Note: Descriptions are shown in the official language in which they were submitted.
CA 02246480 1998-08-12
PAT 96 595 02.09.1995
BASF Lacke + ~arben Aktiengesellschaft, Munster
Process for the preparation of aqueous coating com-
positions for the painting of vehicle interiors
Field of the invention
The invention relates to multistage processes for the
preparation of aqueous coating compositions BM for the
painting of vehicle interiors, comprising the following
stages:
I. preparation of a premix VM including a plgment-
containing component A), a binder-containing
component B) and a component C) which contains
crosslinking agent, or a rheology-controlling
component D),
and then
II. preparation of an aqueous coating composition BM
from the premix VM and the rheology-controlling
component D) or the component C) containing
crosslinking agent, provided these components are
not present in the premix VM, and final estab-
lishment of the processing viscosity of the
coating composition BM by addition of deionized
water as component ~).
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Prior art
Multicomponent mixer systems on an aqueous basis for
production-line autofinishing and/or for the refinish-
lng of damage sites, especially for automotiverefinishing, are known.
DE A-42 32 721 describes two-component mixer systems
consisting of different base paints, containing less
than 5~ by weight of water, at least one color and/or
special-effect pigment, organic solvent, optionally
auxiliaries and additives, and a water-dilutable
blnder, and consisting of a water-containing, pigment-
free component. The binders employed in the base paints
comprise at least one water-dilutable or water-
dispersible acrylicized polyurethane resin and/or at
least one water-dilutable or water-dispersible poly-
acrylate resin. The mixer systems described in
DE A 42 32 721 are preferably employed as aqueous
coating compositions for producing a basecoat film
After initial drying of the basecoat films produced in
this way, an appropriate transparent topcoat com-
position is applied. Suitable topcoats include both
organically dissolved and aqueous 1- or 2-component
clearcoats, and also transparent powder coatings. Use
is often made of 2-component clearcoats based on a
hydroxyl-containing acrylate copolymer and a polylso-
cyanate. Clearcoats of this kind are described, for
example, in DE-A-34 12 534, DE-A-36 09 519, DE-A
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37 31 552 and DE-A-38 2 3 oos. Suitable 1-component
clearcoats, based for example on a hydroxyl-containing
binder and an amino resin hardener, are likewise known
and are described, for example, in Kittel, Lehrbuch der
Lacke und Beschichtungen [Textbook of paints and
coatings], Volume IV, Verlag W.A. Colomb in der H.
Heeremann GmbH, Berlin-Oberschwandorf, 1976. In
general, after any flashing off period which may be
required, the basecoat is dried together with the
topcoat.
Object and achievement
The requirements in the painting of production-line
components or in automotive refinishing are based on
the high demands placed on such coatings in terms of
mechanical strength, for example against impact or
stone chipping, brilliant surface and weathering
stability, and are based in turn on the exterior finish
of automotive components.
Such requirements necessitate technologically complex
multicoat finishes, for example that described above
consisting of basecoat film and topcoat film, the
application of which is laborious. Automotive interior
finishes need satisfy only some of such requirements.
In particular, the stringent requirements placed on
mechanical strength, the brilliance of the paint
surface and the weathering stability are not as exact-
ing as in the case of exterior finishes. In contrast,
CA 02246480 1998-08-12
there are stringent requirements regarding the color
uniformity of interior and exterior finish.
The object of the present invention, therefore, was to
modify existing coating compositions, prepared, for
example, from mixer systems, for the production of
basecoat films in the exterior finishing of vehicles in
such a way that it is possible for the interior finish-
ing of vehicles to use constituents of such mixer
systems which insure, in particular, color uniformity,
and such that no topcoat films are necessary in the
case of interior finishing.
