Note: Descriptions are shown in the official language in which they were submitted.
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Piment preparations of nasty or gellike consistency
The present invention relates to pasty or gellike pigment preparations for
colouring
lime-bound and/or cement-bound building materials, asphalt, paints, varnishes,
paper
or plastics and also to a method of preparing them.
The increase in coloured design in our surroundings over recent decades has
produced a
sharp rise in the use of pigments. Since many coloured materials include at
least a
proportion of inorganic pigments, the demand for these, too, has steadily
risen.
Inorganic pigments are nowadays encountered in numerous areas of everyday
life. They
are used, for example, for colouring building materials such as concrete and
asphalt,
emulsion paints, varnishes, paper and plastics. Iron oxide pigments, nowadays
in
volume terms the largest group among the inorganic chromatic pigments, have
been
used since prehistoric times. The cave paintings at Altamira (Spain) and
Lascaux
(France), which are around 15 000 years old, provide evidence of the use of
naturally
occurring iron oxide as a pigment. The ancient Egyptians, Greeks and Romans
too used
naturally occurring iron oxide pigments as colorants. For a long time now the
natural
occurrence has no longer been able to cover this demand, particularly in view
of the
continual and ongoing increase in the qualitative requirements in terms of the
performance properties. The synthetically produced pigments are significantly
superior
to their naturally occurring counterparts in terms of opacity, brilliance of
colour and
consistency of quality.
In the processing of pigments, achieving the ideal colour requires that the
pigments be
ground down into primary particles. Accordingly the modern production
processes for
pigments usually include such a grinding operation. On account of their finely
divided
nature, however, the resultant pigments are very dusty and tend to adhere to
packaging
and machine components and also when stored in silos. In the case of
toxicologically
hazardous substances, therefore, measures must be taken during processing to
avoid
risks to humans and the environment through dusts that are formed. Even in the
case of
unobjectionable inert substances, however, such as iron oxide pigments, for
example,
the avoidance of dust nuisance is an increasing market requirement.
Supply forms for colouring building materials:
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For the colouring of building materials, such as concrete products, for
example, the
pigments are used primarily in powder form. In their ground form they have the
advantage of ready dispersibility. The complete and homogeneous distribution
of such
pigment powders takes place in the concrete mixer in a short time - generally
within a
few minutes. The disadvantage of these fine powders is that they do not have
good flow
characteristics and frequently clump together and form lumps in the course of
storage.
This hinders precise metering when processing. A further disadvantage of the
powders
is that they tend to form dust.
Avoiding dust and improving metering in the application of pigments for
colouring
building materials is a prime objective. Since the end of the 1980s this
objective has
been achieved more or less by application of granulation methods to pigments.
Examples of such granulation methods include agglomerative granulation and
spray
drying granulation.
Spray drying granulation starts from pigment suspensions to which granule
binders are
added. Granulation by the spray drying method takes place in co-current or
counter-
current flow via single-fluid or dual-fluid nozzles or via atomizing driers,
producing
granules having an average particle size of 50 to 500 m. The corresponding
methods
are described in numerous patents and are known to the skilled person. These
methods
use predominantly water-soluble binders. Thus DE 3 619 363 Al, EP 0 268 645 Al
and EP 0 365 046 Al start from organic substances such as ligninsulphonates,
formaldehyde condensates, gluconic acids and sulphonated polyglycol ethers,
for
example, whereas DE 3 918 694 Al and US 5,215,583 Al teach the possibility of
using inorganic salts as well, such as silicate and phosphate, for example.
More
recently, granulates with water-insoluble binders as well have been proposed.
For
instance, US 6,596,072 B1 and US 6,695,990 B1 add hydrophilic clay binders,
preferably aluminosilicates or puzzolanes. DE 103 19 483 Al discloses a
dispersible
pigment concentrate, used among other things for colouring building materials
such
as concrete, that comprises at least one pigment and also, if desired, binder,
dispersant and wetting agent, and containing a disintegration assistant which
on
contact with water (in sufficient amount) brings about, within one minute, the
substantially complete disintegration of the primary structure of the
concentrate
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without mechanical exposure, releasing the pigment. Disintegration assistants
used
are preferably cellulose fibres with a particle size between 10 and 2000 m.
DE 197 31 698 Al has already disclosed the use of disintegrants in the
production of
granules said to be suitable for colouring building materials or asphalt. A
disintegrant
usually comprises highly hydrophilic polymers having an appropriately great
absorption capacity for water. DE 100 02 559 B4 and DE 100 66 190 B4 as well
have
already disclosed the use of disintegrants in granule production.
Owing to the drop formation stage, spray granulation requires the use of
highly fluid, in
other words highly mobile, suspensions. Since the drying operation involves
evaporation of a relatively large quantity of water, the method is very energy-
intensive
and therefore unfavourable on grounds of the environment and climate
protection. In
the case of pigments which have been produced by a dry production process,
such as a
calcining process, for example, spray granulation implies an additional step
with high
energy costs, since the pigment already obtained in the dry state must be
suspended in
water again and dried. Moreover, in the case of spray granulation, there is a
more or
less substantial fraction of fine material obtained in the dust filter, which
must be
recycled to the production operation.
Agglomerative granulation can be carried out - starting from pigment powder -
in
mixers with high turbulence, in a fluidized bed method or else in rotary
plates
(pelletizing plates) or rotary drums (pelletizing drums). A feature common to
all of
these methods is the high level of binder required, usually water, with the
consequence
of drying as a necessary additional step. Here again, granules of different
sizes are
obtained, particularly if there is insufficient binder for the amount of
powder, or the
actual distribution is less than optimum. In that case a certain fraction of
the granule
particles may become too large, while on the other hand there are also
excessively
small fra.ctions present which as a result still form dust. It is therefore
necessary to
classify the granules formed, and to return oversize and undersize.
Granulation in a
rotary plate (pelletizing plate) leads to a broad particle size spectrum.
Where this is
unwanted, owing to the poor dispersibility of oversized particles, intensive
use of
operatives is necessary to monitor the granulating operation, and manual
control of the
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amount of seed must be practised in order to optimize granule production. Here
as well,
typically, the product is classified with recycling of the oversize and
undersize.
As well as agglomerative granulation and spray drying granulation the prior
art has also
described other granulation methods. Thus, for example, EP 0 507 046 Al
discloses a
combination of spray granulation and agglomerative granulation. DE 3 619 363
Al and
EP 0 268 645 Al except the application of a compacting method.
In recent years it has also been possible, increasingly, for granules produced
by
briquetting and compression to establish themselves within the market for the
purpose
of colouring building materials. DE 196 38 042 Al and DE 196 49 756 Al
describe
inorganic pigment granules comprising dry pigments, ready-produced product for
example, by blending with one or more auxiliaries, compacting and further
steps such
as comminuting, screening and recycling of oversize and/or fines. The granules
obtained can be enveloped with an additional coat that serves to increase the
stability
and as an aid in processing. These granules have since acquired large-scale
commercial
success in the colouring of building materials. A disadvantage of this method
is that it
starts from dry pigment powders which may have been ground. In other words,
once
again, an energy-intensive production step is required which is unfavourable
on
grounds of environmental and climate protection.
DE 4 336 613 Al describes inorganic pigment granules comprising dry pigments,
ready-produced product for example, by blending with binders, compacting and
further
steps such as treading in a screening granulator, with subsequent
agglomerative
granulation on a rotary plate or in a rotary drum. The pigment granules
produced in this
way are suitable for colouring building materials such as concrete or asphalt.
The
disadvantage already mentioned above in the context of the compression and
bricketting granules applies in this case as well.
The skilled person is aware of further methods of preparing inorganic pigment
granules
suitable for applications including the colouring of building materials.
DE 28 44 710 Al describes the granulation of pigments in a fluid bed with
granulating
assistants, where dry pigment powder is sprayed with water. US 6,758,893 B2
discloses
an extrusion method in which the pigments are mixed with 1% to 25% by weight
of
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water in order to give a moist powder. The moist powder is extruded through a
die
having at least one opening. The granules obtained are dried to a residual
moisture
content of less than 1% by weight, comminuted and screened. The extrusion
granules
prepared by this extrusion method are suitable for colouring concrete. US
6,562,120 B1
describes a very similar method. It involves a combination of an extrusion
method and
compacting method. A moist mixture of pigment and water is extruded through at
least
one die, the mixture being compacted at the same time. Subsequently the
granules are
dried to a residual moisture content of less than 5% by weight. The three last-
mentioned methods are very unfavourable in terms of cost and environmental
protection, since dry pigments are mixed with large quantities of water which
must be
expelled again at a later point in the production process, meaning that, once
again, an
energy-intensive and high-cost drying step is required.
Another dust-free and automatically meterable supply form for pigments for
colouring
building materials, developed at the beginning of the 1980s, is the liquid
colour, also
called a slurry. The pigment is dispersed in water with the aid of a number of
adjuvants.
These adjuvants are essentially wetting and dispersing additives which allow
the
production of liquid colours having a high pigment content coupled to a
relatively low
viscosity. The reason for the relatively low viscosity is to allow the liquid
colour to be
metered effectively. The solids content of the commercially available liquid
colours
generally is not more than 55%. At the same time the wetting and dispersing
additives
are also intended largely to reduce the sedimentation propensity, so that
sufficient
stability - even in the case of a prolonged storage period - is achieved. The
attendant
improvements in comparison to the powder pigment are, essentially, absence of
dust
and greater ease of metering. A further advantage of the liquid colour is
that, through
the dispersing operation involved in producing the liquid colour, the pigments
are at
least partly comminuted into their primary particles. As a result there is a
very quick
development of the full colour strength when the liquid colour is incorporated
into the
building material mix. The liquid colour, however, also has a number of
disadvantages.
In contrast to solid pigment forms such as powder or granules, liquid colour
can be
stored only for a limited time. Over time it tends to separate - that is, the
pigment
settles at the bottom of the containers. This sedimentation produces unwanted
inhomogeneities in the liquid colour, since there is a higher pigment content
at the
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bottom of the container than at the top. For this reason the manufacturers
advise
homogenizing the liquid colours in the event of prolonged storage - and in any
case
before use. For this purpose either the liquid colours can be stirred, or else
compressed
air is blown into the containers, where it swirls and so rehomogenizes the
pigment
suspension. The high water content of the liquid colours represents a problem
particularly in winter at frost temperatures. This makes scheduling and
warehousing
difficult. Another disadvantage of the liquid colour occurs if its containers
become
damaged. The liquid colour leaks out, causing contamination to the environment
and to
employees.
An alternative form of the liquid colour is a liquid colour which is prepared
by the user
itself, by mixing the pigment with water immediately before use, known as an
on-site
slurry. The user obtains pigment powders or granules from the manufacturer,
stirs them
into water on site, and then meters the suspension into its building material
mix. Since
such suspensions generally do not contain further adjuvants they are not
stable to
sedimentation and hence also exhibit constantly non-homogeneous
characteristics
during stirring. This form of liquid colour has receded into the background
over recent
years.
DE 299 10 022 Ul describes thermal carbon black for the black colouring of
cement-
bound building materials. According to the teaching of DE 29910 022 U1 it is
advantageous to use an aqueous liquid suspension (slurry) rather than a powder
or
granule. WO 0 1/55050 discloses a high-viscosity pasty aqueous slurry based on
thermal
carbon black for the black colouring of cementitious articles. The high-
viscosity pasty
aqueous slurries have very high solids contents of more than 50%. In spite of
this they
are to be conveyable using pumps and also to be readily and reliably
meterable. Such
high solids contents, however, have to be stabilized by addition of wetting
agents and
dispersants.
DE 29 08 202 Al describes a method of producing hydrous, non-dusting, readily
dispersible carbon black preparations having a powder like, bead like or
liquid
character, the water content being adjusted so that the preparations contain
between
30% and 80% water. In the production of the carbon black preparations it is
also
possible to use wetting agents and/or dispersants. The carbon black
preparations can be
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used as colorants in the paper, cardboard and cement industries. The
production method
disclosed, however, is not applicable to other pigments.
The commercially available aqueous pigment preparations comprise wetting
agents and
dispersants in order to give suspensions having very high solids contents
while
retaining acceptable viscosities that allow processing. The addition of
dispersants acts
as a plasticizer in the concrete mixes. They retard the solidification of the
concrete, and
also influence the water-cement ratio and have an effect on the concrete's
consistency.
Supply forms for colouringasphalt:
As well as the abovementioned DE 4 336 613 Al; whose description includes that
of a
method of colouring asphalt with inorganic pigment granules, and the
aforementioned
DE 100 03 248 Al, which discloses pigment granules for colouring asphalt,
bitumen,
bituminous substances and tar, DE 42 14 195 Al as well discloses a method of
colouring asphalt with inorganic pigment granules, using oils as binders for
the pigment
granules. This is a simple granulation method. These cases are also subject to
the
abovementioned disadvantages of the granulation methods.
