Note: Descriptions are shown in the official language in which they were submitted.
r -
2 1L ~
Coating compo~ition and th~ use thereof i~ the production
~f coating3 with a rapidly workable ~urface
The invention relates to coating composition formulations,
which give rise to coatings with a rapidly workable
surface. They are particularly suitable as formulations for
clear and topcoat lac.quers.
Coating compositions based on CH-acid compounds and
olefinically unsaturated compounds are known. For example,
two component lacquers containing such components are
described in EP~A-O 224 158. These two component lacquers
are heat curable; the curing reaction is catalysed by Lewis
and/or Br~nsted bases. In EP-A-O 227 454, acetoacetate
polymers are described as crosslinking agents for
acryloyl-unsaturated acrylates. Such systems are suitable
for the production of various coatings.
In the production of coatings, particularly multilayer
coatings in the automotive sector, it is often necessary to
~orm layers, the surface of which is rapidly curable in
order to achieve the shortest possible dwell time ~or
vehicle bodies in the painting booth.
Rapid curing is achieved in a known manner by W
irradiation of coating compositions containing unsaturated
components. A disadvantage of this approach is insufficient
crosslinking with opaquely pigmented systems in thicker
layers or in concealed areas which are not reached by the
W light. These disadvantages may be overcome by the use of
so-called double cure systems.
It is known in the literature to use a so-called double
cure system to produce such layers, which system may be
initially cured by W radiation and subsequently thoroughly
cured conventionally by heating. Such a system is described
in EP-A-O 247 563; this is a two component system
comprising a radiation-curable oligomer with at least two
(meth)acrylate groups, an OH-functional polymer, a
: . . : : . ~ .: . :
.. . .
.: , .: ~ : : ~. . :
. : . . . .
polyisocyanate, light stabilisers and photoinitiators.
Polyisocyanates are not without toxicological problems.
EP-A-0 245 639 describes the production of stable, scratch
resistant and solvent resistant coatings which contain
opaque pigments. In addition to an unsaturated polyester,
the system contains cellulose nitrate, pigments,
hydroperoxides, driers and photoinitiators; in this
process, the use of peroxides has attendant risks. Even
thicker layers of the systems are intended to be radiation
curable.
The object of the invention is to provide coating
compositions which produce coatings with a rapidly worXable
surface which may be formulated without toxicologically
questionable polyisocyanates and require no peroxides.
Mechanically and chemically stable sur-faces are intended to
be achieved.
It has been found that this object may be achieved with a
coating composition which contains:
A) 10 - 80 wt.~ of one or more compounds with on average
at least two CH-acid hydrogen atoms as crosslinking
agent,
2S
B) 10 - 80 wt.% of one or more ~,B-unsaturated compounds
with at least two identical or different groups of the
general formula
RlR2C=CR3--~--
which are linked together by the residue of a di~ or
polyhydric alcohol, a di- or polyamine or
aminoalcohol, in which R1, R2 and R3 are mutually
independently a hydrogen atom or a straight or
branched alkyl residue with 1 to 10 carbon atoms,
which residue may be olefinically mono- or
. - , . .. .. . : '~ ' '
''
polyunsaturated and/or may have one or more hydroxyl
groups,
C~ 0 - 50 wt.% of one or more radically or ionically
polymerisable compounds,
D~ 0.01 - 5 wto%, related to the sum of the weights of
components A), B), and C), of a catalyst in the form
of a Lewis or Br~nsted base, wherein the conjugate
acids of the latter have a pKA value of at least 10,
E) 0.1 to 10 wt.%, related to the sum of the weights of
components A), B), and C), of one or more
photoinitiators, optionally together with
~5
pigments and/or extenders, optionally together with
auxiliary substances and additives customary in lacquers
and optionally one or more organic solvents and/or water.
According to the invention, the CH-acid crosslinking agents
used as component A) in the coating compcsitions according
to the invention are those containing at least two CH-acid
hydrogen atoms. These may, for example, originate from one
or more of the following groupings, which may be the same
or different:
W3~W2
I
W1
0 0 0
in which W1 = -~- -C-{}~ P=0, -CN or -~2;
0 0 0
11 11 11 ~ \ .
W2 - --C~ P=0, or--CN;
,
~0 0 0 0
Il 11 11 1 ~,~
W3 ~ {~ H~ alkyl or alkene;
: . . - . - :. .
,
.. ~ ..... . . .
- : ~ . .:
2 ~
wherein the carboxyl or c~arbonamide groups defined above
for the residues W1, W~ and W3 are each bonded to the CH
group via the carbon atom and the CH group is bonded via at
least one of the residues W1, Wz and/or W3 to a polymeric or
oligomeric unit. The CH-acid functionality of component A)
is on av~rage > 2 per molecule. ~herefore, if W3 in the
above general formula means a hydrogen atom, then such a
group is suf~icient since the group has two acid hydrogen
atoms.
As mentioned above, the CH-acid functionality of component
A) is on average > 2. This means that monofunctional
molecules may also be used mixed with higher-functional
molecules.
Those CH-acid crosslinking agent compounds are preferred
which are substantially free of primary, secondary or
tertiary amino groups, as these can have a negative
inf]uence on storage stability and light stability.
Listed below are examples of CH-acid crosslinking compounds
A which fall within the above general formula. These
examples are subdivided below into three groups Al, A2 and
~3.
In group Al, on average at least two groups with active H
atoms of the type
-C-~
are contained in each molecule, which groups are derived
from methanetricarboxylic acid monoamide units or
acetoacetic acid ester-2-carboxylic acid amides.
Suitable compounds Al are, for example, reaction products
of malonic acid diesters such as dimethyl, diethyl,
.
