JPH10297920A - Production of hydroxystannate and flame retardant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To readily obtain a high-purity product having particle diameter with submicron size, excellent in heat stability and free from production of a double decomposition salt and contamination due to the production by subjection oxide or hydroxide of a second group metal of the periodic table and stannous oxide to wet milling in the presence of an alkali, water and oxygen. SOLUTION: The reaction in this invention comprises, as an elementary process of MSn (OH)6 , reduction of stannous oxide, oxidation of tin oxide represented by the reaction formula Sn O+0.502 →Sn O2 (1), production reaction of sodium stannate represented by the reaction formula Sn O2 +2NaOH+2 H2 O→Na2 Sn (OH)6 (2), production of M(OH)2 base, reaction represented by the reaction formula MO+H2 O→M(OH)2 (3), production of tin stannate and regeneration of NaOH represented by the reaction formula Na2 Sn (OH)6 +M(OH)2 →MSn (OH)6 +2NaOH (4). Overall reaction of (1)+(2)+(3)+(4) is represented by the reaction formula Sn O+0.502 +MO+3H2 O→MSn (OH)6 (5). The reaction is a one stage reaction in which oxidation of stannous oxide to tetravalent tin by oxygen and hydration of tetravalent tin component and the second metal or lead (M) component to complex hydroxide simultaneously progress.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydroxystannate, a method for producing the same, and uses thereof. The present invention relates to a method for producing hydroxystannate having excellent stability during processing. The present invention further relates to a flame retardant comprising the above hydroxystannate.

[0002]

2. Description of the Related Art A coating resin for electric wiring used in home appliances, industrial machinery, computers, and the like to prevent a large social confusion caused by fires in high-rise buildings and cable fires laid in underground malls, which have frequently occurred in recent years. It is required to impart flame retardancy to interior and exterior organic synthetic resins as building materials and building materials. Chlorine-containing polymers are one of the thermoplastic resins that are relatively inflammable, but those that are still sufficiently satisfied in that once the resin molding is lit, it easily self-heats. Absent.

Conventionally, in order to impart flame retardancy to resins,
Various inorganic or organic compounds are blended as flame retardants. Among these flame retardants, antimony trioxide has excellent flame retardancy, but has a problem that once it starts burning, it generates a large amount of smoke.

[0004] It is known that a zinc-based inorganic compound leaves a sticky combustion residue having electrical insulating properties after burning a compounded resin composition, and it is known that zinc borate, zinc stannate, or zinc hydroxystannate is used. Provides the advantage of less smoke.

[0005] Zinc hydroxystannate is also called zinc hexahydroxystannate (IV) and has a chemical composition represented by the following formula: ZnSn (OH) ₆ (3). By heat dehydration, zinc stannate of the formula ZnSnO ₃ (4) is obtained. Conventionally, various methods have been known for the synthesis of hydroxystannate.

JP-A-57-191231 discloses that
It describes a method for producing a stannate, which comprises a step of mixing and reacting a alkoxide of a valent metal and a tin alkoxide and a step of hydrolyzing the reaction product to obtain a hydrous stannate.

[0007] JP-A-5-24834 discloses a method in which an acidic aqueous solution containing stannic ion and zinc ion and an aqueous alkali metal hydroxide solution are mixed, and the mixture is subjected to zinc hydroxystannate precipitation at a final pH of 9 or more. A method for producing a zinc hydroxystannate powder, which comprises producing, filtering and drying the precipitate, is described.

Japanese Patent Application Laid-Open No. Hei 5-24835 discloses that an acidic aqueous solution containing stannic ion and zinc ion and an aqueous solution of ammonium carbonate or ammonium bicarbonate are mixed to form amorphous zinc stannate directly in the aqueous solution. A process for producing a high-purity amorphous zinc stannate powder characterized by filtering and drying the precipitate is described.

