U.S. patent application number 17/040068 was filed with the patent office on 2021-01-21 for aqueous uretdione group-containing compositions and method for producing same.
The applicant listed for this patent is Covestro Intellectual Property GmbH & Co. KG, Covestro LLC. Invention is credited to Saskia Beuck, Heinz-Dietmar Gewiss, Dorota Greszta-Franz, Hans-Josef Laas, Nusret Yuva.
Application Number | 20210017323 17/040068 |
Document ID | / |
Family ID | 1000005134854 |
Filed Date | 2021-01-21 |
United States Patent
Application |
20210017323 |
Kind Code |
A1 |
Greszta-Franz; Dorota ; et
al. |
January 21, 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,
aliphatic and/or aromatic polyisocyanates which do not contain
chemically bonded hydrophilating groups; (B) at least one
polyacrylate copolymer; (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
polyacrylate copolymer (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) ; Laas; Hans-Josef; (Odenthal, DE) ; Yuva;
Nusret; (Burscheid, DE) ; Gewiss; Heinz-Dietmar;
(Meerbusch, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Covestro Intellectual Property GmbH & Co. KG
Covestro LLC |
Leverkusen
Pittsburgh |
PA |
DE
US |
|
|
Family ID: |
1000005134854 |
Appl. No.: |
17/040068 |
Filed: |
March 21, 2019 |
PCT Filed: |
March 21, 2019 |
PCT NO: |
PCT/EP2019/057069 |
371 Date: |
September 22, 2020 |
Related U.S. Patent Documents
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Application
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15933553 |
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10633477 |
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17040068 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08G 18/622 20130101;
C08G 18/2063 20130101; C08G 18/4277 20130101; C08G 2190/00
20130101; C09D 175/02 20130101; C08G 18/44 20130101; C08G 18/798
20130101; C09D 175/04 20130101; C09J 175/04 20130101; C08G 18/48
20130101; C08G 18/4236 20130101; C08K 2201/012 20130101; C08G
18/027 20130101; C08G 18/6229 20130101; C08G 18/1858 20130101; C09J
175/02 20130101; C08G 18/2027 20130101; C08K 5/29 20130101; C08G
18/2036 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
one or more of aliphatic, cycloaliphatic, araliphatic, and aromatic
polyisocyanates that contains no chemically-bonded hydrophilizing
groups; (B) at least one polyacrylate copolymer; (C) optionally,
solvents; and (D) optionally, auxiliaries and additives; wherein
the quantitative ratio of the at least one uretdione
group-containing curing agent (A) and the at least one polyacrylate
copolymer (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
polyacrylate copolymer (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) was obtained by
reacting a monomeric isocyanate comprising at least one monomeric
isocyanate selected from the group consisting of tetramethylene
diisocyanate, cyclohexane-1,3-diisocyanate and
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, toluene 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
polyacrylate copolymer is obtained by reacting a mixture of
free-radically polymerizable monomers (M), comprising (M1)
hydroxyl- and carboxyl-free (meth)acrylic esters having C1 to C12
hydrocarbon radicals in the alcohol moiety; (M2)
hydroxyl-functional, free-radically polymerizable monomers; (M3)
carboxyl-functional, free-radically polymerizable monomers; (M4)
optionally, vinyl esters of aliphatic carboxylic acids; (M5)
optionally, at least one cycloaliphatic ester of (meth)acrylic acid
and/or vinylaromatics.
7. The composition as claimed in claim 1, wherein the at least one
polyacrylate copolymer (B) has an OH content greater than 1% by
weight--calculated as OH groups based on the solids content,
molecular weight 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 or
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 was obtained by mixing the
uretdione group-containing curing agent (A) with the at least one
polyacrylate copolymer (B) in the absence of water to form a
mixture, and subsequently dispersing the mixture with water.
13. A polyurethane layer obtained by a 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 polyacrylate copolymer; [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
polyacrylate copolymer (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 0576952 A.
[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] 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.
[0014] The above problems were surprisingly solved by using a
physical mixture of the specific curing agent and the polyacrylate
copolymer of the present invention. In particular, dispersions were
obtained that show increased storage stability compared to known
prior art compositions.
[0015] The present invention relates in particular to: [0016] 1.
