JPS6345123A - Fine powder titanium dioxide composition - Google Patents

Abstract

PURPOSE:To produce the titled composition capable of imparting transparency and ultraviolet-shielding capability when compounded to a film or molded article, etc., of a resin, by applying a specific amount of silicon and/or aluminum oxide to the surface of titanium dioxide fine particles having a specific diameter. CONSTITUTION:The objective fine powder titanium dioxide composition can be produced by applying silicon and/or aluminum oxide to the surface of titanium dioxide particles wherein particles having diameter of 0.01-0.1mu account for >=80% of the whole particles. The amount of the Si and/or Al oxide is 1-20wt% in terms of SiO2 or Al2O3 based on TiO2. The composition is produced e.g. by hydrolyzing an acidic aqueous solution of titanium under heating, washing and deflocculating the precipitated coagulum, calcining the non- coagulated metatitanic acid, dispersing the obtained titanium dioxide in water, precipitating a specific amount of hydrated oxide of silicon and/or aluminum to the surface of the titanium dioxide particle and crushing the product after drying.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a finely powdered titanium dioxide composition in which silicon and/or aluminum oxides are present on the particle surface.

It is already known that fine titanium dioxide powder, most of which has a particle size of 0.1μ or less, exhibits different properties from pigment-rimmed titanium dioxide, which typically has a particle size of 0.15 to 0.5μ. . For example, when this material is blended into a resin film or molded product, it transmits visible light and does not affect the hue of other pigments or dyes, but it blocks ultraviolet rays and causes discoloration and discoloration due to ultraviolet rays.
Protecting materials that are subject to deterioration.

However, such fine titanium dioxide powder
It is not easy to manufacture, and there are problems with the dispersibility when mixed with the dispersion medium resin and the property of oxidizing and deteriorating the dispersion medium resin in the product, so it is difficult to develop an improved product that can be easily and stably manufactured industrially. desired.

The present invention relates to a novel titanium dioxide composition in which the surface of fine titanium dioxide particles having a size substantially within the range of 0.01 to 0.1 μm is treated with an oxide of silicon and/or aluminum.

The composition of the present invention has the oxide dispersed and contained in the resin, compared to a composition in which the oxide is not present on the particle surface. In addition to being superior in terms of transparency and UV shielding properties, it also has better dispersibility than -N5, and does not cause deterioration of the dispersion medium resin.
There aren't many things.

That is, the present invention provides finely powdered titanium dioxide in which oxides of silicon and/or aluminum are present on the particle surface, and 80% or more of the titanium dioxide particles are 0.
The size is within the range of 0.01 to 0.1μ, and the amounts of silicon and aluminum oxides are 5ifh and A1, respectively.
□0. 1 to 20ffi amount% (TiOz base m)
This is a finely powdered titanium dioxide composition characterized by providing transparency and ultraviolet shielding properties when incorporated into a resin film or molded product.

-i, the crystal form of titanium dioxide is roughly divided into rutile type and anatase type, but in the composition of the present invention, it may be either rutile type, anatase type, or a mixture of both types.
The particle size of titanium dioxide is such that more than 80% of the particles are 0.0
It is in the form of a fine powder with a size in the range of 1 to 0.1 micron, more preferably 0.01 to 0.05 micron.

In order to improve the transparency to visible light, the particle size can be made small, but if the particle size is made too small, the surface activity of titanium dioxide becomes strong and ultraviolet rays are also transmitted, which is not preferable. On the other hand, ultraviolet shielding properties depend on the ability to absorb and scatter ultraviolet light, but if the particle size is increased to increase the light scattering ability, the light scattering ability for visible light will also increase, impairing transparency. . Titanium dioxide having the above particle size range has sufficient transparency and ultraviolet shielding properties when dispersed in a resin or the like.

As mentioned above, the composition of the present invention has a specific oxide present on the surface of titanium dioxide particles, and it is preferable that these oxides be coated with a continuous film, but it may not be coated with a discontinuous film. This specific oxide surface treatment, which may be present or may be attached to the surface, may be silicon or aluminum oxide alone, or silicon and aluminum oxide. In the case of this surface treatment of silicon and aluminum oxides, it is preferable to treat the silicon oxide first and then the aluminum oxide, but it is better to treat a mixture of silicon and aluminum oxides, such as aluminum silicate. Furthermore, in addition to silicon and aluminum oxides, for example, titanium oxide, zinc oxide, etc. may also be present on the particle surface.

