Note: Descriptions are shown in the official language in which they were submitted.
2 0 ~
Mo3923-us
LeA ~9,157
AN AQUEOUS COATING COMPOSITION AND
ITS USE FOR COATING SU8STRATES
BACKGROUND ~F THE INVENTION
Field of the Invention
The present invention relates to a new aqueous coating
composition containing polyacrylate resins which have
carboxylic and/or sulphonic acid functionality and are
dissolved and/or dispersed in water as an essential binder
component and (cyclo)aliphatic epoxy resins as curing agents,
and the use of the coating compositions for the production of
coatings.
Description of the Prior Art
Today aqueous coating compositions are gaining increasing
importance for ecological and economic reasons. The
replacement of coating compositions conventionally dissolved in
organic solvents is, however, technically difficult for various
reasons.
Aqueous binders based on alkyd resins and polyesters have
a marked tendency to saponification. The saponification causes
a reduction of molecular weight, which leads to a loss of
quality of the binder and the coatings obta1ned therefrom. In
addition, the storability of such binders is considerably
reduced.
Frequently, therefore, binders dissolved in purely organic
solvents are produced or sold, and are then diluted further
with water for application. During application these systems
release, in addition to water, the organic solvents contained
in the system. The ability to dilute these anionic binders
with water is obtained only by neutralization with bases,
usually organic amines. During curing, these amines are also
released. As a rule, complicated incinerators are then
necessary industrially in order to remove the organic
constituents from the waste air, while in do-it-yourself
35376TWR2g 1 9
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applications, these constituents are emitted into the ambient
air.
Another problem of these water-based coating compositions
is the distinctive viscosity anomaly. On dilution of the
aqueous lacquer solutions, the viscosity initially increases
and then decreases rapidly after passing a maximum. Because
the coating compositions react to small water additions with
considerable viscosity changes, they require particularly
careful handling.
A further disadvantage, in particular for stoving systems
containing polyester or alkyd resins in combination with
melamine resins as crosslinkers, is the relatively high curing
temperature, which is usually at least 120C. This requires a
high expenditure of energy for curing the system. For many
applications, such as the repair coating of automobiles, curing
is not possible under such temperature conditions. As a rule,
coating compositions are required that are curable at the
lowest possible temperatures and yet have suffic;ent water- and
solvent-resistance after curing. Ideal binders would be
usable, e.g., in the automobile field, both at temperatures
below 100C for repair coating and at higher temperature for
original equipment manufacture (OEM).
Other crosslinking mechanisms, such as the crosslinking of
OH-functional polymers with polyisocyanates, have some
advantages when compared to crosslinking with melamine resins.
Thus, the curing can be carried out at room temperature or,
accelerated, at 80 to 120-C. The coatings obtained in this way
possess a good mechanical property profile and are generally
resistant to gasoline and water. However, there are problems
when it is intended to apply this crosslinking principle to
aqueous formulations, since the isocyanates are reactive with
water. It was previously common to apply such systems in
purely organic solution resulting in the disadvantages
mentioned with regard to the emission of organic solvents.
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Only recently have special aqueous coating compositions
become known (e.g. DE-OS 3,8291587) to overcome these problems.
These compositions contain combinations of polyhydroxy
compounds and polyisocyanates with free isocyanate groups as
binders which are dissolved and/or dispersed in water. Yet the
difficulty remains that the side reactions of NCO groups with
water can interfere with the actual cross-linking reaction,
e.g., when detailed instructions about the composition of the
lacquer recipe and the curing conditions are not followed.
B;nders based on a polymer containing amino or ammonium
groups and epoxides also have a high reactivity and can be
cured at temperatures below 100C. However, the basic groups
needed for compatibility with water render the crosslinked
coatings highly hydrophilic, which has a negative effect on
their water resistance.
