U.S. patent application number 09/828384 was filed with the patent office on 2001-08-23 for process for producing briquetted and pressed granular material and use thereof.
This patent application is currently assigned to Bayer Aktiengesellschaft, a corporation of Germany. Invention is credited to Eitel, Manfred, Linde, Gunter, Schmidt-Park, Olaf, Steiling, Lothar.
Application Number | 20010015388 09/828384 |
Document ID | / |
Family ID | 26024842 |
Filed Date | 2001-08-23 |
United States Patent
Application |
20010015388 |
Kind Code |
A1 |
Linde, Gunter ; et
al. |
August 23, 2001 |
Process for producing briquetted and pressed granular material and
use thereof
Abstract
The present invention relates to a process for producing
briquetted and pressed granular material and the use thereof for
coloring building materials, such as concrete and asphalt, and
organic media, such as paint systems, plastics and colored
pastes.
Inventors: |
Linde, Gunter; (Krefeld,
DE) ; Schmidt-Park, Olaf; (Krefeld, DE) ;
Eitel, Manfred; (Kempen, DE) ; Steiling, Lothar;
(Leverkusen, DE) |
Correspondence
Address: |
CONNOLLY BOVE LODGE & HUTZ LLP
1220 Market Street
P.O. Box 2207
Wilmington
DE
19899
US
|
Assignee: |
Bayer Aktiengesellschaft, a
corporation of Germany
|
Family ID: |
26024842 |
Appl. No.: |
09/828384 |
Filed: |
April 6, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09828384 |
Apr 6, 2001 |
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09505041 |
Feb 16, 2000 |
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6241167 |
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09505041 |
Feb 16, 2000 |
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08827660 |
Apr 10, 1997 |
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6079644 |
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Current U.S.
Class: |
241/3 |
Current CPC
Class: |
C08K 3/04 20130101; C01P
2006/60 20130101; C09C 1/24 20130101; C04B 18/028 20130101; C01P
2006/20 20130101; C01P 2004/50 20130101; C09D 7/68 20180101; C01P
2004/84 20130101; C08K 3/22 20130101; C09C 1/58 20130101; C09D
17/005 20130101; C01P 2006/11 20130101; C09D 7/61 20180101; C01P
2004/51 20130101; C01P 2006/82 20130101; C01P 2004/60 20130101;
C09C 1/3638 20130101; C04B 18/02 20130101; C01P 2006/10 20130101;
C08L 95/00 20130101; C09D 17/004 20130101; C09C 1/346 20130101;
C09C 1/60 20130101; C09C 1/34 20130101; C01P 2004/61 20130101; C09C
3/046 20130101; C04B 18/022 20130101; C08K 9/08 20130101; C04B
2103/54 20130101; C09C 3/045 20130101; C04B 18/02 20130101; C04B
14/022 20130101; C04B 18/02 20130101; C04B 20/0076 20130101; C04B
20/026 20130101; C04B 20/10 20130101; C04B 2103/54 20130101; C04B
18/02 20130101; C04B 20/0076 20130101; C04B 14/022 20130101; C04B
14/30 20130101; C04B 20/026 20130101; C04B 20/10 20130101; C04B
18/028 20130101; C04B 14/022 20130101; C04B 18/028 20130101; C04B
2103/54 20130101; C04B 18/028 20130101; C04B 14/30 20130101; C04B
20/008 20130101; C04B 18/028 20130101; C04B 20/008 20130101; C04B
2103/54 20130101; C08L 95/00 20130101; C08L 2666/72 20130101 |
Class at
Publication: |
241/3 |
International
Class: |
B02C 019/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 18, 1996 |
DE |
19615261.5 |
Sep 18, 1996 |
DE |
19638042.1 |
Claims
1. A process for producing briquetted and pressed granular material
from inorganic pigments and auxiliary substances, comprising the
steps of a) mixing one or more inorganic pigments with one or more
auxiliary substances promoting processability, b) subjecting this
mixture to a pressing or briquetting step to produce a pressed or
briquetted product, c) comminuting the pressed or briquetted
product to produce a comminuted product, d) dividing the comminuted
product into two or more fractions, e) removing a first fraction of
particles having at least 85% of the particles at least 80 .mu.m as
product and transferring the other fraction or fractions out of the
process.
2. The process according to claim 1, wherein prior to step c) the
pressed or briquetted product from b) is divided into two fractions
including a coarse fraction having at least 85% of particles larger
than 500 .mu.m and a fine fraction, passing the coarse fraction to
step c) and passing the fine fraction to step d) for division in
step d), separate from or together with the comminuted product from
step c).
