Note: Descriptions are shown in the official language in which they were submitted.
- 1~ ?l2sssl
.
PROCESS FOR THE PREPAR~TION OF COPOLYMERS CONTAINING OH-
GROUPS, AND THEIR USE IN HIGH-SOLIDS COATING COMPOSITIONS
Background of the Invention
The present invention relates to copolymers for use
in high-solids coating composition, and to a process for
preparation of such copolymers.
An advantage of high-solids acrylate resins coating
formulations is that they have a reduced emission of
organic compounds when the coating material is applied.
In order to obtain these high-solids coating formulations
it is necessary to employ appropriate acrylate resins
having low viscosities, i.e., low molar masses, and
having narrow molar mass distributions.
It is well known that in order to prepare low-
viscosity polymers it is possible to emp]oy free-radical
solution polymerization. See EP 408,858, EP 398,387, and
U.S. Patent 4,145,513. The disadvantage of this process
is that the properties of the polymers are adversely
affected by use during the process of considerable
quantities of polymerization initiators and
polymerization regulators. In addition, the production
of secondary products, some of which are not incorporated
into the polymer chain is disadvantageous. Also, the
polymerization regulators used, for example, thiols, can
have a foul odor or may even be toxic.
The polymers obtained by free-radical solution
polymerization at high pressure and/or at high
temperature in high-boiling solvents do not have these
disadvantages but, because of their inadequate molar
masses, they have glass transition temperatures which are
too low to permit their use as binders for coating. This
becomes evident in the coatings by these materials having
dust-dry times and tack-free drying times which may be of
indeterminate length. In addition, some systems have a
processing time which is inadequate for commercial
application.
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-- 2
; On the other hand, bulk polymerization is also
known. The great advantage of a bulk polymerization is
that only monomer, polymer and initiator are present in
the reaction mixture with the consequence that highly
pure, solvent-free products are formed. In practice,
7 examples of such bulk polymerization are few, because the
liberation of very large quantities of heat in a short
reaction time means that the polymerization is difficult
to control.
EP o 027 931 describes such a process for the
preparation of low-viscosity copolymers, containing OH
groups, by free-radical reaction of (A) from 10 to 30% by
weight of glycidyl esters, containing 12 to 14 carbon
atoms, of aliphatic saturated monocarboxylic acids having
a tertiary or quaternary ~ carbon atom and (B) from 90 to
70~ by weight of at least two unsaturated copolymerizable
monomers, at least one of which contains at least one
COOH group.
The process comprises initially charging component
(A) and reacting it, at 130 to 200C, with component (B)
and a free-radical initiator by bulk polymerization until
a degree of conversion of at least 95~, preferably at
least 98~, has been reached, component (B) containing at
least 3.3% by weight of a monomer containing COOH groups.
The principal advantage of this process is in the
efficient and rapid dissipation of the heat of reaction,
during the reaction, by employing component (A) as
initial charge. Component (A), the glycidyl ester, acts
initially as a solvent and is incorporated completely
into the copolymerization product during the reaction, so
that no troublesome unreacted components remain present
in the end product.
Most organic peroxides, especially those derived
from ~ertiary t-butyl hydroperoxides and used in the
examples of the above-mentioned patent, have a very high
reactivity which results from the corresponding radicals.
The free radicals derived from hydroperoxides of the
t-butyl type, especially di-t-butyl peroxide, are able to
abstract hydrogen from the acrylate polymer, which may
.
_ 3 _ 2l285sl
lead to instances of branching and therefore to a
broadening or multimodality in the molar mass
distribution. This is observed for the products in
j EP 0 027 931. By this process the solution viscosities
;~ 5 of the products are increased. These effects occur
preferentially in interaction with the solvents and
solvent mixtures which are conventionally used.
It is known that, in solution polymerizations, high-
solids acrylate polymers of monomodally narrow
distribution can be prepared by using organic peroxides
which are derived from t-amyl hydroperoxide [V.R. Kamath
and J.D. Sargent Jr., Paintindia 41 (1), 17-22 (Eng.)
1991; P.A. Callais, V.R. Kamath and M.G. Moskal, "Proc.
Water-Borne, Higher-Solids, Powder Coat. Symp." (New
Orleans), l9th, 156-70 (Eng.) 1992]. However, there is
no indication that acrylate polymers of this kind can be
prepared with this initiator system even without the
presence of a solvent.
Summary of the Invention
Therefore, an object of the present invention is to
provide a bulk copolymerization process which provides
solvent-free, low-viscosity acrylate resin polymers of
monomodally narrow distribution, which can be carried out
within a broad temperature range. It is also an object
of the invention to provide a copolymer having these
desired properties and coating compositions containing
these desired copolymers.
In accordance with these objects, there has been
provided a copolymer having an OH number of from 50 to
250mg KOH/g, a solution viscosity (50~ strength, 23C) of
15 to 2000 mPa.s, a weight average molar mass Mw f less
than 8600 g/mol and a polydispersity of less than 3.4.
