JP2023038905A - Surface-modified particles and production method thereof - Google Patents

Abstract

To provide means for attaining the long-term presence of hydrogen peroxide directly on surfaces of solid base particles.SOLUTION: The surface-modified particles comprise base particles and hydrogen peroxide and phosphorus oxo acid that are present on surfaces of the base particles.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to particles in which hydrogen peroxide is present on the surface of substrate particles and a method for producing the same.

Due to their oxidizing properties, peroxides are widely used as oxidizing agents, bleaching agents, disinfectants, and the like. In particular, hydrogen peroxide decomposes into oxygen and water, so it has little environmental load. In addition, since hydrogen peroxide is not only a solution, but is also easy to handle during use, hydrogen peroxide is added to various compounds, and it is widely used as a solid hydrogen peroxide adduct. is percarbonated, etc.

These solid hydrogen peroxide adducts are often moisture-labile and readily decompose in the presence of moisture, releasing oxygen. There have been proposed methods of stabilizing by coating with various substances (see, for example, Patent Documents 1 and 2).

Japanese Patent Publication No. 2011-506256 Japanese Patent Publication No. 2009-544556

Due to the properties of solid hydrogen peroxide as described above, even if hydrogen peroxide is allowed to exist directly on the surface of the solid, the hydrogen peroxide on the surface of the solid decomposes over time. Conventionally, there has been no known method of allowing hydrogen peroxide to exist directly on the surface of solid particles for a long period of time.

Here, if hydrogen peroxide can be allowed to exist directly on the surface of the solid particles for a long period of time, the surface of the solid particles can be modified. In addition, antibacterial, antiviral, and deodorant effects can also be expected.

Accordingly, an object of the present invention is to provide means for allowing hydrogen peroxide to exist directly on the surface of solid substrate particles for a long period of time.

The present inventors have made intensive studies in view of the above-mentioned circumstances, and as a result, the base particles are brought into contact with hydrogen peroxide and phosphorus oxoacid, and the surface of the base particles is coated with hydrogen peroxide and phosphorus oxoacid. The present inventors have found that hydrogen peroxide can be directly present on the surface of substrate particles for a long period of time by allowing to exist, and have completed the present invention.

That is, the first invention provided by the present invention is a surface-modified particle comprising a substrate particle and an oxoacid of hydrogen peroxide and phosphorus existing on the surface of the substrate particle. is.

The second invention to be provided by the present invention is a surface-modified material comprising a contacting step of contacting base particles with hydrogen peroxide and phosphorus oxoacid to obtain surface-modified particles. It is a method for producing fine particles.

According to the present invention, it is possible to provide surface-modified particles in which hydrogen peroxide exists directly on the surface of substrate particles for a long period of time.

The present invention will be described below based on its preferred embodiments.
The surface-modified particles of the present invention are surface-modified particles comprising a substrate particle and hydrogen peroxide and phosphorus oxoacid present on the particle surface of the substrate particle. In the surface-modified particles of the present invention, hydrogen peroxide exists directly on the surface of the substrate particles. In the present invention, "hydrogen peroxide is present directly on the surface of the substrate particles" means that the hydrogen peroxide present on the surface of the substrate particles is applied to a stabilizing film or the like. It refers to existing on the substrate particle surface without being coated with. The presence of hydrogen peroxide directly on the surface of the substrate particles without being coated with a stabilizing film can be confirmed by, for example, elution of hydrogen peroxide in a water elution test described later. can be done.

The substrate particles for the surface-modified particles of the present invention are objects to which hydrogen peroxide and phosphorus oxoacid are present on the particle surface. That is, the base particles for the surface-modified particles of the present invention are particles that are brought into contact with hydrogen peroxide and phosphorus oxoacid during the production of the surface-modified particles of the present invention.

The substrate particles are not particularly limited, and do not react with hydrogen peroxide present on the particle surface to promote decomposition of hydrogen peroxide, and hydrogen peroxide and phosphorus oxoacid are present on the particle surface. can exist.

Examples of substrate particles include inorganic compound particles, organic compound particles, inorganic-organic composites, and the like.