"'.
2 ~
dibutyl, dipentyl malonate or acetoacetic acid esters such
as methyl, ethyl, butyl or pentyl acetoacetate with
polyisocyanates.
Examples of polyisocyanates usable for this purpose are
aliphatic, cycloaliphatic or aromatic polyisocyanates with
at least two isocyanate groups, such as tetramethylene
diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethyl-
hexamethylene diisocyanate, 1,12-dodecane diisocyanate,
cyclohexane-1,3 and -1,4 diisocyanate, 1-isocyanato-
3,3,5-trimethyl-5-isocyanato-methylcyclohexane
(= isophorone diisocyanate, IPDI), perhydro-2,4'- and/or
-4,4'-diphenylmethane diisocyanate, 1,3- and 1,4-phenylene
diisocyanate, 2,4 and 2,6-tolylene diisocyanate,
diphenylmethane-2,4' and/or -4,4' diisocyanate, 3,2'-
and/or 3,4-diisocyanato-4-methyl-diphenylmethane,
naphthylene-1,5 diisocyanate, triphenylmethane-4,4'-4''
triisocyanate, tetramethylxylylene diisocyanate or mixtures
of these compounds.
Apart from these simple isocyanates, those isocyanates
containing heteroatoms in the residue linking the
isocyanate groups are also suitable~ Examples of these are
polyisocyanates having carbodiimide groups, allophanate
groups, isocyanurate groups, urethane groups, acylated urea
groups and biuret groups.
Particularly well suited to the reaction are the known
polyisocyanates which are main]y used in lacquer
production, for example modification products of the
above-stated simple polyisocyanates containing biuret,
isocyanurate or urethane groups, in particular tris-(6-
isocyanatohexyl)-biuret or low molecular weight
polyisocyantes with urethane groups, as may be obtained by
the reaction of an excess of IPDI with simple polyhydric
alcohols o~ the molecular weight range 62 - 300,
particularly with trimethylolpropane. Naturally, any
:
: . . . . :
. . : - : : ~
6 2 ~
desired mixtures of the stated polyisocyanates may also be
used for the production of crosslinking component A1.
Further suitable polyisocyanates are the known prepolymers
having terminal isocyanate groups, as are in particular
accessible by the reaction of the above--stated simple
polyisocyanates, principally diisocyanates, with
substoichiometric quantities of organic compounds with at
least two groups capable of reacting with isocyanate
grcups. The compounds used to this end are preferably any
such compounds having at least two amino groups and/or
hydroxyl groups with a number average molar mass of 300 to
10,000, preferably 400 to 6,000. It is preferably the
corresponding polyhydroxyl compounds which are used, for
example the hydroxypolyesters, hydroxypolyethers and/or
acrylate resins containing hydroxyl groups which are known
per se in polyurethane chemistry.
In these known prepolymers, the ratio of isocyanate groups
to hydrogen atoms reactive with NCO is 1.05 to 10:1,
pre~erably 1.1 to 3:1, wherein the hydrogen atoms
preferably originate from hydroxyl groups.
The type and quanti~y ratios of the starting materials used
in the production of the NCO prepolymers are furthermore
preferably sPlected such that the NCO prepolymers have a)
an average NCO functionality of 2 to 4, preferably from 2
to 3 and b) a number average molar mass of 500 - 10,000,
preferably from 800 - 4,000 glmol.
Suitable compounds Al are also, however~ the reaction
products of esters and partial estexs of polyhydric
alcohols of malonic acid with monoisocyanates. Polyhydric
alcohols are, for example, di- to pentahydric alcohols such
as ethanediol, the various propane~, butane~, pentane- and
hexanediols, polyethylene and polypropylene diols,
glycerol, trimethylolethane and -propane, pentaerythritol,
, . : '' . . '
,~
. ' ' ' '
.:
~ 7
hexanetriol and sorbitol. Suitable monoisocyanates are, for
example, aliphatic isocyanates such as n-butyl isocyanate,
octadecyl isocyanate, cycloaliphatic isocyanates such as
cyclohexyl isocyanate, araliphatic isocyanates such as
benzyl isocyanate or aromakic isocyanat:es such as phenyl
isocyanate.
Also suitable are the corresponding malonic esters and
acetoacetic acid esters of acrylic resins, polyesters,
polyurethanes, polyethers, polyester amides and imides
containing OH groups, and/or reaction products of malonic
acid semi-esters such as malonic acid monoethyl ester with
aliphatic and aromatic epoxy resins, for example acrylate
resins containing epoxy groups, glycidyl ethers of polyols
such as hexanediol, neopentyl glycol, diphenylolpropane and
-methane and hydantoins containing glycidyl groups,
together with mixtures of these compounds.
The examples of the following group A2 exhibit a suitable
curing component with active CH groups, which component
contains as least two groups of the formula ~I)
X
\
C~
or structural units of the formulae (I') or (I'')
X'-C~-K'- tI~) -X'-C~
I
Y y~
in which:
O O
Il 11 ~,
K means -C- or -~-{}-
- :
. .
.,: . . -- : . , . . - .
: . . : : ,
'. .: ' : .
. .
- , . . . . .
.
8 2 ~
wherein the latter group is bonded to the CH group via the
C atom;
X and Y are the same or different and are
R1-C-
-C02R1, ~CN, -~Oz, -CQNH2, -CONR1H or -CONRlR1~ wherein the
residues R1 may be the same or different and stand for a
hydrocarbon residue, preferably an alkyl residue with 1 to
12, preferably 1 to 6 C atoms, which residue may also be
interrupted by oxygen or an N-alkyl residue, with the
proviso that only one of the two residues X, Y can
represent the NO2 group;
O O
Il 11
K' means -C- or -C-~}-
wherein the latter group is bonded to the CH group via the
C atom;
X' and Y' are the same or different and mean
2~ 1l 1
-C-{~- or -C~
with the proviso that, if K' and X' simultaneously mean
O
--C~ :.
the residue Y' preferably does not mean
11
.
