JP6127353B2 - Insulating material and manufacturing method thereof - Google Patents
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- 239000011810 insulating material Substances 0.000 title claims description 111
- 238000004519 manufacturing process Methods 0.000 title claims description 13
- 239000002245 particle Substances 0.000 claims description 116
- 239000011148 porous material Substances 0.000 claims description 96
- 229910044991 metal oxide Inorganic materials 0.000 claims description 52
- 150000004706 metal oxides Chemical class 0.000 claims description 52
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 34
- 238000010438 heat treatment Methods 0.000 claims description 32
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 28
- 239000011163 secondary particle Substances 0.000 claims description 27
- 239000011164 primary particle Substances 0.000 claims description 26
- 239000000835 fiber Substances 0.000 claims description 22
- 239000000463 material Substances 0.000 claims description 18
- 238000000034 method Methods 0.000 claims description 18
- 238000005245 sintering Methods 0.000 claims description 18
- 239000006185 dispersion Substances 0.000 claims description 17
- 239000000377 silicon dioxide Substances 0.000 claims description 14
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 claims description 12
- 230000005855 radiation Effects 0.000 claims description 12
- KZHJGOXRZJKJNY-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O KZHJGOXRZJKJNY-UHFFFAOYSA-N 0.000 claims description 11
- 229910052863 mullite Inorganic materials 0.000 claims description 11
- 239000003112 inhibitor Substances 0.000 claims description 9
- 230000000737 periodic effect Effects 0.000 claims description 8
- 238000010304 firing Methods 0.000 claims description 6
- 239000007788 liquid Substances 0.000 claims description 4
- 230000001629 suppression Effects 0.000 claims description 4
- 229910052693 Europium Inorganic materials 0.000 claims description 3
- 229910052772 Samarium Inorganic materials 0.000 claims description 3
- OGPBJKLSAFTDLK-UHFFFAOYSA-N europium atom Chemical compound [Eu] OGPBJKLSAFTDLK-UHFFFAOYSA-N 0.000 claims description 3
- 229910052746 lanthanum Inorganic materials 0.000 claims description 3
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 claims description 3
- KZUNJOHGWZRPMI-UHFFFAOYSA-N samarium atom Chemical compound [Sm] KZUNJOHGWZRPMI-UHFFFAOYSA-N 0.000 claims description 3
- RUDFQVOCFDJEEF-UHFFFAOYSA-N yttrium(III) oxide Inorganic materials [O-2].[O-2].[O-2].[Y+3].[Y+3] RUDFQVOCFDJEEF-UHFFFAOYSA-N 0.000 claims description 2
- 230000002401 inhibitory effect Effects 0.000 claims 1
- 230000000052 comparative effect Effects 0.000 description 8
- 238000005259 measurement Methods 0.000 description 6
- 238000011156 evaluation Methods 0.000 description 5
- 239000012784 inorganic fiber Substances 0.000 description 5
- 238000012546 transfer Methods 0.000 description 5
- 238000009413 insulation Methods 0.000 description 4
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 4
- 229910052753 mercury Inorganic materials 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000000465 moulding Methods 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 239000007789 gas Substances 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 229910052596 spinel Inorganic materials 0.000 description 3
- 239000011029 spinel Substances 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 238000007872 degassing Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000000395 magnesium oxide Substances 0.000 description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- GFQYVLUOOAAOGM-UHFFFAOYSA-N zirconium(iv) silicate Chemical compound [Zr+4].[O-][Si]([O-])([O-])[O-] GFQYVLUOOAAOGM-UHFFFAOYSA-N 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 229910020068 MgAl Inorganic materials 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 1
- 239000005083 Zinc sulfide Substances 0.000 description 1
- GEIAQOFPUVMAGM-UHFFFAOYSA-N ZrO Inorganic materials [Zr]=O GEIAQOFPUVMAGM-UHFFFAOYSA-N 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- JRPBQTZRNDNNOP-UHFFFAOYSA-N barium titanate Chemical compound [Ba+2].[Ba+2].[O-][Ti]([O-])([O-])[O-] JRPBQTZRNDNNOP-UHFFFAOYSA-N 0.000 description 1
- 229910002113 barium titanate Inorganic materials 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 229910000423 chromium oxide Inorganic materials 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 239000006260 foam Substances 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000012774 insulation material Substances 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000002459 porosimetry Methods 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000000352 supercritical drying Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 229910052727 yttrium Inorganic materials 0.000 description 1
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 description 1
- 229910052984 zinc sulfide Inorganic materials 0.000 description 1
- DRDVZXDWVBGGMH-UHFFFAOYSA-N zinc;sulfide Chemical compound [S-2].[Zn+2] DRDVZXDWVBGGMH-UHFFFAOYSA-N 0.000 description 1
- 229910052845 zircon Inorganic materials 0.000 description 1
Landscapes
- Thermal Insulation (AREA)
- Compositions Of Oxide Ceramics (AREA)
Description
本発明は、断熱材及びその製造方法に関する。 The present invention relates to a heat insulating material and a method for manufacturing the same.
近年の省エネ需要の高まりから、工業炉や焼却炉、工場等の断熱が非常に重要な課題となり、断熱材のさらなる性能向上が求められている。固体酸化物燃料電池電極や半導体ウエハーの加熱炉等では、最高加熱温度が１２００℃を超え、蛍光体素子、ガラス、製鉄用加熱炉等では、最高加熱温度が１４００℃を超える。しかしながら、１２００℃を超える用途に使用でき、なおかつ低熱伝導率を兼ね備えた断熱材は未だ開発されていない。 With the recent increase in energy-saving demand, heat insulation in industrial furnaces, incinerators, factories, etc. has become a very important issue, and further performance improvement of heat insulating materials is required. The maximum heating temperature exceeds 1200 ° C. in a solid oxide fuel cell electrode, a semiconductor wafer heating furnace, and the like, and the maximum heating temperature exceeds 1400 ° C. in a phosphor element, glass, a steel heating furnace, and the like. However, a heat insulating material that can be used for applications exceeding 1200 ° C. and has low thermal conductivity has not been developed yet.
特許文献１は、多孔性の断熱材を開示している。この断熱材はスピネル質セラミックスからなる。 Patent document 1 is disclosing the porous heat insulating material. This heat insulating material is made of spinel ceramics.
本発明は、上記課題に鑑みて為されたものであって、熱伝導率が低い断熱材及びその製造方法を提供することをその目的の一つとする。 This invention is made | formed in view of the said subject, Comprising: It aims at providing the heat insulating material with low heat conductivity, and its manufacturing method.
