U.S. patent application number 13/314323 was filed with the patent office on 2012-07-05 for coating composition and uses thereof.
This patent application is currently assigned to ETERNAL CHEMICAL CO., LTD.. Invention is credited to Sheng-Wei LIN, Mao-Jung Yeh.
Application Number | 20120168666 13/314323 |
Document ID | / |
Family ID | 44489276 |
Filed Date | 2012-07-05 |
United States Patent
Application |
20120168666 |
Kind Code |
A1 |
LIN; Sheng-Wei ; et
al. |
July 5, 2012 |
COATING COMPOSITION AND USES THEREOF
Abstract
A coating composition comprising a photocatalyst composite and a
silicone resin is provided, in which the content of the
photocatalyst composite ranges from about 1% to about 70% by weight
(wt %), based on the total weight of the coating composition, and
the photocatalyst composite contains a heat insulation material and
a photocatalyst material. An energy-saving material is further
provided, which includes a substrate and a film formed from the
coating composition of the present invention on at least one of the
surfaces of the substrate. The energy-saving material is capable of
effectively shielding off infrared (IR) light, substantially
decreasing indoor temperature, and reducing power consumption. In
addition, in the presence of the photocatalyst which can absorb
ultraviolet light, the material also exhibits good superhydrophilic
and self-cleaning properties and provides antimicrobial and
deodorization effects.
Inventors: |
LIN; Sheng-Wei; (Kaohsiung,
TW) ; Yeh; Mao-Jung; (Kaohsiung, TW) |
Assignee: |
ETERNAL CHEMICAL CO., LTD.
|
Family ID: |
44489276 |
Appl. No.: |
13/314323 |
Filed: |
December 8, 2011 |
Current U.S.
Class: |
252/62 |
Current CPC
Class: |
B01J 37/0219 20130101;
B01J 37/0215 20130101; B01J 21/063 20130101; Y02A 30/00 20180101;
Y02A 30/261 20180101; B01J 23/14 20130101; Y02P 20/124 20151101;
C09D 5/32 20130101; C09D 7/61 20180101; C09D 5/1618 20130101; Y02P
20/10 20151101; Y02B 30/94 20130101; Y02B 30/90 20130101; C08L
83/00 20130101; B01J 35/004 20130101; B01J 23/06 20130101 |
Class at
Publication: |
252/62 |
International
Class: |
E04B 1/74 20060101
E04B001/74 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 31, 2010 |
TW |
099147427 |
Claims
1. A coating composition, comprising a photocatalyst composite and
a silicone resin, wherein the content of the photocatalyst
composite is about 1 to 70 wt %, based on the total weight of the
composition, and the photocatalyst composite comprises: (1) a heat
insulation material selected from the group consisting of antimony
tin oxide (ATO), indium tin oxide (ITO), aluminum zinc oxide (AZO),
indium zinc oxide (IZO), and gallium zinc oxide (GZO), and a
combination thereof; and (2) a photocatalyst material selected from
the group consisting of titanium dioxide, zinc oxide, strontium
titanate, and tin oxide, and a combination thereof, wherein the
content of the photocatalyst material is about 10 to 90 wt %, based
on the total weight of the photocatalyst composite.
2. The coating composition according to claim 1, wherein the
silicone resin is prepared through a sol-gel process.
3. The coating composition according to claim 1, further comprising
an organic solvent.
4. The coating composition according to claim 1, wherein the heat
insulation material is ATO or ITO.
5. The coating composition according to claim 1, wherein the
content of the photocatalyst material is about 40 to 85 wt %, based
on the total weight of the photocatalyst composite.
6. The coating composition according to claim 1, wherein the
photocatalyst material is titanium dioxide.
7. The coating composition according to claim 1, wherein the
photocatalyst composite has a particle size of about 2 to 100
nanometers (nm).
8. The coating composition according to claim 1, further comprising
inorganic particulates selected from the group consisting of silica
(SiO.sub.2), alumina (Al.sub.2O.sub.3), cadmium sulfide (CdS),
zirconia (ZrO.sub.2), calcium phosphate (Ca.sub.3(PO.sub.4).sub.2),
and calcium oxide (CaO), and a mixture thereof.
9. An energy-saving material, comprising: a substrate; and a film
formed from the coating composition according to claim 1 on at
least one surface of the substrate.
10. The energy-saving material according to claim 9, wherein the
film is formed by coating, spraying, or dipping the coating
composition according to claim 1 on at least one surface of the
substrate.
11. The energy-saving material according to claim 9, wherein the
film has a pencil hardness of H or higher as measured according to
JIS K5400 standard method.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a coating composition,
which can be coated on a substrate, so as to enable the surface of
the substrate to have self-cleaning and heat insulation effects.
The present invention further relates to an energy-saving material
containing a film formed from the coating composition of the
present invention.
[0003] 2. Description of the Prior Art
[0004] There are many materials for shielding the heat effect of
infrared light available in the market, for example, glass curtain
of a building, automobile glass, and heat insulation paper. In
short, the materials are provided for the purpose of allowing the
sunlight to pass through to provide light, while the heat source
(that is, heat effect of infrared light) is expected to be
insulated. However, with an existing glass having the infrared
light shielding property as an example, the production cost is too
high and the effect is less satisfactory. For example, it is known
that an ultra thin infrared light absorption silver film may be
embedded in the glass to shield the infrared light; however, the
preparation cost is high, and silver is easily oxidized, and thus
loses the infrared light shielding effect.
[0005] In addition, a material (for example, titanium dioxide of
high refractive index and silica of low refractive index) capable
of shielding the infrared light may be applied on glass or a lens
by vacuum evaporation, to form a film capable of shielding the
infrared light. However, the film thus formed has the following
disadvantages of high cost, complex manufacturing process, and
unsatisfactory effect, thus not meeting the requirement of economic
benefits.
[0006] In addition to the above two methods, an alternative
low-cost solution is proposed, in which a pigment or a dye is
admixed in the glass to absorb the infrared light in sunlight.
However, upon irradiation with intense sunlight or scattered light,
a fume like haze occurs to this kind of glass containing pigment or
dye, and thus the infrared light absorbing performance is
influenced, and the pigment or dye will be decomposed after long
time of use and lose the corresponding effects.
[0007] Furthermore, it is known that the photocatalyst has a
function of absorbing light (especially, UV light) to excite the
electrons, and thus has a photocatalytic performance. After
excitation with light, the photocatalyst material activates water
molecules or oxygen molecules in the air, to form hydroxyl radicals
or negative oxygen ions for oxidation reduction reaction, so as to
decompose pollutants in the environment. Thereby, the photocatalyst
material may be used to remove the pollutants in the air or waste
water, and inhibit bacteria attached to a surface, so as to achieve
an antimicrobial effect. Furthermore, upon irradiation with light,
free radicals or negative oxygen ions are formed and released from
the surface of the photocatalyst material due to the presence of
hydrogen molecules, and an empty position is formed at the position
originally occupied by oxygen. In this case, if any, the water
molecules in the environment will occupy the empty position and
lose a proton, to form a hydroxyl group, such that the
photocatalyst material exhibits a superhydrophilic property,
thereby achieving the self-cleaning and anti-fog effect.
[0008] Generally, as for a heat insulation film or window glass
coating having the infrared light shielding and UV light absorbing
functions, multi-layer processing is required to be performed on a
substrate, to form a composite film, the preparation process is
complex, and the preparation cost is high. Therefore, continuous
efforts are currently directed to provide a material having
infrared light shielding and UV light absorbing functions.
SUMMARY OF THE INVENTION
[0009] In order to achieve the above objectives, the present
invention provides a coating composition comprising a photocatalyst
composite and a silicone resin, in which the content of the
photocatalyst composite is about 1 to 70% by weight (wt %), based
on the total weight of the composition, and the photocatalyst
composite comprises:
[0010] (1) a heat insulation material, selected from the group
consisting of antimony tin oxide (ATO), indium tin oxide (ITO),
aluminum zinc oxide (AZO), indium zinc oxide (IZO), and gallium
zinc oxide (GZO), and a combination thereof; and
[0011] (2) a photocatalyst material, selected from the group
consisting of titanium dioxide, zinc oxide, strontium titanate, and
tin oxide, and a combination thereof, wherein the content of the
photocatalyst material is about 10 to 90 wt %, based on the total
weight of the photocatalyst composite.
[0012] The present invention further provides an energy-saving
material, which includes a substrate and a film applied on at least
one of the surfaces of the substrate, in which the film is formed
from the coating composition of the present invention, and has
self-cleaning and heat insulation effects.
[0013] The coating composition of the present invention can
effectively insulate or reflect the heat-causing infrared light,
such that the transmittance of the infrared light is greatly
reduced. The photocatalyst material exhibits an UV light absorbing
capability, a self-cleaning function, and anti-fog, antimicrobial,
and deodorization effects. Furthermore, the coating composition of
the present invention may be applied on a substrate through a
common coating method, and thus the preparation process is
relatively simple and cheap.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a comparison chart of light transmittance
according to Example 1.
[0015] FIG. 2 shows the decomposition rate of the coating
composition of the present invention for methylene blue, which
indicates the photocatalytic property of that the coating
composition.
[0016] FIG. 3 shows measurement values of a contact angle of the
coating composition of the present invention and water upon
irradiation with UV light.
DETAILED DESCRIPTION OF THE INVENTION
[0017] The term "about" used herein means a variation of .+-.10% of
an indicated value.
[0018] The coating composition of the present invention comprises a
photocatalyst composite and a silicone resin, in which the content
of the photocatalyst composite is about 1% to about 70 wt %, and
preferably about 40% to about 60 wt %, based on the total weight of
the composition. If the content of the photocatalyst composite is
lower than 1 wt %, the infrared light shielding and UV light
absorbing effects of the composition is insufficient; and if the
content is higher than about 70 wt %, the dispersivity of the
photocatalyst composite in the resin is sharply decreased, and the
coated composition is likely to fall off.
[0019] The photocatalyst composite comprises a heat insulation
material and a photocatalyst material, in which the content of the
photocatalyst material is about 10% to about 90 wt %, and
preferably about 40% to about 85 wt %, based on the total weight of
the photocatalyst composite.
[0020] The photocatalyst composite normally has a particle size of
from about 2 to about 100 nanometers (nm), preferably from about 5
to about 45 nm, and more preferably 10 to 35 nm. If the particle
size is smaller than 2 nm, the photocatalyst composite is not easy
to produce and is not practical, and if the particle size is
greater than 100 nm, the overall surface area becomes small, and
thus the transmittance of the visible light decreases, and the heat
insulation effect is poor. As the particle size of the
photocatalyst composite of the present invention is smaller than
the wavelength of visible light (from about 380 nm to about 780
nm), when the photocatalyst composite is irradiated with light, the
transmitted light will not be seriously scattered, thereby avoiding
the adverse influence on the quality of the transmitted light.
[0021] The heat insulation material in the photocatalyst composite
of the present invention is required to have an infrared
reflectivity of about 70% or higher, and can be selected from the
group consisting of antimony tin oxide (ATO), indium tin oxide
(ITO), aluminum zinc oxide (AZO), indium zinc oxide (IZO), and
gallium zinc oxide (GZO), and a combination thereof.
[0022] According to a preferred embodiment of the present
invention, when using ITO or ATO as the heat insulation material of
the photocatalyst composite, substantially a same heat insulation
effect can be achieved at a less material dose, as compared with
other materials, thus the photocatalyst composite is more cost
effective. Moreover, it is found that when the coating composition
includes ITO, it not only can effectively reflect infrared light
but exhibits a better visible light transmittance and can be
advantageously used as a transparent heat insulation material.
[0023] According to a preferred embodiment of the present
invention, preferred transparency can be achieved when ITO is used
as the heat insulation material of the photocatalyst composite. In
addition, it is found that when using ITO in the coating
composition of the present invention, the infrared light can be
effectively reflected, and substantially a same heat insulation
effect can be achieved at a less material dose, compared with other
materials, thus being more cost effective.
[0024] In addition to the heat insulation material capable of
shielding off or reflecting IR light, the photocatalyst composite
in the coating composition of the present invention further
comprises a photocatalyst material. The photocatalyst material has
a function of absorbing UV light to excite electrons, and thus has
photocatalytic property. Upon excitation with light, the
photocatalyst material activates water molecules or oxygen
molecules in the air to form hydroxyl free radicals or negative
oxygen ions for oxidation reduction reaction, so as to decompose
pollutants in the environment. Therefore, the photocatalyst
material may be used to remove the pollutants in the air or waste
water, and inhibit bacteria attached to a surface so as to achieve
an antimicrobial effect. Furthermore, the photocatalyst material
also exhibits a superhydrophilic property, and the moisture may
form into an aqueous film between the fouling and the photocatalyst
material, such that the adhesion of the fouling is reduced, and the
fouling on the aqueous film can be easily removed after being
washed with water or rainwater. Thus, the photocatalyst material
has a UV light absorbing capability and a self-cleaning function,
and provides anti-fog, antimicrobial, and deodorization
effects.
[0025] The photocatalyst material suitable for the photocatalyst
composite of the present invention can be any of those well known
to persons skilled in the art, and may be, for example, titanium
dioxide, zinc oxide, strontium titanate (SrTiO.sub.3), tin oxide,
or a mixture thereof, and is preferably titanium dioxide which is
relatively harmless to the environment or human body. In terms of
catalyst performance, titanium dioxide in an anatase crystal
structure is preferred. Furthermore, the particle size of the
photocatalyst material is required to be smaller than about 100 nm,
so as to exhibit a photocatalytic effect. For example, the particle
size of titanium dioxide is suitably about 1 to about 100 nm, and
preferably about 5 to about 30 nm; if the particle size is less
than 1 nm, titanium dioxide is difficult to be produced and not
easy to be dispersed, and if the particle size is greater than 100
nm, the photocatalytic effect will be greatly decreased.
[0026] The coating composition of the present invention comprises a
binder which can be, for example, but is not limited to an acrylic
resin, fluorocarbon resin or silicone resin. To prevent the
photocatalyst from being oxidized and being decomposed, the binder
is preferably a silicone resin. The silicone resin contained in the
coating composition of the present invention is present in an
amount of about 30 wt % to about 99 wt %, and preferably about 40
wt % to about 60 wt %, based on the total weight of the coating
composition.
[0027] The silicone resin useful for the present invention is not
particularly limited and can be that well known to persons skilled
in the art, that is, an organic polysiloxane resin with a main
chain consisting of repeating Si--O bonds where hydrogen atoms or
organic radicals are directly bonded to the silicon atoms, and of
the formula [R.sub.nSiO.sub.4-n/2].sub.m, wherein R represents
hydrogen or an organic radical, and independently is hydrogen,
C.sub.1-6 alkyl, C.sub.2-5 epoxy, or C.sub.6-14 aryl, and
preferably is hydrogen, methyl, ethyl,
##STR00001##
or phenyl; n is the number of the hydrogen atom(s) or organic
radical(s) bonded to the silicon atom and is in the range from 0 to
3; and m represents the degree of polymerization, and is an integer
of 2 or more. The steps for constructing the chemical structure of
polysiloxane include determining the length of the polymeric chain,
branching, and locating the places for attaching hydrogen(s) or
organic group(s). In view of the chemical structure, letters M
(denoting monofunctional group), D (difunctional group), T
(trifunctional group), and Q (tetrafunctional group) can be used to
represent the structural group(s) introduced into the polymeric
molecule.
[0028] Examples of Commercially available silicone resins include,
but are not limited to KBM-1003, KBE-402, KBE-403, KBM-502, KBM-04,
KBE-13, and KBE-103 manufactured by Shin Etsu Company; and Z-6018
and 3037 manufactured by Dow Corning Company.
[0029] The silicone resins can be used in single species and in
combination of two or more species. The silicone resin useful for
the present invention can be an oligomer of the formula
R.sup.1O--[SiR.sub.2O].sub.w--SiR.sub.2(OR.sup.1) in which w is an
integer of 1 to 1000, R is as defined hereinbefore and R.sup.1 is
independently H, C.sub.1-3 alkyl or C.sub.2-5 epoxy and preferably
is methyl, ethyl, or
##STR00002##
Such oligomer imparts the inventive coating composition with better
film-forming property, dispersivity, and ductility, and a high
surface hardness after being cured.
[0030] The suitable preparation method for the silicone resin used
in the present invention is not particularly limited. According to
the preferred embodiment of the present invention, the silicone
resin is formed through a sol-gel process. The sol-gel process
includes suspending a raw material of solid particles of about
several hundred nanometers in size (generally, an inorganic metal
salt), in a liquid. In a typical sol-gel process, the reactant will
undergo a series of hydrolysis and polymerization reactions, to
generate a colloidal suspension, in which the resulting substance
in the colloidal suspension condenses into a new phase of a solid
polymer containing solution, that is, gel. The properties of the
prepared sol-gel depends on the species of the raw material, the
species and concentration of the catalyst, the pH value, the
temperature, the amount of the solvent, and the species and
concentrations of the alcohol and the salt.
[0031] The coating composition of the present invention may
optionally comprise nano-size inorganic particulates, such that the
surface of the photocatalyst composite is covered with a layer of
the inorganic particulates, so as to avoid direct contact of the
photocatalyst with the substrate when the coating composition is
coated onto the surface of the substrate, and to avoid the
deterioration of the substrate that can be easily caused due to the
oxidation property of the photocatalyst. If present, the amount of
the inorganic particulates is about 0.1 wt % to about 40 wt %,
based on the total weight of the composite material. The inorganic
particulates useful for the present invention are not particularly
limited, and generally may be selected from silica (SiO.sub.2),
alumina (Al.sub.2O.sub.3), cadmium sulfide (CdS), zirconia
(ZrO.sub.2), calcium phosphate (Ca.sub.3(PO.sub.4).sub.2), calcium
oxide (CaO), and a combination thereof, with SiO.sub.2 being
preferred. According to a preferred embodiment of the present
invention, the photocatalyst composite is coated with a layer of
porous inorganic particulates. Specifically, the photocatalyst
composite in the composite material of the present invention is
coated with a layer of porous inorganic particulates, and thus will
not directly contact and destroy the substrate, and external
impurities (for example, odor molecules and bacteria) can penetrate
the porous inorganic particles through diffusion, arrive at and be
absorbed on the photocatalyst material, and are photocatalytically
decomposed, thereby achieving the cleaning, antimicrobial and
deodorization purposes.
[0032] An organic solvent may be further added to the coating
composition of the present invention, depending on the requirements
in application. When the organic solvent is used in the coating
composition of the present invention, the amount is about 1 wt % to
about 95 wt %, and preferably about 65 wt % to about 90 wt %, based
on the total weight of the coating composition. The organic solvent
may be any of those well known to persons skilled in the art, and
may be, for example, but is not limited to, an alkane, an aromatic
hydrocarbon, an ester, a ketone, an alcohol, or an ether alcohol.
The alkane solvent useful in the present invention may be selected
from the group consisting of n-hexane, n-heptane, iso-heptane, and
a mixture thereof. The aromatic hydrocarbon solvent useful in the
present invention may be selected from the group consisting of
benzene, toluene, and xylene, and a mixture thereof. The ketone
solvent useful in the present invention may be selected from the
group consisting of methyl ethyl ketone (MEK), acetone, methyl
iso-butyl ketone, cyclohexanone, and
4-hydroxy-4-methyl-2-pentanone, and a mixture thereof. The ester
solvent useful in the present invention may be selected from the
group consisting of iso-butyl acetate (IBAC), ethyl acetate (EAC),
butyl acetate (BAC), ethyl formate, methyl acetate, ethoxyethyl
acetate, ethoxypropyl acetate, ethyl iso-butyrate, propylene glycol
monomethyl ether acetate, and pentyl acetate, and a mixture
thereof. The alcohol solvent useful in the present invention may be
selected from the group consisting of ethanol, iso-propanol,
n-butanol, and iso-pentanol, and a mixture thereof. The ether
alcohol solvent useful in the present invention may be selected
from the group consisting of ethylene glycol monobutyl ether (BCS),
ethylene glycol monoethyl ether acetate (CAC), ethylene glycol
monoethyl ether (ECS), propylene glycol monomethyl ether, propylene
glycol monomethyl ether acetate (PMA), and propylene glycol
monomethyl propionate (PMP), and a mixture thereof.
[0033] The present invention further provides an energy-saving
material, which comprises a substrate and a film formed from the
coating composition as described above on at least one surface of
the substrate. The coating composition of the present invention can
be applied onto the at least one surface of the substrate by a
common application method, which is for example, coating, spraying,
or dipping, and then dried to form a smooth film. The existing
energy-saving materials generally have the disadvantages of low
coating hardness and being likely to be scratched, such that the
coating is very likely to be scratched after a long period of time,
and the scratched coating in turn seriously influences the
aesthetic appearance of an article, such as window. According to a
preferred embodiment of the present invention, the film of the
energy-saving material has a pencil hardness of H or higher and
preferably 3H or higher, as measured according to JIS K5400
standard method, and can effectively overcome the above-mentioned
disadvantages.
[0034] The above-mentioned substrate includes, but is not limited
to, glass, plastic, heat insulation plate for buildings, metal,
ceramic tile, wood, leather, stone, concrete, mural, fiber, cotton
fabric, appliances, lighting devices, and computer casings, with
glass and heat insulation plate for buildings being preferred.
[0035] According to a specific embodiment of the present invention,
the energy-saving material includes a glass and a film formed by
applying the foregoing coating composition by coating, spraying, or
dipping on at least one surface of the glass. The film has a
thickness of about 0.5 to about 50 micrometers. The energy-saving
material according to the present invention has a transmittance of
the visible light under wavelength of 550 nm of about 70% or more,
preferably of about 90% or more. The energy-saving material of the
present invention has a good visual effect and an infrared light
(thermal radiation) reflectance of about 70% or higher, and
exhibits a good heat insulation effect, so it can substantially
decrease the indoor temperature and reduce power consumption, has a
better energy-saving effect and a higher transmittance of visible
light, compared with a glass attached with a traditional heat
insulation film available in the market, and thus having the
advantages of greatly reduced cost, simple application, and wide
application in glass curtain for buildings or automobile glass.
Furthermore, almost all the heat insulation materials (such as
lanthanum hexaboride) contained in the coating compositions for
energy-saving materials available in the market absorb, rather than
reflect, the infrared light in sunlight, and the absorbed infrared
light is converted into heat energy, and stored in glass, such that
the surface temperature of the glass rises, and thus the risk of
glass cracking exists.
[0036] Moreover, the photocatalyst composite in the coating
composition of the present invention has superhydrophilic property,
such that the moisture in the air is attracted to form a super thin
aqueous film between the fouling and the photocatalyst composite
and to reduce the adhesion of the fouling. In addition, the
photocatalyst can also oxidize organic fouling particles and break
down the structure thereof, such that the particles will not be
attached on the surface of the glass. Upon rainfall, due to the
effect of superhydrophilic property, the rain water evenly
penetrates to an interface between the fouling and the
photocatalyst, and the fouling on the aqueous film can be easily
washed off when the rain water is accumulated to a sufficient
extent, such that the frequency of maintaining the surface of a
common glass clean with the aid of human power is lowered, and the
self-cleaning effect is achieved.
[0037] In the past, for obtaining energy-saving materials,
treatments for shielding infrared light and absorbing UV light
needed to be performed on the substrate, so effects both on
shielding infrared light and absorbing UV light can be achieved
only after a multi-layer processing was conducted on the substrate.
However, by using the coating composition of the present invention,
an energy-saving material having the effects on shielding infrared
light and absorbing UV light can be obtained only through one time
application treatment on the surface of the substrate. As the film
applied on the substrate contains photocatalyst material, it can
absorb UV light, thus providing self-cleaning, anti-fog,
antimicrobial, and deodorization efficacies; and due to the
presence of the heat insulation material, the film can also
effectively reflect infrared light so as to reduce the
transmittance of the infrared light while allowing the visible
light to pass through. In addition, since the size of the particles
contained in the film is less than the wavelengths of the visible
light, the particles will not scatter the transmitted light and
will not influence the quality of the transmitted light, and the
transparency of the substrate can be maintained.
[0038] The present invention further provides a method for
preparing a coating composition, which includes obtaining an
intermediate product of titanium sulfate through hydrolysis of
titanium tetrachloride, then adding a heat insulation material, to
obtain a photocatalyst composite powder at a low temperature, and
then mixing and grinding the resulting photocatalyst composite
powder and a silicone resin, to obtain the coating composition of
the present invention.
[0039] According to a preferred specific embodiment of the present
invention, a sol-gel silicone resin and a photocatalyst composite
powder in suitable proportions are mixed and optionally a solvent
is added, followed by grinding, so as to obtain the coating
composition of the present invention. The above-mentioned
photocatalyst composite powder can be obtained by the process
comprising the following steps:
[0040] (a) obtaining a white gel hydrate through hydrolysis of
titanium tetrachloride;
[0041] (b) adding concentrated sulfuric acid into the resulting
hydrate in a reactor, and stirring for 10-50 min, to obtain a
titanium sulfate solution;
[0042] (c) sufficiently mixing the titanium sulfate solution, and
stirring for 0.5-5 hrs at normal temperature;
[0043] (d) heating to 80-100.degree. C., and reacting for 2-7 hrs
at a constant temperature; and
[0044] (e) adding an ITO powder at a suitable ratio, stirring for
1-4 hrs for mixing, dripping 4-6 M aqueous sodium hydroxide
solution, filtering, washing, and drying at room temperature, to
obtain the photocatalyst composite powder (TiO.sub.2+ITO).
[0045] The present invention will be further described in detail
through the following examples. It should be understood that the
examples are merely used to exemplify the present invention, but
not intended to limit the scope of the present invention. Any
modification or alteration obvious to persons skilled in the art
and made without departing from the spirit and principle of the
present invention should fall within the scope of the present
invention.
EXAMPLES
[0046] In the examples and comparative examples below, the
percentages are weight percents (wt %), unless otherwise
stated.
Example 1
[0047] 200 ml of a 3.9 M titanium tetrachloride solution was
diluted with water to a total volume of 2000 ml, and then 500 ml (5
M) of aqueous ammonia was dripped, to generate a white titanium
hydroxide precipitate, which was filtered, washed with deionizer
water (200 ml.times.3) to remove the remaining water, to obtain
titanium hydroxide [Ti(OH).sub.4] as a white gel.
[0048] 100-150 g of concentrated sulfuric acid (18M) was added to
250 g of the above-mentioned titanium hydroxide, and stirred for 30
min, to obtain a transparent and clear titanium sulfate solution.
The titanium sulfate solution was placed in a reactor, 32.2 g of an
aqueous SiO.sub.2 solution (20%) was added, stirred for 4 hrs at
normal temperature, then heated to 100.degree. C., and reacted for
2 hrs. 100 g of an aqueous ITO solution (10%) was added, the
reaction was stirred at normal temperature for 2 hrs, to obtain a
mixture.
[0049] 600 ml (5 M) of an aqueous sodium hydroxide solution was
dripped, then the resulting solution was adjusted to a neutral pH,
and a resulting precipitate was filtered, washed, and dried at room
temperature, to obtain a grey blue powder, which was detected
through XRD to be a photocatalyst composite of an anatase type
photocatalyst and ITO.
[0050] The resulting photocatalyst composite was added to a
silicone resin (having a solid content of 27%) at a ratio (in
weight) of the photocatalyst composite:resin=1:3, stirred, ground,
dispersed, and applied onto a glass plate to form a coating having
a thickness of 5 micrometers. A light transmittance measurement,
organic (methylene blue) decomposition test, hydrophilic property
test, and heat insulation test were conducted.
[0051] A blank glass plate and a coating were placed in a
UV/visible/near infrared spectrometer (manufactured by JASCO
Incorporation, Model V-570) respectively, to measure the light
transmittance in the range of UV light to near infrared light. The
test results are as shown in FIG. 1 (in which the range between the
two vertical lines represent visible light). The zigzag line
represents the transmittance values of an uncoated glass plate (the
transmittance is about 100%), the solid line represents the
transmittance values of a glass plate with a single coating on one
surface, and the dot line represents the transmittance values of
glass plate with coatings on both surfaces. It can be seen from the
test results that, the coating of the present invention can greatly
reduce the transmittance of UV light and near infrared light, and
effectively shield UV light and near infrared light.
[0052] (35.+-.0.3) ml of methylene blue was added to a cylindrical
test column having an inner diameter of 40 mm and a height of 30
mm, and then square glass with a side length of (6012) mm and
having a coating was placed thereon. The coating was irradiated
with UV light of (1.00.+-.0.05) mW/cm.sup.2 for 6 hrs in total, and
the decomposition rate of methylene blue was measured every 1 hr.
The test results are as shown in FIG. 2. It can be seen from the
test results that, upon irradiation with UV light, the coating of
the present invention can effectively decompose organics (methylene
blue), and thus has photocatalytic property.
[0053] Taking a square glass having a side length of (100.+-.2) mm
with a coating as a test plate, 1 .mu.L of water contacted with the
test plate, an image is captured, and the contact angle was
measured with a contact angle tester. The coating was irradiated
with UV light of (1.0.+-.0.1) mW/cm.sup.2, and the contact angle
was measured once every 50 hrs. The test results are as shown in
FIG. 3. It can be seen from the test results that, the coating of
the present invention has superhydrophilic property upon
irradiation with UV light.
[0054] A coating was placed at a position of about 20 cm below an
infrared light bulb (PHILIPS Corporation), and a beaker containing
100 g of water was placed at a position of about 15 cm below the
glass coating, and irradiated with the infrared light bulb, and the
surface temperature was regularly measured with an infrared
thermometer (TES series, TES Electrical Electronic Corp.) every 5
min. The test results are as shown in Table 1 below, and the
surface temperature of the coating after 30-minutes of irradiation
is as shown in Table 2 below.
Example 2
[0055] 200 ml of a 3.9 M titanium tetrachloride solution was
diluted with water to a total volume of 2000 ml, and then 500 ml (5
M) of aqueous ammonia was dripped, to generate a white titanium
hydroxide precipitate, which was filtered, washed with deionized
water (200 ml.times.3) to remove the remaining water, to obtain
titanium hydroxide [Ti(OH).sub.4] as a white gel.
[0056] 100-150 g of concentrated sulfuric acid (18M) was added to
250 g of the above-mentioned titanium hydroxide, and stirred for 30
min, to obtain a transparent and clear titanium sulfate solution.
The titanium sulfate solution was placed in a reactor, 32.2 g of an
aqueous SiO.sub.2 solution (20%) was added, stirred for 4 hrs at
normal temperature, then heated to 100.degree. C., and reacted for
2 hrs. 100 g of an aqueous ATO solution (15%) was added, the
reaction was stirred at normal temperature for 2 hrs, to obtain a
mixture.
[0057] 600 ml (5 M) of an aqueous sodium hydroxide solution was
dripped, then the resulting solution was adjusted to a neutral pH,
and a resulting precipitate was filtered, washed, and dried at room
temperature, to obtain a deep blue powder, which was detected
through XRD to be a photocatalyst composite of an anatase type
photocatalyst and ATO.
[0058] The resulting photocatalyst composite was added to a
silicone resin (having a solid content of 27%) at a ratio (in
weight) of the photocatalyst composite:resin=1:3, stirred, ground,
dispersed, and applied onto a glass plate to form a coating having
a thickness of 5 micrometers. A heat insulation test was
conducted.
[0059] A coating was placed at a position of about 20 cm below an
infrared light bulb (PHILIPS Corporation), and a beaker containing
100 g of water was placed at a position of about 15 cm below the
glass coating, and irradiated with the infrared light bulb, and the
surface temperature was regularly measured with an infrared
thermometer (TES series, TES Electrical Electronic Corp.) every 5
min. The test results are as shown in Table 1 below, and the
surface temperature of the coating after 30-minutes of irradiation
is as shown in Table 2 below.
Comparative Example 1
[0060] 200 ml of a 3.9 M titanium tetrachloride solution was
diluted with water to a total volume of 2000 ml, and then 500 ml (5
M) of aqueous ammonia was dripped, to generate a white titanium
hydroxide precipitate, which was filtered, washed with deionized
water (200 ml.times.3) to remove the remaining water, to obtain
titanium hydroxide [Ti(OH).sub.4] as a white gel.
[0061] 100-150 g of concentrated sulfuric acid (18M) was added to
250 g of the above-mentioned titanium hydroxide, and stirred for 30
min, to obtain a transparent and clear titanium sulfate solution.
The titanium sulfate solution was placed in a reactor, 32.2 g of an
aqueous SiO.sub.2 solution (20%) was added, stirred for 4 hrs at
normal temperature, then heated to 100.degree. C., and reacted for
2 hrs. 100 g of an aqueous lanthanum hexaboride solution (10%) was
added, the reaction was stirred at normal temperature for 1 hr, to
obtain a mixture.
[0062] 600 ml (5 M) of an aqueous sodium hydroxide solution was
dripped, and a resulting precipitate was filtered, washed, and
dried at room temperature, to obtain a gray blue powder, which was
detected through XRD to be a photocatalyst composite of an anatase
type photocatalyst and lanthanum hexaboride.
[0063] The resulting photocatalyst composite was added to a
silicone resin (having a solid content of 27%) at a ratio (in
weight) of the photocatalyst composite:resin=1:3, stirred,
dispersed, and applied onto a glass plate to form a coating having
a thickness of 5 micrometers. A heat insulation test (utilizing an
infrared light bulb, PHILIPS Corporation) was conducted.
[0064] A coating was placed at a position of about 20 cm below an
infrared light bulb, and a beaker containing 100 g of water was
placed at a position of about 15 cm below the glass coating, and
irradiated with the infrared light bulb, and the surface
temperature was regularly measured with an infrared thermometer
(TES series, TES Electrical Electronic Corp.) every 5 min. The test
results are as shown in Table 1 below, and the surface temperature
of the coating after 30-minutes of irradiation is as shown in Table
2 below.
Comparative Example 2
[0065] A commercially available heat insulation paper (manufactured
by Top Color Film Co. Ltd., trade name; SD series Top Colour) was
attached to a glass surface, and placed at a position of about 20
cm below an infrared light bulb, and a beaker containing 100 g of
water was placed at a position of about 15 cm below the glass
attachment and irradiated with the infrared light bulb, and the
surface temperature was regularly measured with an infrared
thermometer (TES series, TES Electrical Electronic Corp.) every 5
min. The test results are as shown in Table 1 below, and the
surface temperature of the attachment after 30 minutes of
irradiation is as shown in Table 2 below.
TABLE-US-00001 TABLE 1 Temperature test Temperature (.degree. C.)
Comparative Comparative Time (min) Glass Example 1 Example 2
Example 1 Example 2 0 24 24 24 24 24 5 34 34 33.8 34 34.8 10 39.8
35.3 34.7 38.3 39.3 15 42.6 39.8 38.5 40.1 40.9 20 45 42.3 39.8
43.1 44.1 25 46.1 43.6 42 45.8 44.8 30 48.6 43.6 43 46.5 45.1
TABLE-US-00002 TABLE 2 Surface temperature of the glass after 30
minutes of irradiation Temperature (.degree. C.) Comparative
Comparative Time (min) Glass Example 1 Example 2 Example 1 Example
2 30 70.8 60 61.4 86 68.4
[0066] It can be seen from the comparison of the results in Table 1
that, application of the coating having the coating composition of
the present invention on the surface of the glass can effectively
insulate heat.
[0067] It can be seen from the comparison between Examples 1 and 2
and Comparative Example 1 that the coating composition of the
present invention can effectively reflect infrared light, resulting
in a lower surface temperature on glass, thereby avoiding the risk
of glass cracking.
[0068] It can be seen from the comparison between Examples and 2
and Comparative Example 2 that the coating composition of the
present invention, comparing to heat insulation paper, provides a
lower surface temperature on glass coating. The coating composition
can be applied more easily than heat insulation paper, and is less
likely to accumulate heat energy or generate heat convection,
thereby providing a better heat insulation effect.
* * * * *