, ' ,~
.~ . .. .
.. , . : ,
,
- .
.
The number of (I) groups in the curing agent according to
the invention is preferably 2 to 203 and in particular 2 to
lO, wherein the higher numbers refer to oligomeric or
polymeric products, in which case they are averages as
mixtures may be present.
The curing component A2 usable according to the invention
preferably has the formula ~II)
X
C~-K- __R2 (II)
Y n
in which X, Y and K have the above meaning, R2 represents
the residue of a polyol
11
R2(OH)n (wherein K = -C-{}-)
or the residue R2 of a polycarboxylic acid
2 5 1l
R2 (COOH) n (wherein ~C = -C-)
and n means at least 2, preferably 2 to 2001 in particular
2 to lO. In the case of oligomeric or polymeric curing
components these figures are again average values.
Also preferred are curing components coming within group A2
which are obtained by transesterification of compounds of
the formula (III) or the formula (IV)
RlOOC R100C ~
C~_~ (III) C~ 1 (IV)
.4G
X R10OC
.
- - . - , - . .
. : . : . .
~, . . ..
. : . , :
with polyols R2(OH) n~ wherein X, K and R1 have the above
meaning .
The above-stated polyols R2(OH) n may be a polyhydric
alcohol, preferably containing 2 to 12, in particular 2 to
6 C atoms. Examples of such polyols are: ethylene glycol,
(1,2)- and (1,3)-propylene ylycol, (1,4)- and
(2,3)-butylene glycol, di-B-hydroxyethylbutanediol,
(1,6)-hexanediol, (1,8)-octanediol, neopentyl glycol,
~1,6)-cyclohexanediol, 1,4-bis-(hydroxymethyl)-cyclohexane,
2,2-bis-(4-hydroxycyclohexyl)-propane, 2,2-bis-(4-(~-
hydroxyethoxy)phenyl)-propane, 2-methyl-1,3-propanediol,
glycerol, trimethylolpropane, (1,2,6)-hexanetriol-
(1,2,4)-butanetriol, tris-(B-hydroxyethyl)-isocyanurate,
trimethylolethane, pentaerythritol and their
hydroxyalkylation products, together with diethylene
glycol, triethylene glycol, tetraethylene glycol,
polyethylene glycols, dipropylene glycol, tripropylene
glycol, polypropylene glycols, dibutylene glycol,
polybutylene glycols and xylylene glycol. Those polyesters
may also be used which are obtained from or with lactones,
for example ~-caprolactone or hydroxycarboxylic acids, such
as for example hydroxypivalic acid, ~-hydroxydecanoic acid,
~-hydroxycaproic acid, thioglycolic acid. In such
polyhydric alcohols the index n in the above formula (II~
preferably stands for 2 to 4.
Alternatively, the polyol may be an oligomeric or polymeric
polyol compound (polyol resin), the number average
molecular weight of which, Mn (determined by gel
chromatography; polystyrene standard), is customarily in
the range from approximately 170 to approximately 10,000,
pre~erakly approximately 500 to approximatPly 5,000. In
special cases) the number average moleculax weight may,
however, be 10,000 and over. Polymers, polycondensates or
polyaddition compounds may here be considered as
oligomers/polymers. The hydroxyl value is generally 30 to
' ~ , :
250, preferably 4S to 200 and in particular 50 to
180 mg KOH/g. These compounds containing OH groups may
optionally contain further functional groups, such as
carboxyl groups.
Examples of such polyols are polyether polyols, polyacetal
polyols, polyesteramide polyols, polyamide polyols, epoxy
resin polyols or their reaction products with C2~ phenolic
resin polyols, polyurea polyols, polyurethane polyols/
cellulose ester and ether polyols, partially saponified
vinyl ester homo- and copolymers, partially acetalised
polyvinyl alcohols, polycarbonate polyols, polyester
polyols or acrylate resin polyols. Polyether polyols,
polyester polyols, acrylate resins and polyurethane polyols
are preferred. Such polyols, which may also be used mixed
together, are, for example, described in DE-OS 31 24 784.
Examples of polyurethane polyols are produced from the
reaction of di- and polyisocyanates with an excess o~ diols
~0 and/or polyols. Suitable isocyanates are, for example,
hexamethylene diisocyanate, isophorone diisocyanate,
tolylene diisocyanate together with isocyanurates, formed
from three moles of a diisocyanate such as hexamethylene
diisocyanate or isophorone diisocyanate and biurets
produced from the reaction o~ three moles of a diisocyanate
with one mole of water. Suitable polyurea polyols may be
obtained in a similar manner by the reaction o~ di- and
polyisocyanates with equimolar quantities of amino
alcohols, ~or example ethanolamine or diethanolamine.
Examples of polyester polyols are the known polycondensates
prepared ~rom di- or polycarboxylic acids or their
anhydrides, such as phthalic anhydride, adipic acid etc.,
and polyols such as ethylene glycol, trimethylolpropane,
~lycerol etc..
, , .! ' . . . .
.~, '
'' : , ,
12
Suitable polyamide polyols may be obtained in a similar
manner as the polyesters, by at least partially replacing
the polyols with polyamines, such as isophorone diamine,
hexamethylene diamine, diethylene triamine etc..
