Carbon black granules
The invention concerns carbon black granules, a process for
their production and their use.
Carbon blacks are preferably processed as granulated
products, which are often referred to as carbon black
granules, beaded carbon black or pelletised carbon black.
The way in which the granulation is handled differs
according to the structure and surface area of the carbon
blacks. Thus, carbon blacks with a low structure
agglomerate more easily than carbon blacks with a high
structure.
Inks containing a dye having a particle size of 0.01 pm to
25 µm, a hydrocarbon resin, an oxidised polyethylene and a
resin as binder are known from US 5,981,625.
In addition, a process is known from US 4,397,652 for the
production of inks containing an adhesive, selected from
the group consisting of sorbitol, hydrogenated dextrose,
glucose, lactose, neopentyl glycol, mannitol, mannose and
polyethylene glycol, and a dust binder.
A carbon black composition containing carbon black and a
binder selected from the group comprising ethoxylated
esters and polyethers is known from. WO 96/21698.
The known carbon black beads have the disadvantages that
the carbon black beads are difficult to disperse and have a
low gloss when incorporated into printing inks. In
addition, such printing inks have poor flow properties,
high water absorption and poor free running behaviour on
the printing plate.

The object of the present invention is to provide carbon
black granules which when incorporated into printing inks
display a good dispersion state, high gloss, good flow
properties, low water absorption and good free running
behaviour on the printing plate.
The invention provides carbon black granules which are
characterised in that they contain a triester of sorbitan.
The carbon black granules can be in bead form.
All triesters of saturated, unsaturated or polyunsaturated
carboxylic acids can be used as sorbitan triester. The
carboxylic acids can be branched or unbranched. Sorbitan
trioleate, sorbitan trilaureate, sorbitan tristearate,
sorbitan tripalmeate or sorbitan triricinoleate can
preferably be used.
The carbon black granules can contain 1 to 15 wt.%,
preferably 3 to 7 wt.%, of the sorbitan triester, relative
to the carbon black granules.
The carbon black granules can have a BET surface area of 10
to 300 m2/g, preferably 45 to 110 m2/g.
The invention also provides a process for the production of
carbon black granules which is characterised in that a
powdered carbon black or beaded carbon black is granulated
with a sorbitan triester.
Granulation can be performed in a ring-layer mix-
pelletizer, a bead machine or a bead drum.
Wet- or dry-beaded carbon black can be used as beaded
carbon black.

The carbon black granules can be dried after granulation.
The dryer temperature can be between 100° and 250°C,
preferably between 150° and 200°C. The temperature of the
carbon black granules on leaving the dryer can be between
30° and 100°C, preferably between 40° and 70°C.
The carbon black granules according to the invention can be
post-beaded.
All types of carbon black can in principle be granulated
with the process according to the invention. Furnace
blacks, lamp blacks, gas blacks, channel black, thermal
black, acetylene black, plasma black, inversion black,
known from DE 195 21 565, Si-containing carbon blacks,
known from WO 98/45361 or DE 19613796, or metal-containing
carbon blacks, known from WO 98/42778, arc blacks and
carbon-containing materials that are secondary products of
chemical production processes can be used. Carbon blacks
having BET surface areas of between 10 and 300 m2/g can
preferably be used.
Printex 25, Printex 275, Printex 30, Printex 300, Printex
35 and Printex 45 from Degussa AG, for example, can be used
as starting carbon black.
The sorbitan triester can be dissolved, for example in
mineral oils or vegetable oils, preferably in oils that can
be used in printing inks.
The sorbitan triester can. be used as a 10 and 90 wt. %
solution.
An additional binder can be added to the sorbitan triester.
For example, resins or waxes, as well as numerous other
substances, either alone or in combination with one
another, can be added as additional binder.

