Note: Descriptions are shown in the official language in which they were submitted.
CA 02449209 2003-11-26
1
COATING MATERIALS THAT CAN BE CURED THERMALLY AND BY
ACTINIC RADIATION, AND THE USE THEREOF
The present invention relates to novel coating
materials which are curable thermally and with actinic
radiation. The present invention also relates to the
use of the novel coating materials curable thermally
and with actinic radiation for producing single-coat
and multicoat clearcoat systems and color and/or effect
paint systems. The present invention additionally
relates to the use of the novel coating materials
curable thermally and with actinic radiation as
adhesives and sealing compounds for producing adhesive
films and seals.
Color and/or effect coatings of motor vehicle bodies,
especially automobile bodies, nowadays consist
preferably of- a plurality of coating films which are
applied over one another and have different properties.
For example, an electrodeposition~coat (electrocoat) as
primer, a primer-surfaces caat or antistonechip primer,
a basecoat, and a clearcoat are applied in succession
to a substrate. In this system, the electrocoat serves
in particular to protect the sheet metal against
corrosion. By those skilled in the art it is often also
referred to as the primer. The primer-surfaces coat
L
CA 02449209 2003-11-26
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serves to cover unevennesses in the substrate, and
because of its elasticity imparts stonechip resistance.
Where present, the primer-surfacer coat may also serve
to reinforce the hiding power and to deepen the shade
of the paint system. The basecoat .'contributes the
colors and/or optical effects. The clearcoat is used to
intensify ,the optical effects and to protect the paint
system against mechanical and chemical damage. Basecoat
and clearcoat are frequently also referred to
1
collectively as the topcoat. For further details, refer
to Rompp Lexikon Lacke and Druckfarben, Georg Thieme
Verlag, Stuttgart, New York, 1998, pages 99 and 51,
"automotive finishes". In the text below, these
multicoat paint systems are referred to as multicaat
color and/or effect paint systems.
On account of their size and the fact that they almost
always subsequently receive logos, inscriptions and/or
blocks of color or images, commercial vehicles are
frequently provided only with a pigmented coating,
known as a solid-color topcoat.
More recently, the clearcoats in particular have been
produced from clearcoat materials which are curable
thermally and with actinic radiation. Here and below,
actinic radiation means electromagnetic radiation, such
as near infrared, visible light, UV radiation or
x-rays, especially W radiation, and corpuscular
radiation, such as electron beams. Combined curing by
CA 02449209 2003-11-26
.. - 3 -
means of heat and actinic radiation is also referred to
by those skilled in the art as dual cure.
Dual-cure coating materials, especially dual-cure
clearcoat materials, possess the key advantage that,
even in the shadow zones of three-dimensional
substrates of complex shape, such as autobodies,
radiators or electrical wound articles, and even in the
absence of optimum - in particular, complete - exposure
E' 10 of the shadow zones to actinic radiation,, they provide
coatings whose profile of performance properties at
least comes close to that of the coatings outside of
the shadow zones. As a result, the coatings in the
shadow zones are also no longer readily damaged by
mechanical and/or chemical attack, as may occur, for
example, on the production line during the installation
of further components of motor vehicles into the coated
bodies.
Additionally, curing with actinic radiation may
compensate incomplete ,thermal curing, if for example
the dual-cure coating materials cannot be heated to the
temperatures required for rapid progression of the
thermal crosslinking reactions, owing to the
temperature sensitivity of the coated substrates.
Dual-cure coating materials and ,their use to produce
high-quality multicoat color and/or effect paint
systems are known, for example, from the German patent
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- 4 -
applications DE 42 15 070 A1, DE 198 18 735 A1, DE 199
O8 018 A1, DE 199 30 665 A1, DE 199 30 067 A1, DE 1.99
30 664 Al, DE 199 29 674 A1, DE 199 20 799 AI, l99 58
726 A1 or DE 199 61 926 A1 or are described in the
German patent applications DE 100 27 268.1,
DE 100 42152.0, DE 100 47 989.8. or DE 100 55 549.7,
unpublished at the priority date of the present
specification. The use of additives based on a
(meth)acrylate (co)polymer having a number-average
molecular weight of from 5 000 to 100 000 daltons is
not revealed by the patent applications.
The refinishing or repeat finishing of these high-
quality multicoat color and/or effect paint systems
imposes exacting demands on the refinish materials and
the refinish process. This is particularly the case
with the line refinishing of coated autobodies where
the original (OEM) finish requires extensive or
complete recoating (repeat finishing). The colors
and/or optical effects in the refinish must not differ
from those of the original finish. Moreover, the
refinish must adhere firmly to the original finish.
I3owever, where the original finishes are produced. using
the dual-cure clearcoat materials, which have
particular technological advantages, adhesion problems
arise which are attributable to the particularly high
crosslinking density of the radiation-cured systems.
Effective adhesion in such cases is achievable only by
4.
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- 5 -
a physical treatment, such as an ultrasound and/or heat
treatment, a mechanical treatment, by sanding,
polishing and/or buffing, for example, and/or a
chemical treatment, such as incipient etching with
appropriate chemicals, such as acids or bases, and/or
by flaming. These measures may still be feasible in the
refinishing of small .areas; on the industrial scale,
they are completely impracticable because in that
context they are too time-consuming and energy
f
consuming and in many cases give rise to safety
objections. Where the measures are not taken, however,
the repeat coatings and refinishes, particularly in the
case of the following systems:
- clearcoat (original)/clearcoat (refinish), and
- basecoat (original)/clearcoat (original)/basecoat
(refinish)/clearcoat (refinish)
It
tend toward delamination, which with such high-quality
products as motor vehicles is unacceptable. These key
disadvantages are hindering the wide spread..of the
dual-cure coating materials - which are otherwise so
advantageous - within industrial coating.
These problems also arise with the refinishing or
repeat finishing of solid-color topcoats produced from
pigmented coating materials curable thermally and with
actinic radiation.
i.
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6
It is an object of the present invention to.find novel
coating materials curable thermally and with actinic
radiation (dual-cure coating materials) which provide
novel coatings having improved performance properties.
In particular, the novel coatings, as single coats or
as the topmost coat of a multicoat paint system, should
permit extensive refinishing or repeat finishing
without the need to take measures to promote adhesion,
such as the abovementioned physical, mechanical and/or
chemical surface treatments.
The invention accordingly provides the novel coating
materials curable thermally and with actinic radiation,
comprising
(A) at least one binder selected from the group
consisting of random, alternating and block,
linear, branched and comb polyaddition resins,
polycondensatian resins, and addition (co)polymers
of olefinically unsaturated monomers, curable
physically, thermally, with actinic radiation, and
thermally and with actinic radiation;
and
(B) from 0.01 to 3~ by weight,' based on the solids of
the coating material, of at least one additive
based on at least one (meth)acrylate (co)polymer
selected from the group consisting of
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- _ '~
(meth)acrylate .(co)polymers having a number-
average molecular weight of from 4 000 to 100 000
daltons and a low to high polarity.
In~the text below, the novel coating materials curable
thermally and with actinic radiation are referred to as
"coating materials of the invention".
Further subject matter of the invention will emerge
k.
from the description.
In the light of the prior art it was surprising and
unforeseeable for the skilled worker that the object on
which the present invention is based could be achieved
by the, inventive use of the additive (B) . A particular
surprise was that the additive (B), as far as improving
the wettability of the original finishes and the
adhesion between original finish and refinish or repeat
( finish, was extraordinarily effective. even in small
amounts, so that there was no longer any need to
perform adhesion-promoting surface treatment of the
original finishes, such as a physical treatment, by
ultrasound and/or heat, for example, a mechanical
treatment, by sanding, polishing and/or buffing, fvr
example, and/or a chemical treatment, by incipient
etching with appropriate chemicals, such as acids or
bases, for example, and/or by flaming. It was also
surprising that the coatings of the invention had a
significantly reduced sensitivity toward fingerprints,
CA 02449209 2003-11-26
.. _
which greatly facilitated .the .handling of substrates
that had been coated with the coatings of the
invention. Entirely surprising was that the coating .
materials of the invention could also be used as dual
5. cure adhesives and sealing compounds for producing
adhesive films and seals.
The essential constituent of the coating material of
the invention is at least one, especially one, additive
(B) based on at least one, especially one,
(meth)acrylate (co)polymer, particularly a
(meth)acrylate copolymer, selected from the group
consisting of (meth)acrylate (co)polymers With a
number-average molecular. weight of from 4 000 to
100 000, preferably from 4 100 to 90 000, more
preferably from 4 200 to 80 000, ~ with particular
preference from 4 300 to 60 000, with very particular
preference from 4 400 to 50 OOO,~and in particular from
4 500 to 40 000 daltons, and a low to high, in (
particular a low to moderate,~polarity.
