U.S. patent application number 13/176911 was filed with the patent office on 2013-01-10 for waterborne polyurethane coating compositions.
This patent application is currently assigned to Bayer MaterialScience LLC. Invention is credited to Abdullah Ekin, Torsten Pohl, Raymond Stewart, Ramesh Subramanian.
Application Number | 20130011591 13/176911 |
Document ID | / |
Family ID | 47388245 |
Filed Date | 2013-01-10 |
United States Patent
Application |
20130011591 |
Kind Code |
A1 |
Ekin; Abdullah ; et
al. |
January 10, 2013 |
WATERBORNE POLYURETHANE COATING COMPOSITIONS
Abstract
Aqueous polyurethane coating compositions are disclosed in this
specification. The aqueous polyurethane coating compositions
contain a polycarbonate-polyurethane resin component, an aminoplast
resin component, and a polyacrylic polyol component.
Inventors: |
Ekin; Abdullah; (Imperial,
PA) ; Stewart; Raymond; (Lawrence, PA) ;
Subramanian; Ramesh; (Coraopolis, PA) ; Pohl;
Torsten; (Leverkusen, DE) |
Assignee: |
Bayer MaterialScience LLC
Pittsburgh
PA
|
Family ID: |
47388245 |
Appl. No.: |
13/176911 |
Filed: |
July 6, 2011 |
Current U.S.
Class: |
428/34.7 ;
428/425.6; 524/262; 524/265; 524/507 |
Current CPC
Class: |
Y10T 428/31601 20150401;
C09D 175/06 20130101; Y10T 428/131 20150115; C03C 17/322 20130101;
Y10T 428/1317 20150115; C09D 175/06 20130101; C08L 61/20 20130101;
C09D 133/14 20130101; Y10T 428/1321 20150115 |
Class at
Publication: |
428/34.7 ;
524/507; 524/262; 524/265; 428/425.6 |
International
Class: |
C09D 175/06 20060101
C09D175/06; C08K 5/5435 20060101 C08K005/5435; B32B 17/10 20060101
B32B017/10; C09D 161/28 20060101 C09D161/28; C09D 133/14 20060101
C09D133/14; C08K 5/544 20060101 C08K005/544; C08K 5/548 20060101
C08K005/548; C09D 175/08 20060101 C09D175/08 |
Claims
1. An aqueous polyurethane coating composition comprising: (a) a
water-dilutable hydroxy-functional polyacrylic resin comprising a
reaction product of: (A1) an olefinically unsaturated
hydroxy-functional monomer; (A2) an olefinically unsaturated
monomer that comprises an ionic group or a potentially ionic group;
and (A3) an olefinically unsaturated monomer that does not comprise
an ionic group, a potentially ionic group, or a hydroxyl group; (b)
a water-dilutable aminoplast.resin; and (c) a water-dilutable
polycarbonate-polyurethane resin, wherein the
polycarbonate-polyurethane resin is non-functional.
2. The aqueous polyurethane coating composition of claim 1, wherein
the hydroxy-functional polyacrylic resin component (a) has a weight
average molecular weight of 500-100000, a hydroxyl number of 16.5
to 264 mg KOH/g and an acid number of 5 to 125 mg KOH/g.
3. The aqueous polyurethane coating composition of claim 1, wherein
the aminoplast resin component (b) comprises a
melamine-formaldehyde condensation product.
4. The aqueous polyurethane coating composition of claim 1, wherein
the aminoplast resin component (b) comprises an oligomeric
methylated melamine-formaldehyde condensation product comprising
imino groups, methoxymethyl groups, and methylol groups.
5. The aqueous polyurethane coating composition of claim 4, wherein
an equivalent ratio of methylol groups and alkoxylmethyl groups of
component (b) to hydroxyl groups of component (a) is at least
0.05:1.
6. The aqueous polyurethane coating composition of claim 1, wherein
the polycarbonate-polyurethane resin component (c) comprises a
reaction product of a polycarbonate polyol and a polyisocyanate
selected from the group consisting of
4,4'-diisocyanatodicyclohexylmethane, isophorone diisocyanate,
1,6-hexamethylene diisocyanate, and
1-methyl-2,4(2,6)-diisocyanatocyclohexane.
7. The aqueous polyurethane coating composition of claim 6, wherein
the polycarbonate polyol has a number average molecular weight
range 500 to 6000.
8. The aqueous polyurethane coating composition of claim 1, wherein
the polycarbonate-polyurethane resin component (c) is characterized
by a glass transition temperature of between -60.degree. C. and
0.degree. C.
9. The aqueous polyurethane coating composition of claim 1, wherein
the polycarbonate-polyurethane resin component (c) is characterized
by a viscosity at 25.degree. C. of less than 500 mPas in an 38% to
42% solids aqueous dispersion.
10. The aqueous polyurethane coating composition of claim 1,
comprising: 99% to 1% by weight on a solids basis of the
water-dilatable hydroxy-functional polyacrylic resin and a
water-dilutable aminoplast resin; and 1% to 99% by weight on a
solids basis of the water-dilutable polycarbonate-polyurethane
resin wherein the weight percents total 100% by weight.
11. The aqueous polyurethane coating composition of claim 10,
comprising: 40% to 90% by weight on a solids basis of the
water-dilutable hydroxy-functional polyacrylic resin; a
water-dilutable aminoplast resin; and 60% to 10% by weight on a
solids basis of the water-dilutable polycarbonate-polyurethane
resin wherein the weight percents total 100% by weight.
12. The aqueous polyurethane coating composition of claim 1,
wherein the weight ratio on a solids basis of the
hydroxy-functional polyacrylic resin to the aminoplast resin is
from 55:45 to 85:15.
13. The aqueous polyurethane coating composition of claim 12,
wherein the weight ratio on a solids basis of the
hydroxy-functional polyacrylic resin to the aminoplast resin is
from 60:40 to 70:30.
14. The aqueous polyurethane coating composition of claim 1,
further comprising a silane-functional adhesion promoter.
15. The aqueous polyurethane coating composition of claim 14,
wherein the adhesion promoter is selected from the group consisting
of .gamma.-mercaptopropyl-trimethoxysilane,
3-aminopropyltriethoxysilane, 3-aminopropylsilane hydrolysate,
3-glycidyloxypropyltriethoxysilane, and combinations of any
thereof.
16. The aqueous polyurethane coating composition of claim 1,
further comprising an additional polyol resin selected from the
group consisting of water-dispersible hydroxy-functional polyester
resins and water-dispersible hydroxy-functional
polyether-polyurethane resins.
17. A substrate at least partially coated with the coating
composition of claim 1.
18. The substrate of claim 17, wherein the coating exhibits
microhardness of no greater than 90 N/mm.sup.2, direct impact
strength of at least 60 in-lbs, and reverse impact strength of at
least 20 in-lbs.
19. A glass substrate at least partially coated with the coating
composition of claim 1.
20. A glass container at least partially coated with the coating
composition of claim 1.
Description
TECHNICAL FIELD
[0001] This disclosure relates to one-component waterborne
polyurethane coating compositions and to the use of such
compositions for coating substrates.
BACKGROUND
[0002] Glass substrates may be coated, for example, to provide a
decorative effect or to enhance substrate properties. For instance,
glass substrates may be coated to provide anti-shattering
properties, abrasion resistance, increased elasticity, and solvent
resistance. Glass containers, for example, may benefit from clear
coatings that provide mechanical protection to the external
surfaces to help minimize mechanical damage, such as scuffing or
marring, to the containers during transportation, storage, filling
operations, and distribution.
SUMMARY
[0003] Embodiments disclosed in this specification are directed to
aqueous polyurethane coating compositions. The aqueous polyurethane
coating compositions comprise a polyol resin, an aminoplast resin,
and a polycarbonate-polyurethane resin.
[0004] In various embodiments, an aqueous polyurethane coating
composition comprises: (a) a water-dilutable hydroxy-functional
polyacrylic resin; (b) a water-dilutable aminoplast resin; and (c)
a water-dilutable polycarbonate-polyurethane resin. The
water-dilutable hydroxy-functional polyacrylic resin comprises a
reaction product of: (A1) an olefinically unsaturated
hydroxy-functional monomer; (A2) an olefinically unsaturated
monomer that comprises an ionic group or a potentially ionic group;
and (A3) an olefinically unsaturated monomer that does not comprise
an ionic, potentially ionic group, or a hydroxyl group. The
hydroxy-functional polyacrylic resin component (a) and the
aminoplast resin component (b) react at temperatures above ambient
temperature to form crosslinks. The polycarbonate-polyurethane
resin is non-functional.