In accordance with a second aspect of the invention,
there has been provided a copolymer of
(A) one or more glycidyl esters of saturated
aliphatic monocarboxylic acids having a
tertiary or quaternary ~ carbon atom, and
"
21285S~ ' .
(B) at least two unsaturated copolymerizable
monomers, one of which at least contains at
least one COOH group
wherein the polymer has a low viscosity in solution and
a monomodal, narrow molar mass distribution.
In accordance with a third aspect of the present
invention, there has been provided a copolymer of
(A) from 5 to 50% by weight of one or more
glycidyl esters of saturated aliphatic
10monocarboxylic acids having a tertiary or
quaternary ~ carbon atom which acids contain
from 4 to 30 carbon atoms, and
(B) from 95 to 50% by weight of at least two
unsaturated copolymerizable monomers, one of
15which at least contains at least one COOH
group.
In accordance with another aspect of the present
invention there has been provided a process for producing
a copolymer as set forth above, comprising the free-
20radical reaction in bulk of components (A) and (B).
In accordance with another aspect of the present
invention, there has been provided coating compositions
comprising a copolymer as described above and a substrate
coated with such a composition.
25Further objects, features, and advantages of the
present invention will become apparent from the detailed
description of preferred embodiments which follows.
Detailed Description of the Preferred Embodiments
The invention relates to acrylate copolymers which
30have a low viscosity in solution and have a monomodal,
narrow molar mass distribution. By a low viscosity is
meant a viscosity of less than 2 Pa.s, measured on a 50 %
strength solution at 23 C and by a monomodal, narrow
molar mass distribution is meant a polydispersity of less
35than 3.4. The copolymers generally have an OH number of
from 50 to 250 mg of KOH/g, a low solution viscosity of
from 15 to 2000 mPa.s (50% strength, 23C), a weight
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2l285~l
average molar mass Mw of less than 8600 g/mol and a
polydispersity MW/Mn [weight-average molar mass over
number-average molar mass] of less than 3.4. By means of
the process described herein, such copolymers are
obtainable for the first time.
These low-viscosity, uniform, OH group-containing
copolymers of monomodally narrow distribution can be
prepared by the free-radical reaction of
(A) one or more glycidyl esters of saturated
aliphatic monocarboxylic acids containing a
tertiary or quaternary ~ carbon atom, and
(B) at least two unsaturated copolymerizable
monomers, one of which at least contains at
least one COOH group.
Advantageous products in the context of the
invention are obtained in particular by the free-radical
copolymerization of
(A) from 5 to 50 %, preferably 7 to 45 %, more
preferably 9 to 40 % by weight of glycidyl
esters, of aliphatic saturated monocarboxylic
acids containing 4 to 30 carbon atoms and
containing a tertiary or quaternary ~ carbon
atom and
(B) from 95 to 50 %, preferably 93 to 55 %, more
preferably 91 to 60 % by weight of at least
two unsaturated copolymerizable monomers, one
of which at least conta.ins at least one COOH
group,
wherein component (A), the glycidyl ester, is initially
charged and reacted, preferably at from 100 to 210C,
preferably 120 to 200 C, with component (B) and at least
one specific free-radical initiator, by bulk
polymerization, until a degree of conversion of at least
95%, preferably at least 97.5%, has been reached. It is
also preferred that component (B) contain at least 3.0%
by weight of a monomer containing COOH groups.
The monomers containing COOH groups are preferably
available in a quantity such that the reaction with
component (A) proceeds to completion and results in an
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acid number of at least 2 mg of KOH/g, preferably 3 to
15, in the product prepared.
To produce the copolymers of the invention,
specific, free radical-forming peroxy compounds are
suitable as polymerization initiators. These specific
peroxy initiators possess at least one tertiary carbon
atom which is adjacent to the peroxy group and carries
three linear or branched alkyl or aralkyl groups, at
least one of which possesses more than 1 carbon atom.
Compounds of this kind are described by the formula
Rl-O-O-R2 ~
where
R1 is hydrogen, a linear or branched aliphatic acyl
radical of 2 to 15 carbon atoms or R2, and
R2 satisfies the formula
- C - R4
R5
R3 is a linear or branched alkyl or aralkyl radical of
at least 2 carbon atoms, and
R4 and R5 are identical or different and are a linear or-
branched alkyl or aralkyl radical of 1 to 15 carbon
atoms. ~
Examples of such peroxy compounds are t-amyl peroxy- ;
2-ethylhexanoate, 1,1-di(t-amylperoxy)cyclohexane, t-amyl
peroxyacetate, ethyl 3,3-di(t-amylperoxy)butyrate,
di-t-amyl peroxide, 3-ethylpent-3-yl peroxy-2'-ethyl-
hexanoate and di(3-ethylpent-3-yl) peroxide.
The proportion of initiator may be varied to give
the desired product, and is, for example, from 0.5 to 5%
by weight, preferably 0.5 to 4% by weight and in
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particular 0.5 to 3% by weight, based on the total weight
of the starting components.
