U.S. patent application number 10/419130 was filed with the patent office on 2003-11-13 for process for producing diantimony pentoxide sol.
This patent application is currently assigned to Nissan Chemical Industries, Ltd.. Invention is credited to Asada, Motoko, Koyama, Yoshinari, Suzuki, Keitaro.
Application Number | 20030211240 10/419130 |
Document ID | / |
Family ID | 29397341 |
Filed Date | 2003-11-13 |
United States Patent
Application |
20030211240 |
Kind Code |
A1 |
Suzuki, Keitaro ; et
al. |
November 13, 2003 |
PROCESS FOR PRODUCING DIANTIMONY PENTOXIDE SOL
Abstract
The present invention provides a process for producing a
diantimony pentoxide sol, characterized in that a diantimony
pentoxide sol having a particle size of 5 to 30 nm is used as a
nuclear sol and the sol is grown to an arbitrary particle size,
preferably a particle size of 40 to 300 nm. The process comprises
adding a hydrogen peroxide solution and diantimony trioxide into a
sol comprising diantimony pentoxide particles as a raw material,
and coating the diantimony pentoxide particles with a resulting
antimony compound, preferably diantimony pentoxide. In the process,
the coating is preferably carried out in such a manner that a
particle size of particles in a sol as a raw material increases by
a factor of 1.3 to 60.
Inventors: |
Suzuki, Keitaro;
(Sodegaura-shi, JP) ; Koyama, Yoshinari;
(Sodegaura-shi, JP) ; Asada, Motoko;
(Sodegaura-shi, JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 19928
ALEXANDRIA
VA
22320
US
|
Assignee: |
Nissan Chemical Industries,
Ltd.
Tokyo
JP
|
Family ID: |
29397341 |
Appl. No.: |
10/419130 |
Filed: |
April 21, 2003 |
Current U.S.
Class: |
427/212 |
Current CPC
Class: |
C01P 2006/80 20130101;
C01P 2004/62 20130101; C01P 2006/22 20130101; C08J 9/00 20130101;
B82Y 30/00 20130101; C01P 2004/64 20130101; C01P 2004/84 20130101;
C01P 2006/12 20130101; C01G 30/005 20130101 |
Class at
Publication: |
427/212 |
International
Class: |
C08J 009/00; B05D
007/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 7, 2002 |
JP |
2002-131291 |
Claims
What is claimed is:
1. A process for producing a sol comprising diantimony pentoxide
particles coated with an antimony compound, in which the process
comprises adding a hydrogen peroxide solution and diantimony
trioxide into a sol comprising diantimony pentoxide particles as a
raw material, and coating the diantimony pentoxide particles with a
resulting antimony compound.
2. The process according to claim 1, wherein the antimony compound
which is coated on the diantimony pentoxide particles is diantimony
pentoxide.
3. The process according to claim 1 or 2, wherein the coating is
carried out in such a manner that a particle size of particles in a
sol as a raw material increases by a factor of 1.3 to 60.
4. The process according to any one of claims 1 to 3, wherein the
sol as a raw material is a sol comprising diantimony pentoxide
particles having a particle size of 5 to 30 nm.
5. The process according to any one of claims 1 to 4, wherein the
sol obtained by coating is a sol comprising diantimony pentoxide
particles having a particle size of 40 to 300 nm.
6. The process according to any one of claims 1 to 5, wherein the
coating with an antimony compound is carried out by adding a
hydrogen peroxide solution and diantimony trioxide in
H.sub.2O.sub.2/Sb.sub.2O.sub.3 molar ratio of 2 to 2.5 into a
diantimony pentoxide sol as a raw material, and then heating.
7. The process according to any one of claims 1 to 6, wherein the
addition of the hydrogen peroxide solution and diantimony trioxide
is carried out by any one of the following method i), ii) or iii):
method i): the hydrogen peroxide solution and diantimony trioxide
are added alternately into the diantimony pentoxide sol; method
ii): the hydrogen peroxide solution is first added into the
diantimony pentoxide sol, and then diantimony trioxide is added
thereinto; or method iii): a mixed slurry of the hydrogen peroxide
solution and diantimony trioxide is added into the diantimony
pentoxide sol.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Art
[0002] The present invention relates to a process for producing a
diantimony pentoxide sol, characterized in that a diantimony
pentoxide sol having a particle size of 5 to 30 nm is used as a
nuclear sol and the sol is grown to an arbitrary particle size,
preferably a particle size of 40 to 300 nm.
