JP2020183486A - Metallic ink and printing object - Google Patents
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- JP2020183486A JP2020183486A JP2019088563A JP2019088563A JP2020183486A JP 2020183486 A JP2020183486 A JP 2020183486A JP 2019088563 A JP2019088563 A JP 2019088563A JP 2019088563 A JP2019088563 A JP 2019088563A JP 2020183486 A JP2020183486 A JP 2020183486A
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- 238000007639 printing Methods 0.000 title abstract description 35
- FOIXSVOLVBLSDH-UHFFFAOYSA-N Silver ion Chemical compound [Ag+] FOIXSVOLVBLSDH-UHFFFAOYSA-N 0.000 claims abstract description 76
- 229920000036 polyvinylpyrrolidone Polymers 0.000 claims abstract description 25
- 239000001267 polyvinylpyrrolidone Substances 0.000 claims abstract description 25
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 claims abstract description 25
- 239000002270 dispersing agent Substances 0.000 claims abstract description 20
- 239000002612 dispersion medium Substances 0.000 claims abstract description 19
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 claims description 14
- DNIAPMSPPWPWGF-UHFFFAOYSA-N Propylene glycol Chemical compound CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 claims description 9
- 235000011187 glycerol Nutrition 0.000 claims description 7
- 239000002202 Polyethylene glycol Substances 0.000 claims 1
- 229920001223 polyethylene glycol Polymers 0.000 claims 1
- 239000002932 luster Substances 0.000 abstract description 22
- XNGYKPINNDWGGF-UHFFFAOYSA-L silver oxalate Chemical compound [Ag+].[Ag+].[O-]C(=O)C([O-])=O XNGYKPINNDWGGF-UHFFFAOYSA-L 0.000 abstract description 11
- 238000000197 pyrolysis Methods 0.000 abstract 1
- 239000000976 ink Substances 0.000 description 64
- 238000000034 method Methods 0.000 description 18
- 239000006185 dispersion Substances 0.000 description 14
- 239000002245 particle Substances 0.000 description 14
- -1 silver ions Chemical class 0.000 description 14
- 229910052709 silver Inorganic materials 0.000 description 12
- 239000004332 silver Substances 0.000 description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 11
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 10
- 238000005259 measurement Methods 0.000 description 9
- 239000007788 liquid Substances 0.000 description 8
- 239000000758 substrate Substances 0.000 description 7
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 6
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 6
- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 6
- 238000000862 absorption spectrum Methods 0.000 description 6
- 238000012360 testing method Methods 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- 238000013461 design Methods 0.000 description 4
- 238000005227 gel permeation chromatography Methods 0.000 description 4
- 239000002082 metal nanoparticle Substances 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- 239000002105 nanoparticle Substances 0.000 description 4
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 150000001412 amines Chemical class 0.000 description 3
- 239000003638 chemical reducing agent Substances 0.000 description 3
- 230000006378 damage Effects 0.000 description 3
- 238000007641 inkjet printing Methods 0.000 description 3
- 238000001000 micrograph Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 229920000642 polymer Polymers 0.000 description 3
- 230000002265 prevention Effects 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 230000001133 acceleration Effects 0.000 description 2
- 239000002518 antifoaming agent Substances 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 238000005119 centrifugation Methods 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 230000001186 cumulative effect Effects 0.000 description 2
- 239000012153 distilled water Substances 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910000510 noble metal Inorganic materials 0.000 description 2
- 239000003921 oil Substances 0.000 description 2
- 239000000123 paper Substances 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 229940068886 polyethylene glycol 300 Drugs 0.000 description 2
- 229920000139 polyethylene terephthalate Polymers 0.000 description 2
- 239000005020 polyethylene terephthalate Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 229910001961 silver nitrate Inorganic materials 0.000 description 2
- 238000001542 size-exclusion chromatography Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- 238000005979 thermal decomposition reaction Methods 0.000 description 2
- 238000000870 ultraviolet spectroscopy Methods 0.000 description 2
- 229920002799 BoPET Polymers 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 229910021607 Silver chloride Inorganic materials 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 150000005215 alkyl ethers Chemical class 0.000 description 1
- 125000003277 amino group Chemical group 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000003125 aqueous solvent Substances 0.000 description 1
- 238000011088 calibration curve Methods 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- USIUVYZYUHIAEV-UHFFFAOYSA-N diphenyl ether Chemical class C=1C=CC=CC=1OC1=CC=CC=C1 USIUVYZYUHIAEV-UHFFFAOYSA-N 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000002296 dynamic light scattering Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000005286 illumination Methods 0.000 description 1
- 239000012263 liquid product Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- GEVPUGOOGXGPIO-UHFFFAOYSA-N oxalic acid;dihydrate Chemical compound O.O.OC(=O)C(O)=O GEVPUGOOGXGPIO-UHFFFAOYSA-N 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 229920006316 polyvinylpyrrolidine Polymers 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000003223 protective agent Substances 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 229940100890 silver compound Drugs 0.000 description 1
- 150000003379 silver compounds Chemical class 0.000 description 1
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 description 1
- GGCZERPQGJTIQP-UHFFFAOYSA-N sodium;9,10-dioxoanthracene-2-sulfonic acid Chemical compound [Na+].C1=CC=C2C(=O)C3=CC(S(=O)(=O)O)=CC=C3C(=O)C2=C1 GGCZERPQGJTIQP-UHFFFAOYSA-N 0.000 description 1
- 238000004528 spin coating Methods 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 108700024661 strong silver Proteins 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 1
- 229920002554 vinyl polymer Polymers 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
Abstract
Description
本発明は、メタリックインク及びそれを用いた印刷部を備える被印刷物に関する。 The present invention relates to a metallic ink and a printed matter provided with a printing unit using the metallic ink.
近年、印刷部の意匠性の観点から、金属光沢を呈するインクのニーズが高まっている。しかし、そのようなインクは、導電性の金属材料を用いることが多く、通電による電気回路のショートや電波障害等の心配から電子機器への使用は限られる。
一方で、粒径がナノメートルレベルまで微細化された金属ナノ粒子を用いたインクは、金属光沢性の意匠を呈するインクとして優れた適性を有していることが見出されている。これは、金属ナノ粒子を含有する分散液を塗布すると、分散媒の揮発に伴い、金属ナノ粒子が均一に配列し金属光沢を呈するためである。特に、金属ナノ粒子の中でも銀等の貴金属は耐食性に優れるため、銀ナノ粒子などの貴金属を用いたインクは、応用範囲が広く金属光沢性があるインクとして有用である。
In recent years, there has been an increasing need for inks having a metallic luster from the viewpoint of the design of the printing unit. However, such inks often use conductive metal materials, and their use in electronic devices is limited due to concerns about short circuits of electric circuits and radio interference caused by energization.
On the other hand, it has been found that an ink using metal nanoparticles whose particle size has been refined to the nanometer level has excellent suitability as an ink exhibiting a metallic luster design. This is because when a dispersion liquid containing metal nanoparticles is applied, the metal nanoparticles are uniformly arranged and have a metallic luster as the dispersion medium volatilizes. In particular, among metal nanoparticles, noble metals such as silver have excellent corrosion resistance, so inks using noble metals such as silver nanoparticles have a wide range of applications and are useful as inks having metallic luster.