3. The process according to claim 1, wherein the comminuted product
in step d) is divided into two fractions including a coarse
fraction having particles above 80 .mu.m and a fine fraction having
particles smaller than 80 .mu.m, transferring the fine fraction out
of the process and wherein the coarse fraction is rounded in a
rounding step.
4. The process according to claim 1, wherein the comminuted product
in step d) is divided into three fractions including a coarse
fraction, a fine fraction and a middle fraction having particles
between 80 and 2000 .mu.m, transferring the fine fraction and the
coarse fraction out of the process and wherein the middle fraction
is rounded in a rounding step.
5. The process according to claim 4, including the step of removing
any dust during the rounding step.
6. The process according to claim 1, including the step of coating
the product obtained in step d) with auxiliary substances.
7. The process according to claim 1, wherein the inorganic pigments
are selected from the group consisting of iron oxides, titanium
dioxide, chromium oxides, the mixed phase pigments and mixtures of
these pigments with carbon blacks.
8. The process according to claim 1, wherein the auxiliary
substances are selected from the group consisting of water, salts
selected from among the phosphates, silicates, aluminates, borates;
polysaccharides and cellulose derivatives, oils from biological
cultivation, refined petroleum oils based on paraffins and/or
naphthenes, synthetically produced oils, alkylphenols, glycols,
polyethers polyglycols, polyglycol derivatives, protein fatty acid
condensation products, alkylbenzenesulphonates,
alkylnaphthalenesulphonates, lignosulphonates, sulphated polyglycol
ethers, melamine formaldehyde condensates, naphthalene formaldehyde
condensates, gluconic acid, polyhydroxy compounds or aqueous
solutions thereof.
9. The process according to claim 1, wherein the auxiliary
substances are added in quantities of from 0.001 to 10 wt. %,
referred to the pigments used.
10. The process according to claim 1, wherein the pressing or
briquetting of step b) is carried out by means of a roll press or
matrix press at line forces of from 0.1 to 50 kN/cm.
11. The process according to claim 1, wherein the comminution of
step c) is carried out by screening through a passing screen having
a mesh size of from 0.5 to 4 mm.
12. The process according to claim 1, including a rounding step for
rounding the particles of the first fraction, and wherein the
rounding step is carried out on a rotary disk, in a rotary drum, in
a screening unit or in a fluid bed.
13. The process of using the granular materials produced by the
process according to claim 1 for coloring building materials
including concrete, cement mortar and plasters, and for coloring
organic media including paints, plastics and pigment pastes, and
for producing disperse dyes and slurries.
14. A process for coloring building materials comprising the steps
of mixing briquetted or pressed granular materials produced
according to claim 1 with building material including cement in a
quantity of from 0.1 to 10 wt. %, referred to the cement.
15. A process for coloring organic media comprising the steps of
mixing briquetted or pressed granular materials produced according
to claim 1 with organic media in a quantity of from 0.1 to 10 wt.
%, referred to the organic media.
16. A process according to claim 1, wherein the first fraction has
85% of the particle larger than 100 .mu.m.
17. A process according to claim 1, wherein the first fraction has
85% of the particles between 80 and 2000 .mu.m.
18. A process according to claim 17, wherein the first fraction has
85% of the particles between 100 and 1000 .mu.m.
19. A process according to claim 1, including a rounding step for
rounding the particles of the first fraction.
20. The process according to claim 19, including the step of
removing any dust during the round step.
Description
[0001] The present invention relates to a process for producing
briquetted and pressed granular material and the use thereof for
coloring building materials, such as concrete and asphalt, and
organic media, such as paint systems, plastics and colored
pastes.
[0002] The processing of pigment granules requires that the
pigments be ground to primary particles in order to achieve the
optimal color effect. The resulting powders formed create a large
amount of dust and, owing to their finely-divided state, tend to
adhere and stick in dosing plants. In the case of toxicologically
harmful substances, during the processing precautions must
therefore be taken to avoid danger to humans and the environment
owing to the dust formed. But even in the case of safe, inert
substances such as, for example, iron oxide pigments, avoidance of
irritation due to dust is being increasingly demanded by the
market.
[0003] The aim when handling pigments is accordingly avoidance of
dust and improved dosing as a result of good flow properties, in
order to achieve a color effect of even quality for use in building
materials and organic media. This aim is more or less achieved by
applying granulation processes to pigments. Here pelletizing and
spray granulation are generally used. Compacting processes have
hitherto been less suitable, owing to the limited dispersibility of
the granular material obtained thereby.