本発明によれば、以下の断熱材及びその製造方法が提供される。
１．１４００℃で２４時間加熱した後、全ての気孔の容積の合計に対する、径４００ｎｍ以下の気孔の容積の合計の割合が、５％以上であり、周期加熱法で測定した１０００℃における熱伝導率が０．１５Ｗ／（ｍ・Ｋ）未満である断熱材。
２．１次粒子である金属酸化物粒子が凝集した２次粒子で構成される断熱材であって、
前記２次粒子内と前記２次粒子間に細孔があり、
前記金属酸化物粒子が、アルミナ成分を６０重量％以上含み、前記１次粒子の平均粒径が１０ｎｍ〜１０００ｎｍである１記載の断熱材。
３．焼成前、全ての気孔の容積の合計に対する３００ｎｍ以下の気孔の容積の合計の割合が５％以上であり、かつ
３００ｎｍ以下の細孔容積に占める５０ｎｍ以上３００ｎｍ以下の細孔容積の割合が、５０％〜９５％である１又は２記載の断熱材。
４．前記金属酸化物粒子が、アルミナ粒子又はムライト粒子である１又は２記載の断熱材。
５．前記２次粒子の平均粒径が１００ｎｍ〜１０００ｎｍである２〜４のいずれか記載の断熱材。
６．１４００℃で２４時間加熱した後、全ての気孔の容積の合計に対する、径３００ｎｍ以下の気孔の容積の合計の割合が、１５％以上であり、周期加熱法で測定した１０００℃における熱伝導率が０．１０Ｗ／（ｍ・Ｋ）以下である１〜５のいずれか記載の断熱材。
７．平均粒径が１０ｎｍ〜１０００ｎｍの１次粒子である金属酸化物粒子が分散した第１の分散液を作製し、
前記第１の分散液のｐＨを調整して、前記１次粒子が凝集した２次粒子が分散した第２の分散液を作製し、
前記第２の分散液を凍結乾燥して凝集体を作製し、
前記凝集体を、プレス成形する、断熱材の製造方法。
８．平均粒径が１００ｎｍを超える、アルミナ成分を６０重量％以上含む金属酸化物粒子と、
焼結抑制材を含む１記載の断熱材。
９．前記焼結抑制材が、ジルコニア、ランタン、イットリア、サマリウム及びユウロピウムから選択される１以上である８記載の断熱材。
１０．前記金属酸化物粒子が、シリカ成分を含む８又は９記載の断熱材。
１１．平均粒径が１００ｎｍ以上である、アルミナ成分を６０〜８０重量％とシリカ成分を４０〜２０重量％含む金属酸化物粒子を含む１記載の断熱材。
１２．前記金属酸化物粒子が、ムライト粒子である１１記載の断熱材。
１３．さらに、焼結抑制材を含む１１又は１２記載の断熱材。
１４．前記金属酸化物粒子の平均粒径が１００ｎｍを超えて１０００ｎｍ以下である８〜１３のいずれか記載の断熱材。
１５．粒径１００ｎｍを超えて１０００ｎｍ以下の金属酸化物粒子が、前記金属酸化物粒子の全ての５０容積％以上である１４記載の断熱材。
１６．さらに、繊維及び／又は輻射散乱材を含む１〜６及び８〜１５のいずれか記載の断熱材。
According to this invention, the following heat insulating materials and its manufacturing method are provided.
1. After heating at 400 ° C. for 24 hours, the ratio of the total volume of pores having a diameter of 400 nm or less to the total volume of all pores is 5% or more, and the heat conduction at 1000 ° C. measured by the periodic heating method. A heat insulating material having a rate of less than 0.15 W / (m · K).
2. A heat insulating material composed of secondary particles in which metal oxide particles as primary particles are aggregated,
There are pores in the secondary particles and between the secondary particles,
The heat insulating material according to 1, wherein the metal oxide particles contain 60% by weight or more of an alumina component, and the average particle diameter of the primary particles is 10 nm to 1000 nm.
3. Before firing, the ratio of the total pore volume of 300 nm or less to the total volume of all pores is 5% or more, and the ratio of the pore volume of 50 nm to 300 nm in the pore volume of 300 nm or less is 50% or less. The heat insulating material of 1 or 2 which is% -95%.
4). The heat insulating material according to 1 or 2, wherein the metal oxide particles are alumina particles or mullite particles.
5. The heat insulating material in any one of 2-4 whose average particle diameter of the said secondary particle is 100 nm-1000 nm.
6. After heating at 1400 ° C. for 24 hours, the ratio of the total volume of pores having a diameter of 300 nm or less to the total volume of all pores is 15% or more, and heat conduction at 1000 ° C. measured by a periodic heating method. The heat insulating material in any one of 1-5 whose rate is 0.10 W / (m * K) or less.
7). A first dispersion liquid in which metal oxide particles that are primary particles having an average particle diameter of 10 nm to 1000 nm are dispersed is prepared,
Adjusting the pH of the first dispersion to produce a second dispersion in which the secondary particles in which the primary particles are aggregated are dispersed;
The second dispersion is lyophilized to produce an aggregate,
A method for producing a heat insulating material, wherein the aggregate is press-molded.
8). Metal oxide particles having an average particle size of more than 100 nm and containing 60% by weight or more of an alumina component;
2. The heat insulating material according to 1, including a sintering inhibitor.
9. 9. The heat insulating material according to 8, wherein the sintering inhibitor is one or more selected from zirconia, lanthanum, yttria, samarium and europium.
10. The heat insulating material according to 8 or 9, wherein the metal oxide particles contain a silica component.
11. 2. The heat insulating material according to 1, comprising metal oxide particles having an average particle size of 100 nm or more and containing 60 to 80% by weight of an alumina component and 40 to 20% by weight of a silica component.
12 12. The heat insulating material according to 11, wherein the metal oxide particles are mullite particles.
13. Furthermore, the heat insulating material of 11 or 12 containing a sintering suppression material.
14 The heat insulating material according to any one of 8 to 13, wherein an average particle diameter of the metal oxide particles exceeds 100 nm and is 1000 nm or less.
15. 15. The heat insulating material according to 14, wherein the metal oxide particles having a particle size of more than 100 nm and not more than 1000 nm are 50% by volume or more of all the metal oxide particles.
16. Furthermore, the heat insulating material in any one of 1-6 and 8-15 containing a fiber and / or a radiation scattering material.
本発明によれば、熱伝導率が低い断熱材及びその製造方法を提供することができる。 ADVANTAGE OF THE INVENTION According to this invention, a heat insulating material with low heat conductivity and its manufacturing method can be provided.
本発明者らは、耐熱温度が１２００℃を超える、１３００℃、さらには１４００℃に達する断熱材の開発を鋭意研究した。
多孔性断熱材の伝熱（熱伝導率）は、気体分子の伝熱、固体同士の接触、輻射による伝導等により決まる。多孔性断熱材は固体量が少なく、気体分子の伝熱が大きな影響を及ぼす。気体分子の伝熱は気孔（細孔）径が平均自由行程以下の場合に抑制できる。高温域では、平均自由行程は大きくなる。従って、多孔性断熱材の場合、径が平均自由行程以下の気孔を多く含み、かつその気孔を高温で維持することが重要である。
本発明者らは、従来の多孔性断熱材では１２００℃を超える高温では、気孔がつぶれ断熱性が損なわれることを見い出した。
The present inventors diligently studied the development of a heat insulating material having a heat-resistant temperature exceeding 1200 ° C., reaching 1300 ° C., and further reaching 1400 ° C.
The heat transfer (thermal conductivity) of the porous heat insulating material is determined by heat transfer of gas molecules, contact between solids, conduction by radiation, and the like. The porous heat insulating material has a small amount of solids, and the heat transfer of gas molecules has a great influence. Heat transfer of gas molecules can be suppressed when the pore (pore) diameter is equal to or less than the mean free path. In the high temperature range, the mean free path becomes large. Therefore, in the case of a porous heat insulating material, it is important to contain many pores having a diameter equal to or less than the mean free path and to maintain the pores at a high temperature.
The present inventors have found that the conventional porous heat insulating material collapses the pores at a high temperature exceeding 1200 ° C. and impairs the heat insulating property.
本発明者らは、平均粒径がサブミクロンのアルミナを主成分とする金属酸化物粒子を用いた多孔性断熱材は、微細な気孔を多く含みかつ高温に曝された後でも十分な量の気孔が残ることを見い出した。更には、本発明者らは、アルミナ成分以外の成分又は粒子を添加することにより、アルミナ同士の焼結を抑制して、気孔が残ることを見い出した。 The inventors of the present invention have described that a porous heat insulating material using metal oxide particles mainly composed of alumina having an average particle size of submicron contains a large amount of fine pores and has a sufficient amount even after being exposed to a high temperature. I found that pores remained. Furthermore, the present inventors have found that pores remain by suppressing sintering between aluminas by adding components or particles other than the alumina component.