Surprisingly it has been found that aqueous coating
compositions BM for the painting of vehicle interiors,
which compositions conform outstandingly to the
criteria set out in stating the object, can be prepared
in a simple manner as follows:
I. a premix VM is prepared consisting of A) different
base paints (A) according to DE-A-42 32 721, and
comprising less than 5~ by weight of water, at least
one color and/or special-effect pigment, organic
solvents, and at least one water-dilutable or water-
dispersible hydroxyl-containing binder, preferably a
water-dilutable or water-dispersible hydroxyl-
csntaining polyacrylate resin (A2) having a hydroxyl
number of from 5 to 40 mg of KOH/g and/or at least one
water-dilutable or water-dispersible hydroxyl-
containing, optionally acrylicized polyurethane resin
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(A1) having a hydroxyl number of from 20 to 100 mg of
KOH/g, and of B) at least one aqueous, pigment-free
component comprising at least one optionally hydroxyl-
containing binder (B1), and of C) a solution or
dispersion of a polyisocyanate (Cl) or of a mixture of
polyisocyanates (C1) or, alternatively to C), of D) an
aqueous solution or dispersion of a rheological
auxiliary (D1),
and then
II. in order to prepare the aqueous coating composition
sM, as component D) an aqueous solution or an aqueous
dispersion or an aqueous solution [sic] of a rheologi-
cal auxiliary (D1) or, alternatively, as component C) asolution or a dispersion of a polyisocyanate (C1) or of
a mixture of polyisocyanates (C1) is admixed to the
premix VM, provided the respective component C) or D)
is not present in the premix VM, and finally the
processing viscosity of the aqueous coating composition
sM is established by adding deionized water as com-
ponent E).
The spray paints produced in this way can be employed
for vehicle interior painting without additional
application of a topcoat.
The base paints (A) used in component A) are preferably
free from water.
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The di- and/or polyisocyanates (C') or their mixtures
which are employed are preferably isomers or lsomer
mixtures of aliphatic and/or cycloaliphatic and/or
aromatic di- and/or polyisocyanates in organic or
aqueous solution or in organic or aqueous dispersion.
Implementation of the invention
Ihe ~ nt~ of the aqueous coating composition BM
Ihe constituents of c _ ~~t A)
Component A) of the mixer system can include all
customary paint pigments provided that they do not
react with water within a short time, for example
within the period of time between preparing the aqueous
coating compositions BM according to the novel process
and the application of the aqueous coating
compositions, and that they do not dissolve in water.
This component A) may include special-effect pigments
and/or color pigments based on inorganic or organic
compounds. In order to insure a scope for use which is
as universal as possible and to be able to realize the
maximum possible number of shades, it is preferred to
construct as component A) a mixer system based on
components containing only color pigments and
components containing only speclal-effect pigments.
For preparing component A) it is possible to use all
special-effect pigments which are customarily employed
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ln the formulation of aqueous coating compositions.
Examples of suitable special-effect pigments are com-
mercially available aluminum bronzes, the aluminum
bronzes chromated according to DE-A-36 36 183,
S stainless-steel bronzes and other customary metal flake
or metal platelet pigments. Pearlescent and
interference pigments are also suitable as special-
effect pigments.
Examples of color pigments based on inorganic compounds
are titanium dioxide, iron oxides, carbon blacks and
others Examples of organic color pigments are
Indanthrene blue, Chromophthal red, Irgazine orange,
Sicotrans yellow, Heliogen green and others.
Preferred hydroxyl-containing binders for use in com-
ponent A) are the water-dilutable or water-dispersible,
optionally acrylicized polyurethanes (A1) and/or poly-
acrylates (A2) already mentioned, which are customarily
employed in aqueous coating compositions and can be
prepared in organic form. In this context, the
dilutability or dispersibility of the resins in water
can also be adjusted by using appropriate solubilizers
as cosolvent and/or solvent. Critical factors for the
selection of the binders are, on the one hand, good
stability on storage in organic solution, including in
particular the ability to avoid settling of the pig-
ments, and, if appropriate, on the other hand, the
ability for the base paint to be incorporated into
component B), or vice versa, without problems.
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optionally acrylicized polyurethanes (Al) of this k;nd
which are used as binders in component A) of the novel
coating composition, and their preparation, are des-
cribed in, for example, DE-A-40 10 176.
The optionally acrylicized polyurethane (A1) is prefer-
ably prepared by well-known methods of polyurethane
chemistry from the building blocks (Aiia) to (Aiif)
described in DE-A-42 32 721.
