U.S. patent application number 16/905403 was filed with the patent office on 2021-01-14 for curable film-forming sol-gel compositions and anti-glare coated articles formed from them.
The applicant listed for this patent is PPG Industries Ohio, Inc.. Invention is credited to Songwei Lu, David C. Martin, Kurt G. Olson, Irina Schwendeman, Shanti Swarup, Noel Vanier, Xiangling Xu.
Application Number | 20210009815 16/905403 |
Document ID | / |
Family ID | 1000005109478 |
Filed Date | 2021-01-14 |
United States Patent
Application |
20210009815 |
Kind Code |
A1 |
Lu; Songwei ; et
al. |
January 14, 2021 |
CURABLE FILM-FORMING SOL-GEL COMPOSITIONS AND ANTI-GLARE COATED
ARTICLES FORMED FROM THEM
Abstract
Curable film-forming sol-gel compositions that are essentially
free of inorganic oxide particles are provided. The compositions
contain: a tetraalkoxysilane; a solvent component; and non-oxide
particles, and further contain either i) a mineral acid or ii) an
epoxy functional trialkoxysilane and a metal-containing catalyst.
Coated articles demonstrating antiglare properties are also
provided, comprising: (a) a substrate having at least one surface;
and (b) a cured film-forming composition applied thereon, formed
from a curable sol-gel composition comprising a silane and
non-oxide particles. A method of forming an antiglare coating on a
substrate is also provided. The method comprises: (a) applying a
curable film-forming sol-gel composition on at least one surface of
the substrate to form a coated substrate; and (b) subjecting the
coated substrate to thermal conditions for a time sufficient to
effect cure of the sol-gel composition and form a coated substrate
with a sol-gel network layer having anti-glare properties.
Inventors: |
Lu; Songwei; (Wexford,
PA) ; Vanier; Noel; (Wexford, PA) ; Xu;
Xiangling; (Pittsburgh, PA) ; Swarup; Shanti;
(Allison Park, PA) ; Martin; David C.; (Bethel
Park, PA) ; Olson; Kurt G.; (Gibsonia, PA) ;
Schwendeman; Irina; (Wexford, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PPG Industries Ohio, Inc. |
Cleveland |
OH |
US |
|
|
Family ID: |
1000005109478 |
Appl. No.: |
16/905403 |
Filed: |
June 18, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14951541 |
Nov 25, 2015 |
10723890 |
|
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16905403 |
|
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62084170 |
Nov 25, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C09D 183/06 20130101;
C08G 77/02 20130101; C08K 3/28 20130101; B05D 3/0272 20130101; C09D
125/06 20130101; C03C 17/30 20130101; G02B 1/111 20130101; B05D
3/0236 20130101; B05D 5/061 20130101; G06F 3/0412 20130101; C03C
2218/32 20130101; C09D 5/006 20130101; C03C 2217/732 20130101; C08F
257/02 20130101; C03C 2217/29 20130101; C09D 183/02 20130101; C03C
2218/112 20130101; C08G 77/14 20130101; G06F 2203/04103 20130101;
C09D 183/04 20130101 |
International
Class: |
C09D 5/00 20060101
C09D005/00; C09D 125/06 20060101 C09D125/06; C09D 183/06 20060101
C09D183/06; C03C 17/30 20060101 C03C017/30; C08F 257/02 20060101
C08F257/02; C09D 183/02 20060101 C09D183/02; B05D 3/02 20060101
B05D003/02; B05D 5/06 20060101 B05D005/06; C09D 183/04 20060101
C09D183/04; G02B 1/111 20060101 G02B001/111; G06F 3/041 20060101
G06F003/041 |
Claims
1. A curable film-forming sol-gel composition that is essentially
free of inorganic oxide particles and comprises: (i) a
tetraalkoxysilane; (ii) a mineral acid; (iii) a solvent component;
and (iv) non-oxide particles.
2. The composition of claim 1 wherein the tetraalkoxysilane (i)
comprises tetramethoxysilane and/or tetraethoxysilane.
3. The composition of claim 1 wherein the mineral acid (ii)
comprises nitric acid or hydrochloric acid.
4. The composition of claim 1 wherein the non-oxide particles (iv)
comprise polystyrene, polyurethane, acrylic, alkyd, polyester,
polysulfide, polyepoxide, polyurea, polyolefin, and/or
silicone-containing rubber polymers, or are in the form of a latex
and comprise hollow-sphere acrylic polymeric particles and/or solid
polymeric particles.
5. A curable film-forming sol-gel composition that is essentially
free of inorganic oxide particles and comprises: (i) a
tetraalkoxysilane; (ii) an epoxy functional trialkoxysilane; (iii)
a metal-containing catalyst; (iv) a solvent component; and (v)
non-oxide particles.
6. The composition of claim 5 wherein the tetraalkoxysilane (i)
comprises tetramethoxysilane and/or tetraethoxysilane.
7. The composition of claim 5, wherein the epoxy functional
trialkoxysilane (ii) comprises glycidoxypropyl
trimethoxysilane.
8. The composition of claim 5 wherein the metal-containing catalyst
(iii) comprises colloidal aluminum hydroxychloride or aluminum
acetylacetonate.
9. The composition of claim 5 wherein the non-oxide particles (v)
are inorganic and comprise at least one of Si.sub.3N.sub.4, BN,
SiC, and ZnS.
10. The composition of claim 5 wherein the non-oxide particles (v)
comprise polystyrene, polyurethane, acrylic, alkyd, polyester,
polysulfide, polyepoxide, polyurea, polyolefin, and/or
silicone-containing rubber polymers, or are in the form of a latex
and comprise hollow-sphere acrylic polymeric particles and/or solid
polymeric particles.
11. A curable film-forming sol-gel composition that is essentially
free of inorganic oxide particles and comprises: (i) a
tetraalkoxysilane; (ii) a mineral acid; (iii) a solvent component;
and (iv) non-oxide particles; wherein the non-oxide particles are
selected from the group consisting of Si.sub.3N.sub.4; BN; SiC; Zn;
polystyrene; polyurethane; acrylic; alkyd; polyester; polysulfide;
polyepoxide; polyurea; polyolefin; silicone-containing rubber
polymers; sodium salts of 3-allyloxy-2-hydroxy-1-propanesulfonic
acid, 2-Acrylamido-2-methylpropane sulfonic acid, styrene sulfonic
acid, or (meth) acrylic acid; ammonium salts of
3-allyloxy-2-hydroxy-1-propanesulfonic acid,
2-Acrylamido-2-methylpropane sulfonic acid, styrene sulfonic acid,
or (meth) acrylic acid; Vinylbenzyltrimethyl ammonium chloride;
diallyldimethylammonium chloride; dimethylaminoethyl
(meth)acrylate; tert-butylaminoethyl methacrylate;
trimethyl(2-methacryloxylethyl) ammonium chloride;
dimethylaminopropyl (meth)acrylamide;
trimethyl(2-methacrylamidopropyl) ammonium chloride; and mixtures
thereof; wherein when the non-oxide particles are acrylic or
polystyrene polymers, they are added to the film-forming sol-gel
composition in the form of cationic or anionic aqueous dispersions
of acrylic or polystyrene polymer particles.
12. The composition of claim 11 wherein the tetraalkoxysilane (i)
comprises tetramethoxysilane and/or tetraethoxysilane.
13. The composition of claim 11 wherein the mineral acid (ii)
comprises nitric acid or hydrochloric acid.
