Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~ CA 02239310 1998-06-02
FILE, PIN Ihl THIS An~utl~
F TRANSLAT~ON
PAT 95 628 20.11.1995
J ~ BASF ~acke + Farben Aktiengesellschaft, Munster
Radiation-curable aqueous coating materials with a matt
effect
Field of the invention
The invention relates to radiation-curable
aqueous matt-effect coating materials comprising (a) at
least one water-compatible binder containing at least
two ethylenically unsaturated groups, (b) at least one
matting agent, (c) water, with or without acid as
neutralizing agent, (d) optionally, further fillers
and/or pigments, (e) optionally, photoinitiators, and
(f) optionally, other auxiliaries and/or additives.
Prior art
It is known to cure compositions based on
acrylic esters by means of radiation, especially UV
radiation. However, a problem which occurs here is that
the presence of air is a disruptive factor when
surfaces are being cured.
DE-C 26 25 538 discloses photopolymerizable
coating compositions which include amines as reducing
agents and/or chain transfer compounds. The use of a
free amine of this kind has the disadvantage that it
may act as a plasticizer and lead to an unwanted
covering on the surface and to odor pollution.
By incorporating the amino group into a
molecule which still contains polymerizable groups, an
amine is obtained which is copolymerized in the course
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of curing and does not exhibit the abovementioned
disadvantages. One known method of incorporation is the
addition of amines onto molecules rich in double bonds,
which takes place in analogy to a Michael addition and
iS described, for example, in F. Moller, Houben-Weyl,
Vol. 11/1 (1957), pages 277 to 280. US-A 2,759,913
teaches the addition of amines onto activated, olefini-
cally unsaturated compounds, such as acrylates, in
equimolar amounts, leading to complete reaction of the
activated ethylenic double bonds. Systematic investi-
gations into the addition of amino alcohols onto
acrylates have been carried out by N. Ogata and
T. Asahara, Bull. Chem. Soc. Jap. 39, pages 1486 to
1490, 1966.
DE-C 23 46 424 describes the preparation of
radiation-curable compositions starting from acrylic
esters of polyhydric alcohols and secondary, aliphatic
monofunctional amines. These compositions have the
disadvantage of reduced stability on storage. The
20 addition reaction of a secondary amine leads, moreover,
to a reduction in the acrylic ester functionality of
the molecule and therefore also to a reduction in the
crosslinking possibilities for the radiation-induced
polymerization.
EP-A-0 280 222 discloses addition products of
esters of acrylic or methacrylic acid and polyhydric
alcohols with primary monoamines, the molar ratio of
monoamine to (meth)acrylic double bond of the ester
being from 0.05 : 1 to 0.4 : 1. The addition products
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of EP-A-0 280 222 are employed in radiation-curable
compositions which cure in the air. The storage
stability, however, of the products known from EP-A-
0 280 222 is inadequate. For instance, during storage
of the addition products there is a marked increase in
viscosity. Moreover, compatibility problems occur in
the case of addition products formed from tetrahydric
polyols with the primary monoamines. Products of this
kind are cloudy and/or have a milky white appearance. A
further disadvantage of the amine-modified compositions
described in EP-A-0 280 222 is that a relatively high
proportion of monoamine is required in order to ensure
sufficiently high nitrogen contents in the resulting
addition products for systems, for example, initiated
using benzophenone. Sufficiently high nitrogen contents
are required in order, given the customary radiation
dose, to ensure photopolymerization which is sufficient
in practice and proceeds to completion.
EP-A-0 002 457 describes plastics for shaped
plastics components, where the plastics cure at
elevated temperatures. The plastics involved are
Michael addition products of acrylic ester monomers and
amines having an amine hydrogen functionality of at
least 3. The components are reacted in a ratio of
equivalents of acrylate to amine hydrogen of from 0.5
to 2Ø
US Patents Nos. 4,547,562 and 4,675,374 dis-
close radiation-curable, solvent-free compositions
based on polyacrylates and mono-, di- or polyamines.
