JP2023106713A - Scaly boehmite aggregate and manufacturing method thereof - Google Patents
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- 229910001593 boehmite Inorganic materials 0.000 title claims abstract description 113
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 title claims abstract description 113
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 15
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 57
- 239000002245 particle Substances 0.000 claims abstract description 45
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 claims abstract description 24
- 238000003756 stirring Methods 0.000 claims abstract description 23
- 239000013078 crystal Substances 0.000 claims abstract description 21
- 239000000203 mixture Substances 0.000 claims abstract description 19
- 239000007900 aqueous suspension Substances 0.000 claims abstract description 17
- 235000021388 linseed oil Nutrition 0.000 claims abstract description 16
- 239000000944 linseed oil Substances 0.000 claims abstract description 16
- 238000000034 method Methods 0.000 claims abstract description 16
- 239000003822 epoxy resin Substances 0.000 claims abstract description 15
- 229920000647 polyepoxide Polymers 0.000 claims abstract description 15
- CDBYLPFSWZWCQE-UHFFFAOYSA-L sodium carbonate Substances [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims abstract description 14
- 238000010335 hydrothermal treatment Methods 0.000 claims abstract description 13
- 238000010521 absorption reaction Methods 0.000 claims abstract description 12
- 239000003921 oil Substances 0.000 claims abstract description 12
- 235000019198 oils Nutrition 0.000 claims abstract description 12
- 238000004898 kneading Methods 0.000 claims abstract description 11
- 238000007561 laser diffraction method Methods 0.000 claims abstract description 11
- 238000000790 scattering method Methods 0.000 claims abstract description 11
- 239000000654 additive Substances 0.000 claims abstract description 9
- 230000000996 additive effect Effects 0.000 claims abstract description 9
- 229910000029 sodium carbonate Inorganic materials 0.000 claims abstract description 7
- 239000001488 sodium phosphate Substances 0.000 claims abstract description 4
- 229910000162 sodium phosphate Inorganic materials 0.000 claims abstract description 4
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 claims abstract description 4
- 230000004580 weight loss Effects 0.000 claims description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 14
- 238000010438 heat treatment Methods 0.000 claims description 4
- 238000002411 thermogravimetry Methods 0.000 claims description 3
- 230000000052 comparative effect Effects 0.000 description 38
- 238000011049 filling Methods 0.000 description 13
- 239000011164 primary particle Substances 0.000 description 12
- 239000000463 material Substances 0.000 description 11
- 239000002994 raw material Substances 0.000 description 11
- 238000001878 scanning electron micrograph Methods 0.000 description 11
- 229910052751 metal Inorganic materials 0.000 description 10
- 239000011230 binding agent Substances 0.000 description 8
- 229920005989 resin Polymers 0.000 description 8
- 239000011347 resin Substances 0.000 description 8
- 239000008234 soft water Substances 0.000 description 8
- 239000007864 aqueous solution Substances 0.000 description 7
- 239000011342 resin composition Substances 0.000 description 7
- 238000006243 chemical reaction Methods 0.000 description 6
- 238000009826 distribution Methods 0.000 description 6
- 239000002002 slurry Substances 0.000 description 6
- 239000000047 product Substances 0.000 description 5
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 4
- 238000006297 dehydration reaction Methods 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- 230000007423 decrease Effects 0.000 description 3
- 239000003063 flame retardant Substances 0.000 description 3
- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- IISBACLAFKSPIT-UHFFFAOYSA-N bisphenol A Chemical compound C=1C=C(O)C=CC=1C(C)(C)C1=CC=C(O)C=C1 IISBACLAFKSPIT-UHFFFAOYSA-N 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 239000011231 conductive filler Substances 0.000 description 2
- 230000018044 dehydration Effects 0.000 description 2
- 239000000945 filler Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 239000007858 starting material Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- 239000013585 weight reducing agent Substances 0.000 description 2
- ULKLGIFJWFIQFF-UHFFFAOYSA-N 5K8XI641G3 Chemical compound CCC1=NC=C(C)N1 ULKLGIFJWFIQFF-UHFFFAOYSA-N 0.000 description 1
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 description 1
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 description 1
- 240000007594 Oryza sativa Species 0.000 description 1
- 235000007164 Oryza sativa Nutrition 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- ANBBXQWFNXMHLD-UHFFFAOYSA-N aluminum;sodium;oxygen(2-) Chemical compound [O-2].[O-2].[Na+].[Al+3] ANBBXQWFNXMHLD-UHFFFAOYSA-N 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910001424 calcium ion Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- RDYMFSUJUZBWLH-UHFFFAOYSA-N endosulfan Chemical compound C12COS(=O)OCC2C2(Cl)C(Cl)=C(Cl)C1(Cl)C2(Cl)Cl RDYMFSUJUZBWLH-UHFFFAOYSA-N 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000008103 glucose Substances 0.000 description 1
- 239000008233 hard water Substances 0.000 description 1
- 238000009775 high-speed stirring Methods 0.000 description 1
- 239000002932 luster Substances 0.000 description 1
- 229910001425 magnesium ion Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 150000004682 monohydrates Chemical class 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 239000011819 refractory material Substances 0.000 description 1
- 239000012779 reinforcing material Substances 0.000 description 1
- 235000009566 rice Nutrition 0.000 description 1
- 239000011163 secondary particle Substances 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 229910001388 sodium aluminate Inorganic materials 0.000 description 1
- GCLGEJMYGQKIIW-UHFFFAOYSA-H sodium hexametaphosphate Chemical compound [Na]OP1(=O)OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])O1 GCLGEJMYGQKIIW-UHFFFAOYSA-H 0.000 description 1
- 235000019982 sodium hexametaphosphate Nutrition 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 239000001577 tetrasodium phosphonato phosphate Substances 0.000 description 1
- 238000002076 thermal analysis method Methods 0.000 description 1
- 239000002562 thickening agent Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- ASTWEMOBIXQPPV-UHFFFAOYSA-K trisodium;phosphate;dodecahydrate Chemical compound O.O.O.O.O.O.O.O.O.O.O.O.[Na+].[Na+].[Na+].[O-]P([O-])([O-])=O ASTWEMOBIXQPPV-UHFFFAOYSA-K 0.000 description 1
- 239000011800 void material Substances 0.000 description 1
Abstract
Description
本発明は、鱗片状ベーマイトの結晶同士が凝集した密なカードハウス構造を有するマイクロサイズの鱗片状ベーマイト凝集体及びその製造方法に関する。 TECHNICAL FIELD The present invention relates to micro-sized scale-like boehmite aggregates having a dense card house structure in which crystals of scale-like boehmite are aggregated together, and a method for producing the same.
アルミナ一水和物（ＡｌＯＯＨ）のベーマイトは、汎用性が高く、充填剤として補強材、難燃剤、光輝材、耐火材、増粘剤などに利用され、また、触媒担体、電気伝導フィラー母材、耐火物、高純度アルミナ用の原料、易焼結性アルミナ用の原料、蛍光材料用の原料などに利用されている。ベーマイトは、形態を制御して製造することができるため、ベーマイトの結晶は立方体状、板状、六角板状、円盤状、針状、鱗片状など種々の形態がある。また、ベーマイトは、製造方法によってベーマイトの結晶の凝集体が得られることがあり、ベーマイトの凝集体はベーマイトの結晶が分散したベーマイト粒子と同様に種々の用途に利用することができる。 Alumina monohydrate (AlOOH) boehmite is highly versatile and is used as a filler for reinforcing materials, flame retardants, luster materials, fireproof materials, thickeners, etc. It is also used as a catalyst carrier and an electrically conductive filler base material. , refractories, raw materials for high-purity alumina, raw materials for easily sinterable alumina, and raw materials for fluorescent materials. Since boehmite can be produced by controlling its shape, boehmite crystals have various shapes such as cubic, plate-like, hexagonal plate-like, disk-like, needle-like, and scale-like. Boehmite crystal aggregates can be obtained depending on the production method, and the boehmite aggregates can be used for various purposes in the same manner as boehmite particles in which boehmite crystals are dispersed.