14. A coated article demonstrating anti-glare properties, wherein
the coated article comprises: (a) a substrate having at least one
flat surface; and (b) a cured film-forming composition applied to
at least a portion of the flat surface of the substrate, wherein
the cured film-forming composition is formed from the curable
sol-gel composition of claim 11, and wherein the substrate
comprises soda-lime-silica glass, aluminosilicate glass, a polymer
prepared from polyol(allyl carbonate) monomers, a polymer prepared
from polyol(meth)acryloyl terminated carbonate monomer, or
thermoplastic polycarbonates; and wherein the coated article
demonstrates a 60.degree. gloss value of 15 to 120 gloss units and
a light transmittance of at least 84%.
15. The coated article of claim 14, wherein the coated article
comprises a lens.
16. A curable film-forming sol-gel composition that is essentially
free of inorganic oxide particles and comprises: (i) a
tetraalkoxysilane; (ii) an epoxy functional trialkoxysilane; (iii)
a metal-containing catalyst; (iv) a solvent component; and (v)
non-oxide particles; wherein the non-oxide particles are selected
from the group consisting of Si.sub.3N.sub.4; BN; SiC; Zn;
polystyrene; polyurethane; acrylic; alkyd; polyester; polysulfide;
polyepoxide; polyurea; polyolefin; silicone-containing rubber
polymers; sodium salts of 3-allyloxy-2-hydroxy-1-propanesulfonic
acid, 2-Acrylamido-2-methylpropane sulfonic acid, styrene sulfonic
acid, or (meth) acrylic acid; ammonium salts of
3-allyloxy-2-hydroxy-1-propanesulfonic acid,
2-Acrylamido-2-methylpropane sulfonic acid, styrene sulfonic acid,
or (meth) acrylic acid; Vinylbenzyltrimethyl ammonium chloride;
diallyldimethylammonium chloride; dimethylaminoethyl
(meth)acrylate; tert-butylaminoethyl methacrylate;
trimethyl(2-methacryloxylethyl) ammonium chloride;
dimethylaminopropyl (meth)acrylamide;
trimethyl(2-methacrylamidopropyl) ammonium chloride; and mixtures
thereof; wherein when the non-oxide particles are acrylic or
polystyrene polymers, they are added to the film-forming sol-gel
composition in the form of cationic or anionic aqueous dispersions
of acrylic or polystyrene polymer particles.
17. The composition of claim 16 wherein the tetraalkoxysilane (i)
comprises tetramethoxysilane and/or tetraethoxysilane.
18. The composition of claim 16, wherein the epoxy functional
trialkoxysilane (ii) comprises glycidoxypropyl
trimethoxysilane.
19. The composition of claim 16 wherein the metal-containing
catalyst (iii) comprises colloidal aluminum hydroxychloride or
aluminum acetylacetonate.
20. A coated article demonstrating anti-glare properties, wherein
the coated article comprises: (a) a substrate having at least one
flat surface; and (b) a cured film-forming composition applied to
at least a portion of the flat surface of the substrate, wherein
the cured film-forming composition is formed from the curable
sol-gel composition of claim 16, and wherein the substrate
comprises soda-lime-silica glass, aluminosilicate glass, a polymer
prepared from polyol(allyl carbonate) monomers, a polymer prepared
from polyol(meth)acryloyl terminated carbonate monomer, or
thermoplastic polycarbonates; and wherein the coated article
demonstrates a 60.degree. gloss value of 15 to 120 gloss units and
a light transmittance of at least 84%.
21. The coated article of claim 20, wherein the coated article
comprises a lens.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional of U.S. patent application
Ser. No. 14/951,541, filed Nov. 25, 2015, and entitled "CURABLE
FILM-FORMING SOL-GEL COMPOSITIONS AND ANTI-GLARE COATED ARTICLES
FORMED FROM THEM", which in turn claims priority from provisional
U.S. Patent Application Ser. No. 62/084,170, filed Nov. 25, 2014,
and entitled "ANTIGLARE COATED ARTICLES AND METHOD OF FORMING
ANTIGLARE TOUCH SCREEN DISPLAYS AND OTHER ANTIGLARE COATED
ARTICLES", both of which are incorporated herein by reference in
their entireties.
FIELD OF THE INVENTION
[0002] The present invention relates to curable film-forming
sol-gel compositions, coated articles demonstrating anti-glare
properties formed from these compositions, and methods of forming
anti-glare coatings on a substrate.
BACKGROUND OF THE INVENTION
[0003] Information displays such as touch screen displays appear
more and more frequently on interactive electronic devices.
Reducing glare of the screens, a brightness caused by the
reflection of incident light, is desired to maximize visibility of
the displays in different lighting environments. There are various
known methods of reducing the glare of transparent substrate
surfaces. An exemplary method involves depositing a light
interference coating stack on the substrate that reduces reflection
by exploiting the optical interference within adjacent thin films.
Such films usually have a thickness of about one-quarter or
one-half the nominal wavelength of visible light, depending on the
relative indices of refraction of the coatings and substrate.
Interference coatings reduce glare without reducing resolution.
However, they are relatively expensive to deposit, requiring the
use of vacuum deposition techniques such as sputtering and precise
manufacturing conditions, or very precise alkoxide solution dip
coating techniques, with subsequent drying and firing steps. Strict
processing parameters must be observed to obtain the desired
results.
[0004] Another method of reducing glare on displays involves
forming a light scattering means at the surface of the substrate,
such as by mechanically or chemically altering the outermost
surface of the substrate or through use of a diffuser coating or a
glare reducing film on the glass substrate.
[0005] Some antiglare coatings cause an undesirable visual
side-effect called visual sparkling effect, resulting from the
interaction of light from a regular display pixel matrix with
irregular microstructures present in the antiglare coating surface.
Most antiglare surfaces such as acid-etched antiglare surfaces have
a sparkling issue on high pixel per inch (PPI) displays.
[0006] Another option is the use of fillers. Fillers are widely
used in the coatings industry to affect gloss and they are known to
provide glare reduction to substrates in many cases. Fillers
control gloss by affecting the surface roughness of an applied
coating.
[0007] Etching the outer surface of the substrate or otherwise
chemically or mechanically modifying the outer surface of a coating
deposited on the substrate has also been attempted in an effort to
reduce glare by diffusive reflection of light. There are numerous
drawbacks to such modification techniques. Etching by chemical
means involves handling and storage of generally highly corrosive
compounds (e.g. hydrofluoric acid). Such compounds create
processing and disposal problems in view of increasingly stringent
environmental laws. Etching by non-chemical means, such as by
sandblasting, necessitates additional and costly processing
operations.
[0008] For touch screens such as those used on smart phones and
tablets, a durable, anti-smudge coating is desired to ensure the
cleanness and clarity of the touch screen surface. The anti-smudge
coating is also expected to have a very smooth, silky, and slippery
feel. Various super-hydrophobic coatings have demonstrated
different degrees of anti-smudge properties and slipperiness.
However, it is very difficult to achieve a better wear durability
as tested using #0000 steel wool after more than 6000 cycles, and a
coefficient of friction (COF) of .ltoreq.0.03.
[0009] It would be desirable to provide compositions that form an
antiglare coating on a substrate while avoiding the drawbacks of
the prior art, and to provide coated articles such as touch screen
displays that demonstrate superior properties, including
anti-glare.
SUMMARY OF THE INVENTION
[0010] A curable film-forming sol-gel composition that is
essentially free of inorganic oxide particles is provided. The
curable film-forming sol-gel composition comprises: (i) a
tetraalkoxysilane; (ii) a mineral acid; (iii) a solvent component;
and (iv) non-oxide particles.
[0011] A second curable film-forming sol-gel composition that is
essentially free of inorganic oxide particles is also provided. The
second curable film-forming sol-gel composition comprises: (i) a
tetraalkoxysilane; (ii) an epoxy functional trialkoxysilane; (iii)
a metal-containing catalyst; (iv) a solvent component; and (v)
non-oxide particles.