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Suitable di- and polyamines specified are species
having more than one primary amino group. When these
polyamines are used, highly crosslinked coating com-
positions of reIatively high molecular mass and there-
fore relatively high viscosity are obtained which,without the addition of reactive diluents and solvents,
have an application viscosity which is too high, or
even lead to solid products.
US-A 4,045,416 and US-A 3,845,056 relate to
radiation-curable coating compositions based on amine
acrylates, which are obtained by reacting polyacrylates
with amines having at least one amine hydrogen. Suit-
able amines specified are primary and secondary mono-
amines and also polyamines. As polyamine components the
US Patents specify polyamines having more than one
primary amino group, polyamines having only secondary
amino groups, or polyamines having secondary and
tertiary amino groups. When polyamines having more than
one primary amino group are used, nonhomogeneous addi-
tion products of low storage stability are obtained,while the use of polyamines with only secondary amino
groups, such as piperazine, for example, leads to non-
homogeneous mixtures as a result of inadequate
reactivities or of instances of incompatibility. The
use of polyamines having secondary and tertiary amino
groups leads only to a reduction in the acrylic and/or
methacrylic ester functionality of the molecule.
The coating compositions described are used in
particular for decorative purposes, a particular
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decorative effect being obtained on wooden substrates,
for example, by the use of matting coating com-
positions.
Matt surfaces are generally achieved by texturing the
surface with the aid of so-called matting agents.
In this context, common commercial coating compositions
based on the prior art either do not achieve the
reduction in the degree of gloss which is necessary to
obtain the matt effect at all, or achieve it only
through the use of solvents which are objectionable on
ecological and/or health grounds. Moreover, in the case
of customary commercial coating compositions there are
frequently problems of distribution between the
particular matting agents employed and binders,
problems which lead to fluctuations in the degree of
gloss and inhomogeneities on the coating surface.
Problem and solution
The object resulting from this, there~ore, was
to overcome the above-described disadvantages and to
provide radiation-curable coating materials which
possess adequate stability on storage, good reactivity,
low viscosity and comparatively good resulting film
properties, such as, in particular, ~ilm hardness.
It was additionally the intention, in particular on
ecological grounds, to manage substantially without the
use of monomer additives, or so-called reactive
diluents, as well as without the addition of organic
solvents.
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The resulting coating was to have good adhesion to the
substrates, especially to critical substrates, for
example film-coated compressed woods or to plastics,
such as polyvinyl chloride or polypropylene.
In particular, the intention was to provide coating
materials which make it possible to obtain coatings
with a matt surface up to a dully matt appearance,
coupled with very substantial avoidance of organic
solvents and/or reactive monomeric diluents as coating-
material constituents. Furthermore, there is a require-
ment for maximum uniformity of distribution of the
matting agent in the coating material, especially after
the preparation of the coating, in order to facilitate
high processing safety.
Surprisingly, it has been found that radiation-
curable aqueous coating materials with a matt effect,
comprising:
(a) from 40 to 85% by weight, preferably from 50 to
75% by weight, of at least one water-compatible
binder containing at least two ethylenically
unsaturated groups,
(b) from 1 to 20% by weight, preferably from 5 to 15%
by weight, of a matting agent,
(c) from 5 to 40% by weight, preferably from 10 to 30%
by weight, of water, with or without an acid as
neutralizing agent,
(d) from 0 to 25% by weight, preferably from 0 to 20%
by weight, of further fillers and/or pigments,
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(e) from 0 to 6% by weight, preferably from 3 to 5% by
weight, of photoinitiators for use in UV, and
(f) from 0 to 15% by weight, preferably from 0 to 10%
by weight, of other auxiliaries and/or additives,
are an outstanding solution to the problems presented
at the outset.
