U.S. patent application number 13/176915 was filed with the patent office on 2013-01-10 for waterborne polyurethane coating compositions.
This patent application is currently assigned to Bayer MaterialScience AG. Invention is credited to Abduallah Ekin, Torsten Pohl, Raymond Stewart, Ramesh Subramanian.
Application Number | 20130011592 13/176915 |
Document ID | / |
Family ID | 47437669 |
Filed Date | 2013-01-10 |
United States Patent
Application |
20130011592 |
Kind Code |
A1 |
Subramanian; Ramesh ; 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 polyester polyol component.
Inventors: |
Subramanian; Ramesh;
(Coraopolis, PA) ; Stewart; Raymond; (Lawrence,
PA) ; Ekin; Abduallah; (Imperial, PA) ; Pohl;
Torsten; (Leverkusen, DE) |
Assignee: |
Bayer MaterialScience AG
Leverkusen
PA
Bayer MaterialScience LLC
Pittsburgh
|
Family ID: |
47437669 |
Appl. No.: |
13/176915 |
Filed: |
July 6, 2011 |
Current U.S.
Class: |
428/34.7 ;
428/425.6; 524/188; 524/262; 524/265; 524/537 |
Current CPC
Class: |
Y10T 428/131 20150115;
Y10T 428/1317 20150115; C03C 17/322 20130101; C09D 167/02 20130101;
C08G 18/409 20130101; Y10T 428/1321 20150115; C09D 167/02 20130101;
C09D 175/06 20130101; C08G 18/0866 20130101; C08G 18/44 20130101;
C08L 61/28 20130101; C08L 61/28 20130101; Y10T 428/31601 20150401;
C08L 75/04 20130101 |
Class at
Publication: |
428/34.7 ;
524/537; 524/188; 524/262; 524/265; 428/425.6 |
International
Class: |
C09D 175/06 20060101
C09D175/06; B32B 17/10 20060101 B32B017/10; C08K 5/5435 20060101
C08K005/5435; C09D 161/28 20060101 C09D161/28; C08K 5/544 20060101
C08K005/544; C08K 5/548 20060101 C08K005/548 |
Claims
1. An aqueous polyurethane coating composition comprising: (a) a
water-dilutable hydroxy-functional polyester resin; (b) a
water-dilutable aminoplast resin; and (c) a water-dilutable
polycarbonate-polyurethane resin, wherein the aqueous polyurethane
coating composition comprises (i) 50% to 99% by weight, on a solids
basis of the water-dilutable hydroxy-functional polyester resin and
a water-dilutable aminoplast resin; and (ii) 50% to 1% by weight on
a solids basis of the water-dilutable polycarbonate-polyurethane
resin, the weight percents totaling 100%; and wherein the weight
ratio on a solids basis of the hydroxy-functional polyester resin
to the aminoplast resin is from 50:50 to 90:10; and wherein the
polycarbonate-polyurethane resin is non-functional.
2. The aqueous polyurethane coating composition of claim 1, wherein
the hydroxy-functional polyester 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: 60% to 75% by weight on a solids basis of the
water-dilutable hydroxy-functional polyester resin; a
water-dilutable aminoplast resin; and 40% to 25% 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 1,
wherein the weight ratio on a solids basis of the
hydroxy-functional polyester resin to the aminoplast resin is from
50:50 to 90:10.
12. The aqueous polyurethane coating composition of claim 1,
further comprising a silane-functional adhesion promoter.
13. The aqueous polyurethane coating composition of claim 12,
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.
14. The aqueous Polyurethane coating composition of claim 1,
further comprising a an additional polyol resin selected from the
group consisting of water-dispersible hydroxy-functional
polyether-polyurethane resins and water-dispersible
hydroxy-functional polyacrylic resins.
15. A substrate at least partially coated with the coating
composition of claim 1.
16. The substrate of claim 15, wherein the coating exhibits
microhardness of no greater than 90 N/mm.sup.2, direct impact
strength of at least 100 in-lbs, and reverse impact strength of at
least 160 in-lbs.
17. A glass substrate at least partially coated with the coating
composition of claim 1.
