JP2005104825A - Fine silver oxide powder and its manufacturing method - Google Patents
Fine silver oxide powder and its manufacturing method Download PDFInfo
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- JP2005104825A JP2005104825A JP2004244849A JP2004244849A JP2005104825A JP 2005104825 A JP2005104825 A JP 2005104825A JP 2004244849 A JP2004244849 A JP 2004244849A JP 2004244849 A JP2004244849 A JP 2004244849A JP 2005104825 A JP2005104825 A JP 2005104825A
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- NDVLTYZPCACLMA-UHFFFAOYSA-N silver oxide Chemical compound [O-2].[Ag+].[Ag+] NDVLTYZPCACLMA-UHFFFAOYSA-N 0.000 title claims abstract description 142
- 229910001923 silver oxide Inorganic materials 0.000 title claims abstract description 73
- 239000000843 powder Substances 0.000 title claims abstract description 67
- 239000010946 fine silver Substances 0.000 title claims abstract 3
- 238000004519 manufacturing process Methods 0.000 title claims description 11
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 75
- 239000007788 liquid Substances 0.000 claims abstract description 54
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims abstract description 42
- 238000006386 neutralization reaction Methods 0.000 claims abstract description 38
- 239000002245 particle Substances 0.000 claims abstract description 38
- 239000002270 dispersing agent Substances 0.000 claims abstract description 22
- 238000000034 method Methods 0.000 claims abstract description 22
- GGCZERPQGJTIQP-UHFFFAOYSA-N sodium;9,10-dioxoanthracene-2-sulfonic acid Chemical compound [Na+].C1=CC=C2C(=O)C3=CC(S(=O)(=O)O)=CC=C3C(=O)C2=C1 GGCZERPQGJTIQP-UHFFFAOYSA-N 0.000 claims abstract description 22
- 239000000084 colloidal system Substances 0.000 claims abstract description 21
- 230000001681 protective effect Effects 0.000 claims abstract description 21
- 239000011164 primary particle Substances 0.000 claims abstract description 19
- 239000011163 secondary particle Substances 0.000 claims abstract description 16
- 239000003960 organic solvent Substances 0.000 claims abstract description 13
- GCLGEJMYGQKIIW-UHFFFAOYSA-H sodium hexametaphosphate Chemical compound [Na]OP1(=O)OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])O1 GCLGEJMYGQKIIW-UHFFFAOYSA-H 0.000 claims abstract description 12
- 235000019982 sodium hexametaphosphate Nutrition 0.000 claims abstract description 12
- 239000001577 tetrasodium phosphonato phosphate Substances 0.000 claims abstract description 12
- 238000001035 drying Methods 0.000 claims abstract description 9
- 238000002441 X-ray diffraction Methods 0.000 claims abstract description 7
- 238000001238 wet grinding Methods 0.000 claims abstract description 7
- 238000004438 BET method Methods 0.000 claims abstract description 6
- 238000001914 filtration Methods 0.000 claims abstract description 6
- 238000005406 washing Methods 0.000 claims abstract description 6
- 239000007864 aqueous solution Substances 0.000 claims description 44
- 239000002609 medium Substances 0.000 claims description 31
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 12
- 108010010803 Gelatin Proteins 0.000 claims description 8
- 229920000159 gelatin Polymers 0.000 claims description 8
- 239000008273 gelatin Substances 0.000 claims description 8
- 235000019322 gelatine Nutrition 0.000 claims description 8
- 235000011852 gelatine desserts Nutrition 0.000 claims description 8
- 239000006185 dispersion Substances 0.000 claims description 7
- 230000003472 neutralizing effect Effects 0.000 claims description 7
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 5
- 238000005259 measurement Methods 0.000 claims description 5
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 5
- 239000002244 precipitate Substances 0.000 claims description 5
- 150000001299 aldehydes Chemical class 0.000 claims description 4
- 150000002148 esters Chemical class 0.000 claims description 4
- 239000010419 fine particle Substances 0.000 claims description 4
- 230000008014 freezing Effects 0.000 claims description 4
- 238000007710 freezing Methods 0.000 claims description 4
- 150000002576 ketones Chemical class 0.000 claims description 4
- 239000004375 Dextrin Substances 0.000 claims description 3
- 229920001353 Dextrin Polymers 0.000 claims description 3
- 229920000084 Gum arabic Polymers 0.000 claims description 3
- 241000978776 Senegalia senegal Species 0.000 claims description 3
- 239000000205 acacia gum Substances 0.000 claims description 3
- 235000010489 acacia gum Nutrition 0.000 claims description 3
- 150000001298 alcohols Chemical class 0.000 claims description 3
- 235000019425 dextrin Nutrition 0.000 claims description 3
- 239000002612 dispersion medium Substances 0.000 claims description 3
- 235000019422 polyvinyl alcohol Nutrition 0.000 claims description 3
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 abstract description 33
- 229910052709 silver Inorganic materials 0.000 abstract description 28
- 239000004332 silver Substances 0.000 abstract description 28
- 239000000945 filler Substances 0.000 abstract description 6
- 239000013049 sediment Substances 0.000 abstract 2
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 description 34
- 229910001961 silver nitrate Inorganic materials 0.000 description 17
- 239000000243 solution Substances 0.000 description 13
- 238000006243 chemical reaction Methods 0.000 description 11
- 239000012266 salt solution Substances 0.000 description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 8
- 238000010298 pulverizing process Methods 0.000 description 8
- 238000000926 separation method Methods 0.000 description 8
- 239000011882 ultra-fine particle Substances 0.000 description 8
- 229920002472 Starch Polymers 0.000 description 7
- 239000008107 starch Substances 0.000 description 7
- 235000019698 starch Nutrition 0.000 description 7
- 239000000463 material Substances 0.000 description 6
- 239000000047 product Substances 0.000 description 6
- 239000000758 substrate Substances 0.000 description 6
- 238000003917 TEM image Methods 0.000 description 5
- 239000003513 alkali Substances 0.000 description 5
- 239000012670 alkaline solution Substances 0.000 description 5
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 3
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 3
- 239000012298 atmosphere Substances 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 238000001291 vacuum drying Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 239000003638 chemical reducing agent Substances 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- 238000002076 thermal analysis method Methods 0.000 description 2
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Natural products OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000001154 acute effect Effects 0.000 description 1
- 229960005070 ascorbic acid Drugs 0.000 description 1
- 235000010323 ascorbic acid Nutrition 0.000 description 1
- 239000011668 ascorbic acid Substances 0.000 description 1
- 239000011805 ball Substances 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000000740 bleeding effect Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000012776 electronic material Substances 0.000 description 1
- 238000010828 elution Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000009775 high-speed stirring Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- TYQCGQRIZGCHNB-JLAZNSOCSA-N l-ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(O)=C(O)C1=O TYQCGQRIZGCHNB-JLAZNSOCSA-N 0.000 description 1
- 238000009766 low-temperature sintering Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- OTCVAHKKMMUFAY-UHFFFAOYSA-N oxosilver Chemical class [Ag]=O OTCVAHKKMMUFAY-UHFFFAOYSA-N 0.000 description 1
- 238000000634 powder X-ray diffraction Methods 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000005070 ripening Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000009834 vaporization Methods 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
- -1 wet grinding Substances 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Abstract
Description
本発明は、とくに導電ペースト用のフィラーに適した微粒子酸化銀粉末に関する。 The present invention relates to a fine particle silver oxide powder particularly suitable as a filler for a conductive paste.
