CN111496266A - Environment-friendly conductive nano copper ink and preparation method thereof - Google Patents

Abstract

The invention discloses a green and environment-friendly conductive nano-copper ink and a preparation method thereof. The preparation method utilizes the cavitation and acoustic flow effects of high-energy ultrasonic waves in a liquid phase to change the chemical reaction mechanism, thereby efficiently obtaining nano-copper particles, Its specific content includes: first, using ascorbic acid as a reducing agent, copper hydroxide as a copper source, and then utilizing the dispersing effect of the product dehydroascorbic acid after the reaction of ascorbic acid, and combining the special effect of ultrasonic waves in the liquid phase, so as to efficiently synthesize the product. The desired copper nanoparticle solution; then, pure copper nanoparticles are obtained by separating from the copper nanoparticle dispersion, and after repeated washing, various organic solvents are added and mixed to obtain nano copper conductive ink. The preparation method has the advantages of unique reaction mechanism, novel preparation method, simple process, low cost, high yield efficiency, environmental friendliness, easy to form large-scale production, etc., and has broad application prospects in the field of printed electronics.

Description

A kind of green and environment-friendly conductive nano-copper ink and preparation method thereof

Technical field:

The invention belongs to the preparation technology of conductive ink, in particular to a green and environment-friendly conductive nano-copper ink and a preparation method thereof, which are widely used in the processing and manufacture of components in printed electronics.

Background technique:

Printed electronics refers to the process of forming conductive lines and patterns on substrates, or forming entire printed circuit boards, using fast, efficient and flexible digital printing technology. Compared with traditional micro-nano processing, the biggest feature of printed electronics is that it does not depend on the conductor or semiconductor properties of the substrate material, and can be deposited on any material in the form of a thin film. In addition, printed electronics also have inherent advantages such as flexibility, large area, low cost, and green environmental protection. Since the 21st century, people have carried out in-depth research on printed electronics, and have discovered its wide application in PCB, OLED, RFID, TFT, photovoltaic devices, sensors, membrane switches and other technical fields. One of the key technologies of printed electronics is the preparation of new conductive inks that are environmentally friendly and low-cost.

Conductive ink is mainly composed of conductive fillers and various additives. According to the difference of its conductive medium, it can be divided into inorganic conductive ink and organic conductive ink. Among them, organic conductive inks have not yet been put into practical use, because of their poor dispersibility in the preparation process, resulting in poor printability during use, and their electrical conductivity is not as good as inorganic conductive inks; and inorganic conductive inks can be divided into Metal-based conductive ink and carbon-based conductive ink, in which the conductivity of carbon-based conductive ink is slightly lower than that of metal-based conductive ink, and the purification is difficult, which makes its manufacturing cost too high, thus limiting its application in printed electronics; metal-based conductive ink The inks mainly include conductive inks composed of nano-gold, silver, copper and other precious metal nanoparticles. Considering the cost and conductivity, copper-based conductive inks are relatively cost-effective, with low cost but almost the same conductivity as silver.

For example, patent CN201010221315.0 discloses a preparation method of nano-copper conductive ink. The preparation method is: dissolving copper salt and protective agent in a solvent, heating up and stirring, adding a small amount of alkaline solution to adjust the pH to 7-10, dripping The reducing agent is continuously stirred and reacted for 30 to 60 minutes, and then cooled to room temperature to obtain a nano-copper dispersion; the nano-copper dispersion is centrifuged, washed, and vacuum-dried at room temperature to obtain nano-copper particles; the nano-copper particles are dispersed in organic The nano-copper conductive ink is obtained by ultrasonic treatment in a solvent; the patent CN201410778114.9 discloses a conductive nano-copper ink and a preparation method thereof. The preparation method includes: using freshly prepared copper hydroxide and mixing it with a protective agent in a first solvent react, and then add L-ascorbic acid to obtain a copper nanoparticle dispersion; separate copper nanoparticles from the copper nanoparticle dispersion, and add a second solvent after washing to obtain a nano-conductive copper ink.