Examples of polyacrylate polyols or polyvinyl compounds
containing OH groups are the known copolymers prepared from
(meth~acrylic acid esters containing hydroxyl groups or
vinyl alcohol and other vinyl compounds, such as for
example styrene or (meth)acrylic acid esters.
The above polycarboxylic acids R2(CO2H) n/ wherein n is here
preferably 2 to 4, may be of an aliphatic, cycloaliphatic,
aromatic and/or heterocyclic nature and optionally
substituted and/or saturated, for example with halogen
atoms. The following are stated as examples of such
carboxylic acids and their derivatives: succinic acid,
adipic acid, suberic acid, azelaic acid, sebacic acid,
phthalic acid, terephthalic acid, isophthalic acid,
trimellitic acid, pyromellitlc acid, tetrahydrophthalic
acid, hexahydrophthalic acid, di- and tetrachlorophthalic
acid, endomethylenetetrahydrophthalic acid and its
hexachloro derivative, 1,4 and 1,3-cyclohexanedicarboxylic
acid, glutaric acid, maleic acid, fumaric acid, dimeric and
trimeric fatty acids, such as oleic acid, optionally mixed
with monomeric fatty acids ox cyclic monocarboxylic acids,
such as benzoic aci.d, p~tert-butylbenzoic acid or
hexahydrobenzoic acid. Together with the reaction products
o~ the above-stated polyols R2(OH) n with cyclic carboxylic
acid anhydrides.
The curing component A2 which may be used according to the
invention comprises, depending on the type of polyol or
polycarbbxylic acid component, higher or lower viscosity
liquids or solids, which are largely soluble in at least
customary lacquer solvents and preferably contain less than
5 wt.%, in particular less than 1 wt.%, of crosslinked
,
2 ~
components. The CH equivalent weight, which is an
indication of the quantity of groups (I) or structural
units (I')/(II''~ in (A2), is generally between 100 and
5,000, preferably 200 and 2,000 and the number average
molecular weight M~ is as a rule between 200 and 10,000,
pr~ferably between 500 and 5,000 (determined by gel
chromatography, polystyrene standard). Processes for the
production of such compounds are described in more detail
in EP A-0 310 011.
Further examples of curing agent components usable
according to the invention are those of type A3, in which
the CH grouping is derived from a compound with the
grouping -Co-CHR3-Co-, NC-CHR3-Co-~ NC-CHz-CN, =Po-CHR3-Co-
~
=Po-CHR3-CN, =PO--CHR~ PO=, -Co-CHR3-No2~ in which R3 is C1-C8
alkyl, H, preferably hydrogen. B-dioxo compounds are
preferred.
The above A3 groupings may be bonded to at least one
polyvalent monomeric or polymeric compound. They may, for
example, be bonded to at least one compound f rom the group
of mono- or polyhydric alcohols, polymers, polyamines and
polymercaptans containing OH groups. The compounds are
polyvalent in relation to the CH functional group. They may
thus, for example, be produced by esterificat.ion oE a
polyepoxide with a -CH carboxylic acid which ~orms the
yrouping, for example cyanoacetic acid. In this manner, a
component A3 is obtained with two active H atoms per epoxy
group. Aromatic or aliphatic polyepoxides may be used in
this instance.
Suitable examples of compounds of the type A3 are ketones,
such as acetylacetone, benzoylacetone, acetyl-
dibenzoylmethane, together with esters of, optionally
alkyl~substituted, acetoacetic acid such as ~- and/or
~-methylacetoacetic acid, or of acetone dicarboxylic acid,
malonic acid units with an ester-type linkage of malonic
, , , -: . . : ~
: , , : . .
. . , :,. , ': ''
. . . . .: .: . . : : ~ : .
.: . :
. -
,: . . .:
2 ~
14
acid and its monoalkyl derivatives, straight chain or
branched, with 1 to 3 C atoms in the alkyl residue, for
example methyl, ethyl and n~butyl or also phenyl, or of
cyanoacetic acid with mono- to hexahydric alcohols with 1
to 10 C atoms. The alkyl-substituted esters, for example
~-methyl or ~,~-dimethylacetoacPtic estert have only one
active H atom and are therefore preferably used in the form
of di- or polyesters of polyhydric alcohols in order to
have a sufficient number of reactive groups available.
Suitable alcohols for the esterification of the above acids
are, for example, methanol, ethanol, butanol, octanol
and/or, and this is preferred, polyhydric alcohols or
polyhydroxy compounds. Further examples of A3 are, for
example, acetoacetic ester, ethanediol bisacetoacetic
ester, glycerol tris~malonic acid ester, trimethylolpropane
tris-acetoacetic ester, partial esters of these acids with
polyhydric alcohols, together with corresponding esters of
acrylic resins, polyesters, po].yethers, polyester amides
and imides containing OH groups, polyhydroxylamines,
together with nitriles of these acids, to the extent that
they exist, for example malonic acid mono- or dinitrile,
alkoxycarbonyl-methanephosphonic acid ester and the
corresponding bis-methanephosphonic acid ester. The
above-stated acids may also be bonded in the form of amides
to amines, preferably polyamines, which also include
oligomers and/or polymers including amine resins, wherein
aliphatic amines are preferred.
If polyamines are the starting material, compounds A3 may
be produced in the form of amides. Thus, for example, it is
possible to skart from 1 mole of an alkene diamine which i5
reacted with 2 moles of acetoacetic ester ko a form a
compound which also has four H atoms activated by amide
groups.
Reactive nitro compounds are suitable compounds for A3, for
example nitroacetic acid derivatives, such as tris-
.. . . ~
. .