従来、ベーマイトの凝集体についての報告がある（非特許文献１）。すなわち、非特許文献１には、アルミン酸ナトリウム液（バイヤー液）に界面活性剤のグルコースが加えられた液を７０℃で６０分撹拌しながら（熟成）、１Ｍ硫酸を用いてｐＨを１１．９から９．５まで中和させることによりベーマイトの花様凝集体が得られることが開示されている。（Ａｂｓｔｒａｃｔ、第１６８頁右欄下段） Conventionally, there is a report on aggregates of boehmite (Non-Patent Document 1). That is, in Non-Patent Document 1, a sodium aluminate solution (Bayer's solution) and glucose as a surfactant were stirred at 70° C. for 60 minutes (aging), and the pH was adjusted to 11.0 using 1M sulfuric acid. It is disclosed that neutralization from 9 to 9.5 yields boehmite flower-like aggregates. (Abstract, page 168, right column, bottom row)
しかし、上記の非特許文献１に開示のベーマイトの花様凝集体は、大きさが約１００ｎｍ～２００ｎｍ（第１７０頁左欄）、比表面積が２９３．６～３３１．５ｍ２／ｇ、細孔径が３．５～３．９ｎｍ及び細孔容積が０．２５８～０．３０８ｍ３／ｇ（第１７１頁のＴａｂｌｅ２．）のナノサイズでかつ結晶性の低いベーマイトの凝集体である。そのため、ベーマイトの花様凝集体は、熱伝導率が低いという問題、吸湿性が高いという問題及び結晶性の高いベーマイトに比べ脱水温度が低く、難燃剤としての利用性に問題がある。また、非特許文献１には、ベーマイトの花様凝集体が密なカードハウス構造を有することについては記載も示唆もない。 However, the boehmite flower-like aggregates disclosed in Non-Patent Document 1 have a size of about 100 nm to 200 nm (left column on page 170), a specific surface area of 293.6 to 331.5 m 2 /g, and a pore size of 3.5 to 3.9 nm and a pore volume of 0.258 to 0.308 m 3 /g (Table 2 on page 171). Therefore, the flower-like aggregates of boehmite have problems of low thermal conductivity, high hygroscopicity, and a low dehydration temperature compared to boehmite with high crystallinity, resulting in a problem of usability as a flame retardant. In addition, Non-Patent Document 1 does not describe or suggest that boehmite flower-like aggregates have a dense card house structure.
本発明は、上記の事情に鑑みなされたもので、結晶性の高い鱗片状ベーマイトの結晶同士が凝集した密なカードハウス構造を有するマイクロサイズの鱗片状ベーマイト凝集体及びその製造方法を提供することを課題とする。 The present invention has been made in view of the above circumstances, and provides a micro-sized scale-like boehmite aggregate having a dense card house structure in which highly crystalline scale-like boehmite crystals aggregate together, and a method for producing the same. is the subject.
上記の課題を解決するために、本発明の発明者等は鋭意検討し、本発明に想到した。
すなわち、請求項１に記載の発明は、鱗片状ベーマイトの結晶同士が凝集した密なカードハウス構造を有する鱗片状ベーマイト凝集体であって、ＪＩＳ Ｋ５１０１－１３－１（２００４）の精製あまに油法に準じて測定した、精製あまに油の吸油量が１８０ｇ／１００ｇ以下であり、かつエポキシ樹脂に練込限界まで充填した場合の熱線法で測定した、エポキシ樹脂組成物の面上の熱伝導率が０．９４Ｗ／ｍ・Ｋ以上であることを特徴とする鱗片状ベーマイト凝集体に関する。
In order to solve the above-described problems, the inventors of the present invention have made intensive studies and arrived at the present invention.
That is, the invention according to claim 1 is a scale-like boehmite aggregate having a dense card house structure in which crystals of scale-like boehmite are aggregated with each other, and is purified linseed oil according to JIS K5101-13-1 (2004). Thermal conductivity on the surface of the epoxy resin composition measured by the hot wire method when the refined linseed oil has an oil absorption of 180 g / 100 g or less and the epoxy resin is filled to the kneading limit, measured according to the method. It relates to scale-like boehmite aggregates characterized by having a modulus of 0.94 W/m·K or more.
請求項２に記載の発明は、請求項１に記載の発明において、下記の式を用いて算出した変動係数ＣＶが４０％以下でもよい。
標準偏差ＳＤ＝（Ｄ８４－Ｄ１６）／２ （式１）
変動係数ＣＶ＝（標準偏差ＳＤ／Ｄ５０）×１００ （式２）
The invention according to claim 2 is the invention according to claim 1, wherein the coefficient of variation CV calculated using the following formula may be 40% or less.
Standard deviation SD = (D84-D16) / 2 (Formula 1)
Coefficient of variation CV = (standard deviation SD / D50) × 100 (Formula 2)
請求項３に記載の発明は、請求項１又は請求項２に記載の発明において、熱重量分析で１００℃における重量減少率を０ｗｔ％とし、３０℃／ｍｉｎの昇温速度で加熱した際に１ｗｔ％の重量減少が確認された温度である１％重量減少温度が４２０℃以上でもよい。 The invention according to claim 3 is the invention according to claim 1 or claim 2, in which the weight reduction rate at 100 ° C. is set to 0 wt% by thermogravimetric analysis, and when heated at a temperature increase rate of 30 ° C./min. The 1% weight loss temperature, which is the temperature at which 1 wt% weight loss is confirmed, may be 420° C. or higher.
請求項４に記載の発明は、レーザー回折・散乱法で測定した平均粒径（体積基準）が４～２０μｍの水酸化アルミニウムと、水酸化ナトリウム、水酸化ナトリウムと炭酸ナトリウムの混合物及び水酸化ナトリウムとリン酸ナトリウムの混合物のいずれか１種の添加剤と、を含む水懸濁液を撹拌しながら水熱処理することを特徴とする請求項１～請求項３のいずれか１項に記載の鱗片状ベーマイト凝集体の製造方法に関する。 In the invention according to claim 4, aluminum hydroxide having an average particle size (volume basis) of 4 to 20 μm measured by a laser diffraction/scattering method, sodium hydroxide, a mixture of sodium hydroxide and sodium carbonate, and sodium hydroxide and any one additive of a mixture of sodium phosphate, and the scale according to any one of claims 1 to 3, wherein the hydrothermal treatment is performed while stirring the aqueous suspension containing The present invention relates to a method for producing boehmite aggregates.
請求項５に記載の発明は、請求項４に記載の発明において、水酸化アルミニウムの水に対する濃度が１～２０ｗｔ％で、添加剤の水に対する濃度が０．０５～２．００ｍｏｌ／Ｌであり、水熱処理の定温が１５０～２５０℃でもよい。 The invention according to claim 5 is the invention according to claim 4, wherein the concentration of aluminum hydroxide in water is 1 to 20 wt%, and the concentration of the additive in water is 0.05 to 2.00 mol/L. , the constant temperature of the hydrothermal treatment may be 150 to 250°C.
本発明の鱗片状ベーマイト凝集体は、密なカードハウス構造を有するため、樹脂などの被充填物への充填性に優れ、被充填物に等方的な熱伝導率を付与でき、ひいては樹脂などの被充填物の特性を活かしやすく、また、樹脂などの被充填物の軽量化に資することができる。 Since the scale-like boehmite aggregates of the present invention have a dense card house structure, they are excellent in fillability into a filling material such as a resin, and can impart isotropic thermal conductivity to the filling material. It is easy to take advantage of the characteristics of the filling material, and it can contribute to weight reduction of the filling material such as resin.
本発明の鱗片状ベーマイト凝集体は、粒度のばらつきが少なく粒子サイズが揃っているため、粒子サイズのばらつきに起因する最終製品の特性のばらつきを抑えることができる。例えばフィラー用途の場合、樹脂などの被充填物における特性のばらつきを減らすことが可能となり、また、塗料用途の場合、塗工液中の特性のばらつきを減らすことが可能となり、さらに、セラミックスの原材料として用いる場合、粒子サイズの不揃いに起因した焼結不良による特性のばらつきを防ぐことが可能となる。 Since the scale-like boehmite aggregates of the present invention have a uniform particle size with little variation in particle size, it is possible to suppress variations in the properties of the final product due to variations in particle size. For example, in the case of filler applications, it is possible to reduce the variation in the properties of the material to be filled, such as resin, and in the case of coating applications, it is possible to reduce the variation in the properties of the coating liquid. , it is possible to prevent variations in properties due to poor sintering due to non-uniform particle sizes.
