Note: Descriptions are shown in the official language in which they were submitted.
2 ~ 7 ~
9~/K 052
Water-thinna~le two-component coating c~mposition
The invention relates to a water-thinnable two-component
coating composition based on polyester resins, to a
process for its preparation and to its use as a coating.
The switch from conventional coatings to water-thinnable
systems is proceeding at full pace. In one-component
systems, in particular, the replacement of conventional
binders by aqueous binders has already reached an
advanced stage.
What is proving difficult is the use of conventional
binders in high-quality two-component systems. Especially
in the case of chemically crosslinking polyurethane
coatings, which due to their outstanding properties are
of great importance in the coatings sector, it has so far
not been possible to dispense with organic solvents. The
use of aqueous binders appeared problematic in that the
polyisocyanate compounds employed as curing agents react
with water with the formation of N-substituted polyurea
compounds and the elimination o~ carbon dioxlde.
It is known from EP 0 358 979 that specific polyhydroxy
polyacrylates are capable of emulsifying polyisocyanate
curing agen-ts in water and curing to give crosslinking
films.
EP 0 469 38~ describes a two-component coating composi-
tion comprising an a~ueous dispersion of a polyurethane
and a water-dispersible polyisocyanate, which cures at
room temperature.
Surprisingly, it has now been found that selected water-
thinnable polyester resins described in greater detail
:
., , : ., :
, , . . , , - . , : . , : .
.:, , .: : :
~ ' ' ' ~ , ,
- 2 _ 2 ~ 7 ~
below are particularly favorable for combining unblocked
polyisocyanate curing agents, having an excellent
emulsifier effect for them.
The invention therefore provides a water-thinnable two-
component coating composition comprising
1) a polyisocyanate component composed of one or more
organic polyisocyanates, and
2) a polyester resin which is composed of the starting
components (a), (b), (c), (d) and (e) or their
ester-forming derivatives, the sum of the r~actants
being 100 mol% and the ratio of the sum of the
hydroxyl equivalents to the sum of the carboxyl
equivalents in the reactants being between 1~0.5 and
1.2Ø
The polyester resin is composed of
(a) at least one dicarboxylic acid that is not a
sulfo monomer,
(b) 0 to 15 mol~, preferably l to 6 mol%, of at
least one difunctional sulfo or phosphono
monomer, whose functional groups are carboxyl
and/or hydroxyl groups, with at least one
sulfonate or phosphonate group,
(c) at least one glycol,
(d) 0 to 40 mol%, preferably 8 to 20 mol~, of a
higher-functional compound (functionality ~2),
whose ~unctiona:L groups are hydroxyl and/or
carboxyl group~, and
(e) 0 to 20 mol% of a mono-functional aarboxylic
acid.
In this polyester resin the quantity of free hydroxyl
groups is between 30 and 350 millie~uival~nts of
OH/100 g, preferably between 100 and 253 meq of OH/100 g,
~ and the content of free neutralized and/or neutralizable
: acid groups, in particular sulfonic, phosphonic and
carboxylic acid groups, is between 5 and 350 meq/100 g~
preferably between 10 and 120 m~q/100 g.
' ' ~ ,
_ 3 _ 2 ~ 7 ~
The in~ention further relates to a process ~or the
preparation of this coating composition and to its use as
a coating.
The polyisocyanate component 1) is any desired organic
polyisocyanate, preferably a diisocyanate having aliphat-
ically, cycloaliphatically, araliphatically and/or
aromatically attached free isocyanate groups which is
liquid at room temperatureO The polyisocyanate component
1~ generally has a viscos.ity of 50 to 20,000 mPa.s at
23C. It is particularly preferably a polyisocyanate or
polyisocyanate mixture containing only a].ipha-tically
and/or cycloaliphatically attached isocyanate group~ and
having an (average) NCO functionality of between 2~0 and
$Ø
The polyisocyanate~ may if required be used as a mixture
with small amounts o~ inert solvents, in order to reduce
the viscosity tQ a value within the stated ranges.
~owever, the amount of such solvents is preferably
calculated so that, in the coatings according to the
invention which are ultimately obtained, not more than
30~ by weight of solvent is present, the calculation
including the solvent which may still be present in the
: polyester resin dispersions or solutions. Examples vf
suitable solvents for the polyisocyanates are aromatic
hydrocarbons, such as solvent naphtha or other solvents,
such as butylglycol, N methylpyrrolidone, methoxy-
: propanol, isopropanol, butanol and acetone.