2~
(nitroacetic acid)-glycerol ester or trimethylolpropane~
nitroacetic acid ester.
Among the compounds for A3 which form groups of the type
~CH-, diketene and its mono-~-alkyl substitution products,
together with tetrahydrodioxin, should be mentioned, which
may react with suitable components to form acetoacetic
ester or amide groups.
The curing agent components A may be produced in customary
solvents. It is favourable to use solvents which will not
later disrupt production of the coating composition. It is
also favourable to Xeep the content of organic solvents as
low as possible. I~ the curing agent component A contains
polar groups, for example amide or urethane groupings, it
may be readily dispersed in watex. This may optionally also
be promoted by the cros~linking component~' containing
neutralisable ionic groups, for example carboxyl ~roups, in
the oligomer or polymer skeleton. Such crosslinking agents
with ionic groups may be readily dispersed in wa~er. In
this manner, the content of organic solvents may be reduced
to low levels without substantially increasing the
viscosity of the crosslinking agent solution.
The binder compositions according to the invention may also
contain 2-acetoacetoxy-ethylmethacrylate as a reactive
diluent to adjust viscosity.
~ compound is used in the binder compositions according to
the invention as a further ~inder component B), which
compound has at least two unsaturated groups of the general
formula tV) RlRzC--CR5-CO-~ in which R1, R2 and R3 are defined
as in the claims. These groups may be bonded together via
short or long chain residues, oligomers and/or polymers of
di- or polyhydric alcohols, di- or polyamines or
aminoalcohol, wherein these oligomers and polymers may, for
example, have a number average molecular weight Mn ~ 100 to
,.
.:' :', ,- . ,
' . : . : . .
.- - ~ . .
.. . .. ~ :
.. ... . .
, . , ,: .` . , : ~
,
2~9~
16
10,000. Oligomers and polymers which may, for example, be
considered are saturated and/or unsaturated polyethers,
polyesters or polyurethanes containing two or more hydroxyl
groups, for example those based on maleic acid, phthalic
acid and diols, acrylic resins contain:ing hydroxyl groups,
aliphatic or preferably aromatic epoxy r~sins, optionally
containing hydroxyl groups, for example those ba~ed on
diphenylolpropane and~or diphenylolmethane, hydantoin
and/or amine resins. The residue of the general formula (V)
may here be bonded with an ester-type linkage, for example
by the reaction of glycidyl (meth)acrylate with carboxyl
groups from acid-functional polyethers, polyesters,
polyurethanes or poly(meth)acrylates or by addition of
acrylic or methacrylic acid or their derivatives onto epoxy
resin epoxy groups or by esterification of polyol hydroxyl
groups. Suitable polyhydric alcohols are, for example,
alkanediols and triols with 2 to 8 carbon atoms such as
ethanediol, the various propane, butane, hexane and octane
diols, or their homologues, the corresponding oligomeric
ethers, together with glycerol, trimethylolethane or
trimethylolpropane, hexanetriol, pentaerythritol,
dipentaerythritol, sorbitol and polyvinyl alcohol together
with ethoxylated and propoxylated variants.
The groups of the general formula (V) may also be bonded
via NH groups andtor OH groups to polyamines with at least
two NH groups or at least one NH group and at least one OH
group. Starting compounds containinc3 NH groups for such
compounds which may be stated are, for example, di- and
polyamines, such as alkene diamines and their oligomers,
such as e~hylenediamine, propylenediamine,
diethylenetriamine, tetramines and higher homologues of
these amines, toc3ether with aminoalcohols such as
diethanolamine or the like. Amines which may be considered
are also, for example, aminocarboxylic acid esters of
polyhydric alcohols. Compounds wi-th NH groups which may be
considered are, for example, acrylic or methacrylic acid
.
. :: : , . :
... : ~....... . . .
. .
,, . : .
: :
.~
17
polyamides, together with polyurethanes, for example
polyisocyanates, which are capped in the form of
polyurethane groups, such as thosP obtained by the reaction
of hydroxyethylacrylate with polyisocyanates, amine resins
such as methoxymelamines, preferably hexamethylol melamine,
urea resins, wherein the residue of the general formula (V)
is bonded with the -CO grouping to the amine groups of
these compounds as an amide. I~ these amine compounds have
OH groups or hydroxyalkyl groups, it is also possible that
the residue of the formula (V) is bonded with an ester-type
linkage or instead via an ether group to these compounds.
The starting material for ether bonding of the residue of
the formula (V) may be a hydroxyalkyl ester or a
hydroxyalkyl amide of an unsaturated acid such as acrylic
acid.
The residue of the general formula (V) in component B) may
be derived from a mono or polyunsaturated monocarboxylic
acid, ~or example with 2 to 10, preferably 3 to 6 carbon
atoms, such as cinnamic acid, crotonic acid, citraconic
acid, mesaconic acid, dihydrolaevulinic acid, sorbic acid,
preferably acrylic acid and/or methacrylic acid.
It is also possible to use adducts prepared from copolymers
of the compound ~-dimethyl-m-isopropenylbenzylisocyanate
(called m-TMI in the remainder of the text) with
hydroxy(meth)acrylic monomers. The comonomers which may be
used for copolymerisation with m-TMI are, for example,
customary ~meth)acrylic acid esters, as have already been
mentioned in the explanations concerning the polyols.
Possible hydroxylmeth)acrylic monomers for adduct formation
with m-TMI copolymers are, for example, hydroxyethyl
~meth)acrylate, hydroxypropyl (meth)acrylate or butanediol
monoacrylate. It is also possible to use addition products
3S of hydroxyethyl methacrylate onto caprolactone.
