Note: Descriptions are shown in the official language in which they were submitted.
2404~US3420 2 ~ 2 2 ~J'~ ~ ~
PROCESS FOR THE PREPARATION OF
SELF-CROSSLINKING CATIONIC PAINT BINDERS
_ELATED PATENTS
This application relates to the subject matter
of commonly assigned U.S. Patent Nos. 4,711,934; 4,711,935;
4,845,170, and 4,845,171.
FIELD OF INVENTION
The present invention relates to a process for the
preparation of self-crosslinking, cationic paint binders
which can be diluted with water after protonation and to the
binders obtained. More particularly, the binders are based
on reaction products formed from aminoalkylation products of
phenols with epoxy resins wherein the diepoxy resins employ-
ed in the final processing stage are modi~ied proportionally
with monoamines and diamines.
BACKGROUND OF INVENTION
Processes for the preparation of reaction products
formed from aminoalkylation products of phenols with epoxy
resins are described in U.S. Patent Nos. 4,711,934;
4,711,935; 4,845,170 and 4,845,171, corresponding substan-
tially to Austrian Patent Nos. 382,160; 384~232; 384,818;
385,048; 386,220; 386,221, and 390,071. Austrian Patent
No. 382,160 and U.S. Patent Nos. 4,711,934 and 4,845,170
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2404/US3420
disclose a process for the preparation of self-crosslink-
ing, cationic paint binders which can be diluted with water
after protonation based on reaction products formed from
aminoalkylation products of phenols with epoxy resins, char-
acterized in that -
(1) an aminoalkylation product which contains on averageat 12ast one NH group per molecule and has been formed
from phenol and/or a substituted phenol, preferably a
monoalkylphenol or monoarylphenol or monoaralkylphenol
having one or, if appropriate, two phenolic hydroxyl
groups, a primary alkylamine and/or primary alkanol-
amine and/or primary/tertiary alkyldiamine and formal-
dehyde or a formaldehyde donor, is reacted with
(2) a half-masked diisocyanate and, in a further reaction
stage,
(3) 50 to 100% of the phenolic hydroxyl groups of the
product of (1) and (2) are reacted with epoxy com-
pounds, preferably diepoxy resins having an epoxide
equivalent weight between 50 and 2000.
According to the present invention, it has now
been found that the application and rheological properties
of the coating agents based on tha products of the aforesaid
patents can be improved if the diepoxy resins employed in
the final processing stage are modified by a partial reac-
tion with monoamines or diamines.
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2404/US3420 2 ~ 2 2 ~ ~ ~
SUMMARY OF INVENTlON AND GENERAL DESCRIPTION
Accordingly, the present invention relates to a
process for the preparation of self-crosslinking, cationic
paint binders which can be diluted with water after protona-
tion and are based on reaction products formed from amino-
alkylation products of phenols and epoxy resins, which have
been obtained by reacting
(l) an aminoalkylation product which contains on average
at least one NH group per molecule and has been formed
from phenol and/or a substituted phenol, preferably a
monoalkylphenol or monoarylphenol or monoaralkylphenol
having one or, if appropriate, two phenolic hydroxyl
groupsj a primary alkylamine and~or primary alkanol-
amine and/or primary/tertiary alkyldiamine and formal-
dehyde or a formaldehyde donor, with
(2) a half-masked diisocyanate, and subsequently reacting
(3) 50 to 100% of the phenolic hydroxyl groups of the
product of (1) and (2) with epoxy compounds, preferably
diepoxy resins having an epoxide equivalent weight
between 50 and 2000,
which is characterized in that 5 to 70 mole ~, preferably
10 to 40 mole %, of the glycidyl groups of the epoxy com-
pounds employed in stage (3) are reacted with monoamines
and/or diamines before they are reacted with the inter-
mediate product obtained in stage (2) or, if appropriate,
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2404/US3420 2~2~ ~ ~
at the same time as they are reacted in accordance with
stage (3). The invention also embraces the modified cross-
linking cationic paint binders obtained by practicing the
process. The modification of the binders according to the
present invention provides further means for influencing the
application and rheological properties of the binders, the
paints formulated therewith, and the deposited films when
the latter are crosslinked.
