JP2010180471A - Flaky silver powder and method for producing the same, and conductive paste - Google Patents
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Abstract
Description
本発明は、導電性ペーストの配合物等に用いられるフレーク状銀粉及びその製造方法、並びに導電性ペーストに関する。 The present invention relates to a flaky silver powder used for a conductive paste composition, a method for producing the same, and a conductive paste.
従来から、電子部品などの電極や回路を形成するために、銀粉を有機成分中に分散させた導電性ペーストが使用されている。導電性ペーストの中でも、樹脂硬化型の導電性ペースト（例えば、特許文献１参照）においては、樹脂の体積収縮により銀粉同士が接触して導通が取られる。よって、樹脂硬化型の導電性ペーストに配合される銀粉としては、接触面積が大きいフレーク状銀粉が使用されている（例えば、特許文献２参照）。 Conventionally, a conductive paste in which silver powder is dispersed in an organic component has been used to form electrodes and circuits such as electronic components. Among the conductive pastes, in a resin curable conductive paste (see, for example, Patent Document 1), silver powders come into contact with each other due to the volume shrinkage of the resin, and conduction is obtained. Therefore, flaky silver powder having a large contact area is used as the silver powder blended in the resin curable conductive paste (see, for example, Patent Document 2).
このようなフレーク状銀粉は、一般に、球状又は不定形状の銀粉をフレーク化することにより得ることができる。球状又は不定形状の銀粉をフレーク化する方法としては、例えば、アトライタを用いた湿式粉砕法や、ボールミル（例えば、特許文献３参照）、振動ミル等を用いた乾式粉砕法など、様々な方法が報告されている。また、前記球状又は不定形状の銀粉の製造方法としても、湿式還元法（例えば、特許文献４参照）や、アトマイズ法による製造方法など、様々な方法が報告されている。 Such flaky silver powder can generally be obtained by flaking spherical or irregularly shaped silver powder. As a method for flaking spherical or irregularly shaped silver powder, there are various methods such as a wet pulverization method using an attritor, a dry pulverization method using a ball mill (for example, see Patent Document 3), a vibration mill, and the like. It has been reported. Moreover, various methods, such as a wet reduction method (for example, refer patent document 4) and the manufacturing method by the atomizing method, are reported also as a manufacturing method of the said spherical or irregular-shaped silver powder.
しかしながら、このような従来の製造方法により製造されたフレーク状銀粉を導電性ペースト用配合物に用いると、得られるペーストの粘度が高くなる場合があり、ペーストの混練性が低下し、ペースト中に銀粉が十分に分散できないという問題があった。ペーストの粘度が高くなると、ペーストの印刷性が悪くなり、ペーストを塗布した際に、塗布面に凹凸やかすれが発生し易くなる。また、ペーストの粘度が高くなると、ペーストの混練に時間がかかり、ペースト製造工程の生産性が悪化し、製造コストが増加するという問題もある。
また、従来の製造方法により製造されたフレーク状銀粉は、導電性ペーストにして、導電膜を形成した場合、導電膜の抵抗は、球状等の形状を持つ銀粉を使用した場合より低くなるものの、その効果は、十分とはいえず、導電膜の抵抗を更に低減することが求められていた。
However, when the flaky silver powder produced by such a conventional production method is used in a compound for a conductive paste, the viscosity of the resulting paste may be increased, and the kneadability of the paste may be reduced. There was a problem that silver powder could not be sufficiently dispersed. When the viscosity of the paste is increased, the printability of the paste is deteriorated, and when the paste is applied, unevenness and fading are easily generated on the application surface. Moreover, when the viscosity of a paste becomes high, it takes time to knead the paste, and there is a problem that the productivity of the paste manufacturing process deteriorates and the manufacturing cost increases.
In addition, when the flaky silver powder produced by the conventional production method is made into a conductive paste and a conductive film is formed, the resistance of the conductive film is lower than when silver powder having a spherical shape or the like is used, The effect is not sufficient, and it has been demanded to further reduce the resistance of the conductive film.
本発明は、従来における前記諸問題を解決し、以下の目的を達成することを課題とする。即ち、本発明は、従来の製造方法により製造されたフレーク状銀粉よりも、フレーク状銀粉を配合した導電性ペーストの粘度を低下されることができ、且つ、フレーク状銀粉を配合した導電性ペーストを用いて形成した導電膜の抵抗を低下させることができるフレーク状銀粉及びその製造方法、並びに導電性ペーストを提供することを目的とする。 An object of the present invention is to solve the above-described problems and achieve the following objects. That is, according to the present invention, the viscosity of the conductive paste containing the flaky silver powder can be reduced as compared with the flaky silver powder produced by the conventional production method, and the conductive paste containing the flaky silver powder. It aims at providing the flaky silver powder which can reduce the resistance of the electrically conductive film formed using this, its manufacturing method, and an electrically conductive paste.
本発明者らは、前記課題を解決するために鋭意検討を重ねた結果、銀粉をフレーク化処理した後に、フレーク化処理後の銀粉に対し、前記銀粉の粒子同士を機械的に衝突させる表面平滑化処理を施すことにより、得られるフレーク状銀粉が、従来の製法により得られたフレーク状銀粉よりも、フレーク状銀粉を配合した導電性ペーストの粘度を低下させることができ、且つ、フレーク状銀粉を配合した導電性ペーストを用いて形成した導電膜の抵抗を低下させることができることを見出し、本発明を完成するに至った。 As a result of intensive studies to solve the above problems, the present inventors have made surface smoothing by mechanically colliding the particles of the silver powder with the silver powder after the flaking process, after the silver powder has been subjected to a flake process. The flaky silver powder obtained can be reduced in viscosity of the conductive paste blended with the flaky silver powder than the flaky silver powder obtained by the conventional production method, and the flaky silver powder. The present inventors have found that the resistance of a conductive film formed using a conductive paste blended with can be reduced, and have completed the present invention.
