JP2023120508A - Powder and powder manufacturing method - Google Patents

Abstract

To provide a powder or the like that reduces abnormalities detected when a product thereof is analyzed.SOLUTION: According to one aspect of the present invention, a powder containing ZnO, Al2O3 and SiO2 is provided. In the powder, the amount of Zr contained in the powder is 10 ppm or less with respect to the total amount of the powder.SELECTED DRAWING: None

Description

The present invention relates to powders and methods of making powders.

In general, powdery fillers are used for the purpose of improving physical properties or functions of substrates such as glass materials and resin materials. For example, amorphous silica has a small thermal expansion coefficient of about 0.5×10 ⁻⁶ /° C. and is relatively easily available, so it is used as a filler for controlling the thermal expansion coefficient of substrates. . However, when adding it to a base material used for bonding, sealing, sealing, etc., in order to match the thermal expansion coefficient of the filler with that of the base material and suppress the generation of thermal stress, A filler with a thermal expansion coefficient even smaller than that of amorphous silica has attracted attention.

Many materials such as zirconium phosphate, zirconium tungstate, and manganese nitride are known as materials having a thermal expansion coefficient smaller than that of amorphous silica. However, the specific gravity of these materials is large, and the resin materials after blending become heavy, so that they are not generally used for electronic parts and the like. Therefore, materials that are lightweight and have a small coefficient of thermal expansion are actively being developed.

For example, Patent Document 1 discloses _a powder containing three components of ZnO, _Al2O3 and _SiO2 . It is disclosed that such a powder, when blended in a resin base material, is excellent in reducing the coefficient of thermal expansion of the base material.

Related to this, the technique disclosed in Non-Patent Document 1 is also known. According to this document, by allowing ZrO ₂ to function as a nucleating agent for the three components of ZnO, Al ₂ O ₃ and SiO ₂ , it is shown that the crystallization behavior can be adjusted to obtain a desired glass component. ing.

International Publication No. 2019/177112 pamphlet

"Materials" (Journal of the Society of Materials Science, Japan), Vol. 61, No. 6, pp. 509-513, June 2012

However, as a result of investigations by the present inventors, it was found that, when the powder in the prior art is included in a resin or the like, there is a component observed as a foreign substance at the stage of quality inspection or the like.
Here, it can be said that it is desirable to be able to prevent such a phenomenon from the viewpoint of smoothly expanding the powder to various materials.

In view of the above circumstances, the present invention provides a powder or the like that suppresses detection of abnormalities during product analysis.

According to one aspect of the invention there is provided _a powder comprising ZnO, _Al2O3 and _SiO2 . In this powder, the Zr content in the powder is 10 ppm or less with respect to the total amount of the powder.

The present invention may be provided in each aspect described below.
The powder, wherein the U content in the powder is 10 ppb or less with respect to the total amount of the powder.
The powder, wherein the powder has an average circularity of 0.6 or more.
Among the above-mentioned powders, the powder used by blending in glass or resin.
In the method for producing the powder, preparing a raw material mixture containing ZnO, Al ₂ O ₃ and SiO ₂ , melting the raw material mixture, cooling the molten raw material mixture, and producing a raw glass and pulverizing the raw glass.
In the method for producing the powder, the raw material glass is pulverized in a stamp mill.
Of course, this is not the only case.

ADVANTAGE OF THE INVENTION According to this invention, the powder etc. which can suppress the abnormality detection at the time of product analysis can be provided.

Embodiments of the present invention will be described below. The present invention is not limited to the following embodiments, and each component shown in the following embodiments can be combined with each other.

<powder>
The powder according to this embodiment is a powder containing ZnO, Al ₂ O ₃ and SiO ₂ . Also, the Zr content in the powder is 10 ppm or less with respect to the total amount of the powder.

As described above, as a result of investigations by the present inventors, it has been found that, when the powder in the prior art is included in a resin or the like, there is a component that is observed as a foreign matter at the stage of quality inspection or the like. More specifically, if the content of Zr (zirconium) is increased with respect to the powder containing ZnO, Al ₂ O ₃ and SiO ₂ , the quality inspection stage when the powder is included in resin etc. , it was found that there are cases where it is observed as a foreign substance.

Specifically, when Zr is contained excessively, the X-ray transparency is lowered (the X-ray opacity is improved), which may impede the accuracy of the foreign matter inspection for the material containing the powder. In other words, there is a concern that foreign matter of an element lighter than Zr may be overlooked since the inspection object contains Zr, which is highly opaque to X-rays, during foreign matter inspection.

There are various possible causes for such Zr contamination, but in Patent Document 1, a ball mill is used for the raw material powder, and zirconia balls are sometimes used in the same equipment, so Zr is mixed into the powder as a result. Easy to give results. However, the source of this Zr contamination is not limited to the powder pulverization process such as a ball mill, but may be caused by raw materials or by other devices.