Aqueous uretdione group-containing compositions comprising or
consisting of [0017] (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; [0018] (B) at least one polyacrylate copolymer; [0019] (C)
optionally solvents; and [0020] (D) optionally auxiliaries and
additives; [0021] 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
polyacrylate copolymer (B) is 3.0:0.5 to 0.5:3.0, preferably
2.5:1.0 to 1.0:2.5, more preferably 2.0:1.0 to 1.0:2.0, and wherein
(A) and (B) are present as a physical mixture. [0022] 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. [0023] 3. Aqueous uretdione group-containing
composition according to aspect 1 or 2, characterized in that
hydroxyl-containing monomers and/or polymers are used as starting
materials for the at least one uretdione group-containing curing
agent (A). [0024] 4. Aqueous uretdione group-containing composition
according to any of the preceding aspects, characterized in that
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. [0025] 5. Aqueous
uretdione group-containing composition according to any of the
preceding aspects, characterized in that 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. [0026] 6. Aqueous uretdione group-containing
composition according to any of the preceding aspects,
characterized in that [0027] the at least one polyacrylate
copolymer (B) is obtained by reacting a mixture of free-radically
polymerizable monomers (M), comprising or consisting of [0028] (M1)
hydroxyl- and carboxyl-free (meth)acrylic esters having C1 to C12
hydrocarbon radicals in the alcohol moiety; [0029] (M2)
hydroxyl-functional, free-radically polymerizable monomers; [0030]
(M3) carboxyl-functional, free-radically polymerizable monomers;
[0031] (M4) optionally vinyl esters of aliphatic carboxylic acids;
[0032] (M5) optionally at least one cycloaliphatic ester of
(meth)acrylic acid and/or vinylaromatics. [0033] 7. Aqueous
uretdione group-containing composition according to any of the
preceding aspects, characterized in that [0034] the polyacrylate
copolymer (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, molecular weight 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 at least one
polyacrylate copolymer (B) 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] Unless explicitly stated otherwise, molecular weights in the
present invention are determined by GPC (gel-permeation
chromatography) using polystyrene standards. The average molecular
weight is according to this invention defined as the number-average
molecular weight Mn. The Mn is determined at 23.degree. C. in
tetrahydrofuran as solvent. The measurement is carried out as
described in DIN 55672-1:2007-08: "Gel permeation chromatography,
Part 1--Tetrahydrofuran as eluent" using a Security GPC system from
PSS Polymer Service, flow rate 0.6 ml/min.
[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 copolymer is to be understood
as meaning that at least one type of copolymer 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 copolymer to 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 (al) 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 under catalysts, for example with
triazolates or 4-dimethylaminopyridine (DMAP) as catalysts.
Examples of isocyanates (al) 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 .gtoreq.2 and a molecular weight M.sub.n 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.sub.n 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, 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 by way of example, and lactones
such as .beta.-propiolactone, .gamma.-butyrolactone, .gamma.- and
.delta.-valerolactone, .epsilon.-caprolactone, 3,5,5- and
3,3,5-trimethylcaprolactone, for example, or any desired mixtures
of such lactones. Particular preference is given to such
polycaprolactone diols that are prepared by polymerizing
.epsilon.-caprolactone.
[0062] (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.
[0063] 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.
[0064] 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.
[0065] 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 amino
alcohols containing 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-aminocyclohexyppropane,
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-dimethylcyclohexyppropane,
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.
[0066] 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.
[0067] The uretdione group-containing curing agents (A) are
substantially free of ionic or nonionic, chemically bonded
hydrophilizing groups. Ionically 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 those that can be converted into an anionic
or cationic group through chemical reaction, in particular through
neutralization.
[0068] 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.
[0069] 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.
[0070] The uretdione group-containing curing agents (A) are further
preferably free of nonionically hydrophilizing compounds such as
for example 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.
[0071] 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.
[0072] The composition also comprises at least one polyacrylate
copolymer (component (B)). In accordance with the present
invention, the term "polyacrylate copolymer" encompasses both
polyacrylate copolymers and poly(meth)acrylate copolymers.
[0073] Suitable polyacrylate copolymers may be obtained, for
example, by the synthesis of the following mixture of
free-radically polymerizable monomers (M): [0074] (M1) hydroxyl-
and carboxyl-free (meth)acrylic esters having C1 to C12 hydrocarbon
radicals in the alcohol moiety; [0075] (M2) hydroxyl-functional,
free-radically polymerizable monomers; [0076] (M3)
carboxyl-functional, free-radically polymerizable monomers; [0077]
(M4) optionally vinyl esters of aliphatic carboxylic acids; [0078]
(M5) optionally at least one cycloaliphatic ester of (meth)acrylic
acid and/or vinylaromatics.
[0079] The mixture may further comprise polyols (PO) selected from
the group consisting of polyester polyols and/or polycarbonate
polyols, the polyols having an average hydroxyl group functionality
of at least two.
[0080] The polyacrylate dispersions of the invention can have high
hydroxyl group contents, which means that--without being bound to a
particular theory--a higher degree of crosslinking and thus higher
hardness can be achieved in the resulting coatings.
[0081] In the context of the present invention, acrylic acid or
methacrylic acid are also referred to as (meth)acrylic acid.