In this context, it is preferred as binders (a)
to employ (meth)acrylic esters of preferably ethoxy-
lated polyols, which are water-compatible; that is, are
miscible with water, at least within defined mixing
ratios, without visible phase separation. Water-
compatibility of this kind is preferably realized with
(meth)acrylicized polyetherpolyols, consisting of an
ethoxylated polyol having a molecular weight of from
600 to 1000 daltons which is esterified with
(meth)acrylic acid, which preferably has an OH number
of ~rom 150 to 350 mg o~ KOH/g and a viscosity of ~rom
300 to 1000 mPas, which is preferably ethoxylated from
to 20 times, which preferably is composed of
ethoxylated pentaerythritol, which preferably consists
of from 50 to 75% by weight of polyetherpolyol, from 20
to 50% by weight of (meth)acrylic acid and from 0 to 5%
by weight of customary auxiliaries, and which prefer-
ably contains UV initiators, particularly preferably
benzophenone.
In a further embodiment of the invention, the
water-compatibility of the (meth)acrylic esters can be
achieved by the addition of di- and/or polyamines (B)
onto the abovementioned (meth)acrylic esters,
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preferably onto the abovementioned (meth)acrylicized
polyetherpolyols, and subsequent neutralization of the
amino groups with an acid.
Preferred di- and/or polyamines (B) are diamines having
a primary and tertiary amino group, the ratio of the
primary amino groups of the diamines (B) to the
(meth)acrylic double bonds of the oligomers and/or
polymers (A) being from 0.01 : 1 to 0.2 : 1., parti-
cularly preferably from 0.03 : 1 to 0.1 : 1.
Further preferred matting agents (b) are
preferably surface-treated phyllosilicates or poly-
amides of low density.
Practice of the invention
The water-compatible binder (a)
The (meth)acrylicized polyetherpolyol employed
in accordance with claim 3 as water-compatible binder
(a) consists of an ethoxylated polyol with a molecular
weight of from 500 to 1000, preferably from 700 to
90Q daltons, which is esterified with acrylic acid
and/or methacrylic acid.
In a preferred embodiment of the invention, the
(meth)acrylicized polyetherpolyol (a) consists from 50
to 75% by weight, pre~erably from 55 to 65% by weight,
of polyetherpolyol, from 20 to 50% by weight,
preferably from 30 to 45% by weight, of (meth)acrylic
acid, and from 0 to 5% by weight of customary
auxiliaries.
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The ether alcohols employed generally have a degree of
ethoxylation of from 10 to 20, preferably from 13 to
17, the degree of ethoxylation indicating the number of
moles of ethylene oxide which are added on in average
to 1 mole of a polyol used as starter molecule.
Particular preference is given to using ethoxylated
tri- and/or tetrahydric alcohols having a degree of
ethoxylation of from 3 to 6 and a molecular weight of
from 224 to 400 daltons. Ethoxylated pentaerythritol
with a molecular weight of from 500 to 1000, preferably
from 700 to 900, daltons is preferably employed. An
example is pentaerythritol etherified with 15 ethoxy
units.
The compounds involved are preferably polyetherpolyols
having an OH number of between 150 and 350, parti-
cularly preferably between 250 to [sic] 320 mg of
KOH/g, and a viscosity of between 300 and 1000, parti-
cularly preferably between 400 and 600 mPas.
The hydroxyl-containing polyethers which are esterified
with acrylic acid and/or methacrylic acid are obtained
by the reaction of the di- and/or polyhydric alcohols
with various amounts of ethylene oxide by well-known
methods (compare for example Houben-Weyl, Volume 14/2,
Makromolekulare Stoffe II, 1963).
The polyetherpolyols are substantially free of pro-
pylene oxide units. This means that, in the course of
the alkoxylation reaction, at best minor amounts of
propylene oxide are allowed to be present in addition
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to ethylene oxide (the molar ratio of ethylene oxide to
propylene oxide is at least 5 : 1).