本発明の鱗片状ベーマイト凝集体の製造方法は、有機系バインダーを使用することなく、鱗片状ベーマイト凝集体を直接合成するため、凝集体に有機系バインダーが残存することがない。一般的な有機系バインダーは、耐候性が高くなく劣化することが課題としてあり、長期的に凝集体を維持できない可能性があるが、本発明により鱗片状ベーマイトから構成される耐候性の高い凝集体を製造できる。 The method for producing scaly boehmite aggregates of the present invention directly synthesizes scaly boehmite aggregates without using an organic binder, so that no organic binder remains in the aggregates. The problem with general organic binders is that they do not have high weather resistance and deteriorate, and they may not be able to maintain aggregates for a long period of time. Aggregates can be manufactured.
本発明の鱗片状ベーマイト凝集体は、鱗片状ベーマイトの結晶同士が凝集した密なカードハウス構造を有し、カードハウス構造の空隙の容積を反映する、ＪＩＳ Ｋ５１０１－１３－１（２００４）の精製あまに油法に準じて測定した、精製あまに油の吸油量は１８０ｇ／１００ｇ以下が好ましく、１７０ｇ／１００ｇ以下がより好ましい。精製あまに油の吸油量の下限は、好ましくは８０ｇ／１００ｇ、より好ましくは９０ｇ／１００ｇでもよい。 The scale-like boehmite aggregates of the present invention have a dense card house structure in which crystals of scale-like boehmite are aggregated together, and reflect the volume of voids in the card house structure. The oil absorption of the refined linseed oil measured according to the linseed oil method is preferably 180 g/100 g or less, more preferably 170 g/100 g or less. The lower limit of the oil absorption of refined linseed oil is preferably 80 g/100 g, more preferably 90 g/100 g.
本発明の鱗片状ベーマイト凝集体は、カードハウス構造が密な構成で空隙の容積が小さいが、上記の吸油量は鱗片状ベーマイトの結晶が分散した空隙が少ない鱗片状ベーマイト粒子と比べて高い。一方、本発明の鱗片状ベーマイト凝集体の吸油量は、鱗片状ベーマイトの結晶同士が凝集した嵩高いカードハウス構造を有する鱗片状ベーマイト凝集体に比べて低い。 The scaly boehmite aggregates of the present invention have a dense card house structure and a small void volume, but the oil absorption is higher than that of scaly boehmite particles in which scaly boehmite crystals are dispersed and which have few voids. On the other hand, the oil absorption of the scale-like boehmite aggregates of the present invention is lower than that of the scale-like boehmite aggregates having a bulky card house structure in which crystals of scale-like boehmite aggregate.
本発明の鱗片状ベーマイト凝集体は、エポキシ樹脂に練込限界まで充填した場合の熱線法で測定した、エポキシ樹脂組成物の面上の熱伝導率が０．９４Ｗ／ｍ・Ｋ以上が好ましく、０．９６Ｗ／ｍ・Ｋ以上がより好ましい。本発明の鱗片状ベーマイト凝集体は、密なカードハウス構造を有するので、被充填物に充填し易く、被充填物に高い熱伝導性を付与することができる。 The scale-like boehmite aggregates of the present invention preferably have a thermal conductivity on the surface of the epoxy resin composition of 0.94 W/m·K or more, as measured by the hot wire method when the epoxy resin is filled up to the kneading limit. 0.96 W/m·K or more is more preferable. Since the scale-like boehmite aggregates of the present invention have a dense card house structure, they can be easily filled into a filling material and can impart high thermal conductivity to the filling material.
本発明の鱗片状ベーマイト凝集体は、下記の式を用い算出した変動係数ＣＶは４０％以下が好ましく、３８％以下がより好ましい。
標準偏差ＳＤ＝（Ｄ８４－Ｄ１６）／２ （式１）
変動係数ＣＶ＝（標準偏差ＳＤ／Ｄ５０）×１００ （式２）
本発明の鱗片状ベーマイト凝集体は、粒度のばらつきが少ない、いわば“粒の揃った”粒子である。また、本発明の鱗片状ベーマイト凝集体は、ベーマイトの結晶が分散した鱗片状ベーマイト粒子に比べても粒度のばらつきが少ない。
The scale-like boehmite aggregates of the present invention preferably have a coefficient of variation CV of 40% or less, more preferably 38% or less, calculated using the following formula.
Standard deviation SD = (D84-D16) / 2 (Formula 1)
Coefficient of variation CV = (standard deviation SD / D50) × 100 (Formula 2)
The scale-like boehmite aggregates of the present invention are particles with little variation in particle size, so to speak, "uniform" particles. In addition, the scale-like boehmite aggregates of the present invention have less variation in particle size than scale-like boehmite particles in which boehmite crystals are dispersed.
本発明の鱗片状ベーマイト凝集体を構成する鱗片状ベーマイトは、比表面積が数ｍ２／ｇを呈し、結晶性の高いマイクロサイズのベーマイトである。 The scale-like boehmite constituting the scale-like boehmite aggregate of the present invention is micro-sized boehmite with a specific surface area of several m 2 /g and high crystallinity.
本発明の鱗片状ベーマイト凝集体の１％重量減少温度は、４２０℃以上が好ましい。ここに、１％重量減少温度とは、熱重量分析において、１００℃における重量減少率を０ｗｔ％とし、３０℃／ｍｉｎの昇温速度で加熱した際に１ｗｔ％の重量減少が確認された温度と定義される。
ベーマイトは、熱を加えていくと脱水反応を起こし、γ-アルミナへ結晶相が転移するが、ベーマイトを難燃剤として用いる場合は脱水反応の開始温度は高いほど好ましく、ベーマイトの粒子が微細であるとか、結晶性が低いと低下する傾向にあり、１％重量減少温度も低下する。ナノサイズのベーマイトは、１％重量減少温度が３００℃程度であり、脱水温度が低すぎるためベーマイトの主要な用途でもある難燃剤として成形加工に高温が必要なプラスチック材料などには利用できない。また、後記の本発明の鱗片状ベーマイト凝集体の製造方法は、ポリビニルアルコールなどの有機系のバインダーを用いて凝集体を形成させるものではなく、鱗片状ベーマイト凝集体を直接合成するものである。有機系のバインダーを用いると、熱分析時に、生成物に残存する有機系のバインダーが分解して重量減少するため、１％重量減少温度の低下を招く。
すなわち、本発明の鱗片状ベーマイト凝集体は、マイクロサイズで結晶性が高く、また、製造に有機系のバインダーを使用しないため、４２０℃以上の１％重量減少温度を担保できる。
The 1% weight loss temperature of the scale-like boehmite aggregates of the present invention is preferably 420° C. or higher. Here, the 1% weight loss temperature is the temperature at which a weight loss of 1 wt% is confirmed when the rate of weight loss at 100° C. is assumed to be 0 wt % and the temperature is heated at a rate of 30° C./min in thermogravimetric analysis. is defined as
Boehmite undergoes a dehydration reaction when heat is applied, and the crystal phase transitions to γ-alumina. When using boehmite as a flame retardant, the higher the temperature at which the dehydration reaction starts, the better, and the finer the particles of boehmite. Or, if the crystallinity is low, it tends to decrease, and the 1% weight loss temperature also decreases. Nano-sized boehmite has a 1% weight loss temperature of about 300°C and a dehydration temperature that is too low. In addition, the method for producing scale-like boehmite aggregates of the present invention, which will be described later, does not use an organic binder such as polyvinyl alcohol to form aggregates, but directly synthesizes scale-like boehmite aggregates. When an organic binder is used, the organic binder remaining in the product is decomposed and the weight is reduced during thermal analysis, resulting in a decrease in the 1% weight loss temperature.
That is, the scale-like boehmite aggregates of the present invention are micro-sized and highly crystalline, and do not use an organic binder for production, so that a 1% weight loss temperature of 420° C. or higher can be ensured.
