Aqueous coating compositions containing water dispersible polyurethane polyureas as binders and the coatings produced therefrom

This invention relates to an aqueous coating composition containing aluminum pigments and a water dispersible polyurethane polyurea binder which contains PA0 (i) at least 200 milliequivalents per 100 g of solids of chemically incorporated carbonate groups --O--CO--O-- and PA0 (ii) a combined total of up to 320 milliequivalents per 100 g of solids of chemically incorporated urethane groups --NH--CO--O-- and chemically incorporated urea groups --NH--CO--NH--. The invention further relates to coatings prepared from the aqueous coating composition.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to new aqueous coating compositions for the 
production of metallic base lacquers wherein the binder is based on 
polyurethane polyureas containing a minimum amount of carbonate groups and 
a maximum amount of urethane and urea groups, and to the coatings produced 
from these coating compositions. 
2. Description of the Prior Art 
The coating of motor vehicles with so-called metallic coatings has in 
recent years increasingly replaced coating in plain colors. The classical 
one layer coating has therefore progressively given way to the formation 
of an intermediate build up of layers of metal pigmented base coats and 
clear top coats. 
These base coats must be highly diluted and, therefore, make a relatively 
very large contribution to the total solvent emission from a coating line. 
There has therefore been a trend to use base coats in which the binders 
are soluble or dispersible in water. Such binder solutions or dispersions 
must be suitable for use in preparing: 
the first (original) coating applied by the manufacturer in which the 
coating composition is used in stoving systems, and 
a repair coating which is applied to the vehicle after its manufacture and 
is therefore limited to the temperatures obtained during forced drying 
(i.e., .ltoreq.90.degree. C.). 
The use of aqueous binders as metallic base coats is known. For example, 
DE-OS 3,210,051 describes metallic base coats in which the binders are 
based on water dispersible polyurethane polyureas which can be crosslinked 
with melamine formaldehyde resins or blocked polyisocyanates with the aid 
of heat after the base coat has been applied. EP-A-256,540 discloses 
aqueous mixtures of polymers containing hydroxyl groups and hydrophilic 
polyurethane polyureas which are substantially identical to those just 
described and may also be cross-linked by this method. 
According to EP-A-260,447, polycondensates are used as mixtures with 
conventional polyurethane dispersions. The polycondensates contain 
carboxyl and epoxy groups, are self cross-linking and therefore do not 
require the addition of melamine resins. 
Similar to EP-A-256,540, binders for metallic multilayered coatings based 
on mixtures of hydroxyl-containing polymers and hydrophilic polyurethane 
polyureas are described in EP-A-297,576; however, the polymers for these 
binders are prepared by emulsion polymerization of their monomers in the 
aqueous polyurethane polyurea dispersion used as carrier medium. 
Polyurethane dispersions in which the dispersed phase is based on 
cross-linked polyurethanes are described in DE-OS 3,545,618 and in DE-OS 
3,606,513. In the former, cross-linking is occurs before dispersion in 
water, while in the latter the polyurethane is crosslinked by heating 
after conversion into an aqueous dispersion. 
Common to all of these known polyurethanes and polyurethane polyureas is 
the fact that the macrodiols used for their preparation are polyether 
polyols or preferably polyester diols and, in particular, polylactone 
diols. The drying and cross-linking temperatures mentioned in the prior 
publications generally range from about 80.degree. C. to 140.degree. C., 
which satisfies the condition mentioned above that the binders must be 
suitable for two different uses, i.e., as stoving lacquer binders used for 
the original coating in the manufacture of the car body (stoving 
temperatures above 140.degree. C.) and as binders for repair lacquers 
which may be used, for example, for recoating individual faulty patches on 
the already assembled vehicle and which are cured at about 80.degree. C. 
It must be possible to use the same lacquer formulation for the repair 
coating as that used for the stoving lacquer, both for economic reasons 
and to ensure absolute identity of color and surface effect. It is also 
essential that the most important coatings, e.g., adhesion and weather 
resistance, must also be obtained in the repair coatings. 
One particularly important property is the resistance of the coating to 
condensation water. This property is determined according to DIN 50,017 by 
exposing a coated test sample to condensing water vapor at about 
40.degree. C. in an air conditioning chamber. After a predetermined length 
of time, the test sample is examined for the formation of blisters which 
are an indication of the loss of adhesion between the coating and the 
substrate due to moisture penetrating the lacquer film. The brilliance (or 
"distinctness of image" (DOI)) is also determined by this test and should 
not undergo any significant deterioration. Lacquer films which have been 
cured at low temperatures in the drying process have particular difficulty 
passing this test, especially if they have been formed from aqueous 
dispersions. Thus polyurethanes from the aqueous phase which are 
commercially available generally only moderately pass this test and in 
some cases fail completely. 
