Note: Descriptions are shown in the official language in which they were submitted.
CA 022130~6 1997-08-1~
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OH-terminated, uretdione-functional polyisocyanates, a process for
their preparation, and their use
The invention relates to OH-terminated, uretdione-functional polyisocyanates
5 having a functionality of > 2 to < 3, to a process for their preparation, and to
their use for preparing polyurethane (PU) polymers, especially PU coating
systems which are free from elimination products, very preferably of
transparent and pigmented PU powder coating systems, and to the colorfast
and weather-stable PU coatings produced accordingly.
Polyisocyanates for use in polyurethane powder coatings, containing
uretdione groups, are known in particular from DE-A-30 30 554.
Polyisocyanates of that kind, however, have only two terminal, partly or
completely blocked isocyanate groups, and are strictly linear in structure. As
l 5 is evident from EP-A 254 152 (page 2, column 1, line 63 to end of sentence),
this fact is a great disadvantage in practice.
The teaching of EP-A 639 598, too, is based on.the polyaddition reaction of
uretdione-functional polyisocyanates with diols and/or bifunctional chain
2 o extenders and, as is evident from the examples, with monoalcohols. Even the
use of isocyanurate-functional polyisocyanate-uretdiones having more than
two NCO functions does not - owing to the use of monoalcohols - lead to
more highly functional polyaddition products, the crosslinkers for PU powder
coatings. However, as mentioned above, this is disadvantageous for the
2 5 quality of the coatings.
In accordance with DE-A-19 505 566, surprisingly, it was possible for the first
time to use polyols having more than two hydroxyl groups to prepare the
claimed uretdione-functional polyisocyanates. To do this, however! it was
3 o first of all necessary partly to block the isocyanate groups of the
polyisocyanate-uretdiones, in order to avoid gelling. On economic grounds,
re-eliminable blocking agents were employed. However, this constitutes an
ecological disadvantage.
CA 022130~6 1997-08-1~
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The object of the present invention, therefore, was to provide uretdione-
functional polyisocyanates, in order to use these crosslinkers to prepare PU
polymers, in particular ecologically useful PU powder coatings, which are
free from elimination products, and the PU powder coatings produced
5 accordingly which no longer have the abovementioned disadvantages of the
prior art.
This object has been achieved in accordance with the claims.
lO The present invention accordingly provides hydroxyl- and uretdione-
functional polyisocyanates essentially comprising
A) from 55 to 86% by weight of uretdione,
B) from 1.5 to 15% by weight of polyol with 2 3 hydroxyl groups, and
lS C) from 7.0 to 30% by weight of diol,
the polyaddition products carrying terminal hydroxyl groups and having a
functionality of > 2 to < 3, preferably between 2.1 and 2.9, molar masses of
between 1600 and 15,000, preferably between 1900 and 10,000, and a free
20 isocyanate content of < 0.5% by weight.
The invention additionally provides for the use of the hydroxyl- and
uretdione-functional polyisocyanates for preparing PU polymers, especially
in combination with hydroxyl-containing polymers, in transparent and pig-
2 5 mented PU powder coatings which are free from elimination products and are
of increased network density, very good reactivity and excellent gloss, and
provides transparent and pigmented PU powder coatings which are free from
elimination products and comprise the novel hydroxyl- and uretdione-
functional polyisocyanates having a functionality of > 2 to < 3.
The uretdiones (component A) employed in accordance with the invention
are obtained from diisocyanates by known methods, and in principle it is
possible to employ all known diisocyanates.
CA 022130~6 1997-08-1~
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Preferred uretdiones, however, are derived from the diisocyanates selected
from the group consisting of hexamethylene diisocyanate (HDI),
2-methylpentamethylene 1,5-diisocyanate (Dl 51), 2,2,4(2,4,4)-trimethylhexa-
methylene diisocyanate and isophorone diisocyanate (IPDI), which
5 isocyanates can be employed individually or in mixtures as component A.
Particular preference is given to the use of the uretdione of isophorone
diisocyanate.