[0004] In principle, in the case of pigments the market demands two
diametrically opposing properties for the use of pigment granules:
mechanical stability of the granular material and good
dispersibility. The mechanical stability is responsible for good
transport properties during transport between manufacturer and user
as well as for good dosing and flow properties in the pigments in
use. It is produced by high adhesive forces and is dependent, for
example, on the quantity of binder or even on the compacting
pressure during forming. On the other hand, the dispersibility is
influenced by a thorough grinding prior to granulation (wet
grinding and dry grinding), by the mechanical energy during the
incorporation (shear forces) and by dispersing agents, which
immediately lower the adhesive forces in the dry granular material
during the incorporation into a medium. The use of larger
quantities of dispersing agents in pigments is limited, however,
owing to the cost ratio of additive to pigment. A high proportion
of additive moreover causes a corresponding decrease in the
coloring strength or in the scattering power. As the variations in
coloring strength are generally less than .+-.5%, the use of
additives is also restricted even if these are acting
simultaneously as adhesion promoters and dispersing agents.
Furthermore, the additives must not unfavorably alter the
properties in use of end products such as building materials,
plastics and paints: for example, the strength or the setting
properties in concrete, the compressive strength or abrasion
resistance in asphalt and the strength or the notch impact
resistance in plastics and the elastic properties in elastomers
(polymers).
[0005] Suitable production processes according to prior art for
pigment granules are, for example, spray granulation (spray drying
by disk or nozzle) and pelletizing (mixers, fluid-bed granulators,
disks or drums).
[0006] The spray-drying granulation starts from pigment suspensions
with the use of binders. Relevant processes are described in
various protective rights; here water-soluble binders are used.
Thus in DE-A 3 619 363, EP-A 0 268 645 and EP-A 0 365 046 the
processes start from organic substances such as, for example,
lignosulphonates, formaldehyde condensates, gluconic acids,
sulphated polyglycol ethers, whereas in DE-A 3 918 694 and U.S.
Pat. No. 5,215,583 the processes start from inorganic salts such
as, for example, silicate and phosphate. A combination of spray
granulation and pelletizing has also been described in EP-A 0 507
046. In DE-A 3 619 363 (column 3, lines 44-47) and EP-A 0 268 645
(column 7, lines 18, 19) the use of a compacting process is
adopted. In this process a strong coherence of the particles is
achieved by application of pressure, so that a good
transportability but at the same time decreased properties of
dispersibility are produced.
[0007] In EP-A 0 257 423 and DE-A 3 841 848, spray granulation
using polyorganosiloxanes as hydrophobic, lipophilic additives is
described. The spray-dryer mentioned generally leads to small
particle sizes, that is, to a high proportion of fine material.
This means that a significant proportion of the material is not
obtained from the dryer as immediately usable granular material,
but is first retained as fine material in the filter and has then
to be returned to the process. The aftertreatment carried out to
render the material hydrophobic, in the case of spray-dried
products, results in granular material which flows very well but is
exceptionally dusty.
[0008] EP-A 0 424 896 discloses the production of fine granular
material low in dust, in a production operation in known intensive
mixers. A low content of waxes in combination with emulsifier and
wetting agents is used here by creating an aqueous dispersion. In
the course of this water contents of from 20% up to over 50% are
generally obtained. These granular materials must first of all be
dried and separated from oversize and undersize material.
[0009] DE-A 31 32 303 describes inorganic pigment granules which
are free-flowing and low in dust, which are mixed with binders
renderer liquid by the action of heat and are granulated by a
screening process with the use of a screening aid (pressure). About
10 to 20% of the throughput accumulates as fine material of <0.1
mm.
[0010] EP-A 0 144 940 discloses pigment granules low in dust which,
starting from filtration sludge containing about 50% water, through
the addition thereto of 0.5 to 10% of surfactants as well as
mineral oil or waxes liquefying at 50 to 200.degree. C., are mixed
until lubrication point is reached. The procedure is carried out in
intensive mixers, and if necessary the mixture is granulated and
dried. Water is present in the end product in a quantity of 10 to
15%, which is disadvantageous for introduction into plastics.
[0011] Other processes are also limited in their application. Spray
granulation, owing to the formation of droplets, requires the use
of free-flowing and hence highly fluid suspensions. Consequently,
for the drying process a greater quantity of water has to be
evaporated than from highly pressed-out filtered pigment pastes
during the frequently applicable fluid-bed drying. This leads to
high energy costs. In the case of pigments previously produced by
calcination, spray granulation involves an additional processing
step with high energy costs. Moreover, in spray granulation a
greater or lesser proportion of fine material accumulates, which
has to be returned to the production unit.
[0012] Pelletizing, too, frequently exhibits disadvantages.
