Note: Descriptions are shown in the official language in which they were submitted.
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WO 2010/018044 PCT/EP2009/059136
Dispersing agent and its use
The invention relates to block copolymers, more
particularly those suitable for use as dispersants,
especially in paints and varnishes.
In the production of paints, varnishes, printing inks,
and other coating materials, dispersants facilitate the
incorporation of solids, such as fillers and pigments,
for example, which, as important formulating
ingredients, substantially determine the visual
appearance and the physicochemical properties of
systems of this kind. For optimum utilization, these
solids must be dispersed uniformly in the formulations,
and the dispersion, once achieved, must be stabilized.
A multiplicity of different substances are nowadays
used as dispersants for solids. In addition to very
simple compounds of low molecular weight, such as
lecithin, fatty acids and their salts, and alkylphenol
ethoxylates, for example, polymers, too are used as
dispersants.
The use of such products, however, is also frequently
associated with a multiplicity of disadvantages: On use
in pigment pastes, high levels of dispersing additives
are often necessary; the levels of paste pigmentation
that can be achieved are unsatisfactorily low; the
stability of the pastes and hence the consistency of
their viscosity is inadequate; and flocculation and
aggregation are not always avoidable. In many cases,
there is a lack of shade consistency following storage
of the pastes, and a lack of compatibility with diverse
binders.
The use of known dispersing additives in many cases
also adversely affects the water resistance or light
stability of coating materials, and, in addition, the
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unwanted foam that is formed in the course of
preparation and processing is stabilized.
There is therefore a growing need for dispersants for
solids that exhibit further-improved properties
relative to the prior art. The requirement, for
example, is for dispersants which achieve a maximum
stabilizing action on a multiplicity of different
solids and/or achieve improved depth of shade of the
pigments in the coating material.
WO 01/44389 describes pigment dispersions with as
dispersant a polymer compound which is obtainable by
controlled radical polymerization and has the formula
X-(G)p-(E)S-T, where G is a moiety of a radically
polymerizable ethylenically unsaturated monomer, E is a
hydrophilic moiety of a radically polymerizable
ethylenically unsaturated monomer, E and G being
different, X is a hydrophobic radical originating from
the initiator used, and T is a radical transfer group
originating from the initiator used, and p and s are
selected such that the average molecular weight is at
least 250 g/mol.
US 7,199,177 describes a pigment composition containing
from 0.1% to 99.9% by weight of a block copolymer of
the formula X- [Gp-ES]b-Tc, where G is a polymer block of
repeating units of (meth)acrylic acid C1-C24 alkyl
esters, E is a polymer block of repeating units of
(meth)acrylic acid C1-C24 alkyl esters which are
copolymerized with at least 50% by weight of monomers
which carry functional groups, X is a radical
originating from the initiator used, T is a polymer
chain end group, and c, p, and s are each > 0.
WO 00/40630 describes compositions comprising as
dispersants compounds of the formula X,- [AX-By] -Tc, where
X is an initiator fragment, A and B are polymer blocks
with different polarities, and x and y indicate the
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number of monomer units in each of the blocks, and T
represents a chain polymer termination group. The
dispersants described in WO 00/40630 are obtained by
atom transfer radical polymerization (ATRP).
Atom transfer radical polymerization (ATRP) represents
a versatile process for preparing a multiplicity of
polymers and copolymers such as, for example,
polyacrylates, polymethacrylates, polystyrenes or
copolymers. The ATRP method was developed in the 1990s
by Prof. Matyjaszewski, and is described in references
including J. Am. Chem. Soc., 1995, 117, p. 5614 and
WO 97/18247. A particular advantage of ATRP is that not
only the molecular weight but also the molecular weight
distribution can be regulated. As a living
polymerization, furthermore, it allows the controlled
construction of polymer architectures such as, for
example, random copolymers or else block copolymer
structures. Through corresponding initiators, for
example, unusual block copolymers and star polymers are
additionally obtainable. Theoretical principles of the
polymerization mechanism are elucidated in references
including Hans Georg Elias, Makromolekule, volume 1, 6th
edition, Weinheim 1999, p. 344.
The ATRP process is based on a redox equilibrium
between the growing radical polymer chain, which is
present only at a low concentration, and a transition
metal compound in a higher oxidation state (e.g.,
copper II), and the dormant, preferential combination
of the polymer chain terminated with a halogen or
pseudohalogen, and the corresponding transition metal
compound in lower oxidation state (e.g., copper I).
This is true not only of ATRP in the actual form, which
is initiated with correspondingly (pseudo-)halogen-
substituted initiators, but also of reverse ATRP, in
which the halogen is attached to the polymer chain only
when the equilibrium is established.
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Irrespective of the process selected, after termination
of the reaction, the halogen atom always remains at the
respective chain ends. The presence of this organically
bonded halogen, and particularly of the organically
attached bromine, however, is disadvantageous for the
use of polymers prepared by the ATRP method, since such
compounds can lead to allergies and, furthermore, are
poorly metabolized by the body and tend to accumulate
in the fatty tissue.
