Containerized titanium oxide particles and manufacturing method of the same, and titanium oxide storage container

Abstract

To provide a storage form and method for titanium oxide particles that can reduce changes in moisture content of titanium oxide particles during storage.SOLUTION: Containerized titanium oxide particles comprise a container and titanium oxide particles contained in the container, wherein the water vapor permeability of the container is 1.0 g / (m2 24h) or less at a temperature of 40°C and relative humidity of 90% RH, and the total pore volume of the titanium oxide particles is 0.80×10-3 m3 / kg or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to titanium oxide particles in a container, a method for producing the same, and a titanium oxide storage container.

Background Art

[0002] The industrial application fields of titanium oxide are extremely wide, and typical examples include cosmetics, ultraviolet ray shielding materials, and additives to silicone rubber. In recent years, titanium oxide has also been widely used as a raw material for barium titanate used as a material for electronic components. Although "titanium oxide" is described as titanium dioxide in Japanese Industrial Standards (JIS), since titanium oxide is widely used as a common name, titanium dioxide (TiO2) is abbreviated as titanium oxide in the present disclosure.

[0003] The surface of titanium oxide is basically covered with Ti atoms, O atoms, and OH groups chemically bonded to Ti atoms. Further, several layers of water molecules are physically adsorbed to these OH groups by hydrogen bonds to constitute moisture measured as loss on drying.

[0004] Since this moisture repeats adsorption and desorption on the surface of titanium oxide depending on the humidity of the environment, it is likely to vary under the influence of seasons or weather. For example, when synthesizing barium titanate by reacting BaO and TiO2, in order to strictly control the ratio of BaO and TiO2, it is necessary to completely dry and weigh titanium oxide immediately before synthesis, which significantly increases the equipment or economic burden. Further, since micronized titanium oxide has a large surface area per unit mass, that is, a large specific surface area, the amount of adsorbed moisture is large, and the variation in the amount at the time of raw material input is also large. Recently, there has been a strong demand for micronization of titanium oxide, and the variation in the input amount and the accompanying yield reduction have been more significant.

[0005] In Patent Document 1, when packing fine titanium dioxide particles in a resin bag, the BET specific surface area is 10 to 200 m 2Water droplets with a droplet diameter of 5 to 500 μm are sprayed onto particulate titanium dioxide having a BET specific surface area of 5 to 50 m² / g, and the particulate titanium dioxide carrying the water droplets is sealed in a resin bag, and the titanium dioxide is stored under conditions of a temperature of 5 to 50°C and a relative humidity of 60 to 95%, whereby fluctuations in the adsorbed water content of the particulate titanium dioxide are reduced.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] Since titanium dioxide used as a raw material for electronic materials such as barium titanate is becoming finer, it is difficult to control the water content. If the water content cannot be appropriately controlled, product quality fluctuations, performance degradation, or yield reduction will occur.

[0008] The present disclosure provides titanium dioxide particles in a container, a storage container therefor, and a manufacturing method capable of reducing fluctuations in the water content of the titanium dioxide particles during storage.

Means for Solving the Problems

[0009] The present disclosure includes the following aspects. [Aspect 1] A container containing titanium dioxide particles accommodated in the container, wherein the water vapor permeability of the container is 1.0 g / (m 2 ·24 h) or less at a temperature of 40°C and a relative humidity of 90% RH, and the total pore volume of the titanium dioxide particles is 0.80×10 -3 m 3 / kg or less, titanium dioxide particles in a container. [Aspect 2] The mesopore volume of the titanium dioxide particles is 0.75×10 -3 m 3The titanium oxide particles in a container according to aspect 1, which are / kg or less. [Aspect 3] Comprising a container and titanium oxide particles accommodated in the container, wherein the water vapor permeability of the container is 1.0 g / (m 2 ·24 h) or less at a temperature of 40 °C and a relative humidity of 90% RH, and the mesopore volume of the titanium oxide particles is 0.75×10 -3 m 3 / kg or less, the titanium oxide particles in a container. [Aspect 4] wherein the total pore volume of the titanium oxide particles is 0.80×10 -3 m 3 / kg or less, the titanium oxide particles in a container according to aspect 3. [Aspect 5] The container contains aluminum, the titanium oxide particles in a container according to any one of aspects 1 to 4. [Aspect 6] The container contains aluminum and a resin, the titanium oxide particles in a container according to any one of aspects 1 to 5. [Aspect 7] The container contains an aluminum laminate film, the titanium oxide particles in a container according to any one of aspects 1 to 6. [Aspect 8] wherein the anatase content of the titanium oxide particles is 70% or more and 100% or less, the titanium oxide particles in a container according to any one of aspects 1 to 7. [Aspect 9] wherein the BET specific surface area of the titanium oxide particles is 5 m 2 / g or more and 500 m 2 / g or less, the titanium oxide particles in a container according to any one of aspects 1 to 8. [Aspect 10] wherein the total pore volume of the titanium oxide particles is 0.01×10 -3 m 3 / kg or more, the titanium oxide particles in a container according to any one of aspects 1 to 9. [Aspect 11] The change rate of the water content when the titanium oxide particles in the container are stored in an environment of 50°C and 90% RH for 14 days is from -2.0 mass% to 2.0 mass%, and the titanium oxide particles in the container according to any one of Aspects 1 to 10. [Aspect 12] The total pore volume is 0.80×10 -3 m 3 / kg or less, and a storage container for titanium oxide particles, wherein the water vapor permeability of the titanium oxide particle container is 1.0 g / (m 2 ·24 h) or less at a temperature of 40°C and a relative humidity of 90% RH, a storage container for titanium oxide particles. [Aspect 13] The total pore volume is 0.80×10 -3 m 3 / kg or less, and the titanium oxide particles are stored in a container having a water vapor permeability of 1.0 g / (m 2 ·24 h) or less at a temperature of 40°C and a relative humidity of 90% RH, and the opening of the container is sealed, a method for producing titanium oxide particles in a container. [Advantages of the Invention]