[0003] 2. Description of the Related Art
[0004] Diantimony pentoxide sols are used as fire retardant
auxiliaries for plastics, fibers and the like, microfillers for
surface treatment of glass or plastics, inorganic ion exchangers,
and so on. Generally, sols having a high concentration (30 to 50%
in terms of Sb.sub.2O.sub.5) stabilized with an organic base are
used for the above-mentioned purpose.
[0005] Conventionally, it is known that diantimony pentoxide sols
are prepared according to the following methods.
[0006] The methods reported hitherto include a method in which an
alkali antimonate is deionized with a cation exchange resin
(Japanese Patent Publication No. 52-21298, U.S. Pat. No. 4,110,247
or Japanese Patent Publication No. 57-11848), and a method in which
diantimony trioxide is oxidized with hydrogen peroxide solution at
high temperatures (Japanese Patent Publication No. 53-20479, and
Japanese Patent Laid-open Nos. 52-21298, 52-131998, 52-123997,
60-137828 and 2-180717).
[0007] As methods other than the above-mentioned ones, are known a
method in which an alkali antimonate is reacted with an inorganic
acid, and then a peptization is carried out (Japanese Patent
Laid-open Nos. 60-41536 and 61-227918) and the like.
[0008] In addition, Japanese Patent Laid-open No 2-107523 reports a
process for producing Sb.sub.2O.sub.5 sol having a particle size of
40 to 300 nm and a particle shape of regular octahedron, in which
an alkali antimonate is reacted with a mono- or divalent inorganic
acid in a stoichiometric ratio of 1:0.7 to 5 to give a diantimony
pentoxide gel, the gel is separated and washed with water to give a
wet cake, and the wet cake is added and peptized intermittently or
continuously into a diantimony pentoxide sol.
[0009] The prior processes for producing diantimony pentoxide sol
as mentioned above have the following disadvantages.
[0010] The ion exchange method has characteristics that the
resulting diantimony pentoxide sol is excellent in dispersion
properties and can be mixed into a medium in a high concentration
because the sol is nearly spherical. However, it is difficult to
perform an ion exchange in a diantimony pentoxide concentration of
10% and more in this method. Further, this method has disadvantages
that it includes tedious processes for separating and regenerating
ion exchange resins.
[0011] Further, the oxidation method affords directly a sol
comprising diantimony pentoxide in a high concentration as much as
about 30%, but the sol has a high viscosity, and has low dispersion
properties as the colloidal particles have irregular shapes, and
further has a bad compatibility with resin emulsion or the like as
the sol has a high surface activity. As a method in order to
improve the stability of diantimony pentoxide sol obtained by the
oxidation method, it is proposed to add an acid comprising
pentavalent phosphorus or arsenic in an amount of 0.01 mole or
above on the basis of 1 mole of Sb when a diantimony pentoxide sol
is produced (Offenlegungsschrift No. P 2931523). However, the
polymerization of antimonic acids is markedly depressed due to
phosphoric acid or arsenic acid and thus polyantimonate ion or fine
colloidal diantimony pentoxide particles with a particle size of 5
nm or less is produced. Therefore, the resulting sol has
disadvantages that it has very high viscosity and rises remarkably
in viscosity upon storage.
SUMMARY OF THE INVENTION
[0012] An object of the present invention is to provide a process
for preparing industrially a sol comprising diantimony pentoxide
with large particle size, which eliminates the above-mentioned
disadvantages in the prior processes for preparing diantimony
pentoxide sol.
[0013] In order to achieve the object, the present invention as a
first aspect provides a process for producing a sol comprising
diantimony pentoxide particles coated with an antimony compound,
characterized in that the process comprises adding a hydrogen
peroxide solution and diantimony trioxide into a sol comprising
diantimony pentoxide particles as a raw material to give antimony
compound in the sol, and coating the diantimony pentoxide particles
with the resulting antimony compound.
[0014] A second aspect of the present invention is the process as
set forth in the first aspect, wherein the antimony compound which
is coated on the diantimony pentoxide particles is diantimony
pentoxide.