To prepare the (meth)acrylicized polyetherpolyol, the
technique employed is preferably the following:
first of all, the polyetherpolyol and the (meth)acrylic
acid are heated at from 70 to 110 degrees C, preferably
from 80 to 100 degrees C, in the presence of an
entrainer whose purpose to remove the water of reaction
which is liberated. In this context, suitable
entrainers are only those substances whose boiling
point lie [sic] between 60 and 110 degrees C,
preferably between 70 and 90 degrees C. The reaction
temperature is maintained until the acid number falls
below from 60 to 80 mg of KOH/g, preferably below from
65 to 75 mg of KOH/g. The proportions of the polyether-
polyol here are usually between 50 and 75% by weight,
preferably between 55 and 65% by weight. The
(meth)acrylic acid is added in amounts from 20 to 50%
by weight, pre~erably from 30 to 45% by weight. In
addition, polymerization inhibitors, for example hydro-
quinones, catalysts to accelerate the esterification
reaction, and antioxidants are also added to the
reaction mixture.
In a further embodiment of the invention, the
water-compatible binders (a) consist of addition
products (AB) of oligomers and/or polymers (A) having
at least two acrylic ester and/or methacrylic ester
groups per molecule with di- and/or polyamines (B), the
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amino groups of the addition products (AB) preferably
being neutralized with an acid.
Examples of suitable compounds (A) are the esters of
acrylic acid and/or of methacrylic acid with dihydric
- 5 aliphatic alcohols, such as ethylene glycol, propylene
1,2- and 1,3-glycol, 1,4-butanediol, 1,2-pentanediol,
neopentylglycol, 1,6-hexanediol, 2-methyl-1,5-pentane-
diol, 2-ethyl-1,4-butanediol, dimethylolcyclohexane and
diethylene glycol, preferably with trihydric alcohols,
such as glycerol, trimethylolethane, trimethylolpropane
and trimethylolbutane, preferably with tetrahydric
alcohols, such as pentaerythritol, and also preferably
with alcohols of higher functionality, such as
di(trimethylolpropane), di(pentaerythritol) and sor-
bitol. Also suitable are polyhydric cycloaliphaticalcohols, for example 1,4-bis(hydroxymethyl)cyclo-
hexane, polyhydric araliphatic alcohols, such as 1,3-
xylylenediol, and also polyhydric phenols, such as 2,2-
bis(4-hydroxyphenyl)propane (bisphenol A).
As component (A) it is preferred to use esters of
acrylic acid and/or methacrylic acid and tri- and/or
tetrahydric alcohols.
With particular preference the above-indicated poly-
hydric alcohols are converted, prior to esterification
with acrylic acid or methacrylic acid, into relatively
higher molecular mass ether alcohols by alkoxylation
with, ~or example, ethylene oxide or propylene oxide,
as described previously in connection with the
preparation of the (meth)acrylicized polyetherpolyols.
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This results in the above-described polyether acrylates
or polyether methacrylates. Polyether (meth)acrylates
of this kind are particularly preferably used as com-
ponent (A) in the novel binders (a).
The hydroxyl-containing polyethers which are esterified
with acrylic acid and/or methacrylic acid are obtained
by reacting dihydric and/or polyhydric alcohols with
various amounts of ethylene oxide and/or propylene
oxide in accordance with well-known methods (cf. e.g.
Houben-Weyl, Volume XIV, 2, Makromolekulare Stoffe II,
(1963)). It is also possible to employ polymerization
products of tetrahydrofuran or of butylene oxide.
Also suitable as component (A) are polyester acrylates
and/or polyester methacrylates. To prepare the
polyester (meth)acrylates, hydroxyl-containing
polyesters (polyesterpolyols) are employed as
polyhydric alcohols. These can be prepared by
esterifying dicarboxylic acids with diols and triols in
accordance with well-known methods (cf. e.g.
P.J. Flory, J. Am. Chem. Soc. 58, 1877 (1936) and
J. Am. Chem. Soc. 63, 3083 (1953).
The preparation of polyether acrylates and polyester
acrylates is described, for example, in DE-A-38 36 370.
Examples of diamines which are preferred as
component (B), having a primary and a tertiary amino
group, are N,N-dialkyldiaminoalkanes, such as, for
example, N,N-dimethyl-1,3-diaminopropane, which is
obtainable by catalytic hydrogenation of dimethylamino-
propionitrile. The preparation of this diamine is
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described, for example, in Houben-Weyl, Vol. 11/1,
1957, p. 565, in EP-A-316 761, or in P. Lappe,
H. Springer and J. Weber, Chem.-Ztg. 111(4), pages 117
to 125 (1987).