[0005] It is understood that the invention disclosed and described
in this specification is not limited to the embodiments summarized
in this Summary.
DESCRIPTION
[0006] Various embodiments are described and illustrated in this
specification to provide an overall understanding of the structure,
function, operation, manufacture, and use of the disclosed products
and processes. It is understood that the various embodiments
described and illustrated in this specification are non-limiting
and non-exhaustive. Thus, the invention is not limited by the
description of the various non-limiting and non-exhaustive
embodiments disclosed in this specification. Rather, the invention
is defined solely by the claims. The features and characteristics
illustrated and/or described in connection with various embodiments
may be combined with the features and characteristics of other
embodiments. Such modifications and variations are intended to be
included within the scope of this specification. As such, the
claims may be amended to recite any features or characteristics
expressly or inherently described in, or otherwise expressly or
inherently supported by, this specification. Further, Applicant
reserves the right to amend the claims to affirmatively disclaim
features or characteristics that may be present in the prior art.
Therefore, any such amendments comply with the requirements of 35
U.S.C. .sctn.112, first paragraph, and 35 U.S.C. .sctn.132(a). The
various embodiments disclosed and described in this specification
can comprise, consist of, or consist essentially of the features
and characteristics as variously described herein.
[0007] Any patent, publication, or other disclosure material
identified herein is incorporated by reference into this
specification in its entirety unless otherwise indicated, but only
to the extent that the incorporated material does not conflict with
existing definitions, statements, or other disclosure material
expressly set forth in this specification. As such, and to the
extent necessary, the express disclosure as set forth in this
specification supersedes any conflicting material incorporated by
reference herein. Any material, or portion thereof, that is said to
be incorporated by reference into this specification, but which
conflicts with existing definitions, statements, or other
disclosure material set forth herein, is only incorporated to the
extent that no conflict arises between that incorporated material
and the existing disclosure material. Applicant reserves the right
to amend this specification to expressly recite any subject matter,
or portion thereof, incorporated by reference herein.
[0008] Reference throughout this specification to "various
non-limiting embodiments," or the like, means that a particular
feature or characteristic may be included in an embodiment. Thus,
use of the phrase "in various non-limiting embodiments," or the
like, in this specification does not necessarily refer to a common
embodiment, and may refer to different embodiments. Further, the
particular features or characteristics may be combined in any
suitable manner in one or more embodiments. Thus, the particular
features or characteristics illustrated or described in connection
with various embodiments may be combined, in whole or in part, with
the features or characteristics of one or more other embodiments
without limitation. Such modifications and variations are intended
to be included within the scope of the present specification. In
this manner, the various embodiments described in this
specification are non-limiting and non-exhaustive.
[0009] In this specification, other than where otherwise indicated,
all numerical parameters are to be understood as being prefaced and
modified in all instances by the term "about", in which the
numerical parameters possess the inherent variability
characteristic of the underlying measurement techniques used to
determine the numerical value of the parameter. At the very least,
and not as an attempt to limit the application of the doctrine of
equivalents to the scope of the claims, each numerical parameter
described in the present description should at least be construed
in light of the number of reported significant digits and by
applying ordinary rounding techniques.
[0010] Also, any numerical range recited in this specification is
intended to include all sub-ranges subsumed within the recited
range. For example, a range of "1 to 10" is intended to include all
sub-ranges between (and including) the recited minimum value of 1
and the recited maximum value of 10, that is having a minimum value
equal to or greater than 1 and a maximum value'equal to or less
than 10. Any maximum numerical limitation recited in this
specification is intended to include all lower numerical
limitations subsumed therein and any minimum numerical limitation
recited in this specification is intended to include all higher
numerical limitations subsumed therein. Accordingly, Applicant
reserves the right to amend this specification, including the
claims, to expressly recite any sub-range subsumed within the
ranges expressly recited herein. All such ranges are intended to be
inherently described in this specification such that amending to
expressly recite any such sub-ranges would comply with the
requirements of 35 U.S.C. .sctn.112, first paragraph, and 35 U.S.C.
.sctn.132(a).
[0011] The grammatical articles "one", "a", "an", and "the", as
used in this specification, are intended to include "at least one"
or "one or more", unless otherwise indicated. Thus, the articles
are used in this specification to refer to one or more than one
(i.e., to "at least one") of the grammatical objects of the
article. By way of example, "a component" means one or more
components, and thus, possibly, more than one component is
contemplated and may be employed or used in an implementation of
the described embodiments. Further, the use of a singular noun
includes the plural, and the use of a plural noun includes the
singular, unless the context of the usage requires otherwise.
[0012] The various embodiments disclosed and described in this
specification provide waterborne (i.e., aqueous) polyurethane
coating compositions that exhibit properties beneficial for
substrates such as, for example, glass substrates. The aqueous
polyurethane coating compositions disclosed herein provide cured
coating films exhibiting decreased hardness, increased flexibility,
increased impact resistance, good substrate adhesion in severe
environments, increased abrasion resistance, and increased solvent
resistance. The aqueous polyurethane coating compositions provide
beneficial properties to substrates such as, for example, glass
substrates. The aqueous polyurethane coating compositions may be
one-component compositions that are free of blocking agents. The
aqueous polyurethane coating compositions may comprise aminoplast
crosslinking components for thermal curing.
[0013] One-component coating compositions comprise pre-mixed
compositions that have acceptable pot-life and storage stability,
and are applied to substrates and cured under specific conditions
such as, for example, at elevated temperatures or upon exposure to
ultraviolet light. One-component systems include, for example,
hydroxy-functional resins crosslinked with alkoxylated aminoplast
resins or reversibly blocked isocyanates. In contrast,
two-component coating compositions comprise two separate and
mutually reactive components that are mixed immediately prior to
application to substrate. The separate components respectively
contain ingredients that are reactive under ambient conditions and
that begin appreciable formation of cured resin immediately upon
mixture. Therefore, the two components must remain separated until
immediately before application due to limited pot-life.
[0014] U.S. Pat. No. 4,280,944, which is incorporated by reference
into this specification, describes aqueous polyether-based
polyurethane dispersions, which, by virtue of the free hydroxyl
groups and blocked isocyanate groups contained therein, constitute
a one-component system, which can be thermally cured. However, it
may be desirable to provide one-component aqueous polyurethane
dispersion coating compositions that do not contain blocking agents
and are thermally curable. Use of melamine as a crosslinker is one
alternative to crosslink hydroxy-functional polyacrylic
polyurethane dispersions.
[0015] EP-A 519,074, which is incorporated by reference into this
specification, discloses an aqueous glass coating composition that
is applied in two coats, wherein the topcoat contains three main
components: an aqueous polyurethane dispersion, an aqueous epoxy
resin, and an aqueous melamine/formaldehyde resin. The polyurethane
dispersion achieves the required final properties only after the
addition of substantial quantities of the other two resins.
Accordingly, the disclosed coating composition is a multi-component
composition as opposed to a one-component composition.
[0016] Aminoplast crosslinking components, such as, for example,
melamine crosslinkers, may be added to waterborne polyurethane
coating compositions to provide one-component thermally-curable
waterborne polyurethane coating compositions that are free of
blocking agents. Generally, the addition of aminoplast crosslinking
components increases the hardness of the cured coating film. As
such, the use of aminoplast crosslinking components may result in
undesirable coating properties such as, for example, increased
brittleness, decreased impact resistance, and decreased abrasion
resistance.
[0017] These effects may be particularly problematic for substrates
such as, for example, glass materials, which may readily show
mechanical surface damage of relatively hard and brittle coating
films on the substrate. Further, relatively hard and brittle
coating films tend to exhibit increased mechanical abrasion, wear,
and erosion. However, the present inventors discovered
one-component thermally-curable aqueous polyurethane coating
compositions that are free of blocking agents, that contain
aminoplast crosslinking components, and that exhibit low hardness
and high flexibility, high impact resistance and toughness, and
high abrasion resistance.
[0018] The one-component thermally-curable aqueous polyurethane
coating compositions disclosed herein may comprise: (a) a polyol
resin; (b) an aminoplast resin, and (c) a
polycarbonate-polyurethane resin. As used herein, the term
"polyurethane" refers to polymeric or oligomeric materials
comprising urethane groups, urea groups, or both. The term
"polyurethane" also refers to polymeric or oligomeric resins or
crosslinked polymer networks comprising urethane groups, urea
groups, or both. As used herein, the term "polyol" refers to
compounds comprising at least two unreacted hydroxyl groups.
Polyols may include monomers, polymers and/or oligomers comprising
at least two pendant and/or terminal hydroxyl groups.