Since the oxide present on the surface of the titanium dioxide particles is a dried hydrated oxide, the amount of silicon and aluminum oxides is 5 iOz each, including cases where part or all of the oxide is a hydrated oxide. and Alz (1 to 20% by weight converted to h (based on TiO□), preferably 2 to 1O
% by weight (based on TiO□). If the amount is too small than the above range, discoloration and deterioration of the dispersion medium resin will occur, for example, when this material is dispersed in a resin or the like. Moreover, if this amount is too large, the ultraviolet shielding property will be reduced, which is disadvantageous.

The composition of the present invention has a gii of 11 to 20% by weight based on the resin, etc.
(based on solid content such as resin) to make it substantially transparent and block ultraviolet rays. If the mixing amount is less than the above range, sufficient ultraviolet ε shielding properties will not be obtained, and if it is too large, the transparency will be reduced by 1.
If you are an idiot, you will suffer various disadvantages.

As described above, the composition of the present invention is easily dispersed in resins and the like, and the resulting product has sufficient transparency and ultraviolet shielding properties, and the dispersion medium resin is resistant to discoloration and deterioration. Therefore, when the composition of the present invention is blended into transparent packaging materials, paints, inks, etc., sufficient transparency can be maintained, and packaging materials,
If coloring agents are added to paints, inks, etc., they do not affect the color of the paints, inks, etc., and they cannot be used in food,
When used as a packaging material for medicines, etc., it can prevent deterioration of freshness and deterioration of food, medicine, etc. due to ultraviolet rays. In addition, it can also be used for fillers, viscosity modifiers, and other uses.

Next, a liquid phase method, which is an example of a method for producing the composition of the present invention will be explained. In this production method, non-agglomerated titanic acid is first obtained from an acidic aqueous solution of titanium, such as an aqueous solution of titanium in hydrochloric acid and an aqueous solution of titanium in sulfuric acid. Non-agglomerated titanic acid is non-agglomerated metatitanic acid. This can be obtained by heating and hydrolyzing an aqueous solution of titanium in sulfuric acid, washing and peptizing the coagulated precipitate produced, and obtaining non-agglomerated metatitanic acid; There is a method of obtaining non-agglomerated metatitanic acid by washing and peptizing it.

The method for producing the composition of the present invention specifically takes the following aspects.

"Heating hydrolysis process" - "Peptizing process" = "Calcining process" =
"Deposition Step" Each step of this manufacturing method will be explained.

The "thermal hydrolysis step" is a step of heating and hydrolyzing an acidic aqueous solution of titanium.

This thermal hydrolysis is carried out by adding seed crystals to an acidic aqueous titanium solution and heating it to a temperature near the boiling point (usually around 110'C) for several hours according to a conventional method.

The agglomerated precipitate obtained here is obtained as an aggregate in which many primary particles of metatitanic acid with a particle size of about 0.01 μm are aggregated, and when this is dried as it is, the titanium dioxide at the edge of the pigment with a particle size of 0.1 μm or more is However, the fine powder that is the object of the present invention cannot be obtained, and therefore the next "peptizing step" is required.

As described above, it is desirable that the coagulated precipitate produced by the above-mentioned thermal hydrolysis is easily peptized, and therefore, the conditions for thermal hydrolysis are preferably such that the formation of the precipitate proceeds as quickly and completely as possible, for example. It is effective to add seed crystals, to lower the acidity of the titanium salt aqueous solution as the hydrolysis mother liquor, to raise the reaction temperature, to stop the reaction when the reaction rate becomes low, etc.

"Peptizing treatment" is a process in which coagulated precipitates (agglomerated metatitanic acid) are washed and peptized to obtain non-agglomerated metatitanic acid. In the case of coagulated precipitates obtained from a titanium sulfuric acid solution, this is one method. After washing this coagulated precipitate, it is made into a slurry, neutralized with an alkali such as aqueous ammonia, filtered, washed with water to remove the sulfuric acid radicals remaining inside, and then treated with a strong acid such as hydrochloric acid, nitric acid, or trichloroacetic acid. The same state can also be obtained by adding a basic acid to peptize the product to a p113 or less, preferably p111 to 1.5, or by removing as much of the sulfuric acid radical as possible and then wet-pulverizing the product. As another method, without performing the above-mentioned desulfation root treatment, in the flocculation precipitate,
Peptization can also be carried out by adding a salt, such as barium chloride, which reacts with the sulfate radicals to form an insoluble sulfate salt and at the same time forms a monovalent acid.