18. 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
polyester resin; (b) a water-dilutable aminoplast resin; and (c) a
water-dilutable polycarbonate-polyurethane resin. The
water-dilutable hydroxy-functional polyester resin has an OH number
of 25 to 350 mg KOH/g solids. The hydroxy-functional polyester
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 polyester 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
polyester resin. As used herein, the term "polyester resin" refers
to oligomeric or polymeric macromolecules comprising ester groups.
Polyester resins include fatty acid-free polyester resins, oil-free
polyester resins, and alkyd polyester resins, which may be produced
by the polycondensation of alcohols and carboxylic acids. The
polyester resins may alternatively also include additional fatty
acids, oils or alkyds in their synthesis.
[0020] In various non-limiting embodiments, the polyol resin
component (a) is a water-dilutable hydroxy-functional polyester
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] The water-dilutable hydroxy-functional polyester resin may
comprise a reaction product of polyhydric alcohols and polybasic
carboxylic acids. As used herein, the term "polyhydric alcohols"
refers to alcohols comprising two or more hydroxyl groups, for
example, diols and triols. As used herein, the term "polybasic
carboxylic acids" refers to carboxylic acids comprising two or more
carboxyl groups, for example, di-carboxylic acids, tri-carboxylic
acids, and tetra-carboxylic acids.
[0022] Suitable polyhydric alcohols include, for example,
1,2-ethylene glycol; diethylene glycol; triethylene glycol;
tetraethylene glycol; 1,2-propylene glycol; dipropylene glycol;
tripropylene glycol; 1,3-propanediol; 1,3-butanediol;
1,4-butanediol; 1,6-hexanediol; neopentyl glycol;
1,4-cyclohexanedimethanol; 1,4-cyclohexanediol; butenediol;
butynediol; hydrogenated bisphenols; trimethylpentanediol;
1,8-octanediol; tricyclodecanedimethanol; trimethylolpropane;
ethoxylated trimethylolpropane; propoxylated trimethylolpropane;
propoxylated glycerol; ethoxylated glycerol; glycerol;
pentaerythritol; dipentaerythritol; sorbitol; castor oil; and
combinations of any thereof.
[0023] Suitable polybasic carboxylic acids include, for example;
phthalic anhydride; isophthalic acid; terephthalic acid; adipic
acid; glutaric acid; sebacic acid; suberic acid; succinic acid;
maleic anhydride; fumaric acid; dimer fatty acids;
tetrahydrophthalic anhydride; hexahydrophthalic anhydride;
cyclohexane dicarboxylic acid; trimellitic anhydride; and
combinations of any thereof. In various non-limiting embodiments, a
water-dilutable hydroxy-functional polyester resin may comprise
condensed residues of polybasic carboxylic acids that are
aliphatic, cycloaliphatic, and/or aromatic.
[0024] In various non-limiting embodiments, a water-dilutable
hydroxy-functional polyester resin may comprise condensed residues
of a monocarboxylic acid such as, for example, benzoic acid;
hexahydrobenzoic acid; butyl benzoic acid; 2-methylbenzoic acid;
2-ethylhexanoic acid; fatty acids and mixtures of fatty acids
(e.g., C.sub.8-C.sub.22 fatty acids) obtained from natural oils
such as, for example, soya fatty acid, safflower oil fatty acid,
cottonseed oil fatty acid, linseed oil fatty acid, ground nut oil
fatty acid, ricinene fatty acid; and combinations of any thereof.
In various non-limiting embodiments, a water-dilutable
hydroxy-functional polyester resin may comprise condensed residues
of a monohydric alcohol such as, for example, butyl glycol, butyl
diglycol, cyclohexanol, polyethylene oxides, polypropylene oxides,
polyethylene/polypropylene oxide copolymers and block copolymers,
and combinations of any thereof.
[0025] Water-dilutable hydroxy-functional polyester resins
comprising a reaction product of polyhydric alcohols and polybasic
carboxylic acids may be formulated as aqueous polyester dispersions
with emulsifier compounds as described, for example, in U.S. Pat.