The preparation of the precursors and intermediate
products employed is carried out in accordance with the man-
ner descrihed in U.S. Patent Nos. 4,711,934 and 4,845,170.
Monoamines which can be employed for reaction with the epoxy
component according to the present invention are essentially
all primary and secondary amines, such as the homologous
monoalkyl monoamines or dialkyl monoamines or the homologous
monoalkanol monoamines or dialkanol monoamines. The di-
amines employed are preferably reaction products of dipri-
mary amines with 2 mole of monoepoxy compound. Primary-
tertiary diamines, such as dimethylaminopropylamine and
homologues, are also preferred.
In a particular embodiment, the amine-functional
compounds employed according to this inven-tion are the oxa-
zolidine amines described in U.S. Patent No~ 4,431,781, cor-
responding to European Patent No. 0,076,955, which have the
genaral formulae -
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2404/US3420
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R3 ~ ÇH ~ CH ~ NH - R1 ~ N--- CH - R4
OH l l
R2~ \
and/or
II)
R4 ~ CH N ~ ( CHz ) n NH ~ X
o~ ~ R
and/or
(III)
R5 - NH ~ R1 ~ N I H - R"
R2
R ~ ~O ~ 6
wherein -
R1 denotes a linear or branched or cyclic alkylene radical
having 2 to 12 carbon atoms or an aralkylene radical,
R2 denotes a linear or branched alkyl radical having l to
4 carbon atoms, an aryl radical or an H atom or, for
both R2 groups jointly, a ring-forming alkylene radical
which is optionally substituted by alkyl, aryl, or
alkoxy radicals,
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2404/US3420
R3 denotes a saturated or unsaturated, aliphatic or cyclo-
aliphatic or aromatic hydrocarbon radical which option-
ally contains ether or ester groupings,
R4 denotes H or CH3-,
R5 denotes a radical remaining after reaction with an
active hydrogen atom of an acrylic or methacrylic
monomer which is monofunctional in respect of the
double bonds of the monomer,
R6 denotes a hydrogen atom or an alkyl radical,
n denotes a numerical 2, 3 or 4, and
X denotes either -
( CH2 ) n ~ N CH - R4
R2
R "' ~0 ~ 3
or ;
R14
(CH2) n ~ NH - CH ~ fH - R3
OH
The reaction of the diepoxy or polyepoxy compounds
with the amines is carried out either before or at the same
time as the reaction of the epoxy compounds with the phenol
component. In either case, the reaction is carried out at
60C - 100C, and the ratios and the reaction conditions
ars chosen in order that the end products do not contain
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2404/US3420 2~22~ ~
free epoxy groups. There is no essential di~ference between
the end products prepared by the two process variants.
In order to achieve dilutability with water, the
basic groups of the reaction product are neutralized par-
tially or completely with acids, preferably with formic
acid, acetic acid, or lactic acid. Usually neutralization
of 20 - 60% of the basic groups or an amount of approxi-
mately 20 t.o 60 millimole of acid per 100 g of solid resin
is sufficient for a dilutability which is suitable or prac-
tical use. The bindexs are then diluted with deionized
water to the desired concentration. If desired, they are
processed with crosslinking catalysts, pigments, filler,
and other additives to give pigmented paints before neutra-
lization or before dilution, or in a partly diluted state.
- The formulation of such paints and their appli-
cation in the electrocoating process are known to those
skilled in the art and are described in the literature. The
curing of the deposited coatings is carried out, when used
as primer, at temperatures between 150C and 170C for 10 to
30 minutes. If the binders do not contain self-crosslinking
structures in an adequate amount, concomitantly additional
crosslinking agents can be used, such as masked isocyanates
or amino resins or phenolic resins. If suitably formulated,
the products can also be applied by other processes, such as
dipping, rolling, or spraying. If desired, the binders can
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2404/US3420 C~ 2 ~
also be processed in organic solvents.