本発明の鱗片状ベーマイト凝集体は、タップ密度が０．２２ｇ／ｃｍ３以上が好ましく、０．２４ｇ／ｃｍ３以上がより好ましい。本発明の鱗片状ベーマイト凝集体のタップ密度は、鱗片状ベーマイトの結晶が分散した鱗片状ベーマイト粒子のタップ密度より高いため、タップ密度の低い、鱗片状ベーマイトの結晶が分散した鱗片状ベーマイト粒子は飛散し易いのに対し、本発明の鱗片状ベーマイト凝集体は飛散し難く、ハンドリング牲に優れている。 The scale-like boehmite aggregates of the present invention preferably have a tap density of 0.22 g/cm 3 or more, more preferably 0.24 g/cm 3 or more. Since the tap density of the scaly boehmite aggregates of the present invention is higher than the tap density of the scaly boehmite particles in which the scaly boehmite crystals are dispersed, the scaly boehmite particles in which the scaly boehmite crystals are dispersed have a low tap density. While it is easy to scatter, the scale-like boehmite aggregates of the present invention are difficult to scatter and are excellent in handleability.
次いで、本発明の鱗片状ベーマイト凝集体の製造方法について説明する。
本発明の鱗片状ベーマイト凝集体は、原料の水酸化アルミニウムと添加剤と、を含む水懸濁液を撹拌しながら水熱処理することにより得ることができる。
Next, the method for producing scale-like boehmite aggregates of the present invention will be described.
The scale-like boehmite aggregates of the present invention can be obtained by hydrothermally treating an aqueous suspension containing aluminum hydroxide as a raw material and an additive while stirring.
原料の水酸化アルミニウムは、レーザー回折・散乱法で測定した平均粒径（体積基準）が４～２０μｍが好ましく、５～１５μｍがより好ましい。水酸化アルミニウムの平均粒径が４μｍを下回ると、鱗片状ベーマイトの結晶同士が凝集した嵩高いカードハウス構造を形成できないからである。また、２０μｍを上回ると、反応中に沈降が起こりやすく、反応生成物で配管が詰まるなど水熱処理装置の毀損を招くおそれがある。
また、水酸化アルミニウムの水に対する濃度は、１～２０ｗｔ％が好ましく、２～１７ｗｔ％がより好ましい。１ｗｔ％を下回ると、ベーマイトの生成量が少なく不経済であり、２０ｗｔ％を上回ると合成中に粘度が高くなり、撹拌不良が起きやすくなるためである。
Aluminum hydroxide as a raw material preferably has an average particle diameter (volume basis) of 4 to 20 μm, more preferably 5 to 15 μm, as measured by a laser diffraction/scattering method. This is because if the average particle size of aluminum hydroxide is less than 4 μm, a bulky card house structure in which scaly boehmite crystals aggregate together cannot be formed. On the other hand, if it exceeds 20 μm, sedimentation is likely to occur during the reaction, and the reaction product may clog the pipes, resulting in damage to the hydrothermal treatment apparatus.
Further, the concentration of aluminum hydroxide in water is preferably 1 to 20 wt%, more preferably 2 to 17 wt%. If the content is less than 1 wt%, the amount of boehmite produced is small, which is uneconomical.
また、原料の水酸化アルミニウムの粒度は、均一牲の高いことが好ましい。すなわち、水酸化アルミニウムの粒度分布の形状は、正規分布を示すか、正規分布に近い単峰性の分布を示すものが好ましい。水酸化アルミニウムの粒度の均一性が高いほど、密なカードハウス構造を有する鱗片状ベーマイト凝集体を確実に得られるからである。
さらに、原料の水酸化アルミニウムは、ＳＥＭ像より測長された一次粒子の平均値が２～８μｍであり、それが凝集した二次粒子であるものが好ましい。
一次粒子の平均値が２μｍより小さいと鱗片状ベーマイトの結晶同士が凝集したカードハウス構造を形成しづらく、８μｍより大きいとカードハウス構造の中心部が空洞となり、凝集体が脆くなるためである。
Moreover, it is preferable that the particle size of aluminum hydroxide as a raw material has high uniformity. That is, the shape of the particle size distribution of aluminum hydroxide preferably exhibits a normal distribution or a unimodal distribution close to the normal distribution. This is because the higher the uniformity of the particle size of the aluminum hydroxide, the more reliably the scaly boehmite aggregates having a dense card house structure can be obtained.
Further, the raw material aluminum hydroxide preferably has an average primary particle size of 2 to 8 μm as measured by an SEM image, and is agglomerated secondary particles.
If the average value of the primary particles is less than 2 μm, it is difficult to form a card house structure in which scaly boehmite crystals aggregate with each other.
添加剤は、水酸化ナトリウム、水酸化ナトリウムと炭酸ナトリウムの混合物及び水酸化ナトリウムとリン酸ナトリウムの混合物から選ばれるいずれか１種が好ましい。添加剤の水に対する濃度は、０．０５～２．００ｍｏｌ／Ｌが好ましく、０．１０～１．００ｍｏｌ／Ｌがより好ましい。０．０５ｍｏｌ／Ｌを下回ると鱗片状のベーマイトになりづらく、２．００ｍｏｌ／Ｌを上回るとｐＨが高くなることによって生成したベーマイトが溶解してしまい、回収できる量が少なくなるためである。 The additive is preferably any one selected from sodium hydroxide, a mixture of sodium hydroxide and sodium carbonate, and a mixture of sodium hydroxide and sodium phosphate. The concentration of the additive to water is preferably 0.05 to 2.00 mol/L, more preferably 0.10 to 1.00 mol/L. If the concentration is less than 0.05 mol/L, it is difficult to form boehmite in the form of scales.
懸濁液の調製に用いる水は、硬水でも軟水でもよいが、マグネシウムイオンやカルシウムイオンの影響が少ない軟水が好ましい。 The water used for preparing the suspension may be either hard water or soft water, but soft water that is less affected by magnesium ions and calcium ions is preferred.
水熱処理の定温は、１５０～２５０℃が好ましく、１６０～２３０℃がより好ましい。
１５０℃を下回ると、水酸化アルミニウムからベーマイトへの反応が進みづらいためであり、２５０℃を上回ると高圧に耐えうる高価な設備が必要になるためである。
反応時間は、３時間～２４時間の範囲が好ましい。３時間未満では、鱗片状ベーマイト凝集体が得られないことがある。また、２４時間を超えても特に格別な効果がなく、エネルギー面でも不経済である。
また、定温までの昇温速度は、１００℃／ｈｏｕｒ以下が好ましい。１００℃／ｈｏｕｒ以下でないと反応容器内の温度にばらつきが生じやすく、均一な反応が進みづらくなるためである。
水熱処理の圧力は、定温における自然発生圧力が好ましく、特に加圧は要しない。
The constant temperature of the hydrothermal treatment is preferably 150-250°C, more preferably 160-230°C.
This is because if the temperature is lower than 150°C, the reaction from aluminum hydroxide to boehmite does not easily proceed, and if it exceeds 250°C, expensive equipment that can withstand high pressure is required.
The reaction time is preferably in the range of 3 hours to 24 hours. If it is less than 3 hours, scaly boehmite aggregates may not be obtained. Moreover, even if it exceeds 24 hours, there is no particular effect, and it is uneconomical in terms of energy.
Moreover, the rate of temperature increase to a constant temperature is preferably 100° C./hour or less. This is because if the temperature is not 100° C./hour or less, the temperature in the reaction vessel tends to vary, making it difficult for a uniform reaction to proceed.
The pressure for the hydrothermal treatment is preferably a spontaneously generated pressure at a constant temperature, and no particular pressurization is required.
水熱処理における撹拌の羽根先端速度（周速）は、０．４～４．０ｍ／ｓｅｃが好ましく、０．５～３．０ｍ／ｓｅｃがより好ましい。０．４ｍ／ｓｅｃを下回ると原料の沈降が起こりやすく均一な反応が進みづらくなるためであり、４．０ｍ／ｓｅｃを上回ると高速撹拌が可能な高価なモータが必要になるためである。
羽根先端速度（周速）は、下記の式で求めることができる。
Ｖ ＝ π × Ｄ × Ｎ／６０ （式３）
（Ｖ：羽根先端速度（m/s）、π：円周率、Ｄ：羽根径（m）、Ｎ：回転数（rpm））
The blade tip speed (peripheral speed) for stirring in the hydrothermal treatment is preferably 0.4 to 4.0 m/sec, more preferably 0.5 to 3.0 m/sec. This is because if the velocity is less than 0.4 m/sec, the raw materials tend to settle and the reaction does not progress uniformly, and if it exceeds 4.0 m/sec, an expensive motor capable of high-speed stirring is required.