本発明は、本発明者らによる前記知見に基づくものであり、前記課題を解決するための手段としては、以下の通りである。即ち、
＜１＞ フレーク化処理後の銀粉に対して、前記銀粉の粒子同士を機械的に衝突させる表面平滑化処理を施すことを特徴とするフレーク状銀粉の製造方法である。
＜２＞ 表面平滑化処理が、フレーク状銀粉を収納可能な容器と、前記容器中に設置され、周速１５ｍ／ｓ以上で回転可能な羽根とを有する高速攪拌機を用いて施される前記＜１＞に記載のフレーク状銀粉の製造方法である。
＜３＞ 高速攪拌機の羽根の周速が３０ｍ／ｓ〜７０ｍ／ｓである前記＜２＞に記載のフレーク状銀粉の製造方法である。
＜４＞ 表面平滑化処理の処理時間が、１分間〜６０分間である前記＜１＞から＜３＞のいずれかに記載のフレーク状銀粉の製造方法である。
＜５＞ 前記＜１＞から＜４＞のいずれかに記載のフレーク状銀粉の製造方法によって製造されたことを特徴とするフレーク状銀粉である。
＜６＞ 前記＜５＞に記載のフレーク状銀粉を用いて作製されたことを特徴とする導電性ペーストである。
The present invention is based on the above findings by the present inventors, and means for solving the above problems are as follows. That is,
<1> A method for producing flaky silver powder, characterized by subjecting the silver powder after the flaking treatment to a surface smoothing treatment that mechanically collides the particles of the silver powder.
<2> The surface smoothing treatment is performed using a high-speed stirrer having a container capable of storing flaky silver powder and a blade installed in the container and rotatable at a peripheral speed of 15 m / s or more. 1> The method for producing flaky silver powder according to 1>.
<3> The method for producing flaky silver powder according to <2>, wherein the peripheral speed of the blades of the high-speed stirrer is 30 m / s to 70 m / s.
<4> The method for producing flaky silver powder according to any one of <1> to <3>, wherein the treatment time for the surface smoothing treatment is 1 minute to 60 minutes.
<5> A flaky silver powder produced by the method for producing a flaky silver powder according to any one of <1> to <4>.
<6> A conductive paste produced using the flaky silver powder according to <5>.
本発明によれば、従来における前記諸問題を解決し、前記目的を達成することができ、従来の製造方法により製造されたフレーク状銀粉よりも、フレーク状銀粉を配合した導電性ペーストの粘度を低下されることができ、且つ、フレーク状銀粉を配合した導電性ペーストを用いて形成した導電膜の抵抗を低下させることができるフレーク状銀粉及びその製造方法、並びに導電性ペーストを提供することができる。
本発明のフレーク状銀粉をペーストに配合することにより、従来よりもペーストの粘度を低下させることができ、ペーストの印刷性や混練性を向上させることが可能である。また、本発明のフレーク状銀粉をペーストに配合することにより、そのペーストを用いて形成した導電膜の抵抗を、従来の製造方法により製造されたフレーク状銀粉を配合したペーストと比較して低下させることができる点でも、有利である。
According to the present invention, the conventional problems can be solved and the object can be achieved, and the viscosity of the conductive paste blended with the flaky silver powder is more than the flaky silver powder produced by the conventional production method. It is possible to provide a flaky silver powder that can be lowered and that can reduce the resistance of a conductive film formed using a conductive paste containing flaky silver powder, a method for producing the same, and a conductive paste. it can.
By blending the flaky silver powder of the present invention into the paste, the viscosity of the paste can be reduced as compared with the conventional case, and the printability and kneadability of the paste can be improved. In addition, by adding the flaky silver powder of the present invention to the paste, the resistance of the conductive film formed using the paste is reduced as compared with the paste containing the flaky silver powder manufactured by the conventional manufacturing method. This is also advantageous.
（フレーク状銀粉の製造方法）
本発明のフレーク状銀粉の製造方法は、フレーク化処理後の銀粉に対して、前記銀粉の粒子同士を機械的に衝突させる表面平滑化処理を施す工程を少なくとも含み、更に必要に応じて、適宜その他の工程を含む。
(Method for producing flaky silver powder)
The method for producing flaky silver powder of the present invention includes at least a step of subjecting the silver powder after flaking to a surface smoothing treatment to mechanically collide the particles of the silver powder, and if necessary, as appropriate. Including other processes.
＜フレーク化処理後の銀粉＞
前記フレーク化処理後の銀粉とは、銀粉にフレーク化処理を施すことにより得られるフレーク状銀粉である。
前記フレーク化処理を施す対象となる銀粉としては、特に制限はなく、目的に応じて適宜選択することができるが、中でも、球状又は不定形状の銀粉が好ましい。ここで、球状とは、ＳＥＭで銀粉を観察した場合、粒子形状が球形または略球形であり、粒子１００個の球状度（球状度：ＳＥＭ写真で粒子を観察した時の、（最も長径部の径）／（最も短径部の径））が１．５以下である銀粉をいい、また、不定形状とは、ＳＥＭで観察した場合、粒子形状が、前記球状以外であり、円柱状、角柱状等の特定の粒子形状の特徴を有しない銀粉のことをいう。前記球状又は不定形状銀粉としては、特に制限はなく、目的に応じて適宜選択することができ、例えば、湿式還元法（例えば、特開平０７−７６７１０号公報参照）や、アトマイズ法など、公知の手法で得られた球状又は不定形状銀粉を、適宜利用することができる。
また、前記銀粉にフレーク化処理を施す方法としては、特に制限はなく、目的に応じて適宜選択することができ、例えば、アトライタを用いた湿式粉砕法や、ボールミル（例えば、特開２００３−５５７０１号公報参照）、振動ミル等を用いた乾式粉砕法など、公知の手法を適宜利用することができる。
<Silver powder after flaking>
The silver powder after the flaking process is a flaky silver powder obtained by subjecting the silver powder to a flaking process.
There is no restriction | limiting in particular as silver powder used as the object which performs the said flaking process, Although it can select suitably according to the objective, Among these, spherical or indefinite-shaped silver powder is preferable. Here, when the silver powder is observed with an SEM, the spherical shape means that the particle shape is spherical or substantially spherical, and the sphericity of 100 particles (sphericity: when the particles are observed with an SEM photograph (the longest diameter part) (Diameter) / (diameter of the shortest diameter portion)) is 1.5 or less, and the indefinite shape is a particle shape other than the above-mentioned sphere when observed by SEM, a cylindrical shape, a corner It refers to silver powder that does not have a specific particle shape characteristic such as a columnar shape. The spherical or irregularly shaped silver powder is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a known reduction method such as a wet reduction method (see, for example, JP-A-07-76710) or an atomizing method is known. Spherical or amorphous silver powder obtained by the technique can be used as appropriate.