Further suitable dialkylaminopropanes are N,N-diethyl-
1,3-diaminopropane, N,N-di-n-propyl-1,3-diamin~propane,
4-morpholinopropylamine, 3-(N-piperidinyl)propylamine,
N,N-diphenyl-1,3-diaminopropane.
Also suitable as component (B) of the novel addition
products are: N,N-dialkyl-1,2-diaminoethane deriva-
tives, such as, for example, dimethylaminoethylamine,
diethylaminoethylamine, N-beta-aminoethylmorphline (for
preparation see for example Houben Weyl, Vol. 11/1,
1957, p. 563), N,N-dialkyl-1,5-diaminopentane deriva-
tives, which can be prepared by 1,4 addition ofsecondary amines onto 1-cyano-1,3-butadiene, with
formation of the nitrlles, and subsequent catalytic
hydrogenation (for preparation see Houben-Weyl,
Vol. 11/1, 1957, p. 276). Examples of suitable N,N-
dialkyl-1,5-diaminopentane derivatives are dimethyl-
aminopentylamine, diethylaminopentylamine, 4-morphol-
inepentylamine.
A particularly preferred amine component (B) is N,N-
dimethyl-1,3-diaminopropane.
The ratio of components (A) to (B) in the addi-
tion products (AB) is chosen such that the ratio of
primary amino groups of (B) to the acrylic and/or
methacrylic double bonds of (A) is from 0.01 : l to
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0.2 : 1. Here, a ratio of from 0.03 : 1 to 0.1 : 1 is
preferred.
The novel addition products (AB) are prepared
by adding the diamines (B) onto an acrylic ester or
methacrylic ester (A) or onto a mixture of these
esters, in a Michael reaction. The amine-modified
oligomers obtained still contain unreacted acrylic
ester and/or methacrylic ester groups and also tertiary
amino groups.
The matting agents (b)
As matting agents (b), use is generally made of
particles of higher dimensional stability, preferably
having a particle size of between 1 and 15 micrometers,
but not more than 50 micrometers, and with a
comparatively narrow particle-size distribution, since
larger particles lead to irregularities in the coating
surface, and having a relatively low density, which
causes the matting agents to float during the film-
forming process in the course of coating.
Preferred matting agents employed are porousphyllosilicates having a large pore volume and a
correspondingly low density. Examples which may be
mentioned of such phyllosilicates are the Syloid~
grades from the company Grace, which have mean particle
sizes of preferably between 1 and 10 micrometers.
It is also possible to employ as matting agents
(b) plastics particles which satisfy the abovementioned
re~uirements. Preference is given to the use of poly-
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~ - 15 -
amide particles, for example Orgasol~ grades from the
company Atochem, which have particle sizes of between 1
and 10 micrometers, a high glass transition temperature
in order to ensure the dimensional stability, and a
large pore volume.
In conjunction with the matting agent it is
preferred to employ paraffin waxes which are added to
the a~ueous coating formulation before the matting
agent is incorporated into it and/or are incorporated
into the coating formulation together with the matting
agent. Such paraffin waxes preferentially coat the
surface of the matting agent particles, leading to a
further reduction in the density of the particles and
to a hydrophobicization of particles.
The re~-ining constituents (d) to (f) 0~ the aqueous
coating materials, the preparation of the aqueous
materials, and their use
The reaction of component (A) with component
(B) to give the addition product (AB) of the binder (a)
can take place before, during or after the formulation
of the aqueous coating material.
In one embodiment of the invention the addition
reaction is carried out in liquid phase prior to coat-
ing formulation, at moderate temperature and in theabsence of a catalyst. The diamine (B) is added in an
appropriate amount to the ester (A) with stirring at
room temperature. During this addition the temperature
may rise to about 40 degrees C. By increasing the
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temperature it is possible to accelerate the reaction;
at 60 degrees C it has subsided after about 12 hours.