In this specification, the "Zr content" is a value measured by inductively coupled plasma atomic emission spectrometry under the following measurement conditions, and includes ionic zirconium compounds, zirconium oxide, and metallic zirconium.
<Measurement conditions>
First, 0.2 g of powder is weighed into a platinum crucible and dried on a hot plate at 100° C. using hydrofluoric acid and sulfuric acid. After that, after white smoke treatment on a hot plate at 220° C., ultrapure water and nitric acid are added and dissolved by heating to prepare a measurement solution. The Zr content of this measurement solution is determined using an ICP emission spectrometer (for example, 5110VDV manufactured by Agilent).

The Zr content in the powder is preferably 8 ppm or less, more preferably 5 ppm or less, even more preferably 3 ppm or less, and 1 ppm or less relative to the total amount of the powder. is particularly preferred.
Also, the Zr content contained in the powder may be below the detection limit under the aforementioned measurement conditions.

The powder of this embodiment contains three components, ZnO, _Al2O3 and _{SiO2 .} The content of the three components is ZnO: 17 to 43 mol%, Al ₂ O ₃ : 9 to 20 mol%, and SiO ₂ : 48 to 74 mol%, based on the total content of the three components. is preferred.

The content of ZnO is preferably 17 to 43 mol% based on the total content of the three components, and is more preferable from the viewpoint of further improving the effect of reducing the coefficient of thermal expansion when blended in a resin material or the like. is 20 to 40 mol %, more preferably 22 to 39 mol %, still more preferably 25 to 35 mol %. The content of ZnO is 17 to 40 mol%, 17 to 39 mol%, 17 to 35 mol%, 20 to 43 mol%, 20 to 39 mol%, 20 to 35 mol%, based on the total content of the three components. mol %, 22-43 mol %, 22-40 mol %, 22-35 mol %, 25-43 mol %, 25-40 mol %, or 25-39 mol %.

The content of Al ₂ O ₃ is preferably 9 to 20 mol%, more preferably 10 to 19 mol%, still more preferably 11 to 18 mol%, based on the total content of the three components. is. The content of Al ₂ O ₃ is 9 to 19 mol%, 9 to 18 mol%, 10 to 20 mol%, 10 to 18 mol%, 11 to 20 mol%, based on the total content of the three components. Alternatively, it may be 11 to 19 mol %.

The content of SiO ₂ is preferably 48 to 74 mol%, more preferably 49 to 72 mol%, still more preferably 50 to 70 mol%, based on the total content of the three components. , particularly preferably 50 to 65 mol %. The content of SiO ₂ is 48-65 mol%, 48-64 mol%, 49-63 mol%, 49-62 mol%, or 50-62 mol% based on the total content of the three components. may

The powder may contain ionic impurities, which are unavoidable impurities, in addition to Zr, and the content thereof is not particularly limited. The total content of Li, Na and K as ionic impurities is, for example, 500 mass ppm or less, 450 mass ppm or less, 400 mass ppm or less, 350 mass ppm or less, 300 mass ppm or less, 250 mass ppm or less with respect to the total amount of the powder. mass ppm or less, 200 mass ppm or less, 150 mass ppm or less, 100 mass ppm or less, 90 mass ppm or less, 80 mass ppm or less, 70 mass ppm or less, 60 mass ppm or less, 50 mass ppm or less, 40 mass ppm or less, 30 It is preferably no more than mass ppm, no more than 20 mass ppm, and no more than 10 mass ppm. Since the total content of Li, Na and K is less than the required amount, it is possible to improve moisture resistance reliability and suppress failure of electronic devices when electronic device members are produced using the powder. can. However, the total content of Li, Na and K may be more than 500 ppm by mass with respect to the total amount of the powder. On the other hand, the content of Li is 0 ppm by mass or more with respect to the total amount of the powder (the total content of Li, Na and K is 0 ppm by mass, ie Li, Na and K are not included at all). good.

The content of Li is not particularly limited. mass ppm or less, 150 mass ppm or less, 100 mass ppm or less, 90 mass ppm or less, 80 mass ppm or less, 70 mass ppm or less, 60 mass ppm or less, 50 mass ppm or less, 40 mass ppm or less, 30 mass ppm or less, 20 It is preferably 10 ppm by mass or less, preferably 10 ppm by mass or less. On the other hand, the Li content may be 0 ppm by mass or more relative to the total amount of the powder (including a mode in which the Li content is 0 mass ppm, ie, no Li at all).