The method for flaking the silver powder is not particularly limited and may be appropriately selected depending on the purpose. For example, a wet pulverization method using an attritor, a ball mill (for example, JP-A-2003-55701) can be selected. Well-known techniques such as dry pulverization using a vibration mill or the like can be used as appropriate.
また、前記銀粉に、分散剤を混合した上で、前記フレーク化処理を施すことにより、得られるフレーク化処理後の銀粉の分散性を向上させることも可能である。
前記分散剤としては、特に制限はなく、目的に応じて適宜選択することができ、例えば、脂肪酸、脂肪酸塩、界面活性剤、有機金属、キレート形成剤、保護コロイド等が挙げられ、これらの中でも、脂肪酸が好ましい。前記脂肪酸としては、例えば、プロピオン酸、カプリル酸、ラウリン酸、ミリスチン酸、パルミチン酸、ステアリン酸、ベヘン酸、アクリル酸、オレイン酸、リノール酸、アラキドン酸など又はそれらの混合物が挙げられる。
Moreover, it is also possible to improve the dispersibility of the obtained silver powder after the flaking process by mixing the silver powder with a dispersant and then performing the flaking process.
The dispersant is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include fatty acids, fatty acid salts, surfactants, organic metals, chelating agents, protective colloids, and the like. Fatty acids are preferred. Examples of the fatty acid include propionic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, acrylic acid, oleic acid, linoleic acid, arachidonic acid, and mixtures thereof.
＜表面平滑化処理＞
本発明のフレーク状銀粉の製造方法では、前記のようにして得られたフレーク化処理後の銀粉に対して、前記銀粉の粒子同士を機械的に衝突させる表面平滑化処理を施すことを特徴とする。前記表面平滑化処理は、フレーク化処理後の銀粉を高速（流動型）攪拌機に入れて高速攪拌機内に設置された羽根（ブレード）を高速で回転させることにより行うことができ、銀粉をフレーク化処理した後に、フレーク化処理後の銀粉に対し、前記銀粉の粒子同士を機械的に衝突させる表面平滑化処理を施すことにより、得られるフレーク状銀粉が、従来の製法により得られたフレーク状銀粉よりも、フレーク状銀粉を配合した導電性ペーストの粘度を低下させることができ、且つ、フレーク状銀粉を配合した導電性ペーストを用いて形成した導電膜の抵抗を低下させることができる。
<Surface smoothing treatment>
In the method for producing flaky silver powder of the present invention, the silver powder after the flaking treatment obtained as described above is subjected to a surface smoothing treatment for mechanically colliding the particles of the silver powder. To do. The surface smoothing treatment can be performed by putting the silver powder after flaking treatment into a high-speed (fluid type) stirrer and rotating a blade (blade) installed in the high-speed stirrer at high speed to make the silver powder flakes. After the treatment, the flaky silver powder obtained by subjecting the silver powder after the flaking treatment to a surface smoothing treatment that mechanically collides the particles of the silver powder is obtained by a conventional method. As a result, the viscosity of the conductive paste blended with the flaky silver powder can be reduced, and the resistance of the conductive film formed using the conductive paste blended with the flaky silver powder can be decreased.
前記表面平滑化処理に用いる高速攪拌機としては、フレーク状銀粉を収納可能な容器と、前記容器中に設置され、羽根回転数（ｒｐｍ）×羽根径（ｍ）×π÷６０で求められる周速（ｍ／ｓ）が１５ｍ／ｓ以上で回転可能な羽根（ブレード）とを有する装置である限り、特に制限はなく、目的に応じて適宜選択することができ、例えば、ヘンシェルミキサー等の筒型高速攪拌機、マイクロスピードミキサ、ハイスピードミキサ、などが挙げられる。フレーク状銀粉は、前記高速攪拌機の羽根が高速回転することにより、前記高速攪拌機内で、流動化され、銀粉の粒子同士が高頻度で機械的に強く衝突して、表面が平滑化される。 As a high-speed stirrer used for the surface smoothing treatment, a container capable of storing flaky silver powder and a peripheral speed which is installed in the container and obtained by blade rotation speed (rpm) × blade diameter (m) × π ÷ 60 As long as the device has a blade (blade) that can rotate at (m / s) of 15 m / s or more, there is no particular limitation, and it can be appropriately selected according to the purpose. For example, a cylindrical shape such as a Henschel mixer A high speed stirrer, a micro speed mixer, a high speed mixer, etc. are mentioned. The flaky silver powder is fluidized in the high-speed stirrer when the blades of the high-speed stirrer rotate at a high speed, and the particles of the silver powder mechanically and strongly collide with each other at a high frequency to smooth the surface.
前記表面平滑化処理を行う際の、高速攪拌機の羽根の周速としては、１５ｍ／ｓ〜９０ｍ／ｓが好ましく、３０ｍ／ｓ〜７０ｍ／ｓがより好ましい。前記回転数が、１５ｍ／ｓ未満であると、表面平滑化の効果が十分得られないことがあり、９０ｍ／ｓを超えると、通常の装置では実現が難しいことがある。また、前記回転数は、必要な処理時間を短縮するためには、３０ｍ／ｓ以上がより好ましく、装置のコスト等を考慮すると、７０ｍ／ｓ以下がより好ましい。 The peripheral speed of the blades of the high-speed stirrer when performing the surface smoothing treatment is preferably 15 m / s to 90 m / s, and more preferably 30 m / s to 70 m / s. When the rotational speed is less than 15 m / s, the effect of smoothing the surface may not be sufficiently obtained, and when it exceeds 90 m / s, it may be difficult to realize with a normal apparatus. The rotational speed is more preferably 30 m / s or more in order to shorten the necessary processing time, and more preferably 70 m / s or less in consideration of the cost of the apparatus.
前記表面平滑化処理を行う際の、表面平滑化処理時間としては、１分間〜６０分間が好ましく、５分間〜６０分間がより好ましい。前記表面平滑化処理時間が、１分間未満であると、表面平滑化の効果が得られないことがあり、６０分間超えて処理しても効果に差はなく、生産性の観点から６０分間以下が好ましい。前記表面平滑化処理時間が５分間以上であると、表面平滑化の効果をより安定して得られるので、より好ましい。 The surface smoothing treatment time for performing the surface smoothing treatment is preferably 1 minute to 60 minutes, and more preferably 5 minutes to 60 minutes. When the surface smoothing treatment time is less than 1 minute, the effect of surface smoothing may not be obtained. Even if the treatment is performed for more than 60 minutes, there is no difference in effect, and from the viewpoint of productivity, 60 minutes or less Is preferred. It is more preferable that the surface smoothing treatment time is 5 minutes or longer, since the effect of surface smoothing can be obtained more stably.
