U.S. patent application number 17/040071 was filed with the patent office on 2021-01-28 for aqueous uretdione group-containing compositions and method for producing same.
The applicant listed for this patent is Covestro Deutschland AG, Covestro LLC. Invention is credited to Saskia Beuck, Sebastian Doerr, Heinz-Dietmar Gewiss, Dorota Greszta-Franz, Hans-Josef Laas, Nusret Yuva.
Application Number | 20210024680 17/040071 |
Document ID | / |
Family ID | 1000005134855 |
Filed Date | 2021-01-28 |
United States Patent
Application |
20210024680 |
Kind Code |
A1 |
Greszta-Franz; Dorota ; et
al. |
January 28, 2021 |
AQUEOUS URETDIONE GROUP-CONTAINING COMPOSITIONS AND METHOD FOR
PRODUCING SAME
Abstract
The invention relates to aqueous uretdione group-containing
compositions comprising or consisting of (A) at least one uretdione
group-containing curing agent based on aliphatic, cycloaliphatic,
araliphatic, and/or aromatic polyisocyanates which do not contain
chemically bonded hydrophilating groups; (B) at least one hydroxy
group-containing polyol which contains at least one chemically
bonded carboxylic acid group; (C) optionally solvents; and (D)
optionally auxiliary agents and additives; wherein the quantity
ratio of the components (A) and (B) is measured such that the molar
ratio of the NCO groups of the curing agent (A), said groups being
provided in the form of uretdione, to the NCO reactive groups of
the polyol (B) equals 3.0:0.5 to 0.5:3.0, and A and B are provided
as a physical mixture. The invention additionally relates to a
method for producing a polyurethane layer using the aqueous
uretdione group-containing composition according to the invention,
to the polyurethane layer obtained therefrom, and to a substrate
which is coated with or adhered to the polyurethane layer.
Inventors: |
Greszta-Franz; Dorota;
(Solingen, DE) ; Beuck; Saskia; (Leverkusen,
DE) ; Doerr; Sebastian; (Dusseldorf, DE) ;
Laas; Hans-Josef; (Odenthal, DE) ; Yuva; Nusret;
(Burscheid, DE) ; Gewiss; Heinz-Dietmar;
(Meerbusch, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Covestro Deutschland AG
Covestro LLC |
Leverkusen
Pittsburgh |
PA |
DE
US |
|
|
Family ID: |
1000005134855 |
Appl. No.: |
17/040071 |
Filed: |
March 21, 2019 |
PCT Filed: |
March 21, 2019 |
PCT NO: |
PCT/EP2019/057064 |
371 Date: |
September 22, 2020 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08G 18/4277 20130101;
C08G 18/2063 20130101; C08G 18/2036 20130101; C08G 18/44 20130101;
C08G 18/798 20130101; C09D 175/04 20130101; C09D 175/02 20130101;
C09J 175/04 20130101; C08G 18/48 20130101; C08G 18/4236 20130101;
C08G 18/622 20130101; C08G 18/1858 20130101; C08G 18/027 20130101;
C08K 2201/012 20130101; C08G 18/6229 20130101; C09J 175/02
20130101; C08G 18/2027 20130101; C08K 5/29 20130101; C08G 2190/00
20130101 |
International
Class: |
C08G 18/02 20060101
C08G018/02; C08K 5/29 20060101 C08K005/29; C08G 18/48 20060101
C08G018/48; C08G 18/62 20060101 C08G018/62; C08G 18/44 20060101
C08G018/44; C08G 18/20 20060101 C08G018/20; C08G 18/42 20060101
C08G018/42; C09D 175/04 20060101 C09D175/04; C08G 18/18 20060101
C08G018/18; C08G 18/79 20060101 C08G018/79; C09J 175/04 20060101
C09J175/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 23, 2018 |
EP |
18163620.0 |
Mar 23, 2018 |
EP |
18163621.8 |
Mar 23, 2018 |
EP |
18163625.9 |
Jul 5, 2018 |
EP |
18181876.6 |
Jul 5, 2018 |
EP |
18181877.4 |
Claims
1. An aqueous uretdione group-containing compositions comprising;
(A) at least one uretdione group-containing curing agent based on
aliphatic, cycloaliphatic, araliphatic or aromatic polyisocyanates
that contains no chemically-bonded hydrophilizing groups; (B) at
least one hydroxyl-containing polyol that contains at least one
chemically-bonded carboxylic acid group; (C) optionally, solvents;
and (D) optionally, auxiliaries and additives; wherein the
quantitative ratio of components (A) and (B) is such that the molar
ratio of the NCO groups of the curing agent (A) present as
uretdione to NCO-reactive groups of the polyol (B) is 3.0:0.5 to
0.5:3.0 and wherein A and B are present as a mixture.
2. The composition as claimed in claim 1, wherein the at least one
uretdione group-containing curing agent (A) is obtained by reacting
monomeric isocyanates comprising at least one monomeric isocyanate
selected from the group consisting of tetramethylene diisocyanate,
cyclohexane-1,3-diisocyanate, cyclohexane-1,4-diisocyanate,
pentamethylene diisocyanate, hexamethylene diisocyanate-,
1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane,
dicyclohexylmethane-2,4'-diisocyanate,
dicyclohexylmethane-4,4'-diisocyanate, tetramethylxylylene
diisocyanate, triisocyanatononane, tolylene diisocyanate,
diphenylmethane-2,4'-diisocyanate,
diphenylmethane-4,4'-diisocyanate,
triphenylmethane-4,4'-diisocyanate, naphthylene-1,5-diisocyanate,
and mixtures thereof.
3. The composition as claimed in claim 1, wherein
hydroxyl-containing monomers or polymers are used as starting
materials for the at least one uretdione group-containing curing
agent (A).
4. The composition as claimed in claim 1, wherein the at least one
uretdione group-containing curing agent (A) has a free NCO content
of less than 5% by weight and a content of uretdione groups of 1%
to 18% by weight (calculated as C.sub.2N.sub.2O.sub.2, molecular
weight 84 g/mol).
5. The composition as claimed in claim 1, wherein the aqueous
composition has an acid value of 1 to 100 mg KOH/g.