The polyisocyanates, preferably diisocyanates, arecompounds known in the polyurethane or coatings sector,
such as aliphatic, cycloaliphatic or aromatic diiso-
cyanates. They are preferably of the ~ormula Q(NCO~2,
where Q is a hydrocarbon radical having 4 to 40 carbon
atoms, in particular 4 to 20 carbon atoms, and is prefer-
ably an aliphatic hydrocarbon radical having 4 to 12
carbon atoms, a cycloaliphatic hydrocarbon radical having
` 6 to 15 carbon atoms, an aromatic hydrocarbon radical
- . . . . - . . .
': ,
: , ,
, , : , : ': : ':'' ' , ' ' '
- -
. .
_ 4 _ 2~ 7i~
having 6 to 15 carbon atoms or an araliphatic hydrocarbonradical having 7 to 15 carbon atoms. Examples of such
diisocyanates to be employed with preference are tetra-
methylene diisocyanate, hexamethylene diisocyanate,
dodecamethylene diisocyanate, 1,4-diisocyanatocyclo-
hexane, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl
isocyanate (isophorone diisocyanate), 4,4'-diisocyanato-
dicyclohexylmethane, 4,4'-diisocyanato-2,2-dicyclo-
hexylpropane, 1,4-diisocyanatobenzene, 2,4- or 2,6-diiso-
cyanatotoluene or mixtures of these isomers, 4,4'- or
2,4'-diisocyanatodiphenylmethane, 4,4'-diisocyanato-
2,2-diphenylpropane, p-xylylene diisocyanate and
a,a,a',a'-tetramethyl-m- or -p-xylylene diisocyanate, or
mixtures composed of these compounds.
In addition to these simple polyisocyanates those con-
taining heteroatoms in the radical linking the isocyanate
groups are also suitable. Examples of these polyiso-
cyanates are those containing carbodiimide groups,
allophanate groups, isocyanurate groups, urethane groups,
acylated urea yroups or biuret groups. With regard to
further suitable polyisocyanates, reference is made by
; way of example to German Offenlegungsschrift 29 28 552.
Highly suitable examples are coating-grade polyiso-
cyanates based on hexamethylene diisocyanate or on
3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate
- (IPDI) and/or bis(isocyanatocyclohexyl)methane, in
particular those based exclusively on hexamethylene
diisocyanate. Coating-grade polyisocyanates based on
these diisocyanates are to be understood as meaning the
derivatives of these diisocyanates which have biuret,
urethane, uretdione and/or isocyanurate groups and are
known per se, which after their preparation have, if
required, been freed in a known manner, preferably by
distillation, from excess starting diisocyanate down to
a residual content of less than 0.5% by weight. The
preferred aliphatic polyisocyanates to be used in
accordance wlth the invention include the polyisocyanates
.
_ 5 ~ 7S
which are based on hexamethylene diisocyanate, fulfill
the abovementioned criteria and contain biuret groups, as
can be obtained by, for example, the processes of
US Patents 3,124,605, 3,358,010, 3,903,126, 3,903,127 or
3,976,622 and which comprise mixtures of
N,N,N--tris(6-isocyanatohexyl~biuret w.ith minor amounts of
its high~r homologs, and the cyclic trimers o~
hexamethylene diisocyanate which fulfill the above
criteria, as can be obtained in accordance with
US-A-4,324,879, which essentially consist of N,N,N-tris-
(6-isocyanatohexyl) isocyanurate in a mixture with minor
amounts o-f its higher homologs. Of particular preference
are mixtures of poly.isocyanates based on hexamethylene
diisocyanate which contain uretdione and/or isocyanurate
groups and which fulfill the above criteria, as are
formed by the catalytic oligomerization of hexamethylene
diisocyanate using trialkyl phosphanes. The last-
mentioned mixtures particularly preferably have a
viscosity of 50 to 20,000 mPa.s at 23C and an NCO
functionality of between 2.0 and 5Ø
Also suitable are hydrophilic polyisocyanates which are
stabilized in the aqueous phase by a sufficient number of
anionic groups and/or by te.rminal or lateral polyether
: chains, as are described in EP 0 469 389, EP 0 061 628
and EP 0 206 059.
