U.S. patent application number 17/598941 was filed with the patent office on 2022-06-02 for single component hydrophobic coating.
This patent application is currently assigned to PPG Industries Ohio, Inc.. The applicant listed for this patent is PPG Industries Ohio, Inc.. Invention is credited to Stuart D. Hellring, Cynthia Kutchko, Emily S. Reinhardt, David N. Walters.
Application Number | 20220169890 17/598941 |
Document ID | / |
Family ID | 1000006152953 |
Filed Date | 2022-06-02 |
United States Patent
Application |
20220169890 |
Kind Code |
A1 |
Walters; David N. ; et
al. |
June 2, 2022 |
SINGLE COMPONENT HYDROPHOBIC COATING
Abstract
A coating composition includes a polymer prepared from a mixture
of reactants including (a) a fluorinated polysiloxane and (b) an
alkoxy silane functional resin. The alkoxy silane functional resin
includes a polyurethane resin or an acrylic resin. A substrate at
least partially coated with the coating composition is also
disclosed. A method of condensing a polar fluid by contacting a
substrate at least partially coated with the coating composition
with a polar fluid, such that the polar fluid condenses on at least
a portion of the coated substrate is also disclosed.
Inventors: |
Walters; David N.; (Slippery
Rock, PA) ; Reinhardt; Emily S.; (Allison Park,
PA) ; Kutchko; Cynthia; (Pittsburgh, PA) ;
Hellring; Stuart D.; (Pittsburgh, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PPG Industries Ohio, Inc. |
Cleveland |
OH |
US |
|
|
Assignee: |
PPG Industries Ohio, Inc.
Cleveland
OH
|
Family ID: |
1000006152953 |
Appl. No.: |
17/598941 |
Filed: |
January 28, 2020 |
PCT Filed: |
January 28, 2020 |
PCT NO: |
PCT/US2020/015302 |
371 Date: |
September 28, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
16370217 |
Mar 29, 2019 |
11254838 |
|
|
17598941 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08K 3/36 20130101; C09D
183/04 20130101; C09D 133/08 20130101; C08K 2003/2241 20130101;
C09D 133/10 20130101; C08K 3/22 20130101; C09D 175/04 20130101 |
International
Class: |
C09D 183/04 20060101
C09D183/04; C09D 133/08 20060101 C09D133/08; C09D 133/10 20060101
C09D133/10; C09D 175/04 20060101 C09D175/04 |
Goverment Interests
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
[0001] This invention was made with government support under
Collaboration Agreement No. 201667-140842 with the National Center
for Manufacturing Sciences. The United States government may have
certain rights in this invention.
Claims
1. A coating composition comprising a polymer prepared from a
mixture of reactants comprising (a) a fluorinated polysiloxane; and
(b) an alkoxy silane functional resin, wherein the alkoxy silane
functional resin comprises a polyurethane resin or an acrylic
resin, and wherein the coating composition is a single component
coating composition.
2. The coating composition of claim 1, wherein the mixture of
reactants further comprises (c) a metal alkoxide.
3. The coating composition of claim 1, further comprising a
hydrophobic additive and/or a hydrophilic additive.
4. The coating composition of claim 3, wherein the surface active
coating composition comprises the hydrophobic additive, wherein the
hydrophobic additive comprises a fluorinated treated silica, a
fluorinated silane treated particle, a hydrophobic treated metal
oxide, a rare earth metal oxide, or a combination thereof.
5. The coating composition of claim 1, wherein the fluorinated
polysiloxane comprises polytrifluoropropylmethylsiloxane.
6. The coating composition of claim 1, further comprising a
coupling agent.
7. The coating composition of claim 6, wherein the coupling agent
comprises a silane, an alkoxy silane, a fluoroalkylsilane, an
aminopropyltriethoxysilane, or some combination thereof.
8. The coating composition of claim 3, wherein the hydrophilic
additive and/or the hydrophobic additive comprises at least 1
weight percent of the coating composition based on total solids
weight of the coating composition.
9. The coating composition of claim 2, wherein the metal alkoxide
comprises at least 0.5 weight percent of the coating composition
based on total solids weight of the coating composition.
10. The coating composition of claim 1, wherein, when applied to a
substrate and cured to form a coating, the coating is
hydrophobic.
11. The coating composition of claim 1, wherein, when applied to a
substrate and cured to form a coating, the coated substrate
exhibits a water contact angle of at least 140.degree..
12. The coating composition of claim 3 wherein, when applied to a
substrate and cured to form a coating, the coating comprises a
hydrophobic portion comprising at least a fluorinated portion of
the polymer and a hydrophilic portion comprising the hydrophilic
additive.
13. The coating composition of claim 3, wherein the coating
composition comprises the hydrophilic additive, wherein the
hydrophilic additive comprises nano-sized particles comprising
titanium dioxide, aminopropylsilane treated silica particles,
untreated silica particles, or some combination thereof.
14. The coating composition of claim 1, wherein the alkoxy silane
functional resin comprises at least 4 alkoxy groups bonded to
silicon atoms.
15. The coating composition of claim 1, wherein when cured, a
coating formed from the coating composition exhibits a hardness
value greater than a hardness value of the same coating prepared
from a coating composition not including the alkoxy silane
functional resin.
16. The coating composition of claim 1, further comprising a
thermally conductive material comprising a metallic flake, a
metallic powder, conductive carbon, or some combination
thereof.
17. A substrate at least partially coated with the coating
composition of claim 1.
18. The substrate of claim 17, wherein when the coating composition
is solidified to form a coating layer, the coating layer has a film
thickness of up to 3 mils.
19. The substrate of claim 17, wherein the substrate comprises a
surface of a component in a HVAC system.
20. A method of condensing a polar fluid comprising: contacting a
substrate at least partially coated with a coating formed from a
coating composition comprising a polymer prepared from a mixture of
reactants comprising (a) a fluorinated polysiloxane; and (b) an
alkoxy silane functional resin, wherein the alkoxy silane
functional resin comprises a polyurethane resin or an acrylic
resin, and wherein the coating composition is a single component
coating composition, with a polar fluid, such that the polar fluid
condenses on at least a portion of the coated substrate.