Examples of substrate particles made of an inorganic compound include zirconium phosphate tungstate particles represented by the following general formula (1) (hereinafter also referred to as "ZWP particles").
_Zrx ( _WO4 ) _y ( _PO4 ) _z (1)
(Wherein, x is 1.7 ≤ x ≤ 2.3, preferably 1.8 ≤ x ≤ 2.2, y is 0.85 ≤ y ≤ 1.15, preferably 0.90 ≤ y≦1.10, and z is 1.7≦z≦2.3, preferably 1.8≦z≦2.2.)

The ZWP particles related to the substrate particles contain elements other than P, W, Zr and O, which are elements contained in the zirconium phosphate tungstate represented by the general formula (1) (hereinafter referred to as "subcomponents (also referred to as "element") may be contained.

Examples of subcomponent elements include alkali metal elements such as Li, Na and K, alkaline earth metal elements such as Mg, Ca, Sr and Ba, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Transition metal elements such as Y, Nb, Mo, Ag, Hf and Ta; rare earth elements such as La, Ce, Nd, Sm, Eu, Tb, Dy, Ho and Yb; Al, Zn, Ga, Cd, In and Sn , other metal elements other than transition metals such as Pb and Bi, metalloid elements such as B, Si, Ge, Sb and Te, non-metal elements such as S, halogen elements such as F, Cl, Br and I, etc. mentioned. One or more of these elements may be contained in the ZWP particles.

The content of subcomponent elements in the ZWP particles is preferably 0.1 to 3.0% by mass, more preferably 0.2 to 2.0% by mass, based on the ZWP particles. When two or more subcomponent elements are included, the content of the subcomponent elements is calculated based on the total mass of the subcomponent elements. The content of subcomponent elements is measured by a powder press method, a molten glass bead method, or the like, using a measuring device such as a fluorescent X-ray analyzer.

When the ZWP particles contain both Mg and Al as subcomponent elements, the content of the Al element in the ZWP particles is preferably 100 to 6000 mass ppm, more preferably 1000 to 5000 mass ppm, relative to the substrate particles. is. Also, the content of the Mg element in the ZWP particles is preferably 0.10 to 3.0% by mass, more preferably 0.22 to 2.0% by mass, relative to the substrate particles.

ZWP particles are obtained by reacting a zirconium source, a tungsten source, a phosphorus source and, if necessary, a subcomponent element source. The method for producing the substrate particles is not particularly limited. For example, (i) a method of mixing a reaction accelerator such as zirconium oxoate of phosphorus, tungsten oxide and MgO in a wet ball mill and then firing the resulting mixture ( For example, see JP-A-2005-35840), (ii) a zirconium source such as zirconium chloride, a tungsten source such as ammonium tungstate, and a phosphorus source such as ammonium oxoate of phosphorus are wet-mixed, and then the resulting mixture is A method of firing (see, for example, JP-A-2015-10006), (iii) a method of firing a mixture containing zirconium oxide, tungsten oxide, and ammonium dihydrogen oxoate of phosphorus (for example, Materials Research Bulletin, 44 (2009) , p.2045-2049), (iv) calcining a mixture of a tungsten compound, an amorphous compound containing phosphorus and zirconium, and optionally added auxiliary component element sources as a reaction precursor. (See, for example, International Publication No. 2017/061402 pamphlet).

Other substrate particles made of inorganic compounds include silica, porous silica, alumina, titanium oxide, zirconium oxide, tungsten oxide, Cu _2-x Zn _x V ₂ O ₇ (where x is 0<x<2). ), β-eucryptite, zirconium tungstate (ZrW ₂ O ₈ ), bismuth-nickel-iron oxide, M _{x Sry Baz} Zn ₂ Si ₂ O ₇ (M is either Na or Ca). or one or more, x + y + z = 1, 0 < x ≤ 0.5, 0.3 < z < 1.0), zirconium phosphate, aluminum titanate, cordierite, glass, metal carbide, metal nitride, etc. is mentioned.

