Note: Descriptions are shown in the official language in which they were submitted.
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Polyfunctional epoxide compounds
l'he present invention relates to novel polyfunctional epox-
ide compounds obtainable by reacting
A) polyfunctional aromatic amines, in which the amino
groups carry more than two glycidyl groups per molecule,
with quantities of
B) b1) an alkylphenol in which the alkyl radicals contain
1 to 12 carbon atoms,
b2) a primary or secondary aliphatic amine in which the
alkyl radicals contain 1 to 10 carbon atoms, or
b3) an aliphatic C1-C20-alcohol
or mixtures of two or more of components (bl) to ~b3),
such that the reaction products carry on average two epoxide
groups per molecu]e.
The invention also relat2s to the production of the poly-
functional epoxide compounds. The invention also relates to
synthetic resins which can be prepared from the novel epox-
ide compounds, and to the preparation of these synthetic
resins and to their use for heat-curable coating composi-
tions. Finally the invention relates to electrodepositionbinder systems containing the abovementioned synthetic res-
ins, to dispersions prepared from these resins, to a process
for electrodeposition using these dispersions, and to ar-
ticles coated using this process.
Coatings on metallic components in the automobile industry,
which are applied by cathodic electrodeposition and are then
heat-cured, are subject to a number of requirements. For
instance, they should offer, inter alia, good protection
~0 against corrosion. They should in addition be sufficiently
elastic to prevent the impact of stones leading directly to
chipping of the coating.
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lrhe coatings proposed in DE-A-35 42 168 contain as binders a
polyaddition~polycondensation product carrying groups con-
taining basic nitrogen. Such a product is prepared by react-
ing an addition product built up Erom a secondary amine and
polyepoxide compounds with a specific polyamide. In coating,
this binder results in good protection against corrosion and
is sufficiently elastic at ambient temperature to give ef-
fectlve stone-chip protection. At lower temperatures, how-
ever, the embrittlement of the coating results in inade~uate
protection against stone-chipping.
It is therefore an object of the present invention to pro-
vide binders for electrodeposition coating which give good
protection against corrosion and which remain elastic at low
temperatures so as to be insensitive to stone-chipping.
We have found that this object is achieved by the polyEunc-
tional epoxide compounds defined above.
We have also found a process for their preparation, syn-
thetic resins containing these epoxide compounds, and a pro-
cess for preparing these synthetic resins. We have addition-
ally found binder systems which are suitable for electrode-
position coating and which contain these synthetic resins,
dispersions prepared from these binder systems, a process
for electrodeposition coating using these dispersions, and
articles coated by this process.
The following text describes particularly advantageous em-
bodiments for the application of the polyfunctional epoxide
compounds in electrodeposition coating.
Component A
The compounds suitable as component (A) are derived from
polyfunctional aromatic amines which generally carry 2 amino
groups per molecule. Suitable compounds for this purpose are
therefore 9,10-diaminoanthracene,
2,2-bis-(4-aminophenyl)propane,
~0 4,4'-diaminobenzophenone,
1,2-bis-(4-aminophenyl)ethane,
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bis-(2 aminonaphthyl~methane and
1,5-diaminonaphthalene, and
preferably 4,4'-diaminodiphenylmethane.
These polyfunctional aromatic compounds are reacted with an
epihalohydrin by a known method (cE. eg. EP-A-0 lS5 238~ to
give products carrying more than 2, preferably 3 to 4 and
paLticularly preferably on average 3.5 to 4 glycidyl groups
per rrlolecule. 5Ome of these products are also commercially
available.
Component B
Component (A) is reacted with compounds which are reactive
toward epoxide groups. Suitable examples are:
bl) Alkylphenols, in which the alkyl radicals contain 1 to
12 carbon atoms.
PreEerence is given to monoalkylphenols containing 4 to
12 carbon atoms in the alkyl radical. 4-Nonylphenol and
4-dodecylphenol are particularly preferred.
b~) Primary or secondary aliphatic amines in which the alkyl
radicals contain 1 to 10 carbon atoms.
It is preferred to use secondary amines. The alkyl radi-
cals preferably contain 3 to 6 carbons. Diiso-propyla-
mine, di-n-propylamine, di-n-butylamine, dipentylamine
and dihexylamine are particularly preferred.
b3) Aliphatic Cl-C20-alcohols.
Methanol, ethanol, iso-propanol, n-propanol, iso-butanol
and n-butanol are preferred.
It is also possible to employ mixtures of components (bl) to
(b-,) as component (B).
