JP7406444B2 - Method for producing spherical particle material - Google Patents
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- 239000000463 material Substances 0.000 title claims description 73
- 239000012798 spherical particle Substances 0.000 title claims description 37
- 238000004519 manufacturing process Methods 0.000 title claims description 14
- 239000002245 particle Substances 0.000 claims description 102
- 239000002994 raw material Substances 0.000 claims description 56
- 238000005554 pickling Methods 0.000 claims description 38
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 29
- 229910052776 Thorium Inorganic materials 0.000 claims description 26
- 229910052770 Uranium Inorganic materials 0.000 claims description 26
- 239000002253 acid Substances 0.000 claims description 24
- 238000002844 melting Methods 0.000 claims description 15
- 230000008018 melting Effects 0.000 claims description 15
- 239000000155 melt Substances 0.000 claims description 9
- 238000000034 method Methods 0.000 description 43
- 239000007789 gas Substances 0.000 description 20
- 239000012535 impurity Substances 0.000 description 10
- 239000000243 solution Substances 0.000 description 9
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 8
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 7
- 238000010438 heat treatment Methods 0.000 description 7
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 6
- 238000005406 washing Methods 0.000 description 6
- 239000000945 filler Substances 0.000 description 5
- 238000007654 immersion Methods 0.000 description 5
- 239000000843 powder Substances 0.000 description 5
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 230000005260 alpha ray Effects 0.000 description 4
- 238000002485 combustion reaction Methods 0.000 description 4
- 239000002612 dispersion medium Substances 0.000 description 4
- 239000001294 propane Substances 0.000 description 4
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 229910001882 dioxygen Inorganic materials 0.000 description 3
- 238000010298 pulverizing process Methods 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- 238000004381 surface treatment Methods 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- 150000007513 acids Chemical class 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- FFUAGWLWBBFQJT-UHFFFAOYSA-N hexamethyldisilazane Chemical compound C[Si](C)(C)N[Si](C)(C)C FFUAGWLWBBFQJT-UHFFFAOYSA-N 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910017604 nitric acid Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000011236 particulate material Substances 0.000 description 2
- 229910000077 silane Inorganic materials 0.000 description 2
- -1 silane compound Chemical class 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- WBHQBSYUUJJSRZ-UHFFFAOYSA-M sodium bisulfate Chemical compound [Na+].OS([O-])(=O)=O WBHQBSYUUJJSRZ-UHFFFAOYSA-M 0.000 description 2
- 229910000342 sodium bisulfate Inorganic materials 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 238000004131 Bayer process Methods 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 239000003929 acidic solution Substances 0.000 description 1
- 239000003570 air Substances 0.000 description 1
- 125000000217 alkyl group Chemical group 0.000 description 1
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 125000003277 amino group Chemical group 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 125000002490 anilino group Chemical group [H]N(*)C1=C([H])C([H])=C([H])C([H])=C1[H] 0.000 description 1
- 239000011260 aqueous acid Substances 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
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- 239000012530 fluid Substances 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- 238000001095 inductively coupled plasma mass spectrometry Methods 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 239000011147 inorganic material Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000010309 melting process Methods 0.000 description 1
- 125000005641 methacryl group Chemical group 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 description 1
- 230000002285 radioactive effect Effects 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 150000004756 silanes Chemical class 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 238000005563 spheronization Methods 0.000 description 1
- 239000002918 waste heat Substances 0.000 description 1
Landscapes
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Description
本発明は、アルミナを主成分とする球状粒子材料の製造方法に関する。 The present invention relates to a method for producing a spherical particle material containing alumina as a main component.
現在、電子機器の小型化、高密度化、高出力化が進んでいる。そのような電子機器は熱の放出量が多くなり、電子機器の性能維持乃至性能向上のためには適切な熱対策を行って適正に冷却を行う必要がある。特に電子機器からの主な熱の発生源である半導体は樹脂中にフィラー材料を分散させた封止材により封止されており、特にフィラー材料の熱伝導性を向上することが求められている。 Currently, electronic devices are becoming smaller, more densely packed, and more powerful. Such electronic devices emit a large amount of heat, and in order to maintain or improve the performance of the electronic devices, it is necessary to take appropriate heat countermeasures and cool them appropriately. In particular, semiconductors, which are the main source of heat from electronic devices, are encapsulated with an encapsulant in which filler material is dispersed in resin, and there is a particular need to improve the thermal conductivity of the filler material. .
従来、熱伝導性に優れたフィラー材料としてはアルミナを採用することがある。フィラー材料に求められる性能として放射性元素の含有量を低減して放出するα線量が低いことがある。例えば、ＵやＴｈの含有量を減らすことが行われている。例えば、ＵやＴｈの含有量は、それらの総量として５ｐｐｂ以下、及び／又は、α線量として０．０００２（ｃ／ｃｍ２・ｈ）以下であることが好ましい。 Conventionally, alumina has been used as a filler material with excellent thermal conductivity. As a performance required of filler materials, the content of radioactive elements may be reduced to emit a low amount of alpha rays. For example, efforts are being made to reduce the content of U and Th. For example, the content of U and Th is preferably 5 ppb or less as a total amount thereof, and/or 0.0002 (c/cm 2 ·h) or less as an α-ray dose.