最近の半導体分野の高集積化と高速化に伴って、基板配線の微細化と多層化が進んでいる。それに伴って導電ペースト中に含有させる配線材料としての銀の超微粒子化が要求されている。またこの超微粒子化により、低温焼結ペーストへの応用、インクジェットでの配線印刷用途などに期待されている。 With recent high integration and high speed in the semiconductor field, substrate wiring is becoming finer and multilayered. Accordingly, ultrafine silver particles are required as a wiring material to be contained in the conductive paste. In addition, the ultrafine particles are expected to be applied to low-temperature sintering pastes and wiring printing with inkjets.
従来より、銀の超微粒子の製造は、主として蒸発法で行われていたので、大きなエネルギーを必要とすることと、生産速度が遅いことなどから、製造コストが高くならざるを得なかった。 Conventionally, the production of ultrafine silver particles has been mainly carried out by the evaporation method, so that a large amount of energy is required and the production speed is slow, and thus the production cost must be increased.
銀に代えて或いは銀と併用して酸化銀を配線材料に使用することも提案されている。例えば非特許文献１には、導電ペースト用のフィラーとして酸化銀を使用すると共に、該ペースト中に適切な還元材を配合したペーストが提案されており、このペーストの加熱時に該酸化銀を銀に還元すると同時に粒子を融着して導体を形成するとされている。また、特許文献１には、有機溶媒に１０ｎｍ以下の銀含有超微粒子を独立分散させた分散液が記載され、この銀含有超微粒子は銀若しくは酸化銀またはその混合物であってもよいとされている。
銀に代えて或いは銀と併用して酸化銀を配線材料に使用できれば、高コストであった銀超微粒子を配線材料とする場合に比べて、安価に銀配線が達成できる可能性があるが、そのためには、超微粒子酸化銀を工業的有利に且つ安定して製造できることが肝要である。本発明はこの要求を満たすことを課題としたものであり、これによって、安価で高品質の超微粒子酸化銀粉末を提供しようとするものである。 If silver oxide can be used as a wiring material instead of silver or in combination with silver, there is a possibility that silver wiring can be achieved at a lower cost compared to the case of using silver ultrafine particles, which was expensive, as a wiring material. For this purpose, it is important that ultrafine silver oxide can be produced industrially advantageously and stably. An object of the present invention is to satisfy this requirement, and thereby to provide an inexpensive and high-quality ultrafine silver oxide powder.
前記の課題を解決する超微粒子酸化銀粉末として、本発明によれば、ＢＥＴ法による比表面積が１.０〜２５.０ｍ2／g 、１次粒子の平均粒径が１〜５０ｎｍ、２次粒子の平均粒径が１〜１０００ｎｍの酸化銀粉末を提供する。この超微粒子酸化銀粉末は、分散媒として０.２重量％ヘキサメタリン酸ナトリウム水溶液を使用したレーザー方式による粒度分布測定において、粒径が１〜１０００ｎｍの範囲内にあり且つ分布のピークが１つである。また、Ｘ線回折法による（１１１）面の回折ピークの半値幅が０.２５°以上である。 As an ultrafine silver oxide powder that solves the above problems, according to the present invention, the specific surface area by the BET method is 1.0 to 25.0 m 2 / g, the average particle size of primary particles is 1 to 50 nm, A silver oxide powder having an average particle diameter of 1 to 1000 nm is provided. This ultrafine silver oxide powder has a particle size in the range of 1 to 1000 nm and a single distribution peak in a laser particle size distribution measurement using a 0.2 wt% aqueous sodium hexametaphosphate solution as a dispersion medium. is there. Further, the half width of the diffraction peak of the (111) plane by the X-ray diffraction method is 0.25 ° or more.
本発明に従う超微粒子酸化銀粉末は、水酸化ナトリウムまたは水酸化カリウムの１種または２種を合計で０. ５モル／Ｌ以下の量で含む水溶液を中和用液媒体とし、この液媒体に対して、銀塩を６. ０モル／Ｌ以下の量で含む水溶液と、水酸化ナトリウムまたは水酸化カリウムの少なくとも１種の水溶液とを同時に添加して中和反応を行わせること、該中和反応の間の液のｐＨを１２±１.５の範囲に維持すること、そして、得られた中和殿物をろ過、水洗したあと乾燥することによって製造することができる。 The ultrafine silver oxide powder according to the present invention comprises an aqueous solution containing one or two kinds of sodium hydroxide or potassium hydroxide in a total amount of 0.5 mol / L or less as a neutralizing liquid medium. On the other hand, an aqueous solution containing a silver salt in an amount of 6.0 mol / L or less and at least one aqueous solution of sodium hydroxide or potassium hydroxide are simultaneously added to cause a neutralization reaction, It can be prepared by maintaining the pH of the liquid during the reaction in the range of 12 ± 1.5, and filtering, washing, and drying the resulting neutralized residue.
そのさい、この中和反応を保護コロイドおよび／または分散剤の共存下で行わせるのが好ましく、その反応温度は、使用した保護コロイドおよび／または分散剤の凝固点以上１１０℃以下の温度に維持するのがよい。この場合も、中和反応の間の液のｐＨは１２.０±１.５の範囲に維持する。また、生成した中和殿物は液からろ別したあと、所望により分散剤または有機溶媒中に再分散して湿式粉砕する。 At this time, the neutralization reaction is preferably carried out in the presence of a protective colloid and / or a dispersant, and the reaction temperature is maintained at a temperature not lower than the freezing point of the used protective colloid and / or dispersant and not higher than 110 ° C. It is good. Again, the pH of the solution during the neutralization reaction is maintained in the range of 12.0 ± 1.5. Further, the produced neutralized precipitate is filtered from the liquid, then re-dispersed in a dispersant or an organic solvent, if desired, and wet pulverized.
使用する保護コロイドはゼラチン、アラビアゴム、デキストリン、またはポリビニルアルコールの少なくとも１種、分散剤はヘキサメタリン酸ナトリウムまたはエチレングリコールの少なくとも１種、そして、有機溶媒はアルコール類、エステル類、ケトン類、アルデヒド類の少なくとも１種であることができる。 The protective colloid used is at least one of gelatin, gum arabic, dextrin, or polyvinyl alcohol, the dispersant is at least one of sodium hexametaphosphate or ethylene glycol, and the organic solvent is alcohols, esters, ketones, aldehydes At least one of the following.
本発明に従う超微粒子酸化銀粉末は酸化銀から銀への還元温度が低いので、銀系の導電回路を形成するための導電ペーストや分散液のフィラーとして好適である。また本発明に従う方法によれば、本発明の超微粒子酸化銀粉末を安価に製造できる。 Since the ultrafine silver oxide powder according to the present invention has a low reduction temperature from silver oxide to silver, it is suitable as a conductive paste or dispersion filler for forming a silver-based conductive circuit. Moreover, according to the method according to the present invention, the ultrafine silver oxide powder of the present invention can be produced at low cost.