In addition, as CN201910191510.4 discloses a preparation method and application of nano-copper inkjet printing ink, the preparation steps are: preparing polyvinylpyrrolidone precursor solution, by replacing polyvinylpyrrolidone with different average molecular weights to obtain different particle sizes copper nanoparticles, and prepare copper source precursor solution and reducing agent precursor solution, add copper source precursor solution and reducing agent precursor solution to polyvinylpyrrolidone precursor solution dropwise, and stir the oil bath; the obtained product is centrifugally washed and vacuumized Drying to obtain copper nanoparticles; mixing the obtained copper nanoparticles with different particle sizes, then dissolving in a mixed solution of deionized water, ethylene glycol and glycerol, and ultrasonically dispersing to obtain the nano-copper inkjet printing ink. CN200810201967.0 discloses a low reducing agent of sodium hypophosphite, copper sulfate as a precursor, and LD and polyvinylpyrrolidone (PVP) are added as surfactants and dispersants. The liquid-phase reduction method is used to prepare nano-copper conductive ink with stable performance at a temperature of 120-160 °C; the impurity ions in the black water are removed by electrodialysis, and then the content of nano-copper particles in the ink is reduced by distillation under reduced pressure. ~30% (weight percent); the particle size of the nano-copper particles is 20-50nm, and the distribution is uniform.

At present, there are various preparation methods for copper nanoparticles, but there is no report on the preparation of copper nanoparticles by using efficient ultrasonic sonochemical effect. The copper nanoparticles prepared by the method of the present invention have the advantages of simple process, low cost and green Environmental protection, high yield, good oxidation resistance, excellent dispersibility, and easy to form large-scale production.

Invention content:

The purpose of the present invention is to provide a green and environment-friendly conductive nano-copper ink and an efficient preparation method thereof. The advantage of this method is that the cavitation and acoustic flow effects formed by high-power ultrasonic waves in the liquid phase are proposed for the first time. This sonochemical effect changes the basic chemical reduction process. In the high-energy sonochemical process, the free radicals or high-energy species generated by acoustic cavitation diffuse into the liquid phase, triggering a series of chemical reactions to form nanoparticles. In addition, the product of the reducing agent in the method has excellent dispersing effect, so the prepared copper nanoparticles have good dispersibility, simple process, low cost and no pollution to the environment, and can be easily formed into large-scale production. Inks are stable, low cost and suitable for a wide range of printed electronics needs.

Specifically, the technical scheme adopted in the present invention is as follows:

First of all, the present invention provides a preparation method of copper nanoparticles for green and environment-friendly conductive ink, the preparation method includes:

Add copper source into solvent A at 0.2-2mol/L, stir evenly and heat to 50-90℃ to obtain solution a; add reducing agent into solvent A at 2-10mol/L, then add a certain amount of dispersant, After stirring evenly, solution b is obtained; put solution b in a customized ultrasonic device at 50-90 ° C, and quickly dissolve solution b according to the preset ultrasonic parameters; after solution b is mixed evenly, pour solution a quickly In solution b, sonicated for 0.1-1 h, cooled to room temperature, and centrifuged repeatedly to obtain precipitated copper nanoparticles.

The method utilizes the unique chemical reaction characteristics of copper hydroxide and ascorbic acid, and relies on the adsorption of dehydroascorbic acid molecules generated by the reaction on the surface of nanoparticles, thereby preventing the nucleation and growth process of atoms, thereby achieving uniform dispersion and particle size. Unified copper nanoparticles. Secondly, the by-product produced by the reaction is water, and the reaction process is mild and pollution-free, which provides the necessary conditions for the reaction to realize large-scale production with more safety, reliability and environmental protection, which is completely different from the above two patents; The invention introduces ultrasonic waves to accelerate the reaction, thereby achieving better reaction effect and dispersion, which determines the adaptability and printability of copper-based conductive ink in the process of printing electronics.

