JP4426524B2 - INORGANIC POROUS BODY AND PROCESS FOR PRODUCING THE SAME - Google Patents
INORGANIC POROUS BODY AND PROCESS FOR PRODUCING THE SAME Download PDFInfo
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- JP4426524B2 JP4426524B2 JP2005503540A JP2005503540A JP4426524B2 JP 4426524 B2 JP4426524 B2 JP 4426524B2 JP 2005503540 A JP2005503540 A JP 2005503540A JP 2005503540 A JP2005503540 A JP 2005503540A JP 4426524 B2 JP4426524 B2 JP 4426524B2
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- 238000000034 method Methods 0.000 title claims description 18
- 239000011148 porous material Substances 0.000 claims description 156
- 239000002994 raw material Substances 0.000 claims description 95
- 239000000843 powder Substances 0.000 claims description 94
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 61
- 239000004094 surface-active agent Substances 0.000 claims description 52
- 238000004519 manufacturing process Methods 0.000 claims description 51
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 47
- 239000003002 pH adjusting agent Substances 0.000 claims description 31
- 238000001879 gelation Methods 0.000 claims description 28
- 229910044991 metal oxide Inorganic materials 0.000 claims description 26
- 150000004706 metal oxides Chemical class 0.000 claims description 26
- 229910000000 metal hydroxide Inorganic materials 0.000 claims description 25
- 150000004692 metal hydroxides Chemical class 0.000 claims description 25
- 238000005452 bending Methods 0.000 claims description 24
- 229910010413 TiO 2 Inorganic materials 0.000 claims description 20
- 230000035699 permeability Effects 0.000 claims description 19
- 239000002002 slurry Substances 0.000 claims description 17
- 229910052878 cordierite Inorganic materials 0.000 claims description 16
- JSKIRARMQDRGJZ-UHFFFAOYSA-N dimagnesium dioxido-bis[(1-oxido-3-oxo-2,4,6,8,9-pentaoxa-1,3-disila-5,7-dialuminabicyclo[3.3.1]nonan-7-yl)oxy]silane Chemical compound [Mg++].[Mg++].[O-][Si]([O-])(O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2)O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2 JSKIRARMQDRGJZ-UHFFFAOYSA-N 0.000 claims description 16
- 238000002360 preparation method Methods 0.000 claims description 14
- 229910000505 Al2TiO5 Inorganic materials 0.000 claims description 12
- 229910052751 metal Inorganic materials 0.000 claims description 12
- 239000002184 metal Substances 0.000 claims description 12
- AABBHSMFGKYLKE-SNAWJCMRSA-N propan-2-yl (e)-but-2-enoate Chemical compound C\C=C\C(=O)OC(C)C AABBHSMFGKYLKE-SNAWJCMRSA-N 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
- 229910052839 forsterite Inorganic materials 0.000 claims description 11
- HCWCAKKEBCNQJP-UHFFFAOYSA-N magnesium orthosilicate Chemical compound [Mg+2].[Mg+2].[O-][Si]([O-])([O-])[O-] HCWCAKKEBCNQJP-UHFFFAOYSA-N 0.000 claims description 11
- 239000000203 mixture Substances 0.000 claims description 11
- 229910052863 mullite Inorganic materials 0.000 claims description 11
- 230000032683 aging Effects 0.000 claims description 10
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims description 8
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 7
- 229910004283 SiO 4 Inorganic materials 0.000 claims description 7
- 150000004649 carbonic acid derivatives Chemical class 0.000 claims description 7
- 238000002156 mixing Methods 0.000 claims description 7
- 239000010936 titanium Substances 0.000 claims description 6
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 3
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 3
- 229910052784 alkaline earth metal Inorganic materials 0.000 claims description 3
- 150000001342 alkaline earth metals Chemical class 0.000 claims description 3
- 229910052782 aluminium Inorganic materials 0.000 claims description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 3
- 229910052791 calcium Inorganic materials 0.000 claims description 3
- 239000002131 composite material Substances 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 claims description 3
- 229910052710 silicon Inorganic materials 0.000 claims description 3
- 239000010703 silicon Substances 0.000 claims description 3
- 229910052712 strontium Inorganic materials 0.000 claims description 3
- 229910052719 titanium Inorganic materials 0.000 claims description 3
- 239000003795 chemical substances by application Substances 0.000 claims description 2
- 229910052749 magnesium Inorganic materials 0.000 claims description 2
- 238000010979 pH adjustment Methods 0.000 claims 1
- 239000000499 gel Substances 0.000 description 77
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 58
- 239000007789 gas Substances 0.000 description 30
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 25
- -1 fatty acid salt Chemical class 0.000 description 24
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 19
- 238000001035 drying Methods 0.000 description 16
- 235000019333 sodium laurylsulphate Nutrition 0.000 description 15
- 239000011777 magnesium Substances 0.000 description 14
- 239000012188 paraffin wax Substances 0.000 description 14
- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical compound [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 description 13
- 238000010438 heat treatment Methods 0.000 description 12
- 239000000377 silicon dioxide Substances 0.000 description 12
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 11
- 238000010907 mechanical stirring Methods 0.000 description 10
- 239000012298 atmosphere Substances 0.000 description 8
- 235000014113 dietary fatty acids Nutrition 0.000 description 8
- 239000000194 fatty acid Substances 0.000 description 8
- 229930195729 fatty acid Natural products 0.000 description 8
- 238000003756 stirring Methods 0.000 description 8
- 230000008859 change Effects 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- 238000010304 firing Methods 0.000 description 7
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 6
- 125000000217 alkyl group Chemical group 0.000 description 6
- 235000011114 ammonium hydroxide Nutrition 0.000 description 6
- 239000006260 foam Substances 0.000 description 6
- 238000005187 foaming Methods 0.000 description 6
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 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 5
- 239000012153 distilled water Substances 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 229920000058 polyacrylate Polymers 0.000 description 5
- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 4
- 239000002253 acid Substances 0.000 description 4
- 239000000919 ceramic Substances 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- 230000035939 shock Effects 0.000 description 4
- 238000005245 sintering Methods 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- IAYPIBMASNFSPL-UHFFFAOYSA-N Ethylene oxide Chemical compound C1CO1 IAYPIBMASNFSPL-UHFFFAOYSA-N 0.000 description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 238000012644 addition polymerization Methods 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Natural products N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 3
- 150000003863 ammonium salts Chemical class 0.000 description 3
- 238000001354 calcination Methods 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 239000004088 foaming agent Substances 0.000 description 3
- 229910010272 inorganic material Inorganic materials 0.000 description 3
- 239000011147 inorganic material Substances 0.000 description 3
- 239000002243 precursor Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- FBPFZTCFMRRESA-FSIIMWSLSA-N D-Glucitol Natural products OC[C@H](O)[C@H](O)[C@@H](O)[C@H](O)CO FBPFZTCFMRRESA-FSIIMWSLSA-N 0.000 description 2
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 2
- 239000002202 Polyethylene glycol Substances 0.000 description 2
- 101100422634 Postia placenta (strain ATCC 44394 / Madison 698-R) STS-02 gene Proteins 0.000 description 2
- 229920002125 Sokalan® Polymers 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 230000002776 aggregation Effects 0.000 description 2
- 238000004220 aggregation Methods 0.000 description 2
- 150000005215 alkyl ethers Chemical class 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 2
- 230000008025 crystallization Effects 0.000 description 2
- 150000004665 fatty acids Chemical class 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 239000011810 insulating material Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000011368 organic material Substances 0.000 description 2
- 239000004584 polyacrylic acid Substances 0.000 description 2
- 229920001223 polyethylene glycol Polymers 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 239000000600 sorbitol Substances 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- MXRIRQGCELJRSN-UHFFFAOYSA-N O.O.O.[Al] Chemical compound O.O.O.[Al] MXRIRQGCELJRSN-UHFFFAOYSA-N 0.000 description 1
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 229920001214 Polysorbate 60 Polymers 0.000 description 1
- 229920005830 Polyurethane Foam Polymers 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- 125000000129 anionic group Chemical group 0.000 description 1
- 239000003945 anionic surfactant Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 125000002091 cationic group Chemical group 0.000 description 1
- 239000003093 cationic surfactant Substances 0.000 description 1
- 230000001413 cellular effect Effects 0.000 description 1
- KYKAJFCTULSVSH-UHFFFAOYSA-N chloro(fluoro)methane Chemical compound F[C]Cl KYKAJFCTULSVSH-UHFFFAOYSA-N 0.000 description 1
- 239000008119 colloidal silica Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000005238 degreasing Methods 0.000 description 1
- 238000000280 densification Methods 0.000 description 1
- 230000001687 destabilization Effects 0.000 description 1
- ZBCBWPMODOFKDW-UHFFFAOYSA-N diethanolamine Chemical class OCCNCCO ZBCBWPMODOFKDW-UHFFFAOYSA-N 0.000 description 1
- FPAFDBFIGPHWGO-UHFFFAOYSA-N dioxosilane;oxomagnesium;hydrate Chemical compound O.[Mg]=O.[Mg]=O.[Mg]=O.O=[Si]=O.O=[Si]=O.O=[Si]=O.O=[Si]=O FPAFDBFIGPHWGO-UHFFFAOYSA-N 0.000 description 1
- USIUVYZYUHIAEV-UHFFFAOYSA-N diphenyl ether Natural products C=1C=CC=CC=1OC1=CC=CC=C1 USIUVYZYUHIAEV-UHFFFAOYSA-N 0.000 description 1
- 230000008034 disappearance Effects 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 235000011187 glycerol Nutrition 0.000 description 1
- WQFISPXGYBLULK-UHFFFAOYSA-M heptadecyl-hexadecyl-dimethylazanium;chloride Chemical compound [Cl-].CCCCCCCCCCCCCCCCC[N+](C)(C)CCCCCCCCCCCCCCCC WQFISPXGYBLULK-UHFFFAOYSA-M 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000012770 industrial material Substances 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 235000015110 jellies Nutrition 0.000 description 1
- 239000008274 jelly Substances 0.000 description 1
- 239000000395 magnesium oxide Substances 0.000 description 1
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 1
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 1
- 230000035800 maturation Effects 0.000 description 1
- 150000007522 mineralic acids Chemical class 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 239000002736 nonionic surfactant Substances 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 125000006353 oxyethylene group Chemical group 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 235000021317 phosphate Nutrition 0.000 description 1
- 229920005646 polycarboxylate Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 239000011496 polyurethane foam Substances 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
- C04B38/0051—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof characterised by the pore size, pore shape or kind of porosity
Description
本発明は、無機質多孔体及びその製造方法に関する。さらに詳しくは、連通した気孔からなる気孔構造を有し、ガスを透過させた場合の圧力損失が小さい無機質多孔体、又は独立した気孔からなる気孔構造を有し、熱伝導率が小さい無機質多孔体であって、いずれも熱膨張係数が小さいとともに機械的強度に優れた無機質多孔体、及び気孔構造の大きさや形状の調整が容易で、環境への負荷が小さく、簡易かつ低コストで無機質多孔体の作製が可能な無機質多孔体の製造方法に関する。 The present invention relates to an inorganic porous body and a method for producing the same. More specifically, an inorganic porous body having a pore structure composed of communicating pores and having a small pressure loss when gas is permeated, or an inorganic porous body having a pore structure composed of independent pores and having a low thermal conductivity In both cases, the inorganic porous body has a low thermal expansion coefficient and excellent mechanical strength, and the size and shape of the pore structure can be easily adjusted, the load on the environment is small, and the inorganic porous body is simple and low cost. The present invention relates to a method for producing an inorganic porous body that can be manufactured.
従来、気孔構造（三次元網目構造及び／又はスポンジ状構造）を有する無機質多孔体は、主にアルミナ等の金属酸化物（セラミックス）からなるものが知られている。これらの無機質多孔体は、例えば、下記の方法によって製造されていた。
〔１〕スラリー状のセラミックス原料を、ポリウレタンフォームのようなフォーム状有機物に含浸させ、含浸させたものを乾燥、脱脂及び焼結するとともにフォーム状有機物を焼失させる方法（例えば、特許文献１参照）。
〔２〕アルミナ及び有機バインダーから構成されたスラリーに気泡を導入して気泡含有スラリーを形成し、有機バインダーをゲル化させて保形したものを乾燥、脱脂、及び焼結して無機質多孔体を得る方法（例えば、特許文献２及び特許文献３参照）。
〔３〕コロイダルシリカ、界面活性剤、メタノール及び発泡剤（例えば、フロンガス）からなる混合系を、発泡剤を蒸発（ｖａｐｏｒｉｚａｉｏｎ）させることによって発泡させてからゲル化して無機質多孔体を得る方法（非特許文献１参照）。
〔４〕シリカ前駆体と界面活性剤とを混合するとともに、触媒を混合し、シリカ前駆体と界面活性剤と触媒とを含む水性の原料液を調製する工程と、原料液を発泡し、泡構造を形成する工程と、泡構造を形成した原料液中でのシリカ前駆体の重合により泡構造のまま固定化し、泡構造が維持されたフォーム状の含水シリカを形成する工程と、得られた泡構造が維持されたフォーム状の含水シリカを乾燥する工程とを含む方法（特許文献４参照）。
[1] A method of impregnating a slurry-like ceramic raw material into a foam-like organic material such as polyurethane foam, drying, degreasing and sintering the impregnated material, and burning off the foam-like organic material (for example, see Patent Document 1) .
[2] Bubbles are introduced into a slurry composed of alumina and an organic binder to form a bubble-containing slurry, and the organic binder is gelled and retained, and then dried, degreased, and sintered to form an inorganic porous body. A method of obtaining (see, for example, Patent Document 2 and Patent Document 3).
[3] A method for obtaining an inorganic porous material by foaming a mixed system composed of colloidal silica, a surfactant, methanol and a foaming agent (for example, Freon gas) by evaporating the foaming agent and then gelling the mixture Patent Document 1).
[4] A step of mixing a silica precursor and a surfactant and mixing a catalyst to prepare an aqueous raw material liquid containing the silica precursor, the surfactant, and the catalyst; A step of forming a structure, a step of forming a foamed hydrous silica in which the foam structure is maintained by fixing the foam structure by polymerization of the silica precursor in the raw material liquid in which the foam structure is formed, and obtained. Drying the foam-like hydrous silica having a maintained foam structure (see Patent Document 4).
しかしながら、これらの従来の無機質多孔体（セラミックス発泡体）はそれぞれ下記のような問題を有していた。すなわち、〔１〕及び〔２〕の方法は、脱脂が困難であるという問題があるとともに、有機物の焼失に伴い炭酸ガスを放出することになり、環境保護の面で問題があった。また、〔３〕の方法は、発泡剤としてフロンガス等が用いられるため、オゾン層破壊などの環境保護の面で問題があった。さらに、〔４〕の方法は、用いる原材料が高価であるという問題があった。 However, these conventional inorganic porous bodies (ceramic foams) have the following problems. That is, the methods [1] and [2] have a problem that it is difficult to degrease, and carbon dioxide gas is released when the organic substance is burned out, which causes a problem in terms of environmental protection. Further, the method [3] has a problem in terms of environmental protection such as destruction of the ozone layer because chlorofluorocarbon is used as a foaming agent. Furthermore, the method [4] has a problem that the raw materials used are expensive.