[0082] Acrylates and methacrylates having 1 to 18 carbon atoms in
the alcohol component of the ester group are used as monomers (M1)
free of hydroxyl and carboxyl groups. The alcohol moiety is
preferably aliphatic and may be linear or branched.
[0083] Examples of suitable monomers for component (M1) are methyl,
ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, the
isomeric pentyl, hexyl, 2-ethylhexyl, octyl, and dodecyl
(meth)acrylates. Preferred monomers (M1) are methyl, n-butyl,
isobutyl, tert-butyl (meth)acrylate and also 2-ethylhexyl acrylate
and styrene.
[0084] Suitable hydroxy-functional monomers (M2) are ethylenically
unsaturated, hydroxyl-containing monomers such as hydroxyalkyl
esters of unsaturated carboxylic acids, preferably hydroxyalkyl
(meth)acrylates having 2 to 12, preferably 2 to 6, carbon atoms in
the hydroxyalkyl radical. Examples of particularly preferred
compounds are 2-hydroxyethyl (meth)acrylate, the isomeric
hydroxypropyl (meth)acrylates, 2-, 3-, and 4-hydroxybutyl
(meth)acrylates, and the isomeric hydroxyhexyl (meth)acrylates.
Preference is given to 4-hydroxybutyl acrylate (butanediol
monoacrylate) and hydroxyethyl methacrylate.
[0085] Suitable carboxyl-functional free-radically polymerizable
monomers (M3) are olefinically unsaturated monomers that contain
carboxylic acid or carboxylic anhydride groups, such as acrylic
acid, methacrylic acid, beta-carboxyethyl acrylate, crotonic acid,
fumaric acid, maleic anhydride, itaconic acid or monoalkyl esters
of dibasic acids or anhydrides, for example maleic acid monoalkyl
esters. Preference is given to acrylic acid and/or methacrylic
acid.
[0086] Suitable vinyl esters of aliphatic carboxylic acids (M4) may
be included. Examples of such monomers are the esterification
products of vinyl alcohol with linear or branched, aliphatic
carboxylic acids such as vinyl acetate, vinyl propionate, vinyl
butyrate, vinyl 2-ethylhexanoate, vinyl octanoate, vinyl decanoate,
vinyl neodecanoate, vinyl dodecanoate (vinyl laurate) or vinyl
stearate.
[0087] Examples of suitable monomers (M5) are cyclohexyl
(meth)acrylate, cyclohexyl (meth)acrylates having alkyl ring
substituents, 4-tert-butylcyclohexyl (meth)acrylate, norbornyl
(meth)acrylate, and isobornyl (meth)acrylate, with preference given
to isobornyl acrylate and/or isobornyl methacrylate, and particular
preference to isobornyl methacrylate. It is also possible to use
mixtures comprising isobornyl acrylate and isobornyl methacrylate
and other monomers (M5). Particularly suitable vinyl aromatics are
styrene, optionally substituted styrenes, and vinyltoluenes.
Monomers (M5) other than isobornyl acrylate and isobornyl
methacrylate may optionally be used in amounts of less than 10% by
weight based on the total weight of (M1) to (M5).
[0088] Further monomers (M6) such as acetoacetoxyethyl
methacrylate, acrylamide, acrylonitrile, vinyl ether,
methacrylonitrile or vinyl acetates may optionally also be
included. In addition, it is possible to use proportions of
monofunctional polyalkylene oxides having molecular weights of 200
to 3000 g/mol, preferably 350 to 1000 g/mol, or esterified
(meth)acrylic acid, that are suitable as nonionic, hydrophilic
groups. Suitable alkylene oxides include preferably ethylene oxide
or mixtures of ethylene oxide and propylene oxide. However, it is
preferable when hydrophilization of the copolymers is by means of
ionic groups, that is to say monomers (M3).
[0089] The proportions of monomers (M1) to (M6) may be chosen such
that the polyacrylate copolymer has an OH value (DIN EN ISO
4629-1:2016-12) of 50 to 400 mg KOH/g, preferably of 100 to 300 mg
KOH/g solids. In the case of the polyester polyols and/or
polycarbonate polyols (PO), it is preferable that the average
hydroxyl group functionality is at least 2.5. Suitable polyester
polyols are the known polycondensates of polyols (triols, tetraols)
with dicarboxylic and optionally polycarboxylic acids
(tricarboxylic/tetracarboxylic acids) or hydroxycarboxylic acids or
lactones.
[0090] In the preparation of the polyesters it is also possible to
use the corresponding polycarboxylic anhydrides or corresponding
polycarboxylic esters of lower alcohols instead of the free
polycarboxylic acids. Examples of suitable alcohols are
trimethylolpropane, glycerol, erythritol, pentaerythritol,
trimethylolbenzene or trishydroxyethyl isocyanurate.