The molecular weight of the polyurethane resins car. -
as the person skilled in the art is aware - be
controlled in particular by the proportion and the
functionality of the starting compounds employed
according to DE-A-42 32 721.
The polyurethane resins can be prepared both in bulk
and in organic solvents.
A detailed description of the reaction, of the nature
and of the quantities to be employed of building blocks
(Aiia) to (Aiif) can be taken from DE-A-42 32 721
In accordance with DE-A-42 32 721 the acrylic}zed
polyurethane resins (Al') are prepared by making ready
a solution of the polyurethane resin (Al) in an organic
solvent or an organic solvent mixture and, in this
solution, polymerizing ethylenically unsaturated mono-
mers or a mixture of ethylenically unsaturated monomers
in a free-radical polymerization, and converting the
reaction product thus obtained into an aqueous disper-
s on. As ethylenically unsaturated monomers it is
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possible in accordance with DE-A-42 32 721 to employ
virtually all free~radically polymerizable monomers,
but subject to the customary restrictions for copoly-
merizations as laid down by the Q and e scheme of
Alfrey and Price and/or by the copolymerizat-on
parameters (cf. e.g. Brandrup and Immergut, Polymer
Handbook, 2nd ed. John Wiley + Sons, New York (1975)).
A detailed listing of the ethylenically unsaturated
monomers can be taken from DE-A-42 32 721.
The polymers employed in accordance with the invention
and prepared according to DE-A-42 32 721 must contain
groups capable of forming anions, which groups are
neutralized prior to or during the transfer of the
polymers from the organic solvent or solvent mixture to
water and which enable the formation of stable aqueous
dispersions. The polymers in question can, in addition to
the groups capable of forming anions, also contain other
nonionic stabilizing groups, for example poly(oxy-
alkylene) groups, especially poly(oxyethylene) and/orpoly(oxypropylene) and/or poly(oxyethylene)(oxypropylene)
groups.
The introduction of the groups capable of forming
anions into the polymers in question is described, for
example, in DE-A-42 32 721.
Additionally preferred as water-soluble or water-
dispersible binder component of component A) of the
novel mixer system are water-dilutable or water-
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àispersible polyacrylate resins (A2) as described, for
example, in DE-A-42 32 721.
The sum of the proportions by weight of the monomeric
components of the polyacrylate resin (A2) which are
described in DE-A-42 32 721 are [sic] selected in
nature and quantity [sic] such that the polyacrylate
resin (A2) has a hydroxyl number of from 5 to 40,
preferably from 5 to 35 mg of KOH/g, and an acid number
of from 20 to 100, preferably from 25 to 50 mg of KOH/g
and a glass transition temperature (TG) Of from
40 degrees C to +60 degrees C, preferably from
-20 degrees C to +40 degrees C.
A detailed description of the monomers and of the
preparation of the polyacrylate resins (A2) can be
taken from DE-A-42 32 721.
As binders in components A) it is of course also
possible to employ mixtures of the said binders (Al)
and (A2) and, in addition, other water-dilutable or
water-dispersible binders, preferably containing
hydroxyl groups.
It is essential to the invention that the base paints
(A) are essentially free from water, preferably
completely free from water. The water content of the
base paints (A) should be less than 5~ by weight, based
on th.e overall weight of the base paint (A).
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As solvents the base paint (A) contains one or more
organic solvents. Examples of suitable solvents are, in
particular, water-soluble or water-dilutable solvents,
for example alcohols, esters, ketones, keto esters,
glycol ether esters and the like. Preference is given
to employing alcohols and glycol ethers, particularly
preferably butylglycol and butanols
In this case there is the possibility, as described in
DE-A-42 32 721, of employing during the actual
preparation of the binders solvents which also remain
subsequently as solvents in the base paint More
frequently, however, the binders are prepared using a
different solvent which following binder preparation is
distilled off gently by means of vacuum distillation or
thin-film evaporation and is replaced by a solvent
which remains in the binder solution which is then
employed in the base paint. Higher-boiling solvents
should be soluble in water and remain in the poly-
urethane resin solution employed in the base paint in
order to facilitate the coalescence of the polymer
particles during film formation.
Component A) may additionally comprise from 0 to 10% by
weight, based on A), of customary auxiliaries and
additives.