The content of Na is not particularly limited, but for example, 500 mass ppm or less, 450 mass ppm or less, 400 mass ppm or less, 350 mass ppm or less, 300 mass ppm or less, 250 mass ppm or less, 200 mass ppm or less with respect to the total amount of the powder mass ppm or less, 150 mass ppm or less, 100 mass ppm or less, 90 mass ppm or less, 80 mass ppm or less, 70 mass ppm or less, 60 mass ppm or less, 50 mass ppm or less, 40 mass ppm or less, 30 mass ppm or less, 20 It is preferably 10 ppm by mass or less, preferably 10 ppm by mass or less. On the other hand, the content of Na may be 0 ppm by mass or more relative to the total amount of the powder (including a mode in which the Na content is 0 mass ppm, ie, no Na at all).

The K content is not particularly limited, but is, for example, 500 mass ppm or less, 450 mass ppm or less, 400 mass ppm or less, 350 mass ppm or less, 300 mass ppm or less, 250 mass ppm or less, 200 mass ppm or less with respect to the total amount of the powder. mass ppm or less, 150 mass ppm or less, 100 mass ppm or less, 90 mass ppm or less, 80 mass ppm or less, 70 mass ppm or less, 60 mass ppm or less, 50 mass ppm or less, 40 mass ppm or less, 30 mass ppm or less, 20 It is preferably 10 ppm by mass or less, preferably 10 ppm by mass or less. On the other hand, the K content may be 0 ppm by mass or more relative to the total amount of the powder (including an embodiment in which the K content is 0 mass ppm, that is, K is not included at all).

The powder can further contain titanium oxide (TiO ₂ ) and the like in addition to ZnO, Al ₂ O ₃ and SiO ₂ . The total content of ZnO, Al ₂ O ₃ and SiO ₂ is not particularly limited. % or more, 95 mol% or more, 96 mol% or more, 97 mol% or more, 98 mol% or more, 99 mol% or more, 99.5 mol% or more, 99.9 mol% or more, 99.95 mol% or more, 99 It is preferably at least 0.99 mol %. Alternatively, the powder may consist only of ZnO, Al ₂ O ₃ and SiO ₂ and unavoidable impurities. The total content of ZnO, Al ₂ O ₃ and SiO ₂ above the required amount allows the coefficient of thermal expansion of such powders to be more negative.

The powder may also contain U (uranium), but preferably the amount is limited. More specifically, the U content in the powder is preferably 10 ppb or less, more preferably 8 ppb or less, even more preferably 5 ppb or less, and 3 ppb or less with respect to the total amount of the powder. is particularly preferred, and 1 ppb or less is particularly preferred.
Moreover, the U content contained in the powder may be below the detection limit under the measurement conditions described above.
In this specification, the "U content" can be measured by inductively coupled plasma mass spectrometry, and specifically, it is a value measured under the following measurement conditions. This "U content" includes ionic uranium compounds, uranium oxide, and uranium metal.
<Measurement conditions>
First, 0.5 g of the powder is weighed into a platinum crucible, heated and dried on a hot plate at 125° C. using hydrofluoric acid and nitric acid, potassium pyrosulfate is added to the residue, and dissolved in nitric acid to obtain a measurement solution. make. The U content of this measurement solution is determined using an ICP mass spectrometer (for example, 7700x manufactured by Agilent).

The powder preferably contains β-quartz solid solution as the crystalline phase. The content of the β-quartz solid solution is not particularly limited. % or more, 67 mass % or more, 70 mass % or more, 71 mass % or more, 72 mass % or more, 73 mass % or more, 74 mass % or more, 75 mass % or more, 76 mass % or more. When the content of the β-quartz solid solution is greater than or equal to the required amount, the coefficient of thermal expansion of the powder can be made more negative. In addition, since the content of the β-quartz solid solution is more than the required amount, it is possible to increase the amount of powder blended (filled amount) in the base material, making it easier to control the coefficient of thermal expansion of the base material. can do. On the other hand, the content of the β-quartz solid solution may be 100% by mass or less. The structure of the β-quartz solid solution contained in the powder can be expressed as xZnO-yAl ₂ O ₃ -zSiO ₂ . Identification of the crystal phase and measurement of the content can be performed by analyzing the XRD pattern obtained by the powder X-ray diffraction method by the Rietveld method.