Substrate particles made of organic compounds include granular organic polymers such as natural fibers, natural resins, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polybutene, polyamide, polyacrylate, polyacrylonitrile, polyacetal, ionomer, Thermoplastic resins such as polyesters, alkyd resins, phenolic resins, urea resins, benzoguanamine resins, melamine resins, xylene resins, silicone resins, epoxy resins, diallyl phthalate resins, etc., may be used alone, You may use it in combination of 2 or more types.

Examples of substrate particles composed of inorganic-organic composites include styrene-silica composite resins, acrylic-silica composite resins, crosslinked alkoxylyl polymer-acrylic resins, polyorganosiloxane-silica, and the like.

The average particle size of the substrate particles is preferably 0.02-50 μm, particularly preferably 0.1-30 μm. In the present invention, the average particle size is D50 determined by a laser diffraction scattering method, and refers to a particle size of cumulative 50% (D50) determined by volume frequency particle size distribution measurement measured by a laser diffraction scattering method.

The BET specific surface area of the substrate particles is preferably 0.1-50 m ² /g, particularly preferably 0.1-20 m ² /g.

The particle shape of the substrate particles is not particularly limited, and may be, for example, spherical, granular, plate-like, scale-like, whisker-like, rod-like, filament-like, irregular crushed stone-like having one or more ridges ( Hereinafter, this is also referred to as “crushed”), or a combination thereof.

In the surface-modified particles of the present invention, hydrogen peroxide is present on the surface of the substrate particles.

In the surface-modified particles of the present invention, the amount of hydrogen peroxide present is 0.01 to 15.0 parts by mass, preferably 0.03 to 10.0 parts by mass, relative to 100.0 parts by mass of the base particles. be. When the amount of hydrogen peroxide present in the surface-modified particles of the present invention is within the above range, the surface of the substrate particles is efficiently coated with hydrogen peroxide.

In the surface-modified particles of the present invention, the hydrogen peroxide present on the surface is contained in the filtrate after filtration in the water elution test described later after being left in a sealed container at room temperature (25 ° C.) for 20 days or more. Hydrogen peroxide is preferably detected with a hydrogen peroxide test paper (manufactured by Merck & Co., product name Quantofix Peroxide 25) in that hydrogen peroxide can be stably present on the particle surface.

In the surface-modified particles of the present invention, hydrogen peroxide and phosphorus oxoacid are present on the surface of the substrate particles. The presence of hydrogen peroxide together with the phosphorus oxoacid stabilizes the hydrogen peroxide on the surface of the base material particle by interacting with the phosphorus oxoacid. , hydrogen peroxide can exist for a long time on the surface of the substrate particles.

A phosphorus oxoacid refers to a compound having a structure in which a hydroxyl group (--OH) and an oxy group (=O) are bonded to a phosphorus atom. Phosphorus oxoacids include phosphoric acid (H ₃ PO ₄ ), phosphonic acid (H ₃ PO ₃ ), phosphinic acid (H ₃ PO ₂ ), pyrophosphoric acid (H ₄ P ₂ O ₇ ), polyphosphoric acid, and the like. be done. Among these, phosphoric acid is preferable as the phosphorus oxoacid because it is easy to handle and available at low cost.

In the surface-modified particles of the present invention, the amount of phosphorus oxoacid present is 0.005 to 20.0 parts by mass, preferably 0.02 to 18.0 parts by mass, with respect to 100.0 parts by mass of the substrate particles. is. When the abundance of the phosphorus oxoacid in the surface-modified particles of the present invention is within the above range, the surface of the substrate particles is efficiently coated with the phosphorus oxoacid.

Regarding the abundance ratio of hydrogen peroxide and phosphorus oxoacid in the surface-modified particles of the present invention, 10.0 to 200.0 parts by weight of phosphorus oxoacid per 100.0 parts by weight of hydrogen peroxide, It is preferably 20.0 to 180.0 parts by mass. When the abundance ratio of hydrogen peroxide and phosphorus oxoacid is within the above range, the stability of the hydrogen peroxide solution on the surface of the substrate particles is enhanced.

Surface-modified particles of the present invention include contact products of substrate particles with hydrogen peroxide and phosphorus oxoacids.