[0012] Coated articles demonstrating antiglare properties are also
provided, An exemplary coated article comprises: (a) a substrate
having at least one flat or curved surface; and (b) a cured
film-forming composition applied to at least a portion of the
surface of the substrate. The cured film-forming composition is
formed from a curable sol-gel composition comprising a silane and
non-oxide particles, the non-oxide particles have an average
particle size, agglomerated or monodispersed, of between 50 nm and
2.0 microns, and the coated article demonstrates a 60.degree. gloss
value of 15 to 120 gloss units and a light transmittance of at
least 84%.
[0013] A method of forming an antiglare coating on a substrate is
also provided by the present invention, and may be used to prepare
the coated articles above. The method comprises: (a) applying a
curable film-forming sol-gel composition on at least one surface of
the substrate to form a coated substrate; and (b) subjecting the
coated substrate to thermal conditions for a time sufficient to
effect cure of the sol-gel composition and form a coated substrate
with a sol-gel network layer having anti-glare properties. The
curable film-forming sol-gel composition is essentially free of
inorganic oxide particles and comprises a silane and non-oxide
particles. The non-oxide particles have an average particle size,
agglomerated or monodispersed, of between 50 nm and 2.0
microns.
DETAILED DESCRIPTION OF THE INVENTION
[0014] Other than in any operating examples, or where otherwise
indicated, all numbers expressing quantities of ingredients,
reaction conditions and so forth 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.
[0015] 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 contain certain errors necessarily resulting from the
standard deviation found in their respective testing
measurements.
[0016] 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.
[0017] As used in this specification and the appended claims, the
articles "a," "an," and "the" include plural referents unless
expressly and unequivocally limited to one referent.
[0018] The various examples of the present invention as presented
herein are each understood to be non-limiting with respect to the
scope of the invention.
[0019] As used in the following description and claims, the
following terms have the meanings indicated below:
[0020] By "polymer" is meant a polymer including homopolymers and
copolymers, and oligomers. By "composite material" is meant a
combination of two or more differing materials.
[0021] The term "curable", as used for example in connection with a
curable composition, means that the indicated composition is
polymerizable or cross linkable through functional groups such as
alkoxysilane and silanol groups, by means that include, but are not
limited to, thermal (including ambient cure), catalytic, electron
beam, chemical free-radical initiation, and/or photoinitiation such
as by exposure to ultraviolet light or other actinic radiation.
[0022] The term "cure", "cured" or similar terms, as used in
connection with a cured or curable composition, e.g., a "cured
composition" of some specific description, means that at least a
portion of any polymerizable and/or crosslinkable components that
form the curable composition is polymerized and/or crosslinked.
Additionally, curing of a composition refers to subjecting said
composition to curing conditions such as those listed above,
leading to the reaction of the reactive functional groups of the
composition. The term "at least partially cured" means subjecting
the composition to curing conditions, wherein reaction of at least
a portion of the reactive groups of the composition occurs. The
composition can also be subjected to curing conditions such that a
substantially complete cure is attained and wherein further curing
results in no significant further improvement in physical
properties, such as hardness.
[0023] The term "reactive" refers to a functional group such as an
alkoxysilane or silanol group, capable of undergoing a chemical
reaction with itself and/or other functional groups spontaneously
or upon the application of heat or in the presence of a catalyst or
by any other means known to those skilled in the art.
[0024] By "ambient conditions" is meant the condition of
surroundings without adjustment of the temperature, humidity or
pressure. For example, a composition that cures at ambient
temperature undergoes a thermosetting reaction without the aid of
heat or other energy, for example, without baking in an oven, use
of forced air, or the like. Usually ambient temperature ranges from
60 to 90.degree. F. 15.6 to 32.2.degree. C.), such as a typical
room temperature, 72.degree. F. (22.2.degree. C.).
[0025] The terms "on", "appended to", "affixed to", "bonded to",
"adhered to", or terms of like import means that the designated
item, e.g., a coating, film or layer, is either directly connected
to the object surface, or indirectly connected to the object
surface, e.g., through one or more other coatings, films or
layers.
[0026] The term "optical quality", as used for example in
connection with polymeric materials, e.g., a "resin of optical
quality" or "organic polymeric material of optical quality" means
that the indicated material, e.g., a polymeric material, resin, or
resin composition, is or forms a substrate, layer, film or coating
that can be used as an optical article, such a glazing, or in
combination with an optical article.
[0027] The term "rigid", as used for example in connection with an
optical substrate, means that the specified item is
self-supporting.
[0028] The term "optical substrate" means that the specified
substrate is suitable for use in an optical article. Optical
articles include, but are not limited to, lenses, optical layers,
e.g., optical resin layers, optical films and optical coatings, and
optical substrates having a light influencing property.
[0029] The term "transparent", as used for example in connection
with a substrate, film, material and/or coating, means that the
indicated substrate, coating, film and/or material has the property
of transmitting visible light without appreciable scattering so
that objects lying beyond are entirely visible.
[0030] By "essentially free" is meant that if a compound is present
in a composition, it is present incidentally in an amount less than
0.1 percent by weight, often less than 0.05 percent by weight or
less than 0.01 percent by weight, usually less than trace
amounts.
[0031] The present invention provides curable film-forming sol-gel
compositions. Sol-gels are dynamic systems wherein a solution
("sol") gradually evolves into a gel-like two-phase system
containing both a liquid phase and solid phase, whose morphologies
range from discrete particles to continuous polymer networks within
the continuous liquid phase.
[0032] An exemplary composition comprises (i) a silane, typically a
tetraalkoxysilane. Because of the sol-gel nature of the
composition, the alkoxysilanes, when used, are hydrolyzed and they
are partially condensed prior to curing of the layer. The
hydrolyzed tetraalkoxysilane in the sol-gel layer typically
comprises tetramethoxysilane and/or tetraethoxysilane. The
tetraalkoxysilane is typically present in the curable film-forming
composition in an amount of at least 1 percent by weight and less
than 40 percent, or often less than 35 percent, or more often less
than 30 percent by weight, based on the total weight of the curable
film-forming composition.
[0033] The curable film-forming composition further comprises (ii)
a mineral acid; i. e., an inorganic acid. Suitable mineral acids
include sulfuric acid, nitric acid, hydrochloric acid, and the
like. Nitric acid is most often used. The mineral acid is typically
present in an amount such that the weight ratio of mineral acid to
silane is greater than 0.001:1, typically greater than 0.01:1,
greater than 0.03:1, or greater than 0.05:1. The weight ratio of
mineral acid to silane is typically less than 0.12:1.
[0034] The curable film-forming composition additionally comprises
(iii) a solvent. The solvent component may include water and one or
more polar organic solvents. Suitable organic solvents typically
have hydroxyl functional (i. e., alcohol) and/or ether functional
groups. Examples include glycol ethers such as propylene glycol
methyl ether, propylene glycol methyl ether acetate, dipropylene
glycol monomethyl ether, and/or diethylene glycol monobutyl ether.
Lower alkyl alcohols (e. g., having less than six carbon atoms)
such as isopropanol and ethanol are also suitable.
[0035] The curable film-forming composition further comprises (iv)
non-oxide particles. The non-oxide particles may be organic or
inorganic. Suitable inorganic particles may include one or more of
Si.sub.3N.sub.4, BN, SiC, and ZnS. The non-oxide particles
typically have an average particle size, agglomerated or
monodispersed, of between 50 nm and 2.0 microns. When the particles
demonstrate an average particle size less than 1000 nm (i. e., less
than 1 micron), they would be considered nanoparticles. Particle
size may be determined from among the numerous techniques known in
the art, such as the method described below. The particle size may
be measured with a Malvern Zetasizer 3000HS, which is a high
performance two angle particle size analyzer for the enhanced
detection of aggregates and measurement of small or dilute samples,
and samples at very low or high concentration using dynamic light
scattering. Typical applications of dynamic light scattering are
the characterization of particles, emulsions or molecules, which
have been dispersed or dissolved in a liquid. The Brownian motion
of particles or molecules in suspension causes laser light to be
scattered at different intensities. Analysis of these intensity
fluctuations yields the velocity of the Brownian motion and hence
the particle size using the Stokes-Einstein relationship. The
reported particle sizes for all examples are the Z average mean
value.