No. 4,321,170, which is incorporated by reference into this
specification. Water-dilutable hydroxy-functional polyester resins
comprising a reaction product of polyhydric alcohols and polybasic
carboxylic acids may be modified (e.g., urethane-modified) to
covalently incorporate an ionic group, a potentially ionic group,
or a nonionic hydrophilic group, to at least partially impart
water-dilutability (e.g., aqueous solubility or aqueous
dispersability) to the water-dilutable hydroxy-functional polyester
resins by increasing the hydrophilicity of the macromolecules.
Suitable hydroxyl functional carboxylic acids, used in the
polyester synthesis to incorporate an ionic or potentially ionic
group, include mono, di or poly-hydroxycarboxylic acids and
combinations of any thereof. For example, dimethylolpropionic acid
(available from Geo Specialty Chemicals) or dimethylolbutyric acid
can be used.
[0026] In various non-limiting embodiments, a polyester polyol
component may comprise a reaction product of polyhydric alcohols
and polybasic carboxylic acids, optionally, with monohydric
alcohols and/or monocarboxylic acids, as described above. The
polyester 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. The polyester 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 3000, or 1000 to 3000. The polyester polyol may
have an OH number of 25 to 350 mg KOH/g solids.
[0027] Water-dilutable hydroxy-functional polyester resins
comprising reaction products of components may be produced
according to the processes described in U.S. Pat. No. 7,557,156,
which is incorporated by reference into this specification.
[0028] Water-dilutable hydroxy-functional polyester 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 polyester 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
polyester 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 polyester resins
may be colloidal dispersions, molecular solutions, or mixtures of
both.
[0029] In various non-limiting embodiments; the polyol resin
component (a) of the aqueous polyurethane coating compositions may
comprise a water-dilutable hydroxy-functional polyester resin as
described in U.S. Pat. No. 4,028,313; 4,310,499; 4,321,170;
4,331,573; 4,418,174; 5,280,062; 5,331,039; 5,334,637; 5,349,041;
5,569,707; 5,710,209; 5,741,849; 6,620,893; 7,148,307; 7,183,352;
or 7,557,156, which are incorporated by reference into this
specification.
[0030] 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
polyester resin. Suitable water-dilutable hydroxy-functional
polyester resins, are commercially available from Bayer
MaterialScience LLC, Pittsburgh, Pa., USA, under the Bayhydrol.RTM.
trademark.
[0031] 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.
[0032] 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.
[0033] 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.
[0034] 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).
[0035] 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.
[0036] 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.
[0037] 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.
[0038] 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.
[0039] 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-Osocyanatomethylycyclohexane;
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.
[0040] 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.
[0041] 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:
[0042] (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;
[0043] (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;
[0044] (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;
[0045] (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;
[0046] (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
[0047] (6) Polyisocyanates containing oxadiazinetrione groups,
e.g., the reaction product of two moles of a diisocyanate and one
mole of carbon dioxide.
[0048] 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.
[0049] 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.
[0050] In various non-limiting embodiments, a polyisocyanate
component (B1) may comprise at least one of HDI, IPD.sub.1,
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.
[0051] 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.
[0052] 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.
[0053] 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.
[0054] 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.
[0055] 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.
[0056] 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 bisulfate 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).
[0057] 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 dimethyloipropionic 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.
[0058] 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-dilutable
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).
[0059] 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, methylenediamine;
ethylenediamine; propylenediamine; 1,4-butylenediamine;
1,6-hexamethylenediamine; 2-methyl-1,5-pentanediamine (Dyek-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.
[0060] 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).
[0061] 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.
[0062] 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.
[0063] 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.
[0064] 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.
[0065] 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).
[0066] 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.
[0067] 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).
[0068] In various non-limiting embodiments, the one-component
thermally-curable aqueous polyurethane coating compositions
described herein may comprise; 50% to 99% by weight, preferably 50%
to 85% by weight, most preferably 60% to 75% by weight, most
preferably on a solids basis of a water-dilutable
hydroxy-functional polyester resin; and a water-dilutable
aminoplast resin; and 50% to 1% by weight preferably 50% to 15% by
weight, 40% to 25% by weight on a solids basis of a water-dilutable
non-functional polycarbonate-polyurethane resin.
[0069] 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 50:50 to 90:10. 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.
[0070] 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).
[0071] 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, infared heat sources, microwaves, electron beams,
or combination thereof.