10 The isocyanurate-free uretdione of isophorone diisocyanate has a high
viscosity at room temperature of more than 106 mPa s; at 60~C the viscosity
is 13 103 mPa s and at 80~C it is 1.4103 mPa s. The free NCO content is
between 16.8 and 18.5% by weight; in other words, more or less high
proportions of the polyuretdione of IPDI must be present in the reaction
15 product. The monomer content is ~ 1% by weight. The overall NCO content
of the reaction product after heating at 180 - 200~C is 37.4 - 37.8% by
weight.
The dimerization of aliphatic diisocyanates using conventional processes
2 o and catalysts produces, as a byproduct, varying amounts of isocyanurate, so
that the NCO functionality of the isocyanurate-containing polyisocyanate-
uretdiones employed is from > 2 to 2.5. As a result it was very surprising that
such isocyanurate-containing polyisocyanate-uretdiones could be used for
the synthesis of hydroxyl- and uretdione-functional polyisocyanates having
25 a functionality of from > 2 to < 3 without the occurrence of gelling.
Suitable polyols (component B) in accordance with the invention are glycerol,
trimethylolpropane, ditrimethylolpropane, trimethylolethane, 1,2,6-
hexanetriol, 1,2,4-butanetriol, tris(~-hydroxyethyl)isocyanurate, penta-
30 erythritol, mannitol or sorbitol, with preference being given to the use oftrimethylolethane, trimethylolpropane (TMP) and trishydroxyethyl
isocyanurate (THEIC). They are used individually or in mixtures.
The diols (component C) employed in accordance with the invention include
CA 022130~6 1997-08-1~
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all those which are commonly employed in PU chemistry; particular
preference is given to ethylene glycol (E), triethylene glycol (TEG),
1,4-butanediol (B), 1,5-pentanediol (P), 1,6-hexanediol (HD), 3-methyl-1,5-
pentanediol (Pm), neopentylglycol (N), 2,2,4(2,4,4)-trimethylhexanediol (T)
5 and neopentylglycol hydroxypivalate (Eg).
The novel polyisocyanates advantageously also comprise chain extenders
(component D) having a functionality of from 2 2 to < 6, in particular 2 2 to
< 4, in the form of linear and/or branched hydroxyl-containing polyesters
and/or polycaprolactones having a molar mass of between 180 and 2000,
preferably between 230 and 1500, and hydroxyl numbers of between 900
and 50 mg of KOH/g, preferably between 700 and 100 mg of KOH/g. They
are prepared, for example, by the condensation of polyols or diols and
dicarboxylic acids.
Preferred chain extenders employed are linear hydroxyl-containing
polycaprolactones having a molar mass of between 180 and 2000 and a
hydroxyl number of between 625 and 50 mg of KOH/g.
20 Further preferred chain extenders used are branched polyesters or
polycaprolactones having a functionality 2 3, a molar mass of between 210
and 2000 and a hydroxyl number of between 900 and 100 mg of KOH/g.
The chain extenders are prepared using, preferably, the abovementioned
2s polyols and/or diols, supplemented by 2-methyl-1,3-propanediol, diethylene
glycol, 1,12-dodecanediol and also trans- and cis-cyclohexanedimethanol
(CHDM).
The preferred dicarboxylic acids include aliphatic acids with or without alkyl
30 branching, such as succinic, adipic (As), suberic, azelaic and sebacic acid
(Sb), and 2,2,4-(2,4,4)-trimethyladipic acid; also covered by this definition are
lactones and hydroxycarboxylic acids, such as c-caprolactone and
hydroxycaproic acid.
CA 022l30~6 l997-08-l~
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The novel hydroxyl-containing reaction products - components B, C and D -
are employed such that the mixtures must include at least 1 mol of B and/or
D having three or more OH groups in the OH mixture.
5 The novel mixing ratio of the hydroxyl-containing reactants to the uretdione
must be chosen such that the functionality of the hydroxyl- and uretdione-
functional polyisocyanates is between > 2 and < 3.
The novel polyaddition products can be obtained, inter alia, by the process
10 described below.
