JP2017165830A - Cleaning fluid and cleaning method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning fluid and a cleaning method for which cleaning effects for a metal nano ink can be obtained.SOLUTION: The cleaning fluid contains an organic solvent, water, an acid, hydrogen peroxide and a dispersant for dispersing metal nanoparticles, the added amount of the organic solvent is less than 80 wt.%, the added amount of the dispersant is less than 5 wt.%, the added amount of the acid is over 1.0 wt.% and the added amount of hydrogen peroxide is over 0.3 wt.%.SELECTED DRAWING: None

Description

  The present case relates to a cleaning liquid and a cleaning method.

  Metal nano inks containing metal nanoparticles are used. In the coating apparatus for applying the metal nano ink, since the metal nano ink adheres to the flow path, it is preferable to perform a cleaning process on the flow path periodically or as needed. However, when metal nano ink is washed, clogging due to aggregation of metal nanoparticles may occur.

JP 2007-191524 A

  For example, Patent Document 1 discloses a cleaning composition. However, with the cleaning composition disclosed in Patent Document 1, it is difficult to clean the metal nano ink.

  The present invention has been made in view of the above problems, and an object thereof is to provide a cleaning liquid and a cleaning method capable of obtaining a cleaning effect on the metal nano ink.

  The cleaning liquid according to the present invention includes an organic solvent, water, an acid, hydrogen peroxide, and a dispersant for dispersing the metal nanoparticles, and the amount of the organic solvent added is less than 80% by weight, The addition amount of the dispersant is less than 5% by weight, the addition amount of the acid is more than 1.0% by weight, and the addition amount of the hydrogen peroxide is more than 0.3% by weight. .

  The amount of hydrogen peroxide added may be 0.5 wt% or more and 10 wt% or less. The addition amount of the acid may be 2 wt% or more and 30 wt% or less. The acid may contain any of sulfuric acid, hydrochloric acid, nitric acid, formic acid, sulfamic acid, p-toluenesulfonic acid, citric acid, and gluconic acid. The addition amount of the organic solvent may be 5% by weight or more and 70% by weight or less. The organic solvent may contain any of butyl diglycol, isopropyl alcohol, propylene glycol, γ-butyrolactone, N, N-dimethylisobutyramide, acetone, and 1,3-dimethyl-2-imidazolidinone. . The amount of the dispersant added may be 0.01% by weight or more and 3% by weight or less.

  The cleaning method according to the present invention includes a step of cleaning metal nanoparticles using the cleaning liquid. The metal nanoparticles may be copper having a nano-order particle size.

  According to the cleaning liquid and the cleaning method of the present invention, a cleaning effect on the metal nano ink can be obtained.

  Prior to the description of the cleaning liquid and the cleaning method according to the embodiment, an outline of the metal nano ink that is a cleaning target will be described.

  The metal nano ink is a metal particle dispersion liquid in which metal nanoparticles having a nano-order diameter are dispersed. The metal nanoparticles are not particularly limited, but are copper particles, gold particles, silver particles, nickel particles, tin particles, and the like. As an example, the particle diameter of the metal nanoparticles is 1 nm to 100 nm. As the dispersion medium, for example, a protic dispersion medium and an aprotic polar dispersion medium having a relative dielectric constant of 30 or more can be used. As the dispersant, for example, a compound having a molecular weight of 200 to 100,000 having at least one acidic functional group or a salt thereof can be used.

An example of the metal nano ink is shown below.
Metal nano ink: Copper nano ink Copper nano particle: Center particle diameter 20nm, 45wt%
Dispersion medium: Diethylene glycol (protic solvent)
Dispersant: PVP-K25, 2.0 wt%

  Such metal nano ink is applied to a substrate or the like using a coating apparatus. Examples of the coating apparatus include printing apparatuses such as an inkjet printing apparatus, a screen printing apparatus, a gravure printing apparatus, a gravure offset printing apparatus, and a flexographic printing apparatus. In these coating apparatuses, since the metal nano ink adheres to the flow path, it is preferable to perform a cleaning process on the flow path periodically or as needed. However, when the metal nano ink is to be washed, clogging due to aggregation or the like may occur.