Description
FIELD OF THE INVENTION
[0002] The present invention relates to a coating composition,
substrates coated with the coating composition, and methods of
condensing a polar fluid by contacting a substrate at least
partially coated with the coating composition with said polar
fluid.
BACKGROUND OF THE INVENTION
[0003] Coating compositions applied on substrates and cured to form
a coating are used in various industries to facilitate the
condensation of water, or other polar fluids, on the coating from
the surrounding air. Examples include coating compositions used on
air wells or on heating, ventilation, and air conditioning (HVAC)
systems (e.g., condenser tubes thereof). Efficiency of heat
exchangers can be improved by the rapid condensation of the water
from the air in the area of these coatings, followed by rapid
removal of the water droplet from the coated surface via gravity
and/or forced air flows over the heat exchanger surface.
Accordingly, coating surfaces which provide high water contact
angles and low values for hysteresis are desirable to promote more
efficient and cost effective operation of heat exchangers.
SUMMARY OF THE INVENTION
[0004] The present invention is directed to a coating composition
comprising a polymer prepared from a mixture of reactants including
(a) a fluorinated polysiloxane and (b) an alkoxy silane functional
resin. The alkoxy silane functional resin includes a polyurethane
resin or an acrylic resin.
[0005] The present invention is also directed to a method of
condensing a polar fluid including: contacting a substrate at least
partially coated with a coating composition with a polar fluid,
such that the polar fluid condenses on at least a portion of the
coated substrate. The coating composition includes a polymer
prepared from a mixture of reactants including (a) a fluorinated
polysiloxane and (b) an alkoxy silane functional resin. The alkoxy
silane functional resin includes a polyurethane resin or an acrylic
resin.
DESCRIPTION OF THE INVENTION
[0006] For purposes of the following detailed description, it is to
be understood that the invention may assume various alternative
variations and step sequences, except where expressly specified to
the contrary. Moreover, other than in any operating examples, or
where otherwise indicated, all numbers expressing, for example,
quantities of ingredients used in the specification and claims are
to be understood as being modified in all instances by the term
"about". Accordingly, unless indicated to the contrary, the
numerical parameters set forth in the following specification and
attached claims are approximations that may vary depending upon the
desired properties to be obtained by the present invention. 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 should at least be construed in light of the number of
reported significant digits and by applying ordinary rounding
techniques.
[0007] Notwithstanding that the numerical ranges and parameters
setting forth the broad scope of the invention are approximations,
the numerical values set forth in the specific examples are
reported as precisely as possible. Any numerical value, however,
inherently contains certain errors necessarily resulting from the
standard variation found in their respective testing
measurements.
[0008] Also, it should be understood that any numerical range
recited herein is intended to include all sub-ranges subsumed
therein. 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 of equal to or
less than 10.
[0009] In this application, the use of the singular includes the
plural and plural encompasses singular, unless specifically stated
otherwise. In addition, in this application, the use of "or" means
"and/or" unless specifically stated otherwise, even though "and/or"
may be explicitly used in certain instances. Further, in this
application, the use of "a" or "an" means "at least one" unless
specifically stated otherwise. For example, "an" alkoxy silane
functional resin, "a" fluorinated polysiloxane, and the like refer
to one or more of these items. Also, as used herein, the term
"polymer" is meant to refer to prepolymers, oligomers, and both
homopolymers and copolymers. The term "resin" is used
interchangeably with "polymer."
[0010] As used herein, the transitional term "comprising" (and
other comparable terms, e.g., "containing" and "including") is
"open-ended" and is open to the inclusion of unspecified matter.
Although described in terms of "comprising", the terms "consisting
essentially of" and "consisting of" are also within the scope of
the invention.
[0011] The present invention may be directed to a coating
composition comprising a polymer prepared from a mixture of
reactants including (a) a fluorinated polysiloxane and (b) an
alkoxy silane functional resin, wherein the alkoxy silane
functional resin may include a polyurethane resin or an acrylic
resin. A coating composition may refer to a coating composition
that condenses water (or other polar fluid) from the surroundings
and onto a substrate when the coating composition is applied to a
substrate and cured. A coating composition, when applied to the
substrate and cured, may contribute to the coated substrate
exhibiting other advantageous properties, such as easy-to-clean,
self-cleaning, anti-fouling, and/or anti-fogging (e.g., promoting
condensation of water in the form of a film rather than in the form
of small droplets) properties.
[0012] The polymer may be prepared from a mixture comprising a
fluorinated polysiloxane. As used herein, the term "polysiloxane"
refers to a polymer with a backbone or main chain that contains one
or more Si--O--Si linkages. The polysiloxane may include a single
polysiloxane or a mixture of polysiloxanes. The polysiloxane may
have the general structure of Formula I below:
##STR00001##
[0013] In Formula I, n may range from at least 1 to a maximum of
1,000, or 1 to 100, and each R.sub.a and R.sub.b independently
represents a group selected from hydrogen, a hydroxyl group, a
substituted or unsubstituted hydrocarbon group, and mixtures
thereof. Each individual R.sub.a group may be the same or different
than other R.sub.a groups and each individual R.sub.b group may be
the same or different than other R.sub.b groups. A fluorinated
polysiloxane may have the general structure of Formula I wherein at
least one R.sub.b group contains a fluorinated group. R.sub.b may
be an alkyl chain of one or more carbons wherein one or more
fluorine groups is attached to one or more of the carbons in the
alkyl chain. The fluorine groups may be attached to the terminal
carbon or the other carbons along the alkyl chain. Suitable
fluorinated polysiloxanes include, but are not limited to,
polytrifluoropropylmethylsiloxane such as the polymer shown in
Formula II. The fluorinated polysiloxane may be silanol
terminated.
##STR00002##
[0014] The polymer component (a) may include at least two
polysiloxanes, a first fluorinated polysiloxane and a second
polysiloxane, which are different from one another. The fluorinated
polysiloxane may be present in the coating composition in an amount
of 5 weight percent or greater, such as 10 weight percent or
greater, 20 weight percent or greater, 30 weight percent or
greater, 40 weight percent or greater, or 50 weight percent or
greater, based on total solids weight of the coating composition.
