TW201728760A - Conductive paste for printing and method of manufacturing same, and method of preparing dispersion of silver nanoparticles - Google Patents

Abstract

The invention enables the production of low-temperature-sinterable conductive pastes at various viscosities that are suitable for the creation of conductive bodies with favorable conductive performance. A method of preparing a dispersion of silver nanoparticles having a surface coating layer formed from coating agent molecules and having an average particle diameter of 5 to 20 nm includes a step (a) of treating silver (I) oxide powder with formic acid in a hydrocarbon solvent, thereby converting the silver (I) oxide powder to silver (I) formate, and a step (b) of reducing the silver cations in the silver (I) formate to silver atoms by a reduction with an amine compound, within the hydrocarbon solvent and in the presence of a monocarboxylic acid having a carbon number of 8 to 11, thereby forming silver nanoparticles with an average particle diameter of 5 to 20 nm, the surfaces of which have been coated with the amine compound and the monocarboxylic acid, wherein a primary amine with a carbon number of 9 to 11 and a secondary amine are used as the amine compound. The invention also provides a conductive past for printing that uses this dispersion.

Description

印刷用導電性糊劑及其調製方法與銀奈米粒子分散液之調製方法Conductive paste for printing, preparation method thereof and method for preparing silver nanoparticle dispersion

本發明關於以氧化銀作為初始原料來調製銀奈米粒子分散液之方法。又，本發明關於含有銀奈米粒子之印刷用導電性糊劑及其調製方法。The present invention relates to a method for preparing a silver nanoparticle dispersion using silver oxide as a starting material. Further, the present invention relates to a conductive paste for printing containing silver nanoparticles and a method for preparing the same.

利用銀奈米粒子之導電性糊劑係例如被使用於微細的電路層之形成。The conductive paste using silver nanoparticles is used, for example, in the formation of a fine circuit layer.

銀奈米粒子表面之銀原子在表面上的移動能特別大，故銀奈米粒子相互接觸的話，因表面之銀原子相互地移動而會有強烈引發融合的傾向。此融合在室溫附近仍會進行。因此，為了防止導電性糊劑中所含的銀奈米粒子相互地融合並形成凝聚粒子，通常會利用被覆劑分子被覆銀奈米粒子的表面，並防止銀奈米粒子相互直接接觸其金屬表面。The silver atoms on the surface of the silver nanoparticles have a particularly large movement on the surface. Therefore, when the silver nanoparticles are in contact with each other, the silver atoms on the surface move toward each other, and the fusion tends to be strongly induced. This fusion will still occur near room temperature. Therefore, in order to prevent the silver nanoparticles contained in the conductive paste from merging with each other and forming agglomerated particles, the surface of the silver nanoparticles is usually coated with the coating molecules, and the silver nanoparticles are prevented from directly contacting each other with the metal surface. .

專利文獻1記載：使粉末狀氧化銀分散於非極性溶劑中，添加過量的甲酸使甲酸作用於該粉末狀氧化銀而轉化為粉末狀甲酸銀(HCOOAg)，再使1級胺作用於該粉末狀甲酸銀而製成甲酸銀之1級胺加成鹽之後，在液溫約70℃實施該甲酸銀之1級胺加成鹽的分解性還原反應，調製具有由1級胺構成的表面被覆層之銀奈米粒子的方法。使用碳數7~12之烷基胺等作為1級胺。Patent Document 1 discloses that powdered silver oxide is dispersed in a non-polar solvent, and excess formic acid is added to cause formic acid to act on the powdery silver oxide to be converted into powdered silver formate (HCOOAg), and then a primary amine is allowed to act on the powder. After the silver formate is used to prepare a silver-based first-grade amine addition salt, the decomposable reduction reaction of the silver formate first-grade amine addition salt is carried out at a liquid temperature of about 70 ° C to prepare a surface coating composed of a primary amine. A method of layering silver nanoparticles. As the primary amine, an alkylamine having 7 to 12 carbon atoms is used.

專利文獻2記載：含有桿狀奈米粒子之金屬奈米粒子的製造方法，其包含以下階段：將含有包含2級胺之胺化合物、金屬前驅物及非極性溶劑之混合物於60乃至300℃加熱形成至少具有桿狀金屬氧化物奈米粒子之金屬氧化物奈米粒子中間體；將封蓋分子(capping molecule)及還原劑添加於前述混合物中，並於90乃至150℃加熱形成金屬奈米粒子；及，回收前述金屬奈米粒子。Patent Document 2 describes a method for producing metal nanoparticles containing rod-shaped nanoparticles, which comprises heating a mixture containing an amine compound containing a secondary amine, a metal precursor, and a nonpolar solvent at 60 to 300 ° C. Forming a metal oxide nanoparticle intermediate having at least rod-shaped metal oxide nanoparticles; adding a capping molecule and a reducing agent to the mixture, and heating at 90 to 150 ° C to form metal nanoparticles And recovering the aforementioned metal nanoparticles.

專利文獻3記載：將金屬化合物於含有1級胺及3級胺的溶液中加熱、還原，藉此獲得奈米級之金屬微粒分散於溶液中而得的金屬微粒分散液之金屬微粒分散液的製造方法，其特徵為：前述3級胺含有碳數為2以上之烷基。Patent Document 3 discloses that a metal compound is obtained by heating and reducing a metal compound in a solution containing a primary amine and a tertiary amine, thereby obtaining a metal fine particle dispersion of a metal fine particle dispersion obtained by dispersing nanometer-sized metal fine particles in a solution. The production method is characterized in that the tertiary amine contains an alkyl group having 2 or more carbon atoms.

專利文獻4記載：將由具有羧基之有機化合物構成的保護劑被覆於金屬奈米粒子表面而成的被覆金屬奈米粒子分散至含有多元醇醚之極性分散溶劑中而構成的金屬奈米粒子分散液。Patent Document 4 discloses a metal nanoparticle dispersion in which a coated metal nanoparticle obtained by coating a surface of a metal nanoparticle with a protective agent composed of an organic compound having a carboxyl group is dispersed in a polar dispersion solvent containing a polyol ether. .

專利文獻5記載：利用胺化合物所為之還原反應將甲酸銀(I)中所含的銀陽離子還原為銀原子，形成在表面被胺化合物被覆而成的銀奈米粒子時，使用1級胺與2級胺兩者作為胺化合物之銀奈米粒子之調製方法。Patent Document 5 discloses that a silver cation contained in silver formate (I) is reduced to a silver atom by a reduction reaction by an amine compound, and when a silver nanoparticle having a surface coated with an amine compound is formed, a primary amine is used. Both of the secondary amines are used as a method of preparing silver nanoparticles of an amine compound.

專利文獻6記載：利用凸版反轉印刷法形成導電性圖案用之實質上不含黏結劑成分之導電性印墨，其特徵為：以體積平均粒徑(Mv)為10~700nm之導電性粒子、脫模劑、表面能量調整劑、溶劑成分作為必要成分，前述溶劑成分為在25℃之表面能量為27mN/m以上之溶劑與在大氣壓下之沸點為120℃以下之揮發性溶劑的混合物，在25℃的印墨之表面能量為10~21mN/m。 [先前技術文獻] [專利文獻]Patent Document 6 describes a conductive ink for forming a conductive pattern substantially free of a binder component by a letterpress reverse printing method, and is characterized in that conductive particles having a volume average particle diameter (Mv) of 10 to 700 nm are used. The mold release agent, the surface energy adjuster, and the solvent component are essential components, and the solvent component is a mixture of a solvent having a surface energy of 27 mN/m or more at 25 ° C and a volatile solvent having a boiling point of 120 ° C or less at atmospheric pressure. The surface energy of the ink at 25 ° C is 10 to 21 mN/m. [Prior Technical Literature] [Patent Literature]

[專利文獻1]日本特開2011-153362號公報 [專利文獻2]日本特開2009-084677號公報 [專利文獻3]日本特開2008-081828號公報 [專利文獻4]日本特開2011-038128號公報 [專利文獻5]日本特開2015-161008號公報 [專利文獻6]WO2008/111484A1[Patent Document 1] Japanese Laid-Open Patent Publication No. JP-A-2009-084677 (Patent Document 3) JP-A-2008-081828 (Patent Document 4) JP-A-2011-038128 [Patent Document 5] Japanese Laid-Open Patent Publication No. 2015-161008 [Patent Document 6] WO2008/111484A1

[發明所欲解決之課題] 使用以專利文獻1的方法調製而成的銀奈米粒子的話，可獲得如在約120℃之低溫燒結而得到導電體之所謂低溫燒結型的導電性糊劑。但是，在如此的銀奈米粒子中，被覆於銀的被覆劑量較多。亦即，被覆劑相對於銀之比例較大。[Problems to be Solved by the Invention] When the silver nanoparticles prepared by the method of Patent Document 1 are used, a so-called low-temperature sintering type conductive paste obtained by sintering at a low temperature of about 120 ° C to obtain a conductor can be obtained. However, in such silver nanoparticles, the amount of coating coated with silver is large. That is, the ratio of the coating agent to silver is large.

因此，欲使用含有如此的銀奈米粒子之導電性糊劑來形成厚的導體膜的話，有時會有在煅燒時被覆劑因不易從導電性糊劑膜去除而導致導體膜之導電性能降低的情況，或因在煅燒時的體積收縮所導致導體膜產生裂紋的情況。因此，使用如此的導電性糊劑時，能形成的膜厚有所限制。Therefore, when a conductive paste containing such silver nanoparticles is used to form a thick conductor film, there is a case where the coating agent is less likely to be removed from the conductive paste film during firing, and the conductive property of the conductor film is lowered. The case, or the case where the conductor film is cracked due to volume shrinkage at the time of calcination. Therefore, when such a conductive paste is used, the film thickness which can be formed is limited.

又，因前述理由(被覆劑量多)，使用以專利文獻1的方法調製而成的銀奈米粒子來製造導電性印墨時，僅能提供較低黏度之印墨。因此，適於如此的印墨之印刷或塗佈方法限於噴墨等之印刷方式、或旋塗、浸漬等之塗佈方法。Moreover, for the reason described above (the amount of coating is large), when the conductive ink is produced using the silver nanoparticles prepared by the method of Patent Document 1, only the ink having a lower viscosity can be provided. Therefore, the printing or coating method suitable for such an ink is limited to a printing method such as inkjet or a coating method such as spin coating or dipping.

亦即，就低溫燒結型之導電性糊劑而言，尋求可獲得燒結後無裂紋且導電性能良好的導電體，同時能調整為各種黏度者。因此，對適於製造如此的導電性糊劑之銀奈米粒子分散液會有需求。In other words, in the case of the low-temperature sintering type conductive paste, it is desired to obtain a conductor having no crack after sintering and having good electrical conductivity, and can be adjusted to various viscosities. Therefore, there is a need for a silver nanoparticle dispersion suitable for producing such a conductive paste.

專利文獻2~6亦未教示在此點優良的銀奈米粒子分散液。Patent Documents 2 to 6 also do not teach a silver nanoparticle dispersion liquid which is excellent at this point.

本發明之目的係提供：能以各種黏度調製適於製成無裂紋且導電性能良好的導電體之可低溫煅燒的導電性糊劑之導電性糊劑之調製方法，尤其是提供：印刷用導電性糊劑之調製方法。SUMMARY OF THE INVENTION The object of the present invention is to provide a method for preparing a conductive paste of a low-temperature calcinable conductive paste suitable for forming a conductor having no crack and good electrical conductivity with various viscosities, in particular, providing conductive for printing Modulation method of sexual paste.

本發明另一目的係提供：調製可適用於製造如上述的導電性糊劑之銀奈米粒子分散液的方法。Another object of the present invention is to provide a method of preparing a silver nanoparticle dispersion liquid which is applicable to the production of the conductive paste as described above.

本發明再一目的係提供：適於製成無裂紋且導電性能良好的導電體之可低溫煅燒的印刷用導電性糊劑，其能擁有各種黏度。 [解決課題之手段]Still another object of the present invention is to provide a low-temperature calcinable conductive paste for printing which is suitable for producing a crack-free and electrically conductive conductor, which can have various viscosities. [Means for solving the problem]

根據本發明之一種態樣，係提供： 一種銀奈米粒子分散液之調製方法，係調製在表面具有由被覆劑分子構成的被覆層之平均粒徑5~20nm的銀奈米粒子之分散液的方法，其特徵為： 包含以下步驟： a) 在烴溶劑中，使甲酸作用於粉末狀氧化銀(I)，使粉末狀氧化銀(I)轉化為甲酸銀(I)；及 b) 在前述烴溶劑中，於碳數8~11之單元羧酸的存在下，利用胺化合物所為之還原反應將甲酸銀(I)中所含的銀陽離子還原為銀原子，藉此形成表面被胺化合物及單元羧酸被覆而成之平均粒徑5~20nm之銀奈米粒子； 使用碳數9~11之1級胺與2級胺兩者作為前述胺化合物。According to an aspect of the present invention, there is provided a method for preparing a silver nanoparticle dispersion, which comprises dispersing a silver nanoparticle having an average particle diameter of 5 to 20 nm of a coating layer composed of a coating agent molecule on a surface thereof. The method comprising the steps of: a) reacting formic acid in powdered silver oxide (I) in a hydrocarbon solvent to convert powdered silver (I) oxide to silver formate (I); and b) In the above hydrocarbon solvent, the silver cation contained in the silver formate (I) is reduced to a silver atom by a reduction reaction in the presence of a carboxylic acid having 8 to 11 carbon atoms, thereby forming a surface-imparted amine compound. And a silver nanoparticle having an average particle diameter of 5 to 20 nm which is coated with a unit carboxylic acid; and both of the amine having a carbon number of 9 to 11 and a second amine are used as the amine compound.

前述烴溶劑係具有65℃~155℃的沸點之碳數6~9的直鏈或環狀烷， 在步驟a中，就前述粉末狀氧化銀(I)每100質量份使用前述烴溶劑400質量份~700質量份較理想。The hydrocarbon solvent is a linear or cyclic alkane having a carbon number of 6 to 9 having a boiling point of 65 ° C to 155 ° C, and in the step a, the mass of the hydrocarbon solvent 400 is used per 100 parts by mass of the powdery silver oxide (I). ~700 parts by mass is ideal.

前述1級胺之分子量為120~200； 前述1級胺具有對前述烴溶劑有親和性之脂肪族烴鏈較理想。The molecular weight of the first-stage amine is from 120 to 200; and the above-mentioned first-grade amine preferably has an aliphatic hydrocarbon chain having affinity for the hydrocarbon solvent.