Components (A) and (B) are mixed and expediently heated to
from 100 to 160"C. It is often advantageous here to carry
out the reaction in a polar solvent such as ethylene gIycol
monobutyl ether or propylene glycol monophenyl ether, the
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solvent generally making up from 5 to 30% by weight of the
mixture. In the presence of component (B) there is only a
minor degree of reaction between component (A) and one of
the hydroxyl-containing solvents mentioned.
The reactio~ of (A) and (B) is advantageously carried out in
the presence of a catalyst, such as a tertiary amine and
preferably an aliphatic tertiary amine, such as tributyla-
mine or diethylhe~ylamine. Depending on the number oE
glycidyl groups in (A), the quantities of (B) are chosen
such that the reaction product carries on average two epox-
ide groups per molecule.
Component C
~5
The polyfunctional epoxide compounds prepared from compo-
nents (A) and (B) can be reacted to give synthetic resins.
This is effected by reaction with component (C), which com-
prises the following individual compounds:
cl) Polyalkylene oxides having an average molecular weight
from 200 to 2000.
These are preferably polymers of ethylene oxide,
1,2-propylene oxide, 1,3-propylene oxide or tetrahydro-
furan. Both homopolymers and copolymers of these
compounds can be used. Polytetrahydrofuran having an av-
erage molecular weight from 300 to 1000 is particularly
preferred.
C!) Polyalkylene oxides having terminal amino groups and an
average molecular weight from 200 to 2000.
These compounds are also derived from cyclic ethers such
as ethylene oxide, 1,2-propylene oxide, 1,2-butylene ox-
ide and tetrahydrofuran, the terminal groups being con-
verted to amino groups after polymerization by a known
method. Poly(tetrahydrofuran)diamines having an average
molecular weight from 250 bis 750 are particularly pre-
ferred.
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C3 ) Aliphatic amino-alcohols having a total of 2 to 12 car-
bons.
Suitable compounds are those containing primary and sec-
ondary amino groups, such as ethanolamine or methyletha-
nolamine, but it is also possible to employ compounds
with tertiary amino groups, such as dimethylamino-
propanol or triethanolamine.
c~) Bisphenols.
Suitable bisphenols are compounds such as
4,4'-dihydroxybenzophenone,
4,4'-dihydroxyphenyl sulfone,
1,1-bis(4--hydroxyphenyl)ethane,
1,1-bis(4-hydroxyphenyl)isobutane,
2,2-bis(4-hydroxy-3-tert-butylphenyl)propane,
Bis(4-hydroxynaphthyl)methane,
1,5-dihydroxynaphthalene or
preferably 2,2-bis(4-hydroxyphenyl)propane ( Bi sphenol
A).
It is also possible to use mixtures of components (c1) to
(C4 ) . A further possibility is to react various components
(C) in succession with polyfunctional epoxide compounds com-
prising (A) and (B). The function of component (C) is to
link the polyfunctional epoxide compounds to form a syn-
thetic resin.
The epoxides prepared from components (A) and (B) can be
reacted directly to give the synthetic resins. For this pur-
pose it is usual first to neutralize the amine catalyst -
when present - with an acid. Component (C) is then added, a
catalyst such as triphenylphosphine may be added, as is the
case when using bisphenols, and the mixture is heated to
about 100 to 160C, until all the epoxide groups have
reacted. It has proven advantageous to carry out this
reaction in a solvent, since the mixture becomes more vis-
cous during the reaction. Suitable solvents in this case are
ethylene glycol monobutyl ether or propylene glycol mono-
phenyl ether.
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The resulting synthetic resins form a constituent of binder
systems which can be used for electrodeposition coating.
These binder systems contain from 50 to 95% by weight, pre-
ferably 50 to 75~ by weight, of the synthetic resins. They
also comprise a crosslinking agent D in amounts from 5 to
50, and preferably 25 to 50~ by weight.
Crosslinking agent D
~0 The crosslinking agents D, which are known per se, are
compounds which are able to efEect crosslinking by various
types of reaction. The following classes of compound are
preferred in this context:
dl) amidation crosslinkers,
d2) transamination crosslinkers,
d3) transesterification crosslinkers and
d4) blocked polyisocyanates.
dl) Amidation crosslinkers are those organic compounds which
react with primary and/or secondary amino groups in the
synthetic resin to form amide lin]cs, this reaction only
taking place under stoving conditions. Examples of these
are resins containing at least two carboalkoxymethyl
groups and having an average molecular weight from 200
to 10,000, whose structure is described in DE-A-31 45
714.
d~`) Transamination crosslinkers are organic compounds which
likewise react with primary and/or secondary amino
groups in the synthetic resin under stoving conditions,
with elimination of amine, so that crosslinking agent
and synthetic resin are linked by these groups. Examples
are Mannich bases which are built up from phenols, form-
aldehyde and secondary amines. Particular preference is
given to those compounds which are built up from polyal-
kylene oxide diglycidyl ethers with phenols such as bis-
phenol A, and are then reacted with dialkylamines such
as dimethylamine, diethylamine, or piperidine and with-
formaldehyde or formaldehyde-donor compounds.