  Since metal nanoparticles of the object to be cleaned are as small as 1 nm to 100 nm, for example, in conventional cleaning liquids, before the cleaning progresses, a solvent shock (a metal nanoparticle obtained by adding a solvent having a property different from that of the dispersion medium of the metal fine particle dispersion liquid). There is a possibility that the metal nanoparticles are aggregated and precipitated due to the particle agglomeration phenomenon, and the inkjet head (nozzle diameter of several tens to several hundreds μm) is clogged.

  The present inventor has found a cleaning liquid and a cleaning method capable of obtaining a cleaning effect on the metal nano ink through intensive studies. Hereinafter, the cleaning liquid and the cleaning method according to the embodiment will be described.

(Embodiment)
The cleaning liquid according to one embodiment includes an organic solvent, water, an acid, hydrogen peroxide, and a dispersant for dispersing the metal nanoparticles, and the addition amount of the organic solvent is less than 80% by weight. Is less than 5% by weight, acid is added in excess of 1.0% by weight, and hydrogen peroxide is added in excess of 0.3% by weight.

Since the cleaning liquid according to the present embodiment contains hydrogen peroxide having an oxidizing action so as to exceed 0.3% by weight, the metal nanoparticles can be oxidized. First, in accordance with the following formula (1), active oxygen is generated by the decomposition of hydrogen peroxide. Next, according to the following formula (2), the metal nanoparticles are oxidized by active oxygen. In the following formula (2), an oxidation reaction of copper is shown as an example.
H ₂ O ₂ → H ₂ O + (O) (1)
Cu + (O) → CuO (2)

Next, since the cleaning liquid according to the present embodiment contains an acid exceeding 1.0% by weight, the dissolution rate of the metal oxide can be improved. As an example, when copper is used as the metal nanoparticles and sulfuric acid is used as the acid, the dissolution rate of copper oxide can be improved according to the following formula (3).
CuO + H ₂ SO ₄ → CuSO ₄ + H ₂ O (3)

  Moreover, since the washing | cleaning liquid which concerns on this embodiment contains the organic solvent, it can suppress aggregation of a metal nanoparticle. On the other hand, dissolution of the metal nanoparticles can be promoted by providing an upper limit (less than 80% by weight) for the amount of organic solvent added. Moreover, since the washing | cleaning liquid which concerns on this embodiment contains water, it can improve the solubility of a metal. Moreover, since the washing | cleaning liquid which concerns on this embodiment contains the dispersing agent which disperse | distributes a metal nanoparticle, aggregation, precipitation, etc. of a metal nanoparticle can be delayed. On the other hand, coagulation due to excessive addition of the polymer compound can be suppressed by providing an upper limit (less than 5% by weight) to the amount of dispersant added.

  From the above, according to the cleaning liquid according to the present embodiment, the metal nanoparticles can be dissolved and aggregation of the metal nanoparticles can be suppressed, so that a cleaning effect on the metal nano ink can be obtained.

  The organic solvent is not particularly limited, but examples include water such as alcohol, glycol, glycol ether, ketone, lactone, lactam, cyclic ether, amide, nitrile, oxazolidinone, imidazolidinone, sulfone, sulfoxide, and carbonate. An organic solvent can be used.

  As alcohol, isopropyl alcohol, methanol, ethanol, isopropanol, n-butyl alcohol, n-amyl alcohol, n-hexyl alcohol, 2-methylpentanol, 2-hexyl alcohol, 2-ethylbutyl alcohol 2-heptyl alcohol, heptanol-3,2-ethylhexyl alcohol, benzyl alcohol, 2-octanol, 3-methoxy-3-methylbutanol and the like can be used.

  As glycol or glycol ether, ethylene glycol, ethylene glycol monomethyl ether, triethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether (butyl diglycol), propylene glycol, propylene Glycol monomethyl ether, propylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol mono-tert-butyl ether, dipropylene glycol monomethyl ether, 1,3-butylene glycol, diethylene glycol dimethyl ether, diethylene glycol di Chirueteru, triethylene glycol dimethyl ether, or the like can be used triethylene glycol diethyl ether.