6. The composition as claimed in claim 1, wherein the at least one
hydroxyl-containing polyol (B) is obtained by reacting hydroxy- or
aminocarboxylic acids comprising at least one carboxylic acid
selected from the group consisting of 2,2-dimethylolacetic acid,
2,2-dimethylolbutyric acid, 2,2-dimethylolpentanoic acid,
dihydroxysuccinic acid, .alpha.,.OMEGA.-diaminovaleric acid, and
mixtures thereof.
7. The composition as claimed in claim 1, wherein the polyol (B)
containing at least one hydroxyl group has an OH content greater
than 1% by weight, calculated as OH groups based on the solids
content, a molecular weight of 17 g/mol, and a number-average
molecular weight Mn of 500 to 20 000 g/mol.
8. The composition as claimed in claim 1, wherein the solvent is
selected from the group consisting of acetone, methyl ethyl ketone,
ethyl acetate, butyl acetate, xylene, solvent naphtha, propylene
glycol mono-n-butyl ether, dipropylene glycol dimethyl ether,
methoxypropyl acetate, dibasic esters, and mixtures thereof.
9. The composition as claimed in claim 1, wherein the auxiliaries
and additives are selected from the group consisting of leveling
agents, light stabilizers, catalysts, fillers, and pigments, and
mixtures thereof.
10. The composition as claimed in claim 1, wherein the sum of the
proportions by weight of (A), (B), and (D) is 30% to 60% by weight
based on the solids content of the total aqueous composition.
11. A process for producing a polyurethane layer comprising the
steps of i) providing an aqueous uretdione group-containing
composition as claimed in claim 1; ii) applying to a substrate the
composition obtained in i) to produce a mixture; iii) drying the
mixture from step ii), and iv) curing the mixture from step iii) by
heating to from 40.degree. C. to 180.degree. C. for up to 180
minutes.
12. The process as claimed in claim 11, wherein the aqueous
uretdione group-containing composition is obtained by mixing the
uretdione group-containing curing agent (A) with the polyol (B)
containing at least one hydroxyl group in the absence of water to
obtain a mixture, and subsequently dispersing the mixture with
water.
13. A polyurethane layer obtained by the process as claimed in
claim 11.
14. A substrate coated or bonded with the polyurethane layer as
claimed in claim 13.
Description
[0001] The present invention relates to aqueous uretdione
group-containing compositions comprising or consisting of [0002]
(A) at least one uretdione group-containing curing agent based on
aliphatic, cycloaliphatic, araliphatic and/or aromatic
polyisocyanates that contains no chemically-bonded hydrophilizing
groups; [0003] (B) at least one hydroxyl-containing polyol that
contains at least one chemically-bonded carboxylic acid group;
[0004] (C) optionally solvents; and [0005] (D) optionally
auxiliaries and additives; [0006] wherein the quantitative ratio of
components (A) and (B) is such that the molar ratio of the NCO
groups of the curing agent (A) present as uretdione to NCO-reactive
groups of the polyol (B) is 3:0.5 to 0.5:3 and wherein A and B are
present as a physical mixture.
[0007] The invention further relates to a process for producing a
polyurethane layer using the aqueous uretdione group-containing
composition of the present invention, to the polyurethane layer
obtained therefrom, and to a substrate that is coated or bonded
with said polyurethane layer.
[0008] Recent years have seen a sharp rise in the profile of
aqueous paints and coating compositions in the wake of increasingly
stringent emissions directives governing the solvents given off
when applying paints. Although for many fields of application there
are now aqueous coating systems available, these systems are often
unable to attain the high quality level of conventional,
solvent-based paints in respect of resistance to solvents and
chemicals or elasticity and mechanical durability. In particular,
there has been no disclosure to date of any polyurethane-based
coating compositions that can be processed from an aqueous phase
and that go far enough towards satisfying the exacting requirements
of the art. This statement applies both to DE 4001783 A1, which
relates to special anionically modified aliphatic polyisocyanates,
and to the systems of DE 2456469 A1, DE 2814815 A1, EP 0012348 A1,
and EP 0424697 A1, which describe aqueous, one-component
baking-enamel binders based on blocked polyisocyanates and organic
polyhydroxy compounds.
[0009] In recent years, further improvements to one-component
baking-enamel binders based on blocked polyisocyanates have been
achieved, as described for example in EP 0576952A.
[0010] The above one-component baking-enamel binders of the prior
art that are based on blocked polyisocyanates have the
disadvantage, even if they are largely solvent-free, that the
blocking agents are released when the enamel binders are baked,
which in turn contributes to emissions.
[0011] There has consequently long been a market demand for
developing aqueous, emission-free one-component baking-enamel
binders. There has been no shortage of attempts at producing such
baking-enamel binders based on uretdione-containing polyisocyanates
that do not give rise to elimination products.
[0012] According to EP 1687354 A1, aqueous uretdione-containing
dispersion coatings can be produced by combining a solid uretdione
compound with a molten water-dispersible resin, salting the
water-dispersible resin if necessary, and dispersing the resin
mixture in water. The molten water-dispersible resin may contain a
functionality that is reactive toward the uretdione compound, or
the coating composition may contain another water-dispersible resin
having a functionality that is reactive toward the uretdione
compound. In the example, an epoxy resin was however used. Epoxy
coatings are generally known to be inferior in most properties to
polyurethane coatings. According to EP 1687354 A1, it is also
necessary to use an additional emulsifier in the production of
these dispersion coatings, which further compromises the coating
properties of the dispersion coatings. In addition, the method of
production described in EP 1687354 A1 is associated with very high
thermal stress on the uretdione groups, which in practice would
most likely lead to loss of the uretdione groups. The dispersions
described in EP 1687354 A1 were moreover applied immediately,
directly after preparation. EP 1687354 A1 provides no information
on the stability of these dispersions.
[0013] U.S. Pat. No. 4,496,684 A described uretdione
group-containing polyurethane oligomers prepared by reacting a
hydroxyl-terminated prepolymer with a dicarboxylic anhydride. This
document does not include any aqueous composition in which the
uretdione group-containing curing agent and the polyol are present
as a physical mixture.