以上のような表面平滑化処理を経て得られたフレーク状銀粉は、表面平滑化処理を経ずに得られるフレーク状銀粉よりも、フレーク状銀粉を配合した導電性ペーストの粘度を低くすることができ、フレーク状銀粉を配合した導電性ペーストを用いて形成した導電膜の抵抗を低くすることができるという特性を有する。得られたフレーク状銀粉の詳細は、後述する本発明のフレーク状銀粉の項目に記載する通りであるが、このフレーク状銀粉は、例えば、導電性ペースト用の配合物等に、好適に利用可能である。 The flaky silver powder obtained through the surface smoothing treatment as described above may lower the viscosity of the conductive paste containing the flaky silver powder than the flaky silver powder obtained without the surface smoothing treatment. And the resistance of the conductive film formed using the conductive paste containing flaky silver powder can be lowered. The details of the obtained flaky silver powder are as described in the item of the flaky silver powder of the present invention described later. This flaky silver powder can be suitably used, for example, for a composition for conductive paste. It is.
（フレーク状銀粉）
本発明のフレーク状銀粉は、本発明のフレーク状銀粉の製造方法により製造されるフレーク状銀粉である。
なお、本明細書中で、「フレーク状銀粉」とは、アスペクト比が３以上である銀粉をいう。ここで、前記アスペクト比は、（平均長径Ｌ／平均厚さＴ）により求めることができる。「平均長径Ｌ」と「平均厚さＴ」は、走査型電子顕微鏡で測定した粒子１００個の平均長径と平均厚さを示す。
前記フレーク状銀粉のアスペクト比としては、３以上である限り、特に制限はなく、目的に応じて適宜選択することができるが、５〜１０が好ましい。
(Flake silver powder)
The flaky silver powder of the present invention is a flaky silver powder produced by the method for producing a flaky silver powder of the present invention.
In the present specification, “flaky silver powder” refers to silver powder having an aspect ratio of 3 or more. Here, the aspect ratio can be obtained by (average major axis L / average thickness T). “Average major axis L” and “average thickness T” indicate the average major axis and average thickness of 100 particles measured with a scanning electron microscope.
There is no restriction | limiting in particular as long as it is 3 or more as an aspect-ratio of the said flaky silver powder, Although it can select suitably according to the objective, 5-10 are preferable.
前記フレーク状銀粉は、表面平滑化処理を行わないフレーク状銀粉と比較して、フレーク状銀粉を配合した導電性ペーストの５ｒｐｍにおける粘度が、１５％以上小さいことが好ましく、フレーク状銀粉を配合した導電性ペーストを塗布及び加熱することにより形成した塗膜の比抵抗は２５％以上低いことが好ましい。
前記フレーク状銀粉の粒径（Ｄ５０）としては、特に制限はなく、目的に応じて適宜選択することができるが、１μｍ〜１０μｍが好ましい。
前記フレーク状銀粉の比表面積としては、特に制限はなく、目的に応じて適宜選択することができるが、０．２ｍ２／ｇ〜２．０ｍ２／ｇが好ましい。
前記フレーク状銀粉のタップ密度としては、特に制限はなく、目的に応じて適宜選択することができるが、３ｇ／ｃｍ３〜６ｇ／ｃｍ３が好ましい。
The flaky silver powder preferably has a viscosity at 5 rpm of the conductive paste containing the flaky silver powder of 15% or more smaller than that of the flaky silver powder not subjected to the surface smoothing treatment. The specific resistance of the coating film formed by applying and heating the conductive paste is preferably 25% or more low.
There is no restriction | limiting in particular as a particle size (D50) of the said flaky silver powder, Although it can select suitably according to the objective, 1 micrometer-10 micrometers are preferable.
The specific surface area of the flaky silver powder is not particularly limited and may be appropriately selected depending on the intended purpose, preferably 0.2m 2 /g~2.0m 2 / g.
The tap density of the flaky silver powder is not particularly limited and may be appropriately selected depending on the intended purpose, 3g / cm 3 ~6g / cm 3 are preferred.
（導電性ペースト）
本発明の導電性ペースト（本明細書中、単に「ペースト」と称する場合がある）は、本発明のフレーク状銀粉を用いて作製される導電性ペーストであり、例えば、樹脂硬化型ペースト、などが挙げられる。
(Conductive paste)
The conductive paste of the present invention (sometimes referred to simply as “paste” in the present specification) is a conductive paste produced using the flaky silver powder of the present invention, such as a resin curable paste. Is mentioned.
前記導電性ペーストの作製方法としては、特に制限はなく、従来公知の手法の中から、目的に応じて適宜選択することができ、例えば、前記フレーク状銀粉を、任意の樹脂と混合することにより作製することができる。
前記樹脂としては、特に制限はなく、目的に応じて適宜選択することができ、例えば、エポキシ樹脂、アクリル樹脂、ポリエステル樹脂、ポリイミド樹脂、ポリウレタン樹脂、フェノキシ樹脂、シリコーン樹脂など又はそれらの混合物が挙げられる。
前記導電性ペーストにおける、前記フレーク状銀粉の含有量としても、特に制限はなく、目的に応じて適宜選択することができる。
There is no restriction | limiting in particular as a preparation method of the said electrically conductive paste, According to the objective from the conventionally well-known methods, it can select suitably, For example, by mixing the said flaky silver powder with arbitrary resin Can be produced.
There is no restriction | limiting in particular as said resin, According to the objective, it can select suitably, For example, an epoxy resin, an acrylic resin, a polyester resin, a polyimide resin, a polyurethane resin, a phenoxy resin, a silicone resin etc. or those mixtures are mentioned. It is done.
There is no restriction | limiting in particular also as content of the said flaky silver powder in the said electrically conductive paste, According to the objective, it can select suitably.