本発明の無機質多孔体及びその製造方法は、上述の問題に鑑みてなされたものであり、連通した気孔からなる気孔構造を有し、ガスを透過させた場合の圧力損失が小さい無機質多孔体、又は独立した気孔からなる気孔構造を有し、熱伝導率が小さい無機質多孔体であって、いずれも熱膨張係数が小さいとともに機械的強度に優れた無機質多孔体、及び気孔構造の大きさや形状の調整が容易で、環境への負荷が小さく、簡易かつ低コストで無機質多孔体の作製が可能な無機質多孔体の製造方法を提供することを目的とする。
本発明は上記の目的を達成するためになされたものであり、本発明によって、以下の無機質多孔体及びその製造方法が提供される。
［１］少なくともその一部が球状である多数の連通した気孔からなる気孔構造（三次元網目構造及び／又はスポンジ状構造）を有する無機質多孔体であって、前記気孔構造を形成する前記気孔の大きさが、５μｍ〜２ｍｍであり、気孔率が６０％以上であり、かつガス透過係数が１×１０−１１ｍ２以上であることを特徴とする無機質多孔体（以下、「第１の無機質多孔体」ということがある）。
［２］シリカ（ＳｉＯ２）、チタニア（ＴｉＯ２）、コージェライト（Ｍｇ２Ａｌ４Ｓｉ５Ｏ１８）、ムライト（３Ａｌ２Ｏ３・２ＳｉＯ２）、フォルステライト（Ｍｇ２ＳｉＯ４）及びアルミニウムチタネート（Ａｌ２ＴｉＯ５）からなる群から選ばれる少なくとも一種を主成分とする前記［１］に記載の無機質多孔体。
［３］少なくともその一部が球状である多数の独立した気孔からなる気孔構造（スポンジ状構造）を有する無機質多孔体であって、前記気孔構造を形成する前記気孔の大きさが、５μｍ〜２ｍｍであり、気孔率が６０％以上であり、前記気孔構造を形成する前記気孔のうち、球状の前記気孔の占める割合（（球状の気孔の容積／全ての気孔の容積）×１００）が、６０％以上であり、熱伝導率が０．０７Ｗ／ｍＫ以下であることを特徴とする無機質多孔体（以下、「第２の無機質多孔体」ということがある）。
［４］シリカ（ＳｉＯ２）、チタニア（ＴｉＯ２）、コージェライト（Ｍｇ２Ａｌ４Ｓｉ５Ｏ１８）、ムライト（３Ａｌ２Ｏ３・２ＳｉＯ２）、フォルステライト（Ｍｇ２ＳｉＯ４）及びアルミニウムチタネート（Ａｌ２ＴｉＯ５）からなる群から選ばれる少なくとも一種を主成分とする前記［３］に記載の無機質多孔体。
［５］シリカ（ＳｉＯ２）を主成分とし、熱膨張係数が２×１０−６Ｋ−１以下で、曲げ強度が１ＭＰａ以上である前記［１］〜［４］のいずれかに記載の無機質多孔体。
［６］コージェライト（Ｍｇ２Ａｌ４Ｓｉ５Ｏ１８）を主成分とし、熱膨張係数が２．２×１０−６Ｋ−１以下で、曲げ強度が０．５ＭＰａ以上である前記［１］〜［４］のいずれかに記載の無機質多孔体。
［７］金属酸化物ゾル及び／又は金属水酸化物ゾルと、第１の界面活性剤と、第１のｐＨ調整剤とを、その粘度が１００〜２００００ｍＰａ・ｓとなるようなｐＨと温度との条件で混合して、所定のゲル化時間を有する原料ゾルを調製し、得られた前記原料ゾルを機械的に攪拌して、気泡が導入されたゾル多孔体を形成し、得られた前記ゾル多孔体を、必要に応じ所定温度で加熱して、ゲル化させ、ゲル多孔体を形成し、得られた前記ゲル多孔体を乾燥して、乾燥ゲル多孔体を形成し、得られた前記乾燥ゲル多孔体を熱処理することを特徴とする無機質多孔体の製造方法（以下、「第１の製造方法」ということがある）。
［８］前記ゲル多孔体を乾燥して、前記乾燥ゲル多孔体を形成し、得られた前記乾燥ゲル多孔体を熱処理する際に、前記ゲル多孔体を、温度と湿度を保持したまま静置して熟成して、熟成ゲル多孔体を形成し、得られた前記熟成ゲル多孔体を、温度を保持したまま、湿度を下げて予備乾燥して、予備乾燥ゲル多孔体を形成し、前記予備乾燥ゲル多孔体を乾燥して、前記乾燥ゲル多孔体を形成し、得られた前記乾燥ゲル多孔体を熱処理する前記［７］に記載の無機質多孔体の製造方法。
［９］前記ゲル多孔体を熱処理した後に、さらに焼成する前記［７］又は［８］に記載の無機質多孔体の製造方法。
［１０］前記金属酸化物ゾル及び／又は金属水酸化物ゾルが、シリカ（ＳｉＯ２）ゾル及び／又はチタニア（ＴｉＯ２）ゾルである前記［７］〜［９］のいずれかに記載の無機質多孔体の製造方法。
［１１］一方で、金属酸化物ゾル及び／又は金属水酸化物ゾルと、第２の界面活性剤と、第２のｐＨ調整剤とを、その粘度が１００〜２００００ｍＰａ・ｓとなるようなｐＨと温度との条件で混合して、所定のゲル化時間を有する原料ゾルを調製し、他方で、金属酸化物、金属水酸化物及び金属炭酸塩からなる群から選ばれる少なくとも一種の原料粉末を含む原料粉末調製物を調製し、得られた前記原料ゾルと前記原料粉末調製物とを混合し、次いで、機械的に攪拌して、気泡が導入された粉末含有ゾル多孔体を形成し、得られた前記粉末含有ゾル多孔体を、必要に応じ所定温度で加熱して、ゲル化させ、粉末含有ゲル多孔体を形成し、得られた前記粉末含有ゲル多孔体を乾燥して、乾燥粉末含有ゲル多孔体を形成し、得られた前記乾燥粉末含有ゲル多孔体を熱処理することを特徴とする無機質多孔体の製造方法（以下、「第２の製造方法」ということがある）。
［１２］前記原料粉末調製物が、金属酸化物、金属水酸化物及び金属炭酸塩からなる群から選ばれる少なくとも一種の前記原料粉末を含む粉末スラリーと、第３の界面活性剤と、第３のｐＨ調整剤とを、前記原料粉末の濃度が１重量％以上で、かつ前記原料ゾルと同じｐＨとなるような条件で混合して調製された、原料スラリーである前記［１１］に記載の無機質多孔体の製造方法。
［１３］前記粉末含有ゲル多孔体を乾燥して、前記乾燥粉末含有ゲル多孔体を形成し、得られた前記乾燥粉末含有ゲル多孔体を熱処理する際に、前記粉末含有ゲル多孔体を、温度及び湿度を保持したまま静置して熟成して、熟成粉末含有ゲル多孔体を形成し、得られた前記熟成粉末含有ゲル多孔体を、温度を保持したまま、湿度を下げて予備乾燥して、予備乾燥粉末含有ゲル多孔体を形成し、前記予備乾燥粉末含有ゲル多孔体を乾燥して、前記乾燥粉末含有ゲル多孔体を形成し、得られた前記乾燥粉末含有ゲル多孔体を熱処理する前記［１１］又は［１２］に記載の無機質多孔体の製造方法。
［１４］前記粉末含有ゲル多孔体を熱処理した後に、さらに焼成する前記［１１］〜［１３］のいずれかに記載の無機質多孔体の製造方法。
［１５］前記金属酸化物ゾル及び／又は金属水酸化物ゾルが、シリカ（ＳｉＯ２）ゾル及び／又はチタニア（ＴｉＯ２）ゾルであり、かつ前記金属酸化物、金属水酸化物及び金属炭酸塩からなる群から選ばれる少なくとも一種の原料粉末が、ケイ素（Ｓｉ）、チタン（Ｔｉ）、アルミニウム（Ａｌ）及びアルカリ土類金属（Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｒａ）からなる群から選ばれる少なくとも一の元素の酸化物、水酸化物、炭酸塩及び／又はこれらの複合酸化物の粉末である前記［１１］〜［１４］のいずれかに記載の無機質多孔体の製造方法。
本発明によって、連通した気孔からなる気孔構造を有し、ガスを透過させた場合の圧力損失が小さい無機質多孔体、又は独立した気孔からなる気孔構造を有し、熱伝導率が小さい無機質多孔体であって、いずれも熱膨張係数が小さいとともに機械的強度に優れた無機質多孔体、及び気孔構造の大きさや形状の調整が容易で、環境への負荷が小さく、簡易かつ低コストで無機質多孔体の作製が可能な無機質多孔体の製造方法が提供される。The inorganic porous body and the method for producing the same of the present invention have been made in view of the above-mentioned problems, have a pore structure composed of continuous pores, and have a small pressure loss when gas is permeated, Or an inorganic porous body having a pore structure composed of independent pores and low thermal conductivity, both of which have a low thermal expansion coefficient and excellent mechanical strength, and the size and shape of the pore structure An object of the present invention is to provide a method for producing an inorganic porous material that is easy to adjust, has a low environmental impact, and can be produced simply and at low cost.
This invention is made | formed in order to achieve said objective, The following inorganic porous bodies and its manufacturing method are provided by this invention.
[1] An inorganic porous body having a pore structure (three-dimensional network structure and / or sponge-like structure) composed of a large number of continuous pores, at least a part of which is spherical, and the pores forming the pore structure An inorganic porous material (hereinafter referred to as “first inorganic material”) having a size of 5 μm to 2 mm, a porosity of 60% or more, and a gas permeability coefficient of 1 × 10 −11 m 2 or more. Sometimes referred to as a porous body).
[2] Silica (SiO 2 ), titania (TiO 2 ), cordierite (Mg 2 Al 4 Si 5 O 18 ), mullite (3Al 2 O 3 · 2SiO 2 ), forsterite (Mg 2 SiO 4 ) and aluminum titanate The inorganic porous material according to [1], wherein at least one selected from the group consisting of (Al 2 TiO 5 ) is a main component.
[3] An inorganic porous body having a pore structure (sponge-like structure) composed of a large number of independent pores, at least a part of which is spherical, and the pore size forming the pore structure is 5 μm to 2 mm And the ratio of the spherical pores among the pores forming the pore structure ((volume of spherical pores / volume of all pores) × 100) is 60 % Of an inorganic porous body having a thermal conductivity of 0.07 W / mK or less (hereinafter sometimes referred to as “second inorganic porous body”).
[4] Silica (SiO 2 ), titania (TiO 2 ), cordierite (Mg 2 Al 4 Si 5 O 18 ), mullite (3Al 2 O 3 · 2SiO 2 ), forsterite (Mg 2 SiO 4 ) and aluminum titanate The inorganic porous material according to [3], wherein at least one selected from the group consisting of (Al 2 TiO 5 ) is a main component.
[5] The inorganic material according to any one of [1] to [4], including silica (SiO 2 ) as a main component, a thermal expansion coefficient of 2 × 10 −6 K −1 or less, and a bending strength of 1 MPa or more. Porous body.
[6] The above [1] having cordierite (Mg 2 Al 4 Si 5 O 18 ) as a main component, a thermal expansion coefficient of 2.2 × 10 −6 K −1 or less, and a bending strength of 0.5 MPa or more. -The inorganic porous body in any one of [4].
[7] A pH and temperature at which the viscosity of the metal oxide sol and / or metal hydroxide sol, the first surfactant, and the first pH adjuster is 100 to 20000 mPa · s. To prepare a raw material sol having a predetermined gelation time, mechanically stirring the obtained raw material sol, forming a sol porous body into which bubbles are introduced, and obtaining the obtained sol The sol porous body is heated at a predetermined temperature as necessary to be gelled to form a gel porous body, and the obtained gel porous body is dried to form a dry gel porous body, and the obtained A method for producing an inorganic porous material, characterized by heat-treating the dried gel porous material (hereinafter sometimes referred to as “first production method”).
[8] The gel porous body is dried to form the dry gel porous body, and when the obtained dried gel porous body is heat-treated, the gel porous body is allowed to stand while maintaining temperature and humidity. Aged gel porous body is formed, and the obtained aged gel porous body is preliminarily dried at a reduced humidity while maintaining the temperature to form a preliminarily dried gel porous body. The method for producing an inorganic porous body according to [7], wherein the dried gel porous body is dried to form the dried gel porous body, and the obtained dried gel porous body is heat-treated.
[9] The method for producing an inorganic porous material according to [7] or [8], wherein the gel porous material is further baked after being heat-treated.
[10] The inorganic material according to any one of [7] to [9], wherein the metal oxide sol and / or metal hydroxide sol is a silica (SiO 2 ) sol and / or a titania (TiO 2 ) sol. A method for producing a porous body.
[11] On the other hand, the pH at which the viscosity of the metal oxide sol and / or metal hydroxide sol, the second surfactant, and the second pH adjuster is 100 to 20000 mPa · s. And at least one raw material powder selected from the group consisting of metal oxides, metal hydroxides, and metal carbonates. The raw material powder preparation is prepared, the obtained raw material sol and the raw material powder preparation are mixed, and then mechanically stirred to form a powder-containing sol porous body into which bubbles are introduced. The obtained powder-containing sol porous body is heated at a predetermined temperature as necessary to be gelled to form a powder-containing gel porous body, and the obtained powder-containing gel porous body is dried to contain a dry powder. The dry powder obtained by forming a gel porous body Manufacturing method for the inorganic porous body, characterized in that heat treatment of organic gel porous body (hereinafter sometimes referred to as "second production method").
[12] A powder slurry containing at least one kind of the raw material powder selected from the group consisting of a metal oxide, a metal hydroxide and a metal carbonate, a third surfactant, and a third surfactant. The raw material slurry according to [11], wherein the raw material slurry is prepared by mixing the raw material powder under a condition such that the concentration of the raw material powder is 1% by weight or more and has the same pH as the raw material sol. A method for producing an inorganic porous material.
[13] When the powder-containing gel porous body is dried to form the dry powder-containing gel porous body and the obtained dry powder-containing gel porous body is heat-treated, And the aging powder-containing gel porous body is formed by standing still while maintaining the humidity, and the obtained aging powder-containing gel porous body is preliminarily dried by decreasing the humidity while maintaining the temperature. Forming the preliminary dry powder-containing gel porous body, drying the preliminary dry powder-containing gel porous body, forming the dry powder-containing gel porous body, and heat-treating the obtained dry powder-containing gel porous body [11] The method for producing an inorganic porous material according to [12].
[14] The method for producing an inorganic porous material according to any one of [11] to [13], wherein the powder-containing gel porous material is heat-treated and then further baked.
[15] The metal oxide sol and / or metal hydroxide sol is a silica (SiO 2 ) sol and / or titania (TiO 2 ) sol, and the metal oxide, metal hydroxide and metal carbonate At least one raw material powder selected from the group consisting of: at least selected from the group consisting of silicon (Si), titanium (Ti), aluminum (Al), and alkaline earth metals (Mg, Ca, Sr, Ba, Ra) The method for producing an inorganic porous body according to any one of the above [11] to [14], which is a powder of one element oxide, hydroxide, carbonate and / or a composite oxide thereof.
According to the present invention, an inorganic porous body having a pore structure composed of continuous pores and having a small pressure loss when gas is permeated, or an inorganic porous body having a pore structure composed of independent pores and having a low thermal conductivity In both cases, the inorganic porous body has a low thermal expansion coefficient and excellent mechanical strength, and the size and shape of the pore structure can be easily adjusted, the load on the environment is small, and the inorganic porous body is simple and low cost. The manufacturing method of the inorganic porous body which can produce is provided.