The aromatic polyisocyanates which are also suitable in
accordance with the invention but are less preferrecl are
in particular coating-grade polyisocyanatss based on
2,4-diisocyanatoto}uene or technical-grade mixtures
thereof with ~,6-diisocyanatotoluene or based on
4,4'-diisocyanatodiphenylmethane or its mixtures with its
isomers and/or higher homologs. Examples of aromatic
: coating polyisocyanates of this type are the isocyanates
containin~ urethane groups, as are obtained by reaction
o~ excess amounts of 2,4~diisocyanatotoluene with
polyhydric alcohols such as trimethylolpropane and the
possible subsequent distillative removal of the unreacted
..
- , . ~ ..
. .
: :. .: . . . . . :.. - . . :
: .: . . . : :: . . : . . . , :
:: . . .: . , : .
, .:: ,. ~ -
- : . . ,
: . -
- 6 - 2~187~
diisocyanate excess. Examples of further aromatic coating
polyisocyanates are the trimers of the monomeric diiso-
cyanates mentioned by way of example, i.e. the
corresponding isocyanato-isocyanu.rates which, following
their preparation, may have been freed from excess
monomeric diisocyanates, pre~erably by distillation.
It is o~ course also possible in principle to use unmodi-
fied polyisocyanates of the type men-tioned by way of
example, provided they conform to the statement~ made
regarding viscosity.
The polyisocyanate component 11 can also comprise any
desired mixtures of the polyisocyanates mentioned.
The polyester resin (2) is, as described above, composed
of the starting components (a), (b), (c), (d) and (e) or
their ester-forming derivatives.
The terms higher-functional, multifunctional or poly-
~unctional as used herein refer to compounds having more
than two re~ctive hydroxyl and/or carboxyl group~; the
term glycol refers to a compound having two and the term
:20 polyol to a compound having more than two hydroxyl
substituents.
.
The dicarboxylic acid aomponent (a) of the polyester
comprises axomatic, cycloaliphatic or aliphatic saturated
or unsaturated dicarboxylic acids and dimeric fatty acids
or mixtures of two or more of these dicarboxylic acidsO
:Examples of these dicarboxylic acids are oxalic, malonic,
glutaricl adipic, pimelic, azelaic, sebacic, fumaric,
maleic and intaconic acid, 1,3-cyclopentanedicarboxylic
acid, l,2-cyclohexanedicarboxylic acid, 1,3-cyclohexane-
:30 dicarboxylic acid, 1~4-cyclohexanedicarboxylic acid,
phthalic, terephthalic and isophthalic acid,
2,5-norbornanedicarboxylic acid, 1,4-naphthalenedi-
carboxylic acid, biphenyldicarboxylic acid,
4,4'-sulfonyldibenzoic acid and 2,5-naphthalene-
.
.
.
. . .
- , ...... . .
.
. . , . . -
. .
..
..
.
2 ~ 7 ~
dicarboxylic acid, and their esters and anhydrides~
Preferred dicarboxylic acid components (a) are phthalic,
isophthalic and terephthalic acid, phthalic anhydride,
adipic acid, succinic acid and its anhydride, dimeric
fatty acids, sebacic and azelaic acid, 1,3 cyclohexanedi-
carboxylic acid and glutaric acid and esters thereof~
Component (b) of the polyPster is a difunctional
aroma-tic, cycloaliphati~ or aliphatic compound having
reactive carboxyl and/or hydroxyl groups which also has
a group -S03x- or -P(O)(OX)2-, where X is hydrogen or a
metal ion such as Na+, Li+, X+, Mg~+, Ca2+, Cu2+ or a
nitrogen-containing cation of aliphatic, cycloaliphatic
or aromatic compounds`, such as ammonia, triethylamine,
dimethylethanolamine, diethanolamine, triethanolamine and
pyridine.
The groups -S03X- or -P(O)(OX)2- can be attached to an
aromatic nucleus such as phenyl, naphthyl, biphenylyl
nucleus, methylenediphenyl or anthracenyl. Hydroxy- and
carboxyarylsulfonic acids are preferredO
Examples of component (b) are sulfoisophthalic acid,
sul~oterephthalic acid, sulfophthalic acid, sulfo-
salicylic acid, sulfosuccinic acid and esters thereof.
Particular pre~erence is given to the Na salts of
sul~oisophthalic acid, sul~oisophthalic acid dimethyl
ester, sulfosalicylic acid and sulfosuccinic acid.