[0010] According to the present disclosure, it is possible to provide titanium oxide particles in a container, a storage container therefor, and a production method thereof, which can reduce the variation in the water content of the titanium oxide particles during storage. [Modes for Carrying Out the Invention]

[0011] Hereinafter, embodiments for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In the following embodiments, the constituent elements (including element steps, etc.) are not essential unless otherwise specified. The same applies to numerical values and their ranges, which do not limit the present invention. Further, various changes and modifications can be made by those skilled in the art within the scope of the technical idea of the present invention.

[0012] In the present disclosure, in the numerical range indicated by using "~", the numerical values described before and after "~" are included as the minimum value and the maximum value, respectively.

[0013] In the numerical ranges described step by step in the present disclosure, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in other step-by-step descriptions. Further, in the numerical ranges described in the present disclosure, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.

[0014] In the present disclosure, the content ratio and proportion of each component mean the total content ratio and proportion of a plurality of substances corresponding to each component, unless otherwise specified when there are a plurality of substances corresponding to each component.

[0015] In the present disclosure, the particle diameter of each component means a value for a mixture of a plurality of types of particles corresponding to each component, unless otherwise specified when there are a plurality of types of particles corresponding to each component.

[0016] In the present disclosure, the term "layer" includes not only the case where it is formed over the entire region when observing the region where the layer exists, but also the case where it is formed only in a part of the region.

[0017] In the present disclosure, the average thickness of a layer is the average value of the thicknesses of the layer at any 10 locations.

[0018] In the present disclosure, "D50" is the particle diameter at which 50% is reached in the volume-based cumulative particle size distribution determined from the particle size distribution measured by the laser diffraction / scattering method.

[0019] [Titanium Oxide Particles in a Container] The titanium oxide particles in a container according to one embodiment include a container and titanium oxide particles accommodated in the container, wherein the water vapor permeability of the container is 1.0 g / (m 2 ·24 h) or less at a temperature of 40 °C and a relative humidity of 90% RH, and the total pore volume of the titanium oxide particles is 0.80×10 -3 m 3 / kg or less.

[0020] The titanium oxide particles in a container according to another embodiment include a container and the titanium oxide particles accommodated in the container, wherein the water vapor permeability of the container is 1.0 g / (m 2 ·24 h) or less at a temperature of 40°C and a relative humidity of 90%RH, and the mesopore volume of the titanium oxide particles is 0.75×10 -3 m 3 / kg or less.

[0021] As a result of the study by the present inventors, titanium oxide particles having a total pore volume of 0.80×10 -3 m 3 / kg or less, or a mesopore volume of 0.75×10 -3 m 3 / kg or less, when stored in a container having a water vapor permeability of 1.0 g / (m 2 ·24 h) or less at a temperature of 40°C and a relative humidity of 90%RH, the water content of the titanium oxide particles is stabilized, that is, it has been found that the change rate of the water content can be reduced.

[0022] In one embodiment, the change rate of the water content when the titanium oxide particles in the container are stored in an environment of a temperature of 50°C and a relative humidity of 90%RH for 14 days is -2.0 mass% or more and 2.0 mass% or less. According to this embodiment, the water content of the titanium oxide particles can be kept stable for a long period of time. The change rate of the water content is preferably -1.5 mass% or more and 1.5 mass% or less, and more preferably -1.0 mass% or more and 1.0 mass% or less. In the present disclosure, the water content is measured by the method described in the examples.

[0023] <Container> A. Water vapor permeability Since the water vapor permeability of the container is 1.0 g / (m 2 ·24 h) or less at a temperature of 40°C and a relative humidity of 90%RH, the permeation of moisture in the atmosphere into the container and the permeation of moisture in the container to the outside of the container are suppressed, and as a result, it is considered that the fluctuation of the water content of titanium oxide can be suppressed. From the same viewpoint, the water vapor permeability of the container is preferably 0.5 g / (m 2 ·24 h) or less at a temperature of 40°C and a relative humidity of 90%RH, and 0.3 g / (m 2· It is more preferable that it is below 24 h).

[0024] The water vapor permeability of the container is preferably 0.001 g / (m 2 · It is preferably 24 h) or more. Thereby, the manufacturing cost of the container can be suppressed, or an excessive increase in mass can be avoided to enhance the efficiency in transportation or storage. From the same viewpoint, the water vapor permeability of the container is preferably 0.01 g / (m 2 · It is more preferably 24 h) or more, and even more preferably 0.05 g / (m 2 · It is more preferably 24 h) or more.

[0025] B. Material The material of the container is not particularly limited, and examples thereof include resin, rubber, metal, and carbon. The material of the container may be only one kind or a combination of two or more kinds. Since the water vapor permeability is low, the container is preferably a container having a metal layer. The metal layer is preferably an aluminum layer. The container is more preferably a container having an aluminum layer and a resin layer. It is preferable that the entire region of the titanium oxide particle accommodating portion is covered with a metal layer such as an aluminum layer or an aluminum layer and a resin layer.