各種基板の表面や内部あるいは外部に導電回路や電極を形成する手段として銀粉をフイラーとした導電ペーストを使用する場合、基板表面や内部等に導電ペーストを塗布または充填した状態で基板と共に適切な加熱処理を行うと、ペースト中の揮発性媒体の気化や有機物質の分解によってこれらが除去され、残存する銀粒子同士が焼結して通電可能な回路が形成される。銀粉に代えて酸化銀粉末をフイラーとして使用し、さらにアスコルビン酸等の還元剤をペースト中に共存させておくと、前記の如く熱処理の過程で酸化銀粉末が銀に還元され且つそれが焼結し通電可能な回路が形成される。 When using conductive paste with silver powder filler as a means to form conductive circuits and electrodes on the surface, inside or outside of various substrates, heat appropriately together with the substrate with the conductive paste applied or filled on the substrate surface or inside. When the treatment is performed, these are removed by vaporization of the volatile medium in the paste or decomposition of the organic substance, and the remaining silver particles are sintered to form a circuit that can be energized. If silver oxide powder is used as a filler instead of silver powder, and a reducing agent such as ascorbic acid coexists in the paste, the silver oxide powder is reduced to silver during the heat treatment as described above, and it is sintered. A circuit that can be energized is formed.
この場合、使用する酸化銀は、微粉であればあるほど微細な配線回路を形成するのに適するが、その比表面積と一次粒径が適正であると還元温度を下げることができる。すなわち、後記の実施例に示すように、一次粒径が５０ｎｍ以下、好ましくは３０ｎｍ以下で比表面積が１ｍ2／g 以上、好ましくは２ｍ2／g 以上の超微粒子酸化銀粉末の場合には、この酸化銀を銀に還元できる還元温度は４００℃以下、好ましくは３８０℃以下にまで低下させることができる。 In this case, the finer the silver oxide used, the more suitable for forming a fine wiring circuit, but the reduction temperature can be lowered if the specific surface area and primary particle size are appropriate. That is, as shown in the examples below, in the case of ultrafine silver oxide powder having a primary particle size of 50 nm or less, preferably 30 nm or less and a specific surface area of 1 m 2 / g or more, preferably 2 m 2 / g or more, The reduction temperature at which this silver oxide can be reduced to silver can be lowered to 400 ° C. or lower, preferably 380 ° C. or lower.
ここで、比表面積はＢＥＴ法で測定される比表面積である。また、一次粒径はそれ以上単分散できない最小単位の粒子（一次粒子）の径である。一次粒子が互いに寄り集まって群をなしている（凝集している）場合に、その一つの群を二次粒子と言うが、二次粒子は分散の仕方によっては一次粒子に分散させることが可能である。本発明に従う超微粒子酸化銀粉末は二次粒子の平均粒径が１〜１０００ｎｍの範囲にある。 Here, the specific surface area is a specific surface area measured by the BET method. The primary particle size is the diameter of the smallest unit particle (primary particle) that cannot be monodispersed any more. When primary particles are gathered together to form a group (aggregate), one group is called secondary particles. Depending on the dispersion method, secondary particles can be dispersed into primary particles. It is. The ultrafine silver oxide powder according to the present invention has an average secondary particle diameter in the range of 1 to 1000 nm.
本発明に従う超微粒子酸化銀粉末はその粒度分布を測定した場合、二次粒子が存在していても、一つのピークを有する。すなわち、分散媒として０.２重量％ヘキサメタリン酸ナトリウム水溶液を使用したレーザー方式による粒度分布測定において、粒径が１〜１０００ｎｍの範囲内にあり且つ分布のピークが１つである。このことは、乾粉としては二次粒子の状態で存在していても、一次粒子に簡単に分散されることを意味しており、一次粒子に分散された状態では分布幅の狭い粒径の揃った超微粒子酸化銀粉末であることを意味している。 When the particle size distribution of the ultrafine silver oxide powder according to the present invention is measured, it has one peak even if secondary particles are present. That is, in the particle size distribution measurement by a laser method using a 0.2 wt% sodium hexametaphosphate aqueous solution as a dispersion medium, the particle size is in the range of 1 to 1000 nm and there is one distribution peak. This means that even if the dry powder is present in the state of secondary particles, it is easily dispersed in the primary particles. It means that it is an ultrafine silver oxide powder.
また、本発明に従う超微粒子酸化銀粉末は、Ｘ線回折法による（１１１）面の回折ピークの半値幅が０.２５°以上である。一般に、半値幅をβ、回折角をθとすると、
Ｄ（結晶子サイズ）＝ｋλ／βｃｏｓθ
により、結晶子サイズが求められる。ただし、λはＸ線の波長、ｋは比例定数である。すなわち、半値幅が大きくなると結晶子サイズは小さくなる。後記の実施例に示すように、本発明に従う超微粒子酸化銀粉末の半値幅が０.２５°以上であり、その結果、結晶子サイズはほぼ３０ｎｍ以下である。一次粒子の粒径が５０ｎｍ以下、好ましくは３０ｎｍ以下であることを考えると、その一次粒子はほぼ１個の結晶子からなることを表しており、各一次粒子はほぼ単結晶であることになる。
The ultrafine silver oxide powder according to the present invention has a (111) plane diffraction peak half-value width of 0.25 ° or more as determined by X-ray diffraction. In general, if the half width is β and the diffraction angle is θ,
D (crystallite size) = kλ / βcosθ
Thus, the crystallite size is obtained. Where λ is the wavelength of the X-ray and k is a proportionality constant. That is, as the full width at half maximum increases, the crystallite size decreases. As shown in the examples described later, the full width at half maximum of the ultrafine silver oxide powder according to the present invention is 0.25 ° or more, and as a result, the crystallite size is approximately 30 nm or less. Considering that the primary particles have a particle size of 50 nm or less, preferably 30 nm or less, it indicates that the primary particles are composed of almost one crystallite, and each primary particle is substantially a single crystal. .
このような本発明に従う超微粒子酸化銀粉末は、水酸化ナトリウムまたは水酸化カリウムの１種または２種を合計で０. ５モル／Ｌ以下の量で含む水溶液を中和用液媒体とし、この液媒体に対して、銀塩を６. ０モル／Ｌ以下の量で含む水溶液と、水酸化ナトリウムまたは水酸化カリウムの少なくとも１種の水溶液とを、液のｐＨを１２±１.５の範囲に維持されるように、同時に添加しながら（好ましくはノズルを通じて両液を一定流量で同時に該液媒体中に導入しながら）中和反応を行わせ, 得られた中和殿物をろ過、水洗したあと乾燥することによって得ることができる。場合によっては、該中和殿物をろ別したあと、分散剤または溶媒中に再分散して湿式粉砕し、固液分離したあと乾燥する。 Such an ultrafine silver oxide powder according to the present invention uses an aqueous solution containing one or two kinds of sodium hydroxide or potassium hydroxide in a total amount of 0.5 mol / L or less as a liquid medium for neutralization. An aqueous solution containing a silver salt in an amount of 6.0 mol / L or less with respect to the liquid medium, and at least one aqueous solution of sodium hydroxide or potassium hydroxide, the pH of the liquid is in the range of 12 ± 1.5. The neutralization reaction is carried out while simultaneously adding (preferably introducing both liquids into the liquid medium simultaneously at a constant flow rate through a nozzle) so that the resulting neutralized residue is filtered and washed with water. After that, it can be obtained by drying. In some cases, the neutralized precipitate is filtered off, redispersed in a dispersant or solvent, wet pulverized, solid-liquid separated, and dried.