The proportion of component (b) i9 0 to 15 mol%, particu-
larly preferably up to 6 mol%.
The glycol component (c) may comprise low molecular
weight aliphatic, cycloaliphatic or aromatic glycols,
polyhydroxy polyethers or polycarbonate-polyols. Examples
of low moleculax weight glycols are ethylene glycol,
1,2-propanediol, 1,3-propanediol, 2~2-dimethyl-
1,3-propanediol, 1,3-buthnediol, 1,4-butanediol,
, .
- . . . ..
. - . : , . ~ , . :
.. . . ..
.
,, ':, ,:,' ' .
.. . .. . . . .
~ 2 ~ 7 ~
1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-
1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclo-
hexanedimethanol, 1,4-cyclohexanedimethanol, perhydro-
bisphenol A and p-xylylenediol, and 2-ethyl-2-butyl-
propanediol.
Suitable polyhydroxy polyethers are compounds of the
formula
H- [ ~O~ ( CHR ) n~ 3 mOH
in which0 R is hydrogen or a low alkyl radical which may have
various substituents~
n is a number from 2 to 6 and
m i5 a number from 6 to 120.
Examples are poly(oxytetxamethylene) glycols, poly~oxy-
ethylene) glycols and poly(oxypropylene) glycols. The
preferred polyhydroxy polyet,hers are poly(oxypropylene)
glycols having a molecular weight in the range from 400
to 5000.
The polycarbonate-polyols or polycarbonate-diols are
compounds of the formula
o
11
~O-R-(O-C-O-R-)n-OH
in which R is an alkylene radical. These O~-~unctional
polycarbonates can be prepared by reacting polyols ~uch
~ as propane-1,3-diol, butane-1,4-diol, hexane-1,6-diol,
; diethylene glycol, triethyIene glycol, 1,4-bishydroxy-
methylcyclohexane, 2,2-bis(4-hydroxycyclohexyl)propane,
neopentylglycol, trimethylolpropane and pentaerythritol
with dicarbonates such as dimethyl, diethyl or diphenyl
carbonate or pho~gene. Mixture~ of these polyols can also
; be employed.
~he proportion of component ~c) should be calculated so
.
.
,
,
,
,
' ' ,
2 ~ 7 i)
as to eonform to the ratio o-f hydroxyl equivalents to
carboxyl equivalents which was indicated initially.
The higher-functional component (d) which preferably
contains 3 to 6 hydroxyl and/or carboxyl groups preEer-
ably comprises trimethylolpropane, trimethylolethane,glycerol, ditrimethylolpropane, pentaerythritol, dipenta-
erythritol, bishydroxyalkanecarboxylic acids, such as
dimethylolpropionic acid, trimellitic anhydride and
polyanhydrides as deseribed in DE 28 11 913 or mixtures
of two or more of these compounds, the propor-tion of the
higher-functional component (d) being preferably 5 to
30 mol%, in particular 8 to 20 mol%.
The monofunctional carboxylic acids (e) are primarily
fatty aeids such as eapric aeid, lauric acid, stearic
aeid and palmitie acid, but it is also possible to employ
branched carboxylie aeids, sueh as isovalerie aeid and
isooetanoie aeid.
The number-average molecular weight of the polyester
resin, determined experimentally using gel permeation
chromatography, may lie between 500 and 4000, and is
preferably from 1000 to 3500.
The glass transition temperature of the polyesters is
preferably between -60C and 100C.
In order, if desired, to achieve as far as possible a
quantitative cocondensation of the sulfo or phosphono
monomer, it may be neeessary to carry out the synthesis
of the deseribed polyesters in a multistage proeess. For
this purpose all of the hydroxy funetional eomponents are
initially reacted in the presence of catalysts with the
sulfo or phosphono monomers and, i~ appropriate, with
carboxylic acid-containing eomponents in sueh a way that,
in the eondensation, 95% of the quantity of distillate
ealeulated for quantitative eonversion i5 obtained. The
aliphatie earboxylie aeid eomponents, if appropriate, are
'. ,~
'.
,
2~0~ ~7 ~
- 10 -
then reacted, the condensation being continued up to the
desired content of carboxylic acid equivalentsO
When using a bishydroxyalkanecarboxylic acid, an OH-func-
tional polyester is Eirst prepared which is then sub
jected to a condensation reaction with the bishydroxy-
alkanecarboxylic acid and a further dicarboxylic acid to
give the desired polyester.
