Metal pyrophosphate salt, method for producing flaky metal pyrophosphate salt, flaky metal pyrophosphate salt, method for producing metal pyrophosphate porous body, metal pyrophosphate salt porous body, and composite body

Abstract

The present invention realizes a metal pyrophosphate compound having excellent dispersion stability.　For example, this metal pyrophosphate salt is represented by formula (1): (Rn / a+)a[A2-xBxP2O7+n / 2]n-. In formula (1), A includes at least one element selected from Zn, Co, Mn, Cu, Ni, Cd, Cr, and Fe. B includes at least one element selected from Mg, Al, Si, Ti, V, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ta, W, and Bi. R includes hydrogen or an organic amine compound. n satisfies 0<n≤20. a satisfies 0<a≤20. x satisfies 0≤x<2.

Description

Metal pyrophosphate, method for producing flaky metal pyrophosphate, flaky metal pyrophosphate, method for producing porous metal pyrophosphate, porous metal pyrophosphate and composite

[0001] The present invention relates to a metal pyrophosphate, a method for producing flaky metal pyrophosphate, a flaky metal pyrophosphate, a method for producing porous metal pyrophosphate, a porous metal pyrophosphate and a composite.

[0002] A negative thermal expansion material whose lattice volume decreases as temperature rises (has a negative coefficient of thermal expansion), and as an example of such a negative thermal expansion material, zinc magnesium pyrophosphate Zn ２－ｘ Mg ｘ P ２ O ７ is known.

[0003] Japanese Unexamined Patent Publication No. 2024-100562

[0004] Pyrophosphate compound T ｅ Z ｇ P ２ O ７ (T=Zn, Mg, Ti, Ba, Z=organic group, e>0, g≧0) is a material attracting attention as an active material for negative thermal expansion materials and battery materials. When this pyrophosphate compound is used as an insulating film for semiconductor manufacturing, it is often used as a composite material with a resin, and dispersion stability is required for dispersions mixed with a solvent, as well as dispersions mixed with a resin and a solvent. Furthermore, high-frequency insulating films require low dielectric properties and a high-degree of thermal expansion suppression effect. Heretofore, a method for obtaining zinc pyrophosphate compound particles of micron size or larger by sintering zinc oxide and a phosphate at high temperature has been known, but there has been a problem of poor dispersion stability when mixed with a solvent.

[0005] In one aspect, an object of the present invention is to provide a metal pyrophosphate compound excellent in dispersion stability.

[0006] In one embodiment, there is provided a metal pyrophosphate represented by the following formula (1) or (2). (R ｎ／ａ+ ) ａ [A ２－ｘ B ｘ P ２ O ７＋ｎ／２ ｎ－ ​... (1) [In formula (1), A includes at least one element selected from Zn, Co, Mn, Cu, Ni, Cd, Cr, Fe. B includes at least one element selected from Mg, Al, Si, Ti, V, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ta, W, Bi. R includes hydrogen or an organic amine compound. n satisfies 0 < n ≤ 20. a satisfies 0 < a ≤ 20. x satisfies 0 ≤ x < 2.] (Q ｍ／ｂ+ ) ｂ [E １－ｙ G ｙ P ２ O ７ ] ｍ－ ... (2) [In formula (2), E includes at least one element selected from Zn, Co, Mn, Cu, Ni, Cd, Cr, and Fe. G includes at least one element selected from Mg, Al, Si, Ti, V, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ta, W, and Bi. Q includes hydrogen or an organic amine compound. m satisfies 0 < m ≤ 2. b satisfies 0 < b ≤ 2. y satisfies 0 ≤ y < 1.] In another embodiment, a method for producing a flaky metal pyrophosphate using the above-mentioned metal pyrophosphate, a flaky metal pyrophosphate obtained by the method, a method for producing a porous metal pyrophosphate using the flaky metal pyrophosphate, a porous metal pyrophosphate, and a composite containing a flaky metal pyrophosphate or a porous metal pyrophosphate are provided.

[0007] In one respect, it becomes possible to realize metal pyrophosphate compounds with excellent dispersion stability. The above and other objects, features and advantages of the present invention will become apparent from the following description in conjunction with the accompanying drawings illustrating preferred embodiments as examples of the present invention.

