Powder, composite material, and method for producing powder

Abstract

This powder contains a plurality of iron carbonate particles. The average particle diameter of the iron carbonate particles is 10 nm-1 μm inclusive, and the shape of the iron carbonate particles is spherical.

Description

Powders, composite materials, and methods for producing powders

[0001] The present disclosure relates to powders, composite materials, and methods for producing the powders. This application claims priority from Japanese Patent Application No. 2024-066906, filed on April 17, 2024. The entire contents of this Japanese patent application are incorporated herein by reference.

[0002] Patent Document 1 discloses a method for immobilizing atmospheric carbon dioxide using iron. Specifically, this method comprises steps 1 to 5. In step 1, iron is added to hydrochloric acid to obtain iron chloride. In step 2, an aqueous solution of iron chloride is electrolyzed to obtain hydrochloric acid and iron hydroxide. In step 3, brine is electrolyzed to obtain sodium hydroxide. In step 4, carbon dioxide is injected into an aqueous solution of sodium hydroxide to obtain sodium bicarbonate. In step 5, sodium bicarbonate and iron hydroxide are reacted to obtain iron carbonate. The iron carbonate is in particulate form.

[0003] Powders made of aggregates of iron carbonate particles can be used, for example, as one of the raw materials for composite materials. Composite materials are materials that contain resin and powders of iron carbonate particles dispersed in the resin. The iron carbonate particles impart properties such as flame retardancy to the composite material.

[0004] JP 2011-236059 A

[0005] The shape of iron carbonate particles in powders produced by conventional powder manufacturing methods is a rectangular column shape with corners. Composite materials made by mixing rectangular column-shaped iron carbonate particles with resin are prone to anisotropy. Anisotropy is the property in which physical properties change significantly depending on the direction. Anisotropic composite materials may have low strength against stress in a specific direction. Furthermore, anisotropic composite materials are prone to distortion when thermally expanded, which may cause damage to the composite material.

[0006] An object of the present disclosure is to provide a powder containing a plurality of iron carbonate particles that is less likely to cause anisotropy in a composite material containing this powder.

[0007] The powder of the present disclosure includes a plurality of iron carbonate particles, the iron carbonate particles having an average particle size of 10 nm or more and 1 μm or less, and the iron carbonate particles having a spherical shape.

[0008] The powders of the present disclosure are less likely to induce anisotropy in composite materials containing the powders.

[0009] Fig. 1 is a flowchart of a method for producing a powder described in an embodiment. Fig. 2 is an electron microscope photograph of a powder containing spherical iron carbonate particles. Fig. 3 is an electron microscope photograph further enlarging the powder shown in Fig. 2. Fig. 4 is an electron microscope photograph of a powder containing spherical iron carbonate particles and iron oxide hydroxide. Fig. 5 is an electron microscope photograph of a powder containing prismatic iron carbonate particles. Fig. 6 is a schematic diagram of a composite material described in an embodiment. Fig. 7 is a diagram showing the results of Test Example 1. Fig. 8 is a diagram showing the results of Test Example 2.

[0010] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described.

[0011] <1> A powder according to an embodiment of the present disclosure includes a plurality of iron carbonate particles, the iron carbonate particles having an average particle size of 10 nm (nanometers) or more and 1 μm (micrometers) or less, and the iron carbonate particles having a spherical shape.

[0012] The spherical shape of the iron carbonate particles can be easily confirmed by observing the iron carbonate particles under an electron microscope. Specifically, if the iron carbonate particles contained in the powder of the present disclosure are observed under an electron microscope and have no corners, the shape of the iron carbonate particles can be determined to be spherical.

[0013] In conventional methods for producing powders containing iron carbonate particles, iron carbonate particles are produced in accordance with the crystalline structure of iron carbonate. Therefore, the iron carbonate particles obtained by conventional powder production methods tend to have a prismatic shape. Furthermore, conventional iron carbonate particles can also be obtained from, for example, ores containing iron carbonate. The iron carbonate particles obtained by crushing the ores have a prismatic shape.

[0014] The iron carbonate particles in the powder of the present disclosure are fine. Therefore, in a composite material obtained by mixing the powder with a resin, the iron carbonate particles are easily dispersed uniformly in the resin. Furthermore, the iron carbonate particles in the powder are spherical. Therefore, anisotropy is unlikely to occur in the composite material obtained by mixing the powder with a resin.