In accordance with the invention, the additive (B) is
present in the coating materials of the invention in an
amount, based in each case on the solids of (B), of
from O.Ol to 3%, preferably from 0.02 to 2.8%, more
preferably from 0.03 to 2.6%, with particular
preference from 0.04 to 2.4%, and in particular from
0.05 to 2.2.% by weight:
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_ 9 _
The (meth)acrylate (co)polymer (B) for use in
accordance with the invention may be added as it is to
' the coating materials of the invention. Tt is of
advantage, however, to add the' (meth)acrylate
(co)polymer (B) in the form of an organic solution.
Accordingly, the additive (B) for use in accordance
with the invention preferably comprises at least one
organic solvent. The amount of organic solvent may vary
widely. The solvent content is preferably made such
that the solids content of the additive (B), based on
(B), is from 10 to 80~, more preferably from IS-to 75%,
with particular preference from 20 to 700, with very
particular preference from 25 to 65%, and in particular
from 30 to 60~ by weight.
It is preferred to use organic solvents which do not
inhibit the dual-cure crosslinking of the coating
materials of the invention and/or do not enter into any
( disruptive interactions with constituents of the
coating materials of the invention. The solvents may be
inert or else may participate in the crosslinking
reactions as reactive diluents which can be crosslinked
thermally and/or with actinic radiation. The skilled
worker will therefore select suitable solvents easily
on the basis of their known solvency and their
reactivity. Examples of suitable solvents are known
from D. Stoye and W. Freitag (editors), "Paints,
Coatings and Solvents", second, completely. revised
edition, Wiley-VCFi, Weinheim, New York, 1998, "19.9.
CA 02449209 2003-11-26
R, - 10 -
Solvent Groups", pages.327 to 373.
'The additives (B) are commercial products and are sold,
for example, under the brand name BXK~ 354, 355, 357,
358, 380, 381 or 39Q, especially~358, by Byk Chemie.
The further essential constituent of .the coating
materials of the invention is at least one binder (A).
Binders (A) are selected from the group consisting of
random, alternating and block, linear, branched and
comb 'addition (co)polymers of ethylenically unsaturated
monomers, polyaddition resins .and/or polycondensation
resins curable physically, thermally, or thermally and
with actinic radiation. Regarding these terms, refer to
Rompp Zexikon Zacke and Druckfarben, Georg Thieme
Verlag, Stuttgart, New York, 199$, page' 457,'
"polyaddition" and "polyaddition resins (polyadducts)",
and also pages 463 and 464, "polycondensates",
"polycondensation", and ''polycondensation resins", and
also pages 73 and 74, "binders".
Examples of suitable addition (co)polymers (A) are
(meth) acrylate (co) polymers or partially sapoi~ified
polyvinyl esters., especially (meth)acrylate copolymers.
Examples of suitable polyaddition resins and/or poly-
condensation resins (A) are polyesters, alkyds,
polyurethanes, polylactones, polycarbonates, poly-
CA 02449209 2003-11-26
- I1
ethers, epoxy resin-amine adducts, polyureas, poly-
amides, polyimides, polyester-polyurethanes, polyether-
polyurethanes ox polyester-polyether-polyurethanes,
especially polyesters.
Of these binders (A?, the (meth) acrylate copolymers and
the polyesters, especially the (meth)acrylate
copolymers, have particular advantages and are
therefore used with particular preference.
y
IO
The coating material for use in accordance with the
invention accordingly comp.r.ises at least one,
especially one, (meth)acrylate copolymer (A) as binder.
In some cases. however, it may be advantageous to use
I5 at least two, especially two (meth)acrylate copolymers
(A) which have a different profile of properties in
terms of the preferred ranges of OH number, glass
transitian temperature, and number-average and rnass-
average molecular weight that are indicated below.
The (meth)acrylate copolymer (A) preferably has
- an OH number of from 100 to 220, more preferably
from 130 to 200, with particular preference from
140 to 190, and in particular. from 145 to 180 mg
KOH/g,
- a glass transition temperature of from -35. to
t60°C,,in paxticular from -20 to +40°C,
CA 02449209 2003-11-26
_ 12
- a number-average molecular weight of from 1 000
to 10 000 daltons, in particular from 1 500 to
000 daltons, and
5 - a mass-average molecular weight of from 2 000 to
40 000 daltons, in particular from 3 000 to
20 000 daltons.
The (meth)acrylate copolymer (A) preferably contains an
amount corresponding to its OH number of hydroxyl- (
containing olefinically unsaturated monomers (a) in
copolymerized form, of which
(al) from 20 to 905, preferably from 22 to 85$, more
preferably from 25 to 80°a, arid in particular from
28 to 75~ by weight, based.in each case on the ,
hydroxyl-containing monomers (a), are selected
-from the group consisting of 4-hydroxybutyl
(meth)acrylate and 2-alkylpropane-1,3-diol (
mono(meth)acrylates, and
(a2) from 20 to 80g, preferably from 15 to 78%, more
preferably from 20 to 750, and in particular from
to ?2~ by weight, based in each case on the
25 hydroxyl-containing monomers (a), are selected
from the group consisting of other hydroxyl-
containing olefinically unsaturated monomers.
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- 13
Examples of suitable 2-alkylpropane-1,3-diol mono-
2-eth 1-,
(-meth)acrylates (a1) are 2-methyl-, y
2-propyl-, 2-isopropyl- or 2-n-butylpropane-1,3-diol
mono(meth)acrylate, of which 2-methylpropane-1,3-diol
rnono(meth)acrylate is particularly advantageous and is
used with preference.
Examples of suitable other hydroxyl-containing
olefinically unsaturated monomers.(a2) are hydroxyalkyl
esters of olefinically unsaturated carboxylic, sulfonic
and phosphonic acids and acidic phosphoric and sulfuric
esters, especially carboxylic acids, such as acrylic
acid, beta-carboxyethyl acrylate, methacrylic acid,
ethacrylic acid and crotonic acid, particularly acrylic
acid and methacrylic acid. They are derived from an
alkylene glycol, which is esterified with the acid,' or
are obtainable by reacting the acid-with an alkylene
oxide such as ethylene oxide or propylene oxide . It is
preferred to use the hydroxyalkyl esters in which the
hydroxyalkyl group contains up to 20 carbon 'atoms,
particularly 2-hydroxyethyl or 3-hydroxypropyl acrylate
or methacrylate; 1,4-bis(hydroxymethyl)cyclohexane or
octahydro-4,7-methano-1H-indenedimethanol monoacrylate
or monomethacrylate; or reaction products of cyclic
esters, such as epsilon-caprolactone, for example, and
these hydroxyalkyl esters; or olefinical.ly unsaturated
alcohols such. as allyl alcohol: or polyols, such as
" trimethylolpropane monoallyl or diallyl ether or
pentaerythritol monoallyl, diallyl or triallyl ether.
CA 02449209 2003-11-26
- 14 '
'These monomers (a2}~ of relatively high functionality
are generally used only in mino r amounts. In the
context 'of the present invention, minor amounts of
moriomers (a2) of relatively high functionality are
amounts which do not lead to crosslinking or gelling of
the (meth}acrylate copolymers (A), unless the intention
is that they should be in the form of crosslinked
micro-gel particles.
i
Also suitable as monomers (-a2) are ethoxylated and,/or~
propoxylated allyl alcohol, which is sold by Arco
Chemicals, or 2-hydroxyalkyl a11y1 ethers; especially
2-hydroxyethyl a11y1 ether. . Where used, they are
preferably employed not as sole monomers (a2} but in an
amount of from 0.1 to 10% by weight, based on the
(meth}acrylate copolymer (A).
Also suitable are reaction products of the olefinically
unsaturated acids listed above, especially acrylic acid ;
and/or methacrylic acid, with the glycidyl ester of an
alpha-branched monocarboxylic acid having from 5 to
1$ carbon atoms per molecule, in particular a Versatic~
acid, or, instead of the reaction products, an
equivalent amount of the abovementioned olefinically
unsaturated acids, especially acrylic acid and/or
methacrylic acid, which is then reacted, during or
after the polymerization. reaction, with the glycidyl
ester of an alpha-branched monocarboxylic acid having
from 5 to 18 carbon atoms per molecule, in particular a
CA 02449209 2003-11-26
M _ 15 _
Versatic~ acid (cf. Rompp Lexikon Lacke and
Druckfarben, Georg Thieme Verlag, Stuttgart, New York,
1998, "Versatic~ acids", pages 605 and 605)..