また、本発明者らは、１次粒子間で形成される細孔と、１次粒子が凝集した２次粒子間で形成される細孔を含む多孔性断熱材は、微細な気孔を多く含みかつ高温に曝された後でも焼結を抑制して十分な量の気孔が残ることを見い出した。
本発明はこれら知見により完成した。
In addition, the inventors of the present invention have a porous insulating material including pores formed between primary particles and pores formed between secondary particles in which the primary particles are aggregated, and includes many fine pores. It was also found that a sufficient amount of pores remained by suppressing sintering even after exposure to high temperatures.
The present invention has been completed based on these findings.
本発明の断熱材は、１４００℃で２４時間加熱した後、全ての気孔の容積の合計に対する、径４００ｎｍ以下の気孔の容積の合計の割合は、好ましくは５％以上、より好ましくは１０％以上、さらに好ましくは１５％以上である。上限は限定されないが、通常８０％以下である。
本発明において、気孔の容積は実施例に記載の方法で測定できる。
After the heat insulating material of the present invention is heated at 1400 ° C. for 24 hours, the ratio of the total volume of pores having a diameter of 400 nm or less to the total volume of all pores is preferably 5% or more, more preferably 10% or more. More preferably, it is 15% or more. Although an upper limit is not limited, Usually, it is 80% or less.
In the present invention, the pore volume can be measured by the method described in Examples.
本発明の断熱材の加熱前の全ての気孔の容積の総計は、通常、６０容積％以上であり、好ましくは７５容積％以上である。上限は限定されないが、通常９８容積％以下である。
また、断熱材の１４００℃で２４時間加熱した後の気孔容積の総計は、通常、６０容積％以上であり、好ましくは７５容積％以上である。上限は限定されないが、通常９０容積％以下である。全ての気孔の容積は、焼成前後で変わらない（収縮しない）ことが好ましい。
The total volume of all pores before heating of the heat insulating material of the present invention is usually 60% by volume or more, and preferably 75% by volume or more. Although an upper limit is not limited, Usually, it is 98 volume% or less.
Further, the total pore volume of the heat insulating material after heating at 1400 ° C. for 24 hours is usually 60% by volume or more, and preferably 75% by volume or more. Although an upper limit is not limited, Usually, it is 90 volume% or less. It is preferable that the volume of all pores does not change (does not shrink) before and after firing.
本発明の断熱材の加熱前の全ての気孔の容積の合計に対する、径４００ｎｍ以下の気孔の容積の合計の割合は、好ましくは１０％以上、より好ましくは２５％以上、さらに好ましくは３０％以上である。上限は限定されないが、通常９０％以下又は８０％以下である。 The ratio of the total volume of pores having a diameter of 400 nm or less to the total volume of all pores before heating of the heat insulating material of the present invention is preferably 10% or more, more preferably 25% or more, and further preferably 30% or more. It is. Although an upper limit is not limited, Usually, it is 90% or less or 80% or less.
このような断熱材を具体的に以下に示す。
尚、本願明細書において、数値範囲のＡ〜Ｂは、Ａ以上Ｂ以下を意味する。
Such a heat insulating material is specifically shown below.
In addition, in this-application specification, A-B of a numerical range means A or more and B or less.
［第１の発明］
第１の発明の第１の態様による断熱材は、アルミナ成分を６０重量％以上含む金属酸化物粒子と焼結抑制剤から形成できる。この金属酸化物粒子の平均粒径は例えば１００ｎｍを超える。好ましくは１００ｎｍを超えて１０００ｎｍ以下である。平均粒径は好ましくは１５０ｎｍ〜１０００ｎｍであり、より好ましくは２００ｎｍ〜５００ｎｍである。フュームドアルミナは平均粒径は通常数十ｎｍであるので、適さない。
[First invention]
The heat insulating material according to the first aspect of the first invention can be formed from metal oxide particles containing 60% by weight or more of an alumina component and a sintering inhibitor. The average particle diameter of the metal oxide particles exceeds 100 nm, for example. Preferably it is more than 100 nm and 1000 nm or less. The average particle size is preferably 150 nm to 1000 nm, more preferably 200 nm to 500 nm. Fumed alumina is not suitable because the average particle size is usually several tens of nanometers.
本明細書において、平均粒径は、ランダムに約１００個の粒子について、透過型電子顕微鏡（Ｔｒａｎｓｍｉｓｓｉｏｎ Ｅｌｅｃｔｒｏｎ Ｍｉｃｒｏｓｃｏｐｅ；ＴＥＭ）又は電界放出形走査電子顕微鏡（Ｆｉｅｌｄ Ｅｍｉｓｓｉｏｎ Ｓｃａｎｎｉｎｇ Ｅｌｅｃｔｒｏｎ Ｍｉｃｒｏｓｃｏｐｅ；ＦＥ−ＳＥＭ）で粒子径（直径又は長径）を観察して求める。 In the present specification, the average particle size is about 100 particles at random using a transmission electron microscope (TEM) or a field emission scanning electron microscope (FE-SEM). Obtained by observing the diameter (diameter or major axis).
好ましくは、１００ｎｍを超える（好ましくは１０００ｎｍ以下）粒径の金属酸化物粒子の容積の合計が、金属酸化物粒子の全ての合計の容積の５０％以上である。より好ましくは８０％以上、さらに好ましくは９０％以上、特に好ましくは９５％以上である。 Preferably, the total volume of metal oxide particles having a particle size exceeding 100 nm (preferably 1000 nm or less) is 50% or more of the total volume of all metal oxide particles. More preferably, it is 80% or more, More preferably, it is 90% or more, Most preferably, it is 95% or more.
金属酸化物粒子は、アルミナ成分を、例えば、８０重量％以上、９０重量％以上、又は９９重量％以上含むことができる。
金属酸化物粒子は、アルミナ成分以外の成分を含むことができる。例えば、アルミナ成分とシリカ成分を含む粒子を用いることができる。アルミナ成分を６０〜８０重量％とシリカ成分を４０〜２０重量％含む金属酸化物粒子又はアルミナ成分を６５〜７５重量％とシリカ成分を３５〜２５重量％含む金属酸化物粒子を用いることができる。例えばムライト粒子を用いることができる。
金属酸化物粒子は２種以上混合して用いてもよい。
The metal oxide particles can contain an alumina component, for example, 80% by weight or more, 90% by weight or more, or 99% by weight or more.
The metal oxide particles can contain components other than the alumina component. For example, particles containing an alumina component and a silica component can be used. Metal oxide particles containing 60 to 80 wt% alumina component and 40 to 20 wt% silica component, or metal oxide particles containing 65 to 75 wt% alumina component and 35 to 25 wt% silica component can be used. . For example, mullite particles can be used.
Two or more kinds of metal oxide particles may be mixed and used.
焼結抑制材として、ジルコニア、ランタン、イットリウム、サマリウム、ユウロピウム等の粒子を含むことができる。焼結抑制材を含むと、粒子同士の焼結を阻害することができ好ましい。
これら粒子の粒径は、限定されないが、０．０１μｍ〜２μｍである。
As a sintering inhibitor, particles such as zirconia, lanthanum, yttrium, samarium, and europium can be included. Including a sintering inhibitor is preferable because it can inhibit sintering of particles.
The particle size of these particles is not limited, but is 0.01 μm to 2 μm.
第１の発明の第２の態様による断熱材は、アルミナ成分を６０〜８０重量％とシリカ成分を４０〜２０重量％含む金属酸化物粒子から形成できる。好ましくはアルミナ成分を６５〜７５重量％とシリカ成分を３５〜２５重量％含む金属酸化物粒子から形成する。金属酸化物粒子は２種以上混合して用いてもよい。例えばムライト粒子を用いることができる。 The heat insulating material according to the second aspect of the first invention can be formed from metal oxide particles containing 60 to 80% by weight of the alumina component and 40 to 20% by weight of the silica component. Preferably, it is formed from metal oxide particles containing 65 to 75% by weight of the alumina component and 35 to 25% by weight of the silica component. Two or more kinds of metal oxide particles may be mixed and used. For example, mullite particles can be used.