[0091] Examples of suitable dicarboxylic include phthalic acid,
isophthalic acid, terephthalic acid, tetrahydrophthalic acid,
hexahydrophthalic acid, cyclohexanedicarboxylic acid, adipic acid,
azelaic acid, sebacic acid, glutaric acid, tetrachlorophthalic
acid, maleic acid, fumaric acid, itaconic acid acid, malonic acid,
suberic acid, 2-methylsuccinic acid, 3,3-diethylglutaric acid, and
2,2-dimethylsuccinic acid. The possible anhydrides of these acids
are likewise suitable. For the purposes of the present invention,
the anhydrides are consequently encompassed by the term "acid". It
is also possible to use monocarboxylic acids such as benzoic acid,
hexanecarboxylic acid or fatty acids, provided the average
functionality of the polyol is greater than two. Saturated
aliphatic or aromatic acids are preferred, such as adipic acid or
isophthalic acid. Polycarboxylic acids such as trimellitic acid may
be used in relatively small amounts. Examples of hydroxycarboxylic
acids that may be used as reactants in the preparation of a
polyester polyol having a terminal hydroxyl group include
hydroxycaproic acid, hydroxybutyric acid, hydroxydecanoic acid, or
hydroxystearic acid. Examples of suitable lactones include
.epsilon.-caprolactone or butyrolactone.
[0092] The suitable hydroxyl-containing polycarbonates can be
obtained by reacting carbonic acid derivatives, for example
diphenyl carbonate, dimethyl carbonate or phosgene, with polyols.
Examples include ethylene glycol, 1,2- and 1,3-propanediol, 1,3-
and 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, neopentyl
glycol, 1,4-bis(hydroxymethyl)cyclohexane, 2-methyl
1,3-propanediol, 2,2,4-trimethylpentane-1,3-diol, dipropylene
glycol, polypropylene glycols, dibutylene glycol, polybutylene
glycols, bisphenol A, tetrabromobisphenol A, but also
lactone-modified diols. The diol component preferably contains 40%
to 100% by weight of hexanediol, preferably 1,6-hexanediol and/or
hexanediol derivatives, particularly preferably those containing
ether or ester groups in addition to terminal OH groups. In order
to obtain the desired functionality of at least 2, the
polycarbonate polyols contain branching through the incorporation
of polyfunctional components, in particular low-molecular-weight
polyols.
[0093] Examples of compounds suitable for this purpose include
glycerol, trimethylolpropane, hexane-1,2,6-triol,
butane-1,2,4-triol, trimethylolpropane, pentaerythritol, quinitol,
marinitol, and sorbitol, methyl glycoside or
1,3,4,6-dianhydrohexitols. The polyacrylate copolymer can in
principle be produced by means of conventional free-radical
polymerization processes in the organic phase. The polyacrylate
copolymer is preferably produced in a multistage process, as has
been previously described in EP-A 0 947 557 or in EP-A 1 024 184.
In this process, a hydrophobic monomer mixture that is free of acid
groups or has a low content of acid groups is first metered in,
after which, at a later point in time in the polymerization, a more
hydrophilic monomer mixture containing acid groups is metered in,
with the more hydrophilic monomer mixture containing acid groups
that do not contain any monomers of type (M4) and (M5). The
copolymerization is generally carried out at 40 to 180.degree. C.,
preferably at 80 to 160.degree. C. Suitable initiators (I) for the
polymerization reaction include organic peroxides, for example
di-tert-butyl peroxide or tert-butyl peroxy-2-ethylhexanoate, and
azo compounds.
[0094] The amounts of initiator used depend on the desired
molecular weight. For reasons of operational safety and easier
handling, it is also possible for peroxide initiators to be used in
the form of a solution in suitable organic solvents of the type
already specified. The rate of addition of the initiator (I) in the
method of the invention can be regulated such that it lasts until
the end of the monomer feed, and the amounts of solvent in steps
one and two are chosen such that an organic solvent content of less
than 20% by weight results.
[0095] The amounts of the constituents are preferably calculated
such that a mass ratio (M1):(M2) from 9:1 to 6:1, more preferably a
mass ratio (M1):(M2) from 4:1 to 3:1, results. Likewise preferable
is a (M1):(M3) from 50:1 to 40:1, more preferably a (M1):(M3) from
35:1 to 30:1. Likewise preferable is a (M1):(M5) from 9:1 to 6:1,
more preferably a (M1):(M5) from 6:1 to 5:1.
[0096] The free-radical polymerization may be carried out in the
presence of a solvent or solvent/water mixture that is added to the
reaction vessel. All solvents known in coatings technology are
suitable as organic solvents, preference being given to those that
are customarily used as cosolvents in aqueous dispersions, for
example alcohols, ethers, ethers containing ether groups, esters,
ketones or nonpolar hydrocarbons or mixtures of these solvents. The
solvents are used in such amounts that their proportion in the
finished dispersion is 0% to 20% by weight, preferably 0.1% to 15%
by weight.