The method for contacting the substrate particles with hydrogen peroxide and phosphorus oxoacid is not particularly limited, and for example, (a) a solution containing hydrogen peroxide and a solution containing phosphorus oxoacid are brought into contact with each other. (b) a method of contacting the base particles with a solution containing hydrogen peroxide and phosphorus oxoacid; and the like.

In a water elution test, the hydrogen peroxide elution concentration of the surface-modified particles of the present invention is preferably 0.5 to 10 mass ppm.

In addition, in this invention, a water elution test is performed by the following method. First, 4.0 g of the surface-modified particles of the present invention are added to 10.0 mL of pure water, stirred and mixed at room temperature (25° C.) for 1 minute, and then allowed to stand at room temperature (25° C.). Then, after 20 hours, the supernatant was filtered through a membrane filter with a diameter of 0.5 μm, and the obtained filtrate was analyzed with a hydrogen peroxide test paper (manufactured by Merck, product name: Quantofix Peroxide 25), and the peroxide of the filtrate was analyzed. Measure the hydrogen concentration. The hydrogen peroxide concentration of the filtrate was evaluated by comparing it with a color sample in which the hydrogen peroxide concentration was changed at intervals of 0.5 mass ppm, 2 mass ppm, 5 mass ppm, 10 mass ppm and 25 mass ppm. done.

In the surface-modified particles of the present invention, hydrogen peroxide and phosphorus oxoacid form various bonds with compounds on the surface of the substrate particles and are present on the particle surfaces. The bonding between the hydrogen peroxide and the oxoacid of phosphorus and the surface of the substrate particles may be hydrogen bonding, ionic bonding, or coordination bonding. In the surface-modified particles of the present invention, the hydrogen peroxide is stabilized by the phosphorus oxoacid due to the interaction between the hydrogen peroxide and the phosphorus oxoacid, and the hydrogen peroxide is stabilized on the surface of the substrate particle. state can exist.

Next, the method for producing the surface-modified particles of the present invention will be explained.
The method for producing surface-modified particles of the present invention comprises a contacting step of bringing base particles into contact with hydrogen peroxide and phosphorus oxoacid to obtain surface-modified particles. manufacturing method.

The contacting step in the method for producing surface-modified particles of the present invention is a step of bringing the base particles into contact with hydrogen peroxide and phosphorus oxoacid. The substrate particles and phosphorus oxoacid in the contacting step are the same as the substrate particles and phosphorus oxoacid in the surface-modified particles of the present invention.

In the contacting step, the method of bringing hydrogen peroxide and phosphorus oxoacid into contact with the substrate particles is not particularly limited. and (b) contacting the substrate particles with a solution containing hydrogen peroxide and phosphorus oxoacid. Among these, the method (b) is preferable because the process can be simplified.

As the method of (a), (a1) the substrate particles are first brought into contact with a solution containing hydrogen peroxide, the contact product between the substrate particles and hydrogen peroxide is recovered, and then the recovered substrate is A method of contacting a solution containing a phosphorus oxoacid with a contact product of material particles and a hydrogen peroxide solution, (a2) first contacting a solution containing a phosphorus oxoacid with the base material particles, and then contacting the base material (a3) a method of contacting a solution containing hydrogen peroxide with a contact product of the particles and the phosphorus oxoacid, and then contacting the recovered contact product of the base particles with the phosphorus oxoacid; A method of first contacting a solution containing hydrogen peroxide and then contacting the contact product of the base particles and the hydrogen peroxide solution with the solution containing the oxoacid of phosphorus without recovering the contact product. (a4) After contacting the substrate particles with a solution containing the phosphorus oxoacid first, the contact product of the substrate particles and the phosphorus oxoacid is then subjected to peroxide without recovering the contact product. A method of contacting a solution containing hydrogen can be mentioned.

Hydrogen peroxide and phosphorus oxoacid used in the contact step are not particularly limited as long as they are industrially available. Hydrogen peroxide and phosphorus oxoacids may also be used as aqueous solutions.

The solution containing hydrogen peroxide and phosphorus oxoacid according to the method (b) is an aqueous solution in which hydrogen peroxide and phosphorus oxoacid are dissolved in a water solvent. The water solvent may be water alone or a mixed solvent of water and a hydrophilic solvent.