Starting from pigment powder, it may be carried out in mixers under
conditions of high turbulence, in the fluid-bed process or else by
disk granulation and drum granulation. Common to all these
processes is that the requirement for binder, in most cases water,
is high, so that drying has to follow as an additional processing
step. Here, too, granular materials of differing size are obtained,
especially if insufficient binder is available for the quantity of
powder or if the actual distribution is not optimal. Then a certain
fraction may be too large for use as granular material, while on
the other hand fractions which are excessively small and hence
dust-forming are still present. A classifying of the granular
material formed is therefore necessary, with oversize and undersize
material being returned.
[0013] Disk granulation leads to granular materials having a wide
particle size spectrum. Where this is undesirable because of the
poor dispersibility of excessively large particles, the granulation
process has to be monitored through intensive supervision by staff
and the production of granular material has to be optimised by
manual control of the quantity of grains. This is generally also
followed by a classification and return of oversize and undersize
material.
[0014] Extrusion processes from pastes lead to the formation of
relatively solid granular materials during drying; owing to their
size, these do not guarantee an optimal dispersibility.
[0015] DE-A 42 14 195 describes a process for coloring asphalt
using inorganic pigment granules, with oils being used as binders.
It is a simple granulation process.
[0016] In DE-A 4 336 613 and DE-A 4 336 612 inorganic pigment
granules are produced from pigments by mixing with binders,
compacting, rough grinding and granulating. The granular materials
thus produced are not transportable satisfactorily by pneumatic
means; during transportation a large quantity of dust is formed,
which is undesirable.
[0017] It was accordingly the object of the present invention to
provide a process which avoids the hitherto described disadvantages
of spray granulation, extrusion granulation or pelletizing in their
application to inorganic pigments and which provides sufficiently
stable granular material which can be dosed, is low in dust and has
a dispersibility as far as possible equally good as that of the
powders used hitherto.
[0018] It has now been found that this object can be met by a
multistep combination of the processing steps mixing, compacting,
separation and optionally rounding.
[0019] The invention provides a process for producing briquetted
and pressed granular material from inorganic pigments and auxiliary
substances, which is characterised in that
[0020] a) one or more inorganic pigments are mixed with one or more
of the auxiliary substances promoting processability,
[0021] b) this mixture is subjected to a pressing or briquetting
step,
[0022] c) this pressed or briquetted product is comminuted,
[0023] d) the comminuted product is divided up into two or more
fractions,
[0024] e) the fraction wherein at least 85% of the particles are
larger than 80 .mu.m, preferably larger than 100 .mu.m, or are
between 80 and 2000 .mu.m, preferably between 100 and 1000 .mu.m,
is removed and optionally rounded in an additional step and the
other fraction or fractions is/are transferred out of the process
or returned.
[0025] Prior to step c) the pressed or briquetted product may be
divided up preferably into two fractions (intermediate step x), in
order then to comminute the coarse fraction, wherein at least 85%
of the particles are larger than 500 .mu.m, preferably 600 .mu.m,
in step c), and to divide the other, fine fraction, once again into
two or more fractions in step d), separate from or together with
the product from step c).
[0026] Preferably only the fine fraction from intermediate step x)
is divided up into two or more fractions in step d), while the
coarse fraction from intermediate step x) is comminuted in step c)
and is then transferred out of the process as product.
[0027] Intermediate step x) may be carried out preferably by
pneumatic classification or screening (mechanical separation).
Preferably screening machines are used.
[0028] The comminuted product in d) is particularly preferably
divided up into two fractions, with the fire fraction smaller than
80 .mu.m being transferred out or returned to the process and the
coarse fraction larger than 80 .mu.m optionally being rounded in an
additional step.
[0029] The comminuted product may also preferably be divided up
into three fractions in step d), with the fine fraction and the
coarse fraction being transferred out of the process or returned to
the process and the middle fraction between 80 and 2000 .mu.m,
particularly preferably between 100 and 1000 .mu.m, most preferably
between 100 and 500 .mu.m, optionally being rounded in an
additional step.
[0030] The granular materials preferably have a residual water
content of less than 4 wt. %, particularly preferably less than 2
wt. %. This can be obtained if necessary by after-drying.
[0031] The rounding step under e) is preferably carried out with
the dust fraction removed.
[0032] The product formed by the rounding in step e) may preferably
in addition be coated with auxiliary substances.
[0033] If a rounding step under e) is carried out, afterwards
preferably a coarse fraction having particle sizes of >1500
.mu.m can be separated and optionally returned to the process.
[0034] The inorganic pigments used are preferably iron oxide,
titanium dioxide, chromium oxide, rutile mixed phase pigments and
mixtures of these pigments with carbon black.