例えばα線量が少ないアルミナを製造する方法としては、水酸化アルミニウムを酸洗してＵやＴｈなどの不純物を除去した後に加熱溶融させることでか焼させてアルミナに変換する方法が提案されている（特許文献１、２）。 For example, as a method for producing alumina with a low amount of α-rays, a method has been proposed in which aluminum hydroxide is pickled to remove impurities such as U and Th, and then heated and melted to calcinate and convert it into alumina. (Patent Documents 1 and 2).
本発明は上記実情に鑑み完成したものであり、水酸化アルミニウムを酸洗浄してα線量を低減させる以外の方法によりα線量を低減できるアルミナを主成分とする球状粒子材料の製造方法を提供することを解決すべき課題とする。 The present invention was completed in view of the above circumstances, and provides a method for producing a spherical particle material containing alumina as the main component, which can reduce the amount of alpha rays by a method other than washing aluminum hydroxide with acid to reduce the amount of alpha rays. This is a problem to be solved.
上記課題を解決する目的で本発明者らが鋭意検討を行った結果、アルミナを主成分とする粗原料粒子に対して酸洗浄を行った後に溶融・球状化を行った。その後に再度酸による洗浄を行うことによりＵやＴｈを効果的に除去することができることを発見して以下の発明を完成させた。 As a result of intensive studies by the present inventors for the purpose of solving the above problems, the coarse raw material particles containing alumina as a main component were washed with acid and then melted and spheroidized. They discovered that U and Th could be effectively removed by washing with acid again after that, and completed the following invention.
（１）すなわち、本発明の球状粒子材料の製造方法は、アルミナを主成分とする粗原料粒子材料を酸溶液中に浸漬して原料粒子材料にする第１酸洗工程と、
前記原料粒子材料を溶融して急冷することで球状化した粗球状粒子材料にする溶融球状化工程と、
前記粗球状粒子材料を酸溶液中に浸漬して球状粒子材料にする第２酸洗工程と、
を有する。
(1) That is, the method for producing a spherical particle material of the present invention includes a first pickling step in which a coarse raw material particle material containing alumina as a main component is immersed in an acid solution to form a raw material particle material;
A melting and spheroidizing step in which the raw material particle material is melted and rapidly cooled to form a spheroidized coarse spherical particle material;
a second pickling step of immersing the coarse spherical particle material in an acid solution to form a spherical particle material;
has.
すなわち、原料粒子材料は第１酸洗工程において、粗原料粒子材料を酸溶液中に浸漬されることにより、主としてその表面に存在するＵやＴｈが除去されたものである。ついで溶融球状化工程で、いったん原料粒子材料が溶融液状化し再び固体化するときに、原料粒子材料内部の結晶粒界に偏在していたために第１酸洗工程で除去しきれなかったＵやＴｈが粒子表面に移行すると考えられる。したがって、加熱溶融する前後で酸洗浄を行うことにより、効果的にＵやＴｈを低減できるため、α線量のより一層の低減が実現できる。 That is, the raw material particle material is obtained by immersing the coarse raw material particle material in an acid solution in the first pickling step, thereby mainly removing U and Th present on the surface thereof. Next, in the melt spheroidization step, when the raw material particles are once melted and liquefied and then solidified again, U and Th that were unevenly distributed in the grain boundaries inside the raw material particles and could not be removed in the first pickling step are removed. is thought to migrate to the particle surface. Therefore, by performing acid cleaning before and after heating and melting, U and Th can be effectively reduced, thereby realizing a further reduction in the α-ray dose.
上記（１）に記載の発明は、以下の（２）～（４）のうちの１つ以上を組み合わせることができる。
（２）前記第１酸洗工程及び前記第２酸洗工程のうちの少なくとも一方は高温環境下で行われる。高温環境を採用することにより酸洗によるα線量低下の効果を更に高くすることができる。
（３）前記溶融球状化工程の後に前記粗球状粒子材料から粒径が小さい材料を除去する分級工程を有する。アルミナを主成分とする粒子は、溶融後に固化する際に粒径が小さい粒子に不純物が集中することを発見した。そこで粒径が小さい材料を除去する分級工程を採用することでα線量を更に低減することが可能になった。
（４）前記第２酸洗工程後における前記球状粒子材料のＵ及びＴｈの総量が５ｐｐｂ以下である。
The invention described in (1) above can combine one or more of the following (2) to (4).
(2) At least one of the first pickling step and the second pickling step is performed in a high temperature environment. By employing a high-temperature environment, the effect of reducing alpha rays due to pickling can be further enhanced.
(3) After the melting and spheroidizing step, there is a classification step of removing materials with small particle sizes from the coarse spherical particle material. It was discovered that when particles whose main component is alumina are solidified after melting, impurities are concentrated in particles with a small particle size. Therefore, by adopting a classification process that removes materials with small particle sizes, it has become possible to further reduce the alpha-ray dose.
(4) The total amount of U and Th in the spherical particle material after the second pickling step is 5 ppb or less.
本発明の球状粒子材料の製造方法は、加熱溶融の前後で酸洗浄を行うことにより従来よりも簡単にα線量の低減を実現することが可能になった。 The method for producing a spherical particle material of the present invention makes it possible to reduce the α-ray dose more easily than before by performing acid washing before and after heating and melting.