Japanese Patent Publication No. 5-501100 discloses a method for producing a metal stannate, which comprises converting a solid metal oxide, metal hydroxide or metal carbonate with an aqueous stannate solution. Recovering the mixed and precipitated metal stannate and adding the solid metal oxide, metal hydroxide or metal carbonate in an amount that stoichiometrically does not substantially exceed the amount of tin. Manufacturing method is described.

[0010]

However, hydroxystannates produced by a known production method generally have a considerably large particle size of several μm and a wide particle size distribution, and also have a dispersibility in a resin. There is still room for improvement in flame retardancy. That is, since the flame retardant action of hydroxystannate and its dehydrated product, stannate, is expressed through the surface of these particles, it is advantageous in terms of the flame retardant action that these particle diameters are small. In addition, if the particle size is fine, the contact with the resin becomes finer and more uniform, and the effect is expected to be increased in this respect as well.

Further, the hydroxystannate obtained by a known production method still has room for improvement in terms of purity and thermal stability. That is, the dehydration endothermic peak of hydroxystannate is
Appearing at approximately 250 ° C., known hydroxystannates have been found to produce weight loss from well below this peak temperature. The temperature range in which the weight loss occurs completely overlaps with the compounding temperature of the resin and the molding temperature of the compounded resin, and therefore, troubles such as foaming of the compounded resin composition are likely to occur.

Accordingly, an object of the present invention is to provide a hydroxystannate having a submicron particle size and excellent thermal stability, and a method for producing the same.

[0013] Another object of the present invention is to provide a method for producing hydroxystannate which is free from the formation of metathesis salts as in the conventional method and is free from contamination thereby, has excellent purity and is easy to produce. To offer.

Still another object of the present invention is to provide a hydroxystannate-based flame retardant which can be easily compounded and dispersed in a resin and is excellent in the thermal stability and flame retardancy of the resin.

[0015]

According to the present invention, an oxide or hydroxide of a metal belonging to Group 2 of the periodic table and tin oxide are provided.
A method for producing hydroxystannate is provided, which comprises wet milling in the presence of alkali, water and oxygen.

According to the present invention, there is also provided a chemical composition represented by the following formula: MSn (OH) ₆ ... (5) wherein M is a metal of Group 2 of the periodic table or lead; A hydroxytin having a volume-based median diameter (D ₅₀ ) in the range of 0.3 to 1.5 μm and a weight loss rate of not more than 2.0% by weight at a temperature up to 200 ° C. in thermogravimetric analysis. An acid salt is provided.

[0017] In the following formula _{MSn (OH) 6 ··· (6} ) formula, M is a Group II metal or lead the Periodic Table, in having a chemical composition expressed, volume-based median diameter (D ₅₀ ) Is in the range of 0.3 to 1.5 μm, and the weight loss rate up to a temperature of 200 ° C. in thermogravimetric analysis is 2.0% by weight or less.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, when an oxide or hydroxide of a metal belonging to Group 2 of the periodic table and stannous oxide are subjected to wet milling in the presence of alkali, water and oxygen, the particle diameter becomes submicron. In addition, it is based on the novel finding that hydroxystannate having excellent thermal stability is produced.

The reaction according to the present invention is represented by the following formula. Elementary reaction process of MSn (OH) ₆ Reduction of stannous oxide Formation of sodium stannate SnO ₂ + 2NaOH + 2H ₂ O → Na ₂ Sn (OH) ₆ (8) M (OH) ₂ Generation of stannate, regeneration of NaOH Na ₂ Sn (OH) ₆ + M (OH) ₂ → MSn (OH) ₆ + 2NaOH (10) (7) + (8) + (9) + (10) In this reaction, oxidation of stannous oxide to tetravalent tin by oxygen and hydration of a complex hydroxide of a tetravalent tin component and a Group 2 metal or lead (M) component of the periodic table simultaneously. It is revolutionary in that it proceeds, ie, it is a one-step reaction.