Not least, acryloyloxysilane-containing vinyl monomers
are suitable as monomers (a2), being preparable by
reacting hydroxy-functional silanes with epichloro-
hydrin. and then reacting that reaction product with
(meth)acrylic acid and/or with hydroxyalkyl and/or
hydroxycycloalkyl esters of (meth)acrylic acid and/or
other hydroxyl-containing monomers (a1j and..(a2).
Besides th.e hydroxyl, groups, the (meth)acrylate
copolymers which are curable thermally. and/or with
actinic radiation may contain on average.per molecule
(l) at least one, in particular at least two,
reactive functional groups) which are able to
undergo thermally ,initiated crosslinking
reactions with complementary reactive functional
groups, and/or .
(ii) at least one, in particular at least two,
reactive functional groups) having at least one,
especially one, bond which can be activated with
actinic radiation.
Examples of suitable complementary reactive functional
groups (l) far use in accordance with the invention are
CA 02449209 2003-11-26
., _ Z 6 -
compiled in the following overview. In the overview,
the variable R stands for an acyclic or cyclic
aliphatic radical,. an aromatic radical and/or aromatic-
aliphatic (araliphatic) radical; the variables R' and
R". stand for .identical or different aliphatic radicals
or are linked with one another to form an aliphatic or
heteroaliphatic ring.
Overview: Examples of complementary functional groups
R
(i)
Binder and crosslinking went
or
Crosslinkinq'aqent and binder ,
-SH -C (O).-OH
-NHz ~C (O) -0-C (0) -
-O- ( CO) -NH- ( CO ) -NH2 -NCO
-O- ( CO ) -NHZ -NH-C ( 0 ) -OR
>NH -CHz-OH
--CHZ-0-R ;;
2 0 -NH-CHZ-0-R
-NH-CHI-OH
-N (-CH2-O-R) 2
-NH-C (O) -CH (-C (0) OR) Z
-NH-C (0) -CH (-C (0) OR) (-C (0) -R)
-NH-C (0) -NR'R"
>Si (OR) z
CA 02449209 2003-11-26
." _ 17 _
-CH-CH2
C
~i
C'~. .
-CH-CHi
--C (O) -OH
-CH-~H
z
-C,(O) -N (CH2-CHZ-OH) z
The selection of the respective complementary reactive
functional groups (i) is guided on the one hand by the
consideration that during the preparation of the
binders (A) and during the preparation, the storage,
the application, and the curing.process they should not
enter into any unwanted reactions, in particular no
premature crosslinking, and/or should not disrupt or
inhibit the actinic radiation cure, and secondly by the
temperature range within which crosslinking is to take
place.
Preferably, the complementary reactive functional
groups (i) are selected on the one hand from the group
consisting of thiol, amino, N-methylolamino, N-alkoxy-
CA 02449209 2003-11-26
w ' ' -~ 18
methylamino, imino, carbamate, allophanate and/or
carboxyl groups, and on the other hand from the group
- consisting of anhydride, carboxyl, epoxy, blocked arid
unblocked isocyanate, urethane, alkoxycarbonylamino,
methylol, methylol ether, carbonate, amino and/or beta
hydroxyalkylamide groups.
Self-crosslinking binders (A) contain, in particular,
methylol, methylol ether and/or N-alkoxymethylamino
1
groups ( l ) .
The complementary reactive functional groups (l) may be
introduced into the (meth)acrylate copolymers with the
aid of the olefinically unsaturated monomers (a3)
described below, which contain the reactive functional
groups (l) in question, or by means of polymer-
analogous reactions.
Examples of suitable olefinically unsaturated monomers
(a3) are
(a31) monomers which carry per molecule at least one
amino group, such as
- aminoethyl acrylate, aminoethyl methacrylate,
allylamine or N-methyliminoethyl acrylate;
and/or
CA 02449209 2003-11-26
w _ 19 _
(a32) monomers which carry per molecule at least one
acid group, such as ~ y
- acrylic acid, beta-carboxyethyl acrylate,
methacrylic acid, ethacrylic acid, erotonic
acid, malic acid, fumaric acid or itaconic
acid;
- olefinically unsaturated sulfonic or
phosphonic acids or their partial esters;
- mono(meth)acryloyloxyethyl maleate.,.succinate
or phthalate; or
l5
- vinylbenzoic acid (all isomers), alpha-
methylvinylbenzoic acid (all isomers) or
vinylbenzenesulfonic acid (all isomers).
i . ..
(a33) Monomers' containing epoxide groups, suc°h as the
glycidyl ester of acrylic -acid, methacrylic
acid, ethacrylic acid, crotanic acid, malic
acid, fumaric acid or itaconic acid, or allyl
glycidyl ether. -
One example of introducing reactive functional groups
(i) by way of polymer-analogous reactions is the
reaction of some of the hydroxyl groups present in the
binder (A) with phosgene, to give resins containing
CA 02449209 2003-11-26
- 20 -
chlorofo-rmate groups, and the polymer-analogous
reaction of the chloroformate-functional resins with
ammonia a.nd/or primary and/or secondary amines to give
binders (A) containing carbamate groups. Further
examples of suitable methods of this kind are kriowri
from the patents US 4,758,632 A1, US 4,301,257 A1 and
US 2,979,514 A1. It is possible, moreover, to introduce
carboxyl groups by the polymer-analogous reaction of
some of the hydroxyl groups with carboxylic anhydrides,
(.
such as malic anhydride or phthalic anhydride.
Furthermore, the (meth)acrylate copal.ymers (A) may also
contain at least one olefinieally unsaturated monomer
(a4) which is substantially or entirely free from
reactive functional groups, such as:
Monomers (a41 ) ;
Substantially acid-group-free (meth)acrylic esters such
as (meth)acrylic acid alkyl or cycloalkyl esters having
up to 20 carbon atoms in the alkyl radical, especiall y
methyl, ethyl, n-propyl, n-butyl, sec-butyl, tert-
butyl, hexyl, ethylhexyl, stearyl and lauryl acrylate,
or lauryl methaerylate; cycloaliphatic (meth)acrylic
esters, especially cyclohexyl, isobornyl, dicyclo-
pentadienyl, octahydro-4,7-methano-1H-indenemethanol or
tert-butylcyclohexyl (meth)acrylate; (meth)acrylic acid
oxaalkyl esters or oxacycloalkyl esters such as
ethoxytriglycol (meth)acrylate and methoxyoligoglycol
(meth)acrylate having a molecular weight Mn of
CA 02449209 2003-11-26
21 _ _
preferably 550 or other ethoxylated and/or propoxy-
lated,. hydroxyl-free (meth)acrylic~ acid derivatives
(further examples of suitable monomers (32) of this
kind are known from. the laid-.open specification
DE 196 25 773~A1, column 3 line v65 to column 4
line 20). They may contain minor amounts of (meth)-
acrylic acid alkyl or cycloalkyl esters of higher
functionality, such as ethylene glycol, propylene
glycol, diethylene glycol, di.propylene glycol, butylene
glycol, pentane-1,5-diol, hexane-1,6-diol, octahydro-
4,7-methano-1H-indenedimethanol or cyclohexane-1,2-,
-1, 3- or -1, 9-diol di (meth) acrylate; . trimethylolpropane
di- or tri(meth)acrylate; or pentaerythritol di-, tri-
or tetra(meth)acrylate. In the context of the present
invention, minor amounts of monomers (a41) of higher
functionality are amounts which do not lead to
crosslinking or gelling of the copalymers, except where
the intention is that they should be in the form of
(,. . crosslinked microgel particles.
