JP2003146651A - Li-Al-BASED LAYERED COMPOSITE HYDROXIDE GRAIN POWDER AND PRODUCTION METHOD THEREFOR - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide Li-Al-based layered composite hydroxide grain powder which has a high planar ratio (planar face diameter/thickness). SOLUTION: The Li-Al-based layered composite hydroxide grain powder has a mean sheet face diameter of 0.05 to 2.0 μm, and a planar ratio (planar face diameter/thickness) of 20 to 100, and contains the hydroxide of silicon or the oxide of silicon. The Li-Al-based layered composite hydroxide grain powder in which the content of the hydroxide of silicon or the oxide of silicon is 0.1 to 2.5 wt.% as a silicon content can be obtained, in a method where an alkaline aqueous solution containing anions, a lithium salt aqueous solution, and an aluminum compound capable of forming aluminum ions are mixed to form a mixed solution having a pH value in the range of 8 to 14, and the mixed solution is thereafter matured in the temperature range of 60 to 105 deg.C to produce Li-Al-based layered composite hydroxide grains, by allowing the silicon compound to exist in the process of the maturation.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a plate ratio (plate surface diameter /
The present invention relates to a Li-Al-based layered double hydroxide particle powder having a large thickness).

[0002]

2. Description of the Related Art As is well known, there are various compounds other than clay minerals as layered compounds. Among them, layered double hydroxides such as hydrotalcite (Layered Dope) are included.
The double hydroxide) has a structure capable of inserting various ions, molecules and the like between the layers, and thus can exhibit an anion exchange function.

In general, the structure of hydrotalcite is described in "[M 2 ⁺ _1-x M ³⁺ _x (OH)" as described in Chemical Society of Japan, 1995 (8), p622-628.
₂ ] _x ⁺ [A ^n- _{x / n} · yH ₂ O] _x ^- where M ²⁺
Is a divalent metal ion such as Mg ²⁺ , Co ²⁺ , Ni ²⁺ , Zn ²⁺ , M ³⁺ is Al ³⁺ , Fe ³⁺ , Cr.
Trivalent metal ions such as ^{3+, A} n-is, ^OH -, C
An anion having a valence of 1 ⁻ , CO ₃ ²⁻ , SO ₄ ^2−, or the like, and x is generally in the range of 0.2 to 0.33. The crystal structure has a laminated structure including a two-dimensional basic layer in which regular octahedral brucite units having a positive charge are arranged and an intermediate layer having a negative charge. It is said that.

Hydrotalcite has been used as an antacid for a long time, but since then, it has been developed into various applications utilizing the anion exchange function. For example, an ion exchange material, an adsorbent, a deodorant, It is used in a wide variety of applications such as stabilizers for resins and rubbers such as polyethylene, polypropylene and vinyl chloride, as well as paints, various catalysts, agricultural films and inks.

In addition, at present when environmental consideration is required, it is desired to use an additive that does not contain a toxic metal, so that it is not toxic and stable. It can be said that the compound hydrotalcite can meet such expectations.

[0006] In recent years, hydrotalcites have been synthesized with a much wider variety of combinations of anions and cations than naturally occurring minerals, and these are collectively called hydrotalcite-like compounds or layered double hydroxides. Has been done.

These are non-stoichiometric compounds represented by a general formula broader than the above composition formulas, and in the combination of metal ions, in addition to divalent-trivalent, monovalent-trivalent, divalent- Tetravalent,
Bivalent-divalent, trivalent-trivalent, trivalent-tetravalent, etc. are known. A typical monovalent-trivalent combination is a Li-Al-based layered double hydroxide.

The Li-Al layered double hydroxide is [Al ₂ L
^{_{i (OH) 6] + X}} - · nH denoted ₂ O. Where X
⁻ Represents an anion between layers. The crystal structure is Clays and Clay Minerals
Clay Minerals) (1982) Volume 30
p180-184, Al is Gibbs
It is arranged in an ite structure, and its vacancy (Vacancy) is L
The i-ion occupies a two-dimensional layer and has a structure in which an anion is incorporated between layers in order to supplement the charge. The X-ray diffraction pattern shows a 2H type laminated structure instead of the 3R type laminated structure shown by hydrotalcite (Mg ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O). It is also known that Li is regularly arranged in the basic layer containing Li and Al.