[0019] In various non-limiting embodiments, the polyol resin
component (a) of the aqueous polyurethane coating compositions
disclosed herein may comprise a water-dilutable hydroxy-functional
polyacrylic resin. As used herein, the term "polyacrylic resin"
refers to oligomeric or polymeric macromolecules comprising
residues of olefinically unsaturated monomers. Water-dilutable
hydroxy-functional polyacrylic resins may comprise oligomers or
polymers of olefinically unsaturated monomers that comprise
hydroxyl groups; sulfonic acid groups and/or carboxyl groups;
sulfonate groups and/or carboxylate groups; or other ionic groups
or potentially ionic groups.
[0020] In various non-limiting embodiments, the polyol resin
component (a) is a water-dilutable hydroxy-functional polyacrylic
resin. As used herein, the term "water-dilutable" refers to
solubility as a molecular solution in water, or dispersability as a
dispersion, emulsion, suspension, colloid, sol, or the like, in
water, with or without external dispersants, emulsifiers,
surfactants, co-solvents, or the like. As used herein, the term
"hydroxy-functional" refers to molecules comprising at least one
unreacted hydroxyl group.
[0021] In various non-limiting embodiments, the polyol resin
component (a) of the aqueous polyurethane coating compositions
disclosed herein may comprise a water-dilutable hydroxy-functional
polyacrylic resin. As used herein, the term "polyacrylic resin"
refers to oligomeric or polymeric macromolecules comprising
residues of olefinically unsaturated monomers. Water-dilutable
hydroxy-functional polyacrylic resins may comprise oligomers or
polymers of olefinically unsaturated monomers that comprise
hydroxyl groups; sulfonic acid groups and/or carboxyl groups;
sulfonate groups and/or carboxylate groups; or other ionic groups
or potentially ionic groups.
[0022] Water-dilutable hydroxy-functional polyacrylic resins may be
produced by the copolymerization of: (A1) olefinically unsaturated
hydroxy-functional monomers; (A2) olefinically unsaturated monomers
that comprise ionic groups or potentially ionic groups; and (A3)
other olefinically unsaturated monomers. In various non-limiting
embodiments, the copolymerization of components (A1) through (A3)
is carried out with component (A2) in potentially ionic form (e.g.,
comprising non-ionic sulfonic acid groups or carboxyl groups), that
are at least partially converted to ionic form after
copolymerization.
[0023] In various non-limiting embodiments, olefinically
unsaturated hydroxy-functional monomers (A1) may comprise, for
example, hydroxyalkyl esters of acrylic acid or methacrylic acid
(e.g., comprising 2 to 4 carbon atoms in the hydroxyalkyl radical)
such as 2-hydroxyethyl (meth)acrylate, the isomeric hydroxypropyl
(meth)acrylates formed by addition of propylene oxide onto
(meth)acrylic acid, the isomeric hydroxybutyl (meth)acrylates; and
combinations of any thereof.
[0024] In various non-limiting embodiments, olefinically
unsaturated monomers that comprise ionic groups or potentially
ionic groups (A2) may comprise, for example, a carbonyl group or
sulfonic acid group. Suitable monomers (A2) include, for example,
olefinically unsaturated mono-carboxylic acids or di-carboxylic
acids having a molecular weight of 72 to 207 such as, for example,
acrylic acid; methacrylic acid; maleic acid; itaconic acid; and
combinations of any thereof. Suitable monomers (A2) also include,
for example, olefinically unsaturated compounds comprising sulfonic
acid groups such as, for example 2-acrylamido-2-methyl
propanesulfonic acid. Mixtures of any olefinically unsaturated
monomers that comprise ionic groups or potentially ionic groups may
also be used.
[0025] In various non-limiting embodiments, other olefinically
unsaturated monomers (A3) may comprise, for example, olefinically
unsaturated compounds that do not comprise ionic, potentially ionic
groups, or hydroxyl groups. Suitable monomers (A3) include, for
example, esters of acrylic acid or methacrylic acid comprising 1 to
18, or 1 to 8, carbon atoms in the alcohol radical, such as, for
example methyl (meth)acrylate; ethyl (meth)acrylate; isopropyl
(meth)acrylate; n-propyl (meth)acrylate; n-butyl (meth)acrylate;
2-ethylhexyl (meth)acrylate; n-stearyl (meth)acrylate; and
combinations of any thereof. Suitable monomers (A3) also include,
for example, styrene; alkyl-substituted styrenes; propenylbenzene;
acrylonitrile; methacrylonitrile; vinyl acetate; vinyl stearate;
epoxy-functional co-monomers such as glycidyl acrylate or glycidyl
methacrylate; N-methoxymethacrylamide; methacrylamide; and
combinations of any thereof.
[0026] Water-dilutable hydroxy-functional polyacrylic resins
comprising polymerization products of components (A1) through (A3)
may be produced using polymerization methods such as, for example,
bulk, solution, emulsion and suspension polymerization techniques
using free-radical initiators. Suitable processes are described,
for example, in U.S. Pat. No. 5,331,039, which is incorporated by
reference into this specification.
[0027] Olefinically unsaturated hydroxy-functional monomers. (A1)
may be used in quantities sufficient to obtain desired hydroxyl
numbers such as, for example, hydroxyl group contents of 0.5% to 8%
by weight, or 1% to 5% by weight, of the water-dilutable
hydroxy-functional polyacrylic resins. For instance,
hydroxy-functional monomers (A1) may be used in quantities of 3% to
75% by weight, or 6% to 47% by weight, based on the total weight of
the monomers (A1) through (A3). In various non-limiting
embodiments, the quantities of hydroxy-functional monomers (A1) may
be selected so that, on a statistical average, the polyacrylic
copolymers formed comprise at least two hydroxyl groups per
macromolecule.
[0028] In various non-limiting embodiments, olefinically
unsaturated monomers (A2) that comprise ionic groups or potentially
ionic groups may at least partially impart water-dilutability
(e.g., aqueous solubility or aqueous dispersability) to
water-dilutable hydroxy-functional polyacrylic resins by covalently
incorporating into the macromolecules, increasing the
hydrophilicity of the macromolecules. The quantity of monomers (A2)
used, and the degree of deprotonation of unreacted sulfonic acid or
carboxyl groups, should be sufficient to produce a stable aqueous
dispersion or aqueous solution, with or without external
emulsifiers, dispersants, co-solvents, and the like, as
appropriate. For instance, in various non-limiting embodiments,
monomers (A2) may be used in quantities of 0.3% to 30% by weight,
or 1% to 20% by weight, based on the total weight of the monomers
(A1) through (A3).
[0029] Depending upon the molecular weight of the polyacrylic
resins, their content of ionic groups or potentially ionic groups,
and/or any the presence of emulsifiers, co-solvents, and the like,
waterborne systems comprising the polyacrylic resins may be either
colloidal dispersions, molecular solutions, or mixtures of both. In
embodiments using relatively low amounts of monomers (A2), aqueous
dispersions (colloidal) generally form, but may comprise a small
amount of polymer in aqueous solution. With higher contents of
monomers (A2), increasing amounts of resin form an aqueous solution
(and decreasing amounts of resin are in colloidal dispersion form).
As the relative amount of monomers (A2) increases, more of the
water-dilutable hydroxy-functional polyacrylic resin is capable of
dissolution into aqueous solution.
[0030] Water-dilutable hydroxy-functional polyacrylic resins may
have a molecular weight (weight average, as determined by gel
permeation chromatography using polystyrene as standard) of 500 to
100000, or 1000 to 50000; a hydroxyl number of 16.5 to 264 mg
KOH/g, or 33 to 165 mg KOH/g; and an acid number of 5 to 125 mg
KOH/g (based on any acid-based ionic groups or potentially ionic
groups, wherein 25% to 100% are present in ionic salt form).
Water-dilutable hydroxy-functional polyacrylic resins may be in the
form of aqueous solutions and/or dispersions having a solids
content 5% to 90% by weight, 10% to 60% by weight, 10% to 50% by
weight, 20% to 45% by weight, or 20% to 40% by weight; may have a
viscosity at 23.degree. C. of 10 to 100000 mPas, or 100 to 10000
mPas; and may have a pH of 5 to 10, or 6 to 9. Depending upon the
molecular weight of the polyacrylic resins, their content of ionic
groups or potentially ionic groups, and/or any the presence of
emulsifiers, co-solvents, and the like, waterborne systems
comprising the polyacrylic resins may be colloidal dispersions,
molecular solutions, or mixtures of both.