Examples of such additives are defoamers, dispersion
auxiliaries, emulsifiers, leveling agents and others.
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Component A) preferably contains
Aa) from 0.5 to 70~ by weight of at least one special-
effect pigment and/or at least one color pigment,
Ab) from 10 to 80~ by weight of at least one water-
dilutable or water-dispersible, hydroxyl-contain-
ing binder,
Ac) at least one organic solvent, and optionally
Ad) auxiliaries and additives,
the sum of the proportions by weight of components Aa)
to Ad) making up in each case 100~ by weight of
component A).
With particular preference component A) is composed of
base paints (A') containing only special-effect pig-
ments and of base paints (A'') containing only colorpigments.
Particularly preferred base paints (A') based on
special-effect pigments contain
Aa) from 0.5 to 50~ by weight of at least one special-
effect pigment,
Ab) from 20 to 80~ by weight of the water-dilutable or
water-dispersible, hydroxyl-containing binder, and
Ac) at least one organic solvent,
the sum of the proportions by weight of components Aa)
to Ac) being in each case 100~ by weight.
Particularly pre~erred base paints (A' ' ) based on
lnorganic color pigments contain
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Aa) from 1 to 70% by weight of at least one inorganic
color pigment,
Ab) from 10 to 80~ by weight of at least one water-
dilutable or water-dispersible, hydroxyl-contain-
ing binder, and
Ac) at least one organic solvent,
the sum of the proportions by weight of components Aa)
to Ac) being in each case 100~ by weight.
Particularly preferred base paints (A'') based on
organic color pigments contain
Aa) from 1 to 30~ by weight of at least one organic
color pigment,
Ab) from 10 to 80~ by weight of at least one water-
dilutable or water-dispersible, hydroxyl-contain-
ing binder, and
Ac) at least one organic solvent,
the sum of the proportions by weight of components Aa)
to Ac) being in each case 100~ by weight.
It is of course also possible to employ base paints (A)
containing a combination of at least one organic color
pigment and at least one inorganic color pigment.
Regarding further criteria for the base paints (A),
reference may be made to DE-A-41 10 520.
Component A) is prepared in accordance with methods
known to the person skilled in the art, by mixing and,
if appropriate, dispersing the individual components.
Eor instance, color pigments are usually incorporated
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by dispersing the respective pigments with one or more
of the above-described binders, which are preferably
employed in the form of their solutions in organic
solvents. If desired, further organic solvent can be
added for dispersing. These pigments are dispersed with
the aid of customary apparatus, for example bead mills
and sand mills.
The special-effect pigments are usually incorporated by
homogeneously mixing the special-effect pigments with
one or more solvents. This mixture is then incorporated
by stirring into a mixture of one or more of the above-
described binders, with or without the addition of
further organic solvents, by means of a stirrer or
dissolver. The binders are preferably employed in the
form of their solutions in organic solvents.
The respective proportions of pigment, binder and
solvent depend in this instance, as familiar to the
person skilled in the art, on the flow behavior of the
pigment paste, and are therefore dependent on the
particular pigment used.
A detailed description of the preparation of component
A) can be taken from DE-A-4I 10 520.
The constituents of rl Pnt B)
The aqueous component s) is free from pigment and
contains at least one binder (BI). If desired, com-
ponent B) can also contain further auxiliaries and
additives, one or more water-dilutable or water-
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dispersible blnders, and organic solvents.
Suitable binders (B1) for use in component B) are
preferably the water-dilutable or water-dispersible,
hydroxyl-containing polyacrylate resins (A2) and the
water-dilutable or water-dispersible, hydroxyl-contain-
ing, optionally acrylicized polyurethane resins (A1)
already described in connection with the description of
component A), and also, furthermore, amino resins,
polyester resins, different polyacrylate resins and
different polyurethane resins which are dilutable or
dispersible in water and preferably contain hydroxyl
groups.
~hen used in component B) these binders (B1) can be
employed not only as organic solution but also,
preferably, in a water-containing form. The transfer of
the resins into the aqueous phase is carried out, for
example, by neutralizing the carrier groups (groups
capable of forming anions or cations, for example
carboxyl groups), and then carrying out dilution with
water, with or without the prior partial removal of the
organic solvent employed in preparing the resin, or by
direct synthesis of the resin in the presence of water.