Another essential requirement for the repair coating is when the metallic 
base coat is cured at low temperature, it must adhere firmly to the 
previously stoved top coat lacquer. The reason for this is that if any 
areas of coated surface on a finished part are damaged during assembly, 
the faulty patches are generally rubbed down only over a small area with a 
suitable abrasive. This either completely removes the top coat of lacquer 
or roughens it up sufficiently to enable the fresh layer of lacquer to 
adhere firmly. However, in order to ensure optical continuity the 
repairing base coat is sprayed over a wide area on and adjacent to the 
faulty patch and therefore over a considerable area of top coat lacquer 
which has not been rubbed down. The repair coating must adhere just as 
firmly to this area as to the original surface layer. The adhesion is 
determined in practice by the grid section method (according to s DIN 
151). The known polyurethane coatings do not satisfy the above requirement 
satisfactorily, if at all. 
It is an object of the present invention to provide new aqueous coating 
compositions for the production of metallic base coats which satisfy the 
previously mentioned property requirements, i.e., (1) coatings of the same 
quality are obtained regardless of the curing temperature so that the 
coating compositions are suitable for both stoving lacquers for the 
unfinished shell of motor vehicles and as repair lacquers and (2) coatings 
obtained from the compositions possess good resistance to condensation 
water and good adhesion regardless of their method of application. 
It was surprisingly found that this object could be achieved with the 
coating compositions according to the present invention. The polyurethane 
polyureas present as binders or binder components in the coating 
compositions according to the invention have a minimum carbonate group 
content and a maximum urethane and urea group content which surprisingly 
results in the in the desired property improvements. 
SUMMARY OF THE INVENTION 
This invention relates to an aqueous coating composition containing 
aluminum pigments and a water dispersible polyurethane polyurea binder 
which contains 
(i) at least 200 milliequivalents per 100 g of solids of chemically 
incorporated carbonate groups --O--CO--O-- and 
(ii) a combined total of up to 320 milliequivalents per 100 g of solids of 
chemically incorporated urethane groups --NH--CO--O-- and chemically 
incorporated urea groups --NH--CO--NH--. 
The invention further relates to coatings prepared from the aqueous coating 
composition. 
DETAILED DESCRIPTION OF THE INVENTION 
The polyurethane polyureas essential to this invention may be prepared in 
known manner by reacting 
a) organic polyisocyanates which contain no hydrophilic groups or groups 
convertible into hydrophilic groups with 
b) relatively high molecular weight organic polyhydroxyl compounds which 
have no hydrophilic groups or groups convertible into hydrophilic groups, 
c) optionally low molecular weight compositions containing at least two 
isocyanate reactive groups but no hydrophilic groups or groups capable of 
conversion into hydrophilic groups, 
d) optionally non-ionic hydrophilic starting components containing at least 
one isocyanate group or at least one isocyanate reactive group and 
e) Optionally starting components containing at least one ionic group or at 
least one group capable of conversion into an ionic group as well as at 
least one isocyanate reactive hydrogen atom, 
provided that the quantities of non-ionic groups and ionic groups present 
in components d) and e) are sufficient to ensure the dispersibility of the 
polyurethane polyureas in water. 
The reaction between isocyanate groups and hydroxyl groups results in 
urethane groups, while any urea groups present in the reaction products 
are formed from aminic starting components and/or the reaction between 
isocyanate groups and the dispersing water which is always possible during 
the preparation of the aqueous polyurethane dispersions. It is essential 
to this invention that the nature and quantitative proportions of the 
starting materials are chosen such that the resulting polyurethane 
polyureas contain at least 200 milliequivalents, preferably at least 250 
milliequivalents, per 100 of solids content, of chemically incorporated 
carbonate groups --O--CO--O--, and a combined total of up to 320 
milliequivalents, preferably 200 to 300 milliequivalents and more 
preferably 200 to 300 milliequivalents, per 100 g of solids content, of 
urethane groups --NH--CO--O-- and urea groups --NH--CO--NH--. 
The polyisocyanate component a) used for the process according to the 
invention includes any polyisocyanates known from polyurethane chemistry. 
These polyisocyanates generally have a molecular weight of 112 to 1000, 
preferably 140 to 400. Suitable polyisocyanates are those which correspond 
to the formula Q(NCO).sub.n wherein Q represents an organic group obtained 
by removing the isocyanate groups from an organic polyisocyanate having a 
molecular weight of 112 to 1000, preferably 140 to 400, and n stands for a 
number from 2 to 4, preferably 2 or 3 and more preferably 2. In the above 
formula Q preferably represents a divalent aliphatic hydrocarbon group 
having 4 to 18 carbon atoms, a divalent cycloaliphatic hydrocarbon group 
having 5 to 15 carbon atoms, a divalent aromatic hydrocarbon group having 
6 to 15 carbon atoms or an araliphatic hydrocarbon group having 7 to 15 
carbon atoms. Examples of suitable polyisocyanates include tetramethylene 
diisocyanate, 1,6-diisocyanatohexane (HDI) dodecamethylene diisocyanate, 
2,2,4-trimethylhexane diisocyanate, undecane diisocyanate-(1,11), lysine 
ester diisocyanate, cyclohexane-1,3- and -1,4-diisocyanate, 
1-isocyanato-3-isocyanatomethyl-3,5,5-trimethyl cyclohexane (IPDI), 
4,4'-diisocyanatodicyclohexylmethane and the compound corresponding to the 
formula 
##STR1## 
Also suitable are aromatic diisocyanates such as 2,4-diisocyanatotoluene 
and/or 2,6-diisocyanatotoluene, 4,4"-diisocyanatodiphenyl methane and 
1,4-diisocyanatoisopropyl benzene. HDI, IPDI and mixtures of these 
diisocyanates are particularly preferred. 