前述2級胺之分子量為100~150； 前述2級胺具有對前述烴溶劑有親和性之脂肪族烴鏈較理想。The molecular weight of the above-mentioned secondary amine is from 100 to 150; and the above-mentioned secondary amine has an aliphatic hydrocarbon chain having an affinity for the hydrocarbon solvent.

在步驟b中，就甲酸銀(I)所含的銀陽離子每1莫耳量， 使用前述單元羧酸0.05莫耳量~0.3莫耳量； 使用前述1級胺0.05莫耳量~0.3莫耳量； 及使用前述2級胺，以使1級胺與2級胺之總莫耳量為1.1莫耳量~1.5莫耳量之範圍較理想。In the step b, the silver cation contained in the silver (I) formic acid is used in an amount of 0.05 moles to 0.3 moles per unit of the carboxylic acid; and the above-mentioned first amine is 0.05 moles to 0.3 moles. The amount of the above-mentioned second-grade amine is preferably such that the total molar amount of the primary amine and the secondary amine is from 1.1 moles to 1.5 moles.

前述銀奈米粒子分散液之調製方法更包含下述步驟c~e較理想： c) 在減壓下使前述烴溶劑氣化而從得自於步驟b之反應液去除，藉此回收含有前述銀奈米粒子之殘渣； d) 以醇清洗該殘渣；及 e) 使在步驟d清洗後的殘渣分散於和前述烴溶劑相同或不同的烴溶劑中而獲得銀奈米粒子分散液。The method for preparing the silver nanoparticle dispersion further includes the following steps c to e: c) the hydrocarbon solvent is vaporized under reduced pressure and removed from the reaction liquid obtained in the step b, whereby the recovery includes the foregoing The residue of the silver nanoparticles; d) washing the residue with alcohol; and e) dispersing the residue after the step d washing in a hydrocarbon solvent which is the same as or different from the hydrocarbon solvent to obtain a silver nanoparticle dispersion.

根據本發明之另一態樣，係提供： 一種印刷用導電性糊劑之調製方法，係使用利用前述方法調製而成的銀奈米粒子分散液來調製印刷用導電性糊劑。According to another aspect of the present invention, there is provided a method for preparing a conductive paste for printing, which comprises preparing a conductive paste for printing using a silver nanoparticle dispersion prepared by the above method.

根據本發明之又一態樣，係提供： 一種印刷用導電性糊劑， 含有在表面具有由被覆劑分子構成的被覆層之平均粒徑5~20nm的銀奈米粒子； 前述被覆層含有碳數8~11之單元羧酸及碳數9~11之1級胺。 [發明之效果]According to still another aspect of the present invention, there is provided a conductive paste for printing comprising silver nanoparticles having an average particle diameter of 5 to 20 nm of a coating layer composed of a coating agent molecule on a surface thereof; The number of carboxylic acids of 8 to 11 and the amine of 9 to 11 carbon atoms. [Effects of the Invention]

根據本發明係提供：能以各種黏度調製適於製成無裂紋且導電性能良好的導電體之可低溫煅燒的導電性糊劑之導電性糊劑之調製方法，尤其是提供：印刷用導電性糊劑之調製方法。According to the present invention, there is provided a method for preparing a conductive paste capable of preparing a low-temperature calcined conductive paste which is suitable for forming a conductor having no crack and having good electrical conductivity with various viscosities, and more particularly, provides conductivity for printing. Modulation method of paste.

又根據本發明係提供：調製可適用於製造如上述的導電性糊劑之銀奈米粒子分散液的方法。Further, according to the present invention, there is provided a method of preparing a silver nanoparticle dispersion liquid which can be suitably used for producing the conductive paste as described above.

再根據本發明係提供：適於製成無裂紋且導電性能良好的導電體之可低溫煅燒的印刷用導電性糊劑，其能擁有各種黏度。Further, according to the present invention, there is provided a low-temperature calcinable conductive paste for printing which is suitable for producing a crack-free and electrically conductive conductor, which can have various viscosities.

本發明人們發現：在烴溶劑中，使粉末狀氧化銀(I)與甲酸作用獲得甲酸銀(I)，然後，以胺化合物將甲酸銀(I)所含的銀陽離子還原為銀原子，在製造表面被胺化合物被覆而成的銀奈米粒子時，藉由併用1級胺(碳數9~11)與2級胺作為胺化合物，然後，在碳數8~11之單元羧酸的存在下實施胺化合物所為之還原，藉此可調製被覆於銀之被覆劑的量少之銀奈米粒子。本發明係基於如此發現而成。The present inventors have found that in a hydrocarbon solvent, powdery silver (I) is reacted with formic acid to obtain silver formate (I), and then the silver cation contained in the silver (I) formic acid is reduced to a silver atom by an amine compound. When a silver nanoparticle having a surface coated with an amine compound is produced, a first-order amine (carbon number 9 to 11) and a second-order amine are used as an amine compound, and then, in the presence of a carboxylic acid having a carbon number of 8 to 11. The reduction of the amine compound is carried out, whereby silver nanoparticle having a small amount of the coating agent coated with silver can be prepared. The present invention has been discovered based on this.

本發明關於調製在表面具有由被覆劑分子構成的被覆層之銀奈米粒子的方法，尤其是關於調製銀奈米粒子分散於液體中而成的銀奈米粒子分散液之方法。The present invention relates to a method of preparing silver nanoparticles having a coating layer composed of a coating agent molecule on a surface thereof, and more particularly to a method for preparing a silver nanoparticle dispersion in which silver nanoparticles are dispersed in a liquid.

根據本發明可製造平均粒徑為奈米級，尤其是平均粒徑為5nm以上20nm以下之銀奈米粒子。考量銀奈米粒子分散液之良好的分散安定性、與使用銀奈米粒子分散液製得的導電性糊劑能在低溫煅燒兩者，而選出上述平均粒徑之範圍(5~20nm)。According to the present invention, it is possible to produce silver nanoparticles having an average particle diameter of nanometers, particularly an average particle diameter of 5 nm or more and 20 nm or less. Considering the good dispersion stability of the silver nanoparticle dispersion and the conductive paste prepared by using the silver nanoparticle dispersion, both of them can be calcined at a low temperature, and the above average particle diameter range (5 to 20 nm) is selected.

就達成平均粒徑5~20nm而言，在還原甲酸銀時，1級胺的存在係為必要。藉由在還原甲酸銀時存在1級胺，其會配位於生成的奈米粒子並抑制粒子之肥大化。未添加1級胺而實施甲酸銀之還原的話，在經過奈米粒子後，肥大化會進行並沉降。1級胺的量多者粒徑會變小。可藉由增減1級胺的使用量來調整平均粒徑。此外，藉由單元羧酸配位於生成的奈米粒子，可使分散性安定性提昇。In order to achieve an average particle diameter of 5 to 20 nm, the presence of a primary amine is necessary in the case of reducing silver formate. By the presence of a primary amine in the reduction of silver formate, it will coordinate with the resulting nanoparticles and inhibit the enlargement of the particles. When the reduction of silver formate is carried out without adding a first-order amine, after the nanoparticle is passed, the enlargement proceeds and sedimentation occurs. When the amount of the first-grade amine is large, the particle diameter becomes small. The average particle diameter can be adjusted by increasing or decreasing the amount of the amine used in the first stage. Further, by disposing the unit carboxylic acid in the produced nanoparticle, the dispersibility stability can be improved.

[用語] 本說明書中，平均粒徑係指在利用雷射繞射法測量而得的粒度分佈(體積基準)中，累計值50%之粒徑。 用語「沸點」意指在1大氣壓的沸點。 用語「印墨」意指糊劑之中特別適於印刷者。 又，提及銀奈米粒子的量(質量、含量)時，除非另有說明，否則意指僅銀奈米粒子(因此不含被覆劑)的量。另一方面，提及銀奈米粒子的粒徑時，除非另有說明，否則意指包含附著於銀奈米粒子的表面之被覆劑的粒徑。 用語「1級胺」意指分子中僅具有1個1級胺基之化合物。即使具有2級胺基及/或3級胺基，若為具有1個1級胺基之化合物，仍歸屬於1級胺。 用語「2級胺」意指分子中僅具有1個胺基且該胺基為2級胺基之化合物。[Glossary] In the present specification, the average particle diameter refers to a particle diameter of 50% of the cumulative value in the particle size distribution (volume basis) measured by the laser diffraction method. The term "boiling point" means the boiling point at 1 atmosphere. The term "printed ink" means that the paste is particularly suitable for the printer. Further, when referring to the amount (mass, content) of the silver nanoparticle, unless otherwise stated, it means the amount of only silver nanoparticle (and thus no coating agent). On the other hand, when referring to the particle diameter of the silver nanoparticle, unless otherwise stated, it means the particle diameter of the coating material which adheres to the surface of a silver nanoparticle. The term "grade 1 amine" means a compound having only one primary amino group in the molecule. Even if it has a 2-stage amine group and/or a 3-stage amine group, if it is a compound which has one 1-stage amine group, it belongs to a 1st grade amine. The term "secondary amine" means a compound having only one amine group in the molecule and the amine group being a grade 2 amine group.

[步驟a及b] 本發明中實施步驟a及b。 a) 在烴溶劑中，使甲酸作用於粉末狀氧化銀(I)，使粉末狀氧化銀(I)轉化為甲酸銀(I)。 b) 在前述烴溶劑中，於碳數8~11之單元羧酸的存在下，利用胺化合物所為之還原反應將甲酸銀(I)中所含的銀陽離子還原為銀原子，藉此形成表面被胺化合物及單元羧酸被覆而成之平均粒徑5~20nm之銀奈米粒子。[Steps a and b] Steps a and b are carried out in the present invention. a) Formic acid is allowed to act on the powdered silver oxide (I) in a hydrocarbon solvent to convert the powdery silver (I) oxide into silver formate (I). b) in the above hydrocarbon solvent, in the presence of a carboxylic acid having 8 to 11 carbon atoms, the silver cation contained in the silver formate (I) is reduced to a silver atom by a reduction reaction of the amine compound, thereby forming a surface A silver nanoparticle having an average particle diameter of 5 to 20 nm which is coated with an amine compound and a unit carboxylic acid.

使用1級胺(R^a -NH₂ )與2級胺(R^b R^c -NH)兩者作為步驟b所使用的胺化合物。Both the amine of the first order (R ^a -NH ₂ ) and the amine of the second order (R ^b R ^c -NH) are used as the amine compound used in the step b.

單元羧酸的添加時間為步驟a及b之任意時間即可。例如：可在步驟a中，將單元羧酸混合於烴溶劑中，而於其後添加甲酸。或在步驟a不使用單元羧酸，而在步驟b中，添加胺化合物同時添加單元羧酸亦可。The addition time of the unit carboxylic acid may be any time of steps a and b. For example, in step a, the unit carboxylic acid may be mixed in a hydrocarbon solvent, and then formic acid is added. Alternatively, the unit carboxylic acid is not used in the step a, and in the step b, the addition of the amine compound while adding the unit carboxylic acid may be carried out.

從步驟b可獲得單元羧酸及胺化合物(尤其是1級胺)透過配位性鍵結而鍵結於表面以形成被覆層之銀奈米粒子。From step b, it is possible to obtain a silver silicate particle in which a unit carboxylic acid and an amine compound (especially a primary amine) are bonded to the surface via a coordination bond to form a coating layer.

步驟b可接續於步驟a，而在步驟a所使用的烴溶劑中實施。因此，可藉由在得自於步驟a之反應液中添加前述單元羧酸與胺化合物(1級胺及2級胺)，並因應需要進行攪拌來實施步驟b。Step b can be carried out in step a, but in the hydrocarbon solvent used in step a. Therefore, step b can be carried out by adding the above-mentioned unit carboxylic acid and an amine compound (a primary amine and a secondary amine) to the reaction liquid obtained in the step a, and stirring as necessary.

在步驟b中，亦可追加和步驟a所使用之相同的烴溶劑。藉此，可用烴溶劑稀釋胺化合物並調整胺化合物的濃度。例如也可就粉末狀氧化銀(I)每100質量份，追加50質量份以上150質量份以下之烴溶劑來調節(稀釋)胺化合物的濃度。In the step b, the same hydrocarbon solvent as that used in the step a may be added. Thereby, the amine compound can be diluted with a hydrocarbon solvent and the concentration of the amine compound can be adjusted. For example, the concentration of the amine compound may be adjusted (diluted) by adding 50 parts by mass or more to 150 parts by mass or less of the hydrocarbon solvent per 100 parts by mass of the powdery silver oxide (I).

藉由實施步驟a及b，可在烴溶劑中調製銀奈米粒子。Silver nanoparticles can be prepared in a hydrocarbon solvent by carrying out steps a and b.

於步驟a及b之後，可因應需要從烴溶劑分離銀奈米粒子。為了分離可使用適當的方法。例如，可在減壓下使烴溶劑氣化而去除並獲得銀奈米粒子(不含烴溶劑的狀態)(參照步驟c)。After steps a and b, the silver nanoparticles can be separated from the hydrocarbon solvent as needed. A suitable method can be used for the separation. For example, the hydrocarbon solvent can be vaporized under reduced pressure to remove and obtain silver nanoparticles (state without a hydrocarbon solvent) (refer to step c).

[步驟a及b所使用的烴溶劑] 烴溶劑係通常不具極性或極性非常低之非極性溶劑。烴溶劑被利用作為粉末狀氧化銀(I)之分散介質，又，亦被利用作為溶解單元羧酸、胺化合物(1級胺與2級胺)之溶劑。[Hydrocarbon solvent used in steps a and b] The hydrocarbon solvent is a non-polar solvent which is usually not polar or has a very low polarity. The hydrocarbon solvent is used as a dispersion medium for the powdery silver oxide (I), and is also used as a solvent for the dissolution unit carboxylic acid, the amine compound (the primary amine and the secondary amine).

又，有時會有從反應液(包含步驟b所得到的銀奈米粒子之液體)分離銀奈米粒子並回收的情況，此時可藉由在減壓下進行餾去而將反應液所含的烴溶劑去除。因此，在減壓下會展現可餾去之蒸散性的烴溶劑較理想。又，亦可藉由在減壓下進行餾去而將2級胺去除。Further, the silver nanoparticles may be separated and recovered from the reaction liquid (the liquid containing the silver nanoparticles obtained in the step b), and the reaction liquid may be removed by distillation under reduced pressure. The hydrocarbon solvent contained is removed. Therefore, a hydrocarbon solvent which exhibits distillable vaporizability under reduced pressure is preferred. Further, the secondary amine can also be removed by distillation under reduced pressure.