The content of hydrogen peroxide in the solution containing hydrogen peroxide and phosphorus oxoacid according to the method (b) is preferably 10.0 to 50.0% by mass, particularly preferably 20.0 to 40.0. % by mass. When the content of hydrogen peroxide in the solution containing hydrogen peroxide and the oxoacid of phosphorus is within the above range, it is preferable in terms of good workability and efficient contact treatment.

The content of the phosphorus oxoacid in the solution containing hydrogen peroxide and the phosphorus oxoacid according to the method (b) is preferably 1.0 to 40.0% by mass, particularly preferably 5.0 to 30.0% by mass. It is 0% by mass. When the content of the phosphorus oxoacid in the solution containing hydrogen peroxide and the phosphorus oxoacid is within the above range, it is preferable in terms of good workability and efficient contact treatment.

The content ratio of hydrogen peroxide and phosphorus oxoacid in the solution containing hydrogen peroxide and phosphorus oxoacid according to the method (b) is as follows: It is preferably 70.0 to 130.0 parts by mass, particularly preferably 80.0 to 120.0 parts by mass. When the content ratio of hydrogen peroxide and phosphorus oxoacid in the solution containing hydrogen peroxide and phosphorus oxoacid is within the above range, it is preferable in terms of good workability and efficient contact treatment. .

In the method (b), the method of contacting the substrate particles with a solution containing hydrogen peroxide and a phosphorus oxoacid includes, for example, a solution containing the substrate particles and hydrogen peroxide and a phosphorus oxoacid. and a method of mixing.

In the method (b), when the solution containing hydrogen peroxide and phosphorus oxoacid is brought into contact with the base particles, the amount ratio of the base particles and hydrogen peroxide is 100.0 parts by mass of the base particles. Hydrogen peroxide is preferably 0.01 to 1.5 parts by mass, particularly preferably 0.03 to 1.0 parts by mass. When the amount ratio of the substrate particles and hydrogen peroxide is within the above range, the surfaces of the substrate particles are efficiently coated with hydrogen peroxide. In addition, in the amount ratio of the substrate particles and hydrogen peroxide, the amount of hydrogen peroxide does not refer to the amount of the hydrogen peroxide solution, but to the amount of hydrogen peroxide itself.

In the method (b), the amount ratio of the base particles and the phosphorus oxoacid when the base particles are brought into contact with the solution containing hydrogen peroxide and the phosphorus oxoacid is 100.0 parts by mass of the base particles. On the other hand, the phosphorus oxoacid is preferably 0.005 to 2.0 parts by weight, particularly preferably 0.02 to 1.8 parts by weight. When the amount ratio of the substrate particles and the phosphorus oxoacid is within the above range, the surfaces of the substrate particles are efficiently coated with the phosphorus oxoacid. In the quantitative ratio of the substrate particles to the hydrogen peroxide, the amount of the phosphorus oxoacid does not refer to the amount of the solution of the phosphorus oxoacid, but to the amount of the phosphorus oxoacid itself.

In the method (b), a solution containing hydrogen peroxide and phosphorus oxoacid is added to 100.0 parts by weight of the base particles, preferably 0.01 to 2.5 parts by weight, particularly preferably 0.01 part by weight. It is preferable to mix up to 2.0 parts by mass because it is possible to perform the contact treatment efficiently with good workability, and it is possible to use the product after the contact treatment as it is without the need to perform a drying treatment. .

The solution containing hydrogen peroxide according to method (a) is an aqueous solution in which hydrogen peroxide is dissolved in an aqueous solvent, and the solution containing phosphorus oxoacid is an aqueous solution in which phosphorus oxoacid is dissolved in an aqueous solvent. is. The water solvent may be water alone or a mixed solvent of water and a hydrophilic solvent.

The content of hydrogen peroxide in the solution containing hydrogen peroxide according to method (a) is preferably 10.0 to 50.0% by mass, particularly preferably 20.0 to 40.0% by mass. When the content of hydrogen peroxide in the solution containing hydrogen peroxide is within the above range, it is preferable in terms of good workability and efficient contact treatment.