図１は、本発明の実施例１で得られたシリカ質多孔体の気孔構造を走査型電子顕微鏡で観察した結果を示す写真である。
図２は、本発明の実施例２で得られたシリカ質多孔体の気孔構造を走査型電子顕微鏡で観察した結果を示す写真である。
図３は、本発明の実施例３で得られたシリカ質多孔体の気孔構造を走査型電子顕微鏡で観察した結果を示す写真である。
図４は、本発明の実施例４で得られたシリカ質多孔体の気孔構造を走査型電子顕微鏡で観察した結果を示す写真である。
図５は、本発明の実施例５で得られたシリカ質多孔体の気孔構造を走査型電子顕微鏡で観察した結果を示す写真である。
図６は、本発明の実施例６で得られたチタニア質多孔体の気孔構造を走査型電子顕微鏡で観察した結果を示す写真である。
図７は、本発明の実施例７で得られたシリカ質多孔体の気孔構造を走査型電子顕微鏡で観察した結果を示す写真である。
図８は、本発明の実施例９で得られたコージェライト質多孔体の気孔構造を走査型電子顕微鏡で観察した結果を示す写真である。
図９は、本発明の比較例１で得られたシリカ質多孔体の気孔構造を走査型電子顕微鏡で観察した結果を示す写真である。FIG. 1 is a photograph showing the result of observing the pore structure of the siliceous porous material obtained in Example 1 of the present invention with a scanning electron microscope.
FIG. 2 is a photograph showing the result of observation of the pore structure of the siliceous porous material obtained in Example 2 of the present invention with a scanning electron microscope.
FIG. 3 is a photograph showing the result of observing the pore structure of the siliceous porous material obtained in Example 3 of the present invention with a scanning electron microscope.
FIG. 4 is a photograph showing the result of observation of the pore structure of the siliceous porous material obtained in Example 4 of the present invention with a scanning electron microscope.
FIG. 5 is a photograph showing the result of observing the pore structure of the siliceous porous material obtained in Example 5 of the present invention with a scanning electron microscope.
FIG. 6 is a photograph showing the results of observation of the pore structure of the titania porous material obtained in Example 6 of the present invention with a scanning electron microscope.
FIG. 7 is a photograph showing the result of observation of the pore structure of the siliceous porous material obtained in Example 7 of the present invention with a scanning electron microscope.
FIG. 8 is a photograph showing the result of observation of the pore structure of the cordierite porous material obtained in Example 9 of the present invention with a scanning electron microscope.
FIG. 9 is a photograph showing the result of observation of the pore structure of the siliceous porous material obtained in Comparative Example 1 of the present invention with a scanning electron microscope.
本発明の無機質多孔体は、少なくともその一部が球状である多数の気孔からなる気孔構造（三次元網目構造及び／又はスポンジ状構造）を有する無機質多孔体であって、気孔構造を形成する気孔の大きさが、５μｍ〜２ｍｍであり、気孔率が６０％以上のものである。
本発明の第１の無機質多孔体を構成する主成分としては特に制限はないが、シリカ（ＳｉＯ２）、チタニア（ＴｉＯ２）、コージェライト（Ｍｇ２Ａｌ４Ｓｉ５Ｏ１８）、ムライト（３Ａｌ２Ｏ３・２ＳｉＯ２）、フォルステライト（Ｍｇ２ＳｉＯ４）及びアルミニウムチタネート（Ａｌ２ＴｉＯ５）からなる群から選ばれる少なくとも一種が好ましく、第２の無機質多孔体を構成する主成分としては、シリカ（ＳｉＯ２）、チタニア（ＴｉＯ２）、コージェライト（Ｍｇ２Ａｌ４Ｓｉ５Ｏ１８）、ムライト（３Ａｌ２Ｏ３・２ＳｉＯ２）、フォルステライト（Ｍｇ２ＳｉＯ４）及びアルミニウムチタネート（Ａｌ２ＴｉＯ５）からなる群から選ばれる少なくとも一種が好ましい。シリカ（ＳｉＯ２）、チタニア（ＴｉＯ２）、コージェライト（Ｍｇ２Ａｌ４Ｓｉ５Ｏ１８）、ムライト（３Ａｌ２Ｏ３・２ＳｉＯ２）、フォルステライト（Ｍｇ２ＳｉＯ４）、アルミニウムチタネート（Ａｌ２ＴｉＯ５）としても特に制限はないが、結晶相として多形のあるものについては、熱膨張特性や、触媒特性の観点から、シリカ（ＳｉＯ２）の場合には、アモルファス（非晶質）のもの、チタニア（ＴｉＯ２）の場合には、アナターゼ型、アルミニウムチタネート（Ａｌ２ＴｉＯ５）の場合には、低温型（β相）、を好適例として挙げることができる。なお、本発明においては、コージェライト（Ｍｇ２Ａｌ４Ｓｉ５Ｏ１８）として、その多形（化学組成は同じだが結晶構造が異なるもの）であるインディアライトも含む。これらは一種単独であってもよく、二種以上を混合したものであってもよい。
本発明の第１の無機質多孔体は、少なくともその一部が球状である多数の連通した気孔からなる気孔構造（三次元網目構造及び／又はスポンジ状構造）を有する。この気孔の大きさは、５μｍ〜２ｍｍであることが必要である。５μｍ未満であるとガス透過係数が小さくなり（ガスを透過させた場合、圧力損失が高くなり）、２ｍｍを超えると、強度が小さくなる。また、本発明の第１の無機質多孔体は、気孔率が６０％以上であることが必要である。気孔率が６０％未満であると、ガス透過係数が小さくなる（ガスを透過させた場合、圧力損失が高くなる）。ガス透過係数は１×１０−１１ｍ２以上であることが必要である。
本発明の第２の無機質多孔体は、少なくともその一部が球状である多数の独立した気孔からなる気孔構造（スポンジ状構造）を有する。この気孔の大きさは、５μｍ〜２ｍｍであることが必要である。５μｍ未満であっても特性に問題はないが、泡を安定化させるための界面活性剤の使用量が多くなり、環境への負荷が高くなり、２ｍｍを超えると、機械的強度が小さくなる。また、気孔率が６０％以上であることが必要なのは、第１の無機質多孔体の場合と同様である。また、気孔構造を形成する気孔のうち、球状の気孔の占める割合（（球状の気孔の容積／全ての気孔の容積）×１００）が、６０％以上であることが必要である。６０％未満であると、熱伝導率が高くなる。また、熱伝導率は０．０７Ｗ／ｍＫ以下であることが必要である。
また、本発明の第１の無機質多孔体及び第２の無機質多孔体は、シリカを主成分とし、その熱膨張係数が２×１０−６Ｋ−１以下、曲げ強度が１ＭＰａ以上であることが好ましい。熱膨張係数が、２×１０−６Ｋ−１を超えると、耐熱衝撃性に問題を生じることがある。また、曲げ強度が１ＭＰａ未満であると、構造材料として使用することができなかったり、耐熱衝撃性に問題を生じることがある。
また、本発明の第１の無機質多孔体及び第２の無機質多孔体は、コージェライト（Ｍｇ２Ａｌ４Ｓｉ５Ｏ１８）を主成分とし、熱膨張係数が２．２×１０−６Ｋ−１以下で、曲げ強度が０．５ＭＰａ以上であることが好ましい。熱膨張係数が、２．２×１０−６Ｋ−１を超えると、耐熱衝撃性に問題を生じることがある。また、曲げ強度が０．５ＭＰａ未満であると、構造材料として使用することができなかったり、耐熱衝撃性に問題を生じることがある。
本発明の第１の無機質多孔体は、熱膨張係数が小さく、曲げ強度に優れる上に、ガス透過係数が１×１０−１１ｍ２以上と大きく、ガスを透過させた場合、圧力損失を低下させることが可能なため、フィルター等の用途に好適に用いられる。
本発明の第２の無機質多孔体は、熱膨張係数が小さく、曲げ強度に優れる上に、熱伝導率が０．０７Ｗ／ｍＫ以下と小さく、断熱性に優れるため、断熱材等の用途に好適に用いられる。
本発明の無機質多孔体の製造方法（第１の製造方法）は、金属酸化物ゾル及び／又は金属水酸化物ゾルと、第１の界面活性剤と、第１のｐＨ調整剤とを、その粘度が１００〜２００００ｍＰａ・ｓとなるようなｐＨと温度との条件で混合して、所定のゲル化時間を有する原料ゾルを調製し、得られた前記原料ゾルを機械的に攪拌して、気泡が導入されたゾル多孔体を形成し、得られた前記ゾル多孔体を所定温度で加熱してゲル化させ、ゲル多孔体を形成し、得られた前記ゲル多孔体を乾燥して、乾燥ゲル多孔体を形成し、得られた前記乾燥ゲル多孔体を熱処理することを特徴とする。
第１の製造方法においては、まず、金属酸化物ゾル及び／又は金属水酸化物ゾル（好適例として、シリカ（ＳｉＯ２）ゾル、チタニア（ＴｉＯ２）ゾルを挙げることができる）と、第１の界面活性剤と、第１のｐＨ調整剤とを、その粘度が１００〜２００００ｍＰａ・ｓとなるようなｐＨと温度との条件で混合して、所定のゲル化時間を有する原料ゾルを調製する。
以下、金属酸化物ゾル及び／又は金属水酸化物ゾルとして、シリカ（ＳｉＯ２）ゾル及び／又はチタニア（ＴｉＯ２）ゾルを用いた場合について説明する。
通常、シリカ（ＳｉＯ２）ゾル及び／又はチタニア（ＴｉＯ２）ゾルは、溶媒（水）にゾル粒子（シリカ又はチタニアの数ｎｍ〜数十ｎｍの粒子）が単分散しており、その状態で各種用途に用いられることが多く、そのため、単分散の状態が安定して長時間保てるような工夫がされている。この状態が不安定になると、粒子どうしが凝集し、その凝集がゾル全体に行き渡って、その結果ゲル化することになる（全体がゼリー状に固化して、粘度が極端に高い状態になる）。このゲル化までの粘度の変化は、数ヶ月〜数年のオーダーで徐々に高まっていくが、それを数分〜数時間のオーダーとなるように強制的に早めてやる（所定時間で原料ゾルがゲル化するように制御する）のが第１の製造方法の一つの特徴である。
一般に、ゾルをゲル化させる駆動力は、ゾルの凝集が生じ易い状態を作り出すことによって得ることができる。すなわち、〔１〕ｐＨ調整による表面電位の低下、〔２〕温度上昇によるゾル粒子同士の衝突頻度の上昇、〔３〕濃度上昇によるゾル粒子同士の衝突頻度の上昇、〔４〕電解質添加による表面電位状態の不安定化等によって、ゾルは凝集し易くなり、ゲル化が促進される。第１の製造方法においては、第１のｐＨ調整剤の添加が、〔１〕（場合によっては〔４〕も）の作用によるゲル化の促進に、また、加熱が、〔２〕の作用によるゲル化の促進にそれぞれ対応している。
このように、原料ゾルの粘度の時間変化を強制的に早める（所定時間で原料ゾルがゲル化するように制御する）方法として、ｐＨと温度とを制御することによる方法を第１の製造方法では利用している。通常のシリカゾルではｐＨ＝１０程度（チタニアゾルはｐＨ＝１程度）であるが、原料ゾルのｐＨを５〜７（チタニアゾルはｐＨ＝２〜４）に制御することで、ゲル化（粘度が数万ｍＰａ・ｓとなる）時間は数分〜数時間となる。また、温度を高くするとゲル化時間は早まることになる（ゲル化時間は温度に対して反比例的に減少する）。例えば、シリカゾルをｐＨ＝６とした場合、温度が２０℃ではゲル化時間が４０〜６０分程度であるが、４０℃の場合にはその４分の１程度の１０〜３０分程度となる。また、２０℃でゲル化を進行させておいて、４０℃に加熱することによって急激にゲル化させることもできる。
上述の方法によって制御されるゲル化時間は、通常、１分から１時間が好ましく、作業のしやすさの観点からすると、数分から数十分がさらに好ましい。また、原料ゾルに気泡を導入して気孔を形成した後に温度を変化させてもよい。このようにすることによって、気孔構造を、形成時の状態に保持したまま瞬時にゲル化させることができ、気孔構造を構成する気孔の形状、大きさを容易に制御することが可能となる。
上記のようにゲル化時間の制御（粘度の時間変化の制御）をすることで、後述する気泡を導入する際の粘度を１００〜２００００ｍＰａ・ｓの範囲で任意に選ぶことができる。すなわち、所定の組成でゾルを調製した後、一定温度（例えば、２０℃）でそのゾルの粘度の変化を測定することが好ましい。
このように、第１の製造方法においては、後述する気泡を導入する際の原料ゾルの粘度を１００〜２００００ｍＰａ・ｓの範囲に調整することが重要であり、ｐＨと温度とは、原料ゾルの粘度をこのような範囲にすることができるものであれば、適宜、組み合わせることができる。
ここで、第１の製造方法に用いられるシリカ（ＳｉＯ２）ゾル及び／又はチタニア（ＴｉＯ２）ゾルとしては、所定の条件でゲル化するものであれば特に制限はないが、例えば、平均粒径が１０ｎｍ、濃度が３０％のものを好適例として挙げることができる。シリカ（ＳｉＯ２）ゾル及びチタニア（ＴｉＯ２）ゾルのうちいずれか一種単独で用いてもよく、二種を混合したものを用いてもよい。シリカ（ＳｉＯ２）ゾル及びチタニア（ＴｉＯ２）ゾルの濃度は、市販されているどのような濃度であってもよいが、薄すぎるとゲル化後の機械的強度が弱く、形状を保つことが困難であるので２０％以上が好ましい。
第１の製造方法に用いられる第１の界面活性剤としては、起泡性に富むものであり、得られる原料ゾルに気泡を導入することによって安定した気孔を形成することができるものであれば、陰イオン性、陽イオン性、非イオン性、両イオン性のいずれであってもよいが、直鎖型の界面活性剤が好ましい。また、ｐＨに影響を与えない非イオン性のものが好ましい。さらに、仮焼後に不純物が残らないようにアルカリ金属等が含まれないものが好ましい。具体的には、陰イオン性界面活性剤として、脂肪酸塩、アルキル硫酸エステル塩、ポリオキシエチレンアルキルエーテル硫酸エステル塩、アルキルベンゼンスルフォン酸塩、アルキルナフタレンスルフォン酸塩、アルキルスルホコハク酸塩、アルキルジフェニルエーテルジスルフォン酸塩、アルキルリン酸塩、ポリカルボン酸塩を挙げることができる。また、陽イオン性界面活性剤として、塩化ヘキサデシルセチルトリメチルアンモニウム等の高級アルキル基と低級アルキル基とを有する脂肪族四級アンモニウム塩、高級アルキル基と低級アルキル基とを有する脂肪族アミン塩等を挙げることができる。また、非イオン性界面活性剤として、高級アルキル基とオキシエチレン基とを有するポリオキシエチレンアルキルエーテル、高級アルコールにエチレンオキシドを付加重合させたポリオキシエチレンアルコールエーテル、モノ脂肪酸グリセリンにエチレンオキシドを付加重合させたポリオキシエチレングリセリン脂肪酸エステル、ソルビタン脂肪酸（又はソルビトール脂肪酸）にエチレンオキシドを付加重合させたポリオキシエチレンソルビタン（又はソルビトール）脂肪酸エステル、ポリエチレングリコールの一端の水酸基が脂肪酸でエステル化されたポリエチレングリコール脂肪酸エステル等を挙げることができる。さらに、両イオン性として、アルキルベタイン、アミンオキサイド等を挙げることができる。
第１の製造方法に用いられる第１のｐＨ調整剤としては特に制限はないが、例えば、塩酸、硝酸、硫酸、酢酸等の酸（無機酸であってもよく、有機酸であってもよい）又はアンモニア水、水酸化ナトリウム、水酸化カルシウム等の塩基を挙げることができる。中でも、作業のしやすいゲル化時間とする観点から、塩酸や、アンモニア水等を用いることが好ましい。
次いで、第１の製造方法においては、原料ゾルの粘度が１００〜２００００ｍＰａ・ｓの範囲で所望の値になったところで、原料ゾルを機械的に攪拌して、気泡が導入されたゾル多孔体を形成する。
気泡を導入するタイミング（導入時の原料ゾルの粘度）によって、得られる無機質多孔体の気孔構造を構成する気孔の形状、大きさを制御することができる。原料ゾルの粘度が低いほど、細い骨格が三次元構造を形成した連通した気孔が発達しやすく、原料ゾルの粘度が高いほど、独立した気孔を形成し易い。原料ゾルの粘度としては前述のように１００〜２００００ｍＰａ・ｓの範囲の中で適宜選択することが可能で、１００ｍＰａ・ｓ未満であると、ゲル化の速度よりも早く気孔構造が消失しやすく、全体として均質な気孔構造を得ることが困難であり、２００００ｍＰａ・ｓを超えると、気泡の導入のための攪拌が困難になる。
なお、少なくともその一部が球状である多数の連通した気孔からなる気孔構造を有する第１の無機質多孔体を製造する場合は、原料ゾルの粘度として、１００〜１０００ｍＰａ・ｓの範囲を選択することが好ましく、少なくともその一部が球状である多数の独立した気孔からなる気孔構造を有する第２の無機質多孔体を製造する場合は、原料ゾルの粘度として、１０００〜２００００ｍＰａ・ｓの範囲を選択することが好ましい。