As component (A) any desired glycidyl ester can be
used. Glycidyl esters of ~-alkylalkanemonocarboxylic
acids and/or ~ dialkylalkanemonocarboxylic acids are
preferably used, alone or as a mixture. The
~-alkylalkanemonocarboxylicacidsand~,~-dialkylalkanoic
acids are isomer mixtures of the corresponding
monocarboxylic acids containing 4 to 30, preferably 5 to
20 carbon atoms.
Component (B) is a mixture of at least two kinds of
olefinically unsaturated copolymerizable monomers, at
least one of which contains a carboxyl group. Any
combination of monomers having these characteristics can
be used.
Examples of suitable olefinically unsaturated acidic
monomers in the case of component (B) include acrylic
and/or methacrylic acid and/or monoesters of maleic,
fumaric or itaconic acid, maleic acid, fumaric acid,
itaconic acid themselves and crotonic, isocrotonic and
vinylacetic acid, and also unsaturated fatty acids of 8
to 22 carbon atoms, for example, linolenic acid, linoleic
acid, oleic acid, arachidonic acid and ricinenic acid.
Examples of suitable olefinically unsaturated
monomers without carboxyl groups include acrylic and/or
methacrylic esters of monohydric alcohols of 1 to 20
carbon atoms and the hydroxyalkyl esters of these acids,
and also acrylonitrile. Particularly suitable acrylic
esters are, for example, the methyl, ethyl, propyl,
2-ethylhexyl, butyl, isobutyl, tert-butyl, hexyl, nonyl,
lauryl and stearyl esters of acrylic and methacrylic
acid.
Examples of other useful monomers include
hydroxyalkyl esters of ~,~-unsaturated carboxylic acids
containing a primary hydroxyl group such as hydroxyethyl
acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate,
hydroxyamyl acrylate, hydroxyhexyl acrylate, hydroxyoctyl
acrylate and the corresponding methacrylates. Examples
of hydroxyalkyl esters containing a secondary hydroxyl
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2128~51
group which can be used are 2-hydroxypropyl acrylate,
2-hydroxybutyl acrylate, 3-hydroxybutyl acrylate,
trimethylolpropane diacrylate and the corresponding
methacrylates. It is also possible to employ the
corresponding esters of other ~,~-unsaturated carboxylic
acids, for example, those of crotonic acid and of
isocrotonic acid. Particular preference is given to
hydroxyethyl, hydroxypropyl and hydroxybutyl acrylates
and methacrylates. Other suitable monomers are the
products of reaction of one mole of hydroxyethyl acrylate
and/or hydroxyethyl methacrylate and on average two moles
of ~-caprolactone.
other suitable olefinically unsaturated monomers
include vinyl-aromatic hydrocarbons such as styrene,
(alkylphenyl)ethenes, e.~ -methylstyrene,
~-chlorostyrene and the various vinyltoluenes.
In the initial monomer mixture, component (B)
preferably comprises a mixture of
(B1) from 3.3 to 20% by weight, preferably from 3.3
to 15% by weight, of an ~,~-unsaturated
monocarboxylic acid, preferably acrylic or
methacrylic acid or mixtures thereof,
(B2) from 0 to 43% by weight, preferably from 16 to
43% by weight, of a hydroxyalkyl ester of
acrylic acid or methacrylic acid or mixtures
thereof,
(B3) from 0 to 57% by weight, preferably from 5 to
45% by weight, of an ester of acrylic or
methacrylic acid with a monohydric alcohol of
1 to 20 carbon atoms, or mixtures thereof,
(B4) from 0 to 72% by weight, preferably from 15 to
55% by weight, of at least one aromatic vinyl
compound,
the sum of components (B) always being 100 and the sum of
the esters (B2) and (B3) preferably being not more than
85% by weight.
During the polymerization reaction, the acidic
monomers and the initial charge of glycidyl ester react
to form a product which is present in the copolymer
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obtained in accordance with the invention, in general, in
a proportion of from 6 to 60% by weight, preferably from
10 to 55% by weight.
The polymerization is preferably carried out as a
bulk polymerization. The term "bulk polymerization"
refers to a polymerization which is generally carried out
without solvents. In some cases, however, the presence
of a small proportion of solvent, namely up to 20% by
weight, preferably up to 10 and in particular up to 8% by
weight, based on the starting components, is also
possible. However, working without solvent is preferred.
By working without solvent, solvent-solute
interactions can be excluded which generally lead to
chemical non-uniformity in copolymers.
A particularly preferred procedure is one in which,
initially, at least one component (A) is initially
charged at the beginning of the polymerization and,
subsequently, at least two unsaturated copolymerizable
monomers (B) are added, at least one of which contains a
COOH group. Component (A) is preferably completely
incorporated into the copolymer during the
polymerization. This is effected by ring-opening
esterification of the glycidyl groups in component A and
the carboxylic acid groups in component B.