本発明の球状粒子材料の製造方法について実施形態に基づき以下詳細に説明を行う。本実施形態の製造にて製造される球状粒子材料は、アルミナを主成分とする。特に本実施形態の製造方法にて製造される球状粒子材料はＵ及びＴｈの総量が５ｐｐｂ以下であることが好ましい。 The method for producing a spherical particle material of the present invention will be described in detail below based on embodiments. The spherical particle material manufactured in this embodiment has alumina as a main component. In particular, it is preferable that the total amount of U and Th in the spherical particle material manufactured by the manufacturing method of this embodiment is 5 ppb or less.
本明細書において「アルミナを主成分とする」とは、全体の質量を基準としてアルミナを５０％以上含有することを意味し、特に６０％以上、７０％以上、８０％以上、９０％以上、９５％以上、９９％以上であることが好ましい。特に不可避不純物以外は全てアルミナであることにすることも可能である。アルミナ以外に含有することができる材料としては水酸化アルミニウム、金属アルミニウム、金属ケイ素、シリカなどの無機材料である。水酸化アルミニウムは加熱溶融によりアルミナに変換され、金属アルミニウムは燃焼によりアルミナに変換される。金属ケイ素は燃焼によりシリカに変換される。 In this specification, "containing alumina as a main component" means containing 50% or more of alumina based on the total mass, particularly 60% or more, 70% or more, 80% or more, 90% or more, It is preferably 95% or more, and preferably 99% or more. In particular, it is also possible to use alumina for everything other than unavoidable impurities. Materials that can be contained other than alumina include inorganic materials such as aluminum hydroxide, metal aluminum, metal silicon, and silica. Aluminum hydroxide is converted to alumina by heating and melting, and metallic aluminum is converted to alumina by combustion. Metallic silicon is converted to silica by combustion.
本実施形態の球状粒子材料の製造方法は、第１酸洗工程と溶融球状化工程と第２酸洗工程とその他必要に応じて選択される工程とを有する。第１酸洗工程及び第２酸洗工程はＵ及びＴｈの含有量の低減を目的とするが、ＭｇやＮａなどその他の不純物の低減にも優れた作用効果を生じることが期待できる。 The method for producing a spherical particle material according to the present embodiment includes a first pickling step, a melt spheroidizing step, a second pickling step, and other steps selected as necessary. Although the first pickling step and the second pickling step are aimed at reducing the contents of U and Th, they can be expected to produce excellent effects in reducing other impurities such as Mg and Na.
第１酸洗工程は、粗原料粒子材料を酸溶液中に浸漬して原料粒子材料にする工程である。粗原料粒子材料は、アルミナを主成分とする材料から形成される。粗原料粒子材料は、どのような形状であってもよいが、特に球状であることが好ましい。 The first pickling step is a step in which the coarse raw material particles are immersed in an acid solution to form raw material particles. The coarse raw material particle material is formed from a material whose main component is alumina. The coarse raw material particles may have any shape, but are particularly preferably spherical.
粗原料粒子材料の製造方法は特に限定しないが、例えば、焼成法、電融法、溶融球状法、ＶＭＣ法、粉砕による方法が挙げられる。焼成法は、バイヤー法で得られた水酸化アルミニウムを脱水焼成して粉末化する方法である。電融法はアルミナ鉱石や仮焼アルミナ等のアルミナ原料を電気炉で溶融したのち冷却して固体化し、その後粉砕して粉末化する方法である。溶融球状法は、アルミナ又は水酸化アルミニウムを主成分とする材料からなる粉粒体を火炎中に投入して加熱溶融させることで球状化した後に急冷することで球状の粗原料粒子材料を製造する方法である。アルミナは加熱溶融した後に急冷することでそのまま球状のアルミナとなり、水酸化アルミニウムは加熱溶融過程で脱水化してアルミナに変換され、その後に急冷することにより球状のアルミナとなる。ＶＭＣ法は、金属アルミニウムを燃焼させて変換したアルミナの気体を急冷して液状化をし、最終的に凝固粉末化したものを回収する方法である。粉砕による方法は、アルミナの塊を粉砕により粉体化する方法である。粉砕の原料となるアルミナは、特に限定されない。 The method for producing the coarse raw material particles is not particularly limited, and examples thereof include a sintering method, an electrofusion method, a molten spheroid method, a VMC method, and a pulverization method. The calcination method is a method in which aluminum hydroxide obtained by the Bayer process is dehydrated and sintered to form a powder. The electrofusion method is a method in which alumina raw materials such as alumina ore and calcined alumina are melted in an electric furnace, cooled to solidify, and then crushed to powder. The fused spheroidal method produces spherical coarse raw material particles by throwing powder or granules made of a material whose main component is alumina or aluminum hydroxide into a flame, heating and melting the material, turning it into a spheroid, and then rapidly cooling it. It's a method. Alumina becomes spherical alumina by being heated and melted and then rapidly cooled, and aluminum hydroxide is dehydrated and converted to alumina during the heating and melting process, and then rapidly cooled to become spherical alumina. The VMC method is a method in which alumina gas, which is converted by burning metallic aluminum, is rapidly cooled and liquefied, and the resulting solidified powder is recovered. The pulverization method is a method in which a lump of alumina is pulverized into powder. Alumina used as a raw material for pulverization is not particularly limited.
