Process for producing diantimony pentoxide sol

Details Process for producing diantimony pentoxide sol Process for producing diantimony pentoxide sol

2003-04-21

2003-11-11

Foelak, Morton (Department: 1711)

Colloid systems and wetting agents; subcombinations thereof; pro

Continuous liquid or supercritical phase: colloid systems;...

Primarily organic continuous liquid phase

C106S286200, C427S215000, C428S689000

Reexamination Certificate

active

06646015

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Art
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.
2. Description of the Related Art
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
2
O
5
) stabilized with an organic base are used for the above-mentioned purpose.
Conventionally, it is known that diantimony pentoxide sols are prepared according to the following methods.
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).
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.
In addition, Japanese Patent Laid-open No 2-107523 reports a process for producing Sb
2
O
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.
The prior processes for producing diantimony pentoxide sol as mentioned above have the following disadvantages.
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.
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
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.
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.
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.
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.
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.
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.
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
2
O
2
/Sb
2
O
3
molar ratio of 2 to 2.5 into a diantimony pentoxide sol as a raw material, and then heating.
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):
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 OF THE PREFERRED EMBODIMENTS
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.
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.
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.
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.
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.
The present invention includes a process for enlarging further

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