The hydroxyl group-containing copolymers of the
present invention can be further modified in a subsequent
step, for example by reacting them with isocyanate
compounds which, for example, which contain per molecule
on average from 0.8 to 1.5 free NCO groups and at least
one tertiary amino group. In this case, the solvent
employed in the polymerization, i.e., the preparation of
the polymers, should be inert with respect to these
isocyanat~ compounds.
These isocyanate compounds also include, for
example, all low molecular weight urea derivatives which,
in the paint industry, lead to "sag controlled" acrylate
reslns.
The polymers according to the invention can be
identified by their content of OH groups. They generally
2 1 2 ~
-- 1 o
; have an OH number of from 50 to 250 mg of KOH/g,
preferably from 80 to 200 and in particular from 90 to
180 mg of KOH/g. Furthermore, the polymers possess a
~;. particularly low solution viscosity. This viscosity is
Q 5 generally in the range from 15 to 2000 mPa.s, preferably
from 20 to 700 and in particular from 25 to 500 mPa.s
(measured for a 50% strength solution in butyl acetate or
in a mixture of 3 parts of butyl acetate and 4 parts of
xylene at 23C in accordance with DIN 53 018). The
polymers according to the invention generally possess
weight average molar masses of less than 8600 g/mol,
preferably less than 8500 g/mol, and a polydispersity of
less than 3.4, in particular less than 3.2, especially
preferred, less than 3.1.
One of the essential differences between a synthetic
high polymer and a monomeric substance is the fact that
it is not possible to assign a polymer an exact molar
mass. This is a consequence of the length of the chain
formed during polymerization reactions being determined
solely by random events. Because of the random nature of
the growth process, it is unavoidable that chains of
different length will be formed; in other words, there
will be a distribution of chain lengths.
Gel permeation chromatography (abbreviated as GPC)
has in recent years become a frequently used method for
;$ determining molar masses and their distributions. This
method, which is usually calibrated using polystyrene,
yields a number-average Mn and a weight-average Mw molar
mass. The breadth of the distribution can often be
' 30 estimated by calculating the polydispersity MW/Mn. The
nearer this quotient is to 1, the more physically uniform
; is the polymer. Polymers of greater uniformity, such as
the copolymers of the present invention, from the
l coatings technology point of view, have advantages in
j 35 terms of drying and hardness.
'! The copolymers according to the invention are
particularly suitable for coatings applications in
2-component systems, especially for so-called high-solids
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systems: i.e., for solvent-containing mixtures with a
high solids content.
Examples of suitable solvents for eoating using the
eopolymer obtained in aecordance with the invention
inelude any known solvents and particularly are
aliphatic, cycloaliphatic and/or aromatic hydrocarbons,
such as alkylbenzenes, for example, xylene or toluene;
esters, such as ethyl acetate, butyl acetate, acetates
with longer alcohol residues, butyl propionate, pentyl
propionate, ethylene glycol monoethyl ether acetate, the
eorresponding methyl ether acetate; ethers, such as
ethylene glycol acetate monoethyl, monomethyl or
monobutyl ether; glycols; alcohols; ketones, such as
methyl amyl ketone or methyl isobutyl ketone; lactones,
or the like, as well as mixtures of these solvents.
The present invention relates furthermore to eoating
compositions which eontain the eopolymers aeeording to
the invention as a binder eomponent. The eopolymers may
be eured in the presenee of suitable erosslinking agents
without heat or at elevated temperature. Any desired
crosslinkers can be used.
Suitable curing components in these eoating
eompositions are amino resins, polyisoeyanates or
eompounds which contain anhydride groups, alone or in
eombination. Generally, the erosslinking agent is added
in a quantity sueh that the molar ratio of the OH groups
of the eopolymer to the reaetive groups of the
erosslinking agent is between 0.3:1 and 3:1.
Amino resins whieh are suitable as the euring
eomponent are preferably urea, melamine and/or
benzoguanamine resins. These are etherified condensation
produets of urea, melamine or benzoguanamine with
formaldehyde. Suitable mixing ratios generally are in
the range from 50:50 to 90:10 in terms of eopolymer/amino
resin erosslinking agent, based on solid resin.
Appropriate phenolie resins and their derivatives also
ean be employed as euring agents. In the presenee of
aeids, for example, p-toluenesulfonie aeid, these
erosslinking agents lead to full euring of the eoating.
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Heat curing can be undertaken conventionally at
temperatures of from 90 to 200C over, for example, from
10 to 30 minutes.
Polyisocyanates are suitable for curing the products
according to the invention accompanied by crosslinking,
especially at moderate temperatures (lO to 80 C) or at
room temperature. Suitable polyisocyanate components
are, in principle, all aliphatic, cycloaliphatic or
aromatic polyisocyanates which are known from
polyurethane chemistry, alone or in the form of mixtures.
