Note: Descriptions are shown in the official language in which they were submitted.
2~7~10~
Copolymer solutions based on addition products of
~,B-unsaturated car~oYvlic acid ~7ith qlycidyl esters
and copolymerisable ~ B-unsaturated monomers
The invention relate6 to copolymer solutions
based on addition products of ~ unsaturated carboxylic
acid with glycidyl esters and copolymerisable
~ unsaturated monomers with and without hydroxyl
groups. It also relates to the preparation of such
hydroxyl-containing copolymers and to the use thereof in
clear or pigmented coatings.
Hydroxyl-containing copolymers based on (meth)-
acrylates and reaction products of acrylic acid and
glycidyl esters of ~-alkylalkanemonocarboxylic acids
and/or ~ dialkylalkanemonocarboxylic acids which can be
processed together with organic polyisocyanates to form
coatings are known. DE-B-l 668 510 describes copolymers
of addition products of ~ ethylenically unsaturated
carboxylic acids with glycidyl esters and copolymerisable
~ unsaturated monomers with and without hydroxyl
groups. DE-C-2 603 259 di~closes two-component coatings
containing specific binders. The~e binders are copolymers
based on styrene, methyl methacrylate, acrylic acid and
glycidyl esters of ~-alkylalkanemonocarboxylic acids
and/or ~ dialkylalkanemonocarboxylic acids obtained by
heating with simultaneous esterification and polymerisa-
tion in inert solvents in the presence o~ polymerisation
initiators with or without chain terminators.
The solids contents of prior art copolymer
solutions on termination of the simultaneous esterifica-
tion and copolymerisation is not more than 55% by weightor, according to page 4 of DE-A-3 740 774 (component A),
about 65% by weight, although the objective of the latter
reference was a particularly high solids content.
The object of the invention is5 l. To provide copolymer solutions which have a signi~i-
cantly higher solids content,
2. To provide processes for preparing the novel copoly-
mer solutions,
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3. The binders obtainable from the novel copolymer
solutions shall when used with difunctional and/or
higher polyisocyanates have an increased solids
content for the same viscosity. This means that the
two-component coating~ prepared from the copolymer
solutions or the binder of the invention can be
applied quickly, for example ~y omitting one or more
spraying operations. Furthermore, because of the
higher solids content of the re~dy-prepared two-
component coatings less organic solvent shall be
emitted into the environment.
4. The copol~mer solutions or binders, when combined
with aliphatic polyisocyanates, shall produce air-
and oven-drying high-solids two-component finishes
lS of high mechanical, chemical, weathering and ultra
violet radiation resistance.
5. The provision of copolymer solutions or binders or
clear or pigmented coatings with an increased solids
content that lead to coatings of high gloss, good
build, good flow, less environmental pollution and
improved processing reliability.
6. The copolymer solutions or binders shall be proces-
sible into two-component coatin~s highly suitable
for use not only as automotive original equipment
coatings but also as automotive re~inish coatin~s.
7. The binders mentioned earlier under point 3 shall
result in improved clear coatings for automotive
topcoating by producing paint films with excellent
abrasion resistance in car washes.
8. The novel polymer solutions shall also be combinable
with amino resins to form binders which are pro-
ce~sed to form baking finishes with or without
pigments. It shall also be possible to add polyiso-
cyanates to the copolymer-amino resin combina~ion.
Again, the foregoing binders are suitable ~or
improved clear baking finishes ~or automotive
topcoating which provide paint films with excellent
abrasion resistance in car washes.
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It has been found that this object is achieved by
providing a copolymer solution which contains a hydroxyl-
containing copolymer based on addition products of
e,~-unsaturated carboxylic acid with glycidyl esters and
copolymerisable Q,~-unsaturated monomers with and without
hydroxyl groups, said copolymer being characterised in
that it consists essentially of a hydroxyl-containing
copolymer obtainable from
a) 10 to 30% by weight of glycidyl esters of e~alkyl~
alkanemonocarboxylic acids
and/or e,e~dialkylalkane~
monocarboxylic acids,
b) 5 to 12% by weight of methacrylic acid,
c) 10 to 27% by weight of hydroxyalkyl methacrylate
having 1 to 6 carbon atoms in
the hydroxylalkyl radical,
d) lO to 38% by weight of styrene,
e) 1 to 5% by weight of polypropylene glycol mono-
methacrylate having an average
molecular weight of 350 to 387~
f) 3 to 20% by weight of alkyl methacrylate having 1
to 8 carbon atoms in the alkyl
radical,
g) 9 to 20% by weight of solvent-free, reactive,
methoxy-functional polysiloxane,
the percentages of components a,
b, c, d, e, f and g always
adding up to 100% by weight.