The Li-Al layered double hydroxide particle powder generally has a plate-like shape, and the particles are easily oriented due to the shape. Therefore, when it is used as a coating film, it has excellent properties of covering and shielding, and is also effective as a reinforcing agent for the coating film. Therefore, undercoat paint for automobiles,
It is promising for applications such as anticorrosive materials, paints with gas barrier properties, and reinforcing agents for magnetic tapes. In order to obtain a coating film having a high coating property, shielding property, and strength, Li-Al layered double hydroxide particle powder having a large plate ratio and excellent orientation is required.

The Li-Al layered double hydroxide particles powder can be produced by reacting a water-soluble lithium salt or lithium hydroxide with a water-soluble aluminum salt in the presence of a water-soluble carbonate and an alkali ( JP-A-5-1790
52), a method of reacting Gibbsite type aluminum hydroxide fine particles with a lithium salt of carbonic acid or a combination of a lithium compound capable of forming lithium carbonate and a carbonate in the presence of water (JP-A-9-142835). Gazette), a method of obtaining a complex hydroxide condensed silicate by subjecting an anion contained in the Li-Al layered double hydroxide particle powder to a substitution reaction with a condensed silicate ion.
No. 3), a lithium salt is used for either one of the alkali metal aluminate and the alkali metal salt and / or alkali metal hydroxide other than the alkali metal aluminate,
A method of reacting an alkali metal aluminate with an alkali metal salt and / or an alkali metal hydroxide other than the alkali metal aluminate in water (Japanese Patent Laid-Open No. 10-17322).
No. gazette) is known.

Further, lithium carbonate is used as a lithium raw material,
A method in which aluminum chloride is used as an aluminum raw material, these are reacted in the presence of sodium carbonate and sodium hydroxide, and the reaction product is treated with a higher fatty acid or a surfactant to improve the degree of orientation (Japanese Patent Application Laid-Open No. H7-18753). No. 3,003,133) is known.

[0012]

Li- having a large plate ratio
The Al-based layered double hydroxide particle powder is currently most demanded, but Li-Al-based layered double hydroxide particles capable of sufficiently exhibiting the characteristic that the particles are easily oriented due to the plate shape. No powder has yet been provided.

That is, according to the production methods described in the above publications, it is difficult to obtain Li-Al-based layered double hydroxide particles having a large plate ratio, and it is difficult to say that the orientation is excellent.

Also, in the above-mentioned Japanese Patent No. 2852563, a method of obtaining a complex hydroxide condensed silicate by substituting the condensed silicate for the anion contained in the Li-Al layered double hydroxide particles powder. However, it is difficult to say that it is difficult to obtain a particle powder having a large plate ratio and the orientation is excellent.

Therefore, according to the present invention, Li- having a large plate ratio is used.
A technical problem is to obtain an Al-based layered double hydroxide particle powder.

[0016]

The above technical problems can be achieved by the present invention as follows.

That is, according to the present invention, an alkaline aqueous solution containing an anion, an aqueous lithium salt solution and an aluminum compound capable of forming aluminum ions are mixed to prepare a mixed solution having a pH value in the range of 8 to 14, and then the mixed solution is mixed. 60 solution
Li-Al by aging in the temperature range of ~ 105 ℃
In the method for producing layered double hydroxide particles, S is added to the total moles of lithium and aluminum.
A method for producing a Li-Al-based layered double hydroxide particle powder, wherein 0.1 to 10 mol% of a silicon compound in terms of i is present during the aging (Invention 1).

In the present invention, an alkaline aqueous solution containing anions, an aqueous lithium salt solution and an aluminum compound capable of forming aluminum ions are mixed to prepare a mixed solution having a pH value in the range of 10 to 14, and then the mixed solution is mixed. 6 solution
Aging is performed in a temperature range of 0 to 105 ° C. to generate core particles of Li—Al-based layered double hydroxide particles, and then an aqueous lithium salt solution and aluminum ions are formed in an aqueous suspension containing the core particles. After adding the obtained aluminum compound,
In the method for producing Li-Al layered double hydroxide particles by aging the pH value in the range of 8 to 14 and the temperature in the range of 60 to 105 ° C, the total number of moles of the total lithium and the total aluminum is On the other hand, 0.1 in terms of Si
A method for producing a Li-Al-based layered double hydroxide particle powder, characterized in that 10 mol% of a silicon compound is present during the aging (Invention 2).