この金属酸化物粒子の平均粒径は例えば１００ｎｍ以上又は１００ｎｍを超える。好ましくは１００ｎｍを超えて１０００ｎｍ以下である。平均粒径は好ましくは１５０ｎｍ〜１０００ｎｍであり、より好ましくは２００ｎｍ〜５００ｎｍである。 The average particle diameter of the metal oxide particles is, for example, 100 nm or more or more than 100 nm. Preferably it is more than 100 nm and 1000 nm or less. The average particle size is preferably 150 nm to 1000 nm, more preferably 200 nm to 500 nm.
好ましくは、１００ｎｍ以上又は１００ｎｍを超える（好ましくは１０００ｎｍ以下）粒径の金属酸化物粒子の容積の合計が、金属酸化物粒子の全ての合計の容積の５０％以上である。より好ましくは８０％以上、さらに好ましくは９０％以上、特に好ましくは９５％以上である。 Preferably, the total volume of metal oxide particles having a particle diameter of 100 nm or more or more than 100 nm (preferably 1000 nm or less) is 50% or more of the total volume of all metal oxide particles. More preferably, it is 80% or more, More preferably, it is 90% or more, Most preferably, it is 95% or more.
さらに、金属酸化物粒子の他に、焼結抑制材を含むことができる。 Furthermore, in addition to the metal oxide particles, a sintering inhibitor can be included.
第１の発明の断熱材は、さらに、繊維を含んでもよい。好ましくは無機繊維を含む。繊維は、成形体を補強できるものであれば特に限られない。 The heat insulating material of the first invention may further contain fibers. Preferably inorganic fiber is included. The fiber is not particularly limited as long as it can reinforce the molded body.
無機繊維は、例えば、シリカ−アルミナ繊維、シリカ−アルミナ−マグネシア繊維、アルミナ繊維、ジルコニア繊維、生体溶解性無機繊維からなる群より選択される１種以上である。好ましくはアルミナ繊維である。
生体溶解性繊維として、ＳｉＯ２、Ａｌ２Ｏ３とＺｒＯ２との合計が５０〜８２重量％、ＣａＯとＭｇＯとの合計が１８〜５０重量％の組成の無機繊維を例示できる。また、ＳｉＯ２が５０〜８２重量％、ＣａＯとＭｇＯとの合計が１０〜４３重量％の組成の無機繊維も例示できる。本発明の使用に好適な生体溶解性繊維は、１３００℃において、収縮率が５％以下の繊維である。例えば、特許公報５６３４６３７号に記載の繊維を挙げられる。
The inorganic fiber is, for example, one or more selected from the group consisting of silica-alumina fiber, silica-alumina-magnesia fiber, alumina fiber, zirconia fiber, and biosoluble inorganic fiber. Alumina fibers are preferred.
Examples of the biosoluble fiber include inorganic fibers having a composition in which the total of SiO 2 , Al 2 O 3 and ZrO 2 is 50 to 82% by weight, and the total of CaO and MgO is 18 to 50% by weight. Further, SiO 2 is 50 to 82 wt%, the inorganic fibers of the composition total of 10 to 43 wt% of CaO and MgO can also be exemplified. A biosoluble fiber suitable for use in the present invention is a fiber having a shrinkage of 5% or less at 1300 ° C. For example, the fiber of patent gazette 5634637 is mentioned.
繊維の平均繊維長は、例えば、０．５ｍｍ以上、２０ｍｍ以下でよく、１ｍｍ以上、１０ｍｍ以下である。繊維の平均繊維径は、例えば、１μｍ以上、２０μｍ以下でよく、２μｍ以上、１５μｍ以下である。 The average fiber length of the fibers may be, for example, 0.5 mm or more and 20 mm or less, and is 1 mm or more and 10 mm or less. The average fiber diameter of the fibers may be, for example, 1 μm or more and 20 μm or less, and is 2 μm or more and 15 μm or less.
また、第１の発明の断熱材は、輻射散乱材を含むことができる。輻射散乱材は、輻射による伝熱を低減するものであれば特に限られない。輻射散乱材は、例えば、炭化珪素、ジルコニア、珪酸ジルコニウム（ジルコン）、チタニア、酸化鉄、酸化クロム、硫化亜鉛、チタン酸バリウムからなる群より選択される１種以上である。 Moreover, the heat insulating material of 1st invention can contain a radiation-scattering material. The radiation scattering material is not particularly limited as long as it reduces heat transfer by radiation. The radiation scattering material is at least one selected from the group consisting of silicon carbide, zirconia, zirconium silicate (zircon), titania, iron oxide, chromium oxide, zinc sulfide, and barium titanate.
輻射散乱材の平均粒径は、例えば、１μｍ超、５０μｍ以下でよく、１μｍ超、２０μｍ以下である。輻射散乱材は、遠赤外線反射性のものが好ましく、例えば、１μｍ以上の波長の光に対する比屈折率が１．２５以上であるものが好ましい。 The average particle diameter of the radiation scattering material may be, for example, more than 1 μm and 50 μm or less, and more than 1 μm and 20 μm or less. The radiation scattering material is preferably a far-infrared reflective material, for example, a material having a relative refractive index of 1.25 or more for light having a wavelength of 1 μm or more.
断熱材の原料に含まれる金属酸化物粒子の量は、所望の特性を実現する範囲であれば特に限られない。断熱材は、例えば、５０〜１００重量％、６０〜９８重量％、７０〜９５重量％、又は８０〜９０重量％の金属酸化物粒子を含む。 The amount of metal oxide particles contained in the raw material of the heat insulating material is not particularly limited as long as the desired characteristics are achieved. The heat insulating material includes, for example, 50 to 100% by weight, 60 to 98% by weight, 70 to 95% by weight, or 80 to 90% by weight of metal oxide particles.
焼結抑制材の量は、例えば、０〜３０重量％、１〜２０重量％、又は２〜１０重量％である。 The amount of the sintering inhibitor is, for example, 0 to 30% by weight, 1 to 20% by weight, or 2 to 10% by weight.
繊維の量は、例えば、０〜２０重量％、１〜１０重量％、又は２〜９重量％である。 The amount of fiber is, for example, 0 to 20% by weight, 1 to 10% by weight, or 2 to 9% by weight.
輻射散乱材の量は、例えば、０〜４０重量％、３〜３５重量％、又は１０〜３０重量％である。 The amount of the radiation scattering material is, for example, 0 to 40% by weight, 3 to 35% by weight, or 10 to 30% by weight.
断熱材の原料は、金属酸化物粒子を、焼結抑制材、繊維及び／又は輻射散乱材を含むときはこれらとの合計を９５重量％以上、９８重量％以上、又は９９重量％以上とすることができる。また、不可避不純物を含んでもよく、１００重量％としてもよい。 When the raw material for the heat insulating material includes the metal oxide particles, including the sintering inhibitor, the fiber, and / or the radiation scattering material, the total amount thereof is 95% by weight or more, 98% by weight or more, or 99% by weight or more. be able to. Moreover, an inevitable impurity may be included and it is good also as 100 weight%.
