed inside the flames is precipitated on the rollers and is scraped off from these. The carbon black remaining in the stream of waste gas is separated off in filters. The channel black process (Carbon Black, Prof. Donnet, 1993 by MARCEL DECCER, INC, New York, page 57 et seq.) in which a large number of small flames fed by natural gas burn against water-cooled iron channels is furthermore known. The carbon black deposited on the iron channels is scraped off and collected in a funnel. The carbon blacks prepared by these processes have numerous oxygen-functional groups on the surface and, due to the process, are highly structured, that is to say the carbon blacks consist of extended and branched aggregates. A disadvantage of the known carbon blacks is that due to the process they have a very high structure and there is no possibility of reducing this directly during the preparation process. The object of the present invention is to provide a carbon black which has low structure, a lower viscosity and higher depth of colour in the lacquer and renders possible a higher carbon black concentration in binder systems, at a constant viscosity, compared with carbon blacks of which the structure has not been reduced. A further object of the present invention is to adjust the structure of the carbon black in a targeted manner in the carbon black preparation process. The invention provides a carbon black, wherein the OAN, measured on the beaded carbon black, is less than 120 ml/100 g, preferably less than 110 ml/100 g, particularly preferably less than 100 ml/100 g. The carbon black can have a COAN, measured on the beaded carbon black, of less than 90 ml/100 g, preferably less than 85 ml/100 g, particularly preferably less than 80 ml/100 g. The carbon black can have a difference, measured on the beaded carbon black, between the OAN and COAN of less than 30 ml/100 g, preferably less than 25 ml/100 g, particularly preferably less than 20 ml/100 g. The carbon black can be a flame black, gas black or channel black. The potassium content of the carbon black, measured on the carbon black powder, can be greater than 5 ug/g, preferably greater than 10 ug/g, particularly preferably greater than 50 ug/g. The potassium can be randomly distributed in the entire carbon black particle. The BET surface area of the carbon black can be 50 m2/g to 500 m2/g, preferably 100 m2/g to 400 m2/g. The carbon black according to the invention can be non- treated or after-treated, for example oxidized, functionalized or beaded. The invention also provides a process for the preparation of the carbon black according to the invention, which comprises converting a salt solution into an aerosol with a gas, preferably air, nitrogen, hydrogen and/or hydrocarbon, and then introducing this into the carbon black formation zone. The aerosol can be mixed into the carbon black raw material before the burner. In particular, in the gas black process the aerosol can be mixed into the carrier gas/oil vapour mixture before the burner. The salt solution can be a solution of salt in water, alcohol or oil. The salt solution can comprise any salt which dissolves in water, alcohol or oil and can be converted into an aerosol. This can be, for example, an alkali metal or alkaline earth metal salt solution, preferably potassium salt solution, particularly preferably a potassium carbonate solution. The aerosol can be prepared by a procedure in which a salt solution is atomized by atomizing air with an atomizing nozzle and the aerosol mist which forms is conveyed by air from the side out of the atomizing vessel into a heating zone. The atomizing nozzle can comprise two nozzles directed against each other, through which the liquid is fed together with the atomizing air. The salt solution in the atomizing vessel which has not been converted into the aerosol can pass downwards from the atomizing vessel into a reflux tank. In the heating zone, the aerosol mist can be heated up to the extent that the salt solution no longer condenses. The temperature of the heating zone can be 50°C to 400°C. The device for the preparation of the aerosol can be made of glass, ceramic or high-grade steel. The carbon blacks according to the invention can be used for the preparation of inks, paints, lacquers, printing inks and ink-jet inks, and for colouring plastics. The carbon blacks according to the invention have the advantages that the structure is reduced and they have a low viscosity and relatively high depth of colour in lacquer. They also render possible higher carbon black concentrations in binder systems, at the same viscosity, compared with carbon blacks of which the structure has no- been reduced. Example: Figure 1 shows a diagram of the construction of the pilot plant. Carbon black raw material I GN from Rutgers Chemicals AG is vaporized at the temperatures stated in table 1 in a commercially available thin film evaporator. The oil vapour is fed by the hydrogen gas stream stated in table 1 to a gas black apparatus. Directly before the burner (DE-PS 671739) the amounts of air and aerosol stated in the table are admixed to the gas and the mixture is fed to the flames. The aerosol is produced in an apparatus (DE 19650500) which comprises an atomizing region and a heating zone. In the atomizing region potassium carbonate solution with the concentrations stated in the table is fed to two nozzles which are directed against each other and produce a fine mist with the aid of the atomizing air. Condensed solution flows out of the apparatus. The mist is fed with the conveying air into the heating zone and is stabilized there at 180°C. The carbon black produced is separated out in commercially available filter units. The beaded carbon black is prepared from the carbon black powder in commercially available beading units. The preparation conditions and results of examples 1-4 are shown in table 1. Test methods: Potassium content: Exactly 2 g of sample are weighed into a clean platinum crucible. The sample is ashed at 600oC in a muffle oven overnight. The residues are dissolved in 5 ml warm hydrochloric acid (3 0%, high purity) and the solution is topped up to 5 0 ml with highly pure water. The potassium content of the solution is determined by means of atomic absorption spectrometry (AAS). BET ASTM D 4820 STSA ASTM D 5816 Transmission ASTM D 1618 OAN ASTM D 2414, but with a weight of 15 g carbon black and paraffin oil COAN ASTM D 3 4 93, but with a weight of 15 g carbon black and paraffin oil Oil requirement: The carbon black sample is dried for 1 hour at 115°C. The sample is then cooled for approx. 30 minutes in a desiccator. In the case of beaded carbon black, the carbon black must be comminuted with a steel spatula before addition of the oil, so that a paste just as homogeneous as that for the pulverulent carbon blacks is obtained. The oil requirement is determined by dropwise addition of linseed oil varnish according to DIN 55 932 (Alberdingk, Krefeld) from a 2 ml burette to 0.5 g carbon black and grinding with an elastic steel spatula. The end point of the addition of oil is reached when a homogeneous standing paste has formed. A homogeneous standing paste exists when again ana appropriate brought to the set value with AMP. In accordance with DIN 54453 and DIN 53019, the viscosity is determined on the millbase at various shear gradients using a rotary viscometer (Visco-Tester 550, with PK 100 plate/cone 1°) from Haake. WE CLAIM : 1. A process for the preparation of gas black which comprises converting a salt solution into an aerosol with a gas and then introducing this into the gas black formation zone, wherein the said aerosol is mixed into carbon black raw material before the burner. 2. The process as claimed in claim 1, wherein preferably the aerosol is mixed into the carrier gas / oil vapour mixture before the burner. A process for the preparation of the carbon black according to the invention, wherein a salt solution is converted into an aerosol and this is then introduced into the carbon black formation zone, is furthermore described. The carbon black according to the invention can be used in inks, paints, lacquers, printing inks and ink-jet inks, and for colouring plastics.