Accordingly, it is an obiect of the present invention to
provide a new coating composition which may be applied an
aqueous phase substantially free of co-solvent, is dilutable
without the viscosity anomaly, can be cured over a wide
temperature range (in particular at only moderately elevated
temperatures or room temperature), has a long processing time
and possesses good water resistance water resistance.
These objects may be achieved with the preparation of the
coating compositions according to the invention which are
described in more detail below.
SUMMARY OF THE INVENTION
The present invention relates to aqueous coating
compositions containing an aqueous solution and/or dispersion
of
a) a polyacrylate component which contains at least one
copolymer having carboxylic and/or sulphonic acid groups
which may be at least partially present in salt form, is
based on the reaction product of oleflnically unsaturated
monomers and has an acid number of 30 to 240 mg KOH/g, a
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hydroxyl number of 0 to 180 mg KOH/g, and a molecular
weight (Mn) of 500 to SO,OOO,
b) an epoxide component which contains
bl) at least one aliphatic or cycloaliphatic epoxy resin
having an average of at least 2 epoxide groups per
molecule and containing 0.2 to 2.0 equivalents of
epoxide per 100 g of resin and
b2) up to 20 wt.%, based on the weight of bl), of at
least one aliphatic monoepoxide with 7 to 25 carbon
atoms,
c) up to 10 wt.%, based on the total weight of components a)
to e), of one or more organic, water-miscible solvents,
d) up to 5 wt.%, based on the total weight of components a)
to e), of one or more external emulsifiers and
e) optionally other known coatings additiv~s,
wherein the equivalent ratio of unneutralized acid groups of
component a) to epoxide groups of component b) is 1:0.5 to 1:3.
The present invention also relates to the use of these
coating compositions for the production of coatings for curing
at 5 to 140C on any desired substrates.
DETAILED DESCRIPTION OF THE INVENTION
Component a) is selected from copolymers having carboxylic
or sulphonic acid groups, acid numbers of about 30 to 240 mg
KOH/g and hydroxyl nUmbersof o to about 180 mg KOH/g. The acid
number includes both free, i.e., unneutralized, acid groups,
particularly carboxyl groups, and also neutralized acid groups,
in particular carboxylate groups. Preferably, 0 to 30 wt.% of
the ac~d groups are present in neutralized form. In
particular, ammonia or aliphatic amines are used as
neutralizing agents, particularly those having a molecular
weight of 31 to 200. Examples include methylamine, dimethyl-
amine, trimethylamine, triethylamine, ethanolamine, 2-amino-
2-methyl-1-propanol and N,N-dimethylethanolamine. The
copolymers generally have a molecular weight (Mn~ determined by
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gel permeation chromatography using polystyrene as standard) of
500 to 50,000, preferably 1,000 to 25,000.
Preferred copolymers for use as component a) are those
prepared from
al) 0 to 70, preferably 0 to 50, wt.% styrene,
a2) 0 to 70, preferably 0 to 50, wt.% methyl methacrylate,
a3) 0 to 70, preferably 0 to 50, wt.% of an acrylate component
selected from one or more Cl to C8-alkyl acrylates,
a4) 0 to 30, preferably 0, wt.% of at least one component
lo having hydroxyl groups selected from hydroxyalkyl
(meth)acrylatès having 1 to 4 carbon atoms in the
hydroxyalkyl group,
a5) 5 to 40, preferably 10 to 30, wt.% of an acid component,
selected from acrylic acid, methacrylic acid and
v;nylsulphonic acid, preferably methacrylic acid,
a6) 0 to 30, preferably 0, wt.% of other ethylenically
unsaturated monomers,
provided that the sum of the percentages of components al) to
a6) is 100 and 0 to 30 mol% of the incorporated acid groups are
neutralized with aliphatic amines or ammonia.
Suitable monomers a3) include methyl acrylate, ethyl
acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl
acrylate, n-hexyl acrylate, n-octyl acrylate and 2-ethylhexyl
acrylate. Preferred monomers a3) are n-butyl acrylate, n-hexyl
acrylate and 2-ethylhexyl acrylate; n-butyl and/or n-hexyl
acrylate are especially preferred.