The viscosity of the resulting mixture is then constant
over time. For reproducibility, the reaction should
take place as far as possible to completion, which is
achieved at reaction temperatures of above
40 degrees C.
The reaction is generally carried out without solvents,
but it is also possible to employ solvents, in parti-
cular in order to add solid di- and/or polyamines (B)
in solution form. The solvent is then removed after
Michael addition has taken place.
So that no unwanted polymerization takes place during
the addition reaction, polymerization inhibitors are
generally added to the reaction mixture. The suitable
polymerization inhibitors include known products, such
as substituted phenols, such as 2,6-di-tert-butyl-p-
cresol, hydroquinones, such as methylhydroquinones, and
thioethers, such as thiodiglycol or phenothiazine.
In a further embodiment o~ the invention,
component (B) of the binder (a) is added during and/or
after the preparation o~ the aqueous coating formula-
tion consisting of components (a) to (f), the binder
(a) consisting either of component (A) alone or of a
preadduct of components (A) and (B).
In accordance with the invention, in a step
following the addition o~ component (B), the addition
products (AB) of components (A) and (B) are converted
into a water-dilutable form by neutralization, in
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particular of the tertiary amino groups, with at least
one acid.
Acids suitable for neutralizing the basic groups are,
for example, organic acids, such as lactic acid, acetic
acid or formic acid, or mineral acids, such as
phosphoric acid or, preferably, hydrochloric acid.
In addition to the binders described the novel
radiation-curable compositions may additionally com-
prise further photopolymerizable binders, which may
likewise be amine-modified. Suitable such additional
amine-modified binders are, for example, the radiation-
curable binders known from EP-A-0 280 222 and from
US Patents Nos. 4,045,416, 4,547,562 and 4,675,374.
Non-amine-modified additional binders which are suit-
able are, for example, polyether acrylates, polyether
methacrylates, polyester acrylates, polyester meth-
acrylates, urethane acrylates, urethane methacrylates,
epoxy acrylates and epoxy methacrylates.
The fillers and/or pigments (d) which are
present if desired in the novel aqueous coating
materials and which differ significantly from the
matting agents (b), for example in terms of density,
may be inorganic and/or organic materials. Examples of
inorganic fillers and/or pigments which may be
mentioned are: titanium dioxides, carbonates, for
example calcium carbonate or calcium magnesium
carbonate, sulfates, for example barium sulfates (heavy
spar) or potassium sulfates (light spar) or silicates,
for example kaolins, micas or quartz flour. In the case
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- - 18 -
,, .
of the inorganic fillers and/or pigments (d) it should
be considered that the conceptual distinction between
"filler" and "pigment" is often possible only with
difficulty, since substances such as, for example,
barium sulfate or titanium dioxide act simultaneously
as filler and pigment.
As examples of organic fillers and/or pigments,
representative of numerous examples, mention may be
made of: carbon blacks, azo dye pigments or phthalo-
cyanine dye pigments.
As component (e), the radiation-curable aqueous
coating materials if desired include photoinitiators
which are customarily employed in radiation-curable
coating compositions, examples being benzophenones,
benzoins or benzoin ethers, preferably benzophenone in
UV formulations. It is possible to do without the use
of synergists, since the esters present in the coating
compositions are amine-modified and therefore have a
synergistic ef~ect.
The novel radiation-curable aqueous coating
materials include, if desired, customary auxiliaries
and additives (f), examples being antifoams, levelling
agents, film-forming auxiliaries, for example cellulose
derivatives, lubricants, and, in amounts of up to 10%
by weight, solvents, for example methoxypropanol. The
lubricants can be present in the aqueous coating
material in proportions, for example, of from 0.5 to 3%
by weight, the levelling agents in proportions of from
0.2 to 1% by weight, based on the coating material.