[0008] This figure shows the particle size distribution of flaky magnesium zinc pyrophosphate. This figure shows an electron microscope image of magnesium zinc pyrophosphate. This figure shows an electron microscope image of flaky magnesium zinc pyrophosphate. This figure shows an electron microscope image of a porous magnesium zinc pyrophosphate.

[0009] The present invention provides a metal pyrophosphate obtained by exfoliating layered crystals made of metal pyrophosphate, a method for producing the same, and a method for producing a porous metal pyrophosphate. Specifically, the gist of the present invention is a metal pyrophosphate produced from a layered metal pyrophosphate under acidic or alkaline conditions, a method for producing the same, and a method for producing a porous metal pyrophosphate obtained by heating the obtained metal pyrophosphate.

[0010] The inventors of this invention have identified Na as a metal pyrophosphate compound. ２ ZnP ２ O ７ I focused on the system. Na ２ ZnP ２ O ７ , ZnP ２ O ７ It is known to be a compound having a layered crystalline structure in which phases formed by and phases formed by are alternately stacked, and ZnP ２ O ７ We discovered that by exchanging interlayer cations with other cations, the metal pyrophosphate compound can be converted into a form with high dispersion stability in resins and solvents. Specifically, by reacting the metal pyrophosphate compound under acidic or alkaline conditions, we synthesized metal pyrophosphate salts in which the cations were exchanged for protons or organic amine compounds. Furthermore, we found that flaky metal pyrophosphate salts can be formed, and that porous metal pyrophosphate can be produced by heat-treating these flaky metal pyrophosphate salts.

[0011] The metal pyrophosphates of this disclosure are represented by the following formula (1) or (2). (R ｎ／ａ+ ) ａ [A ２－ｘ B ｘ P ２ O ７＋ｎ／２ ] ｎ－... (1) [In formula (1), A includes at least one element selected from Zn, Co, Mn, Cu, Ni, Cd, Cr, Fe. B includes at least one element selected from Mg, Al, Si, Ti, V, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ta, W, Bi. R includes hydrogen or an organic amine compound. n satisfies 0 < n ≤ 20. a satisfies 0 < a ≤ 20. x satisfies 0 ≤ x < 2.] (Q ｍ／ｂ+ ) ｂ [E １－ｙ G ｙ P ２ O ７ ] ｍ－ ... (2) [In formula (2), E contains at least one element selected from Zn, Co, Mn, Cu, Ni, Cd, Cr, and Fe. G contains at least one element selected from Mg, Al, Si, Ti, V, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ta, W, and Bi. Q contains hydrogen or an organic amine compound. m satisfies 0 < m ≤ 2. b satisfies 0 < b ≤ 2. y satisfies 0 ≤ y < 1.] In the metal pyrophosphate represented by the above formula (1) or (2), the volume frequency center particle size (median diameter) measured by a laser diffraction / scattering particle size distribution evaluation device is preferably 30 nm or more and less than 1 μm, more preferably 30 nm or more and less than 800 nm, and even more preferably 30 nm or more and less than 500 nm.

[0012] According to this embodiment, when metal pyrophosphates are dispersed in a base material such as a resin, sedimentation can be suppressed due to the charge of the metal pyrophosphates and the effect of the organic amine compound acting as a counterion, thereby achieving homogeneous dispersion.

[0013] Pyrophosphates are, for example, Na ２ ZnP ２ O ７ Na ２ CoP ２ O ７ Na ２ MnP ２ O ７ Na ２ Cup ２ O ７ Na２ NiP ２ O ７ It is known that many stoichiometric compositions exist, and it has a flexible crystal structure. For this reason, many elements close to Zn on the periodic table are preferred as A and B in formula (1) and E and G in formula (2). For example, Zn, Co, Mn, Cu, Ni, Cd, Cr, Fe, Mg, Al, etc. are preferred as A and B and E and G.