[0026] The aluminum layer functions as a barrier layer for protecting the content from gas, water vapor, light, etc. Examples of the aluminum layer include aluminum foil (AL foil) and aluminum vapor deposition film (AL film). Aluminum foil is preferable because the water vapor permeability of the container can be lowered and it is inexpensive in terms of cost.

[0027] The thickness of the aluminum layer is preferably 1 to 25 μm, more preferably 4 to 15 μm, and even more preferably 6 to 10 μm. When the thickness of the aluminum layer is 1 μm or more, the above water vapor permeability can be easily ensured and the impact durability can also be enhanced. When the thickness of the aluminum layer is 25 μm or less, the durability against bending can be enhanced.

[0028] The resin layer is not particularly limited as long as it has the effect of suppressing the oxidation of the aluminum layer. For example, polyolefin resins such as polyethylene resin (PE), high-density polyethylene resin (HDPE), low-density polyethylene resin (LDPE), linear low-density polyethylene resin (abbreviated as LLDPE or LLD), polypropylene resin (PP, OPP), etc.; polyester resins such as polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), polyethylene naphthalate resin (PEN), etc.; polyamide resins; and stretched films thereof. From the viewpoint of strength or dead hold property, polyester resins, particularly polyethylene terephthalate resin (PET), are preferred. From the viewpoint of flexibility, polyethylene resin is preferred. A resin layer formed by laminating two or more polyethylene resin layers, and a resin layer formed by laminating a polyethylene resin layer and a polyethylene terephthalate resin layer are more preferred because they have both strength and flexibility.

[0029] The thickness of the resin layer is preferably 6 to 70 μm, more preferably 9 to 50 μm, and still more preferably 10 to 40 μm.

[0030] The container preferably has a structure in which both sides of the aluminum layer are sandwiched by resin layers, such as resin layer 1 / aluminum layer / resin layer 2. Thereby, the oxidation of the aluminum layer can be suppressed.

[0031] Resin layer 1 and resin layer 2 may each be a single layer or a laminate of two or more layers. The resin layer preferably functions as a heat-sealing layer for sealing the edge of the aluminum layer.

[0032] C. Shape The shape of the container is not particularly limited, and examples thereof include a columnar shape, a rectangular parallelepiped shape, and a bag shape. The container may be deformable or non-deformable. When transporting or storing titanium oxide particles, it is preferably deformable, and a bag shape is preferred because it is lightweight and excellent in transportability or storability, and a stand bag or a three-way bag is more preferred. The container preferably has an aluminum laminate film in which a resin layer and an aluminum layer are laminated by lamination processing, and an aluminum laminate bag formed by forming the aluminum laminate film into a bag shape is more preferred.

[0033] <Titanium oxide particles> A. Total pore volume In one embodiment, the total pore volume of the titanium oxide particles is 0.80×10 -3 m 3 / kg or less. In this embodiment, it is easy to suppress the moisture content of the titanium oxide particles. From the same viewpoint, the total pore volume of the titanium oxide particles is preferably 0.70×10 -3 m 3 / kg or less, and more preferably 0.50×10 -3 m 3 / kg or less. In the present disclosure, the total pore volume is measured by the method described in the examples.

[0034] The total pore volume of the titanium oxide particles is preferably 0.01×10 -3 m 3 / kg or more. The titanium oxide particles of this embodiment show high reactivity because other components easily penetrate into the pores of the titanium oxide particles when used as a synthetic raw material. From the same viewpoint, the total pore volume of the titanium oxide particles is preferably 0.10×10 -3 m 3 / kg or more, and more preferably 0.15×10 -3 m 3 / kg or more.

[0035] B. Mesopore volume In one embodiment, the mesopore volume of the titanium oxide particles is 0.75×10 -3 m 3It is below / kg. In this embodiment, it is easy to suppress the water content of the titanium oxide particles. From the same perspective, the mesopore volume of the titanium oxide particles is 0.70×10 -3 m 3 / kg or less is preferable, and 0.30×10 -3 m 3 / kg or less is more preferable. In the present disclosure, the mesopore volume is measured by the method described in the examples.

[0036] The mesopore volume of the titanium oxide particles is preferably 0.01×10 -3 m 3 / kg or more. When used as a synthetic raw material, the titanium oxide particles of this embodiment show high reactivity because other components easily penetrate into the pores of the titanium oxide particles. From the same perspective, the mesopore volume of the titanium oxide particles is preferably 0.03×10 -3 m 3 / kg or more, and more preferably 0.05×10 -3 m 3 / kg or more.

[0037] C. Anatase content The anatase content of the titanium oxide particles is preferably 70% or more. Since anatase-type titanium oxide particles are superior in photoelectrochemical activity compared to other crystal systems such as rutile type, titanium oxide particles having an anatase content of 70% or more are suitable as raw materials for electronic materials and the like. From the same perspective, the anatase content of the titanium oxide particles is more preferably 75% or more, and even more preferably 78% or more. In the present disclosure, the anatase content is defined as the content of anatase-type crystals in the titanium oxide particles and is measured by the method described in the examples.