The blade tip speed (peripheral speed) can be obtained by the following formula.
V = π × D × N/60 (Formula 3)
(V: blade tip speed (m/s), π: circumference ratio, D: blade diameter (m), N: rotation speed (rpm))
次いで、本発明を実施例を挙げて説明するが、本発明は以下の実施例に限定されるものではない。 EXAMPLES Next, the present invention will be described with reference to examples, but the present invention is not limited to the following examples.
〔実施例１〕
軟水7000gに水酸化ナトリウム（関東電化工業（株）製）59gを添加して透明な水溶液になるまで撹拌混合し、そこに水酸化アルミニウム（グレード名：BF083、平均粒子径（レーザー回折・散乱法）：10μm、一次粒子の平均値（ＳＥＭ像より３０点測長）：6.5μｍ、日本軽金属（株）製）700gを入れてよく撹拌混合して水懸濁液を調製した。この水懸濁液を撹拌型オートクレーブ（容積：10L）へ入れ、200℃で12時間、1.65m/secで撹拌（羽根径：0.195 m、162 rpm）しながら水熱処理した。なお、室温（25℃）から186℃までは2時間で昇温し、186℃から200℃までは0.5時間で昇温した。水熱処理後のスラリーを脱水、水洗、乾燥し、試料を得た。
[Example 1]
Add 59 g of sodium hydroxide (manufactured by Kanto Denka Kogyo Co., Ltd.) to 7000 g of soft water and stir and mix until a clear aqueous solution is formed. ): 10 µm, average value of primary particles (measured at 30 points from SEM image): 6.5 µm, 700 g of Nippon Light Metal Co., Ltd.) was added and thoroughly stirred to prepare an aqueous suspension. This aqueous suspension was placed in a stirring autoclave (volume: 10 L) and hydrothermally treated at 200° C. for 12 hours while stirring at 1.65 m/sec (blade diameter: 0.195 m, 162 rpm). The temperature was raised from room temperature (25°C) to 186°C in 2 hours, and from 186°C to 200°C in 0.5 hours. After the hydrothermal treatment, the slurry was dehydrated, washed with water, and dried to obtain a sample.
〔実施例２〕
軟水3000gに水酸化ナトリウム（関東電化工業（株）製）25gを添加して透明な水溶液になるまで撹拌混合し、そこに水酸化アルミニウム（グレード名：BF083、平均粒子径（レーザー回折・散乱法）：10μm、一次粒子の平均値（ＳＥＭ像より３０点測長）：6.5μｍ、日本軽金属（株）製）300gを入れてよく撹拌混合して水懸濁液を調製した。この水懸濁液を撹拌型オートクレーブ（容積：5L）へ入れ、180 ℃で8時間、1.49 m/sec で撹拌（羽根径：0.142 m、200 rpm）しながら水熱処理した。なお、室温（25℃）から180℃までは2時間で昇温した。水熱処理後のスラリーを脱水、水洗、乾燥し、試料を得た。
[Example 2]
Add 25 g of sodium hydroxide (manufactured by Kanto Denka Kogyo Co., Ltd.) to 3000 g of soft water and stir and mix until a clear aqueous solution is formed. ): 10 µm, average value of primary particles (measured at 30 points from SEM image): 6.5 µm, 300 g of Nippon Light Metal Co., Ltd.) was added and thoroughly stirred to prepare an aqueous suspension. This aqueous suspension was placed in a stirring autoclave (volume: 5 L) and hydrothermally treated at 180° C. for 8 hours while stirring at 1.49 m/sec (blade diameter: 0.142 m, 200 rpm). The temperature was raised from room temperature (25°C) to 180°C in 2 hours. After the hydrothermal treatment, the slurry was dehydrated, washed with water, and dried to obtain a sample.
〔実施例３〕
軟水3000gに水酸化ナトリウム（関東電化工業（株）製）25gを添加して透明な水溶液になるまで撹拌混合し、そこに水酸化アルミニウム（グレード名：B103、平均粒子径（レーザー回折・散乱法）：7μm、一次粒子の平均値（ＳＥＭ像より３０点測長）：4μｍ、日本軽金属（株）製）300gを入れてよく撹拌混合して水懸濁液を調製した。この水懸濁液を撹拌型オートクレーブ（容積：5L）へ入れ、200℃で12時間、1.49 m/sec で撹拌（羽根径：0.142 m、200 rpm）しながら水熱処理した。なお、室温（25℃）から186℃までは2時間で昇温し、186℃から200℃までは0.5時間で昇温した。水熱処理後のスラリーを脱水、水洗、乾燥し、試料を得た。
[Example 3]
Add 25 g of sodium hydroxide (manufactured by Kanto Denka Kogyo Co., Ltd.) to 3000 g of soft water and stir and mix until a clear aqueous solution is formed. ): 7 μm, average value of primary particles (measured at 30 points from SEM image): 4 μm, 300 g of Nippon Light Metal Co., Ltd.) was added and thoroughly stirred to prepare an aqueous suspension. This aqueous suspension was placed in a stirring autoclave (volume: 5 L) and hydrothermally treated at 200° C. for 12 hours while stirring at 1.49 m/sec (blade diameter: 0.142 m, 200 rpm). The temperature was raised from room temperature (25°C) to 186°C in 2 hours, and from 186°C to 200°C in 0.5 hours. After the hydrothermal treatment, the slurry was dehydrated, washed with water, and dried to obtain a sample.
〔実施例４〕
軟水3000gに炭酸ナトリウム（（株）トクヤマ製）86gと水酸化ナトリウム（関東電化工業（株）製） 10gを添加して透明な水溶液になるまで撹拌混合し、そこに水酸化アルミニウム（グレード名：BF083、平均粒子径（レーザー回折・散乱法）：10μm、一次粒子の平均値（ＳＥＭ像より３０点測長）：6.5μｍ、日本軽金属（株）製）300gを入れてよく撹拌混合して水懸濁液を調製した。この水懸濁液を撹拌型オートクレーブ（容積：5L）へ入れ、180 ℃で8時間、1.49 m/sec で撹拌（羽根径：0.142 m、200 rpm）しながら水熱処理した。なお、室温（25℃）から180℃までは2時間で昇温した。水熱処理後のスラリーを脱水、水洗、乾燥し、試料を得た。
[Example 4]
86 g of sodium carbonate (manufactured by Tokuyama Corporation) and 10 g of sodium hydroxide (manufactured by Kanto Denka Kogyo Co., Ltd.) were added to 3,000 g of soft water, stirred and mixed until a clear aqueous solution was formed, and aluminum hydroxide (grade name: BF083, average particle size (laser diffraction/scattering method): 10 μm, average value of primary particles (measured at 30 points from SEM image): 6.5 μm, 300 g of Nippon Light Metal Co., Ltd.) is added, stirred well, and mixed with water. A suspension was prepared. This aqueous suspension was placed in a stirring autoclave (volume: 5 L) and hydrothermally treated at 180° C. for 8 hours while stirring at 1.49 m/sec (blade diameter: 0.142 m, 200 rpm). The temperature was raised from room temperature (25°C) to 180°C in 2 hours. After the hydrothermal treatment, the slurry was dehydrated, washed with water, and dried to obtain a sample.