機械的な攪拌により原料ゾル中に取り込まれた空気が原料ゾルの膜に覆われて泡となり気孔を形成（ゾル多孔体を形成）するが、界面活性剤は、その際に気体と液体の界面とを安定して存在させる役割を果たす。
機械的に攪拌する方法としては特に制限はないが、例えば、攪拌機（ミキサー）、ホイッパー、発泡機等による機械的攪拌を挙げることができる。また、ガス噴入等によって気泡を導入してもよい。攪拌時間としては特に制限はないが、例えば、０．１〜６０分間が好ましく、０．５〜３０分間がさらに好ましい。攪拌時間が０．１分間未満であると、気泡が十分に発達せず、６０分間を超えると、ゾルの粘度の時間変化により、攪拌中にゲル化が起こり、できあがった気孔構造を破壊してしまうことがある。なお、市販の発泡機（例えば、食品用に用いられる連続発泡機）を用いることによって、気孔構造の比重を制御することができるので、無機多孔体の比重を容易に制御することができる。
次いで、第１の製造方法においては、得られたゾル多孔体を、必要に応じ所定温度で加熱して、ゲル化させ、ゲル多孔体を形成する。上述のように気泡を導入する際の原料ゾルの粘度で、最終的に気孔構造を構成することになる気孔の形状や大きさを制御することができるが、ゲル化前に気泡の導入によって形成された気孔は放置しておくとその形状を維持できず、いずれは消滅することになるので、その気泡の消滅を抑制するために、さらにゲル化を促進させる処理（加熱処理）をすることが好ましい。なお、ゲル多孔体を得るために加熱をすることは必ずしも必須の処理ではないが、気孔構造をより制御し易くするためには加熱をする方が好ましい。この場合、加熱温度は、調製及び攪拌時のゾルの温度よりも５〜３０℃高い温度が好ましく、調製及び攪拌時のゾルの温度よも１０〜２５℃高い温度がさらに好ましい。
ゲル化後（ゲル多孔体形成後）、ゲル多孔体を乾燥して、乾燥ゲル多孔体を形成し、得られた乾燥ゲル多孔体を熱処理するが、その際には、乾燥中の急激な収縮によるクラックの発生を防ぐため、ゲル多孔体を、温度と湿度を保持したまま静置して熟成して、熟成ゲル多孔体を形成し、得られた熟成ゲル多孔体を、温度を保持したまま、湿度を下げて予備乾燥して、予備乾燥ゲル多孔体を形成し、予備乾燥ゲル多孔体を乾燥して、乾燥ゲル多孔体を形成し、得られた乾燥ゲル多孔体を熱処理することが好ましい。
例えば、一晩以上、ゲル化時（ゲル多孔体形成時）の温度より１０℃高い温度〜ゲル化時（ゲル多孔体形成時）の温度より１０℃低い温度の範囲内の温度で湿度を保持した状態で熟成し、温度を保持した状態で湿度を徐々に低下させながら予備乾燥後（一晩以上）、後述する所定温度、時間で、本乾燥し、さらに、後述する所定温度で、加熱処理することが好ましい。熟成時間は長いほどゲル骨格構造が発達して強固なものとなるため、その後の乾燥、熱処理、焼成時のクラック等の発生を有効に抑制することができる。このような熟成方法の具体例としては、例えば、ゾル多孔体を入れたビーカーを、パラフィン製のフィルムで密閉して所定の温度、例えば、４０℃の恒温槽に静置させることを挙げることができる。予備乾燥時の湿度の低下速度は遅ければ遅いほど、無機質多孔体におけるクラックの発生を抑制することができるため好ましい。予備乾燥を施したゲル多孔体は、本乾燥を行うが、このようなゲル多孔体を乾燥する方法としては特に制限はなく、例えば、室温で放置することにより自然に乾燥してもよく、また、オーブンや炉等の乾燥機中に静置した状態で乾燥してもよく、さらに、加温気流中で乾燥してもよい。本乾燥時の温度は、予備乾燥時の温度〜予備乾燥時の温度より１５０℃高い温度の範囲内の温度が好ましい。加熱処理時の昇温速度等は遅ければ遅いほど、無機質多孔体におけるクラックの発生を減少させることができるため好ましい。このような加熱処理は有機物（第１の界面活性剤）の分解を行うことが目的であるため、加熱処理温度は３００〜７００℃が好ましく、４００〜６００℃がさらに好ましい。３００℃未満であると、有機物の分解が不十分になることがあり、７００℃を超えると、焼結が進みすぎることがある。
第１の製造方法においては、上述のようにゲル多孔体を加熱処理した後に、さらに焼成してもよい。このようなゲル多孔体を焼成する方法としては特に制限はなく、静置状態で行ってもよく、また、空気や酸素のような気流中で行ってもよい。また、焼成温度は、７００〜１４００℃が好ましく、８００〜１２００℃がさらに好ましい。焼成温度が７００℃未満であると、焼結が進まないことがあり、１４００℃を超えると、溶融することがある。焼成時間は、０．５〜１０時間が好ましく、１〜３時間がさらに好ましい。焼成時間が０．５時間未満であると、焼結が進まないことがあり、１０時間を超えると、緻密化が進み気孔構造が崩壊することがある。なお、シリカを主成分とする場合には、焼成温度は９５０℃を上限とすることが好ましい。９５０℃を超えると、結晶化が起こり、結晶化することで特性が変化する（例えば、熱膨張挙動などが著しく変化する）ことがある。
本発明の無機質多孔体の製造方法（第２の製造方法）は、一方で、金属酸化物ゾル及び／又は金属水酸化物ゾルと、第２の界面活性剤と、第２のｐＨ調整剤とを、その粘度が１００〜２００００ｍＰａ・ｓとなるようなｐＨと温度との条件で混合して、所定のゲル化時間を有する原料ゾルを調製し、他方で、金属酸化物、金属水酸化物及び金属炭酸塩からなる群から選ばれる少なくとも一種の原料粉末を含む原料粉末調製物を調製し、得られた原料ゾルと原料粉末調製物とを混合し、次いで、機械的に攪拌して、気泡が導入された粉末含有ゾル多孔体を形成し、得られた前記粉末含有ゾル多孔体を、必要に応じ所定温度で加熱して、ゲル化させ、粉末含有ゲル多孔体を形成し、得られた粉末含有ゲル多孔体を乾燥して、乾燥粉末含有ゲル多孔体を形成し、得られた前記乾燥粉末含有ゲル多孔体を熱処理することを特徴とする。
第２の製造方法においては、まず、一方で、金属酸化物ゾル及び／又は金属水酸化物ゾル（好適例として、シリカ（ＳｉＯ２）ゾル及び／又はチタニア（ＴｉＯ２）ゾルを挙げることができる）と、第２の界面活性剤と、第２のｐＨ調整剤とを、その粘度が１００〜２００００ｍＰａ・ｓとなるようなｐＨと温度との条件で混合して、所定のゲル化時間を有する原料ゾルを調製し、他方で、金属酸化物、金属水酸化物及び金属炭酸塩からなる群から選ばれる少なくとも一種の原料粉末を含む原料粉末調製物を調製する。この場合、原料粉末調製物として、金属酸化物、金属水酸化物及び金属炭酸塩からなる群から選ばれる少なくとも一種の原料粉末を含む粉末スラリーと、第３の界面活性剤と、第３のｐＨ調整剤とを、原料粉末の濃度が１重量％以上で、かつ原料ゾルと同じｐＨとなるような条件で混合して、原料スラリーを調製することが好ましい。なお、原料粉末の濃度は３０重量％以上であることがさらに好ましい。
次いで、得られた原料ゾルと原料粉末調製物（好ましくは、原料スラリー）とを混合し、次いで、機械的に攪拌して、気泡が導入された粉末含有ゾル多孔体を形成する。
次いで、得られた粉末含有ゾル多孔体を、必要に応じ所定温度で加熱して、ゲル化させ、粉末含有ゲル多孔体を形成し、
次いで、得られた前記粉末含有ゲル多孔体を乾燥して、乾燥粉末含有ゲル多孔体を形成する。
次いで、得られた前記乾燥粉末含有ゲル多孔体を熱処理する。
また、第２の製造方法においては、粉末含有ゲル多孔体を乾燥して、乾燥粉末含有ゲル多孔体を形成し、得られた乾燥粉末含有ゲル多孔体を熱処理する際に、粉末含有ゲル多孔体を、温度及び湿度を保持したまま静置して熟成して、熟成粉末含有ゲル多孔体を形成し、得られた熟成粉末含有ゲル多孔体を、温度を保持したまま、湿度を下げて予備乾燥して、予備乾燥粉末含有ゲル多孔体を形成し、予備乾燥粉末含有ゲル多孔体を乾燥して、乾燥粉末含有ゲル多孔体を形成し、得られた乾燥粉末含有ゲル多孔体を熱処理することが好ましい。
さらに、第２の製造方法においては、粉末含有ゲル多孔体を熱処理した後に、さらに焼成することが好ましい。
第２の製造方法で用いられる、原料ゾルを調製するための金属酸化物ゾル及び／又は金属水酸化物ゾルとしては、好適例として、シリカ（ＳｉＯ２）ゾル及び／又はチタニア（ＴｉＯ２）ゾルを挙げることができる。
また、第２の製造方法で用いられる原料粉末調製物（好ましくは、原料スラリー）は、金属酸化物、金属水酸化物及び金属炭酸塩からなる群から選ばれる少なくとも一種の原料粉末を含むものであることが焼成時の反応性の観点から好ましい。この場合、金属酸化物、金属水酸化物及び金属炭酸塩からなる群から選ばれる少なくとも一種の原料粉末は、ケイ素（Ｓｉ）、チタン（Ｔｉ）、アルミニウム（Ａｌ）及びアルカリ土類金属（Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｒａ）からなる群から選ばれる少なくとも一の元素の酸化物、水酸化物、金属炭酸塩及び／又はこれらの複合酸化物の粉末であることが焼成後に得られる生成物の制御がしやすいことから好ましい。
なお、第２の製造方法において、以下の事項は第１の製造方法と共通するのでその記載は省略する。
〔１〕原料ゾルの種類及びその調製方法
〔２〕第２の界面活性剤（第１の界面活性剤と同様）
〔３〕第２のｐＨ調整剤及び第３のｐＨ調整剤（第１のｐＨ調整剤と同様）
〔４〕ゲルの熟成・乾燥条件
第２の製造方法で、特記すべき事項は、以下の通りである。
〔１〕焼成温度：ゾルの種類と、原料粉末（好ましくは、粉末スラリーの形態）の種類との組み合わせによって（最終的に得られる化合物によって）、最適な焼成温度が変わることになる。具体的には、コージェライトの場合１３００〜１５００℃；ムライトの場合１１００〜１４００℃；フォルステライトの場合１３００〜１６００℃；アルミニウムチタネートの場合１４００〜１６００℃；シリカの場合７００〜１４００℃がそれぞれ好ましい。
〔２〕第３の界面活性剤：第１の界面活性剤及び第２の界面活性剤と共通のものを用いてもよいが、粉末の分散性を向上させる目的で、ポリアクリル酸アンモニウム塩、ポリカルボン酸ナトリウム塩、ポリカルボン酸アンモニウム塩等を添加したものを用いることが好ましい。中でも、ポリアクリル酸アンモニウム塩を添加したものがさらに好ましい。The inorganic porous body of the present invention is an inorganic porous body having a pore structure (three-dimensional network structure and / or sponge-like structure) composed of a large number of pores, at least a part of which is spherical, and the pores forming the pore structure The size is 5 μm to 2 mm, and the porosity is 60% or more.
The main component constituting the first inorganic porous body of the present invention is not particularly limited, but silica (SiO 2 ), titania (TiO 2 ), cordierite (Mg 2 Al 4 Si 5 O 18 ), mullite (3Al 2 O 3 · 2SiO 2 ), forsterite (Mg 2 SiO 4 ), and at least one selected from the group consisting of aluminum titanate (Al 2 TiO 5 ) are preferable, and the main component constituting the second inorganic porous body is Silica (SiO 2 ), titania (TiO 2 ), cordierite (Mg 2 Al 4 Si 5 O 18 ), mullite (3Al 2 O 3 · 2SiO 2 ), forsterite (Mg 2 SiO 4 ) and aluminum titanate (Al 2) At least one selected from the group consisting of TiO 5 ) is preferred. Silica (SiO 2 ), titania (TiO 2 ), cordierite (Mg 2 Al 4 Si 5 O 18 ), mullite (3Al 2 O 3 · 2SiO 2 ), forsterite (Mg 2 SiO 4 ), aluminum titanate (Al 2) TiO 5 ) is not particularly limited, but those having a polymorphic crystalline phase are amorphous (amorphous) in the case of silica (SiO 2 ) from the viewpoint of thermal expansion characteristics and catalytic characteristics. For example, in the case of titania (TiO 2 ), an anatase type, and in the case of aluminum titanate (Al 2 TiO 5 ), a low temperature type (β phase) can be mentioned as preferred examples. In the present invention, cordierite (Mg 2 Al 4 Si 5 O 18 ) includes Indianite that is polymorphic (having the same chemical composition but different crystal structure). These may be one kind alone, or may be a mixture of two or more kinds.
The first inorganic porous body of the present invention has a pore structure (three-dimensional network structure and / or sponge-like structure) composed of a large number of continuous pores, at least a part of which is spherical. The size of the pores needs to be 5 μm to 2 mm. If it is less than 5 μm, the gas permeation coefficient becomes small (when gas is permeated, the pressure loss becomes high), and if it exceeds 2 mm, the strength becomes small. Further, the first inorganic porous body of the present invention needs to have a porosity of 60% or more. When the porosity is less than 60%, the gas permeability coefficient becomes small (when the gas is permeated, the pressure loss becomes high). The gas permeability coefficient needs to be 1 × 10 −11 m 2 or more.
The second inorganic porous body of the present invention has a pore structure (sponge-like structure) composed of a large number of independent pores, at least a part of which is spherical. The size of the pores needs to be 5 μm to 2 mm. Even if the thickness is less than 5 μm, there is no problem in characteristics, but the amount of surfactant used to stabilize the foam increases, the load on the environment increases, and if it exceeds 2 mm, the mechanical strength decreases. Further, the porosity needs to be 60% or more, as in the case of the first inorganic porous body. In addition, it is necessary that the ratio of spherical pores ((volume of spherical pores / volume of all pores) × 100) among pores forming the pore structure is 60% or more. When it is less than 60%, the thermal conductivity is increased. The thermal conductivity needs to be 0.07 W / mK or less.