[0035] The inorganic pigment granules have bulk densities
preferably of between 0.5 and 4.0 g/cm.sup.3, particularly
preferably between 0.5 and 2.0 g/cm.sup.3. The granules mixed with
carbon black have bulk densities preferably of from 0.3 to 1.5
g/cm.sup.3.
[0036] Both inorganic and organic substances may be used as
auxiliary substances.
[0037] The auxiliary substances used are preferably water, salts
selected from among the phosphates, carbonates, nitrates,
sulphates, chlorides, silicates, aluminates and borates, formates,
oxalates, citrates and tartrates; polysaccharides, cellulose
derivatives such as, for example, cellulose ethers, cellulose
esters, phosphonocarboxylic acids, modified silanes, silicone oils,
oils from biological cultivation (for example, rape oil, soy bean
oil, maize oil, olive oil, coconut oil, sunflower oil), refined
petroleum oils based on paraffins and/or on naphthenes,
synthetically produced oils, alkylphenols, glycols, polyethers,
polyglycols, polyglycol derivatives, protein fatty acid
condensation products, alkylbenzenesulphonates,
alkylnaphthalenesulphonates, lignosulphonates, sulphated polyglycol
ethers, melamine formaldehyde condensates, naphthalene formaldehyde
condensates, gluconic acid, polyhydroxy compounds or aqueous
solutions thereof.
[0038] In addition, during mixing preferably emulsifiers, wetting
agents and dispersing agents may be added in a quantity of from
0.01 to 5 wt. %, preferably from 0.01 to 3 wt. %, referred to the
weight of the pigment used.
[0039] Suitable emulsifiers are in particular emulsifiers having
HLB values of 7 to 40, particularly 8 to 18, for use in building
materials containing aqueous systems, such as concrete, and
consisting of alkyl or acryl groups and hydrophilic intermediate
and end groups such as, for example, amides, amines, ethers,
hydroxyl, carboxylate, sulphate, sulphonate, phosphate, amine salt,
polyether, polyamide, polyphosphate. The substances may be used,
according to their HLB value, individually or in combination.
[0040] Suitable wetting agents are in particular
alkylbenzenesulphonates, fatty alcohol sulphates, fatty alcohol
ether sulphates, fatty alcohol ethoxylate, alkylphenol ethoxylate,
alkane sulphonates, olefin sulphonates.
[0041] Preferably melamine sulphonates, naphthalene sulphonates,
metal soaps, polyvinyl alcohols, polyvinyl sulphates,
polyacrylamides, fatty acid sulphates are used as dispersing
agents.
[0042] To increase the stability or to assist in the processing of
the granular material it may be beneficial finally to coat the
granular materials with an additional layer. This layer can be
produced by applying inorganic salts in solution, polyols, oils or
waxes or polyethers, polycarboxylates or cellulose derivatives,
preferably carboxymethyl celluloses.
[0043] Preservatives may also be added to the granular materials
during mixing, in a concentration of from 0.01 to 1 wt. %, referred
to the weight of the pigment. Examples which may be mentioned are
formaldehyde-releasing compounds, phenolic compounds or
isothiazolinone preparations.
[0044] Surprisingly, auxiliary substances for the pressed and
briquetted granular materials, in particular if these are intended
for incorporation into aqueous building materials systems such as
cement mortar or concrete, can be not only water-soluble substances
but also substances insoluble in water such as, for example,
oils.
[0045] The auxiliary substances are added preferably in quantities
of from 0.001 to 10 wt. %, particularly preferably from 0.01 to 5
wt. %, most preferably from 0.1 to 3 wt. %, referred to pigment
used.
[0046] The auxiliary substances can be added preferably compounded
with other additives such as, for example, wetting agents, metal
soaps, et cetera.
[0047] The pressing or briquetting step b) is preferably carried
out by means of a roll press or matrix press and preferably at line
forces of from 0.1 to 50 kN/cm, preferably 0.1 to 20 kN/cm.
[0048] In the pressing or briquetting (compacting, step b)) an
important value is the pressing force (kN) per cm of roll width
(line force). During compacting between rolls, a linear transfer of
the pressing force is assumed, as a pressing surface cannot be
defined and therefore a pressure (kN/cm.sup.2) cannot be
calculated.
[0049] The compaction is preferably carried out at low line forces.
The line forces applied are in general preferably within the lower
range of the commercially available equipment, between 0.1 and 50
kN/cm is preferred. The line forces are most preferably from 0.1 to
20 kN/cm. An example of commercially available equipment is the
Pharmapaktor 200/50 from the firm Bepex GmbH,
Leingarten/Germany.
[0050] The additional separating step x) is carried out preferably
using screening machines such as, for example, drum screens,
oscillating screens and vibrating screens.
[0051] The comminution can be effected by means of all the
conventional commercial comminution units, such as crushers,
toothed roll crushers, rolls equipped with frictional devices and
screen granulators.
[0052] The comminution step c) is carried out preferably using
screen granulators or screen-type mills, wherein the material is
pressed through a passing screen having a mesh size of from 0.5 to
4 mm, particularly preferably from 0.5 to 2.5 mm, most preferably
from 1 to 2 mm (so-called crushers). As is generally known, the
motion of the rotors is circulating or oscillating, at a peripheral
speed of from 0.05 m/sec to 10 m/sec, preferably from 0.3 to 5
m/sec. The distance between rotor and screen or breaker plate is
from 0.1 to 15 mm, preferably from 0.1 to 5 mm, most preferably
from 1 to 2 mm.
[0053] An example of the comminuting equipment which can be used is
the Flake Crusher from the firm Frewitt, Fribourg/Switzerland.
[0054] After the comminution, the fine material smaller than 80
.mu.m is separated off. The quantity of this fine material is
preferably from 10 to 50 wt. %, particularly preferably 10 to 30
wt. %. The fine material is preferably returned to step b). The
remaining fraction is free-flowing, can be dosed, is stable, low in
dust and readily dispersible. A further optimization can be
achieved by additional rounding.
[0055] The rounding step e) is preferably carried out on a rotary
disk, in a rotary drum or drage drum, drum screens or similar units
or in a fluid bed or in a screening plant. Here the dust fraction
can be removed preferably by suction or, in the fluid bed,
transported away with the air.
[0056] One of the advantages of the process according to the
invention is that it is possible to start from dried and if
necessary ground pigment powders. This is in particular especially
economic when the pigment is produced by calcination. In the case
of spray granulation, for example, a further slurrying and
thereafter an additional drying step are necessary. It is moreover
very expensive as regards energy to evaporate off again the water
used for slurrying.
[0057] The process according to DE-A 4 336 613 or DE-A 4 336 612
leads, through pelletizing on the rotary disk, to round particles
which are however inhomogeneous. They consist of a compact core and
an external layer or layers formed thereon, which can become
abraded. These products consequently form dust, especially when
transported pneumatically, and the flow properties are not
particularly good. The products obtained by the process according
to the invention do not have these disadvantages, as they consist
of homogeneous compact particles of uniform density and
strength.
[0058] The granular materials produced by the process according to
the invention are used for coloring building materials such as, for
example, concrete, cement mortar, plasters and asphalt, and for
coloring organic media such as paints, plastics and pigment pastes
and for producing disperse dyes and slurries.
[0059] The granular materials produced according to the invention
are particularly suitable for incorporation into dry cement mortar
mixtures and into plasters.
[0060] In the multistep process according to the invention it is
important that in the first step a sufficiently cohesive
homogeneous material is produced by adding the auxiliary substance
in a mixer. The briquetting or pressing then takes place in the
second step.
[0061] The invention also provides a process for coloring building
materials such as concrete or asphalt using inorganic pigments,
which is characterised in that inorganic briquetted or pressed
granular materials made from inorganic pigments and auxiliary
substances, which have been produced by the process according to
the invention, are mixed with the building material in a quantity
of from 0.1 to 10 wt. %, preferably 1 to 5 wt. %, referred to
cement.
[0062] Another preferred use of the granular materials produced
according to the invention is in disperse dyes and slurries.
[0063] The invention further provides a process for coloring
organic media such as paint systems, plastics and pigment pastes
using inorganic pigments, which is characterised in that inorganic
briquetted or pressed granular materials made of inorganic
pigments, which have been produced by the process according to the
invention, are mixed with the organic medium in a quantity of from
0.1 to 10 wt. %, referred to organic medium.
[0064] The test of the dispersibility in building materials is
carried out in cement mortar by the following method by measurement
of the coloring strength on prisms produced from white cement:
[0065] Cement-quartz sand ratio 1:4; water-cement value 0.35; level
of pigmentation 1.2%, referred to cement; mixer used, obtained from
RK Toni Technik, Berlin, having 5 l mixing tub, structural type
1551, speed of rotation 140 rev/min; batch: 500 g cement. After 100
s, 3 samples of mixture (300 g) are taken and test pieces
(5.times.10.times.2.5 cm) are prepared under pressure (300 bar).
Curing of the test pieces: 24 hours at 30.degree. C. and 95%
atmospheric humidity with subsequent drying for 4 hours at
60.degree. C. Color data measurement by Dataflash 2000, Datacolor
International, Cologne, 4 measuring points per stone, per pigment
mixture 12 measuring points. The average values obtained are
compared with the values of a reference sample. The color
difference E.sub.ab and the coloring strength (reference
sample=100%) were assessed (DIN 5033, DIN 6174). The dispersibility
is described as good at a difference in coloring strength of up to
5% compared with the reference sample, and as satisfactory at a
difference of up to 10%.
[0066] The dispersibility in asphalt was tested by the following
method:
[0067] The pigment/granular pigment together with a road bitumen of
the type B 80 (commercial product from Shell AG) and aggregates is
mixed in a heatable laboratory mixer (Rego mixer) at 180.degree. C.
for 60 seconds. Test pieces are prepared from the mixture by
Marshall's method ("The Shell Bitumen Handbook, Shell Bitumen U.K.,
1990, pages 230-232). Differences in shade in the Marshall test
pieces are assessed calorimetrically against a preset comparative
sample (Minolta Chromameter II, standard illuminant C, Cielab
System, DIN 5033, DIN 6174) by comparison of the red values a*.
Differences in the a* values of less than 0.5 units are
indistinguishable visually.
[0068] The flow properties were tested by assessing the behavior on
discharge from a funnel of 100 ml in volume and having a 6 mm
opening, in accordance with ASTM Test D 1200-88. If the material
flows freely, the flow properties are described as good. If a flow
of material does not take place or does so only after tapping, the
flow properties are considered to be inadequate.
[0069] The determination of the fine material as screen oversize is
carried out on a VA screen in accordance with DIN 4188, having 80
.mu.m mesh size on an air-jet screening machine of the type Alpine
200 LS. 20 g of the sample to be tested is used. The fine material
is removed by suction for a running time of 5 minutes and the
quantity of coarse fraction on the screen is reweighed.
[0070] The dispersibility of plastics is determined in accordance
with a test in DIN 53 775, part 7: "Testing of coloring materials
in plasticized polyvinyl chloride (PVC-P) materials; determination
of the dispersing hardness by two roll milling": The pigment to be
tested is dispersed in PVC on a mixing roll at 160.+-.5.degree. C.
The rolled sheet obtained is divided and one half is then exposed
to increased shear forces by rolling at room temperature. The
measure of the dispersibility in the case of colored pigments is
the color difference .DELTA.E in accordance with CIELAB (DIN 5033,
6174) between hot- and cold-rolled PVC sheets, and in the case of
white pigments is the difference of the standard tristimulus values
Y (DIN 5033) between hot- and cold-rolled PVC sheets. A readily
dispersible pigment can be dispersed even at low shear forces,
whereas the increased shear forces on rolling at low temperature
are required in order to disperse a relatively indispersible
pigment. The rule is therefore, the smaller the color difference
.DELTA.E or the difference in the standard tristimulus values Y,
the better does the pigment disperse. The dispersibility is of
great importance particularly in the case of granular materials, as
the particles of granular material to be dispersed in the plastics
material have first of all to be divided. For granular materials a
dispersibility is sought which is as good as that of the
corresponding pigment powders, so that the characteristic values
.DELTA.E or Y for powders and granular material should not differ
greatly.
[0071] The measurement of fine dust particles for determining the
stability of granules is carried out in accordance with DIN 55992.
The dust-forming properties of the granules can be determined using
a Heubach "Dustmeter". The quantity of fine dust particles issuing
from a rotating drum, through which a stream of air of a specific
intensity is passed is determined gravimetrically by means of a
glass fibre filter. By carrying out measurements after varying
periods of exposure the progress of the formation of dust can be
determined as a function of mechanical stress.
[0072] The present invention is explained in more detail below by
means of Examples, but should not be regarded as limited
thereby.
EXAMPLE 1 (COMPARISON)
[0073] 50 kg of iron oxide red Bayferrox 130 (commercial product of
Bayer AG) was mixed with 1% of lignosulphonate and 1% of machine
oil of 100 in a mixer for 10 minutes. The mixture was pressed on a
compactor 200/50 (firm Bepex, Leingarten) at ca. 10 kN (2 kN/cm)
and then comminuted on a crusher (firm Frewitt, Fribourg,
Switzerland) by means of a screen of 1.5 mm mesh size. The
proportion larger than 80 .mu.m was ca. 95%. The dispersibility in
concrete, compared with the starting powder, was 100%. The bulk
density was 1.07 g/cm.sup.3. The material forms a large amount of
dust and does not flow out of a funnel having a 6 mm opening.
