Note: Descriptions are shown in the official language in which they were submitted.
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o.Z. 0062/02097
Polymeric reaction products
The pre~ent invent~on relates to polymeric
reaction products which are obtainable from
A. a polyoxyalkylene which ha~ an average molecular
weight ~ of ~rom 140 to 10,000 and conta~n~ on
average from 1.5 to 3.0 primary and/or ~econdary
amino group~ and
B. a polym~r which i~ ba~ed on a con~ugated diena, has
an average molecular weight ~ of from 250 to 50,000,
contains on average from 1.5 to 3.0 epoxy group~ per
mole~ule and i8 obtainable by reacting a hydroxyl-
or carboxyl-containing polymer with a glycidyi
compound,
the amount of (A) being ~uch that from 1.3 to 3.0 amino
group~ of component (A) are present per epoxy group of
component (B).
The present invention furthor relates to aqueous
di~per~ions which contain ~uch poly~eric reaction pro-
duc~3 and to the U8Q of such disp2rsions as additio~ to
standard alectrocoa~ing ba~hs.
Automaker~ have in recent yeaxs become m~re vocal
in demanding cathodically depositable baYecoats for
multi-coat autopaint 8y8tem8 which confer on ~hese pain~
~ystem~ not only good corrosion ra3is~ance bu~ al80 a
high ~tone chip re3$stance. There are e~sentially two
rea~ons why they demand better ~tone chip resistance:
- the switch away from salt to gri~ or gri~/~alt
mixtures for use on the roads in winter; and
- thQ aerodynamically dic~a~ed evex low~r ~lat front
end~ of automob~ le8 .
EP-B-~550 describe8 aguesus cathodic coating
dispersions in which s~nthetic resins which ara obtain-
abl~ by rascting polyepoxie~ ba~sd on bi~phe~ol A with
polyoxyalkylenepolyamine~ are used ~ binders.
German Patent ~pplication P 3906145.0 di closes
two-pha~e cathodic electrocoating~ obtai~ed by depo~itlng
a mixtuxe of two di3per~ions whosa re~pective binders are
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incompa~ible with each other.
However, exi~ting systems fall short of meeting
expectation~ of excellent stone chip resistance coupled
with good corrosion protection and high levels of all the
other application properties.
It i~ an object of the present invention to
develop ~y~tams which have excellent propertieY not only
in respect of stone chip resistance but also in respect
of corrosion re~istance.
We have found that this ob~ect i~ achieved by the
polymeric reaction products def ined at the beginning.
Suitable components (A) are polyoxyalkylene
derivative~ which on average contain from 1.5 to 3.0,
preferably from 1.8 to 2.2, primary and/or secondary
amino groups and have an average molecular weight ~ of
from 140 to 10,000, preferably from 300 to 60ao, parti-
cularly preferably from 350 to 1100.
~ he preparation of such amino-containing polyoxy-
alkylQne~ i~ common knowled~e. They can be prepared for
example by Mi~hael addition of acrylonitrile to hydro~yl-
terminated polyoxyalkylene~ with sub~equent hydrogenation
of the nitril~ group, or by direct reaction of the OH-
functionalized compounds with excess ammonia.
Suitable polyoxyalkylenas are tho~e compounds
who~e alkylene moiety contain~ from 1 to 12 carbon atom~,
for example polyethylene oxide, polypropylene oxide or
preferabiy polytetrahydrofuran.
Particularly preferred amino-containing polyoxy-
allylane~ are those which have an un~ubstituted methylene
3Q group, in the ~-po~ition relative to a primary amino
group, ~uch as bis(2-a{ninoethyl)polyethylene oxide~
bis(3-aminoprvpyl) polyethylene oxids, bi~ ( 2-aminoethyl ) -
polypropylene oxide, bi~(3 -aminopropyl ~ polypropylene
oxide or preferably bi~(2-aminoathyl)poly~etrahydrofuran
or bi~(3aminopropyl)polytetrshydrofuran.
Suitable ~omponent~ (B) are polymers which are
ba~ed on con~ugated dienes, have a molecular weight ~ of
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- 3 - O.Z. 0062/02097
from 2~0 to 50,000, contain on average from 1.5 to 3.0
epoxy groups per molecule and are obtainable by reacting
hydroxyl- or carboxyl-carrying polymers with glycidyl
compound~.