粗原料粒子材料の粒径は製造する球状粒子材料の粒径に応じて設定する。例えば、粗原料粒子材料が粒度分布を有しており、その体積平均粒径の１／１０００～１／３程度の小さい粒子が、全粒子の体積を基準として５％以上含まれる場合は、目的とする球状粒子材料の粒径よりも僅かに小さい程度の粒径とすることが好ましい。後述する溶融球状化工程で小さい粒子が溶融して、少なくともその一部は体積平均粒径あるいはそれに近い大きさの母粒子に吸収されることにより、体積平均粒径が僅かに大きくなる傾向にあるからである（その１）。また、そうではなく、粗原料粒子材料が粒度分布を有してはいるが、その体積平均粒径の１／１０００～１／３程度の小さい粒子が全粒子の体積を基準として５％未満しか含まれない場合は、目的とする球状粒子材料の粒径よりも僅かに大きい程度の粒径とすることが好ましい。前述の場合と異なり、体積平均粒径の粒子に吸収される小さい粒子がほとんど存在しないため、溶融球状化後に体積平均粒径が大きくならず、むしろ形状がますます真球に近づくために体積平均粒径が小さくなる傾向があるからである（その２）。具体的には、体積平均粒径２０μｍ程度の球状粒子材料を製造する場合であって、前者（その１）の粗原料材料のときには、粗原料粒子材料の体積平均粒径は、１０μｍ～１８μｍ程度にすることが好ましく、一方、後者（その２）の粗原料材料のときには、粗原料粒子材料の体積平均粒径は、２２μｍ～２５μｍ程度にすることが好ましい。 The particle size of the coarse raw material particle material is set according to the particle size of the spherical particle material to be produced. For example, if the coarse raw material particle material has a particle size distribution and contains 5% or more of small particles of about 1/1000 to 1/3 of the volume average particle size based on the volume of all particles, The particle size is preferably slightly smaller than the particle size of the spherical particle material. The volume average particle size tends to become slightly larger as small particles are melted in the melt spheroidization process described below and at least a portion of them are absorbed by the mother particles having a volume average particle size or a size close to it. Because (Part 1) In addition, although the coarse raw material particle material has a particle size distribution, small particles of about 1/1000 to 1/3 of the volume average particle size account for less than 5% of the total particle volume. If it is not included, it is preferable that the particle size is slightly larger than the particle size of the target spherical particle material. Unlike the previous case, the volume average particle size does not increase after melt spheroidization because there are almost no small particles absorbed by the particles with the volume average particle size, but rather the volume average particle size increases as the shape becomes closer to a true sphere. This is because the particle size tends to become smaller (Part 2). Specifically, when producing a spherical particle material with a volume average particle diameter of about 20 μm, in the case of the former (part 1) coarse raw material, the volume average particle diameter of the coarse raw material particle material is about 10 μm to 18 μm. On the other hand, in the case of the latter (part 2) coarse raw material, the volume average particle diameter of the coarse raw material particle material is preferably about 22 μm to 25 μm.
粗原料粒子材料は、シラン化合物による表面処理を行ったものでも良い。表面処理を行うことにより流動性が向上したり、凝集性が低下したりするため好ましい。シラン化合物としては、フェニル基、アルキル基、アミノ基、フェニルアミノ基、メタクリル基、エポキシ基などを有する化合物や、ヘキサメチルジシラザンなどが例示できる。シラン化合物は複数種類を混合して表面処理乃至は順次表面処理を行うことができる。 The coarse raw material particles may be surface-treated with a silane compound. Surface treatment is preferred because it improves fluidity and reduces cohesion. Examples of the silane compound include compounds having a phenyl group, an alkyl group, an amino group, a phenylamino group, a methacryl group, an epoxy group, and hexamethyldisilazane. A plurality of types of silane compounds can be mixed to perform surface treatment or sequential surface treatment.
第１酸洗工程は、酸性溶液により粗原料粒子材料を洗浄する工程である。例えば、酸溶液中に粗原料粒子材料を所定時間浸漬した後に溶媒にて洗浄することが挙げられる。酸溶液としては酸水溶液を、溶媒としては水を挙げることができる。酸としては、硫酸、硝酸、塩酸、フッ酸、硫酸水素ナトリウムなどが例示でき、特に硫酸が採用できる。複数の酸を組み合わせることもできる。 The first pickling step is a step of washing the coarse raw material particles with an acidic solution. For example, the coarse raw material particles may be immersed in an acid solution for a predetermined period of time and then washed with a solvent. Examples of the acid solution include an aqueous acid solution, and examples of the solvent include water. Examples of acids include sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid, and sodium hydrogen sulfate, with sulfuric acid being particularly suitable. It is also possible to combine multiple acids.
酸の濃度としては１．５質量％～１２．５質量％程度が例示できる。酸濃度の下限値としては、１．５質量％、３質量％、４．５質量％が例示でき、上限値としては、７．５質量％、９質量％、１２．５質量％が例示できる。これらの上限値と下限値とは任意に組み合わせることができる。これらの下限値以上にすることにより不純物を十分に溶解除去することが可能になり、これらの上限値以下にすることにより粗原料粒子材料への必要以上の酸の作用を抑制できる。 An example of the concentration of the acid is about 1.5% by mass to 12.5% by mass. Examples of the lower limit of the acid concentration are 1.5% by mass, 3% by mass, and 4.5% by mass, and the upper limits are exemplified by 7.5% by mass, 9% by mass, and 12.5% by mass. . These upper limit values and lower limit values can be arbitrarily combined. By setting the amount above these lower limits, impurities can be sufficiently dissolved and removed, and by setting the amount below these upper limits, it is possible to suppress the action of acid on the coarse raw material particles more than necessary.