The transition metal compounds used in ATRP, and
especially the Cu compounds that are used in the great
majority of the polymer syntheses, are likewise
disadvantageous, since copper, even at low
concentrations, leads to strongly colored products.
Furthermore, copper compounds may be irritant and
sensitizing on contact with the skin.
A simple and efficient method for removing the terminal
halogen atoms and the transition metal compound is
therefore of great interest. Particularly desirable are
methods in which both are achieved in a simultaneous
process step, in order to make the purification of the
polymers as efficient and cost-effective as possible.
One of the patents describing methods for removing
transition metal compounds from polymers or polymer
solutions is DE 10 2006 015 846. DE 10 2006 015 846
describes a method for removing transition metal
compounds from polymer solutions, characterized in that
the transition metal compound is precipitated by
addition of a sulfur-containing precipitant, such as a
mercaptan or a compound having a thio group, for
example, and is removed by filtration. The content of
the cited document is referred to expressly, and the
content of the cited documents is considered part of
the disclosure content of the present specification.
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Methods for removing the terminal halogen atoms are
described in locations including the following:
US 2005/0900632 discloses a process for the
substitution of the halogens by means of metal
alkoxides, with precipitation of the metal halide
formed. Disadvantages of this procedure, however, are
the limited availability of the metal alkoxides, the
costs thereof, and the fact that the process can be
carried out only after purification of the polymers.
WO 00/34345 and Heuts et al. (Macromol. Chem. Phys.,
1999, 200, pp. 1380-1385) describe the implementation
of ATRP with initial addition of sulfur compounds (n-
dodecyl mercaptan and octyl mercaptan, respectively).
In both cases, thermally more stable polymers that are
probably halogen-free are described; in both cases,
however, it is also noted that the width of the
molecular weight distribution is greater than 1.6 and
is therefore very similar to that of a free-radically
polymerized material. The ATRP advantages of products
with narrow distribution and of control over the
polymer architecture are therefore no longer available.
The procedure described, moreover, does not refer to
precipitation of the transition metal compounds.
WO 2005/098415 describes the substitution of the
terminal halogen atoms in polystyrenes, which is, in
turn, polymer-analogous - that is, carried out after
the purification of the polymer. Here, substitution
takes place exclusively only at one chain end, with
thiourea and with subsequent quenching with sodium
hydroxide to form sodium sulfide groups. Disadvantages,
in addition to the two-stage procedure, are the
unilateral substitution, and also the implementation of
the reaction after the polymer has been purified.
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WO 2008/017523 discloses a process for removing halogen
atoms from polymers and separating off transition metal
compounds, characterized in that the halogen atoms are
substituted by addition of a suitable sulfur compound,
as for example a mercaptan or an organic compound
having a thio group, and simultaneously the transition
metal compound is precipitated by this sulfur compound
and subsequently separated off by filtration.
On the basis of the known prior art, an object of the
present invention was to provide alternative
dispersants which preferably permit improved dispersing
of pigments, and also to provide improved processes for
preparing these dispersing additives.
Surprisingly it has been found that this object is
achieved by means of block polymers as claimed in claim
1.
The present invention accordingly provides block
copolymers as claimed in claim 1, a process for
preparing them, compositions which comprise these block
copolymers, especially as dispersants, and the use of
these compositions, as described in the claims.
The block copolymers of the invention have the
advantage that they possess only a low (< 5 ppm by
mass) fraction of terminally bonded bromine and when
used in coating formulations result in improved depth
of shade.
The block copolymers of the invention, a process for
preparing them, and their use are described by way of
example below, without any intention that the invention
should be confined to these exemplary embodiments.
Where ranges, general formulae or classes of compound
are indicated below, they should be taken to include
not only the corresponding ranges or groups of
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compounds that are mentioned explicitly, but also all
subranges and subgroups of compounds that may be
obtained by extraction of individual values (ranges) or
compounds. Where documents are cited in the context of
the present description, the intention is that their
content should belong in its entirety to the disclosure
content of the present invention.