本発明の導電性ペーストは、高速攪拌機を用いた表面平滑化処理を経て製造された本発明のフレーク状銀粉を含有してなることから、従来のフレーク状銀粉を含有する導電性ペーストに比較して、粘度が低く、また、フレーク状銀粉を配合した導電性ペーストを用いて形成した導電膜の抵抗が低い。そのため、本発明の導電性ペーストは、混練性、印刷性、導電性等に優れるものであり、種々の電子部品の電極や回路を形成するための導電性ペーストの配合物に、好適に利用可能である。 Since the conductive paste of the present invention contains the flaky silver powder of the present invention produced through a surface smoothing process using a high-speed stirrer, it is compared with the conductive paste containing the conventional flaky silver powder. In addition, the viscosity of the conductive film is low, and the resistance of the conductive film formed using a conductive paste containing flaky silver powder is low. Therefore, the conductive paste of the present invention is excellent in kneadability, printability, conductivity, etc., and can be suitably used for a composition of conductive paste for forming electrodes and circuits of various electronic parts. It is.
以下、本発明の実施例について説明するが、本発明は、これらの実施例に何ら限定されるものではない。 Examples of the present invention will be described below, but the present invention is not limited to these examples.
（実施例１）
以下のようにして、フレーク化処理後の銀粉に、高速攪拌機を用いた表面平滑化処理を施すことにより、本発明のフレーク状銀粉を製造した。また、得られたフレーク状銀粉を用い、本発明のペーストを作製した。また、前記ペーストを塗布及び加熱処理することにより導電膜を形成した。得られたフレーク状銀粉、ペースト、及び導電膜のそれぞれにつき、各特性を以下のようにして確認した。
Example 1
The flaky silver powder of the present invention was produced by subjecting the silver powder after the flaking treatment to a surface smoothing treatment using a high-speed stirrer as follows. Moreover, the paste of this invention was produced using the obtained flaky silver powder. Moreover, the electrically conductive film was formed by apply | coating and heat-processing the said paste. Each characteristic was confirmed as follows about each of the obtained flaky silver powder, paste, and electrically conductive film.
＜フレーク状銀粉の製造＞
銀イオン水溶液としての２.７％の硝酸銀水溶液３７５ｋｇに、２５％アンモニア水溶液１９ｋｇを加えて、銀アンミン錯体水溶液を生成した。生成した銀アンミン錯体水溶液に還元剤として３７％ホルマリン水溶液２５ｋｇを加えた。また、還元剤を加えた直後に、分散剤としてステアリン酸１０ｇを加え、銀粉を含むスラリーを生成した。得られたスラリーをろ過、水洗した後、乾燥熱処理して、銀粉を１０ｋｇ得た。
上記により得た銀粉を三井鉱山（株）製のヘンシェルミキサーＦＭ７５型（羽根：Ａｏ型（一般タイプ））を用いて、羽根回転数１，０００ｒｐｍ、処理時間１０分間の条件にて解砕を行い、ＢＥＴ１点法により測定した比表面積は０．１７ｍ２／ｇ、レーザー回折式粒度分布測定法により測定したＤ５０は７．２μｍであった。また、前記銀粉の形状を走査型電子顕微鏡で確認したところ不定形状の銀粉であることが確認された。
得られた銀粉に、分散剤としての脂肪酸（パルミチン酸）を０．１５質量％加えてよく混ぜ、ＳＵＳボール（直径１．６ｍｍ）とともに振動ボールミルに入れて、振動数１，２００ｖｐｍ、振幅６ｍｍ、処理時間６時間の条件でフレーク化処理を実施した。
<Manufacture of flaky silver powder>
A silver ammine complex aqueous solution was formed by adding 19 kg of a 25% aqueous ammonia solution to 375 kg of a 2.7% silver nitrate aqueous solution as a silver ion aqueous solution. To the resulting silver ammine complex aqueous solution, 25 kg of 37% formalin aqueous solution was added as a reducing agent. Immediately after adding the reducing agent, 10 g of stearic acid was added as a dispersant to produce a slurry containing silver powder. The obtained slurry was filtered, washed with water, and then dried and heat-treated to obtain 10 kg of silver powder.
The silver powder obtained above was crushed using a Henschel mixer FM75 type (blade: Ao type (general type)) manufactured by Mitsui Mining Co., Ltd. under the conditions of a blade rotation speed of 1,000 rpm and a treatment time of 10 minutes. The specific surface area measured by the BET 1-point method was 0.17 m 2 / g, and the D 50 measured by the laser diffraction particle size distribution measurement method was 7.2 μm. Moreover, when the shape of the said silver powder was confirmed with the scanning electron microscope, it was confirmed that it was an indefinite shape silver powder.
To the obtained silver powder, 0.15% by mass of a fatty acid (palmitic acid) as a dispersant was added and mixed well, and placed in a vibration ball mill with a SUS ball (diameter 1.6 mm), with a vibration frequency of 1,200 vpm, an amplitude of 6 mm, The flaking process was implemented on the conditions for the processing time of 6 hours.
＜フレーク状銀粉の表面平滑化処理＞
得られたフレーク化処理後のフレーク状銀粉８ｋｇに対して、三井鉱山（株）製のヘンシェルミキサーＦＭ２０型（羽根：Ｓｏ型（強攪拌タイプ））を用いて、羽根径０．２９ｍ、羽根回転数２，３００ｒｐｍ、周速３５ｍ／ｓ、処理時間２０分間の条件にて、表面平滑化処理を行った。
表面平滑化処理条件、表面平滑化処理後のフレーク状銀粉の平均粒径Ｄ５０、表面平滑化処理後のフレーク状銀粉のアスペクト比、表面平滑化処理後のフレーク状銀粉の比表面積、及び表面平滑化処理後のフレーク状銀粉のタップ密度を表１に示す。なお、平均粒径Ｄ５０、比表面積、タップ密度の各測定方法は以下に示す通りである。
<Surface smoothening treatment of flaky silver powder>
Using Henshell mixer FM20 type (blade: So type (strong stirring type)) manufactured by Mitsui Mining Co., Ltd. Surface smoothing was performed under the conditions of several 2,300 rpm, a peripheral speed of 35 m / s, and a processing time of 20 minutes.