[0014] In formula (1) above, R and in formula (2) above, Q are preferably positively charged protons or organic amine compounds. As the organic amine compound, primary, secondary, or tertiary amines, or quaternary ammonium salts may be used. Specifically, as primary, secondary, or tertiary amines, n-ethylamine (C) ２ H ５ NH ２ ), n-propylamine (C ３ H ９ NH ２ ), 1-amino-2-ethanol (CH ２ NH ２ -CH ２ OH), 1-amino-3-propanol (CH ２ NH ２ -CH ２ -CH ２ Examples include OH, and quaternary ammonium salts include tetrabutylammonium hydroxide ((C)). ４ H ９ ) ４ NOH), tetramethylammonium hydroxide ((CH ３ ) ４ NOH), tetraethylammonium hydroxide ((C ２ H ５ ) ４ NOH), tetrapropylammonium hydroxide ((C ３ H ７ ) ４ Examples include NOH (Nutrient-Based Oxide).

[0015] n in the above formula (1) may satisfy 2≦n≦20. More preferably, n satisfies 2≦n≦16, and still more preferably, n satisfies 2≦n≦8. a in the above formula (1) may satisfy 2≦a≦20. More preferably, a satisfies 2≦a≦16, and still more preferably, a satisfies 2≦a≦8.

[0016] x in the above formula (1) may satisfy 0≦x≦0.8. More preferably, x satisfies 0.05≦x≦0.8. m in the above formula (2) may satisfy 0.1≦m≦2. More preferably, m satisfies 0.5≦m≦2, and still more preferably, m satisfies 1≦m≦2.

[0017] b in the above formula (2) may satisfy 0.1≦b≦2. More preferably, b satisfies 0.5≦b≦2, and still more preferably, b satisfies 1≦b≦2. y in the above formula (2) may satisfy 0≦y≦0.8. More preferably, y satisfies 0.05≦y≦0.8.

[0018] The values of n in the above formula (1) and m in the above formula (2) can be estimated by analyzing water desorbed from the metal pyrophosphate or an organic amine compound. For example, in simultaneous thermogravimetry-differential thermal analysis (TG-DTA), the values of n and m can be estimated from a weight loss rate of 0 to 80% observed in accordance with a temperature change from 30°C to 700°C.

[0019] Another aspect of the present disclosure is a flaky metal pyrophosphate obtained by reacting at least one selected from the group consisting of the metal pyrophosphate represented by the above formula (1) or (2) and a compound represented by the following formula (3) in a liquid medium under acidic or alkaline conditions.

[0020] M ＋ ｐ [X １－ｚ Y ｚ P ２ O ７ ｐ－ ​... (3) In equation (3), X includes at least one element selected from Zn, Co, Mn, Cu, Ni, Cd, Cr, and Fe. Y includes at least one element selected from Mg, Al, Si, Ti, V, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ta, W, and Bi. M includes at least one element selected from Li, Na, K, Rb, and Cs. p satisfies 0 < p ≤ 2. z satisfies 0 ≤ z < 1.

[0021] According to this embodiment, when flake-shaped metal pyrophosphate is dispersed in a base material such as a resin, a more homogeneous dispersion can be achieved. Furthermore, since the median diameter of the flake-shaped metal pyrophosphate is equal to or smaller than the wavelength of visible light (300 nm to 800 nm), the transmittance of visible light can be maintained even when the flake-shaped metal pyrophosphate is incorporated into transparent or translucent materials such as glass or acrylic.

[0022] Here, "flaky" means that the length of the short side of the particle is between 0.1 nm and 100 nm. The length of the short side of the particle can be appropriately changed by modifying the conditions of the manufacturing method described below. The length of the short side of the particle may be 100 nm or less, 90 nm or less, 80 nm or less, 70 nm or less, 60 nm or less, 50 nm or less, 40 nm or less, 30 nm or less, 20 nm or less, 10 nm or less, 1 nm or less, or 0.5 nm or less.

[0023] The acid used to create acidic conditions may be an inorganic acid or an organic acid. Preferred inorganic acids include, for example, hydrochloric acid, nitric acid, and phosphoric acid. Preferred organic acids include, for example, citric acid, oxalic acid, and acetic acid. It is more preferable to use a weak acid such as phosphoric acid, citric acid, oxalic acid, or acetic acid.

[0024] The liquid medium may be water or an organic solvent. Examples of organic solvents that can be used include acetonitrile, methanol, dimethyl sulfoxide, ethanol, 2-propanol, N,N-dimethylformamide, methyl ethyl ketone, 1-butanol, formamide, γ-butyrolactone, 1-methoxypropanol, 2-methoxy-1-methylethyl acetate, cyclopentanone, mesitylene, toluene, etc.