Reaction in solvent generally takes place at temperatures from 50 to 100~C,
preferably between 60 and 90~C. The OH component, polyol and/or diol
and/or chain extender, is introduced as initial charge and the uretdione is
l 5 added as rapidly as possible but without the reaction temperature surpassingthe abovementioned limits. The reaction is over after from 30 to 150 minutes.
Subsequently, the solvent is removed. Apparatus suitable for this purpose
comprises evaporating screws, filmtruders or else spray-driers.
20 Suitable solvents are benzene, toluene or other aromatic and/or aliphatic
hydrocarbons, acetates, such as ethyl acetate or butyl acetate, and also
ketones, such as acetone, methyl ethyl ketone and methyl isobutyl ketone, or
chlorinated aromatic and aliphatic hydrocarbons, and also any desired
mixtures of these or other inert solvents.
The invention also provides the solvent-free and continuous preparation of
the process products by means of thorough kneading in a single- or
multiscrew extruder, especially in a twin-screw extruder. The solvent-free
synthesis requires temperatures from 2 1 10 to 1 90~C. It was surprising that
30 it is possible to employ such high temperatures for the uretdione syntheses.
Such temperatures are already well within the range in which uretdiones
unblock, so that high free isocyanate contents may result and hence
uncontrolled reaction processes would be expected. This fact was significant
for the synthesis of the hydroxyl-containing uretdione polyaddition product,
CA 022130~6 1997-08-15
.
- 6 - o. z . 5088
and it was all the more surprising that it could be realized. In this context, the
short reaction times of < 5 minutes, preferably < 3 minutes, in particular < 2
minutes, proved to be advantageous.
s It is also a matter of principle that the brief thermal exposure is sufficient to
provide for homogeneous mixing of the reactants and, at the same time, for
their complete or substantial reaction. Subsequently, controlled cooling is
carried out in accordance with the establishment of equilibrium, and, if
necessary, conversion is completed.
The reaction products are supplied to the kneading apparatus in separate
product streams, it being possible to preheat the starting components to
120~C, preferably to 90~C. Where there are more than two product streams,
they can also be metered in in clusters. Polyol and/or diol and/or chain
15 extender and/or catalysts and/or further customary coatings additives, such
as leveling agents and/or stabilizers, can be combined into one product
stream; the same applies to those which are inert toward isocyanate groups:
catalysts and corresponding abovementioned coatings additives.
20 Similarly, the sequence of the product streams can be varied, and the entry
point of the product streams may be different.
For afterreaction, cooling, comminution and bagging, known techniques and
technologies are employed.
To accelerate the polyaddition reaction it is also possible to use the catalystswhich are customary in PU chemistry. They are employed in a concentration
of from 0.01 to 1% by weight, preferably 0.03 to 0.5% by weight, based on
the reaction components used. Tin(ll) and (IV) compounds have proven
30 particularly suitable to date. Among these, particular mention is made of
dibutyltin dilaurate (DBTL). However, other catalysts should not immediately
be regarded as unsuitable.
The present invention provides, furthermore, for the use of the hydroxyl- and
CA 022130~6 1997-08-1~
.
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uretdione-functional polyisocyanates for preparing polyurethane polymers,
especially in combination with hydroxyl-containing polymers and/or with the
additives customary in PU chemistry, for preparing transparent and
pigmented PU powder coatings which are free from elimination products,
s have very good reactivity and are therefore economically and ecologically
significant, and, surprisingly, possess excellent flexibility despite an
increased network density.
The present invention also provides PU powder coatings which are free from
10 elimination products, consisting of the novel polyisocyanates in combination
with hydroxyl-containing polymers. Suitable reactants for PU powder
coatings are compounds which carry those functional groups which, during
the curing process, react with isocyanate groups as a function of temperature
and time, examples being hydroxyl, carboxyl, mercapto, amino, urethane and
15 (thio)urea groups. Polymers which can be employed are addition polymers,
condensation polymers and polyaddition compounds.