〔実施例５〕
軟水7000gに水酸化ナトリウム（関東電化工業（株）製）88gとリン酸ナトリウム・１２水和物（関東化学（株）製）13gを添加して透明な水溶液になるまで撹拌混合し、そこに水酸化アルミニウム（グレード名：BF083、平均粒子径（レーザー回折・散乱法）：10μm、一次粒子の平均値（ＳＥＭ像より３０点測長）：6.5μｍ、日本軽金属（株）製）700gを入れてよく撹拌混合して水懸濁液を調製した。この水懸濁液を撹拌型オートクレーブ（容積：10L）へ入れ、205℃で12時間、1.65 m/sec で撹拌（羽根径：0.195 m、162 rpm）しながら水熱処理した。なお、室温（25℃）から186℃までは2時間で昇温し、186℃から205℃までは0.5時間で昇温した。熱処理後のスラリーを脱水、水洗、乾燥し、試料を得た。
[Example 5]
Add 88 g of sodium hydroxide (manufactured by Kanto Denka Kogyo Co., Ltd.) and 13 g of sodium phosphate dodecahydrate (manufactured by Kanto Kagaku Co., Ltd.) to 7000 g of soft water and stir and mix until a clear aqueous solution is formed. 700 g of aluminum hydroxide (grade name: BF083, average particle size (laser diffraction/scattering method): 10 μm, average value of primary particles (measured at 30 points from SEM image): 6.5 μm, manufactured by Nippon Light Metal Co., Ltd.) was added. An aqueous suspension was prepared by thoroughly stirring and mixing. This aqueous suspension was placed in a stirring autoclave (volume: 10 L) and hydrothermally treated at 205° C. for 12 hours while stirring at 1.65 m/sec (blade diameter: 0.195 m, 162 rpm). The temperature was raised from room temperature (25°C) to 186°C in 2 hours, and from 186°C to 205°C in 0.5 hours. After the heat treatment, the slurry was dehydrated, washed with water, and dried to obtain a sample.
〔比較例１〕
水酸化アルミニウム（グレード名：BF013、平均粒子径（レーザー回折・散乱法）：1μm、一次粒子の平均値（ＳＥＭ像より３０点測長）：1μｍ、日本軽金属（株）製）に変更した以外は、実施例１と同様の方法で試料を製造した。
[Comparative Example 1]
Aluminum hydroxide (grade name: BF013, average particle size (laser diffraction/scattering method): 1 μm, average value of primary particles (measured at 30 points from SEM image): 1 μm, manufactured by Nippon Light Metal Co., Ltd.) produced samples in the same manner as in Example 1.
〔比較例２〕
水酸化アルミニウム（グレード名：BF013、平均粒子径（レーザー回折・散乱法）：1μm、一次粒子の平均値（ＳＥＭ像より３０点測長）：1μｍ、日本軽金属（株）製）に変更した以外は、実施例４と同様の方法で試料を製造した。
[Comparative Example 2]
Aluminum hydroxide (grade name: BF013, average particle size (laser diffraction/scattering method): 1 μm, average value of primary particles (measured at 30 points from SEM image): 1 μm, manufactured by Nippon Light Metal Co., Ltd.) prepared samples in a manner similar to that of Example 4.
〔比較例３〕
水酸化アルミニウム（グレード名：BF013、平均粒子径（レーザー回折・散乱法）：1μm、一次粒子の平均値（ＳＥＭ像より３０点測長）：1μｍ、日本軽金属（株）製）に変更した以外は、実施例５と同様の方法で試料を製造した。
[Comparative Example 3]
Aluminum hydroxide (grade name: BF013, average particle size (laser diffraction/scattering method): 1 μm, average value of primary particles (measured at 30 points from SEM image): 1 μm, manufactured by Nippon Light Metal Co., Ltd.) prepared samples in the same manner as in Example 5.
〔比較例４〕
軟水3000gに炭酸ナトリウム（（株）トクヤマ製）86gを添加して透明な水溶液になるまで撹拌混合し、そこに水酸化アルミニウム（グレード名：BF083、平均粒子径（レーザー回折・散乱法）：10μm、一次粒子の平均値（ＳＥＭ像より３０点測長）：6.5μｍ、日本軽金属（株）製）300gを入れてよく撹拌混合して水懸濁液を調製した。この水懸濁液を撹拌型オートクレーブ（容積：5L）へ入れ、180℃で10時間、1.71 m/sec で撹拌（羽根径：0.142 m、回転数：230 rpm）しながら水熱処理した。なお、室温（25℃）から180℃までは2時間で昇温した。水熱処理後のスラリーを脱水、水洗、乾燥し、試料を得た。
[Comparative Example 4]
Add 86 g of sodium carbonate (manufactured by Tokuyama Co., Ltd.) to 3000 g of soft water and stir and mix until a clear aqueous solution is formed. Aluminum hydroxide (grade name: BF083, average particle size (laser diffraction/scattering method): 10 μm) , Average value of primary particles (measured at 30 points from SEM image): 6.5 μm, manufactured by Nippon Light Metal Co., Ltd.) 300 g was added and thoroughly stirred to prepare an aqueous suspension. This aqueous suspension was placed in a stirring autoclave (volume: 5 L) and hydrothermally treated at 180° C. for 10 hours while stirring at 1.71 m/sec (blade diameter: 0.142 m, rotation speed: 230 rpm). The temperature was raised from room temperature (25°C) to 180°C in 2 hours. After the hydrothermal treatment, the slurry was dehydrated, washed with water, and dried to obtain a sample.
〔比較例５〕
水酸化アルミニウム（グレード名：BF083、平均粒子径（レーザー回折・散乱法）：10μm、一次粒子の平均値（ＳＥＭ像より３０点測長）：6.5μｍ、日本軽金属（株）製）に変更し、また、水酸化ナトリウムと水酸化アルミニウムが混合された水懸濁液を撹拌混合することなく静置して水熱処理した以外は実施例３と同様な方法で試料を製造した。
[Comparative Example 5]
Aluminum hydroxide (grade name: BF083, average particle size (laser diffraction/scattering method): 10 μm, average value of primary particles (measured at 30 points from SEM image): 6.5 μm, manufactured by Nippon Light Metal Co., Ltd.) Also, a sample was prepared in the same manner as in Example 3, except that the water suspension in which sodium hydroxide and aluminum hydroxide were mixed was allowed to stand without being stirred and mixed, and was hydrothermally treated.
上記の実施例１～実施例５及び比較例１～比較例５について、下記の各種の試験を行った。 The following various tests were performed on Examples 1 to 5 and Comparative Examples 1 to 5 described above.