Particularly suitable examples are low molecular weight
polyisocyanates such as, for example, hexamethylene
diisocyanate, 2,2,4- and/or 2,4,4-trimethyl-
1,6-hexamethylene diisocyanate, dodecamethylene
diisocyanate, tetramethyl-p-xylylene diisocyanate,
1,4-diisocyanatocyclohexane, 1-isocyanato-
3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI),
2,4'- and 4,4'-diisocyanatodicyclohexylmethane, 2,4'-
and/or 4,4'-diisocyanatodiphenylmethane or mixtures of
these isomers with their higher homologs, as are
accessible in a manner known per se by phosgenization of
aniline/formaldehyde condensation products, and also 2,4-
and/or 2,6-diisocyanatotoluene, or any mixtures of such
compounds.
Derivatives of these simple polyisocyanates are
preferably employed, as are conventional in coating
technology. These include polyisocyanates which contain,
for example, biuret groups, uretdione groups,
isocyanurate groups, urethane groups, carbodiimide groups
and/or allophanate groups, as are described, for example,
in EP 0 470 461 which is hereby incorporated by
reference.
The particularly preferred modified polyisocyanates
include N,N',N"-tris(6-isocyanatohexyl)biuret and its
mixtures with its higher homologs, as well as
N,N',N"-tris(6-isocyanatohexyl) isocyanurate and its
mixtures with its higher homologs containing more than
one isocyanurate ring.
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The crosslinking can be catalyzed by adding an
organometallic compound, such as a tin compound and, if
desired, a tertiary amine, preferably
diethylethanolamine. Examples of appropriate tin
compounds are dibutyltin dllaurate, dibutyltin diacetate
and dibutyloxotin. Compounds suitable for curing at
elevated temperature, in addition, include blocked
polyisocyanates, polycarboxylic acids and their
anhydrides.
The copolymers according to the invention are
particularly suitable for the production of high-solids
(i.e. more than 50 % solids content), solvent-containing
clearcoats. In addition, they are well-suited to
producing powder coatings, particularly in conjunction
with polycarboxylic anhydrides. The copolymers can be
employed for reaction with polycarboxylic anhydrides and
for the subsequent use of the resulting products as
curing agents for various synthetic resins, especially
epoxy resins. The use of the copolymers according to the
invention by reaction with specific partial esters of
polycarboxylic acids, or with derivatives of
polycarboxylic acids or their anhydrides or ester
anhydrides, is of particular interest.
Examples of preferred polycarboxylic acid
derivatives are polyanhydrides derived from at least
tetrahydric carboxylic acids, with which polyanhydrides
the products according to the invention can be reacted.
These systems are of particular advantage for cold
curing, because of their high reactivity.
In coating compositions prepared using the
copolymers according to the invention it is also possible
for other auxiliaries and additives, conventional in
coating technology, to be present, although not mentioned
hitherto. These include, in particular, catalysts,
levelling agents, silicone oils, plasticizers such as
phosphates and phthalates, pigments such as iron oxides,
lead oxides, lead silicates, titanium dioxide, barium
sulfate, zinc sulfide, phthalocyanine complexes, and the
like, and fillers such as talc, mica, kaolin, chalk,
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ground quartz, ground asbestos, ground slate, various
silicic acids, silicates etc., viscosity-controlling
additives, flattening agents, W absorbers and light
stabilizers, antioxidants and/or peroxide scavengers,
antifoams and/or wetting agents, active diluents and the
like.
The coating compositions can be applied to the
respective substrate by any known methods, for example by
brushing, dipping, flow coating or using rollers or
blades, but in particular by spraying. They may be
applied under heated conditions and, if desired, can be
brought into a form in which they are ready for
application by the injection of supercritical solvents
(e.g., C02).
Automotive refinishes with excellent properties can
be obtained with binders prepared using the copolymers
according to the invention. These binders can be
employed for the preparation of both intermediate coats
and pigmented or unpigmented topcoats. Express reference
is made to the preferential suitability of these binder
combinations in two-component automotive refinishes. For
this purpose the coating materials are generally cured
within the temperature range from -20 to +100C,
preferably from -10 to +60C.
The invention is illustrated in more detail in the
examples which follow. In the embodiment examples, all
percentages are by weight.
Examples:
1.) Preparation of the copolymers
In a reactor fitted with a stirrer, inert gas inlet,
a heating and cooling system and an addition device, the
glycidyl ester of an ~,~-dialkylalkanemonocarboxylic acid
[e.g., glycidyl ester of Versatic 10 acid (trade name
CarduraO E 10, Shell Chemicals)] (in some cases with
solvent or solvent mixtures) is initially charged and
heated to the desired temperature under inert gas.
Subsequently, over a period of 6 hours, the monomer
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mixture (in some cases with solvent or solvent mixtures)
is metered in at a uniform rate, together or separately,
with the specific initiator (in some cases in solvent or
solvent mixtures). Polymerization is subsequently
carried out for 2 hours until a conversion of at least
95% has been reached.
The copolymers are dissolved in suitable solvents or
solvent mixtures.