酸洗浄の温度としては特に限定しないが温度が高い方が不純物の除去速度が速くなるため好ましい。例えば、常温（２５℃）以上、４０℃以上、６０℃以上、８０℃以上、１００℃以上が例示できる。溶媒の沸点以上の温度で酸洗浄を行う場合には加圧条件を採用することができる。 The temperature for acid washing is not particularly limited, but higher temperatures are preferable because the removal rate of impurities becomes faster. For example, the temperature may be at room temperature (25°C) or higher, 40°C or higher, 60°C or higher, 80°C or higher, or 100°C or higher. When acid washing is performed at a temperature higher than the boiling point of the solvent, pressurized conditions can be employed.
酸溶液に浸漬する条件としては特に限定されないが、２時間～１６時間程度浸漬を行うことができる。浸漬時間の下限値としては、２時間、３時間、４時間が例示でき、上限値としては、８時間、１２時間、１６時間が例示できる。これらの上限値と下限値とは任意に組み合わせることができる。これらの下限値以上の浸漬時間を採用することにより不純物が酸溶液中に十分に溶け出すことが可能になり、この上限値以下の時間を採用することにより不純物の溶出速度が低くなって不純物低減がそれ以上進行し難くなった場合の時間の無駄を省くことができる。 The conditions for immersion in the acid solution are not particularly limited, but immersion can be performed for about 2 hours to 16 hours. Examples of the lower limit of the immersion time are 2 hours, 3 hours, and 4 hours, and the upper limits are 8 hours, 12 hours, and 16 hours. These upper limit values and lower limit values can be arbitrarily combined. By adopting an immersion time that is longer than these lower limits, impurities can be sufficiently dissolved into the acid solution, and by adopting a time that is less than this upper limit, the elution rate of impurities is lowered, reducing impurities. It is possible to avoid wasting time when it becomes difficult to proceed further.
溶融球状化工程は、原料粒子材料を加熱溶融して球状化した後に急冷して粗球状粒子材料とする工程である。溶融球状化工程により原料粒子材料の形態によらず球形度が高い粗球状粒子材料が得られる。例えば粗球状粒子材料の球形度としては特に限定しないが、０．８以上、０．９以上、０．９５以上、０．９９以上とすることが例示できる。球形度は、ＳＥＭで写真を撮り、その観察される粒子の面積と周囲長から、（球形度）＝｛４π×（面積）÷（周囲長）２｝で算出される値として算出する。１に近づくほど真球に近い。具体的には画像処理装置（スペクトリス株式会社：ＦＰＩＡ－３０００）を用いて１００個の粒子について測定した平均値を採用する。 The melting and spheroidizing step is a step in which the raw material particles are heated and melted to become spheroidized, and then rapidly cooled to obtain coarse spherical particles. Through the melt spheroidization process, coarse spherical particle material with high sphericity can be obtained regardless of the form of the raw material particle material. For example, the sphericity of the coarse spherical particle material is not particularly limited, but examples include 0.8 or more, 0.9 or more, 0.95 or more, and 0.99 or more. Sphericity is calculated as a value calculated from the area and circumference of the observed particle by taking a photograph with an SEM, as follows: (sphericity)={4π×(area)÷(perimeter) 2 }. The closer it is to 1, the closer it is to a perfect sphere. Specifically, the average value measured for 100 particles using an image processing device (FPIA-3000, Spectris Corporation) is used.
加熱溶融の条件は特に限定しないが、高温雰囲気下に原料粒子材料同士を離間した状態で投入して行うことが好ましい。原料粒子材料は、適正な分散媒中に分散した状態で高温雰囲気下に投入される。分散媒としては、空気、窒素、アルゴン、酸素などの気体や、水、アルコールなどの液体が挙げられる。気体中に分散させる場合には原料粒子材料は乾燥した状態にすることができる。 Although the conditions for heating and melting are not particularly limited, it is preferable to conduct the heating and melting by charging the raw material particles in a state in which they are spaced apart from each other in a high-temperature atmosphere. The raw material particles are introduced into a high temperature atmosphere while being dispersed in an appropriate dispersion medium. Examples of the dispersion medium include gases such as air, nitrogen, argon, and oxygen, and liquids such as water and alcohol. When dispersed in a gas, the raw particle material can be in a dry state.
分散媒となる気体中に原料粒子材料を分散させる条件としては、気体中に原料粒子材料を１ｋｇ／Ｎｍ３～８ｋｇ／Ｎｍ３となるよう投入することにより分散されるようになる。原料粒子材料の分散量の下限値としては、２ｋｇ、３ｋｇが例示でき、上限値としては、６ｋｇ、７ｋｇが例示できる。これらの上限値と下限値とは任意に組み合わせることができる。原料粒子材料の分散量をこれらの下限値以上にすることにより気体中に原料材料粒子同士が十分離間した状態で加熱溶融できるため球形度が上がりやすくなり、これらの上限値以下にすることにより溶融球状化雰囲気の温度の低下を抑制できるし、気体の無駄な消費を抑えることができることとなる。 The conditions for dispersing the raw material particulate material in the gas serving as the dispersion medium are such that the raw material particulate material is introduced into the gas at a rate of 1 kg/Nm 3 to 8 kg/Nm 3 . Examples of the lower limit of the amount of dispersion of the raw material particle material include 2 kg and 3 kg, and the upper limit thereof include 6 kg and 7 kg. These upper limit values and lower limit values can be arbitrarily combined. By setting the amount of dispersion of the raw material particle material at or above these lower limits, it is possible to heat and melt the raw material particles in the gas with sufficient distance between them, making it easier to increase the sphericity. This makes it possible to suppress a decrease in the temperature of the spheroidizing atmosphere and to suppress wasteful consumption of gas.