In a preferred embodiment, no additional binder can be
added to the sorbitan triester.
The carbon black granules according to the invention can be
used in polymer blends, such as rubber and plastics for
example, lacquers, inks, in particular printing inks,
pigments and the many other application forms of carbon
black. In a preferred application form the carbon black
granules according to the invention can be used in oil-
based offset printing inks.
The invention also provides printing inks which are
characterised in that they contain the carbon black
granules according to the invention.
The printing inks can contain conventional components, such
as e.g. binders, solvents and diluents, as well as other
auxiliary substances.
The printing inks can contain 5 to 45 wt.%, preferably 10
to 25 wt.%, of carbon black granules according to the
invention.
The printing inks can be produced by premixing the carbon
black granules according to the invention with printing ink
binders and then dispersing and grinding them.
The printing inks according to the invention can be used in
offset printing.
The carbon black granules according to the invention have
the advantage that, when incorporated into printing inks,
they display a good dispersion state, high gloss, good flow
properties, low water absorption and good free running
behaviour on the printing plate.

Example 1-3 :
Production of carbon black granules
The carbon black granules according to the invention are
produced by continuously feeding the starting carbon black
to the heated ring-layer mix-pelletizer (RMG) by means of a
gravimetric powder metering unit. The sorbitan trioleate is
optionally heated to allow it to be pumped more readily and
also to achieve better atomisation. The sorbitan trioleate
is sprayed in with air by means of two-fluid atomisation
using a feed nozzle which is 12.5 cm away from the centre
of the carbon black filling nozzle. The partially
granulated product discharged from the ring-layer mix-
pelletizer is post-beaded in a granulating drum to round
off the granules and to further reduce the fines. Printex
25 (Px25) is used as starting carbon black in Example 1,
Printex 35 (Px35) in Example 2 and Printex 45 (Px45) in
Example 3. In all three examples sorbitan trioleate (STO)
is used as the sorbitan triester. The experimental
conditions are described in Table 1.


The analytical data for the carbon black beads is
determined in accordance with the following standards:
BET surface area ASTM 6556-0la,
Fines: ASTM D-1508-01
Volatile matter 950 °C DIN 53552
Bead abrasion DIN 53583
Bulk density DIN 53600
The analytical data for examples 1 to 3 is set out in
Table 2.


Comparative example 4-6
The same starting carbon blacks as used in example 1-3, but
without the addition of additive, are granulated as
comparative examples.
The experimental conditions are described in Table 3.

The carbon black granules according to the invention
(example 1-3) display a higher bulk density in comparison
to the comparative examples 4-6.
Example 7-9
For examples 7 to 9 the additive is applied to dry-beaded
carbon black. To this end, dry-beaded carbon black from
examples 4 to 6 is placed in the granulating drum. The
sorbitan trioleate is heated to 80°C to allow it to be
pumped more readily and also to achieve better atomisation.
With the drum rotating, the sorbitan trioleate is sprayed
with air onto the carbon black bed by means of two-fluid
atomisation. When the addition is completed, the drum is
allowed to run for a further 10 minutes.
The experimental conditions are described in Table 5.


The analytical data for comparative examples 7 to 9 is set
out in Table 6.

Example 10-12
Offset printing ink:
The following components are mixed in a high-speed mixer:
12.8 % ER resin 125
12.0 % Necires LF 220/130
10.4 % Albertol KP 172
10.4 % Setalin V402
0.4 % Cycloxim FF
26.0 % Automotive oil F 4/7
8.0 % Automotive oil F 6/9
ER resin 125 is a hydrocarbon compound from American
Gilsonite Company USA (supplied by Worlee Chemie GmbH
Hamburg). Necires LF 220/130 is a hydrocarbon resin from

Nevcin Polymers B.V. Holland. Albertol KP 172 is a phenolic
resin-modified colophony resin from Solutia Germany GmbH &
Co. KG Germany. Setalin V402 is an alkyd resin from Akzo
Nobel Resins Holland. Cycloxim FF is a cyclohexanone oxime
from Acima AG Switzerland. Automotive oil F 4/7 is an acid-
treated petroleum distillate from Haltermann Products
Hamburg. Automotive oil F 6/9 is an acid-treated petroleum
distillate from Haltermann Products Hamburg.
After the components have been intimately mixed, a further
20.0 % carbon black is added. After being predispersed for
15 minutes in the high-speed mixer (Getzmann), the mixture
is then ground in a mill (Netzsch Attritor) with 3 mm steel
balls until the grindometer fineness is below 5 µm. The
carbon blacks used in the printing inks are listed in Table
7.