The fluorinated polysiloxane may be present in the coating
composition in an amount of 80 weight percent or less, such as 75
weight percent or less, based on total solids weight of the coating
composition. The fluorinated polysiloxane may be present in the
coating composition in an amount of 5-80 weight percent, 10-75
weight percent, 20-75 weight percent, 30-75 weight percent, 40-75
weight percent, 50-80 weight percent, or 50-75 weight percent,
based on total solids weight of the coating composition. The
fluorinated polysiloxane may impart hydrophobicity (by virtue of a
hydrophobic portion present in the polymer) to a cured coating
prepared including the fluorinated polysiloxane in the coating
composition. The hydrophobic portion is defined as portion of the
coating composition that exhibits a water contact angle (WCA) of at
least 90.degree. using Kruss Drop Shape Analysis. As reported
herein, Kruss Drop Shape Analysis was performed on a Kruss Drop
Shape Analyzer (DSA 100) according to ASTM test method D7334.
[0015] The polymer may be prepared from a mixture comprising an
alkoxy silane functional resin. An alkoxy silane functional resin
includes at least one pendant and/or terminal alkoxy silane group.
A "pendant group", also referred to as a "side chain", is an
offshoot from the polymer main chain and is not part of the main
chain, and a "terminal group" refers to a functional group
positioned at the end of the polymer main chain. The term "silane"
refers to a compound derived from SiH.sub.4 by substituting organic
groups for one or more of the hydrogen atoms, and the term "alkoxy"
refers to an --O-alkyl group. Further, an "alkoxy silane" refers to
a silane compound with at least one alkoxy group bonded to a
silicon atom. The alkoxy silane can also comprise multiple alkoxy
groups bonded to the silicon atom. The alkoxy silane can comprise
two alkoxy groups, or three alkoxy groups, bonded to the silicon
atom. As such, the alkoxy silane can have one, two, or three alkoxy
groups. The alkoxy groups that can be bonded to the silicon atom
include, but are not limited to, alkoxy groups with a C.sub.1 to
C.sub.20 carbon chain, a C.sub.1 to C.sub.10 carbon chain, a
C.sub.1 to C.sub.6 carbon chain, or a C.sub.1 to C.sub.4 carbon
chain. Suitable alkoxy groups include methoxy, ethoxy, propoxy,
isopropoxy, butoxy, sec-butoxy, isobutoxy, t-butoxy, pentoxy,
isopentoxy, and combinations thereof.
[0016] An alkoxy silane functional resin can comprise a particular
polymer architecture, such as a linear polymer comprising pendant
and/or terminal alkoxy silane groups. The alkoxy silane functional
resin may be a branched polymer comprising pendant and/or terminal
alkoxy silane groups. The alkoxy silane functional resin may
contain a total of at least 2 alkoxy groups bonded to silicon
atoms, such as at least 3, at least 4, at least 6, or at least 9
alkoxy groups bonded to silicon atoms.
[0017] The alkoxy silane functional resin may include a
polyurethane resin. As used herein, the term "polyurethane resin"
refers to a polymer comprising at least one urethane linkage. The
polyurethane resin can be formed according to any method known in
the art, such as by reacting at least one polyisocyanate with one
or more compound(s) having functional groups that are reactive with
the isocyanate functionality of the polyisocyanate. Reactive
functional groups can be active hydrogen-containing functional
groups such as hydroxyl groups, thiol groups, amine groups, and
acid groups like carboxylic acid groups. A hydroxyl group may react
with an isocyanate group to form a urethane linkage. A primary or
secondary amine group may react with an isocyanate group to form a
urea linkage. Generally the reaction mixture includes at least one
hydroxyl-functional reactive compound such as a polyol for
formation of urethane functionality. Typically the compound(s)
having functional groups that are reactive with the isocyanate
functionality of the polyisocyanate comprise at least one compound
having two or more active hydrogen-containing functional groups,
e.g. selected from those mentioned above, per molecule.
[0018] Suitable reactive compounds include polyols,
polyisocyanates, compounds containing carboxylic acid groups
including diols containing carboxylic acid groups, polyamines,
polythiols, and/or other compounds having reactive functional
groups, such as hydroxyl groups, thiol groups, amine groups, and
carboxylic acids. The reactive compounds may comprise an
alkoxysilane group to impart alkoxy silane functionality to the
polyurethane resin.
[0019] An isocyanate-functional polyurethane prepolymer may be
formed by reacting a stoichiometric excess of polyisocyanate with
one or more reactive compounds as described above, such as a
polyol. The isocyanate-functional polyurethane prepolymer may be
reacted with an additional reactive compound which comprises an
alkoxy silane to yield an alkoxy silane functional polyurethane.
The additional reactive compound may be an alkoxy silane functional
primary or secondary amine, which reacts with the polyurethane
prepolymer to form a urea linkage. The alkoxy silane functional
reactive compound may comprise terminal alkoxy silane groups to
yield a polyurethane with terminal alkoxy silane groups.
[0020] The alkoxy silane functional resin may include an acrylic
resin. As used herein, the term "acrylic resin" refers to a polymer
formed from at least one acrylic monomer. The acrylic resin may be
formed according to any method known in the art by using any number
of acrylic monomers, including alkyl (meth)acrylates such as ethyl
(meth)acrylate, methyl (methacrylate), and butyl (meth)acrylate,
functional acrylates such as hydroxyethyl (meth)acrylate, cyclic
and polycyclic (meth)acrylics such as benzyl (meth)acrylate,
cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate, and
acrylamides such as N-butoxy methyl acrylamide. The acrylic monomer
may be an alkoxy silane functional acrylic monomer. An acid
functional (meth)acrylic acid and an alkyl (meth)acrylate may each
be used. Mixtures of (meth)acrylic resins can also be used. It will
be understood that (meth)acrylic and like terms refers to both
methacrylic and acrylic.
[0021] An alkoxy silane functional acrylic resin may be a polymer
formed from at least one alkoxy silane functional acrylic monomer.