The abovementioned DE 197 31 698 Al discloses the use of disintegrant in the
production of granules which are said to be suitable, among other things, for
the
colouring of asphalt. A disintegrant usually comprises highly hydrophilic
polymers
having a correspondingly great absorption capacity for water. Granules of this
kind
would not disperse quickly enough or well enough in an asphalt mix, since in
the
processing of asphalt there is no water present at all.
Despite the description in the prior art of numerous pigment granules for
colouring
asphalt, and of a multiplicity of production methods, the asphalt industry
still almost
exclusively uses the pigments in a powder form, with all of the attendant
disadvantages.
Granules have not yet become established in this sector.
Liquid colours, on account of their high water content and the hydrophilic
nature of the
asphalt, and also on account of the high processing temperatures, at which the
water
would evaporate and disrupt the production process, are not suited to the
colouring of
asphalt.
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Supply forms for the colouringof emulsion paints and plastics:
DE 4 336 612 Al describes a multi-stage method of preparing inorganic pigment
granules from dry pigments by addition of oils, which is similar to the method
described in DE 4 336 613 Al. The pigment granules prepared in this way are
suitable
for colouring plastics and for producing powder coating materials. The method
disclosed in DE 4 336 612 Al has the same disadvantages already stated with
regard to
DE4336613A1.
Inorganic pigment granules suitable for colouring plastics or varnishes and
also
producing aqueous emulsion paints or tinting pastes are also mentioned in
DE 179 04 943 Al. It describes inorganic pigment granules, intended among
other
things for colouring building materials, vamishes and plastics and for
producing
aqueous emulsion paints, tinting pastes and slurries. The granules comprise
one or
more water-soluble, hydrophilic or hydrophobic/hydrophilic auxiliaries which
are
liquid at 25 C, or mixtures of water-soluble, hydrophilic or
hydrophobic/hydrophilic
auxiliaries, the mixtures being liquid at 25 C, in an amount of 0.1% to 10% by
weight.
For the preparation of these granules there are a variety of preparation
methods
specified, including agglomerative granulation and spray drying granulation
and also a
compacting method.
DE 100 03 248 Al discloses pigment granules for colouring non-polar media such
as
asphalt, bitumen, bituminous substances, tar and plastics, produced from a
mixture
which comprises pigments, at least one agent promoting the colouring and the
distribution of the pigment in non-polar media, and/or at least one dispersant
for polar
systems, and also, where appropriate, solvents. The agent promoting the
colouring and
the distribution of a pigment in non-polar media is to be selected preferably
from the
group of waxes. Like DE 197 04 943 Al, DE 100 03 248 Al also describes a
number
of preparation methods for granules. These methods, however, are only the
methods
already mentioned above, such as compression and bricketting methods,
granulation by
the spray-drying method, fluidized bed granulation or agglomerative
granulation.
As already mentioned, DE 103 19 483 Al discloses a dispersible pigment
concentrate which comprises at least one pigment and also, if desired,
binders,
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dispersants and wetting agents, including a disintegration assistant which on
contact
with water (in sufficient quantity) brings about the substantially complete
disintegration of the primary structure of the concentrate within one minute,
without
mechanical exposure, releasing the pigment. A pigment concentrate of this kind
is
also said to be suitable for colouring plastics and synthetic resins and for
colouring
paints, varnishes and the like. Disintegration assistants used are preferably
cellulose
fibres having a particle size between 10 and 2000 m. Particles of this kind
of size,
however, are unsuitable in the context of producing paints, varnishes and
plastics.
The disadvantage of pigment granules for colouring plastics lies in their
inadequate
dispersibility. For this reason pigment granules have to date been unable to
establish
themselves for the colouring of plastics. The high processing temperatures
experienced during the preparation of plastics can lead to the pigment
granules
sintering together, thereby impairing the dispersing operation. The dispersing
effect
is then no longer sufficient for the production of high-quality plastics.
Liquid colours are unsuited to the colouring of plastics on account of their
high water
content and the hydrophobic nature of the plastics, and also on account of the
high
processing temperatures of the plastics, at which the water would evaporate
and disrupt
the production process.
Pigment granules for the colouring of paints and varnishes are being very slow
to
establish themselves. One of the reasons is the almost infinite variety of
solvent-bome
and solvent-free systems, powder coating materials, and so on. The production
of
granules requires the addition of auxiliaries of some sort. It is known,
however, that
auxiliaries which in one system (combinations of binders, fillers, solvents
and
additives) lead to very good dispersibility or to an improvement in product
properties
may be far less effective in another system, and in certain circumstances an
incompatibility may even be observed. Thus, for example, hydrophobic
auxiliaries
which are advantageous when incorporated into solvent-borne varnish systems
lead to
difficulties when incorporated into aqueous emulsion paints, since the
granules are
wetted only very poorly by water. For this reason, in the field of paints and
varnishes, it
would be necessary to prepare and offer tailor-made granules for every
application
medium, with the auxiliaries optimum for that medium. Only for water-based
systems
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have recent years seen the offering on the market of granules having good
dispersing
properties. Thus, for example, Lanxess Deutschland GmbH, with LEVANYL Gran
and LEVANOX Gran, offers a range of self-dispersing, solvent-free, organic
and
inorganic pigment preparations in microgranular form. These products are
suitable for
numerous water-based systems, such as paints, detergents or jointing mortars,
for
example. The additive fraction in these products, however, is very high. They
are
therefore no longer pure pigment granules, but instead must be considered as
solid
pigment formulations in a ready-to-use form. Similar considerations apply to
the stir-in
pigments from BASF AG which are known under the XfastTM name. These stir-in
pigments are in granulated form and are ready to use, so that the paint is
dispersed
rapidly and uniformly when incorporated with stirring. These products also
have a
very high additive fraction, generally of more than 20% and often indeed up to
30%,
and should therefore also be considered ready-to-use solid pigment
formulations.
They are mostly employed only for water-based paint and varnish systems.
Supply forms for colouring paper:
Even today, powder pigments are still used exclusively for the colouring of
paper. The
reason is that, apart from the powder, all other supply forms contain added
auxiliaries
of some kind. These auxiliaries interfere with the otherwise very demanding
process of
papermaking. For the most part, therefore, the pigments in powder form are
used
directly for paper colouring. In exceptional cases the on-site slurries are
also used,
where the pigment powder is first suspended in water on site before being used
for the
colouring operation.
In principle, the market requires two divergent properties of pigment
granules,
irrespective of the preparation method from which they originate. These two
properties
are as follows: mechanical stability on the part of the granules, and good
dispersing
properties in the medium employed. The mechanical stability is responsible for
good
transport properties both in transit between manufacturer and user, and also
for
effective metering and flow properties when the pigments are used. It is
brought about
by means of high adhesion forces and is dependent, for example, on the
quantity and
identity of the binder. The dispersibility, on the other hand, is influenced
by effective
grinding prior to granulation (wet and dry grinding) by the mechanical energy
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accompanying the incorporation of the pigment into the respective application
medium
(shearing forces), and by dispersing assistants, which immediately lower the
adhesion
forces in the granules when they are incorporated into a medium. Obtaining the
optimum colour requires that the pigment granules be disrupted to form primary
particles. In the case of inorganic pigments, the application of extensive
amounts of
dispersing assistants is restricted owing to the auxiliary/pigment cost ratio.
Moreover, a
high fraction of auxiliaries results in a corresponding reduction in colour
strength
and/or scattering power.
Furthermore, in the case of all supply forms for which auxiliaries of some
sort are
added, such as granules or liquid colour, for example, the additions ought not
to
adversely alter the service properties of the end products they are used to
colour, in
other words building materials, asphalt, plastics, paints and varnishes - for
example, in
the case of concrete, the compressive strength or the solidification
behaviour; in the
case of asphalt, the compressive strength or abrasion resistance; in the case
of plastics,
the strength or notched-impact toughness; in the case of elastomers
(polymers), the
elastic properties; and, in the case of paints and varnishes, the rheological
properties.
It was an object of the present invention, in addition to the known solids
supply forms
for inorganic pigments, such as powders or granules, and in addition to liquid
colour as
a liquid supply form, to provide a completely new supply form for both organic
and
inorganic pigments, this new supply form being dust-free, not having the
disadvantages
of liquid colour, being suitable for colouring a variety of application media,
and
additionally being easy to prepare.
This object has been achieved by means of a pigment preparation for colouring
lime-
bound and/or cement-bound building materials, asphalt, paints, varnishes,
paper or
plastics, comprising
- one or more organic and/or inorganic pigments dispersed in a liquid; and
- if desired, further auxiliaries and/or fillers;
the pigment preparation
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- being of pasty or gellike consistency;
- not tending towards phase separation; and
- not exhibiting any colouring effect on dry and smooth surfaces.
Lime-bound and/or cement-bound building materials for the purposes of this
invention are preferably concrete, cement mortar, plaster and sand-lime brick.
The
generic term asphalt encompasses asphalt, bitumen, all bituminous substances,
and
tar.
The method of ascertaining whether a pasty or gellike pigment preparation that
has
been prepared exhibits no colouring effect on dry and smooth surfaces takes
place with
the aid of a bolt made from bright-drawn V4A round steel (material 1.4571) and
is
elucidated under heading 1.3 in the section concerning the "Description of the
Measuring and Testing Methods used". On dry and smooth skin as well the
pigment
preparation, given a choice of the appropriate thickeners and auxiliaries,
exhibits only a
low colouring effect or, preferably, none at all. The pasty or gellike pigment
preparations can be held and kneaded in the hand. Even under pressure they
exhibit no
colouring effect on the dry internal surfaces of the hand. Any remainders that
do adhere
can be removed easily and generally without residue from the surface in
question. It is
presumed that the intermolecular forces which act within the pasty or gellike
pigment
preparation and are responsible for the formation of the network structures
and/or the
hydrogen bonds in its interior are stronger than the forces of adhesion that
the pigment
preparation is able to develop to smooth and dry surfaces such as metal,
glass, ceramic,
textiles or plastics. The pigment preparation of the invention therefore not
only is dust-
free but also can be handled cleanly and without problems. Only on moist
surfaces
there may possibly be some staining, owing to the beginning of breakdown of
the pasty
or gellike pigment preparation.
One of the features of the pigment preparation of the invention is that one or
more
organic and/or inorganic pigments are in dispersion in a liquid. In this case
it is
possible to use polar liquids or polar liquid mixtures, in other words
mixtures of at
least two polar liquids. The liquid used is preferably water or a water-
miscible liquid
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or a mixture of at least two water-miscible liquids. Since the use of polar
liquids such
as water is disadvantageous when, for example, colouring non-polar plastics or
asphalt, the pigment preparation of the invention may also comprise non-polar
liquids or non-polar liquid mixtures, in other words mixtures of at least two
non-
polar liquids, in which the organic and/or inorganic pigments are in
dispersion. The
liquid used is preferably a water-immiscible liquid or a mixture of at least
two water-
immiscible liquids..
The organic and/or inorganic pigments dispersed in a liquid in the pigment
preparation
of the invention may be both chromatic and achromatic pigments (black pigments
and
white pigments). Inorganic pigments used are preferably iron oxide, titanium
oxide,
chromium oxide, zinc oxide and rutile mixed phase pigments and carbon black
(carbon
pigments) or mixtures thereof. It is also possible, however, to use fillers.
Even the use
of metallic lustre pigments or effect pigments is possible. Organic pigments
used are
preferably azo, quinacridone, phthalocyanine and perylene pigments and
indigoids or
mixtures thereof. The use of one or more inorganic pigments in a blend with
one or
more organic pigments is also conceivable.
The pigment preparation of the invention preferably has a pigment content of
at least
15% by weight, more preferably at least 25% by weight. The maximum possible
pigment content is dependent on the liquid used and on the type of pigment
employed.
A very important part is played by the morphology of the pigment particles and
also by
their size and surface nature. The coarser the pigment, in other words the
larger the
primary particles of the pigment, the higher the maximum possible solids
contents.
Pigment contents of up to 70% or more are possible.
The pigment preparation of the invention is of pasty or gellike consistency. A
pasty
consistency for the purposes of this invention means a very viscous or semi-
solid or
doughy, kneadable or easily deformable mass which does not retain its shape. A
gellike
consistency for the purposes of this invention is a solid and easily
deformable or
kneadable composition which retains its shape.
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The pasty or gellike consistency of the pigment preparation is brought about
preferably
through the addition of at least one thickener and/or at least one thickener
in
combination with one or more compounds which together raise the firmness.
The consistency of the pasty or gellike pigrnent preparation may still change
after it has
been prepared. If the pigment preparation is dispensed immediately after being
prepared
and is not moved anymore for a few days, it often undergoes an increase in its
firmness.