The following copolymers are prepared. The precise
batches in terms of parts by weight, reaction conditions
and product characteristics can be taken from the tables
which follow.
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Table 1: Preparation and properties of copolymers A
Mixture (parts) Comparison 1 2
Organic compounds
Glycidyl ester 13.03 13.03 13.02
5Acrylic acid 4.14 4.14 4.14
Hydroxyethyl methacrylate 28.08 28.08 28.08
Methyl methacrylate 7.58 7.58 7.58
Styrene 47.17 47.17 47.17
Initiator A 8 C
di-t-butyl t-a~,yl peroxy- di-t-a~,yl
peroxide 2-ethylhexanoate peroxide
1.51 2.47 1.84
Polymerization temperature
(oC) 185 185 185
15SC (%) after polymerization98.4 98.2 97.9
SC (%) SF (in butyl acetate) 70.3 69.4 70
Acid number (mg KOH/g SR) 8.1 5.9 5.8 :
Hydroxyl number (mg KOH/g SR) 143 140 136
Viscosity (mPa.s), 23C (SF)10820 8300 4440
20Viscosity (mPa.s), 23C
(50% strength in BuAc/xylene 3:4) 177 145 106
GPC (PS calibration)
Mw (g/mol) 8700 6830 5450
Mn (g/mol) 2560 2530 2260
U = ~/~ 3.4 2.7 2.4
Hazen color number
(Lovibond) 100 90 100
Appearance transF~rent trans,oarenttrar6parent
SC: Solids content
SR: Solid resin
SF: Supply form
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Initiators:
A di-t-butyl peroxide: Trigonox~ B (AKZO)
B t-amyl peroxy-2-ethylhexanoate: Trigonox~ 121 (AKZO)
C di-t-amyl peroxide: Interox~ DTAP (Peroxid-Chemie)
5 GPC: Mw~ Mn Millipore~ Waters Chromatography System
860
Pump: Waters model 590, RI detector: Waters model 410
Column packing: Waters Ultrastyragel 1 x 1000 A +
1 x 500 A -~ 1 x loo A
(Angstrom)
Solvent: tetrahydrofuran at 40C
- Flow rate: 1 ml/min, concentration: 1~ based on solids
content
Calibration: polystyrene (PSS, Mainz) ~ .
15 Determination of characteristics: Acidnumker,hydroxyl ~m~er ~ -
and viscosity (for standards see "Analytische
Bestimmungsmethoden" ~Analytical determination methods]
(brochure: Synthetic resins Hoechst AG, 1982 edition)). Hazen
color number Lovibond) according to DIN 53 409. - .
The copolymers A1 and A2 prepared have relatively low
weight-average molar masses. The gel permeation
chromatograms show no high molar mass "shoulders", which
is evident in a relatively low nonuniformity.
In accordance with the lower molar masses and the
higher degree of uniformity, there is a reduction in the ~ .
supply form viscosity as measured in an Ubbelohde
viscosimeter.
.: . . ' ' ' ~ :
2128~51
"
- 18 -
Table 2: Preparation and properties of copolymer~ B
Mixture (parts) Comparison 1 . 2
Oryanic compounds
Glycidyl ester 19. 70 19.70 19.70
5Acrylic acid 6.87 6.87 6.87
Hydroxyethyl methacrylate16.26 16.26 16.26
Methyl methacrylate 24.34 24.34 24.34
Styrene 32.83 32.83 32.83
Initiator _ B
0 di-t-~tylt-ar,yl peroxy- di-t-ranyl
peroxide2-ethylhex~noateperoxide
1.50 2.41 1.7
Polymerization temperature
(C) 160 160 160
15SC (%) after polymerization 98.5 97.6 98.8
SC (%) SF (in butyl aeetate) 70.4 69.7 69.8
Aeid number (mg KOH/g SR) 13.0 11.2 10.8
Hydroxyl number (mg KOH/g SR) 112 115 110
Viseosity (mPa.s), 23C (SF) 13540 10650 9130
20Viseosity (mPa.s), 23C
(50% strength in B~Ac) 172 137 118
GPC (PS ealibration)
(g/mol) 11750 8440 7870
Mn (g/mol) 3180 2910 2890
25U = ~/Mn 3.7 2.9 2.7
Hazen eolor number
(Lovibond) 150 80 80
Appearance trr~rent tr~rent tr~rer,t
r~ 21 2 8 ~ ~1
-- 19 --
Initiators:
A di-t-butyl peroxide: Trigonoxf~ B (AKZO)
B t-amyl peroxy-2-ethylhexanoate: Trigonoxf~ 121 (AKZ0)
C di-t-amyl peroxide: Interox~ DTAP (Peroxid-Chemie)
5 GPC: Mw, Mn Millipore~ Waters Chromatography System
860
Pump: Waters model 590, RI detector: Waters model 410
Column packing: Waters Ultrastyragel 1 x 1000 A +
1 x 500 A + 1 x l o o A
(Angstrom)
Solvent: tetrahydrofuran at 40C
Flow rate: 1 ml/mln, concentration: 1% based on solids
content
Calibration: polystyrene (PSS, Mainz)
Determination of characteristics: Acidnumber, hydroxylnumber
and viscosity (for standards see "Analytische
Bestimmungsmethoden" [Analytical determlnation methods~
(brochure: Synthetic resins Hoechst AG, 1982 edition)). Hazen
color number Lovibond) according to DIN 53 409.
