Note: Descriptions are shown in the official language in which they were submitted.
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PAT 93 443 19.11.1993
BASF Lacke und Farben A~, MUnster
~ omponent paint system
The invention relates to a paint system composed of two
components and to the use of this paint system for the
production of automotive refinishes.
DE-A-41 10 520 describes a mixer system for the
production of aqueous automotive refinishes, which
system involves automotive refinishes being proAl~ce~ by
mixing a pigment-contA;~;ng base color, which contains
less than 5% by weight of water, with a pigment-free
aqueous component.
In the two-component paint system described in DE-A-
41 10 520 the pigment-contA;n;~g base colors have
unfavorable flow characteristics, which have an adverse
effect both on meterability and on miscibility with the
pigment-free aqueous component. One of the consequences
of this is that the precise match;ng of predetermined
colors is rendered more difficult.
The object of the present invention is to provide a
paint system composed of two components which does not
have the disadvantages described above.
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This object i8 achieved by the provision of a paint
~ystem composed of two components (I) and (II), which
i8 characterized in that component (I) comprises
(A) from 5 to 50%, preferably from 10 to 30%, by
weight of at least one binder
(B) from 0 to 20% , prefersbly from 0 to 5%, by weight
of at least one cro~81 ;n~;ng agent,
(C) from 0.5 to 60~, preferably from 0.5 to 40%, by
weight of at least one pigment
(D) from 5 to 80%, preferably from 10 to 70%, by
weight of water
(E) from 0 to 40%, preferably from 5 to 20%, by
weight of at lea~t one orgsnic solvent,
(F) from 0 to 5%, preferably from 0 to 2%, by weight
of at lea~t one rheology-controlling additive, snd
(G) from 0 to 10%, preferably from 2 to 5%, by weight
of at lea~t one further oo.lvel~tional psint
auxiliary,
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the ~um of the percentage~ by weight indicated for
component~ (A), (B), (C), (D), (E), (F) and (G) alway~
being 100% by weight, and component (II) comprises
(H) from 70 to 99%, preferably from 80 to 99%, by
weight of water
(J) from 0 to 10%, preferably from 0 to 2%, by weight
of at least one organic solvent,
(K) from 0.1 to 10%, preferably from 1 to 3%, by
weight of at least one rheology-controlling
additive, and
(L) from 0 to 10%, preferably from 0.5 to 3%, by
weight of at least one further ~ol.ve..tional paint
auxiliary,
the sum of the percentages by weight ; n~ c~ted for com-
ponent~ (H), (J), (~) and (L) always being 100% by
weight.
The advantages of the two-component paint ~y~tem
provided in accordance with the invention are in
particular that the components are readily meterable
and miscible, making the production of paints having
predetermined colors very ea~y. In many ca~es it i~ no
longer neces~ary to formulate the paints pro~n~ u~ing
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the paint system according to the invention to
proce~ing vificosity in an additional operation. A
further advantage lies in the high freeze-thaw
stability of component (I).
As constituent (A) in component (I) it iB possible to
employ all water-soluble or water-dispersible h;nAPr~
which are suitable for paints. In particular it is
possible to employ water-soluble or water-dispersible
polyurethane resins, polyester resins, polyacrylate
resins, polyacrylate resins prepared in the ~L~ ~ence of
polyurethane and/or polyester resins, or mixtures of
these resins as constituent (A) in component (I).
15 Bxamples of suitable polyurethane resins are described
in the following documents: EP-A-355 433, DE-A-
35 45 618, DE-A-38 13 866. t8ic] DE-A-32 10 051, DE-A-
26 24 442, DE-A-37 39 332, US-A-4,719,132, BP-A-89 497,
US-A-4,558,090, US-A-4,489,135,, tsic~ DE-A-36 28 124,
EP-A-158 099, D8-A-29 26 584, ~P-A-195 931, DE-A-
33 21 180 and DE-A-40 05 961.
A~ constituent (A) in component (I) it i~ preferred to
employ polyurethane res~ns which have a number-average
molecular weight (determined by gel permeation
chromatography usinq polystyrene as stAnAArd) of from
1000 to 30,000, preferably from 1500 to 20000, and an
acid number of from 5 to 70 mg of KOH/g, preferably
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from 10 to 30 mg of KOH/g, and which can be prepared by
reacting prepolymers which contain isocyanate groups
with compound~ which are reactive toward isocyanate
groups .
