Note: Descriptions are shown in the official language in which they were submitted.
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FIELD OF INVENTION_
This invention relates tc binders for cathodic
deposition electro-dip coatings. More particularly, the
invention relates to binders for cathodic deposition
electro-dip coatings which contain reaction products of
polyoxyalkylenepolyamines having secondary amino groups
with epoxide resins. The binders produced according to
the invention are especially suitable for the formulation
of electro-dip coatings, whereby films of higher layer
thickness can be obtained under normal deposition condi-
tions.
BACKGROUND OF INVENTION
In EP 0,070,550 Al, reaction products of poly-
epoxide compounds with primary polyoxyalkylenepolyamines
are described. Coatings formulated with such binders are
reported to give cathodically applicable films havinq en-
hanced cratering resistance. However, because of the poly-
functionality o~ the reactant raw materials employed, the
binders cannot be reproducibly prepared and tend to gelling
during synthesis.
EP 0,193,635 81 relates to components for cationic
electro-dip coatings based on reaction products of polyoxy-
alkylenepolyamines with monoepoxides. These products have
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pronounced hydrophilic properties and, in the hot damp test
and/or salt spray tast, demonstrate a deterioration in the
adhesion of the baked films on non-pretreated steel sheet.
It has now been found that cathodic deposition
coatings which contain, as binders, polyepoxide resins which
are modified partially with polyoxyalkylenepolyamines having
secondary amino groups will provide films of higher layer
thickness under normal deposition conditions. Moreover, the
coating bath containing the binders have good stability and
good deposition characteristics.
SUMMARY OF INVENTION
Accordingly, the present invention relates to a
process for producing binders, which are based on amine-
modified epoxide resins and are water-dilutable after com-
plete or partial neutralization with inorganic and/or or-
ganic acids. The process is characterized in that 5 to 60
mol percent, preferably 10 to 35 mol percent, of the epoxide
groups of a resin-type compound having at least two 1,2-
epoxide groups per molecule are reacted with a polyoxyalky-
lenepolyamine having secondary amino groups and the remain-
der of the epoxide groups is fully reacted at 60 to 120C
with amines and/or carboxylic acids and/or substituted
phenols, the quantity of the basic components being selected
in order that the end product has a theoretical amine number
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of at least 30 mg KOH/g, and preferably from 50 to 110 mg
KOH/g.
The invention also embraces the binders produced
and their use in the formulation of electro-dip coatings,
with which films of higher layer thickness can be obtained
even under normal deposition conditions.
The process of the invention provides products
which can be used as a binder in combination with curing
components or as the sole binder in the case of appropriate
modification with curable groups, such as half-blocked
diisocyanates, and also, due to their good pigment wetting,
for the production of pigment pastes for later blending with
other cathodic deposition electro-dip coating binders. The
process is straight forward and economical.
The resin-type compounds used, having at least
two 1,2-epoxide groups, which are reacted according to the
invention with polyoxyalXylenepolyamines having secondary
amino groups, are the commercially available epoxide resins
which are obtained by reacting bisphenols, novolaks, glycols
and the like with epichlorohydrin or methylepichlorohydrin.
A wide range of these products is commercially available.
The products based on bisphenol A or novolaks, which have
an epoxide e~livalent weight between 170 and 1000, are par-
ticularly preferred.
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The modifiers having curable groups which can be
used according to the invention are obtained by reacting
polyoxyalkylenepolyols with primary amines, for example, as
disclosed in EP 0,369,752 A2. A large number of the other
amines, carboxylic acids or substituted phenols, referred to
as "residual modifiers'l in the examples, which are reacted
with the epoxide groups remaining free in the epoxide resins
after reaction with the polyoxalkylenepolyamines having
secondary amine groups, are known to those skilled in the
art.
The binders are produced by reacting the reactant
components at 60 - 120C until free epoxide groups are no
longer detectable.