[0014] Further examples of water-dispersible hydrophilic
uretdione-containing polyisocyanates are given in, for example, DE
2538484 A1 and DE 10 2005 036 654 A1. In both documents, a
hydrophilizing group (i.e. a carboxyl group) was incorporated
directly into the uretdione-containing polyisocyanate. Neither DE
2538484 A nor DE 10 2005 036 654 A1 give any information on the
stability of these dispersions. These also differ in that no
physical mixtures of a specific uretdione group-containing curing
agent and a specific polyol are present.
[0015] US 2015232609A1 discloses water-dispersible hydrophilic
uretdione-containing polyisocyanates obtainable by reacting a
prepolymer bearing uretdione groups with an emulsifier containing
an ionogenic group, with the ionogenic group having either a pKa of
>8 or a pKb of >8 in water at room temperature. Although such
uretdione-containing reaction products exhibited an improved
storage stability of 8 weeks at room temperature, this is still
inadequate for practical uses in industry, where it is not uncommon
for transport over long distances to be necessary.
[0016] The above problems were surprisingly solved by using a
physical mixture of the specific curing agent and the specific
polyol of the present invention. In particular, dispersions were
obtained that show increased storage stability compared to known
prior art compositions.
[0017] The present invention relates in particular to: [0018] 1.
Aqueous uretdione group-containing compositions comprising or
consisting of [0019] (A) at least one uretdione group-containing
curing agent based on aliphatic, cycloaliphatic, araliphatic and/or
aromatic polyisocyanates, preferably based on based on aliphatic,
cycloaliphatic and/or araliphatic polyisocyanates, more preferably
based on aliphatic and/or cycloaliphatic polyisocyanates, that
contains no chemically-bonded hydrophilizing groups; [0020] (B) at
least one hydroxyl-containing polyol that contains at least one
chemically-bonded carboxylic acid group; [0021] (C) optionally
solvents; and [0022] (D) optionally auxiliaries and additives;
[0023] wherein the quantitative ratio of components (A) and (B) is
such that the molar ratio of the NCO groups of the curing agent (A)
present as uretdione to NCO-reactive groups of the polyol (B) is
3.0:0.5 to 0.5:3.0, preferably 2.5:1.0 to 1.0:2.5, more preferably
2.0:2.0 to 1.0 to 1.0:2.0, and wherein (A) and (B) are present as a
physical mixture. [0024] 2. Aqueous uretdione group-containing
composition according to aspect 1, characterized in that the at
least one uretdione group-containing curing agent (A) was obtained
by reacting monomeric isocyanates comprising or consisting of at
least one monomeric isocyanate selected from tetramethylene
diisocyanate, cyclohexane-1,3-diisocyanate and
cyclohexane-1,4-diisocyanate, pentamethylene diisocyanate,
hexamethylene diisocyanate (HDI),
1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane
(isophorone diisocyanate IPDI),
dicyclohexylmethane-2,4'-diisocyanate and/or
dicyclohexylmethane-4,4'-diisocyanate, tetramethylxylylene
diisocyanate (TMXDI), triisocyanatononane, tolylene diisocyanate
(TDI), diphenylmethane-2,4'-diisocyanate and/or
diphenylmethane-4,4'-diisocyanate (MDI),
triphenylmethane-4,4'-diisocyanate or naphthylene-1,5-diisocyanate
or mixtures thereof, preferably from isophorone diisocyanate,
dicyclohexylmethane-2,4'-diisocyanate and/or
dicyclohexylmethane-4,4'-diisocyanate, or hexamethylene
diisocyanate. [0025] 3. Aqueous uretdione group-containing
composition according to aspect 1 or 2, characterized in that
[0026] hydroxyl-containing monomers and/or polymers are used as
starting materials for the at least one uretdione group-containing
curing agent (A). [0027] 4. Aqueous uretdione group-containing
composition according to any of the preceding aspects,
characterized in that [0028] the at least one uretdione
group-containing curing agent (A) has a free NCO content of less
than 5% by weight and a content of uretdione groups of 1% to 18% by
weight (calculated as C.sub.2N.sub.2O.sub.2, molecular weight 84
g/mol). [0029] 5. Aqueous uretdione group-containing composition
according to any of the preceding aspects, characterized in that
[0030] the aqueous composition has an acid value of 1 to 100 mg
KOH/g, preferably 2 to 50 mg KOH/g, more preferably 5 to 30 mg
KOH/g, preferably measured in accordance with DIN EN ISO 2114:
2002-06 with acetone and ethanol in a weight ratio of 2:1 as
solvent, and calculated based on the solids content. [0031] 6.
Aqueous uretdione group-containing composition according to any of
the preceding aspects, characterized in that [0032] the at least
one hydroxyl-containing polyol (B) was obtained by reacting
hydroxy- or aminocarboxylic acids comprising or consisting of at
least one carboxylic acid selected from 2,2-dimethylolacetic acid,
2,2-dimethylolbutyric acid, 2,2-dimethylolpentanoic acid,
dihydroxysuccinic acid, .alpha.,.OMEGA.-diaminovaleric acid or
mixtures thereof, preferably from dimethylolpropionic acid or
hydroxypivalic acid. [0033] 7. Aqueous uretdione group-containing
composition according to any of the preceding aspects,
characterized in that [0034] the polyol (B) containing at least one
hydroxyl group has an OH content greater than 1% by weight,
calculated as OH groups based on the solids content, a molecular
weight of 17 g/mol, and a number-average molecular weight Mn of 500
to 20 000 g/mol. [0035] 8. Aqueous uretdione dispersion according
to any of the preceding aspects, characterized in that [0036] the
solvent is selected from acetone, methyl ethyl ketone, ethyl
acetate, butyl acetate, xylene, solvent naphtha, such as the
commercially available Solvesso 100 or Solvesso 150, propylene
glycol mono-n-butyl ether, dipropylene glycol dimethyl ether,
methoxypropyl acetate, dibasic esters or mixtures thereof. [0037]
9. Aqueous uretdione dispersion according to any of the preceding
aspects, characterized in that [0038] the auxiliaries and additives
are selected from the group consisting of leveling agents, for
example polysilicones or acrylates, light stabilizers, for example
sterically hindered amines, catalysts, for example tin(II)
2-ethylhexanoate or dibutyltin dilaurate, fillers, and pigments,
for example titanium dioxide, or mixtures thereof [0039] 10.