１．ベーマイト化の有無
X線回折装置（Bluker（株）製、D2 Phaser）で結晶相を測定した。未反応の原料が残らずベーマイトの結晶が認められる場合は○、未反応の原料が残っている場合は×と評価した。
２．カードハウス構造化の有無
試料をカーボンテープの上に張り付け、走査型電子顕微鏡（日本電子（株） JSM-7500FA）を用いて、粒子表面及び形状を観察した。カードハウス構造が認められるものを○、カードハウス構造が認められないか、殆どカードハウス構造が認められないものを×と評価した。
３．粒度（D50、D16、D84（いずれも体積基準））
0.2 %ヘキサメタりん酸ナトリウム水溶液に試料を分散させ、レーザー回折・散乱式の粒度分布測定装置（マイクロトラック・ベル（株）製 MT3000）を用いて粒度分布（体積基準）を測定し、D50、D16、D84の値を読み取った。
４．標準偏差SD、変動係数CV
次の式を用いて、標準偏差SD、変動係数CVを算出した。
標準偏差SD＝（D84－D16）/2 （式１）
変動係数CV =（標準偏差SD/D50）×100 （式２）
５．吸油量
試薬のあまに油（関東化学（株）製）を用いて、ＪＩＳ Ｋ５１０１－１３－１（２００４）の精製あまに油法に準じて測定した。測定手順は次のとおりである。
（１）試料2 gを秤量し、ガラス製の測定板の上に置いた。
（２）あまに油をスポイトから１回につき4～5滴ずつ徐々に加え、パレットナイフであまに油に試料を練り込んだ。
（３）上記（２）の操作を繰り返し行い、あまに油および試料の塊ができるところまで滴下を続けた。
（４）以後、あまに油を1滴ずつ滴下し、完全に混練するようにして繰り返し、ペーストが柔らかな硬さになったところを終点とした。
（５）下記の式を用いて、吸油量の値を求めた。
吸油量（g/100g）=（終点までに用いたあまに油の重量（g）/試料の重量（g））×100 （式４） ６．タップ密度
10mLのメスシリンダーに試料0.3g、0.5g又は1gをいれ、一定高さより一定速度で嵩の変化がなくなるまで落下させることによって充填した。充填後の体積の値を読み取り、次の式を用いてタップ密度の値を算出した。
タップ密度（g/cm3）=試料重量（g）/充填後の体積（cm3 ） （式５）
７．比表面積
全自動比表面積測定装置（マウンテック（株）製 Macsorb（登録商標） HM model-1200）を使用し、BET表面積の測定前に150℃で30分の真空加熱排気による前処理を行ってから、液体窒素温度近傍（77K）にてBET流動法（1点法）で測定した。
８．１％重量減少温度
示差熱・熱重量同時測定装置 (TG-DTA 2000SA、ブルカー・エイエックスエス（株）製）を用いて測定した。昇温速度は30℃/minとし、100℃を基準として1.00重量%減少した温度を読み取った。
９．熱伝導率
下記の所定のサイズの樹脂に試料を練込限界まで練り込み、樹脂組成物の熱伝導率を測定した。
（１）樹脂の種類：エポキシ樹脂（ビスフェノールA型）
（製品名：R140P、製造元：三井化学（株）製、25℃における粘度 12,000～15,000 cps）
（２）作製方法：205mLの紙コップにエポキシ樹脂30gを入れ、練込限界になるまで試料を徐々に配合し、自転・公転ミキサー（シンキー（株）製ARE-310）で混合する作業を繰り返した。試料を練込限界まで配合・混合後、2-エチル-4-メチルイミダゾール（和光純薬（株）社製）を0.6g加えて十分に混合・脱泡し、120℃で2時間加熱硬化した。得られた硬化物を目的とする形状に加工し、樹脂組成物の試験片を得た。
練込限界の試料の体積充填率は次の式により導出した。
試料の体積充填率（vol%）=（試料の体積（cm3）/（試料の体積（cm3）+エポキシ樹脂 の体積（cm3）））×100 （式６）
試料の体積（cm3）= 試料重量（g）/試料の密度（g/ cm3） （式７）
エポキシ樹脂の体積（cm3）= エポキシ樹脂の重量（g）/エポキシ樹脂の密度（g/cm3） （式８）
ベーマイトの密度：3.0 g/ cm3、エポキシ樹脂の密度：1.16 g/ cm3
（３）測定方法：熱線法（製品名：QTM-500、京都電子（株）製）
（４）樹脂組成物の試験片の形状：直径5ｃｍ、厚さ1.5ｃｍの円盤体
1. Presence or absence of boehmite formation
The crystal phase was measured with an X-ray diffractometer (D2 Phaser, manufactured by Bluker Co.). When no unreacted starting material remained and boehmite crystals were observed, it was evaluated as ◯, and when unreacted starting material remained, it was evaluated as x.
2. Presence or Absence of Card House Structure A sample was stuck on a carbon tape, and the particle surface and shape were observed using a scanning electron microscope (JSM-7500FA, manufactured by JEOL Ltd.). A sample with a card house structure was evaluated as ◯, and a sample with no card house structure or almost no card house structure was evaluated as x.
3. Particle size (D50, D16, D84 (both based on volume))
The sample is dispersed in 0.2% sodium hexametaphosphate aqueous solution, and the particle size distribution (volume basis) is measured using a laser diffraction/scattering particle size distribution measuring device (MT3000 manufactured by Microtrack Bell Co., Ltd.), D50, D16 , the value of D84 was read.
4. Standard deviation SD, coefficient of variation CV
Standard deviation SD and coefficient of variation CV were calculated using the following formulas.
Standard deviation SD = (D84-D16)/2 (Formula 1)
Coefficient of variation CV = (standard deviation SD/D50) x 100 (Formula 2)
5. Oil Absorption Measured according to the refined linseed oil method of JIS K5101-13-1 (2004) using linseed oil (manufactured by Kanto Kagaku Co., Ltd.) as a reagent. The measurement procedure is as follows.
(1) 2 g of sample was weighed and placed on a glass measuring plate.
(2) 4 to 5 drops of linseed oil were gradually added at a time from a dropper, and the sample was kneaded into the linseed oil with a palette knife.
(3) The above operation (2) was repeated, and dropping was continued until lumps of linseed oil and the sample were formed.
(4) Thereafter, the linseed oil was dropped drop by drop, and the mixture was thoroughly kneaded.
(5) The value of oil absorption was obtained using the following formula.
Oil absorption (g/100g) = (weight of linseed oil used up to the end point (g)/weight of sample (g)) x 100 (Formula 4)6. tap density
A sample of 0.3 g, 0.5 g or 1 g was placed in a 10 mL graduated cylinder and filled by dropping from a constant height at a constant speed until the change in volume disappeared. The value of the volume after filling was read, and the tap density value was calculated using the following formula.
Tap density (g/cm 3 ) = sample weight (g)/volume after filling (cm 3 ) (Formula 5)
7. Specific surface area Using a fully automatic specific surface area measuring device (Macsorb (registered trademark) HM model-1200 manufactured by Mountec Co., Ltd.), pretreatment by vacuum heating and exhausting at 150 ° C for 30 minutes before measuring the BET surface area. , was measured by the BET flow method (single-point method) near liquid nitrogen temperature (77K).
8.1% Weight Loss Temperature Measured using a simultaneous differential thermal/thermogravimetric analyzer (TG-DTA 2000SA, manufactured by Bruker AXS Co., Ltd.). The temperature was raised at a rate of 30°C/min, and the temperature at which the temperature decreased by 1.00% by weight from 100°C was read.
9. Thermal Conductivity A sample was kneaded into a resin having the following predetermined size up to the kneading limit, and the thermal conductivity of the resin composition was measured.
(1) Type of resin: epoxy resin (bisphenol A type)
(Product name: R140P, manufacturer: Mitsui Chemicals, Inc., viscosity at 25°C: 12,000-15,000 cps)
(2) Preparation method: Put 30 g of epoxy resin in a 205 mL paper cup, gradually mix the sample until the kneading limit is reached, and repeat the process of mixing with a rotation / revolution mixer (Thinky Co., Ltd. ARE-310). rice field. After blending and mixing the sample up to the kneading limit, 0.6 g of 2-ethyl-4-methylimidazole (manufactured by Wako Pure Chemical Industries, Ltd.) was added, thoroughly mixed and defoamed, and heat-cured at 120 ° C for 2 hours. . The resulting cured product was processed into a desired shape to obtain a test piece of the resin composition.
The volumetric filling rate of the kneading limit sample was derived from the following equation.
Sample volume filling rate (vol%) = (Sample volume (cm 3 ) / (Sample volume (cm 3 ) + Epoxy resin volume (cm 3 ))) × 100 (Formula 6)
Sample volume (cm 3 ) = sample weight (g)/sample density (g/cm 3 ) (Formula 7)
Epoxy resin volume (cm 3 ) = Epoxy resin weight (g)/Epoxy resin density (g/cm 3 ) (Formula 8)
Density of boehmite: 3.0 g/ cm3 , density of epoxy resin: 1.16 g/ cm3
(3) Measurement method: hot wire method (product name: QTM-500, manufactured by Kyoto Electronics Co., Ltd.)
(4) Shape of test piece of resin composition: disk with a diameter of 5 cm and a thickness of 1.5 cm
表１に実施例及び比較例の製造方法を示し、表２及び表３に実施例及び比較例の各種試験の結果を示した。 Table 1 shows the production methods of Examples and Comparative Examples, and Tables 2 and 3 show the results of various tests of Examples and Comparative Examples.
図１～図９は、実施例１～実施例５及び比較例１～比較例４のＳＥＭ写真である。また、図１０は、実施例２の鱗片状ベーマイト凝集体の断面を示すＳＥＭ写真であり、図１１は比較例４の鱗片状ベーマイト凝集体の断面を示すＳＥＭ写真である。なお、図１～図９の下段は、上段の一部を拡大したＳＥＭ写真である。これらのＳＥＭ写真を参照の上、上記の結果に基づいて以下のことが解析できる。 1 to 9 are SEM photographs of Examples 1 to 5 and Comparative Examples 1 to 4. FIG. 10 is a SEM photograph showing a cross section of the scale-like boehmite aggregates of Example 2, and FIG. 11 is a SEM photograph showing a cross section of the scale-like boehmite aggregates of Comparative Example 4. FIG. 1 to 9 are SEM photographs in which a part of the upper part is enlarged. With reference to these SEM photographs, the following can be analyzed based on the above results.