此外，使用與甲酸之沸點(100.75℃)相同程度或較低沸點之烴溶劑的話，在反應液之液溫隨著甲酸銀(I)生成反應中的放熱而上昇時，液溫不會超過烴溶劑的沸點，故可抑制甲酸的蒸散。In addition, when a hydrocarbon solvent having the same degree or lower boiling point as that of formic acid (100.75 ° C) is used, the liquid temperature does not exceed the hydrocarbon when the liquid temperature of the reaction liquid rises with the exotherm in the formation reaction of silver formate (I). The boiling point of the solvent inhibits the evapotranspiration of formic acid.

考慮如上述的點，烴溶劑宜為碳數6~9之直鏈烷或碳數6~9之環烷。烴溶劑之沸點宜為65℃~155℃，為80℃~130℃更佳，為80℃~101℃再更佳。In view of the above, the hydrocarbon solvent is preferably a linear alkane having a carbon number of 6 to 9 or a cycloalkane having a carbon number of 6 to 9. The boiling point of the hydrocarbon solvent is preferably from 65 ° C to 155 ° C, more preferably from 80 ° C to 130 ° C, even more preferably from 80 ° C to 101 ° C.

作為烴溶劑之例子，可列舉：甲基環己烷(沸點101℃)、庚烷(沸點98.42℃)。Examples of the hydrocarbon solvent include methylcyclohexane (boiling point 101 ° C) and heptane (boiling point 98.42 ° C).

又，考慮防止甲酸銀(I)生成反應之放熱所導致反應液溫上昇的觀點，在步驟a中，就粉末狀氧化銀(I)每100質量份，使用烴溶劑400質量份以上700質量份以下較理想。Further, in view of the viewpoint of preventing the temperature of the reaction liquid from rising due to the exothermic heat of the silver formic acid (I) formation reaction, in the step a, 400 parts by mass or more and 700 parts by mass of the hydrocarbon solvent are used per 100 parts by mass of the powdery silver oxide (I). The following is ideal.

[粉末狀氧化銀(I)] 使用粉末狀氧化銀(I)(Ag₂ O，化學式量231.74，密度7.22g/cm³ )作為初始原料。粉末狀氧化銀(I)的粒徑可適當地選擇，但考慮均勻地分散於烴溶劑的觀點，宜使用粉末狀氧化銀(I)之粒徑分佈落在200網目以下(75μm以下)之範圍者。[Powdered Silver Oxide (I)] Powdered silver oxide (I) (Ag ₂ O, chemical formula: 231.74, density 7.22 g/cm ³ ) was used as a starting material. The particle size of the powdery silver oxide (I) can be appropriately selected. However, in view of uniform dispersion in a hydrocarbon solvent, it is preferred to use a powdery silver oxide (I) whose particle size distribution falls within a range of 200 mesh or less (75 μm or less). By.

[甲酸銀(I)之生成] 在步驟a係於烴溶劑中，使甲酸(HCOOH)作用於粉末狀氧化銀(I)而將粉末狀氧化銀(I)轉化為甲酸銀(I)。為此，可在烴溶劑中添加粉末狀氧化銀(I)後使其分散並於該分散液中添加甲酸。反應時可實施適當地攪拌。[Production of silver formate (I)] In step a, a hydrocarbon solvent is used to convert formic acid (HCOOH) to powdery silver oxide (I) to convert silvery silver (I) into silver formate (I). To this end, powdery silver oxide (I) may be added to a hydrocarbon solvent, dispersed, and formic acid may be added to the dispersion. Appropriate stirring can be carried out during the reaction.

甲酸會利用氫鍵而締合形成二聚物(HCOOH：HOOCH)。在烴溶劑中，其大多亦以形成二聚物的狀態分散。因此，甲酸之二聚物作用於分散液中的粉末狀氧化銀(I)，並利用下式i所表示之反應生成甲酸銀(I)(HCOOAg)。Formic acid associates with a hydrogen bond to form a dimer (HCOOH: HOOCH). In the hydrocarbon solvent, most of them are also dispersed in a state in which a dimer is formed. Therefore, the dimer of formic acid acts on the powdery silver oxide (I) in the dispersion, and the reaction represented by the following formula i is used to form silver formate (I) (HCOOAg).

式i： Ag^I ₂ O+(HCOOH：HOOCH)→2[(HCOO^- )(Ag^I )⁺ ]+H₂ O 另外據推斷：於式i之反應所副生成的大部分水分子(H₂ O)係以「結晶水」的形態而被捕捉到所生成的[(HCOO^- )(Ag^I )⁺ ]之凝聚體中。Formula i: Ag ^I ₂ O+(HCOOH:HOOCH)→2[(HCOO ^- )(Ag ^I ) ⁺ ]+H ₂ O It is also inferred that most of the water molecules (H ₂ O) formed by the reaction of the formula i ) is captured in the form of "crystal water" and is formed in the aggregate of [(HCOO ^- )(Ag ^I ) ⁺ ]).

上述式i所表示之反應相當於鹼性金屬氧化物之氧化銀(I)與甲酸之二聚物的「中和反應」，係為放熱反應。藉由將相對於粉末狀氧化銀(I)之烴溶劑量的比率選擇在前述範圍(就粉末狀氧化銀(I)每100質量份，為400質量份以上700質量份以下)，而易於將反應液之溫度上昇抑制在約40℃為止。亦即，藉由抑制液溫的上昇，而易於抑制副反應。就副反應而言有：能以下式A1所表示之還原反應、或能以下式A2表示之所生成的甲酸銀(I)本身的分解性還原反應。The reaction represented by the above formula i corresponds to the "neutralization reaction" of the silver oxide (I) of the basic metal oxide and the dimer of the formic acid, and is an exothermic reaction. By selecting the ratio of the amount of the hydrocarbon solvent to the powdery silver oxide (I) in the above range (400 parts by mass or more and 700 parts by mass or less per 100 parts by mass of the powdery silver oxide (I)), it is easy to The temperature rise of the reaction liquid was suppressed to about 40 °C. That is, by suppressing an increase in the liquid temperature, it is easy to suppress side reactions. The side reaction may be a reduction reaction represented by the following formula A1 or a decomposable reduction reaction of silver formate (I) which can be produced by the following formula A2.

式A1： 2[(HCOO^- )(Ag^I )⁺ ]+HCOOH→2Ag+2HCOOH+CO₂ ↑， 式A2： 2[(HCOO^- )(Ag^I )⁺ ]→2Ag+HCOOH+CO₂ ↑。Formula A1: 2[(HCOO ^- )(Ag ^I ) ⁺ ]+HCOOH→2Ag+2HCOOH+CO ₂ ↑, Formula A2: 2[(HCOO ^- )(Ag ^I ) ⁺ ]→2Ag+HCOOH+CO ₂ ↑.

為了實施上述式i之反應，就原料之粉末狀氧化銀(I)中所含的銀陽離子每1莫耳，甲酸宜在1.02莫耳~1.4莫耳之範圍內使用，在1.05莫耳~1.2莫耳之範圍內使用更佳。藉由添加過量的甲酸，可將原料之粉末狀氧化銀(I)的全部量轉化為甲酸銀(I)。In order to carry out the reaction of the above formula i, the silver cation contained in the powdery silver oxide (I) of the raw material is used in a range of 1.02 mol to 1.4 mol per 1 mol of the silver cation, and is 1.05 mol to 1.2 m. It is better to use within the range of Moore. The entire amount of the powdery silver oxide (I) of the raw material can be converted into silver formate (I) by adding an excess amount of formic acid.

添加過量的甲酸時，未反應的甲酸會殘餘，並以甲酸之二聚物的形式分散於烴溶劑中。When an excessive amount of formic acid is added, unreacted formic acid remains and is dispersed in a hydrocarbon solvent in the form of a dimer of formic acid.

[胺化合物所為之還原反應] 在步驟a之後，繼續在前述烴溶劑中，於碳數8~11之單元羧酸的存在下，利用胺化合物(1級胺及2級胺)所為之還原反應將甲酸銀(I)中所含的銀陽離子還原為銀原子。藉此形成表面被單元羧酸及胺化合物被覆而成的銀奈米粒子。[Reduction reaction by the amine compound] After the step a, the reduction reaction is carried out by using an amine compound (a primary amine and a secondary amine) in the presence of a hydrocarbon having 8 to 11 carbon atoms in the above hydrocarbon solvent. The silver cation contained in the silver formate (I) is reduced to a silver atom. Thereby, silver nanoparticles having a surface covered with a unit carboxylic acid and an amine compound are formed.

具體而言，可在得自於步驟a的反應液之溫度下降到30℃之時間點，將碳數8~11之單元羧酸與胺化合物(1級胺(NH₂ -R^a )與2級胺(NH-R^b R^c ))添加至得自於步驟a之液體較理想。Specifically, the unit carboxylic acid having a carbon number of 8 to 11 and the amine compound (the amine of the first order (NH ₂ -R ^a ) and 2 can be obtained at a time point when the temperature of the reaction liquid obtained in the step a is lowered to 30 ° C. The addition of the amine (NH-R ^b R ^c )) to the liquid from step a is preferred.

藉此會生成甲酸銀(I)之胺錯合物，亦即1級胺錯合物(HCOOAg：NH₂ -R^a )及2級胺錯合物(HCOOAg：NH-R^b R^c )。Thereby, an amine complex of silver (I) formic acid, that is, a grade 1 amine complex (HCOOAg: NH ₂ -R ^a ) and a grade 2 amine complex (HCOOAg: NH-R ^b R ^c ) are formed.

據推斷：在胺錯合物生成時，甲酸銀(I)之凝聚體中，亦即[(HCOO^- )(Ag^I )⁺ ]之凝聚體中，以「結晶水」的形態被捕捉之水分子會與胺錯合物之甲酸陰離子種(^- O-CHO)的部分成為「溶劑化(solvation)」之狀態。因此據推斷：最終生成的甲酸銀(I)之胺錯合物係因上述水分子(H₂ O)為「溶劑化」之狀態而溶解於烴溶劑中。It is estimated that in the formation of an amine complex, water in the form of "crystal water" in the aggregate of [(HCOO ^- )(Ag ^I ) ⁺ ] in the aggregate of silver formate (I) molecules and complexes of ammonium formate anion species ^- part (O-CHO) becomes "solvated (and solvation)" of the state. Therefore, it is estimated that the finally formed amine complex of silver formate (I) is dissolved in a hydrocarbon solvent because the water molecule (H ₂ O) is "solvated".

未反應的甲酸殘餘在得自於步驟a之反應液中時，在得自於步驟a之反應液中添加前述胺化合物的話，胺化合物會與殘餘的甲酸反應，並生成甲酸之胺加成鹽(HCOOH：NH₂ -R^a 、HCOOH：NH-R^b R^c )。甲酸之胺加成鹽形成反應相當於酸、鹼之「中和反應」，係為放熱反應。因此，隨著此反應的進行，反應液之溫度會上昇。另外，反應液之溫度若接近所使用的烴溶劑之沸點的話，烴溶劑之蒸散就會開始，故反應液之溫度不超過烴溶劑之沸點。When the unreacted formic acid residue is obtained from the reaction liquid of the step a, when the amine compound is added to the reaction liquid obtained from the step a, the amine compound is reacted with the residual formic acid to form an amine addition salt of formic acid. (HCOOH: NH ₂ -R ^a , HCOOH: NH-R ^b R ^c ). The amine acid addition salt formation reaction of formic acid corresponds to a "neutralization reaction" of an acid or a base, and is an exothermic reaction. Therefore, as the reaction progresses, the temperature of the reaction liquid rises. Further, if the temperature of the reaction liquid is close to the boiling point of the hydrocarbon solvent to be used, the evapotranspiration of the hydrocarbon solvent starts, so that the temperature of the reaction liquid does not exceed the boiling point of the hydrocarbon solvent.

液溫例如上昇至約55℃~65℃的話，甲酸銀(I)之胺錯合物(1級胺錯合物及2級胺錯合物)就會開始下式ii或iii所表示之分解性還原反應。When the liquid temperature rises, for example, to about 55 ° C to 65 ° C, the amine complex of silver (I) formic acid (the first-order amine complex and the second-order amine complex) starts decomposition as represented by the following formula ii or iii. Sexual reduction reaction.

式ii： 2(R^a -NH₂ ：Ag-OOCH)→2[R^a -NH₂ ：Ag]+HCOOH+CO₂ ↑， 式iii： 2(R^b R^c -NH：Ag-OOCH)→2[R^b R^c -NH：Ag]+HCOOH+CO₂ ↑。Formula ii: 2(R ^a -NH ₂ :Ag-OOCH)→2[R ^a -NH ₂ :Ag]+HCOOH+CO ₂ ↑, Formula iii: 2(R ^b R ^c -NH:Ag-OOCH)→ 2[R ^b R ^c -NH:Ag]+HCOOH+CO ₂ ↑.

在此反應產生的二氧化碳(CO₂ )會形成氣泡，故於反應液會觀測到起泡。The carbon dioxide (CO ₂ ) generated in this reaction forms bubbles, so foaming is observed in the reaction liquid.

又，副生成的甲酸有時會先形成甲酸之二聚物，然後與溶解於反應液中的胺化合物反應生成甲酸之胺加成鹽。Further, the by-produced formic acid may first form a dimer of formic acid, and then react with an amine compound dissolved in the reaction liquid to form an amine addition salt of formic acid.

另一方面，分解性還原反應所生成的金屬銀原子[Ag：NH₂ -R^a ]及[Ag：NH-R^b R^c ]會凝聚而構成金屬銀原子之凝聚體。此時，隨著金屬銀原子之凝聚體的形成，配位於金屬銀原子之1級胺(R^a -NH₂ )及2級胺(R^b R^c -NH)之一部分會熱解離。因此，形成的金屬銀原子之凝聚體成為以由金屬原子構成的球狀核、與由被覆於該核的表面之胺化合物(1級胺(R^a -NH₂ ))構成的被覆劑分子層構成之銀奈米粒子。On the other hand, the metal silver atoms [Ag:NH ₂ -R ^a ] and [Ag:NH-R ^b R ^c ] produced by the decomposing reduction reaction are aggregated to form an aggregate of metal silver atoms. At this time, as agglomerates of metal silver atoms are formed, a part of the amine (R ^a -NH ₂ ) and the second amine (R ^b R ^c -NH) which are coordinated to the metal silver atom are thermally dissociated. Therefore, the aggregate of the formed metal silver atoms is a coating molecule layer composed of a spherical core composed of a metal atom and an amine compound (a grade amine (R ^a -NH ₂ )) coated on the surface of the core. Silver nanoparticle particles.