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d-~ Transesterification crosslinkers can undergo transes-
terification reactions with synthetic resins containing
hydroxyl groups. Examples are resins comprising acrylic
acid esters, or resins containing malonic ester groups,
S which are described in DE-A-37 35 601.
d,1) Polyisocyanates are particularly preferred. Examples of
these compounds are tolylene diisocyanate,
4,~'-diphenylmethane diisocyanate, isophorone diiso-
cyanate and trimerized hexamethylene diisocyanate. These
isocyanates are preferably employed in blocked form.
Customary blocking agents are amines such as dibutyla-
mine, which react to give urea compounds, alcohols such
as methanol, ethanol or polyhydric alcohols such as
polyoxyalkylene glycols, which form urethane groups, and
ketoximes such as methyl ethyl ketoxime, which likewise
react bY addition to an isocyanate group.
The binders according to the invention are dispersible in
water after partial or complete neutrali2ation. Acids suit-
able for the neutralization are preferably carboxylic acids
such as formic acid, acetic acid, propionic acid or lactic
acid, but also include inorganic acids such as phosphoric
acid. The neutrali~ation of the synthetic resin and the
crosslinking agent can be carried out separately, but is
preferably carried out in unison after prior mixing. The re-
sulting dispersions can be diluted with water, possibly af-
ter removing organic solvent, to a desired solids content.
For preparing electrodeposition baths the binders accordlng
to the invention can be admixed with further binders, pig-
ments and auxiliaries and additives conventional in electro-
deposition coating, such as fillers, corrosion inhibitors,
dispersion auxiliaries, antifoams and/or solvents.
Electrodeposition coating is carried out by a conventional
procedure.
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The binders according to the invention afford, after ca-
thodic deposition and heat-curing, a good protection against
corrosion on metallic components. They also have - even at
]ow temperatures - only a slight sensitivity toward stone-
chipping.
The po:Lyfunctional epoxide compounds according to the inven-
tion are of interest as components of epoxy resins. Novel
binders prepared therefrom find application as heat-curable
coatings.
Examples
1.1 Preparation of a polyfunctional epoxide compound ac-
cording to the invention
3.08 kg of a polyglycidyl ether based on
4,4'-diaminodiphenylmethane (epoxide equivalent
weight 7'7; average number of epoxide groups per mole-
cule 3.8) in 760 g of ethylene glycol monobutyl ether
were mixed with 1100 g (5 mol) of 4-nonylphenol and
3.35 g of diethylhexylamine and heated at 130C until
the epoxide equivalent weight was 385.
1.2 Preparation of a synthetic resin ~ according to the
invention
After addition of 6.35 g of concentrated formic acid
to the reaction mixture obtained in 1.1, 513 g (2.25
mol) of bisphenol A and 1.10 g of triphenyl phosphine
in 110 g of ethylene glycol monobutyl ether were
added. The temperature was maintained at 130C until
the epoxide equivalent weight was 650. At 70C 300 g
of polytetrahydrofurandiamine having an average mo-
lecular weight of 600 and 165 g (1.58 mol) of
dimethylaminopropanol were added. The mixture was
maintained at this temperature until no further epox-
ide groups could be detected.
The resin solution at a solids content of 85~ by
weight had a viscosity of 4400 mPas at 75C.
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1.3 Preparation of a com~arative synthetic resin Rc (ac-
cording to DE-A-35 42 168)
3.06 kg (3.15 mol) of a diglycidyl ether based on
S bisphenol A and eplchlorohydrin (epoxide eq~livalent
weight 485) in 570 g of toluene and 534 g of iso-
butanol are mixed at 65"C with 135 g (1.8 mol) of me-
thylethanolamine. When the mixture had reached an
epoxide equivalent weight of 835, 656 g of a solution
of a condensation product and 140 g of toluene were
added, and the mixture was heated for 2 h at 80C.
The condensation product was prepared by reacting 290
g (2.5 mol) of hexamethylenediamine, 218 g (0.39 mol)
of dimerized fatty acid and 70 g (0.25 mol) of
linseed oil fatty acid at 195C, distilling off the
water oE reaction. After addition of 242 g of toluene
this solution had a solids content of 70% by weight
and an amine nurnber of 350 mg/g.