The preparation of prepolymers contA ~ n ~ nq i~ocyanate
groups can be effected by reacting polyols having a
hydroxyl number of from 10 to 1800 mg, preferably from
50 to 1200 mg of ROH/g, with excess polyisocyanates at
temperatures of up to 150C, preferably from 50 to
130C, in organic solvents which are incapable of
reacting with isocyanates. The ratio of equivalents of
NCO to OH groups i8 between 2.0:1.0 and > 1.0:1.0,
preferably between 1.4:1 and 1.1:1.
The polyols employed for the preparation of the
prepolymer may be of low and/or high molecular weight
and may contain groups which are slow to react and are
anionic or are capable of forming anions. It iB also
possible to make partial use of low molecular weight
polyols having a molecular weight of from 60 to 400 in
order to prepare the prepolymers which contain
isocyanate yLGu~ , in which case quantities of up to
30% by weight of the overall polyol oonstituents,
preferably from about 2 to 20% by weight, are employed.
To obtain an NCO prepolymer of high fleY; h; 1 ~ ty a high
proportion should be added of a predominantly linear
polyol having a preferred 0~ number of from 30 to
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150 mg of KOH/g. Up to 97% by weight of the overall
polyol may consist of ~aturated and unsaturated
polyesterfi and/or polyethers having a molecular mass Mn
of from 400 to 5000. The polyether diols chosen should
not introduce excessive quantities of ether groups,
since otherwise the polymers formed swell in water.
Polye~ter diols are prepared by esterification of
organic dicarboxylic acid~ or their anhydride~ with
organic diols, or are derived from a hydroxycarboxylic
acid or from a lactone. In order to prepare branched
polyester polyols, a minor proportion of polyols or
polycarboxylic acids having a higher functionality can
be employed.
Typical multifunctional isocyanates which are employed
are aliphatic, cycloAl;phAtic and/or aromatic
polyisocyanates having at least two isocyanate groups
per molecule. Preference is given to the isomers or
isomer mixtures of organic diisocyanates. Because of
their good resistance to ultraviolet light,
(cyclo)~l;phAtic d~isocyanates give products having a
low tendency to yellowing. The polyisocyanate component
u~ed to form the prepolymer may also contain a
proportion of polyisocyanates of higher functionality,
provided that this does not bring about any gelling.
Products which have proven suitable as triisocyanates
are those obt~;~e~ by trimerization or oligomerization
of diisocyanate~ or by reaction of diisocyanates with
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polyfunctional compounds which contain OH or N~ groups.
If desired, the average functionality can be lowered by
addition of monoisocyanates.
Example6 of polyisocyanates which can be employed are
phenylene diisocyanate, tolylene diisocyanate, xylylene
diisocyanate, bisphenylene diisocyanate, naphthylene
diisocyante, ~;ph~nylmethane diisocyanate, i~ophorone
diisocyanate, cyclopentylene diisocyanate,
cyclohexylene diisocyanate, methylcyclohexylene
diisocyanate, dicyclohexylmethane ~ ocyanate,
trimethylene diisocyanate, tetramethylene diisoayanate,
pentamethylene diisocyanate, hexamethylene
diisocyanate, propylene diisocyanate, ethylethylene
diisocyanate and trimethylhexane diisocyanate.
Polyurethanes are generally incompatible with water
unless during their synthesis specific constituents are
incorporated and/or particular preparation steps are
carried out. Thus, in order to prepare the polyurethane
resins, it iB possible to use compo~n~ which contsin
two H-active groups which are reactive with isocyanate
group~, and at least one group which ensure~
dispersibility in water. Suitable groups of this kind
are nonionic ylou~s (e.g. polyethers), anionic yLO
mixtures of these two yLOup~ ~ or cationic y ou~_.
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To introduce anionic groups into polyurethane resin
molecules, compounds are used which contain at least
one group which i~ reactive toward isocyanate groups
and at least one group which is cApAhle of forming
anions. Suitable group6 which are reactive toward
i~ocyanate groups are in particular hydroxyl group~,
and also primary and/or secondary amino groups. Groups
capable of forming An;on~ are carboxyl, sulfonic acid
and/or phosphonic acid groups. Preference is given to
employing Alk~noic acids having two substituent~ on the
carbon atom. The substituent may be a hydroxyl group,
an alkyl group or an alkylol group. These polyols have
at least one, generally from 1 to 3, carboxyl y~Gu~- in
the molecule. They have from two to about 25,
preferably from 3 to 10 carbon atoms. The carboxyl-
contA;n;ng polyol may make up from 3 to 100% by
weight, preferably from 5 to 50% by weight, of the
overall polyol constituent in the NC0 prepolymer.