The content of the phosphorus oxoacid in the solution containing the phosphorus oxoacid according to the method (a) is preferably 1.0 to 40.0% by mass, particularly preferably 5.0 to 30.0% by mass. be. When the content of the phosphorus oxoacid in the solution containing the phosphorus oxoacid is within the above range, it is preferable in terms of good workability and efficient contact treatment.

The ratio of the hydrogen peroxide in the solution containing hydrogen peroxide and the phosphorus oxoacid in the solution containing phosphorus oxoacid according to the method (a) is, per 100.0 parts by mass of the phosphorus oxoacid, Hydrogen is preferably 70.0 to 130.0 parts by weight, particularly preferably 80.0 to 120.0 parts by weight. When the ratio of the hydrogen peroxide in the solution containing hydrogen peroxide and the oxoacid of phosphorus in the solution containing the oxoacid of phosphorus is within the above range, the contact treatment can be performed efficiently with good workability. point is preferable.

In the method (a), the method of contacting the substrate particles with a solution containing hydrogen peroxide or a solution containing phosphorus oxoacid includes, for example, substrate particles and a solution containing hydrogen peroxide or phosphorus oxoacid and a method of mixing a solution containing an acid.

In the method (a), when the solution containing hydrogen peroxide is brought into contact with the base particles, the amount ratio of the base particles and hydrogen peroxide is such that hydrogen peroxide is added to 100.0 parts by mass of the base particles. , preferably 0.01 to 1.5 parts by mass, particularly preferably 0.03 to 1.0 parts by mass. When the amount ratio of the substrate particles and hydrogen peroxide is within the above range, the surfaces of the substrate particles are efficiently coated with hydrogen peroxide. In addition, in the amount ratio of the substrate particles and hydrogen peroxide, the amount of hydrogen peroxide does not refer to the amount of the hydrogen peroxide solution, but to the amount of hydrogen peroxide itself.

In the method (a), the amount ratio of the base particles and the phosphorus oxoacid when the solution containing the phosphorus oxoacid is brought into contact with the base particles is the amount of phosphorus with respect to 100.0 parts by mass of the base particles. The oxoacid is preferably 0.005 to 2.0 parts by weight, particularly preferably 0.02 to 1.8 parts by weight. When the amount ratio of the substrate particles and the phosphorus oxoacid is within the above range, the surfaces of the substrate particles are efficiently coated with the phosphorus oxoacid. In the quantitative ratio of the substrate particles to the hydrogen peroxide, the amount of the phosphorus oxoacid does not refer to the amount of the solution of the phosphorus oxoacid, but to the amount of the phosphorus oxoacid itself.

In the method (a), the total amount of the solution containing hydrogen peroxide and the solution containing phosphorus oxoacid is preferably 0.05 to 5.0 parts by weight with respect to 100.0 parts by weight of the base particles. Parts, particularly preferably 0.1 to 4.5 parts by mass, are mixed, so that the contact treatment can be performed efficiently with good workability. It is preferable in that it can be used as it is.

In the methods (a) and (b), the contact product of the substrate particles with hydrogen peroxide and phosphorus oxoacid may be powder, slurry or paste depending on the amount of solution added. , becomes solid. Therefore, the mixing treatment for contacting the base particles with the hydrogen peroxide and the phosphorus oxoacid may be carried out by appropriately selecting a conventional wet or dry mixing treatment depending on the properties of the resulting mixture. good.

The device used for wet mixing is not particularly limited as long as a uniform mixture (contact product) can be obtained. Equipment such as mills, sand grind mills, attritors and intensive agitators may be mentioned. The wet mixing process is not limited to the mixing process by mechanical means exemplified above.

As a method of dry mixing, mechanical means is preferable because a uniform mixture can be obtained. The device used for dry mixing is not particularly limited as long as a homogeneous mixture can be obtained. Blenders, V-type mixers, conical blenders, jet mills, cosmomizers, paint shakers, bead mills, ball mills and the like can be mentioned. At the laboratory level, a home-use mixer or manual work is sufficient.

In the methods (a) and (b), the temperature at which the substrate particles are brought into contact with hydrogen peroxide and phosphorus oxoacid is not particularly limited, but in many cases it is 10 to 50°C, preferably 20°C. ~40°C. In the case of method (a), the temperature at which the solution containing phosphorus oxoacid or the solution containing hydrogen peroxide is brought into contact with the substrate particles is shown.