An alkoxy silane functional acrylic resin may be a polymer formed
from at least one isocyanate functional acrylic monomer and/or
epoxy functional acrylic monomer, which is further reacted to form
the alkoxy silane functional acrylic resin. An isocyanate
functional acrylic residue may be reacted with an alkoxy silane
functional compound having a functional group that is reactive with
the isocyanate functionality, such as an alkoxy silane functional
amine. An epoxy functional acrylic residue may be reacted with an
alkoxy silane functional compound having a functional group that is
reactive with the epoxy functionality, such as an alkoxy silane
functional amine or an alkoxy silane functional thiol. An alkoxy
silane functional acrylic resin may be a polymer formed from a
hydroxyl functional acrylic resin that is reacted with an alkoxy
silane functional compound having a functional group that is
reactive with the hydroxyl functionality, such as an alkoxy silane
functional isocyanate.
[0022] The polymer may also include (c) a metal alkoxide. By
"alkoxide" it is meant the conjugate base of an alcohol (Y--OH)
where Y may be a C.sub.1-C.sub.10 linear or branched alkyl group.
The metal alkoxide may include a polyvalent metal. Suitable metal
alkoxides include zirconium alkoxide (such as zirconium butoxide or
zirconium methoxide), titanium alkoxide, tantalum alkoxide, hafnium
alkoxide, aluminum alkoxide, zirconium isoproproxide isopropanol,
or mixtures thereof. The metal alkoxide may be present in the
coating composition in an amount of at least 0.5 weight percent, at
least 1 weight percent, or at least 2 weight percent, based on
total solids weight of the coating composition. The metal alkoxide
may be present in the coating composition in an amount of less than
20 weight percent, such as less than 15 weight percent, less than
10 weight percent, or less than 5 weight percent, based on total
solids weight of the coating composition. The metal alkoxide may be
present in the coating composition in an amount of 0.5-20 weight
percent, such as, 0.5-5 weight percent, 0.5-10 weight percent,
0.5-15 weight percent, 1-20 weight percent, 1-10 weight percent,
1-5 weight percent, 2-20 weight percent, 2-10 weight percent, or
2-5 weight percent, based on total solids weight of the coating
composition.
[0023] The polymer may also include a hydrophobic and/or a
hydrophilic additive. A "hydrophobic additive", as used herein, is
an additive that increases the water contact angle of the cured
coating composition. A "hydrophilic additive", as used herein, is
an additive that decreases the water contact angle of the cured
coating composition. The additive may be a hydrophilic additive,
which may not be a reactant that forms the polymer. The hydrophilic
additive may be added after the polymer, as previously described,
is prepared. The hydrophilic additive may impart hydrophilicity
(create a hydrophilic portion) to a cured coating prepared
including the hydrophilic additive in the coating composition. The
hydrophilic portion is defined as a portion of the coating
composition that exhibits a WCA of less than 90.degree. using the
Kruss Drop Shape Analysis. Suitable hydrophilic additives include
nano-sized particles of titanium dioxide (TiO.sub.2),
aminopropylsilane treated silica, untreated silica, and/or mixtures
thereof. By "nano-sized" it is meant that the particles of
TiO.sub.2 have a mean particle size of no more than 100 nanometers,
according to ASTM F1877-16.
[0024] The hydrophilic additive may be present in the coating
composition in an amount of at least 1 weight percent, at least 10
weight percent, at least 15 weight percent, at least 20 weight
percent, or at least 25 weight percent, based on total solids
weight of the coating composition. The hydrophilic additive may be
present in the coating composition in an amount less than 50 weight
percent, less than 40 weight percent, or less than 35 weight
percent based on total solids weight of the coating composition.
The hydrophilic additive may be present in the coating composition
in an amount of 10-50 weight percent, 15-40 weight percent, 20-35
weight percent, or 25-35 weight percent, based on total solids
weight of the coating composition. An effective amount of the
hydrophilic additive may be added to the coating composition such
that, when applied to the substrate and cured, the overall coating
is hydrophobic. A hydrophilic coating is defined as the overall
cured coating demonstrating a WCA of less than 90.degree. using
Kruss Drop Shape Analysis. A hydrophobic coating is defined as the
overall cured coating demonstrating a WCA of at least 90.degree.
using Kruss Drop Shape Analysis. A superhydrophobic coating is
defined as the overall cured coating demonstrating a WCA of at
least 150.degree. using Kruss Drop Shape Analysis. As used herein,
the term "overall coating" refers to the coating when considered as
a whole, as opposed to the characteristics of any one portion of
the coating. An effective amount of the hydrophilic additive may be
added to the coating composition such that, when applied to the
substrate and cured, the overall cured coating exhibits a WCA of at
least 100.degree., at least 110.degree., at least 120.degree., at
least 130.degree., at least 140.degree., or at least 150.degree..
An effective amount of the hydrophilic additive may be added to the
coating composition such that, when applied to the substrate and
cured, the overall coating is superhydrophobic. An effective amount
of the hydrophilic additive may be added to the coating composition
such that, when applied to the substrate and cured, the overall
cured coating exhibits a WCA of at least 150.degree. and a
hysteresis of no more than 25.degree. or no more than 10.degree..
As used herein, hysteresis is defined as a difference of the
advancing contact angle and the receding contact angle of a drop of
liquid (such as water) on a plane angled between 0.degree. and
90.degree. relative to the horizontal. Hysteresis may be measured
using Kruss Drop Shape Analysis.
[0025] The additive may be a hydrophobic additive, which may not be
a reactant that forms the polymer. The hydrophobic additive may be
added after the polymer, as previously-described, is prepared. The
hydrophobic additive may impart hydrophobicity (create a
hydrophobic portion) to a cured coating prepared including the
hydrophobic additive in the coating composition. The hydrophobic
portion is defined as a portion of the coating composition that
exhibits a WCA of at least 90.degree. using Kruss Drop Shape
Analysis. Suitable hydrophobic additives include fluorinated
treated particles, such as a fluorinated treated silica,
fluorinated silane treated particles, such as a fluorinated silane
treated silica, a hydrophobic treated metal oxide, a rare earth
metal oxide, or mixtures thereof.