If polycarboxylic anhydrides are used to introduce the
anionic groups, then an O~-functional polyester is
reacted with the anhydride to give the half-ester, and
condensation is then continued up to the desired acid
number.
The reaction takes place at temperatures between 140C
and 240C, preferakly between 160C and 220C. To avoid
losses of glycol, the condensate is distilled using a
distillation column. Suitable catalysts are preferably
organometallic compounds, in particular compounds con-
taining zinc, tin or titanium, for example zinc acetate,
dibutyltin oxide or tetrabutyl titanate. The amount of
catalyst is preferably 0.1 to 1.5% by weight of the totll
batch amount.
The acid groups can be introduced via the individual
components into the polyester already in neutralized
form; where free acid groups ars present in the poly-
ester, they can if desired be neutralized with aqueoussolutions of alkali metal hydroxides or with amines, for
example with trimethylamine, triethylamine, dimethyl-
aniline, diethylaniline, triphenylamine, dimethylethanol-
amine, aminomethylpropanol, dimethylisopropanolamine or
; 30 with ammonia.
The polyester can be isolated in bulk, but it is pre~er-
able to prepare a 50 to 95% solution in a water-miscible
organic solventO Suitable solvents in this respect are
preferably oxygenated solvents such as alcohols, ketones,
: .
,
.
2 1 ~
esters and ethers, for example ethanol, n-propanol,
isopropanol, isobutanol, butyl acetate and butylglycol,
or nitrogen-containing solvents such as N-methylpyrrol-
idone. The viscosity of these solutions is preferably
between 0.5 and 40 Pa.s at 60C.
This solution is then used to prepare the polyester
dispersion, so that amounts of 15 to 65% by weight of
polyester, O to 30% by weight of organic solvents and
35 to 85~ by weight of water are present in the disper-
sions. The resulting pH is 2 to 8.5, preferably 4.0
to 8Ø
The content of polyester res.in in the aqueous coating
composition is .in general 5 to 40% by weight, preferably
15 to 30% by weight, based on the overall aqueous coating
composition.
In addition to the polyester resin, the aqueous coating
composition can also contain, as binders, up to 60% by
weight, preferably up to 30% by weight, based on the
polyester resin, of other oligomeric or polymeric
materials, such as cro slinkin~, water-soluble or water-
dispersible phenolic resins, polyurethane resins, epoxy
~ resins or acrylic resins, etc., as described for example
in European Offenlegungsschrift 89 497.
To prepare the ready~to-use coatings the polyisocyanate
component 1) is emulsified in the aqueous
dispersion/solution o-E the polyester resin 2), the
dissolved or dispersed polyester resin adopt.ing the
function of an emulsifier for the added polyisocyanate.
This is krue in particular for the preferred case in
which polyisocyanates are used which are not hydrophilic-
ally modified. It is also possible to use as polyiso-
cyanate component 1) hydrophilic-modified polyisocyanates
which, due to the incorporated ionic or nonionic
hydrophilic centres, are autodispersible.
. . . .
. ~
- 12 ~ 7~
Mixing can be carried out by simply stirring the com
ponents together at room temperature. The amount of
polyisocyanate component is preferably calculated so as
to result in an NCO/OH equivalen-t ratio, based on the
isocyanate groups of component 1) and the alcoholic
hydroxyl groups of component 2), of 0.5:1 to 5:1, in
particular 0.8:1 to 3:1.
Prior to the addition of the polyisocyanate component,
the auxiliaries and additives customary in coatings
technology can be incorporated into the polyester
resin 2), i.e. the dispersion or solution of the
polymers. These include for example antifoams, leveling
assistants, pigments and pigment dispersants.
The resulting coatings according to the invention are
suitable ~or practically all areas of application which
currently employ solvent-corltaining, solvent-free or
other types of aqu00us paint and coating sy~tems having
an enhanced range of properties.
They are preferably used for topcoats and one-coat
finishes, in which case the substrates to be coated may
be, for example, metal, mineral construction materials
such as limestone, cement or gypsum, fiber-ceme~t
construction materials, concrete, wood or timber
materials, paper, asphalt, bitumen, plastics of various
kinds, textiles or leather. The metallic substrates are
preferably in all cases automobiles.