An advantageous embodiment of the copolymer is
obtainable fro~:
a) 17 to 25% by weight of glycidyl esters of ~-alkyl-
alkanemonocarboxylic acids
and/or e~e~dialkylalkane
monocarboxylic acids,
b) 7 to 12% by weight of methacrylic acid,
c) 15 to 26% by weight of 2 hydroxyethyl methacrylate,
d) 17 to 28% by weight of styrene,
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e) 1 to 3% by weight of polypropylene glycol mono-
methacrylate having an average
molecular weight of 350 to 387,
f) 5 to 15% by weight of methyl methacrylate,
S g) 12 to 17% by weight of solvent-free, reactive,
methoxy-functional polysiloxane,
the percentages of components a,
b, c, d, e, f and g always
adding up to 100% by weight.
A preferred embodiment of the copolymer is
obtainable from:
a) 18 to 24% by weight of glycidyl esters of ~-alkyl-
alkanemonocarboxylic acids
and/or ~,~-dialkylalkane-
monocarboxylic acids,
b) 6 to 12% by weight of methacrylic acid,
c) 17 to 22~ by weight of 2 hydroxyethyl methacrylate,
d) 20 to 28~ by weight of styrene,
e) l to 3% by weight of polypropylene glycol mono-
methacrylate having an average
molecular weight of 350 to 387,
f) 8 to 12% by weight of methyl methacrylate,
g) 12 to 17% by weight of solvent-free, reactive,
methoxy-functional polysiloxane,
the percentages of components a,
b, c, d, e, f and g always
adding up to 100% by weight.
Another preferred embodiment of the copolymer
solution is obtainable from:
a~ 8 to 22% by weight of glycidyl ester~ of ~-alkyl-
alkanemonocarboxylic acids
and/or ~ dialkylalkane-
monocarboxylic acids,
b) 7 to IO% by weight of methaorylic acid,
c) 19 to 22% by weight of 2-hydroxyethyl methacrylate,
d) 20 to 2~% by weight of styrene,
e) 1 to 3% by weight o~ polypropylene glycol mono-
methacrylate~having an average
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molecular weight of 350 to 387,
f) 9 to 11% by weight of methyl methacrylate,
g) 13 to 17% by weight of solvent-free, r~active,
methoxy-functional polysiloxane,
the percentages of components a,
b, c, d, e, f and g always
adding up to 100% by weight.
The most preferred embodiment of the above-
mentioned copolymer solutions is characterised in that,
after its preparation, it consists of
A) 15.0-25.0% by weight, preferably 15 to 20~ by weight,
of customary inert paint sol-
vents, preferably with boiling
points of 150 to 2D0~C, and
B) 75.0-85.0% by weight, preferably 85 to 80% by weight,
of hydroxyl-containing
copolymers.
It has been ~ound that such a copolymer solution,
when used with difunctional and/or higher polyisocyanates
produces, compared with the prior art, an increased
solids content for the same viscosity or a reduced vis-
cosity for the same solids content. What is more, it has
coating advantages, such as improved glo5s~ build, flow,
processing reliability as well as the high solids con-
tent, and also better environmental properties.
The copol~mer solution of the invention isprepared by solution polymerisation. This involves an
addition reaction between components a and b with a
simultaneous condensation with component g by elimination
of methanol, which is removed in the reflux of the
boiling reaction mixture. This process comprises intro-
ducing the solvents and the glycidyl esters of ~-alkyl-
alkanemonocarboxylic acid~ andlor ~ dialkylalkane-
monocarboxylic acids into the reaction ves~el as initial
charge, heating to the boilj and continuously adding the
mixture or mixtures of monomers, optionally carboxy~epoxy
catalysts and initiator continuou~ly over about 12-20
hours. On completion o~ the metered addition the
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20741 D~
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polymerisation temperature is maintained for a further 2
to 5 hours - with or without the addition of further
polymerisation initiator - until conversion is virtually
complete. The polymerisation is carried out at tempera-
tures between 140 and 195C, preferably at 160 to 190C,
the reaction being initiated at about 180 to 190C. The
temperature decreases in the course o~ the simultaneou~
copolymerisation, addition and condensation.
In a preferred embodiment, illustrated by the
Examples, a mixture of inert solvents is introduced as
initial charge and heated to the boil under reflux, the
inert solvents having been selected in such a way that
the reflux temperature is about 188C. Following initia-
tion of the copolymerisation and towards the end of the
metered addition time, the boiling temperature of the
copolymer solution decreases to about 170C to about
140C. The metered addition i9 then followed by holding
the temperature at 170C to about 140C until conversion
is virtually complete and the desired solids content
(about 80% in the Examples~ has been obtained.
The polymerisation reaction is initiated with
known polymerisation initiators. Suitable initiators are
~or example peroxides which decompose thermally into free
radicals by a 1st order reaction. Initiator type and
amount are chosen in such a way that a very constant
supply of free radicals is present at the polymerisation
- temperature during the metered addition phase.