[0026] The hydrophobic additive may be present in the coating
composition in an amount of at least 1 weight percent, at least 3
weight percent, at least 5 weight percent, at least 10 weight
percent, or at least 15 weight percent based on total solids weight
of the coating composition. The hydrophobic additive may be present
in the coating composition in an amount less than 30 weight
percent, less than 25 weight percent, less than 20 weight percent,
or less than 18 weight percent based on total solids weight of the
coating composition. The hydrophobic additive may be present in the
coating composition in an amount of 3-30 weight percent, 5-25
weight percent, 10-20 weight percent, or 15-20 weight percent,
based on total solids weight of the coating composition. An
effective amount of the hydrophobic additive may be added to the
coating composition such that, when applied to the substrate and
cured, the overall coating is hydrophobic. An effective amount of
the hydrophobic additive may be added to the coating composition
such that, when applied to the substrate and cured, the overall
cured coating exhibits a WCA of at least 100.degree., at least
110.degree., at least 120.degree., at least 130.degree., at least
140.degree., or at least 150.degree.. An effective amount of the
hydrophobic additive may be added to the coating composition such
that, when applied to the substrate and cured, the overall cured
coating is superhydrophobic. An effective amount of the hydrophobic
additive may be added to the coating composition such that, when
applied to the substrate and cured, the overall cured coating
exhibits a WCA of at least 150.degree. and a hysteresis of no more
than 25.degree. or no more than 10.degree..
[0027] The coating composition may further include a coupling
agent. The coupling agent may include functional groups such as
hydroxyl groups, methoxide groups, or ethoxide groups that are
reactive with a substrate such as aluminum to provide or enhance
adhesion between the coating composition and the substrate. The
coupling agent may include a silane, an alkoxy silane, a
fluoroalkylsilane, an aminopropyltriethoxysilane, and/or mixtures
thereof. The coupling agent may be an alkoxy silane, such as
3-aminopropyltriethoxysilane. Other coupling agents may be included
in the coating composition based on the composition of the
substrate and/or the other components included in the coating
composition.
[0028] The alkoxy silane functional resin may react with itself or
a coupling agent to form a crosslinked polymer network. The use of
a coupling agent serves to increase the crosslink density of the
crosslinked polymer network. The use of a coupling agents, such as
an aminopropyltriethoxysilane, may also serve to accelerate the
cure response of the coating composition. The crosslinked polymer
network may have a crosslink density of 1.5 to 3.5 mmole/cm.sup.3
as measured by ASTM F2214-02.
[0029] The coating composition may further include a thermally
conductive material. The thermally conductive material may include
a metallic material or a conductive carbonaceous material. The
thermally conductive material may include a metallic flake, a
metallic powder, conductive carbon, or some combination thereof.
The thermally conductive material may include copper, graphene,
zinc cerium, or some combination thereof.
[0030] Any of the coating compositions described herein may include
additional materials. Suitable additional materials that can be
used with the coating compositions of the present invention
include: colorants (e.g., pigments and/or dyes), plasticizers,
abrasion resistant particles, corrosion resistant particles,
corrosion inhibiting additives, fillers including, but not limited
to, clays, inorganic minerals, anti-oxidants, hindered amine light
stabilizers, UV light absorbers and stabilizers, surfactants, flow
and surface control agents, thixotropic agents, organic
co-solvents, reactive diluents, catalysts, reaction inhibitors, and
other customary auxiliaries.
[0031] After preparing the coating composition, the coating
composition may be applied to a substrate and cured to form a
coating. The substrate may be any suitable material. The substrate
may be metallic or non-metallic. Metallic substrates may include,
but are not limited to, tin, steel (including stainless steel,
electrogalvanized steel, cold rolled steel, and hot-dipped
galvanized steel, among others), aluminum, aluminum alloys,
zinc-aluminum alloys, steel coated with a zinc-aluminum alloy, or
aluminum plated steel. The metallic substrates may also further
include a metal pretreatment coating or conversion coating.
Suitable pretreatment coatings or conversion coatings include, but
are not limited to, zinc phosphate, iron phosphate, or
chromate-containing pretreatments. Other suitable pretreatment
coatings or conversion coatings include, but are not limited to,
thin-film pretreatment coatings such as a zirconium or
titanium-containing pretreatment. The metal pretreatment coating
may also include a sealer, such as a chromate or non-chromate
sealer.
[0032] Non-metallic substrates may comprise polymeric materials.
Suitable polymeric materials for the substrate may include plastic,
polyester, polyolefin, polyamide, cellulosic, polystyrene,
polyacrylic, poly(ethylene naphthalate), polypropylene,
polyethylene, nylon, EVOH, polylactic acid, other "green" polymeric
substrates, poly(ethyleneterephthalate) (PET), polycarbonate,
polycarbonate acrylonitrile butadiene styrene (PC/ABS), or
polyamide. Other non-metallic substrates may include glass, wood,
wood veneer, wood composite, particle board, medium density
fiberboard, cement, stone, paper, cardboard, textiles, leather,
both synthetic and natural, and the like. Non-metallic substrates
may also include a treatment coating that is applied before
application of the coating, which increases the adhesion of the
coating to the substrate.
[0033] The substrate may be a portion of a HVAC system, or other
system including a heat exchanger, comprising metal, such as
aluminum, an aluminum alloy, or stainless steel. The substrate may
be a surface of condenser tubes of the HVAC system, such that the
condenser tubes are coated with the coating composition, and the
coated condenser tubes may condense water onto the surface thereof.
Alternatively, the substrate may be glass, such that the glass
coated by the coating composition renders the glass self-cleaning
or easy-to-clean.
[0034] The coating composition may be applied over a component of
an HVAC system or other system including a heat exchanger, and the
coating composition may be formulated and/or applied so as to avoid
excessively insulating the component. The degree to which the
coating formed from the applied coating composition insulates the
component can be expressed by the resistance to heat flow (R-value)
of the coating. An R-value for the coated substrate and/or uncoated
substrate and/or of the coating itself may be determined. R-value
can be determined using the following formula:
R=l/.lamda.
where R is the resistance to heat flow, l is the thickness of the
material in meters, and .lamda. is the thermal conductivity of the
material in W/mK, such that R has a unit of meters squared Kelvin
per Watt (m.sup.2K/W).