The powder may further contain an amorphous phase in addition to the β-quartz solid solution phase, and may further contain other crystalline phases. The powder may contain the Willemite phase (Zn ₂ SiO ₄ ) as another crystalline phase. The powder may also contain garnite phase (ZnAl ₂ O ₄ ), mullite phase (Al ₆ Si ₂ O ₁₃ ) and cristobalite phase (SiO ₂ ), among other crystalline phases. However, the total content of these garnite phase (ZnAl ₂ O ₄ ), mullite phase (Al ₆ Si ₂ O ₁₃ ) and cristobalite phase (SiO ₂ ) is not particularly limited, but for example 10 mass with respect to the total amount of powder. % or less, 9 mass % or less, 8 mass % or less, 7 mass % or less, 6 mass % or less, 5 mass % or less, 4 mass % or less, 3 mass % or less, 2 mass % or less, 1 mass % or less, 0. It is preferably 5% by mass or less, 0.2% by mass or less, 0.1% by mass or less, 0.05% by mass or less, 0.02% by mass or less, and 0.01% by mass or less. The garnite phase (ZnAl ₂ O ₄ ), the mullite phase (Al ₆ Si ₂ O ₁₃ ) and the cristobalite phase (SiO ₂ ) have a positive thermal expansion coefficient, and their content should be below the required amount. Therefore, the coefficient of thermal expansion of the powder can be kept large and negative. On the other hand, the total content of garnite phase (ZnAl ₂ O ₄ ), mullite phase (Al ₆ Si ₂ O ₁₃ ) and cristobalite phase (SiO ₂ ) is 0% by mass or more (these crystal phases content is 0% by mass, that is, an aspect that does not contain these crystal phases at all) may be included.

The shape of the powder is not particularly limited, and a spherical shape, a columnar shape, a prismatic shape, or the like can be used, and a spherical shape is preferably used.

Whether or not the powder is spherical can be confirmed by calculating the average circularity of the powder. In this specification, the average circularity is determined as follows. Specifically, the projected area (S) and the projected peripheral length (L) of particles (powder particles) photographed using an electron microscope are obtained, and the circularity is calculated by applying the following formula (1). The average circularity is calculated as the average circularity of 100 randomly selected particles.
Circularity = 4πS/L ² (1)

The average circularity is not particularly limited, but may be, for example, 0.6 or more, 0.65 or more, 0.7 or more, 0.75 or more, 0.8 or more, 0.85 or more, 0.9 or more. preferable. When the average circularity is equal to or greater than the required amount, the rolling resistance of the particles when mixed with the base material is reduced, the viscosity of the base material is reduced, and the fluidity of the base material can be improved. In particular, when the average circularity is 0.90 or more, the fluidity of the base material is further increased, so that the base material can be highly filled with powder, and the coefficient of thermal expansion can be easily reduced. On the other hand, the average circularity may be 1 or less.

Although the average particle diameter is not particularly limited, it is preferably 0.1 μm or more, 0.2 μm or more, 0.5 μm or more, 1 μm or more, or 2 μm or more. On the other hand, the average particle diameter is preferably 100 µm or less, 90 µm or less, 80 µm or less, 70 µm or less, 60 µm or less, and 50 µm or less. The average particle size of the powder is obtained by measuring the particle size distribution with a laser diffraction particle size distribution analyzer, multiplying the calculated particle size value by the relative particle amount (difference volume%), and obtaining the total relative particle amount (100 volume% ) can be obtained.

The coefficient of thermal expansion in the 112 plane direction of the powder is not particularly limited, but is 0 ppm/° C. or less, −0.1 ppm/° C. or less, −0.2 ppm/° C. or less, −0.3 ppm/° C. or less, −0.4 ppm. / ° C. or less, -0.5 ppm / ° C. or less, -0.6 ppm / ° C. or less, -0.7 ppm / ° C. or less, -0.8 ppm / ° C. or less, -0.9 ppm / ° C. or less, -1 ppm / ° C. or less, It is preferably -1.1 ppm/°C or less, -1.2 ppm/°C or less, -1.3 ppm/°C or less, -1.4 ppm/°C or less, or -1.5 ppm/°C or less. Note that the larger the negative coefficient of thermal expansion of the powder, the lower the amount of powder to be added. Therefore, it is better to have something with a more negative coefficient of thermal expansion. Therefore, the lower limit of the coefficient of thermal expansion in the 112 plane direction of the powder is not particularly limited. The coefficient of thermal expansion in the plane direction is measured by the following method. The thermal expansion coefficient of the main phase is analyzed using high temperature X-ray diffraction (high temperature XRD). Here, an angle standard sample (Si) is added to the sample and measured with a converging optical system. Specifically, about 10% by mass of an angle standard sample (Si, NIST SRM 640c) is added to each sample and mixed in a mortar. After that, place the sample on the sample plate, spread the sample with a glass plate so that the surface of the sample and the surface of the sample plate are aligned, and measure at 6 temperature levels (25 to 300°C) (using a concentrated optical system). . The lattice spacing at each temperature is calculated from the obtained diffraction lines derived from the 112 plane and the 203 plane, and the thermal expansion coefficient of the main phase is analyzed.