Preferred initiators for the polymerisation are:
dialkyl peroxides, such as di-tert-butyl peroxide,
dicumyl peroxide; hydroperoxides, such as cumene hydro-
peroxide, tert-butyl hydroperoxide; peresters, such as
tert-butyl perbenzoate, tert-butyl per-3,5,5-trimethyl-
hexanoate, tert-butyl per-2-ethylhexanoate.
The polymerisation initiators, iA particular
tert-butyl per-2-ethylhexanoate, are pre~erably added in
an amount o~ 2 to 6% by weight, based on the weight of
monomer used.
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The molecular welght may be regulated using chain
trans~er agents~ Examples are mercap~ans, thioglycolic
esters and chlorohydrocarbons, preference being given to
dodecylmercaptan.
Suitable solvents ~or the solution polymerisation
are customary inert paint solvents alone, preferably
mixed, with boiling points of 150C to 200C, preferably
154C to 200C. The preferr~d organic solvents are those
which later are also used in the ready-prepared coatings.
Examples of such solvents are: glycol ethers, such as
ethylene glycol dimethyl ~her; glycol ~ther esters, such
as ethylglycol acekate, butylglycol acetate, 3-methoxy-
n-butyl acetate, butyldiglycol acetate, methoxypropyl
acetate; ethoxypropyl acetate, esters, such as butyl
acetate, isobutyl acetate, amyl acetate; and ketones,
such as methyl ~thyl ketone, methyl isobutyl ketone,
diisobutyl ketone, cyclohexanone, isophorone, aromatic
hydrocarbons, such as xylene. Shellsol A (registered
trade mark for aromatic hydrocarbon mixtures) and ali-
~0 phatic hydrocarbons can likewise be used cut with theabovementioned solvents. Preference i9 given to using a
mixture of butyl glycol acetate, Shellsol A and ethoxy-
propyl acetate in a weight ratio of 1:2:2.
Component a) for preparing the hydroxyl-
containing copolymer solutions of the invention comprises
glycidyl esters of ~-alkylalkanemonocarboxylic acids
and/or ~,~-dialkylalkanemonocarboxylic acids. The gly-
cidyl esters preferably have the empirical formula Cl3H2403
individually or together.
Since the glycidyl radical in the glycidyl ester
of such ~-alkylalkanemonocarboxylic acids and/or ~ di
alkylalkanemonocarboxylic acids has the empirical formula
C3~50 ~ the ~ alkylalkanemonocarboxylic acids and ~ di-
alkylalkanemonocarboxylic acid~ are isomer mixtures of
those monocarhoxylic acids which contain a C10 chain.
These acids are preferably very highly substituted at the
~-disposed carbon atom and fully saturated; examples
thereo~ are described in Deutsche Farbenzeikschrift,
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No. 10/volume 16, page 435.
Suitable hydroxyalkyl methacrylates having 1 to
6 carbon atoms in the hydroxyalkyl radical are hydroxy-
methyl methacrylate, 2-hydroxyethyl methacrylate,
5 2-hydroxypropyl methacrylate, 4-butanediol monometh-
acrylate, 5-pentanediol monomethacrylate, cyclohexanediol
monomethacrylate and 4~dihydroxymethylcyclohexane mono-
methacrylate, alone or mixed, preference being given to
using 2-hydroxyethyl methacrylate.
The Yolvent-free, reactive, methoxy-functional
polysiloxan~ component g with a narrow molecular weight
distribution, a low average molecular weight and a very
low proportion of volatiles is Silicone Intermediate
SY 231 from Wacker-Chemie Gmb~, 8000 Munich 22.
lS Suitable carboxy-epoxy catalysts based on an
alkali metal compound are all sodium, lithium, potassium,
rubidium and caesium compounds - alo~e or mixed - which
are soluble in the reaction mixture of methacrylic acid~
monoglycidyl compound and vinyl compounds or at least
dissolve therein in the course of the metered addition
and/or in the course of the reaction b tch being main-
tained at the reaction temperature for the purpose of
esterification by addition with simultaneous copoly-
merisation, although the alkali metal compound used
should be free of constituents which may have an
unfavourable effect in the`course of the copolymerisation
o~ the addition product, which is an ester.
It is po3sible to use for example the carbonates,
bicarbonates, formatec, iodides, bromides, fluorides and
hydroxides of the aforementioned alkali metals. On a
~actory scale it is best to use lithium hydroxide and
potassium hydroxide, alone or mixed. Of these, potassium
hydroxide is particularly advantageous on a factory scale
on account o~ its low cost and excellent catalytic
properties. The alkali metal compound or hydroxide or
mixture is advantageously dissolved in the methacrylic
acid to be e~teri~ied. However, it is al50 possible first
to convert the alkali metal compound, e.g. alkali metal
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hydroxide, carbonate or bicarbonate, and the methacrylic
acid into the alkali metal salt thereof and then to
dissolve the alkali metal salt of methacrylic acid as
catalyst in the reaction mixture, if necessary by heating
in the course of the addition reaction.