[0025] The flaky metal pyrophosphate may be produced in powder form by drying. Preferred drying methods include vacuum drying, low-temperature vacuum freeze-drying, high-temperature heating drying, microwave drying, and supercritical drying, with vacuum drying and low-temperature vacuum freeze-drying being more preferred.

[0026] A porous metal pyrophosphate can be produced by further heating the flaky metal pyrophosphate of the present disclosure. According to Japanese Patent Publication No. 2958440, it is known that titanium oxide particles having a flaky structure are converted into a porous aggregate when heated, and it is believed that a similar phenomenon occurs when the flaky metal pyrophosphate of the present invention is heated (and thereby forms a porous metal pyrophosphate).

[0027] The heating temperature range for the flake-shaped metal pyrophosphate is 400°C or higher and less than 2000°C, preferably 400°C or higher and less than 1000°C, and more preferably 400°C or higher and less than 800°C. The porous metal pyrophosphate obtained by heating the flake-shaped metal pyrophosphate has a unique structure in which pores ranging from mesopores to macropores have developed over a wide range of pore diameters from 2 nm to 200 nm. A variety of effects can be expected from porous metal pyrophosphate with such characteristics, one of which is the low dielectric properties and high thermal expansion suppression effect required for high-frequency insulating films and the like. In addition, because it has a lower particle density compared to non-porous particles, a more homogeneous dispersion can be achieved when dispersed in a base material such as a resin.

[0028] A further aspect of this disclosure is a porous metal pyrophosphate comprising a metal pyrophosphate represented by the following formula (4). ２－ｑ L ｑ P ２ O７ ... (4) [In formula (4), J contains at least one element selected from Zn, Co, Mn, Cu, Ni, Cd, Cr and Fe. L contains at least one element selected from Mg, Al, Si, Ti, V, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ta, W and Bi. q satisfies 0≦q<2.] The porous metal pyrophosphate represented by formula (4) above can be produced, for example, by mixing a raw material of metal pyrophosphate such as a metal oxide or ammonium dihydrogen phosphate, or metal pyrophosphate particles with a blowing agent, and heating the mixture.

[0029] Here, the blowing agent may be an inorganic blowing agent or an organic blowing agent. As the inorganic blowing agent, for example, hydrogen peroxide solution, ammonium bicarbonate, sodium bicarbonate and the like can be used. As the organic blowing agent, for example, azodicarbonamide, polymer hollow fine particles, polyurethane foam particles, polyethylene foam particles and the like can be used.

[0030] The metal pyrophosphate, flaky metal pyrophosphate and porous metal pyrophosphate of the present disclosure may form a composite comprising one or more of these and a resin. Examples of the resin that can be used include epoxy resins, phenolic resins, fluororesins, acrylic resins, butadiene resins and copolymers thereof, polyarylene ethers, polyarylenes, polycarbonates, polyimides, polyamideimides, polypropylene, polyamides, polyethylene, polyethylene terephthalate, bismaleimide resins, cyanate resins, aromatic polyesters, cycloolefin copolymers, cyclic olefin resins and the like.

[0031] <Examples> Examples will be described below. However, the present invention is not limited to the following examples.

[0032] Zinc magnesium pyrophosphate acid and flaky zinc magnesium pyrophosphate salt were produced by the production method of the present disclosure. Here, zinc magnesium pyrophosphate acid is (R of formula (1) above ｎ／ａ+ ) ａ [A ２－ｘ B ｘ P ２ O ７＋ｎ／２] ｎ－ In the above equation (2), R=H, A=Zn, B=Mg, n=8, a=8, x=0.4, or (Q ｍ／ｂ+ ) ｂ [E １－ｙ G ｙ P ２ O ７ ] ｍ－ In this example, Q=H, E=Zn, G=Mg, m=2, b=2, and x=0.2. The flaky magnesium zinc pyrophosphate salt is (R) of formula (1) above. ｎ／ａ+ ) ａ [A ２－ｘ B ｘ P ２ O ７＋ｎ／２ ] ｎ－ In this case, R = tetrabutylammonium ((C ４ H ９ ) ４ The parameters were set as follows: N), A=Zn, B=Mg, n=8, a=8, x=0.4. In addition, a porous metal pyrophosphate, a composite containing a metal pyrophosphate salt and a resin, and a composite containing a porous metal pyrophosphate and a resin were produced.