第１の発明の断熱材は、金属酸化物粒子を、焼結抑制材、繊維及び／又は輻射散乱材を含むときはこれらとの混合物（原料）を成形することにより得られる。より具体的には、例えば、上記の成分を含んで調製された原料を所定の成形型に充填し、乾式プレス成形することにより、当該成形型に対応する形状の乾式加圧成形体を製造する。 The heat insulating material of 1st invention is obtained by shape | molding a mixture (raw material) with these, when a metal oxide particle is included in a sintering suppression material, a fiber, and / or a radiation scattering material. More specifically, for example, a raw material prepared containing the above components is filled in a predetermined mold and dry press molded to produce a dry pressure molded body having a shape corresponding to the mold. .
［第２の発明］
第２の発明の断熱材は、以下の構造を有する。１次粒子である金属酸化物粒子が凝集して、２次粒子を形成し、その内部に１次粒子間でつくる細孔を含む。この２次粒子同士が２次粒子間に細孔を含むように凝集する。金属酸化物粒子は、アルミナ成分を６０重量％以上含む。1次粒子の平均粒径は、１０ｎｍ〜１０００ｎｍである。
[Second invention]
The heat insulating material of the second invention has the following structure. The metal oxide particles that are primary particles aggregate to form secondary particles, which contain pores formed between the primary particles. The secondary particles are aggregated so as to include pores between the secondary particles. The metal oxide particles contain 60% by weight or more of an alumina component. The average particle size of the primary particles is 10 nm to 1000 nm.
金属酸化物粒子は、アルミナ成分を、例えば、８０重量％以上、９０重量％以上、又は９９重量％以上含むことができる。
金属酸化物粒子は、アルミナ成分以外の成分を含むことができる。例えば、アルミナ成分とシリカ成分を含む粒子を用いることができる。例えばアルミナ成分を６０〜８０重量％とシリカ成分を４０〜２０重量％含む金属酸化物粒子を用いることができる。好ましくはアルミナ成分を６５〜７５重量％とシリカ成分を３５〜２５重量％含む金属酸化物粒子を用いることができる。金属酸化物粒子は２種以上混合して用いてもよい。具体的には、例えばアルミナ粒子又はムライト粒子を用いることができる。
The metal oxide particles can contain an alumina component, for example, 80% by weight or more, 90% by weight or more, or 99% by weight or more.
The metal oxide particles can contain components other than the alumina component. For example, particles containing an alumina component and a silica component can be used. For example, metal oxide particles containing 60 to 80% by weight of the alumina component and 40 to 20% by weight of the silica component can be used. Preferably, metal oxide particles containing 65 to 75% by weight of the alumina component and 35 to 25% by weight of the silica component can be used. Two or more kinds of metal oxide particles may be mixed and used. Specifically, for example, alumina particles or mullite particles can be used.
金属酸化物粒子の1次粒子の平均粒径は、好ましくは３０ｎｍ〜６５０ｎｍであり、より好ましくは５０ｎｍ〜５００ｎｍであり、さらに好ましくは７０ｎｍ〜２００ｎｍ、特に好ましくは８０ｎｍ〜１５０ｎｍである。 The average particle size of the primary particles of the metal oxide particles is preferably 30 nm to 650 nm, more preferably 50 nm to 500 nm, still more preferably 70 nm to 200 nm, and particularly preferably 80 nm to 150 nm.
焼成しない状態において、３００ｎｍ以下細孔容積は、好ましくは５％以上である。さらに、３００ｎｍ以下の細孔容積に占める、５０ｎｍ以上３００ｎｍ以下の細孔容積の割合は、好ましくは５０％〜９５％、より好ましくは５５％〜９０％、さらに好ましくは５５％〜８８％、特に好ましくは６０％〜８５％である。 In a state where it is not fired, the pore volume of 300 nm or less is preferably 5% or more. Furthermore, the ratio of the pore volume of 50 nm to 300 nm in the pore volume of 300 nm or less is preferably 50% to 95%, more preferably 55% to 90%, still more preferably 55% to 88%, Preferably, it is 60% to 85%.
２次粒子の平均粒径は、例えば、１００ｎｍ〜１０００ｎｍであり、好ましくは１００ｎｍ〜７００ｎｍより好ましくは１００ｎｍ〜５００ｎｍである。尚、２次粒子の粒径とは、レーザー式粒度分布計で測定した値である。 The average particle size of the secondary particles is, for example, 100 nm to 1000 nm, preferably 100 nm to 700 nm, more preferably 100 nm to 500 nm. The particle size of the secondary particles is a value measured with a laser type particle size distribution meter.
第２の発明の断熱材は、１４００℃で２４時間加熱した後、全ての気孔の容積の合計に対する、径３００ｎｍ以下の気孔の容積の合計の割合は、好ましくは１５％以上、より好ましくは１８％以上、さらに好ましくは２０％以上である。上限は限定されないが、通常５０％以下又は３０％以下である。 In the heat insulating material of the second invention, after heating at 1400 ° C. for 24 hours, the ratio of the total volume of pores having a diameter of 300 nm or less to the total volume of all pores is preferably 15% or more, more preferably 18 % Or more, more preferably 20% or more. Although an upper limit is not limited, Usually, it is 50% or less or 30% or less.
第２の発明の断熱材の加熱前の全ての気孔の容積の合計に対する、径３００ｎｍ以下の気孔の容積の合計の割合は、好ましくは２０％以上、より好ましくは３０％以上、さらに好ましくは４０％以上である。上限は限定されないが、通常７０％以下又は６０％以下である。 The ratio of the total volume of pores having a diameter of 300 nm or less to the total volume of all pores before heating of the heat insulating material of the second invention is preferably 20% or more, more preferably 30% or more, and still more preferably 40 % Or more. Although an upper limit is not limited, Usually, it is 70% or less or 60% or less.
第２の断熱材も、第１の断熱材と同様に、繊維、輻射散乱材、焼結抑制材を含むことができる。その種類や量は、第１の断熱材で説明した通りである。 The 2nd heat insulating material can also contain a fiber, a radiation scattering material, and a sintering suppression material similarly to the 1st heat insulating material. The kind and amount thereof are as described in the first heat insulating material.
第２の発明の断熱材は、以下の製法により製造できる。
平均粒径が１０ｎｍ〜１０００ｎｍの１次粒子である金属酸化物粒子の第１の分散液を作製し、この第１の分散液のｐＨを調整して、１次粒子が凝集した２次粒子の第２の分散液を作製する。第２の分散液を凍結乾燥して２次粒子の凝集体を作製する。得られた凝集体を、プレス成型する。１次粒子、２次粒子の説明は上記と同じである。
The heat insulating material of 2nd invention can be manufactured with the following manufacturing methods.
A first dispersion of metal oxide particles, which are primary particles having an average particle diameter of 10 nm to 1000 nm, is prepared, and the pH of the first dispersion is adjusted to adjust the secondary particles in which the primary particles are aggregated. A second dispersion is prepared. The second dispersion is freeze-dried to produce an aggregate of secondary particles. The obtained aggregate is press-molded. The explanation of the primary particles and the secondary particles is the same as described above.
第１及び第２の断熱材（以下、単に本発明の断熱材ともいう）が取り得る成形体の形状は、特に限られないが、例えば、ボード状、板状又は円筒状である。乾式プレス成形を行う温度は、特に限られないが、例えば、０℃以上、１００℃以下の温度で行うこととしてもよく、０℃以上、５０℃以下の温度で行うこととしてもよい。 The shape of the molded body that can be taken by the first and second heat insulating materials (hereinafter also simply referred to as the heat insulating material of the present invention) is not particularly limited, and is, for example, a board shape, a plate shape, or a cylindrical shape. The temperature at which dry press molding is performed is not particularly limited. For example, the temperature may be 0 ° C. or more and 100 ° C. or less, or may be 0 ° C. or more and 50 ° C. or less.