[0031] In various non-limiting embodiments, the polyol resin
component (a) of the aqueous polyurethane coating compositions
disclosed herein may comprise a water-dilutable hydroxy-functional
polyacrylic resin as described in U.S. Pat. No. 4,151,143;
4,888,383; 5,308,912; 5,331,039; 5,552,477; or 6,962,953, which are
incorporated by reference into this specification.
[0032] In various non-limiting embodiments, the polyol resin
component (a) of the aqueous polyurethane coating compositions
disclosed herein may comprise a water-dilutable hydroxy-functional
polyacrylic resin. Suitable water-dilutable hydroxy-functional
resins polyacrylic resins, are commercially available from Bayer
MaterialScience LLC, Pittsburgh, Pa., USA, under the Bayhydrol.RTM.
trademark.
[0033] In various non-limiting embodiments, the aminoplast resin
component (b) of the aqueous polyurethane coating compositions
disclosed herein may be selected from the group consisting of
urea-based resins and melamine-based resins that are
water-dilutable. As used herein, the term "aminoplast resin" refers
to resins based on urea-formaldehyde or melamine-formaldehyde
condensation products. Suitable aminoplast resins are commercially
available from Cytec Surface Specialties Inc., Smyrna, Ga., USA,
under the Cymel.RTM. trademark. Aminoplast resins comprise
functional groups, such as, for example, alkoxymethyl groups, which
are reactive with hydroxyl groups at temperatures above ambient
temperature. For instance, aminoplast resins comprising
alkoxymethyl groups may be used to crosslink and cure polyol resins
primarily by trans-esterifications reaction between the hydroxyl
groups on the polyol resins and the alkoxymethyl groups on the
aminoplast resin.
[0034] As used herein, the term "cured" refers to the condition of
a liquid composition in which an applied film of the composition is
at least set-to-touch as defined in ASTM D 5895--Standard Test
Methods for Evaluating Drying or Curing During Film Formation of
Organic Coatings Using Mechanical Recorder, which is hereby
incorporated by reference into this specification. As used herein,
the terms "cure" and "curing" refer to the progression of an
applied liquid composition from the liquid state to a cured state.
The terms "cured", "cure", and "curing" encompass drying of
compositions through solvent evaporation and chemical crosslinking
of components in compositions.
[0035] In various non-limiting embodiments, the aminoplast resin
component (b) of the aqueous polyurethane coating compositions
disclosed herein may comprise a urea-based resin comprising a
urea-formaldehyde condensation product. Suitable urea-formaldehyde
condensation products include, for example, urea-formaldehyde
condensates that are non-etherified, partially-etherified, or
fully-etherified with monohydric alcohols comprising 1 to 20 carbon
atoms.
[0036] In various non-limiting embodiments, the aminoplast resin
component (b) of the aqueous polyurethane coating compositions may
comprise a melamine-based resin comprising a melamine-formaldehyde
condensation product. Suitable melamine-formaldehyde condensation
products include, for example, melamine-formaldehyde condensates
that are non-etherified, partially-etherified, or fully-etherified
with monohydric alcohols comprising 1 to 20 carbon atoms. In
various non-limiting embodiments, the aminoplast resin component
(b) may comprise monomeric, oligomeric, or polymeric
melamine-formaldehyde resins such as, for example, methylated
melamines, ethylated melamines, propylated melamines, butylated
melamines, and mixed alkylated melamines (e.g.,
methylated/butylated melamines).
[0037] In various non-limiting embodiments, the aminoplast resin
component (b) may comprise methylol groups, alkoxymethyl groups, or
both. An alkoxymethyl group may be of the general formula
--CH.sub.2OR.sup.1, where R.sup.1 is a linear, cyclic, or branched
alkyl chain having from 1 to 20 carbon atoms. In various
non-limiting embodiments, the aminoplast resin component (b) may
comprise an oligomeric, methylated, and high-imino group-containing
melamine-formaldehyde condensate comprising low methylol content.
For example, the aminoplast resin component (b) may comprise an
oligomeric methylated melamine-formaldehyde condensation product
comprising imino groups, methoxymethyl groups, and methylol
groups.
[0038] In various non-limiting embodiments, the
polycarbonate-polyurethane resin component (c) of the aqueous
polyurethane coating compositions disclosed herein may comprise a
water-dilutable polycarbonate-polyurethane resin. As used herein,
the term "polycarbonate-polyurethane resin" refers to oligomeric or
polymeric macromolecules comprising carbonate groups and at least
one of urethane groups or urea groups. Suitable
polycarbonate-polyurethane resins include the aliphatic
polycarbonate-polyurethane resin dispersions in water that are
commercially available from Bayer MaterialScience, LLC, Pittsburgh,
Pa., USA, under the Bayhydrol.RTM. trademark.
[0039] A water-dilutable polycarbonate-polyurethane resin may
comprise a reaction product of: (B1) a polyisocyanate component;
(B2) a polycarbonate polyol component; and (B3) an
isocyanate-reactive component comprising an ionic group or
potentially ionic group.
[0040] In various non-limiting embodiments, the polyisocyanate
component (B1) may comprise a monomeric organic diisocyanate
represented by the formula, R(NCO).sub.2, in which R represents an
organic group. In various non-limiting embodiments, R represents a
divalent aliphatic hydrocarbon group having from 4 to 18 carbon
atoms, a divalent cycloaliphatic hydrocarbon group having from 5 to
15 carbon atoms, a divalent araliphatic hydrocarbon group having
from 7 to 15 carbon atoms, or a divalent aromatic hydrocarbon group
having 6 to 15 carbon atoms.
[0041] Examples of suitable monomeric diisocyanates include, for
example: 1,4-tetra-methylene diisocyanate; 1,6-hexamethylene
diisocyanate; 1-methyl-2,4(2,6)-diisocyanatocyclohexane;
2,2,4-trimethyl-1,6-hexamethylene diisocyanate;
2,4,4-trimethyl-1,6-hexamethylene diisocyanate;
1,12-dodecamethylene diisocyanate; cyclohexane-1,3-diisocyanate;
cyclohexane-1,4-diisocyanate; 1-isocyanato-2-isocyanatomethyl
cyclopentane;
1-isocyanato-3-isocyanatomethyl-3,5,5-trimethyl-cyclohexane
(isophorone diisocyanate), bis-(4-isocyanato-cyclohexyl)-methane;
1,3- and 1,4-bis-(isocyanatomethyl)-cyclohexane;
bis-(4-isocyanatocyclo-hexyl)methane;
2,4'-diisocyanato-dicyclohexyl methane;
bis-(4-isocyanato-3-methyl-cyclohexyl)-methane;
.alpha.,.alpha.,.alpha.',.alpha.'-tetramethyl-1,3- and/or
-1,4-xylylene diisocyanate;
1-isocyanato-1-methyl-4(3)-isocyanatomethyl cyclohexane; 2,4-
and/or 2,6-hexahydro-toluoylene diisocyanate; 1,3- and/or
1,4-phenylene diisocyanate; 2,4- and/or 2,6-toluene diisocyanate;
2,2'-, 2,4'-, and/or 4,4'-diphenylmethane diisocyanate;
naphthalene-1,5-diisocyanate; isomers of any thereof; and
combinations of any thereof.
[0042] In various non-limiting embodiments, the polyisocyanate
component may comprise a monomeric isocyanate comprising three or
more isocyanate groups such as, for example,
4-isocyanatomethyl-1,8-octamethylene diisocyanate. The
polyisocyanate component may comprise polyphenyl polymethylene
polyisocyanates obtained by phosgenating aniline/formaldehyde
condensates. The polyisocyanate component may also comprise
aromatic isocyanates having three or more isocyanate groups, such
as, for example, 4,4',4''-triphenylmethane triisocyanate.
[0043] The polyisocyanate component (B1) may also comprise
diisocyanate adducts and/or oligomers comprising urethane groups,
urea groups, uretdione groups, uretonimine groups, isocyanurate
groups, iminooxadiazine dione groups, oxadiazine trione groups,
carbodiimide groups, acyl urea groups, biuret groups, and/or
allophanate groups. For example, the polyisocyanate component may
include:
(1) Isocyanurate group-containing polyisocyanates that may be
prepared as set forth in DE-PS 2,616,416; EP-OS 3,765; EP-OS
10,589; EP-OS 47,452; U.S. Pat. No. 4,288,586; and U.S. Pat. No.