The block copolymers of the invention, of the formula
E-[AB]-T, where E is an initiator fragment of a
polymerization initiator which is capable of initiating
an atom transfer radical polymerization, A and B are
different polymer blocks, and T is a chain polymer
termination group, are distinguished by the fact that
the polymer block A is built from monomers of the
formula Al:
R'
G R3
-::~Iy X
0 (Al)
and the polymer block B is formed by a copolymer of
monomers of the formula B1:
RI
4
~Iy O~DI--,' R
o (B1)
where D is a divalent radical of the general formula
(Cl)
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-(C2H40)i (C3H60)j (C4HeO)k(C12H240)1(CeH8O)
(CI)
where i, j, k, 1, and m are mutually independent
integers from 0-100, with the proviso that the sum of
i + j + k + 1 + m > 1, and, if more than one of the
indices i, j, k, 1, and m is > 0, the general formula
(Cl) represents a random oligomer, a block oligomer or
a gradient oligomer,
and monomers of the formula B2:
R' R6
I
G~Jr N'--1
-;~-'Y Y
0 (B2)
where R1 independently at each occurrence is H or alkyl,
preferably methyl,
G = oxygen or NR2, where R2 independently at each
occurrence is H or alkyl having 1 to 8 C atoms,
preferably G = oxygen. In the case of G = NR2, R2 is
preferably H; R3 is aryl or arylalkyl radical,
preferably phenyl or naphthyl radical, more preferably
phenyl radical, R4 is alkyl, preferably C1 to C3 alkyl,
more preferably methyl, R6 and R7 independently of one
another are alkyl radicals, preferably C1 to C3 alkyl,
more preferably methyl, x = 0 to 10, preferably 1 to 4,
more preferably 1, and y is 1 to 10, preferably 1 to 4,
more preferably 2.
In the formula (Cl) the index i is preferably greater
than 0, more preferably from 10 to 15. With particular
preference the indices i and j are greater than 0.
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The polymer chain termination group T is preferably a
sulfur-containing radical -SQ where Q is a monovalent
organic radical, which is preferably an alkyl radical,
an alcohol radical or an acid radical, more preferably
having 1 to 20 carbon atoms. With particular preference
the group T is a radical obtained by eliminating a
hydrogen atom (the acidic hydrogen) from the compounds
of the group encompassing thioglycolacetic acid,
mercaptopropionic acid, mercaptoethanol,
mercaptopropanol, mercaptobutanol, mercaptohexanol,
octyl thioglycolate, methyl mercaptan, ethyl mercaptan,
butyl mercaptan, dodecyl mercaptan, isooctyl mercaptan,
and tert-dodecyl mercaptan, it being possible for these
compounds to be unsubstituted or substituted;
preferably, however, they are unsubstituted.
In the block copolymer of the invention, the polymer
block A preferably has a number-average molecular
weight of 500 g/mol to 100 000 g/mol. The polymer block
B preferably has a number-average molecular weight of
1000 g/mol to 200 000 g/mol, more preferably a number-
average molecular weight of 5000 g/mol to
100 000 g/mol, and very preferably of 5000 g/mol to
75 000 g/mol. Particularly preferred block copolymers
are those in which both the polymer block A and the
polymer block B have a molecular weight within the
preferred range.
The block copolymer of the invention preferably has a
number-average molecular weight of 1500 g/mol to
500 000 g/mol, more preferably of 5000 g/mol to
100 000 g/mol, and very preferably of 10 000 g/mol to
75 000 g/mol.
The block copolymer of the invention contains
preferably less than 5 ppm by mass, more preferably
less than 2 ppm by mass, of organically bonded, more
particularly of terminal, halogen, more particularly
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bromine. With particular preference the block copolymer
contains no organically bonded halogen or at least only
undetectable amounts of organically bonded halogen.
The block copolymers of the invention can be prepared
in a variety of ways. The block copolymers of the
invention are preferably obtainable by the process
described below.
The process of the invention for preparing the block
copolymers of the invention is distinguished by the
fact that it comprises the steps of
A) reacting an atom transfer radical initiator, of
the formula EX, having at least one organically bonded
halogen atom X, with monomers of the formula Al in the
presence of at least one transition metal-containing
catalyst, in a polymerization step,
B) reacting the compounds obtained in step A) with
the compounds B1 and B2, and
C) adding a compound TH to the polymerization mixture
from step B),
where A, B, B1, B2, and T have the definition described
above.
Use is made as compound TH preferably of
thioglycolacetic acid, mercaptopropionic acid,
mercaptoethanol, mercaptopropanol, mercaptobutanol,
mercaptohexanol, octyl thioglycolate, methyl mercaptan,
ethyl mercaptan, butyl mercaptan, dodecyl mercaptan,
isooctyl mercaptan or tert-dodecyl mercaptan.
As initiator EX it is possible to make use of any
compound which has an atom or a group of atoms which
can be transferred radically under the polymerization
conditions of the ATRP process. Preference is given to
using p-toluenesulfonyl chloride, 2-chloro- or 2-
bromopropionic acid, 2-chloro- or 2-bromoisobutyric
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acid, 1-phenethyl chloride or bromide, methyl or ethyl
2-bromo- or 2-chloropropionate, ethyl or methyl 2-
chloro- or 2-bromoisobutyrate, chloro- or
bromoacetonitrile, 2-chloro- or 2-bromopropionitrile,
(x-bromo-benzacetonitrile or (x-bromo-y-butyro1actone.
As monomers Al, B1, and B2, the monomers stated above
can be used. As monomers of the formula Al it is
preferred to use benzyl acrylate or methacrylate, more
preferably benzyl methacrylate.