また、溶融球状化の溶融火炎形成のための可燃性ガスは特に限定はしないが、プロパンガス、都市ガス、アセチレンガス、水素、アンモニア等が採用できる。単位量当たりの燃焼熱量が高く、運搬容易性の観点からプロパンガスが望ましい。たとえばプロパンガスを使用する場合、その単位時間あたりの投入量は特に限定しないが、１５Ｎｍ３／ｈ～４５Ｎｍ３／ｈ程度にすることができる。単位時間あたりの投入量の下限値としては、１５Ｎｍ３／ｈ、２０Ｎｍ３／ｈ、２５Ｎｍ３／ｈが例示でき、上限値としては、３５Ｎｍ３／ｈ、４０Ｎｍ３／ｈ、４５Ｎｍ３／ｈが例示できる。これらの上限値と下限値とは任意に組み合わせることができる。単位時間あたりの投入量をこれらの下限値以上にすることにより溶融球状化に十分な熱量を確保できるため球形度が上がりやすくなり、これらの上限値以下にすることにより導電性を有するカーボン成分の無用な生成を抑えることができるようになる。 The combustible gas for forming the molten flame for spheroidization is not particularly limited, but propane gas, city gas, acetylene gas, hydrogen, ammonia, etc. can be used. Propane gas is preferable from the viewpoint of high combustion heat per unit amount and ease of transportation. For example, when using propane gas, the amount of gas input per unit time is not particularly limited, but can be approximately 15 Nm 3 /h to 45 Nm 3 /h. Examples of the lower limit of the input amount per unit time are 15Nm 3 /h, 20Nm 3 /h, and 25Nm 3 /h, and the upper limit is 35Nm 3 /h, 40Nm 3 /h, and 45Nm 3 /h. I can give an example. These upper limit values and lower limit values can be arbitrarily combined. By setting the input amount per unit time at or above these lower limits, it is possible to secure sufficient heat for melting and spheroidizing, making it easier to increase the sphericity, and by setting the amount at or below these upper limits, it is possible to increase the sphericity of the conductive carbon component. It will be possible to suppress unnecessary generation.
なお、溶融球状化の溶融火炎形成のための助燃性ガスは酸素または空気とすればよく、可燃性ガスが燃焼するに足るよう、単位時間あたりの投入量を調整すればよい。 The auxiliary gas for forming the molten flame for spheroidization may be oxygen or air, and the input amount per unit time may be adjusted so as to combust the combustible gas.
原料粒子材料を供給する速度は特に限定しないが、１０ｋｇ／ｈ～１６０ｋｇ／ｈ程度にすることができる。原料粒子材料の供給速度の下限値としては、１０ｋｇ／ｈ、１５ｋｇ／ｈ、２０ｋｇ／ｈが例示でき、上限値としては、１４０ｋｇ／ｈ、１５０ｋｇ／ｈ、１６０ｋｇ／ｈが例示できる。これらの上限値と下限値とは任意に組み合わせることができる。原料粒子材料の供給速度をこれらの下限値以上にすることにより原料粒子材料の溶融球状化に使用されない無駄な廃熱を減らすことができ、これらの上限値以下にすることにより溶融球状化が不十分のため球形度の低いもの生成を抑制できる。 The speed at which the raw material particles are fed is not particularly limited, but can be approximately 10 kg/h to 160 kg/h. Examples of the lower limit value of the feed rate of the raw material particle material are 10 kg/h, 15 kg/h, and 20 kg/h, and the upper limit value is 140 kg/h, 150 kg/h, and 160 kg/h. These upper limit values and lower limit values can be arbitrarily combined. By setting the supply rate of the raw material particles at or above these lower limits, it is possible to reduce wasted waste heat that is not used for melting and spheroidizing the raw material particles, and by setting the supply rate at or below these upper limits, it is possible to prevent melting and spheroidization. Since the sphericity is sufficient, the formation of particles with low sphericity can be suppressed.
第２酸洗工程は、粗球状粒子材料を酸洗する工程である。酸洗の方法、条件としては第１酸洗工程と同様の条件を採用することができる。なお、第１酸洗工程及び第２酸洗工程の何れかは高温雰囲気下にて行うことが望ましい。高温環境とは、常温より高い環境である。特に５０℃以上、７０℃以上、１００℃以上、１２０℃以上などの環境が好ましい環境として採用できる。なお、沸点以上の温度にする場合には高圧環境を採用する。例えば１２１℃、２気圧である。 The second pickling step is a step of pickling the coarse spherical particle material. As the pickling method and conditions, the same conditions as in the first pickling step can be adopted. Note that either the first pickling step or the second pickling step is preferably performed in a high-temperature atmosphere. A high temperature environment is an environment higher than normal temperature. In particular, an environment of 50° C. or higher, 70° C. or higher, 100° C. or higher, or 120° C. or higher can be adopted as a preferable environment. Note that a high-pressure environment is used when the temperature is higher than the boiling point. For example, the temperature is 121°C and 2 atmospheres.