4,324,879, which are incorporated by reference into this
specification; (2) Uretdione diisocyanates that may be prepared by
oligomerizing a portion of the isocyanate groups of a diisocyanate
in the presence of a suitable catalyst, e.g., a trialkyl phosphine
catalyst, and which may optionally be used in admixture with other
isocyanates, particularly the isocyanurate group-containing
polyisocyanates set forth under (1) above; (3) Biuret
group-containing polyisocyanates that may be prepared according to
the processes disclosed in U.S. Pat. Nos. 3,124,605; 3,358,010;
3,644,490; 3,862,973; 3,906,126; 3,903,127; 4,051,165; 4,147,714;
and 4,220,749, which are incorporated by reference into this
specification, by using co-reactants such as water, tertiary
alcohols, primary and secondary monoamines, and primary and/or
secondary diamines; (4) Iminooxadiazine dione and, optionally,
isocyanurate group-containing polyisocyanates, that may be prepared
in the presence of fluorine-containing catalysts as described in
DE-A 19611849, which is incorporated by reference into this
specification; (5) Carbodiimide group-containing polyisocyanates
that may be prepared by oligomerizing diisocyanates in the presence
of carbodiimidization catalysts as described in DE-PS 1,092,007;
U.S. Pat. No. 3,152,162; and DE-OS 2,504,400, DE-OS 2,537,685, and
DE-OS 2,552,350, which are incorporated by reference into this
specification; and (6) Polyisocyanates containing oxadiazinetrione
groups, e.g., the reaction product of two moles of a diisocyanate
and one mole of carbon dioxide.
[0044] Polyisocyanate components (B1) comprising diisocyanate
adducts and/or oligomers may have an average isocyanate group
functionality of 2 to 6 or 2 to 4, for example. Polyisocyanate
components (B1) comprising diisocyanate adducts and oligomers may
have an average isocyanate (NCO) content of 5% to 30%, 10% to 25%,
or 15% to 25%, by weight of the component.
[0045] In various non-limiting embodiments, the polyisocyanate
component (B1) may be a monomeric (cyclo)aliphatic diisocyanate
such as, for example, a diisocyanate selected from the group
consisting of 1,6-hexamethylene diisocyanate (HDI);
1-isocyanato-3-isocyanatomethyl-3,5,5-trimethyl-cyclohexane
(isophorone diisocyanate or IPDI);
4,4'-diisocyanatodicyclohexylmethane (H.sub.12MDI);
1-methyl-2,4(2,6)-diisocyanatocyclohexane; isomers of any thereof;
and combinations of any thereof. For example, in various
non-limiting embodiments, H.sub.12MDI may be used to produce (c)
water-dilutable polycarbonate-polyurethane resin. In various
non-limiting embodiments, the polyisocyanate component (B1) may
comprise 50 to 100 weight percent of aliphatic diisocyanate and 0
to 50 weight percent of other aliphatic polyisocyanates having a
molecular weight of 140 to 1500, such as, for example, diisocyanate
adduct and/or oligomer.
[0046] In various non-limiting embodiments, a polyisocyanate
component (B1) may comprise at least one of HDI, IPDI, H.sub.12MDI,
1-methyl-2,4(2,6)-diisocyanatocyclohexane, and/or adducts of these
diisocyanates comprising isocyanurate, uretdione, biuret, and/or
iminooxadiazine dione groups as described above.
[0047] In various non-limiting embodiments, a polycarbonate polyol
component (B2) may comprise a polycondensation reaction product of
polyhydric alcohols and phosgene or a polycondensation reaction
product of polyhydric alcohols and diesters of carbonic acid.
Suitable polyhydric alcohols include, for example, diols such as
1,3-propanediol; ethylene glycol; propylene glycol;
1,4-propanediol; diethylene glycol; triethylene glycol;
tetraethylene glycol; 1,4-butanediol; 1,6-hexanediol;
trimethylenepentanediol; 1,4-cyclohexanediol;
1,4-cyclohexanedimethanol; neopentyl glycol; 1,8-octanediol; and
combinations of any thereof. Suitable polyhydric alcohols also
include, for example, tri-functional and multi-functional hydroxyl
compounds such as glycerol; trimethylolpropane; trimethylolethane;
hexanetriol isomers; pentaerythritol; and combinations of any
thereof. Tri-functional and multi-functional hydroxyl compounds may
be used to produce a polycarbonate polyol having a branched
structure.
[0048] A polycarbonate polyol may have an average hydroxyl
functionality of 1 to 5, or any sub-range therein, such as, for
example, 1 to 2, 1.5 to 2.5, 1.2 to 2.2, or 1.8 to 2.2. A
polycarbonate polyol may have an average molecular weight of 300 to
10000 or any sub-range therein, such as, for example, 300 to 5000,
1000 to 8000, 1000 to 6000, 2000 to 6000, 500 to 6000, 500 to 3000,
or 1000 to 3000. A polycarbonate polyol may have an OH number of 25
to 350 mg KOH/g solids.
[0049] In various non-limiting embodiments, an isocyanate-reactive
component (B3) comprising an ionic group or potentially ionic group
may comprise an ionic group or potentially ionic group may at least
partially impart water-dilutability (e.g., aqueous solubility or
aqueous dispersability) to water-dilutable
polycarbonate-polyurethane resins by covalently incorporating into
the macromolecules, increasing the hydrophilicity of the
macromolecules. The isocyanate-reactive component (B3) may comprise
at least one ionic group or potentially ionic group, which may be
either cationic or anionic in nature. The isocyanate-reactive
component (B3) may also comprise at least one isocyanate-reactive
group such as for example, a hydroxyl group and/or an amine group.
The isocyanate-reactive functionality of the isocyanate-reactive
component (B3) and the hydroxyl functionality of the polycarbonate
polyol component (B2) may react with the isocyanate functionality
of the polyisocyanate component (B1) to, at least in part, produce
a water-dilutable polycarbonate-polyurethane resin.
[0050] Cationic and anionic isocyanate-reactive components (B3)
include compounds comprising, for example, sulfonium groups,
ammonium groups, phosphonium groups, carboxylate groups, sulfonate
groups, phosphonate groups, or the corresponding non-ionic acid
groups (i.e., potentially ionic groups) that can be converted by
deprotonation (i.e., salt formation) into these groups.
[0051] Suitable isocyanate-reactive components (B3) include, for
example, mono-hydroxycarboxylic acids; di-hydroxycarboxylic acids;
mono-aminocarboxylic acids; di-aminocarboxylic acids;
mono-hydroxysulfonic acids; di-hydroxysulfonic acids;
mono-aminosulfonic acids; di-aminosulfonic acids;
mono-hydroxyphosphonic; di-hydroxyphosphonic acids;
mono-aminophosphonic acids; di-aminophosphonic acids; their ionic
salts; and combinations of any thereof.
[0052] Suitable isocyanate-reactive components (B3) include, for
example, dimethylolpropionic acid; dimethylolbutyric acid;
hydroxypivalic acid; N-(2-aminoethyl)-.beta.-alanine;
ethylenediame-propyl- or butyl-sulfonic acid; 1,2- or
1,3-propylenediamine-.beta.-ethylsulfonic acid; citric acid;
glycolic acid; lactic acid; 2-aminoethylaminoethanesulfonic acid;
glycine; alanine; taurine; lysine; 3,5-diaminobenzoic acid; an
adduct of isophorone diisocyanate (IPDI) and acrylic acid (see,
e.g., European Patent No. 916,647) and its alkali metal and/or
ammonium salts; an adduct of sodium bisulfite with
but-2-ene-1,4-diol; polyethersulfonate; and the propoxylated adduct
of 2-butenediol and NaHSO.sub.3 (see, e.g., German Patent No.
2,446,440).
[0053] Likewise, suitable isocyanate-reactive components (B3)
include, for example, other 2,2-bis(hydroxymethyl)alkane-carboxylic
acids such as dimethylolacetic acid and 2,2-dimethylolpentanoic
acid. In addition, suitable isocyanate-reactive components (B3)
include dihydroxysuccinic acid, Michael adducts of acrylic acid
with amines such as isophoronediamine or hexamethylenediamine, or
mixtures of such acids and/or dimethylolpropionic acid and/or
hydroxypivalic acid. Further, suitable isocyanate-reactive
components (B3) include sulfonic acid diols optionally comprising
ether groups, for example, the compounds described in U.S. Pat. No.
4,108,814, which is incorporated by reference into this
specification.
[0054] In various non-limiting embodiments, the
water-polycarbonate-polyurethane resin comprises a reaction product
of components (B1), (B2), and an isocyanate-reactive component (B3)
possessing carboxyl or carboxylate groups, sulfonic acid or
sulfonate groups, and/or ammonium groups. The isocyanate-reactive
component (B3) may be incorporated into water-dilatable
polycarbonate-polyurethane resin macromolecules by urethane-forming
and/or urea-forming reactions between the isocyanate-reactive
groups and the isocyanate groups of the polyisocyanate component
(B1).