Further, the first inorganic porous body and the second inorganic porous body of the present invention are mainly composed of silica, have a thermal expansion coefficient of 2 × 10 −6 K −1 or less, and a bending strength of 1 MPa or more. preferable. When the thermal expansion coefficient exceeds 2 × 10 −6 K −1 , there may be a problem in thermal shock resistance. Further, if the bending strength is less than 1 MPa, it may not be used as a structural material or a problem may be caused in thermal shock resistance.
The first inorganic porous body and the second inorganic porous body of the present invention are mainly composed of cordierite (Mg 2 Al 4 Si 5 O 18 ) and have a thermal expansion coefficient of 2.2 × 10 −6 K −. It is preferably 1 or less and the bending strength is 0.5 MPa or more. When the thermal expansion coefficient exceeds 2.2 × 10 −6 K −1 , there may be a problem in thermal shock resistance. Further, if the bending strength is less than 0.5 MPa, it may not be used as a structural material or a problem may be caused in thermal shock resistance.
The first inorganic porous body of the present invention has a small coefficient of thermal expansion and excellent bending strength, and has a gas permeability coefficient as large as 1 × 10 −11 m 2 or more. When gas is permeated, the pressure loss is reduced. Therefore, it is suitably used for applications such as filters.
The second inorganic porous body of the present invention has a low thermal expansion coefficient and excellent bending strength, and also has a low thermal conductivity of 0.07 W / mK or less and excellent heat insulation, so it is suitable for applications such as heat insulating materials. Used for.
The method for producing an inorganic porous body of the present invention (first production method) includes a metal oxide sol and / or a metal hydroxide sol, a first surfactant, and a first pH adjuster. Mixing under conditions of pH and temperature such that the viscosity is 100 to 20000 mPa · s to prepare a raw material sol having a predetermined gelation time, mechanically stirring the obtained raw material sol, The sol porous body into which the sol is introduced is heated and gelled by heating the obtained sol porous body at a predetermined temperature, the gel porous body is dried, and the obtained gel porous body is dried to obtain a dried gel A porous body is formed, and the obtained dried gel porous body is heat-treated.
In the first production method, first, a metal oxide sol and / or a metal hydroxide sol (preferred examples include silica (SiO 2 ) sol and titania (TiO 2 ) sol), The raw material sol having a predetermined gelation time is prepared by mixing the surfactant and the first pH adjuster under conditions of pH and temperature such that the viscosity is 100 to 20000 mPa · s. .
Hereinafter, a case where silica (SiO 2 ) sol and / or titania (TiO 2 ) sol is used as the metal oxide sol and / or metal hydroxide sol will be described.
Usually, in silica (SiO 2 ) sol and / or titania (TiO 2 ) sol, sol particles (particles of several nanometers to several tens of nanometers of silica or titania) are monodispersed in a solvent (water). In many cases, it is used for various purposes, and therefore, it has been devised so that the monodispersed state can be stably maintained for a long time. When this state becomes unstable, the particles aggregate, and the aggregation spreads over the entire sol, resulting in gelation (the whole solidifies in a jelly state and the viscosity becomes extremely high). . The change in viscosity until gelation gradually increases on the order of several months to several years, but it is forcibly accelerated so as to be on the order of several minutes to several hours. It is one feature of the first production method that the gel is gelled.
In general, the driving force for gelling the sol can be obtained by creating a state in which sol aggregation is likely to occur. That is, [1] decrease in surface potential by adjusting pH, [2] increase in collision frequency between sol particles due to temperature increase, [3] increase in collision frequency between sol particles due to concentration increase, [4] surface due to addition of electrolyte The sol is likely to aggregate due to destabilization of the potential state and the like, and gelation is promoted. In the first production method, the addition of the first pH adjusting agent promotes gelation by the action of [1] (also [4] in some cases), and the heating is by the action of [2]. Each corresponds to the promotion of gelation.
As described above, as a method for forcibly increasing the time change of the viscosity of the raw material sol (controlling so that the raw material sol gels in a predetermined time), a method by controlling pH and temperature is a first production method. I use it. In normal silica sol, pH is about 10 (titania sol is about pH = 1), but by controlling the pH of raw material sol to 5-7 (titania sol is pH = 2-4), gelation (viscosity is tens of thousands). The time (mPa · s) is several minutes to several hours. Further, when the temperature is increased, the gelation time is advanced (the gelation time decreases in inverse proportion to the temperature). For example, when the silica sol is pH = 6, the gelation time is about 40 to 60 minutes at a temperature of 20 ° C., but it is about a quarter to about 10 to 30 minutes at 40 ° C. Further, the gelation can be rapidly carried out by heating to 40 ° C. while the gelation proceeds at 20 ° C.
The gelation time controlled by the above method is usually preferably from 1 minute to 1 hour, and more preferably from several minutes to several tens of minutes from the viewpoint of ease of work. Further, the temperature may be changed after bubbles are introduced into the raw material sol to form pores. By doing so, the pore structure can be instantly gelled while maintaining the state at the time of formation, and the shape and size of the pores constituting the pore structure can be easily controlled.
By controlling the gelation time (controlling the change in viscosity with time) as described above, the viscosity when introducing bubbles to be described later can be arbitrarily selected within the range of 100 to 20000 mPa · s. That is, after preparing a sol with a predetermined composition, it is preferable to measure a change in viscosity of the sol at a constant temperature (for example, 20 ° C.).
Thus, in the first production method, it is important to adjust the viscosity of the raw material sol when introducing bubbles to be described later in the range of 100 to 20000 mPa · s. Any combination can be used as long as the viscosity can be in such a range.
Here, the silica (SiO 2 ) sol and / or titania (TiO 2 ) sol used in the first production method is not particularly limited as long as it gels under predetermined conditions. A preferable example is one having a diameter of 10 nm and a concentration of 30%. Any one of silica (SiO 2 ) sol and titania (TiO 2 ) sol may be used alone, or a mixture of two may be used. The concentration of the silica (SiO 2 ) sol and titania (TiO 2 ) sol may be any commercially available concentration, but if it is too thin, the mechanical strength after gelation is weak and the shape can be maintained. Since it is difficult, 20% or more is preferable.
The first surfactant used in the first production method is one that is rich in foaming properties, and can form stable pores by introducing bubbles into the obtained raw material sol. Any of anionic, cationic, nonionic and amphoteric may be used, but a linear surfactant is preferable. Moreover, the nonionic thing which does not affect pH is preferable. Furthermore, the thing which does not contain an alkali metal etc. is preferable so that an impurity may not remain after calcination. Specifically, as an anionic surfactant, fatty acid salt, alkyl sulfate ester salt, polyoxyethylene alkyl ether sulfate ester salt, alkylbenzene sulfonate, alkyl naphthalene sulfonate, alkyl sulfosuccinate, alkyl diphenyl ether disulfone And acid salts, alkyl phosphates, and polycarboxylates. Further, as a cationic surfactant, an aliphatic quaternary ammonium salt having a higher alkyl group and a lower alkyl group such as hexadecylcetyltrimethylammonium chloride, an aliphatic amine salt having a higher alkyl group and a lower alkyl group, etc. Can be mentioned. In addition, as nonionic surfactants, polyoxyethylene alkyl ethers having higher alkyl groups and oxyethylene groups, polyoxyethylene alcohol ethers obtained by addition polymerization of ethylene oxide to higher alcohols, and addition polymerization of ethylene oxide to mono fatty acid glycerin. Polyoxyethylene glycerin fatty acid ester, polyoxyethylene sorbitan (or sorbitol) fatty acid ester obtained by addition polymerization of ethylene oxide to sorbitan fatty acid (or sorbitol fatty acid), polyethylene glycol fatty acid ester in which one hydroxyl group of polyethylene glycol is esterified with fatty acid Etc. Furthermore, examples of amphoteric properties include alkyl betaines and amine oxides.
Although there is no restriction | limiting in particular as a 1st pH adjuster used for a 1st manufacturing method, For example, acids (an inorganic acid may be sufficient as hydrochloric acid, nitric acid, a sulfuric acid, an acetic acid, and an organic acid may be sufficient as it) ) Or bases such as aqueous ammonia, sodium hydroxide, and calcium hydroxide. Among these, hydrochloric acid, aqueous ammonia, or the like is preferably used from the viewpoint of making the gelation time easy to work.
Next, in the first production method, when the viscosity of the raw material sol reaches a desired value in the range of 100 to 20000 mPa · s, the raw material sol is mechanically stirred to obtain a porous sol body into which bubbles are introduced. Form.
The shape and size of the pores constituting the pore structure of the obtained inorganic porous body can be controlled by the timing of introducing the bubbles (viscosity of the raw material sol at the time of introduction). The lower the viscosity of the raw material sol, the easier it is to develop continuous pores in which a thin skeleton forms a three-dimensional structure, and the higher the viscosity of the raw material sol, the easier it is to form independent pores. As described above, the viscosity of the raw material sol can be appropriately selected within the range of 100 to 20000 mPa · s. When the viscosity is less than 100 mPa · s, the pore structure is likely to disappear faster than the gelation speed. It is difficult to obtain a homogeneous pore structure as a whole, and if it exceeds 20000 mPa · s, stirring for introducing bubbles becomes difficult.
In addition, when manufacturing the 1st inorganic porous body which has a pore structure which consists of many continuous pores in which at least a part is spherical, select the range of 100 to 1000 mPa · s as the viscosity of the raw material sol. In the case of producing a second inorganic porous body having a pore structure composed of a large number of independent pores, at least a part of which is spherical, a range of 1000 to 20000 mPa · s is selected as the viscosity of the raw material sol. It is preferable.
The air taken into the raw material sol by mechanical stirring is covered with a film of the raw material sol, forming bubbles and forming pores (forming a sol porous body). And play a role to make it exist stably.
Although there is no restriction | limiting in particular as a method stirred mechanically, For example, the mechanical stirring by a stirrer (mixer), a whipper, a foaming machine etc. can be mentioned. Further, bubbles may be introduced by gas injection or the like. Although there is no restriction | limiting in particular as stirring time, For example, 0.1 to 60 minutes are preferable and 0.5 to 30 minutes are more preferable. If the stirring time is less than 0.1 minutes, bubbles do not develop sufficiently, and if it exceeds 60 minutes, gelation occurs during stirring due to the change in the viscosity of the sol, and the resulting pore structure is destroyed. It may end up. In addition, since the specific gravity of the pore structure can be controlled by using a commercially available foaming machine (for example, a continuous foaming machine used for foods), the specific gravity of the inorganic porous body can be easily controlled.
Next, in the first manufacturing method, the obtained sol porous body is heated at a predetermined temperature as necessary to be gelled, thereby forming a gel porous body. As mentioned above, the viscosity of the raw material sol when introducing bubbles can control the shape and size of the pores that will eventually form the pore structure, but it is formed by introducing bubbles before gelation. If the left pores are left unattended, their shape cannot be maintained, and eventually they will disappear. Therefore, in order to suppress the disappearance of the bubbles, a treatment (heating treatment) that further promotes gelation may be performed. preferable. Note that heating to obtain the gel porous body is not necessarily an essential treatment, but heating is preferable in order to make the pore structure easier to control. In this case, the heating temperature is preferably 5 to 30 ° C. higher than the sol temperature during preparation and stirring, and more preferably 10 to 25 ° C. higher than the sol temperature during preparation and stirring.
After gelation (after gel porous body formation), the gel porous body is dried to form a dry gel porous body, and the resulting dried gel porous body is heat-treated, but in that case, rapid shrinkage during drying In order to prevent the generation of cracks due to aging, the gel porous body is left standing and aging while maintaining the temperature and humidity to form an aging gel porous body, and the obtained aging gel porous body is maintained while maintaining the temperature. It is preferable to reduce the humidity and perform preliminary drying to form a preliminary dried gel porous body, dry the preliminary dried gel porous body to form a dried gel porous body, and heat-treat the resulting dried gel porous body .
For example, the humidity is maintained at a temperature in the range of 10 ° C. higher than the temperature at the time of gelation (when the gel porous body is formed) to 10 ° C. lower than the temperature at the time of gelation (when the gel porous body is formed). After pre-drying (overnight or more) while gradually lowering the humidity while maintaining the temperature, the film is dried at a predetermined temperature and time, which will be described later, and further heated at a predetermined temperature, which will be described later. It is preferable to do. As the aging time is longer, the gel skeleton structure develops and becomes stronger, so that generation of cracks during subsequent drying, heat treatment, and firing can be effectively suppressed. As a specific example of such an aging method, for example, a beaker containing a sol porous body is sealed with a paraffin film and allowed to stand in a thermostat at a predetermined temperature, for example, 40 ° C. it can. The slower the rate of decrease in humidity during preliminary drying, the more preferable it is because cracks in the inorganic porous body can be suppressed. The preliminarily dried gel porous body is subjected to main drying, but there is no particular limitation on the method for drying such a gel porous body. For example, the gel porous body may be naturally dried by being left at room temperature. Further, it may be dried in a stationary state in a dryer such as an oven or a furnace, or may be dried in a heated air stream. The temperature during the main drying is preferably a temperature within the range of 150 ° C. higher than the temperature during preliminary drying to the temperature during preliminary drying. The slower the rate of temperature rise during the heat treatment, the lower the occurrence of cracks in the inorganic porous body. Since such heat treatment is intended to decompose the organic substance (first surfactant), the heat treatment temperature is preferably 300 to 700 ° C, more preferably 400 to 600 ° C. When the temperature is lower than 300 ° C., decomposition of the organic matter may be insufficient, and when the temperature exceeds 700 ° C., the sintering may proceed excessively.
In the first manufacturing method, the gel porous body may be further baked after being heat-treated as described above. There is no restriction | limiting in particular as a method of baking such a gel porous body, You may carry out in a stationary state and you may carry out in airflow, such as air and oxygen. Moreover, 700-1400 degreeC is preferable and baking temperature is more preferable 800-1200 degreeC. If the firing temperature is less than 700 ° C, sintering may not proceed, and if it exceeds 1400 ° C, it may melt. The firing time is preferably 0.5 to 10 hours, and more preferably 1 to 3 hours. If the firing time is less than 0.5 hours, sintering may not proceed. If it exceeds 10 hours, densification proceeds and the pore structure may collapse. When silica is the main component, the firing temperature is preferably 950 ° C. When it exceeds 950 ° C., crystallization occurs, and the characteristics may change due to crystallization (for example, the thermal expansion behavior may change significantly).
On the other hand, the method for producing an inorganic porous body of the present invention (second production method) includes a metal oxide sol and / or a metal hydroxide sol, a second surfactant, and a second pH adjuster. Are mixed under conditions of pH and temperature such that the viscosity is 100 to 20000 mPa · s to prepare a raw material sol having a predetermined gelation time. On the other hand, a metal oxide, a metal hydroxide, and A raw material powder preparation containing at least one raw material powder selected from the group consisting of metal carbonates is prepared, the obtained raw material sol and the raw material powder preparation are mixed, and then mechanically stirred to form bubbles. The introduced powder-containing sol porous body is formed, and the obtained powder-containing sol porous body is heated at a predetermined temperature as necessary to be gelled to form a powder-containing gel porous body, and the obtained powder Dry gel containing porous material Forming a, characterized by heat-treating the resulting said dry powder containing gel porous body.
In the second production method, first, on the other hand, metal oxide sol and / or metal hydroxide sol (preferred examples include silica (SiO 2 ) sol and / or titania (TiO 2 ) sol). ), The second surfactant, and the second pH adjuster are mixed under conditions of pH and temperature such that the viscosity is 100 to 20000 mPa · s, and have a predetermined gelation time. A raw material sol is prepared, and on the other hand, a raw material powder preparation containing at least one raw material powder selected from the group consisting of metal oxides, metal hydroxides and metal carbonates is prepared. In this case, as a raw material powder preparation, a powder slurry containing at least one raw material powder selected from the group consisting of metal oxides, metal hydroxides and metal carbonates, a third surfactant, and a third pH It is preferable to prepare a raw material slurry by mixing the adjusting agent under conditions such that the concentration of the raw material powder is 1% by weight or more and the same pH as the raw material sol. The concentration of the raw material powder is more preferably 30% by weight or more.