It is in general sufficient to add from about
0.001% by weight to about 0.5~ by weight of alkali metal
compound of the a~orementioned kind, based on the weight
of the ester-forming components, for the addition reac-
tion. However, preference is given to an addition ofabout 0.001~ by weight to about 0.3~ by weight of alkali
metal compound.
The most preferred addition range extends from
about 0.005~ by weight to 0.1% by weight of an alkali
metal compound, in which case the alkali metal compounds
used are very particularly advantageously potassium and
lithium compounds.
Special studies have shown that, if an alkali
metal caxhoxy-epoxy catalyst, preferably an alkali metal
hydxoxide, carbonate or bicarbonate~ is used in preparing
the copolymer solution, the coating compositions obtain-
able therefrom with polyisocyanates have special,
unforeseeable properties. For instance, such two-
component coating compositions have a longer pot life and
the coatings produced therefrom have a better ageing
resistance as regards the loæs in elasticity.
The copolymer solutions according to the inven-
tion can be processed into clear or pigmented coating
compositions. For this they are admixed in solvents with
a customary coatings polyisocyanate in the presence or
absence of customary coatings additives and auxiliaries.
Preferably, 60.0 to 80.0~ by weight of the hydroxyl-
containing copolymer B is admixed with 20 to 40% by
weight of a difunctional and/or higher polyisocyanate as
component C; the percentages of components B and C always
add up to 100%.
The polyisocyanates C uiable for crosslinking the
copolymer B according to the invention are typical
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coatings polyisocyanates.
The proportion of polyisocyanate crosslinker is
chosen in such a way that from 0.5 to 1.5 isocyanate
groups are added per hydroxyl group of the binder mix-
ture. Excess isocyanate groups can react with moistureand contribute to the crosslinking.
It is possible to use aliphatic, cycloaliphatic
and aromatic polyisocyanates such as hexamethylene
diisocyanate, trimethylhexamethylene diisocyanate,
isophorone diisccyanate, 4,4~-diisocyanatodicyclohexyl-
methane, toluylene 2,4-diisocyanate, o-, m- and
p-xylylene diisocyanate, 4,4'-diisocyanatodiphenyl-
methane; blocked polyisocyanates, such as polyisocyanates
blocked with acidic CH, NH or OH compounds; and also, for
example, polyisocyanates with biuret, allophanate~
urethane or isocyanurate groups. Examples of such poly-
isocyanates are a biuret formed from 3 mol of
hexamethylene diisocyanate with 1 mol of water and having
an NCO content of about 22% (corresponding to the commer-
cial product Desmodur N BAYER AG, registered trade mark);a polyisocyanate with isocyanate groups, prepared by
trimerisation of 3 mol of hexamethyler.e diisocyanate and
having an NCO content of about 21.5% (corresponding to
the commercial product ~esmodur N 3390 ~AYER AG,
registered trade mark) or polyisocyanates with urethane
groups, which are reaction products of 3 mol of toluylene
diisocyanate and 1 mol of trimethylolpropane and have an
NCO content o~ about 17.5% (corresponding to the commer-
cial product Desmodur L BAYER AG, registered trade mark).
Preference is given to using Desmodur N and
Desmodur N 3390, BAYER AG, registered trade mark.
As mentioned earlier, coating compositions
prepared from components ~ and C can be transparent or
pigmented. Transparent coating compositions find use for
example as clear coatings in a two-layer coating composed
of a pigment-containing basecoat and a transparent
topcoat, applied wet-on-wet and subsequently cured either
in air or in baking stoves. The~e clear coating
20~0~
compositions may, in addition to customary solven-ts for
controlling the spray viscosity, also contain customary
flow control agents and light stabilisers but also other
customary coatings additives.
The aforementioned transparent or pigmented coat-
ing compositions may contain as further hardeners from 1
to 10% by weight o reactive amino resins customary for
coatings.
To prepàre pigmented coating compositions, the
individual constituents are mixed with one another and
conventionally homogenised or ground. ~ possible pro-
cedure is for example first to mix some of the copolymer
solution with the pigments to be included and customary
coatings auxiliaries and solvents and then to subject the
mixture to milling.
The mill base is then completed with the remain-
ing copolymer solution.
The coating compositions obtained from the
hydroxyl-containing copolymer solution according to the
invention have the considerable advantage of a high
solids content coupled with a relatively low viscosity.
Their flow-out properties are excellent and they lead to
paint films of excellent gloss and outstanding build. The
paint films obtained are very rapidly assemblyproof and
abhesive to adhesive tape, permitting for example
multiple coating. The coa~ing compositions obtainable
from the copolymer solutions according to the invention
are thu~ particularly suitable for use in the automotive
industry for coating motor car bodies, but also suitable
in the re~iniæhing sector for the rapid repair of, for
example, acoident damage.