Monomers (a42):
Vinyl esters of alpha-branched monocarboxylic acids
having from 5 to I8 carbon atoms in the molecule. The
branched monocarboxylic acids may be obtained by
reacting formic acid or carbon monoxide and water with
olefins in the presence of a liquid, strongly acidic
catalyst; the olefins may be cracking products of
paraffinic hydrocarbons, such as mineral oil fractions,
and may include both branched and straight-chain
CA 02449209 2003-11-26
.. _ 22 _
- acyclic and/or cycloaliphatic olefins. The reaction of
such olefins with formic acid or with carbon monoxide
and water produces a mixture of carboxylic acids in
which the carboxyl groups are.located~predominantly on
a quaternary carbon atom, Other olefinic starting
materials are propylene trimer, propylene tetramer, and
diisobutylene, for example. The vinyl esters may,
however, also .be prepared conventionally from the
acids, for example, by reacting the acid with
1D acetylene. Particular preference - owing to their ready
availability - ~is given to using vinyl esters of ,
saturated aliphatic monocarboxylic .acids having from 9
to 11 carbon atoms and being branched on the alpha
carbon atom. Vinyl esters o~ this kind are sold under
the brand name VeoVa~ (cf. also Rompp Lexikon Lacke and
Druckfarben, Georg Thieme Verlag, Stuttgart, New York,
1998, page 598). ,
Monomers (a43) :,
Diarylethylenes, especially those of the general
formula I:
R1R2C=CR3R° ( I ) ,
in which the radicals Rl, R2, R3 and R9, in each case
independently of one another,. stand for hydrogen atoms
or substituted or unsubstituted alkyl, cycloalkyl,
alkylcycloalkyl, cycloalkylalkyl, aryl, alkylaryl,
cycloalkylaryl, arylalkyl, or arylcycloalkyl radicals,
with the proviso that at least two of the variables Rlr
R2, R3 and R4 stand for substituted or unsubstituted
CA 02449209 2003-11-26
- '23 -
aryl, arylalkyl or arylcycloalkyl radicals, especially
substituted or unsubstituted aryl radicals. Examples 'of
suitable alkyl radicals. are methyl, ethyl, propyl,
isopropyl, n-butyl, isobutyl, te~rt-butyl, amyl, hexyl
arid 2-ethylhexyl. Examples of suitable cycloalkyl
radicals are cyclobutyl, cyclopentyl and cycl.ohexyl.
.Examples of suitable alkylcycloalkyl radicals are
methylenecyclohexane, ethylenecyclohexane, and propane-
1,3-diylcyclohexane.. Examples of suitable cycloalkyl-
alkyl .radicals are 2-, 3- or 9-methyl-, -ethyl-,
-propyl- and -butylcyclohex-1-yl. Examples of suitable
aryl radicals are phenyl, naphthyl, and biphenylyl,
preferably phenyl and naphthyl, and especially phenyl.
Examples of suitable alkylaryl radicals are benzyl and
ethylene- or propane-1,3-diylbenzene. Examples of
suitable cycloalkylaryl radicals are' 2-, 3-, and
9-phenylcyclohex-1-yl. Examples of suitable arylalkyl
radicals are 2-, 3- and 4-methyl-, -ethyl-, -propyl-,
and -butylphen-1-yl. Examples of suitable arylcyclo-
alkyl radicals are 2-, 3-, and 4--cyclohexylphen-1-yl.
The aryl radicals R1, R2, R3 a.nd/or R° are preferably
phenyl or naphthyl radicals, especially phenyl
radicals. The substituents that may be present in the
radicals Rs, R2, R3 and/or. R4 are electron-withdrawing
or electron-donating atoms or organic radicals,
especially halogen atoms, nitrile, nitro, partially or
fully halogenated alkyl, cycloalkyl, alkylcycloalkyl,
cycloalkylalkyl, aryl, alkylaryl, cycloalkylaryl,
arylalkyl, and ar.ylcyclo'alkyl radicals; aryloxy,
CA 02449209 2003-11-26
alkyloxy and cycloalkyloxy radicals; and/or arylthio,
alkylthio and -cycloalkylthio radicals. Particularly
.advantageous are , diphenylethylene,
dinaphthaleneethylene, cis- or trans-stilben.e or
5. vinylidenebis(4-nit.rob2nzene), especially diphenyl-
ethylene (DPE), and so are used with preference. In the
context of the present invention the monomers (a43) are
used in order to regulate the copolymerization
advantageously in such a way. that free-radical
copolymerization~in batch mode is also possible, f
Monomers (a49):
Vinylaromatic hydrocarbons such as styrene, vinyl
toluene, diphenylethylene or alpha-alkylstyrenes,
especially alpha-methylstyrene,
Monomers (a45)~:
Nitrites such as acrylonit.rile and/or rnethacrylo-
nitrile.
Monomers (a46) : . .
Vinyl compounds, especially vinyl and/or vinylidene
dihalides such as vinyl chloride, vinyl fluoride,
vinylidene dichloride or ~'vinylidene difluoride;
N-vinylamides such as vinyl-N-methylformamide, N-vinyl-
caprolactam or N-vinylpyrrolidone; 1-vinylimidazole;
vinyl ethers. such as ethyl vinyl ether, n-propyT vinyl
ether, isopropyl vinyl ether, n-butyl vinyl ether,
isobutyl vinyl ether and/or vinylcyclohexyl ether;
CA 02449209 2003-11-26
F"
- 25 -
'and/or vinyl esters such as vinyl acetate, ' vinyl
propionate, vinyl butyxate,_ vinyl pivalate and/or the
vinyl .ester of 2-methyl-2-ethylheptanoic acid. ,
Monomers (a47) : ~ ' .
Allyl compounds, especially allyl ethers 'and allyl
esters such as allyl methyl, ethyl, propyl or butyl
ether or allyl acetate, propionate or butyrate.
(. . . .
Monomers (a98): . .
Polysiloxane macromonomers which have a number-average
molecular weight Mn of from 1 000 to 40 000 and contain
on average from 0.5 to 2.5 ethylenically unsaturated
double bonds per molecule; especially polysiloxane
macromonomers which have a number-average molecular
weight Mn of from 2 000 to 20 000, with particular
preference from 2 500 to 10 000, and in particular from
3 000 to' 7 000, and contain on average per molecule
from 0.5 to , 2.5, preferably from 0.5 to 1.5,
ethylenically unsaturated double bonds, as are
described in DE 38 07 571 A1 on pages 5 to 7, in
DE 37 06 095 A1 in columns 3 to 7, in EP fl 358 153 B1
on pages 3 to 6, in US 9,759,014 A1 in columns 5 to 9,
in DE 99 21 823 A1 or in the international patent
application WO 92122515 on page 12 line l8 to page 18
line 10.
The monomers (a1) and (a2) and also (a3) and/or (a9)
are selected so as. to give the OH numbers and glass
CA 02449209 2003-11-26
- 2~ -
transition temperatures. indicated above. Furthermore,.
the monomers (a~3) containing reactive fuwctional groups
(i) are selected in their nature anal amount such that
they do not inhibit or prevent entirely, the
crosslinking reactions of the hydroxyl groups with the
compounds (C) described below.
Fox adjusting the.glass transition temperatures, the
skilled worker ma.y select the monomers (a) with the
assistance of the following formula of Fox, with which
the glass transition temperatures of poly-
(meth).acrylates may be calculated approximately:
n=x
1lTg = ~ W11/ Tgn; ~a 1Nn = '(
Tg .- glass transition temperature of the poly-
(meth)acrylate:
Wn - weight fraction of the nth monomer;
Tgn - 'glass transition temperature of the homopolymer
of the nth monomer; and
x - number of different monomers.
The preparation of the (meth)acrylate copolymers (A)
preferred for use has no special features in terms of
its process technology but instead takes place with the
aid of the methods of continuous or batchwise, free-
radically initiated copolymerization that are customary
CA 02449209 2003-11-26
_ 27 _
and. known i~n the plastics field, in bulk, solution,
emulsion, miniemulsion . or microemulsion, under
atmospheric pressure. or superatmospheric pressure, in
stirred tanks, autoclaves, tube reactors, loop reactors
or Taylor reactors, at temperatures of preferably~from
'50 to 200°C.
Examples of suitable copolyrnerization processes are
described in the patent applications DE 197 09 465 A1,
DE 197 09 476 A1,. DE 28 98 906 A1, DE 195 24 182 A1,
DE 198 28 742 Al, DE 196 28 193 A1, DE 196 28 142 A1.,
EP 0 f54 783 A1, WO 95/27742, W0 82/02387 and
W0 98/02966. Alternatively, the copolymerization may be
conducted in polyols (thermally curable reactive
diluents) as the reaction medium, as is described, fox
example, in the German ' patent application
DE 298 .50 243 A1.
i. Examples af, suitable free-radical initiators are
dialkyl peroxides, such as di-tert-butyl peroxide ox
dicumyl peroxide; hydroperoxides, such as cumene
hydroperoxide or tent-butyl hydroperaxide; perestexs,
such as tent-butyl perbenzoate, tert-butyl perpivalate,
tert-butyl per-3,5,5-trimethylhexanoate or tert -butyl
per-2-ethylhexanoate; peroxodicarbonates; potassium,
sodium or ammonium peroxodisulfate; azo initiators,
examples being azo dinitriles such as a~obisiso-
butyronitrile; C-C-cleaving initiators such as
benzpinacol silyl ethers; or a combination of a non-
CA 02449209 2003-11-26
w _ 2g _
oxidizing initiator with hydrogen peroxide. Combina-
tions o.f the above-described initiators may also be
used.
Further examples of suitable initiators are described
in the German patent application DE 196 28 142 A1,
page 3 line 49 to page 9 Line 6.