[0097] It is also possible to produce the polyacrylate copolymer by
the process described in EP-A 1 024 184, using a hydrophobic
copolymer as the initial charge. Instead of a multistage
polymerization process, it is also possible to execute the process
of the invention continuously (gradient polymerization), that is to
say a monomer mixture having a changing composition is added, the
fractions of hydrophilic (acid-functional) monomer being higher at
the end of the feed than at the start. The number-average molecular
weight Mn of the polyacrylate copolymers can be set by means of a
specific choice of operating parameters, for example the molar
ratio of monomer to initiator, for example the reaction time or the
temperature, to generally between 500 g/mol and 30 000 g/mol,
preferably between 1000 g/mol and 15 000 g/mol, more preferably
between 1500 g/mol and 10 000 g/mol. The hydroxyl group content of
the polyacrylate copolymers is in 100% form preferably 1.5% to
12.0% by weight, more preferably 2.0% to 10.0% by weight, and
particularly preferably 1.5% to 9.0% by weight.
[0098] Before, during or after the mixing of the polyacrylate
copolymers with the at least one uretdione-containing curing agent
(A), the acid groups present in the polyacrylate copolymers are at
least partially converted into their salt form, preferably through
addition of suitable neutralizing agents. Suitable neutralizing
agents are organic amines or water-soluble inorganic bases, for
example soluble metal hydroxides, metal carbonates, or metal
hydrogen carbonates, for example sodium hydroxide or potassium
hydroxide.
[0099] Examples of suitable amines are butyldiethanolamine,
N-methylmorpholine, triethylamine, ethyldiisopropylamine,
N,N-dimethylethanolamine, N,N-dimethylisopropanolamine,
N-methyldiethanolamine, diethylethanolamine, triethanolamine,
butanolamine, morpholine, 2-aminomethyl-2-methylpropanolamine or
isophoronediamine. In mixtures it is also possible to use a
proportion of ammonia. Particular preference is given to
triethanolamine, N,N-dimethylethanolamine, and
ethyldiisopropylamine.
[0100] In one embodiment, the mixture of free-radically
polymerizable monomers (M) does not contain: (M4) vinyl esters of
aliphatic carboxylic acids. Examples of such monomers to be avoided
are the esterification products of vinyl alcohol with linear or
branched aliphatic carboxylic acids such as vinyl acetate, vinyl
propionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl
octanoate, vinyl decanoate, vinyl neodecanoate, vinyl dodecanoate
(vinyl laurate) or vinyl stearate.
[0101] In a further embodiment, the mixture of free-radically
polymerizable monomers (M) does not contain: (M5): cycloaliphatic
esters of (meth)acrylic acid and/or vinylaromatics. Examples of
such monomers to be avoided are cyclohexyl (meth)acrylate,
cyclohexyl (meth)acrylates having alkyl ring substituents,
4-tert-butylcyclohexyl (meth)acrylate, norbornyl (meth)acrylate,
isobornyl (meth)acrylate, isobornyl acrylate and/or isobornyl
methacrylate and/or mixtures of the abovementioned monomers.
[0102] In another embodiment, the polyacrylate copolymer has in
100% form a hydroxyl group content of >1.5% by weight to
<12.0% by weight, preferably from >2.0% by weight to
<10.0% by weight. The hydroxyl group content may be calculated
by dividing the hydroxyl value, determined as described above, by
33.
[0103] In a further embodiment, the polyols (PO) have a hydroxyl
group content of >15% by weight to <35% by weight, preferably
from >20% by weight to <30% by weight. The hydroxyl group
content may be calculated by dividing the hydroxyl value,
determined as described above, by 33.
[0104] In a further embodiment, the polyols (PO) are polyester
polyols obtained from the reaction of an at least trifunctional
alcohol with a lactone. A particularly preferred polyol is obtained
from trimethylolpropane and .epsilon.-caprolactone. For example,
trimethylolpropane and .epsilon.-caprolactone may be reacted in a
weight ratio of >60:40 to <80:20, preferably >68:32 to
<72:28. Optionally, the reaction can take place in the presence
of a catalyst.
[0105] In a further embodiment, the monomers (M1), (M2), (M3),
(M4), and (M5) are used in the following amounts:
[0106] (M1) >25% by weight to <90% by weight, preferably
>30% by weight to <80% by weight,
[0107] (M2) >8% by weight to <50% by weight, preferably
>30% by weight to <45% by weight,
[0108] (M3) >1% by weight to <10% by weight, preferably
>2% by weight to <5% by weight,
[0109] optionally (M4) >1% by weight to <10% by weight,
preferably >1.5% by weight to <5% by weight,
[0110] optionally (M5) >5% by weight to <40% by weight,
preferably >10% by weight to <35% by weight; and optionally
the polyols (PO) in amounts of >5% by weight to <20% by
weight, preferably >8% by weight to <15% by weight, based on
the total weight of the solids in the dispersion, the amounts
stated adding up to 100% by weight.