The copolymer solutions of the invention can be
combined with amino resins to form binders which are
suita~le for baking finishes. Suitable amino reæins are
the known reaction products o~ aldehydes, in particulax
formaldehyde, with substances carrying a plurality of
amino or amido groups, for example melamine, urea,
N,N'-ethyleneurea, dicyandiamide or benzoguanamine,
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obtained by etherification with alcohols, in particular
with n-butanol or isobutanol, in particular melamine-
formaldehyde condensates, for example a melamine-
formaldehyde condensate which has been etherified with
isobutanol in an average molar ratio of 1 melamine-
6-formaldehyde to 3 mol of isobutanol. For instance, a
baking clearcoat finish can consist of50to60~ by weight
of customary coatings solvents, of25to44% by weight of
copolymers of the invention,19to4 ~ by weight of an amino
resin, as well as customary baking finish additives.
Embodiments of the invention will now be more
particularly described by way of example.
Preparation of copolymer solution
A 4-1 three-necked flask equipped with a stirrer,
a contact thermometer, a spherical condenser with a
reflux trap for methanol and any other ellmination
products, and 2 dropping funnels is charged with con-
stituent I in accordance with the quantitative data given
below in the table and the contents are heated with
stirring and under switched-on reflux cooling to about
180 to 190C. Constituent II (monomer mixture and XOH as
carboxy-epoxy catalyst and optionally a chain transfer
agent) and constituent II~ (solvent-initiator mixture)
are metered in continuously from dropping funnels 1 and
2 in the course of 16 hours. The temperature decreases
from 188C towards the end of the addition time to about
160 to about 165C. On completion of the metered addition
a temperature of about 160 to 167C is maintained for 3
hours, during which if necessary further polymerisation
initiator is added after one hour, so that conversion is
virtually complete~
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Table
(weights in grams)
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Copolymer 1 Copolymer 2 Copolymer 3
Constituent
I ButYlqlvcol_acetate 100 100 100
Ethoxvpropvl acetate 160 160 160
Mixture of aromatic
hydrocarbons
(Shellsol A, regis-
tered trade mark) 200 200 200
Glycidyl ester
(Cardura E 10, regis-
tered trade mark) 400 _ 400 400
II MethacrYlic acid . 182 182 182
2-Hydroxyethyl
methacrYlate 420 478 536
Stvrene 478 360 247
Polypropylene glycol
monomethacrvlate* 20 20 21
MethYl methacrvlate 200 _ 160 _ 114
Potassium hydrox;de 0.1 0.1 0.1
Silicone Intermediate
SY 231 _ _ _ _ _ 300 400 500
III Ethoxvpro~Yl acetate 40 40 40
tert-Butyl
per-2-ethvlhexanoate 80 _ 80 80
Parameters:
Solids content (%): 80 80 80
Viscosity~ DIN 4 cup
after dilution with
butyl acetate to 60%
by wei~ht sollds 60-90 sec. 81-86 sect70-100 sec.
35 Acid number~ (based
on resin solids?: 16.4-19.3 .18.9-20 20.6
OH number~ (based on
resin solids), _ _ _ 125-17Q 156 150 _ _
~ Average molecular weight from 350 to 387
.
~ Range of variation obtained in numerous repeats of
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First studies have shown that the copolymer
solution can be prepared under the stated conditions ~ven
in the absence of carboxy-epoxy catalysts.
Preparation of clear coating from copolymer solution 1
In a clean, dry vessel 800 g of bu-tyl acetate,
850 g of xylene, 1050 g of a mixture of aromatic hydro-
carbons tShellsol A trade mark), 150 g of light
stabiliser (trade name Tinuvin~ 1130), 100 g of light
stabiliser (trade name Tinuvin~ 292), 50 g of 5% strength
dibutyltin dilaurate solution in xylene as accelerator
and 200 g of flow-control agent (trade name Byk~ 300 10%
strength in xylene) are thoroughly mixed. Then 6800 g of
copolymer solution 1 (previously adjusted from 80% by
weight solids to 75~ by weight solids with butyl acetate)
are add~d and thoroughly mixed in. Then 3000 g of the
coatings polyisocyanate Desmodur~ N 3390, 80% solution in
1:1 xylene/butyl acetate, are added to the batch and
thoroughly mixed in, and the viscosity of the mixture is
immediately determined in a DIN 4 cup~ The batch is
diluted with 1:1 Shellsol~ A/butyl acetate to a spray
application viscosity corresponding to an efflux time of
21 seconds.
The solids content of the aforementioned clear
coating is 54.8~ by weight. This represents a distinct
improvement over the prior art solids content of only
50.2% by weight. Further tests o the clear coating have
shown that it has improved performance characteristics.