熱解離而成的胺(R^a -NH₂ 及R^b R^c -NH)亦涉及甲酸銀(I)之胺錯合物(HCOOAg：NH₂ -R^a 及HCOOAg：NH-R^b R^c )的生成反應及甲酸之胺加成鹽形成反應。The thermally dissociated amines (R ^a -NH ₂ and R ^b R ^c -NH) also relate to the amine complex of silver (I) formate (HCOOAg: NH ₂ -R ^a and HCOOAg: NH-R ^b R ^c ) The formation reaction and the amine addition salt formation reaction of formic acid.

藉由調節在步驟a結束的時點所殘餘的未反應之甲酸量、添加的胺化合物量、以及整體反應液量，可防止在步驟b中反應液的液溫上昇至70℃以上。By adjusting the amount of unreacted formic acid remaining at the time point of the completion of the step a, the amount of the amine compound to be added, and the amount of the entire reaction liquid, it is possible to prevent the liquid temperature of the reaction liquid from rising to 70 ° C or higher in the step b.

在步驟b中，若反應液中存在過量的胺化合物，則甲酸之胺加成鹽形成反應會進行，故溶解的甲酸之濃度會維持在低的水平。因此，可防止具有還原劑之功能的甲酸作用而防止上述式A1表示之還原反應(副反應)進行。In the step b, if an excessive amount of the amine compound is present in the reaction liquid, the amine addition salt formation reaction of the formic acid proceeds, so that the concentration of the dissolved formic acid is maintained at a low level. Therefore, the action of formic acid having a function as a reducing agent can be prevented to prevent the reduction reaction (side reaction) represented by the above formula A1 from proceeding.

又，若防止在步驟b中反應液的液溫上昇至70℃以上，則易於使甲酸銀(I)之胺錯合物的生成反應優先地進行，並易於抑制副反應即甲酸銀(I)本身之分解性反應的進行。In addition, when the liquid temperature of the reaction liquid is raised to 70 ° C or higher in step b, the formation reaction of the amine complex of silver formate (I) is easily carried out preferentially, and silver (I) which is a side reaction is easily suppressed. The decomposition of itself is carried out.

[1級胺] 考慮銀奈米粒子之調製容易性的觀點，1級胺的分子量為120以上200以下較理想。使用分子量為200以下之1級胺來調製銀奈米粒子的話，使用該粒子而利用作為導電性糊劑時，在煅燒處理時1級胺容易從銀脫離及分解，考慮導電特性的觀點較理想。另一方面，使用分子量為120以上之1級胺來製作銀奈米粒子的話，容易製得安定的銀奈米粒子。具體而言，容易避免在製作粒子時發生反應容器側面之鏡面化(銀的析出)等的現象。[I. Amine] From the viewpoint of ease of preparation of silver nanoparticles, the molecular weight of the first-grade amine is preferably 120 or more and 200 or less. When the silver nanoparticles are prepared by using the primary amine having a molecular weight of 200 or less, when the particles are used as the conductive paste, the primary amine is easily detached from the silver and decomposed during the calcination treatment, and the conductive property is preferable. . On the other hand, when silver nanoparticle is produced using a primary amine having a molecular weight of 120 or more, it is easy to obtain stable silver nanoparticle. Specifically, it is easy to avoid a phenomenon in which the side surface of the reaction container is mirror-finished (precipitation of silver) when the particles are produced.

考慮銀奈米粒子之分散性的觀點，1級胺具有對前述烴溶劑有親和性之脂肪族烴鏈較理想。亦即，構成1級胺(R^a -NH₂ )之原子團(氫以外之鍵結於氮原子的原子團)R^a 含有對前述烴溶劑具有親和性之脂肪族烴鏈較理想。R^a 含有對前述烴溶劑具有親和性之脂肪族烴鏈的話，調製而成的銀奈米粒子容易安定地分散在前述烴溶劑中。具體而言可使用分子內具有9以上11以下之碳原子的1級胺(R^a -NH₂ )。又，考慮將導電性糊劑以約120℃之低溫燒結時的燒結體之導電性的觀點，使用分子內具有11以下之碳原子的1級胺較理想。From the viewpoint of dispersibility of the silver nanoparticle, the primary amine has an aliphatic hydrocarbon chain having affinity for the hydrocarbon solvent. That is, the atomic group constituting the primary amine (R ^a -NH ₂ ) (an atomic group bonded to the nitrogen atom other than hydrogen) R ^a preferably contains an aliphatic hydrocarbon chain having affinity for the hydrocarbon solvent. When R ^a contains an aliphatic hydrocarbon chain having an affinity for the hydrocarbon solvent, the prepared silver nanoparticles are easily and stably dispersed in the hydrocarbon solvent. Specifically, a primary amine (R ^a -NH ₂ ) having 9 or more and 11 or less carbon atoms in the molecule can be used. Further, from the viewpoint of the conductivity of the sintered body when the conductive paste is sintered at a low temperature of about 120 ° C, it is preferred to use a primary amine having 11 or less carbon atoms in the molecule.

考慮該等觀點，可列舉：3-(2-乙基己氧基)丙胺、二丁胺基丙胺、癸胺等(該等1級胺對烴系溶劑具有親和性)作為理想的1級胺。In view of such viewpoints, 3-(2-ethylhexyloxy)propylamine, dibutylaminopropylamine, decylamine, and the like (these amines have affinity for a hydrocarbon solvent) are preferable as the primary amine. .

[2級胺] 考慮銀奈米粒子製作時的反應性之觀點，2級胺的分子量為100以上150以下較理想。分子量為150以下之2級胺就還原力的觀點較理想，容易使反應進行。又，考慮沸點的觀點分子量100以上的胺較理想，易於防止在反應中快速蒸散。[2-Amine] From the viewpoint of reactivity in the production of silver nanoparticles, the molecular weight of the secondary amine is preferably 100 or more and 150 or less. The second-order amine having a molecular weight of 150 or less is preferable from the viewpoint of reducing power, and it is easy to carry out the reaction. Further, in view of the boiling point, an amine having a molecular weight of 100 or more is preferable, and it is easy to prevent rapid evapotranspiration in the reaction.

又，考慮銀奈米粒子之分散性的觀點，2級胺具有對前述烴溶劑有親和性之脂肪族烴鏈較理想。亦即，構成2級胺(R^b R^c -NH)之原子團(氫以外之鍵結於氮原子的原子團)R^b 及R^c 中之一者或兩者含有對前述烴溶劑具有親和性之脂肪族烴鏈較理想。R^b 及R^c 中之一者或兩者含有對前述烴溶劑具有親和性之脂肪族烴鏈的話，調製而成的銀奈米粒子容易安定地分散在前述烴溶劑中。具體而言，使用分子內具有6以上12以下之碳原子的2級胺(R^b R^c -NH)較理想。Further, from the viewpoint of the dispersibility of the silver nanoparticles, the secondary amine has an aliphatic hydrocarbon chain having an affinity for the hydrocarbon solvent. That is, one or both of the atomic groups constituting the second-order amine (R ^b R ^c —NH) (the atomic group bonded to the nitrogen atom other than hydrogen) R ^b and R ^c have an affinity for the aforementioned hydrocarbon solvent. Aliphatic hydrocarbon chains are preferred. When one or both of R ^b and R ^c contain an aliphatic hydrocarbon chain having an affinity for the hydrocarbon solvent, the prepared silver nanoparticles are easily and stably dispersed in the hydrocarbon solvent. Specifically, a secondary amine (R ^b R ^c -NH) having 6 or more and 12 or less carbon atoms in the molecule is preferably used.

作為如此的2級胺之例子，可列舉：二丙胺、二異丙胺、甲基己胺、二丁胺、二異丁胺等。Examples of such a secondary amine include dipropylamine, diisopropylamine, methylhexylamine, dibutylamine, diisobutylamine and the like.

[碳數8~11之單元羧酸] 在步驟b中使用碳數為11以下之單元羧酸來調製銀奈米粒子的話，使用該粒子而利用作為導電性糊劑時，在煅燒處理時單元羧酸容易從銀脫離及分解，考慮導電特性的觀點較理想。另一方面，使用碳數為8以上之單元羧酸來製作銀奈米粒子的話，除了被覆於銀奈米粒子之1級胺外，單元羧酸亦被覆於銀奈米粒子，故立體地抑制銀奈米粒子彼此之接觸，容易製得安定的銀奈米粒子。[Cational carboxylic acid having a carbon number of 8 to 11] When silver nanoparticle is prepared by using a unit carboxylic acid having a carbon number of 11 or less in step b, when the particle is used as a conductive paste, the unit is used in the calcination treatment. The carboxylic acid is easily detached from the silver and decomposed, and the viewpoint of the conductive property is preferable. On the other hand, when a silver nanoparticle is produced using a unit carboxylic acid having a carbon number of 8 or more, the unit carboxylic acid is coated on the silver nanoparticle in addition to the primary amine coated with the silver nanoparticle, so that the three-dimensional suppression is performed. The silver nanoparticles are in contact with each other, and it is easy to produce stable silver nanoparticles.

[步驟b所使用的單元羧酸及胺化合物的量] 在步驟b中，碳數8~11之單元羧酸、1級胺及2級胺的量各別使用如下的量較理想。 碳數8~11之單元羧酸：就甲酸銀(I)所含的銀陽離子每1莫耳量，使用0.05莫耳量~0.3莫耳量。 1級胺：就甲酸銀(I)所含的銀陽離子每1莫耳量，使用0.05莫耳量~0.3莫耳量。 2級胺：就甲酸銀(I)所含的銀陽離子每1莫耳量，使用2級胺以使1級胺與2級胺之總莫耳量成為1.1莫耳量~1.5莫耳量之範圍。[Amount of the unit carboxylic acid and the amine compound used in the step b] In the step b, the amounts of the unit carboxylic acid having a carbon number of 8 to 11, the first-grade amine and the second-grade amine are preferably the following amounts. The unit carboxylic acid having a carbon number of 8 to 11 is used in an amount of 0.05 moles to 0.3 moles per 1 mole of the silver cation contained in the silver formate (I). Grade 1 amine: 0.05 moles to 0.3 moles per mole of silver cations contained in silver formate (I). Grade 2 amine: For every 1 mole of silver cation contained in silver formate (I), use a grade 2 amine to make the total mole amount of the grade 1 amine and the grade 2 amine 1.1 moles to 1.5 moles. range.

考慮形成表面被單元羧酸及胺化合物被覆而成的銀奈米粒子的觀點，選擇如此之用量上的平衡較理想。In view of the formation of silver nanoparticles having a surface coated with a unit carboxylic acid and an amine compound, it is preferable to select such a balance in the amount.

[步驟c~e] 接續於步驟a及b，可按順序實施步驟c~e。藉此可獲得銀奈米粒子分散於某烴溶劑(步驟e所使用的烴溶劑)中之分散液。 c) 在減壓下使前述烴溶劑氣化而從得自於步驟b之反應液去除，藉此回收含有前述銀奈米粒子之殘渣。 d) 以醇清洗該殘渣。 e) 使在步驟d清洗後的殘渣分散於和前述烴溶劑相同或不同的烴溶劑中而獲得銀奈米粒子分散液。[Steps c~e] Following steps a and b, steps c~e can be performed in sequence. Thereby, a dispersion in which silver nanoparticles are dispersed in a hydrocarbon solvent (hydrocarbon solvent used in step e) can be obtained. c) The hydrocarbon solvent is vaporized under reduced pressure to be removed from the reaction liquid obtained in the step b, whereby the residue containing the silver nanoparticles is recovered. d) Wash the residue with alcohol. e) The residue after washing in the step d is dispersed in a hydrocarbon solvent which is the same as or different from the hydrocarbon solvent to obtain a silver nanoparticle dispersion.

於步驟c中，係在減壓下使步驟a及b所使用的烴溶劑氣化而去除。同時可使2級胺氣化而去除。此操作例如可適當地實施使用蒸發器之方法等公知的方法。例如，於液溫40℃利用蒸發器使容器內的壓力降低至約50hPa以下而去除烴溶劑及2級胺。In the step c, the hydrocarbon solvent used in the steps a and b is vaporized and removed under reduced pressure. At the same time, the second-grade amine can be gasified and removed. For this operation, for example, a known method such as a method using an evaporator can be suitably carried out. For example, the hydrocarbon solvent and the secondary amine are removed by lowering the pressure in the vessel to about 50 hPa or less at a liquid temperature of 40 ° C using an evaporator.

步驟d所使用的醇可列舉例如：甲醇、乙醇、1-丙醇、2-丙醇、1-丁醇、2-丁醇、2-甲基-1-丙醇。其中，尤其考慮極性高且在後續步驟中的去除之容易性的觀點，可適當地使用甲醇。在以下之步驟d的說明中記載了甲醇作為醇的一例。The alcohol used in the step d may, for example, be methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol or 2-methyl-1-propanol. Among them, methanol is suitably used from the viewpoint of high polarity and ease of removal in subsequent steps. In the description of the following step d, methanol is described as an example of an alcohol.

在步驟d中，可採用以甲醇清洗微粒之公知的方法。例如藉由在得自於步驟c之殘渣中添加甲醇並攪拌後，利用傾析法移除甲醇，可實質上地將甲醇從殘渣去除。此時相當於多餘的甲酸、胺化合物、或含有該等之鹽等之成分的量會溶解於甲醇，藉此而實施銀奈米粒子的清洗。為了有效率地實施清洗，就作為原料而使用的粉末狀氧化銀(I)每100質量份，使用500質量份以上1000質量份以下的甲醇，並分成2次以上4次以下之次數進行清洗較理想。In the step d, a known method of washing the particles with methanol can be employed. For example, by adding methanol to the residue obtained in the step c and stirring, the methanol is removed by decantation to substantially remove the methanol from the residue. At this time, the amount of excess formic acid, an amine compound, or a component containing the salt or the like is dissolved in methanol, whereby the silver nanoparticles are washed. In order to carry out the cleaning efficiently, the powdery silver oxide (I) used as a raw material is used in an amount of 500 parts by mass or more and 1000 parts by mass or less per 100 parts by mass, and is divided into two or more times and four times or less. ideal.

步驟e所使用的烴溶劑可為與步驟a及b所使用的烴溶劑相同的種類，亦可為不同的種類。就此烴溶劑而言，可使用先前於[步驟a及b所使用的烴溶劑]中所述之烴溶劑。就作為原料而使用之粉末狀氧化銀(I)每100質量份，使銀奈米粒子分散於100質量份以上300質量份以下之烴溶劑中較理想。獲得的銀奈米粒子係以單元羧酸及具有烴鏈之胺化合物被覆而成的銀奈米粒子，故藉由於步驟e中使用烴溶劑，可獲得均勻地分散於烴溶劑中之銀奈米粒子。The hydrocarbon solvent used in the step e may be the same type as the hydrocarbon solvent used in the steps a and b, or may be a different type. For the hydrocarbon solvent, the hydrocarbon solvent previously described in [hydrocarbon solvent used in steps a and b] can be used. It is preferable to disperse the silver nanoparticles in 100 parts by mass or more and 300 parts by mass or less of the hydrocarbon solvent per 100 parts by mass of the powdery silver oxide (I) used as the raw material. The obtained silver nanoparticle is a silver nanoparticle coated with a unit carboxylic acid and an amine compound having a hydrocarbon chain. Therefore, by using a hydrocarbon solvent in the step e, silver nanoparticles uniformly dispersed in a hydrocarbon solvent can be obtained. particle.