Component b) includes organic polyhydroxyl compounds having a molecular 
weight of 300 to 5000, preferably from 500 to 3000, and containing at 
least 50% by weight, preferably more than 70% by weight, of polyhydroxy 
polycarbonates. The polyhydroxy polycarbonates are esters of carbonic acid 
obtained by the reaction of carbonic acid derivatives, e.g. diphenyl 
carbonate or phosgene, with diols. Examples of these diols include 
ethylene glycol, propane-1,2- and 1,3-diol, butane-1,4- and -1,3-diol, 
hexane-1,6-diol, octane-1,8-diol, neopentyl glycol, 1,4-bis-hydroxymethyl 
cyclohexane, 2-methyl-propane-1,3diol, 2,2,4-trimethylpentane-1,3-diol, 
diethylene glycol, tri, and tetraethylene glycol, dipropylene glycol, 
polypropylene glycols, dibutylene glycol, polybutylene glycols, bisphenol 
A and tetrabromo bisphenol A. The diol component preferably contains from 
40 to 100% by weight of a hexane diol, preferably hexane-1,6-diol, and/or 
hexane diol derivatives preferably containing ether or ester groups in 
addition to terminal OH groups, e.g. the products obtained by the reaction 
of 1 mole of hexane diol with .gtoreq.1 mole, preferably 1 to 2 moles, of 
caprolactone according to DE-AS 1,770,245 or the products obtained by the 
etherification of hexane diol with itself to form dihexylene or 
trihexylene glycol according to DE-AS 1,570,540. The polyether 
polycarbonate diols described in DE-OS 3,717,060 are also very suitable. 
The hydroxyl polycarbonates should be substantially linear although they 
may, if desired, be slightly branched by the incorporation of 
polyfunctional components, in particular low molecular weight polyols such 
as glycerol, trimethylol propane, hexane-1,2,6-triol, butane-1,2,4-triol, 
trimethylol propane, pentaerythritol, quinitol, mannitol and sorbitol, 
methyl glycoside and 1,4,3,6-dianhydrohexitols. 
In addition to the polyhydroxy polycarbonates, the starting component b) 
may contain other known polyhydroxyl compounds have the previously 
described molecular weights, e.g. 
1. dihydroxy polyesters obtained from dicarboxylic acids such as succinic 
acid, adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic 
acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid and 
from diols such as ethylene glycol, propane-1,2-diol, propane-1,3-diol, 
diethylene glycol, butane-1,4-diol, hexane-1,6-diol, octane-1,8-diol, 
neopentyl glycol, 2-methyl propane-1,3-diol and the various isomeric 
bis-hydroxymethyl cyclohexanes; 
2. polylactones such as the polymers of .epsilon.-caprolactone initiated 
with the above mentioned dihydric alcohols; and 
3. polyethers, e.g., the polymers or copolymers of tetrahydrofuran, styrene 
oxide, propylene oxide, ethylene oxide, the butylene oxides or 
epichlorohydrin initiated with divalent starter molecules such as water, 
the above mentioned diols or amines containing 2 NH bonds, in particular 
the polymers and copolymers of propylene oxide and optionally ethylene 
oxide. Ethylene oxide may be used as a portion of the total quantity of 
ether molecules, provided the resulting polyether diol contains not more 
than 10% by weight of ethylene oxide units. It is preferred to use 
polyether diols which have been obtained without the addition of ethylene 
oxide, especially those based on propylene oxide and tetrahydrofuran 
alone. 
The starting components c) optionally used are known low molecular weight 
compounds which have a molecular weight below 300, contain hydroxyl and/or 
amino groups and are at least difunctional in isocyanate addition 
reactions. Compounds which are difunctional in isocyanate addition 
reactions (chain lengthening agents) compounds which are at least 
trifunctional in isocyanate addition reactions (cross-linking agents) and 
mixtures of such compounds may be used as starting components c). Examples 
of these compounds include low molecular weight polyhydric alcohols such 
as ethylene glycol, propane-1,2- and -1,3-diol, butane-1,4- and -1,3-diol, 
hexane-1,6-diol, octane-1,8-diol, neopentyl glycol, 1,4-bis-hydroxymethyl 
cyclohexane, 2-methyl-propane-1,3-diol, 2,2,4-trimethyl pentane-1,3-diol, 
glycerol, trimethylol propane, trimethylol ethane, the isomeric hexane 
triols and pentaerythritol; low molecular weight diamines such as ethylene 
diamine, 1,2- and 1,3-diaminopropane, 1,3-, 1,4- and 1,6-diaminohexane, 
1,3-diamino-2,2-dimethyl propane, isophorone diamine, 
4,4'-diaminodicyclohexyl methane, 4,4-diamino-3,3'-dimethyldicyclohexyl 
methane, 1,4-bis-(2-amino-prop-2-yl)-cyclohexane, hydrazine, hydrazide and 
mixtures of such diamines and hydrazines; higher functional polyamines 
such as diethylene triamine, triethylene tetramine, dipropylene triamine 
and tripropylene tetramine; hydrogenated products of addition of 
acrylonitrile to aliphatic or cycloaliphatic diamines, preferably those 
obtained by the addition of an acrylonitrile group to a molecule of a 
diamine, e.g. hexamethylene propylene triamine, tetramethylene propylene 
triamine, isophorone propylene triamine or 1,3- or 1,3-cyclohexane 
propylene triamine and mixtures of such polyamines. 