Suitable hydroxy-functional (meth)acrylates a4) include
hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate,
3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate
and mixtures of these monomers. Preferred are 2-hydroxyethyl
methacrylate and the technical mixture of 2- and 3-hydroxy-
propyl methacrylate.
Acid-containing monomer a5) is most preferably present in
an amount of 15 to 25% by weight. Methacrylic acid is
especially preferred as monomer a5).
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Suitable monomers a6), which may optionally be present,
include sub~tituted styrene derivatives such as the isomeric
vinyltoluenes, ~-methylstyrene, propenylbenzene, C5-CI2-
cycloalkyl (meth)acrylates, vinyl esters (such as vinyl
acetate, propionate or versatate) and N-methoxymethyl
(methJacrylamide.
The ability to emulsify copolymers a) depends above all
on the concentration of an incorporated anionic group and on
the presence or absence of external emulsifiers. Preferably,
the hydrophilicity of component a) is adjusted via the
incorporation of acid groups, their degree of neutralization
and/or the concomitant use of external emulsifiers d), such
that at least 20 wt.%, preferably at least 80 wt.%, of
component a) is present in a form emulsified in water; the
remainder is present in water-dissolved form. Especially
preferred agueous copolymers a) are those which have been
produced by emulsion polymerization in the aqueous medium and
consequently are present essentially in a form emulsified in
water.
Methods of production of such aqueous emulsions are known.
Extensive descriptions can be found, e.g., in Houben-Weyl,
Methoden der organischen Chemie, volume E20, Makromolekulare
Stoffe I, 4th Edition, 1987, p. 218 ff., Georg Thieme Verlag.
Epoxy resins suitable as component b) include
low-molecular (cyclo)aliphatic compounds bl) that have good
solubility or emulsifiability in water, 1f necessary in the
presence of emulsifiers d). These compounds have an average of
at least 2, preferably 2 to 5, epoxide groups per molecule and
a viscosity at 25C of 50 to lO,000 mPa.s. They also contain
0.2 to 2.0 epoxide groups per 100 9 of resin solids. A very
suitable example of such epoxy resin is "Glycidether 100", a
commercial product of the Raschig AG company. Glycidether 100
is an epoxide mixture based on a glycidyl glycerol ether, with
an epoxide value of 0.67 to 0.70 equivalents of epoxide/100 9
and a viscosity at 25C of 140 to 175 mPa.s. It also has good
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compatibility with water. Another commercial product suitable
as component bl) is Epikote 877 of the Shell Company.
Component b) can optionally contain aliphatic monoepoxides
b2) as reactive diluents in amounts of up to 20 wt.%, based on
the weight of component bl). Suitable components b2) include
glycidyl ethers of aliphatic C4-C22 alcohols, such as butyl
glycidyl ether; and epoxidized olefins, such as epoxidized
~-olefins, for example reactive diluent Edenol 817 RV of the
Henkel company.
In the coating compositions according to the invention,
components a) and b) are present in an amount such that the
molar ratio of unneutralized acid groups of component a) to
epoxide groups of component b) is 1:3 to 1:0.5, preferably
1:1.5 to 1:0.75.
The coating compositions according to the invention may
also contain up to 10 wt.%, based on the weight of components
a) to e), of water-miscible organic solvents c). Examples of
these solvents include butoxyethanol, methoxypropanol, ethanol
and acetone.
In the coating compositions according to the invention,
external emulsifiers d) may be present to assist the
emulsifiability of components a) and b). These external
emulsifiers, if used at all, are used in amounts of up to 5
wt.%, based on the total weight of components a) to e).
Suitable external emulsifiers include 3-benzyl-4-hydroxy-
biphenyl polyglycol ether and the sodium salt of di-sec.-butyl
naphthalenesulphonic acid.