Applied to test panels and, a~ter flash-off, heated at
80C for 45 minlltes, it produced a pendulum hardness of
120 seconds and heated at 130C for 30 minutes after
flash-off it produced a pendulum hardness of 157 seconds.
The measurement was carried out after standing for one
hour for the purpose of cooling.
Preparation of a white coating from copolymer solution 1:
In a clean, dry vessel 550 g of Shellsol~ A, 665 g
of butyl acetate 98/100, 200 g of antisettling agent
consisting of Bentone~ 38.10% strength in xylene and 4~
Anti-Terra~ U, 50 g of dibutyltin dilaurate 1% strength by
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weight in xylene, 2500 g of copolymer solutlon 1 (diluted
as indicated earlier to a solids content of 75% by
weight) and 375 g of wetting agent (trade name Byk~ 160
30% strength) are thoroughly mixed, and 2900 g of the
white pigment titanium dioxide 2160 are gradually added
with stirring and the mixture is then bead milled for
30 minutes with a bead ratio of 1:1. The batch are then
admixed with 15Q0 g of copol~mer solution 1, previously
adjusted to 75% by weight solids, 200 g of flow control
agent (Byk~ 344 10% strength by weight in xylene), 300 g
of deaerating agent (Byketol~ OK) and 760 g of n-butyl
acetate and thoroughly mixed. To this batch are added
1800 g of dilution Bd 1316 as solvent followed with
thorough stirring by 1800 g of the coatings polyiso-
cyanate Desmodur~N 3390 90% strength. The solids content
of the aforementioned white coating is 63% by weight.
This fact reveals that the coatings which contain the
copolymer solution according to the invention can be
applied within a shorter period (e.g. omission of spray-
ing operationS) and that the paint film produced none-
thsless has satisfactory performance characteristics and,
by virtue of the spraying being shortened, less organic
solvent is emitted into the environment. The aforemen-
tioned dilution Bd 1316 is obtained by mixing 2500 g of
ethoxypropyl acetate, 2500 g of n-~utyl acetate, 500 g of
butoxyl (- 3-methoxy-1-butyl acetate), 2500 g of xylene
and 2000 g of Shellsol~ A.
The pot life of the aforementioned white coating,
measured as the DIN 4 cup efflux time, was:
measured immediately following
preparation 21 second~
after 2 hours 27 "
after 4 hours 39 "
after 6 hours 58 "
after 8 hours 120 "
Steel panels coated with commercial primer were
overcoated after one day with the aforementioned white
coating and cured at 80C for 60 minutes. The properties
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were measured after 24 hours:
primer 24 ~m
coating 44 ~m
gloss ~ 60 93% measured to DIN 67530
and ISO 2813
Konig pendulum hardness 108/~ measured to DIN 53157
or ISO 1522
Buchholz hardness 87 measured to DIN 53153
or IS0 2815
Erichsen indentation7.5 mm measured to DIN 53156
or ISO 1520
adhesion (cross hatch test) Gt 0 measured to DIN 53151
or IS0 ~409
resistance
15 test 5' xylene pass
5' four-star
petrol unleaded pass
Resistance tests with xylene and unleaded four-star
petrol
A cotton wool swab soaked with xylene or unleaded
four-star petrol was placed on the baked film of the
white coating in the covered state and left for
5 minutes. After the cotton wool swab had b~en removed
and the test liquid wiped away, the dry tested film was
assessed. For a film to pass, as in the present case, it
must not show any changes.
Evaluation of aforementioned test results:
Despite the high solids content of the in-test
coating, the measured values show that the gloss, the
Konig pendulum hardness, the Buchholz hardness, the
Erichsen indentation, the cross hatch and the petrol
resistance tests all produced values which correspond to
tho~e of very good commercial products, which, however~
have the disadvantage that the coatings have only a lower
solid~ content. Any person skilled in the art knows that
as the sol~ds content of a coating increase~ ît is very
difficult to achieve the requixed high quality features
at all, so that the test results demon~trate surprising
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2~7~0~
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properties.
Preparation of a clear coating from copolymer solution 2
In a clean, dry ves~el 800 g of n-butyl ac~tate,
850 g o~ xylene, 1050 g of a mixture of aromatic hydro-
carbons (Shellsol A trade mark), 150 g of light stabi-
liser (trade name Tinuvin~ 1130), 100 g of light
stabiliser (trade name Tinuvin3 292), 50 g of a 5%
strength dibutyltin dilaurate solution in xylene as
accelerator and 200 g of flow control agent (trade name
Byk~ 300 10~ strength in xylene) are thoroughly mixed.
Then 6800 g of copolymer solution 2 (previously adjusted
from 80% by weight solids to 75% by weight solids with
butyl acetate) are added and thoroughly mixed in. Then
3000 g of coatings polyisocyanzte/Desmodur~ N 3390 dis-
solved in 80% strength in 1:1 xylene/butyl acetate are
added to the batch and ~horoughly mixed in and the
viscosity is determined at once in a DIN 4 cup. By
diluting with a l:l Shellsol~ A/butyl acetate mixture the
batch is adjusted to a spray application viscosity
corresponding to an efflux time of 21 seconds.