[0055] In various non-limiting embodiments, an optional
isocyanate-reactive component (B4) may comprise, for example, chain
extenders and/or chain terminators. A chain-extending and/or
chain-terminating component may comprise an ionic group or
potentially ionic group and at least one group that is reactive
with isocyanate groups in an addition reaction. Examples of
chain-extending components include, for example, methyleriediamine;
[0056] ethylenediamine; propylenediamine; 1,4-butylenediamine;
1,6-hexamethylenediamine; 2-methyl-1,5-pentanediamine (Dytek-A from
DuPont); 1-amino-3,3,5-trimethyl-5-aminomethyl cyclohexane
(isophorone diamine); piperazine; 1,4-diaminocyclohexane;
bis(4-aminocyclohexyl)methane; adipic acid dihydrazide; alkylene
oxide diamines; dipropylamine diethyleneglycol;
N-(2-aminoethyl)-2-aminoethane sulfonic acid (or salt thereof);
N-(2-aminoethyl)-2-aminopropionic acid (or salt thereof); and
combinations of any thereof.
[0057] Examples of chain-terminating components include, for
example, compounds having the formula:
##STR00001##
wherein R.sub.1 is a hydrogen atom or alkyl radical, optionally
having a hydroxyl end and R.sub.2 is an alkyl radical, optionally
having a hydroxyl end. Suitable chain-terminating compounds include
compounds such as monoamines or monoalcohols. Examples include, but
are not limited to, methylamine; ethylamine; propylamine;
butylamine; octylamine; laurylamine; stearylamine;
isononyloxy-propylamine; dimethylamine; diethylamine;
dipropylamine; dibutylamine; N-methylaminopropylamine;
diethyl(methyl)aminopropylamine; morpholine; piperidine;
diethanolamine; and combinations of any thereof. Also suitable are
chain terminating alcohols, such as, for example, C.sub.1-C.sub.10
or higher alcohols including, methanol, butanol, hexanol,
2-ethylhexyl alcohol, isodecyl alcohol, and the like, and mixtures
thereof, as well as amino-alcohols, such as, for example,
aminomethylpropanol (AMP).
[0058] A water-dilutable polycarbonate-polyurethane resin may be
prepared by reacting components (B1) through (B4) using an acetone
process or modification thereof. A description of suitable
processes may be found, for example, in Methoden der Organischen
Chemie, Houben-Weyl, 4th Edition, Volume E20/Part 2, p. 1682, Georg
Thieme Verlag, Stuttgart, 1987, which is incorporated by reference
into this specification.
[0059] A non-limiting example of an acetone process is described
below. In a first stage an adduct comprising unreacted isocyanate
groups is synthesized from a polyisocyanate component (B1), a
polycarbonate polyol component (B2), and an isocyanate-reactive
component (B3) comprising an ionic group or potentially ionic
group. In a second stage, the adduct is dissolved in an organic, at
least partially water-miscible, solvent comprising no
isocyanate-reactive groups. Suitable solvents include acetone;
methylethyl ketone (MEK); 2-butanone; tetrahydrofuran; dioxin; and
combinations of any thereof. In a third stage, the unreacted
isocyanate-containing adduct solution is reacted with mixtures of
amino-functional chain-extenders and/or chain-terminators. An
amino-functional chain-extender may comprise a sulfonic acid group
or carboxyl group (in either nonionic acid form or ionic salt
form). In a fourth stage, the water-dilutable
polycarbonate-polyurethane resin product is dispersed in the form
of a fine-particle dispersion by addition of water to the organic
solution or by addition of the organic solution to water. In a
fifth stage, the organic solvent is partially or wholly removed by
distillation, optionally under reduced pressure.
[0060] A water-dilutable polycarbonate-polyurethane resin may be
characterized by a glass transition temperature of between
-60.degree. C. and 0.degree. C., such as, for example, between
-40.degree. C. and -20.degree. C. A dispersion of a water-dilutable
polycarbonate-polyurethane resin may have a viscosity at 25.degree.
C. of less than 1000 mPas or less than 500 mPas, for example,
between 50 and 1000 mPas or 50 and 500 mPas. A water-dilutable
polycarbonate-polyurethane resin may have a number average
molecular weight range of 500 to 6000.
[0061] In various non-limiting embodiments, the one-component
thermally-curable aqueous polyurethane coating compositions
disclosed herein may be formulated by blending a polyol resin
component (a); an aminoplast resin component (b), and a
polycarbonate-polyurethane resin component (c). Polyol resin
component (a) and aminoplast resin component (b) may be utilized in
amounts such that an equivalent ratio of the alkoxymethyl groups of
the aminoplast resin component (b) to the hydroxyl groups of the
polyol resin component (a) is at least 0.05:1, for example from
0.05:1 to 20:1.
[0062] In various non-limiting embodiments, the
polycarbonate-polyurethane resin component (c) is non-functional.
As used herein, the term "non-functional," with respect to a
chemical component of the one-component thermally-curable aqueous
polyurethane coating compositions disclosed herein, refers to a
substantial lack of chemical reactivity with polyol resin
components (a) and aminoplast resin components (b). For example, a
non-functional polycarbonate-polyurethane resin component (c) does
not chemically react with components (a) and/or (b) of the coating
composition during thermal curing. In this manner, a non-functional
polycarbonate-polyurethane resin component (c) is substantially
free of unreacted isocyanate groups, unreacted hydroxyl groups,
isocyanate-reactive groups, hydroxyl-reactive groups, and other
functional groups that may be reactive with any functional groups
comprising polyol resin components (a) and aminoplast resin
components (b).
[0063] The one-component thermally-curable aqueous polyurethane
coating compositions disclosed herein may be produced by blending
water-dilutable polyol resin component (a), water-dilutable
aminoplast resin component (b), and water-dilutable
polycarbonate-polyurethane resin component (c). These components
may be blended in aqueous dispersion, aqueous solution, or a
combination of aqueous dispersion and aqueous solution, optionally
with emulsifiers, dispersants, surfactants, co-solvents, and/or the
like. For instance, water-dilutable polyol resin component (a),
water-dilutable aminoplast resin component (b), and water-dilutable
polycarbonate-polyurethane resin component (c) may be provided as
separate aqueous dispersions, aqueous solutions, and/or
dispersion/solutions in water-miscible solvents, which are combined
together to create an aqueous mixture of components (a), (b), and
(c). It is also possible to mix any combination of the components
(a), (b), and/or (c) in anhydrous form, or as a solution/dispersion
in a non-aqueous water-miscible solvent, and then disperse the
mixture of components (a), (b), and/or (c) in water.
[0064] One-component thermally-curable aqueous polyurethane coating
compositions comprising a polyol resin component (a); an aminoplast
resin component (b); and a polycarbonate-polyurethane resin
component (c) may be characterized by a blended binder in which
components (a) and (b) mutually react during curing to crosslink
the resins, but component (c) is non-functional (i.e.,
non-reactive) with components (a) and (b), and therefore, creates
an interpenetrating non-crosslinked polymer network with respect to
the crosslinked polymer network comprising a reaction product of
components (a) and (b).
[0065] In various non-limiting embodiments, the one-component
thermally-curable aqueous polyurethane coating compositions
described herein may comprise 1% to 99% by weight, preferably 40%
to 90% by weight, most preferably 60% to 80% by weight on a solids
basis of a water-dilutable hydroxy-functional polyacrylic resin;
and a water-dilutable aminoplast resin; and 99% to 1% by weight,
preferably 60% to 10% by weight, most preferably 40% to 20% by
weight on a solids basis of a water-dilutable non-functional
polycarbonate-polyurethane resin.
[0066] In various non-limiting embodiments, the weight ratio on a
solids basis of the polyol resin component (a) to the aminoplast
resin component (b) may be from 55:45 to 85:15. In various
non-limiting embodiments, the weight ratio on a solids basis of the
polyol resin component (a) to the aminoplast resin component (b)
may be from 60:40 to 70:30.
[0067] In various non-limiting embodiments, one-component
thermally-curable aqueous polyurethane coating compositions
comprising a polyol resin component (a); an aminoplast resin
component (b); and a polycarbonate-polyurethane resin component (c)
may comprise optional components such as, for example, additional
water-dilutable resin components based on polymeric polyols.
Additional water-dilutable resin components based on polymeric
polyols may include, for example, polyether polyols, polyester
polyols, polyepoxide polyols, polylactone polyols, polyacrylate
polyols, polycarbonate polyols, and combinations of any thereof.
Additional water-dilutable resin components may be formulated in
admixture in aqueous solution and/or aqueous dispersion with the
resin components (a), (b), and (c).