In the present invention, the average plate surface diameter is 0.05 to.
2.0 μm and plate ratio (plate surface diameter / thickness) of 20 to 1
00, a Li-Al-based layered double hydroxide particle powder containing a silicon hydroxide or a silicon oxide, wherein the content of the silicon hydroxide or the silicon oxide is as the silicon content. Li-Al which is 0.1 to 2.5% by weight
It is a system layered double hydroxide particle powder (Invention 3).

The structure of the present invention will be described in more detail as follows.

First, the Li-Al-based layered double hydroxide particle powder according to the present invention will be described.

The particle shape of the Li-Al layered double hydroxide particle powder according to the present invention is plate-like.

The Li-Al layered double hydroxide particle powder according to the present invention has an average plate surface diameter of 0.05 to 2.0 μm.
When the plate surface diameter is less than 0.05 μm, the dispersibility in the paint is insufficient. If it exceeds 2.0 μm, industrial production becomes difficult. Preferably 0.07-
It is 2.0 μm.

The Li-Al layered double hydroxide particles according to the present invention have a thickness of preferably 0.005 to 0.070 μm, more preferably 0.005 to 0.065 μm.

The plate ratio (plate surface diameter / thickness) of the Li-Al layered double hydroxide particle powder according to the present invention is 20 to 100. When the plate ratio is less than 20, the orientation is insufficient, which is not preferable. If it exceeds 100, industrial production becomes difficult. It is preferably 25 to 100.

The BET specific surface area value of the Li-Al layered double hydroxide particles according to the present invention is preferably ²⁰ to 130 m ² / g, more preferably 20 to 120 m ² / g.

The content of the silicon hydroxide or the silicon oxide contained in the Li-Al layered double hydroxide particles according to the present invention is 0.1 to 2.5 as the silicon content.
%, Preferably 0.1 to 2.2% by weight.

When the silicon content is less than 0.1% by weight, the effect of improving the orientation in the coating film does not appear. If it exceeds 2.5% by weight, the effect is saturated and it is meaningless to add more than necessary.

The composition of the Li-Al layered double hydroxide particles according to the present invention is as follows.

[Al ₂ Li (OH) ₆ ] ⁺ X ⁻ · nH ₂ O X ⁻ : Anion between layers, n ≧ 0

The anion (X) is not particularly ^specified, OH -, _CO ^{3 2-} and the like, _preferably, ^{CO 3 2-.}

The orientation degree of the Li-Al layered double hydroxide particles according to the present invention is preferably 65% or more, more preferably 70% or more. The degree of orientation was measured by the method described below.

Next, the method for producing the Li-Al layered double hydroxide particles according to the present invention will be described.

First, a method for producing the Li-Al-based layered double hydroxide particle powder according to the present invention 1 will be described.

The alkaline aqueous solution containing anions in the present invention is preferably a mixed alkaline aqueous solution of an aqueous solution containing anions and an alkaline hydroxide solution.

The aqueous solution containing anions is preferably an aqueous sodium carbonate solution.

As the alkali hydroxide aqueous solution, sodium hydroxide aqueous solution is preferable.

As the lithium salt aqueous solution in the present invention, lithium hydroxide, lithium carbonate, lithium chloride, lithium sulfate, lithium acetate, lithium nitrate or the like can be used. Preferred are lithium sulfate and lithium carbonate.

As the aluminum compound in the present invention, aluminum sulfate, aluminum hydroxide, aluminum oxyhydroxide (boehmite), aluminum chloride,
Sodium aluminate, aluminum acetate, aluminum nitrate and the like can be used. Aluminum sulfate and aluminum hydroxide are preferable.

The silicon compound used in the present invention is 3
Water glass, sodium orthosilicate, sodium metasilicate, colloidal silica and the like can be used. No. 3 water glass is preferable.

The order of mixing the anion-containing alkaline aqueous solution, the lithium salt aqueous solution and the aluminum compound capable of forming aluminum ions is not particularly limited, and each aqueous solution or compound may be mixed at the same time.

The order of mixing the alkaline aqueous solution containing the anion, the aqueous lithium salt solution and the aluminum compound capable of forming aluminum ions is not particularly limited, and the respective aqueous solutions or compounds may be mixed at the same time.