Next, the obtained raw material sol and raw material powder preparation (preferably, raw material slurry) are mixed and then mechanically stirred to form a powder-containing sol porous body into which bubbles are introduced.
Next, the obtained powder-containing sol porous body is heated at a predetermined temperature as necessary to be gelled to form a powder-containing gel porous body,
Next, the obtained powder-containing gel porous body is dried to form a dry powder-containing gel porous body.
Next, the obtained dry powder-containing gel porous body is heat-treated.
In the second production method, the powder-containing gel porous body is formed by drying the powder-containing gel porous body to form a dry powder-containing gel porous body, and heat-treating the obtained dry powder-containing gel porous body. Aged and powdered gel porous body is formed while maintaining the temperature and humidity, and the aged powder-containing gel porous body is preliminarily dried by lowering the humidity while maintaining the temperature. Forming a pre-dried powder-containing gel porous body, drying the pre-dried powder-containing gel porous body to form a dry powder-containing gel porous body, and heat-treating the obtained dry powder-containing gel porous body preferable.
Furthermore, in the second manufacturing method, it is preferable that the powder-containing gel porous body is further baked after being heat-treated.
As a metal oxide sol and / or metal hydroxide sol used in the second production method for preparing a raw material sol, silica (SiO 2 ) sol and / or titania (TiO 2 ) sol are preferable examples. Can be mentioned.
Moreover, the raw material powder preparation (preferably, raw material slurry) used in the second production method contains at least one raw material powder selected from the group consisting of metal oxides, metal hydroxides and metal carbonates. Is preferable from the viewpoint of reactivity during firing. In this case, at least one raw material powder selected from the group consisting of metal oxide, metal hydroxide, and metal carbonate is silicon (Si), titanium (Ti), aluminum (Al), and alkaline earth metal (Mg, A product obtained after firing to be a powder of an oxide, hydroxide, metal carbonate and / or composite oxide of at least one element selected from the group consisting of Ca, Sr, Ba, Ra) It is preferable because it is easy to control.
In the second manufacturing method, the following items are the same as those in the first manufacturing method, and thus the description thereof is omitted.
[1] Kind of raw material sol and its preparation method [2] Second surfactant (similar to the first surfactant)
[3] Second pH adjusting agent and third pH adjusting agent (similar to the first pH adjusting agent)
[4] Maturation and drying conditions of gel The matters to be noted in the second production method are as follows.
[1] Calcination temperature: The optimum calcination temperature varies depending on the combination of the type of sol and the type of raw material powder (preferably in the form of a powder slurry) (depending on the compound finally obtained). Specifically, 1300-1500 ° C for cordierite; 1100-1400 ° C for mullite; 1300-1600 ° C for forsterite; 1400-1600 ° C for aluminum titanate; 700-1400 ° C for silica. .
[2] Third surfactant: The same surfactant as the first surfactant and the second surfactant may be used, but for the purpose of improving the dispersibility of the powder, an ammonium polyacrylate salt, It is preferable to use a polycarboxylic acid sodium salt, a polycarboxylic acid ammonium salt or the like. Especially, what added the polyacrylic acid ammonium salt is still more preferable.
以下、本発明を実施例によってさらに具体的に説明する。 Hereinafter, the present invention will be described more specifically with reference to examples.
シリカゾル（日産化学（株）製、商品名：スノーテックスＳ）、ｐＨ調整剤として塩酸、界面活性剤としてラウリル硫酸エステルナトリウム塩を用いた。シリカゾル１００ｇ（ｐＨ＝１０）に対して塩酸をｐＨ＝６となるように添加し（１．２５ｍｌ程度）、さらに、界面活性剤を０．５ｍｌ添加した。この原料ゾルを２０℃に保ったウオーターバス内で静かに攪拌し、粘度が１００ｍＰａ・ｓになったところで、室温下、１リットルのビーカー中で機械的攪拌（ミキサー、１分間）を行い、ビーカーを、パラフィン製のフィルムで密閉して４０℃の恒温槽に静置させた。そのまま３日静置した後、ビーカーのフィルムに直径１ｍｍ程度のピンホールを１つ開け、さらに３日静置した。その後、フィルムを外し、１日静置した。得られた乾燥体を、６００℃で４時間、さらに８５０℃で２時間、大気中で加熱処理し、シリカ質多孔体を得た。得られた多孔体の種類、気孔の大きさ、気孔率、球状気孔の占める割合、ガス透過係数、熱伝導率、曲げ強度、及び熱膨張係数を表１に示す。 Silica sol (manufactured by Nissan Chemical Co., Ltd., trade name: Snowtex S), hydrochloric acid as a pH adjuster, and sodium lauryl sulfate as a surfactant were used. To 100 g of silica sol (pH = 10), hydrochloric acid was added so that pH = 6 (about 1.25 ml), and 0.5 ml of surfactant was further added. The raw material sol was gently stirred in a water bath maintained at 20 ° C. When the viscosity reached 100 mPa · s, mechanical stirring (mixer, 1 minute) was performed in a 1 liter beaker at room temperature. Was sealed with a paraffin film and allowed to stand in a constant temperature bath at 40 ° C. After leaving still for 3 days, a pinhole having a diameter of about 1 mm was opened in the beaker film, and the plate was further left for 3 days. Thereafter, the film was removed and allowed to stand for 1 day. The obtained dried body was heat-treated in the atmosphere at 600 ° C. for 4 hours and further at 850 ° C. for 2 hours to obtain a siliceous porous body. Table 1 shows the type of porous body, pore size, porosity, proportion of spherical pores, gas permeability coefficient, thermal conductivity, bending strength, and thermal expansion coefficient.
シリカゾル（日産化学（株）製、商品名：スノーテックスＳ）、ｐＨ調整剤として塩酸、界面活性剤としてラウリル硫酸エステルナトリウム塩を用いた。シリカゾル１００ｇ（ｐＨ＝１０）に対して塩酸をｐＨ＝６となるように添加し（１．２５ｍｌ程度）、さらに、界面活性剤を０．５ｍｌ添加した。この原料ゾルを２０℃に保ったウオーターバス内で静かに攪拌し、粘度が３００ｍＰａ・ｓになったところで、室温下、１リットルのビーカー中で機械的攪拌（ミキサー、１分間）を行い、ビーカーを、パラフィン製のフィルムで密閉して４０℃の恒温槽に静置させた。そのまま３日静置した後、ビーカーのフィルムに直径１ｍｍ程度のピンホールを１つ開け、さらに３日静置した。その後フィルムを外し、１日静置した。得られた乾燥体を、６００℃で４時間、さらに８５０℃で２時間、大気中で加熱処理し、シリカ質多孔体を得た。得られた多孔体の種類、気孔の大きさ、気孔率、球状気孔の占める割合、ガス透過係数、熱伝導率、曲げ強度、及び熱膨張係数を表１に示す。 Silica sol (manufactured by Nissan Chemical Co., Ltd., trade name: Snowtex S), hydrochloric acid as a pH adjuster, and sodium lauryl sulfate as a surfactant were used. To 100 g of silica sol (pH = 10), hydrochloric acid was added so that pH = 6 (about 1.25 ml), and 0.5 ml of surfactant was further added. The raw material sol was gently stirred in a water bath maintained at 20 ° C., and when the viscosity reached 300 mPa · s, mechanical stirring (mixer, 1 minute) was performed in a 1 liter beaker at room temperature. Was sealed with a paraffin film and allowed to stand in a constant temperature bath at 40 ° C. After leaving still for 3 days, a pinhole having a diameter of about 1 mm was opened in the beaker film, and the plate was further left for 3 days. Thereafter, the film was removed and allowed to stand for 1 day. The obtained dried body was heat-treated in the atmosphere at 600 ° C. for 4 hours and further at 850 ° C. for 2 hours to obtain a siliceous porous body. Table 1 shows the type of porous body, pore size, porosity, proportion of spherical pores, gas permeability coefficient, thermal conductivity, bending strength, and thermal expansion coefficient.
シリカゾル（日産化学（株）製、商品名：スノーテックスＳ）、ｐＨ調整剤として塩酸、界面活性剤としてラウリル硫酸エステルナトリウム塩を用いた。シリカゾル１００ｇ（ｐＨ＝１０）に対して塩酸をｐＨ＝６となるように添加し（１．２５ｍｌ程度）、さらに、界面活性剤を０．５ｍｌ添加した。この原料ゾルを２０℃に保ったウオーターバス内で静かに攪拌し、粘度が５００ｍＰａ・ｓになったところで、室温下、１リットルのビーカー中で機械的攪拌（ミキサー、１分間）を行い、ビーカーを、パラフィン製のフィルムで密閉して４０℃の恒温槽に静置させた。そのまま３日静置した後、ビーカーのフィルムに直径１ｍｍ程度のピンホールを１つ開け、さらに３日静置した。その後フィルムを外し、１日静置した。得られた乾燥体を、６００℃で４時間、さらに８５０℃で２時間、大気中で加熱処理し、シリカ質多孔体を得た。得られた多孔体の種類、気孔の大きさ、気孔率、球状気孔の占める割合、ガス透過係数、熱伝導率、曲げ強度、及び熱膨張係数を表１に示す。 Silica sol (manufactured by Nissan Chemical Co., Ltd., trade name: Snowtex S), hydrochloric acid as a pH adjuster, and sodium lauryl sulfate as a surfactant were used. To 100 g of silica sol (pH = 10), hydrochloric acid was added so that pH = 6 (about 1.25 ml), and 0.5 ml of surfactant was further added. The raw material sol was gently stirred in a water bath maintained at 20 ° C. When the viscosity reached 500 mPa · s, mechanical stirring (mixer, 1 minute) was performed in a 1 liter beaker at room temperature. Was sealed with a paraffin film and allowed to stand in a constant temperature bath at 40 ° C. After leaving still for 3 days, a pinhole having a diameter of about 1 mm was opened in the beaker film, and the plate was further left for 3 days. Thereafter, the film was removed and allowed to stand for 1 day. The obtained dried body was heat-treated in the atmosphere at 600 ° C. for 4 hours and further at 850 ° C. for 2 hours to obtain a siliceous porous body. Table 1 shows the type of porous body, pore size, porosity, proportion of spherical pores, gas permeability coefficient, thermal conductivity, bending strength, and thermal expansion coefficient.
シリカゾル（日産化学（株）製、商品名：スノーテックスＳ）、ｐＨ調整剤として塩酸、界面活性剤としてラウリル硫酸エステルナトリウム塩を用いた。シリカゾル１００ｇ（ｐＨ＝１０）に対して塩酸をｐＨ＝６となるように添加し（１．２５ｍｌ程度）、さらに、界面活性剤を０．５ｍｌ添加した。この原料ゾルを２０℃に保ったウオーターバス内で静かに攪拌し、粘度が２０００ｍＰａ・ｓになったところで、室温下、１リットルのビーカー中で機械的攪拌（ミキサー、１分間）を行い、ビーカーを、パラフィン製のフィルムで密閉して４０℃の恒温槽に静置させた。そのまま３日静置した後、ビーカーのフィルムに直径１ｍｍ程度のピンホールを１つ開け、さらに３日静置した。その後フィルムを外し、１日静置した。得られた乾燥体を、６００℃で４時間、さらに８５０℃で２時間、大気中で加熱処理し、シリカ質多孔体を得た。得られた多孔体の種類、気孔の大きさ、気孔率、球状気孔の占める割合、ガス透過係数、熱伝導率、曲げ強度、及び熱膨張係数を表１に示す。 Silica sol (manufactured by Nissan Chemical Co., Ltd., trade name: Snowtex S), hydrochloric acid as a pH adjuster, and sodium lauryl sulfate as a surfactant were used. To 100 g of silica sol (pH = 10), hydrochloric acid was added so that pH = 6 (about 1.25 ml), and 0.5 ml of surfactant was further added. The raw material sol was gently stirred in a water bath maintained at 20 ° C., and when the viscosity reached 2000 mPa · s, mechanical stirring (mixer, 1 minute) was performed in a 1 liter beaker at room temperature. Was sealed with a paraffin film and allowed to stand in a constant temperature bath at 40 ° C. After leaving still for 3 days, a pinhole having a diameter of about 1 mm was opened in the beaker film, and the plate was further left for 3 days. Thereafter, the film was removed and allowed to stand for 1 day. The obtained dried body was heat-treated in the atmosphere at 600 ° C. for 4 hours and further at 850 ° C. for 2 hours to obtain a siliceous porous body. Table 1 shows the type of porous body, pore size, porosity, proportion of spherical pores, gas permeability coefficient, thermal conductivity, bending strength, and thermal expansion coefficient.
シリカゾル（日産化学（株）製、商品名：スノーテックスＳ）、ｐＨ調整剤として塩酸、界面活性剤としてラウリル硫酸エステルナトリウム塩を用いた。シリカゾル１００ｇ（ｐＨ＝１０）に対して塩酸をｐＨ＝６となるように添加し（１．２５ｍｌ程度）、さらに、界面活性剤を０．５ｍｌ添加した。この原料ゾルを２０℃に保ったウオーターバス内で静かに攪拌し、粘度が１００００ｍＰａ・ｓになったところで、室温下、１リットルのビーカー中で機械的攪拌（ミキサー、１分間）を行い、ビーカーを、パラフィン製のフィルムで密閉して４０℃の恒温槽に静置させた。そのまま３日静置した後、ビーカーのフィルムに直径１ｍｍ程度のピンホールを１つ開け、さらに３日静置した。その後フィルムを外し、１日静置した。得られた乾燥体を、６００℃で４時間、さらに８５０℃で２時間、大気中で加熱処理し、シリカ質多孔体を得た。得られた多孔体の種類、気孔の大きさ、気孔率、球状気孔の占める割合、ガス透過係数、熱伝導率、曲げ強度、及び熱膨張係数を表１に示す。 Silica sol (manufactured by Nissan Chemical Co., Ltd., trade name: Snowtex S), hydrochloric acid as a pH adjuster, and sodium lauryl sulfate as a surfactant were used. To 100 g of silica sol (pH = 10), hydrochloric acid was added so that pH = 6 (about 1.25 ml), and 0.5 ml of surfactant was further added. The raw material sol was gently stirred in a water bath maintained at 20 ° C., and when the viscosity reached 10000 mPa · s, mechanical stirring (mixer, 1 minute) was performed in a 1 liter beaker at room temperature. Was sealed with a paraffin film and allowed to stand in a constant temperature bath at 40 ° C. After leaving still for 3 days, a pinhole having a diameter of about 1 mm was opened in the beaker film, and the plate was further left for 3 days. Thereafter, the film was removed and allowed to stand for 1 day. The obtained dried body was heat-treated in the atmosphere at 600 ° C. for 4 hours and further at 850 ° C. for 2 hours to obtain a siliceous porous body. Table 1 shows the type of porous body, pore size, porosity, proportion of spherical pores, gas permeability coefficient, thermal conductivity, bending strength, and thermal expansion coefficient.