The hydrophilic starting components d) are compositions containing ethylene 
oxide units incorporated within polyether chains, specifically: 
d1) diisocyanates and/or compositions which contain isocyanate reactive 
hydrogen atoms and are difunctional in isocyanate polyaddition reactions, 
the diisocyanates and compositions also containing polyether side chains 
containing ethylene oxide units, and 
d2) monoisocyanates and/or compositions which are monofunctional in 
isocyanate polyaddition reactions and contain an isocyanate reactive 
hydrogen atom, the monoisocyanates and compositions also containing 
terminal polyether chains containing ethylene oxide units and 
d3) mixtures of dI) and d2). 
Compounds used as starting component dI) are preferably compounds 
corresponding to formula (I) 
##STR2## 
and/or compositions corresponding to formula (II) 
##STR3## 
The compounds d2) may in particular be compositions corresponding to 
formula (III) 
EQU HO--X--Y--R" (III) 
compounds corresponding to formula (IV) 
EQU HR'N--X--Y--R" (IV) 
and/or compositions corresponding to formula (V) 
##STR4## 
formulas (I) to (V) R represents a divalent group obtained by removing the 
isocyanate groups from a diisocyanate corresponding to the formula 
R(NCO).sub.2 as previously described (wherein R corresponds to the 
definition of Q). 
R' represents hydrogen or a monovalent hydrocarbon group having 1 to 8 
carbon atoms, preferably hydrogen or a methyl group, 
R" represents a monovalent hydrocarbon group having 1 to 12 carbon atoms, 
preferably an unsubstituted alkyl group having 1 to 4 carbon atoms, 
X represents a group obtained by removing the terminal oxygen atom from a 
polyalkylene oxide chain having 5 to 90, preferably 20 to 70 chain 
members, which chain members contain at least 40%, preferably at least 
65%, of ethylene oxide units and may in addition contain propylene oxide, 
butylene oxide or styrene oxide units, preferably propylene oxide units, 
Y represents oxygen or NR"' wherein R"' has the same definition as R" and 
Z represents a group which corresponds to the definition of Y. 
The preparation of these hydrophilic starting components (I) to IV) is 
carried out by methods analogous to those described in U.S. Pat Nos. 
3,920,598, 3,905,929, 4,190,566 and 4,237,264, the disclosures of which 
are herein incorporated by reference. 
The compounds used as starting component e) have at least one isocyanate 
reactive group and at least one, preferably one ionic group or group 
convertible into an ionic group (i.e., a o potential ionic group). They 
include the alcohols containing tertiary amino groups, hydroxy carboxylic 
acids, hydroxy sulphonic acids, amino carboxylic acids and amino sulphonic 
acids disclosed in U.S. Pat. No. 3,479,310, herein incorporated by 
reference. Instead of these starting components containing potential ionic 
groups, the corresponding salt type derivatives thereof may be used, i.e., 
ionic groups formed by the quaternization or neutralization of the 
potential ionic groups. Examples of suitable quaternizing and neutralizing 
agents for converting the potential ionic groups into ionic groups are 
also set forth U.S. Pat. No. 3,479,310, which has previously been 
incorporated by reference. When potential ionic starting components are 
used, the at least partial conversion of the potential ionic groups into 
ionic groups is carried out by quaternization or neutralization after or 
during preparation of the polyurethane polyureas. 
Preferred starting components e) include 2,2-bis-(hydroxy-methyl)-alkane 
monocarboxylic acids having a total of 5 to 8 carbon atoms, i.e., 
compositions corresponding to the formula: 
##STR5## 
wherein R represents an alkyl group having 1 to 4 carbon atoms, and/or 
salts thereof obtained by partial or complete neutralization with organic 
amines or NH3. 2,2-dimethylol propionic acid (2,2-bis-hydroxymethyl 
propionic acid) and/or salts thereof are particularly preferred for use as 
starting component e). 
Preparation of the polyurethanes from the starting components a) to e) is 
carried out in known manner in one or more stages using the reactants in 
such proportions that the equivalent ratio of isocyanate groups present in 
the starting o components to isocyanate reactive groups present in the 
starting components is 0.8:1 to 2:1, preferably 0.95:1 to 1.5:1 and more 
preferably 0.95:1 to 1.2:1. 
Component d) is used in a quantity such that the polyurethane polyurea 
contains 0 to 30% by weight, preferably from I to 20% by weight, of 
ethylene oxide units incorporated in terminal or lateral polyether chains. 