Water and oxygen present in the reaction system are components consumed in the reaction, and the alkali present in the reaction system is indispensable for the smooth progress of the reaction. It is a catalyst component that is not consumed. In the method of the present invention, wet milling is also indispensable, and if not performed, the reaction will not proceed smoothly. In the reaction of the present invention, submicron hydroxystannate particles with high yield and high purity are produced by the mechanochemical action of wet milling and the catalytic action of alkali. The reaction formula also reveals the feature of not containing any by-product salt.

The hydroxystannate according to the present invention is a submicron particle having a volume-based median diameter (D ₅₀ ) determined by a laser diffraction method of 0.3 to 1.5 μm, particularly 0.4 to 1.5 μm. It has the characteristic of being in the range. The particle size distribution curve of the zinc hydroxy stannate according to the present invention is shown in FIG. 1, the particle size distribution curve of the calcium hydroxy stannate according to the present invention is shown in FIG. 2, and the particle size distribution curve of the commercially available zinc hydroxy stannate is shown in FIG.

From these particle size distributions, the hydroxystannate according to the present invention is not only excellent in the fineness of the particle size as compared with the conventional hydroxystannate, but also in the uniformity of the particle size. It turns out that it is excellent compared with the thing of. In the cumulative distribution from the small particle size side, the particle size of 25% by volume is D25 and the particle size of 75% by volume is D75.
Then, the uniformity of the particle size can be evaluated by the ratio of D25 / D75, but the conventional one has a uniformity of 0.16 (FIG. 3).
Whereas, according to the invention, for example, 0.26 (FIG. 1) for the zinc salt and 0.49 (FIG. 2) for the calcium salt
Met. This proved that the particle size uniformity was excellent.

The hydroxystannate according to the invention has the unexpected fact that the grain size is fine and the crystals are well developed. FIG. 4 shows an X-ray diffraction image of the zinc hydroxystannate of the present invention (of FIG. 1), FIG. 5 shows an X-ray diffraction image of the calcium hydroxystannate of the present invention (of FIG. 2), and FIG. FIG. 6 shows an X-ray diffraction image of zinc stannate (of FIG. 3). From a comparison of these X-ray diffraction images, it can be seen that the crystallinity is higher than that of the conventional one.

Further, the hydroxystannate of the present invention has a weight reduction rate of up to 2.0% by weight, particularly 1.0% by weight or less, up to a temperature of 200 ° C. in thermogravimetric analysis. There is an advantage that it is excellent. FIG. 7 shows a thermogravimetric analysis curve of the zinc hydroxystannate (FIG. 1) according to the present invention.
Is shown in FIG. 8, and the thermogravimetric analysis curve of commercially available zinc hydroxystannate (of FIG. 3) is shown in FIG. Comparison of these thermogravimetric analysis curves shows that the conventional one shows a weight loss of as much as 4% by weight up to 200 ° C., while the present invention shows much lower and higher thermal stability. .

[Synthesis Method] In the present invention, an oxide or hydroxide of zinc, calcium, magnesium, barium or strontium is used as the oxide or hydroxide of a metal belonging to Group 2 of the periodic table. Further, lead oxide such as litharge can also be used.

As the stannous oxide, commercially available tin oxide can be used, and one having a particle size generally in the range of 2 to 100 μm is preferable.

The amount ratio of the oxide or hydroxide of Group 2 metal or lead to the tin oxide is preferably a stoichiometric amount, but is generally several moles less than this amount. The excess or deficiency of about% does not adversely affect the crystallinity of the product.

As the alkali, any alkali can be used, but it is generally preferable to use sodium hydroxide.
It is preferred that the system be present so that the pH in the system is 11 to 14, particularly 12 to 13.

It is preferable that an excess of water is present in the reaction system. In general, it is preferable that water be present in an amount of 5 to 20 times by weight of the raw material. Of course, in the reaction system, liquid components other than water, such as alcohols, ketones, and ethers, may coexist.

Oxygen can be supplied to the reaction system in the form of molecular oxygen gas or air. The presence of oxygen in the reaction system by blowing air is economical, while the use of oxygen gas can significantly increase the reaction rate.