The coating compositions may also contain additives d)
which are known from coatings technology. Examples include
3~ pigments, antifoaming agents, levell;ng agents, dispersion aids
for p;gment distribution, fillers, catalysts for the epoxide
addition reaction or also other non-water miscible
(hydrophobic) auxiliary solvents, which are different from
component c), but which are emulsifiable in the total system
due to the presence of the emulsifiers.
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To prepare the coating compositions it is possible to
emulsify or dissolve the epoxide component b) in the aqueous or
aqueous-organic emulsion of component a) (that may contain
hydrophilic solvents c), the previously mentioned hydrophobic
solvents and/or emulsifiers d)). The good water compatibility
of the component b), at least in presence of the emulsifiers
d), ensures good mixing by simply stirr;ng at room temperature.
If additives are to be present, they are preferably added
to the system preferably before the addition of component b).
The coating compositions according to the invention in
general have a water content of 20 to 75 wt.% and a total
content of hydrophilic solvents c) and other possible volatile
solvents, that can be part of component e), of no more than 10
wt.%, wherein these percentages are based on the total weight
f the coatiny composition.
The coating compositions according to the invention have a
processing time at room temperature of at least 10 h, often of
more than 24 h.
The coating compositions according to the invention can be
applied to suitable substrates by known methods, for example,
by spray;ng, dipping and brushing. The curing of the coatings
can be carried out within a wide temperature range of 5 to
160C, preferably 5 to 140C. Preferably the curing takes
place at room or ambient temperature. At elevated curing
temperatures, for example 80 to 140-C, stoving times of 15 to
45 minutes are usually sufficient. Irrespective of the curing
temperature, coatings are obtained which possess scratch
resistance, water resistance, solvent resistance and high
gloss.
The coating compositions according to the inventlon are
also distinguished by the lack of a the previously discussed
viscosity anomaly, i.e., on dilution with water no initial rise
in viscosity occurs.
The coating compositions according to the invention are
suitable in particular for the production of primary coats or
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top coats on any desired substrates, but particularly on
concrete, wood, metal and plastics. The coating compositions
are suitable for the production of fillers, base coats and
clear coats for both original equipment manufacture and for the
repair coating of motor vehicles. They are also suitable for
furniture coating, industrial coatings and for building
protection.
In the following examples all parts and percentages are by
weight unless otherwise indicated.
lo EXAMPLES
In the examples the following epoxy resins bl) and
polyacrylate resins a) were used.
Glvcidvl ether A
An epoxide mixture containing glycidyl glycerol ether,
flash point 118 to 135DC (Abel-Penski), Hazen color no more
than 200, epoxide value about 0.68 equivalents of epoxide/100
9, viscosity (25C) about 155 mPa.s ~commercial product of the
Raschig company, Ludwigshafen, trade name: Glycidether 100).
GlvcidYl ether B
Low-viscosity, aliphatie diepoxide, viscosity 40 to
90 mPa.s. Epoxide value: about 0.308 equivalents of
epoxide/100 9 (commercial product of the Shell company, trade
name: Epikote 877).
Polvacrvlate Example 1
In a stirred apparatus equipped with reflux condenser,
internal thermometer and dropping funnel, while 3 liters of
N2/h were passed over, 554.4 parts of distilled water, 3.9
parts of emulsifier 1 (3-benzyl-4-hydroxybiphenyl polyglycol
ether) and 0.75 parts of emulsifier 2 (di-sec.-butyl
naphthalene sulphonate) were charged and heated to 80-C with
intensive stirring. Then at 80C a solution of 1.25 parts of
ammonium peroxodisulphate and 11.25 parts of water was added
and the mixture was stirred for exactly 5 minutes. 10 vol% of
a monomer mixture containing 72.7 parts of styrene, 134.8 parts
of methyl methacrylate, 78.5 parts of n-butyl acrylate, 85.7
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parts of methacrylic acid and 7.4 parts of dodecyl mercaptan,
were added at 80C at the same time. After 15 minutes stirring
at 80C, the remainder of the monomer mixture was added
dropwise over a period of 2 hours.