Another pre~erred use is as a primer or sur~acer, in
which case the substrates to be coated may be, ~or
example, metal, mineral construction materials such as
limestone, cement or gypsum, fiber-cement construction
materials, concrete, wood or timber materials, paper,
asphalt, bitumen, textiles or leather~ The metallic
substrates are again preferably automobiles.
2 ~ 7 ~
13 -
~xamples:
The polyester synthesis is carried out in a 4 l four-neck
flask ~itted with a packed column (column tube: 30 mm
diameter, 2000 mm length; packing: glass rings of 6 mm
diameter and 6 mm length) and a descending bridge-shaped
distillation head, with temperature sensing of the
reacting material under a protective gas atmosphere
(protective gas feed, nitrogen). I~ low-boiling alcohols,
especially methanol, are distilled off a~ condensate, the
receiver should be cooled using an ice bath The
abbreviations used below are explained on page 17.
Polyester 1
Initial amounts as in Table 1
Melt neopentylglycol and trimethylolpropane, add IPA and
1.5 g of dibutyltin oxide, heat so that the overhead
temperature does not exceed 100C, subject the mixture to
condensation at 190C to 200C until the content of acid
groups is 10 meq of COOH/100 g.
Cool to 140C, add ADPA and DMPA, heat so that the
overhead -temperature does not exceed 100~C, subiect the
mixture to condensation at temperatures of up to 200C
until a value of 64 meq of COOH/100 g is reached. ~hen
cool to 80C, add 62.2 g of dimethylethanolamine and
~:~ 290 g of N-methylpyrrolidone and di~perse in 2818 g of
wat~r.
Polyester 2
Initial amounts as in Tabl.e 1
Melt the hydroxyl group-containing reactants, add
5-SIP-~a, TPA and 1~5 g of dibutyltin oxide, heat so that
the overhead temperature does not exceed 100C, subject
the mixture to condensation at 185C to 195C until 135 g
of distillate are obtainedO
Cool to 120C, add IPA and 1.0 g of dibutyltin oxide,
heat so that the overhead temperature does not exceed
100C, subject the mixture to condensation at temper-
.
''
2~0~l87~
- 14 -
atures of up to 190C until the content of free carboxyl
groups is 55 meq of COOH/100 g, then continue
condensation a-t 180C to 200C and 100 mbar until a value
of 7 meq of COOH/100 g is reached.
720 g of N-methylpyrrolidone are added at 140C and the
batch is then dispersed with 4680 g of water.
Polye~ter 3
Initial amounts as in Table 1
Melt neopentylglycol and trimethylolpropane, add TPA, IPA
and 1 5 g o~ dibutyltin oxide, heat 50 that the overhead
tempexature does not exceed 100C, subject the mixture to
condensation at 190C~to 200C until the content of acid
~roups is 10 meq of COOH/100 g.
Cool to 140C, add TMA~ and stir at this temperature
15 until a value of 71 meq of COOH/100 g is reached. ~hen
cool to 80C, add 175 g of N-methylpyrrolidone and 80 g
of dimethylethanolamine, and disperse in 1800 g of water.
Polyester 4
Initial amounts as in Table 1
Melt neopentylglycol and trimethylolpropane, add TPA,
IPA, LA and 2.5 g of dibutyltin oxide, heat so that the
overhead temperature does not exceed 100C, subject the
mixture to condensation at 190C to 200C until the
content of acid groups i9 10 meq of COO~/100 g.
Cool to 140C/ add ADPA and DMPA, heat so that the
overhead temperature does no~ exceed 100C, subject the
mixture to condensation at temperatures o up to 200C
until a value of 56 me~ of COO~/100 g is reached. Than
cool to 80C, add 300 g of ~-methylpyrrolidone and 70 g
of dime-thylethanolamine, and disperse in 2430 g of water.