[0015] A third aspect of the present invention is the process as
set forth in the first or second aspect, wherein the coating is
carried out in such a manner that a particle size of particles in a
sol as a raw material increases by a factor of 1.3 to 60.
[0016] A fourth aspect of the present invention is the process as
set forth in any one of the first to third aspects, wherein the sol
as a raw material is a sol comprising diantimony pentoxide
particles having a particle size of 5 to 30 nm.
[0017] A fifth aspect of the present invention is the process as
set forth in any one of the first to fourth aspects, wherein the
sol obtained by coating is a sol comprising diantimony pentoxide
particles having a particle size of 40 to 300 nm.
[0018] A sixth aspect of the present invention is the process as
set forth in any one of the first to fifth aspects, wherein the
coating with an antimony compound is carried out by adding a
hydrogen peroxide solution and diantimony trioxide in
H.sub.2O.sub.2/Sb.sub.2O.sub.3 molar ratio of 2 to 2.5 into a
diantimony pentoxide sol as a raw material, and then heating.
[0019] A seventh aspect of the present invention is the process as
set forth in any one of the first to sixth aspects, wherein the
addition of the hydrogen peroxide solution and diantimony trioxide
is carried out by any one of the following method i), ii) or
iii):
[0020] method i): the hydrogen peroxide solution and diantimony
trioxide are added alternately into the diantimony pentoxide
sol;
[0021] method ii): the hydrogen peroxide solution is first added
into the diantimony pentoxide sol, and then diantimony trioxide is
added thereinto; or
[0022] method iii): a mixed slurry of the hydrogen peroxide
solution and diantimony trioxide is added into the diantimony
pentoxide sol.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] As mentioned above, the present invention relates to a
process for producing a sol comprising diantimony pentoxide
particles coated with an antimony compound, characterized in that
the process comprises adding a hydrogen peroxide solution and
diantimony trioxide into a sol comprising diantimony pentoxide
particles as a raw material, and coating the diantimony pentoxide
particles with a resulting antimony compound.
[0024] The antimony compound which are coated on the diantimony
pentoxide particles is one obtained by the reaction of diantimony
trioxide with hydrogen peroxide. The antimony compound is
diantimony pentoxide or antimony oxides comprising diantimony
pentoxide as a main component.
[0025] In the process, the coating is carried out in such a manner
that a particle size of particles in a sol as a raw material grows
and increases by a factor of 1.3 to 60.
[0026] More specifically, the present invention relates to a
process for producing a sol comprising enlarged diantimony
pentoxide particles, in which the process comprises adding a
hydrogen peroxide solution and diantimony trioxide into a sol
comprising diantimony pentoxide particles as a raw material, and
coating the diantimony pentoxide particles with a resulting
diantimony pentoxide in such a manner that a particle size of the
particles increases by a factor of 1.3 to 60.
[0027] The particle size of the diantimony pentoxide particles in
the diantimony pentoxide sol used as raw material is not limited.
Generally, a sol comprising diantimony pentoxide particles having a
particle size of 5 to 30 nm is used, and a sol comprising particles
grown and having a particle size of 40 to 300 nm is obtained.
[0028] The present invention includes a process for enlarging
further a particle size of diantimony pentoxide particles, in which
a sol comprising diantimony pentoxide of which the particle size is
enlarged by the process of the present invention is used as raw
material.
[0029] The characteristics of the present invention resides mainly
in the enlargement of particle in a sol (raw material sol)
containing diantimony pentoxide particles having a particle size of
5 to 30 nm by coating the surface of the particle in raw material
sol with diantimony pentoxide in such a manner that a particle size
of the particle becomes 40 to 300 nm.
[0030] The methods for coating with antimony compounds,
particularly diantimony pentoxide include, for example a production
of an antimonic acid or fine colloidal diantimony pentoxide by the
reaction of hydrogen peroxide with diantimony trioxide, and
heating.
[0031] The particle size of diantimony pentoxide sol particles used
as raw material sol in the present invention is, for example a
primary particle size of 5 to 100 nm, and preferably 5 to 30 nm. As
the diantimony pentoxide sols, ones prepared by known methods can
be used. Particles in these sols act as nuclear particles. The
diantimony pentoxide sols may be acidic, neutral or basic, and are
preferably acidic.