The isocyanate y~GU~B of the prepolymer which contains
isocyanate groups are reacted with a modifying agent.
In this context the modifying sgent is preferably added
in a quantity 80 aB to re~ult in chain exten~ions and
therefore in increa~e~ in molecular weight. The
modifying agents preferably employed are organic
compound~ which contain hydroxyl and/or ~econdary
and/or primary amino yLG~, especially di-, tri-
and/or polyols of higher functionality. Exsmple [sic]
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g
of polyols which can be employed are trimethylol-
propane, 1,3,4 butanetriol [ BiC ], glycerol, erythritol,
mesoerythritol, arabitol, adonitol, etc.
Trimethylolpropane is preferably employed.
As constituent (A) in component (I) it is possible in
principle to employ all water-soluble or water-
dispersible polyacrylate resins which are suitable for
aqueous paints. A very large number of such resins has
been described, and a very wide selection of them is
available commercially. Particularly suitable
polyacrylate resins are described in DE-A-38 32 826 and
in DE-A-38 41 540.
As constituent (A) in component (I) it is also possible
to employ water-soluble or water-dispersible polyester
resins.
A~ constituent (B) in component (I) it is possible, for
example, to employ blocked polyisocyanates and/or
water-soluble or water-dispersible am; no resins. It i~
preferred - if desired in the presence of cosolvents -
to employ water-soluble or water-dispersible melamine
resins. These are in general etherified
melamine/formaldehyde co~Ae~Ation products. The
solubility or dispersibility in water of the amino
resins depends, apart from the de~ ee of condensation,
which should be as low as possible, on the etherifying
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component, with only the lowest members of the alcohol
or of the ethylene glycol monoether series giving
condensation products which are soluble in water. The
melamine resins which are etherified with methanol have
S the greatest significance. If solubilizers are used, it
is also possible to disperse butanol-etherified
melamine resins in the aqueous phase. The possibility
also exists of incorporating carboxyl groups into the
conden~ation product. Transetherification products of
highly etherified co~pnsAtion products of formaldehyde
with hydroxycarboxylic acids, via their carboxyl
groups, are soluble in water after neutralization.
As constituent (C), components (I) may contain all
conventional paint pigments which do not react with
water or dissolve in water. The pigments may comprise
inorganic or organic compounds and may be effect
pigments and/or color pigments. In order to ensure a
degree of appl; ~Ah; lity which is as close as possible
to universal, and in order to maximize the possible
colors, it is preferred to incorporate, in one
component (I), either only color pigments or only
effect pigments, but not mixtures of color and effect
pigments.
Effect pigments which can be employed are metal flake
pigments such as commercial aluminum bronzes, aluminum
bronzes chromated in accordance with DE-A-36 36 183,
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and commercial stainless-steel bronzeg, and also
nonmetallic effect pigments such a~, for example,
pearle~cent or interference pigments. Example~ of
~uitable inorganic color pigments are titanium dioxide,
iron oxides, Sicotrans yellow and carbon black.
Examples of ~uitable organic color pigments are
indanthrene blue, Cromophthal red, Irgazin orange and
Heliogen green.
As constituent (E), component (I) may contain at least
one organic solvent. ~xamples of f uitable solvents are
in particular water-miscible ~olvents such as, for
example, alcohols, esters, ketones, keto ester~, glycol
ether esters and the like. Alcohols and glycol ethers
are preferably employed, and butyl glycol and butanols
are particularly preferred.
As constituent (F) component (I) may contain at least
one rheology-controlling additive. Examples of
rheology-controlling additives are crossl; nke~ polymer
microparticle~ as dif~closed, for example, in EP-A-
38 127, inorganic phyllosilicates, for example
aluminum-magnesium silicates, sodium-magnesium
phyllosilicates and f~odium-magnesium-fluorine-lithium
phyllosilicates of the montmorillonite type, and al~o
~ynthetic polymer~ cont~n~ng ionic y Gupf and/or
groups which have an a~sociated action, ~uch as
polyvinyl alcohol~ poly(meth)acrylAm~de,
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poly(meth)acrylic acid, polyvinylpyrrolidone,
styrene/maleic anhydride or ethylene/maleic anhydride
copolymers and derivatives thereof, or else
hydrophobically modified, ethoxylated urethanes or
polyacrylates. As rheology-controlling additives it is
preferred to employ inorganic phyllosilicates.