It is preferred to add comparatively large amounts of
free-radical initiator, with the fraction .of ,the
initiator in the reaction mixture,~based in each case
on the overall amount of the monomers (a) and of the
initiator, being with particular preference from 0.2 tc5
20~ by weight, with very particular preference from 0.5
to 15~ by.weight, and in particular from 1.0 to 10% by
weight.
It is also possible to use thiocarbonylthio compounds
or mercaptans such -as dodecyl mercaptan as chain -
transfer agents or molecular weight regulators.
The nature and amount of the (meth)acrylate copolymers
(A) are preferably selected in such a way that,
following their curing,-the coating materials of the -
invention have a storage modulus.E' in the rubber-
elastic range of at least 10''5 Pa and a loss factor
tan8 at 20°C of not more than 0.10, the storage modulus
E' and the loss factor having been measured by dynamic
mechanical thermoanalysis on free films with a
CA 02449209 2003-11-26
29 _
thickness of 90 t 10 um (cf. in this respect the German
patent DE 197 09 467 C2) .
The reactive functional groups (ii) having at least one
bond which can be activated with actinic'radiation may
be present in the (meth)acrylate copolymers (A). Where
the coating materials for use' in accordance with the
invention include no other constituents which can be
cured with actinic radiation, . the (meth)acrylate
r
ZO copolymers. (A) mandatorily contain these groups (ii).
In the context of the present invention, a bond which
can be activated with actinic radiation is a bond
which, on exposure to actinic radiation; becomes
reactive and, together with other activated bonds of
this kind, undergoes polymerisation reactions and/or
crosslinking reactions which proceed~in accordance with
free-radical and/or. ionic mechanisms. Examples of
a. suitable bonds are carbon-hydrogen single bonds or
carbon-carbon, carbon-oxygen, carbon-nitrogen, carbon-
phosphorus or carbon-silicon single bonds or double
bonds. Of these, the carbon-carbon double bonds are
particularly advantageous and are therefore used with
very particular preference in accordance with the
invention. For the sake of brevity, they are referred
to below as "double bonds".
Accordingly, the inventively preferred group (ii)
contains one double bond or two, three or four double
CA 02449209 2003-11-26
. ~ - 30 -
bonds. Where more than one double bond is used, the
double bonds may be conjugated. In accordance with the
invention, however, it is of advantage if. the double
bonds are present in isolation, in particular each
terminally, in the gxoup (~.i)~ in question. It is of
particular advantage in accordance with the invention
to use two double bonds or, in particular, one double.
bond,
The dual-cure binder (A) Contains on average at least
one of the above-described groups (ii) which can be
activated with actinic radiation. This means that the
functionality of w the binder in this respect is
integral, i.e., for example, is equal to two, three,
four,, five or more, or is nonintegral, i.e., is equal
for example to from 2.1 to 10.5 or more.
Where on average per molecule more than one group (ii)~
which can be activated with actinic radiation is
employed, the groups (ii) are structurally different
from one another or of the same structure.
Where they are structurally different from one another,
this means i.n the context of. the present invention that
two, three, four or more, but especially two, groups
(ii) which can be activated with actinic radiation are
used which derive from two, three, four or more, but
especially two, monomer classes.
CA 02449209 2003-11-26
,: _ 33. _
Examples of suitable groups (ii) are (meth.)acrylate,
ethacrylate, crotohate, cinnamate,, vinyl ether, vinyl
ester, dicyclopentadienyl, norbornenyl, isoprenyl, iso-
propenyl, allyl or butenyl groups; dicyclopentadienyl
ether, norbornenyl ether, .isoprenyl ether, isopr,openyl
J
ether, allyl ether or butenyl ether groups: or
~dicyclopentadienyl ester, norbornenyl ester, isoprenyl
ester, isopropenyl ester, allyl ester or butenyl ester
groups, but especially acrylate groups.
The groups (ii) are attached ,to respective parent
structures. of the binders preferably by way of
urethane, urea, allophanate, ester, ether and/or amide
groups, but in particular by way of ester graups.
Normally this is effected by customary and known
polymer-analogous reactions such as, for instance, the
reaction of pendent glycidyl groups with the above-
described olefinic ,unsaturated monomers containin g an
(' acid group, of pendent hydroxyl groups with the halides
of these .monomers, of hydroxyl groups with isocyanates
containing double bonds, such as vinyl isocyanate,
methacryloyl isocyanate and/or 1-(1-isocyanato
1-methylethyl)-3-(1-methylethenyl)benzene (TMx~ from
CYTEC), or of isocyanate groups with the above
described hydroxyl-containing monomers. .
The amount of the binders (A) in the coating materials
of the invention may vary widely and is guided
primarily by tha functionality of the binders (A), on
CA 02449209 2003-11-26
' - .32
the one whand,, and of the compounds (C), present if
desired and described below, on the other. The amount,
based on the solids of the coating material' of the
invention, is preferably from 20 ~ to 99.8$, more.
5. preferably from 25 to 95~, with particular' preference
from 30 to 90~, with very particular preference from 35,
to 85~, and in particular from 40 to 80~ by weight.
Preferably, the coating materials of the invention
further comprise at least one constituent selected fxom
the group consisting of low molecular mass, oligomeric
and polymeric compounds (C) other than the
(meth) acrylate .copolymers . (A) , which contain on average
per molecule
a5
(i) at least one, preferably at least two, of the
above-described reactive functional groups which
are abl a to undergo thermally initiated cross-
linking reactions with complementaryw reactive
functional- groups, especially hydroxyl groups,
and/or
(ii) at least one, preferably at least two, of the
above-described reactive ftanetional groups having
at least one bond which can be activated with
actinic radiation.
Where the above-described (meth)acrylate copolymer (A)
contains none of the above-described, self-crosslinking
CA 02449209 2003-11-26
... . 3 3
reactive functional groups (i), the dual-cure coating
material for use in accordance with the invention
mandatorily comprises at least one, especially one, low
molecular mass, aligpmeric and/or polymeric compound
(C), in particular a low molecular mass or oligomeric
compound (C), which has reactive functional groups (i)
which are able to undergo thermally initiated
crosslinking.reactions with hydroxyl groups. Suitable
compounds (C) of this kind are customary and known
crosslinking agents, such as are known, for example,
from the German patent application DE 199 24 171 A1,
page 7 line 38 to page 8 line 4~ in conjunction with
page 3 line 43 to page 5 line 31. Preference is given
to employing blocked, part-blocked or nonblocked
1S polyisocyanates.
Where the above-described (meth)acrylate copolymer (A)
contains none of. the. above-described reactive
functional groups (ii) having at least one bond which
can be activated with~actinic radiation, the coating
material of the invention mandatorily comprises at
least, one low molecular mass, oligameric and/or
polymeric compound (C) containing at least one,
preferably at least two, .more preferably at least
three, with particular preference at least four, and, in
particular at least 'five, reactive functional graups
(ii) .
CA 02449209 2003-11-26
., . - 3 ~ -
Examples of suitable low molecular mass, oligomeric.
and/or polymeric compounds.(C) containing at least one
group (ii) are. described in detail in Rompp Lexikon.
Lacke and Druckfarben, Georg Thieme Verlag,.Stuttgart,
New York, 1998, "reactive diluents", pages 491'and 492,
in the German patent application DE 199 OS 013 A1,
column 6 line 63 to column 8 line 65, in the German
patent application DE 199 08 018 A1, page 11 lines 31
to 33, in the German patent application
a
DE 198 18 735 Al,~column 7 lines 1 to 35, or in the
German patent DE 197 09 467 C1, page 4- line 36 to
page 5 line 56. Preference is given to using
pentaerythritol tetxaacrylate, dipentaerythritol
pentaacrylate, and/or aliphatic urethane acrylates
containing six acrylate groups in the molecule.
Instead of or in addition to the compounds (C)
described above, the coating materials of the invention
may .contain at least one, in. particular at least two,
low molecular mass, oligomeric and/or polymeric
compounds) (C) containing at least one,.especially at
least two, groups) _(i) and at least one, in particular
at least two, groups) (ii). Examples of suitable
compounds (C) of this kind are described in detail in
the European patent~application EP 0 928 800 A1, page 3
Lines 17 to 54 and page 4 lines 41 to 54, or in the
German patent application DE 198 18 735 Al, column 3
line l6,to column 6 line 33. Tt is preferred to use
isocyanato acrylates, which are preparable from
CA 02449209 2003-11-26
- 3S -
polyisocyanates and the above-described hydroxyl-
containing monomers (al) and/or (a2).