The wet milling is preferably performed using a ball mill, a bead mill, a vibration mill or the like. For example, in the case of a ball mill, a peripheral speed of about 30 to 60 m / min is generally appropriate, although it differs depending on the type of ball.

The wet milling is preferably performed at a temperature of room temperature to 100 ° C., particularly at a temperature of 40 to 90 ° C., and the required reaction time is about 4 to 12 hours.

After the reaction, the product hydroxystannate is subjected to solid-liquid separation, washed with water and dried to obtain a product. Alkali remains in the reaction mother liquor, and this alkali can be used repeatedly in the next reaction.

The obtained hydroxystannate is used in an amount of 200 to 4
Heat dehydration at a temperature of 00 ° C. to obtain a stannate of the formula MSnO ₃ ... (12), which can be used for various purposes.

[Hydroxystannate] The features of the hydroxystannate according to the present invention are as described above. The hydroxystannate has a fine particle diameter, a cubic particle shape and a substantially constant particle shape. The individual particles are present in an independent form with little aggregation. This fact can also be confirmed by electron micrographs. FIG. 10 shows a scanning electron microscope (SEM) photograph of the zinc hydroxystannate according to the present invention (the one shown in FIG. 1).
FIG. 11 shows an SEM photograph of calcium hydroxystannate (of FIG. 2) according to the present invention, and FIG. 12 shows an SEM photograph of commercially available zinc hydroxystannate (of FIG. 3).

The hydroxystannates according to the invention have a bulk density in the range from 0.6 to 0.8 g / cm ³ and the oil absorption of dioctyl phthalate (DOP) is generally in the range from 40 to 60 ml / 100 g. . The refractive index is
Since it differs depending on the type of metal, it cannot be unconditionally specified, but in the case of zinc hydroxystannate, it is in the range of 1.7 to 1.9.

Although it has already been pointed out that these hydroxystannate particles are excellent in dispersibility in a resin, in order to improve the handling property as a powder, fumed silica, fumed alumina, and fumed alumina are used. Flowability improver such as phase method titania,
It can be externally added in an amount of 0.1 to 10% by weight.

[Flame retardant] The hydroxystannate of the present invention comprises:
It can be blended as a flame retardant with various organic polymers such as a thermoplastic resin, an elastomer or a thermosetting resin. The appropriate amount varies depending on the required degree of flame retardancy and the type of the polymer, but is generally from 1 to 50 parts by weight, especially from 1 to 10 parts by weight, per 100 parts by weight of the polymer. Is good.

The reason why hydroxystannate is excellent in the flame retardant effect is that the dehydration and endothermic reaction due to thermal decomposition lowers the combustion temperature. The gas phase reaction due to the partial volatilization of zinc and tin in a high temperature region leads to a reduction in carbon monoxide, and a synergistic effect of suppressing the combustion gas and the shell effect is obtained. The divalent metal, particularly zinc, etc. contained in the stannate acts as a catalyst for the dehalogenation reaction, promotes the formation of a carbonized layer, suppresses the generation of smoke, and the like. Stannates are excellent in these effects, and some of them have a remarkable improvement in oxygen index.

As the thermoplastic resin, not only a resin synthesized using a metallocene catalyst, but also, for example, low density polyethylene, high density polyethylene, polypropylene, poly 1
Polyolefins such as random or block copolymers of α-olefins such as butene, poly-4-methyl-1-pentene or ethylene, propylene, 1-butene and 4-methyl-1-pentene; ethylene-vinyl acetate copolymer Styrene, such as copolymers, ethylene-vinyl alcohol copolymers, ethylene-vinyl compound copolymers such as ethylene-vinyl chloride copolymers, polystyrene, acrylonitrile-styrene copolymers, ABS, α-methylstyrene-styrene copolymers Resin, polyvinyl chloride, polyvinylidene chloride, polyvinyl chloride / vinylidene chloride copolymer, polyvinyl compounds such as polymethyl acrylate, polymethyl methacrylate, nylon 6, nylon 6-6, nylon 6
Polyamides such as -10, nylon 11, nylon 12,
Resins of thermoplastic polyesters such as polyethylene terephthalate and polybutylene terephthalate, polycarbonates, polyphenylene oxide and the like, or mixtures thereof may be used.