The conjugated diene polymers can be obtained by
free radical polymerization under commonly known condi-
tions. Suitable diene monomer~ are for example isoprene
and butadiene, of which butadiene i5 preferred.
There may also be included monoolefinically
unsaturated monomer3 ~uch as styrene, acrylic acid,
acrylic ester~ with mono- or dialcohol~, acrylonitrile or
i~obutylene as comonomer~, of which acrylonitrile is
pxeferred.
The proportion of comonomer in a copolymerization
may in general, depending on the natura of the comonomer,
be up to 45 % by weight, based on the ~otal wei~ht of
monomers, the propor~ion of comon~mer being determined in
such a way that the glass tran~ition temperature of the
re~ulting copolymer comes to lie wit~in the range from
-70 to -30C, which, as will be known, iY an easy matter
for the skilled worker.
Preference i8 given to butadiene/acrylonitrile
copolymers ha~ing an acrylonitrile content of from 5 to
45 % by weight, particularly preferably from 10 to 30 %
by weight.
Suitable polymers which are based on butadiene
will have been functionalize~ with carboxyl or hydroxyl
groups .
The functionalization i~ effsc~ed in a conven-
tional manner, ~or example by using a carboxyl-containing
free radical initiator such as carboxylated azobisiso-
butyronitrile in the polymerization.
Functionalization with hydroxyl may be effected
for example by reacting a carboxyl-functionalized polymer
with ethylene oxide.
By reac~ion with glycidyl compounds which are
capable of rea~ting with the ~unctional groups it is
.
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_ 4 o.z. 0062/02097
pos~ible to introduce epoxy-containing group~ into the
polymer molecule~.
For instance, the hydro~yl-functionalized poly-
mer~ can be epoxy-modified by reaction with epihalohydrin
in an alkaline medium.
Carboxyl-functionalized polymers can be converted
into the corresponding epoxy-modified compound~ by
reaction with polyglycidyl ethers which contain from 1.5
to 3.0 epoxy groups on a~erage, of which di~lycidyl
- 10 ethers are preferred.
Suitable polyglycidyl ethers are fox example the
diglycidyl ethers of aliphatic C2-C1~-diols such as
ethylene glycol, propylene glycol, butanediol, pentane-
diol or hexanediol or polyglycidyl ether~ of monocyclic
or polycyclic aroma~ic compounds which contain two or
more phenolic hydroxyl group~ such as hydroquinone, 2,2-
bis(4-hydroxyphenyl)propane tbi~phenol A), bi~(4-hydroxy-
phenyl)methane (bisphenol F), 4,4'-dihydroxybenzophenone,
4,4~-dihydroxyhenzosulfone or 1,5-dihydroxynaphthalene.
Such glycidyl ethers can likewise be pxepared in
a conventional manner by etherification with epihalo-
hydrin in alkaline medium.
The r~action of the amino-containing polyoxy-
alkylene components (A) with the epoxy-modified polymer~
(B) i3 in general carried out in an organic ~olvent or
solvent mixture which is inert not only toward amino
group~ but also toward epoxy groups at 20-150C, prefer-
ably 50-110C. Suitable solvents are toluene, xylene,
benzene, m~t~yl isobutyl ketone and tetrahydrofuran, of
which toluene i~ preferred~
The reaction time may vary within $hs range from
1 to 16 hour~, the end point of the reaction having been
reached when the epoxy value i8 virtually equal to zero,
which is ea~y to determine in any particular case.
Normally, tha reaction i3 carried out under
atmospheric pressure.
The amounts of components (A3 and tB) are
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determined in ~uch a way that from 1.3 to 3.0, preferably
from 1.7 to 2.3, amino equivalent~ of component (A) are
present per epoxy equivalent of component (B).
The polymeric reaction products thus obtained
generally have amino number~ of from 10 to 100 mg,
preferably from 20 to 60 mg, of ROH/g of solid substance.
The average molecular weight ~ may ranga from 500
to 150,000.
After the epoxide-amine reaction, the amino
groups may be wholly or partly neutralized with acid an~
the protonated re~in be dispersed in water. A sui~able
acid i9 phosphoric acidr but preference is given to
organic acids, for example formic acid, acetLc acid,
propionic acid and lactic acid. It i~ also possible to
add the resin to a water/acid mixture and to disper~e it
therein by stirring. Thereafter the organic sol~entY can
be di~tilled off azeotropically.
~ he dispersions thus obtained have a solids
content of from 15 to 40 ~ and can be added to standard
electrocoating bath~.