[0038] D. BET specific surface area The BET specific surface area of the titanium oxide particles is preferably 5 m 2 / g or more and 500 m 2 / g or less, more preferably 10 m 2 / g or more and 480 m 2 / g or less, and even more preferably 20 m 2 / g or more and 460 m 2 / g or less. When the BET specific surface area is 5 m 2If it is 500 m or more, titanium oxide particles excellent in reactivity can be obtained. If the BET specific surface area is 500 m 2 / g or less, the agglomeration of titanium oxide particles can be moderately suppressed and the dispersibility can be enhanced. In the present disclosure, the BET specific surface area is measured by the method described in the examples.

[0039] E.D50 Titanium oxide particles generally often form secondary particles in which their primary particles are aggregated. In the present disclosure, the particle size D50 in the aggregated state (aggregate of primary particles and secondary particles) of titanium oxide particles is measured by a laser diffraction particle size distribution apparatus, specifically by the method described in the examples.

[0040] The D50 of the titanium oxide particles is preferably 10 μm or less. D50 corresponds to the effective diameter (aggregation diameter) when the titanium oxide particles are put into the solvent, and the smaller D50 is, the better the dispersibility is. From the same viewpoint, the D50 of the titanium oxide particles is more preferably 5 μm or less, and still more preferably 3 μm or less. The D50 of the titanium oxide particles may be 1 nm or more. The D50 at this time corresponds to the primary particle diameter. The D50 of the titanium oxide particles may be 3 nm or more, and may be 10 nm or more.

[0041] F. Primary particle diameter The primary particle diameter of the titanium oxide particles is preferably 1 nm or more, more preferably 3 nm or more, and still more preferably 5 nm or more. When the primary particle diameter of the titanium oxide particles is 1 nm or more, it is easy to suppress excessive aggregation of the titanium oxide particles. The primary particle diameter of the titanium oxide particles is preferably 100 nm or less, more preferably 60 nm or less, and still more preferably 20 nm or less. When the primary particle diameter of the titanium oxide particles is 100 nm or less, it can be advantageously used as a synthetic raw material for electronic components that require fineness. In the present disclosure, the primary particle diameter is measured by the method described in the examples.

[0042] G. Tap density The tap density of the titanium oxide particles is 0.01 g / cm 3 or more and 0.80 g / cm 3The following is preferable. When the tap density of the titanium oxide particles is 0.01 g / cm 3 or more, it has a high density and is advantageous from the viewpoint of transportation cost and the like. From the same viewpoint, the tap density of the titanium oxide particles is preferably 0.05 g / cm 3 or more, more preferably 0.08 g / cm 3 or more. When the tap density of the titanium oxide particles is 0.80 g / cm 3 or less, the dispersibility of the titanium oxide particles in water is excellent. From the same viewpoint, the tap density of the titanium oxide particles is preferably 0.70 g / cm 3 or less, more preferably 0.60 g / cm 3 or less. In the present disclosure, the tap density is measured by the method described in the examples.

[0043] H. Chlorine (Cl) content The Cl (chlorine atom) content of the titanium oxide particles is preferably 0.20 mass% or less. When such titanium oxide particles are used as a raw material, the generation of by-products or the aggregation of particles can be suppressed in the subsequent process. For example, when titanium oxide particles having a Cl content of 0.20 mass% or less are used as a raw material for BaTiO3 or the like, the generation of flux during firing can be suppressed. The molten flux tends to localize, and a large amount of particle aggregation occurs in the localized part, which may cause quality variations between other parts. In addition, when the particles aggregate, the crystals of the BaTiO3 particles may grow into abnormal particles, which may reduce the dielectric properties of BaTiO3. From the viewpoint of more effectively suppressing the generation of flux, the Cl content in the titanium oxide particles is more preferably 0.15 mass% or less, and even more preferably 0.10 mass% or less.

[0044] I. Content of other impurities The Al content, S content, and Fe content of the titanium oxide particles are each preferably 0.05% by mass or less, and more preferably 0.01% by mass or less. The Si content and C content in the titanium oxide particles are each preferably 0.5% by mass or less, and more preferably 0.1% by mass or less. When titanium oxide particles with few impurities are used as a raw material, the generation of by-products or the aggregation of particles in the subsequent process can be suppressed. For example, when a dielectric is obtained using such titanium oxide particles as a raw material, it is possible to suppress the deterioration of dielectric properties due to the presence of impurities. When such titanium oxide particles are used for photocatalyst or solar cell applications, it is possible to prevent or suppress the decrease in transparency due to coloring by Fe, and also to prevent or suppress the decrease in the function as a photocatalyst or solar cell due to lattice defects caused by Al, S, etc.

[0045] <Method for producing titanium oxide particles> The method for producing titanium oxide particles will be described. The methods for producing titanium oxide are roughly classified into a vapor phase method and a liquid phase method. These methods will be described in order, but are not limited to this description.

[0046] A. Vapor phase method The method for producing titanium oxide particles by the vapor phase method includes a reaction step of supplying a gas containing titanium tetrachloride heated preferably to 600°C or higher and less than 1100°C and an oxidizing gas heated to 600°C or higher and less than 1100°C as raw material gases to a reaction tube to obtain a reaction gas, and a cooling step of introducing a cooling gas to cool the reaction gas to obtain titanium oxide particles, and preferably further includes a dechlorination step.

[0047] (Reaction tube) The reaction tube may be a horizontal reaction tube, but a vertical reaction tube is preferred because it is easier to make the flow of various gases uniform, and a reaction tube with a circular cross-section is preferred. In the case of a circular vertical reaction tube, a preheated raw material gas and an oxidizing gas are introduced downward into the reaction tube from the upper end of the heated reaction tube through their respective supply pipes to generate a reaction gas. This step is called the reaction step. A cooling gas outlet is provided on the inner wall of the reaction tube, and the cooling gas is blown out from there and mixed with the reaction gas to cool the reaction gas. This step is called the cooling step.