The silicon compound may be left in the reaction solution during the aging. The addition method of the silicon compound is any of an alkaline aqueous solution containing anions, a lithium salt aqueous solution, a method of adding to each raw material of an aluminum compound capable of forming aluminum ions, a method of adding to a mixed solution, and a method of adding during aging. But it's okay. In addition,
When it is added during aging, it is preferably added by half the total aging time.

When each aqueous solution or compound is added, the aqueous solution or compound may be added at once or continuously.

The concentration of the lithium salt in the reaction solution obtained by mixing the alkaline aqueous solution containing the anion, the lithium salt aqueous solution and the compound capable of forming aluminum ions is not more than 0.
04-1.0 mol / l is preferable, more preferably 0.05-0.9 mol / l, and the aluminum compound is preferably 0.08-2.0 mol / l, more preferably 0.10-1.8 mol. / L, the anion is preferably 0.04 to 1.7 mol / l, more preferably 0.05 to 1.5 mol / l, and the aqueous alkali hydroxide solution is preferably 0.5 to 8 mol / l, It is preferably 0.8 to 6 mol / l. The molar ratio of lithium to be added and aluminum (Li / Al) is 0.48 to
0.75 is preferable.

The amount of silicon compound added is 0.1 to 10 relative to the total number of moles of lithium and aluminum added.
mol% is preferable, and more preferably 0.15 to 9 mo
1%.

The temperature during the aging reaction is 60 to 105 ° C, preferably 65 to 105 ° C. Even when the temperature is lower than 60 ° C., Li—Al-based layered double hydroxide particle powder is produced, but the crystallinity is remarkably reduced, so that Li having a large plate ratio is used.
-Al-based layered double hydroxide particles cannot be obtained. 1
If the temperature exceeds 05 ° C, a pressure resistant container such as an autoclave is required, which is not economical.

The pH value during the aging reaction is preferably 8 to 14, and more preferably 8.2 to 14. When the pH value is less than 8, Li-Al layered double hydroxide particles having a large plate ratio cannot be obtained.

The reaction time of the aging reaction is preferably 2 to 24 hours. When the aging time is less than 2 hours, it is difficult to obtain Li-Al-based layered double hydroxide particles having a large plate ratio. 24
Aging over time is not economical.

After completion of the reaction, Li-Al type layered double hydroxide particles powder can be obtained by washing with water and drying by a conventional method.

Next, the method for producing the Li-Al-based layered double hydroxide particle powder according to the present invention 2 will be described.

The method for producing the Li-Al-based layered double hydroxide particle powder according to the second aspect of the present invention is to mix an alkaline aqueous solution containing anions, an aqueous lithium salt solution and an aluminum compound capable of forming aluminum ions to obtain a pH value. Is 10
~ 14 to the mixed solution, and then the mixed solution of 60 ~
A primary reaction in which the core particles of Li-Al-based layered double hydroxide particles are generated by aging in a temperature range of 105 ° C, and an aqueous suspension containing the core particles obtained in the primary reaction is added to a lithium salt aqueous solution. And an aluminum compound capable of forming aluminum ions, and a secondary reaction in which the pH value is aged in the range of 8 to 14 and the temperature is aged in the range of 60 to 105 ° C. The primary reaction and the secondary reaction are added. During the aging, 0.1 to 10 mol% of a silicon compound in terms of Si is present with respect to the total number of moles of lithium and aluminum.

The silicon compound may be allowed to be present in the reaction solution during the aging of the primary reaction, the secondary reaction, or the primary reaction and the secondary reaction. The method for adding the silicon compound is as follows: an alkaline aqueous solution containing anions, an aqueous lithium salt solution, and an aluminum compound capable of forming aluminum ions. Any of a method of adding during aging, a method of adding to a reaction solution after completion of the primary reaction, a method of adding to any of the starting materials for the secondary reaction, and a method of adding during aging of the secondary reaction may be used. Preferably, a method of adding to each of the above raw materials in advance, a method of adding to a mixed solution of the first reaction, a method of adding during aging of the first reaction, 1
It is a method of adding to the reaction solution in which the next reaction is completed, or a method of adding to any of the raw materials of the secondary reaction. When it is added during aging, it is preferable to add it by half the aging time.

As the alkaline aqueous solution containing the anion in the present invention, the same aqueous solution as the alkaline aqueous solution containing the anion in the first invention can be used.

The lithium salt aqueous solution, the aluminum compound and the silicon compound in the present invention are the same as those in the present invention 1
The same aqueous solution or compound as the lithium salt aqueous solution, aluminum compound and silicon compound in the above can be used.