Aqueous uretdione group-containing composition according to any of
the preceding aspects, characterized in that [0040] the sum of the
proportions by weight of (A), (B), and (D) is 30% to 60% by weight
based on the solids content of the total aqueous composition.
[0041] 11. A process for producing a polyurethane layer comprising
the steps of [0042] i) providing an aqueous uretdione
group-containing composition according to any of aspects 1 to 10;
[0043] ii) applying to a substrate the mixture obtained in i);
[0044] iii) drying the mixture from step ii), and [0045] iv) curing
the mixture from step iii) by heating to from 40.degree. C. to
180.degree. C. for up to 180 minutes. [0046] 12. The process
according to aspect 11, characterized in that the aqueous uretdione
group-containing composition was obtained by mixing the uretdione
group-containing curing agent (A) with the polyol (B) containing at
least one hydroxyl group in the absence of water and subsequently
dispersing the mixture with water. [0047] 13. A polyurethane layer,
in particular polyurethane film, obtainable by a process according
to aspect 11 or 12. [0048] 14. A substrate that is coated or bonded
with the polyurethane layer according to aspect 13.
[0049] The average molecular weight is according to this invention
defined as the number-average molecular weight Mn, unless
explicitly stated otherwise. The Mn is determined by gel-permeation
chromatography (GPC) at 23.degree. C. in tetrahydrofuran as
solvent. The measurement is carried out as described in DIN
55672-1:2016-03: "Gel permeation chromatography, Part
1--Tetrahydrofuran as eluent" (Security GPC system from PSS Polymer
Service, flow rate 1.0 ml.
[0050] Unless explicitly stated otherwise, % by weight in the
present invention refers to the total weight of the respective
system or the total weight of the respective component. For
example, a copolymer may have a content of a particular monomer
that is expressed in % by weight, in which case the percent by
weight values would be based on the total weight of the
copolymer.
[0051] Unless explicitly stated otherwise, the expression "at least
one" refers to the type of compound and not to individual
molecules. For example, at least one polyol is to be understood as
meaning that at least one type of polyol is present, but is present
in the composition in an indeterminate number of molecules. Hence
it is also possible for two or more types of polyol be present, in
each case in an indeterminate number if the amounts are not
defined.
[0052] In a preferred embodiment, the aqueous uretdione
group-containing composition is substantially free of any other
co-emulsifier (in addition to component (B)). The term
"substantially free of" is according to the present invention
defined as meaning that the composition contains preferably less
than 1% by weight, more preferably less than 0.25% by weight, even
more preferably less than 0.1% by weight, most preferably less than
0.01% by weight or no content at all of the respective compound, in
each case based on the total weight of the aqueous uretdione
group-containing composition.
[0053] The aqueous uretdione group-containing composition of the
present invention is preferably a polyurethane-based
composition.
[0054] Suitable uretdione group-containing polyisocyanates as
starting compounds for component (A) are polyisocyanates that
contain at least one isocyanate group and at least one uretdione
group. These are prepared through the reaction of suitable starting
isocyanates (a1) as described for example in WO 02/92657 A1 or WO
2004/005364 A1. In this reaction, some of the isocyanate groups are
converted into uretdione groups with the aid of a catalyst, for
example a triazolate or 4-dimethylaminopyridine (DMAP). Examples of
isocyanates (a1) from which the uretdione-containing structural
units are constructed are tetramethylene diisocyanate,
cyclohexane-1,3-diisocyanate and cyclohexane-1,4-diisocyanate,
pentamethylene diisocyanate, hexamethylene diisocyanate (HDI),
1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane
(isophorone diisocyanate IPDI),
dicyclohexylmethane-2,4'-diisocyanate and/or
dicyclohexylmethane-4,4'-diisocyanate, tetramethylxylylene
diisocyanate (TMXDI), triisocyanatononane, tolylene diisocyanate
(TDI), diphenylmethane-2,4'-diisocyanate and/or
diphenylmethane-4,4'-diisocyanate (MDI),
triphenylmethane-4,4'-diisocyanate or naphthylene-1,5-diisocyanate,
and any desired mixtures of such isocyanates. Preference is given
to isophorone diisocyanate, dicyclohexylmethane-2,4'-diisocyanate
and/or dicyclohexylmethane-4,4'-diisocyanate or hexamethylene
diisocyanate.
[0055] In addition to the isocyanate groups and uretdione groups,
component (A) may also contain isocyanurate, biuret, allophanate,
urethane and/or urea structures.
[0056] The conversion of these uretdione group-bearing
polyisocyanates into uretdione group-containing curing agents (A)
involves the reaction of the free NCO groups of the abovementioned
polyisocyanates with a polyol component (b1), optionally with the
additional use of the polyol component (b2).
[0057] The polyol component (b1) preferably has a hydroxy group
functionality of >2 and a molecular weight M. of 62 to 500
g/mol, preferably 62 to 400 g/mol, more preferably 62 to 300 g/mol.
The polyol component (b1) preferably contains dihydric to
hexahydric polyol components having a molecular weight Mn of 62 to
500 g/mol, preferably 62 to 400 g/mol, more preferably 62 to 300
g/mol. Examples of preferred polyol components (b1) are
1,4-butanediol and/or 1,3-butanediol, 1,6-hexanediol,
2,2,4-trimethyl-1,3-pentanediol, trimethylolpropane, polyester
polyols and/or polyether polyols having an average molecular weight
M. of less than or equal to 500 g/mol.
[0058] Suitable linear difunctional polyols (b2) are selected from
the group consisting of polyethers, polyesters, polycaprolactone
diols, and/or polycarbonates. The polyol component (b2) preferably
comprises at least one diol containing ester groups and having a
molecular weight Mn of 350 to 4000 g/mol, preferably of 350 to 2000
g/mol, more preferably of 350 to 1000 g/mol, This is the average
molecular weight that is calculable from the hydroxyl value. The
ester diols are generally mixtures in which individual constituents
having a molecular weight below or above these limits may also be
present in minor amounts. These are the polyester diols known per
se that are constructed from diols and dicarboxylic acids.