In principle it is possible to use any polymer which contains more than two
OH groups and melts at at least 70~C. These are polyetherpolyols,
20 polyesteramidepolyols, polyurethanepolyols, hydroxylated acrylate resins,
etc., whose OH groups are intended for crosslinking with the novel,
uretdione-functional polyisocyanates. Among the numerous possibilities for
hydroxyl-containing polymers within the framework of the invention, particular
preference is given to polyesterpolyols. The hydroxyl-containing polyesters
2s which are employed with particular preference have an OH functionality of
> 2, an OH number of from 20 to 200 mg of KOH/g, preferably 30 to 150 mg
of KOH/g, a viscosity of < 60,000 mPa s, preferably < 40,000 mPa s, at
160~C, and a melting point of from > 70 to < 120~C, preferably from 75 to
100~C.
Polyesters of this kind can be obtained in a manner known per se by
condensation in an inert-gas atmosphere at temperatures of from 100 to
260~C, preferably 130 to 220~C, in the melt or in an azeotropic procedure,
as is described in Methoden der Organischen Chemie (Houben-Weyl), Vol.
CA 022130~6 1997-08-1~
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14/2, 1 - 5, 21 - 23, 40 - 44, Georg Thieme Verlag, Stuttgart, 1963, or in C.R.
Martens, Alkyd Resins, 51 - 59, Reinhold Plastics Appl. Series, Reinhold
Publishing Comp., New York and in DE-A-19 57 483, 25 42 191, 30 04 876
and 31 43 060.
The mixing ratio of the hydroxyl-containing polymers and the novel
polyisocyanates is generally chosen such that there is 0 5 - 1.2, preferably
0.8 -1.1, very preferably 1.0 NCO group per OH group.
10 In order to increase the rate of gelling of the heat-curable powder coatings it
is possible to add catalysts. Catalysts used are organotin compounds such
as dibutyltin dilaurate (DBTL), Sn(ll) octoate, dibutyltin maleate, etc. The
amount of catalyst added is 0.1 - 5 parts by weight per 100 parts by weight
of the hydroxyl-containing polyester.
To prepare PU powder coatings, the isocyanate component is mixed with the
appropriate hydroxyl-containing polymer and, if desired, with catalysts and
pigments and with customary auxiliaries, such as fillers and leveling agents,
such as silicone oil and acrylate resins, and the mixture is homogenized in
20 the melt. This can be done in suitable equipment, for example heatable
kneading apparatus, but preferably by extrusion, in the course of which
upper temperature limits of 130 to 140~C should not be exceeded. The
extruded mass is cooled to room temperature, is comminuted suitably, and is
then ground into the ready-to-spray powder. The ready-to-spray powder can
2 5 be applied to appropriate substrates in accordance with the known methods,
for example by electrostatic powder spraying, fluidized-bed sintering, or
electrostatic fluidized-bed sintering. Following the application of the powder,
the coated workpieces are cured by heating them at a temperature of from
150 to 220~C for from 60 to 4 minutes, preferably at from 160 to 200~C for
30 from 30 to 6 minutes.
In the text below the subject-matter of the invention is illustrated in more
detail with reference to examples.
CA 022130~6 1997-08-1~
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The abbreviations used are explained in the description at the appropriate
points (pages 3 to 4).
A Preparation of the novel hydroxyl- and uretdione-functional
s polyisocyanates
A1 Polyol chain extenders
General preparation procedure
The starting components - cf. Tables 1 and 2 - are placed in a reactor and
are heated to ~ 140~C with the aid of an oil bath. After the substances have
for the most part melted, 0.1% by weight of di-n-butyltin oxide is added as
catalyst. Initial elimination of water takes place at from 150 to 160~C. Over
15 the course of 2 to 3 hours the temperature is raised from 180 to 190~C, and
esterification is completed over the course of a further 8 to 10 hours.
Throughout the reaction period, the bottom product is stirred and a gentle
stream of nitrogen is passed through the reaction product. The acid number
of the polyesters was always < 2 mg of KOH/g.
CA 02213056 1997-08-15
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CA 022130~6 1997-08-1~
- 12 - O. Z . 5088
A 2 Hydroxyl- and uretdione-functional polyisocyanates
General preparation procedures
A 2.1 From solvent
The polyol component - cf. Table 3 - and the catalyst (0.03 - 0.5% by weight
of DBTL) are introduced as initial charge, dissolved in the solvent, to the
reactor. With vigorous stirring and under an inert-gas atmosphere the
calculated amount of uretdione, dissolved in the solvent, is added at a rate
such that the reaction temperature does not exceed 100~C. The reaction is
monitored by means of titrimetric NCO determination and is over after 1 to 3
hours. The solvent is subsequently removed and the product is cooled and,
if appropriate, comminuted.