This is possibly because the network structures and/or the hydrogen bonds, and
also
their interplay within the pigment preparation, are able to form only over the
course of
time, and may be disrupted by external mechanical events. For this reason the
consistency of the pigment preparation should be assessed not immediately
after it has
been prepared but instead at the earliest after a 24-hour storage period.
Thickeners used may be both organic and inorganic thickeners. The activity of
thickeners may derive from various effects, such as, for example, swelling,
gelling,
micelle association, solvation, formation of network structures and/or
hydrogen bonds,
and their interplay. The thickeners influence the consistency of the pigment
preparation.
This occurs through the increase in the viscosity, through development of a
gel
structure and also, where appropriate, through a reduction in the surface
tension. It is
preferred to use those thickeners capable of developing a gel structure.
Organic thickeners such as organic natural thickeners, organic modified
natural
materials, organic all-synthetic thickeners, organic associative thickeners or
low
molecular mass organic products are used with preference. The preferred
organic
natural thickeners include, for example, agarose, agar-agar, carrageenans in
the iota,
kappa or lambda form, tragacanth, gum arabic, algin, pectins with a high or
low degree
of esterification, polyoses, guar flour, carubine (carob bean flour), tara
flour, karaya,
gellan, xanthan, starch, starch phosphates, dextrin, gelatines or casein.
Algin should be
considered a collective term for all polysaccharidic constituents from the
cell walls of
brown algae. These include alginic acid and its salts, the alginates, and also
the
derivatives of alginic acid. The commercial products are usually called
alginates.
Agarose or agar-agar, also called just agar for short, comprehends
polysaccharidic
constituents from the cell walls of various red algae. Agar agar is a mixture
of two
fractions: the agarose, which has a gelling effect and is present at up to
70%, and the
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non-gelling agaropectin, at up to 30%. The carrageenan designation comprehends
carrageenan and also the semi-synthetic products which contain only one kind
of ion
and are often referred to as carrag(h)eenates. The three terms are synonymous.
Further details will now briefly be given of some of the preferred organic
natural
thickeners and their properties.
Agar is insoluble in cold water; when heated it dissolves and gels on cooling
in a
similar way to carrageenan, the imaged picture likewise being the formation of
a three-
dimensional network by means of double helices and helical associations. The
gels
acquire their stability solely through hydrogen bonds. Agar gels in just a
0.5% strength
aqueous solution, independently of cations. The gels are stronger than
carrageenan gels
and are thermoreversible. However, they exhibit a very strong hysteresis -
that is, a
difference exists between the softening temperature and the gelling
temperature of the
gel. The gelling point is at 45 C, whereas melting requires heating to 90 C.
In the case of carrageenan a distinction is made essentially between three
main
constituents: kappa, iota and lambda carrageenan. Further carrageenan types,
likewise
identified by Greek letters, such as alpha, beta, pi or omega carrageenan, for
example,
will not be dealt with in any more detail here. In the case of carrageenan the
strength
of the gel is brought about by means of a double helix structure. For kappa
carrageenan and iota carrageenan it is known that the diequatorial glycosidic
linkages
afford the possibility, as hot solutions cool, for the formation of double
helices. In
this way, adhesion zones are formed and a three-dimensional network comes
about: a
gel is formed. On heating, the helices unfold again, to give, once again, a
random
interen tanglement of the molecules: the gel melts. The gels containing
carrageenan
are notable for a low level of hysteresis. In the gel state the helices may
undergo
association with one another: this implies contraction of the network, and the
gel
becomes more brittle and exhibits synaeresis. The water gels produced with
kappa
carrageenan are brittle and tend towards turbidity and synaeresis. This can be
avoided
by means of mixing with iota carrageenan. Iota carrageenan alone forms clear
water
gels which exhibit no synaeresis and have a very low hysteresis but are also
fairly
weak.
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Pectins are high molecular mass glycosidic plant constituents which are
widespread
in fruits, roots and leaves. The pectins are composed essentially of
galacturonic acid
units, with 20% to 80% of their acid groups esterified with methanol. Among
the
pectins a distinction is made between highly esterified pectins, with a degree
of
esterification of more than 50%, and low-esterification pectins, with a degree
of
esterification of below 50%. Quick-gelling pectin (degree of esterification
72% to
74%), normally gelling pectin (degree of esterification 68% to 71%) and slow-
gelling
pectin (degree of esterification 61% to 68%) are differentiated. The gels of
the highly
esterified pectins are not heat-reversible. Low-esterification pectins with a
degree of
esterification of at least 20% require calcium ions for gelling. Calcium
pectinate gels
are heat-reversible.
Guar flour is a colloidal powder, white to greyish white in colour, which is
obtained
by grinding the endosperm of the seeds of Cyamopsis tetragonolobus. As a
hydrocolloid, guar flour swells in water, but without forming a clear
solution, and has
approximately eight times the thickening power of starch. Solutions of guar
flour
have to be preserved.
Carubine (carob bean flour) is the ground endosperm of the seeds of the fruits
of the
carob tree (Ceratonia siliqua). Carubine is a white to whitish grey powder. In
water at
C it is only partly soluble but is fully soluble at 80 to 90 C.
20 Karaya, also called karaya gum, is a white to brownish powder which swells
up to 60
to 100 times its volume in water and forms a viscous mucilage with a strong
bonding
strength. The viscosity of an aqueous karaya suspension is dependent on pH
(not
more than pH 7 to 10) and drops sharply in a more acidic or alkali medium.
The physical and chemical properties of tara flour correspond largely to those
of guar
flour and carubine. Tara flour is not completely soluble in cold water; the
solutions
possess a significantly higher viscosity than solutions of guar flour or
carubine of
equal concentration. Like carubine, tara flour gives gels with xanthan, but
these gels
are weaker and their melting points are lower. Even with agar and carrageenan,
tara
flour exhibits synergistic gel strengthening.
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Gellan gels are stable over a wide temperature and pH range and their firmness
can be
varied by altering the salt concentration. The substituents, too, influence
the gelling
capacity: native gellan, esterified with acetate, forms soft gels, whereas the
gels of
unsubstituted gellan are firm. After heating and cooling, gellan forms
thermoreversible
gels, the presence of monovalent and divalent cations being necessary.
Xanthan is a microbial anionic polysaccharide excreted by Xanthomonas
campestris
under appropriate culturing conditions. In aqueous solution, xanthan takes on
relatively
rigid, regular, helical structures. They may be both single helices and double
helices.
Xanthan dissolves readily in hot and cold water. In that case the helices form
a three-
dimensional network which gives rise to higher viscosities. Xanthans possess
very low
temperature dependency, and stability exists over a wide pH range, from 1 to
11.
Most important representatives of the preferred organic modified natural
substances
include hydroxyethylcellulose, carboxymethylcellulose,
hydroxypropylmethylcellulose,
hydroxypropylcellulose, ethylhydroxyethylcellulose or other cellulose ethers.
Their
thickening effect in water is achieved through hydration, formation of
intermolecular
and intramolecular hydrogen bonds, and interentanglement of the molecule
chains.
Preferred organic all-synthetic thickeners may be polyvinyl alcohols,
polyacrylic acids
and polymethacrylic acids and their salts, polyacrylamides,
polyvinylpyrrolidone,
polyether glycols, styrene-maleic anhydride copolymers and also their salts.
The
polyacrylic acids and polymethacrylic acids and their salts also include the
copolymers
and terpolymers of acrylic acid and methacrylic acid. These thickeners are
available in
the form of an aqueous solution or an acidic emulsion and undergo transition
to highly
viscous solutions only when neutralized.
Preference is also given to organic associative thickeners. These differ from
the
abovementioned organic modified natural materials and the organic all-
synthetic
thickeners in that as well as water-solubilizing hydrophilic groups they also
contain
hydrophobic end groups or side groups in the molecule. This gives associative
thickeners the nature of surfactants, and an ability to form micelles.
Examples of
associative thickeners that may be mentioned include the following:
hydrophobically
modified polyacrylates, which contain non-ionic hydrophilic and hydrophobic
groups
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incorporated into an anionic acrylate thickener molecule; hydrophobically
modified
cellulose ethers, which contain long-chain alkyl epoxides or alkyl halides
incorporated
into a cellulose ether molecule; hydrophobically modified polyacryamides;
hydrophobically modified polyethers; or associative polyurethane thickeners,
which are
composed of hydrophilic polyether segments, linked via urethane groups and of
relatively high molecular mass, which are capped with at least two terminal
hydrophobic molecule groups. The associative thickeners can be used with
advantage
in particular when there are hydrophobic, water-immiscible liquids present in
the
pigment preparation of the invention. Examples of preferred organic products
of low
molecular mass which may act as thickeners are metal soaps, hydrogenated
castor oil,
modified fatty derivatives or polyamides. Preferred metal soaps are metal
soaps derived
from organic carboxylic acids having 8 to 22 carbon atoms and preferably
having 12 to
18 carbon atoms, such as zinc stearate, magnesium stearate, lithium stearate,
zinc
laurate or magnesium myristate.
Thickeners used are preferably inorganic thickeners. Preferred inorganic
thickeners
may be, for example, silicas or polysilicas. For aqueous or hydrophilic
systems
suitability is also possessed by phyllosilicates, which in water, in the
presence of
sufficient shearing forces and in a suitable pH range, lead to the
construction of pasty or
gellike structures. The most important subgroup of the phyllosilicates are the
smectites,
with the subgroups montmorillonite and hectorite. By treatment with quatemary
ammonium compounds, hydrophobic organophyllosilicates are formed from
hydrophilic smectites, and are then suitable for organophilic systems.
Organophyllosilicates can be used with advantage particularly when hydrophobic
and
water-immiscible liquids are present in the pigment preparation of the
invention.
Preference is given to using two or more thickeners which in combination with
one
another possess a synergistic effect and reinforce their thickening action.
Examples of
thickeners which in combination with one another possess a synergistic effect
include
only the combinations of xanthan with dextrin and, in particular, with
galactomannans,
such as carubine, guar flour and tara flour, for example. With carubine, for
example,
xanthan forms strong, rubber like and thermoreversible gels. It is assumed
that in the
case of xanthan, similar to what is the case with carrageenan and agar, a
double helix
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structure is developed which is responsible for the pronounced plasticity and
yield
point. By means of the smooth segments of galactomannan molecules, the double
helices are connected to form a three-dimensional network. Of particular
interest is the
synergistic effect between kappa carrageenan and carubine. If part of the
carrageenan is
replaced by carubine, which itself does not gel, the gel then becomes stronger
and its
properties are improved: it becomes more elastic and has much less of a
tendency
towards turbidity and synaeresis. Agar too shows a synergism with carubine.
It is possible to raise the firmness of the pigment preparation with its pasty
or gellike
consistency by adding one or more compounds. Preference is given to using at
least
one thickener in combination with one or more compounds which together raise
the
finnness, in an overall amount from 0.001 % to 10% by weight, more preferably
from
0.1% to 5% by weight, based on the pigment preparation. Thus it is known that
numerous polyhydroxy compounds such as polyvinyl alcohols or polysaccharides
such
as carubine, for example, in combination with small amounts of borax or
borates,
tend towards a sharp increase in viscosity and, finally, gelling. This effect
occurs not
only in water but also, for example, in formamide. Among the pectins a
distinction is
made between highly esterified pectins, with a degree of esterification of
more than
50%, and low-esterification pectins, with a degree of esterification of below
50%. In
the case of the highly esterified pectins, there are associations in sub-
regions of the
pectin chain, as a result of formation of hydrogen bonds, thereby forming a
three-
dimensional network. The irregularities in the molecule produce only short
points of
adhesion. Stabilizing them necessitates lowering the activity of the water and
reducing the dissociation. Both are accomplished by addition of sugar
(sucrose, for
example) and acid (fruit acids, for example, such as citric acid or malic
acid). The
higher the degree of esterification, the quicker the pectin tends towards
gelling. Low-
esterification pectins, with a degree of esterification of at least 20%,
require calcium
ions for gelling, which with the carboxyl groups and hydroxyl groups of the
galacturonic acid units, linked by axial-axial bonds, form associations of
chains. The
calcium ions must remain in deficit and should react only slowly with the
pectin
molecule. This slow reaction is achieved by using insoluble calcium salts such
as
citrate or phosphate. Amidated pectins occupy a middle position. They require
calcium ions for gelling, but do not tend towards coagulation in the event of
excess
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calcium. With algin as well, a large part is played by cations in the context
of gelling.
Even small amounts of calcium ions may sharply increase the viscosity, as a
result of
formation of complexes. The sensitivity towards calcium ions in this case is
much
higher than in the case of pectins, probably on account of the higher degree
of
polymerization. The adhesion sites are stronger than in the case of pectin. In
contrast
to pectin, calcium alginate gels are not heat-reversible, even in the absence
of sugar.
In the case of carrageenan, the strength of the gel is brought about as a
result of a
double helix structure. In this case the presence of cations has a very
substantial
influence on the strength of the gel. A kappa-rich carrageenan product mixture
of
0.2% of potassium salt, at concentrations of just 0.5%, produces a solid gel
from
water, with a gelling point of about 40 C and a melting point of about 55 C.
The
strength of the water gel climbs sharply as the potassium ion concentration
goes up.
The addition of sugar likewise increases the gel strength. These additions
increase
not only the gelling temperature but also the melting temperature of the gels;
in any
case, however, the hysteresis, in other words the difference between the
softening
temperature and the gelling temperature of the gel, remains low and is between
10
and 15 C.
Thickeners used are preferably algal extracts such as agar agar, carrageenans
in the
iota, kappa or lambda form, alginates such as sodium alginate or calcium
alginate,
exudates of microorganisms or plants, such as xanthan and its derivatives,
gellan,
gum arabic, tragacanth, karaya gum or ghatti gum, endosperms of the seeds of
fruits
or plants, such as guar flour, carubine or tara flour, fruit extracts such as
pectins,
thickeners of animal origin such as protein derivatives and gelatines from
cattle, pigs,
fish and also caseinates, or mixtures of these compounds.
The compound or compounds used which in combination with at least one
thickener
together raise the firmness is or are, respectively, preferably carbonates,
hydrogen
carbonates, sulphates, glycerol phosphates, borates, chlorides, nitrates,
phosphates,
acetates, hydroxides of monovalent, divalent or trivalent metal salts and also
the salts of
a-hydroxy acids (citrates, tartrates, lactates and malates) or of fruit acids
or else the
salts of amino acids (aspartate, arginate, glycocholate and fumarate) and
preferably salts
of the alkali metals and alkaline earth metals, particularly sodium,
potassium,
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magnesium; calcium or strontium salts, preferably sodium nitrate, potassium
nitrate,
magnesium nitrate, calcium nitrate, strontium nitrate, sodium borates,
potassium
borates, calcium borates, magnesium borates, sodium chloride, potassium
chloride,
magnesium chloride, calcium chloride, strontium chloride, sodium sulphate,
potassium
sulphate, magnesium sulphate, calcium sulphate, calcium phosphate, magnesium
acetate, calcium acetate or mixtures of these salts. The amount of the
compound or
compounds is situated preferably in the range from 0.001% to 3% by weight and
more
preferably in the range from 0.1% to 1.5% by weight, based on the total weight
of the
pigment preparation.
Not only salts can raise the fmmness in combination with a thickener. The same
effect
is also known of molecular compounds: consequently it is also preferred to use
molecular compounds which in combination with a thickener raise the firmness.
As
already mentioned, highly esterified pectins may form a three-dimensional
network by
means of hydrogen bonding. The irregularities in the molecule, however, mean
that the
adhesion sites are short. Additional stabilization may be achieved through the
addition
of sugar (for example sucrose). In the case of carrageenan gels as well, sugar
can be
added to increase the gel strength. Agarose gels likewise obtain their
stability solely
through hydrogen bonds. Additional stabilization is achieved, for example, by
crosslinking with 2,3-dibromo-l-propanol.
As compounds which in combination with a thickener raise the firmness it is
possible
to use not only salts and molecular compounds but also complex compounds of
metals.
Preference is given to using complexes of elements of transition groups IV to
VI of the
Periodic Table of the Elements, more particularly of titanium, vanadium and
chromium.
The amount of the compound or compounds which in combination with a thickener
raise the firmness is situated preferably in the range from 0.001% to 3% by
weight,
more preferably in the range from 0.1 % to 1.5% by weight, based on the total
weight of
the pigment preparation.
Thickeners used are preferably fully hydrolysed polyvinyl alcohols and also
their
derivatives or other polyhydroxy compounds in combination with boron
compounds,
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preferably ortho-boric acid, tetra-boric acid, meta-boric acid or their salts,
or in
combination with salts or complexes of elements of transition groups IV to VI
of the
Periodic Table of the Elements, preferably of titanium, vanadium and chromium,
such
as titanium(III) salts or titanium(IV)-triethanolamine, where appropriate with
the pH set
to neutral or slightly alkaline. As well as the various boric acids or their
salts, and also
boric anhydride or fluoroboric acid, preference is also given to organic boron
compounds such as boric esters or complexes of boron trifluoride with, for
example,
dimethyl ether, propanol or acetic acid.
The regularly arranged hydroxyl groups in the polyvinyl alcohol chains are
capable
with certain substances of forming complex compounds or associations which in
chemical terms are more or less stable and which, depending on the
concentration in
which they are admixed, increase the viscosity of the polyvinyl alcohol
solution
possibly even as far as gelling. The classic example of complex formation with
polyvinyl alcohol is its reaction with boric acid on the one hand and with
salts of boric
acid on the other. The reaction with boric acid produces a monodiol complex.
The
viscosity of solutions of these monodiol complexes depends primarily on the
chain
length and on the degree of hydrolysis of the polyvinyl alcohol. The situation
is
different when a polyvinyl alcohol solution is exposed to salts of boric acid
or to a
solution containing boric acid when the pH is shifted into the alkaline. In
this case, as a
polyelectrolyte, the polyvinyl alcohol-boric acid monodiol complex forms the
polyvinyl
alcohol-boric acid didiol complex, in which two polyvinyl alcohol chains are
linked to
one another via boric acid. For this case, however, structures with ionic
bonding are
conceivable as well. Besides ortho-boric acid, tetra-boric acid, meta-boric
acid or their
salts, or boric anhydride or fluoroboric acid, organic boron compounds can be
used as
well, such as boric esters or complexes of boron trifluoride with, for
example, dimethyl
ether, propanol or acetic acid.
The viscosity of polyvinyl alcohol solutions can be increased not only with
boric acid
and its salts but also with complex-fornling compounds of the elements of the
transition
groups IV to VI of the Periodic Table of the Elements. In certain
circumstances this
increase in viscosity goes as far as the gelling of the solution. In many
cases the
complex which forms can be fixed thermally. With polyvinyl alcohol solution,
the
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titanium(IV)-triethanolamine complex yields highly viscous to gelling
titanium(IV)
complexes. The increase in viscosity induced by this complex is largely
independent of
pH. Similarly, titanium sulphate as well reacts with polyvinyl alcohol
solution to form a
titanium(IV)-polyvinyl alcohol complex. Titanium(III) compounds, vanadium
compounds and chromium compounds, even at low concentrations, bring about
gelling
of the polyvinyl alcohol solution. Organic compounds may likewise lead to an
increase
in the viscosity of polyvinyl alcohol solutions. The acetalization of
polyvinyl alcohol as
well, for example with formaldehyde and acid (as catalyst), can be included in
this
consideration. Small amounts lead to a thickening of the polyvinyl alcohol
solution,
possibly to the point of gelling. Stopping the acetalization reaction with
aqueous alkali
fixes the consistency of the mixture at the point it has reached. Gels can
also be
prepared by acetalizing polyvinyl alcohol with difunctional aldehydes such as
glyoxal
or glutaraldehyde, with acidic catalysis. Polyhydric phenols and related
compounds
such as resorcinol, pyrocatechol, phloroglucinol, gallic acid, salicylanilide
and 2,4-
dihydroxybenzoic acid can form relatively loose complexes (associations) with
polyvinyl alcohols. These associations are thermally reversible - that is, it
is possible to
prepare gels which become liquid at an elevated temperature and resolidify on
cooling.
Surprisingly an increase in viscosity possibly to the point of gelling of the
polyvinyl
alcohol solution occurs with the substances identified above even when one or
more
organic and/or inorganic pigments are in dispersion in the polyvinyl alcohol
solution.
Polyvinyl alcohols or their derivatives are very preferentially suited to
preparing the
pigment preparations of the invention. The pasty or gellike pigment
preparations
prepared, starting from water, with addition of partly or fully hydrolysed
polyvinyl
alcohols in combination with ortho-boric acid, tetra-boric acid, meta-boric
acid or their
salts are distinguished by a number of outstanding performance properties: the
consistency of the pigment preparations can be varied over a very wide range
through
the chain length, the concentration and the degree of hydrolysis (degree of
saponification) of the polyvinyl alcohol and also by way of the amount of
added boric
acid or its salts or of the added complex-forming compounds of the elements of
transition groups IV to VI of the Periodic Table of the Elements. A pigment
preparation
can be prepared which has a very soft, pasty and stringing consistency, or
else a
pigment preparation having a decidedly hard and rubber-elastic consistency.
With
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preference, apart from partly or fully hydrolysed polyvinyl alcohols, use is
also made of
other polyhydroxy compounds in combination with ortho-boric acid, tetra-boric
acid,
meta-boric acid or their salts. Such compounds include, for example,
polysaccharides
based on mannans, galactomannan, such as carubine, polymannuronic acid,
polygalacturonic acid, rhamnose, galactose, galacturonic acid, arabinose,
xylose,
glucuronic acid, mannose, glucose or galactan. It is unimportant whether these
polysaccharides are in the form of linear, branched or highly branched
macromolecules.
The stated polyhydroxy compounds occur in nature, as for example in the seeds
of
Ceratonia siliqua (carubine), Medicago sativa, Gleditsia triacanthus,
Trigonella foenum
graecum, Cyamopsis tetragonolobus (guar flour) or Lupinus albus. They also
occur in
nature in the form of mucilage, as for example in the form of mucilage from
the bark of
Ulmus fulva or in the form of mucilage from Linum usitatissimum or from
Tamarindus
indica. They may also occur in nature in the form of gum, as for example in
the form of
cherry gum (Prunus avium) or gum Arabic.
Many thickeners or gel formers act not only in water but also in other polar
solvents.
For example, highly esterified and low-esterification pectins and also the
alkali metal
salts of pectic acid dissolve not only in water but also in dimethylformamide,
dimethyl
sulphoxide and hot glycerol. Polysaccharides which gel in aqueous solution
with borax
also exhibit this phenomenon in formamide. Gelatine too dissolves in ethylene
glycol,
glycerol and formamide.
Where appropriate the pigment preparation of the invention may also comprise
further
auxiliaries. Auxiliaries used are preferably salts from the group of the
phosphates,
phosphonates, carbonates, sulphates, sulphonates, silicates, aluminates,
borates,
titanates, formates, oxalates, citrates, tartrates, stearates, acetates,
polysaccharides such
as celluloses, cellulose derivatives, such as cellulose ethers or cellulose
esters,
phosphonocarboxylic acids, modified silanes, silicone oils, oils from
biological
cultivation (preferably rapeseed oil, soybean oil, maize germ oil, olive oil,
coconut oil,
sunflower oil), refined petroleum oils with a paraffinic and/or naphthenic
basis,
synthetically produced oils, alkylphenols, glycols, polyethers, polyglycols,
polyglycol
derivatives, ethylene oxide-propylene oxide copolymers, protein-fatty acid
condensation products, alkylbenzenesulphonates, alkylnaphthalenesulphonates,
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lignosulphonates, sulphated polyglycol ethers, melamine-formaldehyde
condensates,
naphthalene-formaldehyde condensates, gluconic acid, polyacrylates,
polycarboxylate
ethers, polyhydroxy compounds, polyhydroxyamino compounds or solutions or
mixtures or suspensions or emulsions of these.
Auxiliaries used are preferably wetting agents and/or dispersing additives
and/or
emulsifiers and/or preservatives and/or defoamers and/or retention agents
and/or anti-
settling agents and/or fragrances.
Suitable wetting agents are preferably alkylbenzenesulphonates, fatty alcohol
sulphates,
fatty alcohol ether sulphates, fatty alcohol ethoxylate, alkylphenol
ethoxylate, branched
and/or unbranched alkanesulphonates or olefinsulphonates, branched and/or
unbranched alkane sulphates or olefm sulphates and sulphosuccinates.
Dispersing additives used are preferably lignosulphonates,
melaminesulphonates,
naphthalenesulphonates, soaps, metal soaps, polyvinyl alcohols, polyvinyl
sulphates,
polyacrylamides, polyacrylates, polycarboxylate ethers, medium- and long-chain
alkane
sulphates or alkanesulphonates or alkane sulphosuccinates, and also medium-
and long-
chain alkane phosphates or alkanephosphonates.
Suitable emulsifiers are preferably emulsifiers having HLB values of 7 to 40,
preferably
of 8 to 18, for use in building materials with aqueous systems such as
concrete, for
example, containing alkyl radicals or acrylic radicals and hydrophilic pendent
groups
and end groups such as, for example, amides, amines, ethers, hydroxyl,
carboxylate,
sulphate, sulphonate, phosphate, phosphonate, amine salt, polyether,
polyamide,
polyphosphate. The substances may be used individually or in combination in
accordance with their HLB value.
Preservatives that may be mentioned include, by way of example, formaldehyde
donor
compounds, phenolic compounds or isothiazolinone preparations. Adding such
preservatives is often advisable, since numerous organic thickeners are
sensitive to
microbial attack and can be stabilized by addition of preservatives.
Furthermore, defoamers are also preferably employed. Defoamers are substances
which
are intended to prevent the formation of foam. They act by forming a closed
film at the
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interface of the pasty or gellike pigment preparation with air, and so allow
the medium
in which degassing/defoaming is desired to develop a relatively small surface
area
within a very short time, with destruction of the gas bubbles, and hence to
form a
relatively low-energy state. Defoamers often derive from natural fats and oils
or else are
petroleum derivatives, modified silicone oils or modified polyethers.
Substances identified as fragrances are all those which have a more or less
strong odour
and stimulate the human sense of smell. Preference is given to using
fragrances which
stimulate the human sense of smell in a pleasing or exciting way. The
preferred
fragrances may be natural, semi-synthetic or all-synthetic origin, the
naturally occurring
fragrances hailing from plant or animal sources. The fragrances can be used
individually or in combination with one another.
The auxiliaries are used preferably in a total amount from 0.001 % to 10% by
weight,
more preferably from 0.05% to 5% by weight, based on the pigment preparation.
The pigment preparation of the invention does not tend towards phase
separation over a
period preferably of at least two months, more preferably at least six months.
In other
words, during this time, the liquid phase does not separate out of the pasty
or gellike
pigment preparation. In the case of a gel this phenomenon is referred to as
synaresis. In
synaresis, the liquid phase comes out of a gel without its structure
collapsing. This is
also referred to as exudation. Accordingly, the pasty or gellike pigment
preparations of
the invention remain unchanged over a period of preferably at least two
months, more
preferably at least six months. The method of ascertaining whether a pasty or
gellike
pigment preparation that has been prepared tends towards phase separation by
separating out the liquid phase is elucidated under heading 1.4 in the section
concerning
the "Description of the Measuring and Testing Methods used".
The pigment preparation of the invention exhibits no colouring effect on dry
and
smooth surfaces, such as metal, glass, ceramic or plastics, for example. As
elucidated
under heading 1.3 in the section concerning the "Description of the Measuring
and
Testing Methods used", the average increase in mass of the bolt is preferably
not more
than 0.07 g and more preferably not more than 0.04 g.
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The pigment preparation preferably further comprises at least one filler in an
amount of
not more than 40% by weight, preferably not more than 10% by weight, based on
the
pigment preparation. By fillers are meant colourless inorganic or synthetic,
lamellar or
non-lamellar particles which are able to provide the pigment preparation with
additional thickening and are intended to endow it with hardness, smoothness,
mattness
or lustre. The fillers are preferably selected from talc, mica, silicas,
kaolin, nylon
powders, poly((3-alanine) powders, polyethylene powders, Teflon,
lauroyllysine, boron
nitride, bismuth oxychloride, polytetrafluoroethylene powders, polymethyl
methacrylate powders, polyurethane powders, polystyrene powders, polyester
powders,
synthetic hollow microspheres, microsponges, silicone resin microspheres, the
oxides
of zinc and titanium, the oxides of zirconium and cerium, precipitated calcium
carbonate or chalk, magnesium carbonate, magnesium hydrogen carbonate,
hydroxyapatite, hollow silica microspheres, microcapsules of glass or of
ceramic, metal
soaps derived from organic carboxylic acids having 8 to 22 carbon atoms and
preferably having 12 to 18 carbon atoms, such as zinc stearate, magnesium
stearate,
lithium stearate, zinc laurate and magnesium myristate, the compounds
SiO2/TiO2/SiO2, TiO2/CeO2/SiO2 or else Ti02/ZnO/talc and also the polyethylene
terephthalate/polymethacrylate polymers in the form of platelets.
The invention also provides a method of preparing a pigment preparation,
characterized in that
- to a dispersion of one or more organic and/or inorganic pigments in a liquid
which if desired also comprises further auxiliaries and/or fillers, and
- before, during or after the dispersing operation, at least one thickener
and/or at
least one thickener in combination with one or more compounds which
together raise the firmness is added and
- the pasty or gellike pigment preparation is homogenized for a sufficiently
long
time, and
- where appropriate, finally, further auxiliaries are added.
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By a dispersion is meant, in accordance with DIN EN 862: 1995-10, a system
(disperse
system) made up of two or more phases, of which one is continuous (dispersion
medium) - that is, in the sense of this invention, the liquid or liquids - and
at least one
other is finely dispersed (dispersed phase, dispersoid) - in other words, in
the sense of
this invention, the organic and/or inorganic pigment or pigments. Since
inorganic
pigments are insoluble in liquids, the term "suspension" is to be equated with
that of
"dispersion".
The addition of at least one thickener and/or at least one thickener in
combination
with one or more compounds which together raise the firmness is made
preferably at
room temperature or above room temperature.
Organic or inorganic thickeners are preferably added.
Organic thickeners used are preferably partly or fully hydrolysed polyvinyl
alcohols and
also their derivatives or other polyhydroxy compounds in combination with
boron
compounds, preferably ortho-boric acid, tetra-boric acid, meta-boric acid or
their
salts, or in combination with salts or complexes of elements from transition
groups
IV to VI of the Periodic Table of the Elements, preferably of titanium,
vanadium and
chromium, such as titanium(III) salts or titanium(IV)-triethanolamine, where
appropriate with the pH set to neutral or slightly alkaline.
The pigment preparation of the invention can be prepared either starting from
the dry,
solid pigment or else starting from a liquid phase - a dispersion.
In the former case it is necessary first to disperse one or more organic
and/or inorganic
pigments in a liquid, in order to disrupt the agglomerates of the kind
present, for
example, in pigment powders or granules. The dispersion of one or more organic
and/or inorganic pigments in a liquid is preferably a redispersion of
previously
agglomerated particles. The liquid used is preferably water or a water-
miscible liquid or
a mixture of at least two water-miscible liquids. Since the use of polar
liquids such as
water may be disadvantageous in the case, for example, of the colouring of non-
polar
plastics, it is also possible to use non-polar liquids or non-polar liquid
mixtures, in
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other words mixtures of at least two non-polar liquids. The liquid used is
preferably a
water-immiscible liquid or a mixture of at least two water-immiscible liquids.
The use of dry pigments for preparing the pigment preparation of the invention
is
especially advantageous when the pigments are obtained via a dry production
process.
Thus, for example, titanium dioxide pigments, chromium oxide pigments and
rutile
mixed phase pigments are prepared via calcining processes at high
temperatures. The
preparation of red iron oxide pigments as well may be accomplished by
dewatering of
yellow iron oxide or by oxidation of black iron oxide at high temperatures.
The
dispersing of the solid pigments in a liquid phase may be accomplished, for
example,
by rubbing the pigment between two surfaces or disrupting the pigment
agglomerates
by means of impact forces and shearing forces that are generated by discs in
high-speed
rotation. A combination of these two procedures is also possible. The skilled
person is
aware of all of the dispersing apparatus that operate in accordance with these
principles
and is suitable for the dispersing of solid pigments in a liquid phase.
Mention may be
made at this point merely of roll mills, ball mills, rotor-stator mills,
dissolvers, stirred
mills and compounders. The stirred mills can be operated as bead mills or sand
mills
with beads or sand as grinding media, with only one grinding vessel or else in
the form
of what are called multi-chamber mills or modular mills, with two or more
milling
vessels, usually connected in series. Compounders in the sense of this
invention are all
apparatus for mixing viscous, plastic or solid materials to form tough,
plastic, doughy,
pasty or gellike compositions. The kneading tools of a compounder move
relative to
one another or relative to stationary surfaces in such a way that there is a
high level of
compression, division and lamellar displacement of the material being milled.
The
compounders may be either blade compounders having a double kneading trough
with
z-shaped kneading blades, or planetary compounders, where the kneading arm(s)
or
hook(s) perform planetary movements, or screw compounders with single or
double
screw shafts, or roller compounders. Agitators with a mixing and kneading
attachment
may also be used. It is not critical to the invention whether the dispersing
apparatus
operates continuously or discontinuously. Where appropriate it may also be
advantageous to perform the dispersing operation with the aid of ultrasound.
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Where the starting point is to be a liquid phase, the pigment preparation may
be
prepared starting from an existing pigment dispersion, of the kind obtained,
for
example, immediately after actual pigment synthesis or after filtration and
washing of
the pigment during its work-up and before its drying. The dispersion of one or
more
organic and/or inorganic pigments in a liquid is preferably a dispersion
originating from
the pigment production process.
Numerous inorganic pigments are prepared in aqueous phase. For this reason the
pigment dispersion is preferably an aqueous dispersion from the pigment
production
process. When using a pigment dispersion from the pigment production process
it may
be possible - depending on the point at which the pigment dispersion is taken
from the
pigment production process - to do without the dispersing of the pigment
particles, if
they are already sufficiently well dispersed. In spite of this it may be
advantageous to
employ the dispersing apparatus already mentioned above, if the best possible
dispersing is required. The use of a pigment dispersion from the pigment
production
process is particularly advantageous since it allows the energy-intensive and
cost-
intensive drying of the pigment to be omitted.
When, as a result of the dispersing operation, the organic and/or inorganic
pigment or
pigments is or are sufficiently well dispersed in the liquid, thickening or
gelling takes
place, causing an increase in the viscosity of the composition. Before, during
or after
the dispersing of one or more organic and/or inorganic pigments in a liquid,
at least one
organic or inorganic thickener and/or at least one thickener in combination
with one or
more compounds which together raise the firmness are preferably added - where
appropriate in portions - in a stirrer, mixer, compounder or dissolver. A
large number
of stirrers and stirrer mechanisms is described in the prior art. The skilled
person will
doubtless be able to locate the ideal stirrer or stirrer mechanism for his or
her
application, capable of thorough stirring of pasty or gelatinous compositions
for the
purpose of incorporating, sufficiently well and homogeneously, an organic or
inorganic
thickener and/or at least one thickener in combination with one or more
compounds
which together raise the firmness, into the pigment dispersion as it thickens.
The skilled
person is also aware of a large number of mixers suitable for thorough mixing
of pasty
or gelatinous compositions for the purpose of incorporating, sufficiently well
and
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homogeneously, an organic or inorganic thickener or at least one thickener in
combination with one or more compounds which together raise the firmness, into
the
pigment dispersion as it thickens. Particular preference is given to stirrer
mechanisms
having a mixing and kneading attachment or to compounders capable of thorough
kneading of pasty or gelatinous compositions for the purpose of incorporating,
by
kneading, sufficiently well and homogeneously, an organic or inorganic
thickener
and/or at least one thickener in combination with one or more compounds which
together raise the firmness, into the pigment dispersion as it thickens.
Preferably, following the addition - where appropriate in portions - of at
least one
organic or inorganic thickener and/or of at least one thickener in combination
with one
or more compounds which together raise the firmness, the pasty or gellike
pigment
preparation is homogenized in a stirrer, mixer, kneader or roll mill, where
appropriate
under reduced pressure as well. Operating under reduced pressure allows the
inclusion
of air bubbles to be prevented. In principle the air bubbles possibly included
cause no
disruption when the pigment preparation of the invention is used for colouring
lime-
bound and/or cement-bound building materials, asphalt, paints, varnishes or
paper. In
the case of the colouring of plastics in extruders, in contrast, included air
bubbles can
have a disruptive effect. For this specific application it is particularly
advantageous to
remove the air bubbles beforehand. If the pigment preparation of the invention
is of
pasty consistency, the air bubbles included often rise to the surface in any
case in the
course of a few hours or days after its preparation. In other words, the
pigment
preparation degasses automatically.
The addition of auxiliaries or fillers may in principle be made at any point
in time in the
production process. Preferably they are added at the beginning of the
production
process, in other words before or during the dispersing of the organic and/or
inorganic
pigments in the liquid phase. With preference they can also be added at the
end of the
production process, by incorporating them then into the pasty or gellike
pigment
preparation.
The invention also encompasses a method of colouring lime-bound and/or cement-
bound building materials, asphalt, paints, varnishes, paper or plastics which
is
characterized in that the pigment preparation of the invention is mixed with
the lime-
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bound and/or cement-bound building materials, asphalt, paints, varnishes,
paper or
plastics.
Preferably the pigment preparation, before or during its addition to the lime-
bound
and/or cement-bound building materials, asphalt, paints, varnishes, paper or
plastics
and/or during the operation of mixing with the lime-bound and/or cement-bound
building materials, asphalt, paints, varnishes, paper or plastics, is
liquefied, the
liquefaction taking place by
- dissolution in one or more liquids and/or
- addition of an acid or alkali through a change in pH and/or
- chemical reaction, more particularly redox reactions, or enzymatic reaction
and/or
- supply of heat, mechanical energy and/or ultrasound.
The reliquefication of the pigment preparations of the invention is thus
possible in a
variety of ways. The pasty or gellike pigment preparations prepared starting
from
water with addition of partly or fully hydrolysed polyvinyl alcohols in
combination
with ortho-boric acid, tetra-boric acid, meta-boric acid or their salts
exhibit
outstanding reliquefaction when incorporated into water with stirring. When
the
stirred incorporation is performed in the proper art manner, the preparations
dissolve
in water completely within a short time, usually within just 60 s.
The thickening effect and/or the gelling properties of numerous thickeners are
dependent on the pH. Consequently the pigment preparations of the invention
can
also be reliquefied by addition of acid or aqueous alkali, which changes the
pH. High
acid concentrations and temperatures have the capacity, for example, for
quantitative
decarboxylation of algin and alginate esters.
The reliquefaction of the pigment preparations of the invention can be
accomplished by
means of chemical reaction, preferably redox reactions, or enzymatic reaction.
It is
known that 1,2-glycols can be oxidatively cleaved by exposure to periodate. In
many
polysaccharides this glycol cleavage takes place initially to give the
macromolecules.
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Exposure to potassium periodate then effects the oxidative cleavage of the 1,2-
cis-diol
moiety that is needed for the formation of a complex with borates. In actual
fact, a few
minutes after the addition of potassium periodate to a carubine solution,
addition of
borax produces no further gelling, despite the fact that the viscosity has
fallen only a
very little as a result of oxidative degradation. The carubine, then, is no
longer capable
of gel formation. An existing carubine-borax gel can likewise be reliquefied
by
titration with potassium periodate. The same reliquefaction effect occurs when
solid
sodium periodate is merely scattered onto a carubine-borax gel, or a carubine-
borax gel
is sprayed with a periodate solution. Not only oxidizing agents which act
directly, such
as halogens or periodate, but also redox systems such as polyphenols, ascorbic
acid or
thiol compounds break down algin. To produce alginates of low viscosity,
hydrogen
peroxide is used. Xanthan is broken down by strong oxidizing agents such as
hypochloride or persulphate, particularly at high temperatures. Bacterial
alginic acid
depolymerases have also been described. Numerous other thickeners - especially
when they are of natural origin - can be degraded using enzymes, thereby
losing their
activity.
As already mentioned, numerous gels can be reliquefied by supply of heat. They
are
thermoreversible: that is, it is possible to prepare gels which become liquid
at elevated
temperature and resolidify on cooling. The low-esterification pectins, with a
degree of
esterification of at least 20%, which require calcium ions for gelling, are
heat-reversible
in the form of calcium pectinate gels. After heating and cooling, gellan
likewise forms
thermoreversible gels, the presence of monovalent and divalent cations being
necessary. Xanthan as well forms strong, rubberlike and thermoreversible gels
with
carubine. Polyhydric phenols and related compounds such as resorcinol,
pyrocatechol,
phloroglucinol, gallic acid, salicylanilide and 2,4-dihydroxybenzoic acid may
form
relatively loose complexes (associations) with polyvinyl alcohols. These
associations
are thermally reversible.
Rather than supply of heat, the reliquefaction of the pigment preparations of
the
invention can also be accomplished by supplying mechanical energy, such as by
stirring, for example. The supplying of mechanical energy may be especially
advantageous when it is possible to utilize thioxtropic effects in the context
of the
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pigment preparations of the invention. In certain cases the pigment
preparation of the
invention can also be reliquefied by exposure to ultrasound.
The pigment preparation is preferably mixed with the lime-bound and/or cement-
bound
building materials, asphalt, paints, varnishes, paper or plastics in an amount
from
0.01 % to 15% by weight, preferably from 0.1 % to 10% by weight, based on the
overall
mixture.
The pigment preparation of the invention has a series of advantages. It is
prepared
starting from the liquid phase, thus allowing energy-intensive drying steps to
be
omitted. This is especially advantageous, of course, when the preparation of
the
pigment itself takes place in the liquid phase. The pigment preparation of the
invention
not only is dust-free but also can be handled cleanly and without problems.
Furthermore, it is outstandingly dispersible in the various application media.
On
account of the pasty or gellike consistency, the pigment preparation of the
invention
does not exhibit sedimentation. There is no phase separation, and the
preparation is
stable on storage for a long time period and can be used at any time. It is
therefore
always ready to use. Furthermore, the pigment preparation of the invention
does not
exhibit any colouring effect on dry and smooth surfaces. It is presumed that
the
intermolecular forces which act within such a pigment preparation and are
responsible
for the formation of the network structures and/or the hydrogen bonds in its
interior are
stronger than the forces of adhesion that the pigment preparation is able to
develop to
smooth and dry surfaces such as metal, glass, ceramic, textiles or plastics.
The pasty pigment preparations prepared on the basis of partly or fully
hydrolysed
polyvinyl alcohols and also their derivatives or other polyhydroxy compounds
as
thickeners in combination with boron compounds such as ortho-boric acid, tetra-
boric
acid, meta-boric acid or their salts, or in combination with salts or
complexes of
elements of transition groups IV to VI of the Periodic Table of the Elements,
preferably
of titanium, vanadium and chromium, such as titanium(III) salts or
titanium(IV)-
triethanolamine, where appropriate with the pH set to neutral or slightly
alkali, are
distinguished by further performance advantages. Given a choice of the
appropriate
chain length, the concentration and the degree of hydrolysis of the polyvinyl
alcohol,
and also of the correct amount of boron compound and/or of complexing agent,
the
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colouring effect of these pigment preparations on dry and smooth skin is
minimal or
completely absent. The pigment preparations can be held and kneaded in the
hand.
Even under pressure they exhibit no colouring effect on the dry internal
surfaces of the
hand. The extremely strong adhesion forces can also be demonstrated by another
phenomenon: a pigment preparation torn into small pieces coalescences again
after a
short time to give a completely homogeneous composition. Furthermore, these
pigment
preparations exhibit outstanding reliquefaction when stirred into water. When
stirred
incorporation is performed in the proper art manner, they dissolve completely
within a
short time, usually within just 60 s.
In one preferred embodiment the pigment preparation of the invention is
gellike and
hence retains its shape, so that if the container is damaged there is no leak
of product
and hence no contamination of the environment or of employees.
The pasty or gellike pigment preparations of the invention can be dispensed
readily into
large and small containers. The small containers include, for example, tubes,
syringes,
cartridges, flexible pouches, sealable bags and all other packaging forms
known to the
skilled person for pasty or gellike products, such as dispensers or the like,
for example.
Alternatively they can be dispensed into large containers, such as drums,
sacks or even
bulk bags.
The subject matter of the present invention is apparent not only from the
subject
matter of the individual claims but also from the combination of the
individual
claims with one another. The same applies to all of the parameters disclosed
in the
description and to their combinations of whatever form.
The examples which follow illustrate the invention, without any intention that
they
should restrict it.
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I. Description of the Measuring and Testing Methods used
1.1 Building material colour test
The dispersibility in building materials was tested in cement mortar via the
visual
assessment of blocks produced using white cement, with the following data:
Cement-quartz sand ratio 1:4, water-cement value 0.35, level of pigmentation
2.4%
based on cement, mixer used from RK Toni Technik, Berlin, with 5 1 mixing pan,
model 1551, rotational speed 140 rpm, batch: 1200 g of quartz sand 0.1 to 1
mm, 600 g
of quartz sand I to 2 mm, 200 g of finely ground limestone (< 5% residue on 90
m
sieve), 500 g of white cement. The quartz sand fractions and the finely ground
limestone are charged together to the mixing vessel. They are then premixed
for 10 s
(mixer setting 1: slow). The pigment preparation in solution in water, in the
form of a
suspension, or, in the case of the comparative examples, the water-suspended
pigment
or the water-suspended filtercake, is then added to the initial mixture,
ensuring that the
total amount of water is 175 g and that the water/pigment suspension is
introduced in
the middle of the mixture. When the liquid has seeped in, the cement is added
and the
batch is mixed (mixer setting 1: slow). After a mixing time of 100 s, three
600 g
sainples are taken and used to produce three specimens (10 x 10 x 2.5 cm)
under
pressure (pressing force: 114 kN for 2 seconds). The specimens are cured to
give the
completed blocks: for 24 hours at 30 C and 95% relative humidity, with
subsequent
drying at 60 C for 4 hours. The resulting blocks were inspected.
1.2 Determination of dispersibility in emulsion paints
The dispersibility of chromatic pigments and black pigments in emulsion paints
is
determined using a dissolver. The test medium employed is an emulsion paint
based on
a PVA dispersion (vinyl acetate/Versatic acid vinyl ester) having a pigment
volume
concentration of 55% (pigment/filler ratio 40/60). For the incorporation of
the pigment,
180 g of white emulsion paint are introduced initially, and then 6.0 g of the
chromatic
or black pigment under test - or an amount, converted according to its pigment
content,
of the pasty or gellike pigment preparation, so that in these cases as well
there are 6.0 g
of pigment - are added with stirring (titanium dioxide pigment/chromatic
pigment
weight ratio or titanium dioxide pigment/black pigment weight ratio = 5:1, the
titanium
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dioxide pigment used may be, for example, Tronox R-KB-2, a commercial product
of
Tronox Inc.). A dissolver disc (diameter 4 cm) is used to set the following
dispersing
conditions:
min 1000 rpm (2.1 m/s) and then
5 20 min 2000 rpm (4.2 m/s) and then
10 min 4500 rpm (9.4 m/s)
After the individual dispersing times, a small amount of each paint is removed
and used
to prepare a drawdown with a wet film thickness of 90 m (slot height of the
drawing
bar), which is dried at room temperature. After drying, the drawdowns (coating
films)
10 are scraped using a sharp-edged object, allowing the undispersed pigment
particles of
the chromatic or black pigments to appear at the surface as dots or stripes
(bits). The
dispersing energy for application to the pigments is assessed by the number of
bits
present on the individual scrapes, using a scale of evaluation from level 1 to
level 5:
Level 1: no bits
Level 2: a few bits
Leve13: moderate bits
Level 4: numerous bits
Leve15: a very large number of bits
Dispersibility is good only in the case of evaluation levels 1 and 2; at
levels 3 and
above, the evaluation is insufficient for the dispersing energy employed. The
earlier
the stage at which evaluation levels 1 or 2 are achieved, in other words the
lower the
dispersing energy employed, the better the dispersibility of the pigment or
pigment
preparation under investigation.
1.3 Testing of the colouring effect on dry and smooth surfaces
The colouring effect on dry and smooth surfaces is tested with the aid of a
bolt made
from bright-drawn V4A round steel (material 1.4571). The bolt possesses a
diameter
of 8 mm and is 200 mm long. One end is machined to a point over a length of 10
mm,
as shown in Figure 1. Immediately after it has been prepared, the pigment
preparation is
dispensed into a suitable container which can be given an airtight seal and
which in
terms of its volume is not substantially larger than the pigment preparation.
Such a
container may be, for example, an airtightly sealable polyethylene bottle
having a
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sufficiently large aperture, or an airtightly sealable plastic bucket. When
filling the
container it should be ensured that the fill level within the container is 50
mm. Only
when the pigment preparation has cooled to room temperature (20 to 22 C) is
the
container in question sealed airtightly and stored at room temperature. After
a 24-
hour storage period the colouring effect of the pasty or gellike pigment
preparation
on dry and smooth surfaces is tested. This is done by pressing the clean, dry
bolt,
with the tip foremost, quickly (suddenly) into the pasty or gellike pigment
preparation until the bolt strikes the base of the container. It is then
immediately
withdrawn again quickly (suddenly) from the pasty or gellike pigment
preparation.
Differential weighing before and after immersion is used to determine the mass
of
pasty or gellike pigment preparation adhering to the bolt. The bolt is cleaned
and the
process is carried out a total of three times, the bolt being immersed into
the pasty or
gellike pigment preparation at a different location each time. The average
increase in
mass of the bolt is then calculated from the three weighings. If the average
increase
in mass of the bolt is not more than 0.07 g, preferably not more than 0.04 g,
the
pigment preparation exhibits no colouring effect on dry and smooth surfaces in
the
sense of this invention. In order to demonstrate that an average increase in
mass of
not more than 0.07 g, preferably of not more than 0.04 g, is very small,
comparison
will be made with a liquid paint. Bayferrox 350 liquid (commercial product of
Lanxess Deutschland GmbH) is an aqueous suspension of a black iron oxide
pigment
intended for colouring building materials and having a pigment content of 50%
to 55%.
The sample of Bayferrox 350 liquid investigated for the comparison had a
pigment
content of 53.9% and a viscosity of 1260 mPas (Brookfield viscosity, measured
at
20 C with a No. 4 spindle at 100 rpm). When the test of the colouring effect
on dry and
smooth surfaces is carried out on such a suspension by the process described,
using the
bolt, the average increase in mass of the bolt as a result of the pigment
suspension
adhering to it is 0.73 g.