The copper source is preferably at least one of copper nitrate, copper sulfate, copper hydroxide or copper chloride.

The solvent A is preferably one or at least two mixtures of diethylene glycol, diethylene glycol, ethanol, ethylene glycol and glycerol.

The reducing agent is preferably one or at least two mixtures of sodium hypophosphite, ascorbic acid, hydrazine hydrate, potassium borohydride and methylamine.

The dispersing agent is preferably one or at least two mixtures of polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), polyacrylamide, and Span.

The ultrasonic parameters are preferably: ultrasonic power is 1000-3000W, ultrasonic frequency is 20-200kHz, and ultrasonic intermittent pulse ratio is 1:1-10:1.

Preferably, the temperature of the solution a and the solution b are the same.

Preferably, the centrifugation conditions are centrifugation and washing at 5000-8000 r/min.

Preferably, the centrifugal washing times are 4 times.

The advantages of the materials selected in the process of preparing copper nanoparticles by this method are that no pollutants or complex by-products are generated in the chemical synthesis process, and the reagents have the characteristics of green environmental protection and non-toxicity; in addition, the ultrasonic parameters selected by this method are different from The reagent ratios are optimized through a large number of experimental explorations, and have the advantages of high repeatability, good process stability, and suitability for large-scale production.

Secondly, on the basis of the aforementioned method, the present invention provides a method for preparing a green and environment-friendly conductive nano-copper ink, characterized in that: the preparation method comprises: copper nanoparticles prepared by the preparation method, a third solvent, The binder and foaming agent are mixed according to a certain mass ratio, and then put into a special paste mixer for mixing, and finally the required nano-copper conductive ink is obtained.

Specifically, after mixing the prepared copper nanoparticles, the third solvent B, the binder C, and the foaming agent D according to a certain mass ratio, they are then put into a special paste mixer for mixing, and finally the desired nanoparticle is obtained. Copper conductive ink.

The third solvent B is preferably one or at least two mixtures of ethylene glycol, glycerol, deionized water and ethanol.

The binder C is preferably one or at least two mixtures of ethyl cellulose, polyethylene, alcohol polyurethane, glycerol, terpineol, and polyacrylate.

Described foaming agent D is preferably one or at least two mixtures of azodicarbonamide, ethylene glycol, N-nitroso compound, nitrosamine

Preferably, the mass ratio of the nanoparticles to the solvent is 2:1-6:1.

Preferably, the mass ratio of the nanoparticles to the binder is 20:1-30:1.

Preferably, the mass ratio of the nanoparticles to the foaming agent is 15:1-30:1

Preferably, the rotating speed of the paste mixer is 500-1500r/min.

Preferably, the mixing times are 3-6 times.

Preferably, the solid content of copper nanoparticles in the ink is 50%-90%.

The selection of additive reagents, proportions and preparation parameters for the preparation of copper nano-conductive ink by this method is based on the particularity of the preparation principle of the copper nano-particles. Anti-oxidation, low temperature sintering, improvement of electrical and thermal conductivity.

Further, the present invention provides a green and environment-friendly conductive nano-copper ink, which is prepared by the preparation method.

The solid content of copper nanoparticles in the conductive nano-copper ink is 50%-90%.

The present invention provides a copper nanoparticle conductive ink prepared by the aforementioned method, wherein the particle size of the nanoparticle is about 150 nm, and its dispersibility is excellent. Compared with the technology disclosed at present, the advantages of the present invention are:

(1) The present invention utilizes the unique chemical reaction characteristics of copper hydroxide and ascorbic acid, and the dehydroascorbic acid molecules generated by the reaction are adsorbed on the surface of the nanoparticles, thereby preventing the nucleation and growth process of atoms, thereby realizing uniform Dispersed, uniform size copper nanoparticles. The by-product produced by the reaction is water, and the reaction process is mild and pollution-free, which provides the necessary conditions for the reaction to realize large-scale production with more safety, reliability and environmental protection.