[0048] The section from the raw material gas inlet to the cooling gas outlet in the reaction tube is called the reaction region, and the section from the cooling gas outlet to the discharge port side is called the cooling region. When there are multiple cooling gas outlets, the section from the raw material gas inlet to the first cooling gas outlet in the reaction tube is called the reaction region, and the section from the first cooling gas outlet to the discharge port side is called the cooling region.

[0049] The cooled titanium oxide particles and the remaining gas are discharged to the outside at the lower part of the reaction tube. Note that the reaction gas may contain titanium oxide as a reaction product.

[0050] A-1. Reaction Step The temperature of the reaction region where the titanium tetrachloride-containing gas and the oxidizing gas are introduced is preferably 800 °C or higher and less than 1100 °C, and more preferably 850 °C or higher and less than 1050 °C. By increasing the temperature of the reaction region, the reaction is completed simultaneously with the mixing of these gases, so that homogeneous nucleation can be promoted and the reaction zone can be reduced. When the temperature of the reaction region is 800 °C or higher, the reaction proceeds sufficiently and chlorine hardly remains inside the titanium oxide particles. When the temperature of the reaction region is less than 1100 °C, the formation of rutile-type titanium oxide particles is suppressed, and the anatase content tends to be increased.

[0051] The oxidizing gas contains at least one of oxygen gas and water vapor, and can further contain other gases such as nitrogen. Since it is inexpensive, the oxidizing gas preferably contains water vapor.

[0052] A-2. Cooling Step The cooling gas is not particularly limited, and for example, air, nitrogen gas, or carbon monoxide can be used. From the viewpoint of enhancing the cooling effect, the temperature of the cooling gas is preferably from 0°C to 100°C, more preferably from 10°C to 90°C. Sprayed water can also be used in combination with the cooling gas.

[0053] A-3. Dechlorination step The produced titanium oxide particles are preferably subjected to dechlorination treatment in the dechlorination step. Dechlorination of the titanium oxide particles by heating is preferably carried out by contacting the titanium oxide particles with water vapor while the mass ratio of water to the titanium oxide particles (mass of water vapor / mass of titanium oxide particles) is 0.01 or more, preferably 0.04 or more, and heating at a temperature of 200°C or higher and 550°C or lower, preferably 250°C or higher and 450°C or lower. By setting the temperature to 550°C or lower, sintering of the titanium oxide particles can be suppressed and the primary particle diameter can be made uniform. By setting the temperature to 200°C or higher, the efficiency of dechlorination can be increased. If the mass ratio of water to the titanium oxide particles is 0.01 or more, particle growth can be effectively suppressed. The mass ratio of water to the titanium oxide particles is preferably from 0.01 to 3, more preferably from 0.04 to 2, and still more preferably from 0.2 to 1.8.

[0054] In the titanium oxide particles of the present disclosure, almost no chlorine exists inside the particles and most of the chlorine exists on the particle surface. Therefore, it is also possible to perform low-chlorination wetly, for example, to remove it by washing with water. Examples of the wet method include a method in which titanium oxide particles are suspended in pure water and chlorine transferred to the liquid phase is separated outside the system by an ultrafiltration membrane, a reverse osmosis membrane, a filter press, or the like.

[0055] B. Liquid phase method The method for producing titanium oxide particles by the liquid phase method includes a reaction step of hydrolyzing an aqueous solution of titanium tetrachloride, and a cooling step of cooling the reaction solution thereafter, and preferably further includes a dechlorination step.

[0056] B-1. Reaction step When a titanium tetrachloride aqueous solution, preferably at room temperature (about 20°C), is mixed with water preheated to 80°C or higher, and the mixture is heated and maintained at 80°C or higher, turbidity can be observed simultaneously with the mixing, and titanium oxide particles can be obtained immediately after mixing. The preheating temperature of the water is preferably 80°C or higher and below the boiling point, more preferably 90°C or higher and below the boiling point. By setting the preheating temperature of the water to 80°C or higher, the hydrolysis of titanium tetrachloride can be promoted.

[0057] Mixing can be carried out using a stirring device. As the stirring device, a generally widely used rotary blade stirrer can be used. The shape of the rotary blade can be a common one such as a propeller shape, a turbine shape, or a comb shape. In order to enhance the stirring efficiency, two or more stirrers can be installed in the reaction tank, or baffles can be installed. Not limited to a batch reactor, a continuous tank reactor or a tubular reactor having a structure in which titanium tetrachloride and water are continuously introduced while the reaction tank is a continuous tank and the reaction solution is taken out on the opposite side of the inlet can also be used.

[0058] B-2. Cooling step The time for cooling from the completion of the mixing of the titanium tetrachloride aqueous solution and water to below 60°C is preferably within 15 minutes, more preferably within 10 minutes, and even more preferably within 5 minutes. If the mixture is maintained at 60°C or higher for a long time, the formed primary particles may join together, and the secondary particles may grow, resulting in a decrease in dispersibility. By cooling the mixture to below 60°C immediately after the formation of the primary particles, the growth of the secondary particles can be suppressed, and particles with high dispersibility can be obtained.

[0059] B-3. Dechlorination step In the dechlorination step, the same method as in the dechlorination step in the gas phase method can be used.