As monomers of the formula B1 it is preferred to use
methylpolyethylene glycol methacrylates, preferably
having 10 to 15, more preferably having 11 to 13,
ethylene oxide units. As monomers of the formula B2 it
is preferred to use dimethylaminoalkyl methacrylate,
where alkyl = methyl, ethyl, propyl or butyl,
preferably methyl.
Process steps A) and B) can be carried out as ATRP.
Suitable transition metal-containing catalysts for
process steps A) and B) are, for example, those
transition metal compounds as described in more detail
in, for example, Chem. Rev. 2001, 101, p. 2921 ff.,
expressly incorporated by reference. Generally
speaking, it is possible to use any transition metal
compounds which are able to form a redox cycle with the
initiator, or with the polymer chain containing a
transferable group of atoms - a halogen, for example.
Catalysts used with preference are selected from the
compounds of copper, iron, cobalt, chromium, manganese,
molybdenum, silver, zinc, palladium, rhodium, platinum,
ruthenium, iridium, ytterbium, samarium, rhenium and/or
nickel, more particularly those in which the transition
metal is present in oxidation state I. Copper compounds
are used with preference. As copper compounds it is
preferred to use those selected from Cu20, CuBr, CuCl,
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CuI, CuN3, CuSCN, CuCN, CuN02, CuN03, CuBF4, Cu (CH3000 )
or Cu(CF3COO), and mixtures thereof.
Alternatively to the implementation of process steps A)
and B) as ATRP, they may also be carried out as what is
called reverse ATRP. In this variant of the process,
transition metal compounds in higher oxidation states
can be used, such as CuBr2, CuC12, CuO, CrCl3, Fe203 or
FeBr3, for example. In these cases, the reaction can be
initiated by means of conventional free-radical
initiators such as AIBN, for example. The transition
metal compounds here are initially reduced, since they
are reacted with the radicals generated from the
conventional free-radical initiators. Reverse ATRP has
been described by authors including Wang and
Matyjaszewski in macromolecules, 1995, 28, p. 7572 ff.,
expressly incorporated by reference.
One variant of reverse ATRP represents the additional
use of metals in the oxidation state zero. Through an
assumed comproportionation with the transition metal
compounds at the higher oxidation state, the rate of
reaction is accelerated. This process is described in
more detail in WO 98/40415, expressly incorporated by
reference.
Further variants of ATRP include, for example, the AGET
method (activator generated by electron transfer), the
ICAR method (initiator for continuous activator
regeneration), and the ARGET method (activators
regenerated by electron transfer). A comprehensive
description of these variants is found in T. Pintauer &
K. Matyjaszewski, Chem. Soc. Rev., 2008, 37, pages
1087-1097.
In order to increase the solubility of the metal
compounds in the reaction solution and at the same time
to prevent the formation of stable organometallic
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compounds which as a result are inactive in
polymerization, it may be advantageous to add ligands
to the reaction mixture. Additionally, through the
addition of ligands, it is possible to facilitate the
abstraction of the transferable group of atoms by the
transition metal compound. A listing of suitable
ligands is found in WO 97/18247, WO 97/47661 or
WO 98/40415, for example. The compounds used as ligands
preferably contain usually one or more nitrogen,
oxygen, phosphorus and/or sulfur atoms as a
coordinative constituent. Particular preference is
given in this context to nitrogen-containing compounds.
Especially preferred are nitrogen-containing chelate
ligands. Examples of particularly suitable ligands are,
for example, 2,2'-bipyridine, N,N,N',N",N"-pentamethyl-
diethylenetriamine (PMDETA), tris(2-aminoethyl)amine
(TREN), N,N,N'N'-tetramethylethylenediamine or
1,1,4,7,10,10-hexamethyltriethylenetetramine. For the
skilled person it is obvious that a multiplicity of
further ligands may likewise be used.
These ligands may form coordination compounds with the
metal compounds in situ, or they may first be prepared
as coordination compounds and then added to the
reaction mixture.
The ratio of ligand to transition metal is dependent on
the denticity of the ligand and on the coordination
number of the transition metal. In process step A) the
amount of ligand used is preferably such that the molar
ratio of ligand to transition metal is from 100:1 to
0.1:1, preferably 6:1 to 0.1:1, and more preferably 3:1
to 1:1.
The polymerization in steps A) and B) may take place in
bulk or in solution. The polymerization in steps A) and
B) may be carried out as an emulsion polymerization,
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miniemulsion or microemulsion polymerization or
suspension polymerization.
Where steps A) and B) are carried out in the presence
of a solvent, it is preferred to use halogen-free
solvents, more preferably toluene, xylene, acetates,
preferably butyl acetate, ethyl acetate, propyl
acetate; ketones, preferably ethyl methyl ketone,
acetone; ethers; aliphatics, preferably pentane,
hexane; or alcohols, preferably cyclohexanol, butanol,
hexanol. Water or mixtures of water and water-miscible
solvents may also be suitable solvents.