In the first reaction, the order of mixing the anion-containing alkaline aqueous solution, the lithium salt aqueous solution and the aluminum compound capable of forming aluminum ions is not particularly limited, and each aqueous solution or compound is mixed at the same time. May be.

When each aqueous solution or compound is added, the aqueous solution or compound may be added all at once or continuously.

The concentration in the reaction solution obtained by mixing the alkaline aqueous solution containing the anion, the lithium salt aqueous solution and the compound capable of forming aluminum ions in the first reaction is
The lithium salt is preferably 0.04 to 1.0 mol / l,
More preferably 0.05 to 0.9 mol / l, the aluminum compound is preferably 0.08 to 2.0 mol / l,
More preferably 0.10 to 1.8 mol / l, the anion is preferably 0.04 to 1.7 mol / l, more preferably 0.05 to 1.5 mol / l, and the aqueous alkali hydroxide solution is 0.5 to 8 mol. / L is preferable, and more preferably 0.8 to 6 mol / l.

The temperature during the aging reaction in the primary reaction is 60.
˜105 ° C., preferably 65˜105 ° C.
Even when the temperature is lower than 60 ° C., Li—Al-based layered double hydroxide particles are generated, but the crystallinity is significantly reduced. Can't get If the temperature exceeds 105 ° C, a pressure resistant container such as an autoclave is required, which is not economical.

The pH value during the aging reaction in the primary reaction is 1
It is 0 to 14, preferably 10.2 to 14. p
When the H value is less than 10, core particles of Li-Al layered double hydroxide particles having a large plate ratio cannot be obtained.

The reaction time of the aging reaction in the primary reaction is 2
~ 24 hours are preferred. When the aging time is less than 2 hours, it is difficult to obtain core particles of Li-Al layered double hydroxide particles having a large plate ratio. Aging for more than 24 hours is not economical.

The Li-Al layered double hydroxide core particles obtained by the primary reaction preferably have a plate surface diameter of 0.03 to 1.80 μm and a thickness of 0.003 to 0.05 μm.
The BET specific surface area value is preferably 25 to 160 m ² / g.

In the secondary reaction, the total molar number of lithium and aluminum added is preferably 0.90 or less with respect to the total molar number of lithium and aluminum added in the primary reaction. It is more preferably 0.85 or less. 0.9
If it exceeds 0, a large amount of fine particles are precipitated, and Li-Al layered double hydroxide particles having a large plate ratio cannot be obtained.

In the secondary reaction, the order of adding the lithium salt aqueous solution and the aluminum compound capable of forming aluminum ions is not particularly limited, and each may be added simultaneously.

When each aqueous solution or compound is added, the aqueous solution or compound may be added all at once or continuously.

The concentration of the lithium salt in the secondary reaction is 0.02 to 0.02 in the reaction solution obtained by mixing the lithium salt aqueous solution and the aluminum compound capable of forming aluminum ions.
0.5 mol / l is preferable, and 0.02 is more preferable.
~ 0.45 mol / l, the aluminum compound capable of forming aluminum ions is preferably 0.04 to 1.0 mol / l, and more preferably 0.04 to 0.95 mol / l.
It is l. The ratio of the total number of moles of lithium and the total number of moles of aluminum added in the first and second reactions (Li / A
1) is preferably 0.48 to 0.75.

The amount of the silicon compound added in the present invention 2 is 0.1 to 10 mo with respect to the total number of moles of lithium and aluminum added in the primary reaction and the secondary reaction.
1% is preferable, and more preferably 0.15 to 9 mol%
Is.

The temperature during the aging reaction in the secondary reaction is 60.
˜105 ° C., preferably 65˜105 ° C.
Even when the temperature is lower than 60 ° C., Li—Al-based layered double hydroxide particle powder is produced, but the crystallinity is remarkably lowered and the degree of orientation is lowered. If the temperature exceeds 105 ° C, a pressure resistant container such as an autoclave is required, which is not economical.

The pH value during the aging reaction in the secondary reaction is 8
It is -14, preferably 8.2-14. When the pH value is less than 8, Li-Al layered double hydroxide particles having a large plate ratio cannot be obtained.

The reaction time of the aging reaction in the secondary reaction is 2
~ 24 hours are preferred. When the aging time is less than 2 hours, it is difficult to obtain Li-Al-based layered double hydroxide particles having a large plate ratio. Aging for more than 24 hours is not economical.