.
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Examples of component B are hexanediol dilmeth)acrylate and
dipropylene glycol di(meth)acrylate and examples of tri-
and tetrafunctional monomers are trimethylolpropane
tri(meth)acrylate and pentaerythritol tri- or
tetra(meth)acrylate, together with ethoxylated and
propoxylated variants. The term (meth)acrylate used here
means acrylates and/or methacrylates. Examples of oligomers
or prepol~ners are (meth)acrylic-funct:ional (meth)acrylic
polymers, epoxy resin (meth)acrylates, for example reaction
products prepared from 2 moles of (me-th)acrylic acid and
commercial epoxy resins, such as for example Epicote~ 828,
polyester (meth)acrylates, amine (meth)acrylates,
unsaturated polyesters, unsaturated polyurethanes, silicone
(meth)acrylates or combinations thereof.
Component B) may contain no solvents or it may, however,
contain residual solvent from its production, for example
aliphatic and/or aromatic hydrocarbons. Solids content may
be adjusted to desired values, for example by removing
residual solvent, for example by distillation, or hy the
addition of water or solvents which are required ~or the
subse~uent preparation of coating compositions and are
described below. The same solvent is preferably used as for
component A).
The coating compositions according to the invention may
also contain as component C) in the binder component
additional materials curable by high-energy radiation,
which may be monomers, oligomers or polymers or copolymers.
They are subject to no restrictions. They may be both
radically and ionically polymerisable compounds. Radically
polymerisable compounds are preferred, wherein these may
also favourably be present as a mixture with ionically
polymerisable compounds.
Examples of radically polymerisable compounds are customary
radiation curable compounds, which are in particular used
,
:
lg
in UV-curable lacquers, based on monomers, oligomers,
polymers, copolymers or combinations thereof with one or
more olefinic double bonds, such as, Eor example, acrylic
acid and methacrylic acid esters. Examples of
monofunctional monomers are butyl (meth)acrylate and
hydroxyethyl (meth)acrylate. Examples of difunctional
monomers are diacrylates, as were listed above as examples
for component B)~
lo Vinyl compounds may, however, also be present as monomers.
Thesa may be mono- and/or polyfunctional monomers. Examples
of monofunctional monomers are hydroxybutyl vinyl ether,
styrene, N-vinylpyrrolidone. Examples of polyfunctional
monomers are butanediol divinyl ether, cyclohexane divinyl
ether.
Component D) consists of catalysts in the form of Lewis
bases or Br~nsted bases, wherein the conjugate aclds of the
latter have a pKA value of at least 10. Component D) may
consist of one or more catalysts. Lewis bases prove to be
particularly suitable, such as for example those from the
group of cycloaliphatic amines, such as diazabicyclooctane
(DABCO), tert.-aliphatic amines, such as triethylamine,
tripropylamine, N-methyldiethanolamine,
N-methyldiisopropylamine or N-butyldiethanolamine, together
with amidines such as diazabicycloundecene (DBU) and
guanidines, such as for example N',N',N',N'-tetramethyl-
guanidine. Further examples are alkyl or aryl substituted
phosphanes, such as Por example tributylphosphane,
triphenylphosphane, tris-p-tolylphosphane, mathyl-
diphenylphosphane/ together with hydroxy and amino
functionalised phosphanes, such as for example tris-
hydroxymethylphosphane and tris-
dimethylaminoethylphosphane.
Examples of usable Br~nsted bases are alkoxides, such as
sodium or potassium ethylate, quaternary ammonium
. . : . : ' ' '..
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2 ~
compounds, such as alkyl-, aryl- or benzylammonium
hydroxides or halides, such as for example tetraethyl- or
tetrabutyl ammonium hydroxide or fluoride, together with
trialkyl or triaryl phosphonium salts or hydroxides.
The quantity of catalysts is generally 0.01 to 5 wt.%,
preferably 0.02 to 2 wt.%, related to the total solids
content of components A, B and C.
The coating compositions according to the invention contain
as component E customary photoinitiators, as are used for
radical and ionic polymerisation. By way of example,
initiators absorbing within the wavelength range of 190 to
400 nm are suitable.
Examples of usahle radical initiators are initiators
containing chlorine, such as aromatic compounds containing
chlorine, for example described in US-A-4,089,815; aromatic
ketones, as described in US-A-4,318,791 or EP-A-0 003 002
and EP-A-0 161 163; hydroxyalkylphenones, as described in
US~A-4,347,111; water-soluble initiators, for example based
on hydroxyalkylphenones, as described in US-A-4,602,097,
unsaturated initiators such as OH-functional aromatic
compounds, which have, for example, been esterified with
acrylic acid, as described in US-A-3,929,490,
EP-A-0 143 201 and EP-A-0 341 560; or combinations of such
initiators, as are, for example, described in
US-A-4,017,652.
Specific examples are 2-methyl-2-hydroxy~propiophenone,
benzophenone, thioxanthone derivatives, acylphosphine
oxides and Michler's ketone.
Particularly preferred usable radical initiators are
phosphine oxides and combinations of phosphine oxides with
other customary initiators, as described above.
- ~ . : '
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21
Examples of usàble cationic initiators are
triarylsulphonium salts of the general formula
(aryl)3 S' X- ,.
in which aryl represents an aryl residue, such as the
phenyl residue, and X- is an anion such as SbF6-, PF~, AsF6~
and BF4, as described in US-A-4,417,061, EP-A-0 327 194 and
DE-A-2 904 626. Further examples of cationic initiators are
iodonium salts, oxonium salts and diazonium salts, as are,
for example, described in the following references:
EP-A-0 464 131, US-A-4,421,904, EP-A-0 145 633,
EP-A-0 310 881, EP-A-0 310 882 (iodonium salts~;
DE-A-3 808 590 and DE-A-3-808 591 (diazonium salts).