For thi~ dispersion~ are used in amou~t~ of from
5 to 30 % by weight, preferably from 8 to 20 % by weight,
based on the polymer content of the electrocoating bath.
Suitable standard electrocoating bath~ generally
contain polymers with pendant primary, secondary or
tertiary amino groups as the principal r~in component.
It is aiso possible to use resins which have pendant
phosphonium or ~ulfonium groups. Generally, these resins
additionally contain functional groups, for example
hydroxyl group~ or unsaturated double bond~.
Suitable resins of ~his type, the molecular
weight of which is pref~rably within the range from 2000
to 200,000, are chain growth polymers, eg. aminoacrylate
and aminomethacrylate resin~, polyadduct~ such a~ amino-
polyure~hane resin~ and polycondensate~ such a~ amino-
apoxy re~ins.
The resins for basecoat primers intended to
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confer yood corrosion prot~ction propertie~ are prefer-
ably amino-epoxy resins. Amino-epoxy re ins are described
for example in EP-A-134 983, EP-A-165 556, EP-A-167 029,
DE-A-34 22 457 and D~-A-34 44 410.
They are obtained in a conventional manner by
reacting epoxide containing resins with saturated and~or
un~aturated primary and/or secondary amines or amino
alcohols. Suitable epoxy re$in~ are compounds which on
average have from 1.5 to 3, preferably 2, epoxy groups
per molecule and a~erage molecular weights of from 300 to
6000. Of particular suitability are glycidyl ethers of
polyphenols which on average contain 2 hydroxyl groups
per molecule, the preferred phenol component being 2,2-
bis(4-hydroxyphenyl)propane (bisphenol A).
Epoxy resins of higher molecular weight are
ohtained by reacting the abovementioned diglycidyl ethers
with a polyphenol such as 2,2-bi~(4-hydroxyphenyl)propane
and then with apichlorohydrin to give polyglycidyl
ethsrs.
The amino-epoxy resins may also have been modi-
fied with saturated or unsaturated polycarboxylic acids,
for example with adipic acid, fumaric acid or dimeric
fatty acid.
The resins used may also have been additionally
reacted with half-blocked isocyanates and have self-
crosslinking properties. Such resin~ are described, for
ex~mple in EP A-273 247 and US 4 692 503.
If the resin~ do not have any self-cro~31inking
groups, a Gros~linker must be added before the
dispersing.
Suitable crosslinkers for the~e re~ins are for
example urea condensation products as described in
D~-A-33 11 514 or phenolic ~annich base$ as described in
DE~A-34 22 457. EP-A-134 ~83 also ~ent~ons a~ further
possible cro~linkers blocked isocyana~es or amino re~ins
such as urea-formaldehyds resins, melamine resins or
benzoguanamine resins.
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_ 7 _ O.Z. 0062/02097
-Standard electrocoating baths may further contain
pigment pastes and cu~tomary a~sistant~. Pisment paste~
are obtainable for example from a milling resin and
pigments such as titanium dioxide, carbon black or
S aluminum silicates and also auxiliary and dispersing
agents. Suitable milling resins are described for example
in EP-A-107 089 and EP-A-251 772.
The deposition of the paint film in cathodic
electrocoating customarily takes place at 20-35C,
10preferably 26-32C, in the course of 5-500 sec, prefer-
ably 60-300 se~ at deposition voltages of 50-500 V. The
article to be coated is connected as the cathode.
Afterwards the paint films may be baked at
120 210C, preferably 140-180C.
15Ths cured cathodically deposited coats are two-
phased and, according to differential sc~nning calori-
metry (DSC) measurements, have two different ranges of
glass transition temperature~ TG. One range extends from
-70 to -20C and the other from +50 to +lOO~C, the low TG
values being due to the additions of the present inven-
tion and the high TG values to the standard binders.
The coatings of the present invention posse-
~excellent elasticity and corrosion resistance and are
highly ~uitable for u~e a3 ba~ecoats for multicoat paint
systems on which they confer no~ only good corrosion
protection properties but also good resistance to stone
chipping.