Further, in the present invention, it is also possible to carry out a tertiary reaction under the same reaction conditions as the secondary reaction, and further to obtain Li-Al-based layered double hydroxide particles powder in which the surfaces of the core particles are coated.

After the completion of the secondary reaction, the powder is washed with water and dried by a conventional method to obtain Li-Al type layered double hydroxide particles powder.

In the present invention, the obtained Li-A
1 to 24 layer-type double hydroxide particles powder in the temperature range of 120 to 350 ° C. in air or in an atmosphere of N ₂ , He or the like.
You may heat-process for decrystallization water treatment.

In the present invention, the obtained Li-
The Al-based layered double hydroxide particle powder may be surface-coated with one or more surface-coating agents selected from higher fatty acids, organic silane compounds, and rosins.

[0075]

BEST MODE FOR CARRYING OUT THE INVENTION A typical embodiment of the present invention is as follows.

The plate surface diameter of the Li-Al-based layered double hydroxide particle powder is shown by the average value of the numerical values measured from electron micrographs.

The particle thickness of the Li-Al-based layered double hydroxide particle powder is "X-ray diffractometer RAD-2A (manufactured by Rigaku Denki Co., Ltd.)" (tube: Fe, tube voltage: 40 kV, tube current). : 20mA, Goniometer: Wide-angle goniometer,
Sampling width: 0.010 °, scanning speed: 0.500
° / min, divergence slit: 1 °, scattering slit: 1
, Light receiving slit: 0.30 mm), using Li-A
It is shown by the value calculated using the Scherrer's formula from the diffraction peak curve of the (002) crystal plane of the 1-system layered double hydroxide particles.

The particle powder thus obtained was identified by X-ray diffraction and the diffraction angle 2θ was 5 to 5 using the X-ray diffractometer.
It was measured at 90 °.

The BET specific surface area value is shown by the value measured by the BET method.

[0080] Li-Al-based layered double hydroxide particles the ^{_{[Al a Li b (OH)}} 6] + X - · nH 2 O X -: in the case of representation anion, and n ≧ 0 interlayer a, b , And the content of silicon in the powder were determined by dissolving the powder with an acid and measuring with a “plasma emission spectroscopic analyzer SPS4000 (Seiko Denshi Kogyo KK)”.

The carbon content (% by weight) and the content of the sulfur compound or the sulfate ion when CO ₃ ^{2− was} used as the anion (X ⁻ ) were as follows:
It was measured by EMIA-2200 (manufactured by HORIBA).

The degree of orientation (%) of the Li-Al layered double hydroxide particle powder was evaluated by the following method.

Li-Al System Layered Double Hydroxide Particle Powder 1.
5 g, 1 cc of castor oil and 3.5 g of lacquer are mixed sufficiently to form a paint, which is applied to coated paper with an applicator (GAP 150 μm). With the scattering vector perpendicular to the obtained coating film, a diffraction angle of 2 was obtained using the X-ray diffractometer.
Measurement is performed in the range of θ of 5 to 90 °.

From the obtained X-ray diffraction measurement result,
The orientation degree is calculated by the following formula described in Japanese Patent Laid-Open No. 6-35004.

[0085]

[Equation 1]

Here, I indicates the integrated intensity of the diffraction peak, and subscripts A and R indicate the oriented sample and the non-oriented sample, respectively. ΣI _A 00l and ΣI _R 001 are surface indices (00
2), (004), (006), and (008) show the sum of the diffraction peak intensities of the respective planes, and I _A total and I _R t
total represents the sum of all peak intensities at a diffraction angle 2θ of 5 to 90 °.

The plate surface of the Li-Al layered double hydroxide particles according to the present invention is parallel to the (00l) plane of the 2H type laminated structure. Therefore, the degree of orientation is to evaluate the relative ratio of the reflection intensity of the plane parallel to the (001) plane, and is a relative evaluation of how the plate surface of the plate-like particles in the coating film faces the film surface. It is a thing.