[0068] In various non-limiting embodiments, one-component
thermally-curable aqueous polyurethane coating compositions
comprising a polyol resin component (a); an aminoplast resin
component (b); and a polycarbonate-polyurethane resin component (c)
may be dried and/or thermally cured by any suitable means known to
those skilled in the art such as, for example, air drying,
accelerated drying by exposure to heat, and thermal curing by
exposure to heat. For example, in various non-limiting embodiments,
one-component thermally-curable aqueous polyurethane coating
compositions comprising a polyol resin component (a); an aminoplast
resin component (b); and a polycarbonate-polyurethane resin
component (c) may be thermally cured by exposure to temperatures of
100.degree. C. to 250.degree. C. for 15 minutes to 60 minutes. The
energy needed to cure the system can come from any source known to
those skilled in the art including, but not limited to conventional
convection ovens, infrared heat sources, microwaves, electron
beams, or combination thereof.
[0069] The one-component thermally-curable aqueous polyurethane
coating compositions disclosed herein may produce cured coating
films that exhibit microhardness values of no greater than 90
N/mm.sup.2 (Martens/Universal Hardness). In various non-limiting
embodiments, the one-component thermally-curable aqueous
polyurethane coating compositions disclosed herein may produce
cured coating films that exhibit microhardness values of no greater
than 75 N/mm.sup.2, 65 N/mm.sup.2, 55 N/mm.sup.2, 50 N/mm.sup.2, 45
N/mm.sup.2, 35 N/mm.sup.2, 25 N/mm.sup.2, 20 N/mm.sup.2, or 15
N/mm.sup.2.
[0070] In various non-limiting embodiments, the one-component
thermally-curable aqueous polyurethane coating compositions
disclosed herein may produce cured coating films that exhibit
impact strength values of at least 20 in-lbs (direct and/or
reverse, determined according to ASTM D2794-93 (2010): Standard
Test Method for Resistance of Organic Coatings to the Effects of
Rapid Deformation (Impact), which is incorporated by reference into
this specification). In various non-limiting embodiments, the
one-component thermally-curable aqueous polyurethane coating
compositions disclosed herein may produce cured coating films that
exhibit impact strength values of at least 120 in-lbs, 140 in-lbs,
or 160 in-lbs.
[0071] In various non-limiting embodiments, the one-component
thermally-curable aqueous polyurethane coating compositions
disclosed herein may also comprise silane-functional adhesion
promoters such as, for example, the adhesion promoters disclosed in
U.S. Pat. No. 6,403,175, which is incorporated by reference into
this specification. Suitable adhesion promoters include, for
example, .gamma.-mercaptopropyltrimethoxysilane;
3-aminopropyltriethoxysilane; 3-aminopropylsilane hydrolysate;
3-glycidyloxypropyltriethoxysilane; and combinations of any
thereof.
[0072] The one-component thermally-curable aqueous polyurethane
coating compositions disclosed herein may be applied to substrates
using any suitable methods, such as, for example, spraying; knife
coating; curtain coating; vacuum coating; rolling; pouring;
dipping; spin coating; squeegeeing; brushing; squirting; screen
printing; gravure printing; flexographic printing; or offset
printing. Suitable substrates include, for example, glass; wood;
metal; paper; leather; textiles; felt, concrete; masonry; ceramic;
stone; and plastics such as, for example, moldings and films of
ABS, AMMA, ASA, CA, CAB, EP, UF, CF, MF, MPF, PF, PAN, PA, PE,
HDPE, LDPE, LLDPE, UHMWPE, PET, PMMA, PP, PS, SB, PUR, PVC, RF,
SAN, PBT, PPE, POM, PUR-RIM, SMC, BMC, PP-EPDM, and UP
(abbreviations according to DIN 7728T1). The one-component
thermally-curable aqueous polyurethane coating compositions
disclosed herein may be applied to substrates comprising
combinations of the above materials. The one-component
thermally-curable aqueous polyurethane coating compositions
disclosed herein may also be applied as undercoatings or
overcoatings with other coatings. The one-component
thermally-curable aqueous polyurethane coating compositions
disclosed herein may also be applied to a temporary substrate
support, dried and/or cured partly or fully, and detached from the
substrate support to produce free films, for example.
[0073] In various non-limiting embodiments, the one-component
thermally-curable aqueous polyurethane coating compositions
disclosed herein may be especially suitable for glass substrates,
such as, for example, flat glass, glass panels, and glass
containers such as glass jars or glass bottles. Further, the
one-component thermally-curable aqueous polyurethane coating
compositions disclosed herein provide marring resistance and
durability, which may be advantageous, for example, during glass
container filling operations. Glass substrates comprising the
one-component thermally-curable aqueous polyurethane coating
compositions disclosed herein may be characterized by good hand
feel. The one-component thermally-curable aqueous polyurethane
coating compositions disclosed herein may be applied to glass
substrates with or without hot end coating, with or without cold
end coating, or both; and with or without a silane pre-treatment of
the glass substrates.
[0074] The one-component thermally-curable aqueous polyurethane
coating compositions disclosed herein may provide design freedom to
manufacture transparent, pigmented, high gloss, matte, and frosted
looks on glass substrates. Suitable representative pigments that
may be formulated into the one-component thermally-curable aqueous
polyurethane coating compositions disclosed herein include, for
example, rutile and anatase titanium dioxide, yellow and red iron
oxides, green and blue copper phthalocyanine, carbon blacks,
leafing and nonleafing aluminum, barium sulfate, calcium carbonate,
sodium silicate, magnesium silicate, zinc oxide, antimony oxide,
di-arylide yellow, monoarylide yellow, nickel arylide yellow,
benzimidazolone oranges, naphthol reds, quinacridone reds,
pearlescent pigments (e.g., mica platelets), bronze platelets,
nickel platelets, stainless steel platelets, micronized matting
agents (e.g., methylenediaminomethylether-polycondensate), and
combinations of any thereof.
[0075] The one-component thermally-curable aqueous polyurethane
coating compositions disclosed herein may be applied over a label
(e.g. pressure-sensitive labels, UV-activated labels, heat transfer
labels, and the like) or over a decorative organic and/or inorganic
coating that has previously been applied to a glass substrate.
Suitable decorative organic coatings that may be used with the
one-component thermally-curable aqueous polyurethane coating
compositions disclosed herein include, for example, EcoBrite
Organic Ink (PPG Industries, Inc., Pittsburgh, Pa., USA) and
SpecTruLite (Ferro Corporation, Cleveland, Ohio, USA).
[0076] A primer treatment may be applied to a glass substrate
before application of a one-component thermally-curable aqueous
polyurethane coating composition as disclosed herein. The primer
treatment may be any coating that provides lubrication to protect a
glass substrate between the time of manufacture and the time of
application of the coating and/or improves the adhesion of the
coating to the glass substrate. A primer treatment may comprise
both a hot end coating and a cold end coating. A glass substrate
may not have a hot end coating, such that a primer treatment
comprises a cold end coating applied only after the substrate has
been substantially cooled. A primer treatment may comprise a cold
end coating, the cold end coating comprising a diluted silane
composition or mixture of a silane composition and a
surface-treatment composition. Any silane composition suitable for
use as a primer on a glass substrate may be used in a primer
coating, non-limiting examples of which include monoalkoxy-silanes,
dialkoxysilanes, trialkoxysilanes, and tetralkoxysilanes.
[0077] A surface-treatment composition may comprise polyethylene
compositions, stearate compositions, or mixtures thereof, which do
not require removal before the application of further coatings to
the glass substrates. Stearate compositions may comprise the salts
and esters of stearic acid (octadecanoic acid), such as, for
example, a T5 stearate coating (Tegoglas, Arkema, Philadelphia,
Pa., USA). A primer coating may be in the form of an aqueous
solution, dispersion, or emulsion. For example, a surface-treatment
composition may comprise a polyethylene emulsion such as Duracote,
Sun Chemical. A primer treatment also may comprise additional
compositions to improve subsequently applied coatings, non-limiting
examples of which include surfactants and lubricants.
[0078] In various non-limiting embodiments, the one-component
thermally-curable aqueous polyurethane coating compositions
disclosed herein may function as a primer coating and a topcoating,
providing sufficient lubricity, mar resistance, and toughness for
line processing of glass containers.
[0079] The non-limiting and non-exhaustive examples that follow are
intended to further describe various non-limiting and
non-exhaustive embodiments without restricting the scope of the
embodiments described in this specification. In the following
examples, all parts and percentages are by weight, unless otherwise
indicated.