  As the ketone, acetone, diethyl ketone, acetophenone, methyl ethyl ketone, cyclohexanone, cyclopentanone, diacetone alcohol, or the like can be used.

  As the lactone, β-propiolactone, β-butyrolactone, γ-butyrolactone, γ-valerolactone, δ-valerolactone, and the like can be used.

  As the lactam, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-hydroxymethyl-2-pyrrolidone and the like can be used.

  Tetrahydrofuran, tetrahydropyran, etc. can be used as the cyclic ether.

  As the amide, N, N-dimethylisobutyramide, N, N-dimethylformamide, N-methylformamide, N, N-dimethylacetamide, N, N-dimethylpropionamide and the like can be used.

  As the nitrile, acetonitrile, propionitrile, butyronitrile, acrylonitrile, methacrylonitrile, benzonitrile and the like can be used.

  As oxazolidinone, N-methyl-2-oxazolidinone, 3,5-dimethyl-2-oxazolidinone, and the like can be used.

  As the imidazolidinone, 1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, 1,3-diisopropyl-2-imidazolidinone and the like can be used.

  As the sulfone, dimethylsulfone, diethylsulfone, bis (2-hydroxyethyl) sulfone, or the like can be used.

  As the sulfoxide, dimethyl sulfoxide, sulfolane, butyl sulfone, 3-methyl sulfolane, 2,4-dimethyl sulfolane and the like can be used.

  As the carbonate, ethylene carbonate, propion carbonate or the like can be used.

  Note that as the organic solvent, it is preferable to use butyl diglycol, isopropyl alcohol, propylene glycol, γ-butyrolactone, N, N-dimethylisobutyramide, acetone, 1,3-dimethyl-2-imidazolidinone, and the like. This is because the dispersion stability is high with respect to the metal nanoparticles and the solvent is generally used for the metal nano ink, and therefore, aggregation due to a solvent shock hardly occurs when the metal nano ink is washed.

  The addition amount of the organic solvent is preferably 5% by weight or more. This is because aggregation of metal nanoparticles can be suppressed. The addition amount of the organic solvent is more preferably 10% by weight or more. On the other hand, the addition amount of the organic solvent is preferably 70% by weight or less. This is because dissolution of metal nanoparticles can be promoted. The addition amount of the organic solvent is more preferably 60% by weight or less.

  Next, the dispersant is not particularly limited as long as it has an effect of dispersing the metal nanoparticles. As an example, a compound having at least one acidic functional group and having a molecular weight of 200 or more and 100,000 or less or a salt thereof is used. be able to. The acidic functional group of the dispersant is acidic, that is, a functional group having proton donating properties, such as a phosphoric acid group, a phosphonic acid group, a sulfonic acid group, a sulfuric acid group, and a carboxyl group. A compound having a phosphate group and a molecular weight of about 1500 (manufactured by Big Chemie, trade name “DISPERBYK (registered trademark) -111”), a compound having a phosphate group and a molecular weight of tens of thousands (“DISPERBYK (registered trademark) -2001”), Low molecular weight polyaminoamide and acid polymer salt (BIC Chemie, trade name “ANTI-TERRA (registered trademark) -U100”), alkylammonium salt of a compound having a phosphate group with a molecular weight of 1000 to 2000 (BIC Chemie, (Trade name “DISPERBYK (registered trademark) -180”), a polymer having a phosphate group having a molecular weight of about 20,000 and having a spherical structure (trade name “DISPERBYK (registered trademark) -2155” manufactured by Big Chemie), polyvinylpyrrolidone, Fluorosurfactant (manufactured by Neos, trade name “Futaji Cement 208G "), or the like can be used.

  The addition amount of the dispersant is preferably 0.01% by weight or more. This is because the dispersion of the metal nanoparticles can be further promoted. Further, the addition amount of the dispersant is more preferably 0.02% by weight or more. On the other hand, it is preferable that the addition amount of a dispersing agent is 3 weight% or less. This is because aggregation of metal nanoparticles can be further suppressed. Further, the addition amount of the dispersant is more preferably 1% by weight or less.