The viscosity, yield point and flow behaviour of the
printing ink is determined (Table 8).



After de-aeration,using a triple roller mill, the printing ink is applied to paper in a
test model printing device. The ink
is applied in a 1.5 g/m2 layer onto APCO paper. After 24 h
the optical density, gloss and yellow value b* in
accordance with CieLab are determined on the dried print
(Table 12) .

The printing inks (example 10-12) with the carbon black
granules according to the invention display an improved,
lower viscosity, better flow and higher gloss than the
printing inks (example 13-15) with the comparative
examples.

After de-aeration, using a triple roller mill, the printing ink is applied to paper in a
test model printing device. The ink
is applied in a 1.5 g/m2 layer onto APCO paper. After 24 h
the optical density, gloss and yellow value b* in
accordance with CieLab are determined on the dried print
(Table 9).

Comparative example 13-15
For the sake of comparison, the carbon black granules
according to example 4 to 6 are likewise used in printing
inks in an analogous way to example 10 to 12, and the inks
are analysed (Table 10).

The viscosity, yield point and flow behaviour of the
printing ink is determined (Table 11).

Example 16
In an analogous way to examples 7 to 9, Printex 275 (Px275,
furnace black with a BET surface area of 53.3 m2/g) is used
as the starting carbon black and a granulated carbon black
is produced with sorbitan trioleate (Table 13).


Example 17-18
As in examples 10-12, the Printex 275 granulated with
sorbitan trioleate from Example 16 and conventionally dry-
beaded starting carbon black Printex 275 are incorporated
into printing inks (Table 15).

The behaviour with regard to water is analysed using a
Tack-O-Scope (Table 16).

The printing ink (Example 17) with the carbon black
granules according to the invention displays a higher tack
after contact with water than the printing ink (Example 18)
with the comparative carbon black.

Example 19-20
Two printing inks are produced with commercial Printex 35
as described in example 10-12. 5% sorbitan trioleate
(Example 19) and 5% sorbitan monooleate (Example 20),
relative to carbon black, are used in the production. The
behaviour of both inks with regard to water is analysed
using a Tack-O-Scope (Table 17).

The printing ink (Example 19) with the carbon black
granules according to the invention displays a higher tack,
which is also higher even after contact with water, as well
as lower water absorption and better free running
behaviour.

WE CLAIM:
1. Carbon black granules, characterized in that they contain a sorbitan
triester.
2. Carbon black granules as claimed in claim 1, wherein the sorbitan
triester is a triester of saturated, unsaturated or polyunsaturated carboxylic
acids.
3. Carbon black granules as claimed in claim 1, wherein the sorbitan
triester is sorbitan trioleate, sorbitan, trilaureate, sorbitan tristearate, sorbitan
tripalmeate or sorbitan triricinoleate,
4. Process for the production of carbon black granules as claimed in claim
1, wherein a powdered carbon black or beaded carbon black is granulated
with a sorbitan triester.
5. Process for the production of carbon black granules as claimed in claim
4, wherein carbon black with BET surface areas of between 10 and 300 m2/g
is used.
6. Process for the production of carbon black granules as claimed in claim
4, whererin sorbitan trioleate, sorbitan trilaureate, sorbitan tristearate,
sorbitan tripalmeate or sorbitan triricinoleate is used as the sorbitan triester.

7. Process for the production of carbon black granules as claimed in claim
4, wherein the granulation is performed in a bead machine, ring-layer mix-
pelletizer or bead drum.

Carbon black granules, characterised in that they contain a sorbitan
triester.