[0059] Examples of suitable diols are 1,4-dimethylolcyclohexane,
1,4-butanediol or 1,3-butanediol, 1,6-hexanediol, neopentyl glycol,
2,2,4-trimethyl-1,3-pentanediol, trimethylolpropane and
pentaerythritol, and mixtures of such diols. Examples of suitable
dicarboxylic acids are aromatic dicarboxylic acids such as phthalic
acid, isophthalic acid, and terephthalic acid, cycloaliphatic
dicarboxylic acids such as hexahydrophthalic acid,
tetrahydrophthalic acid, endomethylenetetrahydrophthalic acid, and
the anhydrides thereof, and aliphatic dicarboxylic acids, which are
used with preference, for example succinic acid, glutaric acid,
adipic acid, suberic acid, azelaic acid, and sebacic acid or the
anhydrides thereof.
[0060] Polyester diols based on adipic acid, phthalic acid,
isophthalic acid, and tetrahydrophthalic acid are preferably used
as component (b2). Examples of preferred diols used are
1,4-butanediol or 1,3-butanediol, 1,6-hexanediol or
trimethylolpropane, and mixtures thereof.
[0061] Also preferable as component (b2) are polycaprolactone diols
having an average molecular weight of 350 to 4000 g/mol, preferably
of 350 to 2000 g/mol, more preferably of 350 to 1000 g/mol, that
are prepared in a manner known per se starting from a diol or diol
mixture of the type mentioned above, and lactones such as
.beta.-propiolactone, .gamma.-butyrolactone, .gamma.- and
.delta.-valerolactone, .epsilon.-caprolactone, 3,5,5- and
3,3,5-trimethylcaprolactone or any desired mixtures of such
lactones.
[0062] Particular preference is given to polycaprolactone diols
that are prepared by polymerizing .epsilon.-caprolactone.
[0063] (Co)polyethers of ethylene oxide, propylene oxide, and/or
tetrahydrofuran containing less than 30 mol % of ethylene oxide
units may also be used as the linear polyol component (b2).
Preference is given to polyethers having an average molar weight Mn
of 500 to 2000 g/mol, for example polypropylene oxides or
polytetrahydrofuran diols.
[0064] Also suitable as (b2) are hydroxyl-containing
polycarbonates, preferably having an average molar weight Mn of 400
to 4000 g/mol, preferably of 400 to 2000 g/mol, for example
hexanediol polycarbonate and polyester carbonates.
[0065] The polyol component (b2) used in the preparation of the
uretdione group-containing curing agents (A) may also take the form
of diols containing low-molecular-weight ester groups and having an
average molecular weight, calculable from the functionality and
hydroxyl value, of 134 to 349 g/mol, preferably 176 to 349 g/mol.
Examples of these include the diols containing ester groups that
are known per se, or mixtures of such diols, as can be prepared for
example by reacting alcohols with substoichiometric amounts of
dicarboxylic acids, corresponding dicarboxylic anhydrides,
corresponding dicarboxylic esters of lower alcohols or lactones.
Examples of suitable acids are succinic acid, adipic acid, sebacic
acid, phthalic acid, isophthalic acid, phthalic anhydride,
tetrahydrophthalic acid, maleic acid, maleic anhydride, dimethyl
terephthalate, and bisglycol terephthalate. Examples of suitable
lactones for preparing said ester diols are .beta.-propiolactone,
.gamma.-butyrolactone, .gamma.- and .delta.-valerolactone,
.epsilon.-caprolactone, 3,5,5- and 3,3,5-trimethylcaprolactone or
any desired mixtures of such lactones.
[0066] Amino-functional compounds may also be used in the
preparation of the uretdione group-containing curing agents (A).
Examples of suitable low-molecular-weight amino-functional
compounds are aliphatic and cycloaliphatic amines and aminoalcohols
having primary and/or secondary amino groups, for example
cyclohexylamine, 2-methyl-1,5-pentanediamine, diethanolamine,
monoethanolamine, propylamine, butylamine, dibutylamine,
hexylamine, monoisopropanolamine, diisopropanolamine,
ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane,
isophoronediamine, diethylenetriamine, ethanolamine,
aminoethylethanolamine, diaminocyclohexane, hexamethylenediamine,
methyliminobispropylamine, iminobispropylamine,
bis(aminopropyl)piperazine, aminoethylpiperazine,
1,2-diaminocyclohexane, triethylenetetramine,
tetraethylenepentamine, bis(4-aminocyclohexyl)methane,
bis(4-amino-3-methylcyclohexyl)methane,
bis(4-amino-3,5-dimethylcyclohexyl)methane,
bis(4-amino-2,3,5-trimethylcyclohexyl)methane,
1,1-bis(4-aminocyclohexyl)propane,
2,2-bis(4-aminocyclohexyl)propane, 1,1-bis (4-aminocyclohexyl)
ethane, 1,1-bis(4-aminocyclohexyl)butane, 2,2-bis
(4-aminocyclohexyl)butane, 1,1-bis(4-amino-3-methylcyclohexyl)
ethane, 2,2-bis (4-amino-3-methylcyclohexyl)propane, 1,1-bis
(4-amino-3,5-dimethylcyclohexyl)ethane, 2,2-bis
(4-amino-3,5-dimethylcyclohexyl)propane, 2,2-bis
(4-amino-3,5-dimethylcyclohexyl)butane,
2,4-diaminodicyclohexylmethane,
4-aminocyclohexyl-4-amino-3-methylcyclohexylmethane,
4-amino-3,5-dimethylcyclohexyl-4-amino-3-methylcyclohexylmethane,
and
2-(4-aminocyclohexyl)-2-(4-amino-3-methylcyclohexyl)methane.
[0067] Solvents may optionally be used in the preparation of the
uretdione group-containing curing agents (A). Suitable as solvent
for the uretdione group-containing curing agents (A) are all liquid
substances that do not react with other constituents, for example
acetone, methyl ethyl ketone, ethyl acetate, butyl acetate, xylene,
solvent naphtha, such as the commercially available Solvesso 100
and Solvesso 150, propylene glycol mono-n-butyl ether, dipropylene
glycol dimethyl ether, methoxypropyl acetate, dibasic esters or
mixtures thereof.