Such a multicoat paint system may compri e for
example three coat~: first a cathodically deposited
ba~ecoat, ~hen a cu~toma~y filling coa~, for example
based on polyester, and thirdly a topcoat produced from
a commercial topcoating compo~ition~
To detarmine the stone chip resist~nce of coat-
ing~ it is possible to use not only singla impact but
also multi Lmpact testers (cf. Erichsen V~ stona chip
te~ter model 508 (1983~; VW te3t method 3.14.3 (1332),
Renault test method No. 1081 (1973); DI~ 53 154 (1974),
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~ - 8 - O.Z. 0062/02097
ASTM D-2794-69; A. Zosel, farbe + lack 83 (1977), 9;
E. Ladst~dter, farbe + lack 90 (1984), 646; A 1683/83.
The paint systems with the cathodic basecoat~ of
the present invention were tested using the ~'Daimler-Benz
5pecker~ test (DIN 55 995, method A; Erich~en model 490
(1981)) at -20C.
The test was carried out on a 3-coat structure
(cathodic elec~robasecoat/filler/topcoat). Two values are
determined: the area of topcoat and filler removed in mm2
with the basecoat in~act, and the degree of rusting,
rated on a ~cale from 0 to 5, to indicate the number and
tha extent of penetrations through to the metal.
Be~ides using them a~ addition~ to Plectrocoating
baths, tha polymeric reaction products of the present
invention, or disp~rsions thereof, may also be used as
additives for other coating compositions, for example for
waterborna basecoats or coatings for pla~tics.
Preparation of polymeric reaction products of tha present
invention
General method
Preparation of epoxy-terminated butadiene-acrylonitrile
copolymers
2003 g of a carboxyl-terminated Bu/AN copolymer
having an average molecular weight ~ of 3600 and an
acrylonitrilQ content of 17 % by weight were mixed with
376 g of bisphenol A diglycidyl ether having an epoxy
equivalent weight EEW o~ about 190 by stirring and then
stirred at 130C for a further 5.5 h~ until the reaction
had ended with an acid number of ~ 1 mg of KOH/y of solid
sub~ance.
The polytetrahydrofurandiamines li~ted in Table 1
ware used a~ amino-containing polyoxyalkylene component.
The epcxy-modified butadiene-acrylonitrile
copolymer wa~ di~solved in toluen~, admixed with the
re~pective polytetrahydrofurandiamine and ~tirred for
several hours (see Table 2) at the temperature indicated
thexein until the epoxy value wa~ virtually equal to
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zero.
TABLE 1
Example Polytetrahydrofurandiamine ~ AEW
Pl Bi~(4-aminobutyl)polytetra- 5200 3117
hydrofuran
P2 Bis(3-aminopropyl)polytetra 2100 1057
hydrofuran
P3 Bi~(3-aminopropyl)polytetra- 1100 532
hydrofuran
P4 Bis(3-aminopropyl)polytetra- 750 376
hydrefuran
PS Bi~3-aminopropyl)polytetra- 350 177
hydrofuran
~ABLE 2
Example Hl H2 H3 H4 HS H6 H7 H8
Poly-THF- Pl P2 P3 P3 P4 P4 P4 P5
diamine 498.7 338.1 236.7 213.0 188.0 170.4 112.8 113.5
~g]
Epoxy- 160.0 320.0 444.4 470.6 500.0 533.3 409.5 655.2
termin-
ated Bu-
AN copoly-
mer [g]
Toluene 282.3 282.3 291.9 2~3.0 294.9 301.6 227.7 329.4
[g]
Reaction 100100 100 100100 105 105 80
tempera-
ture ~C]
Reacti~n 16 13 10 9 11 7 2 3
tLme ~h]
Amino 13.727.2 31.5 30.037.9 35.0 33.8 46.9
number
~mg of
KO~g of
solid
substance]
. ' ' ' , ;
",
:- ; . . .
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Prepara~io~ of di~persion~ Dl to D6 from polymeric
reaction products H3 to H8
General method:
The polymeric reaction productq ~3 to H8 are
diluted with the amounts of isobutanol and ethylene
glycol monobutyl ether indicated in Table 3, cooled to
40C, neutralized with acetic acid and then dispersed
with the stated amount of deionized water. Then a large
proportion of the organic solvents is distilled off azeo-
tropically under reduced pre~sure and at the same timethe solids content is adjusted with deionized water.