The copolymers B1 and B2 prepared have relatively low
weight-average molar masses. The gel permeation
chromatograms show no high molar mass "shoulders" which
is evident in a relatively low nonuniformity.
In accordance with the lower molar masses and the
higher degree of uniformity, there is a reduction in the
supply form viscosity as measured in an Ubbelohde
viscosimeter.
- 2o 2l2~
Table 3: Preparation and properties of copolymers C
Mixture (parts) Comparison 1 2
Glycidyl ester 20.71 20.71 20.71
Aerylic acid 6.19 6.19 6.19
5Hydroxyethyl methaerylate 13.30 13.30 13.30
Methyl methaerylate 21.02 21.02 21.02
Styrene 38.78 38.78 38.78
* with a very s~all amount of solvent: butyl aeetate
Initiator A B C
di-t-butylt-anyl peroxy- di-t-anyl
peroxide2-ethylhex~oateperoxide
1.50 2.36 1.79
Polymerization temperature
(C) 185 185 185
15SC (%) after polymerization 97.2 97.9 98.0
SC (%) SF (in butyl acetate) 69.4 70.8 70.5
Aeid number (mg KOH/g SR) 4.5 3.4 3.1
Hydroxyl number (mg KOH/g SR) 111 106 108
Viseosity (mPa.s), 23C (SF) 7620 4810 2790
20Viseosity (mPa.s), 23C
(50% strength in BuAc) 135 71 48
GPC (PS calibration)
Mw (g/ l) 8920 5480 3600
Mn (g/mol) 2550 2430 1710
25 U = Mw/~ 3.5 2.3 2.1
Hazen color number
(Lovibond) 70 80 40
Appearance tr~r~t tr~rent tr~q~rent
,,.~ , -. : .: :
,......... . . .
21285~
- 21 -
Initiators:
A di-t-butyl peroxide: Trigonox~ B (AKZO)
B t-amyl peroxy-2-ethylhexanoate: Trigonox~ 121 (AKZO)
C di-t-amyl peroxide: Interox~ DTAP (Peroxid-Chemie)
5 GPC: M~, Mn Mi l l ipore~ Waters Chromatography System
860
Pump: Waters model 590, RI detector: Waters model 410
Column packing: Waters Ultrastyragel 1 x 1000 A +
1 x 500 A + 1 x loo A
(Angstrom)
Solvent: tetrahydrofuran at 40C
Flow rate: l ml/min, concentration: 1% based on solids
content
Calibration: polystyrene (PSS, Mainz)
15 Determination of characteristics: Acidnumber,hydroxylnumker
and viscosity (for standards see "Analytische
BestimmNngsmethoden" [Analytical determination methods]
(brochure: Synthetic resins Hoechst AG, 1982 edition)). Hazen
color number (Lovibond) according to DIN 53 409.
The copolymers C1 and C2 prepared have relatively low
- weight-average molar masses. The gel permeation
chromatograms show no high molar mass "shoulders", which
is evident in a relatively low nonuniformity.
In accordance with the lower molar masses and the
higher degree of uniformity, there is a reduction in the
supply form viscosity as measured in an Ubbelohde
viscosimeter.
~,:. .: - -
,.. ~ . . -
, , 21285~1
- 22 -
Table 4: Preparation and properties of copolymers D
Mixture (parts) C ~ arison 1 2
Glycidyl ester 9.51 9.51 9.51
Acrylic acid 3.03 3.03 3.03
5Hydroxyethyl methacrylate24.87 24.87 24.87
Methyl methacrylate 27.20 27.20 27.20
Styrene 35.39 35.39 35.39
with a very small amount of solvent: butyl acetate
Initiator A B C
di-t-hltylt-aJryl peroxy- di-t-anyl
~eroxide2-ethylhexEr~ateperoxide
1.10 1.73 1.31
Polymerization tem~erature
~L 175 175 175
15SC (%) after polymerization 98.2 98.9 98.6
SC (%) SF tin butyl acetate) 69.0 69.4 69.5
Acid number (mg KOH/g SR) 5.2 4.5 4.3
Hydroxyl number (mg KOH/g SR) 129 116 129
Viscosity (mPa.s), 23C (SF)18210 15840 6840
20Viscosity (mPa.s), 23C
(50% strength in BuAc) 253 182 95
GPC (PS calibration)
Mw (g/mol) 10010 8320 4620
Mn (g/mol) 2910 2720 1770
U = Mw/~ 3.4 3.1 2.6
Hazen color numker
(Lovibond) 60 50 30
Appearance tra~rer,ttr3~rer,t tr3~r~t
2l28~
- 23 -
Initiators: -
: :-
A di-t-butyl peroxide: TrigonoxQ B (AKZ0)
B t-amyl peroxy-2-ethylhexanoate: Trigonox~ 121 (AKZ0)
C di-t-amyl peroxide: Interox~ DTAP (Peroxid-Chemie)
5 GPC: Mw, Mn Millipore~ Waters Chromatography System
860
Pump: Waters model 590, RI detector: Waters model 410
Column packing: Waters Ultrastyragel 1 x 1000 A + -
1 x 500 A + 1 x 100 A
(Angstrom)
Solvent: tetrahydrofuran at 40C
Flow rate: 1 ml/min, concentration: 1% based on solids
content
Calibration: polystyrene (PSS, Mainz)
Determination of characteristics: Acidn ~ er,hydroxyl~m~er
and viscosity (for standards see "Analytische
Bestimmungsmethoden" [Analytical determination methods~
(brochure: Synthetic resins Hoechst AG, 1982 edition)). Hazen
color number (Lovibond) according to DrN 53 409.