[0036] Suitable organic particles include polymeric particles such
as solid, including core-shell type, and/or hollow-sphere polymeric
particles. Organic particles may comprise, for example,
polystyrene, polyurethane, acrylic, alkyd, polyester, polysulfide,
polyepoxide, polyurea, polyolefin, or silicone-containing rubber
polymers. The organic polymeric particles are often provided in the
form of a latex and the particles may, but do not necessarily, have
cationic or anionic charges. When the organic polymer particles are
in the form of a latex, the particles typically have an average
particle size, agglomerated or monodispersed, of between 300 and
500 nm. Exemplary polymeric latices are described in U.S. Pat. No.
8,710,146, incorporated herein by reference in its entirety and
described as follows:
[0037] Various compositions may be used for the particles in a
latex as described in U.S. Pat. No. 8,710,146, including organic
polymers such as polystyrene, polyurethane, acrylic polymers, alkyd
polymers, polyesters, siloxane-containing polymers, polysulfides,
and epoxy-containing polymers or semi-conductors such as cadmium.
Alternatively, the particles may have a core-shell structure where
the core can be produced from the same materials as the unitary
particles. The shell may be produced from the same polymers as the
core material, with the polymer of the particle shell differing
from the core material for a particular array of the core-shell
particles. The core material and the shell material have different
indices of refraction. In addition, the refractive index of the
shell may vary as a function of the shell thickness in the form of
a gradient of refractive index through the shell thickness. The
shell material is non-film-forming, whereby the shell material
remains in position surrounding each particle core without forming
a film of the shell material so that the core-shell particles
remain as discrete particles within the polymeric matrix.
[0038] Typically, the particles in a latex of U.S. Pat. No.
8,710,146, are generally spherical. For core-shell particles, the
diameter of the core may constitute 80 to 90% of the total particle
diameter or 85% of the total particle diameter with the shell
constituting the balance of the particle diameter and having a
radial thickness dimension. The particles with a unitary structure
(as opposed to core-shell) are produced in an emulsion
polymerization process, such as free radical initiated
polymerization, using an ionic monomer, yielding a dispersion of
polymeric particles.
[0039] Useful ionic monomers are those having a sufficient affinity
for the polymer particles to produce high surface charge on the
particles, such that they readily self-assemble into a periodic
array. The ionic monomer binds with the polymeric particles and
exhibits a charge, thereby producing charged particles. The ionic
monomer may be an ionic surfactant, but can be an ionic monomer
that is not a surfactant.
[0040] The ionic monomer has an affinity with the polymeric
particles such that at least 50% of the ionic monomer (in its
disassociated, ionic state) that is added to the emulsion
polymerization dispersion becomes bound to the particles.
Alternatively, at least 70% or at least 90% of the disassociated,
ionic monomer added to the dispersion is bound to the polymeric
particles. This high affinity of the ionic monomer for the
polymeric particles improves the efficiency with which the ionic
monomer is used in the emulsion polymerization. A high percentage
of the total ionic monomer added to the reaction mixture binds with
the polymeric particles and is demonstrative of a higher binding
efficiency of the ionic monomer. "Binds with", "bound to the
polymeric particles" and like terms, when used in reference to the
ionic monomer, means that the ionic monomer becomes covalently or
otherwise bound to the particle, and/or that the ionic monomer
itself becomes part of the polymer that comprises the particle. The
bound ionic polymer, regardless of how it's bound, remains
substantially attached to and/or part of the particle during
purification.
[0041] Sodium or ammonium salt of
3-allyloxy-2-hydroxy-1-propanesulfonic acid (COPS-1),
2-Acrylamido-2-methylpropane sulfonic acid, styrene sulfonic acid,
and (meth) acrylic acid have commonly been used to prepare
negatively charged particles. Vinylbenzyltrimethyl ammonium
chloride, diallyldimethylammonium chloride, dimethylaminoethyl
(meth)acrylate, tert-butylaminoethyl methacrylate,
trimethyl(2-methacryloxylethyl) ammonium chloride,
dimethylaminopropyl (meth)acrylamide, and
trimethyl(2-methacrylamidopropyl) ammonium chloride have commonly
been used to prepare positively charged particles.
[0042] Particularly useful ionic monomers are those that are
minimally soluble in the dispersing fluid (e.g., water) of the
particle dispersion.
[0043] Core-shell particles are produced by dispersing core
monomers with initiators in solution to produce core particles.
Shell monomers are added to the core particle dispersion, along
with an ionic monomer (as described above for unitary particles),
such that the shell monomers polymerize onto the core particles.
The core-shell particles are purified from the dispersion by
similar means as described above to produce a dispersion of only
the charged particles, which then form an ordered array on a
substrate when applied thereto."
[0044] Particularly suitable organic non-oxide particles for use in
the compositions of the present invention include cationic or
anionic latex dispersions of acrylic and/or polystyrene polymer
particles, prepared from ethylenically unsaturated monomers such as
one or more of styrene, (meth) acrylates and vinyl acetate. These
latex dispersions of polymer particles may be prepared as described
in the Examples below.
[0045] The non-oxide particles are typically present in the curable
film-forming composition in an amount of at least 0.05 percent by
weight and less than 20 percent, or often less than 10 percent, or
more often less than 5 percent by weight, based on the total weight
of the curable film-forming composition.
[0046] The present invention also provides a second curable
film-forming sol-gel composition that is essentially free of
inorganic oxide particles is also provided. The second curable
film-forming sol-gel composition comprises: (i) a
tetraalkoxysilane; (ii) an epoxy functional trialkoxysilane; (iii)
a metal-containing catalyst; (iv) a solvent component; and (v)
non-oxide particles.
[0047] The tetraalkoxysilane (i) may be any of those disclosed
herein. The tetraalkoxysilane is typically present in the curable
film-forming composition in an amount of at least 1 percent by
weight and less than 20 percent, or often less than 15 percent, or
more often less than 10 percent by weight, based on the total
weight of the curable film-forming composition.
[0048] The second curable film-forming sol-gel composition further
comprises (ii) an epoxy functional trialkoxysilane, such as
3-glycidoxypropyl trimethoxysilane, and
3-(Glycidoxypropyl)triethoxysilane. The epoxy functional
trialkoxysilane may be partially hydrolyzed with water. The epoxy
functional trialkoxysilane is typically present in the curable
film-forming composition in an amount of at least 1 percent by
weight and less than 60 percent, or often less than 50 percent, or
more often less than 40 percent by weight, based on the total
weight of the curable film-forming composition.
[0049] The second curable film-forming sol-gel composition
additionally comprises (iii) a metal-containing catalyst, such as
an aluminum-containing catalyst. Examples include aluminum
hydroxychloride or aluminum acetylacetonate. Colloidal aluminum
hydroxychloride catalysts are available from Summit Reheis as
SUMALCHLOR 50 and from NALCO as NALCO 8676. The catalyst (iii) is
typically present in the curable film-forming composition in an
amount of at least 1 percent by weight and less than 35 percent, or
often less than 30 percent, or more often less than 25 percent by
weight, based on the total weight of the curable film-forming
composition.