Table 1 (* see over)
,~
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O ~ C~ D
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r~ n ~ ~, o
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r C~ ~ rr
;
n Y) U ~ O In O ~9 ~D
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o ~ o
o
1 w
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;~ ~ $
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- 17 -
Rey. IPA = isophthalic acid
TPA = terephthalic acid
ADPA = adipic acid
5-SIP-Na = 5-sulfoisophthalic acid
Na salt
NPG = neopentylglycol
TMP = trimethylol]propane
DMPA = dimethylolp.ropionic acid
EG = ethylene glycol
LA = lauric acid
TMAA = trimellitic anhydride
PEG = polyethylene ~lycol
2-Component primer
The dispersion batch is prepared by mixing 65.8 part~ by
weight of the polyester (1), (2), (3) or (4) having a
solids content of 38~ by wei~ht with 0.2 part by weight
of a commercially available silicone~free antifoam
(Additol VXW 4973 from Hoechst AG), 0.3 part by weight oE
a commercially available wetting and dispersing auxiliary
(Additol XL 250 from Hoechst AG) and 0.4 part by weight
of a commercially available leveling agent (Additol
; XW 390 from Hoechst AG~o After simply stirring,
14.0 parts by weight of titanium dioxide (Kronos 2310
from Kronos~Titan GmbH), 11.0 partR by weight of a barium
sulfate (Blanc fixe micro from Sachtleben GmbH),
3.7 parts by weight o-f a talc (Naintsch E 7 from Naintsch
Mineralwerke Gmb~) and 0.1 part by weight of a carbon
black (Flammru~ 101 from Degussa AG) are added to the
batch, which is dispersed for about 30 m:inutes in a
dissolver at a speed of 6000 rpm.
A variety of polyisocyanates can be employed as the
curing component, for example (I) ~asonat FDS 342~ ~rom
:BA5F AG, (II) Desmodur VPhS 2550, lIII) Desmodur N 3300
and (IV) Desmodur N 100 from Bayer AG.
The dispersion batch was then mixed with 12.5 parts by
weight o~ a suitable polyisocyanate which has, if
~:~
:, ' . . ~ . '
2 ~ 7 ~
- 18 -
appropriate, been previously diluted with methoxypropyl
acetate; the composition of the batch in accordance with
the invention is as follows:
. . .
Example A Example B Example C ~xample D
_
Binder 1 2 3 4
25.00 25.00 .~5.00 25.0~
Pigments 28.80 28.80 28.80 28.80
Auxiliaries0.~0 0.90 0.90 0.90
Total solids54.7054~70 54.70 54.70
Deionized waker 42.05 40.05 42.05 42.05
Organic solvent 3.25 5.25 3.25 3.25
Total 100~00 100.00 100.00 100.00
_ _ __ _
Polyisocyanate (III) 12.50 ~I) 12.50 (II) 12.50 (III) 12.50
Methoxypropyl
': acetate6.25 0.00 0.00 12.50
~ _
The ready-to-process batches have a con-tent of organic
solvents of only 2.89 to 12.60~ by weight. The coatings
are applied to the substrate at a wek-~ilm thickness of
150 300 ~m ~corresponding to a dry-film thickness of
25 ko 50 ym) and dried for 30 minutes ak 80C in a
circulating-air oven.
The cured coating ~ilms of Examples A to D can be charac-
terized as fo1lows:
~, :
, -
: . . , ., .. ; . . . ~
: , . . ~ . . : .. , .. , ~ : :
- , . ... .
.. : . . : . ~ ... :
' - : .. ' ' : . ' '
.
8 ~ ~;
- 19 -
Solvent resistance Example A Example B Example C Example D
_ ____
Isopropanol good-moderate very good m~derate ~sderate
Isopropanol/water (1:1) gcod very good moderate ~Lderate
Ethanol very good- ve~y good- moderate moderate good good
Ethanol/water (1:1) good very good mLderate moderate
Pre~iumrgrade gasolLne good moderate moderate n~derate
Example A ~ le B Exa~ple C ~xample D
_
Pendulum hardness 75"-100" 100"-110" 25"-40" 15"-25
acc. to DIM 53157
60 ~los~ 50% 43~ 88% 73
acc. to DIN 67530
Hot-wet
test acc. to good-moderate good-~oderate good moderate
DIN 50017 SK
Sal~ spra~ test good very good- ~ery good- very good-
acc. to ASTM~B117-6~ good good good
Topcoat appeaLance good good very good good
Sto~e chip:
topcoat adhesion good good go,od-mcderate very good
penetrations good ~x~derate good very good
_
2-Component topcoat
The dispersion batch is prepared by mixing 71.1 parts by
weight of polyester (1) or ~4) having a solids content of
38% by ~eight with 0O2 part by weight of a commercially
available silicone-free antifoam (Additol VXW 4973 from
Hoechst AG), 0.3 part by weight of a commercially
available wetting and dispersing auxiliary ~Additol
XL 250 from ~oechst AG) and 0.4 part ~y weight of a
commeFcially available leveling agent ~Additol XW 390
.