[0033] [Synthesis Example 1] Preparation of magnesium sodium zinc pyrophosphate Powder of magnesium sodium zinc pyrophosphate was prepared by a solid-phase reaction method. Sodium dihydrogen phosphate (NaH) was used as a raw material. ２ PO ４ By mixing 99% pure zinc oxide (ZnO, 99.9% purity) and magnesium oxide (MgO, 99.9% purity) powders in a molar ratio of 10:4:1 using an alumina mortar and pestle, and then calcining the mixture in a platinum crucible at 720°C in air for 48 hours, magnesium sodium zinc pyrophosphate (Na) is produced. ２ Zn ０．８ Mg ０．２ P ２ O ７ ) was synthesized.

[0034] [Example 1] Preparation of zinc magnesium pyrophosphate 10 g of sodium zinc magnesium pyrophosphate powder obtained in Synthesis Example 1 was stirred in a 1 N citric acid aqueous solution for 2 days, then filtered and air-dried to obtain zinc magnesium pyrophosphate (H ８ Zn １．６ Mg０．４ P ２ O １１ ) was obtained.

[0035] [Example 2] Preparation of magnesium zinc pyrophosphate 10 g of sodium magnesium zinc pyrophosphate powder obtained in Synthesis Example 1 was stirred in a 1 N citrate ethanol solution for 2 days, then filtered and air-dried to obtain magnesium zinc pyrophosphate (H ２ Zn ０．８ Mg ０．２ P ２ O ７ ) was obtained.

[0036] [Example 3] Preparation of flaky magnesium zinc pyrophosphate salt 4 g of magnesium zinc pyrophosphate powder obtained in Example 1 was added to 1 L of tetrabutylammonium hydroxide aqueous solution (concentration 0.1 mol / L), stirred for 4 days, and the solvent was removed by distillation at 60°C under reduced pressure to obtain flaky magnesium zinc pyrophosphate salt (((C ４ H ９ ) ４ N) ８ Zn １．６ Mg ０．４ P ２ O １１ ) was prepared.

[0037] [Example 4] Preparation of porous magnesium zinc pyrophosphate 1 g of the flaky magnesium zinc pyrophosphate salt obtained in Example 3 was dispersed in 0.1 L of ultrapure water, and a 1 N aqueous citric acid solution was added and stirred for 30 minutes to re-aggregate the magnesium zinc pyrophosphate salt. After that, the mixture was filtered and dried to obtain magnesium zinc pyrophosphate powder. Next, this powder was heated in air at 550°C for 1 hour to obtain a porous magnesium zinc pyrophosphate material.

[0038] [Example 5] Preparation of porous material containing magnesium sodium zinc pyrophosphate A porous material powder containing magnesium sodium zinc pyrophosphate was prepared by a solid-phase reaction method. Sodium dihydrogen phosphate (NaH) was used as a raw material. ２ PO ４ , 99% purity zinc oxide (ZnO), 99.9% purity magnesium oxide (MgO), 99.9% purity ammonium bicarbonate (NH ４ HCO ３A porous magnesium sodium zinc pyrophosphate was synthesized by mixing a 99% pure powder in a molar ratio of 10:4:1:1 using an alumina mortar and pestle, and then calcining the mixture in a platinum crucible at 720°C in air for 48 hours.

[0039] [Example 6] Composites containing flaky magnesium zinc pyrophosphate and resin, and composites containing porous magnesium zinc pyrophosphate and resin. Powder of the flaky magnesium zinc pyrophosphate or porous magnesium zinc pyrophosphate, modified polyphenylene ether at both ends, dicumyl peroxide, and 2-butanone were weighed into vials to obtain a solid content ratio of 50:50:2.5:100, and then mixed with a mix rotor to prepare a crosslinkable composition varnish with a solid content of 50% by weight. The obtained crosslinkable composition was applied to copper foil (CF-T49A-DS-HD2 (Fukuda Metal Co., Ltd.), matte surface) using a baker applicator (gap 100 μm), dried at 100°C for 5 minutes, and then fired in nitrogen at 200°C for 2 hours to form a cured film of about 50 μm on the copper foil. The obtained copper foil laminate was immersed in a 40% by mass iron chloride solution to remove the copper foil, washed with water, and oven-dried at 80°C for 30 minutes. This isolated the cured film. Using this method, a composite containing flaky magnesium zinc pyrophosphate and resin, and a composite containing porous magnesium zinc pyrophosphate and resin were prepared as cured films.