[0050] The second curable film-forming sol-gel composition also
comprises (iv) a solvent component. The solvent component may
include water and one or more polar organic solvents, including
ethers such as cyclic ethers, glycol ethers, alcohols having 1 to 6
carbon atoms, such as methanol, ethanol, n-propanol, isopropanol,
n-butanol, and the like. Glycol ethers such as propylene glycol
methyl ether, propylene glycol methyl ether acetate, dipropylene
glycol monomethyl ether, and/or diethylene glycol monobutyl ether
are particularly suitable. The solvent (iv) is typically present in
the curable film-forming composition in an amount of at least 10
percent by weight and less than 80 percent, or often less than 70
percent, or more often less than 60 percent by weight, based on the
total weight of the curable film-forming composition.
[0051] The second curable film-forming sol-gel composition also
comprises (v) non-oxide particles. The non-oxides particles (v) may
be any of those disclosed herein. The particles are typically
present in the curable film-forming composition in an amount of at
least 0.05 percent by weight and less than 20 percent, or often
less than 10 percent, or more often less than 5 percent by weight,
based on the total weight of the curable film-forming
composition.
[0052] Each of the curable film-forming compositions described
herein can include a variety of optional ingredients and/or
additives that are somewhat dependent on the particular application
of the final coated article. For example, the composition may
exhibit a light influencing property. Other optional ingredients
include rheology control agents, surfactants, initiators,
catalysts, cure-inhibiting agents, reducing agents, acids, bases,
preservatives, free radical donors, free radical scavengers and
thermal stabilizers, which adjuvant materials are known to those
skilled in the art.
[0053] The curable film-forming compositions may include a
colorant, although typically the compositions are colorless and
transparent. They are also usually optically clear.
[0054] As used herein, the term "colorant" means any substance that
imparts color and/or other visual effect to the composition. The
colorant can be added to the coating in any suitable form, such as
discrete particles, dispersions, solutions and/or flakes. A single
colorant or a mixture of two or more colorants can be used in the
coatings of the present invention.
[0055] Example colorants include pigments, dyes and tints, such as
those used in the paint industry and/or listed in the Dry Color
Manufacturers Association (DCMA), as well as special effect
compositions. A colorant may include, for example, a finely divided
solid powder that is insoluble but wettable under the conditions of
use. A colorant can be organic or inorganic and can be agglomerated
or non-agglomerated. Colorants can be incorporated into the
coatings by grinding or simple mixing. Colorants can be
incorporated by grinding into the coating by use of a grind
vehicle, such as an acrylic grind vehicle, the use of which will be
familiar to one skilled in the art.
[0056] Example pigments and/or pigment compositions include, but
are not limited to, carbazole dioxazine crude pigment, azo,
monoazo, disazo, naphthol AS, salt type (lakes), benzimidazolone,
condensation, metal complex, isoindolinone, isoindoline and
polycyclic phthalocyanine, quinacridone, perylene, perinone,
diketopyrrolo pyrrole, thioindigo, anthraquinone, indanthrone,
anthrapyrimidine, flavanthrone, pyranthrone, anthanthrone,
dioxazine, triarylcarbonium, quinophthalone pigments, diketo
pyrrolo pyrrole red ("DPPBO red"), carbon black and mixtures
thereof. The terms "pigment" and "colored filler" can be used
interchangeably. Inorganic oxide pigments are typically not
used.
[0057] Example dyes include, but are not limited to, those that are
solvent and/or aqueous based such as acid dyes, azoic dyes, basic
dyes, direct dyes, disperse dyes, reactive dyes, solvent dyes,
sulfur dyes, mordant dyes, for example, bismuth vanadate,
anthraquinone, perylene, aluminum, quinacridone, thiazole,
thiazine, azo, indigoid, nitro, nitroso, oxazine, phthalocyanine,
quinoline, stilbene, quinizarin blue (D&C violet No. 2), and
triphenyl methane.
[0058] Example tints include, but are not limited to, pigments
dispersed in water-based or water miscible carriers such as
AQUA-CHEM 896 commercially available from Degussa, Inc., CHARISMA
COLORANTS and MAXITONER INDUSTRIAL COLORANTS commercially available
from Accurate Dispersions division of Eastman Chemical, Inc.
[0059] As noted above, the colorant can be in the form of a
dispersion including, but not limited to, a nanoparticle
dispersion. Nanoparticle dispersions can include one or more highly
dispersed nanoparticle colorants and/or colorant particles that
produce a desired visible color and/or opacity and/or visual
effect. Nanoparticle dispersions can include colorants such as
pigments or dyes having a particle size of less than 150 nm, such
as less than 70 nm, or less than 30 nm. Nanoparticles can be
produced by milling stock organic or inorganic pigments with
grinding media having a particle size of less than 0.5 mm. Example
nanoparticle dispersions and methods for making them are identified
in U.S. Pat. No. 6,875,800 B2 and United States Patent Application
Publication Number 20050287354. Nanoparticle dispersions can also
be produced by crystallization, precipitation, gas phase
condensation, and chemical attrition (i.e., partial dissolution).
In order to minimize re-agglomeration of nanoparticles within the
coating, a dispersion of resin-coated nanoparticles can be used. As
used herein, a "dispersion of resin-coated nanoparticles" refers to
a continuous phase in which is dispersed discreet "composite
microparticles" that comprise a nanoparticle and a resin coating on
the nanoparticle.
[0060] Dispersions of non-hiding, color-imparting organic pigment
nanoparticles offer particularly useful aesthetic properties in the
electronics industry. Such pigment dispersions are available from
PPG Industries, Inc. under the trademark ANDARO. Low levels of blue
nanopigments can offset any yellowing that may occur during curing
of film-forming compositions. Blue or black nanopigments enhance
the appearance of the anti-glare coating, particularly over black
underlayers on a substrate. Moreover, colored nanopigments may be
chosen to enhance or complement the underlying color of the
substrate, such as if the substrate is a colored housing for a cell
phone or tablet. Nanoparticle dispersion are particularly suitable
for use in curable film-forming sol-gel compositions of the present
invention that comprise (i) a tetraalkoxysilane; (ii) an epoxy
functional trialkoxysilane; (iii) a metal-containing catalyst; (iv)
a solvent component; and (v) non-oxide particles, as described
herein.
[0061] In general, the colorant can be present in the coating
composition in any amount sufficient to impart the desired
property, visual and/or color effect. The colorant may be present
in an amount from 1 to 65 weight percent of the present
compositions, such as from 3 to 40 weight percent or 5 to 35 weight
percent, with weight percent based on the total weight of the
compositions.
[0062] The curable film-forming compositions of the present
invention typically have a solids content of 0.1 to 10 percent by
weight, often 0.5 to 10 percent by weight, more often 1 to 8
percent by weight, usually less than 7 percent by weight or less
than 5 percent by weight, based on the total weight of the curable
film-forming composition.
[0063] The curable film-forming compositions of the present
invention may be prepared as described in the Examples herein.
[0064] The present invention is also drawn to coated articles
demonstrating antiglare properties. An exemplary coated article
comprises: (a) a substrate having at least one surface; and (b) a
cured film-forming composition applied to at least a portion of the
surface of the substrate. The cured film-forming composition is
formed from a curable sol-gel composition comprising a silane and
non-oxide particles, the non-oxide particles have an average
particle size, agglomerated or monodispersed, of between 50 nm and
2.0 microns, and the coated article demonstrates a 60.degree. gloss
value of 15 to 120 gloss units and a light transmittance of at
least 84%.
[0065] Substrates suitable for use in the preparation of the coated
articles (such as touch screen displays) of the present invention
can include glass or any of the plastic optical substrates known in
the art, provided the material can withstand temperatures of at
least 100.degree. F. without deformation. Metals may also be used
as substrates for the coated articles of the present invention. The
substrates have at least one flat surface.