Surface smoothing treatment conditions, surface smoothing treatment flaky silver powder average particle diameter D 50 of the post, the aspect ratio of the flaky silver powder after surface smoothing treatment, the specific surface area of the flaky silver powder after surface smoothing treatment, and the surface Table 1 shows the tap density of the flaky silver powder after the smoothing treatment. The average particle diameter D 50, the specific surface area, the method of measuring tap density are as shown below.
−平均粒径Ｄ５０の測定方法−
平均粒径Ｄ５０は、レーザー回折散乱式粒度分布測定装置（日機装（株）製、ＭＩＣＲＯＴＯＲＡＣ ＨＲＡ）を用いて、銀粉０．３ｇをイソプロパノール３０ｍＬに加え、超音波分散処理を５分間行って試料を準備し、全反射モードで測定を行った。
- The method for measuring the mean particle size D 50 -
The average particle diameter D 50 is obtained by adding 0.3 g of silver powder to 30 mL of isopropanol using a laser diffraction scattering type particle size distribution measuring apparatus (manufactured by Nikkiso Co., Ltd., MICROTORAC HRA), and subjecting the sample to ultrasonic dispersion treatment for 5 minutes. Prepared and measured in total reflection mode.
−比表面積の測定方法−
比表面積は、ＭＯＮＯＳＯＲＢ装置（湯浅アイオニクス（株）製）で、Ｈｅ７０％、Ｎ２３０％のキャリアガスを用い、銀粉３ｇをセルに入れて脱気を６０℃で１０分間行った後、ＢＥＴ１点法により測定を行った。
-Measurement method of specific surface area-
The specific surface area was determined by using a MONOSORB apparatus (manufactured by Yuasa Ionics Co., Ltd.), using 70% He and 30% N 2 carrier gas, putting 3 g of silver powder into the cell, degassing at 60 ° C. for 10 minutes, and then BET1 Measurements were made by the point method.
−タップ密度の測定方法−
タップ密度は、タップ密度測定装置（柴山化学機器製作所製、カサ比重測定装置ＳＳ−ＤＡ−２）を使用し、銀粉試料３０ｇを計量して、容器（２０ｍＬ試験管）に入れ、落差２０ｍｍで１，０００回タッピングした後、容器の目盛から銀粉の体積を読み取り、タップ密度＝試料重量（３０ｇ）／タッピング後の試料体積、から算出した。
-Tap density measurement method-
The tap density was measured by using a tap density measuring device (manufactured by Shibayama Chemical Equipment Co., Ltd., Casa Specific Gravity Measuring Device SS-DA-2), weighing 30 g of a silver powder sample, and putting it in a container (20 mL test tube). After tapping 1,000 times, the volume of the silver powder was read from the scale of the container and calculated from tap density = sample weight (30 g) / sample volume after tapping.
＜ペーストの作製＞
また、（１）表面平滑化処理後のフレーク状銀粉、（２）エポキシ樹脂、（３）希釈剤及び（４）硬化剤を含む組成物を下記組成比で混練することによりペーストを作製した。
（１）表面平滑化処理後のフレーク状銀粉 ８８質量部
（２）エポキシ樹脂（旭電化工業（株）製、ＥＰ−４９０１Ｅ） ８．１質量部（３）希釈剤（ジャパンエポキシレジン株式会社製、カージェラＥ） ３．５質量部（４）硬化剤（三フッ化ホウ素モノエチルアミン） ０．４質量部
前記組成物を混合し、３本ロール（オットハーマン社製、ＥＸＡＫＴ８０Ｓ）を用いて、ロールギャップを１００μｍから２０μｍまで通過させて混練処理を行うことによりペーストを得た。得られたペーストは完全に混練されていた。
得られたペーストの粘度を、Ｅ型粘度計（ＢＲＯＯＫＦＩＥＬＤ社製、ＤＶ−III＋）を用い、コーンスピンドルＣＰ−５２、ペースト温度２５℃、回転数５ｒｐｍの条件で測定した。結果を表１に示す。実施例１のペーストは、表面平滑化処理を行わずに得られたフレーク状銀粉を用いて作製された後述する比較例１のペーストに比べ、低い粘度を示した。
<Preparation of paste>
Moreover, the paste was produced by knead | mixing the composition containing (1) flaky silver powder after a surface smoothing process, (2) epoxy resin, (3) diluent, and (4) hardening | curing agent with the following composition ratio.
(1) Flaky silver powder after surface smoothing treatment 88 parts by mass (2) Epoxy resin (Asahi Denka Kogyo Co., Ltd., EP-4901E) 8.1 parts by mass (3) Diluent (manufactured by Japan Epoxy Resin Co., Ltd.) , Cargela E) 3.5 parts by mass (4) Curing agent (boron trifluoride monoethylamine) 0.4 parts by mass The above composition was mixed, and a roll was used using three rolls (EXAKT80S manufactured by Otto Herman). A paste was obtained by passing through the gap from 100 μm to 20 μm and kneading. The obtained paste was completely kneaded.
The viscosity of the obtained paste was measured using an E-type viscometer (BROOKFIELD, DV-III +) under conditions of a cone spindle CP-52, a paste temperature of 25 ° C., and a rotation speed of 5 rpm. The results are shown in Table 1. The paste of Example 1 showed a low viscosity as compared with the paste of Comparative Example 1 described later, which was prepared using the flaky silver powder obtained without performing the surface smoothing treatment.
＜導電膜の形成＞
スライドガラス上にメンディングテープを幅１０ｍｍ間隔で貼り、そこに得られたペーストをガラス棒で摺切り印刷した後、メンディングテープを剥がすことにより、膜厚０．０５ｍｍ、幅１０ｍｍのペーストの膜を形成した。得られた膜を大気循環式乾燥機を用い、２００℃、３０分間の条件で加熱処理し、導電膜を形成した。
得られた導電膜は表面粗さ計（株式会社小坂研究所製、ＳＥ−３０Ｄ）を用いて、スライドガラス上で膜を印刷していない部分と導電膜の部分の段差を測定することにより導電膜の膜厚を測定した。導電膜の抵抗は、デジタルマルチメーター（ＡＤＶＡＮＴＥＳＴ製、Ｒ６５５１）を用いて、導電膜の長さ(間隔）が６０ｍｍの位置の抵抗値を測定した。導電膜のサイズ（膜厚、幅、長さ）より、導電膜の体積を求め、この体積と測定した抵抗値から、比抵抗（体積抵抗率）を求めた。膜厚及び比抵抗の結果を表１に示す。実施例１の導電膜は、表面平滑化処理を行わずに得られたフレーク状銀粉を用いて作製された後述する比較例１の導電膜に比べ、低い比抵抗を示した。
<Formation of conductive film>
A mending tape is pasted on a slide glass at intervals of 10 mm in width, and the paste obtained is cut and printed with a glass rod, and then the mending tape is peeled off to remove a film having a thickness of 0.05 mm and a width of 10 mm. Formed. The obtained film was heat-treated at 200 ° C. for 30 minutes using an air circulation dryer to form a conductive film.