このような銀ナノ粒子は、更に、適切な保護剤で表面を覆うことにより、低粘度の分散媒中でも沈降することなく分散性を維持する。このため、銀ナノ粒子を使用することで、低粘度のインクが用いられるインクジェット法等に適したインクを作製可能である。
ここで、銀ナノ粒子を製造する方法としては、一般には硝酸銀や塩化銀等の銀塩を溶解させた水溶液等を用いて、存在する銀イオンを何らかの還元剤により還元して所望の形態の金属塩として析出させることが通常であった（特許文献１〜特許文献３）。
By further covering the surface of such silver nanoparticles with an appropriate protective agent, the silver nanoparticles maintain their dispersibility without settling even in a low-viscosity dispersion medium. Therefore, by using silver nanoparticles, it is possible to produce an ink suitable for an inkjet method or the like in which a low-viscosity ink is used.
Here, as a method for producing silver nanoparticles, generally, an aqueous solution in which a silver salt such as silver nitrate or silver chloride is dissolved is used to reduce existing silver ions with some reducing agent to form a metal having a desired form. It was usually precipitated as a salt (Patent Documents 1 to 3).
また、シュウ酸銀とアミンを混合して熱分解することにより、シュウ酸銀アミン錯体を経て銀ナノ粒子を製造する方法等も知られている（特許文献４、特許文献５）。この手法は、銀イオンを還元するための還元剤を混合する必要がなく、単純な手法で銀ナノ粒子を製造することが可能である。更に、この手法では、アミン錯体の分解の際、アミン分子のアミノ基が銀粒子表面に配位することから、分散剤を添加しなくてもある種の分散媒に分散可能な銀ナノ粒子が得られる。
また、シュウ酸銀を熱分解させる際に、粒子の表面に配位する分子としてポリビニルピロリドンを用いて銀ナノ粒子を製造する方法もある（非特許文献１）。この手法で合成した銀ナノ粒子にはプレート状のものも含まれ、インク化した際に強い金属光沢が期待される。
Further, there are also known methods for producing silver nanoparticles via a silver oxalate amine complex by mixing silver oxalate and amine and thermally decomposing them (Patent Documents 4 and 5). This method does not require mixing a reducing agent for reducing silver ions, and silver nanoparticles can be produced by a simple method. Furthermore, in this method, since the amino group of the amine molecule is coordinated on the surface of the silver particle when the amine complex is decomposed, silver nanoparticles that can be dispersed in a certain dispersion medium without adding a dispersant can be obtained. can get.
There is also a method of producing silver nanoparticles using polyvinylpyrrolidone as a molecule coordinated on the surface of the particles when the silver oxalate is thermally decomposed (Non-Patent Document 1). The silver nanoparticles synthesized by this method include plate-shaped ones, and are expected to have a strong metallic luster when inked.
本発明はこのような事情に鑑みてなされたものであって、シュウ酸銀を熱分解して簡便に得られた銀ナノ粒子を用い、印刷部が金属光沢を示すと共に導電性が低くなるメタリックインク、及びそれを用いた被印刷物を提供することを目的とする。 The present invention has been made in view of such circumstances, and uses silver nanoparticles easily obtained by thermally decomposing silver oxalate, and the printed matter exhibits metallic luster and low conductivity. An object of the present invention is to provide an ink and a printed matter using the ink.
課題を解決するために、本発明の一態様に係るメタリックインクは、ポリビニルピロリドンで表面が保護された銀ナノ粒子と、分散剤と、分散媒と、を含むインクであり、上記インクの表面抵抗率が１０５Ω／□以上であることを要旨とする。 In order to solve the problem, the metallic ink according to one aspect of the present invention is an ink containing silver nanoparticles whose surface is protected by polyvinylpyrrolidone, a dispersant, and a dispersion medium, and the surface resistivity of the ink. rate is summarized in that at 10 5 Ω / □ or more.
本発明の一態様によれば、金属光沢を示すと共に導電性が低い印刷部を作製可能なメタリックインクを提供することができる。本発明の一態様のインクによれば、印刷部が金属光沢を示すことから意匠性が高いうえ、導電性が低いため、電波を透過する必要のある部材への印刷や、内部回路の破壊防止に繋がることが期待される。 According to one aspect of the present invention, it is possible to provide a metallic ink capable of producing a printed portion having a metallic luster and low conductivity. According to the ink of one aspect of the present invention, since the printed portion exhibits metallic luster, the design is high and the conductivity is low, so that printing on a member that needs to transmit radio waves and prevention of destruction of the internal circuit are prevented. It is expected that it will lead to.
（銀ナノ粒子を用いたメタリックインク）
以下、本発明の実施形態（以下、本実施形態）について説明する。本発明は以下の実施形態に限定されるものではない。
本実施形態に係るメタリックインク（以下、単にインクとも称する）は、ポリビニルピロリドンで表面が保護された銀ナノ粒子（以下、単に銀ナノ粒子とも称する）と、分散剤と、分散媒とを有する。
本実施形態に係るインクによって印刷された印刷部は、銀ナノ粒子同士が融着していないことが好ましい。銀ナノ粒子同士が融着していない場合、印刷部の導電性は低くなる。
(Metallic ink using silver nanoparticles)
Hereinafter, embodiments of the present invention (hereinafter, the present embodiment) will be described. The present invention is not limited to the following embodiments.
The metallic ink according to the present embodiment (hereinafter, also simply referred to as ink) has silver nanoparticles whose surface is protected by polyvinylpyrrolidone (hereinafter, also simply referred to as silver nanoparticles), a dispersant, and a dispersion medium.
It is preferable that the silver nanoparticles are not fused to each other in the printed portion printed by the ink according to the present embodiment. When the silver nanoparticles are not fused to each other, the conductivity of the printed portion becomes low.
上記印刷部の表面抵抗率は、例えば、１０５Ω／□（以下、単にΩとも称する）以上であることが好ましい。表面抵抗率が、１０５Ω以上１０９Ω以下では静電気拡散性、１０９Ω以上１０１４Ω以下で帯電防止性を示す。更に、電波透過性に必要な表面抵抗率は１０３Ω以上であるため、１０５Ω以上の表面抵抗を有する印刷部は電波透過性も示す。上記印刷部の表面抵抗率は高いほど好ましいため、上限は特にない。
本実施形態に係るインクに用いられる銀ナノ粒子を構成する銀の原料としては、加熱分解により容易に金属を生成し、かつ、銀以外の不純物を生じにくい観点から、シュウ酸銀が好ましい。シュウ酸銀は、銀含有率が高いとともに、加熱によりシュウ酸イオンが二酸化炭素として分解除去される。このために、還元剤を必要とせず熱分解により金属銀がそのまま得られ、不純物が残留しにくい点で、他の原料と比べて有利といえる。
The surface resistivity of the printing unit, for example, 10 5 Ω / □ is preferably (hereinafter, simply referred to as Omega) or more. Surface resistivity, 10 5 Omega least 10 9 Omega following static dissipative show antistatic properties below 10 9 Omega least 10 14 Omega. Furthermore, since the surface resistivity required for the radio wave permeability is 10 3 Omega above, the printing unit having a surface resistivity of more than 10 5 Omega also shows radio wave transmitting. Since the higher the surface resistivity of the printed portion is, the more preferable it is, there is no particular upper limit.
As the raw material of silver constituting the silver nanoparticles used in the ink according to the present embodiment, silver oxalate is preferable from the viewpoint that a metal is easily generated by thermal decomposition and impurities other than silver are less likely to be generated. Silver oxalate has a high silver content, and oxalate ions are decomposed and removed as carbon dioxide by heating. For this reason, metallic silver can be obtained as it is by thermal decomposition without the need for a reducing agent, and impurities are unlikely to remain, which is advantageous as compared with other raw materials.
本実施形態では、上記銀化合物をポリビニルピロリドン溶液中で加熱分解することで、ポリビニルピロリドンで表面が保護された銀ナノ粒子を製造する。ポリビニルピロリドンは、銀ナノ粒子の表面を保護する役割を果たすと共に、分散剤としても働く。
ポリビニルピロリドンで表面が保護された銀ナノ粒子とは、銀ナノ粒子の表面の少なくとも一部にポリビニルピロリドンを有している態様を表す。ポリビニルピロリドンの含有量は、分散液に対して０．１重量％以上３０重量％以下であることが好ましい。０．１重量％より少ない場合、銀同士が凝集してしまいナノ粒子を形成することが難しくなり、３０重量％より多い場合、銀ナノ粒子が高分子に絡まってしまいフィルタで目詰まりする恐れがある。銀ナノ粒子の表面に存在するポリビニルピロリドンは、ＴＧ−ＤＴＡ（熱重量示差熱）測定によって検出することが可能である。
In the present embodiment, the silver compound is thermally decomposed in a polyvinylpyrrolidone solution to produce silver nanoparticles whose surface is protected by polyvinylpyrrolidone. Polyvinylpyrrolidone plays a role of protecting the surface of silver nanoparticles and also acts as a dispersant.
The silver nanoparticles whose surface is protected by polyvinylpyrrolidone represents an embodiment in which polyvinylpyrrolidone is contained in at least a part of the surface of the silver nanoparticles. The content of polyvinylpyrrolidone is preferably 0.1% by weight or more and 30% by weight or less with respect to the dispersion liquid. If it is less than 0.1% by weight, silver will aggregate with each other and it will be difficult to form nanoparticles, and if it is more than 30% by weight, silver nanoparticles will be entangled with the polymer and may be clogged with the filter. is there. Polyvinylpyrrolidone present on the surface of silver nanoparticles can be detected by TG-DTA (thermogravimetric differential thermal) measurement.
本実施形態に係る銀ナノ粒子は、例えば、メジアン径（Ｄ５０）が１５ｎｍ以上１５０ｎｍ以下の範囲内であり、水やアルコールといった分散媒に分散可能である。なお、銀ナノ粒子のメジアン径（Ｄ５０）が１５ｎｍより小さいと視認性が低下し、銀ナノ粒子のメジアン径（Ｄ５０）が１５０ｎｍより大きいと分散性が低下することがある。
また、銀ナノ粒子の形状としては、球状、平板状、多角形状等のいずれか、又は複数の形状のものを含む。平板状の銀ナノ粒子は表面積が大きく、粒子が少量であっても視認性がよいことが期待される。また、銀ナノ粒子の形状が球状であると大きさが均一になりやすく、銀ナノ粒子が隙間なく並ぶことが期待できる。このため、球状の銀ナノ粒子も視認性がよいことが期待される。
The silver nanoparticles according to the present embodiment have, for example, a median diameter (D50) in the range of 15 nm or more and 150 nm or less, and can be dispersed in a dispersion medium such as water or alcohol. If the median diameter (D50) of the silver nanoparticles is smaller than 15 nm, the visibility may be lowered, and if the median diameter (D50) of the silver nanoparticles is larger than 150 nm, the dispersibility may be lowered.
Further, the shape of the silver nanoparticles includes one or more shapes such as spherical, flat plate, and polygonal. The flat plate-shaped silver nanoparticles have a large surface area and are expected to have good visibility even if the number of particles is small. Further, if the shape of the silver nanoparticles is spherical, the size tends to be uniform, and it can be expected that the silver nanoparticles are lined up without gaps. Therefore, it is expected that spherical silver nanoparticles also have good visibility.
銀ナノ粒子分散液の吸光スペクトルは、球状若しくは粒径の小さい銀ナノ粒子由来するものが４００ｎｍ付近にピークを有し、アスペクト比の大きい平板状銀ナノ粒子等に由来するものが６００〜１３００ｎｍ領域にブロードなピークを有することもある。換言すると、本実施形態に係る銀ナノ粒子が水を含む分散媒に分散された銀ナノ粒子分散液は、吸光スペクトルにおいて、３００ｎｍ以上５５０ｎｍ以下の波長領域に、球状又は粒径の小さい銀ナノ粒子に由来する第１のピークを有し、６００ｎｍ以上１３００ｎｍ以下の波長領域に、第１のピークよりもブロードであり、アスペクト比の大きい平板状の銀ナノ粒子等に由来する第２のピークを有していてもよい。なお、この吸光スペクトルは、例えば、紫外可視分光光度計（島津製作所社製、ＵＶ−２６００、透過モード、２５℃で測定）で測定を行うことができる。 As for the absorption spectrum of the silver nanoparticles dispersion, those derived from spherical or small particle size silver nanoparticles have a peak around 400 nm, and those derived from flat silver nanoparticles having a large aspect ratio are in the 600 to 1300 nm region. May have a broad peak. In other words, the silver nanoparticles dispersion liquid in which the silver nanoparticles according to the present embodiment are dispersed in a dispersion medium containing water has spherical or small particle size silver nanoparticles in a wavelength region of 300 nm or more and 550 nm or less in the absorption spectrum. It has a first peak derived from, and has a second peak derived from flat silver nanoparticles or the like, which is broader than the first peak and has a large aspect ratio, in the wavelength region of 600 nm or more and 1300 nm or less. You may be doing it. This absorption spectrum can be measured by, for example, an ultraviolet-visible spectrophotometer (manufactured by Shimadzu Corporation, UV-2600, transmission mode, measured at 25 ° C.).
インクにおける銀ナノ粒子の添加量は、例えば、１重量％以上５０重量％以下の範囲内であることが好ましい。なお、金属光沢が強くなることから、銀ナノ粒子の添加量は、１５重量％以上であることが特に好ましい。銀ナノ粒子の添加量が１重量％を下回ると印刷物としての視認性が低下し、５０重量％を上回ると分散性が低下することがある。
銀ナノ粒子の表面を保護するポリビニルピロリドンは、特に、その分子量に制限はないが、分子量１，０００，０００以下であることが好ましい。ポリビニルピロリドンの分子量が１，０００，０００より大きいと、溶液の粘度が高く扱いづらくなることがある。ポリビニルピロリドンの状態についての制限はなく、粉末製品を用いて溶液を作製しても、液体製品を用いてもよい。本実施形態において使用可能なポリビニルピロリドンとして、具体的には、日本触媒社製、ポリビニルドンＫ−３０、ポリビニルドンＫ−８５、ポリビニルドンＫ−３０Ｗ、ポリビニルドンＫ−８５Ｗ、第一工業製薬社製、ピッツコールＫ−３０（分子量４５，０００）、ピッツコールＫ−５０（分子量２５０，０００）、ピッツコールＫ−８０（分子量９００，０００）、ピッツコールＫ−８５（分子量１，０００，０００）等を挙げることができるがこの限りではない。
The amount of silver nanoparticles added to the ink is preferably in the range of, for example, 1% by weight or more and 50% by weight or less. The amount of silver nanoparticles added is particularly preferably 15% by weight or more because the metallic luster becomes stronger. If the amount of silver nanoparticles added is less than 1% by weight, the visibility as a printed matter may be lowered, and if it exceeds 50% by weight, the dispersibility may be lowered.
The molecular weight of polyvinylpyrrolidone that protects the surface of silver nanoparticles is not particularly limited, but is preferably 1,000,000 or less. If the molecular weight of polyvinylpyrrolidone is greater than 1,000,000, the viscosity of the solution may be high and it may be difficult to handle. There are no restrictions on the state of polyvinylpyrrolidone, and a solution may be prepared using a powder product or a liquid product may be used. Specific examples of the polyvinylpyrrolidone that can be used in the present embodiment include Polyvinylpyrrolidone K-30, Polyvinylpyrrolid K-85, Polyvinylpyrrolidone K-30W, Polyvinylpyrrolidone K-85W, manufactured by Nippon Shokubai Co., Ltd. , Pittscol K-30 (molecular weight 45,000), Pittscol K-50 (molecular weight 250,000), Pittscol K-80 (molecular weight 900,000), Pittscol K-85 (molecular weight 1,000,000) ) Etc., but this is not the case.
なお、ポリビニルピロリドンの分子量は、「重量平均分子量」で表記されることが多いため、上記を含め、本実施形態でのポリビニルピロリドンの分子量は特に断りがない限り、重量平均分子量とする。
重量平均分子量は、市販の測定装置で測定することが可能であり、例えば、ＧＣＰ（ゲル浸透クロマトグラフィー）法での測定が可能である。
なお、ＧＣＰ法は、ＥＳＣ（サイズ排除クロマトグラフィー）法とも呼ばれる。ＧＣＰ法であれば、測定する物質が高分子であっても、モノマー等が混合している場合（高分子単体の物質ではない場合）、測定時に検量線と併用して、分子量を推測することも可能である。
Since the molecular weight of polyvinylpyrrolidone is often expressed as "weight average molecular weight", the molecular weight of polyvinylpyrrolidone in the present embodiment including the above is the weight average molecular weight unless otherwise specified.
The weight average molecular weight can be measured by a commercially available measuring device, for example, by a GCP (gel permeation chromatography) method.
The GCP method is also called an ESC (size exclusion chromatography) method. In the GCP method, even if the substance to be measured is a polymer, if a monomer or the like is mixed (when it is not a substance of a single polymer), the molecular weight should be estimated by using it together with a calibration curve at the time of measurement. Is also possible.
本実施形態に係るインクに用いられる分散剤は、分散媒や粒子の大きさ等によって適宜選択する必要があるが、アニオン系分散剤、又はノニオン系分散剤が好ましい。具体的には、ポリオキシエチレンアルキルエーテルリン酸（塩）、ポリオキシエチレンアルキルエーテル硫酸塩、ポリオキシエチレンアルキルエーテル酢酸塩、ポリオキシエチレンアルキルエーテル琥珀酸塩、ポリオキシエチレンスチレン化フェニルエーテル、モノラウリン酸ポリグリセリル、モノミリスチン酸デカグリセリル、モノオレイン酸ポリグリセリル、ポリオキシエチレンフィロステロール、等が好ましい。具体的には、ＮＩＫＫＯＬ ＤＤＰ−８ＮＶ、ＤＤＰ−８、ＤＤＰ−１０、ＢＰＳ−１０、ＮＩＫＫＯＬ Ｄｅｃａｇｌｙｎ １−Ｌ、１−Ｍ、１−ＯＶ（日光ケミカルズ）、プライサーフ Ａ２１２Ｃ、Ａ２１５Ｃ、Ａ２０８Ｆ、Ｍ２０８Ｆ、Ａ２０８Ｎ、Ａ２０８Ｂ、Ａ２１０Ｂ、Ａ２１９Ｂ、ＤＢ−０１、ＡＬ、ＤＢＳ、ノイゲン ＥＡ−１５７、ＥＡ−１６７、ＥＡ−１７７、ＥＡ−１９７Ｄ、ＥＡ−２０７Ｄ（第一工業製薬）等を挙げることができるがこの限りではない。 The dispersant used in the ink according to the present embodiment needs to be appropriately selected depending on the dispersion medium, the size of particles, and the like, but an anion-based dispersant or a nonionic dispersant is preferable. Specifically, polyoxyethylene alkyl ether phosphate (salt), polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl ether acetate, polyoxyethylene alkyl ether amber salt, polyoxyethylene styrenated phenyl ether, monolaurine. Polyglyceryl acid, decaglyceryl monomyristate, polyglyceryl monooleate, polyoxyethylene phylosterol, and the like are preferable. Specifically, NIKKOL DDP-8NV, DDP-8, DDP-10, BPS-10, NIKKOL Decaglin 1-L, 1-M, 1-OV (Nikko Chemicals), Plysurf A212C, A215C, A208F, M208F, A208N, A208B, A210B, A219B, DB-01, AL, DBS, Neugen EA-157, EA-167, EA-177, EA-197D, EA-207D (Daiichi Kogyo Seiyaku) and the like can be mentioned. Not as long.
なお、本実施形態では、これらの分散剤を単独で、又は複数混合して用いてもよい。また、インクの組成物として用いる以外にも、銀ナノ粒子回収時に、分散剤を添加した分散液を遠心分離等で処理することで、粒子が凝集しにくく、再分散しやすい粒子が得られる。
インクにおける分散剤の添加量は、０．１重量％以上５重量％以下の範囲内であることが好ましい。分散剤の添加量が０．１重量％を下回ると分散安定性が低下し、５重量％を上回ると印刷適性が低下することがある。また、分散剤は、破泡剤として酸化珪素微粉末を含んでいてもよい。更に、分散剤は、エマルジョン化されていてもよい。
また、本実施形態に係るインクは、分散剤以外にも、例えば、色素、消泡剤、レベリング剤、硬化剤、等の添加剤を有してもよい。
In this embodiment, these dispersants may be used alone or in combination of two or more. In addition to being used as an ink composition, by treating the dispersion liquid to which the dispersant is added by centrifugation or the like at the time of recovering the silver nanoparticles, particles that are difficult to aggregate and easily redispersed can be obtained.
The amount of the dispersant added to the ink is preferably in the range of 0.1% by weight or more and 5% by weight or less. If the amount of the dispersant added is less than 0.1% by weight, the dispersion stability may be lowered, and if it exceeds 5% by weight, the printability may be lowered. Further, the dispersant may contain silicon oxide fine powder as a defoaming agent. Further, the dispersant may be emulsified.
In addition to the dispersant, the ink according to the present embodiment may contain additives such as a dye, an antifoaming agent, a leveling agent, and a curing agent.
本実施形態に係るインクが有する分散媒としては、例えば、水、エタノール、イソプロピルアルコール、グリセリン、プロピレングリコール、ポリエチレングリコール３００（平均分子量３００）等の各成分を挙げることができる。分散媒は、狙いとするインクの物性に合わせて上記成分を適宜混合して用いてよい。インクにおける上記成分の配合割合は特に限定するものではないが、インクジェット法ではノズルでのインクの乾燥を防止するために、例えば、グリセリン、プロピレングリコール、ポリエチレングリコール３００のような沸点１８０℃以上の多価アルコール１種以上を合計で、インクジェット印刷用インク（以下、単にインクジェットインクとも称する）中に１重量％以上５０重量％以下の範囲内で含有していることがより好ましい。インクジェットインク中における上記成分の含有量が１重量％より少ないと、インクの乾燥が起こりやすくなりノズルの目詰まりの原因となることがある。また、インクジェットインク中における上記成分の含有量が５０重量％を超えると、錠剤表面における印字表面の乾燥が遅くなりすぎて、印刷した錠剤同士が接触したときに未乾燥のインクがもう一方の錠剤に付着して汚れとなるといった不具合の原因となることがある。 Examples of the dispersion medium contained in the ink according to the present embodiment include water, ethanol, isopropyl alcohol, glycerin, propylene glycol, polyethylene glycol 300 (average molecular weight 300) and the like. As the dispersion medium, the above components may be appropriately mixed and used according to the physical properties of the target ink. The blending ratio of the above components in the ink is not particularly limited, but in the inkjet method, in order to prevent the ink from drying at the nozzle, for example, glycerin, propylene glycol, polyethylene glycol 300, etc. have a boiling point of 180 ° C. or higher. It is more preferable that one or more kinds of valent alcohols are contained in the ink for inkjet printing (hereinafter, also simply referred to as inkjet ink) in the range of 1% by weight or more and 50% by weight or less in total. If the content of the above components in the inkjet ink is less than 1% by weight, the ink tends to dry and may cause clogging of the nozzles. Further, when the content of the above components in the inkjet ink exceeds 50% by weight, the printing surface on the tablet surface dries too slowly, and when the printed tablets come into contact with each other, the undried ink becomes the other tablet. It may cause problems such as sticking to the ink and becoming dirty.
また、本実施形態のインクがインクジェットインクの場合、その粘度は室温（２５℃）下で２ｍＰａ・ｓ以上６ｍＰａ・ｓ以下の範囲内が好ましい。インクジェットインクの粘度が２ｍＰａ・ｓより低いと、インク吐出時に液滴が散ってサテライト（インクの飛び散り）ができやすくなる傾向がある。また、インクジェットインクの粘度が６ｍＰａ・ｓより高いと、吐出速度が遅くなり、印字も遅くなることがある。なお、上記単位「ｍＰａ・ｓ」は、「ｍＰｓ」とも表記される。 When the ink of the present embodiment is an inkjet ink, its viscosity is preferably in the range of 2 mPa · s or more and 6 mPa · s or less at room temperature (25 ° C.). If the viscosity of the inkjet ink is lower than 2 mPa · s, droplets tend to scatter when the ink is ejected, and satellites (ink scatter) tend to be easily formed. Further, if the viscosity of the inkjet ink is higher than 6 mPa · s, the ejection speed becomes slow and the printing may become slow. The unit "mPa · s" is also referred to as "mPs".
本実施形態に係るインクは、塗工面に金属光沢を呈する、即ち被印刷物上で金属光沢を示す。これにより、多角度測色を行うと、金属光沢の特徴の一つであるフリップフロップ性がみられる。ここで「フリップフロップ性」とは、メタリック感（金属光沢感）を数値化する方法の一つであり、視覚の方向性（見る位置）によって明度や色相の差があることをいう。多角度測色は、例えば、多角度測色計（ＢＹＫ−Ｇａｒｄｎｅｒ社製、ＢＹＫ−ｍａｃ、２５℃、Ｄ５０／２°）で測定を行うことができる。また、観察角度１５°、４５°、１１０°の各明度（Ｌ＊）の測定値から、下記（１）式によりフロップインデックス（Ｆｌｏｐ Ｉｎｄｅｘ）を計算で求めることができる。なお、下記（１）式における「Ｌ＊１５」、「Ｌ＊４５」及び「Ｌ＊１１０」は、観察角度１５°、４５°及び１１０°における各明度（Ｌ＊）の測定値をそれぞれ示している。
Ｆｌｏｐ Ｉｎｄｅｘ＝２．６９・（Ｌ＊１５−Ｌ＊１１０）１．１１／（Ｌ＊４５）０．８６
・・・（１）
The ink according to the present embodiment exhibits a metallic luster on the coated surface, that is, exhibits a metallic luster on the printed matter. As a result, when multi-angle colorimetric measurement is performed, flip-flop property, which is one of the characteristics of metallic luster, can be seen. Here, "flip-flop property" is one of the methods for quantifying the metallic feeling (metallic luster feeling), and means that there is a difference in brightness and hue depending on the visual direction (viewing position). The multi-angle color measurement can be performed by, for example, a multi-angle colorimeter (BYK-Gardner, BYK-mac, 25 ° C., D50 / 2 °). Further, the flop index (Flop Index) can be calculated from the measured values of the brightness (L *) at the observation angles of 15 °, 45 °, and 110 ° by the following equation (1). In addition, "L * 15 ", "L * 45 " and "L * 110 " in the following equation (1) indicate the measured values of the respective brightness (L *) at the observation angles of 15 °, 45 ° and 110 °, respectively. ing.
Flop Index = 2.69 · (L * 15- L * 110 ) 1.11 / (L * 45 ) 0.86
... (1)
なお、上記（１）式は、特開２００８−１２６１２６号公報に開示されているフロップインデックス計算式を参考にした。
フロップインデックスはフロップ感を数値化したものであり、値が大きいほど金属光沢が強くみえるため、計算値が４以上である場合に金属光沢があると判断する。
For the above formula (1), the flop index calculation formula disclosed in JP-A-2008-126126 was referred to.
The flop index is a numerical value of the flop feeling, and the larger the value, the stronger the metallic luster appears. Therefore, when the calculated value is 4 or more, it is judged that the metallic luster is present.
（印刷方法）
本実施形態に係るインクは、印刷方法は問わず、例えば、インクジェットやバーコート、スピンコートといった手法により印刷、塗工が可能である。なかでもインクジェット法は、版を用いることなく画像等が印刷でき、形状及び性状が種々な物に印刷可能であるうえ、少量のインクで印刷されることから印刷部の厚みが薄くなり、高い表面抵抗率が期待されることから好ましい。
また、被印刷物は、印刷部の保護のために、印刷部の上にトップコートを有していてもよい。
(Printing method)
The ink according to the present embodiment can be printed and coated by a method such as inkjet, bar coating, or spin coating regardless of the printing method. Among them, the inkjet method can print images without using a plate, can print on various shapes and properties, and prints with a small amount of ink, so the thickness of the printed part becomes thin and the surface is high. It is preferable because the resistivity is expected.
Further, the printed matter may have a top coat on the printed portion in order to protect the printed portion.
（被印刷物）
本実施形態に係る被印刷物は、印刷基材と、その印刷基材の印刷面に、上記のインクを使用して印刷された印刷部を備える。
印刷基材の印刷面は、非導電性を有することが好ましい。印刷基材を構成する材料としては、例えば、ポリエチレンテレフタレート（ＰＥＴ）等のポリエステル、ビニル樹脂、ガラス、紙、等を挙げることができる。インクの密着性向上、又はその他の目的のために、印刷基材の印刷面を構成する表面層が親水化処理等の表面処理を施した被印刷物を用いてもよい。印刷基材は、複数の積層体から構成されていてもよい。
(Printed matter)
The printed matter according to the present embodiment includes a printing base material and a printing portion printed on the printing surface of the printing base material using the above ink.
The printed surface of the printing substrate is preferably non-conductive. Examples of the material constituting the printing substrate include polyester such as polyethylene terephthalate (PET), vinyl resin, glass, and paper. For the purpose of improving ink adhesion or for other purposes, a printed matter in which the surface layer constituting the printed surface of the printing substrate has been subjected to a surface treatment such as a hydrophilic treatment may be used. The printing substrate may be composed of a plurality of laminates.
本実施形態の被印刷物は、印刷基材の印刷面に銀ナノ粒子をインク化して印刷することで、印刷部が金属光沢を示す。また、銀ナノ粒子の表面がポリビニルピロリドンで保護されているため、印刷部が低い導電性の性状となる。また、印刷部に存在する銀ナノ粒子は、ポリビニルピロリドンによって表面が保護されているため、銀ナノ粒子同士が融着しないか融着し難い。すなわち、粒径がナノメートルレベルまで微細化された銀ナノ粒子で覆われた印刷部の表面は金属光沢を示すが、銀ナノ粒子同士が融着していないため低い導電性を示す。
このような印刷部を被印刷物に設けることが可能なことで、電波を透過する必要のある部材への印刷や、内部回路の破壊防止に繋がることが期待される。近年、スマートフォンやセンサー用途で必要とされている電磁波を透過する、金属調の意匠膜等も作製可能である。
In the printed matter of the present embodiment, silver nanoparticles are converted into ink and printed on the printed surface of the printing substrate, so that the printed portion exhibits a metallic luster. Further, since the surface of the silver nanoparticles is protected by polyvinylpyrrolidone, the printed portion has a low conductive property. Further, since the surface of the silver nanoparticles present in the printed portion is protected by polyvinylpyrrolidone, the silver nanoparticles do not fuse with each other or are difficult to fuse with each other. That is, the surface of the printed portion covered with silver nanoparticles whose particle size has been refined to the nanometer level exhibits metallic luster, but exhibits low conductivity because the silver nanoparticles are not fused to each other.
By providing such a printed portion on the printed matter, it is expected that it will lead to printing on a member that needs to transmit radio waves and prevention of destruction of the internal circuit. In recent years, it is possible to produce a metallic design film or the like that transmits electromagnetic waves required for smartphones and sensors.
以下に、実施例として、銀ナノ粒子の製造、インク化、印刷等の方法、印刷部の評価等を示す。しかし、本発明はこれらに限定されるものではない。 Hereinafter, as examples, methods for producing silver nanoparticles, inking, printing, etc., evaluation of the printing unit, and the like are shown. However, the present invention is not limited thereto.
＜実施例１＞
〔シュウ酸銀の合成〕
シュウ酸二水和物（関東化学社製）９．９２ｇに蒸留水６０ｍＬを加え加温しながら溶解させた。その溶液を１１０℃のオイルバス中で攪拌しながら、当該溶液中に、硝酸銀（関東化学社製）２６．７ｇに２０ｍＬの蒸留水を加え加温しながら溶解させたものを加えて、１時間加熱攪拌を続けた。析出したシュウ酸銀を自然ろ過で回収し、回収したシュウ酸銀を、熱水２００ｍＬ、エタノール（関東化学社製）５０ｍＬでろ過洗浄した後、遮光デシケーター内で減圧しながら室温乾燥した。こうして得たシュウ酸銀の収量は、２１．６ｇ（収率９０．４％）であった。
<Example 1>
[Silver oxalate synthesis]
60 mL of distilled water was added to 9.92 g of oxalic acid dihydrate (manufactured by Kanto Chemical Co., Inc.) and dissolved while heating. While stirring the solution in an oil bath at 110 ° C., add 20 mL of distilled water to 26.7 g of silver nitrate (manufactured by Kanto Chemical Co., Inc.) and dissolve it while heating, and add the solution for 1 hour. Heating and stirring were continued. The precipitated silver oxalate was recovered by natural filtration, and the recovered silver oxalate was filtered and washed with 200 mL of hot water and 50 mL of ethanol (manufactured by Kanto Chemical Co., Inc.), and then dried at room temperature while reducing the pressure in a light-shielding desiccator. The yield of silver oxalate thus obtained was 21.6 g (yield 90.4%).
〔銀ナノ粒子の合成〕
水４．０ｇにポリビニルピロリドンとしてピッツコールＫ−３０（第一工業製薬社製）２．４ｇを添加し水溶液を調製した分散媒に、上述の工程で得たシュウ酸銀０．４８ｇを加え、８０℃のオイルバスで加熱攪拌した。その加熱攪拌を５時間実施することで灰色に変化した分散液を得た。その分散液について、放熱したところに水４０ｍＬを加え、遠心分離（ベックマン・コールター社製、ＡｖａｎｔｉＨＰ−２６ＸＰ、１５、０００ｒｐｍ３０分間）により分離することで、灰色固形物０．３５ｇを得た。この灰色固形物が本実施例に係る銀ナノ粒子、即ちポリビニルピロリドンで表面が保護された銀ナノ粒子である。
なお、ピッツコールＫ−３０の重量平均分子量は４５，０００であった。
[Synthesis of silver nanoparticles]
To a dispersion medium prepared by adding 2.4 g of Pitzcol K-30 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) as polyvinylpyrrolidone to 4.0 g of water, 0.48 g of silver oxalate obtained in the above step was added. The mixture was heated and stirred in an oil bath at 80 ° C. The heating and stirring was carried out for 5 hours to obtain a dispersion liquid that turned gray. About the dispersion, 40 mL of water was added to the place where heat was dissipated, and the mixture was separated by centrifugation (AvantiHP-26XP, 15,000 rpm for 30 minutes, manufactured by Beckman Coulter) to obtain 0.35 g of a gray solid. This gray solid is the silver nanoparticles according to the present embodiment, that is, the silver nanoparticles whose surface is protected by polyvinylpyrrolidone.
The weight average molecular weight of Pittscol K-30 was 45,000.
〔銀ナノ粒子の観察〕
上記工程により得られた銀ナノ粒子を、走査型電子顕微鏡（日立ハイテクノロジー社製、ＳＥＭ Ｓ−４８００）を用いてＳ−ＴＥＭモード（加速電圧３０ｋＶ）で観察したところ、粒径が１０〜１０００ｎｍ程度の球状又は平板状粒子が観察された。その結果を図１に示す。より詳しくは、図１は、実施例１で得た銀ナノ粒子の水溶媒分散液を基板（銅メッシュ・マイクログリッド）に垂らし乾燥させた後に観察した銀ナノ粒子の走査型電子顕微鏡像である。
[Observation of silver nanoparticles]
When the silver nanoparticles obtained by the above steps were observed in S-TEM mode (acceleration voltage 30 kV) using a scanning electron microscope (SEM S-4800 manufactured by Hitachi High Technology), the particle size was 10 to 1000 nm. Spherical or flat particles of some degree were observed. The result is shown in FIG. More specifically, FIG. 1 is a scanning electron microscope image of silver nanoparticles observed after the aqueous solvent dispersion of silver nanoparticles obtained in Example 1 was dripped on a substrate (copper mesh / microgrid) and dried. ..
次に、得られた銀ナノ粒子について、溶媒への分散性を評価した。その評価結果として、得られた銀ナノ粒子が水に良好に分散したことを確認した。すなわち、その水分散液の動的光散乱粒度測定（日機装社製、Ｎａｎｏｔｒａｃ ＵＰＡ−ＥＸ１５０）により、得られた銀ナノ粒子は平均粒径２３ｎｍで良好に分散していることがわかった。その結果を図２に示す。また、図２に示した実線は、累積度数（％）を示している。
上記のようにして得られた銀ナノ粒子０．１ｇを、１０ｇの水に分散して作製した水分散液の吸光スペクトル（島津製作所社製、紫外可視分光光度計 ＵＶ−２６００、透過モード）を図３に示す。図３から、実施例１に係る銀ナノ粒子分散液は、吸光スペクトルにおいて、３００ｎｍ以上５５０ｎｍ以下の波長領域に第１のピークを有し、６００ｎｍ以上１３００ｎｍ以下の波長領域に、第１のピークよりもブロードな第２のピークを有していることがわかった。
Next, the dispersibility of the obtained silver nanoparticles in a solvent was evaluated. As a result of the evaluation, it was confirmed that the obtained silver nanoparticles were well dispersed in water. That is, by dynamic light scattering particle size measurement of the aqueous dispersion (Nanotrac UPA-EX150, manufactured by Nikkiso Co., Ltd.), it was found that the obtained silver nanoparticles were well dispersed with an average particle size of 23 nm. The result is shown in FIG. The solid line shown in FIG. 2 indicates the cumulative frequency (%).
The absorption spectrum of the aqueous dispersion prepared by dispersing 0.1 g of the silver nanoparticles obtained as described above in 10 g of water (manufactured by Shimadzu Corporation, ultraviolet visible spectrophotometer UV-2600, transmission mode). It is shown in FIG. From FIG. 3, the silver nanoparticle dispersion liquid according to Example 1 has a first peak in a wavelength region of 300 nm or more and 550 nm or less in an absorption spectrum, and has a first peak in a wavelength region of 600 nm or more and 1300 nm or less from the first peak. Was also found to have a broad second peak.
〔インクジェットインクの調製〕
水７．０ｇ、グリセリン２．０ｇ、イソプロピルアルコール１．０ｇを混合した溶媒に、分散剤であるＮＩＫＫＯＬ Ｄｅｃａｇｌｙｎ １−Ｌ（日光ケミカルズ社製）０．５ｇを溶解させた分散媒を作製し、その分散媒に対し、上述の工程で得た銀ナノ粒子４．０ｇを分散させよく攪拌した後、シリンジフィルター（Ｗｈａｔｍａｎ社製、２５ｍｍ ＧＤ／Ｘシリンジフィルター（ＧＦ／Ｂ １．０μｍ））に通し、インクジェット印刷用のインク、即ちインクジェットインクを調製した。この場合、分散媒の合計量１０ｇに対して、グリセリン２ｇのため、グリセリンの重量％は２０％となる。また、分散媒１０ｇに対して銀ナノ粒子４ｇのため、銀ナノ粒子の重量％は４０％となる。以下同様に計算する。
なお、インクジェットインクの粘度は４ｍＰｓであった。また、グリセリンの沸点は、２９０℃であった。
インクの粘度測定は、山一電機社製 ＶＭ−１Ｇ−Ｌ／ＤＤ−１Ａを用いて測定時のインク液温２５℃で測定を行った。
[Preparation of inkjet ink]
A dispersion medium was prepared by dissolving 0.5 g of the dispersant NIKKOL Decaglin 1-L (manufactured by Nikko Chemicals Co., Ltd.) in a solvent obtained by mixing 7.0 g of water, 2.0 g of glycerin, and 1.0 g of isopropyl alcohol. 4.0 g of silver nanoparticles obtained in the above step was dispersed in a dispersion medium and stirred well, and then passed through a syringe filter (25 mm GD / X syringe filter (GF / B 1.0 μm) manufactured by Whatman). An ink for inkjet printing, that is, an inkjet ink was prepared. In this case, since 2 g of glycerin is used with respect to 10 g of the total amount of the dispersion medium, the weight% of glycerin is 20%. Further, since the silver nanoparticles are 4 g with respect to 10 g of the dispersion medium, the weight% of the silver nanoparticles is 40%. The same calculation is performed below.
The viscosity of the inkjet ink was 4 mPs. The boiling point of glycerin was 290 ° C.
The viscosity of the ink was measured using a VM-1GL / DD-1A manufactured by Yamaichi Electric Co., Ltd. at an ink liquid temperature of 25 ° C. at the time of measurement.
〔インクジェット印刷〕
上記工程により調整したインクジェットインクを用いて、印刷テストを行った。この印刷テストでは、ノズル数６のドロップオンデマンド型インクジェットヘッドを用い、１ドロップ１０ｐＬの印刷ドロップ量にてテストパターンを印刷した。印刷内容（印刷画像）には、５ｃｍ×５ｃｍの正方形を塗りつぶした画像を用いた。被印刷物の印刷基材としてコロナ処理を行った７５μｍＰＥＴフィルム（ルミラーＴ６０、東レ社製）を用いたところ、印刷した画像には銀色の強い光沢がみられた。
[Inkjet printing]
A printing test was performed using the inkjet ink prepared by the above step. In this printing test, a drop-on-demand inkjet head with 6 nozzles was used to print a test pattern with a print drop amount of 10 pL per drop. As the print content (printed image), an image filled with a 5 cm × 5 cm square was used. When a corona-treated 75 μm PET film (Lumirror T60, manufactured by Toray Industries, Inc.) was used as the printing base material of the printed matter, a strong silver gloss was observed in the printed image.