Eor further details reference may be made to the
literature in which the preparation of the resins is
described (cf. e.g. DE-A-32 10 051,DE-A-26 24 442,
DE-A-37 39-332, US-A-4,719,132, EP-A-89 497,
US-A-4,558,090, US-A-4,489,135,EP-A-38 127,
DE-A-36 28 124, EP-A-158 099,DE-A-29 26 584,
EP-A-195 931 and DE-A-33 21 180).
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Also suitable as binders (Bl) for component B) are
water-dilutable or water-dispersible polyurethane
resins which cannot be prepared in the form of organic
solutions. Such resins are, in particular, polyurethane
resins in which the isocyanate group-containing pre-
polymer has been reacted with a polyamine as modifying
agent. The preparation of these polyurethane resins is
described, for example, in DE-A-42 32 721.
lo Also suitable as water-dilutable or water-dispersible
binders (Bl) for component B) are the water-dilutable
emulsion polymers described in DE-A-38 41 540. For
further details reference is made to DE-A-38 41 540.
The aqueous component B) can, moreover, optionally
lnclude one or more organic solvents in minor amounts
and also, if desired, further customary auxiliaries and
additives. Examples of suitable organic solvents are
the solvents already listed in the description of
component A). The content of organic solvent is usually
from 0 to 3~ by weight, based on the overall weight of
component B).
Examples of suitable auxiliaries and additives are
likewise the additives mentioned in the description of
component A). The quantity of these additives for use
is usually from 0 to 10~ by weight, based on the
overall weight of component s).
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The constituents of component C)
Component C) contains at least one crosslinking agent
(Cl) based on di- or polyisocyanates or comprssing
mixtures thereof. In this context it is possible in
principle also to employ the compounds already
mentioned in the case of the description of component
(Aiib), as crosslinking agents (Cl).
As crosslinking agent (Cl) it is possible to employ
aliphatic and/or cycloaliphatic and/or aromatic poly-
isocyanates. Examples of aromatic polyisocyanates are
phenylene diisocyanate, tolylene diisocyanate, xylylene
diisocyanate, biphenylene diisocyanate, naphthylene
diisocyanate and diphenylmethane diisocyanate.
Owing to their good resistance to ultraviolet light,
(cyclo)aliphatic polyisocyanates give rise to products
with a low tendency to yellow. Examples of cyclo-
aliphatic polyisocyanates are isophorone diisocyanate,
cyclopentylene diisocyanate and the hydrogenation
products of the aromatic diisocyanates, such as
cyclohexylene diisocyanate, methylcyclohexylene diiso-
cyanate and dicyclohexylmethane diisocyanate.
Aliphatic diisocyanates are compounds of the formula
OCN-(CR3 2 ) r-NCO
in which r is an integer from 2 to 20, in particular
from 6 to 8, and R3, ,which can be identical or
different, is hydrogen or a lower alkyl radical having
1 to 8 carbon atoms, preferably 1 or 2 carbon atoms.
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Examples thereof are trimethylene diisocyanate,
tetramethylene diisocyanate, pentamethylene diiso-
cyanate, hexamethylene diisocyanate, propylene diiso-
cyanate, ethylethylene diisocyanate, dimethylethyl
5 diisocyanate, methyltrimethylene diisocyanate and
trimethylhexane diisocyanate.
Another example of a preferred aromatic diisocyanate
(C1) is tetramethylxylene diisocyanate.
n addition to diisocyanates the crosslinking agent
(Cl) may also include a proportion of polyisocyanates
with functionalitles of more than two, for example
triisocyanates.
Triisocyanates which have proven suitable are products
produced by trimerization or oligomerization of diiso-
cyanates or by reaction of diisocyanates with
pGlyfunctional compounds containing OH or NH groups.
These include, for example, the biuret of hexamethylene
diisocyanate and water, the isocyanurate of hexa-
methylene diisocyanate, or the adduct of isophorone
diisocyanate with trimethylolpropane. The mean
functionality can be lowered if desired by adding
monoisocyanates. Examples of such chain-terminating
monoisocyanates are phenyl isocyanate, cyclohexyl
isocyanate and stearyl isocyanate.