[0066] Suitable metal substrates include substrates made of, for
example, highly polished stainless steel or other steel alloy,
aluminum, or titanium. A polished metal substrate typically has a
reflective surface. For example, the curable film-forming sol-gel
composition may be deposited over a surface comprising a reflective
material such as a polished metal, having a total reflectance of at
least 30%, such as at least 40%. "Total reflectance" refers herein
to the ratio of reflected light from an object relative to the
incident light that impinges on the object in the visible spectrum
integrating over all viewing angles. "Visible spectrum" refers
herein to that portion of the electromagnetic spectrum between
wavelengths 400 and 700 nanometers. "Viewing angle" refers herein
to the angle between the viewing ray and a normal to the surface at
the point of incidence. The reflectance values described herein may
be determined using a Minolta Spectrophotometer CM-3600d or X-Rite
i7 Color Spectrophotometer from X-Rite.
[0067] Aesthetically pleasing designs and effects may be achieved
on a polished metal reflective surface by applying the curable
film-forming sol-gel composition to portions of the surface, for
example, in a visual pattern, or on the entire surface of the
reflective substrate.
[0068] Suitable glass substrates include soda-lime-silica glass,
such as soda-lime-silica slide glass sold from Fisher, or
aluminosilicate glass such as Gorilla.RTM. glass from Corning
Incorporated, or Dragontrail.RTM. glass from Asahi Glass Co., Ltd.
In the present invention, the substrate is usually transparent
and/or has at least one flat surface. Suitable examples of plastic
substrates include polymers prepared from polyol(allyl carbonate)
monomers, e.g., allyl diglycol carbonates such as diethylene glycol
bis(allyl carbonate), which monomer is sold under the trademark
CR-39 by PPG Industries, Inc.; polyurea-polyurethane (polyurea
urethane) polymers, which are prepared, for example, by the
reaction of a polyurethane prepolymer and a diamine curing agent, a
composition for one such polymer being sold under the trademark
TRIVEX.RTM. by PPG Industries, Inc.; polymers prepared from
polyol(meth)acryloyl terminated carbonate monomer, diethylene
glycol dimethacrylate monomers, ethoxylated phenol methacrylate
monomers, diisopropenyl benzene monomers, ethoxylated trimethylol
propane triacrylate monomers, ethylene glycol bismethacrylate
monomers, poly(ethylene glycol) bismethacrylate monomers, or
urethane acrylate monomers; poly(ethoxylated Bisphenol A
dimethacrylate); poly(vinyl acetate); poly(vinyl alcohol);
poly(vinyl chloride); poly(vinylidene chloride); polyethylene;
polypropylene; polyurethanes; polythiourethanes; thermoplastic
polycarbonates, such as the carbonate-linked resin derived from
Bisphenol A and phosgene, one such material being sold under the
trademark LEXAN; polyesters, such as the material sold under the
trademark MYLAR; poly(ethylene terephthalate); polyvinyl butyral;
poly(methyl methacrylate), such as the material sold under the
trademark PLEXIGLAS, and polymers prepared by reacting
polyfunctional isocyanates with polythiols or polyepisulfide
monomers, either homopolymerized or co-and/or terpolymerized with
polythiols, polyisocyanates, polyisothiocyanates and optionally
ethylenically unsaturated monomers or halogenated
aromatic-containing vinyl monomers. Also suitable are copolymers of
such monomers and blends of the described polymers and copolymers
with other polymers, e.g., to form interpenetrating network
products.
[0069] The cured film-forming composition (b) applied to at least a
portion of the surface of the substrate (a) may be formed from any
of the curable film-forming sol-gel compositions described herein;
for example, the curable film-forming sol-gel composition may
comprise either (A): (i) a tetraalkoxysilane; (ii) an epoxy
functional trialkoxysilane; (iii) a metal-containing catalyst; (iv)
a solvent component; and (v) non-oxide nanoparticles; or (B): (i) a
tetraalkoxysilane; (ii) a mineral acid; (iii) a solvent component;
and (iv) non-oxide particles.
[0070] An exemplary coated article according to the present
invention demonstrates antiglare properties, and may comprise:
[0071] (a) a substrate; and
[0072] (b) a cured sol-gel layer applied on at least one surface of
the substrate to form a coated substrate; wherein the sol-gel layer
is deposited from a curable film-forming composition
comprising:
[0073] (i) a silane such as a tetraalkoxysilane present in an
amount less than less than 40 percent, or often less than 35
percent, or more often less than 30 percent by weight, based on the
total weight of the curable film-forming composition;
[0074] (ii) a mineral acid present in an amount wherein the weight
ratio of mineral acid to silane is greater than 0.001:1;
[0075] (iii) a solvent; and
[0076] (iv) non-oxide particles, wherein the curable film-forming
composition has a solids content less than 15 percent by
weight.
[0077] Coated articles of the present invention may comprise an
optical article. Optical articles of the present invention include
a display element such as screens, including touch screens, on
devices including cell phones, tablets, GPS, voting machines, POS
(Point-Of-Sale), or computer screens; display sheets in a picture
frame; windows, or an active or passive liquid crystal cell element
or device, and the like.
[0078] The present invention also provides a method of forming an
anti-glare coating on a substrate. This method may be used to
prepare the coated articles of the present invention that are
described herein. Suitable substrates for use in the method of the
present invention include any of those described herein. Typically
the substrate comprises a plastic, glass, or metal. The method
comprises: (a) applying a curable film-forming sol-gel composition
on at least one surface of the substrate to form a coated
substrate; and (b) subjecting the coated substrate to thermal
conditions for a time sufficient to effect cure of the sol-gel
composition and form a coated substrate with a sol-gel network
layer having anti-glare properties. The curable film-forming
sol-gel composition is essentially free of inorganic oxide
particles and comprises a silane and non-oxide particles. The
non-oxide particles have an average particle size, agglomerated or
monodispersed, of between 50 nm and 2.0 microns.
[0079] In the first step (a) of the method of the present
invention, a curable film-forming sol-gel composition is applied to
at least one surface of the substrate to form a coated substrate.
The curable film-forming sol-gel composition may be any of the
compositions of the present invention disclosed herein. For
example, the curable film-forming sol-gel composition may comprise
(A): (i) a tetraalkoxysilane; (ii) an epoxy functional
trialkoxysilane; (iii) a metal-containing catalyst; (iv) a solvent
component; and (v) non-oxide nanoparticles; or (B): (i) a
tetraalkoxysilane; (ii) a mineral acid; (iii) a solvent component;
and (iv) non-oxide particles.
[0080] The curable film-forming composition may be applied to the
substrate by one or more of a number of methods such as spraying,
dipping (immersion), spin coating, or flow coating onto a surface
thereof. Spraying is used most often, such as ultrasonic spray
application, precision spray application, and air atomized spray
application. The curable film-forming composition and the substrate
may be kept at ambient temperature immediately prior to
application. The applied sol-gel layer typically has a dry film
thickness of less than 10 microns, often less than 5 microns, or
less than 3 microns.
[0081] The sol-gel composition may be applied to the substrate
surface in such a manner as to yield a coated article with a
gradient gloss across its surface; i. e., a surface with a
gradually increasing gloss across a selected region, an effect
achieved by gradually decreasing the thickness of the applied
sol-gel composition coating layer across the substrate surface. As
the thickness of the coating layer decreases, the gloss across the
substrate surface increases, creating a visual effect. In the
method of the present invention, spray application of the sol-gel
composition is used to prepare a coated article with a gradient
gloss. Rather than evenly spray-applying the composition over the
entire surface of the substrate to form a coating layer with a
consistent thickness, the spray nozzle may be held stationary over
a selected point on the substrate or may make one or more passes
over a selected region of the substrate. The thickness of the
applied coating decreases with distance from the spray nozzle. The
effect may also be achieved using a spray nozzle with graduated
flow rates.