Particular preference i8 given to employing, as
rheology-controlling additive, a combination of a
polyacrylate resin which contains carboxyl yLUUp~
having an acid number of from 60 to 780 mg, preferably
from 200 to 500 mg of ROH/g, with a sodium-magne~ium
phyllosilicate.
~ he sodium-magnesium phyllosilicate is ~Ype~; ently
incorporated into the paint component in the form of an
aqueous paste. The paste preferably contain~ 3% by
weight of phyllosilicate and 3% by weight of
polypropylene glycol or 2% by weight of phyllosilicate
and 0.6% by weight of poly~Lo~lene glycol or 2% by
weight of phyllosilicate and 2% by weight of other
commercial, surface-active substances, all percentages
being based on the overall weight of the paste.
Component (I) of the paint ~ystem according to the
invention should preferably not contain any rheology-
controlling additive, especially not any inorganicphyllosilicate as rheology-controlling additive. The
rheology-controlling additives which are nece~sary for
the paints which can be prepared using the paint ~ystem
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according to the invention should preferably be
contained exclusively in component (II). It is
particularly preferred that, in the cases in which an
inorganic phyllosilicate i8 employed as rheology-
controlling additive, the inorganic phyllosilicate isexclusively contained in paint component (II).
As well as constituent (F), component (I) may also
contain, as constituent (G), at least one further
conventional paint additive. Examples of such additives
are antifoams, dispersion auxiliaries, emulsifiers and
leveling ass~stants.
Component (I) is prepared by methods known to the
person skilled in the art by mixing and, if desired,
dispersing the individual constituents. Thus, for
example, color pigments are conventionally incorporated
by dispersion of the respective pigments in one or more
binders. The dispersion of the pigments is carried out
using conventional devices such as, for example, bead
mills and sand mills.
The effect pigments are conventionally incorporated by
homogeneous mixing of the effect pigments with one or
more solvents. This mixture i6 then, using a stirrer or
di~solver, stirred into a mixture of one or more of the
above-described binders, if desired with the addition
of further organic solvent~.
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Constituent~ (J), (K) and (L) of paint component (II)
corre~pond to constituents (E), (F) and (G) of paint
component (I).
The paint sy~tem according to the invention is ~uitable
for the production of aqueous paints which are intended
to have a color determined precisely beforehand. By
mixing correspondingly pigmented paint components (I)
in proportions which are necessary to achieve the
corresponding colors, and adding paint component (II),
it is possible to obtain aqueous paints which are
accurate in color and can be processed immediately. The
paint system according to the invention is particularly
suitable for mixer systems for production of automotive
refinishes (cf. e.g. Glasurit-Handbuch, 11th Edition,
Kurt R., [BiC~ Vincentz-Verlag, Hanover 1984, pages 544
to 547). Using the paint system according to the
invention it is of course also possible to produce
paints for other areas of application, for example the
painting of plastic~ or the production-line fini~hing
of motor vehicle bodies.
The invention iB illustrated in more detail below with
reference to exemplary embodiments. In these
embodiment~ all ~ n~ tions as to parts and percentages
are by weight, unless expressly noted otherwise.
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1. PreParation of an organic Polyurethane resin
solution
686.3 g of a polyester having a number-average
molecular weight of 1400 based on a commercial
un~aturated 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), isophthAl;c
acid and heY~ne~;ol are placed under protective gas in
an appropriate reaction vessel with stirrer, reflux
condenser and feed vessel, and 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-(isocyanato-
cyclohexyl) methane are added in succession. This
mixture is maintA;~e~ under reflux until the isocyanate
content has fallen to 1.0%. Subsequently 26.7 g of
trimethylolpropane are added to the mixture, which is
maintained under reflux to a viscosity of 12 dPas (for
a solution of one part of resin solution in one part of
N-methylpyrrol~Q~e). 1378.7 g of butylglycol are then
added. After a vacuum distillation in which the methyl
ethyl ketone is removed, the resin solution is
neutralized with 32.7 g of dimethylethanol~m;ne. The
~olids content of the resulting resin solution is 44%.