肝要なことは、アルカリ水溶液と銀塩溶液とを液のｐＨが１２±１.５、好ましくは１２±１.０の範囲内に維持されるように反応させることである。このために、前記の中和用媒体中に、アルカリ水溶液と銀塩溶液とを反応が進行するにつれてもｐＨが変動しないように、両液を中和用液媒体に同時に添加しながら反応を進行させるのがよい。この同時添加によってｐＨの変動を抑えることができ、これによって、酸化銀の核発生を均一に行わせることができ、生成した核を成長させることができる。そのさい、保護コロイドや分散剤を共存させておくと、粒径を制御することができる。 What is important is to react the alkaline aqueous solution and the silver salt solution so that the pH of the solution is maintained within the range of 12 ± 1.5, preferably 12 ± 1.0. For this reason, the reaction proceeds while simultaneously adding both solutions to the neutralization liquid medium so that the pH does not fluctuate as the reaction proceeds between the aqueous alkali solution and the silver salt solution in the neutralization medium. It is good to let them. By this simultaneous addition, fluctuations in pH can be suppressed, whereby nucleation of silver oxide can be performed uniformly, and the generated nuclei can be grown. At that time, the particle size can be controlled by coexisting a protective colloid and a dispersant.
その製造方法の要旨は前述のとおりであるが、これを換言すれば、銀塩とアルカリを水中で反応させて中和殿物を得る工程（中和工程）、得られた中和殿物を固液分離する工程、ろ別した殿物を水洗・乾燥する工程、乾燥物を解砕して粉体を得る工程、その粉体を有機溶媒または分散剤に再分散して湿式粉砕する工程からなるとも言える。これらのうち特に中和工程と湿式粉砕工程の各条件を適正に制御することによって、ＢＥＴ法による比表面積が１.０〜２５ｍ2／g 、一次粒子の平均粒径が１〜５０ｎｍ、二次粒子の平均粒径が１〜１０００ｎｍの酸化銀粉末を得ることができる。以下にその詳細を述べる。 The summary of the production method is as described above. In other words, a step of obtaining a neutralized precipitate by reacting a silver salt and an alkali in water (neutralization step), From the step of solid-liquid separation, the step of washing and drying the filtered product, the step of pulverizing the dried product to obtain a powder, the step of re-dispersing the powder in an organic solvent or dispersant and wet pulverizing It can also be said. Among these, the specific surface area by the BET method is 1.0 to 25 m 2 / g, the average particle size of the primary particles is 1 to 50 nm, and the secondary particles by appropriately controlling the conditions of the neutralization step and the wet pulverization step. A silver oxide powder having an average particle diameter of 1-1000 nm can be obtained. Details are described below.
中和工程において、銀塩としては硝酸銀などを使用することができる。アルカリとしては強アルカリ（例えば水酸化カリウムや水酸化ナトリウムのほか水酸化リチウムなど）を使用する。中和処理はアルカリ水溶液に銀塩の水溶液を添加する方法、アルカリ水溶液と銀塩の水溶液を、中和反応を行わせるために準備した液媒体（実際にはアルカリ水溶液）に同時添加する方法、銀塩の水溶液にアルカリ水溶液を添加するいずれの方法でもよいが、中和反応中の液のｐＨを一定（例えばｐＨ１２程度）にすることにより、溶液中への酸化銀の溶出を低く抑えることができるので、中和反応用に準備した液媒体（アルカリ水溶液）に対して、銀塩の水溶液とアルカリ水溶液を同時に添加する方法が有利である。 In the neutralization step, silver nitrate or the like can be used as the silver salt. As the alkali, a strong alkali (for example, lithium hydroxide as well as potassium hydroxide and sodium hydroxide) is used. Neutralization treatment is a method of adding an aqueous solution of a silver salt to an aqueous alkaline solution, a method of simultaneously adding an aqueous alkaline solution and an aqueous solution of silver salt to a liquid medium (actually an aqueous alkaline solution) prepared for performing a neutralization reaction, Any method of adding an alkaline aqueous solution to an aqueous silver salt solution may be used, but by keeping the pH of the solution during the neutralization reaction constant (for example, about pH 12), elution of silver oxide into the solution can be kept low. Therefore, a method of simultaneously adding an aqueous silver salt solution and an aqueous alkaline solution to the liquid medium (aqueous alkaline solution) prepared for the neutralization reaction is advantageous.
中和反応用の液媒体としてはアルカリ水溶液を用いるのがよく、そのアルカリ水溶液の濃度は０.５モル／Ｌ以下とするのがよい。銀塩溶液の濃度は６.０モル／Ｌ以下、好ましくは３.０モル／Ｌ以下であるのがよい。この銀塩溶液と同時に添加するアルカリ水溶液については、銀塩溶液とアルカリ水溶液とが反応して中和殿物が生成しても、液のｐＨが大きく変動しないような濃度とするのがよい。一般に、銀塩溶液の濃度を低くすると粒径の小さい酸化銀粉末を製造できる。銀塩溶液の濃度範囲（溶質濃度範囲）をこれ以上にすると粒径の大きいものが生成する。二次粒径が１０００ｎｍを超えると、酸化銀を銀に還元する還元温度があまり低下することがなく、酸化銀粉を銀系ペーストとするメリットが小さくなる。また、二次粒径が１０００ｎｍを超えると、これをペーストとした場合、インクジェットからの定量吐出が難しくなったり、配線パターンがにじんだりするという問題が発生する。 As the liquid medium for the neutralization reaction, an alkaline aqueous solution is preferably used, and the concentration of the alkaline aqueous solution is preferably 0.5 mol / L or less. The concentration of the silver salt solution is 6.0 mol / L or less, preferably 3.0 mol / L or less. The alkaline aqueous solution added simultaneously with the silver salt solution should have a concentration such that the pH of the solution does not fluctuate greatly even when the silver salt solution reacts with the alkaline aqueous solution to produce a neutralized precipitate. Generally, when the concentration of the silver salt solution is lowered, a silver oxide powder having a small particle size can be produced. When the concentration range (solute concentration range) of the silver salt solution is higher than this, a product having a large particle size is generated. When the secondary particle size exceeds 1000 nm, the reduction temperature for reducing silver oxide to silver does not decrease so much, and the merit of using silver oxide powder as a silver-based paste is reduced. Further, when the secondary particle diameter exceeds 1000 nm, when this is used as a paste, problems such as difficulty in quantitative discharge from the ink jet and bleeding of the wiring pattern occur.