1.4 Testing for phase separation
Immediately after it has been prepared, the pigment preparation is dispensed
into a
suitable container which can be given an airtight seal and which in terms of
its volume
is not substantially larger than the pigment preparation. A container of this
kind may
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be, for example, an airtightly sealable polyethylene bottle having a
sufficiently large
aperture or an airtightly sealable plastic bucket. Only after the pigment
preparation has
cooled to room temperature (20 to 22 C) is the container in question given an
airtight
seal and stored at room temperature. After a time of at least two months,
preferably at
least six months, a check is made as to whether separation of the phases has
occurred,
in other words as to whether a supernatant liquid phase has formed on the
pigment
preparation. Within the container, particularly in the case of wrongly chosen
dimensions, there may be a little liquid condensed on the wall or on the lid.
Liquid
condensation of this kind should not be taken into account.
1.5 Determination of dispersibility in water
87.5 g of water are introduced into a 150 ml glass beaker (wide shape). The
pasty or
gellike pigment preparation is introduced in one piece into the water with
stirring using
a turbine stirrer (diameter 28 mm) at a speed of 600 rpm. The amount of pasty
or
gellike pigment preparation added is always chosen such that it contains 6 g
of
pigment. After a defined period of time the stirrer is shut off, the pigment
suspension is
tipped through a sieve with a mesh size of 250 m and the sieve is briefly
cleaned with
a shower jet. When there are no longer any residues of the pigment preparation
on the
sieve, in other words when all of the particles of the pigment preparation are
smaller
than 250 m, the pasty or gellike pigment preparation is regarded as being
fully
dissolved.
U. Example 1
735 g of chromium oxide green GN (commercial product of Lanxess Deutschland
GmbH) and 735 g of water were used, with addition of 1.52 g of an aqueous
solution
of sodium polyacrylate with a 40% active compound content, as a wetting and
dispersing additive, to produce a dispersion with a pigment content of 50%.
Then
three drops of Preventol D6 (commercial product of Lanxess Deutschland GmbH)
as a preservative and 38.7 g of pigskin gelatine (240 to 270 g bloom) as a
thickener
were added, and the dispersion was stirred at 45 C for 30 minutes. While still
hot,
the dispersion was tipped into a variety of containers, including children's
baking
trays, and was cooled to room temperature and given an airtight seal. After
around
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two hours noticeable formation of gel had already occurred. After 24 hours it
was
possible to invert the baking trays. The pigment preparation obtained had a
gellike
consistency. The dimensional stability is demonstrated by Figure 2.
The gellike pigment preparation produced did not exhibit a colouring effect on
dry
and smooth surfaces in accordance with the testing method described, since the
average increase in mass of the bolt was 0.006 g. Moreover, it did not show
any
phase separation over a period of several months.
The gellike pigment preparation produced was reliquefiable simply by gentle
heating
to 35 C, with the gel reforming on renewed cooling.
Testing in building materials: 24 g of the gellike pigment preparation were
reliquefied with heating and dissolved in 163 g of heated water. When cooled
to
room temperature, the resulting suspension no longer formed a gel, and was
used for
the building material colour test described. This resulted in blocks with a
homogeneous green colouration.
M. Example 2 (Comparative example to Example 1)
Testing in building materials: For comparison, 12 g of the chromium oxide
green GN
powder used for producing the gellike pigment preparation from Example 1 were
also dispersed in 175 g of water, with stirring, and used for the building
material
colour test described. Again, blocks with a homogeneous green colouration were
obtained. There was no apparent difference from the blocks coloured using the
gellike pigment preparation from Example 1.
IV. Example 3
550 g of Bayferrox 330 (black iron oxide pigment, commercial product of
Lanxess
Deutschland GmbH) were dispersed in 450 g of water. Added to this dispersion
were
6.8 g of kappa-carrageenan as a thickener and three drops of Preventol D6 as
a
preservative, and the dispersion was stirred at 40 C for 30 minutes. While
still hot,
the dispersion was tipped into a variety of containers, including childreri's
baking
trays, and was cooled to room temperature and given an airtight seal. After
around
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one hour noticeable formation of gel had already occurred. After 24 hours it
was
possible to invert the baking trays. The pigment preparation obtained had a
gellike
consistency. The dimensional stability is demonstrated by Figure 3.
The gellike pigment preparation produced did not exhibit a colouring effect on
dry
and smooth surfaces in accordance with the testing method described, since the
average increase in mass of the bolt was 0.004 g. Moreover, it did not show
any
phase separation over a period of several months.
The gellike pigment preparation produced was reliquefiable by heating to 55 C,
with
the gel reforming on renewed cooling.
Testing in building materials: 24 g of the gellike pigment preparation were
reliquefied with heating and dissolved in 163 g of heated water. When cooled
to
room temperature, the resulting suspension no longer formed a gel, and was
used for
the building material colour test described. This resulted in blocks with a
homogeneous black colouration.
V. Example 4 (Comparative example to Example 3)
Testing in building materials: For comparison, 12 g of the Bayferrox 330
powder
used for producing the gellike pigment preparation from Example 3 were also
dispersed in 175 g of water, with stirring, and used for the building material
colour
test described. Again, blocks with a homogeneous black colouration were
obtained.
There was no apparent difference from the blocks coloured using the gellike
pigment
preparation from Example 3.
VI. Example 5
550 g of Bayferrox 330 were dispersed in 450 g of water. Added to this
dispersion
were 6.8 g of a 1:1 mixture of kappa-carrageenan and iota-carrageenan as
thickeners
and three drops of Preventol D6 as a preservative, and the dispersion was
stirred at
40 C for 30 minutes. While still hot, the dispersion was tipped into a variety
of
containers, including the little bear baking tray from Examples I and 3 and
was
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cooled to room temperature and given an airtight seal. After around two hours
noticeable formation of gel had already occurred. After 24 hours it was
possible to
invert the baking trays. The pigment preparation obtained had a gellike
consistency
and was dimensionally stable.
The gellike pigment preparation prepared was softer than that from Example 3.
It did
not exhibit a colouring effect on dry and smooth surfaces in accordance with
the
testing method described, since the average increase in mass of the bolt was
0.013 g.
Moreover, it did not shown any phase separation over a period of several
months.
The gellike pigment preparation produced was reliquefiable by heating to 45 C,
with
the gel refonning on renewed cooling.
VII. Example 6
750 g of chromium oxide green GN were dispersed in a mixture of 500 g of water
and 150 g of a 15% strength Mowiol 18-88 solution as a thickener (Mowiols are
polyvinyl alcohols and are commercial products of Kuraray Specialities Europe
GmbH). The dispersion was transferred to an IKA HKD 2.5 horizontal compounder
with DUPLEX blades, and, while it was being kneaded, over a period of
approximately 5 minutes, 40 g were added of a room-temperature-saturated
potassium tetraborate pentahydrate solution, as a compound which in
combination
with a thickener together raises the firmness. Then kneading and
homogenization
were continued for 30 minutes more. This gave a pigment preparation of pasty
consistency.
The pasty pigment preparation produced did not exhibit any colouring effect on
dry
and smooth surfaces in accordance with the testing method described, since the
average increase in mass of the bolt was 0.00 g. Moreover, it did not exhibit
phase
separation over a period of several months. When the dispersibility in water
was
determined in accordance with the process described, it dissolved completely
within
60 s.
Testing in building materials: 24 g of the pasty pigment preparation were
dissolved
with stirring in 163 g of water and the resulting suspension was used for the
building
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material colour test described. The result was blocks with a homogeneous green
colouration.
Testing in emulsion paint: 12 g of the pasty pigment preparation produced were
used
for the above-described determination of dispersibility in emulsion paints.
The result
was as follows:
min at 1000 rpm evaluation level: 1
min at 2000 rpm evaluation level: 1
10 min at 4500 rpm evaluation level: 1
Evaluation level 1 was reached after 10 min at 1000 rpm. Even at the lowest
dispersing
10 energy, therefore, the pasty pigment preparation exhibited very good
dispersibility.
VIII. Example 7 (Comparative example to Example 6)
Testing in building materials: For comparison, 12 g of the chromium oxide
green GN
powder used for producing the pasty pigment preparation from Example 6 were
dispersed in 175 g of water, with stirring, and used for the building material
colour
15 test described. Again, blocks with a homogeneous green colouration were
obtained.
There was no apparent difference from the blocks coloured using the pasty
pigment
preparation from Example 6.
Testing in emulsion paint: For comparison, 6 g of the chromium oxide green GN
powder used for producing the pasty pigment preparation from Example 6 were
used
20 for the above-described determination of dispersibility in emulsion paints.
The result
was as follows:
10 min at 1000 rpm evaluation level: 5
20 min at 2000 rpm evaluation level: 4
10 min at 4500 rpm evaluation level: 2
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For the chromium oxide green GN powder used it was necessary to select very
intense dispersing conditions in order to achieve effective dispersing
(evaluation
level 2). The chromium oxide green GN powder used, therefore, was much more
difficult to disperse than the pasty pigment preparation from Example 6.
IX. Example 8
The pasty pigment preparation from Example 6 was frozen in an airtightly
sealable
container at -11 C for 60 hours. It was then thawed again to room
temperature. The
rethawed pasty pigment preparation showed no differences from the original
pigment
preparation. No water had separated out. In the determination of the
dispersibility in
water in accordance with the process described it still dissolved completely
within
60 s.
Testing in building materials: 24 g of the rethawed pasty pigment preparation
was
dissolved with stirring in 163 g of water and the resulting suspension was
used for the
above-described building material colour test. The result again was blocks
with a
homogeneous green colouration. No difference could be found from the blocks
from
Example 6 and Example 7.
Accordingly the pasty pigment preparation produced had not suffered impairment
as a
result of the freezing and thawing.
X. Example 9
1000 g of Bayferrox 130M (red iron oxide pigment, commercial product of
Lanxess
Deutschland GmbH) were dispersed in an mixture of 516 g of water, 67 g of a
15%
strength Mowiol 18-88 solution and 83 g of an 8% strength Mowiol 40-88
solution, in each case as thickeners. The dispersion was transferred to an IKA
HKD 2.5 horizontal compounder with DUPLEX blades, and, while it was being
kneaded, over a period of approximately 5 minutes, 30 g were added of a room-
temperature-saturated potassium tetraborate pentahydrate solution, as a
compound
which in combination with a thickener together raises the firmness. Then
kneading
and homogenization were continued for 30 minutes more. This gave a pigment
preparation of pasty consistency.
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The pasty pigment preparation produced did not exhibit any colouring effect on
dry
and smooth surfaces in accordance with the testing method described, since the
average increase in mass of the bolt was 0.00 g. Moreover, it did not exhibit
phase
separation over a period of several months. When the dispersibility in water
was
determined in accordance with the process described, it dissolved completely
within
60 s.
Testing in emulsion paint: 10 g of the pasty pigment preparation produced were
used
for the above-described determination of dispersibility in emulsion paints.
The result
was as follows:
10 min at 1000 rpm evaluation level: 1
min at 2000 rpm evaluation level: 1
10 min at 4500 rpm evaluation level: 1
Evaluation level 1 was reached after 10 min at 1000 rpm. Even at the lowest
dispersing
energy, therefore, the pasty pigment preparation exhibited very good
dispersibility.
15 XI. Example 10
The pasty pigment preparation from Example 9 was frozen in an airtightly
sealable
container at -11 C for 60 hours. It was then thawed again to room
temperature. The
rethawed pasty pigment preparation showed no differences from the original
pigment
preparation. No water had separated out. In the determination of the
dispersibility in
20 water in accordance with the process described it still dissolved
completely within
60 s.
Testing in emulsion paint: 10 g of the pasty pigment preparation rethawed were
used
for the above-described determination of dispersibility in emulsion paints.
The result
was as follows:
10 min at 1000 rpm evaluation level: 1
20 min at 2000 rpm evaluation level: 1
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min at 4500 rpm evaluation level: 1
Evaluation level 1 was reached after 10 min at 1000 rpm. Even at the lowest
dispersing
energy, therefore, the pasty pigment preparation exhibited outstanding
dispersibility.
The dispersibility in emulsion paint had not been impaired as a result of the
freezing
5 and thawing.
XII. Example 11 (Comparative example to Examples 9 and 10)
Testing in emulsion paint: For comparison, 6 g of the Bayferrox 130M powder
used
for producing the pasty pigment preparation from Example 10 were used for the
above-described determination of dispersibility in emulsion paints. The result
was as
10 follows:
10 min at 1000 rpm evaluation level: 5
min at 2000 rpm evaluation level: 5
10 min at 4500 rpm evaluation level: 4
The Bayferrox 130M powder used did not have adequate dispersing properties,
15 since it was not possible to reach evaluation levels 1 or 2. The Bayferrox
130M
powder used, therefore, was much more difficult to disperse than the pasty
pigment
preparations from Examples 9 and 10 that were produced from it.