[0035] To minimize the R-value of the coating, the
previously-described thermally conductive material may be included
to increase the thermal conductivity of the material, thereby
reducing the R-value of the coating and/or the coated
substrate.
[0036] To minimize the R-value of the coating, the thickness of the
coating may be minimized, thereby reducing the R-value of the
coating and/or the coated substrate. The thickness of the coating
may be up to 3 mils, such as up to 2 mils, or up to 1 mil. The
thickness of the coating may range from 0.5-3 mils, such as 0.5-2.5
mils, 0.5-2 mils, 0.5-1.5 mils, 0.5-1 mils, 1-3 mils, 1-2.5 mils,
1-2 mils, or 1-1.5 mils.
[0037] Application of the coating composition to the substrate
renders the substrate surface active. Applying the coating
composition to the substrate, such as a metal substrate, provides a
coated surface of the substrate that is capable of condensing polar
fluid (e.g., water) from the surrounding air onto the surface of
the coated substrate. Applying the coating composition to the
substrate, such as glass, may provide a coated glass surface that
is easy-to-clean or self-cleaning.
[0038] The coating compositions described herein may be applied by
any means known in the art, such as electrocoating, spraying,
electrostatic spraying, dipping, rolling, brushing, and the like.
The coating composition may be applied to a substrate by spraying,
such as by using a syphon-feed spray gun. The coating composition
may be spray applied to the substrate at a number of different
thicknesses (e.g., using different numbers of passes).
[0039] The coating composition, when applied to the substrate and
cured to form a coating, may have a hardness value of about 30
N/mm.sup.2 at 24 hours and a maximum hardness value of 150
N/mm.sup.2 when fully cured, as measured by using a FISCHERSCOPE
HM2000, a professional microhardness measurement instrument for the
analysis of mechanical and elastic properties of materials by means
of nanoindentation. The coating composition may exhibit a hardness
value greater than a hardness value of the same coating prepared
from a coating composition not including the alkoxy silane
functional resin.
[0040] The coating composition, when applied to the substrate and
cured to form a coating, may render the coated substrate
hydrophobic. The coating composition, when applied to the substrate
and cured to form a coating, may render the coated substrate
hydrophobic, so as to exhibit a WCA of at least 140.degree.. The
coating composition, when applied to the substrate and cured to
form a coating, may render the coated substrate superhydrophobic.
The coating composition, when applied to the substrate and cured to
form a coating, may render the coated substrate superhydrophobic,
such that it exhibits a WCA of at least 150.degree. and a
hysteresis of no more than 25.degree..
[0041] When the coating composition is applied to the substrate and
cured to form a coating, the cured coating may include at least one
hydrophobic portion including at least a fluorinated portion of the
polymer and at least one hydrophilic portion including the
hydrophilic additive. The hydrophobic portion may exhibit a WCA of
at least 90.degree., while the hydrophilic portion may exhibit a
WCA of less than 90.degree.. It will be appreciated that, while the
cured coating may include at least one hydrophobic portion and at
least one hydrophilic portion, the overall coating may be
hydrophobic, such that the overall cured coating exhibits a WCA
that is hydrophobic, as measured by Kruss Drop Shape Analysis.
[0042] The coating composition, when applied to a substrate and
cured to form a coating, may include a plurality of hydrophobic
portions and a plurality of hydrophilic portions. The coating
composition may include alternating hydrophobic and hydrophilic
portions. Alternating hydrophobic and hydrophilic portions may mean
that at least one of the hydrophobic portions is positioned between
at least two of the hydrophilic portions not in direct contact with
one another and/or at least one of the hydrophilic portions is
positioned between at least two of the hydrophobic portions not in
direct contact with one another. It will be appreciated that, while
the cured coating may include alternating hydrophobic and
hydrophilic portions, the overall coating may be hydrophobic, such
that the overall cured coating exhibits a WCA that is
hydrophobic.
[0043] The present invention further includes the subject matter of
the following clauses.
[0044] Clause 1: A coating composition comprising a polymer
prepared from a mixture of reactants comprising (a) a fluorinated
polysiloxane; and (b) an alkoxy silane functional resin, wherein
the alkoxy silane functional resin comprises a polyurethane resin
or an acrylic resin.
[0045] Clause 2: The coating composition of clause 1, wherein the
mixture of reactants further comprises (c) a metal alkoxide.
[0046] Clause 3: The coating composition of clause 1 or 2, further
comprising a hydrophobic additive and/or a hydrophilic
additive.
[0047] Clause 4: The coating composition of clause 3, wherein the
surface active coating composition comprises the hydrophobic
additive, wherein the hydrophobic additive comprises a fluorinated
treated silica, a fluorinated silane treated silica, a fluorinated
silane treated particle, a hydrophobic treated metal oxide, a rare
earth metal oxide, or some combination thereof.
[0048] Clause 5: The coating composition of any of the preceding
clauses, wherein the fluorinated polysiloxane comprises
polytrifluoropropylmethylsiloxane.
[0049] Clause 6: The coating composition of any of the preceding
clauses, further comprising a coupling agent.
[0050] Clause 7: The composition of clause 6, wherein the coupling
agent comprises a silane, an alkoxy silane, a fluoroalkylsilane, an
aminopropyltriethoxysilane, or some combination thereof.
[0051] Clause 8: The coating composition of any of clauses 3-7,
wherein the hydrophilic additive and/or the hydrophobic additive
comprises at least 1 weight percent of the surface active coating
composition based on total solids weight of the surface active
coating composition.
[0052] Clause 9: The coating composition of any of clauses 2-8,
wherein the metal alkoxide comprises at least 0.5 weight percent of
the surface active coating composition based on total solids weight
of the surface active coating composition.
[0053] Clause 10: The coating composition of any of the preceding
clauses, wherein, when applied to a substrate and cured to form a
coating, the coating is hydrophobic.
[0054] Clause 11: The coating composition of any of the preceding
clauses, wherein, when applied to a substrate and cured to form a
coating, the coated substrate exhibits a water contact angle of at
least 140.degree..