Examples of the elastomer polymer include nitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), polybutadiene (BR), polyisoprene (IIB), butyl rubber, natural rubber, ethylene- Propylene rubber (EP
R), ethylene-propylene-diene rubber (EPD)
M), polyurethane, silicone rubber, acrylic rubber, etc .; thermoplastic elastomers such as styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, hydrogenated styrene-butadiene-styrene block copolymer, hydrogen Styrene-isoprene-styrene block copolymer.

On the other hand, examples of the thermosetting resin include phenol-formaldehyde resin, furan-formaldehyde resin, xylene-formaldehyde resin, ketone-formaldehyde resin, urea-formaldehyde resin,
Examples include melamine-formaldehyde resin, alkyd resin, unsaturated polyester resin, epoxy resin, bismaleimide resin, triallyl cyanurate resin, thermosetting acrylic resin, silicone resin, urethane resin and the like. These resins may be used alone or in combination of two or more.

The hydroxystannate of the present invention is particularly effective when blended with a chlorine-containing polymer. Examples of such a chlorine-containing polymer include polyvinyl chloride, polyvinylidene chloride, chlorinated polyethylene, and the like. Chlorinated polypropylene, chlorinated rubber, vinyl chloride-vinyl acetate copolymer, vinyl chloride-ethylene copolymer, vinyl chloride-propylene copolymer, vinyl chloride-styrene copolymer, vinyl chloride-isobutylene copolymer, vinyl chloride -Vinylidene chloride copolymer, vinyl chloride-styrene-acrylonitrile copolymer, vinyl chloride-butadiene copolymer, vinyl chloride-propylene chloride copolymer, vinyl chloride-vinylidene chloride-vinyl acetate terpolymer, vinyl chloride -Styrene-
Maleic anhydride terpolymer, vinyl chloride-acrylate copolymer, vinyl chloride-maleate copolymer, vinyl chloride-methacrylate copolymer,
Vinyl chloride-acrylonitrile copolymer, polymers such as internally plasticized polyvinyl chloride, and these chlorine-containing polymers and polyethylene, polybutene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, polystyrene, acrylic resin And acrylonitrile-butadiene-styrene copolymer, acrylate-butadiene-styrene copolymer and the like.

The flame retardant of the present invention may be used alone or as another flame retardant component, such as oxides, hydroxides, sulfides and zinc borates of antimony, zircon and molybdenum, aluminum borate, aluminum hydroxide and magnesium hydroxide. Can be combined with resin. Further, the surface of the stannate of the present invention may be coated and used under grinding conditions using these flame retardants.

Various additives known per se, such as stabilizers, plasticizers, antioxidants, light stabilizers, lubricants, antistatic agents, antifogging agents, nucleating agents, fillers, are added to the polymer. Etc. can be blended. These additives may be previously blended in the polymer or the flame retardant of the present invention, or may be blended at the same time when the flame retardant of the present invention and the polymer are kneaded.

[0046]

EXAMPLES In the following examples, measurements were made by the following methods.

(1) Average particle size and particle size Particle Size Analyzer Model LS manufactured by Coulter
The average particle size and particle size were measured using 230.

(2) X-ray Diffraction Measurement was performed with Cu-Kα using a Geigerflex RAD-B system manufactured by Rigaku Corporation. Target Cu filter Curved crystal graphite monochromator Detector SC voltage 40KV Current 20mA Count full scale 700c / s Smoothing point 25 Scan speed 2 ° / min Step sampling 0.02 ° Slit DS1 ° RS0.15mm SS1 ° Illumination angle 6 °

(3) Differential Thermal Analysis and Measurement of Weight Loss The measurement was performed using an SSC-5200TG-DTA system manufactured by Seiko Instruments Inc. The measurement conditions were the standard substance α
-Loss on heating of samples up to 500 ° C in Al ₂ O ₃ (% by weight)
Was measured.