[0072] 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.
[0073] 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 100 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 (or greater than) 120
in-lbs, 140 in-lbs, or 160 in-lbs.
[0074] 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.
[0075] 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.
[0076] 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.
[0077] 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.
[0078] 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).
[0079] 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.
[0080] 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, 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.
[0081] 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.
[0082] 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
[0083] One-component thermally-curable aqueous polyurethane coating
compositions comprising a polyol resin, an aminoplast resin, and a
polycarbonate-polyurethane resin were prepared as follows. Aqueous
dispersions of a hydroxy-functional polyester resin (Bayhydrol.RTM.
E XP 2777, Bayer MaterialScience LLC, Pittsburgh, Pa., USA) were
mixed with Cymel.RTM. 327 and Bayhydrol.RTM. XP 2637.
Bayhydrol.RTM. E XP 2777 is a saturated polyester resin provided as
an aqueous dispersion of 64% solids having 2.0% hydroxyl content on
a solids weight basis.
[0084] 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 polyester 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 K L M
Formulations polyester resin dispersion 88.05 66.04 76.12 57.75
46.44 30.80 64.32 48.24 50.00 37.50 39.31 29.48 0.00 aminoplast
resin 9.95 7.46 21.88 15.75 12.36 8.40 33.68 25.26 48.00 36.00
58.69 44.02 14.70 polycarbonate- 0.00 24.50 0.00 24.50 39.20 58.80
0.00 24.50 0.00 24.50 0.00 24.50 83.30 polyurethane resin
dispersion dipropylene glycol 1.6 1.6 1.6 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
0.2 0.2 0.2 mercaptopropyl- trimethoxysilane 3-aminopropyl- 0.2 0.2
0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 triethoxysilane Binder
Resin Component Weight Ratios polyester resin/ 85/15 85/15 70/30
70/30 70/30 70/30 55/45 55/45 40/60 40/60 30/70 30/70 0/100
aminoplast resin (wt/wt on solids) Coating Properties Direct Impact
(in-lbs) 160 160 160 160 160 160 140 160 120 160 100 140 160
Reverse Impact (in-lbs) 160 160 160 160 160 160 160 160 160 160 160
160 160 Microhardness (N/mm.sup.2) 147 75 102 75 30 14 19 23 2 2 1
1 1 Scribe adhesion Pass Pass Pass Pass Pass Pass Pass Pass Pass
Pass Pass Pass Pass
[0085] 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.
[0086] 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 3.0 mils.
[0087] 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."
[0088] 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 impact
strength. Further, addition of non-functional
polycarbonate-polyurethane resin did not have a negative affect on
adhesion. For instance, formulations A, C, G, I, and K did not
contain any polycarbonate-polyurethane resin, but formulations B,
D, H, J, and L contained additions of 25% of a
polycarbonate-polyurethane resin dispersion (10% on a solids
basis), relative to formulations A, C, G, I, and K, respectively.
Comparisons of formulations A and B, formulations C and D,
formulations G and H, formulations I and J, and formulations K and
L, shows that the addition of non-functional
polycarbonate-polyurethane resin generally decreased the hardness
and maintained or increased the impact strength of the cured
coating films.
[0089] Further, formulations C, D, E, and F all had the same weight
ratio of hydroxy-functional polyester resin to aminoplast resin.
Formulation C was free of non-functional polycarbonate-polyurethane
resin, and formulations D though F had increasing non-functional
polycarbonate-polyurethane resin content. A comparison of
formulation C with formulations D though F shows that increasing
the content of non-functional polycarbonate-polyurethane resin
decreases hardness while maintaining high impact strength and
toughness, and good substrate adhesion.
[0090] For the purposes of glass coatings, a combination of high
impact strength and microhardness in the range of about 20
N/mm.sup.2 to 90 N/mm.sup.2 is most desirable. Examples B, D, E,
and H illustrate that a combination of the optimal amount of
polycarbonate-polyurethane resin with the proper polyester to
aminoplast resin ratio surprisingly provides the desired
results.
[0091] 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, and decreased abrasion resistance. 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.
[0092] 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, high abrasion
resistance, 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.
[0093] 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).
* * * * *