[0068] The uretdione group-containing curing agents (A) are
substantially free of ionic or nonionic, chemically bonded
hydrophilizing groups. Tonically hydrophilizing groups are
understood by those skilled in the art as meaning groups having the
capability of forming anions or cations. Groups capable of forming
anions or cations are ones that can be converted into an anionic or
cationic group through chemical reaction, in particular through
neutralization.
[0069] The uretdione group-containing curing agents (A) are
preferably free of carboxyl group-containing polyols or diols
capable of anion formation, for example dihydroxycarboxylic acids
such as .alpha.,.alpha.-dialkylolalkanoic acids, in particular
.alpha.,.alpha.-dimethylolalkanoic acids such as
2,2-dimethylolacetic acid, 2,2-dimethylolpropionic acid,
2,2-dimethylolbutyric acid, 2,2-dimethylolpentanoic acid,
dihydroxysuccinic acid, or polyhydroxy acids such as gluconic acid.
In addition, the uretdione group-containing curing agents (A) are
preferably free of compounds containing amino groups and capable of
anion formation such as .alpha.,.OMEGA.-diaminovaleric acid or
2,4-diaminotoluenesulfonic acid. The uretdione group-containing
curing agents (A) are also preferably free of sulfonic acid groups
capable of anion formation.
[0070] The uretdione group-containing curing agents (A) are
additionally preferably free of compounds capable of cation
formation from the group consisting of tertiary amino or ammonium
compounds, for example tris(hydroxyalkyl)amines,
N,N'-bis(hydroxyalkyl)alkylamines, N-hydroxyalkyldialkylamines,
trisaminoalkylamines, N,N'-bis(aminoalkyl)alkylamines,
N-aminoalkyldialkylamines, and mixtures thereof.
[0071] The uretdione group-containing curing agents (A) are further
preferably free of nonionically hydrophilizing compounds such as
polyalkylene oxide polyether alcohols or polyalkylene oxide
polyether amines. In particular, the uretdione group-containing
curing agents (A) are preferably free of polyethylene oxide
polyethers or mixed polyalkylene oxide polyethers in which 30 mol %
or more of the alkylene oxide units consist of ethylene oxide
units.
[0072] Preferred uretdione group-containing curing agents (A) have
a free NCO content of less than 5% by weight and a content of
uretdione groups of 1% to 18% by weight (calculated as
C.sub.2N.sub.2O.sub.2, molecular weight 84 g/mol). In addition to
the uretdione groups, the curing agents (A) may also contain
isocyanurate, biuret, allophanate, urethane, and/or urea
structures.
[0073] The composition also comprises at least one
hydroxyl-containing polyol that contains at least one
chemically-bonded carboxylic acid group (component (B)).
[0074] Suitable polyols (B) may be selected from polyester polyols,
polyether polyols, polyurethane ether polyols, polyurethane ester
polyols, polycaprolactone polyols, polyether ester polyols,
polycarbonate polyols, C.sub.2-10 hydrocarbon containing at least
two hydroxy groups or mixtures thereof, provided such polyols have
at least one chemically bonded carboxylic acid group. Preference is
given to suitable polyols (B) from the group consisting of
polyurethane ether polyols, polyurethane ester polyols,
polycaprolactone polyols or polycarbonate polyols, with particular
preference given to polyurethane ester polyols (B) prepared from 5%
to 80% by weight, preferably 10% to 60% by weight, of isocyanates
(a1),
10% to 80% by weight, preferably 40% to 70% by weight, of polyols
(b2) and/or amino-functional compounds having an average molar
weight Mn of at least 400 g/mol; 2% to 15% by weight, preferably 3%
to 10% by weight, of a starting component (b3) having at least one
chemically bonded carboxylic acid group, 0% to 20% by weight,
preferably 1-10%, of polyols (b1), 0% to 20% by weight of compounds
that are monofunctional or contain active hydrogen of varying
reactivity. and 0% to 20% by weight of compounds that are different
than (b1), (b2), and (b3) and contain at least two groups reactive
toward NCO groups.
[0075] Suitable as the starting component (b3) for the polyols (B)
having at least one chemically bonded carboxylic acid group are
polyols, preferably diols, containing at least one carboxylic acid
group, generally 1 to 3 carboxylic acid groups, per molecule.
Examples include dihydroxycarboxylic acids such as
.alpha.,.alpha.-dialkylolalkanoic acids, in particular
.alpha.,.alpha.-dimethylolalkanoic acids such as
2,2-dimethylolacetic acid, 2,2-dimethylolpropionic acid,
2,2-dimethylolbutyric acid, 2,2-dimethylolpentanoic acid,
dihydroxysuccinic acid, and also polyhydroxy acids such as gluconic
acid, or aminocarboxylic acids such as
.alpha.,.OMEGA.-diaminovaleric acid, and 2,4-diaminotoluenesulfonic
acid. Mixtures of the compounds described above may also be
used.
[0076] Particular preference is given to 2,2-dimethylolpropionic
acid as the starting component (b3) for the polyols (B) having at
least one chemically bonded carboxylic acid group. Alternatively,
monohydroxy-functional compounds having at least one carboxylic
acid group, such as hydroxypivalic acid or hydroxydecanoic acid,
may also be used.
[0077] Suitable polyols (B) are polyols preferably having an OH
content greater than 1% by weight (calculated as OH groups based on
the solids content, molecular weight 17 g/mol) and preferably
having a number-average molecular weight Mn of 500 to 20 000 g/mol,
preferably of 500 to 10 000 g/mol, more preferably of 500 to 5000
g/mol.
[0078] The polyurethane resin used according to the invention is
preferably produced in such a way that a non-aqueous resin
precursor of the polyol (B) is mixed homogeneously in a non-aqueous
system with at least one uretdione group-containing curing agent
(A) based on aliphatic, (cyclo)aliphatic, araliphatic and/or
aromatic polyisocyanates that contains no chemically bonded
hydrophilizing groups. After this, the carboxylic acid groups
present in the polyol (B) are neutralized with suitable
neutralizing agents preferably to at least 50%, more preferably 80%
to 120%, particularly preferably 95 to 105%, and then dispersed
with deionized water. The neutralization can take place before,
during or after the dispersion step. Neutralization before the
addition of water is however preferred.