The quantity of component e) and the degree of neutralization to form ionic 
groups are calculated to ensure that the polyurethane finally obtained 
contains 0 to 120, preferably 1 to 80 milliequivalents, of ionic groups 
per 100 g of solids. The total quantity of ethylene oxide units and ionic 
groups must be sufficient to ensure the dispersibility of the polyurethane 
polyureas in water. 
The reaction of the starting components a) to e) may be carried out in one 
or more stages, optionally in the presence of an isocyanate-inert, water 
miscible solvent so that the reaction products are obtained in the form of 
a solution in such a solvent. In this context, the term "solution" denotes 
either a true solution or a water in oil emulsion which may be formed if, 
for example, individual starting components are used in the form of 
aqueous solutions. Examples of suitable solvents include acetone, 
methylethyl ketone, N-methyl pyrrolidone and any mixtures of such 
solvents. These solvents are generally used in such quantities that the 
reaction products of starting components a) to e) are obtained in the form 
of 10 to 70% by weight solutions. 
When the preparation of polyurethane polyureas is carried out as a single 
stage reaction, the starting components containing isocyanate reactive 
groups are preferably mixed together and then reacted with the starting 
components containing isocyanate groups. This reaction is preferably o 
initially carried out in the absence of solvents at temperatures of 
50.degree. to 150.degree. C., optionally in the presence of known 
catalysts, and the nature and quantitative proportions of the starting 
components are preferably chosen to provide an equivalent ratio of 
isocyanate groups to isocyanate reactive groups of from 0.8:1 to 1.05:1. 
The viscosity of the mixture increases during the course of the reaction 
and one of the above mentioned solvents is therefore gradually added to 
the mixture. The polyurethane content of the organic solution finally 
obtained is adjusted to a concentration of 10 to 70% by weight, in 
particular 15 to 55% by weight. 
When a two stage process is employed, an isocyanate prepolymer is 
preferably first prepared solvent free at about 50.degree. to 150.degree. 
C. from excess quantities of isocyanate-containing starting components and 
hydroxyl-containing starting components at an NCO/OH equivalent ratio of 
1.1:1 to 3.5:1, preferably 1.2:1 to 2.5:1, with or without a solvent, and 
this isocyanate prepolymer is then taken up in a solvent if no solvent has 
been used up to this stage. The solution obtained is then further reacted 
with chain lengthening or cross-linking agents c) which are optionally 
used in the form of aqueous solutions and are preferably starting 
components of the above mentioned type containing primary and/or secondary 
amino groups. The quantity of starting components c) used in the second 
stage is calculated to ensure that the equivalent ratio of all the 
starting components used in the first and second stage conforms to the 
conditions previously stated. 
The end products of both variations (single stage or two stage) are 
solutions of the reaction products in the above mentioned solvent having a 
solids content within the ranges indicated above. 
If any potential ionic groups are present, their at least partial 
conversion into ionic groups by quaternization or neutralization is 
advantageously carried out before the addition of the dispersing water. If 
starting component e) contains carboxyl groups, which is preferred, in 
particular dimethylol propionic acid, the neutralizing agents used are 
preferably tertiary amines such as triethylamine, tri-n-butylamine, 
N,N,N-trimethyl cyclohexylamine, N-methyl morpholine, N-methyl piperazine, 
N,N-dimethyl ethanolamine, N-methyl piperidine and triethanolamine. For 
the neutralization of carboxyl groups, it is also preferred to use ammonia 
under the conditions set forth in EP-A-269 972. 
After the addition of water as solvent or dispersing medium, at least the 
major proportion of the auxiliary solvent used is optionally removed by 
distillation. The water is used in a quantity which is sufficient to 
provide a product with a solids content of 10 to 60% by weight, preferably 
20 to 45% by weight. 
The polyurethane polyureas may also be prepared by other methods known in 
the art, for example by using hydrazine or diamines as chain lengthening 
agents c) in a blocked form, i.e , in the form of the corresponding azines 
or ketimines as disclosed in U.S. Pat. Nos. 4,269,748 and 4,829,122, both 
of which are herein incorporated by reference. 
The so called prepolymer mixing process may also be used (see D. Dieterich, 
Angew. Makromol. Chem. 9A, 142 (1981)). In this process, an NCO prepolymer 
is initially prepared as described above and after at least partial 
conversion of any potential ionic groups present into ionic groups, the 
prepolymer is mixed with water to form an emulsion. The NCO groups of the 
prepolymer are then brought to reacted in the aqueous phase by the 
addition of aminic chain lengthening or cross-linking agents c) and/or by 
a reaction with water. 
In the coating compositions according to the invention, the polyurethane 
polyureas prepared as described above and dispersed in water are present 
as binders either on their own or in admixture with other binders. When 
such mixtures of different binder components are used, the proportion of 
the polyurethane polyureas according to the present invention is at least 
60% by weight, based on the total weight of the binders used. Other 
binders optionally used in addition to the polyurethane polyureas 
according to the invention include commercial, aqueous polyacrylate 
dispersions or solutions, polyester dispersions or solutions and/or water 
dilutable polyester resins. 
The coating compositions according to the invention contain aluminum 
pigments, which are known, in addition to water, the previously described 
binders and optionally other color pigments. Further, the coating 
compositions according to the invention may contain conventional 
cross-linking agents as well as other auxiliary agents and additives 
conventionally used in lacquer technology. 