[0055] Clause 12: The coating composition of any of clauses 3-11,
wherein, when applied to a substrate and cured to form a coating,
the coating comprises a hydrophobic portion comprising at least a
fluorinated portion of the polymer and a hydrophilic portion
comprising the hydrophilic additive.
[0056] Clause 13: The coating composition of any of clauses 3-12,
wherein the surface active coating composition comprises the
hydrophilic additive, wherein the hydrophilic additive comprises
nano-sized particles comprising titanium dioxide, aminopropylsilane
treated silica particles, untreated silica particles, or some
combination thereof.
[0057] Clause 14: The coating composition of any of the preceding
clauses, wherein the alkoxy silane functional resin comprises at
least 4 alkoxy groups bonded to silicon atoms.
[0058] Clause 15: The coating composition of clause 14, wherein the
alkoxy silane functional resin comprises at least 6 alkoxy groups
bonded to silicon atoms.
[0059] Clause 16: The coating composition of clause 14 or 15
wherein the alkoxy silane functional resin comprises at least 9
alkoxy groups bonded to silicon atoms.
[0060] Clause 17: The coating composition of any of the preceding
clauses, wherein when cured, a coating formed from the surface
active coating composition exhibits a hardness value greater than a
hardness value of the same coating prepared from a coating
composition not including the alkoxy silane functional resin.
[0061] Clause 18: The coating composition of any of the preceding
clauses, wherein the hardness value is less than or equal to 150
N/mm.sup.2 when fully cured.
[0062] Clause 19: The coating composition of any of the preceding
clauses, wherein the crosslink density is between 1.5 and 3.5
mmole/cm.sup.3 when cured.
[0063] Clause 20: The coating composition of any of the preceding
clauses, wherein, when applied to a substrate and cured to form a
coating, the coated substrate exhibits a water contact angle of at
least 150.degree. and a hysteresis of no more than 25.degree..
[0064] Clause 21: The coating composition of any of the preceding
clauses, wherein, when applied to a substrate and cured to form a
coating, the coating is superhydrophobic.
[0065] Clause 22: The coating composition of any of the preceding
clauses, further comprising a cross-linking agent.
[0066] Clause 23: The coating composition of any of clauses 2-22,
wherein the metal alkoxide comprises 0.5-10 weight percent of the
coating composition based on total solids weight of the coating
composition.
[0067] Clause 24: The coating composition of clause 23, wherein the
metal alkoxide comprises 0.5-5 weight percent of the coating
composition based on total solids weight of the coating
composition.
[0068] Clause 25: The coating composition of any of clauses 1-24,
further comprising a thermally conductive material comprising a
metallic flake, a metallic powder, conductive carbon, or some
combination thereof.
[0069] Clause 26: A substrate at least partially coated with the
coating composition of any of the preceding clauses.
[0070] Clause 27: The substrate of clause 26, wherein the substrate
comprises metal or glass.
[0071] Clause 28: The substrate of clause 26 or 27, wherein the
substrate comprises a surface of a component in a HVAC system.
[0072] Clause 29: The substrate of any of clauses 26-28, wherein
when the coating composition is solidified to form a coating layer,
the coating layer has a film thickness of up to 3 mils.
[0073] Clause 30: A method of condensing a polar fluid comprising:
contacting the substrate of any of clauses 26-29 with a polar
fluid, such that the polar fluid condenses on at least a portion of
the coated substrate.
[0074] Clause 31: The method of clause 30, wherein the polar fluid
comprises water.
[0075] The following examples are presented to exhibit the general
principles of the invention. The invention should not be considered
as limited to the specific examples presented. All parts and
percentages in the examples are by weight unless otherwise
indicated.
Example 1
Water Contact Angle for Room Temperature Cured Coating
Composition
[0076] A coating composition was prepared from the components
listed in Table 1.
TABLE-US-00001 TABLE 1 Solution Weight % Component Weight Solids on
solids FMS-9922 Polytrifluoropropylmethylsiloxane 8.4 8.4 21.7%
silanol terminated.sup.1 Nano TiO.sub.2-P25, Aeroxide.sup.2 12.6
12.6 32.6% 3-Aminopropyltriethoxysilane.sup.3 2.0 2.0 5.2% n-Butyl
acetate.sup.4 47.8 0 0.0% Zirconium butoxide.sup.5 1.4 1.4 3.6%
Dibutyltin diacetate.sup.6 0.25 0.25 0.6% Alkoxy silane
urethane.sup.7 24.15 14 36.2% 96.60 38.65 100.0% .sup.1Available
from Gelest, Inc. (Morrisville, Pennsylvania) .sup.2Particle size
of 25 mn. Available from Evonik Industries (Essen, Germany)
.sup.3Available from Gelest, Inc. (Morrisville, Pennsylvania)
.sup.4Available from Fisher Scientific (Hampton, New Hampshire)
.sup.5Available from Sigma Aldrich (St. Louis, Missouri)
.sup.6Available from Sigma Aldrich (St. Louis, Missouri) .sup.7An
alkoxy silane functional urethane resin prepared by reacting a
polyfunctional isocyanate trimer (52%), 1,4-butanediol (3.8%), and
n-butyl-3-aminopropyltrimethoxysilane (44.2%) (solids content).
[0077] A total of 8.4 grams of FMS-9922
polytrifluoropropylmethylsiloxane silanol terminated and 47.8 grams
of n-butyl acetate were added to a suitable reaction vessel
equipped with an air motor containing a cowles dispersing blade
first set at a 125 rpm. Nano-sized particles of TiO.sub.2-P25
aeroxide (13.04 grams) (from Evonik Industries (Essen, Germany) and
having a mean particle size which is 25 nm as reported by the
manufacturer) were slowly added to the reaction vessel over a time
of 15 minutes. The speed on the air motor was increased to 1600 rpm
and the particles were dispersed in the mixture for 30 minutes. The
speed of the air motor was set to 125 rpm after the 30 minutes and
2.0 grams of 3-aminopropyltriethoxysilane, 1.4 grams of zirconium
butoxide, 0.25 grams of dibutyltin diacetate, and 24.15 grams of an
alkoxy silane functional urethane were added to the mixture over 10
minutes and the mixture was allowed to stir for an additional 10
minutes at 125 rpm. This mixture was then spray-applied to
pre-treated (using X-Bond 4000 from PPG Industries, Inc.