.
,: ' ', .
. '. : , . ~ . :
.
20 -
from Hoechs-t AG). After the simple stirring o the
additives together with one another, 24.6 parts by weight
o~ titanium dioxide (Kronos 2310 from Kronos-Titan GmbH)
are added to the batch, which is dispersed for about 30
minutes in a dissolver at a speed of 6000 rpm.
A variety of polyisocyanates can be employed as the
curing component, for example lI) Basonat FDS 3425 from
BASF AG, (II~ Desmodur VPLS 2550, (III~ Desmodur N 3300
and (IV) Desmodur N 100 from Bayer AG.
The dispersion batch was then mixed with 13.4 parts ~y
weight of a suitable polyisocyanate which is, if appro-
priate, previously ~i;luted with methoxypropyl acetate;
the composition of the batch in accordance with the
invention i~ as ~ollows:
_
Example A Example B Example C Example D
Binder 1 2 3 4
25.00 25.00 25.00 25~00
Pigments 28.80 28.80 28.80 28.80
Auxiliari~s 0.90 0.90 0.90 0.90
Total solids54.70 54.70 54.70 54.70
Deionized water42.05 40.05 42.05 42.05
Organic solvent3.25 5.25 3.25 3.25
__ .
Total 100.00 100.00 100.00 100.00
_ .
Polyisocyanate (III) 12.50 ~I) 12.50 ~II) 12.50 (III) 12.50
Methoxypropyl :
acetate 6.25 0.~0 n.oo 12.50
.
'
,, , : . - .,
.
.
,
2 ~ 7 ~ `
~ 2~ -
The ready-to-procPss batches have a content of organic
solvents of only 8.5 to 13.3% by weight. The coatings are
applied to the substrate at a wet-film thicknes~ of
200-400 ~m (corresponding to a dry-film thickness of
30 to 60 ~m) and dried for 30 minutes at 80C in a
circulating-air oven.
The cured coating films of Examples E and F can be
characterized as follows:
Solvent resistance Example E Example F
.
Isopropanol very good very good-good
Isopropanol/water ~1:1) very good very good-good
Ethanol very good-good good
Ethanol/water (1:1) very good good
Premium-grade gasoline very good-good good-mod~rate
Example E Example F .
.
Pendulum hardness about 115" about 145"
acc. to DIN 53157 .
60 Gloss about 87% about 87%
acc. to DIN 67530
Topcoat appearance good good
Stone chip:
topcoat adhesion good good
penetrations good very good-goQd
_22_2~8,~
The cured films from all the examples are tested in
accordance with the following test proc~dures:
Pendulum hardness: in accordance with DIN 53 157
Degree of gloss: in accordance with DIN 67 530,
measured at an angle of Ç0
Hot-wet test: in accordance with DIN 50 017 SK.
After 240 hours with atmospheric
humidity of 100% and at a
temperature o~ 40C, bli~tering,
gloss and the quality of the coating
surface were subjectively assessed
according to a rating scale
(1 = ver~ good, 5 = very poor)
Salt spray test. in accordance with ASTM-B 117-69.
After 240 hours in a salt spray
atmosphere, blistering and corrosive
penetration at the predetermined
corrosion points were subjectively
assessed according to a rating scale
(1 = very good, 5 = very poor)
Topcoat appearance: the gloss and surface of the topcoat
were subjectively asses~ed according
to a rating scale (1 = very good,
5 = very poor)
25 Stone chip: The stone-chip resistance was te~ted
using a stone chip testing device in
accordance with the VDA [German
Motor Industry Association]
(model 508 from Erichsen). For these
tests, in each case 1 kg of scrap
steel (angular, ~-5 mm) was
projected under compressed-air
acceleration (2 bar) on to the test
panels. Vsing sample panels, an
assessm~nt was made of the topcoat
adhesion (very good = no abrasion,
very poor = complete del~mination)
and of the penetrations down to the
:,
.
- ,
- ~ - .
.'' ' . : : : . : .
.
: . ' ' ' ' ' ' ' ~:
: . ' ' ., . :
2 ~ 7 ~
- 23 -
metal (very good = no penetrations,
very poor = a large number of
penetrations~.
: :
,.
' , ' ~ ~ ' :
~: ' , .` ~ .:
