U.S. patent application number 14/388697 was filed with the patent office on 2015-06-11 for nanometric tin-containing metal oxide particle and dispersion, and preparation method and application thereof.
The applicant listed for this patent is NANOMATERIALS TECHNOLOGY PTE LTD, XIAMEN NANOTECH CO LTD. Invention is credited to Jianfeng Chen, Zhigang Shen, Hock Sing Sher, Wei Kian Soh, Aici Wang, Sung Lai Jimmy Yun, Jiyao Zhang, Jie Zhong.
Application Number | 20150160379 14/388697 |
Document ID | / |
Family ID | 49258222 |
Filed Date | 2015-06-11 |
United States Patent
Application |
20150160379 |
Kind Code |
A1 |
Shen; Zhigang ; et
al. |
June 11, 2015 |
NANOMETRIC TIN-CONTAINING METAL OXIDE PARTICLE AND DISPERSION, AND
PREPARATION METHOD AND APPLICATION THEREOF
Abstract
There is disclosed a tin-containing metal oxide nanoparticle,
which has an index of dispersion degree less than 7 and a narrow
particle size distribution which is defined as steepness ratio less
than 3. There is disclosed dispersion, paint, shielding film and
their glass products which comprise the said nanoparticles.
Besides, there are also disclosed processes of making the
tin-containing metal oxide nanoparticle and their dispersion. The
tin-containing metal oxide nanoparticles and their dispersion
disclosed herein may be applied on the window glass of houses,
buildings, vehicles, ships, etc. There is provided an excellent
function of infrared blocking with highly transparent, and to
achieve sunlight controlling and thermal radiation controlling.
Inventors: |
Shen; Zhigang; (Singapore,
SG) ; Soh; Wei Kian; (Singapore, SG) ; Zhang;
Jiyao; (Singapore, SG) ; Wang; Aici;
(Singapore, SG) ; Zhong; Jie; (Singapore, SG)
; Yun; Sung Lai Jimmy; (Singapore, SG) ; Sher;
Hock Sing; (Singapore, SG) ; Chen; Jianfeng;
(Singapore, SG) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
XIAMEN NANOTECH CO LTD
NANOMATERIALS TECHNOLOGY PTE LTD |
Fujian
Singapore |
|
CN
SG |
|
|
Family ID: |
49258222 |
Appl. No.: |
14/388697 |
Filed: |
March 27, 2013 |
PCT Filed: |
March 27, 2013 |
PCT NO: |
PCT/CN2013/073240 |
371 Date: |
September 26, 2014 |
Current U.S.
Class: |
252/587 ;
423/594.7; 423/594.9; 428/402 |
Current CPC
Class: |
C01P 2006/60 20130101;
C01P 2004/64 20130101; C03C 2217/476 20130101; C03C 17/007
20130101; Y10T 428/2982 20150115; C03C 2217/74 20130101; C03C
2217/445 20130101; C03C 2217/485 20130101; G02B 5/208 20130101;
C08K 13/02 20130101; C01P 2002/84 20130101; C03C 17/009 20130101;
C01P 2002/72 20130101; G02B 5/206 20130101; C03C 2217/475 20130101;
C01P 2004/04 20130101; C01P 2002/50 20130101; C01G 30/026 20130101;
B82Y 30/00 20130101; C01P 2004/52 20130101; G02B 1/14 20150115;
C01P 2004/54 20130101; C01G 19/00 20130101; C01G 30/00
20130101 |
International
Class: |
G02B 1/14 20060101
G02B001/14; C01G 30/02 20060101 C01G030/02; C01G 19/00 20060101
C01G019/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 28, 2012 |
CN |
201210086571.2 |
Claims
1-39. (canceled)
40. Tin-containing metal oxide nano-particles, said tin-containing
metal oxide including tin element and a metallic element other than
tin, wherein the tin-containing metal oxide nano-particles have a
particle diameter distribution as defined with an index of
dispersion degree of less than 7 and a steepness ratio of less than
3.
41. The tin-containing metal oxide nano-particles according to
claim 40, wherein said tin-containing metal oxide nano-particles
are coated on surface with a surfactant, said surfactant is
selected from a non-silane surface modifying agent, a silane
coupling agent, a titanate coupling agent, or a mixture thereof,
preferably the non-silane surface modifying agent is selected from
sodium dodecyl sulphate, sodium lauryl sulphate, sodium laurate,
sodium oleate, sodium naphthenate, sodium stearate, sodium
abietate, sodium iso-octoate, sodium linoleate, sodium caproate,
sodium ricinate, ethyl acetate, sodium acetate, dioctylsodium
sulphosuccinate, polyoxyethylene sorbitan monooleate, sorbitan
monooleate, sorbitan trioleate, PLURONIC.RTM., polysorbate,
N-polyvinyl pyrrolidone, polyethylene glycol, polyoxyethylene,
bis-2 hydroxyethyl oleyl amine, hexadecyltrimethyl ammonium
bromide, hydroxypropyl cellulose, hydroxypropylmethyl cellulose,
maltose sugar, sucrose, citric acid, (ethylene)glycol, acrylic
acid, methacrylic acid, .beta.-hydroxyethyl acrylate, tetraethyl
orthosilicate or a mixture thereof, the silane coupling agent is
preferably selected from alkyl-trialkoxy-silane,
(methyl)acryloxy-alkoxy-trialkoxy silane,
acryloyloxy-alkoxy-trialkoxy silane,
(methyl)acryloyloxy-alkyl-alkyl-dialkoxy silane,
acryloyloxy-alkyl-alkyl-dialkoxy silane,
(methyl)acryloyloxy-alkyl-dialkyl-alkoxy silane,
acryloyloxy-alkyl-dialkyl-alkoxy silane, thiol-alkoxy-trialkoxy
silane, .gamma.-methacryloxypropyltrimethoxy silane, aryl-trialkoxy
silane, vinyl silane, 3-glycidyloxypropyl-trialkoxy silane,
polyether silane, .gamma.-aminopropyl-triethoxy silane,
.gamma.-glycidyloxypropyltrimethoxy silane,
.gamma.-(methacryloyloxy) propyl-trimethoxy silane,
.gamma.-mercaptopropyltrimethoxy silane,
.gamma.-aminoethyl-aminopropyl-trimethoxy silane,
bis-propyl-triethoxy silane,
N-(.beta.-aminoethyl)-.gamma.-(aminopropyl)-methyldimethoxy silane,
N-(.beta.-aminoethyl)-.gamma.-(aminopropyl)-trimethoxy silane,
.gamma.-aminoethyl-aminopropyl-trimethoxy silane,
hexadecyltrimethoxy silane, or a mixture thereof.
42. The tin-containing metal oxide nano-particles according to
claim 40, wherein said metallic element other than tin is selected
from antimony, indium, titanium, copper, zinc, zirconium, cerium,
yttrium, lanthanum, niobium or a mixture thereof, preferably
antimony, indium or a mixture thereof; and the molar ratio of said
metallic element other than tin to tin is 1:0.01 to 1:100, or
1:0.05 to 1:50, or 1:0.05 to 1:20, or 1:0.05, or 1:0.1, or 1:0.15,
or 1:0.2, or 1:5, or 1:10, or 1:15, or 1:20.
43. The tin-containing metal oxide nano-particles according to
claim 40, wherein said tin-containing metal oxide is an
antimony-tin oxide or an indium-tin oxide.
44. The tin-containing metal oxide nano-particles according to
claim 40, wherein said tin-containing metal oxide nano-particles
have a crystal structure, or a tetragonal cassiterite, bixbyite,
tetragonal cassiterite-like or bixbyite-like structure.
45. The tin-containing metal oxide nano-particles according to
claim 40, wherein the index of dispersion degree is less than 5, or
less than 4, or less than 3, or less than 2; and the steepness
ratio is less than 2, or less than 1.8, or less than 1.5, or less
than 1.3.
46. The tin-containing metal oxide nano-particles according to
claim 40, wherein said tin-containing metal oxide nano-particles
have an initial average particle diameter of 2-50 nm, or 2-20 nm,
or 2-10 nm.
47. A method for preparing the tin-containing metal oxide
nano-particles according to claim 40, the method comprises steps
of: (1) reacting a solution containing tin ions and a solution
containing ions of other metal with a precipitant solution to form
tin-containing metal oxide precursor particles and a first
by-product in ionic form; (2) separating the tin-containing metal
oxide precursor particles from the first by-product in ionic form
to obtain tin-containing metal oxide precursor particles
substantially free of ionic impurities; (3) reacting the
tin-containing metal oxide precursor particles substantially free
of ionic impurities with an oxidizing agent or a reducing agent to
obtain tin-containing metal oxide particles and a second by-product
in ionic form; (4) separating the tin-containing metal oxide
particles from the second by-product in ionic form to obtain
tin-containing metal oxide nano-particles substantially free of
ionic impurities.
48. The method according to claim 47, wherein in one or more of
steps (2), (3) and (4), the tin-containing metal oxide precursor
particles or the tin-containing metal oxide particles are coated
with a surfactant, preferably a surfactant in an amount of 0.01% to
30% relative to the weight of tin-containing metal oxide precursor
particles or tin-containing metal oxide particles is added in one
or more of step (2), (3) and (4).
49. The method according to claim 47, wherein the separating of
step (2) or (4) is carried out by any one of methods of
liquid-liquid phase transfer, liquid-liquid phase transfer after
washing, centrifugation after washing, filtration after
washing.
50. The method according to claim 47, wherein the reacting of step
(1) is carried out at a temperature of less than 100.degree. C., or
at a temperature range of 40-80.degree. C., under non-acidic
condition, or substantially alkaline condition, in an aqueous
medium, the aqueous medium preferably comprising at least one of
water, alcohols, amides, ketones, epoxides and mixtures thereof,
and more preferably comprising one or more alcohols mixed with
water, wherein the alcohols have a volume of 1% to 99% relative to
water.
51. The method according to claim 47, wherein the tin ions and/or
ions of other metal in step (1) are derived from their acetate,
halide, nitrate, phosphate, sulfate, perchlorate, borate, iodate,
carbonate, perchlorate, tartrate, formate, gluconate, lactate,
sulfamate, hydrates or mixtures of these salts.
52. The method according to claim 47, wherein said precipitating
agent in step (1) is a base, the base preferably being an
oxygen-containing base, the oxygen-containing base preferably being
selected from alkali metal hydroxides, alkaline earth metal
hydroxides, alkali metal carbonates, alkaline earth metal
carbonates, alkali metal bicarbonates, ammonia, organic bases and
mixtures thereof.
53. The method according to claim 47, wherein step (3) is carried
out at a temperature of greater than 100.degree. C. and 1 to 20
atmospheres, preferably at a temperature of 150-400.degree. C. and
5 to 10 atmospheres.
54. The method according to claim 47, wherein said oxidizing agent
in step (3) is a peroxide, preferably selected from
Na.sub.2O.sub.2, K.sub.2O.sub.2, H.sub.2O.sub.2 and peroxyacetic
acid, and the reducing agent in step (3) is selected from hydrazine
hydrate, ethylenediamine, oxalic acid, formaldehyde, acetaldehyde,
metallic tin powder, sodium borohydride and a mixture thereof.
55. The method according to claim 47, wherein said step (1) and/or
step (3) is carried out under high shear condition.
56. A dispersion of tin-containing metal oxide nano-particles,
comprising a dispersion medium and the tin-containing metal oxide
particles according to claim 40.
57. The dispersion of tin-containing metal oxide nano-particles
according to claim 56, wherein the tin-containing metal oxide
nano-particles have a solid content of at least 5%, preferably at
least 10%, or at least 25%, or at least 30%, or at least 40%, or at
least 50%, relative to the weight of the dispersion, and the
dispersion medium is selected from water, ethyl acetate, butyl
acetate, alcohols, alkenes, ethers, ketones, aromatic solvents and
mixtures thereof.
58. The dispersion of tin-containing metal oxide nano-particles
according to claim 56, further comprising metal oxide
nano-particles for blocking UV light.
59. The dispersion of tin-containing metal oxide nano-particles
according to claim 58, wherein the metal oxide nano-particles for
blocking UV light are selected from at least one of zinc oxide,
titanium oxide and cerium oxide, and said metal oxide
nano-particles for blocking UV light is in an amount of at least 5%
relative to the weight of the dispersion.
60. A sunlight control composite material, comprising the
tin-containing metal oxide nano-particles according to claim
40.
61. A material permeable to visible light, comprising the
tin-containing metal oxide nano-particles according to claim 40.
Description
TECHNICAL FIELD
[0001] The present invention relates to a high transparency, low
radiation, energy-saving composite material for glass, and more
particularly, to tin-containing metal oxide nano-particles and
their dispersion, the preparation methods of the nano-particles and
dispersion, sunlight-control composition material comprising the
tin-containing metal oxide particles or their dispersion, and the
high transparency, low radiation and energy-efficient glass.
BACKGROUND
[0002] With the rapid development of science and technology and
industrial production, energy resource and the environment
increasingly attract whole social attention with higher demands for
energy saving and environmental protection. Regarding to energy
consumption, energy consumption from buildings accounts for nearly
40% of the total social energy consumption, of which the energy
loss through the glass doors and windows in the building energy
consumption reaches more than 50%, that is, the glass doors and
windows has become the largest energy vulnerability of buildings.
The main energy consumption within the building is due to heating
and air conditioning. Improving windows heat insulation performance
is an effective way to reduce building energy consumption. Energy
saving performance of architectural glass, has become the key to
achieve energy saving in buildings. To achieve energy-saving in
architectural glass, the sunlight through the glass has to be
controlled.
[0003] More than 99% of solar radiation spectrum is at the
wavelength range of 0.15 to 4.0 .mu.m. About 50% of solar radiation
energy is in the visible region of the spectrum (wavelength of 0.4
to 0.76 .mu.m), 3% in the ultraviolet (UV) spectral region
(wavelength of <0.38 .mu.m), 47% in the infrared (IR) region of
the spectrum (wavelength of >0.76 .mu.m), which near-IR ray is
known as hotline. However, maximum transmittance of ordinary glass
happens to be in the region of the solar radiation spectrum,
meaning that its sunlight transmission is not influenced. It is
necessary to achieve heat insulation and energy-saving in the
constructions, automotive and ships through the glass coated
sunlight control coating or film, thus saving energy for heating
and air conditioning. Sunlight control refers to regulation of
different wavelengths and heat energy of sunlight through glass
products accessing to certain spaces (buildings, cars or ships
internal). Apparently, under the premise without affecting space
lighting, blocking and absorbing of UV and IR and reducing thermal
radiation rate are effective ways to control sunlight. UV does not
account for a large proportion in energy, but greatly harmful to
the surface paint of furniture and human bodies, which is one of
the reasons that anti-UV glass has been increasingly widely used.
On the one hand, by reducing solar energy through sunlight control
can obtain reduction of heat flux of accessing to certain space
(building, car or ship), so that the space inside will keep cool,
thus to reduce the need for air conditioning, finally to achieve
purposes of energy saving and environmental protection. On the
other hand, by reducing the heat radiation, the glass can become
medium and far IR reflector, to reduce the heat flux through the
glass outwardly, thereby reducing air conditioning requirements and
the cost, to achieve the purpose of energy saving. improving window
insulation performance by effective low thermal radiation coating
can improve interior comfort in summer and winter.
[0004] For sunlight control and low thermal radiation properties
and commercially acceptable coated glass article, the manufacturing
considerations are cost, life and capabilities of maintaining the
relative performances (solar transmittance, visibility, colour,
transparency, and the shielding factor). Currently, methods for the
preparation of coated glass for sunlight control and low thermal
radiation are mostly magnetron sputtering, PVD, CVD coating and the
thermal spray coating. Specifically, the additives which are
against or absorb UV and IR, through the above methods, sputter or
coat onto the glass to achieve effective control of sunlight into
the room. Equipment prices by using above methods are expensive
with restrictions on the substrate and the substrate shape, size.
Furthermore, the methods are difficult to apply to existing
glasses, therefore meeting a very limited commercial promotion. At
present, coated glasses are mainly used in automotive, which market
is basically monopolized by very expensive films from companies of
the United States 3M, V-BEST, JOINNS, JOHNSON, and difficult to be
extended to architectural glass.
[0005] Without aging concern, inorganic nano-additives can be used
permanently, while organic additives usually aging with a life
period. Therefore, commercial applications with inorganic additives
is growing. Commercial inorganic additives with UV-blocking
property are metal oxides, such as zinc oxide, titanium oxide and
cerium. IR-blocking metal oxides are antimony tin oxide (ATO) and
indium tin oxide (ITO). Another commercial inorganic additive
absorbing IR is lanthanum hexaboride. In recent years, the rise of
the glass insulation coating or film, are increasingly focused on
the use of the metal oxide as an additive.
[0006] Ideally, the particles in the glass coating or film matrix
must be less than the nominal particle diameter of 100 nm, in order
to maintain the transparency and pellucidity of the original glass.
This is one of the main reasons that nanotechnology draw attentions
in this area. In addition, the metal oxide nano-particles in the
coating or film will not form a conductive film, therefore do not
interfere with operation of the radiation transmitting and
receiving devices within the protective structure glazing.
[0007] In the preparation of functional metal oxide dispersion, it
is necessary to mix at least two sorts of metal oxide
nano-particles with blocking UV or IR property in dispersions. The
traditional method is to disperse metal oxide particles in certain
solvent with some dispersant by ball milling or sanding milling.
This simple powder reprocessing approach may cause serious
aggregation, especially due to the high surface energy of
nano-particles. Moreover, the uneven intensity of ball milling or
sanding milling may lead to non-uniform secondary particle size of
the dispersed particles; in addition, ball milling and sanding
milling inevitably introduce impurities. Dispersion and the
modification belonging to physical modification methods, affecting
the stability of functional dispersion, which is difficult to
maintain the particles in the dispersion in nanoscale and keep
stable for long time. These will affect the application of the
functional dispersion, ultimately affect the transparency and other
properties of the glass coating or film.
[0008] Therefore, there is a need to develop tin-containing metal
oxide nano-particles and their dispersions which are economically
viable, high transparent and blocking UV and IR, able to use in the
glass coating and film with good dispersion stability, overcome or
ameliorate the above mentioned disadvantages.
[0009] Therefore, there is a need to invent a preparation method of
tin-containing metal oxide nano-particles and their dispersions
which are economically viable, high transparent and blocking UV and
IR, able to use in the glass coating and film with dispersion
stability, and overcome or ameliorate the above mentioned
disadvantages.
SUMMARY OF THE INVENTION
[0010] The object of the present invention is to provide one kind
of mono-dispersed, stable tin-containing metal oxide
nano-particles, dispersions and glass composite materials, which
have high transparency and IR blocking function. A further object
of the present invention is to provide a low-cost mass production
method of the above-mentioned tin-containing metal oxide
nano-particles and the dispersion. Another object of the present
invention is to provide the sunlight control composite material and
glass products comprising the above-mentioned tin-containing metal
oxide nano-particles or dispersion with high transparency and IR
blocking (or simultaneously blocking UV and IR) function.
[0011] According to a first aspect, the present invention provides
tin-containing metal oxide nano-particles, said tin-containing
metal oxide including tin element and another metallic element
except tin, wherein the tin-containing metal oxide nano-particles
having the index of dispersion degree of less than 7, and size
distribution in steepness ratio of less than 3.
[0012] In present invention, the tin-containing metal oxide
contains the tin element and the other metallic elements in
addition to tin, wherein said other metallic elements of the
addition of tin including antimony, indium, titanium, copper, zinc,
zirconium, cerium, yttrium, lanthanum, niobium, or mixtures
thereof, preferably from the elements antimony, indium or mixtures
thereof. In a preferred embodiment, the tin-containing metal oxide
can be antimony tin oxide or indium tin oxide.
[0013] For the nano-sized tin-containing metal oxide of this
invention, the preferred molar ratio of Sn to metal dopants is
between 1:0.01.about.1:100, and more preferably, between
1:0.05.about.1:50, or 1:0.05.about.1:20, for instance, 1:0.05,
1:0.1, 1:0.15, 1:0.2, 1:5, 1:10, 1:15, 1:20.
[0014] The tin-containing metal oxide nanoparticles of this
invention are crystallined with preferably tetragonal cassiterite
structure, bixbyite structure, tetragonal cassiterite-like
structure, or bixbyite-like structure.
[0015] Considering about the high transparency request of the thin
film made by tin-containing metal oxide based composite for its
application, the tin-containing metal oxide with low dimensionality
is preferred. Advantageously, the average primary particle diameter
of the tin-containing metal oxide nanoparticles stated in this
invention is 2.about.50 nm, or 2.about.20 nm, or 2.about.10 nm.
[0016] The index of dispersion degree/index of steepness herein are
measured from the said particles dispersion. The dispersibility of
the tin-containing metal oxide nanoparticles in this invention is
high in the dispersed medium, particularly for the mono-dispersion
with index of dispersion degree less than 7, and more particularly,
with the index of dispersion degree less than 5, or less than 4, or
less than 3, or less than 2. The tin-containing metal oxide
nanoparticles in this invention have a narrow particle diameter
distribution with preferred steepness ratio less than 3, and more
preferably, less than 2, or less than 1.8, or less than 1.5, or
less than 1.3.
[0017] In one embodiment, there is surfactant coating on the
surface of said tin-containing metal oxide nanoparticles.
[0018] According to a second aspect, there is provided a process of
making tin-containing metal oxide nanoparticles comprising the
steps of:
[0019] (1) Reacting a tin salt solution and doping metal salt
solution together with a precipitant solution to form the
tin-containing metal oxide precursor particles and the first ionic
by-product;
[0020] (2) Separating said tin-containing metal oxide precursor
particles and said first ionic by-product to obtain tin-containing
metal oxide precursor particles substantially free of said ionic
by-products;
[0021] (3) Reacting said tin-containing metal oxide precursor
particles substantially free of said ionic by-products with
oxidizing agent or reducing agent to form tin-containing metal
oxide particles and the second ionic by-product;
[0022] (4) Separating said tin-containing metal oxide particles and
said second ionic by-product to obtain tin-containing metal oxide
nanoparticles substantially free of said ionic by-products.
[0023] In one optimized embodiment, the said tin-containing metal
oxide nanoparticles are antimony-doped tin oxide nanoparticles. The
process of making said antimony-doped tin oxide nanoparticles
comprising the steps of:
[0024] (1) Reacting a tin salt solution and a antimony salt
solution together with a precipitant solution in an aqueous medium
phase at a pH of at least above 7 and at a temperature in the range
of about 5.about.100 degree Celsius to form antimony-doped tin
oxide precursor particles and the first ionic by-product;
[0025] (2) Separating said antimony-doped tin oxide precursor
particles and said first ionic by-product to obtain antimony-doped
tin oxide precursor particles substantially free of said ionic
by-products;
[0026] (3) Transferring said antimony-doped tin oxide precursor
particles substantially free of said ionic by-products into high
temperature high pressure reactor, and reacting with oxidizing
agent to form antimony-doped tin oxide particles and the second
ionic by-product;
[0027] (4) Separating said antimony-doped tin oxide particles and
said second ionic by-product to obtain antimony-doped tin oxide
nanoparticles substantially free of said ionic by-products.
[0028] In one optimized embodiment, the said tin-containing metal
oxide nanoparticles are indium-doped tin oxide nanoparticles. The
process of making said indium-doped tin oxide nanoparticles
comprising the steps of:
[0029] (1) Reacting a tin salt solution and a indium salt solution
together with a precipitant solution in an aqueous medium phase at
a pH of at least above 7 and at a temperature in the range of about
5.about.100 degree Celsius to form indium-doped tin oxide precursor
intermedia product and the first ionic by-product;
[0030] (2) Separating said indium-doped tin oxide precursor
particles and said first ionic by-product to obtain indium-doped
tin oxide precursor particles substantially free of said ionic
by-products;
[0031] (3) Transferring said indium-doped tin oxide precursor
particles substantially free of said ionic by-products into high
temperature high pressure reactor, and reacting with oxidizing
agent to form indium-doped tin oxide particles and the second ionic
by-product;
[0032] (4) Separating said indium-doped tin oxide particles and
said second ionic by-product to obtain indium-doped tin oxide
nanoparticles substantially free of said ionic by-products.
[0033] In one embodiment, in one or more steps of step (2), (3) and
(4), there is surfactant coating on the surface of said
tin-containing metal oxide precursor particles or tin-containing
metal oxide particles.
[0034] In one optimized embodiment, based on the weight of the
tin-containing metal oxide precursor particles or tin-containing
metal oxide particles, 0.01%.about.30% surfactants are added in one
or more steps of said step (2), (3) and (4).
[0035] According to a third aspect, there is provided a dispersion
of tin-containing metal oxide nanoparticles which including
disperse medium and tin-containing metal oxide nanoparticles as
defined in the first aspect.
[0036] In one embodiment, based on the weight of dispersion, the
solid content of said tin-containing metal oxide particles is at
least 5%, more advantageously, the solid content is at least 10%,
or at least 30%, or at least 40%, or at least 50%.
[0037] In one embodiment, the said disperse medium of said
dispersion choose from water, acetic ether, butyl acetate,
alcohols, alkene, aether, ketone, aromatic solvent and their
mixture.
[0038] In one embodiment, the said tin-containing metal oxide
nanoparticles of said dispersion have an index of dispersion degree
which is less than 7 and particle diameter distribution that is
defined by a steepness ratio of less than 3. More advantageously,
said index of dispersion degree is less than 5, or less than 4, or
less 3; and said steepness ratio is less than 2, or less than 1.8,
or less than 1.5, or less than 1.3.
[0039] In one embodiment, the average secondary particle diameter
of said tin-containing metal oxide nanoparticles of said dispersion
is between about 2 nm to about 100 nm, particularly, between about
2 nm to about 50 nm.
[0040] According to a forth aspect, there is provided a dispersion
of tin-containing metal oxide nanoparticles as defined in the third
aspect produced in a method comprising the steps of:
[0041] (1) Reacting a tin salt solution and doping metal salt
solution together with a precipitant solution to form the
tin-containing metal oxide precursor particles and the first ionic
by-product;
[0042] (2) Separating said tin-containing metal oxide precursor
particles and said first ionic by-product to obtain tin-containing
metal oxide precursor particles substantially free of said ionic
by-products;
[0043] (3) Reacting said tin-containing metal oxide precursor
particles substantially free of said ionic by-products with
oxidizing agent or reducing agent to form tin-containing metal
oxide particles and the second ionic by-product;
[0044] (4) Separating said tin-containing metal oxide particles and
said second ionic by-product to obtain tin-containing metal oxide
nanoparticles substantially free of said ionic by-products.
[0045] wherein, during one or more steps of step (2), (3) and (4),
coating the said tin-containing metal oxide precursor nanoparticles
or tin-containing metal oxide nanoparticles with a surfactant for
step (5); and
[0046] dispersing the tin-containing metal oxide nanoparticles into
the dispersion medium system to result in highly dispersed
dispersion of tin-containing metal oxide nanoparticles for step
(6).
[0047] According to a fifth aspect, there is provided another
dispersion of tin-containing metal oxide nanoparticles as defined
in the third aspect produced in a method comprising the steps
of:
[0048] (1) Reacting a tin salt solution and doping metal salt
solution together with a precipitant solution to form the
tin-containing metal oxide precursor particles and the first ionic
by-product;
[0049] (2) Separating said tin-containing metal oxide precursor
particles and said first ionic by-product to obtain tin-containing
metal oxide precursor particles substantially free of said ionic
by-products;
[0050] (3) Reacting said tin-containing metal oxide precursor
particles substantially free of said ionic by-products with
oxidizing agent or reducing agent to form tin-containing metal
oxide particles and the second ionic by-product;
[0051] (4) Separating said tin-containing metal oxide particles and
said second ionic by-product to obtain tin-containing metal oxide
nanoparticles substantially free of said ionic by-products.
[0052] (5) Dispersing tin-containing metal oxide nanoparticles into
the dispersion medium system again, and adjust pH value of the
system to result in highly dispersed dispersion of tin-containing
metal oxide nanoparticles.
[0053] In this invention, during the reaction of forming
tin-containing metal oxide by reacting general tin salt solution
and doping metal salt solution together with precipitant solution,
beside the tin-containing metal oxide precursor particles and
tin-containing metal oxide particles formed from the reaction of
tin ions and doping metal ions with the oxo-anions in the
precipitant, the soluble by-product of metal salt thereof is also
formed. As the reactions usually generate in an aqueous medium
phase, the by-product generally exist as ion form in the reaction
system. 4 mole of ionic by-product is formed to obtain 1 mole of
tin oxide as tin ions are tetravalent ions. During the reactions of
forming tin-containing metal oxide precursor particles or
tin-containing metal oxide particles, the surface energy of the
particles are very high as they are in nano-scale, then a lot of
the ionic by-products are quite easily to be adsorbed onto the
particle surface which lead the particles unstable in the disperse
medium and affect the dispersion stability and some other
properties. During experiments, it is found by the inventor that if
the ionic by-products and tin-containing metal oxide particles can
be effectively separated, it is possible to disperse the
tin-containing metal oxide particles into specific disperse medium
to make good dispersion with high solid content.
[0054] In the process of making nano-sized tin-containing metal
oxide in this invention, there are steps of choosing the amount of
tin ion solution and doping metal ion solution included which make
the molar ratio of metal dopant to tin of said tin-containing metal
oxide in the range of 1:0.01.about.1:100, more preferably, the
molar ratio is in the range of 1:0.05.about.1:50, or
1:0.05.about.1:20, for instance, the molar ratio of 1:0.05, 1:01,
1:0.15, 1:0.2, 1:5, 1:10, 1:15 or 1:20.
[0055] In the process in this invention, the said surfactants can
be added in any steps after the tin-containing metal oxide
precursor formation in step (1), which means coating the
tin-containing metal oxide precursor particles or tin-containing
metal oxide particles with surfactants during one or more steps of
step (2), (3) and (4). In one optimized embodiment, surfactant is
added in step (4).
[0056] In one embodiment, after obtaining the tin-containing metal
oxide particles and the ionic second by-product in step (3),
separating the tin-containing metal oxide particles and by-product
first and then adding dispersing agent to disperse the
tin-containing metal oxide particles to form needed dispersion of
tin-containing metal oxide particles in specific disperse
medium.
[0057] In one embodiment, adding specific amount of acid solution
during preparation of tin salt solution and doping metal salt
solution to improve dissolving of metal salt mixture.
[0058] As there is characteristic difference between the
tin-containing metal oxide particles (or tin-containing metal oxide
precursor particles) and the ionic by-product, they can be
separated effectively. In said separating step (2) and separating
step (4), the separating of tin-containing metal oxide particles
(or tin-containing metal oxide precursor particles) and the ionic
by-product process can be chosen from any one of the following
processes: liquid-liquid phase transfer, liquid-liquid phase
transfer after washing, centrifuge after washing, filtering after
washing. With any process, centrifuging for separation before
liquid-liquid phase transferring, liquid-liquid phase transferring
after washing, centrifuging after washing, filtering after washing
and then the obtained precipitates are substantially tin-containing
metal oxide particles (or tin-containing metal oxide precursor
particles).
[0059] In one embodiment, during separating the particles and ionic
by-product using liquid-liquid phase transfer, one of the aqueous
phase liquid and another organic phase liquid are immiscible. The
tin-containing metal oxide particles coated with surfactant are
induced into the organic phase and the ionic by-products are left
in the aqueous phase.
[0060] In one embodiment, separating the tin-containing metal oxide
particles and ionic by-product by washing. For instance, another
solvent will be added into the tin-containing metal oxide particle
suspension for the ionic by-product dissolving in this solvent to
make the tin-containing metal oxide particles stable. After
removing the medium/solvent system which dissolving the ionic
by-product from the tin-containing metal oxide particles, the
tin-containing metal oxide particles coated with surfactant can be
mono-dispersed in specific solvent.
[0061] During experiment, it is found that by the inventors the
surface property of the tin-containing metal oxide particles can be
modified by adding surfactant, and it is able to reduce or
eliminate the particle agglomeration effectively comparing to the
particles without surfactant coating. The most importance, choosing
the suitable surfactant and right time for adding surfactant make
the tin-containing metal oxide particles coated with certain amount
of surfactant have good compatibility with the disperse medium, and
achieve mono-disperse of tin-containing metal oxide particles in
the dispersion system with high solid content.
[0062] In one embodiment, the obtained tin-containing metal oxide
particles coated with surfactant are induced into the dispersion
solvent medium and separated from the ionic by-product to form
mono-dispersion of tin-containing metal oxide particles in above
mentioned solvent phase. More advantageously, the tin-containing
metal oxide particles coated with surfactant are not affected by
ionic by-products which lead agglomeration in the dispersion
solvent phase. Therefore, they are stabilized as mono-dispersion in
the solvent phase.
[0063] In one embodiment, after separating the tin-containing metal
oxide particles and the ionic by-products effectively and adding
the tin-containing metal oxide particles into disperse medium, the
highly dispersed dispersion of tin-containing metal oxide particles
can be obtained by adjusting the pH value of the system with adding
acid or alkali. For instance, during dispersing process, adding
certain amount of organic alkali, like tetra-methylammonium
hydroxide, to adjust pH to about 12.5 and make the dispersion as
transparent mono-dispersion system. Similarly, the pH value of the
mono-dispersion system can be adjusted between 0.about.14 according
to different applications.
[0064] In one embodiment, based on the weight of tin-containing
metal oxide nanoparticles dispersion, the solid content of said
tin-containing metal oxide nanoparticles achieved is at least 5%
without substantial agglomeration. More advantageously, the solid
content of tin-containing metal oxide nanoparticles in dispersion
achieved is at least 10%, or at least 25%, or at least 30%, or at
least 40%, or at least 50%. Therefore, the mono-dispersion of
tin-containing metal oxide particles produced by the said method in
this invention is possibly to achieve very high particle
content.
[0065] Surfactants can be expressed with formula of A-B. Group A is
able to be absorbed onto the surface of tin-containing metal oxide
particles and group B is solubilizing group (or called
compatibility group). Group A is able to attach to the surface of
tin-containing metal oxide particles through absorbing, formed
ionic bond, formed covalent bond, or cooperation effects thereof.
Group B can be active group or inactive group, and also can be
polar group or non-polar group.
[0066] In one embodiment, more than one type of surfactant may be
used. In this invention, the tin-containing metal oxide particles
may be coated with a first surfactant, and then after further
treatment, the corresponding groups of the first surfactant is at
least partially exchanged, or replaced with the second surfactant
to improve the compatibility of the tin-containing metal oxide
particles with solvent of the disperse medium and for the
enhancement of the dispersion of the tin-containing metal oxide
particles in disperse medium.
[0067] In one embodiment, the tin-containing metal oxide particles
coated with surfactant is further treated to at least partially
remove the by-products formed by the reaction of anions from metal
salt and cations from precipitant during synthesis process.
[0068] In one embodiment, the stability of the mono-dispersed
tin-containing metal oxide particles can be maintained at room
temperature and atmospheric pressure for at least 1 month without
substantial agglomeration.
[0069] In one embodiment, the aqueous phased dispersion produced
here can be fabricated as particle product which is in powder
form.
[0070] According to a sixth aspect, there is provided a dispersion
of nano-sized metal oxide composite which contains metal oxide
nanoparticles for UV blocking and the tin-containing metal oxide
nanoparticles for IR blocking. Particularly, the metal oxide
nanoparticles for UV blocking can be chosen at least one from zinc
oxide, titanium oxide, or cerium oxide.
[0071] In one embodiment, the zinc oxide, titanium oxide, or cerium
oxide particles for UV blocking may be obtained following the
method of patent PCT/SG 2008/00442, and the tin-containing metal
oxide nanoparticles are obtained following the method described in
the second aspect.
[0072] In one optimized embodiment, in the dispersion of metal
oxide nano-composite which contains tin-containing metal oxide and
zinc oxide (titanium oxide, and/or cerium oxide), based on the
weight of the dispersion, the solid content of said zinc oxide
(titanium oxide, and/or cerium oxide can be achieved to at least 5%
without substantial agglomeration. More advantageously, the solid
content of said zinc oxide (titanium oxide, and/or cerium oxide
achieved can be at least 10%, or at least 25%, or at least 30%, or
at least 40%, or at least 50%. Therefore, the stabilized dispersion
of the metal oxide nano-composite which can be used in glass
coating or shielding film for UV and IR blocking provided in this
invention may achieve very high particle content. It provides great
convenience and room for manoeuvre for the future formula recipe or
manufacturing of glass coating or shielding film.
[0073] In one embodiment, there is provided a dispersion of metal
oxide composite for UV and IR blocking in this invention wherein
the average secondary particle diameter of the metal oxide
nanoparticles for UV blocking is in the range of 2.about.100 nm,
which has the index of dispersion degree less than 7 and particle
distribution that is defined by a steepness ratio of less than
3.
[0074] According to a seventh aspect, there is provided a composite
material for sunlight controlling which contain the tin-containing
metal oxide nanoparticles, preferably as transparent and visible
coating or film, and more preferably as glass paint or film.
[0075] In one optimized embodiment, there is provided a glass
coating or glass shielding film which contains the tin-containing
metal oxide nanoparticles for IR blocking and metal oxide
nanoparticles for UV blocking.
[0076] According to an eighth aspect, there is provided a
transparent and visible material, which contains the tin-containing
metal oxide nanoparticles said in the first aspect, wherein the
tin-containing metal oxide nanoparticles exist on the surface of
and/or inside the said transparent and visible material.
[0077] In one optimized embodiment, the said tin-containing metal
oxide nanoparticles exist on the surface of said transparent and
visible material of the paint or film.
[0078] In one optimized embodiment, there is provided a glass
product in this invention for sunlight controlling. The glass
product is able to block UV and IR as its coating or shielding film
as defined in the seventh aspect to achieve the purpose of sunlight
controlling, energy saving and environment protection.
DEFINITIONS
[0079] The following words and terms used herein shall have the
meaning indicated:
[0080] The term "metal" as used herein, is to be interpreted
broadly to include all metals, including, for example, semimetals,
alkali metals, alkaline earth metals, transition metals and metals
selected from the main groups of the Periodic Table of
Elements.
[0081] The term "metal salt" is to be interpreted broadly to refer
to a compound comprised of at least one anion and at least one
cation. The anions and cations of the metal salt may be either
simple (monatomic) ions such as Na.sup.+, Ag.sup.+, Cu.sup.+,
Zn.sup.2+, Ca.sup.2+, Fe.sup.2+, Cu.sup.2+, Fe.sup.3+, Ce.sup.3+,
Al.sup.3+, Ce.sup.4+, Cl.sup.-, or complex (polyatomic) ions such
as CH.sub.3COO.sup.-, NO.sub.3.sup.2-, SO.sub.4.sup.2-. At least
one of the cations in the metal salt is a metal.
[0082] The term "metal salt solution" is to be interpreted broadly
to refer to a metal salt dissolved in a solvent, such as an aqueous
solvent, or an organic solvent (i.e. methanol, ethanol), or mixture
of aqueous and organic solvents, or a mixture of organic
solvents.
[0083] The term "precipitant solution", as used herein, is to be
interpreted broadly to include any solute dissolved in a solvent
that, when added to a metal salt solution, causes a precipitate to
form or crystals to grow. The precipitant may include alkaline
solutions such as an alkaline base, more particularly an
oxygen-containing base.
[0084] The term "oxygen-containing base" is to be interpreted
broadly to include any molecule or ion that contains an oxygen atom
which can form a bond with a metal ion by donating a pair of
electrons. Exemplary oxygen-containing bases include alkali metal
hydroxides (i.e. NaOH, LiOH, KOH), alkaline earth metal hydroxides
(i.e. Ca(OH).sub.2), an ammonia solution (i.e. NH.sub.4OH), alkali
metal carbonates (i.e. Na.sub.2CO.sub.3, K.sub.2CO.sub.3), alkali
hydrogen carbonates (i.e. NaHCO.sub.3, KHCO.sub.3), organic base
(i.e. (CH.sub.3).sub.4NOH) or a mixture thereof.
[0085] The term "nano" or "nano-sized" as used herein relates to an
average particle diameter of less than about 100 nm.
[0086] The term "narrow particle diameter distribution", as used
herein, is to be interpreted broadly to refer to a steepness ratio,
as measured on a SediGraph, of the precipitate particles being less
than about 3. The size distribution of the precipitate particles in
a given composition may be represented on a SediGraph which plots
cumulative mass percent as a function of particle diameter. Where
cumulative mass percent is the percent, by weight, of a
distribution having a particle diameter of less than or equal to a
given value and where particle diameter is the diameter of an
equivalent spherical particle. The mean particle diameter in a
distribution is the size in nanometers of the precipitate particles
at the 50% point on the SediGraph for that distribution. The width
of the particle diameter distribution of a given composition can be
characterized using a steepness ratio. As used herein, the
"steepness ratio" is defined as the average diameter of the
particles in the ninetieth mass percentile (d.sub.90) divided by
the average diameter of the particles in the tenth mass percentile
(d.sub.10).
[0087] The term "surfactant", as used herein, is to be interpreted
broadly to relate to any composition that is capable of altering
surface tension between a liquid and any precipitated particles
suspended in the liquid. Suitable surfactants are taught in
McCutcheon's Emulsifiers & Detergents, at pages 287-310 of the
North American Edition (1994), and in McCutcheon's Emulsifiers
& Detergents, at pages 257-278 and 280 of the International
Edition (1994), both published by MC Publishing Co. (McCutcheon
Division) of Glen Rock, N.J. "Dispersant" or "dispersing agent", as
used herein, is defined as an assistant agent which is able to
improve and modify the dispersibility of the precipitate particles
in medium. Dispersant is a type of surfactant. The types of
surfactant include anionic, cationic, non-ionic, amphoteric and
polymeric type.
[0088] The term "oxidizing agent" and "reducing agent" are to be
interpreted broadly as following: "oxidizing agent" is a substance
to gain electrons or have electron bias in oxidation-reduction
reaction, which means it is a substance with valence state change
from high to low during reaction. The oxidizing agent is reduced to
reduction product by gaining electrons from reducing agent. The
oxidizing agent and reducing agent are interdependent to each
other. "Reducing agent" is a substance to lose electrons or have
electron deviation in oxidation-reduction reaction. Reducing agent
is to be interpreted broadly as anti-oxidation agent. It has
reducibility, and become oxidation product after being oxidized.
Oxidation reaction and reduction reaction may be undertaken at the
same time, wherein the reduction reaction of reducing agent with
being reduced substance, the reducing agent is oxidized and become
oxide. The substance with valence state increasing during reaction
is reducing agent. Exemplary reducing agents include
ethylenediamine, oxalic acid, formalin, acetaldehyde, hydrazine
hydrate, sodium borohydride, metals, non-metals, i.e. Sn, H.sub.2,
C, etc. Exemplary oxidizing agents include peroxide, i.e.
Na.sub.2O.sub.2, K.sub.2O.sub.2, H.sub.2O.sub.2, peracetic acid,
etc.
[0089] The term "non-polar solvent" is to be interpreted broadly to
include an organic liquid in which the positive and negative
charges substantially coincide. Thus, a non-polar solvent does not
ionize or impart electrical conductivity. Exemplary non-polar
solvents include t-butylmethyl ether, methyl ether, and other
ethers of lower alkyl groups; aliphatic and aromatic hydrocarbons,
such as hexane, octane, cyclohexane, benzene, decane, toluene, and
the like; symmetrical halocarbons, such as carbon tetrachloride;
petroleum ether; and the like. Mixtures of non-polar liquids can be
used.
[0090] The term "polar solvent", which is contrary to "non-polar
solvent", is to be interpreted broadly to include a liquid in which
the positive and negative charge does not coincide. Thus, a polar
solvent ionize or impart electrical conductivity. Normally, a
solvent's polarity is determined roughly by the dielectric constant
of the solvent. Solvent with a dielectric constant more than 15 is
considered a polar solvent. Exemplary polar solvents include water,
alcohols such as acetone and methyl ethyl ketones; epoxides; and
ethyl acetate. Mixture of polar liquids can be used.
[0091] The term "aqueous medium" as used herein, is to be
interpreted broadly to include any medium which comprises water,
optionally in admixture with additional solvents such as organic
polar solvent. Exemplary organic polar solvents are alcohols,
amides, ketones, epoxides and mixture thereof. Typically, the
organic polar solvents have a relatively low number of carbon
atoms, such as about 1 to about 10 carbon atoms, or 1 to 6 carbon
atoms.
[0092] The term "ionic impurity" or "ionic by-product" is to be
interpreted broadly to the by-product in ionic form in reaction
system formed in the process of making tin-containing metal oxide
by reacting tin salt solution and doping metal salt solution
together with precipitants, i.e. Na.sup.+, K.sup.+, Cl.sup.-,
NH.sup.4+, NO.sub.3.sup.-, CH.sub.3COO.sup.-, SO.sub.4.sup.2-,
small amount of Sn.sup.4+, Sb.sup.3+, In.sup.3+, and other doping
metal ions without complete hydrolysis containing tin, antimony or
indium.
[0093] The term "liquid-liquid phase transfer" is to be interpreted
broadly to include the preferential movement of solutes, residues,
or any matter of interest into one of an immiscible pair of liquid
phases.
[0094] The term "washing" is to be interpreted broadly to add
aqueous medium into the system containing precipitate particles to
dissolve or further dissolve the ionic by-products in the system
containing precipitate particles to achieve effective separation of
the ionic by-products and the precipitate particles through post
phase transfer, centrifuge or filer of the ionic by-products.
[0095] The term "average primary particle diameter", is related to
the average particle diameter before dispersion of the metal oxide
particles in disperse medium. Normally, it is measured (d.sub.TEM)
by Transmission Electron Microscopy (TEM).
[0096] The term "average secondary particle diameter" relate to
average primary particle diameter, which is the average particle
diameter after dispersion of the metal oxide particles in disperse
medium. Normally, it is measured (d.sub.DLS) by Dynamic Light
Scattering instrument (DLS).
[0097] The term "monodispersion" as used herein, in conjunction
with metal oxide particles, is to be interpreted broadly to refer
to an index of dispersion degree of metal oxide particles in liquid
medium. In general, the "index of dispersion degree" is defined as
the average particle diameter of the secondary (or aggregated)
particles divided by the average primary particle diameter of the
particles. Therefore, the smaller the index of the dispersion
degree, the closer the dispersion is to a monodispersion.
Typically, a monodispersion may have an index of dispersion degree
of less than 7 and no less than 1. Generally, the term
"monodispersion" means that the particles loaded in the liquid
medium do not substantially agglomerate or clump together with
other particles but remain substantially dispersed in the liquid
medium.
[0098] The word "substantially" does not exclude "completely" e.g.
a composition which is "substantially free" from Y may be
completely free from Y. Where necessary, the word "substantially"
may be omitted from the definition of the invention.
[0099] The term "comprising" and "comprise", are intended to
represent "open" or "inclusive" language such that they include
recited elements but also permit inclusion of additional, unrecited
elements,
[0100] As used herein, the term "about", in the context of
concentrations of components of the formulations, typically means
+/-5% of the stated value, more typically +/-4% the stated value,
more typically +/-3% the stated value, more typically +/-3% the
stated value, even more typically +/-1% the stated value, and even
more typically +/-0.5% the stated value.
[0101] Throughout this disclosure, certain embodiments may be
disclosed in a range format. It should be understood that the
description in range format is merely for convenience and brevity
and should not be construed as an inflexible limitation on the
scope of the disclosed ranges. Accordingly, the description of a
range should be considered to have specifically disclosed all the
possible sub-ranges as well as individual numerical values within
that range. For example, description of a range such as from 1 to 6
should be considered to have specifically disclosed sub-ranges such
as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6,
from 3 to 6 etc., as well as individual numbers within that range,
for example, 1, 2, 3, 4, 5 and 6. This applies regardless of the
breadth of the range.
DETAILED DISCLOSURE OF EMBODIMENTS
[0102] Exemplary, non-limiting embodiments of a process of making
dispersion of nano-sized tin-containing metal oxide for glass paint
or shielding film for IR blocking are disclosed. The process
comprising the steps of:
[0103] (1) Reacting a tin salt solution and a doping metal (i.e.
Sb, In) salt solution with a precipitant solution under conditions
to form tin-containing metal oxide precursor particles and first
ionic by-product;
[0104] (2) Separating said tin-containing metal oxide precursor
particles and said first ionic by-product to obtain tin-containing
metal oxide precursor particles substantially free of said ionic
by-products;
[0105] (3) Transferring said tin-containing metal oxide precursor
particles substantially free of said ionic by-products into high
temperature high pressure reactor, and reacting with oxidizing
agent or reducing agent under high temperature and high pressure
condition for certain time, to form tin-containing metal oxide
particles and the second ionic by-product;
[0106] (4) Coating said tin-containing metal oxide particles with a
surfactant;
[0107] (5) Separating said surfactant coated tin-containing metal
oxide particles and said second ionic by-product to obtain
tin-containing metal oxide nanoparticles substantially free of said
ionic by-products;
[0108] (6) Dispersing the said surfactant coated tin-containing
metal oxide particles substantially free of said ionic by-products
into selected disperse medium system to obtain dispersion of
nano-sized tin-containing metal oxide with high dispersion;
[0109] (7) Comprising the dispersion of nano-sized tin-containing
metal oxide and nano-sized zinc oxide (titanium oxide, and/or
cerium oxide) in the same solvent medium to obtain stabilized
dispersion of metal oxide nano-composite for both UV and IR
blocking.
[0110] In one embodiment, the tin salt and/or metal salt for making
nano-sized tin-containing metal oxide may be selected from the
group consisting of a metal acetate salt, a metal halide salt, a
metal nitrate salt, a metal phosphate salt, a metal sulphate salt,
a metal chlorate salt, a metal borate salt, a metal iodate salt, a
metal carbonate salt, a metal perchlorate salt, a metal tartrate
salt, a metal formate salt, a metal gluconate salt, a metal lactate
salt, a metal sulfamate salt, hydrates and mixture thereof.
[0111] In one embodiment, the precipitant solution may be a base
solution. The base solution may be an oxygen-containing base
solution. The oxygen-containing base solution may be selected from
the group consisting of alkali metal hydroxides, alkaline earth
metal hydroxides, alkali metal carbonates, alkaline earth metal
carbonates, alkaline earth metal hydrogen carbonates, ammonia,
organic base and mixture thereof. Exemplary oxygen-containing bases
are solution of LiOH, NaOH, KOH, NH.sub.3.H.sub.2O, Be(OH).sub.2,
Mg(OH).sub.2, Ca(OH).sub.2, Li.sub.2CO.sub.3, Na.sub.2CO.sub.3,
K.sub.2CO.sub.3, KHCO.sub.3, (CH.sub.3).sub.4NOH or mixtures
thereof. It is to be appreciated that the base solution may be used
to control the pH during the reacting step. This may substantially
minimize the need to stop the reaction half-way in order to adjust
the pH to a desired value to simplify the process.
[0112] The base solution can be formed by dissolving a base (i.e.
such as NaOH or KOH) solid in a solvent. The solvent may include
water, an organic liquid (i.e. such as alcohol) or mixtures
thereof.
[0113] The reacting step in step (1) for making tin-containing
metal oxide precursors may be undertaken in an open chamber or an
enclosed chamber. The reacting step may be undertaken at a
temperature of less than or about 100 degrees Celsius. The reacting
step may be undertaken at a temperature in the range of about 5 to
about 100 degrees Celsius. In one embodiment, the reacting
temperature is in the range of about 50 to about 80 degrees
Celsius. The reacting step is undertaken at atmospheric pressure
and the reacting step is undertaken for time duration of less than
about 90 minutes. In one embodiment, the time required for the
reacting step is about 60 minutes or less. In another embodiment,
the time required for the reacting step is less than about 20
minutes. In a further embodiment, the time required for the
reacting step is less than about 10 minutes. The reacting step for
forming tin-containing metal oxide precursors may be undertaken in
non-acidic conditions, which means the reacting step may be
undertaken in substantially neutral or substantially alkaline
conditions.
[0114] The precipitation reacting step in step (1) need to choose
suitable amount of tin salt solution and doping metal salt solution
to make the molar ratio of the metal dopant to tin in the
tin-containing metal oxide in the range of about 0.01 to about 100,
or about 0.05 to about 50, or about 0.05 to about 20, or about 0.1
to about 10. In one embodiment, the molar ratio of the metal dopant
to tin in the tin-containing metal oxide is in the range of 0.05 to
19.
[0115] In one embodiment, the precipitation reacting step in step
(1) is undertaken in substantially alkaline conditions. In another
embodiment, the reacting step is undertaken at a pH in the range of
at least about 7.0 or at least about 8.5 or at least about 10. In
another embodiment, the reacting step is undertaken at a pH in the
range of about 8.5 to about 9.5. It is to be appreciated that an
alkaline condition may aid in the formation of tin-containing metal
oxide precursors.
[0116] In one embodiment, the reacting step for tin-containing
metal oxide formation may be undertaken in a substantially polar
phase. The polar phase may be an aqueous medium phase. The aqueous
medium may be comprised of at least one of water, alcohols, amides,
ketones, epoxides or mixtures thereof. The alcohols may be
methanol, ethanol, isopropanol or n-propanol.
[0117] In one embodiment, the starting pH value of the tin salt
solution and doping metal salt solution (i.e. Sb, In) may be
adjusted by addition of acid or alkaline into the aqueous
medium.
[0118] The separation of tin-containing metal oxide precursors and
the by-products is undertaken by phase transfer, phase transfer
after washing, centrifuge after washing, or filtering after washing
of the tin-containing metal oxide precursors particles and the
ionic by-products formed from reaction of tin salt solution and
doping metal (i.e. Sb, In) salt solution with precipitant solution
to achieve the purpose of separation.
[0119] The high temperature high pressure hydrothermal reacting
step in step (3) described above is undertaken in an enclosed
chamber. The reacting step is undertaken at a temperature of more
than 100 degree Celsius and at a pressure in the range of 1 to 20
atmospheres. The pressure is normally self-generated by the
solution system under enclosed chamber and heating condition. In
one of the embodiment, the reacting step is undertaken at a
temperature in the range of about 150 to about 400 degree Celsius
and at a pressure in the range of about 5 to about 10 atmospheres.
In another embodiment, the reacting step is undertaken at a
temperature in the range of about 200 to about 400 degree Celsius.
In a further embodiment, the reacting step is undertaken at a
temperature in the range of about 300 to about 400 degree Celsius
and for time duration of more than about 1 hour. In one embodiment,
the time required of the reacting step is about or less than about
3 hours. In another embodiment, the time required of the reacting
step is more than about 8 hours. In a further embodiment, the time
required of the reacting step is more than about 10 hours.
[0120] In step (4) the surfactant can be selected from the group
consisting of: anionic surfactants, cationic surfactants, non-ionic
surfactants, polymeric surfactants and mixtures thereof. The
surfactant selected herein may comprise of silane coupling agents,
non-silane surface modifying agents, titanate coupling agents, or
mixtures thereof.
[0121] Exemplary surfactants are silane coupling agents. Silane
coupling agents are a type of silicon-containing organic compound
which may be represented by the formula YSiX.sub.3, where X is
alkyl group or alkoxy group, and where Y is alkyl group, oxoalkyl
group, amino group or phenyl group, etc. Silane coupling agents may
improve the compatibility between organic and inorganic compound,
they may also improve and enhance the physical chemical properties,
like strength, toughness, electrical properties, water resistance,
and corrosion resistance, of composite materials. Exemplary silane
coupling agents are include, but not limited to, Trialkoxy silane,
(Methyl) acryloxy-alkoxy-trialkoxy silane,
Acryloyloxy-alkoxy-trialkoxy silane, (Methyl)
acryloyloxy-alkyl-alkyl-dialkoxy silane,
Acryloyloxy-alkyl-alkyl-dialkoxy silane, (Methyl)
acryloyloxy-alkyl-dialkyl-alkoxy silane,
Acryloyloxy-alkyl-dialkyl-alkoxy silane, Thiol-alkoxy-trialkoxy
silane, .gamma.-Methacryloxypropyltrimethoxy silane, Aryl-trialkoxy
silane, Vinyl silane, 3-Glycidyloxypropyl-trialkoxy silane,
Polyether silanes, .gamma.-Aminopropyl-triethoxy silane,
.gamma.-Glycidyloxypropyltrimethoxy silane,
.gamma.-(Methacryloyloxy) propyl-trimethoxy silane,
.gamma.-Mercaptopropyltrimethoxy silane,
.gamma.-Aminoethyl-aminopropyl-trimethoxy silane,
Bis-propyl-triethoxy silane,
N-(.beta.-Aminoethyl)-.gamma.-(aminopropyl)-methylbimethoxy silane,
N-(.beta.-Aminoethyl)-.gamma.-(aminopropyl)-trimethoxy silane,
.gamma.-Aminoethyl-aminopropyl-trimethoxy silane,
Hexadecyltrimethoxy silane, combinations thereof.
[0122] Non-silane surface modifying agents reactive and compatible
with organic matrix material include, for example, sodium dodecyl
sulphate, sodium lauryl sulphate, sodium laurate, sodium oleate,
sodium naphthenate, sodium stearate, sodium abietate, sodium
iso-octoate, sodium linoleate, sodium caproate, sodium ricinate,
ethyl acetate, sodium acetate, dioctylsodium sulphosuccinate,
TWEEN.RTM. (polyoxyethylene sorbitan monooleate), SPAN 80.RTM.
(sorbitan monooleate), SPAN 85.RTM. (sorbitan trioleate),
PLURONIC.RTM., polysorbate, N-polyvinyl pyrrolidone, polyethylene
glycol, polyoxyethylene, bis-2 hydroxyethyl oleyl amine,
hexadecyltrimethyl ammonium bromide, hydroxypropyl cellulose,
hydroxypropylmethyl cellulose, maltose sugar, sucrose, citric acid,
ethylene glycol, acrylic acid, methacrylic acid, (3-hydroxyethyl
acrylate, tetraethyl orthosilicate and mixtures thereof.
[0123] There are four types of titanate coupling agents including:
monoalkoxy type, pyrophosphate type, chelating type and
coordinating type. Titanate coupling agents may be represented by
formula ROO.sub.(4-n)Ti(OX-- R'Y).sub.n (n=2, 3), where RO-- is
alkoxy group with short chain which is able to be hydrolysis, and
reactive with hydroxyl group on the surface of inorganic compound
to achieve chemical coupling; where OX-- may be carboxyl group,
alkoxy group, sulfonic acid group, phosphate group, etc. These
groups are important to decide the specific function of titanate
coupling agents, for example, sulfonic acid group may induce the
thixotropy of the organic compound, and pyrophosphate acyloxy
groups have the properties of flame resistance, anti-rust and
adhesion enhancement. Phosphorous acyloxy groups may provide
properties of antioxidant, flame resistance, etc. Therefore, the
titanate coupling agents may have both coupling property and other
specific functions by OX-- selection; R'-- is alkyl group with long
chain, it is soft and may be bended and entangle with organic
polymers to modify the compatibility between organic and inorganic
compound and improve the strength of impact resistance of the
material; Y is hydroxyl group, amino group, epoxy group or groups
with double bond, etc. These groups connect to the end of the
titanate molecules, and may be bonded with organic compound by
chemical reaction. Titanate coupling agents have both great
flexibility and multi-functionality. They may be coupling agent
themselves, and also may be dispersion agent, wetting agent,
adhesion agent, crosslinking agent, catalyst, etc. Titanate
coupling agents also have the functions of anti-rust,
antioxidation, flame resistance, etc.
[0124] When the surfactant is used for dispersion, the surfactant
selection is based on the following conditions: if the dispersion
of tin-containing metal oxide is formed with water as the disperse
medium, the dispersing agents may be selected from: ethanolamine,
triethanolamine, triethylamine, diisopropanolamine,
tetramethylammonium hydroxide, sodium metaphosphate, sodium
hexametaphosphate, polyvinyl alcohol, methacryloxy silane,
polyacrylic acid ammonium salt dispersing agent, polyacrylic acid
sodium salt dispersing agent, polysiloxane dispersing agent,
polyamide dispersing agent, polymeric block copolymer, more
mixtures thereof; if the dispersion of tin-containing metal oxide
is formed with organic solvent as the disperse medium, the
dispersing agents may be selected from: polycarboxylic salt
dispersing agent, polycarboxylic-sulfonic copolymer dispersing
agent, polymaleicanhydride copolymer dispersing agent, silane
coupling agent, titanate coupling agent, or mixtures thereof.
[0125] The coating step in step (4) may comprise the step of
selecting the concentration of the surfactant based on the mass of
tin-containing metal oxide from the group consisting of: about
0.01% to about 30%; about 0.01% to about 20%; about 0.01% to about
10%; about 0.01% to about 5%; about 0.01% to about 1%; about 0.1%
to about 30%; about 0.5% to about 30%; about 1% to about 30%; about
5% to about 10%; about 0.1% to about 5%. In one embodiment, the
mass concentration of the surfactant is selected in the range of
about 0.01% to about 30%.
[0126] The surfactant may bind to the tin-containing metal oxide
particles in its supplied form or may undergo a chemical reaction
such as hydrolysis before binding to the tin-containing metal oxide
particles. The binding of surfactant or the derived product of the
surfactant to the tin-containing metal oxide particles may be
reversible or irreversible. In one embodiment, the binding may be
caused by intermolecular interactions selected from the group
consisting of ion-ion interactions, Van der waals forces of
attraction, hydrophobic interactions, dipole-dipole interactions,
covalent bonding or a combination thereof. In another embodiment,
the binding may result in the tin-containing metal oxide particles
being completely or incompletely coated by the surfactant or its
derivative.
[0127] The tin-containing metal oxide particles are coated or
modified to improve their compatibility to organic matrix (such as
polymers), and then to achieve a compound consisting of both
tin-containing metal oxide particles and zinc oxide (titanium
oxide, and/or cerium oxide) for application of glass paint or
shielding film in organic matrix to block UV and IR and to make the
glass highly transparent and energy conservation. The compatibility
of the tin-containing metal oxide particles to the organic matrix
materials of the final dispersion product is decide by the solvent
type used during separating step. For example, if organic solvent
is used in separating step, the polymers may be include, but not
limited to, polystyrene, polymethyl methacrylate, polycarbonate,
polyurethane, etc.; if polar solvent is used in separating step,
the polymers may be include, but not limited to, polyvinyl acetate,
polyvinyl butyral, etc.
[0128] In one embodiment, an organic solvent may be added to the
surfactant coated the tin-containing metal oxide particles to
result in a two-phase system comprising an organic medium phase and
an aqueous medium phase that may be partially or completely
immiscible with each other. The organic medium phase may be
selected from the group consisting of alkanes, alkenes, ethers,
ketones, and aromatic solvents. In one embodiment, the organic
medium phase is a non-polar organic solvent, such as toluene, or an
alkane such as heptane, hexane, octane, or decane.
[0129] The surfactant coated tin-containing metal oxide particles
may report to the organic phase while the ionic by-products remain
in the aqueous phase. Hence, the ionic by-products may be separated
from the tin-containing metal oxide particles via liquid-liquid
phase transfer.
[0130] The surfactant may be selected such that the surfactant
coated tin-containing metal oxide particles have a higher affinity
for the organic medium phase relative to the aqueous medium phase.
The inventors have found that the use of surfactants may aid in the
preferential movement of the surfactant coated tin-containing metal
oxide particles to the organic phase. While not intending to be
bound by theory, this phenomenon may be due to the alteration of
the surface properties of the tin-containing metal oxide particles
as they are coated with the surfactant such that the surfactant
coated tin-containing metal oxide particles are relatively more
hydrophobic than tin-containing metal oxide particles not coated
with the surfactant.
[0131] In one embodiment, the surfactant is selected such that a
monodispersion of the tin-containing metal oxide particles is
formed. Preferably, the selected surfactant comprises of a
stearically large organic group. The inventors have found that the
coating of the surfactant on the particles may aid in the formation
of a monodispersed tin-containing metal oxide in the organic phase.
Without being bound by theory, this may be due to the stearic
hindrance between the organic groups of the surfactant coated
tin-containing metal oxide particles which may aid in effectively
keeping the tin-containing metal oxide particles from coagulating
together. Furthermore, the surfactant may be selected to enable the
tin-containing metal oxide particles to report to the organic
medium phase while the ionic by-products remain in the aqueous
phase.
[0132] In another embodiment, an aqueous medium may be added into
the surfactant coated tin-containing metal oxide particles to
substantially dissolve ionic by-products. The tin-containing metal
oxide particles settle to the bottom of the reaction mixture and
can be separated from the by-products via centrifugation or any
other physical separation process such as filtration. The
by-products remain in the supernatant and are decanted after
centrifugation. The tin-containing metal oxide particles can be
re-dispersed to form a monodispersion in the polar medium. The
polar medium phase may be selected from the group consisting of
water, ethyl acetate, alcohols and ketone solvents.
[0133] The solid content of the monodispersion of the
tin-containing metal oxide particles may be at least about 5%, or
at least about 25%, or at least about 30%, or at least about 40%,
or at least about 50% by weight. Accordingly, a high concentration
of the tin-containing metal oxide particles may be present in the
monodispersion.
[0134] In one embodiment, the tin-containing metal oxide particles
are antimony-doped tin oxide or indium-doped tin oxide.
[0135] The tin-containing metal oxide particles may have an average
secondary particle diameter of about 2 nm to about 100 nm; about 2
nm to about 50 nm; about 5 nm to about 50 nm; about 10 nm to about
100 nm; about 50 nm to about 100 nm; about 2 nm to about 100 nm.
The tin-containing metal oxide particles may have a narrow particle
diameter distribution in that the steepness ratio of the final
tin-containing metal oxide particles in dispersion is less than
about 3, or less than about 2, or less than about 1.8, or less than
about 1.5, or less than about 1.3. The tin-containing metal oxide
particles are substantially monodispersed and may have an index of
dispersion degree less than about 7, or less than about 5, or less
than about 4, or less than about 3, or less than about 2.
[0136] The process may comprise after the separating step in step
(2) and (5), the step of washing the tin-containing metal oxide
particles (or tin-containing metal oxide particle precursors) with
an aqueous medium. The step of washing the tin-containing metal
oxide particles with aqueous medium may remove any unwanted
by-products that may be ionic in nature that have not been
completely removed in separating step. The removal of unwanted
by-products may aid in increasing the stability of the
monodispersion of tin-containing metal oxide particles.
[0137] The aqueous medium used during the washing step may be the
same or may be different than that used during the reacting step.
In the washing step, the aqueous medium may be selected from water,
alcohols, amides, ketones, epoxides, or mixtures thereof. In one
optimized embodiment, one or more alcohols selected from the group
consisting of methanol, ethanol, propanol, isopropanol, n-propanol
and mixture thereof may be in admixture with the water. In one
embodiment, the volume amount of alcohol relative to water solvent
may be in the range selected from the group consisting of about 1%
to about 99%; about 10% to about 99%; about 20% to about 99%; about
30% to about 99%; about 40% to about 99%; about 50% to about 99%;
about 60% to about 99%; about 70% to about 99%; about 80% to about
99%; about 90% to about 99%.
[0138] The washing aqueous medium added to the organic phase medium
may be at least partially miscible with the reaction medium
comprising the tin-containing metal oxide particles. The
tin-containing metal oxide particles in the above mixed medium may
precipitate out from the mixed medium. The tin-containing metal
oxide particles can be separated by centrifuging and washed again
with aqueous medium.
[0139] In some embodiments, it may be necessary to re-disperse the
formed tin-containing metal oxide particles in dispersion medium.
The dispersion medium may be selected from the group consisting of
water, ethyl acetate, butyl acetate, alcohols, alkenes, ethers,
ketones, aromatic solvents, and mixtures thereof. More
particularly, the dispersion medium may be selected from, but not
limited to, the group consisting of water, ethyl acetate, butyl
acetate, butyl ester, toluene, and ethanol.
[0140] The type of dispersion medium chosen may be dependent on the
type of the end-product required. For example, if the end-product
requires the use of a polar solvent, the tin-containing metal oxide
particles may be re-dispersed in a polar solvent. Alternatively, if
the end-product requires the use of a non-polar solvent, the
tin-containing metal oxide particles may be re-dispersed in a
non-polar solvent.
[0141] In reacting step (1) or (3), during both of the process of
reacting step to form tin-containing metal oxide particle
precursors and the process of hydrothermal under high temperature
and high pressure condition to form tin-containing metal oxide
particles, a shear force may be applied to the mixture of metal
salt solution and precipitant solution to form tin-containing metal
oxide particles with small particle diameter, and have a narrow
particle diameter distribution characterized in that the steepness
ratio is less than about 3, or less than about 2, or less than
about 1.9, or less than about 1.8, or less than about 1.7, or less
than about 1.6, or less than about 1.5, or less than about 1.3.
[0142] The monodispersing of the tin-containing metal oxide
particles is defined with the index of dispersion degree is less
than about 7, or less than about 5, or less than about 3, or less
than about 2, or less than about 1.2.
[0143] The process may further comprise the step of agitating the
solution during the reacting step to induce the shear force. The
shear force induced may have a Reynolds number in the range
selected from the group consisting of 2000-200000, 5000-150000, and
8000-100000. The substantially high Reynolds number may enable a
high degree of mixing in said reaction zone. In one embodiment, the
agitating step to induce the shear force during the reacting step
may be provided by an agitator and shearing means as previously
disclosed in the International Patent Application number
PCT/SG02/00061, the disclosure of which is herein incorporated as
reference.
BRIEF DESCRIPTION OF DRAWING
[0144] The accompany drawing illustrate a disclosed embodiment and
serves to explain the principles of the disclosed embodiment. It is
to be understood, however, that the drawings are designed for
purposes of illustration only, and not as a definition of the
limits of the invention.
[0145] FIG. 1 is optimized schematic diagrams of the flow chart
described in this invention, wherein FIG. 1A is the schematic
diagrams of the flow chart for implementing the process for the
production of tin-containing metal oxide particles and their
dispersion, and FIG. 1B is the schematic diagrams of the flow chart
for implementing the process for the further production of
dispersion of nano-sized metal oxide composite.
[0146] FIG. 2 shows the high resolution transmission electron
microscope (HRTEM) images of monodispersed ATO nanoparticles
prepared in example 1 below. FIG. 2A was obtained at 50 k
magnification and FIG. 2B was obtained at 500 k magnification.
[0147] FIG. 3 shows a dynamic light scattering (DLS) pattern of the
monodispersed ATO nanoparticles prepared in example 1 below.
[0148] FIG. 4 shows the HRTEM images of monodispersed ATO
nanoparticles prepared in example 3 below. It was obtained at 50 k
magnification.
[0149] FIG. 5 shows an X-ray Diffraction (XRD) pattern of
monodispersed ATO nanoparticles prepared in example 3 below.
[0150] FIG. 3 shows a DLS pattern of the monodispersed ATO
nanoparticles prepared in example 3 below.
[0151] FIG. 7 shows the HRTEM images of monodispersed ATO
nanoparticles prepared in example 4 below. FIG. 7A was obtained at
50 k magnification and FIG. 7B was obtained at 500 k
magnification.
[0152] FIG. 8 shows the HRTEM images of monodispersed ATO
nanoparticles prepared in example 6 below. FIG. 8A was obtained at
50 k magnification and FIG. 8B was obtained at 500 k
magnification.
[0153] FIG. 9 shows the UV-Vis-NIR spectrum of ATO nanoparticles
with different antimony doping levels dispersed in water with 5% of
solid content prepared in example 7 below.
[0154] FIG. 10 shows the UV-Vis-NIR spectrum of ATO nanoparticles
dispersed in water with different solid content prepared in example
8 below.
[0155] FIG. 11 shows the UV spectrum of ATO nanoparticles and
ATO+CeO.sub.2 or ATO+ZnO metal oxide nanoparticles composite
dispersed in water with 5% of solid content prepared in example 9
below.
[0156] FIG. 12 shows the UV-Vis-NIR spectrum of glass coated by
aqueous acrylic acid paint containing ATO nanoparticles or ATO+ZnO
nanoparticles using dip-coating method or gravity-coating method in
example 10 below. FIG. 12A shows the UV part of the spectrum, and
FIG. 12B shows the whole spectrum.
DETAILED DESCRIPTION OF DRAWINGS
[0157] Referring to FIG. 1A, there is provided a process for the
preparation of the dispersion of other metal-doped tin oxide. In
the first step, a mixed metal salts solution (12) formed by mixing
tin salt solution and other metal salt solution (such as mixed salt
solution of tin chloride and antimony chloride) is mixed with a
precipitant solution (14), which is alkali (such as potassium
hydroxide, sodium hydroxide or ammonia solution). The precipitating
reaction is carried out in a reaction zone (10) which may be a
beaker, a flask or a reactor. A shear force is applied to the
mixture during the mixing and reacting step. The reaction zone (10)
is typically maintained at a temperature of between 5 degrees
Celsius to 95 degrees Celsius, at atmospheric pressure and at a pH
of 7.5 to 10. Within the reaction zone (10), the tin-containing
metal oxide precursor particles and the by-products thereof are
formed.
[0158] The separation of the tin-containing metal oxide precursor
particles and the by-products thereof is carried out during the
separating step (20) to remove the ionic by-products (22). In the
high temperature and high pressure reaction zone (30), both
tin-containing metal oxide precursor particles and oxidizing agents
(or reducing agents based on the requirement of the doping agent)
are added, for antimony-doped tin oxide, normally oxidizing agent
is required and for indium-doped tin oxide, normally reducing agent
is required. The reacting step to the tin-containing metal oxide
precursor solution is maintained for a certain time under high
temperature and high pressure condition, and a shear force is
applied to the mixture to ensure the uniformly formation of the
tin-containing metal oxide crystalline particles. The high
temperature and high pressure reaction zone is typically maintained
at a temperature of between 120 degrees Celsius to 500 degrees
Celsius and at a pressure of between 1 atmosphere to 20
atmospheres.
[0159] The suspension of tin-containing metal oxide is taken from
the high temperature and high pressure reaction zone, and a
surfactant (42) is added for coating (40) of the tin-containing
metal oxide particles. The surfactant may be selected from, but not
limited to, the group consisting of oleic acid, sodium oleate,
sodium abietate, sodium stearate, sodium octoate, sodium linoleate,
hexadecyltrimethyl ammonium bromide, silane coupling agent,
titanate coupling agent, sugar, ethylene glycol, maltose, citric
acid, sodium citrate or mixtures thereof.
[0160] After the coating step, the ionic by-products in the
tin-containing metal oxide crystalline particles are removed during
a separating step (50) such as phase transfer, or washing methods,
etc.
[0161] Optionally, a dispersing agent is added to the
tin-containing metal oxide crystalline particles after removing the
ionic by-products for further dispersion. For dispersing agent
selection, if the disperse medium is water, one or more dispersing
agents may be selected from, but not limited to, the group
consisting of: ethanolamine, triethanolamine, triethylamine,
diisopropanol amine, tetramethylammonium hydroxide, sodium
metaphosphate, sodium hexametaphosphate, polyvinyl alcohol,
methacryloxy silane, polyacrylic acid ammonium salt dispersing
agent, polyacrylic acid sodium salt dispersing agent, polysiloxane
dispersing agent, polyamide dispersing agent, polymer block
copolymer dispersing agent; if the disperse medium is an organic
solvent, one or more dispersing agents may be selected from, but
not limited to, the group consisting of: polycarboxylic salt
dispersing agent, polycarboxylic-sulfonic copolymer dispersing
agent, polymaleicanhydride copolymer dispersing agent, silane
coupling agent, titanate coupling agent. The concentration of the
surfactants and dispersing agents mentioned above is in the range
of about 5% to about 20% based on the weight of tin-containing
metal oxide particles.
[0162] After that, the tin-containing metal oxide crystalline
nanoparticles may be dried by traditional methods (such as oven
drying, spray drying, rotary-evaporation drying, etc.) to form
tin-containing metal oxide powder product (55), or added into
disperse medium (62) for dispersing (60) to produce dispersion of
nano-sized tin-containing metal oxide (65).
[0163] Optionally, if the disperse medium is water, the dispersion
of tin-containing metal oxide particles in aqueous phase may be
obtained by adjusting the pH value of the dispersion.
[0164] Referring to FIG. 1B, a disperse medium (80) is further used
for mixing (80) of tin-containing metal oxide nanoparticles (55) or
their dispersion (65) prepared according to FIG. 1A which may block
IR and nano-sized metal oxide such as zinc oxide, titanium oxide
and cerium oxide nanoparticle (72) or their dispersions (74) with
good compatibility which may block UV to form a dispersion of metal
oxide composite (80) for both UV and IR blocking.
[0165] In one embodiment, an organic solvent, such as hexane, is
added to the mixture of tin-containing metal oxide crystalline
particles after modified by surfactants and ionic by-products.
[0166] For example, in a reaction to produce antimony-doped tin
oxide (ATO) from SnCl.sub.4 and SbCl.sub.3 mixed metal salt
solution (12) and ammonia solution as precipitant solution (14),
the ionic by-products may include Cl.sup.-, NH.sub.4.sup.+, small
amount of Sn.sup.4+, Sb.sup.3+ and ions without completely
hydrolysed containing tin and antimony. During the process of
separating the antimony-doped tin oxide crystalline particles and
the ionic by-products, the phase transfer method is used normally
as the tin-containing metal oxide crystalline particles coated with
specific surfactant are easily to be dissolved in organic phase,
hence after adding the organic solvent, the tin-containing metal
oxide crystalline particles are completely dissolved or suspended
as monodispersion in the organic phase, while the ionic by-products
are remained in the aqueous phase solution.
[0167] An immiscible mixture of an organic phase medium an aqueous
phase medium is formed. The aqueous phase medium containing the
ionic by-products may be separated from the organic phase medium by
liquid-liquid phase separating apparatus (such as a separating
funnel).
[0168] In another embodiment, an aqueous medium is added to the
mixture of the tin-containing metal oxide particles and the ionic
by-products, such as water, alcohols, amides, ketones, epoxides, or
mixtures thereof, to wash and further dissolve the ionic
by-products; the tin-containing metal oxide crystalline particles
settle to the bottom of the reaction mixture and can be separated
from the ionic by-products via centrifugation or any other physical
separation process (such as filtration). The ionic by-products
remain in the supernatant and are decanted after centrifugation.
The tin-containing metal oxide particles can be re-dispersed to
form monodispersion in the polar medium.
[0169] The resultant tin-containing metal oxide particles are
freely dissolved in a suitable solvent (62) to form a highly
concentrated monodispersion (65) that comprises the surfactant
coated tin-containing metal oxide crystalline particles. If an
organic solvent is used in the separating step (50), the resultant
tin-containing metal oxide particles are dissolved or dispersed
(60) in the organic phase medium. If a polar solvent is used in the
separating step (50), the resultant tin-containing metal oxide
particles are dissolved or dispersed (60) in the polar phase
medium. While the medium (62) used for dissolving or dispersing may
be the same as or different from the one used in the separating
step (20 or 50).
EXAMPLE
[0170] The present invention will be further described in greater
details by reference to specific examples, which should not be
considered as in any way limiting the scope of the invention.
Example 1
[0171] 350.8 g of tin tetrachloride pentahydrate dissolved in 1 L
of 2.5M diluted hydrochloric acid, and then 22.8 g of antimony
trichloride was added under vigorous stirring to a solution of tin
tetrachloride, maintaining the vigorous stirring to form a uniform
suspension.
[0172] During the vigorous stirring, 1 L of 6M aqueous ammonia was
added to the suspension, then keep at 60.degree. C. for 20 min. The
resulting pale yellow slurry was centrifuged and re-dispersed into
1.5 L of water, then centrifuged again, and repeated the above
procedure until nearly no ionic impurities.
[0173] The resulted filter cake was re-dispersed in around 1 L of
water, and transferred to a hydrothermal reactor with adding 100 ml
of hydrogen peroxide. The slurry was heated to 250.degree. C., and
held for 8 hours.
[0174] When the hydrothermal reactor was cooled to room
temperature, the dark blue slurry was centrifuged and washed by
water, then centrifuged to obtain a cake.
[0175] The cake was re-dispersed to about 600 mL of water, adding
7.5 g of triethanolamine, then add 300 mL of methanol solution
containing 22.5 g of cetyl trimethyl ammonium bromide and stirred
for about 10 min. The slurry was centrifuged, and dispersed into
1.5 L of water, centrifuged again, washed with water and acetone to
remove excess surfactants and ionic impurities. The cake obtained
by centrifugation was re-dispersed into 600 mL of acetone and
evaporated under reduced pressure until dryness without
acetone.
[0176] A further quantity of toluene, and 3 g octylamine were added
to finally form blue ATO dispersion in toluene with the solid
content of nano-particles (based on the weight of the dispersion)
at 40%.
[0177] FIG. 2 showed TEM results indicating that the initial
average particle diameter of the prepared ATO was between 5 to 7
nm, non-agglomerated among particles, nearly monodispersion. FIG. 3
showed a dynamic light scattering particle diameter analyzer test
results indicating that the secondary average particle diameter was
about 30 nm, D 90=53.1 nm. The resultant dispersion of the granules
was the index of dispersion degree of 5.4, steepness ratio of 2.5,
indicating that the particles have good dispersing properties in
dispersion.
Comparative Example 1
[0178] 350.8 g of tin tetrachloride pentahydrate was dissolved in 1
L of 2.5M diluted hydrochloric acid, then adding 22.8 g of antimony
trichloride with vigorous stiffing until forming a uniform
suspension.
[0179] During the vigorous stirring, 1 L of 6M aqueous ammonia was
added to the suspension and keep at 60.degree. C. for 20 min.
[0180] The resulted pale yellow pigment slurry was transferred to
the hydrothermal reactor, with adding 100 mL of hydrogen peroxide.
The slurry was heated to 250.degree. C. and maintained for 8
hours.
[0181] When hydrothermal reactor cooling down to room temperature,
the blue-gray slurry was collected and centrifuged to obtain a
cake.
[0182] The cake even after washing many times still cannot get a
dark blue cake similar to examples 1.
[0183] Additionally, this filter cake even washed and re-modified
in any case, can not be dispersed to form a monodispersed
dispersion.
[0184] After drying the cake analysed by XRD tests, showing that
despite cassiterite tetragonal structure (JCPDS21-1250) peaks
appeared, but there were many impurity peaks. Dynamic light
scattering particle diameter analyzer displayed that the average
secondary particle diameter was greater than 1 .mu.m, with wide and
bimodal particle diameter distribution.
[0185] This comparative example illustrates that tin-containing
metal oxide precursor particles (or tin-containing metal oxide
particles) separating in time with an ionic by-product is a very
key step to the preparation and the formation of monodispersed
dispersion of tin-containing metal oxide.
Example 2
[0186] Steps before the hydrothermal treatment and hydrothermal
treatment conditions and procedures were the same to described in
Example 1.
[0187] When hydrothermal reactor cooling down to room temperature,
blue slurry was collected and centrifuged, then washed and
dispersed in water, centrifuged again to obtain a cake.
[0188] The cake was re-dispersed to 1 L of methanol with 2.5 g of
tetramethyl ammonium hydroxide and 500 mL of methanol containing
44.5 g of Titanate coupling agent (product name: NDZ-311) and
stirred for 10 min. The slurry was centrifuged and sufficiently
dispersed into 1 L of methanol and centrifuged again. The sediment
was redispersed into 600 mL of butyl acetate, together with 7.5 g
of another titanate coupling agent (product name: NDZ-109). The
suspension was evaporated to dryness under reduced pressure to
collect the dark blue powder.
[0189] The powder was re-dispersed into the butyl acetate to the
solid content of ATO nano-particles (based on the weight of the
dispersion) at 40%.
[0190] The test results showed that the particle diameter and size
distribution of nano-ATO was similar to example 1. The resulting
dispersion of the particles have the index of dispersion degree of
5.5 and the steepness ratio of 2.6.
Example 3
[0191] 350.8 g of tin tetrachloride pentahydrate was dissolved in
1.5 L of methanol, then adding 22.8 g of antimony trichloride with
stirring to a clear solution.
[0192] During the stirring, 1 L of 6M aqueous ammonia was added to
the solution and maintained at 60.degree. C. for 30 min.
[0193] The resulted pale yellow slurry was centrifuged and
re-dispersed into 1.5 L of water, centrifuged again, repeated the
above procedure until nearly no ionic impurities.
[0194] The resulted cake was re-dispersed into 1 L of water and
transferred to hydrothermal reactor, with adding 100 mL of hydrogen
peroxide. The slurry was heated to 290.degree. C. and maintained
for 8 hours.
[0195] When hydrothermal reactor cooling down to room temperature,
the blue slurry was collected and centrifuged, then washed and
dispersed with water, and centrifuged to obtain a dark blue
cake.
[0196] The cake was re-dispersed into 600 mL of water, with 7.5 g
of tetramethyl ammonium hydroxide and 300 mL of methanol solution
containing 22.5 g of cetyl trimethyl ammonium bromide and stirred
for 10 min. The slurry was centrifuged and dispersed into 1.5 L of
water, centrifuged again, washed with water and acetone separately
to remove excess surfactants and ionic impurities, to obtain the
cake, which was re-dispersed into 600 mL of acetone. The suspension
was evaporated to dryness under reduced pressure to remove
acetone.
[0197] A certain quantity of toluene and 3 g octylamine were added
to finally form a blue toluene dispersion of ATO nano-particles
with the solid content (based on the weight of the dispersion) at
40%.
[0198] The particle diameter and XRD tests was performed. FIG. 4
showed TEM results indicating that the obtained initial average
particle diameter of the prepared individual ATO nanoparticles were
5 to 6 nm, no aggregation among particles, nearly monodispersion.
XRD results in FIG. 5 showed the tetragonal cassiterite structure
(JCPDS 21-1250) without impurity peak, indicating is doped antimony
oxide was not in the form of a separate oxide, but into the crystal
lattice of tin oxide. FIG. 6 of a dynamic light scattering particle
diameter analyzer test results showed that the average secondary
particle diameter of about 22 nm, D 90=48.1 nm. The resulted index
of dispersion degree in the dispersion was 3.5 and steepness ratio
1.9, indicating a narrow particle diameter distribution in
dispersions.
Example 4
[0199] Steps before the hydrothermal treatment and hydrothermal
treatment conditions and procedures were the same to described in
Example 3.
[0200] When hydrothermal reactor cooling down to room temperature,
blue slurry was collected and centrifuged, then washed and
dispersed by 1.5 L of water, centrifuged again to obtain a cake,
which was re-dispersed to 1.5 L of 30% aqueous ethanol and
centrifuged. The filter cake was dispersed in 70% aqueous ethanol
and centrifuged. The resulted cake was redispersed into 1 L of
ethanol and centrifuged to obtain a cake.
[0201] The last filter cake was dried at about 50.degree. C. and
pulverized to obtain ATO powder.
[0202] The amount of water was added to the dry powder, then 1%
weight of ATO of tetramethyl ammonium hydroxide was added, treated
by a homogenizer to disperse ATO uniformly in water, and finally to
form the water-based dispersion of ATO nano-particles with the
solids content (based on the weight of the dispersion) at 40%.
[0203] FIG. 7 showed TEM results indicating that uniform size of
ATO nano-particles with the initial average particle diameter of
the individual particles of about 8 to 10 nm. XRD results showed
that the structure of tetragonal cassiterite structure (JCPDS
21-1250). A dynamic light scattering particle diameter analyzer
showed that the average secondary particle diameter was about 50
nm. The resulted dispersion of the particles have the index of
dispersion degree of 4.2 and the steepness ratio of 2.2.
Example 5
[0204] Steps before the hydrothermal treatment and hydrothermal
treatment conditions and procedures were the same to described in
Example 3.
[0205] When hydrothermal reactor cooling down to room temperature,
blue slurry was collected and centrifuged, then washed and
dispersed by 1.5 L of water, centrifuged again. Dark blue filter
cake was re-dispersed in an aqueous methanol solution (methanol and
water by weight ratio of 9:1) to form 100 ml of suspension with
solid content at 30%, which was warmed to 60.about.70.degree. C.
Under stirring, 7 g of .gamma.-methacryloxypropyl trimethoxy silane
was added and maintained for 1 day. Then, the slurry was cooled to
room temperature, after adding 2 g of cetyl trimethyl ammonium
bromide, and stirred for 10 minutes.
[0206] The suspension was washed, centrifuged and separated to
obtain a cake.
[0207] The filter cake was dispersed by ethanol, then added 1 g of
octylamine. After rotary evaporation, butyl acetate was added to
obtain the dark blue nano-ATO dispersion in the dispersion medium
of butyl acetate with the solid content at 40%.
[0208] Particle diameter and size distribution of ATO
nano-particles is similar to Example 3. The resulted dispersion of
the particles have the index of dispersion degree of 5.2 and the
steepness ratio of 2.1.