中和反応中に保護コロイドおよび／または分散剤を共存させることによって、酸化銀の粒成長を抑え、二次粒子径を小さく、比表面積を高くすることができる。保護コロイドとしては、ゼラチン、アラビアゴム、デキストリン、ポリビニルアルコールなどを使用することができる。分散剤としてはヘキサメタリン酸ナトリウム、エチレングリコールなどを使用することができる。保護コロイドは、中和反応用の液媒体や銀塩と同時に添加するアルカリ水溶液中に含有させることもできるが、銀塩の水溶液中に含有させるのが保護コロイドの安定性の点から好ましい。保護コロイドの使用量としては、生成する酸化銀量に対して５重量％以下、好ましくは２重量％以下の量で含有させるのがよい。５重量％より多いと逆に結着材の働きをして凝集粒となることがある。保護コロイドに代えて或いはそれと併用して分散剤を共存させることもできる。分散剤としては、ヘキサメタリン酸ナトリウムまたはエチレングリコールの少なくとも１種であることができ、その使用量は、生成する酸化銀に対して０.１モル／Ｌ以下、好ましくは０.０５モル／Ｌ以下含有させればよい。 By allowing a protective colloid and / or a dispersant to coexist during the neutralization reaction, the growth of silver oxide grains can be suppressed, the secondary particle diameter can be reduced, and the specific surface area can be increased. As the protective colloid, gelatin, gum arabic, dextrin, polyvinyl alcohol and the like can be used. As the dispersant, sodium hexametaphosphate, ethylene glycol, or the like can be used. The protective colloid can be contained in a liquid medium for neutralization reaction or in an alkaline aqueous solution that is added simultaneously with the silver salt. However, the protective colloid is preferably contained in the aqueous silver salt solution from the viewpoint of the stability of the protective colloid. The protective colloid is used in an amount of 5% by weight or less, preferably 2% by weight or less, based on the amount of silver oxide produced. On the other hand, if it exceeds 5% by weight, it may act as a binder and become aggregated particles. A dispersant may be allowed to coexist in place of or in combination with the protective colloid. The dispersant may be at least one of sodium hexametaphosphate or ethylene glycol, and the amount used is 0.1 mol / L or less, preferably 0.05 mol / L or less, based on the silver oxide to be produced. What is necessary is just to contain.
中和反応中のｐＨは１２.０±１.５好ましくは１２±１.０の範囲であるのが良い。銀の溶液中への溶解度がｐＨ１２.０付近で極小となるからである。その範囲外では、溶解・析出による粒成長が起こったり、銀が系外に逃げてしまい収率が悪化するという問題が出てくる。反応温度は１１０℃以下であれば問題ないが、外気温の変化に対しての制御しやすさとコスト面から３０℃以上６０℃以下が好ましい。ただし、保護コロイドおよび／または分散剤の凝固点以上の温度である必要がある。 The pH during the neutralization reaction is in the range of 12.0 ± 1.5, preferably 12 ± 1.0. This is because the solubility of silver in the solution is minimized near pH 12.0. Outside this range, problems such as grain growth due to dissolution / precipitation occur, and silver escapes out of the system and yield deteriorates. There is no problem if the reaction temperature is 110 ° C. or lower, but it is preferably 30 ° C. or higher and 60 ° C. or lower from the viewpoint of ease of control with respect to changes in the outside temperature and cost. However, the temperature needs to be higher than the freezing point of the protective colloid and / or dispersant.
中和反応終了後は、得られた中和澱物を熟成してから固液分離するのが好ましい。中和殿物の熟成は、中和処理後の懸濁液をその温度で１０から１２０分程度保持することによって行う。これにより中和澱物が均一化される。 After completion of the neutralization reaction, the obtained neutralized starch is preferably aged and then solid-liquid separated. The neutralized product is aged by holding the suspension after the neutralization treatment at that temperature for about 10 to 120 minutes. This neutralizes the neutralized starch.
固液分離〜乾燥工程：前記の工程で得られた懸濁液を固液分離し、濾別した澱物を水洗・乾燥して茶色から黒こげ茶色の乾燥物を得る。乾燥は３０℃から２５０℃の温度で行うことができるが、２００℃を超えると酸化銀が分解する恐れがあるので２００℃以下が望ましく、さらに望ましくは１００℃以下がよい。乾燥雰囲気は大気中で行うが、真空雰囲気中でも構わない。 Solid-liquid separation to drying step: The suspension obtained in the above step is subjected to solid-liquid separation, and the filtered starch is washed with water and dried to obtain a brown to dark brown dried product. Drying can be performed at a temperature of 30 ° C. to 250 ° C., but if it exceeds 200 ° C., silver oxide may be decomposed, so that it is preferably 200 ° C. or less, and more preferably 100 ° C. or less. The drying atmosphere is performed in the air, but may be performed in a vacuum atmosphere.
湿式粉砕工程：得られた乾燥物はそのままでも粒径は十分に小さいが、より微粒子化と分散性の向上のためにアルコール、エステル、ケトン、アルデヒドなどの有機溶媒、またはヘキサメタリン酸ナトリウム水溶液中に分散させて湿式粉砕する。湿式粉砕はボールなどのメディアを使用するほうが粉砕効果が高まるので好ましい。粉砕メディアであるボールと粉末と有機溶媒または分散剤を撹拌しながら粉砕する方法によって湿式粉砕処理を行い、メディアを分離した後、固液分離するが、用途に応じて粉末を有機溶媒中または分散剤中に分散させたままの状態としてもよい。 Wet pulverization process: The resulting dried product is still small in particle size, but in an organic solvent such as alcohol, ester, ketone, aldehyde, or aqueous solution of sodium hexametaphosphate in order to make finer particles and improve dispersibility. Disperse and wet pulverize. In wet pulverization, it is preferable to use a medium such as a ball because the pulverization effect is enhanced. Wet grinding is performed by grinding the ball, powder, and organic solvent or dispersant, which is the grinding media, with stirring, and after separating the media, solid-liquid separation is performed, but the powder is dispersed or dispersed in the organic solvent depending on the application. It may be in a state of being dispersed in the agent.
このようにして、本発明によれば、比表面積１.０〜２５.０ｍ2／g 、一次粒子の平均粒径１〜５０ｎｍ、二次粒子の平均粒径１〜１０００ｎｍの超微粒子酸化銀粉末を湿式法で製造することができる。湿式法によれば、例えば特許文献１のような微粒子銀粉末を蒸発法で製造する乾式法よりも製造コストがはるかに低廉となるので、安価な超微粒子酸化銀粉末が得られる。この安価な超微粒子酸化銀粉末を還元剤とともにビヒクルに配合することにより、安価な銀系ペーストが得られる。 Thus, according to the present invention, an ultrafine silver oxide powder having a specific surface area of 1.0 to 25.0 m 2 / g, an average primary particle size of 1 to 50 nm, and an average secondary particle size of 1 to 1000 nm. Can be produced by a wet process. According to the wet method, for example, the production cost is much lower than that of the dry method in which fine particle silver powder as disclosed in Patent Document 1 is produced by the evaporation method, so that an inexpensive ultra fine particle silver oxide powder can be obtained. An inexpensive silver paste can be obtained by blending this inexpensive ultrafine silver oxide powder with a reducing agent in a vehicle.
また、酸化銀粉末を用いた銀系ペーストは高温焼成型の導電ペーストに比較して、低温で融着が起こる点でも有利であるが、とりわけ、本発明に従う超微粒子酸化銀粉末は還元温度が低いので、一層有利となる。従来、高温での取り扱いができなかった基板に対しては樹脂硬化型のペーストが使用されていたが、本発明によれば、これに代わる銀系ペーストを提供でき、導電性に対する信頼性を増すことができる。また、低温で焼成可能であるから基板材質の選択肢が増える点でも有利である。なお、酸化銀の理論密度は７.２ｇ／ｃｃであり、銀の理論密度１０ｇ／ｃｃよりも小さいので、焼成の際の体積収縮が銀よりも一般に大きくなるが、この点は、粒径の異なる酸化銀を混合したり、場合によっては酸化銀粉と銀粉を混合することによって体積収縮を低く抑える方向に改善することが可能である。 Silver-based pastes using silver oxide powder are also advantageous in that fusion occurs at a low temperature compared to high-temperature fired conductive pastes. In particular, the ultrafine silver oxide powder according to the present invention has a reduction temperature. Since it is low, it becomes more advantageous. Conventionally, resin-cured pastes have been used for substrates that could not be handled at high temperatures. However, according to the present invention, an alternative silver-based paste can be provided, which increases the reliability of conductivity. be able to. In addition, since it can be fired at a low temperature, it is advantageous in that the choice of substrate material is increased. The theoretical density of silver oxide is 7.2 g / cc, which is smaller than the theoretical density of silver, 10 g / cc. Therefore, the volume shrinkage during firing is generally larger than that of silver. It is possible to improve the volume shrinkage by mixing different silver oxides or, in some cases, mixing silver oxide powder and silver powder.