(2) The present invention introduces the effect of ultrasonic waves, and uses the special effect of high-energy ultrasonic waves in the liquid phase to accelerate the reaction, thereby achieving better reaction effect and dispersibility, which determines the copper-based conductive ink in the process of printing electronics. adaptability and printability in .

(3) The copper nanoparticles prepared by the invention have an average particle size of about 150 nm, have excellent dispersibility, and have uniform morphology and particle size distribution. filler.

(4) The present invention does not need protective gas, has low cost, simple process, green environmental protection, ultra-high efficiency, extremely high yield, and is suitable for mass production. In addition, the conductive ink prepared by the invention has good oxidation resistance and electrical conductivity, and has wide application prospects in the field of printed electronics.

Description of drawings:

Fig. 1 is the principle schematic diagram of ultrasonic sonochemical reaction in the process of embodiment 1 of the present invention;

Fig. 2 is the XRD pattern of the nano-copper particle obtained in Example 1 of the present invention;

Figures 3a-3b are SEM images and particle size distribution histograms of the nano-copper particles obtained in Example 1 of the present invention;

Figures 4a-4c are respectively the UV and SEM morphologies during the synthesis of nano-copper particles under different ultrasonic parameters obtained in Examples 1-3 of the present invention;

Fig. 5 is the physical map of the printed electronic circuit obtained in Example 1 of the present invention;

FIG. 6 is a comparison chart of the resistivity of printed electronic pattern circuits in Examples 1-3 of the present invention.

Detailed ways:

The present invention is described in further detail below in conjunction with the accompanying drawings and specific embodiments, but the present invention is not limited thereto:

Example 1

(1) take by weighing 3g copper hydroxide and join in 150ml ethanol solvent and mix well, after continuous stirring, be heated to 50 ℃, obtain solution a after dissolving completely; Take by weighing 15g ascorbic acid as reducing agent, take by weighing 2g polyvinylpyrrolidone ( K-20) as a protective agent, mix the two evenly, add them in 150 ml of ethanol to dissolve, continue to stir and heat to 50°C, and obtain solution b after complete dissolution.

(2) Put solution b in a pulsed ultrasonic device that acts straight down. The preset ultrasonic parameters are: power 1000W, frequency 20KHz, pulse ratio 3:1, after heating to 50°C, pour solution a quickly The solution b was reacted for 10 min, and after the solution changed from light blue to dark red, a copper nanoparticle solution was obtained.

(3) Cooling the copper nanoparticle solution obtained in step (2) to room temperature, and centrifugally washing the solution with 4000 r/min deionized water for 4 times to obtain pure copper nanoparticles.

(4) Mix the freshly prepared copper nanoparticles, ethylene glycol, glycerol, terpineol, ethyl cellulose, etc. in a mass ratio of 7:1:1:0.5:0.5, and then place the rotating speed at 700r /min mixed 5 times in a special paste mixing machine, and finally obtained the copper nanoparticle conductive ink.

Wherein, Figure 1 is a schematic diagram of the principle of ultrasonic sonochemical reaction in the process of Example 1 of the present invention; Figure 2 is the XRD pattern of the nano-copper particles obtained in Example 1 of the present invention; Figures 3a-3b obtained in Example 1 of the present invention SEM image and particle size distribution histogram of nano-copper particles; FIG. 5 is a physical image of the printed electronic circuit obtained in Example 1 of the present invention.

Example 2

(1) take by weighing 5g copper acetate and join in 100ml ethanol solvent and mix well, heat to 100 ℃ after continuous stirring, obtain solution a after being completely dissolved; take by weighing 10g sodium borohydride as reducing agent, take by weighing 2g polyvinylpyrrolidone again (K-20) as a protective agent, mix the two evenly, add them in 100ml of ethanol to dissolve, continue to stir and heat to 100°C, and obtain solution b after complete dissolution.