[0032] The methods for preparing the above-mentioned diantimony
pentoxide sols include, for example a method comprising deionizing
an alkali antimonate (Japanese Patent Publication No. 57-11848 and
U.S. Pat. No. 4,110,247), a method comprising oxidizing diantimony
trioxide with hydrogen peroxide at high temperatures (Japanese
Patent Publication Nos. 53-20479 and 52-21298, and Japanese Patent
Laid-open Nos. 60-137828 and 2-180717) or a method comprising
peptizing with an amine a diantimony pentoxide gel obtained by
reacting sodium antimonate with an acid, which the present
inventors developed (Japanese Patent Laid-open No. 60-41536).
[0033] The method comprising preparing and heating antimonic acid
or fine colloidal diantimony pentoxide prepared by the reaction of
hydrogen peroxide with diantimony trioxide, comprises adding a
hydrogen peroxide solution and diantimony trioxide into a
diantimony pentoxide sol as a raw material and heating the
resulting mixture.
[0034] As the above-mentioned diantimony trioxide, one having a
mean particle size of 100 .mu.m or less is used, and particularly
one having the particle size of 10 .mu.m or less is preferable from
the viewpoint of dispersibility, reactivity with hydrogen peroxide
solution and so on.
[0035] In the coating, a hydrogen peroxide solution and diantimony
trioxide are generally used in H.sub.2O.sub.2/Sb.sub.2O.sub.3 molar
ratio of 2.0 to 2.5, and preferably 2.0. The conversion of
diantimony trioxide into diantimony pentoxide is insufficient when
the molar ratio is less than 2.0, while the conversion is
sufficient but H.sub.2O.sub.2 is in excess thereby causing
economical problems when the molar ration is more than 2.0.
[0036] The reaction is carried out at a temperature of 30 to
200.degree. C., preferably 80 to 100.degree. C.
[0037] Diantimony pentoxide for forming the coating layer of the
present invention is preferably added in terms of diantimony
trioxide added in such a manner that the molar ration of
(Sb.sub.2O.sub.3 added)/(Sb.sub.2O.sub.5 in diantimony pentoxide
sol as a raw material) is 1 and more. Although the molar ratio of
less than 1 can be used, the effect on the growth of particles (the
enlargement of the particle size of particles in diantimony
pentoxide sol as raw material) is low.
[0038] The addition of the hydrogen peroxide solution and
diantimony trioxide can be carried out continuously or
intermittently. In addition, a mixed slurry of the hydrogen
peroxide'solution and diantimony trioxide can be added into the
diantimony pentoxide sol or diantimony trioxide can be added after
hydrogen peroxide is added previously into the diantimony pentoxide
sol. Further, the hydrogen peroxide solution and diantimony
trioxide can be added alternately into the diantimony pentoxide
sol. In this case, the order of the addition of diantimony trioxide
and hydrogen peroxide solution is not specifically limited. In the
above-mentioned methods, it is preferable to add finally diantimony
trioxide and hydrogen peroxide solution in
H.sub.2O.sub.2/Sb.sub.2O.sub.3 molar ratio of 2.0.
[0039] As the reaction by the addition of diantimony trioxide and
hydrogen peroxide solution is an oxidative exothermic reaction, it
is preferable to perform the reaction with cooling of the reactor
or under reflux. When diantimony trioxide and hydrogen peroxide
solution are added intermittently, the addition is carried out at
10- to 20-minute intervals alternately. The amount to be added for
once is suitably in a molar ratio (Sb.sub.2O.sub.3
added)/(Sb.sub.2O.sub.5 in diantimony pentoxide sol as raw
material) of about 0.1 to 1.0. Although there is no problem that
the molar ratio is less than 0.1, the number of addition becomes
larger, and therefore the reaction is time-consuming and is not
efficient. In addition, there is no problem that the molar ratio is
more than 1.0, the amount added for once becomes larger, a
calorific value becomes higher, and it becomes difficult to control
the temperature. Further, in the latter case, independent small
particles are newly produced, and thereby the particle growth
becomes uneven and particle size is widely distributed. Thus, it is
not preferable when particles with sharp particle size distribution
should be produced.
[0040] It is assumed that diantimony trioxide added in the present
invention is subject to an oxidative reaction with hydrogen
peroxide in the system to give fine diantimony pentoxide colloidal
particles, and that the colloidal particles are bonded on the
surface of colloidal particles of diantimony pentoxide sol (acting
as a nuclear particle) present in the system and thereby the
particle growth takes place. The higher the ratio of diantimony
trioxide to diantimony pentoxide previously introduced as a nuclear
particle is, the larger the particle size of the resulting sol
becomes.