ILLUSTRATIVE EXAMPLES AND PREFERRED EMBODIMENTS
The following examples illustrate the invention
without limiting its scope. Unless otherwise specified, all
data in parts or percentages relate to units of weight.
The following abbreviations are used in the e~am-
ples:
PH........ phenol
NPH....... nonylphenol
BPA....... bisphenol A
DMAPA... N,N-dimethylaminopropylamine
DEAPA... N,N-diethylaminopropylamine
EHA....... 2-ethylhexylamine
EGL....... monoethylglycol monoethylether
MIC I... toluylene diisocyanate, half-masked
with EGL
MIC II.. toluylene diisocyanate, half-masked
with 2-ethylhexanol
EPH I... diepoxy resin based on bisphenol A and
epichlorohydrin (epoxide equivalent weight
approximately 190)
EPH II.~. diepoxy resin based on bisphenol A and
epichlorohydrin tepoxide e~uivalent weight
approximately 480)
EPH III.. glycidyl ether of tertiary C9/C11-mono-
carboxylic acids (epoxide equivalent weight
250)
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2404/US3420
OXAM I.. oxazolidine amine formed from 1 mole of
aminoethylethanolamine, 1 mole of 2-ethyl
hexyl acrylate, and l mole of formaldehyde
(MW = 300)
OXAM II. oxazolidine amine formed from 1 mole of di-
ethylenetriamine, 2 mole of octene oxide, and
2 mole of formaldehyde ~MW = 231)
DIAM...... reaction product of 1 mole of pentamethylene-
diamine with 2 mole of EPH III (MW = 602)
DOLA...... diethanolamine
DGDM...... diethyleneglycol dimethylether
MOP....... methoxypropanol
The preparation of the modified aminoalkylation
products (VP 1 to 4~ is effected in accordance with the
examples in U.S. Patent No. 4,711,934, in the ratios indi-
cated in Table 1 as follows:
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Preparation of the Binders
Accordin~ to the Invention
Examples 1 - 6
The reaction of the starting materials indicated
in Table 2 can be carried out either in a one-stage process
or in a two-stage process. There is no difference in the
properties of the products prepared by the two processes
which go beyond customary variations.
In the one-stage process, the components are
reacted in a 70% strength solution in the solvent indicated
in Table 2 at 95C to 100C until the epoxy groups have been
completely reacted. Monoglycidyl compounds which can be
employed are in this case preferably not reacted until after
the reaction of the diepoxy resins with the amine compounds.
In the two-stage process, the diepoxy resin is
reacted in the first stage at 60C to 80C with the amine
compound until the amount of epoxy groups corresponding
stoichiometrically to the aminohydrogens has reacted. After
the modified aminoalkylation product (VP) and the monogly-
cidyl compound, if employed, have been added and after the
solids content has been adjusted with solvent to 70 to 75%,
further reaction is carried out at 90C to 100C until an
epoxide value of virtually zero i5 reached.
For further processing, the products are adjusted
to th~ solids content indicated in Table 2. The solvents
used are the glycol ethers, preferably methoxypropanol.-
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2404/US3420
The column "Solubility" in Table 2 indicates theamount of formic acid (in millimole) per lO0 g of solid
resin, which is required in order to give a stable clear
lacquer after dilution with water to a solids content of
15~.
Table 2 is as follows:
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r~ c~ l` ~ ~ ~ ~r
r~ ~ ~ U~ o o
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The binders prepared in accordance with Examples
1 to 6 were deposited by electrical means in the form o a
clear lacquer onto steel sheets. The clear lacquer was pre-
pared by adding an amount of dibutyltindilaurate correspond-
ing to 0.8% of metal (relative to solid resin) to the resin
solution obtained in accordance with the example, and the
mixture was diluted to a solids content of 15~ with deion-
ized water. The films were stoved for 20 minutes at 160C,
and, at a film thickness o~ 20 + 2 ~m, had a resistance to
methylethylketone of at least 150 double rubs.
As will be apparent to one skilled in the art,
various modifications can be made within the scope of the
aforesaid description. Such modifications being within the
ability of one skilled in the art form a part of the present
invention and are embraced by the appended claims.
14
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