The coating materials of the invenfiion preferably
comprise at least one photoinitiator.~ preferabl y at
least two and in particular three photoinitiators (D),
in an amount of from 0.2 to 5~, preferably from 0.3 to
4.80, more preferably from 0.4 to 4.6~a, with particular
preference from 0.5 to 4.5~, and in particular from 0.5
to 4.3~ by weight, based in each case Qn the solids of
the coating material of the invention.
Examples of suitable photoir~itiators .(D) are described
in Rompp I,exikon Lacke and Druckfarben, Georg Thieme
Verlag, Stuttgart, New York, 1998, pages 444 to 446.
Photoinitiators (D) are commercially customary
compounds and are sold, for example, by BASF
Aktiengesellschaft under the brand name LUCIRTN~, by
Ciba Specialty Chemicals under the brand name
IRGACURE~, and by Rahn under the brand name GENOCURE~.
Furthermore, the' coating materials of 'the invention may
comprise at least .one additive (E) selected from .the
group consisting of thermally curable reactive
~diluents; molecularly dispersely soluble dyes; light
stabilizers, such as~ W absorbers and reversible free-
radical scavengers (HALS); antioxidants; low-boiling
and high-boiling ("long") organic solvents;
CA 02449209 2003-11-26
- 36 -
devolatilizers; ~ wetting agents; emulsifiers; slip
additives; ~ polymexization inhibitors; thermal
crosslinking catalysts; thermolabile free-radical
initiators; adhesion promoters; leveling agents; film
formation auxiliaries; rheological aids, such as
thickeners and pseudoplastic sag control agents, SCAB;
flame retardants; corrosion inhibitors; free-flow aids;
waxes; siccatives; biocides, and flatting agents.
Examples of suitable additives (E) are described in
-detail in the textbook "Lackadditive" [Additives for
coatings] by Jahan Bieleman, Wiley-VGH, Weinheim,
New Yor3c, 1998, in D. Stoye and W. Freitag (editors),
"Paints, Coatings and Solvents", .second , completely
revised edition, Wiley-VCH, Weinheim, New Xork, 1998,
"14.9. solvent groups", pages 327 to 373, in the German
patent application DE 199 14 896 A1, column 14 line 26
to 'column 15 line 46, or in the German patent
application DE 199 08 018 Al, page 9 line 31 to page 8
i
2C1 line 30. For further details, refer to the German
patent applications DE 199 04 317 A1 arid
DE 198 55 125 A1.
The coating materials of the invention that comprise
the above-described constituents (A) and (B) arid also,
where appropriate, (C), (D) and/or (E) are used, in
particular, as clearcoat materials of the invention fcr
producing clearcoats.
CA 02449209 2003-11-26
., ~ ' ..
The pigmented coating materials of the invention
further comprise at Least one pigment (F) selected from
the group consisting of organic and inorganic,
transparent and hiding, color and/or ~ effect,
electrically conductive, magnetically shielding., and
fluorescent pigments, fillers, and nanoparticles..
The pigmented coating materials of the invention are
employed in particular as primer-surfacers, basecoat
r
materials and solid-color topcoat materials of the
invention for producing ' primer-surfacer coats or
antistonechip primer coats, basecoats, and solid-color
topcoats of the invention,
Z5 Where exclusively nonhiding, transparent pigments (F),
especially nanoparticles (F), are used, the pigmented
coating materials of the invention may also be used as
clearcoat materials.
In terms of its method, the preparation of the coating
materials of the invention has no special features but
instead takes place by the mixing and homogenizing of
the .above-described constituents using customary and
known mixing techniques and equipment such as stirred
vessels, stirred mills, extruders, kneaders,
Ultraturrax, in-line dissolvers, static mixers,
toothed-ring dispersers, pressure release nozzles
and/or microfluidizers, preferably in the absence of
actinic radiation.
CA 02449209 2003-11-26
_ gg _
The resulting coating materials of the invention. may be
conventional coating materials, containing organic
solvents, aqueous coating materials, substantially or
fully solvent-free and water-free liquid coating
materials (100 systems), substantially or fully
solvent-free and water-free solid coating materials
(powder coating materials}, or substantially or fully
solvent-free powder coating suspensions (powder
i
slurries). Moreover, they may be one -component systems,
in which the binders (A) and the crosslinking agents
(C) are present alongside one another, or two-component
or multicomponent' systems, in which the binders (A) and
the crosslinking agents (C). are present separately from
one another until shortly before application.
Tn terms of its method; the application of the dual-
cure coating materials for use in the process of the
invention has no special features but may instead take
place by any customary and known application method
suitable for' the coating material in question, such as
electrodeposition coating, spraying, knife coating,
brushing, flow coating, dipping, trickling ar rolling,
for example. Preference is given to employing spray
application methods, such as compressed air spraying,
airless spraying, high-speed rotation, electrostatic
spray application (ESTA), alone or in conjunction with
hot spray application such as hot air sprayzng, for
CA 02449209 2003-11-26
.L ._ 39
example,.except where the coating materials in question
are powder coating materials:
i
The application of the powder coating materials also
has no special features in terms of its method but
instead takes place, far example, by the customary and
known fluidized bed techniques, such as are known, for
example, from the BASF Coatings AG company brochures
"Pulverlacke fur industrielle Anwendungen" [powder
coating materials for industrial applications],
January 2,000, or "Coatings Partner, Pulverlack Spezial"
[Coatings Partner, powder coatings special],1/2000, or
RQmpp Zexikon ~ Lacke und_ Druckfarben, Georg Thieme
Verlag, Stuttgart, New York, 1998, pages 187 and 188,
I5 "electrostatic powder spraying", "electrostatic
spraying", and "electrostatic fluidi.zed bath process".
In the course of application it is advisable to operate
F, in the absence of actinic radiation in order to prevent
premature crosslinking of the coating materials of the
invention.
The curing of the dual-cure coating materials employed
in the process of the invention generally takes place
after a certain rest period or flash-off time. This may
have a duration of 5 s to 2 h, preferably from l min to
2 h, and in~ particular from 1 min to 45 min. The rest
period is used, for example, for leveling and
devolatilization of the coating films and for the
CA 02449209 2003-11-26
evaporation of volatile constituents such as any
solvent and/or water present. Flashing off may be
accelerated by an'inc.reased temperature, but .one less
than that sufficient for curing, and/or by a reduced
atmospheric humidity.
In the context of wet-on-wet techniques, this process
measure also may be employed for the drying of applied
coating films, particularly electrocoat, primer-
surfacer and/or basecoat films, which are not to be
cured or are to be only part-cured.
The thermal cure takes place, for example, with the aid
of a gaseous, lit~uid and/or solid. hat medium, such as
hot air, heated oil or heated rollers, or of microwave
radiation, infrared light and/or near infrared (NTR)
light. Heating preferably takes place in a forced air
oven or by exposure to IR and/or NIR lamps. As in the
case of the actinic radiation cure, the thermal cure
may also take place in stages. Advantageously, the
- thermal cure takes place at temperatures from worn
temperature up to 200°C.
In the actinic radiation (especially UV radiation) cure
it is preferred to employ a dose o,f from 500 to 4 000,
more preferably from 1 000 to 2 900, with particular
preference from 1 200 to 2 800, with very particular
preference from 1 300 to 2 700, and in particular from
1 400 to 2 600 mJ/cm2.
CA 02449209 2003-11-26
- 41 -
The actinic radiation. cure is .carried out using the
customary and 'known radiation sources and .optical
auxiliary measures. Bxamples of suitable radiation
sources are flash lamps from the company VISIT, high
pressure or low-pressure mercury vapor lamps, with or
without lead doping, in order to open up a radiation
window of up to 405 nm, or electron beam sources. Their
arrangement is known in principle and may be adapted to
t:
the circumstances of the workpiece and the process
parameters. In the case of workpieces of complex shape,
such as those envisaged for automobile bodies, those
areas which are not accessible to direct radiation
(shadow areas), such as cavities, folds and other
structural undercuts, may be cured using pointwise,
small-area or all-round emitters, in conjunction with
an automatic movement means for the. irradiation of
cavities or edges.
y
The equipment and conditions for these curing methods
are described, for example, in R. Holmes, U.V. and,E.B.
Curing Formulations for Printing Inks, Coatings and
Paints, STTA Technology, Academic Press, London,
United Kingdom 1984, or in the German patent
application DE 198 18 735 A1, column 10 line 31 to
column 11 line 1.6.
Curing here may take place in stages, i.e., by multiple
exposure to light or actinic radiation. It may also be
CA 02449209 2003-11-26
- g2 -
carried out alternatingly, i.e., by curing alternately
with W radiation and electron beams, for example.