The polymerization in steps A) and B) may be carried
out under atmospheric pressure, subatmospheric or
superatmospheric pressure, preferably under atmospheric
pressure. The polymerization is carried out preferably
in a temperature range from -20 C to 200 C, more
preferably from 0 C to 130 C, very preferably from 30 C
to 120 C.
The termination of the polymerization in steps A) and
B) may take place, for example, in a way known to the
skilled person, by oxidation of the transition metal.
This can be accomplished, for example, by introducing
oxygen into the polymerization mixture, such as by
passing air through it, for example.
Step C) may see the sulfur compound TH (Q-SH) added to
the polymerization mixture from step B), as for example
after or during the termination of the polymerization
reaction. The compound TH may be added directly or else
a suitable compound may be added from which a compound
TH is obtained or released.
The addition of the sulfur compound TH may be made
directly to the polymerization mixture obtained in
polymerization step B), or else to a worked-up
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polymerization mixture. Preferably the addition is made
directly to the polymerization mixture obtained in
process step B), without prior workup.
The sulfur compound TH is used only in a minimal
excess, based on the chain ends (organically bonded
halogen) of 1.6 equivalents, preferably 1.2
equivalents, and more preferably from 1 to 1.1
equivalents. As a result of the addition of the
mercapto-functionalized sulfur compound, there is
removal of the terminal halogen atoms, presumably by
substitution thereof. Furthermore, in the same step,
the transition metal compound is precipitated in such a
way that it can be removed from the polymer solution in
a simple filtration. This minimal excess also results
in only a very low residual sulfur content of the
polymer solution, one which is readily removable by
modification of the subsequent filtration step, by the
addition, for example, of adsorbents such as activated
carbon to the mixture, or by the use as filter material
of an activated carbon filter.
As a result of the at least equivalent addition of
sulfur compounds TH it is possible to obtain the block
copolymers of the invention, which are halogen-free or
virtually halogen-free. With this step, moreover, it is
possible to ensure that block copolymers with terminal
thioether groups having a copper content < 5 ppm by
mass, more preferably < 2 ppm by mass, can be obtained.
The sulfur compounds TH may contain one or more SH
groups. In the process of the invention it is
preferred, as sulfur compounds Q-SH, to make use of
thioglycolacetic acid, mercaptopropionic acid,
mercaptoethanol, mercaptopropanol, mercaptobutanol,
mercaptohexanol, octyl thioglycolate, methyl mercaptan,
ethyl mercaptan, butyl mercaptan, dodecyl mercaptan,
isooctyl mercaptan or tert-dodecyl mercaptan.
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The skilled worker readily realizes that the sulfur
compounds described, on addition to the polymer
solution after the end of the polymerization, apart
from the described substitution reaction of the
terminal halogen atoms, will have no further influence
on the polymers. This is true in particular in respect
of the molecular weight distributions, the number-
average molecular weight of the units A and B,
additional functionalities, glass transition
temperatures, or melting temperatures in the case of
semicrystalline polymers, and polymer architectures
such as branching systems or block structures.
The block copolymers of the invention may be used more
particularly as dispersants.
Particularly preferred compositions are therefore those
compositions which comprise block copolymers of the
invention as dispersants, preferably as sole
dispersant. In addition to the dispersant, the
composition may comprise water and, possibly, further
ingredients, or may be composed of water and
dispersant, more particularly exclusively block
copolymers of the invention, particularly if it is a
dispersant composition. As further ingredients possibly
present, the composition of the invention may comprise
solids - for example, a pigment or two or more
pigments.
A solid for the purposes of the present invention may
in principle be any solid organic or inorganic
material.
Examples of such solids are pigments, fillers, dyes,
optical brighteners, ceramic materials, magnetic
materials, nanodisperse solids, metals, biocides,
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agrochemicals, and drugs, which are employed as
dispersions.
Preferred solids are pigments as specified, for
example, in the "Colour Index, Third Edition, Volume 3;
The Society of Dyers and Colorists (1982)" and in the
subsequent revised editions.
Examples of pigments are inorganic pigments, such as
carbon blacks, titanium dioxides, zinc oxides, Prussian
blue, iron oxides, cadmium sulfides, chromium pigments,
such as, for example, chromates, molybdates, and mixed
chromates and sulfates of lead, zinc, barium, calcium,
and mixtures thereof. Further examples of inorganic
pigments are given in the book "H. Endriss, Aktuelle
anorganische Bunt-Pigmente, Vincentz Verlag, Hannover
(1997)".
Examples of organic pigments are those from the group
of the azo, diazo, condensed azo, naphthol, metal
complex, thioindigo, indanthrone, isoindanthrone,
anthanthrone, anthraquinone, isodibenzanthrone,
triphendioxazine, quinacridone, perylene,
diketopyrrolopyrrole, and phthalocyanine pigments.
Further examples of organic pigments are stated in the
book "W. Herbst, K. Hunger, Industrial Organic
Pigments, VCH, Weinheim (1993)".