  The amount of hydrogen peroxide added to the cleaning liquid is preferably 0.5% by weight or more. This is because dissolution of metal nanoparticles is promoted. The amount of hydrogen peroxide added to the cleaning liquid is more preferably 1% by weight or more. On the other hand, the amount of hydrogen peroxide added to the cleaning liquid is preferably 10% by weight or less. This is because the amount of heat generated when the metal nano ink is washed with the washing liquid can be suppressed. The addition amount of hydrogen peroxide in the cleaning liquid is more preferably 5% by weight or less.

  The acid added to the cleaning liquid is not particularly limited. Acids added to the cleaning solution include hydrochloric acid, sulfuric acid, nitric acid, sulfamic acid, phosphoric acid, boric acid, hydrofluoric acid, formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, trimethylacetic acid, capron Acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, glycolic acid, glyoxylic acid, lactic acid, malic acid, tartaric acid Citric acid, benzoic acid, cinnamic acid, toluic acid, naphthoic acid, phthalic acid, trimellitic acid, salicylic acid, gallic acid, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, etidronic acid, etc. Can be used.

  As the acid to be added to the cleaning liquid, it is preferable to use sulfuric acid, hydrochloric acid, nitric acid, formic acid, sulfamic acid, p-toluenesulfonic acid, citric acid, gluconic acid and the like. This is because dissolution of metal nanoparticles is promoted. In particular, it is preferable to use sulfamic acid. This is because the metal nanoparticles can be dissolved without aggregation.

  The amount of acid added to the cleaning liquid is preferably 2% by weight or more. This is because dissolution of metal nanoparticles is promoted. The addition amount of the acid in the cleaning liquid is more preferably 3% by weight or more. On the other hand, the amount of acid added to the cleaning liquid is preferably 30% by weight or less. This is because the amount of heat generated when the metal nano ink is washed with the washing liquid can be suppressed. The addition amount of the acid in the cleaning liquid is more preferably 20% by weight or less.

  Next, the cleaning method according to this embodiment will be described. The cleaning method according to the present embodiment includes a step of cleaning the metal nanoparticles using the above-described cleaning liquid. The object to be cleaned is a flow path of a coating apparatus that applies metal ink. For example, it is possible to employ a technique such as passing the cleaning liquid according to the present embodiment through a nozzle or the like constituting the flow path. According to the cleaning method according to the present embodiment, by using the cleaning liquid described above, the metal nanoparticles can be dissolved, and aggregation, precipitation, and the like until the metal nanoparticles are dissolved are suppressed. A cleaning effect on the metal nano ink can be obtained.

(Example)
Hereinafter, experiments (Sample 1 to Sample 30) were conducted on the solubility of the metal nano ink using the cleaning liquid according to the above embodiment. Specifically, after 1 mL of the metal nano ink was passed through a syringe filter having a filtering diameter of 1 μm, 5 mL of a cleaning liquid was passed through the filter, and it was confirmed whether or not the filter was cleaned.

The composition of the metal nano ink is shown below.
Metal nano ink: Copper nano ink Copper nano particle: Center particle diameter 20nm, 45wt%
Dispersion medium: Diethylene glycol (protic solvent)
Dispersant: PVP-K25, 2.0 wt%

The composition of the cleaning liquid is shown in Table 1. BYK-180 is a trade name “DISPERBYK (registered trademark) -180” manufactured by Big Chemie. BYK-111 is a trade name “DISPERBYK (registered trademark) -111” manufactured by Big Chemie. BYK-2001 is a trade name “DISPERBYK (registered trademark) -2001” manufactured by Big Chemie. BYK-2155 is a trade name “DISPERBYK (registered trademark) -2155” manufactured by Big Chemie. Surfynol 485 is a bilaterally symmetric surfactant having an acetylene group at the center, and is an EO addition product. The surfactant 208G has a double-bonded perfluoroalkenyl structure in the molecule and is a fluorine-based surfactant manufactured by Neos. PEG 600 is a polyethylene glycol having a molecular weight of 600. PVP2500 is a reagent polyvinylpyrrolidone having a weight average molecular weight of about 2500. Prisurf A219B is a polyoxyethylene lauryl ether phosphate ester and is an aqueous dispersant.