[0015] <2> In the powder described in <1> above, the iron carbonate particles may have an average circularity of 0.80 or more.

[0016] The spherical shape of iron carbonate particles can also be quantitatively determined by their circularity. For example, circularity can be determined by analyzing a photograph of iron carbonate particles taken with an electron microscope and identifying the outline of the iron carbonate particles. The formula for calculating circularity is 4π×S / L. ２ where S is the area surrounded by the contour line, and L is the length of the contour line. The average circularity is the average value of the circularities of multiple iron carbonate particles. The parameter for calculating the average circularity is 10 or more.

[0017] <3> In the powder described in <1> or <2> above, when the total mass is taken as 100 mass%, the content of the plurality of iron carbonate particles may be 50 mass% or more.

[0018] The powder is produced by a powder production method according to an embodiment described below. In the powder production method according to the embodiment, iron carbonate particles are primarily produced, but FeO(OH) may also be produced as a by-product. FeO(OH) is also known as iron(III) oxide hydroxide. When the content of iron carbonate particles in the powder is 50% by mass or more, it is easy to impart the effects achieved by including iron carbonate particles to a composite material containing the powder.

[0019] <4> A composite material according to an embodiment of the present disclosure includes a resin and the powder according to any one of <1> to <3> above dispersed in the resin.

[0020] The composite material of the present disclosure, which contains spherical iron carbonate particles, is unlikely to have anisotropy. Rather, it can be said that the composite material of the present disclosure has isotropy.

[0021] <5> In the composite material described in <4> above, when the total mass is taken as 100 mass%, the content of the powder may be 20 mass% or more and 80 mass% or less.

[0022] When the powder content in the composite material is 20% by mass or more, the strength of the composite material is likely to be improved.When the powder content in the composite material is 80% by mass or less, the iron carbonate particles are less likely to fall off from the composite material, and the composite material is less likely to become embrittled.

[0023] <6> A method for producing a powder according to an embodiment of the present disclosure is a method for producing a powder containing a plurality of iron carbonate particles, ２ The method includes a step A of preparing a first raw material containing a carbonate, a step B of preparing a second raw material containing a carbonate, and a step C of mixing the first raw material with the second raw material. One of the first raw material and the second raw material is a powder raw material, and the other is a solution raw material.

[0024] According to the powder manufacturing method described above, when the first raw material and the second raw material are mixed, iron carbonate particles are generated from divalent iron ions and carbonate ions. Here, as shown in Test Example 1 described later, when one of the first raw material and the second raw material is a powder raw material and the other is a solution raw material, the generated iron carbonate particles have a spherical shape. Unlike the powder manufacturing method disclosed herein, when both the first raw material and the second raw material are solution raw materials, the generated iron carbonate particles have a prismatic shape.

[0025] <7> In the step C of the powder manufacturing method described in <6> above, the second raw material, which is the powder raw material, may be mixed with the first raw material, which is the solution raw material.

[0026] As shown in Test Example 1 below, FeCl ２ By mixing the first raw material, which is a solution of the above, with the second raw material, which is a powder of carbonate, iron carbonate particles are efficiently produced. Therefore, the proportion of iron carbonate particles in the powder produced by the powder production method of the present disclosure tends to be high.

[0027] <8> In the method for producing a powder according to the above <6> or <7>, the carbonate is NaHCO ３ It may be.

[0028] NaHCO ３ That is, sodium bicarbonate contributes to the efficient production of iron carbonate particles, and therefore the powder obtained by the powder production method of the present disclosure tends to have a high proportion of iron carbonate particles.

[0029] <9> In the method for producing a powder according to any one of <6> to <8> above, the mixed solution of the first raw material and the second raw material in the step C may contain ascorbic acid.

[0030] The addition of ascorbic acid to the mixed solution tends to promote the production of iron carbonate particles. Ascorbic acid may be added to the raw material solution before mixing, or may be added to the mixed solution.

[0031] <10> In the method for producing a powder according to any one of <6> to <9> above, the temperature of the mixed solution of the first raw material and the second raw material in the step C may be 40°C or higher and 70°C or lower.

[0032] When the temperature of the mixed solution is 40° C. or higher and 70° C. or lower, the production of iron carbonate particles is easily promoted.