因應銀奈米粒子之用途，可將得自於步驟e之分散液直接作為印墨等之原料使用。尤其，依下述程序可調製導電性糊劑，尤其是印刷用之導電性糊劑。In view of the use of the silver nanoparticle, the dispersion obtained in the step e can be directly used as a raw material of ink or the like. In particular, a conductive paste, particularly a conductive paste for printing, can be prepared according to the following procedure.

作為在步驟e中使殘渣(甲醇清洗後)再分散之分散溶劑，宜使用沸點65℃~155℃之範圍的烴溶劑。因應需要，宜藉由在步驟e之後將步驟e所得到的分散液之烴溶劑取代為沸點180℃~355℃之範圍的高沸點烴溶劑，取代為沸點200℃~310℃之範圍的高沸點烴溶劑更佳，取代為沸點220℃~310℃之範圍的高沸點烴溶劑再更佳，而可調製導電性糊劑。As the dispersion solvent for redispersing the residue (after methanol washing) in the step e, a hydrocarbon solvent having a boiling point of from 65 ° C to 155 ° C is preferably used. If necessary, it is preferable to replace the high boiling point hydrocarbon solvent having a boiling point of 180 ° C to 355 ° C by the hydrocarbon solvent of the dispersion obtained in the step e after the step e, and to replace the high boiling point in the range of the boiling point of 200 ° C to 310 ° C. The hydrocarbon solvent is more preferable, and a high-boiling hydrocarbon solvent having a boiling point of from 220 ° C to 310 ° C is more preferably substituted, and a conductive paste can be prepared.

或依情況可使用前述高沸點烴溶劑作為在步驟e中使殘渣(甲醇清洗後)分散之分散溶劑。此時，可從步驟e直接獲得導電性糊劑。Alternatively, the above-mentioned high-boiling hydrocarbon solvent may be used as the dispersion solvent in which the residue (after methanol washing) is dispersed in the step e. At this time, the conductive paste can be directly obtained from the step e.

作為可使用的高沸點烴溶劑之例子可列舉：為十四烷(沸點253.6℃)等之碳數12~16之範圍的烷、或環烷/石蠟系烴之混合溶劑即JX日礦日石能源製之AF SOLVENT(商品名)、NAPHTESOL(商品名)等。又，亦可舉例出光興產製之IP SOLVENT(商品名)。又，亦可利用多種高沸點烴溶劑之混合物。Examples of the high-boiling hydrocarbon solvent that can be used include an alkane having a carbon number of 12 to 16 such as tetradecane (boiling point: 253.6 ° C) or a mixed solvent of a naphthenic/paraffin-based hydrocarbon, that is, JX Nippon Rock. Energy system AF SOLVENT (trade name), NAPHTESOL (trade name), etc. In addition, IP SOLVENT (trade name) of the Hiroshi Production System can also be exemplified. Further, a mixture of a plurality of high boiling hydrocarbon solvents can also be utilized.

可使用導電性糊劑以為印刷用印墨之用。作為印刷法之例子可列舉：噴墨印刷法、凹版反轉印刷、網版印刷法等。亦可適當地添加印刷用導電性糊劑所使用之公知的成分。A conductive paste can be used for printing inks. Examples of the printing method include an inkjet printing method, a gravure reverse printing, and a screen printing method. A well-known component used for the conductive paste for printing can also be added suitably.

在具有被覆層之銀奈米粒子中，考慮分散安定性的觀點，就銀每100質量份而言，被覆劑為10質量份以上較理想。又，考慮以低溫煅燒形成煅燒後為數微米以上的膜厚之膜的觀點，就銀每100質量份而言，被覆劑為22質量份以下較理想。 [實施例]In the silver nanoparticle having a coating layer, the coating agent is preferably used in an amount of 10 parts by mass or more per 100 parts by mass of the silver. In addition, it is preferable that the coating agent is 22 parts by mass or less per 100 parts by mass of silver, from the viewpoint of forming a film having a film thickness of several micrometers or more after firing at a low temperature. [Examples]

以下，根據實施例更詳細地說明本發明，但本發明並不限於此。Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

[實施例1] ･步驟a 使粉末狀氧化銀(I)(Ag₂ O，化學式量231.735)100質量份(0.43莫耳份)分散於甲基環己烷(沸點100.9℃，密度0.7737)550質量份。在室溫(25℃)攪拌下，歷時3~5分鐘滴加甲酸(HCOOH，化學式量46.03，沸點100.75℃)41.3質量份(0.90莫耳份)於所得到的分散液中。使其成為就氧化銀(I)之Ag每1莫耳添加有甲酸1.04莫耳量。在烴溶劑即甲基環己烷中生成甲酸銀。由於甲酸的添加，放熱反應會進行而液溫會上昇到約45℃。若粉末狀氧化銀轉化為甲酸銀的話，其後反應液之溫度會下降。[Example 1] - Step a Disperse 100 parts by mass (0.43 mole parts) of powdery silver oxide (I) (Ag ₂ O, chemical formula amount 231.75) in methylcyclohexane (boiling point 100.9 ° C, density 0.7737) 550 Parts by mass. 41.3 parts by mass (0.90 mole parts) of formic acid (HCOOH, chemical formula amount 46.03, boiling point 100.75 ° C) was added dropwise to the obtained dispersion over 3 to 5 minutes while stirring at room temperature (25 ° C). It was made to add 1.04 moles of formic acid per 1 mole of Ag for silver oxide (I). Silver formate is formed in a hydrocarbon solvent, methylcyclohexane. Due to the addition of formic acid, the exothermic reaction proceeds and the liquid temperature rises to about 45 °C. If the powdery silver oxide is converted to silver formate, the temperature of the reaction liquid thereafter decreases.

･步驟b 在得自於步驟a的反應液之溫度下降到27℃以下之時點，將新癸酸(C₁₀ H₂₀ O₂ ，化學式量172.26)18.4質量份添加至反應液中。使其成為就氧化銀(I)之Ag每1莫耳添加有新癸酸0.12莫耳量。In the step b, 18.4 parts by mass of neodecanoic acid (C ₁₀ H ₂₀ O ₂ , chemical formula: 172.26) was added to the reaction liquid when the temperature of the reaction liquid obtained in the step a was lowered to 27 ° C or lower. It is made to add 0.12 moles of neodecanoic acid per 1 mole of Ag for silver oxide (I).

然後於反應液中添加已將2-乙基己氧丙胺(C₁₁ H₂₅ NO，化學式量187.32，沸點235℃)23.1質量份與二異丙胺(C₆ H₁₅ N，化學式量101.19，沸點84℃)115.3質量份溶解於甲基環己烷92質量份而成的溶液。使其成為就初始原料之氧化銀(I)之Ag每1莫耳添加有2-乙基己氧丙胺0.14莫耳量、二異丙胺1.32莫耳量。Then, 23.1 parts by mass of 2-ethylhexyloxypropylamine (C ₁₁ H ₂₅ NO, chemical formula amount: 187.32, boiling point 235 ° C) and diisopropylamine (C ₆ H ₁₅ N, chemical formula amount 101.19, boiling point 84) were added to the reaction liquid. °C) 115.3 parts by mass of a solution obtained by dissolving 92 parts by mass of methylcyclohexane. Ag was added to the silver oxide (I) as a starting material, and 0.1 mol of 2-ethylhexyloxypropylamine and 1.32 mol of diisopropylamine were added per 1 mol of Ag.

因胺的添加所為之酸鹼的中和反應以致液溫會上昇到約65℃。隨著液溫的上昇，經由甲酸銀之胺錯合物，會發生甲酸銀之分解性還原反應。因還原反應而析出的銀奈米粒子受到系統內之1級胺(2-乙基己氧丙胺)及新癸酸保護，藉此會抑制銀奈米粒子的肥大化。反應液的顏色從甲酸銀呈懸浮之灰色的狀態，隨著因胺添加所致甲酸銀之溶解而變化為茶色，並伴隨起泡而變化成深藍色。液溫上昇到約65℃後，繼續反應液的攪拌，在液溫下降到45℃的時點停止攪拌。The neutralization reaction of the acid and base due to the addition of the amine causes the liquid temperature to rise to about 65 °C. As the liquid temperature rises, a decomposable reduction reaction of silver formate occurs via an amine complex of silver formate. The silver nanoparticles precipitated by the reduction reaction are protected by the primary amine (2-ethylhexyloxypropylamine) and neodecanoic acid in the system, thereby suppressing the enlargement of the silver nanoparticles. The color of the reaction liquid changed from a state in which the silver formate was suspended to a gray color, and changed to a brown color as the silver formate was dissolved by the addition of the amine, and changed to a deep blue color with foaming. After the liquid temperature rose to about 65 ° C, the stirring of the reaction liquid was continued, and the stirring was stopped when the liquid temperature was lowered to 45 ° C.

･步驟c(脫溶劑) 將得到的深藍色分散液移至茄形燒瓶，並於減壓下將反應溶劑之甲基環己烷、二異丙胺餾去。 在減壓下將溶劑等餾去時的溫度設定為40℃，減壓度從150hPa開始。邊確認溶劑等餾去的狀態，邊注意突沸並緩緩地提昇減壓度，最終達到60hPa。在60hPa進行脫溶劑的話，茄形燒瓶內之含銀奈米粒子的內容物因溶劑等被去除而變化為漿狀。溫度提昇至45℃再於減壓下實施約10min脫溶劑。- Step c (desolvation) The obtained dark blue dispersion was transferred to an eggplant-shaped flask, and methylcyclohexane and diisopropylamine of the reaction solvent were distilled off under reduced pressure. The temperature at which the solvent or the like was distilled off under reduced pressure was set to 40 ° C, and the degree of pressure reduction was started from 150 hPa. While confirming the state in which the solvent was distilled off, attention was paid to the boiling and the degree of pressure reduction was gradually increased to finally reach 60 hPa. When the solvent is removed at 60 hPa, the content of the silver-containing nanoparticles in the eggplant-shaped flask is removed by a solvent or the like to change into a slurry. The temperature was raised to 45 ° C and the solvent was removed under reduced pressure for about 10 minutes.

･步驟d(甲醇清洗) 於脫溶劑處理後之殘渣中添加甲醇(沸點64.7℃)280質量份、蒸餾水50質量份。- Step d (methanol cleaning) 280 parts by mass of methanol (boiling point: 64.7 ° C) and 50 parts by mass of distilled water were added to the residue after the solvent removal treatment.

脫溶劑處理後之殘渣中含有：表面被新癸酸及2-乙基己氧丙胺被覆之銀奈米粒子、甲酸或新癸酸之二異丙胺加成鹽、甲酸或新癸酸之2-乙基己氧丙胺加成鹽、殘留的甲基環己烷。甲酸或新癸酸之二異丙胺加成鹽、甲酸或新癸酸之2-乙基己氧丙胺加成鹽與甲基環己烷會溶解於由甲醇及蒸餾水構成的混合溶劑中。另一方面，銀奈米粒子不會分散於含水甲醇而會沉降。The residue after the solvent removal treatment comprises: silver nanoparticles coated with neodecanoic acid and 2-ethylhexyloxypropylamine, diisopropylamine addition salt of formic acid or neodecanoic acid, 2-carboxylic acid or neodecanoic acid Ethyl hexyloxypropylamine addition salt, residual methylcyclohexane. The diisopropylamine addition salt of formic acid or neodecanoic acid, the 2-ethylhexyloxypropylamine addition salt of formic acid or neodecanoic acid and methylcyclohexane are dissolved in a mixed solvent composed of methanol and distilled water. On the other hand, silver nanoparticles do not disperse in aqueous methanol and settle.

利用傾析法去除混合溶劑(含水甲醇)之上清相。The supernatant phase of the mixed solvent (aqueous methanol) was removed by decantation.

為了提高殘留成分之去除效率，於得自經傾析法之沉降相中再添加甲醇280質量份後攪拌並利用傾析法去除上清相。In order to increase the removal efficiency of the residual component, 280 parts by mass of methanol was further added to the sedimentation phase obtained by the decantation method, and the mixture was stirred and the supernatant phase was removed by decantation.

･步驟e(再分散到溶劑) 於得自經傾析法之沉降相中添加甲基環己烷120質量份。沉降而得的銀奈米粒子會分散於甲基環己烷。經沉降之銀粒子所殘存的甲醇因欠缺與甲基環己烷之相容性而相分離。將已相分離之甲醇相部分去除。- Step e (redistribution to solvent) 120 parts by mass of methylcyclohexane was added to the sedimentation phase obtained by the decantation method. The precipitated silver nanoparticles are dispersed in methylcyclohexane. The methanol remaining in the settled silver particles is phase-separated due to lack of compatibility with methylcyclohexane. The phase separated methanol phase is partially removed.

･純化步驟 分散有銀奈米粒子之甲基環己烷相中會有些許甲醇溶解並混入。於減壓下將混入的甲醇餾去。利用甲醇與甲基環己烷之沸點的差選擇性地將甲醇餾去。具體而言，於45℃(浴溫)在150hPa實施5min脫甲醇後，將減壓度提昇至120hPa，再實施3min脫甲醇。・Purification step Some of the methylcyclohexane phase in which silver nanoparticles are dispersed dissolves and mixes in methanol. The mixed methanol was distilled off under reduced pressure. The methanol was selectively distilled off using the difference in boiling points of methanol and methylcyclohexane. Specifically, after deamination at 45 ° C (bath temperature) at 150 hPa for 5 min, the degree of decompression was increased to 120 hPa, and methanol removal was carried out for 3 min.

將獲得的分散有銀奈米粒子之甲基環己烷液體以0.2μm濾膜過濾並將凝聚物去除。以得自經過濾的濾液之形式獲得銀奈米粒子分散液。The obtained methylcyclohexane liquid in which silver nanoparticles were dispersed was filtered through a 0.2 μm filter and the aggregate was removed. A silver nanoparticle dispersion was obtained in the form of a filtrate obtained from the filtration.