(Pittsburgh, Pa.)) aluminum panels and allowed to cure at ambient
temperature for 24 hours. The coating thickness was approximately
0.3 mm. The panels were tested the next day for WCA and hysteresis
using the Kruss Drop Shape Analysis using the Kruss Drop Shape
Analyzer (DSA 100) according to ASTM test method D7334. The WCA for
this coating was 154.5.degree.. The hysteresis demonstrated by the
coating was 20.4.degree.. The coating was also tested for hardness
using a FISCHERSCOPE HM2000, a professional microhardness
measurement instrument for the analysis of mechanical and elastic
properties of materials by means of nanoindentation. The
microhardness of this coating was measured to be 104.6
N/mm.sup.2.
Example 2
Water Contact Angle for Room Temperature Cured Coating Composition
without Metal Alkoxide
[0078] A coating composition was prepared from the components
listed in Table 2.
TABLE-US-00002 TABLE 2 Weight Solution % on Component Weight Solids
solids FMS-9922 Polytrifluoropropylmethylsiloxane 15.4 15.4 41.3%
silanol terminated.sup.1 Nano TiO.sub.2-P25, Aeroxide.sup.2 12.6
12.6 33.8% 3-Aminopropyltriethoxysilane.sup.3 2.0 2.0 5.4% n-Butyl
acetate.sup.4 53 0 0.0% Dibutyltin diacetate.sup.5 0.25 0.25 0.7%
Alkoxy silane urethane.sup.6 12.07 7 18.8% 95.32 37.25 100.0%
.sup.1-6see Table 1.
[0079] A total of 15.4 grams of FMS-9922
polytrifluoropropylmethylsiloxane silanol terminated, and 53.0
grams of n-butyl acetate were added to a suitable reaction vessel
equipped with an air motor containing a cowles dispersing blade
first set at a 125 rpm. Nano-sized particles of TiO.sub.2-P25
aeroxide (12.6 grams) and having a mean particle size which is 25
nm according to ASTM F1877-16 were slowly added to the reaction
vessel over a time of 15 minutes. The speed on the air motor was
increased to 1600 rpm and the particles were dispersed in the
mixture for 30 minutes. The speed of the air motor was set to 125
rpm after the 30 minutes and 2.0 grams of
3-aminopropyltriethoxysilane, 0.25 grams of dibutyltin diacetate,
and 12.1 grams of an alkoxy silane functional urethane were added
to the mixture over 10 minutes and the mixture was allowed to stir
for an additional 10 minutes at 125 rpm. This mixture was then
spray-applied to pre-treated using X-Bond 4000 aluminum panels and
allowed to cure at ambient temperature for 24 hours. The coating
thickness was approximately 0.3 mm. The panels were tested the next
day for WCA and hysteresis using Kruss Drop Shape Analysis. The WCA
for this coating was 158.1.degree.. The hysteresis demonstrated by
the coating was 26.2.degree.. The coating was also tested for
hardness using a FISCHERSCOPE HM2000, a professional microhardness
measurement instrument for the analysis of mechanical and elastic
properties of materials by means of nanoindentation. The
microhardness of this coating was measured to be 16.1
N/mm.sup.2.
Example 3
Water Contact Angle for Room Temperature Cured Coating
Composition
[0080] A coating composition was prepared from the components
listed in Table 3.
TABLE-US-00003 TABLE 3 Weight Solution % on Component Weight Solids
solids FMS-9922 Polytrifluoropropylmethylsiloxane 9.8 9.8 22.8%
silanol terminated.sup.1 Nano TiO.sub.2-P25, Aeroxide.sup.2 12.9
12.9 30.0% 3-Aminopropyltriethoxysilane.sup.3 2.3 2.3 5.3% n-Butyl
acetate.sup.4 48.8 0.0 0.0% Zirconium butoxide.sup.5 1.4 1.4 3.2%
Dibutyltin diacetate.sup.6 0.26 0.26 0.6% Acrylic silane.sup.8
24.47 16.4 38.1% 99.93 43.2 100.0% .sup.1-6see Table 1. .sup.8A
silane functional acrylic resin prepared by reacting an acrylic
polyol (84%), trimethoxysilyl isocyanate functional silane (16%),
and vinyl trimethoxy silane (solids content).
[0081] A total of 9.8 grams of FMS-9922
polytrifluoropropylmethylsiloxane silanol terminated, and 48.8
grams of n-butyl acetate were added to a suitable reaction vessel
equipped with an air motor containing a cowles dispersing blade
first set at a 125 rpm. Nano-sized particles of TiO.sub.2-P25
aeroxide (12.9 grams) and having a mean particle size which is 25
nm according to ASTM F1877-16 were slowly added to the reaction
vessel over a time of 15 minutes. The speed on the air motor was
increased to 1600 rpm and the particles were dispersed in the
mixture for 30 minutes. The speed of the air motor was set to 125
rpm after the 30 minutes and 2.3 grams of
3-aminopropyltriethoxysilane, 1.4 grams of zirconium butoxide, 0.26
grams of dibutyltin diacetate, and 24.47 grams of a silane
functional acrylic were added to the mixture over 10 minutes and
the mixture was allowed to stir for an additional 10 minutes at 125
rpm. This mixture was then spray-applied to pre-treated using
X-Bond 4000 aluminum panels and allowed to cure at ambient
temperature for 24 hours. The coating thickness was approximately
0.3 mm. The panels were tested the next day for WCA and hysteresis
using Kruss Drop Shape Analysis. The WCA for this coating was
154.2.degree.. The hysteresis demonstrated by the coating was
1.8.degree.. Fischer microhardness for the fully cured coating was
measured at 92.04 N/mm.sup.2.
[0082] Whereas particular embodiments of this invention have been
described above for purposes of illustration, it will be evident to
those skilled in the art that numerous variations of the details of
the present invention may be made without departing from the
invention as defined in the appended claims.
* * * * *