The obtained conductive film was made conductive by measuring the level difference between the portion where the film was not printed on the slide glass and the portion of the conductive film using a surface roughness meter (SE-30D manufactured by Kosaka Laboratory Ltd.). The film thickness was measured. The resistance of the conductive film was measured using a digital multimeter (manufactured by ADVANTEST, R6551) at the position where the length (interval) of the conductive film was 60 mm. The volume of the conductive film was determined from the size (film thickness, width, length) of the conductive film, and the specific resistance (volume resistivity) was determined from this volume and the measured resistance value. Table 1 shows the results of film thickness and specific resistance. The conductive film of Example 1 exhibited a lower specific resistance than the conductive film of Comparative Example 1 described later, which was prepared using flaky silver powder obtained without performing the surface smoothing treatment.
（実施例２）
＜フレーク状銀粉の製造＞
銀イオン水溶液としての５．８％の硝酸銀水溶液１７６ｋｇに、３０％苛性ソーダ水溶液２５ｋｇを加えて、その後に還元剤として３７％ホルマリン水溶液７ｋｇを加えた。また、還元剤を加えた直後に、分散剤としてオレイン酸１０ｇを加え、銀粉を含むスラリーを生成した。得られたスラリーをろ過、水洗した後、乾燥熱処理して、銀粉を１０ｋｇ得た。
上記により得た銀粉は、実施例１と同様の条件で解砕を行い、ＢＥＴ１点法により測定した比表面積は１．１ｍ２／ｇ、レーザー回折式粒度分布測定法により測定したＤ５０は、６．０μｍであった。また、前記銀粉の形状を走査型電子顕微鏡で確認したところ不定形状の銀粉であることが確認された。
得られた銀粉に、分散剤としての脂肪酸（オレイン酸）を０．４０質量％加えてよく混ぜ、ＳＵＳボール（直径１．６ｍｍ）とともに振動ボールミルに入れて、振動数１，４５０ｖｐｍ、振幅８ｍｍ、処理時間３時間の条件でフレーク化処理を実施した。
(Example 2)
<Manufacture of flaky silver powder>
To 176 kg of a 5.8% silver nitrate aqueous solution as a silver ion aqueous solution, 25 kg of 30% sodium hydroxide aqueous solution was added, and then 7 kg of 37% formalin aqueous solution was added as a reducing agent. Moreover, immediately after adding a reducing agent, 10 g of oleic acid was added as a dispersing agent, and the slurry containing silver powder was produced | generated. The obtained slurry was filtered, washed with water, and then dried and heat-treated to obtain 10 kg of silver powder.
The silver powder obtained above was crushed under the same conditions as in Example 1, the specific surface area measured by the BET 1-point method was 1.1 m 2 / g, and D 50 measured by the laser diffraction particle size distribution measurement method was: It was 6.0 μm. Moreover, when the shape of the said silver powder was confirmed with the scanning electron microscope, it was confirmed that it was an indefinite shape silver powder.
To the obtained silver powder, 0.40% by mass of a fatty acid (oleic acid) as a dispersant was added and mixed well, and placed in a vibrating ball mill together with a SUS ball (diameter 1.6 mm), with a frequency of 1,450 vpm, an amplitude of 8 mm, The flaking process was performed under the condition of a treatment time of 3 hours.
＜フレーク状銀粉の表面平滑化処理＞
得られたフレーク化処理後のフレーク状銀粉１９ｋｇに対して、三井鉱山（株）製のヘンシェルミキサーＦＭ７５型（羽根：Ｓｏ型（強攪拌タイプ））を用いて、羽根径０．４４ｍ、羽根回転数２，２００ｒｐｍ、周速５１ｍ／ｓ、処理時間８分間の条件にて、表面平滑化処理を行った。得られた結果を表１に示す。得られたフレーク状銀粉を用いて実施例１と同様に作製した実施例２のペーストは、表面平滑化処理を行わずに得られたフレーク状銀粉を用いて作製された後述する比較例２のペーストに比べ、低い粘度を示した。また、得られたペーストを用いて実施例１と同様に作製した実施例２の導電膜は、表面平滑化処理を行わずに得られたフレーク状銀粉を用いて作製された後述する比較例２の導電膜に比べ、低い比抵抗を示した。
<Surface smoothening treatment of flaky silver powder>
For the obtained flaky silver powder 19 kg after flaking treatment, using a Henschel mixer FM75 type (blade: So type (strong stirring type)) manufactured by Mitsui Mining Co., Ltd., blade diameter 0.44 m, blade rotation Surface smoothing was performed under the conditions of several 2,200 rpm, peripheral speed 51 m / s, and processing time 8 minutes. The obtained results are shown in Table 1. The paste of Example 2 produced using the obtained flaky silver powder in the same manner as in Example 1 was produced using the flaky silver powder obtained without performing the surface smoothing treatment. The viscosity was lower than that of the paste. Moreover, the conductive film of Example 2 produced similarly to Example 1 using the obtained paste was produced using the flaky silver powder obtained without performing the surface smoothing treatment. Comparative Example 2 described later Compared to the conductive film, the specific resistance was low.
（比較例１）
フレーク化処理後のフレーク状銀粉に対して、表面平滑化処理を行わなかったこと以外は、実施例１と同様の条件で試験を行った。得られた結果を表１に示す。比較例１のペーストは、表面平滑化処理を行って得られたフレーク状銀粉を用いて作製された実施例１のペーストに比べ、高い粘度を示した。また、比較例１の導電膜は、表面平滑化処理を行って得られたフレーク状銀粉を用いて作製された実施例１の導電膜に比べ、高い比抵抗を示した。
(Comparative Example 1)
The test was performed under the same conditions as in Example 1 except that the surface smoothing treatment was not performed on the flaky silver powder after the flaking treatment. The obtained results are shown in Table 1. The paste of Comparative Example 1 showed higher viscosity than the paste of Example 1 produced using the flaky silver powder obtained by performing the surface smoothing treatment. Moreover, the electrically conductive film of the comparative example 1 showed high specific resistance compared with the electrically conductive film of Example 1 produced using the flaky silver powder obtained by performing the surface smoothing process.