The crosslinking agent (C1) can be employed on its own
as mixing component C), and preferably in solution or
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dispersion in a liquid solvent (C2). Suitable solvents
(C2) are preferably organic solvents which show no
reaction to the crosslinking agent. Examples which may
be mentioned of appropriate organic solvents (C2) are
esters, ketones, keto esters, glycol ether esters and
the like.
If water or water-dilutable solvents (C2) are to be
used, premixing with the crosslinking agent (C1) is
preferred in order, on the one hand, to establish the
lo viscosity in a desired manner and, on the other hand,
to avoid a reaction of the crosslinking agent with, for
example, the hydroxyl groups of the binders.
The constituents of component D)
Component D) consists essentially of an aqueous
solution or dispersion of a rheological auxiliary (D1).
The rheological auxiliary (D1) influences the applica-
tion properties of the novel aqueous coating
compositions in a highly critical manner. For example,
in the case of aqueous coating compositions containing
metal pigments, the orientation of the metal pigment
particles, and thus the achievable metallic effect,
depends quite essentially on the rheological properties
of the aqueous coating composition.
Preferred rheological auxiliaries (D1) employed are
phyllosilicates, which swell in water and form gels
which, under shear stress, exhibit a high flow limit
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and a low plastic viscosity.
Very particular preference is given to the use of
phyllosilicate dispersions according to DE-A-37 07 388,
which are obtainable from phyllosilicates, a protective
S colloid and an aqueous dispersing agent, the protective
colloid being a poly(propylene oxide) which contains no
hydrophobic end groups and has on average at least one
hydroxyl group per molecule.
The novel process for the preparation of the aqueous
coating compositions BM, and their application
The novel process for the preparation of the aqueous
coating compositions for the painting of vehicle
interiors comprises the following stages:
In one embodiment of the invention
I. a premix VM is prepared preferably from 5 to 85% by
weight, particularly preferably from 10 to 75% by
weight, of the above-described pigment-containing
component A), preferably from 10 to 90% by weight,
particularly preferably from 15 to 85% by weight, of
the above-described binder-containing component B) and
preferably from 5 to 50% by weight, particularly
preferably from 10 to 40% by weight, of the above-
described component C) containing crosslinking agent,
the sum of components A), s) and C) making up 100% by
weight of the premix VM,
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and then
II. preferably from 10 to 9S~ by weight, particularly
preferably from 20 to 90~ by weight, of the premix VM
is mixed with preferably from S to 90~ by weight,
particularly preferably with from 10 to 80~ by weight,
of the above-described rheology-controlling component
D) to form the aqueous coating composition BM, the sum
of the premix VM and of the component D) making up 100%
by weight of the aqueous coating composition BM, and
finally the processing viscosity of the aqueous coating
composition is established, preferably at from 15 to
40 seconds (DIN4 cup), by adding deionized water as
component E).
In a further embodiment of the invention, of equal
status,
I. a premix VM is prepared preferably from 5 to 85~ by
weight, particularly preferably from 10 to 75~ by
weight, of the above-described pigment-containing
component A), preferably from 10 to 90~ by weight,
particularly preferably from 15 to 85~ by weight, of
the above-described binder-containing component B) and
preferably from 5 to 85% by weight, particularly
preferably from 10 to 75~ by weight, of the above-
described rheology-controlling component D), the sum of
components A), B) and D) making up 100~ by weight of
the premix VM,
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and then
II. preferably from 50 to 95~ by weight, particularly
preferably from 60 to 90~ by weight, of the premix VM
is mixed with preferably from 5 to 50~ by weight,
particularly preferably with from lO to 40~ by weight,
of the above-described component C) containing
crosslinking agent to form the aqueous coating
composition BM, the sum of the premix VM and of the
component C) making up 100~ by weight of the aqueous
coating composition BM, and finally the processing
viscosity of the aqueous coating composition BM is
established, preferably at from 15 to 40 seconds (DIN4
cup), by means of deionized water as component E).