The copolymers Dl and D2 prepared have relatively low
- weight-average molar masses. The gel permeation
chromatograms show no high molar mass "shoulders", which
is evident in a relatively low nonuniformity.
In accordance with the lower molar masses and the
higher degree of uniformity, there is a reduction in the
supply form viscosity as measured in an Ubbelohde
viscosimeter. ~-
i. :
212~
- 24 -
II.) Preparation of the coating materials
To prepare the curable coating compositions according
to the invention, the components - comprising a copolymer
according to the invention or a mixture of two or more
copolymers according to the invention with the
auxiliaries and additives, solvents and crosslinking
agents in the mixing ratio described in Tables 5 and 6 -
are mixed and are adjusted using further diluent to the
spray viscosity of from 21 to 22 seconds with a flow cup
(DIN 52 211, 4 mm, 23C). Binder as supplied (supply
form, "SF") and additives are mixed to yield 100 parts by
weight in total. Curing agent (isocyanate) is added then.
For components of low viscosity this can be carried out
in bulk, with heating to higher temperatures being
carried out if desired. Products of higher viscosity are
dissolved or dispersed, prior to mixing, in the diluents
mentioned, unless the curable mixtures are to be employed
as a powder coating.
In the case of pigmented systems a pigment paste is
first produced in one dispersion step from the
appropriate pigments together with the copolymer
according to the invention, or a mixture of two or more
copolymers according to the invention, with the optional
addition of an appropriate, specific grinding resin in a
dispersion apparatus of appropriate construction. This
paste is mixed as it is, or with the addition of another
binder based on the components, or on a mixture thereof,
or alternatively with the addition of a different resin,
which is compatible with the other components of the
coating system concerned, and this mixture is made up
with the addition of further diluents or additives
typical for coatings.
The pot life and the properties of the resulting
films depend in this context on the process conditions,
in other words on the nature and quantity of the starting
materials, the metering of the catalyst, the temperature
control, etc.; curing can be carried out discontinuously
,, , . :
, 2l28~l
- :
or continuously, for example, using an automatic coating
apparatus.
2128~
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~u -~ ~ ~ ~
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~ ti ~l
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~Ul~ - ~1 14 N 0 ~ g ~ 3E I
~ 5~ -1 1 ~ ~: tq _~ ~ tn
U~l ~ ~1 .,~ ~ Ul ~ ~ U Ln ra ~ ~ I
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2128~
- 28 -
Tinuvin~ 292 "HALS" (Ciba Geigy, Basle)
Tinuvin~ 1130 W absorber (Ciba Geigy,
Basle)
Si oil L0 50~ Leveling agent (silicone oil
from Wacker GmbH,
Burghausen)
Desmodur~ N 3390 Polyisocyanate containing
isocyanurate groups (Bayer
AG, Leverkusen)
10 BuAc Butyl acetate
III.) Performance testing
The coating systems prepared as in II were applied
to clean
ed glass panels using a 100 ~m doctor blade and were
tested under the conditions of air drying and of forced
drying (45 minutes at 60C).
The results can be taken from Tables 7 and 8.
Coatings based on DTAP-initiated products are notable for
a solids content which is about 2-4% higher, a dust-dry
time which is just as good or even shorter, a reduced
tack-free drying time and comparable or improved film
hardness. The gasoline resistance corresponds to the
known, high level.
Testing is performed after drying at room temperature
for 24 hours, 2 days etc., or under forced conditions (45
minutes at 60 C in an oven) and subsequent storage.
Pendulum hardness is measured according to Konig.
Solids content is measured after drying at 125 C for
1 hour (DIN 53 216).
Gasoline resistance is tested by application of a
soaked cotton pad on to the coated surface. The time
during which the appearance does not change is stated in
the table.
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