･評價 測量得到的銀奈米粒子分散液所含的金屬銀之總量，以初始原料之氧化銀(I)中所含的銀之含量作為基準算出產率。算出的產率為98%。・Evaluation The total amount of metallic silver contained in the silver nanoparticle dispersion obtained by the measurement was calculated, and the yield was calculated based on the content of silver contained in the silver oxide (I) of the starting material. The calculated yield was 98%.

金屬銀之總量的測量方法如下所述。將得到的銀奈米粒子分散液稱量於坩堝中，以熱風乾燥機將所含有的甲基環己烷乾燥去除獲得固體後，將坩堝放入灰化爐以700℃煅燒30min。因煅燒後僅金屬會殘存，故稱量金屬量並從分散液之濃度算出金屬銀之總量。The measurement method of the total amount of metallic silver is as follows. The obtained silver nanoparticle dispersion was weighed in a crucible, and the methylcyclohexane contained therein was dried by a hot air dryer to obtain a solid, and then the crucible was placed in an ashing furnace and calcined at 700 ° C for 30 minutes. Since only the metal remains after calcination, the amount of metal is weighed and the total amount of metallic silver is calculated from the concentration of the dispersion.

又，將得到的銀奈米粒子分散液於室溫靜置1週後，以目視觀察是否有粒子的沉降。未觀察到粒子的沉降。Further, the obtained silver nanoparticle dispersion was allowed to stand at room temperature for one week, and then it was visually observed whether or not particles were sedimented. No sedimentation of the particles was observed.

利用光散射式粒度分佈測量裝置(MicrotracBEL(股)製，商品名：NANOTRAC UPA150)測量分散在獲得的銀奈米粒子分散液中之銀奈米粒子的粒徑。由其測量結果可知：均勻地分散於濾液中的銀奈米粒子之平均粒徑為9nm。The particle diameter of the silver nanoparticles dispersed in the obtained silver nanoparticle dispersion was measured by a light scattering type particle size distribution measuring apparatus (manufactured by MicrotracBEL Co., Ltd., trade name: NANOTRAC UPA150). From the measurement results, it was found that the average particle diameter of the silver nanoparticles uniformly dispersed in the filtrate was 9 nm.

得到的銀奈米粒子分散液中，就以新癸酸、2-乙基己氧丙胺被覆的銀奈米粒子每100質量份(不含被覆劑僅銀的質量為100質量份)而言，有新癸酸、2-乙基己氧丙胺合計14.0質量份被覆於銀奈米粒子之表面。In the silver nanoparticle dispersion obtained, the silver nanoparticles coated with neodecanoic acid or 2-ethylhexyloxypropylamine are used in an amount of 100 parts by mass per 100 parts by mass (the mass of the silver containing no coating agent is 100 parts by mass). A total of 14.0 parts by mass of neodecanoic acid and 2-ethylhexyloxypropylamine were coated on the surface of the silver nanoparticles.

被覆於銀奈米粒子之被覆劑的量之測量方法如下所述。亦即，將銀奈米粒子已分散於甲基環己烷之分散液約0.1g稱量於玻璃瓶，用乾燥機(冷風)使溶劑成分乾燥成為粉狀。將乾燥粉約10mg以熱分析裝置(商品名：TG/DTA6200，SII NANOTECHNOLOGY(股)製)昇溫到500℃並進行測量，由重量減少率算出被覆劑量。The method of measuring the amount of the coating agent coated with the silver nanoparticles is as follows. In other words, about 0.1 g of the dispersion of the silver nanoparticle dispersed in methylcyclohexane was weighed into a glass bottle, and the solvent component was dried to a powder by a dryer (cold air). Approximately 10 mg of the dry powder was heated to 500 ° C by a thermal analyzer (trade name: TG/DTA6200, manufactured by SII NANOTECHNOLOGY), and measured, and the coating dose was calculated from the weight reduction ratio.

[實施例2] 使用實施例1所獲得的銀奈米粒子分散液，使該分散液所含有的銀的量成為70質量份的量，並於其中混合IP SOLVENT 2028(商品名，出光興產製，沸點213~262℃，密度0.789g/cm³ )30質量份。[Example 2] Using the silver nanoparticle dispersion liquid obtained in Example 1, the amount of silver contained in the dispersion was 70 parts by mass, and IP SOLVENT 2028 (product name, Idemitsu Kosan Co., Ltd.) was mixed therein. The system has a boiling point of 213 to 262 ° C and a density of 0.789 g/cm ³ ) of 30 parts by mass.

藉由在減壓下將得到的混合液中所含的甲基環己烷餾去，調製以IP SOLVENT 2028作為分散溶劑之印墨(印刷用導電性糊劑)。An ink (printing conductive paste) using IP SOLVENT 2028 as a dispersion solvent was prepared by distilling off methylcyclohexane contained in the obtained mixed liquid under reduced pressure.

製得的印墨之黏度為11mPa･s(20℃)，金屬含量為63質量%。此黏度為能以噴墨進行印刷之黏度。The obtained ink had a viscosity of 11 mPa·s (20 ° C) and a metal content of 63% by mass. This viscosity is the viscosity that can be printed by inkjet.

使用調製而得的導電性印墨，於寬25mm、長度75mm之載玻片上以噴墨印刷塗佈寬250μm、長度15mm的圖案。此塗佈膜之平均膜厚為7μm。將得到的塗佈膜在大氣中以120℃加熱處理60分鐘實施其所含之銀奈米粒子的低溫燒結。針對製得的銀奈米粒子之低溫煅燒膜測量其電阻率。煅燒後之膜厚為1.0μm，低溫煅燒膜之電阻率為3.5μΩ･cm。Using a conductive ink prepared by modulation, a pattern having a width of 250 μm and a length of 15 mm was applied by inkjet printing on a glass slide having a width of 25 mm and a length of 75 mm. The coating film had an average film thickness of 7 μm. The obtained coating film was heat-treated at 120 ° C for 60 minutes in the air to carry out low-temperature sintering of the silver nanoparticles contained therein. The resistivity of the produced low-temperature calcined film of silver nanoparticles was measured. The film thickness after calcination was 1.0 μm, and the resistivity of the low-temperature calcined film was 3.5 μΩ·cm.

減壓下之甲基環己烷的餾去係於溫度35~40℃、減壓度50hPa實施。在甲基環己烷的餾出變少的時點，將減壓度提昇至35hPa、溫度定為60℃實施約30min減壓。The distillation of methylcyclohexane under reduced pressure was carried out at a temperature of 35 to 40 ° C and a reduced pressure of 50 hPa. When the distillation of methylcyclohexane was small, the degree of pressure reduction was raised to 35 hPa, and the temperature was set to 60 ° C, and the pressure was reduced for about 30 minutes.

得到的印墨之黏度使用E型旋轉黏度計(商品名：VISCOMETER TV-25 TypeL，東機產業(股)製)並以20℃、60rpm進行測量。The viscosity of the obtained ink was measured using an E-type rotational viscometer (trade name: VISCOMETER TV-25 Type L, manufactured by Toki Sangyo Co., Ltd.) at 20 ° C and 60 rpm.

將印墨約0.8g稱量於坩堝，並以灰化爐於700℃實施30min煅燒，稱量金屬量並由其值算出金屬含量。About 0.8 g of ink was weighed into a crucible, and calcined in an ashing furnace at 700 ° C for 30 min, the amount of metal was weighed, and the metal content was calculated from the value.

[實施例3] 使用實施例1所獲得的銀奈米粒子分散液，使該分散液所含有的銀的量成為87質量份的量，並於其中混合IP SOLVENT 2835(商品名，出光興產製，沸點277~353℃，密度0.82g/cm³ )13質量份。[Example 3] Using the silver nanoparticle dispersion liquid obtained in Example 1, the amount of silver contained in the dispersion was 87 parts by mass, and IP SOLVENT 2835 (product name, Idemitsu Kosan) was mixed therein. The system has a boiling point of 277 to 353 ° C and a density of 0.82 g/cm ³ ) of 13 parts by mass.

藉由在減壓下將得到的混合液中所含的甲基環己烷餾去，調製以IP SOLVENT 2835作為分散溶劑之糊劑。The methylcyclohexane contained in the obtained mixed liquid was distilled off under reduced pressure to prepare a paste using IP SOLVENT 2835 as a dispersion solvent.

調製而成的導電性糊劑之黏度使用E型旋轉黏度計(商品名：VISCOMETER TV-25 TypeH，東機產業(股)製)於25℃、60rpm進行測量。黏度為30Pa･s(25℃)，金屬含量為79質量%。此黏度為能以凹版反轉印刷、網版印刷進行印刷之黏度。The viscosity of the prepared conductive paste was measured at 25 ° C and 60 rpm using an E-type rotational viscometer (trade name: VISCOMETER TV-25 Type H, manufactured by Toki Sangyo Co., Ltd.). The viscosity is 30 Pa·s (25 ° C), and the metal content is 79% by mass. This viscosity is the viscosity that can be printed by gravure reverse printing or screen printing.

使用調製而成的糊劑，以網版印刷於寬25mm、長度75mm之載玻片上印刷寬5mm、長度30mm的圖案。此塗佈膜之平均膜厚為20μm。將得到的塗佈膜在大氣中以120℃加熱處理60分鐘，實施其所含有的銀奈米粒子之低溫燒結。針對製得的銀奈米粒子之低溫煅燒膜測量其電阻率。煅燒後之膜厚為3.5μm，低溫煅燒膜之電阻率為6.5μΩ･cm。Using a prepared paste, a pattern having a width of 5 mm and a length of 30 mm was printed on a glass slide having a width of 25 mm and a length of 75 mm by screen printing. The coating film had an average film thickness of 20 μm. The obtained coating film was heat-treated at 120 ° C for 60 minutes in the air to carry out low-temperature sintering of the silver nanoparticles contained therein. The resistivity of the produced low-temperature calcined film of silver nanoparticles was measured. The film thickness after calcination was 3.5 μm, and the resistivity of the low-temperature calcined film was 6.5 μΩ·cm.

[實施例4] 使用實施例3所獲得的導電性糊劑，使該糊劑所含有的銀的量成為50質量份的量，並於其中混合銀粉Ag-SHA-224(商品名，同和電子製，平均粒徑0.5μm)50質量份、及IP SOLVENT 2835(沸點277~353℃，密度0.82g/cm³ ，出光興產)2.0質量份，以攪拌消泡裝置使銀粉均勻地分散，獲得導電性糊劑。[Example 4] Using the conductive paste obtained in Example 3, the amount of silver contained in the paste was 50 parts by mass, and silver powder Ag-SHA-224 (product name, same electron) was mixed therein. 50 parts by mass, an average particle diameter of 0.5 μm), and 2.0 parts by mass of IP SOLVENT 2835 (boiling point: 277 to 353 ° C, density: 0.82 g/cm ³ , Idemitsu Kosan), and uniformly disperse the silver powder by a stirring defoaming device to obtain Conductive paste.

調製而成的糊劑之黏度為50Pa･s(25℃)，金屬含量為87質量%。此黏度為能以凹版反轉印刷、網版印刷進行印刷之黏度。The prepared paste had a viscosity of 50 Pa·s (25 ° C) and a metal content of 87% by mass. This viscosity is the viscosity that can be printed by gravure reverse printing or screen printing.

使用調製而成的糊劑，與實施例3同樣地實施網版印刷及低溫煅燒。以網版印刷形成的塗佈膜之平均膜厚為25μm。煅燒後之膜厚為7μm，低溫煅燒膜之電阻率為8.5μΩ･cm。Screen printing and low-temperature baking were carried out in the same manner as in Example 3 using the prepared paste. The coating film formed by screen printing had an average film thickness of 25 μm. The film thickness after calcination was 7 μm, and the resistivity of the low-temperature calcined film was 8.5 μΩ·cm.

[實施例5] 將新癸酸(單元羧酸)之添加量由18.4質量份變更為10質量份，除此之外，與實施例1同樣地調製銀奈米粒子分散液。銀奈米粒子之產率雖降低但分散安定性良好。[Example 5] A silver nanoparticle dispersion liquid was prepared in the same manner as in Example 1 except that the amount of neodecanoic acid (unit carboxylic acid) was changed from 18.4 parts by mass to 10 parts by mass. Although the yield of silver nanoparticles is lowered, the dispersion stability is good.

[實施例6] 使用實施例5所獲得的銀奈米粒子分散液替換實施例1所獲得的銀奈米粒子分散液，除此之外，與實施例3同樣地製得印刷用導電性糊劑，並實施印刷及煅燒。導電性糊劑係均勻地製成，以120℃、60分鐘之煅燒得到7μΩ･cm(煅燒後膜厚4μm)之導電性。[Example 6] A conductive paste for printing was obtained in the same manner as in Example 3 except that the silver nanoparticle dispersion liquid obtained in Example 5 was used instead of the silver nanoparticle dispersion liquid obtained in Example 1. And carry out printing and calcination. The conductive paste was uniformly formed, and was calcined at 120 ° C for 60 minutes to obtain conductivity of 7 μΩ·cm (4 μm after calcination).

[實施例7] 將新癸酸(單元羧酸)之添加量由18.4質量份變更為25質量份，除此之外，與實施例1同樣地調製銀奈米粒子分散液。雖得到分散安定性優良的銀奈米粒子但被覆劑量有些增加。[Example 7] A silver nanoparticle dispersion liquid was prepared in the same manner as in Example 1 except that the amount of neodecanoic acid (unit carboxylic acid) was changed from 18.4 parts by mass to 25 parts by mass. Although silver nanoparticles having excellent dispersion stability were obtained, the coating dose was somewhat increased.

[實施例8] 使用實施例7所獲得的銀奈米粒子分散液替換實施例1所獲得的銀奈米粒子分散液，除此之外，與實施例3同樣地製得印刷用導電性糊劑，並實施印刷及煅燒。導電性糊劑係均勻地製成，以120℃、60分鐘之煅燒得到9.5μΩ･cm(煅燒後膜厚5μm)之導電性。[Example 8] A conductive paste for printing was obtained in the same manner as in Example 3 except that the silver nanoparticle dispersion liquid obtained in Example 7 was used instead of the silver nanoparticle dispersion liquid obtained in Example 1. And carry out printing and calcination. The conductive paste was uniformly prepared, and was fired at 120 ° C for 60 minutes to obtain conductivity of 9.5 μΩ·cm (5 μm after calcination).