EXAMPLES
[0080] One-component thermally-curable aqueous polyurethane coating
compositions comprising a polyacrylic polyol resin, an aminoplast
resin, and a polycarbonate-polyurethane resin were prepared as
follows. Aqueous dispersions of a hydroxy-functional polyacrylic
resin (Bayhydrol.RTM. A XP 2770, Bayer MaterialScience LLC,
Pittsburgh, Pa., USA) were mixed with Cymel.RTM. 327 and
Bayhydrol.RTM. XP 2637. Bayhydrol.RTM. A XP 2770 is a polyacrylic
resin provided as an aqueous dispersion of approximately 45% solids
having 3.9% hydroxyl content on a solids weight basis.
[0081] Dipropylene glycol, .gamma.-mercaptopropyltrimethoxysilane
(Silquest.RTM. A-189, Momentive Performance Materials, Albany,
N.Y., USA), and 3-aminopropyl-triethoxysilane (Dynasylan.RTM. AMEO,
Evonik Corporation, Parsippany, N.J., USA) were added with
continuous stirring to the aqueous mixtures of the
hydroxy-functional polyacrylic resin, the aminoplast resin, and the
polycarbonate-polyurethane resin. The resulting mixtures were
agitated using a mechanical mixer until homogeneous mixtures were
obtained. The homogeneous mixtures were deaerated and stored
overnight before use. The mixtures were prepared according to the
formulations provided in Table 1 (parts by weight, solvent weight
included).
TABLE-US-00001 TABLE 1 Components A B C D E F G H I J Formulations
polyacrylic resin dispersion 71.84 53.88 82.42 72.02 61.72 49.38
32.92 90.86 68.15 0 aminoplast resin 26.16 19.62 15.58 13.73 11.78
9.42 6.28 7.14 5.36 14.70 polycarbonate-polyurethane 0 24.5 0 12.25
24.5 39.2 58.8 0 24.5 83.3 resin dispersion dipropylene glycol 1.6
1.6 1.6 1.6 1.6 1.6 1.6 1.6 1.6 1.6 .gamma.- 0.2 0.2 0.2 0.2 0.2
0.2 0.2 0.2 0.2 0.2 mercaptopropyltrimethoxysilane
3-aminopropyl-triethoxysilane 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2
0.2 Binder Resin Component Weight Ratios polyacrylic
resin/aminoplast 55/45 55/45 70/30 70/30 70/30 70/30 70/30 85/15
85/15 0/100 resin (wt/wt on solids) Coating Properties Direct
Impact (in-lbs) 20 160 20 60 160 160 160 20 160 160 Reverse Impact
(in-lbs) <20 160 <20 20 160 160 160 <20 160 160
Microhardness (N/mm.sup.2) 64 34 139 87 51 18 13 152 64 1 Scribe
adhesion Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass
[0082] The one-component thermally-curable aqueous polyurethane
coating compositions were tested for impact resistance,
microhardness, and adhesion. Coatings for impact resistance testing
were applied onto Bonderite B1000 cold rolled steel panels using a
number 50 wire wound rod. Coatings for microhardness testing were
applied onto glass disks using an Eppendorf pipettor (80
microliters) and spread over the disks using the pipettor tip.
Coatings for adhesion testing were applied onto the airside of
4-inch by 4-inch glass Taber panels using a number 50 wire wound
rod.
[0083] The applied coatings were cured at 170.degree. C. for 30
minutes in an oven. The coatings applied to the glass disks for
microhardness testing were allowed to air-dry under ambient
conditions for about 120 minutes before the oven cure. All testing
was performed at least 24 hours after the applied coatings and
substrates were removed from the oven. The film thicknesses of the
cured coatings on the steel panels were measured using a
Fischerscope MMS instrument according to ASTM D1186-93: Standard
Test Methods for Nondestructive Measurement of Dry Film Thickness
of Nonmagnetic Coatings Applied to a Ferrous Base, which is
incorporated by reference into this specification. The film
thicknesses were in the range of 0.75 to 2.25 mils.
[0084] Impact resistance testing was performed according to ASTM
D2794-93 (2010): Standard Test Method for Resistance of Organic
Coatings to the Effects of Rapid Deformation (Impact), which is
incorporated by reference into this specification. Microhardness
(Martens/Universal Hardness) testing was performed on a
Fischerscope H100C instrument. Adhesion testing was performed
according to ASTM D4060-95: Standard Test Method for Abrasion
Resistance of Organic Coatings by the Taber Abraser, which is
incorporated by reference into this specification. Scribe adhesion
testing was performed on glass Taber panels. Two one-inch long
scribes diagonal to each other were cut using a utility knife and
the adhesion of the film to glass was inspected visually. If no
film peeled from the substrate, the coating was marked as
"pass."
[0085] The results of the impact resistance testing, microhardness
testing, and scribe adhesion testing are presented in Table 1. The
addition of non-functional polycarbonate-polyurethane resin
improved the flexibility, and toughness of the coatings, as shown
by the decrease in microhardness and/or the increase in direct
and/or reverse impact strength. Further, addition of non-functional
polycarbonate-polyurethane resin did not have a negative affect on
adhesion. For instance, formulations A, C, and H did not contain
any polycarbonate-polyurethane resin, but formulations B, D, and I
contained additions of approximately 25% of the
polycarbonate-polyurethane resin dispersion (10% on a solids
basis), relative to formulations A, C, and H, respectively.
Comparisons of formulations A and B, formulations C and D, and
formulations H and I, shows that the addition of the non-functional
polycarbonate-polyurethane resin generally decreased the hardness
and increased the impact strength of the cured coating films.
[0086] Further, formulations C, D, E, F, and G all had the same
weight ratio of hydroxy-functional polyacrylic resin to aminoplast
resin. Formulation C was free of non-functional
polycarbonate-polyurethane resin, and formulations D though G had
increasing non-functional polycarbonate-polyurethane resin content,
i.e., 12% dispersion (5% solids), 25% dispersion (10% solids), 40%
dispersion, (16% solids), and 60% dispersion, (24% solids),
respectively. A comparison of formulation C with formulations D
though G shows that increasing the content of non-functional
polycarbonate-polyurethane resin decreases hardness while
increasing impact strength and toughness, and maintaining good
substrate adhesion.
[0087] As shown in the above examples, the one-component
thermally-curable aqueous polyurethane coating compositions
disclosed herein exhibit low hardness, high impact resistance, high
toughness, high abrasion resistance, good adhesion to glass
substrates, while being free of blocking agents and comprising
aminoplast resins. These results are significant and unexpected
because, generally, aminoplast resins produce relatively hard cured
coating films when used to crosslink polyol resins. As such, the
one-component thermally-curable aqueous polyurethane coating
compositions disclosed herein facilitate the use of aminoplast
crosslinking resins without undesirable coating properties such as,
for example, increased brittleness, decreased impact resistance and
toughness. Therefore, the one-component thermally-curable aqueous
polyurethane coating compositions disclosed herein are particularly
advantageous for substrates such as, for example, glass materials,
which may readily show mechanical surface damage of relatively hard
and brittle coating films on the substrate.
[0088] In various non-limiting embodiments, the one-component
thermally-curable aqueous polyurethane coating compositions
disclosed herein may be used to coat glass containers such as, for
example, glass bottles and glass jars. The improved coating
properties exhibited by the one-component thermally-curable aqueous
polyurethane coating compositions disclosed herein (e.g., low
hardness, high impact resistance, high toughness, and good adhesion
to glass substrates) are particularly advantageous in glass
container manufacturing operations where the containers may undergo
significant scuffing and/or marring as the containers are handled
by machinery in line operations and experience line pressure. The
one-component thermally-curable aqueous polyurethane coating
compositions disclosed herein provide surface coatings that are
capable of withstanding and absorbing impact pressures during line
operations with minimal or zero surface scuffing, or marring.
[0089] This specification has been written with reference to
various non-limiting and non-exhaustive embodiments. However, it
will be recognized by persons having ordinary skill in the art that
various substitutions, modifications, or combinations of any of the
disclosed embodiments (or portions thereof) may be made within the
scope of this specification. Thus, it is contemplated and
understood that this specification supports additional embodiments
not expressly set forth herein. Such embodiments may be obtained,
for example, by combining, modifying, or reorganizing any of the
disclosed steps, components, elements, features, aspects,
characteristics, limitations, and the like, of the various
non-limiting embodiments described in this specification. In this
manner, Applicant reserves the right to amend the claims during
prosecution to add features as variously described in this
specification, and such amendments comply with the requirements of
35 U.S.C. .sctn.112, first paragraph, and 35 U.S.C.
.sctn.132(a).
* * * * *