得られた印刷部に対し、表面抵抗率抵抗率計（ＨｉｒｅｓｔａＩＰ ＭＣＰ−ＨＴ２６０、三菱化学社製）を用いて表面抵抗率を測定した。測定条件は、ＰＲＯＢＥ ＴＹＰＥ：ＨＲＳ、ＳＵＰＰＬＹ ＶＯＬＴＡＧＥ：１０Ｖで測定を行った。その結果、表面抵抗率は５．０１×１０１０Ωであった。
得られた印刷部に対し、分光光度計（米国 Ｘ−Ｒｉｔｅ社製「Ｘ−Ｒｉｔｅ Ｔ−５３０」）を用いて色度（Ｌ＊ａ＊ｂ＊表色系）を測定した。測定結果を表１に示す。
The surface resistivity of the obtained printed portion was measured using a surface resistivity resistivity meter (HirestaIP MCP-HT260, manufactured by Mitsubishi Chemical Corporation). The measurement conditions were PROBE TYPE: HRS and SUPPLY VOLTAGE: 10V. As a result, the surface resistivity was 5.01 × 10 10 Ω.
The chromaticity (L * a * b * color system) of the obtained printed portion was measured using a spectrophotometer (“X-Rite T-530” manufactured by X-Rite, USA). The measurement results are shown in Table 1.
なお、Ｌ＊ａ＊ｂ＊表色系とは、ＣＩＥ（国際照明委員会）が推奨した、次の３つの値を使った座標で表した表色系である。Ｌ＊は明るさを示し、０から１００まで数値が大きいほど明るくなる。
色みはａ＊、ｂ＊で表し、ａ＊、ｂ＊ともに０の場合は無彩色となる。ａ＊がプラスの方向になるほど赤みが強くなり、マイナスの方向になるほど緑みが強くなる。また、ｂ＊がプラスの方向になるほど黄みが強くなり、マイナスの方向になるほど青みが強くなる。なお、この３つの軸が直交して交わる点は、Ｌ＊＝５０、ａ＊＝０、ｂ＊＝０である。
The L * a * b * color system is a color system recommended by the CIE (International Commission on Illumination) and expressed in coordinates using the following three values. L * indicates the brightness, and the larger the value from 0 to 100, the brighter the image.
The tint is represented by a * and b *, and when both a * and b * are 0, the color is achromatic. The more positive the a * is, the stronger the redness is, and the more negative the a * is, the stronger the greenness. Further, the more positive the direction of b *, the stronger the yellowness, and the more negative the direction, the stronger the bluishness. The points where these three axes intersect at right angles are L * = 50, a * = 0, and b * = 0.
＜実施例２＞
実施例１で用いたインクに対し、分散剤としてＮＩＫＫＯＬ Ｄｅｃａｇｌｙｎ １−Ｍ（日光ケミカルズ社製）０．５ｇを用いた以外は、実施例１と同様にインクを調製した。こうして調製した実施例２に係るインクを用いて印刷テストを行ったところ、印刷部は金属光沢を示し、表面抵抗率は３．７９×１０１０Ωであった。
<Example 2>
An ink was prepared in the same manner as in Example 1 except that 0.5 g of NIKKOL Decaglin 1-M (manufactured by Nikko Chemicals Co., Ltd.) was used as a dispersant with respect to the ink used in Example 1. When a printing test was performed using the ink according to Example 2 prepared in this way, the printed portion showed a metallic luster, and the surface resistivity was 3.79 × 10 10 Ω.
＜実施例３＞
被印刷物の印刷基材として、ＰＥＴフィルムではなくキャストコート紙（ミラーコート・プラチナ、王子製紙社製）を用いた以外は実施例１と同様に印刷テストを行ったところ、印刷部は金属光沢を示し、表面抵抗率は３．３８×１０９Ωであった。
得られた印刷部を、走査型電子顕微鏡（日立ハイテクノロジー社製、ＳＥＭ Ｓ−４８００）を用いてＳＥＭモード（加速電圧５ｋＶ）で観察したところ、銀ナノ粒子は融着しておらず、球状、平板状、又は多面体状の形状を保っている様子がみられた。その結果を図４に示す。
また、印刷部に対し多角度測色（ＢＹＫ−Ｇａｒｄｎｅｒ社製、ＢＹＫ−ｍａｃ）を行ったところ、角度によってＬ＊の値に変化があり、フロップ性がみられた。結果を表２に示す。また、この時のフロップインデックスは５．２２となった。
なお、実施例２で用いたインクを用いても、実施例３と同様のフリップフロップ性を示した。
<Example 3>
When a printing test was performed in the same manner as in Example 1 except that cast coated paper (mirror coated platinum, manufactured by Oji Paper Co., Ltd.) was used as the printing base material for the printed matter, the printed portion had a metallic luster. shows, the surface resistivity was 3.38 × 10 9 Ω.
When the obtained printed portion was observed in SEM mode (acceleration voltage 5 kV) using a scanning electron microscope (SEM S-4800 manufactured by Hitachi High Technology Co., Ltd.), the silver nanoparticles were not fused and were spherical. It was observed that the shape was maintained in a flat plate shape or a polyhedron shape. The result is shown in FIG.
Further, when multi-angle color measurement (BYK-mac manufactured by BYK-Gardner) was performed on the printed portion, the value of L * changed depending on the angle, and the flop property was observed. The results are shown in Table 2. The flop index at this time was 5.22.
Even when the ink used in Example 2 was used, the same flip-flop property as in Example 3 was exhibited.
＜比較例１＞
実施例１で用いたインクに対し、分散剤を用いなかった以外は、実施例１と同様にインクを調整した。印刷テストを行ったところ、印刷部の印刷濃度が薄く、金属光沢を示さなかった。これは、分散剤を添加しなかったことで、銀ナノ粒子の分散性が不十分となり凝集し、ノズルから吐出される銀ナノ粒子量が減少したためと考えられる。
<Comparative example 1>
With respect to the ink used in Example 1, the ink was adjusted in the same manner as in Example 1 except that a dispersant was not used. When a printing test was performed, the printing density of the printed portion was low and no metallic luster was exhibited. It is considered that this is because the dispersibility of the silver nanoparticles became insufficient and aggregated due to the absence of the dispersant, and the amount of silver nanoparticles discharged from the nozzle decreased.
以上説明したように、本発明では、ポリビニルピロリドンで表面が保護された銀ナノ粒子をインク化して印刷することで、印刷部が金属光沢を示し、かつ低い導電性である被印刷物を提供することができる。このような印刷部を設けることが可能なことで、電波を透過する必要のある部材への印刷や、内部回路の破壊防止が期待され、幅広く電子機器へ使用できる。 As described above, in the present invention, by printing silver nanoparticles whose surface is protected by polyvinylpyrrolidone as ink, it is possible to provide a printed matter in which the printed portion exhibits metallic luster and has low conductivity. Can be done. By providing such a printing unit, it is expected that printing on a member that needs to transmit radio waves and prevention of destruction of an internal circuit can be expected, and it can be widely used in electronic devices.
Claims (6)
上記インクの表面抵抗率が１０５Ω／□以上であることを特徴とするメタリックインク。 An ink containing silver nanoparticles whose surface is protected by polyvinylpyrrolidone, a dispersant, and a dispersion medium.
Metallic ink, wherein the surface resistivity of the ink is 10 5 Ω / □ or more.
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