[0079] Examples of suitable neutralizing agents are triethylamine,
dimethylaminoethanol, dimethylcyclohexylamine, triethanolamine,
methyldiethanolamine, diisopropanolamine, ethyldiisopropylamine,
diisopropylcyclohexylamine, N-methylmorpholine,
2-amino-2-methyl-1-propanol, ammonia or other customary
neutralizing agents or neutralizing mixtures thereof. Preference is
given to tertiary amines such as triethylamine and
diisopropylhexylamine, and particular preference to
dimethylethanolamine
[0080] In accordance with the present invention, the neutralizing
agents are to be included in the group of auxiliaries and additives
(D).
[0081] Suitable as solvents under (C) are all liquid substances
that do not react with other constituents. Preference is given to
acetone, methyl ethyl ketone, ethyl acetate, butyl acetate, xylene,
solvent naphtha, such as the commercially available Solvesso 100
and Solvesso 150, propylene glycol mono-n-butyl ether, dipropylene
glycol dimethyl ether, methoxypropyl acetate, dibasic esters or
mixtures thereof. The solvent used may then optionally be removed
by distillation.
[0082] In accordance with the invention, additives (D) that are
customary in coatings and adhesives technology, for example
leveling agents such as polysilicones or acrylates, light
stabilizers such as sterically hindered amines, catalysts, for
example tin(II) 2-ethylhexyloctoate or dibutyltin dilaurate, or
other auxiliaries such those described in EP 0 669 353, may be
present in a total amount of preferably 0.05% to 5% by weight.
Fillers and pigments such as titanium dioxide may be added to the
aqueous composition in an amount of up to 50% by weight.
[0083] In a preferred embodiment, the aqueous uretdione
group-containing composition contains or consists of
10-50% by weight, preferably 20-40% by weight, of A) based on the
sum A+B 10-80% by weight, preferably 40-70% by weight, of B) based
on the sum A+B 0% to 20% by weight, preferably 1% to 15% by weight,
of C) based on the sum of A+B+D 0-70% by weight, preferably 2-50%
by weight, of D) based on A+B+D.
EXAMPLES
Raw Materials Used:
[0084] Polyester 1: an aliphatic polyester prepared from 1419 g of
trimethylolpropane, 4773 g of neopentyl glycol, 3093 g of adipic
acid, 4101 g of isophthalic acid, and 267 g of 1,2-propylene
glycol, having an acid value of <3 mg KOH/g and an OH value of
181 mg KOH/g.
Analytical Methods Used:
[0085] All viscosity measurements were carried out using a Physica
MCR 51 rheometer from Anton Paar Germany GmbH (DE) in accordance
with DIN EN ISO 3219:1994-10.
[0086] NCO contents were determined titrimetrically in accordance
with DIN EN ISO 11909:2007-05.
[0087] OH values were determined titrimetrically in accordance with
DIN EN ISO 4629-2:2015-02.
[0088] Acid values were determined titrimetrically in accordance
with DIN EN ISO 2114:2002-06.
[0089] Solids contents were determined in a circulating-air oven in
accordance with DIN EN ISO 3251:2008-06, method B.
[0090] Mean particle sizes (MPS) were determined using a Zetasizer
Nano from Malvern (DE) in accordance with DIN ISO
13321:2004-10.
[0091] pH determinations were carried out using a pH meter in
accordance with DIN ISO 976:2008-07 in a 1:4 dilution with
distilled water.
[0092] Residual monomer contents were measured in accordance with
DIN EN ISO 10283 by gas chromatography with an internal
standard.
[0093] Pendulum hardness was measured on a standardized coil test
plate (coil coating black--CS 200570, from Heinz Zanders
Priif-Blech-Logistik) in accordance with DIN EN ISO 1522:2007-04
using a Konig pendulum.
[0094] Chemical resistance was measured on a standardized coil test
plate (coil coating black--CS 200570, from Heinz Zanders
Priif-Blech-Logistik). A cotton pad soaked in the test substance
(xylene or water) was laid on the coating surface and covered with
a watch glass. After the specified contact time, the cotton pad
soaked in test substance was removed and the contact site dried off
and immediately examined. Softening and discoloration of the
coating surface were assessed. The assessment was made in
accordance with DIN EN ISO 4628-1 as follows:
0 no, i.e. no noticeable damage 1 very few areas of damage, i.e.
small, just about significant number 2 a few areas of damage, i.e.
small, but significant number 3 moderate number of areas of damage
4 considerable number of areas of damage 5 very many areas of
damage
[0095] Unless indicated otherwise, all percentages refer to
percentages by weight.
Preparation of a Uretdione Group-Containing Crosslinker
(Crosslinker 1, Preparation Example)
[0096] 1000 g (4.50 mol) of isophorone diisocyanate (IPDI) was
successively mixed at room temperature under dry nitrogen, and with
stirring, with 10 g (1%) of triisodecyl phosphite and 20 g (2%) of
4-dimethylaminopyridine (DMAP) as catalyst. After 20 h, the
reaction mixture, which had an NCO content of 28.7%, corresponding
to a degree of oligomerization of 21.8%, was freed of volatiles,
without prior addition of a catalyst poison, with the aid of a
thin-film evaporator at a temperature of 160.degree. C. and a
pressure of 0.3 mbar. This yielded a light yellow uretdione
polyisocyanate having a free NCO group content of 17.0%, a
calculated content of uretdione groups of 20.8%, a monomeric IPDI
content of 0.4%, and a viscosity of more than 200 000 mPas.
[0097] 337 g of 1,4-butanediol, 108 of 2-ethylhexanol, and 569 g of
.epsilon.-caprolactone were mixed at room temperature under dry
nitrogen, 0.3 g of tin(II) octoate was added, and the mixture was
stirred at 160.degree. C. for 5 h and then cooled to room
temperature. To this mixture was then added, over a period of 30
min, 1850 g of the above-described uretdione group-containing
polyisocyanate based on IPDI, which was warmed to 80.degree. C. The
reaction mixture was stirred at a temperature of max. 100.degree.
C. until the NCO content of the reaction mixture had fallen after 7
to 8 h to a value of 0.8%. The reaction mixture was solidified by
pouring it onto a metal sheet, comminuted, and then dissolved in
acetone to give a solution with a solids content of 70% by
weight.