After the addition was complete, a solution of 0.25 parts
of ammon;um peroxodisulphate in 12.25 parts of water was added
dropwise ;n 10 minutes and the mixture was stirred for a
further 2 hours at 80'C. The emulsion obtained had a polymer
content of 40.3 wt.%. The acid number of the polymer was 115.1
~o mg KOH/g. By dropwise addition of a 20% solution of
N,N-dimethylethanolamine in butoxyethanol, the solution was 15%
neutralized, based on the indicated acid number. The emulsion
obtained had a polymer content of 38.9 wt.%.
PolYacrYlate Example 2
In the stirred apparatus described in Polyacrylate
Example 1, while 3 liters of N2/h were passed over, 542.7 parts
of distilled water, 3.9 parts of emulsifier 1 and 0.75 parts of
emulsifier 2 were charged, and the mixture was heated to 80C
with intensive stirring. At 80C, a solution of 1.25 parts of
ammonium peroxodisulphate and 11.25 parts of water was added
and the mixture was stirred for exactly 5 minutes. 10 vol% of
a monomer mixture containing 41.6 parts of styrene, 90 parts of
methyl methacrylate, 113.3 parts of n-butyl acrylate, 39.0
parts of hydroxyethyl methacrylate, 80 parts of methacrylic
acid and 7.4 parts of dodecyl mercaptan, were added at the same
time at 80'C. After 15 minutes stirring at 80C, the remainder
of the monomer mixture was added dropwise in 2 hours.
After the addition was complete, a solution of 0.25 parts
of ammonium peroxodisulphate in 12.25 parts of water was added
dropwise in 10 minutes and the mixture was stirred for a
further 2 h at 80'C. The emulsion obtained had a polymer
content of 40.0 wt.%. The acid number of the polymer was 141.8
mg KOH/g. By dropwise addition of a 20 % solution of
N,N-dimethy1ethanolamine in butoxyethanol, the emulsion was 15%
neutralized, based on the acid number. The emulsion obtained
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was filtered through a Seitz clarifying bed T5500. The polymer
content of the filtered solution was 40.9 wt.%.
PolYacrYlate Example 3
In the stirred apparatus described in Polyacrylate
Example 1s while 3 liters of N2/h were passed over, 544.8 parts
of distilled water, 3.9 parts of emulsifier 1 and 0.75 parts of
emulsifier 2 were charged and the mixture was heated to 80C
with intens;ve stirring. Then at 80C a solution of 1.25 parts
of ammonium peroxodisulphate in 11.25 parts of distilled water
lo was added and the mixture was stirred for exactly 5 minutes.
10 vol% of a monomer mixture containing 41.6 parts of styrene,
100 parts of methyl methacrylate, 113.3 parts of n-butyl
acrylate, 39 parts of hydroxyethyl methacrylate, 71.4 parts of
methacrylic acid and 7.4 parts of dodecyl mercaptan, were added
at the same time at 80C. After 15 m;nutes stirring at 80C,
the remaining monomer mixture was added dropwise in 2 hours.
After the addition, was complete a solution of 0.25 parts
of ammonium peroxodisulphate and 12.25 parts of distilled water
was added dropwise. The mixture was allowed to react for a
further 2 h at 80C with intensive stirring. The emulsion
obtained had an acid number of 52.4 mg KOH/g and a polymer
content of 40 wt.%, which results in a calculated acid number,
based on solids, of 131 mg KOH/g. After cooling to room
temperature the emulsion was 15% neutralized, based on the
measured acid number, with a 20% solution of N,N-dimethyl-
ethanolamine in butoxyethanol. The emulsion obtained was
filtered through a Seitz clarify;ng bed T5500. The solids
content of the filtered solution was 39.2 wt.%.