(4) SEM Measurement The SEM was measured using an S-570 scanning electron microscope manufactured by Hitachi, Ltd.

(5) Chemical analysis The chemical analysis was carried out in accordance with the lime chemical analysis method of JIS R9011.

After measuring various physical properties of the stannate, the soft PV
C, and the stannate was measured for flame retardancy, stability performance and dispersibility. (Blending of soft PVC) 100 parts by weight of PVC (P1050) 50 parts by weight of dioctyl phthalate 4 parts by weight of tribasic lead sulfate 5 parts by weight of stannate (Soft PVC sheet preparation conditions) The above-mentioned composition is 155 with a 3.5-inch roll mill. After kneading for 6 minutes at 170 ° C,
The sheet was pressed at 50 kg / cm ² for 5 minutes to produce a sheet having a thickness of 1 mm.

(6) Limiting oxygen index (LOI) Using a candle method combustion tester manufactured by Toyo Seiki Seisaku-sho, Ltd., the limiting oxygen index (LOI value%) was measured according to the JIS K 7201B method, and the flame retardancy was measured. Was evaluated.

(7) Specific Visual Density (NBS) Using an NBS smoke test device manufactured by Toyo Seiki Seisaku-sho, Ltd.
The sample PVC sheet was heated at a thermal radiation amount of 2.5 W / cm ² to emit smoke, and the smoke intensity was evaluated using a specific visual density calculated from the white light transmittance of the smoke.

(8) Dispersibility The following formulation is kneaded with a heated roll at 155 ° C. for 5 minutes, and further visually formed into a sheet having a thickness of 0.5 mm. Incorporation Vinyl chloride resin (degree of polymerization: 1050) 100 parts by weight DOP 50 parts by weight Lead stearate 0.2 parts by weight Sample 3 parts by weight Evaluation criteria ○: Good dispersibility △: Slightly poor dispersibility ×: Poor dispersibility

(9) Gear Oven Heat Resistance (GO Heat Resistance Test) The produced PVC sheet was heated in a gear oven at 185 ° C., and the time until the sheet was blackened and deteriorated was measured.

Examples of the present invention will be described below.

(Example 1) 70.4 g of stannous oxide and 41.1 g of zinc oxide were added to 10.4 g of sodium hydroxide and 1000 m of water.
The reaction was carried out for 6 hours while blowing air at 1 L / min in a pot mill. At this time, the pH was 13.1. The resulting white precipitate was filtered, washed, and
Drying was carried out day and night to obtain zinc hydroxystannate. When this powder was measured by an X-ray diffraction method, it was confirmed to be zinc hydroxystannate as shown in FIG. Further, as shown in FIG. 1, the particle size distribution of this powder is a particle having an average particle diameter of 0.6 μm and having no coarse particles, and as shown in FIG. Met.
Table 2 shows the physical properties of various powders, and Table 1 shows the flame retardancy of the soft PVC.

Example 2 Stannous oxide (70.9 g), calcium hydroxide (38.6 g), caustic soda (10.4 g) and water (1) were added.
000 ml was added, and the reaction was performed in the same procedure as in Example 1. The pH at this time was 12.8. The produced white precipitate was filtered, washed, and dried at 90 ° C. for one day to obtain calcium hydroxystannate. When this powder was measured by X-ray diffraction, it was confirmed to be calcium hydroxystannate as shown in FIG. The particle size distribution of the powder was fine particles having an average particle diameter of 0.4 μm, as shown in FIG. 2 (see SEM FIG. 11). Table 2 shows the physical properties of various powders, and Table 1 shows the flame retardancy of the soft PVC.