また、成形体を加熱して強度を出しても構わない。加熱温度は、好ましくは９００℃超１５００℃以下、より好ましくは１０００〜１４００℃である。即ち、成形体は、焼成した後に、断熱材として使用してもよいし、焼成前に断熱材として使用してもよい。 Further, the molded body may be heated to increase the strength. The heating temperature is preferably more than 900 ° C. and not more than 1500 ° C., more preferably 1000 to 1400 ° C. That is, the molded body may be used as a heat insulating material after firing, or may be used as a heat insulating material before firing.
本発明の断熱材は、優れた断熱性を有する。好ましくは、断熱材の１０００℃における熱伝導率は、実施例で測定の方法で、０．１５Ｗ／（ｍ・Ｋ）未満、０．１３Ｗ／（ｍ・Ｋ）以下、又は０．１０Ｗ／（ｍ・Ｋ）以下である。下限は限定されないが、通常０．０５Ｗ／（ｍ・Ｋ）以上である。 The heat insulating material of the present invention has excellent heat insulating properties. Preferably, the heat conductivity of the heat insulating material at 1000 ° C. is less than 0.15 W / (m · K), 0.13 W / (m · K) or less, or 0.10 W / ( m · K) or less. The lower limit is not limited, but is usually 0.05 W / (m · K) or more.
また、密度は、好ましくは０．２０ｇ／ｃｍ３〜１．０ｇ／ｃｍ３であり、より好ましくは０．２５ｇ／ｃｍ３〜０．５０ｇ／ｃｍ３である。 The density is preferably 0.20g / cm 3 ~1.0g / cm 3 , more preferably 0.25g / cm 3 ~0.50g / cm 3 .
本発明の断熱材は、特許文献１のような多孔性であるが、特許文献１の断熱材とは構成が異なる。例えば、特許文献１の断熱材はＭｇＡｌ２Ｏ４等のスピネル成分が必須であるが、本発明の断熱材は主成分（最も重量％の高い成分）としてスピネル成分を含まない。また、本発明の断熱材は発泡体ではない。 Although the heat insulating material of this invention is porous like patent document 1, a structure differs from the heat insulating material of patent document 1. FIG. For example, insulation of Patent Document 1 is spinel component such as MgAl 2 O 4 are essential, the heat insulating material of the present invention do not contain spinel component as the main component (high component of most weight%). Moreover, the heat insulating material of this invention is not a foam.
本発明の断熱体は、エアロゲル、又はエアロゲルと繊維構造体の複合体とは異なる。エアロゲルは通常シリカ同士のシラノール結合を含んだ構造体である。エアロゲルは通常超臨界乾燥で製造する。 The heat insulator of the present invention is different from an airgel or a composite of an airgel and a fiber structure. Airgel is usually a structure containing silanol bonds between silica. Airgel is usually produced by supercritical drying.
本発明の断熱材は、その優れた耐熱性を利用して、高温での耐熱性が要求される環境で使用できる。すなわち、本発明の断熱材は、例えば、１２００℃超又は１４００℃の高温に曝される環境でも使用できる断熱材（例えば、最高使用温度が１２００℃超（例えば、１４００℃）の断熱材）として使用できる。 The heat insulating material of the present invention can be used in an environment where heat resistance at high temperatures is required by utilizing its excellent heat resistance. That is, the heat insulating material of the present invention is, for example, as a heat insulating material that can be used even in an environment exposed to a high temperature of more than 1200 ° C. or 1400 ° C. (for example, a heat insulating material having a maximum use temperature of more than 1200 ° C. (eg, 1400 ° C.)). Can be used.
以下に、本発明の実施例について説明するが、本発明は、これら実施例に限られるものではない。 Examples of the present invention will be described below, but the present invention is not limited to these examples.
＜第１の発明の実施例＞
実施例１
［断熱材の製造］
平均粒径０．２μｍのアルミナ粒子（アルミナ成分９９．９９重量％）と、平均粒径１００ｎｍのジルコニア粒子を、体積比９：１で混合した粒子を、脱気機構が付属した成形型に充填し、乾式プレス成形を行い、その後、成形された板状の乾式加圧成形体を型から取り出し、断熱材を得た。０．５ｇ／ｃｍ３の気孔率は、８７％であった。
<Embodiment of the first invention>
Example 1
[Manufacture of insulation materials]
Filling a mold equipped with a degassing mechanism with a mixture of alumina particles with an average particle size of 0.2 μm (alumina component 99.99% by weight) and zirconia particles with an average particle size of 100 nm in a volume ratio of 9: 1. Then, dry press molding was performed, and then the molded plate-shaped dry pressure-molded body was taken out of the mold to obtain a heat insulating material. The porosity of 0.5 g / cm 3 was 87%.
［断熱材の評価］
以下の方法で断熱材を評価した。結果を表１に示す。
（１）細孔容積割合の測定
得られた断熱材を１４００℃で２４時間で加熱する前と後の細孔容積を、以下の方法で測定した。
[Insulation evaluation]
The heat insulating material was evaluated by the following method. The results are shown in Table 1.
(1) Measurement of pore volume ratio The pore volume before and after heating the obtained heat insulating material at 1400 ° C. for 24 hours was measured by the following method.
Ｍｉｃｒｏｍｅｒｉｔｉｃｓ社製の商品名「ＡｕｔｏＰｏｒｅ ＩＶ ９５００」を用いた。
測定条件：
気孔径範囲：５．５ｎｍ〜３６０μｍ
測定圧力：０．００３６〜２２６．９６ＭＰａ
計算条件：
水銀と試料との接触角：１３０度
水銀の表面張力：４８５ｄｙｎ／ｃｍ
試料に圧力をかけると、試料の気孔に水銀が圧入されていく。圧力と気孔径の関係式から、試料に存在する気孔径とその容量が求まる。断熱材の全気孔体積をＶとする。１４００℃での平均自由行程４００ｎｍに対応した測定圧力以上の細孔量総和をＶ１とし、以下の式で細孔容積割合を算出した。
細孔容積割合（％）＝Ｖ１／Ｖ×１００
The trade name “AutoPore IV 9500” manufactured by Micromeritics was used.
Measurement condition:
Pore diameter range: 5.5 nm to 360 μm
Measurement pressure: 0.0036-226.96 MPa
Calculation condition:
Contact angle between mercury and sample: 130 degrees Surface tension of mercury: 485 dyn / cm
When pressure is applied to the sample, mercury is injected into the pores of the sample. From the relational expression between the pressure and the pore diameter, the pore diameter existing in the sample and its capacity can be obtained. Let V be the total pore volume of the insulation. The pore volume ratio was calculated by the following equation, where V1 was the total pore volume sum above the measurement pressure corresponding to the mean free path of 400 nm at 1400 ° C.
Pore volume ratio (%) = V1 / V × 100
１４００℃で２４時間加熱した後、全ての気孔の容積の合計に対する、径４００ｎｍ以下の気孔の容積の合計の割合を求めた。 After heating at 1400 ° C. for 24 hours, the ratio of the total volume of pores having a diameter of 400 nm or less to the total volume of all pores was determined.
（２）熱伝導率の測定
得られた断熱材について、以下の方法で熱伝導率を測定した。結果を表１に示す。
周期加熱法の概要は以下の文献に示されている。
熱物性２１〔２〕（２００７）８６／９６、「異なる測定方法による断熱材の熱伝導率比較」、大村高弘
周期加熱法により測定した熱拡散率と、投下法による測定した比熱、および試験体の密度の３者を掛け合わせて、熱伝導率を求めた。周期加熱法を簡単に説明すると、試験体の温度の波（周期約１時間、振幅約４Ｋ）を伝播させ、試験体内部における波の時間的遅れ、すなわち位相差から熱拡散率を測定する方法である。具体的には、矩形上の試験体の片面に温度波をかけ、その波が試験体内部を伝播し、試験体の厚さ方向（温度波進行方向）における中央付近で測定された温度波との位相差から、熱拡散率を求めた。また投下法は、高温に加熱した試料を銅（比熱が既知）の容器に落とし、銅容器の温度上昇から比熱を求める方法である。測定温度は１０００℃とした。
(2) Measurement of heat conductivity About the obtained heat insulating material, the heat conductivity was measured with the following method. The results are shown in Table 1.