PRESENTLY PREFERRED EMBODIMENTS
The examples which follow are to illustrate the
invention, without re~triction of its scope. All the data
in parts or percent relate to weight units, unless otherwise
stated. All the data in the tables relate to 100 percent
solids.
The following abbreviations are used in the exam-
ples:
AM 1 secondary amine, prepared as follows: To a 200 ml
high pressure autoclave, 5 g of Ni-Zn catalyst
containing 50% by weight of Ni and 50~ by weight
of ZnO, 100 g of polyoxypropylene triol obtained
by addition polymeriæation of propylane oxide to
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~ 4~24
glycerol and has a hydroxyl value of 33.4 mg KOH/g
and an average molecular weight of 5040 (herein-
after abbreviated as Polyol-P) and 15.2 g o~ iso-
propylamine were successively charged. Nitrogen
substitution was carried out 5 times at the pres-
sure o~ 10 kg/cm2G and then hydrogen was charged
at the initial pressure o~ 50 kg/cm2G. The mix-
ture was heated to 220C with stirring and reacted `
for 8 hours. The pressure rose to 73 kg/cm2G.
After completing the reaction, the catalyst was
removed by filtration. The filtrate was dried
under reduced pressure to give polyoxyalkylene
polyamine having secondary amino groups at the
end of the polymer chain.
The product had a total amine value of 27.5mg KOH/g, primary amine value of 1.20 mg KOH/g,
secondary amine value of 26.1 mg KOH/g, tertiary
amine value of 0.09 mg KOH/g, and a residual hy-
droxyl value oE 4.30 mg KOH/g. Thi~ preparation
corresponds to Example 1 of EP 0,369,752 A2.
AM 2 secondary amine, prepared according to the pro-
cedure of AM 1, except that polytetramethylene-
ether glycol obtained by ring-opening polymeri-
zation of tetrahydrofuran (hereinafter abbreviated
as Polyol-R) was used in place of Polyal-P in AM
1. Polyol-R had a hydroxyl value of 112 mg KOH/g
and an average molecular weight of 1000. The
reaction pressure rose to 70 kg/cm2G. This prep
aration corresponds to Example 6 of EP 0,369,752
~2.
AM 3 secondary amine, prepared accordinq to the pro-
cedure of AM 1, except that benzylamine was used
in place of isopropylamine in ~M 1. The reaction
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pressure rose to 64 kg/cm2G, equivalent weight:
about 2240. This preparation corresponds to
Example 9 of EP 0,369,752 A2.
AM 4 secondary amine Novamin~ N 10, which is an alky-
lated polyetherdiamine, amine number: about 280 mg
KOH/g; equivalent weight: about 200.
AM 5 secondary amine Novamin~ N 20, which is a polyoxy-
propylenediamine: amine number: about 183 mg
KOH/g: equivalent weight: about 300.
DEA diethylamine
DEAPA 3-diethylamino-1-propylamine
EPH I epoxide resin based on bisphenol A and epichloro-
hydrin having an epoxide equivalent of About 200
EPH II epoxide resin based on bisphenol A and epichloro-
hydrin having an epoxide equivalent of about 500
MP methoxypropanol
EP ethoxypropanol
NPH nonylphenol
TDI toluylene diisocyanate (commercial isomer mixture
with 80% of 2,4-TDI)
SPH reaction product of one mol of phenol with 2 mol
of DEAPA and 2 mol of formaldehyde and also w.ith
2 mol of a TDI half-blocked with 2-ethylhexanol
(MW = 986)
H 1 reaction product of one mol of trimethylolpropane
with 3 mol of a TDI half-blocked with MP (urethane
crosslinking agent~
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H 2 transesterification curing agent which is the
reaction product of 3 mol of dimethyl malonate and .
1 mol of trimethylolpropane
(H 1 and H 2 are used if the initial binders do not
have self-crosslinking properties)
Sn tin catalyst (dibutyltin dilaurate), calculated as
metal
Pb lead catalyst (lead octoate), calculated as metal
:
The starting materials for the binders produced
according to the invention are summarized in Table 1.