(2) Put the solution b in a pulsed ultrasonic device with a direct downward action, the preset ultrasonic parameters: power 1200W, frequency 35KHz, pulse ratio 4:1, after heating to 100 ℃, pour solution a quickly The solution b was reacted for 10 min, and after the solution changed from light blue to dark red, a copper nanoparticle solution was obtained.

(3) Cooling the copper nanoparticle solution obtained in step (2) to room temperature, and centrifugally washing the solution with 4000 r/min deionized water for 4 times to obtain pure copper nanoparticles.

(4) Mix the freshly prepared copper nanoparticles, ethylene glycol, glycerol, terpineol, ethyl cellulose, etc. in a mass ratio of 7:1:1:0.5:0.5, and then place the rotating speed at 700r /min mixed 5 times in a special paste mixing machine, and finally obtained the copper nanoparticle conductive ink.

Example 3

(1) take by weighing 10g copper sulfate and join in 100ml ethanol solvent and mix well, heat to 80 ℃ after continuous stirring, obtain solution a after dissolving completely; Take 20g ascorbic acid as reducing agent, take by weighing 5g polyvinylpyrrolidone (K -30) As a protective agent, mix the two evenly and add them into 100 ml of ethanol to dissolve, continue stirring and then heat to 80°C, and obtain solution b after complete dissolution.

(2) Put the solution b in a pulsed ultrasonic device with a direct downward action, the preset ultrasonic parameters: power 1500W, frequency 40KHz, pulse ratio 5:1, after heating to 80 ℃, pour solution a quickly The solution b was reacted for 10 min, and after the solution changed from light blue to dark red, a copper nanoparticle solution was obtained.

(3) Cooling the copper nanoparticle solution obtained in step (2) to room temperature, and centrifugally washing the solution with 4000 r/min deionized water for 4 times to obtain pure copper nanoparticles.

(4) Mix the freshly prepared copper nanoparticles, ethylene glycol, glycerol, terpineol, ethyl cellulose, etc. in a mass ratio of 7:1:1:0.5:0.5, and then place the rotating speed at 700r /min mixed 5 times in a special paste mixing machine, and finally obtained the copper nanoparticle conductive ink.

4a-4c are respectively the UV and SEM morphologies during the synthesis of nano-copper particles under different ultrasonic parameters obtained in Example 1-3 of the present invention; Resistivity comparison chart.

Example 4

(1) Weigh 2g of graphite powder and add it to 35ml of sulfuric acid solution with a mass fraction of 98%, stir evenly for 2h to obtain solution a; then weigh 6g of KMnO powder and slowly add it to solution a, continue stirring and heat to ₄₀ °C The reaction was carried out for 30 min, and then 90 ml of water was added to dilute the resulting solution with vigorous stirring to obtain a dark brown suspension c.

(2) 150 ml of distilled water and 30% H ₂ O ₂ solution (10 ml) were added to the suspension c to terminate the reaction. After continuous stirring for 2 hours, centrifugation was repeated with 5% aqueous HCl to remove residual metal ions. Then, the centrifugation process was repeated with distilled water until the pH of the solution became neutral.

(3) 0.2 g of the synthesized graphite oxide was redispersed in 200 ml of distilled water, and sonicated for 30 min to exfoliate the graphite oxide into a single layer of graphene oxide (GO), which was further used in the synthesis of graphene.

(4) NaOH solution was added dropwise to graphene oxide solution (0.2g/200mL) to adjust pH to 10, then 2mL of hydrazine was added, and the whole reaction was irradiated by ultrasonic for 2h. A graphene nanosheet solution is obtained.

(5) Thoroughly wash the obtained graphene nanosheets with distilled water, and centrifuge at 12,000 rpm for 10 minutes to remove residues. This process was repeated several times until the synthesized product was free of trace impurities, resulting in pure graphene nanosheets.

Example 5

(1) Dissolve 0.01mol% ferrocene and add it to 50ml of p-xylene solution with a mass fraction of 99%, stir evenly to obtain solution a; then weigh 2g of silicon powder (2-5mm in diameter) and slowly add it to the solution In a, the reaction was continued for 30 min after stirring evenly.

(2) Deeply penetrate the ultrasonic horn with a diameter of 6mm into the solution a, under normal temperature and pressure, through the preset parameters of ultrasonic power of 200W and amplitude of 65%, continue to output high-energy ultrasonic waves to the solution for 20min, and wait for the reaction Upon completion, the solution turned grey and a black precipitate developed.

(3) The obtained precipitate was thoroughly washed with distilled water, and centrifuged at 12,000 rpm for 10 minutes to remove residues. This process is repeated several times until there are no trace impurities in the synthesized product, thereby obtaining pure carbon nanotubes.

The above-mentioned embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations, The simplification should be equivalent replacement manners, which are all included in the protection scope of the present invention.

Claims (10)

1. a preparation method for the copper nanoparticles of green and environment-friendly conductive ink, is characterized in that: described preparation method comprises: adding copper source in solvent A by 0.2-2mol/L, after stirring, be heated to 50-50- 90 °C to obtain solution a; add the reducing agent to solvent A at 2-10 mol/L, then add a certain amount of dispersant, stir evenly to obtain solution b; place solution b in an ultrasonic device at 50-90 °C, Ultrasound is applied to dissolve solution b rapidly; after solution b is mixed uniformly, solution a is quickly poured into solution b, and the ultrasonic wave is continued for 0.1-1 h, then cooled to room temperature, and the precipitated copper nanoparticles are obtained after repeated centrifugation for many times. 2. preparation method according to claim 1 is characterized in that: described copper source is selected from at least one in copper nitrate, copper sulfate, copper hydroxide or copper chloride; Solvent A is selected from - diethyl acetal One or at least two mixtures of glycol, diethylene glycol, ethanol, ethylene glycol and glycerol; the reducing agent is selected from sodium hypophosphite, ascorbic acid, hydrazine hydrate, potassium borohydride, methylamine or a mixture of at least two. 3. preparation method according to claim 1, is characterized in that: described ultrasonic parameter is set as: ultrasonic power is 1000-3000W, ultrasonic frequency is 20-200kHz, ultrasonic intermittent pulse ratio is 1:1-10:1 . 4 . The preparation method according to claim 1 , wherein the temperature of the solution a and the solution b are the same; and the centrifugal condition is 5000-8000 r/min. 5 . 5. A method for preparing a green and environment-friendly conductive nano-copper ink, characterized in that: the preparation method comprises: the copper nanoparticles prepared by the preparation method according to any one of claims 1-3, a third solvent, a viscosity After mixing the binding agent and the foaming agent according to a certain mass ratio, they are put into a special paste mixing machine for mixing, and finally the required nano-copper conductive ink is obtained. 6. preparation method according to claim 5 is characterized in that the selection of the third solvent is: the third solvent is selected from one or at least two mixtures of deionized water, ethanol, ethylene glycol, glycerol; The binding agent is selected from one or at least two mixtures of glycerol, terpineol, ethyl cellulose, polyethylene, alcohol polyurethane and polyacrylate; the foaming agent is selected from N-nitroso compounds, azobis One or at least two mixtures of formamide, ethylene glycol, nitrosamine. 7. The preparation method according to claim 5, wherein the solid content of copper nanoparticles in the ink is 50%-90%. 8. The preparation method according to claim 5 or 6, wherein the mass ratio of the copper nanoparticles to the third solvent is 2:1-6:1; the mass ratio of the nanoparticles to the binder is 20:1-30:1; the mass ratio of the nanoparticles to the foaming agent is 15:1-30:1. 9 . A green and environment-friendly conductive nano-copper ink, characterized in that, the ink is prepared by the preparation method according to any one of claims 1-8. 10 . The environmentally friendly conductive nano-copper ink according to claim 9 , wherein the solid content of copper nanoparticles in the ink is 50%-90%. 11 .

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