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{
In a novel variant the viscosity and reactivity
of the aqueous coating material can be adjusted within
certain limits by adding the amine component (B) prior
to application. If about 48 hours go by between the
addition of the amine component (B) and the application
of the coating composition, the amine (B) is no longer
present in free form but is attached physically or
chemically to the other constituents of the aqueous
coating material, especially of the binder (a). It is
surprising that the reactivity of the coating material
produced with addition of amine increases relative to
the coating formulation described above. Experiments
have revealed that, depending on the amount of amine
(B) added, it is possible to observe an approximately
doubled reaction rate and doubled viscosity under UV
irradiation.
Accordingly, in a pre~erred embodiment of the
invention, the coating material consists of from 95 to
100% by weight, particularly preferably of from 98 to
100% by weight, of the above-described coating
formulation and of from 0 to 5% by weight, particularly
preferably from 0 to 2% by weight, of the amine
component (B). A suitable amine component (B) are [sic]
the compound already described above; that is,
preferably diamines with primary and tertiary amino
groups, particularly preferably dimethylaminopropyl-
amine. As already described above, the addition of the
amine component (B) is followed by the neutralization
of the aqueous coating material with an acid.
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In a further embodiment of the invention a non-
water-soluble precoating material, containing the
components (a), (b), (d), (e) and (f), is formulated
first of all, component (a) in this case being
insoluble in water. The precoating material prepared in
this way is mixed, in a second step, first of all with
the amine component (B) while stirring, preferably at
temperatures between room temperature and 60 degrees C
and for a period of from l to 5 hours, and is then
formulated with the aqueous component (c), containing
an acid to neutralize the amine component, to give the
novel coating material.
The coating compositions can be applied by
spraying, rolling, flow coating, dipping, knife coat-
ing, brushing, pouring or by Vakumat application to thesubstrate, preferably to glass, wood, to wooden
materials or to paper.
The coating films are cured directly following
application or following the evaporation of water which
is present, by means of UV rays or electron beams. The
equipment and conditions for these curing methods are
known from the literature (cf. e.g. R. Holmes, U.V. and
E.B. Curing Formulations for Printing Inks, Coatings
and Paints, SITA-Technology, Academic Press, 10ndon,
United Kingdom 1984, pages 79 to lll), and require no
further description.
The novel coating compositions are also
suitable as printing inks.
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The novel radiation-curable coating composi-
tions exhibit an excellent stability on storage. They
are homogeneous, have good radiation-curability, and
following radiation curing they lead to films having
excellent properties.
The films obtained are additionally notable for an
excellent matt effect (coupled with high film
transparency), which is determined by way of a
reflectometric gloss measurement in accordance with
DIN 67530. The measure of the quality of the matt
effect is the intensity of the reflected light detected
in the course of the gloss measurement - the lower the
intensity, the more pronounced the matt effect.
The novel aqueous coating materials are parti-
cularly suitable as topcoats on glass, wood, paper,plastics or primed substrates of all kinds and can also
be used as primer ~ormulations ~or glass, wood, paper
and plastic.
Below, the invention is illustrated in more
detail with reference to working examples. Parts are by
weight unless specified otherwise.
Examples:
~5 Example 1: Formulation of the aqueous radiation-curable
coating material SL1
The novel aqueous radiation-curable coating
material S~1 is prepared by mixing the components:
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(a) 58.00 parts of polyether acrylate, prepared from
Polyol PP150 from the company
Perstorp and acrylic acid,
(b) 12.00 parts of phyllosilicate Syloid ED 50 from
the company Grace as matting agent,
(c) 24.40 parts of water,
(e) 3.00 parts of benzophenone, and
(f) 2.00 parts of lubricant (Lanco Wax 1362D from the
company Langer & Co.) and
0.60 parts of antifoam (Byk 022 from the company
Byk)
Example 2: Formulation of the aqueous radiation-curable
coating material SL2
The novel aqueous radiation-curable coating
material SL2 is prepared by mixing the components:
(a) 43.77 parts of a mixture of 98.2% by weight of
polyether acrylate, prepared from
polyol Desmophen 550U from the
company Bayer and acrylic acid and
1.8% by weight of N,N-dimethyl-1,3-
diaminopropane,
20.47 parts of polyether acrylate, prepared from
Polyol PP150 ~rom the company
Perstorp and acrylic acid,
(b) 10.94 parts of phyllosilicate Syloid ED 50 from he
company Grace as matting agent,
(c) 16.21 parts of aqueous 1% strength hydrochloric
acid,
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(e) 3.44 parts of benzophenone, and
(f) 5.16 parts of methoxypropanol.