The thermal cure and actinic radiation cure may be
employed simultaneously or in succession. Where the two
methods of curing 'are employed in succession, it is
possible, for example, to commence with the thermal
cure and to end with the actinic radiation cure. In
ather cases it may prove advantageous to begin and to
end with the actinic radiation cure.
Preferably, curing with actinic radiation is carried
out under inert gas to prevent ozone formation. Instead
of a straight inert gas, an .oxygen-depleted atmosphere
may be used.
"Oxygen-depleted" means that the oxygen content of the
atmosphere is less than the oxygen content of -air
(20.95% by volume). The maximum content in the oxygen-
depleted atmosphere is preferably 18~, more preferably
16~, with particular preference 14~, with very
particular preference 1Q°s, and in particular 6.0o by
volume. The minimum oxygen content is preferably O.lfl,
more preferably 0.5~, with particular preference 1.0%,
with very particular preference 1.50, and in particular
2.0~ by volume.
The oxygen-depleted atmosphere may be provided in a
variety of ways. For example, an appropriate gas
CA 02449209 2003-11-26
- 43 -
mixture may be prepared and made available in pressure
bottles. The depletion is preferably achieved by
introducing .at least one inert gas in the requisite
amounts into the air cushion located above 'the surface
of the dual-cure films (2) that are to be cured. The
oxygen content of the .atmosphere located above the
surface in question may be measured continuously with
the aid of customary .and known methods and equipment
for determining elemental oxygen . and may, where
1Q appropriate, be adjusted automatically to the desired
level. .
By inert gas is meant a gas which under the curing
conditions employed is not decomposed by the actinic
radiation, does not inhibit,.curing, and/or does' not
react with the dual-cure coating material of the
invention: Preference is given to using nitrogen,
carbon dioxide, helium, ,neon or argon, especially
nitrogen and/or carbon dioxide.
The above-described curing and application processes
and apparatus may also be used for noninventive coating
materials, such as electrocoat materials, primer-
surfacers or basecoat materials, which are. used
together with the coating materials of the invention. to
produce multicoat clearcoat systems and multicoat color
and/or effect paint systems.
CA 02449209 2003-11-26
- 94 -
Examples of suitable electrocoat materials and, where
appropriate, of wet-on-wet techniques are described in
the Japanese patent application 1975-142501 tJapanese
laid-open specification JP~52-065534 A2, Chemical
Abstracts report 'No. 87: 137427) or in the patents and
patent applications US 4,375,498 A1, US 4,537,926 A1,
US 4,761,212 Al, EP 0 529 335 A1, DE 41 25 459 A1,
EP 0 595 186 A1, EP 0 074 634 A1, EP 0 505 445 A1,
,DE 42 35 778 A1, EP 0 646 420 A1, EP 0 639 660 A1,
1
EP 0 817 698.A1, DE 195 12 017 Cl, EP 0 192 113 A2,
DE 41 26 476 A1 and WO 98/07794.
Suitable primer-surfacers, especially aqueous primer-
surfacers, Which are also referred to as antistonechip
primer coats or functional coats, are known from the
patents and patent applications US 4,537,926. A1,
EP 0 52.9 335 A1, EP 0 595 186 A1, EP 0 639 660 A1,
DE 44 38 504 A1, DE 43 37 961 A1, WO 89/10387,
US 4,450,200 A1, US 4,614,683 A1 and WO 94/26827.
Suitable basecoat materials, especially aqueous basecoat
materials, are known from the patent applications
EP 0 089 497 A1, EP 0 256 540 A1, EP 0 260 447 A1,
EP 0 297 576 A1, WO 96/12747, EP.O 523 610. A1,
EP 0 228 003 A1, EP 0 397 806 Al, EP 0 574 917 A1,
EP 0 531 510 A1, EP 0 581 211 A1, EP 0 708 7$8 A1,
EP 0.593 454 A1, DE-A-43 28 092 A1, EP 0 299 148 A1,
EP 0 399 737 A1, EP 0 590 484 A1, EP 0 234 362 A1,
EP.O 234 361 Al, EP 0 593 817 A1, WO~95114721,
CA 02449209 2003-11-26
_ _ _
45
EP 0 521 928AI, EP 0 420 Al., EP 0 522 419 Al,
522
EP O 649 865A1',~ EP 0 712 A1, EP 0 596 460 A1,
536
EP 0 596 461A1, EP- 0 818 A1, EP 0 669 356 A1,
584
EP 0 634 431A1, EP 0 536 A1, EP 0 354 261 A1,
678
EP 0 424 705A1, WO /49795, WO /49747,
97 97
EP 0 401 565A1 and 0 684, column lines 31 ,to
EP 8I7 5
45,
The coatings, of the invention obtained, especially the
single-coat or multicoat color and/or effect paint
systems and clearcoats of the invention, are easy to
produce and have outstanding optical properties and
very high overbake stability, light stability,. chemical
resistance, water resistance, condensation resistance,
weathering stability, yellowing resistance, and etch
resistance. In particular, they are free from
turbidities and inhomogeneities. They have very good
reflow properties and combine outstanding scratch
s. resistance with high hardness.
The film thicknesses of the inventive and noninventive
coatings are preferably situated within the ranges that
are commonly employed:
Electrocoat:
Preferably from 10 to 60, more preferably from 15 to
50, and in particular from 15 to 40, um;
CA 02449209 2003-11-26
. .
Primer-surfacer coat:
Preferably~from 20 to~150, more preferably from 25 to
100, and.in particular from 30 to 80, Vim;
Basecoat:
Preferably from 5 to 30, more preferably from 7.5 to
25, and in particular from 10 to 20, um;
Solid-color topcoat:
'z
Preferably from 10 to 60, more preferably from 15 to
50, and in particular Pram 15 to 40, um;
Clearcoat:
Preferably from 10 to 200, more preferably from 15 to.
80, and in particular from 20 t.o 70, um.
A further advantage of the coating materials of the
invention is that, even in the shadow zones of three-
dimensional substrates of complex shape, such as.
vehicle bodies, radiators or electrical wound products,
and even without optimum, in particular, complete
exposure of the shadow zones to actinic radiation, they
give coatings whose profile of performance properties
at least approaches that of the coatings outside of the
shadow zones. As a result, the coatings present within
the shadow zones are alsa no longer easily damaged by
mechanical and/or chemical attack, as may occur, for
example, on the line during the installation of further
motor vehicle components into the coated bodies.
CA 02449209 2003-11-26
. _ 47
In particular, however, the coatings of 'the invention
are notable for outstanding wettability, which makes it
possible to . apply extensive refinishes and, repeat
finishes without problems, and without the need to
carry out the above-described physical, mechanical
and/or chemical treatments beforehand. Clearcoat
materials of the invention may be applied to inventive
clearcoats or noninventive- or inventive basecoats and
inventive cleareoats may be applied to the inventive
clearcoat. In t.h.e same way, solid-color topcoats of the
invention may be coated ,with inventive solid-color
topcoats. Where necessary, it is also possible to
incorporate the primer-surfacers into the refinish or
repeat finish. Further possible combinations are
obvious to the skilled worker and need not be recited
explicitly.
The inventive ar noninventive coating materials used
for the refinish or repeat finish need. not necessar~.ly
be materially identical, or substantially identical,
with those of the original finish. What is important is
that they and the coatings produced from them have the
same profile of performance properties, in order that,
for example, there arise no deviations in shade between
refinish or repeat finish on the one hand and original
finish on the other.
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_ qg
The dual-mode curing results in refinishes and repeat
finishes which adhere extremely firmly to the original
finishes, do not delaminate even following condensation
exposure, and have the same advantageous .properties as
the original.finishes.
The coating materials of the invention may also,
however, be used as adhesives and sealing compounds for
producing adhesive films and seals of the invention and
t
may serve for the coating, bonding.and/or. sealing of
primed or unprimed substrates made of metal, plastic,
glass, wood, textile, leather, natural stone and
artificial stone, concrete, cement, or composites of
these materials.
The coating materials, adhesives or sealing compounds
of the invention may therefore be used to coat, bond
and seal motor vehicle bodies and parts thereof, the
interior and exterior of motor vehicles, buildings
inside and out, doors, windows, furniture, and for
coating, bonding and sealing in the context of the
industrial finishing of small parts, coils, containers,
packaging, electrical components, and white goods, all
with great success.
The substrates may have been primed.
In the case of plastics, customary and known primer
coats or tie coats may be employed, or the surfaces of
CA 02449209 2003-11-26
99 --
the plastic may have been given a firm-adhesion finish
by flaming or etching with reactive compounds such as
fluorine.