A 2.2 Without solvent
The uretdione was fed, at a temperature of from 60 to 1 1 0~C, into the intake
barrel of a twin-screw extruder, the polyol component - cf. Table 3 - being
metered in simultaneously at a temperature of from 25 to 110~C. The
uretdione and/or the polyol component contained, if appropriate, the required
amount of catalyst: from 0.03 to 0.5% by weight of DBTL, based on the end
product.
2 5 The extruder employed is composed of ten barrels, of which five are heating
zones. The temperatures of the heating zones cover a wide range - between
50 and 190~C -and can be controlled individually. All temperatures are
setpoint temperatures; regulation within the barrels is accomplished by
means of electrical heating and pneumatic cooling. The die element is
heated by means of an oil thermostat. The rotary speed of the twin screw,
fitted with conveying elements, was between 50 and 380 rpm.
The reaction product, obtained at a rate of from 10 to 130 kg/h, is either
cooled and then comminuted or shaped and bagged, or the melt itself is
CA 022130~6 1997-08-1~
- 1 3 - O . Z . 5088
shaped, cooled and bagged.
The physical and chemical characteristics of the novel process products, and
the molar compositions, are summarized in Tables 3 to 5
s
The uretdiones, prepared by known processes, had the following
characteristics:
IPDI uretdione
free NCO: from 16 8 to 18 5% by weight
total NCO: from 37 4 to 37.8% by weight
Dl 51 uretdione
free NCO: from 20 1 to 21.2% by weight
total NCO: from 43 7 to 44 9% by weight
HDI uretdione (DESMODUR(~) N 3400)
free NCO: from 20 9 to 22 1% by weight
total NCO: from 35 6 to 36 5% by weight
- 14 - o . z . 5088
Table 3: Hydroxyl- and uretdione-functional polyisocyanates
Example Composition in n-ol Chemical and physi al ~I a ~ ics
Zuretdione polyol diol(s)chain e)tender NCO content melting range glass transition temperature
comp. Acomp. Bcomp. C componert D ~% y wt.l l~C~ [~C~
IPDI F = 2 F = 3free total
1 3.1 TMP(1)E (2.6) A 1.1.3 (0.5) - 0 8.085-88 49-58
2 3.2 TMP(1)E (2.7~ A 1.1.3 (0.5) - 0 8.490-91 53-67
3 4 TMP(1~B (3.5~ A 1.1.1 (0.5~ - 0 9.8100-105 58-71 D
4 6 TMP(1) E(5) A1.1.2(1~ - 0 11.8 93-97 55-67
8 TMP(1~ HD(7~ A1 1 3(1~ - 0 11.8 94-97 59-69 ~
0 6 9 TMP(1~ B(9~ - - ~ 13.3 135-138 99-115 C'
7 9 TMP(1)Pm (9) - - O 12.1 123-126 96-108
8 9 TMP(1) ~D(9) ~ ~ ~ 12.1 120-123 96-110
9 9 TMP(1) T(9~ - - ~ 11.7 116-119 90-101
9 TMP(1) Eg(9) o 11.2 113-116 89-107
11 9 TMP(1) B(5~ 0 12.5 126-129 97-112
Pm(4~
- 15 - o. z . 5088
Table 3: continued
Example Composition in n ol Chemical and physi al ~I,a,.n,t~ ,i,li-,,
A 2uretdione polyol diol(s)chain extender NCO contentmelting range glass transition temperature
comp. Acomp. Bcomp. C componert D ~% y wt.~ I'C] [~C]