The premix VM and the novel aqueous coating composition
BM are prepared by methods known to the person skilled
in the art, by mixing and, if desired, dispersing the
individual components.
The aqueous coating compositions BM prepared using the
novel mixer system are preferably applied in vehicle
interiors to substrates prepared in accordance with the
prior art, for example in production-line autofinishing
2s and, in particular, in automotive refinishing.
A particular advantage is that the coatings with the
novel paints in vehicle interiors require no additional
coating by a transparent topcoat.
The aqueous coating compositions BM are applied
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directly after their preparation by the novel process
to the appropriately prepared damage site (for example
by means of filling and surfacers) by customary
methods, in particular by means of spray painting.
The film prepared in this way is cured at room tempera-
ture or by forced drying (e.g. 10 min at 60 degrees C,
80 degrees C or by IR drying). The dry film thicknesses
of the matt paint film are between 5 and 100,
preferably between 10 and 70 micrometers.
In the text below the invention is illustrated in more
detail with reference to working examples. All parts
and percentages are by weight unless expressly stated
otherwise.
Exa~ples
Exa~ple ~: Preparation of the base paints (A') and
(A'') for ~, , ~nt A)
Preparation of a polyurethane resin (Al) as binder for
the base paints (A') and (A''):
686. 3 g of a polyester having a number-average
molecular weight Mn of 1400 daltons, based on a
commercial unsaturated di~eric fatty acid (having an
iodine number of 10 mg of I2/g, a monomer content of
not more than 0.1~, a trimer content of not more than
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2~, an acid number of from l9S to 200 mg of KOH/g and a
hydrolysis number of from 197 to 202 mg of KOH/g),
isophthalic acid and hexanediol are charged, under a
protective gas, to a suitable reaction vessel with
stirrer, reflux condenser and feed vessel, and, in
succession, 10.8 g of hexanediol, 55.9 g of
dimethylolpropionic acid, 344.9 g of methyl ethyl
ketone and 303.6 g of 4,4'-di(isocyanatocyclohexyl)-
methane are added.
This mixture is held under reflux until the isocyanate
content has fallen to 1.0~. Then 26.7 g of trimethylol-
propane are added to the mixture and this mixture is
held under reflux until the viscosity is 12 dPas (in a
solution of resin:N-methylpyrrolidone = 1:1). Then
1378.7 g of butylglycol are added.
After a vacuum distillation in which the methyl ethyl
ketone is removed, the resin solution is neutralized
with 32.7 g of dimethylethanolamine.
The solids content of the resulting solution of the
polyurethane resin (A1) is 44~ by weight. The com-
position obtained is diluted with butylglycol, with
intense stirring, to a solids content of 41~ by weight.
Preparation of the ba~e paint (A'):
20 parts by weight of an aluminum bronze chromated in
accordance with DE-A-36 36 183 (aluminum content 65~,
average particle diameter: 15 micrometers) are
dispersed homogeneously in 9 parts by weight of
CA 02246480 1998-08-12
butylglycol and 7 parts by weight of isobutanol by
stirring for lS minutes, and this dispersion is then
mixed with stirring into 64 parts by weight of the
solution of the polyurethane resin (A1) This mixture
is stirred for a further 30 minutes using a high-speed
stirrer at 1000 rpm.
Preparation of the base paint (A''):
8 parts by weight of Paliogen blue, 73.5 parts by
weight of the solution of the polyurethane resin (A1),
10.5 parts by weight of butylglycol and 8 parts by
weight of isobutanol are mixed with stirring and
dispersed using a sand mill.
Example 2: Preparation of c , ~t B)
2reparation of the binder (31) for component B):
686.3 g of a polyester having a number-average
molecular weight Mn of 1400 daltons, based on a
commercial unsaturated dimeric fatty acid (having an
iodine number of 10 mg of I2/g, a monomer content of
not more than 0 1~, a trimer content of not more than
2~, an acid number of from 195 to 200 mg of KOH/g and a
hydrolysis number of from 197 to 202 mg of KOH/g),
isophthalic acid and hexan~iol are charged, under a
protective gas, to a suitable reaction vessel with
stirrer, reflux condenser and feed vessel, and, in
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succession, 10.8 g of hexanediol, 55.9 g of
dimethylolpropionic acid, 344.9 g of methyl ethyl
ketone and 303.6 g of 4,4'-di(isocyanatocyclohexyl)-
methane are added.