Under intensive stirring, it is diluted to a solids
content of 41% by weight by A~; ng butylglycol.
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2. Preparation of an aqueous polyurethane resin
dispersion
686.3 g of a polyester having a number-average
molecular weight of 1400 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 KO~/g and a hydrolysis
number of from 197 to 202 mg of ROH/g), isophth~l;c
acid and hexanediol are placed under protective gas in
an appropriate reaction vessel with stirrer, reflux
conden~er and feed vessel, and 10.8 g of hexanediol,
55.9 g of dimethylolpropionic acid, 344.9 g of methyl
ethyl ketone and 303.6 tlacuna] of 4,4'-di-
(isocyanatocyclohexyl) methane are added in succession.
This mixture i8 maintained under reflux until the
i~ocyanate content has fallen to 1.0%. Subsequently
26.7 g of trimethylolpropane are added to the mixture,
which i8 maint~;ne~ under reflux to a viscosity of
12 dPas (for a solution of one part of resin solution
in one part of N-methylpyrrolidone). Any excess
isocyanate present is destroyed by ~ n~ 47 . 7 g of
butylglycol. Subsequently 32.7 g of dimethylethanol-
amine, 2688.3 g of deionized water and 193.0 g of
butylglycol are added to the reaction mixture with
vigorou~ stirring. After the removal of the methyl
ethyl ketone by vacuum distillation, an aqueous
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dispersion is obtained which has a solids content of
- about 27%.
3. Preparat~on of plgment pa~te~
3.1 PreParation of a pigment Paste contA;~; nq aluminum
pigment
15.5 part~ of an aluminum bronze chromated in
accordance with DE-A-36 36 183 (aluminum content 65%,
average particle diameter 15 ~m) are homogeneously
dispersed in 14 parts of butylglycol by stirring for 15
minutes and then run with stirring into a mixture of 51
parts of the polyurethane resin solution prepared
lS according to ~ection 1., 19.5 parts of a commercial,
methanol-etherified melamine resin (75% in isobutanol)
and 10 parts of butylglycol. This mixture is stirred
for a further 30 minutes using a high-speed stirrer at
1000 rpm.
3.2 Preparation of a blue-pigmented ~iqment paste
7 parts of Paliogen blue, 57 parts of the polyurethane
resin solution prepared according to section 1., 15
parts of butylglycol and 21 parts of a commercial,
methanol-etherified melamine resin (75% in isobutanol)
are mixed with stirring and dispersed in a sand mill.
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4. Preparatton of components (I) accord~ng to the
invont~on
4.1 Preparation of comPonent (I)-1
30 parts of the pigment paste prepared according to
section 3.1 are mixed thoroughly with 40 parts of the
aqueous polyurethane resin dispersion prepared
according to ~ection 2. and 30 part~ of deionized
water. The component (I) obt~; nPA in thi~ way i8
readily meterable, can be mixed very well with
component~ (I) pigmented with other colors, for example
with component (I)-2 (see below), and has an eYcellent
stability on storage.
4.2 Preparation of components ~I~-2
30 parts of the pigment paste prepared according to
~ection 3.2 are thoroughly mixed with 40 parts of the
aqueous polyurethane resin disper~ion prepared
according to section 2. and 30 parts of deionized
water. A component (I) iB obtA; ne~ which is readily
meterable, can be mixed readily with components (I)
pigmented with other colors, such as with component
(I)-1 (see above), and has a very good stability on
~torage.
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5. Preparat~on of a component (II) according to the
invention
35.5 parts of deionized water, 1.5 partff of butyl
glycol, 0.5 part of a commercial antifoam and 5 parts
of a 3.5% fftrength solution of a commercial
polyacrylate thickener in water are added with stirring
to 57.5 partff of a preswollen aqueous paste cont~;n;ng
3% by weight of an inorganic sodium-magnesium
phyllosilicate thickener and 3% by weight of
polypropylene glycol having a nu~mber-average molecular
weight of 900, the percentages being based on the
overall weight of the paste. The component (II)
prepared in this way is very readily miscible with the
components (I)-l and (I)-2 prepared according to
section 4.1 and section 4.2, and has an excellent
fftability on storage.