IPDI F = 2 F = ~ 3free total
12 9 TMP(1)B(7) A1.1.1 (2) - 0 12.5 117-120 78-101
13 9 TMP(1)B(7) A1.1.3(2) - 0 11.7 98-104 51-69
14 10 TMP (1)B (8.5)A 1.1.3 (1.5) - o 12.5 106-109 67-86
15 10 TMP(1)B(7.5) A1.1.3(2.5) - 0 11.6 93-96 56-71
16 11 TMP(l)B(9.5) A1.1.1 (1.5) - 0 13.4 120-123 91-107
0 17 11 TMP(1)B(4) A1.1.1 (7) - O 11.2 91-94 53-69
18 11 TMP(1)B(9) A1.1 3(2) - o 12.4 91-94 45-63
o
- 16 - o. z . 5088
Table 4: Hydroxyl- and uretdione-functional polyisocyanates
Example Composition n mol Chemical and physic-l cl,~ s
A2uretdione polyol diol(s)chain extender NCO content melting range glass transition temperature
comp. Acomp. Bcomp. C componentD 1% -ywt.~ [~C~ 1~C
IPDI F=2 F='3 free total
1 4 - E (4) - A1.2.2(1) 0 9.2 98-101 55-68
2 6 - Pm (6) - A1.2.2(1) 0 10.5 105-109 57-71
3 6 - E(5) A1 1 1(l)A1.2.2(1) 0 10.8 97-100 56-67 D
4 6 - E (6) - A1.2.3(1) 0 9.2 95-97 50-70
5 7 - B (7) - A1.2.3(1) 0 9.7 93-96 48-69
0 6 7 - B (7) - A1.2.2(1) 0 11.5 105-108 77-91
7 7 B(6) A1.1.1(1)A1.2.2(1) 0 11.1 91-95 40-65 ~
8 8 - B (7) A1.1 3(1)A1 2 1(1) o 10.5 73-76 21-41 o
9 8 - B (6) A1 1 1(2~A1.2.3(1) 0 9.6 91-94 47-69
10 9 - B (8) A1 1.1(1)A1.2.2(1) 0 12.3 106-109 75-92
- 17 - C~. Z . 5088
Table 4: continued
Example Composition in mol Chemical and physi aN,llal~ll,l.:li,lil,,
A 2uretdione polyol diol(s)chain extenderNCO contentmelting range glass transition temperature
comp. Acomp. Bcomp. C compon nt D i% bywt.] [~C1 [~C~
IPDI F = 2 F= a 3 free total
11 9 - B (7.5) A 1.1.3 (1.5)A 1.2.2 (1) 0 11.4 93-96 59-77
12 9 ~ E(8) A1.1.4(1)A1.2.2(1) 0 11.2 83-88 44-55
9 HD(8) A1.1.1 (1)A1.2.2(1) 0 11.8 99-104 57-72 D
14 10 - Pm(8) A1.1.3(2)A1.2.2(1) 0 11.1 98-101 53-70 ~
15 10 - B (7.5) A 1.1.3 (2.5)A 1.2.1 (1) 0 10.9 86-89 49-64 o
0 16 10 ~ B(3) A1.1.1 (7)A1.2.1 (1) 0 10.0 73-76 41-55
17 10 - P(675) A1.1.1 A1.2.2(1) 0 12.2 110-113 84-102
B (2) (1.25)
18 11 - B(10) A1.1.3(1)A1.2.2(1) 0 11.9 87-90 51-66
19 11 - B(8.5) A1.1 3(25)A1.2.2(1) 0 11.5 83-86 44-58 u
20 12 - B (7) A 1.1.1 (5)A 1.2.3 (1) 0 10.5 93-96 57-70
- 18 - o. z . 5088
Table 5: Hydroxyl- and uretdione-functional polyisocyanates
Example Composition in mol Chemical and physic I ~I,a,~n,lt:,i,Iics
A 2ure~dione polyol diol(s)chain extenderNCO content melting range glass transiUon temperature
comp. Acomp. Bcomp. C compon nt D 1% y wt.] [~C] I-C]
IPDI/DI 51 F = 2 F = ~ 3 free totai
1 5 50.5TMP(1)E (5)A 1.1 2 (1) - 0 11.5 85-87 41-63
2 7.51.5TMP(1)B (7)A 1.1.1 (2) - 0 12.6 89-93 59-73
3 9 1TMP(1)P(6.75)A1.1.1 (1.25) - o 13.2 116-118 78-95 D
B (2)
4 8 2 - Pm ~9)A 1.1.3 (1) A 1.2.2 (1) 0 12.0 80-84 49-62 ~"
1TMP(1)B(9)A 1.1.3 (2) - O 12.6 79-86 45-59 u
IPDI/HDI
66.5 0.5 - B (n - A 1.2.2 (1) 0 11.3 89-94 57-69
7 8 1 - B (8)A 1.1.1 (1) A 1.2.2 (1) 0 11.6 83-89 56-67