In the case of a flocculated precipitate obtained from an aqueous hydrochloric acid solution of titanium, it is easily peptized by filtering and thoroughly washing to remove coexisting salts, and adjusting the pH to 3 or less, preferably 1 to 1.5.

Metatitanic acid after peptization may be dried as it is, but it is better to neutralize it with aqueous ammonia or the like, filter it, wash it with water, and then dry it.
It can be made into a fine powder that does not contain particles of 1μ or more.

In the "calcination process", non-agglomerated metatitanic acid is added to 80% of the particles.
The above is a step of firing at a temperature of 150 to 700° C. to obtain fine powder titanium dioxide having a size within the range of 0.01 to 0.1 μm. If the firing temperature is too low, the quality may become unstable or the amount of residual moisture may increase, resulting in undesirable effects such as pinholes when dispersed in a resin and formed into a coating. give. On the other hand, if the firing is carried out at too high a temperature, the titanium dioxide particles will stick together or sinter, producing coarse particles of 0.1 μm or more, making it impossible to obtain the finely powdered titanium dioxide that is the object of the present invention.

In the "deposition step", the non-agglomerated metatitanic acid obtained in the above step is directly dispersed in water with the titanium dioxide obtained through the above "calcination step" to form an aqueous slurry, and on the surface of these titanium dioxide particles, The process involves depositing specific amounts of hydrated oxides of silicon and/or aluminum. When depositing a hydrated oxide of silicon, for example, the amount of titanium dioxide is 100 to 500 g/7! , preferably 250~
400g/1 (as TiO□) of the titanium dioxide is dispersed in water to form an aqueous slurry, and a water-soluble alkali metal silicate such as sodium silicate is added to this to further disperse the titanium dioxide. After that, an acid such as sulfuric acid, nitric acid, hydrochloric acid, acetic acid, etc. is added to neutralize it, and a hydrated oxide of silicon is deposited on the surface of the titanium dioxide particles.When depositing a hydrated oxide of aluminum, for example, To the aqueous slurry prepared in the same manner as above, sodium aluminate and a dispersant are added as necessary to disperse the titanium dioxide well, and then neutralized with the acid described above to deposit a hydrated oxide of aluminum. There are two methods for depositing a hydrated oxide of silicon and aluminum.One method is to add a water-soluble alkali metal silicate such as sodium silicate to an aqueous slurry prepared in the same manner as above. Add salt;
After well dispersing titanium dioxide, aluminum sulfate,
An acidic, water-soluble aluminum compound such as aluminum chloride is added to neutralize the titanium dioxide particles, thereby depositing a specific amount of hydrated oxides of silicon and aluminum or a composite thereof on the surface of the titanium dioxide particles. Another method is to add an alkali or the like to the aqueous slurry prepared in the same manner as above to adjust the PL+ to around 10, disperse the titanium dioxide well, and then add a water-soluble alkali metal silicate such as sodium silicate. In addition, a specific amount of hydrated oxide of silicon is deposited on the surface of the titanium dioxide particles by neutralization with an acid as described above, and then a water-soluble aluminum compound such as sodium aluminate is added, and then a water-soluble aluminum compound such as sodium aluminate is added. Neutralization with acid deposits a specific amount of hydrated oxide of aluminum.

Note that after the deposition treatment, the deposited hydrated oxide is dried at a temperature of 100° C. or higher. The dried product thus obtained is finished ground by a known finishing grinding method.

Next, examples of the present invention will be described.

Example 1 Aggregated metatitanic acid produced by reacting ilmenite with sulfuric acid and heating and hydrolyzing the resulting titanium sulfate solution
An aqueous slurry containing 30% by weight of i0z was prepared, and this slurry was neutralized to 2117 with aqueous ammonia, and then filtered and washed to remove sulfate radicals. The resulting cake was peptized to pH 1.5 by adding 35% hydrochloric acid, neutralized to pH 7 with aqueous ammonia, filtered, washed and dried at 110°C. This dried product was baked at 400℃ for 2 hours to give a
Finely powdered titanium dioxide with a particle size of ~0.03μ was obtained.

100g of this fine powder was made into an aqueous slurry of Ti (h20%), and 5% of TiO□Sin was added to the slurry based on the weight.
Titanium dioxide was dispersed by adding 5.0 - of sodium silicate solution (SiO
This dispersed slurry was wet milled for an hour and then
Al2 equivalent to 3% by weight as A1.03 on a weight basis
Add 601 ni of aluminum sulfate solution of 350 g/l O to neutralize and deposit hydrated oxide on the surface of the fine powder,
Filter this fine powder, wash it, and dry it at 110°C! Then, this dried product was pulverized using a sample mill. The obtained fine powder titanium dioxide composition had a particle size of 0.01 to 0.03 μ.