〔実施例１〕
液温が５０℃の純水に４８％の水酸化ナトリウム水溶液３.３ｇを添加して４. ６Ｌの中和用の液媒体とした。この液媒体のｐＨは１１.０であった。ゼラチンを酸化銀量に対して０. ５wt％添加した２. ５モル／Ｌの硝酸銀水溶液４００ｍＬと、４８％の水酸化ナトリウム水溶液１８３ｇとを、前記の液媒体に同時に滴下した。 酸に対してのアルカリの量は２当量強である。両液の同時滴下は５分間で全量が添加できるように添加流量を調整した定量ポンプを用いて行った。反応時のｐＨは１１. ５〜１２. ５であった。その後１０分ほど撹拌し、熟成させた。熟成後、中和澱物を固液分離し、十分水洗した後、５０℃での真空乾燥を行って酸化銀粉末を得た。
[Example 1]
To pure water having a liquid temperature of 50 ° C., 3.3 g of a 48% sodium hydroxide aqueous solution was added to obtain a 4.6 L neutralizing liquid medium. The pH of this liquid medium was 11.0. 400 mL of a 2.5 mol / L silver nitrate aqueous solution in which 0.5 wt% of gelatin was added to the amount of silver oxide and 183 g of a 48% sodium hydroxide aqueous solution were simultaneously added dropwise to the liquid medium. The amount of alkali relative to the acid is just over 2 equivalents. The simultaneous addition of both liquids was performed using a metering pump whose addition flow rate was adjusted so that the entire amount could be added in 5 minutes. The pH during the reaction was 11.5 to 12.5. Thereafter, the mixture was stirred for about 10 minutes and aged. After ripening, the neutralized starch was separated into solid and liquid, sufficiently washed with water, and then vacuum dried at 50 ° C. to obtain a silver oxide powder.
得られた酸化銀粉末をイソプロピルアルコールに分散させ、ステンレスボール（１ｍｍφ）を粉砕メディアに使用して、高速撹拌下で湿式粉砕した。 The obtained silver oxide powder was dispersed in isopropyl alcohol, and wet pulverized under high-speed stirring using a stainless ball (1 mmφ) as a pulverizing medium.
得られた分散液を０.２％ヘキサメタリン酸ナトリウム水溶液中に分散させ、レーザー式測定法で粒度分布を測定した。測定装置としては日機装株式会社製マイクロトラックＵＰＡ装置を使用した。そのプロファイルを図１に示した。図１に見られるように、１５ｎｍ付近に鋭角的な１個のピークをもつ分布を示した。また、表１にｄ１０、ｄ５０、ｄ９０（ｎｍ）の値を示した。これらは、累積粒度分布曲線上の１０vol.％、５０vol.％、９０vol.％での粒径（ｎｍ）を示している。 The obtained dispersion was dispersed in a 0.2% sodium hexametaphosphate aqueous solution, and the particle size distribution was measured by a laser measurement method. A Nikkiso Co., Ltd. Microtrac UPA device was used as the measuring device. The profile is shown in FIG. As can be seen in FIG. 1, a distribution having one acute peak near 15 nm was shown. Table 1 shows values of d10, d50, and d90 (nm). These show the particle size (nm) at 10 vol.%, 50 vol.%, And 90 vol.% On the cumulative particle size distribution curve.
さらに、前記の湿式粉砕後の分散液を固液分離し、５０℃での真空乾燥を行って酸化銀粉末を得た。得られた酸化銀粉末をＢＥＴ法による比表面積の測定、粉末Ｘ線回折法の測定、透過電子顕微鏡観察（ＴＥＭ像）、および熱分析に供した。それらの結果を表１に示したが、比表面積は７.６ｍ2／g 、Ｘ線回折の半値幅は０.３７°、結晶子サイズは２１ｎｍであった。Ｘ線回折の半減値および結晶子サイズは、酸化銀（１１１）面からの回折ピークをローレンツ関数を用いて近似したものである。また、ＴＥＭ像を図３に示したが、このＴＥＭ像より求めた１次粒子平均径は３５ｎｍ、２次粒子平均径は１２０ｎｍであった。熱分析では、この酸化銀粉末を大気雰囲気中５℃／分の昇温速度で昇温し、吸熱ピークが現れる温度すなわち非平衡状態での銀への還元温度を測定した。その結果、その還元温度は３６７℃であった。 Furthermore, the dispersion liquid after the wet pulverization was subjected to solid-liquid separation and vacuum drying at 50 ° C. to obtain a silver oxide powder. The obtained silver oxide powder was subjected to measurement of specific surface area by BET method, measurement by powder X-ray diffraction method, observation by transmission electron microscope (TEM image), and thermal analysis. The results are shown in Table 1. The specific surface area was 7.6 m 2 / g, the half width of X-ray diffraction was 0.37 °, and the crystallite size was 21 nm. The X-ray diffraction half-value and crystallite size approximate the diffraction peak from the silver oxide (111) plane using the Lorentz function. Moreover, although the TEM image was shown in FIG. 3, the primary particle average diameter calculated | required from this TEM image was 35 nm, and the secondary particle average diameter was 120 nm. In thermal analysis, this silver oxide powder was heated at a rate of temperature increase of 5 ° C./min in the air atmosphere, and the temperature at which an endothermic peak appeared, that is, the reduction temperature to silver in a non-equilibrium state was measured. As a result, the reduction temperature was 367 ° C.
〔実施例２〕
硝酸銀水溶液として、ゼラチンを酸化銀量に対して０.２５wt％添加した５.０モル／Ｌの硝酸銀水溶液を用いた以外は、実施例１を繰り返した。得られた粉末を実施例１と同様に評価した結果を表１に併記した。
[Example 2]
Example 1 was repeated except that a 5.0 mol / L silver nitrate aqueous solution in which 0.25 wt% of gelatin was added as the silver nitrate aqueous solution was used. The results of evaluating the obtained powder in the same manner as in Example 1 are also shown in Table 1.
〔実施例３〕
硝酸銀水溶液として、ゼラチンを酸化銀量に対して０.２５wt％添加した１.３モル／Ｌの硝酸銀水溶液を用いた以外は、実施例１を繰り返した。得られた粉末を実施例１と同様に評価した結果を表１に併記した。
Example 3
Example 1 was repeated except that a 1.3 mol / L silver nitrate aqueous solution in which 0.25 wt% of gelatin was added as the silver nitrate aqueous solution was used. The results of evaluating the obtained powder in the same manner as in Example 1 are also shown in Table 1.