8 9 1TMP(1)B (8.5)A 1.1.3 (1.5) - 0 12.0 86-90 56-70
CA 02213056 1997-08-15
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CA 022130~6 1997-08-1~
- 2 0 - O . Z . 5088
C Polyurethane powder coatinqs
General preparation procedure
S The comminuted products - uretdione-functional polyisocyanates
(crosslinkers), polyesters, leveling agent masterbatch and, if appropriate,
catalyst masterbatch - are intimately mixed together, if desired, with the whitepigment in an edge runner mill and then are homogenized in an extruder at
not more than 130~C. After cooling, the extrudate is fractionated and ground
lO to a particle size < 100 ,um using a pin mill. The powder thus prepared is
applied to degreased and optionally pretreated iron panels using an
electrostatic powder spraying unit at 60 kV, and the panels are baked in a
convection drying oven at temperatures between 170 and 200~C.
15 Levelin~ aqent masterbatch
10% by weight of the leveling agent - a commercially available copolymer of
butyl acrylate and 2-ethylhexyl acrylate - in the corresponding polyester are
homogenized in the melt and, after solidifying, are comminuted.
Catalyst masterbatch
5% by weight of a catalyst - DBTL - in the corresponding polyester are
homogenized in the melt and, after solidifying, are comminuted.
The abbreviations in the tables below denote:
LT = layer thickness in ,um
El = Erichsen indentation in mm (DIN 53156)
CH = crosshatch test (DIN 53 151)
GG 60~ ~ = Gardner gloss (ASTM-D 5233)
Imp.rev. = impact reverse in g m
HK = Konig hardness in sec (DIN ~3157)
- 2 1 - o. z .5088
C 1 Piqmented powder coatinqs
Table 7:
S ExampleC1 l 2 3~~ 4 5 6 7 8 9 10 11 12
Formulation
CrosslinkerA2 27.2424.93 20.99 15.2622.1717.6213.7722.36 21.23 27.58 26.27 16.19
Table 3 Ex. 0 (4) (6) (6) (6~ (9) (10)(12) (13)(14' (16) (18) (18) D
Polyester B 1 72.7675.07 79.01 ~ - - 72.42 73.73 - o
Polyester B 2 - - - - 77.83 - - 77.6478.77 - - - ~
Polyester B 3 - - - 84.74 - 82.3886.23 - - - - 83.81 ~n
Notes All formulations contain 40% by weight of TiO2 (white pigment) and 0.5% by weight each of leveling agent and benzoin, and also 0.15% by weight of DBTL; the OHINCO ratio I--
is 1 :1; o) OH/NCO = 1 :0.8 ~
Coatings data ~
LT G4-79 59-6763-7065-7658-70 56-63 67-79 61-7254-72 79-9970-85 61-90
GG 60~t89-90 90 90 90-9188-89 87-89 89/9088-90 91 91 91 90-91
CH 0 0 0 0 0 0 0 0 0 0 0 0
El 9 7/10> 10~ 10> 109 7/10> 10 9 6/9 9> 109 3/> 10 > 10 > 10 9 1/10
Irop.rrv 576>94468064>94468064 691.2 5768064 4608 576 691 2 4608
Notes Curing conditions: 200~C/8 to 10', 180~C/15 or 170~C/25'
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C 1 Piqmented powder coatinqs
Table 8:
ExampleC1 1 2 3 4 5 6~~ 7 8~~ 9 10 11 12~~
Formulation