（比較例２）
フレーク化処理後のフレーク状銀粉に対して、表面平滑化処理を行わなかったこと以外は、実施例２と同様の条件で試験を行った。得られた結果を表１に示す。比較例２のペーストは、表面平滑化処理を行って得られたフレーク状銀粉を用いて作製された実施例２のペーストに比べ、高い粘度を示した。また、比較例２の導電膜は、表面平滑化処理を行って得られたフレーク状銀粉を用いて作製された実施例２の導電膜に比べ、高い比抵抗を示した。
(Comparative Example 2)
The test was performed under the same conditions as in Example 2 except that the surface smoothing treatment was not performed on the flaky silver powder after the flaking treatment. The obtained results are shown in Table 1. The paste of Comparative Example 2 showed a higher viscosity than the paste of Example 2 produced using flaky silver powder obtained by performing a surface smoothing treatment. Moreover, the electrically conductive film of the comparative example 2 showed high specific resistance compared with the electrically conductive film of Example 2 produced using the flaky silver powder obtained by performing the surface smoothing process.
（比較例３）
銀イオン水溶液としての１．３％の硝酸銀水溶液８１３ｋｇに、２５％アンモニア水溶液３８ｋｇを加えて、銀アンミン錯体水溶液を生成した。生成した銀アンミン錯体水溶液に還元剤としてホルマリン３７％水溶液４４ｋｇを加えた。また、還元剤を加えた直後に、分散剤としてステアリン酸１３ｇを加え、銀粉を含むスラリーを生成した。得られたスラリーをろ過、水洗した後、乾燥熱処理して、銀粉を１０ｋｇ得た。また、走査型電子顕微鏡で形状を確認したところ球状の銀粉であることが確認された。
上記により得た銀粉は、フレーク化処理及び表面平滑化処理を行わなかったこと以外は、実施例１と同様の条件で試験を行った（ペースト材料に用いる銀粉はフレーク状銀粉でなく、球状銀粉である）。得られた結果を表１に示す。得られた球状銀粉を用いて実施例１と同様に作製された比較例３のペーストは、表面平滑化処理を行って得られたフレーク状銀粉を用いて作製された実施例１及び２のペーストに比べ、やや低い粘度を示したが、得られたペーストを用いて実施例１と同様に作製された比較例３の導電膜は、表面平滑化処理を行って得られたフレーク状銀粉を用いて作製された実施例１及び２の導電膜に比べ、比抵抗は約１．５倍以上の値となり、導電性の点で大きく劣っていた。
(Comparative Example 3)
A silver ammine complex aqueous solution was produced by adding 38 kg of a 25% ammonia aqueous solution to 813 kg of a 1.3% silver nitrate aqueous solution as a silver ion aqueous solution. As a reducing agent, 44 kg of a formalin 37% aqueous solution was added to the resulting silver ammine complex aqueous solution. Immediately after adding the reducing agent, 13 g of stearic acid was added as a dispersant to produce a slurry containing silver powder. The obtained slurry was filtered, washed with water, and then dried and heat-treated to obtain 10 kg of silver powder. Moreover, when the shape was confirmed with a scanning electron microscope, it was confirmed to be spherical silver powder.
The silver powder obtained above was tested under the same conditions as in Example 1 except that the flaking process and the surface smoothing process were not performed (the silver powder used for the paste material was not a flaky silver powder but a spherical silver powder. Is). The obtained results are shown in Table 1. The paste of Comparative Example 3 produced in the same manner as Example 1 using the obtained spherical silver powder was the paste of Examples 1 and 2 produced using the flaky silver powder obtained by performing the surface smoothing treatment. The conductive film of Comparative Example 3 produced in the same manner as in Example 1 using the obtained paste uses flaky silver powder obtained by subjecting the surface to a smoothing treatment. Compared to the conductive films of Examples 1 and 2 produced in this way, the specific resistance was about 1.5 times or more, which was greatly inferior in terms of conductivity.
本発明のフレーク状銀粉は、従来の製法により製造されたフレーク状銀粉と比較して、フレーク状銀粉を配合したペーストの粘度を低下することができ、また、本発明のフレーク状銀粉を用いて形成した導電膜の導電性を大幅に向上することができる。そのため、本発明のフレーク状銀粉を用いて作製される導電性ペーストは、混練性、印刷性、導電性等に優れるものであり、種々の電子部品の電極や回路を形成するための導電性ペーストの配合物に、好適に利用可能である。 The flaky silver powder of the present invention can reduce the viscosity of the paste containing the flaky silver powder as compared with the flaky silver powder produced by the conventional production method, and the flaky silver powder of the present invention is used. The conductivity of the formed conductive film can be greatly improved. Therefore, the conductive paste produced using the flaky silver powder of the present invention is excellent in kneadability, printability, conductivity, etc., and is a conductive paste for forming electrodes and circuits of various electronic components. It can be suitably used for the following formulations.
Claims (6)
A conductive paste produced using the flaky silver powder according to claim 5.
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| WO2012176831A1 (en) * | 2011-06-21 | 2012-12-27 | 住友金属鉱山株式会社 | Silver dust and manufacturing method thereof |
| WO2013187608A1 (en) * | 2012-06-12 | 2013-12-19 | 주식회사 동진쎄미켐 | Conductive paste composition |
| US10000670B2 (en) | 2012-07-30 | 2018-06-19 | Henkel IP & Holding GmbH | Silver sintering compositions with fluxing or reducing agents for metal adhesion |
| JP2014196527A (en) * | 2013-03-29 | 2014-10-16 | トクセン工業株式会社 | Fine flaky particles |
| US11745294B2 (en) | 2015-05-08 | 2023-09-05 | Henkel Ag & Co., Kgaa | Sinterable films and pastes and methods for use thereof |
| JP2018035286A (en) * | 2016-09-01 | 2018-03-08 | パナソニックＩｐマネジメント株式会社 | Conductive resin composition and electronic circuit member using the same |
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