<Embodiment I: Production of Li-Al Layered Double Hydroxide Particle Powder by Production Method of Present Invention 1> CO ₃
^2- ion concentration of 0.96 mol / aqueous sodium carbonate 500ml of l and 18.4Mol / l sodium hydroxide aqueous solution 489ml (pH value = 14.2) and water 50
Mix 0 ml, hold at 60 ° C. and stir in reaction vessel. To this, a mixed solution of 500 ml of 1.0 mol / l lithium sulfate aqueous solution and 1000 ml of 1.0 mol / l aluminum sulfate aqueous solution was added, and 12.48 g of No. 3 water glass was added to make a total amount of 4.0 l. While stirring the reaction vessel, the pH value is 13.8 and the temperature is 1
Aged for 2 hours to form a white precipitate. The white precipitate was filtered, washed with water and then dried to obtain white particle powder.

As a result of identifying this white particle powder by X-ray diffraction, it was confirmed that it was a layered double hydroxide particle powder.

The plate surface diameter of the obtained Li-Al-based layered double hydroxide particles was 0.22 μm, the thickness was 0.0100 μm, the plate ratio was 22.0, the specific surface area was 58.9 m ² / g, and silicon was used. The content was 0.18% by weight and the degree of orientation was 75%.

<Embodiment II: Production of Li—Al-based layered double hydroxide particle powder by the production method of the present invention 2> CO ₃
500 ml of an aqueous solution of sodium carbonate with a ^2- ion concentration of 0.96 mol / l, 402 ml of an aqueous solution of sodium hydroxide of 18.4 mol / l (pH value = 14.2) and 50 water
Mix 0 ml, hold at 60 ° C. and stir in reaction vessel. To this, a mixed solution of 500 ml of 0.8 mol / l lithium sulfate aqueous solution and 1000 ml of 0.8 mol / l aluminum sulfate aqueous solution was added, and the total amount was 3.2 l.
And While stirring the inside of the reaction vessel, the pH value is 13.4,
Aged at 95 ° C. for 8 hours to form a white precipitate. The plate surface diameter of the obtained Li-Al-based layered double hydroxide core particles was 0.3.
0 μm, thickness 0.0114 μm, specific surface area 53.5
m was ² / g. (Primary reaction)

Then, a mixed solution of 125 ml of 0.8 mol / l lithium sulfate aqueous solution and 250 ml of 0.8 mol / l aluminum sulfate aqueous solution was added, and 12.48 g of No. 3 water glass was added to make a total amount of 4.0 l. While agitating the inside of the reaction vessel, the pH value was 11.5 and the mixture was aged at 95 ° C. for 6 hours to form a white precipitate. (Secondary reaction) The ratio of the total molar number of lithium and aluminum added in the secondary reaction to the total molar number of lithium and aluminum added in the primary reaction is 0.25. The white precipitate was filtered, washed with water, and then dried at 60 ° C. to obtain white particle powder.

As a result of identifying this white particle powder by X-ray diffraction, it was confirmed that it was a layered double hydroxide particle powder.

Obtained Li-Al-based layered double hydroxide particles
The powder has an average plate surface diameter of 0.36 μm and a thickness of 0.012.
8 μm, plate ratio 28.1, BET specific surface area value 47.
5m ^Two/ G, silicon content 0.18% by weight, degree of orientation is
It was 85%.

[0095]

The important point in the present invention is the plate ratio (plate surface diameter /
Thickness) 20 to 100, plate surface diameter 0.05 to 2.0 μm
And a Li-Al layered double hydroxide particle powder containing a silicon hydroxide or a silicon oxide, wherein the silicon content is 0.1-2.5 wt% Li-Al. The system layered double hydroxide particle powder has a large plate-like ratio and is excellent in orientation when it is used as a coating film.

The reason why the orientation of the Li-Al-based layered double hydroxide particles according to the present invention when formed into a coating film is excellent is that the powder has a large plate-like ratio. In this case, it is considered that the Li-Al-based layered double hydroxide particle powder is easily oriented.

The plate-like ratio of the Li-Al-based layered double hydroxide particles according to the present invention is large because the anion containing silicon has a Li-Al-based layered structure due to the presence of silicon in the reaction solution. By repeating adsorption and desorption on the C surface (plate surface) of the double hydroxide particles, the plate surface diameter grows in a state in which the crystal growth in the thickness direction of the plate particles is suppressed, so that the plate ratio is improved. It is presumed to do so.

Further, a part of the silicon hydroxide or the silicon oxide adheres to the particle surface of the Li-Al layered double hydroxide particles, so that the Li-Al layered double hydroxide according to the present invention can be obtained. It is considered that the dispersibility of the material particle powder in the resin is improved and the degree of orientation in the coating film is improved.