[0082] In step (b) of the method of the present invention, after
application of the sol-gel layer, the coated substrate is then
subjected to thermal conditions for a time sufficient to effect
cure of the sol-gel layer and form an antiglare coated article. For
example, the coated substrate may be heated to a temperature of at
least 80.degree. C. for at least 10 minutes, to promote the
continued polymerization of the composition. In particular
examples, the coated substrate may be heated to a temperature of
120.degree. C. for at least 3 hours, or the coated substrate may be
heated to a temperature of at least 150.degree. C. for at least 1
hour.
[0083] The sol-gel composition forms a matte finish (low gloss),
antiglare coating on the substrate. Coated articles of the present
invention formed by the method described above typically
demonstrate a minimum 60.degree. gloss value of 15 or 20 or 50
gloss units, and a maximum 60.degree. gloss value of 100 or 120
gloss units, as measured by a micro-TRI-gloss meter from
BYK-Gardner GmbH. Coated articles of the present invention
demonstrate reduced glare (direct reflection of incident light)
without reducing resolution of a display viewed through the
article. This is particularly advantageous when the coated article
is an optical article such as a screen, in particular, a touch
screen, for an electronic device such as a phone, monitor, tablet,
or the like.
[0084] The sol-gel network layer that is formed on the substrate in
the method of the present invention comprises a hybrid
"inorganic-organic" network; i. e., the network layer comprises
both inorganic and organic structural groups on the molecular
level. This allows for some variability in design with respect to
mechanical properties of the sol-gel layer, such as
flexibility.
[0085] At least one additional coating composition may be applied
to the coated article after step (b). For example, an anti-fouling
coating, anti-smudge coating, and/or sealant layer may be
superimposed on at least one surface of the sol-gel layer.
Anti-smudge coatings typically demonstrate a DI water contact angle
greater than 100.degree.. Suitable sealant layers may comprise
perfluorosilane.
[0086] Each of the aspects and characteristics described above, and
combinations thereof, may be said to be encompassed by the present
invention. For example, the present invention is thus drawn to the
following nonlimiting aspects:
[0087] 1. A curable film-forming sol-gel composition that is
essentially free of inorganic oxide particles and comprises:
[0088] (i) a tetraalkoxysilane;
[0089] (ii) a mineral acid;
[0090] (iii) a solvent component; and
[0091] (iv) non-oxide particles.
[0092] 2. A curable film-forming sol-gel composition that is
essentially free of inorganic oxide particles and comprises:
[0093] (i) a tetraalkoxysilane;
[0094] (ii) an epoxy functional trialkoxysilane;
[0095] (iii) a metal-containing catalyst;
[0096] (iv) a solvent component; and
[0097] (v) non-oxide particles.
[0098] 3. The composition according to any one of aspect 1 or
aspect 2, wherein the tetraalkoxysilane (i) comprises
tetramethoxysilane and/or tetraethoxysilane.
[0099] 4. The composition according to aspect 1 wherein the mineral
acid (ii) comprises nitric acid or hydrochloric acid.
[0100] 5. The composition according to any one of aspects 1 to 4
wherein the non-oxide particles are in the form of a latex and
comprise hollow-sphere acrylic polymeric particles and/or solid
polymeric particles.
[0101] 6. The composition according to any one of aspects 2, 3, or
5, wherein the epoxy functional trialkoxysilane (ii) comprises
glycidoxypropyl trimethoxysilane.
[0102] 7. The composition according to any one of aspects 2, 3, 5
or 6, wherein the metal-containing catalyst (iii) comprises
colloidal aluminum hydroxychloride or aluminum acetylacetonate.
[0103] 8. The composition according to any one of aspects 1 to 7,
wherein the non-oxide particles are inorganic and comprise at least
one of Si.sub.3N.sub.4, BN, SiC, and ZnS.
[0104] 9. A coated article demonstrating anti-glare properties,
wherein the coated article comprises:
[0105] (a) a substrate having at least one surface; and
[0106] (b) a cured film-forming composition applied to at least a
portion of the surface of the substrate, wherein the cured
film-forming composition is formed from a curable sol-gel
composition comprising a silane and non-oxide particles, the
non-oxide particles have an average particle size, agglomerated or
monodispersed, of between 50 nm and 2.0 microns, and the coated
article demonstrates a 60.degree. gloss value of 15 to 120 gloss
units and a light transmittance of at least 84%.
[0107] 10. The coated article according to aspect 9, wherein the
curable film-forming sol-gel composition comprises any of those
according to aspects 1 to 8.
[0108] 11. The coated article according to either of aspects 9 and
10, wherein the article comprises a window, touch screen, cell
phone screen, tablet screen, GPS screen, voting machine screen, POS
(Point-Of-Sale) screen, computer screen, display sheet in a picture
frame, or an active or passive liquid crystal cell element or
device.
[0109] 12. A method of forming an anti-glare coating on a substrate
comprising: [0110] (a) applying a curable film-forming sol-gel
composition on at least one surface of the substrate to form a
coated substrate, wherein the curable film-forming sol-gel
composition is essentially free of inorganic oxide particles and
comprises a silane and non-oxide particles, the non-oxide particles
have an average particle size, agglomerated or monodispersed, of
between 50 nm and 2.0 microns; and
[0111] (b) subjecting the coated substrate to thermal conditions
for a time sufficient to effect cure of the sol-gel composition and
form a coated substrate with a sol-gel network layer having
anti-glare properties.
[0112] 13. The method according to aspect 12 wherein the substrate
comprises a plastic, glass, or metal.
[0113] 14. The method according to any of aspects 12 and 13,
wherein, immediately prior to application to the substrate, the
substrate and the curable film-forming composition are kept at
ambient temperature.
[0114] 15. The method according to any of aspects 12 to 14, wherein
the curable film-forming sol-gel composition comprises any of those
according to aspects 1 to 8.
[0115] 16. The method according to any of aspects 12 to 15, wherein
the curable film-forming sol-gel composition is spray applied or
spin coated onto the substrate in step (a).
[0116] 17. The method according to any of aspects 12 to 16, wherein
the coated substrate is heated to a temperature of at least
80.degree. C. for at least 10 minutes in step (b).
[0117] 18. The method according to any of aspects 12 to 17, wherein
the coated article formed in step (b) demonstrates a 60.degree.
gloss value of 15 gloss units to 120 gloss units.
[0118] The following examples are intended to illustrate various
aspects of the invention, and should not be construed as limiting
the invention in any way.
EXAMPLES
Example 1
[0119] A dispersion of anionic polystyrene particles in water was
prepared via the following procedure. 5.5 g of sodium bicarbonate
from Aldrich Chemical Company, Inc., 2.5 g Sipomer PAM 200 from
Rhodia, and 4.5 g CD552 (Methoxy polyethylene glycol (550)
monomethacrylate) from Sartomer, 0.10 g sodium styrene sulfonate
(SSS) from Aldrich Chemical Company, Inc., were mixed with 2260 g
deionized water and added to flask equipped with a thermocouple,
heating mantle, stirrer, reflux condenser and nitrogen blanket. The
mixture was heated to 50.degree. C. After that, mixture of 125 g
Styrene monomer was charged. The mixture was then heated to
70.degree. C. and held for 30 minutes. Next, sodium persulfate from
the Aldrich Chemical Company, Inc. (9.6 g in 70 g deionized water)
was added to the mixture under stirring. The temperature of the
mixture was maintained at 70.degree. C. for approximately 2 hours.