Full Text

The invention relates to a carbon black, a process for its
preparation and its use.
DE 19650500 discloses doped, pyrogenically prepared oxides
of metals and / or metal oxides which are doped with one or
more doping components in an amount of 0.00001 to 20 wt.-%.
The doped pyrogenically prepared oxides are prepared by
adding an aerosol which comprises an aqueous solution of a
metal and / or metal oxide to the gas mixture during flame
hydrolysis of vaporizable compounds of metals and / or
metal oxides.
A gas black process (DRP 29261, DE-PS 2931907, DE-PS
671739, Carbon Black, Prof. Donnet, 1993 by MARCEL DECCER,
INC, New York, page 57 et seq.) in which a hydrogen-
containing carrier gas loaded with oil vapours is burned in
excess air at numerous discharge openings is furthermore
known. The flames impinge on water-cooled rollers, which
interrupts the combustion reaction. Some of the carbon
black formed inside the flames is precipitated on the
rollers and is scraped off from these. The carbon black
remaining in the stream of waste gas is separated off in
filters.
The channel black process (Carbon Black, Prof. Donnet, 1993
by MARCEL DECCER, INC, New York, page 57 et seq.) in which
a large number of small flames fed by natural gas burn
against water-cooled iron channels is furthermore known.
The carbon black deposited on the iron channels is scraped
off and collected in a funnel.

The carbon blacks prepared by these processes have numerous
oxygen-functional groups on the surface and, due to the
process, are highly structured, that is to say the carbon
blacks consist of extended and branched aggregates.
A disadvantage of the known carbon blacks is that due to
the process they have a very high structure and there is no
possibility of reducing this directly during the
preparation process.
The object of the present invention is to provide a carbon
black which has low structure, a lower viscosity and higher
depth of colour in the lacquer and renders possible a
higher carbon black concentration in binder systems, at a
constant viscosity, compared with carbon blacks of which
the structure has not been reduced. A further object of the
present invention is to adjust the structure of the carbon
black in a targeted manner in the carbon black preparation
process.
The invention provides a carbon black, wherein the OAN,
measured on the beaded carbon black, is less than
120 ml/100 g, preferably less than 110 ml/100 g,
particularly preferably less than 100 ml/100 g.
The carbon black can have a COAN, measured on the beaded
carbon black, of less than 90 ml/100 g, preferably less
than 85 ml/100 g, particularly preferably less than
80 ml/100 g.
The carbon black can have a difference, measured on the
beaded carbon black, between the OAN and COAN of less than
30 ml/100 g, preferably less than 25 ml/100 g, particularly
preferably less than 20 ml/100 g.

The carbon black can be a flame black, gas black or channel
black.
The potassium content of the carbon black, measured on the
carbon black powder, can be greater than 5 ug/g, preferably
greater than 10 ug/g, particularly preferably greater than
50 ug/g. The potassium can be randomly distributed in the
entire carbon black particle.
The BET surface area of the carbon black can be 50 m2/g to
500 m2/g, preferably 100 m2/g to 400 m2/g.
The carbon black according to the invention can be non-
treated or after-treated, for example oxidized,
functionalized or beaded.
The invention also provides a process for the preparation
of the carbon black according to the invention, which
comprises converting a salt solution into an aerosol with a
gas, preferably air, nitrogen, hydrogen and/or hydrocarbon,
and then introducing this into the carbon black formation
zone.
The aerosol can be mixed into the carbon black raw material
before the burner. In particular, in the gas black process
the aerosol can be mixed into the carrier gas/oil vapour
mixture before the burner.
The salt solution can be a solution of salt in water,
alcohol or oil.
The salt solution can comprise any salt which dissolves in
water, alcohol or oil and can be converted into an aerosol.