The method for producing the Li-Al layered double hydroxide particles of the present invention 2 comprises a core particle forming reaction (first reaction) and a core particle growth reaction (second reaction). Therefore, it is possible to easily obtain the Li—Al-based layered double hydroxide particle powder having a large plate surface diameter and a large plate ratio.

[0100]

EXAMPLES Next, examples and comparative examples will be given.

Examples 1 to 3 and Comparative Examples 1 to 3 Li-Al was carried out in the same manner as in Embodiment I except that the concentration of the alkaline aqueous solution, the aging temperature, the aging time and the addition amount of the silicon compound were variously changed. A system layered double hydroxide particle powder was obtained.

The manufacturing conditions at this time are shown in Table 1.
Various properties of the i-Al-based layered double hydroxide particle powder are shown in Table 2. In Comparative Example 3, since the amount of the silicon compound added was large, Al silicate was also formed and a single phase of the Li-Al-based layered double hydroxide could not be obtained.

[0103]

[Table 1]

[0104]

[Table 2]

Examples 4 to 11 and Comparative Examples 4 to 7 Type and concentration of lithium compound, type and concentration of aluminum compound, concentration of sodium carbonate salt, concentration of alkaline aqueous solution, aging temperature, aging time and addition amount of silicon compound. Li-Al-based layered double hydroxide particles were obtained in the same manner as in Embodiment II except that the above was changed variously. Comparative Example 7 is a commercially available Li-Al layered double hydroxide particle powder (plate surface diameter 0.35 μm, thickness 0.0290 μm, plate ratio 12.1, specific surface area 22.6 m ² / g), Mizucarac L (Trade name, manufactured by Mizusawa Chemical Industry Co., Ltd.).

The production conditions of the primary reaction (core particles) at this time are shown in Table 3, the characteristics of the obtained Li-Al-based layered double hydroxide core particles are shown in Table 4, and the production conditions of the secondary reaction are shown. Table 5 shows various properties of the obtained Li-Al-based layered double hydroxide particle powder. In Comparative Example 6, since the addition amount of the silicon compound is large, Al silicate is also formed and Li-Al.
No single phase of the system layered double hydroxide was obtained.

[0107]

[Table 3]

[0108]

[Table 4]

[0109]

[Table 5]

[0110]

[Table 6]

[0111]

The Li-Al layered double hydroxide particles according to the present invention have a large plate ratio and a high degree of orientation, so that they are used as an undercoat paint for automobiles, a rust preventive paint, and a magnetic tape reinforcing agent. Is suitable as

Claims (3)

[Claims] 1. An alkaline aqueous solution containing an anion, an aqueous lithium salt solution and an aluminum compound capable of forming aluminum ions are mixed to form a mixed solution having a pH value in the range of 8 to 14, and the mixed solution is then added to 60 to In the method for producing Li-Al-based layered double hydroxide particles by aging in the temperature range of 105 ° C, 0.1 is calculated as Si with respect to the total number of moles of the lithium and the aluminum.
A method for producing a Li-Al-based layered double hydroxide particle powder, which comprises allowing 10 mol% of a silicon compound to be present during the aging. 2. An alkaline aqueous solution containing an anion, an aqueous lithium salt solution and an aluminum compound capable of forming aluminum ions are mixed to form a mixed solution having a pH value in the range of 10 to 14, and then the mixed solution is added to 60 to Alumina capable of forming core particles of Li-Al-based layered double hydroxide particles by aging in a temperature range of 105 ° C, and then forming an aqueous lithium salt solution and aluminum ions in an aqueous suspension containing the core particles. After adding the compound, the pH value is 8 ~ 1
In the method for producing Li-Al-based layered double hydroxide particles by aging in the range of 4 and the temperature in the range of 60 to 105 ° C, in terms of Si with respect to the total number of moles of the total lithium and the total aluminum. And 0.1 to 10 mol% of a silicon compound are allowed to be present during the aging, to prepare a Li-Al-based layered double hydroxide particle powder. 3. An average plate surface diameter of 0.05 to 2.0 μm, a plate ratio (plate surface diameter / thickness) of 20 to 100, and containing silicon hydroxide or silicon oxide. Li-A
1-based layered double hydroxide particles, wherein the content of the silicon hydroxide or silicon oxide is 0.1 to 2.5% by weight as the silicon content. Particle powder.