[0041] The diantimony pentoxide sol produced by the present
invention has a pH of 2 to 4. The pH can be controlled to a value
of 4 to 11 with an addition of an inorganic base, such as lithium
hydroxide, sodium hydroxide, potassium hydroxide or ammonia,
alkanolamines, such as triethanolamine or monoethanolamine,
alkylamines, such as triethylamine or n-propylamine, an organic
base, such as quaternary ammonium hydroxide or guanidine
hydroxide.
[0042] When the concentration of the resulting sol should be high,
it can be concentrated by a general method, such as evaporation
method or ultrafiltration method. In order to improve further the
stability of the sol, it is preferable to be concentrated after
controlling the pH of the sol to a value of 5 to 8 with the
above-mentioned bases, in particular organic bases.
[0043] According to the process for producing diantimony pentoxide
sols of the present invention, the particle size of particles in a
diantimony pentoxide sol can be arbitrarily controlled and the
particles have a sharp particle size distribution. Therefore, the
sols prepared by the present invention are excellent in dispersion
properties, and useful for fire retardant auxiliaries for plastics,
fibers and the like, microfillers for surface treatment of glass or
plastics, inorganic ion exchangers, and so on.
EXAMPLES cl Reference Example 1
[0044] This example shows preparation of a diantimony pentoxide sol
used as a raw material for preparing a sol of the present
invention.
[0045] When 203.8 g of diantimony trioxide (produced by Guangdong
Mikuni Antimony Industries Co., Ltd.; amount of Sb.sub.2O.sub.3:
99.5 wt %) and 270.5 g of 35 wt % hydrogen peroxide solution were
added into 2225.6 g of pure water and heated at 80.degree. C., the
reaction was started and the temperature of the mixed solution rose
to 95 to 100.degree. C. due to reaction heats. Then, 203.8 g of
diantimony trioxide was further added thereto, maturation was
carried out at a temperature of 90 to 95.degree. C. for 2 hours to
complete the reaction, and 2903.7 g of the intended diantimony
pentoxide sol was obtained. The obtained sol had a specific gravity
of 1.152, a viscosity of 2.6 c.p., a pH of 3.50 and Sb.sub.2O.sub.5
amount of 15.5 wt %. In addition, the observation with an electron
microscope showed that particles in the sol had a primary particle
size of 15 to 20 nm.
Reference Example 2
[0046] This example shows preparation of another diantimony
pentoxide sol used as a raw material for preparing a sol of the
present invention.
[0047] 800 g of sodium antimonate (64 wt % of Sb.sub.2O.sub.3 and
12.27 wt % of Na.sub.2O was contained) was added into 1532 g of
water to give a slurry. Then, 396 g of 35% hydrochloric acid was
added into the slurry and warmed at 27.degree. C. And, the reaction
was carried out at the temperature for 3 hours. Subsequently, the
resulting slurry of diantimony pentoxide was filtered with suction,
and washed with 3200 g of water. 755 g of the resulting diantimony
pentoxide gel wet cake was dispersed in 1952.7 g of water, and
then, after 9.1 g of 85% orthophosphoric acid was added, the
temperature was elevated to 85.degree. C. and peptization was
carried out at the temperature for 2 hours, and 2716.8 g of the
intended diantimony pentoxide sol was obtained. The obtained sol
had a specific gravity of 1.202, a pH of 2.12, a viscosity of 6.4
c.p. and Sb.sub.2O.sub.5 amount of 17.8 wt %. In addition, the
observation with an electron microscope showed that particles in
the sol had a primary particle size of 10 to 20 nm.
Example 1
[0048] After 1451.6 g of the diantimony pentoxide sol prepared in
Reference Example 1 was warmed to 75.degree. C., 81.0 g of
diantimony trioxide (produced by Guangdong Mikuni Antimony
Industries Co., Ltd.; amount of Sb.sub.2O.sub.3: 99.5 wt %) and
53.8 g of 35 wt % hydrogen peroxide solution were added thereto at
10- to 15-minute intervals 8 times in total alternately and
intermittently to allow to react. In the course of the reaction,
the temperature of the reacting liquid was kept at 90 to 99.degree.