Other preferred solids are fillers, such as, for
example, talc, kaolin, silicas, barites, and lime;
ceramic materials, such as, for example, aluminum
oxides, silicates, zirconium oxides, titanium oxides,
boron nitrides, silicon nitrides, boron carbides, mixed
silicon-aluminum nitrides, and metal titanates;
magnetic materials, such as, for example, magnetic
oxides of transition metals, such as iron oxides,
cobalt doped iron oxides, and ferrites; metals, such
as, for example, iron, nickel, cobalt, and their
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alloys; and biocides, agrochemicals, and drugs, such as
fungicides, for example.
The composition of the invention can be used for
producing paints and varnishes.
In the examples set out hereinbelow, the present
invention is described by way of example, without any
intention that the invention, whose breadth of
application is evident from the entire description and
the claims, should be confined to the embodiments
stated in the examples.
Example 1:
A three-necked flask equipped with stirrer,
thermometer, reflux condenser, nitrogen introduction
tube, and dropping funnel was charged under an N2
atmosphere with 46.57 g of benzyl methacrylate, 150 g
of butyl acetate, 1.25 g of copper(I) oxide, and 3.2 g
of PMDETA (N,N,N',N",N"-pentamethyldiethyl enetriamine).
The solution was heated to 90 C. Subsequently, at the
same temperature, 3.2 g of ethyl bromoisobutyrate were
added. After a reaction time of 2 hours, a mixture of
20.77 g of dimethylaminoethyl methacrylate (DMAEMA) and
75.06 g of methoxypolyethylene glycol 500 methacrylate
(MPEG 500 MA from Evonik Rohm GmbH, CAS No.: [26915-72-
0]) was added, and stirring was continued at 90 C for 3
hours more. This was followed by a further hour of
stirring, at 100 C. To terminate the reaction,
atmospheric oxygen was introduced for approximately 15
minutes, and 3.22 g of n-dodecyl mercaptan were added.
After an hour of stirring, the precipitate was filtered
off by means of superatmospheric pressure filtration,
through a filter from Beko (type: KD-10). On a rotary
evaporator, the solvent was stripped from the light
yellow filtrate at a temperature of 100 C and at
2 mbar. The light yellow, viscous residue is the
desired product.
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Example 2:
A three-necked flask equipped with stirrer,
thermometer, reflux condenser, nitrogen introduction
tube, and dropping funnel was charged under an N2
atmosphere with 20.02 g of benzyl methacrylate, 150 g
of butyl acetate, 1.1 g of copper(I) oxide, and 2.7 g
of PMDETA (N,N,N',N",N"-pentamethyldiethyl enetriamine).
The solution was heated to 90 C. Subsequently, at the
same temperature, 2.7 g of ethyl bromoisobutyrate were
added. After a reaction time of 2 hours, a mixture of
26.75 g of dimethylaminoethyl methacrylate (DMAEMA) and
96.66 g of methoxypolyethylene glycol 500 methacrylate
(MPEG 500 MA from Evonik Rohm GmbH, CAS No.: [26915-72-
0]) was added, and stirring was continued at 90 C for 3
hours more. This was followed by a further hour of
stirring, at 100 C. To terminate the reaction,
atmospheric oxygen was introduced for approximately 15
minutes, and 2.8 g of n-dodecyl mercaptan were added.
After an hour of stirring, the precipitate was filtered
off by means of superatmospheric pressure filtration,
through a filter from Beko (type: KD-10). On a rotary
evaporator, the solvent was stripped from the light
yellow filtrate at a temperature of 100 C and at
2 mbar. The light yellow, viscous residue is the
desired product.
Example 3:
A three-necked flask equipped with stirrer,
thermometer, reflux condenser, nitrogen introduction
tube, and dropping funnel was charged under an N2
atmosphere with 20.47 g of benzyl methacrylate, 150 g
of butyl acetate, 0.55 g of copper(I) oxide, and 1.40 g
of PMDETA (N,N,N',N",N"-pentamethyldiethyl enetriamine).
The solution was heated to 90 C. Subsequently, at the
same temperature, 1.40 g of ethyl bromoisobutyrate were
added. After a reaction time of 2 hours, a mixture of
20.47 g of dimethylaminoethyl methacrylate (DMAEMA) and
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98.83 g of methoxypolyethylene glycol 500 methacrylate
(MPEG 500 MA from Evonik Rohm GmbH, CAS No.: [26915-72-
0]) was added, and stirring was continued at 90 C for 3
hours more. This was followed by a further hour of
stirring, at 100 C. To terminate the reaction,
atmospheric oxygen was introduced for approximately 15
minutes, and 1.42 g of n-dodecyl mercaptan were added.
After an hour of stirring, the precipitate was filtered
off by means of superatmospheric pressure filtration,
through a filter from Beko (type: KD-10). On a rotary
evaporator, the solvent was stripped from the light
yellow filtrate at a temperature of 100 C and at
2 mbar. The light yellow, viscous residue is the
desired product.