The coefficient of thermal expansion in the 203 plane direction of the powder is not particularly limited, but is 0 ppm/° C. or less, -0.1 ppm/° C. or less, -0.2 ppm/° C. or less, -0.3 ppm/° C. or less, -0.4 ppm. / ° C. or less, -0.5 ppm / ° C. or less, -0.6 ppm / ° C. or less, -0.7 ppm / ° C. or less, -0.8 ppm / ° C. or less, -0.9 ppm / ° C. or less, -1 ppm / ° C. or less, It is preferably -1.1 ppm/°C or less, -1.2 ppm/°C or less, -1.3 ppm/°C or less, -1.4 ppm/°C or less, or -1.5 ppm/°C or less. Therefore, the lower limit of the coefficient of thermal expansion in the 203 plane direction of the powder is not particularly limited.

<Powder manufacturing method>
A method for producing powder according to the present embodiment will be described below.
The powder manufacturing method of the present embodiment includes preparing a raw material mixture containing ZnO, Al ₂ O ₃ and SiO ₂ (raw material mixture preparation step), melting the raw material mixture (melting step), and melting It includes cooling the raw material mixture to obtain raw glass (raw glass preparation step) and pulverizing the raw glass (pulverizing step).

[Raw material mixture preparation step]
In the raw material mixture preparation step, raw materials are prepared and mixed to prepare a raw material mixture. Raw materials are not particularly limited, but zinc oxide or the like as a Zn source, aluminum oxide or aluminum hydroxide or the like as an Al source, and silicon oxide (α-quartz, cristobalite, amorphous silica, etc.) as a Si source. and can be used.

The blending amount of the raw materials is not particularly limited, but for example, Zn source: 17 to 43 mol%, Al source: 9 to 20 mol%, Si Source: may be 48-74 mol %.

In the raw material mixture preparation step, in addition to the raw materials described above, various additives may be added within a range that does not affect the coefficient of thermal expansion.

In the raw material mixture, the content of ionic impurities is not particularly limited, but is 500 mass ppm or less, 450 mass ppm or less, 400 mass ppm or less, 350 mass ppm or less, 300 mass ppm or less, 250 mass ppm or less, 200 mass ppm. ppm or less, 150 mass ppm or less, 100 mass ppm or less, 0 mass ppm or less, 80 mass ppm or less, 70 mass ppm or less, 60 mass ppm or less, 50 mass ppm or less, 40 mass ppm or less, 30 mass ppm or less, 20 mass ppm ppm or less, preferably 10 mass ppm or less.

The method of mixing the raw materials is not particularly limited as long as it is a method in which alkali metals such as Na, Li or K and other metal elements such as Fe are difficult to mix. A method of mixing with a machine or various mixers can be used.
Also, from the viewpoint of easily reducing the Zr content, it is effective to adopt materials that are less likely to cause contamination for mixing tools and the like.

[Melting process]
Next, the raw material mixture is placed in a container such as a platinum crucible or an alumina crucible, and melted in a heating furnace such as an electric furnace, a high frequency furnace, an image furnace, or a flame burner. The temperature conditions and time for this melting may be appropriately set according to the composition of the raw material mixture.
This melting takes place, for example, in the temperature range of 1000.degree. C. to 1800.degree.

[Raw glass manufacturing process]
The above melt is then removed into air or water and quenched. By doing so, raw material glass can be obtained. The temperature conditions and time for this cooling may be appropriately set according to the composition of the raw material mixture.

[Pulverization process]
Then, powder is obtained by pulverizing the obtained raw material glass. As a method for pulverizing the raw material glass, a method using an agate mortar, a ball mill, a vibrating mill, a stamp mill, a jet mill, a wet jet mill, or the like, which is appropriately set, may be used. Pulverization can be carried out by either dry or wet method. When pulverizing by a wet pulverization method, for example, liquid such as water or alcohol and raw material powder can be mixed and wet pulverization can be performed.
From the viewpoint of easily reducing the Zr content, it is effective to use a material that is less likely to cause contamination for the tools used for this pulverization. For example, it is preferable to pulverize the raw glass using a stamp mill. The portion of the stamp mill that comes into contact with the raw glass may be alumina, for example.

In addition, the powder production method of the present embodiment may subsequently include a spheroidizing step and a crystallization step.

[Spheroidization step]
In the spheroidizing step, the above powder is spheroidized by a powder melting method. The spheroidizing method by powder melting is a method in which raw material powder is put into a chemical flame, thermal plasma, vertical tubular furnace or tower kiln, melted, and spheroidized by its own surface tension.

In the powder melting method, the particle size distribution can be adjusted by adjusting the powder obtained by pulverizing the raw glass or the powder obtained by granulating with a spray dryer or the like so as to have a desired particle size distribution. These powders are introduced into a chemical flame, a thermal plasma, a vertical tubular furnace, a tower kiln, or the like while suppressing agglomeration, and are melted to be spheroidized. Alternatively, a dispersion of powder dispersed in a solvent or the like is prepared, and the liquid raw material is sprayed into a chemical flame, thermal plasma, vertical tubular furnace, tower kiln, or the like using a nozzle or the like to evaporate the dispersion medium. It may be done by melting the powder on top.

Here, in the powder melting method, "chemical flame" refers to flame generated by burning combustible gas with a burner. As the combustible gas, a temperature equal to or higher than the melting point of the powder can be obtained, and natural gas, propane gas, acetylene gas, liquefied petroleum gas (LPG), hydrogen, and the like can be used, for example. Such combustible gas may be used together with combustible gas such as air, oxygen, etc. as a combustion-supporting gas. Conditions such as the size and temperature of the chemical flame can be adjusted by adjusting the size of the burner and the flow rates of the combustible gas and the combustion-supporting gas.

[Crystallization step]
In the crystallization step, the powder is heated at a high temperature to crystallize it. As a device for crystallization, any heating device may be used as long as a desired heating temperature can be obtained.

Although the temperature for heating to crystallize (crystallization temperature) is not particularly limited, it is preferably 750 to 900° C., for example. By setting the heating temperature to the required temperature or higher, the crystallization time can be shortened, and the content of the β-quartz solid solution phase can be increased by achieving sufficient crystallization. Therefore, the coefficient of thermal expansion of the base material containing the powder can be further reduced. On the other hand, since the crystallization temperature is below the required temperature, crystal phases other than the β-quartz solid solution phase, such as garnite phase, cristobalite phase, willemite phase, etc., are less likely to form, and the thermal expansion coefficient of the base material containing the powder can be further reduced.

The heating time (crystallization time) is not particularly limited, but is preferably 1 to 24 hours, for example. When the heating time is equal to or longer than the required time, crystallization into the β-quartz solid solution phase is sufficiently performed, and the coefficient of thermal expansion of the powder-blended base material can be further reduced. Since the heating time is equal to or less than the required time, the cost required for producing the powder can be suppressed.

A powder that has undergone a crystallization step may be an aggregate in which a plurality of particles are aggregated. The aggregate itself may be used as a powder, but if necessary, the aggregate may be pulverized and powdered. The method for crushing aggregates is not particularly limited, but the same method as the above-described crushing step can be used. The pulverization may be performed dry, or may be performed wet by mixing with a liquid such as water or alcohol. In wet pulverization, the powder of the present embodiment is obtained by drying after pulverization. Although the drying method is not particularly limited, for example, heat drying, vacuum drying, freeze drying, supercritical carbon dioxide drying, and the like can be used.

In another embodiment, the powder manufacturing method may further include a step of classifying the powder so as to obtain a desired average particle size, a washing step, and a surface treatment step using a coupling agent.
This classifying step can be carried out, for example, both after the aforementioned pulverization step and after the crystallization step. In this step, the powder is sieved, for example, to the desired particle size.
In the washing step, the powder is washed with water or an organic solvent. The water or organic solvent may contain an acid such as acetic acid or a base such as ammonia. Note that this washing step is performed after, for example, the spheroidizing step.
By applying the surface treatment, it is possible to further increase the blending amount (filling amount) to the base material. A silane coupling agent, a titanate coupling agent, an aluminate-based coupling agent, or the like can be used as the coupling agent used for the surface treatment.

Moreover, the powder according to the present embodiment can be used by mixing with powder having a composition different from that of the powder (for example, silica, alumina, etc.).

<Use of powder>
Further, in one example, the powder according to the present embodiment is used as it is or mixed with powder having a different composition as described above and blended in glass or resin.

The glass used as the base material is not particularly limited, but PbO--B ₂ O ₃ --ZnO system, PbO--B ₂ O ₃ --Bi ₂ O ₃ system, PbO--V ₂ O ₅ --TeO ₂ system, SiO ₂ -ZnO-M ¹² O system (M ₁₂ O is an alkali metal oxide ⁾ , SiO ₂ -B ₂ O _{3 -M} ¹² O system, or SiO ₂ -B ₂ O _{3 -M 2 O} system (M ₂ A glass having a composition such that O is an alkaline earth metal oxide can be used.

The base resin is not particularly limited. Butylene terephthalate, polyester (polyethylene terephthalate, etc.), polyphenylene sulfide, wholly aromatic polyester, polysulfone, liquid crystal polymer, polyethersulfone, polycarbonate, maleimide modified resin, ABS (acrylonitrile-butadiene-styrene) resin, AAS (acrylonitrile-acrylic rubber) styrene) resins, AES (acrylonitrile-ethylene-propylene-diene rubber-styrene) resins, and mixtures of these resins can be used.