Examples 1-3 (Inventive)
Example 1
TABLE-US-00001 [0098] TABLE 1 Weight (g) Component 1: POLYESTER 1
875 DIMETHYLOLPROPIONIC ACID 55 TIN(II) 2-ETHYLHEXANOATE 1.4
ACETONE 471 Component 2: HEXAMETHYLENE DIISOCYANATE 169 Component
3: CROSSLINKER 1 (70% in ACETONE) 458 Component 4:
DIMETHYLETHANOLAMINE 36 Component 5: DIST. WATER 1384
[0099] Component 1 from table 1 was weighed into a stirring
apparatus under nitrogen and homogenized for 1 h at 60.degree. C.
Component 2 was then metered in at 55.degree. C. such that the
exothermicity caused the mixture to boil under reflux. The reaction
mixture was kept under reflux until the NCO content had fallen
below 0.05%. The reaction mixture was then cooled to 50.degree. C.
and component 3 added and stirred in for 1 h at 50.degree. C.
Component 4 was then added and stirring continued for 30 min.
Finally, component 5 was stirred in over a period of 15 min and the
acetone was distilled off under reduced pressure.
[0100] This yielded a dispersion with the following properties:
TABLE-US-00002 Solids content 49.8% by weight Acid value (100%) 20
mg KOH/g OH content (100%, calculated) 1.9% by weight Mean particle
size 143 nm Viscosity 640 mPas pH 7.8
[0101] The dispersion remained stable for 14 months at 23.degree.
C.
Example 2
[0102] Example 2 was prepared in the same way as example 1, except
that 718 g of the crosslinker 1 solution and 38 g of
dimethylethanolamine were used. The dispersion obtained has the
following properties:
TABLE-US-00003 Solids content 42.6% by weight Acid value (100%) 18
mg KOH/g OH content (100%, calculated) 1.7% by weight Mean particle
size 180 nm Viscosity 850 mPas pH 8.0
[0103] The dispersion remained stable for 14 months at 23.degree.
C.
Example 3
[0104] Example 3 was prepared in the same way as example 1, except
that the amounts shown below in table 2 were used.
TABLE-US-00004 TABLE 2 Weight (g) Component 1: POLYESTER 1 759
DIMETHYLOLPROPIONIC ACID 60 TIN(II) 2-ETHYLHEXANOATE 1.3 ACETONE
667 Component 2: HEXAMETHYLENE DIISOCYANATE 181 Component 3:
CROSSLINKER 1 (70% in ACETONE) 1043 Component 4:
DIMETHYLETHANOLAMINE 42 Component 5: DIST. WATER 1690
[0105] The dispersion obtained has the following properties:
TABLE-US-00005 Solids content 40.0% by weight Acid value (100%) 17
mg KOH/g OH content (100%, calculated) 1.2% by weight Mean particle
size 261 nm Viscosity 320 mPas pH 7.6
[0106] The dispersion remained stable for 10 months at 23.degree.
C.
Example 4 (Comparative)
[0107] 1000 g (4.50 mol) of isophorone diisocyanate (IPDI) was
successively mixed at room temperature under dry nitrogen, and with
stirring, with 10 g (1%) of triisodecyl phosphite and 20 g (2%) of
4-dimethylaminopyridine (DMAP) as catalyst. After 20 h, the
reaction mixture, which had an NCO content of 28.7%, corresponding
to a degree of oligomerization of 21.8%, was freed of volatiles,
without prior addition of a catalyst poison, with the aid of a
thin-film evaporator at a temperature of 160.degree. C. and a
pressure of 0.3 mbar.
[0108] A light yellow uretdione polyisocyanate having a free NCO
group content of 17.0% and a viscosity of more than 200 000 mPas
was obtained.
[0109] 219 g of the above-described uretdione group-containing
polyisocyanate, based on IPDI and having a free isocyanate group
content of 17.0% and a calculated uretdione group content of 20.8%,
was under dry nitrogen to 80.degree. C. was weighed into a stirring
apparatus under nitrogen and dissolved in 849 g of acetone at room
temperature. 22.9 g of dimethylolpropionic acid and 2.11 g of
tin(II) 2-ethylhexanoate were then metered into the homogeneous
solution such that the exothermicity caused it to boil under
reflux. The reaction mixture was kept under reflux until an NCO
content of 2.2% was reached. 265.9 g of polyester 1 was then added
and the reaction mixture was stirred under reflux until the NCO
content of the reaction mixture had fallen to a value below 0.1%.
cooled to 50.degree. C. After cooling to 23.degree. C., 16.8 g of
dimethylethanolamine was added to the reaction mixture and stirring
was continued for 30 min. Finally, 1451 g of distilled water was
stirred in over a period of 15 min and the acetone was distilled
off under reduced pressure. This yielded a dispersion with the
following properties:
TABLE-US-00006 Solids content 37.62% by weight Mean particle size
91 nm Viscosity 30 mPas pH 8.0
[0110] After 6 months at 23.degree. C. this dispersion had
developed sediment and after 6 days of storage at 40.degree. C. it
had gelled completely.
Tests of Coating Properties
Examples 5-7 (Inventive)
[0111] Clear coatings were produced from the following compositions
(all weights are in g):
TABLE-US-00007 TABLE 3 Example 5 6 7 Composition from example 1
10.00 Composition from example 2 10.00 Composition from example 3
10.00
[0112] The dispersions were mixed in a SpeedMixer at 2000 rpm for 1
minute and then applied to a metal coil test plate in a layer
thickness of 180 .mu.m (wet) using a coating blade. The plates with
the applied wet coatings were flashed off for 5 min at room
temperature and then baked for 30 min at 180.degree. C. and stored
for 4 days at room temperature. The performance of the stored films
was assessed (table 4).
TABLE-US-00008 TABLE 4 Example 5 6 7 Appearance of the coating
satisfactory satisfactory satisfactory (visual examination) Film
thickness (dry, .mu.) 50 60 50 Pendulum hardness (s) 95 145 200
Resistance to xylene 3 3 3 (5 minutes) Deionized water (1 hour) 1 1
0
[0113] As can be seen from table 4, the uretdione-containing
dispersions of the invention afford hard and resistant
coatings.
* * * * *