The outline of the periodic heating method is shown in the following documents.
Thermophysical property 21 [2] (2007) 86/96, “Comparison of thermal conductivity of heat insulating materials by different measuring methods”, Takahiro Omura Thermal diffusivity measured by periodic heating method, specific heat measured by dropping method, and specimen The thermal conductivity was obtained by multiplying the three densities. The periodic heating method will be briefly described. A method of measuring the thermal diffusivity from the time delay of the wave inside the test body, that is, the phase difference, by propagating the temperature wave of the test body (period 1 hour, amplitude 4 K). It is. Specifically, a temperature wave is applied to one side of a rectangular test specimen, the wave propagates inside the specimen, and the temperature wave measured near the center in the thickness direction of the specimen (temperature wave traveling direction) The thermal diffusivity was determined from the phase difference. The dropping method is a method in which a sample heated to a high temperature is dropped into a copper (having a known specific heat) container, and the specific heat is obtained from the temperature rise of the copper container. The measurement temperature was 1000 ° C.
実施例２〜４
表１に示す平均粒径を有するムライト粒子（アルミナ成分６７重量％、シリカ成分３３重量％）を用いた他は、実施例１と同様にして、断熱材を製造し、評価した。結果を表１に示す。
Examples 2-4
A heat insulating material was manufactured and evaluated in the same manner as in Example 1 except that mullite particles having an average particle size shown in Table 1 (alumina component 67 wt%, silica component 33 wt%) were used. The results are shown in Table 1.
比較例１〜３
表１に示す平均粒径を有するアルミナ粒子を用いた他は、実施例１と同様にして、断熱材を製造し、評価した。結果を表１に示す。
Comparative Examples 1-3
A heat insulating material was manufactured and evaluated in the same manner as in Example 1 except that alumina particles having an average particle size shown in Table 1 were used. The results are shown in Table 1.
＜第２の発明の実施例＞
実験例１
１０００℃で熱伝導率が０．１０Ｗ／（ｍ・Ｋ）未満となるためには、３００ｎｍ以下の細孔がどのくらいあればよいかを調べるために以下の実験をした。
様々な粒径のアルミナ微粒子を用いて、３００ｎｍ以下の細孔容積割合が異なる、密度０．５ｇ／ｃｍ３の成形体を製造し、熱伝導率を測定した。結果を図１に示す。この図から、３００ｎｍ以下の細孔容積割合が約１５％以上あれば、熱伝導率が０．１０Ｗ／（ｍ・Ｋ）未満となることが分かる。
<Embodiment of Second Invention>
Experimental example 1
The following experiment was conducted in order to investigate how many pores having a thickness of 300 nm or less are necessary in order that the thermal conductivity at 1000 ° C. is less than 0.10 W / (m · K).
Using alumina fine particles having various particle diameters, molded bodies having a density of 0.5 g / cm 3 having different pore volume ratios of 300 nm or less were produced, and thermal conductivity was measured. The results are shown in FIG. From this figure, it can be seen that when the pore volume ratio of 300 nm or less is about 15% or more, the thermal conductivity is less than 0.10 W / (m · K).
実施例５
（１）断熱材の製造
平均粒子径０．０８μｍのムライト粒子（１次粒子）がｐＨ３〜４の酸性水溶液に分散する分散液を準備した。この分散液のｐＨをアルカリ水を添加してｐＨ７として、１次粒子を凝集させて平均粒子径０．４μｍの２次粒子の分散液を得た。
２次粒子の分散液を、液体窒素の中に入れて凍結乾燥して凝集体を得た。密度は０．０５ｇ／ｃｍ３であった。
Example 5
(1) Production of heat insulating material A dispersion liquid in which mullite particles (primary particles) having an average particle diameter of 0.08 μm are dispersed in an acidic aqueous solution having a pH of 3 to 4 was prepared. The pH of the dispersion was adjusted to pH 7 by adding alkaline water to agglomerate primary particles to obtain a dispersion of secondary particles having an average particle size of 0.4 μm.
The dispersion of secondary particles was placed in liquid nitrogen and freeze-dried to obtain an aggregate. The density was 0.05 g / cm 3 .
上記の製造の工程の模式図を図２に示す。得られた凝集体の写真も併せて示す。得られた凝集体が嵩高いことが分かる。 A schematic diagram of the above manufacturing process is shown in FIG. A photograph of the obtained aggregate is also shown. It turns out that the obtained aggregate is bulky.
上記で得られた凝集体を、脱気機構が付属した成形型に充填し、乾式プレス成形を行い、その後、成形された板状の断熱材（密度０．５ｇ／ｃｍ３）を型から取り出した。 The agglomerates obtained above are filled into a mold equipped with a degassing mechanism, dry press molding is performed, and then the molded plate-shaped heat insulating material (density 0.5 g / cm 3 ) is taken out from the mold. It was.
（２）断熱材の評価１
（１）で得られた乾式加圧成形体を、加熱しないで、ＳＥＭで観察した。３００００倍のＳＥＭ写真を図３に示す。２次粒子内にある細孔（１次粒子間の細孔）と、２次粒子間にある細孔が見られる。
さらに、水銀圧入法により細孔容積割合及び細孔分布を求めた。結果を表２及び図４に示す。図４に示すように、１次粒子由来（２次粒子内）の小さなピークと２次粒子由来（２次粒子間）の大きなピークがあった。
(2) Evaluation 1 of heat insulating material
The dry press-molded body obtained in (1) was observed with an SEM without heating. A SEM photograph at 30000 times is shown in FIG. There are pores in the secondary particles (pores between the primary particles) and pores between the secondary particles.
Furthermore, the pore volume ratio and the pore distribution were determined by mercury porosimetry. The results are shown in Table 2 and FIG. As shown in FIG. 4, there were a small peak derived from the primary particles (within the secondary particles) and a large peak derived from the secondary particles (between the secondary particles).
次に（１）で得られた乾式加圧成形体を、１４００℃で２４時間加熱した。この断熱材について、上記と同様にして細孔容積割合及び細孔分布を測定した。結果を表２及び図５に実線で示す。この図から分かるように、加熱後も、３００ｎｍ以下の細孔が残り、細孔容積割合は１７．６％であった。従って、実験例１からこの断熱材の１０００℃の熱伝導率は０．１０Ｗ／（ｍ・Ｋ）未満といえる。また、全ての細孔（気孔）の容積の合計に対する、径４００ｎｍ以下の気孔の容積の合計の割合は２０％であった。従って、表１からこの断熱材の１０００℃の熱伝導率は０．１０Ｗ／（ｍ・Ｋ）未満といえる。 Next, the dry pressure-molded body obtained in (1) was heated at 1400 ° C. for 24 hours. About this heat insulating material, the pore volume ratio and the pore distribution were measured in the same manner as described above. The results are shown by solid lines in Table 2 and FIG. As can be seen from this figure, pores of 300 nm or less remained after heating, and the pore volume ratio was 17.6%. Therefore, it can be said from Experimental Example 1 that the thermal conductivity of this heat insulating material at 1000 ° C. is less than 0.10 W / (m · K). The ratio of the total volume of pores having a diameter of 400 nm or less to the total volume of all pores (pores) was 20%. Therefore, it can be said from Table 1 that the thermal conductivity of this heat insulating material at 1000 ° C. is less than 0.10 W / (m · K).