PolYacrvlate Example 4
In the stirred apparatus described in Polyacrylate
Example 1, while 3 liters of N2/h were passed over, 557.8 parts
of distilled water, 3.9 parts of emulsifier 1 and 0.75 parts of
emulsifier 2 were charged and the mixture then heated with
intensive stirring to 80C. Then at 80C a solution of 1.25
parts of ammonium peroxodisulphate in 11.25 parts of water were
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added and the mixture was stirred for exactly 5 minutes. 10
vol% of a monomer mixture containing 62.4 parts of styrene, 100
parts of methyl methacrylate, 113.3 parts of n-butyl acrylate,
39.0 parts of hydroxyethyl methacrylate, 63.96 parts of
methacrylic acid and 7.4 parts of dodecyl mercaptan, were added
at the same time at 80C. After 15 minutes stirring at 80C,
the remaining monomer mixture was then added dropwise in 2
hours.
After the addition was complete, a solution of 0.25 parts
lo of ammonium peroxodisulphate in 12.25 parts of water was then
added dropwise in 10 minutes, followed by further stirring for
2 hours at BOC. The emulsion obtained had a polymer content
of 40.0 wt.%. The acid number of the polymer was 146.8 mg
KOH/g. By dropwise addition of a 20% solution of N,N-
dimethylethanolamine butoxyethanol, the emulsion was 15%
neutralized, based on the given acid number. The emulsion
obtained was filtered through a Seitz clarifying bed T5500.
The polymer content of the filtered solution was 39.3 wt.%.
Polvacrvlate Example 5
In the stirred apparatus described in Polyacrylate
Example 1, while 3 liters of N2/h were passed over, 590.25
parts of distilled water, 3.9 parts of emulsifier and 0.75
parts of Emulsifier 1 were charged and then heated to 80C with
intensive stirring. A solution of 1.25 parts of ammonium
peroxodisulphate in 11.25 parts of distilled water was added
and the mixture was stirred for exactly 5 minutes. 10 vol% of
a monomer m~xture containing 65.5 parts of styrene, 52.5 parts
of methyl methacrylate, 141.3 parts of n-butyl acrylate, 72.3
parts of hydroxyethyl methacrylate, 63.96 parts of methacrylic
acid and 7.4 parts of dodecyl mercaptan, were added at the same
time at 80-C. After 15 minutes stirring at 80C, the rest of
the monomer mixture was then added dropwise in 2 hours.
After the addition was complete, a solution of 0.25 parts
of ammonium peroxodisulphate and 12.25 parts of distilled water
was then added dropwise. The mixture was allowed to react
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further for another 2 h at 80C with intensive st;rring. The
emulsion obtained had an acid number of 42.8 mg KOH/g and a
polymer content of 40 wt.%, resulting in a calculated acid
number, based on solids, of 107 mg KOH/g. After cooling to
room temperature the emulsion was 15% neutralized, based on the
measured acid number, with a 20% solution of N,N-dimethyl-
ethanolamine in butoxyethanol. The emulsion obtained was
filtered by a Seitz clarifying bed T5500. The solids content
of the filtered solution was 38.6 wt.%.
Lacquer ExamDles
Coating compositions were prepared by mixing the emulsions
from Polyacrylate Examples 1, 4 and 5 with glycidyl ether A.
The components were mixed in a ratio of copolymer to glycidyl
ether of 100:50 and 100:30, respectively. Glycidyl ether A was
stirred by hand into the aqueous emulsion. The crosslinkable
coating compositions obtained had the following compositions
(Examples 1 to 6):
Example 1
Copolymer:glycidyl ether A ratio - 100:30, corresponding
to an equivalent ratio of unneutralized carboxyl groups to
epoxide groups of 1:1.