In the case of electrically conductive substrates,
especially metals, the primers used may be those as
described in Rompp Lexikon hacke and Druckfarben, Georg
Thieme Verlag, Stuttgart, New- York, 1998, "primers",
page 973, "wash primers", page 618, or "shop primers",
page 230, '
In the ease of electrically conductive substrates based
on aluminum, the primer ,coat used is preferably an
aluminum oxide layer produced by anodic oxidation.
1S
Owing to the outstanding performance properties of the
coatings, adhesive films and seals of the invention,
the substrates that are coated, bonded and/or sealed
with them nave a particularly long service life and so
are particularly valuable for users from an economic,
environmental, and technical standpoint.
Inventive and comparative examples
Preparation example 1
The preparation of a thermally curable bindex
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~x, .. 5 O -
In an appropriate reactor equipped with a stirrer, two
dropping funnels for the monomer mixture and the
initiator solution, a nitrogen inlet pipe, thermometer,
heating system, and reflex condenser, 650 parts by
weight of an aromatic hydrocarbon fraction with a
boiling range from 158 to 172°C were weighed in. The
solvent was heated to 140°C. Thereafter a. monomer
mixture of 652 parts .by weight of ethylhexyl acrylate,
383 parts by weight of 2-hydroxyethyl methacrylate,
143 parts by weight of styrene, 212 parts by weight of
4-hydroxybutyl acrylate arid 21 parts by weight of
acrylic acid .was metered into the initial charge at a
uniform rate over the course of four hours and an
initiator solution of 113 parts by weight of the
aromatic solvent and 113 parts by weight of tert-butyl
perethylhexanoate was .metered into the initial charge
at a uniform rate over the course of 4.5 hours. The
addition of the monomer mixture and of the initiator
solution was commenced simultaneously. After the end of j
the initiator feed, the resulting reaction mixture was
heated at 140°C for two hours more, with stirring, and
was then cooled. The resulting solution of the
methacrylate copolyme r (A) was diluted with a mixture
of 1-methoxypropyl 2-acetate, butyl glycol acetate and
butyl acetate. The resulting solution had a solids
content of 65°s by weight, determined in a forced air
oven (one hour/130°C) and an acid number of 15 mg KOH/g
solids.
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4, - 51 -
Inventive example l and comparative examples C1 and C2
The preparation of an inventive clearcoat material
(example I) and of noninventive dual-cure clearcoat
materials (examples Cl and C2)
The dual-cure clearcoat materials 1, C1 and C2 were
prepared by mixing the constituents indicated in the
table, in the stated order, and homogenizing the
( 10 resulting mixture.
Table: The material compositions of the dual-cure
clearcoat materials 1, C1 and C2
constituent Parts by weight
1 C1 C2
Stock varnish:
Binder from preparation example 1 35.9 35.9 35.9
Dipentaerythritol pentaacrylate 20 20 20
UV absorber (substituted hydroxy-
phenyltriazine) 1.0 7..0 1.0
HALS (N-methyl-2,2,6,6-tetramethyl-
piperi~dinyl ester) 1.0 1.-0 1.0
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Constituent Parts by ght
wei
1 C2 C2
Silicane additive (Byk~ 306 from Byk
Chemie) - 0.4 -
Additive (B) (8ykt~3 35$ from Byk
Chemie) p.2 _ _
Butyl acetate 27.6 27:4 27.8
Solventnaphtha~ 10.8 10.8 10.8
Irgacure~ 184 (commercial photo- 2.0 2.0 2.0
'
initiator from Ciba Specialty.
Chemicals)
Genocure~ MBF (commercial photo- 1.0 1.0 1.0
initiator from Rahn)
Zucirin~ TPO (commercial photo-. 0.5 0.5 0.5
initiator from BASF AG)
Total.: I00 100 x.00
Crosslinki.nq component (B)
Crosslinkinc~ agent (B 1);
Isocyanato acrylate Roskydal~ UA VPLS
2337 from Bayer AG (basis: trimeric
hexamethylene diisocyanate; isocyanate
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- 53 -
group content: 12~ by weight) 27.84 27.84 27..84
Crosslinking agent (B 2):
Isocyanato acrylate based on the
trimer of isophorone diisocyanate
(70.5 in butyl acetate; viscosity:
1 500 mPas; isocyanate group content:
6.7's by weight: prepared analogously
to example 1 of EP 0 928 800 A1) 6.96 6.96 6.96
Diluent ~ 3.48 3.48 3.48
Total: 38.28 38.28 38.28
Inventive example 2 and comparative examples C3 and C~4
The production of an inventive multicoat paint system
i, 5 (example 2) and of noninventive multiaoat paint systems
(examples C3 and C4)
For example 2, the clearcoat material from example 1
was used.
For example C3, the clearcoat material from example C1
was used.
For example C4, the clearcoat material from example C2
was used.
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To produce the multicoat paint systems 2, C3 and C4,
steel panels were coated in succession with an
electrocoat, deposited cathodically and baked at 170°C
for 20 minutes, with a dry film thickness of from l8 to
22 um. The steel panels were then coated with a
commercially customary two-component waterborne primer-
surfacer from BASF Coatings AG, as is commonly used for
plastics substrates. The resulting primer-surfacer film
was baked at 90°C for 30 minutes so as to give a dry
film thickness of from 35 to 40 um. Thereafter a
commercially customary black aqueous basecoat material
from BASF Coatings AG was applied with a film thickness
of from 12 to 15 ~zm, after which the resulting aqueous
basecoat films were flashed off at 80°C for ten .
minutes. The clearcoat materials were .then applied
pneumatically using a gravity-feed cup gun in one cross
pass, with a film thickness of from 40 to. ~!5 ~zm. The
aqueous basecoat films and the clearcoat~ films were
cured at room temperature for 5 minutes, at 80°C for
10 minutes, .followed by exposure to UV light in a dose
of 1 500 mJ/cm2, and finally 'at 140°C~ for 20 minutes.
The multicoat paint systems 2, C3 and C9 had a very
good profile of properties in terms of gloss, hardness,
and scratch resistance.
They were very bright and had a gloss (20°) to
DIN 67530 of 90. The micropenetration hardness
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55 -
(universal hardness at 25.6 mN, Fischerscope 100V with
Vickers diamond pyramid) was 137 to 139.
The scratch resistance was assessed using the sand test
tcf. the German patent application DE 198 39 453 A1,
page 9 lines 1 to 63) on the basi s of the metal test
panels described above. The loss of gloss was 10 units
(20°) . _
The scratch resistance was also assessed using the
brush test (cf. the German patent application
DE 198 39 453 A1, page 9 lines 17 to 63) on .the basis
of the metal test panels described above. The loss of
gloss was 4 units (20°).
In the MB gradient oven test, which is known to those
skilled in the art, initial damage to the inventive
multicoat paint systems by sulfuric acid was evident
only above a temperature of 53°C, and that caused by
tree resin only above 55° Celsius. The etch resistance
was also outstanding.
The multicoat paint systems 2 and C3 showed very good
leveling and.a surface which was free from defects,
without popping marks. The multicoat paint system C4
had pinholes in its surface, and other flow defects.
The intercoat adhesion was very good (cross-cut test in
accordance with DIN EN ISO 2409: GTO-1).
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- 56 -
Significant differences arose, however, with the
adhesion between the inventive multicoat paint system 2
and its refinishes, on the one hand, and the
noninventive multicoat paint systems C3 and C9 and
their refinishes, on the other and also in the case of
the systems
- basecoat (original)/clearcoat (original)/basecoat
(refinish) /clearcoat (refinish) (= 'repeat finish)
and
- basecoat (original)/clearcoat (original)/clear-
I5 coat (refinish) (= clearcoat refinish),
when the clearcoats of the original finishes had not
been sanded prior to application of the refinishes.
r
r
Table 2 gives an overview of the results of the cross-
cut test to DIN EN ISO 2909 following five-day aging of
the metal test. panels. The adhesion in accordance with
the cross-cut test was scored as follows:
GTO-1 - satisfactory, very little or no delamination
(small splinters at the edges of the cut);
GT2 - still just satisfactory, slight delamination,
about 15$ of the pieces;
~' CA 02449209 2003-11-26
y- 57
GT3-9 - unsatisfactory, extensive areas of
delamination, from about 35 to 650 of the pieces;
GTS - complete delamination..
~ Table 2: Cross-cut test an metal test panels of
inventive example 2 and camparative.exa;nples
C3 and C4
System Example
2 C3 C4
Repeat finish GT1-2 GT5 GTO-1
Clearcoat refinish GT2 n.m.a} GT2
a) not measurable, overcoating not possible because
the refinish clearcoat did not wet the original
Clearcoat