C. while cooling. The total amount of diantimony pentoxide for
forming a coating layer was such an amount as the molar ration of
(Sb.sub.2O.sub.3 added)/(Sb.sub.2O.sub.5 in diantimony pentoxide
sol as raw material) was 3.18 in case where the total amount was
calculated to the amount of diantimony trioxide added. In addition,
the amount of diantimony trioxide and hydrogen peroxide solution
added for forming the coating layer corresponded to 2.0 in
H.sub.2O.sub.2/Sb.sub.2O.sub.3 molar ratio.
[0049] To the resulting sol, 47.0 g of triethanolamine was added,
and concentrated by an evaporation method to give 1898.5 g of the
intended diantimony pentoxide sol. The obtained sol had a specific
gravity of 1.766, a pH of 4.70, a viscosity of 7.4 c.p. and
Sb.sub.2O.sub.5 amount of 49.5 wt %. As to particle size, the
observation with an electron microscope showed that particles in
the sol had a primary particle size of 40 to 50 nm.
Example 2
[0050] 300 g of the diantimony pentoxide sol prepared in Reference
Example 1, 1910.8 g of water and 270.7 g of 35 wt % hydrogen
peroxide solution were charged in a reactor, heated at 90.degree.
C., and 40.8 g of diantimony trioxide (produced by Guangdong Mikuni
Antimony Industries Co., Ltd.; amount of Sb.sub.2O.sub.3: 99.5 wt
%) was added thereto under reflux at 15- to 20-minute intervals 10
times in total intermittently to allow to react. The total amount
of diantimony pentoxide for forming a coating layer was such an
amount as the molar ration of (Sb.sub.2O.sub.3
added)/(Sb.sub.2O.sub.5 in diantimony pentoxide sol as raw
material) was 9.69 in case where the total amount was calculated to
the amount of diantimony trioxide added. In addition, the amount of
diantimony trioxide and hydrogen peroxide solution added for
forming the coating layer corresponded to 2.0 in
H.sub.2O.sub.2/Sb.sub.2O.sub.3 molar ratio.
[0051] Thus, 2876 g of diantimony pentoxide sol was obtained. The
sol had a specific gravity of 1.168, a pH of 2.35, a viscosity of
1.1 c.p. and Sb.sub.2O.sub.5 amount of 17.2 wt %. As to particle
size, the observation with an electron microscope showed that
particles in the sol had a primary particle size of 150 to 200
nm.
Example 3
[0052] 2584.3 g of water was weighed out in a reactor, and 40.8 g
of diantimony trioxide (produced by Guangdong Mikuni Antimony
Industries Co., Ltd.; amount of Sb.sub.2O.sub.3: 99.5 wt %) and
270.7 g of 35 wt % hydrogen peroxide were added thereto with
stirring, and heated at 90.degree. C. to allow to react, and
thereby a sol containing particles as a raw material was prepared.
The sol had a primary particle size of 15 to 20 nm as a result of
observation with an electron microscope.
[0053] Thereafter, 40.8 g of diantimony trioxide was added thereto
at 10-minute intervals 9 times in total intermittently to allow to
react. The total amount of diantimony pentoxide for forming a
coating layer was such an amount as the molar ration of
(Sb.sub.2O.sub.3 added)/(Sb.sub.2O.sub.5 in diantimony pentoxide
sol as raw material) was 10.0 in case where the total amount was
calculated to the amount of diantimony trioxide added. In addition,
the amount of diantimony trioxide and hydrogen peroxide solution
added for forming the coating layer corresponded to 2.0 in
H.sub.2O.sub.2/Sb.sub.2O.sub.3 molar ratio.
[0054] Thus, 2895 g of diantimony pentoxide sol was obtained. The
sol had a specific gravity of 1.144, a pH of 2.30, a viscosity of
1.5 c.p. and Sb.sub.2O.sub.5 amount of 15.0 wt %. As to particle
size, the observation with an electron microscope showed that
particles in the sol had a primary particle size of 40 to 50
nm.