CrosslinkerA218.1627.75 22.66 24.29 16.28 13.48 22.81 19.12 28.47 16.41 27.07 22.90
Table4E~ () (3) (6) (6) (8) (10) (10) (11) (11) (17) (17~ (18) (18) D
Polyester B 1 - 72.25 - - - - - - 71.53 - 72.93 77.1 o
1 0 Polyester B 2 - - 77.34 75.71 - - 77.19 80.88 - - - - ~
Polyester B 381.84 - - - 83.72 86.52 - - - 83.59 - - ~n
Notes All formulations contain 40% by weight of TiO2 (white pigment) and 0.5% by weight each of leveling agent and benzoin, and also 0.15% by weight of DBTL; the OH/NCO ratio I--
is 1 :1; o) OH/NCO = 1 :0.8
Coatings data ~
LT 61-6956-67 59-70 59-81 66-85 63-75 59-8563-8767-8862-70 80-92 85-97
GG 60~~189 89-90 89 88/8988-91 91/9290-9290-9290-9190-91 90-91 91
CH 0 0 0 0 0 0 0 0 0 0 0 0
El ~ 10> 10 > 109.4/989.0/108.7/96> 1095/10 > 108.9/10 > 10 9.6/10
Imp.rev806 4 > 944.6> 944.6 345.6345.6230.4 576 460.8 691.2 345 6 576 345 6
Notes Curing conditions: 200~C/8 to 10~,180~C/15' or 170~C/25~
- 2 3 - O . Z . 5088
C 1 Piqmented powder coatinqs
Table 9:
S Example C1 1 2 34" 5 6 7 8 9 10
Formulation
CrosslinkerA2 27.7517.2425.07 21.12 20.33 15.36 15.98 27.58 21.92 16.64
Table 5 Ex 0 (1) (1) (3) (3) (3) (3) (5) (7) (8) (8) D
Polyester B 1 72.25 - 74.93 78.88 - - - 72.42 - - o
Polyester B 2 - - - - 79.67 - - - 78.08 - ~
Polyes~er B 3 - 82.76 - - - 84.6484.02 - - 83.36 ~n
Notes All ~ormulations contain 40% by weight of TiO2 (white pigment) and 0.5% by weight each of leveling agent and benzoin, and also 0.15% by weight of DBTL the OH/NCO I--
ratio is 1 :1; o) OH/NCO = 1 :0.8 ~
Coatings data O
LT 65-8271-89 72-8969-90 67-92 81-9367-85 63-8177-91 67-80
GG 60~ . 89/90 90 89-90 90 89-90 90 89-9190-91 90/91 89/91
CH 0 0 0 0 0 0 0 0 0 0
El ~ 109.6/10> 10~ 10 > 10 ~ 109 7/109.5/10 > 10 9.7/10
Imp lev. 691 2460.8691 2 576 806 4691 2576691 2 576 460 8
Notes Curing conditions: 200~C/8 to 10 180~C/15' or 170'C/25~
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C 2 Transparent powder coatin~s
In accordance with the process described, transparent powder coatings as well were prepared, applied and baked at
between 200 and 170~C.
Table 10:
Example C 2 1 2 3 4 5 6 7 8
Formulation D
CrosslinkerA2 24.9315.26 17.6227.7516.28 27.07 25.07 16.64
Table 3 Ex. ~(6) t6)(10)
Table 4 Ex. 0 - - - (6)(1o) (18) - -
Table 5 Ex. () - - - (3~ (3)
Polyester B 1 75.07 - - 72.25 - 72.93 74.93 - Cl'
Polyester B 3 - 84.7482.38 - 83.72 - ~ 83.36 v~
Notes All formulations contain 0.5% by weight of leveling agent and 0.3% by weight of benzoin and also 0.1 % by weight of DBTL; the O
OH/NCO ratio is 1 :1
Coatings data
LT 63-7159-7064-7863-7066-8064-7558-69 63-71
HK 206 200 199 204 200 197 194 190
CH 0 0 0 0 0 0 0 0
2 0 El > 10~ 10> 10> 10> 10> 10~ 10 > 10
Notes Curing conditions: 200~C/6-8',180~C/12-15' or 170~C/20-25'