[0111] The polyurethane resin used according to the invention is
preferably produced in such a way that a polyacrylate copolymer (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 carboxyl groups present in the polyacrylate copolymer (B) are
neutralized with suitable neutralizing agents preferably to at
least 50%, more preferably 80% to 130%, particularly preferably 95
to 125%, 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.
[0112] 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.
[0113] Preference is given to amines such as triethylamine,
triethanolamine, diisopropylhexylamine, and dimethylethanolamine,
and particular preference to triethanolamine and
dimethylethanolamine.
[0114] In accordance with the present invention, the neutralizing
agents are to be included in the group of auxiliaries and additives
(D).
[0115] 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.
[0116] 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-ethylhexyl octoate 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.
EXAMPLES
[0117] Raw Materials Employed:
[0118] Dowanol PnB: propylene glycol mono-n-butyl ether, from
Dow
[0119] Peroxan DB: di-tert-butyl peroxide from Pergan.
[0120] Solvent Naphtha 100: an aromatic solvent, CAS: 64 742-95-6,
from Azelis.
[0121] Veova 9: Versatic acid vinyl ester from Momentive.
[0122] Analytical Methods Used:
[0123] 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.
[0124] NCO contents were determined titrimetrically in accordance
with DIN EN ISO 11909:2007-05.
[0125] OH values were determined titrimetrically in accordance with
DIN EN ISO 4629-2:2015-02.
[0126] The determination of acid values titrimetrically in
accordance with DIN EN ISO 2114:2002-06.
[0127] Solids contents were determined in a circulating-air oven in
accordance with DIN EN ISO 3251:2008-06, method B.
[0128] Average particle sizes (MPS) were determined using a
Zetasizer Nano from Malvern (DE) in accordance with DIN ISO
13321:2004-10.
[0129] 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.
[0130] Residual monomer contents were measured in accordance with
DIN EN ISO 10283 by gas chromatography with an internal
standard.
[0131] Pendulum hardness was measured on a standardized coil test
plate (coil coating black--CS 200570, from Heinz Zanders
Pruf-Blech-Logistik) in accordance with DIN EN ISO 1522:2007-04
using a Konig pendulum.
[0132] Chemical resistance was measured on a standardized coil test
plate (coil coating black--CS 200570, from Heinz Zanders
Pruf-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:
[0133] 0 no, i.e. no noticeable damage
[0134] 1 very few areas of damage, i.e. small, just about
significant number
[0135] 2 a few areas of damage, i.e. small, but significant
number
[0136] 3 moderate number of areas of damage
[0137] 4 considerable number of areas of damage
[0138] 5 very many areas of damage
[0139] Unless explicitly described otherwise, all percentages refer
to percentages by weight.
[0140] Preparation of a Uretdione Group-Containing Crosslinker
(Crosslinker 1, Preparation Example)
[0141] To 1000 g (4.50 mol) of isophorone diisocyanate (IPDI) were
successively added at room temperature under dry nitrogen, with
stirring, 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.
[0142] This yielded a light yellow uretdione polyisocyanate having
a free NCO group content of 17.0%, a monomeric IPDI content of
0.4%, and a viscosity of more than 200 000 mPas.
[0143] 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 to a
value of 0.8% after 7 to 8 h. The reaction mixture was solidified
by pouring it onto a metal sheet, comminuted, and then dissolved in
Dowanol PnB to give a solution with a solids content of 60% by
weight.