[0033] [Details of the embodiments of the present disclosure] Specific examples of the powder of the present disclosure, a method for producing the powder, and a composite material containing the powder will be described below with reference to the drawings. The same reference numerals in the figures indicate the same or corresponding parts. The sizes of the components shown in each drawing are expressed for the purpose of clarifying the description and do not necessarily represent the actual dimensions.

[0034] <Embodiment 1> The powder in this embodiment is a powder containing a plurality of iron carbonate particles. In this embodiment, a method for producing the powder will first be described. Next, the powder produced by the powder production method of this example and a composite material containing the powder will be described.

[0035] <<Method for Producing Powder>> As shown in the flowchart of Figure 1, the method for producing powder in this example includes step A of preparing a first raw material, step B of preparing a second raw material, and step C of mixing the first raw material and the second raw material. One of the features of this method for producing powder is that one of the first raw material and the second raw material is a powder raw material, and the other is a solution raw material. Each step will be described in detail below.

[0036] [Step A] The first raw material in step A is FeCl ２ Contains FeCl ２ is sometimes written as iron(II) chloride. The valence of the iron in the first raw material is divalent. Trivalent iron is not suitable for the iron in the first raw material.

[0037] The first raw material may be a powder raw material or a solution raw material. The first raw material made of a powder raw material is iron (II) chloride powder. The first raw material made of a solution raw material is obtained by dissolving iron (II) chloride powder in a solvent. The solvent is, for example, water. The first raw material made of a solution raw material has divalent iron ions dissolved therein. The FeCl per 1 L (liter) of solvent in the first raw material made of a solution raw material is ２ The content ratio is, for example, 0.12 mol / L (moles per liter) or more and 4.8 mol / L or less.

[0038] [Step B] The second raw material in step B contains a carbonate. The carbonate contains carbonate ions (CO ３ ２－ The carbonate is, for example, sodium bicarbonate (NaHCO ３ ), or sodium sesquicarbonate. Sodium bicarbonate is also called baking soda. Sodium sesquicarbonate is sodium carbonate (Na ２ CO ３ Sodium bicarbonate is a compound in which iron carbonate and sodium bicarbonate coexist as a double salt. Sodium bicarbonate is more likely to increase the amount of iron carbonate particles produced than sodium sesquicarbonate.

[0039] The second raw material may be a powder raw material or a solution raw material. A second raw material made of a powder raw material is a carbonate powder. A second raw material made of a solution raw material is obtained by dissolving carbonate powder in a solvent. The solvent is, for example, water. The carbonate content in the second raw material that is a solution raw material is, for example, 0.12 mol / L or more and 4.8 mol / L or less. However, when the first raw material is made of a powder raw material, the second raw material is a solution raw material. When the first raw material is made of a solution raw material, the second raw material is a powder raw material.

[0040] Step A and step B are independent of each other, and it does not matter which step is performed first.

[0041] [Step C] In step C, the first raw material and the second raw material are mixed. Here, one of the first raw material and the second raw material is a solution raw material, and the other is a powder raw material. Therefore, in the mixing in step C, the powder raw material is mixed with the solution raw material. ２＋ and one molecule of CO ３ ２－ Thus, in step C, the first raw material and the second raw material are, for example, FeCl ２ The number of moles of the carbonate is approximately equal to the number of moles of the carbonate.

[0042] The mixed solution in step C may contain ascorbic acid. Ascorbic acid may be added to the liquid raw materials before mixing, or may be added to the mixed solution. The inclusion of ascorbic acid in the mixed solution tends to promote the production of iron carbonate particles. The content of ascorbic acid in the mixed solution is, for example, 0.005 mol / L or more and 0.2 mol / L or less. The content of ascorbic acid may also be 0.01 mol / L or more and 0.1 mol / L or less.

[0043] If the temperature of the mixed solution in step C is room temperature or higher, the production of iron carbonate particles is likely to be promoted. The temperature of the solution raw material is, for example, 40°C or higher and 70°C or lower. If the temperature of the mixed solution is maintained at 40°C or higher and 70°C or lower while the first raw material and the second raw material are being mixed, the production of iron carbonate particles is further promoted. The temperature of the mixed solution may be 50°C or higher and 60°C or lower. When the temperature of the mixed solution is 50°C or higher and 60°C or lower, a large amount of iron carbonate particles is likely to be produced, and substances other than iron carbonate particles are unlikely to be produced.

[0044] The mixing time for mixing the first raw material and the second raw material in step C is, for example, 0.05 hours or more and 96 hours or less. If the mixing time is 0.05 hours or more, a sufficient amount of iron carbonate particles is likely to be produced. The amount of iron carbonate particles produced tends to saturate over time. If the mixing time is 96 hours or less, a powder containing iron carbonate particles can be efficiently produced. The mixing time may be 0.1 hours or more and 48 hours or less.

[0045] Powder 1 produced by the above-described powder production method will be described with reference to the electron microscope photographs shown in Figures 2 to 4. The electron microscope photographs in Figures 2 and 3 were taken of powder of Sample No. 8 in Test Example 1, which will be described later. The magnification in Figure 2 is 10,000 times, and the magnification in Figure 3 is 30,000 times. The electron microscope photograph in Figure 4 was taken of powder of Sample No. 13 in Test Example 1, which will be described later. The magnification in Figure 4 is 30,000 times.

[0046] As shown in Figures 2 and 3, powder 1 produced by the above-described powder production method contains a plurality of iron carbonate particles 2. The iron carbonate particles 2 are primary particles. The plurality of iron carbonate particles 2 aggregate to form secondary particles. The secondary particles can be separated into individual iron carbonate particles 2 by crushing or the like. As shown in the electron microscope photograph in Figure 4, depending on the conditions of the powder production method, powder 1 can contain FeO(OH) particles 3 in addition to the iron carbonate particles 2. The particle size of the FeO(OH) particles 3 tends to be larger than the particle size of the iron carbonate particles 2.

[0047] When the above powder 1 is incorporated into a composite material 4 (described later), the mechanical strength of the composite material 4 is more easily improved when the powder 1 contains fewer FeO(OH) particles 3 and more iron carbonate particles 2. In other words, the greater the content of iron carbonate particles 2 in the powder 1, the more easily the mechanical strength of the composite material 4 is improved. When the total mass of the powder 1 is taken as 100 mass%, the content of iron carbonate particles 2 is, for example, 50 mass% or more. The content of iron carbonate particles 2 in the powder 1 may be 60 mass% or more, 70 mass% or more, 80 mass% or more, 90 mass% or more, or 95 mass% or more. Of course, the content of iron carbonate particles 2 in the powder 1 may be 100 mass%.

[0048] The composition of the iron carbonate particles 2 can be determined by, for example, X-ray diffraction in accordance with JIS K 0131:1996.

[0049] The shape of the iron carbonate particles 2 is spherical. The spherical shape of the iron carbonate particles 2 can be easily confirmed from the electron microscope photograph. For comparison, an electron microscope photograph of powder 7 containing non-spherical iron carbonate particles 8 is shown in Figure 5. The electron microscope photograph in Figure 5 was taken of powder 7 of sample No. 5 in Test Example 1, which will be described later. The iron carbonate particles 8 contained in this powder 7 are in the shape of a prism with corners, and are clearly not spherical.

[0050] The spherical shape of the iron carbonate particles 2 may be quantitatively determined by the circularity. The circularity can be determined, for example, by analyzing a photograph of the iron carbonate particles 2 taken with an electron microscope and identifying the outline of the iron carbonate particles 2. The formula for calculating the circularity is 4π×S / L ２ where S is the area surrounded by the contour line, and L is the length of the contour line. For example, if the average circularity of the plurality of iron carbonate particles 2 is 0.80 or more, it can be determined that the iron carbonate particles 2 contained in the powder 1 are spherical. The average circularity is the average value of the circularities of the plurality of iron carbonate particles 2. The modulus for determining the average circularity is 10 or more. The average circularity may be 0.82 or more, or 0.84 or more.

[0051] The average particle size of the iron carbonate particles 2 is 10 nm or more and 1 μm or less. The average particle size in the present disclosure is the median diameter (D50) that is the value at which the volume-based distribution is 50% as calculated in accordance with JIS Z 8819-2:2001.

[0052] <<Composite Material>> The above-described powder 1 can be used as a raw material for a composite material. As shown in FIG. 6 , the composite material 4 includes a resin 5 and the powder 1 dispersed in the resin 5. The resin material forming the resin 5 is not particularly limited. For example, the resin material may be a thermoplastic resin or a thermosetting resin. The resin 5 may be formed from one type of resin material or multiple types of resin materials.

[0053] Examples of thermoplastic resins include polyethylene, polypropylene, polystyrene, acrylonitrile-butadiene-styrene resin, acrylonitrile-styrene resin, polyvinyl chloride, polymethyl methacrylic resin, polyvinyl alcohol, polyvinylidene chloride, polyethylene terephthalate, polybutylene terephthalate, cycloolefin polymer, polyamide, polyacetal, polycarbonate, polyphenylene ether, fluororesin, polysulfone, polyethersulfone, polyphenylene sulfide, polyarylate, polyamideimide, polyetherimide, polyetheretherketone, thermoplastic polyimide, liquid crystal polymer, and thermoplastic polyurethane.

[0054] The thermosetting resin is, for example, an epoxy resin, a melamine resin, an acrylic resin, a phenolic resin, a silicone resin, a thermosetting polyimide, a urea resin, an unsaturated polyester resin, an alkyd resin, or a thermosetting polyurethane.

[0055] When the total mass of the composite material 4 is taken as 100 mass%, the content of powder 1 contained in the composite material 4 is, for example, 20 mass% or more and 80 mass% or less. If the content of powder 1 in the composite material 4 is 20 mass% or more, the strength of the composite material 4 is likely to be improved. If the content of powder 1 in the composite material 4 is 80 mass% or less, the powder 1 and resin 5 are easily mixed. Furthermore, if the content is 80 mass% or less, the iron carbonate particles 2 are less likely to fall off from the composite material 4, and the composite material 4 is less likely to become embrittled. Furthermore, if the content is 50 mass% or less, the powder 1 and resin 5 are easily mixed, and the strength of the composite material 4 is more likely to be improved. The iron carbonate particles 2 impart flame retardancy, heat dissipation properties, UV blocking properties, etc. to the composite material 4. The content of the powder 1 in the composite material 4 may be 30% by mass or more and 60% by mass or less, 40% by mass or more and 60% by mass or less, or 40% by mass or more and 50% by mass or less.

[0056] The composite material 4 containing the spherical iron carbonate particles 2 is unlikely to exhibit anisotropy. Therefore, the composite material 4 of this example can be used in a variety of products. Examples of uses for the composite material 4 include exterior parts for vehicles, parts of gear parts, parts of pumps, and parts of reducers. The composite material 4 may also be used as an insulating coating for electronic parts or as a paint. Additionally, the composite material 4 may also be used as a raw material for part of the negative electrode of a lithium-ion battery.

[0057] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to the following examples.

[0058] <Test Example 1> In Test Example 1, powders containing iron carbonate particles were produced using several different methods, resulting in Samples 1 to 15. The content and shape of the iron carbonate particles in each sample were then investigated. Each of the production methods for the powder samples included the steps of preparing a first raw material, preparing a second raw material, mixing the first raw material and the second raw material, and recovering the powder.

[0059] <<Step of Preparing the First Raw Material>> In this step, iron chloride powder consisting of iron (II) chloride powder or iron (III) chloride powder was prepared to produce the first raw material. When producing a sample powder using a powdered first raw material, the iron chloride powder itself was used as the first raw material. When producing a sample powder using a solution-like first raw material, 100 milliliters of a solution-like raw material prepared by dissolving iron chloride powder in water was used as the first raw material. The molar number of iron chloride in both the powder-like raw material and the solution-like raw material was 0.24. The composition of the first raw material is shown in Figure 7.

[0060] <<Step of Preparing the Second Raw Material>> In this step, carbonate powder consisting of sodium bicarbonate powder, sodium sesquicarbonate powder, or a mixed powder of sodium bicarbonate powder and sodium sesquicarbonate powder was prepared to produce the second raw material. When producing the sample powder using the powdered second raw material, the carbonate powder itself was used as the second raw material. When producing the sample powder using the solution-like second raw material, 100 milliliters of solution-like raw material produced by dissolving the carbonate powder in water was used as the second raw material. The molar number of carbonate in both the powder-like raw material and the solution-like raw material was 0.24. The composition of the second raw material is shown in Figure 7.

[0061] <<Step of Mixing First Raw Material and Second Raw Material>> In this step, a mixed solution was produced by mixing any of the first raw materials prepared in the step of preparing the first raw material with any of the second raw materials prepared in the step of preparing the second raw material. The mixing patterns were mixing of the first raw material in solution with the second raw material in powder form, mixing of the first raw material in powder form with the second raw material in solution form, or mixing of the first raw material in solution with the second raw material in solution form. The mixing was performed using a stirrer. The mixing time was 2 hours. In the mixing step, oxygen was not excluded from the mixed solution. In other words, no equipment was required to keep the mixed solution airtight in the mixing step.

[0062] In the production of some samples, ascorbic acid was added to the liquid raw material before adding the powdered raw material. The content of ascorbic acid in the mixed solution was 0.0068 mol. Furthermore, in the production of some samples, the mixed solution was heated to change its temperature. The temperature of the mixed solution was room temperature, 40°C, 50°C, 60°C, or 70°C. The room temperature was 25°C.

[0063] <<Powder Recovery Step>> The mixed solution was mixed for 2 hours, and a sufficient amount of precipitate was produced in the mixed solution. The mixed solution containing the precipitate was filtered, and the precipitate was recovered. The recovered precipitate was washed multiple times with an aqueous ascorbic acid solution. This washing was an operation to remove sodium chloride from the precipitate. The ascorbic acid content in the aqueous ascorbic acid solution was 0.2 w / v% (weight per volume percent). The washed precipitate was air-dried to obtain powder for each sample.

[0064] <<Powder Analysis>> The powder composition of each sample was investigated, as well as the shape of the particles that make up the powder. The powder composition was measured by quantitative analysis using X-ray diffraction in accordance with JIS-K-0131:1996. Each particle contained in the powder was FeCO ３ particles, or FeO(OH) particles. ３ The content ratios of iron(II) chloride and iron(III) chloride are shown in Figure 7. These content ratios are based on the total mass of the powder, which is 100% by mass. Figure 7 also shows information on the first raw material, the second raw material, and the mixing conditions used to produce each sample. The "State" column in Figure 7 indicates whether the first raw material and the second raw material were solutions or powders. The "mass %" in the "First Raw Material" column is the ratio when the total mass of iron(II) chloride and iron(III) chloride is 100% by mass. 100% by mass of iron(II) chloride means that the first raw material does not contain iron(III) chloride. Similarly, the "mass %" in the "Second Raw Material" column is the ratio when the total mass of baking soda and sodium sesquicarbonate is 100% by mass.

[0065] Electron microscope photographs of the powder of each sample were taken to confirm the particle shape. The particle shape was either a prismatic shape with corners or a spherical shape without corners. The results of the particle shape are shown in Figure 7. The particle shape was determined by visually inspecting the electron microscope photographs.

[0066] The average particle size of the powder 1 of each sample was measured based on JIS Z 8819-2: 2001. The average particle size of all the powders 1 was in the range of 10 nm or more and 1 μm or less.

[0067] <<Results>> As shown in Samples No. 1, 3, and 5 to 15 in Figure 7, it was found that iron carbonate particles were generated when the valence of Fe contained in the first raw material was divalent. On the other hand, as shown in Samples No. 2 and 4, when the valence of Fe contained in the first raw material was trivalent, iron carbonate particles were not generated. These results revealed that the valence of Fe contained in the first raw material has a significant impact on the generation of iron carbonate particles.

[0068] As shown in Samples No. 6 to 15 in Figure 7, when one of the first and second raw materials was a powder and the other was a solution, the iron carbonate particles contained in the powder were spherical. As an example, electron microscope photographs of Powder 1 for Sample No. 8 are shown in Figures 2 and 3. As is clear from these electron microscope photographs, all of the iron carbonate particles 2 contained in Powder 1 were fine and spherical. Furthermore, an electron microscope photograph of Powder 1 for Sample No. 13 is shown in Figure 4. Powder 1 for Sample No. 13 contained a mixture of spherical iron carbonate particles 2 and spherical FeO(OH) particles 3. The iron chloride used in producing Sample No. 13 was divalent, and when the first and second raw materials were mixed, iron(II) hydroxide was generated depending on the conditions. Iron(II) hydroxide readily converted to iron(III) oxide hydroxide in the presence of oxygen. Therefore, Powder 1 for Sample No. 13 contained FeO(OH) particles 3. The particle size of FeO(OH) particles 3 was clearly larger than that of iron carbonate particles 2. On the other hand, as shown in Samples No. 1, 3, and 5, when both the first and second raw materials were solution-like raw materials, the iron carbonate particles contained in the powder were prismatic. As an example, FIG. 5 shows an electron microscope photograph of Powder 7 of Sample No. 5. As is clear from this electron microscope photograph, all of the iron carbonate particles 8 contained in Powder 1 were prismatic. A comparison of FIGS. 3 and 5, and a comparison of FIGS. 4 and 5, which are taken at the same magnification, reveals that the prismatic iron carbonate particles 8 tend to grow larger than the spherical iron carbonate particles 2. These results reveal that mixing the solution-like raw material with the powder-like raw material during mixing of the first and second raw materials significantly affects the shape of the iron carbonate particles.