This composition was mixed into a transparent rough car (prepared by dissolving trocellulose in a solvent such as toluene) as Ti0z in an amount of 10% by weight (based on solid content such as resin) to obtain a transparent image material. This paint was applied to a glass plate with a 10 mil doctor blade and dried to form an apparently clear coating. The visible light (550 mμ) and ultraviolet (320 mμ) transmittance of the glass plate having this coating film was measured using a Shimadzu double beam spectrophotometer UV-200 (manufactured by:S, i1! Seisakusho). The respective values were 27% and 0%. The transmittance value of each glass plate used here is 85%
and 15%. Further, when the temporary glass having this coating film was left for one week, the coating film did not substantially change color.

Example 2 100g of titanium dioxide calcined at 400°C from Example 1 was made into an aqueous slurry containing 0□20% by weight of Ti.
O□juffi! Sodium silicate solution (S
ing/NazO molar ratio 0.5) by adding 50-
Titanium dioxide was dispersed and wet milled in a quick mill. After that, this dispersed slurry was mixed with 10% dilute sulfuric acid p)1
Neutralized to 6.0. After filtering, washing and drying at 110°C, it was ground in a sample mill. The resulting finely powdered titanium dioxide composition had a particle size of 0.01 to 0.03 microns. A coating film was formed in the same manner as in Example 1, and the visible light and ultraviolet transmittance of the glass plate was measured and found to be 25% and 0%, respectively. As a result of the same test as in Example 1, this sauce film did not substantially change color as in Example 1.

Example 3 The 110° C. dried product of Example 1 was calcined at 250° C. for 2 hours to obtain fine powder titanium dioxide having a particle size of 0.01 to 0.02 μm.

Water was added to this fine powder to obtain a 20% by weight aqueous slurry as Ti1t, and 5% by weight and 3% by weight of SiO2 and AbOi, respectively, were deposited on the surface of the fine powder in the same manner as in Example 1.

The fine powder was then filtered, washed, dried at 110'C, and ground in a sample mill. The resulting finely powdered titanium dioxide composition had a particle size of 0.01 to 0.02 microns. This material was temporarily coated on glass in the same manner as in Example 1, and the transmittance of visible light and ultraviolet rays was measured and found to be 55% and 3%, respectively. Moreover, this coating film did not change color or deteriorate even after being left for one week.

Example 4 100g of titanium dioxide calcined at 400°C from Example 1 was
i0□20% by weight aqueous slurry, in which Til
After adding a sodium aluminate solution corresponding to 5% by weight of AIZ (h) on a t weight basis, wet milling was carried out in a quick mill for 1 hour. A hydrated oxide of aluminum was deposited on the surface of the titanium particles.Then, it was filtered, washed, dried at 110°C, and ground in a sample mill.The obtained fine powder titanium dioxide composition had a particle size of 0.01 to 0.03μ. This material was coated on a glass plate in the same manner as in Example 1, and the transmittance of visible light and ultraviolet rays was measured, and it was 37% and 0%, respectively.
This coating film did not change color or deteriorate even after being left for one week.

Example 5 The 110°C dried product of Example 1 was calcined at 685°C for 1 hour to obtain fine powder titanium dioxide having a particle size of 0.02 to 0.05μ. Thereafter, in the same manner as in Example 1, SiO□ and ^180.
1% by weight and 4% by weight, respectively, were deposited on the surface of fine powder particles, washed, dried and ground.

The success of the obtained fine powder titanium dioxide assembly is 0.02 to 0.0
The particle size was 5μ. This material was temporarily coated on glass in the same manner as in Example 1, and the transmittance of visible light and ultraviolet rays was measured and found to be 35% and 0%, respectively.

This coating film did not discolor or deteriorate even after being left for one month.

Claims (1)

[Claims] Finely powdered titanium dioxide in which silicon and/or aluminum oxides are present on the particle surface,
More than 80% of the titanium dioxide particles are 0.01 to 0.
．． The size is within the range of 1μ, and the amount of silicon and aluminum oxides is SiO_2 and Al_2O, respectively.
A finely powdered titanium dioxide composition having a content of 1 to 20% by weight (based on TiO_2) in terms of _3, which provides transparency and ultraviolet shielding properties when blended into a resin film or molded product. .