Following that, a preemulsified mixture of 340 g deionized water,
6.0 g Reasoap SR-10 form Adeak, 420 g styrene, 1.2 g SSS, and 0.5 g
sodium persulfate was divided into 3 parts, and charged into flask
at 45 mins interval. Following that, a preemulsified mixture of 240
g deionized water, 3.0 g Reasoap SR-10 form Adeak, 135 g styrene,
135 g methyl methacrylate, 9.0 g ethylene glycol dimethacrylate,
1.2 g SSS, and 0.5 g sodium persulfate was divided into 2 parts,
and charged into flask at 45 mins interval. The temperature of the
mixture was hold at 70.degree. C. for additional 2 hours to
complete polymerization. The resulting dispersion was filtered
through a one-micron filter bag. The volume average particle
diameter was measured to be 240 nm by Zetasizer 3000HS.
Example 2
[0120] A dispersion of cationic polystyrene particles in water was
prepared via the following procedure. 7.2 g Brij 35 from Aldrich,
7.2 g CD552 (Methoxy polyethylene glycol (550) monomethacrylate)
from Sartomer, 3.6 g Dodecyltrimethyl ammonium chloride from
Aldrich, and 6.0 g acetic acid were mixed with 3240 g deionized
water and added to flask equipped with a thermocouple, heating
mantle, stirrer, reflux condenser and nitrogen blanket. The mixture
was first heated to 50.degree. C., and then a mixture of 360 g
styrene and 25 g methyl methacrylate monomer was charged. The
mixture was then heated to 70.degree. C. and held for 30 minutes.
Next, azo-bis(methylpropionamide) dihydrochloride from the Aldrich
Chemical Company, Inc. (9 g in 144 g deionized water) was added to
the mixture under stirring. The temperature of the mixture was
maintained at 70.degree. C. for approximately 3 hours. Following
that, a preemulsified mixture of 2500 g deionized water, 36 g Brij
35, 1080 g styrene, 32.4 g Dimethylaminoethyl methacrylate, 10.8 g
acetic acid and 36 g CD552 was charged into flask over 90 minutes.
After 30 minute holding, a mixture of 3.0 g t-butylhydroperoxide
and 15 g deionized water was charged to flask. After that, a
mixture of 1.50 g ascorbic acid and 40 g deionized water was
charged over 15 minutes. The reaction was held at 70.degree. C. for
additional 1 hr. The resulting dispersion was filtered through a
one-micron filter bag. The volume average particle diameter was
measured to be 304 nm by Zetasizer 3000HS.
Example 3
[0121] In a vessel with a magnetic stir bar, 30.0 grams of
tetraethyl orthosilica from the Sigma-Aldrich Corporation, 17.5
grams deionized water and 17.5 grams denatured ethyl alcohol were
added and the solution was stirred on a magnetic stirrer for 10
min. During agitation, 1.8 grams of 4.68 wt % aqueous nitric acid
was added to the above mixture. Thereafter the solution is stirred
for 1 hour. Then, an additional 29.2 grams of denatured ethyl
alcohol and 4.0 grams of polystyrene particles in water of Example
1 were added to the solution, which is stirred for 10 min.
[0122] Glass substrates (2.times.''.times.3''.times.1 mm microscope
slide glass purchased from Fisher Scientific) were pre-treated with
a low pressure plasma system from Diener Electronics, Germany. The
coating solutions were then sprayed on the glass substrates with a
substrate temperature at room temperature using a SPRAYMATION and a
Binks 95 automatic HVLP spray gun with a traverse speed of 600
inch/min. Four specimens of each example were prepared. The coated
glass samples were then cured at 150.degree. C. for 60 min.
[0123] Gloss, L*, a*, b*, Haze, T % at 550 nm, R.sub.a, and pencil
hardness were measured on these samples and were recorded in Table
1.
Example 4
[0124] In a vessel with a magnetic stir bar, 30.0 grams of
tetraethyl orthosilica from the Sigma-Aldrich Corporation, 17.5
grams deionized water and 17.5 grams denatured ethyl alcohol were
added and the solution was stirred on a magnetic stirrer for 10
min. During agitation, 1.8 grams of 4.68 wt % aqueous nitric acid
was added to the above mixture. Thereafter the solution is stirred
for 1 hour. Then, an additional 29.2 grams of denatured ethyl
alcohol and 4.0 grams of polystyrene particles in water of Example
2 were added to the solution, which is stirred for 10 min.
[0125] Glass substrates (2.times.''.times.3''.times.1 mm microscope
slide glass purchased from Fisher Scientific) were pre-treated with
a low pressure plasma system from Diener Electronics, Germany. The
coating solutions were then sprayed on the glass substrates with a
substrate temperature at room temperature using a SPRAYMATION and a
Binks 95 automatic HVLP spray gun with a traverse speed of 600
inch/min. Four specimens of each example were prepared. The coated
glass samples were then cured at 150.degree. C. for 60 min.
[0126] Gloss, L*, a*, b*, Haze, T % at 550 nm, R.sub.a, and pencil
hardness were measured on these samples and were recorded in Table
1. Gloss is measured using a gloss meter, such as the
micro-TRI-gloss meter, which directs a light at a specific angle to
the test surface and simultaneously measures the amount of
reflection. The 60.degree. gloss is measured at an incident angle
of 60.degree.. A matte black background with a gloss value of
<0.5 GU is placed under the transparent substrate to minimize
the measurement error. The micro-TRI-gloss meter from BYK-Gardner
GmbH conforms with ISO 2813, ISO 7668, ASTM D 523, ASTM D 2457, DIN
67530, JIS Z8741. Transmittance, color, and haze were measured
using X-Rite 17 Color Spectrophotometer from X-Rite. Transmittance
(T) and haze are reported as a percent (%). Pencil hardness is
measured using protocols conforming with ASTM-D3363 standard, using
HA-3363 Garoco.RTM. Pencil Scratch Hardness Kit from Paul N.
Gardner Company, Inc., under a 500 g load.
[0127] Surface roughness (R.sub.a) may be determined by testing
coated substrates after cure using a Surftest SJ-210 Surface
Roughness Measuring Tester from Mitutoyo Corporation. Measurements
are usually taken in multiple locations on the substrate and an
average reported. Higher values indicate greater roughness. The
Surftest SJ-210 Surface Roughness Measuring Tester with a code of
178-561-01A uses a standard type drive unit with a 0.75 mN type
detector and a compact type display unit. It has a 2 .mu.m stylus
tip radius and a detect measuring force of 0.75 mN. The tester is
first calibrated with a precision roughness specimen with an
R.sub.a of 2.97 .mu.m. After calibration, the R.sub.a measurement
is done according ISO 4287-1997 with a traverse speed of 0.5 mm/s,
a cutoff related items .lamda.c of 0.8, and the number of sampling
lengths as 5. A total of 6 data are taken from the sample surface
in the area 5 mm from the edge. The average number is then recorded
as the surface roughness R.sub.a.
TABLE-US-00001 TABLE 1 Pencil Gloss Haze T % at hardness Samples
(GU) L* a* b* (%) 550 nm Ra (.mu.m) 500 g load Example 1 62.9 96.64
-0.01 -0.17 10.64 91.55 0.0993 7H 3 2 53.7 96.48 0 -0.14 12.1 91.14
0.1206 7H 3 61.4 96.43 0 -0.16 11.91 91.05 0.1050 7H 4 42.4 96.44
0.04 -0.32 18.01 91.04 0.1212 7H Example 1 61.2 96.53 0.02 -0.11
10.68 91.30 0.1040 9H 4 2 57.2 96.43 0.02 -0.10 11.42 91.01 0.1202
9H 3 58.3 98.57 0.07 -0.20 10.76 96.32 0.1172 9H 4 49.5 98.67 0.09
-0.28 13.88 96.57 0.1218 9H
[0128] 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 scope
of the invention as defined in the appended claims.
* * * * *