Example 3: Formulation of the aqueous radiation-curable
coating material SL3
The novel aqueous radiation-curable coating
material SL3 is prepared by mixing the components:
(a) 58.00 parts of polyether acrylate, prepared from
Polyol PP150 from the company
Perstorp and acrylic acid,
(b) 11.50 parts of phyllosilicate Syloid ED 50 from
the company Grace as matting agent,
(c) 22.50 parts of water,
(e) 3.00 parts of benzophenone, and
(f) 2.00 parts of surface auxiliary (Lanco Wax 1362D
from the company Langer & Co.),
2.50 parts of surface auxiliary (Talkum Steamic
OOS from the company Grolmann) and
0. 50 parts of thickener (Aerosil R972 from the
company Degussa AG).
Example 4: Production of a water-compatible coating
material SL4 from a nonwater-compatible pre-
2 5 coating material
The precoating material is prepared by mixing
the components:
(a): 58.00 parts of polyether acrylate (Laromer P033f
from the company BASF AG),
CA 02239310 1998-06-02
- (b): 12.00 parts of phyllosilicate Syloid ED 50 from
the company Grace as matting agent,
(e): 3.00 parts of benzophenone (Irgacure 500 from
the company Ciba), and
(f): 2.00 parts of surface auxiliary (Lanco ~ax 1362D
from the company Langer & Co.),
0.30 parts of antifoam (Byk 022 from the company
Byk) and
0.30 parts of antifoam (Byk 024 from the company
Byk).
Following the preparation of the precoating
material, first of all 2.00 parts of N,N-dimethyl-1,3-
diaminopropane are added, then the mixture is stirred
at room temperature for 3 hours, and finally
15 24.40 parts of an aqueous 3% strength hydrochloric acid
are added.
The result is a homogeneous coating material SL4 which,
on application, like coating materials SL1, SL2 and
SL3, leads to a uniform coating.
C~ ,~~ison Example:Dispersion of the precoating
material in water or in aqueous 3%
hydrochloric acid without producing
compatibility in water (coating
material VL1)
A precoating material is first of all prepared
in accordance with Example 4, and then 26.40 parts of
water or, respectively, aqueous 3% strength hydro-
chloric acid are added to it.
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!
The result is a nonhomogeneous coating material VL1
which on application leads to a nonuniform coating.
Example 5: Gloss measurements on coatings with the
coating materials SL1, SL2, SL3, SL4 and VL1
The gloss measurements are carried out by
reflectometry at an angle of 60 degrees in accordance
with DIN 67 530, the measure used for the gloss being
the units (E) of the meter connected to a photoelectric
receiver on which the reflected light flux is incident.
Matt effects which appear visually good occur at values
below 60 E (silk matt effect 40 to 50 E), and
particularly good matt effects below 30 E. The coating
materials investigated were the novel coating materials
SL1, SL2, SL3, SL4 and the comparison coating material
VLl on the substrates polyvinyl chloride PVC (plastic),
glass and cherry wood KBH. In the case of the coating
of cherry wood KBH, the wood was first of all primed
(GR) with the coating material SL3 and then topcoated
(DL) with the coating materials SL1 and SL2. The film
thicknesses of the coating film resulting after coating
and curing are indicated in brackets in each case.
The coatings were cured under an 80 watt mercury UV
source. In the case of such lamps, energy inputs of
25 from 100 to 250 mJ/cm2 are typically customary.
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<
Coating Gloss measurement /E (film thickness of the
material paint in micrometers) on
Glass PVC KBH
SL1 18 (20)10 (12) 10 (10 DL)
SL2 20 (20)16 (12) 12 (10 DL)
SL3 18 (20)13 (12) 18 (10)
SL4 30 (20)9 (12)
VL1 81 (20)45 (12)