34.8 wt.% copolymer according to Polyacrylate Example 1
1.0 wt.% N,N-dimethylethanolamine
3.8 wt.% butoxyethanol
0 3 wt.% emulsifier 1
0.1 wt.% emulsifier 2
10.5 wt.% glycidyl ether A
49.5 wt.% water
100.0 wt.%
Example 2
Copolymer:glycidyl ether A ratio - lOO:SO, corresponding
to an equlvalent ratio of unneutralized carboxyl groups to
epoxide groups of 1:1.55.
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32.5 wt.% copolymer according to Polyacrylate Example 1
0.9 wt.% N,N-dimethylethanolamine
3.6 wt.% butoxyethanol
0.3 wt.% emulsifier 1
0.1 wt.% emulsifier 2
16.3 wt.% glycidyl ether A
46 3 wt % water
100.0 wt.%
Examole 3
lo Copolymer:glycidyl ether A ratio - 100:30, corresponding
to an equivalent ratio of unneutralized carboxyl groups to
epoxide groups of 1:1.27.
34.7 wt.% copolymer according to Polyacrylate Example 1
1.2 wt.% N,N-dimethylethanolamine
4.7 wt.% butoxyethanol
0.3 wt.% emulsifier 1
0.1 wt.% emulsifier 2
10.5 wt.% glycidyl ether A
48.5 wt.% water
1OO.O wt.%
Example 4
Copolymer:glycidyl ether A ratio - 100:50, corresponding
to an equivalent ratio of unneutralized carboxyl groups to
epoxide groups of 1:1.23.
32.4 wt.% copolymer according to Polyacrylate Example 4
1.1 wt.% N,N-dimethylethanolamine
4.4 wt.% butoxyethanol
0.3 wt.% emulsifier I
0.1 wt.% emulsifier 2
16.4 wt.% glycidyl ether A
45.3 wt.% water
100.0 wt.%
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Example 5
Copolymer:glycidyl ether A ratio - 100:30, corresponding
to an equivalent ratio of unneutralized carboxyl groups to
epoxide groups of 1:1.07.
34.6 wt.% copolymer according to Polyacrylate Example 5
0.9 wt.% N,N-dimethylethanolamine
3.5 wt.% butoxyethanol
0.3 wt.% emulsifier 1
0.1 wt.% emulsifier 2
10.4 wt.% glycidyl ether A
50.2 wt.% water
100.0 wt.%
Example 6
Copolymer:glycidyl ether A ratio - 100:50, corresponding
to an equivalent ratio of unneutralized carboxyl groups to
epoxide groups of 1:1.67
32.2 wt.% copolymer according to Polyacrylate Example 5
0.8 wt.% N,N-dimethylethanolamine
3.3 wt.% butoxyethanol
0.3 wt.% emulsifier 1
0.1 wt.% emulsifier 2
16.2 wt.% glycidyl ether A
47.0 wt.% water
100.0 wt.%
Each of these coating compositions were spread at a wet
film thickness of 180 ~m onto glass plates and then were each
cured for 30 minutes at 80 and 120-C. Glossy, crosslinked
films were obtained which possessed good scratch resistance.
The films cured at 80 C showed an advantageous post-curing at
room temperature, so that after 2 to 3 days, partial solubility
was no longer observed. The films dried at 120C were
completely resistant to solvent immediately after cooling.
Water resistance was carried out by laying a wet cotton
ball, covered with a Petri dish on the films cured at 120C.
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The film was then tested hourly for changes at the point of
contact. After 6 hours, no changes were observed.