〔実施例４〕
中和用の液媒体として、液温が３０℃の純水に４８％水酸化ナトリウム水溶液２５ｇを溶解させた液媒体を使用した点、および硝酸銀水溶液として、アラビアゴムを酸化銀量に対して１.０wt％添加した０.６３モル／Ｌの硝酸銀水溶液を使用した点以外は、実施例１を繰り返した。中和反応中のｐＨは１２.８〜１３.２であった。得られた粉末を実施例１と同様に評価した結果を表１に併記した。
Example 4
As a neutralizing liquid medium, a liquid medium in which 25 g of a 48% sodium hydroxide aqueous solution was dissolved in pure water having a liquid temperature of 30 ° C. was used. Example 1 was repeated except that a 0.63 mol / L aqueous silver nitrate solution added with 0.0 wt% was used. The pH during the neutralization reaction was 12.8 to 13.2. The results of evaluating the obtained powder in the same manner as in Example 1 are also shown in Table 1.
〔実施例５〕
ゼラチンを添加しなかった以外は実施例１を繰り返した。得られた粉末を実施例１と同様に評価した結果を表１に併記した。
Example 5
Example 1 was repeated except that no gelatin was added. The results of evaluating the obtained powder in the same manner as in Example 1 are also shown in Table 1.
〔実施例６〕
中和用の液媒体として、純水に４８％水酸化ナトリウム水溶液０.８ｇを添加し且つヘキサメタリン酸ナトリウム３.６ｇを添加した液媒体を使用した点、および硝酸銀水溶液として、ゼラチンを酸化銀量に対して０.５wt％添加した０.６３モル／Ｌの硝酸銀水溶液を使用した点以外は、実施例１を繰り返した。得られた粉末を実施例１と同様に評価した結果を表１に併記した。
Example 6
As a liquid medium for neutralization, a liquid medium in which 0.8 g of 48% sodium hydroxide aqueous solution was added to pure water and 3.6 g of sodium hexametaphosphate was added, and gelatin aqueous solution of silver nitrate as silver nitrate aqueous solution was used. Example 1 was repeated except that a 0.63 mol / L silver nitrate aqueous solution added in an amount of 0.5 wt% was used. The results of evaluating the obtained powder in the same manner as in Example 1 are also shown in Table 1.
〔実施例７〕
硝酸銀水溶液として、ポリビニルアルコールを酸化銀量に対して０.５wt％添加した２.５モル／Ｌの硝酸銀水溶液を用いた以外は、実施例１を繰り返した。得られた粉末を実施例１と同様に評価した結果を表１に併記した。
Example 7
Example 1 was repeated except that as the silver nitrate aqueous solution, a 2.5 mol / L silver nitrate aqueous solution in which 0.5 wt% of polyvinyl alcohol was added to the amount of silver oxide was used. The results of evaluating the obtained powder in the same manner as in Example 1 are also shown in Table 1.
〔実施例８〕
湿式粉砕を行わなかった以外は、実施例７を繰り返した。反応後の中和澱物を固液分離したあと５０℃で真空乾燥を行った酸化銀粉末についての評価した結果を表１に示した。
Example 8
Example 7 was repeated except that wet grinding was not performed. Table 1 shows the evaluation results of the silver oxide powder that was subjected to solid-liquid separation of the neutralized starch after the reaction and vacuum-dried at 50 ° C.
〔比較例１〕
４８重量％の水酸化ナトリウム１８３ｇを溶解して４.６Ｌとした水酸化ナトリウム水溶液を５０℃に調温し、この水酸化ナトリウム水溶液に対して、ポリビニルアルコールを酸化銀量に対して０.５wt％添加した２.５モル／Ｌの硝酸銀水溶液４００ｍｌを添加した。すなわち、水酸化ナトリウム水溶液に硝酸銀水溶液を添加するいわゆる逆中和方式で反応させた。得られた中和澱物を固液分離し、十分に水洗したのち，５０℃での真空乾燥を行った酸化銀粉末について評価した結果を表１に示す。
[Comparative Example 1]
A sodium hydroxide aqueous solution prepared by dissolving 183 g of 48% by weight sodium hydroxide to 4.6 L was adjusted to 50 ° C., and polyvinyl alcohol was added to 0.5 wt. 400 ml of a 2.5 mol / L aqueous silver nitrate solution with a% addition was added. That is, the reaction was performed by a so-called reverse neutralization method in which an aqueous silver nitrate solution was added to an aqueous sodium hydroxide solution. Table 1 shows the results of evaluating the silver oxide powder obtained by solid-liquid separation of the obtained neutralized starch, washing thoroughly with water, and then vacuum drying at 50 ° C.
この粉末の粒度分布を実施例１と同様に測定したさいのプロファイルを図２に示した。また、この粉末のＴＥＭ像を図４に示した。 FIG. 2 shows a profile when the particle size distribution of the powder was measured in the same manner as in Example 1. Moreover, the TEM image of this powder was shown in FIG.
〔比較例２〕
液温が５０℃で０.０１モル／Ｌの水酸化ナトリウムを水に溶解した４.６Ｌの液媒体中に、６.５ｍｏｌ／Ｌの硝酸銀水溶液４００ｍｌと、４８％の水酸化ナトリウム水溶液４７６ｇとを同時滴下して反応させた。反応後、中和澱物を固液分離して５０℃での真空乾燥を行った酸化粉末について評価した結果を表１に示した。
[Comparative Example 2]
In a 4.6 L liquid medium in which 0.01 mol / L sodium hydroxide was dissolved in water at a liquid temperature of 50 ° C., 400 ml of a 6.5 mol / L silver nitrate aqueous solution, 476 g of a 48% sodium hydroxide aqueous solution, Were reacted dropwise at the same time. Table 1 shows the results of evaluating the oxidized powder obtained by subjecting the neutralized starch to solid-liquid separation after the reaction and vacuum drying at 50 ° C.
表１（さらには図１〜４）に見られるように、実施例１〜８の酸化銀粉末は、比表面積が１ｍ2／g 以上実際には２〜２０ｍ2／g で、１次粒径が１〜５０ｎｍ実際には１〜３０ｎｍ、２次粒径が１μｍ以下実際には２００ｎｍ以下、Ｘ線回折法による（１１１）面の回折ピークの半値幅が０.２５°以上であり、粒度分布においてピークが１個（図１）である。その結果、還元温度が４００℃以下である。これに対して、比較例１〜２のものは、粒度分布が生じて２次粒径も大きくなっており、比表面積と粒度とのバランスが良くない。その結果、還元温度は４００℃よりも高くなっている。 As can be seen in Table 1 (and also FIGS. 1 to 4), the silver oxide powders of Examples 1 to 8 have a specific surface area of 1 m 2 / g or more and actually 2 to 20 m 2 / g and a primary particle size. Is actually 1-30 nm, the secondary particle size is 1 μm or less, actually 200 nm or less, the half-value width of the diffraction peak of the (111) plane by the X-ray diffraction method is 0.25 ° or more, and the particle size distribution 1 has one peak (FIG. 1). As a result, the reduction temperature is 400 ° C. or lower. On the other hand, in Comparative Examples 1 and 2, the particle size distribution is generated and the secondary particle size is large, and the balance between the specific surface area and the particle size is not good. As a result, the reduction temperature is higher than 400 ° C.