[0040] [Comparative Example 1] Preparation of magnesium zinc pyrophosphate Magnesium zinc pyrophosphate powder was prepared by a solid-phase reaction method. Ammonium dihydrogen phosphate (NH4) was used as a raw material. ４ H ２ PO ４ Powders of 99% pure zinc oxide (ZnO, 99.9% purity) and magnesium oxide (MgO, 99.9% purity) were mixed in a molar ratio of 5:4:1 using an alumina mortar and pestle, and then calcined in a platinum crucible at a temperature of 800°C to 850°C in air for 2 to 6 hours. After calcination, the mixture was removed, mixed again using an alumina mortar and pestle, and then calcined in a platinum crucible at a temperature of 850°C to 900°C in air for 2 to 10 hours to obtain granular magnesium zinc pyrophosphate (Zn１．６ Mg ０．４ P ２ O ７ ) was synthesized.

[0041] [Evaluation 1] Particle size measurement of magnesium zinc pyrophosphate The particle size of the flaky magnesium zinc pyrophosphate of Example 3 was measured using a laser diffraction / scattering particle size evaluation device (MT3300EXII, Microtrac). Figure 1 shows the particle size distribution of the flaky magnesium zinc pyrophosphate of Example 3. The volume frequency median particle size (median diameter) D of the flaky magnesium zinc pyrophosphate of Example 3 shown in Figure 1 is ５０ = 0.45 μm, D ９０ The value was 1.29 μm.

[0042] [Evaluation 2] Shape evaluation of zinc magnesium pyrophosphate, flaky zinc magnesium pyrophosphate salt, and porous zinc magnesium pyrophosphate The shapes of zinc magnesium pyrophosphate from Example 1, flaky zinc magnesium pyrophosphate from Example 3, and porous zinc magnesium pyrophosphate from Example 4 were evaluated using a scanning electron microscope (Phenom ProX, Thermo Scientific).

[0043] Figure 2 shows an electron microscope image of magnesium zinc pyrophosphate from Example 1. The magnesium zinc pyrophosphate 1 from Example 1 shown in Figure 2 is in the form of thin flakes with a short side length of 0.1 nm or more and less than 100 nm.

[0044] Figure 3 shows an electron microscope image of the flaky magnesium zinc pyrophosphate salt of Example 3. The flaky magnesium zinc pyrophosphate salt 2 of Example 3 shown in Figure 3 is in a flaky form, having been peeled to a thickness below the lower limit of the resolution of the scanning electron microscope used, so the particle shape is not observed.

[0045] Figure 4 shows an electron microscope image of the magnesium zinc pyrophosphate porous material of Example 4. The magnesium zinc pyrophosphate porous material of Example 4 shown in Figure 4 has a porous structure with countless pores between 2 nm and 100 nm in size.

[0046] [Evaluation 3] Evaluation of Dispersion Stability of Magnesium Zinc Pyrophosphate Compounds The dispersion stability of magnesium zinc pyrophosphate from Example 1, magnesium zinc pyrophosphate from Example 2, flaky magnesium zinc pyrophosphate salt from Example 3, porous magnesium zinc pyrophosphate from Example 4, and magnesium zinc pyrophosphate from Comparative Example 1 was evaluated. Dispersion stability was evaluated by adding 0.01 g of each magnesium zinc pyrophosphate compound from Examples 1-4 and Comparative Example 1 to 1 mL of methyl ethyl ketone, stirring at room temperature for 1 hour, and then standing at room temperature for 1 hour, and visually evaluating whether or not sedimentation occurred. The results are shown in Table 1.