This can be, for example, an alkali metal or alkaline earth
metal salt solution, preferably potassium salt solution,
particularly preferably a potassium carbonate solution.
The aerosol can be prepared by a procedure in which a salt
solution is atomized by atomizing air with an atomizing
nozzle and the aerosol mist which forms is conveyed by air
from the side out of the atomizing vessel into a heating
zone.
The atomizing nozzle can comprise two nozzles directed
against each other, through which the liquid is fed
together with the atomizing air.
The salt solution in the atomizing vessel which has not
been converted into the aerosol can pass downwards from the
atomizing vessel into a reflux tank.
In the heating zone, the aerosol mist can be heated up to
the extent that the salt solution no longer condenses. The
temperature of the heating zone can be 50°C to 400°C.
The device for the preparation of the aerosol can be made
of glass, ceramic or high-grade steel.
The carbon blacks according to the invention can be used
for the preparation of inks, paints, lacquers, printing
inks and ink-jet inks, and for colouring plastics.
The carbon blacks according to the invention have the
advantages that the structure is reduced and they have a
low viscosity and relatively high depth of colour in
lacquer. They also render possible higher carbon black
concentrations in binder systems, at the same viscosity,

compared with carbon blacks of which the structure has no-
been reduced.

Example:
Figure 1 shows a diagram of the construction of the pilot
plant.
Carbon black raw material I GN from Rutgers Chemicals AG is
vaporized at the temperatures stated in table 1 in a
commercially available thin film evaporator. The oil vapour
is fed by the hydrogen gas stream stated in table 1 to a
gas black apparatus. Directly before the burner (DE-PS
671739) the amounts of air and aerosol stated in the table
are admixed to the gas and the mixture is fed to the
flames. The aerosol is produced in an apparatus (DE
19650500) which comprises an atomizing region and a heating
zone. In the atomizing region potassium carbonate solution
with the concentrations stated in the table is fed to two
nozzles which are directed against each other and produce a
fine mist with the aid of the atomizing air. Condensed
solution flows out of the apparatus. The mist is fed with
the conveying air into the heating zone and is stabilized
there at 180°C. The carbon black produced is separated out
in commercially available filter units. The beaded carbon
black is prepared from the carbon black powder in
commercially available beading units.
The preparation conditions and results of examples 1-4 are
shown in table 1.

Test methods:
Potassium content:
Exactly 2 g of sample are weighed into a clean platinum
crucible. The sample is ashed at 600oC in a muffle oven
overnight. The residues are dissolved in 5 ml warm
hydrochloric acid (3 0%, high purity) and the solution is
topped up to 5 0 ml with highly pure water. The potassium
content of the solution is determined by means of atomic
absorption spectrometry (AAS).
BET ASTM D 4820
STSA ASTM D 5816
Transmission ASTM D 1618
OAN ASTM D 2414,
but with a weight of 15 g carbon
black and paraffin oil
COAN ASTM D 3 4 93,
but with a weight of 15 g carbon
black and paraffin oil
Oil requirement:
The carbon black sample is dried for 1 hour at 115°C. The
sample is then cooled for approx. 30 minutes in a
desiccator. In the case of beaded carbon black, the carbon
black must be comminuted with a steel spatula before
addition of the oil, so that a paste just as homogeneous as
that for the pulverulent carbon blacks is obtained.
The oil requirement is determined by dropwise addition of
linseed oil varnish according to DIN 55 932 (Alberdingk,
Krefeld) from a 2 ml burette to 0.5 g carbon black and
grinding with an elastic steel spatula. The end point of
the addition of oil is reached when a homogeneous standing
paste has formed. A homogeneous standing paste exists when
again ana appropriate
brought to the set value with AMP.
In accordance with DIN 54453 and DIN 53019, the viscosity
is determined on the millbase at various shear gradients
using a rotary viscometer (Visco-Tester 550, with PK 100
plate/cone 1°) from Haake.

WE CLAIM :
1. A process for the preparation of gas black which comprises
converting a salt solution into an aerosol with a gas and then
introducing this into the gas black formation zone, wherein
the said aerosol is mixed into carbon black raw material
before the burner.
2. The process as claimed in claim 1, wherein preferably the
aerosol is mixed into the carrier gas / oil vapour mixture
before the burner.

A process for the preparation of the carbon black according to the invention,
wherein a salt solution is converted into an aerosol and this is then
introduced into the carbon black formation zone, is furthermore described.
The carbon black according to the invention can be used in inks, paints,
lacquers, printing inks and ink-jet inks, and for colouring plastics.

A PROCESS FOR THE PREPARATION OF GAS BLACK

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