The solids content of the aforementioned clear
coating is 54.7% by weight. This represents a distinct
improvement over the prior art solids content of only
50.2% by weight. Further tests on the clear coating have
shown that it has Lmproved performance characteristics.
Preparation o~ a white coating from copolymer solution 2:
In a clean, dry vessel 5S0 g of Shellsol0 A, 665 g
o~ n-butyl acetate, 2nO g of an antisettling agent
comprising Bentone~ 38 10~ strength in xylene and 4% o~
Anti Terra0 U, 50 g of dibutyltin dilaurate 1% strength by
weight in xylene, 2500 g o~ copolymer ~olution 2 (diluted
to a solids content of 75% by weight as indicated above)
and 375 g o~ a wetting agent ttrade name Byk~ 160 30%
strength) are thoroughly mixed, and 2900 g of the white
pigment titanium dioxide 2160 are gradually added with
~tirring, and the mixture i~ introduced into a bead mill
and bead milled for 30 minute~ with a bead ratio of 1:1.
The batch i~ then admixed with 1500 g of copolymer
~.
- 18 - 20 7~ 1 Q4
solution 2 (adjusted to 75% solids), 200 g of a ~low
control agent (Byk3 344 10% strength by weight in xylene),
300 g o~ a deaerating agent (Byketol~ OK) and 760 g of
butyl acetate and ~horoughly mixed. To this batch are
added 1800 g of dilution Bd 1316 as solvent followed with
thorough stirring by 1800 g of coating polyisocyanate
Desmodur~ N 3390 90% strength. The solids content of the
aforementioned white coating is 63.5~ by weight. This
fact shows that coatings which contain the copolymer
solution of the invention can be applied within a shorter
time (for example through omission of spraying opera-
tions) and that the paint film produced nonetheless has
satisfactory performance characteristics and less organic
solvent is emitted into the environment by virtue of the
shortening of the spraying operation.
The pot life of the aforementioned white coating,
measured as efflux time from the DIN 4 cup, was:
measured immediately following
preparation 21 seaonds
after 2 hours 33
a~ter 4 hours 54 "
after 6 hours 120
Steel panels coated with ~ommercial primer were
overcoated after one day with the aforementioned white
coating and cured at 80C for 60 minutes. The properties
were measured after 24 hours:
primer 22-26 ~m
coating 44-51 ~m
gloss ~ 60 93~measured to DIN 67530
or ISO 2813
Xonig pendulum hardness 114~ measured to DIN 53157
or ISO 1522
Buchholz hardnes~ 87measured to DIN 53153
or ISO 2815
Erichsen indentation6.8 mm measured to DIN 53156
or ISO 1520
adhesion (cross hatch test) Gt 0 measured to DIN 53151
or ISO 2409
,
.
- 19 - ~07~
resistance
test 5~ xylene pass
5~ fo~r-star
petrol unleaded pass
The aforementioned test results likewise show the
surprising properties of th~ films compared from the
white coating based on copolymer solution 2, as demon-
strated earlier at length with the films of white coating
based on copolymer solution 1.
Preparation of an amino resin clear coating from copoly-
mer solution 1:
In a clean, dry vessel 400 g of aromatic hydro-
carbons (Shellsol A trade mark~, 35 g of light sta~ er
(trade name Tinuvin~ 1130), 35 g of light stabiliser
(trade name Tinuvin~ R 292) and 200 g of a flow control
agent (trade name Byk~ 300 10% strength in xylene) are
thoroughly mixed. Then 5600 g of copolymer solution 1
(previously adjusted from 80% by weight solids to 75% by
weight solids with butyl acetate) are added and thorough-
ly mixed in. Then 373 g of melamine resin BE 683 are
added to the batch and thoroughly mixed in and the
viscosity is determined at once in a DIN 4 cup. By
diluting with a mixture of 30 g of xylene, 20 g of
n-butanol and 35 g of Solvesso~ 150 and 5 g of ethoxy-
propyl acetate the batch is adjusted to a spray applica-
tion viscosity corresponding to an efflux time of 21
seconds.
The solids content of the aforementioned clear
coating is 43.6% by weight. This represents a distinct
improvement over the prior art solids content of only 40%
by weight. Further tests on the clear coating have shown
that it has improved performance characteristics. Applied
to test panels and, after drying, baked at 130C for
30 minutes, the clear coating resulted in a pendulum
hardne~s of 128 seconds.