(Comparative example)
On the other hand, experiments (Comparative Sample 1 to Comparative Sample 11) were conducted on the solubility of the metal nano-ink using a cleaning liquid that does not satisfy the composition of the cleaning liquid according to the above embodiment. The metal nano ink to be cleaned and the experimental procedure are the same as in the examples. Table 2 shows the composition of the cleaning liquid according to the comparative example.

(analysis)
In Comparative Sample 1 to Comparative Sample 11, good solubility was not obtained. Regarding Comparative Sample 1, it is considered that the weight percentage of water was reduced by 80% by weight or more of the organic solvent, and the dissolution of the metal nanoparticles could not be promoted. Regarding Comparative Sample 2, it is considered that aggregation of metal nanoparticles could not be suppressed because the organic solvent was not added to the cleaning liquid. Regarding Comparative Sample 3, it is considered that the dissolution of the metal nanoparticles could not be promoted because the acid concentration of the cleaning liquid was 1% by weight or less. With respect to Comparative Sample 4, it is considered that the metal nanoparticles could not be sufficiently oxidized because the concentration of hydrogen peroxide in the cleaning liquid was 0.3% by weight or less. Regarding Comparative Samples 5 to 9, it is considered that the metal nanoparticles could not be sufficiently oxidized because hydrogen peroxide was not added as an oxidizing agent. Regarding the comparative sample 10, it is considered that the aggregation and precipitation of metal nanoparticles could not be suppressed because the dispersant was not added to the cleaning liquid. In Comparative Sample 11, since the concentration of the dispersant in the cleaning liquid was 5% by weight or more, it is considered that coagulation was caused due to excessive addition of the polymer compound.

  On the other hand, in samples 1 to 30 of the examples, good solubility in the metal nano ink was obtained by using the cleaning liquid having the composition according to the above embodiment. That is, a good cleaning effect on the metal nano ink was obtained. In sample 3, a particularly good cleaning effect was obtained. This is probably because isopropyl alcohol has a high polarity, promotes dissolution of metal nanoparticles, and has high dispersion stability of metal nanoparticles.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

Claims (9)

An organic solvent, water, an acid, hydrogen peroxide, and a dispersant for dispersing the metal nanoparticles,
The amount of the organic solvent added is less than 80% by weight,
The amount of the dispersant added is less than 5% by weight,
The addition amount of the acid exceeds 1.0% by weight,
A cleaning liquid, wherein the amount of hydrogen peroxide added exceeds 0.3% by weight.   The cleaning liquid according to claim 1, wherein the addition amount of the hydrogen peroxide is 0.5 wt% or more and 10 wt% or less.   The cleaning liquid according to claim 1 or 2, wherein the addition amount of the acid is 2 wt% or more and 30 wt% or less.   The said acid contains any one of a sulfuric acid, hydrochloric acid, nitric acid, formic acid, a sulfamic acid, p-toluenesulfonic acid, a citric acid, and gluconic acid, The Claim 1 characterized by the above-mentioned. Cleaning liquid.   The cleaning liquid according to claim 1, wherein the organic solvent is added in an amount of 5 wt% to 70 wt%.   The organic solvent contains any one of butyl diglycol, isopropyl alcohol, propylene glycol, γ-butyrolactone, N, N-dimethylisobutyramide, acetone, and 1,3-dimethyl-2-imidazolidinone. The cleaning liquid according to any one of claims 1 to 5.   The cleaning liquid according to claim 1, wherein an amount of the dispersant added is 0.01% by weight or more and 3% by weight or less.   The washing | cleaning method characterized by including the process of wash | cleaning a metal nanoparticle using the washing | cleaning liquid as described in any one of Claims 1-7.   The cleaning method according to claim 8, wherein the metal nanoparticles are copper having a nano-order particle diameter.