チタニアゾル（石原産業（株）製、商品名：ＳＴＳ−０２）、ｐＨ調整剤としてアンモニア水、界面活性剤としてポリオキシエチレンアルキルエーテルを用いた。チタニアゾル１００ｇ（ｐＨ＝１）に対してアンモニア水をｐＨ＝３となるように添加し（０．７５ｍｌ程度）、さらに界面活性剤を０．２５ｍｌ添加した。この原料ゾルを２０℃に保ったウオーターバス内で静かに攪拌し、粘度が８００ｍＰａ・ｓになったところで、室温下、１リットルのビーカー中で機械的攪拌（ミキサー、１分間）を行い、ビーカーを、パラフィン製のフィルムで密閉して４０℃の恒温槽に静置させた。そのまま３日静置した後、ビーカーのフィルムに直径１ｍｍ程度のピンホールを１つ開け、さらに３日静置した。その後フィルムを外し、１日静置した。得られた乾燥体を、６００℃で４時間、さらに８５０℃で２時間、大気中で加熱処理し、チタニア質多孔体を得た。得られた多孔体の種類、気孔の大きさ、気孔率、球状気孔の占める割合、ガス透過係数、熱伝導率、曲げ強度、及び熱膨張係数を表１に示す。 Titania sol (manufactured by Ishihara Sangyo Co., Ltd., trade name: STS-02), aqueous ammonia as a pH adjuster, and polyoxyethylene alkyl ether as a surfactant were used. Ammonia water was added to 100 g of titania sol (pH = 1) so that pH = 3 (about 0.75 ml), and 0.25 ml of surfactant was further added. The raw material sol was gently stirred in a water bath maintained at 20 ° C. When the viscosity reached 800 mPa · s, mechanical stirring (mixer, 1 minute) was performed in a 1 liter beaker at room temperature. Was sealed with a paraffin film and allowed to stand in a constant temperature bath at 40 ° C. After leaving still for 3 days, a pinhole having a diameter of about 1 mm was opened in the beaker film, and the plate was further left for 3 days. Thereafter, the film was removed and allowed to stand for 1 day. The obtained dried product was heat-treated in the atmosphere at 600 ° C. for 4 hours and further at 850 ° C. for 2 hours to obtain a titania porous material. Table 1 shows the type of porous body, pore size, porosity, proportion of spherical pores, gas permeability coefficient, thermal conductivity, bending strength, and thermal expansion coefficient.
シリカゾル（日産化学（株）製、商品名：スノーテックスＳ）、ｐＨ調整剤として塩酸、界面活性剤としてラウリル硫酸エステルナトリウム塩を用いた。シリカゾル１００ｇ（ｐＨ＝１０）に対して塩酸をｐＨ＝６となるように添加し（１．２５ｍｌ程度）、さらに、界面活性剤を０．５ｍｌ添加した。一方で、蒸留水２０ｇにシリカ粉末３０ｇと界面活性剤のラウリル硫酸エステルナトリウム塩とポリアクリル酸アンモニウム塩を添加し、ｐＨ調整剤として塩酸をｐＨ＝６になるように添加した。この原料ゾルと原料スラリーをそれぞれ、２０℃に保ったウオーターバス内で静かに攪拌し、原料ゾルの粘度が１００００ｍＰａ・ｓになったところで、室温下、１リットルの円筒形状の型に移し、その中で機械的攪拌（ミキサー、１分間）を行い、型をパラフィン製のフィルムで密閉して４０℃の恒温槽に静置させた。そのまま２日静置した後、型から外し、調湿乾燥機にて、温度４０℃のまま、相対湿度を９０％から４０％まで２４時間で低下させて予備乾燥した。この予備乾燥体を１１０℃で１日乾燥した。得られた乾燥体を、８５０℃で２時間大気中で加熱処理し、シリカ質多孔体を得た。得られた多孔体の種類、気孔の大きさ、気孔率、球状気孔の占める割合、ガス透過係数、熱伝導率、曲げ強度、及び熱膨張係数を表２に示す。 Silica sol (manufactured by Nissan Chemical Co., Ltd., trade name: Snowtex S), hydrochloric acid as a pH adjuster, and sodium lauryl sulfate as a surfactant were used. To 100 g of silica sol (pH = 10), hydrochloric acid was added so that pH = 6 (about 1.25 ml), and 0.5 ml of surfactant was further added. On the other hand, 30 g of silica powder, sodium lauryl sulfate ester salt and ammonium polyacrylate were added to 20 g of distilled water, and hydrochloric acid was added as a pH adjuster so that pH = 6. The raw material sol and the raw material slurry were each gently stirred in a water bath maintained at 20 ° C., and when the viscosity of the raw material sol reached 10000 mPa · s, it was transferred to a 1 liter cylindrical mold at room temperature. The mixture was mechanically stirred (mixer, 1 minute), and the mold was sealed with a paraffin film and allowed to stand in a constant temperature bath at 40 ° C. After leaving it to stand for 2 days, it was removed from the mold, and pre-dried by reducing the relative humidity from 90% to 40% in 24 hours while maintaining the temperature at 40 ° C. with a humidity dryer. This pre-dried body was dried at 110 ° C. for 1 day. The obtained dried product was heat-treated at 850 ° C. for 2 hours in the air to obtain a siliceous porous material. Table 2 shows the type of porous body, pore size, porosity, proportion of spherical pores, gas permeability coefficient, thermal conductivity, bending strength, and thermal expansion coefficient.
シリカゾル（日産化学（株）製、商品名：スノーテックスＳ）、ｐＨ調整剤として塩酸、界面活性剤としてラウリル硫酸エステルナトリウム塩を用いた。シリカゾル１００ｇ（ｐＨ＝１０）に対して塩酸をｐＨ＝６となるように添加し（１．２５ｍｌ程度）、さらに、界面活性剤を０．５ｍｌ添加した。一方で、蒸留水５１ｇにアルミナ粉末７６ｇと界面活性剤のラウリル硫酸エステルナトリウム塩とポリアクリル酸アンモニウム塩を添加し、ｐＨ調整剤として塩酸をｐＨ＝６になるように添加した。この原料ゾルと原料スラリーをそれぞれ、２０℃に保ったウオーターバス内で静かに攪拌し、原料ゾルの粘度が１００００ｍＰａ・ｓになったところで、室温下、１リットルの円筒形状の型に移し、その中で機械的攪拌（ミキサー、１分間）を行い、型をパラフィン製のフィルムで密閉して４０℃の恒温槽に静置させた。そのまま２日静置した後、型から外し、調湿乾燥機にて、温度４０℃のまま、相対湿度を９０％から４０％まで２４時間で低下させて予備乾燥した。この予備乾燥体を１１０℃で１日乾燥した。得られた乾燥体を、１３００℃で２時間大気中で加熱処理し、ムライト質多孔体を得た。得られた多孔体の種類、気孔の大きさ、気孔率、球状気孔の占める割合、ガス透過係数、熱伝導率、曲げ強度、及び熱膨張係数を表２に示す。 Silica sol (manufactured by Nissan Chemical Co., Ltd., trade name: Snowtex S), hydrochloric acid as a pH adjuster, and sodium lauryl sulfate as a surfactant were used. To 100 g of silica sol (pH = 10), hydrochloric acid was added so that pH = 6 (about 1.25 ml), and 0.5 ml of surfactant was further added. On the other hand, 76 g of alumina powder, sodium lauryl sulfate ester and ammonium polyacrylate were added to 51 g of distilled water, and hydrochloric acid was added as a pH adjuster so that pH = 6. The raw material sol and the raw material slurry were each gently stirred in a water bath maintained at 20 ° C., and when the viscosity of the raw material sol reached 10000 mPa · s, it was transferred to a 1 liter cylindrical mold at room temperature. The mixture was mechanically stirred (mixer, 1 minute), and the mold was sealed with a paraffin film and allowed to stand in a constant temperature bath at 40 ° C. After leaving it to stand for 2 days, it was removed from the mold, and pre-dried by reducing the relative humidity from 90% to 40% in 24 hours while maintaining the temperature at 40 ° C. with a humidity dryer. This pre-dried body was dried at 110 ° C. for 1 day. The obtained dried body was heat-treated at 1300 ° C. for 2 hours in the air to obtain a mullite porous body. Table 2 shows the type of porous body, pore size, porosity, proportion of spherical pores, gas permeability coefficient, thermal conductivity, bending strength, and thermal expansion coefficient.
シリカゾル（日産化学（株）製、商品名：スノーテックスＳ）、ｐＨ調整剤として塩酸、界面活性剤としてラウリル硫酸エステルナトリウム塩を用いた。シリカゾル１００ｇ（ｐＨ＝１０）に対して塩酸をｐＨ＝６となるように添加し（１．２５ｍｌ程度）、さらに、界面活性剤を０．５ｍｌ添加した。一方で、蒸留水４８ｇにアルミナ粉末２６ｇと水酸化アルミニウム粉末２８ｇとタルク粉末５７ｇと、界面活性剤のラウリル硫酸エステルナトリウム塩とポリアクリル酸アンモニウム塩を添加し、ｐＨ調整剤として塩酸をｐＨ＝６になるように添加した。この原料ゾルと原料スラリーをそれぞれ、２０℃に保ったウオーターバス内で静かに攪拌し、原料ゾルの粘度が１０００ｍＰａ・ｓになったところで、室温下、１リットルの円筒形状の型に移し、その中で機械的攪拌（ミキサー、１分間）を行い、型をパラフィン製のフィルムで密閉して４０℃の恒温槽に静置させた。そのまま２日静置した後、型から外し、調湿乾燥機にて、温度４０℃のまま、相対湿度を９０％から４０％まで２４時間で低下させて予備乾燥した。この予備乾燥体を１１０℃で１日乾燥した。得られた乾燥体を、１４００℃で２時間大気中で加熱処理し、コージェライト質多孔体を得た。得られた多孔体の種類、気孔の大きさ、気孔率、球状気孔の占める割合、ガス透過係数、熱伝導率、曲げ強度、及び熱膨張係数を表２に示す。 Silica sol (manufactured by Nissan Chemical Co., Ltd., trade name: Snowtex S), hydrochloric acid as a pH adjuster, and sodium lauryl sulfate as a surfactant were used. To 100 g of silica sol (pH = 10), hydrochloric acid was added so that pH = 6 (about 1.25 ml), and 0.5 ml of surfactant was further added. On the other hand, 26 g of alumina powder, 28 g of aluminum hydroxide powder, 57 g of talc powder, surfactant lauryl sulfate sodium salt and ammonium polyacrylate were added to 48 g of distilled water, and hydrochloric acid was added at pH = 6 as a pH adjuster. It added so that it might become. The raw material sol and the raw material slurry were each gently stirred in a water bath maintained at 20 ° C., and when the viscosity of the raw material sol reached 1000 mPa · s, it was transferred to a 1 liter cylindrical mold at room temperature. The mixture was mechanically stirred (mixer, 1 minute), and the mold was sealed with a paraffin film and allowed to stand in a constant temperature bath at 40 ° C. After leaving it to stand for 2 days, it was removed from the mold, and pre-dried by reducing the relative humidity from 90% to 40% in 24 hours while maintaining the temperature at 40 ° C. with a humidity dryer. This pre-dried body was dried at 110 ° C. for 1 day. The obtained dried body was heat-treated at 1400 ° C. for 2 hours in the air to obtain a cordierite porous body. Table 2 shows the type of porous body, pore size, porosity, proportion of spherical pores, gas permeability coefficient, thermal conductivity, bending strength, and thermal expansion coefficient.
シリカゾル（日産化学（株）製、商品名：スノーテックスＳ）、ｐＨ調整剤として塩酸、界面活性剤としてラウリル硫酸エステルナトリウム塩を用いた。シリカゾル１００ｇ（ｐＨ＝１０）に対して塩酸をｐＨ＝６となるように添加し（１．２５ｍｌ程度）、さらに、界面活性剤を０．５ｍｌ添加した。一方で、蒸留水４０ｇに酸化マグネシウム粉末４０ｇと界面活性剤のラウリル硫酸エステルナトリウム塩とポリアクリル酸アンモニウム塩を添加し、ｐＨ調整剤として塩酸をｐＨ＝６になるように添加した。この原料ゾルと原料スラリーをそれぞれ、２０℃に保ったウオーターバス内で静かに攪拌し、原料ゾルの粘度が１００００ｍＰａ・ｓになったところで、室温下、１リットルの円筒形状の型に移し、その中で機械的攪拌（ミキサー、１分間）を行い、型をパラフィン製のフィルムで密閉して４０℃の恒温槽に静置させた。そのまま２日静置した後、型から外し、調湿乾燥機にて、温度４０℃のまま、相対湿度を９０％から４０％まで２４時間で低下させて予備乾燥した。この予備乾燥体を１１０℃で１日乾燥した。得られた乾燥体を、１５００℃で２時間大気中で加熱処理し、フォルステライト質多孔体を得た。得られた多孔体の種類、気孔の大きさ、気孔率、球状気孔の占める割合、ガス透過係数、熱伝導率、曲げ強度、及び熱膨張係数を表２に示す。 Silica sol (manufactured by Nissan Chemical Co., Ltd., trade name: Snowtex S), hydrochloric acid as a pH adjuster, and sodium lauryl sulfate as a surfactant were used. To 100 g of silica sol (pH = 10), hydrochloric acid was added so that pH = 6 (about 1.25 ml), and 0.5 ml of surfactant was further added. On the other hand, 40 g of magnesium oxide powder, sodium lauryl sulfate ester salt and polyacrylic acid ammonium salt were added to 40 g of distilled water, and hydrochloric acid was added as a pH adjuster so that pH = 6. The raw material sol and the raw material slurry were each gently stirred in a water bath maintained at 20 ° C., and when the viscosity of the raw material sol reached 10000 mPa · s, it was transferred to a 1 liter cylindrical mold at room temperature. The mixture was mechanically stirred (mixer, 1 minute), and the mold was sealed with a paraffin film and allowed to stand in a constant temperature bath at 40 ° C. After leaving it to stand for 2 days, it was removed from the mold, and pre-dried by reducing the relative humidity from 90% to 40% in 24 hours while maintaining the temperature at 40 ° C. with a humidity dryer. This pre-dried body was dried at 110 ° C. for 1 day. The obtained dried body was heat-treated at 1500 ° C. for 2 hours in the air to obtain a forsterite porous body. Table 2 shows the type of porous body, pore size, porosity, proportion of spherical pores, gas permeability coefficient, thermal conductivity, bending strength, and thermal expansion coefficient.