In the methods (a) and (b), the time during which the substrate particles are brought into contact with hydrogen peroxide and the oxoacid of phosphorus is not critical in the present production method, and is often 10 minutes or longer, preferably is 15-60 minutes. In the case of the method (a), the time for contacting the substrate particles with the solution containing phosphorus oxoacid or the solution containing hydrogen peroxide is shown.

Thus, in the contacting step, the substrate particles are brought into contact with the hydrogen peroxide and the phosphorus oxoacid to modify the surface of the substrate particles and the contact product of the hydrogen peroxide and the phosphorus oxoacid. get the particles.

In the method for producing surface-modified particles of the present invention, a suitable range of the amount of the solution containing hydrogen peroxide and the oxoacid of phosphorus, or the amount of the solution containing the hydrogen peroxide and the solution containing the oxoacid of phosphorus In the preferred range of, the amount of the solution containing hydrogen peroxide and the oxoacid of phosphorus added to the substrate particles is small, or the amount of the solution containing the solution containing hydrogen peroxide and the solution containing the oxoacid of phosphorus is small. Therefore, the properties of the contact material obtained by contacting the substrate particles with the method (a) or (b) basically maintains the powder state without drying.

Therefore, in the method for producing surface-modified particles of the present invention, after the contacting step, a drying treatment may be performed as necessary. Further, in the method for producing surface-modified particles of the present invention, pulverization, pulverization, classification, etc. may be carried out as necessary. In the case where the drying treatment is performed, the entire contact product of the substrate particles and the hydrogen peroxide and the oxoacid of phosphorus may be dried as it is.

Then, in the method for producing surface-modified particles of the present invention, by performing the contacting step, or after performing the contacting step, drying treatment, pulverization, pulverization, classification, etc. are performed as necessary, A surface-modified particle is obtained.

When only hydrogen peroxide is brought into contact with the substrate particles, the hydrogen peroxide on the surface of the particles decomposes over time after the contact. can't keep

On the other hand, in the present invention, the hydrogen peroxide and the phosphorus oxoacid can be brought into contact with the substrate particles together with the phosphorus oxoacid on the particle surface. Then, hydrogen peroxide and phosphorus oxoacid present on the particle surface interact with each other, and the hydrogen peroxide is stabilized by the phosphorus oxoacid. can exist in a state of

EXAMPLES The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples.

(Preparation of substrate particles)
15 parts by mass of commercially available tungsten trioxide (WO ₃ ; average particle size: 1.2 μm) was placed in a beaker, and 84 parts by mass of pure water was further added.
A 15% by mass slurry containing tungsten trioxide was prepared by stirring at room temperature (25° C.) for 120 minutes. The average particle size of the solid content in the slurry was 1.2 µm.
Next, zirconium hydroxide, 85% by mass phosphoric acid aqueous solution and magnesium hydroxide were added to the slurry so that the molar ratio of Zr:W:P:Mg in the slurry was 2.00:1.00:2.00:0. After addition at room temperature (25° C.) so as to give 0.10, the temperature was raised to 80° C. and the reaction was carried out with stirring for 4 hours.
After completion of the reaction, 1 part by mass of polycarboxylic acid ammonium salt was charged as a dispersant, and while stirring the slurry, it was supplied to a media-stirring bead mill charged with zirconia beads with a diameter of 0.5 mm, mixed for 15 minutes, and wet pulverized. did The average particle size of the solid content in the slurry after wet pulverization was 0.3 μm.
Then, the slurry was supplied to a spray dryer set at 220° C. at a supply rate of 2.4 L/h to obtain a reaction precursor. As a result of X-ray diffraction of the obtained reaction precursor, only diffraction peaks of tungsten trioxide were observed. When analyzed by FT-IR, it had an infrared absorption peak at 950 to 1150 cm ^-1 and the maximum value of the infrared absorption peak during this period appeared at 1042 cm ^-1 .
Next, the obtained reaction precursor was subjected to a firing reaction in the atmosphere at 1050° C. for 2 hours to obtain a white fired product.
X-ray diffraction analysis of the fired product obtained revealed that the fired product was single-phase Zr ₂ (WO ₄ )(PO ₄ ) ₂ . This was used as base particles.