This mixture is held under reflux until the isocyanate
content has fallen to l.0~. Then 26.7 g of trimethylol-
propane are added to the mixture and this mixture is
held under reflux until the viscosity is 12 dPas (in a
solution of resin:N-methylpyrrolidone = 1:1).
By adding 47.7 g of butylglycol, any excess isocyanate
present is destroyed.
Then 32.7 g of dimethylethanolamine, 2688.3 [lacuna]
deionized water and 193.0 g of butylglycol are added to
the reaction mixture with vigorous stirring.
After removing the methyl ethyl ketone by vacuum
distillation, the dispersion of the polyurethane resin
(B1) is obtained with a solids content of about 27~.
Preparation of co~ponent 8):
52 parts by weight of deionized water, 0.5 part by
weight of a commercial defoamer and 3.5 parts by weight
of a 3.5~ strength solution of a commercial poly-
acrylate thickener in water are added with stirring to
44 parts by weight of the dispersion of the
polyurethane resin (B1).
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Example 3: Preparation of the aqueous coating com-
position BMl by the process according to
claim 1:
Stage I:
121.9 parts by volume of the base paint (A') of Examp e
1 and 49.6 parts by volume of the base paint (A'') o-
Example 1 are mixed as component A), with inter.se
stirring, with 351.1 parts by volume of component B) of
Example 2 and 200 parts by volume of an isocyanate
curing agent (Glassodur~ hardener "sehr kurz" [very
short] from BASF ~acke+Farben based on 1,6-hexa-
methylene diisocyanate) as component C). This gives the
premix VMl.
Stage II:
The premix VMl is admixed, with intense stirring, with
463.4 parts by volume of rheological auxiliary
(adjustment additive 93-E3 from Glasurit, based on an
inorganic sodium-magnesium phyllosilicate thickener) as
component D). This gives the intermediate mixture ZMl.
Finally, the intermediate mixture ZMl is admixed, with
intense stirring, with 200 parts by volume of deionized
water as component E). This gives the aqueous coating
composition BMl.
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Example 4: Preparation of the aqueous coating com-
position BM2 by the process according to
claim 2:
Stage I:
121.9 parts by volume of the base paint (A') of Example
1 and 49.6 parts by volume of the base paint (A'') of
Example l are mixed as component A), with intense
stirring, with 351.1 parts by volume of component B) of
Example 2 and 463.4 parts by volume of rheological
auxiliary (adjustment additive 93-E3 from Glasurit) as
component D). This gives the premix VM2.
Stage II:
The premix VM2 is admixed, with intense stirring, with
200 parts by volume of isocyanate curing agent
(Glassodur~ hardener "sehr kurz~ [very short] from BASF
Lacke+Farben AG) as component C). This gives the
intermediate mixture ZM2.
Finally, the intermediate mixture ZM2 is admixed, with
intense stirring, with 200 parts by volume of deionized
water as component E) This gives the aqueous coating
2s composition BM2.
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- 29 -
Example 5: Application of the aqueous coating com-
positions BM1 and BM2, and properties of
the resulting f;n; ~h~E
Directly after the preparation of the aqueous coatlng
compositions BM1 and BM2, they are sprayed (2 spray
passes with HLVP or standard spray gun) by well-known
metnods onto phosphated steel panels (bonder 132)
coated with a commercial electrodeposition coating and
a conventional (i.e. solvent-containing) or water-
cor.taining surfacer, and are dried, following a flash-
off time of 30 minutes, for a further 30 minutes at
60 degrees C The dry-film thickness of the aqueous
coa~lng compositions BM1 and BM2 is from about 20 to
25 micrometers.
The resulting paint films are matt and of high scratcn
resistance. In the context of the painting of vehicle
interiors, the shade of the paint film can be matched
precisely, by identical choice and combination of the
base paints, to the shade of the vehicle exterior
fir.ish, for which it is necessary to apply as further
coating a 2-component clearcoat as topcoat (compare for
example DE-A-41 10 520).