EXAMPLE 2
[0074] 0.6 kg of the rough-ground (see Example 1) and subsequently
screened material (coarse fraction through a screen having a mesh
size of 300 .mu.m) was rounded in a fluid bed. The apparatus used
is a glass tube of 90 mm in diameter and 665 mm in height equipped
with a fritted-glass filter G 0 as an air diffuser. The quantity
added (4% of the proportion smaller than 80 .mu.m) is swirled by a
quantity of air of 22 Nm.sup.3/h for 10 minutes and 30 minutes
respectively. The material abraded off is discharged by a stream of
air. 20% and 30% of the material respectively was discharged as
fine material. The dispersibility in cement mortar, at a relative
coloring strength of 95% and 94% respectively, is good. The
material flows well. The dust fraction is very small (dust
measurement using the Heubach Dustmeter in accordance with DIN 55
992), the bulk density is higher than that of the starting
material. 100% of the material is larger than 125 .mu.m, as shown
by a control screening. The average particle size is ca. 600 .mu.m.
The quantity separated off as fine material is 34% and 42%
respectively.
EXAMPLE 3
[0075] 1 kg of the material, after comminution by the crusher (see
Example 1) is placed in a drum screen of 220 mm in diameter, 310 mm
in length and having a mesh size of 300 .mu.m, operating at 10
revolutions per minute (rev/min), which is contained in a closed
housing. Suction is applied at the top of the housing, which is ca.
35 l in volume. After a running time of 10 minutes and 30 minutes
respectively, 30% and 37% respectively are removed by suction. The
material of irregular shape exhibits distinct rounding.
Dispersibility and flow properties are good. The tendency to form
dust is low. A further rolling (after-rounding) on a rotary disk
(40 cm diameter, 42 rev/min, 470 inclination) brings no further
improvements.
EXAMPLE 4 (COMPARISON)
[0076] The rough-ground material (see Example 1) is subsequently
rolled by after-rolling for 15 minutes on the rotary disk (40 cm in
diameter, 42 rev/min, 47.degree. inclination) under suction. The
yield is 95%. The dispersibility is good. The material flows well.
The proportion larger than 80 .mu.m is 100%. However the formation
of dust in the dustmeter, at ca. 300 mg, is very poor. In
comparison, the dust values of the granular materials from Example
2 and Example 3 in the dustmeter are ca. 100 mg.
EXAMPLE 5
[0077] 250 g of Corasol C30 carbon black (a Degussa trade product)
respectively 250 g of Monarch 800 carbon black (a Cabot Corp. trade
product) and 250 g of Bayferrox 330 iron oxide black (a Bayer AG
trade product) were mixed for 18 minutes in a mixer with ammonium
lignosulphonate and V 100 machine oil in different quantities. The
mixture was moulded once or twice using various linear forces in a
compactor of type WP50N (from the Alexanderwerk in Remscheid) and
then comminuted in an RFG fine granulator (from the Alexanderwerk
in Remscheid) using a screen with a mesh size of 1.5 mm. The
comminuted product was separated into two fractions using a screen
with a mesh size of 250 .mu.m. The fraction larger than 250 .mu.m
was tested and displayed good flowability (the corresponding powder
mixture had poor flowability). The remaining data for the fraction
and the starting powders are contained in Table 2. The relative
color intensity was measured in comparison with a corresponding
mixture of the starting powder.
1TABLE 1 Dust Dis- measure- charge Bulk Screen Yield Dispers- ment
time density analysis Sample Comments on sample [%] ibiity* [mg]
[s] [g/cm.sup.3] > 80 .mu.m Example 1 pressed and 100 100 --
does not 1.07 95 comminuted flow Example 2 screened: 10 min. in 66
95 104 32 1.14 100 the fluid bed screened: 30 min. in 58 94 85 32
1.17 100 the fluid bed Example 3 10 min. through 70 96 95 32 1.10
100 drum screen 30 min. through 63 94 71 30 1.11 100 drum screen 10
min. through 70 95 96 30 1.11 100 drum screen plus 15 min. rolling
on rotary disk Example 4 not screened, 15 min. 95 98 304 29 1.22
100 rolling on rotary disk *in cement mortar; rel. color intensity
[%]
[0078]
2 Rel. color intensity in Linear force Bulk density Outflow time
concrete Additives [kN/cm] [g/ml] Yield [%] [sec.] [%] Monarch 800
carbon black powder -- -- 0.20 -- non-flowable 100 Bayferrox 330
Monarch 800 2% LS + 7 0.6 61 34 83 50:50, granules 1% oil Corasol C
30 carbon black powder -- -- 0.40 -- non-flowable 100 Bayferrox
Corasol 8% LS + 5 0.6 54 31 96 50:50; granules 1% oil Bayferrox 330
iron oxide powder -- -- 0.7 -- non-flowable 100 LS - ammonium
lignosulfonate oil - machine oil V 100
* * * * *