TABLE 3
ExampleDl D2 D3 D4 D5 D6
Amount ofH3 H4 H5 H6 H7 H8
resin solu-285.7333.3285.7333.3400.0 285.7
tion [g~
Isobutanol102.960.3102.9 60.3 265.9 73.1
~g]
Ethylena11.4 6.3 11.4 6.3 29.5 41.2
glycol
monobutyl
ether [g]
Ace~ic 3.4 3.2 4.1 3.2 3.6 5.0
acid [~]
Water [gl600.0600.0600.0600.0 600.0 &00.0
Solids 30.3 28.6 25,8 26.6 24.4 20.7
content
[% by
weightl
Electrocoating baths
A. Preparation of standard electrocoating component~ as
described in German Patent Application P 3906144.2
a) Preparation of basic re~in
al) A mixture of 5800 g of hexamethylenediamine, 7250 g
of dLmeric fatty acid and 1400 g of lin~eed oil
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fatty acid were slowly heated to 195C while the
wa~er formad (540 g~ was distilled off~ The mixture
was the~ cooled back to 100C and diluted with
5961 g of toluene to a solids content of 70 ~ by
S weight. The product had an amine number of 197 mg of
KOH/g of sub~tance.
a2) In a second ~tirred vessel~ 10 eq~ivalents of a
diglycidyl ether based on bisphenol A and epichloro-
hydrin which had an equivalent weight of 485 were
dissolved in a sclvent mixture of 1039 g of toluene
and 1039 g of isobutanol by heating. The solution
thus formed was cooled back to 60C and admixed with
30~.4 g of methylethanolamin~ and 128 g of iso-
butanol, and the temperature rose to 78~C in the
course of 5 min. 1850 g of the condensation product
obtained as per al) were added and the mixture was
heated to 80~C for 2 hours.
b) Preparation of pigment paste
525.8 g of the binder obtained as per a) ware
admixed with 168.7 g of ~utylglycol, 600 g of water and
16.5 g of acetic acid. Then 800 g of titanium dioxide,
11 g of carbo~ black and 50 g of ba~ic lead silicate were
added and ths mixture was ball milled to a particle size
of le38 than 9 ~m. Then it wa~ ad~usted with water to a
solids content of 47 % by weight.
c) Preparation of crosslinker
A mixture of 1.32 kg of toluene, 0.42 kg of
trLmethylolpropane and 0.72 kg of bisphanol A was stirred
at 60C until a h~mogeneou~ solu~ion had formed. This
solution was added to a hot mixture at 60C of 3.45 kg of
i~ophorone diisocyanato, 0.86 kg of toluene and 0.0034 kg
of dibut~ltin dilaura~e. The mixture was held a~ 60C for
2 h and then admixed with 2.0 kg of dibutylamine, the
rate of addition being adjusted in such a way that the
temperatura of the reaction mixture did not exceed 80C.
Then 1.11 kg of toluene were added and the mixture was
sub~equently maintained at B0C for 1 h.
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:
- - 12 - O.Z. 0062/02097
B. Prepar~tion of electrocoating baths
EXAMPLES Bl TO B8
700 g of the binder obtainable as per a) and
300 g of the crosslinker o~tainable as per c) were
dispersed in the presence of 19 g of acetic acid with
sufficient water to produce a dispersion having a solids
content of 31 % by weight. The organic solvents were then
distilled off azeotropically and thereafter the mixture
was adjusted with water to a solids content of 35 % by
weight.
The disper~ion thu obtained was mixed with 775 g
of the pigment paste obtainabls as per b) and varying
amounts of the dispersion~ of the present invention and
made up with water to a volume of 5000 ml.
The electrocoating baths were stirred at 30~C for
168 hour-~. Z~nc-phosphatized test panels made of steel
were connected a~ the cathode and coated for 120 second3.
These coatings were then baked at 155~C for 20 min.
The composition~ of the baths, the coating
conditions and the test re4ults are listed in Table 4.
Preparation of three-layered coat~ for determining the
stone chip resistance by DBSIT
The cathodically deposited basecoats obtained as
per 2xamples Bl ~o B8 were covered by spray application
fir~t with a filling coat then with a topcoat. The
filling coat applied was the polyester-based BA5F filler
FC 80-0100 in a thickness of from 35 to 40 ~m which was
baked at 155C for 25 min.
The topcoat wa~ a two-component high solids
topcoat FD 73-0782 fxom BASF, which was applied in a
thickness of ~5 to 40 ~m and baked a~ 130C for 30 min.
The three-layered coa~ings thus obtain~d were
sub~Qc~ed to the DBSIT s~one chip res~tance test. The
re~ults aro listed in Table 4.
20~91~ ~
- 13 - O. Z . 0062/020~7
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