Example 6
[0209] 35.08 g of tin tetrachloride pentahydrate was dissolved in
1.5 L of methanol with 293 g indium trichloride tetrahydrate under
stirring to a clear solution.
[0210] During stirring, 1 L of 6M aqueous ammonia was added to the
previous solution, and maintained for 30 min at 60.degree. C. The
resulted slurry was centrifuged and re-dispersed into 1.5 L of
water, centrifuged again, and repeated the above procedure until
nearly no ionic impurities.
[0211] The filter cake was re-dispersed in 1 L of water and
transferred to hydrothermal reactor, with adding 100 mL of
hydrazine hydrate. The slurry was heated to 290.degree. C. and
maintained for 8 hours.
[0212] When hydrothermal reactor cooling down to room temperature,
the blue slurry was collected and centrifuged, then washed and
dispersed with water, and centrifuged to obtain a cake.
[0213] The cake was re-dispersed into 600 mL of water, with 7.5 g
of tetramethyl ammonium hydroxide and 300 mL of methanol solution
containing 22.5 g of cetyl trimethyl ammonium bromide and stirred
for 10 min. The slurry was centrifuged and sufficiently dispersed
into 1.5 L of water, centrifuged again, washed with water and
acetone separately to remove excess surfactants and ionic
impurities, to obtain the cake, which was re-dispersed into 600 mL
of acetone. The suspension was evaporated to dryness under reduced
pressure to remove acetone.
[0214] A certain quantity of toluene and 3 g octylamine were added
to finally form a dark blue toluene dispersion of ITO
nano-particles with the solid content (based on the weight of the
dispersion) at 40%.
[0215] FIG. 8 showed TEM results that the initial average particle
diameter of individual ITO nanoparticles was about 7 nm. A dynamic
light scattering particle diameter analyzer showed that the average
secondary particle diameter was about 60 nm. The resultant
dispersion have index of dispersion degree of 6.4 and steepness
ratio of 2.7.
Example 7
[0216] 35.08 g of tin tetrachloride pentahydrate was dissolved in
1.5 L of water containing hydrochloric acid, then adding 293 g of
indium trichloride tetrahydrate under stirring to form a clear
solution.
[0217] During stirring, 1 L of 6M aqueous ammonia solution was
added to the solution with pH to about 7 and heated to 70.degree.
C., maintained for 30 min. The resulted slurry was centrifuged and
re-dispersed into 1.5 L of water, centrifuged again, repeated the
above procedure until nearly no ionic impurities.
[0218] The filter cake was re-dispersed into 1 L of ethanol and
transferred to a hydrothermal reactor, together with 4 g of citric
acid. The slurry was heated to 290.degree. C. and maintained for 8
hours.
[0219] When hydrothermal reactor cooling down to room temperature,
the blue slurry was collected and centrifuged, then washed and
dispersed with water, and centrifuged to obtain a cake.
[0220] The cake was re-dispersed into 600 mL of water, with 7.5 g
of tetramethyl ammonium hydroxide and 300 mL of methanol solution
containing 22.5 g of cetyl trimethyl ammonium bromide and stirred
for 10 min. The slurry was centrifuged and sufficiently dispersed
into 1.5 L of water, centrifuged again, washed with water and
acetone separately to remove excess surfactants and ionic
impurities, to obtain the cake, which was re-dispersed into 600 mL
of acetone. The suspension was evaporated to dryness under reduced
pressure to remove acetone.
[0221] A certain quantity of toluene and 3 g octylamine were added
to finally form a dark blue toluene dispersion of ITO
nano-particles with the solid content (based on the weight of the
dispersion) at 40%.
[0222] The properties of the prepared ITO nano-particles and their
dispersion were similar to example 6.
Example 8
[0223] This embodiment is application example.
[0224] In this example, the manufacturing method of ATO
nano-particles in a water-based dispersion is the same to in
Example 4, except that the hydrothermal temperature is 260.degree.
C., treatment time for 15 hours while the amount of antimony
(antimony relative to the ATO mole percent) of 5%, 7.5%, 10%,
12.5%. Prepared ATO nanoparticles was tested by TEM, XRD, dynamic
light scattering particle diameter analyzer showing that the
results are similar to example 4.
[0225] The obtained aqueous dispersion of ATO nano-particles in
various antimony concentrations with 40% of solids content were
diluted to 5% aqueous solution. UV-visible-IR spectroscopy showed
the change in the properties of IR blocking (seen in FIG. 9),
indicating that adjusting the concentration of antimony in ATO
nano-particles can cause changes in IR blocking performance in the
application system. Usually, the higher the antimony, the better
the IR blocking. when the content of antimony is more than 12%, the
IR blocking performance did not change much. This variation shows
that controlling the content of antimony in ATO nano-particles can
regulate the performance of IR blocking.
Example 9
[0226] This embodiment is application example.
[0227] In this example, the manufacturing method of ATO
nano-particles in a water-based dispersion is the same to in
Example 4, except that the hydrothermal temperature is 260.degree.
C., time for 15 hours. Prepared ATO nanoparticles was tested by
TEM, XRD, dynamic light scattering particle diameter analyzer
showing that the results are similar to example 4.
[0228] The obtained aqueous dispersion with 40% of solids content
of ATO nano-particles were diluted to 5%, 2.5%, 1.25% of solids
content of the aqueous solution, and found the change of IR
blocking performance by testing UV-visible-IR spectroscopy (see
FIG. 10). The higher the solids of the ATO nano-particles, the
better the IR blocking. This variation shows that controlling the
solids content of ATO nano-particles in the application system can
regulate the performance of IR blocking.
Example 10
[0229] This embodiment is application example.
[0230] In this example, the manufacturing method of ATO
nano-particles in a water-based dispersion is the same to in
Example 4, except that the hydrothermal temperature is 260.degree.
C., time for 15 hours. Prepared ATO nanoparticles was tested by
TEM, XRD, dynamic light scattering particle diameter analyzer
showing that the results are similar to example 4.
[0231] The obtained aqueous dispersion with 40% of solids content
of ATO nano-particles were diluted to 5% of solids content of the
aqueous solution, and prepared the composite metal oxide
dispersions by mixing with ZnO or CeO.sub.2 aqueous dispersion in
same solid content in preparation of PCT/SG2008/000442, separately.
UV-visible-IR spectroscopy testing found the dispersion had IR
blocking property similar to example 8, moreover, the addition of
ZnO or CeO2 showed significant UV blocking. The UV transmittance
testing results was shown in FIG. 11. This variation shows that
altering amount of UV blocking additives, such as ZnO or CeO.sub.2
to control the performance of UV blocking.
Example 11
[0232] The aqueous dispersion of nano ATO prepared as described in
example 4 in the present invention, alone or combination with nano
zinc oxide aqueous dispersion prepared in PCT/SG2008/000442,
was/were added to the aqueous acrylic acid coatings. In this
coating formulation, the acrylic resin comprised 20 wt % of the
total amount of the coating, which also contained a small amount of
levelling agents and other additives. ATO nanoparticles accounted
for 10 wt % of the total amount, ZnO nanoparticles 5 wt % of
that.
[0233] The coating was coated on the glass through the dip-coating
or the gravity-coating method, respectively. Controlling the
thickness of the coating on the glass was about 40 microns. In
accordance with China National Standard GB/T 2680-94 (or
international standard E 903-96), the glass coated with this
coating was analyzed by UV-visible-IR spectroscopy, as shown in
FIG. 12. FIG. 12 showed that ATO nano-particles in the coating
showed good IR blocking property, and ZnO nano-particles for UV
blocking function separately, without affecting the visible light
transmittance. The specific solar control properties were shown in
the following table.
TABLE-US-00001 TABLE 1 UV blocking Visible light Different types of
glass (350 nm) transmittance IR coating (%) (550 nm) (%) blocking
(%) ATO + ZnO, dip-coating 90% 80% 63% ATO + ZnO, gravity 95% 85%
65% coating ATO, dip-coating / 83% 73% ATO, gravity coating / 90%
70%
Comparative Example 2
[0234] To disperse commercially available ATO nano-powder with the
initial average particle diameter of 8-10 nm similar to the present
invention and the same amount of the same surfactant mentioned in
example 4 by conventional ball milling methods for 8 hours, ATO
dispersion was obtained with 123 nm of the average secondary
particle diameter analysed immediately by dynamic light scattering
particle diameter analyser. The resulted dispersion of the
particles had index of dispersion degree of 12.2 and the steepness
ratio of 4.1. (poor stability of the dispersion as settling at the
bottom of the container 2 days later. The dispersion was analysed
by a dynamic light scattering particle diameter analyzer again,
showing that the average secondary particle diameter increased to
253 nm and particle diameter distribution is further widened.)
[0235] The dispersion of nano-ATO by the ball milling for 8 hours
was rapidly adopted to water-based acrylic paint in the same
methods and amount as in example 10, which was applied on the glass
by gravity coating method, with coatings thickness to 40 microns.
In accordance with China National Standard GB/T 2680-94 (or
international standard E 903-96), the glass coated with the coating
was tested UV-visible-IR spectroscopy showing its specific solar
control performance in the following table.
TABLE-US-00002 TABLE 2 Visible light UV blocking transmittance
Different types of (350 nm) (550 nm) glass coating (%) (%) IR
blocking (%) ATO on commercial / 55% 73% market ATO prepared in /
90% 75% example 4
[0236] Judging from the appearance, the glass coated with
commercial ATO dispersion by ball milling looked blue and pale
without translucent character; while the glass coated with nano ATO
produced in Example 4 of the present invention had the light blue
transparent feature. The Comparative Example 2 shows that
dispersability of ATO nano-particles have an impact on the
transparency of coated glass. Only monodispersed particles in the
present invention can achieve high transparency and IR blocking
performance of the glass at the same time.
[0237] Applications
[0238] It will be appreciated that the disclosed process can enable
direct synthesis of tin-containing metal oxide nanoparticles or
tin-containing metal oxide nanoparticles in monodispersed state and
for further preparation of dispersion of metal oxide nanocomposites
for UV and IR blocking. The dispersion of tin-containing metal
oxide nanoparticles or dispersion of metal oxide nanocomposites for
UV and IR blocking may have a high concentration as defined by its
high solid loading.
[0239] Advantageously, all the reactants used in the disclosed
process are commercially available and economically priced. More
advantageously, the process does not require the use of high
temperature calcination. This lowers the cost of the production and
reduces the deterioration of the equipment used in the process.
There is no addition need for the use of expensive reactants for
the large scale production of the tin-containing metal oxide
nanoparticles, their dispersion and dispersion of metal oxide
nanocomposites for UV and IR blocking.
[0240] Advantageously, the monodispersion produced from the
disclosed process may be more stable as compared to known particles
from other methods, also with advantages that the particles do not
agglomerate, and the dispersion do not have ionic impurities. The
disclosed monodispersion can be kept for a period of more than one
month without any appreciable loss in stability properties. The
nano-sized tin-containing metal oxide particles can be re-dispersed
in a solvent to substantially reform into a monodispersion, without
any appreciable loss in physical stability.
[0241] Advantageously, the disclosed process enables a highly
concentrated dispersion of nano-sized tin-containing metal oxide,
or dispersion of metal oxide nanocomposites for UV and IR blocking.
This may significantly reduce the amount of storage space and the
cost of transportation as compared to known products of
tin-containing metal oxide nanoparticles and their dispersion.
[0242] Advantageously, the liquid-liquid phase transfer step may
provide a simple and effective solution to remove the by-products
that may be ionic in nature that cause destabilization of the
monodispersion.
[0243] It will be appreciated that the capacity of the process can
be scaled up to form larger quantities of tin-containing metal
oxide nanoparticles, their dispersion, and dispersion of metal
oxide nanocomposites for UV and IR blocking, without affecting the
stability and particle size distribution of the product.
[0244] Advantageously, the tin-containing metal oxide nanoparticles
may be re-dispersed in a suitable dispersing medium that may be
dependent on the needs of the user for the end-product.
Accordingly, a polar solvent or a non-polar solvent may be used as
the dispersing medium. The dispersion of tin-containing metal oxide
nanoparticles or dispersion of metal oxide nanocomposites for UV
and IR blocking may be suitable for use in an organic matrix
material, such as a polymeric material, according to the
requirements of the end-product, for application of glass paint or
shielding film. As using the tin-containing metal oxide
nanoparticles prepared with disclosed process, the secondary
particle size may be controlled in nano-scale, to result in highly
transparent glass coating or shielding film for both UV and IR
blocking without affect the visible light transmittance, and hence
to achieve good transparent effect and thermal insulation effect
for glass.
[0245] It will be apparent the various other modifications and
adaptations of the invention will be apparent to the person skilled
in the art after reading the foregoing disclosure without departing
from the spirit and scope of the invention and it is intended that
all such modifications and adaptations come within the scope of the
appended claims.
* * * * *