The amount (filling amount) of the powder in the base material is not particularly limited, and may be adjusted according to the coefficient of thermal expansion after addition of the powder. It is preferably up to 95% by volume, more preferably 40 to 90% by volume.

Since the Zr content in the powder according to the present embodiment is restricted, it is possible to suppress detection of abnormalities during analysis of products such as base materials blended with the powder.

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the examples.

[Example 1]
(Raw material powder preparation process)
As shown in Table 1, ZnO, Al ₂ O ₃ and SiO ₂ were used as raw materials, respectively, and these raw materials were mixed in a vibrating mixer (low frequency resonance acoustic mixer Lab RAM II manufactured by Resodyn). 100 g of this mixture was placed in a platinum crucible and heated in an electric furnace to melt. At this time, the temperature inside the electric furnace during melting was set to 1600° C., and the holding time at 1600° C. was set to 30 minutes. After melting, the raw material glass was obtained by submerging the whole crucible in water and quenching. The raw material glass was collected from the platinum crucible, pulverized in a stamp mill for 15 minutes, and passed through a nylon sieve with an opening of 74 μm to obtain a raw material powder.

(Spheroidization process)
The obtained raw material powder was put into a high-temperature flame formed by LPG and oxygen gas using a carrier gas (oxygen), and spheroidized by a powder melting method.

(Crystallization step)
After pulverizing the powder after the spheroidization treatment, it was placed in an alumina crucible, and in an air atmosphere, using an electric furnace, the temperature inside the electric furnace during crystallization was set to 800 ° C., and the holding time at 800 ° C. was set to 24 hours. Crystallized. Thus, a powder according to Example 1 was obtained.

[Examples 2 to 4]
Powders of Examples 2 to 5 were obtained in the same manner as in Example 1 in the crystallization process, with the blending amounts of the raw materials having the compositions shown in Table 1.

[Example 5]
A powder was obtained in the same manner as in Example 1, except that the holding time at 800° C. in the crystallization step was set to 4 hours.

[Comparative Examples 1 to 4]
The blending amount of the raw material is set to the composition shown in Table 1, and further, in the raw material powder preparation process, the raw material powder is melted using alumina zircon bricks and pulverized in a ball mill to obtain a raw material powder, and in the crystallization process, an electric furnace is used. , the furnace temperature of the electric furnace was set to 800° C., and the holding time at 800° C. was set to 24 hours for crystallization to obtain powders according to Comparative Examples 1 to 4.

[Comparative Example 5]
The composition of the raw material is shown in Table 1, and in the powder preparation process, the alumina-zirconium bricks are melted and pulverized in a ball mill to obtain a raw material powder. The temperature was set to 800° C., and the holding time at 800° C. was set for 4 hours to crystallize, and a powder according to Comparative Example 5 was obtained.

Each characteristic of the crystallized powder obtained above was evaluated by the following methods. Each evaluation result is shown in Table 1.

(Elemental analysis)
Analysis of ZnO, Al ₂ O ₃ and SiO ₂ (analysis of content) and quantification of impurities were performed by inductively coupled plasma atomic emission spectrometry. As analyzers, an ICP emission spectrometer (manufactured by Agilent, 5110VDV) and an ICP mass spectrometer (manufactured by Agilent, 7700x) were used. In the analysis of ZnO, Al ₂ O ₃ , and SiO _{2 ,} 10 mg of a sample was weighed in a platinum crucible, melted with a flux mixture of potassium carbonate, sodium carbonate and boric acid, and then dissolved by adding hydrochloric acid. A solution was prepared. In the Zr analysis, 0.2 g of the powder was weighed into a platinum crucible, heated and dried on a hot plate at 100°C using hydrofluoric acid and sulfuric acid, and treated with white smoke on a hot plate at 220°C. A measurement solution was prepared by adding water and nitric acid and heating and dissolving. In the analysis of U, 0.5 g of powder was weighed in a platinum crucible, heated and dried on a hot plate at 125 ° C. using hydrofluoric acid and nitric acid, potassium pyrosulfate was added to the residue, and dissolved with nitric acid. A measurement solution was prepared.

(crystal phase)
Identification of the crystal phase contained in the powder after crystallization and quantification of the content were performed by powder X-ray diffraction measurement/Rietveld method. The apparatus used was a sample horizontal multipurpose X-ray diffractometer (manufactured by Rigaku, Ultima IV), the X-ray source was CuKα, the tube voltage was 40 kV, the tube current was 40 mA, the scan speed was 10°/min, and the 2θ scan range was 10°~. Measured under the condition of 80°. Rietveld method software (manufactured by MDI, integrated powder X-ray software Jade+9) was used for quantitative analysis of the crystalline phase. The content b (mass%) of the β-quartz solid solution phase is crystallized so that α-alumina (internal standard substance), which is a standard material for X-ray diffraction manufactured by NIST, is 50% by mass (based on the total amount of the sample after addition). A sample added to the calcined powder was subjected to X-ray diffraction measurement, and the ratio a (% by mass) of the β-quartz solid solution obtained by Rietveld analysis was used to calculate the ratio a (% by mass) according to the following formula (2). The crystal structure of the β-quartz solid solution of the obtained powder was Zn _x /2Al _x Si _3-x O ₆ (x = 1) for Rietveld analysis. Quantitative analysis of the crystal layer was performed for all examples and comparative examples, and the results are shown in Table 1.
b=100a/(100-a) (2)