XIII. Example 12
A yellow iron oxide pigment produced by the precipitation method was filtered
after
20 synthesis and washed free of salt. The resulting filtercake had a solids
content of
51.4%. In a mixture of 242 g of water, 155 g of a 15% strength Mowiol 18-88
solution
and 58 g of an 8% strength Mowiol 40-88 solution, first of all 1.39 g of
Walocel
CRT 40000GA (sodium carboxyrnethylcellulose, commercial product of Wolff
Cellulosics GmbH & Co. KG), as an additional thickener, were dissolved.
Dispersed in
this solution were 973 g of the filtercake, giving a dispersion with a pigment
content of
35%. The pigment suspension was transferred to an IKA HKD 2,5 horizontal
compounder with DUPLEX blades, and, in the course of kneading, over a period
of
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approximately 5 minutes, 40 g were added of a room-temperature-saturated
potassium
tetraborate pentahydrate solution with an active substance content of
approximately
40%, as compound which in combination with a thickener together raises the
firmness.
Then kneading and homogenization were continued for 30 minutes more. This gave
a
pigment preparation of pasty consistency.
The pasty pigment suspension produced did not exhibit any colouring effect on
dry and
smooth surfaces in accordance with the test method described, since the
average
increase in mass of the bulk was 0.00 g. Moreover, it showed no phase
separation over
a period of several months. When the dispersibility in water was determined in
accordance with the method described, it dissolved completely within 100 s.
Testing in buildiniz materials: 34.3 g of the pasty pigment preparation were
dissolved
with stirring in 152 g of water and the resulting suspension was used for the
building
material colour test described. The result was blocks with a homogeneous
yellow
colouration.
Testing in emulsion paint: 17.1 g of the pasty pigment preparation produced
were
used for the above-described determination of dispersibility in emulsion
paints. The
result was as follows:
10 min at 1000 rpm evaluation level: 1
min at 2000 rpm evaluation level: 1
20 10 min at 4500 rpm evaluation level: 1
Evaluation level 1 was reached after 10 min at 1000 rpm. Even at the lowest
dispersing
energy, therefore, the pasty pigment preparation exhibited very good
dispersibility.
XIV. Example 13 (Comparative example to Example 12)
Testing in building materials: For comparison, 23.3 g of the filtercake used
for
producing the pasty pigment preparation from Example 12 were dissolved in
163.7 g
of water, with stirring, and the resulting suspension was used for the
building
material colour test described. Again, blocks with a homogeneous yellow
colouration
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were obtained. These blocks, however, were substantially less brilliant in
comparison
to those from Example 12, owing to the much lower yellow tint.
Testing in emulsion paint: For comparison, 11.7 g of the filtercake used for
producing the pasty pigment preparation from Example 12 were used for the
above-
described determination of dispersibility in emulsion paints. The result was
as
follows:
min at 1000 rpm evaluation level: 5
min at 2000 rpm evaluation level: 5
10 min at 4500 rpm evaluation level: 4
10 The filtercake used was not sufficiently dispersible, since it was not
possible to
achieve evaluation levels 1 or 2. Under all dispersing conditions the
dispersing
energy employed was insufficient. The filtercake used, therefore, was much
more
difficult to disperse than the pasty pigment preparation from Example 12
produced
from it.
15 XV. Example 14
A black iron oxide pigment produced by the precipitation method was filtered
after
synthesis, washed free of salt and dried using a disc spray drier. Then, in a
mixture of
22.3 kg of water and 8.55 kg of an 8% strength Mowiol 40-88 solution, 39.5 g
of
Walocel CRT 40000GA, in each case as a thickener, were dissolved. Stirred into
this
20 solution were 33.75 kg of the dry black pigment powder, which was dispersed
using a
bead mill with 1 mm grinding beads of zirconium oxide, giving a dispersion
with a
pigment content of 52%. 1.44 kg of this dispersion were transferred to an IKA
HKD 2,5 horizontal compounder with DUPLEX blades, and, in the course of
kneading,
over a period of approximately 5 minutes, 30 g were added of a room-
temperature-
saturated potassium tetraborate pentahydrate solution, as compound which in
combination with a thickener together raises the firnuiess. Then kneading and
homogenization were continued for 30 minutes more. This gave a pigment
preparation
of pasty consistency.
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The pasty pigment preparation produced did not exhibit any colouring effect on
dry and
smooth surfaces in accordance with the test method described, since the
average
increase in mass of the bulk was 0.00 g. Moreover, it showed no phase
separation over
a period of several months. When the dispersibility in water was determined in
accordance with the method described, it dissolved completely within 60 s.
Testing in building materials: 23 g of the pasty pigment preparation were
dissolved
with stirring in 164 g of water and the resulting suspension was used for the
building
material colour test described. The result was blocks with a homogeneous black
colouration.
Testing in emulsion paint: 11.5 g of the pasty pigment preparation produced
were
used for the above-described determination of dispersibility in emulsion
paints. The
result was as follows:
10 min at 1000 rpm evaluation level: 1
min at 2000 rpm evaluation level: 1
15 10 min at 4500 rpm evaluation level: 1
Evaluation level 1 was reached after 10 min at 1000 rpm. Even at the lowest
dispersing
energy, therefore, the pasty pigment preparation exhibited very good
dispersibility.
XVI. Example 15
The pasty pigment preparation from Example 14 was frozen in an airtightly
sealable
20 container at -11 C for 60 hours. It was then thawed again to room
temperature. The
thawed pasty pigment preparation showed no differences from the original
pigment
preparation. No water had separated out. In the determination of the
dispersibility in
water in accordance with the process described it still dissolved completely
within
60 s.
Testing in building materials: 23 g of the rethawed pasty pigment preparation
were
dissolved with stirring in 164 g of water and the suspension obtained was used
for the
above-described building material colour test. The result, again, was blocks
with a
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homogeneous black coloration. There was no apparent difference from the blocks
from Example 14.
Testing in emulsion paint: 11.5 g of the pasty pigment preparation thawed were
used
for the above-described determination of dispersibility in emulsion paints.
The result
was as follows:
min at 1000 rpm evaluation level: 1 to 2
min at 2000 rpm evaluation level: 1
10 min at 4500 rpm evaluation level: 1
Evaluation level 1 to 2 was reached after 10 min at 1000 rpm. Even at the
lowest
10 dispersing energy, therefore, the pasty pigment preparation exhibited
outstanding
dispersibility.
The pasty pigment preparation produced, therefore, had not been impaired as a
result of
the freezing and thawing.
XVII. Example 16 (Comparative example to Examples 14 and 15)
15 Testing in building materials: For comparison, 12 g of the dry black
pigment powder
used to produce the pasty pigment preparation from Example 14 were dispersed
with
stirring in 175 g of water and the resulting suspension was used for the above-
described building material colour test. Again, blocks with a homogeneous
black
coloration were obtained. There was no apparent difference from the blocks
coloured
20 using the gellike pigment preparations from Examples 14 and 15.
Testing in emulsion paint: For comparison, 6 g of the dry black pigment powder
used
for producing the pasty pigment preparation from Example 14 were used for the
above-described determination of dispersibility in emulsion paints. The result
was as
follows:
10 min at 1000 rpm evaluation level: 5
20 min at 2000 rpm evaluation level: 4 to 5
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min at 4500 rpm evaluation level: 2
With the dried black pigment powder used it was necessary to select very
intense
dispersing conditions in order to achieve effective dispersing (evaluation
level 2).
The dried black pigment powder used, therefore, was much more difficult to
disperse
5 than the pasty pigment preparations from Examples 14 and 15.
XVIII. Example 17
33 g of Mowiol 8-88, as a thickener, were dissolved in 656 g of water with
gentle
warming. Then, with dispersion, 800 g of Tronox A-Z (titanium dioxide pigment,
commercial product of Tronox Inc.) were added. The dispersion was transferred
to an
10 IKA HKD 2,5 horizontal compounder with DUPLEX blades, and 25 g of solid
sodium tetraborate pentahydrate, as a compound which in combination with a
thickener
together raises the firmness, were added in portions. Then kneading and
homogenization were continued for 10 minutes more. This gave a pigment
preparation
of pasty consistency.
The pasty pigment preparation produced exhibited no colouring effect on dry
and
smooth surfaces in accordance with the test method described, since the
average
increase in mass of the bolt was 0.0 12 g. Moreover, it did not show any phase
separation over a period of several months.
XIX. Example 18
6.8 g of carubine, as a thickener, were dissolved in 675 g of water with
heating to
more than 80 C. The carubine solution was transferred to an IKA HKD 2,5
horizontal compounder with DUPLEX blades, and 1 ml of Preventol D6, as a
preservative, was added. Then, in portions 6.8 g of Kelzan (xanthane,
commercial
product of CP Kelco Germany GmbH) were added, as a further thickener, until a
homogeneous composition formed. Gradually, in portions, 825 g of Bayferrox 130
(red iron oxide pigment, commercial product of Lanxess Deutschland GmbH) were
added to this composition and incorporated with kneading. Then kneading and
homogenization were continued for 30 minutes more. This gave a pigment
preparation with a pasty, rubbery consistency. For further homogenization, the
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pigment preparation was heated at 85 to 90 C for a short time in a sealed
container.
The pigment preparation underwent liquefaction; as it cooled, a pigment
preparation
of pasty, rubbery consistency was formed again. As a result of its production
and
homogenization at relatively high temperatures, some of the water had
evaporated,
and the pasty, rubbery pigment preparation obtained had a pigment content of
58.6%
by weight.
The pasty, rubbery pigment preparation produced did not exhibit any colouring
effect
on dry and smooth surfaces in accordance with the test method described, since
the
average increase in mass of the bolt was 0.02 g. Moreover, it did not exhibit
any phase
separation over a period of several months.
Testing in building materials: 20.4 g of the pasty, rubbery pigment
preparation were
admixed with 10% by weight of sodium periodate and left to stand for 24 hours.
In the
course of this time the pasty, rubbery pigment preparation underwent
reliquefaction.
The liquefied pasty pigment preparation was suspended with stirring in 166.6 g
of
water, and the suspension obtained was used for the above-described building
material
colour test. This gave blocks with a homogeneous red coloration.
XX. Example 19 (Comparative example to Example 19)
Testing in building materials: For comparison, 12 g of the Bayferrox 130
powder used
for producing the gellike pigment preparation from Example 18 were also
dispersed in
175 g of water, with stirring, and used for the building material colour test
described.
Again, blocks with a homogeneous red coloration were obtained. There was no
apparent difference from the blocks coloured using the gellike pigment
preparation
from Example 18.
XXI. Example 20
XXII. 3.75 g of carubine, as a thickener, were dissolved in 750 g of water
with
heating to more than 80 C. The carubine solution was transferred to an IKA
HKD 2,5 horizontal compounder with DUPLEX blades, and 1 ml of
Preventol D6, as a preservative, was added. Then, in portions 7.5 g of
Kelzan were added, as a further thickener, until a homogeneous composition
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formed. Gradually, in portions, 750 g of Bayferrox 130 (red iron oxide
pigment, commercial product of Lanxess Deutschland GmbH) were added to
this composition and incorporated with kneading. Finally, in addition, 45 g of
Aerosil 200 (hydrophilic fumed silica, commercial product of Degussa
GmbH) were added as a filler. Then kneading and homogenization were
continued for 30 minutes more. This gave a pigment preparation with a pasty,
rubbery consistency.
For further homogenization, the pigment preparation was heated at 85 to 90 C
for a
short time in a sealed container. After cooling, a pigment preparation of
pasty,
rubbery consistency formed again within a few days.
The pasty, rubbery pigment preparation produced did not exhibit any colouring
effect
on dry and smooth surfaces in accordance with the test method described, since
the
average increase in mass of the bolt was 0.01 g. Moreover, it did not exhibit
any
phase separation over a period of several months.
III. The figures
The bolt for testing the colouring effect on dry and smooth surfaces, and also
the
dimensional stability of the pigment preparation, are illustrated by reference
to a
number of figures. In this case the figures indicate further inventively
essential features
and advantages of the invention. In these figures:
Figure 1 shows a bolt of bright-drawn V4A round steel (material 1.4571) with a
diameter of 8 mm and a length of 200 mm. One end of the bolt is
machined to a point over a length of 10 mm. The bolt is used for testing
the colouring effect on dry and smooth surfaces.
Figure 2: Gellike pigment preparation from Example 1. The photos are intended
to demonstrate the dimensional stability. A one euro coin is used for
size comparison.
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Figure 3: Gellike pigment preparation from Example 3. The photos are intended
to demonstrate the dimensional stability. A one euro coin is used for
size comparison.