Examples 1 to 4
Example 1
TABLE-US-00001 [0144] TABLE 1 Weight (g) Component 1 DOWANOL PnB
1567 Component 2 PEROXAN DB 33 DOWANOL PnB 33 Component 3 METHYL
METHACRYLATE 1243 HYDROXYETHYL METHACRYLATE 2419 n-BUTYL
METHACRYLATE 592 n-BUTYL ACRYLATE 723 ISOBORNYL METHACRYLATE 1701
BUTANEDIOL MONOACRYLATE 836 STYRENE 573 Component 4 PEROXAN DB 140
DOWANOL PnB 140 Component 5 BUTANEDIOL MONOACRYLATE 296 METHYL
METHACRYLATE 449 HYDROXYETHYL METHACRYLATE 467 n-BUTYL ACRYLATE 379
ACRYLIC ACID 316 Component 6 PEROXAN DB 33 DOWANOL PnB 60 Total
amount 12000
[0145] Component 1 from table 1 was weighed into a stirring
apparatus under nitrogen and heated to 138.degree. C. Component 2
was then metered in evenly at 138.degree. C. over a period of 20
minutes. After this, component 3 and component 4 were immediately
metered in evenly at 138.degree. C. in parallel over a period of 4
h 30 min. At the end of the addition, the reaction mixture was held
at 138.degree. C. for 30 min. Finally, component 5 and component 6
were metered in evenly at 138.degree. C. in parallel over a period
of 1 h 30 min. At the end of the addition, the reaction mixture was
held at 138.degree. C. for a further 1 h. After cooling, a pale
yellowish, highly viscous polyacrylate solution was obtained. 500 g
of this solution was weighed into a stirring apparatus under
nitrogen and heated to 70.degree. C. After homogenizing, 567 g of
the 60% solution of crosslinker 1 in Dowanol PnB was added and the
mixture was homogenized again at 70.degree. C. for 30 min, followed
by addition of a mixture of 21.5 g of triethanolamine and 4.3 g of
dimethylethanolamine. The mixture was stirred at 70.degree. C. for
a further 30 min and then 463 g of distilled water was stirred in
to the mixture. Fine adjustment of the viscosity to approx. 2000
mPas afforded a dispersion having the following properties:
TABLE-US-00002 Solids content 43.7% by weight Acid value (100%) 13
mg KOH/g OH content (100%, calculated) 2.8% by weight Average
particle size 230 nm Viscosity 2030 mPas pH 7.5 The dispersion
remained stable at 23.degree. C. for 10 months.
Example 2
[0146] 500 g of polyacrylate solution from example 1 was weighed
into a stirring apparatus under nitrogen and heated to 70.degree.
C. After homogenizing, 283 g of the 60% solution of crosslinker 1
in Dowanol PnB was added and the mixture was homogenized again at
70.degree. C. for 30 min, followed by addition of a mixture of 21.5
g of triethanolamine and 4.3 g of dimethylethanolamine. The mixture
was stirred at 70.degree. C. for a further 30 min and then 407 g of
distilled water was stirred into it. Fine adjustment of the
viscosity to approx. 2000 mPas afforded a dispersion having the
following properties:
TABLE-US-00003 Solids content 41.7% by weight Acid value (100%)
16.6 mg KOH/g OH content (100%, calculated) 3.6% by weight Average
particle size 175 nm Viscosity 2360 mPas pH 7.5 The dispersion
remained stable at 23.degree. C. for 10 months.
Example 3
TABLE-US-00004 [0147] TABLE 2 Weight (g) Component 1 SOLVENT
NAPHTHA 100 900 BUTYLGLYCOL 648 Component 2 PEROXAN DB 33
BUTYLGLYCOL 33 Component 3 METHYL METHACRYLATE 3669 HYDROXYETHYL
METHACRYLATE 1816 n-BUTYL ACRYLATE 2603 Component 4 PEROXAN DB 139
BUTYLGLYCOL 139 Component 5 METHYL METHACRYLATE 520 HYDROXYETHYL
METHACRYLATE 734 n-BUTYL ACRYLATE 408 ACRYLIC ACID 245 Component 6
PEROXAN DB 33 BUTYLGLYCOL 80 Total amount 12000
[0148] Component 1 from table 2 was weighed into a stirring
apparatus under nitrogen and heated to 138.degree. C. Component 2
was then metered in evenly at 138.degree. C. over a period of 20
minutes. After this, component 3 and component 4 were immediately
metered in evenly at 138.degree. C. in parallel over a period of 4
h 30 min. At the end of the addition, the reaction mixture was held
at 138.degree. C. for 30 min. Finally, component 5 and component 6
were metered in evenly at 138.degree. C. in parallel over a period
of 1 h 30 min. At the end of the addition, the reaction mixture was
held at 138.degree. C. for a further 1 h. After cooling, a pale
yellowish, highly viscous polyacrylate solution was obtained to
100.degree. C., the reaction mixture was transferred to the
appropriate container(s).
[0149] 552 g of this solution was weighed into a stirring apparatus
under nitrogen and heated to 70.degree. C. After homogenizing, 471
g of the 60% solution of crosslinker 1 in Dowanol PnB was added and
the mixture was homogenized again at 70.degree. C. for 30 min,
followed by addition of 14.6 g of dimethylethanolamine. The mixture
was stirred at 70.degree. C. for a further 30 min and then 466 g of
distilled water was stirred in. Fine adjustment of the viscosity to
approx. 2000 mPas afforded a stable dispersion having the following
properties:
TABLE-US-00005 Solids content 46.1% by weight Acid value (100%)
16.3 mg KOH/g OH content (100%, calculated) 2.1% by weight Average
particle size 225 nm Viscosity 1110 mPas pH 8.2 The dispersion
remained stable at 23.degree. C. for 5 months.