またこれらの実施例および比較例の結果から、本発明に従う超微粒子の酸化銀粉末を得るには、保護コロイドを使用すること、湿式粉砕を行うこと、硝酸銀と水酸化ナトリウムとを液媒体に対して両者を同時投入する、いわゆる同時中和方式を採用すること、反応時のｐＨを１２.０±１.５の範囲に管理することが、それぞれ有益に作用することがわかる。より具体的には、比較例１および２と実施例１との対比から本発明に従う超微粒子を得るには保護コロイドの使用と湿式粉砕が有益であることがわかる。実施例１と５の比較から、保護コロイドの存在下で反応させることにより、１次粒径および２次粒径が小さく、比表面積の大きな超微粒子が得られることがわかる。さらに、実施例８と比較例１との比較から、本発明に従う超微粒子を得るには硝酸銀と水酸化ナトリウムの同時投入による中和方式によるのがよいことがわかる。実施例６からは液媒体に分散剤を添加しておくと１次粒子が分散して比表面積が大きな粉体が得られることがわかる。 Also, from the results of these Examples and Comparative Examples, in order to obtain ultrafine silver oxide powder according to the present invention, the use of protective colloid, wet grinding, silver nitrate and sodium hydroxide with respect to the liquid medium It can be seen that adopting a so-called simultaneous neutralization method in which both are added simultaneously, and controlling the pH during the reaction in the range of 12.0 ± 1.5, respectively, have beneficial effects. More specifically, it can be seen from the comparison between Comparative Examples 1 and 2 and Example 1 that the use of protective colloid and wet grinding are beneficial to obtain ultrafine particles according to the present invention. From a comparison between Examples 1 and 5, it can be seen that ultrafine particles having a small primary particle size and a secondary particle size and a large specific surface area can be obtained by the reaction in the presence of the protective colloid. Furthermore, from comparison between Example 8 and Comparative Example 1, it is understood that the neutralization method by simultaneous addition of silver nitrate and sodium hydroxide is good for obtaining ultrafine particles according to the present invention. Example 6 shows that when a dispersant is added to the liquid medium, the primary particles are dispersed to obtain a powder having a large specific surface area.
Claims (12)
ｎｍ、二次粒子の平均粒径が１〜１０００ｎｍである微粒子酸化銀粉末。 The specific surface area by BET method is 1.0-25.0 m 2 / g, and the average particle size of primary particles is 1-50.
Fine particle silver oxide powder having an average particle size of 1 nm to 1000 nm, and secondary particles.
ークが１つである請求項１に記載の微粒子酸化銀粉末。 2. The particle size distribution measurement by a laser method using a 0.2 wt% sodium hexametaphosphate aqueous solution as a dispersion medium has a particle size in the range of 1 to 1000 nm and has one particle size distribution peak. Fine particle silver oxide powder.
または２に記載の微粒子酸化銀粉末。 2. The half width of a diffraction peak of (111) plane by X-ray diffraction method is 0.25 ° or more.
Or 2. Fine grained silver oxide powder according to 2.
からなる請求項１に記載の微粒子酸化銀粉末の製造方法。 An aqueous solution containing one or two kinds of sodium hydroxide or potassium hydroxide in a total amount of 0.5 mol / L or less is used as a neutralizing liquid medium, and 6.0 mol of silver salt is added to this liquid medium. / L or less and an aqueous solution containing at least one kind of sodium hydroxide or potassium hydroxide are simultaneously added to cause a neutralization reaction, and the pH of the liquid during the neutralization reaction is 12 ±. Maintaining in the range of 1.5, and filtering, washing and drying the resulting neutralized residue,
The method for producing fine-grained silver oxide powder according to claim 1, comprising:
の製造方法。 An aqueous solution containing one or two kinds of sodium hydroxide or potassium hydroxide in a total amount of 0.5 mol / L or less is used as a neutralizing liquid medium, and 6.0 mol of silver salt is added to this liquid medium. / L or less and an aqueous solution containing at least one kind of sodium hydroxide or potassium hydroxide are simultaneously added to cause a neutralization reaction, and the pH of the liquid during the neutralization reaction is 12 ±. 2. Maintaining a range of 1.5, and filtering the obtained neutralized residue from the liquid, then redispersing in a dispersant or an organic solvent and wet-grinding. Of producing fine grain silver oxide powder.
からなる請求項１に記載の微粒子酸化銀粉末の製造方法。 An aqueous solution containing one or two kinds of sodium hydroxide or potassium hydroxide in a total amount of 0.5 mol / L or less is used as a neutralizing liquid medium, and 6.0 mol of silver salt is added to this liquid medium. / L or less and an aqueous solution containing at least one kind of sodium hydroxide or potassium hydroxide are simultaneously added to cause a neutralization reaction, and the pH of the liquid during the neutralization reaction is 12 ±. Maintaining in the range of 1.5, causing the neutralization reaction to be performed in the presence of a protective colloid and / or a dispersant, and performing the neutralization reaction at a temperature not lower than the freezing point of the protective colloid and / or the dispersant and not higher than 110 ° C. Letting the temperature neutralize, and filtering, washing and drying the resulting neutralized residue,
The method for producing fine-grained silver oxide powder according to claim 1, comprising:
の製造方法。 An aqueous solution containing one or two kinds of sodium hydroxide or potassium hydroxide in a total amount of 0.5 mol / L or less is used as a neutralizing liquid medium, and 6.0 mol of silver salt is added to this liquid medium. / L or less and an aqueous solution containing at least one kind of sodium hydroxide or potassium hydroxide are simultaneously added to cause a neutralization reaction, and the pH of the liquid during the neutralization reaction is 12 ±. Maintaining in the range of 1.5, causing the neutralization reaction to be performed in the presence of a protective colloid and / or a dispersant, and performing the neutralization reaction at a temperature not lower than the freezing point of the protective colloid and / or the dispersant and not higher than 110 ° C. The fine-grain silver oxide according to claim 1, which comprises: carrying out at a temperature; and filtering the obtained neutralized precipitate from the liquid, redispersing in a dispersant or an organic solvent, and wet-grinding. Powder manufacturing method.
の少なくとも１種である請求項６または７に記載の製造方法。 The production method according to claim 6 or 7, wherein the protective colloid is at least one of gelatin, gum arabic, dextrin, or polyvinyl alcohol.
る請求項６または７に記載の製造方法。 The manufacturing method according to claim 6 or 7, wherein the dispersant is at least one of sodium hexametaphosphate and ethylene glycol.
ある請求項５または７に記載の製造方法。 The method according to claim 5 or 7, wherein the organic solvent is at least one of alcohols, esters, ketones, and aldehydes.
ムに分散させてなる微粒子酸化銀粉分散液。 A fine silver oxide powder dispersion obtained by dispersing the silver oxide powder according to claim 1, 2 or 3 in an organic solvent or sodium hexametaphosphate.
る請求項１１に記載の分散液。 The dispersion according to claim 11, wherein the organic solvent is at least one of alcohols, esters, ketones, and aldehydes.
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| US20120189534A1 (en) * | 2011-01-25 | 2012-07-26 | Syed Tajammul Hussain | Method of manufacture of silver oxide nano particles |
| JP2012176892A (en) * | 2012-06-08 | 2012-09-13 | Dowa Hightech Co Ltd | Method for producing silver oxide powder |
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