[實施例9] 就單元羧酸而言，使用2-乙基己酸(碳數8)15.4質量份替換新癸酸(碳數10)18.4質量份，除此之外，與實施例1同樣地調製銀奈米粒子分散液。惟，單元羧酸之莫耳量係與實施例1相同。即使變更單元羧酸的種類仍會得到高產率且分散安定性優良的銀奈米粒子。[Example 9] The same as in Example 1, except that 15.4 parts by mass of neodecanoic acid (carbon number 10) was replaced with 15.4 parts by mass of 2-ethylhexanoic acid (carbon number 8). The silver nanoparticle dispersion is prepared. However, the molar amount of the unit carboxylic acid was the same as in Example 1. Even if the type of the unit carboxylic acid is changed, silver nanoparticles having high yield and excellent dispersion stability can be obtained.

[實施例10] 使用實施例9所獲得的銀奈米粒子分散液，使該分散液所含有的銀的量成為65質量份的量，並於其中混合NAPHTESOL 220(商品名，JX日礦日石能源製，沸點221~240℃，密度0.814g/cm³ )35質量份。除此點之外，與實施例2同樣地調製以NAPHTESOL 220作為分散溶劑之導電性印墨，並進行評價。導電性印墨係均勻地製成，以120℃、60分鐘之煅燒得到3.9μΩ･cm(煅燒後膜厚1.1μm)之導電性。[Example 10] Using the silver nanoparticle dispersion liquid obtained in Example 9, the amount of silver contained in the dispersion was 65 parts by mass, and NAPHTESOL 220 (trade name, JX Nissan Day) was mixed therein. Made of stone energy, boiling point 221 ~ 240 ° C, density 0.814g / cm ³ ) 35 parts by mass. Except for this point, a conductive ink using NAPHTESOL 220 as a dispersion solvent was prepared and evaluated in the same manner as in Example 2. The conductive ink was uniformly formed, and calcined at 120 ° C for 60 minutes to obtain conductivity of 3.9 μΩ · cm (film thickness after firing was 1.1 μm).

[實施例11] 使用實施例9所獲得的銀奈米粒子分散液替換實施例1所獲得的銀奈米粒子分散液，除此之外，與實施例3同樣地製得印刷用導電性糊劑。導電性糊劑係均勻地製成，以120℃、60分鐘之煅燒得到6.8μΩ･cm(煅燒後膜厚5μm)之導電性。[Example 11] A conductive paste for printing was obtained in the same manner as in Example 3 except that the silver nanoparticle dispersion liquid obtained in Example 9 was used instead of the silver nanoparticle dispersion liquid obtained in Example 1. Agent. The conductive paste was uniformly formed, and calcined at 120 ° C for 60 minutes to obtain conductivity of 6.8 μΩ·cm (5 μm after calcination).

[實施例12] 將2-乙基己氧丙胺(1級胺)之添加量由23.1質量份變更為15質量份，除此之外，與實施例1同樣地調製銀奈米粒子分散液。銀奈米粒子之產率雖有些降低但仍會得到分散安定性優良的粒子。[Example 12] A silver nanoparticle dispersion liquid was prepared in the same manner as in Example 1 except that the amount of the addition of 2-ethylhexyloxypropylamine (1 grade amine) was changed from 23.1 parts by mass to 15 parts by mass. Although the yield of silver nanoparticles is somewhat lowered, particles having excellent dispersion stability are obtained.

[實施例13] 使用實施例12所獲得的銀奈米粒子分散液替換實施例1所獲得的銀奈米粒子分散液，除此之外，與實施例3同樣地製得印刷用導電性糊劑。導電性糊劑係均勻地製成，以120℃、60分鐘之煅燒得到6.7μΩ･cm(煅燒後膜厚3.2μm)之導電性。[Example 13] A conductive paste for printing was obtained in the same manner as in Example 3 except that the silver nanoparticle dispersion liquid obtained in Example 12 was used instead of the silver nanoparticle dispersion liquid obtained in Example 1. Agent. The conductive paste was uniformly formed, and calcined at 120 ° C for 60 minutes to obtain conductivity of 6.7 μΩ·cm (3.2 μm after calcination).

[實施例14]銀奈米粒子分散液之調製 將1級胺由2-乙基己氧丙胺(碳數11)變更為二丁胺基丙胺(碳數11)，除此之外，與實施例1同樣地製得銀奈米粒子分散液。即使變更1級胺的種類仍會得到高產率且分散安定性優良的銀奈米粒子。[Example 14] Preparation of silver nanoparticle dispersion liquid The first-stage amine was changed from 2-ethylhexyloxypropylamine (carbon number 11) to dibutylaminopropylamine (carbon number 11), and In the same manner as in Example 1, a silver nanoparticle dispersion was obtained. Even if the type of the first-grade amine is changed, silver nanoparticles having high yield and excellent dispersion stability can be obtained.

[實施例15] 使用實施例14所獲得的銀奈米粒子分散液替換實施例1所獲得的銀奈米粒子分散液，除此之外，與實施例3同樣地製得印刷用導電性糊劑。導電性糊劑係均勻地製成，以120℃、60分鐘之煅燒得到8.2μΩ･cm(煅燒後膜厚3μm)之導電性。[Example 15] A conductive paste for printing was obtained in the same manner as in Example 3 except that the silver nanoparticle dispersion liquid obtained in Example 14 was used instead of the silver nanoparticle dispersion liquid obtained in Example 1. Agent. The conductive paste was uniformly prepared, and calcined at 120 ° C for 60 minutes to obtain conductivity of 8.2 μΩ·cm (film thickness after firing) of 3 μm.

[實施例16] 將1級胺由2-乙基己氧丙胺(碳數11)23.1質量份變更為癸胺(碳數10)19.4質量份，除此之外，與實施例1同樣地製得銀奈米粒子分散液。即使變更1級胺的種類仍會得到高產率且分散安定性優良的銀奈米粒子。[Example 16] The same procedure as in Example 1 was carried out except that the first-grade amine was changed from 23.1 parts by mass of 2-ethylhexyloxypropylamine (carbon number 11) to 19.9 parts by mass of decylamine (carbon number: 10). A silver nanoparticle dispersion is obtained. Even if the type of the first-grade amine is changed, silver nanoparticles having high yield and excellent dispersion stability can be obtained.

[實施例17] 使用實施例16所獲得的銀奈米粒子分散液，使該分散液所含有的銀的量成為65質量份的量，並於其中混合IP SOLVENT 2028(商品名，出光興產製，沸點213~262℃，密度0.789g/cm³ )35質量份。除此點之外，與實施例2同樣地調製將IP SOLVENT 2028作為分散溶劑之導電性印墨，並進行評價。 導電性印墨係均勻地製成，以120℃、60分鐘之煅燒得到4.2μΩ･cm(煅燒後膜厚1.2μm)之導電性。[Example 17] Using the silver nanoparticle dispersion liquid obtained in Example 16, the amount of silver contained in the dispersion liquid was 65 parts by mass, and IP SOLVENT 2028 (trade name, Idemitsu Kosan Co., Ltd.) was mixed therein. The system has a boiling point of 213 to 262 ° C and a density of 0.789 g/cm ³ ) of 35 parts by mass. Except for this point, a conductive ink using IP SOLVENT 2028 as a dispersion solvent was prepared and evaluated in the same manner as in Example 2. The conductive ink was uniformly formed, and calcined at 120 ° C for 60 minutes to obtain conductivity of 4.2 μΩ · cm (1.2 μm after calcination).

[實施例18] 使用實施例16所獲得的銀奈米粒子分散液替換實施例1所獲得的銀奈米粒子分散液，除此之外，與實施例3同樣地製得印刷用導電性糊劑。導電性糊劑係均勻地製成，以120℃、60分鐘之煅燒得到7μΩ･cm(煅燒後膜厚3.8μm)之導電性。[Example 18] A conductive paste for printing was obtained in the same manner as in Example 3 except that the silver nanoparticle dispersion liquid obtained in Example 16 was used instead of the silver nanoparticle dispersion liquid obtained in Example 1. Agent. The conductive paste was uniformly prepared, and was fired at 120 ° C for 60 minutes to obtain conductivity of 7 μΩ·cm (film thickness after calcination: 3.8 μm).

[實施例19] 將2級胺的種類由二異丙胺變更為二丁胺，除此之外，與實施例1同樣地調製銀奈米粒子分散液。即使變更2級胺的種類仍會得到高產率且分散安定性優良的銀奈米粒子。[Example 19] A silver nanoparticle dispersion liquid was prepared in the same manner as in Example 1 except that the type of the amine was changed from diisopropylamine to dibutylamine. Even if the type of the second-order amine is changed, silver nanoparticles having high yield and excellent dispersion stability can be obtained.

[實施例20] 使用實施例19所獲得的銀奈米粒子分散液替換實施例1所獲得的銀奈米粒子分散液，除此之外，與實施例3同樣地製得印刷用導電性糊劑。導電性糊劑係均勻地製成，以120℃、60分鐘之煅燒得到7.5μΩ･cm(煅燒後膜厚3.6μm)之導電性。[Example 20] A conductive paste for printing was obtained in the same manner as in Example 3 except that the silver nanoparticle dispersion liquid obtained in Example 19 was used instead of the silver nanoparticle dispersion liquid obtained in Example 1. Agent. The conductive paste was uniformly formed, and calcined at 120 ° C for 60 minutes to obtain conductivity of 7.5 μΩ·cm (film thickness after calcination: 3.6 μm).

[比較例1] 在本例中未摻合新癸酸，且僅使用1級胺作為胺化合物來調製銀奈米粒子分散液。[Comparative Example 1] In this example, neonic acid was not blended, and only a primary amine was used as an amine compound to prepare a silver nanoparticle dispersion.

･步驟a1 使粉末狀氧化銀(I)100質量份(0.43莫耳份)分散於甲基環己烷550質量份。在室溫(25℃)攪拌下，歷時3~5分鐘滴加甲酸41.3質量份(0.90莫耳份)於所得到的分散液中。使其成為就氧化銀(I)之Ag每1莫耳添加有甲酸1.04莫耳量。- Step a1 100 parts by mass of powdery silver oxide (I) (0.43 mol parts) was dispersed in 550 parts by mass of methylcyclohexane. 41.3 parts by mass (0.90 mole parts) of formic acid was added dropwise to the obtained dispersion over a period of 3 to 5 minutes while stirring at room temperature (25 ° C). It was made to add 1.04 moles of formic acid per 1 mole of Ag for silver oxide (I).

在烴溶劑即甲基環己烷中生成甲酸銀。由於甲酸的添加，放熱反應會進行而液溫會上昇到約45℃。若粉末狀氧化銀轉化為甲酸銀的話，其後反應液之溫度會下降。Silver formate is formed in a hydrocarbon solvent, methylcyclohexane. Due to the addition of formic acid, the exothermic reaction proceeds and the liquid temperature rises to about 45 °C. If the powdery silver oxide is converted to silver formate, the temperature of the reaction liquid thereafter decreases.

･步驟b1 在反應液之溫度下降到27℃以下之時點，於反應液中添加已將2-乙基己氧丙胺138質量份溶解於甲基環己烷92質量份而成的溶液。使其成為就初始原料之氧化銀(I)之Ag每1莫耳添加有2-乙基己氧丙胺0.86莫耳量。In the step b1, when the temperature of the reaction liquid dropped to 27 ° C or lower, a solution obtained by dissolving 138 parts by mass of 2-ethylhexyloxypropylamine in 92 parts by mass of methylcyclohexane was added to the reaction liquid. It was made that the amount of 2-ethylhexyloxypropylamine was 0.86 mole per 1 mole of Ag of silver oxide (I) as a starting material.

因胺的添加所為之酸鹼的中和反應以致液溫會上昇到約65℃。隨著液溫的上昇，經由甲酸銀之胺錯合物，會發生甲酸銀之分解性還原反應。因還原反應而析出的銀奈米粒子受到系統內之2-乙基己氧丙胺保護，藉此會抑制銀奈米粒子的肥大化。反應液的顏色從甲酸銀呈懸浮之灰色的狀態，隨著因胺添加所致甲酸銀的溶解而變化為茶色，並伴隨起泡而變化為深藍色。液溫上昇到約65℃後，繼續反應液的攪拌，在液溫下降到45℃的時點停止攪拌。The neutralization reaction of the acid and base due to the addition of the amine causes the liquid temperature to rise to about 65 °C. As the liquid temperature rises, a decomposable reduction reaction of silver formate occurs via an amine complex of silver formate. The silver nanoparticles precipitated by the reduction reaction are protected by 2-ethylhexyloxypropylamine in the system, thereby suppressing the enlargement of the silver nanoparticles. The color of the reaction liquid changed from a state in which the silver formate was suspended to a gray color, and it changed to a brown color as the silver formate was dissolved by the addition of the amine, and changed to a deep blue color with foaming. After the liquid temperature rose to about 65 ° C, the stirring of the reaction liquid was continued, and the stirring was stopped when the liquid temperature was lowered to 45 ° C.

･步驟c~e 針對得到的深藍色分散液，實施與實施例1之步驟c、d及e同樣的操作，獲得銀奈米粒子分散液。- Steps c to e The same procedure as in steps c, d and e of Example 1 was carried out on the obtained dark blue dispersion to obtain a silver nanoparticle dispersion.

針對得到的銀奈米粒子分散液實施與實施例1同樣的評價。銀之產率為98%。銀奈米粒子之平均粒徑為7nm。又銀奈米粒子分散液中，就銀奈米粒子每100質量份而言，有2-乙基己氧丙胺28.2質量份被覆於銀奈米粒子之表面。The same evaluation as in Example 1 was carried out on the obtained silver nanoparticle dispersion. The yield of silver was 98%. The average particle diameter of the silver nanoparticles is 7 nm. In the silver nanoparticle dispersion, 28.2 parts by mass of 2-ethylhexyloxypropylamine is coated on the surface of the silver nanoparticles per 100 parts by mass of the silver nanoparticles.

[比較例2] 使用比較例1所獲得的銀奈米粒子分散液替換實施例1所獲得的銀奈米粒子分散液，除此之外，與實施例2同樣地製得印刷用導電性印墨，並實施噴墨印刷及煅燒。[Comparative Example 2] A conductive print for printing was produced in the same manner as in Example 2 except that the silver nanoparticle dispersion liquid obtained in Comparative Example 1 was used instead of the silver nanoparticle dispersion liquid obtained in Example 1. Ink, and inkjet printing and calcination are carried out.

以噴墨印刷形成的塗佈膜之平均膜厚為7μm。煅燒後之膜厚為0.7μm，低溫煅燒膜之電阻率為5μΩ･cm。The coating film formed by inkjet printing had an average film thickness of 7 μm. The film thickness after calcination was 0.7 μm, and the resistivity of the low-temperature calcined film was 5 μΩ·cm.