Examples of suitable aluminum pigments include preparations (aluminum 
pastes) of the type available commercially and especially used for aqueous 
metallic base lacquers, e.g., those marketed under the trade names Alpate 
WX (Toyo Aluminum K.K.) and Stapa Hydrolac (Eckart-Werke). 
Other color pigments may optionally be used and include any inorganic or 
organic pigments known for the formulation of colored metal effect coating 
compositions. 
The cross-linking agents optionally used include known, partially or 
completely esterified water miscible melamineformaldehyde condensation 
products or known blocked polyisocyanates. 
These cross-linking resins may be present in the coating compositions in 
quantities which are sufficient to provide a solids contents of up to 50% 
by weight, preferably up to 30% by weight, based on the solids content of 
the binder free from cross-linking agents. 
Other auxiliary agents and additives which may optionally be used include, 
e.g., commercial organic and inorganic thickeners (such as carboxyl 
group-containing polyacrylates, polyurethanes or special layer silicates), 
suitable wetting agents and defoamants. These auxiliary agents and 
additives may be added before or after the process of dispersion. 
The coating compositions according to the invention have a solids content 
of 10 to 40% by weight, preferably 15 to 25% by weight. The dispersed 
binders according to the invention which PG,18 are present in the coating 
compositions are in the form of dispersed particles having average 
particle diameters of about 10 to 1000 nm, preferably from 30 to 500 nm. 
The coating compositions according to the invention are eminently suitable 
for the formation of metallic base layers in multilayered coatings. The 
top coats used may be any solvent-containing or aqueous clear lacquers 
such as commercial two-component polyurethane coating compositions or heat 
hardenable one-component coating compositions based on polyacrylates 
and/or polyesters and melamine resins. The coating compositions according 
to the invention may be used for coating any substrates, e.g., metals, 
plastics, wood, glass and ceramic materials. The coating compositions 
according to the invention are particularly suitable for producing metal 
effect coatings on the materials normally used for the manufacture of car 
bodies or parts such as plastics or steel sheets optionally previously 
treated with a primer.

In the following examples, all parts and percentages are based on weight 
unless otherwise indicated. 
EXAMPLES 
The following dispersions are used in the examples: 
Polyurethane polyurea dispersion A (according to the invention) 
A prepolymer containing about 5% of free isocyanate groups was prepared by 
reacting 850 parts of a polycarbonate of hexane-1,6-diol (prepared by the 
reaction of hexane-1,6-diol and diphenyl carbonate; hydroxyl number: 56; 
molecular weight: about 2000), 67.5 parts of a monofunctional polyether 
alcohol (OH number 26; prepared by the alkoxylation of n-butanol using a 
mixture of 83% ethylene oxide and 17% propylene oxide), 40.2 parts of 
2,2'-bis-hydroxymethyl propionic acid (DMPA) and 23.4 parts of 
butane-1,4-diol at 100.degree. C. with a mixture of 151.2 parts of 
1,6-diisocyanatohexane (HDI) and 199.8 parts of 
3-isoyanatomethyl-3,5,5-trimethyl cyclohexyl isocyanate (IPDI). The 
prepolymer was dissolved in 2440 parts of acetone and the solution was 
cooled to 50.degree. C. 
A solution in 500 parts of water was prepared from 19.8 parts of ethylene 
diamine and 7.5 parts of hydrazine hydrate. This solution was slowly added 
to the prepolymer solution with vigorous stirring. A thin, whitish cloudy 
solution was obtained. 17.8 parts of N,N-dimethyl ethanolamine were added. 
1525 parts of deionized water were then added with vigorous stirring and 
an opaque, bluish white dispersion of the solid substance was obtained. 
The acetone was removed from this dispersion by distillation under vacuum. 
A pure, aqueous dispersion having a solids content of 40% was left behind. 
The solids content of the dispersion contained (meq%=meq per 100 g of 
solids): 
409 meq% of carbonate groups (--O--CO--O--) 
147 meq% of urethane groups (--NH--CO--O--) 
94 meq% of urea groups (--NH--CO--NH--) 
241 meq% of urethane and urea groups. 
Polyurethane polyurea dispersion B (according to the invention) 
An aqueous dispersion was obtained from the following materials by the 
method used to prepare dispersion A: 
540 parts of the hydroxyl polycarbonate used to prepare dispersion A 
45 parts of the polyether started on n-butanol used to prepare dispersion A 
40.2 parts of DMPA 
37.8 parts of butane-1,4-diol 
151.2 parts of HDI 
199.8 parts of IPDI 
7.5 parts of hydrazine hydrate 
19.8 parts of ethylene diamine 
17.8 parts of N,N-dimethyl ethanolamine. 
The dispersion contained 35% of solids and had the following composition: 
339 meq% of carbonate groups (--O--CO--O--) 
192 meq% of urethane groups (--NH--CO--O--) 
123 meq% of urea groups (--NH--CO--NH--) 
315 meq% of urethane and urea groups. 