[0069] A comparison of sample No. 6, in which the mixed solution did not contain ascorbic acid, with sample No. 7, in which the mixed solution contained ascorbic acid, revealed that the inclusion of ascorbic acid in the mixed solution dramatically increased the amount of iron carbonate particles produced.

[0070] A comparison of Samples No. 7, 8, 13, 14, and 15, which had different mixed solution temperatures, revealed that when the mixed solution temperature was 40° C. or higher and 70° C. or lower, the amount of iron carbonate particles produced was greater than when the mixed solution temperature was lower than 40° C. In particular, when the mixed solution temperature was 50° C. or higher and 60° C. or lower, the iron carbonate particle content in the powder was 100% by mass.

[0071] A comparison of Samples No. 8, 9, and 10, which contain different types of carbonate, revealed that sodium bicarbonate is more suitable as a carbonate than sodium sesquicarbonate. Sample No. 8, which contained only sodium bicarbonate as the carbonate, produced the greatest amount of iron carbonate particles, while Sample No. 10, which contained only sodium sesquicarbonate as the carbonate, produced the least amount of iron carbonate particles.

[0072] A comparison between Sample No. 7 and Sample No. 11, and a comparison between Sample No. 8 and Sample No. 12, revealed that mixing the first raw material in solution with the second raw material in powder form produced a larger amount of iron carbonate particles than mixing the first raw material in powder form with the second raw material in solution form.

[0073] <Test Example 2> In Test Example 2, a test piece of Sample No. 20 consisting of only Resin 5 was prepared, and test pieces of Samples 21 to 24 consisting of Composite Material 4 with different contents of Powder 1 were prepared. Then, by comparing the physical properties of the test pieces of Samples 20 to 24, the influence of the content of Powder 1 in Composite Material 4 on the properties of Composite Material 4 was investigated.

[0074] <<Sample No. 20>> The test piece of Sample No. 20 was made only of polypropylene (hereinafter, PP). This PP was manufactured by Japan Polypropylene Corporation.

[0075] <Samples No. 21 to 24> Samples No. 21 to 24 were test pieces formed of composite material 4 containing resin 5 and powder 1. The content of powder 1 was 30 mass%, 40 mass%, 50 mass%, or 60 mass%, relative to 100 mass% of composite material 4. Resin 5 was the same as the PP constituting sample No. 20. Powder 1 was the powder of sample No. 8 in Test Example 1.

[0076] In preparing the test pieces of Sample No. 21 to Sample No. 24, Resin 5 and Powder 1 could be kneaded together regardless of the content ratio of Powder 1. The test pieces of Sample No. 21 to Sample No. 24 were prepared by molding the kneaded mixture of Resin 5 and Powder 1 using an electric 110-ton free-blend prototype machine.

[0077] Measurement of Physical Properties: Samples No. 20 to No. 24 were measured for mold shrinkage, specific gravity, tensile strength, tensile strain, tensile modulus, flexural strength, flexural modulus, hardness, and Charpy impact strength. Mold shrinkage was calculated by measuring the mold dimensions and the dimensions of the molded article after shrinkage, and then calculating the ratio of the measured values. Specific gravity was measured according to a method conforming to JIS K 7112. Tensile strength, tensile strain, and tensile modulus were measured according to a method conforming to JIS K 7161 using a precision universal testing machine, Autograph AG-X, manufactured by Shimadzu Corporation. Flexural strength and flexural modulus were measured according to a method conforming to JIS K 7171 using a precision universal testing machine, Autograph AG-X, manufactured by Shimadzu Corporation. Hardness was measured according to a method conforming to JIS K 7215 using an Asker Rubber Hardness Tester, Type D, Durometer, manufactured by Kobunshi Keiki Co., Ltd. The Charpy impact strength was measured using a Charpy impact tester No. 556 manufactured by Toyo Seiki Seisakusho, Ltd., in accordance with the method specified in JIS K7111.