その他の工程としては、分級工程を行うことができる。分級工程は、溶融球状化工程にて製造した粗原料粒子材料から粒径が小さい粒子を除去する工程である。粗球状粒子材料を加熱溶融する際に含有するＵやＴｈが蒸発する。その後急冷により粗球状粒子材料になるが、蒸発したＵやＴｈは、粒径が大きい粒子よりも粒径が相対的に小さい粒子の方に取り込まれやすい傾向がある。そのため、粒径が相対的に小さい材料を除去することにより不純物の量を低減できる。 As other steps, a classification step can be performed. The classification process is a process of removing particles with small particle sizes from the coarse raw material particles produced in the melt spheroidization process. When the coarse spherical particle material is heated and melted, the U and Th contained therein evaporate. After that, it becomes a coarse spherical particle material by rapid cooling, but the evaporated U and Th tend to be more easily incorporated into particles with a relatively small particle size than particles with a large particle size. Therefore, the amount of impurities can be reduced by removing materials with relatively small particle sizes.
分級の方法は限定しないが、篩を通過させる方法、遠心力を用いる方法、流体中での沈降速度の差を用いる方法などの通常の分級操作が採用できる。特に、分級操作としてサイクロン分級などの遠心分級を採用した場合には蒸発したＵやＴｈは分級時に気流に乗って小粒径の粒子と共に分離されることになり、その結果、蒸発したＵやＴｈは共存する小粒径の粒子に取り込まれる傾向が高くなる。 The classification method is not limited, but usual classification operations such as passing through a sieve, using centrifugal force, and using a difference in sedimentation speed in a fluid can be employed. In particular, when centrifugal classification such as cyclone classification is adopted as the classification operation, evaporated U and Th will be separated along with small-sized particles in the airflow during classification, and as a result, evaporated U and Th has a high tendency to be incorporated into coexisting small-sized particles.
・第１酸洗工程
原料（大平洋ランダム株式会社製電融法アルミナ、ＬＡ１２００(体積平均粒径１４μｍ、比表面積２．６ｍ２／ｇ、ＬＡ２０００（体積平均粒径７μｍ、比表面積３．８ｍ２／ｇ）、ＬＡ４０００（体積平均粒径３μｍ、比表面積８．４ｍ２／ｇ））に対し、様々な酸の種類及び水溶液濃度で、温度、圧力（２５℃１ａｔｍまたは１２１℃２ａｔｍ）、時間（２、４、８、１６ｈ）を様々に組み合わせて浸漬処理を行った。そして、原料および第１酸洗工程後のものについてＵ、Ｔｈの含有量をＡｇｉｌｅｎｔ Ｔｅｃｈｎｏｌｏｇｉｅｓ社製ＩＣＰ－ＭＳで測定した。結果を表１に示す。
・First pickling process Raw materials (electrofused alumina manufactured by Pacific Random Co., Ltd., LA1200 (volume average particle diameter 14 μm, specific surface area 2.6 m 2 /g, LA2000 (volume average particle diameter 7 μm, specific surface area 3.8 m 2 /g), LA4000 (volume average particle diameter 3 μm, specific surface area 8.4 m 2 /g)) at various acid types and aqueous solution concentrations, temperature, pressure (25°C 1 atm or 121°C 2 atm), time ( 2, 4, 8, and 16 h) in various combinations.Then, the contents of U and Th in the raw materials and those after the first pickling step were measured using ICP-MS manufactured by Agilent Technologies. The results are shown in Table 1.
第１酸洗工程を経ることによりＵの含有量が低減できることが分かった。特に、試験例１０、１１とそれ以外との比較により、硫酸、硝酸、硫酸水素ナトリウムはフッ酸と異なり、ＵのみならずＴｈの低減もすることができることが分かった。さらに、試験例２及び３、試験例４及び５、試験例２６及び２７、試験例３３及び３４の各比較から、同じ酸の種類及び水溶液濃度であっても高温で行うことにより、Ｕ及びＴｈの量を更に低減することが可能であることが分かった。また、試験例１７乃至２０や、試験例２８乃至３１の各比較から、浸漬時間が長いほうがＵ及びＴｈの量の低減できる傾向にあることが分かった。なお、同じ種類の原料でもＵ及びＴｈの含有量が異なるものがあるのはロット差と考えられる。 It was found that the U content could be reduced by going through the first pickling step. In particular, by comparing Test Examples 10 and 11 with others, it was found that sulfuric acid, nitric acid, and sodium hydrogen sulfate, unlike hydrofluoric acid, can reduce not only U but also Th. Furthermore, from the comparisons of Test Examples 2 and 3, Test Examples 4 and 5, Test Examples 26 and 27, and Test Examples 33 and 34, it was found that even with the same type of acid and aqueous solution concentration, by conducting at high temperature, U and Th It has been found that it is possible to further reduce the amount of . Further, from the comparisons of Test Examples 17 to 20 and Test Examples 28 to 31, it was found that the longer the immersion time, the more likely the amount of U and Th could be reduced. It should be noted that the fact that some raw materials of the same type have different U and Th contents is considered to be due to lot differences.