（３）断熱材の評価２
（１）で得られた乾式加圧成形体について、１３００℃で２４時間、及び１４００℃で２４時間加熱して、３００ｎｍ以下の細孔の割合を測定した。その結果、１３００℃２４時間加熱後の細孔容積割合は４０％、１４００℃２４時間加熱後の細孔容積割合は１７．６％であった。
(3) Evaluation 2 of heat insulating material
The dry pressure molded body obtained in (1) was heated at 1300 ° C. for 24 hours and 1400 ° C. for 24 hours, and the proportion of pores of 300 nm or less was measured. As a result, the pore volume ratio after heating at 1300 ° C. for 24 hours was 40%, and the pore volume ratio after heating at 1400 ° C. for 24 hours was 17.6%.
実施例６〜８
表２に示す平均粒子径（一次粒子径）のムライト粒子を用いた以外は、実施例５と同様にして乾式加圧成形体を製造して、評価した。結果を表２に示す。
Examples 6-8
A dry pressure molded article was produced and evaluated in the same manner as in Example 5 except that mullite particles having an average particle diameter (primary particle diameter) shown in Table 2 were used. The results are shown in Table 2.
比較例４
（１）断熱材の製造
図２に示すように、実施例５において、２次粒子の分散液を、通常乾燥した他は実施例５と同じようにして、凝集体を得た。
実施例５と同様にして断熱材（密度０．５ｇ／ｃｍ３）を製造した。
Comparative Example 4
(1) Production of heat insulating material As shown in FIG. 2, in Example 5, an aggregate was obtained in the same manner as in Example 5 except that the dispersion of secondary particles was usually dried.
A heat insulating material (density 0.5 g / cm 3 ) was produced in the same manner as in Example 5.
（２）断熱材の評価１
（１）で得られた乾式加圧成形体を、加熱しないでＳＥＭで観察した。その結果、１次粒子間の細孔しか見られず、得られた凝集体は、１次粒子がそのまま集合したものであった。３００００倍のＳＥＭ写真を図６に示す。
実施例５と同様に細孔容積割合及び細孔分布を測定し結果を表２及び図７に示す。この図に示すように、１次粒子由来（１次粒子間）のピークしかなかった。
(2) Evaluation 1 of heat insulating material
The dry pressure molded body obtained in (1) was observed with an SEM without heating. As a result, only pores between the primary particles were observed, and the obtained aggregate was a collection of primary particles as they were. A SEM photograph of 30000 times is shown in FIG.
The pore volume ratio and pore distribution were measured in the same manner as in Example 5, and the results are shown in Table 2 and FIG. As shown in this figure, there was only a peak derived from primary particles (between primary particles).
（１）で得られた乾式加圧成形体を１４００℃で２４時間焼結した断熱材の細孔容積割合及び細孔分布を表２及び図８に実線で示す。この図から分かるように、焼成後は、３００ｎｍ以下の細孔はほとんどなく、細孔容積割合は１．８％であった。従って、実験例１からこの断熱材の熱伝導率は０．１０Ｗ／（ｍ・Ｋ）を超えるといえる。また、全ての細孔（気孔）の容積の合計に対する、径４００ｎｍ以下の気孔の容積の合計の割合は２％であった。 The pore volume ratio and the pore distribution of the heat insulating material obtained by sintering the dry pressure-molded body obtained in (1) at 1400 ° C. for 24 hours are shown by solid lines in Table 2 and FIG. As can be seen from this figure, after firing, there were almost no pores of 300 nm or less, and the pore volume ratio was 1.8%. Therefore, it can be said from Experimental Example 1 that the thermal conductivity of this heat insulating material exceeds 0.10 W / (m · K). The ratio of the total volume of pores having a diameter of 400 nm or less to the total volume of all pores (pores) was 2%.
（３）断熱材の評価２
（１）で得られた乾式加圧成形体について、１３００℃で２４時間、及び１４００℃で２４時間加熱して、３００ｎｍ以下の細孔の割合を測定した。その結果、１３００℃２４時間加熱後の細孔容積割合は１３％、１４００℃２４時間加熱後の細孔容積割合は１．８％であった。
(3) Evaluation 2 of heat insulating material
The dry pressure molded body obtained in (1) was heated at 1300 ° C. for 24 hours and 1400 ° C. for 24 hours, and the proportion of pores of 300 nm or less was measured. As a result, the pore volume ratio after heating at 1300 ° C. for 24 hours was 13%, and the pore volume ratio after heating at 1400 ° C. for 24 hours was 1.8%.
比較例５
表２に示す平均粒子径のムライト粒子を用いた以外は、比較例４と同様にして乾式加圧成形体を製造して、評価した。結果を表２に示す。
Comparative Example 5
A dry pressure-molded article was produced and evaluated in the same manner as in Comparative Example 4 except that mullite particles having an average particle diameter shown in Table 2 were used. The results are shown in Table 2.
Claims (15)
前記２次粒子内と前記２次粒子間に細孔があり、
前記金属酸化物粒子が、アルミナ成分を６０重量％以上含み、前記１次粒子の平均粒径が１０ｎｍ〜１０００ｎｍであり、
１４００℃で２４時間加熱した後、全ての気孔の容積の合計に対する、径４００ｎｍ以下の気孔の容積の合計の割合が、５％以上であり、周期加熱法で測定した１０００℃における熱伝導率が０．１５Ｗ／（ｍ・Ｋ）未満である断熱材。 A heat insulating material composed of secondary particles in which metal oxide particles as primary particles are aggregated,
There are pores in the secondary particles and between the secondary particles,
Wherein the metal oxide particles, the alumina component comprises 60 wt% or more, average particle diameter of the primary particles Ri 10nm~1000nm der,
After heating at 1400 ° C. for 24 hours, the ratio of the total volume of pores having a diameter of 400 nm or less to the total volume of all pores is 5% or more, and the thermal conductivity at 1000 ° C. measured by the periodic heating method is A heat insulating material of less than 0.15 W / (m · K) .
３００ｎｍ以下の細孔容積に占める５０ｎｍ以上３００ｎｍ以下の細孔容積の割合が、５０％〜９５％である請求項１記載の断熱材。 Before firing, the ratio of the total pore volume of 300 nm or less to the total volume of all pores is 5% or more, and the ratio of the pore volume of 50 nm to 300 nm in the pore volume of 300 nm or less is 50% or less. The heat insulating material according to claim 1 , wherein the heat insulating material is in a range of% to 95%.
前記第１の分散液のｐＨを調整して、前記１次粒子が凝集した２次粒子が分散した第２の分散液を作製し、
前記第２の分散液を凍結乾燥して凝集体を作製し、
前記凝集体を、プレス成形する、断熱材の製造方法。 A first dispersion liquid in which metal oxide particles that are primary particles having an average particle diameter of 10 nm to 1000 nm are dispersed is prepared,
Adjusting the pH of the first dispersion to produce a second dispersion in which the secondary particles in which the primary particles are aggregated are dispersed;
The second dispersion is lyophilized to produce an aggregate,
A method for producing a heat insulating material, wherein the aggregate is press-molded.
焼結抑制材を含み、
１４００℃で２４時間加熱した後、全ての気孔の容積の合計に対する、径４００ｎｍ以下の気孔の容積の合計の割合が、５％以上であり、周期加熱法で測定した１０００℃における熱伝導率が０．１５Ｗ／（ｍ・Ｋ）未満である断熱材。 Metal oxide particles having an average particle size of more than 100 nm and containing 60% by weight or more of an alumina component;
Look including a sintering inhibiting material,
After heating at 1400 ° C. for 24 hours, the ratio of the total volume of pores having a diameter of 400 nm or less to the total volume of all pores is 5% or more, and the thermal conductivity at 1000 ° C. measured by the periodic heating method is A heat insulating material of less than 0.15 W / (m · K) .
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