Apart from these initiators, metallocene complexes may also
be used, as are, for example, described in EP-A-0 094 915.
The binder compositions according to the invention are
so-called two component systems.
Components A, B, C, and E are stored together as binder
component 1 and component D is stored as curing agent
component 2.
This means that components 1 and 2 are stored separately
and are only mixed together just ~efore use or for use, for
example, in the production of coating compositions.
The coating composition formulations according to the
invention may contain up to 80 wt.% Qf pigments and/or
extenders related to total solids, including resin and
curing ag~nt.
Extenders which may be used are, for example, sulphates
such as barium sulphate, silicas, such as pyrogenic silicas
(aerGsils) and silicates, such as talc.
.
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22
Pigments which may be used are those customary in lacquers.
These are customary opaque inorganic or organic pigments
such as titanium dioxide, ultramarine blue, iron oxides and
phthalocyanine blue, together with effect pigments such as,
for example, metallic flake pi~ments or pearlescent
pigments.
Further auxiliary substances and additives which may
optionally be used are thixotroping agents, smoothing
agents, flatting agents and flow-control agents.
The coating composition formulations according to the
invention may contain organic solvents and/or water.
Suitable organic solvents for the production of coating
composi-tions, for example lacquers, are those as may also
be used in the production of the individual components A
and B. Examples of such solvents are organic solvents such
as aliphatic and aromatic hydrocarbons, for example
toluene, xylene, mixtures of aliphatic and/or aromatic
hydrocarbons, esters, ethers and alcohols. These are
customary lacquer solvents. Aqueous solutions may also be
prepared for the production of coating compositions from
the binders according to the invention. To this end,
suitable emulsifiers may optionally be used as are
customary in the lacquers sector.
The coating compositions produced from the binders
according to the invention may be adjusted to the desired
application viscosity by appropriate control of the
addition of solvents and/or additivesO
Further auxiliary substances and additives which may be
added are sensitisers. These are preferably organic
aromatic compounds with/without hekeroatoms. Examples of
aromatic sensitisers without heteroatoms are anthracene and
perylene. Examples of aroma~ic sensitisers with heteroatoms
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23
are thioxanthene derivatives, xanthone derivatives and
sulphonium complex salts.
Depending on the quantity ratio of component 1 to component
2, equivalent weight and catalyst quantity, the coating
compositions may be adjusted to a pot life of between a few
minutes and 24 hours.
Application of the coating compositions so produced may
proceed in a customary manner, for example by dipping,
spraying, brushing or electrostatically. Subsequently, any
optionally present solvents or water are vaporised by heat
treatment (for example infra-red irradiation or hot air).
The two component coating compositions according to the
invention are radiation curable after application and
optionally evaporation of solvents. In particular, they are
suitable for curing by irradiation with W radiation or
electron beams. Combinations of IR/ W irradiation or
IR/electron beam irradiation are also suitable. Radlation
sources which may be used are those customary for W or
electron beam irradiation, such as high and medium pressure
mercury lamps. In thicker layers, thorough curing
subsequently proceeds, for example within a few hours, by
Michael addition.
As mentioned, after application to a substrate to be
coated, the coating compositions according to the invention
may rapidly be superficially cured by irradiation. By way
of example, curing of the surface layer up to a depth of
2 mm is possible within 10 minutes. This makes lt possible
to work the surface immediately, for example by sanding.
The coating compositions according to the invention have
the advantage that they may be formulated without solvents
or with only small quantities of solvent. The coating
compositions according to the invention may furthermore be
.
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24
formulated such that they contain no toxic constituents,
such as for example styrene.
It is naturally also possible to formulate the coating
compositions according to the invention as a single
component formulation without component D and to follow the
radiation curing stage with thermal post:-treatment at
elevated temperatures of, for example, 100 - 150C.
A particularly preferred sector for the use of the binders
according to the invention is in the preparation of coating
compositions for lacquer coatings in the automotive sector.
Due to the favourable curing conditions of coating
compositions produced from the binders according to the
invention, these coating compositions are also particularly
suitable for automotive repair lacquers.
The invention is illustrated with the following examples.
All parts and percentages (%) relate to weight.
Production example 1
Production of an acetoacetic ester functionalised polyester
(component A)
la) Production of the polyester
336.7 parts of trimethylolpropane, 366.9 parts of
adipic acid and 297 parts of hexanediol are combined
with 5 parts o~ hypophosphorous acid in a 2 litre
three-necked ~lask with stirrer, separator,
thermometer and reflux condenser. The mixture is
slowly heated from 180C in a melt to 230C, water
being separated. The reaction is continued until an
acid value of 20 mg KOH/g is reached. The mixture is
then condensed under a water-jet vacuum down to an
acid value of ~ 1.5 mg KOH/g. The resultant polyester
then has an OH value of 466 mg KOH/g and a viscosity
of 3200 mPa.s.
~ . :
:
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lb) Production of an acetoacetic-functionalised polyester
on the basis of the polyester produced under la.
1000 parts of the polyester produced under la) are
introduced into a 4 litre three-necked flask fitted
with stirrer, dropping funnel, separator and reflux
condenser. To this resin are added 850 parts of
acetoacetic ester and 1.5 parts of 98% formic acid and
the mixture is heated to 130C, ethanol being
separated. The resin is ~urther heated to 165C until
a total of 400 parts of distillate have been
separated. All volatile constituents are then stripped
out under a vacuum. The 98.1% resin obtained then has
a viscosity of 3100 mPa.s and a colour value of 65
Hazen.