Comparative Example 1 Water 7 was added to 53.3 g of sodium stannate.
120 ml of an aqueous solution containing 27.8 g of tin chloride was added dropwise to the solution containing 00 ml with stirring at room temperature to form a white precipitate of zinc hydroxystannate. The pH at this time is 7.
It was 2. The resulting white precipitate is filtered, washed, and 90 ° C.
And dried all day and night to obtain zinc hydroxystannate. When this powder was measured by X-ray diffraction, it was confirmed to be zinc hydroxystannate as shown in FIG. 14 (FIG. 1).
No. 3, particle size distribution, differential thermal analysis in FIG. 15, and SEM photograph in FIG. 16). Table 2 shows the physical properties of various powders, and Table 1 shows the flame retardancy of the soft PVC.

Comparative Example 2 A commercially available zinc stannate was analyzed. FIG. 3 shows the particle size distribution, FIG. 6 shows the X-ray diffraction, FIG. 9 shows the differential thermal analysis, and FIG. 12 shows the SEM photograph. Table 2 shows the physical properties of various powders, and Table 1 shows the flame retardancy of the soft PVC.

[0062]

[Table 1]

[0063]

[Table 2]

[Brief description of the drawings]

FIG. 1 is a particle size distribution curve of zinc hydroxystannate of Example 1.

FIG. 2 is a particle size distribution curve of calcium hydroxystannate of Example 2.

FIG. 3 is a particle size distribution curve of zinc hydroxystannate of Comparative Example 2.

FIG. 4 is an X-ray diffraction image of zinc hydroxystannate of Example 1.

FIG. 5 is an X-ray diffraction image of calcium hydroxystannate of Example 2.

FIG. 6 is an X-ray diffraction image of zinc hydroxystannate of Comparative Example 2.

FIG. 7 is a thermogravimetric analysis curve of zinc hydroxystannate of Example 1.

FIG. 8 is a thermogravimetric analysis curve of the calcium hydroxystannate of Example 2.

FIG. 9 is a thermogravimetric analysis curve of zinc hydroxystannate of Comparative Example 2.

FIG. 10 is an SEM image (magnification: 20000 times) of zinc hydroxystannate of Example 1.

FIG. 11: SE of calcium hydroxystannate of Example 2
It is an M image (magnification: 20000 times).

FIG. 12 is a SEM image (magnification: 20000 times) of zinc hydroxystannate of Comparative Example 2.

13 is a particle size distribution curve of zinc hydroxystannate of Comparative Example 1. FIG.

FIG. 14 is an X-ray diffraction image of zinc hydroxystannate of Comparative Example 1.

FIG. 15 is a thermogravimetric analysis curve of zinc hydroxystannate of Comparative Example 1.

FIG. 16 is an SEM image (magnification: 20000 times) of zinc hydroxystannate of Comparative Example 1.

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI // C01G 9/00 C01G 9/00 B

Claims (7)

[Claims] 1. A method for producing a hydroxystannate, comprising wet milling an oxide or hydroxide of a metal belonging to Group 2 of the periodic table with stannous oxide in the presence of alkali, water and oxygen. Method. 2. The method according to claim 1, wherein the alkali is present so that the pH in the system is 11 to 14. 3. The method according to claim 1, wherein oxygen is present by blowing air. 4. The oxide or hydroxide of a metal belonging to Group 2 of the periodic table is an oxide or hydroxide of zinc, calcium, magnesium, barium or strontium.
The manufacturing method as described. 5. The method according to claim 1, wherein the wet milling is performed at a temperature of room temperature or higher and 100 ° C. or lower. 6. The following formula MSn (OH) ₆ ... (1) wherein M is a metal of the second group of the periodic table or lead, and has a volume-based median diameter ( D ₅₀₎ is in the range of 0.3 to 1.5 [mu] m, and hydroxy stannates, wherein the weight reduction rate of up to temperature 200 ° C. in thermogravimetric analysis is 2.0 wt% or less. 7. The following formula MSn (OH) ₆ ... (2) wherein M is a metal of the second group of the periodic table or lead, and has a volume-based median diameter ( D ₅₀ ) in the range of 0.3 to 1.5 μm, and the weight loss rate up to a temperature of 200 ° C. in thermogravimetric analysis is 2.0% by weight or less.