2. Preparation of crosslinking agents
2.1 Crosslinking agent D1 (according to Example 1 of
EP-A-304 834)
425 g of polyoxypropylene glycol having an average
molecular weight of 425 at 60C were added to 696 g (4
mol) of toluylene diisocyanate`(80% by weight of the
2,4- and 20 ~ by weight of the 2,6-isomer) and 2.8 g
of dibutyltin dilaurate as catalyst. 522 g (6 mol) of
methyl ethyl ketoximP were then added to the mixture
which was maintained at 60C until no further free
isocyanate groùps could be detected.
2.2 Crosslinking agent D2
5.04 kg (10 rnol) of trimerized hexamethylene diiso-
cyanate in 3.80 kg of methyl isobutyl ketone were
reacted at 70C with 3.88 kg (30 mol) of dibutylamine
until no further free isocyanate groups could be de-
tected.
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3. Preparation of dispersions
3.1 Preparation of dispersions of R
3.1.1 Example 1
780 g of R were mixed with 340 g of Dl and neutral-
ized with 19.5 g of acetic acid. The organic solvents
were removed by azeotropic distillation and the dis-
persion was adjusted to a solids content of 35% by
weight with water.
3.1.2 Example 2
Procedure as for 3.1.1; 780 g of R, 485 g of D2
3.2 Preparation of a dispersion of Rc (Comparative exam-
ple)
~0 Procedure as for 3.1; 695 g of Rc; 298 g of D2; neu-
tralization with 16 g of acetic acid
4. Preparation of a pigment paste
580 g of diglycidyl ether based on bisphenol and
epichlorohydrin (epoxide equivalent weight 485) and
145 g of a similar diglycidyl ether having an epoxide
equivalent weight of 188 were added at 100C to 452 g
(3.9 mol) of hexamethylenediamine. After 30 minutes
the excess diamine was stripped off at 200C and 30
mbar. Then 57.6 g (0.2 mol) of stearic acid and 173 g
(0.3 mol) of dimeric fatty acid in 115 g of xylene
were added. The water of reaction which formed was
removed by azeotropic distillation at 175C. After
addition of 58 g of ethylene glycol monobutyl ether
and 322 g of isobutanol the reaction solution had a
solids content of 7Q% by weight and a viscosity of
2240 mPas at 75 C. 110 g of this resin solution were
milled in a ball mill with 36 g of ethylene glycol
monobutyl ether, 3 g of acetic acid, 170 g of tita-
nlum diox~:e, ~ g of lead sili~aee, 4.5 g ^f carbon
.
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black and 170 g oE water to a particle size of below
7 ~Im.
5. Electrodeposition coating and measurement data
19~2 g of dispersion and 69~ g of pigmerlt paste were
mixed and adjusted to a solids content of 20% by
weight with water.
At ambient temperature, coatings were applied by de-
position at 250 to 500 V in conventional manner to
phosphatized metal panels connected as cathode, and
the coatings were cured for 20 minutes at a panel
temperature of 165C.
Stone chip test ~in accordance with DIN 55 995, Method A)
At -20C a coated metal sample panel was struck with 5 blows
of a hammer at different points. The parameters measured
were:
1. The area of coating chipped off, in mm2
2. The number of blows which exposed the panel.
This nu~ber is an indirect measurement of how deeply the
coating is damaged by stone-chipping, and how often cor-
rosion sites can form on a panel attacked in this way.
Chipping [mm~] Number of blows
_____ which exp sed the
Example 1 6 2
(as in 3.1.1)
35 Example 2 5 1
(as in 3.1.2) _ _ _
Comparative exam- 10 5
(as in 3.2) _ _
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We claim:
l. A polyfunctional epoxide compound which can be obtained
by reacting
A) a polyfunctional aromatic amine, in which the amino
~roups carry more than two glycidyl groups per mol-
ecule, with ~1antities of
B) b1) an alkylphenol in which the alkyl radicals con-
tain 1 to 12 carbon atoms,
b2) a primary or secondary aliphatic amine in which
the alkyl radicals contain 1 to 10 carbon
atoms, or
b3) an aliphatic Cl-C20-alcohol
or a mixture of two or more of components (b1) to
(b3),
such that the reaction product carries on average two
epoxide groups per molecule~
2. A polyfunctional epoxide compound as claimed in claim 1,
in which component (A) is N,N,N',N'-tetra-
glycidyl-4,4'-diaminodiphenylmethane.
3. A process for the preparation of a polyfunctional epox-
ide cornpound as claimed in claim l, which cornprises
reacting
A) a polyfunctional aromatic amine, in which the amino
groups carry more than two glycidyl groups per mol-
ecule, with c~uantities of
B) b1) an alkylphenol in which the alkyl radicals con-
tain 1 to 12 carbon atoms,