1~
lc) Production of trimethylolpropane triacetoacetate
670 parts of trimethylolpropane and 1g50 parts of
acetoacetic acid ethyl ester are introduced into a 4
litre three-necked flask fitted with a stirrer, reflux
condenser, thermometer and dropping funnel. The
mixture is heated while being stirred until ethanol is
eliminated. After 4 hours, 488 g of distillate have
been produced; the temperature is 175C. A vacuum is
applied and distillation continued until a total of
806 g of distillate have been obtained. The
acetoacetic ester functional component lc then has a
theoretical solids content of 96.5%, a viscosity of
172 mPa.s and an acid value of 131.6 mg KOH/g of solid
resin.
Exam~l~ 2
Grafted polyester resin 2b (component B):
2a) Unsaturated polyester resin
140.0 parts of trimethylolpropane, ~35.0 parts of
neopentyl glycol, 370.0 parts of 1,6-hexanediol `~
together with 409.0 parts of tetrahydrophthalic
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26
anhydride, 294.0 parts of maleic anhydride, 352.0
parts of phthalic anhydride and 0.8 parts of
hydroquinone are weighed out into a reaction vessel
fitted with a stirrer, thermometer and distillation
column with a water separator on top. After addition
of 160 parts of xylene, the mixture is heated under a
nitrogen atmosphere. At a maximum temperature of
195C, water is removed from the system until the acid
value is less than 30 mg KOH/g of solid resin. The
mixture is then cooled and the distillation column
replaced with a distillation bridge. The added xylene
is distilled off under a vacuum at 120C. Final
values: solids (lh/150C): 99.3%, acid value: 29.9 mg
KOH/g solid resin, viscosity: highly viscous, colour
value (Gardner): 2-3
2b) Grafting of la) with glycidyl methacrylate
In a reaction vessel with a stirrer, thermometer and
reflux condenser, 2000.0 parts of polyester resin 2a)
are combined with 126.6 parts of glycidyl methacrylate
and 4.2 parts of triphenylphosphine and heated to
120C under a nitrogen atmosphere. The reaction is
continued at 120C until an acid value of below 5 mg
KOH/g of solid resin is achieved. The mixture is then
diluted with 533 parts of pentaerythritol triacrylate.
Final values: solids (1 h/150C): 98.7%; acid value at
approx. 80% in pentaerythritol triacrylate: 3.5 mg
KOH/g of solid resin.
Grafted polyester resin 2d:
2c) Unsaturated polyester resin
378.0 parts of trimethylolpropane, 1760.5 parts of
neopentyl ylycol, 330.0 parts of 1,6-hexanediol,
1104.5 parts of tetrahydrophthalic anhydride, 1~24.0
parts of maleic anhydride, 2.0 parts of hydroquinone
and 400 parts of xylene are cond nsed in a manner
. . , , : ~ , .
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: :. . : , : .
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2 ~
analogous to la~ until an acid value of below
30 mg KOH/g of solid resin is reached.
2d) Gra~ting with glycidyl methacrylate
The polyester resin produced under 2c) is direc-tly
combined with 291~0 parts of ylycidyl methacrylate and
9.0 parts of triphenyl phosphine. The temperature is
maintained at 120C until an acid value of below
5 mg KOH/g of solid resin is reachedO
3) Clear lac~uer:
Polyester from example lb) 29.0
Polyester from example 2d) 16.0
Photoinitiator: 2-hydroxy-2-methyl-2-phenyl-
propan-1-one 5.u
Pentaerythritol triacrylate 21.0
Commercial polyester acrylate (component B) 28.0
Diazabicycloundecene 1.0
10 0 . O
4) Cleax laaquer:
Polyester from example lc) 40.0
Polyester from example 2b) 22.0
Photoinitiator: 2-hydroxy-2-me-thyl-2-phenyl-
propan 1-one 7.0
Pentaerythritol triacrylate 30.0
Diazabicycloundecene 1.0
100. o
5) Topaoat lacquer:
Polyester Erom example lc) 23.0 '
Polyester from example 2b) 19.0
Photoinitiator: l-hydroxy-cyclohexyl-phenyl
ketone 3.0
Pyrogenic silicon dioxide 0.3
Titanium dioxide 23.0
Commercial polyester acrylate ~component B) 22.0
. .
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28
Pentaerythritol triacrylate 8.0
Diazabicycloundecene 1.7
~oo. o
6) ~urfacin~ compound
Polyester from example lb) 16.5
Photoinitiator: 1-hydroxy-cyclohexyl-phenyl
ketone 3.0
Dipropylene glycol diacrylate 17.0
Pyrogenic silicon dioxide 0.5
Talc 40.1
Extender (Blancfix ~) 10.0
Titanium dioxide 2.0
Pentaerythritol triacrylate 9.0
15 ` Diazabicycloundecene 1.9
100. o
The clear or topcoat lacquers from examples 3, 4 and 5 were
applied with a coating kni~e to a wet film thickness o~
approximately 50 ~m and cured by 10 minutes' irradiation
with a Honle type 250 hand lamp (distance 20 cm). The films
have elevated hardness, good gloss and good petrol
resistance and are tack-free after irradiation.
A 1 cm deep indentation ~approximately 1.5 cm3) was filled
with the formulation described in example 6 using a
spatula. The sur~ace (approximately 2 mm) was cured by 10
minutes' irradiation with a Honle type 250 hand lamp
~distance 20 cm) and is then workable. The entire
~0 ~ormula~ion then thoroughly cures overnight.
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