(Preparation of solution containing hydrogen peroxide and phosphoric acid)
A 30.0% by mass hydrogen peroxide aqueous solution and an 85.0% by mass phosphoric acid aqueous solution were mixed at a weight ratio of 10:2 to prepare a solution containing hydrogen peroxide and phosphoric acid.

(Example 1)
100.0 g of the substrate particles prepared above were placed in a zippered plastic bag. Then, 0.40 g of the solution containing hydrogen peroxide and phosphorus oxoacid prepared above was added thereto and mixed manually for 10 minutes at room temperature (25° C.) to obtain a contact product, 25° C.) and left in a closed container for 20 days to obtain a surface-modified particle sample.

(Example 2)
100.0 g of the substrate particles prepared above were placed in a zippered plastic bag. Then, 0.60 g of the solution containing hydrogen peroxide and phosphorus oxoacid prepared above was added thereto and mixed manually for 10 minutes at room temperature (25° C.) to obtain a contact product, 25° C.) and left in a closed container for 20 days to obtain a surface-modified particle sample.

(Example 3)
100.0 g of the substrate particles prepared above were placed in a zippered plastic bag. Then, 0.80 g of the solution containing hydrogen peroxide and phosphorus oxoacid prepared above was added thereto and mixed manually for 10 minutes at room temperature (25° C.) to obtain a contact product, 25° C.) and left in a closed container for 20 days to obtain a surface-modified particle sample.

(Comparative example 1)
The substrate particles prepared above were used as they were and were used as surface-modified particle samples.

(Comparative example 2)
100.0 g of the substrate particles prepared above were placed in a zippered plastic bag. Next, 0.33 g of ion-exchanged water was added to this, and mixed manually for 10 minutes at room temperature (25° C.) to obtain a mixture, which was used as a surface-modified particle sample.

(Comparative Example 3)
100.0 g of the substrate particles prepared above were placed in a zippered plastic bag. Next, 0.40 g of a 30.0% by mass aqueous hydrogen peroxide solution is added, mixed manually for 10 minutes at room temperature (25° C.) to obtain a mixture, and placed in a sealed container at room temperature (25° C.) for 20 days. This was used as a surface-modified particle sample.

(Water elution test)
4.0 g of the surface-modified particle sample was added to 10.0 mL of pure water, stirred and mixed at room temperature (25° C.) for 1 minute, and then allowed to stand at room temperature (25° C.). After 20 hours, the supernatant was filtered through a 0.5 μm membrane filter, and the obtained filtrate was analyzed with hydrogen peroxide test paper (manufactured by Merck Ltd., product name: Quantofix Peroxide 25) to determine the concentration of hydrogen peroxide in the filtrate. was analyzed. To determine the hydrogen peroxide concentration of the filtrate, the hydrogen peroxide concentration was changed at intervals of 0.5 mass ppm, 2 mass ppm, 5 mass ppm, 10 mass ppm and 25 mass ppm. It was done by

Claims (6)

A surface-modified particle comprising a substrate particle and hydrogen peroxide and phosphorus oxoacid present on the surface of the substrate particle. 2. The surface-modified particles according to claim 1, wherein said surface-modified particles are contact products of base particles, hydrogen peroxide and phosphorus oxoacid. 2. The surface-modified particles according to claim 1, wherein the surface-modified particles are obtained by mixing zirconium tungstate phosphate particles with a solution of hydrogen peroxide and phosphorus oxoacid. . 4. The surface-modified particles according to any one of claims 1 to 3, wherein the phosphorus oxoacid is phosphoric acid. A method for producing surface-modified particles, comprising a contacting step of contacting substrate particles with hydrogen peroxide and phosphorus oxoacid to obtain surface-modified particles. 6. The method for producing surface-modified particles according to claim 5, wherein the contacting step is performed by mixing the substrate particles and a solution containing hydrogen peroxide and phosphorus oxoacid.