[比較例3] 使用比較例1所獲得的銀奈米粒子分散液替換實施例1所獲得的銀奈米粒子分散液，除此之外，與實施例3同樣地製得導電性糊劑。[Comparative Example 3] A conductive paste was obtained in the same manner as in Example 3 except that the silver nanoparticle dispersion liquid obtained in Comparative Example 1 was used instead of the silver nanoparticle dispersion liquid obtained in Example 1.

調製而成的導電性糊劑係黏接性高且完全不會流動的狀態，無法進行黏度測量。導電性糊劑就印刷用而言係為不適合的狀態。使用金屬刮刀用手將導電性糊劑塗佈於玻璃上並於120℃實施煅燒，但膜破損嚴重且無法測量導電性。The prepared conductive paste has a high adhesion property and does not flow at all, and the viscosity measurement cannot be performed. The conductive paste is in an unsuitable state for printing. The conductive paste was applied to the glass by hand using a metal doctor blade and calcined at 120 ° C, but the film was severely damaged and the conductivity could not be measured.

[比較例4] 將1級胺由2-乙基己氧丙胺(碳數11)23.1質量份變更為十二胺(碳數12)22.9質量份，除此之外，與實施例1同樣地製得銀奈米粒子分散液。即使變更1級胺的種類仍會得到高產率且分散安定性優良的銀奈米粒子。[Comparative Example 4] The same procedure as in Example 1 except that the amount of the amine was changed from 23.1 parts by mass of 2-ethylhexyloxypropylamine (carbon number 11) to 22.9 parts by mass of dodecylamine (carbon number 12). A silver nanoparticle dispersion was obtained. Even if the type of the first-grade amine is changed, silver nanoparticles having high yield and excellent dispersion stability can be obtained.

[比較例5] 使用比較例4所獲得的銀奈米粒子分散液替換實施例1所獲得的銀奈米粒子分散液，除此之外，與實施例3同樣地製得導電性糊劑。導電性糊劑雖均勻地製成但以120℃、60分鐘之煅燒無法獲得導電性。在以200℃、30分鐘之煅燒獲得6μΩ･cm(煅燒後膜厚3μm)之導電性。[Comparative Example 5] A conductive paste was obtained in the same manner as in Example 3 except that the silver nanoparticle dispersion liquid obtained in Comparative Example 4 was used instead of the silver nanoparticle dispersion liquid obtained in Example 1. Although the conductive paste was uniformly formed, it was not possible to obtain conductivity by calcination at 120 ° C for 60 minutes. The electrical conductivity of 6 μΩ·cm (film thickness after firing 3 μm) was obtained by calcination at 200 ° C for 30 minutes.

[比較例6] 將1級胺由2-乙基己氧丙胺(碳數11)23.1質量份變更為2-乙基己胺(碳數8)15.9質量份，除此之外，嘗試與實施例1同樣地製作銀奈米粒子分散液。即使變更1級胺的種類，利用胺所為之甲酸銀的還原反應仍會生成銀奈米粒子，但也混有沉降的銀粒子。又，在甲醇的添加所為之奈米粒子的清洗步驟中，沉降的粒子會逐漸增加，無法獲得能再分散於甲基環己烷(步驟e)之奈米粒子。[Comparative Example 6] An attempt was made to carry out an attempt to change the first-grade amine from 23.1 parts by mass of 2-ethylhexyloxypropylamine (carbon number 11) to 15.9 parts by mass of 2-ethylhexylamine (carbon number 8). In the same manner as in Example 1, a silver nanoparticle dispersion liquid was produced. Even if the type of the amine of the first-order amine is changed, the silver nanoparticle is formed by the reduction reaction of the silver formate by the amine, but the precipitated silver particles are also mixed. Further, in the washing step of the nanoparticles in which the addition of methanol is carried out, the precipitated particles are gradually increased, and the nanoparticles which can be redispersed in methylcyclohexane (step e) cannot be obtained.

[比較例7] 不使用2-乙基己氧丙胺(1級胺)，而使用二異丙胺(2級胺)128質量份，除此之外，嘗試與實施例1同樣地製作銀奈米粒子分散液。2級胺添加後，反應液會放熱，成為靛藍色之均勻狀態後，銀粒子會肥大化並沉降。溶劑之甲基環己烷中無分散的粒子，且有灰色的銀粒子沉降。[Comparative Example 7] Silver nanoparticles were prepared in the same manner as in Example 1 except that 2-ethylhexyloxypropylamine (grade 1 amine) was used instead of 128 parts by mass of diisopropylamine (second-grade amine). Particle dispersion. After the addition of the second-grade amine, the reaction liquid will exotherm and become a uniform state of indigo, and the silver particles will be enlarged and settled. There are no dispersed particles in the methylcyclohexane solvent, and gray silver particles are precipitated.

[比較例8] 不添加單元羧酸來調製銀奈米粒子分散液。亦即，實施與比較例1之步驟a1同樣的操作，然後實施與實施例1之步驟b、c、d及e同樣的操作來調製銀奈米粒子分散液。產率雖降低，但仍會得到銀奈米粒子呈均勻地分散之銀奈米粒子分散液。但是，若在室溫放置約1天的話即會發生沉降，無法維持分散的安定性。[Comparative Example 8] A silver nanoparticle dispersion liquid was prepared without adding a unit carboxylic acid. Namely, the same operation as in the step a1 of Comparative Example 1 was carried out, and then the same operations as in the steps b, c, d and e of Example 1 were carried out to prepare a silver nanoparticle dispersion liquid. Although the yield is lowered, a silver nanoparticle dispersion in which silver nanoparticles are uniformly dispersed is obtained. However, if it is left at room temperature for about one day, sedimentation will occur and the stability of dispersion cannot be maintained.

[比較例9] 將單元羧酸由新癸酸(碳數10)18.4質量份變更為庚酸(碳數7)13.9質量份，除此之外，與實施例1同樣地調製銀奈米粒子分散液。即使變更單元羧酸的種類仍會得到高產率且分散安定的粒子，但被覆劑量變多。[Comparative Example 9] Silver nanoparticles were prepared in the same manner as in Example 1 except that the unit carboxylic acid was changed from 18.4 parts by mass of neodecanoic acid (carbon number 10) to heptanoic acid (carbon number 7) of 13.9 parts by mass. Dispersions. Even if the type of the carboxylic acid is changed, high-yield and dispersed particles are obtained, but the coating amount is increased.

[比較例10] 使用比較例9所獲得的銀奈米粒子分散液替換實施例1所獲得的銀奈米粒子分散液，除此之外，與實施例2同樣地製得導電性糊劑並實施噴墨印刷及煅燒。導電性印墨雖均勻地製成但以120℃、60分鐘之煅燒無法得到導電性。在以180℃、60分鐘之煅燒獲得8μΩ･cm(煅燒後膜厚0.8μm)之導電性。據認為原因是因羧酸的鏈長較短，對銀之配位力增強。[Comparative Example 10] A conductive paste was obtained in the same manner as in Example 2 except that the silver nanoparticle dispersion liquid obtained in Comparative Example 9 was used instead of the silver nanoparticle dispersion liquid obtained in Example 1. Ink jet printing and calcination were carried out. Although the conductive ink was uniformly formed, it was not able to obtain conductivity by calcination at 120 ° C for 60 minutes. The electrical conductivity of 8 μΩ·cm (the film thickness after calcination was 0.8 μm) was obtained by calcination at 180 ° C for 60 minutes. It is believed that the reason is that the chain length of the carboxylic acid is shorter and the coordination power to silver is enhanced.

於表1表示實施例中的主要成分之使用量(質量份)及評價結果。於表2表示比較例中的主要成分之使用量(質量份)及評價結果。Table 1 shows the amounts (parts by mass) of the main components used in the examples and the evaluation results. Table 2 shows the amounts of the main components (parts by mass) and the evaluation results in the comparative examples.

[表1] *1：被覆劑量係表示相對於銀100質量份之質量份； *2：導電性係表示以120℃、60分鐘之煅燒後的煅燒膜之電阻率，但此煅燒膜為絕緣性時記載為「不導電」，並顯示以另外表示之煅燒條件得到的煅燒膜之電阻率。[Table 1] *1: the coating dose means a mass part by mass of 100 parts by mass of silver; *2: Conductivity means the electrical resistivity of the calcined film after calcination at 120 ° C for 60 minutes, but when the calcined film is insulative, it is described as "Non-conducting" and showing the resistivity of the calcined film obtained by the calcination conditions otherwise indicated.

[表2] *1：被覆劑量係表示相對於銀100質量份之質量份； *2：導電性係表示以120℃、60分鐘之煅燒後的煅燒膜之電阻率，但此煅燒膜為絕緣性時記載為「不導電」，並顯示以另外表示之煅燒條件得到的煅燒膜之電阻率。[Table 2] *1: the coating dose means a mass part by mass of 100 parts by mass of silver; *2: Conductivity means the electrical resistivity of the calcined film after calcination at 120 ° C for 60 minutes, but when the calcined film is insulative, it is described as "Non-conducting" and showing the resistivity of the calcined film obtained by the calcination conditions otherwise indicated.

無no

Claims (8)

一種銀奈米粒子分散液之調製方法，係調製在表面具有由被覆劑分子構成的被覆層之平均粒徑5~20nm的銀奈米粒子之分散液的方法，其特徵為： 包含以下步驟： a) 在烴溶劑中，使甲酸作用於粉末狀氧化銀(I)，使粉末狀氧化銀(I)轉化為甲酸銀(I)；及 b) 在該烴溶劑中，於碳數8~11之單元羧酸的存在下，利用胺化合物所為之還原反應將甲酸銀(I)中所含的銀陽離子還原為銀原子，藉此形成表面被胺化合物及單元羧酸被覆而成之平均粒徑5~20nm之銀奈米粒子； 使用碳數9~11之1級胺與2級胺兩者作為該胺化合物。A method for preparing a silver nanoparticle dispersion liquid, which is a method for preparing a dispersion of silver nanoparticles having an average particle diameter of 5 to 20 nm of a coating layer composed of a coating agent molecule on the surface, comprising the steps of: a) in the hydrocarbon solvent, formic acid is applied to the powdered silver oxide (I) to convert the powdery silver (I) oxide to silver formate (I); and b) in the hydrocarbon solvent, at a carbon number of 8 to 11 In the presence of the unit carboxylic acid, the silver cation contained in the silver formate (I) is reduced to a silver atom by a reduction reaction of the amine compound, thereby forming an average particle diameter of the surface coated with the amine compound and the unit carboxylic acid. Silver nanoparticles of 5 to 20 nm; both of the amines having a carbon number of 9 to 11 and the amines of the second amine are used as the amine compound. 如申請專利範圍第1項之銀奈米粒子分散液之調製方法，其中， 該烴溶劑係具有65℃~155℃的沸點之碳數6~9的直鏈或環狀烷； 在步驟a中，就該粉末狀氧化銀(I)每100質量份使用該烴溶劑400質量份~700質量份。The method for preparing a silver nanoparticle dispersion according to the first aspect of the invention, wherein the hydrocarbon solvent is a linear or cyclic alkane having a carbon number of from 6 to 9 having a boiling point of from 65 ° C to 155 ° C; The powdery silver oxide (I) is used in an amount of from 400 parts by mass to 700 parts by mass per 100 parts by mass of the hydrocarbon solvent. 如申請專利範圍第1或2項之銀奈米粒子分散液之調製方法，其中， 該1級胺之分子量為120~200； 該1級胺具有對該烴溶劑有親和性之脂肪族烴鏈。The method for preparing a silver nanoparticle dispersion according to claim 1 or 2, wherein the primary amine has a molecular weight of 120 to 200; and the tertiary amine has an aliphatic hydrocarbon chain having affinity for the hydrocarbon solvent. . 如申請專利範圍第1或2項之銀奈米粒子分散液之調製方法，其中， 該2級胺之分子量為100~150； 該2級胺具有對該烴溶劑有親和性之脂肪族烴鏈。The method for preparing a silver nanoparticle dispersion according to claim 1 or 2, wherein the secondary amine has a molecular weight of 100 to 150; and the secondary amine has an aliphatic hydrocarbon chain having affinity for the hydrocarbon solvent. . 如申請專利範圍第1或2項之銀奈米粒子分散液之調製方法，其中， 在步驟b中，就甲酸銀(I)所含的銀陽離子每1莫耳量， 使用該單元羧酸0.05莫耳量~0.3莫耳量； 使用該1級胺0.05莫耳量~0.3莫耳量；及 使用該2級胺，以使1級胺與2級胺之總莫耳量為1.1莫耳量~1.5莫耳量之範圍。The method for preparing a silver nanoparticle dispersion according to claim 1 or 2, wherein in the step b, the silver cation contained in the silver formate (I) is used per mole of the carboxylic acid 0.05. Mole amount ~ 0.3 moles; use the first amine 0.05 moles ~ 0.3 moles; and use the second amine, so that the total amount of amines of the first and second amines is 1.1 moles ~1.5 molar range. 如申請專利範圍第1或2項之銀奈米粒子分散液之調製方法，更包含下述步驟c~e： c) 在減壓下使該烴溶劑氣化而從得自於步驟b之反應液去除，藉此回收含有該銀奈米粒子之殘渣； d) 以醇清洗該殘渣；及 e) 使在步驟d清洗後的殘渣分散於和該烴溶劑相同或不同的烴溶劑中而獲得銀奈米粒子分散液。The method for preparing a silver nanoparticle dispersion according to claim 1 or 2 further comprises the following steps c~e: c) vaporizing the hydrocarbon solvent under reduced pressure from the reaction obtained from step b The liquid is removed, thereby recovering the residue containing the silver nanoparticles; d) washing the residue with alcohol; and e) dispersing the residue after the step d washing in a hydrocarbon solvent which is the same as or different from the hydrocarbon solvent to obtain silver Nanoparticle dispersion. 一種印刷用導電性糊劑之調製方法，係使用利用如申請專利範圍第1至6項中任一項之銀奈米粒子分散液之調製方法調製而成的銀奈米粒子分散液來調製印刷用導電性糊劑。A method for preparing a conductive paste for printing by using a silver nanoparticle dispersion prepared by a method for preparing a silver nanoparticle dispersion according to any one of claims 1 to 6 to prepare a printing Use a conductive paste. 一種印刷用導電性糊劑，含有在表面具有由被覆劑分子構成的被覆層之平均粒徑5~20nm的銀奈米粒子； 該被覆層含有碳數8~11之單元羧酸及碳數9~11之1級胺。A conductive paste for printing comprising silver nanoparticle having an average particle diameter of 5 to 20 nm of a coating layer composed of a coating agent molecule on a surface thereof; the coating layer containing a unit carboxylic acid having a carbon number of 8 to 11 and a carbon number of 9 ~11 of the first grade amine.