Polyurethane polyurea dispersion C (according to the invention) 
An aqueous dispersion was prepared from the following materials by the 
method used to prepare dispersion A: 
850 parts of the hydroxyl polycarbonate used to prepare dispersion A 
67.5 parts of the polyether started on n-butanol used to prepare dispersion 
A 
21.4 parts of DMPA 
22.5 parts of butane-1,4-diol 
13.4 parts of trimethylol propane 
151.2 parts of HDI 
199.8 parts of IPDI 
7.5 parts of hydrazine hydrate 
19.8 parts of ethylene diamine and 
13.4 parts of N,N-dimethyl ethanolamine. 
The dispersion contained 35% of solid substance which has the following 
composition: 
410 meq% of carbonate groups (--O--CO--O--) 
148 meq% of urethane groups (--NH--CO--O--) 
95 meq% of urea groups (--NH--CO--NH--) 
243 meq% of urethane and urea groups. 
Polyurethane polyurea dispersion (according to the invention) 
The procedure was the same as that used to prepare dispersion A except that 
the polycarbonate diol was replaced by a polycarbonate polyester diol 
having an OH number of 56 and prepared according to DE-AS 1 770 245 by the 
reaction of diphenyl carbonate with the reaction product of 1 mole of 
hexane diol and 1 mole of .epsilon.-caprolactone. The resulting dispersion 
had a solids content of 39.5%. 
The solid substance contained: 
214 meq% of carbonate groups (--O--CO--O--) 
147 meq% of urethane groups (--NH--CO--O--) 
94 meq% of urea groups (--NH--CO--NH--) 
241 meq% of urethane and urea groups. 
Polyurethane polyurea dispersion E (according to the invention) 
The procedure was the same as for dispersion A except that only 425 g of 
the polycarbonate diol was used. The remaining 425 parts was based on a 
polyester diol having an OH number of 56 and prepared from adipic acid and 
a mixture of hexane diol and neopentyl glycol (molar ratio 65:35). The 
dispersion obtained has a solids content of 40.5%. 
The solid substance contained: 
204 meq% of carbonate groups (--O--CO--O--) 
147 meq% of urethane groups (--O--CO--NH--) 
94 meq% of urea groups (--NH--CO--NH--) 
241 meq% of urethane and urea groups. 
Polyurethane polyurea dispersion F (comparison example) 
An aqueous dispersion was prepared from the following materials by the 
method used to prepare dispersion A: 
380 parts of the hydroxyl polycarbonate used to prepare dispersion A 
45 parts of the polymer started on a n-butanol used to prepare dispersion A 
53.6 parts of DMPA 
184.8 parts of HDI 
244.2 parts of IPDI 
63 parts of butane-1,4-diol 
42 parts of ethylene diamine 
5.0 parts of hydrazine hydrate 
17.8 parts of N,N-dimethyl ethanolamine. 
The dispersion obtained has a solids content of 38.9%. The solid substance 
contained: 
244 meq% of carbonate groups (--O--CO--O--) 
255 meq% of urethane groups (--NH--CO--O--) 
167 meq% of urea groups (--NH--CO--NH--) 
422 meq% of urethane and urea groups. 
Polyurethane polyurea dispersion G (comparison example) 
An aqueous dispersion was prepared from the following materials by the 
method used to prepare dispersion A: 
153 parts of a polyester having an OH number of 66 and prepared from adipic 
acid and a mixture of hexane diol and neopentyl glycol (molar ratio 65:35) 
231 parts of a hexane diol polyadipate having an OH number of 134 
45 parts of the polyether started on n-butanol used to prepare dispersion A 
53.6 parts of DMPA 
488.4 parts of IPDI 
13.4 parts of TMP 
33.8 parts of butane-1,4-diol 
42 parts of ethylene diamine 
7 parts of hydrazine hydrate 
13.8 parts of N,N-dimethyl diethanolamine. 
The dispersion had a solids content of 39.6%. 
The solid substance was free from carbonate groups and contained: 
244 meq% of urethane groups (--NH--CO--O--) 
163 meq% of urea groups (--NH--CO--NH--) 
407 meq% of urethane and urea groups. 
Polyurethane polyurea dispersion H (comparison example) 
An aqueous dispersion was prepared from the following materials by the 
method used to prepare dispersion A: 
850 parts of a polyester having an OH number of 56 and prepared from adipic 
acid and a mixture of hexane diol and neopentyl glycol (molar ratio 65:35) 
67.5 parts of the polyether started on n-butanol used to prepare dispersion 
A 
402 parts of DMPA 
151.2 parts of HDI 
199.8 parts of IPDI 
23.4 parts of butane-1,4-diol 
19.8 parts of ethylene diamine 
7.5 parts of hydrazine hydrate and 
17.8 parts of N,N-dimethyl diethanolamine. 
The dispersion had a solids content of 40.2%. 
The solid substance was free from carbonate groups and contained: 
147 meq% of urethane groups (--NH--CO--O--) 
94 meq% of urea groups (--NH--CO--NH--) 
241 meq% of urethane and urea groups. 