Example 4:
A three-necked flask equipped with stirrer,
thermometer, ref lux condenser, nitrogen introduction
tube, and dropping funnel was charged under an N2
atmosphere with 9.50 g of benzyl methacrylate, 150 g of
butyl acetate, 0.74 g of copper(I) oxide, and 1.87 g of
PMDETA (N,N,N',N",N"-pentamethyldiethylenetriamine).
The solution was heated to 90 C. Subsequently, at the
same temperature, 1.87 g of ethyl bromoisobutyrate were
added. After a reaction time of 2 hours, a mixture of
29.49 g of dimethylaminoethyl methacrylate (DMAEMA) and
106.54 g of methoxypolyethylene glycol 500 methacrylate
(MPEG 500 MA from Evonik Rohm GmbH, CAS No.: [26915-72-
0]) was added, and stirring was continued at 90 C for 3
hours more. This was followed by a further hour of
stirring, at 100 C. To terminate the reaction,
atmospheric oxygen was introduced for approximately 15
minutes, and 1.90 g of n-dodecyl mercaptan were added.
After an hour of stirring, the precipitate was filtered
off by means of superatmospheric pressure filtration,
through a filter from Beko (type: KD-10). On a rotary
evaporator, the solvent was stripped from the light
yellow filtrate at a temperature of 100 C and at
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2 mbar. The light yellow, viscous residue is the
desired product.
Performance testing:
Test pigments:
From the multiplicity of possible solids, the following
commercial pigments were selected: Printex 95
(manufacturer: Evonik Industries AG) as carbon black
pigment, Heliogenblau L7101F (manufacturer: BASF AG),
Bayferrox 120M and Bayferrox 3920 (manufacturer:
Bayer AG) as typical color pigments.
White tint:
For producing the paints, a white tint with the
following composition is used:
a) preparation of a white paste (Table 1):
Initial mass [g]
TD755Wa) 17.4
demineralized water 39.6
Foamex 810b) 2.0
Parmetol K 40c) 0.2
Aerosil 200d) 0.6
Kronos 2310e) 140.0
Total 200.0
a) dispersing additive, trade name of Evonik
Industries AG
b) defoamer, trade name of Evonik Industries AG
c) biocide, trade name of Schilke & Mayr
d) Si02, trade name of Evonik Industries AG
e) titanium dioxide, trade name of KRONOS
International, Inc.
The ingredients of the formula are admixed, in
accordance with the above formula from Table 1, with
200 g of glass beads, and then shaken in a Skandex
mixer (type: DAS H 200-K from Lau GmbH) for 2 hours.
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The glass beads are subsequently separated from the
white paste by means of a sieve.
b) Preparation of the white paint (Table 2):
Initial mass [g]
White paste (as per 45.0
Table 1)
Neocryl XK 53.5
90/Texanol 97:3f)
Tego Wet KL 2459) 0.5
Visko Plus 3000h) 1.0
Total 100.0
f) binder, trade name of NeoResins
g) wetting agent, trade name of Evonik Industries AG
h) thickener, trade name of Evonik Industries AG
The formulation is stirred at moderate shear rate with
a dissolver for 15 minutes and then sieved through a
125 um sieve.
Preparation of the pigment pastes:
(Table 3):
Heliogenblau Printex Bayferrox(D Bayferrox
L7101F 95 120 M 3920
H20, demin. 50.0 g 67.0 g 23.2 g 38.5 g
Dispersing
additivea) 14.0 g 12.0 g 7.8 g 10.5 g
Foamex 830b) 1.00 g 1.00 g 1.00 g 1.00 g
Pigment 35.0 g 20.0 g 65 g 50 g
Sum total 100 g 100 g 100 g 100 g
a) copolymers from Examples 1-4, and amount of
dispersing additive based on a 100% product.
b) Defoamer, trade name of Evonik Goldschmidt GmbH
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The formula ingredients are weighed out in accordance
with the formulas above, from Table 3, into 250 ml
screw-top glass vessels, and glass beads are added
(200 g of glass beads to 100 g of millbase). The closed
glass vessels are then shaken in a Skandex mixer (type:
DAS H 200-K from Lau GmbH) for 2 hours. The glass beads
are subsequently separated from the pigment paste by
means of a sieve.
For testing, 1 g of each pigment paste and 20 g of
white tint are weighed out jointly. The mixture is
homogenized for 1 minute at 2500 rpm in a Speedmixer
(type: DAC 150 FVZ from Hauschild & Co. KG). The tinted
paints were applied using a spiral bar (100 rim) to a
contrast chart (Leneta ) and dried at room temperature.