・溶融球状化工程
代表として試験例１、１６、２６、２７の原料粒子材料について、以下の溶融球状化工程に相当する工程を実施した。炉内に、溶融火炎形成用に可燃性ガスとしてのプロパンガス（３５Ｎｍ３／ｈ）及び、助燃性ガスとしての酸素ガス（８２Ｎｍ３／ｈ）の混合ガスを供給し火炎を生成しながら、更に酸素ガスを８２Ｎｍ３／ｈで炉内に供給した。
- Melting spheronization process As a representative example, the raw material particle materials of Test Examples 1, 16, 26, and 27 were subjected to a process corresponding to the following melt spheroidization process. A mixed gas of propane gas (35 Nm 3 /h) as a combustible gas and oxygen gas (82 Nm 3 /h) as a combustion auxiliary gas was supplied into the furnace to form a molten flame, and while generating a flame, Oxygen gas was supplied into the furnace at 82 Nm 3 /h.
原料粒子材料を２０ｋｇ／ｈとし、分散媒としての酸素ガス（１．５ｋｇ／Ｎｍ３）に分散させた混合物を炉内に生成した火炎中に供給した。 A mixture of raw material particles at a rate of 20 kg/h and dispersed in oxygen gas (1.5 kg/Nm 3 ) as a dispersion medium was supplied into the flame generated in the furnace.
火炎中で原料粒子材料が加熱溶融された後、重力により下方に移動することで溶融した原料粒子材料は急冷されて粗球状粒子材料となった。得られた粗球状粒子材料は、サイクロン分級機で、大粒子側の粗球状粒子材料（ＣＹ品）と、小粒子側の粗原料粒子材料とに分級した。小粒子側の粗原料粒子材料（ＢＧ品）はバグフィルタにより捕集した。 After the raw material particle material was heated and melted in the flame, the melted raw material particle material moved downward by gravity and was rapidly cooled to become coarse spherical particle material. The obtained coarse spherical particle material was classified into coarse spherical particle material (CY product) on the large particle side and coarse raw material particle material on the small particle side using a cyclone classifier. The coarse raw material particle material (BG product) on the small particle side was collected by a bag filter.
・第２酸洗工程
さらに、大粒子側の粗球状粒子材料に対して、第２酸洗工程として前述の第１酸洗工程と同じ工程を実施し、得られた各試験例の各工程前後でのＵ及びＴｈの量を測定した。結果を表２に示す。
・Second pickling process Furthermore, the same process as the above-mentioned first pickling process was carried out on the coarse spherical particle material on the large particle side as a second pickling process, and each test example was obtained before and after each process. The amounts of U and Th were measured. The results are shown in Table 2.
溶融球状化工程及び分級工程を経たＣＹ品について、原料粒子材料よりＵ及びＴｈの量が低減できることが分かった。その一方でＢＧ品のほうがＵ及びＴｈ量が増えていることから溶融球状化工程により、原料粒子材料に含有されているＵ及びＴｈが揮散して減少すると共に、サイクロン分級を行うことでＵ及びＴｈはＢＧ品の方に移行することが考えられた。 It was found that the amounts of U and Th can be reduced in the CY product that has undergone the melt spheroidization process and the classification process compared to the raw material particle material. On the other hand, since the BG product has higher amounts of U and Th, the U and Th contained in the raw material particles are volatilized and reduced during the melt spheroidization process, and the U and Th content is reduced by cyclone classification. It was thought that Th would shift toward the BG product.
更に、第２酸洗工程を行うことでＵ及びＴｈについて更なる除去が実現できることが分かった。溶融球状化工程により原料粒子材料内部に（特に結晶粒界に集中することが予測される）存在するＵ及びＴｈが粒子の表面に移行するために第２酸洗工程によりこれらが除去できることとなったと考えられた。 Furthermore, it was found that further removal of U and Th could be realized by performing the second pickling step. Due to the melt spheroidization process, U and Th present inside the raw material particles (especially expected to be concentrated at grain boundaries) migrate to the surface of the particles, so they can be removed by the second pickling process. It was thought that
試験例１、１６、２６、２７のサイクロン分級を行った試料（ＣＹ品）について第２酸洗工程後のもののＳＥＭ写真を図１～４に示す。どれも高い球形度を示し、フィラー用途に適したものであることが分かった。 SEM photographs of the cyclone-classified samples (CY products) of Test Examples 1, 16, 26, and 27 after the second pickling step are shown in FIGS. 1 to 4. All of them showed high sphericity and were found to be suitable for filler applications.
Claims (4)
前記原料粒子材料を溶融して急冷することで球状化した粗球状粒子材料にする溶融球状化工程と、
前記粗球状粒子材料を酸溶液中に浸漬して球状粒子材料にする第２酸洗工程と、
を有する球状粒子材料の製造方法。 A first pickling step in which a coarse raw material particle material containing alumina as a main component is immersed in an acid solution to obtain a raw material particle material;
A melting and spheroidizing step in which the raw material particle material is melted and rapidly cooled to form a spheroidized coarse spherical particle material;
a second pickling step of immersing the coarse spherical particle material in an acid solution to form a spherical particle material;
A method for producing a spherical particle material having the following.
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| JP2015145336A (en) | 2010-04-15 | 2015-08-13 | 新日鉄住金マテリアルズ株式会社 | spherical alumina powder |
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