Example 4
TABLE-US-00006 [0150] TABLE 3 Weight (g) Component 1 DOW ANOL PnB
3438 Component 2 PEROXAN DB 33 DOWANOL PnB 33 Component 3 STYRENE
570 METHYL METHACRYLATE 1566 HYDROXYETHYL METHACRYLATE 1601 n-BUTYL
ACRYLATE 341 ISOBORNYL METHACRYLATE 1520 n-BUTYL METHACRYLATE 1208
VEOVA 9 1251 Component 4 PEROXAN DB 118 DOWANOL PnB 321 Total
amount 12000
[0151] Component 1 from table 3 was weighed into a stirring
apparatus under nitrogen and heated to 148.degree. C. Component 2
was then metered in evenly at 148.degree. C. over a period of 20
minutes. After this, component 3 and component 4 were immediately
metered in evenly at 148.degree. C. in parallel over a period of 6
h. At the end of the addition, the reaction mixture was held at
148.degree. C. for 60 min. After cooling to 80.degree. C., the
polyacrylate solution was transferred to the appropriate
container(s).
TABLE-US-00007 TABLE 4 Raw material Weights Component 1
Polyacrylate solution from table 3 1993 Component 2 PEROXAN DB 36
DOWANOL PnB 36 72 Component 3 2-ETHYLHEXYL ACRYLATE 377
HYDROXYETHYL ACRYLATE 1931 n-BUTYL METHACRYLATE 1308 ISOBORNYL
METHACRYLATE 2951 n-BUTYL ACRYLATE 338 BUTANEDIOL MONOACRYLATE 555
Component 4 PEROXAN DB 129 DOWANOL PnB 154 Component 5 METHYL
METHACRYLATE 533 HYDROXYETHYL ACRYLATE 799 n-BUTYL ACRYLATE 411
METHACRYLIC ACID 333 Component 6 PEROXAN DB 36 DOWANOL PnB 80 Total
amount 12000
[0152] Component 1 from table 4 was weighed into a stirring
apparatus under nitrogen and heated to 144.degree. C. Component 2
was then metered in evenly at 144.degree. C. over a period of 20
minutes. After this, component 3 and component 4 were immediately
metered in evenly at 144.degree. C. in parallel over a period of 4
h 30 min. At the end of the addition, the reaction mixture was held
at 144.degree. C. for 5 min. Finally, component 5 and component 6
were metered in evenly at 144.degree. C. in parallel over a period
of 1 h 30 min. At the end of the addition, the reaction mixture was
held at 144.degree. C. for a further 1 h. After cooling, a pale
yellowish, highly viscous polyacrylate solution was obtained.
[0153] 304 g of this solution was weighed into a stirring apparatus
under nitrogen and heated to 70.degree. C. After homogenizing, 385
g of the 60% solution of crosslinker 1 in Dowanol PnB was added and
the mixture was homogenized again at 70.degree. C. for 30 min,
followed by addition of 11 g of dimethylethanolamine. The mixture
was stirred at 70.degree. C. for a further 30 min and then 324 g of
distilled water was stirred into it. Fine adjustment of the
viscosity to approx. 2000 mPas afforded a dispersion having the
following properties:
TABLE-US-00008 Solids content 42.6% by weight Acid value (100%) 18
mg KOH/g OH content (100%, calculated) 2.5% by weight Average
particle size 287 nm Viscosity 2030 mPas pH 8.7 The dispersion
remained stable at 23.degree. C. for 5 months.
[0154] Tests of Coating Properties:
[0155] Clearcoats were produced from the preceding examples 1 to 4.
(all weights in g):
TABLE-US-00009 TABLE 5 Inventive examples 5 to 8 Example 5 6 7 8 1
10.00 2 10.00 3 10.00 4 10.00
[0156] The dispersions were homogenized in a SpeedMixer at 2000 rpm
for 1 minute 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 for 5 min at room temperature, baked
for 30 min at 180.degree. C., and then stored for 24 hours at room
temperature. The performance of the stored films was assessed
(table 6).
TABLE-US-00010 TABLE 6 Tests of the coating properties of the
inventive examples 5-8 Example 5 6 7 8 Appearance of the coating
(visual examination) clear, glossy clear, glossy clear, glossy
silk-matt Film thickness (dry, .mu.) 60 50 50 40 Pendulum hardness
(s) 188 196 189 204 Resistance to xylene (5 minutes) 3 2 3 2
Deionized water (1 hour) 1 0-1 0-1 0-1
[0157] As can be seen from table 6, the uretdione-containing
dispersions of the invention afford hard and resistant coatings.
Both glossy and silk-matt coatings can be produced from the
uretdione-containing dispersions of the invention.
* * * * *