Colorimetry:
Colorimetry on the paint blend (100 im film thickness
on Leneta contrast chart) took place using an
instrument from the company X-Rite (type: X-Rite
SP 60). For all samples the L*a*b* values were
determined in accordance with the CIE-Lab system
(CIE = Commission Internationale de 1'Eclairage). The
CIE-Lab system is useful, as a three-dimensional
system, for the quantitative description of the color
loci. Plotted in the system on one axis are the colors
green (negative a values) and red (positive a* values),
and, on the axis at right angles to this, the colors
blue (negative b* values) and yellow (positive b*
values). The value C* is made up of a* and b* as
follows: C* = (a*2+b*2)0*5 and is used to describe violet
color loci. The two axes intersect at the achromatic
point. The vertical axis (achromatic axis) is relevant
for the lightness, from white (L = 100) to black
(L = 0). Using the CIE-Lab system it is possible to
describe not only color loci but also color spacings,
by stating the three coordinates.
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The tristimulus value Y was determined in accordance
with the following formula (Y1):
Y- L`+16Y
116 j *100
(Yl)
The color strength F was determined in accordance with
the following formula (Y2):
F (100 - Y)2
2*Y
(Y2)
Rub-out test:
In order to make visible and measurable the vertical
floating, in particular, of pigments in coating films,
the test known as the rub-out test can be carried out.
For this test, the coating film still wet but having
already started to set, is rubbed with the finger or
with a brush. If the pigments have undergone separation
or are in a highly flocculated state, the mechanical
operation of rubbing forces them back into homogeneous
distribution. The target shade of the homogeneous
mixture is produced. The extent of the disruption is
evident from the color difference relative to the
unrubbed film. Both a positive and a negative rub-out
effect may be obtained. A positive rub-out effect means
that the color strength of the unrubbed film is lower
than that of the rubbed film, which may be
attributable, for example, to the floating of white
pigment. In the case of a negative rub-out effect, the
converse is the case.
Prior-art dispersants used were the following
dispersants Cl to C3:
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Cl: Disperbyk 2010 from BYK-Chemie GmbH
C2: EFKA 4585 from CIBA AG
C3: TEGO Dispers 750W from Evonik Industries AG
The pigment pastes were prepared as for Table 3, the
amount of dispersing additive and water being adapted
so that C1 and C3 were aqueous solutions with a
strength of approximately 40% by weight, and C2 was an
aqueous solution with a strength of approximately 50%
by weight.
Table 4: White tint with Printex 95 pigment paste:
Dispersing Lightness a* b* Rub-out Y F
additive L* DE
Example 1 54.03 -1.08 -4.59 1.51 22.00 138.24
Example 2 46.91 -0.94 -3.93 1.12 15.95 221.44
Example 3 45.11 -0.85 -3.46 1.19 14.62 249.30
Example 4 51.03 -1.05 -4.69 0.98 19.29 168.79
C1 47.32 -0.91 -3.36 1.07 16.26 215.54
C2 45.37 -0.84 -3.24 1.43 14.81 245.06
C3 46.49 -0.93 -3.93 1.13 15.63 227.64
It is evident that the polymer from Example 3 in
particular exhibits improved color strength relative to
the dispersing additives of the prior art.
Table 5: White tint with Heliogenblau 7101F pigment
paste:
Dispersing Lightness a* b* Rub-out Y F
additive L* AE
Example 1 63.25 -20.91 -35.66 0.27 31.89 72.74
Example 2 62.99 -21.33 -36.34 0.88 31.57 74.14
Example 3 61.28 -21.15 -37.28 0.80 29.57 83.88
Example 4 63.91 -20.61 -34.28 0.56 32.69 69.29
C1 62.33 -21.34 -36.89 1.23 30.79 77.79
C2 62.53 -21.62 -36.74 1.23 31.03 76.67
C3 61.45 -21.26 -37.00 0.50 29.76 82.87
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In the table above it is clear that the inventive
examples exhibit lower rub-out values and allow the
preparation of phthalocyanine pastes with high
stability. In the tinting shown, paints with high color
strength F result, particularly in Example 3.
Table 6: White tint with Bayferrox 3920 pigment paste:
Dispersing Lightness a* b* Rub-out Y F
additive L* AE
Example 1 84.65 6.90 26.52 0.21 65.32 9.20
Example 2 84.36 7.06 27.50 0.61 64.76 9.59
Example 3 81.56 8.41 30.32 0.91 59.49 13.79
Example 4 85.01 6.73 26.09 1.09 66.03 8.74
Cl 82.45 7.89 30.84 1.76 61.13 12.36
C2 82.85 7.72 30.23 1.46 61.88 11.74
C3 85.17 6.41 27.66 3.00 66.34 8.54
The performance capacity of the inventive dispersants
for finely divided pigments of the Bayferrox type is
emphasized in Table 6 by the lower rub-out values.
Table 7: White tint with Bayferrox 120 M pigment
paste:
Dispersing Lightness a* b* Rub-out Y F
additive L* AE
Example 3 63.94 21.63 8.57 0.83 32.73 69.14
Example 4 64.98 21.08 8.31 0.45 34.02 63.97
C3 65.49 21.04 8.29 0.70 34.67 61.56
The performance capacity of the inventive dispersants
for red pigments of the Bayferrox type is clear in
Table 7 through the higher color values relative to a
dispersing additive (C3) according to the prior art.