In a suitable reaction vessel, all the components
are mixed at 60C. The temperature is slowly raised to 80C
and, if necessary, up to 120C and held until free epoxide
groups are no longer detectable.
Table 1 is as follows:
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Z ~~ a~ ~1 ~ ~D ~O O
N ~t) CO 10 t` ~ N ~o
3~
~ P. a z~ 5: ~ $ u~ ~ ei E~ r~ ~
.,1 _ _ __ ~ _ ~ _ ~ _ ~ ~ ~
~ ~ o c~ o In u~ ~ o o o ~ o o
O N O~ N ~ ~ f~l ~ q~ ~ r~l
~ -- -- -- -- -- -- -- -- -- -- ~ -- --
~,~ ~: O ~Or~ o ~ a~ u~ ~o o ~ o ~o
u~ ~ ~ r~t~ ~ ~o ~o o~ ~r ~ ~ ~ ~
K :1 ~ ,1~ ,~ N a~ ~1 N N -~ ~1
~1 N ~ rl N ~r m
~1 ~ E~~ ~ ~ ~ ~ ~ ~ ~
m ~ ~ ,~ ~ _ ,_ ~ _ ,~
tJ~ N O O co O O oo O
_ O N _ O _ _ _ N
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~ O N N O O O . O
U~ ~ oO ~ ~ ~ ~O O ~ O
::~ O ~1 N U~ If ~ 'r U~ U~
O~
H H H H H H
H H H H H H H H H H
X ~ ~ :1: ~ 5
W ~ ~ ~ ~ W
_
a~ ~ o o u~ In o o o o o o
~ ~ ~1 ~ ~P 1 ~i ~ ~r ~r ~r ~o
X _ _ _ ~, ~_ _ _ _ _ ~_ `._
O ~
O O Cl O O O O O O O
~J O O O. U~ O O O O O O
:~ N O G~ `t O ON
~3 ~1 N ~ ~ U~ to r~ cl~
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The binders produced according to Table 1 are
mixed in the weight ratios indicated in Table 2 with the
crosslinking agent and the catalyst. The quantity of the
neutralizing agent Eor producing a stable aqueous cle~rcoat
(in millimol of formic acid/100 g of solid resin) is indi-
cated in the last column of the table.
Table 2 is as follows:
Table 2
Binder Parts of Solid Matter Catalyst NeutralizationCombination
(BK) Binder Cross-
(from linking
Example)* agent
1 100(4)/ -- 1.0 Sn 40
65 EP
. .
2 70(2)/30 H 1 1~0 Sn 35
60 EP
__ . . ... ,, _ :
3 75(3)/25 H 2 1.2 Pb 40
70 MP
4 70 (1)/ 30 H 1 0.8 Sn 35
65 MP
100(5)/ 20 H 1 1.0 Sn 30
60 MP
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6 75(6)/25 H 1 0.8 Sn 35
60 MP
7 80(7)/~0 H 1 1.0 Sn 40
65 MP
_ _ _ .
8 70(~)/30 H 1 0.8 Sn 35
65 MB
.
* The data relate to the percentage content and
to the solvent containing the binder.
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For producing pigmented coatings, the binder
combinations 1 - 5 are processed in accordance with the
following formulation:
100.0 parts of solid resin
0.5 part of carbon black pigment
3.3 parts of basic lead silicate pigment
35.5 parts of titanium dioxide
5.0 parts of monoethylene glycol monohexyl ether
The pigmented coatings are tested by electro-
deposition on non-phosphated, degreased steel sheet which
is connected as the cathode. The films are then baked for
25 minutes at 180C, and they are tested for 360 hours for
their resistance in the salt spray test according to ASTM.
Table 3 summarizes the respective data. A cath-
odic deposition electro-dip coating according to Example 1
of EP 0,193,685 Bl was used as a comparison example (V).