(average circularity)
After fixing the powder on the sample stage with carbon tape, osmium coating is applied, and an image with a resolution of 1280 x 1024 pixels and a magnification of 500 to 50000 times taken with a scanning electron microscope (JSM-7001F SHL, manufactured by JEOL Ltd.) is transferred to a personal computer. taken in. Using this image, an image analyzer (Nippon Roper Co., Ltd., Image-Pro Premier Ver.9.3) is used to calculate the projected area (S) of the particles (powder particles) and the projected perimeter (L) of the particles. Then, the degree of circularity was calculated from the following formula (1). Circularity was calculated for 100 arbitrary particles, and the average value was taken as the average circularity.
Circularity = 4πS/L ² (1)

(Average particle size)
The average particle size was measured using a laser diffraction particle size distribution analyzer (LS 13 320, manufactured by Beckman Coulter). 50 cm ³ of pure powder and 0.1 g of the obtained powder were placed in a glass beaker and dispersed for 1 minute with an ultrasonic homogenizer (SFX250, manufactured by BRANSON). A liquid dispersion of the powder subjected to dispersion treatment was added drop by drop using a dropper to a laser diffraction particle size distribution analyzer, and measurement was performed 30 seconds after adding a predetermined amount. The particle size distribution was calculated from the light intensity distribution data of the light diffracted/scattered by the particles detected by the sensor in the laser diffraction particle size distribution analyzer. The average particle size was obtained by multiplying the value of the measured particle size by the relative particle amount (difference %) and dividing by the total relative particle amount (100%). In addition, % here is volume %.

(X-ray transmission image evaluation)
The brightness of the observation image was evaluated using an X-ray transmission observation device. Bisphenol A type epoxy resin (manufactured by Mitsubishi Chemical Co., Ltd., jER828, 20 parts by mass) and a latent curing agent (manufactured by Tokyo Kasei Co., Ltd., 4,4'-diaminodiphenylmethane, 5 parts by mass) are mixed at 80 ° C. to form a resin mixture. was made. Next, the volume of this resin mixture is 70% by volume, and 30% by volume of powder is added, and stirred using a rotation/revolution mixer Awatori Mixer vacuum type (ARV-310P, manufactured by Thinky Co.) to obtain a powder resin composition. got stuff A predetermined volume of the obtained powdered resin composition was weighed, placed in a rectangular silicon frame with a thickness of 2 mm and a piece of 2 cm, and heated with a heat press ("IMC-1674-A" manufactured by Imoto Seisakusho Co., Ltd.). Pressure (80 ° C., 3 MPa, 1 hour) is performed, and a second heating and pressurizing (150 ° C., 5 MPa, 1 hour) is performed, and a third heating and pressurization (200 ° C., 7 MPa, 3 time) was performed and used as an evaluation sample. The shape and size can be mounted on the observation device, and there is no difference between the samples to be measured. For X-ray transmission observation, the evaluation sample was placed in the apparatus and observed. Based on the degree of brightness and darkness of the color of the observed image obtained, the image was evaluated as ◯ when the image had high lightness, and as x when the image had low lightness.

As can be seen from the results in Table 1, by limiting the amount of Zr in the powder, the brightness of the image in X-ray transmission observation can be increased. From this, it can be said that it is possible to suppress abnormality detection at the time of product analysis.

Claims (6)

_A powder comprising ZnO, _Al2O3 and _SiO2 ,
A powder, wherein the Zr content in the powder is 10 ppm or less with respect to the total amount of the powder. In the powder of claim 1,
A powder, wherein the U content in the powder is 10 ppb or less relative to the total amount of the powder. In the powder according to claim 1 or claim 2,
A powder having an average circularity of 0.6 or more. In the powder according to any one of claims 1 to 3,
A powder that is used by blending in glass or resin. A method for producing the powder according to any one of claims 1 to 4,
preparing _a raw material mixture comprising ZnO, _Al2O3 and _SiO2 ;
melting the raw material mixture;
cooling the melted raw material mixture to obtain raw glass;
and pulverizing the raw glass. In the method for producing a powder according to claim 5,
A method, wherein the raw material glass is pulverized in a stamp mill.