Preparation of an amino re~in clear coating ~rom
copolymer solution 1:
- , ~
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, ~
,
- 20 - 2~7~Q~
In a clean, dry vessel 400 g of aromatic hydro-
carbons (Shellsol A trade mark), 35 g of ligh~ stabiliser
(trade name Tinuvin3 1130), 35 g of light stabiliser
(trade name Tinuvin~ R 292) and 200 g of a flow control
5 agent (trade name Byk0 300 10~ strength in xylene) are
thoroughly mixed. Then 6530 g of copolymer solution 1
(previously adjusted from 80% by weight solids to 75~ by
weight solids with butyl acetate) are added and thorough-
ly mixed in. Then 280 g of melamine resin BE 683 are
added to the batch and thoroughly mixed in and the
viscosity is determined at once in a DIN 4 Cupt By
diluting with a mixture of 30 g of xylene, 20 g of
n~butanol and 35 g of Solvesso~ 150 and 5 g of ethoxy-
propyl acetate the batch is adjusted to the spray
vi~cosity corresponding to an efflux time of 21 seconds.
The solids content of the af orementioned clear
coating is 43.5% by weight. This represents a distinct
improvement over the prior art solids content of only 40%
by weight. Further tests on the clear coating have shown
that it has improved performance charactexistics. Applied
to test panels and, after drying, baked at 130C for
30 minutes, the clear coating resulted in a pendulum
hardness of 12 seconds.
The description, the examples, the coatings and
the experimentally determined data all show that the
above-stated objects of the invention are indeed
achieved.
The preparation of the copolymer solutions and of
the coatings involved the u~e of commercial products
which will now be more particularly described:
Shellsol~ A s~arts to boil at 166C and has an
aromatics content of 98~ by volume.
Tinuvin~ 1130 is a liquid W absorber ~ased on a
hydroxyphenylbenzotriazole derivative. It is the reaction
product of the following 2 components and has an average
molecular weight of MW > 600:
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207~
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~o
~N~ ~'` ~ HO (C~ CH~ 0~ ~,H
CH2 CH1 COOCH3 n = 6.7
Methyl 3-[3-(2H-benzo- Polyethylene glycol 300
triazol-2-yl)-5-tert-butyl-
4-hydro~yphenyl~propionate
~ TINUVIN 1130
Tinuvin~ 292 is a liquid light stabiliser,
developed ~or the light stabilisation of industrial
coatings. Tinuvin0 292 i~ a member of the class of the
sterically hindered amines (HALS). It has the advantage
of not being sensitive to acid-catalysed systems which
are used as automotive refinishes with low baking
temperatures.
BYK0-300 is an additive for increasing the scratch
and mar resistanc~ and it is based on a 50% strength
solution of a specific, ~oating-compatible polysiloxane
copolymer. It is manufactured by Byk-Chemie GmbH in
D-4230 Wesel.
BYK~-344 is an additive for increasing the scratch
and mar resistance, and it is a 50% strength solution of
a specific, modified, coating-compatible siloxane
copolymer.
Density at 20C (DIN 51757) 0-93-0-95 g/cm3
Refractive index ~DIN 53491) 1.463-1.468
Nonvolatiles (ASTM D1644~) 48-50%
25 Solvent 4:1 xylene/isobutanol
Flashpoint (DIN/ISO 3679) 23C
Appearance clear or slightly cloudy
liquid
Manufacturer: BYX-Chemie Gmb~
BYKETOL~-OK is a flow control additive based on
a mixture of high boiling aromatics, ketones and esters.
Den ity at 20C (DIN 51757) 0.8~-0.87 g/cm3
Refractive index (DIN 53491) 1.468-1.474
.,,. .... , ... :
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~7~1Q4
- 22 -
Flashpoint (DIN/ISO 3679) 42C
Appearance clear or slightly cloudy
liquid
Manufacturer: BYK-Chemie GmbH
Silicone Intermediate SY 231 is a solvent~free,
reactive, methoxy-functional polysiloxane having a narrow
molecular weight distribution, a low average molecular
weight and a very low volatiles content. Silicone Inter
mediate SY 231 is a clear, slightly yellowish liquid
having an alkoxy equivalent of 222, a total silicone
content (all methoxy groups replaced by Si~O-Si bonds) of
89% by weight, a viscosity at 25C of 100-150 mm2/s, a
density at 25C of 1.14 g/ml, a refractive index at 25C
of 1.500-1.505, and a volatiles content (5 g/1 h/150C)
of 2~ ~y weight.
Manufacturer: Wacker-Chemie GmbH, 8000 Munich 22.
BE 683 A is an n-butylated melamine resin having
a relatively high solids content of 75% + 2, dissolved in
n-butanol. Its acid number (mg of KOH/g) is 0~1 max. The
viscosity (poise at 25C) is between 30 and 60. The white
spirit tolerance ~ml/5 g) is between 28 and 60. Its
viscosity allows transport in tank vessels. It has a wide
compatibility range, a high reactivity and good flow
properties.5 Manufacturer: BIP Chemicals Ltdo
Popes Lane Oldbury, Warley West Midlands
B69 4PD
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