・各実施例の下段のＳＥＭ写真に示すように、鱗片状ベーマイト凝集体は、密なカードハウス構造を形成している。また、各実施例の上段のＳＥＭ写真に示すように、鱗片状ベーマイト凝集体は、粒度のばらつきが小さく、粒度の揃った粒子である。図１０の実施例２の鱗片状ベーマイト凝集体の断面のＳＥＭ写真から、実施例２の鱗片状ベーマイト凝集体は、密なカードハウス構造を形成していることが分かる。また、図１１の比較例４の鱗片状ベーマイト凝集体の断面のＳＥＭ写真から、比較例４の鱗片状ベーマイト凝集体は嵩高いカードハウス構造を形成していることが分かる。
一方、比較例１～比較例３は、カードハウス構造の凝集を形成しない鱗片状ベーマイトの結晶が分散した鱗片状ベーマイト粒子であることが分かる。
・実施例１と比較例１は、原料の水酸化アルミニウムの平均粒径が相違する以外、同じ方法で製造されたものである。実施例１は、カードハウス構造を形成しているため、吸油量は空隙が少ない比較例１より高い。一方、カードハウス構造が密であるため、実施例１の吸油量は、嵩高いカードハウス構造を有する鱗片状ベーマイト凝集体の比較例４の約５０％である。また、変動係数ＣＶの違いから、実施例１の方が比較例１より粒度のバラツキが小さく、粒度の揃った粒子であることが分かる。さらに、実施例１は、カードハウス構造が密であるため樹脂に充填し易く、樹脂組成物に練込限界まで充填した体積充填率は比較例１に比べて高く、樹脂組成物の熱伝導率も高くなる。また、実施例１のタップ密度は、比較例１のタップ密度より高く、実施例１は比較例１に比べ飛散し難く、ハンドリング性に優れている。
原料の水酸化アルミニウムの平均粒径が相違する以外、同じ方法で製造された実施例４と比較例２及び実施例５と比較例３についても、上記とほぼ同様に解析できる。特に、実施例４のタップ密度は比較例２のタップ密度の約４倍で、また、実施例５のタップ密度は比較例３のタップ密度の１０倍であるため、実施例４は比較例２に比べ飛散し難く、また、実施例５は比較例３に比べ飛散し難く、実施例４及び実施例５はハンドリング牲に優れている。
・比較例４は、原料の添加剤を水酸化ナトリウムに換えて炭酸ナトリウムとした以外、実施例２とほぼ同様な方法で製造されたもので、図９に示すように、鱗片状ベーマイトの結晶同士が凝集した嵩高いカードハウス構造を有する鱗片状ベーマイト凝集体である。また、比較例４は、カードハウス構造が嵩高いため、樹脂に充填しにくく、樹脂組成物に練込限界まで充填した体積充填率は実施例に比べて低く、熱伝導率も低い。
このように、カードハウス構造が嵩高いか密かは、鱗片状ベーマイト凝集体を樹脂組成物に練込限界まで充填した体積充填率の違い及び熱伝導率の違いからも分かる。
・比較例５は、水懸濁液を静置した以外実施例３とほぼ同様の方法で製造したものである。比較例５は、成型物となり、ベーマイト化を確認できたものの、他の試験は十分には行えなかった。
・結晶化が進んだベーマイトの比表面積は、数ｍ２／ｇ～数十ｍ２／ｇを呈する。実施例及び比較例の鱗片状ベーマイトの比表面積は、数ｍ２／ｇ～数十ｍ２／ｇであり、実施例及び比較例のいずれも結晶性の高いマイクロサイズのベーマイトであることが分かる。
・実施例及び比較例のいずれの１％重量減少温度も４２０℃を越えているのは、実施例も比較例も製造に当たり有機系のバインダーを使用していないこと及びベーマイトの結晶性が高いことに起因する。
- As shown in the lower SEM photographs of each example, the scale-like boehmite aggregates form a dense card house structure. In addition, as shown in the upper SEM photographs of each example, the scaly boehmite aggregates are particles of uniform particle size with little variation in particle size. From the SEM photograph of the cross section of the scale-like boehmite aggregates of Example 2 in FIG. 10, it can be seen that the scale-like boehmite aggregates of Example 2 form a dense card house structure. Also, from the SEM photograph of the cross section of the scale-like boehmite aggregates of Comparative Example 4 in FIG. 11, it can be seen that the scale-like boehmite aggregates of Comparative Example 4 form a bulky card house structure.
On the other hand, it can be seen that Comparative Examples 1 to 3 are scaly boehmite particles in which scaly boehmite crystals that do not form agglomerates of a card house structure are dispersed.
- Example 1 and Comparative Example 1 were produced by the same method except that the average particle size of aluminum hydroxide as a raw material was different. Since Example 1 has a card house structure, the oil absorption is higher than that of Comparative Example 1, which has less voids. On the other hand, since the housed card structure is dense, the oil absorption of Example 1 is about 50% of that of Comparative Example 4, which is a scale-like boehmite aggregate having a bulky housed card structure. Also, from the difference in the coefficient of variation CV, it can be seen that Example 1 has smaller variation in particle size than Comparative Example 1, and the particles have a uniform particle size. Furthermore, in Example 1, since the card house structure is dense, it is easy to fill the resin, and the volume filling rate when the resin composition is filled to the kneading limit is higher than that in Comparative Example 1, and the thermal conductivity of the resin composition also higher. Moreover, the tap density of Example 1 is higher than that of Comparative Example 1, and Example 1 is less likely to scatter than Comparative Example 1 and is excellent in handleability.
Example 4 and Comparative Example 2, and Example 5 and Comparative Example 3, which were produced in the same manner except that the average particle size of aluminum hydroxide used as the raw material was different, can be analyzed in substantially the same manner as described above. In particular, the tap density of Example 4 is about four times that of Comparative Example 2, and the tap density of Example 5 is ten times that of Comparative Example 3. In addition, Example 5 is less likely to scatter than Comparative Example 3, and Examples 4 and 5 are excellent in handleability.
・Comparative Example 4 was produced in substantially the same manner as in Example 2, except that sodium carbonate was used instead of sodium hydroxide as a raw material additive. It is a scale-like boehmite aggregate having a bulky card house structure in which the bodies are aggregated together. In addition, in Comparative Example 4, since the card house structure is bulky, it is difficult to fill the resin, and the volume filling rate when the resin composition is filled up to the kneading limit is lower than in Examples, and the thermal conductivity is also low.
Thus, whether the card house structure is bulky or not can be understood from the difference in the volumetric filling rate and the thermal conductivity when the scale-like boehmite aggregates are filled into the resin composition to the kneading limit.
- Comparative Example 5 was produced in substantially the same manner as in Example 3, except that the water suspension was allowed to stand. In Comparative Example 5, a molded product was obtained, and although boehmite conversion was confirmed, other tests could not be performed sufficiently.
・The specific surface area of boehmite that has advanced crystallization is several m 2 /g to several tens of m 2 /g. The specific surface area of the scale-like boehmite of Examples and Comparative Examples is several m 2 /g to several tens of m 2 /g, and it can be seen that both of Examples and Comparative Examples are micro-sized boehmite with high crystallinity. .
・The reason why the 1% weight loss temperature of both Examples and Comparative Examples exceeds 420°C is that organic binders are not used in the production of Examples and Comparative Examples, and the crystallinity of boehmite is high. caused by.
本発明の鱗片状ベーマイト凝集体は、樹脂などの熱伝導性の充填剤として好適である。 The scale-like boehmite aggregates of the present invention are suitable as thermally conductive fillers such as resins.
Claims (5)
標準偏差ＳＤ＝（Ｄ８４－Ｄ１６）／２ （式１）
変動係数ＣＶ＝（標準偏差ＳＤ／Ｄ５０）×１００ （式２） 2. The scale-like boehmite aggregate according to claim 1, wherein the coefficient of variation CV calculated using the following formula is 40% or less.
Standard deviation SD = (D84-D16) / 2 (Formula 1)
Coefficient of variation CV = (standard deviation SD / D50) × 100 (Formula 2)
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