[0047]

[0048] As shown in Table 1, while sedimentation was observed in Comparative Example 1 (magnesium zinc pyrophosphate), no sedimentation was observed in Example 1 (magnesium zinc pyrophosphate acid), Example 2 (magnesium zinc pyrophosphate acid), Example 3 (flaky magnesium zinc pyrophosphate salt), or Example 4 (porous magnesium zinc pyrophosphate). It was confirmed that each of the magnesium zinc pyrophosphate compounds in Examples 1-4 can achieve high dispersion stability.

[0049] The above merely illustrates the principle of the present invention. Furthermore, numerous modifications and alterations are possible for those skilled in the art, and the present invention is not limited to the exact configurations and applications shown and described above. All corresponding modifications and equivalents are considered to be within the scope of the present invention as defined by the appended claims and equivalents.

[0050] 1. Zinc magnesium pyrophosphate 2. Flaked zinc magnesium pyrophosphate salt 3. Porous zinc magnesium pyrophosphate

Claims

1. A metal pyrophosphate represented by the following formula (1) or (2). (R ｎ／ａ+ ) ａ [A ２－ｘ B ｘ P ２ O ７＋ｎ／２ ｎ－ ...(1) In formula (1), A contains at least one element selected from the group consisting of Zn, Co, Mn, Cu, Ni, Cd, Cr and Fe. B contains at least one element selected from the group consisting of Mg, Al, Si, Ti, V, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ta, W and Bi. R contains hydrogen or an organic amine compound. n satisfies 0 < n ≤ 20. a satisfies 0 < a ≤ 20. x satisfies 0 ≤ x < 2. (Q ｍ／ｂ+ ) ｂ [E １－ｙ G ｙ P ２ O ７ ｍ－ ...(2) In formula (2), E contains at least one element selected from the group consisting of Zn, Co, Mn, Cu, Ni, Cd, Cr and Fe. G contains at least one element selected from the group consisting of Mg, Al, Si, Ti, V, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ta, W and Bi. Q contains hydrogen or an organic amine compound. m satisfies 0 < m ≤ 2. b satisfies 0 < b ≤ 2. y satisfies 0 ≤ y < 1.]​​ 2. The metal pyrophosphate salt according to claim 1, wherein in formula (1) above, A = Zn and a = n.

3. The metal pyrophosphate according to claim 1, wherein the volume frequency central particle size (median diameter) measured by a laser diffraction / scattering particle size distribution evaluation device is 30 nm or more and less than 1 μm.

4. A method for producing a flaky metal pyrophosphate, comprising reacting the metal pyrophosphate described in claim 1, or at least one compound selected from the group represented by the following formula (3), in a liquid medium under acidic or alkaline conditions to obtain a flaky metal pyrophosphate. ＋ ｐ [X １－ｚ Y ｚ P ２ O ７ ] ｐ－ ... (3) [In formula (3), X includes at least one element selected from Zn, Co, Mn, Cu, Ni, Cd, Cr, and Fe. Y includes at least one element selected from Mg, Al, Si, Ti, V, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ta, W, and Bi. M includes at least one element selected from Li, Na, K, Rb, and Cs. p satisfies 0 < p ≤ 2. z satisfies 0 ≤ z < 1.] 5. A flaky metal pyrophosphate obtained by the manufacturing method described in claim 4, wherein the thickness of the flaky metal pyrophosphate is 0.1 nm or more and 100 nm or less.

6. A method for producing a porous metal pyrophosphate, comprising heating a flake-shaped metal pyrophosphate obtained by the manufacturing method described in claim 4 in a temperature range of 400°C or more and less than 2000°C to obtain a porous metal pyrophosphate containing metal pyrophosphate.

7. A porous metal pyrophosphate containing metal pyrophosphate represented by the following formula (4). J ２－ｑ L ｑ P ２ O ７ ... (4) [In formula (4), J includes at least one element selected from Zn, Co, Mn, Cu, Ni, Cd, Cr, and Fe. L includes at least one element selected from Mg, Al, Si, Ti, V, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ta, W, and Bi. q satisfies 0 ≤ q < 2.] 8. A composite comprising the flaky metal pyrophosphate described in claim 5 and a resin.

9. A composite comprising a metal pyrophosphate porous body obtained by the manufacturing method described in claim 6 or the metal pyrophosphate porous body described in claim 7, and a resin.

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