[0060] <Method for producing titanium oxide particles in a container> The method for producing titanium oxide in a container includes a step of accommodating the titanium oxide particles in the container and sealing the opening of the container. The opening of the container can be sealed by thermocompression bonding using a sealer as the sealing means.

Example

[0061] Hereinafter, examples and comparative examples will be specifically described, but the present invention is not limited thereto.

[0062] <Container> The container is a bag-shaped container made from a sheet having the following structure. In the description of the sheet structure, the first-described layer is the outermost layer, the last-described layer is the innermost layer, and the order of description represents the lamination order. Container 1, Container 2, and Container 3 are bags made of aluminum laminated film. Container 1: PET film (thickness 12 μm) / PE film (thickness 15 μm) / AL foil (thickness 9 μm) / PE film (thickness 15 μm) / LLDPE film (thickness 30 μm), water vapor permeability 0.06 g / (m 2 ·24 h) Container 2: PET film (thickness 12 μm) / PE film (thickness 15 μm) / AL foil (thickness 7 μm) / SPE film (thickness 15 μm) / PE film (thickness 40 μm), water vapor permeability 0.1 g / (m 2 ·24 h) Container 3: PET film (thickness 12 μm) / AL film (thickness 0.02 μm) / LDPE film (thickness 65 μm), water vapor permeability 5.9 g / (m 2 ·24 h) Container 4: LDPE film (thickness 70 μm), water vapor permeability 15 g / (m 2 ·24 h)

[0063] The water vapor permeability of the container was determined in accordance with JIS K 7129-2:2019 "Plastics - Films and Sheets - Method for Determining Water Vapor Permeability - Part 2: Infrared Sensor Method".

[0064] <Measurement Method> A. Total pore volume As a pretreatment, 0.1 g of titanium oxide particles heated to 180 °C and with nitrogen gas flowing for 20 minutes were used to measure the total pore volume using NOVA4200e manufactured by Quantachrome Corporation and nitrogen gas in accordance with JIS Z 8831-3:2010 "Method for Measuring Micropores by Gas Adsorption". The lower measurement limit was 1.1 nm, and the upper limit was where the relative pressure P / P0 between the measurement pressure P and the saturated vapor pressure P0 was 0.99.

[0065] B. Mesopore volume As a pretreatment, 0.1 g of titanium oxide particles heated to 180 °C and with nitrogen gas flowing for 20 minutes were used to measure the mesopore volume using NOVA4200e manufactured by Quantachrome Corporation and nitrogen gas in accordance with JIS Z 8831-3:2010 "Method for Measuring Micropores by Gas Adsorption". The lower measurement limit was 2 nm, and the upper limit was 50 nm.

[0066] C. Anatase content The content of anatase-type crystals (anatase content) in the titanium oxide particles was measured by the powder X-ray diffraction method. Specifically, for the dried titanium oxide particles, using PANalytical's "X'pertPRO" as the measurement device, a copper target, and Cu-Kα1 radiation, X-ray diffraction measurements were performed under the conditions of a tube voltage of 45 kV, a tube current of 40 mA, a measurement range of 2θ = 10 to 80 deg, a sampling width of 0.0167 deg, and a scanning speed of 0.0192 deg / s. The peak height (Ha) of the maximum peak corresponding to the anatase-type crystal, the peak height (Hb) of the maximum peak corresponding to the brookite-type crystal, and the peak height (Hr) of the maximum peak corresponding to the rutile-type crystal were determined, and the content of anatase-type crystals (anatase content) in the titanium oxide particles was determined by the following calculation formula. Anatase content (%) = {Ha / (Ha + Hb + Hr)} × 100

[0067] D. BET specific surface area In accordance with JIS R 1626:1996 "Method for Measuring Specific Surface Area of Fine Ceramic Powders by Gas Adsorption BET Method", a fully automatic BET specific surface area measuring device ("Macsorb HM model-1208", manufactured by Mountech Co., Ltd.) was used. For 0.1 g of titanium oxide particles heated to 180°C and with nitrogen gas flowing for 20 minutes as a pretreatment, the BET specific surface area was measured using nitrogen gas as the adsorbate by the BET three-point method. The applicable range of the BET method was set such that the range of the relative pressure P / P0 between the measurement pressure P and the saturated vapor pressure P0 was 0.00 to 0.95.

[0068] E.D50 In a 100 mL tall beaker, 0.05 g of titanium oxide particles, 50 mL of pure water, and 100 μL of a 10 mass% sodium hexametaphosphate aqueous solution were added to form a slurry. While stirring the slurry in the tall beaker using a rod made of polytetrafluoroethylene with a diameter of φ8 mm, ultrasonic waves were irradiated for 3 minutes (50 KHz, 100 W). Stirring was performed only for 1 minute from the start of ultrasonic irradiation. The ultrasonic bath was box-shaped with an internal size of 230 mm × 200 mm × 152 mm, and the water volume was 450 mL. The position of the tall beaker during ultrasonic irradiation was near the center of the ultrasonic bath. Using this slurry as a sample, the particle size D50, which is 50% in the volume-based cumulative particle size distribution, was measured using a laser diffraction particle size distribution measuring device (Microtrac MT3300EXII, manufactured by Microtrac).