Example 7
100 parts of the resin from Polyacrylate Example 1 having
a solids content of 39.7 wt.% were intensively stirred with
11.7 parts of glycidyl ether A. A transparent two-component
coating composition was formed with a ratio of carboxyl to
epoxide groups of 1:1. The processing time of the batch
exceeded 24 h. The coating composition had the following
lo composition:
Binder solid: 46.02 wt.%
Water: 50.40 wt.%
Organic solvent:3.58 wt.%
100.00 wt.%
The film was applied in a wet film thickness of 200 ~m
(= 50 to 60 ~m dry) and dried overnight to a hard, completely
transparent film. The curing reaction was completely finished
after about 14 days at room temperature. The properties of the
liquid coating composition and the fully cured film were as
20follows:
Liquid Coatinq Composition
Processing time (without loss of film properties) > 24 h
Dust free drying (sand drying) 1.5 h
Pressure drying (pressure with finger-tip) 5 h
25Coatinq
Film optics: gloss very good
transparency very good
Pendulum hardness (DIN 53157): 146 sec.
Solvent resistance:
3o - White Spirit very good
- solvent naphtha 100 very good
- methoxypropyl acetate very good
- acetone moderate
- ethanol good-moderate
Water resistance (24 h action) good
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Example 8
Example 7 was repeated with the exception that to
accelerate the reaction 0.23 parts of tris-(dimethylamino-
methyl)-phenol (Accelerator DMP 30, Rohm and Haas company,
Frankfurt/M.) were added. The properties of the liquid coating
composition and the fully cured film were as follows:
Liquid Coating Compo tion
Processing time: > 24 h
Dust free drying: 0.5 h
lo Pressure dry;ng: 1.0 h
Coating
Film optics: gloss very good
transparency very good
Pendulum hardness (DIN 53157) 150-160 sec
Solvent resistance:
- White Spirit very good
- solvent naphtha 100 very good
- methoxypropyl acetate very good
- acetone moderate
- ethanol very good
Water resistance (24 h. action) good
Example 9
Example 7 was repeated with the exceptlon that the coating
composition was hardened for 30 min. at 120-C instead of at
room temperature. The properties of the fully cured film were
as follows:
Film optics: gloss very good
transparency very good
Pendulum hardness 160-170 sec.
Mo3923
`` 2~ 6~
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Solvent resistance:
- White Spirit very good
- solvent naphtha 100 very good
- methoxypropyl acetate very good
- acetone very good
- ethanol good
Water resistance good
Example 10
100 parts of the resin from Polyacrylate Example 2 having
lo a solids content of 40.8 wt.% were stirred with 21.32 parts of
a commercial titan;um diox;de, rutile type (Bayert;tan R-KB-4,
Bayer AG Leverkusen) and then subjected to dispersion in a
dissolver for 30 minutes at a rotation speed of 15 to 20 m/sec.
The resulting dispersion component was suitable for use in a
two-component white coating composition and had practically
unlimited storability. The use of further dispersing additives
was unnecessary. To 121.32 9 of this dispersion component was
added 12.30 9 of glycidyl ether A and the mixture was stirred
until homogeneous. The ratio of carboxyl to epoxide groups was
20 1:1. The coating composition had the following composition:
Binder, solid39.74 wt.%
Pigment15.95 wt.%
Water 40.19 wt.%
Organic solvent4.12 wt.%
100.00 wt.%
The coating composition was applied in a wet film
thickness of 200 ~m (= 50 to 60 ~m dry). After drying
overnight, a hard, glossy coating was obtained. The curing
reaction was completely finished after a drying time of 10 to
3o 14 days. The properties of the llquid coating composition and
of the completely cured film were as follows:
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2~99$~
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Liquid Coating Composition
Processing time (without loss of film properties) 10-15 h
~ustfree drying (sand drying): 0.5 h
Pressure drying (pressure with finger tip) 1-1.5 h
Coating
Film optics: gloss very good
Pendulum hardness 150-160 sec.
Solvent resistance:
- White Spirit very good
lo - solvent naphtha 100 very good
- methoxypropyl acetate very good
- acetone good
- ethanol very good
Water resistance (24 h action) good
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
without departing from the spirit and scope of the invention
except as it may be limited by the claims.
Mo3923