Polyurethane polyurea dispersion I (comparison example based on DE-OS 32 10 
051) 
Using the method of preparation and ingredients set forth for "polyurethane 
dispersion 1" in DE-OS 32 10 051, a 35% dispersion was prepared. The solid 
substance was free from carbonate groups and contained: 
208 meq% of urethane groups (--NH--Co--O--) 
62 meq% of urea groups (--NH--CO--NH--) 
270 meq% of urethane and urea groups. 
Polyurethane polyurea dispersion K (comparison example based on DE-OS 32 10 
051) 
Using the method of preparation and ingredients set forth for "polyurethane 
dispersion 5" in DE-OS 32 10 051 a 19% dispersion was prepared. The solid 
substance was free from carbonate groups and contained: 
63 meq% of urethane groups (--O--CO--NH--) 
97 meq% of urea groups (--NH--CO--NH--) 
360 meq% of urethane and urea groups. 
Dispersion L (according to the invention) 
1000 parts of polyurethane polyurea dispersion A (solids content: 40%) were 
mixed with 460 parts of a commercial aqueous polyacrylate dispersion 
(Joncryl 538, available from S. C. Johnson & Son Inc.) having a solids 
content of 45%. 
EXAMPLES 1 TO 11 
Aqueous metallic base lacquers ready for spraying were prepared from 
dispersions A to L. The coating compositions were based on the following 
components: 
32.31 parts* of dispersions A to L 
42.96 parts* of water 
8.77 parts of butyl glycol 
3.33 parts of N,N-dimethyl ethanolamine, 10% in water 
3.02 parts of thickener (Viscalex HV 30, available from Allied Colloids 
GmbH, Hamburg) 
4.04 parts of cross-linking agent (Cymel 325, 80% as supplied in 
isobutanol, available from Dyno-Cyanamide, Dusseldorf) 
5.57 parts of aluminum paste (Alpate WX 7160, 58%, available from Toyo 
Aluminium K.K.) 
FNT * Applies to dispersions having a solids content of about 40%. For lower 
solids contents, the quantities of dispersion and water were corrected 
accordingly so that the coating compositions ready for use have a solids 
content of 17%. 
The preparations ready for spraying have solids contents of about 17% and 
spraying viscosities of about 30 sec (DIN cup, 4 mm nozzle, 23.degree. 
C.). 
The following coatings were intended to simulate the conditions for repair 
coating on a coating line of the motor car industry. The coating 
compositions were applied to zinc phosphatized car body panels which had 
previously been coated with an electrodeposition primer and filler. 
Coating process, type I 
application of the metallic base coating compositions of Examples 1 to 11 
by spraying 
3 minutes predrying at 80.degree. C. 
application of a conventional, two-component, polyurethane, clear top coat* 
by spraying 
7 minutes exposure to air at RT 
45 minutes drying at 80.degree. C. 
Coating process, type II 
application of the metallic base coating compositions of Examples 1 to 11 
by spraying, followed by 20 minutes stoving at 140.degree. C. 
application of the metallic base coating compositions of Examples 1 to 11 
by spraying onto the hardened coatings which had not been sanded down. 
3 minutes predrying at 80.degree. C. 
application of a conventional, two-component, polyurethane, clear top coat* 
by spraying 
7 minutes exposure to air at RT 
45 minutes drying at 80.degree. C. 
FNT * The clear top coat is based on a polyacrylate polyol having an OH content 
of 4.3% (based on the solid resin) and an isocyanurate polyisocyanate 
based on hexamethylene diisocyanate and having an NCO content of 22% 
(based on the solid resin). The NCO/OH equivalent ratio was 1.0. 
The properties of the individual lacquers are set forth in the following 
table: 
__________________________________________________________________________ 
Example 
1 2 3 4 5 6 7 8 9 10 11 
Dispersion used 
A B C D E F G H I K L 
__________________________________________________________________________ 
Coating process, type I 
ME Value (flop).sup.1) 
357 
295 
331 
312 
290 
394 
336 
214 
286 
295 
220 
Brilliance (D.O.I.).sup.2) 
70 70 70 70 70 70 70 70 70 70 70 
Resistance to water of 
condensation.sup.3) 
Brilliance (D.O.I.).sup.2) 
70 65 70 70 65 40 10 60 60 40 65 
Assessment of film 
.rarw.nothing abnormal.fwdarw. 
.rarw.wrinkled.fwdarw. 
nothing 
abnormal 
Coating process, type II 
Gt 0 
Gt 0 
Gt 0 
Gt 0 
Gt 0 
Gt 5 
Gt 5 
Gt 3 
Gt 4 
Gt 5 
Gt 0 
adherence.sup.4) 
__________________________________________________________________________ 
.sup.1) Metallic effect value, determined with a Gonio Photometer GP 3 of 
Zeiss 
.sup.2) Distinction of image (100 = highly brilliant, 0 = completely mat) 
.sup.3) After 240 hours test in Atmosphere according to DIN 50,017 
.sup.4) Grid section test according to DIN 53,151 (Gt 0-5) 
Although the invention has been described in detail in the foregoing for 
the purpose of illustration, it is to be understood that such detail is 
solely for that purpose and that variations can be made therein by those 
skilled in the art s without departing from the spirit and scope of the 
invention except as it may be limited by the claims.