[0069] F. Primary particle size 1 g of titanium oxide particles was put into 100 mL of ethanol. After ultrasonic irradiation (30 W, 5 min), the dispersion was collected with a Pasteur pipette, and about 0.05 g was dropped onto an aluminum foil. It was naturally dried in a laboratory atmosphere, the aluminum foil was fixed to an SEM sample stage, and measurement was carried out using a field emission scanning electron microscope (S-5500, Hitachi High-Technologies Fielding Corporation). As the measurement conditions for SEM, the acceleration voltage was set to 2.0 kV. An image was taken such that the number of primary particles per field of view was 200 to 300, and the primary particle diameter (equivalent circle diameter, specifically the Heywood diameter) of each of about 200 to 300 particles on the image was determined using image analysis software. As the image analysis software, Particle Analysis Ver3 of Sumitomo Metal Technology Corporation or Mac-View Ver3 of Mount Tech Co., Ltd. was used. The same operation was performed for another field of view of the same sample, and the same operation was repeated until the total number of particles used for the calculation of primary particles exceeded at least 1000. The particle size at which the cumulative total value of the reference amount from the smaller particle size in the cumulative particle size distribution based on the obtained number was 50% of the total cumulative value was calculated as the primary particle diameter.

[0070] G. Tap density Using a Powder Tester PT-X (Hosokawa Micron Corporation) as a tap density measuring device, titanium oxide particles were filled up to the upper end of a 100 mL fixed-volume cup and capped, and the bulk density was determined by measuring the powder mass after tapping the container for 3 minutes under the conditions of a tap stroke of 70 mm and 180 times.

[0071] H. Chlorine (Cl) content The Cl content in the titanium oxide particles was measured by the silver nitrate potentiometric titration method. Specifically, 0.5 g of titanium oxide particles was weighed. Next, a silver nitrate solution (concentration 0.02 mol) was dropped into the solution of this titanium oxide particle, and the mass of chlorine atoms in the solution was determined by measuring the potential difference, and the chlorine content (mass%) was calculated.

[0072] I. Content of other impurities The measurement methods for each impurity are as shown below. Fe: Atomic absorption spectrometry (Z-2300 atomic absorption photometer, Hitachi High-Tech Corporation) Al, Si: X-ray fluorescence analysis (XRF) (Simaltrex 10, Rigaku Corporation) C, S: Combustion-infrared absorption method using a high-frequency induction heating furnace

[0073] J. Moisture content Using a heating and drying moisture meter MX-50 (A&D Company, Limited), 2 g of titanium oxide powder was heated in an air atmosphere to 200 °C and then infrared heating was performed at 120 °C until the mass change became 0.01 mass% or less. The mass of the titanium oxide powder was measured, and the mass reduction was calculated as all moisture.

[0074] Synthesis Example 1 Using a vertical reaction tube with a circular cross-section, a mixed raw material gas (G1) with a titanium tetrachloride flow rate of 16.9 Nm 3 / hr and a nitrogen gas flow rate of 18.0 Nm 3 / hr was heated to 1030 °C, and at a total flow rate of 34.9 Nm 3 / hr, an oxygen gas flow rate of 7.8 Nm 3 / hr, a water vapor flow rate of 26.2 Nm 3 / hr and a nitrogen gas flow rate of 0.1 Nm 3 / hr of a mixed oxidizing gas (G2) was heated to 820 °C, and at a total flow rate of 34.1 Nm 3 / hr, they were introduced from the top of the reaction tube respectively to generate a reaction gas. Nitrogen gas was introduced as a purge medium from the inner wall of the reaction tube in the reaction region (1050 °C). In the cooling region, air at 25 °C was introduced as a cooling gas to obtain titanium oxide particle raw materials. Then, the titanium oxide particle raw materials were collected at the lower part of the reaction tube using a polytetrafluoroethylene bag filter.

[0075] The obtained titanium oxide particle raw materials were passed through a cylindrical rotary heating furnace and dechlorinated under the conditions where the mass ratio of steam mixed with air to the titanium oxide particle raw materials (mass of steam / mass of titanium oxide particle raw materials) was 0.06 and the temperature was 450 °C to obtain titanium oxide particles 1.

[0076] Synthesis Example 2 Using a vertical reaction tube with a circular cross-section, the flow rate of titanium tetrachloride was 3.7 Nm 3 / hr and the flow rate of nitrogen gas was 25.3 Nm 3 / hr of the mixed raw material gas (G1) was heated to 1030 °C, and the total flow rate was 29.0 Nm 3 / hr. At a total flow rate of 35.4 Nm 3 / hr, the flow rate of oxygen gas was 3.2 Nm 3 / hr, the flow rate of steam was 31.9 Nm 3 / hr and the flow rate of nitrogen gas was 0.3 Nm 3 / hr of the mixed oxidizing gas (G2) was heated to 910 °C and introduced from the top of the reaction tube at a total flow rate of 35.4 Nm

[0077] / hr to generate a reaction gas. Nitrogen gas was introduced as a purge medium from the inner wall of the reaction tube in the reaction region (850 °C). In the cooling region, air at 25 °C was introduced as a cooling gas to obtain titanium oxide particle raw materials. Thereafter, the titanium oxide particle raw materials were collected at the lower part of the reaction tube using a polytetrafluoroethylene bag filter.