Example 4
[0055] 108.6 g of the diantimony pentoxide sol prepared in
Reference Example 2 and 809.8 g of water were charged in a reactor
and heated to 90.degree. C. Then, 17.5 g of diantimony trioxide
(produced by Guangdong Mikuni Antimony Industries Co., Ltd.; amount
of Sb.sub.2O.sub.3: 99.5 wt %) and 11.7 g of 35 wt % hydrogen
peroxide solution were added thereto at 15-minute intervals 8 times
in total alternately and intermittently to allow to react. The
total amount of diantimony pentoxide added for forming a coating
layer was such an amount as the molar ration of (Sb.sub.2O.sub.3
added)/(Sb.sub.2O.sub.5 in diantimony pentoxide sol as raw
material) was 8.0 in case where the total amount was calculated to
the amount of diantimony trioxide added. In addition, the amount of
diantimony trioxide and hydrogen peroxide solution added for
forming the coating layer corresponded to 2.0 in
H.sub.2O.sub.2/Sb.sub.2O.sub.3 molar ratio.
[0056] Thus, 1151 g of diantimony pentoxide sol was obtained. The
obtained sol had a specific gravity of 1.144, a pH of 2.54, a
viscosity of 1.4 c.p. and Sb.sub.2O.sub.5 amount of 15.1 wt %. As
to particle size, the observation with an electron microscope
showed that particles in the sol had a primary particle size of 40
to 50 nm.
Example 5
[0057] 518.4 g of water, 4.5 g of diantimony trioxide (produced by
Guangdong Mikuni Antimony Industries Co., Ltd.; amount of
Sb.sub.2O.sub.3: 99.5 wt %) and 240.3 g of 35 wt % hydrogen
peroxide solution were charged in a reactor, heated at 90.degree.
C. to allow to react and thereby a diantimony pentoxide sol as a
raw material was prepared. The sol had a primary particle size of
10 to 15 nm as a result of observation with an electron microscope.
Then, a slurry in which 357.7 g of diantimony trioxide was
dispersed into 459.9 g of water was added to the reactor with a
metering pump under reflux continuously over about 2 hours to allow
to react. The total amount of diantimony pentoxide for forming a
coating layer was such an amount as the molar ration of
(Sb.sub.2O.sub.3 added)/(Sb.sub.2O.sub.5 in diantimony pentoxide
sol as raw material) was 79.5 in case where the total amount was
calculated to the amount of diantimony trioxide added. In addition,
the amount of diantimony trioxide and hydrogen peroxide solution
added for forming the coating layer corresponded to 2.0 in
H.sub.2O.sub.2/Sb.sub.2O.sub.3 molar ratio.
[0058] Thus, 1538.9 g of diantimony pentoxide sol was obtained. The
sol had a specific gravity of 1.244, a pH of 2.30, a viscosity of
1.5 mPa.multidot.s and Sb.sub.2O.sub.5 amount of 25.3 wt %. As to
particle size, the observation with an electron microscope showed
that particles in the sol had a primary particle size of 80 to 90
nm.
Example 6
[0059] Into a reactor, 243.2 g of water, 12.5 g of diantimony
pentoxide sol prepared in Example 5 as a raw material sol and 156.3
g of 35 wt % hydrogen peroxide solution were charged, and heated
under reflux. Then, a slurry in which 235.5 g of diantimony
trioxide (produced by Guangdong Mikuni Antimony Industries Co.,
Ltd.; amount of Sb.sub.2O.sub.3: 99.5 wt %) was dispersed into
353.2 g of water was added to the reactor with a metering pump
continuously over about 2 hours to allow to react. The total amount
of diantimony pentoxide for forming a coating layer was such an
amount as the molar ration of (Sb.sub.2O.sub.3
added)/(Sb.sub.2O.sub.5 in diantimony pentoxide sol as raw
material) was 82.3 in case where the total amount was calculated to
the amount of diantimony trioxide added. In addition, the amount of
diantimony trioxide and hydrogen peroxide solution added for
forming the coating layer corresponded to 2.0 in
H.sub.2O.sub.2/Sb.sub.2O.sub.3 molar ratio.
[0060] Thus, 1000.7 g of diantimony pentoxide sol was obtained. The
sol had a specific gravity of 1.264, a pH of 2.20, a viscosity of
2.5 c.p. and Sb.sub.2O.sub.5 amount of 26.3 wt %. As to particle
size, the observation with an electron microscope showed that
particles in the sol had a primary particle size of 180 to 200
nm.
* * * * *