Comparison example (V) is a resin mixture prepared
by blending the following ingredients:
Inaredients Parts by Weight
Pigment Paste L 210
Deionized water 1474
Cationic Resin A 1316
The cationic electrodeposition bath using thi~ mixture had
a pH of 6.6 and a resistivity at 20C of 660 ohm cm 1.
Cationic Resin A was prepared from the following
mixture of ingradients:
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2sss/us3s70
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In~redientsParts by WeiqhtSolids
EPON 8291 702.2 702.2
PCP-02002 263.4 263.4
Xylene 61.6
Bisphenol A 197.8 197.8
Benzyldimethylamine 3.8
Capped isocyanate crosslinker3 891 629.1
Diketimine derived from
diethylenetriamine and methyl
isobutyl ketone (73% solids in
methyl isobutyl ketone)75.3 54.7
N-methylethanolamine 59.1 59.1
Phenoxypropanol 126.9
Acetic acid 29.5
Cationic surfactant429.3
Deionized water 2553.1
1 Epoxy resin made from reacting epichlorohydrin and
bisphenol A having an epoxy equivalent of 188 commercially
available from Shell Chemical Company.
2 Polycaprolactone diol available from Union Carbide
Corporation.
3 Polyurethane crosslinker formed from half-capping
toluene diisocyanate (80/20 2,4-/2,6-isomer mixture) with
2-ethylhexanol and reacting this product with trimethylol-
propane in a 3:1 molar ratio. The crosslinker is present as
a solution in 2-ethoxyethanol.
4Cationic surfactant prepared by blending 120 parts of
an alkyl imidazoline commercially available from Geigy
Industrial Chemicals as GEIGY AMINE C) 120 parts by weight
of an acetylenic alcohol commercially available from Air
Products and Chemicals as SURFYNOL 104, 120 parts of 2-
butoxyethanol and 221 parts by weight of deioni~ed water and
19 parts of glacial acetic acid.
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2595/Us357~
2al~9~ 4
The EPON 829, PCP-0200 and xylene were charged to
a reaction vessel and heated under a nitrogen atmosphere to
210C. The reaction was held at reflux for about ~ hour to
remove water. The reaction mixture was cooled to 150C and
the bisphenol A and 1.6 parts of the benzyldimethylamine
(catalyst) added. The reaction mixture was heated to 150-
190C and held at this temperature for about 1~ hours and
then cooled to 130C. The remaining portion of the benzyl-
dimethylamine catalyst was added and the reaction mixture
held at 130C for 2~ hours until a reduced Gardner-Holdt
viscosity (50 percent resin solids solution in 2-ethoxy-
ethanol) of P was obtained.
The polyurethane crosslinker, the diketimine
derivative and the N-methylethanolamine were then added
and the temperature of the reaction mixture brought to
110C and held at this temperature for 1 hour.
The phenoxypropanol was added and the reaction
mixture was dispersed in water by adding the reaction mix-
ture to a mixture of the acetic acld, deionized water and
the cationic surfactant.
Pigment Paste L was prepared from the following
mixture of ingredients:
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Ingredients Parts by Weiqht
Titanium dioxide 44.42
Lead silicate 2.9
Carbon black 0.37
Pigment Grinding Vehicle of Example J 18.5
Deionized water 27.51
Catalyst Paste as described above 6.3
The above ingredients were ground in a mill to a
Hegman No. 7 grind.
Table 3 is as follows:
Table 3
Coatinq Layer Thickness ~ml) Salt Spray Test mm
1 38 1.5
2 32 2
3 43 2.5
4 33 1.5
31
6 34 2.5
7 36 2
8 32 1.5
V 24 6.5
1) Maximum obtainable layer thickness at 32C bath
temperature and 135 seconds.
2) Disbonding after a test period of 360 hours.
As will be apparent to one skilled in the art,
various modi~ications 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.
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