[0078] The measurement results are shown in Figure 8. In Figure 8, the measurement results except for the Charpy impact strength are shown as a percentage, with the value of sample No. 20 being 1. The measurement results of the Charpy impact strength are shown as "no break" or numerical values. "No break" means that no break occurred under the test conditions of the Charpy impact test. The numerical values ​​are the measured values ​​when break occurred in the Charpy impact test. The unit of Charpy impact strength is KJ / m ２ (kilojoules per square meter).

[0079] <<Results>> The following was learned from the results in Fig. 8: In the following description, "the content ratio of powder 1 in composite material 4" will be simply referred to as "the content ratio of powder 1."

[0080] 8, the higher the content of Powder 1, the lower the molding shrinkage of Composite Material 4. Therefore, it is considered that by increasing the content of Powder 1, a molded body made of Composite Material 4 can be manufactured with good dimensional accuracy.

[0081] The tensile strain decreased as the content of Powder 1 increased. Furthermore, the tensile modulus, flexural modulus, and Shore D hardness of Composite Material 4 increased as the content of Powder 1 increased. This is thought to indicate that Composite Material 4 becomes harder as the content of Powder 1 increases.

[0082] On the other hand, as the content of Powder 1 increased, the tensile strength and flexural strength of Composite Material 4 increased, but when the content of Powder 1 exceeded 50 mass%, the tensile strength and flexural strength of Composite Material 4 tended to decrease. Furthermore, test pieces with a content of Powder 1 of 50 mass% or less did not break in the Charpy impact test. On the other hand, test pieces with a content of Powder 1 exceeding 50 mass% broke in the Charpy impact test. This is thought to indicate that as the content of Powder 1 in Composite Material 4 increased, Composite Material 4 became harder but also more brittle.

[0083] Although the case where resin 5 is PP has been described in Test Example 2, resin 5 may be a resin other than PP. Even when a resin other than PP is used, it is considered that the same results as in Test Example 2 can be obtained regarding the effect of the content ratio of powder 1 on the physical properties of composite material 4.

[0084] The embodiments and examples disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0085] 1 Powder, 2 Iron carbonate particles, 3 FeO(OH) particles, 4 Composite material, 5 Resin, 7 Powder, 8 Iron carbonate particles.

Claims

1. A powder comprising a plurality of iron carbonate particles, the iron carbonate particles having an average particle size of 10 nm or more and 1 μm or less, and the iron carbonate particles being spherical in shape.

2. The powder according to claim 1, wherein the iron carbonate particles have an average circularity of 0.80 or more.

3. The powder according to claim 1 or claim 2, wherein the content of the plurality of iron carbonate particles is 50% by mass or more when the total mass is 100% by mass.

4. A composite material comprising: a resin; and the powder according to any one of claims 1 to 3 dispersed in the resin.

5. A composite material according to claim 4, wherein the content of said powder is 20% by mass or more and 80% by mass or less when the total mass is 100% by mass.

6. A method for producing a powder containing a plurality of iron carbonate particles, comprising: ２ a step A of preparing a first raw material containing a carbonate; a step B of preparing a second raw material containing a carbonate; and a step C of mixing the first raw material and the second raw material, wherein one of the first raw material and the second raw material is a powder raw material and the other is a solution raw material.

7. The method for producing a powder according to claim 6, wherein in step C, the first raw material, which is the liquid raw material, is mixed with the second raw material, which is the powder raw material.

8. The carbonate is NaHCO ３ The method for producing a powder according to claim 6 or 7, wherein 9. A method for producing a powder according to any one of claims 6 to 8, wherein the mixed solution of the first raw material and the second raw material in step C contains ascorbic acid.

10. A method for producing a powder according to any one of claims 6 to 9, wherein the temperature of the mixed solution of the first raw material and the second raw material in step C is 40°C or higher and 70°C or lower.

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