[0078] Synthesis Example 3 690 mL of ion-exchanged water was placed in a reaction tank equipped with a comb-shaped stirrer and preheated to 95 °C. While maintaining the stirring speed at about 300 rpm and heating to keep the temperature at 95 °C, 50 g of an aqueous solution of titanium tetrachloride at room temperature (20 °C) (Ti concentration: 18% by mass) was dropped into the reaction tank over 30 seconds and stirred and mixed in the reaction tank. Since it is uniformly mixed immediately after dropping titanium tetrachloride into water, the dropping time can be approximated as the mixing time. After all the titanium tetrachloride was dropped, the mixed solution was maintained at 95 °C for 4 minutes. Thereafter, the reaction tank was cooled to 50 °C in an ice bath in less than 1 minute. At this time, it took 40 seconds until the temperature in the reaction tank reached 60 °C. Hydrochloric acid generated by the reaction was removed using an electrodialysis device to obtain a titanium oxide sol. After drying the titanium oxide sol in a dryer at 100 °C, it was crushed in a mortar to obtain titanium oxide particles 3.

[0079] Examples 1 to 4, Comparative Examples 1 to 3 Any 100 g of one of titanium oxide particles 1 to 3 was filled into one of containers 1 to 4 in the combinations of the examples and comparative examples described in Table 2, and sealed by thermocompression bonding with a sealer. Next, the container filled with titanium oxide particles was left standing in an environment of a temperature of 50°C and a relative humidity of 90% RH for a predetermined time, and then the moisture content of the titanium oxide particles was measured. If the moisture content change rate after storage for 14 days is -2.0 mass% or more and 2.0 mass% or less, it indicates that the moisture content is stable. For the measurements on the 5th, 7th, 10th, 14th, and 15th days, titanium oxide in separate containers was prepared respectively, and the titanium oxide in a separate container was measured for each measurement. The measured samples and results are shown in Table 2. In Table 2, "-" indicates that the measurement was not performed.

[0080]

Table 1

[0081]

Table 2

[0082] For Examples 1 to 4 in which any one of titanium oxide particles 1 to 3 was housed in Container 1 or 2 having a water vapor transmission rate of 1.0 g / (m 2 ·24 h) or less at a temperature of 40°C and a relative humidity of 90% RH, the change rate of the moisture content was ±1.2% or less in all cases, and the moisture content could be stored in a stable state. Regarding Example 3 and Example 4, by linearly interpolating the moisture content after 10 days and 15 days, it is presumed that the moisture content after 14 days also showed the same moisture content as after 10 days and 15 days.

[0083] On the other hand, for Titanium Oxide Particles 1 or 2 with a water vapor transmission rate of 1.0 g / (m 2· Among Comparative Examples 1 to 3 contained in container 3 or container 4 with an RH exceeding 24 h), the change rate of the water content was all 43.8% or more, plus or minus, and the water content had increased significantly. Regarding Comparative Example 3, by linearly interpolating the water contents after 10 days and 15 days, it is estimated that the water content after 14 days was 9.89% by mass and the change rate was 190.8%.

Claims

1. comprising a container and titanium oxide particles contained in the container, The water vapor permeability of the container is 1.0 g / (m ２ ·24 h) or less at a temperature of 40°C and a relative humidity of 90% RH, and the total pore volume of the titanium oxide particles is 0.80 × 10 －３ m ３ / kg or less. Titanium oxide particles in a container.

2. The mesopore volume of the titanium oxide particles is 0.75×10 －３ m ３ / kg or less, and the titanium oxide particles in a container according to claim 1.

3. comprising a container and titanium oxide particles contained in the container, The water vapor permeability of the container is 1.0 g / (m ２ ·24 h) or less at a temperature of 40°C and a relative humidity of 90% RH, and the mesopore volume of the titanium oxide particles is 0.75×10 －３ m ３ / kg or less. Titanium oxide particles in a container.

4. The total pore volume of the titanium oxide particles is 0.80 × 10 －３ m ３ / kg or less, and the titanium oxide particles in a container according to claim 3.

5. The titanium oxide particles in a container according to any one of claims 1 to 4, wherein the container has an aluminum layer.

6. The titanium oxide particles in a container according to any one of claims 1 to 4, wherein the container has an aluminum layer and a resin layer.

7. The titanium oxide particles in a container according to any one of claims 1 to 4, wherein the container has an aluminum laminate film.

8. The titanium oxide particles in a container according to any one of claims 1 to 4, wherein the anatase content of the titanium oxide particles is 70% or more and 100% or less.

9. The BET specific surface area of the titanium oxide particles is 5 m ２ / g or more and 500 m ２ / g or less. The titanium oxide particles in a container according to any one of claims 1 to 4.

10. The total pore volume of the titanium oxide particles is 0.01×10 －３ m ３ / kg or more, and the titanium oxide particles in a container according to any one of claims 1 to 4.

11. The titanium oxide particles in a container according to any one of claims 1 to 4, wherein the change rate of the moisture content when the titanium oxide particles in the container are stored for 14 days in an environment of a temperature of 50°C and a relative humidity of 90% RH is -2.0 mass% or more and 2.0 mass% or less.

12. A titanium oxide particle storage container for storing titanium oxide particles with a total pore volume of 0.80 × 10 －３ m ３ / kg or less, wherein the water vapor permeability of the titanium oxide particle container is 1.0 g / (m ２ ·24 h) or less at a temperature of 40°C and a relative humidity of 90% RH. Titanium oxide particle storage container.

13. The total pore volume is 0.80×10 －３ m ３ / kg or less of titanium oxide particles are contained in a container having a water vapor permeability of 1.0 g / (m ２ ·24 h) or less at a temperature of 40°C and a relative humidity of 90% RH, and a step of sealing the opening of the container is included. A method for producing titanium oxide particles in a container.

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