チタニアゾル（石原産業（株）製、商品名：ＳＴＳ−０２）、ｐＨ調整剤としてアンモニア水、界面活性剤としてラウリル硫酸エステルナトリウム塩を用いた。シリカゾル１００ｇ（ｐＨ＝１）に対してアンモニア水をｐＨ＝３となるように添加し（０．７５ｍｌ程度）、さらに、界面活性剤を０．２５ｍｌ添加した。一方で、蒸留水２６ｇにアルミナ粉末３８ｇと界面活性剤のラウリル硫酸エステルナトリウム塩とポリアクリル酸アンモニウム塩を添加し、ｐＨ調整剤として塩酸をｐＨ＝６になるように添加した。この原料ゾルと原料スラリーをそれぞれ、２０℃に保ったウオーターバス内で静かに攪拌し、原料ゾルの粘度が１０００ｍＰａ・ｓになったところで、室温下、１リットルの円筒形状の型に移し、その中で機械的攪拌（ミキサー、１分間）を行い、型をパラフィン製のフィルムで密閉して４０℃の恒温槽に静置させた。そのまま２日静置した後、型から外し、調湿乾燥機にて、温度４０℃のまま、相対湿度を９０％から４０％まで２４時間で低下させて予備乾燥した。この予備乾燥体を１１０℃で１日乾燥した。得られた乾燥体を、１５５０℃で２時間大気中で加熱処理し、アルミニウムチタネート質多孔体を得た。得られた多孔体の種類、気孔の大きさ、気孔率、球状気孔の占める割合、ガス透過係数、熱伝導率、曲げ強度、及び熱膨張係数を表２に示す。
（比較例１）
シリカゾル（日産化学（株）製、商品名：スノーテックスＳ）、ｐＨ調整剤として塩酸、界面活性剤としてラウリル硫酸エステルナトリウム塩を用いた。シリカゾル１００ｇ（ｐＨ＝１０）に対して塩酸をｐＨ＝６となるように添加し（１．２５ｍｌ程度）、さらに、界面活性剤を０．５ｍｌ添加した。この調製ゾルを２０℃に保ったウオーターバス内で静かに攪拌し、粘度が５０ｍＰａ・ｓになったところで、室温下、１リットルのビーカー中で機械的攪拌（ミキサー、１分間）を行い、ビーカーを、パラフィン製のフィルムで密閉して４０℃の恒温槽に静置させた。そのまま３日静置した後、ビーカーのフィルムに直径１ｍｍ程度のピンホールを１つ開け、さらに３日静置した。その後フィルムを外し、１日静置した。得られた乾燥体を、６００℃で４時間、さらに８５０℃で２時間、大気中で加熱処理し、シリカ質多孔体を得た。得られた多孔体の種類、気孔の大きさ、気孔率、球状気孔の占める割合、ガス透過係数、熱伝導率、曲げ強度、及び熱膨張係数を表１に示す。
（比較例２）
シリカゾル（日産化学（株）製、商品名：スノーテックスＳ）、ｐＨ調整剤として塩酸、界面活性剤としてラウリル硫酸エステルナトリウム塩を用いた。シリカゾル１００ｇ（ｐＨ＝１０）に対して塩酸をｐＨ＝６となるように添加し（１．２５ｍｌ程度）、さらに、界面活性剤を０．５ｍｌ添加した。この原料ゾルを２０℃に保ったウオーターバス内で静かに攪拌し、粘度が３００００ｍＰａ・ｓになったところで、室温下、１リットルのビーカー中で機械的攪拌（ミキサー、１分間）を行い、ビーカーを、パラフィン製のフィルムで密閉して４０℃の恒温槽に静置させた。そのまま３日静置した後、ビーカーのフィルムに直径１ｍｍ程度のピンホールを１つ開け、さらに３日静置した。その後フィルムを外し、１日静置した。得られた乾燥体を、６００℃で４時間、さらに８５０℃で２時間、大気中で加熱処理し、シリカ質多孔体を得た。得られた多孔体の種類、気孔の大きさ、気孔率、球状気孔の占める割合、ガス透過係数、熱伝導率、曲げ強度、及び熱膨張係数を表１に示す。
実施例及び比較例で得られた無機質多孔体に対して、気孔構造を走査型電子顕微鏡で観察したところ、図１に示すように、実施例１で得られた多孔体は、細い骨格からなる三次元の網目構造を有するシリカ質多孔体であった。図２、３に示すように、実施例２、３で得られた多孔体は、スポンジ構造で、隣り合う気孔が連結したシリカ質多孔体であった。図４に示すように、実施例４で得られた多孔体は、スポンジ構造で、隣り合う気孔が比較的連結していないシリカ質多孔体であった。図５に示すように、実施例５で得られた多孔体は、スポンジ構造で、それぞれの気孔が独立したシリカ質多孔体であった。実施例６で得られた多孔体はスポンジ構造で隣り合う気孔が連結したチタニア質多孔体であった。図７に示すように、実施例７で得られた多孔体は、スポンジ構造で、それぞれの気孔が独立したシリカ質多孔体であった。実施例８で得られた多孔体は、スポンジ構造で、それぞれの気孔が独立したムライト質多孔体であった。図８に示すように、実施例９で得られた多孔体は、比較的細い骨格からなる三次元の網目構造を有するコージェライト質多孔体であった。実施例１０で得られた多孔体は、スポンジ構造で、それぞれの気孔が独立したフォルステライト質多孔体であった。実施例１１で得られた多孔体は、比較的細い骨格からなる三次元の網目構造を有するアルミニウムチタネート質多孔体であった。図９に示すように、比較例１で得られた多孔体は、細い骨格からなる三次元の網目構造を有するシリカ質多孔体であったが、一部は泡が消失した緻密な構造となった。比較例２で得られた多孔体は、うまく気孔が形成されずに、緻密な部分が多く、評価に値しなかった。
実施例及び比較例で得られた無機質多孔体の寸法と重量を測定してそれぞれの嵩密度を算出した。真密度をシリカ２．０ｇ／ｃｍ３、チタニア３．９ｇ／ｃｍ３、コージェライト２．５ｇ／ｃｍ３、ムライト３．１ｇ／ｃｍ３、フォルステライト３．２ｇ／ｃｍ３、アルミニウムチタネート３．５ｇ／ｃｍ３として、下記式（１）から気孔率を算出した。ガス透過係数は、ダルシーの法則（ＤＡＲＣＹ’Ｓ ＬＡＷ）に従い、下記式（２）から算出した。熱伝導率は定常法により測定し、曲げ強度及び熱膨張係数はそれぞれ、ＪＩＳ Ｒ１６０１、Ｒ１６１８に準拠した方法で測定した。その結果を表１に示す。表１から、本発明の第１の無機質多孔体は、ガスを透過させた場合、圧力損失が低い上に、構造材料としても適用し得る、熱膨張率及び機械的強度を備えており、また、本発明の第２の無機質多孔体は、熱伝導率が低い上に、構造材料としても適用し得る、熱膨張率及び機械的強度を備えていることがわかる。
(Comparative Example 1)
Silica sol (manufactured by Nissan Chemical Co., Ltd., trade name: Snowtex S), hydrochloric acid as a pH adjuster, and sodium lauryl sulfate as a surfactant were used. To 100 g of silica sol (pH = 10), hydrochloric acid was added so that pH = 6 (about 1.25 ml), and 0.5 ml of surfactant was further added. The prepared sol was gently stirred in a water bath maintained at 20 ° C. When the viscosity reached 50 mPa · s, mechanical stirring (mixer, 1 minute) was performed in a 1 liter beaker at room temperature. Was sealed with a paraffin film and allowed to stand in a constant temperature bath at 40 ° C. After leaving still for 3 days, a pinhole having a diameter of about 1 mm was opened in the beaker film, and the plate was further left for 3 days. Thereafter, the film was removed and allowed to stand for 1 day. The obtained dried body was heat-treated in the atmosphere at 600 ° C. for 4 hours and further at 850 ° C. for 2 hours to obtain a siliceous porous body. Table 1 shows the type of porous body, pore size, porosity, proportion of spherical pores, gas permeability coefficient, thermal conductivity, bending strength, and thermal expansion coefficient.
(Comparative Example 2)
Silica sol (manufactured by Nissan Chemical Co., Ltd., trade name: Snowtex S), hydrochloric acid as a pH adjuster, and sodium lauryl sulfate as a surfactant were used. To 100 g of silica sol (pH = 10), hydrochloric acid was added so that pH = 6 (about 1.25 ml), and 0.5 ml of surfactant was further added. The raw material sol was gently stirred in a water bath maintained at 20 ° C. When the viscosity reached 30000 mPa · s, mechanical stirring (mixer, 1 minute) was performed in a 1 liter beaker at room temperature. Was sealed with a paraffin film and allowed to stand in a constant temperature bath at 40 ° C. After leaving still for 3 days, a pinhole having a diameter of about 1 mm was opened in the beaker film, and the plate was further left for 3 days. Thereafter, the film was removed and allowed to stand for 1 day. The obtained dried body was heat-treated in the atmosphere at 600 ° C. for 4 hours and further at 850 ° C. for 2 hours to obtain a siliceous porous body. Table 1 shows the type of porous body, pore size, porosity, proportion of spherical pores, gas permeability coefficient, thermal conductivity, bending strength, and thermal expansion coefficient.
When the pore structure was observed with a scanning electron microscope for the inorganic porous bodies obtained in Examples and Comparative Examples, as shown in FIG. 1, the porous body obtained in Example 1 was composed of a thin skeleton. It was a siliceous porous material having a three-dimensional network structure. As shown in FIGS. 2 and 3, the porous body obtained in Examples 2 and 3 was a siliceous porous body having a sponge structure in which adjacent pores were connected. As shown in FIG. 4, the porous body obtained in Example 4 was a siliceous porous body having a sponge structure in which adjacent pores were not relatively connected. As shown in FIG. 5, the porous body obtained in Example 5 was a siliceous porous body having a sponge structure and independent pores. The porous body obtained in Example 6 was a titania porous body having a sponge structure in which adjacent pores were connected. As shown in FIG. 7, the porous body obtained in Example 7 was a siliceous porous body having a sponge structure and independent pores. The porous body obtained in Example 8 was a mullite porous body having a sponge structure and independent pores. As shown in FIG. 8, the porous body obtained in Example 9 was a cordierite porous body having a three-dimensional network structure composed of a relatively thin skeleton. The porous body obtained in Example 10 was a forsterite porous body having a sponge structure and independent pores. The porous body obtained in Example 11 was an aluminum titanate porous body having a three-dimensional network structure composed of a relatively thin skeleton. As shown in FIG. 9, the porous body obtained in Comparative Example 1 was a siliceous porous body having a three-dimensional network structure composed of a thin skeleton, but a part of the porous body had a dense structure in which bubbles disappeared. It was. The porous body obtained in Comparative Example 2 was not worthy of evaluation because pores were not formed well and there were many dense portions.
The dimensions and weights of the inorganic porous bodies obtained in Examples and Comparative Examples were measured to calculate the respective bulk densities. True density of silica 2.0 g / cm 3 , titania 3.9 g / cm 3 , cordierite 2.5 g / cm 3 , mullite 3.1 g / cm 3 , forsterite 3.2 g / cm 3 , aluminum titanate 3.5 g The porosity was calculated from the following formula (1) as / cm 3 . The gas permeability coefficient was calculated from the following formula (2) according to Darcy's law (DARCY'S LAW). The thermal conductivity was measured by a steady method, and the bending strength and the thermal expansion coefficient were measured by methods based on JIS R1601 and R1618, respectively. The results are shown in Table 1. From Table 1, the first inorganic porous body of the present invention has a thermal expansion coefficient and mechanical strength that can be applied as a structural material in addition to low pressure loss when gas is permeated. It can be seen that the second inorganic porous body of the present invention has a low thermal conductivity and a thermal expansion coefficient and mechanical strength that can also be applied as a structural material.
本発明の無機質多孔体及びその製造方法は、フィルター等の各種分離装置を用いる分野、断熱材等の各種工業用材料を用いる分野で好適に用いられる。 The inorganic porous material and the method for producing the same of the present invention are suitably used in the field of using various separation devices such as filters and the field of using various industrial materials such as heat insulating materials.
Claims (15)
前記気孔構造を形成する前記気孔の大きさが、５μｍ〜２ｍｍであり、気孔率が６０％以上であり、かつガス透過係数が１×１０−１１ｍ２以上であることを特徴とする無機質多孔体。An inorganic porous body having a pore structure (three-dimensional network structure and / or sponge-like structure) composed of a large number of continuous pores, at least a part of which is spherical,
An inorganic porous material characterized in that the pores forming the pore structure have a pore size of 5 μm to 2 mm, a porosity of 60% or more, and a gas permeability coefficient of 1 × 10 −11 m 2 or more. body.
得られた前記原料ゾルを機械的に攪拌して、気泡が導入されたゾル多孔体を形成し、
得られた前記ゾル多孔体を、必要に応じ所定温度で加熱して、ゲル化させ、ゲル多孔体を形成し、
得られた前記ゲル多孔体を乾燥して、乾燥ゲル多孔体を形成し、
得られた前記乾燥ゲル多孔体を熱処理することを特徴とする無機質多孔体の製造方法。The metal oxide sol and / or the metal hydroxide sol, the first surfactant, and the first pH adjuster are subjected to pH and temperature conditions such that the viscosity is 100 to 20000 mPa · s. Mix to prepare a raw material sol having a predetermined gel time,
The obtained raw material sol is mechanically stirred to form a sol porous body into which bubbles are introduced,
The obtained sol porous body is heated at a predetermined temperature as necessary to be gelled to form a gel porous body,
The gel porous body obtained is dried to form a dry gel porous body,
A method for producing an inorganic porous body, comprising heat-treating the obtained dried gel porous body.
前記ゲル多孔体を、温度と湿度を保持したまま静置して熟成して、熟成ゲル多孔体を形成し、得られた前記熟成ゲル多孔体を、温度を保持したまま、湿度を下げて予備乾燥して、予備乾燥ゲル多孔体を形成し、前記予備乾燥ゲル多孔体を乾燥して、前記乾燥ゲル多孔体を形成し、得られた前記乾燥ゲル多孔体を熱処理する請求項７に記載の無機質多孔体の製造方法。When the gel porous body is dried to form the dry gel porous body and the obtained dried gel porous body is heat-treated,
The gel porous body is left standing and aging while maintaining the temperature and humidity to form an aged gel porous body, and the resulting aged gel porous body is preliminarily reduced in humidity while maintaining the temperature. The dried gel porous body is dried to form a pre-dried gel porous body, the pre-dried gel porous body is dried to form the dry gel porous body, and the obtained dry gel porous body is heat-treated. A method for producing an inorganic porous material.
他方で、金属酸化物、金属水酸化物及び金属炭酸塩からなる群から選ばれる少なくとも一種の原料粉末を含む原料粉末調製物を調製し、
得られた前記原料ゾルと前記原料粉末調製物とを混合し、次いで、機械的に攪拌して、気泡が導入された粉末含有ゾル多孔体を形成し、
得られた前記粉末含有ゾル多孔体を、必要に応じ所定温度で加熱して、ゲル化させ、粉末含有ゲル多孔体を形成し、
得られた前記粉末含有ゲル多孔体を乾燥して、乾燥粉末含有ゲル多孔体を形成し、
得られた前記乾燥粉末含有ゲル多孔体を熱処理することを特徴とする無機質多孔体の製造方法。On the other hand, the metal oxide sol and / or metal hydroxide sol, the second surfactant, and the second pH adjuster are adjusted to a pH and temperature such that the viscosity is 100 to 20000 mPa · s. To prepare a raw material sol having a predetermined gelation time,
On the other hand, preparing a raw material powder preparation containing at least one raw material powder selected from the group consisting of metal oxides, metal hydroxides and metal carbonates,
The obtained raw material sol and the raw material powder preparation are mixed, and then mechanically stirred to form a powder-containing sol porous body into which bubbles are introduced,
The obtained powder-containing sol porous body is heated at a predetermined temperature as necessary to be gelled to form a powder-containing gel porous body,
The obtained powder-containing gel porous body is dried to form a dry powder-containing gel porous body,
A method for producing an inorganic porous body, comprising heat-treating the obtained dry powder-containing gel porous body.
前記粉末含有ゲル多孔体を、温度及び湿度を保持したまま静置して熟成して、熟成粉末含有ゲル多孔体を形成し、得られた前記熟成粉末含有ゲル多孔体を、温度を保持したまま、湿度を下げて予備乾燥して、予備乾燥粉末含有ゲル多孔体を形成し、前記予備乾燥粉末含有ゲル多孔体を乾燥して、前記乾燥粉末含有ゲル多孔体を形成し、得られた前記乾燥粉末含有ゲル多孔体を熱処理する請求項１１又は１２に記載の無機質多孔体の製造方法。When the powder-containing gel porous body is dried to form the dry powder-containing gel porous body, and when the obtained dry powder-containing gel porous body is heat-treated,
The powder-containing gel porous body is left standing and aging while maintaining temperature and humidity to form an aged powder-containing gel porous body, and the obtained aged powder-containing gel porous body is maintained at a temperature. The pre-dried powder-containing gel porous body is formed by reducing the humidity and pre-dried, and the pre-dried powder-containing gel porous body is dried to form the dry powder-containing gel porous body. The manufacturing method of the inorganic porous body of Claim 11 or 12 which heat-processes a powder containing gel porous body.
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